In young post-myocardial infarction male patients elevated plasminogen activator inhibitor-1 correlates with insulin resistance and endothelial dysfunction

Classical and nonclassical risk factors contribute to the development of myocardial infarction (MI) in young patients. The aim of the present study was to find out whether insulin resistance and impaired fibrinolysis, with increased plasminogen activator inhibitor (PAI-1), are present in young male post-MI patients, and their relation to additional markers of cardiovascular risk such as endothelial dysfunction (ED) and intima-media thickness (IMT). Forty-one male patients (on average 44 years old) in the stable phase after MI were recruited, with 25 healthy males who did not differ from patients regarding age as controls. Body mass index (BMI) and waist-to-hip ratio were measured and insulin resistance was calculated. Several coagulation/fibrinolytic parameters and inflammation markers were measured. ED was estimated by ultrasound measurement of the flow-mediated dilatation (FMD) of the brachial artery, and IMT was measured on the common carotid artery. BMI was increased in post-MI patients in comparison with healthy controls. Compared with the control group, in post-MI patients PAI-1 antigen (13.8 ± 10.6 vs 9.1 ± 7.6 ng/ml, P = 0.042), PAI-1 activity (14.8 ± 10.8 vs 9.0 ± 8.0 IU/ml, P = 0.015), and fibrinogen were significantly elevated. In patients increased PAI-1, antigen and activity were both significantly positively related to insulin resistance. We found an important negative relation between PAI-1 antigen and FMD (r = ?0.32, P = 0.04) and between PAI-1 activity and FMD (r = ?0.39, P = 0.01). Our results suggest that PAI-1 can be a link between obesity, insulin resistance, and MI in young patients. It is thus concluded that impaired fibrinolysis with increased PAI-1 may be an important nonclassical risk factor for MI, particularly in young males with increased BMI and insulin resistance.     

Comparison of plasminogen activator inhibitor-1 concentration in insulin-resistant versus insulin-sensitive healthy women

The primary goal of this investigation was to see whether plasminogen activator inhibitor-1 (PAI-1) concentrations varied as a function of differences in insulin-mediated glucose disposal in 2 groups of healthy women matched for every other variable that might play a role in regulation of PAI-1. For this purpose, we recruited 32 healthy women, divided on the basis of their steady-state plasma glucose (SSPG) concentrations during the insulin suppression test into an insulin-resistant (SSPG=216+/-12 mg/dL, n=16) and an insulin-sensitive (94+/-6 mg/dL, n=16) group. PAI-1 antigen concentrations were significantly higher (26+/-4 versus 14+/-3 ng/mL, P<0.02) in the insulin-resistant group. In addition, fasting plasma insulin (18+/-3 versus 11+/-2 microU/mL, P<0.02) and triglyceride (160+/-19 versus 93+/-10 mg/dL, P<0.001) concentrations were higher in the insulin-resistant individuals, whereas HDL concentrations were lower (44+/-3 versus 58+/-3 mg/dL, P<0.005). However, the 2 groups were essentially identical in terms of age, menopausal status, hormone replacement therapy, body mass index (BMI), ratio of waist-to-hip girth, and blood pressure. When the experimental population was considered as 1 group, there were statistically significant correlations between PAI-1 antigen and the following variables: adjusting for differences in age and BMI, SSPG (r=0.56, P<0.001); triglyceride (r=0.39, P<0.05); and HDL cholesterol (r=-0. 65, P<0.001) concentrations. Finally, multiple regression analysis revealed the major determinants of PAI-1 to be insulin resistance, or insulin concentration, and HDL cholesterol. These results: 1) demonstrate that PAI-1 concentrations are higher in healthy, insulin-resistant women as compared with insulin-sensitive individuals, independent of differences in BMI or ratio of waist-to-hip girth; and 2) provide another mechanism by which insulin-resistant individuals are at increased thrombotic cardiovascular risk.     

Improvement by the insulin-sensitizing agent, troglitazone, of abnormal fibrinolysis in type 2 diabetes mellitus

This study evaluated abnormal fibrinolysis in diabetic patients in terms of the pathophysiological significance and reversibility by oral hypoglycemic agents. Forty-seven patients with type 2 diabetes mellitus were randomly treated for 4 weeks with glibenclamide (n = 23) or troglitazone (n = 24). Before and after treatment, glycemic control, steady-state plasma glucose and insulin (SSPG and SSPI, respectively), and markers of fibrinolysis (tissue plasminogen activator [tPA] and plasminogen activator inhibitor-1 [PAI-1]) were analyzed in each patient. Pretreatment plasma PAI-1 in diabetic patients, but not tPA, was well correlated with the severity of retinopathy assessed by the fluorescence technique. Four weeks of treatment with troglitazone significantly decreased hemoglobin A1c (HbA1c), SSPG, and PAI-1 without an alteration of tPA. The troglitazone-induced decrease in plasma PAI-1 (50.3 v28.8 micromol/L; P < .05) was correlated with HbA1c (8.80% v7.21%, r = .539, P < .01) and SSPG (16.2 v 8.97 mmol/L, r = .562, P < .01) but not with SSPI. In contrast, treatment with glibenclamide for 4 weeks also reduced the HbA1c titer to almost the same extent as troglitazone (1.38% v 1.59%), but did not change the plasma PAI-1 or SSPG titer. These results suggest that an abnormal fibrinolytic state, especially overproduction of PAI-1, may be a pathogenic factor in the development of diabetic complications such as retinopathy, which may be improved by correction of the insulin resistance with troglitazone.     

Effects of angiotensin converting enzyme and angiotensin II receptor inhibition on impaired fibrinolysis in systemic hypertension

Abnormalities in fibrinolysis have been reported in hypertension. Angiotensin converting enzyme (ACE) inhibitors have been shown to improve altered fibrinolytic balance in hypertensive patients. It has not been documented, however, whether this is due to a decrease in angiotensin II (Ang-II) generation or is a consequence of elevated local levels of bradykinin. Accordingly, the aim of this study was to determine the effects of an ACE inhibitor (perindopril) and an Ang-II receptor antagonist (losartan) on fibrinolytic kinetics.We have examined the serum levels of the plasminogen activator inhibitor type-1 (PAI-1) antigen and activity, tissue plasminogen activator (t-PA) antigen and activity, soluble thrombomodulin (sTM), and tissue factor pathway inhibitor (TFPI) before and after reaching the target blood pressure (< 140/90 mm Hg) in 13 hypertensive patients receiving perindopril (mean age 40 ± 11 years, 6 women, 7 men) and in 12 patients receiving losartan (mean age 38 ± 9 years, 6 women, 6 men). We also compared the baseline fibrinolytic activity of hypertensive patients with that of 12 normotensive control persons (mean age 40 ± 9 years, 6 women, 6 men). The mean basal plasma levels of PAI-1 antigen, PAI-1 activity, and sTM were significantly higher in the hypertensive patients than in normal controls (P < .005). The values of other analytes were similar in both groups. Increased plasma levels of PAI-1 antigen, PAI-1 activity, and sTM were reduced in patients after they were given perindopril and losartan (P < .005); the reductions in losartan-receiving group were more pronounced (P < .05). There were no significant effects on the plasma levels of t-PA antigen, t-PA activity, and TFPI in patients receiving the two therapeutic regimens (P > .05).In conclusion, chronic hypertension is associated with hypofibrinolysis. The beneficial effect of ACE inhibitors on fibrinolysis seems to be related to the blockade of Ang-II, and increased kinin activity does not appear to play a major role.     

Fibrinolytic function in diuretic-induced volume depletion

Accumulating evidence suggests that the renin-angiotensin system (RAS) may participate in the regulation of fibrinolytic function. In clinical studies, however, angiotensin-converting enzyme (ACE) inhibitors and the angiotensin II receptor antagonist losartan have failed to consistently affect endogenous fibrinolysis. Because such an effect may depend on the degree of prestimulation of the RAS, we have studied parameters of fibrinolytic function in 15 healthy volunteer subjects during baseline (day 1) and after 10 days of treatment with 25 mg of hydrochlorothiazide (HCT)/day (day 11). On the last day of the study (day 12), a single oral dose of 50 mg of losartan was given to the volunteers in addition to HCT and fibrinolytic function was assessed at the peak effect of losartan (5 h later). Plasma renin activity (PRA) was significantly stimulated during diuretic treatment (1.35 ± 0.21 v 0.34 ± 0.06 ng mL⁻¹ · h⁻¹ [P < .001]) and further increased after losartan (6.39 ± 1.16 ng mL⁻¹ · h⁻¹ [P < .001]). No effects of either the diuretic or losartan could be observed on tissue-type plasminogen activator (t-PA) antigen concentration and activity. However, 10 days of treatment with HCT significantly increased plasminogen activator inhibitor-1 (PAI-1) antigen (26.8 ± 5.8 v 21.1 ± 3.4 ng/mL [p = .037]). In addition, PAI-1 activity was also tentatively raised by HCT treatment (5.48 ± 1.82 v 3.88 ± 0.79 IU/mL [P = .067]). In spite of the marked further rise in PRA after losartan, the stimulation of PAI-1 antigen and activity was blunted by losartan (24.4 ± 3.6 ng/mL and 4.55 ± 0.99 IU/mL, respectively). Our results demonstrate that volume depletion induced by HCT treatment is associated with a rise in PAI-1. Acute administration of losartan is capable of blunting this effect, suggesting that the angiotensin II type 1 receptor may participate in this effect of angiotensin II.     

Platelet function and fibrinolytic activity in patients with bronchial asthma.

Platelets have the capacity to release mediators with potent inflammatory or anaphylactic properties. Platelet factor-4 (PF4) and beta-thromboglobulin (BTG) are two of these mediators. On the other hand, plasminogen activator inhibitor-1 (PAI-1) and tissue plasminogen activator (tPA) are two important mediators of fibrinolysis. Both mediators are secreted mainly by vascular endothelium. Plasma levels of PF4, BTG, PAI-1, and tPA may show changes in chronic inflammatory diseases such as asthma. This study examined the role of thrombocytes and the function of the endothelium in asthmatic patients during an attack and during a stable phase. Eighteen patients with known allergic asthma who came to our emergency department with an asthma attack and 14 control subjects were included in the study. Blood samples were taken after starting therapy with salbutamol inhalation. Lung function tests were performed after receiving the first emergency therapy for asthma. Plasma levels of PF4, BTG, PAI-1, tPA were determined before starting steroid therapy and after receiving 1 week of steroid therapy. Plasma levels of PF4 among patients with an asthma attack were significantly higher than those of controls (150.5+/-8.92 IU/mL vs. 92.5+/-7.63 IU/mL, p<0.001). A further increase in plasma PF4 levels was detected after steroid therapy (163.5+/-9.16 IU/mL). Plasma BTG levels of patients on admission were not statistically different from those in the control group (140.4+/-6.34 IU/mL vs. 152.2+/-8.71 IU/mL). An increase was detected after therapy (171.6+/-7.27 IU/mL) and post-treatment plasma levels were statistically meaningful versus the controls. Plasma levels of tPA and PAI were statistically higher than those in controls in asthmatic patients on admission (6.01+/-2.72 vs. 5.4+/-2.3 ng/mL for tPA and 75.2+/-27.2 ng/mL vs. 32.7+/-14.3 ng/mL for PAI-1). Further increases were detected in two parameters after 1 week of therapy with steroids (tPA levels were 6.85+/-2.96 ng/mL and PAI-1 levels were 83.5+/-29.6 ng/mL). There seems to be an increased activity of platelets during an asthma attack. Elevated PAI-1 and tPA levels may also indicate the activated endothelium in asthma. Increases of plasma levels of PAI-1 and tPA after steroid therapy need further investigation because elevated PAI-1 levels enhance airway remodeling.     

Sympathetic nerve activity and insulin sensitivity in normotensive offspring of hypertensive parents

Insulin resistance and elevated sympathetic nerve activity (SNA) are observed in young borderline hypertensive humans. A positive family history of hypertension (FH) is a strong risk factor for developing hypertension. To assess whether insulin resistance and increased sympathetic tone precede the onset of hypertension, we studied 17 young adults with and 17 without a documented family history of hypertension. Subjects were matched for age (33 ± 0.4 years in FH positive and 32 ± 0.5 years in FH negative; mean ± SE) and body mass index (BMI, 25 ± 1 kg/m² in both FH positive and FH negative subjects). We measured blood pressure (BP), heart rate (HR), muscle sympathetic nerve activity (MSNA, microneurography), forearm blood flow, and insulin sensitivity (total glucose uptake determined by an euglycemic/hyperinsulinemic clamp using stable isotope tracer infusion), and calculated forearm vascular resistance (FVR). Mean BP and HR were similar in both groups (86 ± 3 mm Hg and 61 ± 2 beats/min, and 85 ± 2 mm Hg and 62 ± 2 beats/min, respectively, in FH positive and negative respectively, P = ns). Baseline MSNA (24 ± 3 bursts/min in FH positive v 20 ± 3 bursts/min in FH negative, P = ns) and total glucose uptake [0.104 ± 0.014 mg/(kg × min × μU insulin/mL) in FH positive v 0.095 ± 0.014 mg/(kg × min × μU insulin/mL) in FH negative, P = ns] did not differ between the groups. Sympathetic and vascular responses to insulin were also similar in both groups. The increase in MSNA was 10 ± 2 bursts/min in FH positive and 10 ± 1 bursts/min in FH negative, P = ns. Thus, age- and weight-matched offspring with and without a FH of hypertension did not vary in MSNA or insulin sensitivity. These findings suggest that in the abscence of obesity and high arterial pressure, a FH of hypertension may not be accompanied by decreased insulin sensitivity or increased MSNA.     

Normalization of Insulin Resistance in Non-Obese Essential Hypertension by Cilazapril Treatment

To determine whether ACE inhibitor other than captopril improves insulin sensitivity in patients with essential hypertension, we measured insulin sensitivity to glucose utilization using SSPG method in 10 lean hypertensive subjects before and after chronic cilazapril treatment (1.5±0.2 mg/day, 15.6±2.1 weeks). The results were compared with those obtained in 10 healthy control subjects. SSPG obtained by insulin sensitivity test was significantly higher in hypertensive subjects, indicating a lower insulin sensitivity than in controls. After cilazapril treatment, SSPG reduced significantly to the level which was statistically not different from control subjects. Hyperinsulinemia diminished after treatment, while no significant change of blood glucose was observed during oral glucose tolerance test in hypertensive subjects. Plasma HDL cholesterol increased by cilazapril treatment. Cilazapril treatment has beneficial effect in the reversal of insulin resistance in patients with essential hypertension.     

Differential effects of ACE-inhibition and angiotensin II antagonism on fibrinolysis and insulin sensitivity in hypertensive postmenopausal women

The aim of this study was to compare the effects of trandolapril and losartan on plasminogen activator inhibitor type 1 (PAI-1) levels and insulin sensitivity in hypertensive postmenopausal women. We studied 89 hypertensive (diastolic blood pressure >90 and <110 mm Hg) postmenopausal women, aged 51 to 60 years not taking any hormone replacement therapy. Diabetic, obese, and smoking patients were excluded. After a 4-week placebo period, they were randomized to receive 2 mg of oral trandolapril (n = 45) or 50 mg of oral losartan (n = 44) for 12 weeks according to a double-blind, parallel group design. At the end of the placebo and active treatment periods, blood pressure (BP) was measured, plasma samples were drawn to evaluate PAI-1 antigen levels, and insulin sensitivity was assessed. Both trandolapril and losartan reduced systolic BP (by a mean of 16.9 mm Hg and 15.2 mm Hg, respectively, P < .01 v placebo) and diastolic BP (by a mean of 13.1 mm Hg and 11.9 mm Hg, respectively, P < .01 v placebo) with no difference between the two treatments. The PAI-1 antigen levels were significantly decreased by trandolapril (from 36.9 ± 21 ng/dL to 27.2 ± 17 ng/dL, P < .05), but not by losartan (from 35.3 ± 22 ng/dL to 37.1 ± 23 ng/dL, P = not significant). Glucose infusion rate was significantly increased by trandolapril (from 6.67 ± 0.56 mg/min/kg to 7.9 ± 0.65 mg/min/kg, P < .05), but was not significantly modified by losartan (from 6.7 ± 0.47 mg/min/kg to 6.9 ± 0.50 mg/min/kg, P = not significant). In the trandolapril group the PAI-1 decrease correlated with glucose infusion rate increase (r = 0. 36, P = .045) These results provide evidence of different effects of angiotensin converting enzyme inhibitors and AT₁ antagonists on fibrinolysis and suggest that the PAI-1 decrease induced by angiotensin converting enzyme inhibitors is related to their action on insulin sensitivity and is not dependent on angiotensin II antagonism but rather on other mechanisms. It remains to be seen whether these findings apply to other patient populations than postmenopausal women.     

实验性阻塞性肺气肿大鼠的凝血-纤溶系统失衡

目的:观察实验性阻塞性肺气肿大鼠的凝血纤溶系统失衡状态,并对其机制进行探讨。方法:Wistar大鼠24只,随机分为2组,正常对照组和模型组,每组12只。采用熏香烟加尾静脉注射内毒素的方法制备实验性阻塞性肺气肿大鼠模型。实验结束后,观察各组大鼠的病理及肺功能情况,用酶联免疫吸附法(ELISA)测定血浆组织型纤溶酶原激活剂(tPA)、纤溶酶原激活物抑制剂-1(PAI-1)、组织因子途径抑制物抗原(TFPI:Ag)的含量,发色底物法测定血浆抗凝血酶-Ⅲ(AT-Ⅲ)活性。结果:模型组大鼠肺功能指标第0·2s用力呼出容积占用力肺活量百分比(FEV0·2/FVC)(68·25±8·90)%,与正常对照组(88·52±2·09)%比较,差异有显著性(P<0·01);模型组大鼠AT-Ⅲ和TFPI分别为(56·04±14·81)%、(1·39±0·26)ng/mL,与正常对照组(85·46±18·03)%、(1·05±0·17)ng/mL比较,差异有显著性(P均<0·01);模型组大鼠tPA和PAI-1分别为(2·1±0·73)ng/mL、(0·54±0·07)ng/mL,与正常对照组(1·45±0·43)ng/mL、(0·80±0·24)ng/mL比较,差异有显著性(P均<0·05)。结论:模型组大鼠体内的凝血纤溶系统存在失衡状态,AT-Ⅲ、TFPI、tPA和PAI-1可能参与这一过程。     

脑梗死患者血浆组织型纤溶酶原激活物和抑制物活性的变化及意义

为了探讨动脉硬化性脑梗死患者急性期和恢复期的组织型纤溶酶原激活物及其抑制物活性的变化及其意义,采用发色底物法检测9例脑梗死患者和40例健康老年人的血浆组织型纤溶酶原激活物和抑制物1活性.对脑梗死患者的梗死体积和神经功能缺损进行了计算和评分,结果发现,脑梗死组急性期和恢复期的组织型纤溶酶原激活物活性分别为0.26±0.14和0.21±0.11 kIU/L,显著低于健康组(P<0.01);纤溶酶原激活物抑制物1活性分别为0.90±0.25和0.98±0.12 kAU/L,显著高于健康组(P<0.01);脑梗死体积为8.75±1.21 cm3;急性期神经功能缺损评分为18.56±3.62;组织型纤溶酶原激活物活性与脑梗死体积和神经功能缺损程度负相关(r=-0.5133,JP<0.05;r=-0.4914,P<0.05),纤溶酶原激活物抑制物1活性与脑梗死体积和神经功能缺损程度正相关(r=0.5621,P<0.05;r=0.5342,P<0.05)。结果提示,脑梗死患者急性和恢复期血浆纤溶活性显著降低,提示组织型纤溶酶原激活物与抑制物1在动脉硬化性脑梗死的病理过程中发挥了重要的作用。     

Increased PAI-1 and tPA antigen levels are reduced with metformin therapy in HIV-infected patients with fat redistribution and insulin resistance

Cardiovascular disease (CVD) risk associated with fat redistribution seen among HIV-infected individuals remains unknown, but may be increased due to hyperlipidemia, hyperinsulinemia, increased visceral adiposity, and a prothrombotic state associated with these metabolic abnormalities. In this study we characterized plasminogen activator inhibitor-1 (PAI-1) and tissue-type plasminogen activator (tPA) antigen levels, markers of fibrinolysis and increased CVD risk, in HIV lipodystrophic patients compared to controls. Furthermore, we investigated the effect of treatment with metformin on PAI-1 and tPA antigen levels in patients with HIV-associated fat redistribution. Eighty-six patients (age 43 +/- 1 yr, BMI 26.1 +/- 0.5 kg/m(2)) with HIV and fat redistribution were compared to 258 age- and BMI-matched subjects from the Framingham Offspring study. In addition, 25 HIV-infected patients with fat redistribution and fasting insulin >15 microU/mL [104 pmol/L] or impaired glucose tolerance, but without diabetes mellitus were enrolled in a placebo-controlled treatment study of metformin 500 mg twice daily. PAI-1 and tPA antigen levels were significantly increased in patients with HIV related fat redistribution compared to Framingham control subjects (46.1 +/- 4 vs 18.9 +/- 0.9 microg/L PAI-1, 16.6 +/- 0.8 vs. 8.0 +/- 0.3 microg/L tPA, P = 0.0001). Among patients with HIV infection, a multivariate regression analysis including age, sex, waist-to-hip ratio, BMI, smoking status, protease inhibitor use and insulin area under the curve (AUC), found gender and insulin AUC were significant predictors of tPA antigen. Twelve weeks of metformin treatment resulted in decreased tPA antigen levels (-1.9 +/- 1.4 vs +1.4 +/- 1.0 microg/L in the placebo-treated group P = 0.02). Similarly, metformin resulted in improvement in PAI-1 levels (-8.7 +/- 2.3 vs +1.7 +/- 2.9 microg/L, P = 0.03). Change in insulin AUC correlated significantly with change in tPA antigen (r = 0.43, P = 0.03). PAI-1 and tPA antigen, markers of impaired fibrinolysis and increased CVD risk, are increased in association with hyperinsulinemia in patients with HIV and fat redistribution. Metformin reduces PAI-1 and tPA antigen concentrations in these patients and may ultimately improve associated CVD risk.     

Functionally stable plasminogen activator inhibitor-1 in a family with cardiovascular disease and vitiligo

Vitiligo is a common skin condition with a complex pathophysiology characterized by the lack of pigmentation due to melanocyte degeneration. In this study, we investigated PAI-1 antigen (Ag) and activity levels in a 34 year old male with extensive vascular disease, alopecia areata and vitiligo. Fasting PAI-1 Ag and activity levels were measured at 9 a.m. in the subject and family members. Both PAI-1 Ag (67 ± 38 vs. 18.6 ± 6.5 ng/ml, P < 0.001) and specific activity (15.8 ± 10.0 vs. 7.6 ± 6.0 IU/pmol, P < 0.04) levels of PAI-1 were moderately elevated in subjects compared to the controls. PAI-1 kinetic studies demonstrated a markedly enhanced stability of plasma PAI-1 activity in the family members. Specific activity at 16 h was significantly higher than expected activity levels (0.078 ± 0.072 vs. 0.001 ± 0.001 IU/ng/ml, P < 0.001). While the exact mechanism of increased stability of PAI-1 activity in vitiligo is not known, it is likely due to post-translational modifications or increased binding affinity for a stabilizing cofactor. In conclusion, enhanced stability of PAI-1 may contribute to the pathophysiology of vascular disease and associated melanocyte degeneration. Systemic or local treatment with PAI-1 inhibitors may offer a potential treatment alternative to the near orphan status for vitiligo drug development.     

Plasma homocysteine concentrations and insulin sensitivity in hypertensive subjects

Hyperhomocysteinemia is associated with several cardiovascular disease risk factors including endothelial dysfunction and abnormalities of clotting functions, which are also common features of insulin resistance syndrome observed in hypertensive patients. Recent study has shown that acute hyperinsulinemia can lower plasma homocysteine concentrations in nondiabetic but not in type 2 diabetic individuals, indicating that insulin may regulate homocysteine metabolism. To investigate the relationships between plasma homocysteine concentration and insulin sensitivity, we studied 90 Chinese hypertensive patients and a group of control subjects (n = 86) matched for age, gender, and body mass index. Fasting plasma homocysteine levels, plasma lipoprotein concentrations, plasma glucose, and insulin responses to oral glucose tolerance tests (OGTT) were determined. The results showed that fasting plasma homocysteine concentrations were significantly higher in subjects with hypertension than in those with normotension (mean ± SEM, 8.1 ± 0.6 v 6.8 ± 0.2 μmol/L; P < .05). Fasting plasma homocysteine levels correlated significantly with insulin secretion in response to OGTT even after adjustment for body mass index (P < .05) in hypertensive patients but not in normotensive individuals. However, fasting plasma homocysteine concentrations showed no correlations with steady-state plasma glucose concentration, a measurement of insulin sensitivity, during an insulin suppression test in groups of hypertensive (n = 42) and normotensive (n = 37) subjects. When the steady-state plasma glucose concentrations were divided into three tertiles, fasting plasma homocysteine concentrations showed no difference across these three groups in either hypertensive patients (8.6 ± 0.5 v 7.2 ± 0.5 v 8.4 ± 0.6 μmol/L; P = .148) or normotensive subjects (6.3 ± 0.4 v 8.0 ± 0.8 v 7.0 ± 0.8 μmol/L; P = .199). In conclusion, hypertensive Chinese subjects had higher fasting plasma homocysteine concentrations and a higher degree of insulin resistance when compared to a group of age-, gender-, and body mass index-matched normotensive individuals. Fasting plasma homocysteine levels were associated with insulin response to OGTT in hypertensives but not in normotensives. No correlation was observed between the degree of insulin resistance and plasma homocysteine levels in either the hypertensive or the normotensive group. The role of insulin in homocysteine metabolism deserves further investigation.     

Protection by α2-macroglobulin of tissue plasminogen activator against inhibition by plasminogen activator inhibitor-1

Tissue plasminogen activator (tPA) is widely used in the treatment of acute myocardial infarction (MI). However, its thrombolytic efficacy does not correlate with the dose administered. The interactions between tPA, α2-macroglobulin (α2-M), and plasminogen activator inhibitor-1 (PAI-1) were investigated both in vitro and in patients undergoing tPA therapy for MI in an attempt to identify variables that might affect the clinical efficacy of tPA.
Purified α2-M (5.4 mg/ml) protected 16.0% or 22.4% of tPA (12.5 IU/ml) activity from inhibition by PAI-1 at 4 or 8 IU/ml in vitro . Of nine patients treated with 5–20 mega IU of tPA for MI, the plasma activity of tPA remained increased for 15–30 min after the cessation of infusion in eight; the patient who failed to exhibit a persistent increase in tPA activity had a low plasma concentration of α2-M. Total tPA activity, derived from the area under the activity-versus-time curve (AUC), showed a significant inverse correlation with the ratio of the plasma PAI-1 activity to the plasma α2-M concentration. Total tPA activity did not correlate with plasma PAI-1 activity or plasma α2-M concentration alone. Results suggest that α2-M, by binding to tPA, protects the latter against inhibition by PAI-1.     

Tissue plasminogen activator, fibrin D-dimer, and insulin resistance in the relatives of patients with premature coronary artery disease

Elevated levels of tissue-type plasminogen activator antigen (tPA), fibrinogen, and fibrin D-dimer predict coronary artery disease (CAD) events and stroke. These factors, possibly in association with insulin resistance, may be important in families in which CAD has become clinically apparent at a premature age. From 125 patients with angiographically confirmed, premature CAD, 175 healthy male relatives (age 相似文献   

Vascular cell adhesion molecule-1 as a biochemical marker of left ventricular mass in the patients with hypertension

Plasma levels of soluble intercellular adhesion molecule-1 (sICAM-1), vascular adhesion molecule-1 (sVCAM-1), and E-selectin were measured in 80 outpatients with uncomplicated essential hypertension. Although the levels of E-selectin and sICAM-1 were similar between the patients with and without left ventricular (LV) hypertrophy, sVCAM-1 level was significantly elevated in the patients with LV hypertrophy (759.7 ± 154.6 ng/mL v 984.4 ± 240.6 ng/mL, P < .0001). The LV mass normalized to body surface area or height were significantly correlated with sVCAM-1 (r = 0.615, P < .0001 and r = 0.571, P < .0001, respectively). These results indicate that a soluble adhesion molecule is correlated with LV mass in uncomplicated essential hypertensive patients.     

The relationship between renal cortical volume and predisposition to hypertension

It has been proposed that a reduction in the number of nephrons is a renal abnormality that plays an important role in the pathogenesis of essential hypertension. The objective of this study was to determine whether renal cortical volume, used as a measure of the number of nephrons, is lower in normotensive subjects with a familial predisposition to develop essential hypertension than in subjects who lack this predisposition. For this purpose, we measured renal cortical volume using electron beam computed tomography in 26 white offspring of two hypertensive parents (OHT; 14 women, 12 men) and 27 white offspring of two normotensive parents (ONT; 13 women, 14 men) who were stabilized on a high sodium diet for 3 days (200 mmol/day). In women, mean age was significantly greater in OHT than ONT (46.1 ± 4.9 [standard deviation] ν 41.8 ± 5.1 years, respectively, P = .04). In men, means for age and weight were greater in OHT than ONT (age: 47.1 ± 7.7 ν 37.9 ± 8.1 years, P < .01); weight: 90.2 ± 10.7 ν 81.1 ± 9.4 kg, P = .03) In women, mean total cortical volume did not differ significantly between OHT and ONT (156 ± 33.3 ν 166 ± 30.9 cc, P = .80). After adjustment for interindividual differences in age, mean total cortical volume remained not significantly different in OHT than ONT (160 ± 29.0 ν 162 ± 32.4 cc, P = .83). In men, mean total cortical volume was significantly greater in OHT than ONT (210 ± 33.6 ν 180 ± 20.0 cc, P < .01). After adjustment for interindividual differences in age, mean total cortical volume remained significantly greater in OHT than ONT (207 ± 33.2 ν 182 ± 19.8 cc, P = .02). After adjustment for interindividual differences in body weight, mean total cortical volume did not differ significantly between OHT and ONT (201 ± 21.7 ν 187 ± 20.1 cc, P = .09). The results of this study do not support the hypothesis that a decrease in number of nephrons, is a characteristic of white women or men with a familial predisposition to develop essential hypertension.     

Beneficial effect of a moderately energy-restricted diet on fibrinolytic factors in non-obese men

Impaired fibrinolytic activity has been reported in the elderly and is thought to play a role in the etiology of cardiovascular disease, one of the leading causes of death in most Western countries. Since restriction of energy intake has been demonstrated to act beneficially on the aging process in a variety of species, we studied the effect of a 10-week moderately energy-restricted (ER) regimen (80% of habitual) on plasminogen activator inhibitor (PAl) activity, PAl-1 antigen, tissue plasminogen activator (tPA) activity, and tPA antigen in non-obese, middle-aged men. Moreover, the relationship between these fibrinolytic markers and glucose tolerance was investigated. Weight loss in the ER group (n = 16) was considerable (−7.4 ± 1.7 kg, P < .001). Subjects in the control group (n = 8) also lost some weight (−2.1 ± 1.5 kg, P < .01). Fasting glucose levels decreased in the ER group (−0.31 ± 0.48 mmol/L, P < .05), which was correlated with the extent of weight loss (P < .01). Baseline insulin levels at 2 hours after an oral glucose load correlated with baseline PAl activity (P < .001) and PAl-1 antigen levels (P < .001). PAl activity decreased in the ER group (−2.94 ± 2.90 IU/mL, P < .001), particularly in subjects with a high baseline PAl activity (>9 IU/mL). Furthermore, energy restriction led to decreased PAl-1 antigen concentration (P < .05), a nonsignificant increase in tPA activity, and a decrease in tPA antigen concentration (P < .001). All these changes were more clear in subjects with a high baseline PAl activity: These results suggest that 10 weeks of moderate energy restriction has a profibrinolytic effect in non-obese, middle-aged men, at least in subjects with higher baseline PAl activity (>9 IU/mL). Moreover, in line with the suggestion that high PAl activity goes together with insulin resistance, a relationship between insulin concentration after a glucose load and PAl activity was found.     

高血压病并胰岛素抵抗患者单核细胞粘附功能的变化

观察高血压、胰岛素抵抗对单核细胞—血管内皮粘附功能的影响 ,采用改良的胰岛素抑制试验和单核细胞—血管内皮细胞粘附试验检测 33例高血压病患者和 32例正常对照者的胰岛素敏感性和单核细胞—血管内皮粘附功能。结果发现 ,高血压病患者单核细胞对内皮的粘附性显著高于正常对照者 (P <0 .0 1) ,且高血压患者稳态血糖浓度与单核细胞粘附数显著正相关 (r=0 .6 1,P <0 .0 0 1) ,正常对照者稳态血糖浓度与单核细胞粘附数也显著正相关 (r=0 .71,P <0 .0 0 1) ,而平均动脉压只有在两组合并分析时与单核细胞粘附数存在显著正相关关系 (r=0 .4 3,P <0 .0 0 1)。经多元回归分析发现 ,稳态血糖浓度及胰岛素浓度与单核细胞粘附数有独立的相关关系。结果提示 ,高血压、胰岛素抵抗使单核细胞对血管内皮的粘附性增强 ,这可能是高血压、胰岛素抵抗等代谢异常易发生动脉粥样硬化的机制之一。