良性前列腺增生组织中一氧化氮合酶活性的变化

为探讨一氧化氮（ＮＯ）与良性前列腺增生（ＢＰＨ）发病的关系，应用双波长分光光度法测定１５例正常前列腺及２５例ＢＰＨ组织中一氧化氮合酶（ＮＯＳ）活性，并比较不同年龄组的正常前列腺及ＢＰＨ组织中ＮＯＳ活性水平。结果：ＢＰＨ组织中ＮＯＳ活性（９６．７７±２８．０２ｐｍｏｌ．ｍｇ－１．ｍｉｎ－１）明显低于正常前列腺者（２９０．９９±１３０．６８ｐｍｏｌ．ｍｇ－１．ｍｉｎ－１），Ｐ＜０．００１。不同年龄组的正常前列腺组织中ＮＯＳ活性水平与年龄无相关关系。而在５０岁、６０岁和≥７０岁三个年龄组之间的ＢＰＨ组织中ＮＯＳ活性水平有显著性差异，Ｐ＜０．０１，ＢＰＨ组织中ＮＯＳ活性水平随年龄增大呈下降趋势。结果提示前列腺组织中ＮＯＳ活性水平与ＢＰＨ有相关关系，ＮＯＳ活性降低可能是ＢＰＨ的年龄依赖性发病原因之一。     

Biosynthetic and regulatory role of lys9 mutants of Saccharomyces cerevisiae

Summary Derepression of lysine biosynthetic enzymes of Saccharomyces cerevisiae was investigated in lys9 auxotrophs which lack saccharopine reductase activity. Five enzymes (homocitrate synthase, homoisocitrate dehydrogenase, -aminoadipate aminotransferase, -aminoadipate reductase and saccharopine dehydrogenase) were constitutively derepressed in all lys9 mutants with up to eight-fold higher enzyme levels than in isogenic wild-type cells. Levels of these enzymes in lys2, lys14, and lys15 S mutants were the same or lower than those in wild-type cells. The regulatory property of lys9 mutants exhibited recessiveness to the wild-type gene in heterozygous diploids. Unlike the mating type effect, homozygous diploids resulting from crosses between lys9 auxotrophs exhibited even higher levels of derepressed enzymes than the haploid mutants. Addition of a higher concentration of lysine to the growth medium resulted in reduction of enzyme levels although they were still derepressed. These results suggest that lys9 mutants represent a lesion for the saccharopine reductase and may represent a repressor mutation which in the wild-type cells simultaneously represses unlinked structural genes that encode for five of the lysine biosynthetic enzymes.     

Metabolic and phenotypic characteristics of human skeletal muscle fibers as predictors of glycogen utilization during electrical stimulation

Characteristics of skeletal muscle such as fiber type composition and activities of key metabolic enzymes have been purported to affect glycogen utilization. However, the relative importance individual factors may have in predicting glycogen utilization of individual muscle fibers has not been addressed. Thus, we sought to determine the relative importance that metabolic characteristics and phenotypic expression of individual fibers have in predicting fiber specific glycogen utilization during neuromuscular electrical stimulation (NMES) exercise. Biopsies were taken from the m, vastus lateralis (VL) of eight recreationally active males before and immediately after 30 min of non-fatiguing NMES and analyzed for type (I, IIa and IIx), succinate dehydrogenase activity (SDH), glycerol-phosphate dehydrogenase activity (GPDH), quantitative-actomyosin adenosine triphosphatase activity (qATPase), and glycogen content. Our results demonstrate that a ratio of enzyme activities representing pathways for energy supply and energy demand (SDH: qATPase) accounted for more of the variance in glycogen utilization (y=0.2091 e^−0.0329x , R ²=0.622, P≤ 0.0001) than SDH (R ²=0.321) or qATPase (R ²=0.365) alone. Fiber phenotype was also a significant predictor of glycogen utilization, but to a lesser extent than the other variables studied (R ²=0.201). A ratio of the activities of enzymes representing pathways of energy supply and energy demand, represented by SDH:qATPase, is a better predictor of glycogen utilization than either of its components independently while fiber phenotype, although a statistically significant predictor of glycogen utilization, may not be the most appropriate determinate of the functional characteristics of an individual fiber.     

睫状神经营养因子对损伤脊髓神经元酶学的影响

目的：研究脊髓损伤后脊髓神经元的酶学变化,并探索睫状神经营养因子（CNTF）对脊髓神经元的保护作用。方法：用改良Allen打击法致SD大鼠T8脊髓损伤,分别于术术前术后第3、7、14天测定脊髓组织内乙酰胆碱酯酶（AChE)和酸性磷酸酶（ACP）的含量。结果：AChE于手术持续下降,ACP在术后3天开始上升,第7天升至最高,以后逐渐下降,经CNTF治疗后上述峡谷种酶变化的幅度较小,且整个过程比较平衡,结论：CNTF对脊髓损伤的神经元具有一定的保护作用。     

The physiological and pharmacological roles of cytochrome P450 isoenzymes

The cytochrome P450 isoenzymes are a superfamily of haemoprotein enzymes that catalyse the metabolism of a large number of endogenous and exogenous compounds. Recently, the cytochrome isoenzymes have been shown to be important in the synthesis of steroid hormones and bile acids, the arachidonic acid cascade and in central nervous function. These enzymes are a major determinant of the pharmacokinetic behaviour of numerous drugs. Furthermore, alterations in cytochrome P450 activity have been implicated in some diseases.     

Glutaric aciduria type I

Summary Serial CT findings in an infant with glutaric aciduria type I (GA-I) are reported. The major CT features were dilatation of the insular cisterns, regression of the temporal lobes, with bat wings dilatation of the Sylvian fissures and hypodensity of the lenticular nuclei. CT changes preceded the onset of symptoms by 3 months. An improvement in the temporal lobe atrophy was seen after a period of treatment, coinciding with marked clinical improvement. A peculiar feature was the presence of external hydrocephalus, which diverted the attention from manifestations of the primary disease and thus consitituted a diagnostic pitfall. The delineation and recognition of the characteristic radiologic manifestations of GA-I are essential for allowing an adequate radiologist/clinican interaction in diagnosing this inborn error of metabolism.     

Effects of L-ascorbic acid supplementation on dieldrin toxicity in rats

Chronic dieldrin administration to rats (5 mg/kg/day) produced pathological changes in liver and kidney tissues. Dieldrin treated rats showed high levels of liver ascorbic acid and increased activities of inorganic pyrophosphatase in brain and glucose-6-phosphatase in liver. The activities of Mg²⁺-ATPase in liver and acetylcholinesterase in brain were decreased under toxic doses of dieldrin. L-Ascorbic acid supplements in treated animals could partially prevent the pathological alterations, as observed histologically in liver and kidney tissues. Administration of this vitamin could also prevent alterations in some enzyme activities produced by toxic dieldrin doses.     

Defining the rate of nutritional and metabolic derangements after pancreatic resection

Background and aimsPancreatic resection is associated with pancreatic exocrine insufficiency (PEI) leading to nutritional consequences. The Pancreatic Nutrition Clinic was established to diagnose and manage PEI through standardised nutritional assessment. In this prospective observational study, we aimed to define the rate of PEI, diabetes mellitus and nutritional abnormalities in patients who underwent pancreatic resection.MethodsAll Pancreatic Nutrition Clinic patients were included for analysis. Clinical data were prospectively obtained at initial assessment. Biochemical data included micronutrient levels, faecal elastase-1 and haemoglobin A1c. Bone mineral density and nutritional assessment were undertaken.ResultsNinety-eight patients were included. Fifty-nine per cent (58/98) had undergone a pancreatoduodenectomy. Ninety-three patients had a faecal elastase-1 result, 65% (60/93) of which had a faecal elastase-1 less than 200 μg/g of faeces. Seventy-five patients (76%) of the total population required PERT, and thirty-nine (40%) were classified as malnourished using the patient-generated subjective global assessment tool. Seventy-two per cent (70/97) had a biochemical deficiency of one or more micronutrients. Thirty-eight people (39%) had diabetes mellitus. Of the seventy-eight patients with a bone mineral density scan available for analysis, 29% (23/78) had osteoporosis and 49% (38/78) osteopenia.ConclusionsPancreatic exocrine insufficiency, micronutrient deficiency, bone disease, diabetes mellitus and malnutrition are highly prevalent in patients who have undergone pancreatic resection.     

2型糖尿病患者高密度脂蛋白亚型分子组分的变化

目的 研究2型糖尿病患者高密度脂蛋白亚型分子构成成分含量、代谢关键酶活性变化及与血糖等指标的相关关系.方法 26例新发2型糖尿病患者与25例健康对照者留取血浆检测血糖、胰岛素和血脂谱.以改良一步沉淀法分离高密度脂蛋白3并检测其组分含量,并计算高密度脂蛋白2的主要组分含量.以荧光酶法测定胆固醇酯转运蛋白和磷脂转运蛋白活性.结果 (1)2型糖尿病组血高密度脂蛋白胆固醇与对照组无显著差异(P=0.579).(2)2型糖尿病组与对照组的胆固醇酯转运蛋白和磷脂转运蛋白活性均无明显差异.(3)2型糖尿病组高密度脂蛋白3以下组分含量较对照组明显减少(均P＜0.01):胆固醇为0.60±0.17 mmol/L比0.75±0.22mmol/L,磷脂为1.14±0.19 mmol/L比1.29±0.22 mmol/L,游离胆固醇为0.021±0.012 mmol/L比0.033±0.012mmoL/L,胆固醇酯为0.97±0.28 mmol/L比1.19±0.36 mmol/L.其中游离胆固醇和胆固醇酯含量与餐后血糖、糖化血红蛋白、胰岛素抵抗指数呈显著负相关(P＜0.05).(4)2型糖尿病组高密度脂蛋白2的载脂蛋白AI含量较对照组显著降低(604.8±233.3 mg/L比755.4±198.0 mg/L,P＜0.05),并与胰岛素抵抗指数、餐后血糖、血甘油三酯呈显著负相关(P＜0.05).结论 2型糖尿病患者高密度脂蛋白3和高密度脂蛋白2颗粒主要组分含量明显减少,并与血糖水平及胰岛素抵抗程度相关.     

Disturbance of antioxidant capacity produced by beauvericin in CHO-K1 cells

Glutathione (GSH) levels, glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione-S-transferase (GST) as antioxidant defense system were evaluated in CHO-K1 cells after beauvericin (BEA) exposure. The effect of N-acetyl-cysteine (NAC) pre-treatment was assessed. GSH levels significantly decrease 18% and 29% after 5 μM of BEA in fresh medium and NAC pre-treatment, respectively compared to their controls. The GPx activity increased significantly from 35% to 66% in fresh medium and 20% in NAC pre-treatment. GR activity decreased after 5 μM of BEA up to 43% and 53% in fresh medium and NAC pre-treatment, respectively. The GST activity increased in fresh medium (from 61% to 89%) and decreased (from 22% to 35%) after NAC pre-treatment. Comparing BEA exposure in fresh medium and NAC pre-treatment, GSH levels, GPx activity and GST activity increased 716%, 458% and 206%, respectively respect to fresh medium; conversely no changes were observed in GR activity. In addition, NAC is an effective scavenger of BEA. GSH and related enzymes play an antioxidant role in the defense system of CHO-K1 cells exposed to BEA.