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Biomedical subjects

F Halberg

Publications and source records attributed to F Halberg.

At least 145 records · Page 8Linked to original sources
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↗
PubMed1989

Control of a murine plasmacytoma with doxorubicin-cisplatin: dependence on circadian stage of treatment.

In anticipation of the development of clinical chronotherapy and in order to pick clinical test times for doxorubicin and cisplatin trials, two large studies were performed on rats bearing a transplanted plasmacytoma. The circadian timing of each of two anticancer drugs given at precisely equal dose intensities was expected to improve therapeutic benefit over conventionally given (time-unqualified) treatment. In each chronotherapeutic study, maximal benefit and minimal toxic effects were found when cisplatin was administered in the middle to latter part of the daily activity (dark) span, while doxorubicin was administered near the end of the daily resting (light) span for these nocturnally active rodents living on a 12-hour-12-hour or 8-hour-16-hour light-dark schedule. This was true whether doxorubicin or cisplatin was given first and whether there was a lag of only a few hours or a few days between the administration of these two agents.

Animals↗
PubMed1989

Circaseptan (about 7-day) modulation of circadian rhythm in corneal mitoses of Holtzman rats.

An infradian modulation with a 168 h or circaseptan period characterizes epithelial corneal mitoses in adult female and male Holtzman rats, standardized at 24 +/- 1 degree C and approximately 50% relative humidity on six different sequences of light (L) alternating every 12 h with darkness (D). To approximate sampling over a 24 h LD span by convenient sampling within a single hour, the LD 12:12 regimen was staggered by 4 h in the six environments. Bedding was changed 3 days before each day of killing. During each of eight or 12 consecutive days, male and female rats, respectively, were killed and the eyeballs were removed. Mitotic indices in the cornea were determined separately for each eye and the data were analyzed by linear and nonlinear least-squares rhythmometry. For a prominent circadian component of mitotic activity, the 95% confidence interval (CI) of the period extends from 23.6 to 24.3 h for the data from males and from 23.7 to 24.2 h for those from female rats. The circadian amplitude is larger in males as compared to females. The peaks in the 24 h cosine functions best approximating the data, the circadian acrophases, are at -64 degrees or -48 degrees, i.e., 4 h 16 min or 3 h 12 min from lights-on in male and female rats, respectively. In the data from the two genders, the 24 h synchronized circadian acrophases are thus only 16 degrees, i.e., 1 h and 4 min apart. A test for an anticipated circaseptan (7-day) period shows that this particular infradian periodicity is superimposed upon the circadian one in data from both genders.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Some aspects of the chronobiology of nutrition: more work is needed on "when to eat".

Chronobiology involves the objective resolution with modern hardware and software of biologic time structure, now known to characterize most, if not all, body functions; it is also the science of timely intervention, a challenge to nutritionists. At all ages, yet the sooner the better, starting preferably in the womb but at least immediately after birth, the application of the principles of chronobiology requires the study of nutrition. In many cases, e.g., in the case of an increased risk of developing high blood pressure later in life, dietary preventive interventions should eventually precede drug treatment. That such intervention should take place at the earliest individualized recognition of risk seems reasonable and is an aim of chronobiologic research. In any event, a mathematical rhythm spectrum becomes evident in any variable measured with sufficient density over an appropriately long span; it constitutes the fabric of all life. In the science and practice of nutrition today, "cherchez le contrôle" (i.e., the provision of a control) requires the assessment of a multifrequency rhythmic structure.

Animals↗
PubMed1989

Infradian modulation of liver nucleic acid and lipid content of adult female Lewis/S rats.

Infradian modulation with periods of 168 h and 120 h characterizes the RNA, DNA and lipid content of the liver in adult female Lewis/S rats. Multilinear analysis shows that the fit of an infradian cosine curve with these periods is statistically significant below the 5% level (P = 0.011; P = 0.007 and P = 0.013) and that they account for 19.0, 22.7 and 20.1% of the overall variability, respectively.

Activity Cycles↗