Circadian rhythms and clinical chronobiology

Characteristics of infradian and circadian rhythms in the persistent vegetative state

This retrospective study investigated the circadian and infradian characteristics of blood pressure and heart rate in 26 patients with traumatic head injury in a persistent vegetative state (PVS). Systolic and diastolic blood pressures and heart rate were measured every hour for the first 240 h (10 days) following hospital admission. These data were analysed for the presence of circadian and infradian rhythms using the least-squares fit of the cosine function with the single cosinor method. Infradian rhythms were defined as biological rhythms with a period of approximately 7 days (circaseptan rhythms). All the patients studied had circadian and circaseptan rhythms of systolic and diastolic blood pressures and heart rate. The amplitudes of all the circaseptan rhythms were significantly greater than those of the corresponding circadian rhythms. It was concluded that there was an altered association between circadian and infradian blood pressure and heart rate rhythms in patients in a PVS. Circadian and infradian rhythms were present, but the infradian rhythm had a greater amplitude than the circadian rhythm.

Circadian effects on outcome following surgery for intracerebral hemorrhage in humans?

Previous studies indicated that recovery of brain injury involves in circadian system and circadian system also modulates cardiovascular function. The present study was focused on the circadian characteristic of blood pressure (BP) and heart rate (HR) of patients with hypertensive intracerebral hemorrhage (HICH) after neurosurgical operation at the first 24-hour and its relationship to prognosis of HICH. This retrospective study was based on the analysis of circadian rhythm of postoperative patients with HICH who received no anti-hypertensive treatment before operation and during the first 24-hour after operation. Series data of BP and HR after operation were analyzed with cosinor method to determine whether circadian rhythms were present or absent. The patients were divided into two groups, including presence of circadian rhythm group and absence of circadian rhythm group. The basic clinical characteristics of two groups were analyzed with Student's t-test. The percentage of good prognosis in two groups was analyzed with Pearson's Chi-squared test. Statistical results indicated that the percentage of good prognosis was significantly different between the presence and absence group. More cases of good prognosis in presence group of Systolic Blood Pressure (SBP) was discovered than in absence group (p=0.032). The results of Diastolic Blood Pressure (DBP) and HR were similar as SBP was observed in presence group for DBP (p=0.002) and for HR (p=0.001), respectively. We conclude that the presence or absence of circadian rhythm after operation would be an early predictor of the postoperative prognosis from hypertensive intracerebral hemorrhage.

A connection between MAPK pathways and circadian clocks

Circadian clocks and mitogen-activated protein kinase (MAPK) signaling pathways are fundamental features of eukaryotic cells. Both pathways provide mechanisms for cells to respond to environmental stimuli, and links between them are known. We recently reported that the circadian clock in Neurospora crassa regulates daily rhythms in accumulation of phosphorylated, and thus active, OS-2 MAPK, a relative of mammalian p38 MAPK, when cells are grown in constant conditions. In the absence of acute stress, rhythmically activated MAPK then signals to downstream effector molecules to regulate rhythmic expression of target genes of the pathway. Clock regulation of MAPK signaling pathways provides a mechanism to coordinately control major groups of genes such that they peak at the appropriate times of day to provide a growth and survival advantage to the organism by anticipating stresses. MAPK pathways are well known for their role in cell proliferation and tumor suppression. New evidence reveals that some mammalian clock components also function as tumor suppressors and rhythms in phospho-MAPK have been observed in higher eukaryotes. Thus, the role of the clock in regulation of the activity of MAPK pathways provides important clues into the function of the circadian clock as a tumor suppressor.

Novel two-step release system for the traditional Chinese medicine compound Danshen

A novel two-step release system for the traditional Chinese medicine compound Danshen was developed by combining an effervescent osmotic pump tablet (EOPT) and a pulsed-released tablet (PT) of compound Danshen into one hard capsule. The EOPT of Danshen was prepared with sodium chloride, mannitol, hydroxypropylmethylcellulose (HPMC), and sodium bicarbonate as osmotic agents. The osmotic pressure from EOPT was greatly enhanced by carbon dioxide generated from the reaction between sodium bicarbonate and acidic components from Danshen. It was shown that the tested Danshen components could be completely released from the prepared EOPT following a zero-order release for up to 12 h. The PT of compound Danshen was a three-layer coated tablet composed of organic acid and osmotic agents. Eudragit RL, HPMC and the mixture of EC and Eudragit RS, RL were the major constituents of the separation layer, swelling layer and controlling release membrane, respectively. The swelling test of the PT indicated that swelling is a prerequisite for drug release from this PT device. In addition, the swelling behavior further suggested the drug release mechanism of PT involves diffusion, the osmotic pumping effect, and organic acid-induced effect, among which the osmotic pumping effect was the most important. Moreover, there was no significant difference among the five active constituents in their release profiles from the final combined two-step release system of compound Danshen.

Chronomics for chronoastrobiology with immediate spin-offs for life quality and longevity

Effects of geomagnetic disturbance on heart rate variability (HRV), the 1/f fractal scaling in particular, are being assessed in adults living at high latitude, where magnetic storms are more frequent and more intense than at lower latitudes. The latter may constitute a signal or a proxy, and possibly a mechanism underlying both undesirable and desirable effects, depending upon circumstances yet to be elucidated. Any circadecadal stage-dependence of morbidity and/or mortality from certain conditions such as myocardial infarctions remains to be studied in both adult and pediatric populations. Further work could thus examine whether any associations of geomagnetic disturbances may account, at least in part, through effects upon the circulation, for long-term infra-annual changes, possibly anchored in the population's gene pool, observed in a number of anthropologic measurements at birth as well as in other population statistics. In order to assess the development of several chronome components of the electrocardiogram (ECG), around-the-clock ambulatory ECG were recorded from 19 infants (25 days-3 months of age), 22 children (3-9 years of age), 18 boys and girls (10-14 years of age), pubertal boys (15-20 years of age), and 10 young men (21-29 years of age). Time- and frequency-domain measures of HRV were obtained by spectral analysis, using the maximal entropy method (MEM). The frequency of detection of the circadian, circasemidian and circaoctohoran components, with periods of about 24, 12 and 8 h, respectively, was compared among the five groups for several HRV endpoints, notably 1/f fractal scaling, total spectral power within a 5-min span, and its distribution into several frequency regions. A circadian component is already detectable in a sizeable proportion of infants and children for most of the HRV indices considered. The incidence of detection of the circadian component increases with age for the spectral power in different frequency regions, notably around 10.5 s ("LF") and around 3.6 s ("HF"); it peaks around puberty for 1/f in our data; and it did not detectably change with age for the total spectral power. Similar changes with age are not observed for the circasemidian or circaoctohoran components. The latter characterizes primarily 1/f and less so the about 3.6 s power ("HF"). Several aspects of the HRV chronome may thus develop differently as a function of age. In 2000, we began a community-based study named "Longitudinal Investigation of Longevity and Aging in Hokkaido County (LILAC study)". The ambulatory blood pressure (BP) of middle-aged subjects, aged 40-74 years, was monitored 7-day/24-h, and the cardiovascular and neurobehavioral functions of elderly people above 75 years were evaluated. Our goal was the prevention of stroke and myocardial infarction and the decline in cognitive function of the elderly in a community. Of 115 elderly people recruited in a longitudinal community-based study in 2000, 72 completed yearly follow-ups in 2002. A cardiovascular score based on BP, pulse wave velocity, and 1-h ECG-based HRV endpoints served to distinguish between normal, mildly disordered, or disordered participants. A comparison of cognitive function in 2002 vs. 2000, assessed with the MMSE, HDSR, the Up & Go and Functional Reach tests, gauged any effect of social intervention. Cognitive function was maintained or improved, especially for people suffering from hypertension, tachycardia, or a decreased HRV, suggesting that cardiovascular function is a major factor affecting cognitive function.