Rhythmometry gauges treatment of mesor-hypertension in the seventh and eight decades of life

Autorhythmometry of blood pressure by an individual over an age-span of 67 to 72 years showed a strong circadian rhythm superimposed upon significant circaseptan and circannual rhythms. Automatic BP monitoring with an Arteriosonde throughout 24-hour spans on 4 separate occasions, before and during treatment, also indicated a prominent circadian BP rhythm and a treatment-related reduction in circadian mesor. The concept of a blood pressure mesor reference for the antimesor-hypertensive treatment constitutes a valuable guideline in the control of "familial" mesor-hypertension.     

Chronobiology in 1975.

A spectrum of rhythms with several frequencies importantly characterizes not only the central nervous system but also the neuroendocrines and endocrines, other structures and organs, beyond the level of the cell to subcellular structures; it has a wide bearing since chronobiologic methods and facts relate to both basic research and its bearing on major problems of our day. Perhaps most important, computer analysis of data series allows study of temporal structure, progressive and rhythmic variations in life processes and in their responses to environment and drugs. By such methods coupled to modern data collection and/or self-measurement, chronobiology is particularly promising in the following areas, cited as illustrative rather than comprehensive examples: 1. Work hygiene: optimization of work schedules by adjustment of regular schedules and in particular of shift-work to the individuals' physical and mental rhythms. Experimentally, differences in manner of schedule change can account for the difference between the life span shortening and lengthening. 2. Population control: improved methods for detecting the neural as well as neurohormonal regulation of ovulatory cycles should aid efficient family planning by the recognition of a spectrum of rhythms and its synchronization with socio-ecologic factors acting, perhaps, via olfactory and/or other sensory modalities; 3. Nutrition: optimizing the utilization of ever scarcer food supplies and also the benefit from both oral and parenteral medications by meal timing; 4. Education: providing a do-it-yourself system for monitoring individual health in the context of secondary and adult education and as the basis for preventive health care; and, in another context, taking individual mental rhythms as well as morningness-eveningness into account in teaching and learning; 5. Health care: Any risk, e.g., from blood pressure rhythm alteration (perhaps preceding by years intermittent labile elevation) will be detected earlier and more efficiently by multiple measurements readily obtained by autorhythmometry. Results of such an endeavor provide at any one time indices that can be compared with an individualized rhythmometric reference standard as well as peer group rhythm parameters. The rhythm-determined average is more reliable than the single measurement. Other individualized characteristics of a rhythm, such as measures of extent of change or timing of change, may constitute an early warning signal and could be monitored by self-measured or preferably automatically-collected data. Timely and timed treatment can then be sought to prevent, in the case of blood pressure, elevation and consequent debilitating disease such as coronary infarction and stroke. 6. Therapy: One can strive toward the more specific correction of any pathogenic rhythm alteration when such can be recognized by modern methods of data collection and data analysis...     

Assessment of the risk of mesor-hypertension

A small number of selected (rather than randomly picked) women of three age groups was extensively sampled in two geographic locations. Data on twelve of the plasma hormones in addition to those on some systemic variables, including blood pressure (BP), determined around the clock and along the calendar were here analyzed further. The risk of developing certain diseases was assessed by epidemiologically designed questionnaires. The risk of cerebro-, reno-, cardiovascular disease was here approached by focus upon the risk of developing a high rhythm-adjusted mean (mesor) of BP. The risk of mesor-hypertension (RMH) for a selected group of young adult women was inversely correlated with the circannual amplitude (a measure of the extent of predictable since rhythmic change along the scale of a year) and the circannual mesor of plasma aldosterone. These indices are costly in several ways since it takes at least a year and quite a few samples to estimate them reliably. In the attempt to reduce sampling requirements to one or at most two plasma samples, a chronobiologic pattern discrimination analysis was undertaken on the original data from the subgroup of young adult women. Data were normalized by the sample standard deviation of each variable and processed according to proximity (so-called nearest neighbor) rules, for dimension reduction and classification. For each variable, each subject's samples were classified by reference to those of all others. The results objectively identify certain variables for further testing on larger, properly stratified and randomized cohorts followed preferably for a life-time and also illustrate the computer method of pattern discrimination used. Pattern discrimination not only singles out plasma aldosterone as the primary classifier for RMH, but shows further the circannual- and circadian-stage dependence of the classification. The clock-hour for optimal classification of RMH by aldosterone and by hormonal co-classifiers changes with the season. Furthermore, the relation between the circadian mesor of aldosterone concentration and RMH is an inverse one in summer, fall and winter, but a direct one in spring. A validated inverse relation to RMH of the circannual amplitude and mesor as well as any added differences in acrophase or waveform of aldosterone as a function of circannual stage all contribute to the change in sign of the relationship between aldosterone and RMH observed in spring. The latter change renders mandatory the specification as to clock-hour and season of any spot-check for risk assessment, whether it is based upon single or multiple samples.(ABSTRACT TRUNCATED AT 400 WORDS)     

Chronobiology in the clinical laboratory

'When to sample?' is a basic question in the clinical laboratory. After some considerations on the concept of biological time in laboratory medicine, the author discusses the implications of sampling time in laboratory tests, either they are performed for diagnosis and prognosis, monitoring therapy, prevention, assessment of risk or for legal reasons.     

Chronobiology in Asia

Sleep and Biological Rhythms -     

Chronobiology in hematology and immunology

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 mental retardation research: progress and prospects.

The premise of this review is that chronobiology, the science of biologic time structure and rhythms, is important in investigations concerning the etiology, mechanisms and effects of deficient mental adaptive development. Chronobiology is also shown to have potential importance in therapeutics and rehabilitation. Most of the information available now and supporting this wide-spread relevance of chronobiology relates to circadian rhythms, but physiological and behavioral rhythms having other cycle lengths also contribute. Recent findings in seven topic areas of chronobiology are reviewed with emphasis on facts and relationships actually or potentially important for consideration in mental retardation research. These are: 1) development of sleep and EEG patterns; 2) rhythmic susceptibility to seizures; 3) adrenocortical and dependent rhythms; 4) circadian rhythms in amino acids and biogenic amines; 5) rhythmic behaviors; 6) circadian rhythms in susceptibility and responses to drugs; and 7) circadian rhythms in human perception and performance.     

Chronobiology in mammalian health

Circadian rhythms are daily cycles of physiology and behavior that are driven by an endogenous oscillator with a period of approximately one day. In mammals, the hypothalamic suprachiasmatic nuclei are our principal circadian oscillators which influences peripheral tissue clocks via endocrine, autonomic and behavioral cues, and other brain regions and most peripheral tissues contain circadian clocks as well. The circadian molecular machinery comprises a group of circadian genes, namely Clock, Bmal1, Per1, Per2, Per3, Cry1 and Cry2. These circadian genes drive endogenous oscillations which promote rhythmically expression of downstream genes and thereby physiological and behavioral processes. Disruptions in circadian homeostasis have pronounced impact on physiological functioning, overall health and disease susceptibility. This review introduces the general profile of circadian gene expression and tissue-specific circadian regulation, highlights the connection between the circadian rhythms and physiological processes, and discusses the role of circadian rhythms in human disease.     

Chronobiology: anatomy in time

Chronobiology is that branch of science that objectively explores and quantifies mechanisms of biological time structure, including the important rhythmic manifestations of life. It is the study of biological rhythms. This paper introduces chronobiology and some of its vocabulary, principles, and techniques. A circadian rhythm is a regularly repetitive, quantitative physiological change with a period of about 24 hr (20-28), but the spectrum of rhythms includes those with periods less than 20 hr (ultradian) and longer than 28 hr (infradian). These rhythms are ubiquitous among the eukaryotes, innate and endogenous; their periods are precisely controlled by synchronizers in the environment. Rhythms can be manipulated by altering their synchronizers or by introducing more dominant ones. When organisms are removed from their environment and placed in constant conditions, rhythms revert to their natural frequencies and free-run. All of an organism's rhythms operate simultaneously, but their peaks and troughs do not necessarily occur at the same time. There are rhythms in susceptibility to drugs; a fixed dose may have a therapeutic effect at one point along the 24 hr time scale and a harmful one at another. Knowledge of these rhythms can be important when designing experimental or treatment protocols and interpreting results. Examples are provided to show that single-time-point sampling can lead to erroneous results, unless biological periodicity is taken into consideration.