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Biomedical subjects

M Banerjee

Publications and source records attributed to M Banerjee.

At least 109 records · Page 6Linked to original sources
PubMed1992

A visual method for rapid screening of xylose-fermenting ethanolic strains of Klebsiella pneumoniae.

A simple and rapid screening method for selecting hyper-ethanolic strains of Klebsiella pneumoniae is described. The method involves a novel biological screening marker, namely, the yeast Candida ethanothermophilum. The screening marker was seeded on an agar plate to the surface of which agar blocks, each containing a colony of K. pneumoniae, were subsequently fixed. This seeded plate lacked sources of carbon and energy. Ethanol formed in the agar blocks by the K. pneumoniae colonies diffused into the seeded medium and served as a carbon and energy source for the ethanotrophic yeasts. Colonies of yeasts appeared around the agar blocks in regions of ethanolic diffusion. Hyper-ethanolic strains of K. pneumoniae were thus selected on the basis of the number of colonies of the screening marker that appeared around the blocks containing the ethanolic colonies of K. pneumoniae.

Candida↗
PubMed1992

Seroprevalence survey of borreliosis in children with chronic arthritis in British Columbia, Canada.

A seroprevalence survey using an indirect immunofluorescence assay (IFA) for IgG antibodies to Borrelia hermsii and Borrelia burgdorferi was conducted for varied pediatric chronic arthritis patients and a nonrheumatic control group in the province of British Columbia, Canada. Overall, a higher rate of sera with IFA titers > or = 1/256 was found for B. hermsii (36.6%) compared to B. burgdorferi (12.5%). There were no significant differences among the arthritis subgroups and controls for the distribution of IFA titers for either organism. IgG immunoblotting of selected high titered sera to either borrelia species confirmed the lack of specificity of the IFA assay. Serological tests for borreliosis should be cautiously interpreted in children with chronic arthritis.

Adolescent↗
PubMed1991

Propranolol in the treatment of acute migraine attacks.

The efficacy of the beta-adrenoceptor antagonist propranolol in the acute treatment of patients in attacks of either classical (migraine with aura) or common migraine (migraine without aura) headache was assessed in a double-blind placebo-controlled crossover trial with fixed doses. The trial was carried out on 25 patients. The treatment period was set at eight weeks, with the provision of shortening or lengthening it if necessary with a maximum period of seventeen weeks. A minimum of three migraine attacks were treated during each treatment period. Patients were assessed according to: the mean duration and mean severity per treatment period of migraine attacks. The secondary efficacy assessment was made on the basis of the percentage of attacks requiring escape medication per treatment period. The study, based on the t-distribution statistical model with a confidence level of 95%, showed that propranolol had no significant effect in aborting acute attacks of migraine when compared with placebo.

Acute Disease↗
PubMed1991

Enhancement of virulence of Entamoeba histolytica by in vitro liver treatment.

Enhancement of the virulence of five strains of Entamoeba histolytica (three xenically maintained and two axenically maintained) was studied after in vitro incubation with normal hamster liver. Increased virulence was shown by the ability of a small number of liver-treated trophozoites to produce liver lesions in hamsters. Enhancement of virulence was positively correlated with increased resistance to normal hamster serum complement in vitro.

Animals↗
PubMed1991

Pulmonary vascular effects of prostaglandin D2, but not its systemic vascular or airway effects, are mediated through thromboxane receptor activation.

Prostaglandin D2 (PGD2) can cause pulmonary vasoconstriction or vasodilation depending on animal species and age. Because the constrictor effects of PGD2 in some vascular beds may be mediated through thromboxane receptors, the purpose of this study was to determine whether the vascular or bronchial effects of PGD2 are mediated through thromboxane/endoperoxide (TX/E) receptor activation. In chronically instrumented awake sheep, PGD2 (5-25 micrograms/kg i.v.) produced a dose-dependent increase in pulmonary arterial pressure and in systemic arterial blood pressure. These changes were due to increases in resistance, because cardiac output remained unchanged. PGD2 also decreased dynamic compliance at lower doses (0.1-5 micrograms/kg i.v.) than those required to produce pulmonary vasoconstriction, confirming that PGD2 is a potent bronchoconstrictor. The airway and systemic vascular effects of PGD2 were not altered by TX/E receptor antagonism. In contrast, PGD2-induced pulmonary vasoconstriction was blocked by two TX/E receptor antagonists, SQ-29,548 and AH-23848, implying that this effect is mediated through activation of TX/E receptors. The pulmonary vasoconstrictor effects of PGD2 could not be explained by thromboxane generation, because neither cyclooxygenase inhibition with ibuprofen nor thromboxane synthase inhibition with OKY-046 had any effect on PGD2 actions. In contrast, a mild but consistent pulmonary vasodilation produced by PGD2 could be uncovered if the pulmonary vascular bed was preconstricted by hypoxia with simultaneous TX/E receptor blockade. These results indicate that TX/E receptor antagonists, although still useful pharmacological probes to determine the role of TX/E receptor activation in pathophysiological processes, should not be used to infer a role of endogenous thromboxane A2. It is possible that PGD2 participates in pulmonary processes previously ascribed uniquely to thromboxane A2.

Animals↗
PubMed1991

Gastric stromal tumors in two rhesus macaques (Macaca mulatta).

Two female rhesus monkeys (Macaca mulatta, 10 and 24 years old) developed microcytic anemia and became terminally ill. At necropsy, large gastric masses were present, and, in one case, there were widespread abdominal metastases. Except for slightly atypical patterns, at the light microscopic level, the lesions resembled smooth muscle tumors. Ultrastructurally, however, cells in both tumors resembled primitive mesenchyme, while in one of the tumors, there were some characteristics of Schwann cells. No ultrastructural features of smooth muscle were present in either tumor. Vimentin and S-100 were detected immunohistochemically in both tumors. S-100 staining was more intense in the tumor with ultrastructural features of Schwann cells. Actin and desmin were not expressed in either gastric tumor, but diffusely stained a uterine tumor that was concomitantly present in one of the rhesus monkeys. The uterine tumor also exhibited typical ultrastructural features of smooth muscle. In the past, gastrointestinal stromal tumors in all species were thought to be of smooth muscle origin. Recently in human pathology, this conventional viewpoint has given way to the realization that there is a spectrum of neural crest and mesenchymal tumors. We report two gastric stromal tumors in two rhesus monkeys that histologically resembled smooth muscle tumors but were of neuroectodermal and primitive mesenchymal origin.

Animals↗
PubMed1991

A mathematical study of simple exponential modelling in biochemical processes.

This paper discusses the application of simple exponential functions for analyses of complex biochemical processes such as transport phenomena in a mammalian system. The main aim is to identify these exponential function models using various curve fitting techniques. The experimental data used is based on transport of a radio-active tracer 32P (Radio-phosphorus) from a central compartment of blood plasma to subsidiary organ compartments in insulin-treated diabetic rats. The data has been analysed with a view to fitting exponential functions. A graphical method of exponential peeling and six (I to VI) computer programs based on iterative methods for solving single, as well as, multiple exponential functions have been used. The method of exponential peeling has also been compared with the least squares method for simple linear regression. The sum of two exponential functions has been found to be the most preferred Goodness of Fit by the computer programs. This model indicates that the transport of 32P in blood plasma in rats is governed by two major metabolic parameters. Further interpretations of the fitted equations are discussed.

Animals↗
PubMed1991

Effect of antibiotics on polymorphonuclear function in iron deficiency anaemia patients & normal volunteers.

The effect of erythromycin and gentamicin on polymorphonuclear leukocyte (PMN) functions was assessed in normal individuals and in patients with iron deficiency anaemia (IDA) before and after treatment with iron. The PMN phagocytic function was investigated by the standard method. Erythromycin in vivo significantly increased the PMN phagocytic function from 44.18 +/- 2.08 to 57.0 +/- 1.5 at 8 h and the bactericidal activity from 48.33 +/- 1.97 to 56.7 +/- 0.89 at 8 h in the normal adult male volunteers. A significant increase in phagocytic and bactericidal function of PMNs from IDA patients was also observed after in vivo administration of erythromycin. Gentamicin in vitro reduced the bactericidal activity of PMN from normal volunteers (P less than 0.05) but increased the PMN phagocytic activity in normal volunteers and IDA patients.

Adult↗
PubMed1991

Non-sporing anaerobes in hospital sepsis.

In comparison to normal controls, the non-sporing anaerobes were often isolated from orodental sepsis (42% to 44.4%), chronic suppurative otitis media (40%), septic abortion (40.3%), uterocervical wound (45.4%), vaginitis (50%) and cancer cervix (50%). This was true (40%) in perforating ulcers of foot in leprosy. These organisms were less frequently noted in abdominal (11%) and episiotomy (22.8%) wounds and leucorrhoea (33.3%). The role of non-sporing anaerobes was also suggested by the high percentage ratio of number of isolates to number of cases and by its primary isolation in moderate to heavy number. Barring the cases of cancer cervix, the aerobic bacteria were the most common (78.8% to 100%) in all other conditions.

Bacteria, Anaerobic↗
PubMed1990

Pyruvate-induced stimulation of nitrogenase activity in Aulosira fertilissima.

The effect of pyruvate on nitrogenase activity in the N2-fixing cyanobacterium Aulosira fertilissima has been studied. Addition of 0.01-1.0 mM concentrations of pyruvate to actively N2-fixing cultures stimulated the enzyme activity in light; the maximum stimulation was observed with 0.3 mM pyruvate. There was no detectable stimulation of nitrogenase activity in the dark. Addition of pyruvate had no effect on the growth rate. DCMU gradually inhibited nitrogenase activity, but supplementation of 0.3 mM pyruvate to such cultures restored normal activity. Furthermore, pyruvate-induced stimulation of nitrogenase activity was found to be stimulated by anaerobic conditions. The inactivation of nitrogenase activity by the addition of O2 was restored by pyruvate. From 14CO2 uptake studies it appears that the alga preferred to take up pyruvate even in the presence of 14CO2. Thus it appears that pyruvate is taken up and metabolized by the alga, which manifests the observed effects.

Carbon Dioxide↗
PubMed1990

Lung mechanics and airway reactivity in sheep during development of oxygen toxicity.

The causes of respiratory distress in O2 toxicity are not well understood. The purpose of this study was to better define the airway abnormalities caused by breathing 100% O2. Sheep were instrumented for measurements of dynamic compliance (Cdyn), functional residual capacity by body plethysmography (FRC), hemodynamics, and lung lymph flow. Each day Cdyn and FRC were measured before, during, and after the application of 45 min continuous positive airway pressure (CPAP) at 15 cmH2O. The amount of aerosol histamine necessary to reduce Cdyn 35% from baseline (ED35) was measured each day as was the response to aerosol metaproterenol. Cdyn decreased progressively from 0.083 +/- 0.005 (SE) 1/cmH2O at baseline to 0.032 +/- 0.004 l/cm H2O at 96 h of O2. Surprisingly, FRC did not decrease (1,397 +/- 153 ml at baseline vs. 1,523 +/- 139 ml at 96 h). The ED35 to histamine did not vary among days or from air controls. Metaproterenol produced a variable inconsistent increase in Cdyn. We also measured changes in Cdyn during changes in respiratory rate and static pressure-volume relationships in five other sheep. We found a small but significant frequency dependence of compliance and an increase in lung stiffness with O2 toxicity. We conclude that in adult sheep O2 toxicity reduces Cdyn but does not increase airway reactivity. The large reduction in Cdyn in O2 toxicity results from processes other than increased airway reactivity or reduced lung volume, and Cdyn decreases before the development of lung edema.

Animals↗
PubMed1990

Effect of metal chelators on thermoluminescence peaks of spinach chloroplasts and photosystem II particles: probing the water oxidation cycle with 8-hydroxyquinoline.

Inhibition of photosystem II (PS II) activity by 8-hydroxyquinoline (8-HQ) has been investigated in case of spinach chloroplasts and isolated photosystem II particles using the thermoluminescence technique. In presence of 8-HQ, water to methylviologen (MV) photoreduction in isolated chloroplasts is inhibited while the reduction of dichlorophenol indophenol is inhibited in both chloroplasts as well as in photosystem II particles. The activity can be restored fully by addition of diphenylcarbazide (DPC), suggesting that the donor side of water oxidation complex is affected. The changes in the thermoluminescence peaks indicate that the charge recombination processes involving S2 or S3 states of the Kok's cycle are probably affected by 8-HQ treatment.

Chelating Agents↗
PubMed1990

Chemical probes for water oxidation cycle of photosystem II: Part 2--Effect of histidine modifying reagent on thermoluminescence peaks of spinach chloroplasts.

A modification of water oxidation complex in spinach chloroplasts by rose bengal (RB), a known histidine modifying agent, has been studied using thermoluminescence (TL) technique. The changes in the TL profiles at low concentrations of the dye are explained on the basis of alterations in the protein dynamics while those at higher concentrations of the dye are related to the oxidation of histidine residues.

Chloroplasts↗
PubMed1989

Cytological and cytochemical (RNA) studies on rubral neurons after unilateral rubrospinal tractotomy: the impact of GM1 ganglioside administration.

The rubrospinal tract (RST) was cut unilaterally at C2-3 segment in 21 rats that were killed 3, 7, 10, 14, 28, 60, and 90 days later. Additionally, 14 rats, killed 14 or 28 days after lesioning, were treated postoperatively by daily intraperitoneal injections of GM1 ganglioside. Six unoperated, untreated rats served as controls. In untreated animals, axotomized neurons of the magnocellular division of the red nucleus (RN) exhibited cytoplasmic, nuclear, and nucleolar atrophy 7-10 days postoperatively. Atrophy progressed through the 90th postoperative day. Regression analyses disclosed a bimodal pattern to cytoplasmic and nucleolar atrophy, with an initial rapid phase changing to a slower but progressive mode from 14 days postoperatively. Nuclear atrophy proceeded in a unimodal manner. GM1 treatment did not affect these atrophic processes. Neuronal loss did not occur in the axotomized RN through the 60th postoperative day. Axotomized neurons of untreated rats showed significant and progressive reductions in mean somal (cytoplasmic) and nucleolar RNA from, respectively, the 7th and 14th postoperative day. GM1 partly prevented these RNA losses. Both in treated and untreated rats, spinal cord lesions contained many axonal sprouts 2 to 4 weeks after surgery, but newly generated axons did not traverse the rostro-caudal extent of any lesion.

Animals↗
PubMed1989

Kinetics of ethanolic fermentation of D-xylose by Klebsiella pneumoniae and its mutants.

The microbial production of ethanol from D-xylose by a new soil isolate of Klebsiella pneumoniae and the mutants K. pneumoniae MB-16 and MB-16-1048 was studied. Kinetic and physiological properties of the mutants were compared with those of the original isolate. The volumetric rates of ethanol formation by mutants MB-16-1048 and MB-16 and the original isolate were 1.58, 0.50, and 0.06 g liter-1 h-1, respectively. The cultivation times of mutants MB-16-1048 and MB-16 were 20 and 18 h, respectively, and that of the original isolate was 118 h. Both the mutants exhibited metabolic similarities with the original isolate. Ethanol was the major end product of fermentation in all three strains. Acetic acid and carbon dioxide were the other two important by-products of fermentation. Pyruvic acid was accumulated in significant proportions as an intermediate. The proportion of pyruvate in the original isolate was 54% of the total D-xylose utilized, whereas for MB-16 and MB-16-1048 the values were about 42 and 22%, respectively. The lower fractions of pyruvate in mutants MB-16 and MB-16-1048 showed up as a 41 and 82% improvement, respectively, over the original isolate in terms of the ethanol yield.

Acetates↗