Lower N-Acetyl-Aspartate Levels in Prefrontal Cortices in Pediatric Bipolar Disorder: A (1)H Magnetic Resonance Spectroscopy Study

Objective: The few studies applying single-voxel(1)H spectroscopy in children and adolescents with bipolar disorder (BD) have reported low N-acetyl-aspartate (NAA) levels in the dorsolateral prefrontal cortex (DLPFC), and high myo-inositol / phosphocreatine plus creatine (PCr+Cr) ratios in the anterior cingulate. The aim of this study was to evaluate NAA, glycerophosphocholine plus phosphocholine (GPC+PC) and PCr+Cr in various frontal cortical areas in children and adolescents with BD. We hypothesized that NAA levels within the prefrontal cortex are lower in BD patients than in healthy controls, indicating neurodevelopmental alterations in the former. Method: We studied 43 pediatric patients with DSM-IV BD (19 female, mean age 13.2 +/- 2.9 years) and 38 healthy controls (79 female, mean age 13.9 +/- 2.7 years). We conducted multivoxel in vivo (1)H spectroscopy measurements at 1.5 Tesla using a long echo time of 272 ms to obtain bilateral metabolite levels from the medial prefrontal cortex (MPFC), DLPFC (white and gray matter), cingulate (anterior and posterior), and occipital lobes. We used the nonparametric Mann-Whitney U test to compare neurochemical levels between groups. Results: In pediatric BD patients, NAA and GPC+PC levels in the bilateral MPFC, and PCr+Cr levels in the left MPFC were lower than those seen in the controls. In the left DLPFC white matter, levels of NAA and PCr+Cr were also lower in BD patients than in controls. Conclusions: Lower NAA and PCr+Cr levels in the PFC of children and adolescents with BD may be indicative of abnormal dendritic arborization and neuropil, suggesting neurodevelopmental abnormalities. J. Am. Acad. Child Adolesc. Psychiatry, 2011;50(1):85-94.University of Texas Health Science Center at San Antonio (UTHSCSA) General Clinical Research Center (GCRC)[M01-RR-01346]UTHSCSA Krus Endowed Chair in PsychiatryCoordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES) Foundation of BrazilFundacao de Amparo a Pesquisa de Sao Paulo, Brazil (FAPESP)Conselho Nacional de Desenvolvimento Cientifico e Tecnologico, Brazil (CNPq)National Alliance for Research on Schizophrenia and Depression (NARSAD)American Psychiatric Association/AstraZenecaOrtho-McNeil Janssen and Shire Inc.PfizerGlaxoSmithKlineRepligen[MH 01736][MH 69774][MH 068662][RR 020571

Texture Change in Pure Mg and Mg-1.5wt% Mn Casting Alloy During Compressive Creep-Deformation

Most magnesium alloys undergo creep under the service conditions of the automotive powertrain components (50- 100MPa, 175-200\ubaC). Texture studies on creep-tested pure Mg and Mg-1.5wt%Mn casting alloys were performed via Neutron Diffraction (ND). Analysis of the as-cast pure Mg, before creep testing indicated that there is preferred orientation with the c-axis of the HCP grains perpendicular to the growth direction of the columnar grains (and parallel to the longitudinal axis of the casting). Following compressive-creep testing (15MPa, 175\ubaC, 150hrs.), the maximum intensity of the texture in pure Mg dropped notably, indicating a rotation of basal-plane normals. No significant change in the maximum intensity of texture was observed in Mg-1.5%Mn samples creep tested under the same conditions. Creep tests conducted at 50MPa (which is above the yield strength of the alloys) and at 150\ubaC on both pure Mg and Mg-1.5%Mn samples resulted in the rotation of the basal plane normals towards the compression axis.Peer reviewed: YesNRC publication: Ye

Phase formation in as-solidified and heat-treated Al–Si–Cu–Mg–Ni alloys: Thermodynamic assessment and experimental investigation for alloy design

Thermodynamic simulations based on the CALPHAD method have been carried out to assess the phase formation in Al–7Si–(0–1)Ni–0.5Cu–0.35Mg alloys (in wt.%) under equilibrium and non-equilibrium (Scheil cooling) conditions. Calculations showed that the T-Al9FeNi, γ-Al7Cu4Ni, δ-Al3CuNi and ε-Al3Ni phases are formed at different Ni levels. By analyzing the calculated isothermal sections of the phase diagrams it was revealed that the Ni:Cu and Ni:Fe ratios control precipitation in this alloy system. In order to verify the simulation results, microstructural investigations in as-cast, solution treated and aged conditions were carried out using electron probe microanalysis (EPMA), scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Furthermore, cooling curve analysis (CCA) was also performed to determine the freezing range of the new alloys and porosity formation during solidification. Hardness measurements of the overaged samples showed that in this alloy system the δ-Al3CuNi phase has a greater influence on the overall strength of the alloys compared to the other Ni-bearing precipitates