The brain decade in debate: IV. Chronobiology.

The present article is the adapted version of an electronic symposium organized by the Brazilian Society of Neuroscience and Behavior (SBNeC) which took place on June 14, 2000. The text is divided into three sections: I. The main issues, II. Chronodrugs, and III. Methods. The first section is dedicated to the perspectives of chronobiology for the next decade, with opinions about the trends of future research being emitted and discussed. The second section deals mostly with drugs acting or potentially acting on the organism's timing systems. In the third section there are considerations about relevant methodological issues concerning data analysis.

The brain decade in debate: IV. Chronobiology

The present article is the adapted version of an electronic symposium organized by the Brazilian Society of Neuroscience and Behavior (SBNeC) which took place on June 14, 2000. The text is divided into three sections: I. The main issues, II. Chronodrugs, and III. Methods. The first section is dedicated to the perspectives of chronobiology for the next decade, with opinions about the trends of future research being emitted and discussed. The second section deals mostly with drugs acting or potentially acting on the organism's timing systems. In the third section there are considerations about relevant methodological issues concerning data analysis

[Chronobiological profile of arterial blood pressure and heart rate in a family group determined by automatic monitoring]. / El perfil cronobiológico de tensión arterial y de frecuencia cardiaca en un grupo familiar, determinado mediante monitorizacion automática.

Over a week, blood pressure (systolic, mean and diastolic) and heart rate were determined in a family, by means of automatic, uninterrupted monitoring. The chronobiological profile for each family member was prepared in time series of various periodicities. An ample circadian component and a lesser circaseptan component were apparent. Clear phase differences were identified among the four cardiovascular variables studied. The chronobiological profile of the children was closer to that of the father than to that of the mother.

[Chronobiology in medicine and surgery]. / Cronobiología en medicina y cirugía.

Chronobiology studies predictable variations, rhythms and trends in all forms of life. Each physiologic variable or system in an organism has a time structure which is genetically anchored and capable of being expressed in the absence of external cycles. However, it is normally adjusted by geophysical changes. Chronobiology quantifies rhythms by providing measures of amplitude and timing (phase and period), and a mean more precise than the arithmetic mean. The correct measurement of biological rhythms has led to considerable advances in the understanding of their underlying mechanisms of generation and expression. The use of information on rhythms is opening new opportunities in the prevention, diagnosis and treatment of disease. Chronobiology is also effective in the improvement of the quality of life by teaching self-help to the healthy individual.

Ultradian-infradian variation of cardiac creatine phosphokinase (CPK) activity in male Holtzman rats.

Reference standards were sought for use in the search of any indications of myocardial damage by an alteration of the time structure, or chronome, of creatine phosphokinase (CPK) "MB" isoenzyme activity in the heart of the male Holtzman rat. 144 rats were kept on 6 lighting regimens staggered by 4 hours, 24 rats per chamber. On 8 consecutive days, hearts from 3 animals from each chamber were harvested and weighed. The left ventricle was dissected, homogenized in a buffer solution at 4 degrees C and stored frozen at -20 degrees C until analysis. A supernatant aliquot of each sample was analyzed by a discontinuous gradient elution from DEAE-Shephadex A-50 columns. The CPK isoenzymes were quantified by the Rosalki method. Results of the CPK assay from each time point were analyzed by linear and nonlinear least-squares rhythmometry. Among other components, a 168h or circaseptan rhythm characterized CPK activity in the heart of Holtzman rats. This component and other ultradian and circadian aspects of the time structure of rhythms and trends, the chronome of a given variable, may serve, by any eventual alteration of their dynamic characteristics, as gauges of potential cardiac damage prior to the occurrence of an increase in the overall mean of the enzymatic activity.

Experimental models for the study of chronoimmunomodulation (rhythms of the springtail Folsomia candida, Collembola: Isotomidae).

A third-generation cephalosporine, cefodizime, was tested in two experiments on the springtail, Folsomia candida, used as a model of infradian rhythmicity. Any effect on ecdysis (molt), oviposition and oviproduction was sought for 6, 20 or 60 ng of cefodizime administered with brewer's yeast every other day, as compared to controls given only the yeast. Results indicate that a 20-ng dose of cefodizime on alternate days may shorten an infradian period (of molt) in the springtail.