http://nopr.niscair.res.in/handle/123456789/3448 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/3503 Title: A simplified fluorimetric method for corticosterone estimation in rat serum, tissues and mitochondria <br/> <br/>Authors: Katyare, Surendra S; Pandya, Jignesh D <br/> <br/>Abstract: A simplified procedure has been developed for the extraction and estimation of corticosterone from rat serum, tissues and mitochondria. The suitably diluted samples were treated with freshly prepared chloroform: methanol mixture (2:1, v/v) and then extracted directly with the chloroform. Almost quantitative recoveries (90% and above) were obtained with the present method, compared to poor recoveries (65-81%) and variable results obtained by earlier procedure. Quantification of corticosterone content in tissues, such as liver, brain and heart, and in the mitochondria indicated significant concentration of corticosterone in tissues and mitochondria, as compared to the serum. The presence of corticosterone in the mitochondria suggests that the hormone may play a role in regulation of mitochondrial gene expression and/or their turnover <br/> <br/>Page(s): 48-53 Sat, 29 Jan 2005 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/3502 Title: Role of MMP-2 in oxidant-mediated regulation of Ca²⁺ uptake in microsomes of bovine pulmonary artery smooth muscle <br/> <br/>Authors: Mandala, Amritlal; Chakrabortia, Tapati; Choudhurya, Rajdeep; Ghosha, Biswarup; Chakrabortia, Sajal <br/> <br/>Abstract: Treatment of bovine pulmonary artery smooth muscle microsomes with tert-butylhydroperoxide (t-buOOH) (300 µM) markedly stimulated matrix metalloproteinase-2 (MMP-2) activity and enhanced Ca²⁺-ATPase activity and ATP-dependent Ca²⁺ uptake. Pre-treatment with vit. E (1 mM) and tissue inhibitor of metalloproteinase-2 (TIMP-2) (50 µg/ml) prevented t-buOOH-induced stimulation of MMP-2 activity, Ca²⁺-ATPase activity and ATP-dependent Ca²⁺ uptake. In contrast, Na⁺-dependent Ca²⁺ uptake was inhibited by t-buOOH and the inhibition was reversed by vit. E (1 mM) and TIMP-2 (50 µg/ml). However, t-buOOH-triggered changes in MMP-2 activity, and ATP- and Na+-dependent Ca²⁺ uptake were not reversed upon pre-treatment of the microsomes with a low concentration of 5 µg/ml of TIMP-2, which on the contrary reversed MMP-2 (1 µg/ml)-mediated alteration on these parameters. The inhibition of Na+-dependent Ca²⁺ uptake by MMP-2 under t-buOOH treatment overpowered the stimulation of ATP-dependent Ca²⁺ uptake in the microsomes. Combined treatment of the microsomes with low doses of MMP-2 (0.5 µg/ml) and t-buOOH (100 mM) augmented Ca²⁺-ATPase activity and ATP-dependent Ca²⁺ uptake, but inhibited Na+-dependent Ca²⁺ uptake, compared to that elicited by either MMP-2 (0.5 µg/ml) or t-buOOH (100 µM). Pre-treatment with TIMP-2 (50 µg/ml) reversed the effects of MMP-2 (0.5 µg/ml) and/or t-buOOH (100 mM). Although pre-treatment with 5 µg/ml of TIMP-2 reversed the effects produced by MMP-2 (0.5 µg/ml), but it did not inhibit the responses elicited by t-buOOH (300 µM) or t-buOOH (100 mM) plus MMP-2 (0.5 mg/ml) in the microsomes. Treatment with TIMP-2 (5 mg/ml) inhibited MMP-2 (1 mg/ml) activity (assessed by [14C]-gelatin degradation), whereas treatment of t-buOOH (300 µM) with TIMP-2 (5 µg/ml) abolished the inhibitory effect of TIMP-2 (5 µg/ml) on MMP-2 (1 µg/ml) activity (assessed by [14C]-gelatin degradation). Overall, these results suggested that t-buOOH inactivated TIMP-2, the ambient inhibitor of MMP-2, leading to activation of the ambient proteinase, MMP-2 which subsequently stimulated Ca²⁺-ATPase activity and ATP-dependent Ca²⁺ uptake, but inhibited Na⁺-dependent Ca²⁺ uptake, resulting in a marked decrease in Ca²⁺ uptake in the microsomes. <br/> <br/>Page(s): 19-27 Sat, 29 Jan 2005 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/3501 Title: Binding of heme to human serum albumin: Steady-state fluorescence, circular dichroism and optical difference spectroscopic studies <br/> <br/>Authors: Kamal, J K Amisha; Behere, Digambar V <br/> <br/>Abstract: The binding of monomeric heme to human serum albumin (HSA) was investigated using steady-state fluorescence, circular dichroism (CD) and optical difference spectroscopic (ODS) techniques. The existence of one strong binding site for heme on HSA was confirmed by titrating heme with HSA and following the quenching of tryptophan (Trp214) fluorescence emission intensity that occurred due to energy transfer. Up to around 1:1 stoichiometric ratio of HSA/heme, the quenching was observed to be very strong, however at higher ratios the quenching progressed very weakly. Similarly, the negative CD band centered at ~397 nm, which appeared on adding heme to HSA, increased in intensity on sequential addition of heme up to [heme]/[HSA]=1. Titration of HSA with heme was followed by ODS and the dissociation constant KD = (4.0±1.0)×10⁻⁵ M was deduced. Results have been explained on the basis of Michaelis-Menton type of mechanism for the heme binding, in which heme first binds reversibly to His146 at the surface of the protein to form an intermediate complex, followed by irreversible binding to Tyr161 in the interior of the protein <br/> <br/>Page(s): 7-12 Sat, 29 Jan 2005 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/3500 Title: Oxidative stress in paracetamol-induced pathogenesis: (I) Renal damage <br/> <br/>Authors: Abraham, Premila <br/> <br/>Abstract: The effect of administration of paracetamol (1 g/kg body wt) on oxidative damage to proteins and lipids in the kidney was studied at various time intervals in adult male Wistar rats. Iindicators of oxidative stress, such as protein thiol, protein carbonyl content and lipid peroxide levels were assayed along with thiol-dependent enzyme activities, glutamine synthase and glyceraldehyde-3-phosphate dehydrogenase. Paracetamol-induced renal damage after 4 hr of administration was evidenced by elevation in plasma creatinine levels and the presence of acute tubular necrosis on histological examination of the kidney. No significant change in any other parameters was observed, except for decreased glutathione level. An increase in lipid peroxide level was observed at 24 hr after treatment. The results suggest that oxidative stress may not play a causative role, but contribute to the pathogenesis of paracetamol-induced renal damage. <br/> <br/>Page(s): 59-62 Sat, 29 Jan 2005 22:58:59 GMT