绝经后妇女血清降钙素基因相关肽、同型半胱氨酸水平与性激素及冠心病的关系

目的　了解绝经后女性冠心病 (CHD)患者血清降钙素基因相关肽 (CGRP)、同型半胱氨酸 (Hcy)与女性激素水平的关系。方法　用断面调查方法收集经冠状动脉造影确诊的绝经后女性CHD患者 75例、非CHD患者 6 9例及同期年轻女性 6 6例 ,测定血清CGRP、Hcy及性激素水平。 结果CHD组血清Hcy水平 (15 3± 6 5 ) μmol/L高于非CHD组 (10 2± 2 8) μmol/L ,P <0 0 1。CHD组血清CGRP水平 (10 3 6± 5 9 8)ng/L低于非CHD组 (16 4 6± 5 0 7)ng/L ,P <0 0 1。CHD组女性激素水平低于非CHD组 [雌二醇 :(6 7 9± 2 4 4 ) pmol/L比 (91 7± 2 3 0 ) pmol/L ,P <0 0 1;孕酮 :(0 89± 0 4 6 )nmol/L比 (1 11± 0 4 5 )nmol/L ,P <0 0 1]。CHD组患高血压、糖尿病的比例高于非CHD组。CHD组患者年龄高于非CHD组。多因素分析证实 ,Hcy的OR大于 1,并有显著差异 ;CGRP与女性激素的OR小于 1。用前进法观察Hcy、女性激素及CGRP的偏回归系数变化 ,证实Hcy是CHD的独立危险因素 ;CGRP及女性激素是CHD的独立保护因素。结论　Hcy是导致女性CHD的独立危险因素。CGRP是CHD的独立保护因素。女性激素对Hcy及CGRP水平无明显影响     

Homocysteine-induced changes in vascular reactivity of guinea-pig pulmonary arteries: role of the oxidative stress and poly (ADP-ribose) polymerase activation

This study was aimed to examine the effects of homocysteine (Hcy) on vascular responsiveness of guinea-pig isolated pulmonary arteries and to investigate possible underlying mechanisms. In order to evaluate vascular reactivity, isometric tension studies were performed in response to potassium chloride (KCl), phenylephrine (Phe), acetylcholine (ACh), and sodium nitroprusside (SNP). Incubation of pulmonary artery rings with Hcy (10(-3)M, 180min) resulted in significant inhibition of response to ACh (an endothelium-dependent vasodilator)(E(max): 55.3+/-6.7 vs. 13.1+/-2.0(*), P<0.05) while SNP (an endothelium-independent vasodilator)-induced relaxation was not changed significantly. Furthermore, Hcy enhanced KCl- and Phe-induced contraction of pulmonary artery rings (E(max): 1568+/-81 vs. 2101+/-145(*)mg for KCl and 1081+/-101 vs. 1544+/-117(*)mg for Phe, P<0.05). Pulmonary artery ring contractions induced by stepwise addition to Ca(2+) to high KCl solution with no Ca(2+) were also significantly augmented by Hcy incubation (E(max): 1750+/-121 vs. 2295+/-134(*)mg, P<0.05). To investigate mechanisms of Hcy action, additional sets of experiments involving rings incubation with Hcy alone or with addition of Tiron (an intracellular superoxide anion scavenger, 10(-2)M), PJ34 (an inhibitor of polyADP-ribose polymerase, 3x10(-6)M), and combination of two antioxidant enzymes superoxide dismutase (SOD, 100U/ml) and catalase (CAT, 120U/ml) for 180min. The findings of our study clearly show that all these co-treatments significantly prevented the development of endothelial dysfunction induced by Hcy. Furthermore, the effect of Hcy on KCl- and Phe-induced contraction was significantly inhibited by the concomitant incubation with either SOD plus CAT, Tiron or PJ34. This study demonstrates that Hcy causes a significant alteration in vascular reactivity of pulmonary arteries, and this alteration seems to be via oxidative stress in pulmonary artery endothelium with subsequent DNA damage and activation of poly(ADP-ribose) polymerase (PARP) pathway.     

衰老大鼠急性肺损伤诱导肝功能受损的研究

目的　观察脂多糖 (LPS)致衰老大鼠的急性肺损伤 (ALI)是否可进一步诱发肝功能受损及银杏叶提取物 (GBE)对其是否有保护作用。方法　雄性Wistar大鼠 3 0只复制成衰老模型。再随机分成对照组 (静脉注射生理盐水 ) ;LPS组 (静脉注射LPS)及GBE +LPS组 (注LPS前 7天开始每天GBE灌胃 1次 )。注LPS后 2、6h收集血液并取肺、肝。制备肺、肝组织匀浆待测。结果　衰老大鼠在注射LPS后 2、6h时形成ALI。对照组注射LPS表明 ,2h血中总胆红素含量及谷丙转氨酶 (GPT)活性为(10 9± 0 6)mg/L、(2 6± 3 )U ,LPS 6h组为 (3 0 1± 2 1)mg/L、(88± 12 )U ,两组比较差异有显著性 (P均<0 0 0 1) ;对照组注射LPS表明 ,2h血和肺组织中每毫克蛋白中丙二醛 (MDA)含量分别为 (15 9±1 8) μmol/L、(18 8± 2 1)nmol,LPS 2h组为 (2 2 1± 1 9) μmol/L、(2 8 8± 3 1)nmol,两组比较差异有显著性 (P均 <0 0 0 1) ;而每毫克蛋白血和肺组织中超氧化物歧化酶 (SOD)活性对照组分别为 (2 5 5±2 6)mU/L、(3 6 1± 2 4)U ,LPS 2h组分别为 (2 0 6± 1 9)mU/L、(3 2 0± 2 7)U ,两组比较差异有显著性(P <0 0 1和 0 0 5 )。对照组注射LPS表明 ,2h时肺组织中每毫克蛋白中谷胱甘肽过氧化物酶 (GSH PX)及Na+ K+ ATP酶活性     

Correlation of plasma homocysteine level with arterial stiffness and pulse pressure in hemodialysis patients

Elevated plasma homocysteine, arterial stiffness, and increased pulse pressure (PP) are independently associated with higher cardiovascular risk in patients with end-stage renal disease. The aim of this study is to investigate the influence of plasma homocysteine on arterial stiffness and PP in hemodialysis (HD) patients. One hundred and nine HD patients were stratified into three groups by plasma homocysteine levels: low (11.2-20.8 micromol/L), middle (21.2-25.1 micromol/L), and high tertiles of plasma homocysteine (Hcy) group (25.2-43.9 micromol/L). Using a computerized oscillometry, we measured the arterial stiffness index (ASI) and blood pressure (BP) hemodynamic parameters in the brachial artery. The high Hcy group exhibited a higher ASI (110.4+/-129.5 versus 46.2+/-17.5, mean+/-S.E., P<0.01), PP (59.7+/-23.1 versus 43.3+/-16.3 mmHg, P<0.01), and age (57.8+/-14.1 versus 49.9+/-12.7 years, P<0.05) compared with the low Hcy group. Plasma homocysteine was significantly correlated with ASI (r=0.25, P<0.001), PP (r=0.33, P<0.001), systolic BP (r=0.31, P<0.001), and age (r=0.24, P<0.05). Serum ferritin was significantly correlated with ASI (r=0.24, P<0.05) and PP (r=0.23, P<0.05). ASI was also correlated with PP (r=0.64, P<0.001). Multiple regression analyses showed that both plasma homocysteine and serum ferritin had significant associations with ASI (beta=4.246, P=0.007 and beta=0.024, P=0.006, respectively), and with PP (beta=1.089, P=0.002 and beta=0.005, P=0.005, respectively) independent of other classic risk factors for atherosclerosis. In conclusion, plasma homocysteine, along with serum ferritin, may act as an important predictor for arterial stiffness and PP in HD patients.     

Metabolic insights into the hepatoprotective role of N-acetylcysteine in mouse liver

The hepatoprotective mechanisms of N-acetylcysteine (NAC) in non-acetaminophen-induced liver injury have not been studied in detail. We investigated the possibility that NAC could affect key pathways of hepatocellular metabolism with or without changes in glutathione (GSH) synthesis. Hepatocellular metabolites and high-energy phosphates were quantified from mouse liver extracts by 1H- and 31P-NMR (nuclear magnetic resonance) spectroscopy. 13C-NMR-isotopomer analysis was used to measure [U-13C]glucose metabolism through pyruvate dehydrogenase (PDH) and pyruvate carboxylase (PC). NAC (150-1,200 mg/kg) increased liver concentrations of GSH from 8.60 +/- 0.48 to a maximum of 12.95 +/- 1.03 micromol/g ww, whereas hypotaurine (HTau) concentrations increased from 0.05 +/- 0.02 to 9.95 +/- 1.12 micromol/g ww. The limited capacity of NAC to increase GSH synthesis was attributed to impaired glucose metabolism through PC. However, 300 mg/kg NAC significantly increased the fractional 13C-enrichment in Glu (from 2.08% +/- 0.26% to 4.00% +/- 0.44%) synthesized through PDH, a key enzyme for mitochondrial energy metabolism. This effect could be uncoupled from GSH synthesis and was associated with the prevention of liver injury induced by tert-butylhydroperoxide and 3-nitropropionic acid. In conclusion, NAC (1) has a limited capacity to elevate GSH synthesis; (2) increases HTau formation linearly; and (3) improves mitochondrial tricarboxylic acid (TCA) cycle metabolism by stimulation of carbon flux through PDH. This latter effect is independent of the capacity of NAC to replete GSH stores. These metabolic actions, among other yet unknown effects, are critical for NAC's therapeutic value and should be taken into account when deciding on a wider use of NAC.     

Potential effects of L-NAME on alcohol-induced oxidative stress

AIM: Nitric oxide (NO) is a highly reactive oxidant synthesized from L-arginine by nitric oxide synthase (NOS). NO may cause injury through the generation of potent radicals. Nw-nitro-L-arginine methyl ester (L-NAME) is a non-selective inhibitor of NOS. We aimed to evaluate whether L-NAME treatment had protective effects against oxidative stress in rats intragastrically fed with ethanol during a 4 wk-period. METHODS: Thirty-six male Wistar rats were divided into 3 equal groups: group 1 (control group-isocaloric dextrose was given), group 2 (6 g/kg·d ethanol-induced group) and group 3 (both ethanol 6 g/kg·d and L-NAME 500 mg/L in drinking water-given group). Animals were sacrificed at the end of 4 wk-experimental period, and intracardiac blood and liver tissues were obtained. Biochemical measurements were performed both in plasma and in homogenized liver tissues. Alanine amino transferase (ALT), aspartate amino transferase (AST), malondialdehyde (MDA), NO, superoxide dismutase (SOD), catalase (CAT) and glutathione (GSH) levels were measured by spectrophotometry. RESULTS: ALT and AST in group 2 (62 U/L and 128 U/L, respectively) were higher than those in group 1 (24 U/L and 38 U/L) and group 3 (37 U/L and 81 U/L) (P<0.001 for both). Plasma and tissue levels of MDA in group 2 (4.66 μmol/L and 0.55 μmol/mg protein) were higher than in group 1 (2.65 μmol/L and 0.34 nmol/mg protein) and group 3 (3.43 μmol/L and 0.36 nmol/mg protein) (P<0.001 for both). Plasma and liver tissue levels of NO in group 2 (54.67 μmol/L and 586.50 nmol/mg protein) were higher than in group 1 (34.67 μmol/L and 435.33 nmol/mg protein) and group 3 (27.50 μmool/L and 412.75 nmol/mg protein ) (P<0.001 for both). Plasma and liver tissue SOD activities in group 2 (15.25 U/mL and 5.38 U/ mg protein, respectively) were lower than in group 1 (20.00 U/mL and 8.13 U/ mg protein) and group 3 (19.00 U/mL and 6.93 U/ mg protein) (P<0.001 for both). Plasma and liver tissue CAT activities in group 2 (145 U/mL and 37 U/ mg protein, respectively) were lower than in group 1 (176 U/mL and 73 U/mg protein) and group 3 (167 U/mL and 61 U/mg protein) (P<0.001 for both). Meanwhile, erythrocytes and liver tissue levels of GSH in group 2 (4.12 mg/g Hb and 5.38 nmol/mg protein, respectively) were lower than in group 1 (5.52 mg/g Hb and 4.49 nmol/mg protein) and group 3 (5.64 mg/g Hb and 4.18 nmol/mg protein) (P<0.001 for both). CONCLUSION: Our findings show that L-NAME may produce a restorative effect on ethanol-induced liver damage via decreasing oxidative stress and increasing antioxidant status.     

Homocysteine-induced inhibition of endothelium-dependent relaxation in rabbit aorta: role for superoxide anions

Hyperhomocysteinemia is associated with endothelial dysfunction, although its mechanism is unknown. Isometric tension recordings and lucigenin chemiluminescence were used to assess the effects of homocysteine exposure on endothelium-dependent and -independent relaxation in isolated rabbit aortic rings and superoxide anion (O(2)(-)) production by cultured porcine aortic endothelial cells, respectively. Homocysteine (0.1 to 10 mmol/L) produced a significant (P<0.001) concentration- and time-dependent inhibition of endothelium-dependent relaxation in response to both acetylcholine and the calcium ionophore A23187. Only the intracellular O(2)(-) scavenger 4,5-dihydroxy-1,3-benzene disulfonic acid (Tiron, 10 mmol/L) significantly (P<0.001) inhibited the effect of homocysteine on acetylcholine- and A23187-induced relaxation. Incubation of porcine aortic endothelial cells with homocysteine (0.03 to 1 mmol/L for up to 72 hours) caused a significant (P<0.001) time-dependent increase in the O(2)(-) released by these cells on the addition of Triton X-100 (1% [vol/vol]), with levels returning to values comparable to those of control cells at the 72-hour time point. These changes in O(2)(-) levels were associated with a time-dependent increase in endothelial cell superoxide dismutase activity, becoming significant (P<0.001) after 72 hours. Furthermore, the homocysteine-induced increase in endothelial cell O(2)(-) levels was completely inhibited (P<0.001) by the concomitant incubation with either Tiron (10 mmol/L), vitamin C (10 micromol/L), or vitamin E (10 micromol/L). These data suggest that the inhibitory effect of homocysteine on endothelium-dependent relaxation is due to an increase in the endothelial cell intracellular levels of O(2)(-) and provide a possible mechanism for the endothelial dysfunction associated with hyperhomocysteinemia.     

Physiological increments in plasma homocysteine induce vascular endothelial dysfunction in normal human subjects

We hypothesized that physiological increments in plasma homocysteine after low-dose oral methionine or dietary animal protein induce vascular endothelial dysfunction and that there is a graded, inverse relationship between homocysteine concentration and endothelial function. We studied 18 healthy volunteers aged 18 to 59 years. Brachial artery flow-mediated and glyceryltrinitrate-induced dilatation were measured after 1) oral L-methionine (10, 25, and 100 mg/kg), 2) dietary animal protein (lean chicken 551+/-30 g, comprising 3.2+/-0.2 g methionine), and 3) methionine-free amino acid mix (100 mg/kg). Methionine (10, 25, and 100 mg/kg) induced a dose-related increase in homocysteine (9.4+/-1.3 to 12.2+/-2.1, 17. 6+/-2.6, and 26.1+/-4.2 micromol/L, respectively; P<0.001) and a reduction in flow-mediated dilatation (4.1+/-0.8 to 2.1+/-0.8, 0. 3+/-0.8, and -0.7+/-0.8%, respectively; P<0.001) at 4 hours. Compared with usual meal, animal protein increased plasma homocysteine (9.6+/-0.8 to 11.2+/-0.9 micromol/L, P=0.005) and reduced flow-mediated dilatation (4.5+/-0.7% to 0.9+/-0.6%, P=0.003). Methionine-free amino acid mix did not induce any changes. Glyceryltrinitrate-induced dilatation was unchanged throughout. In this study, small physiological increments in plasma homocysteine after low-dose methionine and dietary animal protein induced vascular endothelial dysfunction. We propose that protein intake-induced increments in plasma homocysteine may have deleterious effects on vascular function and contribute to the development and progression of atherosclerosis.     

Heme oxygenase-1 induction does not improve vascular relaxation in angiotensin II hypertensive mice

BACKGROUND: Induction of heme oxygenase-1 (HO-1) attenuates the development of angiotensin II (Ang II)-dependent hypertension in mice. However, the mechanism by which HO-1 lowers blood pressure in this model is not clear. This study was designed to determine whether induction of HO-1 results in an improvement in vascular relaxation in Ang II hypertensive mice. METHODS: Mice were treated with either of the vehicles (control), the HO-1 inducer cobalt protoporphyrin (CoPP;50 mg/kg), Ang II(1 microg/kg/min, 14 days), or Ang II + CoPP. CoPP was administered as a single bolus dose 2 days prior to subcutaneous implantation of the osmotic minipump containing Ang II. Vascular relaxation was examined in isolated carotid arteries precontracted with the thromboxane mimetic U46619 (0.4 microg/ml). RESULTS: Endothelial dependent relaxation to acetylcholine (ACh; 1 micromol/l) was significantly impaired in Ang II-treated mice compared to control mice (56 +/- 3% vs. 40 +/- 4%, P < 0.05, n > or = 6). Similarly, endothelial independent relaxation to sodium nitroprusside (SNP; 1 micromol/l) was significantly impaired in Ang II mice (56 +/- 6% vs. 28 +/- 6%, P < 0.05, n > or = 6). Relaxation in response to the carbon monoxide donor, CORM-A1 (100 micromol/l), was attenuated after Ang II treatment (75 +/- 7% vs. 59 +/- 7%,P < 0.05, n > or = 6). CoPP treatment induced HO-1 but not HO-2 protein in the aorta, as measured by western blot analysis. CoPP treatment had no effect on vascular responses in control mice and did not improve ACh (26 +/- 5%, n = 15), SNP (23 +/- 4%, n = 15), or CORM-A1 (46 +/- 7%, n = 10) dependent relaxation in Ang II treated mice. CONCLUSIONS: These results suggest that induction of HO-1 lowers Ang II-dependent hypertension through a mechanism independent of improved vascular relaxation.     

Effect of chemotherapy on serum end-products of lipid peroxidation in patients with small cell lung cancer: association with treatment results

Many anti-cancer drugs induce formation of lipid peroxidation products that are toxic for lung cancer cells in vitro. We tested whether changes of serum thiobarbituric acid reactive substances (TBARs) and Schiff's bases (SB) are associated with treatment efficacy in 37 small cell lung cancer (SCLC) patients. Subjects received carboplatin (350 mg/m2, i.v.-Day 1), vincristine (1.3 mg/m2, i.v.-Day 1), and etoposide (120 mg/m2, oral dose-Days 1-4). Then 5 subsequent cycles were repeated at 21-day intervals. Serum TBARs and SB were measured fluorimetrically before and 6, 24h after introduction of the 1st, 3rd and 6th cycles. TBARs and SB levels rose 24 h after 1st chemotherapy in the whole group (2.5+/-1.4 vs. 4.2+/-2.0 micromol/dl, P<0.001 and 26.3+/-16.7 vs. 29.7+/-9.8U(430)/ml, P<0.01, respectively) and the highest increments were in 19 patients with complete or partial response after 1st, 3rd and 6th cycles. In 9 subjects with progressive disease occurring before the 2nd cycle (early progression) TBARs and SB decreased 6 and 24h after the 1st cycle (4.3+/-1.2 vs. 3.4+/-1.4, P<0.05 vs. 2.7+/-0.9 micromol/dl, P<0.05 and 50.2+/-17.0 vs. 36.7+/-13.2, P<0.05 vs. 36.5+/-13.4 U(430)/ml, P<0.01, respectively). Patients survival correlated with the 1st cycle-induced TBARs (r=0.49, P<0.001) and SB (r=0.56, P<0.002) increments. Subjects with negative SB and TBARs increments (n=8) had shorter survival than those (n=29) with positive increments in lipid peroxidation products (log rank test P<0.005). Monitoring of circulatory TBARs and SB may be helpful for screening of SCLC patients with high risk of early disease progression and chemotherapy failure.     

Erythrocyte susceptibility to oxidative stress and antioxidant status in patients with type 1 diabetes

In this study, malondialdehyde (MDA) level as an index of erythrocyte susceptibility to oxidative stress and antioxidant defense system (glutathione level (GSH), glutathione peroxidase enzyme activity (GPx) in erythrocytes and ferric reducing ability of plasma (FRAP) as the total plasma antioxidant capacity were measured in 35 patients with type 1 diabetes and 28 age and sex-matched normal subjects. MDA level was significantly elevated in diabetic patients (650.9+/-144.3 nmol/g versus 476.5+/-138.5 nmol/g Hb, P<0.001). The level of MDA was positively correlated with duration of diabetes (r= 0.29, P<0.05) and HbA(1C) (r= 0.39, P<0.05) and negatively with FRAP (r= -0.3, P<0.05). The level of GSH and FRAP were lower in patients than controls (7.05+/-1.6 micromol/g versus 8.24+/-0.9 micromol/g Hb, and 389.05+/-82.3 micromol/l versus 520.4+/-124.1 micromol/l, respectively, P<0.001). GPx activity was not significantly different between the two groups. GSH and FRAP were negatively correlated with HbA(1C) (r= -0.334, P<0.01 and r= -0.5, P<0.01, respectively). In conclusion, there seems to be an increased susceptibility to oxidative stress and decreased antioxidant defense in patients with type 1 diabetes, which may be due to poor glycemic control.     

Strontium ranelate decreases plasma homocysteine levels in postmenopausal osteoporotic women

We analyzed the effect of strontium ranelate treatment on plasma homocysteine (Hcy) levels in postmenopausal osteoporotic women. Forty-nine postmenopausal women diagnosed with osteoporosis with a mean age of 54.07 +/- 7.5 years (range 40-70) who visited our menopause clinic were participated in this prospective study. Patients with bone mineral density (BMD) at least 2.5 SD below the average value in young adults (T score < -2.5) were considered to have osteoporosis. Patients received strontium ranelate 2 g/day (Servier) orally with additional calcium supplements. Fasting plasma Hcy levels were assessed at baseline, 3, 6 and 12 months of the therapy with strontium ranelate. The mean plasma Hcy level (10.45 micromol/l) after 3 months of therapy was significantly lower compared to the basal plasma Hcy level (12.61 micromol/l) (P = 0.002). The plasma homocysteine level (10.54 micromol/l) of the 43 patients that were present at the 6 months of the therapy was also significantly lower compared to the basal plasma Hcy level (P = 0.005). At the end of the 12 months of the study, there were 42 patients. The plasma homocysteine level (10.107 micromol/l) at 12 months of therapy was also significantly lower compared to the basal Hcy level (P < 0.001). Strontium ranelate 2 g/day treatment for 1 year significantly decreases plasma Hcy levels in postmenopausal women with osteoporosis. Since the increased Hcy levels could lead to an increase risk of osteoporosis and fracture risk, this effect of strontium ranelate on Hcy level may cause additional benefit in terms of reducing the risk of fracture.     

Intravenous administration of glutathione protects parenchymal and non-parenchymal liver cells against reperfusion injury following rat liver transplantation

AIM:To investigate the effects of intravenous administration of the antioxidant glutathione (GSH) on reperfusion injury following liver transplantation.METHODS:Livers of male Lewis rats were transplanted after 24 h of hypothermic preservation in University of Wisconsin solution in a syngeneic setting. During a 2-h reperfusion period either saline (controls,n=8) or GSH (50 or 100μmol/(h&#183;kg),n=5 each) was continuously administered via the jugular vein.RESULTS:Two hours after starting reperfusion plasma ALT increased to 1 457&#177;281U/L (mean&#177;SE) in controls but to only 908_+187 U/L (P&lt;0.05) in animals treated with 100μmol GSH/(h&#183;kg).No protection was conveyed by 50μmol GSH/(h&#183;kg).Cytoprotection was confirmed by morphological findings on electron microscopy:GSH treatment prevented detachment of sinusoidal endothelial cells (SECs) as well as loss of microvilli and mitochondrial swelling of hepatocytes. Accordingly, postischemic bile flow increased 2-fold. Intravital fluorescence microscopy revealed a nearly complete restoration of sinusoidal blood flow and a significant reduction of leukocyte adherence to sinusoids and postsinusoidal venules. Following infusion of 50μmol and 100 μmol GSH/(h&#183;kg),plasma GSH increased to 65&#177;7mol/L and 97&#177;18μmol/L,but to only 20&#177;3mol/L in untreated recipients.Furthermore, plasma glutathione disulfide (GSSG) increased to 7.5&#177;1.0mol/L in animals treated with 100μmol/(h&#183;kg) GSH but infusion of 50μmol GSH/(h&#183;kg) did not raise levels of untreated controls (1.8&#177;0.5mol/L vs 2.2&#177;0.2mol/L).CONCLUSION:Plasma GSH levels above a critical level may act as a “sink” for ROS produced in the hepatic vasculature during reperfusion of liver grafts.Therefore, GSH can be considered a candidate antioxidant for the prevention of reperfusion injury after liver transplantation, in particular since it has a low toxicity in humans.     

对氧磷酶基因多态性及血浆同型半胱氨酸硫内酯复合物水平与冠心病的关系

目的探讨对氧磷酶(PON)基因多态性(PON1 T-107C、PON2 C311S)及血浆同型半胱氨酸(Hcy)、同型半胱氨酸硫内酯(HTL)复合物水平与冠心病发病的关系。方法对203例经冠状动脉造影证实为冠心病的患者及117例经冠状动脉造影证实无冠状动脉病变的对照者进行研究,采用竞争性 ELISA 法测定血浆 HTL 复合物水平;采用高压液相色谱法测定血浆 Hcy 的水平;采用多聚酶链反应-限制性内切酶片段长度多态性(PCR-RFLP)分析 PON 基因中 PON1 T-107C 和 PON2 C311S基因多态性。结果冠心病组血浆 Hcy 和 HTL 复合物水平明显高于对照组(P<0.01);PON1 T-107C 基因型与等位基因频率分布在冠心病组与对照组间比较差异无统计学意义(P>0.05);而PON2 C311S 的 SS 基因型分布在冠心病组低于对照组(P<0.05),但等位基因频率分布两组间差异无统计学意义(P>0.05);当两位点的等位基因 T、S 同时出现时(即 CT/TF+CS/SS 基因型)血浆 Hcy及 HTL 复合物水平较 CC+CS/CC 或 CT+CC 基因型明显降低[Hcy(11.83±4.76)μmol/L 与(15.32±10.32)μmol/L;HTL(24.36±9.30)U/ml 与(32.05±10.44)U/ml],差异有统计学意义(P<0.05)。冠心病合并2型糖尿病组与冠心病无糖尿病组及对照组相比,PON2基因型分布差异有统计学意义,冠心病合并2型糖尿病患者中 C 等位基因频率明显增高(P<0.05)。结论血浆 Hcy 和 HTL 复合物水平升高可能是冠心病发病的独立危险因素,PON1 T 等位基因和 PON2 S 等位基因同时出现可能在动脉粥样硬化形成过程中起到保护作用,而 PON2 C311S 多态性的 C 等位基因存在可能与冠心病患者合并2型糖尿病的几率增高相关。     

风湿性疾病中高同型半胱氨酸血症的临床研究

目的　分析多种风湿性疾病患者血浆中同型半胱氨酸(Hcy)水平及其相关因素。方法脊柱关节病(uSpA)患者和 62例正常对照的Hcy、VitB12、叶酸的水平和亚甲基四氢叶酸还原酶(MTHFR)基因 677位的多态性。结果　(1)各疾病组Hcy水平分别为:SLE组 (19 04±6 86)μmol/L,RA组(19 07±7 43)μmol/L,AS组(16 47±6 50)μmol/L,uSpA组(16 59±6 72)μmol/L,对照组(12 24±3 58)μmol/L,各疾病组Hcy水平明显较对照组高,其差异有统计学意义 (P<0 01 ); ( 2 )Hcy与VitB12、叶酸呈负相关,相关系数分别为-0 701和-0 443,P<0 01; (3)MTHFR基因 677位C→T的突变使Hcy水平升高, CC型 ( 13 41±5 78 )μmol/L,CT型 ( 16 81±4 22 )μmol/L,TT型(20 88±6 60)μmol/L,P<0 01;TT基因型是高Hcy血症的易感基因 (OR=84 46,P<0 05);TT基因型还是SLE的易感基因(OR=7 56,P<0 05)。结论　(1)SLE、RA、AS、uSpA4种疾病患者普遍存在高Hcy血症。(2)导致高Hcy血症的原因可能有叶酸、VitB12的水平降低和MTHFR基因的突变。(3)TT型基因是Hcy异常升高的易感基因,也是SLE的易感基因。     

Decrease of carotid intima-media thickness in patients at risk to cerebral ischemia after supplementation with folic acid, Vitamins B6 and B12

OBJECTIVE: Hyperhomocysteinemia is associated with atherosclerotic risk. Although vitamins can lower homocysteine (Hcy), information about effects on atherosclerosis is scarce. METHODS: We used carotid intima-media thickness (IMT) as an accepted marker of atherosclerotic changes. Fifty patients (60 +/- 8 years) with IMT> or =1 mm were included. In a double blind, randomized trial they received daily 2.5 mg folic acid, 25 mg Vitamin B6, and 0.5mg Vitamin B12 or placebo for 1 year. RESULTS: In the treatment group, Hcy decreased from 10.50 +/- 3.93 to 6.56 +/- 1.53 micromol/l (P < 0.0001), whereas it remained unchanged in the placebo group (10.76 +/- 2.36 versus 10.45+/-3.30 micromol/l). IMT decreased from 1.50 +/- 0.44 to 1.42 +/- 0.48 mm (P = 0.034) in the treatment group, whereas it increased from 1.47 +/- 0.57 to 1.54 +/- 0.71 mm in the placebo group. The mean individual changes of IMT between both groups differed significantly (-0.08 +/- 0.17 versus 0.07 +/- 0.25 mm, P = 0.019). Multiple regression analysis revealed that the observed effect on IMT depended only on medication. CONCLUSIONS: Vitamin supplementation significantly reduces IMT in patients at risk. This effect is independent of Hcy concentration.     

Administration of glutathione in patients with type 2 diabetes mellitus increases the platelet constitutive nitric oxide synthase activity and reduces PAI-1

Several studies suggest that nitric oxide (NO) production is impaired in diabetes mellitus. Reduced levels of NO could contribute to cardiovascular mortality. Furthermore, NO synthesis is impaired in glutathione (GSH)-depleted human umbilical vein endothelial cells and GSH is reduced in patients with type 2 diabetes mellitus (T2DM). We tested the hypothesis that treatment with GSH may improve platelet constitutive NO sinthase (cNOS) activity in patients with T2DM. Fifteen patients with T2DM underwent a treatment with GSH 600 mg/day i.m. for 10 days. With respect to the basal values on the 10th day of treatment, the red blood cell GSH concentration and platelets cNOS increased (1.4+/-0.1 vs 1.9+/-0.1 micromol/10(10) RBC, p<0.001 and 0.7+/-0.1 vs 2.9+/-0.2 fmol x min(-1) x 10(-9) PLTs, p<0.001, respectively) and the plasma PAI-1 levels diminished (81.4+/-3.7 vs 68.7+/-4.0 ng/ml, p<0.002). A negative correlation between the cNOS and the PAI-1 was found on the basal values. After a wash-out of 30 days the values of red blood cell GSH concentration, platelet cNOS activity and PAI-1 Ag returned to the basal levels. These data suggest that the administration of GSH, in patients with T2DM, is able to improve platelet cNOS activity together with a reduction of PAI-1.     

N-acetylcysteine attenuates oxidative stress and liver pathology in rats with non-alcoholic steatohepatitis

AIM To evaluate attenuating properties of N-acetylcysteine (NAC) on oxidative stress and liver pathology in rats with non-alcoholic steatohepatitis (NASH).METHODS Male Sprague-Dawley rats were randomly divided into three groups. Group 1 (control, n = 8) was free accessed to regular dry rat chow (RC) for 6 wk.Group 2 (NASH, n = 8) was fed with 100% fat diet for 6 wk. Group 3 (NASH NAC20, n = 9) was fed with 100% fat diet plus 20 mg/kg per day of NAC orally for 6 wk. All rats were sacrificed to collect blood and liver samples at the end of the study.RESULTS The levels of total glutathione (GSH)and hepatic malondialdehyde (MDA) were increased significantly in the NASH group as compared with the control group (GSH; 2066.7 ± 93.2 vs 1337.5 ± 31.5 μmol/L and MDA; 209.9± 43.9 vs 3.8 ±1.7 μmol/g protein, respectively, P ＜ 0.05). Liver histopathology from group 2 showed moderate to severe macrovesicular steatosis, hepatocyte ballooning, and necroinflammation.NAC treatment improved the level of GSH (1394.8 ± 81.2 μmol/L, P ＜ 0.05), it did not affect MDA (150.1 ± 27.0 μmol/g protein), but led to a decrease in fat deposition and necroinflammation.CONCLUSION NAC treatment could attenuate oxidative stress and improve liver histology in rats with NASH.     

Ascorbic acid and glutathione modulate the biological activity of S-nitrosoglutathione

Ascorbic acid and glutathione (GSH) are important determinants of the intracellular redox state, and both are known to accelerate the decomposition of S-nitrosoglutathione (GSNO), an endogenous adduct of nitric oxide (NO). The implications of these observations for GSNO bioactivity are not yet clear. We investigated the effect of ascorbic acid and GSH on GSNO bioactivity by using a bioassay with isolated segments of guinea pig aorta suspended in organ chambers. Arterial segments demonstrated relaxation to GSNO (0.1 micromol/L) that was significantly enhanced by 300 micromol/L ascorbic acid (71+/-6% versus 53+/-6%, P<0.05) but not GSH. Both ascorbic acid and GSH significantly shortened the duration of arterial relaxation in response to 0.1 micromol/L GSNO (from >120 minutes to 22.5+/-3.5 and 36.3+/-4.3 minutes, respectively; P<0.05), consistent with accelerated decomposition of GSNO that was confirmed spectrophotometrically. The effect of ascorbic acid was abrogated by either DTPA or the copper(I)-specific agent bathocuproine but not deferoxamine, indicating a dependence on the availability of redox-active copper. Consistent with this notion, the action of ascorbic acid on GSNO bioactivity was also supported by copper-zinc superoxide dismutase, a physiologically relevant source of copper. In contrast, the effect of GSH on GSNO degradation and GSNO-mediated arterial relaxation was independent of transition metal ions, because DTPA had no effect. These data indicate that both ascorbic acid and GSH modulate GSNO bioactivity and suggest a distinction between the mechanism of GSNO degradation by ascorbic acid or GSH. Whereas both ascorbic acid and GSH accelerate the degradation of GSNO, only ascorbic acid is dependent on the presence of transition metal ions.     

New insights on myocardial pyridine nucleotides and thiol redox state in ischemia and reperfusion damage

OBJECTIVE: to investigate the changes of pyridine nucleotides and thiol redox state in cardiac tissue following ischemia and reperfusion. NADH/NAD and NADPH/NADP redox couples were specifically studied and the influence of NADPH availability on cellular thiol redox was also investigated. METHODS: isolated rabbit hearts were Langendorff perfused and subjected to a protocol of ischemia and reperfusion. An improved technique for extraction and selective quantitation of pyridine nucleotides was applied. RESULTS: ischemia and reperfusion induced an increase in diastolic pressure, limited recovery in developed pressure and loss of creatine phosphokinase. Creatine phosphate and ATP were decreased by ischemia and only partially recovered during reperfusion. NADH was increased (from 0. 36+/-0.04 to 1.96+/-0.15 micromol/g dry wt. in ischemia, P<0.001), whereas NADPH decreased during ischemia (from 0.78+/-0.04 to 0. 50+/-0.06 micromol/g dry wt., P<0.01) and reperfusion (0.45+/-0.03 micromol/g dry wt.). Furthermore, we observed: (a) release of reduced (GSH) and oxidised glutathione (GSSG) during reperfusion; (b) decreased content of reduced sulfhydryl groups during ischemia and reperfusion (GSH: from 10.02+/-0.76 to 7.11+/-0.81 nmol/mg protein, P<0.05, and to 5.48+/-0.57 nmol/mg protein; protein-SH: from 280.42+/-12.16 to 135.11+/-17.00 nmol/mg protein, P<0.001, and to 190.21+/-11.98 nmol/mg protein); (c) increased content in GSSG during reperfusion (from 0.17+/-0.02 to 0.36+/-0.02 nmol/mg protein, P<0.001); (d) increased content in mixed disulphides during ischemia (from 6.14+/-0.13 to 8.31+/-0.44 nmol/mg protein, P<0.01) and reperfusion (to 9.87+/-0.82 nmol/mg protein, P<0.01). CONCLUSIONS: under severe low-flow ischemia, myocardial NADPH levels can decrease despite the accumulation of NADH. The reduced myocardial capacity to maintain NADPH/NADP redox potential can result in thiol redox state changes. These abnormalities may have important consequences on cellular function and viability.