Search

Background: Understanding the knowledge, perception and attitudes towards Ebola vaccines is an important factor in ensuring future use of these vaccines. A qualitative methods study embedded in an Ebola vaccine immunogenicity and safety trial (NCT04028349) was conducted to explore the knowledge and perceptions of healthcare (HCWs) and frontline workers (FLWs), about Ebola vaccines and their willingness to participate or recommend participation in Uganda., Method: We carried out focus group discussions and semi-structured interviews before and after vaccination, with 70 HCWs and FLWs who consented to participate in the trial, and in the qualitative component, from August to September 2019. Data were analysed using thematic content analysis., Results: Respondents showed good knowledge about Ebola and the vaccines in general, and had wide access to information through several channels, including the study team. On prevention, particular attention was given to effective communication within health facilities. Misconceptions were mainly around route of transmission, animal origin and types of vaccines. Previous fears were based on rumours circulating in the community, mainly about the presence of the virus in the vaccine, side effects and intention to harm (e.g. by "the whites"), ultimately insisting on transparency, trust and involvement of local leaders. Acceptability of participation was motivated by the need to protect self and others, and the willingness to advance research. Majority were willing to recommend participation to their community., Conclusions: Overall, information sharing leads to a better understanding and acceptance of vaccine trials and a positive vaccination experience can be a deciding factor in the acceptance of others. Particular attention should be paid to involving the community in addressing misconceptions and fears, while ensuring that participants have access to vaccination sites in terms of transport, and that they are properly accommodated at the study site including staying for a reasonable period of time., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier India Pvt Ltd. All rights reserved.)

Background: Antibiotic resistance is a significant public health problem and is responsible for high mortality in children and new-borns. Strengthening the rational use of antibiotics and improving the quality and access to existing antibiotics are important factors in the fight against antibiotic resistance. This study aims to provide knowledge on the use of antibiotics in children in resource-limited countries in order to identify problems and possible avenues for improvement of antibiotics use., Methods: We conducted a retrospective study in July 2020 and collected quantitative clinical and therapeutic data on antibiotic prescriptions between January and December 2019 in 4 hospitals or health centres in both Uganda and Niger, respectively from January to December 2019. Semi-structured interviews and focus groups were conducted among healthcare personnel and carers for children under 17 years of age, respectively., Results: A total of 1,622 children in Uganda and 660 children in Niger (mean age of 3.9 years (SD 4.43)) who received at least one antibiotic were included in the study. In hospital settings, 98.4 to 100% of children prescribed at least one antibiotic received at least one injectable antibiotic. Most hospitalized children received more than one antibiotic in both Uganda (52.1%) and Niger (71.1%). According to the WHO-AWaRe index, the proportion of prescriptions of antibiotics belonging to the Watch category was 21.8% (432/1982) in Uganda and 32.0% (371/1158) in Niger. No antibiotics from the Reserve category were prescribed. Health care provider's prescribing practices are rarely guided by microbiological analyses. Prescribers are faced with numerous constraints, such as lack of standard national guidelines, unavailability of essential antibiotics at the level of hospital pharmacies, the limited financial means of the families, and pressure to prescribe antibiotics from caregivers as well as from drug company representatives. The quality of some antibiotics provided by the National Medical Stores to the public and private hospitals has been questioned by some health professionals. Self-medication is a widespread practice for the antibiotic treatment of children for economic and access reasons., Conclusion: The study findings indicate that an intersection of policy, institutional norms and practices including individual caregiver or health provider factors, influence antibiotic prescription, administration and dispensing practices., (© 2023. The Author(s).)

Background: The most common form of neuronal ceroid lipofuscinosis (NCL) is juvenile CLN3 disease (JNCL), a currently incurable neurodegenerative disorder caused by mutations in the CLN3 gene. Based on our previous work and on the premise that CLN3 affects the trafficking of the cation-independent mannose-6 phosphate receptor and its ligand NPC2, we hypothesised that dysfunction of CLN3 leads to the aberrant accumulation of cholesterol in the late endosomes/lysosomes (LE/Lys) of JNCL patients' brains., Methods: An immunopurification strategy was used to isolate intact LE/Lys from frozen autopsy brain samples. LE/Lys isolated from samples of JNCL patients were compared with age-matched unaffected controls and Niemann-Pick Type C (NPC) disease patients. Indeed, mutations in NPC1 or NPC2 result in the accumulation of cholesterol in LE/Lys of NPC disease samples, thus providing a positive control. The lipid and protein content of LE/Lys was then analysed using lipidomics and proteomics, respectively., Findings: Lipid and protein profiles of LE/Lys isolated from JNCL patients were profoundly altered compared to controls. Importantly, cholesterol accumulated in LE/Lys of JNCL samples to a comparable extent than in NPC samples. Lipid profiles of LE/Lys were similar in JNCL and NPC patients, except for levels of bis(monoacylglycero)phosphate (BMP). Protein profiles detected in LE/Lys of JNCL and NPC patients appeared identical, except for levels of NPC1., Interpretation: Our results support that JNCL is a lysosomal cholesterol storage disorder. Our findings also support that JNCL and NPC disease share pathogenic pathways leading to aberrant lysosomal accumulation of lipids and proteins, and thus suggest that the treatments available for NPC disease may be beneficial to JNCL patients. This work opens new avenues for further mechanistic studies in model systems of JNCL and possible therapeutic interventions for this disorder., Funding: San Francisco Foundation., Competing Interests: Declaration of interests The authors declare no competing financial interests., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

The late endosome/lysosome (LE/Lys) lipid bis(monoacylglycero)phosphate (BMP) plays major roles in cargo sorting and degradation, regulation of cholesterol and intercellular communication and has been linked to viral infection and neurodegeneration. Although BMP was initially described over fifty years ago, the enzymes regulating its synthesis remain unknown. The first step in the BMP biosynthetic pathway is the conversion of phosphatidylglycerol (PG) into lysophosphatidylglycerol (LPG) by a phospholipase A2 (PLA2) enzyme. Here we report that this enzyme is lysosomal PLA2 (LPLA2). We show that LPLA2 is sufficient to convert PG into LPG in vitro. We show that modulating LPLA2 levels regulates BMP levels in HeLa cells, and affects downstream pathways such as LE/Lys morphology and cholesterol levels. Finally, we show that in a model of Niemann-Pick disease type C, overexpressing LPLA2 alleviates the LE/Lys cholesterol accumulation phenotype. Altogether, we shed new light on BMP biosynthesis and contribute tools to regulate BMP-dependent pathways., (© 2023. The Author(s).)

Excess brain cholesterol is strongly implicated in the pathogenesis of Alzheimer's disease (AD). Here we evaluated how the presence of a cholesterol-binding site (CBS) in the transmembrane and juxtamembrane regions of the amyloid precursor protein (APP) regulates its processing. We generated nine point mutations in the APP gene, changing the charge and/or hydrophobicity of the amino-acids which were previously shown as part of the CBS. Most mutations triggered a reduction of amyloid-β peptides Aβ40 and Aβ42 secretion from transiently transfected HEK293T cells. Only the mutations at position 28 of Aβ in the APP sequence resulted in a concomitant significant increase in the production of shorter Aβ peptides. Mass spectrometry (MS) confirmed the predominance of Aβx-33 and Aβx-34 with the APP K28A mutant. The enzymatic activity of α-, β-, and γ-secretases remained unchanged in cells expressing all mutants. Similarly, subcellular localization of the mutants in early endosomes did not differ from the APP WT protein. A transient increase of plasma membrane cholesterol enhanced the production of Aβ40 and Aβ42 by APP WT , an effect absent in APP K28A mutant. Finally, WT but not CBS mutant Aβ derived peptides bound to cholesterol-rich exosomes. Collectively, the present data revealed a major role of juxtamembrane amino acids of the APP CBS in modulating the production of toxic Aβ species. More generally, they underpin the role of cholesterol in the pathophysiology of AD., (© 2022. The Author(s).)

Down Syndrome (DS), caused by triplication of human chromosome 21 (Hsa21) is the most common form of intellectual disability worldwide. Recent progress in healthcare has resulted in a dramatic increase in the lifespan of individuals with DS. Unfortunately, most will develop Alzheimer's disease like dementia (DS-AD) as they age. Understanding similarities and differences between DSAD and the other forms of the disease - i.e., late-onset AD (LOAD) and autosomal dominant AD (ADAD) - will provide important clues for the treatment of DS-AD. In addition to the APP gene that codes the precursor of the main component of amyloid plaques found in the brain of AD patients, other genes on Hsa21 are likely to contribute to disease initiation and progression. This review focuses on SYNJ1, coding the phosphoinositide phosphatase synaptojanin 1 (SYNJ1). First, we highlight the function of SYNJ1 in the brain. We then summarize the involvement of SYNJ1 in the different forms of AD at the genetic, transcriptomic, proteomic and neuropathology levels in humans. We further examine whether results in humans correlate with what has been described in murine and cellular models of the disease and report possible mechanistic links between SYNJ1 and the progression of the disease. Finally, we propose a set of questions that would further strengthen and clarify the role of SYNJ1 in the different forms of AD., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Background: The risk of healthcare-associated infections is exacerbated by poor hygiene practices in health care facilities and can contribute to increased patient morbidity and mortality. In low-income settings, caregivers play a key role in maintaining proper hygiene during inpatient stays. We aimed to explore caregivers' knowledge, perceptions and practices related to hospital hygiene in a rural, sub-Saharan African setting., Methods: We conducted an exploratory qualitative study among caregivers of children admitted to an inpatient therapeutic feeding center in Madarounfa, Niger. Individual interviews with 28 caregivers of hospitalized children were conducted to explore their knowledge, perceptions and practices of hygiene in the health facility., Findings: Caregivers described a broad understanding of hygiene and reported knowledge of its importance in the hospital, particularly to prevent disease transmission and protect child health. Hygiene was perceived as a collective rather than individual responsibility. Caregivers reported on the poor hygiene practice of others and cited a lack of space and hygiene materials as barriers to correct hygiene practice. Caregivers described educational sessions and informal sharing with other caregivers as tools to gain knowledge and improve practice., Conclusion: This exploratory study is unique in describing the perspective of caregivers in a low-resource hospital setting, a group often underrepresented when designing health interventions to improve hospital hygiene. Our findings suggest a strong knowledge of hospital hygiene among caregivers in this setting, with positive perception of its importance in health promotion. Poor individual practice was reported but may be improved through additional education and provision of hygiene materials., (© 2021 The Authors.)

Objective: We present the results of a cross-cultural validation of the Mental Health Global State (MHGS) scale for adults and adolescents (<14 years old)., Methods: We performed two independent studies using mixed methods among 103 patients in Hebron, Occupied Palestinian Territories and 106 in Cauca, Colombia. The MHGS was analyzed psychometrically, sensitivity and specificity, ability to detect clinically meaningful change, compared to the Clinical Global Impression-Severity scale (CGI-S). Principal component analysis was used to reduce the number of questions after data collection., Results: The scale demonstrated good internal consistency, with a Cronbach alpha score of 0.80 in both settings. Test retest reliability was high, ICC 0.70 (95% CI [0.41-0.85]) in Hebron and 0.87 (95% CI [0.76-0.93]) in Cauca; inter-rater reliability was 0.70 (95% CI [0.42-0.85]) in Hebron and 0.76 (95% CI [0.57-0.88]) in Cauca. Psychometric properties were also good, and the tool demonstrated a sensitivity of 85% in Hebron and 100% in Cauca, with corresponding specificity of 80% and 79%, when compared to CGI-S., Conclusions: The MHGS showed promising results to assess global mental health thereby providing an additional easy to use tool in humanitarian interventions. Additional work should focus on validation in at least one more context, to adhere to best practices in transcultural validation., (© 2020 The Authors. International Journal of Methods in Psychiatric Research published by John Wiley & Sons Ltd.)

Background: Nutritional supplements are used for preventing and treating childhood malnutrition. While there is a growing body of evidence on product efficacy, less emphasis has been placed on how they are perceived and used at the household level. Here, we report on the intrahousehold management of three different supplements (Ready to Use Supplementary food (RUSF), medium quantity lipid-based nutrient supplements (LNS-MQ) and Super Cereal Plus (SC+)) in the region of Maradi (Niger). The main objective of this study was to describe the use, consumption and perception of the three different nutritional products at the household level., Methods: The study was conducted in the Madarounfa district in the region of Maradi (February - March 2012). Female caregivers were purposely selected from eligible households and invited to participate. Data were collected through focus group discussion and interviews and were analyzed using thematic content analysis., Results: In total, 114 caregivers participated. Three major themes were initially identified and included preparation and conservation; consumption and sharing practices as well as perception of impact. The data showed good acceptance at the household level including perceived benefits for the target children, health improvement, prevention of illness and malnutrition. Sharing and gifting at both household and community level were also reported., Conclusions: Caregivers displayed positive perceptions toward the investigated supplements. Patterns of actual management should be considered in the design, implementation, monitoring and evaluation of future programs., Competing Interests: Competing interestsThe authors declare they have no competing interest., (© The Author(s). 2020.)

Background: Healthcare-associated infections pose a major, yet often preventable risk to patient safety. Poor hand hygiene among healthcare personnel and unsanitary hospital environments may contribute to this risk in low-income settings. We aimed to describe hand hygiene behaviour and environmental contamination by season in a rural, sub-Saharan African hospital setting., Methods: We conducted a concurrent triangulation mixed-methods study combining three types of data at a hospital in Madarounfa, Niger. Hand hygiene observations among healthcare personnel during two seasons contributed quantitative data describing hand hygiene frequency and its variability in relation to seasonal changes in caseload. Semistructured interviews with healthcare personnel contributed qualitative data on knowledge, attitudes and barriers to hand hygiene. Biweekly environmental samples evaluated microbial contamination from October 2016 to December 2017. Triangulation identified convergences, complements and contradictions across results., Results: Hand hygiene compliance, or the proportion of actions (handrubbing or handwashing) performed out of all actions required, was low (11% during non-peak and 36% during peak caseload seasons). Interviews with healthcare personnel suggesting good general knowledge of hand hygiene contradicted the low hand hygiene compliance. However, compliance by healthcare activity was convergent with poor knowledge of precise hand hygiene steps and the motivation to prevent personal acquisition of infection identified during interviews. Contamination of environmental samples with gram-negative bacilli was high (45%), with the highest rates of contamination observed during the peak caseload season., Conclusion: Low hand hygiene compliance coupled with high contamination rates of hospital environments may increase the risk of hospital-acquired infections in sub-Saharan African settings., (© The Author(s) 2019. Published by Oxford University Press.)

Background: In low-resource settings, the lack of mental health professionals and cross-culturally validated screening instruments complicates mental health care delivery. This is especially the case for very young children. Here, we aimed to develop and cross-culturally validate a simple and rapid tool, the PSYCa 6-36, that can be administered by non-professionals to screen for psychological difficulties among children aged six to 36 months., Methods: A primary validation of the PSYCa 6-36 was conducted in Kenya (n = 319 children aged 6 to 36 months; 2014), followed by additional validations in Kenya (n = 215; 2014) Cambodia (n = 189; 2015) and Uganda (n = 182; 2016). After informed consent, trained interviewers administered the PSYCa 6-36 to caregivers participating in the study. We assessed the psychometric properties of the PSYCa 6-36 and external validity was assessed by comparing the results of the PSYCa 6-36 against a clinical global impression severity [CGIS] score rated by an independent psychologist after a structured clinical interview with each participant., Results: The PSYCa 6-36 showed satisfactory psychometric properties (Cronbach's alpha > 0.60 in Uganda and > 0.70 in Kenya and Cambodia), temporal stability (intra-class correlation coefficient [ICC] > 0.8), and inter-rater reliability (ICC from 0.6 in Uganda to 0.8 in Kenya). Psychologists identified psychological difficulties (CGIS score > 1) in 11 children (5.1%) in Kenya, 13 children (8.7%) in Cambodia and 15 (10.5%) in Uganda, with an area under the receiver operating characteristic curve of 0.65 in Uganda and 0.80 in Kenya and Cambodia., Conclusions: The PSYCa 6-36 allowed for rapid screening of psychological difficulties among children aged 6 to 36 months among the populations studied. Use of the tool also increased awareness of children's psychological difficulties and the importance of early recognition to prevent long-term consequences. The PSYCa 6-36 would benefit from further use and validation studies in popula`tions with higher prevalence of psychological difficulties.

The phosphoinositide phosphatase synaptojanin 1 (SYNJ1) is a key regulator of synaptic function. We first tested whether SYNJ1 contributes to phenotypic variations in familial Alzheimer's disease (FAD) and show that SYNJ1 polymorphisms are associated with age of onset in both early- and late-onset human FAD cohorts. We then interrogated whether SYNJ1 levels could directly affect memory. We show that increased SYNJ1 levels in autopsy brains from adults with Down syndrome (DS/AD) are inversely correlated with synaptophysin levels, a direct readout of synaptic integrity. We further report age-dependent cognitive decline in a mouse model overexpressing murine Synj1 to the levels observed in human sporadic AD, triggered through hippocampal hyperexcitability and defects in the spatial reproducibility of place fields. Taken together, our findings suggest that SYNJ1 contributes to memory deficits in the aging hippocampus in all forms of AD., (Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.)

The size of all cells, from bacteria to vertebrates, is proportional to the growth rate set by nutrient availability, but the underlying mechanisms are unknown. Here, we show that nutrients modulate cell size and growth rate via the TORC2 signaling network in budding yeast. An important function of the TORC2 network is to modulate synthesis of ceramide lipids, which play roles in signaling. TORC2-dependent control of ceramide signaling strongly influences both cell size and growth rate. Thus, cells that cannot make ceramides fail to modulate their growth rate or size in response to changes in nutrients. PP2A associated with the Rts1 regulatory subunit (PP2A Rts1 ) is embedded in a feedback loop that controls TORC2 signaling and helps set the level of TORC2 signaling to match nutrient availability. Together, the data suggest a model in which growth rate and cell size are mechanistically linked by ceramide-dependent signals arising from the TORC2 network., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Objective: The current qualitative study aimed to identify gender, social and cultural influences on the management and use of unconditional cash transfers as part of a prospective intervention study in Niger., Design: In February to March 2012, focus group discussions and semi-structured individual interviews were conducted with female caregivers of children aged 6 to 23 months who received unconditional cash transfers. Discussion and interview transcripts were analysed using content thematic analysis., Setting: The study was conducted in the Madarounfa district in Maradi region of Niger., Subjects: Among forty-eight intervention villages, fourteen were selected for the qualitative study. Participants were randomly selected from eligible households., Results: In total, 124 women participated in focus group discussions or interviews. The majority reported giving the cash transfer to the male head of household who primarily managed cash at the household level. Women reported using a portion of the money to purchase foods for the target child. Feeding the household was the primary use of the cash transfer, followed by health care, clothing, gifts or ceremonies., Conclusions: Gender, social and cultural norms influenced management and usage of the cash transfer at the household level. The results highlight the importance of integrating gender-sensitive indicators into interventions. Information and awareness sessions should be an integral component of large-scale distributions with a special emphasis on gender equality and the importance of women's empowerment to improve agriculture and family health.

Small GTPases play a critical role in membrane traffic. Among them, Arf6 mediates transport to and from the plasma membrane, as well as phosphoinositide signalling and cholesterol homeostasis. Here we delineate the molecular basis for the link between Arf6 and cholesterol homeostasis using an inducible knockout (KO) model of mouse embryonic fibroblasts (MEFs). We find that accumulation of free cholesterol in the late endosomes/lysosomes of Arf6 KO MEFs results from mistrafficking of Niemann-Pick type C protein NPC2, a cargo of the cation-independent mannose-6-phosphate receptor (CI-M6PR). This is caused by a selective increase in an endosomal pool of phosphatidylinositol-4-phosphate (PI4P) and a perturbation of retromer, which controls the retrograde transport of CI-M6PR via sorting nexins, including the PI4P effector SNX6. Finally, reducing PI4P levels in KO MEFs through independent mechanisms rescues aberrant retromer tubulation and cholesterol mistrafficking. Our study highlights a phosphoinositide-based mechanism for control of cholesterol distribution via retromer.

Mental health care for infants and young children is often greatly limited in low-resource settings. The purpose of this study was to describe maternal perception of emotional difficulties of preschool children in a rural area of Niger (Maradi). In this context, both mental health awareness and services were scarce. This research was part of a larger cross-cultural validation study of a screening tool for psychological difficulties in children aged 3 to 6 years old. Data collection included group discussion and individual interviews. A total of 10 group interviews and 83 individual interviews were conducted. The results highlight mothers' perceptions concerning their children's psychological difficulties. Sleep difficulties were considered significant by the mothers and were used often as an entry point for further discussion of concerns. Peer and sibling relationships, separation anxiety, and reactions to difficult events were also described. Identification of mothers' perceptions of children's main difficulties through a mixed-method approach shows promise as a way to inform interventions to provide culturally appropriate care for children in need., (© The Author(s) 2016.)

Background: Detection of children's psychological difficulties in crises and low resource settings is challenged by the lack of a validated, rapid and simple tool. We present the results of two confirmatory validations of the Psychological Screening for Young Children aged 3 to 6 years (PSYCa 3-6) scale., Methods: We performed cross-cultural validations, assessing the performance of the scale in different contexts. These were conducted in Mathare, Nairobi, Kenya and Buenaventura, Colombia between December 2009 and February 2012. External validity was assessed comparing the PSYCa 3-6 against a clinical interview and the Clinical Global Impression Severity scale (CGI)., Results: A total of 160 mothers or caregivers of children 3 to 6 years old in Mathare and 148 in Buenaventura were included in the study. Both demonstrated good concurrent validity (Buenaventura ρ=0.49, p<0.0001; Mathare ρ=0.41, p<0.0001). Inter-rater reliability was found to be acceptable in Buenaventura (intraclass correlation [ICC]=0.69 [0.4-0.84]) and high in Mathare (0.87 [0.75-0.94])., Conclusions: As shown by its validation in diverse contexts, use in other populations may help improve the delivery of mental health care to children in crises and low-resource settings. Additional research on the design and delivery of intervention models for crises remains essential., (© The Author 2015. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Abnormalities in neuronal cholesterol homeostasis have been suspected or observed in several neurodegenerative disorders including Alzheimer's disease, Parkinson's disease and Huntington's disease. However, it has not been demonstrated whether an increased abundance of cholesterol in neurons in vivo contributes to neurodegeneration. To address this issue, we used RNA interference methodology to inhibit the expression of cholesterol 24-hydroxylase, encoded by the Cyp46a1 gene, in the hippocampus of normal mice. Cholesterol 24-hydroxylase controls cholesterol efflux from the brain and thereby plays a major role in regulating brain cholesterol homeostasis. We used an adeno-associated virus vector encoding short hairpin RNA directed against the mouse Cyp46a1 mRNA to decrease the expression of the Cyp46a1 gene in hippocampal neurons of normal mice. This increased the cholesterol concentration in neurons, followed by cognitive deficits and hippocampal atrophy due to apoptotic neuronal death. Prior to neuronal death, the recruitment of the amyloid protein precursor to lipid rafts was enhanced leading to the production of β-C-terminal fragment and amyloid-β peptides. Abnormal phosphorylation of tau and endoplasmic reticulum stress were also observed. In the APP23 mouse model of Alzheimer's disease, the abundance of amyloid-β peptides increased following inhibition of Cyp46a1 expression, and neuronal death was more widespread than in normal mice. Altogether, these results suggest that increased amounts of neuronal cholesterol within the brain may contribute to inducing and/or aggravating Alzheimer's disease., (© The Author (2015). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Elevations in neuronal cholesterol have been associated with several degenerative diseases. An enhanced excitability and synchronous firing in surviving neurons are among the sequels of neuronal death in these diseases and also in some epileptic syndromes. Here, we attempted to increase neuronal cholesterol levels, using a short hairpin RNA to suppress expression of the enzyme cytochrome P450 family 46, subfamily A, polypeptide 1 gene (CYP46A1). This protein hydroxylates cholesterol and so facilitates transmembrane extrusion. A short hairpin RNA CYP46A1construction coupled to the adeno-associated virus type 5 was injected focally and unilaterally into mouse hippocampus. It was selectively expressed first in neurons of the cornu ammonis (hippocampus) (CA)3a region. Cytoplasmic and membrane cholesterol increased, and the neuronal soma volume increased and then decreased before pyramidal cells died. As CA3a pyramidal cells died, interictal electroencephalographic (EEG) events occurred during exploration and non-rapid eye movement sleep. With time, neuronal death spread to involve pyramidal cells and interneurons of the CA1 region. CA1 neuronal death was correlated with a delayed local expression of phosphorylated tau. Astrocytes were activated throughout the hippocampus and microglial activation was specific to regions of neuronal death. CA1 neuronal death was correlated with distinct aberrant EEG activity. During exploratory behaviour and rapid eye movement sleep, EEG oscillations at 7-10 Hz (theta) could accelerate to 14-21 Hz (beta) waves. They were accompanied by low-amplitude, high-frequency oscillations of peak power at ~300 Hz and a range of 250-350 Hz. Although episodes of EEG acceleration were not correlated with changes in exploratory behaviour, they were followed in some animals by structured seizure-like discharges. These data strengthen links between increased cholesterol, neuronal sclerosis and epileptic behaviour., (© 2015 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.)

Background: It is suspected that excess of brain cholesterol plays a role in Alzheimer's disease (AD). Membrane-associated cholesterol was shown to be increased in the brain of individuals with sporadic AD and to correlate with the severity of the disease. We hypothesized that an increase of membrane cholesterol could trigger sporadic AD early phenotypes., Results: We thus acutely loaded the plasma membrane of cultured neurons with cholesterol to reach the 30% increase observed in AD brains. We found changes in gene expression profiles that are reminiscent of early AD stages. We also observed early AD cellular phenotypes. Indeed we found enlarged and aggregated early endosomes using confocal and electron microscopy after immunocytochemistry. In addition amyloid precursor protein vesicular transport was inhibited in neuronal processes, as seen by live-imaging. Finally transient membrane cholesterol loading lead to significantly increased amyloid-β42 secretion., Conclusions: Membrane cholesterol increase in cultured neurons reproduces most early AD changes and could thus be a relevant model for deciphering AD mechanisms and identifying new therapeutic targets.

Setting: Armenia, a country with a high prevalence of drug-resistant tuberculosis (DR-TB)., Objective: To identify factors related to default from DR-TB treatment in Yerevan., Design: Using a retrospective cohort design, we compared defaulters with patients who were cured, completed or failed treatment. Patients who initiated DR-TB treatment from 2005 to 2011 were included in the study. A qualitative survey was conducted including semi-structured interviews with defaulters and focus group discussions with care providers., Results: Of 381 patients, 193 had achieved treatment success, 24 had died, 51 had failed treatment and 97 had defaulted. The number of drugs to which the patient was resistant at admission (aRR 1.16, 95%CI 1.05-1.27), the rate of treatment interruption based on patient's decision (aRR 1.03, 95%CI 1.02-1.05), the rate of side effects (aRR 1.18, 95%CI 1.09-1.27), and absence of culture conversion during the intensive phase (aRR 0.47, 95%CI 0.31-0.71) were independently associated with default from treatment. In the qualitative study, poor treatment tolerance, a perception that treatment was inefficient, lack of information, incorrect perception of being cured, working factors and behavioural problems were factors related to treatment default., Conclusion: In addition to economic reasons, poor tolerance of and poor response to treatment were the main factors associated with treatment default.

Although cholesterol has been involved in the pathophysiology of Alzheimer disease (AD), its distribution in the cerebral cortex over the course of AD is unknown. We describe an original method to quantify cholesterol distribution using time-of-flight secondary ion mass spectrometry imaging. Cholesterol was unevenly distributed along the cortical thickness, being more abundant close to the white matter, in both control and AD cases. However, the mean cholesterol signal was significantly higher in the lower half of the cortex in AD samples compared to controls. This increase, when converted into cortical layers, was statistically significant for layers III and IV and did not reach significance in layers V + VI, the variability being too high at the interface between grey and white matter. The density of neurofibrillary tangles and of senile plaques was not statistically linked to the abundance of cholesterol. Cholesterol overload thus appears a new and independent alteration of AD cerebral cortex. The structure in which cholesterol accumulates and the mechanism of this accumulation remain to be elucidated.

Few studies have looked at consumption of Ready-to-Use-Supplementary-Foods (RUSFs) during a nutritional emergency. Here, we describe the use and acceptability of RUSF within households in four districts of the region of Maradi, Niger during large scale preventive distributions with RUSF in 2010 targeted at children 6-35months of age. Our study comprised both quantitative and qualitative components to collect detailed information and to allow in-depth interviews. We performed a cross-sectional survey in 16 villages between two monthly distributions of RUSF (October-November 2010). All households with at least one child who received RUSF were included and a total of 1842 caregivers were interviewed using a structured questionnaire. Focus groups and individual interviews of 128 caregivers were conducted in eight of the selected villages. On average, 24.7% of households reported any sharing of RUSF within the household. Sharing practices outside the household remained rare. Most of the sharing reported occurred among children under 5years of age living in the household. On average, 91% of caregivers in all districts rated the child's appreciation of the products as good or very good. Program planning may need to explicitly accounting for the sharing of products among children under 5 within household., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Background: The mental health needs of young children in humanitarian contexts often remain unaddressed. The lack of a validated, rapid and simple tool for screening combined with few mental health professionals able to accurately diagnose and provide appropriate care mean that young children remain without care. Here, we present the results of the principle cross-cultural validation of the "Psychological Screening for Young Children aged 3 to 6" (PSYCAa3-6). The PSYCa 3-6 is a simple scale for children 3 to 6 years old administered by non-specialists, to screen young children in crises and thereby refer them to care if needed., Methods: This study was conducted in Maradi, Niger. The scale was translated into Hausa, using corroboration of independent translations. A cross-cultural validation was implemented using quantitative and qualitative methods. A random sample of 580 mothers or caregivers of children 3 to 6 years old were included. The tool was psychometrically examined and diagnostic properties were assessed comparing the PSYCa 3-6 against a clinical interview as the gold standard., Results: The PSYCa 3-6 Hausa version demonstrated good concurrent validity, as scores correlated with the gold standard and the Clinical Global Impression Severity Scale (CGI-S) [rho = 0.41, p-value = 0.00]. A reduction procedure was used to reduce the scale from 40 to 22 items. The test-retest reliability of the PSYCa 3-6 was found to be high (ICC 0.81, CI95% [0.68; 0.89]). In our sample, although not the purpose of this study, approximately 54 of 580 children required subsequent follow-up with a psychologist., Conclusions: To our knowledge, this is the first validation of a screening scale for children 3 to 6 years old with a cross-cultural validation component, for use in humanitarian contexts. The Hausa version of the PSYCa 3-6 is a reliable and a valuable screening tool for psychological distress. Further studies to replicate our findings and additional validations of the PSYCa 3-6 in other populations may help improve the delivery of mental health care to children.

In the past fifteen years the notion that cell membranes are not homogenous and rely on microdomains to exert their functions has become widely accepted. Lipid rafts are membrane microdomains enriched in cholesterol and sphingolipids. They play a role in cellular physiological processes such as signalling, and trafficking but are also thought to be key players in several diseases including viral or bacterial infections and neurodegenerative diseases. Yet their existence is still a matter of controversy. Indeed, lipid raft size has been estimated to be around 20 nm, far under the resolution limit of conventional microscopy (around 200 nm), thus precluding their direct imaging. Up to now, the main techniques used to assess the partition of proteins of interest inside lipid rafts were Detergent Resistant Membranes (DRMs) isolation and co-patching with antibodies. Though widely used because of their rather easy implementation, these techniques were prone to artefacts and thus criticized. Technical improvements were therefore necessary to overcome these artefacts and to be able to probe lipid rafts partition in living cells. Here we present a method for the sensitive analysis of lipid rafts partition of fluorescently-tagged proteins or lipids in the plasma membrane of living cells. This method, termed Fluorescence Correlation Spectroscopy (FCS), relies on the disparity in diffusion times of fluorescent probes located inside or outside of lipid rafts. In fact, as evidenced in both artificial membranes and cell cultures, probes would diffuse much faster outside than inside dense lipid rafts. To determine diffusion times, minute fluorescence fluctuations are measured as a function of time in a focal volume (approximately 1 femtoliter), located at the plasma membrane of cells with a confocal microscope (Fig. 1). The auto-correlation curves can then be drawn from these fluctuations and fitted with appropriate mathematical diffusion models. FCS can be used to determine the lipid raft partitioning of various probes, as long as they are fluorescently tagged. Fluorescent tagging can be achieved by expression of fluorescent fusion proteins or by binding of fluorescent ligands. Moreover, FCS can be used not only in artificial membranes and cell lines but also in primary cultures, as described recently. It can also be used to follow the dynamics of lipid raft partitioning after drug addition or membrane lipid composition change.

Classical FRET (Förster Resonance Energy Transfer) using two fluorescent labels (one for the donor and another one for the acceptor) is not efficient for studying the homodimerization of a protein as only half of the homodimers formed can be identified by this technique. We thus resorted to homoFRET detected by time-resolved Fluorescence Anisotropy IMaging (tr-FAIM). To specifically image the plasma membrane of living cells, an original combination of tr-FAIM and Total Internal Reflection Fluorescence Lifetime Imaging Microscope (TIRFLIM) was implemented. The correcting factor accounting for the depolarization due to the high numerical aperture (NA) objective, mandatory for TIRF microscopy, was quantified on fluorescein solutions and on HEK293 cells expressing enhanced Green Fluorescence Protein (eGFP). Homodimerization of Amyloid Precursor Protein (APP), a key mechanism in the etiology of Alzheimer's disease, was measured on this original set-up. We showed, both in epifluorescence and under TIRF excitation, different energy transfer rates associated with the homodimerization of wild type APP-eGFP or of a mutated APP-eGFP, which forms constitutive dimers. This original set-up thus offers promising prospects for future studies of protein homodimerization in living cells in control and pathological conditions.

Muscarinic toxins isolated from the venom of Dendroaspis snakes may interact with a high affinity, large selectivity and various functional properties with muscarinic receptors. Therefore, these toxins are invaluable tools for studying the physiological role, molecular functioning and structural organization of the five subtypes of these G-Protein Coupled Receptors. We review the data on the most relevant results dealing with the isolation/identification, mode of action, structure/function and exploitation of these toxins and finally highlight the unresolved issues related to their pharmacological studies., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

The snake toxin MT7 is a potent and specific allosteric modulator of the human M1 muscarinic receptor (hM1). We previously characterized by mutagenesis experiments the functional determinants of the MT7-hM1 receptor interaction (Fruchart-Gaillard, C., Mourier, G., Marquer, C., Stura, E., Birdsall, N. J., and Servent, D. (2008) Mol. Pharmacol. 74, 1554-1563) and more recently collected evidence indicating that MT7 may bind to a dimeric form of hM1 (Marquer, C., Fruchart-Gaillard, C., Mourier, G., Grandjean, O., Girard, E., le Maire, M., Brown, S., and Servent, D. (2010) Biol. Cell 102, 409-420). To structurally characterize the MT7-hM1 complex, we adopted a strategy combining double mutant cycle experiments and molecular modeling calculations. First, thirty-three ligand-receptor proximities were identified from the analysis of sixty-one double mutant binding affinities. Several toxin residues that are more than 25 Å apart still contact the same residues on the receptor. As a consequence, attempts to satisfy all the restraints by docking the toxin onto a single receptor failed. The toxin was then positioned onto two receptors during five independent flexible docking simulations. The different possible ligand and receptor extracellular loop conformations were described by performing simulations in explicit solvent. All the docking calculations converged to the same conformation of the MT7-hM1 dimer complex, satisfying the experimental restraints and in which (i) the toxin interacts with the extracellular side of the receptor, (ii) the tips of MT7 loops II and III contact one hM1 protomer, whereas the tip of loop I binds to the other protomer, and (iii) the hM1 dimeric interface involves the transmembrane helices TM6 and TM7. These results structurally support the high affinity and selectivity of the MT7-hM1 interaction and highlight the atypical mode of interaction of this allosteric ligand on its G protein-coupled receptor target.

Amyloid peptide (Aβ) is generated by sequential cleavage of the amyloid precursor protein (APP) by β-secretase (Bace1) and γ-secretase. Aβ production increases after plasma membrane cholesterol loading through unknown mechanisms. To determine how APP-Bace1 proximity affects this phenomenon, we developed a fluorescence lifetime imaging microscopy-Förster resonance energy transfer (FLIM-FRET) technique for visualization of these molecules either by epifluorescence or at the plasma membrane only using total internal reflection fluorescence. Further, we used fluorescence correlation spectroscopy to determine the lipid rafts partition of APP-yellow fluorescent protein (YFP) and Bace1-green fluorescent protein (GFP) molecules at the plasma membrane of neurons. We show that less than 10 min after cholesterol exposure, Bace1-GFP/APP-mCherry proximity increases selectively at the membrane and APP relocalizes to raft domains, preceded by rapid endocytosis. After longer cholesterol exposures, APP and Bace1 are found in proximity intracellularly. We demonstrate that cholesterol loading does not increase Aβ production by having a direct impact on Bace1 catalytic activity but rather by altering the accessibility of Bace1 to its substrate, APP. This change in accessibility is mediated by clustering in lipid rafts, followed by rapid endocytosis.

An increasing number of results implicating cholesterol metabolism in the pathophysiology of Alzheimer's disease (AD) suggest cholesterol as a target for treatment. Research in genetics, pathology, epidemiology, biochemistry, and cell biology, as well as in animal models, suggests that cholesterol, its transporter in the brain, apolipoprotein E, amyloid precursor protein, and amyloid-beta all interact in AD pathogenesis. Surprisingly, key questions remain unanswered due to the lack of sensitive and specific methods for assessing cholesterol levels in the brain at subcellular resolution. The aims of this review are not only to discuss the various methods for measuring cholesterol and its metabolites and to catalog results obtained from AD patients but also to discuss some new data linking high plasma membrane cholesterol with modifications of the endocytic compartments. These studies are particularly relevant to AD pathology, since enlarged endosomes are believed to be the first morphological change observed in AD brains, in both sporadic cases and Down syndrome., (Copyright 2010 Elsevier B.V. All rights reserved.)

Several lines of evidence support a strong relationship between cholesterol and Alzheimer's disease pathogenesis. Membrane cholesterol is known to modulate amyloid precursor protein (APP) endocytosis and amyloid-beta (Abeta) secretion. Here we show in a human cell line model of endocytosis (HEK293 cells) that cholesterol exerts these effects in a dose-dependent and linear manner, over a wide range of concentrations (-40% to +40% variations of plasma membrane cholesterol induced by methyl-beta-cyclodextrin (MBCD) and MBCD-cholesterol complex respectively). We found that the gradual effect of cholesterol is inhibited by small interference RNA-mediated downregulation of clathrin. Modulation of clathrin-mediated APP endocytosis by cholesterol was further demonstrated using mutants of proteins involved in the formation of early endosomes (dynamin2, Eps15 and Rab5). Importantly we show that membrane proteins other than APP are not affected by cholesterol to the same extent. Indeed clathrin-dependent endocytosis of transferrin and cannabinoid1 receptors as well as internalization of surface proteins labelled with a biotin derivative (sulfo-NHS-SS-biotin) were not sensitive to variations of plasma membrane cholesterol from -40% to 40%. In conclusion clathrin-dependent APP endocytosis appears to be very sensitive to the levels of membrane cholesterol. These results suggest that cholesterol increase in AD could be responsible for the enhanced internalization of clathrin-, dynamin2-, Eps15- and Rab5-dependent endocytosis of APP and the ensuing overproduction of Abeta., (Copyright 2010 Elsevier B.V. All rights reserved.)

Background Information: The idea that GPCRs (G-protein-coupled receptors) may exist as homo- or hetero-oligomers, although still controversial, is now widely accepted. Nevertheless, the functional roles of oligomerization are still unclear and gaining greater insight into the mechanisms underlying the dynamics of GPCR assembly and, in particular, assessing the effect of ligands on this process seems important. We chose to focus our present study on the effect of MT7 (muscarinic toxin 7), a highly selective allosteric peptide ligand, on the oligomerization state of the hM1 (human M1 muscarinic acetylcholine receptor subtype)., Results: We analysed the hM1 oligomerization state in membrane preparations or in live cells and observed the effect of MT7 via four complementary techniques: native-PAGE electrophoresis analysed by both Western blotting and autoradiography on solubilized membrane preparations of CHO-M1 cells (Chinese-hamster ovary cells expressing muscarinic M1 receptors); FRET (fluorescence resonance energy transfer) experiments on cells expressing differently tagged M1 receptors using either an acceptor photobleaching approach or a novel fluorescence emission anisotropy technique; and, finally, by BRET (bioluminescence resonance energy transfer) assays. Our results reveal that MT7 seems to protect the M1 receptor from the dissociating effect of the detergent and induces an increase in the FRET and BRET signals, highlighting its ability to affect the dimeric form of the receptor., Conclusions: Our results suggest that MT7 binds to a dimeric form of hM1 receptor, favouring the stability of this receptor state at the cellular level, probably by inducing some conformational rearrangements of the pre-existing muscarinic receptor homodimers.

Background and Purpose: Venoms are a rich source of ligands for ion channels, but very little is known about their capacity to modulate G-protein coupled receptor (GPCR) activity. We developed a strategy to identify novel toxins targeting GPCRs., Experimental Approach: We studied the interactions of mamba venom fractions with alpha(1)-adrenoceptors in binding experiments with (3)H-prazosin. The active peptide (AdTx1) was sequenced by Edman degradation and mass spectrometry fragmentation. Its synthetic homologue was pharmacologically characterized by binding experiments using cloned receptors and by functional experiments on rabbit isolated prostatic smooth muscle., Key Results: AdTx1, a 65 amino-acid peptide stabilized by four disulphide bridges, belongs to the three-finger-fold peptide family. It has subnanomolar affinity (K(i)= 0.35 nM) and high specificity for the human alpha(1A)-adrenoceptor subtype. We showed high selectivity and affinity (K(d)= 0.6 nM) of radio-labelled AdTx1 in direct binding experiments and revealed a slow association constant (k(on)= 6 x 10(6).M(-1).min(-1)) with an unusually stable alpha(1A)-adrenoceptor/AdTx1 complex (t(1/2diss)= 3.6 h). AdTx1 displayed potent insurmountable antagonism of phenylephrine's actions in vitro (rabbit isolated prostatic muscle) at concentrations of 10 to 100 nM., Conclusions and Implications: AdTx1 is the most specific and selective peptide inhibitor for the alpha(1A)-adrenoceptor identified to date. It displays insurmountable antagonism, acting as a potent relaxant of smooth muscle. Its peptidic nature can be exploited to develop new tools, as a radio-labelled-AdTx1 or a fluoro-labelled-AdTx1. Identification of AdTx1 thus offers new perspectives for developing new drugs for treating benign prostatic hyperplasia.

Muscarinic MT7 toxin is a highly selective and potent antagonist of the M(1) subtype of muscarinic receptor and acts by binding to an allosteric site. To identify the molecular determinants by which MT7 toxin interacts with this receptor in its free and NMS-occupied states, the effect on toxin potency of alanine substitution was evaluated in equilibrium and kinetic binding experiments as well as in functional assays. The determination of the crystallographic structure of an MT7-derivative (MT7-diiodoTyr51) allowed the selection of candidate residues that are accessible and present on both faces of the three toxin loops. The equilibrium binding data are consistent with negative cooperativity between N-methylscopolamine (NMS) and wild-type or modified MT7 and highlight the critical role of the tip of the central loop of the toxin (Arg34, Met35 Tyr36) in its interaction with the unoccupied receptor. Examination of the potency of wild-type and modified toxins to allosterically decrease the dissociation rate of [(3)H]NMS allowed the identification of the MT7 residues involved in its interaction with the NMS-occupied receptor. In contrast to the results with the unoccupied receptor, the most important residue for this interaction was Tyr36 in loop II, assisted by Trp10 in loop I and Arg52 in loop III. The critical role of the tips of the MT7 loops was also confirmed in functional experiments. The high specificity of the MT7-M(1) receptor interaction exploits several MT7-specific residues and reveals a different mode of interaction of the toxin with the free and NMS-occupied states of the receptor.

Monoiodinated, Met35-oxidized muscarinic toxin 7 (MT7ox) was synthesized, and its affinity constants for free or N-methyl scopolamine (NMS)-occupied hM1 receptor were measured directly by equilibrium and kinetic binding experiments. Identical values were obtained with the two types of assay methods, 14 pM and 0.9 nM in free or NMS-liganded receptor states, respectively, highlighting a strong negative cooperativity between this allosteric toxin and NMS. Identical results were obtained with indirect binding experiments with [3H]NMS using the ternary complex model, clearly demonstrating the reciprocal nature of this cooperativity. Furthermore, the effects of various orthosteric and allosteric agents on the dissociation kinetic of 125I-MT7ox were measured and show that, except for the MT1 toxin, all of the ligands studied [NMS, atropine, gallamine, brucine, tacrine, staurosporine, and (9S,10S,12R)-2,3,9,10,11-hexahydro-10-hydroxy-9-methyl-1-oxo-9,12-epoxy-1H-diindolo[1,2,3-fg:3',2',1'-kl]pyrrolo[3,4-i][1,6]benzodiazocine-10-carboxylic acid hexyl ester (KT5720)] interact allosterically with muscarinic toxin 7. Equilibrium binding experiments with 125I-MT7ox and [3H]NMS were conducted to reveal the effects of these ligands on the free receptor, and affinity constants (pKx values) were calculated using the allosteric ternary complex model. Our results suggest that MT7 toxin interacts with hM1 receptor at a specific allosteric site, which may partially overlap those identified previously for "classic" or "atypical" allosteric agents and highlight the potential of this new allosteric tracer in studying allosterism at muscarinic receptors.

Three-finger-fold toxins, isolated from various snake venoms, are recognized by high affinity and various specificities by different nicotinic and muscarinic acetylcholine receptors (nAChRs and mAChRs, respectively) present in peripheral, as well as central, nervous systems (Karlsson et al., 2000; Servent and Ménez, 2001; Nirthanan and Gwee, 2004). The goal of our studies is (1) to identify, at the molecular level, the functional determinants involved in the various interaction profiles of nicotinic or muscarinic toxins on their respective receptors subtypes, (2) to model some of these toxin-receptor complexes using distance constraints obtained from cycle-mutant experiments, and (3) to understand how a unique scaffold (the three-finger fold) is able to support these different functional profiles and how molecular determinants have been selected during the evolution process to create these different specific properties. Finally, these structure/function analyses should be exploited to engineer non-natural peptides with new binding and functional properties useful as pharmacological tools or therapeutic agents.