Chronický tinnitus je běžná porucha vyskytující se s prevalencí vyšší než 8 % v populaci starší 50 let, je velmi obtížně léčitelná a narušuje plnohodnotný život postiženého jedince. Tinnitus bývá poměrně často spojen s hluchotou a zdá se, že může být výsledkem patologických neuroplastických procesů v mozkové kůře. Neurozobrazovací studie ukazují na zvýšenou aktivitu v primárním sluchovém kortexu. Transkraniální magnetická stimulace (TMS) je nová a neinvazivní metoda, využívající elektromagnetických principů. TMS je schopna modulovat excitabilitu povrchových vrstev mozkové kůry. Stimulační efekt se šíří i do funkčně spojených vzdálených oblastí mozku. TMS byla již úspěšně užívána u jiných poruch spojených se zvýšenou aktivitou mozkové kůry. Bylo dokázáno, že nízkofrekvenční repetitivní transkraniální magnetická stimulace (rTMS) může být efektivní v terapii poruch provázených změnou excitability mozkové kůry, jako jsou auditivní halucinace. Současné teoretické podklady a první klinické studie nasvědčují tomu, že TMS by mohla mít v léčbě chronického tinnitu dobrý léčebný potenciál. Zřejmá je zde nutnost dalšího výzkumu s větším množstvím pacientů, jak v oblasti klinické, tak v doplnění neurobiologického základu změn vyvolaných TMS., Chronic tinnitus is a frequent and often severely disabling disorder with a prevalence of over 8 % in subjects over 50 years. Tinnitus disrupts the full-value life of the patient and it is difficult to treat . The disorder is frequently associated with hearing loss and may be the result of neuroplastic alterations within the brain. Neuroimaging studies demonstrate increased activity within the central auditory system. TMS is a non-invasive method uses electromagnetic principles. TMS allows to modulate the excitability within superficial cortical areas. Stimulation effects can propagate also to functionally connected remote brain areas. It has been successfully employed in the treatment of other conditions associated with increased activity of the cerebral cortex. Applied as low frequency rTMS it has been proven to be effective for the treatment of disorders which are associated with focal hyperexcitability such as auditory hallucinations. There is a good theoretical basis and increasing research evidence suggesting a potential of TMS for the treatment of tinnitus. Further studies with large sample sizes and additional assessment of neurobiological effects are needed. Within this paper we discuss the potential for TMS as a therapy of tinnitus., Jana Dvořáková, M. Anders, Ivo Paclt, J. Raboch, M. Holcát, L. Rathová, B. Langguth, and Lit. 27
A simple replication theory of coevolution of genes and memes is
proposed. A population composed of couples of genes and memes, the so-called m-genes, is subjected to Darwinian evolution. Three diíferent types of operations over m-genes are introduced: Replication (an m-gene is replicated with mutations onto an offspring m-gene), interaction (a memetic transfer from a donor to an acceptor), and extinction (an m-gene is eliminated). Computer simulations of the present model allow us to identify diíferent mechanisms of gene and meme coevolutions.
T wave morphology (TWM) descriptors derived from Holter electrocardiograms during hemodialysis (HD) are of potential value for cardiac risk assessment in HD patients. Our knowledge on autonomic regulation of TWM descriptors is limited. The purpose of this study was to investigate the association between TWM parameters and heart rate variability (HRV) during intradialytic monitoring. In each of 81 patients on maintenance HD, continuous electrocardiograms were recorded 5 times during HD on alternate weeks. TWM descriptors were calculated every 5 s in overlapping 10-s ECG segments and Low Frequency (LF) (0.04 Hz to 0.15 Hz), High Frequency (HF) (0.15 Hz to 0.40 Hz) powers of the spectrum of HRV were calculated every five min. The calculated values of TWM and HRV were averaged during the first hour of the recordings and subsequently over all recordings in each subject. Analyzable data for HRV and TWM were available in 71 HD patients (aged 61±15, 36 % diabetics, 32 % females). LF in normalized units correlated positively with Total Cosine R to T (r=0.374, p=0.001) and negatively with T wave morphology dispersion (r=-0.253, p=0.033) after adjusting for heart rate. A heart rate independent association between repolarisation descriptors and HRV exists in HD patients. Autonomic modulation needs to be considered when using TWM characteristics for risk profiling of HD patients., D. Poulikakos, D. Banerjee, M. Malik., and Obsahuje bibliografii
The aim of our study was to assess if repolarization BSPM were able to evaluate the site, size and severity of chronic ischaemic damages and if BSPM were in any way related to the regional attenuation of myocardial contractility or to the site of coronary artery occlusion. The BSPM were obtained from 69 patients suffering from coronary artery disease confirmed by coronarography, with at least 75 % occlusion of at least one coronary artery. According to the site of single occlusion, or a combination of the sites of multiple occlusions, the patients were divided into 6 subgroups. According to the region of attenuated kinetics the same group of 69 patients was also divided into other 6 subgroups. As in the polarity distribution there was only a limited accordance in BSPM with coronarographie and échocardiographie Findings, in the localization of extreme values there were very important specific changes in patients with normal kinetics as determined by both contrast ventriculography and two-dimensional echocardiography. The repolarization maps can distinguish patients with coronary artery disease and normal echocardiography from healthy persons with a sensitivity of 85 % and a specificity of 65 % in the case of the isoareal map from the ST segment (R1AM) and 90 % and 85 %, respectively, in the case of the isointegral map from the whole ST-T segments (R1IM).