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Biomedical subjects

S K Saha

Publications and source records attributed to S K Saha.

At least 19 recordsLinked to original sources
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↗
PubMed1989

Acute lower respiratory infections: a major cause of death in children in Bangladesh.

The importance of acute lower respiratory infections (ALRI) as a cause of death in children was estimated using systematically collected demographic data on the population of the Teknaf area of southern Bangladesh. Of 1349 children aged 1-59 months who died between 1 January 1982 and 31 December 1985, ALRI was diagnosed by verbal autopsy in 390 (29%) and was the leading cause of death. ALRI mortality rates were highest in the youngest age groups (136/1000 for those less than or equal to 5 months) and decreased in older children (16/1000 for those 3-4 years old). Half of all fatal ALRI cases occurred in children less than 6 months old. In older children, ALRI-associated deaths tended to occur during the months October to January, while deaths in infants tended to follow the seasonal birth pattern. Significant predisposing factors for fatal ALRI were malnutrition and measles, detected, respectively, in 18% and 8% of children who died from ALRI. This study emphasizes the importance of ALRI as a major cause of death in developing countries and suggests that interventions to reduce childhood mortality are needed and should be targeted to specific age groups at risk.

Acute Disease↗
PubMed1989

Immunological studies on pulmonary tuberculosis: a preliminary report.

An investigation of 71 patients (61 mantoux positive and 10 mantoux negative) with bacteriologically and radiologically proven primary pulmonary tuberculosis was undertaken for immunological analysis to evaluate cell mediated (E-rosette) and humoral (EAC-rosette and serum immunoglobulins; IgG, IgA & IgM) immune status. 41 age and sex matched normal subjects served as controls. An inverse relationship between cell mediated and humoral immune response was observed in tuberculous patients in general. Defects in cell mediated immune response was pronounced in mantoux negative cases. Fractionation of serum protein revealed a significant diminution in albumin level with a concomitant elevation in globulins particularly gammaglobulin levels. It appeared that there is a definite need to boost up T-cell mediated responses and to control the over activity of B-cell in these cases. Proper handling of the immune system by appropriate therapy might change the course of the disease.

Female↗
PubMed1989

Better growth of Campylobacter jejuni using simple Fortner's principle & candle extinction jar.

C. jejuni isolated from patients of childhood diarrhoea and chicken intestines were examined for better growth in both liquid and solid media under three different environments of candle extinction jar with or without an Escherichia coli inoculated plate and three such plates in a sealed jar. Better growth by one log in liquid media was obtained at 24 and 48 h with bacterial counts of about ca. 10(7) and ca. 10(9) respectively, and larger colony size at 24 h on solid medium by inclusion of a single Esch. coli inoculated plate following Fortner's principle rather than candle jar alone. Inclusion of three Esch. coli plates yielded similar results at 48 h but lesser growth at 24 h and a decline at 72 h. Most of the C. jejuni strains failed to adapt to grow in presence of air.

Animals↗
PubMed1988

Enterotoxigenicity of chicken isolates of Campylobacter jejuni in ligated ileal loops of rats.

Ligated ileal loops in rats of the Charles-Foster strain, weighing 200-250 g and aged 7-8 months, provided a sensitive and reproducible means of testing the enterotoxigenicity of Campylobacter jejuni. All of 16 chicken isolates caused fluid accumulation comparable to that produced by toxigenic Vibrio cholerae O1, strain 569B. However, 11 of the isolates required one to three consecutive passages through the rat gut before doing so. The amount of fluid produced increased after each passage. Of three culture media tested, brucella broth of pH 6.7 supported the highest degree of enterotoxigenesis. Filtrates of cultures of all 16 chicken isolates in this medium were as effective as viable C. jejuni in producing fluid in ileal loops. The enterotoxin was neutralised completely by cholera antitoxin diluted 1 in 160, indicating its close immunobiological relationship to cholera toxin.

Animals↗