Oxygen-dependent microbial killing by phagocytes (second of two parts)

Oxytocin and oxygen: the evolution of a solution to the ‘stress of life’

Oxytocin (OT) and the OT receptor occupy essential roles in our current understanding of mammalian evolution, survival, sociality and reproduction. This narrative review examines the hypothesis that many functions attributed to OT can be traced back to conditions on early Earth, including challenges associated with managing life in the presence of oxygen and other basic elements, including sulfur. OT regulates oxidative stress and inflammation especially through effects on the mitochondria. A related nonapeptide, vasopressin, as well as molecules in the hypothalamic–pituitary–adrenal axis, including the corticotropin-releasing hormone family of molecules, have a broad set of functions that interact with OT. Interactions among these molecules have roles in the causes and consequence of social behaviour and the management of threat, fear and stress. Here, we discuss emerging evidence suggesting that unique properties of the OT system allowed vertebrates, and especially mammals, to manage over-reactivity to the ‘side effects’ of oxygen, including inflammation, oxidation and free radicals, while also supporting high levels of sociality and a perception of safety.

This article is part of the theme issue ‘Interplays between oxytocin and other neuromodulators in shaping complex social behaviours’.

Hyperbaric oxygen therapy in malignant otitis externa: A systematic review of the literature

OBJECTIVE

To review the role of adjuvant hyperbaric oxygen therapy (HBOT) in the treatment of malignant otitis externa (MOE).

DATA SOURCES

PubMed, Scopus, Web of Science, Science Direct, and Cochrane Library were searched for the following concepts: "hyperbaric oxygen" and "malignant or necrotizing otitis externa."

METHODS

Studies were included if they contained (1) patients with reported evidence of MOE, (2) employment of adjuvant HBOT, (3) details on patients' medical condition, and (4) documented survival outcomes. Extracted information included patient demographics, underlying medical conditions, infectious etiology, signs and symptoms, medical and surgical treatments, duration of medical treatment, mean follow up time, HBOT setting, number of HBOT sessions, complications, survival rate, and all-cause mortality.

RESULTS

A total of 16 studies comprising 58 patients (mean age 68.0 years) were included. Diabetes was present in 94.7% of cases and Pseudomonas spp (64.3%) was the most common infectious agent. Cranial nerve VII was involved in 55.2% of cases. Overall, the disease cure rate with adjuvant HBOT was 91.4% and all-cause mortality was 8.6%. Among those who had cranial nerve VII involvement, 72.0% had return of function and 93.8% of them survived.

CONCLUSION

HBOT may be an effective treatment option for refractory or advanced MOE but its efficacy remains unproven due to lack of strong scientific evidence. However, its therapeutic value should not be underestimated given good results and few adverse events reported in this study.

Investigating the Response of Human Neutrophils to Hydrophilic and Hydrophobic Micro-Rough Titanium Surfaces

Various treatments have been used to change both the topography and chemistry of titanium surfaces, aiming to enhance tissue response and reduce healing times of endosseous implants. Most studies to date focused on bone healing around dental implants occurring later during the healing cascade. However, the impact of the initial inflammatory response in the surgical wound site on the success and healing time of dental implants is crucial for implant integration and success, yet it is still poorly understood. The purpose of this study was to investigate the effect of titanium surface hydrophilicity on the response of human neutrophils by monitoring oxygen radical production, which was measured as chemiluminescence activity. Materials and Methods: Neutrophils were isolated from human donors’ blood buffy coats using the double sucrose gradient method. Neutrophils were exposed to both hydrophilic and hydrophobic titanium surfaces with identical topographies in the presence and absence of human serum. This resulted in six experimental groups including two different implant surfaces, with and without exposure to human serum, and two control groups including an active control with cells alone and a passive control with no cells. Two samples from each group were fixed and analyzed by SEM. Comparisons between surface treatments for differences in chemiluminescence values were performed using analysis of variance ANOVA. Results and Conclusion: In the absence of exposure to serum, there was no significant difference noted between the reaction of neutrophils to hydrophilic and hydrophobic surfaces. However, there was a significant reduction in the mean and active chemiluminescence activity of neutrophils to serum-coated hydrophilic titanium surfaces than to serum-coated hydrophobic titanium surfaces. This suggests that surface hydrophilicity promotes enhanced adsorption of serum proteins, which leads to decreased provocation of initial immune cells and reduction of local oxygen radical production during wound healing. This can help explain the faster osseointegration demonstrated by hydrophilic titanium implants.

The Role of Melanin in Fungal Pathogenesis for Animal Hosts

Melanins are a class of pigments that are ubiquitous throughout biology. They play incredibly diverse and important roles ranging from radiation protection to immune defense, camouflage, and virulence. Fungi have evolved to use melanin to be able to persist in the environment and within organisms. Fungal melanins are often located within the cell well and are able to neutralize reactive oxygen species and other radicals, defend against UV radiation, bind and sequester non-specific peptides and compounds, and produce a physical barrier that defends the cell. For this reason, melanized fungi are often well-suited to be human pathogens-melanin allows fungi to neutralize the microbicidal oxidative bursts of our innate immune system, bind and inactivate to antimicrobial peptides and enzymes, sequester antifungal pharmaceuticals, and create a shield to block immune recognition of the fungus. Due to the importance and pervasiveness of melanin in fungal virulence, mammalian immune systems have evolved antifungal strategies that involve directly detecting and binding to fungal melanins. Such strategies include the use of melanin-specific antibody responses and C-type lectins like the newly discovered melanin-specific MelLec receptor.

Crucial Role of Nucleic Acid Sensing via Endosomal Toll-Like Receptors for the Defense of Streptococcus pyogenes in vitro and in vivo

Streptococcus pyogenes is a major human pathogen causing a variety of diseases ranging from common pharyngitis to life-threatening soft tissue infections and sepsis. Microbial nucleic acids, especially bacterial RNA, have recently been recognized as a major group of pathogen-associated molecular patterns (PAMPs) involved in the detection of Streptococcus pyogenes via endosomal Toll-like receptors (TLRs) in vitro. However, the individual contribution and cooperation between TLRs as well as cell-type and strain specific differences in dependency on nucleic acid detection during S. pyogenes infection in vitro have not been clarified in detail. Moreover, the role of particularly bacterial RNA for the defense of S. pyogenes infection in vivo remains poorly defined. In this study, we report that in all investigated innate immune cells involved in the resolution of bacterial infections, including murine macrophages, dendritic cells and neutrophils, recognition of S. pyogenes strain ATCC12344 is almost completely dependent on nucleic acid sensing via endosomal TLRs at lower MOIs, whereas at higher MOIs, detection via TLR2 plays an additional, yet redundant role. We further demonstrate that different S. pyogenes strains display a considerable inter-strain variability with respect to their nucleic acid dependent recognition. Moreover, TLR13-dependent recognition of S. pyogenes RNA is largely non-redundant in bone marrow-derived macrophages (BMDMs), but less relevant in neutrophils and bone marrow-derived myeloid dendritic cells (BMDCs) for the induction of an innate immune response in vitro. In vivo, we show that a loss of nucleic acid sensing blunts early recognition of S. pyogenes, leading to a reduced local containment of the bacterial infection with subsequent pronounced systemic inflammation at later time points. Thus, our results argue for a crucial role of nucleic acid sensing via endosomal TLRs in defense of S. pyogenes infection both in vitro and in vivo.

Interleukin-1β Protects Neurons against Oxidant-Induced Injury via the Promotion of Astrocyte Glutathione Production

Interleukin-1β (IL-1β), a key cytokine that drives neuroinflammation in the Central Nervous System (CNS), is enhanced in many neurological diseases/disorders. Although IL-1β contributes to and/or sustains pathophysiological processes in the CNS, we recently demonstrated that IL-1β can protect cortical astrocytes from oxidant injury in a glutathione (GSH)-dependent manner. To test whether IL-1β could similarly protect neurons against oxidant stress, near pure neuronal cultures or mixed cortical cell cultures containing neurons and astrocytes were exposed to the organic peroxide, tert-butyl hydroperoxide (t-BOOH), following treatment with IL-1β or its vehicle. Neurons and astrocytes in mixed cultures, but not pure neurons, were significantly protected from the toxicity of t-BOOH following treatment with IL-1β in association with enhanced GSH production/release. IL-1β failed to increase the GSH levels or to provide protection against t-BOOH toxicity in chimeric mixed cultures consisting of IL-1R1^+/+ neurons plated on top of IL-1R1^−/− astrocytes. The attenuation of GSH release via block of multidrug resistance-associated protein 1 (MRP1) transport also abrogated the protective effect of IL-1β. These protective effects were not strictly an in vitro phenomenon as we found an increased striatal vulnerability to 3-nitropropionic acid-mediated oxidative stress in IL-1R1 null mice. Overall, our data indicate that IL-1β protects neurons against oxidant injury and that this likely occurs in a non-cell-autonomous manner that relies on an increase in astrocyte GSH production and release.

Klotho dysfunction: A pathway linking the aging process to bipolar disorder?

AIM

Although accelerated aging profile has been described in bipolar disorder (BD), the biology linking BD and aging is still largely unknown. Reduced levels and/or activity of a protein named Klotho is associated with decreased life span, premature aging and occurrence of age-related diseases. Therefore, this study was designed to evaluate plasma levels of Klotho in BD patients and controls.

METHODS

Forty patients with type 1 BD and 30 controls were enrolled in this study. After clinical evaluation, peripheral blood samples were drawn and plasma levels of Klotho were measured using enzyme-linked immunosorbent assay.

RESULTS

Patients with BD and controls presented similar age and sex distribution. The mean ± SD length of illness was 24.00 ± 12.75 years. BD patients presented increased frequency of clinical comorbidities in comparison with controls, mainly arterial hypertension, diabetes mellitus, and hypothyroidism. Both patients with BD in remission and in mania exhibited increased plasma levels of Klotho in comparison with controls. There was no significant difference between patients in mania and patients in remission regarding the levels of Klotho.

CONCLUSION

Klotho-related pathway is altered in BD. Contrary to our original hypothesis, our sample of patients with BD presented increased plasma levels of Klotho in comparison with controls. Elevated levels of Klotho in long-term BD patients may be associated with the disorder progression. Further studies are needed to better understand the role of Klotho in BD and other mood disorders.

Prevention of Periprosthetic Joint Infection: Examining the Recent Guidelines

BACKGROUND

The global rise in infectious disease has led the Center for Disease Control and Prevention and the World Health Organization to release new guidelines for the prevention of surgical site infection.

METHODS

In this article, we summarize current recommendations based on level of evidence, review unresolved and unaddressed issues, and supplement them with new literature.

RESULTS

Although the guidelines discuss major issues in reducing surgical site infection, many questions remain unanswered.

CONCLUSION

These guidelines will hopefully help in setting a standard of care based on best evidence available and focus investigators on areas where evidence is lacking.

New Insights in Oxidant Biology in Asthma

Research over the past 30 years has identified mechanistic biochemical oxidation pathways that contribute to asthma pathophysiology. Redox imbalance is present in asthma and strongly linked to the pathobiology of airflow obstruction, airway hyperreactivity, and remodeling. High levels of reactive oxygen species, reactive nitrogen species, and oxidatively modified proteins in the lung, blood, and urine provide conclusive evidence for pathologic oxidation in asthma. Concurrent loss of antioxidants, such as superoxide dismutases and catalase, is attributed to redox modifications of the enzymes, and further amplifies the oxidative injury in the airway. The presence of high levels of urine bromotyrosine, an oxidation product of eosinophil peroxidase, identifies activated eosinophils, and shows promise for use as a noninvasive biomarker of poor asthma control.

Streptococcus pneumoniae Senses a Human-like Sialic Acid Profile via the Response Regulator CiaR

Streptococcus pneumoniae is a human-adapted pathogen that encounters terminally sialylated glycoconjugates and free sialic acid (Sia) in the airways. Upon scavenging by the bacterial sialidase NanA, Sias serve as carbon sources for the bacteria. Unlike most animals in which cytidine-monophosphate-N-acetylneuraminic acid hydroxylase (CMAH) converts Sia N-acetylneuraminic acid (Neu5Ac) into N-glycolylneuraminic acid (Neu5Gc), humans have an inactive CMAH, causing an absence of Neu5Gc and excess Neu5Ac. We find that pneumococcal challenge in Cmah(-/-) mice leads to heightened bacterial loads, virulence, and NanA expression. In vitro, NanA is upregulated in response to Neu5Ac compared with Neu5Gc, a process controlled by the two-component response regulator CiaR and requiring Sia uptake by the transporter SatABC. Additionally, compared with Neu5Gc, Neu5Ac increases pneumococcal resistance to antimicrobial reactive oxygen species in a CiaR-dependent manner. Thus, S. pneumoniae senses and responds to Neu5Ac, leading to CiaR activation and increased virulence and potentially explaining the greater susceptibility in humans.

Smoking, chronic wound healing, and implications for evidence-based practice

Chronic wounds are rising in prevalence and creating significant socioeconomic burdens for patients and healthcare systems worldwide. Therefore, it is now more important than ever that clinicians follow evidence-based guidelines for wound care when developing personalized treatment plans for their patients with chronic wounds. Evidence-based guidelines for treating venous leg ulcers, diabetic foot ulcers, and pressure ulcers, the 3 main categories of chronic wounds, focus primarily on biologic therapies. However, there are also evidence-based guidelines for treating behavioral risks to poor healing, such as smoking, which should be incorporated into treatment plans when appropriate. The purpose of this article was to review the mechanisms through which smoking adversely impacts the wound healing process, and propose strategies for incorporating evidence-based guidelines for treating tobacco dependence into treatment plans for patients with chronic wounds who smoke.

Identification of a myeloperoxidase-like ortholog from rock bream (Oplegnathus fasciatus), deciphering its transcriptional responses to induced pathogen stress

Myeloperoxidases (MPOs) are heme-linked oxidative stress-generating enzymes found abundantly in azurophilic granules of polymorphonuclear neutrophils. Mature MPOs act as potent antimicrobial agents by producing hypohalous acids using hydrogen peroxide and halide ions as substrates. These acids can readily oxidize reactive groups of biomolecules on invading microbes. In this study, we identified and characterized a homolog of MPO from rock bream (Oplegnathus fasciatus), designated as RbMPO. We analyzed the RbMPO gene for its basal expression level in physiologically important tissues and for transcriptional changes under different pathogenic stress conditions. The complete coding sequence of RbMPO consisted of 2652 nucleotides encoding an 884 amino acid sequence with a predicted molecular mass of 99.7 kDa. Our in silico analysis confirmed the typical MPO domain arrangement in RbMPO, including the propeptide, large chain and heavy chain, along with the heme peroxidase signature. Intriguingly, a C1q domain was also identified in the C-terminal region of the derived amino acid sequence. Most of the known functionally important residues of MPOs are found to be well conserved in RbMPO, showing a close evolutionary relationship with other teleostan MPOs, particularly with that of mandarin fish. RbMPO exhibited a ubiquitous basal expression in physiologically relevant tissues, with particularly high expression levels in blood cells. Basal transcript levels of RbMPO in gill and spleen tissues were found to change upon different pathogen or pathogen-derived mitogen stimulation, with detectable inductive responses. Together, these data suggest the potential involvement of RbMPO in the innate immune response in rock bream.

Intra-operative tissue oxygen tension is increased by local insufflation of humidified-warm CO2 during open abdominal surgery in a rat model

INTRODUCTION

Maintenance of high tissue oxygenation (PtO2) is recommended during surgery because PtO2 is highly predictive of surgical site infection and colonic anastomotic leakage. However, surgical site perfusion is often sub-optimal, creating an obstructive hurdle for traditional, systemically applied therapies to maintain or increase surgical site PtO2. This research tested the hypothesis that insufflation of humidified-warm CO2 into the abdominal cavity would increase sub-peritoneal PtO2 during open abdominal surgery.

MATERIALS AND METHODS

15 Wistar rats underwent laparotomy under general anesthesia. Three sets of randomized cross-over experiments were conducted in which the abdominal cavity was subjected to alternating exposure to 1) humidified-warm CO2 & ambient air; 2) humidified-warm CO2 & dry-cold CO2; and 3) dry-cold CO2 & ambient air. Sub-peritoneal PtO2 and tissue temperature were measured with a polarographic oxygen probe.

RESULTS

Upon insufflation of humidified-warm CO2, PtO2 increased by 29.8 mmHg (SD 13.3; p<0.001), or 96.6% (SD 51.9), and tissue temperature by 3.0°C (SD 1.7 p<0.001), in comparison with exposure to ambient air. Smaller, but significant, increases in PtO2 were seen in experiments 2 and 3. Tissue temperature decreased upon exposure to dry-cold CO2 compared with ambient air (-1.4°C, SD 0.5, p = 0.001).

CONCLUSIONS

In a rat model, insufflation of humidified-warm CO2 into the abdominal cavity during open abdominal surgery causes an immediate and potentially clinically significant increase in PtO2. The effect is an additive result of the delivery of CO2 and avoidance of evaporative cooling via the delivery of the CO2 gas humidified at body temperature.

A review of herbal medicines in wound healing

Herbs have been integral to both traditional and non-traditional forms of medicine dating back at least 5000 years. The enduring popularity of herbal medicines may be explained by the perception that herbs cause minimal unwanted side effects. More recently, scientists increasingly rely on modern scientific methods and evidence-based medicine to prove efficacy of herbal medicines and focus on better understanding of mechanisms of their action. However, information concerning quantitative human health benefits of herbal medicines is still rare or dispersed, limiting their proper valuation. Preparations from traditional medicinal plants are often used for wound healing purposes covering a broad area of different skin-related diseases. Herbal medicines in wound management involve disinfection, debridement, and provision of a suitable environment for aiding the natural course of healing. Here we report on 22 plants used as wound healing agents in traditional medicine around the world. The aim of this review is therefore to review herbal medicines, which pose great potential for effective treatment of minor wounds.

MutT from the fish pathogen Aliivibrio salmonicida is a cold-active nucleotide-pool sanitization enzyme with unexpectedly high thermostability

Upon infection by pathogenic bacteria, production of reactive oxygen species (ROS) is part of the host organism's first line of defence. ROS damage a number of macromolecules, and in order to withstand such a harsh environment, the bacteria need to have well-functioning ROS scavenging and repair systems. Herein, MutT is an important nucleotide-pool sanitization enzyme, which degrades 8-oxo-dGTP and thus prevents it from being incorporated into DNA. In this context, we have performed a comparative biochemical and structural analysis of MutT from the fish pathogen Aliivibrio salmonicida (AsMutT) and the human pathogen Vibrio cholerae (VcMutT), in order to analyse their function as nucleotide sanitization enzymes and also determine possible cold-adapted properties of AsMutT. The biochemical characterisation revealed that both enzymes possess activity towards the 8-oxo-dGTP substrate, and that AsMutT has a higher catalytic efficiency than VcMutT at all temperatures studied. Calculations based on the biochemical data also revealed a lower activation energy (E a) for AsMutT compared to VcMutT, and differential scanning calorimetry experiments showed that AsMutT displayed an unexpected higher melting temperature (T m) value than VcMutT. A comparative analysis of the crystal structure of VcMutT, determined to 2.42 Å resolution, and homology models of AsMutT indicate that three unique Gly residues in loops of VcMutT, and additional long range ion-pairs in AsMutT could explain the difference in temperature stability of the two enzymes. We conclude that AsMutT is a stable, cold-active enzyme with high catalytic efficiency and reduced E a, compared to the mesophilic VcMutT.

A dual-radioisotope hybrid whole-body micro-positron emission tomography/computed tomography system reveals functional heterogeneity and early local and systemic changes following targeted radiation to the murine caudal skeleton

The purpose of this study was to develop a longitudinal non-invasive functional imaging method using a dual-radioisotope hybrid micro-positron emission tomography/computed tomography (PET/CT) scanner in order to assess both the skeletal metabolic heterogeneity and the effect of localized radiation that models therapeutic cancer treatment on marrow and bone metabolism. Skeletally mature BALB/c female mice were given clinically relevant local radiation (16 Gy) to the hind limbs on day 0. Micro-PET/CT acquisition was performed serially for the same mice on days -5 and +2 with FDG and days -4 and +3 with NaF. Serum levels of pro-inflammatory cytokines were measured. Significant differences (p < 0.0001) in marrow metabolism (measured by FDG) and bone metabolism (measured by NaF) were observed among bones before radiation, which demonstrates functional heterogeneity in the marrow and mineralized bone throughout the skeleton. Radiation significantly (p < 0.0001) decreased FDG uptake but increased NaF uptake (p = 0.0314) in both irradiated and non-irradiated bones at early time points. An increase in IL-6 was observed with a significant abscopal (distant) effect on marrow and bone metabolic function. Radiation significantly decreased circulating IGF-1 (p < 0.01). Non-invasive longitudinal imaging with dual-radioisotope micro-PET/CT is feasible to investigate simultaneous changes in marrow and bone metabolic function at local and distant skeletal sites in response to focused radiation injury. Distinct local and remote changes may be affected by several cytokines activated early after local radiation exposure. This approach has the potential for longer-term studies to clarify the effects of radiation on marrow and bone.

Insight into mucinous colorectal carcinoma: clues from etiology

The prognostic impact of mucinous carcinoma (MC) in colorectal cancer (CRC) has been subject to debate ever since the introduction of the classification of tumors according to their histological differentiation. MC is a distinct clinical and pathological entity within the spectrum of CRC and accounts for approximately 10-15 % of cases. Factors involved in MC development have not been completely understood, but clinical observations may lead to a better insight into the etiology of MC. In this article, we provide an in-depth review of the literature regarding etiological aspects of MC. We show that there are worldwide differences in the prevalence of MC, with low rates in Asian countries and higher rates in the western world. Moreover, MC is more commonly diagnosed in patients suffering from inflammatory bowel diseases or Lynch syndrome and an increased rate of MC is observed in patients with radiotherapy-induced CRCs. These findings are suggestive of a different oncogenic development. Identification of conditions that are associated with MC generates insight into the etiological pathways leading to the development of this special subtype.

Bang-bang model for regulation of local blood flow

The classical model of metabolic regulation of blood flow in muscle tissue implies the maintenance of basal tone in arterioles of resting muscle and their dilation in response to exercise and/or tissue hypoxia via the evoked production of vasodilator metabolites by myocytes. A century-long effort to identify specific metabolites responsible for explaining active and reactive hyperemia has not been successful. Furthermore, the metabolic theory is not compatible with new knowledge on the role of physiological radicals (e.g., nitric oxide, NO, and superoxide anion, O2 (-) ) in the regulation of microvascular tone. We propose a model of regulation in which muscle contraction and active hyperemia are considered the physiologically normal state. We employ the "bang-bang" or "on/off" regulatory model which makes use of a threshold and hysteresis; a float valve to control the water level in a tank is a common example of this type of regulation. Active bang-bang regulation comes into effect when the supply of oxygen and glucose exceeds the demand, leading to activation of membrane NADPH oxidase, release of O2 (-) into the interstitial space and subsequent neutralization of the interstitial NO. Switching arterioles on/off when local blood flow crosses the threshold is realized by a local cell circuit with the properties of a bang-bang controller, determined by its threshold, hysteresis, and dead-band. This model provides a clear and unambiguous interpretation of the mechanism to balance tissue demand with a sufficient supply of nutrients and oxygen.

Perioperative supplemental oxygen to reduce surgical site infection after open fixation of high-risk fractures: a randomized controlled pilot trial

BACKGROUND

Higher concentrations of fraction of inspired oxygen (FIO2) have been shown to be associated with lower risk for surgical site infection in multiple studies outside the domain of orthopedic surgery. We evaluated the efficacy of high FIO2 administered during the perioperative period to reduce the rate of surgical site infection after open fixation of lower-extremity fractures at high risk of infection.

METHODS

We conducted a randomized controlled, parallel design, double-blind study. Patients sustaining high-energy tibial plateau, tibial pilon, and calcaneus fractures treated in a staged fashion were selected for enrollment because these injuries are associated with high risk of infection. The study population included 222 patients with 235 fractures. Consenting patients were randomized by random number sequence to either the treatment or the control group. Treatment group patients received 80% FIO2 intraoperatively and for 2 hours afterward. Control group patients received 30% FIO2 during the same period. Surgeons, patients, and personnel who performed wound assessments were blinded to group assignment. The primary outcome measure was surgical site infection as defined by the Centers for Disease Control criteria for postoperative wound infection.

RESULTS

The overall rates of postoperative surgical site infection were 12% (14 of 119 fractures) in the treatment group and 16% (19 of 116 fractures) in the control group (p = 0.31). Multivariate analysis, accounting for risk factors for infection, yielded the closest to a statistically significant reduction in the odds of infection with treatment (odds ratio, 0.54; p = 0.17). No treatment-associated events were observed.

CONCLUSION

Use of a high concentration of FIO2 during the perioperative period is safe and shows a trend toward reduction of surgical site infection in patients undergoing open operative fixation of high-energy traumatic lower-extremity fractures. Further study in a larger patient population is indicated.

LEVEL OF EVIDENCE

Therapeutic study, level III.

Antioxidants as potential therapeutics for neuropsychiatric disorders

Oxidative stress has been implicated in the pathophysiology of many neuropsychiatric disorders such as schizophrenia, bipolar disorder, major depression etc. Both genetic and non-genetic factors have been found to cause increased cellular levels of reactive oxygen species beyond the capacity of antioxidant defense mechanism in patients of psychiatric disorders. These factors trigger oxidative cellular damage to lipids, proteins and DNA, leading to abnormal neural growth and differentiation. Therefore, novel therapeutic strategies such as supplementation with antioxidants can be effective for long-term treatment management of neuropsychiatric disorders. The use of antioxidants and PUFAs as supplements in the treatment of neuropsychiatric disorders has provided some promising results. At the same time, one should be cautious with the use of antioxidants since excessive antioxidants could dangerously interfere with some of the protective functions of reactive oxygen species. The present article will give an overview of the potential strategies and outcomes of using antioxidants as therapeutics in psychiatric disorders.

Hyperbaric oxygen therapy as adjunctive treatment of diabetic foot ulcers

The widespread use of HBO as an adjunctive treatment of diabetic foot ulcers has been founded on weak scientific evidence, but the consistency in positive outcomes in trials evaluating HBO on ulcer healing is noteworthy, not least as these results are in concert with data from in vitro and physiologic studies supporting the theoretical framework of HBO reversing hypoxia-induced abnormality. The long-term ulcer-healing rates of the nonrandomized controlled studies before the recent study by Margolis and colleagues, 77% with HBO versus 25% with standard treatment, are in concert with 1-year follow-up data from the 2 double-blind RCTs, 54% versus 25%. These 2 trials have put the use of HBO on firmer ground, but several issues, including health economics, developing robust selection criteria for treatment, optimizing treatment protocols, and identifying standards for when to start and stop treatment, remain to be elucidated. Not least, outcomes from further high-quality studies are needed. At present, HBO may be used as an adjunctive therapy in a select group of patients with diabetic foot ulcers that are difficult to heal.

STAT5 triggers BCR-ABL1 mutation by mediating ROS production in chronic myeloid leukaemia

We recently reported that chronic myeloid leukaemia (CML) patients harbour high levels of STAT5 when they progress to advanced phases of disease. Advanced disease is characterized by an increased incidence of BCR-ABL1 mutations. We now describe a highly significant correlation between STAT5 expression and the incidence of BCR-ABL1 mutations in primary CML. Forced expression of STAT5 in murine BCR-ABL1 transformed cells sufficed to enhance the production of reactive oxygen species (ROS) and to trigger DNA damage. STAT5-mediated ROS production is independent of JAK2 but requires concomitant BCR-ABL1 signalling as forced STAT5 expression in untransformed BCR-ABL1 negative cells has no impact on ROS levels. Only within the context of a BCR-ABL1 positive cell does STAT5 transcriptionally regulate a target gene or set of genes that causes the enhanced ROS production. Our study suggests the existence of a feed-forward loop accelerating disease progression, in which BCR-ABL1 enhances its own mutation rate in a STAT5-ROS dependent manner. This model explains the increased occurrence of inhibitor-resistant BCR-ABL1 mutations in advanced disease stages driven and characterized by high STAT5 expression.

Orchestration of inflammation and adaptive immunity in Borrelia burgdorferi-induced arthritis by neutrophil-activating protein A

OBJECTIVE

Lyme arthritis (LA) is characterized by infiltration of inflammatory cells, mainly neutrophils (polymorphonuclear cells [PMNs]) and T cells, into the joints. This study was undertaken to evaluate the role of the neutrophil-activating protein A (NapA) of Borrelia burgdorferi in eliciting inflammation and in driving the adaptive immune response.

METHODS

Levels of NapA, interferon-γ (IFNγ), interleukin-17 (IL-17), and T cell-attracting chemokines were assessed by enzyme-linked immunosorbent assay in synovial fluid from patients with LA. The profile of T cells recruited into the synovia of patients with LA was defined by fluorescence-activated cell sorting analysis. NapA was intraarticularly injected into rat knees, and the cells recruited in synovia were characterized. The role of NapA in recruiting immune cells was confirmed by chemotaxis assays using a Transwell system.

RESULTS

NapA, IFNγ, IL-17, CCL2, CCL20, and CXCL10 accumulated in synovial fluid from patients with LA. Accordingly, T cells obtained from these patients produced IFNγ or IL-17, but notably, some produced both cytokines. NapA promoted neutrophil and T lymphocyte recruitment both in vitro and in vivo. Interestingly, the infiltration of T cells not only resulted from the chemotactic activity of NapA but also relied on the chemokines produced by PMNs exposed to NapA.

CONCLUSION

We provide evidence that NapA functions as one of the main bacterial products involved in the pathogenesis of LA. Accordingly, we show that, at very early stages of LA, NapA accumulates and, in turn, orchestrates the recruitment of inflammatory cells into the joint cavity. Thereafter, with the contribution of recruited cells, NapA promotes the infiltration of T cells producing IL-17 and/or IFNγ.

Hyperbaric oxygen therapy as adjunctive treatment for diabetic foot ulcers

Hyperbaric oxygen therapy (HBOT) has been suggested to improve healing of hard-to-heal diabetic foot ulcers. Although the wide use of HBOT as a treatment for diabetic foot ulcers has been founded on weak scientific ground, 2 well-designed randomized, double-blind, placebo-controlled studies have in recent years put HBOT on firmer ground as treatment for diabetic patients with chronic foot ulcers. The recognition of inclusion criteria in these studies may help identify a select group of diabetic patients with hard-to-heal ulcers who might benefit from HBOT. In this review, we discuss the rationale behind the use of HBOT, its clinical application, and possible treatment complications.

Inflammation and Barrett's carcinogenesis

Barrett's esophagus (BE) is one of the most common premalignant lesions in which normal squamous epithelium of the esophagus is replaced by metaplastic columnar epithelium. Esophageal adenocarcinoma (EA) develops through progression from BE to low- and high-grade dysplasia (LGD/HGD) and to adenocarcinoma. It is widely accepted that inflammation can increase cancer risk, promoting tumor progression. Therefore, inflammation is regarded as the seventh hallmark of cancer. In recent years, the inflammation-cancer connection of Barrett's carcinogenesis has been intensively studied, unraveling genetic abnormalities. Besides genetic alterations, inflammation is also epigenetically linked to loss of protein expression through transcriptional silencing via promoter methylation. Key mediators linking inflammation and Barrett's carcinogenesis include reactive oxygen species (ROS), NFκB, inflammatory cytokines, prostaglandins, and specific microRNAs (miRNAs). Therefore, the decipherment of molecular pathways that contain these and novel inflammatory key mediators is of major importance for diagnosis, therapy, and prognosis. The detailed elucidation of the signaling molecules involved in Barrett's carcinogenesis will be important for the development of pharmaceutical inhibitors. We herein give an overview of the current knowledge of the inflammation-mediated genetic and epigenetic alterations involved in Barrett's carcinogenesis. We highlight the role of oxidative stress and deregulated DNA damage checkpoints besides the NFκB pathway.

Comparison of tissue oxygen saturation in ovariohysterectomized dogs recovering on room air versus nasal oxygen insufflation

OBJECTIVE

To compare tissue oxygen saturation in ovariohysterectomized dogs recovering postoperatively on room air versus nasal oxygen insufflation.

DESIGN

Prospective clinical study.

SETTING

University teaching hospital.

ANIMALS

Twenty dogs undergoing ovariohysterectomy.

INTERVENTIONS

Dogs were randomized to breathe either room air or 100 mL/kg/min of nasal oxygen insufflation for 2 hours postoperatively. Tissue oxygen saturation (StO(2)) was evaluated at 2 mm and 20 mm lateral to the surgical incision, as well as in the inguinal region using a noninvasive tissue oximeter.

MEASUREMENTS AND MAIN RESULTS

In dogs recovered on nasal oxygen insufflation (n = 10), tissue oxygen saturation was significantly higher--20 mm from the surgical site (88.44 ± 2.50%, P = 0.02) and in the inguinal region (83.56 ± 1.91%, P = 0.032)-- compared to dogs recovered on room air (n = 10, 79.11% ± 2.50 and 77.12% ± 1.91, respectively).

CONCLUSIONS

In ovariohysterectomized dogs, oxygen supplementation for 2 hours postoperatively improves tissue oxygen saturation 20 mm adjacent to the linea alba and in the inguinal region. Oxygen supplementation in postoperative dogs is an inexpensive and easily applicable method to improve tissue oxygen saturation.

Hyperbaric oxygen therapy as treatment of diabetic foot ulcers

Hyperbaric oxygen therapy (HBO) could be described as a short-term, high-dose oxygen inhalation and diffusion therapy, delivered systemically through airways and blood, achieved by having the patient breathing concentrated oxygen at a pressure higher than 1 absolute atmosphere. In clinical practice, monoplace or multiplace hyperbaric chambers are used to achieve this. Treatment is usually given as daily 90- to 120-min-long HBO sessions at pressures between 2.0 and 2.5 absolute atmosphere, aiming for 30-40 treatment sessions. The use of HBO as treatment of diabetic foot ulcers has been founded on weak scientific ground, although the outcomes from previous studies are in concert with the conclusions from preclinical studies and supports the theoretical framework of HBO reversing hypoxia-induced pathology. Two well-designed randomized double-blind trials have put HBO on firmer ground and may justify adjunctive HBO treatment to a selected group of patients with nonhealing diabetic foot ulcers. Some health economic studies suggest potential cost effectiveness, but these studies are limited by deficient primary clinical data and should be interpreted with caution. Several issues remain to be addressed, such as developing robust criteria to improve treatment protocols, determining which patients are likely to benefit, and when to start and stop treatment.

Molecular Crosstalk between Integrins and Cadherins: Do Reactive Oxygen Species Set the Talk?

The coordinate modulation of the cellular functions of cadherins and integrins plays an essential role in fundamental physiological and pathological processes, including morphogenesis, tissue differentiation and renewal, wound healing, immune surveillance, inflammatory response, tumor progression, and metastasis. However, the molecular mechanisms underlying the fine-tuned functional communication between cadherins and integrins are still elusive. This paper focuses on recent findings towards the involvement of reactive oxygen species (ROS) in the regulation of cell adhesion and signal transduction functions of integrins and cadherins, pointing to ROS as emerging strong candidates for modulating the molecular crosstalk between cell-matrix and cell-cell adhesion receptors.

The Interplay between ROS and Ras GTPases: Physiological and Pathological Implications

The members of the RasGTPase superfamily are involved in various signaling networks responsible for fundamental cellular processes. Their activity is determined by their guanine nucleotide-bound state. Recent evidence indicates that some of these proteins may be regulated by redox agents. Reactive oxygen species (ROSs) and reactive nitrogen species (RNSs) have been historically considered pathological agents which can react with and damage many biological macromolecules including DNA, proteins, and lipids. However, a growing number of reports have suggested that the intracellular production of ROS is tightly regulated and that these redox agents serve as signaling molecules being involved in a variety of cell signaling pathways. Numerous observations have suggested that some Ras GTPases appear to regulate ROS production and that oxidants function as effector molecules for the small GTPases, thus contributing to their overall biological function. Thus, redox agents may act both as upstream regulators and as downstream effectors of Ras GTPases. Here we discuss current understanding concerning mechanisms and physiopathological implications of the interplay between GTPases and redox agents.

Antimicrobial actions of reactive oxygen species

Everything should be as simple as it can be, but not simpler.

—Attributed to Albert Einstein (1)

Reactive oxygen species (ROS) are produced by host phagocytes and exert antimicrobial actions against a broad range of pathogens. The observable antimicrobial actions of ROS are highly dependent on experimental conditions. This perspective reviews recent controversies regarding ROS in Salmonella-phagocyte interactions and attempts to reconcile conflicting observations from different laboratories.

Supplemental oxygen for the prevention of postcesarean infectious morbidity: a randomized controlled trial

OBJECTIVE

The purpose of this study was to investigate whether supplemental oxygen during and for 2 hours after cesarean delivery reduces the incidence of postcesarean infectious morbidity.

STUDY DESIGN

We conducted a randomized, controlled trial from 2008-2010. Women who underwent cesarean delivery were randomly assigned to receive either 2 L of oxygen by nasal cannula during cesarean delivery only (standard care) or 10 L of oxygen by nonrebreather mask (intervention group) during and for 2 hours after cesarean delivery. Women who underwent scheduled or intrapartum cesarean delivery were eligible and were observed for 1 month after the procedure. The primary composite outcome was maternal infectious morbidity, which included endometritis and wound infection.

RESULTS

Five hundred eighty-five women were included in the final analysis. Infectious morbidity occurred in 8.8% of patients in the standard care group and in 12.2% of patients in the supplemental oxygen group. There was no significant difference in the rate of infectious morbidity between the standard care and intervention groups (relative risk, 1.4; 95% confidence interval, 0.9-2.3).

CONCLUSION

Supplemental oxygen does not reduce the rate of postcesarean delivery infectious morbidity, including endometritis and wound infection.

Hyperoxia may be beneficial

The current practice of mechanical ventilation comprises the use of the least inspiratory O2 fraction associated with an arterial O2 tension of 55 to 80 mm Hg or an arterial hemoglobin O2 saturation of 88% to 95%. Early goal-directed therapy for septic shock, however, attempts to balance O2 delivery and demand by optimizing cardiac function and hemoglobin concentration, without making use of hyperoxia. Clearly, it has been well-established for more than a century that long-term exposure to pure O2 results in pulmonary and, under hyperbaric conditions, central nervous O2 toxicity. Nevertheless, several arguments support the use of ventilation with 100% O2 as a supportive measure during the first 12 to 24 hrs of septic shock. In contrast to patients without lung disease undergoing anesthesia, ventilation with 100% O2 does not worsen intrapulmonary shunt under conditions of hyperinflammation, particularly when low tidal volume-high positive end-expiratory pressure ventilation is used. In healthy volunteers and experimental animals, exposure to hyperoxia may cause pulmonary inflammation, enhanced oxidative stress, and tissue apoptosis. This, however, requires long-term exposure or injurious tidal volumes. In contrast, within the timeframe of a perioperative administration, direct O2 toxicity only plays a negligible role. Pure O2 ventilation induces peripheral vasoconstriction and thus may counteract shock-induced hypotension and reduce vasopressor requirements. Furthermore, in experimental animals, a redistribution of cardiac output toward the kidney and the hepato-splanchnic organs was observed. Hyperoxia not only reverses the anesthesia-related impairment of the host defense but also is an antibiotic. In fact, perioperative hyperoxia significantly reduced wound infections, and this effect was directly related to the tissue O2 tension. Therefore, we advocate mechanical ventilation with 100% O2 during the first 12 to 24 hrs of septic shock. However, controlled clinical trials are mandatory to test the safety and efficacy of this approach.

Anthocyanin extracted from black soybean reduces prostate weight and promotes apoptosis in the prostatic hyperplasia-induced rat model

Anthocyanin is a natural plant pigment and potent antioxidant. This study was designed to investigate the effects of anthocyanin extracted from black soybeans on a rat model of benign prostatic hyperplasia (BPH), a disease associated with the geriatric population. Thirty male rats were divided into five experimental groups: a control group, a BPH-induced group, and three BPH-induced groups that received oral doses of anthocyanin (40, 80, and 160 mg/kg). Prostate hyperplasia was induced by the administration of testosterone propionate for 4 weeks. Following BPH induction, the anthocyanin-treated groups received the compound for 4 weeks. After anthocyanin treatment, the prostates from the rats in all groups were removed, weighed, and subjected to histological examination. Apoptosis in the prostates was measured by the TUNEL assay. The mean prostate weight for the control animals was 674.17 ± 28.24 mg, whereas the BPH-induced rats had a mean prostate weight of 1098.33 ± 131.31 mg. The mean prostate weights for the rats receiving 40, 80, and 160 mg/kg anthocyanin were 323.00 ± 22.41, 324.00 ± 26.80, and 617.50 ± 31.08 mg, respectively. The average prostate weight in the BPH-induced group was significantly higher than in the control group (p < 0.05), whereas the prostate weights in the anthocyanin-administered groups were significantly lower than in the BPH-induced group (p < 0.05). Injected testosterone led to prostatic hyperplasia as observed histologically, but anthocyanin administration helped to prevent this change. Apoptotic body counts were significantly higher in groups receiving anthocyanin than in the BPH-induced group (p < 0.05). These results suggest that anthocyanin may be effective in decreasing the volume and suppressing the proliferation of the prostate. Further studies are needed to better understand the mechanisms and actions of anthocyanin, and these studies may lead to the clinical application of anthocyanin in treating BPH.

Investigation of mechanism(s) of DNA damage induced by 4-monochlorobiphenyl (PCB3) metabolites

4-Monochlorobiphenyl (PCB3) is readily converted by xenobiotic-metabolizing enzymes to dihydroxy-metabolites and quinones. The PCB3 hydroquinone (PCB3-HQ; 2-(4'-chlorophenyl)-1,4-hydroquinone) induces chromosome loss in Chinese Hamster V79 cells, whereas the para-quinone (PCB3-pQ; 2-(4'-chlorophenyl)-1,4-benzoquinone) very efficiently induces gene mutations and chromosome breaks. Apparently, each of these two metabolites, which are a redox pair, has a different spectrum of genotoxic effects due to different, metabolite-specific mechanisms. We hypothesized that the HQ requires enzymatic activation by peroxidases with the formation of reactive oxygen species (ROS) as the ultimate genotoxin, whereas the pQ reacts directly with nucleophilic sites in DNA and/or proteins. To examine this hypothesis, we employed two cell lines with different myeloperoxidase (MPO) activities, MPO-rich HL-60 and MPO-deficient Jurkat cells, and measured cytotoxicity, DNA damage (COMET assay), MPO activity, intracellular levels of reactive oxygen species (ROS) and intracellular free -SH groups (monochlorobimane assay, MCB) and free GSH contents (enzyme recycling method) after treatment with PCB3-HQ and PCB3-pQ. We also examined the modulation of these effects by normal/low temperature, pre-treatment with an MPO inhibitor (succinylacetone, SA), or GSH depletion. PCB3-p-Q increased intracellular ROS levels and induced DNA damage in both HL-60 and Jurkat cells at 37°C and 6°C, indicating a direct, MPO-independent mode of activity. It also strongly reduced intracellular free -SH groups and GSH levels in normal and GSH-depleted cells. Thus the ROS increase could be caused by reduced protection by GSH or non-enzymatic autoxidation of the resulting PCB3-HQ-GSH adduct. PCB3-HQ did not produce a significant reduction of intracellular GSH in HL-60 cells and reduced intracellular free -SH groups only at the highest concentration tested in GSH depleted cells. Moreover, PCB3-HQ induced DNA damage and ROS production only at 37 °C in HL-60 cells, not at 6 °C or in Jurkat cells at either temperature; no significant DNA damage and ROS production was observed in HL-60 cells at 37 °C if MPO activity was inhibited by SA. These studies show that the effects of PCB3-HQ are enzyme dependent, i.e. PCB3-HQ is oxidized by MPO in HL-60 cells with the generation of ROS and induction of DNA damage. However, this is not the case with the PCB3-pQ, which may produce DNA damage by the reactivity of the quinone with the DNA or nuclear proteins, or possibly by indirectly increasing intracellular ROS levels by GSH depletion. These different modes of action explain not only the different types of genotoxicity observed previously, but also suggest different organ specificity of these genotoxins.

Difficulties in managing the surgical patient who is morbidly obese

Managing patients who are morbidly obese in the intensive care unit is associated with a variety of problems uncommonly experienced with the those who are not morbidly obese. Clinicians experience a myriad of unique problems and circumstances, from the need for special beds and lifts to unusual and unknown volumes of distribution resulting in unclear drug dosing. This review examines several issues including sedation, invasive monitoring, venous thromboembolism prophylaxis, surgical infections, nutritional support, and other complications that may be of particular importance to the critically ill patient who is morbidly obese. In many cases, care is altered based on the complicating issues surrounding morbid obesity. In other cases, the presence of obesity suggests no alterations in our routine critical care delivery. A comprehensive review of the literature is undertaken, data are critically considered, and overall opinion is rendered based on the available peer-reviewed literature. In many cases, data are not available that address the specific patient population in question, so related papers (like gastric bypass data) are considered. Many issues do not have definitive answers based on randomized controlled trials, and much is left to treating clinician opinion and local practice patterns. Where good data exist, however, one should consider carefully and individually deviation from the evidence-based approach.

Bone and wound healing in the diabetic patient

Impaired soft tissue regeneration and delayed osseous healing are known complications associated with diabetes mellitus with regard to orthopedic surgery, making the management and treatment of diabetic patients undergoing foot and ankle surgery more complex and difficult. At the moment several options are available to address the known issues that complicate the clinical outcomes in these high-risk patients. Using a multifaceted approach, with close attention to intraoperative and perioperative considerations including modification of surgical technique to supplement fixation, local application of orthobiologics, tight glycemic control, administration of supplementary oxygen, and biophysical stimulation via low-intensity pulsed ultrasound and electrical bone stimulation, the impediments associated with diabetic healing can potentially be overcome, to yield improved clinical results for diabetic patients after acute or elective foot and ankle surgery.

Temperature control and the role of supplemental oxygen

Unrecognized and untreated intraoperative hypothermia remains a common avoidable scenario in the modern operating room. Failure to properly address this seemingly small aspect of the total operative care has been shown to have profound negative patient consequences including increased incidence of postoperative discomfort, surgical bleeding, requirement of allogenic blood transfusion, wound infections, and morbid cardiac events. All of these ultimately lead to longer hospitalizations and higher mortality. To avoid such problems, simple methods can be employed by the surgeon, anesthesiologist, and ancillary personnel to ensure euthermia. Similarly, another effortless method to potentially improve surgical outcomes is the liberal use of supplemental oxygen. Promising preliminary data suggests that high-concentration oxygen during and after surgery may decrease the rate of surgical site infections and gastrointestinal anastomotic failure. The precise role of supplemental oxygen in the perioperative period represents an exciting area of potential research that awaits further validation and analysis. In this article, the authors explore the data regarding both temperature regulation and supplemental oxygen use in an attempt to define further their emerging role in the perioperative care of patients undergoing colorectal surgery.

Redox control of asthma: molecular mechanisms and therapeutic opportunities

An imbalance in reducing and oxidizing (redox) systems favoring a more oxidative environment is present in asthma and linked to the pathophysiology of the defining symptoms and signs including airflow limitation, hyper-reactivity, and airway remodeling. High levels of hydrogen peroxide, nitric oxide ((*)NO), and 15-F(2t)-isoprostane in exhaled breath, and excessive oxidative protein products in lung epithelial lining fluid, peripheral blood, and urine provide abundant evidence for pathologic oxidizing processes in asthma. Parallel studies document loss of reducing potential by nonenzymatic and enzymatic antioxidants. The essential first line antioxidant enzymes superoxide dismutases (SOD) and catalase are reduced in asthma as compared to healthy individuals, with lowest levels in those patients with the most severe asthma. Loss of SOD and catalase activity is related to oxidative modifications of the enzymes, while other antioxidant gene polymorphisms are linked to susceptibility to develop asthma. Monitoring of exhaled (*)NO has entered clinical practice because it is useful to optimize asthma care, and a wide array of other biochemical oxidative and nitrative biomarkers are currently being evaluated for asthma monitoring and phenotyping. Novel therapeutic strategies that target correction of redox abnormalities show promise for the treatment of asthma.

The ozone paradox: ozone is a strong oxidant as well as a medical drug

After five decades characterized by empiricism and several pitfalls, some of the basic mechanisms of action of ozone in pulmonary toxicology and in medicine have been clarified. The present knowledge allows to understand the prolonged inhalation of ozone can be very deleterious first for the lungs and successively for the whole organism. On the other hand, a small ozone dose well calibrated against the potent antioxidant capacity of blood can trigger several useful biochemical mechanisms and reactivate the antioxidant system. In detail, firstly ex vivo and second during the infusion of ozonated blood into the donor, the ozone therapy approach involves blood cells and the endothelium, which by transferring the ozone messengers to billions of cells will generate a therapeutic effect. Thus, in spite of a common prejudice, single ozone doses can be therapeutically used in selected human diseases without any toxicity or side effects. Moreover, the versatility and amplitude of beneficial effect of ozone applications have become evident in orthopedics, cutaneous, and mucosal infections as well as in dentistry.