Search PubMed⌕ Search

Biomedical subjects

A Bhattacharya

Publications and source records attributed to A Bhattacharya.

At least 91 records · Page 5Linked to original sources
PubMed1999

Modulation of dihydropyridine-sensitive calcium channels in Drosophila by a cAMP-mediated pathway.

Drosophila has proved to be a valuable system for studying the structure and function of ion channels. However, relatively little is known about the regulation of ion channels, particularly that of Ca2+ channels, in Drosophila. Physiological and pharmacological differences between invertebrate and mammalian L-type Ca2+ channels raise questions on the extent of conservation of Ca2+ channel modulatory pathways. We have examined the role of cyclic adenosine monophosphate (cAMP) cascade in modulating the dihydropyridine (DHP)-sensitive Ca2+ channels in the larval muscles of Drosophila, using mutations and drugs that disrupt specific steps in this pathway. The L-type (DHP-sensitive) Ca2+ channel current was increased in the dunce mutants, which have high cAMP concentration owing to cAMP-specific phosphodiesterase (PDE) disruption. The current was decreased in the rutabaga mutants, where adenylyl cyclase (AC) activity is altered thereby decreasing the cAMP concentration. The dunce effect was mimicked by 8-Br-cAMP, a cAMP analog, and IBMX, a PDE inhibitor. The rutabaga effect was rescued by forskolin, an AC activator. H-89, an inhibitor of protein kinase-A (PKA), reduced the current and inhibited the effect of 8-Br-cAMP. The data suggest modulation of L-type Ca2+ channels of Drosophila via a cAMP-PKA mediated pathway. While there are differences in L-type channels, as well as in components of cAMP cascade, between Drosophila and vertebrates, main features of the modulatory pathway have been conserved. The data also raise questions on the likely role of DHP-sensitive Ca2+ channel modulation in synaptic plasticity, and learning and memory, processes disrupted by the dnc and the rut mutations.

1-Methyl-3-isobutylxanthine↗
PubMed1999

Development and evaluation of a microprocessor-based ergonomic dosimeter for evaluating carpentry tasks.

This portable and self-contained lightweight microprocessor based Ergonomic Dosimeter is designed to collect continuously postural angles of the torso and the upper arm in the sagittal plane and the number of kneeling activities. Up to 4 h of task performance data can be stored in a non-volatile memory of the dosimeter, which can then be downloaded to a lap-top computer. The portable dosimeter was tested for test-retest reliability, compared with posture data obtained with a computer-based video analysis system and evaluated at a carpenter's apprentices school and at a construction site. The dosimeter was shown to be suitable for collecting posture and kneeling data for a prolonged period at construction sites.

Anthropometry↗
PubMed1999

Lack of a chromosomal copy of the circular rDNA plasmid of Entamoeba histolytica.

A number of small circular DNAs constitute a part of the genome of Entamoeba histolytica. Among them, the 24.5 kb circular DNA encoding rRNA (EhR1) is the most abundant. Pulsed field gel electrophoresis was used to determine if a chromosomal copy of EhR1 exists and what fraction of the total genome is circular. The results show that the chromosomes of E. histolytica are linear, and that no copy of EhR1 could be detected in any of the linear chromosomes.

Animals↗
PubMed1999

Population ecology of Phlebotomus argentipes (Diptera: Psychodidae) in West Bengal, India.

The population abundance of Phlebotomus argentipes Annandale & Brunetti was studied between January 1986 and December 1987 at 2 sites in West Bengal, India, in relation to 8 ecological parameters (air temperature, rainfall, windspeed, relative humidity, soil moisture, soil temperature, soil pH, and soil organic carbon). Sand flies were present throughout the year with minimum abundance in winter months and maximum during monsoon and postmonsoon months. Correlation analysis examined pairwise relationships among the 8 ecological parameters and P. argentipes abundance. Multiple linear regression of sand fly abundance on the 8 parameters showed that average soil temperature and soil moisture, both recorded 1 mo earlier, were associated positively with sand fly abundance. These findings have important implications for Indian kala-azar disease control and prevention. Effective vector management programs are needed most when weather conditions favor increased sand fly abundance, given that greater sand fly abundance increases the likelihood of host-vector contact and the transmission of Leishmania.

Animals↗
PubMed1999

flex, an X-linked female-lethal mutation in Drosophila melanogaster controls the expression of Sex-lethal.

The Sex-lethal (Sxl) gene is required in Drosophila females for sexual differentiation of the soma, for gem cell differentiation and dosage compensation. We have isolated three new alleles of female-lethal-on-X (flex), an X-linked female-lethal mutation and have characterized its function in sex determination. SXL protein is missing in flex/flex embryos, however transcription from both Sxl(Pe), the early Sxl promoter and Sxl(Pm), the late maintenance promoter, is normal in flex homozygotes. In flex/flex embryos, Sxl mRNA is spliced in the male mode. Analysis of flex germline clones shows that it also functions in oogenesis, but in contrast to Sxl mutants that show an early arrest tumorous phenotype, flex mutant egg chambers develop to stage 10. In flex ovarian clones, Sxl RNA is also spliced in the male form. Hence, flex is a sex-specific regulator of Sxl functioning in both the soma and the germline. Genetic interaction studies show that flex does not enhance female lethality of Sxl loss-of-function alleles but it rescues the male-specific lethality of both of the gain-of-function Sxl mutations, Sxl(M1 )and Sxl(M4.) In contrast to mutations in splicing regulators of Sxl, the female lethality of flex is not rescued by either Sxl(M1 )or Sxl(M4). Based on these observations, we propose that flex regulates Sxl at a post-splicing stage and regulates either its translation or the stability of the SXL protein.

Acetylation↗
PubMed1999

Quantitative posturagraphy as an alternative noninvasive tool for alcohol/drug/chemical testing--preliminary thoughts.

This article provides preliminary ideas regarding how the quantitative posturagraphy technique can be used as an alternative noninvasive tool to currently available blood/urine test for alcohol/drug/chemical exposure. It is argued that the urine or blood level of any chemical is highly dependent on the individual's metabolism without providing any insight into individual's task performance abilities under exposure to neurotoxic chemicals. On the other hand, the quantitative posturagraphy if carried out as proposed in this article will provide quantitative data regarding individual's ability to maintain "safe" upright balance while carrying out certain tasks. The proposed evaluation method is simple, portable, quick, and noninvasive and has been found to be sensitive to detecting low level solvent induced modifications in postural stability.

Ethanol↗
PubMed1999

Antiphospholipid antibodies syndrome in 'Stroke in young'.

Antiphospholipid antibodies syndrome has emerged as an important entity responsible for stroke in young. Seven cases of young stroke (< 40 years of age) with mean age of 30.1 years (age range 25-39 years, 2 males and 5 females), who tested positive for antiphospholipid antibodies are being reported. All subjects had completed strokes. Six had arterial ischaemic and one patient had venous stroke. One patient suffered from four episodes, three ischaemic and one intracerebral haemorrhage. Two patients suffered from foetal loss. Generalised tonic clonic seizures occurred in three patients. Deep vein thrombosis was observed in one case. Thrombocytopenia was not observed in any case. All the patients had elevated anticardiolipin antibodies (aCL) IgM or IgG, while Lupus anticoagulant (LA) was elevated in 4 cases. Six cases belonged to primary antiphospholipid antibodies syndrome and one to lupus like illness. Oral anticoagulants were administered to maintain a high intensity international normalized ratio (INR). No recurrences were observed during a follow up period of 6-18 months.

Adult↗
PubMed1999

Antioxidant activity of active tannoid principles of Emblica officinalis (amla).

The antioxidant activity of tannoid active principles of E. officinalis consisting of emblicanin A (37%), emblicanin B (33%), punigluconin (12%) and pedunculagin (14%), was investigated on the basis of their effects on rat brain frontal cortical and striatal concentrations of the oxidative free radical scavenging enzymes, superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX), and lipid peroxidation, in terms of thiobarbituric acid-reactive products. The results were compared with effects induced by deprenyl, a selective monoamine oxidase (MAO) B inhibitor with well documented antioxidant activity. The active tannoids of E. officinalis (EOT), administered in the doses of 5 and 10 mg/kg, i.p., and deprenyl (2 mg/kg, i.p.), induced an increase in both frontal cortical and striatal SOD, CAT and GPX activity, with concomitant decrease in lipid peroxidation in these brain areas when administered once daily for 7 days. Acute single administration of EOT and deprenyl had insignificant effects. The results also indicate that the antioxidant activity of E. officinalis may reside in the tannoids of the fruits of the plant, which have vitamin C-like properties, rather than vitamin C itself.

Animals↗
PubMed1998

Induction of a spectroscopically defined transition by guanidinium hydrochloride on a recombinant calcium binding protein from Entamoeba histolytica.

Sequence analysis and metal ion binding studies reported earlier have established that the calcium binding protein (CaBP) from the parasitic ameboid Entamoeba histolytica protein has four canonical EF hand motifs which bind calcium. Equilibrium denaturation studies on both the apo and the holo forms of this protein indicate the presence of stable transition intermediates at low denaturant concentrations as revealed by the binding of the non-specific hydrophobic dye ANS. Fast reaction kinetics shows that the binding of the Gdn+ ions at or near the Ca2+ sites in the N-terminal domain influences metal ion binding to the sites in the C-terminal domain. Isothermal calorimetric titrations performed using low GdnHCl concentrations reveal the presence of two binding sites of low affinity, both being endothermic in nature. Thus the stabilization of CaBP observed at low GdnHCl concentration represents a native-like intermediate, with the Gdn+ ions mimicking Ca2+ binding at the N-terminal domain of this protein.

Animals↗
PubMed1998

Crystallization and preliminary X-ray studies of a recombinant calcium-binding protein from Entamoeba histolytica.

A calcium-binding protein (CaBP) of Entamoeba histolytica was purified from an E. coli recombinant clone carrying the CaBP gene in a pET-3c expression vector using anion-exchange and size-exclusion chromatography. Examination of the amino-acid sequence of the recombinant protein suggested that it has four independent EF-hand motifs. The protein dissolved in cacodylate buffer was crystallized using the hanging-drop method with 2-methylpentane-2,4-diol (MPD) as the precipitant. X-ray diffraction data have been collected on these crystals using a MAR Research imaging-plate detector system attached to a Rigaku RU200 rotating-anode X-ray generator. The crystals belong to the hexagonal space group P6122 with unit-cell dimensions of a = b = 96.21, c = 65.48 A. Preliminary molecular-replacement computations suggest that the structure of this protein is likely to be similar to that of calmodulin (CAM).

Amino Acid Sequence↗
PubMed1998

The ribosomal DNA plasmids of entamoeba.

In most organisms, the nuclear ribosomal RNA (rRNA) genes are highly repetitive and arranged as tandem repeats on one or more chromosomes. In Entamoeba, however, these genes are located almost exclusively on extrachromosomal circular DNA molecules with no clear evidence so far of a chromosomal copy. Such an uncommon location of rRNA genes may be a direct consequence of cellular physiology, as suggested by studies with Saccharomyces cerevisiae mutants in which the rDNA is extrachromosomal. In this review, Sudha Bhattacharya, Indrani Som and Alok Bhattacharya summarize current knowledge on the structural organization and replication of the Entamoeba rDNA plasmids. Other than the rRNAs encoded by these molecules, no protein-coding genes (including ribosomal protein genes) are found on any of them. They are unique among plasmids in that they do not initiate replication from a fixed origin but use multiple sites dispersed throughout the molecule. Further studies should establish the unique biochemical features of Entamoeba that lead to extrachromosomal rDNA.

Journal Article↗
PubMed1998

Reliability of questionnaire information measuring musculoskeletal symptoms and work histories.

This study was designed to assess the test-retest reliability of a musculoskeletal symptom and work history (MSWH) questionnaire administered to 522 carpenters A 10% subgroup of carpenters completing the original interview was selected for the retest interview. The areas addressed included recall of work-related musculoskeletal symptoms, prior medical conditions, prior injuries, recall of work histories, and psychosocial items. The results show that for these sections of the MSWH questionnaire the observed agreements ranged from 75.5 to 97.0%, and the calculated kappa estimates ranged from 0.46 to 0.77. Injury to body regions, job specialty, and prior medical history had the highest kappa values of K = .70 or greater. Reliability of reporting frequency of job duties such as flooring and finishing was excellent, with kappa = 0.73 (95% confidence interval = 0.66, 0.80). Based on these results, the overall reliability of the MSWH questionnaire is very good.

Adolescent↗
PubMed1998

Asymptomatic methaemoglobinaemia and its implications.

Anaesthetists are well trained to detect subtle skin signs of life-threatening situations such as cyanosis in hypoxia. However, cyanosis resulting from drug-induced, asymptomatic methaemoglobinaemia is rare and is likely to go undetected preoperatively. Patients presenting with asymptomatic methaemoglobinaemia may, therefore, offer a dramatic challenge to the unprepared anaesthetist. We report a case of methaemoglobinaemia secondary to dapsone ingestion that was diagnosed intraoperatively.

Cyanosis↗
PubMed1998

Prevalence of work related musculoskeletal disorders in active union carpenters.

OBJECTIVES: To determine the prevalence and risk factors for work related musculoskeletal disorders among union carpenters. METHODS: A detailed questionnaire on musculoskeletal symptoms and work history was administered to 522 carpenters. The symptom questions assessed if carpenters experienced pain, numbness, or tingling in a particular body region. A subset of this group then received a physical examination of the upper extremities and knees. RESULTS: The study group was primarily white (94.9%) and male (97.8%) with a mean age of 42.3 years. The highest prevalence of work related musculoskeletal disorders cases by carpentry specialty ranged from 20%-24% for those doing drywall or ceiling, finishing or framing, and the building of concrete forms. Generally, as duration of employment increased, the prevalence of symptoms increased. An adjusted logistic regression analysis showed that the group with the longest (> or = 20 years) duration of employment in carpentry was significantly associated with work related musculoskeletal disorders of the shoulders (odds ratio (OR) 3.2, 95% confidence interval (95% CI) 1.1 to 8.9), hands or wrists (OR 3.1, 95% CI 1.1 to 8.4), and knees (OR 3.5, 95% CI 1.3 to 9.2). Also, analyses showed that carpenters who reported that they had little or no influence over their work schedule had significant increases of work related musculoskeletal disorders of the shoulders, hips, and knees with ORs of 1.9 (95% CI 1.1 to 3.2), 2.9 (95% CI 1.1 to 7.2), and 2.3 (95% CI 1.2 to 4.1), respectively. Feeling exhausted at the end of day was also a significant risk factor for work related musculoskeletal disorders of the knee (OR 1.8, 95% CI 1.1 to 3.1). Upper extremity disorders were the most prevalent work related musculoskeletal disorders reported among all carpenters. Drywall or ceiling activities involve a considerable amount of repetitive motion and awkward postures often with arms raised holding heavy dry walls in place, whereas form work is notable for extensive lumbar flexion and had the two highest rates of work related musculoskeletal disorders. The psychosocial element of job control was associated with both upper and lower extremity disorders. These union carpenters, who were relatively young, already were experiencing considerable work related physical problems. CONCLUSION: This study supports the need for vigilant ergonomic intervention at job sites and early ergonomic education as an integral part of apprenticeship school training to ensure that carpenters remain fit and healthy throughout their working lifetime.

Adult↗
PubMed1998

Effect of nutritional status on vecuronium induced neuromuscular blockade.

Based on simple clinical and biochemical parameters of nutritional status, seventy adult patients scheduled for elective surgery under general anaesthesia were categorized as having normal nutrition, mild, moderate or severe malnutrition or obesity. Under anaesthesia, evoked responses on train-of-four nerve stimulation were recorded every 15 seconds on a mechanomyograph. Vecuronium 0.1 mg.kg-1 was used to achieve neuromuscular blockade. Compared with patients having normal nutrition, the time to onset of action was significantly prolonged in the moderate and severely malnourished groups; the time to no response on train-of-four stimulation was delayed only in severely malnourished groups (P < 0.001). The duration of action of the initial dose was shorter in the moderate and severely malnourished groups. The obese group had an earlier onset of action and a longer duration of action compared with patients of normal nutrition (P < 0.001). No significant difference in recovery time to a train-of-four ratio of 0.70 was observed between the malnourished and patients with normal nutrition. Malnutrition has a marked effect on vecuronium-induced neuromuscular blockade.

Adolescent↗