Exposure time related oxidative action of hyperbaric oxygen in rat brain

Correlation between Time to Hyperbaric Oxygen Therapy and Delayed Neurological Sequelae in Acute Carbon Monoxide Poisoning Patients

Carbon monoxide (CO) is one of the most common causes of intoxication. Delayed neurologic sequelae (DNS) have a major impact on prognosis of CO poisoning patients. Hyperbaric oxygen therapy (HBOT) is widely used to treat DNS. However, there is no consensus regarding the optimal timing of HBOT. This prospective study enrolled patients who visited the hospital from November 2019 to October 2022. The cutoff value for the latency to HBOT after CO exposure was determined, and the area under the receiver operating characteristic curve (AUC) was estimated. In total, 167 patients were divided into non-DNS and DNS groups. The initial Glasgow Coma Scale (GCS) score, CO exposure time, latency to HBOT after CO exposure, median length of hospital stay (p < 0.001) and creatine kinase (p = 0.016) showed significant differences. A GCS score ≤ 9 had an odds ratio (OR) of 5.059 (95% confidence interval [CI]: 1.602-15.976, p = 0.006), and latency to HBOT after CO exposure ≥ 200 min had an OR of 18.971 (95% CI: 4.310-83.508, p < 0.001). The AUC was 0.8235 (95% CI: 0.7504-0.8966). A GCS score ≤ 9 and latency to HBOT ≥ 200 min may be significant risk factors for DNS.

An overview of hyperbaric oxygen preconditioning against ischemic stroke

Ischemic stroke (IS) has become the second leading cause of morbidity and mortality worldwide, and the prevention of IS should be given high priority. Recent studies have indicated that hyperbaric oxygen preconditioning (HBO-PC) may be a protective nonpharmacological method, but its underlying mechanisms remain poorly defined. This study comprehensively reviewed the pathophysiology of IS and revealed the underlying mechanism of HBO-PC in protection against IS. The preventive effects of HBO-PC against IS may include inducing antioxidant, anti-inflammation, and anti-apoptosis capacity; activating autophagy and immune responses; upregulating heat shock proteins, hypoxia-inducible factor-1, and erythropoietin; and exerting protective effects upon the blood-brain barrier. In addition, HBO-PC may be considered a safe and effective method to prevent IS in combination with stem cell therapy. Although the benefits of HBO-PC on IS have been widely observed in recent research, the implementation of this technique is still controversial due to regimen differences. Transferring the results to clinical application needs to be taken carefully, and screening for the optimal regimen would be a daunting task. In addition, whether we should prescribe an individualized preconditioning regimen to each stroke patient needs further exploration.

Use of hyperbaric oxygen therapy for preventing delayed neurological sequelae in patients with carbon monoxide poisoning: A multicenter, prospective, observational study in Japan

BACKGROUND

The purpose of this study was to clarify the practical clinical treatment for acute carbon monoxide (CO) poisoning in Japan and to investigate the efficacy of hyperbaric oxygen (HBO2) therapy in preventing delayed neurological sequelae (DNS) in the acute phase of CO poisoning.

METHODS

We conducted a multicenter, prospective, observational study of acute CO poisoning in Japan. Patients with acute CO poisoning were enrolled and their treatment details were recorded. The primary endpoint was the onset of DNS within 2 months of CO exposure. Factors associated with DNS were assessed with logistic regression analysis.

RESULTS

A total of 311 patients from 57 institutions were registered and 255 were analyzed: 171 received HBO2 therapy (HBO2 group) and 84 did not (normobaric oxygen [NBO2] group). HBO2 therapy was performed zero, once, twice, or three times within the first 24 h in 1.8%, 55.9%, 30.9%, and 11.3% of the HBO2 group, respectively. The treatment pressure in the first HBO2 session was 2.8 ATA (47.9% of the HBO2 group), 2.0 ATA (41.8%), 2.5 ATA (7.9%), or another pressure (2.4%). The incidence of DNS was 13/171 (7.6%) in the HBO2 group and 3/84 (3.6%) in the NBO2 group (P = 0.212). The number of HBO2 sessions in the first 24 h was one of the factors associated with the incidence of DNS (odds ratio, 2.082; 95% confidence interval, 1.101-3.937; P = 0.024).

CONCLUSIONS

The practical clinical treatment for acute CO poisoning, including HBO2 therapy, varied among the institutions participating in Japan. HBO2 therapy with inconsistent protocols showed no advantage over NBO2 therapy in preventing DNS. Multiple HBO2 sessions was associated with the incidence of DNS.

Repeated exposure to hyperbaric hyperoxia affects mitochondrial functions of the lung fibroblasts

Hyperbaric oxygen (HBO) therapy, i.e. breathing pure oxygen under increased environmental pressures serves as a treatment for diverse medical conditions. However, elevated oxygen concentration can be detrimental to central nervous system or lungs. Our study aimed to evaluate the effects of repeated exposure to HBO on mitochondrial respiration assessed by high-resolution respirometry (HRR), cell viability estimated by PrestoBlue® reaction, morphology analyzed by routine phase contrast and fluorescent microscopy, and superoxide dismutase (SOD) and citrate synthase (CS) activities using human lung fibroblasts. The cells were exposed to HBO for 2 h per day for 5 consecutive days. One day after the last exposure, HBO cells displayed significantly smaller area and perimeter, compromised viability and elevated SOD activity. No changes were detected in CS activity or quality of mitochondrial network. HRR revealed impaired mitochondrial oxygen consumption manifested by increased leak respiration, decreased activity of complex II and compromised ATP-related oxygen consumption when fatty acids were oxidized. Our findings document that in conditions mimicking chronic intermittent exposure to HBO, lung fibroblasts suffer from compromised mitochondrial respiration linked to complex II and impaired cellular growth in spite of increased antioxidant defense. Underlying mechanism of this HBO-induced mitochondrial dysfunction should be further explored.

Hyperbaric oxygen and aerobic exercise in the long-term treatment of fibromyalgia: A narrative review

Chronic pain is one of the most common clinical presentations in the primary care settings. In the US, Fibromyalgia (FM) affects about 1-3% of adults and commonly occurs in adults between the ages of 40-50 years. FM causes widespread muscular pain and tenderness with hyperalgesia and allodynia and may be associated with other somatic complaints. Hyperbaric oxygen therapy (HBOT) has been utilized and has recently shown promising effects in the management of FM and other chronic pain disorders. In HBOT, the intermittent breathing of 100% oxygen in a pressurized chamber where the pressure is higher than 1 atmosphere absolute (ATA) has been utilized. HBOT exhibits a significant anti-inflammatory effect through reducing production of glial cells and inflammatory mediators which results in pain alleviation in different chronic pain conditions. HBOT can also influence neuroplasticity and affects the mitochondrial mechanisms resulting in functional brain changes. In addition to that, HBOT stimulates nitric oxide (NO) synthesis which helps in alleviating hyperalgesia and NO-dependent release of endogenous opioids which seemed to be the primary HBOT mechanism of antinociception. Moreover, aerobic exercise and meditative movement therapies (MMT) have gained attention for their role in pain alleviation through different anti-inflammatory and antioxidant mechanisms. In this review, we aim to elucidate the different mechanisms of HBOT and aerobic exercise in attenuating pain as adjuvant therapy in the multidisciplinary treatment strategy of chronic pain, and more particularly fibromyalgia.

The cerebral circulation and cerebrovascular disease III: Stroke

In this paper, our review series on cerebrovascular disease anatomy, physiology, and pathology ends with a thorough discussion of the most significant cerebrovascular pathology: stroke. This discussion proceeds through two layers of organization. First, stroke is divided up into its main etiologic categories (ischemic stroke/transient ischemic attack, hemorrhagic stroke, and ischemic to hemorrhagic transformation). Then, the epidemiological, pathophysiological, clinical, and therapeutic (employed currently as well as emerging) aspects of each etiology are explored; emphasis is placed upon the therapeutic aspects. Finally, once we have covered all aspects of each etiologic category, we end our review with a defense of the thesis that there is much hope for the future of stroke treatment to be derived from familiarity with the literature on emerging therapies.

Hyperbaric oxygen preconditioning: a reliable option for neuroprotection

Brain injury is the leading cause of death and disability worldwide and clinically there is no effective therapy for neuroprotection. Hyperbaric oxygen preconditioning (HBO-PC) has been experimentally demonstrated to be neuroprotective in several models and has shown efficiency in patients undergoing on-pump coronary artery bypass graft (CABG) surgery. Compared with other preconditioning stimuli, HBO is benign and has clinically translational potential. In this review, we will summarize the results in experimental brain injury and clinical studies, elaborate the mechanisms of HBO-PC, and discuss regimes and opinions for future interventions in acute brain injury.

The Efficacy of Hyperbaric Oxygen Therapy on Middle Cerebral Artery Occlusion in Animal Studies: A Meta-Analysis

Background

Inconsistent results have been reported for hyperbaric oxygen therapy (HBO) for acute stroke. We conducted a systematic review and meta-analysis to evaluate the benefit of HBO in animal studies of middle cerebral artery occlusion (MCAO).

Methods

A systematic search of the literature published prior to September 2015 was performed using Embase, Medline (OvidSP), Web of Science and PubMed. Keywords included “hyperoxia” OR “hyperbaric oxygen” OR “HBO” AND “isch(a)emia” OR “focal cerebral ischemia” OR “stroke” OR “infarct” OR “middle cerebral artery occlusion (MCAO).” The primary endpoints were the infarct size and/or neurological outcome score evaluated after HBO treatment in MCAO. Heterogeneity was analyzed using Cochrane Library’s RevMan 5.3.5.

Results

Fifty-one studies that met the inclusion criteria were identified among the 1198 studies examined. When compared with control group data, HBO therapy resulted in infarct size reduction or improved neurological function (32% decrease in infarct size; 95% confidence interval (CI), range 28%–37%; p < 0.00001). Mortality was 18.4% in the HBO group and 26.7% in the control group (RR 0.72, 95% CI, 0.54–0.98; p = 0.03). Subgroup analysis showed that a maximal neuro-protective effect was reached when HBO was administered immediately after MCAO with an absolute atmospheric pressure (ATA) of 2.0 (50% decrease; 95% CI, 43% -57% decrease; p < 0.0001) and more than 6 hours HBO treatment (53% decrease; 95% CI, 41% -64% decrease; p = 0.0005).

Conclusions

HBO had a neuro-protective effect and improved survival in animal models of MCAO, especially in animals given more than 6 hours of HBO and when given immediately after MCAO with 2.0 ATA.

Neuroprotective effect of gui zhi (ramulus cinnamomi) on ma huang- (herb ephedra-) induced toxicity in rats treated with a ma huang-gui zhi herb pair

Herb Ephedra (Ma Huang in Chinese) and Ramulus Cinnamomi (Gui Zhi in Chinese) are traditional Chinese herbs, often used together to treat asthma, nose and lung congestion, and fever with anhidrosis. Due to the adverse effects of ephedrine, clinical use of Ma Huang is restricted. However, Gui Zhi extract has been reported to decrease spontaneous activity in rats and exert anti-inflammatory and neuroprotective effects. The present study explored the possible inhibitory effect of Gui Zhi on Ma Huang-induced neurotoxicity in rats when the two herbs were used in combination. All Ma Huang and Ma Huang-Gui Zhi herb pair extracts were prepared using methods of traditional Chinese medicine and were normalized based on the ephedrine content. Two-month-old male Sprague-Dawley rats (n = 6 rats/group) were administered Ma Huang or the Ma Huang-Gui Zhi herb pair extracts for 7 days (ephedrine = 48 mg/kg), and locomotor activity was measured. After 7 days, oxidative damage in the prefrontal cortex was measured. Gui Zhi decreased hyperactivity and sensitization produced by repeated Ma Huang administration and attenuated oxidative stress induced by Ma Huang. The results of this study demonstrate the neuroprotective potential of Gui Zhi in Ma Huang-induced hyperactivity and oxidative damage in the prefrontal cortex of rats when used in combination.

Effects of blue light phototherapy on DNA integrity in preterm newborns

In previous studies, exposure to phototherapy, but not oxygen therapy, resulted in damage to genetic material in newborns. The objective of this study was to determine whether micronucleated erythrocytes (MNE) increased in preterm newborns (PNBs) who were exposed to blue light phototherapy lamps. MNE of mature organisms are rapidly eliminated by the spleen, and the presence of MNE has been related to immaturity in some species. Furthermore, PNBs present spontaneous MNE. Blood samples were taken from 17 PNBs at birth to establish baseline frequencies (0 h). After beginning blue light phototherapy, blood samples were obtained from 11 of these PNBs at 24-h intervals for 96 h, after the baseline sample. MNE and micronucleated polychromatic erythrocytes (MNPCE) were counted. The basal values of MNE and MNPCE from 17 PNBs were 0.62 ± 0.48 and 1.52 ± 1.28 (‰), respectively, and no increase in MNE or MNPCE was observed in the serial samples of 11 PNBs exposed to blue light and oxygen therapies, though previous studies reported increases using other types of lamps. In conclusion, under the conditions described no increase in the number of MNE or MNPCE was observed in the peripheral blood of PNBs exposed to blue light phototherapy.

Hyperbaric oxygen therapy in acute ischemic stroke: a review

Stroke, also known as cerebrovascular disease, is a common and serious neurological disease, which is also the fourth leading cause of death in the United States so far. Hyperbaric medicine, as an emerging interdisciplinary subject, has been applied in the treatment of cerebral vascular diseases since the 1960s. Now it is widely used to treat a variety of clinical disorders, especially hypoxia-induced disorders. However, owing to the complex mechanisms of hyperbaric oxygen (HBO) treatment, the therapeutic time window and the undefined dose as well as some common clinical side effects (such as middle ear barotrauma), the widespread promotion and application of HBO was hindered, slowing down the hyperbaric medicine development. In August 2013, the US Food and Drug Administration declared artery occlusion as one of the 13 specific indications for HBO therapy. This provides opportunities, to some extent, for the further development of hyperbaric medicine. Currently, the mechanisms of HBO therapy for ischemic stroke are still not very clear. This review focuses on the potential mechanisms of HBO therapy in acute ischemic stroke as well as the time window.

A comparison of factors involved in the development of central nervous system and pulmonary oxygen toxicity in the rat

Central nervous system oxygen toxicity (CNS-OT) can occur in humans at pressures above 2atmospheres absolute (ATA), and above 4.5ATA in the rat. Pulmonary oxygen toxicity appears at pressures above 0.5ATA. We hypothesized that exposure to mild HBO following extreme exposure might provide protection against CNS, but not pulmonary oxygen toxicity. We measured the activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX), and nitrotyrosine and nNOS levels in the brain and lung in the following groups: (1) Sham rats, no pressure exposure (SHAM); (2) Exposure to 6ATA oxygen for 60% of latency to CNS-OT (60%LT); (3) Exposure to 6ATA for 60% of latency to CNS-OT, followed by 20min at 2.5ATA for recovery (REC); (4) Exposure to 6ATA for 60% of latency to CNS-OT, followed by 20min at 2.5ATA oxygen and a subsequent increase in pressure to 6ATA until the appearance of convulsions (CONV); (5) Control rats exposed to 6ATA until the appearance of convulsions (C). SOD and CAT activity were reduced in both brain and lung in the REC group. GPX activity was reduced in the hippocampus in the REC group, but not in the cortex or the lung. nNOS levels were reduced in the hippocampus in the REC group. Contrary to our hypothesis, no difference was observed between the brain and the lung for the factors investigated. We suggest that at 2.5ATA and above, CNS and pulmonary oxygen toxicity may share similar mechanisms.

Perfluorocarbon-facilitated CNS oxygen toxicity in rats: reversal by edaravone

Perfluorocarbon (PFC) has been hypothesized to potentially increase the risk of central nervous system oxygen toxicity (CNS-OT) under hyperbaric oxygen (HBO) conditions. However, little is known about the effects, mechanism and prevention of PFC-facilitated CNS-OT. A rat model of CNS-OT was used to evaluate the effects of intravenously-administered PFC emulsion. The electroencephalogram (EEG) was recorded during treatment with HBO(2) at 6.0 ATA in the presence and absence of PFC. Concentrations of malondialdehyde (MDA), nitric oxide (NO) and hydrogen peroxide (H(2)O(2)) in the brain cortex and hippocampus were quantified. Changes in the activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT) and NO synthase (NOS) in the brain cortex and hippocampus were also determined. Edaravone, a potent antioxidant, was used to prevent PFC-facilitated CNS-OT. The results showed that after PFC administration, the latency to first electrical discharge in EEG was significantly shortened; MDA, H(2)O(2), NO levels and NOS activity increased; and SOD, GPx and CAT activities decreased. Edaravone effectively protected against CNS-OT and the adverse effects of PFC. The results clearly demonstrate that PFC administered before HBO(2) would promote the occurrence of CNS-OT, and edaravone could serve as a promising chemoprophylactic agent to prevent CNS-OT.

Nitric oxide-mediated central sympathetic excitation promotes CNS and pulmonary O₂ toxicity

In hyperbaric oxygen (HBO(2)) at or above 3 atmospheres absolute (ATA), autonomic pathways link central nervous system (CNS) oxygen toxicity to pulmonary damage, possibly through a paradoxical and poorly characterized relationship between central nitric oxide production and sympathetic outflow. To investigate this possibility, we assessed sympathetic discharges, catecholamine release, cardiopulmonary hemodynamics, and lung damage in rats exposed to oxygen at 5 or 6 ATA. Before HBO(2) exposure, either a selective inhibitor of neuronal nitric oxide synthase (NOS) or a nonselective NOS inhibitor was injected directly into the cerebral ventricles to minimize effects on the lung, heart, and peripheral circulation. Experiments were performed on both anesthetized and conscious rats to differentiate responses to HBO(2) from the effects of anesthesia. EEG spikes, markers of CNS toxicity in anesthetized animals, were approximately four times as likely to develop in control rats than in animals with central NOS inhibition. In inhibitor-treated animals, autonomic discharges, cardiovascular pressures, catecholamine release, and cerebral blood flow all remained below baseline throughout exposure to HBO(2). In control animals, however, initial declines in these parameters were followed by significant increases above their baselines. In awake animals, central NOS inhibition significantly decreased the incidence of clonic-tonic convulsions or delayed their onset, compared with controls. The novel findings of this study are that NO produced by nNOS in the periventricular regions of the brain plays a critical role in the events leading to both CNS toxicity in HBO(2) and to the associated sympathetic hyperactivation involved in pulmonary injury.

Evaluation of the oxidative effect of long-term repetitive hyperbaric oxygen exposures on different brain regions of rats

Hyperbaric oxygen (HBO₂) exposure affects both oxidative and antioxidant systems. This effect is positively correlated with the exposure time and duration of the treatment. The present study aims enlightening the relation of HBO₂ with oxidative/antioxidant systems when administered in a prolonged and repetitive manner in brain tissues of rats. Sixty rats were divided into 6 study (n = 8 for each) and 1 control (n = 12) group. Rats in the study groups were daily exposed 90-min HBO₂ sessions at 2.8 ATA for 5, 10, 15, 20, 30 and 40 days. One day after the last session, animals were sacrificed; their whole brain tissue was harvested and dissected into three different regions as the outer grey matter (cortex), the inner white matter and cerebellum. Levels of lipid peroxidation and protein oxidation and activities of superoxide dismutase and glutathione peroxidase were measured in these tissues. Malondialdehyde, carbonylated protein and glutathione peroxidase levels were found to be insignificantly increased at different time-points in the cerebral cortex, inner white matter and cerebellum, respectively. These comparable results provide evidence for the safety of HBO treatments and/or successful adaptive mechanisms at least in the brain tissue of rats, even when administered for longer periods.

Similarities and differences of hyperbaric oxygen and medical ozone applications

Hyperbaric oxygen (HBO) treatment is based on the principle of having the patient breath 100% oxygen in an environment above atmospheric pressure. Ozone (O(3)) is a colourless gas with a specific odour and consists of three oxygen atoms. The classical scientific understanding is that the world has become a place suitable for life for aerobic organisms with the increasing oxygen in the atmosphere billions of years ago. The formation of ozone after oxygen has then protected aerobic creatures from harmful rays. We now use these two gases for treatment purposes. It is noteworthy that the oxygen and ozone molecules that are formed by the same atom in different numbers are used for similar medical indications. We will try to emphasize the similarities and differences of HBO and medical ozone applications in this article.

The neuroprotective effect of curcumin and Nigella sativa oil against oxidative stress in the pilocarpine model of epilepsy: a comparison with valproate

Oxidative stress has been implicated to play a role in epileptogenesis and pilocarpine-induced seizures. The present study aims to evaluate the antioxidant effects of curcumin, Nigella sativa oil (NSO) and valproate on the levels of malondialdehyde, nitric oxide, reduced glutathione and the activities of catalase, Na⁺, K⁺-ATPase and acetylcholinesterase in the hippocampus of pilocarpine-treated rats. The animal model of epilepsy was induced by pilocarpine and left for 22 days to establish the chronic phase of epilepsy. These animals were then treated with curcumin, NSO or valproate for 21 days. The data revealed evidence of oxidative stress in the hippocampus of pilocarpinized rats as indicated by the increased nitric oxide levels and the decreased glutathione levels and catalase activity. Moreover, a decrease in Na⁺, K⁺-ATPase activity and an increase in acetylcholinesterase activity occurred in the hippocampus after pilocarpine. Treatment with curcumin, NSO or valproate ameliorated most of the changes induced by pilocarpine and restored Na⁺, K⁺-ATPase activity in the hippocampus to control levels. This study reflects the promising anticonvulsant and potent antioxidant effects of curcumin and NSO in reducing oxidative stress, excitability and the induction of seizures in epileptic animals and improving some of the adverse effects of antiepileptic drugs.

Survival and differentiation of neuroectodermal cells with stem cell properties at different oxygen levels

Freeze-lesioned regions of the forebrain cortex provide adequate environment for growth of non-differentiated neural progenitors, but do not support their neuron formation. Reduced oxygen supply, among numerous factors, was suspected to impair neuronal cell fate commitment. In the present study, proliferation and differentiation of neural stem/progenitor cells were investigated at different oxygen levels both in vitro and in vivo. Low (1% atmospheric) oxygen supply did not affect the in vitro viability and proliferation of stem cells or the transcription of "stemness" genes but impaired the viability of committed neuronal progenitors and the expression of proneural and neuronal genes. Consequently, the rate of in vitro neuron formation was markedly reduced under hypoxic conditions. In vivo, neural stem/progenitor cells survived and proliferated in freeze-lesioned adult mouse forebrains, but did not develop into neurons. Hypoperfusion-caused hypoxia in lesioned cortices was partially corrected by hyperbaric oxygen treatment (HBOT). HBOT, while reduced the rate of cell proliferation at the lesion site, resulted in sporadic neuron formation from implanted neural stem cells. The data indicate that in hypoxic brain areas, neural stem cells survive and proliferate, but neural tissue-type differentiation can not proceed. Oxygenation renders the damaged brain areas more permissive for tissue-type differentiation and may help the integration of neural stem/progenitor cells.

Effect of preconditioned hyperbaric oxygen and ozone on ischemia-reperfusion induced tourniquet in skeletal bone of rats

BACKGROUND

The aim of the study was to investigate effect of I/R injury on bone tissue and protective role of hyperbaric oxygen precondition (HBO-PC) and ozone precondition (O(3)-PC) on I/R injury by using biochemical analysis.

MATERIALS AND METHODS

Thirty-two rats were included in study. The animals were divided into four equal groups: sham operation, I/R, I/R+HBO and I/R+O(3). One session of 60 min, 3 ATA, 3-4 L/min, 100% oxygenation was defined as one dose of HBO. First dose of HBO was administrated 72 h before ischemia. Subsequent, one-dose of HBO administrated per 12 hours until ischemia time (total seven doses); 0.7 mg/kg ozone/oxygen mixture intraperitoneally was defined as one dose of ozone. First dose of O(3) was administered 72 h before ischemia (total four doses). I/R model was induced in anesthetized rats by unilateral (right) femoral artery clipping for 2 h followed by 22 h of reperfusion. The right tibia and were harvested. Tissue was assayed for levels of malondialdehyde (MDA) and protein carbonyl (PCO), activities of superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px).

RESULTS

MDA and PCO levels were increased in I/R group. SOD activity was increased; GSH-Px activity was decreased in I/R group. MDA and PCO levels were decreased, SOD and GSH-Px activities were increased in both HBO+I/R and O(3)+I/R groups.

CONCLUSION

It has been shown that levels of MDA and PCO in bone were increased followed by 2 h of ischemia and 22 h of reperfusion period. Ozone-PC and HBO-PC has protective effect against skeletal bone I/R injury by decreasing levels of MDA and PCO, increasing activities of SOD and GSH-Px in rats.

Hyperbaric oxygen therapy reduces the severity of necrotizing enterocolitis in a neonatal rat model

INTRODUCTION

Hyperbaric oxygen (HBO) therapy is known to increase oxygen concentration in tissues leading to induction of an adaptive increase in antioxidants, stimulation of angiogenesis, improvement of white blood cell action, and regulation of inflammatory process. Therefore, we tested the potential beneficial effect of HBO in neonatal rat model of necrotizing enterocolitis (NEC).

MATERIALS AND METHODS

Thirty newborn Sprague-Dawley rats, provided by the Experimental Research Council, Gulhane Military Medical Academy, Ankara,Turkey, were randomly divided into 3 groups as follows: NEC, NEC + HBO, and control. Necrotizing enterocolitis was induced by enteral formula feeding and exposure to hypoxia after cold stress at 4 degrees C and oxygen. The NEC + HBO group received HBO at 2.8 atmosphere absolute (ATA) for 90 minutes daily for 3 days. The pups were killed on the fourth day, and their intestinal tissues were harvested for biochemical and histopathologic analysis. Blood samples were also obtained from the pups.

RESULTS

The mortality rate was highest in the NEC group (3 pups in the NEC group vs 1 pup in the NEC + HBO group). Malondialdehyde and protein carbonyl content were significantly increased, whereas superoxide dismutase and glutathione peroxidase were significantly decreased in the NEC group. All these changes were similar to control levels in the NEC group by HBO treatment. Nitrate plus nitrite (NO(x)) levels and serum tumor necrosis factor alpha were increased in the NEC group and histopathologic injury score and apoptosis index in the NEC group were significantly higher than in the NEC + HBO group.

CONCLUSION

Hyperbaric oxygen significantly reduced the severity of NEC in our study.

Effect of hyperbaric oxygen treatment on oxidative stress in patients having diabetes mellitus type 2

Introduction The aim of our study was to investigate the influence of breathing oxygen under high pressure on potential prooxidative activity in diabetic patients with serious vascular complications. Material and methods 24 patients with diabetes mellitus type 2, were divided into two groups, 12 patients each, by degree of peripheral vascular complications (by Wagner's scale). The group I was composed of 4 women and 8 men, their average age being 70 years, and average Diabetes duration of 12 years, without clinically manifest peripheral vascular complication (Wagner 0). The group II was composed of 4 women and 8 men, their average age being 74 years, and average illness duration of 17 years, having peripheral vascular complications, classified by Wagner's scale 1-5. Blood samples for biochemical analysis were taken before the therapy, then on the 3rd, 5th, 7th and 10th day of hyperbaric oxygenation treatment. The values of superoxide anion radical (O-), hydrogen peroxide (H2O2) and TBARS as a parameter of lipid peroxidation were measured during the HBOt. All examined patients were treated with the same therapy protocol (10 HBO treatments, under pressure of 1.7-2.2 bar, in duration of 60 minutes). The therapy was provided in monoplace oxygen hyperbaric chamber. Results The obtained results show no statistically significant increase in the values of O2-, H2O2, TBARS during the HBOt compared to the values before the HBOt. However, O2-, H2O2 were significantly reduced after HBOt. Conclusion On the basis of these data, we can conclude that the use of oxygen under high pressure has no influence on the increased prooxidative activities in diabetic patients during and after HBOt, disregarding the degree of the present vascular damages.