109 results on '"M. Gamage"'
Search Results
2. Application of a bespoke monoclonal antibody panel to characterize immune cell populations in cave nectar bats
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Shiwei Chen, Wan Rong Sia, Leon J.W. Tang, Akshamal M. Gamage, Wharton O.Y. Chan, Feng Zhu, Wanni Chia, Madeline S.S. Kwek, Pui San Kong, Beng Lee Lim, Randy Foo, Wei Lun Ng, Adrian H.J. Tan, Shan He, Abigail Y.T. Loh, Dolyce H.W. Low, Gavin J.D. Smith, Lewis Z. Hong, and Lin-Fa Wang
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Biology (General) ,QH301-705.5 - Published
- 2024
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3. Validation and analysis of the Polair3D v1.11 chemical transport model over Quebec
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S. Yamanouchi, S. M. Gamage, S. Torbatian, J. Zalzal, L. Minet, A. Smargiassi, Y. Liu, L. Liu, F. Azargoshasbi, J. Kim, Y. Kim, D. Yazgi, and M. Hatzopoulou
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Geology ,QE1-996.5 - Abstract
Air pollution is a major health hazard, and while air quality overall has been improving in industrialized nations, pollution is still a major economic and public health issue, with some species, such as ozone (O3), still exceeding the standards set by governing agencies. Chemical transport models (CTMs) are valuable tools that aid in our understanding of the risks of air pollution both at local and regional scales. In this study, the Polair3D v1.11 CTM of the Polyphemus air quality modeling platform was set up over Quebec, Canada, to assess the model's capability in predicting key air pollutant species over the region, at seasonal temporal scales and at regional spatial scales. The simulation by the model included three nested domains, at horizontal resolutions of 9 km by 9 km and 3 km by 3 km, as well as two 1 km by 1 km domains covering the cities of Montréal and Québec. We find that the model captures the spatial variability and seasonal effects and, to a lesser extent, the hour-by-hour or day-to-day temporal variability for a fixed location. The model at both the 3 km and the 1 km resolution struggled to capture high-frequency temporal variability and showed large variabilities in correlation and bias from site to site. When comparing the biases and correlation at a site-wide scale, the 3 km domain showed slightly higher correlation for carbon monoxide (CO), nitrogen dioxide (NO2), and nitric oxide (NO), while ozone (O3), sulfur dioxide (SO2), and PM2.5 showed slight increases in correlation at the 1 km domain. The performance of the Polair3D model was in line with other models over Canada and comparable to Polair3D's performance over Europe.
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- 2024
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4. Longitudinal single cell atlas identifies complex temporal relationship between type I interferon response and COVID-19 severity
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Quy Xiao Xuan Lin, Deepa Rajagopalan, Akshamal M. Gamage, Le Min Tan, Prasanna Nori Venkatesh, Wharton O. Y. Chan, Dilip Kumar, Ragini Agrawal, Yao Chen, Siew-Wai Fong, Amit Singh, Louisa J. Sun, Seow-Yen Tan, Louis Yi Ann Chai, Jyoti Somani, Bernett Lee, Laurent Renia, Lisa F P Ng, Kollengode Ramanathan, Lin-Fa Wang, Barnaby Young, David Lye, Amit Singhal, and Shyam Prabhakar
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Science - Abstract
Abstract Due to the paucity of longitudinal molecular studies of COVID-19, particularly those covering the early stages of infection (Days 1-8 symptom onset), our understanding of host response over the disease course is limited. We perform longitudinal single cell RNA-seq on 286 blood samples from 108 age- and sex-matched COVID-19 patients, including 73 with early samples. We examine discrete cell subtypes and continuous cell states longitudinally, and we identify upregulation of type I IFN-stimulated genes (ISGs) as the predominant early signature of subsequent worsening of symptoms, which we validate in an independent cohort and corroborate by plasma markers. However, ISG expression is dynamic in progressors, spiking early and then rapidly receding to the level of severity-matched non-progressors. In contrast, cross-sectional analysis shows that ISG expression is deficient and IFN suppressors such as SOCS3 are upregulated in severe and critical COVID-19. We validate the latter in four independent cohorts, and SOCS3 inhibition reduces SARS-CoV-2 replication in vitro. In summary, we identify complexity in type I IFN response to COVID-19, as well as a potential avenue for host-directed therapy.
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- 2024
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5. Vulnerability Scanning Tool for Software-Define Network Controller.
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G. G. I. V. M. Gamage, B. S. Sithmini, N. W. Harshani Jayawardhana, R. H. M. I. D. Rajakaruna, and Uditha Dharmakeerthi
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- 2023
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6. Generation of self-replicating airway organoids from the cave nectar bat Eonycteris spelaea as a model system for studying host–pathogen interactions in the bat airway epithelium
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Louisa L.Y. Chan, Akshamal M. Gamage, Chee Wah Tan, Kai Sen Tan, Jing Liu, Douglas Jie Wen Tay, Randy Jee Hiang Foo, Laurent Rénia, De Yun Wang, and Lin-Fa Wang
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Bat ,Chiroptera ,Eonycteris spelaea ,airway organoids ,airway epithelial cells ,Infectious and parasitic diseases ,RC109-216 ,Microbiology ,QR1-502 - Abstract
Bats are reservoir hosts for various zoonotic viruses with pandemdic potential in humans and livestock. In vitro systems for studying bat host–pathogen interactions are of significant interest. Here, we establish protocols to generate bat airway organoids (AOs) and airway epithelial cells differentiated at the air–liquid interface (ALI-AECs) from tracheal tissues of the cave-nectar bat Eonycteris spelaea. In particular, we describe steps which enable laboratories that do not have access to live bats to perform extended experimental work upon procuring an initial batch of bat primary airway tissue. Complete mucociliary differentiation required treatment with IL-13. E. spelaea ALI-AECs supported productive infection with PRV3M, an orthoreovirus for which Pteropodid bats are considered the reservoir species. However, these ALI-AECs did not support SARS-CoV-2 infection, despite E. spelaea ACE2 receptor being capable of mediating SARS-CoV-2 spike pseudovirus entry. This work provides critical model systems for assessing bat species-specific virus susceptibility and the reservoir likelihood for emerging infectious agents.
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- 2023
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7. Pteropine orthoreoviruses use cell surface heparan sulphate as an attachment receptor
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Chee Wah Tan, Akshamal M. Gamage, Wee Chee Yap, Leon Jia Wei Tang, Yuan Sun, Xing-Lou Yang, Alyssa Pyke, Kaw Bing Chua, and Lin-Fa Wang
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Pteropine orthoreovirus ,heparan sulphate ,attachment receptor ,Melaka virus ,glycosaminoglycans ,Infectious and parasitic diseases ,RC109-216 ,Microbiology ,QR1-502 - Abstract
Pteropine orthoreoviruses (PRVs) are an emerging group of fusogenic, bat-borne viruses from the Orthoreovirus genus. Since the isolation of PRV from a patient with acute respiratory tract infections in 2006, the zoonotic potential of PRV has been further highlighted following subsequent isolation of PRV species from patients in Malaysia, Hong Kong and Indonesia. However, the entry mechanism of PRV is currently unknown. In this study, we investigated the role of previously identified mammalian orthoreovirus (MRV) receptors, sialic acid and junctional adhesion molecule-1 for PRV infection. However, none of these receptors played a significant role in PRV infection, suggesting PRV uses a distinct entry receptor from MRV. Given its broad tissue tropism, we hypothesized that PRV may use a receptor that is widely expressed in all cell types, heparan sulphate (HS). Enzymatic removal of cell surface HS by heparinase treatment and genetic ablation of HS biosynthesis genes, SLC35B2, exostosin-1, N-deacetylase/N-sulfotransferase I and beta-1,3-glucuronyltransferase 3, significantly reduced infection with multiple genetically distinct PRV species. Replication kinetic of PRV3M in HS knockout cells revealed that HS plays a crucial role in the early phase of PRV infection. Mechanistic studies demonstrated that HS is an essential host-factor for PRV attachment and internalization into cells. To our knowledge, this is the first report on the use of HS as an attachment receptor by PRVs.
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- 2023
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8. Betacoronaviruses SARS-CoV-2 and HCoV-OC43 infections in IGROV-1 cell line require aryl hydrocarbon receptor
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Meisam Yousefi, Wai Suet Lee, Wharton O. Y. Chan, Wei He, Marcus G. Mah, Cythia Lingli Yong, Joshua M. Deerain, Lijin Wang, Camille Arcinas, Biaoguo Yan, Dewei Tan, Wan Rong Sia, Akshamal M. Gamage, Jinxuan Yang, Alan Chen-Yu Hsu, Shang Li, Martin Linster, Xinglou Yang, Sujoy Ghosh, Danielle E. Anderson, Gavin J. D. Smith, Chee Wah Tan, Lin-Fa Wang, and Yaw Shin Ooi
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IGROV-1 ,COVID-19 ,betacoronavirus ,SARS-CoV-2 ,HCoV-OC43 ,Genome-scale CRISPR screening ,Infectious and parasitic diseases ,RC109-216 ,Microbiology ,QR1-502 - Abstract
The emergence of novel betacoronaviruses has posed significant financial and human health burdens, necessitating the development of appropriate tools to combat future outbreaks. In this study, we have characterized a human cell line, IGROV-1, as a robust tool to detect, propagate, and titrate betacoronaviruses SARS-CoV-2 and HCoV-OC43. IGROV-1 cells can be used for serological assays, antiviral drug testing, and isolating SARS-CoV-2 variants from patient samples. Using time-course transcriptomics, we confirmed that IGROV-1 cells exhibit a robust innate immune response upon SARS-CoV-2 infection, recapitulating the response previously observed in primary human nasal epithelial cells. We performed genome-wide CRISPR knockout genetic screens in IGROV-1 cells and identified Aryl hydrocarbon receptor (AHR) as a critical host dependency factor for both SARS-CoV-2 and HCoV-OC43. Using DiMNF, a small molecule inhibitor of AHR, we observed that the drug selectively inhibits HCoV-OC43 infection but not SARS-CoV-2. Transcriptomic analysis in primary normal human bronchial epithelial cells revealed that DiMNF blocks HCoV-OC43 infection via basal activation of innate immune responses. Our findings highlight the potential of IGROV-1 cells as a valuable diagnostic and research tool to combat betacoronavirus diseases.
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- 2023
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9. Human Nasal Epithelial Cells Sustain Persistent SARS-CoV-2 Infection In Vitro, despite Eliciting a Prolonged Antiviral Response
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Akshamal M. Gamage, Kai Sen Tan, Wharton O. Y. Chan, Zhe Zhang Ryan Lew, Jing Liu, Chee Wah Tan, Deepa Rajagopalan, Quy Xiao Xuan Lin, Le Min Tan, Prasanna Nori Venkatesh, Yew Kwang Ong, Mark Thong, Raymond Tzer Pin Lin, Shyam Prabhakar, De Yun Wang, and Lin-Fa Wang
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COVID-19 ,nasal epithelial cells ,SARS-CoV-2 ,single-cell sequencing ,viral persistence ,Microbiology ,QR1-502 - Abstract
ABSTRACT The dynamics of SARS-CoV-2 infection in COVID-19 patients are highly variable, with a subset of patients demonstrating prolonged virus shedding, which poses a significant challenge for disease management and transmission control. In this study, the long-term dynamics of SARS-CoV-2 infection were investigated using a human well-differentiated nasal epithelial cell (NEC) model of infection. NECs were observed to release SARS-CoV-2 virus onto the apical surface for up to 28 days postinfection (dpi), further corroborated by viral antigen staining. Single-cell transcriptome sequencing (sc-seq) was utilized to explore the host response from infected NECs after short-term (3-dpi) and long-term (28-dpi) infection. We identified a unique population of cells harboring high viral loads present at both 3 and 28 dpi, characterized by expression of cell stress-related genes DDIT3 and ATF3 and enriched for genes involved in tumor necrosis factor alpha (TNF-α) signaling and apoptosis. Remarkably, this sc-seq analysis revealed an antiviral gene signature within all NEC cell types even at 28 dpi. We demonstrate increased replication of basal cells, absence of widespread cell death within the epithelial monolayer, and the ability of SARS-CoV-2 to replicate despite a continuous interferon response as factors likely contributing to SARS-CoV-2 persistence. This study provides a model system for development of therapeutics aimed at improving viral clearance in immunocompromised patients and implies a crucial role for immune cells in mediating viral clearance from infected epithelia. IMPORTANCE Increasing medical attention has been drawn to the persistence of symptoms (long-COVID syndrome) or live virus shedding from subsets of COVID-19 patients weeks to months after the initial onset of symptoms. In vitro approaches to model viral or symptom persistence are needed to fully dissect the complex and likely varied mechanisms underlying these clinical observations. We show that in vitro differentiated human NECs are persistently infected with SARS-CoV-2 for up to 28 dpi. This viral replication occurred despite the presence of an antiviral gene signature across all NEC cell types even at 28 dpi. This indicates that epithelial cell intrinsic antiviral responses are insufficient for the clearance of SARS-CoV-2, implying an essential role for tissue-resident and infiltrating immune cells for eventual viral clearance from infected airway tissue in COVID-19 patients.
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- 2022
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10. The Potential Impact of COVID-19 Pandemic on the Antenatal Care as Perceived by Non-COVID-19 Pregnant Women: Women’s Experience Research Brief
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Malitha Patabendige MBBS, MD (O&G), Madhawa M Gamage MBBS, and Asanka Jayawardane MBBS, MD, M.Phil, MRCOG
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Medicine (General) ,R5-920 - Abstract
We aimed to study the impact of Coronavirus disease 2019 (COVID-19) pandemic on the basic antenatal care received during the. A facility-based descriptive cross-sectional study was conducted and 62 pregnant women were interviewed. A total of 80.6% of mothers were satisfied with the quality of antenatal care they received, ≥ 7 of 10 on visual analogue scales (VAS). The majority of women were not confident to deliver their baby and 58.1% of women showed ≤ 5 of 10 on VAS. Midwife (90.3%) was the commonest source of information. Internet (1.6%) was a poor source. The impact of the COVID-19 pandemic on the quality of antenatal care was significant, and the findings are useful for the policymakers to plan necessary actions.
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- 2021
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11. Infection of human Nasal Epithelial Cells with SARS-CoV-2 and a 382-nt deletion isolate lacking ORF8 reveals similar viral kinetics and host transcriptional profiles.
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Akshamal M Gamage, Kai Sen Tan, Wharton O Y Chan, Jing Liu, Chee Wah Tan, Yew Kwang Ong, Mark Thong, Anand K Andiappan, Danielle E Anderson, De Yun Wang, and Lin-Fa Wang
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Immunologic diseases. Allergy ,RC581-607 ,Biology (General) ,QH301-705.5 - Abstract
The novel coronavirus SARS-CoV-2 is the causative agent of Coronavirus Disease 2019 (COVID-19), a global healthcare and economic catastrophe. Understanding of the host immune response to SARS-CoV-2 is still in its infancy. A 382-nt deletion strain lacking ORF8 (Δ382 herein) was isolated in Singapore in March 2020. Infection with Δ382 was associated with less severe disease in patients, compared to infection with wild-type SARS-CoV-2. Here, we established Nasal Epithelial cells (NECs) differentiated from healthy nasal-tissue derived stem cells as a suitable model for the ex-vivo study of SARS-CoV-2 mediated pathogenesis. Infection of NECs with either SARS-CoV-2 or Δ382 resulted in virus particles released exclusively from the apical side, with similar replication kinetics. Screening of a panel of 49 cytokines for basolateral secretion from infected NECs identified CXCL10 as the only cytokine significantly induced upon infection, at comparable levels in both wild-type and Δ382 infected cells. Transcriptome analysis revealed the temporal up-regulation of distinct gene subsets during infection, with anti-viral signaling pathways only detected at late time-points (72 hours post-infection, hpi). This immune response to SARS-CoV-2 was significantly attenuated when compared to infection with an influenza strain, H3N2, which elicited an inflammatory response within 8 hpi, and a greater magnitude of anti-viral gene up-regulation at late time-points. Remarkably, Δ382 induced a host transcriptional response nearly identical to that of wild-type SARS-CoV-2 at every post-infection time-point examined. In accordance with previous results, Δ382 infected cells showed an absence of transcripts mapping to ORF8, and conserved expression of other SARS-CoV-2 genes. Our findings shed light on the airway epithelial response to SARS-CoV-2 infection, and demonstrate a non-essential role for ORF8 in modulating host gene expression and cytokine production from infected cells.
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- 2020
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12. Evaluation of the Potential of Fungal Acid Proteases of Aspergillus flavus, Aspergillus niger and Penicillium sp. to Produce Shrimp-Waste Protein Hydrolysates with Degraded Antigenic Proteins
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M. Gamage, N. Liyanage, I. Pathirana, S. Ediriweera, and L. Prabodha
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The waste produced by the shrimp industry can be a great source for the recovery of important bioactive compounds with potential applications in food industry. The present study aimed to characterize extracted proteases of Aspergillus flavus, Aspergillus niger and Penicillium sp. to be utilized as potential sources to produce shrimp waste protein hydrolysates with degraded antigenic proteins. The extracellular fungal acid protease enzymes were extracted under solid substrate fermentation and partially characterized the enzyme activities, concerning the reaction temperature and pH of the reaction medium. Then, the capabilities of extracted fungal protease enzymes to reduce the potential allergens of shrimp waste protein hydrolysates were examined by SDS-PAGE. After incubation of all three fungal species at 37°C and pH 3.0 for 5 days, the highest protease yield, 527.40 μg/mL was achieved from A. flavus. The optimum temperature for A. flavus for the highest protease activity was 45°C, while for other two microorganisms the optimum temperature was 50°C. The optimum pH values for all three proteases were pH 3. According to the SDS-PAGE protein hydrolyzing patterns, the crude acid protease extracted from A. flavus was the best protease to degrade the potential antigenic proteins over the other two acid proteases extracted from A.niger and Penicillium sp., while all three enzymes had shown the potential to reduce the allergenic capacity of shrimp waste proteins through enzymatic hydrolysis.
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- 2022
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13. 3D-Printed Metal-Organic Frameworks (MOFs) for Sensors
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Vithyasaahar Sethumadhavan, Preethichandra D. M. Gamage, and Prashant Sonar
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- 2023
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14. A Survey on Blockchain Technology Concepts, Applications, and Issues.
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H. T. M. Gamage, H. D. Weerasinghe, and N. G. J. Dias
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- 2020
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15. Poster Presentations
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N. Sutamam, Florent Ginhoux, Barnaby Edward Young, Akshamal M. Gamage, Karen Donceras Nadua, Pavanish Kumar, Chee Fu Yung, Natalie Woon Hui Tan, Amanda Jin Mei Lim, D. Guo, Cheng Tung Chong, K. S. Yeo, Su Li Poh, Jiahui Li, Jing Yao Leong, Randy Foo, Katherine Nay Yaung, Xiao Qian Ng, Joo Guan Yeo, David C. Lye, Camillus Chua, Sharifah Nur Hazirah, Martin Qui, Jerry Kok Yen Chan, Martin Wasser, Lin-Fa Wang, Thaschawee Arkachaisri, Kai Qian Kam, Koh Cheng Thoon, Danielle E. Anderson, Salvatore Albani, L. Ramakrishna, and Shi Huan Tay
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biology ,business.industry ,FOXP3 ,Human leukocyte antigen ,CXCR3 ,Immune system ,Rheumatology ,TIGIT ,Immunology ,biology.protein ,Medicine ,IL-2 receptor ,Antibody ,business ,CD8 - Abstract
Background/Purpose: The global coronavirus disease 2019 (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) resulted in significant mortality, social disorder and economic hardships. We set out to understand why certain individuals could resolve the disease successfully without serious complications by immune profiling of PBMCs from convalescent COVID-19 patients (n = 14) with mild disease trajectory. Methods: We designed 7 peptides targeting the receptor binding region (RBD) of the spike protein of SARS-CoV-2, that encompass broad HLA class I / II alleles, with the aid of the Immune Epitope Database and Analysis Resource (IEDB) website. The RBD site was chosen as it was shown to be protective when neutralising antibodies against this region could negate binding of viral spike protein to host cell ACE-2 receptor. Convalescent COVID-19 patients enrolled in this study were screened and selected for positive antibody titre against the RBD region. PBMCs from convalescent COVID-19 patients were stimulated with/without the peptides for 72hrs and immune profiled (n = 70 markers across two panels) with the high dimensional single cell mass cytometry platform (CyToF). Results: Convalescent COVID-19 patients elicited a robust recall memory T follicular helper response (CD3 + CD4 + CD45RO + CXCR5 + Tigit + ;∗∗∗∗ p < 0.0001) demonstrating peptide efficacy. Unsupervised clustering (FlowSOM) of the CD4 T cell immune landscape reaffirmed increase in memory T follicular subsets and additionally CD4 + CD45RO + CXCR5 -subsets. Further gating of antigen specific memory cells (CD45RO + CD69 + ) revealed an increase in Tbet + CXCR3 + T effectors in both CD4 and CD8 compartments. Strikingly we detected a parallel increase in CD4 + Treg (CD25 + FoxP3 + ) CXCR3 + Tbet + CD45RO + CD152 + Tigit + expression. Conclusions: COVID-19 patients that successfully resolve the viral infection not only mount a robust T effector and follicular response but also in tandem a similar T regulatory profile.
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- 2021
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16. Generation of self-replicating airway organoids from the cave nectar bat
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Louisa L Y, Chan, Akshamal M, Gamage, Chee Wah, Tan, Kai Sen, Tan, Jing, Liu, Douglas Jie Wen, Tay, Randy Jee Hiang, Foo, Laurent, Rénia, De Yun, Wang, and Lin-Fa, Wang
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Bats are reservoir hosts for various zoonotic viruses with pandemdic potential in humans and livestock.
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- 2022
17. Mechanistic Pathways for N2O Elimination from trans-R3Sn-O-N═N-O-SnR3 and for Reversible Binding of CO2 to R3Sn-O-SnR3 (R = Ph, Cy)
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Manuel Temprado, Jack V. Davis, Carl D. Hoff, Mohan M. Gamage, Oswaldo Guio, and Burjor Captain
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Atmospheric temperature range ,Toluene ,Medicinal chemistry ,Intermediate product ,Product distribution ,Inorganic Chemistry ,Metal ,chemistry.chemical_compound ,chemistry ,Hyponitrite ,Yield (chemistry) ,visual_art ,visual_art.visual_art_medium ,Physical and Theoretical Chemistry ,Benzene - Abstract
The rate and mechanism of the elimination of N2O from trans-R3Sn-O-N═N-O-SnR3 (R = Ph (1Ph) and R = Cy (1Cy)) to form R3Sn-O-SnR3 (R = Ph (2Ph) and R = Cy (2Cy)) have been studied using both NMR and IR techniques to monitor the reactions in the temperature range of 39-79 °C in C6D6. Activation parameters for this reaction are ΔH⧧ = 15.8 ± 2.0 kcal·mol-1 and ΔS⧧ = -28.5 ± 5 cal·mol-1·K-1 for 1Ph and ΔH⧧ = 22.7 ± 2.5 kcal·mol-1 and ΔS⧧ = -12.4 ± 6 cal·mol-1·K-1 for 1Cy. Addition of O2, CO2, N2O, or PPh3 to sealed tube NMR experiments did not alter in a detectable way the rate or product distribution of the reactions. Computational DFT studies of elimination of hyponitrite from trans-Me3Sn-O-N═N-O-SnMe3 (1Me) yield a mechanism involving initial migration of the R3Sn group from O to N passing through a marginally stable intermediate product and subsequent N2O elimination. Reactions of 1Ph with protic acids HX are rapid and lead to formation of R3SnX and trans-H2N2O2. Reaction of 1Ph with the metal radical •Cr(CO)3C5Me5 at low concentrations results in rapid evolution of N2O. At higher •Cr(CO)3C5Me5 concentrations, evolution of CO2 rather than N2O is observed. Addition of 1 atm or less CO2 to benzene or toluene solutions of 2Ph and 2Cy resulted in very rapid reaction to form the corresponding carbonates R3Sn-O-C(═O)-O-SnR3 (R = Ph (3Ph) and R = Cy (3Cy)) at room temperature. Evacuation results in fast loss of bound CO2 and regeneration of 2Ph and 2Cy. Variable temperature data for formation of 3Cy yield ΔHo = -8.7 ± 0.6 kcal·mol-1, ΔSo = -17.1 ± 2.0 cal·mol-1·K-1, and ΔGo298K = -3.6 ± 1.2 kcal·mol-1. DFT studies were performed and provide additional insight into the energetics and mechanisms for the reactions.
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- 2021
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18. An Evaluation of Sri Lankan English Textbooks : With a Focus on Interethnic Communiative Competence
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Cheongmin Yook, Oshadi V. M. Gamage, and MA Student
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Pedagogy ,Sociology ,Competence (human resources) - Published
- 2020
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19. Psychological impact of the COVID‐19 pandemic among pregnant women in Sri Lanka
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Madhawa M. Gamage, Malika Weerasinghe, M. Patabendige, and Asanka Jayawardane
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Pregnancy ,medicine.medical_specialty ,Coronavirus disease 2019 (COVID-19) ,business.industry ,Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) ,Obstetrics and Gynecology ,General Medicine ,medicine.disease ,Hospital Anxiety and Depression Scale ,Pandemic ,medicine ,Anxiety ,medicine.symptom ,Sri lanka ,Psychiatry ,business ,Depression (differential diagnoses) - Published
- 2020
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20. Role of Animals in the COVID-19 Outbreak
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Lin-Fa Wang, Akshamal M Gamage, and Wharton Chan
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- 2022
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21. Human Nasal Epithelial Cells (hNECs) Generated by Air-Liquid Interface (ALI) Culture as a Model System for Studying the Pathogenesis of SARS-CoV-2
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Kai Sen Tan, Akshamal M. Gamage, and Jing Liu
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- 2022
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22. The establishment of COPD organoids to study host-pathogen interaction reveals enhanced viral fitness of SARS-CoV-2 in bronchi
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Louisa L. Y. Chan, Danielle E. Anderson, Hong Sheng Cheng, Fransiskus Xaverius Ivan, Si Chen, Adrian E. Z. Kang, Randy Foo, Akshamal M. Gamage, Pei Yee Tiew, Mariko Siyue Koh, Ken Cheah Hooi Lee, Kristy Nichol, Prabuddha S. Pathinayake, Yik Lung Chan, Tsin Wen Yeo, Brian G. Oliver, Peter A. B. Wark, Linbo Liu, Nguan Soon Tan, Lin-Fa Wang, Sanjay H. Chotirmall, Lee Kong Chian School of Medicine (LKCMedicine), School of Biological Sciences, School of Chemical and Biomedical Engineering, and School of Electrical and Electronic Engineering
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Organoids ,Pulmonary Disease, Chronic Obstructive ,Multidisciplinary ,SARS-CoV-2 ,Host-Pathogen Interactions ,Humans ,General Physics and Astronomy ,COVID-19 ,Medicine [Science] ,Bronchi ,General Chemistry ,General Biochemistry, Genetics and Molecular Biology - Abstract
Chronic obstructive pulmonary disease (COPD) is characterised by airflow limitation and infective exacerbations, however, in-vitro model systems for the study of host-pathogen interaction at the individual level are lacking. Here, we describe the establishment of nasopharyngeal and bronchial organoids from healthy individuals and COPD that recapitulate disease at the individual level. In contrast to healthy organoids, goblet cell hyperplasia and reduced ciliary beat frequency were observed in COPD organoids, hallmark features of the disease. Single-cell transcriptomics uncovered evidence for altered cellular differentiation trajectories in COPD organoids. SARS-CoV-2 infection of COPD organoids revealed more productive replication in bronchi, the key site of infection in severe COVID-19. Viral and bacterial exposure of organoids induced greater pro-inflammatory responses in COPD organoids. In summary, we present an organoid model that recapitulates the in vivo physiological lung microenvironment at the individual level and is amenable to the study of host-pathogen interaction and emerging infectious disease. Ministry of Health (MOH) National Medical Research Council (NMRC) National Research Foundation (NRF) Published version This research was supported by the National Research Foundation Singapore under its COVID-19 Research Fund administered by the Singapore Ministry of Health’s National Medical Research Council (MOH000409) (to S.H.C) and National Medical Research Council COVID19RF2-0006 (to L-F.W and D.E.A.) and by the Singapore Ministry of Health’s National Medical Research Council under its Clinician Scientist Award (CSA) (MOH-000710) (S.H.C).
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- 2022
23. Project Zone : An Advanced Undergraduate Project Management System For Software Development
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T. N. E. Amarasekara, H. G. P. Isurindi, E. H. D. T. D. Navanjana, O. M. Gamage, Uthpala Samarakoon, and Archchana Kugathasan
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- 2021
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24. Decoding bat immunity: the need for a coordinated research approach
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Wharton O. Y. Chan, Akshamal M. Gamage, Michael Hiller, Lin-Fa Wang, and Emma C. Teeling
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0301 basic medicine ,History ,2019-20 coronavirus outbreak ,animal structures ,Coronavirus disease 2019 (COVID-19) ,Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) ,Viral infection ,Education ,Cell Line ,03 medical and health sciences ,0302 clinical medicine ,Immunity ,Research community ,Chiroptera ,Pandemic ,Animals ,Environmental planning ,Genome ,Comment ,Viral host response ,Computer Science Applications ,030104 developmental biology ,Geography ,Immune System ,030215 immunology - Abstract
Understanding antiviral immune responses in bats, which are reservoirs for many emerging viruses, could aid the response to future epidemics. Here, we discuss five key areas in which greater consensus among the bat research community is necessary to drive breakthroughs in the field., The COVID-19 pandemic has stressed the importance of understanding species such as bats that can serve as reservoirs for emerging viral threats. Here, Wang and colleagues call for greater consensus among the bat immunology community in five key areas.
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- 2021
25. SARS-CoV-2 D614G-infected airway organoids reveal enhanced viral fitness in COPD bronchi
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Akshamal M. Gamage, Tsin Wen Yeo, Kristy Nichol, Louisa Lok Yung Chan, Brian G. Oliver, Adrian Eng Zheng Kang, Randy Foo, Prabuddha S. Pathinayake, Ken Cheah Hooi Lee, Peter A. B. Wark, Lin-Fa Wang, Sanjay H. Chotirmall, Danielle E. Anderson, Pei Yee Tiew, and Mariko Siyue Koh
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COPD ,business.industry ,Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) ,Immunology ,Organoid ,Viral fitness ,Medicine ,Airway ,business ,medicine.disease - Published
- 2021
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26. Mixed-Metal Cluster Complexes from the Reactions of M3(CO)12 (M = Fe, Ru, Os) with the Unsaturated Complex Pt(IPr)(SnBut3)(H)
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Mohan M. Gamage, Burjor Captain, Vincent Zollo, and Sedigheh Etezadi
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Mixed metal ,Chemistry ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Biochemistry ,Medicinal chemistry ,0104 chemical sciences ,Catalysis ,Trigonal bipyramidal molecular geometry ,Yield (chemistry) ,Cluster (physics) ,General Materials Science ,0210 nano-technology ,Platinum ,Bimetallic strip - Abstract
The reaction of Ru3(CO)12 with Pt(IPr)(SnBut3)(H) at 68 °C yielded the trigonal bipyramidal cluster Ru3Pt2(IPr)2(CO)12, 1, in 32% yield. The reaction of Os3(CO)12 with Pt(IPr)(SnBut3)(H) at 68 °C furnished the triosmium–monoplatinum cluster complex Os3Pt(IPr)(CO)12, 2, in 51% yield and the triosmium–diplatinum cluster complex Os3Pt2(IPr)2(CO)12, 3, in 19% yield. The reaction of Fe3(CO)12 with Pt(IPr)(SnBut3)(H) at room temperature resulted in cluster fragmentation to afford the diiron–monoplatinum cluster complex Fe2Pt(IPr)(CO)9, 4, in 44% yield. All four compounds were structurally characterized by single-crystal X-ray diffraction analyses.
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- 2019
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27. Mechanistic Pathways for N
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Jack V, Davis, Mohan M, Gamage, Oswaldo, Guio, Burjor, Captain, Manuel, Temprado, and Carl D, Hoff
- Abstract
The rate and mechanism of the elimination of N
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- 2021
28. Differences in obstetrical care and outcomes associated with the proportion of the obstetrician's shift completed
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Lynn M. Yee, Paula McGee, Jennifer L. Bailit, Ronald J. Wapner, Michael W. Varner, John M. Thorp, Steve N. Caritis, Mona Prasad, Alan T.N. Tita, George R. Saade, Yoram Sorokin, Dwight J. Rouse, Sean C. Blackwell, Jorge E. Tolosa, G. Mallett, W. Grobman, M. Ramos-Brinson, A. Roy, L. Stein, P. Campbell, C. Collins, N. Jackson, M. Dinsmoor, J. Senka, K. Paychek, A. Peaceman, M. Talucci, M. Zylfijaj, Z. Reid, R. Leed, J. Benson, S. Forester, C. Kitto, S. Davis, M. Falk, C. Perez, K. Hill, A. Sowles, J. Postma, S. Alexander, G. Andersen, V. Scott, V. Morby, K. Jolley, J. Miller, B. Berg, K. Dorman, J. Mitchell, E. Kaluta, K. Clark, K. Spicer, S. Timlin, K. Wilson, L. Moseley, K. Leveno, M. Santillan, J. Price, K. Buentipo, V. Bludau, T. Thomas, L. Fay, C. Melton, J. Kingsbery, R. Benezue, H. Simhan, M. Bickus, D. Fischer, T. Kamon, D. DeAngelis, B. Mercer, C. Milluzzi, W. Dalton, T. Dotson, P. McDonald, C. Brezine, A. McGrail, C. Latimer, L. Guzzo, F. Johnson, L. Gerwig, S. Fyffe, D. Loux, S. Frantz, D. Cline, S. Wylie, J. Iams, M. Wallace, A. Northen, J. Grant, C. Colquitt, D. Rouse, W. Andrews, J. Moss, A. Salazar, A. Acosta, G. Hankins, N. Hauff, L. Palmer, P. Lockhart, D. Driscoll, L. Wynn, C. Sudz, D. Dengate, C. Girard, S. Field, P. Breault, F. Smith, N. Annunziata, D. Allard, J. Silva, M. Gamage, J. Hunt, J. Tillinghast, N. Corcoran, M. Jimenez, F. Ortiz, P. Givens, B. Rech, C. Moran, M. Hutchinson, Z. Spears, C. Carreno, B. Heaps, G. Zamora, J. Seguin, M. Rincon, J. Snyder, C. Farrar, E. Lairson, C. Bonino, W. Smith, K. Beach, S. Van Dyke, S. Butcher, E. Thom, M. Rice, Y. Zhao, V. Momirova, R. Palugod, B. Reamer, M. Larsen, C. Spong, S. Tolivaisa, and J.P. VanDorsten
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Episiotomy ,Adult ,medicine.medical_specialty ,medicine.medical_treatment ,Psychological intervention ,Personnel Staffing and Scheduling ,Perineum ,Lacerations ,Article ,03 medical and health sciences ,Young Adult ,0302 clinical medicine ,Obstetrics and gynaecology ,Pregnancy ,Intensive Care Units, Neonatal ,Physicians ,Medicine ,Humans ,030212 general & internal medicine ,Quality of Health Care ,030219 obstetrics & reproductive medicine ,business.industry ,Vaginal delivery ,Cesarean Section ,Obstetrics and Gynecology ,Workload ,Delivery mode ,Obstetric Labor Complications ,Obstetrics ,Logistic Models ,Emergency medicine ,Cohort ,Apgar Score ,Apgar score ,Female ,business - Abstract
Understanding and improving obstetrical quality and safety is an important goal of professional societies, and many interventions such as checklists, safety bundles, educational interventions, or other culture changes have been implemented to improve the quality of care provided to obstetrical patients. Although many factors contribute to delivery decisions, a reduced workload has addressed how provider issues such as fatigue or behaviors surrounding impending shift changes may influence the delivery mode and outcomes.The objective was to assess whether intrapartum obstetrical interventions and adverse outcomes differ based on the temporal proximity of the delivery to the attending's shift change.This was a secondary analysis from a multicenter obstetrical cohort in which all patients with cephalic, singleton gestations who attempted vaginal birth were eligible for inclusion. The primary exposure used to quantify the relationship between the proximity of the provider to their shift change and a delivery intervention was the ratio of time from the most recent attending shift change to vaginal delivery or decision for cesarean delivery to the total length of the shift. Ratios were used to represent the proportion of time completed in the shift by normalizing for varying shift lengths. A sensitivity analysis restricted to patients who were delivered by physicians working 12-hour shifts was performed. Outcomes chosen included cesarean delivery, episiotomy, third- or fourth-degree perineal laceration, 5-minute Apgar score of4, and neonatal intensive care unit admission. Chi-squared tests were used to evaluate outcomes based on the proportion of the attending's shift completed. Adjusted and unadjusted logistic models fitting a cubic spline (when indicated) were used to determine whether the frequency of outcomes throughout the shift occurred in a statistically significant, nonlinear pattern RESULTS: Of the 82,851 patients eligible for inclusion, 47,262 (57%) had ratio data available and constituted the analyzable sample. Deliveries were evenly distributed throughout shifts, with 50.6% taking place in the first half of shifts. There were no statistically significant differences in the frequency of cesarean delivery, episiotomy, third- or fourth-degree perineal lacerations, or 5-minute Apgar scores of4 based on the proportion of the shift completed. The findings were unchanged when evaluated with a cubic spline in unadjusted and adjusted logistic models. Sensitivity analyses performed on the 22.2% of patients who were delivered by a physician completing a 12-hour shift showed similar findings. There was a small increase in the frequency of neonatal intensive care unit admissions with a greater proportion of the shift completed (adjusted P=.009), but the findings did not persist in the sensitivity analysis.Clinically significant differences in obstetrical interventions and outcomes do not seem to exist based on the temporal proximity to the attending physician's shift change. Future work should attempt to directly study unit culture and provider fatigue to further investigate opportunities to improve obstetrical quality of care, and additional studies are needed to corroborate these findings in community settings.
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- 2021
29. Validation of pure rotational Raman temperature data from the Raman Lidar for Meteorological Observations (RALMO) at Payerne
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G. Martucci, F. Navas-Guzmán, L. Renaud, G. Romanens, S. M. Gamage, M. Hervo, P. Jeannet, and A. Haefele
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Physics ,Atmospheric Science ,Daytime ,Accuracy and precision ,010504 meteorology & atmospheric sciences ,lcsh:TA715-787 ,lcsh:Earthwork. Foundations ,0211 other engineering and technologies ,02 engineering and technology ,Numerical weather prediction ,01 natural sciences ,Noise (electronics) ,Standard deviation ,lcsh:Environmental engineering ,Troposphere ,Calibration ,lcsh:TA170-171 ,Zenith ,021101 geological & geomatics engineering ,0105 earth and related environmental sciences ,Remote sensing - Abstract
The Raman Lidar for Meteorological Observations (RALMO) is operated at the MeteoSwiss station of Payerne (Switzerland) and provides, amongst other products, continuous measurements of temperature since 2010. The temperature profiles are retrieved from the pure rotational Raman (PRR) signals detected around the 355 nm Cabannes line. The transmitter and receiver systems of RALMO are described in detail, and the reception and acquisition units of the PRR channels are thoroughly characterized. The Fast- Com P7888 card used to acquire the PRR signal, the calculation of the dead time and the desaturation procedure are also presented. The temperature profiles retrieved from RALMO PRR data during the period going from July 2017 to the end of December 2018 have been validated against two reference operational radiosounding systems (ORSs) co-located with RALMO, i.e. the Meteolabor SRS-C50 and the Vaisala RS41. The ORSs have also served to perform the calibration of the RALMO temperature during the validation period. The maximum bias (1Tmax), mean bias ( ) and mean standard deviation ( ) of RALMO temperature Tral with respect to the reference ORS, Tors, are used to characterize the accuracy and precision of Tral along the troposphere. The daytime statistics provide information essentially about the lower troposphere due to lower signal-to-noise ratio. The 1Tmax, and of the differences 1T D Tral-Tors are, respectively, 0.28, 0:02 0:1 and 0:62 0:03 K. The nighttime statistics provide information for the entire troposphere and yield 1Tmax D 0:29 K, D 0:05 0:34K and D 0:66 0:06 K. The small 1Tmax, and values obtained for both daytime and nighttime comparisons indicate the high stability of RALMO that has been calibrated only seven times over 18 months. The retrieval method can correct for the largest sources of correlated and uncorrelated errors, e.g. signal noise, dead time of the acquisition system and solar background. Especially the solar radiation (scattered into the field of view from the zenith angle 8) affects the quality of PRR signals and represents a source of systematic error for the retrieved temperature. An imperfect subtraction of the background from the daytime PRR profiles induces a bias of up to 2K at all heights. An empirical correction f .8/ ranging from 0.99 to 1 has therefore been applied to the mean background of the PRR signals to remove the bias. The correction function f .8/ has been validated against the numerical weather prediction model COSMO (Consortium for Smallscale Modelling), suggesting that f .8/ does not introduce any additional source of systematic or random error to Tral. A seasonality study has been performed to help with understanding if the overall daytime and nighttime zero bias hides seasonal non-zero biases that cancel out when combined in the full dataset., Swiss National Science Foundation (SNSF) European Commission PZ00P2_168114
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- 2021
30. Coordination Chemistry of Heavier Group 13 and 14 Ligands in Transition Metal Complexes
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Burjor Captain and Mohan M. Gamage
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chemistry.chemical_classification ,Transition metal ,chemistry ,Group (periodic table) ,Polymer chemistry ,Coordination complex - Published
- 2021
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31. Single-cell transcriptome analysis of the in vivo response to viral infection in the cave nectar bat Eonycteris spelaea
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Akshamal M. Gamage, Wharton O.Y. Chan, Feng Zhu, Yan Ting Lim, Sandy Long, Matae Ahn, Chee Wah Tan, Randy Jee Hiang Foo, Wan Rong Sia, Xiao Fang Lim, Haopeng He, Weiwei Zhai, Danielle E. Anderson, Radoslaw Mikolaj Sobota, Charles-Antoine Dutertre, and Lin-Fa Wang
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Infectious Diseases ,Plant Nectar ,Virus Diseases ,Chiroptera ,Gene Expression Profiling ,Immunology ,Immunology and Allergy ,Animals ,Single-Cell Analysis ,Transcriptome - Abstract
Bats are reservoir hosts of many zoonotic viruses with pandemic potential. We utilized single-cell transcriptome sequencing (scRNA-seq) to analyze the immune response in bat lungs upon in vivo infection with a double-stranded RNA virus, Pteropine orthoreovirus PRV3M. Bat neutrophils were distinguished by high basal IDO1 expression. NK cells and T cells were the most abundant immune cells in lung tissue. Three distinct CD8
- Published
- 2020
32. Thermal and catalytic decomposition of trans bis-stannyl hyponitrites
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Mohan M Gamage
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- 2020
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33. Thermal and catalytic decomposition of trans bis-stannyl hyponitrites
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M Gamage, Mohan, primary
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- 2020
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34. Thermal and catalytic decomposition of trans bis-stannyl hyponitrites
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M. Gamage, Mohan, primary
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- 2020
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35. Intermediates and catalytic hydrostannylation. Characterization of a rare complex Pt(IPr)[η2-E-(SnBut3)(H)C C(SiMe3)(H)]
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Burjor Captain, Mohan M. Gamage, and Anjaneyulu Koppaka
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010405 organic chemistry ,Ligand ,Stereochemistry ,Organic Chemistry ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Trimethylsilylacetylene ,0104 chemical sciences ,Catalysis ,Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,Yield (chemistry) ,Materials Chemistry ,Physical and Theoretical Chemistry ,Single crystal ,Carbene - Abstract
The complex Pt(IPr)(SnBut3)(H), 1 [IPr=N-heterocylic carbene ligand N,N’-bis-(2,6-(diisopropyl)phenyl)imidazol-2-ylidene] reacts with trimethylsilylacetylene to yield the C-H activation product Pt(IPr)(SnBut3)(κ1-C≡CSiMe3)(H)2, 2. Complex 2 isomerizes to form the unique complex Pt(IPr)[η2-E-(SnBut3)(H)C=C(SiMe3)(H)], 3. This demonstrates that in addition to functioning as a bulky ligand the SnBut3 group can also be actively involved in catalysis. Compound 1 catalyzes the reaction of trimethylsilylacetylene and tri-t-butylstannane at room temperature to afford the selective hydrostannylated product E-(SnBut3)(H)C=C(SiMe3)(H), 4. Structures of all compounds have been determined by single crystal x-ray diffraction analyses.
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- 2017
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36. Investigations of tri-t-butyl tin hydride complexes of transition metals in small molecule activation and catalysis
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Mohan M. Gamage, Sedigheh Etezadi, Burjor Captain, and Anjaneyulu Koppaka
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Steric effects ,010405 organic chemistry ,Hydride ,Ligand ,Organic Chemistry ,010402 general chemistry ,Heterogeneous catalysis ,Photochemistry ,01 natural sciences ,Biochemistry ,Small molecule ,Stannane ,Combinatorial chemistry ,0104 chemical sciences ,Catalysis ,Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,Materials Chemistry ,Reactivity (chemistry) ,Physical and Theoretical Chemistry - Abstract
Transition metal complexes containing the sterically encumbered SnBut3 group are the focus of this brief review. The ability of tin compounds to modify both heterogeneous and homogeneous catalysts has been known for some time. Our recent efforts center on utilizing the reagent But3SnH to investigate the influence of this ligand, which combines a steric profile similar to that of PBut3, with functional reactivity at the Sn-H bond. These properties of the SnBut3 ligand allow preparation of new complexes and comparison of their structures and reactivities with less encumbered trialkyl stannanes. This has allowed fine-tuning of the strained molecular geometry at the coordinatively unsaturated site and study of how that influences small molecule activation. Reversible H2 binding and activation, H2–D2 scrambling to form HD, C-H activation of bound ligands and solvents, catalytic hydrogenation, and catalytic hydrostannylation have all been observed for select complexes. In addition, a range of metal cluster complexes incorporating stannane moieties have been prepared and structurally characterized. The But3SnH ligand provides a new dimension for preparation of new molecular architectures with potential applications in homogeneous and heterogeneous catalysis.
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- 2017
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37. Anti-Cancer Drug HMBA Acts as an Adjuvant during Intracellular Bacterial Infections by Inducing Type I IFN through STING
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Yunn-Hwen Gan, Kok Onn Lee, and Akshamal M. Gamage
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0301 basic medicine ,Cytoplasm ,Burkholderia pseudomallei ,CD14 ,Immunology ,Biology ,Peripheral blood mononuclear cell ,Hexamethylene bisacetamide ,Cell Line ,Microbiology ,Interferon-gamma ,03 medical and health sciences ,0302 clinical medicine ,Immune system ,Adjuvants, Immunologic ,hemic and lymphatic diseases ,Acetamides ,medicine ,Humans ,Immunology and Allergy ,Interferon gamma ,Cells, Cultured ,Interleukin-6 ,Tumor Necrosis Factor-alpha ,Interleukin-8 ,Membrane Proteins ,Salmonella enterica ,Epithelial Cells ,Interleukin-12 ,Nucleotidyltransferases ,030104 developmental biology ,Interferon Type I ,Leukocytes, Mononuclear ,Cancer research ,Interleukin 12 ,Interferon Regulatory Factor-3 ,Tumor necrosis factor alpha ,Intracellular ,Signal Transduction ,030215 immunology ,medicine.drug - Abstract
The anti-proliferative agent hexamethylene bisacetamide (HMBA) belongs to a class of hybrid bipolar compounds developed more than 30 y ago for their ability to induce terminal differentiation of transformed cells. Recently, HMBA has also been shown to trigger HIV transcription from latently infected cells, via a CDK9/HMBA inducible protein-1 dependent process. However, the effect of HMBA on the immune response has not been explored. We observed that pretreatment of human peripheral blood mononuclear cells with HMBA led to a markedly increased production of IL-12 and IFN-γ, but not of TNF-α, IL-6, and IL-8 upon subsequent infection with Burkholderia pseudomallei and Salmonella enterica. HMBA treatment was also associated with better intracellular bacterial control. HMBA significantly improved IL-12p70 production from CD14+ monocytes during infection partly via the induction of type I IFN in these cells, which primed an increased transcription of the p35 subunit of IL-12p70 during infection. HMBA also increased early type I IFN transcription in human monocytic and epithelial cell lines, but this was surprisingly independent of its previously reported effects on positive transcription elongation factor b and HMBA inducible protein-1. Instead, the effect of HMBA was downstream of a calcium influx, and required the pattern recognition receptor and adaptor STING but not cGAS. Our work therefore links the STING-IRF3 axis to enhanced IL-12 production and intracellular bacterial control in primary monocytes. This raises the possibility that HMBA or related small molecules may be explored as therapeutic adjuvants to improve disease outcomes during intracellular bacterial infections.
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- 2017
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38. Immunophenotyping monocytes, macrophages and granulocytes in the Pteropodid bat Eonycteris spelaea
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Feng Zhu, Ying Ying Hey, Randy Foo, Lin-Fa Wang, Charles-Antoine Dutertre, Dolyce H. W. Low, Akshamal M. Gamage, Ian H. Mendenhall, and Matae Ahn
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Lipopolysaccharides ,0301 basic medicine ,Myeloid ,CD14 ,Antigens, Differentiation, Myelomonocytic ,Gene Expression ,lcsh:Medicine ,Receptors, Cell Surface ,Stem cell marker ,Article ,Monocytes ,Immunophenotyping ,Mice ,03 medical and health sciences ,0302 clinical medicine ,Immune system ,Antigens, CD ,Chiroptera ,medicine ,Animals ,Humans ,lcsh:Science ,Phylogeny ,Innate immunity ,Genome ,Multidisciplinary ,Innate immune system ,biology ,Tumor Necrosis Factor-alpha ,Macrophages ,Interleukin-8 ,lcsh:R ,Granulocyte-Macrophage Colony-Stimulating Factor ,Cell Differentiation ,biology.organism_classification ,Mice, Inbred C57BL ,Eonycteris spelaea ,030104 developmental biology ,medicine.anatomical_structure ,Viral infection ,Immunology ,biology.protein ,lcsh:Q ,Antibody ,Granulocytes ,030215 immunology - Abstract
Bats are asymptomatic reservoir hosts for several highly pathogenic viruses. Understanding this enigmatic relationship between bats and emerging zoonotic viruses requires tools and approaches which enable the comparative study of bat immune cell populations and their functions. We show that bat genomes have a conservation of immune marker genes which delineate phagocyte populations in humans, while lacking key mouse surface markers such as Ly6C and Ly6G. Cross-reactive antibodies against CD44, CD11b, CD14, MHC II, and CD206 were multiplexed to characterize circulating monocytes, granulocytes, bone-marrow derived macrophages (BMDMs) and lung alveolar macrophages (AMs) in the cave nectar bat Eonycteris spelaea. Transcriptional profiling of bat monocytes and BMDMs identified additional markers – including MARCO, CD68, CD163, CD172α, and CD88 – which can be used to further characterize bat myeloid populations. Bat cells often resembled their human counterparts when comparing immune parameters that are divergent between humans and mice, such as the expression patterns of certain immune cell markers. A genome-wide comparison of immune-related genes also revealed a much closer phylogenetic relationship between bats and humans compared to rodents. Taken together, this study provides a set of tools and a comparative framework which will be important for unravelling viral disease tolerance mechanisms in bats.
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- 2020
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39. The mechanism of carboxylative cyclization of propargylamine by N-heterocyclic carbene complexes of Au(I)
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Mohan M. Gamage, Carl D. Hoff, Oswaldo Guio, Burjor Captain, Jack V. Davis, Manuel Temprado, Steven P. Nolan, and Tahani Al Chami Al Bayrakdar
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BEARING ,NHC ,CATALYSTS ,010402 general chemistry ,01 natural sciences ,Medicinal chemistry ,Biochemistry ,Adduct ,Inorganic Chemistry ,chemistry.chemical_compound ,CARBON-DIOXIDE ,Carbamic acid ,Materials Chemistry ,Physical and Theoretical Chemistry ,BR ,010405 organic chemistry ,Decarbonylation ,Organic Chemistry ,0104 chemical sciences ,Chemistry ,chemistry ,Yield (chemistry) ,Propargyl ,CL ,Amine gas treating ,Carbonylation ,Carbene - Abstract
The complex [Au(IPr)(2-oxazolidinone)] (1 = IKa) was prepared from reaction of [Au(IPr)Cl] (2), K2CO3, and propargyl amine (PPA). Kinetic studies have been performed for acid cleavage of 1 to yield the oxazolidinone product and an [Au(IPr)(X)] adduct. The fastest rates of cleavage were found to occur for the hydrogen chloride salt of PPA (PPA-HCl) and for the CO2 adduct of PPA, PPA-CO2 = the carbamic acid (CA). This transformation was studied as a function of [CA], pressure of CO2 as well as temperature. Detailed computational studies support the formation of a key intermediate and are also in agreement with a rapid carbonylation/decarbonylation reaction. The computed reactions mechanisms for addition of PPA-HCl and CA are also presented as well as the crystal structure of 1.
- Published
- 2020
40. An Investigation of the Impact of Social Capital for the Entrepreneurial Intentions
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R H G W P K Henegedara and D G M P M Gamage
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entrepreneurial intention ,social capital ,structural capital ,entrepreneurship ,Business Administration - Abstract
It is reported that individuals have less willingness to start their own business. Lack of entrepreneurial intentions impact adversely for the economic development of the country as entrepreneurship is a major source of employment generation and economic development. Thus, scholars emphasize on investigating the factors stimulating the interest of undergraduates to become an entrepreneur. Among the factors, social capital of individuals plays a vital role. On the above backdrop, present study was undertaken to understand the impact of social capital affecting the entrepreneurial intentions of the undergraduates involved in Business Administration and Entrepreneurship courses in Sri Lankan Universities. Findings of the study suggests that the number of social ties, trustworthy relationships and the social norms shared among the undergraduates within their community affect their willingness to start a new business. Thus, the study provides significant insights for the university administrators highlighting importance of facilitating a platform for the undergraduates to network with the fellow undergraduates. R H G W P K Henegedara | D G M P M Gamage "An Investigation of the Impact of Social Capital for the Entrepreneurial Intentions" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd25227.pdf
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- 2019
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41. The Entrepreneurial Intentions among the Undergraduates Involved in Business Administration and Entrepreneurship Courses in Sri Lanka
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D G M P M Gamage and R H G W P K Henegedara
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personality factors ,entrepreneurial ,external factors intentions ,entrepreneurship ,Business Administration - Abstract
Universities play a major role in producing entrepreneurs. Until recently, fostering innovations and new product development through entrepreneurship has not been regarded as a primary task of universities. Although the graduates are given the education on entrepreneurship, it is reported that they have less willingness to start their own business. Lack of entrepreneurial intentions among the undergraduates impact adversely for the economic development of the country as entrepreneurship is a major source of employment generation and economic development. Thus, scholars emphasize more on investigating the factors stimulating the interest of undergraduates to become an entrepreneur. On the above backdrop, present study was undertaken to understand the factors affecting the entrepreneurial intentions of the undergraduates involved in Business Administration and Entrepreneurship courses in Sri Lankan Universities. D G M P M Gamage | R H G W P K Henegedara "The Entrepreneurial Intentions among the Undergraduates Involved in Business Administration and Entrepreneurship Courses in Sri Lanka" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-4 , June 2019, URL: https://www.ijtsrd.com/papers/ijtsrd25175.pdf
- Published
- 2019
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42. Activation of small molecules by the unsaturated complex Pt(IBut)(PBut3): First structural characterization of a peroxycarbonate complex of platinum
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Mark D. Smith, Burjor Captain, and Mohan M. Gamage
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Organic Chemistry ,chemistry.chemical_element ,Trimer ,Biochemistry ,Medicinal chemistry ,Adduct ,Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,Peroxycarbonate ,Materials Chemistry ,Acetone ,Physical and Theoretical Chemistry ,Platinum ,Single crystal ,Carbene ,Phosphine - Abstract
The reaction of Pt(COD)2 with one equivalents of IBut and PBut3 at room temperature yields the unsaturated platinum mixed N-heterocyclic carbene and phosphine complex Pt(IBut)(PBut3), 1. Complex 1 reacts rapidly with O2 and CO to form the dioxygen adduct Pt(IBut)(PBut3)(η2-O2), 2 and Pt3 trimer cluster complex [Pt(IBut)(CO)]3, 3, respectively. Complex 2 further reacts with CO2 at room temperature to give the peroxycarbonate complex Pt(IBut)(PBut3)[η2-OOC(O)O], 4, and the first example characterized by single crystal X-ray diffraction. The reaction of complex 2 with acetone also resulted in the formation of the peroxoacetonate complex Pt(IBut)(PBut3)[η2-OOC(CH3)2O], 5. All the structures for the complexes 1–5 were characterized by X-ray crystallographic studies.
- Published
- 2021
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43. The proteobacterial species Burkholderia pseudomallei produces ergothioneine, which enhances virulence in mammalian infection
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Martin Gengenbacher, Akshamal M. Gamage, Daniel R. X. Lim, Barry Halliwell, Rhonda Sin Ling Chee, Joanne W. K. Ku, Irwin K. Cheah, Yunn-Hwen Gan, Yahua Chen, Cangsong Liao, and Florian P. Seebeck
- Subjects
0301 basic medicine ,biology ,Burkholderia thailandensis ,Burkholderia pseudomallei ,Mutant ,Virulence ,Glutathione ,010402 general chemistry ,biology.organism_classification ,01 natural sciences ,Biochemistry ,0104 chemical sciences ,Microbiology ,03 medical and health sciences ,chemistry.chemical_compound ,030104 developmental biology ,Burkholderia ,chemistry ,Ergothioneine ,Genetics ,Molecular Biology ,Bacteria ,Biotechnology - Abstract
Bacteria use various endogenous antioxidants for protection against oxidative stress associated with environmental survival or host infection. Although glutathione (GSH) is the most abundant and widely used antioxidant in Proteobacteria, ergothioneine (EGT) is another microbial antioxidant, mainly produced by fungi and Actinobacteria. The Burkholderia genus is found in diverse environmental niches. We observed that gene homologs required for the synthesis of EGT are widely distributed throughout the genus. By generating gene-deletion mutants and monitoring production with isotope-labeled substrates, we show that pathogenic Burkholderia pseudomallei and environmental B. thailandensis are able to synthesize EGT de novo. Unlike most other bacterial EGT synthesis pathways described, Burkholderia spp. use cysteine rather than γ-glutamyl cysteine as the thiol donor. Analysis of recombinant EgtB indicated that it is a proficient sulfoxide synthase, despite divergence in the active site architecture from that of mycobacteria. The absence of GSH, but not EGT, increased bacterial susceptibility to oxidative stresses in vitro. However, deletion of EGT synthesis conferred a reduced fitness to B. pseudomallei, with a delay in organ colonization and time to death during mouse infection. Therefore, despite the lack of an apparent antioxidant role in vitro, EGT is important for optimal bacterial pathogenesis in the mammalian host.-Gamage, A. M., Liao, C., Cheah, I. K., Chen, Y., Lim, D. R. X., Ku, J. W. K., Chee, R. S. L., Gengenbacher, M., Seebeck, F. P., Halliwell, B., Gan, Y.-H. The proteobacterial species Burkholderia pseudomallei produces ergothioneine, which enhances virulence in mammalian infection.
- Published
- 2018
44. Defining failed induction of labor
- Author
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William A. Grobman, Jennifer Bailit, Yinglei Lai, Uma M. Reddy, Ronald J. Wapner, Michael W. Varner, John M. Thorp, Kenneth J. Leveno, Steve N. Caritis, Mona Prasad, Alan T.N. Tita, George Saade, Yoram Sorokin, Dwight J. Rouse, Sean C. Blackwell, Jorge E. Tolosa, G. Mallett, M. Ramos-Brinson, A. Roy, L. Stein, P. Campbell, C. Collins, N. Jackson, M. Dinsmoor, J. Senka, K. Paychek, A. Peaceman, M. Talucci, M. Zylfijaj, Z. Reid, R. Leed, J. Benson, S. Forester, C. Kitto, S. Davis, M. Falk, C. Perez, K. Hill, A. Sowles, J. Postma, S. Alexander, G. Andersen, V. Scott, V. Morby, K. Jolley, J. Miller, B. Berg, K. Dorman, J. Mitchell, E. Kaluta, K. Clark, K. Spicer, S. Timlin, K. Wilson, L. Moseley, M. Santillan, J. Price, K. Buentipo, V. Bludau, T. Thomas, L. Fay, C. Melton, J. Kingsbery, R. Benezue, H. Simhan, M. Bickus, D. Fischer, T. Kamon, D. DeAngelis, B. Mercer, C. Milluzzi, W. Dalton, T. Dotson, P. McDonald, C. Brezine, A. McGrail, C. Latimer, L. Guzzo, F. Johnson, L. Gerwig, S. Fyffe, D. Loux, S. Frantz, D. Cline, S. Wylie, J. Iams, M. Wallace, A. Northen, J. Grant, C. Colquitt, D. Rouse, W. Andrews, J. Moss, A. Salazar, A. Acosta, G. Hankins, N. Hauff, L. Palmer, P. Lockhart, D. Driscoll, L. Wynn, C. Sudz, D. Dengate, C. Girard, S. Field, P. Breault, F. Smith, N. Annunziata, D. Allard, J. Silva, M. Gamage, J. Hunt, J. Tillinghast, N. Corcoran, M. Jimenez, F. Ortiz, P. Givens, B. Rech, C. Moran, M. Hutchinson, Z. Spears, C. Carreno, B. Heaps, G. Zamora, J. Seguin, M. Rincon, J. Snyder, C. Farrar, E. Lairson, C. Bonino, W. Smith, K. Beach, S. Van Dyke, S. Butcher, E. Thom, M. Rice, Y. Zhao, P. McGee, V. Momirova, R. Palugod, B. Reamer, M. Larsen, C. Spong, S. Tolivaisa, and J.P. Van Dorsten
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Adult ,medicine.medical_specialty ,Time Factors ,medicine.medical_treatment ,Oxytocin ,Chorioamnionitis ,Article ,Cohort Studies ,03 medical and health sciences ,0302 clinical medicine ,Pregnancy ,Oxytocics ,medicine ,Humans ,Rupture of membranes ,Labor, Induced ,030212 general & internal medicine ,030219 obstetrics & reproductive medicine ,Cesarean Section ,Vaginal delivery ,Obstetrics ,business.industry ,Cephalic presentation ,Postpartum Hemorrhage ,Obstetrics and Gynecology ,medicine.disease ,United States ,Labor induction ,Cohort ,Gestation ,Female ,business ,Cervical Ripening ,medicine.drug - Abstract
BACKGROUND: While there are well-accepted standards for the diagnosis of arrested active-phase labor, the definition of a "failed" induction of labor remains less certain. One approach to diagnosing a failed induction is based on the duration of the latent phase. However, a standard for the minimum duration that the latent phase of a labor induction should continue, absent acute maternal or fetal indications for cesarean delivery, remains lacking. OBJECTIVE: The objective of this study was to determine the frequency of adverse maternal and perinatal outcomes as a function of the duration of the latent phase among nulliparous women undergoing labor induction. METHODS: This study is based on data from an obstetric cohort of women delivering at 25 U.S. hospitals from 2008-2011. Nulliparous women who had a term singleton gestation in the cephalic presentation were eligible for this analysis if they underwent a labor induction. Consistent with prior studies, the latent phase was determined to begin once cervical ripening had ended, oxytocin was initiated and rupture of membranes (ROM) had occurred, and was determined to end once 5 cm dilation was achieved. The frequencies of cesarean delivery, as well as of adverse maternal (e.g., cesarean delivery, postpartum hemorrhage, chorioamnionitis) and perinatal outcomes (e.g., a composite frequency of either seizures, sepsis, bone or nerve injury, encephalopathy, or death), were compared as a function of the duration of the latent phase (analyzed with time both as a continuous measure and categorized in 3-hour increments). RESULTS: A total of 10,677 women were available for analysis. In the vast majority (96.4%) of women, the active phase had been reached by 15 hours. The longer the duration of a woman's latent phase, the greater her chance of ultimately undergoing a cesarean delivery (P
- Published
- 2018
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45. Effect of oral N-acetyl cysteine supplementation in type 2 diabetic patients on intracellular glutathione content and innate immune responses to Burkholderia pseudomallei
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Kok-Onn Lee, Akshamal M. Gamage, and Yunn-Hwen Gan
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Adult ,Male ,Burkholderia pseudomallei ,Melioidosis ,Immunology ,Administration, Oral ,Type 2 diabetes ,Pharmacology ,Microbiology ,Peripheral blood mononuclear cell ,Interferon-gamma ,chemistry.chemical_compound ,Immune system ,medicine ,Humans ,Cells, Cultured ,Aged ,Innate immune system ,biology ,Glutathione ,Middle Aged ,medicine.disease ,biology.organism_classification ,Interleukin-12 ,Immunity, Innate ,Acetylcysteine ,Infectious Diseases ,Diabetes Mellitus, Type 2 ,chemistry ,Female ,Intracellular - Abstract
Type 2 diabetic patients have increased susceptibility to melioidosis, an infectious disease caused by Burkholderia pseudomallei. We had previously shown that peripheral blood mononuclear cells (PBMCs) from diabetic patients with poor glycemic control had a defective IL-12 and IFNγ response to B. pseudomallei infection, resulting in poor intracellular bacterial control. The impaired IL-12 response was due to glutathione (GSH) deficiency characterized by a low reduced to oxidized glutathione ratio (GSH ratio) and could be restored by the addition of reduced GSH to the infected cells. Our goal is to determine whether N-acetyl cysteine (NAC, a GSH pro-drug) supplementation in diabetic patients could improve their immune control of B. pseudomallei. Type 2 diabetic patients with poor glycemic control were given oral supplementation of NAC for six weeks at 1200 mg daily. Their PBMCs and subsets of immune cells showed a significant increase in free GSH concentration. However, the GSH ratio, IL-12 and IFNγ production, and intracellular bacterial killing upon ex-vivo infection did not improve. Thus, oral NAC supplementation in diabetic patients is sufficient to increase intracellular GSH content in blood cells. However, modulating the free GSH content is not sufficient to improve infection outcome as it is the GSH ratio that regulates the IL-12 response in monocytes.
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- 2014
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46. Contrast-Enhanced Differential Mobility-Desorption Electrospray Ionization-Mass Spectrometry Imaging of Biological Tissues
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Facundo M. Fernández, Asiri S. Galhena, Chaminda M. Gamage, and Rachel V. Bennett
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Spectrometry, Mass, Electrospray Ionization ,Analytical chemistry ,Signal-To-Noise Ratio ,010402 general chemistry ,Mass spectrometry ,01 natural sciences ,Mass spectrometry imaging ,Analytical Chemistry ,law.invention ,Ion ,Mice ,Electromagnetic Fields ,Chlorophyta ,law ,Image Processing, Computer-Assisted ,Animals ,Sample preparation ,Image resolution ,Brain Chemistry ,Desorption electrospray ionization ,Chemistry ,010401 analytical chemistry ,Signal Processing, Computer-Assisted ,Plants ,Laser ,Rats ,0104 chemical sciences ,Chemical species - Abstract
Mass spectrometry imaging (MSI) performed under ambient conditions is a convenient and information-rich method that allows for the comprehensive mapping of chemical species throughout biological tissues with typical spatial resolution in the 40-200 μm range. Ambient MSI methods such as desorption electrospray ionization (DESI) eliminate necessary sample preparation but suffer from lower spatial resolution than laser-based and vacuum techniques. In order to take advantage of the benefits of ambient imaging and to compensate for the somewhat limited spatial resolution, a secondary orthogonal separation nested in the imaging scheme was implemented for more selective discernment of tissue features in the spectral domain. Differential mobility spectrometry (DMS), an ion mobility-based separation that selectively transmits ions based on their high-to-low electric field mobility differences, can significantly reduce background chemical interferences, allowing for increased peak capacity. In this work, DESI DM-MSI experiments on biological tissue samples such as sea algae and mouse brain tissue sections were conducted using fixed DMS compensation voltages that selectively transferred one or a class of targeted compounds. By reducing chemical noise, the signal-to-noise ratio was improved 10-fold and the image contrast was doubled, effectively increasing image quality.
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- 2014
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47. Association of volume estimation accuracy obtained using USS, CT and volume calculation formulae for different shaped objects
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I. Abeysekara, Isurani Ilayperuma, L. G. M. Gamage, D. T. K. Gamage, and S. K. Y. I. Kodikara
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Association (object-oriented programming) ,Mathematical analysis ,Volume estimation ,Mathematics ,Volume (compression) - Published
- 2019
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48. Locally aggressive fibrous dysplasia
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T. G. Kashima, Hongtao Ye, S. J. Ostlere, N. M. Gamage, Nicholas A. Athanasou, Maria Fernanda Amary, and Adrienne M. Flanagan
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Adult ,Male ,musculoskeletal diseases ,Pathology ,medicine.medical_specialty ,Cell Cycle Proteins ,Pathology and Forensic Medicine ,law.invention ,Lesion ,Intramedullary rod ,law ,Proto-Oncogene Proteins ,GNAS complex locus ,Humans ,Medicine ,Molecular Biology ,Pathological ,Aged ,Rib cage ,biology ,business.industry ,Fibrous dysplasia ,Cyclin-Dependent Kinase 4 ,Nuclear Proteins ,Soft tissue ,Fibrous Dysplasia of Bone ,Cell Biology ,General Medicine ,Middle Aged ,medicine.disease ,biology.protein ,Osteosarcoma ,Female ,medicine.symptom ,Tomography, X-Ray Computed ,business - Abstract
Although fibrous dysplasia (FD) is a benign fibro-osseous lesion, locally aggressive behaviour has rarely been described but is poorly characterised. In this study, we document clinical, radiological and pathological (including molecular genetics) findings in three cases of locally aggressive FD, two of which involved the ribs. Lesions in these cases, one of which was a recurrent lesion, were followed up for 2-7 years. All of the lesions showed typical histological features of FD but were characterised by extension through the bone cortex into the extra-osseous soft tissue. The lesions did not exhibit overexpression/amplification of CDK4 and MDM2; in two of the cases, a GNAS mutation was identified. Our findings confirm that FD can rarely exhibit locally aggressive behaviour with extension beyond the bone compartment into the surrounding soft tissue; these lesions can be distinguished from low-grade intramedullary osteosarcoma by lack of amplification/overexpression of CDK4 and MDM2 and the presence of a GNAS mutation.
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- 2013
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49. OmniSpect: An Open MATLAB-Based Tool for Visualization and Analysis of Matrix-Assisted Laser Desorption/Ionization and Desorption Electrospray Ionization Mass Spectrometry Images
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Chaminda M. Gamage, Asiri S. Galhena, Facundo M. Fernández, May D. Wang, Rachel V. Bennett, and R. Mitchell Parry
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Spectrometry, Mass, Electrospray Ionization ,Databases, Factual ,Analytical chemistry ,Mass spectrometry ,Article ,Mass spectrometry imaging ,Computational science ,Structural Biology ,Image Processing, Computer-Assisted ,Animals ,MATLAB ,Spectroscopy ,computer.programming_language ,Brain Chemistry ,Desorption electrospray ionization ,Proprietary format ,Chemistry ,Molecular Imaging ,Rats ,Visualization ,Matrix-assisted laser desorption/ionization ,Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization ,Multivariate Analysis ,Mass spectrum ,computer ,Software - Abstract
We present omniSpect, an open source web- and MATLAB-based software tool for both desorption electrospray ionization (DESI) and matrix-assisted laser desorption ionization (MALDI) mass spectrometry imaging (MSI) that performs computationally intensive functions on a remote server. These functions include converting data from a variety of file formats into a common format easily manipulated in MATLAB, transforming time-series mass spectra into mass spectrometry images based on a probe spatial raster path, and multivariate analysis. OmniSpect provides an extensible suite of tools to meet the computational requirements needed for visualizing open and proprietary format MSI data.
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- 2013
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50. Cryogenic Ion Mobility-Mass Spectrometry Captures Hydrated Ions Produced During Electrospray Ionization
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David H. Russell, Chaminda M. Gamage, Joshua A. Silveira, and Kelly A. Servage
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Ions ,Spectrometry, Mass, Electrospray Ionization ,Chemistry ,Ion-mobility spectrometry ,Electrospray ionization ,Temperature ,Analytical chemistry ,Evaporation ,Water ,Field strength ,Mass spectrometry ,Ion source ,Ion ,Physical and Theoretical Chemistry ,Peptides ,Ambient ionization - Abstract
Evaporation of water from extensively hydrated protons and peptides formed by electrospray ionization (ESI) has been examined for the first time by cryogenic ion mobility-mass spectrometry (IM-MS). The extent of hydration was controlled using a heated capillary inlet operated between 340 and 391 K. Cold cluster ions formed in the source region were transported into a low temperature (∼80 K) IM drift tube using an electrostatic ion guide where they were separated on the basis of size-to-charge via low-energy collisions with helium gas. The eluting IM profile was subsequently pulsed into an orthogonal time-of-flight (TOF) mass spectrometer for mass-to-charge (m/z) identification of the cluster ion species. Key parameters that influence the cluster distributions were critically examined including the inlet temperature, drift tube temperature, and IM field strength. In agreement with previous studies, our findings indicate that water evaporation is largely dependent upon the particular charge-carrying species within the cluster. IM-MS results for protonated water clusters suggest that the special stability of H(+)(H(2)O)(n) (n = 21) is attributed to the presence of a compact isomer (assigned to a clathrate cage) that falls below the trendline produced by adjacent clusters in the n = 15 to 35 size range. Peptide studies are also presented in which specific and nonspecific solvation is observed for gramicidin S [GS + 2H](2+)(H(2)O)(n) (n = 0 to ∼26) and bradykinin [BK + 2H](2+)(H(2)O)(n) (n = 0 to ∼73), respectively.
- Published
- 2013
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