1,178 results on '"C. Slater"'
Search Results
2. Author Correction: The adipokine leptin modulates adventitial pericyte functions by autocrine and paracrine signalling
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Federica Riu, Sadie C. Slater, Eva Jover Garcia, Iker Rodriguez-Arabaolaza, Valeria Alvino, Elisa Avolio, Giuseppe Mangialardi, Andrea Cordaro, Simon Satchell, Carlo Zebele, Andrea Caporali, Gianni Angelini, and Paolo Madeddu
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Medicine ,Science - Published
- 2024
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3. Malaria in pregnancy (MiP) studies assessing the clinical performance of highly sensitive rapid diagnostic tests (HS-RDT) for Plasmodium falciparum detection
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Xavier C. Ding, Sandra Incardona, Elisa Serra-Casas, Sarah C. Charnaud, Hannah C. Slater, Gonzalo J. Domingo, Emily R. Adams, Feiko O. ter Kuile, Aaron M. Samuels, Simon Kariuki, and Sabine Dittrich
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Malaria ,Pregnancy ,Rapid diagnostic test ,RDT ,Highly sensitive rapid diagnostic test ,HS-RDT ,Arctic medicine. Tropical medicine ,RC955-962 ,Infectious and parasitic diseases ,RC109-216 - Abstract
Abstract Background Rapid diagnostic tests (RDTs) are effective tools to diagnose and inform the treatment of malaria in adults and children. The recent development of a highly sensitive rapid diagnostic test (HS-RDT) for Plasmodium falciparum has prompted questions over whether it could improve the diagnosis of malaria in pregnancy and pregnancy outcomes in malaria endemic areas. Methods This landscape review collates studies addressing the clinical performance of the HS-RDT. Thirteen studies were identified comparing the HS-RDT and conventional RDT (co-RDT) to molecular methods to detect malaria in pregnancy. Using data from five completed studies, the association of epidemiological and pregnancy-related factors on the sensitivity of HS-RDT, and comparisons with co-RDT were investigated. The studies were conducted in 4 countries over a range of transmission intensities in largely asymptomatic women. Results Sensitivity of both RDTs varied widely (HS-RDT range 19.6 to 85.7%, co-RDT range 22.8 to 82.8% compared to molecular testing) yet HS-RDT detected individuals with similar parasite densities across all the studies including different geographies and transmission areas [geometric mean parasitaemia around 100 parasites per µL (p/µL)]. HS-RDTs were capable of detecting low-density parasitaemias and in one study detected around 30% of infections with parasite densities of 0–2 p/µL compared to the co-RDT in the same study which detected around 15%. Conclusion The HS-RDT has a slightly higher analytical sensitivity to detect malaria infections in pregnancy than co-RDT but this mostly translates to only fractional and not statistically significant improvement in clinical performance by gravidity, trimester, geography or transmission intensity. The analysis presented here highlights the need for larger and more studies to evaluate incremental improvements in RDTs. The HS-RDT could be used in any situation where co-RDT are currently used for P. falciparum diagnosis, if storage conditions can be adhered to.
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- 2023
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4. Performance and utility of more highly sensitive malaria rapid diagnostic tests
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Hannah C. Slater, Xavier C. Ding, Sophia Knudson, Daniel J. Bridges, Hawela Moonga, Neil J. Saad, Martin De Smet, Adam Bennett, Sabine Dittrich, Laurence Slutsker, and Gonzalo J. Domingo
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HS-RDT ,Rapid diagnostic test ,Malaria diagnosis ,Cross-sectional surveys ,Infectious and parasitic diseases ,RC109-216 - Abstract
Abstract Background A new more highly sensitive rapid diagnostic test (HS-RDT) for Plasmodium falciparum malaria (Alere™/Abbott Malaria Ag P.f RDT [05FK140], now called NxTek™ Eliminate Malaria Ag Pf) was launched in 2017. The test has already been used in many research studies in a wide range of geographies and use cases. Methods In this study, we collate all published and available unpublished studies that use the HS-RDT and assess its performance in (i) prevalence surveys, (ii) clinical diagnosis, (iii) screening pregnant women, and (iv) active case detection. Two individual-level data sets from asymptomatic populations are used to fit logistic regression models to estimate the probability of HS-RDT positivity based on histidine-rich protein 2 (HRP2) concentration and parasite density. The performance of the HS-RDT in prevalence surveys is estimated by calculating the sensitivity and positive proportion in comparison to polymerase chain reaction (PCR) and conventional malaria RDTs. Results We find that across 18 studies, in prevalence surveys, the mean sensitivity of the HS-RDT is estimated to be 56.1% (95% confidence interval [CI] 46.9–65.4%) compared to 44.3% (95% CI 32.6–56.0%) for a conventional RDT (co-RDT) when using nucleic acid amplification techniques as the reference standard. In studies where prevalence was estimated using both the HS-RDT and a co-RDT, we found that prevalence was on average 46% higher using a HS-RDT compared to a co-RDT. For use in clinical diagnosis and screening pregnant women, the HS-RDT was not significantly more sensitive than a co-RDT. Conclusions Overall, the evidence presented here suggests that the HS-RDT is more sensitive in asymptomatic populations and could provide a marginal improvement in clinical diagnosis and screening pregnant women. Although the HS-RDT has limited temperature stability and shelf-life claims compared to co-RDTs, there is no evidence to suggest, given this test has the same cost as current RDTs, it would have any negative impacts in terms of malaria misdiagnosis if it were widely used in all four population groups explored here.
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- 2022
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5. Repeat Ivermectin Mass Drug Administrations for Malaria Control II: Protocol for a Double-blind, Cluster-Randomized, Placebo-Controlled Trial for the Integrated Control of Malaria
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Brian D Foy, Anthony Some, Tereza Magalhaes, Lyndsey Gray, Sangeeta Rao, Emmanuel Sougue, Conner L Jackson, John Kittelson, Hannah C Slater, Teun Bousema, Ollo Da, A Gafar V Coulidiaty, McKenzie Colt, Martina Wade, Kacey Richards, A Fabrice Some, Roch K Dabire, and Sunil Parikh
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Medicine ,Computer applications to medicine. Medical informatics ,R858-859.7 - Abstract
BackgroundThe gains made against malaria have stagnated since 2015, threatened further by increasing resistance to insecticides and antimalarials. Improvement in malaria control necessitates a multipronged strategy, which includes the development of novel tools. One such tool is mass drug administration (MDA) with endectocides, primarily ivermectin, which has shown promise in reducing malaria transmission through lethal and sublethal impacts on the mosquito vector. ObjectiveThe primary objective of the study is to assess the impact of repeated ivermectin MDA on malaria incidence in children aged ≤10 years. MethodsRepeat Ivermectin MDA for Malaria Control II is a double-blind, placebo-controlled, cluster-randomized, and parallel-group trial conducted in a setting with intense seasonal malaria transmission in Southwest Burkina Faso. The study included 14 discrete villages: 7 (50%) randomized to receive standard measures (seasonal malaria chemoprevention [SMC] and bed net use for children aged 3 to 59 months) and placebo, and 7 (50%) randomized to receive standard measures and monthly ivermectin MDA at 300 μg/kg for 3 consecutive days, provided under supervision to all eligible village inhabitants, over 2 successive rainy seasons. Nonpregnant individuals >90 cm in height were eligible for ivermectin MDA, and cotreatment with ivermectin and SMC was not permitted. The primary outcome is malaria incidence in children aged ≤10 years, as assessed by active case surveillance. The secondary safety outcome of repeated ivermectin MDA was assessed through active and passive adverse event monitoring. ResultsThe trial intervention was conducted from July to November in 2019 and 2020, with additional sampling of humans and mosquitoes occurring through February 2022 to assess postintervention changes in transmission patterns. Additional human and entomological assessments were performed over the 2 years in a subset of households from 6 cross-sectional villages. A subset of individuals underwent additional sampling in 2020 to characterize ivermectin pharmacokinetics and pharmacodynamics. Analysis and unblinding will commence once the database has been completed, cleaned, and locked. ConclusionsOur trial represents the first study to directly assess the impact of a novel approach for malaria control, ivermectin MDA as a mosquitocidal agent, layered into existing standard-of-care interventions. The study was designed to leverage the current SMC deployment infrastructure and will provide evidence regarding the additional benefit of ivermectin MDA in reducing malaria incidence in children. Trial RegistrationsClinicalTrials.gov NCT03967054; https://clinicaltrials.gov/ct2/show/NCT03967054 and Pan African Clinical Trials Registry PACT201907479787308; https://pactr.samrc.ac.za/TrialDisplay.aspx?TrialID=8219 International Registered Report Identifier (IRRID)DERR1-10.2196/41197
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- 2023
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6. Ultra-sensitive RDT performance and antigen dynamics in a high-transmission Plasmodium falciparum setting in Mali
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Emily N. Reichert, Jen C. C. Hume, Issaka Sagara, Sara A. Healy, Mahamadoun H. Assadou, Merepen A. Guindo, Rebecca Barney, Andy Rashid, Ihn Kyung Yang, Allison Golden, Gonzalo J. Domingo, Patrick E. Duffy, and Hannah C. Slater
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Malaria ,Ultra-sensitive RDT ,Antigenemia ,HRP2 ,pLDH ,Arctic medicine. Tropical medicine ,RC955-962 ,Infectious and parasitic diseases ,RC109-216 - Abstract
Abstract Background The recent expansion of tools designed to accurately quantify malaria parasite-produced antigens has enabled us to evaluate the performance of rapid diagnostic tests (RDTs) as a function of the antigens they detect—typically histidine rich protein 2 (HRP2) or lactate dehydrogenase (LDH). Methods For this analysis, whole blood specimens from a longitudinal study in Bancoumana, Mali were used to evaluate the performance of the ultra-sensitive HRP2-based Alere™ Malaria Ag P.f RDT (uRDT). The samples were collected as part of a transmission-blocking vaccine trial in a high transmission region for Plasmodium falciparum malaria. Furthermore, antigen dynamics after successful anti-malarial drug treatment were evaluated in these samples using the Q-Plex Human Malaria Array (4-Plex) to quantify antigen concentrations. Results The uRDT had a 50% probability of a positive result at 207 pg/mL HRP2 [95% credible interval (CrI) 160–268]. Individuals with symptomatic infection remained positive by uRDT for a median of 33 days [95% confidence interval (CI) 28–47] post anti-malarial drug treatment. Biphasic exponential decay models accurately captured the population level post-treatment dynamics of both HRP2 and Plasmodium LDH (pLDH), with the latter decaying more rapidly. Motivated by these differences in rates of decay, a novel algorithm that used HRP2:pLDH ratios to predict if an individual had active versus recently cleared P. falciparum infection was developed. The algorithm had 77.5% accuracy in correctly classifying antigen-positive individuals as those with and without active infection. Conclusions These results characterize the performance of the ultra-sensitive RDT and demonstrate the potential for emerging antigen-quantifying technologies in the field of malaria diagnostics to be helpful tools in distinguishing between active versus recently cleared malaria infections.
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- 2020
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7. The temporal dynamics and infectiousness of subpatent Plasmodium falciparum infections in relation to parasite density
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Hannah C. Slater, Amanda Ross, Ingrid Felger, Natalie E. Hofmann, Leanne Robinson, Jackie Cook, Bronner P. Gonçalves, Anders Björkman, Andre Lin Ouedraogo, Ulrika Morris, Mwinyi Msellem, Cristian Koepfli, Ivo Mueller, Fitsum Tadesse, Endalamaw Gadisa, Smita Das, Gonzalo Domingo, Melissa Kapulu, Janet Midega, Seth Owusu-Agyei, Cécile Nabet, Renaud Piarroux, Ogobara Doumbo, Safiatou Niare Doumbo, Kwadwo Koram, Naomi Lucchi, Venkatachalam Udhayakumar, Jacklin Mosha, Alfred Tiono, Daniel Chandramohan, Roly Gosling, Felista Mwingira, Robert Sauerwein, Richard Paul, Eleanor M Riley, Nicholas J White, Francois Nosten, Mallika Imwong, Teun Bousema, Chris Drakeley, and Lucy C Okell
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Science - Abstract
The role of subpatent infections for malaria transmission and elimination is unclear. Here, Slater et al. analyse several malaria datasets to quantify the density, detectability, course of infection and infectiousness of subpatent infections.
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- 2019
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8. Gender Discrimination and Reporting Experiences among Academic Pediatric Faculty: A Qualitative, Single-institution Study
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Abby R. Rosenberg, Krysta S. Barton, Miranda C. Bradford, Shaquita Bell, Linda Quan, Anita Thomas, Leslie Walker-Harding, and Anne C. Slater
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Pediatrics, Perinatology and Child Health - Abstract
Gender-harassment is well-described in academic medicine, including pediatrics. We explored academic pediatricians' qualitative descriptions of: 1) workplace gender-harassment; 2) its professional and emotional tolls; 3) barriers to and outcomes of reporting gender-harassment; and 4) tools to intervene.We conducted a cross-sectional, anonymous, survey-based study within a single, large pediatrics department. Surveys included demographic items, validated measures to assess prevalence of gender-harassment, and optional, free-text boxes to elaborate. Here, we present the directed content analyses of free-text responses. Two trained qualitative researchers coded participant comments to identify types of gender-harassment, its impact, and participants' experiences reporting it. Final agreement between coders was outstanding (Kappa0.9). A secondary, inductive analysis illustrated the emotional burdens of and opportunities to interrupt gender-harassment.Of 524 total faculty, 290 (55%) completed the survey and 144 (27% of total, 50% of survey-respondents) provided text-responses. This sub-cohort was predominantly white women5 years on-faculty. Compared to the full cohort, sub-cohort participants had more commonly witnessed/experienced workplace-harassment; 92% of sub-cohort women and 52% of men endorsed fear of reporting it. Respondents described harassment by institutional staff (24% of respondents), patients/families (35%), colleagues (50%), supervisors/leadership (50%), and the system (63%). Women used stronger emotional descriptors than men (ie, "humiliated" vs "uncomfortable"). Only 19% of women (and no men) had reported witnessed/experienced harassment; 24% of those described a negative consequence and 95% noted that no changes were made thereafter.This single-center study suggests gender-harassment in academic pediatrics is common. Faculty feel fear and futility reporting it.
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- 2023
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9. Quantifying Plasmodium falciparum infections clustering within households to inform household-based intervention strategies for malaria control programs: An observational study and meta-analysis from 41 malaria-endemic countries.
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Gillian Stresman, Charlie Whittaker, Hannah C Slater, Teun Bousema, and Jackie Cook
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Medicine - Abstract
BackgroundReactive malaria strategies are predicated on the assumption that individuals infected with malaria are clustered within households or neighbourhoods. Despite the widespread programmatic implementation of reactive strategies, little empirical evidence exists as to whether such strategies are appropriate and, if so, how they should be most effectively implemented.Methods and findingsWe collated 2 different datasets to assess clustering of malaria infections within households: (i) demographic health survey (DHS) data, integrating household information and patent malaria infection, recent fever, and recent treatment status in children; and (ii) data from cross-sectional and reactive detection studies containing information on the household and malaria infection status (patent and subpatent) of all-aged individuals. Both datasets were used to assess the odds of infections clustering within index households, where index households were defined based on whether they contained infections detectable through one of 3 programmatic strategies: (a) Reactive Case Detection (RACD) classifed by confirmed clinical cases, (b) Mass Screen and Treat (MSAT) classifed by febrile, symptomatic infections, and (c) Mass Test and Treat (MTAT) classifed by infections detectable using routine diagnostics. Data included 59,050 infections in 208,140 children under 7 years old (median age = 2 years, minimum = 2, maximum = 7) by microscopy/rapid diagnostic test (RDT) from 57 DHSs conducted between November 2006 and December 2018 from 23 African countries. Data representing 11,349 infections across all ages (median age = 22 years, minimum = 0.5, maximum = 100) detected by molecular tools in 132,590 individuals in 43 studies published between April 2006 and May 2019 in 20 African, American, Asian, and Middle Eastern countries were obtained from the published literature. Extensive clustering was observed-overall, there was a 20.40 greater (95% credible interval [CrI] 0.35-20.45; P < 0.001) odds of patent infections (according to the DHS data) and 5.13 greater odds (95% CI 3.85-6.84; P < 0.001) of molecularly detected infections (from the published literature) detected within households in which a programmatically detectable infection resides. The strongest degree of clustering identified by polymerase chain reaction (PCR)/ loop mediated isothermal amplification (LAMP) was observed using the MTAT strategy (odds ratio [OR] = 6.79, 95% CI 4.42-10.43) but was not significantly different when compared to MSAT (OR = 5.2, 95% CI 3.22-8.37; P-difference = 0.883) and RACD (OR = 4.08, 95% CI 2.55-6.53; P-difference = 0.29). Across both datasets, clustering became more prominent when transmission was low. However, limitations to our analysis include not accounting for any malaria control interventions in place, malaria seasonality, or the likely heterogeneity of transmission within study sites. Clustering may thus have been underestimated.ConclusionsIn areas where malaria transmission is peri-domestic, there are programmatic options for identifying households where residual infections are likely to be found. Combining these detection strategies with presumptively treating residents of index households over a sustained time period could contribute to malaria elimination efforts.
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- 2020
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10. The adipokine leptin modulates adventitial pericyte functions by autocrine and paracrine signalling
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Federica Riu, Sadie C. Slater, Eva Jover Garcia, Iker Rodriguez-Arabaolaza, Valeria Alvino, Elisa Avolio, Giuseppe Mangialardi, Andrea Cordaro, Simon Satchell, Carlo Zebele, Andrea Caporali, Gianni Angelini, and Paolo Madeddu
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Medicine ,Science - Abstract
Abstract Transplantation of adventitial pericytes (APCs) improves recovery from tissue ischemia in preclinical animal models by still unknown mechanisms. This study investigates the role of the adipokine leptin (LEP) in the regulation of human APC biological functions. Transcriptomic analysis of APCs showed components of the LEP signalling pathway are modulated by hypoxia. Kinetic studies indicate cultured APCs release high amounts of immunoreactive LEP following exposure to hypoxia, continuing upon return to normoxia. Secreted LEP activates an autocrine/paracrine loop through binding to the LEP receptor (LEPR) and induction of STAT3 phosphorylation. Titration studies using recombinant LEP and siRNA knockdown of LEP or LEPR demonstrate the adipokine exerts important regulatory roles in APC growth, survival, migration and promotion of endothelial network formation. Heterogeneity in LEP expression and secretion may influence the reparative proficiency of APC therapy. Accordingly, the levels of LEP secretion predict the microvascular outcome of APCs transplantation in a mouse limb ischemia model. Moreover, we found that the expression of the Lepr gene is upregulated on resident vascular cells from murine ischemic muscles, thus providing a permissive milieu to transplanted LEP-expressing APCs. Results highlight a new mechanism responsible for APC adaptation to hypoxia and instrumental to vascular repair.
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- 2017
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11. A novel model fitted to multiple life stages of malaria for assessing efficacy of transmission-blocking interventions
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Ellie Sherrard-Smith, Thomas S. Churcher, Leanna M. Upton, Katarzyna A. Sala, Sara E. Zakutansky, Hannah C. Slater, Andrew M. Blagborough, and Michael Betancourt
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Atovaquone ,Plasmodium berghei ,Transmission-blocking drugs ,Transmission-blocking vaccines ,Arctic medicine. Tropical medicine ,RC955-962 ,Infectious and parasitic diseases ,RC109-216 - Abstract
Abstract Background Transmission-blocking interventions (TBIs) aim to eliminate malaria by reducing transmission of the parasite between the host and the invertebrate vector. TBIs include transmission-blocking drugs and vaccines that, when given to humans, are taken up by mosquitoes and inhibit parasitic development within the vector. Accurate methodologies are key to assess TBI efficacy to ensure that only the most potent candidates progress to expensive and time-consuming clinical trials. Measuring intervention efficacy can be problematic because there is substantial variation in the number of parasites in both the host and vector populations, which can impact transmission even in laboratory settings. Methods A statistically robust empirical method is introduced for estimating intervention efficacy from standardised population assay experiments. This method will be more reliable than simple summary statistics as it captures changes in parasite density in different life-stages. It also allows efficacy estimates at a finer resolution than previous methods enabling the impact of the intervention over successive generations to be tracked. A major advantage of the new methodology is that it makes no assumptions on the population dynamics of infection. This enables both host-to-vector and vector-to-host transmission to be density-dependent (or other) processes and generates easy-to-understand estimates of intervention efficacy. Results This method increases the precision of intervention efficacy estimates and demonstrates that relying on changes in infection prevalence (the proportion of infected hosts) alone may be insufficient to capture the impact of TBIs, which also suppress parasite density in secondarily infected hosts. Conclusions The method indicates that potentially useful, partially effective TBIs may require multiple infection cycles before substantial reductions in prevalence are observed, despite more rapidly suppressing parasite density. Accurate models to quantify efficacy will have important implications for understanding how TBI candidates might perform in field situations and how they should be evaluated in clinical trials.
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- 2017
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12. False-negative malaria rapid diagnostic test results and their impact on community-based malaria surveys in sub-Saharan Africa
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Jonathan B Parr, Oliver J Watson, Kelsey Marie Sumner, Mark Janko, Peter Winskill, Hannah C Slater, Azra Ghani, and Steven R Meshnick
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Medicine (General) ,R5-920 ,Infectious and parasitic diseases ,RC109-216 - Abstract
Surveillance and diagnosis of Plasmodium falciparum malaria relies predominantly on rapid diagnostic tests (RDT). However, false-negative (FN) RDT results are known to occur for a variety of reasons, including operator error, poor storage conditions, pfhrp2/3 gene deletions, poor performance of specific RDT brands and lots, and low-parasite density infections. We used RDT and microscopy results from 85 000 children enrolled in Demographic Health Surveys and Malaria Indicator Surveys from 2009 to 2015 across 19 countries to explore the distribution of and risk factors for FN-RDTs in sub-Saharan Africa, where malaria’s impact is greatest. We sought to (1) identify spatial and demographic patterns of FN-RDT results, defined as a negative RDT but positive gold standard microscopy test, and (2) estimate the percentage of infections missed within community-based malaria surveys due to FN-RDT results. Across all studies, 19.9% (95% CI 19.0% to 20.9%) of microscopy-positive subjects were negative by RDT. The distribution of FN-RDT results was spatially heterogeneous. The variance in FN-RDT results was best explained by the prevalence of malaria, with an increase in FN-RDT results observed at lower transmission intensities, among younger subjects, and in urban areas. The observed proportion of FN-RDT results was not predicted by differences in RDT brand or lot performance alone. These findings characterise how the probability of detection by RDTs varies in different transmission settings and emphasise the need for careful interpretation of prevalence estimates based on surveys employing RDTs alone. Further studies are needed to characterise the cost-effectiveness of improved malaria diagnostics (eg, PCR or highly sensitive RDTs) in community-based surveys, especially in regions of low transmission intensity or high urbanicity.
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- 2019
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13. Impact of seasonal variations in Plasmodium falciparum malaria transmission on the surveillance of pfhrp2 gene deletions
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Oliver John Watson, Robert Verity, Azra C Ghani, Tini Garske, Jane Cunningham, Antoinette Tshefu, Melchior K Mwandagalirwa, Steven R Meshnick, Jonathan B Parr, and Hannah C Slater
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radid diagnostic tests ,pfhrp2-deletion ,mapping ,mathematical modelling ,Medicine ,Science ,Biology (General) ,QH301-705.5 - Abstract
Ten countries have reported pfhrp2/pfhrp3 gene deletions since the first observation of pfhrp2-deleted parasites in 2012. In a previous study (Watson et al., 2017), we characterised the drivers selecting for pfhrp2/3 deletions and mapped the regions in Africa with the greatest selection pressure. In February 2018, the World Health Organization issued guidance on investigating suspected false-negative rapid diagnostic tests (RDTs) due to pfhrp2/3 deletions. However, no guidance is provided regarding the timing of investigations. Failure to consider seasonal variation could cause premature decisions to switch to alternative RDTs. In response, we have extended our methods and predict that the prevalence of false-negative RDTs due to pfhrp2/3 deletions is highest when sampling from younger individuals during the beginning of the rainy season. We conclude by producing a map of the regions impacted by seasonal fluctuations in pfhrp2/3 deletions and a database identifying optimum sampling intervals to support malaria control programmes.
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- 2019
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14. Author Correction: The temporal dynamics and infectiousness of subpatent Plasmodium falciparum infections in relation to parasite density
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Hannah C. Slater, Amanda Ross, Ingrid Felger, Natalie E. Hofmann, Leanne Robinson, Jackie Cook, Bronner P. Gonçalves, Anders Björkman, Andre Lin Ouedraogo, Ulrika Morris, Mwinyi Msellem, Cristian Koepfli, Ivo Mueller, Fitsum Tadesse, Endalamaw Gadisa, Smita Das, Gonzalo Domingo, Melissa Kapulu, Janet Midega, Seth Owusu-Agyei, Cécile Nabet, Renaud Piarroux, Ogobara Doumbo, Safiatou Niare Doumbo, Kwadwo Koram, Naomi Lucchi, Venkatachalam Udhayakumar, Jacklin Mosha, Alfred Tiono, Daniel Chandramohan, Roly Gosling, Felista Mwingira, Robert Sauerwein, Richard Paul, Eleanor M Riley, Nicholas J White, Francois Nosten, Mallika Imwong, Teun Bousema, Chris Drakeley, and Lucy C Okell
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Science - Abstract
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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- 2019
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15. PImMS: A self-triggered, 25ns resolution monolithic CMOS sensor for Time-of-Flight and Imaging Mass Spectrometry.
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Iain Sedgwick, A. Clark, J. Crooks, R. Turchetta, L. Hill, J. J. John, Andrei Nomerotski, R. Pisarczyk, M. Brouard, Sara H. Gardiner, E. Halford, J. Lee, M. L. Lipciuc, C. Slater, C. Vallance, E. S. Wilman, B. Winter, and W. H. Yuen
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- 2012
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16. Contemporary Series of Robotic-Assisted Distal Ureteral Reconstruction Utilizing Side Docking Position
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Rick C. Slater, Nicholas J. Farber, Julie M. Riley, Yaniv Shilo, and Michael C. Ost
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Video-Assisted Surgery ,Ureter ,Reconstructive Surgical Procedures ,Diseases of the genitourinary system. Urology ,RC870-923 - Abstract
Purpose: The robot-assisted approach to distal ureteral reconstruction is increasingly utilized. Traditionally, the robot is docked between the legs in lithotomy position resulting in limited bladder access for stent placement. We examined the use of side docking of the daVinci robot® to perform distal ureteral reconstruction. Materials and Methods: A retrospective review of distal ureteral reconstruction (ureteral reimplantation and uretero-ureterostomy) executed robotically was performed at a single institution by a single surgeon. The daVinci robotic® Si surgical platform was positioned at the right side of the patient facing towards the head of the patient, i.e. side docking. Results: A total of 14 cases were identified from 2011–2013. Nine patients underwent ureteral reimplantation for ureteral injury, two for vesicoureteral reflux, one for ureteral stricture, and one for megaureter. One patient had an uretero-ureterostomy for a distal stricture. Three patients required a Boari flap due to extensive ureteral injury. Mean operative time was 286 minutes (189–364), mean estimated blood loss was 40cc (10–200), and mean length of stay was 2.3 days (1–4). Follow-up renal ultrasound was available for review in 10/14 patients and revealed no long-term complications in any patient. Mean follow-up was 20.7 months (0.1–59.3). Conclusion: Robot-assisted laparoscopic distal ureteral reconstruction is safe and effective. Side docking of the robot allows ready access to the perineum and acceptable placement of the robot to successfully complete ureteral repair.
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- 2015
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17. The US President's Malaria Initiative, Plasmodium falciparum transmission and mortality: A modelling study.
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Peter Winskill, Hannah C Slater, Jamie T Griffin, Azra C Ghani, and Patrick G T Walker
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Medicine - Abstract
BACKGROUND:Although significant progress has been made in reducing malaria transmission globally in recent years, a large number of people remain at risk and hence the gains made are fragile. Funding lags well behind amounts needed to protect all those at risk and ongoing contributions from major donors, such as the President's Malaria Initiative (PMI), are vital to maintain progress and pursue further reductions in burden. We use a mathematical modelling approach to estimate the impact of PMI investments to date in reducing malaria burden and to explore the potential negative impact on malaria burden should a proposed 44% reduction in PMI funding occur. METHODS AND FINDINGS:We combined an established mathematical model of Plasmodium falciparum transmission dynamics with epidemiological, intervention, and PMI-financing data to estimate the contribution PMI has made to malaria control via funding for long-lasting insecticide treated nets (LLINs), indoor residual spraying (IRS), and artemisinin combination therapies (ACTs). We estimate that PMI has prevented 185 million (95% CrI: 138 million, 230 million) malaria cases and saved 940,049 (95% CrI: 545,228, 1.4 million) lives since 2005. If funding is maintained, PMI-funded interventions are estimated to avert a further 162 million (95% CrI: 116 million, 194 million) cases, saving a further 692,589 (95% CrI: 392,694, 955,653) lives between 2017 and 2020. With an estimate of US$94 (95% CrI: US$51, US$166) per Disability Adjusted Life Year (DALY) averted, PMI-funded interventions are highly cost-effective. We also demonstrate the further impact of this investment by reducing caseloads on health systems. If a 44% reduction in PMI funding were to occur, we predict that this loss of direct aid could result in an additional 67 million (95% CrI: 49 million, 82 million) cases and 290,649 (95% CrI: 167,208, 395,263) deaths between 2017 and 2020. We have not modelled indirect impacts of PMI funding (such as health systems strengthening) in this analysis. CONCLUSIONS:Our model estimates that PMI has played a significant role in reducing malaria cases and deaths since its inception. Reductions in funding to PMI could lead to large increases in the number of malaria cases and deaths, damaging global goals of malaria control and elimination.
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- 2017
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18. Model citizen – Authors' reply
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Oliver J Brady, Hannah C Slater, Peter Pemberton-Ross, Edward Wenger, Richard J Maude, Azra C Ghani, Melissa A Penny, Jaline Gerardin, Lisa J White, Nakul Chitnis, Ricardo Aguas, Simon I Hay, David L Smith, Erin M Stuckey, Emelda A Okiro, Thomas A Smith, and Lucy C Okell
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Public aspects of medicine ,RA1-1270 - Published
- 2017
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19. Modelling the drivers of the spread of Plasmodium falciparum hrp2 gene deletions in sub-Saharan Africa
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Oliver J Watson, Hannah C Slater, Robert Verity, Jonathan B Parr, Melchior K Mwandagalirwa, Antoinette Tshefu, Steven R Meshnick, and Azra C Ghani
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pfhrp2-deletion ,rapid diagnostic tests ,mathematical modelling ,mapping ,Medicine ,Science ,Biology (General) ,QH301-705.5 - Abstract
Rapid diagnostic tests (RDTs) have transformed malaria diagnosis. The most prevalent P. falciparum RDTs detect histidine-rich protein 2 (PfHRP2). However, pfhrp2 gene deletions yielding false-negative RDTs, first reported in South America in 2010, have been confirmed in Africa and Asia. We developed a mathematical model to explore the potential for RDT-led diagnosis to drive selection of pfhrp2-deleted parasites. Low malaria prevalence and high frequencies of people seeking treatment resulted in the greatest selection pressure. Calibrating our model against confirmed pfhrp2-deletions in the Democratic Republic of Congo, we estimate a starting frequency of 6% pfhrp2-deletion prior to RDT introduction. Furthermore, the patterns observed necessitate a degree of selection driven by the introduction of PfHRP2-based RDT-guided treatment. Combining this with parasite prevalence and treatment coverage estimates, we map the model-predicted spread of pfhrp2-deletion, and identify the geographic regions in which surveillance for pfhrp2-deletion should be prioritised.
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- 2017
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20. Role of mass drug administration in elimination of Plasmodium falciparum malaria: a consensus modelling study
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Oliver J Brady, DPhil, Hannah C Slater, PhD, Peter Pemberton-Ross, PhD, Edward Wenger, PhD, Richard J Maude, MD, Prof Azra C Ghani, PhD, Melissa A Penny, PhD, Jaline Gerardin, PhD, Prof Lisa J White, PhD, Nakul Chitnis, PhD, Ricardo Aguas, PhD, Simon I Hay, DSc, Prof David L Smith, PhD, Erin M Stuckey, PhD, Emelda A Okiro, PhD, Prof Thomas A Smith, PhD, and Dr Lucy C Okell, PhD
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Public aspects of medicine ,RA1-1270 - Abstract
Background: Mass drug administration for elimination of Plasmodium falciparum malaria is recommended by WHO in some settings. We used consensus modelling to understand how to optimise the effects of mass drug administration in areas with low malaria transmission. Methods: We collaborated with researchers doing field trials to establish a standard intervention scenario and standard transmission setting, and we input these parameters into four previously published models. We then varied the number of rounds of mass drug administration, coverage, duration, timing, importation of infection, and pre-administration transmission levels. The outcome of interest was the percentage reduction in annual mean prevalence of P falciparum parasite rate as measured by PCR in the third year after the final round of mass drug administration. Findings: The models predicted differing magnitude of the effects of mass drug administration, but consensus answers were reached for several factors. Mass drug administration was predicted to reduce transmission over a longer timescale than accounted for by the prophylactic effect alone. Percentage reduction in transmission was predicted to be higher and last longer at lower baseline transmission levels. Reduction in transmission resulting from mass drug administration was predicted to be temporary, and in the absence of scale-up of other interventions, such as vector control, transmission would return to pre-administration levels. The proportion of the population treated in a year was a key determinant of simulated effectiveness, irrespective of whether people are treated through high coverage in a single round or new individuals are reached by implementation of several rounds. Mass drug administration was predicted to be more effective if continued over 2 years rather than 1 year, and if done at the time of year when transmission is lowest. Interpretation: Mass drug administration has the potential to reduce transmission for a limited time, but is not an effective replacement for existing vector control. Unless elimination is achieved, mass drug administration has to be repeated regularly for sustained effect. Funding: Bill & Melinda Gates Foundation.
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- 2017
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21. Safety and effectiveness of His-bundle pacing and left bundle branch pacing (conduction system pacing) as a first option for cardiac pacing – results of a single-center
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C Slater, L E M Camanho, E B Saad, L A O Inacio Jr, L C Dias, G V Santos, and R Mourilhe-Rocha
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Cardiology and Cardiovascular Medicine - Abstract
Background Conduction system pacing (CSP) (His bundle pacing and left bundle pacing) is a group of techniques intended to achieve cardiac pacing with a narrow QRS complex through a lead directly inserted in conduction system structures. The safety and effectiveness of this technique are not yet fully understood. Purpose To describe the short-term implant findings and safety profile of CSP as a first option after 4 years in a single center. Methods In a period of 42 months, 214 patients were submitted to CSP as a first strategy to restore AV synchrony (pacemakers for AV block or sinus node dysfunction) or as a resynchronization (CRT) strategy (for patients with heart failure and bundle branch block). CSP lead was implanted in lieu of a conventional right ventricular lead in pacemaker cases, and in addition or in lieu of a coronary sinus lead, in CRT cases, depending on the technical and anatomical possibilities. Results The mean age was 76.7±16.4 years, 65% males. 162 patients implanted a CSP lead for a dual-chamber pacemaker, 3 patients for a single chamber pacemaker, 32 patients for CRT-D (CSP lead replacing the coronary sinus lead with a defibrillator), and 13 patients for an optimized CRT (CSP lead plus coronary sinus lead). In 16 patients (7.4%) the technique of choice was His bundle pacing, two of them presented with subacute elevated thresholds, requiring new lead implantation at the moment of generator pulse replacement. One patient submitted to left bundle branch pacing (0.4%) had subacute lead dislodgement, being submitted to lead revision. Four patients intended for CRT (1.8%) didn't meet the criteria for His bundle pacing or left bundle branch pacing, being submitted to conventional coronary sinus lead placement. There were 10 cases (4.6%) of confirmed lead perforation during the lead septum insertion, with prompt repositioning, all uneventful. No pericardium effusion related to lead perforation was observed. One patient (0.4%) had a pneumothorax, requiring chest tube drainage. Conclusion Conduction system pacing as a first strategy is a feasible, effective and safe technique, both for pacing and for resynchronization purposes, with a complication rate comparable to conventional implantation. Funding Acknowledgement Type of funding sources: None.
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- 2022
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22. Gender Discrimination and Sexual Harassment in a Department of Pediatrics
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Anne C. Slater, Anita A. Thomas, Linda Quan, Shaquita Bell, Miranda C. Bradford, Leslie Walker-Harding, and Abby R. Rosenberg
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Male ,Gender Equity ,Sexual Harassment ,Pregnancy ,Pediatrics, Perinatology and Child Health ,Sexism ,Humans ,Female ,Child ,Faculty ,Pediatrics - Abstract
The last substantial description of gender discrimination and harassment described in the journal Pediatrics was in 2019. It is unclear whether the field has made progress toward its goal of equity. We aimed to describe: (1) the recent gender-equity climate according to women and men faculty in the department of pediatrics at a single, large academic center, and (2) institutional efforts to address persistent gender discrimination and harassment. In late 2020, we distributed an anonymous survey to all department faculty that included demographic data, a modified version of the Overt Gender Discrimination at Work Scale, questions about experiences/witnessed discriminatory treatment and sexual harassment, and if those experiences negatively affected career advancement. Of 524 pediatrics faculty, 290 (55%) responded. Compared with men, women more commonly reported gender discrimination (50% vs. 4%, P < .01) and that their gender negatively affected their career advancement (50% vs 9%, P < .01). More than 50% of women reported discriminatory treatment at least annually and 38% recognized specific sexist statements; only 4% and 17% of men reported the same (P < .01 for both). We concluded that a disproportionately low number of male faculty recognized the harassment female faculty experienced. In the 18 months since, our department and university have made efforts to improve salary equity and parity in leadership representation, created an anonymous bias-reporting portal, mandated bias training, and implemented new benchmarks of “professionalism” that focus on diversity. Although we acknowledge that culture change will take time, we hope our lessons learned help promote gender equity in pediatrics more broadly.
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- 2022
23. Design and analysis of a 2-year parallel follow-up of repeated ivermectin mass drug administrations for control of malaria: Small sample considerations for cluster-randomized trials with count data
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Kathryn L. Colborn, Sangeeta Rao, Dexiang Gao, Sunil Parikh, John Kittelson, Brian D. Foy, Conner L. Jackson, and Hannah C Slater
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Drug ,Pediatrics ,medicine.medical_specialty ,media_common.quotation_subject ,Disease cluster ,01 natural sciences ,Article ,law.invention ,010104 statistics & probability ,03 medical and health sciences ,0302 clinical medicine ,Ivermectin ,Randomized controlled trial ,law ,Intervention (counseling) ,medicine ,Cluster Analysis ,Humans ,030212 general & internal medicine ,0101 mathematics ,Randomized Controlled Trials as Topic ,media_common ,Pharmacology ,business.industry ,Small sample ,General Medicine ,medicine.disease ,Malaria ,Research Design ,Sample Size ,Mass Drug Administration ,business ,Follow-Up Studies ,Count data ,medicine.drug - Abstract
Background: Cluster-randomized trials allow for the evaluation of a community-level or group-/cluster-level intervention. For studies that require a cluster-randomized trial design to evaluate cluster-level interventions aimed at controlling vector-borne diseases, it may be difficult to assess a large number of clusters while performing the additional work needed to monitor participants, vectors, and environmental factors associated with the disease. One such example of a cluster-randomized trial with few clusters was the “efficacy and risk of harms of repeated ivermectin mass drug administrations for control of malaria” trial. Although previous work has provided recommendations for analyzing trials like repeated ivermectin mass drug administrations for control of malaria, additional evaluation of the multiple approaches for analysis is needed for study designs with count outcomes. Methods: Using a simulation study, we applied three analysis frameworks to three cluster-randomized trial designs (single-year, 2-year parallel, and 2-year crossover) in the context of a 2-year parallel follow-up of repeated ivermectin mass drug administrations for control of malaria. Mixed-effects models, generalized estimating equations, and cluster-level analyses were evaluated. Additional 2-year parallel designs with different numbers of clusters and different cluster correlations were also explored. Results: Mixed-effects models with a small sample correction and unweighted cluster-level summaries yielded both high power and control of the Type I error rate. Generalized estimating equation approaches that utilized small sample corrections controlled the Type I error rate but did not confer greater power when compared to a mixed model approach with small sample correction. The crossover design generally yielded higher power relative to the parallel equivalent. Differences in power between analysis methods became less pronounced as the number of clusters increased. The strength of within-cluster correlation impacted the relative differences in power. Conclusion: Regardless of study design, cluster-level analyses as well as individual-level analyses like mixed-effects models or generalized estimating equations with small sample size corrections can both provide reliable results in small cluster settings. For 2-year parallel follow-up of repeated ivermectin mass drug administrations for control of malaria, we recommend a mixed-effects model with a pseudo-likelihood approximation method and Kenward–Roger correction. Similarly designed studies with small sample sizes and count outcomes should consider adjustments for small sample sizes when using a mixed-effects model or generalized estimating equation for analysis. Although the 2-year parallel follow-up of repeated ivermectin mass drug administrations for control of malaria is already underway as a parallel trial, applying the simulation parameters to a crossover design yielded improved power, suggesting that crossover designs may be valuable in settings where the number of available clusters is limited. Finally, the sensitivity of the analysis approach to the strength of within-cluster correlation should be carefully considered when selecting the primary analysis for a cluster-randomized trial.
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- 2021
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24. Repeat Ivermectin Mass Drug Administrations for Malaria Control II: Protocol for a Double-blind, Cluster-Randomized, Placebo-Controlled Trial for the Integrated Control of Malaria (Preprint)
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Brian D Foy, Anthony Some, Tereza Magalhaes, Lyndsey Gray, Sangeeta Rao, Emmanuel Sougue, Conner L Jackson, John Kittelson, Hannah C Slater, Teun Bousema, Ollo Da, A Gafar V Coulidiaty, McKenzie Colt, Martina Wade, Kacey Richards, A Fabrice Some, Roch K Dabire, and Sunil Parikh
- Abstract
BACKGROUND The gains made against malaria have stagnated since 2015, threatened further by increasing resistance to insecticides and antimalarials. Improvement in malaria control necessitates a multipronged strategy, which includes the development of novel tools. One such tool is mass drug administration (MDA) with endectocides, primarily ivermectin, which has shown promise in reducing malaria transmission through lethal and sublethal impacts on the mosquito vector. OBJECTIVE The primary objective of the study is to assess the impact of repeated ivermectin MDA on malaria incidence in children aged ≤10 years. METHODS Repeat Ivermectin MDA for Malaria Control II is a double-blind, placebo-controlled, cluster-randomized, and parallel-group trial conducted in a setting with intense seasonal malaria transmission in Southwest Burkina Faso. The study included 14 discrete villages: 7 (50%) randomized to receive standard measures (seasonal malaria chemoprevention [SMC] and bed net use for children aged 3 to 59 months) and placebo, and 7 (50%) randomized to receive standard measures and monthly ivermectin MDA at 300 μg/kg for 3 consecutive days, provided under supervision to all eligible village inhabitants, over 2 successive rainy seasons. Nonpregnant individuals >90 cm in height were eligible for ivermectin MDA, and cotreatment with ivermectin and SMC was not permitted. The primary outcome is malaria incidence in children aged ≤10 years, as assessed by active case surveillance. The secondary safety outcome of repeated ivermectin MDA was assessed through active and passive adverse event monitoring. RESULTS The trial intervention was conducted from July to November in 2019 and 2020, with additional sampling of humans and mosquitoes occurring through February 2022 to assess postintervention changes in transmission patterns. Additional human and entomological assessments were performed over the 2 years in a subset of households from 6 cross-sectional villages. A subset of individuals underwent additional sampling in 2020 to characterize ivermectin pharmacokinetics and pharmacodynamics. Analysis and unblinding will commence once the database has been completed, cleaned, and locked. CONCLUSIONS Our trial represents the first study to directly assess the impact of a novel approach for malaria control, ivermectin MDA as a mosquitocidal agent, layered into existing standard-of-care interventions. The study was designed to leverage the current SMC deployment infrastructure and will provide evidence regarding the additional benefit of ivermectin MDA in reducing malaria incidence in children. CLINICALTRIAL ClinicalTrials.gov NCT03967054; https://clinicaltrials.gov/ct2/show/NCT03967054; Pan African Clinical Trials Registry PACT201907479787308 INTERNATIONAL REGISTERED REPORT DERR1-10.2196/41197
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- 2022
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25. Evaluating the Performance of Malaria Genetics for Inferring Changes in Transmission Intensity Using Transmission Modeling
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Lucy C Okell, Hannah C Slater, Joel Hellewell, Hsiao-Han Chang, Azra C. Ghani, H. Juliette T. Unwin, Oliver J Watson, Robert Verity, Kirk A. Rockett, Christina Hubbart, Irene Omedo, Philip Bejon, Joaniter I. Nankabirwa, Robert W. Snow, Bryan Greenhouse, Abdisalan M. Noor, Wellcome Trust, The Royal Society, The Royal Society of Medicine, and Medical Research Council (MRC)
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Plasmodium ,Adolescent ,030231 tropical medicine ,malaria ,Sample (statistics) ,Mosquito Vectors ,Biology ,0601 Biochemistry and Cell Biology ,AcademicSubjects/SCI01180 ,law.invention ,03 medical and health sciences ,0302 clinical medicine ,0603 Evolutionary Biology ,law ,parasitic diseases ,Prevalence ,Genetics ,medicine ,Humans ,Uganda ,Transmission intensity ,Child ,Molecular Biology ,Discoveries ,Ecology, Evolution, Behavior and Systematics ,030304 developmental biology ,Evolutionary Biology ,0604 Genetics ,0303 health sciences ,Genetic diversity ,Models, Statistical ,AcademicSubjects/SCI01130 ,Genetic Variation ,modeling ,Statistical model ,medicine.disease ,Kenya ,Transmission (mechanics) ,Child, Preschool ,Superinfection ,Vector (epidemiology) ,surveillance ,Predictive power ,Malaria - Abstract
Substantial progress has been made globally to control malaria, however there is a growing need for innovative new tools to ensure continued progress. One approach is to harness genetic sequencing and accompanying methodological approaches as have been used in the control of other infectious diseases. However, to utilize these methodologies for malaria, we first need to extend the methods to capture the complex interactions between parasites, human and vector hosts, and environment, which all impact the level of genetic diversity and relatedness of malaria parasites. We develop an individual-based transmission model to simulate malaria parasite genetics parameterized using estimated relationships between complexity of infection and age from five regions in Uganda and Kenya. We predict that cotransmission and superinfection contribute equally to within-host parasite genetic diversity at 11.5% PCR prevalence, above which superinfections dominate. Finally, we characterize the predictive power of six metrics of parasite genetics for detecting changes in transmission intensity, before grouping them in an ensemble statistical model. The model predicted malaria prevalence with a mean absolute error of 0.055. Different assumptions about the availability of sample metadata were considered, with the most accurate predictions of malaria prevalence made when the clinical status and age of sampled individuals is known. Parasite genetics may provide a novel surveillance tool for estimating the prevalence of malaria in areas in which prevalence surveys are not feasible. However, the findings presented here reinforce the need for patient metadata to be recorded and made available within all future attempts to use parasite genetics for surveillance.
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- 2020
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26. Evaluating the Impact of Programmatic Mass Drug Administration for Malaria in Zambia Using Routine Incidence Data
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Mutinta Mudenda, John M. Miller, Laina D Mercer, Kafula Silumbe, Kammerle Schneider, Michael Hainsworth, Hannah C Slater, Elizabeth Chizema Kawesha, Caterina Guinovart, Maya Fraser, Adam Bennett, Busiku Hamainza, Hawela Moonga, and Thomas P. Eisele
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Impact evaluation ,030231 tropical medicine ,Malària ,Zambia ,Política sanitària ,Rate ratio ,law.invention ,Antimalarials ,03 medical and health sciences ,0302 clinical medicine ,Health facility ,law ,medicine ,Humans ,Immunology and Allergy ,030212 general & internal medicine ,Mass drug administration ,Generalized estimating equation ,business.industry ,Incidence ,Incidence (epidemiology) ,medicine.disease ,Malaria ,Infectious Diseases ,Transmission (mechanics) ,Mass Drug Administration ,Medical policy ,business ,Demography - Abstract
BACKGROUND NlmCategory: BACKGROUND content: In 2016, the Zambian National Malaria Elimination Centre started programmatic mass drug administration (pMDA) campaigns with dihydroartemisinin-piperaquine as a malaria elimination tool in Southern Province. Two rounds were administered, two months apart (coverage 70% and 57% respectively). We evaluated the impact of one year of pMDA on malaria incidence using routine data. - Label: METHODS NlmCategory: METHODS content: We conducted an interrupted time series with comparison group analysis on monthly incidence data collected at the health facility catchment area (HFCA) level, with a negative binomial model using generalized estimating equations. pMDA was conducted in HFCAs with greater than 50 cases/1,000 people/year. Ten HFCAs with incidence rates marginally above this threshold (pMDA group) were compared to 20 HFCAs marginally below (comparison group). - Label: RESULTS NlmCategory: RESULTS content: "The pMDA HFCAs saw a 46% greater decrease in incidence at the time of intervention than the comparison areas (incidence rate ratio: 0.536 [0.337-0.852]); however, incidence increased toward the end of the season. No HFCAs saw a transmission interruption." - Label: CONCLUSION NlmCategory: CONCLUSIONS content: pMDA, implemented during one year with imperfect coverage in low transmission areas with sub-optimal vector control coverage, significantly reduced incidence. However, elimination will require additional tools. Routine data are important resources for programmatic impact evaluations and should be considered for future analyses.
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- 2020
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27. Development and Validation of the Minnesota Inference Assessment
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Panayiota Kendeou, Jasmine Kim, Susan C. Slater, Kristen L. McMaster, Reese Butterfuss, and Okan Bulut
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business.industry ,05 social sciences ,Measure (physics) ,050301 education ,Inference ,Machine learning ,computer.software_genre ,050105 experimental psychology ,Education ,Comprehension ,General Health Professions ,Developmental and Educational Psychology ,0501 psychology and cognitive sciences ,Artificial intelligence ,business ,Psychology ,0503 education ,computer - Abstract
The overall aim of the current investigation was to develop and validate the initial version of the Minnesota Inference Assessment (MIA). MIA is a web-based measure of inference processes in Grades K–2. MIA leverages the affordances of different media to evaluate inference processes in a nonreading context, using age-appropriate fiction and nonfiction videos coupled with questioning. We evaluated MIA’s technical adequacy in a proof-of-concept study. Taken together, the results support the interpretation that MIA shows promise as a valid and reliable measure of inferencing in a nonreading context for students in Grades K–2. Future directions involve further development of multiple, parallel forms that can be used for progress monitoring in K–2.
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- 2020
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28. Investigating the Generalizability of Schema-Based Instruction Focused on Proportional Reasoning: A Multi-State Study
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Susan C. Slater, Soo-hyun Im, Asha K. Jitendra, Stacy R. Karl, and Michael R. Harwell
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Multi state ,business.industry ,Curran ,Proportional reasoning ,05 social sciences ,050301 education ,computer.software_genre ,Education ,Integrative data analysis ,Schema (psychology) ,Developmental and Educational Psychology ,Generalizability theory ,Artificial intelligence ,business ,0503 education ,computer ,Natural language processing - Abstract
This study used integrative data analysis (Curran & Hussong, 2009), which allows combining data from different studies, to examine the generalizability of a research-based mathematics program, sche...
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- 2020
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29. Mathematical Analysis of Melanocyte Patterns onDanio rerio
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Colleen M. Renier, Jennifer O. Liang, William M. Bauer, John Pastor, Cynthia A. Welsh, and Frances C. Slater
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0303 health sciences ,biology ,Danio ,Melanocyte ,biology.organism_classification ,Cell biology ,03 medical and health sciences ,0302 clinical medicine ,medicine.anatomical_structure ,embryonic structures ,medicine ,Animal Science and Zoology ,Zebrafish ,Developmental biology ,030217 neurology & neurosurgery ,030304 developmental biology ,Developmental Biology - Abstract
The study of zebrafish skin pattern development could lead to a better understanding of how these patterns are generated and how they evolved. To compare and contrast wild-type (WT) stripe...
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- 2020
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30. Diagnosing Fracture-Related Infections: Where Are We Now?
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H Claude Sagi, Julia C Slater, Federico Palacio Bedoya, Margaret V. Powers-Fletcher, and Madeleine C Stevenson
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0301 basic medicine ,Microbiology (medical) ,medicine.medical_specialty ,Arthritis, Infectious ,Consensus ,Prosthesis-Related Infections ,Prosthetic joint ,business.industry ,030106 microbiology ,MEDLINE ,Gold standard (test) ,Patient care ,United States ,03 medical and health sciences ,Clinical microbiology ,Fractures, Bone ,0302 clinical medicine ,Orthopedics ,medicine ,Humans ,Surgical Wound Infection ,030212 general & internal medicine ,Minireview ,Intensive care medicine ,business - Abstract
Accurate diagnosis of fracture-related infection (FRI) is critical for preventing poor outcomes such as loss of function or amputation. Due to the multiple variables associated with FRI, however, accurate diagnosis is challenging and complicated by a lack of standardized diagnostic criteria. Limitations with the current gold standard for diagnosis, which is routine microbiology culture, further complicate the diagnostic and management process. Efforts to optimize the process rely on a foundation of data derived from prosthetic joint infections (PJI), but differences in PJI and FRI make it clear that unique approaches for these distinct infections are required. A more concerted effort focusing on FRI has dominated more recent investigations and publications leading to a consensus definition by the American Orthopedics (AO) Foundation and the European Bone and Joint Infection Society (EBJIS). This has the potential to better standardize the diagnostic process, which will not only improve patient care but also facilitate more robust and reproducible research related to the diagnosis and management of FRI. The purpose of this minireview is to explore the consensus definition, describe the foundation of data supporting current FRI diagnostic techniques, and identify pathways for optimization of clinical microbiology-based strategies and data.
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- 2022
31. Locus-specific induction of gene expression from heterochromatin loci during cellular senescence
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Kosuke Tomimatsu, Dóra Bihary, Ioana Olan, Aled J. Parry, Stefan Schoenfelder, Adelyne S. L. Chan, Guy St. C. Slater, Yoko Ito, Peter J. Rugg-Gunn, Kristina Kirschner, Camino Bermejo-Rodriguez, Tomomi Seko, Hiroyuki Kugoh, Ken Shiraishi, Koji Sayama, Hiroshi Kimura, Peter Fraser, Masako Narita, Shamith A. Samarajiwa, Masashi Narita, Kirschner, Kristina [0000-0001-7607-8670], and Apollo - University of Cambridge Repository
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0303 health sciences ,Aging ,1.1 Normal biological development and functioning ,Inflammatory and immune system ,Neuroscience (miscellaneous) ,Stem Cell Research ,3105 Genetics ,03 medical and health sciences ,0302 clinical medicine ,030220 oncology & carcinogenesis ,FOS: Biological sciences ,Genetics ,1 Underpinning research ,Stem Cell Research - Nonembryonic - Non-Human ,Geriatrics and Gerontology ,030304 developmental biology ,31 Biological Sciences - Abstract
Cellular senescence is a fate-determined state, accompanied by reorganization of heterochromatin. While lineage-appropriate genes can be temporarily repressed through facultative heterochromatin, stable silencing of lineage-inappropriate genes often involves the constitutive heterochromatic mark, histone H3K9me3. The fate of these heterochromatic genes during the chromatin reorganization accompanying senescence is unclear. Here we show a small number of lineage-inappropriate genes are derepressed in senescent cells from H3K9me3 regions that gain open chromatin marks. DNA FISH experiments reveal that these gene loci, which are tightly condensed at the nuclear periphery in proliferative cells, are physically decompacted during senescence. Among these gene loci, NLRP3 is predominantly expressed in immune cells, such as macrophages, where it resides within an open topologically associated domain (TAD). In contrast, NLRP3 is derepressed in senescent fibroblasts, potentially due to the local disruption of the H3K9me3-rich TAD that contains it. The role of NLRP3 has been implicated in the amplification of inflammatory cytokine signalling in senescence and aging, underscoring the functional relevance of gene induction from ‘permissive’ H3K9me3 regions in senescent cells.
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- 2022
32. Electromagnetism
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John C. Slater, Nathaniel H. Frank
- Published
- 2012
33. On the Convergence of Nonlinear Modes of a Finite Element Model
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Ramesh Balagangadhar and Joseph C. Slater
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Physics ,QC1-999 - Abstract
Convergence of finite element models is generally realized via observation of mesh independence. In linear systems invariance of linear modes to further mesh refinement is often used to assess mesh independence. These linear models are, however, often coupled with nonlinear elements such as CFD models, nonlinear control systems, or joint dynamics. The introduction of a single nonlinear element can significantly alter the degree of mesh refinement necessary for sufficient model accuracy. Application of nonlinear modal analysis [1,2] illustrates that using linear modal convergence as a measure of mesh quality in the presence of nonlinearities is inadequate. The convergence of the nonlinear normal modes of a simply supported beam modeled using finite elements is examined. A comparison is made to the solution of Boivin, Pierre, and Shaw [3]. Both methods suffer from the need for convergence in power series approximations. However, the finite element modeling method introduces the additional concern of mesh independence, even when the meshing the linear part of the model unless p-type elements are used [4]. The importance of moving to a finite element approach for nonlinear modal analysis is the ability to solve problems of a more complex geometry for which no closed form solution exists. This case study demonstrates that a finite element model solution converges nearly as well as a continuous solution, and presents rough guidelines for the number of expansion terms and elements needed for various levels of solution accuracy. It also demonstrates that modal convergence occurs significantly more slowly in the nonlinear model than in the corresponding linear model. This illustrates that convergence of linear modes may be an inadequate measure of mesh independence when even a small part of a model is nonlinear.
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- 2008
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34. Model-Based Geostatistical Mapping of the Prevalence of Onchocerca volvulus in West Africa.
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Simon J O'Hanlon, Hannah C Slater, Robert A Cheke, Boakye A Boatin, Luc E Coffeng, Sébastien D S Pion, Michel Boussinesq, Honorat G M Zouré, Wilma A Stolk, and María-Gloria Basáñez
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Arctic medicine. Tropical medicine ,RC955-962 ,Public aspects of medicine ,RA1-1270 - Abstract
BACKGROUND:The initial endemicity (pre-control prevalence) of onchocerciasis has been shown to be an important determinant of the feasibility of elimination by mass ivermectin distribution. We present the first geostatistical map of microfilarial prevalence in the former Onchocerciasis Control Programme in West Africa (OCP) before commencement of antivectorial and antiparasitic interventions. METHODS AND FINDINGS:Pre-control microfilarial prevalence data from 737 villages across the 11 constituent countries in the OCP epidemiological database were used as ground-truth data. These 737 data points, plus a set of statistically selected environmental covariates, were used in a Bayesian model-based geostatistical (B-MBG) approach to generate a continuous surface (at pixel resolution of 5 km x 5km) of microfilarial prevalence in West Africa prior to the commencement of the OCP. Uncertainty in model predictions was measured using a suite of validation statistics, performed on bootstrap samples of held-out validation data. The mean Pearson's correlation between observed and estimated prevalence at validation locations was 0.693; the mean prediction error (average difference between observed and estimated values) was 0.77%, and the mean absolute prediction error (average magnitude of difference between observed and estimated values) was 12.2%. Within OCP boundaries, 17.8 million people were deemed to have been at risk, 7.55 million to have been infected, and mean microfilarial prevalence to have been 45% (range: 2-90%) in 1975. CONCLUSIONS AND SIGNIFICANCE:This is the first map of initial onchocerciasis prevalence in West Africa using B-MBG. Important environmental predictors of infection prevalence were identified and used in a model out-performing those without spatial random effects or environmental covariates. Results may be compared with recent epidemiological mapping efforts to find areas of persisting transmission. These methods may be extended to areas where data are sparse, and may be used to help inform the feasibility of elimination with current and novel tools.
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- 2016
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35. UK National DCD Heart Transplant Program - First Year Experience
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M. Berman, A. Ali, D. Macklam, D. Garcia Saez, A. Jothidasan, M. Husain, U. Stock, V. Mehta, R. Venkateswaran, P. Curry, S. Messer, M. Mukadam, J. Mascaro, S. Clarke, J. Baxter, S. Tsui, S. Large, M. Osman, P. Kaul, G. Boda, D. Jenkins, J. Simmonds, R. Quigley, J. Whitney, D. Gardiner, C. Watson, A. Rubino, I. Currie, J. Foley, A. Macleod, C. Slater, F. Marley, L. Downward, S. Rushton, L. Armstrong, L. Ayton, M. Ryan, M. Parker, S. Gibson, S. Spence, K. Quinn, S. Watson, and J. Forsythe
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Pulmonary and Respiratory Medicine ,Transplantation ,Surgery ,Cardiology and Cardiovascular Medicine - Published
- 2022
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36. 588 Utilizing a Quality Improvement Approach to Increase Compliance with Patient Positioning in the Burn Unit
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Catherine E Gallagher, Julia C Slater, and Elizabeth L Dale
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Rehabilitation ,Emergency Medicine ,Surgery - Abstract
Introduction Patient positioning, notably positioning patients in “anti-deformity positioning”, is a standard practice in burn rehabilitation as it assists with edema management, scar contracture prevention, and wound healing. Successfully and consistently providing proper positioning of burn patients requires the combined effort of the multi-disciplinary burn team. The primary goal at our center was to increase the frequency that patients were correctly positioned to over 90% at the time of random audits. Methods At a medium-sized, academic burn unit, once to twice weekly audits were conducted by burn lead therapists on the compliance of proper patient positioning over a 6-month period. Using this data as a trigger, a quality improvement project was designed using the PDSA (Plan-Do-Study-Act) cycle to help identify reasons behind lack of compliance. Surveys were distributed to the therapy and nursing staff to identify any barriers to care. Effects on positioning compliance post-intervention were monitored. Results In the 6 months prior to intervention, our patients were positioned correctly an average of 76% of the time. Therapy and nursing surveys identified the following barriers to care: Nursing needed more education on positioning, and the approach was too heavily reliant on nursing efforts alone. To address these barriers, therapists provided education to both day and night shift nurses, communicated daily about positioning expectations, shifted the project from a nursing approach to a multidisciplinary approach, and made changes in therapy workflow. Immediately following the intervention, the compliance rates were 91% for the first month and 85% for the second month. Conclusions Coordinating efforts of the entire burn team improves consistency for positioning in burn patients. Utilizing the PDSA cycle allowed us to identify areas for improvement and to develop appropriate interventions aimed at both increased education for nursing staff and workflow improvements for our therapists. Following the completion of our interventions we were able to obtain an immediate improvement in our compliance with proper positioning of burn patients.
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- 2022
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37. Developing an interactive software application to support young children’s inference-making
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Reese Butterfuss, Panayiota Kendeou, Mary Jane White, Cristina Umana, Jasmine Kim, Britta Bresina, Kyle Wagner, Susan C. Slater, and Kristen L. McMaster
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Linguistics and Language ,Literature and Literary Theory ,Human–computer interaction ,Early literacy ,Computer science ,Intervention (counseling) ,Inference ,Interactive software ,Language and Linguistics ,Education - Published
- 2019
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38. Improving student learning of ratio, proportion, and percent: A replication study of schema-based instruction
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Susan C. Slater, Soo-hyun Im, Michael R. Harwell, Stacy R. Karl, and Asha K. Jitendra
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Teaching method ,Proportional reasoning ,05 social sciences ,050301 education ,PsycINFO ,Education ,Schema (psychology) ,Developmental and Educational Psychology ,Mathematics education ,Racial differences ,Faculty development ,Student learning ,Psychology ,0503 education ,School learning - Abstract
The purpose of this replication study was to provide replication evidence not currently available of the effects of a research-based mathematics program, schema-based instruction, on the mathematical problem-solving performance of 7th-grade students. The replication was implemented in 36 schools in 5 districts; 59 mathematics teachers and their students (N = 1,492) participated in the study. Multilevel hierarchical linear analyses revealed statistically significant differences between conditions on proximal and distal measures of mathematics problem solving, with effects sizes similar to those reported in Jitendra et al. (2015). (PsycINFO Database Record (c) 2019 APA, all rights reserved)
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- 2019
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39. In-Situ Residual Tracking in Reduced Order Modelling
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Joseph C. Slater, Chris L. Pettit, and Philip S. Beran
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Physics ,QC1-999 - Abstract
Proper orthogonal decomposition (POD) based reduced-order modelling is demonstrated to be a weighted residual technique similar to Galerkin's method. Estimates of weighted residuals of neglected modes are used to determine relative importance of neglected modes to the model. The cumulative effects of neglected modes can be used to estimate error in the reduced order model. Thus, once the snapshots have been obtained under prescribed training conditions, the need to perform full-order simulations for comparison is eliminates. This has the potential to allow the analyst to initiate further training when the reduced modes are no longer sufficient to accurately represent the predominant phenomenon of interest. The response of a fluid moving at Mach 1.2 above a panel to a forced localized oscillation of the panel at and away from the training operating conditions is used to demonstrate the evaluation method.
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- 2002
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40. Performance and utility of more highly sensitive malaria rapid diagnostic tests
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Martin De Smet, Xavier C. Ding, Hawela Moonga, Gonzalo J. Domingo, Daniel J. Bridges, Adam Bennett, Laurence Slutsker, Sabine Dittrich, Hannah C Slater, Neil J. Saad, and Sophia Knudson
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Plasmodium falciparum ,Protozoan Proteins ,Antigens, Protozoan ,Computational biology ,Infectious and parasitic diseases ,RC109-216 ,Rapid diagnostic test ,Sensitivity and Specificity ,Pregnancy ,parasitic diseases ,Medicine ,Humans ,Malaria, Falciparum ,health care economics and organizations ,Malaria diagnosis ,business.industry ,Diagnostic Tests, Routine ,Diagnostic test ,medicine.disease ,equipment and supplies ,Highly sensitive ,Malaria ,Infectious Diseases ,Cross-Sectional Studies ,HS-RDT ,Female ,Cross-sectional surveys ,business ,Research Article - Abstract
BackgroundA new more highly sensitive rapid diagnostic test (HS-RDT) forPlasmodium falciparummalaria (Alere™/Abbott Malaria Ag P.f RDT [05FK140], now calledNxTek™Eliminate Malaria Ag Pf) was launched in 2017. The test has already been used in many research studies in a wide range of geographies and use cases.MethodsIn this study, we collate all published and available unpublished studies that use the HS-RDT and assess its performance in (i) prevalence surveys, (ii) clinical diagnosis, (iii) screening pregnant women, and (iv) active case detection. Two individual-level data sets from asymptomatic populations are used to fit logistic regression models to estimate the probability of HS-RDT positivity based on histidine-rich protein 2 (HRP2) concentration and parasite density. The performance of the HS-RDT in prevalence surveys is estimated by calculating the sensitivity and positive proportion in comparison to polymerase chain reaction (PCR) and conventional malaria RDTs.ResultsWe find that across 18 studies, in prevalence surveys, the mean sensitivity of the HS-RDT is estimated to be 56.1% (95% confidence interval [CI] 46.9–65.4%) compared to 44.3% (95% CI 32.6–56.0%) for a conventional RDT (co-RDT) when using nucleic acid amplification techniques as the reference standard. In studies where prevalence was estimated using both the HS-RDT and a co-RDT, we found that prevalence was on average 46% higher using a HS-RDT compared to a co-RDT. For use in clinical diagnosis and screening pregnant women, the HS-RDT was not significantly more sensitive than a co-RDT.ConclusionsOverall, the evidence presented here suggests that the HS-RDT is more sensitive in asymptomatic populations and could provide a marginal improvement in clinical diagnosis and screening pregnant women. Although the HS-RDT has limited temperature stability and shelf-life claims compared to co-RDTs, there is no evidence to suggest, given this test has the same cost as current RDTs, it would have any negative impacts in terms of malaria misdiagnosis if it were widely used in all four population groups explored here.
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- 2021
41. Modelling Co-Infection with Malaria and Lymphatic Filariasis.
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Hannah C. Slater, Manoj Gambhir, Paul E. Parham, and Edwin Michael
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- 2013
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42. Global patterns of submicroscopic Plasmodium falciparum malaria infection: insights from a systematic review and meta-analysis of population surveys
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Teun Bousema, Charles Whittaker, Hannah C Slater, Azra C. Ghani, Lucy C Okell, Chris Drakeley, Rebecca K Nash, Medical Research Council (MRC), and The Royal Society
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Adult ,Microbiology (medical) ,medicine.medical_specialty ,TRANSMISSION ,Plasmodium falciparum ,Population ,MOSQUITOS ,Microbiology ,law.invention ,Pregnancy ,law ,Virology ,Epidemiology ,medicine ,Humans ,EPIDEMIOLOGY ,Malaria, Falciparum ,Child ,Infected population ,education ,ELIMINATION ,Parasite density ,education.field_of_study ,Science & Technology ,biology ,Bayes Theorem ,Articles ,biology.organism_classification ,medicine.disease ,Malaria ,Cross-Sectional Studies ,Infectious Diseases ,Transmission (mechanics) ,lnfectious Diseases and Global Health Radboud Institute for Health Sciences [Radboudumc 4] ,Meta-analysis ,Female ,Life Sciences & Biomedicine ,Demography - Abstract
Contains fulltext : 238223.pdf (Publisher’s version ) (Open Access) BACKGROUND: Adoption of molecular techniques to detect Plasmodium falciparum infection has revealed many previously undetected (by microscopy) yet transmissible low-density infections. The proportion of these infections is typically highest in low transmission settings, but drivers of submicroscopic infection remain unclear. Here, we updated a previous systematic review of asexual P falciparum prevalence by microscopy PCR in the same population. We aimed to explore potential drivers of submicroscopic infection and to identify the locations where submicroscopic infections are most common. METHODS: In this systematic review and meta-analysis we searched PubMed and Web of Science from Jan 1, 2010, until Oct 11, 2020, for cross-sectional studies reporting data on asexual P falciparum prevalence by both microscopy and PCR. Surveys of pregnant women, surveys in which participants had been chosen based on symptoms or treatment, or surveys that did not involve a population from a defined location were excluded. Both the number of individuals tested and the number of individuals who tested positive by microscopy or PCR, or both, for P falciparum infection were extracted. Bayesian regression modelling was used to explore determinants of the size of the submicroscopic reservoir including geographical location, seasonality, age, methodology, and current or historical patterns of transmission. FINDINGS: Of 4893 identified studies, we retained 121 after screening and removal of duplicates. 45 studies from a previous systematic review were included giving 166 studies containing 551 cross-sectional survey microscopy and PCR prevalence pairs. Our results show that submicroscopic infections predominate in low-transmission settings across all regions, but also reveal marked geographical variation, with the proportion of infections that are submicroscopic being highest in South American surveys and lowest in west African surveys. Although current transmission levels partly explain these results, we find that historical transmission intensity also represents a crucial determinant of the size of the submicroscopic reservoir, as does the demographic structure of the infected population (with submicroscopic infection more likely to occur in adults than in children) and the PCR or microscopy methodology used. We also observed a small yet significant influence of seasonality, with fewer submicroscopic infections observed in the wet season than the dry season. Integrating these results with estimates of infectivity in relation to parasite density suggests the contribution of submicroscopic infections to transmission across different settings is likely to be highly variable. INTERPRETATION: Significant variation in the prevalence of submicroscopic infection exists even across settings characterised by similar current levels of transmission. These differences in submicroscopic epidemiology potentially warrant different approaches to targeting this infected subgroup across different settings to eliminate malaria. FUNDING: Bill & Melinda Gates Foundation, The Royal Society, and the UK Medical Research Council.
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- 2021
43. Multidrug Resistant Epididymitis Progressing to Testicular Infarct and Orchiectomy
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Nicholas J. Farber, Rick C. Slater, and Jodi K. Maranchie
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Diseases of the genitourinary system. Urology ,RC870-923 - Abstract
Global testicular infarction is a rare sequela of infectious epididymitis, with few reports in the urologic literature since the introduction of fluoroquinolones in the late 1980s. Ischemia occurs secondary to inflammation and edema of the spermatic cord with compression of arterial flow. We report a case of multidrug resistant epididymitis following prostate biopsy that progressed to global testicular infarction requiring orchiectomy. This case highlights the fact that epididymitis does not always follow an indolent pathway to resolution. Progression of pain should prompt early imaging and intervention. It further highlights the potential urologic consequences of the rising prevalence of multidrug resistant bowel flora in the United States, which will increasingly influence the management of presumed uncomplicated epididymitis, whether being primary or postprocedural.
- Published
- 2013
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44. Secreted Protein Acidic and Cysteine Rich Matricellular Protein is Enriched in the Bioactive Fraction of the Human Vascular Pericyte Secretome
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Yue Gu, Rajesh Katare, Giuseppe Mangialardi, Antonio Paolo Beltrami, Paolo Madeddu, Valeria Vincenza Alvino, Kate J. Heesom, Massimo Caputo, William Cathery, Elisa Avolio, and Sadie C. Slater
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0301 basic medicine ,Stromal cell ,Receptor, Platelet-Derived Growth Factor alpha ,Physiology ,Clinical Biochemistry ,Myocardial Infarction ,Biochemistry ,Extracellular matrix ,03 medical and health sciences ,Paracrine signalling ,Growth factor receptor ,Downregulation and upregulation ,Cell Movement ,medicine ,Creatine Kinase, MB Form ,Humans ,Myocytes, Cardiac ,Osteonectin ,Molecular Biology ,General Environmental Science ,Cell Proliferation ,Secretome ,030102 biochemistry & molecular biology ,Cell growth ,Chemistry ,Matricellular protein ,Endothelial Cells ,Cell Biology ,Cell Hypoxia ,Cell biology ,Extracellular Matrix ,Collagen Type I, alpha 1 Chain ,030104 developmental biology ,medicine.anatomical_structure ,Gene Expression Regulation ,General Earth and Planetary Sciences ,Pericyte ,Pericytes - Abstract
Aims: To ascertain if human pericytes produce SPARC (acronym for Secreted Protein Acidic and Cysteine Rich), a matricellular protein implicated in the regulation of cell proliferation, migration, and cell-matrix interactions; clarify if SPARC expression in cardiac pericytes is modulated by hypoxia; and determine the functional consequences of SPARC silencing. Results: Starting from the recognition that the conditioned media (CM) of human pericytes promote proliferation and migration of cardiac stromal cells, we screened candidate mediators by mass-spectrometry analysis. Of the 14 high-confidence proteins (
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- 2020
45. Human adventitial pericytes secrete bioactive factors exerting distinct biological effects on cardiac cells: hints for cardiac repair
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Paolo Madeddu, Gianni D Angelini, Kate J. Heesom, Elisa Avolio, Valeria Vincenza Alvino, Sadie C. Slater, Giuseppe Mangialardi, and Antonio Paolo Beltrami
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Vascular Biology and Physiology ,Basic Science ,Basic science ,business.industry ,Cardiac repair ,Medicine ,Secretion ,Cardiology and Cardiovascular Medicine ,business ,Cell biology - Abstract
BackgroundPericytes are attracting much attention as potential candidates for successful cell therapy of myocardial ischaemia. Intramyocardially delivered adventitial pericytes (APCs) secrete paracrine factors which stimulate angiogenesis and recruitment of cardiac stromal cells, reduce fibrosis and promote cardiomyocyte proliferation and viability. However, factors responsible for these biological effects have not been elucidated yet.PurposeTo exploit the components of APC secretome exerting a biological effect on cardiac cells with the aim to discover new druggable targets with potential therapeutic activity.Methods and resultsAPCs were derived from saphenous veins of adult patients (n=13, 68±11 yrs, all with coronary artery disease - CAD). The APC-conditioned medium (CM) stimulated the proliferation of human iPS-derived cardiomyocytes compared with unconditioned medium (UCM) (EdU incorporation, 1.3-fold increases, P=0.004). Stimulation with APC-CM increased the number of mitotic figures in cardiomyocytes (Aurora B, 1.5-fold increases compared to UCM, P=0.002). Furthermore, APC-CM abrogated the hypoxia-induced apoptosis in cardiomyocytes (2-fold increase in Caspase 3/7 activity in hypoxic cells exposed to UCM compared to normoxic cells, P=0.002). We also found that APC-CM stimulates the migration of human cardiac stromal cells (CSCs) obtained from healthy donors (n=6, 54±11 yrs) in both a transwell and scratch migration assays (n=6, P30KDa. The pro-migratory fractions of the APC-CM obtained from size exclusion chromatography underwent mass spectrometry analysis (n=3 APCs). This identified 14 proteins uniquely present in the pro-migratory fractions. The two most relevant candidates were SPARC and TGFBI, both confirmed by ELISA. Intriguingly, the recombinant SPARC and TGFBI failed to reproduce the biological effect of APC-CM on CSC migration, suggesting that the secreted proteins may carry unique post-translational modifications not found in synthetic peptides. Further analyses are being carried out to reveal the biological properties of the endogenous SPARC and TGFBI.ConclusionsThis study suggests a fascinating approach based on the use of the active component of the APC-CM as a surrogate of APC therapy. If the biological properties of the cellular proteins will be successfully reproduced in synthetic peptides in vitro, this innovative approach may extend the benefits of APC therapy to all those patients with CAD for whom cell therapy is not an available option.
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- 2020
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46. Human adventitial pericytes provide a unique source of anti-calcific cells for cardiac valve engineering: Role of microRNA-132-3p
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Gianni D Angelini, Domenico Bruno, Ashton Faulkner, Daniel Baz-Lopez, Eva Jover, Emanuela Pisanu, Michele Carrabba, Yue Gu, Paolo Madeddu, William Cathery, Elisa Avolio, Sadie C. Slater, and Marco Fagnano
- Subjects
0301 basic medicine ,Bristol Heart Institute ,Cell ,Biochemistry ,pericytes ,calcification ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Tissue engineering ,Downregulation and upregulation ,Osteogenesis ,Physiology (medical) ,microRNA ,medicine ,Humans ,Antagomir ,Cells, Cultured ,business.industry ,Mesenchymal stem cell ,Endothelial Cells ,Cell Differentiation ,medicine.disease ,prosthetic valve ,microRNAs ,Cell biology ,MicroRNAs ,030104 developmental biology ,medicine.anatomical_structure ,HEK293 Cells ,chemistry ,valvular heart disease ,tissue engineering ,Aortic Valve ,Cellularization ,mesenchymal stromal cells ,business ,Pericytes ,030217 neurology & neurosurgery ,Calcification - Abstract
Aims: Tissue engineering aims to improve the longevity of prosthetic heart valves. However, the optimal cell source has yet to be determined. This study aimed to establish a mechanistic rationale supporting the suitability of human adventitial pericytes (APCs).Methods and Results: APCs were immunomagnetically sorted from saphenous vein leftovers of patients undergoing coronary artery bypass graft surgery and antigenically characterized for purity. Unlike bone marrow-derived mesenchymal stromal cells (BM-MSCs), APCs were resistant to calcification and delayed osteochondrogenic differentiation upon high phosphate (HP) induction, as assessed by cytochemistry and expression of osteogenic markers. Moreover, glycolysis was activated during osteogenic differentiation of BM-MSCs, whereas APCs showed no increase in glycolysis upon HP challenge. The microRNA-132-3p (miR-132), a known inhibitor of osteogenesis, was found constitutively expressed by APCs and upregulated following HP stimulation. The anti-calcific role of miR-132 was further corroborated by in silico analysis, luciferase assays in HEK293 cells, and transfecting APCs with miR-132 agomir and antagomir, followed by assessment of osteochondrogenic markers. Interestingly, treatment of swine cardiac valves with APC-derived conditioned medium conferred them with resistance to HP-induced osteogenesis, with this effect being negated when using the medium of miR-132-silenced APCs. Additionally, as an initial bioengineering step, APCs were successfully engrafted onto pericardium sheets, where they proliferated and promoted aortic endothelial cells attraction, a process mimicking valve endothelialization. Conclusions: Human APCs are resistant to calcification compared with BM-MSCs and convey the anti-calcific phenotype to heart valves through miR-132. These findings may open new important avenues for prosthetic valve cellularization.
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- 2020
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47. Assessing the Quality and Reliability of Patient Information Regarding First-Aid for Acute Burns on YouTube
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Julia C Slater, Maleeh Effendi, David Parizh, and Elizabeth L. Dale
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Adult ,Specialty ,Video Recording ,030204 cardiovascular system & hematology ,computer.software_genre ,03 medical and health sciences ,0302 clinical medicine ,Patient Education as Topic ,Medical advice ,Ease of Access ,Medicine ,First Aid ,Humans ,Social media ,030212 general & internal medicine ,Health Education ,Medical education ,Internet ,Burn therapy ,Consumer Health Information ,Online presence management ,business.industry ,Information Dissemination ,Rehabilitation ,Content creation ,Emergency Medicine ,Surgery ,business ,Burns ,computer ,Social Media ,First aid - Abstract
Given ever increasing ease of access to technology, the majority of adults first turn to the internet for medical advice. The world wide web is filled with user-generated content within multiple social media platforms that lack a governing body to validate the information’s accuracy and reliability. The authors performed a qualitative review of first-aid burn resources available on YouTube using two validated scales: Modified Discern and Global Quality Scale. A search was conducted using the term “burn treatment” on September 18, 2019. Of 120 reviewed videos, 59 met their inclusion criteria. 36% (n = 21) of the speakers had formal medical training, with only 12% (n = 7) identified as burn care professionals. The mean views originating from nonmedical speakers (162,675) were more than eight times that originating from burn centers (14,975). The quality of the videos was compared by video source, speaker, and specialty. Burn centers had the highest Modified Discern and Global Quality Scale scores, 2.91 and 2.86, respectively (P < .05). Additionally, the authors were able to demonstrate that there was a statistically significant higher quality of videos when the speaker was a burn care professional or had formal medical training. Unfortunately, their review demonstrated that videos originating from hospital systems and burn centers made up a minority of the online media content. These results illustrate an opportunity for improvement by way of increased content creation to bolster the online presence of the burn community and provide patients with more accurate information.
- Published
- 2020
48. The potential public health consequences of COVID-19 on malaria in Africa
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Fatima Al Ali, Marc Baguelin, Edward Knock, Charles Whittaker, Azra C. Ghani, John A. Lees, Alexandra B. Hogan, Audu B. Mohammad, Arran Hamlet, Mara D. Kont, Lilith K Whittles, Thomas S. Churcher, Nnenna Ogbulafor, Sangeeta N. Bhatia, Bhargavi Rao, Matthew Cairns, Patrick G T Walker, Lucy C Okell, Jamilu Nikau, Perpetua Uhomoibhi, Joseph D. Challenger, Ibrahim Maikore, Okefu Oyale Okoko, Oliver J Watson, Hannah C Slater, Peter Winskill, Ellie Sherrard-Smith, Robert Verity, Ben Lambert, Imperial College LOndon, Bill & Melinda Gates Foundation, Medical Research Council (MRC), and Wellcome Trust
- Subjects
0301 basic medicine ,medicine.medical_specialty ,Biochemistry & Molecular Biology ,Coronavirus disease 2019 (COVID-19) ,TRANSMISSION ,Immunology ,CHILDREN ,Research & Experimental Medicine ,CHINA ,General Biochemistry, Genetics and Molecular Biology ,law.invention ,03 medical and health sciences ,Health services ,0302 clinical medicine ,Malaria transmission ,CLINICAL CHARACTERISTICS ,law ,Environmental health ,parasitic diseases ,medicine ,11 Medical and Health Sciences ,Science & Technology ,PLASMODIUM-FALCIPARUM ,Public health ,Cell Biology ,General Medicine ,medicine.disease ,Case management ,3. Good health ,030104 developmental biology ,Transmission (mechanics) ,Geography ,Medicine, Research & Experimental ,030220 oncology & carcinogenesis ,Malaria control ,BURDEN ,Life Sciences & Biomedicine ,Malaria - Abstract
The burden of malaria is heavily concentrated in sub-Saharan Africa (SSA) where cases and deaths associated with COVID-19 are rising1. In response, countries are implementing societal measures aimed at curtailing transmission of SARS-CoV-22,3. Despite these measures, the COVID-19 epidemic could still result in millions of deaths as local health facilities become overwhelmed4. Advances in malaria control this century have been largely due to distribution of long-lasting insecticidal nets (LLINs)5, with many SSA countries having planned campaigns for 2020. In the present study, we use COVID-19 and malaria transmission models to estimate the impact of disruption of malaria prevention activities and other core health services under four different COVID-19 epidemic scenarios. If activities are halted, the malaria burden in 2020 could be more than double that of 2019. In Nigeria alone, reducing case management for 6 months and delaying LLIN campaigns could result in 81,000 (44,000–119,000) additional deaths. Mitigating these negative impacts is achievable, and LLIN distributions in particular should be prioritized alongside access to antimalarial treatments to prevent substantial malaria epidemics. Transmission dynamics models of COVID-19 and malaria reveal how different scenarios of COVID-19 spread and varying levels of interruption to antimalarial programs could result in increased deaths in sub-Saharan Africa.
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- 2020
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49. MicroRNA-24-3p Targets Notch and Other Vascular Morphogens to Regulate Post-ischemic Microvascular Responses in Limb Muscles
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Kerrie L. Ford, Andrea Caporali, Maryam Anwar, Graciela B. Sala-Newby, Marco Meloni, Micol Marchetti, Costanza Emanueli, Sadie C. Slater, and Ayman Al Haj Zen
- Subjects
Male ,Notch ,Angiogenesis ,Notch signaling pathway ,Biology ,Catalysis ,Mural cell ,Article ,lcsh:Chemistry ,Inorganic Chemistry ,angiogenesis ,Mice ,Ischemia ,microRNA ,Human Umbilical Vein Endothelial Cells ,Animals ,Humans ,Physical and Theoretical Chemistry ,Receptor, Notch1 ,miR-24-3p ,Muscle, Skeletal ,lcsh:QH301-705.5 ,Molecular Biology ,3' Untranslated Regions ,Spectroscopy ,beta Catenin ,Receptors, Notch ,Organic Chemistry ,GATA2 ,Wnt signaling pathway ,Cell Differentiation ,Extremities ,General Medicine ,Transfection ,β-catenin ,Hedgehog signaling pathway ,endothelial cells ,Computer Science Applications ,Cell biology ,MicroRNAs ,lcsh:Biology (General) ,lcsh:QD1-999 ,limb ischemia - Abstract
MicroRNAs (miRs) regulate complex processes, including angiogenesis, by targeting multiple mRNAs. miR-24-3p-3p directly represses eNOS, GATA2, and PAK4 in endothelial cells (ECs), thus inhibiting angiogenesis during development and in the infarcted heart. miR-24-3p is widely expressed in cardiovascular cells, suggesting that it could additionally regulate angiogenesis by acting on vascular mural cells. Here, we have investigated: 1) new miR-24-3p targets, 2) the expression and the function of miR-24-3p in human vascular ECs, 3) the impact of miR-24-3p inhibition in the angiogenesis reparative response to limb ischemia in mice. Using bioinformatics target prediction platforms and 3&prime, UTR luciferase assays, we newly identified Notch1 and its Delta-like ligand 1 (Dll1) to be directly targeted by miR-24-3p. miR-24-3p was expressed in human ECs and pericytes cultured under normal conditions. Exposure to hypoxia increased miR-24-3p in ECs but not in pericytes. Transfection with a miR-24-3p precursor (pre-miR-24-3p) increased miR-24-3p expression in ECs, reducing the cell survival, proliferation, and angiogenic capacity. Opposite effects were caused by miR-24-3p inhibition. The anti-angiogenic action of miR-24-3p overexpression could be prevented by simultaneous adenovirus (Ad)-mediated delivery of constitutively active Notch intracellular domain (NICD) into cultured ECs. We next demonstrated that reduced Notch signalling contributes to the anti-angiogenic effect of miR-24-3p in vitro. In a mouse unilateral limb ischemia model, local miR-24-3p inhibition (by adenovirus-mediated miR-24-3p decoy delivery) restored endothelial Notch signalling and increased capillary density. However, the new vessels appeared disorganised and twisted, worsening post-ischemic blood perfusion recovery. To better understand the underpinning mechanisms, we widened the search for miR-24-3p target genes, identifying several contributors to vascular morphogenesis, such as several members of the Wingless (Wnt) signalling pathway, &beta, catenin signalling components, and VE-cadherin, which synergise to regulate angiogenesis, pericytes recruitment to neoformed capillaries, maturation, and stabilization of newly formed vessels. Among those, we next focussed on &beta, catenin to demonstrate that miR-24-3p inhibition reduces &beta, catenin expression in hypoxic ECs, which is accompanied by reduced adhesion of pericytes to ECs. In summary, miR-24-3p differentially targets several angiogenesis modulators and contributes to autonomous and non-autonomous EC crosstalk. In ischemic limbs, miR-24-3p inhibition increases the production of dysfunctional microvessels, impairing perfusion. Caution should be observed in therapeutic targeting of miR-24-3p.
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- 2020
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50. Strain Gage Ramifications on Mistuning in As-Manufactured Models and Experimental Testing
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Joseph C. Slater, Joseph A. Beck, Daniel L. Gillaugh, Jeffrey M. Brown, and Alex A. Kaszynski
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Materials science ,business.industry ,Mechanical Engineering ,Energy Engineering and Power Technology ,Aerospace Engineering ,Structural engineering ,02 engineering and technology ,Mistuning ,021001 nanoscience & nanotechnology ,Finite element method ,Experimental testing ,020303 mechanical engineering & transports ,Fuel Technology ,0203 mechanical engineering ,Nuclear Energy and Engineering ,Traveling wave ,business ,0210 nano-technology ,Gas compressor ,Strain gauge - Abstract
Blade-mounted strain gages are vital during rig and engine development to ensure safe engine operation. However, they also enable a change in dynamics of integrally bladed rotors (IBRs). State-of-the-art IBR dynamic response predictions are accomplished using as-manufactured models (AMMs) generated via optical topography measurements and mesh morphing. Two AMM finite element models (FEMs) are created of a 20-bladed IBR. One FEM has no strain gages present, where the second FEM includes strain gages on six blades. Traditionally, strain gages and lead wires are treated as the same material property as the IBR itself. It will be shown that the inclusion of strain gages in AMM's using this method changes the IBR's predicted mistuning. An alternative AMM approach is developed that changes the material properties of the finite elements attributed to the strain gages. The predicted mistuning for each AMM is accomplished using the fundamental mistuning model identification (FMM ID), where the predicted mistuning will be compared to both traveling wave excitation (TWE) experiments and a rotating, single stage compressor rig. Findings show mistuning predictions of the nonstrain gaged AMM compare far better to the experiments compared to the inclusion of the strain gages in the AMM. Additionally, altering material properties of the strain gages in the AMM improve mistuning prediction compared to treating the strain gages as the parent IBR material. Therefore, AMM should be acquired using clean, nonstrain gaged rotors or the material properties of strain gaged elements need to be altered to more accurately model the component.
- Published
- 2020
- Full Text
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