Salinization and arsenic contamination of surface water in southwest Bangladesh.

To identify the causes of salinization and arsenic contamination of surface water on an embanked island (i.e., polder) in the tidal delta plain of SW Bangladesh we collected and analyzed water samples in the dry (May) and wet (October) seasons in 2012-2013. Samples were collected from rice paddies (wet season), saltwater ponds used for brine shrimp aquaculture (dry season), freshwater ponds and tidal channels (both wet and dry season), and rainwater collectors. Continuous measurements of salinity from March 2012 to February 2013 show that tidal channel water increases from ~0.15 ppt in the wet season up to ~20 ppt in the dry season. On the polder, surface water exceeds the World Health Organization drinking water guideline of 10 µg As/L in 78% of shrimp ponds and 27% of rice paddies, raising concerns that produced shrimp and rice could have unsafe levels of As. Drinking water sources also often have unsafe As levels, with 83% of tubewell and 43% of freshwater pond samples having >10 µg As/L. Water compositions and field observations are consistent with shrimp pond water being sourced from tidal channels during the dry season, rather than the locally saline groundwater from tubewells. Irrigation water for rice paddies is also obtained from the tidal channels, but during the wet season when surface waters are fresh. Salts become concentrated in irrigation water through evaporation, with average salinity increasing from 0.43 ppt in the tidal channel source to 0.91 ppt in the rice paddies. Our observations suggest that the practice of seasonally alternating rice and shrimp farming in a field has a negligible effect on rice paddy water salinity. Also, shrimp ponds do not significantly affect the salinity of adjacent surface water bodies or subjacent groundwater because impermeable shallow surface deposits of silt and clay mostly isolate surface water bodies from each other and from the shallow groundwater aquifer. Bivariate plots of conservative element concentrations show that all surface water types lie on mixing lines between dry season tidal channel water and rainwater, i.e., all are related by varying degrees of salinization. High As concentrations in dry season tidal channel water and shrimp ponds likely result from groundwater exfiltration and upstream irrigation in the dry season. Arsenic is transferred from tidal channels to rice paddies through irrigation. Including groundwater samples from the same area (Ayers et al. in Geochem Trans 17:1-22, 2016), principal components analysis and correlation analysis reveal that salinization explains most variation in surface water compositions, whereas progressive reduction of buried surface water by dissolved organic carbon is responsible for the nonconservative behavior of S, Fe, and As and changes in Eh and alkalinity of groundwater.

Sources of salinity and arsenic in groundwater in southwest Bangladesh.

BACKGROUND: High salinity and arsenic (As) concentrations in groundwater are widespread problems in the tidal deltaplain of southwest Bangladesh. To identify the sources of dissolved salts and As, groundwater samples from the regional shallow Holocene aquifer were collected from tubewells during the dry (May) and wet (October) seasons in 2012-2013. Thirteen drill cores were logged and 27 radiocarbon ages measured on wood fragments to characterize subsurface stratigraphy. RESULTS: Drill cuttings, exposures in pits and regional studies reveal a >5 m thick surface mud cap overlying a ~30 m thick upper unit of interbedded mud and fine sand layers, and a coarser lower unit up to 60 m thick dominated by clean sands, all with significant horizontal variation in bed continuity and thickness. This thick lower unit accreted at rates of ~2 cm/year through the early Holocene, with local subsidence or compaction rates of 1-3 mm/year. Most tubewells are screened at depths of 15-52 m in sediments deposited 8000-9000 YBP. Compositions of groundwater samples from tubewells show high spatial variability, suggesting limited mixing and low and spatially variable recharge rates and flow velocities. Groundwaters are Na-Cl type and predominantly sulfate-reducing, with specific conductivity (SpC) from 3 to 29 mS/cm, high dissolved organic carbon (DOC) 11-57 mg/L and As 2-258 ug/L, and low sulfur (S) 2-33 mg/L. CONCLUSIONS: Groundwater compositions can be explained by burial of tidal channel water and subsequent reaction with dissolved organic matter, resulting in anoxia, hydrous ferric oxide (HFO) reduction, As mobilization, and sulfate (SO4) reduction and removal in the shallow aquifer. Introduction of labile organic carbon in the wet season as rice paddy fertilizer may also cause HFO reduction and As mobilization. Variable modern recharge occurred in areas where the clay cap pinches out or is breached by tidal channels, which would explain previously measured (14)C groundwater ages being less than depositional ages. Of samples collected from the shallow aquifer, Bangladesh Government guidelines are exceeded in 46 % for As and 100 % for salinity.

Prevalence of, and risk factors for, symptomatic pelvic organ prolapse in Rural Bangladesh: a cross-sectional survey study.

INTRODUCTION AND HYPOTHESIS: The prevalence of symptomatic pelvic organ prolapse (POP), diagnosed by a pre-tested structured questionnaire, is unknown in Bangladesh. We investigated the prevalence of, and risk factors for, symptomatic POP in women in rural Bangladesh, recruited from the community. METHODS: A cross-sectional survey of 787 women aged over 15 years was conducted in four villages in one district in rural Bangladesh. The prevalence of symptomatic POP and the risk factors associated with the condition was investigated, using Chi-squared and multivariate logistic regression. RESULTS: The prevalence of symptomatic POP was 15.6 %. The mean age of participants was 40.1 (±9.0) years. Women aged 35-44 years (odds ratio [OR] 1.96, 95 % confidence interval [CI] 1.03-3.73) and ≥45 years (OR 2.95, 95 % CI 1.62-5.38) were more likely to have POP compared with women aged ≤35 years. Having POP was positively associated with women having ≥5 children (OR 4.34, 95 % CI 1.39-13.58), having chronic obstructive pulmonary disease (COPD; OR 2.07, 95 % CI 1.02-4.21), and women having constipation (OR 3.54, 95 % CI 1.87-6.72). Women whose husband had >5 years of schooling were less likely to have POP (OR 0.37, 95 % CI 0.19-0.73) compared with women whose husband had no schooling. CONCLUSIONS: Symptomatic POP affects a substantial proportion of women in rural Bangladesh and increases with age. Parity, COPD, constipation and husband's education are associated with POP, all of which have the potential to be modified. Thus, interventions targeting these risk factors to prevent the condition are urgently needed in Bangladesh.

Drinking water insecurity: water quality and access in coastal south-western Bangladesh.

National drinking water assessments for Bangladesh do not reflect local variability, or temporal differences. This paper reports on the findings of an interdisciplinary investigation of drinking water insecurity in a rural coastal south-western Bangladesh. Drinking water quality is assessed by comparison of locally measured concentrations to national levels and water quality criteria; resident's access to potable water and their perceptions are based on local social surveys. Residents in the study area use groundwater far less than the national average; salinity and local rainwater scarcity necessitates the use of multiple water sources throughout the year. Groundwater concentrations of arsenic and specific conductivity (SpC) were greater than surface water (pond) concentrations; there was no statistically significant seasonal difference in mean concentrations in groundwater, but there was for ponds, with arsenic higher in the dry season. Average arsenic concentrations in local water drinking were 2-4 times times the national average. All of the local groundwater samples exceeded the Bangladesh guidance for SpC, although the majority of residents surveyed did not perceive their water as having a 'bad' or 'salty' taste.

Trends in the Prevalence of Hypertension and Type 2 Diabetes in Bangladesh (2010-2020): A Systematic Review and Meta-Analysis.

BACKGROUND: The prevalence of cardiovascular diseases (CVDs) and type 2 diabetes mellitus (T2DM) has increased in Bangladesh. This paper has reviewed published studies on hypertension and T2DM from 2010 to 2020 in Bangladesh and conducted a meta-analysis. METHODS: The PubMed database was used for systematic search. Hypertension and T2DM were considered for measuring pooled prevalence by meta-analysis. The random-effects model was used to calculate the pooled prevalence of hypertension (n = 30) and T2DM (n = 21) in relevant studies. The quality of the reviewed studies was determined by sampling strategy, sample size, and outcome assessment. The meta-analysis protocol was registered at PROSPERO (CRD42020206315). RESULTS: The pooled hypertension and T2DM prevalence was 21.6% (95% CI: 18.8%-24.4%) and 13.6% (95% CI: 10.8%-16.5%), respectively. Females were more hypertensive than males (M vs. F: 18.6% vs. 24.8%), and T2DM was higher in females (M vs. F: 12.4% vs. 13.3%). Urban dwellers were more hypertensive and diabetic than rural people (urban vs. rural: 28.5% vs. 20.3% and 18.8% vs. 14.2%, respectively). An 8% increase in the prevalence of hypertension and T2DM became more than double compared to the 1995-2010 period. CONCLUSION: Future research should focus on the underlying factors that increase the prevalence of these diseases and prevention strategies to reduce the trend of increasing prevalence.

Phytochemicals-based targeting RdRp and main protease of SARS-CoV-2 using docking and steered molecular dynamic simulation: A promising therapeutic approach for Tackling COVID-19.

The ongoing COVID-19 pandemic has affected millions of people worldwide and caused substantial socio-economic losses. Few successful vaccine candidates have been approved against SARS-CoV-2; however, their therapeutic efficacy against the mutated strains of the virus remains questionable. Furthermore, the limited supply of vaccines and promising antiviral drugs have created havoc in the present scenario. Plant-based phytochemicals (bioactive molecules) are promising because of their low side effects and high therapeutic value. In this study, we aimed to screen for suitable phytochemicals with higher therapeutic value using the two most crucial proteins of SARS-CoV-2, the RNA-dependent RNA polymerase (RdRp) and main protease (Mpro). We used computational tools such as molecular docking and steered molecular dynamics simulations to gain insights into the different types of interactions and estimated the relative binding forces between the phytochemicals and their respective targets. To the best of our knowledge, this is the first report that not only involves a search for a therapeutic bioactive molecule but also sheds light on the mechanisms underlying target inhibition in terms of calculations of force and work needed to extractthe ligand from the pocket of its target. The complexes showing higher binding forces were subjected to 200 ns molecular dynamic simulations to check the stability of the ligand inside the binding pocket. Our results suggested that isoskimmiwallin and terflavin A are potential inhibitors of RdRp, whereas isoquercitrin and isoorientin are the lead molecules against Mpro. Collectively, our findings could potentially aid in the development of novel therapeutics against COVID-19.

Identification of potent inhibitors against transmembrane serine protease 2 for developing therapeutics against SARS-CoV-2.

In viral binding and entry, the Spike(S) protein of SARS-CoV-2 uses transmembrane serine protease 2 (TMPRSS2) for priming to cleavage themselves. In this study, we have screened 'drug-like' 7476 ligands and found that over thirty ligands can effectively inhibit the TMPRSS-2 better than the control ligand. Finally, the three best drug agents L1, L2, and L6 were selected according to their average binding affinities and fitting score. These ligands interact with Asp435, Cys437, Ser436, Trp461, and Cys465 amino acid residues. The three best candidates and a reported drug Nafamostat mesylate (NAM) were selected to run 250 ns molecular dynamics (MD) simulations. Various properties of ligand-protein interactions obtained from MD simulation such as bonds, angle, dihedral, planarity, coulomb, and van der Waals (VdW) were used for principal component analysis (PCA) calculation. PCA discloses the evidence of the structural similarities to the corresponding complexes of L1, L2, and L6 with the complex of TMPRSS2(TM) and Nafamostat mesylate (TM-NAM). Moreover, Quantitative structure-activity relationship (QSAR) pattern recognition was generated using PCA for the investigation of structural similarities among the selected ligands. Multiple Linear Regression (MLR) model was built to predict the binding energy compared to the binding energy obtained from molecular docking. The MLR regression model reveals an accuracy of 80% for the prediction of the binding energy of ligands. ADMET analysis demonstrates that these drug agents are appeared to be safer inhibitors. These three ligands can be used as potential inhibitors against the TMPRSS2.Communicated by Ramaswamy H. Sarma.

Exploring the Effect of Phyllanthus emblica L. on Cognitive Performance, Brain Antioxidant Markers and Acetylcholinesterase Activity in Rats: Promising Natural Gift for the Mitigation of Alzheimer's Disease.

Neurodegenerative diseases are incurable and debilitating conditions that result in the progressive degeneration of nerve cells, which affect the cognitive activity. Currently, as a result of multiple studies linking Alzheimer's disease (AD) to oxidative damage, the uses of natural antioxidant to prevent, delay, or enhance the pathological changes underlying the progression of AD has received considerable attention. Therefore, this study was aimed at examining the effect of ethanolic extracts of Phyllanthus emblica (EEPE) ripe (EEPEr) and EEPE unripe (EEPEu) fruits on cognitive functions, brain antioxidant enzymes, and acetylcholinesterase (AChE) activity in rat. The effects of EEPEr and EEPEu fruits (i.e., 100 and 200 mg/kg b.w.) were examined in Swiss albino male rats for 12 days and its effect on cognitive functions, brain antioxidant enzymes, and AChE activity determined. Learning and memory enhancing activity of EEPE fruit was examined by using passive avoidance test and rewarded alternation test. Antioxidant potentiality was evaluated by measuring the activity of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase, reduced glutathione (GSH), glutathione-S-transferase, and the contents of thiobarbituric acid reactive substances (TBARS) in entire brain tissue homogenates. AChE activity was determined using colorimetric method. Administration of the highest dose (i.e., 200 mg/kg b.w.) of EEPEr fruit significantly (p < 0.01) and both lowest and highest doses (i.e., 100 and 200 mg/kg b.w.) of EEPEu fruit markedly (p < 0.05, p < 0.001) increased step-through latency in rats on 6th, 11th, and 12th day with respect to the control group. For aforementioned doses, the percentage of memory retention (MR) was considerably (p < 0.05, p < 0.01) increased in rats on 10th, 11th, and 12th days with respect to the control group. The extract, particularly highest dose (i.e., 200 mg/kg b.w.) of EEPEr fruit markedly (p < 0.05) and lowest and highest doses (i.e., 100 and 200 mg/kg b.w.) of EEPEu fruit significantly (p < 0.01) increased the correct responses in rats on 6th, and 12th day related to the control group. In case of this test, the percentage of MR was significantly (p < 0.05, p < 0.01) increased in rats treated with aforementioned doses on 12th day with respect to the control group. The highest dose (i.e., 200 mg/kg b.w.) of EEPEr fruit suggestively (p < 0.05) and both lowest and highest doses (i.e., 100 and 200 mg/kg b.w.) of EEPEu fruit suggestively (p < 0.05, p < 0.01, p < 0.001) increased the levels of SOD, CAT, GSH, GSH-Px and expressively (p < 0.01) decreased the TBARS level compared to the control group. Treatment with the highest dose (i.e., 200 mg/kg b.w.) of EEPEr fruit significantly (p < 0.05) and both lowest and highest doses (i.e., 100 and 200 mg/kg b.w.) of EEPEu fruit markedly (p < 0.01, p < 0.001) decreased the level of AChE activity compared to that of the control group. The present study shows that EEPE fruit possesses an excellent source for natural cognitive enhancer which could be developed in the treatment of AD and other neurodegenerative diseases.