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In this study the role of membrane-associated molecules involved in entorhinohippocampal pathfinding was examined. First outgrowth preferences of entorhinal neurites were analyzed on membrane carpets obtained from their proper target area, the hippocampus, and compared to preferences on control membranes from brain regions which do not receive afferent connections from the entorhinal cortex. On a substrate consisting of alternating lanes of hippocampal and control membranes, entorhinal neurites exhibited a strong tendency to grow on lanes of hippocampal membrane. These tissue-specific outgrowth preferences were maintained even on membrane preparations from adult brain tissue devoid of myelin. To determine the possible maturation dependence of these membranes, we examined guidance preferences of entorhinal neurites on hippocampal membranes of different developmental stages ranging from embryonic to postnatal and adult. Given a choice between alternating lanes of embryonic (E15-E16) and neonatal (P0-P1) hippocampal membranes, entorhinal neurites preferred to extend on neonatal membranes. No outgrowth preferences were observed on membranes obtained between E19 and P10. From P10 onward there was a reoccurrence of a preference for postnatal membrane lanes when neurites were presented with a choice between P15, P30, and adult membranes (>P60). This choice behavior of entorhinal neurites temporally correlates with the ingrowth of the perforant path into the hippocampus and with the stabilization of this brain area in vivo. Experiments in which postnatal and adult hippocampal membranes were heat inactivated or treated to remove molecules sensitive to phosphatidylinositol-specific phospholipase C demonstrated that entorhinal fiber preferences were controlled in this assay by attractive guidance cues and were independent of phosphatidylinositol-sensitive linked molecules. Moreover, entorhinal neurites displayed a positive discrimination for membrane-associated guidance cues of their target field, thus preferring to grow on membranes from the molecular layer of the dentate gyrus compared with CA3 or hilus membranes. Heat-inactivation experiments indicated that preferential growth of entorhinal axons is due to a specific attractivity of the molecular layer substrate. The data presented demonstrate that outgrowth of entorhinal fibers on hippocampal membranes is target and maturation dependent. Key Words: pathfinding; development; entorhinohippocampal system; stripe assay.

In N1E-115 cells, neurite retraction induced by neurite remodelling factors such as lysophosphatidic acid, sphingosine 1-phosphate and semaphorin 3A require the activity of phosphatidylinositol 4-phosphate 5-kinases (PIP5Ks). PIP5Ks synthesise the phosphoinositide lipid second messenger phosphatidylinositol(4,5)bisphosphate [PtdIns(4,5)P2], and overexpression of active PIP5K is sufficient to induce neurite retraction in both N1E-115 cells and cerebellar granule neurones. However, how PIP5Ks are regulated or how they induce neurite retraction is not well defined. Here, we show that neurite retraction induced by PIP5Kβ is dependent on its interaction with the low molecular weight G protein Rac. We identified the interaction site between PIP5Kβ and Rac1 and generated a point mutant of PIP5Kβ that no longer interacts with endogenous Rac. Using this mutant, we show that Rac controls the plasma membrane localisation of PIP5Kβ and thereby the localised synthesis of PtdIns(4,5)P2 required to induce neurite retraction. Mutation of this residue in other PIP5K isoforms also attenuates their ability to induce neurite retraction and to localise at the membrane. To clarify how increased levels of PtdIns(4,5)P2 induce neurite retraction, we show that mutants of vinculin that are unable to interact with PtdIns(4,5)P2, attenuate PIP5K- and LPA-induced neurite retraction. Our findings support a role for PtdIns(4,5)P2 synthesis in the regulation of vinculin localisation at focal complexes and ultimately in the regulation of neurite dynamics. [ABSTRACT FROM AUTHOR]

Background Reduced systolic reserve on effort may be present in subjects with hypertension but no evidence of hypertensive cardiomyopathy. We assessed the determinants of abnormal cardiac performance during exercise in hypertensive patients without left ventricular hypertrophy. Materials and methods Thirty-five newly diagnosed, never-treated-earlier hypertensive patients without definite indication for left ventricular hypertrophy at echocardiography underwent radionuclide ambulatory monitoring of left ventricular function at rest and during upright bicycle exercise testing. Results The patients were classified into two groups according to their ejection fraction response to exercise. In 21 patients (group 1), the ejection fraction increased ≥ 5% with exercise and in 14 patients (group 2), the ejection fraction either increased < 5% or decreased with exercise. Patients of group 1 had lower peak filling rate at rest and less augmentation in end-diastolic volume during exercise (both P < 0·01) when compared with patients of group 2. A significant relationship between the magnitude of change in ejection fraction with exercise and both peak filling rate at rest ( r = 0·58, P < 0·01) and exercise-induced change in end-diastolic volume ( r = 0·45, P < 0·01) was found. Conclusions In newly diagnosed, never-treated-earlier hypertensive subjects with no evidence of hypertensive cardiomyopathy, the cardiac response to exercise is dependent on adequate diastolic filling volume to maintain systolic performance. [ABSTRACT FROM AUTHOR]

The paper deals with the identification of plasma equilibrium reconstruction in D-shaped tokamaks on the base of plasma external magnetic measurements. The methods of such identification are directed to increase their speed of response when plasma discharges are relatively short, like in the spherical Globus-M2 tokamak (Ioffe Inst., St. Petersburg, Russia). The new approach is first to apply to the plasma discharges data the off-line equilibrium reconstruction algorithm based on the Picard iterations, and obtain the gaps between the plasma boundary and the first wall, and the second is to apply new identification methods to the gap values, producing plasma shape models operating in real time. The inputs for on-line robust identification algorithms are the measurements of magnetic fluxes on magnetic loops, plasma current, and currents in the poloidal field coils measured by the Rogowski loops. The novel on-line high-performance identification algorithms are designed on the base of (i) full-order observer synthesized by linear matrix inequality (LMI) methodology, (ii) static matrix obtained by the least square technique, and (iii) deep neural network. The robust observer is constructed on the base of the LPV plant models which have the novelty that the state vector contains the gaps which are estimated by the observer, using input and output signals. The results of the simulation of the identification systems on the base of experimental data of the Globus-M2 tokamak are presented. [ABSTRACT FROM AUTHOR]

Background Fatigability and dyspnoea on effort are present in many patients with Fabry's disease. We assessed the determinants of cardiac performance during exercise in patients with Fabry's disease and preserved left ventricular ejection fraction at rest. Materials and methods Sixteen patients with Fabry's disease and 16 control subjects underwent radionuclide angiography at rest and during exercise, tissue Doppler echocardiography and magnetic resonance imaging at rest. Results The exercise-induced change in stroke volume was +25 ± 14% in controls and +5·8 ± 19% in patients with Fabry's disease ( P < 0·001). In 10 patients (group 1), the stroke volume increased (+19 ± 10%), and in 6 patients (group 2) it decreased (–16 ± 9%) with exercise. Patients of group 2 were older, had worse renal function, higher left ventricular mass and impaired diastolic function compared to group 1. The abnormal stroke volume response to exercise in group 2 was associated with a decrease in end-diastolic volume ( P < 0·001) and a lack of reduction of end-systolic volume ( P < 0·01) compared with both controls and group 1. The ratio of peak early-diastolic velocity from mitral filling to peak early-diastolic mitral annulus velocity was the only independent predictor of exercise-induced change in stroke volume (B –0·44; SE 0·119; β–0·70; P < 0·005). Conclusions The majority of patients with Fabry's disease were able to augment stroke volume during exercise by increasing end-diastolic volume, whereas patients with more advanced cardiac involvement may experience the inability to increase cardiac output by the Frank Starling mechanism. [ABSTRACT FROM AUTHOR]

Neurodegeneration and brain edema are hallmarks of human malignant brain tumors. Here we show that genetic or pharmacological inhibition of the glutamate transporter xCT (Xc− system, encoded by SLC7a11) in vivo leads to abrogated neurodegeneration, attenuated perifocal edema and prolonged survival. These results show a crucial role for xCT in glioma-induced neurodegeneration and brain edema, corroborating the concept that edema formation may be in part a consequence of peritumoral cell death. [ABSTRACT FROM AUTHOR]

Selenium is present in various biologically important selenoproteins. The preferential incorporation of selenium into the brain indicates its significance for this organ, but so far knowledge concerning the cerebral selenoproteome is scarce. We therefore investigated the expression of selenoproteins in various regions of the rat brain, various subcellular fractions and several brain cell lines by 75Se-labelling, gel electrophoretic separation and autoradiography, with the 75Se tracer as the selenoprotein marker. Quantitative evaluation of the labelled proteins in selenium-deficient rats revealed information regarding preferentially supplied selenoproteins and their distribution; 21 selenoproteins could be distinguished, among them a novel or modified 15-kDa selenoprotein enriched in the cerebellum cytosol. The selenoproteins differed in the degree of their expression among the brain regions and within a region among the subcellular fractions. Some cell-type-specific selenium-containing proteins were found in the cell lines. Differences in the distribution patterns between mono-cultured and co-cultured endothelial cells and astrocytes showed that mediators produced by other cells could affect the selenoprotein expression of a specific cell-type. This effect might play a role in the uptake and distribution of selenium in the brain but could also be of significance in the selenium metabolism of other tissues. [ABSTRACT FROM AUTHOR]

Selenoproteins have been recognized as modulators of brain function and signaling. Phospholipid hydroperoxide glutathione peroxidase (GPx4/PHGPx) is a unique member of the selenium-dependent glutathione peroxidases in mammals with a pivotal role in brain development and function. GPx4 exists as a cytosolic, mitochondrial, and nuclear isoform derived from a single gene. In mice, the GPx4 gene is located on chromosome 10 in close proximity to a functional retrotransposome that is expressed under the control of captured regulatory elements. Elucidation of crystallographic data uncovered structural peculiarities of GPx4 that provide the molecular basis for its unique enzymatic properties and substrate specificity. Monomeric GPx4 is multifunctional: it acts as a reducing enzyme of peroxidized phospholipids and thiols and as a structural protein. Transcriptional regulation of the different GPx4 isoforms requires several isoform-specific cis-regulatory sequences and trans-activating factors. Cytosolic and mitochondrial GPx4 are the major isoforms exclusively expressed by neurons in the developing brain. In stark contrast, following brain trauma, GPx4 is specifically upregulated in non-neuronal cells, i.e., reactive astrocytes. Molecular approaches to genetic modification in mice have revealed an essential and isoform-specific function for GPx4 in development and disease. Here we review recent findings on GPx4 with emphasis on its molecular structure and function and consider potential mechanisms that underlie neural development and neuropathological conditions. [ABSTRACT FROM AUTHOR]

Abstract: Glutathione peroxidase-4 (GPx4) is a multifunctional selenoprotein expressed as mitochondrial, cytosolic, or nuclear isoforms. As a catalytically active enzyme it has been implicated in antioxidative defense, but during sperm development it functions as a structural protein. GPx4 null mice die in utero at midgestation and knockdown of GPx4 during embryogenesis disturbs brain development. To explore the cerebral function of GPx4 we profiled cell-specific enzyme expression at various stages of perinatal brain maturation and investigated its regulation following brain injury by immunohistochemistry, in situ hybridization, and quantitative RT-PCR. Large amounts of GPx4 mRNA were detected in all neuronal layers during perinatal brain development but expression became restricted during postnatal maturation. In adult brain mitochondrial and cytosolic GPx4 isoforms were detected in neurons of cerebral cortex, hippocampus, and cerebellum whereas glial cells were devoid of GPx4. Following selective brain injury expression of the enzyme was upregulated in reactive astrocytes of lesioned areas and deafferented regions but not in neurons. Selective knockdown of GPx4 by small interfering RNA induced depletion of phosphatidylinositol-(4,5)-bisphosphate in the neuronal plasma membrane and subsequently apoptosis as indicated by caspase-3 activation. We hypothesize that astrocytic upregulation of GPx4 in response to injury is part of a protective cascade counteracting further cell damage. [Copyright &y& Elsevier]

Oxidative brain damage, such as excitotoxicity and stroke, leads to primary neuronal destruction. The primary damage is further potentiated by macrophages and microglial cells, which are attracted and invade into the zone of damage resulting in secondary neuronal death. Since the essential trace element selenium has anti-inflammatory properties, we analyzed the effects of selenium on these inflammatory cells. Here, we show that the essential trace element selenium abrogates the stress-induced migration of microglial cells. Thus, the antimigratory effects of selenium may attenuate the secondary cell death cascade by preventing microglial invasion. [ABSTRACT FROM AUTHOR]

Within a recent study on the vibrissae motor performance after facial nerve repair in strains of blind (SD/RCS) and sighted (SD) rats we found that, despite persisting myotopic disorganization in the facial nucleus, the blind animals fully restored vibrissal whisking. Here we searched for morphological substrates of better recovery in the regenerating motoneurons and in the cerebral motor cortex. Expression analyses of the neurite growth-related proteins f-actin, neuronal class III β-tubulin and plasticity-related gene-1, and stereological estimates of growth cone densities revealed a more vigorous regenerative response in the proximal nerve stump of blind SD/RCS rats compared with SD animals at 5–7 days after buccal nerve transection. Using c-Fos immunoreactivity as a marker for neuronal activation, we found that the volume of the cortex acutely responding to nerve transection (facial muscles reactive volume, FMRV) in both hemispheres of intact sighted rats was twofold smaller than that measured in blind animals. One month after transection and suture of the right facial nerve (FFA) we found a twofold increase in the FMRV in both rat strains compared with intact animals. The FMRV in SD/RCS animals, but not in SD rats, returned to the values in intact rats 2 months after FFA. Our findings suggest that enhanced plasticity in the CNS and an augmented regenerative response of the injured motoneurons contribute to better functional recovery in blind rats. [ABSTRACT FROM AUTHOR]

Current treatment modalities for malignant gliomas do not allow long-term survival. Here, we identify suberoylanilide hydroxamic acid (SAHA), an inhibitor of histone deacetylases (HDAC), as an effective experimental anti-glioma agent. Administration of SAHA to various glioma cell lines obtained from human, rat and mouse inhibited tumour cell growth in a range of 1–10 μm. This anti-glioma property is associated with up-regulation of the cell cycle control protein p21/WAF, as well as the induction of apoptosis. A novel tumour invasion model using slice cultures of rat brain corroborated the anti-glioma properties of SAHA in the organotypic brain environment. In this model, glioma invasion compromised adjacent brain parenchyma, and this tumour-associated cytotoxicity could be inhibited by SAHA. In addition, a 10-fold dose escalation experiment did not challenge the viability of cultured brain slices.In vivo, a single intratumoural injection of SAHA 7 days after orthotopic implantation of glioma cells in syngeneic rats doubled their survival time. These observations identify chromatin-modifying enzymes as possible and promising targets for the pharmacotherapy of malignant gliomas. [ABSTRACT FROM AUTHOR]

Phospholipid-mediated signalling on neurons provokes diverse responses such as neurogenesis, pattern formation and neurite remodelling. We have recently uncovered a novel set of molecules in the mammalian brain, named plasticity-related genes (PRGs), which mediate lipid phosphate phosphatase activity and provide evidence for their involvement in mechanisms of neuronal plasticity. Here, we report on a new member of the vertebrate-specific PRG family, which we have named plasticity-related gene-3 (PRG-3). PRG-3 is heavily expressed in the brain and shows a specific expression pattern during brain development where PRG-3 expression is found predominantly in neuronal cell layers and is already expressed at embryonic day 16. In the mature brain, strongest PRG-3 expression occurs in the hippocampus and cerebellum. Overexcitation of neurons induced by kainic acid leads to a transient down-regulation of PRG-3. Furthermore, PRG-3 is expressed on neurite extensions and promotes neurite growth and a spreading-like cell body in neuronal cells and COS-7 cells. In contrast to previously described members of the PRG family, PRG-3 does not perform its function through enzymatic phospholipid degradation. In summary, our findings feature a new member of the PRG family which shows dynamic expression regulation during brain development and neuronal excitation. [ABSTRACT FROM AUTHOR]