Showing papers by "University of Madras published in 2001"

Usher Syndrome 1D and Nonsyndromic Autosomal Recessive Deafness DFNB12 Are Caused by Allelic Mutations of the Novel Cadherin-Like Gene CDH23

Abstract: Genes causing nonsyndromic autosomal recessive deafness (DFNB12) and deafness associated with retinitis pigmentosa and vestibular dysfunction (USH1D) were previously mapped to overlapping regions of chromosome 10q21-q22. Seven highly consanguineous families segregating nonsyndromic autosomal recessive deafness were analyzed to refine the DFNB12 locus. In a single family, a critical region was defined between D10S1694 and D10S1737, ∼0.55 cM apart. Eighteen candidate genes in the region were sequenced. Mutations in a novel cadherin-like gene, CDH23, were found both in families with DFNB12 and in families with USH1D. Six missense mutations were found in five families with DFNB12, and two nonsense and two frameshift mutations were found in four families with USH1D. A northern blot analysis of CDH23 showed a 9.5-kb transcript expressed primarily in the retina. CDH23 is also expressed in the cochlea, as is demonstrated by polymerase chain reaction amplification from cochlear cDNA.

Mixed spinel structure in nanocrystalline NiFe 2 O 4

Abstract: Nanocrystalline ${\mathrm{NiFe}}_{2}{\mathrm{O}}_{4}$ spinel has been synthesized with various grain sizes by high-energy ball milling. From the high-field magnetization studies and extended x-ray-absorption fine-structure, and M\"ossbauer measurements in an external magnetic field of 5 T applied parallel to the direction of gamma rays, we could observe that ${\mathrm{Ni}}^{2+}$ ions occupy tetrahedral sites on grain-size reduction due to milling. The ${\mathrm{Fe}}^{3+}$ spins have a canted structure and the canting angle increases with grain-size reduction. It is possible that the core ${\mathrm{Fe}}^{3+}$ spins are also canted because of the magnetocrystalline anisotropy introduced by the occupancy of the ${\mathrm{Ni}}^{2+}$ ions in the tetrahedral sites.

Genetic Evidence on the Origins of Indian Caste Populations

Abstract: The origins and affinities of the ∼1 billion people living on the subcontinent of India have long been contested. This is owing, in part, to the many different waves of immigrants that have influenced the genetic structure of India. In the most recent of these waves, Indo-European-speaking people from West Eurasia entered India from the Northwest and diffused throughout the subcontinent. They purportedly admixed with or displaced indigenous Dravidic-speaking populations. Subsequently they may have established the Hindu caste system and placed themselves primarily in castes of higher rank. To explore the impact of West Eurasians on contemporary Indian caste populations, we compared mtDNA (400 bp of hypervariable region 1 and 14 restriction site polymorphisms) and Y-chromosome (20 biallelic polymorphisms and 5 short tandem repeats) variation in ∼265 males from eight castes of different rank to ∼750 Africans, Asians, Europeans, and other Indians. For maternally inherited mtDNA, each caste is most similar to Asians. However, 20%–30% of Indian mtDNA haplotypes belong to West Eurasian haplogroups, and the frequency of these haplotypes is proportional to caste rank, the highest frequency of West Eurasian haplotypes being found in the upper castes. In contrast, for paternally inherited Y-chromosome variation each caste is more similar to Europeans than to Asians. Moreover, the affinity to Europeans is proportionate to caste rank, the upper castes being most similar to Europeans, particularly East Europeans. These findings are consistent with greater West Eurasian male admixture with castes of higher rank. Nevertheless, the mitochondrial genome and the Y chromosome each represents only a single haploid locus and is more susceptible to large stochastic variation, bottlenecks, and selective sweeps. Thus, to increase the power of our analysis, we assayed 40 independent, biparentally inherited autosomal loci (1 LINE-1 and 39 Alu elements) in all of the caste and continental populations (∼600 individuals). Analysis of these data demonstrated that the upper castes have a higher affinity to Europeans than to Asians, and the upper castes are significantly more similar to Europeans than are the lower castes. Collectively, all five datasets show a trend toward upper castes being more similar to Europeans, whereas lower castes are more similar to Asians. We conclude that Indian castes are most likely to be of proto-Asian origin with West Eurasian admixture resulting in rank-related and sex-specific differences in the genetic affinities of castes to Asians and Europeans.

Mutations in the novel protocadherin PCDH15 cause Usher syndrome type 1F

Abstract: We have determined the molecular basis for Usher syndrome type 1F (USH1F) in two families segregating for this type of syndromic deafness By fluorescence in situ hybridization, we placed the human homolog of the mouse protocadherin Pcdh15 in the linkage interval defined by the USH1F locus We determined the genomic structure of this novel protocadherin, and found a single-base deletion in exon 10 in one USH1F family and a nonsense mutation in exon 2 in the second Consistent with the phenotypes observed in these families, we demonstrated expression of PCDH15 in the retina and cochlea by RT-PCR and immunohistochemistry This report shows that protocadherins are essential for maintenance of normal retinal and cochlear function

Protective role of Bacopa monniera on morphine induced hepatotoxicity in rats.

Abstract: The protective effect of Bacopa monniera on morphine induced liver antioxidant levels was studied in rats. Oral administration of alcohol extracts of Bacopa monniera induced a significant hepatoprotective effect. In the morphine treated group, a significant increase of lipid peroxidation and a significant decrease in liver antioxidant enzyme levels were observed. Simultaneous administration of morphine and Bacopa extract prevented these alterations. The results of this study showed that Bacopa monniera alcohol extract exerted a hepatoprotective effect against morphine induced liver toxicity.

Inhibition of genotoxicity by saffron (crocus sativus l.) in mice

Abstract: Experiments were carried out to ascertain whether or not saffron (dried stigmas of Crocus sativus L.), a commonly used agent for flavoring and coloring food can exert modulatory effects on the in v...

Occurrence of vertebrate steroids, estradiol 17β and progesterone in the reproducing females of the mud crab Scylla serrata

Abstract: In crustaceans, vitellogenesis is known to be controlled by eyestalk neuropeptides, biogenic amines, ecdysteroids and a juvenile hormone-like compound, methyl farnesoate. In recent years, the occurrence of vertebrate steroid hormones, estradiol 17beta (E2) and progesterone (PG) has also been reported in a few decapods, although their precise role in female reproduction is yet to be determined. The levels of E2 and PG in the ovary, hepatopancreas and the hemolymph of the red mud crab, Scylla serrata were analyzed in different vitellogenic stages in order to establish a correlation between hormone profile and stages of vitellogenesis. It was observed that the levels of both the steroids increased steeply in the tissues at the onset of vitellogenesis (vitellogenic stage I). Maximum levels of estradiol were present in the hepatopancreas whereas the highest concentration of progesterone was seen in the ovary, suggesting dichotomous roles for these hormones in vitellogenesis. Furthermore, levels of these hormones were estimated in different embryonic stages of the eggs of the sand crab Emerita asiatica and mud crab S. serrata. Their levels fluctuated, following a definite pattern in the different stages, suggesting a possible functional role as morphogenetic hormones. This study, in addition, also reports the presence of E2 and PG on lipovitellin purified from ovary and eggs as well as vitellogenin purified from the hemolymph implicating a role for these lipoproteins as steroid carriers.

The influence of Fe3+ ions at tetrahedral sites on the magnetic properties of nanocrystalline ZnFe2O4

Abstract: A systematic study on the variation of Mossbauer hyperfine parameters with grain size in nanocrystalline zinc ferrite is lacking. In the present study, nanocrystalline ZnFe2O4 ferrites with different grain sizes were prepared by ball-milling technique and characterised by X-ray, EDAX, magnetisation and Mossbauer studies. The grain size decreases with increasing milling time and lattice parameter is found to be slightly higher than the bulk value. Magnetisation at room temperature (RT) and at 77 K could not be saturated with a magnetic field of 7 kOe and the observed magnetisation at these temperatures can be explained on the basis of deviation of cation distribution from normal spinel structure. The Mossbauer spectra were recorded at different temperatures between RT and 16 K. The values of quadrupole splitting at RT are higher for the milled samples indicating the disordering of ZnFe2O4 on milling. The strength of the magnetic hyperfine interactions increases with grain size reduction and this can be explained on the basis of the distribution of Fe3+ ions at both tetrahedral and octahedral sites.

Studies on defluoridation of water by coal-based sorbents

Abstract: Drinking water containing fluoride above a level of 1 mg/dm 3 is considered to be unsafe for human consumption. Higher intake of fluoride can cause potential health hazards. The conventional processes of fluoride removal from water are ion exchange, reverse osmosis and electro-dialysis. However, the utility of these processes has been limited due to their expensive operation and subsequent disposal problem of the waste brine generated. Defluoridation of water samples by coal-based sorbents was studied at different adsorbent dosages. First-order adsorption rate constants using the Lagergren equation, the Freundlich adsorption isotherm, the Langmuir adsorption isotherm, film diffusion and pore diffusion coefficients have been evaluated for each system. The effect of pH on fluoride removal and the mechanism has also been discussed.

Effect of selenium on N-nitrosodiethylamine-induced multistage hepatocarcinogenesis with reference to lipid peroxidation and enzymic antioxidants.

Abstract: We have studied the relationship between antioxidant and anticancer properties of selenium (Se) in multistage hepatocarcinogenesis induced by N-nitrosodiethylamine (DEN). In this study we have observed an increased level of lipid peroxide (LPO) products and decreased antioxidant enzyme activities (superoxide dismutase and catalase) in hepatoma and surrounding liver tissues of cancer-bearing animals. Selenium (Se) was supplemented either before initiation or during initiation and selection/promotion phases of hepatocarcinogenesis and was found to be effective in altering hepatic lipid peroxidation and antioxidant enzyme activities to a statistically significant level measured either in the hepatoma or in the surrounding liver tissues. These alterations inclined towards normal in a time-dependent manner on selenium supplementation. Furthermore, increased levels of lipid peroxidation and decreased levels of antioxidants (superoxide dismutase and catalase) were also observed in distant organs of cancer-bearing rats other than the tumour-bearing site. These alterations are brought back to normal levels upon Se treatment. Our results confirm the fact that Se is particularly protective in limiting the action of DEN by its antioxidant property. Copyright © 2001 John Wiley & Sons, Ltd.

Inclusion of Resorcinol-Based Acridinedione Dyes in Cyclodextrins: Fluorescence Enhancement†

Abstract: The inclusion of acridinedione dyes (ADR) with β-cyclodextrins (β-CD) in the presence of 0.6% methanol is studied using absorption and fluorescence techniques. The association constant was determined by using the Benesi−Hildebrand plot and also by nonlinear regression analysis. A stoichiometry of 1:1 was found for β-CD/ADR (3−5). The nonobservation of the changes in the absorption or the fluorescence in the case of dyes 1 and 2 clearly indicates that the phenyl substituent at the −N atom in the ADR (3−5) is included in the β-CD cavity. Thermodynamic parameters ΔH and ΔS values obtained from the temperature-dependent binding constants of the β-CD/ADR (3−5) system are reported. In the presence of β-CD, the fluorescence of ADR (4) dye shows single exponential decay, consistent with the completion of complex formation, and ADR (3, 5) showed a double exponential decay, consistent with the equilibrium between free and complexed forms. The binding constants and thermodynamic factors are systematically resolved t...

Chemopreventive efficacy of selenium against N-nitrosodiethylamine-induced hepatoma in albino rats.

Abstract: The chemopreventive/chemotherapeutic effect of sodium selenite on tricarboxylic acid cycle key enzymes was investigated against hepatoma induced by environmental carcinogen N-nitrosodiethylamine. Decreased activities of TCA cycle key enzymes such as isocitrate dehydrogenase (ICDH), succinate dehydrogenase (SDH), malate dehydrogenase (MDH) and alpha-ketoglutarate dehydrogenase (alpha-KGDH) in hepatoma and surrounding tissues of hepatoma-bearing rats were observed. Upon selenium supplementation the above biochemical changes were reverted in a dose- and duration-dependent manner. This study further confirms the chemopreventive/chemotherapeutic effect of sodium selenite which is found to be more effective in the initiation phase of carcinogenesis.

Small-angle neutron scattering study of sodium cholate and sodium deoxycholate interacting micelles in aqueous medium

Abstract: Small angle neutron scattering (SANS) measurements of D2O solutions (0.1 M) of sodium cholate (NaC) and sodium deoxycholate (NaDC) were carried out atT= 298 K. Under compositions very much above the critical micelle concentration (CMC), the bile salt micelle size growths were monitored by adopting Hayter-Penfold type analysis of the scattering data. NaC and NaDC solutions show presence of correlation peaks atQ = 0.12 and 0.1 a-1 respectively. Monodisperse ellipsoids of the micelles produce best fits. For NaC and NaDC systems, aggregation number (9.0, 16.0), fraction of the free counterions per micelle (0.79, 0.62), semi-minor (8.0 a) and semi-major axes (18.4, 31.7 a) values for the micelles were deduced. Extent of micellar growth was studied using ESR correlation time measurements on a suitable probe incorporating NaC and NaDC micelles. The growth parameter (axial ratio) values were found to be 2.3 and 4.0 for NaC and NaDC systems respectively. The values agree with those of SANS.

Protective role of L-carnitine on liver and heart lipid peroxidation in atherosclerotic rats.

Abstract: Lipid peroxides are considered to be the initiation factor for atherosclerosis. Present study depicts that L-carnitine treatment (300 mg/kg body weight/day) for 7 and 14 days caused significant reduction in the tissue lipid peroxidations. It also shows marked improvement in the antioxidant status. By this way carnitine maintain the normal function of the cells.

Excited state reactions of acridinedione dyes with onium salts: mechanistic details☆

Abstract: Diaryliodonium and triarylsulphonium salts are thermally stable UV photoinitiators for cationic polymerization. Diaryliodonium salts (DPI-1–7) and triarylsulphonium (type-I, type-II and type-III) salts with different substituent have been prepared. Excited state reactions of these onium salts with decahydroacridinedione dyes (ADD-1–6) have been studied. ADD acts as an efficient sensitizer for the decomposition of these onium salts. Photosensitization occurs through electron transfer, which is confirmed by the observation of enol radical cation of ADD and diarylsulphinium radical cation in the laser flash photolysis. The mechanism of photosensitization and the mechanism of photoacid release have been discussed. Both singlet and triplet state of the ADD are involved in the photosensitization of diaryliodonium salts, whereas singlet state of ADD is alone involved in the photosensitization of triarylsulphonium salts. The quantum yield of photoacid generated in direct and the sensitized process is determined and this allows to gauge the practical efficiency of onium salts/ADD combinations as the photoinitiator for the cationic polymerization applications.