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Biomedical subjects

D Bhattacharya

Publications and source records attributed to D Bhattacharya.

At least 73 records · Page 4Linked to original sources
PubMed1994

Group I introns are inherited through common ancestry in the nuclear-encoded rRNA of Zygnematales (Charophyceae).

Group I introns are found in organellar genomes, in the genomes of eubacteria and phages, and in nuclear-encoded rRNAs. The origin and distribution of nuclear-encoded rRNA group I introns are not understood. To elucidate their evolutionary relationships, we analyzed diverse nuclear-encoded small-subunit rRNA group I introns including nine sequences from the green-algal order Zygnematales (Charophyceae). Phylogenetic analyses of group I introns and rRNA coding regions suggest that lateral transfers have occurred in the evolutionary history of group I introns and that, after transfer, some of these elements may form stable components of the host-cell nuclear genomes. The Zygnematales introns, which share a common insertion site (position 1506 relative to the Escherichia coli small-subunit rRNA), form one subfamily of group I introns that has, after its origin, been inherited through common ancestry. Since the first Zygnematales appear in the middle Devonian within the fossil record, the "1506" group I intron presumably has been a stable component of the Zygnematales small-subunit rRNA coding region for 350-400 million years.

Base Sequence↗
PubMed1994

Sequence analysis of duplicated actin genes in Lagenidium giganteum and Pythium irregulare (Oomycota).

Southern analysis of genomic DNA identified multiple-copy actin gene families in Lagenidium giganteum and Pythium irregulare (Oomycota). Polymerase chain reaction (PCR) protocols were used to amplify members of these actin gene families. Sequence analysis of genomic coding regions demonstrated five unique actin sequences in L. giganteum (Lg-Ac1, 2, 3, 4, 5) and four unique actin sequences in P. irregulare (Pi-Ac1, 2, 3, 4); none were interrupted by introns. Maximum parsimony analysis of the coding regions demonstrated a close phylogenetic relationship between oomycetes and the chromophyte alga Costaria costata. Three types of actin coding regions were identified in the chromophyte/oomycete lineage. The type 1 actin is the single-copy coding region found in C. costata. The type 2 and type 3 actins are found in the oomycetes and are the result of a gene duplication which occurred soon after the divergence of the oomycetes from the chromophyte algae. The type 2 coding regions are the single-copy sequence of Phytophthora megasperma, the Phytophthora infestans actB gene, Lg-Ac5 and Pi-Ac2. The type 3 coding regions are the single-copy sequence of Achlya bisexualis, the P. infestans actA gene, Lg-Ac1, 2, 3, 4 and Pi-Ac1, 3, 4.

Actins↗
PubMed1994

Clinical evaluation of purified vero-cell rabies vaccine in patients bitten by rabid animals in India.

Fifty-five individuals bitten by rabid animals were administered purified vero-cell rabies vaccine (PVRV) at WHO Collaborative Centre for Rabies Epidemiology for South-East Asia at National Institute of Communicable Diseases, Delhi to test its immunogenicity, inocuity, safety and clinical efficacy. Fifty-two (94.5 per cent) of these individuals underwent complete course of treatment. Sera samples collected prior to the commencement of treatment showed all these persons to be sero-negative for antibody against Rabies virus. However mean titre of 2.44 I.U./ml, 7.76 I.U./ml and 10.77 I.U./ml were detected after third, fourth and sixth injections, respectively of PVRV. Persistance of protective titres of this antibody could be demonstrated even after 15 months of treatment. Of 327 inoculations, local and general reactions were observed after 10.6 per cent inoculations. All these cases were followed up for periods between 7 and 25 months and were, alive and healthy till the end of observation period, thereby proving the efficacy of the vaccine in preventing rabies.

Adolescent↗
PubMed1994

Immunogenicity and feasibility of purified chick embryo cell vaccine.

Two hundred seventy-one children reported at the WHO Collaborative Centre for Rabies Epidemiology for South-East Asia at National Institute of Communicable Diseases, Delhi, for advice and antirabies antibody assessment after post-exposure prophylaxis with purified chick embryo cell (PCEC) antirabies vaccine from January 1986 to October 1992. Vaccine was very well tolerated by these children and only 7% complained about mild to moderate side reactions like pain, induration, fever or rash. On an average, every year 50-55 children had reported at this Centre after post-exposure vaccination with PCEC vaccine excepting years 1986 and 1987. One hundred and forty-four children underwent complete course of post-exposure prophylaxis, i.e., 5 or 6 doses on day 0, 3, 7, 14, 30 and 90 (optional) of PCEC vaccine were administered, forty-three (43) children received 4 doses on day 0, 7, 14 and 30 (day 3 dose was omitted) and eighty-four (84) children received 2 to 3 doses as the biting animals were alive for 10 days in these cases. Two hundred and twenty-nine children (84.5%) were bitten by dogs and in 10%, the dog was proven rabid by laboratory examination of dog brain. One hundred and forty-nine (55%) had Class III bite. Serological response, i.e., antirabies antibody titre in all these children were satisfactory (> 0.5 IU/ml) with mean titre of 1.98 IU/ml irrespective of doses of PCEC vaccine administered. No vaccine failure was observed in this study.

Animals↗
PubMed1993

Molecular cloning and evolutionary analysis of the calcium-modulated contractile protein, centrin, in green algae and land plants.

Centrin (= caltractin) is a ubiquitous, cytoskeletal protein which is a member of the EF-hand superfamily of calcium-binding proteins. A centrin-coding cDNA was isolated and characterized from the prasinophyte green alga Scherffelia dubia. Centrin PCR amplification primers were used to isolate partial, homologous cDNA sequences from the green algae Tetraselmis striata and Spermatozopsis similis. Annealing analyses suggested that centrin is a single-copy-coding region in T. striata and S. similis and other green algae studied. Centrin-coding regions from S. dubia, S. similis and T. striata encode four colinear EF-hand domains which putatively bind calcium. Phylogenetic analyses, including homologous sequences from Chlamydomonas reinhardtii and the land plant Atriplex nummularia, demonstrate that the domains of centrins are congruent and arose from the two-fold duplication of an ancestral EF hand with Domains 1+3 and Domains 2+4 clustering. The domains of centrins are also congruent with those of calmodulins demonstrating that, like calmodulin, centrin is an ancient protein which arose within the ancestor of all eukaryotes via gene duplication. Phylogenetic relationships inferred from centrin-coding region comparisons mirror results of small subunit ribosomal RNA sequence analyses suggesting that centrin-coding regions are useful evolutionary markers within the green algae.

Amino Acid Sequence↗
PubMed1993

Isolation and molecular phylogenetic analysis of actin-coding regions from Emiliania huxleyi, a Prymnesiophyte alga, by reverse transcriptase and PCR methods.

Reverse transcriptase and polymerase chain reaction methods were used to amplify and clone actin cDNAs from the chlorophylls a + C-containing unicellular alga, Emiliania huxleyi (Prymnesiophyta). Actins in E. huxleyi are defined by a gene family containing at least six distinct coding regions that were derived from relatively recent gene duplications. Five of the coding regions (types 1, 2, and 4-6) varied only among synonymous codons. A nonsynonomous change in a sixth coding region (type 3 actin) produced a serine-to-phenylalanine replacement. The G + C composition of third positions in E. huxleyi actin genes is 98%, which contrasts with the mean value of 50% G + C content for first and second positions. Distance-matrix and parsimony analyses of actin genes identified the prymnesiophytes as a photosynthetic lineage that is not already related to other eukaryotic algal groups.

Actins↗
PubMed1993

Critique of zero population growth theory.

This is a critique of widely held theories concerning the relationship between population growth and economic development. "The central purpose of this paper is to critically analyse the zero population growth movement. The hypotheses of Neo-Malthusian theory or Zero Population Growth and the concept of Population Bomb will be briefly stated in Section 1. Section 2 will discuss the theory of demographic transition. Section 3 will critically examine the validity of the Neo-Malthusian theory of population growth. Our conclusions and recommendations will be stated in Section 4." The author's main contention is that overconsumption in developed countries is the major cause of the deterioration of the environment rather than overpopulation in the developing countries.

Conservation of Natural Resources↗
PubMed1992

An enzyme immunoassay of phaseolinone and its application in estimation of the amount of toxin in Macrophomina phaseolina-infected seeds.

A microtiter plate-based enzyme immunoassay has been developed for phaseolinone, a phytotoxin isolated from the culture filtrate of the plant-pathogenic fungus Macrophomina phaseolina (Tassi) Goid. The smallest amount of phaseolinone detectable by the method is 5 pg per well. The method is validated by comparison with high-performance liquid chromatography and used to confirm and estimate phaseolinone production in seeds infected with the fungus. The degree of seed inhibition correlated well with the amount of toxin produced in infected seeds, 50% inhibition being observed at a toxin concentration of 0.60 micrograms/g of wet tissue.

Chromatography, High Pressure Liquid↗
PubMed1992

Evaluation of indirect immunofluorescent antibody test for detection of IgM specific antibodies in malaria.

Indirect immunofluorescent antibody test using Plasmodium falciparum antigen from in vitro culture was evaluated for detecting IgM antibodies in order to determine the feasibility of its application in serodiagnosis of malaria. Test was compared with the already adapted IgG-IIF test using the same antigen. It was found that none of the healthy controls and slide negative fever cases had malaria IgM antibodies whereas 8 per cent of healthy controls and 49.01 per cent of the slide negative fever cases had malaria IgG antibodies. The sensitivity of IgM-IIF test was 94.68 per cent and that of IgG-IIF test was 96.81 per cent. IgM antibodies could be detected very early even on the first day of fever and titre rose gradually with increasing number of days of illness before institution of treatment. The IgM antibodies, being short lasting are able to reflect recent infection. The test although highly sensitive and specific is laborious and expensive. Therefore, it may be used as a serodiagnostic test in advanced laboratories only for confirmation of selected slide negative cases.

Animals↗
PubMed1991

Molecular phylogenetic analysis of actin genic regions from Achlya bisexualis (Oomycota) and Costaria costata (Chromophyta).

Actin genic regions were isolated and characterized from the heterokont-flagellated protists, Achlya bisexualis (Oomycota) and Costaria costata (Chromophyta). Restriction enzyme and cloning experiments suggested that the genes are present in a single copy and sequence determinations revealed the existence of two introns in the C. costata actin genic region. Phylogenetic analyses of actin genic regions using distance matrix and maximum parsimony methods confirmed the close evolutionary relationship of A. bisexualis and C. costata suggested by ribosomal DNA (rDNA) sequence comparisons and reproductive cell ultrastructure. The higher fungi, green plants, and animals were seen as monophyletic groups; however, a precise order of branching for these assemblages could not be determined. Phylogentic frameworks inferred from comparisons of rRNAs were used to assess rates of evolution in actin genic regions of diverse eukaryotes. Actin genic regions had nonuniform rates of nucleotide substitution in different lineages. Comparison of rates of actin and rDNA sequence divergence indicated that actin genic regions evolve 2.0 and 5.3 times faster in higher fungi and flowering plants, respectively, than their rDNA sequences. Conversely, animal actins evolve at approximately one-fifth the rate of their rDNA sequences.

Actins↗
PubMed1991

Comparison between indirect fluorescent antibody and Weil-Felix tests for detecting antibodies against rickettsia.

Comparative evaluation of indirect fluorescent antibody test (IFAT) and Weil-Felix test (WFT) was carried out for detecting rickettsial antibodies in 102 patients with pyrexia of unknown origin (P.U.O.), 20 brucellosis cases and 20 normal healthy controls (N.H.C.). Of 102 sera of cases with P.U.O., antibodies against rickettsia could be detected in 11 (10.7 per cent) cases by IFAT and in 10 (9.8 per cent) cases by WFT, but amongst these 10 sera, antibodies could be detected only in six by IFAT. All 20 brucella positive sera were negative for rickettsia by IFAT but by WFT in 6 sera antibodies against rickettsia could be detected and 20 N.H.C. sera were negative by both the tests. Thus the advantages of IFAT over WFT in detecting antibodies against rickettsia in terms of sensitivity and specificity make it a more reliable test.

Agglutination Tests↗
PubMed1988

A general procedure for generation of curved DNA molecules.

A general method for generation of base-pairs in a curved DNA structure, for any prescribed values of helical parameters--unit rise (h), unit twist (theta), wedge roll (theta R) and wedge tilt (theta T), propeller twist (theta p) and displacement (D) is described. Its application for generation of uniform as well curved structures is also illustrated with some representative examples. An interesting relationship is observed between helical twist (theta), base-pair parameters theta x, theta y and the wedge parameters theta R, theta T, which has important consequences for the description and estimation of DNA curvature.

Algorithms↗