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Biomedical subjects

F Halberg

Publications and source records attributed to F Halberg.

At least 55 records · Page 3Linked to original sources
PubMed1990

Further extensions of the cosinor approach to problems of the pharmaceutical industry.

The resolution of a more complex time structure than that described by the useful first approximation of a single cosinor is suggested herein. The cosinor serves the purpose of parsimony in the case of sparse and short time series, yet it can be usefully extended by assessing the variations in rhythm characteristics for treatment timing in the clinic rather than only for research.

Animals↗
PubMed1990

Endpoints of chronobiologic cardiovascular monitoring during pregnancy for planning exercise and assessing effects.

The chronobiologic question is raised whether exercise may be indicated for the pregnant woman as a general prophylactic measure and, if so, whether it should be timed according to rhythms and stage of pregnancy. This question, recently considered by others without chronobiologic focus, is here reviewed against the background of results from ongoing chronobiologic studies of blood pressure (BP) and heart rate (HR) in pregnancy. During pregnancy, the MESORs and circadian amplitudes of systolic (S), mean arterial (MA) and diastolic (D) BP are correlated with a questionnaire-assessed cardiovascular risk score. Such results were found under noisy ordinary conditions of life without accounting for effects of activity. They are group results, and as such require further work before they can contribute to identifying individuals at high risk in particular need of intervention, such as exercise. The dependence of exercise effects upon circadian rhythms should also prompt the use of rhythmometry at all ages for timing exercise, for gauging its effects and eventually for the optimization of fitness training for the population as well as for peak performance.

Blood Pressure↗
PubMed1990

Chronoendocrine assessment of the risk of developing depressive disorders.

Chronoepidemiology studies alterations of biologic rhythms with several frequencies as harbingers and possibly determinants of the risk of developing certain diseases. Along these lines, a method for pattern discrimination, the so-called "monotest", involving the leave-one-out technique for the estimation of the PM, is here used in the search for classifiers of personality. By this method, chronoendocrine relations of a DPP are explored in 12 plasma hormones sampled around the clock in 4 seasons on a small number of clinically and psychologically healthy women, 29-36 years of age. Subjects were separated in two groups by scores for DPP of the Mini-Mult, an abbreviated version of the Minnesota Multiphasic Personality Inventory. Discriminant analysis singles out plasma aldosterone as the primary classifier for DPP in winter. In spring, the best classifiers include 17-OH progesterone and insulin, whereas in the summer the circadian amplitude of 17-OH progesterone classifies best. Finally, the identified classifiers in the fall are DHEA-S, estradiol and estrone. In clinical health, hormones are thus sensitive in ordering people who, according to questionnaires, are at different risk of developing emotional disorders. Results also illustrate the need to consider the intermodulation of circadian and circannual rhythms, whenever endocrine variables are being determined in human plasma.

Adult↗
PubMed1990

Longitudinal chronobiologic blood pressure monitoring for assessing the need and timing of antihypertensive treatment.

To examine the need for antihypertensive therapy and its timing, a 46 year-old woman with a 10-year history of "mild to moderate hypertension," treated for that span with 50 mg of hydrochlorothiazide per day, usually taken before retiring, carried out a study in a series of stages. Throughout the first 8 stages, she monitored her blood pressure and heart rate at 15-minute intervals around the clock for 70 consecutive days. In the first two stages, her medication was continued for a total of 10 days, of which the last 7 days constituted a double-blind study start. For the next 25 days, she was placed on a placebo once in the evening. For the ensuing week, she received three tablets per day (in the morning, noon and evening), with all three being placebo. Thereafter, for consecutive 7-day spans, she was placed on treatment, only in the morning, only at noon or only in the evening, with placebo at other times. The desirability of one vs. another treatment was assessed by a comparison of slopes fitted to the daily MESORs; on that basis, the morning or noon treatment appeared to be possibly superior to the evening treatment. Eventually the patient was taken off medication; 5 months later her sphygmochrons, based on two-to-six day monitoring, were acceptable by current standards. The slope of MESORs may be a useful endpoint to assess the need for medication, to optimize its timing or to establish the likelihood that medication is not needed. This approach should, however, be based on several (rather than a single) double-blind alternation of drug and placebo treatments for spans that are the longer the smaller the extent of apparent blood pressure elevation. Thus, in the case of apparent mild MESOR-hypertension, the blood pressure MESOR changes following the change in medication should be assessed during spans longer than one week. In the particular case studied, it seems possible that the patient had taken medication for 10 years, perhaps without justification. In cases of very mild blood pressure elevation, it seems desirable, by self-measurement or preferably automatic measurement, to take the patient off medication for spans measured in weeks or preferably months rather than days, in order to rule in or rule out the need for treatment, on the basis of repeated blood pressure profiles, to be compared eventually with reference standards from peers at low familial and personal risk of developing high blood pressure.

Antihypertensive Agents↗