Biomedical subjects

Stephan Steiner

Publications and source records attributed to Stephan Steiner.

4 recordsLinked to original sources

PubMed2006

[Chemoreflexsensitivity is reduced in obstructive sleep apnea and might be modulated by the autonomic system].

BACKGROUND: Chemoreflexes are important mechanisms for regulating ventilatory and cardiovascular function, which are supposed to be influenced in obstructive sleep apnea (OSA). PATIENTS AND METHODS: For determination of chemoreflexsensitivity (CHRS) the ratio of the RR-interval shift in the surface ECG during 5 min inhalation of oxygen via a nose mask was formed in 15 patients with suspected OSA. Noradrenaline plasma concentrations were measured and were correlated to CHRS. RESULTS: Patients with OSA showed a reduced CHRS. CHRS was correlated to the severity of sleep apnea (respiratory disturbance index [RDI]; r = -0.622; p = 0.013), and to minimal nocturnal oxygen saturation (r = 0.594; p = 0.032). Reduced CHRS was associated with higher noradrenaline concentrations (r = -0.542; p = 0.037). CONCLUSION: CHRS is reduced in patients with OSA and correlates with the severity of OSA. Further on, CHRS might be modulated by the autonomic system. Therefore, the determination of CHRS enables to estimate sympathetic activation in these patients.

Adult↗

PubMed2006

[Effects of exercise training on mobilization of BM-CPCs and migratory capacity as well as LVEF after AMI].

BACKGROUND AND PURPOSE: Bone marrow-derived circulating progenitor cells (BM-CPCs) are mobilized in adult peripheral blood (PB) during the acute myocardial infarction (AMI) period and contribute to the regeneration of infarcted myocardium. In this study, the influence of physical training on the mobilization and the migratory activity of the BM-CPCs as well as on the left ventricular function (LVEF) after AMI was examined. PATIENTS AND METHODS: 26 patients with AMI were analyzed in two groups. The first group comprised 17 patients with standardized exercise training for 3 weeks 14 +/- 4 days after AMI, the second group nine control subjects without exercise training. PB concentrations of CD34/45+ and CD133/45+ were measured by FACS. The migratory activity of BM-CPCs was analyzed by migration assay. B-type natriuretic peptide (BNP) in PB and the functional investigations spiroergometry (VO2 and PaO2) and stress echocardiography (LVEF) were determined in both groups. RESULTS: A significant increase in both concentrations, CD34/45+ and CD133/45+, as well as in migratory capacity of BM-CPCs was found after 3 weeks of exercise training, which was significantly decreased 3 months after completion of exercise training. No significant difference was observed in the control group without exercise training. In the functional investigations a significant increase in VO2 as well as PaO2 was shown spiroergometrically after exercise training. There was no difference in stress echocardiographic LVEF at rest in both groups. On the other hand, interestingly, the findings showed that the increase of LVEF at peak stress was significantly higher after exercise training as compared to the control group. Moreover, a significant decrease in BNP values was found after exercise training as well as 3 months after AMI. No difference was found in the control group. CONCLUSION: This study demonstrates that exercise training for 3 weeks after AMI leads to a significant mobilization as well as increase of functional activation of BM-CPCs in humans. Moreover, regular exercise training might contribute to the positive effects on the regenerative potency after AMI.

Aged↗

PubMed2005

Altered blood rheology in obstructive sleep apnea as a mediator of cardiovascular risk.

BACKGROUND: Cardiovascular complications are common in patients with obstructive sleep apnea (OSA). Blood rheology is a major determent of coagulation and an established risk factor for cardiovascular events. Since nocturnal hypoxemia could influence parameters of blood rheology, we hypothesized that OSA alters blood rheology independent of other cardiovascular risk factors. METHODS: One hundred and ten consecutive patients admitted to the sleep laboratory were included. The association of plasma fibrinogen and viscosity (as parameters of blood rheology) with OSA was evaluated. RESULTS: One hundred and ten patients aged 61.4+/-10.1 years (body mass index 28.4+/-4.1 kg/m2) were included. OSA was confirmed in 63 patients (57.2%) with an apnea-hypopnea index (AHI) of 28.7+/-14.9 events/hour. Patients with OSA showed higher levels of plasma viscosity (1.36+/-0.09 vs. 1.31+/-0.08 mPas, p=0.005). Nevertheless, hypertensive apneics have even higher levels of plasma viscosity than nonapneics (1.38+/-0.091 vs. 1.32+/-0.028 mPas, p=0.018). Similar results were found in patients with coronary artery disease, where OSA was associated with elevated plasma viscosity (1.36+/-0.076 vs. 1.31+/-0.081 mPas, p=0.007). Plasma fibrinogen was correlated with nocturnal minimal oxygen saturation (r=-0275, p=0.0036) and AHI (r=0.297, p=0.001). OSA was associated with higher plasma fibrinogen (353+/-83 vs. 317+/-62 mg/dl, p=0.015). These differences persist with control for cardiovascular risk factors. CONCLUSIONS: Patients with OSA have elevated morning fibrinogen levels and a higher plasma viscosity, which correlate positively with indices of sleep apnea severity. These changes in blood rheology are independent of cardiovascular risk factors, and therefore, might be specific mechanisms of OSA. This supports the pathophysiological concept that sleep apnea is a cardiovascular risk factor.

Adult↗

PubMed2005

[Hypertensive microvascular disease].

Arterial hypertension is a major cardiovascular risk factor and leads to vascular as well as to myocardial manifestations. Particularly hypertensive microvascular disease is of great importance. Major clinical manifestations of hypertensive heart disease are symptoms of coronary insufficiency with typical angina pectoris, but also heart failure (systolic or diastolic dysfunction) and arrhythmia. Different non-invasive and invasive procedures are available for screening. For ultimate quantitative assessment of the coronary reserve, invasive procedures are still required. Beside lowering blood pressure primary therapeutic target is to reverse cardiac manifestations of arterial hypertension using specific therapeutic algorithms.

Clinical Trials as Topic↗