Showing papers in "Biological Rhythm Research in 2007"
TL;DR: Various procedures used in the analysis of circadian rhythms at the populational, organismal, cellular and molecular levels are reviewed.
Abstract: This article reviews various procedures used in the analysis of circadian rhythms at the populational, organismal, cellular and molecular levels. The procedures range from visual inspection of time plots and actograms to several mathematical methods of time series analysis. Computational steps are described in some detail, and additional bibliographic resources and computer programs are listed.
583 citations
TL;DR: In this article, the structure of the 72-item Sleep Wake Pattern Assessment Questionnaire (SWPAQ) fits to a theorized circular model, and the results of the analysis of correlations among the subdimensions of the SWPAQ indicate that the questionnaire exhibits a clear three-dimensional circumplex structure in accord with the theoretical expectations, and that deviations from this structure appear to be random.
Abstract: In a search for the natural structure of the sleep – wake adaptability, the questionnaire data (total n = 680) were analysed to examine whether the structure of the 72-item Sleep Wake Pattern Assessment Questionnaire (SWPAQ) fits to a theorized circular model. The tetra-circumplex criterion was introduced to measure the extent of deviation of the SWPAQ structure from the structure of the sleep – wake adaptability predicted by the three-dimensional (cube-in-globe) model (Putilov & Putilov 2005). The results of the analysis of correlations among the subdimensions of the SWPAQ indicate that these subdimensions might be configured into four two-dimensional circumplex-like shapes. This means that, at least in general, the questionnaire exhibits a clear three-dimensional circumplex structure in accord with the theoretical expectations, and that the deviations from this structure appear to be random. It was concluded that this finding provides empirical evidence of similarity between the actual and theo...
35 citations
TL;DR: There is sound evidence that “time-of-day” has to be included in the authors' diagnostic and therapeutic strategies and different types of drugs may be superior to others when circadian time-related symptoms are concerned.
Abstract: The cardiovascular system is well organized in time. Mechanisms of regulation and pathophysiological events are not evenly distributed over the 24-h scale. Moreover, certain diseases may even alter...
35 citations
TL;DR: Although the results of the present study corroborate with the most of the earlier findings in terms of dominancy of intermediate trait, it does not support those identical reports where the prevalence of morningness or eveningness is concerned.
Abstract: The aim of the present study was to investigate morningness – eveningness preference in Indian school students as function of gender, age and habitat. A random sample of 2742 school students, consisting of 1487 males and 1255 females, participated in the study. They were divided into four clusters on the basis of their age, i.e. 8 – 11 y, 12 – 15 y, 16 – 19 y, and 20 – 23 y. In addition they were further categorised into two groups on the basis of their place of abode (habitat), i.e. city versus rural. Each student was classified either as morning type (MT) or evening type (ET) or intermediate type (IT) on the basis of his/her performance on a Lark-Owl test, a type of morningness – eveningness questionnaire (MEQ). Prevalence of MT, IT and ET in the studied population was 35.34% (969), 62.73% (1720) and 1.93% (53), respectively. The males and females differed significantly on their mean scores (p < 0.05), i.e. the former group had a higher score as compared with the latter group. The prevalence of...
29 citations
TL;DR: This article explored whether circadian preference is related to students' attitudes and choices to attend lectures or watch them online, and whether these variables relate to course performance, and found that evening-type students were significantly more likely to have a positive attitude toward online lectures and to choose to watch lectures online.
Abstract: This study explored whether circadian preference is related to students' attitudes and choices to attend lectures or watch them online, and whether these variables relate to course performance. The subjects were 847 students enrolled in an introductory psychology course who completed an online survey that contained the Morningness – Eveningness Questionnaire and that ascertained their attitudes towards online lectures and the extent to which they attended lectures or watched them online; course performance was also recorded. The results revealed that evening-type students were significantly more likely to have a positive attitude toward online lectures and to choose to watch lectures online. Course performance was not linked to morningness – eveningness preference, lecture mode choice, or their interaction. The results suggest that online lectures appeal differentially to students with a morning or evening orientation, but that watching lectures in a modality that does not accommodate a student's...
25 citations
TL;DR: The results suggest the influence of external stimuli, such as feeding time, on the rhythmic pattern of the metabolites involved in liver function and the hypothetic interaction between circadian clocks placed in the liver and the mean circadian system is suggested.
Abstract: Many physiological processes of domestic animals exhibit daily rhythmicity. The goal of the present study was to investigate, in cows, the influence of different schedules of feeding on daily rhythms of blood urea and ammonia concentrations. Fifteen Italian Brown cows, from the same farm, clinically healthy and placed at the same environmental temperature and photoperiod, were used for this study. Thirty days before the experiment, all the subjects were divided into three homogeneous groups of five cows: A group was fed at 08.00, B group was fed at 16.00, both having access to food for two hours (A group 08.00 – 10.00; B group 16.00 – 18.00) and C group was fed ad libitum. Blood samples were collected at four hour intervals for 72 consecutive hours starting at 08.00 of the first day and finishing at 04.00 of the third day via intravenous cannula inserted into the jugular vein. On each serum, blood urea and ammonia concentrations were assayed. Data analysis was conducted by one-way repeated measur...
24 citations
TL;DR: In this paper, the behavior of growing pigs housed on two different commercial farms was studied to analyse daily rhythms related to behaviour, and the existence of a periodic pattern in most of the behaviours was verified with a mathematical model, demonstrating substantial differences between the models obtained for each farm.
Abstract: The behaviour of growing pigs housed on two different commercial farms was studied to analyse daily rhythms related to behaviour. During the hot summer in Castilla La Mancha (Spain), 25 pigs were used, 10 from the first farm and 15 from the second one, so as to be able to work with the same stocking density (0.75 m2/pig). Their behaviours were recorded for 16 days in two separate periods with a video camera and subsequently observed for studying one photogram every 10 minutes (2035 observations for each farm), in which six predominant behaviours were assessed. The existence of a periodic pattern in most of the behaviours was verified with a mathematical model, demonstrating substantial differences between the models obtained for each farm.
23 citations
TL;DR: It is likely that the events in the persons comprising the population and clinical case studies were influenced by ongoing treatment with antihypertensive, anticoagulant, and antianginal medications, and details regarding the class, dose, and schedule of such medications are rarely if ever reported in accounts of IHD events.
Abstract: Population-based epidemiology and clinical case studies document a prominent 24-hour pattern in the occurrence of silent and non-silent angina pectoris (AP), acute myocardial infarction (AMI), and sudden cardiac death (SCD). When the data are summarized per 3 – 6 hour intervals of the 24 hours, the temporal pattern of these ischemic heart disease (IHD) events shows a single morning peak between 06:00 and 12:00 h in incidence. However, when the occurrence of such events is examined according to the hour of their occurrence, several studies reveal a second late-afternoon/early-evening minor peak. The true day – night pattern in AP, AMI, and SCD is unknown because the data represent nothing more than the recorded “time of day” of the events. It has been postulated that the day – night pattern in IHD events is at least in part dependent on endogenous circadian rhythms, which are synchronized by the daily routine of sleep in darkness/activity in light. Approximately 20% of the working population is in...
22 citations
TL;DR: Circadian, weekly, and seasonal patterns of occurrence of acute myocardial infarction, along with their underlying pathophysiological triggering factors are reviewed.
Abstract: Convincing evidence has demonstrated that cardiovascular diseases do not occur randomly throughout the day, the week, or the year but show a well defined temporal organization. This article will review circadian, weekly, and seasonal patterns of occurrence of acute myocardial infarction, along with their underlying pathophysiological triggering factors.
17 citations
TL;DR: Based upon data from several sources, including night work, resting subjects and bed-ridden patients, it is concluded that the contribution of the “body clock” to producing the circadian rhythm in heart rate and blood pressure is relatively small.
Abstract: The development of ambulatory blood pressure monitoring devices and the beat-by-beat measurement of heart rate have enabled it to be established that there are circadian rhythms in heart rate and blood pressure in subjects living normally. Investigations of these variables have led to quantification of their fall at night, and rapid rise on awakening and becoming active in the morning. These changes are of particular interest insofar as abnormalities in them are associated with cardiovascular problems and morbidity in patients and also act as risk factors in otherwise healthy individuals. It has also been shown that there are many other variables of the cardiovascular system. The causes of the circadian rhythms in heart rate and blood pressure are outlined, with particular stress upon the role of the autonomic nervous system, as assessed from low- and high-frequency components of the variation in heart rate measured beat-by-beat. Activity increases blood pressure, but there is evidence that this ...
14 citations
TL;DR: In this paper, the authors investigated the time of night effect on prospective time estimation efficiency and found that morning-types tended to produce significantly shorter time intervals and less time estimation accuracy than evening-types.
Abstract: The aim of the present study was to investigate the time of night effect on prospective time estimation efficiency. Fifty-four participants took part in six consecutive experimental sessions from 10:00 p.m. to 8:00 a.m. at intervals of 2 h, during which they had to carry out two kinds of tasks (simple reaction time and prospective time estimation), give an evaluation of their subjective alertness, and record body temperature. In agreement with previous data on body temperature, subjective alertness and performance in simple reaction time showed a significant decrease during the night, while performance in prospective time estimation did not change over the night. Taking into account circadian typology we found that morning-types tended to produce significantly shorter time intervals and less time estimation accuracy than evening-types. With reference to recent cognitive timing models and data derived from free-running conditions, it is hypothesised that internal pace-makers pulse at different rat...
TL;DR: The biological rhythms of a number of functions involved in acute myocardial infarction e.g. blood pressure, hormonal determinants, cholesterol, among others are pointed out.
Abstract: Almost all cardiovascular events occur according to a circadian rhythm with a greater frequency in the morning on waking and when resuming activity, the mechanism and precise triggering events for myocardial infarction (MI) are not yet fully known. Multiple biologic functions show a diurnal and/or seasonal variation that may contribute to adverse cardiac outomes. Exogenous factors may also modulates these variations. The MI peak usually occurs between 07:00 and 12:00 h. This timing corresponds to the concurrent increase in platelet aggregability, blood concentration of cortisol, catecholamines, angiotensin II, myocardial oxygen demand and coagulation activity, while fibrinolytic activity is decreased. In this review paper we will point out the biological rhythms of a number of functions involved in acute myocardial infarction e.g. blood pressure, hormonal determinants, cholesterol, among others.
TL;DR: Along with testosterone, melatonin acts like a major temporal synchronizer to maintain not only the reproductive rhythm but also daily immune adaptability of this avian species.
Abstract: Daily variation of plasma melatonin affects daily activity pattern of many birds, but daily immunoprotective activity of melatonin in any seasonally breeding avian species is lacking. We report the influence of endogenous melatonin and testosterone on the daily variation in immunity of the Indian tropical bird Perdicula asiatica during reproductively active (RAP) and inactive (RIP) periods when the level of melatonin was high and in the former case. Daily variation in levels of melatonin, testosterone and immune parameters was noted during RAP and RIP. Maximum immune activity was noted at 2:00 hrs during RAP and at 14:00 hrs during RIP. During RAP, high testosterone in the circulation suppressed melatonin levels and immune parameters. A high basal level of melatonin during RIP was responsible for the suppression of testosterone resulting in high immune activity. Therefore, along with testosterone, melatonin acts like a major temporal synchronizer to maintain not only the reproductive rhythm but a...
TL;DR: It is suggested that annual variation in cortisol in common marmosets is influenced by temperature and rainfall and might be associated with the mating season.
Abstract: In contrast to numerous studies showing breeding seasonality for animals living in temperate zones, few have addressed the effect of annual environmental changes on hormones and behavior related to reproduction for animals living in tropical and equatorial regions. In order to expand information on other primates living near the equator, we used 13 adult common marmosets, eight males and five females living under natural climatic conditions in a colony located in North-Eastern Brazil. Blood samples were collected monthly from July 2002 to June 2004. Cortisol assays were performed by ELISA. Cortisol levels varied according to environmental temperature and rainfall but were not significantly affected by photoperiod. After separating out these environmental effects through an analysis of covariance for repeated measurements, a marginal significant difference in cortisol levels according to the seasons of the year was detected. A significant difference in cortisol levels between females and males was...
TL;DR: A mathematical model to describe post-translational oscillations and the possible chemical reactions involved in the circadian clock mechanism of cyanobacteria is developed and it is demonstrated that the mathematical system can lead to circadian oscillation within a range of parameter values.
Abstract: Cyanobacteria are the simplest organisms known that exhibit circadian rhythms. The mechanism of circadian rhythm generation in cyanobacteria is different from eukaryotes. Based on the recent experiments about the interaction of KaiA, KaiB, and KaiC proteins with the generation of circadian rhythms in vitro, we developed a mathematical model to describe post-translational oscillations and the possible chemical reactions involved in the circadian clock mechanism of cyanobacteria. In this model, a series of differential equations, with linear kinetics for binding of proteins, Michaelis – Menten kinetics for enzymatic processes and a term including an explicit delay for dissociation of the KaiA/KaiB/phospho-KaiC complex, are proposed describing the dynamics of the chemistry. It is demonstrated that the mathematical system can lead to circadian oscillation within a range of parameter values.
TL;DR: In this paper, the parameters of Drosophila ananassae strains originating from the equator, 0°N to 22.29°N were variable and latitude dependent.
Abstract: Parameters of oviposition rhythm of Drosophila ananassae strains originating from the equator, 0°N to 22.29°N were variable and latitude dependent. Phase angle difference (Ψ), amplitude of rhythm (R) and the percent oviposition in photophase (POP) were determined in LD 12:12 cycles. Although the R did not vary, the Ψ and POP varied by ∼5 h and 60, respectively. Ψ was positively correlated while the POP was negatively correlated with latitude. Transfers from LD 12:12 cycles to constant darkness initiated free-running rhythms in all strains. Although the R did not vary, the τ varied by ∼3.5 h which was positively correlated with latitude.
TL;DR: The chronobiology of acute myocardial infarction is reviewed from the viewpoint of molecular biology to show that this circadian oscillation is closely related to the function of the internal biological clock.
Abstract: The incidence of heart attacks increases in the early morning. This circadian oscillation is closely related to the function of the internal biological clock. In this article, we review the chronobiology of acute myocardial infarction (AMI) from the viewpoint of molecular biology.
TL;DR: The data show the negative correlation over time between leptin and cortisol (r = −0.28, p = 0.005), and it is demonstrated that leptin and insulin are not correlated over time.
Abstract: The recent discovery of leptin, the product of the “ob” gene has greatly advanced the understanding of body adiposity and energy balance regulation. Serum leptin levels follow a circadian rhythm, which seems to be regulated predominantly by insulin increases levels and the circadian rhythm of cortisol. The aims of this study were to: (1) determine the effect of obesity on leptin 24 hours pattern; (2) determine the biological rhythm of leptin, insulin and cortisol. Thirteen subjects (10 women, three men) participated in this study. Serum samples were drawn at four hour intervals for a total of 24 hours. Leptin showed diurnal rhythmicity with peaks at 04.00 h (91.7±12.9 ng/ml) and troughs at 12.00 h (73.1±9.7 ng/ml). There was a strong association between leptin levels and BMI (r = 0.34; p < 0.001). The high levels of leptin may contribute to leptin resistance in obesity. Our data show the negative correlation over time between leptin and cortisol (r = −0.28, p = 0.005), and we demonstrate also tha...
TL;DR: In this paper, the authors found that increased lipid peroxidation and liver marker enzymes are associated with decreased activities of antioxidants (decreased mesor of GPx, GSH, SOD and CAT) in hyperammonemic rats.
Abstract: Circadian variations of lipid peroxidation products: thiobarbituric acid and reactive substances (TBARS), antioxidants: reduced glutathione (GSH), superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT) and liver marker enzymes such as transaminases (aspartate transaminase (AST) and alanine transaminase (ALT), alkaline phosphatase (ALP) and γ-Glutamyl transpeptidase (GGT) in circulation were analysed in control and ammonium chloride (AC) induced (100 mg/kg bodyweight) hyperammonemic rats. Elevated lipid peroxidation and liver marker enzymes (increased mesor of TBARS, AST, ALT, ALP and GGT) associated with decreased activities of antioxidants (decreased mesor of GPx, GSH, SOD and CAT) were found in hyperammonemic rats. Variations in acrophase, amplitude and r values were also found in between the control and hyperammonemic rats. These alterations clearly indicate that temporal liver marker enzymes and redox status are modulated during hyperammonemic conditions, which may also play...
TL;DR: In this article, the parameters of light pulse induced phase response curves (PRCs) for the circadian rhythm of oviposition in three latitudinal strains of Drosophila ananassae originating from 0°N on the equator at Pontianak (the PK strain), 11.94°N at Kannur (the KR strain) and 22.29°n at Dwaraka (the DA strain) were variable and latitude dependent.
Abstract: Parameters of light pulse induced phase response curves (PRCs) for the circadian rhythm of oviposition in three latitudinal strains of Drosophila ananassae originating from 0°N on the equator at Pontianak (the PK strain), 11.94°N at Kannur (the KR strain) and 22.29°N at Dwaraka (the DA strain) were variable and latitude dependent. The PRC for the PK strain had a low amplitude, dead zone of 8 h and the ratio for the advance to delay region (A/D) 1, while the PRC for the KR strain had intermediate values for these parameters. Thus, the lower latitude was correlated with low amplitude and protracted dead zone in the PRC for oviposition rhythm of D. ananassae.
TL;DR: D-aspartate was used to demonstrate possible sources of excitatory input to the suprachiasmatic nucleus (SCN) in rats and altered biochemical rhythms in aspartate treated rats could be due to modulation of neurotransmission in SCN, behavioural rhythms and (3) feeding rhythms.
Abstract: D-aspartate was used to demonstrate possible sources of excitatory input to the suprachiasmatic nucleus (SCN) in rats. Aspartate (50 mg/kg bodyweight) was orally administrated chronically for 60 days to Wistar rats and 24 h rhythmic patterns of glucose, cholesterol, total protein and aspartate transaminase (AST) were studied under light – dark (LD 12:12 h) cycle. Our results showed acrophase advances in glucose and delays in cholesterol and AST rhythms. Increased mesor and altered amplitude values were found in all rhythms; aspartate levels in the brain were found to be significantly increased in aspartate treated animals. We hypothesised that the altered biochemical rhythms in aspartate treated rats could be due to (1) modulation of neurotransmission in SCN, (2) behavioural rhythms and (3) feeding rhythms.
TL;DR: Medication such as beta-blockers and aspirin may lower the increased risk of coronary events during exposure to external triggers and further research is needed with regard to psychosocial stressors and their potential role as external triggers of myocardial infarction and other coronary events.
Abstract: Coronary heart disease is one of the leading causes of death in both industrialised and developing countries. About two thirds of all coronary deaths occur outside the hospital and before any medical care can be reached. Therefore, the prevention of coronary events appears to be of utmost importance. Rupture of an atherosclerotic plaque and subsequent coronary thrombosis is the most common underlying pathophysiological mechanism of coronary events. External stresses or ‘triggers’ imposing on coronary plaques may precipitate plaque rupture. External triggers include physical activity, various emotional stresses, eating, environmental factors, and sexual activity. The increased relative risk of myocardial infarction may be induced by external triggers via the activation of internal triggering mechanisms such as biomechanical and hemodynamic stresses and changes in platelet aggregability and blood viscosity. Recent prospective studies have confirmed the results of earlier retrospective studies and h...
TL;DR: A solution of the long-lived enigma of Lake Baikal, the so-called “melosira years” phenomenon, is presented to reveal 3⅔, 7⅓, and 11(10, 12)-year cycles in the interannual phytoplankton dynamics and their regulation by solar activity.
Abstract: The paper presents a solution of the long-lived enigma of Lake Baikal, the so-called “melosira years” phenomenon. Lake Baikal exhibits sharp differences in its spring phytoplankton development of up to hundred times from year to year. Intervals between these bloom outbursts are, as a rule, 3 and 4 years long but they were sometimes doubled, and sometimes they arrived in a year or in other year. An analysis of the “melosira years” sequence enabled us to reveal 3⅔, 7⅓, and 11(10, 12)-year cycles in the interannual phytoplankton dynamics and their regulation by solar activity. This regulation is in that algae can skip from cycle to cycle in dependence of the solar activity level in its maximum. When a solar cycle shortens as the 23rd solar activity cycle did, spring baikalian phytoplankton also shorten their basic 11-year cycle to 10-year one. The solution is verified by a prediction of future “melosira years”.
TL;DR: The dynamics of salivary testosterone showed high intra-individual variability in both genders and ANORVA II analysis showed no significant rhythms, although a weak circaseptan cyclic pattern has been found in women.
Abstract: Background. The dynamics of testosterone levels exhibits several cyclic patterns with various period lengths. Circadian and circannual rhythms of testosterone are known in both genders. Among infradian rhythms only the circalunar cycle in women is widely accepted. In our previous studies we have found a circatrigintan (30 days) and a circavigintan (20 days) cycle in men. Whether cyclic patterns with higher frequencies are present in the dynamics of testosterone levels in men or in women is unknown. Aim. To analyze the infradian dynamics of salivary testosterone in both genders for the presence of cyclic patterns. Subjects and methods. Seventeen young and healthy women and 15 men were asked to collect saliva samples during 30 consecutive days. Testosterone levels were determined using radioimmunoassay, Analysis of Rhythmic Variance II (ANORVA II) was used for statistical analysis. Potential period lengths of 3 – 15 days were evaluated. Results. The dynamics of salivary testosterone showed high int...
TL;DR: There is a modulating effect of the arousing experience in the pool on the overt circadian rhythm of locomotor activity, which is equivalent to an intense post-training bout of activity in the animals tested during their inactive phase.
Abstract: Wistar rats maintained in cages with running wheels and submitted to a skeleton photoperiod or to a light – dark cycle were tested in the Morris water maze. Half of the animals were exposed to the task during their active phase while the other half was exposed during their inactive phase. The effect of the experience in the water maze, a strong arousing event, on the rhythm of wheel-running activity was evaluated. In the first experiment, a group of animals submitted to a skeleton photoperiod was trained every day in the reference memory version of the task. The novel experience in the water maze had a strong phase-dependent masking effect: it produced an intense post-training bout of activity in the animals tested during their inactive phase. Another experiment was run using single working memory sessions in the water maze and with animals submitted to a light – dark cycle. The circadian rhythm of locomotor activity was evaluated on undisturbed days and compared with testing days. The experience...
TL;DR: The results in the present investigation revealed that the wild plants upon which camels usually feed contain a significant amount of melatonin, which could be one of the factors causing an increase in the level ofmelatonin in the blood and consequently influencing testicular regression during the non-rutting season.
Abstract: We studied the sites of melatonin synthesis which was measured using the radioimmunoassay technique in the eye retina, skin, Harderian gland, liver tissue and jejunal mucosa in the immature and mature (non-rutting and rutting) Camelus dromedarius For the first time, melatonin hormone was found in extrapineal sources in camel These sites included the retina, skin, Harderian gland, liver and jejunal mucosa The levels of melatonin in these sites reached 807, 335, 846, 5489 and 20241 pg/mg, respectively, in the immature camel In the mature non-rutting camel, during the non-mating season, the level of melatonin was estimated at 737, 411, 863, 19426 and 441120 pg/mg, respectively, giving a generally high level In the mating rutting camel during the winter season, the melatonin level exhibited a level of 772, 395, 820, 9309 and 146440 pg/mg, respectively, with an indication of a general decrease with the exception of the retinal melatonin when compared to the non-rutting camel It sh
TL;DR: The circadian transient risk state for myocardial infarctions and other thromboembolic events during the morning hours in diurnally active subjects has to be recognized and may be amenable to possible prevention.
Abstract: The occurrence of acute ischemia in the coronary circulation, leading to myocardial infarction and sudden cardiac death and numerous other thromboembolic events in different areas of the body, follows a circadian periodic pattern. This pattern is characterized by a major peak in the morning. Numerous circadian rhythms in different compartments of the hemostatic system contribute to this characteristic pattern. The temporal coincidence of vascular rhythms favoring impairment of the coronary circulation, with a morning increase in the activity of platelets in response to stimulation with a hypercoagulable state and a circadian minimum in fibrinolysis, leads to the increased incidence of thromboembolic events at that circadian stage. Direct circadian clock-dependence has been shown for some rhythms, e.g. in fibrinolysis, and circadian rhythm disturbances may favor coronary artery pathology. The circadian transient risk state for myocardial infarctions and other thromboembolic events during the morni...
TL;DR: It is suggested that normal circadian rhythms of pineal hormones are regulated by pulse dark phase in normal rats, and lithium abolishes pineal hormonal rhythm only in pulse light but sustains it in constant dark phase, while testosterone rhythm was abolished after lithium treatment in normal (L:D)/reversed L:D (D:L) cycle or even in constant light/dark.
Abstract: The aim of the current investigation was to study the effect of lithium on circadian rhythms of pineal – testicular hormones by quantitations of pineal and serum serotonin, N-acetylserotonin and melatonin, and serum testosterone at four time points (06.00, 12.00, 18.00 and 24.00) of a 24-hr period under normal photoperiod (L:D), reversed photoperiod (D:L), constant light (L:L) and constant dark phase (D:D) in rats. Circadian rhythms were observed in pineal hormones in all the combinations of photoperiodic regimens, except in constant light, and in testosterone levels in all the photoperiodic combinations. Pineal and serum N-acetylserotonin and melatonin levels were higher than serotonin at night (24.00 hr), in natural L:D cycle, in reversed L:D cycle or similar to normal L:D cycle in constant dark phase, without any change in constant light. In contrast, testosterone level was higher in light phase (12.00 hr through 18.00 hr) than in the dark phase (24.00 hr through 06.00 hr) in normal L:D cycle,...
TL;DR: The definitive answer of a circannual rhythm of births in patients with ulcerative colitis or Crohn’s Disease remains open.
Abstract: Seasonal distribution of birth dates in patients with ulcerative colitis (CU) or Crohn’s Disease (CD) has been investigated with different results in the past (Toft et al. 2001; Card et al. 2002). Whereas Card et al. (2002) found no significant seasonality of inflammatory bowel disease in Britain, Toft and Pederson’s analysis (Toft et al. 2001) revealed a peak of births in late summer and early fall in a Danish population with Crohn’s disease. Amyotrophic lateral sclerosis (ALS) yielded an excess of births from April to July in population based on studies both in Switzerland and Japan (Kimura and Miura 1983; Kondo and Fujiki 1984); however this seasonality of births in ALS patients was not confirmed in another Japanese investigation (Ajdacic-Gross et al. 1998). Therefore, the definitive answer of a circannual rhythm of births in these patients remains open.
TL;DR: The detectable circadian rhythms of hepatic marker enzymes and their alterations during AC/PPEt treatments, in the present study, deserve further investigation for the diagnosis and for the therapeutic efficacy of hyperammonemia.
Abstract: In this study, the influences of Pongamia pinnata, an indigenous medicinal plant used in Ayurvedic and traditional Medicine in India, on the circadian variations of liver marker enzymes in ammonium chloride (AC) induced hyperammonemic rats were studied. Experimental rats (160 – 180 g) were divided into control, AC (daily i.p. injection of AC (100 mg kg−1 body weight)) treated, AC + P. pinnata ethanolic leaf extract (PPEt) (300 mg kg−1 body weight) treated and PPEt treated groups. Temporal characteristics (acrophase, amplitude and mesor) of liver marker enzymes; alkaline phosphatase (ALP), aspartate and alanine transaminases (ALT and AST) and γ-glutamyl transferase (GGT) were analyzed. Elevated liver marker enzymes (increased mesor and delayed acrophase of AST, ALT, ALP and GGT) were found in hyperammonemic rats. Administration of PPEt significantly alters these changes. Variations in acrophase, amplitude and r values were also found in control and experimental rats. The detectable circadian rhyth...