Neuroprotective effect of CPDT on THA-induced cortical motor neuron death in an organotypic culture model.

Brain stroke, trauma, and motor neuron disease each can result in cortical motoneuron (CMN) death or impairment. Glutamate excitotoxicity induces motor neuron damage in both acute motor neuron loss and chronic motor neuron degeneration. It is necessary to find effective strategies to protect CMNs from excitotoxicity in a variety of pathological conditions. 5,6-Dihydrocyclopenta-1,2-dithiole-3-thione (CPDT) is one of the phase II enzyme inducers. In our previous report, CPDT was shown to have neuroprotective effects on the spinal cord, by activating the Nrf2/ARE pathway to increase antioxidative capacity. In this study, in order to figure out whether CPDT can prevent CMN's from THA-induced death, we set up an organotypic brain slice culture system. Threo-hydroxyaspartate (THA), a glutamate transport inhibitor, was added to the culture medium to induce CMN death by glutamate excitotoxicity. Brain slices were pretreated with CPDT for 48h, then treated with CPDT and THA simultaneously for 3 weeks. We found that pretreatment with CPDT significantly increased CMN survival. Glutamate concentration in the culture medium was significantly greater following THA treatment, whereas no significant decrease was found in the CPDT pretreatment group. However, both Nrf2 and HO-1 protein expression was significantly elevated in the CPDT pretreatment group, and Nrf2 protein translocated to the nucleus after CPDT stimulation. These findings suggest that CPDT can protect CMNs from THA-induced motor neuron death by activating the Nrf2 pathway and increasing HO-1 protein expression. Therefore, increasing antioxidative defense capacity should benefit to upper motor neuron survival following a glutamate excitotoxicity insult.

Mitochondrial HMG-CoA synthase partially contributes to antioxidant protection in the kidney of stroke-prone spontaneously hypertensive rats.

OBJECTIVE: Increased oxidative stress plays an important role in cardiovascular diseases including hypertension and stroke. Evidence has indicated that ketone bodies could exert antioxidative effects. We explored the role of renal mitochondrial 3-hydroxy-3-methylglutaryl-coenzyme A synthase (HMGCS2) expression, a key control site of ketogenesis, in stroke-prone spontaneously hypertensive rats (SHRSPs) and their ancestral hypertensive but stroke-resistant spontaneously hypertensive rats (SHRs). METHODS: Two groups of SHRSPs were fed a standard chow or standard chow supplemented with clofibrate (an agonist of HMGCS2 promoter), respectively, and SHRs fed with a standard chow were used as controls. The renal levels of HMGCS2, Akt, and phosphorylated protein kinase B (Akt) were measured by western blotting. Malondialdehyde, catalase, superoxide dismutase, and glutathione peroxidase were detected by assay kits. RESULTS: Compared with SHRs, lower HMGCS2 protein expression, enhanced phosphorylated Akt signal, higher malondialdehyde levels, and higher catalase activity were observed in kidney tissues in SHRSPs (P < 0.05). No differences in superoxide dismutase and glutathione peroxidase activities were observed between SHRSPs and SHRs. Clofibrate treatment significantly upregulated renal HMGCS2 expressions, inhibited phosphorylation of Akt, and decreased malondialdehyde levels and catalase activities in SHRSP kidney tissues (P < 0.05). CONCLUSION: These results demonstrated the difference in HMGCS2 expression and oxidative stress in kidney tissues between SHRSPs and their SHR controls. The enhanced oxidative stress was partly due to the lower HMGCS2 expression regulated possibly by the Akt signaling pathway.

Green tea polyphenols inhibit plasminogen activator inhibitor-1 expression and secretion in endothelial cells.

Compelling epidemiological evidence suggests that the consumption of green tea is associated with beneficial effects in prevention of cardiovascular diseases. Plasminogen activator inhibitor-1 (PAI-1) is known to play a pivotal role in cardiovascular diseases including arteriosclerosis and hypertension. Increased PAI-1 was found in atherosclerotic lesions, and high PAI-1 plasma levels were associated with coronary heart disease. To determine the effect and molecular mechanism of green tea polyphenols (GTPs) on the regulation of PAI-1 expression in endothelial cells, bovine aortic endothelial cells were incubated with GTPs, and PAI-1 expressions were measured by western blot and enzyme-linked immunosorbent assay, respectively. GTPs significantly reduced PAI-1 expression and secretion in a time-dependent and dose-dependent manner. Inhibition of phosphatidylinositol 3-kinase (PI3K) with wortmannin markedly reversed GTPs repression of PAI-1 expression. In addition, the GTP-induced inhibitory effect was associated with an increased of activation of the protein kinase Akt. These results suggest that GTPs inhibit PAI-1 expression and its release from endothelial cells through the PI3K/Akt pathway, which may contribute to cardiovascular protection.

Conversion of paper sludge to ethanol in a semicontinuous solids-fed reactor.

Conversion of paper sludge to ethanol was investigated with the objective of operating under conditions approaching those expected of an industrial process. Major components of the bleached Kraft sludge studied were glucan (62 wt.%, dry basis), xylan (11.5%), and minerals (17%). Complete recovery of glucose during compositional analysis required two acid hydrolysis treatments rather than one. To avoid the difficulty of mixing unreacted paper sludge, a semicontinuous solids-fed laboratory bioreactor system was developed. The system featured feeding at 12-h intervals, a residence time of 4 days, and cellulase loading of 15 to 20 FPU/g cellulose. Sludge was converted to ethanol using simultaneous saccharification and fermentation (SSF) featuring a beta-glucosidase-supplemented commercial cellulase preparation and glucose fermentation by Saccharomyces cerevisiea. SSF was carried out for a period of 4 months in a first-generation system, resulting in an average ethanol concentration of 35 g/L. However, steady state was not achieved and operational difficulties were encountered. These difficulties were avoided in a retrofitted design that was operated for two 1-month runs, achieving steady state with good material balance closure. Run 1 with the retrofitted reactor produced 50 g/L ethanol at a cellulose conversion of 74%. Run 2 produced 42 g/L ethanol at a conversion of 92%. For run 2, the ethanol yield was 0.466 g ethanol/g glucose equivalent fermented and >94% of the xylan fed to the reactor was solubilized to a mixture of xylan oligomers and xylose.