Cross talk of nitric oxide, oxygen radicals, and superoxide dismutase regulates the energy metabolism and cell death and determines the fates of aerobic life

Enterococcus faecalis: implications for host health

The microbiota represents a crucial area of research in maintaining human health due to its potential for uncovering novel biomarkers, therapies, and molecular mechanisms relevant to population identification and experimental model characterization. Among these microorganisms, Enterococcus faecalis, a Gram-positive bacterium found in the gastrointestinal tract of humans and animals, holds particular significance. Strains of this bacterial species have sparked considerable debate in the literature due to their dual nature; they can either be utilized as probiotics in the food industry or demonstrate resistance to antibiotics, potentially leading to severe illness, disability, and death. Given the diverse characteristics of Enterococcus faecalis strains, this review aims to provide a comprehensive understanding of their impact on various systems within the host, including the immunological, cardiovascular, metabolic, and nervous systems. Furthermore, we summarize the bacterium-host interaction characteristics and molecular effects to highlight their targets, features, and overall impact on microbial communities and host health.

Loss of Fer Jeopardizes Metabolic Plasticity and Mitochondrial Homeostasis in Lung and Breast Carcinoma Cells

Metabolic plasticity is a hallmark of the ability of metastatic cancer cells to survive under stressful conditions. The intracellular Fer kinase is a selective constituent of the reprogramed mitochondria and metabolic system of cancer cells. In the current work, we deciphered the modulatory roles of Fer in the reprogrammed metabolic systems of metastatic, lung (H358), non-small cell lung cancer (NSCLC), and breast (MDA-MB-231), triple-negative breast cancer (TNBC), carcinoma cells. We show that H358 cells devoid of Fer (H358ΔFer), strictly depend on glucose for their proliferation and growth, and fail to compensate for glucose withdrawal by oxidizing and metabolizing glutamine. Furthermore, glucose deficiency caused increased reactive oxygen species (ROS) production and induction of a DNA damage response (DDR), accompanied by the onset of apoptosis and attenuated cell-cycle progression. Analysis of mitochondrial function revealed impaired respiratory and electron transport chain (ETC) complex 1 (comp. I) activity in the Fer-deficient H358ΔFer cells. This was manifested by decreased levels of NAD⁺ and ATP and relatively low abundance of tricarboxylic acid (TCA) cycle metabolites. Impaired electron transport chain comp. I activity and dependence on glucose were also confirmed in Fer-deficient, MDA-MB-231ΔFer cells. Although both H358ΔFer and MDA-MB-231ΔFer cells showed a decreased aspartate level, this seemed to be compensated by the predominance of pyrimidines synthesis over the urea cycle progression. Notably, absence of Fer significantly impeded the growth of H358ΔFer and MDA-MB-231ΔFer xenografts in mice provided with a carb-deficient, ketogenic diet. Thus, Fer plays a key role in the sustention of metabolic plasticity of malignant cells. In compliance with this notion, targeting Fer attenuates the progression of H358 and MDA-MB-231 tumors, an effect that is potentiated by a glucose-restrictive diet.

The neuro-immune microenvironment of acupoints-initiation of acupuncture effectiveness

Acupuncture is a centuried and unfading treatment of traditional Chinese medicine, which has been proved to exert curative effects on various disorders. Numerous works have been put in to uncover the effective mechanisms of acupuncture. And the interdependent interaction between acupuncture and acupoint microenvironment is a crucial topic. As a benign minimally invasive stimulation, the insertion and manipulation of needle at acupoint could cause deformation of local connective tissue and secretion of various molecules, such as high mobility group box 1 and ATP. The molecules are secreted into extracellular space and bind to the corresponding receptors thus active NF-κB, MAPK, ERK pathways on mast cells, fibroblasts, keratinocytes, and monocytes/macrophages, among others. This is supposed to trigger following transcription and translation of immune factors and neural active substance, as well as promote the free ion movement (such as Ca²⁺ influx) and the expansion of blood vessels to recruit more immune cells to acupoint. Finally, acupuncture could enhance network connectivity of local microenvironment at acupoints. The earlier mentioned substances further act on a variety of receptors in local nerve endings, transmitting electrical and biochemical signals to the CNS, and giving full play to the acupuncture action. In conclusion, we portrayed a neuro-immune microenvironment network of acupoints that medicates the acupuncture action, and would lay a foundation for the systematic study of the complex network relationship of acupoints in the future.

Production of in vitro bovine embryos supplemented with l-carnitine in different oxygen tensions and the relation to nitric oxide

The aim of this study was to evaluate the production of bovine embryos in vitro when supplemented with l-carnitine for 24 h beginning on day 5 (d 5) under two different oxygen tensions (20% or 5%) and the relationship of nitric oxide (NO) in in vitro culture (IVC) medium to embryo development. Cumulus–oocyte complexes (COC; n = 837) were matured in vitro for 24 h and fertilization was performed for 18 h. Zygotes were cultured in vitro for 9 days after in vitro fertilization in synthetic oviductal fluid (SOF) medium with 5% fetal calf serum. At d 5 the plates were assigned to one of four treatment groups: high (20%) or low (5%) O2 tension either with or without the addition of 3.03 mM l-carnitine (High-Cont, High-Lcar, Low-Cont, Low-Lcar). The concentration of NO in the culture medium was evaluated on d 5, d 6 and d 9. On d 7, parts of the embryos were submitted for evaluation of intracellular lipid droplets. The cleavage rate was similar (P > 0.05) between high and low O2 tension and the blastocyst rate was similar in all conditions evaluated. The hatching rate was higher (P < 0.05) for Low-Cont. The NO concentration was higher at d 9 under low O2 tension (P < 0.1). The addition of 3.03 mM l-carnitine between d 5 and d 6 of IVC was not efficient in reducing cytoplasmic lipid content of bovine embryos. Additionally, IVC at a low oxygen tension without l-carnitine promoted better conditions for embryo development. A higher concentration of NO in medium was observed under low O2 tension.

Nitric oxide in cellular adaptation and disease

Nitric oxide synthases are the major sources of nitric oxide, a critical signaling molecule involved in a wide range of cellular and physiological processes. These enzymes comprise a family of genes that are highly conserved across all eukaryotes. The three family members found in mammals are important for inter- and intra-cellular signaling in tissues that include the nervous system, the vasculature, the gut, skeletal muscle, and the immune system, among others. We summarize major advances in the understanding of biochemical and tissue-specific roles of nitric oxide synthases, with a focus on how these mechanisms enable tissue adaptation and health or dysfunction and disease. We highlight the unique mechanisms and processes of neuronal nitric oxide synthase, or NOS1. This was the first of these enzymes discovered in mammals, and yet much remains to be understood about this highly conserved and complex gene. We provide examples of two areas that will likely be of increasing importance in nitric oxide biology. These include the mechanisms by which these critical enzymes promote adaptation or disease by 1) coordinating communication by diverse cell types within a tissue and 2) directing cellular differentiation/activation decisions processes.

Reduction of oxidative stress a key for enhanced postoperative recovery with fewer complications in esophageal surgery patients: Randomized control trial to investigate therapeutic impact of anesthesia management and usefulness of simple blood test for prediction of high-risk patients

BACKGROUND

Oxidative stress may be an integral determinant of surgical stress severity. We examined whether the preoperative level of derivatives of reactive oxygen metabolites (d-ROMs), an oxidative stress biomarker based on total hydroperoxides in circulating blood, is predictive of increased risk of delayed recovery and complications after surgery, as well as the effects of anesthesia management on postoperative recovery in light of oxidative stress.

METHODS

Patients (American Society of Anesthesiologists physical status I-II) scheduled for a radical esophagectomy (n = 186) were randomly selected to receive inhalational sevoflurane (n = 94) or intravenous propofol (n = 92) anesthesia. Preoperative blood d-ROMs level, as well as pre-and postoperative plasma ferric-reducing ability, were analyzed to assess oxidative stress, with white blood cell (WBC) count, C-reactive protein (CRP) level, incidence of severe postoperative complications, and postoperative recovery process within 30 days after surgery also examined in a double-blind fashion.

RESULTS

Postoperative normalization of WBC and CRP was extended in patients with elevated preoperative d-ROMs [WBC versus d-ROMs: correlation coefficient (r) = 0.58 P < .001; CRP versus d-ROMs: r = 0.46 P < .001]. Receiver operating characteristics analysis of d-ROMs in relation to incidence of severe postoperative complications revealed an optimum d-ROMs threshold value of 410 UCarr and that patients with ≥410 UCarr had a greater risk of complications as compared to those with lower values (odds ratio = 4.7). Plasma ferric-reducing ability was decreased by 61 ± 185 mmol·l (P < .001) after surgery, demonstrating development of surgery-related oxidative stress, the magnitude of which was positively correlated with preoperative d-ROMs level (r = 0.16, P = .043). A comparison of the 2 anesthesia management protocols showed that patients who received propofol, an antioxidant anesthetic, had no postoperative decrease in ferric-reducing ability, lower incidence of severe postoperative complications (7 of 92 versus 18 of 94, P = .030, odds ratio = 0.35), and faster uneventful recovery time (WBC normalization days 7.1 ± 5.2 versus 13.6 ± 10.2, P < .001) as compared to those who received sevoflurane.

CONCLUSIONS

Elevated preoperative blood d-ROMs predicts greater intraoperative oxidative stress and increased postoperative complications with prolonged recovery, thus is useful for identifying high-risk patients for delayed and complicated surgical recovery. Reduction of oxidative stress is vital for enhanced recovery, with control by antioxidants such as propofol a possible solution.

Electroacupuncture prevents endothelial dysfunction induced by ischemia-reperfusion injury via a cyclooxygenase-2-dependent mechanism: A randomized controlled crossover trial

Objective

Exploring clinically effective methods to reduce ischemia-reperfusion (IR) injury in humans is critical. Several drugs have shown protective effects, but studies using other interventions have been rare. Electroacupuncture (EA) has induced similar protection in several animal studies but no study has investigated how the effects could be translated and reproduced in humans. This study aimed to explore the potential effect and mechanisms of EA in IR-induced endothelial dysfunction in humans.

Methods

This is a prospective, randomized, crossover, sham-controlled trial consisting of two protocols. Protocol 1 was a crossover study to investigate the effect of EA on IR-induced endothelial dysfunction. Twenty healthy volunteers were randomly assigned to EA or sham EA (sham). Flow mediated dilation (FMD) of the brachial artery (BA), nitroglycerin-mediated endothelial independent dilation, blood pressure before and after IR were measured. In protocol 2, seven volunteers were administered COX-2 inhibitor celecoxib (200 mg orally twice daily) for five days. After consumption, volunteers underwent FMD before and after IR identical to protocol 1.

Results

In protocol 1, baseline BA diameter, Pre-IR BA diameter and FMD were similar between the two groups (p = NS). After IR, sham group showed significantly blunted FMD (Pre-IR: 11.41 ± 3.10%, Post-IR: 4.49 ± 2.04%, p < 0.001). However, EA protected this blunted FMD (Pre-IR: 10.96 ± 5.30%, Post-IR: 9.47 ± 5.23%, p = NS, p < 0.05 compared with sham EA after IR). In protocol 2, this protective effect was completely abolished by pre-treatment with celecoxib (Pre-IR: 11.05 ± 3.27%; Post-IR: 4.20 ± 1.68%, p = 0.001).

Conclusion

EA may prevent IR-induced endothelial dysfunction via a COX-2 dependent mechanism.

Impact of Cu, Zn-Superoxide Dismutase and Se-Dependent Glutathione Peroxidase-1 Knockouts on Acetaminophen-Induced Cell Death and Related Signaling in Murine Liver

There is increasing evidence showing dual functions of antioxidant enzymes in coping with reactive oxygen species (ROS) versus reactive nitrogen species (RNS). The objective of this study was to compare the impacts of knockout of Cu, Zn-superoxide dismutase (SOD1) and Se-dependent glutathione peroxidase-1 (GPX1) on cell death and related signaling mediated by acetaminophen (APAP), a RNS inducer in liver. Two groups of young adult knockout mice (SOD1−-/– and GPX1−-/–), along with their wild types (WT), were killed 5 hrs after an ip injection of saline or APAP (300 mg/kg body wt). While the WT mice showed more hepatic necrosis and DNA breakage than the GPX1−-/– mice, the SOD1−-/– mice had essentially no positive response compared with their saline-injected controls. The APAP treatment activated liver c-jun N-terminal kinase (JNK) in the WT and GPX1−-/– mice, but not in the SOD1−-/– mice. The APAP-induced changes in other cell death-related signal proteins such as p21, caspase-3, and poly(ADP-ribose) polymerase (PARP) also were obviated in the SOD1−-/– mice. In conclusion, knockout of GPX1 did not potentiate APAP-induced cell death and related signaling, whereas the SOD1 null blocked APAP-induced hepatic JNK phosphorylation and cell death.

Mitochondrial reactive oxygen species (ROS) and ROS-induced ROS release

Byproducts of normal mitochondrial metabolism and homeostasis include the buildup of potentially damaging levels of reactive oxygen species (ROS), Ca(2+), etc., which must be normalized. Evidence suggests that brief mitochondrial permeability transition pore (mPTP) openings play an important physiological role maintaining healthy mitochondria homeostasis. Adaptive and maladaptive responses to redox stress may involve mitochondrial channels such as mPTP and inner membrane anion channel (IMAC). Their activation causes intra- and intermitochondrial redox-environment changes leading to ROS release. This regenerative cycle of mitochondrial ROS formation and release was named ROS-induced ROS release (RIRR). Brief, reversible mPTP opening-associated ROS release apparently constitutes an adaptive housekeeping function by the timely release from mitochondria of accumulated potentially toxic levels of ROS (and Ca(2+)). At higher ROS levels, longer mPTP openings may release a ROS burst leading to destruction of mitochondria, and if propagated from mitochondrion to mitochondrion, of the cell itself. The destructive function of RIRR may serve a physiological role by removal of unwanted cells or damaged mitochondria, or cause the pathological elimination of vital and essential mitochondria and cells. The adaptive release of sufficient ROS into the vicinity of mitochondria may also activate local pools of redox-sensitive enzymes involved in protective signaling pathways that limit ischemic damage to mitochondria and cells in that area. Maladaptive mPTP- or IMAC-related RIRR may also be playing a role in aging. Because the mechanism of mitochondrial RIRR highlights the central role of mitochondria-formed ROS, we discuss all of the known ROS-producing sites (shown in vitro) and their relevance to the mitochondrial ROS production in vivo.

Free Radical Scavenging Properties of Skin and Pulp Extracts of Different Grape Cultivars In Vitro and Attenuation of H2O2-Induced Oxidative Stress in Liver Tissue Ex Vivo

Grapes are the richest source of antioxidants due to the presence of potent bioactive phytochemicals. In this study, the phytochemical contents, scavenging activities and protective role against H2O2-induced oxidative stress in liver tissue ex vivo of four grape (Vitis vinifera) cultivars extracts, namely Flame seedless (black), Kishmish chorni (black with reddish brown), Red globe (red) and Thompson seedless mutant (green), were evaluated. The total phenolics and flavonoids content in pulp or skin fractions of different grape cultivars were in the range of 47.6-310 mg gallic acid equivalent/g fresh weight (fw), and 46.6-733.3 µg catechin equivalent/g fw respectively. The scavenging activities in skin of different grape varieties against 2,2-diphenyl-1-picrylhydrazyl (44-58 %), hydrogen peroxide (15.3-18.6 %), and hydroxyl radicals (50-85 %), were higher than pulp of the corresponding cultivars. These scavenging activities of grape extracts were found to be significantly (p < 0.01) correlated with the levels of total phenols, flavonoids and ascorbic acid. Liver tissues from goat treated with H2O2 (500 μM) showed significantly decreased GSH content by 42.9 % and activities of catalase by 50 % and glutathione reductase by 66.6 %; while increased thiobarbituric acid reactive substances and nitric oxide level by 2.53- and 0.86-fold, respectively, and activity of glutathione S-transferase by 0.96-fold. Grape skin extracts showed the stronger protective activity against H2O2-induced oxidative stress in liver tissue ex vivo, than its pulp of any cultivar; and the Flame seedless (black) cultivar showed the highest potential. In conclusion, our study suggested that the higher antioxidant potential, phytochemical contents and significant scavenging capacities in pulp and skin of grape extracts showed the protective action of grape extracts against H2O2-induced oxidative stress in liver tissue ex vivo.

HBOC vasoactivity: interplay between nitric oxide scavenging and capacity to generate bioactive nitric oxide species

SIGNIFICANCE

Despite many advances in blood substitute research, the development of materials that are effective in maintaining blood volume and oxygen delivery remains a priority for emergency care and trauma. Clinical trials on hemoglobin (Hb)-based oxygen carriers (HBOCs) have not provided information on the mechanism of toxicity, although all commercial formulations have safety concerns. Specifically, it is important to reconcile the different hypotheses of Hb toxicity, such as nitric oxide (NO) depletion and oxidative reactions, to provide a coherent molecular basis for designing a safe HBOC.

RECENT ADVANCES

HBOCs with different sizes often exhibit differences in the degree of HBOC-induced vasoactivity. This has been attributed to differences in the degree of NO scavenging and in the extent of Hb extravasation. Additionally, it is appears that Hb can undergo reactions that compensate for NO scavenging by generating bioactive forms of NO.

CRITICAL ISSUES

Engineering modifications to enhance bioactive NO production can result in diminished oxygen delivery by virtue of increased oxygen affinity. This strategy can prevent the HBOC from fulfilling the intended goal on preserving oxygenation; however, the NO production effects will increase perfusion and oxygen transport.

FUTURE DIRECTIONS

Hb modifications influence NO scavenging and the capacity of certain HBOCs to compensate for NO scavenging through nitrite-mediated reactions that generate bioactive NO. Based on the current understanding of these NO-related factors, possible synthetic strategies are presented that address how HBOC formulations can be prepared that: (i) effectively deliver oxygen, (ii) maintain tissue perfusion, and (iii) limit/reverse underlying inflammation within the vasculature.

Effect of oxygen free radicals and nitric oxide on apoptosis of immune organ induced by selenium deficiency in chickens

Selenium is an essential element with antioxidant roles in immune regulation, but there is little understanding of how Se acts in apoptosis in the immune organs of birds. The aim of study was to evaluate the influence of Se deficiency on oxygen free radicals, NO and apoptosis in immune organ of chickens. 160 1-day-old chickens were randomly assigned to two groups of 80 each and were fed on a low-Se diet (0.032 mg/kg Se) or a control diet (0.282 mg/kg Se), respectively. OFR production in blood was determined on days 30, 45, 60 and 75, respectively. The iNOS-NO system activity in immune organ (thymus, spleen, bursa of fabricius) was identified by NO content and NOS activity assay on days 30, 45, 60 and 75, respectively. Apoptosis was measured by DNA ladder analysis, ultrastructural observations, TdT-mediated dUTP nick end labeling TUNEL assay and flow cytometric analysis of apoptotic DNA. The transcription of factor-associated suicide, caspase-3 mRNA was tested by fluorescence quantitative PCR. The results showed that OFR production, NO and inducible NO synthases (iNOS) activity in the low-Se group were significantly increased (p < 0.05) than in the control group. In addition, apoptosis was observed in chicken immune organ in the low-Se group. The degree and the number of apoptotic cells rose in a time-dependent manner. The expression of Fas and caspase-3 mRNA increased (p < 0.05) than in the control group. It indicated that the oxidative stress and NO played a causative role in the apoptosis of immune tissues induced by selenium deficiency.

Nitric oxide inhibits succinate dehydrogenase-driven oxygen consumption in potato tuber mitochondria in an oxygen tension-independent manner

NO (nitric oxide) is described as an inhibitor of plant and mammalian respiratory chains owing to its high affinity for COX (cytochrome c oxidase), which hinders the reduction of oxygen to water. In the present study we show that in plant mitochondria NO may interfere with other respiratory complexes as well. We analysed oxygen consumption supported by complex I and/or complex II and/or external NADH dehydrogenase in Percoll-isolated potato tuber (Solanum tuberosum) mitochondria. When mitochondrial respiration was stimulated by succinate, adding the NO donors SNAP (S-nitroso-N-acetyl-DL-penicillamine) or DETA-NONOate caused a 70% reduction in oxygen consumption rate in state 3 (stimulated with 1 mM of ADP). This inhibition was followed by a significant increase in the Km value of SDH (succinate dehydrogenase) for succinate (Km of 0.77±0.19 to 34.3±5.9 mM, in the presence of NO). When mitochondrial respiration was stimulated by external NADH dehydrogenase or complex I, NO had no effect on respiration. NO itself and DETA-NONOate had similar effects to SNAP. No significant inhibition of respiration was observed in the absence of ADP. More importantly, SNAP inhibited PTM (potato tuber mitochondria) respiration independently of oxygen tensions, indicating a different kinetic mechanism from that observed in mammalian mitochondria. We also observed, in an FAD reduction assay, that SNAP blocked the intrinsic SDH electron flow in much the same way as TTFA (thenoyltrifluoroacetone), a non-competitive SDH inhibitor. We suggest that NO inhibits SDH in its ubiquinone site or its Fe–S centres. These data indicate that SDH has an alternative site of NO action in plant mitochondria.

Oxidative stress in MeHg-induced neurotoxicity

Methylmercury (MeHg) is an environmental toxicant that leads to long-lasting neurological and developmental deficits in animals and humans. Although the molecular mechanisms mediating MeHg-induced neurotoxicity are not completely understood, several lines of evidence indicate that oxidative stress represents a critical event related to the neurotoxic effects elicited by this toxicant. The objective of this review is to summarize and discuss data from experimental and epidemiological studies that have been important in clarifying the molecular events which mediate MeHg-induced oxidative damage and, consequently, toxicity. Although unanswered questions remain, the electrophilic properties of MeHg and its ability to oxidize thiols have been reported to play decisive roles to the oxidative consequences observed after MeHg exposure. However, a close examination of the relationship between low levels of MeHg necessary to induce oxidative stress and the high amounts of sulfhydryl-containing antioxidants in mammalian cells (e.g., glutathione) have led to the hypothesis that nucleophilic groups with extremely high affinities for MeHg (e.g., selenols) might represent primary targets in MeHg-induced oxidative stress. Indeed, the inhibition of antioxidant selenoproteins during MeHg poisoning in experimental animals has corroborated this hypothesis. The levels of different reactive species (superoxide anion, hydrogen peroxide and nitric oxide) have been reported to be increased in MeHg-exposed systems, and the mechanisms concerning these increments seem to involve a complex sequence of cascading molecular events, such as mitochondrial dysfunction, excitotoxicity, intracellular calcium dyshomeostasis and decreased antioxidant capacity. This review also discusses potential therapeutic strategies to counteract MeHg-induced toxicity and oxidative stress, emphasizing the use of organic selenocompounds, which generally present higher affinity for MeHg when compared to the classically studied agents.

Cytokine toxicity in insulin-producing cells is mediated by nitro-oxidative stress-induced hydroxyl radical formation in mitochondria

Although nitric oxide (NO) and oxidative stress both contribute to proinflammatory cytokine toxicity in pancreatic β-cells during type 1 diabetes mellitus (T1DM) development, the interactions between NO and reactive oxygen species (ROS) in cytokine-mediated β-cell death have not been clarified. Exposure of insulin-producing RINm5F cells to IL-1β generated NO, while exposure to a combination of IL-1β, TNF-α, and IFN-γ, which simulates T1DM conditions, generated both NO and ROS. In theory, two reactions between NO and ROS are possible, one with the superoxide radical yielding peroxynitrite, and the other with hydrogen peroxide (H(2)O(2)) yielding hydroxyl radicals. Results of the present work exclude peroxynitrite involvement in cytokine toxicity to β-cells because its generation did not correlate with the toxic action of cytokines. On the other hand, we show that H(2)O(2), produced upon exposure of insulin-producing cell clones and primary rat islet cells to cytokines almost exclusively in the mitochondria, reacted in the presence of trace metal (Fe(++)) with NO forming highly toxic hydroxyl radicals, thus explaining the severe toxicity that causes apoptotic β-cell death. Expression of the H(2)O(2)-inactivating enzyme catalase in mitochondria protected against cytokine toxicity by preventing hydroxyl radical formation. We therefore conclude that proinflammatory cytokine-mediated β-cell death is due to nitro-oxidative stress-mediated hydroxyl radical formation in the mitochondria.

Effects of exposure of rats to periodic versus continuous hyperoxia on antioxidant potentials and free radical production in relation to ultrastructural changes in myocardial cells

The purpose of the present study was to examine the effects of periodic hyperoxia training (PHT) and/or continuous exposure to hyperoxia (HP) on free radical (FR) levels and biological antioxidant potentials (BAPs) in relation to ultrastructural pathological changes in myocytes. Thirty adult male rats were randomly assigned to three groups: control (C), HP, or PHT. HP rats were continuously subjected to atmospheres containing 100% O2 for 48 h, whereas PHT animals breathed 100% O2 for 30-min periods three times daily over a 3-week period. Ultrastructural examination of isolated myocytes from the HP rats showed that swelled mitochondria with constricted and proliferated cristae of the inner membrane were associated with disarrangement of myofibrils as well as the loss of I-banding. Heart tissue supernatant analyses also provided evidence of significantly higher FR levels in samples from the HP rats as compared with values noted with materials from control and PHT rats. In contrast, BAP was significantly higher in the samples from rats in the PHT group as compared levels associated with the control or the HP hosts. As HP resulted in mitochondrial pathological alterations in the cristae, this implied the induction of a myocardium oxidative stress (MOS). As PHT enhanced BAP, it may be concluded that PHT likely enhances an apparent antioxidant response that did not permit FR to build up. Because PHT elevations would be expected to help lower FR levels, it would seem that periodic hyperoxia training might induce an adaptive resistance in the heart against the formation of potentially toxicologically deleterious reactive metabolite species.

Induction of oxidative cell damage by photo-treatment with zincmetaN-methylpyridylporphyrin

We have previously reported that isomeric Zn(II) N-methylpyridylporphyrins (ZnTM-2(3,4)-PyP4 + ) can act as photosensitizers with efficacy comparable to that of hematoporphyrin derivative (HpD) in preventing cell proliferation and causing cell death in vitro. To better understand the biochemical basis of this activity, the effects of photo-activated ZnTM-3-PyP4 + on GSH/GSSG ratio, lipid peroxidation, membrane permeability, oxidative DNA damage, and the activities of SOD, catalase, glutathione reductase, and glutathione peroxidase were evaluated. Light exposure of ZnTM-3-PyP4 + -treated colon adenocarcinoma cells caused a wide spectrum of oxidative damage including depletion of GSH, inactivation of glutathione reductase and glutathione peroxidase, oxidative DNA damage and peroxidation of membrane lipids. Cell staining with Hoechst-33342 showed morphological changes consistent with both necrotic and apoptotic death sequences, depending upon the presence of oxygen.

Effect of Nitric Oxide on the Oxygen Metabolism and Growth of E. faecalis

Gastro-intestinal mucosal cells have a potent mechanism to eliminate a variety of pathogens using enzymes that generate reactive oxygen species and/or nitric oxide (NO). However, a large number of bacteria survive in the intestine of human subjects. Enterococcus faecalis (E. faecalis) is a Gram-positive bacterium that survives not only in the intestinal lumen but also within macrophages generating NO. It has been reported that E. faecalis generated the superoxide radical (O₂⁻). To elucidate the role of O₂⁻ and NO in the mechanism for the pathogen surviving in the intestine and macrophages, we studied the role and metabolism of O₂⁻ and NO in and around E. faecalis. Kinetic analysis revealed that E. faecalis generated 0.5 µmol O₂⁻/min/10⁸ cells in a glucose-dependent manner as determined using the cytochrome c reduction method. The presence of NOC12, an NO donor, strongly inhibited the growth of E. faecalis without affecting in the oxygen consumption. However, the growth rate of NOC12-pretreated E. faecalis in NO-free medium was similar to that of untreated cells. Western blotting analysis revealed that the NOC12-treated E. faecalis revealed a large amount of nitrotyrosine-posititive proteins; the amounts of the modified proteins were higher in cytosol than in membranes. These observations suggested that O₂⁻ generated by E. faecalis reacted with NO to form peroxinitrite (ONOO⁻) that preferentially nitrated tyrosyl residues in cytosolic proteins, thereby reversibly inhibited cellular growth. Since E. faecalis survives even within macrophages expressing NO synthase, similar metabolism of O₂⁻ and NO may occur in and around phagocytized macrophages.

Open abdominal surgery increases intraoperative oxidative stress: can it be prevented?

BACKGROUND

The involvement of reactive oxygen species early in the development of surgical stress and injury is highly suspected but has not been confirmed. Medical approaches to manage this type of oxidative stress are unknown.

METHODS

We measured levels of blood hydroperoxides as an index of oxidative injury of cellular components, as well as plasma ferric-reducing ability as an index of total antioxidant potential, during sigmoidectomy under four conditions: open sigmoidectomy with sevoflurane anesthesia, laparoscopic sigmoidectomy with sevoflurane anesthesia, open sigmoidectomy with propofol anesthesia, and laparoscopic sigmoidectomy with propofol anesthesia.

RESULTS

Ferric-reducing ability decreased significantly during surgery for the open sigmoidectomy with sevoflurane anesthesia, by 387 +/- 153 mmol/L, though the hydroperoxides level did not change, showing that oxidative stress increases in surgical patients. However, its toxicity may not be high enough to injure cellular components, since hydroperoxides, which are typical oxidized products of cellular components, did not increase. There were no changes in the hydroperoxides level or the ferric-reducing ability for the laparoscopic sigmoidectomy with sevoflurane anesthesia, indicating that this procedure does not increase surgical oxidative stress. Only hydroperoxides decreased significantly at the end of surgery for the open sigmoidectomy with propofol anesthesia and laparoscopic sigmoidectomy with propofol anesthesia, by 120 +/- 73 and 144 +/- 107 UCarr (1 UCarr corresponds to 0.8 mg/L H(2)O(2)), respectively.

CONCLUSIONS

It seems certain that open abdominal surgery of the intestinal tract increases intraoperative oxidative stress. A laparoscopic procedure was not associated with oxidative stress, and propofol anesthesia reduced it by apparently functioning as an antioxidant.

Effect of increasing maternal body mass index on oxidative and nitrative stress in the human placenta

Maternal obesity is an increasing problem in obstetrics associated with adverse pregnancy outcomes and delivery complications. As an inflammatory state, where elevated levels of pro-inflammatory cytokines are found, obesity can lead to the increased incidence of oxidative and nitrative stress. These stresses may result in protein oxidation and protein nitration respectively, which are post- translational covalent modifications that can modify the structure and subsequently alter the function of a protein. The objective of this study was to examine whether placental oxidative and nitrative stress increase with increasing maternal body mass index. Placental tissue was collected from three groups of patients categorized as lean, overweight and obese. The presence of nitrotyrosine residues, a marker of nitrative stress, and antioxidant enzymes, as markers of oxidative stress, were assessed by immunohistochemistry, Western blot and ELISA. Protein carbonyl formation, a specific measure of protein oxidation, was measured by OxyBlot kit. Nitrotyrosine residues were increased in obese compared to lean and overweight groups although localization was unaltered across the three groups. Superoxide dismutase enzyme expression, localization and activity was unaltered between the groups. Protein carbonyl formation was greater in the lean compared to the overweight individuals. This study demonstrates that with increasing maternal body mass index there is an increase in placental nitrative stress. There does not appear to be a corresponding increase in oxidative stress and indeed we demonstrate some evidence of a decrease in oxidative effects in these placenta samples. Potentially the formation of peroxynitrite may be consuming reactive oxygen species and reducing oxidative stress. There may be a shift in the balance between nitrative and oxidative stress, which may be a protective mechanism for the placenta.

Effectiveness of acupuncture, special dressings and simple, low-adherence dressings for healing venous leg ulcers in primary healthcare: study protocol for a cluster-randomized open-labeled trial

Background

Venous leg ulcers constitute a chronic recurring complaint that affects 1.0–1.3% of the adult population at some time in life, and which corresponds to approximately 75% of all chronic ulcers of the leg. Multilayer compression bandaging is, at present, the only treatment that has been proved to be effective in treating this type of ulcer. There is no consensus, however, about the dressings that may be applied, beneath the compression, to promote the healing of this type of ulcer, as there does not seem to be any added benefit from using special dressings rather than simple, low-adherence ones. As well as analgesia, acupuncture provokes peripheral vasodilation, in skin and muscles – which has been demonstrated both experimentally and in clinical practice – probably due to the axon reflex, among other mechanisms. The aim of the present study is to measure the effectiveness and cost of compression treatment for venous leg ulcers combined with special dressings, in comparison with low-adherence ones and acupuncture.

Methods/design

Cluster-randomized open-labeled trial, at 15 primary healthcare clinics in the Sevilla-Sur Healthcare District, with a control group treated with compression bandaging and low-adherence dressings; the experiment will consist, on the one hand, of the compression treatment applied in combination with special dressings (Treatment 1), and on the other, the compression treatment applied in association with low-adherence dressings, together with acupuncture (Treatment 2).

Discussion

The results will be measured and recorded in terms of the median time elapsed until complete healing of the ulcer, and the rate of complete healing at 3 months after beginning the treatment. An economic analysis will also be made.

This study, carried out in the context of real clinical practice, will provide information for decision-taking concerning the effectiveness of special dressings. Moreover, for the first time a high-quality study will evaluate the effectiveness of acupuncture in the process of healing venous leg ulcers.

Trial registration

Current Controlled Trials ISRCTN26438275.

l-carnitine and its propionate: improvement of endothelial function in SHR through superoxide dismutase-dependent mechanisms

To clarify the mechanism underlying the antioxidant properties of l-carnitine (LC) and propionyl-l-carnitine (PLC) on spontaneously hypertensive (SHR) and normotensive WKY, animals were treated with either PLC or LC (200 mg kg(- 1)). Aorta was dissected and contraction to (R)-( - )-phenylephrine (Phe) and relaxation to carbachol (CCh) were assessed in the presence or not of the NO synthase (NOS) inhibitor, l-NAME. [image omitted] production was evaluated by lucigenin-enhanced chemiluminescence and its participation on relaxation was observed after incubation with superoxide dismutase (SOD) plus catalase. Protein expressions of eNOS, Cu/Zn-SOD and Mn-SOD were studied by western blot. Both LC and PLC treatments improved endothelial function of SHR through increasing NO participation and decreasing [image omitted] probably involving higher Cu/Zn-SOD expression. PLC treatment augmented eNOS expression in SHR. Surprisingly, LC increased [image omitted] produced by aorta from WKY and thus diminished NO and damaged endothelial function. Conversely, PLC did not affect CCh-induced relaxation in WKY. These results demonstrate that LC and PLC prevent endothelial dysfunction in SHR through an antioxidant effect.

Evidence of enhanced non-enzymatic generation of nitric oxide on the skin surface of acupuncture points: An innovative approach in humans

The present study quantified total nitrate and nitrite (NOx-) collected from the skin surface along acupuncture points (acupoints) and determined whether non-enzymatic reduction of nitrate by bacteria is involved in chemical generation of nitric oxide (NO) on acupoints. A small plastic tube (0.5 x 7 cm) cut in half lengthwise was taped to the forearm or leg in 50 healthy volunteers. NO-collecting solutions with NO-scavenging compounds, hemoglobin or 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide, was placed inside the tubing attached to the skin surface for 20 min. The concentrations of NOx- in the collected samples were quantified by using chemiluminescence. NOx- concentration was significantly enhanced in four acupoints on the pericardium meridian and in two acupoints on the bladder meridian compared with those collected on non-meridian control areas. The time intervals of NOx- levels were significantly higher at the first 20 min of acupoint collection, but the concentrations were similar among the study groups collected at 20-40, 40-60, and 60-80 min. NOx- concentrations and numbers of bacteria colonies detected on the skin surface were markedly reduced by pretreatment of skin with sodium hypochlorite compared to water treatment. This is the first evidence showing that NO has been successfully quantified on skin acupoints by a non-invasive device in humans. We conclude that NO is physiologically released from the skin surface with a higher level at acupoints, and that the non-enzymatic reduction of nitrate by bacteria is involved in chemical generation of NO on skin acupoints in addition to l-arginine-derived NO synthesis.

Acupuncture enhances generation of nitric oxide and increases local circulation

Although it is widely used, the mechanisms and effects of acupuncture on pain are not completely understood. Recently, increased nitric oxide (NO) synthase activity has been found in meridians and acupoints. Because NO is a key regulator of local circulation, and because change in circulation can affect the development and persistence of pain, we propose that acupuncture might regulate NO levels. We studied the effects of acupuncture on local NO levels and circulation in a randomized, double-blind, crossover study with 20 volunteers, each of whom underwent one session each of real and noninvasive sham acupuncture in a single hand and forearm with a 1-wk interval between treatments. NO concentration in the plasma from the acupunctured arm was significantly increased by 2.8 +/- 1.5 micromol/L at 5 min and 2.5 +/- 1.4 micromol/L at 60 min after acupuncture. Blood flow in palmar subcutaneous tissue of the acupunctured arm also increased, and this correlated with the NO increase. These changes were not observed in noninvasive sham-acupunctured hands and forearms. In conclusion, acupuncture increases the NO level in treated regions and thereby increases local circulation. These regulatory effects might contribute to pain relief provided by acupuncture.

l-Carnitine suppresses the onset of neuromuscular degeneration and increases the life span of mice with familial amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal disease caused by progressive degeneration of motor neurons in the spinal cord and motor cortex. Although the etiology of ALS remains unknown, a mutation of the gene encoding Cu,Zn-superoxide dismutase (SOD1) has been reported in 20% of familial cases of ALS (FALS). Transgenic mice that overexpress a mutated human SOD1 exhibit a phenotype and pathology similar to those observed in patients with FALS. Mitochondrial abnormality has been reported in patients with ALS and in animal models of FALS. We recently reported that L-carnitine, an essential cofactor for the beta-oxidation of long-chain fatty acids, effectively inhibits various types of mitochondrial injury and apoptosis both in vitro and in vivo. The present study demonstrates that oral administration of L-carnitine prior to disease onset significantly delayed the onset of signs of disease (log-rank P=0.0008), delayed deterioration of motor activity, and extended life span (log-rank P=0.0001) in transgenic mice carrying a human SOD1 gene with a G93A mutation (Tg). More importantly, subcutaneous injection of L-carnitine increased the life span of Tg mice (46% increase in male, 60% increase in female) even when given after the appearance of signs of disease.

L-carnitine inhibits hypoglycemia-induced brain damage in the rat

Hypoglycemia sometimes occurs in patients with diabetes mellitus who receive excessive doses of insulin. Severe hypoglycemia has been known to induce mitochondrial swelling followed by neuronal death in the brain. Since L-carnitine effectively preserves mitochondrial function in various cells both in vitro and in vivo, we investigated its effects on the neuronal damage induced by hypoglycemic insult in male Wistar rats. Animals were given L-carnitine-containing water (0.1%) for 1 week and then received insulin (20 U/kg, i.p.) to induce hypoglycemia. Although L-carnitine did not affect the mortality of animals that developed hypoglycemic shock, it improved the cognitive function of the survived animals as assessed by the Morris water-maze test. L-carnitine effectively inhibited the increase in oxidized glutathione and mitochondrial dysfunction in the hippocampus and prevented neuronal injury. L-carnitine also inhibited the decrease in mitochondrial membrane potential and the generation of reactive oxygen species in hippocampal neuronal cells cultured in glucose-deprived medium. These results suggest that L-carnitine prevents hypoglycemia-induced neuronal damage in the hippocampus, presumably by preserving mitochondrial functions. Thus, L-carnitine may have therapeutic potential in patients with hypoglycemia induced by insulin overdose.

L-Carnitine halts apoptosis and myelosuppression induced by carboplatin in rat bone marrow cell cultures (BMC)

Carboplatin (CP), a second generation platinum compound, is effective against various types of cancers, producing less nephrotoxicity and ototoxicity but more myelotoxicity than cisplatinum. CP-myelosuppression is the rate-limiting step of its clinical use. Prevention of CP-myelosuppression is a major target in the field of chemotherapy. Therefore, the present study investigates the use of L-carnitine (LCR)-an antioxidant, cardioprotective, neuroprotective, and immunostimulant nontoxic natural compound-to protect against CP-induced myelosuppression. The viability of BMC was studied using a trypan blue exclusion technique following incubation with CP and/or LCR as a function of time and concentration. Apoptosis was tested for by detecting the amount of DNA fragmentation and the visualization of DNA ladders upon gel electrophoresis. Bone marrow progenitor cell function was examined by colony forming unit assay. Cellular contents of glutathione (GSH) and malondialdehyde (MDA) were also estimated. Results revealed that LC50 of CP is 4.7 mM and the highest safe concentration of LCR is 5 mM. Co-exposure of LCR+CP rescued BMC viability by 37% compared to the CP-treated cultures. The LCR halts CP-induced apoptosis and it significantly improves the function of the bone marrow progenitors by increasing the number of colony-forming units as a response to granulocyte/macrophage colony stimulating factors. Finally, LCR restores CP-induced GSH depletion and prevents MDA elevation in BMC. In summary, the results suggest that LCR is able to protect against CP-induced myelosuppression, which suggests its use as an adjuvant therapy. This finding merits further investigation into the mechanism(s) of such protection as well as its interaction with CP antitumor activity.

The role of the mitochondrion in trauma and shock

The mitochondrion of the eukaryotic cell is well known as a "power plant" whose energy is made available via the high-energy phosphate bonds of ATP. This indispensable and superbly adapted organelle appears to have originated as an endosymbiotic bacterium rather than as a eukaryotic creation per se. However, under the dangerous conditions of trauma and shock, the mitochondrion can become destabilized and harm its host cell in a variety of ways. These contrary traits may be, in part, vestiges from the bacterial origins of mitochondria. The mitochondrion can respond to the stress of trauma and shock by opening pores that leak contents into the host cell's cytoplasm, an event that can trigger programmed cell death or necrosis. In addition, the enormous oxygen consumption by mitochondria presents a two-edged sword in that a deranged mitochondrion can produce reactive oxygen species that damage genes and gene products, inflicting considerable harm to the mitochondrion and its host cell. However, although trauma and shock can cause the mitochondrion to wreak havoc in many ways, an adjuvant intervention with exogenous ATP-MgCl2 after trauma and shock appears useful for reducing cell and organ damage under those conditions.

Reactive oxygen and nitrogen species: Friends or foes?

Chemical and physiological functions of molecular oxygen and reactive oxygen species (ROS) and existing equilibrium between pools of pro-oxidants and anti-oxidants providing steady state ROS level vital for normal mitochondrial and cell functioning are reviewed. The presence of intracellular oxygen and ROS sensors is postulated and few candidates for this role are suggested. Possible involvement of ROS in the process of fragmentation of mitochondrial reticulum made of long mitochondrial filaments serving in the cell as "electric cables", as well as the role of ROS in apoptosis and programmed mitochondrial destruction (mitoptosis) are reviewed. The critical role of ROS in destructive processes under ischemia/reoxygenation and ischemic preconditioning is discussed. Mitochondrial permeability transition gets special consideration as a possible component of the apoptotic cascade, resulting in excessive "ROS-induced ROS release".

HIV-1 accessory protein Vpr inhibits the effect of insulin on the Foxo subfamily of forkhead transcription factors by interfering with their binding to 14-3-3 proteins: potential clinical implications regarding the insulin resistance of HIV-1-infected patients

HIV-1 accessory protein Vpr arrests host cells at the G2/M phase of the cell cycle by interacting with members of the protein family 14-3-3, which regulate the activities of "partner" molecules by binding to their phosphorylated serine or threonine residues and changing their intracellular localization and/or stability. Vpr does this by facilitating the association of 14-3-3 to its partner protein Cdc25C, independent of the latter's phosphorylation status. Here we report that the same viral protein interfered with and altered the activity of another 14-3-3 partner molecule, Foxo3a, a subtype of the forkhead transcription factors, by inhibiting its association with 14-3-3. Foxo3a's transcriptional activity is normally suppressed by insulin-induced translocation of this protein from the nucleus into the cytoplasm. Vpr inhibited the ability of insulin or its downstream protein kinase Akt to change the intracellular localization of Foxo3a preferentially to the cytoplasm. This HIV-1 protein also interfered with insulin-induced coprecipitation of 14-3-3 and Foxo3a in vivo and antagonized the negative effect of insulin on Foxo3a-induced transactivation of a FOXO-responsive promoter. Moreover, Vpr antagonized insulin-induced suppression of the mRNA expression of the glucose 6-phosphatase, manganese superoxide dismutase, and sterol carrier protein 2 genes, which are known targets of insulin and FOXO, in HepG2 cells. These findings indicate that Vpr interferes with the suppressive effects of insulin on FOXO-mediated transcription of target genes via 14-3-3. Vpr thus may contribute to the tissue-selective insulin resistance often observed in HIV-1-infected individuals.