Search PubMed⌕ Search

Biomedical subjects

S Sengupta

Publications and source records attributed to S Sengupta.

At least 217 records · Page 12Linked to original sources
PubMed1986

Novel heterophile chicken antigen: immunohistochemical localization using antisera to Mycobacterium smegmatis and possible association with lymphocyte maturation.

A novel heterophile antigen shared by Mycobacterium smegmatis and chicken tissues was demonstrated by the indirect immunoperoxidase method using antisera raised in rabbits immunized with a complete Freund's adjuvant containing killed Mycobacterium smegmatis as an immunostimulating component. This antigen was strongly expressed in medullary lymphocytes of the thymus and bursa of Fabricius, but was undetectable in lymphoid cells of the cortical regions of these organs. Only a few lymphocytes stained positively for the antigen in T- and B-cell areas of the spleen. These data suggest that the heterophile antigen is associated with the intrathymic and intrabursal maturation of chicken lymphocytes. The antigen was also detected in some nonlymphoid cells. It was not found in sheep erythrocytes, human and rat tissues or in killed bacillus Calmette--Guerin.

Animals↗
PubMed1986

Mutagenesis of Protoplasts and Regeneration of Mycelium in the Mushroom Volvariella volvacea.

Regenerating protoplasts were obtained from mycelial culture of the mushroom Volvariella volvacea by the action of the lytic enzyme Novozym 234 in the presence of 0.01 M phosphate buffer (pH 6.0) containing 0.6 M NaCl. Regeneration was found to be poor in liquid medium, but more than 50% regeneration was achieved on solid 2% agar medium overlaid with 0.5% agar. Protoplasts of V. volvacea were found to be highly sensitive to the killing action of both UV irradiation and N-methyl-N'-nitro-N-nitrosoguanidine. However, no morphological or auxotrophic mutants could be obtained from protoplasts by chemical mutagenesis. Four types of morphological mutants and one auxotrophic (adenine-negative) mutant were obtained from UV-irradiated protoplasts. The adenine-negative mutant of V. volvacea was found to be stable, not losing auxotrophy on repeated subculture.

Journal Article↗
PubMed1985

Immunomorphological localization of adenosine deaminase in rat tissues during ontogeny.

Immunomorphological methods were used to localize adenosine deaminase in tissues of the rat at different stages of ontogeny. In the thymus, lymphocytes began to express significant amounts of the enzyme with the appearance of demarcation between the cortex and medulla at 17 days of gestation. At any stage of ontogeny studied, strong adenosine deaminase staining was seen predominantly in cortical thymocytes. In the spleen and lymph node, the enzyme was initially detected in T cell areas, whereas primary follicles did not show positive adenosine deaminase staining. During further development, the enzyme was demonstrated in some lymphocytes of germinal centres and plasma cells. In the duodenum, epithelial cells of villi and the neck of crypts showed positive adenosine deaminase staining whereas no staining for the enzyme was observed in the epithelial cells of the base of crypts. Strongly positive staining for adenosine deaminase appeared in plasma cells of the lamina propria by four weeks after birth. The transient positive reaction for the deaminase could be recognized in epithelial cells of tubules of the kidney during late foetal and early postnatal development. The tubules of adult rats did not stain for the enzyme. In the cartilage of 15-day foetuses, positive adenosine deaminase staining was seen only in perichondrial cells and hypertrophic cells. Kupffer cells in the liver and endothelial cells of blood vessels stained positively for the enzyme at every stage of ontogeny studied.

Adenosine Deaminase↗
PubMed1985

Purification and properties of an endo-alpha-mannan hydrolase from the mushroom Volvariella volvacea.

The enzyme, endo-alpha-mannanase, from culture filtrate of a mushroom Volvariella volvacea has been purified 73-fold by acetone precipitation, ion-exchange chromatography (DEAE-Sephadex), and gel-permeation chromatographies on Bio-Gel P-300 and on Sephacryl S-200 columns. The enzyme preparation gave a single protein band on sodium dodecyl sulfate-disc gel electrophoresis at pH 6.8 and has a molecular weight of approx. 56,000. It has no alpha- or beta-mannosidase activity and does not act on beta-gluco-or galactomannan. The enzyme shows maximum activity on baker's yeast alpha-mannan at pH 5.0 and at 55 degrees C, and is fairly stable between pH 3 and 6 and temperatures up to 50 degrees C. The Km is 32.25 mg mannan/ml. Enzyme activity is inhibited by Hg2+, sodium azide, iodoacetic acid, EDTA, and Ag+, in decreasing order.

Basidiomycota↗
PubMed1985

Characterization of the hypotensive action of dopamine receptor agonists fenoldopam and quinpirole in anaesthetized rats.

The present study was designed to examine the cardiovascular actions of fenoldopam, a DA1-receptor agonist, and quinpirole, a DA2 receptor agonist, in pentobarbital-anaesthetized rats. Fenoldopam (20, 40 and 80 micrograms/kg) produced short lasting decreases in blood pressure accompanied by tachycardia. Quinpirole (20 and 80 micrograms/kg) caused hypotension and bradycardia which lasted throughout the one hour observation period. The DA1-receptor antagonist SCH 23390 almost completely abolished the hypotensive action of fenoldopam without affecting the hypotension or bradycardia seen with quinpirole. The mixed dopamine receptor antagonist, RS-sulpiride and the selective DA2-receptor antagonist, S-sulpiride, antagonized the cardiovascular actions of quinpirole. These compounds also blocked the hypotension seen with the lowest dose of fenoldopam, but this antagonism was of lesser magnitude than that produced by SCH 23390. Fenoldopam also produced hypotension when given to pithed rats after their resting blood pressure was restored to control level by noradrenaline infusion. This hypotensive action of fenoldopam was antagonised by SCH 23390. Quinpirole, on the other hand, failed to exert any effect in pithed rats. Our results show that fenoldopam and quinpirole produce their cardiovascular actions via activation of DA1- and DA2-receptors respectively. These selective dopamine receptor agonists and the selective DA1-receptor antagonist, SCH 23390 offer novel pharmacological probes for characterization of dopamine receptor subtypes in the kidney and other peripheral organs.

Anesthesia↗
PubMed1984

Allogeneic lymphocyte cytotoxicity in rats: the effects of various pharmacological agents.

In a number of strain combinations among inbred rats, intravenously injected 51Cr-labelled lymphocytes are rapidly destroyed by unsensitized allogeneic hosts. This phenomenon has previously been referred to by a number of terms, the most explicit and least confusing of which is allogeneic lymphocyte cytotoxicity (ALC). It is characterized by reduced lymph node radioactivity, together with increased kidney and/or urine radioactivity 24 hr after injection, in allogeneic hosts as compared with syngeneic recipients of the same cell suspension. ALC has a number of features in common with other natural resistance systems. Nevertheless, the administration of hydrocortisone or silica in doses comparable to those causing diminished NK activity in rats was without effect on ALC; likewise cyclophosphamide at a dose capable of significantly impairing NK activity in rats had, at most, a minor effect on ALC. Under the conditions of administration cyclosporin A was without effect. The interferon inducer polyinosinic polycytidilic acid (poly I:C) brought about a significant augmentation of ALC.

Animals↗
PubMed1983

Localization and identity of adenosine deaminase-positive cells in tissues of the young rat and calf.

Rabbit antibody to calf adenosine deaminase (ADA) was used to localize this enzyme in tissues of the young rat and calf by the immunoperoxidase method. The distribution patterns of ADA in most tissues were similar for both species. Within the thymus gland, the enzyme was strongly expressed predominantly in cortical lymphocytes. In the spleen and lymph nodes, most lymphocytes of T-cell areas stained weakly for ADA, whereas only a small number of ADA-positive cells were found in B-cell areas. Clumps of strongly ADA-positive mononuclear blastoid and plasma cells were observed in the medullary regions of lymph nodes, around peri-arteriolar lymphocyte sheaths and in the red pulp of the spleen, and in the lamina propria of the intestine. Double immunofluorescence staining studies in the rat showed that some of these blastoid cells contained both ADA and immunoglobulins and appeared to be plasmablasts. Strong staining for ADA was also found, in both the rat and calf, in as yet unidentified mononuclear blastoid cells in the interstitium of non-lymphoid organs (kidney, heart, lung), in endothelial cells of some arterioles and capillaries, and in Kupffer cells of the liver. In addition, ADA was strongly expressed in calf bile canaliculi. These studies define areas in rat and calf tissues which contain ADA-positive cells and provide a model system for investigations of the relationship between ADA and the function and development of these cells.

Adenosine Deaminase↗