Georg Schaller

A Proinflammatory State Is Detectable in Obese Children and Is Accompanied by Functional and Morphological Vascular Changes

Background—Obesity is generally accepted as a risk factor for premature atherosclerosis. Subclinical inflammation as quantified by blood levels of C-reactive protein (CRP) contributes to the development and progression of atherosclerosis. We hypothesized that inflammation in obese children is related to functional and early morphological vascular changes. Methods and Results—Blood levels of high sensitivity (hs) CRP, hsIL-6, the soluble intercellular adhesion molecule1 (ICAM-1), vascular cell adhesion molecule (VCAM)-1, and E-selectin were measured in 145 severely obese (body mass index [BMI], 32.2±5.8 kg/m2) and 54 lean (BMI, 18.9±3.2 kg/m2) children 12±4 years old. Flow-mediated dilation (FMD) of the brachial artery and carotid intima-media thickness (IMT) measured by high-resolution ultrasound as markers of early vascular changes were assessed in 92 (77 obese and 15 lean) and 59 (50 obese and 9 lean) children, respectively. Obese children had significantly higher levels of hsCRP, hsIL-6, and E-selectin than healthy controls (4.1±4.8 versus 0.9±1.5 mg/L, P<0.001 for hsCRP; 1.99±1.30 versus 1.42±1.01 pg/mL, P=0.05 for hsIL-6; and 78±38 versus 59±29 ng/mL, P=0.01 for E-selectin). There were no differences in the levels of ICAM-1 and VCAM-1 between groups. Obese children had lower peak FMD response (7.70±6.14 versus 11.06±3.07%, P=0.006) and increased IMT (0.37±0.04 versus 0.34±0.03 mm, P=0.03) compared with controls. Morbidly obese children (n=14, BMI 44.1±3.9 kg/m2) had highest levels of hsCRP (8.7±0.7 mg/L), hsIL-6 (3.32±1.1 pg/mL), and E-selectin (83±40 ng/mL). Conclusions—A proinflammatory state is detectable in obese children, which is accompanied by impaired vascular endothelial function and early structural changes of arteries, even in young subjects at risk. It remains to be determined whether high hsCRP in obese children predicts cardiovascular events.

Simvastatin Prevents Vascular Hyporeactivity During Inflammation

Background—There is growing evidence that statins exert anti-inflammatory and antioxidative vascular actions that are independent of lipid lowering. We tested whether hyporeactivity to the endothelium-dependent vasodilator acetylcholine (ACh) and the vasoconstrictor norepinephrine (NE) during acute experimental inflammation could be prevented by simvastatin. Methods and Results—In a randomized, placebo-controlled, parallel group study, forearm blood flow (FBF) responses to NE, ACh, and the endothelium-independent vasodilator nitroglycerin (NTG) were assessed at baseline, after 4 days of simvastatin 80 mg PO or placebo treatment, and during Escherichia coli endotoxin (lipopolysaccharide [LPS])–induced inflammation in 20 healthy volunteers. Additionally, markers of inflammation and neutrophil oxidative burst were assessed. Simvastatin and placebo had no effect on FBF or oxidative/inflammatory markers. LPS administration decreased the responses of FBF to NE by 43% (P<0.05) and decreased responses to ACh by 48% (P<0.05) but did not decrease FBF responses to NTG. Simvastatin completely preserved responses to NE and to ACh. The LPS-induced increases in neutrophil oxidative burst and plasma tumor necrosis factor-α concentrations were mitigated by simvastatin (P<0.05 versus placebo). Conclusions—This study demonstrates potent vasoprotective properties of high-dose simvastatin during endotoxemia that may be useful for patients with acute systemic inflammation and associated vascular hyporeactivity.

The adipokine visfatin is markedly elevated in obese children.

Objective: The insulin-mimetic adipocytokine visfatin has been linked to adiposity and the metabolic syndrome. Design Cross-sectional study. Subjects: Eighty-three nondiabetic obese children and 40 healthy controls. Measurements: We analyzed plasma visfatin concentrations to assess whether this adipokine is associated with adiposity. Results: Plasma visfatin concentrations were nearly 2-fold higher in obese children (mean, 1.1 ng/mL; 95% CI, 0.2-6.6) than in controls (0.6 ng/mL, 95% CI, 0.6 to 0.6; P < 0.001). No relationship was detectable between visfatin and other subject characteristics, hsCRP or the lipid profile. Conclusions: Visfatin may be involved in the development of metabolic derangements in obese children.

Alpha-lipoic acid improves vascular endothelial function in patients with type 2 diabetes: a placebo-controlled randomized trial

Eur J Clin Invest 2010; 40 (2): 148–154

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.

Vascular function in obese children with non-alcoholic fatty liver disease

OBJECTIVE To test whether obese children with non-alcoholic fatty liver disease have impaired vascular function compared with obese children with normal liver fat content. METHODS Obese children (n = 28, 16 males, mean age 10.9 ± 0.7 years, body mass index [BMI] 31.9 ± 4.5 kg/m(2)) with normal (HCLn) and increased hepatocellular lipid content (HCLi, 2.6 ± 0.8 vs. 12.4 ± 8.2%) were recruited, outcome measures being flow-mediated dilation of the brachial artery [FMD] measured by ultrasound, biochemical markers of inflammation (hs-CRP, hs-IL6) and cell adhesion molecules [CAMs], hepatocellular lipids, visceral and subcutaneous fat quantified by nuclear magnetic resonance spectroscopy and imaging. RESULTS HCLi and HCLn groups showed no significant differences in terms of age, gender, BMI, waist circumference and subcutaneous fat. Subjects in the HCLi group had significantly higher amounts of visceral fat and higher fasting glucose, insulin and triglyceride, but lower adiponectin levels and were more insulin resistant than their HCLn controls. Hepatic fat fraction (HFF) correlated positively with fasting plasma glucose, HOMA-IR, adiponectin, visceral fat, negatively with WBISI independent of BMI. HFF was not associated with subcutaneous fat, fasting insulin, FFA, HDL-C, TG, hs-CRP, hs-IL6, vCAM, iCAM, and FMD. HCLi patients had significantly higher serum levels of hs-CRP and hs-IL6 than HCLn controls. FMD and serum levels of vCAM and iCAM were comparable between groups. CONCLUSIONS Obese children with simple steatosis rather than steatohepatitis seem to have intact vascular function. Further studies in obese children with different grades of NAFLD are warranted to elucidate the role of fatty liver as a marker of risk for future cardiovascular events.

Impaired vascular nitric oxide bioactivity in women with previous gestational diabetes

ZusammenfassungHINTERGRUND: Eine Dysfunktion des Gefäß-Endothels, die vaskulären Erkrankungen und Typ 2 Diabetes vorausgehen kann, zeigt sich bei Patientinnen nach Gestationsdiabetes. Es ist allerdings nicht geklärt ob Adipositas, asymetrisches Dimethylarginin (ADMA), ein endogener Stickstoffmonoxid (NO) Synthese Inhibitor oder Insulin-Resistenz die beobachteten Gefäß-Veränderungen bei diesen Patientinnen zusätzlich verstärken. Ziel dieser Studie war es daher, Faktoren zu finden, die die Gefäß-Dysfunktion zusätzlich zum Gestationsdiabetes beeinträchtigen. METHODEN: 7 übergewichtige und 5 normalgewichtigen Patientinnen nach Gestationsdiabetes wurden in diese Studie eingeschlossen. Die Gefäß-Funktion wurde durch Änderungen des Unterarm-Blutflusses auf den Endothel-abhängigen Vasodilatator Acetylcholin (ACh), den Endothel-unabhängigen Vasodilatator Nitroglycerin (GTN), den Vasokonstriktor Norepinephrin (NE) und den NO-Synthase Inhibitor N(G)-monomethyl-L-arginine (L-NMMA) gemessen. ADMA wurde aus venösen Blutproben bestimmt und die Insulin-Resistenz wurde mittels eines modifizierten intravenösen Glukose-Toleranz Tests abgeschätzt. 20 gesunde, männliche Probanden dienten als historische Kontroll-Gruppe. RESULTATE: Verglichen mit Normalgewichtigen war die Reaktion des Unterarm-Blutflusses auf ACh bei übergewichtigen Frauen gestört (p < 0.05); ebenso war die Antwort auf den Vasokonstriktor NE tendenziell bei dieser Gruppe verringert. Weiters gab es signifikante Korrelationen zwischen der vaskulären Antwort auf ACh beziehungsweise L-NMMA und Body Mass Index, Serum ADMA Konzentrationen und stimulierten Glukose Werten (alle p < 0.05). Normalgewichtigen Patientinnen hatten mit der gesunden Kontrollgruppe vergleichbares Ansprechen auf ACh und ADMA Konzentrationen. SCHLUSSFOLGERUNG: Faktoren wie Übergewicht, erhöhte ADMA Werte und Insulin-Resistenz dürften starken Einfluss auf die Endotheliale Dysfunktion bei Patientinnen nach Gestationsdiabetes haben.SummaryBACKGROUND: 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-α, 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.

Effect of systemic vitamin C on free fatty acid-induced lipid peroxidation

OBJECTIVES Plasma malondialdehyde (MDA), a reactive product of lipid peroxidation, may be influenced by anti-oxidant therapy. The aim of the present study was to investigate if elevated MDA as induced by increased free fatty acids (FFA) correlates with endothelial function and is affected by high doses of vitamin C. METHODS The study design was randomised, placebo-controlled, double blind, 2-way cross over. Plasma MDA concentrations and forearm blood flow (FBF) responses to intra-arterial acetylcholine (ACh) and glyceryl trinitrate were assessed during co-administration of vitamin C or placebo in the presence of increased plasma FFA by Intralipid/heparin infusion in 10 healthy male subjects. RESULTS The seven-fold rise in plasma FFA was associated with an increase in plasma MDA concentrations (r=0.7, p<0.001) and decreased FBF responses to ACh (r=-0.4, p<0.01). Co-administration of vitamin C restored the impaired reactivity of FBF to ACh but had no effect on elevated MDA concentrations. CONCLUSIONS Anti-oxidant vitamin C improves lipid-induced impairment of endothelium-dependent vasodilation, but does not alter MDA formation or breakdown.

Human pharmacokinetics of intravenous recombinant human Cu/Zn superoxide dismutase.

OBJECTIVE Oxidative stress plays an important role in human disease, but antioxidant therapies are limited. Under physiological conditions superoxide is controlled by the enzyme superoxide dismutase. A recombinant human Cu/Zn superoxide dismutase (rhSOD) might open new therapeutic possibilities. METHODS Safety profile and pharmacokinetics in plasma and urine were assessed in an open label phase I study with dose-escalation. 18 healthy male volunteers received a single intravenous 10-minute infusion of 150, 300, or 600 mg rhSOD, respectively (n = 6 per dose group). RESULTS rhSOD was well tolerated. Peak plasma concentrations (cmax; mean ± SD) were reached at the end of infusion, with 32.96 ± 10.31, 51.60 ± 8.23, and 103.90 ± 19.02 μg/ ml, respectively. Non-compartmental halflife was 1.06 ± 0.37, 1.59 ± 0.64, and 1.63 ± 0.28 hours. Urinary excretion (10 h) showed dose-dependent relative increases with 11.28 ± 6.46 (7.5%), 54.93 ± 15.25 (18.3%), and 191.81 ± 104.60 mg (32.0%). CONCLUSIONS Our results show a good safety profile and predictable pharmacokinetics of rhSOD, suggesting that therapeutic exploratory studies might be safely conducted in humans.