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Biomedical subjects

S Gupta

Publications and source records attributed to S Gupta.

At least 1,171 records · Page 65Linked to original sources
PubMed1991

Independent segregation of glutathione S-transferase and fatty acid ethyl ester synthase from pancreas and other human tissues.

Glutathione S-transferase (GST) isoenzymes of human pancreas were purified, characterized and evaluated for their possible role in the metabolism of ethanol. Human pancreas has at least two GST isoenzymes belonging to the Alpha class (pI 8.8 and 8.1), one belonging to the Mu class (pI 6.4) and one belonging to the Pi class (pI 4.9). During the purification of GSTs from pancreas as well as from heart, liver, lung, brain and muscle, the fatty acid ethyl ester synthase (FAEES) activity was monitored in order to evaluate the role of GSTs in metabolism of ethanol, as suggested in earlier studies. Both t.l.c. and h.p.l.c. were used to identify ethyl oleate in reaction mixtures to monitor FAEES activity. During the purification of GSTs with the use of affinity chromatography on GSH linked to epoxy-activated Sepharose 6B, FAEES and GST activities from each of these tissues segregated independently. Purified GST isoenzymes from these tissues did not exhibit any FAEES activity. Antibodies raised against Pi-class GST, as expected, immunoprecipitated most of the GST activity of brain and heart without precipitating FAEES activity. These results suggest that human GST isoenzymes belonging to the Alpha, Mu and Pi classes do not express FAEES activity. The independent segregation of GST and FAEES activities was further demonstrated by monitoring GST activity during the purification of FAEES from pancreas. It was found that purified FAEES had no GST activity towards 1-chloro-2,4-dinitrobenzene and a number of other electrophilic substrates. Results of these studies demonstrate that FAEES and GSTs are distinct proteins.

Acyltransferases↗
PubMed1991

The anionic conjugates of bilirubin and bile acids stimulate ATP hydrolysis by S-(dinitrophenyl)glutathione ATPase of human erythrocyte.

These studies demonstrate that bilirubin-ditaurate (an analog of bilirubin-diglucuronide), lithocholic acid 3-O-sulfate, and lithocholic acid 3-O-glucuronide, which are believed to be transported from liver into bile through an active transport process stimulate ATP hydrolysis by purified dinitrophenylglutathione ATPase of human erythrocytes. The Km and Vmax values of the enzyme for these substrates are similar to those for dinitrophenylglutathione indicating the transport mechanisms for bilirubin conjugates, and anionic bile acid-conjugates from hepatocytes to bile and transport of GSH-conjugates from erythrocytes may be mediated by similar mechanisms.

Adenosine Triphosphatases↗
PubMed1991

Purification and characterization of an ATPase from human liver which catalyzes ATP hydrolysis in the presence of the conjugates of bilirubin bile acids and glutathione.

An ATPase has been purified from the membrane fraction of human liver which catalyzes ATP in the presence of bilirubin ditaurate, lithocholic acid 3-O-sulfate and lithocholic acid 3-O-glucuronide as well as dinitrophenylglutathione and other glutathione conjugates. Its subunit Mr value (38,000) and immunological properties are similar to dinitrophenylglutathione ATPase of human erythrocytes. Kinetic constants of the enzyme for the conjugates of glutathione, bile acids and bilirubin are comparable indicating that this ATPase may mediate active transport of all these anionic conjugates in liver.

Adenosine Triphosphatases↗
PubMed1991

Potential of community-wide chemotherapy or immunotherapy to control the spread of HIV-1.

Whether zidovudine (3'-azido-3'-deoxythymidine, AZT) should be offered to symptomless individuals infected with human immunodeficiency virus type-1 (HIV-1), in the hope of delaying or even preventing progression to AIDS, has been much debated. The discussion has focused on the efficacy of the drug in delaying progression to disease, the severity of its side-effects, and the likelihood of its prolonged and widespread use resulting in zidovudine-resistant strains of the virus. Little attention has been given to the degree to which treatment reduces the infectiousness of symptomless patients, and to the concomitant implications for the overall transmission rate of HIV-1 in the community. Here we use simple mathematical models to show that community treatment with antiviral drugs or immunotherapies that lengthen the incubation period of AIDS without significantly reducing the infectiousness of treated individuals, can increase the rate at which HIV-1 infection spreads (which is fairly obvious) and can even, under certain circumstances, increase the AIDS-related death rate in the community (which is less obvious).

Acquired Immunodeficiency Syndrome↗
PubMed1991

Generation of stimulated, lymphokine activated T killer (T-LAK) cells from the peripheral blood of normal donors and adult patients with recurrent glioblastoma.

Peripheral blood mononuclear cells (PBM) from normal donors and patients with recurrent glioma were activated initially for 48-72 h with phytohemagglutinin-P (PHA) and recombinant human interleukin-2 (IL-2), and then proliferated in vitro for up to 5 months with IL-2. These cells are termed mitogen-stimulated lymphokine-activated T killer (T-LAK) cells. We measured patterns of T-LAK cell growth, in vitro cytolytic activity on a panel of continuous and primary tumor cells, and the phenotypes of the cells in these cultures. Lymphocyte viability declined dramatically over the first 3-5 days; and then the remaining cells in these cultures began to divide and maintained a constant 30-36 h doubling time for long periods in vitro. Phenotyping revealed that cells in the initial few days of culture were heterogeneous, but became almost totally CD3 T cells after 7-10 days in culture. The T-LAK cells from individual normal donors and cancer patients demonstrated a non-genetically restricted cytolytic ability against a panel of both continuous cell lines and primary autologous and allogeneic glioblastoma cells in vitro. This technique provides a method of generating large numbers of autologous cytolytic T cells with non-restricted anti-tumor activity that can be derived from peripheral blood mononuclear cells.

Adult↗
PubMed1991

Purification and characterization of human muscle glutathione S-transferases: evidence that glutathione S-transferase zeta corresponds to a locus distinct from GST1, GST2, and GST3.

Human muscle glutathione S-transferase isozyme, GST zeta (pI 5.2) has been purified by three different methods using immunoaffinity chromatography, DEAE cellulose chromatography, and isoelectric focusing. GST zeta prepared by any of the three methods does not recognize antibodies raised against the alpha, mu, or pi class glutathione S-transferases of human tissues. GST zeta has a blocked N-terminus and its peptide fingerprints also indicate it to be distinct from the alpha, mu, or pi class isozymes. As compared to GSTs of alpha, mu, and pi classes, GST zeta displays higher activities toward t-stilbene oxide and Leukotriene A4 methyl ester. GST zeta also expresses GSH-peroxidase activity toward hydrogen peroxide. The Kms of GST zeta for CDNB and GSH were comparable to those reported for other human GSTs but its Vmax for CDNB, 7620 mol/mol/min, was found to be considerably higher than that reported for other human GSTs. The kinetics of inhibition of GST zeta by hematin, bile acids, and other inhibitors also indicate that it was distinct from the three classes of GST isozymes. These studies suggest that GST zeta corresponds to a locus distinct from GST1, GST2, and GST3 and probably corresponds to the GST4 locus as suggested previously by Laisney et al. (1984, Human Genet. 68, 221-227). The results of peptide fingerprints and kinetic analysis indicate that as compared to the pi and alpha class isozymes, GST zeta has more structural and functional similarities with the mu class isozymes. Besides GST zeta several other GST isozymes belonging to pi and mu class have also been characterized in muscle. The pi class GST isozymes of muscle have considerable charge heterogeneity among them despite identical N-terminal sequences.

Amino Acid Sequence↗
PubMed1991

Mouse hepatocytes migrate to liver parenchyma and function indefinitely after intrasplenic transplantation.

One approach to gene therapy for hepatic diseases is to remove hepatocytes from an affected individual, genetically alter them in vitro, and reimplant them into a receptive locus. Although returning hepatocytes to the liver itself would be advantageous, the feasibility of this approach has never been evaluated due to the inability to distinguish donor from host hepatocytes. To unambiguously identify transplanted hepatocytes after transplantation, and to better quantitate their number and degree of liver function, two transgenic mouse lines were generated in a C57BL/6 background. The first expresses the Escherichia coli beta-galactosidase gene from the relatively liver-specific human alpha 1-antitrypsin (hAAT) promoter and allows transgenic hepatocytes to be readily identified after 5-bromo-4-chloro-3-indolyl beta-D-galactoside staining; the second produces the hAAT protein under control of the same promoter, which enables hepatocyte survival and maintenance of liver function to be quantitated by measuring the serum levels of hAAT. Hepatocytes isolated from transgenic donors were transplanted into nontransgenic C57BL/6 recipients by intrasplenic injection. Surprisingly, a large fraction of these cells were identified within the liver parenchyma but not the spleen at 2 months after transplantation. The high levels of serum hAAT detected in transplant recipients were stable for greater than 6 months, suggesting that established cells will survive indefinitely. These results have important implications for liver organogenesis and hepatic gene therapy.

Animals↗
PubMed1991

Self-dilatation of cervical oesophagogastric anastomotic stricture: a simple and effective technique.

Anastomotic stricture causing recurrent dysphagia is a serious problem occurring in patients after total oesophagectomy and cervical oesophagogastrostomy. We have developed a technique of self-dilatation of these strictures using a Foley catheter and have effectively managed ten patients. The technique is simple, painless, safe, cost-effective, and, as a domiciliary technique, patient acceptability is high.

Anastomosis, Surgical↗
PubMed1991

Permanent engraftment and function of hepatocytes delivered to the liver: implications for gene therapy and liver repopulation.

To examine the distribution of intrasplenically transplanted hepatocytes, we used HBsAg-producing G7 HBV transgenic hepatocytes or cells labeled with 111In. Most hepatocytes translocated to the liver (55% +/- 7%; mean +/- S.D.); the spleen retained a smaller fraction (15% +/- 3%); and some transplanted cells localized in lungs (3%) or pancreas (1%). Transplanted hepatocytes were rapidly assimilated into the liver lobule. Morphometrical quantitation indicated that the numbers of transplanted hepatocytes in the liver at 48 hr and at 9 mo after transplantation were similar. Serum HBsAg was detected in recipients of the G7 HBV hepatocytes during the 1-yr experiment. These results indicate that a large number of hepatocytes can be reproducibly delivered to the liver by transplantation into the spleen. Transplanted hepatocytes engraft rapidly, assimilate into host liver, maintain normal function and survive permanently. Systems for safe delivery and localization of hepatocytes in the liver represent a critical step toward successfully accomplishing hepatocyte-directed gene therapy and repopulation of the acutely devastated liver.

Animals↗
PubMed1991

Glutathione S-transferase-catalyzed conjugation of 9,10-epoxystearic acid with glutathione.

The possible role of glutathione S-transferases (GST) in detoxification of fatty acid epoxides generated during lipid peroxidation has been evaluated. Present studies showed that cytosolic human glutathione S-transferases belonging to alpha, mu, and pi classes isolated from human liver and lung catalyzed the conjugation of glutathione and 9,10-epoxystearic acid. The product of enzymatic reaction, i.e., conjugate of GSH and epoxystearic acid, was isolated and characterized. The Michaelis constant (Km) values of the alpha, mu, and pi classes of GSTs for 9,10-epoxystearic acid were found to be 0.47, 0.32 and 0.80 mM, respectively, whereas the maximal velocity (V max) values for the alpha, mu, and pi classes of GSTs were found to be 142, 256, and 52 mol/min/mol, respectively. These results indicate that even though 9,10-epoxystearic acid is a substrate for all the three classes of GSTs, the mu class isozymes have maximum activity toward this substrate and may preferentially metabolize fatty acid epoxides more effectively as compared to the other classes of GSTs.

Glutathione↗
PubMed1991

Host dependent modulation of hepatitis delta virus replication in chronic delta hepatitis.

To determine whether host dependent differences modulated hepatitis delta virus replication in chronic delta hepatitis, we tested HDV RNA in homosexual and intravenous drug abuser populations. Overall, the seroprevalence of HDV RNA in the two groups with matching clinical characteristics was 72% (76/106 patient visits). A trend for greater prevalence of HDV RNA was noted at initial presentation in homosexuals (82%) compared to intravenous drug abusers (60%, P less than 0.05) and this trend appeared to be maintained during two years of sequential follow-up. The seroprevalence of co-appearing IgM and IgG anti-HD antibodies was similar in the two groups of patients. However, in HDV RNA positive homosexuals IgG anti-HD antibody was more prevalent, and additionally, assumed concordance with HDV RNA of 92% although the significance of this observation is unclear. The difference in prevalence of HIV in the two groups did not reach statistical significance. Prospective studies are required to confirm differences in HDV replication in various patient groups and to define underlying mechanisms.

Adult↗
PubMed1991

Characterization and histopathological correlation of cytosol proteins of benign and malignant breast tumors.

Significant differences in cytosol protein level exist between normal/benign and cancerous breast tissues. There is a positive correlation between the cytosol protein level and histological grade of carcinoma. Well-differentiated carcinoma have a lower value of cytosol protein than poorly differentiated carcinoma. In slab gel electrophoregrams, the total numbers of bands are almost identical in normal, benign, and malignant conditions. In addition, 37 Kd protein band is consistently present in malignant cases and always absent in normal or benign cases. More extensive biophysical examination of this band may provide further insight into the protein alterations in cancer cells at the molecular level.

Adult↗
PubMed1991

Serum trace elements and Cu/Zn ratio in breast cancer patients.

Serum copper, zinc, and the Cu/Zn ratio were measured in 55 patients with breast disease (20 with benign breast diseases and 35 patients with breast cancer) and 30 controls. The mean serum copper levels were higher in breast cancer than in benign breast diseases (167.3 micrograms/dl vs. 117.6 micrograms/dl) (P less than 0.001) and controls (167.3 micrograms/dl vs. 98.8 micrograms/dl) (P less than 0.001). Patients with advanced breast cancer had higher serum copper levels than did patients with early breast cancer (177.9 micrograms/dl vs. 130.4 micrograms/dl) (P less than 0.001). The mean serum zinc levels were lowered only in patients with advanced breast cancer as compared with controls (88.6 micrograms/dl vs. 115.1 micrograms/dl) (P less than 0.001). Serum zinc levels were not decreased in patients with early breast cancer and benign breast diseases. The Cu/Zn ratio was increased in breast cancer patients (1.91 vs. 0.86) (P less than 0.001) but not in patients with benign breast diseases. The precise mechanisms responsible for the alterations in trace element levels in breast cancer patients are still unclear and require further evaluation. However, the serum copper levels and the Cu/Zn ratio may be used as biochemical markers in these patients.

Adult↗
PubMed1991

Bioavailability and pharmacology of oral idarubicin.

A total of 9 patients entered in a phase I trial who received oral idarubicin daily for 3 days took part in pharmacokinetic studies, and bioavailability studies were performed on 13 additional patients receiving single doses of oral idarubicin alternating with i.v. treatment. The data were best fit by a two-compartment model (distribution and elimination compartments for i.v. drug and absorption and single-phase elimination for oral drug). For different idarubicin doses in the phase I and bioavailability studies, the median values for the terminal half-life of idarubicin varied from 5.6 to 11.6 h. High concentrations of the active metabolite idarubicinol were formed. Idarubicinol was eliminated more slowly than was the parent compound, with median half-lives for different dose levels varying from 8 to 32.7 h. Although most pharmacokinetic parameters were similar in plasma and whole blood, peak concentrations and AUCs in whole blood were about 3-4 times those calculated in plasma for idarubicin and about 1.5-2 times those determined in plasma for idarubicinol, indicating fairly extensive uptake into erythrocytes. Oral bioavailability was determined by comparing oral idarubicin to i.v. drug with respect to the combined idarubicin and idarubicinol plasma AUCs, and it varied from 12%-49% (median, 29%). Bioavailability was essentially the same (30%) when whole-blood values were used. Urinary excretion of the drug was less than 5% of the delivered dose by 96 h. Granulocytopenia correlated with plasma idarubicinol "estimated" clearance and steady-state volume of distribution, with whole-blood idarubicinol AUC, area under the moment curve (AuMC), and "estimated" clearance and volume of distribution, and with whole-blood combined idarubicin and idarubicinol AUCs. This suggests that drug contained in erythrocytes plays a major role in toxicity and that idarubicinol may play a larger role in toxicity than does the parent compound.

Administration, Oral↗