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Biomedical subjects

B K Das

Publications and source records attributed to B K Das.

At least 127 records · Page 7Linked to original sources
PubMed1992

Salting-out behaviour of the domains of ovomucoid.

The solubility of ovomucoid and of four fragments comprising domain I, I+II, and III of the protein in concentrated ammonium sulphate solution were studied at different pHs (25 degrees C) and at various temperatures (pH 7.0), and the salting-out parameters Ks and beta were determined for the five proteins. The aqueous solubilities of ovomucoid and the four fragments were highly dependent on temperature which causes structural alteration due to thermal unfolding of the proteins. The values of KS and beta for domain III and domain II+III at different pHs were similar to those of other globular proteins whereas those of ovomucoid and domain I and domain I+II were atypical. They were explained in terms of the lack of structural stability and the presence of carbohydrate moieties in domains I and II.

Ammonium Sulfate↗
PubMed1992

Haematological and coagulation profile in acute falciparum malaria.

The haematological and coagulation profile of 30 cases of acute falciparum malaria were studied. Anaemia, mostly normocytic, normochromic, was observed in 86.7% of cases majority of whom had complications. Severe anaemia (HB < 6gm.) observed in 10% of cases was associated with 100% mortality. Leucocytosis and leucopenia were observed in 13.3% and 6.6% of cases respectively. 90% of cases had thrombocytopenia, the lowest count recorded being 26,000/- cmm. 16.7% of cases had evidence of intravascular coagulation but manifested as generalised bleeding in only one case. Bone marrow aspiration done in 10 cases revealed no abnormality, except for falciparum parasites observed in 2 cases.

Adult↗
PubMed1991

Unfolding-refolding behaviour of chicken egg white ovomucoid and its correlation with the three domain structure of the protein.

The urea and heat-induced unfolding-refolding behaviours of chicken egg white ovomucoid and its four fragments representing domains I, II + III, I + II and III were systematically investigated in 0.06 M sodium phosphate buffer (pH 7.0) by difference spectral measurements. The effect of temperature on ovomucoid and its fragments was also studied in 0.05 M sodium acetate buffer (pH 5.0) and in presence of 2 M urea at pH 7.0. Intrinsic viscosity data showed that ovomucoid and its different fragments did not lose any significant amount of their structure under mild acidic conditions (pH 4.6). Difference spectral results showed extensive disruption of the native structure by urea or temperature. Isothermal transitions showed single-step for domain I, domain I + II and domain III, and two-step having one stable intermediate, for ovomucoid and its fragment representing domain II + III. However, the presence of intermediate was not detected when the transitions were studied with temperature at pH 7.0. Strikingly, the single-step thermal transitions of ovomucoid and its fragment representing domain II + III, became two-step when measured either at pH 5.0 or in presence of 2 M urea at pH 7.0. Analysis of the equilibrium data on urea and heat denaturation showed that the second transition observed with ovomucoid or domain II + III represent the unfolding of domain III. The kinetic results of ovomucoid and its fragments indicate that the protein unfolds with three kinetic phases. A comparison of three rate constants for the unfolding of intact ovomucoid with that of its various fragments revealed that domain I, II and III of the protein correspond to the three kinetic phases having rate constants 0.456, 0.120 and 0.054 min-1, respectively. These data have led us to conclude: (i) the unusual stability of ovomucoid towards various denaturants, including temperature, is due to its domain III, (ii) initiation of the folding of the ovomucoid molecule starts from its NH2-terminal region which probably provides the nucleation site for the formation of the subsequent structure and (iii) domains I and II have greater mutual recognition between them as compared to the recognition either of them have with domain III.

Animals↗
PubMed1991

Human cerebral malaria: characterization of malarial antibodies in cerebrospinal fluid.

Anti-malarial antibodies were quantified in cerebrospinal fluid (CSF) of 17 cases of cerebral malaria, 16 presumptive cases (no demonstrable parasitaemia in peripheral blood but responding to i.v. quinine therapy) of cerebral malaria, and 15 controls. A schizont-enriched Plasmodium knowlesi antigen was used in an ELISA. Anti-malarial antibodies of IgA and IgM isotypes were not detectable in most of the CSF samples analysed, although serum antibody titres were high. However, 88% of CSF from cerebral malaria and 56% of presumptive cerebral malaria cases had significant levels of IgG anti-malarial antibodies in comparison to control CSF. The antibody levels did not correlate with the severity of coma but correlated well with the duration of coma. The CSF malarial antibody titres were independent of degree of parasitaemia. The possible role of CSF anti-malarial antibodies in cerebral malaria in the light of recent demonstrations of intrathecal synthesis of immunoglobulins and deposition of immune complex in cerebral tissues is discussed.

Animals↗
PubMed1991

Lipid peroxidation in acute falciparum malaria.

Lipid peroxidation was assessed by measuring malondialdehyde (MDA) in 30 patients with falciparum malaria and 20 controls (10 healthy adults and 10 patients of vivax malaria). Mean serum MDA was 0.96 +/- 0.38 nmol/ml, 1.1 +/- 0.17 nmol/ml and 2.9 +/- 1.1 nmol/ml in healthy controls, disease controls and falciparum malaria patients, respectively. Levels were significantly high (P less than 0.001) in patients with falciparum malaria. Higher values were associated with more number of complications and deaths.

Acute Disease↗
PubMed1990

Ovomucoid domains: preparation and physico-chemical characterization.

Four fragments of ovomucoid representing its individual domains and their different combinations were prepared by peptic and cyanogen bromide cleavages of the protein. The fragments corresponding to domains I + II, II + III, I and III of the parent ovomucoid molecule, were found to be homogeneous by gel filtration and polyacrylamide gel electrophoresis in presence and absence of SDS. Various physico-chemical properties of these proteins, such as molecular weight, NH2- and COOH-terminal amino acid residues, sugar content, isoionic pH, specific extinction coefficient, fluorescence emission spectra, intrinsic viscosity, frictional coefficient, Stokes radius, diffusion coefficient and geometrical mean radius were determined. Analysis of the results on trypsin inhibitory activity of ovomucoid and its different fragments suggested that only domain II is involved in the antitryptic activity of the inhibitor. Optical characteristics of these fragments indicate that they are devoid of tryptophan residues. The hydrodynamic properties suggest that intact ovomucoid and two of its fragments (domain I + II and domain II + III) are significantly different from those of typical globular proteins and are asymmetric in nature. However, the shape of the two remaining fragments representing domains I and III of the intact protein appeared to be compact and globular. Furthermore, domain II of ovomucoid has been suggested to primarily contribute towards the apparent asymmetry in the intact protein.

Animals↗
PubMed1990

Immunopathological changes in kidney in Plasmodium falciparum malaria.

Fifteen (34.8%) of 43 patients of falciparum malaria screened for urinary abnormalities showed significant proteinuria (greater than 150 mg/24 h), haematuria (greater than 1/HPF) and casts, with or without azotaemia. Light microscopic examination of renal biopsy tissue from 12 patients revealed mesangial and endothelial proliferative change in 8, and acute tubular necrosis in one patient. Immunofluorescence showed IgM alone, or IgG and IgM along with C3, in 7 patients within the mesangium or along the capillary walls. Repeat kidney biopsy after 6 wk in 5 patients revealed no residual pathology indicating the reversible nature of the lesions.

Animals↗
PubMed1990

Double blind clinical trial on centperazine & DEC in bancroftian filariasis.

Centperazine, an analogue of DEC, was subjected to a double blind controlled trial, to evaluate its efficacy as a newer antifilarial agent. Centperazine (300 mg/day) along with equivalent quantities of DEC and placebo were administered to different types of filariasis patients. DEC was found to be significantly effective in reducing peripheral microfilaraemia, in different weeks and months of follow-up, except at the end of 6th month, as compared to Centperazine. There was no significant difference between the placebo and Centperazine treated patients, in this respect, revealing that the drugs had no efficacy in eliminating peripheral microfilaraemia. Recurrence of acute attack within 6 months was nearly equal with both Centperazine and DEC, being 28.2 and 24 per cent respectively, whereas in the placebo group the recurrence rate was 48.9 per cent. Centperazine treated patients showed significantly less side effects (8.9%), as compared to DEC treated patients (34%). Giddiness, nausea and vomiting were the common adverse effects observed.

Adolescent↗
PubMed1990

Physical microenvironment of platelet membrane in acute myocardial infarction.

Patients with acute myocardial infarction have more reactive platelets than those from normal population. These pathological platelets had more viscous plasma membrane, as inferred from fluorescence polarisation studies, and a lower fusion activation energy (delta E) of the membrane, reflecting a higher degree of order within lipid-lipid interactions.

Blood Platelets↗
PubMed1989

Immune status of volunteers one year after administration of Japanese encephalitis vaccine produced in India.

The immune status of 40 volunteers who received the full course of Japanese encephalitis (JE) vaccine a year earlier and 15 individuals who had received only a booster dose at the same time, was studied by estimating the level of persistence of protective antibody in the sera. All the sera showed persistence of 100 per cent seroconversion rate. Individuals who had the full course of vaccination still had high levels of antibody (mean 2.8 Iog10); however there was a fall of 0.8 Iog10 from the post-booster level. Volunteers who had received only a booster dose, also showed persistence of high level of protective antibody (mean 2.4 Iog10), a drop of 0.9 Iog10 from the post-booster level. Neutralizing (N) antibody estimated using Dibrugarh (7812474) strain of JE virus also demonstrated persistence of high level of protective antibody against this virus (mean 2.4 Iog10). Persistence of high level of protective antibody against homologus and heterologus (Dibrugarh) virus strains and absence of vaccine related side-effects even one year after administration of JE vaccine produced in India, demonstrates the immunizing potency and safety of this new vaccine.

Adolescent↗
PubMed1989

Hemostatic changes in neonates with anoxia and sepsis.

Hemostatic profile (prothrombin time (PT), thrombin time (TT), kaolin cephalin clotting time (KCCT), plasma fibrinogen, serum fibrin/fibrinogen degradation products (FDP) and platelet counts) was examined in 153 neonates with birth anoxia and 86 with sepsis. Remarkable hemostatic alterations occurred in neonates with severe anoxia and sepsis, while those with moderate anoxia exhibited minimal or no change. Vitamin K administration to anoxic babies showed no improvement in the hemostatic profile after 48-72 hours. The hemostatic alterations were presumably due to incipient disseminated intravascular coagulation (DIC). In spite of the marked coagulation changes, only 3 neonates with sepsis and none of the anoxic newborns presented with clinical bleeding indicating a well balanced hemostatic mechanism.

Bacterial Infections↗