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Biomedical subjects

R K Sharma

Publications and source records attributed to R K Sharma.

At least 379 records · Page 21Linked to original sources
PubMed1989

Mycotic infection of the ear (otomycosis): a prospective study.

Otomycosis (fungal infection of the ear) is not uncommon clinical problem encountered in our ENT practice. It makes up to 6 per cent of all patients with symptoms of ear disease seen in the Outpatient Clinic. Of the 193 patients with a clinical diagnosis of otomycosis, 171 cases produced positive fungal isolates. In this study Aspergillus species (niger and fumigatus) have been the most common fungal pathogens. Various aetiopathological factors have been examined in detail, and the available literature reviewed. The results of the treatment by nine antifungal agents currently available in Bahrain have been analysed.

Adolescent↗
PubMed1989

Maxillary antral lavage--infiltration and surface anaesthesia compared.

A prospective study on 210 patients was conducted to determine the relative efficacy of infiltration anaesthesia as against surface anaesthesia for antral lavage. The patients were categorized into three groups and comparisons were made on patient response and our observations. This study confirms that infiltration technique is superior to surface anaesthesia and is, also, less time consuming.

Administration, Topical↗
PubMed1989

Histomorphological changes in the oviduct of the mallard (Aves: Anatidae).

Studies on histomorphometrical changes in different segments (infundibulum, magnum, isthmus, shell gland and vagina) of oviduct of mallard, Anas platyrhynchos during active and quiescent phases of the reproductive cycle have been made. The absolute and per cent length and width of each segment showed a marked change. The magnum showed an increase of 280 per cent. Of all the histological parameters studied the number and height of mucosal folds and mucosal epithelium showed more marked increase in all segments of oviduct. The size of tubular glands and frequency of ciliated and secretory cells were studied in relation to oviductal activity.

Animals↗
PubMed1988

Characterization and regulation by protein kinase C of renal glomerular atrial natriuretic peptide receptor-coupled guanylate cyclase.

The nature and regulation of atrial natriuretic peptide (ANP)-sensitive guanylate cyclase in rat renal glomerular membranes was examined. By affinity crosslinking techniques, three bands with apparent molecular masses of 180, 130 and 64 kDa were specifically labeled with [125I]ANP. A specific antibody to the 180 kDa membrane guanylate cyclase of rat adrenocortical carcinoma recognized a 180 kDa band on Western blot analysis of solubilized, GTP-affinity purified glomerular membrane proteins. The same antibody completely inhibited ANP-stimulated guanylate cyclase activity in glomerular membrane fractions. Partially purified protein kinase C inhibited ANP-stimulated guanylate cyclase activity in glomerular membrane fractions. It is concluded that a 180 kDa ANP-sensitive guanylate cyclase is present in glomerular membranes, and that this enzyme is inhibited directly by protein kinase C.

Affinity Labels↗
PubMed1988

Inhibition of alpha 2-adrenergic receptor-mediated cyclic GMP formation by a phorbol ester, a protein kinase C activator.

alpha 2-adrenergic receptor-mediated signal transduction in rat adrenocortical carcinoma cells occurs through the opposing regulation of two second messengers, cyclic GMP and cyclic AMP, in which guanylate cyclase is coupled positively and adenylate cyclase negatively to the receptor signal. We now show that in these cells phorbol 12-myristate 13-acetate (PMA), a known activator of protein kinase C, inhibits the alpha 2-agonist (p-aminoclodine)-dependent production of cyclic GMP in a dose-dependent and time-dependent fashion. The half-maximal inhibitory concentration of PMA was 10(-10) M. A protein kinase C inhibitor, 1-(5-isoquinolinyl-sulfonyl)-2-methyl piperazine (H-7), caused the release of the PMA-dependent attenuation of p-aminoclodine-stimulated cyclic GMP formation. These results suggest that protein kinase C negatively regulates the alpha 2-receptor coupled cyclic GMP system in these cells, a feature apparently shared with the other cyclic GMP-coupled receptors such as those of muscarine, histamine, and atrial natriuretic factor.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1988

Characterization of atrial-natriuretic-factor-receptor-coupled membrane guanylate cyclase from rat and mouse testes.

Studies with isolated adrenal cells and mouse testicular cells have supported a mediatory role of cyclic GMP in ANF (atrial natriuretic factor)-dependent steroidogenic signal transduction. This concept has been strengthened by the purification and biochemical characterization of a 180 kDa protein, which appears to contain both ANF receptor and guanylate cyclase activities, from rat adrenocortical carcinoma cells. Utilizing the antibody to 180 kDa membrane guanylate cyclase as a probe, we now demonstrate the direct presence of ANF-dependent membrane guanylate cyclase in mouse and rat testes. The antibody blocks the ANF-dependent guanylate cyclase activity in isolated membranes, and Western-blot analysis of the partially purified enzyme reveals a single 180 kDa protein. The presence of this enzyme in mouse and rat testes, together with its previous demonstration in rat adrenocortical carcinoma, represent an important potential biochemical role for this enzyme in receptor-mediated steroidogenic signal transduction.

Animals↗
PubMed1988

Negative regulation of atrial natriuretic factor receptor coupled membrane guanylate cyclase by phorbol ester. Potential protein kinase C regulation of cyclic GMP signal in isolated adrenocortical carcinoma cells of rat.

Rat adrenocortical carcinoma cells possess a high density of atrial natriuretic factor (ANF) receptors which are coupled with membrane guanylate cyclase and corticosterone production. Herein we show that pretreatment of these cells with phorbol 12-myristate 13-acetate (PMA), a known activator of protein kinase C, attenuates the ANF-stimulated cyclic GMP accumulation in a dose-dependent manner. The half maximum inhibitory concentration of PMA was 10(-10) M. When these cells were incubated with PMA in the presence of 1-(5-isoquinolinyl-sulfonyl)-2-methyl piperazine, a protein kinase C inhibitor, the PMA-mediated attenuation of ANF-stimulated cyclic GMP formation is blocked. These results suggest that protein kinase C negatively regulates the ANF-receptor coupled membrane guanylate cyclase system in these cells.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1988

Effects of STS 557 on semen and sperm functions in bonnet monkey (Macaca radiata)--a preliminary report.

Intramuscular administration of STS 557 (17 alpha C-cyanomethyl-17 beta-hydroxy-estra-4,9(10)-diene-3-one) at a daily dose of 12 mg/monkey for 8 weeks induced severe oligospermia to complete azoospermia by the 9th week of initiation of treatment with concomitant decrease in the serum level of testosterone. The sperm motility was reduced from the 3rd week of treatment. Complete recovery was observed by the 14th week after withdrawal of treatment. STS 557 may have the potentiality to be used as a chemical contraceptive in the male.

Acid Phosphatase↗
PubMed1988

Haemangiopericytoma of the nasal septum.

Haemangiopericytoma is a rare vascular tumour originating from pericytes which are cells surrounding the capillaries. Only 23 cases of haemangiopericytoma arising from the nose and sinuses have been reported in the literature, of which three are from the nasal septum. We are pleased to report one more case.

Adult↗
PubMed1988

Odontogenic keratocyst involving the maxillary antrum.

An unusual case of odontogenic keratocyst arising from the maxilla, involving the maxillary antrum has been reported. Presence of an ectopic canine tooth under the orbital floor was a noticeable feature of this case. The clinical presentation, radiological, and histological aspects and treatment have been reviewed.

Adult↗
PubMed1987

Coexistence of guanylate cyclase and atrial natriuretic factor receptor in a 180-kD protein.

Atrial natriuretic factor (ANF) is a peptide hormone that is released from atria and regulates a number of physiological processes, including steroidogenesis in adrenal cortex and testes. The parallel stimulation of membrane guanylate cyclase and corticosterone production in isolated fasciculata cells of rat adrenal cortex has supported the hypothesis of a mediatory role for cyclic guanosine monophosphate (cyclic GMP) in signal transduction. A novel particulate guanylate cyclase tightly coupled with ANF receptor was purified approximately 273,000-fold by two-step affinity chromatography. The enzyme had a molecular size of 180 kilodaltons and was acidic in nature with a pI of 4.7. Its specific activity was 1800 nanomoles of cyclic GMP formed per minute per milligram of protein. The purified enzyme bound ANF with a specific binding activity of 4.01 nanomoles per milligram of protein, a value that is close to the theoretical binding activity of 5.55 nanomoles per milligram of protein for 1 mole of the ligand binding 1 mole of the receptor protein. These results indicate that the guanylate cyclase-coupled ANF receptor exists in a 180-kilodalton protein of rat adrenocortical carcinoma and represent a step toward the elucidation of the basic mechanism of cyclic GMP-mediated transmembrane signal transduction in response to a hormone.

Adrenal Cortex↗
PubMed1987

Effect of parbendazole and piperazine adipate on the activity of some enzymes of Ascaridia galli and Heterakis gallinae.

Adult Ascaridia galli and Heterakis gallinae obtained from the fowl (Gallus gallus) were treated in vitro with 10(-2) to 10(-5) M parbendazole and piperazine adipate for 10-60 min at 38 degrees C. Both the compounds at 10(-2) M caused mortality of A. galli and H. gallinae after a maximum of 30 min exposure. The effect of the drugs on the homogenates of the treated worm was investigated. Parbendazole (10(-2) M) inhibited malate oxidation by 68% in A. galli and 62% in H. gallinae. Piperazine adipate (10(-2) M) inhibited malate oxidation by 78% in both parasites. In A. galli oxaloacetate reduction was inhibited by 41 and 26% by 10(-2) M parbendazole and piperazine adipate, respectively; with H. gallinae this inhibition was found to be 39 and 55%, respectively. Aldolase activity in both the parasites was also inhibited by 10(-2) M parbendazole and piperazine adipate. Both compounds caused an inhibition of acid phosphomonoesterase activity, but the activities of lactate dehydrogenase and alkaline phosphomonoesterase were not affected significantly. Parbendazole (10(-2) M) had no significant effect on the cholinesterase activity of these parasites, but piperazine adipate (10(-2) M) caused an inhibition of 96% in A. galli and 93% in H. gallinae. The possible mode of action of the drugs is discussed.

Acid Phosphatase↗