Search PubMed⌕ Search

Biomedical subjects

D Biswas

Publications and source records attributed to D Biswas.

70 records · Page 4Linked to original sources
PubMed1991

Expression of virulence and antibiotic resistance in an Escherichia coli transconjugant carrying a large plasmid pCAT120 of Shigella dysenteriae type I and its spontaneous fragmentations.

The role of a 120-kb plasmid in relation to virulence and drug resistance factor in Shigella dysenteriae was studied. For characterization of plasmids, the mating system is a useful and efficient means of transferring both large and small plasmids to a new host. The conjugative transfer of a 120-kb (pCAT120) ampicillin-resistant plasmid of S. dysenteriae to E. coli K-12 was not successful. Introduction of an E. coli fertility factor plasmid F, did not help to mobilize the plasmid. Low transfer frequencies of antibiotic markers to E. coli were achieved by treatment of the donor S. dysenteriae with N-methyl-N'-nitro-N-nitrosoguanidine. The transconjugants showed resistance to ampicillin, chloramphenicol, tetracycline and cadmium. A transconjugant carrying the 120-kb plasmid of S. dysenteriae produced keratoconjunctivitis in guinea pigs. Repeated subculture of Clmr transconjugant (pCAT120) on tryptic soya agar plates became Clms and showed four distinct DNA bands ranging from 3 to 10 kb in size on agarose gel electrophoresis. Utilization of organic acids, metal resistance (Cd), dye-binding properties (Crb+, Ebr+) and drug resistance (Amp, Tet) were identified on 10, 7, 4 and 3-kb plasmid DNA fragment of pCAT120 respectively. Crb+ 4-kb DNA fragment of pCAT120 was isolated, purified and transferred to an avirulent E. coli K12 by transformation. However, transformant (pET4) showed poor growth on solid media and its growth in liquid culture was only possible after supplementation of the unknown low-molar-mass thermolabile factor(s) secreted by the recipient strain.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacterial Outer Membrane Proteins↗
PubMed1991

Role of a large plasmid of Salmonella typhi encoding multiple drug resistance.

Twenty isolates of Salmonella typhi from cases of typhoid during the 1989-1990 epidemic in Calcutta were examined. Most isolates (84% of all isolates in the epidemic) were resistant to chloramphenicol, ampicillin, tetracycline and streptomycin but were sensitive to nalidixic acid and ciprofloxacin. Plasmids of 120 kb and 14 kb were identified amongst the multi-drug resistant isolates of S. typhi. However, there was no plasmid in the antibiotic-sensitive isolates. The 120-kb plasmid was transferable and transconjugants were resistant to chloramphenicol, ampicillin, tetracycline and streptomycin. Restriction endonuclease analysis patterns after EcoRI digestion of the 120-kb antibiotic-resistance plasmids from the S. typhi isolates and transconjugants were similar.

Chloramphenicol Resistance↗
PubMed1989

Annual transmission potential of bancroftian filariasis in an urban and a rural area of West Bengal, India.

The annual transmission potential of Wuchereria bancrofti was calculated from the number of infective larvae found in the number of Culex quinquefasciatus expected to bite an individual exposed 24 hr a day for a year in Calcutta and in a rural (Memari) area. In Calcutta, an average of 151 mosquitoes/night/person were collected; it was calculated that 55,028 mosquitoes could bite a person per year, including an average of 177 infective mosquitoes containing 319 infective larvae of W. bancrofti. At Memari, an average of 284 mosquitoes/night/person were collected; here with the resulting calculation was that 103,718 mosquitoes could bite a person per year, including an average of 137 infective mosquitoes containing 223 infective larvae. The annual transmission potential was higher in the urban area than that in the rural area. Annual transmission potential is useful knowledge in the epidemiological assessment of transmission dynamics for the formulation of control strategies.

Animals↗
PubMed1988

A newly discovered habitat of Anopheles stephensi in present-day Calcutta with evidence of natural malarial infection.

In Calcutta adult Anopheles stephensi mosquitoes were captured in significantly greater numbers from temporary human shelters than from their conventional resting places, such as brick built indoor rooms and cattlesheds, pointing out a change of behaviour in seeking their resting places which may have occurred due to excitorepelletory action of insecticides used indoors in bygone days.

Animals↗
PubMed1983

Three-layered Couette flow of polar fluid with non-zero particle spin boundary condition at the interfaces with applications to blood flow.

In this paper, Couette flow of blood is modelled as a three-layered flow. The model basically consists of a core (red-cell suspension) and plasma (a Newtonian fluid) in the top (near the moving plate) and bottom (near the stationary plate) layers. Flow is assumed to be steady and laminar and fluids are incompressible. A spin boundary condition at the interfaces is used by introducing two parameters. Analytic expressions for velocity, total angular velocity and effective viscosity have been obtained and their variations with spin parameters S and s, layer thickness, coupling number N and characteristic length ratio L are computed and shown graphically. One of the important observations of the analysis is the permissible values of the coupling number N is between 0 and 1/square root2 (in the existing literature, the range of N is 0 to 1). The present model includes Couette flow of one and three-layered Newtonian fluids and one-layered polar fluid models as its special cases. Applications of the proposed model to blood flow have been briefly discussed.

Blood Flow Velocity↗
PubMedDate not supplied

Hypertension and its risk factors in tea garden workers of Assam.

BACKGROUND: Hypertension is emerging as a major public health problem in India. The diversity and heterogeneity of distribution of the population makes it difficult to arrive at the precise prevalence. In Assam, reports from hospitals in tea gardens reveal a high prevalence of hypertension among workers in tea gardens. However, no systematic study has been carried out in this population. METHODS: We selected, by systematic sampling, 1015 individuals (512 men and 503 women) 30 years or more in age, who were interviewed and clinically examined for hypertension. Blood pressure of all the study participants was measured using a standardized technique. Crude and adjusted odds ratios were estimated by unconditional simple and multiple logistic regression analyses. Mantel-Haenszel chi2 analysis was also used to test for the association of potential risk factors with hypertension after controlling for co-variables in a stratified analysis. Risk factors considered for hypertension included age, gender, marital status, occupation, alcohol consumption (locally prepared), extra salt intake, smoking history, khaini (a form of tobacco quid containing a mixture of tobacco and lime) intake, body mass index and waist-hip ratio. RESULTS: The overall prevalence of hypertension was 60.8%. Increasing age, consumption of locally prepared alcohol, intake of extra salt in food and beverages and the habit of taking khaini were found to increase the risk of hypertension. Multivariate logistic regression models showed that the independent determinants of hypertension were age, gender, consumption of locally prepared alcohol and intake of extra salt. Gender-specific and age-stratified analyses showed the association of increased risk with intake of khaini in women only, while consumption of locally prepared alcohol was an important risk factor for hypertension in both men and women. CONCLUSION: The disease burden of hypertension among workers in tea gardens is large, despite the community not being obese. Interventions directed at these workers as well as studies to determine the reasons for the high prevalence of hypertension are required.

Adult↗
PubMedDate not supplied

Hypertension in the native rural population of Assam.

BACKGROUND: Recent studies have reported an increasing prevalence of hypertension in India. However, there are few epidemiological data with regard to the occurrence of hypertension in the native population of Assam. METHODS: Three thousand one hundred and eighty individuals (1441 men and 1739 women), > or =30 years of age and from 25 villages of 5 districts in Assam were selected by the stratified random sampling method. They were interviewed and their blood pressure measured along with other anthropometric variables. Hypertension was defined according to the Sixth Report of the Joint National Committee on prevention, detection, evaluation and treatment of high blood pressure (JNC-VI). RESULTS: The overall prevalence of hypertension was 33.3%. Among the patients with hypertension, 21.6% were aware of their illness. The determinants of hypertension were age, intake of extra salt in the diet, body mass index and waist-hip ratio (derived by multiple logistic regression analysis with backward elimination of non-significant factors). Multivariate analysis showed that females had a higher risk of hypertension than males. CONCLUSION: The prevalence of hypertension in the native population of Assam is high. Implementation of an effective awareness programme with lifestyle modifications is necessary to control the cardiovascular disease burden in this population.

Adult↗
PubMedDate not supplied

Study of the impact of epidemiological factors on intelligence of rural children of 3 to 6 years age group belonging to low socio-economic status.

There are many factors which affect intelligence as well as physical growth of children, although genetic factor plays a prime role but social, environmental and psychological factors influence significantly the physical growth and intelligence of the child and the same can be improved through intervention. Community based studies are therefore useful to understand effect of these factors for future planning. The present study was therefore undertaken in Burdwan district of West Bengal with the objectives of studying level of intelligence of children of 3 to 6 years age group and impact of the factors related to the level of intelligence of these children. 72 children of 3 to 6 years age group were studied, of which 2/3 were either normal or having Grade-I undernutrition and the rest were either Grade-II or Grade-III. A significant positive association was found between DST IQ score (Bharat Raj) and the nutritional grade. Non-formal education also was found to have significant bearing on the IQ level. No significant relationship was however found between DST IQ score and the religion indicating culture independence of the scoring system.

Child↗