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D K Banerjee

Publications and source records attributed to D K Banerjee.

At least 55 records · Page 3Linked to original sources
PubMed1989

Steroid regulation of monoamine oxidase activity in the adrenal medulla.

Administration of different steroid hormones in vivo has distinct and specific effects on the MAO activity of the adrenal medulla. In an effort to reconstitute these effects in defined cells, we have isolated endothelial cells and chromaffin cells from the bovine adrenal medulla and tested each cell type for sensitivity to these steroids. As in the intact animal, we found that endothelial cell MAO activity was stimulated 1.5- 2.5-fold by 10 microM progesterone, hydrocortisone, and dexamethasone, inhibited by ca. 50% by 17-alpha-estradiol, but unaffected by testosterone. The type of MAO in the endothelial cells was found to be exclusively of the A type. The chromaffin cells had MAO B exclusively and were inert to treatment with dexamethasone. The mode of action of the various steroids on MAO A activity in endothelial cells seemed to be that of affecting the number of MAO molecules, as binding of [3H]pargyline, an MAO inhibitor, changed in proportion to changes in enzyme activity. Consistently, the kinetic parameters for MAO A showed changes in Vmax but not Km under all conditions. The specificity of steroid action on MAO A activity was also supported by the fact that steroid-induced changes in total cell division ([14C]thymidine incorporation) and total protein synthesis ([14C]leucine incorporation) were seen after changes in MAO A. We conclude that the differential effects of steroids on MAO activity in the intact adrenal medulla can be reproduced in cultured adrenal medullary endothelial cells but not in chromaffin cells. Therefore we suggest that the action of these steroid hormones on the intact adrenal medulla may be restricted to the endothelial cell component of this tissue.

Adrenal Medulla↗
PubMed1988

Modulation of oligosaccharide processing in an exocrine secretory glycoprotein of rat parotid cells by beta-adrenoreceptor activation.

Such stimulation of rat parotid acinar cells in vitro modulated the rate of processing of N-linked oligosaccharides in a high-molecular weight (220 kdalton) secretory glycoprotein. Conversion of polymannose-type oligosaccharides to complex-type oligosaccharides was evaluated by sensitivity to endoglucosaminidase H and alpha-mannosidase, and with a specific inhibitor of glucosidases I/II. Oligosaccharide maturation in the 220 kdalton glycoprotein required one-third to half less time in cells exposed to the beta-adrenergic agonist isoproterenol than in controls.

1-Deoxynojirimycin↗
PubMed1988

N-linked protein glycosylation in the rat parotid gland during aging.

N-Linked protein glycosylation was examined in vitro in dispersed rat parotid acinar cells from young adult (3-6 months) and aged (22-24 months) rats. A small decrease in general protein production was observed with cells from aged animals (approximately 20% lower incorporation of [14C]leucine into 10% CCl3 COOH insoluble protein during continuous pulse labeling). Incorporation of [3H]mannose into N-linked glycoproteins by aged cells was further reduced (approximately 35%). Similarly microsomal membranes from parotid glands of aged animals showed approximately 50% reduction in the synthesis of mannosylphosphoryl dolichol, a key intermediate in the dolichol pathway of protein N-glycosylation. Man-P-Dol synthase, the microsomal enzyme responsible for production of this saccharide-lipid, displayed no change in apparent Km for GDP-mannose when preparations from aged animals were utilized, but did show approximately 50% reduction in Vmax. Following beta-adrenoreceptor activation, cells from both young adult and aged glands showed increased N-linked protein glycosylation almost to the same extent (approximately 2-fold). The data suggested that in aged rat parotid cells there is a basal reduction of activity in the pathway responsible for asparagine-linked protein glycosylation, but that following exocytotic stimuli this pathway responds in a manner comparable to cells from young adult glands.

Aging↗
PubMed1987

Underdiagnosis of asthma in the elderly.

One hundred and ninety-nine elderly men and women were assessed for their pulmonary function and their mental ability. One hundred and twenty-one patients had a PEFR less than 70% of the predicted for their age and height. Reversibility tests showed that 82 patients had 15% or more improvement in their PEFR following 200 micrograms salbutamol. However, only 6% of the patients were receiving respiratory-related medication. Further analysis showed that there was no correlation between the patients' age, sex, amounts of sputum production, wheeze, breathlessness, smoking habits, chest expansion, hospitalization, mental function and airway reversibility. 'Reversible' patients did, however, have a high incidence of cough and a low pre-test PEFR value. The predominant symptom of 'reversible' and 'non-reversible' patients was cough. The study emphasizes the importance of routinely performing lung function tests in elderly patients and the use of reversibility tests to identify reversible airways obstruction. These results suggest that in old age potentially reversible airways obstruction is often overlooked or misdiagnosed.

Aged↗
PubMed1987

cAMP-mediated protein phosphorylation of microsomal membranes increases mannosylphosphodolichol synthase activity.

We have investigated the possible role of a cAMP-mediated protein-phosphorylation event(s) as the key regulatory mechanism in beta-adrenoreceptor-stimulated activation of mannosylphosphodolichol (Man-P-Dol) synthase (GDP-mannose:dolichyl-phosphate O-beta-D-mannosyltransferase, EC 2.4.1.83) in rat parotid acinar cells. Microsomal membranes isolated from these cells pretreated with 10 microM isoproterenol for 60 min showed approximately 40-80% enhanced Man-P-Dol synthase activity compared to the untreated controls. This change in enzyme activity was not associated with a significant alteration in apparent Km for GDP-mannose, but the Vmax was enhanced 2-fold. When microsomal membranes isolated from control cells were phosphorylated in vitro by a cAMP-dependent protein kinase, an increase in Man-P-Dol synthase activity, similar to that with membranes from isoproterenol-treated cells, was observed (i.e., a moderate change in Km for GDP-mannose but a 2-fold higher Vmax). Furthermore, treatment of in vitro phosphorylated microsomal membranes by alkaline phosphatase led to a substantial reduction in Man-P-Dol synthase activity. Increased Man-P-Dol synthesis (approximately 30-40%) was also observed in bovine brain and hen oviduct microsomal membranes after in vitro protein phosphorylation. In aggregate, these results strongly suggest that agents that increase cAMP in cells may modulate protein N-glycosylation in those cells by activating this key glycosyltransferase of the dolichol cascade by a cAMP-dependent protein kinase-mediated protein phosphorylation/dephosphorylation cycle.

Alkaline Phosphatase↗
PubMed1987

Uptake of norepinephrine and related catecholamines by cultured chromaffin cells: characterization of cocaine-sensitive and -insensitive plasma membrane transport sites.

Norepinephrine and its closely related analogues, dopamine and epinephrine, are transported into chromaffin cells in culture by two distinct types of sites on the plasma membrane: one is sensitive to cocaine while the other is not. The cocaine-sensitive site has a high affinity for catecholamines and depends on sodium in the medium. The apparent Km for norepinephrine uptake by the cocaine-sensitive site is 5.8 microM when determined in the presence of 118 mM NaCl, obtained using nonlinear least-square curve fitting. Detailed kinetic analysis has also shown cocaine to be a competitive inhibitor of norepinephrine uptake with an apparent Ki of ca. 1 microM. This site is blocked by a series of tricyclic antidepressant drugs with relative potencies characteristic of norepinephrine transport sites in neurons. In contrast, the cocaine-insensitive site(s) have a low affinity for norepinephrine (apparent Km, approximately 88 microM) and are also able to transport catecholamine analogues such as dimethyl-epinephrine and isoproterenol, which have bulky groups attached to the amine moiety. Transport of norepinephrine at both sites is blocked by low temperature, by mitochondrial uncouplers, and by other metabolic inhibitors. Both of these transport sites in the chromaffin cell plasma membrane, therefore, appear to be different from the well-characterized catecholamine transport sites in the chromaffin granule membrane on the basis of substrate specificity and their sensitivity to inhibitors.

Adrenal Medulla↗
PubMed1986

Effect of gamma interferon on hydrogen peroxide production by cultured mouse peritoneal macrophages.

Macrophage activation is thought to be mediated via a number of T-lymphocyte products, including gamma interferon (IFN-gamma). However, our studies indicate that IFN-gamma acts as a regulator molecule rather than solely as an activator. This depends upon the status of the macrophage. IFN-gamma treatment of resting macrophages and those activated or elicited by sodium caseinate, lipopolysaccharide, or Mycobacterium bovis BCG did not result in activation, as measured by hydrogen peroxide production; however, when thioglycolate was used as an eliciting agent, incubation with IFN-gamma resulted in a dramatic increase in hydrogen peroxide production compared with that by untreated controls.

Animals↗
PubMed1985

beta-Adrenergic stimulation alters oligosaccharide pyrophosphoryl dolichol metabolism in rat parotid acinar cells.

beta-Adrenergic stimulation of rat parotid acinar cells markedly increases [3H]mannose incorporation into N-linked glycoproteins [Kousvelari, Grant, Banerjee, Newby & Baum (1984) Biochem. J. 222, 17-24]. More than 90% of this protein-bound [3H]mannose was preferentially incorporated into four secretory glycoproteins. The ratio of [3H]mannose/[14C]leucine present in these individual proteins was 1.7-4-fold greater with isoproterenol-treated cells than with untreated controls. In isoproterenol-stimulated cells, [3H]mannose incorporation into mannosylphosphoryl dolichol and oligosaccharide-PP-dolichol was increased 2-3-fold over that observed in unstimulated cells. Similarly, formation of mannosylated oligosaccharide-PP-dolichol was increased approx. 4-fold in microsomes prepared from isoproterenol-treated cells. Also, turnover of oligosaccharide-PP-dolichol was significantly increased (5-fold) by beta-adrenergic stimulation; the half-life for oligosaccharide-PP-dolichol decreased from 6 min in control cells to 1.2 min in isoproterenol-stimulated cells. By 15 min after isoproterenol addition to acinar cells, the specific radioactivity of parotid oligosaccharide moieties increased about 3-fold over the value observed in the absence of the agonist. Taken together, these results strongly suggest that elevation of N-linked protein glycosylation in rat parotid acinar cells after beta-adrenoreceptor stimulation resulted from significant enhancement in the synthesis of mannosylphosphoryl dolichol and oligosaccharide-PP-dolichol and the turnover of oligosaccharide-PP-dolichol.

Animals↗
PubMed1985

beta-Adrenergic activation of glycosyltransferases in the dolichylmonophosphate-linked pathway of protein N-glycosylation.

beta-Adrenoreceptor stimulation of rat parotid acinar cells increases the activity of several microsomal membrane associated, dolichylmonophosphate (Dol-P) linked glycosyltransferases. The activities of Man-P-Dol synthase and Glc-P-Dol synthase are increased by approximately 50%, and the activity of N-acetylglucosaminyl 1-phosphate transferase plus N-acetylglucosaminyl transferase increased by approximately 60%, after agonist treatment. Increases in enzyme activity are (i) independent of endogenous Dol-P levels and (ii) observed under conditions in which the specific activities of donor sugar nucleotides are kept constant. Activation of these enzymes is specific since comparable levels of NADPH-cytochrome c reductase are found in control and agonist-treated membranes. The data thus provide the initial demonstration of neurotransmitter modulation of enzymes in the dolichol-linked pathway of protein N-glycosylation.

Animals↗
PubMed1985

Endothelial cells from bovine adrenal medulla develop capillary-like growth patterns in culture.

The endocrine barrier between chromaffin cells and the blood stream in the adrenal medulla is made of capillary endothelial cells. We have now succeeded in isolating endothelial cells from adrenal medullary tissue, which are probably derived from this barrier. These cells grow on plastic surfaces in the absence of special growth factors or collagen overlays and differentiate into organized structures quite similar to true capillaries. The cells contain factor VIII:R, a marker for endothelial cells, and form intercellular junctions characteristic of capillary endothelial cells. They also synthesize and secrete basal lamina structures and engage in transcytosis, a characteristic ultrastructural and functional combination of exocytosis and endocytosis across the thin endothelial cell processes. These endothelial cells can take up and deaminate catecholamines by A-type monoamine oxidase, an enzyme functionally distinct from the B-type monoamine oxidase found in chromaffin cells. These data indicate that the chromaffin cell and its endothelial cell neighbor may constitute the functional unit of catecholamine metabolism in the adrenal medulla.

Adrenal Medulla↗