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L von Lindern

Publications and source records attributed to L von Lindern.

4 recordsLinked to original sources
PubMed1996

Decreasing period-length of the endogenous circadian rhythm of oxygen evolution in Acetabularia and its possible relation to aging.

Endogenous circadian rhythms observed under constant conditions normally show period length variations. However, a general trend is difficult to identify when cells or organisms are entrained with the usual 24-h-period light/dark cycles. Therefore, these variations in time have been considered as fluctuations. In order to gain more insight into this phenomenon, individual Acetabularia cells were exposed to light/dark cycles of 16 h (LD 8:8) and 33.6 h (LD 16.8:16.8), respectively, i.e., periods which lie distinctly outside the range of the normal circadian entrainment. Employing a high-resolution procedure for data analysis, decreasing period lengths could consistently be detected when cells were kept under constant conditions for several weeks. Possible causes of this decrease are discussed.

Acetabularia↗
PubMed1994

High-resolution measurement of circadian periodicities in Acetabularia.

Well-expressed endogenous circadian rhythms in Acetabularia acetabulum were spectrally analyzed and recorded in time-period distributions. The stability of the circadian periods under constant conditions and their changes could be monitored continually in step sizes close to the circadian period length. The resolution of period estimates of the circadian component was increased by a factor of approximately 4-10 by adapting analyzed interval lengths to full period sizes of the corresponding main component. Methodological aspects of the applied algorithms are discussed by means of examples that measure the temperature dependency of the circadian period.

Acetabularia↗
PubMed1985

Circadian rhythms in endogenous depression.

A comprehensive study of circadian rhythms was carried out in 16 drug-free patients with endogenous depression, 10 of whom were reinvestigated after clinical remission, and 10 healthy controls. No free-running periods were observed in body temperature, urinary excretion of potassium and free cortisol, or any other variable. Moreover, there was little, if any, indication of phase-advance. The circadian variation of several variables was reduced during depression, e.g., motor activity, body temperature, and (less markedly) urinary potassium, but not cortisol. The circadian worsening of mood tended to occur around the time of awakening during depression, i.e., several hours later than after remission or in normal controls. In patients with circadian variation of self-rated mood, the acrophase of this variable correlated significantly with that of urinary free cortisol. This indicates an entrainment of the disease process to the circadian rhythm of cortisol secretion, probably via circadian variations of neurotransmitters in the hypothalamus. The other circadian phenomena observed in depression can adequately be explained by masking effects (negative or positive) of psychopathological symptoms (e.g., early morning awakening) on overt circadian rhythms.

Adult↗