Changes In Redox State Research Articles

Sevoflurane Effects on Neuronal Energy Metabolism Correlate with Activity States While Mitochondrial Function Remains Intact.

During general anesthesia, alterations in neuronal metabolism may induce neurotoxicity and/or neuroprotection depending on the dose and type of the applied anesthetic. In this study, we investigate the effects of clinically relevant concentrations of sevoflurane (2% and 4%, i.e., 1 and 2 MAC) on different activity states in hippocampal slices of young Wistar rats. We combine electrophysiological recordings, partial tissue oxygen (ptiO2) measurements, and flavin adenine dinucleotide (FAD) imaging with computational modeling. Sevoflurane minimally decreased the cerebral metabolic rate of oxygen (CMRO2) while decreasing synaptic transmission in naive slices. During pharmacologically induced gamma oscillations, sevoflurane impaired network activity, thereby decreasing CMRO2. During stimulus-induced neuronal activation, sevoflurane decreased CMRO2 and excitability while basal metabolism remained constant. In this line, stimulus-induced FAD transients decreased without changes in basal mitochondrial redox state. Integration of experimental data and computer modeling revealed no evidence for a direct effect of sevoflurane on key enzymes of the citric acid cycle or oxidative phosphorylation. Clinically relevant concentrations of sevoflurane generated a decent decrease in energy metabolism, which was proportional to the present neuronal activity. Mitochondrial function remained intact under sevoflurane, suggesting a better metabolic profile than isoflurane or propofol.

Kaempferitrin inhibits colorectal cancer cells by inducing reactive oxygen species and modulating PI3K/AKT signalling pathway

Colorectal cancer is a life-threatening malignancy of high invasive death worldwide, despite improvements in conventional chemotherapy. Hence, there is an urgent need for new and effective anti-colorectal chemotherapeutic agents. Kaempferitrin can inhibit colon cancer cell viability, apoptotic induction, and reactive oxygen species (ROS) generation in a concentration-dependent way. Kaempferitrin had a cytotoxic and anti-proliferative effect on HT-29 colorectal cancer cells at a dosage of 30 µM, regulate apoptotic cell death, cell proliferation, and the cellular antioxidant system. Hyperoxia, cellular stress, ROS, and oxidative damage are the regulators of cancer cells. Increased sensitivity towards oxidative stress is caused by a change in redox state caused by enhanced ROS generation. In HT-29 cells, kaempferitrin also activated caspase-3 and enhanced the ratios of cleaved PARP protein expression, triggering caspase-dependent death. These kaempferitrin-induced processes also correlate with PI3K/AKT, implying downstream targeting of the cancer cell pathway. These findings suggest that kaempferitrin could be a promising therapeutic agent for the treatment of CRC, since it inhibits CRC cell proliferation and induces apoptosis via the PI3K/AKT signalling pathway.

Metabolic profiling of prostate cancer in skeletal microenvironments identifies G6PD as a key mediator of growth and survival.

The spread of cancer to bone is invariably fatal, with complex cross-talk between tumor cells and the bone microenvironment responsible for driving disease progression. By combining in silico analysis of patient datasets with metabolomic profiling of prostate cancer cells cultured with bone cells, we demonstrate the changing energy requirements of prostate cancer cells in the bone microenvironment, identifying the pentose phosphate pathway (PPP) as elevated in prostate cancer bone metastasis, with increased expression of the PPP rate-limiting enzyme glucose-6-phosphate dehydrogenase (G6PD) associated with a reduction in progression-free survival. Genetic and pharmacologic manipulation demonstrates that G6PD inhibition reduces prostate cancer growth and migration, associated with changes in cellular redox state and increased chemosensitivity. Genetic blockade of G6PD in vivo results in reduction of tumor growth within bone. In summary, we demonstrate the metabolic plasticity of prostate cancer cells in the bone microenvironment, identifying the PPP and G6PD as metabolic targets for the treatment of prostate cancer bone metastasis.

Evidence for the oxidation of Earth\u2019s crust from the evolution of manganese minerals

Analysis of manganese mineral occurrences and valence states demonstrate oxidation of Earth’s crust through time. Changes in crustal redox state are critical to Earth’s evolution, but few methods exist for evaluating spatially averaged crustal redox state through time. Manganese (Mn) is a redox-sensitive metal whose variable oxidation states and abundance in crustal minerals make it a useful tracer of crustal oxidation. We find that the average oxidation state of crustal Mn occurrences has risen in the last 1 billion years in response to atmospheric oxygenation following a 66 ± 1 million-year time lag. We interpret this lag as the average time necessary to equilibrate the shallow crust to atmospheric oxygen fugacity. This study employs large mineralogical databases to evaluate geochemical conditions through Earth’s history, and we propose that this and other mineral data sets form an important class of proxies that constrain the evolving redox state of various Earth reservoirs.

The Role of Redox Status Changes in Dexamethasone-Induced Apoptosis in Jurkat Tumor Cells.

The apoptotic death and its regulation was studied in intact Jurkat tumor cells and under the influence of buthionine-sulfoximine (de novo glutathione synthesis inhibitor; 1 mM) and/or apoptosis inducer dexamethasone (10 μM). The role of glutathione system components in dexamethasone-induced apoptosis in Jurkat tumor cells (both receptor-mediated and mitochondrial pathways) was analyzed. Under conditions of dexamethasone-induced apoptosis, glutathione system blockage mostly affects presentation of TNF RI- and Fas-receptors in Jurkat tumor cells, as well as change in content of transcription factors Apaf-1 and NF-κB, thereby promoting cell death. The decrease in the content of oxidized glutathione produced a potentiating effect on dexamethasone-induced apoptotic death of Jurkat tumor cells.

Salinity induced redox metabolic shift influence hormonal profile and germination performance of two contrasting indica rice cultivars

The role of redox deviations under salinity on metabolic dysfunction associated with progression of seed germination is well documented. However, the correlative evaluation of the salinity induced changes in the redox system and hormonal profile in regulating germination are least studied and hence is the subject of present investigation. Imposition of post imbibitional salinity stress (PISS) to two contrasting rice genotypes differing in sensitivity towards salinity (Oryza sativa L., Cultivars Patnai and IR29) caused differential and significant redox-metabolic shift and germination performances. Biomarkers of oxidative stress like, accumulation of total ROS, in situ localization of hydrogen peroxide, radical scavenging property, and lipid peroxidation are assessed for the determination of salinity induced differential changes in redox status of both the experimental cultivars. Salt resistant cultivar Patnai exhibiting better redox regulatory property under PISS in terms of controlled generation of ROS (DCFDA oxidation, H2O2 content) with greater elicitation of total antioxidant capacity (DPPH radical scavenging property), contends lipid peroxidation (accumulation of TBARS) as compared to the salt-sensitive cultivar IR 29. RP-HPLC based estimation of PISS-induced alteration in hormonal pools showed strong correlation between altered redox status (assessed in terms of redox biomarkers) and hormonal profile (endogenous titer of gibberellic acid (GA3), abscisic acid (ABA) and jasmonic acid (JA)) and germination and other physiological phenotypes (t50 value, allocation index, relative water content, and Na+ / K+ ratio) of the experimental rice germplasms, suggesting the influence of differential shift in redox status on germination hormones and early growth performances. Taken as a whole, the work proposes close connection between salinity induced changes in oxidative windows and hormonal profile of germinating seeds, necessary for better management of salinity stress in agriculture.

Redox heterogeneity of picritic lavas with respect to their mantle sources in the Emeishan large igneous province

The oxygen fugacity (fO2) of the Earth’s mantle is a key parameter that regulates fundamental geological processes such as planetary differentiation, mantle melting, and volatile cycling. Large igneous provinces (LIPs) are among the most voluminous mafic volcanic eruptions in the Earth’s history. Constraining the fO2 of LIP rocks is critical for understanding the redox state of the mantle and migration of volatiles from the deep Earth to the atmosphere. Here, we investigated primitive picrites from the Dali and Lijiang areas belonging to the Emeishan LIP, which contain early-crystallized olivine phenocrysts with Fo contents up to 93.5 and 91.9, respectively. The fO2 conditions of primary and derivative melts are determined by the olivine-spinel and olivine-melt V oxybarometers, aided by temperature estimates from olivine-spinel Al and olivine-melt Sc/Y thermometers. The calculated fO2 values are negatively correlated with olivine Fo contents due to fractionation of mafic minerals in a system closed to oxygen. The fO2s of Dali and Lijiang primary melts are −0.8 ± 0.4 and + 0.6 ± 0.3 (1σ) ΔFMQ log units, respectively, more variable than those of primitive MORBs, indicating significant fO2 fluctuations in primary magmas from the Emeishan LIP caused by changes in both redox state of the source rock and depth of melt extraction. Melt barometer constrains the Dali and Lijiang primary melts generated at 4.7 and 3.0 GPa, respectively. After correcting for the depth effect, the Dali and Lijiang sources are more oxidized (with higher Fe3+/∑Fe ratios), in varying degrees, than the ambient upper mantle, likely due to incorporation of recycled surface materials. Under such oxidized conditions, mantle carbon is efficiently extracted during melting in the form of CO2 and released to the atmosphere during massive magma emplacement, which may have played an important role in causing the climatic and environmental changes and triggering the end-Guadalupian mass extinction.

Redox-Switchable Allosteric Effects in Molecular Clusters.

We demonstrate that allosteric effects and redox state changes can be harnessed to create a switch that selectively and reversibly regulates the coordination chemistry of a single site on the surface of a molecular cluster. This redox-switchable allostery is employed as a guiding force to assemble the molecular clusters Zn3Co6Se8L′6 (L′ = Ph2PN(H)Tol, Ph = phenyl, Tol = 4-tolyl) into materials of predetermined dimensionality (1- or 2-D) and to encode them with emissive properties. This work paves the path to program the assembly and function of inorganic clusters into stimuli-responsive, atomically precise materials.

Characterization of the AGR2 Interactome Uncovers New Players of Protein Disulfide Isomerase Network in Cancer Cells

Anterior gradient 2 (AGR2) is an endoplasmic reticulum (ER)-resident protein disulfide isomerase (PDI) known to be overexpressed in many human epithelial cancers and is involved in cell migration, cellular transformation, angiogenesis, and metastasis. This protein inhibits the activity of the tumor suppressor p53, and its expression levels can be used to predict cancer patient outcome. However, the precise network of AGR2-interacting partners and clients remains to be fully characterized. Herein, we used label-free quantification and also stable isotope labeling with amino acids in cell culture–based LC–MS/MS analyses to identify proteins interacting with AGR2. Functional annotation confirmed that AGR2 and its interaction partners are associated with processes in the ER that maintain intracellular metabolic homeostasis and participate in the unfolded protein response, including those associated with changes in cellular metabolism, energy, and redox states in response to ER stress. As a proof of concept, the interaction between AGR2 and PDIA3, another ER-resident PDI, was studied in more detail. Pathway analysis revealed that AGR2 and PDIA3 play roles in protein folding in ER, including post-translational modification and in cellular response to stress. We confirmed the AGR2–PDIA3 complex formation in cancer cells, which was enhanced in response to ER stress. Accordingly, molecular docking characterized potential quaternary structure of this complex; however, it remains to be elucidated whether AGR2 rather contributes to PDIA3 maturation in ER, the complex directly acts in cellular signaling, or mediates AGR2 secretion. Our study provides a comprehensive insight into the protein–protein interaction network of AGR2 by identifying functionally relevant proteins and related cellular and biochemical pathways associated with the role of AGR2 in cancer cells.

Redox state changes of mitochondrial cytochromes in brain and breast cancers by Raman spectroscopy and imaging

This paper presents a non-invasive approach to study redox status of cytochromes in vitro human brain cells of normal astrocytes (NHA), astrocytoma (CRL-1718), glioblastoma (U87-MG) and medulloblastoma (Daoy), and human breast cells of normal cells (MCF10A), slightly malignant cells (MCF7) and highly aggressive cells (MDA-MB-231), in vivo animal models, and ex vivo brain and breast tissues surgically resected human specimens by means of Raman microspectroscopy at 355 nm, 532 nm, 785 nm and endospectroscopic Raman probe at 785 nm. Here we show that the amount of reduced cytochrome becomes abnormally high in human brain tumors and breast cancers. In contrast, the amount of reduced cytochrome c is lower in cancer cells when compared to the normal one at in vitro conditions when the effect of microenvironment is eliminated. Mitochondrial dysfunction and alterations in the chemical composition of the nucleus, mitochondria, lipid droplets, cytoplasm in single cells have been detected by Raman imaging. Incubation in vitro with retinoic acid increases the amount of reduced cytochrome c.

Spectroelectrochemistry of Proteins

AbstractThis mini review addresses the evolution of spectroelectrochemistry from the laboratories of Professor Theodore Kuwana into the examination of proteins. Synchronizing electrochemical and spectral properties of proteins enables the identification of functions of redox centers, and their kinetics and thermodynamics. Changes in conformation and redox states are examined by a variety of spectroscopic techniques by directly observing protein reactions at electrodes with modified surfaces.

A primary effect of palmitic acid on mouse oocytes is the disruption of the structure of the endoplasmic reticulum.

Exposure of mouse oocytes to saturated fatty acids (FAs) such as palmitic acid (PA) has been shown to increase lipid content and cause an endoplasmic reticulum (ER) stress response and changes in the mitochondrial redox state. PA can also disrupt Ca2+ stores in other cell types. The links between these intracellular changes, or whether they are prevented by mono-unsaturated FAs such as oleic acid (OA), is unclear. Here, we have investigated the effects of FAs on mouse oocytes, that are maturated in vitro, using coherent anti-Stokes Raman scattering and two-photon fluorescence microscopy. When oocytes were matured in the presence of PA, there were changes in the aggregation pattern and size of lipid droplets that were mitigated by co-incubation in OA. Maturation in PA alone also caused a distinctive disruption of the ER structure. This effect was prevented by incubation of OA with PA. In contrast, maturation of mouse oocytes in medium containing PA was not associated with any significant change in the redox state of mitochondria or the Ca2+ content of intracellular stores. These data suggest that a primary effect of saturated FAs such as PA on oocytes is to disrupt the structure of the ER and this is not due to an effect on the mitochondria or Ca2+ stores.

Sixty-Four Hour Changes in Oral-Intestinal, Extracellular, and Intracellular Redox Status After an All-Day Maillard-Coated Food Binge Followed by Two Days of Redox/Digestion-Balanced Culinary Medicine: A Pilot Single Case Analysis

Browned, melanoidin-coated, and Maillard reaction end-product-covered convenience and fast-foods are as addictive as street drugs. And drive overeating, systemic oxidative stress (SOS: pE- > pH+), and systemic reductive stress (SRS: pE- < pH+), overweight, and the leading causes of mortality and morbidity worldwide. Redox/digestion-balanced culinary medicine protocols are absent as healthcare professionals and the people they serve begin to recognize that Maillard abuse disorder is the main obstacle to self-actualization and a long, accomplished, and content energetically ambulatory extended lifespan. A PubMed search revealed no studies exhibiting sixty-four-hour changes in oral-intestinal, extracellular, and intracellular redox status after an all-day Maillard-coated food spree followed by two days of redox/digestion-balanced culinary medicine. The purpose of this single case study is to analyze changes, if any, in oral-intestinal, extracellular, and intracellular redox status after an all-day Maillard-coated binge followed by two days of redox/digestion-balanced culinary medicine and examine the feasibility of more extensive investigations. The participant met inclusion criteria, drank Maillard-rich colas for breakfast, a small pizza, a peanut butter shake for lunch, a double bacon cheeseburger, and a dozen chicken wings for dinner and provided blood and urine samples. The volunteer then underwent redox/digestion-balanced culinary medicine detoxification and provided laboratory samples. TSH, TG/HDL ratio, VLDL/HDL ratio, LDL/HDL ratio, and urine pH+ measured oral-intestinal and extracellular redox status. The neutrophil-to-lymphocyte and platelet-to-lymphocyte ratios assessed intracellular redox status. It took sixty-four hours for the participant’s body and mind to neutralize the toxic manifestations of a day-long binge on Maillard reaction intermediate and end-products, melanoidins, advanced glycation end-products (AGEs), and advanced lipoxidation endproducts-coated and containing foods and beverages. More extensive investigations are needed to increase the Maillard abuse detoxification options. Healthcare professionals and the people they serve increasingly recognize that Maillard abuse is the main obstacle to self-actualization and a long, accomplished, and energetically ambulatory lifespan.

Abstract 14416: The Redox Effect of Stem-Cell Derived Extracellular Vesicles on Normal and Diabetic Human Coronary Artery Endothelial Cells

Introduction: Cardiovascular disease continues to be the leading cause of death globally, necessitating the study of novel therapeutic modalities. Following the lack of success with stem-cell based therapies, their extracellular vesicles (EVs) have emerged as a promising strategy. Hypothesis: We hypothesized that EVs will reduce oxidative stress in normal and diabetic human coronary artery endothelial cells (HCAEC). Methods: Human bone marrow-derived stem cells (HBMSC) were grown to passage 7 and subject to 24 hours of preconditioning by serum starvation media. EVs were then isolated via ultracentrifugation and submitted for LC-MS/MS for proteomics. Normal HCAEC and diabetic HCAEC (DM-HCAEC) were starved for 12 hours then treated with vehicle (1% DMSO in PBS) or EVs (1x108 particles/ml) for 6 hours. Following treatment, mitochondrial (mito) ROS using mitosox, total ROS using DCF-DA, and protein expression using Western blots were analyzed by 2-way ANOVA with Bonferroni multiple-comparisons correction. Results: A total of 473 EV proteins were identified, among which were antioxidants catalase, thioredoxin, peroxiredoxins, SOD1, and ferritin. EV-treatment reduced mito-ROS levels significantly in HCAEC, but not in DM-HCAEC. Basal (ambient) levels of total ROS in DM-HCAEC were significantly higher compared to HCAEC (p=0.0393), however, EV treatment reduced total ROS in both cell types significantly (p=0.002). Western blot analysis revealed that EV increased mitochondrial antioxidant MnSOD (SOD2) levels in HCAEC but not in DM-HCAEC. Catalase expression was unaffected by EV treatment in both cell types. Conclusions: EVs displayed differential effects on the mito-ROS, but reduced total ROS in both HCAEC and DM-HCAEC. EV-induced reduction in mito-ROS in non-diabetic HCAEC plausibly resulted from corresponding increase in MnSOD expression. Data from our ongoing studies will be presented at the meeting demonstrating whether the above changes in redox states by EVs correspond to differential proliferation, migration and angiogenesis in HCAEC vs. DM-HCAEC.

Abstract 10099: Loss of CD70 Impairs Nitric Oxide Homeostasis and Augments Intracellular Oxidative Stress in Endothelial Cells

Introduction: TNF superfamily ligands exert multiple effects on endothelial cell (EC) function, metabolism, and redox status. CD70 is a TNF superfamily member classically expressed on antigen-presenting cells and drives T memory cell polarization. Despite evidence of expression by ECs, the role of CD70 in endothelial biology has not been defined. We hypothesized that CD70 affects EC function through regulation of nitric oxide (NO) generation and cellular oxidative stress. Methods: Human aortic and pulmonary artery ECs (HAECs and HPAECs, respectively) were transfected with control and CD70-directed siRNA (siCD70). NO levels of individual cells were monitored in real-time after stimulation with ATP using the intracellular fluorescent biosensor c-geNOp. Similarly, intracellular hydrogen peroxide was assayed in real-time using the intracellular fluorescent biosensor Hyper7 following stimulation by auranofin and histamine. For both studies, 70-100 individual cells, averaged over 4 experiments, were analyzed using confocal microscopy. Control and siCD70-treated cell lysates (n = 4-6) were analyzed by Western blot and quantitative RT-PCR, as well as for glutathione peroxidase (GPx) enzyme activity. Results: CD70 knockdown was associated with a reduction in agonist-stimulated NO levels in HAECs and HPAECs by 30% and 40%, respectively. Protein levels of eNOS decreased after CD70 knockdown, with a reduction of 50% in HAECs and 75% in HPAECs. Phosphorylation at Ser1177 of eNOS in response to EC stimulation with ATP was reduced after siCD70 treatment, and expression of the key eNOS-stimulatory protein Hsp90 was decreased. Intracellular hydrogen peroxide was significantly increased (20% in HAECs and 80% in HPAECs) following ROS stimulation in siCD70-treated versus control cells. This change in redox status was associated with a decrease in mitochondrial superoxide dismutase protein and an increase in GPx-1 expression and enzyme activity. Conclusions: Loss of CD70 in ECs is associated with reduced eNOS expression and bioactivity as well as increased susceptibility to intracellular oxidative stress, potentially from a mitochondrial source. These results suggest an important homeostatic role for CD70 in endothelial function and redox status.

Cloning and characterization of microphthalmia‐associated transcription factor‐like gene provide insights into Cyclina sinensis clam shell melanin deposition

The reversible black shell colour change in the clam Cyclina sinensis functions as an adaptation to different environmental conditions (within or outside of muddy sediment) due to changes in the melanin redox state in the shell. The microphthalmia-associated transcription factor (MITF) is a melanocyte-specific transcription factor that is involved in the differentiation, proliferation and survival of melanocytes. In this study, the full-length cDNA sequence of the mitf-like gene was obtained from C. sinensis using RACE PCR. The mitf-like cDNA is 1725 bp in length, containing a 47 bp 5′ untranslated region (UTR), a 1398 bp open reading frame and a 280 bp 5′ untranslated region. The mitf-like gene contains seven exons separated by six introns, and it encodes a putative protein of 465 amino acids with a highly conserved domain of MITF containing a basic helix-loop-helix leucine zipper (bHLH-LZ). The phylogenetic analysis of amino acid sequences using neighbour-joining and maximum likelihood methods revealed that C. sinensis is closely related to Meretrix petechialis. Additionally, the mRNA expression of mitf-like and melanin was high in the outer margin of the mantle, suggesting that the mitf-like might play an important role in melanin synthesis in the mantle by regulating the cell cycle and survival of melanocytes; however, its role in C. sinensis shell melanin deposition requires further investigation.

Protein sulfenylation contributes to oxidative burst-triggered responses during the interaction between Botrytis cinerea and Nicotiana benthamiana

Reactive oxygen species (ROS) play a crucial role as signaling molecules in plant responses to pathogen infection. It is highly reactive with cellular components such as DNA, lipids and proteins, thereby leading to serious oxidative damages. Cysteine residues are sensitive targets of ROS in a post-translational modification known as sulfenylation. However, during plant-pathogen interaction, it is still unclear which specific proteins can be oxidized by ROS and undergo sulfenic modification to regulate the interaction process. Here, we observed a biphasic production of ROS in Nicotiana benthamiana after inoculation with Botrytis cinerea. RT-qPCR results showed that the biphasic increase in ROS production was closely related to the expression of NbRbohA, NbRbohB and NbRbohC. Furthermore, a ROS-dependent sulfenome analysis was performed and finally 183 differentially sulfenylated proteins were identified. Their post-translational sulfenylation modification in response to B. cinerea infection was further confirmed by western blot and mass spectrometry analysis. Virus-induced gene silencing of those genes encoding sulfenylated proteins resulted in reduced resistance to B. cinerea. Taken together, our data demonstrate that B. cinerea infection induces ROS burst in N. benthamiana, which triggers protein sulfenylation to ensure the transduction of ROS signals and further function in plant-pathogen interaction. SignificanceReactive oxygen species (ROS) induced by Botrytis cinerea infection trigger changes in cellular redox status through protein sulfenylation to be involved in plant-pathogen interaction.

Feeding effects on liver mitochondrial bioenergetics of Boa constrictor (Serpentes: Boidae)

Snakes are interesting examples of taxa that can overcome energy metabolism challenges, as many species can endure long periods without feeding, and their eventual meals are of reasonably large sizes, thus exhibiting dual extreme adaptations. Consequently, metabolic rate increases considerably to attend to the energetic demand of digestion, absorption and protein synthesis. These animals should be adapted to transition from these two opposite states of energy fairly quickly, and therefore we investigated mitochondrial function plasticity in these states. Herein, we compared liver mitochondrial bioenergetics of the boid snake Boa constrictor during fasting and after meal intake. We fasted the snakes for 60 days, and then we fed a subgroup with 30% of their body size and evaluated their maximum postprandial response. We measured liver respiration rates from permeabilized tissue and isolated mitochondria. From isolated mitochondria, we also measured Ca2+ retention capacity and redox status. Mitochondrial respiration rates were maximized after feeding, reaching an approximately 60% increase from fasting levels when energized with complex I-linked substrates. Interestingly, fasting and fed snakes exhibited similar respiratory control ratios and citrate synthase activity. Furthermore, we found no differences in Ca2+ retention capacity, indicating no increase in susceptibility to mitochondrial permeability transition, and no changes in mitochondrial redox state, although fed animals exhibited increases in the release of H2O2. Thus, we conclude that liver mitochondria from B. constrictor snakes increase respiration rates during the postprandial period and quickly improve the bioenergetic capacity without compromising redox balance.

Increased endogenous reactive oxygen species normalizes proliferation defects of Bmi1 heterozygous knockout neural stem cells.

The Bmi1gene, one of transcriptional suppressor genes in multi-comb family, maintains proliferation of neural stem cells (NSCs) and redox homeostasis. However, heterozygous deletion of the Bmi1 gene (Bmi1+/-) does not reduce the proliferative ability of NSCs. The aim of the present study was to reveal the underlying mechanism of this phenotype. NSCs derived from the cortex of newborn Bmi1+/- and wild-type (WT) mice were treated with different concentrations of hydrogen peroxide (H2O2) and antioxidant N-acetyl-L-cysteine (NAC) for 24 h followed by analyses of NSC proliferation and oxidative stress-related indexes. The levels of reactive oxygen species (ROS) of Bmi1+/--NSCs were slightly higher than that of WT-NSCs at baseline. H2O2 increased ROS and NAC reduced ROS in a concentration-dependent pattern, but the change was significantly greater in Bmi1+/--NSCs than WT-NSCs. The proliferation and self-renewal ability of Bmi1+/--NSCs and WT-NSCs were comparable in a basic state. After 1 μM H2O2 treatment, Brdu incorporation ratio, cell viability, total antioxidant capacity (T-AOC) and total superoxide dismutase activity were increased slightly in WT-NSCs, but decreased in Bmi1+/--NSCs. H2O2 at 10 μM decreased proliferation and self-renewal ability of both genotype NSCs, with greater effect in Bmi1+/-. After treatment with 1 mM NAC, the number and diameter of neurospheres, Brdu incorporation rate, cell viability, T-AOC and total superoxide dismutase activity of Bmi1+/--NSCs were lower than those of WT-NSCs. These results suggest that Bmi1+/--NSCs exhibit normal proliferation and self-renewal due to a slight increase in ROS, but are more vulnerable to changes in redox status.

Non-invasive quantification of the mitochondrial redox state in livers during machine perfusion.

Ischemia reperfusion injury (IRI) is a critical problem in liver transplantation that can lead to life-threatening complications and substantially limit the utilization of livers for transplantation. However, because there are no early diagnostics available, fulminant injury may only become evident post-transplant. Mitochondria play a central role in IRI and are an ideal diagnostic target. During ischemia, changes in the mitochondrial redox state form the first link in the chain of events that lead to IRI. In this study we used resonance Raman spectroscopy to provide a rapid, non-invasive, and label-free diagnostic for quantification of the hepatic mitochondrial redox status. We show this diagnostic can be used to significantly distinguish transplantable versus non-transplantable ischemically injured rat livers during oxygenated machine perfusion and demonstrate spatial differences in the response of mitochondrial redox to ischemia reperfusion. This novel diagnostic may be used in the future to predict the viability of human livers for transplantation and as a tool to better understand the mechanisms of hepatic IRI.