COVID-19 Pandemic: lessons learnt and the way forward

Although the scientific community had been predicting and preparing for a pandemic for the last 10 years, many policy makers did not envision that a virus could cause such devastation to human life, economies and to the social structure. COVID-19 has taught us many bitter lessons and while moving forward it is important to understand that this current pandemic is yet to end. However, COVID-19 is unlikely to be the last pandemic that we face, Due to certain human activities such as urbanization, deforestation, increased human and animal interactions and climate change, we will see more pandemics emerging in the coming years. Preparedness and anticipation of such an event is the only way forward

Development of a Simple Conductivity Meter to Test Soil Electrical Conductivity at the Field Level

Soil salinity is one of the most common problems in agricultural fields. Saline soils reduce crop yield. The most common method for testing soil salinity is the test of Electrical Conductivity (EC) of a given soil solution by using a soil conductivity meter. Many farmers are unaware of their soil salinity because soil testing facilities are not available at the field level in Sri Lanka. Therefore, a requirement for a simple conductivity meter that can be used in the field is high. Thus, in this study, the aim is to develop a simple soil electrical conductivity meter by using a D400 transistor, 50K volume control, and an LED. The developed simple soil electrical conductivity meter was calibrated using standard KCl s Soil salinity is one of the most common problems in agricultural fields. Saline soils reduce crop yield. The most common method for testing soil salinity is the test of Electrical Conductivity (EC) of a given soil solution by using a soil conductivity meter. Many farmers are unaware of their soil salinity because soil testing facilities are not available at the field level in Sri Lanka. Therefore, the requirement for a simple conductivity meter that can be used in the field is high. Thus, in this study, the aim is to develop a simple soil electrical conductivity meter by using a D400 transistor, 50K volume control, and an LED. The developed simple soil electrical conductivity meter was calibrated using standard KCl solutions with conductivities of 0.2 ms/m and 0.4 ms/m respectively. Finally, the EC of eighteen soil samples around Sri Lanka was tested using a laboratory soil conductivity meter (Spectrum Tech. ECTestr 11+) and the developed simple conductivity meter. Our results indicate that this simple conductivity meter works well with Sri Lankan soil and could be promoted among farmers to test and increase awareness about soil salinity. olutions with the conductivities of 0.2 ms/m and 0.4 ms/m respectively. Finally, the EC of eighteen soil samples around Sri Lanka was tested using a laboratory soil conductivity meter (Spectrum Tech. ECTestr 11+) and the developed simple conductivity meter. Our results indicate that this simple conductivity meter works well with Sri Lankan soil and could be promoted among farmers to test and increase awareness about soil salinity

Screening of five Sri Lankan endemic plants for anti-cancer effects on breast cancer stem cells isolated from MCF-7 and MDA-MB-231 cell lines

Purpose: To screen selected endemic plants grown in Sri Lanka on breast cancer stem cells (bCSCs) for their anti-cancer propertiesMethods: Breast-CSCs expressing CD24-/CD44+ surface markers were isolated from MDA-MB-231 cells by magnetic-assisted cell sorting method and validated using flow cytometry. A panel of forty extracts from barks and leaves of Doona nervosa, Garcinia quaesita, Garcinia zeylanica, Memecylon rostratum and Schumacheria castaneifolia were obtained by sequential solvent extraction and tested on bCSC-mammospheres derived from MDA-MB-231 and MCF-7 cells and normal mammary epithelial (MCF-10A) cells. Proliferation and cell stemness were analyzed using WST-1 cell proliferation assay and alkaline phosphatase assay.Results: Hexane and chloroform extracts of G. zeylanica and G. quaesita barks showed dosedependent reduction in proliferation and stemness in both bCSCs tested with less effect on MCF-10A cells. Hexane, chloroform and ethyl acetate extracts of S. castaneifolia bark selectively inhibited mammospheres of triple negative bCSCs cells.Conclusion: This study demonstrates that the non-polar extracts of G. zeylanica and G. quaesita, S. castaneifolia barks inhibit the proliferation of bCSCs of triple negative and estrogen-progesterone positive breast cancers. Findings of the present study may useful for developing a future anti-cancer therapeutics which can target bCSCs.Keywords: Cancer stem cells, Garcinia zeylanica, Garcinia quaesita, Schumacheria castaneifolia, Mammosphere

Viral load, clinical disease severity and cellular immune responses in primary varicella zoster virus infection in Sri Lanka

Background In Sri Lanka, varicella zoster virus (VZV) is typically acquired during adulthood with significant associated disease morbidity and mortality. T cells are believed to be important in the control of VZV replication and in the prevention of reactivation. The relationship between viral load, disease severity and cellular immune responses in primary VZV infection has not been well studied. Methodology We used IFNγ ELISpot assays and MHC class II tetramers based on VZV gE and IE63 epitopes, together with quantitative real time PCR assays to compare the frequency and phenotype of specific T cells with virological and clinical outcomes in 34 adult Sri Lankan individuals with primary VZV infection. Principal Findings Viral loads were found to be significantly higher in patients with moderate to severe infection compared to those with mild infection (p<0.001) and were significantly higher in those over 25 years of age (P<0.01). A significant inverse correlation was seen between the viral loads and the ex vivo IFNγ ELISpot responses of patients (P<0.001, r = −0.85). VZV-specific CD4+ T cells expressed markers of intermediate differentiation and activation. Conclusions Overall, these data show that increased clinical severity in Sri Lankan adults with primary VZV infection associates with higher viral load and reduced viral specific T cell responses

Transmission dynamics, clinical characteristics and sero-surveillance in the COVID-19 outbreak in a population dense area of Colombo, Sri Lanka April- May 2020

Background The transmission dynamics of SARS-CoV-2 varies depending on social distancing measures, circulating SARS-CoV-2 variants, host factors and other environmental factors. We sought to investigate the clinical and epidemiological characteristics of a SARS-CoV-2 outbreak that occurred in a highly dense population area in Colombo, Sri Lanka from April to May 2020. Methodology/principal findings We carried out RT-qPCR for SARS-CoV2, assessed the SARS-CoV-2 specific total and neutralizing antibodies (Nabs) in a densely packed, underserved settlement (n = 2722) after identification of the index case on 15th April 2020. 89/2722 individuals were detected as infected by RT-qPCR with a secondary attack rate among close contacts being 0.077 (95% CI 0.063–0.095). Another 30 asymptomatic individuals were found to have had COVID-19 based on the presence of SARS-CoV-2 specific antibodies. However, only 61.5% of those who were initially seropositive for SARS-CoV-2 had detectable total antibodies at 120 to 160 days, while only 40.6% had detectable Nabs. 74/89 (83.1%) of RT-qPCR positive individuals were completely asymptomatic and all 15 (16.9%) who experienced symptoms were classified as having a mild illness. 18 (20.2%) were between the ages of 61 to 80. 11/89 (12.4%) had diabetes, 8/89 (9%) had cardiovascular disease and 4 (4.5%) had asthma. Of the two viruses that were sequenced and were of the B.1 and B.4 lineages with one carrying the D614G mutation. Discussion/conclusion Almost all infected individuals developed mild or asymptomatic illness despite the presence of comorbid illnesses. Since the majority of those who were in this underserved settlement were not infected despite circulation of the D614G variant, it would be important to further study environmental and host factors that lead to disease severity and transmission

Development and validation of an in house multiplex real time PCR for quantification of all four serotypes of dengue virus

Objectives: In order to determine the infecting dengue virus (DENV) serotype and also to quantify the amount of virus in clinical samples and cell cultures, we proceeded to optimize and validate a quantitative real time RT-PCR assay.Methods: WHO reference strains of the four DENV serotypes were cultured on C6/36 cell lines for 7 days. The supernatants were used to determine plaque forming units (pfus) using BHK cell lines, which is indicative of infecting virus particles. cDNA was synthesized from RNA extracted from the virus culture supernatants. A tenfold dilution series (106 to 101 pfu/ml) of the known pfus of the viruses was prepared using the cDNA for standard curves. Data were analyzed using applied biosystems sequence detection systems. The threshold cycle value (Ct) for each reaction was determined by manually setting the threshold limit. Each standard curve was initially generated individually and later was used in a multiplex assay. All experiments were done in triplicate.Results: The optimized multiplex method detected all four DENV serotypes and generated standard curves with correlation coefficients (R2 values) above 0.95, which suggested that the standard curves and dilutions were of acceptable quality. The slope values of the standard curves were between -3.1 and -3.8 for all assays, implying that the PCR reactions were quite efficient.Conclusions: We have optimized and validated a multiplex quantitative real time RT-PCR assay, which can be effectively used to determine the infecting DENV in samples and also quantify the amount of virus

Diagnosis of erectile dysfunction can be used to improve screening for Type 2 diabetes mellitus.

AIMS: To assess the diagnostic accuracy of four undiagnosed Type 2 diabetes mellitus risk scores accounting for erectile dysfunction status. METHODS: This was a population-based cross-sectional study. Type 2 diabetes was defined according to a oral glucose tolerance test and self-reported physician diagnosis. Erectile dysfunction was defined according to the answer to the question, 'Have you had difficulties obtaining an erection in the last 6 months?' (yes/no). The risk scores used were the FINDRISC, LA-FINDRISC, American Diabetes Association score and the Peruvian Risk Score. A Poisson regression model was fitted to assess the association between Type 2 diabetes and erectile dysfunction. The area under the receiver-operating characteristic curve was estimated overall and by erectile dysfunction status. RESULTS: A total of 799 men with a mean (sd) age of 48.6 (10.7) years were included in the study. The overall prevalence of Type 2 diabetes was 9.3%. Compared with healthy men, men with Type 2 diabetes had 2.71 (95% CI 1.57-4.66) higher chances of having erectile dysfunction. Having excluded men aware of Type 2 diabetes status (N=38), the area under the receiver-operating characteristic curve of three of the risk scores (not the American Diabetes Association score) improved among those who had erectile dysfunction in comparison with those who did not; for example, the area under the receiver-operating characteristic curve of the LA-FINDRISC score was 89.6 (95% CI 78.7-99.9) in men with erectile dysfunction and 76.5 (95% CI 68.5-84.4) overall. CONCLUSIONS: In a population-based study, erectile dysfunction was more common in men with Type 2 diabetes than in the otherwise healthy men. Screening for erectile dysfunction before screening for Type 2 diabetes seems to improve the accuracy of well-known risk scores for undiagnosed Type 2 diabetes