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Biomedical subjects

P Chattopadhyay

Publications and source records attributed to P Chattopadhyay.

At least 19 recordsLinked to original sources
PubMed2002

Genetic polymorphism at nine microsatellite loci in four high altitude Himalayan desert human populations.

Allele frequencies for the nine STR loci of Profiler Plus STR markers were analyzed in 307 healthy unrelated individuals belonging to four predominant highly important endogamous population groups of Ladakh. The studied loci are found highly informative in human identification and understanding history of peopling of India. This is the first report on DNA Markers on any high altitude desert human population group.

Alleles↗
PubMed2002

A new improved method for extraction of DNA from teeth for the analysis of hypervariable loci.

A new method for better recovery of DNA suitable for amplification of hypervariable loci from fragments of teeth, consisting of two steps-scraping and aspiration, and extensive decalcification-is reported. Higher yields of high molecular weight DNA were obtained from the root, pulp, and crown of all kinds of 120 teeth, irrespective of gender, age, and source of teeth. HLA DQA1, 5 poly markers (LDLR, GYPA, HBGG, D7S8, and Gc), and other 12 short tandem repeat loci (HPRTB, F13B, LPL, D13S317, D7S820, D5S818, D21S11, D18S51, FGA, D8S1179, D3S1358, and vWA) could be successfully amplified and typed from recovered DNA.

Adolescent↗
PubMed2002

Patterns of genetic diversity at the nine forensically approved STR loci in the Indian populations.

Genetic diversity at the nine short tandem repeat (STR) loci, which are universally approved and widely used for forensic investigations, has been studied among nine Indian populations with diverse ethnic, linguistic, and geographic backgrounds. The nine STR loci were profiled on 902 individuals using fluorescent detection methods on an ABI377 System, with the aid of an Amp-F1 Profiler Plus Kit. The studied populations include two upper castes, Brahmin and Kayastha; a tribe, Garo, from West Bengal; a Hindu caste, Meitei, with historical links to Bengal Brahmins; a migrant group of Muslims; three tribal groups, Naga, Kuki and Hmar, from Manipur in northeast India; and a middle-ranking caste, Golla, who are seminomadic herders from Andhra Pradesh. Gene diversity analysis suggests that the average heterozygosity is uniformly high (>0.8) in the studied populations, with the coefficient of gene differentiation at 0.050 +/- 0.0054. Both neighbor-joining (NJ) and unweighted pair group method with arithmetic mean (UPGMA) trees based on DA distances bring out distinct clusters that are consistent with ethnic, linguistic, and/or geographic backgrounds of the populations. The fit of the Harpending and Ward model of regression of average heterozygosity on the gene frequency centroid is found to be good, and the observed outliers are consistent with the population structure and history of the studied populations. Our study suggests that the nine STR loci, used so far mostly for forensic investigations, can be used fruitfully for microevolutionary studies as well, and for reconstructing the phylogenetic history of human populations, at least at the local level.

Alleles↗
PubMed2001

Production of griseofulvin nanoparticles using supercritical CO(2) antisolvent with enhanced mass transfer.

Griseofulvin (GF) is a poor water soluble, antifungal agent. The bioavailability of the drug and its absorption from the gastrointestinal tract can be greatly improved by particle size reduction. In this work, supercritical antisolvent precipitation with enhanced mass transfer (SAS-EM) has been proposed for the production of GF nanoparticles. SAS-EM is a modification of the currently existing supercritical antisolvent (SAS) precipitation technique and also utilizes supercritical CO(2) as the antisolvent. In SAS-EM however, the solution jet is deflected by a surface vibrating at an ultrasonic frequency that atomizes the jet into small micro droplets. Further, the ultrasound field generated by the vibrating surface inside the supercritical media enhances mass transfer and prevents agglomeration due to increased mixing. GF nanoparticles of different sizes and morphologies have been obtained by varying the vibration intensity of the deflecting surface, which in turn is adjusted by changing the power supply to the attached ultrasound transducer. GF nanoparticles as low as 130 nm in size have been obtained corresponding to a power supply of 180 W. The effect of using different solvents on the size and morphology of the particles has also been studied.

Algorithms↗
PubMed2001

Distribution of alleles of three tetrameric STR loci HUMHPRTB, HUMF13B, HUMLPL and other six PCR based loci HLA DQA1, LDLR, GYPA, HBGG, D7S8, Gc in eight predominant populations of India.

Allele frequencies for the six PCR based loci HLA DQA1, LDLR, GYPA, HBGG, D&S8, Gc, and three STR loci HUMHPRTB, HUMF13B & HUMLPL were analyzed in 624 healthy unrelated individuals belonging to eight important population groups of two major ethnic populations: Indo-Caucasian and Indo-Mongoloid.

Alleles↗
PubMed2001

Effect of a rigid nonpolar solute on the splay, bend elastic constants, and on rotational viscosity coefficient of 4,4'-n-octyl-cyanobiphenyl.

The effect of a rigid nonpolar nonmesogenic solute "biphenyl," that is, C6H5-C6H5 on the splay and bend elastic constants and on the rotational viscosity coefficient of 4,4'-n-octyl-cyanobiphenyl is reported. The experiments involve the measurement of the voltage dependence of the capacitance of a cell filled with the mixture. Anomalous behavior of both K11 and Deltaepsilon near the N-S(A) transition have been observed.

Journal Article↗
PubMed2001

Analysis of sintered products of iron ore fines by flame atomic absorption spectrometry using a matrix modifier.

A very precise and accurate method for chemical analysis of sintered products (from iron ore fines in "pot grate furnace") is discussed. A matrix modifier/buffer (a mixture of KCl, tartaric acid, HCl and H2SO4) is used to prevent interference of iron in the determination of calcium and magnesium by flame atomic absorption spectrometry. Also, an EDTA titration method is recommended for calcium and magnesium after separating iron in the form of mixed oxides by ammonia-ammonium chloride buffer. Statistical data for a series of experiments are presented and precision values are found to be comparable with those of conventional methods used for complex metallurgical products. For the majority of cases, the agreement between the two methods is extremely good. A slight deviation has been noted in a few samples which may be overcome by a more thorough sampling prior to analysis.

Journal Article↗
PubMed2001

Genetic heterogeneity and alterations in chromosome 9 loci in a localized region of a functional pituitary adenoma.

The molecular alterations reported in pituitary adenomas include mutations at the G(s)alpha in somatotrophinomas, and hypermethylation of the p16 tumor suppressor gene. There are, however, no reports of genomic instability or intratumor genetic heterogeneity in pituitary adenomas. We have studied the microsatellite loci on the short arm of chromosome 9 (9p) and the DNA fingerprinting pattern, of adjacent compartments, about 2 mm across, in a functional chromophobe pituitary adenoma secreting growth hormone and prolactin. The microsatellite loci were studied by PCR amplification using locus specific primers, while the DNA fingerprinting pattern was studied by randomly amplified polymorphic DNA (RAPD) analysis. Normal leukocyte DNA was taken as control. Only one compartment (Ta) showed alterations in several of the microsatellite loci and in the RAPD pattern vis a vis corresponding normal DNA and also the other two compartments of the tumor. This provides evidence for the localized nature of genomic instability in this tumor.

Adenoma↗
PubMed2001

Examining the effects of work externalization through the lens of social identity theory.

This study examines whether dissimilarity among employees that is based on their work status (i.e., whether they are temporary or internal workers) influences their organization-based self-esteem, their trust in and attraction toward their peers, and their altruism. A model that is based on social identity theory posits that work-status dissimilarity negatively influences each outcome variable and that the strength of this relationship varies depending on whether employees have temporary or internal status and the composition of their work groups. Results that are based on a survey of 326 employees (189 internal and 137 temporary) from 34 work groups, belonging to 2 organizations, indicate that work-status dissimilarity has a systematic negative effect only on outcomes related to internal workers when they work in temporary-worker-dominated groups.

Adult↗
PubMed2000

Synthesis and structural characterization of a Re(V) complex with a 2N1S donor and the radiochemical behavior of its Tc analog.

A rhenium(V) complex with 2-(2-pyridylmethylthio)-aniline has been synthesized and characterized by UV-VIS absorption, IR, MS and X-ray crystallography. The complex contains a ReO3+ moiety and the amine compound, acting as a monobasic tridentate(NSN) ligand. The chemical behavior of its technetium analog has been studied radioanalytically by solvent extraction, TLC, electrophoresis and HPLC using 99mTc tracer.

Crystallography, X-Ray↗
PubMed2000

Structural requirement for the two-step dimerization of human immunodeficiency virus type 1 genome.

Generation of RNA dimeric form of the human immunodeficiency virus type 1 (HIV-1) genome is crucial for viral replication. The dimerization initiation site (DIS) has been identified as a primary sequence that can form a stem-loop structure with a self-complementary sequence in the loop and a bulge in the stem. It has been reported that HIV-1 RNA fragments containing the DIS form two types of dimers, loose dimers and tight dimers. The loose dimers are spontaneously generated at the physiological temperature and converted into tight dimers by the addition of nucleocapsid protein NCp7. To know the biochemical process in this two-step dimerization reaction, we chemically synthesized a 39-mer RNA covering the entire DIS sequence and also a 23-mer RNA covering the self-complementary loop and its flanking stem within the DIS. Electrophoretic dimerization assays demonstrated that the 39-mer RNA reproduced the two-step dimerization process, whereas the 23-mer RNA immediately formed the tight dimer. Furthermore, deletion of the bulge from the 39-mer RNA prevented the NCp7-assisted tight-dimer formation. Therefore, the whole DIS sequence is necessary and sufficient for the two-step dimerization. Our data suggested that the bulge region regulates the stability of the stem and guides the DIS to the two-step dimerization process.

Capsid↗
PubMed2000

Extensive intra-tumor heterogeneity in primary human glial tumors as a result of locus non-specific genomic alterations.

Genomic changes are a hallmark of the neoplastic process. These range from alterations at specific loci and defined karyotypic changes which influence tumor behavior to generalized alterations exemplified by microsatellite instability. Generalized genomic changes within a tumor would be evidence in favor of the mutator hypothesis which postulates a role for such extensive changes during tumorigenesis. In this report, we have used the DNA fingerprinting technique of randomly amplified polymorphic DNA (RAPD) analysis to study genomic alterations within primary human astrocytic tumors (gliomas) in a locus non-specific manner. The RAPD fingerprinting profile of consecutive segments of tumors 2 mm across was studied; 17 astrocytic (high- and low-grade) tumors were sectioned end to end. Tissue from 50 consecutive sections, 40 microm thick (total 2 mm across), was pooled and taken to be a tumor compartment. DNA was subjected to RAPD amplification by 15 random 10-mer primers. A tumor segment was taken to have a DNA fingerprinting pattern different from others in the same specimen when its RAPD profile differed from others by at least one band of one RAPD reaction. All but one of the tumors showed compartments with a unique genetic profile, indicating genomic instability leading to widespread intra-tumor genetic heterogeneity. Eight tumors were also studied for loss of heterozygosity (LOH) of the p53 and D17S379 loci in the different segments as examples of alteration of specific tumor influencing loci. Three showed LOH of p53, which was limited to only one compartment of each tumor. The extensive intra-tumor genetic instability detected in this study is suggestive of the overall high rate of change in the genomes of tumors including those of a lower grade. It is hypothesized that some of these altered clones, which manifest as zones of heterogeneity in a solid tumor, may accumulate changes at loci known to influence tumor behavior, and thus clinical outcome.

Brain Neoplasms↗
PubMed1999

An NMR and mutational analysis of an RNA pseudoknot of Escherichia coli tmRNA involved in trans-translation.

Transfer-messenger RNA (tmRNA) is a unique molecule that combines properties from both tRNA and mRNA, and facilitates a novel translation reaction termed trans -translation. According to phylogenetic sequence analysis among various bacteria and chemical probing analysis, the secondary structure of the 350-400 nt RNA is commonly characterized by a tRNA-like structure, and four pseudoknots with different sizes. A mutational analysis using a number of Escherichia coli tmRNA variants as well as a chemical probing analysis has recently demonstrated not only the presence of the smallest pseudoknot, PK1, upstream of the internal coding region, but also its direct implication in trans -translation. Here, NMR methods were used to investigate the structure of the 31 nt pseudoknot PK1 and its 11 mutants in which nucleotide substitutions are introduced into each of two stems or the linking loops. NMR results provide evidence that the PK1 RNA is folded into a pseudoknot structure in the presence of Mg(2+). Imino proton resonances were observed consistent with formation of two helical stem regions and these stems stacked to each other as often seen in pseudoknot structures, in spite of the existence of three intervening nucleo-tides, loop 3, between the stems. Structural instability of the pseudoknot structure, even in the presence of Mg(2+), was found in the PK1 mutants except in the loop 3 mutants which still maintained the pseudoknot folding. These results together with their biological activities indicate that trans -translation requires the pseudoknot structure stabilized by Mg(2+)and specific residues G61 and G62 in loop 3.

Base Pairing↗
PubMed1999

Evaluation of surrogate markers of impending death in the galactosamine-sensitized murine model of bacterial endotoxemia.

BACKGROUND AND PURPOSE: When evaluating vaccines for efficacy against gram-negative endotoxemia, the challenge has historically required death of a large percentage of test subjects. We attempted to identify surrogate markers of impending death to allow for early euthanasia without interfering with experimental data collection. METHODS: Galactosamine-sensitized mice (n = 140) were inoculated intraperitoneally with various dosages of endotoxin, and development of clinical signs of disease--body temperature, body weight, hunched posture, ruffled coat, inability to ambulate, and loss of consciousness--was evaluated. RESULTS: Wide fluctuations in body temperature (+/- 4 degrees C) were observed in survivors and nonsurvivors. Posture, coat, and body weight were not accurate predictors of death. Only inability to ambulate, with a positive predictive value of 100% (11 of 11), accurately predicted death in the experimental mice of this study. CONCLUSION: Using this surrogate marker, loss of ability to ambulate, 11 of 13 mice that developed this sign could have been euthanized early, preventing anywhere from 2 to 22 h of potential distress prior to death.

Animals↗
PubMed1998

Comparison of antibody and albumin catalyzed hydrolysis of steroidal p-nitrophenylcarbonates.

A monoclonal antibody (MAb) was produced against the p-nitrophenylphosphate derivative of 3 alpha, 5 beta-lithocholic acid, a transition-state analog for hydrolysis of a steroidal p-nitrophenylcarbonate. The indicated reaction was catalyzed by this Ab with kinetic constants kcat = 4.0 x 10(-2)/min and K(m) = 3.3 microM at pH 9.0 and 35 degrees C. The Ab also hydrolyzed the isomeric p-nitrophenylcarbonate of 3 beta, 5 beta-lithocholic acid with kcat = 8.4 x 10(-2)/min and K(m) = 1.0 microM. Bovine serum albumin (BSA) was found to catalyze the same reactions with similar turnover rates and Michaelis constants of 15 and 14 microM, respectively. Although the BSA-catalyzed reaction was only weakly inhibited by the phosphate ester TSA (IC50 ca. 40 microM), the Ab-catalyzed reaction was completely inhibited at less than 1 microM of the TSA. The relative rates and efficiencies of the MAb-catalyzed and BSA-catalyzed reactions are discussed in the context of the hydrophobic sites and intrinsic reactivity of the protein surfaces, and the induction of groups on the Ab to enhance the enzymatic function.

Animals↗