The Sod2 gene for Mn-superoxide dismutase (MnSOD), an intramitochondrial free radical scavenging enzyme that is the first line of defense against superoxide produced as a byproduct of oxidative phosphorylation, was inactivated by homologous recombination. Homozygous mutant mice die within the first 10 days of life with a dilated cardiomyopathy, accumulation of lipid in liver and skeletal muscle, and metabolic acidosis. Cytochemical analysis revealed a severe reduction in succinate dehydrogenase (complex II) and aconitase (a TCA cycle enzyme) activities in the heart and, to a lesser extent, in other organs. These findings indicate that MnSOD is required for normal biological function of tissues by maintaining the integrity of mitochondrial enzymes susceptible to direct inactivation by superoxide.

Using longitudinal data from the 4-H Study of Positive Youth Development, the authors assessed 1,977 adolescents across Grades 5 to 8 to determine if there were distinctive developmental paths for behavioral and emotional school engagement; if these paths varied in relation to sex, race/ethnicity, and family socioeconomic status (SES); and whether links existed between trajectories of school engagement and grades, depression, substance use, and delinquency. Four trajectories for behavioral school engagement and four trajectories of emotional engagement were identified using a semiparametric mixture model. These trajectories were distinct with regard to initial levels of and changes in engagement, as well as to their shapes. Trajectories varied in regard to sex, SES, and race/ethnicity. Different trajectories of behavioral and emotional engagement were linked to grades, depression, delinquency, and substance use. Directions for future research and application are discussed.

3515wileyonlinelibrary.com OER and HER catalysts based on the earth-abundant fi rst row transition metals (Fe, Co, and Ni, etc.) has received extensive research interest. [9][10][11][12][13] Although signifi cant progress has been achieved, great challenges remain for nonprecious catalysts to achieve activity and stability that are comparable to conventional precious metals. To this end, one promising approach is to develop multimetallic/carbon catalysts by taking advantage of abundant metal-metal and metal-carbon synergistic interactions to enhance the performance of nonprecious catalysts. [14][15][16] The NiFe (oxy)hydroxide-based catalysts are regarded as one of the best performing nonprecious OER electrocatalysts in alkaline solutions, [17][18][19][20][21] which can be synthesized by coupling with carbon nanotube or graphene to achieve better conductivity and synergistic effects via hydrothermal, [ 19,22 ] or electrodeposition onto gold, glassy carbon, and nickel foam, etc., conductive current collector substrates. [ 19,23,24 ] The high OER activities of NiFe catalysts are generally attributed to a strong synergistic effect upon the incorporation of Fe, even in trace amount, into NiOOH, although the complete mechanisms and structural characteristics are not yet fully understood. [ 19,23 ] NiFe catalysts also have been reported for HER in alkaline media, [ 25 ] although the synergistic effect for HER is not as signifi cant as that for OER, and the reported activity for HER is relatively low compared to state-of-the-art nonprecious HER catalysts. Nevertheless, using the same catalyst as both the anode and cathode in an electrolysis device is very attractive, which could not only signifi cantly improve the integration and simplifi cation of the water splitting system, but also provide the feasibility of industrial application of water splitting technology.Besides having an effi cient catalyst, rational design of catalyst structure is known to be crucial for improving the electrode performance. In pursuit of creating large surface area and high active site density, various attempts have been devoted to developing 3D nanostructured catalyst materials, [26][27][28] such as mesoporous NiFe nanosheets, [ 24 ] NiCo 2 O 4 nanosheets/halloysite nanotubes, [ 26 ] hierarchically structured carbon microfi bre, [ 29 ] and multilayered TiO 2 nanowire arrays. [ 30 ] Moreover, smart design of a catalyst with macroscopic structure onto conductive porous support (e.g., nickel foam) could afford Bifunctional Porous NiFe/NiCo 2 O 4 /Ni Foam Electrodes with Triple Hierarchy and Double Synergies for Effi cient Whole Cell Water SplittingChanglong Xiao , Yibing Li , Xunyu Lu , and Chuan Zhao * A 3D hierarchical porous catalyst architecture based on earth abundant metals Ni, Fe, and Co has been fabricated through a facile hydrothermal and electrodeposition method for effi cient oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The electrode is comprised of three levels of porous structures including the bottom su...

Mitochondrial injury has been implicated in ischemic neuronal injury. Mitochondria, producing adenosine triphosphate by virtue of electron flow, have been shown to be both the sites of superoxide anion (O2-) production and the target of free radical attacks. We evaluated these mechanisms in an in vivo cerebral ischemia model, using mutant mice with a heterozygous knock-out gene (Sod2 -/+) encoding mitochondrial manganese superoxide dismutase (Mn-SOD). Sod2 -/+ mice demonstrated a prominent increase in O2- production under normal physiological conditions and in ischemia, as evidenced by specific oxidation of a fluorescent probe, hydroethidine, reflecting decreased activity of Mn-SOD. A mitochondrial viability assay that used rhodamine 123, which is accumulated by transmembrane potential of viable mitochondria, demonstrated accelerated development of mitochondrial injury. This rapid progress of ischemic injury resulted in exacerbation of infarct size and hemisphere enlargement, causing advanced neurological deficits but without altering DNA fragmentation induction. The present study suggests that O2- overproduced in a mitochondrial compartment, when uncoupled from antioxidant defenses, induces impairment of mitochondrial function and causes exacerbation of cerebral infarction after ischemia.

The understanding of positive development across adolescence rests on having a valid and equivalent measure of this construct across the breadth of this period of life. Does the Positive Youth Development (PYD) construct based on the Five Cs model have satisfactory psychometric properties for such longitudinal measurement invariance? Using longitudinal data derived from the 4-H Study of PYD, we assessed 920 youth (61.6% female) from a racially and ethically diverse sample (67.3% European American) who participated in three waves (Grades 8-10) of data collection. Building on prior findings that the Five Cs (i.e., Competence, Confidence, Connection, Character, and Caring) model of PYD was a robust measure that could be assessed comparably during early adolescence, we tested a hierarchy of second-order confirmatory factor analysis models to assess the extent to which PYD can be measured equivalently across middle adolescence. Evidence was found for strict measurement invariance across three measurement occasions, including equivalence of first-order and second-order factor loadings, equality of intercepts of observed variables, and equality of item uniqueness and disturbances of the first-order factors. These results suggest that PYD can be measured in the same way across measurement occasions, a prerequisite for the study of development. Implications for research and application of being able to measure PYD equivalently across adolescence are discussed.