Ivo Ponocny

Endurance Exercise Training in Orthostatic Intolerance A Randomized, Controlled Trial

Orthostatic intolerance is a syndrome characterized by chronic orthostatic symptoms of light-headedness, fatigue, nausea, orthostatic tachycardia, and aggravated norepinephrine levels while standing. The aim of this study was to assess the protective effect of exercise endurance training on orthostatic symptoms and to examine its usefulness in the treatment of orthostatic intolerance. 2768 military recruits were screened for orthostatic intolerance by questionnaire. Tilt-table testing identified 36 cases of orthostatic intolerance out of the 2768 soldiers. Subsequently, 31 of these subjects with orthostatic intolerance entered a randomized, controlled trial. The patients were allocated randomly to either a “training” (3 months jogging) or a “control” group. The influence of exercise training on orthostatic intolerance was assessed by determination of questionnaire scores and tilt-table testing before and after intervention. After training, only 6 individuals of 16 still had orthostatic intolerance compared with 10 of 11 in the control group. The Fisher exact test showed a highly significant difference in diagnosis between the 2 groups (P=0.008) at the end of the study. Analysis of the questionnaire-score showed significant interaction between time and group (P=0.001). The trained subjects showed an improvement in the average symptom score from 1.79±0.4 to 1.04±0.4, whereas the control subjects showed no significant change in average symptom score (2.09±0.6 and 2.14±0.5, respectively). Our data demonstrate that endurance exercise training leads to an improvement of symptoms in the majority of patients with orthostatic intolerance. Therefore, we suggest that endurance training should be considered in the treatment of orthostatic intolerance patients.

A meta-analysis for neurobehavioural effects due to electromagnetic field exposure emitted by GSM mobile phones

Background and objective: Numerous studies have investigated the potential effects of electromagnetic fields (EMFs) emitted by GSM mobile phones (∼900 MHz to ∼1800 MHz) on cognitive functioning, but results have been equivocal. In order to try and clarify this issue, the current study carried out a meta-analysis on 19 experimental studies. Design: Meta-analysis. Methods: Nineteen studies were taken into consideration. Ten of them were included in the meta-analysis as they fulfilled several minimum requirements; for example, single-blind or double-blind experimental study design and documentation of means and standard deviation of the dependent variables. The meta-analysis compared exposed with non-exposed subjects assuming that there is a common population effect so that one single effect size could be calculated. When homogeneity for single effect sizes was not given, an own population effect for each study and a distribution of population effects was assumed. Results: Attention measured by the subtraction task seems to be affected in regard to decreased reaction time. Working memory measured by the N-back test seems to be affected too: under condition 0-back target response time is lower under exposure, while under condition 2-back target response time increases. The number of errors under condition 2-back non-targets appears to be higher under exposure. Conclusion: Results of the meta-analysis suggest that EMFs may have a small impact on human attention and working memory.

No effects of short-term exposure to mobile phone electromagnetic fields on human cognitive performance: a meta-analysis.

During recent years, a large number of studies on the effects of electromagnetic fields emitted by cellular mobile phones on human cognitive performance have been carried out. However, the results have been ambiguous. We carried out the current meta-analysis in order to investigate the impact of electromagnetic fields emitted by mobile phones on human cognition. Seventeen studies were included in the meta-analysis as they fulfill several requirements such as single- or double-blind experimental study design, and documentation of means and standard deviations of dependent variables. The meta-analysis was carried out as a group comparison between exposed and non-exposed subjects. No significant effects of electromagnetic fields emitted by Global System for Mobile Communications (GSM) and Universal Mobile Telecommunications System (UMTS) mobile phones were found. Cognitive abilities seem to be neither impaired nor facilitated. Results of the meta-analysis suggest that a substantial short-term impact of high frequency electromagnetic fields emitted by mobile phones on cognitive performance can essentially be ruled out.

Influence of an Insertion Variant in the 5ʹUTR of the Endothelin-1 Gene on Orthostatic Intolerance

Background:Orthostatic intolerance is a multifactorial disease in which the genetic contribution is probably the result of a number of genes acting in combination. Recent work has shown that orthostatic intolerance is influenced by endothelial nitric oxide synthase gene polymorphisms. Since endothelin-1 (ET-1) is one of the most important vasoconstrictor peptides, a frequent adenine insertion polymorphism within the 5′-untranslated region (5′UTR), which is of functional importance for ET-1 expression, could influence orthostatic intolerance. The aim of this study was therefore to ascertain whether this frequent variant of the endothelin-1 gene influences the risk for orthostatic intolerance. Methods:We studied 257 white patients (120 cases with orthostatic intolerance and 137 controls) for genotyping of the 5′UTR I variant. From this cohort, 111 patients and 99 control subjects underwent a tilt-table test or an upright posture study, including monitoring of blood pressure, heart rate, and plasma catecholamines, in the supine position and during 30 minutes of standing. Genotyping was performed in all participants. &khgr;2 tests of independence were used to test for associations between orthostatic intolerance and genotype. In addition, an association of the insertion polymorphism with hemodynamic variables (heart rate, supine and upright blood pressure) was ascertained using one-way analysis of variance. Results:The 5′UTR I variant was significantly less common in patients with orthostatic intolerance (allele frequency 0.36 and 0.28, in controls and cases, respectively). Additionally, we found a significant decrease in the risk of orthostatic intolerance among people who were homozygous for the 5′UTR variant (I/I) compared with the wild-type variant (D/D) (odds ratio, 0.41; 95% confidence interval, 0.17 to 0.97; P = 0.04). No association between the 5′UTR variant and heart rate or blood pressure regardless of diagnosis was found. Conclusions:Our current results suggest that the hereditary adenine insertion variant in the 5′-UTR of the endothelin-1 gene is protective for orthostatic intolerance. The increased ET-1 protein expression that has been linked with the I variant might be associated with a more efficient hemodynamic response to standing. This is likely one of several common genetic loci that may represent modifiers of orthostatic intolerance phenotypes.

Mobile phone base stations and well-being--A meta-analysis.

It is unclear whether electromagnetic fields emitted by mobile phone base stations affect well-being in adults. The existing studies on this topic are highly inconsistent. In the current paper we attempt to clarify this question by carrying out a meta-analysis which is based on the results of 17 studies. Double-blind studies found no effects on human well-being. By contrast, field or unblinded studies clearly showed that there were indeed effects. This provides evidence that at least some effects are based on a nocebo effect. Whether there is an influence of electromagnetic fields emitted by mobile phone base stations thus depends on a persons knowledge about the presence of the presumed cause. Taken together, the results of the meta-analysis show that the effects of mobile phone base stations seem to be rather unlikely. However, nocebo effects occur.