Astrocytes are key glial cells for the metabolic and functional support of the brain. Mitochondrial quality control (MQC), in particular the balance between mitophagy and mitochondrial biogenesis, is ...a major event for the maintenance of cellular homeostasis. Carbon monoxide (CO) is an endogenous gasotransmitter that inhibits cell death and inflammation by targeting mitochondria. It is well established that CO promotes cytoprotection by increasing mitochondrial population and metabolism (oxidative phosphorylation). Thus, it is hypothesized that CO-induced cytoprotection may also be mediated by the balance between mitophagy and mitochondrial biogenesis. Herein, the carbon monoxide releasing molecule-A1 (CORM-A1) was used in primary cultures of astrocytes to assess CO role on mitochondrial turnover. PINK1/Parkin-dependent mitophagy was stimulated by CORM-A1 following 1 h of treatment. While at 24 h after treatment, CORM-A1 increased mitochondrial population, which may indicate mitochondrial biogenesis. In fact, mitochondrial biogenesis was confirmed by the enhancement of PGC-1α expression that upregulates several mitochondrial transcription factors. Furthermore, inhibition of mitophagy by knocking down PINK1 expression reverted CO-induced mitochondrial biogenesis, indicating that mitochondrial turnover is dependent on modulation of mitophagy. Finally, CORM-A1 prevented astrocytic cell death induced by oxidative stress in a mitophagy-dependent manner. In fact, whenever PINK1 was knocked down, CORM-A1-induced cytoprotection was lost. In summary, CORM-A1 stimulates mitochondrial turnover, which in turn prevents astrocytic cell death. CO cytoprotection depends on increasing mitochondrial population and on eliminating dysfunctional mitochondria.
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•Ex situ solar catalytic pyrolysis was studied using mixed oxides catalyst;•The effect of the parameters on the bio-oil yield and composition was investigated;•The yields of bio-oil ...and hydrocarbons were optimized and validated;•Regenerated catalysts presented a good performance on the bio-oil upgrading.
The use of renewable energy sources in the pyrolysis process for bio-oil production has gained a renewed interest. In this work, ex-situ catalytic solar pyrolysis (ECSP) of microalgae was performed using Mg-Al mixed oxides catalyst derived from hydrotalcite. The effects of biomass loading, reaction time, and catalyst percentage on the pyrolysis product were investigated. The condition that maximizes simultaneously the bio-oil yield and its hydrocarbon content was obtained in an optimization study. A study of the effect of catalyst reuse on the pyrolysis process was also performed. The results showed that high yields of bio-oil were found when intermediary values of independent variables were used. The use of the catalyst derived from hydrotalcite improved the quality of bio-oil, promoting a reduction of oxygenated compounds and forming aromatic and long-chain aliphatic hydrocarbons. High bio-oil yield (38.55%) with high hydrocarbon content (32.65%) was achieved under the optimal conditions. The study of the catalyst reuse showed that the structure and surface area of fresh and regenerated catalyst were very similar. In addition, the hydrocarbon content of bio-oil did not significantly change after three pyrolysis cycles.
Carbon monoxide (CO) is a cytoprotective endogenous gas that is ubiquitously produced by the stress response enzyme heme-oxygenase. Being a gas, CO rapidly diffuses through tissues and binds to ...hemoglobin (Hb) increasing carboxyhemoglobin (COHb) levels. COHb can be formed in erythrocytes or in plasma from cell-free Hb. Herein, it is discussed as to whether endogenous COHb is an innocuous and inevitable metabolic waste product or not, and it is hypothesized that COHb has a biological role. In the present review, literature data are presented to support this hypothesis based on two main premises: (i) there is no direct correlation between COHb levels and CO toxicity, and (ii) COHb seems to have a direct cytoprotective and antioxidant role in erythrocytes and in hemorrhagic models in vivo. Moreover, CO is also an antioxidant by generating COHb, which protects against the pro-oxidant damaging effects of cell-free Hb. Up to now, COHb has been considered as a sink for both exogenous and endogenous CO generated during CO intoxication or heme metabolism, respectively. Hallmarking COHb as an important molecule with a biological (and eventually beneficial) role is a turning point in CO biology research, namely in CO intoxication and CO cytoprotection.
The present work demonstrates the ability of CO to prevent apoptosis in a primary culture of astrocytes. For the first time, the antiapoptotic behavior can be clearly attributed to the inhibition of ...mitochondrial membrane permeabilization (MMP), a key event in the intrinsic apoptotic pathway. In isolated non-synaptic mitochondria, CO partially inhibits (i) loss of potential, (ii) the opening of a nonspecific pore through the inner membrane, (iii) swelling, and (iv) cytochrome c release, which are induced by calcium, diamide, or atractyloside (a ligand of ANT). CO directly modulates ANT function by enhancing ADP/ATP exchange and prevents its pore-forming activity. Additionally, CO induces reactive oxygen species (ROS) generation, and its prevention by β-carotene decreases CO cytoprotection in intact cells as well as in isolated mitochondria, revealing the key role of ROS. On the other hand, CO induces a slight increase in mitochondrial oxidized glutathione, which is essential for apoptosis modulation by (i) delaying astrocytic apoptosis, (ii) decreasing MMP, and (iii) enhancing ADP/ATP translocation activity of ANT. Moreover, CO and GSSG trigger ANT glutathionylation, a post-translational process regulating protein function in response to redox cellular changes. In conclusion, CO protects astrocytes from apoptosis by preventing MMP, acting on ANT (glutathionylation and inhibition of its pore activity) via a preconditioning-like process mediated by ROS and GSSG.
It is generally assumed that in order to preserve Bose symmetry in the left- (or right-chiral) current it is necessary to equally distribute the chiral anomaly between the vectorial and the axial ...Ward identities, requiring the use of counterterms to restore consistency. In this work, we show how to calculate the quantum breaking of the left- and right-chiral currents in a way that allows to preserve Bose symmetry independently of the chiral anomaly, using the implicit regularization method.
Lolium multiflorum grass is the major pollen allergen source in the southern region of Brazil, but most of its allergens remain poorly characterized. The aim of this study was to investigate antibody ...reactivity to L. multiflorum crude and carboxymethylligand extracts in allergic patients and healthy individuals. Ion exchange carboxymethyl (CM) chromatography (CM-Sepharose) was used to isolate proteins (S2) from L. multiflorum crude extract (S1), which were assessed by SDS-PAGE. S1- and S2specific IgE and IgG4 levels were measured by ELISA using sera from 55 atopic and 16 non- atopic subjects. Reactive polypeptide bands in S1 and S2 were detected by immunoblotting, and the most prominent bands in S2 were analyzed by mass spectrometry (MS-MS). Similar IgE and IgG4 levels were observed to both S1 (IgE median absorbance: 1.22; IgG4 median absorbance: 0.68) and S2 (IgE median absorbance: 1.26; IgG4 median absorbance: 0.85) in atopic subjects. S1 and S2 had positive correlations for IgE and IgG4 (IgE: r=0.9567; IgG4: r=0.9229; P<0.0001) levels. Homology between S1 and S2 was confirmed by IgE (84%) and IgG4 (83%) inhibition. Immunoblotting revealed that the 29-32 kDa band was recognized by 100% of atopic subjects in both S1 and S2. MS-MS analysis identified similarity profile to groups 1 and 5 grass allergens. This study revealed thatcarboxymethyl-ligand fraction played an important role for pollen allergy diagnosis by containing clinically relevant allergens and constituted a promising candidate for allergen-specific immunotherapy. Key words: Allergen; Ion-exchange chromatography; Beta-expansin; Lolium multiflorum; IgE; IgG4
We address the study of gauge invariance in the Standard Model extension which encompasses all Lorentz-violating terms originated by spontaneous symmetry breaking at the Planck scale. In particular, ...we fully evaluate Ward identities involving two- and three-point functions and derive the conditions which assure gauge invariance of the electromagnetic sector of the Standard Model extension at one loop. We show that momentum routing invariance is sufficient to fix arbitrary and regularization dependent parameters intrinsic to perturbation theory in the diagrams involved. A scheme which judiciously collects finite but undetermined quantum corrections is employed, a particularly subtle issue in the presence of gamma 5 matrices.
Doping strategies for increased performance in BiFeO3 KHOMCHENKO, V. A; KISELEV, D. A; RUBINGER, R. M ...
Journal of magnetism and magnetic materials,
06/2009, Letnik:
321, Številka:
11
Conference Proceeding, Journal Article
Recenzirano
Investigation of crystal structure, dielectric, magnetic and local ferroelectric properties of the diamagnetically substituted Bi1-xAxFeO3-x/2 (A=Ca, Sr, Pb, Ba; x=0.,0.3) polycrystalline samples has ...been carried out. It has been shown that the heterovalent A2+ substitution result in the formation of oxygen vacancies in the host lattice. The solid solutions have been found to possess a rhombohedrally distorted perovskite structure described by the space group R3c. Piezoresponse force microscopy has revealed signs of existence of the ferroelectric polarization in the samples at room temperature. Magnetization measurements have shown that the magnetic state of these compounds is determined by the ionic radius of the substituting elements. A-site substitution with the biggest ionic radius ions has been found to suppress the spiral spin structure of BiFeO3 giving rise to the appearance of room-temperature weak ferromagnetism.
Abstract Global cerebral ischemia induces selective acute neuronal injury of the CA1 region of the hippocampus. The type of cell death that ensues may include different programmed cell death ...mechanisms namely apoptosis and necroptosis, a recently described type of programmed necrosis. We investigated whether necroptosis contributes to hippocampal neuronal death following oxygen-glucose deprivation (OGD), an in vitro model of global ischemia. We observed that OGD induced a death receptor (DR)-dependent component of necroptotic cell death in primary cultures of hippocampal neurons. Additionally, we found that this ischemic challenge upregulated the receptor-interacting protein kinase 3 (RIP3) mRNA and protein levels, with a concomitant increase of the RIP1 protein. Together, these two related proteins form the necrosome, the complex responsible for induction of necroptotic cell death. Interestingly, we found that caspase-8 mRNA, a known negative regulator of necroptosis, was transiently decreased following OGD. Importantly, we observed that the OGD-induced increase in the RIP3 protein was paralleled in an in vivo model of transient global cerebral ischemia, specifically in the CA1 area of the hippocampus. Moreover, we show that the induction of endogenous RIP3 protein levels influenced neuronal toxicity since we found that RIP3 knock-down (KD) abrogated the component of OGD-induced necrotic neuronal death while RIP3 overexpression exacerbated neuronal death following OGD. Overexpression of RIP1 also had deleterious effects following the OGD challenge. Taken together, our results highlight that cerebral ischemia activates transcriptional changes that lead to an increase in the endogenous RIP3 protein level which might contribute to the formation of the necrosome complex and to the subsequent component of necroptotic neuronal death that follows ischemic injury.
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