Jawaharlal Nehru University

About: Jawaharlal Nehru University is a education organization based out in New Delhi, India. It is known for research contribution in the topics: Population & Politics. The organization has 6082 authors who have published 13455 publications receiving 245407 citations. The organization is also known as: JNU.

Lipid peroxidation and glutathione peroxidase, glutathione reductase, superoxide dismutase, catalase, and glucose-6-phosphate dehydrogenase activities in FeCl3-induced epileptogenic foci in the rat brain.

Abstract: This study investigated the relationship between lipid peroxidation, subsequent activation of antioxidative enzymes, and development of iron-induced epilepsy in the rat. Epileptic foci were produced in rat cerebral cortex by intracortical injection of ferric chloride (FeCl3). The epileptic foci were identified by electrocorticography (ECoG). Epileptiform ECoG activity was shown to occur in the contralateral homotopic cerebral cortex as well. We measured levels of lipid peroxides and changes in the activities of the enzymes: superoxide dismutase (SOD), glutathione peroxidase (GP), glutathione reductase (GR), catalase (CA), and glucose-6-phosphate dehydrogenase (G6P) in the epileptogenic focus (both ipsilateral and contralateral) at days 3, 8, 15, and 23 after FeCl3 injection. Biochemical estimations were made in subcellular fractions, and changes in the ipsilateral site were compared with those in the contralateral site. The results of this study showed that large increases in lipid peroxidation were associated with development and buildup of the ECoG epileptiform discharges. Lipid peroxides increased in the ipsilateral focus by approximately 100% as compared with control. In the contralateral site, however, the increase in lipid peroxides was marginal only. The increase in lipid peroxidation was concomitant with development of the high level of epileptiform activity. The time course of changes in lipid peroxidation paralleled the time course of development and persistence of the epileptiform activity. Regarding changes in the enzyme activities accompanying development of iron epilepsy, the data showed that although SOD and G6P increased by approximately 60% and GR increased by approximately 40%, the increases in the enzyme GP and CA were much lower, less than 20%. Thus, comparatively less increase in CA and GP activities produces a deficiency of these two enzymes in the iron (ipsilateral) focus. Among the various biochemical disturbances that have been identified as involved in epileptogenesis, peroxidative injury resulting from lipid peroxidation in neural plasma membrane may be causally related to development of paroxysmal epileptiform activity in the iron focus. Since GP is an enzyme of major importance in detoxification of lipid peroxides in the brain, based on the results presented in this article, it appears reasonable to suggest that GP deficiency causes lipid peroxidation to increase tremendously during iron epileptogenesis.

Terrestrial cosmogenic nuclide surface exposure dating of the oldest glacial successions in the Himalayan orogen: Ladakh Range, northern India

Abstract: Terrestrial cosmogenic nuclide surface exposure dating of moraine boulders and alluvial fan sediments define the timing of five glacial advances over at least the last five glacial cycles in the Ladakh Range of the Transhimalaya. The glacial stages that have been identified are: the Indus Valley glacial stage, dated at older than 430 ka; the Leh glacial stage occurring in the penultimate glacial cycle or older; the Kar glacial stage, occurring during the early part of the last glacial cycle; the Bazgo glacial stage, at its maximum during the middle of the last glacial cycle; and the early Holocene Khalling glacial stage. The exposure ages of the Indus Valley moraines are the oldest observed to date throughout the Himalayan orogen. We observe a pattern of progressively more restricted glaciation during the last five glacial cycles, likely indicating a progressive reduction in the moisture supply necessary to sustain glaciation. A possible explanation is that uplift of Himalayan ranges to the south and/or of the Karakoram Mountains to the west of the region may have effectively blocked moisture supply by the south Asian summer monsoon and mid-latitude westerlies, respectively. Alternatively, this pattern of glaciation may reflect a trend of progressively less extensive glaciation in mountain regions that has been observed globally throughout the Pleistocene.

Involvement of proline in protecting thylakoid membranes against free radical-induced photodamage

Abstract: Investigations were carried out to determine the involvement of proline in protecting thylakoid membranes against photodamage. The exposure of thylakoids isolated from the cotyledons of Brassica juncea to photoinhibitory light caused a linear increase in lipid peroxidation with time as measured by the assay of conjugated dienes and malondialdehyde (MDA). Proline produced a considerable reduction in the lipid peroxidation-linked formation of both conjugated dienes and MDA in the thylakoids during exposure to strong light. This reduction in lipid peroxidation reflects the probable involvement of proline in the reduction of the free radicals generated on strong light exposure. The thylakoids exposed to strong light intensity also generated singlet oxygen (1O2) and superoxide radical anion (O2−1). The level of these radicals increased with the time of exposure. The presence of proline significantly curtailed the production of 1O2 by the thylakoids during strong illumination. However, the presence of proline did not affect the O2− induction capacity of the thylakoid membranes during strong light exposure. Peroxidation of linolenic acid micelles occurred on exposure to UV radiation. The almost total suppression of UV-induced lipid peroxidation of linolenic acid micelles in the presence of sodium azide and L-histidine (singlet oxygen quenchers) suggested the involvement of 1O2 in UV-induced lipid peroxidation. The presence of proline during the exposure of linolenic acid micelles to UV radiation caused a considerable reduction in the formation of conjugated dienes as well as MDA. The proline-induced reduction in the peroxidation of these micelles further confirms the involvement of proline in reducing the level of 1O2. Our results therefore demonstrate that proline is involved in reducing the photodamage in the thylakoid membranes by scavenging and/or reducing the production of 1O2.

From balance to imbalance: a shift in the dynamic behaviour of Chhota Shigri glacier, western Himalaya, India

Abstract: Mass-balance and dynamic behaviour of Chhota Shigri Glacier have been investigated between 2002 and 2010 and compared to data collected in 1987/1989. During the period 2002/2010, the glacier experienced a negative glacier-wide mass balance of -0.67 ± 0.40 m/a w.e. Between 2003 and 2010, elevation and ice flow velocities are slowly decreasing in the ablation area leading to a 24 to 37% reduction in ice fluxes, an expected response of the glacier dynamics to its recent negative mass balances. The reduced ice fluxes still remain far larger than the balance fluxes calculated from the year 2002 to 2010 average surface mass balances. Therefore, further slow down, thinning and terminus retreat of Chhota Shigri Glacier are expected over the next years. Conversely, the 2003/2004 ice fluxes are in good agreement with ice fluxes calculated assuming that the glacier-wide mass balance is zero. Given the limited velocity change between 1987/1989 and 2003/2004 and the small terminus change between 1988 and 2010, we suggest that the glacier has experienced a period of near zero or slightly positive mass balance in the 1990s, before shifting to a strong imbalance in the 21st century. This result challenges the generally accepted idea that glaciers of Western Himalaya have been shrinking rapidly for the last decades.