Fetal motor activity and maternal cortisol

The contemporaneous association between maternal salivary cortisol and fetal motor activity was examined at 32 and 36 weeks gestation. Higher maternal cortisol was positively associated with the amplitude of fetal motor activity at 32 weeks, r(48) = .39, p < .01, and 36 weeks, r(77) = .27, p < .05, and the amount of time fetuses spent moving at 32 weeks during the 50 min observation period, r(48) = 33, p < .05. Observation of periods of unusually intense fetal motor activity were more common in fetuses of women with higher cortisol, Mann–Whitney U = 58.5. There were no sex differences in fetal motor activity, but the associations between maternal cortisol and fetal motor amplitude and overall movement were significantly stronger for male than female fetuses. © 2009 Wiley Periodicals, Inc. Dev Psychobiol 51: 505–512, 2009     

Diurnal rhythms in plasma cortisol, insulin, glucose, lactate and urea in pigs fed identical meals at 12-hourly intervals

Diurnal rhythms in plasma cortisol, insulin, glucose, lactate and urea concentrations were investigated in eight catheterized pigs of approximately 35 kg BW. Pigs were fed isoenergetic/isoproteinic diets at a restricted level (2.5 x maintenance requirement for energy) in two daily rations (06:00 and 18:00 hours) in order to obtain equal intervals between feed intake. Preprandial plasma cortisol concentration was 22+/-3 ng/mL in the morning and 14+/-2 ng/mL in the evening (p<0.025), whereas the concentrations of insulin, glucose, lactate, and urea were similar. In the postprandial period in the morning (06:00-09:00 hours) plasma cortisol, insulin and lactate concentrations (expressed as the total area under the curve) were greater (p<0.001) compared to the evening (18:00-21:00 hours) by 100%, 42%, and 24%, respectively, while postprandial plasma glucose and urea concentrations were not affected by time of the meal. When postprandial plasma concentrations were expressed as a response over preprandial concentrations (decremental or incremental area under the curve), the diurnal rhythm was not observed for cortisol and glucose, persisted for insulin and lactate, and appeared for urea with a smaller postprandial urea response (p<0.05) in the morning compared to the evening. We conclude that the diurnal rhythm in plasma cortisol is independent of feeding whereas the diurnal rhythms in plasma insulin, lactate and urea are unveiled by the morning/evening meals in pigs. At equal 12-h intervals between meals, the postprandial responses of lactate and urea show diurnal variations, each in a specific manner, which suggest decreased postprandial efficiency of carbohydrate metabolism and increased postprandial efficiency of protein metabolism in the morning compared to the evening.     

Cortisol circadian rhythms and stress responses in infants at risk of allergic disease

BACKGROUND: The cortisol circadian rhythm and response to stressful stimuli are altered in children and adults with allergic disease, including asthma. It is not known whether these alterations precede or follow the onset of allergic disease. OBJECTIVE: We sought to evaluate the cortisol circadian rhythm and stress response among infants at risk for the development of allergic disease. METHODS: Infants with and without risk factors for allergic disease were evaluated at age 6 months. Saliva was obtained at 8 am, 2 pm, and 8 pm at home (n = 68) by parents when their infants were comfortable and in the clinic (n = 88) before and after their physical examination and vaccinations. Information regarding parental allergy and exposure to other children at home or in child care were obtained by questionnaire. RESULTS: In multivariate analysis the circadian rhythm of cortisol was flattened because of the lack of the expected morning surge of cortisol, resulting in decreased diurnal variation of cortisol in infants of mothers with allergy (P = .035) or asthma (P = .002) or an asthmatic father (P = .022). The cortisol stress response was greater in infants of mothers with allergy (P = .045) or asthma (P = .039), those with fewer siblings (P = .066), and those not entering day care early in life (P = .017). CONCLUSIONS: These alterations in both basal and stress levels of endogenous cortisol among infants predisposed to allergic disease might affect the development of allergic immune responses early in life through interactions with inflammatory mediators.     

Psychoneuroendocrinoimmunology-based meditation (PNEIMED) training reduces salivary cortisol under basal and stressful conditions in healthy university students: Results of a randomized controlled study

BackgroundMeditation represents an effective and safe practice to lower distress and promote well-being. PsychoNeuroEndocrinoImmunology-based Meditation (PNEIMED) is a validated method that can reduce stress-related symptoms and salivary cortisol secretion. To date, few randomised controlled trials (RCTs) have assessed cortisol levels through salivary samples, collected both in the morning phase and during acute mental stress elicitation, in healthy young subjects following brief meditation training.AimThe present study aims to investigate, in healthy young undergraduate students, the effects of a brief PNEIMED training course on HPA axis by measuring salivary cortisol levels.MethodsForty students attending the Faculty of Psychology, without comorbidities and previous experience of meditation, were enrolled in the study. Twenty subjects were randomly assigned to 30 h of PNEIMED training (intervention group, IG), and twenty subjects were randomly assigned to 30 h of academic lessons (control group, CG). Salivary cortisol measures included basal morning (t0 = baseline time, collected 30 min after waking) and under stress-eliciting task values. Cortisol measurement under the stress-eliciting task was provided through the Subtraction Stress Task (SST) at scheduled time intervals (t1 = 5 min pre-SST, t2 = 10 min post-SST, t3 = 30 min = post-SST). Salivary cortisol was measured among all subjects (IG + CG) at the beginning (pre-test) and at the end (post-test, four days later) of the study.ResultsANOVA between-group analysis of basal diurnal salivary cortisol showed a significant hormone deflection in the IG at the end of the PNEIMED course (post-test) when compared to the CG (IG post-test 5.64 ± 4.2 vs CG post-test 9.44 ± 4.9; F_1,38 = 6.838; p = 0.013). RM-ANOVA within-group analysis for the IG also showed that time and condition effects were statistically significant, with Ftime = 5.438; p = 0.002 and Fcondition = 10.478; p = 0.004, respectively. The IG group presented a significant reduction in basal morning cortisol at the end of the PNEIMED course (post-test) compared to the salivary concentration at baseline (pre-test) (IG pre-test 9.42 ± 6.0 vs IG post-test 5.64 ± 4.2; F_1,38 8,354; p = 0.009). RM-ANOVA for the control group showed only the main effect of time (F_1,38 = 40.348; p < 0.001). Regarding cortisol measures under the SST-stress eliciting task, ANOVA between-groups analysis showed higher cortisol levels in the IG than in the CG before the PNEIMED course, with significant differences between groups at time t2 and time t3. After the PNEIMED course, the cortisol levels in the IG had decreased, although the differences between groups were not significant. Interestingly, ANOVA within-groups analysis showed that in the IG, the cortisol levels post-test (after the PNEIMED course) were lower than at pre-test (before the PNEIMED course), showing a significant difference of cortisol salivary concentration between conditions at t3 (F = 5.326; p = 0.032). In the control group, the post-hoc analyses for pairwise comparisons between conditions (pre-test vs post-test) did not show significant differences.ConclusionAlthough the low number of subjects enrolled in the study does not allow for definitive conclusions to be drawn, the present findings confirmed the capability of the PNEIMED method to lower stress hormone secretion both at baseline and under acute mental stimulation in a group of young naïve practitioners and make a contribution to the existing literature by increasing the number of published RCTs about the topic.     

Salivary cortisol in pregnant women suffering from blood and injection phobia

Stress and/or anxiety during pregnancy affect maternal and fetal well-being and can cause premature delivery and postnatal pathology in the child. Women suffering from phobias related to blood and injections are prone to high levels of stress, including anxiety and sometimes panic attacks, during pregnancy. Cortisol is amongst the mediators through which the neurohormonal expressions of maternal psychological factors may be transduced to the fetus. The aim of this study was to investigate whether pregnant women suffering from blood and injection phobia have raised cortisol levels or are characterized by unusual diurnal salivary cortisol profiles compared with healthy controls. The sample consisted of 110 pregnant women with blood and injection phobia and 110 pregnant healthy controls. Both groups provided morning and evening saliva samples in weeks 25 and 36 for the assay of cortisol. In gestational week 25, when blood was drawn for the mandatory blood testing, extra blood was taken to analyze corticotrophin-releasing factor, adrenocorticotropic hormone, and cortisol in serum. The diurnal decline in salivary cortisol as well as increased cortisol levels were observed during pregnancy. Pregnant women suffering from blood and injection phobia had a higher output of cortisol compared with women without the phobia (F = 6.25, df = 1, p = 0.014), but no marked difference in the diurnal cortisol rhythm was found between groups. Our findings indicate that untreated blood and injection phobia during pregnancy increases cortisol concentrations. Blood and injection phobia is treatable, and cognitive behavioral therapy can be used. Women with blood and injection phobia during pregnancy therefore need to be recognized and offered treatment without delay in early pregnancy.     

Diurnal saliva cortisol levels and relations to psychosocial factors in a population sample of middle-aged swedish men and women

Whereas psychosocial risk factors increase the risk for disease, psychosocial resources reduce this risk. To examine a possible pathway for these effects, the relations between saliva cortisol levels and psychosocial factors were studied in a random sample of 257 men and women aged 30 to 64 years. Saliva samples were collected at home on waking, 30 min after waking, and in the evening. A flatter diurnal rhythm of cortisol, that is, lower deviations between awakening and evening cortisol levels, was related to high levels of psychosocial risk factors (cynicism, depression, and vital exhaustion), whereas a steeper diurnal rhythm was related to psychosocial resources (social support and coping), general health, and well-being (all p < .05). Our results support earlier suggestions that the capacity of the hypothalamic-pituitary-adrenal-axis to dynamically respond to stress is 1 pathway for observed effects of psychosocial factors regarding risk for disease development.     

Salivary cortisol and DHEA levels in the Korean population: age-related differences, diurnal rhythm, and correlations with serum levels

PURPOSE: The primary objective of this study was to examine the changes of basal cortisol and DHEA levels present in saliva and serum with age, and to determine the correlation coefficients of steroid concentrations between saliva and serum. The secondary objective was to obtain a standard diurnal rhythm of salivary cortisol and DHEA in the Korean population. MATERIALS AND METHODS: For the first objective, saliva and blood samples were collected between 10 and 11 AM from 359 volunteers ranging from 21 to 69 years old (167 men and 192 women). For the second objective, four saliva samples (post-awakening, 11 AM, 4 PM, and bedtime) were collected throughout a day from 78 volunteers (42 women and 36 men) ranging from 20 to 40 years old. Cortisol and DHEA levels were measured using a radioimmunoassay (RIA). RESULTS: The morning cortisol and DHEA levels, and the age- related steroid decline patterns were similar in both genders. Serum cortisol levels significantly decreased around forty years of age (p < 0.001, when compared with people in their 20s), and linear regression analysis with age showed a significant declining pattern (slope=-2.29, t=-4.297, p < 0.001). However, salivary cortisol levels did not change significantly with age, but showed a tendency towards decline (slope=-0.0078, t=-0.389, p=0.697). The relative cortisol ratio of serum to saliva was 3.4-4.5% and the ratio increased with age (slope=0.051, t=3.61, p < 0.001). DHEA levels also declined with age in saliva (slope=-0.007, t=-3.76, p < 0.001) and serum (slope=-0.197 t=-4.88, p < 0.001). In particular, DHEA levels in saliva and serum did not start to significantly decrease until ages in the 40s, but then decreased significantly further at ages in the 50s (p < 0.001, when compared with the 40s age group) and 60s (p < 0.001, when compared with the 50 age group). The relative DHEA ratio of serum to saliva was similar throughout the ages examined (slop=0.0016, t=0.344, p=0.73). On the other hand, cortisol and DHEA levels in saliva reflected well those in serum (r=0.59 and 0.86, respectively, p < 0.001). The highest salivary cortisol levels appeared just after awakening (about two fold higher than the 11 AM level), decreased throughout the day, and reached the lowest levels at bedtime (p < 0.001, when compared with PM cortisol levels). The highest salivary DHEA levels also appeared after awakening (about 1.5 fold higher than the 11 AM level) and decreased by 11 AM (p < 0.001). DHEA levels did not decrease further until bedtime (p=0.11, when compared with PM DHEA levels). CONCLUSION: This study showed that cortisol and DHEA levels change with age and that the negative slope of DHEA was steeper than that of cortisol in saliva and serum. As the cortisol and DHEA levels in saliva reflected those in serum, the measurement of steroid levels in saliva provide a useful and practical tool to evaluate adrenal functions, which are essential for clinical diagnosis.     

Intervention effects on foster parent stress: associations with child cortisol levels

Foster children exhibit high rates of atypical neuroendocrine functioning compared to children in the general population. In particular, alterations in the daytime diurnal activity of the hypothalamic-pituitary-adrenal (HPA) axis have been observed in foster children, often characterized by blunted salivary cortisol levels (i.e., low morning levels that remain low throughout the day). There is emerging evidence that therapeutic interventions for foster children can affect this pattern of HPA axis activity, but the specific intervention components responsible for change have not been fully explicated. Within a randomized trial to evaluate a therapeutic intervention for foster preschoolers (n = 57 intervention condition; n = 60 comparison condition; n = 60 community comparison condition), the present study examined whether diurnal cortisol activity was associated with caregiver self-reported stress in response to child problem behavior. Results showed immediate reductions in caregiver stress that were sustained through 12 months postbaseline in the intervention condition. In contrast, caregivers in the regular foster care condition showed higher rates of stress across time and increased stress sensitivity to child problem behaviors. In addition, among caregivers in regular foster care, higher self-reported stress was associated with lower morning cortisol levels and more blunted diurnal cortisol activity. These results provide evidence that interventions can simultaneously impact caregiver stress and buffer children from the negative impacts of caregiver stress on HPA axis regulation.     

Diurnal rhythm of mitotic activity in cells of the interalveolar septa of the rat lung and its variation with age

The diurnal rhythm of mitotic activity in cells of the interalveolar septa of the lungs of 20-day rat fetuses corresponds to the rhythm in the adult. In rats aged 1, 3, and 10 days the curve of diurnal fluctuations of mitotic activity has a maximum in the evening and a minimum in the morning. After the 17th day of postnatal development the definitive diurnal rhythm with a maximum of the number of mitoses in the morning and the minimum in the evening is established in the lung tissue. The mean diurnal mitotic activity, although very high in the fetus, falls sharply immediately after birth. It rises again on the third day, but falls on the seventh day and later.Department of General Biology, N. I. Pirogov Second Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR A. P. Avtsyn.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 2, pp. 226–228, February, 1976.     

Patterns of salivary cortisol levels can manifest work stress in emergency care providers

To develop objective assessments of work fatigue, we investigated the patterns of changes in salivary cortisol levels in emergency care providers working extended work shifts. Fourteen subjects, comprising seven physicians and seven physician assistants, provided unstimulated saliva samples at regular intervals over the course of a 24-h work shift and over their subsequent free day. There was a significant time effect, with early morning cortisol levels being significantly attenuated following the work shift. Native diurnal variations varied by gender, with the female subjects manifesting greater cortisol levels. Physicians also had higher cortisol profiles even though their wake–rest cycles were similar to those of the physician assistants. Our results suggest that temporal changes, as well as diurnal similarities, in the salivary cortisol patterns can reflect work-related stress and recovery. In particular, early morning cortisol levels may manifest individual reactivity to work stressors as well as sleep deprivation.     

The influence of regulatory T cells and diurnal hormone rhythms on T helper cell activity

Symptoms of diseases such as rheumatoid arthritis, which is T helper 1 (Th1) dependent, and asthma, which is T helper 2 (Th2) dependent, are influenced by diurnal rhythms and natural regulatory T cells (nTreg). However, the mechanisms responsible for the diurnal rhythm of disease activity have not been identified and it is unclear whether nTreg activity is diurnal rhythm‐dependent. We therefore investigated whether a 24‐hr diurnal cycle affected the ability of various helper T‐cell populations to generate immunomodulatory and pro‐inflammatory cytokines, as well as its suppression by nTreg cells. Using a within‐subject crossover design, sleep versus continuous wakefulness was compared over a 24‐hr period in healthy young volunteers under defined environmental conditions. Venous blood was drawn periodically every 5 hr and the function of T cells was explored in vitro. We demonstrated that interleukin (IL)‐2, interferon‐γ (IFN‐γ), tumour necrosis factor‐α (TNF‐α) and IL‐10 secretion by naïve CD4⁺ T cells follows a diurnal rhythm. Furthermore, multiple regression analysis, as well as subsequent in vitro experiments, suggested that serum levels of cortisol and prolactin are part of the underlying mechanism. Additionally, we observed that nTreg suppressed the secretion of IFN‐γ, IL‐2 and TNF‐α, but not the secretion of IL‐4, IL‐6, IL‐10 and IL‐17A. However, the abrogation of IL‐2 release was reversed upon inhibiting CD25 on nTreg. Highly purified nTreg secreted IL‐6, IL‐10 and IL‐17A, but not IL‐2, IL‐4, IFN‐γ or TNF‐α. Taken together, our results demonstrate that hormones and nTreg modulate the diurnal rhythm of T helper cell activity.     

Diurnal cycle in salivary cortisol levels in common marmosets

A noninvasive method of saliva sampling was used to assess the diurnal cortisol rhythm from 0900 to 1700 hr in the common marmoset (Callithrix jacchus). The levels of cortisol were highest in the morning and declined significantly over the day. Individual marmosets varied in the magnitude of the cycle, and the greatest individual variability occurred in the morning levels. The decrease in cortisol levels was more rapid after than before the midday feeding period in subordinate marmosets (aged 53-63 months) compared to dominant marmosets (aged 79-80 months), and overall, the levels of cortisol were higher in the subordinate marmosets. We found no effect of sex on cortisol levels across the cycle.     

Effects of dose and dosing schedule of inhaled budesonide on bone turnover

To assess whether the use of larger than usual doses of inhaled steroid to treat severe asthma may adversely affect bone turnover and whether such an effect may be mitigated by altering the dose schedule, we investigated the effects of budesonide (BUD) on serum osteocalcin and the urinary output of hydroxyproline and calcium. Healthy adults were administered 1.2 or 2.4 mg of BUD per day (N = 40) or placebo (N = 8) in a crossover, double-blind comparison of morning versus diurnal dosing schedules for 1 month each. Both BUD doses reduced the 24-hour urinary free-cortisol output (p less than 0.001) and serum osteocalcin (p less than 0.001). The larger dose reduced the morning serum cortisol levels (p = 0.002). Neither dose increased the 8 AM urinary calcium or hydroxyproline output. Osteocalcin and plasma cortisol levels were higher on morning than on diurnal dosing (p = 0.01). The 24-hour urinary free-cortisol output was the same with either schedule (p = 0.96). Additional study is required to assess the clinical importance of the inhibitory effect of BUD on bone formation, as evidenced by the reduction in osteocalcin levels. Of concern is the possibility of serious bone complications resulting from the long-term use of inhaled steroid, particularly in growing children or patients in whom other risk factors for osteoporosis are present. The clinical advantage, if any, of morning dosing remains questionable.     

YKL-40, a biomarker of inflammation, is elevated in patients with type 2 diabetes and is related to insulin resistance

Objective and design. YKL-40 participates in inflammatory states and vascular processes, which implies that comparison can be made with other inflammatory markers associated with insulin resistance and type 2 diabetes (T2D). In the present study levels of plasma YKL-40 and serum hsCRP were evaluated in patients with T2D. Materials and methods. Patients with T2D and age-matched healthy controls participated in the study. Insulin resistance was estimated using HOMA-IR model. Biochemical parameters were measured in venous blood after a 10 h fast. Results. Patients with T2D were insulin resistant (p < 0.001) and had raised levels of plasma YKL-40 (p < 0.001) and serum hsCRP (p < 0.001). YKL-40 was correlated with HOMA-IR (r = 0.23, p < 0.01), NEFA (r = 0.32, p < 0.001) and triglycerides (r = 0.24, p < 0.05). YKL-40 and hsCRP were not correlated (r = 0.17, p = NS). All participants with hsCRP < 1 mg/l had higher insulin sensitivity (p < 0.05 and p < 0.01, respectively). HsCRP were predicted by HOMA-IR and BMI (r² = 0.48, p < 0.01). Plasma YKL-40 was predicted by HOMA-IR and triglycerides (r² = 0.27, p < 0.01). Conclusions. YKL-40 and hsCRP are elevated in patients with T2D and are related to insulin resistance. No correlation was found between YKL-40 and hsCRP indicating that increased levels of YKL-40 occur independently from elevated plasma hsCRP. Received 17 September 2005; returned for revision 17 October 2005; accepted by I. Ahnfelt-R?nne 18 October 2005     

beta(1)-adrenergic antagonists improve sleep and behavioural disturbances in a circadian disorder, Smith-Magenis syndrome

Smith-Magenis syndrome (SMS) is a clinically recognisable contiguous gene syndrome ascribed to interstitial deletions of chromosome 17p11.2. Patients have a phase shift of their circadian rhythm of melatonin with a paradoxical diurnal secretion of the hormone. Serum melatonin levels and day-night behaviour were studied in nine SMS children (aged 4 to 17 years) given acebutolol, a selective β₁-adrenergic antagonist (10 mg/kg early in the morning). Cardiac examination, serum melatonin, motor activity recordings, and sleep diaries were monitored before and after drug administration. The present study shows that a single morning dose of acebutolol suppressed the inappropriate secretion of melatonin in SMS. A significant improvement of inappropriate behaviour with increased concentration, delayed sleep onset, increased hours of sleep, and delayed waking were also noted. These results suggest that β₁-adrenergic antagonists help to manage hyperactivity, enhance cognitive performance, and reduce sleep disorders in SMS.


Keywords: Smith-Magenis syndrome; circadian rhythms; melatonin     

The daily course of the symptomatology and the impaired time estimation in endogenous depression (melancholia)

The importance of 'typical' diurnal variations in mood (depression worse in the morning) as a diagnostic criterion of endogenous depression has been challenged in previous investigations. Disturbance in time experience may contribute towards an understanding of diurnal variation in depressive symptomatology. To examine this hypothesis a series of time estimation experiments was conducted in the course of the day. Twenty-five endogenous depressive patients (according to ICD-9) and 12 healthy controls were asked to estimate prospectively a 30-s interval on two successive days at 7.30 a.m., 11.30 a.m., 3.30 p.m. and 7.30 p.m. Simultaneously the subjects assessed their state of well-being using a visual analogue mood scale. A circadian rhythm of time estimation errors could not be detected; even in daily courses with 'typical' diurnal variations an increasingly favourable self-assessment of well-being was not accompanied by a corresponding diurnal fluctuation of time estimation. These results cast additional doubts on the significance of 'typical' diurnal variations in depressive symptomatology.     

Non-steroidal anti-inflammatory drugs in rheumatoid arthritis

Fourteen patients with classical or definite rheumatoid arthritis were studied for the effect of piroxicam treatment on clinical parameters and cellular immunity. The treatment caused reduced disease activity as assayed by an augmented grip strength, reduced total stiffness, reduced duration of morning stiffness and reduced Ritchies articular index. No effect of the treatment was observed on the percentages of T₈ and T₄ positive cells nor on the natural killer (NK) cell activity in the peripheral blood mononuclear cells. In contrast, the treatment led to a reduction in the total amount of rheumatoid factor. Since rheumatoid factor is mainly produced locally in the inflamed synovial membranes, our results suggest an effect of piroxicam on the immune system locally but not in the peripheral blood.     

Comparison of bronchial responses to prostaglandin F2α and methacholine

We examined bronchial responsiveness to prostaglandin (PG) F_2α to determine its applicability in clinical practice and to compare it with bronchial responsiveness to the pharmacologically dissimilar agent, methacholine. Inhalation tests with twofold increasing concentrations of the two agents were carried out in 19 asthmatic and four normal subjects. The results were expressed as the provocation concentration causing a 20% fall in forced expiratory volume in 1 sec (PC₂₀). The range of concentrations required to determine the PC₂₀ was greater with PGF_2α (0.0001 to <5 mg/ml) than that with methacholine (0.07 to 30.96 mg/ml). Side effects of cough, retrosternal irritation, and expectoration of sputum were more frequent after PGF_2α. Repeat measurements in the same subjects showed that responses to PGF_2α were as highly reproducible (r = 0.98, p < 0.001) as previously reported with methacholine, and there was a cumulative dose effect (p < 0.001). PC₂₀PGF_2α correlated with PC₂₀ methacholine (r = 0.5, p < 0.01), but to a lesser degree than was previously demonstrated between histamine and methacholine. The poorer correlation was explained by the results of four subjects tolerant to PGF_2α relative to methacholine, three of whom were aspirin (ASA) intolerant; the correlation was much stronger when these subjects were excluded from analysis (r = 0.91, p < 0.001). The results suggest that (1) PGF_2α is not a suitable agent to use in clinical practice to measure nonspecific bronchial responsiveness because of the wide dose range and unpleasant side effects, (2) the bronchial responsiveness of different individuals to PGF_2α and methacholine is usually well correlated and is thus unrelated to specific receptor activity, and (3) there is a relative reduction in responsiveness to PGF_2α in some asthmatics, particularly those with ASA intolerance.     

Time-of-day effect on nonthermal control of sweating response to maintained static exercise in humans

To investigate the influence of nonthermal factors in the time-of-day effect on the sweating response to maintained static exercise, eight healthy male subjects performed handgrip exercise at 20%, 35% and 50% maximal voluntary contraction (MVC) for 60 s at 0600 hours (morning) and at 1800 hours (evening). Oesophageal temperature (T _oes) before the experiment showed a diurnal rhythm [mean (SEM)] [36.3 (0.1) (morning) compared to 36.8 (0.1) °C (evening), P<0.01]. Experiments were conducted with subjects in a state of mild hyperthermia during which the mean skin temperature (T _sk) was kept constant at 35.5–36.5 °C using a water-perfused suit to activate sudomotor responses. The T _oes and mean T _sk remained stable during the pre-exercise, handgrip exercise and recovery periods. The response in sweating rate (ΔSR) on the chest and forearm to handgrip exercise increased significantly with increasing exercise intensity in both the morning and evening tests (P<0.05). The ΔSR on the palm did not change significantly with increasing exercise intensity in the morning test (P>0.1). During handgrip exercise at 50% MVC only, ΔSR on the chest, forearm and palm in the evening was significantly higher than in the morning (P<0.05). On the other hand, mean arterial blood pressure and the rating of perceived exertion during 50% MVC handgrip exercise were not significantly different between the morning and evening (P>0.1). These results indicate the presence of a time-of-day effect on nonthermal control of the sweating response to isometric handgrip exercise, and that this effect is dependent on exercise intensity. Electronic Publication     

Work family balance, stress, and salivary cortisol in men and women academic physicians

Background: The stress of medical practice has been recurrently studied, but work- and family-related determinants of health by gender remain under researched. Purpose: To test the hypothesis that cortisol excretion would be affected by the perceived severity of total workload imbalance. Method: By hierarchical regression analysis, the associations between work-family balance and diurnal salivary cortisol levels by sex in academic physicians (n = 40) were investigated. Results: Men physicians reported more paid work hours per week than women physicians and women more time in childcare, but their total working hours were similar. Controlling for sex and age, the mean of the diurnal cortisol release was associated with a combined effect of sex and responsibility at home. When morning cortisol, sex, and children at home were held constant, cortisol levels in the evening were associated with responsibility at home without significant gender interaction. Conclusion: With increasing responsibility at home, women and men reacted differently with regard to cortisol responses over the day. However, in the evening, controlling for the morning cortisol, these gender differences were not as obvious. These findings highlight traditional gender patterns among both women and men physicians in the challenge of finding a balance between work and family.