维生素K3诱导肝癌细胞凋亡及SOD、GSH、MDA的变化

目的:分析在维生素K3诱导肝癌SMMC-7721细胞凋亡的过程中细胞内超氧化物歧化酶(SOD)活性和谷胱甘肽(GSH)、丙二醛(MDA)含量的变化。方法:选取对数生长期的肝癌细胞用不同浓度的维生素K3(2、5、10、20、25μmol/L)以不同的作用时间(12、24、48、72 h)进行诱导,用流式细胞仪检测细胞凋亡率(Annexin V/PI法)变化;化学显色法测定不同浓度维生素K3作用48h后肝癌细胞内SOD活性和GSH、MDA含量的变化。结果:5个维生素K3浓度作用肝癌细胞48 h后早期凋亡率分别是18.75%,25.80%,38.06%,29.92%,27.68%;除2μmol/L组的SOD活性外,5、10、20μmol/L浓度组细胞内的SOD活性和GSH含量随着维生素K3浓度的增加而明显下降,而代谢产物MDA含量均明显增加,呈明显的剂量依赖性;20μmol/L和25μmol/L浓度组之间上述指标的变化无显著性差异。结论:维生素K3作用SMMC-7721细胞48 h后可诱导肝癌细胞发生凋亡,呈明显的剂量浓度依赖性,氧化应激是诱发细胞凋亡的关键步骤。     

H2O2对HL-60细胞DNA中8-羟基鸟嘌呤含量影响的研究

目的与方法：本文采用气相色谱／氢火焰离子检测器（ＧＣ／ＦＩＤ）和气相色谱－质谱仪选择性离子检测器（ＣＧＣ／ＭＳ－ＳＩＭ）探讨Ｈ２Ｏ２致ＨＬ－６０细胞氧化损伤时ＤＮＡ中氧化修饰碱基８－羟基鸟嘌呤（８－ｏｈ－Ｇ）含量的变化,观察ＨＬ－６０细胞脂质过氧化程度和细胞内还原型谷胱甘肽／氧化型谷胱甘肽（ＧＳＨ／ＧＳＳＧ）比值的变化。结果：结果显示Ｈ２Ｏ２可使ＨＬ－６０细胞丙二醛（ＭＤＡ）含量增高（Ｐ〈０．０１     

氯乙醇急性染毒对大鼠肝抗氧化酶与脂质过氧化物影响的研究

本文观察了一次性经腹腔注射氯乙醇（３０ｍｇ／ｋｇＢ．Ｗ．）的急性染毒大鼠３，６，１２，２４ｈ等四个不同时点肝脏的超氧化物歧化酶、谷胱甘肽过氧化物酶等抗氧化酶活力及脂质过氧化物—丙二醛含量的变化关系，结果发现氯乙醇急性染毒组肝脏中上述的抗氧化酶活性于所设四个时点中均比对照组低（Ｐ＜０．０１及０．０５），而同时丙二醛含量高于对照组（Ｐ＜０．０１及０．０５），提示氯乙醇急性染毒大鼠中肝脏抗氧化酶活性受氯乙醇毒性所抑制，出现肝脏脂质过氧化并造成肝损害。同时，本文也发现氯乙醇急性染毒大鼠血清中丙二醛含量与肝脏丙二醛含量存在着高度密切的正相关关系（Ｐ＜０．０１），且血清中丙二醛含量比谷丙转氨酶活性早升高，提示血清丙二醛可能可以作为检测氯乙醇急性肝损害较为敏感的指标     

A comparative study on the effects of alpha-hexachlorocyclohexane and its metabolite beta-pentachlorocyclohexene on growth and monooxygenase activities in rat liver

The present study adds support to the hypothesis that β-pentachlorocyclohexene (β-PCH) is a primary intermediate in α-hexachlorocyclohexane (α-HCH)4 metabolism in the rat. Degradation of α-HCH to β-PCH was shown to occur in vitro and in vivo, partially by non-enzymic catalysis. β-PCH accumulated in liver and adipose tissue of α-HCH treated rats, which had received the glutathione-lowering agent diethyl maleate. β-PCH disappears from the body much more rapidly than the parent compound α-HCH: about 50 per cent of a single i.p. dose were degraded within 2.5 hr, while half-life of α-HCH is known to be approximately 130 hr. To maintain equimolar liver concentrations, β-PCH must be given in doses 100-fold higher than α-HCH. β-PCH and α-HCH were fed for a period of ten days at various dose levels to give steady-state liver concentrations. It was found that β-PCH has similar hepatic effects to α-HCH: both agents induced liver growth and a phenobarbital-type pattern of monooxygenase activities, as measured by the following substrates: aminopyrine, ethylmorphine, benzphetamine, 4-nitroanisole, aniline, benzo[α]pyrene, ethoxyresorufin and 2,5-diphenyl-oxazole. Threshold doses for these effects were 30–43 μmoles/kg/day for β-PCH and 1.0–1.7 μmoles/kg/day for α-HCH. However, on the basis of molar hepatic concentrations β-PCH was a more potent inducer than α-HCH (2–10 times). Threshold concentrations ranged from 0.4 to 0.6 nmoles β-PCH/g liver and from 0.7 to 1.5 nmoles α-HCH/g liver. β-PCH concentrations in livers of rats treated even with high doses of α-HCH were below the threshold for induction of liver growth and of monooxygenase increases. It is, therefore, highly unlikely that β-PCH is responsible for the effect of α-HCH on rat livers.     

Deperoxydation de l'acide hydroperoxylinoleique par la muqueuse intestinale

In the presence of glutathione, a homogenate of rat intestinal mucosa transforms linoleic acid hydroperoxide (LOOH) into the corresponding alcohol (LOH). The K_m of the enzyme involved (a glutathione peroxidase) is 5.7 × 10^?6m. The specific activity, measured as generated LOH, was found to be 0.058 μmol/mg protein/min, six times lower than that of the liver. A mitochondrial supernatant of the mucosal homogenate had 1.5 times the activity of the initial homogenate. The reduction of 1 mol LOOH requires 2 mol glutathione. Besides this enzymatic deperoxidation, 5% of the LOOH was decomposed in both the intestinal mucosa and liver by a non-enzymatic pathway, probably involving the Fe³⁺ of the haemoproteins.     

Inhibition of glutamate-aspartate transaminase by β-methylene-DL-aspartate

β-Methylene-DL-aspartate, a new β,γ-unsaturated amino acid, is an irreversible inhibitor of soluble pig heart glutamate-aspartate transaminase (K_i ? 3 mM with respect to the L-form; limiting rate constant for inactivation ～ 0.4 min^?1). The new amino acid is the most specific inhibitor of glutamate-aspartate transaminase thus far studied. It does not inactivate pig heart glutamate-alanine transaminase, soluble rat kidney glutamine transaminase K, γ-aminobutyrate transaminase (from Pseudomonas fluorescens), glutamate decarboxylase (Escherichia coli), snake venom L-amino acid oxidase, or hog kidney D-amino acid oxidase. In addition, the following enzymes were not inhibited by β-methylene-DL-aspartate in rat tissue homogenates: γ-aminobutyrate transaminase (brain), tyrosine transaminase (liver), glutamine transaminase L (liver), asparagine transaminase (liver), ornithine transaminase (liver) or branch-chain transaminase(s) (kidney). Intraperitoneal injection of β-methylene-DL-aspartate into mice decreased kidney and liver glutamate-aspartate transaminase activities but had no effect on liver glutamate-alanine transaminase activity.     

Protection of rats against 3-butene-1,2-diol-induced hepatotoxicity and hypoglycemia by N-acetyl-l-cysteine

3-Butene-1,2-diol (BDD), an allylic alcohol and major metabolite of 1,3-butadiene, has previously been shown to cause hepatotoxicity and hypoglycemia in male Sprague-Dawley rats, but the mechanisms of toxicity were unclear. In this study, rats were administered BDD (250 mg/kg) or saline, ip, and serum insulin levels, hepatic lactate levels, and hepatic cellular and mitochondrial GSH, GSSG, ATP, and ADP levels were measured 1 or 4 h after treatment. The results show that serum insulin levels were not causing the hypoglycemia and that the hypoglycemia was not caused by an enhancement of the metabolism of pyruvate to lactate because hepatic lactate levels were either similar (1 h) or lower (4 h) than controls. However, both hepatic cellular and mitochondrial GSH and GSSG levels were severely depleted 1 and 4 h after treatment and the mitochondrial ATP/ADP ratio was also lowered 4 h after treatment relative to controls. Because these results suggested a role for hepatic cellular and mitochondrial GSH in BDD toxicity, additional rats were administered N-acetyl-l-cysteine (NAC; 200 mg/kg) 15 min after BDD administration. NAC treatment partially prevented depletion of hepatic cellular and mitochondrial GSH and preserved the mitochondrial ATP/ADP ratio. NAC also prevented the severe depletion of serum glucose concentration and the elevation of serum alanine aminotransferase activity after BDD treatment without affecting the plasma concentration of BDD. Thus, depletion of hepatic cellular and mitochondrial GSH followed by the decrease in the mitochondrial ATP/ADP ratio was likely contributing to the mechanisms of hepatotoxicity and hypoglycemia in the rat.     

Do platelet apoptosis, activation, aggregation, lipid peroxidation and platelet-leukocyte aggregate formation occur simultaneously in hyperlipidemia?

OBJECTIVES: The circulating lipoproteins may cause some abnormalities in platelet composition and function in hypercholesterolemia. The aim of this study was to investigate whether platelet apoptosis, platelet activation, platelet aggregation, platelet-leukocyte aggregate (PLA) formation and lipid peroxidation occur simultaneously in hyperlipidemia. DESIGN AND METHODS: Expression of GpIIb/IIIa (CD41a), P-selectin (CD62-P), platelet-bound fibrinogen (antifibrinogen), platelet membrane phosphatidylserine (PS), platelet-monocyte aggregates (mono-PLA) and platelet-neutrophil aggregates (neut-PLA) was measured in eight hyperlipidemic and eight normal subjects using flow cytometry. ADP (10 microM) was used to activate platelets. Furthermore, ADP induced platelet aggregation responses, platelet malondialdehyde (MDA) and glutathione (GSH) levels were determined. RESULTS: Before platelet activation, platelet CD62-P, antifibrinogen, annexin-V, mono-PLA, neut-PLA and platelet MDA levels as well as platelet aggregation responses in the hyperlipidemics were significantly higher than those in the controls (P<0.01, P<0.01, P<0.01, P<0.001, P<0.001, P<0.01, P<0.001, respectively), whereas GpIIb/IIIa expression and GSH levels were not different significantly (P > 0.05). In the control group, CD62-P, antifibrinogen and annexin-V levels increased significantly after ADP activation (P<0.05, P<0.05, P<0.01, respectively). In hyperlipidemic subjects, annexin-V expression increased significantly after activation (P<0.01), whereas expression of GpIIb/IIIa, CD62-P and antifibrinogen remained unchanged (P>0.05). The levels of total cholesterol (T-CHO), low density lipoprotein cholesterol (LDL-C), serum fibrinogen (S-FGN) and high density lipoprotein cholesterol (HDL-C) in patients were found to be correlated with platelet CD62-P, antifibrinogen, annexin-V, mono-PLA and MDA. CONCLUSIONS: In conclusion, it seems that in hyperlipidemia, some platelets are in an activated state in circulation, and that increased lipid peroxidation, early apoptosis, platelet-leukocytes aggregate formation and platelet aggregation altogether accompany this process.     

Systematically applied chemicals that damage lung tissue

A large, and increasing number of drugs and chemicals have been found which are toxic to lung following systemic administration. These agents damage lung tissue specifically, or in addition to damage to other tissues. Mechanisms explaining the pulmonary damage produced by some lung toxins have been uncovered. These include concentration of the agent within lung, the absence of adequate pulmonary detoxication systems, and bioactivation to a toxic species within specific lung cells or at distant sites followed by transport to the lung. The basic biochemical lesions underlying lung damage, responses of individual lung cells and pulmonary repair processes to the toxic agent, and species and age differences in susceptibility to lung damage have not, however, been well defined for most lung toxins. This review describes the information available on pulmonary biochemical and pathological changes associated with some of these lung-toxic agents. In addition, mechanisms proposed to explain the lung damage are discussed. The agents covered include: paraquat, the thioureas, butylated hydroxytoluene, the trialkylphosphorothioates, various lung-toxic furans and antineoplastic agents, the pyrrolizidine alkaloids, metals and organometallic compounds, amphiphilic agents, hydrocarbons, oleic acid, 3-methylindole, and diabetogenic agents. Detailed reviews on the overall toxicity of many of these agents have been published elsewhere. This review concentrates on their pulmonary toxicity. Information is presented as an overview to illustrate both the extensive literature that is available and the important questions that remain to be answered about systemic chemicals that damage lung tissue.     

谷胱甘肽和牛磺酸对汞急性肾毒性影响的实验研究

目的 探讨预先投予GSH和牛磺酸对汞急性肾毒性的影响。方法 将32只Wistar大鼠随机分为对照、HgCl2染毒、GSH HgCl2和牛磺酸 HgCl2 4组。对照组皮下注射0．9％的生理盐水,汞染毒组皮下注射2．5mg／kg的HgCl2溶液,注射容量为5ml／kg。GSH和牛磺酸组于注射相同剂量Hg口2前2h分别腹腔注射3mmoL/kg的GSH溶液和4mmol／kg的牛磺酸溶液。测定尿N-Z乙酰-β-D氨基葡萄糖苷酶(NAG)、碱性磷酸酶(ALP)、乳酸脱氢酶(LDH)活性,尿蛋白和尿肌酐含量,血清尿素氮(BUN)以及尿汞和肾汞含量。结果 与对照组比较,HgCl2染毒组尿NAG、ALP、LDH活性显著升高,尿蛋白、BUN、尿汞、肾汞含量明显增加。预先投予GSH和牛磺酸后,可使汞染毒大鼠尿NAG和ALP活性、尿蛋白和BUN含量均较HgCl2染毒组显著减低;GSH组尿汞显著低于单纯染汞组,而牛磺酸组尿汞、肾汞与汞染毒组比较差异则无显著性。结论 GSH和牛磺酸对汞致急性肾损伤有一定的保护作用。