New Samarium and Neodymium based admixed ferromagnets with near zero net magnetization and tunable exchange bias field

Rare earth based intermetallics, SmScGe and NdScGe, are shown to exhibit near zero net magnetization with substitutions of 6 to 9 atomic percent of Nd and 25 atomic percent of Gd, respectively. The notion of magnetic compensation in them is also elucidated by the crossover of zero magnetization axis at low magnetic fields (less than 103 Oe) and field-induced reversal in the orientation of the magnetic moments of the dissimilar rare earth ions at higher magnetic fields. These magnetically ordered materials with no net magnetization and appreciable conduction electron polarization display an attribute of an exchange bias field, which can be tuned. The attractively high magnetic ordering temperatures of about 270 K, underscore the importance of these materials for potential applications in spintronics.Comment: 6 page text + 5 figure

Glucocerebrosidases catalyze a transgalactosylation reaction that yields a newly-identified brain sterol metabolite, galactosylated cholesterol

?-Glucocerebrosidase (GBA) hydrolyzes glucosylceramide (GlcCer) to generate ceramide. Previously, we demonstrated that lysosomal GBA1 and nonlysosomal GBA2 possess not only GlcCer hydrolase activity, but also transglucosylation activity to transfer the glucose residue from GlcCer to cholesterol to form ?-cholesterylglucoside (?-GlcChol) in vitro. ?-GlcChol is a member of sterylglycosides present in diverse species. How GBA1 and GBA2 mediate ?-GlcChol metabolism in the brain is unknown. Here, we purified and characterized sterylglycosides from rodent and fish brains. Although glucose is thought to be the sole carbohydrate component of sterylglycosides in vertebrates, structural analysis of rat brain sterylglycosides revealed the presence of galactosylated cholesterol (?-GalChol), in addition to ?-GlcChol. Analyses of brain tissues from GBA2-deficient mice and GBA1- and/or GBA2-deficient Japanese rice fish (Oryzias latipes) revealed that GBA1 and GBA2 are responsible for ?-GlcChol degradation and formation, respectively, and that both GBA1 and GBA2 are responsible for ?-GalChol formation. Liquid chromatography?tandem MS revealed that ?-GlcChol and ?-GalChol are present throughout development from embryo to adult in the mouse brain. We found that ?-GalChol expression depends on galactosylceramide (GalCer), and developmental onset of ?-GalChol biosynthesis appeared to be during myelination. We also found that ?-GlcChol and ?-GalChol are secreted from neurons and glial cells in association with exosomes. In vitro enzyme assays confirmed that GBA1 and GBA2 have transgalactosylation activity to transfer the galactose residue from GalCer to cholesterol to form ?-GalChol. This is the first report of the existence of ?-GalChol in vertebrates and how ?-GlcChol and ?-GalChol are formed in the brain.Medical Biochemistr

Autism as a disorder of neural information processing: directions for research and targets for therapy

The broad variation in phenotypes and severities within autism spectrum disorders suggests the involvement of multiple predisposing factors, interacting in complex ways with normal developmental courses and gradients. Identification of these factors, and the common developmental path into which theyfeed, is hampered bythe large degrees of convergence from causal factors to altered brain development, and divergence from abnormal brain development into altered cognition and behaviour. Genetic, neurochemical, neuroimaging and behavioural findings on autism, as well as studies of normal development and of genetic syndromes that share symptoms with autism, offer hypotheses as to the nature of causal factors and their possible effects on the structure and dynamics of neural systems. Such alterations in neural properties may in turn perturb activity-dependent development, giving rise to a complex behavioural syndrome many steps removed from the root causes. Animal models based on genetic, neurochemical, neurophysiological, and behavioural manipulations offer the possibility of exploring these developmental processes in detail, as do human studies addressing endophenotypes beyond the diagnosis itself

The 14-3-3ζ Protein Binds to the Cell Adhesion Molecule L1, Promotes L1 Phosphorylation by CKII and Influences L1-Dependent Neurite Outgrowth

BACKGROUND: The cell adhesion molecule L1 is crucial for mammalian nervous system development. L1 acts as a mediator of signaling events through its intracellular domain, which comprises a putative binding site for 14-3-3 proteins. These regulators of diverse cellular processes are abundant in the brain and preferentially expressed by neurons. In this study, we investigated whether L1 interacts with 14-3-3 proteins, how this interaction is mediated, and whether 14-3-3 proteins influence the function of L1. METHODOLOGY/PRINCIPAL FINDINGS: By immunoprecipitation, we demonstrated that 14-3-3 proteins are associated with L1 in mouse brain. The site of 14-3-3 interaction in the L1 intracellular domain (L1ICD), which was identified by site-directed mutagenesis and direct binding assays, is phosphorylated by casein kinase II (CKII), and CKII phosphorylation of the L1ICD enhances binding of the 14-3-3 zeta isoform (14-3-3ζ). Interestingly, in an in vitro phosphorylation assay, 14-3-3ζ promoted CKII-dependent phosphorylation of the L1ICD. Given that L1 phosphorylation by CKII has been implicated in L1-triggered axonal elongation, we investigated the influence of 14-3-3ζ on L1-dependent neurite outgrowth. We found that expression of a mutated form of 14-3-3ζ, which impairs interactions of 14-3-3ζ with its binding partners, stimulated neurite elongation from cultured rat hippocampal neurons, supporting a functional connection between L1 and 14-3-3ζ. CONCLUSIONS/SIGNIFICANCE: Our results suggest that 14-3-3ζ, a novel direct binding partner of the L1ICD, promotes L1 phosphorylation by CKII in the central nervous system, and regulates neurite outgrowth, an important biological process triggered by L1

Fluorescence in situ hybridisation analysis of chromosomal aberrations in gastric tissue: the potential involvement of Helicobacter pylori

In this series of experiments, a novel protocol was developed whereby gastric cells were collected using endoscopic cytology brush techniques, and prepared, such that interphase fluorescence in situ hybridization (FISH) could be performed. In total, 80 distinct histological samples from 37 patients were studied using four chromosome probes (over 32 000 cells analysed). Studies have previously identified abnormalities of these four chromosomes in upper GI tumours. Using premalignant tissues, we aimed to determine how early in Correa's pathway to gastric cancer these chromosome abnormalities occurred. Aneuploidy of chromosomes 4, 8, 20 and 17(p53) was detected in histologically normal gastric mucosa, as well as in gastritis, intestinal metaplasia, dysplasia and cancer samples. The levels of aneuploidy increased as disease severity increased. Amplification of chromosome 4 and chromosome 20, and deletion of chromosome 17(p53) were the more common findings. Hence, a role for these abnormalities may exist in the initiation of, and the progression to, gastric cancer. Helicobactor pylori infection was determined in premalignant tissue using histological analysis and PCR technology. Detection rates were comparable. PCR was used to subtype H. pylori for CagA status. The amplification of chromosome 4 in gastric tissue was significantly more prevalent in H. pylori-positive patients (n=7) compared to H. pylori-negative patients (n=11), possibly reflecting a role for chromosome 4 amplification in H. pylori-induced gastric cancer. The more virulent CagA strain of H. pylori was associated with increased disease pathology and chromosomal abnormalities, although numbers were small (CagA+ n=3, CagA− n=4). Finally, in vitro work demonstrated that the aneuploidy induced in a human cell line after exposure to the reactive oxygen species (ROS) hydrogen peroxide was similar to that already shown in the gastric cancer pathway, and may further strengthen the hypothesis that H. pylori causes gastric cancer progression via an ROS-mediated mechanism

NGF Causes TrkA to Specifically Attract Microtubules to Lipid Rafts

Membrane protein sorting is mediated by interactions between proteins and lipids. One mechanism that contributes to sorting involves patches of lipids, termed lipid rafts, which are different from their surroundings in lipid and protein composition. Although the nerve growth factor (NGF) receptors, TrkA and p75NTR collaborate with each other at the plasma membrane to bind NGF, these two receptors are endocytosed separately and activate different cellular responses. We hypothesized that receptor localization in membrane rafts may play a role in endocytic sorting. TrkA and p75NTR both reside in detergent-resistant membranes (DRMs), yet they responded differently to a variety of conditions. The ganglioside, GM1, caused increased association of NGF, TrkA, and microtubules with DRMs, but a decrease in p75NTR. When microtubules were induced to polymerize and attach to DRMs by in vitro reactions, TrkA, but not p75NTR, was bound to microtubules in DRMs and in a detergent-resistant endosomal fraction. NGF enhanced the interaction between TrkA and microtubules in DRMs, yet tyrosine phosphorylated TrkA was entirely absent in DRMs under conditions where activated TrkA was detected in detergent-sensitive membranes and endosomes. These data indicate that TrkA and p75NTR partition into membrane rafts by different mechanisms, and that the fraction of TrkA that associates with DRMs is internalized but does not directly form signaling endosomes. Rather, by attracting microtubules to lipid rafts, TrkA may mediate other processes such as axon guidance

Full-Length L1CAM and Not Its Δ2Δ27 Splice Variant Promotes Metastasis through Induction of Gelatinase Expression

Tumour-specific splicing is known to contribute to cancer progression. In the case of the L1 cell adhesion molecule (L1CAM), which is expressed in many human tumours and often linked to bad prognosis, alternative splicing results in a full-length form (FL-L1CAM) and a splice variant lacking exons 2 and 27 (SV-L1CAM). It has not been elucidated so far whether SV-L1CAM, classically considered as tumour-associated, or whether FL-L1CAM is the metastasis-promoting isoform. Here, we show that both variants were expressed in human ovarian carcinoma and that exposure of tumour cells to pro-metastatic factors led to an exclusive increase of FL-L1CAM expression. Selective overexpression of one isoform in different tumour cells revealed that only FL-L1CAM promoted experimental lung and/or liver metastasis in mice. In addition, metastasis formation upon up-regulation of FL-L1CAM correlated with increased invasive potential and elevated Matrix metalloproteinase (MMP)-2 and -9 expression and activity in vitro as well as enhanced gelatinolytic activity in vivo. In conclusion, we identified FL-L1CAM as the metastasis-promoting isoform, thereby exemplifying that high expression of a so-called tumour-associated variant, here SV-L1CAM, is not per se equivalent to a decisive role of this isoform in tumour progression

Mutations observed in mitochondrial DNA of salmon collected in Mano River, Fukushima Prefecture, Japan

On March 11, 2011, a great earthquake occurred off the east coast of Honshu Island, Japan. The consequent breakdown of the Fukushima Daiichi Nuclear Power Plant (FDNPP) caused a massive release of radionuclides into terrestrial and marine environments and into the atmosphere. The Abukuma Mountains region is one of the areas highly polluted by this accident. Freshwater fishes continued to live in this area after the FNPP accident became so polluted. Mitochondrial DNA (mtDNA) usually transfers from the mother to the next generation clonally. Therefore, it is one of the best genetic predictors of the effect of radiation on DNA. The influence of radiation can be presumed by comparing mtDNA between larval fish and their female parent. mtDNA of masu salmon was collected from an area highly polluted, namely, the upstream portion of Mano River, and compared it with that from nonpolluted cultured masu salmon. While no mutations were observed in the cultured masu salmon, those collected from Mano River exhibited three types of subdivisions in the Cytb region and two types of subdivisions in the D-loop region of mtDNA. These results suggest that exposure to radioactive cesium causes a base exchange in DNA. But the mutations observed were not serious enough to affect the masu salmon phenotype

Altered mRNA expression of genes related to nerve cell activity in the fracture callus of older rats: A randomized, controlled, microarray study

BACKGROUND: The time required for radiographic union following femoral fracture increases with age in both humans and rats for unknown reasons. Since abnormalities in fracture innervation will slow skeletal healing, we explored whether abnormal mRNA expression of genes related to nerve cell activity in the older rats was associated with the slowing of skeletal repair. METHODS: Simple, transverse, mid-shaft, femoral fractures with intramedullary rod fixation were induced in anaesthetized female Sprague-Dawley rats at 6, 26, and 52 weeks of age. At 0, 0.4, 1, 2, 4, and 6 weeks after fracture, a bony segment, one-third the length of the femur, centered on the fracture site, including the external callus, cortical bone, and marrow elements, was harvested. cRNA was prepared and hybridized to 54 Affymetrix U34A microarrays (3/age/time point). RESULTS: The mRNA levels of 62 genes related to neural function were affected by fracture. Of the total, 38 genes were altered by fracture to a similar extent at the three ages. In contrast, eight neural genes showed prolonged down-regulation in the older rats compared to the more rapid return to pre-fracture levels in younger rats. Seven genes were up-regulated by fracture more in the younger rats than in the older rats, while nine genes were up-regulated more in the older rats than in the younger. CONCLUSIONS: mRNA of 24 nerve-related genes responded differently to fracture in older rats compared to young rats. This differential expression may reflect altered cell function at the fracture site that may be causally related to the slowing of fracture healing with age or may be an effect of the delayed healing