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S Das

Publications and source records attributed to S Das.

At least 181 records · Page 10Linked to original sources
PubMed2000

Eukaryotic translation initiation factor 5 functions as a GTPase-activating protein.

Eukaryotic translation initiation factor 5 (eIF5) forms a complex with eIF2 by interacting with the beta subunit of eIF2. This interaction is essential for eIF5-promoted hydrolysis of GTP bound to the 40 S initiation complex. In this work, we show that, in addition to the eIF2 beta-binding region at the C terminus of eIF5, the N-terminal region of eIF5 is also required for eIF5-dependent GTP hydrolysis. Like other GTPase-activating proteins, eIF5 contains an invariant arginine residue (Arg-15) at its N terminus that is essential for its function. Mutation of this arginine residue to alanine or even to conservative lysine caused a severe defect in the ability of eIF5 to promote GTP hydrolysis from the 40 S initiation complex, although the ability of these mutant proteins to bind to eIF2 beta remained unchanged. These mutants were also defective in overall protein synthesis as well as in their ability to support cell growth of a Delta TIF5 yeast strain. Additionally, alanine substitution mutagenesis of eIF5 defined Lys-33 and Lys-55 as also critical for eIF5 function in vitro and in vivo. The implications of these results in relation to other well characterized GAPs are discussed and provide additional evidence that eIF5 functions as a GTPase-activating protein.

Amino Acid Motifs↗
PubMed2000

Quality improvement initiative and its impact on the management of patients with acute myocardial infarction.

BACKGROUND: Wide variation exists in acute myocardial infarction (AMI) management, leading to differences in outcomes. OBJECTIVE: To assess the impact of the quality improvement initiative on appropriate management of AMI. DESIGN: Prospective patient identification, retrospective medical record review. PATIENTS: All patients with AMI discharged alive (N = 497) from our institution between April 1, 1995, and February 28, 1997. MAIN OUTCOME MEASURE: The effect of quality improvements directed at the patient, nurse, and physician on the adherence to key quality indicators. RESULTS: The quality improvement initiative correlated with more frequent use of reperfusion therapy (98%), and with aspirin use in the emergency department (95%), in ideal eligible patients. Similarly, adherence to discharge quality indicators, including use of aspirin (97%), beta-blockers (94%), angiotensin-converting enzyme inhibitors (90%), and lipid-lowering agents (67%); avoidance of calcium channel blockers (93%); a low-fat diet (96%); smoking cessation counseling (94%); and outpatient rehabilitation referral (70%) was higher, including in the very old (those aged >/=80 years) and in women. The use of a patient education tool was associated with a higher adherence to most quality indicators compared with patients in whom this was not used: discharge aspirin (99% vs 96%; P =.02), beta-blocker (98% vs 91%; P =.002), angiotensin-converting enzyme inhibitor (95% vs 86%; P =.01), and lipid-lowering agent (71% vs 62%; P =.04) use; outpatient rehabilitation (82% vs 63%; P=.001); and documentation of smoking cessation counseling (98% vs 87%; P =. 001). CONCLUSIONS: Implementation of a quality improvement program was associated with a high adherence to quality-of-care indicators for AMI. Patient-directed feedback before discharge improved adherence to key indicators for AMI beyond that achieved with tools only directed at caregivers.

Adult↗
PubMed2000

Partial paternal uniparental disomy of chromosome 6 in an infant with neonatal diabetes, macroglossia, and craniofacial abnormalities.

Neonatal diabetes, which can be transient or permanent, is defined as hyperglycemia that presents within the first month of life and requires insulin therapy. Transient neonatal diabetes mellitus has been associated with abnormalities of the paternally inherited copy of chromosome 6, including duplications of a portion of the long arm of chromosome 6 and uniparental disomy, implicating overexpression of an imprinted gene in this disorder. To date, all patients with transient neonatal diabetes mellitus and uniparental disomy have had complete paternal isodisomy. We describe a patient with neonatal diabetes, macroglossia, and craniofacial abnormalities, with partial paternal uniparental disomy of chromosome 6 involving the distal portion of 6q, from 6q24-qter. This observation demonstrates that mitotic recombination of chromosome 6 can also give rise to uniparental disomy and neonatal diabetes, a situation similar to that observed in Beckwith-Wiedemann syndrome, another imprinted disorder. This finding has clinical implications, since somatic mosaicism for uniparental disomy of chromosome 6 should also be considered in patients with transient neonatal diabetes mellitus.

Aneuploidy↗
PubMed2000

Activity and Conformation of Yeast Alcohol Dehydrogenase (YADH) Entrapped in Reverse Micelles.

Yeast alcohol dehydrogenase (YADH) solubilized in reverse micelles of aerosol OT (i.e., AOT or sodium bis (2-ethyl hexyl) sulfosuccinate) in isooctane has been shown to be catalytically more active than that in aqueous buffer under optimum conditions of pH, temperature, and water content in reverse micelles. Studies of the secondary structure conformational changes of the enzyme in reverse micelles have been made from circular dichroism spectroscopy. It has been seen that the conformation of YADH in reverse micelles is extremely sensitive to pH, temperature, and water content. A comparison has been made between the catalytic activity of the enzyme and the alpha-helix content in the conformation and it has been observed that the enzyme is most active at the maximum alpha-helix content. While the beta-sheet content in the conformation of the entrapped enzyme was found to be dependent on the enzyme-micelle interface interaction, the alpha-helix and random coil conformations are governed by the degree of entrapment and the extent of rigidity provided by the micelle core to the enzyme structure. Copyright 2000 Academic Press.

Journal Article↗
PubMed2000

The characterization of phospholipase D in FRTL-5 thyroid cells.

We previously demonstrated that TSH activates phospholipase D (PLD) in Fischer rat thyroid line (FRTL)-5 cells. To date, two types of mammalian phosphatidylcholine-specific PLD cDNAs, designated as PLD-1 and PLD-2, have been cloned. The present study determined the PLD isoform composition in FRTL-5 thyroid cells and which isoform is regulated by TSH. PLD-1 is activated by small molecular weight G-proteins, such as ADP-ribosylation factor (ARF) and RhoA family members, while PLD-2 is relatively independent of such stimuli. We established the presence of PLD-1 and PLD-2 by Western blot analysis and compared PLD activity in cytosol, membranes and combined fractions in the presence and absence of GTPgammaS. The membrane fraction showed very little activity in the absence of GTPgammaS, but this activity increased approximately 5-fold (P<0.05, ANOVA) in the presence of GTPgammaS. Maximal PLD activity was seen with the combination of membrane plus cytosolic fractions (which contained ARF and RhoA) where the addition of GTPgammaS increased PLD activity approximately 8-fold (P<0.05, ANOVA). To determine the relative activities of PLD-1 and PLD-2 in FRTL-5 thyroid cells, cell-free PLD assays were performed in the presence of GTPgammaS or GDPbetaS with varying concentrations of phosphatidylinositol 4,5-bisphosphate (PIP(2)). PLD-2 contributed only approximately 19% of the total amount of PLD activity in the membranes and PLD-1 was the predominant PLD isoform. TSH stimulated PLD-1 activity by up to 2. 3-fold over control values (P<0.01, ANOVA). To establish the dependence of PLD-1 on small molecular weight G-proteins, the translocations of ARF and RhoA to the membrane fractions was determined after stimulation by TSH. Both ARF and RhoA were maximally translocated to the membrane fraction after 10 min incubation with 100 microU/ml TSH by approximately 1.7- and 2.3-fold over control values, respectively (P<0.02 and P<0.03, ANOVA). It is concluded that TSH stimulates PLD-1 activity in FRTL-5 thyroid cells and this is accompanied by the translocation of ARF and RhoA to the membrane fraction.

Animals↗
PubMed2000

Amplification of various genes of human group B rotavirus from stool specimens by RT-PCR.

BACKGROUND: The detection of the human group B rotavirus (HuGBR) CAL strain from India has given us an opportunity to design suitable primers for the detection of HuGBR since CAL is the second HuGBR detected until now, the Chinese Adult Diarrhoea Rotavirus (ADRV) being the first reported human pathogen belonging to this group of viruses. The primers described here may thus be used for the detection of human group B rotaviruses by reverse transcription-PCR (RT-PCR) in a diagnostic laboratory. OBJECTIVE: To establish a set of primers suitable for the detection of various genes of human group B rotaviruses using a rapid RT-PCR assay. STUDY DESIGN: Until recently, the Chinese ADRV strain was the only HuGBR strain that had been partially sequenced by cloning various viral genes using vector-specific primers. Consequently, there are very few reports in the literature describing primers that may be used for the detection of HuGBR viruses using RT-PCR in a clinical laboratory. The sequences of various genes from the ADRV strain that had been submitted to the nucleotide sequence database GenBank were analyzed in order to design several putative detection primer pairs for an RT-PCR assay. The rationale was to amplify the cognate genes from five isolates of the HuGBR CAL strain (CAL-1 to CAL-5) that have been detected to date from India. Primers that resulted in a specific product of the expected size from the CAL isolates were used to standardize a protocol for amplifying various genes of the CAL isolates under identical reaction conditions. RESULTS: Out of several synthetic oligonucleotides designed, 12 were found to be satisfactory for the amplification of gene segments 4, 5, 6, 7, and 9 from the five CAL isolates and are presented here. A set of previously described primers that have been shown to be specific for human group B rotavirus gene segment 8 were also found to amplify the cognate gene from the CAL isolates. All the reactions were carried out using the same thermal cycling conditions. CONCLUSIONS: The extreme virulence potential of HuGBR has been documented in several epidemics in China. Until recently, the Chinese ADRV strain was the only known HuGBr strain. As there have not been any reports of HuGBR infections outside China, there are no consensus nucleotide sequences available for HuGBR that may be used to validate primers for the detection of HuGBR. Here we report a set of 12 primer sequences that were designed from ADRV sequences and also found to amplify various genes from the different CAL isolates and hence may represent consensus primers suitable for the detection of HuGBR.

DNA Primers↗
PubMed2000

Comparison of global transcription responses allows identification of Vibrio cholerae genes differentially expressed following infection.

Comparison of global transcription profiles of Vibrio cholerae grown in vitro and in vivo revealed that 20% of the genome was repressed and about 5% was induced under in vivo conditions. Hybridization with the cloned genes revealed that the virulence genes ctx, toxR, toxT and tcpA were induced under in vivo conditions. Dissection of two in vivo induced cosmids identified another set of three genes homologous to che Y1 involved in motility and chemotaxis, pnuC encoding the major component of the nicotinamide mononucleotide transport system and icmF belonging to a cassette involved in multiplication inside host cells. These results demonstrate that the global transcription profile approach might be a powerful method for identification of differentially expressed transcripts under in vivo conditions.

Animals↗
PubMed2000

Donor liver uridine diphosphate (UDP)-glucuronosyltransferase-1A1 deficiency causing Gilbert's syndrome in liver transplant recipients.

BACKGROUND: Uridine diphosphate-glucuronosyltransferase-1A1 deficiency, causing Gilbert's syndrome, has been attributed to two extra (TA) bases in the TATAA-box of the promoter region of its gene, where the A(TA)6TAA allele corresponds to the normal gene and A(TA)7TAA corresponds to a gene with reduced expression. Our aim was to determine whether isolated hyperbilirubinemia in liver transplant recipients was due to Gilbert's syndrome acquired through the liver allograft. METHODS: From 305 patients followed in our Liver Transplant Clinic, five patients with isolated unconjugated hyperbilirubinemia in the absence of hemolysis, recurrent viral hepatitis, and biliary tract pathology were identified; 10 other post-orthotopic liver transplantion patients with normal liver chemistry tests were randomly selected as a control group. DNA was extracted from paraffin-embedded liver allograft tissue and peripheral lymphocytes and was genotyped for the TA repeat at the uridine diphosphate glucononosyltransferase-lA1 promoter region by polymerase chain reaction and acrylamide gel electrophoresis. Homozygosity for the (TA)7 allele was considered diagnostic of Gilbert's syndrome. RESULTS: The mean serum total bilirubin level of the study patients was 2.28 mg/dl (range 1.8-3.0), consisting predominantly of the unconjugated form; that of the control patients was 0.76 mg/dl (range 0.4-1.1). The liver tissue from all five patients in the study group possessed the homozygous A(TA)7TAA genotype that was not observed in their lymphocytes. None of the liver tissue from the control patients demonstrated homozygosity for the A(TA)7TAA allele. CONCLUSION: Uridine diphosphate-glucuronosyltransferase-1A1 deficiency, causing Gilbert's syndrome, may be carried by the donor liver and present with isolated unconjugated hyperbilirubinemia in liver transplant recipients.

Adult↗
PubMed2000

Isolation and functional characterization of a temperature-sensitive mutant of the yeast Saccharomyces cerevisiae in translation initiation factor eIF5: an eIF5-dependent cell-free translation system.

Eukaryotic translation initiation factor 5 (eIF5) interacts with the 40S ribosomal initiation complex (40S.eIF3.AUG.Met-tRNA(f).eIF2.GTP) to promote the hydrolysis of bound GTP. In Saccharomyces cerevisiae, eIF5, a protein of 45346Da, is encoded by a single-copy essential gene, TIF5. In this paper, we have isolated a temperature-sensitive S. cerevisiae strain, TMY5-1, by replacing the wild-type chromosomal copy of TIF5 with one mutagenized in vitro. The mutant yeast cells rapidly cease protein synthesis when grown under non-permissive conditions, lose polyribosomes and accumulate free 80S ribosomes. Further characterization of mutant eIF5 showed that the mutant protein, expressed in Escherichia coli, is defective both in its interaction with eIF2 as well as in mediating the hydrolysis of GTP bound to the 40S initiation complex and consequently in the formation of the 80S initiation complex. Additionally, the availability of a yeast strain containing temperature-sensitive mutation in the eIF5 gene allowed us to construct a cell-free translation system that was dependent on exogenously added eIF5 for translation of mRNAs in vitro.

Cell-Free System↗
PubMed2000

Role of exogenous inositol and phosphatidylinositol in glycosylphosphatidylinositol anchor synthesis of GP49 by Giardia lamblia.

Although Giardia lamblia trophozoites are unable to carry out de novo phospholipid synthesis, they can assemble complex glycophospholipids from simple lipids and fatty acids acquired from the host. Previously, we have reported that G. lamblia synthesizes GP49, an invariant surface antigen with a glycosylphosphatidylinositol (GPI) anchor. It is therefore possible that myo-inositol (Ins), phosphatidylinositol (PI) and other GPI precursors are obtained from the dietary products of the human small intestine, where the trophozoites colonize. In this report, we have investigated the role of exogenous Ins and PI on GPI anchor synthesis by G. lamblia. The results demonstrate that [(3)H]Ins and PI internalized by trophozoites, metabolically transformed into GlcN(acyl)-PI and downstream GPI molecules. Further investigations suggest that G. lamblia expresses cytidine monophosphate (CMP)-dependent (Mg(2+)-stimulated) and independent (Mn(2+)-stimulated) inositol headgroup exchange enzymes, which are responsible for exchanging free Ins with cellular PI. We observed that 3-deoxy-3-fluoro-D-myo-inositol (3-F-Ins) and 1-deoxy-1-F-scyllo-Ins (1-F-scyllo-Ins), which are considered potent inhibitors of Mn(2+)-stimulated headgroup exchange enzyme, inhibited the incorporation of [(3)H]Ins into PI and GPI molecules significantly, suggesting that CMP-independent (Mn(2+)-stimulated) exchange enzyme may be important for these reactions. However, 3-F-Ins and 1-F-scyllo-Ins were not effective in blocking the incorporation of exogenously supplied [(3)H]PI into GPI glycolipids. Thus, it can be concluded that G. lamblia can use exogenously supplied [(3)H]PI and [(3)H]Ins to synthesize GPI glycolipids of GP49; while PI is directly incorporated into GPI molecules, free Ins is first converted into PI by headgroup exchange enzymes, and this newly formed PI participates in GPI anchor synthesis.

Animals↗
PubMed2000

Chemopreventive activity of quercetin during carcinogenesis in cervix uteri in mice.

The chemopreventive action of quercetin was examined during 20-methyl cholanthrene induced cervical neoplasia in virgin Swiss albino mice. The effects were evaluated on the basis of histopathological observation of the cervical epithelium, micronucleus frequency in vaginal exfoliated cells and some biochemical parameters in the host liver. Quercetin was found to arrest or reverse the progression of cervical neoplasia. The micronucleus frequency was reduced following its administration. The potential anti-carcinogenic effect of quercetin noted in this study is attributed to its antioxidant property which was reflected in the lipid peroxides and their role in the host detoxification system, as expressed in liver glutathione level, glutathione-S-transferase, glutathione peroxidase, catalase and superoxide dismutase activity. As an integral part of the diet quercetin may offer protection to the epithelium from the damaging effects of carcinogenic chemicals.

Animals↗
PubMed2000

Balanitis xerotica obliterans--a review.

Balanitis xerotica obliterans (BXO) is a scarcely known disease, wrongly considered rare. With a high degree of suspicion and histologic examination, the condition will prove to be much more frequent than one generally believes. The etiology of the condition is unknown at present. Many cases of BXO occurring after circumcision may be cases of secondary phimosis due to BXO not being recognized at the time of surgery. Most of the cases of BXO are seen in the third to fifth decades of life, even though they may occur at the extremes of age. Biopsy of the lesions is not essential in all cases and is indicated to differentiate from penile cancer and in atypical cases. Early diagnosis and treatment of BXO are very important in preventing the urological complications of the diseases such as urethral stricture. Treatment of BXO depends on the anatomic location of the lesions and their extent and severity, together with the rapidity of progression of the disease process. The treatment may vary from topical corticosteroids, laser vaporization in early cases to meatoplasty and urethroplasty in extensive cases. Topical pharmacotherapy is useful in the early stages to reduce the initial symptoms and slow down the progression, but is not effective in all cases and is not the curative treatment of disease. Meatal stenosis, phimosis, scar adhesions, fissures, erosions of glans and prepuce and involvement of the urethra are indications for surgical treatment. Surgery seems to be the only treatment that can relieve the symptoms of advanced disease. Modified circumcision, with total removal of inner preputial layer, definitively relieves phimosis without any recurrence. Meatotomy will not prevent the recurrence of meatal stenosis. Excision of the scleroatrophic tract and grafting of the glans base, coronal sulcus, and the end of the shaft give a complete relief of pain during erection and intercourse in circumcised patients with balanopreputial adhesions and restore the elasticity of the skin of penile shaft. These procedures have been shown to yield excellent functional results during a follow-up period of up to 4 years. BXO involving anterior urethra can be treated by 2-stage urethroplasty or substitution urethroplasty. The complete excision of the stricture and flap urethroplasty seems to be better than a 2-stage procedure. However, at the present time, it is not possible to say that surgery can completely resolve this chronic and progressive disease. Despite many reports in the literature of cases of BXO associated with squamous cell carcinoma, the etiologic relationship between the two conditions is uncertain.

Administration, Topical↗
PubMed2000

Target-cell-induced anergy in natural killer cells: suppression of cytotoxic function.

Our earlier studies have demonstrated that natural killer (NK) cells are the effectors that participate during the spontaneous regression of AK-5 tumour in syngeneic hosts. We have shown that the tumour cells are killed by necrosis and apoptosis. In this study, we have examined the induction of functional anergy in NK cells following coculture with fixed AK-5 tumour cells at high ratio. NK cells, upon coculture with fixed AK-5 cells (1:1 ratio), showed loss of cytotoxic function against both AK-5 (antibody-dependent cell cytotoxicity) as well as YAC-1 targets. The response of these cells to the activation by recombinant interleukin-2 and recombinant interferon gamma was poor. Induction of tumour necrosis factor alpha (TNFalpha) secretion was observed after coculture of NK cells with fixed AK-5 cells. The cocultured cell supernatant inhibited the cytotoxic activity of NK cells, which was partially restored with anti-TNFalpha antibody. In addition, NK cells, after treatment with fixed tumour cells showed overexpression of the Fas receptor. We have also observed induction of apoptosis in cocultured NK cells. These studies suggest that the fixed tumour cells (antigen) at high ratio are able to suppress NK cell function as well as induce death in NK cells.

Animals↗
PubMed2000

Pathology of Madras type of motor neuron disease (MMND)--a histological and immunohistochemical study.

A neuropathological report of Madras type of motor neuron disease (MMND) is presented and the differences from other forms of MND are discussed. An 18-year-old girl presented with nerve deafness and slowly progressive bulbo-spinal muscular atrophy, characteristic of MMND. Post-mortem examination of the spinal cord showed a severe loss of anterior horn cells, prominent dilatation of vessels, diffuse, but sparse sprinkling of microglial cells and lymphocytes, and demyelination and sclerosis of the ventrolateral columns. Neuronal depletion and marked gliosis was noted in the cochlear nucleus on both sides, while other bulbar motor nuclei were also involved. The cochlear nerve showed demyelination and axonal loss. Trigeminal and vestibular ganglia revealed features of ganglionitis. The possibility of an inflammatory aetiology for MMND needs to be considered.

Adolescent↗
PubMed2000

Prevalence of BRCA1 and BRCA2 mutations among clinic-based African American families with breast cancer.

To define the prevalence and relative contributions of BRCA1 and BRCA2 mutations among African American families with breast cancer, we analyzed 28 DNA samples from patients identified through two oncology clinics. The entire coding regions of BRCA1 and BRCA2 were screened by protein truncation test, heteroduplex analysis, or single-stranded conformation polymorphism followed by DNA sequencing of variant bands. Deleterious protein-truncating BRCA1 and BRCA2 mutations were identified in five patients or 18% of the entire cohort. Only 8% (1 of 13) of women with a family history of breast cancer, but no ovarian cancer, had mutations. The mutation rates were higher for women from families with a history of breast cancer and at least one ovarian cancer (three of six, 50%). One woman with a family history of undocumented cancers was also found to carry a deleterious mutation in BRCA2. The spectrum of mutations was unique in that one novel BRCA1 mutation (1625del5) and three novel BRCA2 mutations (1536del4, 6696delTC, and 7795delCT) were identified. No recurrent mutations were identified in this cohort, although one BRCA2 (2816insA) mutation had been previously reported. In addition, two BRCA1 and four BRCA2 missense mutations of unknown significance were identified, one of which was novel. Taken together with our previous report on recurrent mutations seen in unrelated families, we conclude that African Americans have a unique mutation spectrum in BRCA1 and BRCA2 genes, but recurrent mutations are likely to be more widely dispersed and therefore not readily identifiable in this population.

Adult↗
PubMed2000

An ergonomics study on compatibility of controls of overhead cranes in a heavy engineering factory in West Bengal.

Ergonomics studies, on the machine control and the resultant movements of the cabins and the hooks in 51 electric overhead travelling cranes in a heavy engineering factory, showed that control-movement compatibility is absent in most of the cranes. Also, the layout of the groups of controls and the orientations of each of the individual controls with respect to the operators' seats varied from one crane to another. As the operators were shifted from one crane to another every week, there was a high chance of making mistakes during moving the controls, which might have resulted in severe accidents, especially during periods of high workload. A number of low-cost ergonomics solutions have been recommended to minimize these problems.

Engineering↗