Long-term exposure to high altitude reduces alpha and beta bands event-related desynchronization in a Go/NoGo task.

More than 80 million people worldwide permanently live at high altitudes, and living in such a hypoxic environment can impair cognitive functions. However, it is largely unknown how long-term exposure to high altitude affects neural oscillations underlying these cognitive functions. The present study employed a Go/NoGo task to investigate the effects of long-term exposure to high altitude on neural oscillations during cognitive control. We compared event-related spectral perturbations between the low-altitude and high-altitude groups, and the results revealed increased theta event-related synchronization (ERS) and decreased alpha and beta event-related desynchronizations (ERDs) during the NoGo condition compared to the Go condition. Importantly, the high-altitude group showed reduced alpha and beta ERDs compared to the low-altitude group, while the theta ERS was not affected by altitude. We suggest that long-term exposure to high altitude has an impact on top-down inhibitory control and movement preparation and execution in the Go/NoGo task.

Interactive effect between sleep and exercise on depressive symptoms in Chinese adolescents.

Objectives: The study aimed to investigate the effects of sleep and exercise, individually and jointly, on depressive symptoms in Chinese adolescents. Methods: Cluster sampling was used to conduct a cross-sectional, electronic survey among 11,563 students from five primary and high schools in Sichuan Province in Western China. The questionnaire contained custom-designed items concerning sleep and exercise, while it used the Center for Epidemiologic Studies Depression Scale to assess depressive symptoms and the Core Self-Evaluations Scale to assess core self-evaluation. Data were analyzed using descriptive statistics and multivariate linear regression. Results: A total of 10,185 valid questionnaires were collected, corresponding to an effective response rate of 88.1%. Among the respondents in the final analysis, 5,555 (54.5%) were boys and 4,630 (45.5%) were girls, and the average age was 15.20 ± 1.72 years (range, 11-18 years). Only less than half of the respondents (4,914, 48.2%) reported insufficient sleep, while the remainder (5,271, 51.8%) had adequate sleep. Nearly one-quarter (2,250, 22.1%) reported insufficient exercise, while the remainder (7,935, 77.9%) reported adequate exercise. More than half of the respondents (5,681, 55.7%) were from vocational high school, 3,368 (33.1%) were from junior high school, 945 (9.3%) were from senior high school, and 191 (1.9%) were from primary school. The prevalence of depressive symptoms among all respondents was 29.5% (95% CI 28.7%-30.4%). When other variables were controlled, the depression score did not vary significantly with gender (B = -0.244, SE = 0.127, P = 0.054), but it decreased by 0.194 points per 1-year increase in age (B = -0.194, SE = 0.037, P < 0.001). Students getting adequate sleep had depression scores 2.614 points lower than those getting insufficient sleep (B = -2.614, SE = 0.577, P < 0.001), while students who engaged in adequate exercise had depression scores 1.779 points lower than those not exercising enough (B = -1.779, SE = 0.461, P < 0.001). The depression score decreased by 0.919 points per 1-point increase in the core self-evaluation score (B = -0.919, SE = 0.008, P < 0.001). In regression controlling for gender, age, and core self-evaluation, sleep and exercise were found to be related significantly to influence depressive symptoms (B = 0.821, SE = 0.315, P = 0.009). Conclusion: Adequate sleep and adequate exercise are individually associated with milder depressive symptoms in Chinese adolescents. Our results further highlight the need for researchers and clinicians to take into account not only the individual but also the joint effects of sleep and exercise on depression in adolescents when conducting research and designing interventions. If sleep or physical exercise has substantially reduced the risk of depressive symptoms, further reductions by improving sleep and exercise become difficult and may even have opposite effects.

Core self-evaluation as mediator between depressive symptoms and suicidal ideation in adolescents.

OBJECTIVES: To explore the role of core self-evaluation in mediating between depressive symptoms and suicidal ideation in Chinese adolescents. METHODS: We used the cluster sampling method to analyze 11,563 students from five primary and secondary schools in China for depressive symptoms, core self-evaluation, and suicidal ideation using the following scoring scales: Core Self-Evaluation Scale (CSES), Center for Epidemiologic Survey Depression Scale (CES-D), the Second Edition of the Beck Depression Inventory (BDI- II), Screen for Child Anxiety Related Emotional Disorders (SCARED), and Adolescent Self-Rating Life Events Checklist (ASLEC). RESULTS: The incidence of depression was 29.7%; anxiety, 34.2%; and suicidal ideation, 28.0%. Core self-evaluation was a protective factor for suicidal ideation [OR 0.947, 95% CI 0.937-0.959, p<0.001]. Conversely, depression as measured by the CSES score was a risk factor for suicidal ideation (OR 1.084, 95% CI 1.073-1.096, p<0.001), as were anxiety as measured by the SCARED score (OR 1.011, 95% CI 1.006-1.016, p<0.001) and adolescent life events according to ASLEC score groups (OR 1.524, 95% CI 1.434-1.621, p<0.001). Core self-evaluation mediated the relationship between depression and suicidal ideation with an effect size of 13.9%. CONCLUSIONS: Better core self-evaluation is a protective factor against suicidal ideation and mediates the relationship between depression and suicidal ideation. We may be able to reduce the risk of suicidal ideation and therefore suicide among adolescents by improving their core self-evaluation.

Retinal counterion switch in the photoactivation of the G protein-coupled receptor rhodopsin.

The biological function of Glu-181 in the photoactivation process of rhodopsin is explored through spectroscopic studies of site-specific mutants. Preresonance Raman vibrational spectra of the unphotolyzed E181Q mutant are nearly identical to spectra of the native pigment, supporting the view that Glu-181 is uncharged (protonated) in the dark state. The pH dependence of the absorption of the metarhodopsin I (Meta I)-like photoproduct of E181Q is investigated, revealing a dramatic shift of its Schiff base pKa compared with the native pigment. This result is most consistent with the assignment of Glu-181 as the primary counterion of the retinylidene protonated Schiff base in the Meta I state, implying that there is a counterion switch from Glu-113 in the dark state to Glu-181 in Meta I. We propose a model where the counterion switch occurs by transferring a proton from Glu-181 to Glu-113 through an H-bond network formed primarily with residues on extracellular loop II (EII). The resulting reorganization of EII is then coupled to movements of helix III through a conserved disulfide bond (Cys110-Cys187); this process may be a general element of G protein-coupled receptor activation.

Volume changes and electrostriction in the primary photoreactions of various photosynthetic systems: estimation of dielectric coefficient in bacterial reaction centers and of the observed volume changes with the Drude-Nernst equation.

Photoacoustics (PA) allows the determination of enthalpy and volume changes of photoreactions in photosynthetic reaction centers on the 0.1-10 mus time scale. These include the bacterial centers from Rb. sphaeroides, PS I and PS II centers from Synechocystis and in whole cells. In vitro and in vivo PA data on PS I and PS II revealed that both the volume change (-26 A(3)) and reaction enthalpy (-0.4 eV) in PS I are the same as those in the bacterial centers. However the volume change in PS II is small and the enthalpy far larger, -1 eV. Assigning the volume changes to electrostriction allows a coherent explanation of these observations. One can explain the large volume decrease in the bacterial centers with an effective dielectric coefficient of approximately 4. This is a unique approach to this parameter so important in estimation of protein energetics. The value of the volume contraction for PS I can only be explained if the acceptor is the super- cluster (Fe(4)S(4))(Cys(4)) with charge change from -1 to -2. The small volume change in PS II is explained by sub-mus electron transfer from Y(Z) anion to P(680) cation, in which charge is only moved from the Y(Z) anion to the Q(A) with no charge separation or with rapid proton transfer from oxidized Y(Z) to a polar region and thus very little change in electrostriction. At more acid pH equally rapid proton transfer from a neighboring histidine to a polar region may be caused by the electric field of the P(680) cation.