Medicine
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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty
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Item Nano-osmolyte conjugation: Tailoring the osmolyte-protein interactions at the nanoscale(American Chemical Society, 2023) Sharma, H.; Dar, T.A.; Wijayasinghe, Y.S.; Sahoo, D.; Poddar, N.K.Osmolytes are small organic compounds accumulated at higher concentrations in the cell under various stress conditions like high temperature, high salt, high pressure, etc. Osmolytes mainly include four major classes of compounds including sugars, polyols, methylamines, and amino acids and their derivatives. In addition to their ability to maintain protein stability and folding, these osmolytes, also termed as chemical chaperones, can prevent protein misfolding and aggregation. Although being efficient protein folders and stabilizers, these osmolytes exhibit certain unavoidable limitations such as nearly molar concentrations of osmolytes being required for their effect, which is quite difficult to achieve inside a cell or in the extracellular matrix due to nonspecificity and limited permeability of the blood-brain barrier system and reduced bioavailability. These limitations can be overcome to a certain extent by using smart delivery platforms for the targeted delivery of osmolytes to the site of action. In this context, osmolyte-functionalized nanoparticles, termed nano-osmolytes, enhance the protein stabilization and chaperone efficiency of osmolytes up to 105 times in certain cases. For example, sugars, polyols, and amino acid functionalized based nano-osmolytes have shown tremendous potential in preventing protein aggregation. The enhanced potential of nano-osmolytes can be attributed to their high specificity at low concentrations, high tunability, amphiphilicity, multivalent complex formation, and efficient drug delivery system. Keeping in view the promising potential of nano-osmolytes conjugation in tailoring the osmolyte-protein interactions, as compared to their molecular forms, the present review summarizes the recent advancements of the nano-osmolytes that enhance the protein stability/folding efficiency and ability to act as artificial chaperones with increased potential to prevent protein misfolding disorders. Some of the potential nano-osmolyte aggregation inhibitors have been highlighted for large-scale screening with future applications in aggregation disorders. The synthesis of nano-osmolytes by numerous approaches and future perspectives are also highlighted.Item Advances in surface plasmon resonance biosensors for medical diagnostics: An overview of recent developments and techniques(Elsevier, 2023) Janith, G.I.; Herath, H.S.; Hendeniya, N.; Attygalle, D.; Amarasinghe, D.A.S.; Logeeshan, V.; Wickramasinghe, P.M.T.B.; Wijayasinghe, Y.S.Over the last two decades, surface plasmon resonance (SPR) sensors have advanced significantly, becoming an important tool in disciplines such as biosensing, chemical sensing, and material characterization. SPR has gained popularity in biosensing because of its great sensitivity and specificity in detecting biomolecular interactions. This review provides an overview of the recent developments of the SPR biosensor technology and its applications in medical diagnostics. To provide an up-to-date overview of the area, the review includes the most recent works from the last decade. Furthermore, it explores various configurations (prism, grating, fiber optic, waveguidemodulated) and wave properties (angle, wavelength, phase) being tracked for sensing together withstrategies for enhancing sensitivity and selectivity through mechanisms such as surface coatings, sensing mediums, and immobilization techniques.Item Implications of trimethylamine N-oxide (TMAO) and betaine in human health: beyond being osmoprotective compounds(Frontiers Media, 2022) Ilyas, A.; Wijayasinghe, Y.S.; Khan, I.; Samaloty, N.M.E.; Adnan, M.; Dar, T.A.; Poddar, N.K.; Singh, L.R.; Sharma, H.; Khan, S.Osmolytes are naturally occurring small molecular weight organic molecules, which are accumulated in large amounts in all life forms to maintain the stability of cellular proteins and hence preserve their functions during adverse environmental conditions. Trimethylamine N-oxide (TMAO) and N,N,N-trimethylglycine (betaine) are methylamine osmolytes that have been extensively studied for their diverse roles in humans and have demonstrated opposing relations with human health. These osmolytes are obtained from food and synthesized endogenously using dietary constituents like choline and carnitine. Especially, gut microbiota plays a vital role in TMAO synthesis and contributes significantly to plasma TMAO levels. The elevated plasma TMAO has been reported to be correlated with the pathogenesis of numerous human diseases, including cardiovascular disease, heart failure, kidney diseases, metabolic syndrome, etc.; Hence, TMAO has been recognized as a novel biomarker for the detection/prediction of several human diseases. In contrast, betaine acts as a methyl donor in one-carbon metabolism, maintains cellular S-adenosylmethionine levels, and protects the cells from the harmful effects of increased plasma homocysteine. Betaine also demonstrates antioxidant and antiinflammatory activities and has a promising therapeutic value in several human diseases, including homocystinuria and fatty liver disease. The present review examines the multifarious functions of TMAO and betaine with possible molecular mechanisms towards a better understanding of their emerging and diverging functions with probable implications in the prevention, diagnosis, and treatment of human diseases.Item Sirtuins as potential therapeutic targets for mitigating neuroinflammation associated with Alzheimer's disease(Frontiers Research Foundation,Lausanne, Switzerland, 2021) Fernando, K.K.M.; Wijayasinghe, Y.S.Alzheimer's disease (AD) is the most common neurodegenerative disorder, which is associated with memory deficit and global cognitive decline. Age is the greatest risk factor for AD and, in recent years, it is becoming increasingly appreciated that aging-related neuroinflammation plays a key role in the pathogenesis of AD. The presence of β-amyloid plaques and neurofibrillary tangles are the primary pathological hallmarks of AD; defects which can then activate a cascade of molecular inflammatory pathways in glial cells. Microglia, the resident macrophages in the central nervous system (CNS), are the major triggers of inflammation; a response which is typically intended to prevent further damage to the CNS. However, persistent microglial activation (i.e., neuroinflammation) is toxic to both neurons and glia, which then leads to neurodegeneration. Growing evidence supports a central role for sirtuins in the regulation of neuroinflammation. Sirtuins are NAD+-dependent protein deacetylases that modulate a number of cellular processes associated with inflammation. This review examines the latest findings regarding AD-associated neuroinflammation, mainly focusing on the connections among the microglial molecular pathways of inflammation. Furthermore, we highlight the biology of sirtuins, and their role in neuroinflammation. Suppression of microglial activity through modulation of the sirtuin activity has now become a key area of research, where progress in therapeutic interventions may slow the progression of Alzheimer's disease.Item Comparison of four low-cost carbapenemase detection tests and a proposal of an algorithm for early detection of carbapenemase-producing Enterobacteriaceae in resource-limited settings(Public Library of Science, 2021) Kumudunie, W.G.M.; Wijesooriya, L.I.; Wijayasinghe, Y.S.ABSTRACT: Rapidly progressing antibiotic resistance is a great challenge in therapy. In particular, the infections caused by carbapenem-resistant Enterobacteriaceae (CRE) are exceedingly difficult to treat. Carbapenemase production is the predominant mechanism of resistance in CRE. Early and accurate identification of carbapenemase-producing carbapenem-resistant Enterobacteriaceae (CP-CRE) is extremely important for the treatment and prevention of such infections. In the present study, four phenotypic carbapenemase detection tests were compared and an algorithm was developed for rapid and cost-effective identification of CP-CRE. A total of 117 Enterobacteriaceae (54 CP-CRE, 3 non-CP-CRE, and 60 non-CRE) isolates were tested for carbapenemase production using modified Hodge test (MHT), modified carbapenem inactivation method (mCIM), Carba NP test (CNPt), and CNPt-direct test. The overall sensitivity/specificity values were 90.7%/92.1% for MHT, 100%/100% for mCIM, 75.9%/100% for CNPt, and 83.3%/100% for CNPt-direct. OXA-48-like enzymes were detected with 93.2% sensitivity by MHT and >77.3% sensitivity by two Carba NP tests. MHT could only detect half of the NDM carbapenemase producers. CNPt-direct exhibited enhanced sensitivity compared to CNPt (100% vs 25%) for detection of NDM producers. Considering these findings we propose CNPt-direct as the first test followed by mCIM for rapid detection of CP-CRE. With this algorithm >80% of the CP-CRE could be detected within 24 hours from the time the sample is received and 100% CP-CRE could be detected in day two. In conclusion, mCIM was the most sensitive assay for the identification of CP-CRE. CNPt-direct performed better than CNPt. An algorithm consisting CNPt-direct and mCIM allows rapid and reliable detection of carbapenemase production in resource-limited settings.Item In vitro anti-diabetic effects and phytochemical profiling of novel varieties of Cinnamomum zeylanicum (L.) extracts(Corte Madera, 2020) Niroshani, W.A.; Wariyapperuma, M.; Kannangara, S.; Wijayasinghe, Y.S.; Subramanium, S.; Jayawardena, B.BACKGROUND: Diabetes mellitus type 2 (DMT2) is a leading metabolic disorder in the world. Anti-diabetic actions of phytochemicals from various medicinal herbs have been explored as an alternative therapy in the management of DMT2 due to adverse effects of synthetic drugs used in allopathic medicine. α-amylase and α-glucosidase inhibitory potential and phytochemical profiling were investigated in aqueous extracts of two new Cinnamomum zeylanicum accessions, namely C. zeylanicum Sri Wijaya (SW), C. zeylanicum Sri Gemunu (SG) and commercially available C. zeylanicum (CC). METHODS: Microwave Digestion (MD), Pressurized Water Extraction (PWE), Steam Distillation (SD), Solvent Extraction (SE), Decoction Water Extraction (DWE) and Infusion Water Extraction (IWE) methods were used to prepare Cinnamon quill extracts. Total phenolic content (TPC, Folin-Ciocalteu method) and Proanthocyanidin content (PC, vanillin assay), α-amylase and α-glucosidase inhibition of Cinnamon extracts were determined spectrophotometrically. The α-amylase and α-glucosidase inhibition were reported in terms of IC50 value. The phytochemical profiling was accomplished by GC-MS technique. RESULTS AND DISCUSSION: Lowest IC50 values were observed in PWE and DWE of SW. The highest PC and TPC were also observed in PWE and DWE of SW. Pressured water and decoctions are promising methods for the extraction of antidiabetic constituents from cinnamon. Benzoic acid, cinnamyl alcohol, benzyl alcohol, and 4-Allyl-2,6-dimethoxyphenol were identified as major compounds in SW extracts. These compounds are believed to be responsible for strong enzyme inhibitory activity of the extracts. CONCLUSIONS: This is the first study to explore the use of pressured and decoctions water to extract anti-diabetic phytochemicals from cinnamon. The extensive metabolite profiling of novel SW and SG extracts and comparison of that with commercially available CC are reported for the first time in this study. The C. zeylanicum, SW accession holds some promise in the management of diabetes. KEYWORDS: Cinnamomum zeylanicum; Decoction water extraction; Diabetes mellitus type 2; GC-MS; Pressurized Water Extraction; Sri Wijaya; α-amylase; α-glucosidase.Item Epidemiology of multidrug-resistant Enterobacteriaceae in Sri Lanka: First evidence of bla KPC harboring Klebsiella pneumoniae.(Elsevier., 2020) Kumudunie, W.G.M.; Wijesooriya, L.I.; Namalie, K.D.; Sunil-Chandra, N.P.; Wijayasinghe, Y.S.BACKGROUND: Extended-spectrum β-lactamase producing Enterobacteriaceae (ESBL-PE) and carbapenem-resistant Enterobacteriaceae (CRE) are disseminated worldwide posing a serious public health concern. Although, the presence of ESBL-PE and CRE in Sri Lanka has been reported, the prevalence is unknown. This study aimed to provide up-to-date epidemiological data on multidrug-resistant Enterobacteriaceae and to characterize the molecular determinants of carbapenemase-producing Enterobacteriaceae (CPE) in Sri Lanka.METHODS: A prospective cross-sectional study was conducted at a tertiary care hospital in Sri Lanka between December 2017 and February 2018. ESBL-PE and CRE were identified by disc diffusion method. Carbapenemase production was determined by carbapenem inactivation method and the presence of selected carbapenemase genes were detected by PCR. RESULTS: Five hundred and ninety-three Enterobacteriaceae were isolated from variety of clinical samples. Overall prevalence of ESBL-PE and CRE were 26.0% (n = 154) and 9.6% (n = 57), respectively. The highest rate of ESBL-PE (30.8%) was found in urine samples, while the highest occurrence of CRE (20.8%) was seen in respiratory specimens. The most common CRE species identified was K. pneumoniae (n = 46, 80.7%), followed by C. freundii (n = 4, 7.0%), E. coli (n = 3, 5.3%), P. rettgeri (n = 2, 3.5%), E. cloacae (n = 1, 1.7%), and K. aerogenes (n = 1, 1.7%). Carbapenemase production was observed in 54 (94.7%) of CRE isolates. Fifty eight carbapenemase encoding genes were identified in 54 CPE. The most prevalent carbapenemase gene was blaOXA-48-like (n = 48, 88.9%), followed by blaNDM (n = 8, 14.8%), and blaKPC (n = 2, 3.7%). CONCLUSIONS: This study reports an alarming rate of CRE and the emergence of blaKPC harboring K. pneumoniae in Sri Lanka. The need for preventive measures is highlighted to limit the spread of these difficult-to-treat bacteria in the country. KEYWORDS: Carbapenem resistance; Carbapenemase; ESBL; Enterobacteriaceae; KPC; Sri Lanka.Item Comparison of Three Carbapenemase Producing Enterobacteria (CPE) Detection Methods(19th Conference on Postgraduate Research, International Postgraduate Research Conference 2018, Faculty of Graduate Studies,University of Kelaniya, Sri Lanka, 2018) Kumudunie, W.G.M.; Wijayasinghe, Y.S.; Wijesooriya, W.R.P.L.I.; Sunil-Chandra, N.P.; Namalie, K.D.Introduction: The emergence of carbapenem resistant enterobacteria (CRE) is a critical and growing health threat, causing a failure of almost all the available antibiotics and limiting the effective therapeutic options. CRE has been reported all over the world including Sri Lanka. The carbapenem resistance in enterobacteria is mainly occurred due to the production of carbapenemases, the carbapenem inactivating enzymes. Therefore, accurate and timely detection of CPE is an important aspect to streamline the empiric antibiotic therapy. In this study, three CPE detection methods namely, Carba NP-rapid biochemical test, modified carbapenem inhibition method (MCIM) and modified Hodge test (MHT) were compared for the detection of CPE. Carba NP test is a rapid biochemical test that requires 2 hours or less. However, both MCIM and MHT require incubation of 18 – 24 hours. Objective: To compare theCarba NP-rapid biochemical test with the MCIM and MHT for the detection of CPE. Methodology: Fifty-eight clinically significant CRE isolates were recovered from clinical specimens from patients attended to North Colombo Teaching Hospital (NCTH)during December 2017 – February 2018. Antibiotic sensitivity testing for the screening of CRE was performed according to Clinical and Laboratory Standards Institute (CLSI) guidelines. Enterobacteria, resistant to at least one carbapenem antibiotic were considered as CRE. Carba NP test, MCIM and MHT were carried out for CRE isolates according to the CLSI guidelines. Statistical analysis was done using R programming language (level of significance P<0.05). Results: Of 58 CRE, 94.82% (55/58) were confirmed as CPE via both MCIM and MHT while 77.58% (45/58) were revealed as CPE by Carba NP test. There was a significant reduction of CPE detection by Carba NP method compared to MCIM and MHT(P=0.007). Conclusion: Of the three CPE detection methods, sensitivity was higher in MCIM and MHT compared to Carba NP – rapid biochemical test. Acknowledgement: Financial assistance by National Research Council, Sri Lanka (NRC 17-055) is acknowledged.Item Producing proficient methyl donors from alternative substrates of S - Adenosylmethioninesynthetase(Bethesda, Md. : American Physiological Society, 2014) Wijayasinghe, Y.S.; Blumenthal, R.M.; Viola, R.E.