Activity and cleavage site specificity of an anti-HIV-1 hairpin ribozyme in human T cells

The DD genotype is a polymorphism of the angiotensin-converting enzyme (ACE) gene, and is associated with a significantly increased risk of myocardial infarction. As endothelial dysfunction is an important event in both early atherogenesis and late atherosclerosis, we hypothesised that the adverse effect associated with the ACE/DD genotype might be mediated via endothelial damage. Using high resolution ultrasound, we studied the brachial arteries of 184 subjects aged 15-73 (mean 38 +/- 14) years, who were all normotensive, non-diabetic lifelong non-smokers. Arterial diameter was measured at rest, during reactive hyperaemia (with flow increase causing endothelium-dependent dilation) and after sublingual glyceryl trinitrate (GTN, an endothelium-independent vasodilator). The ACE genotype was determined in each case by DNA amplification; 49/184(27%) had DD, 89 (48%) had ID and 46 (25%) had II genotype. Flow-mediated dilation (FMD) was 8.5% +/- 3.9% in the DD, 7.8% +/- 4.1% in the ID and 7.8% +/- 4.1% in the II subjects (P = NS). GTN-induced dilation was also similar in the 3 groups. On multivariate analysis, endothelium-dependent dilation was inversely related to age (r = -0.33, P < 0.001), vessel size (r = -0.41, P < 0.001) but not ACE genotype (r = 0.002, P = 0.97). The ACE genotype is unrelated to endothelium-dependent dilation in the systemic arteries of clinically well adults. This suggests that the risk associated with this polymorphism may be mediated by other mechanisms.     

Evaluation of proteolytic activity of micro-organisms isolated from dry cured ham

BACKGROUND: Morphologic changes of the vascular endothelium are common in patients with systemic sclerosis and Raynaud's phenomenon. The aim of this study was to evaluate the endothelium-dependent vasodilatation and endothelium-independent vasodilatation and to examine the effects of short-term estrogen administration on vascular responses in these patients. METHODS AND RESULTS: The study included 12 female patients with systemic sclerosis and Raynaud's phenomenon (aged 49+/-14 years) and 12 age- and sex-matched healthy control subjects. With the use of high-resolution ultrasound imaging, brachial artery diameter was measured at rest, during reactive hyperemia (endothelium-dependent response), and after administration of sublingual nitroglycerin (endothelium-independent dilatation). Intima-media thickness of the common carotid artery was also measured. Baseline diameter was similar in patients and control subjects; intima-media thickness was significantly higher in patients (0.83+/-0.3 vs 0.46+/-0.2 mm, P= .002) than in control subjects. Flow-mediated dilatation was reduced in patients (3.6%+/-7% vs 11.9%+/- 4.6%, P = .003); endothelium-independent dilatation also was reduced in patients with Raynaud's phenomenon (14%+/-7% vs 23%+/-6%, P= .003). Vascular responses in 10 patients were examined 15 minutes after administration of conjugated estrogens (25 mg intravenously); there was a significant increase of endothelium-dependent dilatation after estrogen administration (1.7%+/-4% to 6.3%+/-4%, P= .01), whereas endothelium-independent dilatation did not change (13.4%+/-8% to 15.5%+/-7%, not significant). CONCLUSIONS: Endothelium-dependent vasodilatation and endothelium-independent vasodilatation are impaired in patients with Raynaud's phenomenon secondary to systemic sclerosis, whereas intima-media thickness is increased. Short-term estrogen administration can improve endothelial dysfunction in this group of patients.     

Mutations in fibroblast growth-factor receptor 3 in sporadic cases of achondroplasia occur exclusively on the paternally derived chromosome

OBJECTIVES: The aim of this study was to determine whether the combination of lipid-lowering therapy and vitamin E supplementation improves peripheral endothelial function and whether it is more effective than lipid-lowering therapy alone. BACKGROUND: Endothelium-dependent vasodilation is impaired in coronary and peripheral arteries of patients with hypercholesterolemia. Coronary endothelial function has been shown to improve under lipid-lowering and antioxidant therapy, but the effect of additive vitamin E supplementation in the brachial artery is unknown. METHODS: Seven patients with hypercholesterolemia (mean+/-SD; age 51+/-10 yr) were studied. Endothelium-dependent, flow-mediated dilation (FMD) and endothelium-independent nitroglycerin-induced dilation (NMD) were assessed in the brachial artery using high resolution ultrasound 1) at baseline (BL I), 2) after 8 weeks of simvastatin (20 mg) and vitamin E (300 IU) therapy (Comb I), 3) after withdrawal of vitamin E for 4 weeks (Statin), 4) after therapy as in #2 for 4 weeks (Comb II) and 5) after withdrawal of both drugs for 4 weeks (BL II). RESULTS: Combined simvastatin and vitamin E therapy reduced total cholesterol (Comb I vs. BL I: 276+/-22 vs. 190+/-14 mg/dl, p < 0.0001) and low-density lipoprotein (LDL)-C (197+/-22 vs. 106+/-22 mg/dl, p < 0.00001), augmented alpha tocopherol levels normalized to LDL (12.2+/-4.1 vs. 4.9+/-0.9 microg alpha-T/100 mg% LDL-C, p < 0.01) and resulted in significant improvements in FMD (16.4+/-4.7 vs. 4.9+/-2.5%, p < 0.001) as well as NMD (17.9+/-4.3 vs. 11.2+/-2.8%, p < 0.01). The ratio of FMD to NMD (0.92+/-0.17 vs. 0.46+/-0.24%, p < 0.05) also increased under combination therapy, indicating a greater improvement of FMD than that of NMD. After withdrawal of vitamin E, both FMD (Comb I vs. Statin: 16.4+/-4.7 vs. 7.9+/-4.7%, p < 0.01) and NMD (17.9+/-4.3 vs. 10.9+/-4.5%, p < 0.05) decreased significantly such that simvastatin alone only tended to improve FMD and did not change NMD. Results under combination therapy (Comb II vs. BL II) were reproducible. CONCLUSIONS: Combined vitamin E and simvastatin therapy leads to an improvement of FMD and NMD in the brachial artery of patients with hypercholesterolemia. The improvement of FMD is more pronounced after combination therapy than after lipid-lowering therapy alone, similar to previous findings in the coronary circulation.     

Cloning and expression of the major porin protein gene opcP of Burkholderia (formerly Pseudomonas) cepacia in Escherichia coli

OBJECTIVES: We sought to assess the effects of aging on the endothelial physiology of a group of Chinese adults. BACKGROUND: Several studies have documented an association between aging and progressive arterial endothelial dysfunction in white subjects. We hypothesized that age-related endothelial dysfunction, an important event in atherosclerosis, might be less marked in southern Chinese subjects, in whom the prevalence of coronary heart disease is only approximately 20% of that in industrialized countries. METHODS: We studied endothelial function in 76 healthy adults aged 16 to 70 years: 38 Chinese from a village of 3,000 people in southern China and 38 white subjects from Sydney, Australia. In each ethnic group, there were 19 younger persons (16 to 40 years) and 19 older adults (55 to 70 years). None had evidence of diabetes, hypertension or clinical vascular disease or had ever been regular cigarette smokers. With the use of high resolution external vascular ultrasound, brachial artery diameter was measured at rest, after flow increase (causing endothelium-dependent dilation) and after sublingual nitroglycerin (an endothelium-independent dilator). RESULTS: Endothelium-dependent dilation was similar in young Chinese (mean +/- SD 8.3 +/- 2.5%), young whites (7.9 +/- 2.0%) and older Chinese (6.8 +/- 2.9%), but it was significantly impaired in older whites (1.8 +/- 2.5%, p < 0.001 by analysis of variance). On multivariate analysis, older age was associated with impaired endothelium-dependent dilation (p < 0.001) (independent of the effects of serum cholesterol, gender and vessel size) in the white but not in the Chinese subjects (p = 0.83). Nitroglycerin-induced dilation was not significantly different with aging in either ethnic group. CONCLUSIONS: Endothelium-dependent dilation is similar in the arteries of healthy young Chinese and white adults. With older age, however, Chinese subjects are less susceptible to impaired endothelial function.     

Do parental convict cichlids of different sizes value the same brood number equally?

OBJECTIVES: We sought to determine endothelium-dependent vasodilator function in the brachial artery of patients with microvascular angina pectoris. BACKGROUND: Previous studies suggest the presence of endothelial dysfunction of the coronary microcirculation in patients with microvascular angina pectoris. It is not known whether endothelial dysfunction in these patients is a generalized process or whether it is confined to the coronary microcirculation only. METHODS: In 11 women (mean [+/-SD] age 60.1 +/- 7.8 years) with microvascular angina (anginal pain, normal epicardial coronary arteries, positive exercise stress test), endothelium-dependent vasodilation was assessed in the brachial artery by measuring the change in brachial artery diameter in response to hyperemic flow. Results were compared with 11 age- and gender-matched patients with known three-vessel coronary artery disease and 11 age- and gender-matched healthy control subjects. In all subjects, the intima-media thickness (IMT) of the common carotid artery was also measured. RESULTS: Flow-mediated dilation (FMD) was comparable in patients with microvascular angina and coronary artery disease (1.9 +/- 2.5% vs. 3.3 +/- 3.3%, p = NS) but was significantly lower in patients with microvascular angina than in healthy control subjects (1.9 +/- 2.5% vs. 7.9 +/- 3%, p < 0.05). IMT was significantly lower in patients with microvascular angina than in those with coronary artery disease (0.64 +/- 0.08 vs. 1.0 +/- 0.28 mm, p < 0.05) and was comparable between patients with microvascular angina pectoris and healthy control subjects (0.64 +/- 0.08 vs. 0.56 +/- 0.14 mm, p = NS). IMT > or = 0.8 mm was observed in 1 of 11 patients with microvascular angina, 1 of 11 control subjects and 10 of 11 patients with coronary artery disease. CONCLUSIONS: These findings suggest that endothelial dysfunction in microvascular angina is a generalized process that also involves the peripheral conduit arteries and is similar to that observed in atherosclerotic disease. IMT could be helpful in discriminating patients with microvascular angina and atherosclerotic coronary artery disease.     

Platelet cNOS activity is reduced in patients with IDDM and NIDDM

Several studies in vitro and in vivo suggest that the nitric oxide (NO) production is impaired in diabetes mellitus. Reduced levels of NO could contribute to vascular alteration facilitating platelet-vascular wall interaction, adhesion of monocytes to endothelium, vascular smooth muscle proliferation and by decreasing endothelium-dependent vasodilation. In this study we evaluated the activity of the constitutive nitric oxide synthase (cNOS) in platelets of patients with insulin-dependent diabetes mellitus (IDDM) and with non-insulin-dependent diabetes mellitus (NIDDM). When compared to that of normal subjects, cNOS activity is significantly lower in patients with IDDM and with NIDDM (1.57 +/- 0.25 vs. 0.66 +/- 0.10 fmol/min/10(9) PLTs and 1.57 +/- 0.25 vs. 0.67 +/- 0.08, respectively; p<0.005). These data demonstrate that the platelet cNOS activity is decreased in diabetes mellitus.     

Speech perception in children after cochlear implantation

Impaired endothelium-dependent vasodilation has been reported to play an important role in the pathogenesis of cardiovascular diseases such as coronary artery disease (CAD) and congestive heart failure (CHF). However, the precise mechanism of endothelial dysfunction has not been elucidated in these conditions. To evaluate the role of oxidative stress in endothelial dysfunction, the effect of antioxidant ascorbic acid on brachial flow-mediated, endothelium-dependent vasodilation during reactive hyperemia and nitroglycerin-induced endothelium-independent vasodilation was examined with high resolution ultrasound in 12 patients with CHF caused by idiopathic dilated cardiomyopathy without established coronary atherosclerosis and in 10 patients with CAD. Flow-mediated vasodilation in CHF (4.4+/-0.5%) and CAD (4.0 - 0.8%) was significantly (p <0.05) attenuated compared with that in 10 control subjects (9.6+/-0.9%). However, nitroglycerin-induced vasodilation was similar in 3 groups (13.7+/-1.3% in control, 13.9+/-1.1% in CHF, 12.7+/-1.4% in CAD). Ascorbic acid could significantly improve flow-mediated vasodilation only in patients with CAD (9.1+/-0.9%) but not with CHF (5.6+/-0.6%), and had no influence on nitroglycerin-induced vasodilation (13.6+/-1.1% in CHF, 14.0+/-1.3% in CAD). These results suggest that, in brachial circulation, augmented oxidative stress mainly leads to endothelial dysfunction in CAD but not in CHF caused by idiopathic dilated cardiomyopathy.     

Restoring vascular nitric oxide formation by L-arginine improves the symptoms of intermittent claudication in patients with peripheral arterial occlusive disease

BACKGROUND: Administration of L-arginine improves nitric oxide (NO) formation and endothelium-dependent vasodilation in atherosclerotic patients. OBJECTIVES: We investigated in this double-blind, controlled study whether prolonged intermittent infusion therapy with L-arginine improves the clinical symptoms of patients with intermittent claudication, as compared with the endothelium-independent vasodilator prostaglandin E1, and control patients. METHODS: Thirty-nine patients with intermittent claudication were randomly assigned to receive 2 x 8 g L-arginine/day, or 2 x 40 microg prostaglandin E1 (PGE1)/day or no hemodynamically active treatment, for 3 weeks. The pain-free and absolute walking distances were assessed on a walking treadmill at 3 km/h, 12% slope, and NO-mediated, flow-induced vasodilation of the femoral artery was assessed by ultrasonography at baseline, at 1, 2 and 3 weeks of therapy and 6 weeks after the end of treatment. Urinary nitrate and cyclic guanosine-3', 5'-monophosphate (GMP) were assessed as indices of endogenous NO production. RESULTS: L-Arginine improved the pain-free walking distance by 230+/-63% and the absolute walking distance by 155+/-48% (each p < 0.05). Prostaglandin E1 improved both parameters by 209+/-63% and 144+/-28%, respectively (each p < 0.05), whereas control patients experienced no significant change. L-Arginine therapy also improved endothelium-dependent vasodilation in the femoral artery, whereas PGE1 had no such effect. There was a significant linear correlation between the L-arginine/asymmetric dimethylarginine (ADMA) ratio and the pain-free walking distance at baseline (r=0.359, p < 0.03). L-Arginine treatment elevated the plasma L-arginine/ADMA ratio and increased urinary nitrate and cyclic GMP excretion rates, indicating normalized endogenous NO formation. Prostaglandin E1 therapy had no significant effect on any of these parameters. Symptom scores assessed on a visual analog scale increased from 3.51+/-0.18 to 83+/-0.4 (L-arginine) and 7.0+/-0.5 (PGE1; each p < 0.05), but did not significantly change in the control group (4.3+/-0.4). CONCLUSIONS: Restoring NO formation and endothelium-dependent vasodilation by L-arginine improves the clinical symptoms of intermittent claudication in patients with peripheral arterial occlusive disease.     

Endothelium-dependent dilatation is impaired in young healthy subjects with a family history of premature coronary disease

BACKGROUND: A family history of premature coronary artery disease (CAD) in a first-degree relative is an independent risk factor for coronary disease. Both genetic and environmental influences are likely to be responsible and may interact, but their relative importance is unclear. METHODS AND RESULTS: We studied endothelial function in 50 first-degree relatives (31 men, 19 women; mean age, 25+/-8 years) of patients (men < or = 45 years, women < or = 55 years) with proven CAD. All subjects were well, lifelong nonsmokers, not diabetic, and not hypertensive and took no medications. Using high-resolution external vascular ultrasound, we measured brachial artery diameter at rest and in response to reactive hyperemia (with increased flow causing an endothelium-dependent vasodilatation) and to sublingual glyceryltrinitrate (GTN, an endothelium-independent dilator). Vascular responses were compared with those of 50 healthy control subjects matched for age and sex. Flow-mediated dilatation (FMD) was impaired in the family history group (4.9+/-4.6% versus 8.3+/-3.5% in control subjects, P<.005). In contrast, GTN caused dilatation in all subjects (family history, 17.1+/-8.8%; control subjects, 19.0+/-6.3%; P=NS), suggesting that reduced FMD was due to endothelial dysfunction. When the family history subjects were subdivided, those found to have a serum cholesterol > 4.2 mmol/L (group A, n=10) had mildly impaired FMD compared with control subjects (5.5+/-5.1% versus 8.3+/-3.5%). In others whose affected relative had coronary risk factors (group B, n=24), FMD was also only slightly reduced (6.2+/-4.8% versus 8.3+/-3.5%). In contrast, subjects with no risk factors and whose affected relative had a normal cardiovascular risk factor profile (group C, n=16) had markedly impaired FMD (2.9+/-3.7% versus 8.3+/-3.5%). Although ANOVA of the three family history subgroups did not reach statistical significance (F=2.55, P=.09), pairwise analysis showed that FMD in group C was significantly impaired compared with group B (P=.026). CONCLUSIONS: Healthy young adults with a family history of premature coronary disease may have impaired endothelium-dependent dilatation, even in the absence of other cardiovascular risk factors. Those subjects, who were free of risk factors and whose affected first-degree relative was free of risk factors, had the most impaired endothelial function, suggesting a genetic influence on early arterial physiology that may be relevant to later clinical disease.     

EndothelinA receptor blockade improves nitric oxide-mediated vasodilation in monocrotaline-induced pulmonary hypertension

BACKGROUND: Nitric oxide (NO) and endothelin (ET) have been implicated in the pathogenesis of pulmonary hypertension (PH). Chronic ETA antagonist therapy reduces PH in monocrotaline (MCT)-treated rats. Interactions between the L-arginine-NO pathway and the ET system have been described. We therefore studied the effect of long-term treatment with an oral ETA antagonist (LU 135252) on NO-related vasodilation in isolated lungs from control rats and rats with MCT-induced PH. METHODS AND RESULTS: Three weeks after MCT injection, PH was associated with an increase in right ventricular pressure (from 27.4 +/- 0.9 to 66.6 +/- 4.1 mm Hg) and a decrease in endothelium-independent vasodilation in response to sodium nitroprusside (10(-10) to 10(-5) mol/L; delta Emax, from 11.1 +/- 0.9 to 2.7 +/- 0.3 mm Hg). Endothelium-dependent vasodilation in response to acetylcholine (10(-9) to 10(-4) mol/L) and the calcium ionophore A23187 (10(-9) to 10(-7) mol/L) remained unaffected. Treatment with LU 135252 did not significantly affect the endothelium-dependent and -independent vasodilations in control rats. However, in MCT-treated rats, LU 135252 therapy significantly reduced right ventricular pressure (39.7 +/- 2.1 mm Hg), potentiated acetylcholine-induced vasodilatation (delta Emax, from 1.6 +/- 0.2 to 3.7 +/- 0.4 mm Hg), and improved the responses to sodium nitroprusside (delta Emax, from 2.7 +/- 0.3 to 5.6 +/- 0.6 mm Hg). LU 135252 did not significantly alter the non-receptor-mediated endothelium-dependent vasodilation to A23187 or pulmonary constitutive NO synthase activity. CONCLUSIONS: MCT PH is associated with a reduced smooth muscle responsiveness to NO but a maintained endothelium-dependent vasodilatory potency. Long-term ETA antagonist therapy not only restores smooth muscle responsiveness to NO but also increases endothelium-dependent dilation in response to acetylcholine. This mechanism may contribute to the therapeutic benefit of ETA antagonists in PH.     

Regulation of the endogenous NO pathway by prolonged inhaled NO in rats

Nitric oxide (NO) modulates the endogenous NO-cGMP pathway. We determined whether prolonged inhaled NO downregulates the NO-cGMP pathway, which may explain clinically observed rebound pulmonary hypertension. Rats were placed in a normoxic (N; 21% O2) or hypoxic (H; 10% O2) environment with and without inhaled NO (20 parts/million) for 1 or 3 wk. Subsequently, nitric oxide synthase (NOS) and soluble guanylate cyclase (GC) activity and endothelial NOS (eNOS) protein levels were measured. Perfusate cGMP levels and endothelium-dependent and -independent vasodilation were determined in isolated lungs. eNOS protein levels and NOS activity were not altered by inhaled NO in N or H rats. GC activity was decreased by 60 +/- 10 and 55 +/- 11% in N and H rats, respectively, after 1 wk of inhaled NO but was not affected after 3 wk. Inhaled NO had no effect on perfusate cGMP in N lungs. Inhaled NO attenuated the increase in cGMP levels caused by 3 wk of H by 57 +/- 11%, but there was no rebound in cGMP after 24 h of recovery. Endothelium-dependent vasodilation was not altered, and endothelium-independent vasodilation was not altered (N) or slightly increased (H, 10 +/- 3%) by prolonged inhaled NO. In conclusion, inhaled NO did not alter the endogenous NO-cGMP pathway as determined by eNOS protein levels, NOS activity, or endothelium-dependent vasodilation under N and H conditions. GC activity was decreased after 1 wk; however, GC activity was not altered by 3 wk of inhaled NO and endothelium-independent vasodilation was not decreased.     

Immune response to glycated and oxidized LDL in IDDM patients with and without renal disease

OBJECTIVE: To study autoantibodies to oxidized and glycated LDL in IDDM patients with and without diabetic nephropathy and in nephropathy-related macroangiopathy RESEARCH DESIGN AND METHODS: The study included 101 IDDM patients with a long duration of diabetes and 54 healthy subjects. Patients were divided into two groups according to their median urinary albumin excretion rate (AER); the normoalbuminuric group had AER <20 microg/min and the albuminuric group >200 microg/min. The groups were matched for age and BMI, and the two diabetic groups were matched for duration of diabetes and glycemic control. Antibodies against oxidized LDL (using malondialdehyde-modified LDL as the antigen) and against glycated LDL were measured by enzyme-linked immunosorbent assay (ELISA). RESULTS: The mean antibody levels against glycated LDL were higher in IDDM patients (0.305 +/- 0.399) than in healthy subjects (0.166 +/- 0.22 optical density [OD]; P = 0.019), but levels did not differ significantly between normoalbuminuric and albuminuric IDDM patients (0.258 +/- 0.354 vs. 0.388 +/- 0.459, respectively). Among the three groups, antibody levels to oxidized LDL did not differ. IDDM patients showed an inverse correlation between antibodies to oxidized LDL and HbA1 (r = -0.211, P = 0.04). The antibody levels to glycated and oxidized LDL did not differ among albuminuric IDDM patients with or without clinical macroangiopathy. CONCLUSIONS: Antibodies to glycated and oxidized LDL do not seem to associate with diabetic nephropathy or nephropathy-related macroangiopathy.     

Proximal tubular basement membrane width in insulin-dependent diabetes mellitus

Although glomerular structure has been studied, careful evaluation of tubular basement membrane (TBM) structure in diabetes in humans has not been done. We measured proximal TBM width, glomerular basement membrane (GBM) width, mesangial fractional volume [Vv(Mes/glom)], mesangial matrix fractional volume [Vv(MM/glom)], and cortical interstitial fractional volume [Vv(Int/cortex)] in 35 insulin-dependent diabetic (IDDM) patients and 20 controls. The patients' mean age was 28 +/- 10 years (X +/- SD) and IDDM duration was 17 +/- 8 years. Twenty-five patients were normoalbuminuric, four microalbuminuric, and six had overt proteinuria. Tubular basement membrane and GBM widths were measured by the orthogonal intercept method and mesangial and interstitial parameters by point counting. The TBM width was 915 +/- 320 nm in IDDM patients and 558 +/- 116 nm in controls (P = 0.0005); the TBM width was also increased in normoalbuminuric patients (849 +/- 297 nm, P = 0.0005). The TBM width was strongly directly related to GBM width (r = 0.67, P < 0.001), Vv(Mes/glom) (r = 0.52, P < 0.01), and Vv(MM/glom) (r = 0.61, P < 0.001), but only weakly to Vv(Int/cortex) (r = 0.29, NS). The TBM width (r = 0.65, P < 0.001) and GBM width (r = 0.65, P < 0.001) were strongly related to hemoglobin A1C (HbA1C), while the Vv(Mes/glom) (r = 0.35, P < 0.05) and Vv(Int/cortex) (r = 0.30, NS) were only weakly related to HbA1C. Thus, increased proximal TBM width is an integral component of early nephropathology in IDDM patients. This study suggests that the metabolic disturbances of diabetes are strong determinants of the constellation of structural abnormalities occurring in human diabetic nephropathy.     

Lack of effect of captopril on glomerular hyperfiltration in normoalbuminuric normotensive insulin-dependent diabetic patients

The aim of the present study was to evaluate the effects of captopril on the glomerular filtration rate (GFR) and urinary albumin excretion rate (UAER) of normoalbuminuric normotensive insulin-dependent diabetes mellitus (IDDM) patients with and without glomerular hyperfiltration. Eleven normoalbuminuric (UAER < 30 micrograms/min) patients (age: 34.3 +/- 4.6 years: diabetes duration: 9.5 +/- 6.4 years) participated in the study. Six patients were considered to be hyperfiltering (GFR > or = 134 ml/min/ 1.73m2). GFR (51Cr-EDTA single injection technique), extracellular volume (ECV; distribution volume of 51Cr-EDTA), UAER (RIA) and metabolic and biochemical parameters were measured at baseline, after 6 weeks on captopril (25 mg p.o. twice daily) and after 6 weeks off captopril. Plasma renin activity (PRA; RIA), plasma aldosterone (RIA) and blood volume (51Cr red cell labeled) were measured at baseline and after 6 weeks on captopril. The baseline clinical and laboratory characteristics of hyperfiltering and normofiltering IDDM patients were similar. GFR did not change during the study (144.1 +/- 28.8; 139.7 +/- 21.8; 132.8 +/- 29.9 ml/min/1.73 m2) either in patients with hyperfiltration (164.6 +/- 20.7; 153.8 +/- 18.3; 148.6 +/- 31.0 ml/min/1.73 m2; n = 6) or without hyperfiltration (119.6 +/- 11.1; 123.2 +/- 11.9; 113.8 +/- 14.4 ml/min/1.73 m2; n = 5). Also, ECV (22.2 +/- 3.6; 21.5 +/- 4.3; 21.5 +/- 3.5 L/1.73 m2), UAER (3.9 [0.4-22.1]; 4.0 [0.2-11.4]; 3.7 [2.0-26.2] micrograms/min), systolic (112 +/- 13; 105 +/- 10; 111 +/- 11 mmHg) and diastolic (76 +/- 12; 72 +/- 9; 73 +/- 12 mmHg) blood pressure did not change. No difference in blood volume (60.8 +/- 10.4; 62.3 +/- 8.4 ml/kg) or plasma aldosterone (10.4 +/- 4.9; 7.7 +/- 3.8 ng/dl) was observed between baseline values and values after captopril use. PRA increased (2.4 [0.4-22.1]; 12.9 [2.2-41.1]ng/ml/h) at the end of 6 weeks on captopril (P = 0.002). Fasting plasma glucose, glycated hemoglobin, fructosamine, plasma cholesterol and potassium, 24 h urinary urea and sodium were similar during the study. These results were unchanged when patients with and without hyperfiltration were analyzed as separate groups. From baseline to the end of 6 weeks on captopril there was no correlation between change in GFR and change in glycated hemoglobin (r = 0.02, P = 0.96), systolic (r = 0.23; P = 0.49) and diastolic (r = -0.32, P = 0.32) blood pressure, urinary urea (r = 0.21; P = 0.53) and UAER (r = -0.16; P = 1.00). In conclusion, captopril has no effect on the GFR and UAER of normoalbuminuric normotensive IDDM patients irrespective of the presence of glomerular hyperfiltration.     

Interphase cytogenetics and competitive RT-PCR for residual disease monitoring in patients with chronic myeloid leukaemia during interferon-alpha therapy

OBJECTIVES: We sought to determine whether the antioxidant vitamin C improves endothelium-dependent vasodilation of forearm resistance vessels in patients with insulin-dependent diabetes mellitus. BACKGROUND: Endothelium-dependent vasodilation is impaired in patients with diabetes mellitus. Oxidatively mediated degradation of endothelium-derived nitric oxide contributes to abnormal endothelium-dependent vasodilation in animal models of diabetes mellitus. METHODS: The study group included 10 patients with insulin-dependent diabetes mellitus and 10 age-matched control subjects. Forearm blood flow was determined by venous occlusion plethysmography. Endothelium-dependent vasodilation was assessed by intraarterial infusion of methacholine (0.3 to 10 microg/min). Endothelium-independent vasodilation was assessed by intraarterial infusion of nitroprusside (0.3 to 10 microg/min). Forearm blood flow dose-response curves were determined for each drug infusion before and during concomitant infusion of vitamin C (24 mg/min). RESULTS: In diabetic subjects, endothelium-dependent vasodilation was augmented by the concomitant infusion of vitamin C (p = 0.001). Endothelium-independent vasodilation was not affected by the concomitant infusion of vitamin C (p = NS). In control subjects, vitamin C infusion did not affect endothelium-dependent vasodilation (p = NS). CONCLUSIONS: Vitamin C selectively restores the impaired endothelium-dependent vasodilation in the forearm resistance vessels of patients with insulin-dependent diabetes mellitus. These findings indicate that nitric oxide degradation by oxygen-derived free radicals contributes to abnormal vascular reactivity in humans with insulin-dependent diabetes mellitus.     

Macrophages during fibrosis following scleral fistulising surgery in a rat model

BACKGROUND: The vasodilator effects of angiotensin converting enzyme inhibitors have been ascribed to systemic inhibition of the angiotensin II generation. However, local mechanisms of vasodilation also have been suggested. We tested whether the angiotensin converting enzyme inhibitor enalaprilat mediated local vasodilation in human dorsal hand veins. METHODS: We infused enalaprilat and assessed changes in dorsal hand vein compliance using the linear variable differential transducer technique. Enalaprilat-mediated effects were assessed in small and large veins and in the presence and absence of one of two vasoconstrictors: exogenous norepinephrine or physiologic vasoconstriction by cooling. RESULTS: We infused locally in small dorsal hand veins at skin temperatures of less than 29.0 degrees C (baseline distention < 0.35 mm) in the absence of exogenous vasoconstrictors, enalaprilat mediated dose-dependent vasodilation (median effective dose [ED50], 12 ng/min to a maximal effect of 162% +/- 15% of baseline, p < 0.01). Maximal enalaprilat-mediated vasodilation was comparable to dilation mediated by insulin (175% +/-17% of baseline; p = 0.21) and less than dilation mediated by nitroglycerin (221% +/- 20% of baseline; p = 0.011). At skin temperatures > 31 degrees C, enalaprilat mediated dose-dependent vasodilation in small vessels only when vessels were preconstricted with norepinephrine (ED50 = 5.1 ng/min, maximal enalaprilat-mediated effect of 164% +/- 21% of baseline; p < 0.05). CONCLUSIONS: These data suggest enalaprilat mediates local vasodilation in dorsal hand veins, with an ED50 comparable to plasma enalaprilat concentrations achieved with oral enalapril therapy. This effect is dependent on vessel size and on the presence of preconstruction. Local vasodilator effects may be important in the clinical hemodynamic effects of angiotensin converting enzyme inhibitors.     

Sustained pulmonary vasodilation after inhaled nitric oxide for hypoxic pulmonary hypertension in swine

It has been shown that pulmonary vasodilation is sustained after discontinuation of inhaled nitric oxide (INO) during moderate hypoxic pulmonary hypertension (HPH) in swine. The present investigations demonstrated how INO dose, hypoxia duration, and endogenous NO production influence this important phenomenon. Fifteen adolescent Yorkshire swine were randomly assigned to three groups (n = 5 each) and underwent the following phasic experimental protocol: (I) Baseline ventilation (FIO2 = .3); (II) Initiating HPH (FIO2 = .16 to .18, PaO2 = 45 to 55 mm Hg); (III) INO at 10 ppm; (IV) Posttreatment observation; (V) INO of 80 ppm; and (VI) Posttreatment observation. Phase II (pretreatment hypoxia) lasted 30 minutes in group A (short hypoxia) and 120 minutes in group B (long hypoxia). N-nitro-L-arginine methyl ester (NAME) was used to inhibit nitric oxide synthase (NOS) throughout the experiment in group C (short hypoxia + NAME). Hemodynamics and blood gases were monitored by systemic and pulmonary artery catheters placed by femoral cutdown. Analysis of variance with post-hoc adjustment was used to compare groups at each phase, and the paired t test was used for comparisons within a group. With respect to baseline mean pulmonary artery pressure (MPAP) and pulmonary vascular resistance (PVR), there were no significant differences among the three groups. MPAP and PVR were significantly higher in group C than in group A during phase II, (MPAP, 76% +/- 8% v 33% +/- 2%; PVR, 197% +/- 19% v 78% +/- 10%; P < .05). There were no significant differences in MPAP or PVR during phases III through VI. When MPAP was expressed as percent dilation, 80 ppm caused significantly more dilation than did 10 ppm in all three groups. Groups A and C had significantly higher sustained pulmonary artery dilation after 80 ppm than after 10 ppm (A, 82% +/- 31% v 17% +/- 11%; C, 68% +/- 10% v 42% +/- 12%; both P < .05), but group B did not (43% +/- 15% v 30% +/- 9%; P = .25). High dose results in stronger vasodilation than low dose during and after INO for moderate HPH of short duration. Long hypoxia blunts this high-dose advantage. Endogenous NO inhibition augments HPH but does not decrease pulmonary vasodilation during or after INO.     

Impaired endothelium-dependent vasodilatation in women with previous gestational diabetes

OBJECTIVE: To assess whether otherwise healthy women with a history of gestational diabetes mellitus (GDM) may have abnormalities in endothelial function at a very early stage, before glucose intolerance occurs. RESEARCH DESIGN AND METHODS: A total of 33 women with previous GDM (17 nonobese [BMI < 27] and 16 obese [BMI > or = 27]) and 19 healthy nonobese women were examined. A 75-g oral glucose tolerance test was performed, and insulin levels and biochemical parameters were also measured. Using high-resolution ultrasound, we measured vasodilatory responses of the brachial artery during reactive hyperemia (endothelium-dependent vasodilatation), and after nitroglycerin administration, an endothelium-independent vasodilator. RESULTS: Flow-mediated dilatation (FMD) was significantly and equally decreased in both groups of women with previous GDM, compared with control subjects (1.6 +/- 3.7% in the nonobese GDM group and 1.6 +/- 2.5% in the obese GDM group vs. 10.3 +/- 4.4% in control subjects, P < 0.001). FMD correlated inversely with serum uric acid levels, BMI, serum total cholesterol, and basal insulin resistance (homeostasis model assessment). Nitrate-induced dilatation was significantly decreased only in the obese GDM group compared with control subjects, (21.4 +/- 5.1 vs. 27.9 +/- 9.5, P < 0.05). CONCLUSIONS: Endothelial dysfunction, which is considered as a very early index of atherogenesis, is already present in both obese and nonobese women with a history of GDM, even when they have normal glucose tolerance.     

An anatomic study of the superficial radial nerve and its clinical implications

BACKGROUND: Acetylcholine produces coronary artery (CA) constriction in diabetic patients, suggesting an impairment of endothelium-dependent dilation. In diabetes, multiple metabolic abnormalities may inactivate nitric oxide through oxygen free radical production. METHODS AND RESULTS: To examine the mechanism of this abnormal response, two physiological tests (ie, a cold pressor test [CPT] and coronary flow increase induced by an injection of 10 mg papaverine [PAP] in the distal left anterior descending CA) were performed before and after either intravenous L-arginine (625 mg/min x 10 minutes) or intravenous deferoxamine (50 mg/min x 10 minutes) in 22 normotensive nonsmoking diabetic patients with angiographically normal CAs and normal cholesterol. Coronary surface areas were measured with quantitative angiography. Before the administration of L-arginine or deferoxamine, CPT induced CA constriction in both groups (-14 +/- 10% and -15 +/- 11%, respectively; each P<.001), and PAP injection in distal LAD did not modify significantly proximal LAD dimensions. In the 10 diabetic patients receiving L-arginine, responses to CPT and PAP were not modified. Conversely, in the 12 patients receiving deferoxamine, CA dilated in response to the two tests (+10 +/- 9% after CPT and +22 +/- 7% after PAP, each P<.001). Intracoronary isosorbide dinitrate, an endothelium-independent dilator, produced similar dilation in the two groups (+47 +/- 19% and +41 +/- 15%, respectively; each P<.001). CONCLUSIONS: This study shows that (1) responses of angiographically normal CAs to CPT and to flow increase are impaired in diabetic patients; (2) abnormal responses are not improved by L-arginine, suggesting that a deficit in substrate for nitric oxide synthesis is not involved; and (3) deferoxamine restores a vasodilator response to the two tests, suggesting that inactivation of NO by oxygen species might be partly responsible for the impairment of CA dilation in diabetic patients.     

Morphological and functional changes in coronary vessel evoked by repeated endothelial injury in pigs

OBJECTIVE: We examined the morphological changes induced by repeated endothelial denudation in coronary artery (CA), as well as functional changes in the endothelium-dependent and smooth muscle responses to various vasoactive agents during the process of intimal thickening. METHODS: We observed vascular responses in denuded and non-denuded portions of pig CA while being fed a normal diet (n = 11, N group) or 2% cholesterol diet (n = 25, C group) to intracoronary acetylcholine (ACh), 5-hydroxytryptamine (5-HT), substance P (SP), and isosorbide dinitrate (ISDN) with and without the nitric oxide synthesis inhibitor N omega-nitro-L-arginine methyl ester (L-NAME, 10 mg/kg i.v.) over a period of 8 weeks. Balloon endothelial denudation of the left anterior descending CA was carried out every 2 weeks. RESULTS: In N group, maximum vasoconstriction was obtained with ACh 2 weeks after the first denudation [26 +/- 5% vs. 1 +/- 1% pre-denudation, p < 0.05]. L-NAME did not affect ACh-induced CA diameter changes. Thereafter, the response to ACh was attenuated by repeated denudation in N groups. However, the degree of 5-HT-induced CA narrowing at the denuded portion increased from 7 +/- 4% (0 week) to 88 +/- 8% (8 weeks) (p < 0.05). The changes resulted in severe myocardial ischaemia, and suggested that endothelium-dependent vasodilation was progressively attenuated while hyperreactivity of vascular smooth muscle simultaneously increased. Vasodilation induced by SP was attenuated somewhat, but ISDN-induced vasodilation was preserved. Although mild hypercholesterolaemia was induced in C group, the vascular responses to these vasoactive agents did not differ from those of N group. CONCLUSIONS: Repeated CA endothelial injury and regeneration induce the change of morphology and vascular reactivity in the denuded portion regardless of atherogenic diet. This study strongly suggests that intimal thickening caused by repeated endothelial injury and regeneration induces specific vascular responses to vasoactive agents. Moreover, it is also suggested that during the progression of intimal thickening, increased vascular smooth muscle contraction and decreased endothelium-dependent dilation appear in a stimulus-dependent manner, often leading to severe coronary vasoconstriction accompanied with definitive ECG ST change.