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Biomedical subjects

S Chowdhury

Publications and source records attributed to S Chowdhury.

At least 19 recordsLinked to original sources
PubMed1992

Osmotic stress and the yeast cytoskeleton: phenotype-specific suppression of an actin mutation.

In the yeast Saccharomyces cerevisiae, actin filaments function to direct cell growth to the emerging bud. Yeast has a single essential actin gene, ACT1. Diploid cells containing a single copy of ACT1 are osmosensitive (Osms), i.e., they fail to grow in high osmolarity media (D. Shortle, unpublished observations cited by Novick, P., and D. Botstein. 1985. Cell. 40:415-426). This phenotype suggests that an underlying physiological process involving actin is osmosensitive. Here, we demonstrate that this physiological process is a rapid and reversible change in actin filament organization in cells exposed to osmotic stress. Filamentous actin was stained using rhodamine phalloidin. Increasing external osmolarity caused a rapid loss of actin filament cables, followed by a slower redistribution of cortical actin filament patches. In the recovery phase, cables and patches were restored to their original levels and locations. Strains containing an act1-1 mutation are both Osms and temperature-sensitive (Ts) (Novick and Botstein, 1985). To identify genes whose products functionally interact with actin in cellular responses to osmotic stress, we have isolated extragenic suppressors which revert only the Osms but not the Ts phenotype of an act1-1 mutant. These suppressors identify three genes, RAH1-RAH3. Morphological and genetic properties of a dominant suppressor mutation suggest that the product of the wild-type allele, RAH3+, is an actin-binding protein that interacts with actin to allow reassembly of the cytoskeleton following osmotic stress.

Actins↗
PubMed1992

Towards an essential data set: applicability in the domain of maternal health services.

There is a need for consensus on the quantity of data that must be available in a computer-based information system of a health care organization. In this paper we take up the issue of defining the data content of an information system and introduce the concept of Essential Data Sets with an explicit methodology which was applied to define a data set for the Maternal Health Services program. A key step in the method was a recognized technique used in systems development process called data modelling, in this case infological modelling, by an interdisciplinary group. A preliminary set of 86 data elements was identified and it provided the foundation for development of an application software for discussion and a real-world testing framework. The acceptability of the data set was tested in a laboratory perspective by retrospective data entry from records of 94 pregnant women registered at a maternal health care center in Sweden. Data from a total of 1,318 prenatal visits, an outcome visit, and a postnatal visit for each woman was entered into a computer using the software, with no loss of information. Thus, in a short-term perspective the acceptability of the data set was demonstrated. The software has since been implemented for pilot prospective studies at sites in India and Sweden. The use of a common data protocol is an essential foundation for patient outcome research, especially as the trend of health care management has changed from a "process of care" orientation to an "outcome of care" orientation.

Electronic Data Processing↗
PubMed1991

Methods for knowledge extraction from a clinical database on liver diseases.

We performed exploratory data analysis (EDA) to examine the hidden structure in liver disease data. The purpose was to demonstrate the potential of statistical techniques for extracting knowledge from an active HIS (hospital information system) database with decision support. The goal is to give strong support to the creation of new rules or "tuning" of old rules in the knowledge base. This would facilitate utilization of large patient databases, now commonly available, to help build/update decision support systems for improved patient care. Several statistical techniques were investigated. Stepwise discriminant analysis was found to be a good method in discriminating among different disease classes. Results showed that classification strength of a few (3) variables was similar to all the available (19) variables. Other important issues in the work are treatment of missing values as well as atypical values in medical databases. In estimating missing values we utilized both statistical methods and artificial intelligence approaches. Both these approaches were promising in the estimation of missing values. The study showed that several statistical approaches are possible for knowledge extraction from clinical data collected retrospectively.

Artificial Intelligence↗
PubMed1991

Chemical modification studies of Artocarpus lakoocha lectin artocarpin.

The effect of chemical modification on an anti T-like lectin, artocarpin isolated from Artocarpus lakoocha seeds was investigated in order to identify the type of amino acids involved in its agglutinating activity. Modification of carboxyl groups, arginine and lysine residues, did not affect the lectin activity. However, modification of tryptophan, tyrosine and histidine residues led to a complete loss of its activity, indicating the involvement of these amino acids in the saccharide-binding ability. A protection was observed in the presence of inhibitory sugar. A marked decrease in the fluorescence emission was found when the tryptophan residues of lectin were modified. The circular dichroism spectra showed the presence of an identical pattern of conformation in the native and modified lectin, indicating that the loss in activity was due to modification only. The effect of pronase on artocarpin showed loss of activity whereas papain and trypsin had no effect. The specific activity of artocarpin remained unaltered on treatment with glycosidases but remarkable increase in the activity (of the same) was observed with xylanase treatment. Immunodiffusion studies with chemically modified lectin showed no gross structural changes, indicating that the group specific modifying agents did not alter the antigenic sites of the modified lectin.

Amino Acids↗
PubMed1991

ABO blood groups and the risk of diarrhea due to enterotoxigenic Escherichia coli.

To determine whether blood group O persons are at higher risk for enterotoxigenic Escherichia coli (ETEC) diarrhea, a case-control study was done for 17 months among rural Bangladeshis who were under systematic surveillance for diarrhea. Cases were children less than 3 years old who presented between 1 January 1985 and 1 June 1986 for care of heat labile (LT) or heat stabile toxin-producing ETEC diarrhea. Controls were of similar ages and were randomly selected from three community-based serosurveys between July 1985 and May 1986. No association between blood group O and ETEC diarrhea was found for the 510 cases and 641 controls, nor was an association evident for cases of each toxin phenotype. Further refinement of the case definition to include only patients with LT-ETEC diarrhea, without enteric copathogens, also failed to reveal a substantial association with blood group O. These data suggest that a strong association with ABO groups, analogous to that for cholera, does not exist for ETEC diarrhea.

ABO Blood-Group System↗
PubMed1991

Positive response to sodium antimony gluconate administration in visceral leishmaniasis seropositive patients.

In a prospective study conducted in Mymensingh district of Bangladesh, 1, 273 patients were assessed for the presence of visceral leishmaniasis (VL). Sodium antimony gluconate (SAG) was successfully administered to 715 patients with parasitologically confirmed infection. In the remaining 558, although there was clinical indication of VL, Leishmania donovani parasites could not be demonstrated. Administration of SAG in this group was on the grounds of the prevailing symptoms, exclusion of malaria and a positive direct agglutination test (DAT). Significant improvements in the clinical and hematological parameters were observed in 547 (98%) of the unconfirmed VL cases. On the basis of the parasitological findings or positive response to specific anti-Leishmania chemotherapy, the sensitivity and specificity of the DAT were 99.6% and 97.7% respectively. The results supported the reliability of DAT for diagnosis of VL at levels below that of parasitological detection.

Agglutination Tests↗
PubMed1991

Integrated approach for designing medical decision support systems with knowledge extracted from clinical databases by statistical methods.

In clinical research data is often studied by a particular method without previous analysis of quality or semantic contents which could link clinical database and data analytical (e.g. statistical) procedures. In order to avoid bias caused by this situation, we propose that the analysis of medical data should be divided into two main steps. In the first one we concentrate on conducting the quality, semantic and structure analyses. In the second step our aim is to build an appropriate dictionary of data analysis methods for further knowledge extraction. Methods like robust statistical techniques, procedures for mixed continuous and discrete data, fuzzy linguistic approach, machine learning and neural networks can be included. The results may be evaluated both using test samples and applying other relevant data-analytical techniques to the particular problem under the study.

Artificial Intelligence↗
PubMed1990

Extracting knowledge from a large primary health care database using a knowledge-based statistical approach.

Clinical databases from automated medical records represent a growing resource for deriving new medical knowledge. In this study a large primary health care database was explored with respect to the association between hypertension and diabetes. Data collection was made with a query language, and data analysis performed with an interactive knowledge-based statistical tool, MAXITAB, employing a multivariate tabular analysis technique. In the study population of 6660 patients the prevalence of diabetes was almost three times higher for hypertensive patients than for those with no hypertension. Conversely, the prevalence of hypertension was 2.6 times higher for diabetic patients than for those with no diabetes. The results support the assumption of a relationship between hypertension and diabetes, although the question of causality between the two diagnoses remains unsolved. Knowledge-based statistical tools of this kind may be feasible for exploring large clinical databases and may result in new medical hypotheses, worthy of further investigation.

Aged↗
PubMed1990

In vivo viability and functional integrity of filtered platelets.

The in vivo viability and functional integrity of filtered platelets were compared with those of nonfiltered platelets in a controlled study. On two occasions, after template bleeding time, 14 healthy volunteers underwent plateletpheresis and received 600 mg of aspirin. Autologous 111In-labeled platelets were transfused without further manipulation (control) on one occasion and after filtration on a second occasion. The filter was primed and flushed with a buffered 12.6-percent solution of ACD-A in 0.9-percent normal saline (pH 6.5). After transfusion, the bleeding time was measured at 1, 4, and 24 hours and platelet survival at 10 minutes; 1, 4, and 24 hours; and daily for 6 days. The decrease in the bleeding time was not significantly different from that after transfusion of nonfiltered platelets (p greater than 0.2). Filtering of platelets did not affect 1-hour in vivo recovery (filtered, 69.5%; nonfiltered, 66%: p = 0.56) or the platelet survival (filtered platelet t1/2 = 83.0 hours, nonfiltered platelet t1/2 = 82.9 hours: p = 0.96). It can be concluded that filtration does not adversely affect in vivo recovery, survival, or functional integrity of platelets.

Bleeding Time↗
PubMed1990

Breast feeding and the risk of severe cholera in rural Bangladeshi children.

The association between breast feeding and the risk of severe cholera was examined in a case-control study of rural Bangladeshi children under 36 months of age who were studied in 1985-1986 during a field trial of killed oral cholera vaccines. A total of 116 cases who were treated for severe cholera were compared with 464 age-matched community controls without severe cholera. Overall, the odds ratio relating breast feeding to severe cholera (0.30, p less than 0.0001) reflected a 70% reduction in the risk of severe cholera among breast-fed children. The estimated reduction of risk declined with age, but was clearly evident in children up to 30 months of age. Although the association between breast feeding and a reduced risk of severe cholera was not significantly greater in children of mothers who had received cholera vaccine than in children whose mothers had received placebo during the trial, maternal vaccination per se was suggestively associated with a reduced risk of severe cholera in their nonvaccinated children (odds ratio = 0.53, p = 0.05). These results indicate that breast feeding was associated with a substantial reduction of the risk of severe cholera and raise the possibility that vaccination of mothers may provide protection to their young children in endemic settings.

Bangladesh↗
PubMed1990

Buprenorphine abuse: report from India.

Buprenorphine has been stated a drug of low abuse potential and often used therapeutically in the management of opiate addicts. An analysis of 2 1/2 years' experience of opiate addiction cases at a de-addition clinic revealed its increasing rate of abuse, especially as a substitute for heroin.

Buprenorphine↗
PubMed1989

A knowledge-based system for data analysis and interpretation.

Traditionally, statistical packages are employed to derive or infer facts about a Universe of Discourse through data analysis and interpretation. It is analysis that serves to transform data into information. Statistical packages provide the users with relatively easy-to-use and powerful mechanics of data analysis, but up to now they do not provide much help with the design and strategies of the analysis. As such, there is a risk of misuse of these packages by statistically inexperienced users. We propose the use of knowledge-based interfaces to support this category of users in statistical evaluations. This paper discusses our experiences from the implementation of a knowledge-based system called MAXITAB. It provides guidance in the processes of data analysis and interpretation and has been programmed as an interface to the statistical package MINITAB.

Data Interpretation, Statistical↗
PubMed1988

Discontinuation of breast-feeding during episodes of diarrhoea in rural Bangladeshi children.

Discontinuation of breast-feeding during an episode of childhood diarrhoea is widely regarded as a common, high-risk practice in the developing world. We studied cessation of breast-feeding in a rural Bangladeshi population under comprehensive surveillance for medically treated diarrhoeal episodes. Among 2129 episodes in children aged under 36 months and breast-fed before the onset of diarrhoea, there were only 33 (2%) in whom breast-feeding had stopped before presentation for care. Children in whom breast-feeding had stopped (cases) differed little from those in whom it had not (controls) in respect to exclusive vs partial breast-feeding, age, gender, or several maternal characteristics (maternal age, education, and recent maternal diarrhoeal illness). In contrast, cases were more likely to have presented with clinically severe illness or to have died within 30 d of presentation (odds ratio = 2.20, P less than 0.05). We conclude that discontinuation of breast-feeding during diarrhoea is an infrequent phenomenon in this population. However, the association of cessation of breast-feeding with severe clinical outcomes may be of considerable importance, particularly in countries where discontinuation of breast-feeding is more common.

Bangladesh↗
PubMed1988

The search for an 111In labeled agent for the solid component of gastric emptying.

111In-labeled solid meal was prepared by chelation of 111In with Chelex resin bead. The effect of grinding of normal Chelex bead on 111In chelation and retention in solid meal was evaluated in an in vitro system. The Chelex resin beads were ground in a mortar-pestle to form ground Chelex resin beads. Fine particles were removed by resuspension in distilled water and centrifugation (1000 g). One hundred to 150 microCi of 111In chloride was diluted with 0.1 N HCl and mixed with 1 g of Chelex resin beads. Unbound 111In was removed by centrifugation (1000 g). The 111In-labeled Chelex resin beads were mixed with fresh egg and 111In-labeled solid meal was prepared by heating until solid. The meals were digested with HCl-pepsin (1.2 mg/mL of pepsin in 0.1 N HCl) for 4 h in a stirrer-bath (37 degrees C). Aliquots were collected at intervals for determination of 111In loss from 111In-labeled solid meal. These results suggest that 111In Chelex resin beads were retained in solid meals at a higher level than normal Chelex resin beads and other 111In-tracers.

Digestion↗
PubMed1988

Labeled polymorphonuclear leukocytes: a comparison of methodology.

Polymorphonuclear neutrophilic granulocytes were separated from anti-coagulated whole blood using three techniques. The methods employed included volex sedimentation (VS), volex sedimentation with hypotonic lysis (VSHL), and Ficoll-Hypaque gradient separation (FH). The cells were labeled with 111In-oxine and 111In-tropolone. Studies were done with both blood from normal human volunteers and with canine blood. From the cell counts and differential, the harvested granulocytes, platelets, and red blood cells per milliliter of whole blood were calculated. Using the granulocyte chemotactic response to E. coli in agarose plates, the ratio of chemotactic migration to random migration (c.m./r.m.) was determined. Survival time for 111In labeled granulocytes were also determined in a canine model. The studies demonstrated that all procedures yielded 100% viability by the Trypan blue exclusion test. Chemotactic migration and leukocyte survival times were similar amongst all techniques. With the VSHL technique, there were significantly fewer red blood cells and platelets in the final preparation approaching the results of FH separation. The results suggest that for a relatively pure granulocyte preparation VSHL is an acceptable alternative to FH.

Animals↗