http://ieeexplore.ieee.org/iel5/5007879/5007912/05007924.pdf

Biological Rhythms

https://www.cell.com/trends/plant-science/pdf/S1360-1385(09)00301-X.pdf

Molecular mechanisms of polyploidy and hybrid vigor

In all of its components, the immune system shows regularly recurring, rhythmic variations in numerous frequencies; the circadian (about 24 h) rhythms are the best explored. The circadian variations in immunocompetent cells circulating in the peripheral blood are of a magnitude to require attention in medical diagnostics. Both the humoral arm and the delayed (cellular) arm of the immune system function in a rhythmic manner. The response of the immune system to introduction of an antigen and to challenge of the sensitized organism varies in extent in the circadian frequency range and also in lower frequencies, for example, of about a week (circaseptan) or seasonally (circannual). The medical application of the biologic rhythms of the immune system extends to diagnostic measures, as well as treatment.

Biologic Rhythms in the Immune System

The hematopoietic and the immune systems in all their components are characterized by a multifrequency time structure with prominent rhythms in cell proliferation and cell function in the circadian, infradian, and rhythms in cell proliferation and cell function in the circadian, infradian, and circannual frequency ranges. The circulating formed elements in the peripheral blood show highly reproducible circadian rhythms. The timing and the extent of these rhythms were established in a clinically healthy human population and are shown as chronograms, cosinor summaries and, for some high-amplitude rhythms, as time-qualified reference ranges (chronodesms). Not only the number but also the reactivity of circulating blood cells varies predictably as a function of time as shown for the circadian rhythm in responsiveness of human and murine lymphocytes in vitro to lectin mitogens (phytohemagglutinin and pokeweed mitogen). Some circadian rhythms of hematologic functions appear to be innate and are presumably genetically determined but are modulated and adjusted in their timing by environmental factors, so-called synchronizers. Phase alterations in the circadian rhythms of hematologic parameters of human subjects and of mice by manipulation of the activity-rest or light-dark schedule and/or of the time of food uptake are presented. Characteristically these functions do not change their timing immediately after a shift in synchronizer phase but adapt over several and in some instances over many transient cycles. The circadian rhythm of cell proliferation in the mammalian bone marrow and lymphoid system as shown in mice in vivo and in vitro may lend itself to timed treatment with cell-cycle-specific and nonspecific agents in an attempt to maximize the desired and to minimize the undesired treatment effects upon the marrow. Differences in response, and susceptibility of cells and tissues at different stages of their circadian and circaseptan (about 7-day) rhythms and presumably of cyclic variations in other frequencies are expected to lead to the development of a chronopharmacology of the hematopoietic and immune system. Infradian rhythms of several frequencies have been described for numerous hematologic and immune functions. Some of these, i.e., in the circaseptan frequency range, seem to be of importance for humoral and for cell mediated immune functions including allograft rejection. Infradian rhythms with periods of 19 to 22 days seem to occur in some hematologic functions and are very prominent in cyclic neutropenia and (with shorter periods) in its animal model, the grey collie syndrome.(ABSTRACT TRUNCATED AT 400 WORDS)

Chronobiology in hematology and immunology

Fasting of mice is a common procedure performed in association with many different types of experiments mainly in order to reduce variability in investigatory parameters or to facilitate surgical procedures. However, the effects of fasting not directly related to the investigatory parameters are often ignored. The aim of this review is to present and summarize knowledge about the effects of fasting of mice to facilitate optimization of the fasting procedure for any given study and thereby maximize the scientific outcome and minimize the discomfort for the mice and hence ensure high animal welfare. The results are presented from a number of experimental studies, providing evidence for fasting-induced changes in hormone balance, body weight, metabolism, hepatic enzymes, cardiovascular parameters, body temperature and toxicological responses. A description of relevant normal behaviour and standard physiological parameters is given, concluding that mice are primarily nocturnal and consume two-thirds of their total food intake during the night. It is argued that overnight fasting of mice is not comparable with overnight fasting of humans because the mouse has a nocturnal circadian rhythm and a higher metabolic rate. It is suggested that because many physiological parameters are regulated by circadian rhythms, fasting initiated at different points in the circadian rhythm has different impacts and produces different results.

https://journals.sagepub.com/doi/pdf/10.1177/0023677213501659

Fasting of mice: a review

Summary and conclusionsThe following variables were studied in the mouse under conditions standardized for evaluation of 24-hour periodicity: glucose and “corticosterone” in blood; mitoses in pinna...

24-Hour rhythms at several levels of integration in mice on different lighting regimens.

Under conditions standardized for analysis of 24-hour periodicity, with light from 06:00 to 18:00 alternating with 12 hours of darkness, corticostcrone in mouse serum undergoes reproducible 24-hour changes, with peak blood levels at about 16:00. Significant differences in phase characterize the 24-hour rhythms in serum corticosterone and in mitoses of cortical adrenal parenchyma; under the same lighting conditions, the peak of the latter occurs at about midnight. The corticosterone rhythm leads in phase the rhythm in gross motor activity and lags behind the eosinophil rhythm, in the absence of intentional stimulation other than daily routine. As compared to the significant change in blood corticosterone level along a 24-hour scale, the immediate effect of audiogenic stimulation upon serum corticosterone is slight. It consists of a small rise following stimulation at the time of the daily “corticosterone low” and is negligibleafter stimulation at the time of “corticosterone high.”The daily rhythm in blood ...

Phase relations of 24-hour periodicities in blood corticosterone, mitoses in cortical adrenal parenchyma, and total body activity.

Summary1. Linear glutamyl peptides of number average molecular weight up to 122,-000 are rapidly excreted in the urine of humans and removed from the blood stream in 6 hours or less. In the dog disappearance of these peptides from the plasma is much slower. In this animal the plasma half life time for peptides of number average molecular weight of 57,000 to 122,000 appears to be between 9.5 to 11 hours. 2. Doses of up to 19 g of these peptides had no significant effect on temperature, pulse, respiration, blood pressure, cellular elements or clotting functions of the blood in humans.

Comparison of Excretion Rates of Linear Glutamyl Peptides in Humans and Dogs

ConclusionsTwo compounds, 5,6-dimethylbenzimidazole and 1,2-dimethyl 4,5-diaminobenzene, which have been previously implicated in vit. B12 metabolism, were found to inhibit the growth of Mycobacterium tuberculosis, strain H37Rv, in Dubos Medium.

Robert H. Silber

Papers

24-Hour rhythms at several levels of integration in mice on different lighting regimens.

Phase relations of 24-hour periodicities in blood corticosterone, mitoses in cortical adrenal parenchyma, and total body activity.

Comparison of Excretion Rates of Linear Glutamyl Peptides in Humans and Dogs

Inhibitory Effect of 5,6-Dimethylbenzimidazole and of 1,2-Dimethyl, 4,5-Diaminobenzene on Growth of Mycobacterium tuberculosis.