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Biomedical subjects

N Ghosh

Publications and source records attributed to N Ghosh.

At least 73 records · Page 4Linked to original sources
PubMed1990

Effect of chromium administration on glutathione cycle of rat intestinal epithelial cells.

Acute oral administration of K2Cr2O7 (1500 mg/kg body wt/day) for 3 days to rats led to the decrease in activities of glucose-6-phosphate dehydrogenase, glutathione peroxidase, glutathione reductase, glutathione-S-transferase, superoxide dismutase and catalase of intestinal epithelial cells. Glutathione and total thiol contents were decreased while lipid peroxidation was increased markedly using the whole homogenate of the intestinal epithelial cells. Chronic oral administration of K2Cr2O7 (300 mg/kg body wt/day) for 30 days to rats on the other hand, led to marked increase in superoxide dismutase and glutathione peroxidase activities with no appreciable change in glucose-6-phosphate dehydrogenase, glutathione reductase and catalase activities. However, glutathione-S-transferase activity was decreased significantly. In the whole homogenate of rat intestine, glutathione and total thiol contents were decreased not so significantly but there was a slight enhancement in lipid peroxidation value.

Animals↗
PubMed1990

Phosphatidylcholine stimulates the activity of UDP-Gal beta 1-4 galactosyltransferase in normal human kidney proximal tumour cells.

Effects of various lipid components of low density lipoproteins (LDL) and serine on the regulation of UDP-Gal-beta 1-4-galactosyltransferase (GalT-2) activity have been investigated in normal proximal tubular (PT) cells. Addition of exogenous serine (0.1-0.75 mM), cholesterol (0-200 micrograms/ml medium), linoleic acid and oleic acid (0.1-0.75 mM) for 4 hr at 37 degrees C did not suppress the activity of GalT-2 in PT cells. Similarly, incubation of cells with glucosylceramide and lactosylceramide (25-50 micrograms/ml medium) did not alter GalT-2 activity in cells as compared to control. In contrast, palmitic acid (0-0.75 mM), phosphatidylethanolamine and sphingomyelin (0-200 micrograms/ml) stimulated GalT-2 activity by 20-36% as compared to control. Incubation of PT cells with D-alpha-dipalmitoyl phosphatidylcholine (0-200 micrograms/ml medium) also stimulated the activity of GalT-2, maximum stimulation (200%) occurring with 25 micrograms phosphatidylcholine/ml medium. However, at a higher concentration (200 micrograms/ml), the stimulation of the activity of GalT-2 was in the order of 27% compared to control. Dioleylphosphatidylcholine did not alter GalT-2 activity in PT cells. Thus, it is concluded that (i) various lipid components, sphingosine and serine present in LDL are not involved in the LDL-mediated suppression of GalT-2 activity in normal PT cells, and (ii) stringent structural requirements in the phosphatidylcholine molecule are necessary to exert a time and concentration dependent stimulation of GalT-2 activity.

Cells, Cultured↗
PubMed1990

C-reactive protein (CRP) in haemolymph of a mollusc, Achatina fulica Bowdich.

C-reactive protein (CRP) was found to be one of the major components of the haemolymph of A. fulica with a normal level of approximately 2 mg CRP/ml haemolymph. Immunological cross-reactivity was found between CRP from A. fulica, a mollusc and Limulus polyphemus, an arthropod. The present finding demonstrates the evolutionary significance of C-reactive protein.

Animals↗
PubMed1989

Neutral sphingomyelinase from human urine. Purification and preparation of monospecific antibodies.

A neutral sphingomyelinase which cleaves phosphorylcholine from sphingomyelin at a pH optima of 7.4 was purified 440-fold to apparent homogeneity from normal human urine concentrate employing Sephadex G-75 column chromatography, preparative isoelectric focusing, and sphingosylphospholcholine CH-Sepharose column chromatography. The enzyme is composed of a single polypeptide whose apparent molecular weight is 92,000. Analytical isoelectric focusing revealed that the pI of this enzyme is 6.5. Purified neutral sphingomyelinase was devoid of beta-galactosidase and beta-N-acetylglucosaminidase activity originally present in the urine concentrate. The purified neutral sphingomyelinase (N-SMase) had low levels of phospholipase A1 and A2 activity when phosphatidylcholine was used as a substrate and detergents were included in the assay mixture. However, it had no phospholipase activity toward phosphatidylglycerol and sphingomyelin at pH 4.5 irrespective of the presence or absence of detergents. Monospecific polyclonal antibodies raised against N-SMase immunoprecipitated approximately 70% of N-SMase activity from urine, human kidney proximal tubular cells, and partially purified membrane-bound N-SMase from these cells. Western immunoblot assays revealed that the monospecific polyclonal antibody against urinary N-SMase recognized both the urinary N-SMase and the membrane-bound N-SMase. Because this enzyme is distinct biochemically and immunologically as compared to acid sphingomyelinase (EC 3.1.4.12), we would like to assign it an enzyme catalog number of EC 3.1.4.13. The availability of N-SMase and corresponding antibody will be useful in studying various aspects of this enzyme in biological systems.

Acetylglucosaminidase↗
PubMed1989

Uptake of cadmium by isolated human red blood cells.

Uptake of Cd by human RBC in vitro was studied. The uptake was found to be biphasic with a rapid initial phase followed by a slower second phase which was still increasing at the time of the last experiment (60 min). Both the phases were found to be independent of metabolically derived energy and unaffected by zinc in the incubation medium.

Adult↗
PubMed1988

Regulation of glycosphingolipid glycosyltransferase by low density lipoprotein receptors in cultured human proximal tubular cells.

We have shown previously that low density lipoproteins (LDL) suppressed the synthesis of lactosylceramide in normal human proximal tubular cells, but stimulated such synthesis in proximal tubular cells from LDL receptor negative subjects (Chatterjee, S., Clarke, K., and Kwiterovich, P.O., Jr. (1986) J. Biol. Chem. 261, 13474-13479). To understand the mechanism(s) of this effect of LDL, we have studied here the effects of LDL on the activity of UDP-GalCer:beta-galactosyltransferase (GalT-2). Maximum suppression (70-80%) of the activity of GalT-2 in normal proximal tubular cells at 37 degrees C occurred at a LDL concentration of 25 micrograms/ml medium. Such suppression was not observed either when the cells were incubated with LDL at 4 degrees C, or when the cells were preincubated with leupeptin, followed by incubation with LDL at 37 degrees C. High density lipoproteins and fetuin did not suppress the activity of GalT-2 in normal proximal tubular cells. In contrast LDL modified by reductive methylation (M-LDL, 100 micrograms/ml) stimulated the activity of GalT-2, approximately 3-fold. The effects of LDL and M-LDL were not related to their glycosphingolipid content. Much less suppression and stimulation of the activity of GalT-2 in proximal tubular cells by LDL and M-LDL, respectively, was found in normal human skin fibroblasts, Chinese hamster ovary cells, and bovine smooth muscle cells, suggesting that the LDL-mediated effect may be tissue-specific. In cells grown to very high density, the activity of the LDL receptor is decreased, and there was less suppression of GalT-2 activity by LDL. In normal proximal tubular cells, LDL stimulated the activity of UDP-Gal:LacCer, alpha-galactosyltransferase activity, UDP-Gal:LcOse3Cer, beta-galactosyltransferase, and CMP-NeuAc:LacCer,alpha-sialyltransferase activity but did not alter the activity of sulfotransferase. In conclusion, LDL that entered the normal proximal tubular cells via the LDL receptor-mediated pathway decreased GalT-2 activity, an effect that was dependent upon the binding, internalization, and degradation of receptor-bound LDL. In contrast LDL that entered normal or LDL receptor-negative proximal tubular cells via an LDL receptor-independent pathway failed to suppress GalT-2 activity, and led to a stimulation of LacCer synthesis.

Cell Count↗
PubMed1988

Prognostic value of squamous cell carcinoma antigen in patients with uterine cervical carcinoma.

Squamous cell carcinoma antigen (SCC Ag) was estimated in 30 controls, in 16 patients with benign lesions of the uterine cervix, and in 51 patients with uterine cervical carcinoma. The rate of positivity of the antigen among the cancer patients was 87% (N = 49). SCC Ag estimations were of no diagnostic value, since 37% of patients with benign lesions had elevated levels compared to controls. SCC Ag was highly correlated to histologic subtype. The highest values were obtained in keratinizing tumors, followed by large cell nonkeratinizing and small cell nonkeratinizing types. Moreover, elevation of SCC Ag was statistically significant (p less than 0.001) among all the three histologic subtypes compared to controls. However, SCC Ag levels were not consistently correlated to the stage of the disease. Patients with pretherapeutic SCC Ag levels above 30 ng/ml had a faster recurrence rate and shorter survival than those who exhibited antigen values below 2.0 ng/ml. From our results, it is suggested that SCC Ag has limited use as a parameter for early diagnosis of cervical carcinoma, but it seems to reflect advancement of the disease. These findings indicate that SCC Ag elevation may prove to be a valuable marker in predicting subclinical disease.

Antigens, Neoplasm↗
PubMed1987

Prognosis in breast carcinoma utilizing plasma carcinoembryonic antigen and histologic characteristics of the primary tumor.

Plasma carcinoembryonic antigen (CEA) concentrations in 128 patients with breast cancer were measured preoperatively. The data were related to the histologic features of the primary breast carcinoma and to the clinical follow-up data. Analysis of the plasma CEA values did not show a significant correlation with the histologic type and the histologic and nuclear grade of the primary tumor (n = 73) as well as to the presence or absence of keratin, necrosis, desmoplasia, tubule formation and mucin production. Furthermore, the results indicated that high CEA values (more than 10 ng/ml) may be associated with distant metastasis and not with the metastatic spread to lymph nodes. High CEA levels were also associated with reduced survival of the patients. This study confirms our previous report suggesting that high CEA levels are correlated with tumors of endodermal origin, whereas the CEA levels were within the normal range in the tumors of ectodermal origin. In agreement with other studies, however, it was found that the predictive value of plasma CEA concentrations in general is weak, so that the use of CEA measurement for prognosis is of limited value.

Breast Neoplasms↗
PubMed1987

Induction of hepatic mitochondrial alpha-glycerophosphate dehydrogenase by L-triiodothyronine in Singi fish (Heteropneustes fossilis Bloch).

A single injection of L-triiodothyronine (T3) in different doses (0.25, 0.5, 5, 20 and 50 micrograms/g) increased the hepatic mitochondrial cytochrome-linked alpha-glycerophosphate dehydrogenase (alpha-GPD) activity and mitochondrial protein content of Singi fish, as observed on the 3rd day. A non-linear dose-response relationship with respect to enzyme activity was observed with different doses of T3. A low dose of 0.1 micrograms of T3 per g failed to cause any change in alpha-GPD activity and mitochondrial protein content of the liver. The enhancement of alpha-GPD activity over the control level with a low and a high dose of T3, viz., 0.5 and 5 micrograms/g, was followed from the 1st to the 7th day, when it was found that enzyme activity reached the maximum level on the 3rd day and then gradually declined to the control value on the 7th day. The percentage increase in enzyme activity with 5 micrograms/g was higher than that with 0.5 microgram/g from the 2nd to 5th day. Compared to the control, these two doses of T3 caused an increase in alpha-GPD activity from the 1st to the 6th day. Cycloheximide inhibited the T3-induced increase in alpha-GPD activity, mitochondrial and total protein content of liver. Immersion of Singi fishes in thiourea-containing (1 mg/ml) medium for 30 days showed a fall in hepatic alpha-GPD activity in comparison to the euthyroid control. A single injection of T3 (0.5 microgram/g) to the hypothyroid fish recovered alpha-GPD activity to more than the euthyroid control level. An increase in mitochondrial protein content in the T3-injected hypothyroid fish has been observed. DNA content of the fish liver remained unchanged in every experimental condition. The results thus showed the significant responsiveness of the fish liver to thyroid hormone.

Animals↗
PubMed1980

Foetus compressus.

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Abortion, Missed↗
PubMed1979

An investigation of the conformational properties of ribosomes using N-ethylmaleimide as a probe.

The reactivity of ribosomal proteins towards N-ethylmaleimide has been examined in a variety of ribosome and ribosomal subunit preparations from Escherichia coli. The data show that samples which would be regarded as equivalent operationally can differ significantly in conformation, as judged by reactivity, depending on the method of preparation. The washing of ribosomes with high concentrations of salt has a particularly dramatic effect on protein reactivity. The implications of these results for our understanding of ribosome conformation and for the further study of conformation by chemical reactivity are discussed.

Centrifugation, Density Gradient↗