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Biomedical subjects

S Chaudhury

Publications and source records attributed to S Chaudhury.

At least 19 recordsLinked to original sources
PubMed2003

Emergence of novel human group A rotavirus G12 strains in India.

Three rare human G12 strains were detected from diarrheic clinical samples of children (<8 months of age) in Calcutta during a routine surveillance study of rotaviral diarrhea in India. The VP7 genes of G12 strains and their products showed maximum homology (97 to 99% at the nucleotide level and 98% at the amino acid level, respectively) with those of two recently reported G12 strains (from the United States and Thailand) but lesser homology with those of prototype G12 strain L26.

Antigens, Viral↗
PubMed2001

Thyroidal regulation of different isoforms of NaKATPase in glial cells of developing rat brain.

The developmental profile of the different isoforms of NaKATPase have been investigated during the first three weeks of postnatal development using primary cultures of isolated glial cells derived from neonatal rat cerebra. Northern and Western blot analysis show that the expression of four isoforms (alpha1, alpha2, beta1 and beta2) in these cells increases progressively between 5 to 20 days of culture. Comparison of the mRNA levels of these isoforms in thyroid hormone deficient (TH def) and thyroid hormone supplemented (TH sup) cells cultured for 5-10 days, revealed for the first time that all four isoforms are sensitive to T3 in the glial cells. Furthermore immunocytochemical staining of these cells with isoform specific NaKATPase antibodies also showed that the localization of the different isoforms in the TH def cells were altered in comparison to that in the TH sup cells. These results establish glial cells as the target cells for the regulation of NaKATPase by TH in the developing brain.

Animals↗
PubMed2001

Identification of thyroid regulatory elements in the Na-K-ATPase alpha3 gene promoter.

A -1027 bp to + 108 bp region of Na-K-ATPase alpha3 gene promoter has been searched for the presence of thyroid response elements (TRE). Computer analysis of this sequence using a consensus TRE sequence revealed the presence of four putative TRE rich regions referred to as regions I (-636 to -457 bp), II (-218 to -106 bp), III (-106 to -6 bp) and IV (-6 to +108 bp). Cotransfection of the luciferase linked full length construct as well as constructs progressively devoid of the TRE rich regions in Cos1 cells revealed that regions I and III are positively regulated by T3 whereas there are some sequences in region II which can suppress the positive regulatory effect of region III but not of region I. TRE IV seems to have no functional role. EMSA of the three functional TRE rich regions (I, II and III) showed strong and specific interaction with thyroid hormone receptor (TR) cloned and expressed in baculovirus. The overall results suggest the regulation of Na-K-ATPase alpha3 gene by T3 is complex involving several thyroidal regulatory elements.

5' Flanking Region↗
PubMed2000

Effect of ispaghula husk on the faecal output of bile acids in healthy volunteers.

Faecal bile acids are associated with both colorectal cancer and serum cholesterol levels. We investigate whether dosing with ispaghula husk affects the faecal bile acid weights and concentrations in healthy adults. Sixteen healthy volunteers consumed 7.0 g/day ispaghula husk, containing 5.88 g/day Englyst-determinable dietary fibre, for the middle 8 weeks of a 12-week period. Stool samples were collected, analysed for faecal bile acids and their form and dry weight determined. Correlations between the faecal bile acids, the stool parameters and the dietary intake were tested. Ispaghula husk treatment significantly lowers faecal lithocholic and isolithocholic acids and the weighted ratio of lithocholic acids to deoxycholic acid. These effects revert towards their initial states at the end of the treatment period. These changes in the faecal bile acid profiles indicate a reduction in the hydrophobicity of the bile acids in the enterohepatic circulation.

Adult↗
PubMed2000

Development of a computer software for analysis of SDS-PAGE protein fingerprints of bacterial isolates.

Protein fingerprinting is a widely used technique in epidemiological studies for typing bacterial strains. This study reports the development of a computer based gel analysis system. The system has the capability to analyse SDS-PAGE whole-cell protein profiles using digital image processing techniques. The software incorporates spatial and frequency domain operators for image enhancement, support for geometric correction of images and new algorithms for identification of strain tracks and protein bands. The system also provides facilities for correcting imaging defects for inter-gel comparison, similarity analysis, clustering and pictorial representation of results as a dendrogram. The software is highly interactive, user-friendly and can produce accurate results for differentiation of bacterial strains with minimal overhead of time.

Algorithms↗
PubMed2000

Stevens-Johnson syndrome due to carbamazepine.

Two patients with psychotic disorders who developed Stevens-Johnson Syndrome while on treatment with carbamazepine is reported due to its rarity. Dermatological side-effects of carbamazepine may be more common in psychiatric as compared to neurological patients.

Adult↗
PubMed1999

Transcriptional and post-transcriptional regulation of Na+,K(+)-ATPase alpha isoforms by thyroid hormone in the developing rat brain.

Transcriptional and post-transcriptional events involved in the induction of sodium potassium adenosine triphosphatase (Na+,K(+)-ATPase) by thyroid hormone (T3) were investigated. In vitro transcription of nuclei isolated from cerebra of 5- and 15-day-old normal and hypothyroid rats showed that transcription of all alpha mRNA isoforms (alpha 1, alpha 2 and alpha 3) of Na+,K(+)-ATPase are sensitive to T3. This is evidenced by a 50-70% reduction in the rates of transcription of alpha 1 and alpha 3 mRNA and 20-40% reduction of alpha 2 mRNA in nuclei from hypothyroid cerebra compared with those from normal controls. Preincubation of nuclei from hypothyroid cerebra with T3 prior to transcription also showed an increase in the rates of transcription of these mRNAs. At the post-transcriptional level, T3 enhanced the half life of alpha 3 mRNA by 1.5-fold with no discernible effect on alpha 1 and alpha 2 mRNA.

Aging↗
PubMed1999

Determination of bile acids in human faecal samples using supercritical fluid extraction and high-performance liquid chromatography.

A supercritical fluid extraction (SFE) method for the extraction of bile acids from faeces is described. HPLC with pulsed amperometric detection was used to examine and confirm the recovery of bile acids. The analytes were extracted within a period of 75 min using supercritical carbon dioxide at a pressure of 34.5 MPa and a temperature of 90 degrees C. In developing this method the following parameters were investigated: temperature, pressure, and extraction time. Two alternative methods of sample preparation were also investigated with a view to reducing the overall analysis time. The method was validated for the major primary and secondary bile acids found in faeces. It was found that the overall mean +/- SD recoveries were 102.1+/-7.92%, 111.6+/-9.91%, 112.1+/-9.92% and 113.7+/-9.92% for dry samples and 108.5+/-15.77%, 110.0+/-7.22%, 115.9+/-11.11% and 106.6+/-9.16% for wet samples with respect to cholic, deoxycholic, chenodeoxycholic and lithocholic acid. The SFE is an alternative to the traditional methods available. The extraction is relatively easy to conduct and does not utilise as much glassware, solvents or time.

Bile Acids and Salts↗
PubMed1999

Tubulin and glial fibrillary acidic protein gene expression in developing fetal human brain at midgestation.

Developmental alterations in the expression of glial fibrillary acidic protein (GFAP) and alpha-tubulin were examined at the level of mRNA and protein in human fetal brain between weeks 13-23 of gestation. Except for a transient increase at week 15, GFAP expression in the cytoskeletal (CSK) fraction was low until week 17, when it increased steadily to week 23, corresponding to the phase of glial proliferation. The developmental profile of alpha-tubulin in the CSK fraction displayed a biphasic pattern, with an initial rise between weeks 13-16 coinciding with the early phase of neuroblast multiplication, and a second rise between weeks 17-23 corresponding to the phase of glial proliferation. No significant difference in the spatial distribution of alpha-tubulin was found in different region of brain but GFAP expression varied with a higher level in cerebellum than that in cerebrum at late midgestation.

Brain↗
PubMed1997

Regulation of beta- and gamma-actin mRNA by thyroid hormone in the developing rat brain.

The relative sensitivity of the two isotypes of actin mRNA (beta and gamma) to thyroid hormone (T3) was examined by comparing the steady state levels of these mRNAs with their rates of transcription in cerebra from normal and hypothyroid rats of different ages, covering the period of synaptogenesis (days 1-20 postnatal). Hypothyroidism was associated with a reduction in the steady state level of beta-actin mRNA during the entire period, but levels of gamma-actin mRNA were reduced only during the early phase of synaptogenesis (first week). The rats of transcription of both beta- and gamma-actin mRNAs were stimulated by T3 during the early phase but that of beta-actin mRNAs was relatively more sensitive to T3 than gamma-actin mRNA. The lack of correlation between the rates of transcription of beta- and gamma-actin mRNA at different ages with their corresponding steady-state levels suggests additional post-transcriptional regulation.

Actins↗
PubMed1997

Immunotherapy of lepromin-negative borderline leprosy patients with low-dose Convit vaccine as an adjunct to multidrug therapy; a six-year follow-up study in Calcutta.

The present report, which describes management of lepromin-negative borderline leprosy patients with low-dose Convit vaccine, is an extension of our earlier study on the treatment of lepromatous leprosy patients with low-dose Convit vaccine as an adjunct to multidrug therapy (MDT). The test Group I, consisting of 50 lepromin-negative, borderline leprosy patients, were given low-dose Convit vaccine plus MDT. The control group II consisted of 25 lepromin-negative, borderline leprosy patients given BCG vaccination plus MDT and 25 lepromin-negative, borderline leprosy patients given killed Mycobacterium leprae (human) vaccine plus MDT. The control group III consisted of 50 lepromin-positive, borderline leprosy patients not given any immunostimulation but given only MDT. Depending upon the lepromin unresponsiveness, the patients were given one to four inoculations of the various antileprosy vaccines and were followed up every 3 months for 2 years for clinical, bacteriological and immunological outcome. All patients belonging to the test and control groups showed clinical cure and bacteriological negativity within 2 years. However, immunologic potentiation, assessed by lepromin testing and the leukocyte migration inhibition test (LMIT), was better in the test patients receiving low-dose Convit vaccine plus MDT than in the control patients receiving BCG vaccine plus MDT or killed M. leprae vaccine plus MDT or MDT alone. But the capacity of clearance bacteria (CCB) test from the lepromin granuloma showed poor bacterial clearance in the test patients. However, there was no relapse during 6 years of follow up. Two mid-borderline (BB) patients had severe reversal reactions with lagophthalmos and wrist drop during immunotherapy despite being given low-dose Convit vaccine.

Adult↗
PubMed1996

Differential effects of hypothyroidism on Na-K-ATPase mRNA alpha isoforms in the developing rat brain.

In the developing rat cerebrum, the level of different isoforms of Na-K-ATPase mRNA increases significantly during the first three postnatal weeks, which represent the critical period of synaptogenesis and myelination-the two thyroid hormone-sensitive maturational events. To determine the possible functional relationship of these isoforms with maturational events in the developing brain and their mode of regulation by T3, we have examined the effect of hypothyroidism on the expression of the different alpha-isoforms (alpha 1, alpha 2, and alpha 3) of Na-K-ATPase mRNA covering the first 3 wk of postnatal development. Quantitation of these mRNAs from cerebra of 1-, 5-, 10-, 15-, and 20-d-old normal and hypothyroid rats by Northern blot analysis indicate that alpha 3 mRNA is not only predominantly expressed throughout this entire period of study but also represents the species which is most severely affected in the hypothyroid brain. The relative sensitivity for the expression of these mRNAs to T3 were alpha 3 > alpha 1 > alpha 2. These results, together with the report of predominant expression of the alpha 3 isoform in neuronal cells, suggest specific functional involvement of this isoform with the decisive maturational events in the rat brain. Kinetic studies on in vivo induction of Na-K-ATPase alpha-mRNAs by T3 in the 15-d-old hypothyroid rat shows clear stimulation of all the isoforms within 1 h of the administration of the optimal dose (200 micrograms T3/100 g body wt) suggesting a direct, possibly transcriptional effect of the hormone on the expression of these genes.

Aging↗
PubMed1996

Regulation of actin and tubulin gene expression by thyroid hormone during rat brain development.

In the developing brain the active neurite outgrowth during the early phase of synaptogenesis is associated with a thyroid hormone dependent expression of tubulin and actin. In this study, the molecular mechanism of thyroid hormone (TH) action on actin and tubulin gene expression in the developing rat brain has been investigated by comparing the steady state levels of both mRNAs with their respective rates of transcription in cerebra from normal and hypothyroid animals. The developmental profile of actin as well as tubulin mRNAs in both normal and hypothyroid brains display a biphasic pattern, increasing progressively during the first week after birth and declining thereafter. However, hypothyroidism resulted in a significant reduction in the steady state levels of both mRNAs during the first postnatal week. During the second and third weeks, in contrast to their rapid decline in the normal controls, the corresponding decrease in the hypothyroid cerebra was retarded and prolonged resulting in their higher levels under TH-deficient condition. Kinetics of stimulation of actin and tubulin mRNAs in the 5-day hypothyroid cerebra following injection of the optimal dose of TH (200 micrograms T3/100 g body wt.) demonstrated elevation of both mRNAs within 1 h indicating a possible role of TH at the transcriptional level. In vitro transcription experiments by nuclear run off assay unambiguously confirmed that actin gene transcription is depressed in the hypothyroid cerebra compared to normal control. This reduced rate of transcription could be significantly induced in the hypothyroid cerebra by incubation of hypothyroid nuclei with T3 prior to transcription. In contrast, except for a reduced transcription in 5-day hypothyroid nuclei, no effect on tubulin gene transcription was evident at any other age. Moreover preincubation of hypothyroid nuclei from all three ages with T3 had no stimulatory effect on tubulin gene transcription. Analysis of age related changes in the rates of transcription of actin and tubulin genes with their corresponding steady state mRNA levels in normal and hypothyroid developing brain provides strong evidence that although additional modes of regulation may be operative, transcription represents an important level of control for thyroidal regulation of actin gene expression while tubulin gene expression is primarily regulated at post-transcriptional level.

Actins↗
PubMed1996

Involvement of mercury in platelet aggregation--probable mechanism of action.

Both in vivo and in vitro Hg2+ caused dose dependent inhibition of rat platelet aggregation. However, as low a dose as 88.8 pM Hg2+ could initiate ADP-induced aggregation even in the absence of added calcium. The action of Hg2+ was found to be unaffected by antagonists such as cAMP and theophylline either alone or in combination. Hg2+ induced platelet aggregation was inhibited completely by pre-incubation with aspirin (1 mmol.L-1), but it was ineffective when added after Hg2+. The results also indicate that the normal platelet function is affected by both high and low concentrations of Hg2+.

Adenosine Diphosphate↗
PubMed1995

Accidents in the aluminium smelting industry.

Analysis of the accident records of an aluminium smelting industry, covering about 2,100 employees, over a period of three years, showed a total of 465 accidents of male employees. Out of these, 5 were fatal, 40.86% were from contacts with extreme temperatures, causing burn injury to 42.58%. Hot materials were the agents causing 44.52% of the burn injuries. Molten aluminium constituted 43.96% amongst hot materials. Injury to lower limbs constituted 38.71% and that to upper limbs 36.99%. The accidents occurring to the employees, in the age group of 26-33 years, amounted to 61.72% of the total accidents. The average number of man-days lost per year was 11,153. Average frequency rate of accidents was 30.75 accidents per million man-hours worked. Severity rate of accidents was 2.196 per million man-hours worked. Incident rate per thousand employees was 73.81. Average number of days lost per accidents was 71.95 days and average duration of man-hours between accidents was 32,516. Mean age of the employees, who met with the accidents were 29.53 years. Share of accidents in the second half of each shift was always more than that in the first half, and this average was 66.66%.

Absenteeism↗
PubMed1994

Identification and characterization of a tubulin binding protein in rat brain plasma membrane.

Studies on the interaction of FITC-tubulin and 125I-tubulin with isolated plasma membrane of neural cells and with primary cultures of neuronal (N) and glial (G) cells of rat brain demonstrate the presence of specific, saturable, high affinity tubulin binding sites in these cells. The positive fluorescence of live unfixed primary cultures of N and G cells following incubation with FITC-tubulin indicate that the tubulin binding sites are located on the outer side of the plasma membrane. Such fluorescence was not observed with FITC-BSA, FITC-conalbumin or freshly dissociated cells from rat tissues or established cell lines. Binding of FITC-tubulin or 125I-tubulin is competed only by tubulin and not by other proteins. Scatchard analysis of the binding of 125I-tubulin to purified plasma membrane indicates very high affinity (Kd = 85 nM) with a Bmax of 7.4 pmol/mg protein. The putative tubulin receptor was partially purified by affinity chromatography on tubulin-sepharose column. Immunoprecipitation of the solubilized tubulin-receptor complex followed by SDS-PAGE analysis and autoradiography, revealed the presence of two components of molecular weights 70 and 45 kDa respectively, presumably representing the two nonidentical subunits of the putative receptor. In conjunction with several recent reports indicating the secretion of high molecular weight proteins from cultured neural cells and the ability of tubulin to modulate adenyl cyclase in synaptic membranes these findings suggest that the binding of exogenous tubulin to sites external to the plasma membrane may be involved in signal transduction.

Animals↗
PubMed1994

Thyroidal stimulation of tubulin and actin in rat brain cytoskeleton.

In cultures of neonatal rat brain cells, labeled with 35S-methionine in the presence or absence of triiodothyronine (T3), the hormone promoted a significant enhancement of labeled tubulin and actin in the insoluble fraction (30,000 g pellet) of cell homogenate. To identify the specific sub-cellular fraction associated with this induction, organ cultures of 1 day rat cerebra were labelled with 35S-methionine in the presence and absence of T3 and the insoluble fraction (30,000 g pellet) was subfractionated into mitochondria, plasma membrane and cytoskeleton. Analysis of the labeled proteins by SDS-PAGE, autoradiography and densitometry revealed a T3-induced increase of 50-80% for both tubulin and actin, only in the cytoskeleton fraction without any significant effect on the other fractions. Similar results were obtained when plasma membrane or cytoskeleton were isolated directly from labeled cerebrum by conventional methods instead of fractionating from the 30,000 g pellet. Analysis of relative stimulation of labeled tubulin and actin by T3 in cytoskeleton fraction derived from primary cultures of neuronal (N) and glial (G) cells labeled with 35-methionine show that the stimulatory effect is predominantly on the N cells. Studies on the kinetics of induction of labeled tubulin and actin by T3 in the cytoskeleton fraction prepared from cerebra labeled with 35S-methionine for 2, 8 and 18 hrs revealed no significant difference at 2 hrs; at 8 hrs, an increased incorporation into both tubulin and actin was reproducibly seen in the controls relative to T3-treated samples.(ABSTRACT TRUNCATED AT 250 WORDS)

Actins↗