Association of occupational stress with waking, diurnal, and bedtime cortisol response in police officers.

OBJECTIVE: Police officers have higher rates of cardiovascular disease (CVD) morbidity and mortality than the U.S. general population. Officers are exposed to conventional and unexpected workplace stressors. The hypothalamic-pituitary-adrenal (HPA) axis plays a major role responding to stressor exposure by releasing cortisol. Prolonged release or excessive levels may result in disease. Our study investigated cross-sectional associations between self-reported work stress and various salivary cortisol parameters. METHODS: A total of 285 police officers (76.5% male) from the Buffalo Cardio-Metabolic Occupational Police Stress (BCOPS) Study (2004-2009) completed the Spielberger Police Stress Survey, reporting frequency and severity of work events during the past month and year to calculate stress indices. Officers provided saliva samples to measure levels of cortisol secretion. Linear regression assessed associations between stress indices and various cortisol parameters, adjusted for age, gender, race/ethnicity, abdominal height, and smoking status. RESULTS: Significant positive associations were observed between stress indices (overall stress, physical danger stress, and past-month lack of support) and diurnal cortisol (AUCg: total area under the curve). Administrative, overall, and physical danger stress in the past year were significantly associated with the diurnal slope. Overall, administrative, and physical danger stress were significantly associated with bedtime levels. There were no significant associations between the stress indices and the awakening cortisol parameters. CONCLUSIONS: Higher stress ratings were related to blunted diurnal decline in cortisol, suggesting conventional and unexpected police stressors may result in HPA axis dysfunction. Future studies investigating possible associations between elevated cortisol and subclinical CVD are needed.

Alterations in cardiomyocyte function after pulmonary treatment with stainless steel welding fume in rats.

Welding fume is composed of a complex of different metal particulates. Pulmonary exposure to different welding fumes may exert a negative impact on cardiac function, although the underlying mechanisms remain unclear. To explore the effect of welding fumes on cardiac function, Sprague-Dawley rats were exposed by intratracheal instillation to 2 mg/rat of manual metal arc hard surfacing welding fume (MMA-HS) once per week for 7 wk. Control rats received saline. Cardiomyocytes were isolated enzymatically at d 1 and 7 postexposure. Intracellular calcium ([Ca(2+)]i) transients (fluorescence ratio) were measured on the stage of an inverted phase-contrast microscope using a myocyte calcium imaging/cell length system. Phosphorylation levels of cardiac troponin I (cTnI) were determined by Western blot. The levels of nonspecific inflammatory marker C-reactive protein (CRP) and proinflammatory cytokine interleukin-6 (IL-6) in serum were measured by enzyme-linked immunosorbent assay (ELISA). Contraction of isolated cardiomyocytes was significantly reduced at d 1 and d 7 postexposure. Intracellular calcium levels were decreased in response to extracellular calcium stimulation at d 7 postexposure. Changes of intracellular calcium levels after isoprenaline hydrochloride (ISO) stimulation were not markedly different between groups at either time point. Phosphorylation levels of cTnI in the left ventricle were significantly lower at d 1 postexposure. The serum levels of CRP were not markedly different between groups at either time point. Serum levels of IL-6 were not detectable in both groups. Cardiomyocyte alterations observed after welding fume treatment were mainly due to alterations in intracellular calcium handling and phosphorylation levels of cTnI.

The cortisol response in policemen: intraindividual variation, not concentration level, predicts truncal obesity.

OBJECTIVES: Chronic stress, characteristic of police work, affects the hypothalamic-pituitary-adrenal axis' control of cortisol production. Capacity to vary cortisol may be the appropriate measurement to interpret associations with chronic diseases, including obesity, best measured by variability within a person, not central tendency. METHODS: On each of 217 policemen, 18 saliva specimens were obtained for cortisol. Statistical models examined the associations of within-subjects (W-S) cortisol standard deviation (SD) and W-S cortisol mean with waist circumference and four body composition indexes: BMI, and three derived from DEXA: fat-mass, and trunk and extremities lean-mass. Explained variance and the functional nature of associations are reported. RESULTS: Associations of anthropometrics with W-S cortisol mean were not statistically significant at P < 0.05; all associations with W-S cortisol SD were significant. The association of trunk lean mass index (LMIt ) with W-S cortisol SD dominated all models. Associations of W-S cortisol SD with other indexes vanished when models contained LMIt ; when any other index was included in models predicting LMIt , associations with W-S cortisol SD remained significant. The functional association between LMIt and W-S cortisol SD is progressively "hockey stick," monotonic increasing, and flattens at joint high values. CONCLUSIONS: Results support inferences that LMIt measures visceral adiposity and W-S cortisol variability appears to be an appropriate construct to measure in association with visceral adiposity. The "hockey stick" character of the association is consistent with other investigations suggesting obesity is associated with less W-S cortisol variation; however, the monotonic increase and flattening of association at increasing W-ScortisolSD values suggests a more complex association, potentially interpretable by allostasis models of causation.

Area under the curve and other summary indicators of repeated waking cortisol measurements.

OBJECTIVE: To derive the area under the curve and related summary measures of stress from saliva samples collected over time and to provide insight into the interpretation of the derived parameters. In research designed to assess the health consequences of stress these samples are often used as a physiologic indicator of the responsiveness of the hypothalamic-pituitary-adrenal (HPA) axis. To make these repeated measurements of salivary cortisol more useful in defining the relationships between stress and health there is a need to derive two forms of area under the curve that summarize the measurements: area under the curve with respect to ground (AUC(G)) and area under the curve with respect to increase (AUC(I)). The latter parameters, AUC(I), however, is seldom used by research scientists. METHODS: In this study, interpretation and generic definition of the area under the curve was provided through graphical analyses and examination of its association with other summary measures using data from the Buffalo Cardio-Metabolic Occupational Police Stress (BCOPS) Pilot Study. In generic form, AUC(I) is derived as the area under the curve above the baseline value minus the area above the curve below the baseline value. RESULTS: The sign and magnitude of AUC(I) are related to the profile and the rate of change of the measurements over time. The parameter showed significant associations with other summary indicators that measure pattern or rate of change of the measurements over time. CONCLUSION: Principal components analyses revealed that summary parameters derived from repeated cortisol measurements can be grouped into two meaningful general categories: measures of the magnitude of response and measures of the pattern of response over time.