Cardiac autonomic activity during sleep in high-altitude resident children compared with lowland residents

Study Objectives We aimed to characterize heart-rate variability (HRV) during sleep in Andean children native to high altitude (HA) compared with age, gender, and genetic ancestry-similar low-altitude (LA) children. We hypothesized that the hypoxic burden of sleep at HA could induce variation in HRV. As children have otherwise healthy cardiovascular systems, such alterations could provide early markers of later cardiovascular disease. Methods Twenty-six LA (14F) and 18 HA (8F) children underwent a single night of attended polysomnography. Sleep parameters and HRV indices were measured. Linear mixed models were used to assess HRV differences across sleep stage and altitude group. Results All children showed marked fluctuations in HRV parameters across sleep stages, with higher vagal activity during nonrapid eye movement sleep and greater variability of the heart rate during rapid eye movement (REM). Moreover, HA children showed higher very low-frequency HRV in REM sleep and, after adjusting for heart rate, higher low-to-high frequency ratio in REM sleep compared with children living at lower altitude. Conclusions We confirmed previous findings of a stage-dependent modulation of HRV in Andean children living at both HA and LA. Moreover, we showed subtle alteration of HRV in sleep in HA children, with intriguing differences in the very low-frequency domain during REM sleep. Whether these differences are the results of an adaptation to high-altitude living, or an indirect effect of differences in oxyhemoglobin saturation remains unclear, and further research is required to address these questions

Development of the use of the decimal classification in the Czech ambient

Cílem bakalářské práce je shrnutí vývoje a využití desetitmého třídění v českých knihovnách a jiných informačních institucích. V práci jsou nejprve popsány hlavní rozdíly mezi nejvýznamnějšími pořádacími systematyckými jazyky: Deweyho desetinném třídění, Mezinárodním desetinném tříděním a Tříděním Kongresové knihovny. Hlavní důraz je kladen na podání jejich charakteristiky a popsání jejich struktury. Pozornost je zejména věnována prvním pokusům o zavedení desetinného třídění v českém prostředí -je zde uveden výčet nejvýznamnějších osobnosti, které se u nás ponejvíce zasloužily o propagaci a rozšiřování věcného pořádání informací. V navazujících částech jsou popsány snahy o všeobecné zavedení tabulek a pokusy o jejich příslušná vydání. Na něž navazuje modifikace desetinného třídění L. N. Tropovského a následující vydání Tabulek desetinného třídění ÚTEINu a dále tvorba oborových a odvětvových výtahů. Poslední část je věnována pokusům o vydání úplných československých tabulek. V závěru je shrnut celkový přínos desetinného třídění pro české země.Ústav informačních studií a knihovnictvíInstitute of Information Studies and LibrarianshipFaculty of ArtsFilozofická fakult

Adaptation to life in the High Andes: nocturnal oxyhemoglobin saturation in early development

Study objectives: physiological adaptation to high altitude hypoxia may be impaired in Andeans with significant European ancestry. The respiratory ‘burden’ of sleep may challenge adaptation, leading to relative nocturnal hypoxia. Developmental aspects of sleep-related breathing in high-altitude native children have not previously been reported. We aimed to determine the influence of development on diurnal-nocturnal oxyhemoglobin differences in children living at high altitude.Methods: this was a cross-sectional, observational study. Seventy-five healthy Bolivian children aged 6 mo to 17 y, native to low altitude (500 m), moderate high altitude (2,500 m), and high altitude (3,700 m) were recruited. Daytime resting pulse oximetry was compared to overnight recordings using Masimo radical oximeters. Genetic ancestry was determined from DNA samples.Results: children had mixed European/Amerindian ancestry, with no significant differences between altitudes. Sixty-two participants had ? 5 h of nocturnal, artifact-free data. As predicted, diurnal mean oxyhemoglobin saturation decreased across altitudes (infants and children, both P < 0.001), with lowest diurnal values at high altitude in infants. At high altitude, there was a greater drop in nocturnal mean oxyhemoglobin saturation (infants, P < 0.001; children, P = 0.039) and an increase in variability (all P ? 0.001) compared to low altitude. Importantly, diurnal to nocturnal altitude differences diminished (P = 0.036), from infancy to childhood, with no further change during adolescence.Conclusions: physiological adaptation to high-altitude living in native Andeans is unlikely to compensate for the significant differences we observed between diurnal and nocturnal oxyhemoglobin saturation, most marked in infancy. This vulnerability to sleep-related hypoxia in early childhood has potential lifespan implications. Future studies should characterize the sleep- related respiratory physiology underpinning our observation