The circadian body temperature rhythm in the elderly: effect of single daily melatonin dosing.

The present study is part of a more extensive investigation dedicated to the study and treatment of age-dependent changes/disturbances in the circadian system in humans. It was performed in the Tyumen Elderly Veteran House and included 97 subjects of both genders, ranging from 63 to 91 yrs of age. They lived a self-chosen sleep-wake regimen to suit their personal convenience. The experiment lasted 3 wks. After 1 control week, part of the group (n=63) received 1.5 mg melatonin (Melaxen) daily at 22:30 h for 2 wks. The other 34 subjects were given placebo. Axillary temperature was measured using calibrated mercury thermometers at 03:00, 08:00, 11:00, 14:00, 17:00, and 23:00 h each of the first and third week. Specially trained personnel took the measurements, avoiding disturbing the sleep of the subjects. To evaluate age-dependent changes, data obtained under similar conditions on 58 young adults (both genders, 17 to 39 yrs of age) were used. Rhythm characteristics were estimated by means of cosinor analyses, and intra- and inter-individual variability by analysis of variance (ANOVA). In both age groups, the body temperature underwent daily changes. The MESOR (36.38+/-0.19 degrees C vs. 36.17+/-0.21 degrees C) and circadian amplitude (0.33+/-0.01 degrees C vs. 0.26+/-0.01 degrees C) were slightly decreased in the elderly compared to the young adult subjects (p<0.001). The mean circadian acrophase was similar in both age groups (17.19+/-1.66 vs. 16.93+/-3.08 h). However, the inter-individual differences were higher in the older group, with individual values varying between 10:00 and 23:00 h. It was mainly this phase variability that caused a decrease in the inter-daily rhythm stability and lower group amplitude. With melatonin treatment, the MESOR was lower by 0.1 degrees C and the amplitude increased to 0.34+/-0.01 degrees C, a similar value to that found in young adults. This was probably due to the increase of the inter-daily rhythm stability. The mean acrophase did not change (16.93 vs. 16.75 h), although the inter-individual variability decreased considerably. The corresponding standard deviations (SD) of the group acrophases were 3.08 and 1.51 h (p<0.01). A highly significant correlation between the acrophase before treatment and the phase change under melatonin treatment indicates that this is due to a synchronizing effect of melatonin. Apart from the difference in MESOR, the body temperature rhythm in the elderly subjects undergoing melatonin treatment was not significantly different from that of young adults. The data clearly show that age-dependent changes mainly concern rhythm stability and synchronization with the 24 h day. A single daily melatonin dose stabilizes/synchronizes the body temperature rhythm, most probably via hypothermic and sleep-improving effects.

[Characteristics of circadian rhythms of arterial pressure and heart rate in hypertensive subjects living in the North of the Tiumen' region]. / Osobennosti tsirkadiannykh ritmov arterial'nogo davleniia i chastoty serdechnykh sokrashchenii u bol'nykh arterial'noi gipertoniei, postoianno prozhivaiushchikh v usloviiakh Tiumenskogo Pripoliar'ia.

Chronostructure of arterial pressure (AP) and heart rate (HR) was studied in 62 residents of Tumen Region North with arterial hypertension (AH) aged 18-50 years and 56 AH controls living in the temperate zone. The groups were matched by age, sex, AH duration, office systolic and diastolic arterial pressure (SAP and DAP, respectively). Circadian AP profile with night hypertension was registered in 76.6 and 28.3% patients of the test and control groups, respectively. Test group patients had more pronounced defects in DAP and HR chronostructures. Thus, AH patients living in the Tumen North demonstrate abnormal circadian AP profile and AP and HR chronostructure. This may be prognostically important for development of cardiovascular complications.

[Chronological structure of arterial pressure in hypertensive patients on enalapril]. / Khronostruktura arterial'nogo davleniia u bol'nykh gipertonicheskoi bolezn'iu na fone terapii énalaprilom.

34 male patients with hypertension stage I and II aged 29-52 years (mean age 40.9 +/- 6.00) having mean 24-h arterial pressure (AP) above 135/85 mm Hg in mean daytime AP above 140/90 mm Hg and heart rate maximum 80 b/m entered the study of AP chronostructure in conditions of pure background and on enalapril treatment week 4, 8 and 12. The initial dose of the drug was 5 mg. Dose selection was controlled by 24-h AP monitoring. Enalapril was shown to significantly reduce mean daytime and 24-h AP as well as hyperbaric index, chronobiological time index, variability of systolic AP. The above dose selection brought more balanced AP lowering at daytime and at night. After 11 weeks of treatment no night-peakers were registered, the number of over-dippers decreased. Circadian rhythm of some hemodynamic parameters was characterized by a significant fall of rhythm average in unchanged acrophase and circadian AP amplitude indicating physiological action of enalapril.

The cosmos and CHAT, prompting blood pressure and heart rate monitoring for Dérer's week.

BACKGROUND: The effects of natural environmental factors upon health, documented in Minnesota, support the proposition of Bratislava's champions of the cosmos and of the biological week, gauged via circaseptan rhythms by the late Ladislav Dérer, whose "macro-rhythm" lasted "most frequently about 6 days". MAIN PURPOSE: To introduce 7-day monitoring of blood pressure and heart rate into routine practice. STARTING POINTS AND METHODS: Cosinor analysis on 7-day series determines (conventionally ignored) consistent blood pressure overswinging, i.e., circadian hyper-amplitude-tension (CHAT), a disease risk syndrome, whether it is associated with a normal average blood pressure or a high blood pressure. RESULTS: Summary of information understandable by the general population on the dynamics of blood pressure. CONCLUSIONS AND MEANING FOR PRACTICE AND THEORY: Space weather reports may prompt preventive measures. Caution dictates in any event monitoring blood pressure and heart rate for 7 days to attempt to prevent strokes, rather than to ignore the greatest yet detectable risk of catastrophic vascular disease, CHAT, a risk greater than old age or high blood pressure. (Tab. 1, Fig. 3, Ref. 31.)

[Changes in the circadian biorhythms in animal and human ontogeny]. / Issledovanie izmenenii tsirkadiannykh bioritmov v ontogeneze zhivotnykh i cheloveka.

It has been demonstrated that from the early stages of postnatal life up to adult age, gradual development of circadian amplitudes invariably takes place which may lead up to a complete absence of the diurnal rhythm in senile organisms. These changes are observed at various levels of organization of homeostatic systems (from cellular to organismic ones). A discussion is made of a possibility of evaluation of the level of adaptability and reliability of biological systems, as well as of their functional optimum via the analysis of circadian organization in ontogenesis, including gerontological problems (differentiation into age periods, biological age).

[Dynamics of some carbohydrate metabolic indices in the liver and the alcohol concentration in it depending on the time of day of its administration]. / Dinamika nekotorykh pokazatelei uglevodnogo obmena v pecheni i kontsentratsiia v nei alkogolia v zavisimosti ot vremeni cutok ego vvedeniia

The liver glycogen and sugar levels in intact rats are shown to experience diuranal variations with a maximum at 3-9 and minimum at 15-21 hours. Intragastric administration of ethanol in a dose of 1.5 ml/100 g produced an abrupt fall of the glycogen content in the liver of rats in 3.12 and maximally after a lapse of 6 hours, this being followed by a drop in the amount of sugar in 12 hours. The decline in the level of metabolites at different periods of the day (3, 9, 15 and 21 hr) was dissimilar. The lethality among the animals and concentration of the alcohol in the liver 3 and 6 hours following the action of alcohol at the hours of the day under study correlated and were inversely proportional to the sugar and glycogen content of the same hours of the day.