Inhibition of L-Arginine Metabolizing Enzymes by L-Arginine-Derived Advanced Glycation End Products

Nω-Carboxymethyl-arginine (CMA), Nω-carboxyethyl-arginine (CEA) and Nδ-(5-hydro-5-methyl-4-imidazolon-2-yl)-ornithine (MG-H1) have been identified as L-arginine-derived advanced glycation end products (AGEs) formed by non-enzymatic reactions between reducing sugars such as glucose and amino groups in proteins. These AGEs are structurally analogous to endogenous inhibitors of nitric oxide synthases (NOS) including NG-monomethyl-L-arginine (L-NMMA) and asymmetric NG,NG-dimethyl-L-arginine (ADMA). Increased plasma levels of these NOS inhibitors, and thus impaired generation of NO in vivo has been associated with the pathogenesis of vascular complications such as kidney failure and atherosclerosis. For these reasons we examined whether L-arginine-derived AGEs inhibit the activities of three L-arginine metabolizing enzymes including three isoforms of NOS (endothelium, neuronal and inducible NOS), dimethylarginine dimethylaminohydrolase (DDAH) that catalyzes the hydrolytic degradation of L-NMMA and ADMA to L-citrulline, and arginase that modulates intracellular L-arginine bioavailability. We found that AGEs inhibited the in vitro activities of endothelium type NOS weakly (IC50 values of CMA, CEA and MG-H1 were 830, 3870 and 1280 µM, respectively) and were also potential endogenous inhibitors for arginase (IC50 values of CMA and CML were 1470 and 1060 µM), but were poor inhibitors for DDAH. These results suggest that the tested L-arginine- and L-lysine-derived AGEs appear not to impair NO biosynthesis directly

Lectin-like oxidized low density lipoprotein receptor-1 (LOX-1) serves as an endothelial receptor for advanced glycation end products (AGE)

AbstractAdvanced glycation end products (AGE) are known to serve as ligands for the scavenger receptors such as SR-A, CD36 and SR-BI. In the current study, we examined whether AGE is recognized by lectin-like oxidized low density lipoprotein receptor-1 (LOX-1). Cellular binding experiments revealed that AGE-bovine serum albumin (AGE-BSA) showed the specific binding to CHO cells overexpressing bovine LOX-1 (BLOX-1), which was effectively suppressed by an anti-BLOX-1 antibody. Cultured bovine aortic endothelial cells also showed the specific binding for AGE-BSA, which was suppressed by 67% by the anti-BLOX-1 antibody. Thus, LOX-1 is identified as a novel endothelial receptor for AGE

Age- and sun exposure-dependent differences in 8-hydroxy-2'-deoxyguanosine and Nε-(carboxymethyl)lysine in human epidermis

Aging and exposure to sunlight are two major factors in the deterioration of skin function. In this study, thirty-six fixed human skin samples from sun-exposed and unexposed areas from young and old individuals were used to evaluate the localization of oxidative stress according to levels and distribution of 8-hydroxy-2'-deoxyguanosine and Nε-(carboxymethyl)lysine in samples using immunohistochemistry. In the epidermis of the young, negligible amounts of 8-hydroxy-2'-deoxyguanosine and Nε-(carboxymethyl)lysine were detected in unexposed areas, whereas nuclear 8-hydroxy-2'-deoxyguanosine and cytoplasmic Nε-(carboxymethyl)lysine were increased in the lower epidermis in sun-exposed areas. In contrast, the aged presented prominent nuclear 8-hydroxy-2'-deoxyguanosine and nuclear Nε-(carboxymethyl)lysine in the epidermis of unexposed areas, concomitant with dermal increase in Nε-(carboxymethyl)lysine. However, the immunostaining of 8-hydroxy-2'-deoxyguanosine and Nε-(carboxymethyl)lysine revealed a decrease in the epidermis of sun-exposed areas in the aged. These results suggest an age-dependent difference in the adaptation and protective mechanisms of the epidermis against sunlight-associated oxidative stress, thus necessitating distinct standards for evaluation in each age group. Further investigation is warranted to elucidate underlying molecular mechanisms

Electron identification using the TOPAZ detector at TRISTAN

We present an electron-identification method using the time-projection chamber and the lead-glass calorimeter in the TOPAZ detector system. Using this method we have achieved good electron identification against hadron backgrounds over a wide momentum range in the hadronic events produced by both single-photon exchange and two-photon processes. Pion-rejection factors and electron efficiencies were 163 and 68.4\% for high-$P_T$ electrons and 137 and 42.7\% for low-$P_T$ electrons in the single-photon-exchange process, and 8600 and 36.0\% for the two-photon process, respectively.Comment: 32 pages, latex format (article), 24 figures, submitted for publication

Development of New Functional Feed that Utilizes Yacon (\u3cem\u3eSmallanthus sonchifolius\u3c/em\u3e) and Rush (\u3cem\u3eJuncus effuses\u3c/em\u3e L.) in Japan

Yacon (Smallanthus sonchifolius) is acknowledged as a food as well as a medicinal plant and its cultivation in Ja-pan has recently expanded. Rush (Juncus effuses L.) which is widely distributed in the temperate regions in the north-ern hemisphere, has historically been used as a herbal medicine for nephritis and dermal disorders. However, there is a lot of harvest residue of both plants. This research was conducted to find out the way for the effective use of these residues as functional feed resources

Mallory Bodies in Hepatocytes of Alcoholic Liver Disease and Primary Biliary Cirrhosis Contain Nε-(Carboxymethyl)lysine-Modified Cytokeratin, but not those in Hepatic Carcinoma Cells

Mallory bodies (MBs) are intracytoplasmic bodies seen in hepatocytes of alcoholic liver disease, primary biliary cirrhosis and hepatocellular carcinoma. However, the mechanism of MB formation has not been fully understood. Proteins could be modified to advanced glycation end products (AGEs) after long-term incubation with reducing sugar. AGEs are known to accumulate in several tissues in aging and age-enhanced disorders. To study the possible glycation process in the formation of MBs, hepatocytes of 80 human liver tissues with MBs were subjected to immunohistochemical analyses with five AGEs, two markers for oxidative stress proteins (OSPs) and four stress-response proteins (SRPs). MBs in hepatocytes of primary biliary cirrhosis and alcoholic liver disease were strongly positive for Nε-(carboxymethyl)lysine (CML) and weakly positive for pyrraline. MBs in hepatocellular carcinomas were negative for both CML and pyrraline. No significant immunoreactivity was detected in MBs for other AGEs, such as Nε-(carboxyethyl)lysine, pentosidine, and 3DG-imidazolone, or for OSPs and SRPs. Stainings for cytokeratin, a major protein component of MBs, and CML were co-localized. Furthermore, immunoblot analysis suggested that cytokeratin of MBs was modified to AGE, since a single protein band detected by a monoclonal anti-CML had a molecular weight identical to cytokeratin. The absence of the CML signal in MBs of hepatocellular carcinoma cells could be explained by scarce content of cytokeratin in carcinoma MBs