Acid phosphatase in the lysosomal and microsomal fractions of human prostatic epithelium

Polyacrylamide gel electrophoresis of acid phosphatase from prostatic tissue reveals one more band than seminal plasma. It was attempted to ascertain which subcellular fraction was responsible for that intracellularly localized enzyme. Prostatic epithelium from patients with prostatic hyperplasia was homogenized, and a lysosomal and microsomal fraction were prepared by differential centrifugation. These two fractions were further centrifuged on an isopycnic Percoll gradient. The intracellularly localized form of acid phosphatase was associated with the lysosomal as well as with the microsomal fraction. In a fused rocket electrophoresis experiment these acid phosphatases cross-reacted with antiserum from seminal plasma. After neuraminidase treatment of the acid phosphatase of lysosomal and microsomal origin, only one activity band was found in polyacrylamide gels. It is concluded that only one acid phosphatase protein exists in prostatic epithelium; differences in electrophoretic mobility are caused mainly by different amounts of sialic acid residues, coupled to the same protein backbone.     

Keratinocyte-derived Cytokines and UVB-Induced Immunosuppression

Ultraviolet radiation (UVB) in sunlight is known to have multiple effects on the immune system. Evidence suggests that UVB-induced immunosuppression is mediated in part by immunosuppressive and immunoregulatory cytokines. Our studies have utilized gene-targeted mutant mice to determine key molecular requirements essential for the development of UVB-induced immunosuppression. Preliminary results from our laboratory suggest that TNF-α plays a regulatory role in contact hypersensitivity, but is not a crucial factor for UVB-induced immunosuppression, and that multiple factors are involved in the induction of UVB mediated immunosuppression.     

Inhibition of ligand binding to g protein-coupled receptors by arachidonic acid

Arachidonic acid (AA), released in response to muscarinic acetylcholine receptor (mAChR) stimulation, previously has been reported to function as a reversible feedback inhibitor of the mAChR. To determine if the effects of AA on binding to the mAChR are subtype specific and whether AA inhibits ligand binding to other G protein-coupled receptors (GPCRs), the effects of AA on ligand binding to the mAChR subtypes (M₁, M₂, M₃, M₄, and M₅) and to the μ-opioid receptor, β₂-adrenergic receptor (β₂-AR), 5-hydroxytryptamine receptor (5-HTR), and nicotinic receptors were examined. AA was found to inhibit ligand binding to all mAChR subtypes, to the β₂-AR, the 5-HTR, and to the μ-opioid receptor. However, AA does not inhibit ligand binding to the nicotinic receptor, even at high concentrations of AA. Thus, AA inhibits several types of GPCRs, with 50% inhibition occurring at 3–25 μM, whereas the nicotinic receptor, a non-GPCR, remains unaffected. Further research is needed to determine the mechanism by which AA inhibits GPCR function.     

透明质酸在脑出血和腔隙性脑梗塞中病理作用的探讨

本文对５７例急性脑出血和脑腔梗患者及３５例对照组血清透明质酸（ＨＡ）含量进行了测定，并与相应的临床指标（病程、血压及神经功能缺损评分等）、血液生化指标（血糖、血脂、纤维蛋白原及血液流变学等）和影像学指标进行了相关分析。结果表明：脑出血和脑腔梗组的ＨＡ含量明显高于对照组，腔梗组明显高于出血组（Ｐ＜０．０１）。脑出血组ＨＡ含量与纤维蛋白原含量呈明显负相关，与其它指标无相关性。而脑腔梗组ＨＡ含量与纤维蛋白原及其它指标均无相关性。     

Urinary mercapturic acid diastereoisomers in rats subchronically exposed to styrene and ethanol

 Styrene is stereoselectively oxidized by cytochrome P450 to its reactive metabolite, styrene oxide. The (R)- and (S)-enantiomers of styrene oxide can be conjugated with glutathione (GSH) to both (R)- and (S)-diastereoisomers of the specific mercapturic acids, N-acetyl-S-(1-phenyl-2-hydroxyethyl)-L-cysteine (M1) and N-acetyl-S-(2-phenyl-2-hydroxyethyl)-L-cysteine (M2). Several investigations have indicated different toxic potential of the (R)- and (S)-configurations of styrene oxide and its GSH- and N-acetyl-conjugates. In this study the mercapturic acid diastereoisomers were measured in the urine of rats exposed to styrene in combination with ethanol, a good inducer of styrene metabolism. Male Sprague-Dawley rats were given an isocaloric liquid diet containing ethanol (5% w/v) for 3 weeks. Starting from the 2nd week, the animals were also exposed to styrene vapours (300 ppm, 6 h/day, 5 days/week) in a dynamic exposure chamber. Both the (R)- and (S)-diastereoisomers of the M1 and M2 as well as the conventional biomarkers, mandelic acid (MA) and phenylglyoxylic acid (PGA) were measured in urinary samples. Approximately 30 and 25% reduction of the levels of brain non-protein sulfhydryls (NPS) was observed in the animals given styrene and ethanol, respectively, while the combined ethanol and styrene treatment resulted in a 60% decrease. Ethanol consumption also resulted in higher urinary levels of the M1-R, M1-S and M2 metabolites associated with increased M1-R/S ratio and higher urinary MA excretion compared to animals treated with styrene. These results suggest that the urinary mercapturic acid diastereoisomers may be used as a noninvasive tool to examine stereoselective patterns of styrene metabolism in vivo, as well as their alterations caused by ethanol. These compound-specific mercapturic acids may also be valuable indicators of styrene-induced disorders of GSH homeostasis in nonaccessible organs. Received: 19 December 1995/Accepted: 10 May 1996     

急性心肌梗塞患者血清唾液酸含量测定

本文测定了５０例正常人，３２例急性心肌梗塞，５４例冠心病无梗塞者血清ＳＡ水平，结果表明，急性心肌梗塞组血清ＳＡ水平与冠心病无梗塞组及正常人相比，具显著性差异，可能与心肌梗塞造成心肌细胞受损所致使细胞表面成份释放入血有关，所以血清ＳＡ测定可提供一新的心肌梗塞诊断依据。     

Growth and differentiation of adult rat hepatocytes regulated by the interaction between parenchymal and non-parenchymal liver cells

We have devised a medium which supports the continuous growth of hepatocytes without losing their replicative potential and differentiation capacity for a longer period. The medium HCGM, contains four key substances in addition to foetal bovine serum. They are epidermal growth factor, nicotinamide, ascorbic acid 2-phosphate and dimethylsulphoxide. When a non-parenchymal cell fraction containing small hepatocytes and non-parenchymal cells was cultured in HCGM, small hepatocytes grew clonally and differentiated into cells expressing either mature hepatocyte marker proteins or biliary cell marker proteins. Thus, for the first time, we showed the presence of a small compartment of bipotent and highly replicative clonogenic hepatocytes in the rat adult liver. HCGM also supported the growth of stellate cells (Ito cells) which were in the original preparation, suggesting the important role of stellate cells for the successful cultivation of hepatocytes. Together, these results suggest that a microenvironment is produced as a result of cooperative interactions between hepatocytes and stellate cells: one which stimulates the growth and differentiation of clonogenic hepatocytes.     

Synthesis and Antitumour Activity of New Derivatives of Flavone-8-acetic Acid (FAA). Part 1: 6-Methyl Derivatives

A range of 17 derivatives of flavone-8-acetic acid (FAA) with a 6-methyl substituent have been prepared and their anti-tumour activity evaluated in vitro against a panel of human and murine tumour cell lines and in vivo against MAC 15A. While many of the compounds show activity comparable to FAA in vitro, this essentially disappears in vivo, possibly due to degradation before the compounds can reach the tumour site.