Vestibular Loss and Balance Training Cause Similar Changes in Human Cerebral White Matter Fractional Anisotropy

Patients with bilateral vestibular loss suffer from severe balance deficits during normal everyday movements. Ballet dancers, figure skaters, or slackliners, in contrast, are extraordinarily well trained in maintaining balance for the extreme balance situations that they are exposed to. Both training and disease can lead to changes in the diffusion properties of white matter that are related to skill level or disease progression respectively. In this study, we used diffusion tensor imaging (DTI) to compare white matter diffusivity between these two study groups and their age- and sex-matched controls. We found that vestibular patients and balance-trained subjects show a reduction of fractional anisotropy in similar white matter tracts, due to a relative increase in radial diffusivity (perpendicular to the main diffusion direction). Reduced fractional anisotropy was not only found in sensory and motor areas, but in a widespread network including long-range connections, limbic and association pathways. The reduced fractional anisotropy did not correlate with any cognitive, disease-related or skill-related factors. The similarity in FA between the two study groups, together with the absence of a relationship between skill or disease factors and white matter changes, suggests a common mechanism for these white matter differences. We propose that both study groups must exert increased effort to meet their respective usual balance requirements. Since balance training has been shown to effectively reduce the symptoms of vestibular failure, the changes in white matter shown here may represent a neuronal mechanism for rehabilitation.     

Heterologous expression of the mammalian sodium-nucleobase transporter rSNBT1 in Leishmania tarentolae

Recombinant expression systems for mammalian membrane transport proteins are often limited by insufficient yields to support structural studies, inadequate post-translational processing and problems related with improper membrane targeting or cytotoxicity. Use of alternative expression systems and optimization of expression/purification protocols are constantly needed. In this work, we explore the applicability of the laboratory strain LEXSY of the ancient eukaryotic microorganism Leishmania tarentolae as a new expression system for mammalian nucleobase permeases of the NAT/NCS2 (Nucleobase-Ascorbate Transporter/Nucleobase-Cation Symporter-2) family. We achieved the heterologous expression of the purine-pyrimidine permease rSNBT1 from Rattus norvegicus (tagged at C-terminus with a red fluorescent protein), as confirmed by confocal microscopy and biochemical analysis of the subcellular fractions enriched in membrane proteins. The cDNA of rSNBT1 has been subcloned in a pLEXSY-sat-mrfp1vector and used to generate transgenic L. tarentolae-rsnbt1-mrfp1 strains carrying the pLEXSY-sat-rsnbt1-mrfp1 plasmid either episomally or integrated in the chromosomal DNA. The chimeric transporter rSNBT1-mRFP1 is targeted to the ER and the plasma membrane of the L. tarentolae promastigotes. The transgenic strains are capable of transporting nucleobases that are substrates of rSNBT1 but also of the endogenous L. tarentolae nucleoside/nucleobase transporters. A dipyridamole-resistant Na⁺-dependent fraction of uptake is attributed to the exogenously expressed rSNBT1.     

Improved Performance and Stability of Inverted Organic Solar Cells with Sol–Gel Processed,Amorphous Mixed Metal Oxide Electron Extraction Layers Comprising Alkaline Earth Metals

Stability of organic photovoltaic devices (OPVs) is a limiting factor for their commercialization and still remains a major challenge whilst power conversion efficiencies are now approaching minimum requirements. The inverted organic solar cell (iOSC) architecture shows promising potential for improving significantly the cell's working lifetime. However, when solution processed ZnO is used as electron extraction layer, an undesirable light‐soaking step is commonly required before the device reaches a non‐permanent maximum performance. This work investigates the use of Sr and Ba doped ZnO films, ZnSrO and ZnBaO, formed by sol‐gel deposition using molecular alkoxide precursor solutions, as electron extraction layers in a model iOSCs with poly [3‐hexylthiophene] (P3HT): [6, 6]‐phenyl C60 butyl acid methyl ester (PCBM) as the active layer. We show that using these ternary oxides the light‐soaking step can be circumvented by preventing a dipole forming between the oxide and the active organic layer as supported by electroabsorption spectroscopy measurements of the device built‐in field. It is suggested that Sr or Ba doping results in suppression/reduction of the oxygen adsorption at mobile oxygen vacancy sites on the metal oxide surface. Like in thin film transistor (TFT) applications, where materials like InGaZnO are rapidly becoming an important technology, the use of amorphous, mixed metal oxides allows improving the performance and stability of interfacial charge extraction layers for organic solar cells.     

Molecular Analysis of the Coat Protein of Potato virus Y Isolates in Greece Suggests Multiple Introduction from Different Genetic Pools

The phylogenetic relationships among Potato virus Y (PVY) isolates from northern and southern Greece were investigated. A large part of coat protein gene of 49 tobacco isolates and three from pepper was examined. The analysis showed that all 52 isolates consisted of 34 distinct haplotypes, with only one haplotype found in both northern and southern regions. The southern population was more diverse than that from the north. The phylogenetic analyses of the Greek haplotypes alone or in combination with isolates from other countries using the maximum likelihood method classified unambiguously almost all the haplotypes examined. Nine tobacco haplotypes from the south were classified as C‐like (particularly C1), whereas 22 haplotypes from tobacco and two from pepper from both north and south were classified as N‐like. One tobacco haplotype from the south was found recombinant between N‐like and C1 lineages. The pattern of molecular evolution was examined using the fixed‐effects likelihood and the single‐likelihood ancestor counting methods. The analysis indicated that the evolution of PVY isolates appeared to be conservative (purifying selection and neutral evolution). These findings are discussed in relation to the introduction of PVY in the tobacco crop in Greece and the between region dispersal. A scenario of multiple introductions of PVY isolates in north and south Greece from different genetic pools and low or nil between region spread of the virus isolates was proposed.     

Intracerebroventricular infusion of neuropeptide Y increases glucose dependent-insulinotropic peptide secretion in the fasting conscious dog

The rapid increase of incretins glucose-dependent insulinotropic peptide (GIP) and glucagon like peptide-1 (GLP-1), within 5-15 min, after food ingestion, suggests that a neural mechanism might be involved in the regulation of their secretion. The aim of this study is to determine whether intracerebroventricular (i.c.v) administration of neuropeptide Y (NPY), a widely distributed neurotransmmiter, can mediate this neural regulation of GIP secretion after food consumption. Six healthy mongrel dogs were utilized for this study. A prototype epicranial apparatus was placed surgically, allowing easy and exact localization of the third ventricle for infusions or sampling. Simultaneous blood sampling was obtained from cannulation of a hind limb vein. Plasma insulin, and GIP concentrations were measured after i.c.v infusion of 5, 10 and 25 microg of NPY dissolved in 0.5 ml of artificial cerebrospinal fluid (a CSF). The secretion of GIP and insulin were increased after the injection of NPY in a different pattern. Our data indicate that NPY might be involved in a possible neural control mechanism of GIP secretion after food consumption.