The correlation between longitudinal changes in hypothalamic-pituitary-adrenal (HPA)-axis activity and changes in neurocognitive function in mixed-state bipolar II disorder.

INTRODUCTION: In this study, we aim to determine 1) the differences in cortisol in patients with bipolar II disorder (BD-II) and control subjects and 2) the correlation between cortisol levels and cognitive function in patients with BD-II during a 24-week follow-up period. METHODS: We recruited a total of 32 BD-II patients and 30 healthy control subjects. The BD-II patients were assessed for clinical severity and serum cortisol level at baseline and at weeks 8, 16, and 24. The Brief Assessment of Cognition in Affective Disorders (BACA) was adopted to evaluate cognitive function at baseline and endpoint (week 24). Meanwhile, we assessed the controls for serum cortisol level and BACA at baseline. RESULTS: We observed that the BD-II group had a higher serum cortisol level and lower BACA composite scores compared with the healthy controls at baseline. A significant correlation was found between changes in Verbal Fluency, a subset of BACA, and changes in serum cortisol level after the 24-week follow-up, controlling for age, gender, years of education, and clinical severity (P<0.001). CONCLUSION: We propose that serum cortisol may be involved in the psychopathological mechanisms of cognitive decline in BD-II.

Serum DHEA-S concentration correlates with clinical symptoms and neurocognitive function in patients with bipolar II disorder: A case-controlled study.

OBJECTIVES: Dysregulation of the neuroendocrine system including dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEA-S), and pregnenolone may play a role in the pathophysiology of bipolar II disorder (BP-II). The aims of the current study are to determine (a) the differences in DHEA, DHEA-S and pregnenolone in patients with BP-II and controls; and (b) the correlation of levels of the above hormones, cognitive function, and clinical symptoms. METHODS: Patients diagnosed with BP-II and healthy controls were recruited from psychiatric department. Blood samples were collected to measure the levels of DHEA, DHEA-S and pregnenolone in all participants, followed by assessment of cognitive function using the Brief Assessment of Cognition in Affective Disorders (BACA). RESULTS: A total of 32 patients BP-II and 30 healthy control subjects were recruited. The BP-II group was found with significantly elder age, fewer years of education, and lower BACA composite scores compared to the healthy controls. The level of DHEA-S was significantly associated with performance in BACA when controlling for age, gender, years of education and having BP-II (P=0.018). The DHEA-S level was significantly correlated with mania score (r=-0.498, P=0.010). CONCLUSION: Our findings support that serum level of DHEA-S may be a biomarker representing clinical manic symptoms and cognitive performance.

Sorbitol counteracts temperature- and chemical-induced denaturation of a recombinant α-amylase from alkaliphilic Bacillus sp. TS-23.

Enzymes are highly complex systems with a substantial degree of structural variability in their folded state. In the presence of cosolvents, fluctuations among vast numbers of folded and unfolded conformations occur via many different pathways; alternatively, certain conformations can be stabilized or destabilized. To understand the contribution of osmolytes to the stabilization of structural changes and enzymatic activity of a truncated Bacillus sp. TS-23 α-amylase (BACΔNC), we monitored amylolytic activity, circular dichroism, and fluorescence as a function of osmolytes. In the presence of trimethylamine N-oxide (TMAO) and sorbitol, BACΔNC activity was retained significantly at elevated temperatures. As compared to the control, the secondary structures of this enzyme were essentially conserved upon the addition of these two kinds of osmolytes. Fluorescence results revealed that the temperature-induced conformational change of BACΔNC was prevented by TMAO and sorbitol. However, glycerol did not provide profound protection against thermal denaturation of the enzyme. Sorbitol was further found to counteract guanidine hydrochloride- and SDS-induced denaturation of BACΔNC. Thus, some well-known naturally occurring osmolytes make a dominant contribution to the stabilization of BACΔNC.