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S D Gupta

Publications and source records attributed to S D Gupta.

At least 55 records · Page 3Linked to original sources
PubMed1993

Characterization of a temperature-sensitive mutant of Salmonella typhimurium defective in apolipoprotein N-acyltransferase.

On screening 440 temperature-sensitive (ts) mutants of Salmonella typhimurium, a mutant strain SE5312 which accumulated apolipoprotein (ALP) at 42 degrees C was identified. In vitro assay of apolipoprotein N-acyltransferase activity indicated that the mutant cell envelope contained reduced activity as compared to the wild-type strain. Transduction with a Mud-P22 mapping set placed the ts mutation to 14-17 min region of the S. typhimurium chromosome. P22 transduction using transposon insertions in this region revealed a linkage of the ts mutation to cobD (6%), nag (8%), and corC68 (99%). The ts phenotype was complemented by a 2.3-kilobase EcoRI subclone derived from lambda-phage 170 of Kohara's bank of Escherichia coli. Restriction enzyme analysis of the cloned DNA revealed that this 2.3-kilobase EcoRI fragment included the copper transport (cutE) gene in E. coli. The mutant strain SE5312 was copper-sensitive at 30 degrees C, and the complementing clone conferred copper resistance and restored the ALP N-acyltransferase activity in the mutant cell. Wild-type strain of S. typhimurium harboring this clone exhibited elevated levels of ALP N-acyltransferase activity. These results suggest that the cloned gene encodes the ALP N-acyltransferase. Upon shift to the non-permissive temperature, the viability of the mutant cells decreased, and the mutant cells assumed anomalous morphology. Temperature-resistant revertants could be readily isolated, and a subset of tr revertants contained no detectable lipoprotein. A lpp::Tn10 derivative of the mutant SE5312 was also temperature-resistant. These observations suggest that ALP N-acyltransferase is essential for the growth and viability of S. typhimurium, and this requirement is decreased in the absence of major outer membrane lipoprotein.

Acylation↗
PubMed1991

Phosphatidylethanolamine is not essential for the N-acylation of apolipoprotein in Escherichia coli.

It has been postulated that the N-acyl fatty acid attached to the amino terminus of the major Escherichia coli lipoprotein is derived from the fatty acid at the 1-position of phosphatidylethanolamine (PtdEtn) (Jackowski, S., and Rock, C.O. (1986) J. Biol. Chem. 261, 11328-11333). To ascertain the role of PtdEtn in the conversion of apolipoprotein to the mature lipoprotein, the lipoprotein from E. coli strain AH930 (pss::kan) containing a null mutation in the phosphatidylserine synthase gene (pss) was studied. Pulse labeling with [35S]methionine for 30 s or 5 min revealed the formation of mature lipoprotein in both wild-type (W3110) and mutant (AH930) cells. [3H]Palmitate-labeled lipoproteins from both the mutant and wild-type cells were found to contain nearly identical amounts of alkali-resistant (amide-linked, 41-42%) and alkali-labile (ester-linked, 58-59%) fatty acids. Edman degradation and dansylation of the immuno-affinity-purified [35S]cysteine-labeled lipoprotein showed that the NH2 terminus of the lipoprotein in the mutant was blocked as in the wild type. In vitro assay of apolipoprotein N-acyltransferase using membranes either from the mutant or the wild-type strain as the source of both the enzyme and the acyl donor revealed that both membranes were equally active in the conversion of [35S]methionine-labeled apolipoprotein to lipoprotein. These data strongly suggest that PtdEtn is not essential for the N-acylation of apolipoprotein to form lipoprotein, and other major phospholipids such as phosphatidylglycerol and cardiolipin can serve as the donor of fatty acid in the N-acylation of apolipoprotein.

Acylation↗
PubMed1991

Identification and subcellular localization of apolipoprotein N-acyltransferase in Escherichia coli.

Apolipoprotein N-acyltransferase, the enzyme catalyzing the conversion of apolipoprotein to mature lipoprotein, was detected by an in vitro assay using [35S]methionine-labeled apolipoprotein as the substrate. Triton X-100 solubilized the enzyme, and was required for its activity. The enzyme showed a broad pH optimum (pH 6.5-7.5). N-Acylation of apolipoprotein with ethanol-washed membranes was dependent on exogenous phospholipids, with phosphatidylethanolamine, phosphatidylglycerol and cardiolipin all showing about 10- to 20-times enhancement of the enzyme activity in the delipidated membranes. Incubation of apolipoprotein with [3H]palmitate-labeled membranes resulted in the incorporation of [3H]palmitate into lipoprotein. The enzyme was found to be enriched in the inner membrane and in the inner membrane/outer membrane mixed fractions of the E. coli cell envelope.

Acyltransferases↗
PubMed1991

Histochemical pattern in alimentary tract duplications of children.

Detailed histological and histochemical studies using PAS, AB-PAS, and high-iron diamine-AB were done on 12 alimentary tract duplication cysts in children. Nine of these were thoracic and three were abdominal in location. A total of 11 cysts (nine thoracic and two abdominal cysts) were lined by gastric mucosa seen in varying stages of maturation. One triloculated cyst had, in addition, small intestinal mucosa and bronchial wall mucosa. One intra-mucosal rectal cyst was lined exclusively with primitive rectal mucosa. The cysts showed a variable pattern of mucin histochemistry. In three cysts, the gastric mucosa showed neutral mucins. In another three cysts, in addition to neutral mucins, focal positivity for sulphomucins was observed in the apical region of the surface epithelial cells. In the remaining five cysts, the gastric mucosa showed neutral mucins along with a variable mixture of sulpho- and sialomucins. A correlation was seen between mucin histochemistry and the age of the patient. Neutral mucins or focal positivity for sulphomucins was seen in patients aged 7 months or more, whereas a mixture of sulpho-, sialo-, and neutral mucins was identified in patients who were 1 month old, or less.

Abdomen↗
PubMed1990

Adult embryonal rhabdomyosarcoma of the vagina complicating pregnancy: a case report and review of the literature.

Embryonal rhabdomyosarcoma of the vagina in adults per se is uncommon and pregnancy complicated by such tumors is extremely rare. We wish to report one case of vaginal embryonal rhabdomyosarcoma, diagnosed at the age of 23 years who was carrying at the time of initial presentation. The problem of management of rhabdomyosarcoma in adults, particularly when they are associated with pregnancy is discussed. We advocate the use of multiagent chemotherapy and pelvic radiotherapy in its overall management.

Adult↗
PubMed1988

The biosynthesis of sulfoquinovosyldiacylglycerol: studies with groundnut (Arachis hypogaea) leaves.

The biosynthetic pathway of sulfoquinovosyldiacylglycerol (SQDG) was investigated using groundnut (Arachis hypogaea) leaf discs and 35S-labeled precursors. [35S]SO4(2-) was actively taken up by the leaf discs and rapidly incorporated into SQDG. After 2 h, 1.5% of the [35S]SO4(2-) added to the incubation medium was taken up, of which 28% was incorporated into SQDG. The methanol-water phases of the lipid extracts of the leaf discs were analyzed for the 35S-labeled intermediates. Up to 2 h of incubation, cysteic acid, 3-sulfopyruvate, 3-sulfolactate, 3-sulfolactaldehyde, and sulfoquinovose (SQ) which have been proposed as intermediates [Davies et al. (1966) Biochem. J. 98, 369-373] were not labeled. Only a negligible amount of radioactivity was observed in these compounds after incubation for 4 h and more. Addition of sodium molybdate inhibited the uptake of [35S]SO4(2-) as well as its incorporation into SQDG by the leaf discs, suggesting that 3'-phosphoadenosine-5'-phosphosulfate may be involved in the biosynthesis of SQDG. Addition of unlabeled cysteic acid to the incubation medium enhanced the uptake of [35S]SO4(2-) but did not affect its incorporation into SQDG. 35S-labeled cysteic acid was taken up by the leaf discs and metabolized to sulfoacetic acid but not incorporated into SQ or SQDG. These results show that cysteic acid is not an intermediate in SQDG biosynthesis. [35S]SQ was taken up by the leaf discs and incorporated into SQDG in a time-dependent manner. [35S]Sulfoquinovosylglycerol was also taken up by the leaf discs but not incorporated into SQDG. It is concluded that SQDG is not biosynthesized by the proposed sulfoglycolytic pathway in higher plants. Though [35S]SQ was converted to SQDG, the rates are much lower compared to [35S]SO4(2-) incorporation, which suggests that a more direct pathway involving sulfonation of a lipid precursor may exist in higher plants.

Arachis↗
PubMed1987

Metabolism of the plant sulfolipid--sulfoquinovosyldiacylglycerol: degradation in animal tissues.

Metabolism of the plant sulfolipid--sulfoquinovosyldiacylglycerol (SQDG)--was studied in animal tissues. In vivo experiments with [35S]SQDG in guinea pigs showed that this lipid is not absorbed intact in the gastrointestinal tract. In these experiments, 3 h after administration of [35S]SQDG, the intestinal mucosa contained 1 to 5% of the radioactivity as SQDG, while the remainder was in a water-soluble form. Analysis of the water-soluble components showed that about 60% of the radioactivity was present as sulfoquinovosylglycerol (SQG) and the remainder was present as free SO4(2-). In the blood, 99% of the radioactivity was present as SO4(2-), SQG was not observed. In liver, only very little radioactivity was observed and appeared to be mainly in the form of SO4(2-). Experiments with everted intestinal sacs of guinea pigs confirmed the formation of SQG, SO4(2-), and, in addition, sulfoquinovosylmonoacylglycerol (SQMG) in this tissue. In vitro experiments with saline extracts of acetone powders of pancreas and intestinal mucosa of guinea pig, sheep, and rat showed that [35S]SQDG was deacylated to SQMG (sulfolipase A activity) and SQG (sulfolipase B activity). It is concluded that animal tissues deacylate SQDG in a stepwise manner to SQG. It is further metabolized to yield free SO4(2-) by cleavage of the C-S bond which appears to be brought about by the intestinal microflora. Sheep pancreatic sulfolipases were characterized. Bile salts, sodium dodecyl sulfate, and Triton X-100 inhibited the pancreatic sulfolipases, while CaCl2 activated them. Substrate competition experiments and investigations on substrate specificity with a partially purified preparation indicated that relatively specific sulfolipase(s) may exist in pancreas. Among the species tested, guinea pig tissues showed the highest sulfolipase A and B activities followed sheep and rat tissues. Pancreatic enzymes were 18 to 60 times more active than intestinal enzymes.

Animals↗
PubMed1987

Endoscopic evaluation of dysphagia in the elderly.

A survey of 100 consecutive endoscopies on elderly patients with suspected obstructive dysphagia is reported. Seventy-eight patients had positive findings and one to three lesions were reported in these cases. Benign stricture of the oesophagus was the commonest finding, and led to active treatment (dilation) in most cases either with Hurst bougies or Eder dilators. Fifteen patients had upper gastro-intestinal malignancy (12 oesophagus, three stomach). All of those with oesophageal carcinoma received some form of active treatment, either in the form of radiotherapy, surgery, dilation or Celestin tube insertion. Six patients with negative endoscopies had diagnoses established by other means and in 14 no cause was identified, but in four of these symptoms settled after endoscopy. The duration of dysphagia was not particularly helpful clinically. Two thirds of 'endoscopically normal' patients had short histories with dysphagia for less than 1 year, as did half of the patients with benign stricture. Most patients who were found to be malignant had experienced dysphagia for only a short time although one patient had a 4-year history! Upper gastro-intestinal endoscopy is a safe and valuable procedure in elderly patients with dysphagia and often leads to positive therapeutic intervention even in quite frail subjects.

Aged↗
PubMed1986

Changes of lipid spectrum in different tissues of Furadan-treated mice.

The effects of multiple intraperitoneal doses of Furadan (0.125 mg/kg, 0.25 mg/kg and 0.50 mg/kg, respectively) for the 2nd week, 4th week and 6th week of treatment on the concentrations of total lipid and its different fractions and lipase activity in mice were studied. The following were measured in liver, kidney, brain and serum; total lipid, cholesterol (total and free), phospholipid (total and its fractions--lecithin, lysolecithin, phosphatidyl ethanolamine and lysophosphatidylethanolamine), triglyceride, free fatty acid. Lipase activity was measured in liver and serum. Furadan caused biochemical disorders of the tissues. All the aforesaid lipid fractions (except free fatty acid) are elevated significantly in liver, kidney and serum of Furadan-treated mice. Free fatty acid increased significantly in serum and remain constant in other tissues of pesticide-treated mice. All the lipid fractions except phospholipid and its fractions remained constant in brain of treated mice; total phospholipid and its fractions decreased significantly in brain of treated mice. Lipase activity decreased significantly in liver and serum of treated mice. Such disorders of lipid levels in the aforesaid tissues might be associated with CNS depressant action and structural and functional toxicity of other tissues induced by Furadan.

Animals↗
PubMed1985

Lipid spectrum in different tissues of MT81 toxin-treated mice.

The effects of different intraperitoneal doses of MT81 (2.5 mg/kg, 5.0 mg/kg and 7.5 mg/kg, respectively) for a 2-week, 4-week and 6-week treatment on concentration of total lipid and its different fractions of liver, brain, kidney, testis and serum in mice were studied. The following were measured: total lipid, free and total cholesterol, total phospholipid and its fractions (lecithin, lysolecithin, phosphotidylethanolamine and lysophosphotidylethanolamine), triglyceride, free fatty acid; lipase activity was also measured in serum, liver, and testis. Ascorbic acid content of testis was also measured. This mycotoxin (MT81) caused biochemical disorders of the tissues. Total cholesterol, free cholesterol, total phospholipid and its fractions, triglycerides and total lipids were elevated significantly in liver, serum, kidney and testis of toxin-treated animals. Free fatty acid increased significantly at a later stage in serum and remained constant in other tissues of toxin-treated mice. All the lipid fractions except total phospholipid and its fractions remained constant in brain of treated animals; total phospholipid and its fractions decreased significantly in brain of toxin-treated mice. Lipase activity decreased significantly in serum, liver and testis of treated mice. Ascorbic acid content of testis of treated animals increased significantly. Such disorders of lipid concentrations in the aforesaid tissues might be associated with the CNS depressant action and structural and functional toxicity of other tissues induced by the MT81 toxin.

Animals↗
PubMed1985

Routine chest radiography in the elderly.

Routine chest radiography is common practice in geriatric admission units. The cumulative cost of this unproven procedure is very high, and the authors challenge the need to carry out the investigation in all cases. A prospective survey of 1000 consecutive admissions to an acute geriatric ward showed that 35-50% had little or no clinical indication for chest X-ray examination, and that omitting the investigation in these patients would not have resulted in 'missed' significant chest conditions. Considerable savings to the service would accrue if radiology was restricted to those patients with a positive indication for the investigation.

Aged↗
PubMed1985

The symptomatic post-surgical stomach--an endoscopic review.

100 consecutive endoscopies in elderly patients referred with symptoms after previous gastric surgery are reviewed. 57% showed positive findings, and the procedure was found particularly useful in making definitive diagnoses in patients presenting with dyspepsia and upper gastro-intestinal bleeding. The incidence of gastric carcinoma was low, and the findings did not support routine repeated endoscopies in elderly patients.

Aged↗