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601.
602.
Summary The paper deals with the first report of the predacious fungusAcaulopage pectospora
Drech. from Indian soils. The fungus has been studied both in culture and on soil and decaying leaves. The predatory, morphological and reproductive characters of the fungus has been described along with illustrative diagrams. 相似文献
603.
In this paper we consider a modification of Bailey's stochastic model for the spread of an epidemic when there are seasonal variations in infection rate. The resulting nonlinear model is analyzed by employing the diffusion approximation technique. We have shown that for a large population the process, on suitable scaling and normalization, converges to a non-stationary Ornstein-Uhlenbeck process. Consequently the number of infectives has in the steady state a gaussian distribution. 相似文献
604.
Ajay Kumar N. Usha P. D. Sawant R. M. Tripathi Sanu S. Raj Manish Mishra 《人类与生态风险评估》2011,17(2):381-393
Traces of uranium were measured by laser fluorimeter in 235 subsurface water samples collected from four districts of Punjab state in India. The concentration of U in water samples ranged between <2–644 μg/L with a mean value of 73.1 μg/L. The radiological risk was observed to be in the range of 5.55 × 10?6–1.78 × 10?3 with a mean value of 2.03 × 10?4, which is around 22% more than the maximum acceptable level (l.67 × 10?4) as per guidelines of India's Atomic Energy Regulatory Board. The mean of chemical toxicity risk, expressed as life time average daily dose (LADD) was worked out to be 5.56 μg/kg/day with a range of 0.15–48 μg/kg/day by considering a bodyweight of 51.5 ± 8.5 kg, water ingestion rate of 4.05 L/d, and life expectancy of 63.7 yrs for an adult Indian reference man and compared with the reference dose (4.53 μg/kg/day). The average exposure level of U was comparatively high and the chemical toxicity was expected to be more. The mean of hazard quotient (LADD/ RfD) for all four districts was found to be greater than 1, indicating that groundwater may not be suitable for consumption from a chemical toxicity point of view. 相似文献
605.
Ruchi Srivastava Jayantee Kalita Mohammad Yahiya Khan Usha Kant Misra 《Neurochemical research》2009,34(12):2141-2146
Increased generation of free radicals resulting in brain injury is a feature of many viral infections. The present study has
been undertaken to evaluate the level of free radicals in Japanese encephalitis. Twelve days old Wistar rats were inoculated
intracerebrally with 3 × 106 pfu of JE virus and were sacrificed on 3, 6, 10, and 20 days post inoculation (dpi). The neuronal levels of reactive oxygen
species (ROS), nitric oxide (NO), peroxinitrite (OONO−), necrotic and apoptotic cell population were estimated by flow cytometry. Hematoxylin-eosin staining was also performed.
Maximum level of neuronal ROS and OONO− was observed on 6 dpi; however, NO levels peaked on 10 dpi. Free radical generation significantly declined on 20 dpi as compared
to control. Apoptotic cell death gradually increased over the time. Neuronal shrinkage and necrosis was also observed. The
results of our study indicate that free radicals increased in acute JE and declined at later stage, which may contribute to
cell death. 相似文献
606.
Oxidative DNA damage in tissues of English sole (Parophrys vetulus) exposed to nitrofurantoin 总被引:1,自引:0,他引:1
Marc Nishimoto William T. Roubal John E. Stein Usha Varanasi 《Chemico-biological interactions》1991,80(3):317-326
Juvenile English sole were exposed intramuscularly to nitrofurantoin (NF) and the levels of 8-hydroxy-2′deoxyguanosine (8-OH-dG) in liver, kidney and blood were determined using reversed-phase HPLC with electrochemical detection. Identification and quantitation of the 8-OH-dG in the samples was accomplished by comparison with standard 8-OH-dG, which was characterized by UV spectroscopy and fast-atom bombardment mass spectrometry. The levels of hepatic 8-OH-dG increased (r2 = 0.59, P = 0.015) with the dose of NF (0.10 – 10 mg NF/kg fish). In kidney and blood, however, the levels of 8-OH-dG were significantly higher than controls only at the highest dose tested. The level of binding in liver ranged from 0.37 to 0.76 fmol 8-OH-dG/μg DNA. The levels of hepatic 8-OH-dG reached a maximum (approx. 1 fmol 8-OH-dG/μg DNA) between 1 and 3 days after exposure, followed by a decrease to control levels (approx. 0.25 fmol 8-OH-dG/μg DNA) at 5 days post-exposure. These data demonstrate the first direct evidence for the formation of oxidized DNA bases resulting from the metabolism of a nitroaromatic compound by fish. 相似文献
607.
Ammonia or Ammonium Ion as Substrate for Oxidation by Nitrosomonas europaea Cells and Extracts 总被引:12,自引:2,他引:10 下载免费PDF全文
The effect of pH on the K(m) values for ammonia was studied in its oxidation by Nitrosomonas cells and cell-free extracts. The K(m) values decreased markedly with increasing pH, suggesting (NH(3)) rather than (NH(4) (+)) as the actual substrate for oxidation. 相似文献
608.
Usha Natraj 《Journal of biosciences》1988,13(3):275-283
Luteinizing hormone is known to stimulate the enzyme ornithine decarboxylase in the ovary. Highly purified human follicle
stimulating hormone that is devoid of significant biologically active luteinizing hormone can also induce ornithine decarboxylase
activity in intact immature rats with a time course of induction similar to that reported for luteinizing hormone. A maximum
of 8–10-fold stimulation above controls was observed 4 h following intravenous administration of human follicle stimulating
hormone. This stimulation followed a strict dose response relationship. Ovine luteinizing hormone and human chorionic gonadotropin
always induced more ovarian ornithine decarboxylase activity than that achieved by maximally effective doses of follicle stimulating
hormone. This could not be attributed solely to the ability of specific cell population to respond to the respective gonadotropins.
Although granulosa cells contained little receptor for luteinizing hormone/human chorionic gonadotropin and the residual tissue
contained little receptor for follicle stimulating hormone, each tissue responded to these gonadotropins in a manner suggestive
of the mediation by one or more diffusable factors. A relationship between gonadotropin induced 3’5’-cyclic adenosine monophosphate
(cyclic adenosine monophosphate) concentration and ornithine decarboxylase activity suggests that the mediation of gonadotropin
stimulated ovarian ornithine decarboxylase is not solely through cyclic adenosine monophosphate, indicating the presence of
other factors in the induction of gonadotropin increased ornithine decarboxylase activity. 相似文献
609.
The antioxidative and/or pro-oxidative potential of three trace metal ions, namely aluminum (Al), manganese (Mn), and selenium
(Se), has been studied. The effect of Al and Mn was found to be anion independent. The pro-oxidative potential of Al was more
prominent than its antioxidative potential. This may be due to its redox inert nature. The increase in lipid peroxidation
rates in placental syncytiotroblast membranes may contribute to the etiology of aluminum toxicity. Selenium had an antioxidative
potential only in the whole-cell homogenate. This appears to be mediated by glutathione peroxidase of which Se is a cofactor.
Manganese proved to be the trace metal ion of choice. It decreased the production of thiobarbituric acid reactive substances
(TBARS). This may be due to its capacity to quench the superoxide anion and hydroxyl radicals and also due to its chain-breaking
capacity. During the present course, ferrous-ascorbate mediated lipid peroxidation has been studied using various combinations
of FeSO4 and ascorbic acid. Extrapolating the combined ratio of the individual combination as substrate concentration ([S]) and treating
the observed amount of malondialdehyde (MDA) produced equivalent to initial velocity (v
i
), as in the case of enzymatic studies, the data were treated according to Michaelis-Menten kinetics and the values of k
c
and C
max have been calculated. 相似文献
610.
Sarkar Jayanwita Chakraborty Bishwanath Chakraborty Usha 《Journal of Plant Growth Regulation》2018,37(4):1396-1412
Journal of Plant Growth Regulation - In India and other tropics, wheat plants suffer from exposure to high temperature with heat increase above 35 °C causing stress-like conditions.... 相似文献