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Biomedical subjects

N Biswas

Publications and source records attributed to N Biswas.

At least 55 records · Page 3Linked to original sources
PubMed1994

Inactivation of horseradish peroxidase by phenol and hydrogen peroxide: a kinetic investigation.

Inactivation of horseradish peroxidase (HRP) was examined in the presence of hydrogen peroxide alone and in the presence of hydrogen peroxide plus phenol. HRP is inactivated upon exposure to hydrogen peroxide (H2O2) by the combination of two possible pathways, dependent upon hydrogen peroxide concentration. At low H2O2 concentrations (below 1.0 mM in the absence of phenol), inactivation is predominantly reversible, resulting from the formation and accumulation of catalytically inert intermediate compound III. As H2O2 concentrations increase, an irreversible mechanism-based inactivation process becomes predominant. The overall inactivation comprised of both processes exhibits a second-order inactivation rate constant (kapp) of 0.023 +/- 0.005 M-1 s-1 at pH 7.4 and 25 degrees C. In the presence of both hydrogen peroxide fixed at 0.5 mM and phenol, HRP was inactivated in an irreversible, time- and phenol concentration-dependent process, also mechanism-based, with a kapp of 0.019 +/- 0.004 M-1 s-1.

Horseradish Peroxidase↗
PubMed1994

Enzymatic removal of selected aromatic contaminants from wastewater by a fungal peroxidase from Coprinus macrorhizus in batch reactors.

The use of enzymes such as horseradish peroxidase (HRP) for degrading or removing toxic organics from synthetic wastewater has been demonstrated previously. Potential alternatives to HRP are other peroxidases, various ligninases, haloperoxidases and laccases. Results of this study indicate that a fungal peroxidase from Coprinus macrorhizus (CMP) has the capability to catalyze the same reactions as HRP. Similarly, in batch reactors the trend and removal efficiency of aromatic compounds by CMP from synthetic wastewater depend on the nature of the compound.

Biotechnology↗
PubMed1991

Aplastic anemia associated with antithyroid drugs.

Prognosis in aplastic anemia is usually linked to the degree of hypoplasia in the bone marrow and pancytopenia in the blood. The authors were, therefore, intrigued when a patient with methimazole-associated aplastic anemia who satisfied criteria for severe disease recovered rapidly and completely once her drug was withdrawn. Review of the English language literature revealed ten fully documented cases of aplastic anemia associated with use of the antithyroid drugs methimazole, carbimazole, and propylthiouracil. Analysis of the ten and of an eleventh case presented here indicated that the disorder is typically characterized by severe pancytopenia and profound marrow hypoplasia, yet surprisingly good prognosis, ie, minimum survival of more than 70% with partial or complete recovery from symptoms and cytopenias in survivors within 2-5 weeks. The only deaths, both in the 1950s, were from brain hemorrhage in patients who were not transfused with platelets. The discrepancy between the clinical and laboratory severity of antithyroid drug-associated aplasia, on the one hand, and its relatively good prognosis and short term course, on the other, should be kept in mind when considering these patients for bone marrow transplantation or for therapy with antithymocyte globulin.

Adult↗
PubMed1991

A clinical study of intubating conditions under vecuronium bromide.

The drug vecuronium bromide, a short acting, non-depolarising agent with little side-effects, has brought much promise in the field of muscle relaxants. Fifth healthy patients were induced with injection thiopentone sodium 4 mg/kg and vecuronium bromide, 0.1 mg/kg was given IV. The earliest time at which the largest percentage of patients could be intubated satisfactorily was noted. The intubating conditions were estimated by scoring method. The duration of clinical relaxation was decided from the time of IV injection of vecuronium bromide to the return of muscle power of the non-respiratory muscles requiring repeat dose of the drug. The ideal intubating condition was achieved at 120 seconds and the duration of clinical relaxation ranged from 11-15 minutes.

Adult↗
PubMed1985

Antitumour activity of some platinum compounds.

A group of cis-ethylenediammine platinum (II) complexes were synthesized and their activity against Sarcoma-180 ascites tumour cells in mouse was tested. One of the compounds, Pt(HOCH2CH2NHCH2CH2NH2)Cl2, showed significant antitumour activity having little toxicity to the host. Like the parent compound, cis-DDP, it binds to DNA, but transcription is not the primary process inhibited by these compounds. The drug-DNA complex, though less toxic, was not more effective than the free drug.

Animals↗
PubMed1981

Urinary excretion of alpha 2 mu-globulin and albumin by adult male rats following treatment with nephrotoxic agents.

Nephrotoxic agents such as puromycin aminonucleoside (PAN) and sodium maleate (MAL) have been used to induce experimental glomerular proteinuria and tubular disease, respectively. Current studies show that PAN caused a massive loss of albumin in the urine while not affecting the excretion of the smaller, sex-dependent alpha 2 mu-globulin. On the other hand, MAL which inhibits the reabsorption of proteins, increased the loss of both alpha 2 mu and albumin. Both nephrotoxic agents increased the excretion of albumin when administered to female rats. MAL-induced proteinuria was used as a direct measure of the renal load for alpha 2 mu and albumin. Renal loads and excretion of alpha 2 mu and albumin were measured in male rats maintained on 0, 20, and 50% casein diets. On the protein-free diet, the excretion of both alpha 2 mu and albumin was reduced (less than 1 mg daily); their renal loads were almost totally reabsorbed. On a 50% casein diet the reabsorption of alpha 2 mu was reduced from a normal of 60% to 10% of the renal load. Thus the high protein diet increased the excretion of alpha 2 mu while having little effect on the excretion of albumin. We suggest that dietary protein exerts two levels of control on the excretion of protein in the urine of the adult male rat. Protein-deficient diets stimulate the general reabsorption of proteins thereby minimizing the excretion of alpha 2 mu and albumin. High protein diets appear to reduce selectively the reabsorption of alpha 2 mu-globulin, thereby increasing its excretion in the urine.

Albumins↗