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Biomedical subjects

M Banerjee

Publications and source records attributed to M Banerjee.

At least 91 records · Page 5Linked to original sources
PubMed1994

Interaction of ustiloxin A with bovine brain tubulin.

Ustiloxin A is a modified peptide derived from false smut balls on rice panicles, caused by the fungus Ustilaginoidea virens; structurally, it resembles phomopsin A. Ustiloxin A is cytotoxic and is an inhibitor of microtubule assembly in vitro. Because of its resemblance to phomopsin A, we examined its interaction with tubulin and compared the results with those obtained with phomopsin A and dolastatin 10, both of which were found previously to have very similar effects. We determined that ustiloxin A inhibited the formation of a particular intra-chain cross-link in beta-tubulin, as do vinblastine, maytansine, rhizoxin, phomopsin A, dolastatin 10, halichondrin B and homohalichondrin B; this is in contrast to colchicine and podophyllotoxin which do not inhibit formation of this cross-link. Ustiloxin A also inhibited the alkylation of tubulin by iodo[14C]acetamide, as do phomopsin A and dolastatin 10; vinblastine was almost as potent as inhibitor of alkylation as ustiloxin A, whereas maytansine, halichondrin B and homohalichondrin B have little or no effect. In addition, ustiloxin A inhibited exposure of hydrophobic areas on the surface of the tubulin molecule. In this respect, ustiloxin A was indistinguishable from phomopsin A but slightly more effective than dolastatin 10 and considerably more effective than vinblastine; this provides a strong contrast to maytansine, rhizoxin, and homohalichondrin B which have no effect on exposure of hydrophobic areas and to halichondrin B which enhances exposure. Lastly, ustiloxin A strongly stabilized the binding of [3H]colchicine to tubulin. The combination of ustiloxin A with cholchicine stabilized tubulin with a half-life of over 8 days, comparable with results obtained with phomopsin A and colchicine. A comparison of the structures of ustiloxin A, phomopsin A and dolastatin 10 raised the possibility that the strong stabilization of the tubulin structure may require a short segment of hydrophobic amino acids such as the modified valine-isoleucine sequence present in all three compounds. The rest of the structure, specifically the large ring of ustiloxin A and phomopsin A, may serve to place this sequence in an appropriate conformation to interact with tubulin.

Amino Acid Sequence↗
PubMed1994

Purification and characterization of a sperm-binding glycoprotein from human endometrium.

A sialic-acid-binding protein (SABP) was purified to apparent homogeneity from human endometrial scrapings taken at various stages of the menstrual cycle from normal cycling females. The 54 kDa monomer was found to be an O-linked glycoprotein with a total carbohydrate content of 34%. This protein agglutinated washed 2% v/v rabbit red blood cells (RBC) in the presence of calcium. Amongst sialic acids and sialoglycoproteins tested for haemagglutination inhibitory activities, N-glycolyl neuraminic acids and human alpha 1-acid glycoprotein were found to be the most potent, the agglutination activity being totally abolished on desialylation of the RBC in the presence of neuraminidase. Western blot studies showed it to be present in the uterine fluid but absent in normal female serum and in full-term placenta. It was also absent in endometrial homogenates of some cases of unexplained primary infertility. Specific binding studies and Scatchard analysis revealed that 125I-labelled human SABP ligand can bind to human spermatozoa with a Ka = 2.6 x 10(9) M-1, their receptors probably being glycoconjugates having a terminal sialic acid moiety, since the sperm-protein interaction could also be abolished when spermatozoa were desialylated with neuraminidase. The binding occurred specifically on the sperm head plasma membrane and decreased markedly when spermatozoa were previously capacitated in vitro using human serum albumin, implicating the possible loss of a sialoglycoprotein receptor to which the ligand binds during capacitation. The biological importance of this sperm-binding secretory glycoprotein and its functional significance in human reproduction have been discussed.

Adult↗
PubMed1994

Changes in pulmonary vascular tone during exercise. Effects of nitric oxide (NO) synthase inhibition, L-arginine infusion, and NO inhalation.

Nitric oxide (NO) is a potent endogenous vasodilator. Its role in the normal and stressed pulmonary circulation is unclear. To better understand the importance of endogenous NO in normal physiological responses, we studied the effects of altered NO availability on the change in pulmonary vascular tone that accompanies exercise. In paired studies we measured blood flow and pressures in the pulmonary circulation at rest and during treadmill exercise at a speed of 4 mph with and without (a) N omega-nitro-L-arginine, 20 mg/kg intravenously, a selective inhibitor of NO synthase; (b) L-arginine, 200 mg/kg intravenously, substrate for NO synthase; (c) combination of the inhibitor and substrate; and (d) inhalation of NO > 30 ppm, to determine if endogenous release of NO elicits maximal vasodilation. In addition, we sought to determine the site of NO effect in the pulmonary circulation by preconstriction with either U-44619 or hypoxia (fraction of inspired O2 = 0.12) using a distal wedged pulmonary catheter technique. NO synthase inhibition raised pulmonary vascular tone equally at rest and exercise. L-Arginine reversed the effects of NO synthase inhibition but had no independent effect. NO inhalation did not reduce pulmonary vascular tone at rest or enhance the usual reduction in pulmonary vascular resistance with exercise. The effect of NO synthase inhibition was in pulmonary vessels upstream from small veins, suggesting that endogenous NO dilates primarily small arteries and veins at rest. We conclude that, in sheep, endogenous NO has a basal vasodilator function that persists during, but is not enhanced by, exercise.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1993

Airway and vascular effects of 8-epi-prostaglandin F2 alpha in isolated perfused rat lung.

The effects of 8-epi-prostaglandin (PG) F2 alpha, a recently discovered noncyclooxygenase free radical-catalyzed product of arachidonic acid, on pulmonary vascular and airway tone, its potency, and its mechanism of action were studied. Progressively increasing bolus doses (1.0, 5.0, 10.0, and 20.0 micrograms) of 8-epi-PGF2 alpha were injected into the pulmonary artery catheter of 18 isolated rat lungs, and a single dose (40.0 micrograms) was injected into 7 additional rat lungs. The lungs were perfused with Krebs-Henseleit buffer solution containing 3% bovine serum albumin at 50 ml.kg-1.min-1 during ventilation with 21% O2-5% CO2-74% N2. 8-Epi-PGF2 alpha caused rapid pulmonary vascular and airway constrictor responses, which were followed by a gradual return over 10 min to baseline levels. Double vascular occlusion at peak rise in pulmonary arterial pressure (Ppa) revealed a 28% increase in arterial resistance. The rise in Ppa with 20 micrograms of 8-epi-PGF2 alpha was approximately twofold greater than with 20 micrograms of the cyclooxygenase-derived prostaglandin PGF2 alpha. The addition of 100 microM N-nitro-L-arginine, a blocker of endothelium-derived relaxing factor, in the perfusate potentiated the rise in Ppa by 244%. Injection of 40 micrograms of rat atrial natriuretic factor at peak response to 20 micrograms of 8-epi-PGF2 alpha accelerated the return to baseline Ppa, resistance to airflow across the lung, and dynamic lung compliance values.(ABSTRACT TRUNCATED AT 250 WORDS)

Air Pressure↗
PubMed1993

Effects of rhGM-CSF on myeloid clonogenic cells in acute myelogenous leukemia patients.

The effects of rhGM-CSF in vivo on the myeloid clonogenic cells present in 6 AML patients was evaluated. The relative number of clonogenic cells fell in 4 of the 6 patients. The effects of rhGM-CSF on the percentage of clonogenic cells in S phase and the sensitivity of clonogenic cells to cytosine arabinoside varied among the patients. These effects were not related to the effects of rhGM-CSF on the white blood cell count or on the proliferative rate of the leukemia cell population as a whole.

Adult↗
PubMed1992

Sumatriptan in the treatment of acute migraine with aura.

The efficacy of the selective 5HT1-like agonist sumatriptan in acute treatment of classical migraine (i.e. migraine with aura) was assessed in a double-blind, placebo-controlled, parallel group randomized trial. An oral dose of 200 mg was chosen on the basis of the efficacy rates achieved (70-85%) with 70-280 mg in open studies (1, 2). The dose of 200 mg was also chosen for the study because preliminary data from an oral pilot study indicated that efficacy increased with increasing dose up to 200 mg. Each patient was treated for a maximum of three separate attacks of migraine with aura within a three months' period. Three attacks were treated so that we could examine consistency of response across more than one attack. For attack 1, 200 mg sumatriptan was significantly more effective, safe and well tolerated than placebo at relieving headache 2 h after treatment was given (p = 0.023). In subsequent attacks, i.e. in attacks 2 and 3, there was no such significant effect of sumatriptan compared with placebo in relieving headache. This reduced efficacy of sumatriptan in the second and third attacks may be due to a high incidence of vomiting induced by the high dose of dispersible formulation and also by the bitter taste of the tablets. In addition, there was an increase in placebo response in attacks 2 and 3 compared to the first attack.

Acute Disease↗
PubMed1992

Effects of a novel prostaglandin, 8-epi-PGF2 alpha, in rabbit lung in situ.

We determined the effects of 8-epiprostaglandin (PG) F2 alpha, a noncyclooxygenase free radical-catalyzed product of arachidonic acid, on pulmonary vascular tone, its potency, and its mechanism of action. 8-Epi-PGF2 alpha (0.5-20 micrograms) was injected into the pulmonary artery (PA) catheter of 10 rabbits whose lungs were perfused in situ with Krebs-Henseleit buffer solution with 3% bovine serum albumin. PA pressure increased from a baseline of 13.5 +/- 0.6 to 25.6 +/- 2.0 cmH2O with 20 micrograms 8-epi-PGF2 alpha. 8-Epi-PGF2 alpha caused a rapid rise in PA pressure followed by a gradual decline over 40-60 min to baseline levels. Double vascular occlusion revealed a twofold increase in arterial resistance at peak rise in PA pressure. The rise in PA pressure with 20 micrograms 8-epi-PGF2 alpha was fivefold greater than with 20 micrograms of the cyclooxygenase-derived prostaglandin PGF2 alpha. The PA pressure response to 8-epi-PGF2 alpha was not altered by either cyclooxygenase block-ade with 150 microM meclofenamate or alpha-receptor blockade with 70 microM phentolamine, but was fully prevented by 40 microM SQ 29548, a thromboxane receptor antagonist. We conclude that in rabbits 8-epi-PGF2 alpha is a potent vasoconstrictor of the pulmonary vasculature, which appears to be due to the activation of SQ 29548-responsive thromboxane receptors.

Animals↗
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↗