Myelin basic protein and neurofilament H in postmortem cerebrospinal fluid as surrogate markers of fatal traumatic brain injury.

The aim of this study was to investigate if the biomarkers myelin basic protein (MBP) and neurofilament-H (NF-H) yielded informative value in forensic diagnostics when examining cadaveric cerebrospinal fluid (CSF) biochemically via an enzyme-linked immunosorbent assay (ELISA) and comparing the corresponding brain tissue in fatal traumatic brain injury (TBI) autopsy cases by immunocytochemistry versus immunohistochemistry. In 21 trauma and 19 control cases, CSF was collected semi-sterile after suboccipital puncture and brain specimens after preparation. The CSF MBP (p = 0.006) and NF-H (p = 0.0002) levels after TBI were significantly higher than those in cardiovascular controls. Immunohistochemical staining against MBP and against NF-H was performed on cortical and subcortical samples from also biochemically investigated cases (5 TBI cases/5 controls). Compared to the controls, the TBI cases showed a visually reduced staining reaction against MBP or repeatedly ruptured neurofilaments against NF-H. Immunocytochemical tests showed MBP-positive phagocytizing macrophages in CSF with a survival time of > 24 h. In addition, numerous TMEM119-positive microglia could be detected with different degrees of staining intensity in the CSF of trauma cases. As a result, we were able to document that elevated levels of MBP and NF-H in the CSF should be considered as useful neuroinjury biomarkers of traumatic brain injury.

Effects of age and sex on the concentrations of glutamate and glutamine in the human brain.

PURPOSE: To determine the effects of age and sex on cerebral glutamate and glutamine concentrations in a large sample of healthy humans using a dedicated measuring and evaluation procedure. Exploratory examinations of other brain metabolites were also conducted. MATERIALS AND METHODS: In 118 healthy subjects aged 19 to 55 years (59 female) absolute concentrations of glutamate, glutamine, N-acetylaspartate (NAA), total creatine, and total choline (tCho) in voxels comprising the left hippocampus (HC) and the anterior cingulate cortex (ACC) were investigated using point-resolved spectroscopy with an echo time of 80 ms at 3 Tesla in combination with a reliable quantification procedure. Special care was taken to correct for multiple comparisons. RESULTS: An age-related decline of the concentrations of glutamate in both regions studied was observed whereas glutamine levels in ACC increased with age. Statistically significant sex-related differences were detected for glutamate in the HC and for tCho in the ACC. NAA decreased with age in both regions, the significance not surviving Bonferroni correction. CONCLUSION: The results demonstrate effects of age and gender on glutamate, glutamine, choline containing compounds, and NAA in healthy human brain. They add to the growing evidence for gender-specific differences in cerebral neurotransmission, metabolism, and structure across the lifespan.

Met carriers of BDNF Val66Met genotype show increased N-acetylaspartate concentration in the anterior cingulate cortex.

Decreased levels of N-acetylaspartate (NAA) and brain-derived neurotrophic factor (BDNF) in the anterior cingulate cortex (ACC) have been linked to neuronal loss and psychiatric disorders like schizophrenia and bipolar disorder. We previously found that BDNF serum concentration was predicted by the concentration of NAA in the ACC, indicating that neuronal integrity and vitality of a cortical region like the ACC, as reflected by a high concentration of NAA, might be related to high concentrations of BDNF in serum. Moreover, our recent finding that Val66Met genotype appears to predict the BDNF serum level in healthy human volunteers suggests the Met allele to be connected to higher concentrations of BDNF in serum. We examined absolute NAA concentrations in the ACC and hippocampus of 40 male and 42 female healthy volunteers (age: 33.3+/-9 years). We found NAA in the ACC to be significantly increased in Met carriers (F=5.2, df=1, p=0.025). On the other hand, the concentration of creatine+phosphocreatine in the hippocampus was significantly decreased in Met carriers. We hypothesize that higher NAA levels in the ACC might contribute to the protection of Met allele carriers against major psychiatric disorders as schizophrenia and bipolar disorder.

Diffusion- and reaction-limited growth of carbon nanotube forests.

We present a systematic study of the temperature and pressure dependence of the growth rate of vertically aligned small diameter (single- and few-walled) carbon nanotube forests grown by thermal chemical vapor deposition over the temperature range 560-800 degrees C and 10(-5) to 14 mbar partial pressure range, using acetylene as the feedstock and Al(2)O(3)-supported Fe nanoparticles as the catalyst. We observe a pressure dependence of P(0.6) and activation energies of <1 eV. We interpret this as a growth rate limited by carbon diffusion in the catalyst, preceded by a pre-equilibrium of acetylene dissociation on the catalyst surface. The carbon nanotube forest growth was recorded by high-resolution real-time optical imaging.

Ledge-flow-controlled catalyst interface dynamics during Si nanowire growth.

Self-assembled nanowires offer the prospect of accurate and scalable device engineering at an atomistic scale for applications in electronics, photonics and biology. However, deterministic nanowire growth and the control of dopant profiles and heterostructures are limited by an incomplete understanding of the role of commonly used catalysts and specifically of their interface dynamics. Although catalytic chemical vapour deposition of nanowires below the eutectic temperature has been demonstrated in many semiconductor-catalyst systems, growth from solid catalysts is still disputed and the overall mechanism is largely unresolved. Here, we present a video-rate environmental transmission electron microscopy study of Si nanowire formation from Pd silicide crystals under disilane exposure. A Si crystal nucleus forms by phase separation, as observed for the liquid Au-Si system, which we use as a comparative benchmark. The dominant coherent Pd silicide/Si growth interface subsequently advances by lateral propagation of ledges, driven by catalytic dissociation of disilane and coupled Pd and Si diffusion. Our results establish an atomistic framework for nanowire assembly from solid catalysts, relevant also to their contact formation.