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The ubiquitin proteasome pathway (UPP) is essential for removing abnormal proteins and preventing accumulation of potentially toxic proteins within the neuron. UPP dysfunction occurs with normal aging and is associated with abnormal accumulation of protein aggregates within neurons in neurodegenerative diseases. Ischemia disrupts UPP function and thus may contribute to UPP dysfunction seen in the aging brain and in neurodegenerative diseases. Ubiquitin carboxy-terminal hydrolase L1 (UCHL1), an important component of the UPP in the neuron, is covalently modified and its activity inhibited by reactive lipids produced after ischemia. As a result, degradation of toxic proteins is impaired which may exacerbate neuronal function and cell death in stroke and neurodegenerative diseases. Preserving or restoring UCHL1 activity may be an effective therapeutic strategy in stroke and neurodegenerative diseases. [ABSTRACT FROM AUTHOR]

Abstract: The thalamus, hippocampus and related glutamatergic neurotransmission pathways have been implicated in the pathophysiology of bipolar disorder. We have reviewed the existing literature over approximately two decades from 1990 to March 2008 for evidence that support structural, functional and chemical neuroimaging abnormalities as well as glutamatergic aberrations of the thalamus and the hippocampus in bipolar disorder. Available structural neuroimaging studies suggest a predominance of negative findings in terms of hippocampal and thalamic volumetric changes in bipolar disorder. Many functional neuroimaging studies however have found activation changes within the thalami, medial temporal lobes, prefrontal regions, and basal ganglia suggesting abnormal limbic–thalamo–cortical circuitry in bipolar disorder. The pattern of findings suggests abnormalities in the regulation of neuronal activity without fixed lesions in the thalamus or hippocampus. This could be related to factors such as cohort heterogeneity, image resolution and whether specific nuclei are examined, or that bipolar disorder is associated with greater neural inefficiency and greater reactivity to emotional stimuli. Chemical neuroimaging studies in bipolar disorder also implicate altered excitatory glutamate neurotransmission as well as cellular and membrane metabolism, especially pronounced within the hippocampus. Within the hippocampus, abnormalities of the ionotropic glutamate receptors were found in bipolar disorder with metabotropic glutamate receptors being relatively understudied. The few immunohistochemical studies performed on the thalamus also suggest the possibility of disturbances of glutamatergic neurotransmission involving intracellular signaling and trafficking processes in bipolar disorder. Overall, the emerging trends from these findings highlight the need for further research to unravel underlying neurobiological changes and clinical correlates of thalamic and hippocampal dysfunction in bipolar disorder. [Copyright &y& Elsevier]

• Mutation of UCHL1's C152 lipid binding site alleviated TBI-induced cell death. • C152 mutation decreased ubiquitinated proteins, activation of autophagy after TBI. • C152 mutation decreased white and gray matter injury after TBI. • C152 mutation improved motor and cognitive function after TBI. Ubiquitin carboxy terminal hydrolase L1 (UCHL1) is a protein highly expressed in neurons that may play important roles in the ubiquitin proteasome pathway (UPP) in neurons, axonal integrity, and motor function after traumatic brain injury (TBI). Binding of reactive lipid species to cysteine 152 of UCHL1 results in unfolding, aggregation, and inactivation of the enzyme. To test the role of this mechanism in TBI, mice bearing a cysteine to alanine mutation at site 152 (C152A mice) that renders UCHL1 resistant to inactivation by reactive lipids were subjected to the controlled cortical impact model (CCI) of TBI and compared to wild type (WT) controls. Alterations in protein ubiquitination and activation of autophagy pathway markers in traumatized brain were detected by immunoblotting. Cell death and axonal injury were determined by histological assessment and anti-amyloid precursor protein (APP) immunohistochemistry. Behavioral outcomes were determined using the beam balance and Morris water maze tests. C152A mice had reduced accumulation of ubiquitinated proteins, decreased activation of the autophagy markers Beclin-1 and LC3B, a decreased number of abnormal axons, decreased CA1 cell death, and improved motor and cognitive function compared to WT controls after CCI; no significant change in spared tissue volume was observed. These results suggest that binding of lipid substrates to cysteine 152 of UCHL1 is important in the pathogenesis of injury and recovery after TBI and may be a novel target for future therapeutic approaches. [ABSTRACT FROM AUTHOR]

• Triaxial behavior of high-strength concrete is valid for 25-mm-diameter specimens. • Scalar correction is proposed for triaxial specimens with reduced aspect ratio. • Non-uniform specimen deformation becomes prevalent at axial strains of 15%. • Reduced specimen geometry is proposed for micro-CT and triaxial Kolsky bar. The triaxial compressive response of high-strength concrete is needed to understand pressure-dependent material behavior, which is important for modeling extreme loading events. However, nondestructive damage analysis and dynamic triaxial experiments require specimens that are smaller than those typically used for model calibration. Reducing the specimen diameter from 50 mm to 25 mm showed negligible differences in the material response of a high-strength concrete (no coarse aggregate). However, a scalar correction factor is proposed to account for reductions in length-to-diameter ratio (L/D). By isolating size effects, results from experiments with scaled specimens can be implemented for model calibration efforts. [ABSTRACT FROM AUTHOR]

Abstract Traumatic brain injury (TBI) is a risk factor for development of chronic neurodegenerative disorders later in life. This review summarizes the current knowledge and concepts regarding the connection between long-term consequences of TBI and aging-associated neurodegenerative disorders including Alzheimer's disease (AD), chronic traumatic encephalopathy (CTE), and Parkinsonism, with implications for novel therapy targets. Several aggregation-prone proteins such as the amyloid-beta (Aβ) peptides, tau proteins, and α-synuclein protein are involved in secondary pathogenic cascades initiated by a TBI and are also major building blocks of the hallmark pathological lesions in chronic human neurodegenerative diseases with dementia. Impaired metabolism and degradation pathways of aggregation-prone proteins are discussed as potentially critical links between the long-term aftermath of TBI and chronic neurodegeneration. Utility and limitations of previous and current preclinical TBI models designed to study the link between TBI and chronic neurodegeneration, and promising intervention pharmacotherapies and non-pharmacologic strategies to break this link, are also summarized. Complexity of long-term neuropathological consequences of TBI is discussed, with a goal of guiding future preclinical studies and accelerating implementation of promising therapeutics into clinical trials. This article is part of the Special Issue entitled "Novel Treatments for Traumatic Brain Injury". Highlights • TBI is a risk factor for development of chronic neurodegenerative disorders later in life. • Prolonged secondary injury cascades after TBI can result in chronic neurodegeneration. • Chronic TBI and aging-related dementias involve similar changes in aggregation prone molecules. • Novel preclinical animal models of TBI are needed to better mimic the human condition. • Polypathology of TBI supports the need for development of multifunctional therapies. [ABSTRACT FROM AUTHOR]

A combined variable temperature 600 MHz NMR/molecular dynamics study of the Ca 2+ -release agent cyclic adenosine 5′-diphosphate ribose (cADPR) was conducted. In addition to elucidating the major and minor orientations of the conformationally flexible furanose rings, γ– (C4′–C5′), and β– (C5′–O5′) bonds, the thermodynamics (Δ H o , Δ S o ) associated with each of these conformational equilibria were determined. Both furanose rings were biased towards a south conformation (64–74%) and both β–bonds heavily favored trans conformations. The R-ring γ–bond was found to exist almost exclusively as the γ + conformer, whereas the A-ring γ–bond was a mixture of the γ + and γ t conformers, with the trans conformer being slightly favored. Enthalpic factors accounted for most of the observed conformational preferences, although the R-ring furanose exists as its major conformation based solely on entropic factors. There was excellent agreement between the NMR and MD results, particularly with regard to the conformer identities, but the MD showed a bias towards γ + conformers. The MD results showed that both N -glycosidic χ–bonds are exclusively syn . Collectively the data allowed for the construction of a model for cADPR in which many of the conformationally flexible units in fact effectively adopt single orientations and where most of the conformational diversity resides in its A-ring furanose and γ–bond. [ABSTRACT FROM AUTHOR]

Abstract: Background: Cyclopentenone prostaglandins have been identified as potential neurotoxic agents in the setting of hypoxia-ischemia. Cyclooxygenase-2 (COX-2), the upstream enzyme responsible for prostaglandin production is upregulated following hypoxic-ischemic brain injury. However, the temporal production and concentration of cyclopentenone prostaglandins has not been described following global brain ischemia.MethodsGlobal brain ischemia was induced in rats by asphyxial cardiac arrest (ACA) followed by resuscitation. Rats were sacrificed between 24h and 7 days following resuscitation and their brains removed. Western blot, immunohistochemistry, and mass spectroscopy were performed. A cohort of rats was pretreated with the COX-2 inhibitor SC58125.ResultsCOX-2 is induced in hippocampus at 24h following ACA. Multiple prostaglandins, including cyclopentenone prostaglandin species, are increased in hippocampus as 24h following ACA. Prostaglandin and cyclopentenone prostaglandin concentrations are returned to baseline at 3 and 7 days post-ischemia. The COX-2 inhibitor SC58125 completely abrogates the post-ischemic increase in prostaglandins and cyclopentenone prostaglandins.ConclusionsProstaglandins, including cyclopentenone prostaglandins, are increased in ischemic brain, peak at 24h and can be attenuated by the COX-2 inhibitor SC58125. These data establish the presence of potentially neurotoxic cyclopentenone prostaglandins in post-ischemic brains, thus identifying a target and therapeutic window for neuroprotective therapies. [Copyright &y& Elsevier]

Abstract: Cerebrospinal fluid (CSF) proteins may be useful biomarkers of neuronal death and ultimate prognosis after hypoxic–ischemic brain injury. Cytochrome c has been identified in the CSF of children following traumatic brain injury. Cytochrome c is required for cellular respiration but it is also a central component of the intrinsic pathway of apoptosis. Thus, in addition to serving as a biomarker, cytochrome c release into CSF may have an effect upon survival of adjacent neurons. In this study, we use Western blot and ELISA to show that cytochrome c is elevated in CSF obtained from pediatric rats following resuscitation from cardiac arrest. Using biotinylated human cytochrome c in culture media we show that cytochrome c crosses the cell membrane and is incorporated into mitochondria of neurons exposed to anoxia. Lastly, we show that addition of human cytochrome c to primary neuronal culture exposed to anoxia improves survival. To our knowledge, this is the first study to show cytochrome c is elevated in CSF following hypoxic ischemic brain injury. Results from primary neuronal culture suggest that extracellular cytochrome c is able to cross the cell membrane of injured neurons, incorporate into mitochondria, and promote survival following anoxia. [Copyright &y& Elsevier]

Abstract: In an effort to find inhibitors that are effective against both Candida and Aspergillus spp., a series of 5(6)-(un)substituted benzotriazole analogs, represented by compounds 3a–3h and 3b′–3f′, were prepared using a crystalline oxirane intermediate 1 previously synthesized in our laboratory. All the compounds were evaluated for inhibitory activity against various species of Candida and Aspergillus. Compounds 3b′ (5,6-dimethylbenzotriazol-2-yl derivative), 3d (5-chlorobenzotriazol-1-yl derivative) and 3e′ (6-methylbenzotriazol-1-yl derivative) exhibited potent antifungal activity, with the MICs for Candida spp. and Aspergillus niger, ranging from 1.6μg/mL to 25μg/mL and 12.5μg/mL to 25μg/mL, respectively. The present work describes the design, synthesis, regioisomer characterization (through COSY and NOESY 2D-NMR spectroscopy and single molecule X-ray crystallography), antifungal evaluation, molecular docking, and structure-activity relationships of the various 5(6)-(un)substituted benzotriazole analogs. [Copyright &y& Elsevier]

Abstract: The post-treatment effects of the selective cyclooxygenase (COX)-2 inhibitor, valdecoxib, were investigated in a rat model of temporary focal ischemia. Valdecoxib reduced basal brain prostaglandin E2 concentrations at dosages that did not affect serum thromboxane B2, consistent with a selective COX-2 effect. Temporary focal cerebral ischemia was produced in rats by middle cerebral artery occlusion for 90 min. There was increased expression of COX-2 protein detected by Western blot and immunocytochemistry within neurons in the ischemic cortex at 4 and 24 h after ischemia. Rats were treated with vehicle or valdecoxib 15 min before or 1.5, 3 and 6 h after cerebral ischemia. Rats were sacrificed and brain infarction volume determined 24 h after ischemia. Valdecoxib treatment was associated with a decrease in infarction volume when administered 15 min before, and 1.5 or 3 h but not 6 h after cerebral ischemia. There were no differences in physiological parameters during the procedure. Valdecoxib administered at 1.5 h after ischemia significantly reduced the concentrations of prostaglandin E2 in ischemic penumbral cortex as compared to the vehicle-treated group and contralateral non-ischemic cortex. These results suggest that COX-2 inhibition with valdecoxib is effective when initiated both before and after middle cerebral artery occlusion. [Copyright &y& Elsevier]

[Display omitted] • The deviator stress dictates damage extent more so than hydrostatic pressures. • Reduced length-to-diameter ratio affects peak stress and damage propagation. • Crack networks become more distributed as confinement pressure increases. • End constraint effects are less substantial at high confining pressures (200 MPa). • Volumetric strain using a single radial gauge is errant at high axial strains. Damage modes are drastically different for concrete under complex stress states. This study investigates damage in high-strength concrete under triaxial loading with confinement pressures up to 200 MPa, while also considering effects from changes in specimen length-to-diameter ratio. Damage was observed and segmented using X-ray microtomography. Hydrostatic pressures up to 200 MPa were fully reversible and caused no detectable damage, thus triaxial deviator stresses dictated damage extent. Brittle failure modes produced shear cracks at angles of 25-30° that became more distributed with increased confinement. Ductile failure modes observed pore collapse with residual strengths being ∼30–50% of pristine strengths. [ABSTRACT FROM AUTHOR]

Abstract: Increasing evidence suggests that apoptosis is a contributing factor to neuronal cell death in traumatic brain injury (TBI). There is increased expression, cleavage and activation of caspases as well as other proteins known to regulate apoptosis in neurons after TBI. These proteins include the proto-oncogene Bcl-2 which belongs to a family of proteins with both pro- and anti-apoptotic properties. To investigate the role of apoptosis in TBI and the importance of Bcl-2 protein on the severity and outcome of injury, Bcl-2 overexpressing transgenic and wild-type control mice were subjected to the controlled cortical impact model of TBI. There was no significant difference in the cleavage of caspase-3 or caspase-9 detected by Western blotting of hippocampal samples from transgenic or wild-type mice after TBI. Bcl-2 transgenic mice had smaller contusion volumes and increased numbers of surviving neurons in CA2 but not other regions of hippocampus compared to wild-type controls. By contrast, there was no difference in motor function determined by the round beam balance and wire grip tests between transgenic and wild-type mice after TBI. Cognitive function assessed by the Morris water maze was also not different between groups. These results suggest that overexpression of Bcl-2 is only partially neuroprotective and other members of this protein family may prove to be more important in protecting neurons from cell death. [Copyright &y& Elsevier]

Abstract: Parkinson''s disease is characterized by a progressive loss of dopaminergic neurons, likely associated with dysregulation of oxidation of catechols, such as dopamine (DA) and 6-hydroxydopamine (6-OHDA), and resulting in oxidative stress. The involvement of cyclooxygenase-2 (COX-2) in pathogenesis of Parkinson''s disease has been suggested. However, specific COX-2 triggered mechanisms participating in catalysis of DA oxidation and enhanced catechol-induced cytotoxicity remain poorly characterized. Here, we demonstrate that in a model biochemical system, recombinant heme-reconstituted COX-2 induced oxidation of 6-OHDA in the course of its peroxidase (H2O2-dependent) and cyclooxygenase (arachidonic acid (AA)-dependent) catalytic half-cycles. Similarly, COX-2 was able to stimulate 6-OHDA oxidation during its peroxidase- and cyclooxygenase half-cycles and caused oxidative stress in homogenates of PC12 cells stably overexpressing the enzyme (but not in mock-transfected cells). In addition, the increased levels of COX-2 were associated with enhanced cytotoxicity of 6-OHDA in stably transfected PC12 cells. Finally, co-oxidation of 6-OHDA by COX-2 triggered production of superoxide radicals critical for both propagation of 6-OHDA oxidation and induction of oxidative stress in COX-2 overexpressing cells. Thus, we conclude that both peroxidase and cyclooxygenase half-cycles of COX-2-catalyzed reactions are essential for COX-2-dependent activation of 6-OHDA oxidation, oxygen radical production, oxidative stress, and cytotoxicity. [Copyright &y& Elsevier]

Abstract: Cyclooxygenase-2 (COX-2) is the predominant isoform of cyclooxygenase in brain. COX-2 activity produces oxidative stress and results in the production of prostaglandins that have many injurious effects. COX-2 transcription is induced by synaptic activity; therefore, COX-2 activity could contribute to epileptic neuronal injury. To address this hypothesis, COX-2 protein expression and PGE2 production were determined after kainate-induced limbic seizures in rats. The effects of a specific COX-2 inhibitor, SC58125, on neuronal survival and PGE2 concentration in the hippocampus were also determined. COX-2 protein expression was increased in CA3, dentate gyrus, and cortex at 18–24 h after seizures. Hippocampal PGE2 levels were increased at 24 h following seizures, and treatment with the selective COX-2 inhibitor SC58125, 3 mg/kg p.o., attenuated the increase in PGE2 concentration. The survival of CA3 neurons at 7 days after seizures was increased in rats treated with SC58125 compared to vehicle controls. There was no effect of drug treatment on body or brain temperature, nor on the duration or rate of Type IV EEG activity. These results suggest that COX-2 activity can contribute to epileptic neuronal injury and that selective COX-2 inhibitors are neuroprotective. [Copyright &y& Elsevier]

Abstract: Cyclooxygenase-2 (COX-2) activity has been implicated in the pathogenesis of neuronal cell death in ischemia and other diseases, but the mechanism by which COX-2 exacerbates cell death is unknown. COX-2 activity is known to induce expression of cyclin D1 in neoplastic cells, and cyclin D1 expression can induce cell death in postmitotic neurons. In the present study, the role of COX-2 and cyclin D1 in neuronal cell death induced by anoxia and ischemia was examined. Treatment with the COX-2 specific inhibitor (NS 398 25 μM) and cyclin D1 inhibitor (flavopiridol 1 μM) increased neuronal survival and inhibited DNA fragmentation after anoxia. NS-398 suppressed anoxia-induced expression of cyclin D1. Flavopiridol inhibited the anoxia-induced increased expression of cyclin D1, but had no effect on COX-2 expression. Treatment with the selective COX-2 inhibitor, SC58125, had no affect on COX-2 expression but partially suppressed cyclin D1 expression in the cortex following middle cerebral artery occlusion in vivo. These results show that COX-2 activity is required for cyclin D1 expression after ischemia in vivo and anoxia in vitro. These data provide support for the hypothesis that cyclin D1 expression is an important mechanism by which COX-2 activity exacerbates ischemic neuronal death. [Copyright &y& Elsevier]

Many central nervous system (CNS) diseases display sexual dimorphism. Exposure to circulating sex steroids is felt to be a chief contributor to this phenomenon; however, CNS diseases of childhood and the elderly also demonstrate gender predominance and/or a sexually dimorphic response to therapies. Here we show that XY and XX neurons cultured separately are differentially susceptible to various cytotoxic agents and treatments. XY neurons were more sensitive to nitrosative stress and excitotoxicity versus XX neurons. In contrast, XX neurons were more sensitive to etoposide- and staurosporine-induced apoptosis versus XY neurons. The responses to specific therapies were also sexually dimorphic. Moreover, gender proclivity in programmed cell death pathway was observed. After cytotoxic challenge, programmed cell death proceeded predominately via an apoptosis-inducing factor-dependent pathway in XY neurons versus a cytochrome c-dependent pathway in XX neurons. This gender-dependent susceptibility is related to the incapacity of XY neurons to maintain intracellular levels of reduced glutathione. In vivo studies further demonstrated an incapacity for male, but not female, 17-day-old rats to maintain reduced glutathione levels within cerebral cortex acutely after an 8-min asphyxial cardiac arrest. This gender difference in sensitivity to cytotoxic agents may be generalized to nonneuronal cells, as splenocytes from male and female 16-18-day-old rats show similar gender-dependent responses to nitrosative stress and staurosporine-induced apoptosis. These data support gender stratification in the evaluation of mechanisms and treatment of CNS disease, particularly those where glutathione may play a role in detoxification, such as Parkinson's disease, traumatic brain injury, and conditions producing cerebrai ischemia, and may apply to non-CNS diseases as well. [ABSTRACT FROM AUTHOR]

Fas is a cell surface death receptor that may play an important role in regulating cell death in neuronal cell types by activation of caspase 8. Cellular FLICE inhibitory protein-long (c-FLIP-L) is an endogenous inhibitor of the activation of caspase 8 by Fas. The current study addresses the role of c-FLIP-L in regulation of cell death in PC12 cells induced by nerve growth factor (NGF) withdrawal and Fas antibody, which acts as a Fas ligand and activates the Fas receptor. A recombinant adeno-associated virus (rAAV) vector that expresses c-FLIP-L was constructed. PC12 cells infected with the c-FLIP-L rAAV were resistant to apoptosis induced by treatment with Fas antibody compared to cells infected with enhanced green fluorescent protein (EGFP) expressing rAAV. Overexpression of c-FLIP-L rAAV inhibited cleavage of caspase 8 induced by Fas antibody treatment. In contrast, treatment with the c-FLIP-L rAAV did not protect PC12 cells from cell death induced by NGF withdrawal. In conclusion, overexpression of c-FLIP-L rAAV inhibits Fas antibody-mediated cell death, but not NGF withdrawal-mediated cell death in PC12 cells. [Copyright &y& Elsevier]

Discusses a study which verified the presence of poly(ADP-ribose) polymerase-1 (PARP-1) and poly(ADP-ribosylation) within mitochondrial fractions from primary cortical neurons and fibroblasts. Inhibition of poly(ADP-ribosylation) within the mitochondrial compartment; Prevention of the release of apoptosis-inducing factor; Reduction of neuronal cell death triggered by oxidative stress.

Increases in brain interstitial excitatory amino acid (EAAI) concentrations after ischemia are ameliorated by use-dependent Na+ channel antagonists and by supplementing interstitial glucose, but the regulation of EAAI after traumatic brain injury (TBI) is unknown. We studied the regulation of EAAI after TBI using the controlled cortical impact model in rats. To monitor changes in EAAI, microdialysis probes were placed in the cortex adjacent to the contusion and in the ipsilateral hippocampus. Significant increases in dialysate EAAI after TBI were found compared to levels measured in sham controls. Treatment with the use-dependent Na+ channel antagonist 619C89 (30 mg/kg i.v.) did not significantly decrease dialysate glutamate compared to vehicle controls in hippocampus (10.4±2.4 vs. 11.9±1.6 μM), but there was significant decrease in dialysate glutamate in cortex after 619C89 treatment (19.3±3 vs. 12.6±1.1 μM, P<0.05). Addition of 30 mM glucose to the dialysate, a treatment that decreases EAAI after ischemia, had no significant effect upon dialysate glutamate after TBI in cortex (20.0±4.9 vs. 11.7±3.4 μM) or in hippocampus (10.9±2.0 vs. 8.9±2.4 μM). These results suggest that neither increased release of EAAs due to Na+ channel-mediated depolarization nor failure of glutamate reuptake due to glucose deprivation can explain the majority of the increase in EAAI following TBI. [Copyright &y& Elsevier]

Cementitious materials exposed to extreme loading conditions are subjected to a wide range of strain rates and confining pressures. To improve modeling capabilities, a triaxial Kolsky bar technique is provided to simultaneously investigate strain rate and pressure dependencies. A cylindrical specimen with diameter and length of 25.4 mm was investigated at quasi-static and dynamic strain rates with confining pressures up to 200 MPa. Annular pulse shapers were incorporated to ensure stress equilibrium under constant strain rate deformations. Furthermore, dynamic pressure variations were theoretically approximated and determined to be negligible. The dynamic increase factor was found to decrease as confining pressures increased. Additionally, a shift in the brittle-to-ductile transition point was also observed to show a more brittle failure mode under dynamic strain rates. Lastly, a dynamic failure surface is presented to illustrate the strain-rate and pressure dependencies of high-strength concrete. • Large-diameter Kolsky bar quantifies interdependency of strain rate and pressure. • Annular pulse shaping incorporated to achieve constant strain rate deformation. • Dynamic increase factor decreases with increasing confining pressure. • Shifting brittle-to-ductile transition point, more brittle at dynamic strain rates. • Dynamic failure surface presented for high-strength concrete. [ABSTRACT FROM AUTHOR]