Vildagliptin and pioglitazone in patients with impaired glucose tolerance after kidney transplantation: a randomized, placebo-controlled clinical trial.

BACKGROUND: New-onset diabetes after transplantation (NODAT) is a serious complication after kidney transplantation affecting graft and patient survival. Currently, no guidelines exist for the management of renal transplant patients with impaired glucose tolerance (IGT), a risk factor for the development of NODAT and an independent predictor of death. METHODS: In a population of 48 stable renal transplant recipients at least 6 months from time of transplantation with newly diagnosed IGT, we tested the dipeptidylpeptidase-4 inhibitor vildagliptin, the thiazolidinedione pioglitazone, or placebo for 3 months in addition to lifestyle counseling. Outcome measures were difference in change in oral glucose tolerance test between the groups and between baseline and end of study as well as change in HbA1c, serum lipids, and renal and hepatic function. RESULTS: In both treatment groups, 2-hr plasma glucose at 3 months was significantly reduced compared with baseline (vildagliptin: -20±24 mg/dL; P=0.002 and pioglitazone: -23±29 mg/dL; P=0.004), and pioglitazone also significantly improved fasting plasma glucose (-11±14 mg/dL; P=0.003), although the primary outcome (difference in change in 2-hr plasma glucose among the three groups) did not reach statistical significance. Furthermore, HbA1c was decreased in both treatment arms (vildagliptin: -0.1%±0.3%; P=0.046 and pioglitazone: -0.2%±0.3%; P=0.029). In the placebo group, no significant changes in these parameters were observed. Only mild adverse events occurred and at a similar rate in all three groups. CONCLUSIONS: These data demonstrate that both vildagliptin and pioglitazone are of potential benefit in patients with IGT after renal transplantation in addition to lifestyle modification.

Early basal insulin therapy decreases new-onset diabetes after renal transplantation.

No effective interventions to reduce risk for new-onset diabetes after transplantation (NODAT), a condition associated with postoperative hyperglycemia and reduced patient and graft survival, have been established. In this 1-year, proof-of-concept clinical trial, we randomly assigned 50 renal transplant recipients to immediate-postoperative isophane insulin for evening blood glucose ≥140 mg/dl (treatment group) or short-acting insulin and/or oral antidiabetic agents for blood glucose ≥180-250 mg/dl (standard-of-care control group). We included only patients without a history of diabetes who received tacrolimus. By the third postoperative evening, all patients in the treatment group had blood glucose ≥140 mg/dl and were subsequently treated with basal insulin; during the first 3 weeks after transplantation, the mean ± SD daily insulin dosage was 17±11 IU/d. Among controls, 23 (92%) of 25 had blood glucose ≥200 mg/dl and 18 (72%) of 25 received standard-of-care antihyperglycemic treatment. Asymptomatic hypoglycemia occurred five times in the treatment group and once in the control group. Throughout follow-up, the treatment group had 73% lower odds of NODAT (odds ratio, 0.27) than the control group, and hemoglobin A1c was on average 0.38% lower in the treatment group than the control group. Twelve months after transplantation, all patients in the treatment group were insulin-independent, whereas 7 (28%) of 25 controls required antidiabetic agents. The groups did not differ for insulin sensitivity, but the treatment group showed better ß-cell function throughout the 1-year follow-up. In conclusion, this study suggests regimens that include basal insulin significantly reduce the odds for NODAT after renal transplantation, presumably via insulin-mediated protection of ß cells.

Actovegin®: a biological drug for more than 5 decades.

Actovegin(®) is a biological drug manufactured from a natural source: it is a calf blood hemodialysate. Its therapeutic benefits stem from a variety of pharmacodynamic actions that can be summarized to a common goal, i.e. the enhancement of cellular metabolism; this results from an insulin-like activity mediated by Inositol-phospho-oligosaccharides. Actovegin(®) results in beneficial effects in several pathophysiological clinical settings including malfunction of the blood circulation and trophic disturbances in the brain, impairment of peripheral blood circulation and associated diseases, dermal transplants and acute and chronic wounds. Here, we give an overview of the pharmacodynamic actions of calf-blood hemidialysate and its beneficial effects in a variety of clinical settings.

A randomized, placebo-controlled, double-blind, prospective trial to evaluate the effect of vildagliptin in new-onset diabetes mellitus after kidney transplantation.

BACKGROUND: New-onset diabetes mellitus after transplantation (NODAT), a frequent and serious complication after transplantation, is associated with decreased graft and patient survival. Currently, it is diagnosed and treated primarily according to existing guidelines for type II diabetes. To date, only a few trials have studied antidiabetic drugs in patients with NODAT. Vildagliptin is a novel dipeptidyl peptidase-4 (DPP-4) inhibitor that improves pancreatic islet function by enhancing both α- and ß-cell responsiveness to increased blood glucose. Experimental data show potential protective effects of DPP-4 inhibitors on islet function after exogenous stress stimuli including immunosuppressants. Therefore, the therapy of NODAT with this class of compounds seems attractive. At present, vildagliptin is used to treat type II diabetes as monotherapy or in combination with other antidiabetic drugs, since that it efficiently decreases glycated hemoglobin (HbA1c) values. Additionally, vildagliptin has been shown to be safe in patients with moderately impaired kidney function. This study will evaluate the safety and efficacy of vildagliptin monotherapy in renal transplant recipients with recently diagnosed NODAT. METHODS/DESIGN: This study is a randomized, placebo-controlled, double-blind, prospective phase II trial. Using the results of routinely performed oral glucose tolerance tests (OGTT) in stable renal transplant patients at our center, we will recruit patients without a history of diabetes and a 2 h glucose value surpassing 200 mg/dl (11.1 mmol/l). They are randomized to receive either 50 mg vildagliptin or placebo once daily. A total of 32 patients with newly diagnosed NODAT will be included. The primary endpoint is the difference in the 2 h glucose value between baseline and the repeated OGTT performed 3 months after treatment start, compared between the vildagliptin- and the placebo-group. Secondary endpoints include changes in HbA1c and fasting plasma glucose (FPG). The safety of vildagliptin in renal transplant patients will be assessed by the number of symptomatic hypoglycemic episodes (glucose <72 mg/dl or 4 mmol/l), the number of adverse events, and possible medication-associated side-effects. DISCUSSION: NODAT is a severe complication after kidney transplantation. Few trials have assessed the safety and efficacy of antidiabetic drugs for these patients. The purpose of this study is to assess the safety and efficacy of vildagliptin in renal transplant patients with NODAT. TRIAL REGISTRATION: ClinicalTrials.gov NCT00980356.

Treatment with alpha-lipoic acid reduces asymmetric dimethylarginine in patients with type 2 diabetes mellitus.

Elevated asymmetric dimethylarginine (ADMA) concentrations predict cardiovascular events in patients with type 2 diabetes mellitus (T2DM). It has been shown that alpha-lipoic acid (ALA) improves endothelial function and oxidative stress in these patients. The present study investigated if ALA reduces ADMA in patients with T2DM. Plasma concentrations of ADMA, L-arginine and symmetric dimethylarginine (SDMA) were determined in a double-blind, randomized, placebo-controlled study in patients with T2DM. Intravenous ALA (n = 16) or placebo (n = 14) was administered daily for 3 weeks. ALA reduced ADMA while no change was observed with placebo (mean change -0.05 micromol/1[95% CI: -0.01; -0.09] vs. 0.01 micromol/1 [95% CI: -0.05; -0.03]; ANOVA p = 0.031). SDMA and L-arginine were not affected by ALA. In conclusion ALA treatment reduces ADMA in patients with T2DM. Long-term studies need to demonstrate if ALA may cause cardiovascular risk reduction.

[Drug interactions in geriatric medicine]. / Medikamenteninteraktionen in der Geriatrie.

Drug interactions are often seen in elder patients due to polymedication. They can lead to unwanted side effects attended with unspecific symptoms such as vertigo, lateropulsion, fatigue or confusion. This can result in a prescribing cascade. Interactions can take place on all pharmacodynamic and pharmacokinetic levels, whereas the CYP enzyme-dependent metabolism seems to play a key role. The incidence of drug interactions is quite high and clinical relevant interactions are also not uncommon. Especially drugs with a low therapeutic index are more likely to be the target of clinical relevant interactions. However, most of the drug interactions can be managed by dose-reduction or by replacing one of the possibly interacting drugs. An important point is to remember the possibility of drug interactions.

Minimal local anesthetic volume for peripheral nerve block: a new ultrasound-guided, nerve dimension-based method.

BACKGROUND AND OBJECTIVES: Nerve blocks using local anesthetics are widely used. High volumes are usually injected, which may predispose patients to associated adverse events. Introduction of ultrasound guidance facilitates the reduction of volume, but the minimal effective volume is unknown. In this study, we estimated the 50% effective dose (ED50) and 95% effective dose (ED95) volume of 1% mepivacaine relative to the cross-sectional area of the nerve for an adequate sensory block. METHODS: To reduce the number of healthy volunteers, we used a volume reduction protocol using the up-and-down procedure according to the Dixon average method. The ulnar nerve was scanned at the proximal forearm, and the cross-sectional area was measured by ultrasound. In the first volunteer, a volume of 0.4 mL/mm of nerve cross-sectional area was injected under ultrasound guidance in close proximity to and around the nerve using a multiple injection technique. The volume in the next volunteer was reduced by 0.04 mL/mm in case of complete blockade and augmented by the same amount in case of incomplete sensory blockade within 20 mins. After 3 up-and-down cycles, ED50 and ED95 were estimated. Volunteers and physicians performing the block were blinded to the volume used. RESULTS: A total 17 of volunteers were investigated. The ED50 volume was 0.08 mL/mm (SD, 0.01 mL/mm), and the ED95 volume was 0.11 mL/mm (SD, 0.03 mL/mm). The mean cross-sectional area of the nerves was 6.2 mm (1.0 mm). CONCLUSIONS: Based on the ultrasound measured cross-sectional area and using ultrasound guidance, a mean volume of 0.7 mL represents the ED95 dose of 1% mepivacaine to block the ulnar nerve at the proximal forearm.

Intra-arterial vitamin C prevents endothelial dysfunction caused by ischemia-reperfusion.

OBJECTIVE: Ischemia-reperfusion (IR) injury causes tissue injury and endothelial dysfunction. There is evidence that oxidative stress plays an important role. METHODS: We tested if IR-induced endothelial dysfunction could be prevented by administration of the antioxidant vitamin C. Twenty-six healthy male subjects and eight male patients with peripheral arterial disease (PAD) were enrolled in this randomised placebo-controlled study. Forearm blood flow (FBF) measurements in response to the vasodilators acetylcholine (ACh; endothelium-dependent agonist) or nitroglycerin (NTG; endothelium-independent) were performed before and after forearm ischemia for 20 min. FBF responses were reassessed during reperfusion with intra-arterial co-administration of 24 mg/min vitamin C or placebo. In six volunteers responses to the NO-synthase inhibitor N-monomethyl-L-arginine (L-NMMA) were also assessed before and after ischemia with and without vitamin C. RESULTS: ACh-induced vasodilation was blunted in subjects receiving placebo after reperfusion (p<0.05 versus baseline). Administration of vitamin C completely prevented impaired responsiveness. NTG-induced vasodilation was not affected by reperfusion or vitamin C. This finding was consistent in patients with PAD and impaired endothelial function, where local vitamin C infusion restored FBF reactivity to ACh before and after IR injury (p<0.05 versus baseline). Again, NTG-induced vasodilation was not affected. Blunted L-NMMA responses seen during reperfusion could be completely reversed by vitamin C. CONCLUSIONS: Our data indicate that IR-induced vascular injury can be prevented by administration of antioxidants.

Impaired vascular nitric oxide bioactivity in women with previous gestational diabetes.

BACKGROUND: Dysfunction of the vascular endothelium, preceding vascular morbidity and type 2 diabetes, is present in women with previous gestational diabetes (GDM). However, it is unknown whether excess weight, insulin resistance, and asymmetric dimethylarginine (ADMA)--an endogenous nitric oxide (NO) synthase inhibitor--also contribute to the vascular changes observed in these patients. The aim of this study was therefore to identify factors other than GDM that impair vascular function. METHODS: Seven overweight and five non-overweight women with previous GDM were included in this study. Vascular function was assessed from forearm blood-flow responses to the endothelium-dependent vasodilator acetylcholine (ACh), the endothelium-independent vasodilator glyceryltrinitrate, the vasoconstrictor norepinephrine and the NO synthase inhibitor N(G)-monomethyl-L-arginine (L-NMMA). ADMA was measured in venous blood, and insulin resistance was estimated from a modified intravenous glucose tolerance test. Twenty healthy male volunteers served as a historical control group. RESULTS: Vasodilation of forearm resistance vessels in response to ACh was impaired in overweight women when compared with non-overweight women (P < 0.05); similarly, vasoconstrictor reactivity tended to be smaller in the overweight group. In addition, there was a significant relationship between vascular responsiveness to ACh and L-NMMA, body-mass index, serum ADMA concentrations and stimulated glucose levels (all P < 0.05). ACh responses and ADMA levels in non-overweight women were similar to those of healthy controls. CONCLUSION: Factors such as obesity, increased ADMA levels and insulin resistance appear to be strong contributors to endothelial dysfunction observed in women with GDM.

Effects of N-acetylcysteine against systemic and renal hemodynamic effects of endotoxin in healthy humans.

OBJECTIVE: Systemic inflammation causes vasodilation and impairs the vascular response to catecholamines. There is evidence that altered vasoreactivity is associated with increased production of free radicals. We studied the influence of systemic doses of the antioxidant N-acetylcysteine on inflammatory cytokines and renal plasma flow and on the systemic pressor response to norepinephrine during experimental endotoxemia. DESIGN: A double-blind, placebo-controlled crossover study. SETTING: Medical University of Vienna, Clinical Pharmacology, Vienna General Hospital, AKH. SUBJECTS: Eight healthy, male humans. INTERVENTIONS: Intravenous administration of Escherichia coli endotoxin (lipopolysaccharide, 20 IU/kg) on two separate study days with concomitant intravenous infusion of placebo or N-acetylcysteine (150 mg/kg loading dose; 15 mg/kg/hr continuous infusion), respectively. MEASUREMENTS AND MAIN RESULTS: Measurements of inflammatory cytokines, of renal plasma flow by the para-aminohippurate-clearance method, and of the systemic pressor response to norepinephrine were taken at baseline and after endotoxin. Lipopolysaccharide increased body temperature and plasma concentrations of tumor necrosis factor-alpha, which was mitigated during N-acetylcysteine infusions. Likewise, the lipopolysaccharide-induced increases in renal plasma flow and decreases in blood pressure were attenuated, and the hyporeactivity of pulse rate to norepinephrine 4 hrs after lipopolysaccharide was improved by N-acetylcysteine. CONCLUSION: High doses of N-acetylcysteine might exert protective effects on systemic hemodynamics and on the reactivity to catecholamines in humans challenged by lipopolysaccharide. This action of the antioxidant N-acetylcysteine is paralleled by humoral anti-inflammatory mechanisms and may be useful in patients with systemic inflammation.

Rosiglitazone prevents free fatty acid-induced vascular endothelial dysfunction.

CONTEXT: Free fatty acids (FFAs) cause insulin resistance and vascular endothelial dysfunction. The peroxisome proliferator-activated receptor gamma agonist rosiglitazone acts as insulin sensitizer and could exert vasoprotective properties by preservation of endothelium-dependent vasodilation. OBJECTIVE: We tested the effect of rosiglitazone on FFA-induced endothelial dysfunction of the forearm resistance vessels, insulin sensitivity, asymmetric dimethylarginine (ADMA), and high-sensitivity C-reactive protein concentrations in humans. DESIGN AND SETTING: We conducted a double-blind, randomized, placebo-controlled parallel-group study at a university hospital. PATIENTS AND INTERVENTIONS: Rosiglitazone 8 mg daily or placebo was administered to 16 healthy male subjects for 21 d. On the last day, triglycerides and heparin were infused iv to increase FFA plasma concentrations. MAIN OUTCOME MEASURES: Forearm blood flow responses to the endothelium-dependent vasodilator acetylcholine and the endothelium-independent vasodilator nitroglycerine were assessed using strain-gauge plethysmography at baseline, and on d 21 before and after 5 h of triglyceride/heparin infusion. RESULTS: Forearm blood flow reactivity was not affected by rosiglitazone or placebo. Infusion of triglyceride/heparin substantially increased FFA concentrations (P < 0.001) and reduced endothelium-dependent vasodilation by 38 +/- 17% (P = 0.024). In the face of lower FFA elevation (P = 0.047 vs. controls), endothelium-dependent vasodilation was preserved in subjects receiving rosiglitazone (P = 0.016 vs. placebo). Endothelium-independent vasodilation and C-reactive protein were unchanged, whereas insulin sensitivity and plasma ADMA similarly decreased in both study groups after FFA elevation (both P < 0.05 vs. baseline). CONCLUSIONS: Rosiglitazone mitigates the increase in FFA after infusion of triglyceride/heparin and prevents FFA-induced endothelial dysfunction. These effects are independent and possibly occur before any changes in insulin sensitivity and ADMA plasma concentrations in healthy subjects.

Exercise training lowers plasma visfatin concentrations in patients with type 1 diabetes.

CONTEXT: Exercise training exerts beneficial effects on metabolic and vascular risk factors in patients with type 1 diabetes mellitus (T1DM). It is unknown whether training also influences concentrations of visfatin, a novel insulin-mimetic adipocytokine. OBJECTIVES: In this study, we have investigated whether plasma visfatin concentrations are altered by training in patients with T1DM. DESIGN AND PATIENTS: Fasting plasma visfatin concentrations and metabolic parameters were measured in 18 patients with T1DM who participated in a supervised aerobic exercise program for 4 months. Three subjects discontinued training prematurely after 2 months. Samples were obtained before and during training and 8 months after the end of regular exercise. Fourteen healthy young subjects served as controls. RESULTS: At baseline, patients with T1DM had higher visfatin concentrations than controls (64.1 +/- 12.0 vs. 1.3 +/- 0.0 ng/ml, P < 0.01). Exercise reduced visfatin after 2 and 4 months to 27.8 +/- 2.6 (n = 18) and 17.5 +/- 3.4 ng/ml (n = 15), respectively (P < 0.001 for n = 15 subjects who participated in all visits, ANOVA). This effect was maintained 8 months after cessation of training, with visfatin concentrations of 19.7 +/- 5.0 ng/ml (n = 15). Metabolic parameters were not affected by the training program. CONCLUSION: Elevated visfatin concentrations in patients with T1DM can be lowered by regular physical exercise. It is unknown whether glucose tolerance is affected by changes in visfatin concentrations.

Simvastatin suppresses endotoxin-induced upregulation of toll-like receptors 4 and 2 in vivo.

In addition to lipid lowering effects, statins appear to have pleiotropic immunomodulatory properties. As they particularly affect monocyte functions, we tested the influence of statin treatment on the monocyte activating toll-like receptors (TLR) 4 and 2 in response to lipopolysaccharides (LPS) in vivo. In this double-blind, placebo-controlled study, 20 healthy, male subjects were randomized to receive either simvastatin (80 mg/day) or placebo for 4 days before intravenous LPS administration (20 IU/kg). Simvastatin did not influence the increase in TLR transcripts after LPS administration measured in mRNA isolated from whole blood by quantitative RT-PCR. In contrast, the parallel upregulation of TLR4 and TLR2 on the surface of monocytes determined by flow cytometry was attenuated by more than half after LPS challenge (P<0.02). Suppressed TLR4 and TLR2 expression was associated with diminished circulating concentrations of tumor necrosis factor-alpha and monocyte chemoattractant protein-1. In conclusion, high-dose simvastatin pretreatment blunted TLR4 and TLR2 expression on monocytes in a human endotoxemia model on a posttranscriptional level. This suppressive effect of statins on key receptors of the innate immunity which was associated with a reduction of effector cytokines reveals a potential mechanism for their beneficial effects in sepsis and cardiovascular disease.

Exercise training improves low-density lipoprotein oxidability in untrained subjects with coronary artery disease.

UNLABELLED: Exercise training improves low-density lipoprotein oxidability in untrained subjects with coronary artery disease. OBJECTIVE: To test the hypothesis that regular exercise alters low-density lipoprotein (LDL) oxidability in patients with coronary artery disease. DESIGN: Longitudinal study. SETTING: General hospital and community. PARTICIPANTS: Thirteen patients. INTERVENTIONS: Training program comprising running bouts twice weekly over 2 months. MAIN OUTCOME MEASURES: Plasma lipid profile, oxidized LDL, and rate (Ox(rate)) and amount (Ox(amount)) of LDL reaction products were measured at baseline and after 2 months of training. Brachial artery endothelium-dependent and -independent vasodilation was assessed by use of ultrasound. RESULTS: Lipid profile and oxidized LDL remained unchanged, but mean Ox(rate) and Ox(amount) +/- standard deviation were reduced from 2.5+/-1.5nmol.mgLDL(-1).min(-1) and 120.3+/-75.3nmol/mgLDL at baseline to 0.4+/-0.2nmol.mgLDL(-1).min(-1) and 21.3+/-11.4nmol/mgLDL after training (P<.05), respectively. Brachial artery vasodilation was suggested to be improved, but statistical significance was not reached in the small cohort under study. CONCLUSIONS: Aerobic training enhances the resistance of LDL to oxidation in patients with coronary artery disease, which may play a role in the favorable effects of exercise.

Vasoconstrictor hyporeactivity can be reversed by antioxidants in patients with advanced alcoholic cirrhosis of the liver and ascites.

OBJECTIVE: Hyperdynamic circulation and systemic vasodilation complicate cirrhosis of the liver and are related to vasoconstrictor hyporeactivity. We investigated whether impaired vasoconstrictor responsiveness may be overcome by antioxidants in patients with decompensated alcoholic cirrhosis. DESIGN: Controlled clinical study. SETTING: University setting. PATIENTS: Nine patients with liver cirrhosis Child-Pugh grade C and nine healthy age-matched volunteers. INTERVENTIONS: Forearm blood flow responses to intra-arterial norepinephrine, angiotensin II, and the nitric oxide synthase inhibitor N-monomethyl-l-arginine were measured by strain-gauge plethysmography and compared between groups of patients. To assess the role of oxidative stress, the antioxidant vitamin C (24 mg/min) was administered locally into the brachial artery, and forearm blood flow responses were reassessed. MEASUREMENTS AND MAIN RESULTS: Plasma concentrations of vitamin C were lower in patients with cirrhosis (p < .05). In patients with cirrhosis, the reactivity to norepinephrine and angiotensin II was markedly reduced (p < .05 vs. controls). Coadministration of vitamin C completely restored the potency of vasoconstrictors to that in controls but had no effect in healthy subjects. No changes were observed in time-control experiments in cirrhosis patients (n = 3) employing vehicle coinfusion. The response to N-monomethyl-L-arginine was comparable between groups and not affected by vitamin C. CONCLUSIONS: Oxidative stress with consumption of antioxidants seems to play an important role in the development of vasoconstrictor hyporeactivity in patients with cirrhosis. Antioxidant therapy may be a promising clinical approach to restore vasoconstrictor hyporeactivity in these patients.

Endurance training increases the number of endothelial progenitor cells in patients with cardiovascular risk and coronary artery disease.

OBJECTIVE: As regular physical exercise improves endothelial dysfunction and promotes cardiovascular health, we investigated the effect of training on angiogenesis by measuring the number of circulating endothelial progenitor cells (EPC), the level of EPC-mobilizing growth factors and tested vascular function by flow-mediated dilation (FMD) in patients with coronary artery disease (CAD) and cardiovascular risk factors (CVRF). In addition, degradation products of the NO pathway (NOx) were determined. METHODS AND RESULTS: Twenty patients with documented CAD and/or CVRF joined a 12-week supervised running training. Circulating EPCs--defined by the surface markers CD34, KDR and CD133--were measured at baseline and after exercise training by flow cytometry. We found a significant increase in circulating EPCs (2.9+/-0.4-fold increase; P < .0001), which was positively correlated with both, the change of FMD (r = .81, P < .001) and the increase of NOx synthesis (r = .83, P < .001). Plasma VEGF and erythropoietin did not change in response to exercise. However, we observed a positive correlation between the number of EPCs and erythropoietin at baseline (r = .70, P < .01) and after training (r = .73, P < .01). CONCLUSIONS: Regular exercise training augments the number of circulating EPCs in patients with CVRF and CAD and is associated with improved vascular function and NO synthesis.

Tetrahydrobiopterin corrects Escherichia coli endotoxin-induced endothelial dysfunction.

Acute inflammation causes endothelial dysfunction, which is partly mediated by oxidant stress and inactivation of nitric oxide. The contribution of depletion of tetrahydrobiopterin (BH(4)), the cofactor required for nitric oxide generation, is unclear. In this randomized, double-blind, three-way crossover study, forearm blood flow (FBF) responses to ACh and glyceryltrinitrate (GTN) were measured before and 3.5 h after infusion of Escherichia coli endotoxin (LPS, 20 IU/kg iv) in eight healthy men. The effect of intra-arterial BH(4) (500 microg/min), placebo, or vitamin C (24 mg/min) was studied on separate days 3.5 h after LPS infusion. In addition, human umbilical vein endothelial cells were incubated for 24 h with vitamin C and LPS. ACh and GTN caused dose-dependent forearm vasodilation. The FBF response to ACh, which was decreased by 23 +/- 17% (P < 0.05) by LPS infusion, was restored to baseline reactivity by BH(4) and vitamin C. FBF responses to GTN were not affected by BH(4) or vitamin C. LPS increased leukocyte count, high-sensitivity C-reactive protein, IL-6, IL-1beta, IFN-gamma, monocyte chemoattractant protein-1, pulse rate, and body temperature and decreased platelet count and vitamin C concentration. Vitamin C increased forearm plasma concentration of BH(4) by 32% (P < 0.02). Incubation with LPS and vitamin C, but not LPS alone, increased intracellular BH(4) concentration in human umbilical vein endothelial cells. Impaired endothelial function during acute inflammation can be restored by BH(4) or vitamin C. Vitamin C may exert some of its salutary effects by increasing BH(4) concentration.

Simvastatin blunts endotoxin-induced tissue factor in vivo.

BACKGROUND: Beyond lipid lowering, various antiinflammatory properties have been ascribed to statins. Moreover, in vitro studies have suggested the presence of anticoagulant effects of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, as lipopolysaccharide (LPS)-induced monocyte tissue factor (TF) was suppressed. In this study, we examined the role of statins in experimental endotoxemia on inflammatory and procoagulant responses in vivo. METHODS AND RESULTS: In this double-blind, placebo-controlled, parallel-group study, 20 healthy, male subjects were randomized to receive either simvastatin (80 mg/d) or placebo for 4 days before intravenous administration of LPS (20 IU/kg IV). Plasma high-sensitive C-reactive protein (hsCRP), monocyte chemoattractant protein (MCP-1), sCD40L, sCD40, and prothrombin fragment F1+2 (F1.2) were determined by ELISAs at baseline and at 4 and 8 hours after LPS administration. Monocyte TF expression and monocyte-platelet aggregates were measured by whole-blood flow cytometry over the same time course. The increases in hsCRP and MCP-1, both known inducers of TF, were significantly suppressed by statin treatment after LPS challenge. Statin premedication blunted the increase of monocyte TF expression in response to LPS. In parallel, endotoxin-induced formation of F1.2 was significantly reduced by simvastatin after 4 and 8 hours. LPS infusion affected neither the formation and activation of monocyte-platelet aggregates nor plasma levels of sCD40 and sCD40L. CONCLUSIONS: Simvastatin suppresses the inflammatory response to endotoxin and blunts monocyte TF expression but does not affect platelet activation.

Asymmetrical dimethylarginine plasma concentrations are related to basal nitric oxide release but not endothelium-dependent vasodilation of resistance arteries in peritoneal dialysis patients.

Vascular dysfunction in chronic renal failure may be linked to reduced nitric oxide (NO) bioactivity and increased circulating concentrations of the endogenous NO synthase inhibitor asymmetrical dimethyl L-arginine (ADMA). The association between ADMA and basal endothelial NO release and endothelium-dependent vasodilation in resistance arteries of chronic renal failure patients is unknown. Forearm blood flow responses to the endothelium-dependent vasodilator acetylcholine, the endothelium-independent vasodilator nitroglycerine, and the endothelium-dependent vasoconstrictor N(G)-monomethyl-L-arginine (L-NMMA) were assessed in 37 peritoneal dialysis patients. L-arginine and ADMA plasma concentrations were measured by HPLC. ADMA (mean +/- SEM: 0.68 +/- 0.02 micromol/L) was associated with basal forearm blood flow (r = -0.33; P < 0.05) and L-NMMA induced vasoconstriction (r = -0.55; P < 0.0005), but not with dilator effects of acetylcholine or nitroglycerine. L-arginine (68 +/- 3 micromol/L) tended to correlate with acetylcholine-induced vasodilation (r = 0.32; P = 0.05) but was not associated with other parameters. ADMA is related to basal but not to acetylcholine-stimulated NO bioactivity in patients on peritoneal dialysis. Impaired endothelium-dependent vasodilation found in chronic renal failure is not explained by elevated circulating NO synthase inhibitors in renal failure.

Regular physical exercise normalizes elevated asymmetrical dimethylarginine concentrations in patients with type 1 diabetes mellitus.

INTRODUCTION: Levels of the endogenous nitric oxide synthase inhibitor asymmetrical dimethylarginine (ADMA) are elevated in patients with type 1 diabetes mellitus (DM1) and may contribute to vascular complications. In this study we tested the hypothesis that elevated ADMA in patients with DM1 can be reduced by regular physical exercise. METHODS: Plasma samples for analysis of L-arginine, ADMA, symmetrical dimethylarginine (SDMA) and metabolic parameters were obtained from 11 patients with DM1 who participated in a supervised aerobic exercise program for four months. Samples were collected before the training began, at two and four months after initiation, and eight months after cessation of regular training. Fifteen age- and sex-matched healthy persons who did not exercise regularly were examined once as controls and did not participate in the training program. RESULTS: The patients with DM1 had higher ADMA levels than the controls before the training program began (0.54 +/- 0.02 vs. 0.44 +/- 0.03 micromol/l; P < 0.05). After two and four months of exercise, ADMA concentrations in the patients decreased to those seen in healthy persons (0.42 +/- 0.02 and 0.43 +/- 0.03 micromol/l; P < 0.001 and P < 0.05 compared with ADMA levels before training began). Eight months after cessation of the exercise program, ADMA levels in the patients reverted to those observed before the start of training. The L-arginine-to-ADMA ratio increased slightly after two months; L-arginine, symmetrical dimethylarginine, blood lipids and HbA1c were not affected by the training program. CONCLUSIONS: Elevated ADMA levels in patients with DM1, who have a high risk for developing cardiovascular disease, can be lowered to those of healthy persons by regular physical exercise. This favorable effect on ADMA is not sustained when training is discontinued.