A new utilization area for hyperbaric oxygen? Improving quality of stored blood.

BACKGROUND/AIM: Since blood bags have the ability for diffusion of gases, we investigated whether hyperbaric oxygen (HBO) exposure affects several vital parameters of stored blood. MATERIALS AND METHODS: Bloods obtained from the same persons were used as both control and HBO groups and stored in pediatric bags with citrate-phosphate-dextrose solution. HBO administration was performed at 2.5 atm for 90 min, started 1 day after blood collection and repeated every 2 days for a total of 10 times. The study was terminated on the 21st day. Complete blood count, glucose, pH, and osmotic fragility values were measured every week. RESULTS: Glucose and pH levels decreased in stored blood. In the HBO-exposed group, these decreases were less than in the control. In addition, mean corpuscular and platelet volumes tended to increase during storing process, but with HBO, these indexes remained lower, near physiologic levels. Another interesting finding of the study was the relative stable osmotic fragility ratio in the HBO group compared to the control blood. CONCLUSION: HBO exposure has positive effects on pH, stability of erythrocytes, and energy source (glucose) of the medium. Thus, we concluded that HBO may be a useful application for life and quality of stored blood.

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

Hyperbaric oxygen (HBO(2)) 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 HBO(2) 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 HBO(2) 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.

The protective effects of ozone therapy in a rat model of acetaminophen-induced liver injury.

OBJECTIVES: Acetaminophen (APAP) overdose may cause acute liver injury. Ozone therapy (OT) is shown to reduce inflammation and necrosis in several entities. Thus, we have designed this study to evaluate the efficacy of OT in a rat model of APAP-induced liver injury. METHODS: Twenty-seven Sprague-Dawley rats were divided into three groups: sham, APAP and APAP+OT groups. In the APAP and the APAP+OT groups, liver injury was induced by oral administration of 1 g/kg APAP. The APAP+OT group received a single dose ozone/oxygen mixture (0.7 mg/kg) intraperitoneally 1h after APAP administration. All animals were killed at 24 hour after APAP administration. Blood samples and liver tissues were harvested to determine liver injury and oxidative stress parameters. Liver tissues and blood samples were obtained for biochemical and histopathological analyses. RESULTS: APAP administration caused necrosis in the liver after 24h. The degrees of liver necrosis of the APAP group were higher than the other groups (in both p<0.05, respectively). In the APAP+OT group, liver antioxidant enzymes activities were significantly higher than the APAP group (p<0.05), but were lower than the sham group (p<0.05). In the sham group, serum neopterin, a marker of cell-mediated immunity, concentrations (4.8±1.2 nmol/L) were lower than the APAP (14.7±1.4 nmol/L) and APAP+OT groups (7.5±2.4 nmol/L) (in both p<0.05, respectively). CONCLUSION: Our results showed that OT prevented liver necrosis in rats and reduced neopterin levels. These findings suggest that the use of OT as an adjuvant therapy which might improve the outcome in APAP induced liver injury.

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.

Inhibition of iNOS reduces the therapeutic effects of ozone in acute necrotizing pancreatitis: an in vivo animal study.

OBJECTIVE: Previously, it was shown that ozone and S-methylthiourea (SMT) treatments had ameliorative effects on experimental models of acute necrotizing pancreatitis (ANP). It is possible that the combination of ozone and SMT may be more effective than either therapy. Therefore, we investigated the efficacy of combination therapy with ozone and SMT in an experimental rat model of ANP. MATERIAL AND METHODS: Sprague-Dawley rats were divided into five experimental groups. Groups were designed as Sham-operated, ANP, ANP + Ozone, ANP + SMT and ANP + Ozone + SMT. A model of ANP was induced by injection of sodium taurocholate into the common biliopancreatic duct. Four days after induction, blood and tissue samples were obtained for biochemical, microbiological and histopathological analysis. RESULTS: Survival rates, serum amylase, lipase and neopterin levels, tissue oxidative stress parameters, bacterial translocation and tissue injury scores were better in the ozone and SMT groups than in the ANP group. There was no bacterial translocation in the ozone-treated groups. Tissue injury scores in the ozone group were better compared to all ANP induced groups. Ozone and SMT treatment in combination did not have better biochemical, microbiological and histological data compared to ozone or SMT treatments separately in experimental ANP. CONCLUSIONS: The combination of ozone and SMT did not provide any therapeutic advantage in ANP possibly because SMT inhibited nitric oxide synthesis which was needed for ozone action.

Long-term exposure to repetitive hyperbaric oxygen results in cumulative oxidative stress in rat lung tissue.

CONTEXT: Despite its known benefits, hyperbaric oxygen (HBO) is also reported to enhance the production of reactive oxygen species and can cause oxidative stress in several tissues. Previous studies had shown that HBO-induced oxidative stress is directly proportional to both its exposure pressure and duration. Nevertheless, these studies were usually performed with single-session HBO exposure but its clinical use commonly depends on long-term exposure periods. OBJECTIVE: To clarify the oxidative effect of long-term repetitive HBO in the lung tissue of rats. MATERIALS AND METHODS: Male Sprague-Dawley rats were divided into six study groups exposed to consecutive HBO sessions (2.8 atm/90 min) for 5, 10, 15, 20, 30, and 40 days. Animals were sacrificed 24 h after the last HBO session. An additional control group was set to obtain normal data. Lung malondialdehyde (MDA) and carbonylated protein (PCC) levels were determined as measures of oxidative stress along with the activities of the antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase. RESULTS: None of the measured parameters showed any changes among the groups exposed to 5-15 HBO sessions. However, MDA, PCC, and SOD were found to be significantly increased in the 20 to 40 session groups. DISCUSSION AND CONCLUSION: These results indicate that repetitive treatment with HBO may cause oxidative stress in critical tissues including the lung. Although HBO-mediated free radicals are accepted to be responsible for the benefits of this therapeutic modality, especially in cases with prolonged exposure, possible injurious effects of supranormal values of bio-oxidative products need to be considered.

Ozone therapy and hyperbaric oxygen treatment in lung injury in septic rats.

Various therapeutic protocols were used for the management of sepsis including hyperbaric oxygen (HBO) therapy. It has been shown that ozone therapy (OT) reduced inflammation in several entities and exhibits some similarity with HBO in regard to mechanisms of action. We designed a study to evaluate the efficacy of OT in an experimental rat model of sepsis to compare with HBO. Male Wistar rats were divided into sham, sepsis+cefepime, sepsis+cefepime+HBO, and sepsis+cefepime+OT groups. Sepsis was induced by an intraperitoneal injection of Escherichia coli; HBO was administered twice daily; OT was set as intraperitoneal injections once a day. The treatments were continued for 5 days after the induction of sepsis. At the end of experiment, the lung tissues and blood samples were harvested for biochemical and histological analysis. Myeloperoxidase activities and oxidative stress parameters, and serum proinflammatory cytokine levels, IL-1ß and TNF-α, were found to be ameliorated by the adjuvant use of HBO and OT in the lung tissue when compared with the antibiotherapy only group. Histologic evaluation of the lung tissue samples confirmed the biochemical outcome. Our data presented that both HBO and OT reduced inflammation and injury in the septic rats' lungs; a greater benefit was obtained for OT. The current study demonstrated that the administration of OT as well as HBO as adjuvant therapy may support antibiotherapy in protecting the lung against septic injury. HBO and OT reduced tissue oxidative stress, regulated the systemic inflammatory response, and abated cellular infiltration to the lung demonstrated by findings of MPO activity and histopathologic examination. These findings indicated that OT tended to be more effective than HBO, in particular regarding serum IL-1ß, lung GSH-Px and histologic outcome.

Comparison of hyperbaric oxygen and medical ozone therapies in a rat model of experimental distal colitis.

OBJECTIVES: Previous studies have shown that hyperbaric oxygen (HBO) is effective in reducing the severity of acute distal colitis (ADC). Ozone therapy (OT) reduces inflammation in several pathological conditions. We aimed to compare the effects of HBO therapy and OT in an experimental ADC rat model. MATERIALS AND METHODS: Forty rats were randomly divided into four groups: Sham, ADC, ADC + HBO, and ADC + OT. Rats in the sham group were given isotonic saline. In the remaining groups, ADC was created by intracolonic administration of 4% acetic acid. No treatment was given to the ADC group. The rats in the ADC + HBO and ADC + OT groups were given HBO and ozone treatments, respectively. The administration of acetic acid caused an inflammatory response in all animals. Distal colons and blood samples were obtained. RESULTS: The histopathological score was significantly higher in the ADC group compared to the other groups. The histopathological scores in the ADC + HBO and ADC + OT groups were significantly lower compared to the ADC group (both p < 0.001). The most pronounced therapeutic effect was observed in the ADC + OT group. Malondialdehyde and neopterin levels and superoxide dismutase and glutathione peroxidase activities in the ADC group were significantly higher compared to the other groups (p < 0.001). CONCLUSION: Our data showed that the therapeutic effect of OT is more pronounced than that of HBO therapy. Its possible effect is by means of decreasing inflammation, edema, and oxidative stress. These findings also suggest that it is possible to improve the outcome of ADC by using ozone therapy as an adjuvant therapy.

Efficacy of hyperbaric oxygen therapy and medical ozone therapy in experimental acute necrotizing pancreatitis.

OBJECTIVES: Our aims were to evaluate the efficacy of ozone therapy (OT) in an experimental rat model of acute necrotizing pancreatitis (ANP) and to compare its effects with hyperbaric oxygen (HBO) therapy in this entity. METHODS: Forty Sprague-Dawley rats were divided into sham-operated, ANP, ANP + HBO, and ANP + OT groups. Acute necrotizing pancreatitis was induced by infusing 1-mL/kg 3% sodium taurocholate into the common biliopancreatic duct. Hyperbaric oxygen was administered twice daily at a 2.8-atm pressure for 90 minutes. Ozone therapy was set as daily intraperitoneal injections of 0.7-mg/kg ozone/oxygen gas mixture. Hyperbaric oxygen and OT were continued for 3 days after the induction of ANP. The surviving animals were killed at the fourth day, and their pancreases were harvested for biochemical, microbiological, and histopathologic analyses. RESULTS: Serum amylase/lipase and neopterin levels and tissue oxidative stress parameters were similar to sham's values in both the ANP + HBO and the ANP + OT groups. Histopathologic injury scores were significantly lower in the treatments groups than in the ANP group. When compared with the ANP group, the number of infected rats was significantly lesser in the ANP + HBO and the ANP + OT groups. CONCLUSIONS: Hyperbaric oxygen and OT reduce the severity and the mortality in the experimental rat model of ANP, and a greater benefit was received for OT comparing with HBO.

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.

DNA damage after long-term repetitive hyperbaric oxygen exposure.

A single exposure to hyperbaric oxygen (HBO), i.e., pure oxygen breathing at supra-atmospheric pressures, causes oxidative DNA damage in humans in vivo as well as in isolated lymphocytes of human volunteers. These DNA lesions, however, are rapidly repaired, and an adaptive protection is triggered against further oxidative stress caused by HBO exposure. Therefore, we tested the hypothesis that long-term repetitive exposure to HBO would modify the degree of DNA damage. Combat swimmers and underwater demolition team divers were investigated because their diving practice comprises repetitive long-term exposure to HBO over years. Nondiving volunteers with and without endurance training served as controls. In addition to the measurement of DNA damage in peripheral blood (comet assay), blood antioxidant enzyme activities, and the ratio of oxidized and reduced glutathione content, we assessed the DNA damage and superoxide anion radical (O(2)(*-)) production induced by a single ex vivo HBO exposure of isolated lymphocytes. All parameters of oxidative stress and antioxidative capacity in vivo were comparable in the four different groups. Exposure to HBO increased both the level of DNA damage and O(2)(*-) production in lymphocytes, and this response was significantly more pronounced in the cells obtained from the combat swimmers than in all the other groups. However, in all groups, DNA damage was completely removed within 1 h. We conclude that, at least in healthy volunteers with endurance training, long-term repetitive exposure to HBO does not modify the basal blood antioxidant capacity or the basal level of DNA strand breaks. The increased ex vivo HBO-related DNA damage in isolated lymphocytes from these subjects, however, may reflect enhanced susceptibility to oxidative DNA damage.

Establishing the use of melatonin as an adjuvant therapeutic against paraquat-induced lung toxicity in rats.

It is well known that the intake of paraquat (PQ) causes severe tissue injury leading to numerous fatalities. Considering that the main target for PQ toxicity is the lung and involves the production of reactive oxygen and nitrogen species, transcription factors and inflammatory cytokines, it may be hypothesized that the combination of a potent antiinflammatory and antioxidant agent may counteract more of PQ's effects than an antiinflammatory agent alone. For this purpose, combination of dexamethasone (Dex) and melatonin (Mel) was compared with Dex alone. A total of 40 male Wistar albino rats were divided into four groups as control, PQ, Dex only, and Dex plus Mel. The animals were given intraperitoneally a toxic dose of 19 mg/kg PQ dissolved in 1 ml saline. Control animals were injected with the same amount of saline only. A dose of 1 mg/kg Dex was administered 2 hrs after PQ administration. In the combination treatment group, 20 mg/kg Mel was given with Dex. All drugs were given every 12 hrs for a total of six doses. Five animals in PQ group and three animals in Dex only group died by the end of the study. No deaths occurred in the Dex+Mel group. Dex exerted improvements in several oxidative and antioxidative parameters. However, combination treatment provided beneficial effects against PQ toxicity far greater than Dex alone. This difference was also apparent when tissues were histologically compared. In conclusion, Mel exhibited strong additive beneficial effects with Dex and can be considered as a safe treatment modality against PQ toxicity.

Exposure time related oxidative action of hyperbaric oxygen in rat brain.

Hyperbaric oxygen (HBO) is known to cause oxidative stress in several organs and tissues. Due to its high rate of blood flow and oxygen consumption, the brain is one of the most sensitive organs to this effect. The present study was performed to elucidate the relation of HBO exposure time to its oxidative effects in rats' brain cortex tissue. For this purpose, 49 rats were randomly divided into five groups. Except the control group, study groups were subjected to three atmospheres HBO for 30, 60, 90, and 120 min. Their cerebral cortex layer was taken immediately after exposure and used for analysis. Thiobarbituric acid reactive substances (TBARS), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and nitrate-nitrite (NOX) levels were determined. TBARS and SOD levels were found to increase in a time-dependent manner. GSH-Px activity reflected an inconsistent course. NOX levels were found to be increased only in the 120 min exposed group. The results of this study suggests that HBO induced oxidative effects are strongly related with exposure time.

Oxidative stress levels in rats following exposure to oxygen at 3 atm for 0-120 min.

BACKGROUND: Hyperbaric oxygen (HBO) is known to cause oxidative stress in several organs and tissues. We previously defined the pressure-related oxidative effects of HBO in several tissues of rats. This study was performed to elucidate the relationship of HBO exposure time to its oxidative effects. METHODS: A total of 49 rats were randomly divided into 5 groups. Study groups were subjected to 3 atm HBO for 30, 60, 90, and 120 min except the control group. Their blood and lungs were removed immediately after exposure and used for analysis. Thiobarbituric acid reactive substances (TBARS), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) levels were determined to reflect oxidant and antioxidant status. RESULTS: TBARS levels were found to increase in a time-dependent manner in both erythrocytes [median (min-max); from 0.65 (0.39-0.84) with 30 min HBO exposure up to 1.26 (1.00-1.44) nmol x g(-1) hemoglobin after 120 min] and lung tissue [from 2140 (1550-2510) up to 5465 (5090-5950) nmol x g(-1) protein]. Similarly, SOD activity also presented a dose-dependent course from 0.06 (0.05-0.10) to 0.18 (0.14-0.26) U x g(-1) hemoglobin in erythrocytes and from 16,660 (3479-25,994) to 52,522.5 (41,362-65,799) U x g(-1) protein in lung tissue. In contrast, GSH-Px activity reflected an irregular trend; its levels were mostly found to be increased, but they were decreased at one stage (in the erythrocytes of 30-min exposed rats). CONCLUSIONS: The results of this study exhibited a clear relationship of HBO-induced oxidative action to exposure time. This action was most pronounced from 90 to 120 min of exposure.

Time-dependent course of hyperbaric oxygen-induced oxidative effects in rat lung and erythrocytes.

1. The oxygen toxicity of hyperbaric oxygen (HBO) treatment has long been of interest. There is an extensive amount of information regarding the role oxidative stress plays after HBO exposure in different tissues, but the question of the persistence of this oxidative effect has not been thoroughly elucidated. 2. The present study was performed to elucidate the persistence of the oxidative effects of HBO on rat lungs and erythrocytes after they had been subjected to 100% oxygen exposure. 3. Rats were divided into five groups. All animals, except those in the control group, were subjected to 100% oxygen for 2 h at 3 ATA ( identical with 300 kPa). Rats were killed at 30, 60, 90 or 120 min after exposure and thiobarbituric acid-reactive substances (TBARS) levels and the activity of superoxide dismutase (SOD) and glutathione peroxidase (GPx) were determined. 4. Thiobarbituric acid-reactive substances levels and SOD and GPx levels were found to be significantly increased in lung tissue up to 60 min after exposure. Superoxide dismutase activity persisted at significantly high values for 90 min after exposure in erythrocytes and the lung. The TBARS levels in erythrocytes were also significantly higher for 60 min, whereas increased GPx activity was observed to persist for only 30 min. 5. The oxidative effect of HBO exposure declines to physiological levels within 90 min at most for erythrocytes and in lung tissue in rats. Further studies should focus on the molecular mechanisms that can be activated during this time interval.

Pressure-related increase of asymmetric dimethylarginine caused by hyperbaric oxygen in the rat brain: a possible neuroprotective mechanism.

A decrease in nitric oxide availability in the brain tissue due to the inhibition of nitric oxide synthase (NOS) activity during the early phases of hyperbaric oxygen (HBO) exposure was found to be involved in hyperoxic vasoconstriction leading to reduced regional cerebral blood flow. We hypothesized that the concentration of asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase (NOS), may be an important factor during this hyperoxic vasoconstriction state. Rats were exposed to 1, 2 and 3 atmospheres pure oxygen for two hours. A fourth group of animals served as control. Asymmetric dimethylarginine, L-Arginine and nitrite/nitrate (NOx) concentrations were measured from deproteinized rat brain cytosols. In rat brains exposed to 3 atmospheres O2, ADMA and L-Arginine levels were found to be significantly higher and NOx significantly lower than control levels. Additionally, statistically significant correlations between ADMA and L-Arginine, and ADMA and NOx concentrations were detected. In conclusion, this is the first study indicating increased ADMA levels in rat brains exposed to HBO. The simultaneously decreased NOx values suggest that ADMA elevation resulted in NOS inhibition and therefore may be responsible for the early phase hyperoxic vasoconstriction.

Effects of methylprednisolone and hyperbaric oxygen on oxidative status after experimental spinal cord injury: a comparative study in rats.

The effects of hyperbaric oxygen (HBO) therapy or methylprednisolone on the oxidative status were evaluated in experimental spinal cord injury. Clip compression method was used to produce acute spinal cord injury rats. Hyperbaric oxygen was administered twice daily for a total of eight 90 min-sessions at 2.8 atmospheres. Methylprednisolone was first injected with a bolus of 30 mg/kg followed with an infusion rate of 5.4 mg/kg/h for 24 h. Five days after clip application animals were sacrificed and their traumatized spinal cord segment were excised. Tissue levels of thiobarbituric acid reactive substances (TBARS), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were evaluated to reflect oxidant/antioxidant status. Non-treated clip-operated animals reflected significantly higher SOD, GSH-Px and TBARS levels that were found to be significantly higher than the sham-operated. Methylprednisolone was not able to lower these levels. HBO administration diminished all measured parameters significantly; however, their levels appeared already to be high when compared with sham animals. According to these results obtained on the 5th day after induction, HBO, but not methylprednisolone, seems to procure prevention against oxidative spinal cord injury.

Persistence of hyperbaric oxygen-induced oxidative effects after exposure in rat brain cortex tissue.

Hyperbaric oxygen (HBO) causes oxidative stress in several organs and tissues. Due to its high rate of blood flow and oxygen consumption, the brain is one of the most sensitive organs to this effect. Many studies have reported oxidative effects of HBO, but there is no comprehensive data about how long this effect persists. The aim of this study was to elucidate the duration of HBO-induced oxidative/antioxidant action. Male Sprague-Dawley rats were divided into 5 groups. Except for the controls, the animals were subjected to 100% oxygen for 2 h at 3 atm and differed from each other by the time to dissection after exposure that began at 30, 60, 90, or 120 min. Thiobarbituric acid-reactive substances (TBARS), as well as superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity was determined in brain cortex tissue. Additionally, nitrite-nitrate (NO(x)) concentrations were measured. All measured parameters were found to be significantly increased 30 min after exposure. SOD and GSH-Px levels persisted at significantly high levels for 60 min. In conclusion, the oxidative effect of HBO was shown to persist only for 1 h. Further studies should be performed to elucidate the possible molecular interactions during this period.

Effects of a cantaloupe melon extract/wheat gliadin biopolymer during aortic cross-clamping.

OBJECTIVE: We previously reported in healthy volunteers that a cantaloupe melon extract chemically combined with wheat gliadin (melon extract/gliadin) and containing SOD, catalase and residual glutathione peroxidase (GPx), protected against DNA strand-break damage induced by hyperbaric oxygen (HBO), a well-established model of DNA damage resulting from oxidative stress. Aortic cross-clamping is a typical example of ischemia/reperfusion injury-related oxidative stress, and therefore we investigated whether this melon extract/gliadin would also reduce DNA damage after aortic cross-clamping and reperfusion. DESIGN: Prospective, randomized, controlled experimental study. SETTING: Animal laboratory. PATIENTS AND PARTICIPANTS: 18 anesthetized, mechanically ventilated and instrumented pigs. INTERVENTIONS: After 14 days of oral administration of 1250 mg of the melon extract/gliadin (n=9) or vehicle (n=9), animals underwent 30 min of thoracic aortic cross-clamping and 4 h of reperfusion. MEASUREMENTS AND RESULTS: Before clamping, immediately before declamping, and at 2 and 4 h of reperfusion, we measured blood isoprostane (immunoassay) and malondialdehyde concentrations (fluorimetric thiobarbituric acid test), SOD, catalase and GPx activities (spectrophotometric kits), NO formation (nitrate+nitrite; chemoluminescence), DNA damage in whole blood samples and isolated lymphocytes exposed to hyperbaric oxygen (comet assay). Organ function was also evaluated. Kidney and spinal cord specimen were analysed for apoptosis (TUNEL assay). The melon extract/gliadin blunted the DNA damage, reduced spinal cord apoptosis and attenuated NO release, however, without any effect on lipid peroxidation and organ function. CONCLUSIONS: Pre-treatment with the oral melon extract/gliadin may be a therapeutic option to reduce oxidative cell injury affiliated with aortic cross-clamping.

Antioxidant effects of melatonin in rats during chronic exposure to hyperbaric oxygen.

In addition to its beneficial effects, hyperbaric oxygen (HBO) exposure causes some detrimental effects via oxidative stress. Previous experimental studies showed that melatonin is a useful agent to block single session HBO-induced oxidative stress. In the present study, we investigated the antioxidant effect of exogenously administered as well as endogenously produced melatonin in lung and brain tissues of rats exposed to long term HBO. The HBO procedure was set as daily exposures to 2.5 ATA of oxygen for 1 hr and a total of 10 sessions. Twenty-eight male Sprague-Dawley rats were divided into four groups as follows: control, daytime HBO, daytime HBO plus melatonin (5 mg/kg), nighttime HBO. Tissue oxidative/antioxidant status was examined by determining the protein carbonyl content as a criteria for oxidative stress and the activities of the antioxidant enzymes, superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). HBO exposure for 10 days caused significant increases in protein carbonyl content and SOD levels of lung and brain, but GSH-Px activities remained unaffected. The increases in protein carbonyls were blocked by exogenously administered melatonin and in part by nighttime exposure to darkness whereas the increase of SOD activity was only impeded by endogenously produced melatonin in brain tissue. Lung SOD activity was augmented by endogenous melatonin. In conclusion, melatonin blocks long-term HBO-induced cumulative oxidative stress as indicated changes in protein carbonyls. Both exogenously injected and physiologically secreted melatonin has this potential. The effects of HBO-exposure and melatonin on the activities of the antioxidative enzymes are less clear.