Circadian variations in clock gene expression of human bone marrow CD34+ cells

Time-dependent variations in clock gene expression have recently been observed in mouse hematopoietic cells, but the activity of these genes in human bone marrow (BM) has so far not been investigated. Since such data can be of considerable clinical interest for monitoring the dynamics in stem/progenitor cells, the authors have studied mRNA expression of the clock genes hPer1 , hPer2, hCry1, hCry2, hBmal1, hRev-erb alpha, and hClock in human hematopoietic CD34-positive (CD34( +)) cells. CD34(+) cells were isolated from the BM samples obtained from 10 healthy men at 6 times over 24 h. In addition, clock gene mRNA expression was analyzed in the whole BM in 3 subjects. Rhythms in serum cortisol, growth hormone, testosterone, and leukocyte counts documented that subjects exhibited standardized circadian patterns. All 7 clock genes were expressed both in CD34(+) cells and the whole BM, with some differences in magnitude between the 2 cell populations. A clear circadian rhythm was shown for hPer1, hPer2, and hCry2 expression in CD34(+) cells and for hPer1 in the whole BM, with maxima from early morning to midday. Similar to mouse hematopoietic cells, h Bmal1 was not oscillating rhythmically. The study demonstrates that clock gene expression in human BM stem/progenitor cells may be developmentally regulated, with strong or weaker circadian profiles as compared to those reported in other mature tissues.     

Circadian variations in the sweating mechanism.

Sweat rates and body temperatures of human subjects were measured at 0200, 1000, and 1800 h during a heat exposure of 90 min. The latent period of sweating was not significantly altered in the evening but significantly shortened during the night. Mean body temperature corresponding to the onset of sweating was nearer to the basal body temperature during the night, while during the day the difference between these two temperatures became larger. This phenomenon seems related to the circadian cycle of vasomotor adjustment, since during the night body conductance was higher than during the day and corresponded to a state of a vasodilatation similar to that observed at the onset of sweating. During the day, this situation was reversed. During steady state, the following changes were observed: sweating rate, night less than morning less than evening; skin temperatures, night less than morning less than evening; and rectal temperature increase, morning less than evening less than night. It is hypothesized that these changes are due to either different metabolic rates or an imbalance between heat gains and losses which preserve the circadian rhythm of the body temperature, even under thermal loads.     

Circadian variations of haemolymph lipoprotein of Palaemon serratus

The electrophoretic behaviour of haemolymph lipoprotein was determined throughout a 24 h light-dark cycle. All of the 14 lipoprotein bands did not always appear at the same time, and their level did not remain constant, showing mainly tri- and tetracircadian variations. Values are not the same in males and females. Despite the fact that the lipoprotein variation was not closely synchronized with circadian periodicity, some lipoproteins were responsible for light-dark transition.     

Circadian variations in serum thyroid hormones inMacaca fascicularis

Serum triiodothyronine (T₃) and thyroxine (T₄) concentrations inMacaca fascicularis were determined at 4-hr interval for 24 hr using commercial radioimmunoassay kits. It was found that the highest concentrations of T₃ and T₄ in the animals were in the serum sample taken at 10:00. The lowest values of T₃ and T₄ were found in the blood sampled at 02:00 and 22:00, respectively.     

Circadian variations in the oxygen-consumption of anterior segments of earthworms

Summary The oxygen-consumption of anterior segments (prostomium plus the first six segments) of earthworms, Lumbricus terrestris L., was measured around midday and in the evening on 25 days of late winter and early spring. The preparations were cut from animals which had lived in complete darkness for at least several days prior to their being studied. Data for 1) anterior pieces with intact suprapharyngeal ganglia (brain), for 2) pieces from which those ganglia had been removed about an hour before the segments were placed in the respirometers, for 3) pieces in which the circumpharyngeal connectives had been severed approximately an hour before measurements were made and for 4) pieces from which the ganglia had been removed 42 hours before recording, are presented in Tables 1 and 2.The average oxygen-consumption of preparations of the first three groups was 22 to 25% greater (p<0.05) in the evening than at noon, i. e., the circadian variation was found whether or not the central nervous system had been manipulated shortly before respiratory rates were determined. However, for the preparations of type 4), the differences between midday and evening rates were less, averaged only 16%, and were not statistically significant. Those findings may indicate that the longterm maintenance of the circadian variation in oxygen-consumption does depend upon nervous mediation or synchronization.     

Circadian variations in pyrimidine nucleotide synthesis in rat liver

The biosynthesis of pyrimidine components in rat liver varies with the time of the day. The concentrations of both the cytidine and the uridine components of the acid-soluble extract are lowest in the morning hours and highest around midnight. The utilization of [2-¹⁴C]orotic acid for the synthesis of the pyrimidine components of the acid-soluble extract, RNA, and DNA has a similar character. Analogous changes also are seen in the uptake of [U-¹⁴C]cytidine and its utilization for the synthesis of RNA cytosine.     

Circadian variations in self-monitoring,a component of executive functions

The objective of this study was to identify circadian rhythms in self-monitoring, a component of executive functions. Participants were 10 undergraduate students, age: 18.5 ± 2.68 years, two male and eight female. They were recorded on a 30-h constant routine protocol; rectal temperature was recorded every minute and performance on a tracking task was assessed every 100 min. Self-monitoring indicators were adjustments of responses to random changes of speed and trajectory of a circle moving on the computer screen. Participants showed better accuracy during the afternoon, with decreases in the morning (06:20 and 08:00 h). These variations showed a phase delay of 2:29 ± 2:19 h with respect to the circadian rhythm of body temperature. In conclusion, there are circadian variations in self-monitoring. The decline in this component of executive functions could cause serious accidents among people working or studying during a morning shift, as well as commuting to and from work or school.     

No narcosis for bone marrow harvest in autologous bone marrow transplantation

A prospective study with mild general analgesia and sedation together with local anesthesia during bone marrow harvest was performed. Thirty-one patients underwent 33 bone marrow collections. Pretreatment consisted of 100 mg meperidine i.m. and 20 mg diazepam i.m. 1 h before start of procedure. Eight patients got additional meperidine and diazepam during the procedure, all patients got lidocaine 1% locally. A mean volume of 1.321 was obtained with 42.5 punctures. Twenty-two patients had no complications, 4 vomited, 4 had easily correctable hypotension of short duration, one got oxygen for cyanosis of short duration. Acceptance was good in 23 patients, in 6 reasonably well, in two bad. Only one patient experienced pain problems, due to suction. Anxiety was no major problem due to good information before the procedure and mild sedation. This form of anesthesia for bone marrow collection is a safe procedure, it is generally well accepted by the patient and it can be performed on an out-patient basis.