Hyperbaric oxygen treatment augments the efficacy of a losartan regime in an experimental nephrotic syndrome model

Renal Effects of Hyperbaric Oxygen Therapy in Patients with Diabetes Mellitus: A Retrospective Study

Hyperbaric oxygen therapy (HBOT) is an adjunctive treatment for patients with diabetic foot ulcers. The prolonged high oxygen level used in HBOT can produce oxidative stress, which may be harmful to the kidney. Animal experiments suggest HBOT does not harm renal function and may have an antiproteinuric effect, but little is known on the effect of HBOT in humans. We performed a retrospective chart review of 94 patients with diabetes mellitus who underwent HBOT at our institution over an eight-year period. Thirty-two patients had serum creatinine levels within 60 days of the start and the end of treatment. Creatinine levels were 1.41 ± 0.89 mg/dl before and 1.52 ± 1.17 mg/dl after hyperbaric treatments with no statistically significant difference (mean (postcreatinine + precreatinine/2) = 0.10 mg/dl, SE = 0.11, t = 0.89). Twenty-three patients had proteinuria measurements before and after HBOT mainly by urine dipstick analysis. A Wilcoxon signed-rank test showed less proteinuria after HBOT than before (N = 23, p=0.002). Proteinuria was absent in 7 of 23 patients (30%) before HBOT and 13 of 23 patients (57%) after HBOT, a reduction by almost 50%. This observation is remarkable because oxidative stress might be expected to increase rather than decrease proteinuria.

Hyperbaric oxygen therapy induces kidney protection in an ischemia/reperfusion model in rats

Ischemia/reperfusion (I/R) injury remains a major cause of graft dysfunction, which impacts short- and long-term follow-up. Hyperbaric oxygen therapy (HBO), through plasma oxygen transport, has been currently used as an alternative treatment for ischemic tissues. The aim of this study was to analyze the effects of HBO on kidney I/R injury model in rats, in reducing the harmful effect of I/R. The renal I/R model was obtained by occluding bilateral renal pedicles with nontraumatic vascular clamps for 45 minutes, followed by 48 hours of reperfusion. HBO therapy was delivered an hypebaric chamber (2.5 atmospheres absolute). Animals underwent two sessions of 60 minutes each at 6 hours and 20 hours after initiation of reperfusion. Male Wistar rats (n = 38) were randomized into four groups: sham, sham operated rats; Sham+HBO, sham operated rats exposed to HBO; I/R, animals submitted to I/R; and I/R+HBO, I/R rats exposed to HBO. Blood, urine, and kidney tissue were collected for biochemical, histologic, and immunohistochemical analyses. The histopathological evaluation of the ischemic injury used a grading scale of 0 to 4. HBO attenuated renal dysfunction after ischemia characterized by a significant decrease in blood urea nitrogen (BUN), serum creatinine, and proteinuria in the I/R+HBO group compared with I/R alone. In parallel, tubular function was improved resulting in significantly lower fractional excretions of sodium and potassium. Kidney sections from the I/R plus HBO group showed significantly lower acute kidney injury scores compared with the I/R group. HBO treatment significantly diminished proliferative activity in I/R (P < .05). There was no significant difference in macrophage infiltration or hemoxygenase-1 expression. In conclusion, HBO attenuated renal dysfunction in a kidney I/R injury model with a decrease in BUN, serum creatinine, proteinuria, and fractional excretion of sodium and potassium, associated with reduced histological damage.

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.

The suffocating kidney: tubulointerstitial hypoxia in end-stage renal disease

Chronic kidney disease (CKD) is characterized by irreversible pathological processes that result in the development of end-stage renal disease (ESRD). Accumulating evidence has emphasized the important role of chronic hypoxia in the tubulointerstitium in the final common pathway that leads to development of ESRD. The causes of chronic hypoxia in the tubulointerstitium are multifactorial and include mechanisms such as hemodynamic changes and disturbed oxygen metabolism of resident kidney cells. Epidemiological studies have revealed an association between CKD and systemically hypoxic conditions, such as chronic obstructive pulmonary disease and sleep apnea syndrome. In addition to tubulointerstitial hypoxia, glomerular hypoxia can occur and is a crucial factor in the development of glomerular disorders. Chemical compounds, polarographic sensors, and radiographical methods can be used to detect hypoxia. Therapeutic approaches that target chronic hypoxia in the kidney should be effective against a broad range of kidney diseases. Amelioration of hypoxia is one mechanism of inhibiting the renin-angiotensin system, the current gold standard of CKD therapy. Future therapeutic approaches include protection of the vascular endothelium and appropriate activation of hypoxia-inducible factor, a key transcription factor involved in adaptive responses against hypoxia.

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.

Effect of Hyperbaric Oxygen on Cyclosporine-Induced Nephrotoxicity and Oxidative Stress in Rats

Reactive oxygen species have been suggested to be involved in cyclosporine nephrotoxicity. Hyperbaric oxygen is known to induce the generation of reactive oxygen species in tissues. The aim of this study was to investigate whether the use of hyperbaric oxygen concurrently with cyclosporine potentiates cyclosporine nephrotoxicity by inducing oxidative stress in kidneys. The study consisted of four groups of rats: a control group, a cyclosporine group (15 mg/kg/day intraperitoneally for 14 days), a hyperbaric oxygen group (60 min. every day for five days at 2.5 atmosphere absolute), and a cyclosporine + hyperbaric oxygen group (cyclosporine 15 mg/kg/day intraperitoneally for 14 days + hyperbaric oxygen for 60 min at 2.5 atmosphere absolute every day for five days on the last five days of cyclosporine treatment). Oxidative stress was determined by measuring renal thiobarbituric acid-reactive substances content, renal superoxide dismutase, and glutathione peroxidase activities. Cyclosporine increased serum urea and creatinine levels, indicating the development of nephrotoxicity, and induced significant oxidative stress in rat kidneys. Hyperbaric oxygen alone did not alter any of the biochemical and oxidative stress parameters compared to the control group. When used concurrently with cyclosporine, hyperbaric oxygen significantly reduced cyclosporine-induced oxidative stress, but it neither attenuated nor aggravated cyclosporine-induced nephrotoxicity. These results suggest that reactive oxygen species are involved in cyclosporine nephrotoxicity, but are not the direct cause of the toxicity. Although concurrent use of cyclosporine and hyperbaric oxygen did not exacerbate cyclosporine nephrotoxicity in this model, we recommend that the renal functions of patients be monitored periodically when these treatments are used concurrently.

Hyperbaric oxygen treatment improves GFR in rats with ischaemia/reperfusion renal injury: a possible role for the antioxidant/oxidant balance in the ischaemic kidney

BACKGROUND

Ischaemic kidney injury continues to play a dominant role in the pathogenesis of acute renal failure (ARF) in many surgical and medical settings. A major event in the induction of renal injury is related to the generation of oxygen-free radicals. Hyperbaric oxygen therapy (HBO) is indicated for treatment of many ischaemic events but not for ARF. Therefore, the present study examined the effects of HBO on kidney function and renal haemodynamics in rats with ischaemic ARF.

METHODS

Renal ischaemia was induced by unilateral renal artery clamping (45 min) in rats. Within 24 h following ischaemia, rats were treated twice with HBO of 100% O(2) at 2.5 absolute atmospheres for 90 min each (+HBO). Untreated rats (-HBO) served as a control. Forty-eight hours later, GFR, RBF and endothelial-dependent vasorelaxation were measured. In addition, the immunoreactive staining of 4-hydroxy-2-noneal (4-HNE), a major product of endogenous lipid peroxidation, and superoxide dismutase (SOD) were assessed.

RESULTS

In the -HBO group, GFR was reduced by 94% compared with the untouched normal kidney (ischaemic: 0.06 +/- 0.03 ml/min, normal: 1.02 +/- 0.13 ml). In contrast, in the +HBO group, GFR of the ischaemic kidney (0.36 +/- 0.07 ml/min) was reduced only by 68% compared with the contralateral normal kidney (1.12 +/- 0.12 ml/min). In line with these findings, HBO improved the vasodilatory response to ACh as expressed in enhancement of both total and regional renal blood flow. In addition, HBO reduced the formation of 4-HNE by 33% and 76% and increased SOD by 30% and 70% in the cortex and outer stripe region of the medulla of the ischaemic kidney, respectively.

CONCLUSION

HBO attenuates the decline in GFR following renal ischaemia, and improves endothelial-dependent vasorelaxation, suggesting that treatment with HBO may be beneficial in the setting of ischaemic ARF.

Hyperbaric oxygen treatment augments the efficacy of cilazapril and simvastatin regimens in an experimental nephrotic syndrome model

BACKGROUND

Oxidative stress plays a role in the mechanism of chronic kidney disease (CKD), and antioxidant regimes are regarded as promising treatment modalities. We compared the effects of cilazapril, simvastatin, and hyperbaric oxygen (HBO) treatment on proteinuria and on oxidative stress in adriamycine (ADR)-induced proteinuria.

METHODS

Seventy male Sprague-Dawley rats were housed, and 60 were injected with ADR to induce nephrosis. After the stabilization of proteinuria, rats were treated for 6 weeks with simvastatin (n = 10, 4 mg/kg/day), cilazapril (n = 10, 10 mg/kg/day), HBO (n = 10, 2.8 athmosphere absolute, 90 min/daily), HBO + cilazapril (n = 10), HBO + simvastatin (n = 10), and vehicle (n = 10). After euthanization at 12 weeks, protein carbonyl (PCO), superoxide dismutase (SOD), and glutathion peroxidase (GPx) levels were analyzed from tissues. The histological alterations in the kidneys were determined by semiquantitative scoring.

RESULTS

Protein carbonyl (PCO) levels were higher (p < 0.001), and the GPx and SOD levels were lower (p < 0.001 for all) in the nephrotic rats. Proteinuria was correlated to PCO (r = 0.483), GPx (r = -0.686), or SOD (r = -0.620) (p < 0.001 for all). Superoxide dismutase (SOD) (beta = -0.381, p = 0.02) and GPx (beta = -0.509, p < 0.001) were independently related to proteinuria levels. Both cilazapril and simvastatin significantly improved GPx, SOD, PCO, and proteinuria. When HBO was combined with either drug, the above markers further improved (p < 0.001). Both regimens caused distinct histological features, while the combination of HBO made much significant histological improvement.

CONCLUSION

Both cilazapril and simvastatin regimens improve oxidative stress and proteinuria, while the effects significantly increase with the combination of HBO treatment. HBO seems to be a candidate antioxidant strategy in glomerular diseases.

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.