Miracle-dz/UniFAR-FTUs huggingface dataset:
Axonal degeneration and regeneration: a mechanistic tug‐of‐war

Axonal degeneration is a common hallmark of both nerve injury and many neurodegenerative conditions, including motor neuron disease, glaucoma, and Parkinson’s, Alzheimer’s, and Huntington’s diseases. Degeneration of the axonal compartment is distinct from neuronal cell death, and often precedes or is associated with the appearance of the symptoms of the disease. A complementary process is the regeneration of the axon, which is commonly observed following nerve injury in many invertebrate neurons and in a number of vertebrate neurons of the PNS. Important discoveries, together with innovative imaging techniques, are now paving the way towards a better understanding of the dynamics and molecular mechanisms underlying these two processes. In this study, I will discuss these recent findings, focusing on the balance between axonal degeneration and regeneration.
A large mobility of hydrophilic molecules at the outmost layer controls the protein adsorption and adhering behavior with the actin fiber orientation of human umbilical vein endothelial cells (HUVEC)

Adhesion behaviors of human umbilical vein endothelial cells (HUVECs) are interestingly affected by the mobility of hydrophilic chains on the material surfaces. Surfaces with different molecular mobilities were prepared using ABA-type block copolymers consisting polyrotaxane (PRX) or poly(ethylene glycol) (PEG) central block (A block), and amphiphilic anchoring B blocks of poly(2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate) (PMB). Two different molecular mobilities of the PRX chains were designed by using normal α-cyclodextrin (α-CD) or α-CD whose hydroxyl groups were converted to methoxy groups in a given ratio to improve its molecular mobility (PRX–PMB and OMe-PRX–PMB). The surface mobility of these materials was assessed as the mobility factor (Mf), which is measured by quartz crystal microbalance with dissipation monitoring system. HUVECs adhered on OMe-PRX–PMB surface much more than PRX–PMB and PMB-block–PEG–block-PMB (PEG–PMB) surfaces. These different HUVEC adhesions were correlated with the density of cell-binding site of adsorbed fibronectin. In addition, the alignment of the actin cytoskeleton of adhered HUVECs was strongly suppressed on the PEG–PMB, PRX–PMB, and OMe-PRX–PMB in response to the increased Mf value. Remarkably, the HUVECs adhered on the OMe-PRX–PMB surface with much less actin organization. We concluded that not only the cell adhesion but also the cellular function are regulated by the molecular mobility of the outmost material surfaces.
Exchange‐mediated dilution of brain lactate specific activity: implications for the origin of glutamate dilution and the contributions of glutamine dilution and other pathways

The magnitude of metabolic activation is greatly underestimated in autoradiographic studies using [1‐ or 6‐14C]glucose compared to parallel assays with [14C]deoxyglucose indicating that most of the label corresponding to the additional [14C]glucose consumed during activation compared to rest is quickly released from activated structures. Label could be lost by net release of [14C]lactate from brain or via lactate exchange between blood and brain. These possibilities were distinguished by comparison of glucose and lactate specific activities in arterial blood and brain before, during, and after generalized sensory stimulation and during spreading cortical depression. Over a wide range of brain lactate concentrations, lactate specific activity was close to the theoretical maximum, i.e. half that of [6‐14C]glucose, indicating that exchange‐mediated dilution of lactate is negligible and that efflux of [14C]lactate probably accounts for most of the label loss. Low lactate dilution also indicates that dilution of glutamate C4 fractional enrichment in [13C]glucose studies, currently ascribed predominantly to lactate exchange, arises from other unidentified pathways or factors. Alternative explanations for glutamate dilution (presented in Supporting Information) include poorly labeled amino acid pools and oxidative metabolism of minor substrates in astrocytes to first dilute the astrocytic glutamine pool, followed by dilution of glutamate via glutamate–glutamine cycling.
Synthesis and characterization of a hybrid (chitosan-g-glycidyl methacrylate)–xanthan hydrogel

This work reports the synthesis and characterization of a new material obtained by mixing the hybrid natural–synthetic chitosan-g-glycidyl methacrylate (CTS–g–GMA) biopolymer and xanthan gum (X). All materials were characterized by infrared spectroscopy (FTIR), X-ray diffraction, and thermal analysis (DSC and TGA) and the results were contrasted with those of the precursor materials. The swelling index of the hydrogels decreases when the GMA mass percentage increases. The X-ray diffraction patterns show that the hybrid hydrogels are amorphous in contrast to chitosan (CTS), which is semi-crystalline. FTIR analysis confirms the existence of physical interactions among constituents. Rheological properties, η, G′, and G″, were determined as a function of flow allowing one to conclude that (CTS–g–GMA)–X behaves as physical hydrogel. Additionally, we report viability of fibroblasts when cultured onto the synthesized hydrogels. This study shows that these hydrogels support cell viability and have potential for use in biomedical engineering applications.
GABAergic striatal neurons exhibit caspase‐independent, mitochondrially mediated programmed cell death

GABAergic striatal neurons are compromised in basal ganglia pathologies and we analysed how insult nature determined their patterns of injury and recruitment of the intrinsic mitochondrial pathway during programmed cell death (PCD). Stressors affecting targets implicated in striatal neurodegeneration [3‐morpholinylsydnoneimine (SIN‐1), 3‐nitropropionic acid (3‐NP), NMDA, 3,5‐dihydroxyphenylglycine (DHPG), and staurosporine (STS)] were compared in cultured GABAergic neurons from murine striatum by analyzing the progression of injury and its correlation with mitochondrial involvement, the redistribution of intermembrane space (IMS) proteins, and patterns of protease activation. Stressors produced PCD exhibiting slow‐onset kinetics with time‐dependent annexin‐V labeling and eventual DNA fragmentation. IMS proteins including cytochrome c were differentially distributed, although stressors except STS produced early redistribution of apoptosis‐inducing factor and Omi, suggestive of early recruitment of both caspase‐dependent and caspase‐independent signaling. In general, Bax mobilization to mitochondria appeared to promote IMS protein redistribution. Caspase 3 activation was prominent after STS, whereas NMDA and SIN‐1 produced mainly calpain activation, and 3‐NP and DHPG elicited a mixed profile of protease activation. PCD and redistribution of IMS proteins in striatal GABAergic neurons were canonical and insult‐dependent, reflecting differential interplay between the caspase cascade and alternate cell death pathways.
Cellular calcium deficiency plays a role in neuronal death caused by proteasome inhibitors

Cytosolic Ca2+ concentration ([Ca2+]i) is reduced in cultured neurons undergoing neuronal death caused by inhibitors of the ubiquitin proteasome system. Activation of calcium entry via voltage‐gated Ca2+ channels restores cytosolic Ca2+ levels and reduces this neuronal death ( Snider et al. 2002 ). We now show that this reduction in [Ca2+]i is transient and occurs early in the cell death process, before activation of caspase 3. Agents that increase Ca2+ influx such as activation of voltage‐gated Ca2+ channels or stimulation of Ca2+ entry via the plasma membrane Na–Ca exchanger attenuate neuronal death only if applied early in the cell death process. Cultures treated with proteasome inhibitors had reduced current density for voltage‐gated Ca2+ channels and a less robust increase in [Ca2+]i after depolarization. Levels of endoplasmic reticulum Ca2+ were reduced and capacitative Ca2+ entry was impaired early in the cell death process. Mitochondrial Ca2+ was slightly increased. Preventing the transfer of Ca2+ from mitochondria to cytosol increased neuronal vulnerability to this death while blockade of mitochondrial Ca2+ uptake via the uniporter had no effect. Programmed cell death induced by proteasome inhibition may be caused in part by an early reduction in cytosolic and endoplasmic reticulum Ca2+, possibly mediated by dysfunction of voltage‐gated Ca2+ channels. These findings may have implications for the treatment of disorders associated with protein misfolding in which proteasome impairment and programmed cell death may occur.
Surface modification by grafting of poly(SBMA-co-AEMA)-g-PDA coating and its application in CE

In this paper, a novel copolymer consisting of sulfobetaine methacrylate (SBMA) and 2-aminoethyl methacrylate (AEMA) named as poly(SBMA-co-AEMA) was synthesized by conventional free-radical polymerization, the poly(SBMA-co-AEMA) zwitterionic copolymer was immobilized onto glass slides surface through polydopamine (PDA)-anchored coating and formed poly(SBMA-co-AEMA)-g-PDA coating. The defined copolymer was characterized by nuclear magnetic resonance hydrogen spectroscopy (1H NMR) and gel permeation chromatography. The surface morphology, thickness, and chemical component of poly(SBMA-co-AEMA)-g-PDA coating were studied by atom force microscope, ellipsometry, and X-ray photoelectron spectroscopy, respectively. The hydrophilicity and stability of these coatings were investigated by static water contact angles. And finally, the poly(SBMA-co-AEMA)-g-PDA coating was successfully applied into capillary inner surface for suppression electro-osmotic flow and protein separation by capillary electrophoresis.
Dynamic chromatin remodeling events in hippocampal neurons are associated with NMDA receptor‐mediated activation of Bdnf gene promoter 1

To determine the epigenetic events associated with NMDA receptor‐mediated activation of brain‐derived neurotrophic factor gene (Bdnf) promoter 1 by hippocampal neurons in culture, we screened 12 loci across 4.5 kb of genomic DNA 5′ of the transcription start site (TSS) of rat Bdnf for specific changes in histone modification and transcription factor binding following NMDA receptor stimulation. Chromatin immunoprecipitation (ChIP) assays showed that NMDA receptor stimulation produced a durable, time‐dependent decrease in histone H3 at lysine 9 dimethylation (H3K9me2), within 3 h after NMDA treatment across multiple loci. Concomitant increases in H3K4me2 and H3K9/14 acetylation (H3AcK9/14) were associated with transcriptional activation, but occurred at fewer sites within the promoter. The decrease in H3K9me2 was associated with release of HDAC1, MBD1, MeCP2, and REST from specific locations within promoter 1, although with different kinetics. In addition, occupancy of sites proximal to and distal to the TSS by the transcription factors NF‐κB, CREB‐binding protein (CBP), and cAMP‐response element‐binding protein were correlated with increased occupancy of RNA polymerase II at two loci proximal to the TSS following NMDA receptor stimulation. These temporal changes in promoter occupancy could occur thousands of base pairs 5′ of the TSS, suggesting a mechanism that produces waves of Bdnf transcription.
Involvement of multiple protein kinases in cPLA2 phosphorylation, arachidonic acid release, and cell death in in vivo and in vitro models of 1‐methyl‐4‐phenylpyridinium‐induced parkinsonism – the possible key role of PKG

The study was aimed at investigating in vivo and in vitro the involvement of the cGMP/cGMP‐dependent protein kinase (PKG) signaling pathway in MPP+‐induced cytosolic phospholipase A2 (cPLA2) activation of dopaminergic neurons. MPP+ activated neuronal nitric oxide synthase (NOS)/soluble guanylyl cyclase/cGMP pathway in mouse midbrain and striatum, and in pheochromocytoma cell line 12 cells, and caused an upward shift in [Ca2+]i level in the latter. The activation was accompanied by increases in total and phosphorylated cPLA2, and increased arachidonic acid release. Effects of selective inhibitors [2‐oxo‐1,1,1‐trifluoro‐6,9‐12,15‐heneicosatetraene (AACOCF3), (E)‐6‐(bromomethylene)tetrahydro‐3‐(1‐naphthalenyl)2h‐pyran‐2‐one (BEL)] indicated the main impact of cPLA2 on arachidonic acid release in pheochromocytoma cell line 12 cells. Treatment of the cells with the protein kinase inhibitors GF102610x, UO126, and KT5823, and with the nitric oxide synthase (NOS) inhibitor NNLA revealed the involvement of protein kinase C (PKC) and extracellular signal‐regulated kinases 1 and 2 (ERK 1/2), with the possible key role of PKG, in cPLA2 phosphorylation at Ser505. Inhibitors of cPLA2 and PKG increased viability and reduced MPP+‐induced apoptosis of the cells. Our results indicate that the neuronal NOS/cGMP/PKG pathway stimulates cPLA2 phosphorylation at Ser505 by activating PKC and ERK1/2, and suggest that up‐regulation of this pathway in experimental models of Parkinson’s disease may mediate dopaminergic neuron degeneration and death through activation of cPLA2.
Electrospinning of gelatin for tissue engineering – molecular conformation as one of the overlooked problems

Gelatin is one of the most promising materials in tissue engineering as a scaffold component. This biopolymer indicates biocompatibility and bioactivity caused by the existence of specific amino acid sequences, being preferred sites for interactions with cells, with high similarity to natural extracellular matrix. The present paper does not aspire to be a full review of electrospinning of gelatin and gelatin containing nanofibers as scaffolds in tissue engineering. It is focused on the still open question of the role of the higher order structures of gelatin in scaffold’s bioactivity/functionality. Gelatin molecules can adopt various conformations depending on temperature, solvent, pH, etc. Our review indicates the potential ways for formation of α-helix conformation during electrospinning and the methods of further structure stabilization. It is intuitively expected that the native α-helix conformation appearing as a result of partial renaturation of gelatin can be beneficial from the viewpoint of bioactivity of scaffolds, providing thus a much cheaper alternative approach as opposed to expensive electrospinning of native collagen.
Real‐time visualization of cytoplasmic calpain activation and calcium deregulation in acute glutamate excitotoxicity

Although calpain (EC 3.4.22) protease activation was suggested to contribute to excitotoxic delayed calcium deregulation (DCD) via proteolysis of Na+/Ca2+ exchanger 3 (NCX3), cytoplasmic calpain activation in relation to DCD has never been visualized in real‐time. We employed a calpain fluorescence resonance energy transfer substrate to simultaneously image calpain activation and calcium deregulation in live cortical neurons. A calpain inhibitor‐sensitive decline in fluorescence resonance energy transfer was observed at 39 ± 5 min after the occurrence of DCD in neurons exposed to continuous glutamate (100 μM). Inhibition of calpain by calpeptin did not delay the onset of DCD, recovery from DCD‐like reversible calcium elevations, or cell death despite inhibiting α‐spectrin processing by > 90%. NCXs reversed during glutamate exposure, the NCX antagonist KB‐R7943 prolonged the time to DCD, and significant NCX3 cleavage following 90 min of glutamate exposure was not observed. Our findings suggest that robust calpain activation associated with acute glutamate toxicity occurs only after a sustained loss in calcium homeostasis. Processing of NCX3 or other calpain substrates is unlikely to be the primary cause of acute excitotoxicity in cortical neurons. However, a role for calpain as a contributing factor or in response to milder glutamate insults is not excluded.
Protein kinase C epsilon activation delays neuronal depolarization during cardiac arrest in the euthermic arctic ground squirrel

During the pre‐hibernation season, arctic ground squirrels (AGS) can tolerate 8 min of asphyxial cardiac arrest (CA) without detectable brain pathology. Better understanding of the mechanisms regulating innate ischemia tolerance in AGS has the potential to facilitate the development of novel prophylactic agents to induce ischemic tolerance in patients at risk of stroke or CA. We hypothesized that neuroprotection in AGS involves robust maintenance of ion homeostasis similar to anoxia‐tolerant turtles. Ion homeostasis was assessed by monitoring ischemic depolarization (ID) in cerebral cortex during CA in vivo and during oxygen glucose deprivation in vitro in acutely prepared hippocampal slices. In both models, the onset of ID was significantly delayed in AGS compared with rats. The epsilon protein kinase C (εPKC) is a key mediator of neuroprotection and inhibits both Na+/K+‐ATPase and voltage‐gated sodium channels, primary mediators of the collapse of ion homeostasis during ischemia. The selective peptide inhibitor of εPKC (εV1‐2) shortened the time to ID in brain slices from AGS but not in rats despite evidence that εV1‐2 decreased activation of εPKC in brain slices from both rats and AGS. These results support the hypothesis that εPKC activation delays the collapse of ion homeostasis during ischemia in AGS.
Synthesis of poly(glutamic acid)-tyramine hydrogel by enzyme-mediated gelation for controlled release of proteins

An in situ-formed hydrogel was synthesized by enzymatic cross-linking of poly(γ-glutamic acid)–tyramine conjugates (PGA–Tyr) using horseradish peroxidase (HRP) and hydrogen peroxide (H2O2). The gelation time ranged from 25 s to 5 min was accomplished by tuning the concentration of HRP, H2O2/Tyr molar ratio and the degree of substitution (DS) of Tyr groups. The storage modulus (G′), cross-link density, and mesh size can be tailored by controlling the H2O2/Tyr ratio and DS. The rheological analysis indicated that the storage modulus (G′) can be tailored from approximately 40 to over 1100 Pa with the increasing H2O2/Tyr ratio and DS. The bovine serum albumin (BSA) was used as model protein and encapsulated into the hydrogel during the enzyme-mediated cross-linking reaction. Controlled release of BSA in vitro from the PGA–Tyr hydrogel was obtained. The release rate and cumulative release amount of encapsulated BSA were manipulated by controlling the H2O2/Tyr ratio and DS. More than 90% of encapsulated BSA was released from the hydrogel with low cross-link density and lager mesh size in 60 h, while only 68% of BSA was released from the hydrogel with high cross-link density and small mesh size. The results indicated that the PGA–Tyr hydrogel is a promising material for the controlled release of therapeutic protein or peptides.
Oxidized phosphatidylcholine formation and action in oligodendrocytes

Reactive oxygen species play a major role in neurodegeneration. Increasing concentrations of peroxide induce neural cell death through activation of pro‐apoptotic pathways. We now report that hydrogen peroxide generated sn‐2 oxidized phosphatidylcholine (OxPC) in neonatal rat oligodendrocytes and that synthetic OxPC [1‐palmitoyl‐2‐(5′‐oxo)valeryl‐sn‐glycero‐3 phosphorylcholine, POVPC] also induced apoptosis in neonatal rat oligodendrocytes. POVPC activated caspases 3 and 8, and neutral sphingomyelinase (NSMase) but not acid sphingomyelinase. Downstream pro‐apoptotic pathways activated by POVPC treatment included the Jun N‐terminal kinase proapoptotic cascade and the degradation of phospho‐Akt. Activation of NSMase occurred within 1 h, was blocked by inhibitors of caspase 8, increased mainly C18 and C24:1 ceramides, and appeared to be concentrated in detergent‐resistant microdomains (Rafts). We concluded that OxPC initially activated NSMase and converted sphingomyelin into ceramide to mediate a series of downstream pro‐apoptotic events in oligodendrocytes.
Sialidase occurs in both membranes of the nuclear envelope and hydrolyzes endogenous GD1a

Previous reports indicated the presence of both gangliosides and sialidase in the nuclear envelope (NE) of primary neurons and the NG108‐15 neural cell line. GM1, one of the major gangliosides of this membrane, was shown to be tightly associated with a sodium‐calcium exchanger in the inner membrane of the NE and to potentiate exchanger activity. GD1a was the other major ganglioside detected in the NE and, like GM1, occurs in both inner and outer membranes. A subsequent report indicated the presence of sialidase activity in the NE without specification as to which of the two membranes express it. The present study was undertaken to determine the nature and locus of this activity within the NE of two cell lines: NG108‐15 and SH‐SY5Y. Western blot analysis of the separated membranes revealed occurrence of Neu3 in the inner membrane and Neu1 in the outer membrane of the NE. Moreover, sialidase activity at both sites was shown capable of catalyzing conversion of endogenous GD1a to GM1.
Effect of 6 Months of Balance Training During Pulmonary Rehabilitation in Patients With COPD

PURPOSE: Balance impairment is recognized as an important issue for patients with chronic obstructive pulmonary disease (COPD). The aim of this study was to examine the effect of balance training as part of pulmonary rehabilitation (PR) on balance in COPD patients. METHODS: Patients were randomly assigned to an intervention or usual care group. The intervention group underwent balance training 3 times a week for 6 months in addition to the standard PR. The control group received 6 months of the standard PR program only. Balance was assessed by the Timed Up and Go (TUG), Tinetti, Berg Balance Scale (BBS), and the Unipodal Stance (UST) tests. Balance confidence was rated using the ABC scale. Exercise tolerance was determined using a 6-Minute Walk Test. RESULTS: Following the completion of PR, the intervention group showed improvement in all balance measures. Only TUG, ABC, and UST scores were improved in the usual care group (P < .05). Results demonstrated significant between-group differences in TUG, Tinetti, BBS, and ABC scores (P < .01) and UST score (P < .05). CONCLUSIONS: Balance training incorporated into a standard PR program significantly improves scores on balance tests in COPD patients.
Avaliação da ativação neuromuscular em indivíduos com escoliose através da eletromiografia de superfície

OBJECTIVE: The aim of this study was to investigate the potential of surface electromyography (EMG) for assessing neuromuscular efficiency and localized muscle fatigue in the lumbar extensors, in individuals with scoliosis. METHODS: Twenty individuals participated in this study, divided equally into two groups: (1) Scoliosis Group and (2) Control Group. These subjects underwent a fatigue induction test on their lumbar extensor muscles, consisting of one maximum voluntary isometric contraction (MVIC) followed by a test at 80% of the MVIC effort. Force and EMG signals were collected simultaneously. The EMG signal was processed in the frequency domain by means of fast Fourier transforms using the median frequency; and in the time domain by calculating the root mean square value. The data were analyzed by means of one-way analysis of variance to investigate the differences between the two groups. Paired t test was used to investigate the symmetry between the right and left sides. The significance level adopted was 0.05. RESULTS: The results showed that the individuals with scoliosis presented: (1) symmetrical neuromuscular activation between the sides; (2) lower neuromuscular efficiency; (3) greater capacity to resist fatigue; and (4) force values 42.6% lower than those of the individuals in the Control Group. CONCLUSIONS: The results suggest that surface EMG is an effective tool for functional assessments of scoliosis, although the protocol established limited the participation of individuals with scoliosis, from the perspective of neuromuscular efficiency.