2-years retrospective observational case-control study on survival and marginal bone loss of implants in patients with hereditary coagulopathies.

BACKGROUND: Evaluating 2-years implant loss and marginal bone loss in patients with hereditary coagulopathies, comparing with a healthy control group. MATERIAL AND METHODS: 37 implants in 13 patients (17 haemophilia A, 20 Von-Willebrand disease) versus 26 implants in 13 healthy patients. Data measured through Lagervall-Jansson index (after surgery, at prosthetic loading, at 2 years). STATISTICS: Chi-square, Haberman's, ANOVA, Mann-Whitney-U. Significance p<0.05. RESULTS: Haemorrhagic accidents in 2 coagulopathies patients (non-statistical differences). Hereditary coagulopathies patients suffered more hepatitis (p<0.05), HIV (p<0.05) and less previous periodontitis (p<0.01). Non-statistical differences in marginal bone loss among groups. 2 implants were lost in the hereditary coagulopathies and none in the control group (non-statistical differences). Hereditary coagulopathies patients had longer (p<0.001), and narrower implants (p<0.05) placed. 43.2% external prosthetic connection in hereditary coagulopathies patients (p<0.001); change of prosthetic platform more frequent in control group (p<0.05). 2 implants lost: external connection (p<0.05). Survival rate 96.8% (hereditary coagulopathies 94.6%, control group 100%). CONCLUSIONS: Implant and marginal bone loss at 2 years is similar in patients with hereditary coagulopathies and control group. Precautions should be taken on the treatment for hereditary coagulopathies patients, through prior haematological protocol. Implant loss only occurred in in a patient with Von-Willebrand´s disease.

Meal timing affects glucose tolerance, substrate oxidation and circadian-related variables: A randomized, crossover trial.

BACKGROUND/OBJECTIVES: Timing of food intake associates with body weight regulation, insulin sensitivity and glucose tolerance. However, the mechanism is unknown. The aim of this study was to investigate the effects of changes in meal timing on energy-expenditure, glucose-tolerance and circadian-related variables. SUBJECTS/METHODS: Thirty-two women (aged 24±4 years and body mass index 22.9±2.6 kg m(-2)) completed two randomized, crossover protocols: one protocol (P1) including assessment of resting-energy expenditure (indirect-calorimetry) and glucose tolerance (mixed-meal test) (n=10), the other (P2) including circadian-related measurements based on profiles in salivary cortisol and wrist temperature (Twrist) (n=22). In each protocol, participants were provided with standardized meals (breakfast, lunch and dinner) during the two meal intervention weeks and were studied under two lunch-eating conditions: Early Eating (EE; lunch at 13:00) and Late Eating (LE; lunch 16:30). RESULTS: LE, as compared with EE, resulted in decreased pre-meal resting-energy expenditure (P=0.048), a lower pre-meal protein-corrected respiratory quotient (CRQ) and a changed post-meal profile of CRQ (P=0.019). These changes reflected a significantly lower pre-meal utilization of carbohydrates in LE versus EE (P=0.006). LE also increased glucose area under curve above baseline by 46%, demonstrating decreased glucose tolerance (P=0.002). Changes in the daily profile of cortisol and Twrist were also found with LE blunting the cortisol profile, with lower morning and afternoon values, and suppressing the postprandial Twrist peak (P<0.05). CONCLUSIONS: Eating late is associated with decreased resting-energy expenditure, decreased fasting carbohydrate oxidation, decreased glucose tolerance, blunted daily profile in free cortisol concentrations and decreased thermal effect of food on Twrist. These results may be implicated in the differential effects of meal timing on metabolic health.

Circadian rhythmicity as a predictor of weight-loss effectiveness.

OBJECTIVES: Some of the major challenges associated with successful dietary weight management include the identification of individuals not responsive to specific interventions. The aim was to investigate the potential relationship between weight loss and circadian rhythmicity, using wrist temperature and actimetry measurements, in women undergoing a weight-loss program, in order to assess whether circadian rhythmicity could be a marker of weight-loss effectiveness. METHODS: Participants were 85 overweight and obese women (body mass index, BMI: 30.24±4.95 kg m(-2)) subjected to a weight-reduction program. Efficacy of the treatment was defined as total weight loss, percentage of initial weight and weekly weight loss rates. Circadian rhythmicity in wrist temperature motor activity and position were analyzed using different sensors. RESULTS: Lower weight loss was related with a more flattened pattern measured as amplitude from cosinor (r=0.235, P=0.032), a higher fragmentation of rhythms determined by higher intradaily variability (IV) (r=-0.339, P=0.002), and an impaired wrist temperature circadian rhythm determined by the means of Circadian Function Index (r=0.228, P=0.038). Further analyses showed that low responders displayed lower amplitude (0.71±0.36 versus 1.24±0.62, P=0.036) and higher fragmentation of the circadian rhythm (0.24±0.11 versus 0.15±0.07, P=0.043) than high responders. Whereas we did not find significant differences in total activity rates between high responders and low responders, we found significant differences for the mean values of body position for high responders (39.12±3.79°) as compared with low responder women (35.31±2.53°, P=0.01). CONCLUSIONS: Circadian rhythms at the beginning of the treatment are good predictors of future weight loss. Further treatment should consider chronobiological aspects to diagnose obesity and effectiveness of treatments.

Circadian temperature rhythm in breeding sows: differences between days in oestrus and anoestrus after weaning.

BACKGROUND: Mammals are subject to circadian rhythms for the control of various physiological events. One of the parameters known to be subject to variations throughout the day is body temperature, which is also subject to influences such as environmental temperature. However, there are not many studies on these rhythms in breeding sows. The aim of this study was to determine the circadian parameters for body temperature in post-weaning sows during oestrus period, throughout the seasons in a warm climate. RESULTS: Differences were observed in inter-daily stability, intra-daily fragmentation and cycle length comparing the summer sows with the other seasons. Differences were also observed in the period that the sows were in oestrus compared to the non-oestrus period for intra-daily fragmentation, with these differences being more important in the warm seasons compared to the cold seasons. The parameters normalised by COSINOR also showed significant differences when comparing seasons, especially in the acrophase of the temperature maximum. Another significant finding was an increase in vaginal temperature during oestrus in sows monitored in summer compared to the other seasons. Correlations between body, vaginal and environmental temperature were observed. CONCLUSION: There is a seasonal influence on the circadian rhythm of temperature and summer is clearly the season with the greatest differences in circadian parameters when compared to the other seasons. The extreme summer conditions seem to definitely influence this rhythm and make the body and vaginal temperature of the sows different from the rest of the year. The increase in period robustness in both body and vaginal temperature during the days when sows are in oestrus could be related to the hormonal events of oestrus and ovulation and seems to be independent of weather since it occurs in all controlled seasons. However, this robustness is significantly higher in summer than in the other seasons both in the oestrus period and on days when sows are not in oestrus.

Differences in circadian rhythmicity in CLOCK 3111T/C genetic variants in moderate obese women as assessed by thermometry, actimetry and body position.

INTRODUCTION: Genetics is behind our circadian machinery. CLOCK (Circadian Locomotor Output Cycles Kaput) 3111T/C single-nucleotide polymorphism (SNP) has been previously related to obesity and weight loss. However, phenotypic association and functionality of CLOCK 3111 locus is still unknown. The aim of this study was to determine, in free-living conditions, if the presence of CLOCK 3111C in overweight women could be related to (a) circadian disorders, and (b) changes in sleep quality, to improve understanding of the previously demonstrated associations with obesity and reduced weight loss of the C carriers. METHODS: Wrist temperature, actimetry and position (TAP) and TAP variables were measured as markers of circadian functionality during 8 consecutive days. A rest-activity and food diary was also completed, whereas sleep quality was determined by domiciliary polysomnography. We recruited 85 women who were overweight with body mass index (BMI) of 28.59±4.30 kg m(-2) and age 43±12 years. From this sample, we found that 43 women were carrying the minor allele (C) for CLOCK 3111T/C SNP and 42 women were TT carriers (major allele carriers). Both groups of patients were matched for number, age, obesity parameters and energy intake. RESULTS: Compared with TT subjects, who showed more robust circadian rhythm profiles, patients with the C allele displayed significant circadian abnormalities: lower amplitude and greater fragmentation of the rhythm, a less stable circadian pattern and a significantly weakened circadian function, as assessed by the circadian function index (CFI). C subjects were also less active, started their activities later in the morning and were sleepier during the day, showing a delayed acrophase that characterizes 'evening-type' subjects. CONCLUSION: C genetic variants in CLOCK 3111T/C display a less robust circadian rhythm than TT and a delayed acrophase that characterizes 'evening-type' subjects. We support the notion that identifying CLOCK genotypes in patients may assist the therapist in characterization of the roots of the metabolic problem.

Timing and duration of sleep and meals in obese and normal weight women. Association with increase blood pressure.

The aim was to evaluate the efficiency and duration of sleep and meals in normal-weight and obese women and the impact of these factors on metabolic syndrome (MetS) variables. The study was conducted in 70 women, normal-weight women (n=20) and obese women (n=50). Anthropometric variables, plasma glucose, lipids and ghrelin concentrations were determined. Blood pressure measurement was performed before lunch and before dinner for a week on alternate days. Subjects were instructed to keep a sleep and feeding diary. In general, obese women displayed longer and a significantly higher number of awakenings per week than normal-weight women and a higher duration of naps. Sleep efficiency was significantly lower in obese women. The higher intake in energy in the obese women was due to snacking differences. Moreover, higher sleep efficiency was correlated with a decrease in the diastolic blood pressure evening/morning ratio. Interestingly, among normal-weight women, visceral fat increased with the number of awakenings while plasma ghrelin was inversely correlated with meal duration (P=0.027). In conclusion, obese women had lower sleep efficiency, ate more quickly and spent more time eating and sleeping during the daytime hours than normal-weight women. Of note, sleep efficiency was associated with MetS features. Further interventions in obesity could include educating patients in food timing and in healthier sleep-hygiene practices, helping them to modify bad sleep habits.

The chronobiology, etiology and pathophysiology of obesity.

The effect of CD on human health is an emerging issue. Many records link CD with diseases such as cancer, cardiovascular, cognitive impairment and obesity, all of them conducive to premature aging. The amount of sleep has declined by 1.5 h over the past century, accompanied by an important increase in obesity. Shift work, sleep deprivation and exposure to bright light at night increase the prevalence of adiposity. Animal models have shown that mice with Clock gene disruption are prone to developing obesity and MetS. This review summarizes the latest developments with regard to chronobiology and obesity, considering (1) how molecular clocks coordinate metabolism and the specific role of the adipocyte; (2) CD and its causes and pathological consequences; (3) the epidemiological evidence of obesity as a chronobiological illness; and (4) theories of circadian disruption and obesity. Energy intake and expenditure, relevance of sleep, fat intake from a circadian perspective and psychological and genetic aspects of obesity are examined. Finally, ideas about the use of chronobiology in the treatment of obesity are discussed. Such knowledge has the potential to become a valuable tool in the understanding of the relationship between the chronobiology, etiology and pathophysiology of obesity.

CLOCK gene is implicated in weight reduction in obese patients participating in a dietary programme based on the Mediterranean diet.

INTRODUCTION: The success of obesity therapy is dependent on the genetic background of the patient. Circadian Locomotor Output Cycles Kaput (CLOCK), one of the transcription factors from the positive limb of the molecular clock, is involved in metabolic alterations. OBJECTIVE: To investigate whether five candidate polymorphisms from CLOCK were associated with anthropometric, metabolic measures and weight loss in response to a behavioural weight reduction programme based on the Mediterranean diet. METHODS: Five hundred overweight/obese subjects, aged 20-65 years, who attended outpatient clinics specializing in obesity, were studied. Anthropometric, biochemical and dietary intake variables were analysed. Effectiveness of the programme and weight loss progression during 28 weeks of treatment was assessed. RESULTS: Four of five CLOCK SNPs selected were significantly associated with obesity variables (P<0.05). The genetic variation in the rs1801260 CLOCK was associated with obesity at baseline and also affected weight loss. Patients with the variant allele (G) lost significantly less weight i(P=0.008) compared with wild type. Repeated measures analysis showed that weight loss over time was significantly different between rs1801260 CLOCK variations (P=0.038). Carriers of the G allele displayed greater difficulty in losing weight than non-carriers. In this particular polymorphism, the frequency of short-time sleepers (< or =6 h per day) was greater in minor allele carriers than in non-carriers (59% vs 41%; P<0.05). CLOCK polymorphisms were also associated with significant differences in total plasma cholesterol at the completion of dietary treatment (P<0.05). CONCLUSIONS: We have replicated previous studies showing a relationship between CLOCK gene polymorphisms and obesity. CLOCK rs1801260 SNP may predict the outcome of body weight reduction strategies based on low-energy diets.

Distinguished trajectories in time dependent vector fields.

We introduce a new definition of distinguished trajectory that generalizes the concepts of fixed point and periodic orbit to aperiodic dynamical systems. This new definition is valid for identifying distinguished trajectories with hyperbolic and nonhyperbolic types of stability. The definition is implemented numerically and the procedure consists of determining a path of limit coordinates. It has been successfully applied to known examples of distinguished trajectories. In the context of highly aperiodic realistic flows our definition characterizes distinguished trajectories in finite time intervals, and states that outside these intervals trajectories are no longer distinguished.

Clock genes are implicated in the human metabolic syndrome.

BACKGROUND: Clock genes play a role in adipose tissue (AT) in animal experimental models. However, it remains to be elucidated whether these genes are expressed in human AT. OBJECTIVE: We investigated the expression of several clock genes, Bmal1, Per2 and Cry1, in human AT from visceral and subcutaneous abdominal depots. A second objective was to elucidate whether these clock genes expressions were related to the metabolic syndrome features. METHODS: Visceral and subcutaneous AT samples were obtained from morbid obese men (n=8), age: 42+/-13 years and body mass index>/=40 kg/m(2), undergoing laparoscopic surgery due to obesity. Biopsies were taken as paired samples at the beginning of the surgical process (1100 hour). Metabolic syndrome features such as waist circumference, plasma glucose, triglycerides, total cholesterol, high-density lipoprotein cholesterol and low-density lipoprotein (LDL) cholesterol were also studied. Homeostasis model assessment index of insulin resistance was also calculated. The expression of the different clock genes, hBmal1, hPer2 and hCry1, was determined by quantitative real-time PCR. RESULTS: Clock genes were expressed in both human AT depots. hBmal1 expression was significantly lower than hPer2 and hCry1 in both AT (P<0.001). All genes were highly correlated to one another in the subcutaneous fat, while no correlation was found between Bmal1 and Per2 in the visceral AT. Clock genes AT expression was associated with the metabolic syndrome parameters: hPer2 expression level from visceral depot was inversely correlated to waist circumference (P<0.01), while the three clock genes studied were significantly and negatively correlated to total cholesterol and LDL cholesterol (P<0.01). CONCLUSION: We have demonstrated for the first time in humans that clock genes are expressed in both subcutaneous and visceral fat. Their association with abdominal fat content and cardiovascular risk factors may be an indicator of the potential role of these clock genes in the metabolic syndrome disturbances.

Effects of exogenous melatonin and circadian synchronization on tumor progression in melanoma-bearing C57BL6 mice.

Circadian rhythmicity impairment reportedly becomes significant as a tumor progresses, while the incidence of cancer can be affected by disruption of the circadian system. Melatonin has oncostatic effects on several types of cancer (breast, prostate, and colorectal cancers), while it can be self-defeating in others, such as lymphoma. Melanoma is one of the most aggressive cancers in humans; however, it seems to respond positively to melatonin in vitro. The present work tested whether body temperature (BT) rhythms are impaired by tumor progression, and whether exogenous melatonin restricts tumor growth and restores circadian rhythmicity; therefore, enhancing survival. To this end, C57 mice were intraperitoneal implanted with a temperature data logger and subcutaneously inoculated with melanoma cells. Animals were then submitted to light-dark (LD) 12:12 cycles or continuous light (LL), with or without melatonin administration. Under LD light conditions, the BT rhythm exhibited a marked reduction in the first circadian harmonic amplitude, and increased phase instability (Rayleigh vector) as the tumor progressed. Melatonin administration (2 mg/kg BW/day), on the other hand, increased the BT rhythm amplitude and phase stability, reduced tumor weight and prevented intraperitoneal dissemination. Exposure to LL induced a free-running rhythm (1500 min), significantly increasing tumor malignity, and therefore reducing survival. Surprisingly, the highest tumor weights and morbidity by metastasis were seen in the LL group treated with melatonin probably because this indoleamine was being administered at different subjective hours to free-running animals. Circadian rhythmicity can thus be used as a marker rhythm for tumor progression, as rhythm impairment increases along with tumor malignancy. While melatonin administration improves rhythmicity and enhances survival under LD conditions, the results are self-defeating when they coexist with circadian disruption as it occurs under LL. This emphasizes the importance of taking into account endogenous rhythmicity and limiting melatonin administration to the subjective night in order to restrict melanoma progression.

Role of cholecystokinin and its antagonist proglumide on macronutrient selection in European sea bass Dicentrarchus labrax, L.

Teleost fish are able to adjust their energy intake when fed on pure macronutrient sources, although the exact mechanisms regulating macronutrient selection remain unknown. Since cholecystokinin (CCK) has been reported to modify macronutrient selection patterns in mammals, we explored the effect of CCK administered orally to European sea bass on the selection of separately encapsulated macronutrients. CCK doses of 0.05, 0.15 and 0.25 mg/kg BW administered in gelatine capsules for 5 consecutive days produced a significant inhibition of total food intake (21, 28 and 51%, respectively) at highest doses, evenly reducing the quantity of all the macronutrients ingested and, without affecting their relative proportions in the diet. Oral administration of proglumide, a non-specific CCK receptor antagonist, at doses of 5, 15 and 25 mg/kg BW, induced a quantitative total food intake increase of 2, 18 and 44%, respectively, and an increase of 52% in CH and 43% in P quantity ingested at highest dose. Co-administration of proglumide (25 mg/kg BW) and CCK (0.25 mg/kg BW) in a single preload capsule blocked the effects observed with CCK alone. In conclusion, orally administered CCK induced an anorexigenic effect on both total food and single macronutrient intake, an effect that is counteracted by the CCK antagonist proglumide.

Endogenous modification of macronutrient selection pattern in sea bass (Dicentrarchus labrax, L.).

The use of a single diet with a well defined composition to feed fish throughout their life cycle is an oversimplification that probably does not respond to their metabolic requirements. For example, the seasonal reproduction that characterizes most fish species demands changes in nutritional requirements. Bearing this in mind, the macronutrient selection pattern was studied from January to August in twelve individually housed sea bass exposed to a constant photoperiod (12L:12D h) and temperature (23+/-0.5 degrees C). The endogenous "seasonal" effect on food and energy intake regulation and macronutrient selection was determined, using protein (P), carbohydrate (CH), and fat (F) packaged separately into gelatine capsules, a method that prevents the diet chemosensory properties at oropharyngeal level from interfering with macronutrient selection. Energy intake changed monthly, the highest values being recorded in May and June and the lowest values in March and April. The preliminary results illustrated "seasonal" changes in the sea bass macronutrient selection pattern with, which showed a predominantly proteinic selection during April (53% P, 21% CH, 25% F) and lipidic in July (35% P, 19% CH, 42% F); the increase in fat selection from May to July being statistically significant. This is the first evidence supporting the existence of an endogenous rhythm in the "seasonal" energy regulation and macronutrient selection in fish through post-ingestive mechanisms and probably involving chemosensory detection in the gut and/or post-absorptive mechanisms, although the exact mechanisms involved have yet to be clarified.

Circadian rhythm of wrist temperature in normal-living subjects A candidate of new index of the circadian system.

Most circadian rhythms are under the control of a major pacemaker located in the hypothalamic suprachiasmatic nucleus. Some of these rhythms, called marker rhythms, serve to characterize the timing of the internal temporal order. A marker rhythm, (e.g., one used in chronotherapy) has to be periodic and easy to measure over long periods using non-invasive methods. The most frequent reference variables for human chronotherapy include salivary melatonin or cortisol, urinary 6-sulfatoximelatonin, actimetry and core body temperature (CBT). Recent evidence suggests that sleepiness may be more closely linked to increased peripheral skin temperature than to a core temperature drop, and that distal skin temperature seems to be correlated and phase-advanced with respect to CBT, suggesting that heat loss from the extremities may drive the circadian CBT rhythm. The aim of the present study was to evaluate whether the wrist skin temperature rhythm could be used as a possible index of the human circadian system. To this end, wrist skin temperature (WT1), as determined by a wireless data logger in healthy normal living subjects, was correlated with sleep-wake diaries and oral temperature (OT) recordings. WT and sleep habits were studied in 99 university students. Each subject wore a wireless iButton sensor attached to the inner side of a sport wristband. Our results show that the WT rhythm exhibits an inverse phase relationship with OT, and it is phase-advanced by 60 min with respect to OT. WT started to increase in association to bed time and dropped sharply after awakening. A secondary WT increase, independent of feeding, was observed in the early afternoon. In conclusion, WT wireless recording can be considered a reliable procedure to evaluate circadian rhythmicity, and an index to establish and follow the effects of chronotherapy in normal living subjects.

Energy intake and macronutrient selection in sharpsnout seabream (Diplodus puntazzo) challenged with fat dilution and fat deprivation using encapsulated diets.

Sharpsnout seabream fed pure macronutrient capsules were challenged to fat dilution and fat deprivation in order to investigate the effects of fat level on energy intake regulation and macronutrient selection by fish, as they lack oropharyngeal chemosensory information from the diet. During the control phase, the fish were fed three individually encapsulated macronutrients, from which they composed a diet containing 67.36% protein (P), 19.08% carbohydrates (CH) and 13.57% fat (F), in terms of macronutrient weight intake percentage. During the second phase of the experiment, a lipid content reduction in F capsules from 55.0% to 13.4% did not significantly modify this selection pattern, energy ingestion or the number of capsules ingested of each macronutrient. During the third phase, in which they were subjected to fat deprivation, starting on almost the first day, the fish increased their total energy intake and total ingested number of capsules. These results reveal that fish are capable of distinguishing and selecting each of the three macronutrients contained in gelatine capsules, and that fish selection of a balanced diet from pure macronutrients is remarkably stable. Fish are capable of sustaining their macronutrient selection pattern and energy intake with very low amounts of fat in their diets (Phase 2). A certain instability in the initial P, CH and energy intake was only observed when fat was totally deprived (Phase 3), which resulted in higher values than those observed in Phase 1. In order to examine any possible effects of diet encapsulation, digestibility assays were performed in a second experiment. The fish were divided into two experimental groups and fed the same complete commercial diet, the only difference being the way it was presented to each group (pelleted or encapsulated). No statistical differences between the experimental groups were found with regards to both apparent digestibility coefficients and fish growth.

Circadian monitoring as an aging predictor.

The ageing process is associated with sleep and circadian rhythm (SCR) frailty, as well as greater sensitivity to chronodisruption. This is essentially due to reduced day/night contrast, decreased sensitivity to light, napping and a more sedentary lifestyle. Thus, the aim of this study is to develop an algorithm to identify a SCR phenotype as belonging to young or aged subjects. To do this, 44 young and 44 aged subjects were recruited, and their distal skin temperature (DST), activity, body position, light, environmental temperature and the integrated variable TAP rhythms were recorded under free-living conditions for five consecutive workdays. Each variable yielded an individual decision tree to differentiate between young and elderly subjects (DST, activity, position, light, environmental temperature and TAP), with agreement rates of between 76.1% (light) and 92% (TAP). These decision trees were combined into a unique decision tree that reached an agreement rate of 95.3% (4 errors out of 88, all of them around the cut-off point). Age-related SCR changes were very significant, thus allowing to discriminate accurately between young and aged people when implemented in decision trees. This is useful to identify chronodisrupted populations that could benefit from chronoenhancement strategies.

Impact of a shift work-like lighting schedule on the functioning of the circadian system in the short-lived fish Nothobranchius furzeri.

Adult Nothobranchius furzeri of the MZM-04/10 strain were individually kept and subjected to a "5 + 2" shifting lighting schedule (SHIFT) for 8 weeks in order to evaluate the desynchronizing effects of a simulated human-like shift-work schedule on the functioning of the circadian system (CS). With this aim, sixteen 21-week-old N. furzeri were placed into a Morning, Night and Evening schedule (lights on from 08:00 to 16:00, 00:00 to 08:00 and 16:00 to 00:00 h, respectively) and fed once a day in the middle of the corresponding photophase (12:00, 04:00 and 20:00 h, respectively). Then, in the weekends (2 days), fish were always returned to the Morning shift. As controls, 16 fish were maintained under a non-shifting LD cycle condition (CONTROL) throughout the whole experiment, with lights on from 08:00 to 16:00 h. Rest-activity rhythm (RAR) of fish subjected to SHIFT showed several symptoms of chronodisruption, such as a decrease in the percentage of diurnal activity and a reduction of the relative amplitude and the circadian function index with time. When a periodogram analysis was performed, RAR of N. furzeri under SHIFT conditions showed up to three separate circadian components: one longer than 24 h (26.5 h) that followed the weekly 8 h delays; a short-period component (~23 h) that was related to the weekend's phase advances, and finally, a 24 h component. The shifting LD schedule also affected fish CS at a molecular level, with several significant differences in the expression of core genes of the molecular clock (bmal1, clock, rorα, rev-erbα) between SHIFT and CONTROL animals. RAR impairment along with changes in clock gene expression could be associated with high stress and accelerated aging in these fish.

Feeding entrainment of locomotor activity rhythms, digestive enzymes and neuroendocrine factors in goldfish.

The existence of food anticipatory activity (FAA) in animals subjected to daily feeding schedules seems to be mediated by a feeding-entrainable oscillator (FEO). Such an FEO may help in anticipating meal time and so optimizing food acquisition and nutrient utilization. In this study we investigated the existence of FAA and whether digestive enzymes, plasma cortisol, hypothalamic NPY and gastrointestinal tract (GIT) and plasma melatonin were entrained by periodic feeding in goldfish. We observed that periodically fed goldfish showed FAA in locomotor activity as well as in amylase and NPY. Alkaline protease and GIT melatonin were higher after feeding, whereas plasma cortisol levels were reduced. Plasma melatonin remained unmodified before and after meal time. These results suggested that scheduled feeding entrained both behavioral and certain physiological patterns in goldfish, FAA being of adaptive value to anticipate a meal and prepare the digestive physiology of fish.

Effect of restricted feeding schedule on seasonal shifting of daily demand-feeding pattern and food anticipatory activity in European sea bass (Dicentrarchus labrax L.).

The effect of restricted feeding schedule was investigated on the seasonal shifting of daily demand-feeding pattern and food anticipatory activity in European sea bass (Dicentrarchus labrax) held under natural environmental conditions in an outdoor laboratory. To that end, demand-feeding behavior was continuously monitored for approximately one year in four groups of 15 fish each exposed to natural fluctuations of water temperature (from 13.2 degrees C to 27.4 degrees C) and photophase (from 9.5 h to 14.5 h of light). When the animals were subjected to a time-restricted feeding schedule, the demand-feeding rhythm rapidly synchronized to the three periods of food availability: the first meal (FM) from 08:00 to 09:00 h, the second meal (SM) from 16:00 to 17:00 h, and the third meal (TM) from 00:00 to 01:00 h. The occurrence of demand-feeding activity into the three periods of food availability displayed a double seasonal shift: fish that self-fed mostly during the daytime periods of feeding availability (FM and SM) in summer and autumn changed to nocturnal feeding (TM) from December to April, returning to diurnal preferences in April. Food-demands appeared to be predominantly associated with feed availability, reaching its maximum levels during the hours of reward. In addition, feeding anticipatory activity (FAA) was observed. A relationship was detected between the duration of FAA and feeding-time, with shortest FAA (30-60 min) when mealtime occurred just after sunrise (FM) or sunset (TM). These findings demonstrate the ability of sea bass to self-feed under time-restricted schedules, and show a seasonal-phase inversion in demand-feeding activity in spite of the restrictions in their feeding availability. Sea bass can use external signals as reference to anticipate the time of feed availability. This information may be useful for designing new feeding strategies for European sea bass fish farming.

Heritability of siesta and night-time sleep as continuously assessed by a circadian-related integrated measure.

Siesta is a relevant aspect of sleep due to its posited relationship with health or cognitive function. However, unlike night-time sleep, studies about daytime-sleep determinants and characteristics are scarce, and the genetic/environmental structure of siesta is still unknown. Our aim was to explore the relative contribution of genetic and environmental factors to variation in sleep-wake rhythm, measured by a continuous assessment of temperature-activity-position (TAP), which allows for diurnal sleep analysis. The sample comprised 53 pairs of female twins (28 MZ and 25 DZ), selected from the Murcia Twin Register. Mean age of participants was 52 (SD: 6.03). Zygosity was determined by DNA. We conducted separate univariate analyses to study the sources of variance of daytime and night-time sleep parameters. About 60% of the sample reported to take siesta at least once a week. Heritability of taking siesta and daytime sleep duration was 65 and 61% respectively. Other sleep parameters obtained by TAP showed heritability estimates between 36 and 69%, suggesting a relevant impact of genetic factors on sleep rhythm. This is the first study to investigate the relative contribution of genetic factors to siesta. By using TAP, we introduce a novel approach to the study of diurnal sleep characteristics.