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Biomedical subjects

D K Sharma

Publications and source records attributed to D K Sharma.

67 records · Page 4Linked to original sources
PubMed1984

Nucleus locus coeruleus: evidence for alpha 1-adrenoceptor mediated hypotension in the cat.

Microinjection of noradrenaline or phenylephrine into the nucleus locus coeruleus of cats induced a dose dependent and long lasting hypotension. Clonidine was required in a dose of 1 microgram for eliciting a significant hypotension while its lower doses (up to 500 ng) failed to elicit any significant cardiovascular alteration. The effects on heart rate evoked by these agents were insignificant. Microinjection of alpha-adrenoceptor antagonists prazosin, piperoxan and RX 781094 per se did not evoke any significant cardiovascular effects and only prazosin pretreatment showed dose dependent antagonism of the hypotensive effect of clonidine. Piperoxan was required in four times higher dose (20 micrograms) to partially antagonize the clonidine induced hypotension. RX 781094, a selective alpha 2-adrenoceptor antagonist, however, even up to a dose of 20 micrograms (four times that of prazosin) did not alter the effect of clonidine. Similar pattern of antagonism was also seen for noradrenaline and phenylephrine. The results demonstrate the presence of alpha 1-adrenoceptors in the nucleus locus coeruleus, the activation of which leads to a fall in blood pressure.

Adrenergic alpha-Antagonists↗
PubMed1983

Evidence for involvement of alpha 2-adrenoceptors in the nucleus ambiguous in baroreflex-mediated bradycardia.

Microinjection of noradrenaline and clonidine into the nucleus ambiguus elicited dose-dependent bradycardia with insignificant alteration of blood pressure. Phenylephrine failed to elicit any cardiovascular effect. The bradycardic effects of noradrenaline and clonidine were antagonized by piperoxan but not by phenoxybenzamine. Adrenergic neurone blockade with local guanethidine pretreatment also abolished the response to clonidine. No significant cardiovascular effect of clonidine microinjection into the nucleus ambiguus was observed in bilaterally vagotomized animals. The baroreflex bradycardia induced by volume loading as abolished by yohimbine and piperoxan but not by phenoxybenzamine, microinjected bilaterally into the nucleus ambiguus. These results demonstrate the presence of cardioinhibitory, presynaptic alpha 2-adrenoceptors in the nucleus ambiguus and their involvement in baroreflex bradycardia.

Adrenergic alpha-Agonists↗
PubMed1978

Significance of thymus-derived lymphocytes in immunity elicited by immunization with ribosomes or live yeast cells of Histoplasma capsulatum.

The lymphoid cells responsible for protective immunity to histoplasmosis were characterized. Adoptive transfer of spleen and peritoneal cells treated with antiserum to theta-antigen from mice immunized with ribosomes or live yeast cells of Histoplasma capsulatum abrogated the ability of these cells to protect the syngeneic recipients, whereas treatment of lymphoid cells with antiserum to IgG did not affect the immunity. Prior removal of glass-adhering cells from spleen and peritoneal cell suspensions did not alter their protective activity. Treatment with mitomycin C, an antimitotic agent, ablated the capacity of immune lymphocytes to protect the syngeneic recipients. These results indicate that the immune spleen and peritoneal cells that confer immunity to histoplasmosis are thymus-dependent (T) lymphocytes and that their active proliferation in the recipients is necessary for expression of the protective immunity. Furthermore, the immunity elicited by immunization with histoplasma ribosomes and live yeast cells is mediated by a similar mechanism.

Adhesiveness↗
PubMedDate not supplied

Hypolipidemic, anti-inflammatory, and antineoplastic activity and cytotoxicity of flavonolignans isolated from Hydnocarpus wightiana seeds.

Flavonolignans isolated from Hydnocarpus wightiana seeds, namely hydnowightin, hydnocarpin, and neohydnocarpin, demonstrated potent hypolipidemic activity in mice, lowering both serum cholesterol and triglyceride levels at 8 mg/kg/day ip. Hydnowightin demonstrated the best lipid-lowering effect of the three compounds. Good anti-inflammatory and antineoplastic activity was demonstrated by hydnocarpin in mice in vivo. The other two derivatives were not as active in these screens. Cytotoxicity against the growth of murine and human tissue cultured cells was shown. All three compounds were moderately active against murine L-1210 leukemia growth. All three compounds demonstrated good activity against the growth of human KB nasopharynx, colon adenocarcinoma, osteosarcoma, and HeLa-S3 uterine growth. Hydnocarpin was the only compound of the three which was active against glioma growth. Hydnocarpin and neohydnocarpin demonstrated significant activity against Tmolt3 leukemia cell growth.

Animals↗
PubMedDate not supplied

A new spectrophotometric method for the determination of dithianon in commercial formulations and its residues in foodstuffs.

A new, simple, and rapid spectrophotometric method for the microdetermination of dithianon, on the basis of its reaction with a dithiocarbamate, is described. The red color, which develops instantaneously when mixing the fungicide with the reagent in acetonitrile, is stable for at least 1 h and is measured at 520 nm. Beer's law is applicable up to 12 micrograms/mL dithianon concentration. The method has been successfully adapted to the analysis of the fungicide in commercial formulations and its residues on grains and apple (fruit and leaves). A photometric titration method for formulation analysis of the fungicide has also been developed.

Acetonitriles↗
PubMedDate not supplied

Visceral larva migrans.

We present a case of visceral larva migrans which came as a complete histologic surprise. The patient was operated as a case of chronic cholecystitis and was found at operation to have multiple hepatic nodules. A cholecystectomy with a biopsy of the liver nodule was performed. Histopathologically a diagnosis of visceral larva migrans was made. To our knowledge this is the first case report of the disorder from India. A discussion based on the review of literature is presented.

Biopsy↗