Search PubMed⌕ Search

Biomedical subjects

S K Saha

Publications and source records attributed to S K Saha.

At least 73 records · Page 4Linked to original sources
PubMed1994

Determination of the concentrations of oligosaccharides, complex type carbohydrates, and glycoproteins using the phenol-sulfuric acid method.

The concentrations of methyl glycosides, oligosaccharides, glycopeptides, and glycoproteins can be accurately determined by using calibration curves composed of the appropriate monosaccharide(s) obtained with a modified version of the colorimetric phenol-sulfuric acid method. Calibration curves of micrograms sugar vs. 490 nm for Man, Glc, or Gal are shown to provide reliable determinations (typically +/- 3-4%) of corresponding methyl glycosides and linear and branched-chain oligosaccharides containing the corresponding reactive hexose residue. For complex oligosaccharides containing a known mixture of reactive hexose units, the appropriate mixture of monosaccharides are shown to provide equally accurate calibration curves for concentration determinations. In the case of the soybean agglutinin, which is a tetramer possessing one Man9 oligomannose-type chain per subunit, the protein concentration was determined from the Man calibration curve which agreed with that obtained from the molar extinction coefficient of the protein.

Carbohydrate Conformation↗
PubMed1994

Lipid interference with fluorometric assay of DNA in adipose tissues under various conditions.

Interference by lipids with fluorometric assay of DNA in adipose tissues using Hoechst 33258 was investigated. Mixed glycerides shifted the emission maximum of standard DNA and induced a dose-dependent increase in fluorescence intensity. Glycerides in the samples containing a known concentration of DNA yielded erroneously higher DNA concentrations. The DNA concentrations obtained from acetone-defatted white and brown adipose tissues (WAT and BAT) were lower than those of non-defatted ones, while DNA content did not differ in low lipid-containing skeletal muscle between defatted and non-defatted samples, indicating that large amounts of lipids interfere with DNA measurement using Hoechst 33258 and that acetone defatting is a simple method to avoid this interference. Using this defatting method, the cellularity of WAT and BAT was estimated in rats under various experimental conditions. Cold-acclimation and repetitive immobilization stress decreased the body weight gain and the epididymal WAT weight. Sucrose overfeeding increased WAT weight but not body weight. These treatments of 4 weeks' duration did not induce any significant difference in WAT cell number from controls, while cold-acclimation increased the tissue cell number as well as the BAT weight.

Acetone↗
PubMed1994

Fatal sepsis due to Pseudomonas cepacia.

Pseudomonas cepacia is known as an opportunistic pathogen in the patients with altered host defence. We report a case of hospital-acquired fatal sepsis due to P. cepacia in a child with no known defect in immune system. Virulence of the organism was indicated by the high magnitude of septicaemia. The organism was successfully eliminated by ceftriaxone but the patient died of renal failure.

Bacteremia↗
PubMed1992

The E3-11.6K protein of adenovirus is an Asn-glycosylated integral membrane protein that localizes to the nuclear membrane.

The 11,600 MW (101 amino acids; 11.6K) protein of adenovirus 2 (Ad2) is a protein of unknown function which is synthesized in low amounts during early stages of infection but in very high amounts at late stages. The 11.6K protein migrates as three major groupings of diffuse bands of ca. 14K, 21K, and 31K on SDS-PAGE, indicating that 11.6K undergoes post-translational modification. We show here that 11.6K is Asn-glycosylated with complex (endo H-resistant) oligosaccharides and that 11.6K is an integral membrane protein. Immunofluorescence indicated that 11.6K initially is associated with the endoplasmic reticulum and Golgi apparatus and that it ultimately localizes to the nuclear membrane. The 11.6K protein is predicted to have a single signal-anchor sequence at residues 41-62 and only one potential Asn-linked glycosylation site at residue 14; thus, 11.6K must be oriented in the membranes with its NH2-terminus in the lumen and its COOH-terminus in the cytoplasm. The signal-anchor and glycosylation features of 11.6K are preserved in Ad2 and Ad5 (group C), and in Ad3 and Ad7 (group B), but the sequence of 11.6K is more diverged among these serotypes than is the sequence of most other adenovirus proteins.

Adenovirus E3 Proteins↗
PubMed1992

The 11,600-MW protein encoded by region E3 of adenovirus is expressed early but is greatly amplified at late stages of infection.

We have reported that an 11,600-MW (11.6K) protein is coded by region E3 of adenovirus. We have now prepared two new antipeptide antisera that have allowed us to characterize this protein further. The 11.6K protein migrates as multiple diffuse bands having apparent Mws of about 14,000, 21,000, and 31,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Immunoblotting as well as virus mutants with deletions in the 11.6K gene were used to show that the various gel bands represent forms of 11.6K. The 11.6K protein was synthesized in very low amounts during early stages of infection, from the scarce E3 mRNAs d and e which initiate from the E3 promoter. However, 11.6K was synthesized very abundantly at late stages of infection, approximately 400 times the rate at early stages, from new mRNAs termed d' and e'. Reverse transcriptase-polymerase chain reaction and RNA blot experiments indicated that mRNAs d' and e' had the same body (the coding portion) and the same middle exon (the y leader) as early E3 mRNAs d and e, but mRNAs d' and e' were spliced at their 5' termini to the major late tripartite leader which is found in all mRNAs in the major late transcription unit. mRNAs d' and e' and the 11.6K protein were the only E3 mRNAs and protein that were scarce early and were greatly amplified at late stages of infection. This suggests that specific cis- or trans-acting sequences may function to enhance the splicing of mRNAs d' and e' at late stages of infection and perhaps to suppress the splicing of mRNAs d and e at early stages of infection. We propose that the 11.6K gene be considered not only a member of region E3 but also a member of the major late transcription unit.

Adenoviridae↗
PubMed1992

Transcervical prostatectomy in perspective.

In a prospective study, 175 consecutive patients were included in transcervical prostatectomy. The results of the operation were evaluated by the mean weighted score and the postoperative morbidity. Although, urethral catheter was routinely removed on the second postoperative day, there was no evidence of suprapubic urinary fistula, clot retention or incontinence of urine noticed in any patient. Recatheterisation was required only in 2 patients for atony of the bladder muscles. Apart from wound infection in 3.4%, there was no other morbidity encountered with this technique. It is encouraging that about 77% of the patients went home before the fifth postoperative day and only one patient died on the second day. The merits of this technique have been highlighted in perspective with other studies reported in the literature.

Aged↗
PubMed1991

Smoking habits and carcinoma of the stomach: a case-control study.

Over a period of 8 years, a case-control study was carried out on smoking habits in 117 patients with carcinoma of the stomach and 234 controls, and a significant association of a particular method of smoking with the site of gastric carcinoma was found in the cancer patients. Furthermore, there was a highly significant difference in method of smoking between the cancer patients and the control group. The prevalence of smoking habit in the latter was 37%, of which 26% had swallowed the smoke regularly. In contrast, the incidence of smoking habit in the cancer patients was over 56%, of which 64% had swallowed the tobacco smoke. The difference is highly significant (P less than 0.001). The study also suggests that the distal part, in particular, the antrum of the stomach was affected more frequently among the smokers of the cancer patients who had swallowed the smoke regularly but the cardiac end seemed to be involved more often in the other groups of the cancer patients. These included 'never-smokers,' ex-smokers and those smokers who did not swallow the smoke (P less than 0.01). It is therefore concluded that the swallowing of tobacco smoke seems to influence the site of gastric carcinoma. The relative risk was six-fold higher among the smokers who did swallow the smoke compared with the 'never-smokers' of the control group.

Adult↗
PubMed1991

Recovery of injured Campylobacter jejuni cells after animal passage.

Sixteen freeze-thaw-injured nonculturable stocks of Campylobacter jejuni were passed through rat gut, and seven were reisolated. These reisolated strains were converted to toxin producers, as they were before preservation, following consecutive passages through rat gut. This observation indicated the existence of an injured, viable, but nonresuscitated form of C. jejuni which can be resuscitated to a culturable and fully virulent form by passaging the organism through a susceptible host.

Animals↗
PubMed1991

Adenovirus E3 14.7K protein functions in the absence of other adenovirus proteins to protect transfected cells from tumor necrosis factor cytolysis.

A 14,700-kDa protein (14.7K) encoded by the E3 region of adenovirus has been shown to protect adenovirus-infected mouse C3HA cells from lysis by tumor necrosis factor (TNF) (L. R. Gooding, L. W. Elmore, A. E. Tollefson, H. A. Brady, and W. S. M. Wold, Cell 53:341-346, 1988). These infected cells are sensitized to TNF by expression of the adenovirus E1A proteins (P. Duerksen-Hughes, W. S. M. Wold, and L. R. Gooding, J. Immunol. 143:4193-4200, 1989). In this study we show that 14.7K suppresses TNF cytolysis independently of adenovirus infection. Mouse C3HA and C127 cells were transfected with the 14.7K gene controlled by the mouse metallothionein promoter, and permanent 14.7K-expressing cell lines were tested for sensitivity to TNF cytolysis. Transfected cells which were sensitized to TNF either by inhibitors of protein synthesis, microfilament-destabilizing agents, or adenovirus infection were found to be resistant to TNF cytolysis. Two monoclonal antibodies were isolated and used to quantitate 14.7K in transfected and infected cells. Enzyme-linked immunosorbent assay (ELISA) analysis with these monoclonal antibodies and 14.7K immunoblots showed that 14.7K expression can be induced with cadmium in C3HA and C127 transfectants. The 14.7K induction correlated with a dose-dependent decrease in sensitivity to TNF cytotoxicity. The 14.7K protein does not substantially alter cell surface TNF receptor numbers or affinity on C3HA mouse fibroblasts, as determined by Scatchard analysis of 125I-TNF binding. The 14.7K protein also does not alter TNF signal transduction in general, because TNF induction of cell surface class I major histocompatibility complex molecules on 14.7K transfectants was unmodified. Our findings indicate that the adenovirus 14.7K protein functions as a specific inhibitor of TNF cytolysis in the absence of other adenovirus proteins and thus is a unique tool to study the mechanism of TNF cytotoxicity.

Adenoviridae↗
PubMed1991

The 10,400- and 14,500-dalton proteins encoded by region E3 of adenovirus form a complex and function together to down-regulate the epidermal growth factor receptor.

In adenovirus-infected cells, the epidermal growth factor receptor (EGF-R) is internalized from the cell surface via endosomes and is degraded, and the E3 10,400-dalton protein (10.4K protein) is required for this effect (C. R. Carlin, A. E. Tollefson, H. A. Brady, B. L. Hoffman, and W. S. M. Wold, Cell 57:135-144, 1989). We now report that both the E3 10.4K and E3 14.5K proteins are required for this down-regulation of EGF-R in adenovirus-infected cells. Down-regulation of cell surface EGF-R was demonstrated by results from several methods, namely the absence of EGF-R autophosphorylation in an immune complex kinase assay, the inability to iodinate EGF-R on the cell surface, the formation of endosomes containing EGF-R as detected by immunofluorescence, and the degradation of the metabolically [35S]Met-labeled fully processed 170K species of EGF-R. No effect on the initial synthesis of EGF-R was observed. This down-regulation was ascribed to the 10.4K and 14.5K proteins through the analysis of cells infected with rec700 (wild-type), dl748 (10.4K-, 14.5K+), or dl764 (10.4K+, 14.5K-) or coinfected with dl748 plus dl764. Further evidence that the 10.4K and 14.5K proteins function in concert was obtained by demonstrating that the 10.4K protein was coimmunoprecipitated with the 14.5K protein by using three different antisera to the 14.5K protein, strongly implying that the 10.4K and 14.5K proteins exist as a complex. Together, these results indicate that the 10.4K and 14.5K proteins function as a complex to stimulate endosome-mediated internalization and degradation of EGF-R in adenovirus-infected cells.

Adenoviridae↗
PubMed1991

Maximal aerobic capacity of Bengali girl athletes of different sports activities.

The maximal aerobic capacity (VO2max) and related cardiorespiratory parameters were determined on 67 Bengalee (Indian) girl athletes having nine different sports activities. VO2max was determined with a bicycle ergometer. The highest value for VO2maxl.min-1 was obtained by javelin throwers (1.95), being followed by pentathletes (1.92) and long-distance runners (1.90), whereas the lowest value was achieved by handballers (1.45). When VO2max was expressed in ml.kg-1.min-1, the long-distance runners registered the highest mean value (43.0), which was significantly higher than that of basketballers (34.9), handball players (36.2), badminton players (34.4), and swimmers (36.0). For this measurement, the sprinters (40.0), pentathletes (40.3), javelin throwers (40.0), and jumpers (39.4) did not differ significantly with each other, but each of the groups was significantly superior to basketballers, handballers, badminton players, and swimmers. No significant difference was also found amongst the latter groups. VO2maxl.min-1 was found to be significantly correlated with all the physical characteristics. It was predicted on the basis of age, height, weight, and body surface area using stepwise regression method.

Adolescent↗
PubMed1991

Better preservation of Campylobacter jejuni/C. coli in a defined medium.

Campylobacter jejuni and C. coli strains were preserved at -10 degrees C in different stock media to determine their efficacy to preserve the organism for a longer period of time. An improved defined stock culture medium was developed for the organism by removal and effective neutralisation of the toxic metabolites. Comparative study revealed that phosphate buffer saline (PBS), pH 6.7 supplemented with 0.2 per cent charcoal, 0.025 per cent FBP (ferrous sulphate, sodium metabisulphate and sodium pyruvate), 0.1 per cent L-cystein and 10 per cent glycerol could support survival of C. jejuni coli strains for as long as 135 days at -10 degrees C followed by George's medium, brucella broth with 15 per cent glycerol, fetal calf serum with 50 per cent TSYB (tryplicase soy yeast-broth) and glycerol transport broth respectively.

Bacteriological Techniques↗
PubMed1990

A 6700 MW membrane protein is encoded by region E3 of adenovirus type 2.

There is an open reading frame between ATG1022 and TGA1205 in the E3 transcription unit of adenovirus 2 that could encode a protein of MW 6700 (6.7K) (61 amino acids). To address whether this protein is expressed, we prepared an antiserum against a synthetic peptide corresponding to residues 47-61 in the 6.7K protein. This antiserum immunoprecipitated two series of protein bands, a 7K-8K doublet and a 15K-16K doublet or triplet, as observed by electrophoresis on 10-18% gradient SDS-polyacrylamide gels. These bands were not obtained from cells infected with mutants that lack the 6.7K gene. Most, if not all, of the 7K-8K and 15K-16K bands were detected by immunoblot, indicating that they are modified versions of the 6.7K protein. Only an 8K band was observed after cell-free translation of hybridization-purified mRNA, suggesting that this may be the primary translation product. As judged by DNA sequence, the 6.7K protein has a hydrophobic domain of at least 22 residues (residues 16-37), suggesting that 6.7K may be a membrane protein. Consistent with this, the 7K-8K and 15K-16K bands were observed in the crude membrane but not the cytosol or nuclear fractions of biochemically fractionated cells. The 6.7K protein was underproduced by mutants which underproduce E3 mRNAs a and c, indicating that 6.7K is translated from these mRNAs. Since the E3-gp 19K protein is also translated from mRNAs a and c, these mRNAs are bicistronic. The 6.7K protein is well-conserved in Ad5 (Ad2 and Ad5 are group C adenoviruses), and appears to be marginally conserved in Ad3 (group B).

Adenovirus Early Proteins↗
PubMed1990

Production and characterisation of Campylobacter jejuni enterotoxin in a synthetic medium and its assay in rat ileal loops.

A synthetic medium for production of Campylobacter jejuni enterotoxin was developed for the purposes of its purification by modifying syncase medium, replacing sucrose with glucose, and supplementing with 0.025% sodium pyruvate, 0.25% sodium metabisulphite, 0.001% ferric chloride and 0.1% L-cysteine, adjusted to pH 6.7. Culture filtrates of a human diarrhoeal and a chicken isolate, grown in this medium caused fluid accumulation ranging between 0.50-0.70 ml/cm of rat ileal loop. The kinetics of toxin production indicated a peak at 36 h and decline by 72 h, coinciding with the period of release of protease by the organism. At least 0.4 rat ileal loop units of enterotoxic activity was recovered per ml of culture filtrates and one unit of this toxin contained only 14 micrograms of protein. The toxin is heat-labile, pH dependent, nonhaemolytic, resistant to trypsin, sensitive to papain and pronase and may show subunit molecular weight analogy with CT subunits.

Animals↗