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Biomedical subjects

R Trivedi

Publications and source records attributed to R Trivedi.

At least 37 records · Page 2Linked to original sources
PubMed2004

Deciphering diversity in populations of various linguistic and ethnic affiliations of different geographical regions of India: analysis based on 15 microsatellite markers.

The extent of genetic polymorphism at fifteen autosomal microsatellite markers in 54 ethnically, linguistically and geographically diverse human populations of India was studied to decipher intrapopulation diversity. The parameters used to quantify intrapopulation diversity were average allele diversity, average heterozygosity, allele range (base pairs), and number of alleles. Multilocus genotype frequencies calculated for selected populations were utilized for testing conformity with the assumption of Hardy-Weinberg equilibrium. The exact test values, after Bonferroni correction, showed significant deviation amongst Gowda (vWA, Penta E); Dhangar, Satnami and Gounder (D8S1179); Hmar (FGA); Kuki and Balti (vWA) groups. Relatively low number of alleles and allelic diversity (base-pairs size) had been observed in populations of central India as compared with southern and northern regions of the country. The communities of Indo-Caucasoid ethnic origin and Indo-European linguistic family (Kshatriya of Uttar Pradesh) showed highest allelic diversity, as well as rare alleles, not reported in any other Indian populations. Analysis based on average heterozygosity was also found to be lowest among the populations of central India (0.729) and highest among the populations from north (0.777) and west (0.784) regions of the country, having Indo-Caucasoid ethnic origin and Austro-Asiatic linguistic affiliation. The maximum power of discrimination (85%-89%) had been observed at loci FGA, Penta E, D18S51 and D21S11, suggested high intrapopulation diversity in India. Genetic diversity revealed by STR markers was consistent with the known demographic histories of populations. Thus, the present study clearly demonstrated that the intrapopulation diversity is not only present at the national level, but also within smaller geographical regions of the country. This is the first attempt to understand the extent of diversity within populations of India at such a large scale at genomic level.

Alleles↗
PubMed2004

Conventional digital subtraction x-ray angiography versus magnetic resonance angiography in the evaluation of carotid disease: patient satisfaction and preferences.

AIM: To compare conventional digital subtraction x-ray angiography (DSA) and contrast-enhanced magnetic resonance angiography (MRA) of the carotid arteries in terms of patient satisfaction and preferences. METHODS: One hundred and sixty-seven patients with symptomatic carotid artery disease, who underwent both DSA and MRA, were prospectively recruited in this study. Patients' perceptions of each method were assessed by the use of a questionnaire after each procedure. Main outcome measures were anxiety, pain, satisfaction rate and patient preferences. RESULTS: DSA generated more anxiety and pain during the procedure, but the severity of these ill-effects was mild. Satisfaction rates for each method were similar. More patients were, however, willing to have a repeat MRA compared with DSA (67 versus 41%). The majority of patients (62%) preferred MRA over DSA (31%). The shorter MRA imaging time was found to be a significant factor in patients' acceptance of the technique. The main reasons cited by patients for their dislike of a particular procedure was noise and claustrophobia for MRA and invasiveness, pain and post-procedural bed rest for DSA. CONCLUSIONS: MRA is the method that is preferred by the majority of patients, although the actual disutility of DSA may be small. Assuming equal diagnostic accuracy, our data supports replacement of DSA by MRA for routine carotid imaging.

Adult↗
PubMed2004

Genetic diversity at 15 fluorescent-labeled short tandem repeat loci in the Patel and other communities of Gujarat, India.

Thirteen tetranucleotide and 2 pentanucleotide repeat units were analyzed in 120 unrelated individuals of Patel and other communities of Gujarat, India. Allele frequency data obtained from the analysis of 15 short tandem repeat markers of the population were found to be satisfying Hardy-Weinberg equilibrium, with marginal deviations. Departures from Hardy-Weinberg equilibrium were observed in Patel communities at locus vWA and for that of the other communities at locus D7S820 and at locus TPOX. The power of discrimination values on an average fall within the range of 0.718 and 0.870, with deviations at locus D3S1358 showing a value of 0.400 for Patels. The value ranged between 0.709 and 0.869, with slight variations among the studied alleles in the other group. Thus, the 15 markers selected for this study were found to be highly suitable in human identification and for providing information on genetic polymorphism of the population of Gujarat.

DNA Fingerprinting↗
PubMed2003

Microsatellite diversity among three endogamous Tamil populations suggests their origin from a separate Dravidian genetic pool.

The genetic profiles based on 15 autosomal microsatellite markers were analyzed among three socially distinct endogamous Dravidian populations: Tanjore Kallar, Vanniyar, and Pallar of Tamil Nadu, southern India, in order to understand their origin and the extent of genetic affinity and diversity among them. All loci were highly polymorphic and followed Hardy-Weinberg expectations except for loci D13S317 in Tanjore Kallars and D7S820 in Vanniyars. The SK2 criterion test showed no evidence of association among the 15 loci in the studied populations. The extent of gene differentiation among the three populations was low (G(ST) = 0.012), suggesting proximity between them. The phylogenetic dendrogram based on allele frequencies places them in a separate cluster, away from other compared Indo-European populations. The fit of the Harpending and Ward model of regression was found to be good and consistent with the extent of endogamy followed by the respective populations. These findings support a separate origin of the Dravidians and reveal an overall genetic unity among the studied Tamil populations belonging to different strata of the social hierarchy. The extent of diversity found among them probably resulted from the strict endogamous practices that they follow.

Alleles↗
PubMed2002

Genomic diversity at 15 fluorescent labeled short tandem repeat loci in few important populations of State of Uttar Pradesh, India.

Genomic diversity at 15 short tandem repeat loci is studied in four major endogamous populations of Uttar Pradesh (UP), India. The studied populations included Thakur, Khatri, Kurmi and Jat; all of whom belong to Hindi speaking linguistic group of UP State of India. All the STR loci of Powerplex 16 System have been found highly significant in showing genomic diversity among the addressed populations. Homozygosity test values for all the 15 loci in studied population range between 0.053 and 0.999, following Hardy-Weinberg equilibrium. Distribution of allele pattern at fluorescent labeled 13 tetranucleotide repeat loci and two pentanucleotide repeat loci of Powerplex 16 System portrays that these markers are highly polymorphic, and thus, suitable in human identity testing and human genetic studies.

Gene Frequency↗
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

Novel pattern forming process due to the coupling of convection and phase change.

We present a novel mechanism of pattern formation behind a flat interface during directional solidification of peritectic alloys. It is shown through computational modeling that irregular oscillatory thermosolutal convection can develop in the vertical Bridgman system, even with bottom seeding and bottom cooling. The coupling of the flow oscillation near the interface with solidification leads to ordered layered structures in the solidified crystal, which agree closely with earlier experimental results.

Journal Article↗
PubMed2002

Allele frequencies for STR loci of the Powerplex 16 multiplex system in five endogamous populations of India.

Allele frequencies for the 15 STR locus of PowerPlex 16 were analyzed in 95 healthy unrelated individuals belonging to five important population groups inhabiting different part of India. Fifteen loci studied are Penta E, D18S51, D21S11, THO1,D3S1358, FGA, TPOX, D8S1179, vWA, Amelogenin, Penta D, CSF1PO, D16S539, D7S820, D13S317 and D5S818. In addition of all tetra nucleotide loci, two penta nucleotide loci Penta D and Penta E of the studied system are also found highly polymorphic in all the five studied populations of India. These loci are found highly informative in solving paternity cases and other forensic testing in studied population.

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↗
PubMed2000

Autoantibody screening in subacute cerebellar ataxia.

In a retrospective study of 280 sera from patients presenting with cerebellar signs, seven of whom had proved positive for the typical paraneoplastic serum antibodies that were requested by the clinicians, raised concentrations of antibodies to voltage-gated calcium channels or to glutamic acid decarboxylase were detected in a further seven sera. Systematic screening for these and other antibodies in future cases should help in the diagnosis and management of the patients.

Autoantibodies↗
PubMed2000

Focal amyotrophy in neurofibromatosis 2.

Neurofibromatosis type 2 (NF2) is an autosomal dominant disorder characterised by bilateral vestibular schwannomas and other CNS tumours including meningiomas and spinal schwannomas. Occasionally, peripheral neuropathy occurs in these patients but this is the first report of focal amyotrophy. Clinical, electrophysiological, and imaging data from four NF2 patients seen at a specialist neurofibromatosis clinic over a 4 year period are described in whom symptomatic focal amyotrophy preceded the diagnosis of NF2. Two presented with wasting and weakness of a single muscle group, several years before NF2 was diagnosed. In one patient a mononeuritis multiplex was the presenting feature of NF2, and in one patient focal wasting and weakness developed after the diagnosis of NF2 was made. In none of the four cases could a focal peripheral nerve or root neurofibroma be identified despite extensive imaging with MRI, and the limitations of neuroimaging for identifying a structural cause in patients with NF2 with a focal peripheral nerve lesion is discussed. It is likely that NF2 may affect peripheral nerve structures in a manner distinct from a compressive schwannoma.

Adolescent↗
PubMed2000

Hepatic and renal oxidative stress in acute toxicity of N-nitrosodiethylamine in rats.

Nitrosoamines such as N-nitrosodiethylamine (NDEA) produce oxidative stress due to generation of reactive oxygen species and may alter antioxidant defence system in the tissues. NDEA was administered ip as a single dose to rats in LD50 or in lower amounts and the animals were sacrificed after 0-48 hr of treatment. The results showed that lipid peroxidation in liver increased, however no significant increase in kidney LPO was observed after NDEA administration. Superoxide dismutase (SOD) and glutathione reductase (GSH-R) activity increased in liver, however, catalase (CAT) activity in liver was inhibited in NDEA treated rats. Kidney showed an increase in SOD activity after an initial decrease along with increase in GSH-R activity in NDEA treated rats. However, kidney CAT activity was not significantly altered in NDEA intoxicated rats. Serum transaminases, serum alkaline phosphatase blood urea nitrogen, serum creatinine and scrum proteins were elevated in NDEA treated rats. The results indicate NDEA-induced oxidative stress and alteration in antioxidant enzymes in liver and kidney to neutralise oxidative stress.

Alkylating Agents↗
PubMed1995

Cadmium-induced lipid peroxidation and the status of the antioxidant system in rat tissues.

Cadmium may induce oxidative damage in different tissues by enhancing peroxidation of membrane lipids and altering the antioxidant system of the cells. The peroxidative damage to the cell membrane may cause injury to cellular components due to the interaction of metal ions with the cell organelles. The treatment with Cd (0.4 mg/kg body wt, ip) significantly increased lipid peroxidation (LPO) in heart within 3 h of the Cd injection, while the increase in kidney and liver followed 6 to 12 h after Cd intoxication. The antioxidant enzymes and other antioxidants provide protection to the cells against oxidative damage. The superoxide dismutase (SOD) activity increased in heart, kidney and liver within 24 h of Cd intoxication. The CAT activity increased significantly in heart 9 h after Cd injection; however, no significant change in CAT activity was observed in kidney and liver tissues. The GSH content and the activity of GR decreased in heart, kidney and liver 72 h after Cd administration, which has been suggested to be the cause for increased LPO in the tissues. The hexose monophosphate (HMP) shunt enzymes generate NADPH required for the activity of GR which may affect the GSH content in the tissues. The generalised decrease in glucose 6-phosphate dehydrogenase (G6PDH) and 6 phospho gluconate dehydrogenase (6PGDH) at 9 h followed by an increase in these enzymes in tissues 72 h after Cd intoxication suggest that the production of NADPH by the HMP shunt is required to reduce the oxidative damage. The results show that Cd induced LPO in the tissues and the condition was partially counteracted by the antioxidant system.

Animals↗
PubMed1995

Selective dendritic alterations in the cortex of Rett syndrome.

Rett syndrome, the commonest condition associated with severe mental retardation in girls, is diagnosed only by its clinical phenotype, because, to date, there is no consistent characteristic alteration in genetic, biochemical, neurotransmitter or morphologic marker. The clinical features at various ages suggest involvement of most parts of the nervous system, however, the brain in Rett syndrome is reduced in weight, without other obvious morphologic alterations. Because of the relative microcephaly, hypotheses regarding failure of development have been suggested. Supporting such hypotheses are the quantitative studies by Jellinger, Seitelberger and Kitt defining a decrease in the amount of melanin in the substantia nigra and by Bauman defining a global decrease in the size of the neurons. In this study the cerebral cortex has been examined using the rapid Golgi technique with the purpose of investigating dendrites of pyramidal neurons in six cortical regions of Rett girls from ages 2.9-35 years. Camera lucida drawings of apical and basal dendrites of two cortical layers and CA1 were prepared. These were submitted to the Sholl analysis. The Sholl analyses were tested for significance using the repeated measures analysis of covariance, with age as a covariate. The studies demonstrate that from our samples there is no evidence that the pyramidal neurons in Rett syndrome degenerate progressively with increasing age but that the basal dendrites of layers three and five pyramidal neurons in the motor and frontal cortex, the apical dendrites of layer five of the motor cortex, and the basal dendrites of layer four of the subiculum are significantly shorter than in non-Rett brains.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗