[Seasonal and circadian fluctuations in blood biochemical indicators in mice in natural conditions and exposed to constant light]. / Sezonnye i sutochnye kolebaniia biokhimicheskikh pokazatelei krovi u myshei v estestvennykh usloviiakh i pri postoiannom osveshchenii.

The fluctuations of activity of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) and those of the levels of protein, glucose, cholesterol, bilirubin, creatinine, blood urea nitrogen, K+, Cl-, Na+ in blood plasma of mice in natural conditions (NC) and exposed to constant light (CL) were studied in different seasons of the year (in January, April, July, October) on days 18, 24, 6 (at 12 o'clock). Most indices both in NC and CL animals had seasonal rhythm similar for each of them. This proves a primary effect of environmental geoclimatic factors of formation of circadian periodicals as compared to desynchronization in constant light revealed by Kosinor analysis in winter (acrophase from 14.16 till 16.32 o'clock) and autumn (acrophase from 23.03 til 4.40 o'clock). During the same seasons one can observe the maximum desynchronization influences of constant light, which leads to abrupt falling (to the 10-fold and more) of the fluctuations amplitude and in some cases to stabilization of circadian rhythm.

[Diurnal rhythm of rectal temperature in mice during various lighting conditions]. / Sutochnyi ritm rektal'noi temperatury u myshei pri razlichnom fotorezhime.

The study of circadian rhythm of rectal temperature (t degrees) during 4.5 months in mice under conditions of continuous lighting (LL) and natural alteration of day and night (LD), considering astronomic time of sunrise and sunset, revealed the following regularities: In winter and in summer t degrees maximum in LD was marked at the beginning of the dark period of time (twilight period), t degrees minimum was observed at the end of the dark period. In winter, when the dark period lasts 14-15 hours, t degrees falls from maximum to minimum during all the dark period (12-14 hours), and in summer, when the period of darkness lasts 6 hours, t degrees falls only during 2 hours. In spring t degrees minimum shifts to the middle of the light period. Under conditions of LL, circadian rhythm of t degrees "splits" periodically into bimodal with periods of 10-14 hours. Long keeping (during 4.5 months) under conditions of LL results in levelling of t degrees circadian rhythm. The character of t degrees circadian rhythm in laboratory animals (mice) is not inverted to that in human beings.

[Seasonal and circadian fluctuations of the biochemical indices of the blood in mice]. / Sezonnye i sutochnye kolebaniia biokhimicheskikh pokazatelei krovi u myshei.

Seasonal (in January, April, July, October) changes of aspartate aminotransferase (AST), alanine aminotransferase (ALT), protein, bilirubin, glucose, cholesterol, creatinine, blood urea nitrogen, Cl-, K+, Na+ content were studied in the blood plasma of mice at different time of day (6 p. m., midnight, 6 a. m., midday). The analysis of the average daily indices has shown that the most expressed variations were the following: AST (spring maximum is 3.7 times higher than autumn minimum), ALT (winter maximum is 2.9 times higher than autumn minimum), creatinine (summer maximum is 2.5 times higher than winter minimum), blood urea nitrogen (summer maximum is 2.5 times higher than autumn minimum). Bilirubin and protein content in spring is insignificant, but it is significantly higher than in other seasons. Cholesterol content is lower in winter. No differences in glucose, Cl-, K+, Na+ content in different months have been revealed. The largest circadian synchronization was observed in winter in AST, glucose, cholesterol, protein, Cl-, K+, Na+ (the level observed at 6 p. m. and at midday is higher than that observed at midnight and 6 a. m.) and in autumn in AST, ALT, glucose, cholesterol, blood urea nitrogen, with the circadian curves inverse as compared to the winter period. In spring practically no circadian synchronization was observed.

[Chronosensitivity to absolute hypercapnia in various light regimens]. / Khronochuvstvitel'nost' k absoliutnoi giperkapnii pri razlichnom svetovom rezhime.

The studies of mice on the natural regimen of day and night alterations have revealed a daily rhythm of hypercapnia toxicity, with the maximum sensitivity observed at 6 a.m. and the minimum sensitivity at 6 p.m.-2 a.m. and 2 p.m.-6 p.m. The experiments on animals kept for 2 weeks-1 month on the constant light regimen have demonstrated the shift in sensitivity acrophase to 10 a.m.-4 p.m. and the prolongation of the daily period of increased sensitivity. With the animals' return to the natural regimen, a two-peak rhythm with the maximum sensitivity at 2 a.m. and 10 a.m.-2 p.m. and the minimum sensitivity at 22 p.m. and 6 a.m. was observed during the first 2 weeks-1 month. 2 months later the rhythm curve flattening was recorded, with the initial daily sensitivity rhythm to absolute hypercapnia recovering in 2 1/2 months.

[Chronotoxicity of cyclophosphane under different lighting conditions]. / Khronotoksichnost' tsiklofosfana pri razlichnom svetovom rezhime.

Study of the chronotoxicity of cyclophosphamide injected to mice at 18, 24, 6 and 12 o'clock has shown that animals kept under the conditions of natural changes of day and night showed the circadian rhythm of the drug toxicity with the maximal survival of the animals after injection at 24 and 6 o'clock and with the minimal survival after injection at 18 o'clock. In animals maintained under the conditions of artificial constant light the toxicity rhythm was perversed within the first hours after injection and improved on subsequent observation. Moreover the earlier death was marked in these animals.

[Comparative study of the level of mitotic activity and duration of mitosis over a 24 hour period in mouse tumors and normal tissue]. / Sravnitel'noe izuchenie urovnia mitoticheskoi aktivnosti i dlitel'nosti mitoza na protiazhenii sutok v opukholi i normal'noi tkani myshei

Circadian rhythm of cell division in the forestomack epithelium proved to be largely similar to that in the transplantable (continuous) carcinoma of the forestomack; the duration of mitosis in these tissues changed in the course of 24-hours. The mean 24-hour mitotic activity in the tumour was double that in the forestomack contrary to this, colchamine (colcemide) accumulated in the course of the 24-hours 121.1% mitoses in the forestomack and 83.8% mitoses in the carcinoma. A greater number of mitoses in the tumour with the usual count is attributed to the fact that the mean 24-hour duration of mitosis of the remen carcinoma was 2.7 greater than in the epithelium of the forestomack.