Summer and autumnal activity patterns of juvenile and adult Dryomys nitedula were investigated in the wild using infrared motion sensor cameras. The study revealed that the forest dormouse is mainly crepuscular and nocturnal during the summer and autumn. Foraging activity started on average 8 min before sunset in June and shifted towards 26 min after sunset in September. The activity usually ended 40 min before sunrise independently of the season. The investigative activity around the nestboxes had three main periods: one between 20:00 and 22:00, one around midnight between 00:00 and 01:00, and a third one before sunrise between 4:00 and 6:00. Diurnal activity was also recorded but it occurred mainly in autumn and was restricted to the nestbox entrance; animals never switched nestboxes during the day if not disturbed. During the night activity, dormice used to investigate almost all nestboxes within their territory. However they showed preferences for only a few nestboxes which were used more frequently as daytime resting sites.
Circadian and circaannual oscillations of tissue lipid peroxides (LPO) were studied in young male Wistar rats. The concentration of malondialdehyde, one of LPO degradation products, was measured at 3-h intervals during 24 hours in rats, adapted to lightrdark 12:12 h regimen in the course of the year. LPO in the liver, thymus and bone marrow oscillated rhythmically in the course of the day and year. Circadian oscillations in all tissues were two-peaked, with zeniths at various times of the light and dark parts of the day. In the liver and thymus, the highest mesors were found during the winter, in the bone marrow during the spring. The same holds for amplitude values, with the exception of the bone marrow which exhibited the highest values during the summer. The reason for the LPO oscillations is probably resulting from the changing ratio of pro- and anti-oxidative capacities in various tissues during the day and the year.
Physiologically, leptin concentration is controlled by circadian rhythm. However, in critically ill patients, circadian rhythm is disrupted. Thus we hypothesized that circadian leptin concentration changes are not preserved in critically ill patients. Ten consecutive critically ill heart failure patients with the clinical indication for mechanical ventilation and sedation were included into our study. Plasma leptin concentration was measured every 4 h during the first day (0-24 h) and during the third day (48-72 h) after admission. During the first day, there were significant leptin concentration changes (ANOVA, p<0.05), characterized by an increase in concentration by 44 % (16-58 %); p=0.02 around noon (10 am-2 pm) and then a decrease in concentration by 7 % (1-27 %); p=0.04 in the morning (2 am-6 am). In contrast, there was no significant change in leptin concentration during the third day after admission (ANOVA, p=0.79). Based on our preliminary results, we concluded that in critically ill heart failure patients, the circadian rhythm of plasma leptin concentration seems to be preserved during the first but not during the third day after admission., I. Cundrle Jr., P. Suk, V. Sramek, Z. Lacinova, M. Haluzik., and Obsahuje bibliografii
The circadian system controls the timing of behavioral and physiological functions in most organisms studied. The review addresses the question of when and how the molecular clockwork underlying circadian oscillations within the central circadian clock in the suprachiasmatic nuclei of the hypothalamus (SCN) and the peripheral circadian clocks develops during ontogenesis. The current model of the molecular clockwork is summarized. The central SCN clock is viewed as a complex structure composed of a web of mutually synchronized individual oscillators. The importance of development of both the intracellular molecular clockwork as well as intercellular coupling for development of the formal properties of the circadian SCN clock is also highlighted. Recently, data has accumulated to demonstrate that synchronized molecular oscillations in the central and peripheral clocks develop gradually during ontogenesis and development extends into postnatal period. Synchronized molecular oscillations develop earlier in the SCN than in the peripheral clocks. A hypothesis is suggested that the immature clocks might be first driven by external entraining cues, and therefore, serve as “slave” oscillators. During ontogenesis, the clocks may gradually develop a complete set of molecular interlocked oscillations, i.e., the molecular clockwork, and become self-sustained clocks., A. Sumová, Z. Bendová, M. Sládek, R. El-Hennamy, K. Matějů, L. Polidarová, S. Sosniyenko, H. Illnerová., and Obsahuje bibliografii a bibliografické odkazy
We studied the circadian oscillation of lipid peroxides (TBARS) in the pineal gland of rats adapted to light:dark 12:12 h regimen. The concentration of TBARS was determined at 3-h intervals during 24 hours. TBARS of pineal gland oscillated rhytmically during the 24 h period. The maximal concentration of lipoperoxidative products was found at 20.00 h and 02.00 h and the lowest values at 08.00 h and 23.00 h. The determination of antioxidant capacity is needed for explaining the mechanism of TBARS oscillations in the pineal gland.