Showing papers by "Erhard Haus published in 2006"

Biological clocks and shift work: circadian dysregulation and potential long-term effects.

Abstract: Long-term epidemiologic studies on large numbers of night and rotating shift workers have suggested an increase in the incidence of breast and colon cancer in these populations These studies suffer from poor definition and quantification of the work schedules of the exposed subjects Against this background, the pathophysiology of phase shift and phase adaptation is reviewed A phase shift as experienced in night and rotating shift work involves desynchronization at the molecular level in the circadian oscillators in the central nervous tissue and in most peripheral tissues of the body There is a change in the coordination between oscillators with transient loss of control by the master-oscillator (the Suprachiasmatic Nucleus, SCN) in the hypothalamus The implications of the pathophysiology of phase shift are discussed for long-term health effects and for the design of ergonomic work schedules minimizing the adverse health effects upon the worker

Periodicity in response and susceptibility to environmental stimuli.

Abstract: A frequency structure of physiologic functions is an expression of the temporal organizations of metabolism in man and animals. The frequencies involved range from the fraction of a second, as in single nerve cells, to circadian, monthly and seasonal variations. Many of these rhythms may play a role in the organism’s response to environmental stimuli. For the purpose of this discussion we shall limit ourselves to the rather drastic changes in response to environmental agents which were found to be a temporal function of the phase relations of circadian rhythms. The field of circadian rhythms in general and related work has been extensively reviewed in a number of recent publication^.^-'^ By use of appropriate standardization and experimental technique?. l6

Variance spectra of corticosteroid in adrenal venous effluent of anesthetized dogs

Abstract: The question as to whether corticosteroid concentration in blood leaving the adrenal gland of the dog is a rhythmic function will be discussed herein. Data from anesthetized animals bearing adrenal venous cannulas will be analyzed for this purpose by pooled variance The indications for this type of analysis and qualifications thereof will be provided. A series of earlier investigations of corticosteroid output in the dog, particularly those by Hume and Egdahl, were aimed at the study of factors controlling adrenal secretion6*O and have already provided reference to changes in hormone level as a function of time: “Of particular interest was the observation that when repeated measurements of adrenal secretion in the resting state were made throughout the day in a given animal a succession of very low values might be found, and then, all a t once, an elevated value, flanked on both sides by values of very low range. It was as though a little “puff” of ACTH were being secreted a t periodic intervals ta maintain adrenal reactivity, and to produce a daily secretion of adrenal steroid adequate to maintain the minimal requirements of the resting state.”6 But apparently no information is available on the average length of the “periodic intervals” separating the puffs or on their variability.

CHAPTER 213 – Peptide Chronomics

Abstract: Chronomics, the mapping of broad time structures (chronomes), provides the indispensable control whether studies aim at examining the effect of a given intervention such as dietary restriction, at optimizing the timing of administration of treatment, or at assessing an elevated risk of developing a disease such as cancer. An increase in circadian amplitude exceeding any effect on the mean is likely to yield controversial results from single spot checks. An analog of the adrenocorticotropic hormone (ACTH 1–17), administered in the evening may help patients with rheumatoid arthritis, but may be ineffective when given around awakening. A daytime single sample of prolactin may not be discriminatory in assessing breast cancer risk when large differences are found during the rest span. The merits of assessing peptide chronomics are perhaps best illustrated by the facts that a peptide drug may have a major effect at one circadian stage but not at another, that a major effect on a polypeptide may be exerted again at one circadian stage but not at another, and that, by the design and the software of chronomics, relatively small numbers of patients are needed to validate such effects by inferential statistics.