Showing papers by "University of Madras published in 2000"
TL;DR: In this paper, the average grain size and the root mean square strain were estimated from the x-ray diffraction line broadening, and the lattice parameter initially decreases slightly with milling and it increases with further milling.
Abstract: Nanostructured ZnFe2O4 ferrites with different grain sizes were prepared by high energy ball milling for various milling times. Both the average grain size and the root mean square strain were estimated from the x-ray diffraction line broadening. The lattice parameter initially decreases slightly with milling and it increases with further milling. The magnetization is found to increase as the grain size decreases and its large value is attributed to the cation inversion associated with grain size reduction. The Fe-57 Mossbauer spectra were recorded at 300 K and 77 K for the samples with grain sizes of 22 and 11 nm. There is no evidence for the presence of the Fe2+ charge state. At 77 K the Mossbauer spectra consist of a magnetically ordered component along with a doublet due to the superparamagnetic behaviour of small crystalline grains with the superparamagnetic component decreasing with grain size reduction. At 4.2 K the sample with 11 nm grain size displays a magnetically blocked state as revealed by the Mossbauer spectrum. The Mossbauer spectrum of this sample recorded at 10 K in an external magnetic field of 6 T applied parallel to the direction of gamma rays clearly shows ferrimagnetic ordering of the sample. Also, the sample exhibits spin canting with a large canting angle, maybe due to a spin-glass-like surface layer or grain boundary anisotropies in the material.
339 citations
01 Feb 2000-Comparative Biochemistry and Physiology Part C: Pharmacology, Toxicology and Endocrinology
TL;DR: Ecdysteroids are the molting hormones in Crustacea and they also subserve functions in the control of reproduction and embryogenesis, although recent evidence suggests a stimulatory role for yet another endocrine gland, the mandibular organ on Y-organ synthesis.
197 citations
TL;DR: The standard method seems to be the most efficient followed by the new method and the differential version of the standard method (in that order), as far as the CPU time for the computation of the Lyapunov spectra is concerned.
196 citations
TL;DR: Evidence is provided that DL-alpha-lipoic acid treatment can improve antioxidants during aging and minimize the age-associated disorders in which free radicals are the major cause.
Abstract: Oxidative metabolism produces free radicals that must be removed from the cellular environment for the cell to survive. The levels of nonenzymic antioxidants involved in the elimination of free radicals were investigated in an attempt to correlate any changes in the levels of enzymic antioxidants during aging with changes in free radical mediated cellular damage. Antioxidants were measured in liver and kidney of young and aged rats with respect to DL-α-lipoic acid supplemented rats. In both organs lipid peroxidation damage (a marker of free radical mediated damage) increased with age, and a significant decrease in antioxidant systems was observed. Moreover, DL-α-lipoic acid treated aged rats showed a decrease in the level of lipid peroxides and an increase in the antioxidant status. The results of this study provide evidence that DL-α-lipoic acid treatment can improve antioxidants during aging and minimize the age-associated disorders in which free radicals are the major cause.
112 citations
TL;DR: The present study indicates the feasibility of in situ formation of BCP ceramics using microwave irradiation and in vitro solubility study in phosphate buffer showed the resorbable nature of the BCP samples.
102 citations
TL;DR: This is the first occasion in Crustacea in which multiple Vns were demonstrated to be synthesized simultaneously in a single tissue.
Abstract: Four major yolk proteins, designated as vitellins (Vns) Macr-VnA, B, C, and D, were extracted from mature ovaries of Macrobrachium rosenbergii. These were purified to homogeneity by reversed-phase high performance liquid chromatography (HPLC) employing a unique separation system based on the hydrophobic properties of the Vn molecule. Using standard techniques of protein sequencing, more than 33 N-terminal and 57 internal amino acid residues were determined for each of the four Vns. The cDNA fragments encoding the four Vns were amplified by PCR using degenerate oligonucleotide primers derived from the N-terminal and internal amino acid sequences. These cDNA fragments were cloned, sequenced, and used as probes to examine the transcription of mRNAs encoding the four Vns. Significant accumulations of these mRNAs were observed in female hepatopancreas only, while mRNA expression was not detected in male hepatopancreas or any other female tissue including ovary, subepidermal adipose tissue, gill, and muscle. This is the first occasion in Crustacea in which multiple Vns were demonstrated to be synthesized simultaneously in a single tissue. J. Exp. Zool. 287:413–422, 2000. © 2000 Wiley-Liss, Inc.
83 citations
TL;DR: A large number of dermatologic manifestations, which may at times constitute the presenting symptoms, are well delineated in the Western literature, but there is a paucity of information from the southern part of the Indian subcontinent.
Abstract: Background Human immunodeficiency virus (HIV) may be associated with a large number of dermatologic manifestations, which may at times constitute the presenting symptoms. These skin lesions are well delineated in the Western literature, but there is a paucity of information from the southern part of the Indian subcontinent. Objective We evaluated 833 persons with HIV to determine the types of dermatologic lesions present. Results The various lesions observed were oral candidiasis (45.0%), multidermatomal herpes zoster (11.2%), dermatophytosis of the skin (8.0%), herpes genitalis (7.7%), papular pruritic dermatitis (7.7%), staphylococcal infection of the skin (2.9%), oral hairy leukoplakia (2.3%), molluscum contagiosum (1.3%), genital warts (1.2%), and scabies (0.5%). Alopecia, intractable itching, dry skin, Addisonian pigmentation, and Kaposi's sarcoma were also noted. A correlation between the dermatologic manifestations and CD4 cell counts was found. Conclusion Although the pattern of cutaneous lesions was comparable with that from the West, there is a strikingly lower incidence of Kaposi's sarcoma.
82 citations
TL;DR: Oral treatment with the ethanol extract of Hemidesmus indicus roots (100 mg/kg, for 15 days) significantly prevented rifampicin and isoniazid-induced hepatotoxicity in rats.
79 citations
TL;DR: Lupeol, when supplemented at a dosage of 40 mg kg−1 body weight concurrent with cadmium administration, showed an improvement in the antioxidant status and the level of lipid peroxides showed a significant decrease, which shows the nephroprotective action of the drug.
Abstract: This study pertains to the role of lupeol, a pentacyclic triterpene, against the toxic manifestations of chronic cadmium exposure. Cadmium is a potent nephrotoxin on prolonged exposure. Cadmium (as cadmium chloride) at a dose of 1 mg kg−1 body weight was administered subcutaneously for 15 days to rats. This led to an increase in the level of lipid peroxides and a decrease in the level of antioxidants in the kidney. Lupeol, when supplemented at a dosage of 40 mg kg−1 body weight concurrent with cadmium administration, showed an improvement in the antioxidant status. The level of lipid peroxides also showed a significant decrease, which shows the nephroprotective action of the drug Copyright © 2000 John Wiley & Sons, Ltd.
75 citations
TL;DR: In this article, the metal ion distribution in Mn-Zn ferrite particles prepared by co-precipitation and ceramic methods using extended X-ray absorption fine structure (EXAFS) technique was qualitatively analyzed.
73 citations
TL;DR: In this article, the soft magnetic properties of Fe73.5Cu1Nb3Si13.5B9 alloys were studied using various experimental techniques including Mossbauer spectroscopy.
TL;DR: Genotoxicity evaluation of heat shock was carried out in Carassius auratus and results indicate that heat shock is a genotoxicant.
Abstract: Genotoxicity evaluation of heat shock was carried out in Carassius auratus. The genotoxicity end points studied were nuclear anomalies (micronucleus assay), chromosomal aberrations, DNA damage (comet assay) and cell proliferation. The heat shock temperatures used were 34°C, 36°C and 38°C. The results demonstrated that heat shock causes the induction of micronucleus at all the three temperature studied. Heat shock also inhibited cell proliferation at 38°C and caused aberrations in the metaphase chromosomes at 34°C and 36°C. Comet assay demonstrated single strand DNA damage at all the three temperatures. The results obtained indicate that heat shock is a genotoxicant.
TL;DR: A toxicological study was carried out in rats with a Siddha preparation, milk extracts of Semecarpus anacardium nuts and Histopathological examination of vital organs showed normal architecture suggesting no morphological disturbances.
TL;DR: Morphological observation by phase contrast microscopy revealed that both crocetin and quercetin caused intense damage only on the malignant (RD) cells, whereas mild toxic effect was seen with cisplatin also on normal (Vero) cells.
TL;DR: Both lupeol and betulin were comparable in their ability to restore the thiol status and the antioxidant enzymes like superoxide dismutase, catalase and glutathione peroxidase, and may involve the inhibition of calcium oxalate crystal aggregation and enhancement of the body defence systems.
TL;DR: White spot baculovirus (WSBV) is considered to be the main causative agent responsible for mass mortalities of juveniles and sub-adults in the cultured Indian penaeid shrimp, P. monodon and P. indicus.
Journal Article•
TL;DR: In alternative medicine, medicinal plant preparations have found widespread use particularly in the case of diseases not amenable to treatment by modern methods, and understanding of the mechanism of the pharmacological action of S. anacardium nut can be greatly aided by the isolation of its active principle from the nut and determination of the structure-function relationship.
Abstract: In alternative medicine, medicinal plant preparations have found widespread use particularly in the case of diseases not amenable to treatment by modern methods. Chemical and phytochemical analyses of Semecarpus anacardium nut reveal the presence of biflavonoids, phenolic compounds, bhilawanols, minerals, vitamins and amino acids. A variety of nut extract preparations from this source are effective against many diseases, viz. arthritis, tumours, infections etc. and non-toxic even at high dose of 2000 mg/kg. However understanding of the mechanism of the pharmacological action of S. anacardium nut can be greatly aided by the isolation of its active principle from the nut and determination of the structure-function relationship. Also, the potent curative effect of S. anacardium nut extract against human ailments need to be verified by controlled clinical studies.
TL;DR: In this article, the authors studied the reaction of diperiodatoargentate (III) ion with the substrate and showed that the reaction rate shows an inverse dependence on [IO] and [OH−] in the low concentration range (≤1 × 10-3 mol dm−3).
Abstract: The oxidation of ethylenediamine by diperiodatoargentate (III) ion has been studied by stopped-flow spectrophotometry. Kinetics of this reaction involves two steps. The first step is the complexation of silver (III) with the substrate and is over in about 10 ms. This is followed by a redox reaction in the second step that occurs intramolecularly from the substrate to the silver (III) center. The rate of reduction of silver (III) species by ethylenediamine, ethanolamine, and 1,2-ethanediol were observed to be 1.2 × 104, 1.1 × 102, and 0.14 dm3 mol−1 s−1, respectively, at 20°C. The reaction rate shows an inverse dependence on [IO] and [OH−] in the low concentration range (≤1 × 10-3 mol dm−3). At higher [OH−] (>1 × 10−3 mol dm−3) the rate of reaction starts increasing and attains a limiting value at very high [OH−]. The rate of deamination of ethylenediamine is enhanced by its complexation with silver (III). The involvement of [AgIII(H2IO6) (H2O)2] and [AgIII(H2IO6) (OH)2]2− are suggested as the reactive silver (III) species kinetically in mild basic and basic conditions, respectively. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 286–293, 2000
TL;DR: In this paper, a modified carbon paste electrode was prepared with an aqueous insoluble redox mediator, ruthenium(III) diphenyldithiocarbamate.
TL;DR: Six popular Web OPAC interfaces in use in UK academic libraries have been examined with an overview of the functions offered via those interfaces and a checklist has been developed as an indicator of the important features and functions offered.
Abstract: Web‐based online public access catalogues (OPACs) began to appear in the late 1990s and many libraries are currently considering implementation. As catalogues, they demonstrate advances on traditional OPACs, especially in terms of remote access by users and their potential to integrate many document types and sources via a single interface. This paper considers some of the features and functions of Web OPAC interfaces. As yet, very little evaluation of systems and users has taken place and until more such literature appears, a general approach to products available is considered to be of value. Six popular Web OPAC interfaces in use in UK academic libraries (Talis, INNOPAC, WebCat, Voyager, GeoWeb and ALEPH) have been examined with an overview of the functions offered via those interfaces. A checklist has been developed as an indicator of the important features and functions offered.
TL;DR: The effect of ethanolic extract of Ocimum sanctum was studied on the noise stress induced changes in albino rats, indicating the stress alleviating effect of O. sanctum.
TL;DR: Results suggest that biochemical lesions which are considered to be part of the normal ageing process are neutralized by dl-alpha-lipoic acid.
TL;DR: A direct stimulatory effects of T3 is indicated on basal production of testosterone and oestradiol by Leydig cells and its modulatory effect on LH mediated steroidogenic activity varies depending upon the intensity of LH stimuli.
Abstract: The effect of T3 on basal and LH mediated synthesis and secretion of testosterone and oestradiol by puberal rat Leydig cells was studied in vitro. Percoll gradient purified Leydig cells (1 x 10(3)) were cultured for 48 hours at 34 degrees C in a medium containing a range of 5-400 ng/mL concentration of T3 or ovine LH after 24 hours initial culture at 37 degrees C. T3 increased testosterone and oestradiol secretions in a dose dependent manner which reached the saturation point with 50 ng dose. While the minimum effective dose of T3 (25 ng) potentiated the stimulatory effect of the minimum effective dose of LH (25 ng) on testosterone secretion, it suppressed the effect of the saturation dose of LH (100 ng). Fifty ng T3 quelled the stimulatory effect of either dose of LH. Both doses of T3 increased oestradiol secretion, irrespective of the dose of LH. Addition of androstenedione (500 ng/mL) to the culture medium enhanced 25 ng T3 induced testosterone and oestradiol secretions. While androstenedione potentiated the stimulatory effect of T3 (25 ng) on LH (25 ng) induced testosterone and oestradiol secretions, it reversed the inhibitory effect of 50 ng T3 on LH mediated testosterone secretion which was accompanied by a decrease in oestradiol secretion. Puromycin (35 microg/mL) suppressed the stimulatory effect of T3 on basal and LH mediated testosterone and oestradiol production. Taken together, the present results indicate a direct stimulatory effects of T3 on basal production of testosterone and oestradiol by Leydig cells and its modulatory effect on LH mediated steroidogenic activity varies depending upon the intensity of LH stimuli.
TL;DR: Cyanide reduced the memory along with reduction in the levels of dopamine and 5-hydroxytryptamine in the hippocampus in male Wistar strain albino rats, which exaggerated these effects of malnutrition in the animals.
TL;DR: The modulatory effect of lipoate in decreasing age-associated alterations observed in this study proves its role as a potent antioxidant in the brain of aged rats.
TL;DR: In vitro solubility study in phosphate buffer at physiological conditions shows the resorbable nature of these materials and enhanced TCP formation with reduced impurity phases was observed with TiO2-Ag2O addition.
TL;DR: Data suggests that NO has a GABA-T-inhibiting role in the brain, and that NO-decreasing action of l -NAME coincided with a reduction in the concentration of GABA and an enhancement of GABA- T activity.
TL;DR: In this paper, a series of novel heterocyclic derivatives containing the spiro bicyclo[2.2.1]heptane system is the outcome of such reactions.
TL;DR: Chronic cassava ingestion up to a year does not lead to either diabetes or chronic pancreatitis in the rat model, and transient changes in serum insulin and lipase levels are found, but the significance of these findings are not clear.
Abstract: Cassava (tapioca, manihot) is consumed as a staple food in some developing countries. The intake of cassava has been linked to several diseases including fibrocalculous pancreatic diabetes (tropical calcific pancreatitis). There are few long-term studies on the effect of cassava ingestion on the pancreas in animal models. This article reports on the long-term (up to 1 yr) effects of cassava in the rat model. We found that cassava did not produce diabetes in the rat even after a year of cassava feeding. There were transient changes in serum insulin and lipase levels, but the significance of these findings are not clear. There was no histopathological evidence of either acute or chronic pancreatitis, but there were changes of toxic hepatitis in the liver. In conclusion, chronic cassava ingestion up to a year does not lead to either diabetes or chronic pancreatitis in the rat model.
TL;DR: Results confirm that the rice and millet-infecting M. grisea populations in India are distinct and show that the blast fungus from the two hosts did not cross-infect, nor did the two forms cross in the laboratory.