Thomas C. Wascher

A common 936 C/T gene polymorphism of vascular endothelial growth factor is associated with decreased breast cancer risk

A common 936 C/T polymorphism in the gene for the vascular endothelial growth factor (VEGF) has been associated with VEGF plasma levels. In our case‐control study, we investigated the role of this polymorphism for breast cancer risk. VEGF genotype was determined in 500 women with breast cancer and 500 sex‐ and age‐matched healthy control subjects. Carriers of a 936T‐allele were more frequent among controls (29.4%) than among patients (17.6%; p = 0.000014). The odds ratio for carriers of a 936T‐allele for breast cancer was 0.51 (95% confidence interval 0.38–0.70). Additionally, VEGF plasma levels were determined in 21 nonsmoking post‐menopausal controls; carriers of a 936T allele had significantly lower levels (median 23 pg/ml; range 6–50 pg/ml) than noncarriers (37; 21–387; p = 0.034). We conclude that carriers of a VEGF 936T‐allele are at decreased risk for breast cancer, this, however, requiring further confirmation in a larger study.

Endothelial Dysfunction Induced by Hyperhomocyst(e)inemia Role of Asymmetric Dimethylarginine

Background—Endothelial function is impaired by hyperhomocyst(e)inemia. We have previously shown that homocyst(e)ine (Hcy) inhibits NO production by cultured endothelial cells by causing the accumulation of asymmetric dimethylarginine (ADMA). The present study was designed to determine if the same mechanism is operative in humans. Methods and Results—We studied 9 patients with documented peripheral arterial disease (6 men; 3 women; age, 64±3 years), 9 age-matched individuals at risk for atherosclerosis (older adults; 9 men; age, 65±1 years), and 5 young control subjects (younger adults; 5 men; age, 31±1 years) without evidence of or risk factors for atherosclerosis. Endothelial function was measured by flow-mediated vasodilatation of the brachial artery before and 4 hours after a methionine-loading test (100 mg/kg body weight, administered orally). In addition, blood was drawn at both time points for measurements of Hcy and ADMA concentrations. Plasma Hcy increased after the methionine-loading test in each group (all, P <0.001). Plasma ADMA levels rose in all subjects, from 0.9±0.2 to 1.6±0.2 &mgr;mol/L in younger adults, from 1.5±0.2 to 3.0±0.4 &mgr;mol/L in older adults, and from 1.8±0.1 to 3.9±0.3 &mgr;mol/L in peripheral arterial disease patients (all, P <0.001). Flow-mediated vasodilatation was reduced from 13±2% to 10±1% in younger adults, from 6±1% to 5±1% in older adults, and from 7±1% to 3±1% in peripheral arterial disease patients (all, P <0.001). Furthermore, we found positive correlations between plasma Hcy and ADMA concentrations (P =0.03, r =0.450), as well as ADMA and flow-mediated vasodilatation (P =0.002, r =0.623). Conclusions—Our results suggest that experimental hyperhomocyst(e)inemia leads to accumulation of the endogenous NO synthase inhibitor ADMA, accompanied by varying degrees of endothelial dysfunction according to the preexisting state of cardiovascular health.

Exposure To Elevated D-Glucose Concentrations Modulates Vascular Endothelial Cell Vasodilatory Response

The possible role of endothelial dysfunction in early stages of uncomplicated diabetes mellitus was investigated in porcine aortic endothelial cells. Prolonged exposure to various D-glucose concentrations resulted in concentration-dependent amplification of agonist-induced Ca2+ mobilization, whereas L-glucose and D-mannitol failed to mimic the effect of D-glucose. This stimulatory effect of high D-glucose on endothelial Ca2+ mobilization could be antagonized by coincubation with cytochalasin B, which prevented D-glucose uptake into the cells. In agreement with its effect on agonist-induced Ca2+ response, prolonged preincubation with pathological D-glucose concentrations amplified formation of endothelium-derived relaxing factor, which is well established to be strictly attributable to increases in endothelial free Ca2+. In contrast to endothelium-derived relaxing factor formation stimulated by receptor-interacting autacoids, preincubation with high D-glucose failed to modulate A 23,187-induced endothelium-derived relaxing factor formation, which is attributable to unphysiological increases in endothelial free Ca2+ by this ionophore. Similar to its effect on D-glucose-mediated amplification of agonist-stimulated Ca2+ mobilization, cytochalasin B abolished the stimulatory effect of high D-glucose on endothelium-derived relaxing factor formation. We therefore suggest that prolonged exposure to pathological high D-glucose concentrations results in an enhanced endothelium-derived relaxing factor formation caused by amplification of agonist-stimulated Ca2+ mobilization in endothelial cells. This mechanism may be of particular importance representing a possible basis of pathological vasodilation and reduced peripheral resistance in early stages of diabetes mellitus.

Increased superoxide anion formation in endothelial cells during hyperglycemia: an adaptive response or initial step of vascular dysfunction?

In diabetes mellitus, the risk for cardiovascular complications and development of atherosclerosis is increased compared with healthy individuals. Recently evidence was provided that increased production of superoxide anions occurs in endothelial cells during hyperglycemia. In order to evaluate the potential impact of the enhanced formation of this oxygen radical for vascular cell dysfunction and its role in tissue adaptation, it is essential to assess the effect of superoxide anions on endothelial cell function. Here, we present new data and review our previous work on the effects of superoxide anions on endothelial vascular function, such as intracellular Ca2+ signal cascade, formation and bioactivity of nitric oxide. Based on the presented data we discuss superoxide anion production as a two faced phenomenon. In lower concentrations, superoxide anions are mediators of an endothelium adaptation to ensure endothelial vasomotion control. However, in higher concentrations superoxide anions disrupt endothelial-smooth muscle crosstalk resulting in vessel wall dysfunction and vascular wall dysfunction.

INTERLEUKIN-10 PROMOTER POLYMORPHISM IS ASSOCIATED WITH DECREASED BREAST CANCER RISK

Interleukin-10 (IL-10) is an immunosuppressive cytokine which may facilitate development of cancer by supporting tumor escape from the immune response. A [TCATA] haplotype formed by polymorphisms at positions −3575, −2763, −1082, −819 and −592 in the promoter of the IL-10 gene is a strong determinant for IL-10 expression. The presence of this haplotype can be determined by analysis of the −592C > A polymorphism. Aim of the present study was to analyze the role of the IL-10 [TCATA] haplotype for breast cancer. We performed a case–control study including 500 female patients with histologically confirmed breast cancer and 500 female, age-matched, healthy control subjects from population-based screening studies. The −592C > A polymorphism was determined by a 5′-nuclease assay (TaqMan). Frequency of the homozygous −592 AA genotype, indicating homozygosity for the [TCATA] haplotype, was 4.2% among patients and 7.3% among controls (p=0.038; odds ratio 0.56; 95% confidence interval 0.32–0.97). IL-10 genotypes were not associated with tumor size, histological grading, estrogen or progesterone receptor status and age at diagnosis. Therefore we conclude that the IL-10 −592C > A promoter polymorphism may be associated with a reduced breast cancer risk.

Prothrombin G20210A, factor V Leiden, and factor XIII Val34Leu: common mutations of blood coagulation factors and deep vein thrombosis in Austria.

Mutations in the gene for prothrombin (F2 20210A) and factor V (F5 1691A, factor V Leiden) are established risk factors for deep venous thrombosis (DVT). Recently, a mutation in the gene for factor XIII (F13 100T) leading to a Valine-Leucine exchange at amino acid position 34 has been reported to be protective against DVT. To analyze the role of these mutations for DVT in Austria, we analyzed their prevalence in 154 patients with documented DVT and 308 sex- and age-matched control subjects. Allele frequencies of F2 20210A, F5 1691A, and F13 100T were 0.018, 0.039, and 0.274 among controls, and 0.045, 0.120, and 0.211 among patients, respectively. Odds ratios for DVT associated with F2 20210A, F5 1691A, and F13 100T alleles were 2.5 (95% CI: 1.1-5.7), 3.4 (95% CI: 1.9-5.8), and 0.7 (95% CI: 0.5-1.0). We conclude that F2 20210A, F5 1691A, and F13 100T are common mutations in the Austrian population. F2 20210A and F5 1691 increase the risk for DVT, whereas F13 100T is associated with a decreased risk for DVT. Routinely, analysis of these mutations may help to analyze the individual risk for DVT.

Intracellular mechanism of high D-glucose-induced modulation of vascular cell proliferation.

Development of atherosclerosis in diabetes patients is thought to be associated with high D-glucose-induced changes in vascular cell proliferation. This study was designed to investigate the intracellular mechanisms of altered proliferation in porcine aortic endothelial and smooth muscle cells under high D-glucose conditions. Two different technical approaches were used for determination of cell proliferation, a cell counting procedure and bromodeoxyuridine incorporation. D-Glucose diminished endothelial cell proliferation (30.3%) and increased smooth muscle cell proliferation (143%) in a dose-dependent manner. Neither D-mannitol, sucrose nor L-glucose mimicked the effect of D-glucose. Inhibition of D-glucose uptake into vascular cells by cytochalasin B prevented the effect of high D-glucose on cell proliferation. The aldose-reductase inhibitors, sorbinil and zopolrestat, little affected high D-glucose-attenuated endothelial cell proliferation, while the enhanced proliferation of smooth muscle cells was prevented by aldose-reductase inhibitors. Elevation of cellular glutathione levels yielded protection of both cell types from high D-glucose-mediated changes in cell proliferation, suggesting that high D-glucose may act via generation of oxidative species. Finally, aminoguanidine was shown to constitute a very potent inhibitor of D-glucose-induced dysfunction in vascular cell proliferation. These data suggest that high D-glucose-induced changes in cell proliferation of endothelial and smooth muscle cells are related to specific D-glucose uptake rather than hyperosmolality. Aldose-reductase seems to be mainly involved in the effect of high D-glucose only on smooth muscle cell proliferation, while in endothelial cells there is (are) other factor(s) in addition to the sorbitol pathway involved in high D-glucose-induced changes in cell proliferation.

The influence of probiotic supplementation on gut permeability in patients with metabolic syndrome: an open label, randomized pilot study

Background/objectives:Obesity and metabolic disorders are linked to inflammation via gut microbiota and/or gut permeability. Gut-derived endotoxin triggers inflammation leading to metabolic syndrome (MetS) and contributing to oxidative stress. We intended to investigate the effect of Lactobacillus casei Shirota on gut permeability, presence of endotoxin and neutrophil function in MetS.Subjects/methods:Patients with MetS were randomized to receive 3 × 6.5 × 109 CFU L. casei Shirota (probiotic group) or not for 3 months. Gut permeability was assessed by a differential sugar absorption method and by determination of diaminooxidase serum levels, endotoxin by an adapted limulus amoebocyte lysate assay, neutrophil function and toll-like receptor (TLR) expression by flow cytometry and ELISA was used to detect lipopolysaccharide-binding protein (LBP) and soluble CD14 (sCD14) levels.Results:Twenty-eight patients and 10 healthy controls were included. Gut permeability was significantly increased in MetS compared with controls but did not differ between patient groups. None of the patients were positive for endotoxin. LBP and sCD14 levels were not significantly different from healthy controls. High-sensitive C-reactive protein and LBP levels slightly but significantly increased after 3 months within the probiotics group. Neutrophil function and TLR expression did not differ from healthy controls or within the patient groups.Conclusions:Gut permeability of MetS patients was increased significantly compared with healthy controls. L. casei Shirota administration in the MetS patients did not have any influence on any parameter tested possibly due to too-short study duration or underdosing of L. casei Shirota.

The L10P polymorphism of the transforming growth factor-beta 1 gene is not associated with breast cancer risk

Transforming growth factor-beta 1 (TGF-beta1) is a potent inhibitor of proliferation of epithelial, endothelial and hematopoietic cells and acts as a tumor suppressor. The gene for TGF-beta1, TGFB1, carries a common T/C variation of nucleotide 29, resulting in a leucine (L) to proline (P) polymorphism at codon 10 (TGFB1 L10P). The less common 10P allele has repeatedly been linked to higher TGF-beta1 levels and in at least one study to a lower incidence of breast cancer. To further analyze the role of this polymorphism for breast cancer risk, 500 patients with histologically confirmed breast cancer and 500 sex-and age-matched healthy control subjects were genotyped for the TGFB1 L10P polymorphism by an allele-specific polymerase chain reaction assay. TGFB1 LL, LP and PP genotype frequencies were not significantly different for patients (39.6, 44.2, 16.2%) and controls (36.5, 45.9, 17.6%). We conclude that the TGFB1 L10P polymorphism is not associated with breast cancer risk.

Chronic TNF-a neutralization does not improve insulin resistance or endothelial function in "healthy" men with metabolic syndrome

The possible contribution of tumor necrosis factor-α (TNF-α) to the development of obesity-associated insulin resistance in humans is still controversial. Our study investigated the effect of TNF-α neutralization on insulin resistance in healthy, obese and insulin resistant men. We performed a prospective, randomized, double-blind placebo-controlled trial in nine young, healthy obese male subjects with metabolic syndrome and insulin resistance. Volunteers received three infusions (wks 0, 2 and 6) of infliximab or placebo. Insulin resistance was measured at baseline and after 70 d by homeostatic model assessment (HOMA) index as well as by minimal model analysis of an intravenous glucose tolerance test. Endothelial function was accessed before and after intervention by flow mediated dilation. Infliximab improved the inflammatory status as indicated by reduced high sensitivity C-reactive protein (hsCRP) and fibrinogen levels (2.77 ± 0.6 to 1.8 ± 0.5 µg/L, and 3.42 ± 0.18 to 3.18 ± 0.28 g/L; (day 0 and day 70, P = 0.020 and 0.037 respectively), but did not improve insulin resistance (HOMA index and intravenous glucose-tolerance test [ivGGT]) or endothelial function. Despite improvements in inflammatory status, chronic TNF-α neutralization does not improve insulin resistance or endothelial function in seemingly healthy, but obese, insulin-resistant volunteers. This study severely questions the proposal that TNF-α is a causative link between adiposity and insulin resistance.