Physical Activity and Urinary Sodium Excretion Circadian Rhythm: A Population-Based Cross-Sectional Pilot Study.

Background/Objectives: Blood pressure (BP) is characterized by a circadian rhythm (Circr) with lower nighttime values, called dipping. Non-dipping is associated with higher CVD risk. The Circr of urinary sodium excretion (NaCle), peaking during the day, is linked to BP patterns. Physical activity (PA) is known to improve BP control and enhance the dipping phenomenon, but its possible effect on NaCle remains unclarified. This study aimed to investigate the correlation between PA and the Circr of NaCle and to determine if the relationship is independent of age, sex, BP values, dipping pattern, and salt intake. Methods: A pilot cross-sectional analysis was conducted using data from the Ticino Epidemiological Stiffness Study, involving 953 participants in Switzerland. Data collection included standardized questionnaires, blood samples, 24 h urine collections, and ambulatory BP monitoring. Participants were categorized into sedentary, partially active, and active. The effect of PA, NaCl intake, and dipping on the day/night NaCle ratio was assessed with multivariable linear regressions. Results: Participants' median age was 49 years, with 78% having normal BP values and 47% exhibiting a dipping pattern; 51% were classified as sedentary and 22% as partially active. The median NaCl intake was 7.9 g/day. The youngest subjects had a higher hourly NaCle ratio compared to older subjects. Higher NaCl intake correlated with increased BP, a phenomenon more pronounced in men and younger subjects. The hourly day/night NaCle ratio positively correlates with dipping; however, PA did not show a significant correlation with the NaCle ratio. Conclusions: This study indicates that while the day/night NaCle ratio correlates with the dipping pattern, PA is unrelated to the circadian rhythm of renal sodium handling. The beneficial effects of PA on BP and cardiovascular health thus appear to be mediated through mechanisms other than NaCle. These are explorative findings only but relativize the need for further investigations on the topic.

Machine learning models reveal the critical role of nighttime systolic blood pressure in predicting functional outcome for acute ischemic stroke after endovascular thrombectomy.

Background: Blood pressure (BP) is a key factor for the clinical outcomes of acute ischemic stroke (AIS) receiving endovascular thrombectomy (EVT). However, the effect of the circadian pattern of BP on functional outcome is unclear. Methods: This multicenter, retrospective, observational study was conducted from 2016 to 2023 at three hospitals in China (ChiCTR2300077202). A total of 407 patients who underwent endovascular thrombectomy (EVT) and continuous 24-h BP monitoring were included. Two hundred forty-one cases from Beijing Hospital were allocated to the development group, while 166 cases from Peking University Shenzhen Hospital and Hainan General Hospital were used for external validation. Postoperative systolic BP (SBP) included daytime SBP, nighttime SBP, and 24-h average SBP. Least absolute shrinkage and selection operator (LASSO), support vector machine-recursive feature elimination (SVM-RFE), Boruta were used to screen for potential features associated with functional dependence defined as 3-month modified Rankin scale (mRS) score ≥ 3. Nine algorithms were applied for model construction and evaluated using area under the receiver operating characteristic curve (AUC), sensitivity, specificity, and accuracy. Results: Three hundred twenty-eight of 407 (80.6%) patients achieved successful recanalization and 182 patients (44.7%) were functional independent. NIHSS at onset, modified cerebral infarction thrombolysis grade, atrial fibrillation, coronary atherosclerotic heart disease, hypertension were identified as prognostic factors by the intersection of three algorithms to construct the baseline model. Compared to daytime SBP and 24-h SBP models, the AUC of baseline + nighttime SBP showed the highest AUC in all algorithms. The XGboost model performed the best among all the algorithms. ROC results showed an AUC of 0.841 in the development set and an AUC of 0.752 in the validation set for the baseline plus nighttime SBP model, with a brier score of 0.198. Conclusion: This study firstly explored the association between circadian BP patterns with functional outcome for AIS. Nighttime SBP may provide more clinical information regarding the prognosis of patients with AIS after EVT.

Circadian Urinary Excretion of Water, and Not Salt, Is Affected by the White Coat Effect.

Hypertension is an important morbidity factor. The prognostic consequences of the white-coat effect have been studied extensively. The repercussion on the circadian rhythm of urinary water and salt excretion in the same subgroup remain, conversely, among the open topics. Postulating an impaired diurnal sodium and volume excretion we decided to investigate both, in subjects with or without a white-coat effect, in the general population. A sample of 1023 subjects, has been considered. We collected 24-h urine samples, divided in day and night, and we measured the blood pressure with an Ambulatory Blood Pressure Monitoring (ABPM). ABPM values were then compared with physician collected in-office values to assign subjects to the group with or without the white-coat effect. Concerning the circadian pattern of urinary sodium excretion, we found no significant differences between the groups. There was instead in the white-coat effect group a higher night/day ratio of urinary water excretion. The white-coat effect, has been considered a potential hypertension precursor, and its consequent handling could be prospectively relevant in hypertension prevention. The absence of repercussions on the urinary circadian sodium excretion pattern and on the potentially related risk factors in subjects with a white coat effect is reassuring. The clinical significance of the impact on the night/day ratio of water excretion needs to be further investigated.

The birth hour of mammals: insights from intra-specific variation in wild blue monkeys.

While most mammals show birth hour peaks at times of the 24-h cycle when they are less active, there are exceptions to this general pattern. Such exceptions have been little explored, but may clarify evolutionary reasons for the diel timing of births. We investigated intraspecific variation in birth hour in wild blue monkeys Cercopithecus mitis stuhlmanni, a diurnal primate, to identify factors that differentiated daytime versus nighttime births. Behavioral and life history data from 14 groups over 14 years revealed that 4% of 484 births occurred during the day. Probability of daytime birth varied with mother's age, peaking at 15.7 years. Births whose annual timing deviated most from the population's peak birth months were 5 times more likely to occur during daytime than those that deviated less. There was no evidence that mother's rank or infant sex influenced birth hour, and mixed evidence that daytime births were more probable in larger groups. Survivorship did not differ significantly for infants born during the day versus night. Prime-aged mothers may be able to handle the consequences of an unusual birth hour more successfully than mothers with less experience or those weakened by age. Daytime birth may be more advantageous in the off-season because nights are colder at that time of year. These findings are consistent with hypotheses relating birth hour to the risk of losing social protection in group-living animals, but are not consistent with those emphasizing risk of conspecific harassment. Patterns of within-species variation can help in evaluating evolutionary hypotheses for non-random birth hour.

Triglyceride-to-glucose index to detect a non-dipping circadian pattern in newly diagnosed hypertensive patients.

Introduction: In this investigation, we aimed to explore the relationship between the triglyceride-glucose (TyG) index and the non-dipping blood pressure (BP) pattern in newly diagnosed hypertensive patients. Methods: In this retrospective study, 216 consecutive newly diagnosed hypertensive patients who had undergone 24-hour ambulatory blood pressure (ABPM) monitoring and had not received anti-hypertensive drugs were included. Non-dipping status was evaluated by a 24-h ABPM monitoring in all patients. We categorized the patients into two groups as; dippers (n=104 cases) and non-dippers (n=112 cases). The TyG index was derived from the fasting triglyceride and fasting glucose levels using the formula; ln[fasting triglyceride (mg/dL) × fasting glucose (mg/dL)/2]. Results: Non-dipper group had a higher TyG index than the dipper group. The TyG was an independent predictor of non-dipping BP in hypertensive individuals, according to multivariable analysis. The TyG index was negatively associated with a decrease in both systolic and diastolic BP during the nighttime. The ideal cutoff value of the TyG index in detecting non-dipping status was≥9.01 with 74.1% sensitivity and 71.2% specificity. A ROC comparison indicated that the area under the curve value of TyG index was superior to fasting triglyceride, fasting glucose, and homeostasis model assessment of IR (HOMA-IR) in detecting non-dipping BP. Conclusion: The TyG index was an independent predictor of non-dipping status in newly diagnosed hypertensive patients who had undergone 24-hour ABPM monitoring and had not received anti-hypertensive drugs. As a simple and easily obtained parameter, the TyG index can be used to detect such pattern among these patients.

Nocturnal blood pressure rather than night-to-day blood pressure ratio is related to arterial stiffening in untreated young and middle-aged adults with non-dipper hypertension.

Little is known about nocturnal blood pressure (BP) or night-to-day BP ratio, which is a more specific determinant of arterial stiffness in subjects with non-dipper hypertension? This study aims to investigate the correlation of nocturnal BP and brachial-ankle pulse wave velocity (ba PWV), an index of arterial stiffness in untreated young and middle-aged adults with non-dipper hypertension. A cross-sectional analysis of baseline parameters of the NARRAS trial was performed. Twenty-four hour ambulatory BP measurements, ba PWV and routine clinical data collection were performed in all patients. The relationship of 24-h ambulatory BP profiles, biochemical measures as well as demographic parameters and ba PWV were analyzed using Pearson's correlation and multiple stepwise regression analysis. A total of 77 patients (mean age 47.0 ± 11.7 years) with non-dipper hypertension were included. Age, height, weight and nocturnal systolic BP were related to ba PWV in Pearson's correlation analysis. In stepwise regression analysis, age (ß = 10.57, 95% confidence interval (CI): 6.099-15.042, p < 0.001) and weight (ß = -3.835, 95% CI: -7.658--0.013, p = 0.049) are related to ba PWV. Nocturnal systolic BP (ß = 8.662, 95% CI: 2.511-14.814, p = 0.006) was the independent predictors of ba PWV, even after night-to-day systolic BP ratio or 24-h ambulatory BP profile were taken into account. Nocturnal systolic BP rather than night-to-day systolic BP ratio appears to be a more specific determinant for arterial stiffness, as assessed by ba PWV in young and middle-aged adults with non-dipper hypertension. 24-h ambulatory BP measurements are essential for cardiovascular risk evaluation.

Extreme altitude changes between night and day during marathon flights of great snipes.

Several factors affect the flight altitude of migratory birds, such as topography, ambient temperature, wind conditions, air humidity, predation avoidance, landmark orientation, and avoiding over-heating from direct sunlight.1-6 Recent tracking of migratory birds over long distances has shown that migrants change flight altitude more commonly and dramatically than previously thought.4-8 The reasons behind these altitude changes are not well understood. In their seasonal migrations between Sweden and sub-Saharan Africa, great snipes Gallinago media make non-stop flights of 4,000-7,000 km, lasting 60-90 h.9,10 Activity and air pressure data from multisensor dataloggers showed that great snipes repeatedly changed altitudes around dawn and dusk, between average cruising heights about 2,000 m (above sea level) at night and around 4,000 m during daytime. Frequency and autocorrelation analyses corroborated a conspicuous diel cycle in flight altitude. Most birds regularly flew at 6,000 m and one bird reached 8,700 m, possibly the highest altitude ever recorded for an identified migrating bird. The diel altitude changes took place independently of climate zone, topography, and habitat overflown. Ambient temperature, wind condition, and humidity have no important diel variation at the high altitudes chosen by great snipes. Instead, improved view for orientation by landmarks, predator avoidance, and not least, seeking cold altitudes at day to counteract heating from direct sunlight are the most plausible explanations for the diel altitude cycle. Together with similar recent findings for a small songbird,6 the great snipes' altitudinal performance sheds new light on the complexity and challenges of migratory flights.

SGLT2 inhibitors and the autonomic nervous system in diabetes: A promising challenge to better understand multiple target improvement.

The puzzle of the multifaceted actions of sodium-glucose cotransporter type-2 inhibitors (SGLT2is) is still incomplete. For diabetologists (who are accustomed to dealing with the burden of cardiovascular autonomic neuropathy), the relationship between SGLT2is and the autonomic nervous system (ANS) represents one of the most intriguing aspects of the multiple effects of this family of drugs, especially given the poor availability of disease-modifying treatments for such complication. Therefore, the present review has considered both preclinical and clinical studies of this topic with autonomic perspectives by exploring the pathophysiological background of the interactions between the ANS and SGLT2, including sympathetic control of kidney function and the role of renal afferent nerves, and also by providing insights into the effects of SGLT2is on 24-h blood pressure (BP) and heart rate variability (HRV), with particular attention focused on the EMBODY trial. Indeed, despite the difficulties of exploring such a complex network comprising the kidney, heart and the ANS while targeting a single outcome-circadian BP and HRV-the available studies do offer evidence that SGLT2i actions are in part mediated by neural circuitry and the ANS. Thus, at this time, the worthwhile incidental result of these (and future) studies has been to highlight the role of autonomic innervation in the pathophysiology of kidney and heart disease.

Renal Functional Reserve Is Related to the Nondipping Phenotype and to the Exercise Heart Rate Response in Patients with Essential Hypertension and Preserved Renal Function.

BACKGROUND: Renal functional reserve (RFR), defined as the difference between stress and resting glomerular filtration rate (GFR), may constitute a diagnostic tool to identify patients at higher risk of developing acute kidney injury or chronic kidney disease. Blunted RFR has been demonstrated in early stages of hypertension and has been attributed to impaired vascular reactivity due to an overactive sympathetic nervous system (SNS). OBJECTIVE: The purpose of this study was to investigate whether RFR correlates with other phenotypes expressing overactivity of the SNS in patients with essential hypertension and preserved renal function. METHODS: Thirty-six patients with untreated essential hypertension and a GFR >60 mL/min/1.73 m2 were enrolled. The following parameters were measured: RFR, 24-h ambulatory blood pressure (BP) profile, a treadmill stress test, and an echocardiographic examination. Urine and venous samples were obtained at specific time points for the determination of clinical parameters, and both resting and stress GFR were calculated by using endogenous creatinine clearance for the measurement of RFR after an acute oral protein load (1 g/kg). RESULTS: Twenty-one patients had a RFR <30 mL/min/1.73 m2 and 15 had a RFR above this cutoff. A nondipping pattern of 24-h BP was significantly more frequent in patients with low RFR (57.1 vs. 25.0%, p < 0.05 for systolic BP and 52.3 vs. 10.0%, p < 0.02 for diastolic BP). Moreover, patients with lower RFR values showed a blunted heart rate (HR) response to exercise during treadmill test (r = 0.439, p < 0.05). None of the echocardiographic parameters differed between the two groups of patients. CONCLUSIONS: In hypertensive patients with preserved GFR, reduced RFR is related to nondipping BP phenotype as well as to attenuated exercise HR response. Overactivity of the SNS may be a common pathway. Since loss of RFR may represent a risk factor for acute or chronic kidney injury, hypertensive patients with blunted RFR might need a more careful renal follow-up.

Comparison of clinical outcomes in STEMI patients treated with primary PCI according to day-time of medical attention and its relationship with circadian pattern.

OBJECTIVE: Relationship between STEMI time of presentation, its circadian pattern and cardiovascular outcomes is unclear. Our objective is to analyze clinical outcomes of STEMI according to time of presentation and circadian pattern. METHODS: We analyzed data from patients treated within the regional STEMI Network from January 2010 to December 2015. On-hour group included patients treated between 8:00 h and 19:59 h on weekdays, the rest were catalogued as off-hour group. The primary endpoint was 1-year all-cause mortality. Secondary endpoints were 30-day all-cause mortality and in-hospital complications. RESULTS: A total of 8608 patients were included, 44.1% in the on-hour group and 55.9% in the off-hour group. We observed a shorter patient delay and longer system delay in the off-hour group compared to on-hour group with no difference in total ischemic time. At 30-day and 1-year follow-up there were no differences in adjusted all-cause mortality between groups [OR 0.91 (CI95%: 0.73-1.12; p = 0.35) and OR 0.99 (CI95%: 0.83-1.17; p = 0.87), respectively]. A circadian pattern was observed between 9:00 am and 12:30 pm, with no differences in 30-day and 1-year mortality between patients included in this time interval [OR 1.02 (IC95%: 0.81-1.30; p = 0.85) and OR 1.12 (IC95%: 0.92-1.36; p = 0.25) respectively]. CONCLUSIONS: Off-hour STEMI presentation was associated with a shorter patient delay and longer system delay without an increase in total ischemic time. The off-hour presentation was not related to an increase in 1-year all-cause mortality when compared to on-hour. A circadian pattern was found, without differences in 30-day and 1-year mortality.

Dietary supplementation of menthol-rich bioactive lipid compounds alters circadian eating behaviour of sheep.

BACKGROUND: Plant bioactive lipid compounds (PBLC), commonly known as essential oils, are increasingly evaluated as feed additives in ruminants due to beneficial effects on animal performance and health; however, there is no study evaluating circadian eating behaviour in ruminants. Altered eating behaviour may be implicated in changes of feed intake in ruminants. Therefore, the present study investigated the influence of menthol-rich PBLC on circadian eating behaviour in 24 growing sheep that were equally divided into three treatments, control (without PBLC), a lower dose (80 mg/d) or a higher dose (160 mg/d) of PBLC. Daily doses of PBLC were supplied with 600 g/d of concentrates fed in three equal portions at 07:00, 11:00 and 15:00 h for 4 weeks, whereas, meadow hay was fed ad libitum. RESULTS: The eating behaviour recorded by an automatic transponder-operated feeding system revealed that daily eating time and feeder visits increased with increasing doses of PBLC. The circadian distribution of eating time and feeder visits (with 1-h resolution) was influenced by the treatment. Eating time during concentrate-offering hours and between concentrate-offering hours increased or tended to increase linearly with greater concentrations of PBLC. Feeder visits did not change significantly during concentrate-offering hours, but were greater in the PBLC groups compared with the control between concentrate-feeding hours. Average length of the longest meals (5th percentile) decreased due to PBLC feeding. Daily feed intake was greater in the PBLC groups than the control. CONCLUSIONS: Menthol-rich PBLC in the applied dose range stimulate circadian eating behaviour, which cannot only be attributed to their presence during concentrate feeding hours, but persist during post-concentrate feeding hours.

Association between Growth Differentiation Factor 15 and Non-Dipping Circadian Pattern in Patients with Newly Diagnosed Essential Hypertension.

OBJECTIVE: Non-dipper hypertension (HT) confers greater risk compared with dipper HT. Growth differentiation factor 15 (GDF-15) recently emerged as a novel and independent marker of cardiovascular disease, both in diagnostic and prognostic scopes. Our aim was to evaluate the relationship of circadian blood pressure (BP) pattern with serum GDF-15 level in newly diagnosed HT patients without left ventricular hypertrophy. SUBJECTS AND METHODS: Newly diagnosed non-dipper (n = 66) and dipper (n = 60) HT patients were selected according to 24-h ambulatory BP monitoring (ABPM). The controls comprised healthy normotensive subjects (n = 31). Data was collected through physical examination, laboratory analysis, ABPM, and echocardiography. GDF-15 was measured using ELISA. RESULTS: Greater GDF-15 level was found in the non-dippers compared with the dippers and the controls (557.53 ± 91.7, 513.79 ± 62.86, and 494.44 ± 79.30 ng/L, respectively, p < 0.001). In bivariate linear correlation analysis, GDF-15 correlated positively with glomerular filtration rate (r = 0.180, p =0.030), total cholesterol (r = 0.170, p = 0.038), septal E/E' ratio (r = 0.344, p = 0.001), lateral E/E' ratio (r = 0.366, p < 0.001), nighttime systolic BP (r = 0.166, p = 0.046), and nighttime diastolic BP (r = 0.188, p = 0.024); however, it correlated negatively with septal and lateral E' velocities (r = 0.268, p = 0.005 and r = 0.236, p = 0.013, respectively). Furthermore, GDF-15 level and nighttime diastolic BP remained independently associated with non-dipper HT. In ROC analysis, optimal cutoff value for GDF-15 was 524.6 ng/L with 56.7% sensitivity and 72.4% specificity (AUC: 0.676, 95% CI: 0.580-0.772, p < 0.05). CONCLUSION: Our results showed GDF-15 upregulation in the non-dipper HT group. GDF-15 and nighttime diastolic BP were independently associated with the non-dipping pattern. This study may suggest possible utilization of GDF-15 in the prediction of non-dipper HT.

Circadian, weekly, seasonal, and temperature-dependent patterns of syncope aetiology in patients at increased risk of cardiac syncope.

AIMS: It is unknown whether cardiac syncope, and possibly also other syncope aetiologies exhibit circadian, weekly, seasonal, and temperature-dependent patterns. METHODS AND RESULTS: We prospectively recorded the exact time, date, and outside temperature of syncope of patients >40 years old presenting with syncope to the emergency department in a diagnostic multicentre study. Two independent cardiologists/emergency physicians adjudicated the final diagnosis based on all information becoming available during clinical work-up including 1-year follow-up. Among 1230 patients, the adjudicated aetiology was cardiac in 14.6%, reflex in 39.2%, orthostatic in 25.7%, other non-cardiac in 9.7%, and unknown in 10.8% of patients. All syncope aetiologies occurred much more frequently during the day when compared with the night (P < 0.01). While reflex and orthostatic syncope showed a broad peak of prevalence with 80.9% of these events occurring between 4 am and 4 pm, cardiac syncope showed a narrow peak of prevalence with 70.1% of all events occurring between 8 am and 2 pm. A weekly pattern was present for most syncope aetiologies, with events occurring mainly from Monday to Friday (P < 0.01). Reflex syncope displayed a seasonal rhythm and was more common in winter (P < 0.01), while cardiac syncope stayed constant over the year. Syncope occurred most often when the outside temperature was coldest. Overall the patterns observed for cardiac syncope were similar to the patterns observed for its differential diagnosis. CONCLUSION: Syncope aetiologies in patients >40 years old display circadian, weekly, seasonal, and temperature-dependent patterns. Unfortunately, these patterns do not allow to reliably differentiate cardiac syncope from other aetiologies.

Diurnal variation in suicide timing by age and gender: Evidence from Japan across 41 years.

BACKGROUND: Previous research on hourly diurnal variation in suicide frequency has often suffered from geographical and time-span limitations in the data. We studied diurnal and daily variations of suicide by analyzing a large dataset based on the national death registry in Japan between 1974 and 2014. METHODS: The diurnal and daily patterns of 873,268 suicide deaths over 41 years were examined by sex and age group through Poisson regression and visual inspection. We also investigated whether these patterns are related to Japan's economic conditions. RESULTS: Suicide by middle-aged males was most frequent in the early morning especially on Mondays after the end of Japan's high growth period. We also observed large midnight peaks in suicides among young and middle-aged males. The proportion of early morning suicide deaths by young and middle-aged males increased as the country's unemployment rose. Females and elderly males were more likely to die by suicide during the day than at night. LIMITATION: Our study examined time of death, not time of suicide attempt. It is possible that there is a discrepancy between the two. CONCLUSIONS: Different subpopulations die by suicide at different times of the day and days of the week. Time patterns of suicide varied considerably over time, suggesting that they cannot be explained by biological circadian rhythm alone. Our findings suggest that the patterns are partly explained by economic conditions. Future suicide prevention efforts should consider the time patterns of suicide unique to each subpopulation, especially when economic growth is depressed.

Latent Variable Poisson Models for Assessing the Regularity of Circadian Patterns over Time.

Many researchers in biology and medicine have focused on trying to understand biological rhythms and their potential impact on disease. A common biological rhythm is circadian, where the cycle repeats itself every 24 hours. However, a disturbance of the circadian pattern may be indicative of future disease. In this article, we develop new statistical methodology for assessing the degree of disturbance or irregularity in a circadian pattern for count sequences that are observed over time in a population of individuals. We develop a latent variable Poisson modeling approach with both circadian and stochastic short-term trend (autoregressive latent process) components that allow for individual variation in the degree of each component. A parameterization is proposed for modeling covariate dependence on the proportion of these two model components across individuals. In addition, we incorporate covariate dependence in the overall mean, the magnitude of the trend, and the phase-shift of the circadian pattern. Innovative Markov chain Monte Carlo sampling is used to carry out Bayesian posterior computation. Several variations of the proposed models are considered and compared using the deviance information criterion. We illustrate this methodology with longitudinal physical activity count data measured in a longitudinal cohort of adolescents.

Disrupted day-night pattern of cardiovascular death in obstructive sleep apnea.

BACKGROUND: Obstructive sleep apnea (OSA) patients who suffer sudden cardiac death die predominantly during the night. We aimed to investigate whether all cardiovascular-related deaths display the same night-time peak as sudden cardiac death. METHODS: Data from a large cohort of adults who underwent full-night polysomnography between 1985 and 2015 in a university-affiliated sleep clinic were analyzed. Time and cause of death of these patients and of persons from the general population were identified in death certificates from the State Health Secretariat. The day-night pattern of cardiovascular death was compared among groups of non-OSA, OSA (apnea-hypopnea index, AHI ≥5), CPAP users, and persons from the general population. RESULTS: Among 619 certificates, 160 cardiovascular-related deaths were identified. The time of death of the 142 persons with OSA was uniformly distributed over 24 h, with neither an identifiable peak nor a circadian pattern (Rayleigh test; P = 0.8); the same flat distribution was seen in those with purported CPAP use (n = 49). Non-OSA individuals presented a morning peak and a night nadir of deaths, clearer when analyzed in eight-hour intervals. The same pattern was observed in 92 836 certificates from the State general population, with cardiovascular deaths showing the expected morning peak, night nadir, and a significant circadian pattern (Rayleigh test; P < 0.001). CONCLUSIONS: In OSA patients, the distribution of cardiovascular-related deaths throughout the 24-h period is virtually flat, in contrast with the described nighttime peak of sudden cardiac death. OSA-related phenomena during nighttime might be blunting the mechanisms, arrhythmic or not, behind the morning peak of cardiovascular-related deaths.

[Ambulatory blood pressure monitoring is a useful tool for all patients]. / La monitorización ambulatoria de la presión arterial es un instrumento aconsejable para todos los pacientes.

Clinical blood pressure measurement (BP) is an occasional and imperfect way of estimating this biological variable. Ambulatory blood pressure monitoring (ABPM) is by far the best clinical tool for measuring an individual's blood pressure. Mean values over 24h, through the daytime and at night all make it more possible to predict organic damage and the future development of the disorder. ABPM enables the detection of white-coat hypertension and masked hypertension in both the diagnosis and follow-up of treated patients. Although some of the advantages of ABPM can be reproduced by more automated measurement without the presence of an observer in the clinic or self-measurement at home, there are some other elements of great interest that are unique to ABPM, such as seeing what happens to a patient's BP at night, the night time dipping pattern and short-term variability, all of which relate equally to the patient's prognosis. There is no scientific or clinical justification for denying these advantages, and ABPM should form part of the evaluation and follow-up of practically all hypertensive patients. Rather than continuing unhelpful discussions as to its availability and acceptability, we should concentrate our efforts on ensuring its universal availability and clearly explaining its advantages to both doctors and patients.

Validating faecal glucocorticoid metabolite analysis in the Virunga mountain gorilla using a natural biological stressor.

The continued degradation of primate habitat worldwide is forcing many primate populations into small protected forest islands surrounded by high-density human populations. One well-studied example is the critically endangered mountain gorilla (Gorilla beringei beringei). Decades of monitoring and research on Rwanda's mountain gorillas offer a unique opportunity to use non-invasive endocrine analysis to address pressing questions about the conservation of this endangered population. The aims of our study were as follows: (i) to validate field and laboratory methods for assessing stress through faecal glucocorticoid metabolite (FGM) analysis using inter-social unit interactions as a natural stressor; (ii) to determine the excretion lag times between interactions and detectable stress response in faeces; and (iii) to determine whether there are circadian patterns of FGM excretion. We collected ~6000 faecal samples from 127 known gorillas in 10 habituated groups, monitored by the Dian Fossey Gorilla Fund's Karisoke Research Center over 21 months in 2011 and 2012. Extracted FGMs were measured using a cortisol enzyme immunoassay (R4866; C. J. Munro). Results revealed cause-effect relationships between inter-unit interactions and increased FGMs (relative to individual pre-event samples) between 20 and 140 h after interactions, with the peak most often occurring on day 3. There was no evidence of circadian patterns in FGM concentrations, as previously shown in many species with long gut passage times. However, baseline FGM concentrations were lower in adult males than in adult females, and variation was associated with the collection month, indicating possible seasonal variation. This study provides a biologically validated, field-friendly faecal hormone metabolite extraction and laboratory enzyme immunoassay analysis method for non-invasive monitoring of adrenocortical activity in Virunga mountain gorillas. The methods are useful for future evaluation of a variety of environmental and human-induced potential stressors in this critically endangered population.

Breast-Milk Cortisol and Cortisone Concentrations Follow the Diurnal Rhythm of Maternal Hypothalamus-Pituitary-Adrenal Axis Activity.

BACKGROUND: Very preterm infants often receive donor milk from mothers who deliver at term, but its composition differs from that of their own mother's milk. Because breast-milk glucocorticoids can support developing neonates, we explored concentration variability within and between mothers. OBJECTIVE: We hypothesized that breast-milk glucocorticoid concentrations would be higher after very preterm delivery [gestational age (GA) <32 wk; study 1] and would follow the diurnal rhythm of maternal adrenocortical activity (study 2). METHODS: Study 1 assessed differences in milk cortisol, cortisone, and the cortisone-to-(cortisol+cortisone) ratio of mothers who delivered at (median) GA: 28.6 wk or at term weekly during the first month postpartum. Study 2 assessed variations in milk cortisol, cortisone, and the cortisone-to-(cortisol+cortisone) ratio over 24 h, and tested Pearson correlations between milk and salivary concentrations in mothers who delivered at term (median GA: 38.9 wk) during week 4 postpartum. In these studies, foremilk glucocorticoids were measured by liquid chromatography-tandem mass spectrometry. Associations of milk cortisol, milk cortisone, and the milk cortisone-to-(cortisol+cortisone) ratio with prematurity (study 1) or collection time (study 2) were studied with longitudinal data analyses. RESULTS: In study 1, giving birth to a very preterm infant was associated with reductions in milk cortisol and cortisone concentrations of 50% (ß: 0.50; 95% CI: 0.26, 0.99; P = 0.05) and 53% (ß: 0.53; 95% CI: 0.30, 0.93; P = 0.03), respectively, when adjusted for collection time. In study 2, concentrations of milk cortisol and cortisone were associated with collection time (both P < 0.01), peaking at ∼0700. Milk and salivary concentrations of cortisol (r = 0.92, P < 0.01) and cortisone (r = 0.93, P < 0.01) as well as the cortisone-to-(cortisol+cortisone) ratio (r = 0.64, P < 0.01) were correlated with one another. CONCLUSIONS: Breast-milk glucocorticoid concentrations follow the diurnal rhythm of maternal hypothalamus-pituitary-adrenal axis activity and are lower in mothers who deliver very preterm.

Why do captive pied tamarins give birth during the day?

Diurnal primates typically give birth at night, when it is presumed that they are safer at a very vulnerable time, and this is reflected in an overwhelmingly nocturnal pattern of delivery in most species of Callitrichidae. However, over half (51.1%) of 88 births to pied tamarins (Saguinus bicolor) at Durrell Wildlife Park occurred during the day (0800-1700), almost always in the afternoon. Nearly three quarters of breeding females (17/23) had at least one diurnal birth, including females from all generations in captivity from wild-caught to fifth captive-born generation, and from all six matrilines represented at Durrell. The proportion of diurnal births has remained relatively stable over time despite management changes. We used generalized linear mixed modeling to investigate several factors that we hypothesized could affect time of birth: maternal experience, season, female rearing history, and whether or not the group was on public display. We fitted all possible models to the data, but none explained more than 7.5% of the variation. Daytime delivery had few statistically significant detrimental effects, although infant survival was somewhat lower and parental rejection increased in diurnal births. Pied tamarins do not seem to fit any of the hypotheses previously put forward to explain exceptions to the typical primate circadian pattern of delivery. Zoo Biol. 35:487-494, 2016. © 2016 Wiley Periodicals, Inc.