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Biomedical subjects

Michael Böhm

Publications and source records attributed to Michael Böhm.

At least 55 records · Page 3Linked to original sources
PubMed2005

Physical inactivity increases oxidative stress, endothelial dysfunction, and atherosclerosis.

OBJECTIVE: Sedentary lifestyle is associated with increased cardiovascular events. The underlying molecular mechanisms are incompletely understood. Reactive oxygen species (ROS) contribute to endothelial dysfunction and atherosclerosis. An important source of vascular ROS is the NADPH oxidase. METHODS AND RESULTS: C57BL6 mice were subjected to regular housing (physical inactivity) or voluntary training on running wheels (6 weeks). Inactivity increased vascular lipid peroxidation to 148+/-9% and upregulated superoxide release to 176+/-17% (L-012 chemiluminescence) and 188+/-29% (cytochrome C reduction assay), respectively. ROS production was predominantly increased in the endothelium and the media (dihydroethidium fluorescence). Activity of the NADPH oxidase was increased to 154+/-22% in the sedentary group. Rac1 GST-PAK pull-down assays showed an upregulation of rac1 activity to 161+/-14%. Expression levels of the subunits nox1, p47phox, and p67phox were increased. To address the significance of the antioxidative effects of running, experiments were repeated in apolipoprotein E-deficient mice treated with a high-cholesterol diet. Inactivity increased vascular superoxide production and impaired endothelium-dependent vasorelaxation. Atherosclerotic lesion formation was significantly accelerated in sedentary mice. CONCLUSIONS: Inactivity increases vascular NADPH oxidase expression and activity and enhances vascular ROS production, which contributes to endothelial dysfunction and atherosclerosis during sedentary as opposed to physically active lifestyle.

Animals↗
PubMed2005

Randomized trial to determine the effect of nebivolol on mortality and cardiovascular hospital admission in elderly patients with heart failure (SENIORS).

AIMS: Large randomized trials have shown that beta-blockers reduce mortality and hospital admissions in patients with heart failure. The effects of beta-blockers in elderly patients with a broad range of left ventricular ejection fraction are uncertain. The SENIORS study was performed to assess effects of the beta-blocker, nebivolol, in patients >/=70 years, regardless of ejection fraction. METHODS AND RESULTS: We randomly assigned 2128 patients aged >/=70 years with a history of heart failure (hospital admission for heart failure within the previous year or known ejection fraction </=35%), 1067 to nebivolol (titrated from 1.25 mg once daily to 10 mg once daily), and 1061 to placebo. The primary outcome was a composite of all cause mortality or cardiovascular hospital admission (time to first event). Analysis was by intention to treat. Mean duration of follow-up was 21 months. Mean age was 76 years (SD 4.7), 37% were female, mean ejection fraction was 36% (with 35% having ejection fraction >35%), and 68% had a prior history of coronary heart disease. The mean maintenance dose of nebivolol was 7.7 mg and of placebo 8.5 mg. The primary outcome occurred in 332 patients (31.1%) on nebivolol compared with 375 (35.3%) on placebo [hazard ratio (HR) 0.86, 95% CI 0.74-0.99; P=0.039]. There was no significant influence of age, gender, or ejection fraction on the effect of nebivolol on the primary outcome. Death (all causes) occurred in 169 (15.8%) on nebivolol and 192 (18.1%) on placebo (HR 0.88, 95% CI 0.71-1.08; P=0.21). CONCLUSION: Nebivolol, a beta-blocker with vasodilating properties, is an effective and well-tolerated treatment for heart failure in the elderly.

Adrenergic beta-Antagonists↗
PubMed2005

Current therapy of pulmonary hypertension.

Pulmonary arterial hypertension (PAH) affects vascular proliferation and remodeling in small pulmonary arteries and results in right ventricular failure and death due to a progressive increase in pulmonary vascular resistance. Recent advances in understanding of the molecular mechanisms involved in PAH suggest that endothelial dysfunction plays a major role. Impaired production of vasoactive mediators, such as prostacyclin and nitric oxide, accompanied with prolonged overexpression of vasoconstrictors such as endothelin-1, affects vascular tone and reinforces vascular remodeling. As the latter substances represent logical pharmacological targets, new drugs affecting these mechanisms have evolved during the past 2 decades and led to umpteen placebo-controlled trials in bygone years. Prognosis and quality of life of patients suffering from PAH seem to improve due to these new treatment strategies resulting in a reduction of mortality and morbidity, but there is still a substantial need for further long-term and head-to-head trials.

Antihypertensive Agents↗
PubMed2005

[Referral to the pediatric dialysis unit -- the earlier the better?].

Whereas recent research has demonstrated clear evidence for beneficial effects of early referral to the nephrologist in chronic renal insufficiency in adults, no such data exist for the pediatric population. In this study, we therefore correlated patient age and residual renal function at first presentation to a specialized pediatric nephrologist with the extent of secondary uremic complications and the further course of renal function. From March 2003 until March 2004, 43 children (34 boys, aged 10.1 +/- 6.3 yrs) with congenital-urologic (n = 26), congenital-nephrologic (n = 13) or acquired (n = 4) renal diseases had been followed for 3.9 yrs (14 days to 17.5 yrs) at the Kinderdialyse Wien, with a residual renal function of 35 +/- 20.5 ml/min/1.73 m(2) at first presentation. With regards to uremic secondary complications, the majority of children exhibited involvement of at least two systems at first presentation. Thereafter, children with congenital diseases who were referred to the specialized pediatric nephrology unit within the first year of live demonstrated a significantly better course of residual renal function (1.8% vs -0.7%, p = 0.034) than children who were referred later. These data confirm recent registry reports on chronic renal insufficiency in children. Only about a third of the children of our population were presented to a specialized pediatric nephrology center within their first year of life (despite a congenital disease in 90% of them). Thus, therapeutic interventions might be currently offered at a delayed time point in the majority of children.

Austria↗
PubMed2005

Does "electromagnetic pollution" cause illness? An inquiry among Austrian general practitioners.

More and more self-declared electromagnetic hypersensitive patients are entering physicians' practices seeking help. To assess the prevalence of cases and the opinion of Austrian physicians regarding the potential health-relevance of environmental electromagnetic fields ("electromagnetic pollution"), a statistical investigation among general practitioners was undertaken, with surprising results. Only one-third report on never having been asked about the health impact of electromagnetic pollution by patients. An overwhelming percentage of general practitioners (up to 96%) to some degree, or totally, believe in a health-relevant role of environmental electromagnetic fields, and only 39% have never associated health symptoms with "electromagnetic pollution". Two-thirds are consulted occasionally or even frequently by self-declared electromagnetic hypersensitive patients. However, sound information seems to be lacking. Knowledge on existing electromagnetic exposure limits and on environmental field levels in relation to them is poor. It is remarkable that authorities play a marginal role in informing physicians. Only 4% mention having received information on "electromagnetic pollution" from such a source. It is rather remarkable that there is such a widespread contradiction between physicians' opinions and established national and international health risk assessment. With respect to the frequency with which doctors are confronted with this issue, the results demonstrate an urgent need for action.

Attitude of Health Personnel↗
PubMed2005

Randomized comparison of anterolateral versus anteroposterior electrode position for biphasic external cardioversion of atrial fibrillation.

BACKGROUND: In biphasic external cardioversion (CV) of atrial fibrillation (AF), the influence of different electrode positions on efficacy and incidence of early recurrent atrial fibrillation is not known. This study compared anteroposterior (AP) vs anterolateral (AL) electrode positioning. METHODS: Consecutive patients referred for CV of persistent AF were randomized either to an AP or an AL electrode position. Biphasic external CV was performed with standardized electrode positions and rising energy delivery. RESULTS: Both groups (N = 123, mean age 66 years, 71% male, 83% with structural cardiovascular disease or hypertension) did not differ concerning age, sex, body mass index, chronic antiarrhythmic therapy, duration of AF, left ventricular ejection fraction, and left atrial diameter. Cumulative success rates were comparable (AP 94.9% vs AL 95.2%, P = ns). First-shock efficacy did not differ (AP 78.3% vs AL 74.6%, P = ns). Early recurrent atrial fibrillation (AF relapse < 1 minute after successful CV) occurred in 8.1% (AP 11.6% vs AL 4.8%, P = ns). Mean number of shocks was 1.3 per patient with the AP configuration and 1.4 per patient with the AL configuration (P = ns). Mean cumulative energy delivery was also comparable (AP 171 WS vs AL 198 WS, P = ns). CONCLUSIONS: Both electrode positions are similar in biphasic external CV of AF with regard to acute success and early recurrent atrial fibrillation. Also, the number of shocks needed and energy delivery are comparable with both electrode configurations.

Aged↗
PubMed2005

Myocardial regeneration by endogenous adult progenitor cells.

New strategies are urgently needed for the treatment of terminal heart-failure. Recently, new therapeutic strategies were developed to induce cardiac regeneration and thereby enhancing myocardial performance by using the patients own cell pool. In the quest for adequate donor cells skeletal myoblasts, bone marrow (BM) derived cells, endothelial progenitor cells (EPCs) and resident cardiac stem cells but also cytokine application were examined. This review critically discusses the recent findings in the field of endogenous adult progenitor cells and proposes new areas for future research.

Adult↗
PubMed2005

Running exercise of different duration and intensity: effect on endothelial progenitor cells in healthy subjects.

BACKGROUND: Increased numbers of circulating endothelial progenitor cells (EPC) are associated with improved vascular function. Exercise is a central component of the primary prevention of vascular diseases. The effect of physical activity on circulating EPC in healthy individuals is not known. DESIGN: A prospective crossover study. METHODS AND RESULTS: In order to study a potential link between the extent of physical exercise and progenitor cells in humans, EPC were quantified by flow cytometry and cell culture in 25 healthy volunteers undergoing three protocols of running exercise. Intensive running, defined as 30 min at 100% of the velocity of the individual anaerobic threshold (IAT; approximately 82% maximal oxygen consumption; VO2max), as well as moderate running with 30 min at 80% of the velocity of the IAT ( approximately 68% VO2max), increased circulating EPC numbers to 235+/-93% and 263+/-106% of control levels, respectively. However, moderate short-term running for 10 min did not upregulate EPC counts. The maximum increase in circulating EPC numbers was observed 10-30 min after intensive running. Exercise increased EPC migratory and colony-forming capacity. CONCLUSIONS: Intensive and moderate exercising for 30 min, but not for 10 min, increased circulating levels of EPC, which may represent an important beneficial outcome of physical exercise. The data support the notion that increased numbers of EPC correlate with cardiovascular health and suggest EPC quantification as a novel surrogate parameter of the vascular effects of exercising.

Adult↗
PubMed2004

Vascular response to angiotensin II predicts long-term prognosis in patients undergoing coronary artery bypass grafting.

Persistent activation of the renin-angiotensin system leads to downregulation of the angiotensin type-1 receptor, and consequently, to a decreased response to exogenous angiotensin II. In the present study, we investigated the association of angiotensin II responsiveness to clinical outcome after coronary artery bypass grafting (CABG). We studied the responsiveness to exogenous angiotensin II in human thoracic artery preparations of 114 CABG patients. Mean duration of follow-up was 7.3+/-0.1 years, during which 21 patients experienced a cardiovascular event. A diminished response to angiotensin II remained in multivariate Cox regression analysis, after adjustment for sex, age, blood pressure, and number of diseased coronary arteries, the strongest predictor for cardiovascular events (relative risk, 3.37 [95% confidence interval, 1.20 to 9.51]; P=0.022). Furthermore, diminished response to angiotensin II was associated with an increased mean arterial pressure (102.85+/-1.38 versus 97.40+/-1.37; P=0.003) and a nonsignificant increase in angiotensin-converting enzyme activity, suggestive for a persistently activated renin-angiotensin system. In conclusion, these results suggest that in patients undergoing CABG, a diminished vascular responsiveness of the thoracic artery to exogenous angiotensin II is related to an increased risk of future cardiovascular events.

Aged↗
PubMed2004

Paclitaxel balloon coating, a novel method for prevention and therapy of restenosis.

BACKGROUND: Drug-eluting stents have shown promising antirestenotic effects in clinical trials. Non-stent-based local delivery of antiproliferative drugs may offer additional flexibility and also reach vessel areas beyond the immediate stent coverage. The aim of the present study was to evaluate a novel method of local drug delivery based on angioplasty balloons. METHODS AND RESULTS: Stainless steel stents (n=40; diameter, 3.0 to 3.5 mm; length, 18 mm) were implanted in the left anterior descending and circumflex coronary arteries of domestic pigs. Both conventional uncoated and 3 different types of paclitaxel-coated, percutaneous transluminal coronary angioplasty balloons (contact with vessel wall for 1 minute) were used. No difference in short-term tolerance between coated and uncoated balloons and no signs of thrombotic events were observed. Quantitative angiography and histomorphometry of the stented arteries asserted the statistical equality of the baseline parameters between the control and the 3 treatment groups. Paclitaxel balloon coating led to a marked, dose-dependent reduction of parameters characterizing in-stent restenosis (reduction of neointimal area up to 63%). Despite the marked reduction in neointimal proliferation, endothelialization of stent struts was present in all samples. There was no evidence of a significant inflammatory response in the neighborhood of the stent struts. CONCLUSIONS: Paclitaxel balloon coating is safe, and it effectively inhibits restenosis after coronary angioplasty with stent implantation in the porcine model. The degree of reduction in neointimal formation was comparable to that achieved with drug-eluting stents.

Angioplasty, Balloon, Coronary↗