Search PubMed⌕ Search

Biomedical subjects

R Sharma

Publications and source records attributed to R Sharma.

At least 451 records · Page 25Linked to original sources
PubMed1993

A novel role for calcium and membrane-binding proteins in regulation of respiratory burst in Ehrlich ascites tumour cells.

The effect of the signals, dexamethasone and phorbol-ester (TPA) and their interplay on the respiratory burst in Ehrlich ascites tumour (EAT) cells and the effect of this interplay has on the phosphorylation state and thus function of EAT cell cytosolic calcium and membrane-binding proteins (CaMBPs) was studied. Dexamethasone (1 mg/kg body weight) inhibited basal and TPA-activated EAT cell respiratory burst. CaMBPs isolated from EAT cells under the influence of either or both signals by a membrane-affinity binding technique showed similar profiles on SDS-PAGE. Autoradiography showed that only an 11,000 M(r) protein is subject to phosphorylation and that dexamethasone brings down the extent of phosphorylation of CaMBPs isolated from control and TPA-treated EAT cells. Phosphorylated CaMBPs from control and TPA-treated cells could activate the respiratory burst in Triton-permeabilized EAT cells in a dose-dependent manner (four- and six-fold activations, respectively, at 16 micrograms protein concentration) when included in the assay, whereas dephosphorylated CaMBPs from EAT cells from mice treated with dexamethasone alone, or later activated with TPA, could not. A phosphatase activity was detected in EAT cell cytosol receiving the dual-signal, dexamethasone and TPA.

Animals↗
PubMed1993

Is spermatozoan acrosin a predictor of fertilization and embryo quality in the human?

OBJECTIVE: To investigate whether acrosin is a more reliable criterion than conventional parameters for assessing semen samples. DESIGN: Total acrosin was estimated biochemically in semen samples obtained for routine screening for infertility and for IVF-ET procedures. SETTING: Assisted Conception Unit, St. James's University Hospital, Leeds, United Kingdom. PATIENTS: Four hundred sixty-three couples being investigated for causes of infertility, and 132 couples undergoing IVF-ET for any indication except antisperm antibodies between 1990 and 1991 were included in the study. INTERVENTIONS: Semen samples were collected as part of routine investigation. Samples from men with consistently high viscosity were collected in alpha-chymotrypsin. MAIN OUTCOME MEASURES: Total spermatozoan acrosin in motile spermatozoa and motile spermatozoan density in couples being assessed for IVF-ET and fertilization and embryo quality in those receiving treatment are considered. RESULTS: Total acrosin levels were less variable (within subject) than either total or motile spermatozoan concentration at ejaculation. Although severely oligozoospermic ejaculates had the lowest levels of total acrosin, overall, there was no significant correlation of spermatozoan concentration between total acrosin levels and percentage fertilization. CONCLUSIONS: Total spermatozoan acrosin activity correlates positively with fertilization rates but not with spermatozoan count. Motile spermatozoan density for insemination may be adjusted to achieve > 7.5 microIU acrosin per oocyte, without compromising fertilization or further embryo development to blastocysts in vitro.

Acrosin↗
PubMed1993

Identification of photo-inactive phytochrome A in etiolated seedlings and photo-active phytochrome B in green leaves of the aurea mutant of tomato.

The contents of spectrophotometrically measurable phytochrome A (PhyA) and phytochrome B (PhyB) and the corresponding immunochemically detectable apoproteins (PHYA and PHYB) were examined in dark- and light-grown tissues of the aurea mutant of tomato and its wild-type (WT). The amount of PHYA in etiolated aurea seedlings was found to be about 20% of that in the WT; this PHYA showed no photo-reversible changes in absorbance, no downregulation of the level of PHYA in light-grown seedlings, and no differential proteolysis of Pr and Pfr species in vitro which was seen in the case of the WT. By contrast, the amount of PHYB in aurea seedlings was not significantly different from that in WT seedlings. Phytochrome isolated from green leaves of the aurea mutant and purified by ion-exchange chromatography showed a red/far-red reversible spectral change, and its elution profile during chromatography was essentially similar to that of PHYB. The results indicate that aurea is a mutant that is deficient in photoactive PhyA at the etiolated stage, when it contains a spectrally inactive PHYA. However, the mutant contains spectrally active PhyB in its green tissue as does the WT.

Enzyme Activation↗
PubMed1993

Effect of radiation on glyoxalase I and glyoxalase II activities in spleen and liver of mice.

Swiss albino mice (7-8 weeks old) were irradiated with different doses (0-25 Gy) of gamma-radiation at a dose-rate of 0.05 Gy/s. The specific activities of glyoxalase I (GI) and glyoxalase II (GII) were determined in the spleen and liver immediately and on the 3rd and 6th day postirradiation. The results indicate that the glyoxalase system is radiosensitive, particularly glyoxalase I whose activity was enhanced even at low doses (0.5 Gy). The magnitude and mode of the radiation effect depends on dose and tissue. The patterns of the GI/GII ratio in the liver and spleen was very similar when measured immediately after irradiation. The radiation effect on the glyoxalase system persists even in the postirradiation period and was inversely related to the dose-rate. GSH and caffeine increased and chlorpromazine decreased the radiation-induced activity of GI, but all three modifiers enhanced radiation-induced inactivation of GII. Since the glyoxalase system may play an important role in the regulation of cell division and differentiation, radiation effects on this system may have some biochemical consequences.

Animals↗
PubMed1993

Postpartum hemorrhage producing acute ischemic optic neuropathy.

A rare case of bilateral peripartum blindness due to acute ischemic optic neuropathy (AION) occurring after an episode of postpartum hemorrhage is described. Massive blood loss and the resultant hypotension was instrumental in reducing the perfusion pressure at the optic nerve head and producing ischemic damage to it.

Acute Disease↗
PubMed1993

Solid tumours of the ovary.

One hundred seventeen solid ovarian tumours, diagnosed histologically during the period between 1971 and 1990, were studied. The overall incidence of solid ovarian tumours was 23.4% of all the ovarian tumours (500 cases) studied. Of 117 solid ovarian tumours 19 (16.2%) were benign and the rest 98 (83.8%) were malignant. Epithelial tumours were the commonest (28.2%) followed by germ cell tumours (22.2%), sex cord stromal tumours (21.4%), metastatic tumours (19.7%) and non-specific tumours (8.5%). The average age (26.8 years) was comparatively low for germ cell tumours otherwise in other groups it ranged between 42 and 45 years. Below 15 years immature teratoma was diagnosed in 4 cases and granulosa cell tumour in 2 cases. Bilateral tumours were seen in 22 cases (23.2%) out of 95 cases observed. Pain and fullness in the pelvic region were observed in 94.9% cases. Varied morphological picture was seen in 6 cases of endometrioid carcinoma. Dysgerminoma constituted 6.8% of solid ovarian tumours. Gliomatosis peritonei was noticed in one case of immature teratoma. Granulosa cell tumour accounted for 11.1% of solid ovarian tumours. Of 23 cases of metastatic tumours, Krukenberg tumour was noticed in 88.9% cases. Diagnostic problems as well as prognostic factors of solid ovarian tumours have been discussed.

Adolescent↗
PubMed1993

GABA B mediated analgesia in tonic pain in monkeys.

The present study was designed to characterise the analgesia produced by the GABA B agonist baclofen in tonic pain in monkeys. The effect of various doses of baclofen was studied on formalin induced pain. Baclofen was injected intraperitoneally 30 min prior to formalin injection in five doses of 2, 4, 6, 8, and 10 mg/kg and the pain was quantified for a period of one hour. Baclofen produced dose related analgesia, 6 mg/kg having maximal effect. The antinociceptive effect of baclofen could be attributed to the effect of baclofen on GABA B receptors producing presynaptic inhibition of primary nociceptive afferents in the dorsal horn of the spinal cord.

Analgesics↗
PubMed1993

Evaluation of radionuclide gastroesophagography as a suitable screening test for detection of gastroesophageal reflux.

Thirty cases of recurrent pulmonary infection and ten control cases underwent radionuclide gastroesophagography endoscopy, histopathology and barium esophagography to evaluate the clinical efficacy of scintigraphic technique in, detection of gastroesophageal reflux. After ingesting 500 micro curie of Tc-Sulphur colloid mixed in milk, patients esophageal activity was monitored using the gamma camera for forty-five minutes continuously. By using histopathology as standard of comparison, the sensitivity and specificity of radionuclide esophagography was 78.54 and 81.25%, respectively. Because of its physiologic nature, low radiation exposure and convenience, radionuclide esophagography is recommended as a suitable screening test for detecting gastroesophageal reflux where available.

Barium Sulfate↗
PubMed1993

WAGR complex.

Explore the source record for details and available documents.

Child, Preschool↗
PubMed1993

A hospital-based study on the use of paramedical personnel for clinical downstaging of cancer cervix.

Two auxiliary nurse midwives (ANMs) were recruited and trained to recognize normal and different types of abnormal cervices. A total of 2102 women were examined by a gynaecologist and ANM independently and their findings were noted. Comparison of their findings showed an overall agreement of 89.6 per cent (Kappa 0.84 with standard error of 0.015 and a significantly large Z value of 55.6). Gross examination of 4679 women attending the Gynaecology OPD revealed normal cervix in 49.6 per cent and suspected lesions or malignant cervix in 3.4 per cent of women. Cytology smears were taken in 3608 women. Adequacy of smears was 97 per cent. Comparing the group clinically diagnosed as highly suspected or malignant to the cytologically diagnosed suspected group (atypical and malignant), clinical examination had a sensitivity of 81.7 per cent and specificity of 97.3 per cent; while comparison of the group clinically diagnosed as abnormal cervix to abnormal cytology (all grades of dysplasia, atypical and malignant cells), the clinical examination had a sensitivity of 92.5 per cent and specificity of 37.4 per cent. It was concluded that paramedical staff (ANMs) can be relied upon to do speculum examination in women in the community and take cytology smears in selected cases.

Allied Health Personnel↗
PubMed1993

Effect of superoxide exposure on albumin permeability of isolated rat glomeruli.

Reactive oxygen radicals generated by mesangial cells or by resident or infiltrating macrophages may contribute to glomerular injury in glomerulonephritis. To determine whether superoxide anions have an effect on the glomerular barrier to macromolecules, we studied the responses of isolated glomeruli after exposure to superoxide generated by xanthine and xanthine oxidase or by activated macrophages. Glomerular volumetric responses to oncotic gradients of bovine serum albumin or an impermeant neutral dextran (mol wt 252 kd0 were used to calculate the albumin reflection coefficient (sigma albumin) and convectional permeability to albumin (1-sigma albumin) of control and superoxide-treated glomeruli. Albumin permeability of control glomeruli was not different from 0 (0.02 +/- 0.01, N = 50). After 10 minutes of exposure of glomeruli to superoxide generated by xanthine oxidase, albumin permeability was increased to 0.06 +/- 0.01 (N = 50). Albumin permeability did not increase further after incubations with xanthine and xanthine oxidase for up to 60 minutes. The increase in albumin permeability was prevented by superoxide dismutase (-0.02 +/- 0.01, N = 48) but was not affected by catalase or by indomethacin pretreatment. Coincubation of glomeruli with activated macrophages also increased albumin permeability to a maximum of 0.80 +/- 0.05 (N = 17). Albumin permeability was not increased by incubation of glomeruli with phorbol myristate acetate alone or with macrophages in the absence of phorbol myristate acetate. The effect of activated macrophages on albumin permeability, like that of superoxide generated chemically, was prevented by superoxide dismutase but not by catalase or indomethacin.(ABSTRACT TRUNCATED AT 250 WORDS)

Albumins↗
PubMed1992

Reversed-phase chromatographic method for specific determination of glutathione in cultured malignant cells.

A chromatographic method for the specific determination of glutathione in malignant cell lines is described. The method is based on the ability of glutathione-S-transferase to specifically and quantitatively conjugate glutathione to 1-chloro-2,4-dinitrobenzene and chromatographic quantitation of the resultant conjugate, dinitrophenyl-S-glutathione, by reversed-phase liquid chromatography. The assay can be performed on 20,000 g supernatants of cell homogenates without acid extraction. 2-Mercaptoethanol, a sulfhydryl compound often used as a thiol-protective agent to preserve enzymatic activities of a number of enzymes, did not interfere with glutathione determination by this method. The dinitrophenyl-S-glutathione isolated from either standard glutathione samples or from cell homogenates was shown to be identical to authentic dinitrophenyl-S-glutathione using mass spectrometry. Recovery of glutathione in standard samples by the current method was identical to that determined using 5,5'-dithiobis(2-nitrobenzoic acid). Exogenous glutathione added to supernatants of cell homogenate in the presence or absence of 2-mercaptoethanol was also completely recovered.

Chromatography, High Pressure Liquid↗
PubMed1992

Gender related differences in the expression and characteristics of glutathione S-transferases of human colon.

In the present study, the expression of glutathione S-transferase (GST) isozymes was compared in human male and female colon tissues. GST isozymes were purified and quantified in five male and five female colon tissue samples. Noticeable differences were observed in the isoelectric focusing profiles (IEF) of the GSTs, from male and female colon tissues. Both male and female colon tissues had three common GST peaks with pI values of 9.2, 6.7 and 4.8. An additional GST peak with a pI value of 6.2 found in all females was not found in males. Based on kinetic, immunological and structural properties, these isozymes were classified into alpha (pI 9.2), mu (pI 6.7 and 6.2) and pi (pI 4.8) classes. Activity of the alpha-class GST in male colon was approx. 2-fold higher than the corresponding isozyme in female colon. The pi-class GST 4.8 was the most predominant GST in both the sexes and its activity with CDNB as substrate was more abundant (about 1.6-fold) in female colon as compared to that in male colon. Significant differences were seen in substrate specificities between male and female colon GST 4.8. Sex related differences were also observed in the inhibition kinetics of GST pi from male and female colon in the presence of hematin. In addition, GST pi isolated from female colon was more thermostable as compared to the corresponding male isozyme. The thermostability of purified GST pi isozyme from males or females was not affected by incubation of the enzyme with either estrogen, testosterone or progesterone.

Amino Acid Sequence↗
PubMed1992

P-glycoprotein expression during tumor progression in the rat liver.

P-Glycoprotein (Pgp) has been shown to mediate multidrug resistance in tumor cell lines. Overexpression of Pgp has been detected in clinical cancer samples of many histological types. The basis and biological significance of such increases in Pgp expression are not well understood. In this study, the expression of Pgp during stepwise progression to rat liver cancer was examined to investigate the possible role of Pgp in carcinogenesis. An immunohistochemical technique was used to detect Pgp at the single-cell level, in a large number of liver nodules, hepatocellular carcinoma, and in distant metastases of the carcinomas. The results showed that distinct changes in Pgp expression occurred during stepwise liver carcinogenesis and that these changes were closely associated with the microscopic anatomy of the lesions. In contrast to gamma-glutamyl transpeptidase and glutathione S-transferase-7.7, whose expression appeared to correlate with the early steps of liver carcinogenesis, Pgp expression was higher in the large hyperplastic nodules and in hepatocellular carcinomas than in the early microscopic lesions. A particularly striking finding was the consistent expression of Pgp in the lung metastases. These findings suggested that Pgp was associated with a more progressed malignant phenotype in liver carcinogenesis.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1992

Mechanistic studies on rhodopsin kinase. Light-dependent phosphorylation of C-terminal peptides of rhodopsin.

The phosphorylation of a synthetic peptide, corresponding to the C-terminal 11 amino acids of bovine rhodopsin (VII, residues 338-348), was studied under different conditions. The peptide was only phosphorylated in the presence of photoactivated rhodopsin. Using the same protocol, 12 other peptides, mapping in the rhodopsin C-terminal, were screened for their effectiveness as substrates for rhodopsin kinase. It was found that the peptides became poorer substrates with increasing length, and the best substrates comprised the most C-terminal 9-12 amino acids as opposed to other parts of the C-terminus. It was noted that the absence of the two-terminal residues Pro347 and Ala348 impaired peptide phosphorylation. The effect of the decay of metarhodopsin II on the phosphorylation of rhodopsin and the peptides was determined, and it was found that the rhodopsin and peptide phosphorylations decayed with half times of approximately 33 min and 28 min, respectively. The sites of phosphorylation on the peptides were determined and in all cases the phosphorylation was found to be predominantly on serine residues. Only the 11-residue peptide (VII, residues 338-348) contained significant threonine phosphorylation, which was about 25% that on serine residues. Cumulatively, the results suggest that Ser343 is the preferred site of phosphorylation in vitro. The reason for the poor substrate effectiveness of the larger peptides was examined by competitive experiments in which it was shown that a poorly phosphorylated larger peptide successfully inhibited the phosphorylation of a 'good' peptide substrate. The studies above support a mechanism for rhodopsin kinase that we have termed the 'kinase-activation hypothesis'. This requires that the kinase exists in an inactive form and is activated only after binding to photoactivated rhodopsin.

Amino Acid Sequence↗
PubMed1992

The relationship of doxorubicin binding to membrane lipids with drug resistance.

Doxorubicin (DOX, Adriamycin) binds with high affinity to cellular membranes inflicting multiple lesions which are believed to be important in DOX-mediated neoplastic cell death. Using fluorescence and radioactive [14-14C-14]DOX assays for DOX, we have measured the partitioning of DOX between the cytosolic and membrane fractions of erythrocytes and of DOX-sensitive (V-79) and -resistant (LZ) Chinese hamster lung fibroblast cells. In both erythrocytes and fibroblasts, a significant fraction of DOX was associated with the membrane fraction. More significantly, the quantity of lipid-bound DOX in the fibroblasts correlated with the cell's susceptibility to DOX. The significance of these findings in the context of existing knowledge about DOX-membrane interactions is discussed.

Animals↗
PubMed1992

Identification of an anion-transport ATPase that catalyzes glutathione conjugate-dependent ATP hydrolysis in canalicular plasma membranes from normal rats and rats with conjugated hyperbilirubinemia (GY mutant).

Rat liver canalicular plasma membranes were found to contain a 37-kDa protein that is immunologically cross-reactive with the dinitrophenyl glutathione-stimulated ATPase previously identified in human tissues. The protein, which was partially purified by affinity chromatography, exhibited ATPase activity dependent on dinitrophenyl glutathione, bilirubin ditaurate, and other dianionic compounds. The localization of this protein in the canalicular membrane and its measured enzymatic activity indicate that it is involved in the transport of glutathione derivatives and other dianionic organic compounds. A rat mutant in which the above transport activities are impaired contained the protein in amounts similar to those in a normal control.

Adenosine Triphosphatases↗