Hypothalamic-pituitary-adrenal axis, childhood adversity and adolescent nonsuicidal self-injury.

BACKGROUND: Whereas childhood adversity (CA) and the hypothalamus-pituitary-adrenal (HPA) axis have been suggested to play a major role in the etiology of non-suicidal self-injury (NSSI), no study has thus far investigated both its associations and interactions with adolescent NSSI. METHOD: We investigated CA (antipathy, neglect, physical, psychological, and sexual abuse) and indices of HPA axis activity (salivary and hair cortisol) in a clinical sample of 26 adolescents engaging in NSSI and 26 age- and gender-matched healthy controls (HC). We used standardized interviews for the assessment of CA (CECA), NSSI (SITBI-G), and axis I diagnoses (MINI-KID). Salivary cortisol sampling was surveyed using a monitoring system and instructed via telephone calls. RESULTS: Adolescents engaging in NSSI exhibited significantly higher cortisol awakening responses compared to HC. No differences were found with respect to the diurnal slope or hair cortisol. In the presence of CA, healthy adolescents showed flatted diurnal cortisol slopes while those engaging in NSSI exhibited significantly steeper ones. CONCLUSIONS: Our findings indicate that adolescents engaging in NSSI may exhibit a stronger cortisol awakening response, potentially in expectation of strain. However, elevated cortisol levels may not be maintained throughout the day, especially among adolescents with a history of CA.

Temperature effect on the sulfur isotope fractionation during sulfate reduction by two strains of the hyperthermophilic Archaeoglobus fulgidus.

Sulfur isotope fractionation during dissimilatory sulfate reduction by two strains of the thermophilic archaeon Archaeoglobus fulgidus (strains VC-16 and Z) was explored over the entire temperature range of growth. The optimal cell-specific sulfate reduction rate (14 fmol cell(-1) h(-1)) was found at 82-84 degrees C but growth was measured as low as 54 degrees C. The fractionation ranged between 0.52 per thousand and 27 per thousand, with largest fractionations were found at intermediate temperatures and the smallest fractionations at the lowest and highest temperatures. There was an inverse relationship between the cell-specific sulfate reduction rate and fractionation, and the cell-specific rate was a good indicator of the expected fractionations regardless of whether temperature or substrate concentrations controlled the rate. Comparison of the fractionation trend found in this study with similar measurements for seven other sulfate-reducers showed that sulfate-reducing organisms respond to temperature in three different ways and this correlated with their maximum fractionation value, but not with the cell-specific sulfate reduction rate. A sulfur isotope model was used to reproduce the observed variation of fractionation with temperature. This approach predicted the rate of internal sulfur transformations as having the major influence on the observed fractionations in the intermediate temperature range, whereas the exchange of sulfate across the cell membrane controls fractionation at low and high temperatures.