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Biomedical subjects

B Das

Publications and source records attributed to B Das.

At least 91 records · Page 5Linked to original sources
PubMed1995

Non-Newtonian flow of blood in an arteriosclerotic blood vessel with rigid permeable walls.

The steady, laminar and fully developed flow of blood in an arteriosclerotic blood vessel with rigid permeable walls is investigated, taking into account the slip condition at the vessel walls. The constitutive equation of blood is represented by a Casson fluid model. The model is used to study the influence of the yield stress on blood flow through arteriosclerotic arteries. The variation of the flow resistance and wall shear stress, with permeability parameter, slip parameter and Casson number are obtained for different sizes of growth of the arteriosclerotic lesions. Comparison of the results is made with available results that consider the impervious wall and those that consider blood as a Newtonian fluid. It is found that permeability has a significant effect on the values of flow resistance and wall shear stress. Biological implications of the present model on different arterial diseases are discussed.

Aged↗
PubMed1995

A field study of worker productivity improvements.

This paper describes the results of an experimental industrial field study conducted to improve worker productivity through various interventions in a repetitive production task performed under ergonomic working conditions. Worker productivity was found to improve most as a result of participative standard-setting with feedback and monetary incentives. In general, standard-setting with feedback, with or without monetary incentives, improved worker productivity. The performance without interventions was far below the normal standard. It was concluded that under good working conditions, challenge and incentives may be advantageously applied to improve worker productivity in industry.

Journal Article↗
PubMed1995

Univentricular repair. Early and midterm results.

A total of 202 patients (62 with tricuspid atresia and 140 without tricuspid atresia) underwent univentricular repair at our unit from January 1990 to September 1994. Of these patients, 182 had nonfenestrated and 20 had fenestrated interatrial baffles. Early mortality was 15.9% (29/182) in the group with nonfenestrated baffles and 5% (1/20) in the group with fenestrated baffles. The follow-up period ranged from 2 to 58 months. Seven late deaths occurred, and five patients were lost to follow-up. Of 160 patients who have been evaluated in the outpatient department in the past 3 months, 142 (88.75%) required no cardiac medicines and were in functional class I. Risk factors analyzed for early mortality and significant effusion were age, preoperative diagnosis, type of Fontan modification, cardiopulmonary bypass time, aortic crossclamp time, pulmonary artery size, associated pulmonary arterioplasty, takedown of systemic-pulmonary artery shunt, and pulmonary artery debanding, along with the Fontan operation. Bypass time exceeding 120 minutes was associated with a higher early mortality (12/47 vs 18/155; p = 0.0187). Bypass time exceeding 120 minutes (p = 0.0456) and aortic crossclamp time exceeding 60 minutes (p = 0.0278) were associated with significant postoperative effusion. Other factors were not associated with any significantly increased risk for early mortality or postoperative effusions. Fenestration of the interatrial baffle appeared to decrease early mortality, although the numbers are too small to be statistically significant. The prevalence of effusions did not differ significantly between the group with fenestrated baffles and the group without fenestrated baffles.

Cardiopulmonary Bypass↗
PubMed1995

Computer-aided human modelling programs for workstation design.

In designing a workstation, computer-aided human modelling programs can be used advantageously to analyse human-fit to the workstation components. The analysis is performed within a three-dimensional computer graphics environment. To illustrate the current state of development, six representative programs were selected: CYBERMAN, COMBIMAN, CREW CHIEF, JACK, SAMMIE, and MANNEQUIN. The programs differ considerably in terms of system requirement, operating characteristics, applicability and the various ergonomic evaluation functions available in the human modelling programs. The comparative analysis of the programs will aid the user to select the appropriate program for a particular workstation design.

Anthropometry↗
PubMed1995

Studies on the genesis of Vibrio cholerae O139: identification of probable progenitor strains.

Four lines of evidence suggest that the recent outbreak strains of Vibrio cholerae O139 could have emerged from serogroup O1 strains typified by isolates M01 and M0477 described in this paper, which are neither truly classical nor truly E1 Tor in their biotype attributes. Firstly, like all O139 isolates, these O1 strains, isolated in Madras during and before the O139 outbreak, were resistant not only to polymyxin B but also to all biotype-specific choleraphages, i.e. classical phage phi 149 and E1 Tor phages e4 and e5. Secondly, the restriction fragment pattern (RFP) polymorphism displayed by these strains for the cholera toxin (ctx) gene, were identical with those produced by O139 isolates but were different from those of O1 type strains, namely V. cholerae 569B (classical) and V. cholerae MAK757 (E1 Tor). Thirdly, all the O139 isolates and the two O1 isolates carried an identical large number of copies of cholera toxin gene in their chromosomes. Finally, the outer-membrane protein profiles of strains M01 and M0477 were identical to those of O139 isolates but were different from those displayed by strains 569B and MAK757.

Bacterial Outer Membrane Proteins↗
PubMed1995

Pregnancy associated anemia and iron: a pilot study.

Iron deficiency occurs when the rate of loss of utilization exceeds its assimilation. Treatment is based on iron supplementation but due to side effects compliance to iron therapy is poor. A double blind comparative study was done using a novel time release preparation of ferrous sulphate (Code A) v.s. sustained release ferrous sulphate preparation (Code B) on 60 pregnant women in mid or late pregnancy with anaemia. The amount of ferrous sulphate in Code A was less than half of Code B. The patients were sequentially randomised as Code A or Code B recipient. The non compliance rate was 33%, and for both Code A & Code B. The mean improvement in hemoglobin after 4 weeks of therapy was 2.01 gm% for Code A and 2.3 gm% for Code B. Iron absorption as evidenced by improvement in S. Iron, TIBC and ferritin levels was better with Code A. The improvement in subjective symptoms of anaemia was better than average in Code B preparation. Code A group had comparatively more side effects both major and minor, this may have been the reason for a slightly higher drop out rate in this group. In conclusion the timed release preparation has a comparable haematological response and better absorption with significantly lower doses as compared to the sustained release preparation.

Adult↗
PubMed1994

Cloning and analysis of human cDNAs encoding a 140-kDa brain guanine nucleotide-exchange factor, Cdc25GEF, which regulates the function of Ras.

Ras proteins bound to GDP are biologically inactive while those bound to GTP are active. Ras-specific guanine nucleotide-exchange factors (GEFs) have been shown to activate Ras proteins. We used oligodeoxyribonucleotide primers with sequences similar to the cDNAs of rat and mouse cdc25 (encoding a Ras-GEF) to amplify, by the PCR, sequences with the potential to encode a 1275-amino-acid protein homologous to the rodent Cdc25GEF proteins. Northern blot analysis detected a brain-specific 5-kb transcript. We provide evidence for a novel alternately spliced transcript of cdc25 and show that these alternately spliced transcripts are differentially expressed in various regions of the adult nervous system. Antibodies raised against the C terminus of the protein recognize a 140-kDa protein in brain extracts of human, rat, guinea pig and cow; the 140-kDa protein is associated predominantly, if not exclusively, with a crude membrane fraction of brain. The C terminus of human Cdc25GEF can complement the loss of CDC25 function in Saccharomyces cerevisiae. A glutathione S-transferase fusion protein containing the C terminus of the cdc25 product can stimulate guanine nucleotide exchange on H-Ras in vitro. Further, the Cdc25-fusion protein binds tightly to the nucleotide-free form of H-Ras in vitro, and this binding is reversed by the addition of GTP.

Alternative Splicing↗
PubMed1994

A novel ligand in lymphocyte-mediated cytotoxicity: expression of the beta subunit of H+ transporting ATP synthase on the surface of tumor cell lines.

Extracellular adenosine triphosphate (eATP) has been suggested to play a role in lymphocyte-induced tumor destruction. We now provide evidence that a protein responsible for ATP synthesis in mitochondria may also play a physiologic role in major histocompatibility complex-independent, lymphocyte-mediated cytotoxicity. A 51.5-kD protein (p51.5) bearing structural and immunologic characteristics of the beta subunit of H+ transporting ATP synthase (E.C. 3.6.1.34, beta-H+ATPase, published molecular mass of 51.6 kD) was detected on the plasma membrane of three different human tumor cell lines studied. NH2-terminal amino acid sequence analysis of purified p51.5 from K562 tumor cells revealed 100% homology of 16 residues identified in the first 21 positions to the known sequence of human mitochondrial beta-H+ ATPase. Antibody directed against a 21-mer peptide in the ATP binding region of beta-H+ ATPase (anti-beta) reacted with only one band on Western blots of whole tumor extracts and tumor membrane extracts suggesting that the antiserum reacts with a single species of protein. Anti-beta reacted with the cell membranes of tumor cells as determined by fluorescence-activated flow cytometry and immunoprecipitated a 51.5-kD protein from surface-labeled neoplastic cells (but not human erythrocytes and lymphocytes). Purified p51.5 bound to human lymphocytes and inhibited natural killer (NK) cell-mediated cytotoxicity. Furthermore, anti-beta treatment of the K562 and A549 tumor cell lines inhibited NK (by > 95%) and interleukin 2-activated killer (LAK) cell (by 75%) cytotoxicity, respectively. Soluble p51.5 upon binding to lymphocytes retained its reactivity to anti-beta suggesting that the ATP binding domain and the lymphocyte-receptor binding domain reside in distinct regions of the ligand. These results suggest that beta-H+ ATPase or a nearly identical molecule is an important ligand in the effector phase (rather than the recognition phase) of a cytolytic pathway used by naive NK and LAK cells.

Amino Acid Sequence↗
PubMed1994

Refolding of denatured lactate dehydrogenase by Escherichia coli ribosomes.

Escherichia coli ribosomes were used to refold denatured lactate dehydrogenase from porcine muscle. This activity of ribosomes, unlike most of the chaperons, did not require the presence of ATP. The molar concentration of ribosomes required for this refolding was comparable with that of the enzyme. Restoration of the enzyme activity was demonstrated using assays for both the forward and backward reactions. Binding of the denatured enzyme to ribosomes and its refolding were fairly rapid processes as revealed by the time course of the reaction and inhibition of folding when the denatured enzyme was allowed to refold spontaneously for short times before the addition of ribosomes. This protein-folding activity was detected in 70 S ribosomes as well as its RNA, in 50 S particles and in 23 S rRNA. However, 30 S particles failed to refold the enzyme.

Escherichia coli↗
PubMed1994

Infection in haematological malignancies.

Fifty-six febrile episodes in 30 haematological malignancy cases were evaluated. Of these episodes 60.7% were in leukaemia cases. Clinical evaluation and investigation suggested infection in 42 episodes (75%) of fever and in rest 14 (25%) no identifiable cause could be found. Bacterial infection predominated with an incidence of 80.9% followed by fungal infection in 11.9% and parasitic infection in 7.1% of the febrile episodes. Gram-negative bacteria were more frequently isolated (22/34) than Gram-positive bacteria (12/34). Staph aureus was the commonest Gram-positive organism. Kl pneumoniae and Esch coli were the common Gram-negative pathogens. The commonest organisms were sensitive to cephalosporin and gentamicin. Incidence of fever due to infection was significantly higher (p < 0.001) in patients with absolute neutropenia, in whom the mortality rate was significantly higher (p < 0.001).

Bacterial Infections↗
PubMed1994

Refolding of denatured restriction endonucleases with ribosomal preparations from Methanosarcina barkeri.

Two restriction endonucleases, EcoRI and HindIII were denatured by guanidine HC1 or by storing at room temperature denatured by guanidine HC1 or by storing at room temperature (28 degrees C) for several days. The activity of these enzymes could be restored by incubating with ribosomal preparations from an archaebacterium Methanosarcina barkeri. These results hint at a possible role of ribosomal preparations in folding polypeptides and could be useful in working with restriction enzymes in experiments on genetic engineering and molecular biology.

Bacterial Proteins↗
PubMed1993

Three flavone glycosides from Gelonium multiflorum.

Two new flavone diglycosides along with 7,4'-O-dimethylscuttelarein 6-O-beta-D-glucopyranoside, a known glycoside, were isolated from the seeds of Gelonium multiflorum and their structures were elucidated as 7,4'-O-dimethylscuttelarein 6-O-alpha-L-rhamnopyranosyl(1-->2)-beta-D-glucopyranoside and 6-O-beta-D-xylopyranosyl(1-->2)-beta-D-glucopyranoside.

Carbohydrate Sequence↗
PubMed1993

Evaluation of an on-the-job operator training method.

An experimental investigation was conducted to determine if the operators trained by the comprehensive on-the-job operator training method can maintain the production output level on a continuous basis in a repetitive production task. The components of the training method included: Methods-Time-Measurement (MTM) analysis, operator instruction sheet, demonstration, practice session, feedback, and guidance. The operators were able to sustain the production quantity and quality output levels achieved at the end of the training period for the entire experimental work session. The use of the training method is recommended.

Analysis of Variance↗