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Biomedical subjects

S Bhattacharyya

Publications and source records attributed to S Bhattacharyya.

At least 73 records · Page 4Linked to original sources
PubMed1998

A cognate tRNA specific conformational change in glutaminyl-tRNA synthetase and its implication for specificity.

Conformational changes that occur upon substrate binding are known to play crucial roles in the recognition and specific aminoacylation of cognate tRNA by glutaminyl-tRNA synthetase. In a previous study we had shown that glutaminyl-tRNA synthetase labeled selectively in a nonessential sulfhydryl residue by an environment sensitive probe, acrylodan, monitors many of the conformational changes that occur upon substrate binding. In this article we have shown that the conformational change that occurs upon tRNA(Gln) binding to glnRS/ATP complex is absent in a noncognate tRNA tRNA(Glu)-glnRS/ATP complex. CD spectroscopy indicates that this cognate tRNA(Gln)-induced conformational change may involve only a small change in secondary structure. The Van't Hoff plot of cognate and noncognate tRNA binding in the presence of ATP is similar, suggesting similar modes of interaction. It was concluded that the cognate tRNA induces a local conformational change in the synthetase that may be one of the critical elements that causes enhanced aminoacylation of the cognate tRNA over the noncognate ones.

2-Naphthylamine↗
PubMed1998

Tamoxifen up-regulates oestrogen receptor-alpha, c-fos and glyceraldehyde 3-phosphate-dehydrogenase mRNAs in ovine endometrium.

Tamoxifen, the antiestrogen most widely used in medicine, was tested in ewes to determine whether it antagonizes oestradiol up-regulation of ER, PR, and other genes reported to be oestrogen-modulated (c-fos, oxytocin receptor (OTR), glyceraldehyde phosphate dehydrogenase (GAPDH), and apolipoprotein AI (apo AI)) in endometrium and liver. Ovariectomized ewes (n = 6 ewes per group) were injected with 20 mg tamoxifen (Tam) 24 h prior to tissue collection, 50 microg oestradiol (E2) 18 h prior to tissue collection, both drugs (T + E2) or drug vehicle (Con). E2 treatment resulted in 857 +/- 93 pg oestradiol/g endometrium. Gross uterine characteristics of Tam- and T + E2-treated ewes were intermediate to those in Con and E2 groups. In endometrium, Tam treatment mimicked E2 treatment in up-regulating ER, c-fos, and GAPDH mRNAs two- or three-fold. However, neither E2 nor Tam treatments affected concentrations of OTR mRNA in endometrium, or ER, c-fos, GAPDH, OTR and apo AI mRNAs in liver. Like oestradiol, tamoxifen stabilized endometrial ER mRNA more than 3-fold in endometrial explants cultured with the transcription inhibitor 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB). Thus, tamoxifen acts as an oestradiol agonist in ovine endometrium and shares a posttranscriptional mechanism with oestradiol in the up-regulation of ER gene expression.

Animals↗
PubMed1998

A genome scan for loci influencing total serum immunoglobulin levels: possible linkage of IgA to the chromosome 13 atopy locus.

Immunoglobulins play an essential part in the immune system, and immunoglobulin deficiencies can have profound medical consequences. The genetic control and regulation of the immunoglobulin response is therefore of interest. Previous investigations have identified a number of loci influencing total and specific IgE levels. In this study, 80 nuclear families have been examined for linkage of total serum IgA, IgG and IgM levels to a genome-wide panel of microsatellite markers. Potential quantitative trait loci influencing IgA levels have been identified on chromosomes 10 and 13, and possible loci influencing IgG levels were found on chromosomes 3 and 13. No significant linkages to IgM levels were found. The linkage of IgA on chromosome 13 was to a marker previously linked to IgE responses (atopy). Linkage to IgG was in the same region but to a more distal marker. None of the factors known to influence immunoglobulin expression map to the loci identified in the present study. These loci are therefore likely to contain previously unrecognized components of the immunoregulatory system.

Chromosomes, Human, Pair 13↗
PubMed1997

Cyclin-dependent kinase regulation of the replication functions of polyomavirus large T antigen.

The amino-terminal portion of polyomavirus (Py) large T antigen (T Ag) contains two phosphorylation sites, at T187 and T278, which are potential substrates for cyclin-dependent kinases (CDKs). Our experiments were designed to test whether either or both of these sites are involved in the origin DNA (ori DNA) replication function of Py T Ag. Mutations were generated in Py T Ag whereby either or both threonines were replaced with alanine, generating T187A, T278A, and double-mutants (DM [T187A T278A]) mutant T Ags. We found that the Py ori DNA replication functions of T278A and DM, but not T187A, mutant T Ags were abolished both in vivo and in vitro. Consistent with this finding, it was shown that the ori DNA binding and unwinding activities of mutant T278A Py T Ag were greatly impaired. Moreover, whereas wild-type Py T Ag is an efficient substrate for phosphorylation by cyclin A-CDK2 and cyclin B-cdc2 complexes, it is phosphorylated poorly by a cyclin E-CDK2 complex. In contrast to mutant T187A, which behaved similarly to the wild-type protein, T278A was only weakly phosphorylated by cyclin B-cdc2. These data thus suggest that T278 is an important site on Py T Ag for phosphorylation by CDKs and that loss of this site leads to its various defects in mediating ori DNA replication. S- and G2-phase-specific CDKs, but not a G1-specific CDK, can phosphorylate wild-type T Ag, which suggests yet another reason why DNA tumor viruses require actively cycling host cells.

Antigens, Polyomavirus Transforming↗
PubMed1997

General cardinality genetic algorithms

A complete generalization of the Vose genetic algorithm model from the binary to higher cardinality case is provided. Boolean AND and EXCLUSIVE-OR operators are replaced by multiplication and addition over rings of integers. Walsh matrices are generalized with finite Fourier transforms for higher cardinality usage. Comparison of results to the binary case are provided.

Journal Article↗
PubMed1997

Paracetamol poisoning in the north east of England: presentation, early management and outcome.

1. Paracetamol is increasingly involved in self-poisoning in the United Kingdom and remains a common cause of fatal poisoning. 2. To document the epidemiology and early management of paracetamol poisoning data were collected on consecutive patients with suspected paracetamol poisoning presenting to 6 hospitals in the North East of England over 12 weeks in 1994. 3. There were 400 presentations (attendance rate 1.14/10(3) population/yr) involving 343 persons (45% male). Paracetamol concentrations at 4 h correlated weakly with reported paracetamol dose (R = 0.49, P < 0.0001) and were similar comparing those treated and not treated by gastric decontamination. 4. In 38 (9%) cases paracetamol concentrations were above the appropriate nomogram treatment line, including 3% and 20% of patients who reported ingesting less than and more than 12 g respectively. In 21 patients acetylcysteine treatment was deferred until admission to the ward, the mean delay involved was 2.8 h. 5. One patient died, from arrhythmias caused by co-ingested dothiepin. 6. Paracetamol poisoning is common. Most cases do not have potentially toxic plasma paracetamol concentrations, but those who do often present late and antidotal treatment may be delayed inappropriately.

Acetaminophen↗
PubMed1997

Studies on the aerobic photooxidation of cysteine using riboflavin as a sensitizer: evidence for the photogeneration of a superoxide anion and hydrogen peroxide.

The riboflavin sensitized oxidation of cysteine under an aerobic condition was investigated. The effects of various scavengers, such as superoxide dismutase, catalase, mannitol, sodium azide and potassium ferrocyanide (an electron donor), on the photooxidation were determined. A reaction mechanism involving the superoxide anion is proposed for the photooxidation of cysteine to cysteic acid.

Cysteine↗
PubMed1997

A comparative study of silver binding nucleolar organiser regions (AgNORs) of breast lesions in histological sections and fine needle aspiration smears.

The study presents a comparative profile of AgNOR dot counting in different types of breast lesions in histopathological (HP) sections and fine needle aspiration cytology (FNAC) smears. The breast lesions chosen were non-neoplastic lesion like fibroadenosis, benign neoplastic lesion like fibroadenoma and malignant neoplastic lesion like infiltrating duct carcinoma-grade 2. The AgNOR counts of non-neoplastic lesion were significantly less in number than the neoplastic lesions--both benign and malignant, in both the HP section and FNAC smear. But the counts did not show significant difference in the two neoplastic lesions eg, fibroadenoma and infiltrating duct carcinoma-grade 2, in both the HP section and FNAC smear. The appearance of the dots, as felt by the observers, were more discriminating between the three lesions, eg, uniform small compact centrally placed in fibroadenosis; mostly uniform small compact but occasional large irregular in fibroadenoma and large irregular marginally located in infiltrating duct carcinoma. Counting was easier and the appearance of the dots more easily discernible in FNAC smear than the HP section as the smear was monolayer and the malignant cells were easily detected from macrophages and stromal cells. But the tissue fluid or secretions or blood when present in the smear gave the smear a dirty background which was disturbing to the observers. Thus this AgNOR technique, when applied in HP section or FNAC smear, appears cost ineffective, lengthy and tedious procedure; did not offer absolute histochemical discriminant for malignancy from benignancy. But the shape and size distribution and appearance of the dots showing much variability in FNAC smear than the HP section, might be of some help in the diagnosis of malignancy and discriminating from benignancy.

Biopsy, Needle↗
PubMed1997

Melatonin action on thyroid activity in the soft-shelled turtle, Lissemys punctata punctata.

Adult female turtles (Lissemys punctata punctata) were treated with pineal indoleamine melatonin (100 micrograms/100 g) or the antithyroid agent, methylthiouracil (100 micrograms/100 g) or melatonin together with methylthiouracil (100 micrograms of each drug/100 g) for 12 days. Melatonin alone inhibited thyroid activity as evidenced by reduction in the gland weight, follicular epithelial cell height, thyroid peroxidase, and plasma thyroxine levels. Methylthiouracil caused hyperplasia of the gland, although it inhibited thyroid activity and reduced thyroid peroxidase and plasma thyroxine levels. Melatonin together with methylthiouracil produced changes similar to those obtained with melatonin alone. The results indicate that melatonin probably exerts inhibitory effects influences on both thyrotropin release from the pituitary and the activity of the thyroid itself in turtles.

Animals↗
PubMed1996

Downstream signaling molecules bind to different phosphorylated immunoreceptor tyrosine-based activation motif (ITAM) peptides of the high affinity IgE receptor.

The cytoplasmic tails of both the beta and gamma subunits of the high affinity IgE receptor (FcepsilonRI) contain a consensus sequence termed the immunoreceptor tyrosine-based activation motif (ITAM). This motif plays a critical role in receptor-mediated signal transduction. Synthetic peptides based on the ITAM sequences of the beta and gamma subunits of FcepsilonRI were used to investigate which proteins associate with these motifs. Tyrosine-phosphorylated beta and gamma ITAM peptides immobilized on beads precipitated Syk, Lyn, Shc, Grb2, and phospholipase C-gamma1 from lysates of rat basophilic leukemia RBL-2H3 cells. Syk was precipitated predominantly by the tyrosine-diphosphorylated gamma ITAM peptide, but much less by the diphosphorylated beta ITAM peptide or by the monophosphorylated peptides. Phospholipase C-gamma1, Shc, and Grb2 were precipitated only by the diphosphorylated beta ITAM peptide. Non-phosphorylated ITAM peptides did not precipitate these proteins. In membrane binding assays, fusion proteins containing the Src homology 2 domains of phospholipase C-gamma1, Shc, Syk, and Lyn directly bound the tyrosine-phosphorylated ITAM peptides. Although the ITAM sequences of the beta and gamma subunits of FcepsilonRI are similar, once they are tyrosine-phosphorylated they preferentially bind different downstream signaling molecules. Tyrosine phosphorylation of the ITAM of the gamma subunit recruits and activates Syk, whereas the beta subunit may be important for the Ras signaling pathway.

Amino Acid Sequence↗
PubMed1996

Presentation of poisoned patients to accident and emergency departments in the north of England.

1. A 12 week prospective survey of all patients of any age with confirmed or suspected poisoning presenting to six accident and emergency departments in the North East of England was performed to establish the local incidence and patterns of presentation of poisoning. 2. 945 episodes of poisoning involving 852 patients were recorded representing approximately 1.2% of all A&E presentations and suggesting an annual attendance rate of 2.7 per 1000 persons per year. 3. Attendance rates varied threefold between hospitals and were similar in males and females overall; between the ages of five and 14 attendances were more common in females (1.9 vs 0.6/10(3)/y) while between 0 and 4 y (3.1 vs 2.4) and 25 and 34 y (3.9 vs 2.9/10(3)/y) they were more common in males. 4. The median interval between poisoning and presentation was 2 h (mean 4.1 h) and only 19% of cases presented within 1 h. Presentation was most common between Friday evening and Tuesday morning and in the late afternoon and evening. 5. 6% of the patients presented more than once with poisoning during the study period and 37% had a past history of deliberate self-harm. The most common poisons involved were paracetamol (43%), opioids (15%) and benzodiazepines (15%). 6. The study illustrates the frequency of presentations of poisoning to A&E departments. The high rate of poisoning in young men and the increasing use of paracetamol are particular causes for concern.

Acetaminophen↗
PubMed1996

Factors affecting hospital admission and length of stay of poisoned patients in the north east of England.

1. Poisoning is a common reason for presentation to hospital and hospital admission but there is no agreed policy for managing these patients. This study examined the management of patients presenting with poisoning and the factors affecting the probability of hospital admission and prolonged stay. 2. Data on all cases of poisoning presenting to six Accident and Emergency departments in the North East of England over 12 weeks in 1994 was collected prospectively from A&E notes. Length of stay and outcome were recorded from hospital computer records. 3. Overall, 73% of patients were admitted to a medical ward. Probability of admission was not independently affected by age or gender but was increased in those with intentional poisoning (Odds Ratio (OR) 3.3 [95% CI 1.8, 6.1]), a history of self harm (OR 1.7, [1.0, 2.9]) or potentially hazardous poisoning (OR 3.7 [2.1, 6.6]). There were significant variations between hospitals (50-80%) which could not be attributed to case mix. 4. Prolonged stay (> 2 nights) was more common in patients over 65 years (OR 6.8 [2.9, 16.1]), those with intentional poisoning (OR 2.7 [1.1, 6.6]) and those with potentially hazardous poisoning (OR 2.6 [1.4, 4.9]). Mean hospital stay was 1.5 days and varied significantly between hospitals from 0.8 to 2.1 days and this was independent of case mix. 5. There are appreciable variations in the management of poisoning between hospitals which are not explained by patient characteristics. Savings would occur if rates of admission and duration of stay were reduced by those hospitals where admission is more frequent or hospital stay is longer. However, the impact of this on long term morbidity is unknown.

Adolescent↗
PubMed1996

Regeneration of encapsulated protocorms of Phaius tankervilliae stored at low temperature.

Embryos (80 days old) developed after selfing P. tankervilliae were cultured on Nitsch medium for protocorm development. Protocorms (70 days old) thus developed were encapsulated with alginate matrix. Ninety six per cent of freshly prepared encapsulated protocorms differentiated into shoots and roots when cultured on Nitsch medium. Storage of encapsulated protocorms in sealed petri plates or by embedding in liquid paraffin at 4 degrees C showed no reduction in their regeneration frequency up to 120 days when cultured on Nitsch medium. However, 90% of encapsulated protocorms stored at room temperature in empty petri plates differentiated within 35-40 days. Regeneration frequency of encapsulated protocorms was drastically reduced when stored in liquid paraffin at room temperature.

Alginates↗
PubMed1996

Pulmonary infection caused by Mycobacteria other than M. tuberculosis in and around Calcutta.

A study was undertaken to determine the prevalence rate of atypical mycobacteria in indolent fibrocavitary pulmonary diseases. 450 sputum specimens were examined and cultured, of which 15 were identified as atypical mycobacteria on repeated culture. No previous study was recorded from Calcutta. Compared to the results of previous workers from different regions of India, the prevalence rate seems high in this part of the country.

Adult↗