Showing papers by "North Eastern Hill University published in 2002"

Genotoxic effects of malathion: an organophosphorus insecticide, using three mammalian bioassays in vivo

Abstract: The genotoxic effects of malathion was evaluated using chromosome aberration, sister chromatid exchange (SCE) and sperm abnormality assays in mice. All the three acute doses (2.5, 5 and 10 mg/kg) of malathion tested in the present study, induced significant dose-dependent increase in the frequency of chromosome aberrations and sperm abnormalities, but did not affect the total sperm count. The highest acute dose induced a >12-fold increase in the frequency of chromosome aberrations, two-fold increase in the frequency of SCEs and four-fold increase in the frequency of sperms with abnormal head morphology following intraperitoneal (i.p.) exposure. Further, a significant increase in the frequency of SCEs was observed, but the increase was not dose-dependent. At higher doses, malathion induced a moderate delay in cell cycle as evident from the increase in average generation time (AGT). The present findings suggest that technical grade malathion is a potent genotoxic agent and may be regarded as a potential germ cell mutagen also.

Body mass index and morbidity in adult males of the War Khasi in Northeast India

Abstract: Objective: Data on the relationship between obesity, or high body mass index (BMI), and morbidity in adult individuals are frequently reported, but little is known about the relationship between morbidity and low BMI especially in developing countries. The present study was therefore an attempt to evaluate the relationship between BMI and morbidity in adult individuals. Design: The analyses were derived from the data based on self-reported morbidity and anthropometric measurements taken on adult males. The results were presented according to age and income groups for individuals of reporting and non-reporting illness. Subjects: The total sample size was 575 adult males (18–59 y) of the War Khasi population. Setting: Rural area of the state of Meghalaya in Northeast India. Results: The prevalence of chronic energy deficiency (CED) was found to be 35%, although the mean BMI (20.06±2.65 kg/m2) in individuals of non-reporting illness was higher than in those reported for many populations of Northeast India. The relationship between BMI and reported illness was not significant, although the morbidity curve tended to be U-shaped, and the prevalence of reported illness (32%) was highest in the individuals with BMI below 17.0 kg/m2. Moreover, the suggested cut-off 18.5 of BMI for screening the prevalence of CED did not correspond with the rise in morbidity, but both BMI and morbidity were significantly associated with age and income of the household. Conclusion: In view of the present analysis and other related literature, BMI is likely to be a better indicator of standards of living than a predictor of illness as the latter may also predispose individuals to the former. Thus, morbidity and low BMI may be considered parts of ill health, which are influenced by a number of biological and environmental factors especially age, economic conditions, undernutrition, safe water sanitation, community pathogens, prevention and control measures of locally endemic diseases and infections.

Colonization of roots of rice (Oryza sativa) by symbiotic Nostoc strains

Abstract: Summary • The lack of nitrogen in agriculture, and negative environmental effects of fertilizers, have stimulated interest in creating artificial associations between N2-fixing cyanobacteria and rice (Oryza sativa). • For the first time, numerous (57) Nostoc isolates from natural symbioses were screened for their ability to associate with rice. Successful colonizers were tested for N2-fixation by acetylene reduction, and for their ability to adsorb to roots by chlorophyll a measurements. Paranodules were induced by 2,4-dichlorophenoxyacetic acid. And genetic fingerprints of the cyanobacteria were obtained for identification. Ultrastructural investigations were made by light and scanning electron microscopy. • Twenty-one symbiotic Nostoc isolates associated with rice roots, colonizing surfaces and intercellular spaces. Adsorption was high and appeared biphasic. The rates of N2 fixation by associated cyanobacteria were higher compared with those in free-living cyanobacteria. Paranodules were formed and colonized, but root growth was adversely affected. • Under laboratory conditions, artificial associations were created between one-third of the screened symbiotic cyanobacteria and rice. The agricultural potential for the association appears high since the cyanobacteria adsorb tightly and fix more N2 than when free-living.

Mutagenic effects of carbosulfan, a carbamate pesticide

Abstract: The genotoxic effects of carbosulfan were evaluated using chromosome aberration (CA), bone marrow micronucleus (MN) and sperm abnormality assays in mice. All the three acute doses (1.25, 2.5 and 5 mg/kg) of carbosulfan induced significant dose-dependent increase in the frequency of CA ( P P P 7-fold increase in the frequency of CA, >3.5-fold increase in the frequency of micronucleated PCEs and >4.6-fold increase in the frequency of sperms with abnormal head morphology following intraperitoneal exposure as compared to the untreated controls. The present findings suggest that carbosulfan is a potent genotoxic agent and may be regarded as a potential germ cell mutagen also.

Role of amino acid metabolism in an air-breathing catfish, Clarias batrachus in response to exposure to a high concentration of exogenous ammonia.

Abstract: The air-breathing ureogenic walking catfish (Clarias batrachus) faces various environmental constraints throughout the year leading to the problem of accumulation of toxic ammonia. In the present study, the possible role of conversion of accumulated ammonia to various non-essential free amino acids (FAAs) was tested in this fish under hyper-ammonia stress caused by exposing the fish at 25 mM NH4Cl for 7 days. Significant accumulation of ammonia of approximately two- to threefold was observed in different tissues (except in the brain), which was accompanied with the significant accumulation of non-essential FAAs in the NH4Cl-exposed fish. There was approximately two- to threefold increase of non-essential FAAs in different tissues and in the plasma of the NH4Cl-exposed fish compared to the control fish after 7 days of exposure, which was mainly attributable to the increase of Asp, Ala, Gly, Glu, Gln and taurine (Tau) concentrations in general, with certain tissue-specific variations. This was also accompanied with significant increase of activity of certain amino acid metabolism-related enzymes such as the glutamine synthetase (approx. two- to threefold), glutamate dehydrogenase (ammonia utilizing direction) (approx. twofold), aspartate and alanine aminotransaminases (approx. twofold) mainly in the liver, kidney and muscle of the NH4Cl-exposed fish. Thus, it appears that the walking catfish has the capacity of active conversion of accumulated ammonia to non-essential FAAs under condition of high concentrations of external ammonia. However, the increase of urea excretion rate due to active conversion of ammonia to urea via the induced urea cycle appears to be quantitatively much more important pathway than the increase of tissue levels of FAAs in dealing with a severe ammonia load.

Hysteresis in the random-field Ising model and bootstrap percolation.

Abstract: We study hysteresis in the random-field Ising model with an asymmetric distribution of quenched fields, in the limit of low disorder in two and three dimensions. We relate the spin flip process to bootstrap percolation, and show that the characteristic length for self-averaging ${L}^{\ensuremath{\star}}$ increases as $\mathrm{exp}[\mathrm{exp}(J/\ensuremath{\Delta})]$ in 2D, and as $\mathrm{exp}{\mathrm{exp}[\mathrm{exp}(J/\ensuremath{\Delta})]}$ in 3D, for disorder strength $\ensuremath{\Delta}$ much less than the exchange coupling $J$. For system size $1\ensuremath{\ll}Ll{L}^{\ensuremath{\star}}$, the coercive field ${h}_{\mathrm{coer}}$ varies as $2J\ensuremath{-}\ensuremath{\Delta}\mathrm{ln}\mathrm{ln}L$ for the square lattice, and as $2J\ensuremath{-}\ensuremath{\Delta}\mathrm{ln}\mathrm{ln}\mathrm{ln}L$ on the cubic lattice. Its limiting value is 0 for $L\ensuremath{\rightarrow}\ensuremath{\infty}$ for both square and cubic lattices. For lattices with coordination number 3, the limiting magnetization shows no jump, and ${h}_{\mathrm{coer}}$ tends to $J$.

Hydrophobicity-induced deprotonation of dye in dye–submicellar surfactant systems

Abstract: Interaction of aqueous sulfonephthalein dyes, viz., phenol red, cresol red and cresol purple with alkyltrimethylammonium and alkylpyridinium halide surfactants in submicellar concentration ranges of the surfactants has been studied by UV–VIS spectroscopy. The spectral changes of the dyes observed on addition of the surfactants at concentrations far below critical micelle concentration (c.m.c.) indicate the formation of doubly deprotonated dye anions, which otherwise are formed only at much higher pH in the absence of the surfactant. The equilibrium constants for the interactions were determined. The deprotonation has been found to increase considerably with increase in hydrophobicity of the surfactant. It has been suggested that combined electrostatic–hydrophobic interaction increases acidity of the sulfonephthalein dyes in their closely packed dye–surfactant ion-pairs, formed at concentrations of surfactant far below c.m.c., causing deprotonation of the dye.

Effect of alkalinity (pH 10) on ureogenesis in the air-breathing walking catfish, Clarias batrachus.

Abstract: Exposure of fish to alkaline conditions inhibits the rate of ammonia excretion, leading to ammonia accumulation and toxicity. The purpose of this study was to determine the role of ureogenesis via the urea cycle, to avoid the accumulation of ammonia to a toxic level during chronic exposure to alkaline conditions, for the air-breathing walking catfish, Clarias batrachus, where a full complement of urea cycle enzyme activity has been documented. The walking catfish can survive in water with a pH up to 10. At a pH of 10 the ammonia excretion rate by the walking catfish decreased by approximately 75% within 6 h. Although there was a gradual improvement of ammonia excretion rate by the alkaline-exposed fish, the rate remained 50% lower, even after 7 days. This decrease of ammonia excretion was accompanied by a significant accumulation of ammonia in plasma and body tissues (except in the brain). Urea-N excretion for alkaline-exposed fish increased 2.5-fold within the first day, which was maintained until day 3 and was then followed by a slight decrease to maintain a 2-fold increase in the urea-N excretion rate, even after 7 days. There was also a higher accumulation of urea in plasma and other body tissues (liver, kidney, muscle and brain). The activity of glutamine synthetase and three enzymes operating in the urea cycle (carbamyl phosphate synthetase, argininosuccinate synthetase, argininosuccinate lyase) increased significantly in hepatic and extra-hepatic tissue, such as the kidney and muscle in C. batrachus, during exposure to alkaline water. A significant increase in plasma lactate concentration noticed during alkaline exposure possibly helped in the maintenance of the acid–base balance. It is apparent that the stimulation of ureogenesis via the induced urea cycle is one of the major physiological strategies adopted by the walking catfish (C. batrachus) during chronic exposure to alkaline water, to avoid the in vivo accumulation of ammonia to a toxic level in body tissues and for the maintenance of pH homeostasis.

Decomposition of fine roots of Pinus kesiya and turnover of organic matter, N and P of coarse and fine pine roots and herbaceous roots and rhizomes in subtropical pine forest stands of different ages

Abstract: Organic matter accumulation, N and P concentrations of fine (<2 mm diameter) and coarse (2–10 mm) roots of Pinus kesiya and fine roots and rhizomes of ground vegetation, and decomposition of P. kesiya fine roots (<2 mm diameter) were studied in 6-, 15- and 23-year-old P. kesiya forest stands at Shillong, the capital of Meghalaya, India. The mean annual dry weight of P. kesiya fine roots did not vary significantly between the stands, but the coarse root mass increased significantly from the 6- to 23-year-old stand. However, herbaceous fine roots and rhizomes showed a reverse trend. Live roots (biomass) showed a higher N and P concentration than the necromass (dead root mass). Nutrient concentrations were greater in the fine roots compared to coarse roots. N and P accumulation was maximum in the 6-year-old stand and minimum in the 15-year-old stand. P. kesiya fine roots decomposed in a three-phased manner in all the stands. The first phase, lasting about 30 days, was characterised by a slow rate of weight loss. This was followed by a rapid phase of weight loss up to 90 days, with an average weight loss of 7.7 mg day–1, and the third phase showed a slow decay pattern (1.2 mg day–1). The weight loss pattern showed a strong seasonal trend; a faster rate of decay in the warm-humid period and a slow rate of decay in the dry-cold period. Nitrogen and P concentration in the decomposing root litter showed a marked decrease and/or increase during decomposition. The study reveals that in the 6-year-old pine stand the roots of herbaceous plants play a more significant role in maintaining the organic matter, N and P status of the soil, while in the older stands pine roots assumed greater significance.

Changes in glutathione-related enzymes in tumor-bearing mice after cisplatin treatment.

Abstract: The effect of cisplatin on five glutathione-related enzymes was studied in liver, kidney, and Dalton lymphoma cells of tumor-bearing mice. In liver, the activities of glutathione S-transferase, glutathione peroxidase, catalase, and superoxide dismutase decreased approximately 30-40%, 60-67%, 35-50% and 70-80% respectively, while glutathione reductase increased about 36-45% after cisplatin treatment. In kidney, catalase activity decreased by 47-82% at all time points (24-96 h) of cisplatin treatment, while glutathione S-transferase activity decreased significantly (approximately 24%) mainly at 72 h of treatment. An increase in glutathione reductase (approximately 1.5-2.5 times), glutathione peroxidase (significant at 24 h, 47%), and superoxide dismutase (approximately 15-60%) was noted in kidney after the treatment. In Dalton lymphoma cells, the activities of glutathione S-transferase, glutathione peroxidase, and catalase decreased very distinctly (approximately 2-5, 2-5 and 5-11 times, respectively) at all time points, but glutathione reductase decreased significantly only at 72 h of cisplatin treatment. Interestingly, the superoxide dismutase activity in Dalton lymphoma cells increased initially at 24-48 h and then decreased (approximately 60%) during later periods (72-96 h) of treatment. Cisplatin treatment caused a decrease in glutathione level in Dalton lymphoma cells (approximately 14-20%) and kidney (approximately 18-28%) but no change in liver. In view of the results, a definite correlation with the changes in glutathione concentrations and enzymatic activities in a tissue could not be firmly derived. It is suggested that the changes in various glutathione-related enzymes and glutathione levels in the tissues of the host during cisplatin-mediated chemotherapy could affect cellular antioxidant defense potential, which may play an important contributory role in cisplatin-mediated toxicity, particularly nephrotoxicity, and anticancer activity in the host.

Fenvalerate-induced chromosome aberrations and sister chromatid exchanges in the bone marrow cells of mice in vivo

Abstract: Fenvalerate, a synthetic pyrethroid insecticide, is commonly used in agriculture and other domestic applications due to its high insecticidal activity and low mammalian-, avian- and phyto-toxicities However, the genotoxic effect of fenvalerate is highly equivocal In the present study the genotoxic effects of fenvalerate was evaluated using structural chromosome aberration (CA) and sister chromatid exchange (SCE) assays in mice Out of the three doses (5, 10 and 20 mg/kg) tested, statistically significant increase in CA was found following intra peritoneal (ip) treatment of 20 mg/kg of fenvalerate for 24 h (P 5×4 mg / kg ) of fenvalerate could induce any significant effect All the three acute doses induced significant increase in the frequency of SCEs (P

Sialic acid changes in Dalton's lymphoma-bearing mice after cyclophosphamide and cisplatin treatment.

Abstract: Sialic acid changes in Dalton's lymphoma cells and other tissues of 10-12-week-old Swiss albino mice were investigated in relation to tumour growth in vivo and following cyclophosphamide (ip, 200 mg/kg body weight) or cisplatin (ip, 8 mg/kg body weight) treatment. Three to four animals of both sexes were used in each experimental group. The sialic acid level of tumour cells (0.88 micromol/g) increased with tumour progression (1.44-1.59 micromol/g; P < or =0.05) in mice. Sialic acid concentration in other tissues (liver, kidney, testes and brain) also increased (approximately 40, 10, 30 and 58%, respectively) in the tumour-bearing hosts as compared with that in the respective tissues of normal mice. In vivo cyclophosphamide or cisplatin treatment resulted in an overall decrease of sialic acid contents in the tissues. Cyclophosphamide was more efficient in lowering tissue sialic acid than cisplatin (P < or =0.01, ANOVA). It is suggested that sialic acid residues could be an important factor contributing to the manifestation of malignant properties in cancer cells in general and Dalton's lymphoma cells in particular. A significant decrease in the sialic acid content of Dalton's lymphoma cells after cisplatin or cyclophosphamide treatment may bring about specific changes in tumour cells which could be associated with tumour regression.

Antiproliferative and cytotoxic effect of a novel organotin compound on mammalian cells both in vitro and in vivo.

Abstract: Organotin compounds are organometallic compounds showing various toxicological properties. Several organotin compounds also showed an antineoplastic effect. However, their relative mutagenic potential is not well established. In this study Et(2)SnCl(2).L [L=N-(2-pyridylmethylene)-4-toluidine] (OTC) has been subjected to investigation for its cytotoxic effect in mouse bone marrow cells (BMCs) and human peripheral blood lymphocyte cells (HPBLs). The Sn [bond] N bond in OTC is 2.46A which is greater than 2.39A and therefore, a better formation of tin-DNA complex can be expected. The present data indicate that OTC induced significant delay in cell kinetics and sister chromatid exchanges (SCEs) in both BMCs and HPBLs, whereas, induction of chromosome aberrations was found only in HPBLs. The presence of buthionine sulfoximine (BSO) modulated cellular sensitivity towards OTC in both cell systems. It may be inferred that the OTC could bind on DNA more easily owing to its structural advantage and this may explain the induction of DNA damage and the delay in cell proliferation. Since the cytotoxic effect of OTC is more in glutathione depleted cells, the concentration of OTC may be reduced to get an antitumour effect in GSH-depleted cells and thus minimizes its toxic side effect.

Sparticle spectrum and constraints in anomaly mediated supersymmetry breaking models

Abstract: We study in detail the particle spectrum in anomaly mediated supersymmetry breaking models in which supersymmetry breaking terms are induced by the super-Weyl anomaly. We investigate the minimal anomaly mediated supersymmetry breaking models, gaugino assisted supersymmetry breaking models, as well as models with additional residual nondecoupling D-term contributions due to an extra U(1) gauge symmetry at a high energy scale. We derive sum rules for the sparticle masses in these models which can help in differentiating between them. We also obtain the sparticle spectrum numerically, and compare and contrast the results so obtained for the different types of anomaly mediated supersymmetry breaking models.

Proton induced modification in Poly(ethylene terephthalate)

Abstract: The effect of 100 kGy dose of 2 MeV electron irradiation on Poly(ethylene terepthalate) (PET) has been studied by different characterisation techniques such as the Fourier transformed IR spectroscopy, electron spin resonance spectroscopy, thermogravimetric analysis, differential scanning calorimetry and X-ray diffraction analysis. Oxidative degradation leading to amorphisation of the polymer has been observed from spectral analysis. The thermal stability of the polymer was found to decrease due to electron irradiation. The thermal decomposition temperature as well as the melting temperature in case of irradiated PET was found to be decreased due to electron bombardment. A decrease in crystallinity of the polymer has also been observed after irradiation.

Genetic relationships among some tribal groups inhabiting the north‐eastern, eastern and sub‐Himalayan regions of India

Abstract: The origins and genomic affinities of various tribal populations of India are of considerable contemporary interest. In this study, we have investigated relationships among five tribal groups inhabiting the north-eastern, eastern and sub-Himalayan regions of India. DNA samples have been analysed in respect of 25 polymorphic loci, based on which genetic affinities have been estimated. The interesting findings of this study are (i) the Tibeto-Burman speaking, morphologically Mongoloid, tribal groups of India are not genetically very homogeneous, and (ii) the Tharu, a group inhabiting the sub-Himalayan region, may indeed have undergone considerable admixture as has been postulated by some anthropologists.

Kinetics of the Oxidation of Heterocyclic Aldehydes by Quinolinium Dichromate

Abstract: Quinolinium dichromate in sulfuric acid oxidizes heterocyclic aldehydes (2-furaldehyde, 2-pyrrolecarbaldehyde, 2-thiophenecarbaldehyde) to the corresponding acids in a 50% (v/v) acetic acid–water medium. The kinetic data on the rates of oxidation of the substrates have been discussed with reference to the aldehyde hydration equilibria. The kinetic results support a mechanistic pathway proceeding via a rate-determining oxidative decomposition of the chromate ester of the aldehyde hydrate.

Above-barrier resonances: analytical expressions for energy and width

Abstract: We construct a smooth realistic barrier potential that can generate resonances above the top of the barrier provided a parameter λ controlling the flatness of the barrier is larger than the critical value λ = (2)1/2. The energies and widths of resonances are expressed analytically in terms of the characteristics of the barrier, namely height, range and flatness. In order to obtain a more versatile and asymmetric barrier, two symmetric barriers are merged together side by side and the exact transmission coefficient across such a barrier is derived.

Development of molecular markers for screening of Alnus nepalensis (D. Don) genotypes for the nitrogenase activity of actinorhizal root nodules.

Abstract: Alnus nepalensis (D. Don), an alder species, is an actinorhizal tree found in the hilly regions of Eastern and Northeastern India. It is useful in the reclamation of wastelands generated by land slips, shifting agriculture and coal mining. To maximise the soil regeneration capacity of alder plantations, it would be useful to be able to select superior alder genotypes at the nursery level. Conventional methods of genotype screening are difficult to apply to open-pollinated forest trees. It would be beneficial if molecular markers could be developed for early screening. The study reported here was conducted to assess the feasibility of developing PCR-based AFLP and RFLP screening tools for the selection of superior genotypes of this valuable tree with respect to their ability to support efficient nitrogen-fixing root nodules. It was found that a multi-site strategy, including the chloroplast rrn operon and the nuclear rRNA genes, yielded promising results. A molecular marker for genotypes that support nodules with low nitrogenase activity was also identified.