Internal dissociation of the circadian markers of the cortisol rhythm in night workers

To determine whether the circadian system of night workers is adapted to a night-active schedule, we submitted 11 night workers and 11 day-active subjects to a 10-min blood sampling procedure during their usual sleep-wake cycle, permitting a precise determination of circadian and ultradian cortisol variations. In night works, the usual shift of 8 h in the sleep period was associated with a distortion of the normal 24-h cortisol rhythm. The acrophase exhibited a shift of approximately 6.5 h, whereas the quiescent period, abruptly interrupted by a large peak, underwent a shift of only 3 h and lasted for approximately 5 h, as in day-active subjects. Slow-wave sleep and sleep onset occurred during periods of low or decreasing cortisol secretory rates, whereas awakenings were associated with an increase in cortisol secretory rates. These results revealed that the circadian system of night workers only partially adapts to night work and that adaptation processes rely on an internal dissociation of the markers of the cortisol pattern, without disturbing the processes that couple cortisol release and specific sleep stages.

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Progesterone Might Be an Active Component of the Sleep-Wake Homeostatic Mechanism

Journal of the Endocrine Society ◽

10.1210/jendso/bvab048.1120 ◽

2021 ◽

Vol 5 (Supplement_1) ◽

pp. A550-A550

Author(s):

Georges Copinschi ◽

Anne H Caufriez

Keyword(s):

Sleep Disturbances ◽

Active Component ◽

Slow Wave Sleep ◽

Sleep Onset ◽

Sampling Procedure ◽

Blood Sampling ◽

Sleep Architecture ◽

Homeostatic Mechanism ◽

The Difference ◽

Spearman Test

Abstract Background: Using a randomized, double blind, placebo-controlled, crossover protocol, we have shown previously that progesterone may prevent sleep disturbances but has no action on undisturbed sleep. In that study, 8 healthy postmenopausal women took daily at 2300 h for 3 wk a capsule of either 300 mg of progesterone or placebo. Sleep was polygraphically recorded during the last two nights and, during the second night, blood samples were collected at 15-min intervals using an iv catheter,. During the first night, sleep was normal under placebo and progesterone had no effect. During the second night, blood sampling procedure was associated under placebo with marked sleep disturbances, which were considerably reduced under progesterone: at the group level, mean ± SEM duration of wake after sleep onset (WASO) dropped from 152 ± 37 min to 71 ± 19 min (P = 0.01), and slow-wave sleep (SWS) duration increased from 53 ± 6 min to 79 ± 10 min (P = 0.04). Objective: To submit individual data collected in that study to new analyses designed to further investigate possible mechanism(s) of progesterone actions on sleep architecture. Results: Among individual subjects, no relation could be evidenced between progesterone levels and sleep variables, or between individual progesterone-associated improvements and absolute values of corresponding sleep variables under placebo. By contrast, for WASO and SWS, significant positive correlations (Spearman test) were evidenced between individual responses to progesterone (i.e. the difference, during night 2, between value under progesterone and value under placebo) and corresponding individual alterations caused under placebo by the blood sampling procedure (i.e. the difference, under placebo, between value during night 1 and value during night 2): WASO: rs = 0.74, P = 0.037, n = 8; SWS: rs = 0.86, P = 0.014, n = 7. (Pearson test yielded similar results: WASO: r = 0.85, P = 0.008; SWS: r = 0.76, P = 0.047). Conclusions: Although they obviously need to be confirmed by larger studies performed in a variety of clinical conditions, the present findings suggest that progesterone action on sleep architecture is specifically tailored to restore individual normality rather than group normality. Since SWS is mainly regulated by the sleep-wake homeostatic mechanism relating sleep pressure to the duration of prior wakefulness, it is tempting to speculate that progesterone might be an active component of this mechanism.

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Progressive changes in airway resistance during sleep

Journal of Applied Physiology ◽

10.1152/jappl.1996.81.1.282 ◽

1996 ◽

Vol 81 (1) ◽

pp. 282-292 ◽

Cited By ~ 31

Author(s):

A. Kay ◽

J. Trinder ◽

Y. Kim

Keyword(s):

Airway Resistance ◽

Slow Wave Sleep ◽

Full Range ◽

Sleep Onset ◽

Upper Airway ◽

Young Male ◽

Nrem Sleep ◽

Sleep Stages ◽

Compensatory Mechanisms ◽

Sleep Period

Ventilation (V) decreases during sleep while upper airway resistance (UAR) increases. A number of studies have suggested that in normal healthy individuals the changes in the two variables are reciprocal. Other findings, however, suggest that the relationship between V and UAR may change as non-rapid-eye-movement (NREM) sleep progresses such that most of the change in V occurs early during the sleep period, whereas the most marked changes in UAR occur later during established NREM sleep. However, no study has examined the progressive development of changes in both V and UAR over the NREM sleep period. This study examined V and UAR over one NREM sleep period in two groups of healthy young male subjects: a "slow-wave sleep (SWS) group" (n = 8) in which the subjects obtained the full range of NREM sleep stages from wakefulness to stage 4 NREM sleep and a "no-SWS group" (n = 5) in which the subjects did not attain SWS but spent a prolonged period in stage 2 NREM sleep that was repeatedly interrupted by arousals. Results showed that the most marked changes in V occurred early during the sleep period in association with relatively small increases in UAR. Once NREM sleep became established, further attenuation of V was minimal despite marked and progressive increases in UAR. The progressive increase in UAR occurred in association with increasing delta (0.4- to 3.0-Hz) electroencephalographic activity and did not occur in the no-SWS group. We interpret these findings to indicate that factors in addition to UAR contribute to the reduction in V early in sleep onset, whereas later, during NREM sleep, compensatory mechanisms are activated to allow for maintenance of V in the context of larger increases in UAR.

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Sleep-electroencephalography and the secretion of cortisol and growth hormone in normal controls

Acta Endocrinologica ◽

10.1530/acta.0.1160036 ◽

1987 ◽

Vol 116 (1) ◽

pp. 36-42 ◽

Cited By ~ 61

Author(s):

A. Steiger ◽

T. Herth ◽

F. Holsboer

Keyword(s):

Growth Hormone ◽

Slow Wave ◽

Slow Wave Sleep ◽

Sleep Onset ◽

Cell Activity ◽

Cortisol Concentration ◽

Sleep Stages ◽

Sleep Structure ◽

Endocrine Activity ◽

Normal Controls

Abstract. Sleep-electroencephalography, and the nocturnal secretion of cortisol and GH were investigated simultaneously in a sample of 25 male normal controls (27.1 ± 1.3 years) in order further to examine interaction between sleep structure and concurrent endocrine activity. Slow wave sleep activity was increased during the first part of the night, whereas cortisol concentration was low and GH output reached maximal levels. The second half of the night was characterized by a relative preponderance of REM-sleep, low GH-concentration, and an increase in cortisol. However, no distinct reciprocal interaction between cortisol and GH concentration was noted. In all subjects, a pronounced GH surge between 22.00 and 02.00 h was recorded which occurred independently of the presence of slow wave sleep. Six out of the 25 subjects showed nocturnal GH increases even before sleep onset. These data indicate that somatotropic cell activity during night is less dependent upon the sleeping state or specific conventially defined sleep stages than originally reported.

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NOESY around the critical point Omega Tau c = 1.12. Precise determination of proton-proton distances and reorientation correlation times with two-field NOESY

Molecular Physics ◽

10.1080/002689700162621 ◽

2000 ◽

Vol 98 (4) ◽

pp. 201-210

Author(s):

Tao Zhang, Xi-An Mao, Matthias Baur, Ho

Keyword(s):

Critical Point ◽

Precise Determination ◽

Correlation Times ◽

Proton Proton

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Precise determination of 14 REEs in GSJ/AIST geochemical reference materials JCp-1 (coral) and JCt-1 (giant clam) using isotope dilution ICP-quadrupole mass spectrometry

GEOCHEMICAL JOURNAL ◽

10.2343/geochemj.2.0498 ◽

2018 ◽

Vol 52 (1) ◽

pp. 75-79 ◽

Cited By ~ 2

Author(s):

Tsuyoshi Tanaka ◽

Seung-Gu Lee ◽

Taehoon Kim ◽

Seunghee Han ◽

Hyo Min Lee ◽

...

Keyword(s):

Mass Spectrometry ◽

Reference Materials ◽

Isotope Dilution ◽

Precise Determination ◽

Giant Clam ◽

Quadrupole Mass ◽

Quadrupole Mass Spectrometry ◽

Geochemical Reference Materials

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Determination of Lead Content in Red Colored Lipsticks from Mandalay Market by Flame Atomic Absorption Spectrophotometer

Myanmar Health Sciences Research Journal ◽

10.34299/mhsrj.30.03.0045 ◽

2018 ◽

Vol 30 (3) ◽

pp. 167-173

Keyword(s):

Sampling Procedure ◽

The Body ◽

Lead Content ◽

Social Psychological ◽

Allowable Limit ◽

Flame Atomic Absorption ◽

Therapeutic Benefits ◽

Flame Atomic Absorption Spectrophotometer ◽

Exposure Levels

Red colored lipstick is the most widely used cosmetic product. Although lipstick gives a lot of social, psychological and therapeutic benefits, it may harm the consumers. Because some lipsticks contain a considerable amount of heavy metal especially lead. Lead is being used in lipstick mainly for the pigments required to obtain needed colors. Lead accumulates in the body over time and lead-containing lipstick applied several times a day, every day, combined with lead in water and other sources, could add up to significant exposure levels. Therefore, this study was aimed to determine lead content in red colored lipsticks from market. This study was laboratorybased, analytical study by using 25 lipstick samples. Red colored lipsticks were bought from Mandalay Market by random sampling procedure and they were completely coded to avoid the bias. Then, lead content in coded samples was determined by Flame AAS according to International Conference on Harmonization (ICH) guideline. Lead contents of 88% of the lipsticks samples were more than specified limit (20 ppm) of Food and Drug Administration, United States. All of them, lead content was highest in counterfeit lipsticks group. Among the tested lipstick samples, lipstick with lowest lead content was LE-RL 01 (15.74 ppm) and the lipstick with highest lead content was CF-RL 01(60.09 ppm). In conclusion, lead contents of red colored lipsticks (22 out of 25) from market samples were higher than allowable limit (20 ppm).

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PRECISE DETERMINATION OF THE IRRATIONAL PRE-FERRED INTERFACE ORIENTATION BY TEM

ACTA METALLURGICA SINICA ◽

10.3724/sp.j.1037.2010.00411 ◽

2010 ◽

Vol 46 (4) ◽

pp. 411-417 ◽

Cited By ~ 4

Author(s):

Yang MENG ◽

Lin GU ◽

Wenzheng ZHANG

Keyword(s):

Precise Determination ◽

Interface Orientation

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Nauwkeurige methode voor de aanwasbepaling van het grondvlak met behulp van de Pressler-boor

Silva Gandavensis ◽

10.21825/sg.v12i0.1009 ◽

1968 ◽

Vol 12 ◽

Author(s):

R. Goossens

Keyword(s):

Basal Area ◽

Precise Determination ◽

Maximum Diameter ◽

Precise Method ◽

Maximum Radius ◽

The Core ◽

Two Parameters

A precise method for the determination of the increment of the basal area using the PressIer bore. Refering to previous research showing that the basal area of the corsica pine could be characterized by an ellips, we present in this paper a precise method for the determination of the increment of the basal area. In this method we determine the direction of the maximum diameter, we measure this diameter and we take a core in one of the points of tangency of the caliper with the measured tree. The determination of the diameter perpendicular to the maximum diameter finishes the work wich is to be done in the forest. From the classical measurements effectuated on the core and from the measured diameters we can then determine the form (V) and the excentricity (e). Substituting these two parameters in the formula 2 or 2', we can also calculate the error of a radius measured on the core with respect to the representative radius, This error with them allow us to correct the measured value of the minimum or the maximum radius and we will be able to do a precise determination of the increment.

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