The Crystal Structures of Some o-Halogeno-Aroyl Compounds and of a Palmarin Derivative

This thesis is divided mainly into three sections (see outline): the first section is a brief description of the theory and methods of x-ray crystal structure analysis, the second section describes the crystal structures of four o-halogeno-aroyl compounds and the third one includes the structure of a palmarin derivative. There are two appendices in the thesis. The first one is a brief account of the unsuccessful attempt to solve the structure of phorbol and the second being the improvement of the existing apparatus for Nonius Weissenberg cameras to collect photographic data at low temperature. Section I is divided under nine broad headings giving a short review of the crystal geometry, theory and methods of x-ray crystal structure analysis, refinement of atomic parameters and evaluation of the accuracy of the final results. There are five chapters in Section II. The crystal structure of o-chlorobenzoylacetylene and o-bromobenzoylacetylene are described in the Chapters 1 and 2 respectively. Intramolecular overcrowding and intermolecular ethynyl hydrogen bonds are present in both the structures. Chapter 3 contains the structure of o-fluorobenzoic acid and that of 2-chloro-1,8-phthaloylnaphthalene is described in Chapter 4. The detailed findings of the characteristic features of the conformation, intermolecular hydrogen bonding and intramolecular overcrowding in different o-halogeno-aroyl compounds are discussed in Chapter 5. The crystal structure analysis of p-bromophenacyl derivative of palmarin is described in Section III. The confirmation of the B-epoxide configuration of the palmarin derivative has decided the configuration of the epoxide in a series of Colombo root bitter principleshaving composition C20H22O7 (palmarin, jateorin and chasmanthin) . The structure analysis has also revealed the special distortion of the molecule. A brief account of the unfruitful attempt to solve the structure of phorbol, a natural product, using three different solvate derivatives is given in Appendix A. The short description of the arrangement for taking photographs in the cold nitrogen atmosphere can be seen in Appendix B

Bacterial Community Profiling of Tropical Freshwaters in Bangladesh

Seasonal and spatial variations in the bacterial communities of two tropical freshwater sources in Bangladesh, Lake Dhanmondi in central Dhaka, and a pond in the outskirts of Dhaka, were assessed and compared using PCR-DGGE and deep sequencing of 16S rRNA genes, as well as heterotrophic enrichments using water samples collected at nine different time points during 1 year. Temporal and spatial variations of common aquatic bacterial genera were observed, but no clear seasonal variations could be depicted. The major bacterial genera identified from these two sites were members of the Proteobacteria, Cyanobacteria, Actinobacteria, Bacteroidetes, Chlorobi, Chloroflexi, Verrucomicrobia, and Firmicutes. Among the proteobacterial groups, members of the α-, β-, and γ- Proteobacteria predominated. γ- Proteobacteria belonging to the Escherichia coli/Shigella group even the diarrheagenic pathotypes of E. coli e.g., EPEC and ETEC were detected in most samples throughout the year, with no apparent correlations with other microbial groups. The other pathotypes, EHEC, EAEC, and EIEC/Shigella spp. were also detected occasionally. This study represents the first thorough analysis of the microbial diversity of tropical freshwater systems in Bangladesh.publishedVersio

The 2008 Cholera Epidemic in Zimbabwe: Experience of the icddr,b Team in the Field

During August 2008–June 2009, an estimated 95,531 suspected cases of cholera and 4,282 deaths due to cholera were reported during the 2008 cholera outbreak in Zimbabwe. Despite the efforts by local and international organizations supported by the Zimbabwean Ministry of Health and Child Welfare in the establishment of cholera treatment centres throughout the country, the case-fatality rate (CFR) was much higher than expected. Over two-thirds of the deaths occurred in areas without access to treatment facilities, with the highest CFRs (>5%) reported from Masvingo, Manicaland, Mashonaland West, Mashonaland East, Midland, and Matabeleland North provinces. Some factors attributing to this high CFR included inappropriate cholera case management with inadequate use of oral rehydration therapy, inappropriate use of antibiotics, and a shortage of experienced healthcare professionals. The breakdown of both potable water and sanitation systems and the widespread contamination of available drinking-water sources were also considered responsible for the rapid and widespread distribution of the epidemic throughout the country. Training of healthcare professionals on appropriate cholera case management and implementation of recommended strategies to reduce the environmental contamination of drinking-water sources could have contributed to the progressive reduction in number of cases and deaths as observed at the end of February 2009

Potencies of Justicia adhatoda L. for its possible phytotoxic activity

The phytotoxic effects of Justicia adhatoda L. were investigated on cauliflower, broccoli, tomato, foxtail millet and barnyard grass. The experiments were carried out under laboratory and in pot experiments. Six different aqueous methanol extract concentrations (control, 0.001, 0.003, 0.01, 0.03 and 0.1 g DW equivalent mL-1 extract) were tested in the laboratory and six aqueous extract concentrations (control, 1.0, 2.0, 3.0, 4.0 and 5.0 g DW mL-1 extract equivalent) were evaluated in the pot experiment. Results showed a reduction in germination and growth (shoot length, root length and biomass weight) at higher extract concentration compared to control. The leaf extracts from J. adhatoda showed that the foxtail millet and barnyard grass are germinating below 50 % both in the laboratory condition and in the pot experiment at their maximum concentration. When maximum extracts have been applied, we have found less than 0.5 cm of shoot and root of foxtail millet and barnyard grass. Maximum dry weight reduction was observed in foxtail millet and barnyard grass at the same concentration. The findings show that J. adhatoda may have phytotoxic potential and thus contains phytotoxins. Therefore, J. adhatoda can be used in sustainable crop production as a mulch or soil additive to suppress weeds

Bacterial Community Profiling of Tropical Freshwaters in Bangladesh

Seasonal and spatial variations in the bacterial communities of two tropical freshwater sources in Bangladesh, Lake Dhanmondi in central Dhaka, and a pond in the outskirts of Dhaka, were assessed and compared using PCR-DGGE and deep sequencing of 16S rRNA genes, as well as heterotrophic enrichments using water samples collected at nine different time points during 1 year. Temporal and spatial variations of common aquatic bacterial genera were observed, but no clear seasonal variations could be depicted. The major bacterial genera identified from these two sites were members of the Proteobacteria, Cyanobacteria, Actinobacteria, Bacteroidetes, Chlorobi, Chloroflexi, Verrucomicrobia, and Firmicutes. Among the proteobacterial groups, members of the α-, β-, and γ- Proteobacteria predominated. γ- Proteobacteria belonging to the Escherichia coli/Shigella group even the diarrheagenic pathotypes of E. coli e.g., EPEC and ETEC were detected in most samples throughout the year, with no apparent correlations with other microbial groups. The other pathotypes, EHEC, EAEC, and EIEC/Shigella spp. were also detected occasionally. This study represents the first thorough analysis of the microbial diversity of tropical freshwater systems in Bangladesh

Comprehensive evaluation of heavy metals in surface water of the upper Banar River, Bangladesh

The main focus of the research was to examine the dispersion of elements and evaluate the possible ecological impact of heavy metals in the water of the Upper Banar River. To achieve this, water samples were obtained from ten different locations along the river, and the concentrations of Cr, Ni, Cu, Cd, Pb, and As were analyzed using an atomic absorption spectrophotometer (AAS). Results exhibited that the abundance of Cr, Ni, Cu, Cd, Pb, and As in water varied from 1.10 to 3.20, 0.11 to 1.30, 1.30 to 13.50, 1.14 to 1.91, 0.39 to 0.75 and 1.44 to 2.56 µgL-1, respectively. Mean (±SD) concentrations of considered metals declined with the following downward direction: Cu (5.07±4.11) > As (1.94±1.15) > Cr (1.81±0.63) > Cd (1.42±0.23) Pb (0.55±0.12) > Ni (0.54±0.41), indicated that concentrations were reasonably assorted throughout the observed region. Moreover, the Upper Banar River water was contaminated with heavy metals, but the pollution level was not significant based on HPI analysis. Based on the computed HEI values, water quality is deemed low hazard and lower degrees of contamination. Overall, the river\u27s water was still in good condition and had low levels of contamination, as per PI and CD ratings. Upper Banar River water\u27s computed ERI ranged from 7.24 to 12.16, which showed a low-risk level. The study concluded that the Upper Banar River experienced some metallic pollution because of anthropogenic disturbances. Thus, responsible authorities should immediately implement appropriate management strategies and conduct routine water quality monitoring. Int. J. Agril. Res. Innov. Tech. 13(1): 110-122, June 202

The 2008 Cholera Epidemic in Zimbabwe: Experience of the icddr,b Team in the Field

During August 2008-June 2009, an estimated 95,531 suspected cases of cholera and 4,282 deaths due to cholera were reported during the 2008 cholera outbreak in Zimbabwe. Despite the efforts by local and international organizations supported by the Zimbabwean Ministry of Health and Child Welfare in the establishment of cholera treatment centres throughout the country, the case-fatality rate (CFR) was much higher than expected. Over two-thirds of the deaths occurred in areas without access to treatment facilities, with the highest CFRs (>5%) reported from Masvingo, Manicaland, Mashonaland West, Mashonaland East, Midland, and Matabeleland North provinces. Some factors attributing to this high CFR included inappropriate cholera case management with inadequate use of oral rehydration therapy, inappropriate use of antibiotics, and a shortage of experienced healthcare professionals. The breakdown of both potable water and sanitation systems and the widespread contamination of available drinking-water sources were also considered responsible for the rapid and widespread distribution of the epidemic throughout the country. Training of healthcare professionals on appropriate cholera case management and implementation of recommended strategies to reduce the environmental contamination of drinking-water sources could have contributed to the progressive reduction in number of cases and deaths as observed at the end of February 2009

Protection against shigellosis caused by Shigella dysenteriae serotype 4 in guinea pigs using Escherichia albertii DM104 as a live vaccine candidate strain

Recently, we reported the induction of protective immunity by environmental Escherichia albertii strain DM104 against Shigella dysenteriae in guinea pig model. In this study, we assessed three different immunization routes, such as intranasal, oral, and intrarectal routes, and revealed differences in immune responses by measuring both the serum IgG and mucosal IgA antibody titers. Protective efficacy of different routes of immunization was also determined by challenging immunized guinea pigs against live S. dysenteriae. It was found that intranasal immunization showed promising results in terms of antibody response and protective efficacy. All these results reconfirm our previous findings and additionally point out that the intranasal immunization of the environmental E. albertii strain DM104 in guinea pig model can be a better live vaccine candidate against shigellosis

A comparison of traditional diarrhoea measurement methods with microbiological and biochemical indicators : a cross-sectional observational study in the Cox's Bazar displaced persons camp

Background Water, Sanitation, and Hygiene (WASH) systems aim to reduce the spread of enteric pathogens, particularly amongst children under five years old. The most common primary outcome of WASH trials is carer-reported diarrhoea. We evaluate different diarrhoea survey instruments as proxy markers of enteric pathogen presence in stool. Methods We recruited 800 community-based participants from the Cox's Bazar Displaced Person's Camp in Bangladesh, split evenly between the rainy (July/August 2020) and dry (November/December 2020) periods. Participants were randomized evenly into either a standard survey asking carers if their child under five years old has had diarrhoea in the past fortnight, or a pictorial survey asking carers to pick from a pictorial chart which stools their child under five years old has had in the past fortnight. We collected stools from a random sub-sample of 120. Stools were examined visually, and tested for proteins associated with enteric infection and 16 enteric pathogens. We calculated sensitivities and specificities for each survey type, visual examination, and proteins with respect to enteric pathogen presence. Findings The sensitivity of the standard survey for enteric pathogen presence was 0.49[95%CI:0.32,0.66] and the specificity was 0.65[0.41,0.85]. Similar sensitivities and specificities were observed for pictorial survey, visual inspection, and proteins. Interpretation While diarrhoea is an important sign in clinical practice it appears that it is a poor proxy for enteric pathogen presence in stool in epidemiological surveys. When enteric infection is of interest, this should be measured directly