Axonal outgrowth is associated with increased ERK 1/2 activation but decreased caspase 3 linked cell death in Schwann cells after immediate nerve repair in rats

Background  

Extracellular-signal regulated kinase (ERK1/2) is activated by nerve damage and its activation precedes survival and proliferation of Schwann cells. In contrast, activation of caspase 3, a cysteine protease, is considered as a marker for apoptosis in Schwann cells. In the present study, axonal outgrowth, activation of ERK1/2 by phosphorylation (p-ERK 1/2) and immunoreactivity of cleaved caspase 3 were examined after immediate, delayed, or no repair of transected rat sciatic nerves.     

Formation of leptofibrils is associated with remodelling of muscle cells and myofibrillogenesis in the border zone of myocardial infarction

Leptofibrils, or leptomeres, remain the least studied cytoskeletal structures in muscle cells, and their function and mechanism of assembly are still poorly understood. Our ultrastructural study of the surviving cardiac myocytes located in the perinecrotic border zone of the infarcted left ventricle in rats revealed intense formation of leptofibrils and leptofibrillar clusters during 4-15 days following experimental myocardial infarction. In the perinecrotic myocytes, leptofibrils developed predominantly in the subsarcolemmal areas, near disassembled intercalated discs and at the sites of intense myofibrillogenesis in the peripheral zones of the sarcoplasm. We found that the development of these structures occurred before or at the time of assembly of myofibrils. In our material, leptofibrils consisted of longitudinally oriented filamentous bundles inserted in electron dense Z-band-like material and periodically crossed by 3-8 bands of this material with the period of cross-striation of 120-210 nm. The presence of leptofibrils in growing cytoplasmic processes and ruffles developing in the border zone in the areas of lost intercellular contacts indicates their formation de novo during post-infarction period. We observed four major morphological types of localization of these structures: (1) direct contact of one end of leptofibrils with Z bands of nascent, mature or disassembling myofibrils; (2) direct contact with the sarcolemma: (a) multifocal attachment of leptofibrils to the sarcolemma through the lateral surfaces of their minute Z band-like structures; (b) attachment of one or both ends of leptofibrils to the sarcolemma without contacts or in contact with myofibrils; (3) attachment of leptofibrils to subsarcolemmal accumulations of electron dense Z-band material in newly formed fasciae adherentes of the remodeled intercalated disks; (4) clustering and contacts of leptofibrils with one another predominantly at the level of their Z bands. Interestingly, most leptofibrils of all four types were topographically associated with the system of T-tubules, the sarcoplasmic reticulum and subsarcolemmal vesicles. Serial sections through the areas containing leptofibrils indicate their spindle-like or nearly cylindrical shape. Thus, we found that leptofibrils assemble in terminally differentiated cardiac myocytes following destabilization of their differentiated state and partial dedifferentiation induced by myocardial infarction. The results of this study demonstrate that formation of leptofibrils, earlier described mainly in the developing and malignant muscle, is temporally associated with adaptive structural remodelling and the activation of myofibrillogenesis in functionally overloaded cardiac myocytes of adult animals. Our findings suggest that re-expression of some structural characteristics of the embryonic muscle appear to represent one of the mechanisms that underlie adaptive plasticity of the myocardium following injury and under conditions of hyperfunction.     

Atypical perceptual narrowing in prematurely born infants is associated with compromised language acquisition at 2 years of age

Background

Protein aggregation plays important roles in several neurodegenerative disorders. For instance, insoluble aggregates of phosphorylated tau and of Aβ peptides are cornerstones in the pathology of Alzheimer's disease. Soluble protein aggregates are therefore potential diagnostic and prognostic biomarkers for their cognate disorders. Detection of the aggregated species requires sensitive tools that efficiently discriminate them from monomers of the same proteins. Here we have established a proximity ligation assay (PLA) for specific and sensitive detection of Aβ protofibrils via simultaneous recognition of three identical determinants present in the aggregates. PLA is a versatile technology in which the requirement for multiple target recognitions is combined with the ability to translate signals from detected target molecules to amplifiable DNA strands, providing very high specificity and sensitivity.

Results

For specific detection of Aβ protofibrils we have used a monoclonal antibody, mAb158, selective for Aβ protofibrils in a modified PLA, where the same monoclonal antibody was used for the three classes of affinity reagents required in the assay. These reagents were used for detection of soluble Aβ aggregates in solid-phase reactions, allowing detection of just 0.1 pg/ml Aβ protofibrils, and with a dynamic range greater than six orders of magnitude. Compared to a sandwich ELISA setup of the same antibody the PLA increases the sensitivity of the Aβ protofibril detection by up to 25-fold. The assay was used to measure soluble Aβ aggregates in brain homogenates from mice transgenic for a human allele predisposing to Aβ aggregation.

Conclusions

The proximity ligation assay is a versatile analytical technology for proteins, which can provide highly sensitive and specific detection of Aβ aggregates - and by implication other protein aggregates of relevance in Alzheimer's disease and other neurodegenerative disorders.     

The ABCG2 transporter is a key molecular determinant of the efficacy of sonodynamic therapy with Photofrin in glioma stem-like cells

We aimed to investigate the role of the ABCG2 transporter in the efficacy of sonodynamic therapy (SDT) with Photofrin in the glioma stem-like cells (GSCs) isolated and cultured from U251 glioma cells. Immunocytochemistry and flow cytometry analyses showed that ABCG2 was overexpressed in GSCs, and the percentage of ABCG2-positive GSCs was approximately 100%. The effect of ABCG2 on Photofrin extrusion in the absence or presence of a specific inhibitor of ABCG2 (fumitremorgin C; FTC) was investigated by determining the intracellular concentration of Photofrin in GSCs incubated with 20 μg/ml Photofrin. Extrusion of Photofrin by ABCG2 was inhibited by 10 μM FTC, which significantly increased the intracellular Photofrin concentration (p < 0.05) from 0.32 ± 0.11 μg/10⁶ cells to 0.89 ± 0.13 μg/10⁶ cells. MTT and TUNEL assays showed that the antitumor effect of SDT (incubation of GSCs with 20 μg/ml Photofrin for 6 h in the dark and ultrasonic activation at 1.0 MHz and 0.5 W/cm² for 2 min) was significantly improved by FTC pretreatment (p < 0.05). Moreover, incubation of GSCs with FTC significantly increased the relative production of ROS in response to SDT. The overexpression of ABCG2 in GSCs results in efflux of Photofrin, indicating that the antitumor effect of SDT with Photofrin may be reduced in GSCs overexpressing ABCG2. However, since FTC improves the efficacy of SDT in GSCs by inhibiting ABCG2-mediated efflux of Photofrin, FTC may be useful in SDT treatment of ABCG2-expressing cancer cells.     

An approach to MgCl2 activation on CdSe thin films for solar cells

The energy demand of the world is rapidly increasing and to cater this, there is a need to explore new renewable energy resources. CdSe thin film solar cells may be promising alternative to the CdTe solar cells which are extensively studied and used in solar cell technology. The pre/post deposition chlorine based treatments (viz. CdCl₂, MgCl₂, NH₄Cl) are the important steps to enhance the performance of Cd-based thin film solar cells. Therefore, a study on MgCl₂ activation treatment to CdSe thin films for solar cell applications as absorber layer is undertaken. Different physical properties of e-beam evaporated CdSe films (thickness 550 nm) grown on glass and ITO substrates are investigated and found to be strongly dependent on the post-chlorine treatment. The films have cubic zinc-blende structure and phase transformation from cubic (111) to hexagonal (002) is achieved with the MgCl₂ treatment while the optical band gap is reduced. I-V characteristics reveal the linear relation between voltage and current as well as the surface roughness is varied with treatment and improved homogeneity. The deposition of CdSe thin films is confirmed by elemental analysis where Cd and Se were found to be rich with treatment. The investigated results suggest that CdSe thin films treated by MgCl₂ and annealed at 320 °C may be a viable alternative absorber layer to the Cd-based solar cells.     

A parametric study of freezing injury in BPH1CAFTD-2 human prostate tumor cells

Freeze injury in BPH1(CAFTD)-2 cells frozen/thawed in suspension was studied through a two-level four-parameter (2(4)) experimental design and analysis. The four parameters considered were end temperature, hold time, TNFalpha concentration, and thawing rate. Thermal parameter values chosen were based on the approximate thermal history cells would experience in the peripheral region of a cryosurgical iceball. Cell suspensions were frozen at a constant 10 degree C/min on a directional solidification stage and viability was assessed within 1 hr post-thaw using a dye exclusion assay. The parameters affecting cell survival were determined through calculation of the individual parameter effects (E) and interactions (I) according to factorial design guidelines; data set curvature (C) was also determined. Cell viability ranged from a maximum of 87.6 percent to a minimum of 17.6 percent indicating trends in cell survival were sensitive to the parameters chosen. Survival was affected by the following parameters in order: lowering the end temperature, increasing the hold time, adding TNFalpha, and reducing the thawing rate. In addition, all 2-way parameter interactions except TNFalpha hold time were statistically significant. Curvature analysis showed that cell viability at the midpoint of the data was nearly 20 percent lower than predicted based on linear interpolation. These results were verified and extended using analysis of variance (ANOVA). We conclude that cryoinjury in this tumor line can be influenced by multiple interacting thermal parameters, most importantly end-temperature and hold time, as well as the presence of the cytokine TNFalpha. Finally, although the cell type is tumorigenic results suggest the possibility of using freezing to control benign prostatic hyperplasia (BPH) in addition to cancer within the prostate.     

Enhancement of object detection with transcranial direct current stimulation is associated with increased attention

ABSTRACT: BACKGROUND: We previously found that transcranial Direct Current Stimulation (tDCS) improves learning and performance in a task where subjects learn to detect potential threats indicated by small target objects hidden in a complex virtual environment. In the present study, we examined the hypothesis that these effects on learning and performance are related to changes in attention. The effects of tDCS were tested for three forms of attention (alerting, orienting, and executive attention) using the Attention Network Task (ANT), which were compared with performance on the object-learning task. RESULTS: Participants received either 0.1 mA (N = 10) or 2.0 mA (N = 9) tDCS during training and were tested for performance in object-identification before training (baseline-test) and again immediately after training (immediate test). Participants next performed the Attention Networks Task (ANT), and were later tested for object-identification performance a final time (delayed test). Alerting, but not orienting or executive attention, was significantly higher for participants receiving 2.0 mA compared with 0.1 mA tDCS (p < 0.02). Furthermore, alerting scores were significantly correlated with the proportion of hits (p < 0.01) for participants receiving 2.0 mA. CONCLUSIONS: These results indicate that tDCS enhancement of performance in this task may be related in part to the enhancement of alerting attention, which may benefit the initial identification, learning and/or subsequent recognition of target objects indicating potential threats.     

Abnormal auditory mismatch response in tinnitus sufferers with high-frequency hearing loss is associated with subjective distress level

Background  

Tinnitus is an auditory sensation frequently following hearing loss. After cochlear injury, deafferented neurons become sensitive to neighbouring intact edge-frequencies, guiding an enhanced central representation of these frequencies. As psychoacoustical data [1–3] indicate enhanced frequency discrimination ability for edge-frequencies that may be related to a reorganization within the auditory cortex, the aim of the present study was twofold: 1) to search for abnormal auditory mismatch responses in tinnitus sufferers and 2) relate these to subjective indicators of tinnitus.     

Nil-instantons associated with the classical torus CP 2 model

Finite energy solutions of the classical torus C P ² model are associated with certain analytic maps W C ³ where W is compact three-dimensional nilmanifold.     

Evidence for two energy levels associated with EL2 trap in GaAs

By photocapacitance technique, applied to n-type LEC-grown GaAs, two energy levels:E _v +0.45 eV andE _c –0.75 eV are identified, for the first time, as being associated with the EL2 trap. As follows from the analysis of photo-EPR results on highly resistive GaAs crystals, the same energy levels can be attributed to the arsenic antisite defect, As_GA. In view of these findings, it is argued that the occupied EL2 level corresponds to the neutral charge state of As_Ga defect.     

Bone repair in rat mandible by rhBMP-2 associated with two carriers

This study evaluated the quantity and quality of newly formed bone, stimulated by rhBMP-2 in combination with monoolein or chitosan gel as carriers, in critical bone defects created in 36 Wistar rat mandibles. Two weeks after surgery, the animals were anesthetized with 37.5% urethane submitted to perfusion and the hemi-mandibles removed for histological and histomorphometrical analysis. The results showed that there was a statistical difference between groups of animals receiving or not rhBMP-2 (p<0.05). Newly formed bone was more intense in the occlusal region, followed by the basal and middle regions, respectively. Both carriers, monoolein and chitosan gels were adequate for defect filling and control of protein release.     

Hypothalamic FTO is associated with the regulation of energy intake not feeding reward

Background  

Polymorphism in the FTO gene is strongly associated with obesity, but little is known about the molecular bases of this relationship. We investigated whether hypothalamic FTO is involved in energy-dependent overconsumption of food. We determined FTO mRNA levels in rodent models of short- and long-term intake of palatable fat or sugar, deprivation, diet-induced increase in body weight, baseline preference for fat versus sugar as well as in same-weight animals differing in the inherent propensity to eat calories especially upon availability of diverse diets, using quantitative PCR. FTO gene expression was also studied in organotypic hypothalamic cultures treated with anorexigenic amino acid, leucine. In situ hybridization (ISH) was utilized to study FTO signal in reward- and hunger-related sites, colocalization with anorexigenic oxytocin, and c-Fos immunoreactivity in FTO cells at initiation and termination of a meal.     

Hadronic jets associated with a photon trigger

We consider, within Quantum Chromodynamics, the fragmentation function of a quark into a hadron and a photon. A simple analytic expression is given which is adequate for practical applications. A measurable quantity is proposed, which is independent of the hadronization process and tests the underlying dynamics.     

Coexistence of light and heavy carriers associated with superconductivity and antiferromagnetism in CeNi0.8Bi2 with a Bi square net

We found that the ZrCuSiAs-type crystal CeNi(0.8)Bi(2) with a layered structure composed of alternate stacking of [CeNi(x)Bi(1)](δ+) and Bi(2)(δ-) exhibits a superconductive transition at ～4 K. The conductivities, magnetic susceptibilities, and heat capacities measurements indicate the presence of two types of carriers with notable different masses, i.e., a light electron responsible for superconductivity and a heavy electron interacting with the Ce 4f electron. This observation suggests that 6p electrons of Bi(2) forming the square net and electrons in CeNi(x)Bi(1) layers primarily correspond to the light and heavy electrons, respectively.