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41.
Anjaneyulu Kowluru 《Journal of cellular and molecular medicine》2008,12(1):164-173
Insulin secretion from the pancreatic beta-cell is regulated principally by the ambient concentration of glucose. However, the molecular and cellular mechanisms underlying the stimulus-secretion coupling of glucose-stimulated insulin secretion (GSIS) remain only partially understood. Emerging evidence from multiple laboratories suggests key regulatory roles for GTP-binding proteins (G-proteins) in the cascade of events leading to GSIS. This class of signaling proteins undergo a series of requisite post-translational modifications (e.g., prenylation) at their C-terminal cysteines, which appear to be necessary for their targeting to respective membranous sites for optimal interaction with their respective effector proteins. This communication represents a perspective on potential regulatory roles for protein prenylation steps (i.e., protein farnesylation and protein geranylgeranylation) in GSIS from the islet beta cell. Possible consequences of protein prenylation and potential mechanisms underlying glucose-induced regulation of prenylation, specifically in the context of GSIS are also discussed. 相似文献
42.
Chemical examination of the ethyl acetate solubles of the CH3OH:CH2Cl2 (1:1) extract of the roots of Ceriops decandra collected from Kauvery estuary resulted in the isolation of four new diterpenoids, ceriopsins A–D (1–4). The structures of the new diterpenoids were elucidated by a study of their physical and spectral data as methyl 17-hydroxy-16-oxobeyeran-18-oate (1), methyl 16(R)-16,17-dihydroxybeyeran-18-oate (2), 1β,15(S)-isopimar-7-ene-1,15,16-triol (3), and 8,15(R)-epoxypimarane-1β,16-diol (4). 相似文献
43.
Addition of bovine adrenal cytochrome P-450scc to small unilamellar dioleoylphosphatidylcholine vesicles (DOPC-SUV) produces a complex sequence of interactions, indicating exceptional cytochrome mobility. First, cholesterol transfer from cytochrome to vesicles indicated rapid dissociation of P-450scc oligomers and integration of monomers into the membrane (delta A 390-420 nm; t1/2 = 2 s). After 10-15 s, P-450scc-induced aggregation of the vesicles starts, as indicated by increased turbidity (delta A 448 or 520 nm; complete in 6-8 min). Fluorescence quenching experiments indicate that this aggregation does not lead to measurable vesicle fusion during this period. Aggregation is prevented by mild heat denaturation of P-450scc, by addition of anti-P-450scc IgG, and also by 1:1 complex formation with the electron donor adrenodoxin (ADX). P-450scc, therefore, links two vesicles through two separate domains involved in, respectively, membrane integration (lipophilic) and ADX binding (charged). Although completely bound by DOPC-SUV, as evidenced by Sephadex elution, P-450scc has access within 1 min to cholesterol in secondary SUV. This is indicated by spectral changes (cholesterol complex formation) and by metabolism of secondary vesicle cholesterol. Since cholesterol equilibrates slowly between vesicles (t1/2 = 1-2 h), these changes arise from P-450scc transfer. This transfer was maximally slowed after a 5-min preincubation with primary vesicles, reflecting more extensive integration into the membrane than is necessary for the rapid initial cholesterol transfer to P-450scc. P-450scc transfer probably results from simultaneous interaction of P-450scc with two vesicles that may also initiate aggregation. Weaker integration into primary dimyristoylphosphatidylcholine vesicles facilitates exchange but prevents aggregation. Integration and aggregation are both enhanced by incorporation of 10% phosphatidylinositol into SUV, while exchange is slowed. This mobility of P-450scc is most probably a consequence of the absence of amino-terminal anchoring. P-450scc-induced association of inner mitochondrial membrane segments may contribute to the exceptionally vesiculated structure of adrenal and ovarian mitochondria that parallels increased P-450scc content. 相似文献
44.
D. Sreekanth D. Sivaramakrishna V. Himabindu Y. Anjaneyulu 《Bioresource technology》2009,100(9):2534-2539
The hybrid up flow anaerobic sludge blanket reactor was evaluated for efficacy in reduction of chemical oxygen demand (COD) and biochemical oxygen demand (BOD) of bulk drug pharmaceutical wastewater under different operational conditions. The start-up of the reactor feed came entirely with glucose, applied at an organic loading rate (OLR) 1 kg COD/m3 d. Then the reactor was studied at different OLRs ranging from 2 to 11 kg COD/m3 d with pharmaceutical wastewater. The optimum OLR was found to be 9 kg COD/m3 d, where we found 65–75% COD and 80–94% of BOD reduction with biogas production containing 60–70% of methane and specific methanogenic activity was 320 ml CH4/g-VSS d. By the characterization studies of effluent using GC–MS, the hazardous compounds like phenol, l,2-methoxy phenol, 2,4,6-trichloro phenol, dibutyl phthalate, 1-bromo naphthalene, carbamazepine and antipyrine were present. After the treatment, these compounds degraded almost completely except carbamazepine. Thermophilic methanothrix and methanosaetae like bacteria are present in the granular sludge. 相似文献
45.
Neuropathic pain is one of the important microvascular complications of diabetes. Oxidative stress and superoxide play a critical role in the development of neurovascular complications in diabetes. Aim of the present study was to evaluate the effect of quercetin, a bioflavonoid on thermal nociceptive responses in streptozotocin (STZ)-induced diabetic rats assessed by tail-immersion and hot plate methods. After 4-weeks of a single intravenous STZ injection (45 mg/kg body weight), diabetic rats exhibited a significant thermal hyperalgesia and cold allodynia along with increased plasma glucose and decreased body weights as compared with control rats. Chronic treatment with quercetin (10 mg/kg body weight; p.o) for 4-weeks starting from the 4th week of STZ-injection significantly attenuated the cold allodynia as well as hyperalgesia. Results indicate that quercetin, a natural antioxidant, may be helpful in diabetic neuropathy. 相似文献
46.
Veluthakal R Amin R Kowluru A 《American journal of physiology. Cell physiology》2004,287(4):C1152-C1162
We examined the effects of interleukin-1 (IL-1) treatment on the distribution and degradation of lamin B in the nuclear fraction from insulin-secreting RINm5F cells. Western blot analysis indicated that IL-1 treatment caused significant alterations in the redistribution of lamin B, specifically between the Triton X-100-soluble (membrane) and -insoluble (matrix) fractions of the nucleus. IL-1 treatment also increased the lamin carboxymethyltransferase activity and the relative abundance of the carboxymethylated lamin in the nuclear fraction. A significant increase in the relative abundance of lamin B degradation products was also observed in the nuclear fraction from the IL-1-treated cells. These findings are compatible with a measurable increase in the lamin-degrading caspase-6 activity in IL-1-treated cells. Confocal microscopic observation of IL-1-treated cells suggested a significant dissociation of lamin B from the nuclear lamina and its subsequent association with the DNA-rich elements within the nucleus. NG-monomethyl-L-arginine, a known inhibitor of inducible nitric oxide synthetase (iNOS), markedly inhibited IL-1-induced iNOS gene expression, NO release, caspase-3 and caspase-6 activation, lamin B degradation, and loss of metabolic cell viability, indicating that the observed IL-1-induced effects on nuclear lamin B involve the intermediacy of NO. Together, our data support the hypothesis that IL-1 treatment results in significant increase in the carboxymethylation of lamin B, which would place lamin B in a strategic location for its degradation mediated by caspases. This could possibly lead to dissolution of the nuclear envelope, culminating in the demise of the effete -cell. pancreatic -cell; lamin carboxymethyltransferase; nitric oxide; nuclear matrix; caspases 相似文献
47.
From the neutral fraction of the n-hexane extract of stem bark of Mangifera indica, (var./cv Banganpalli) six new tetracyclic triterpenoids, cycloart-24-ene-3β,26-diol, the C-24 epimers of cycloart-25-ene-3β,24,27-triol, the C-24 epimers of cycloartane-3β,24,25-triol and 3-ketodammar-24E-ene-20S,26-diol together with the known compounds cycloartenol, α-amyrin, β-amyrin, sitosterol 3β-hydroxycycloart-25-en-26-al, dammarenediol II, the C-24 epimers of cycloart-25-ene-3β,24-diol, 24-methylenecycloartane-3β,26-diol, ψ-taraxastane-3β,20-diol and ocotillol II have been isolated. The acidic fraction of the same extract, on esterification with diazomethane followed by chromatography, yielded methyl mangiferonate, methyl isomangiferolate, methyl mangiferolate and the diazomethane adduct of methyl mangiferolate. The structures were elucidated by spectroscopic and chemical methods. 相似文献
48.
Polyphosphoinositide activation of cholesterol side chain cleavage with purified cytochrome P-450scc
Highly purified beef adrenal cytochrome P-450 specific for cholesterol side chain cleavage (P-450-scc) has been reconstituted with sonicated vesicles containing cholesterol and either dimyristoyl phosphatidylcholine (DMPC) or dioleoyl phosphatidylcholine (DOPC). When cholesterol was present in DMPC vesicles at 1:15 molar ratio, cardiolipin and L-alpha-phosphatidylinositol 4-monophosphate (DPI) increased side chain cleavage by at least 5-fold (0.7 min-1-3.5 min-1). In DOPC vesicles, a smaller increase was observed (2.8 min-1-5.0 min-1). Activator phospholipids increased the rate of transference of cholesterol both to and from the cytochrome when, respectively, cholesterol-free P-450scc and cholesterol-P-450scc complex are combined with either DMPC or DOPC vesicles. Transfer of cholesterol to and from cytochrome P-450 occurred with similar first order rate constants and was also independent of the concentrations of cholesterol vesicles and P-450. It is suggested that transfer in both directions is limited by the rate of insertion of P-450scc into the membrane. Phospholipid stimulatory effects for both cholesterol transfer and for activation of side chain cleavage occurred with the same ranking, even though cholesterol transfer, following reconstitution, was 5-10 times slower than the turnover of side chain cleavage. DPI increased Vmax for side chain cleavage in both DMPC and DOPC vesicles to the same rate (12 min-1) without effect on the Km for cholesterol, while cardiolipin both produced a similar increase in Vmax and decreased Km (cholesterol). This activation by DPI is attributed to more favorable incorporation of P-450scc in these membranes and is consistent with previously reported effects of acidic phospholipids on other mitochondrial proteins. 相似文献
49.
50.