Mechanisms underlying atrial fibrillation (AF), the most common cardiac arrhythmia, particularly in aged population, are not fully elucidated. We have previously shown an increased propensity of old guinea pigs (GPs) heart to inducible AF when comparing to young animals. This study aimed to verify our hypothesis that susceptibility of aged heart to AF may be attributed to abnormalities in myocardial connexin-43 (Cx43) and extracellular matrix that affect cardiac electrical properties. Experiments were conducted on male and female 4-week-old and 24-week-old GPs. Atrial tissue was processed for analysis of Cx43 topology using immunohistochemistry, expression of Cx43 protein using immunobloting, and expression of mRNA of Cx43 and extracellular matrix metalloproteinase-2 (MMP-2) using real time PCR. Immunohistochemistry revealed uniform Cx43 distribution predominantly on lateral sides of the cardiomyocytes of young male and female GP atria. In contrast, non-uniform distribution, mislocalization and reduced immunolabeling of Cx43 were detected in atria of old GPs. In parallel, the atrial tissue levels of Cx43 mRNA were significantly decreased, while mRNA expression of MMP-2 was significantly increased in old versus young GPs. The changes were more pronounced in old GPs males comparing to females. Findings indicate that age-related down-regulation of atrial Cx43 and up-regulation of MMP-2 as well as disordered Cx43 distribution can facilitate development of AF in old guinea pig hearts., V. Nagibin, T. Egan Benova, C. Viczenczova, B. Szeiffova Bacova, I. Dovinova, M. Barancik, N. Tribulova., and Obsahuje bibliografii
a1_Cíle. Cílem výzkumu bylo popsat výskyt specifických forem násilného chování dospívajících ve škole a analyzovat rodinný, vrstevnický a školní kontext agresivního chování. Soubor a metoda. Soubor tvořili dospívající ze 115 náhodně vybraných základních škol. Dotazováni byli žáci 7., 8. a 9. ročníku, z každé školy se účastnila jedna třída. Informace byly získávány prostřednictvím dotazníku, který zahrnoval položky týkající se projevů agresivního chování a jeho kontextu, dále položky mapující vztah k rodině, vrstevníkům, škole a učitelům. Výzkum proběhl metodou on-line aplikace přes internetové rozhraní. Soubor tvořilo 3 165 žáků, průměrný věk byl 13,9 let (SD = 0,97). Chlapci tvořili 52,3 % souboru. Výzkumné otázky. Výzkum měl explorační charakter a kladl si tyto výzkumné otázky: jaký je výskyt různých projevů agresivního chování mezi dospívajícími, jaká je souvislost mezi vybranými proměnnými z oblasti rodiny, vrstevnických vztahů a vztahů ke škole a úrovní agresivního chování. Statistická analýza. Základní popisná statistika byla použita pro prezentaci výskytu projevů násilného chování, kontextové vztahy byly analyzovány chí-kvadrát testem a aplikací multinomiální logistické regrese. Výsledky. Věcně významný výskyt (tj. častěji než pětkrát za posledních 12 měsíců) projevů agresivního chování byl v případě verbální agrese 16,6 %, fyzické agrese 7,5 % a vandalismu 3,1 %. Na základě charakteristik kompozitní proměnné byly vytvořeny tři skupiny: 1) dospívající s nízkou nebo průměrnou úrovní agresivního chování, 2) dospívající se zvýšenou úrovní agresivního chování a 3) dospívající s vysokou úrovní agresivního chování., a2_V multinomiální logistické regresi se jako statisticky významné prediktory agresivního chování uplatnily následující proměnné: dobrý vztah k matce a otci (oba negativně), používání tělesného trestání v rodině, oblíbenost mezi vrstevníky (negativně), časté trávení času s partou rovnou po škole a o víkendech, spravedlivé jednání učitelů (negativně), stresující charakter školy, neoblíbenost školního prostředí a přílišná očekávání ze strany učitelů. Silným prediktorem agresivního chování je mužské pohlaví. Omezení studie. Omezení studie vyplývají z průřezového designu a metody založené na self-reportech., b1_Objectives. The major goal of the study was to describe the prevalence of specific forms of violent behaviour of adolescents in elementary schools and to analyse family, peer and school context of aggressive behaviour. Subjects and methods. The sample consisted of adolescents from 115 randomly selected elementary schools. Schoolchildren from grades 7th, 8th and 9th were asked to fill in the on-line questionnaire via web access. The items of the questionnaire covered the topic of aggressive behaviour and its context, relationships within the family, relationships towards peers, school and teachers. In sum 3,165 students participated, the mean age was 13.9 years (SD = 0.97). Boys accounted for 52.3% of the sample. Research questions. The exploratory study focused on two research questions: how frequently occur various forms of aggression in adolescents, and what is the role of family, peer and school-related factors in aggressive behaviour. Statistical analysis. Descriptive statistics and chi2 test were used to analyse the occurrence of violent behaviour; contextual relationships were analysed by application of multinomial logistic regression. Results. Substantively significant occurrence (more than five times in the last 12 months) of aggressive behaviour was reported as follows: verbal aggression 16.6%, physical aggression 7.5%, and vandalism to school property 3.1%. Based on the distribution of the composite variable three groups of adolescents were created: 1) with low or moderate level, 2) with increased level and a 3) with high level of aggressive behaviour. In multinomial logistic regression the following variables had statistically significant effect on dependent variable (aggressive behaviour):, b2_a good relationship with mother and father (both negatively), the use of physical punishment in the family, sociability/popularity (negatively), frequently spending time with peers straight after school and on weekends, treated fairly by teachers (negatively), stressful nature of the school, the unpopularity of the school environment and excessive expectations from teachers. Male gender was found as a strong predictor of aggressive behaviour as well. Study limitations. Limitations of the study result from the cross-sectional design and data based on self-reports., Ladislav Csémy ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
Článek podrobně popisuje autorovo neobvyklé setkání s kojoty (Canis latrans) v roce 2010 v kostarickém národním parku Braulio Carillio v části Sector Volcán Barva. Pořízené dokumentační fotografie umožnily analyzovat agresivní chování kojotů vůči člověku a jeho etologickou interpretaci na základě znalostí etologie psovitých šelem., In August 2010, the author visited Braulio Carrillo National Park in Costa Rica and approached three coyotes (Canis latrans). The article describes their attack, probably due to maternal aggression combined with fear-induced and territorial aggressions., and Ivan Literák.
Agrolesnické systémy v tropických oblastech nabízejí možnost, jak zajistit trvale udržitelnou produkci na obdělávaných pozemcích, a často představují jediný zalesněný ekosystém v okolní odlesněné krajině. Tento článek se věnuje problematice agrolesnictví v tropech se zaměřením na kávové plantáže pěstované v Peru., Agroforestry systems present a way to keep sustainable production in cultivated areas, especially in the tropical zone. At the same time it is often the only forested ecosystem in otherwise deforested landscape. This article is about agroforestry in tropical areas, with the focus on coffee (Coffea) plantations in Peru., and Lenka Ehrenbergerová.
The requirements of conservators who take care of historical monuments are that the materials for rehabilitation of old renders should have a composition as similar to the historical materials as possible and should provide improvement in durability. Fine and coarse sepiolite and synthetic zeolite pellets were chosen as additives in the development of lime mortars for conservation work, due to their unique adsorption properties providing water to the mortar system and acting as water reservoirs in conditions of low humidity. Flexural and compressive strength and the dynamic modulus of elasticity were studied at 28, 90 and 180 days of curing. Addition of both fine and coarse sepiolite and zeolite pellets caused improvement of mechanical strength of mortars, clearly evident at later ages of curing. Elasticity modulus ranged from 2.3 GPa to 3.6 GPa relating to a high deformation capability of mortars and confirming their suitability for use in conservation work., Slávka Andrejkovičová, Eduardo Ferraz, Ana L. Velosa, António S. Silva and Fernando Rocha., and Obsahuje bibliografii
Chronic airflow limitation, caused by chronic obstructive pulmonary disease (COPD) or by asthma, is believed to change the shape and the position of the diaphragm due to an increase in lung volume. We have made a comparison of magnetic resonance imaging (MRI) of diaphragm in supine position with pulmonary functions, respiratory muscle function and exercise tolerance. We have studied the differences between patients with COPD, patients with asthma, and healthy subjects. Most interestingly we found the lung hyperinflation leads to the changes in diaphragmatic excursions during the breathing cycle, seen in the differences between the maxim al expiratory diaphragm position (DPex) in patients with COPD and control group (p=0.0016) . The magnitude of the diaphragmatic dysfunction was significantly related to the airflow limitation expressed by the ratio of forced expiratory volume in 1 s to slow vital capacity (FEV 1 /SVC) , (%, p=0.0007); to the lung hyperinflation expressed as the ratio of the residual volume to total lung capacity (RV/TLC), (%, p=0.0018) and the extent of tidal volume constrain expressed as maximal tidal volume (V Tmax ), ([l], p=0 .0002); and the ratio of tidal volume to slow vital capacity (VT/SVC), (p=0.0038) during submaximal exercise. These results suggest that diaphragmatic movement fails to contribute sufficiently to the change in lung volume in emphysema. Tests of respiratory muscle function were related to the position of the diaphragm in deep expiration, e.g. neuromuscular coupling (P 0.1 /VT) (p=0.0232). The results have shown that the lung volumes determine the position of the diaphragm and function of the respiratory muscles. Chronic airflow limitation seems to change the position of the diaphragm, which thereafter influences inspiratory muscle function and exercise tolerance. There is an apparent relationship between the position of the diaphragm and the pulmonary functions and exercise tolerance., L. Hellebrandová, J. Chlumský, P. Vostatek, D. Novák, Z. Rýznarová, V. Bunc., and Obsahuje bibliografii