Preventive effect of a chicken extract on the development of hypertension in stroke-prone spontaneously hypertensive rats

The antihypertensive effect of Brand's Essence of Chicken (BEC), a popular chicken extract used as a traditional health food, was examined with stroke-prone spontaneously hypertensive rats (SHRSPs). The animals were maintained from 6 to 25 weeks of age on drinking water with or without BEC. The BEC-fed group showed a significant reduction in the development of hypertension when compared with the control animals. The levels of blood urea nitrogen and plasma creatinine in the BEC-fed group were significantly lower than those in the control group, suggesting that the renal glomerular function had been improved by the daily administration of BEC. It thus seems likely that BEC would be useful as a prophylactic treatment against the development of hypertension and renal injury.     

Changes in lignin content of leaf litters during mulching

Alkaline nitrobenzene oxidation, ozonation and methoxyl content determinations were applied to decomposing leaf litter of Ginkgo biloba L., Cinnamomum camphora sieb., Zelkova serrata Makino and Firmiana simplex W. F. Wight, respectively, during mulching to investigate the properties and estimate changes in lignin composition and content. Since the Klason lignin residue originated from components highly resistant to degradation by acid, the methoxyl content of Klason residue was used to estimate the lignin content of leaf litter. Quantitative analysis of presumed lignin-derived fragments, by use of alkaline nitrobenzene oxidation and ozonation methods, suggested that the estimated lignin content approximates that of the real lignin content of leaves, which is greatly overestimated by the Klason procedure. The estimated lignin contents ranged from 3.9 to 10.0% while the Klason lignan residue varied from 37.1 to 46.7% in un-mulched leaf litter. The absolute amounts of the measured lignin somewhat decreased during mulching, while the structure of lignin remaining in leaf litters after mulching was considered not to be very different from its original structure.     

Superoxide and hydrogen peroxide production by Drosophila mitochondria

Drosophila melanogaster is a key model organism for genetic investigation of the role of free radicals in aging, but biochemical understanding is lacking. Superoxide production by Drosophila mitochondria was measured fluorometrically as hydrogen peroxide, using its dependence on substrates, inhibitors, and added superoxide dismutase to determine sites of production and their topology. Glycerol 3-phosphate dehydrogenase and center o of complex III in the presence of antimycin had the greatest maximum capacities to generate superoxide on the cytosolic side of the inner membrane. Complex I had significant capacity on the matrix side. Center i of complex III, cytochrome c, and complex IV produced no superoxide. Native superoxide generation by isolated mitochondria was also measured without added inhibitors. There was a high rate of superoxide production with sn-glycerol 3-phosphate as substrate; two-thirds mostly from glycerol 3-phosphate dehydrogenase on the cytosolic side and one-third on the matrix side from complex I following reverse electron transport. There was little superoxide production from any site with NADH-linked substrate. Superoxide production by complex I following reverse electron flow from glycerol 3-phosphate was particularly sensitive to membrane potential, decreasing 70% when potential decreased 10 mV, showing that mild uncoupling lowers superoxide production in the matrix very effectively.     

A potential mechanism for the impairment of nitric oxide formation caused by prolonged oral exposure to arsenate in rabbits

We have recently found evidence for impairment of nitric oxide (NO) formation and induction of oxidative stress in residents of an endemic area of chronic arsenic poisoning in Inner Mongolia, China. To investigate the underlying mechanisms responsible for these phenomena, a subchronic animal experiment was conducted using male New Zealand White rabbits. After 18 weeks of continuous exposure of rabbits to 5 mg/l of arsenate in drinking water, a significant decrease in systemic NO production occurred, as shown by significantly reduced plasma NO metabolites levels (76% of control) and a tendency towards decreased serum cGMP levels (81.4% of control). On the other hand, increased oxidative stress, as shown by significantly increased urinary hydrogen peroxide (H(2)O(2)) (120% of control), was observed in arsenate-exposed rabbits. In additional experiments measuring aortic tension, the addition of either the calcium ionophore A23187 or acethylcholine (ACh) induced a transient vasoconstriction of aortic rings prepared from arsenate-exposed rabbits, but not in those prepared from control animals. This calcium-dependent contractility action observed in aorta rings from arsenate-exposed rabbits was markedly attenuated by the superoxide (O2(.-)) scavenging enzyme Cu, Zn-SOD, as well as diphenyleneiodonium (DPI) or N(G)-nitro-L-arginine methyl ester (L-NAME), which are inhibitors for nitric oxide synthase (NOS). However, the cyclooxygenase inhibitor indomethacin or the xanthine oxidase blocker allopurinol had no effect on this vasoconstriction. These results suggest that arsenate-mediated reduction of systemic NO may be associated with the enzymatic uncoupling reaction of NOS with a subsequent enhancement of reactive oxygen species such as O2(.-), an endothelium-derived vasoconstricting factor. Furthermore, hepatic levels of (6R)-5,6,7,8-tetrahydro-L-biopterin (BH(4)), a cofactor for NOS, were markedly reduced in arsenate-exposed rabbits to 62% of control, while no significant change occurred in cardiac L-arginine levels. These results suggest that prolonged exposure of rabbits to oral arsenate may impair the bioavailability of BH(4) in endothelial cells and, as a consequence, disrupt the balance between NO and O2(.-) produced from endothelial NOS, such that enhanced free radicals are produced at the expense of NO.     

Linoleic acid 10-hydroperoxide as an intermediate during formation of 1-octen-3-ol from linoleic acid in Lentinus decadetes

In order to confirm the biosynthetic pathway to 1-octen-3-ol from linoleic acid, a crude enzyme solution was prepared from the edible mushroom, Lentinus decadetes. When the reaction was performed in the presence of glutathione peroxidase, which can reduce organic hydroperoxide to the corresponding hydroxide, the amount of 1-octen-3-ol formed from linoleic acid was decreased. At the same time, an accumulation of linoleic acid 10-hydroxide could be detected. The 10-hydroperoxide therefore seems to be an intermediate on the biosynthetic pathway.     

Involvement of protein tyrosine phosphorylation in the effect of green tea polyphenols on Ehrlich ascites tumor cells in vitro

Green tea extract and its polyphenolic components have been found to possess anticarcinogenic, antimutagenic, antihypertensive and antihepatotoxic effects, and several mechanisms have been proposed for these effects. In this study, the effects of five tea polyphenols, (−)-epigallocatechin-3-gallate (EGCG), (−)-epigallocatechin (EGC), (−) epicatechin-3-gallate (ECG), (−) epicatechin (EC) and (+)-catechin (C), were examined on the viability of Ehrlich ascites tumor cells in vitro and a possible relationship with tyrosine phosphorylation was determined. Proteins extracted from the cells treated with the tea polyphenols were separated by SDS-PAGE, and tyrosine-phosphorylated proteins were detected by immunoblotting with anti-phosphotyrosine antibody and the extent of phosphorylation determined. EGC (100 μM) caused a significant decrease in cell viability to 4.1±0.2% of the control value, and this correlated with a stimulation of protein tyrosine kinase (PTK) activity. EGCG (100 μM) also caused a slight decrease in cell viability (70% of the control value) but this and the other polyphenols, which had no effect on cell viability likewise, had no effect on tyrosine phosphorylation. Tyrosine phosphorylations of 42 and 45 kDa proteins were also observed for EGC. Further evaluation of the effect of EGC showed that the activity of ornithine decarboxylase (ODC), a key enzyme in polyamine biosynthesis in cells, decreased significantly as well. A significant correlation has therefore been observed between a cellular event, namely, a reduction in the viability of Ehrlich ascites tumor cells and an association with a tyrosine phosphorylation of 42 and 45 kDa proteins by the polyphenol EGC.     

Embryonic Medaka Model of Microglia in the Developing CNS Allowing In Vivo Analysis of Their Spatiotemporal Recruitment in Response to Irradiation

Radiation therapy (RT) is pivotal in the treatment of many central nervous system (CNS) pathologies; however, exposure to RT in children is associated with a higher risk of secondary CNS tumors. Although recent research interest has focused on the reparative and therapeutic role of microglia, their recruitment following RT has not been elucidated, especially in the developing CNS. Here, we investigated the spatiotemporal dynamics of microglia during tissue repair in the irradiated embryonic medaka brain by whole-mount in situ hybridization using a probe for Apolipoprotein E (ApoE), a marker for activated microglia in teleosts. Three-dimensional imaging of the distribution of ApoE-expressing microglia in the irradiated embryonic brain clearly showed that ApoE-expressing microglia were abundant only in the late phase of phagocytosis during tissue repair induced by irradiation, while few microglia expressed ApoE in the initial phase of phagocytosis. This strongly suggests that ApoE has a significant function in the late phase of phagocytosis by microglia in the medaka brain. In addition, the distribution of microglia in p53-deficient embryos at the late phase of phagocytosis was almost the same as in wild-type embryos, despite the low numbers of irradiation-induced apoptotic neurons, suggesting that constant numbers of activated microglia were recruited at the late phase of phagocytosis irrespective of the extent of neuronal injury. This medaka model of microglia demonstrated specific recruitment after irradiation in the developing CNS and could provide a useful potential therapeutic strategy to counteract the detrimental effects of RT.