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Biomedical subjects

S Gupta

Publications and source records attributed to S Gupta.

At least 1,027 records · Page 57Linked to original sources
PubMed1994

Nicotine metabolic profile in man: comparison of cigarette smoking and transdermal nicotine.

The objectives of this study were to 1) quantitatively assess human exposure to various metabolites of nicotine, 2) examine the influence of inhalation vs. transdermal administration on the patterns of nicotine metabolism, and 3) assess the extent of recovery of nicotine as various metabolites in people whose systemic intake of nicotine has been measured. Twelve smokers were studied while smoking cigarettes and while receiving transdermal nicotine. Urinary excretion of nicotine and eight of its metabolites was measured under steady state conditions. The systemic intake of nicotine in these subjects was determined using plasma concentrations and intravenous clearance data, so the percentage of their daily dose of nicotine excreted as various metabolites could be computed. The major findings of the study are as follows: 1) a high percentage (averaging 88%) of a systemic dose of nicotine can be accounted for by measurement of nicotine and its metabolites; 2) the pattern of metabolism is generally similar when nicotine is inhaled or absorbed transdermally; 3) while there is considerable interindividual variability in the pattern of metabolism, the pattern is consistent for an individual; and 4) within individuals, the extent of conjugation of nicotine and cotinine is highly correlated, but neither is correlated with the extent of conjugation of 3'-hydroxycotinine. This suggests that similar enzymes are involved in the conjugation of nicotine and cotinine, and that a different enzyme may be involved in the conjugation of 3'-hydroxycotinine.

Administration, Cutaneous↗
PubMed1994

Plasma selenium level in cancer patients.

Selenium has been shown to be a cancer preventive agent. A few studies have shown that increased selenium level is associated with decreased cancer incidence and decreased cancer mortality. The present study was carried out to find out the relationship of selenium level with site, extent of disease, recurrence of disease, histopathological diagnosis, anaemia and serum protein level of cancer patients. Plasma selenium level were studied in 100 patients and mean selenium level of 75.35 ng/ml in cancer patients was significantly less than control values (116.99 ng/ml) in normal healthy individuals (P < 0.003). The strongest association of plasma selenium level and cancer was found in cancer breast (70.50 ng/ml) and gastrointestinal tract (73.05 ng/ml) cancer. Selenium level decreased with the progress of disease and recurrence of disease. No significant association between histopathological diagnosis and selenium level was observed. Anaemia and hypoproteinemia was also not found to be related with selenium level.

Adult↗
PubMed1993

Evidence for the existence of hyaluronectin-binding proteins in the plasma membranes.

This report documents for the first time the existence of specific binding proteins for hyaluronic acid binding protein (hyaluronectin) in the plasma membranes of normal and transformed cells. Firstly, we showed the specific binding of hyaluronic acid binding protein to the cell surface of normal rat heart fibroblasts (NRHF) by saturation and competition methods using 125I-labeled hyaluronic acid binding protein and calculated the binding dissociation constant (0.43 x 10(-13) M). In order to identify hyaluronectin-binding protein on the cell surface, plasma membranes isolated from rat brain, liver and fibrosarcoma were separated by SDS-PAGE and transferred to nitrocellulose paper by electroblotting. Incubation of the transferred membrane proteins with 125I-labeled hyaluronectin in the presence of non-ionic as well as ionic detergents revealed two prominent bands of approximate molecular mass of 37 kDa and 40 kDa in brain, liver and fibrosarcoma. The specificity of the binding [125I]hyaluronectin to 37-kDa and 40-kDa membrane proteins was further confirmed, as the intensity of the bands was reduced in the presence of a 20-fold excess of unlabeled hyaluronectin. We discuss our observations on hyaluronectin-binding membrane proteins in the context of hyaluronectin-mediated cellular functions.

Animals↗
PubMed1993

Left ventricular diastolic function in end-stage renal disease and the impact of hemodialysis.

Twenty-one patients (17 men and 4 women, aged 20 to 40 years) with end-stage renal disease (creatinine clearance persistently < 5 ml/min for > 3 months) were evaluated for left ventricular (LV) diastolic function by Doppler echocardiography before and after hemodialysis. Fifteen patients were on maintenance hemodialysis (group A) and 6 were studied before and after their first hemodialysis (group B). The following indexes of LV diastolic function were studied: (1) isovolumic relaxation time; and (2) Doppler indexes from mitral inflow signal--peak early velocity, peak late velocity (atrial), deceleration of early filling phase, and deceleration time of early filling phase. LV systolic function in groups A and B (LV ejection fraction 68 +/- 6 and 77 +/- 5%, fractional shortening 0.39 +/- 0.06 and 0.46 +/- 0.05%) was normal and did not change after hemodialysis. Group A had a prolonged isovolumic relaxation time of 80 +/- 22 ms, which decreased to 57 +/- 14 ms (p < 0.005). Deceleration time decreased from 248 +/- 58 to 184 +/- 38 ms (p < 0.00005) and the deceleration slope increased from 4.3 +/- 1.8 to 5.1 +/- 1.6 m/s2 (p < 0.005) after hemodialysis. In group B, isovolumic relaxation time decreased from 87 +/- 21 to 73 +/- 15 ms (p < 0.05), deceleration time decreased from 256 +/- 43 to 185 +/- 34 ms (p < 0.05), and deceleration slope increased from 3.5 +/- 0.8 to 4.2 +/- 1.1 m/s2 (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Paracatalytic self-inactivation of fructose-1,6-bisphosphate aldolase. Structure of the crosslink formed at the active site.

Oxidation of enzyme-substrate carbanion intermediates by extrinsic oxidants may result in irreversible paracatalytic inactivation of certain enzymes. In paracatalytically modified fructose-1,6-bisphosphate aldolase from rabbit muscle the polypeptide chain had been found to be crosslinked at active-site Lys229 (Schiff base forming with substrate) and Lys146 by a phosphorylated three-carbon moiety [Lubini, D. G. E. and Christen, P. (1979) Proc. Natl Acad. Sci. USA 76, 2527-2531]. In the present study, the structure of this crosslink was elucidated by instrumental analysis. Aldolase was paracatalytically modified in the presence of fructose 1,6-bisphosphate and hexacyanoferrate(III). The completely inactivated enzyme was digested with pronase. The crosslinked peptide was isolated by gel filtration and reverse-phase HPLC. Mass spectroscopy, 1H- and 13C-NMR showed that a derivative of dihydroxyacetone phosphate forms an amidine with the epsilon-amino groups of the two lysine residues: [formula: see text]

Amino Acids↗
PubMed1993

Cloning and characterization of complementary DNA encoding the eukaryotic initiation factor 2-associated 67-kDa protein (p67).

The eukaryotic initiation factor 2 (eIF-2)-associated 67-kDa glycoprotein (p67) protects eIF-2 alpha-subunit from inhibitory phosphorylation by eIF-2 kinases, such as heme-regulated inhibitor and double-stranded RNA-activated inhibitor. This promotes protein synthesis in the presence of eIF-2 kinases present in animal cells (Ray, M. K., Datta, B., Chakraborty, A., Chattopadhyay, A., Meza-Keuthen, S., and Gupta, N. K. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 539-543). In this study, the primary structure of rat p67 is determined by cDNA cloning. Based on the partial amino acid sequences of overlapping tryptic and cyanogen bromide cleaved fragments, degenerate oligonucleotides were synthesized and used as primers for the polymerase chain reaction to amplify the corresponding p67 cDNA fragment from rat liver first strand cDNA. The amplified DNA was then used as a probe to screen a rat tumor hepatoma (KRC-7) cDNA library, and a positive clone covering the entire coding region was obtained. From the cDNA sequence, an open reading frame that encodes p67 as a 480-amino acid protein with a molecular mass of 53 kilodaltons was predicted for the unglycosylated protein. The cloned cDNA was further characterized by in vitro transcription-coupled translation in micrococcal nuclease-treated reticulocyte lysate. The translated product migrated similarly to p67 in SDS-polyacrylamide gel electrophoresis and was precipitated with antibodies against p67. Northern blot analysis of rat liver poly(A)+ RNA showed a single size class (approximately 2 kilobases) of mRNA. The deduced amino acid sequence of the protein showed a highly charged N-terminal region composed of two basic polylysine blocks and an acidic aspartic acid block. The protein also exhibits significant sequence identity in the N-terminal region with human eIF-2 beta-subunit.

Amino Acid Sequence↗
PubMed1993

Sequence of a newly identified Mycobacterium tuberculosis gene encoding a protein with sequence homology to virulence-regulating proteins.

Analysis of the nucleotide sequence of a gene cloned from a Mycobacterium tuberculosis H37Rv genomic library predicted a 339-amino-acid protein with an M(r) of 37,656. The protein exhibited significant homology with the Cfad, FapR and Rns proteins from different enterotoxigenic strains of Escherichia coli, VirF protein of Shigella and VirFy protein of Yersinia, all of which regulate virulence-associated genes.

Amino Acid Sequence↗
PubMed1993

Transactivation of gene expression by Myc is inhibited by mutation at the phosphorylation sites Thr-58 and Ser-62.

The product of the human c-myc protooncogene (Myc) is a sequence-specific DNA binding protein. Here, we demonstrate that the placement of the specific Myc DNA binding site CACGTG upstream of a luciferase reporter gene conferred Myc-stimulated expression that was inhibited by the overexpression of the basic-helix-loop-helix/leucine zipper protein Max. It was observed that Myc was phosphorylated in vivo within the NH2-terminal domain at Thr-58 and Ser-62. Replacement of these phosphorylation sites with Ala residues caused a marked decrease in Myc-stimulated reporter gene expression. In contrast, the replacement of Thr-58 or Ser-62 with an acidic residue (Glu) caused only a small inhibition of transactivation. Together, these data demonstrate that the NH2-terminal phosphorylation sites Thr-58 and Ser-62 are required for high levels of transactivation of gene expression by Myc.

Amino Acid Sequence↗
PubMed1993

Chondromyxoid fibroma: a fine-needle aspiration diagnosis.

A 25-yr-old female presented with a slowly progressive swelling, occurring over an 8-yr period, in the right lower leg. The swelling was tender and fixed to the underlying bone. Clinical and radiological diagnosis was giant cell tumor (GCT) of the bone. Aspiration cytology smears were cellular showing an admixture of chondroid, stellate, and fibrocytic cells against a chondroid background. On cytomorphology, a diagnosis of chondromyxoid fibroma (CMF) was made. It was confirmed on histologic examination.

Adult↗
PubMed1993

Sonourethrography in the evaluation of anterior urethral strictures: correlation with radiographic urethrography.

A total of 30 patients with suspected urethral strictures underwent sonographic and roentgenographic urethrograms. Two patients showed a normal anterior urethra in the sonourethrogram; 29 strictures were diagnosed in the remaining 28 patients, 1 patient showing strictures at two different sites. Sonourethrography was an accurate predictor of stricture length, retrograde urethrography underestimating the stricture length in most of the cases. Periurethral structures, including the urethral wall, corpus spongiosum, corpora cavernosa, bulb, and external urinary sphincter, were seen clearly with sonourethrography. Periurethral fibrosis was seen in 16 patients and graded as mild (n = 5), moderate (n = 2) or severe (n = 9), depending on the depth of involvement of the corpus spongiosum. Sonourethrography was unsatisfactory in the evaluation of membranous strictures, failing to visualize the proximal limit of the stricture.

Adult↗
PubMed1993

Serum and tissue trace elements in colorectal cancer.

Serum copper, zinc, and Cu/Zn ratio were measured using atomic absorption spectrophotometry in 30 patients with colorectal cancer and compared with 30 healthy control subjects. In the patients with colorectal cancer, the tissue copper and zinc levels were also measured in paired histologically normal and malignant colorectal tissue samples obtained at surgery. The mean serum copper levels were higher in patients with colorectal cancer (165.99 vs. 98.84 micrograms/dl) (P < 0.001). The mean serum zinc levels were lowered only in advanced (Dukes stages C and D) colorectal cancer compared to controls (89.94 vs. 115.08 mu/dl) (P < 0.001). However, the Cu/Zn ratio progressively increased with the advancing stage of malignancy (1.86 vs. 0.86) (P < 0.001). The cancerous colorectal tissue showed a higher concentration of both copper (2.78 vs. 1.79 micrograms/g) (P < 0.001) and zinc (27.16 vs. 18.98 micrograms/g) (P < 0.01) compared to non-cancerous colorectal tissue. The exact mechanism responsible for the alterations in trace element levels in patients with colorectal cancer is largely unclear and requires further evaluation. However, the serum copper level and the Cu/Zn ratio are of value in estimating the extent of the carcinoma as well as in determining the prognosis of these patients.

Adult↗
PubMed1993

Problems with the "dural tail" sign.

Prominent enhancement of the dura mater, the "dural tail" adjacent to a peripherally located mass on gadolinium-enhanced MRI has been described as being characteristic of meningiomas. We present a cerebral glioma showing the classical "dural tail".

Brain↗