Hyperoxygenated solution improves tissue viability in an avulsion injury flap model

BACKGROUND

Management of avulsion injuries remains a challenge due to necrosis. The aim of the present study is to create an experimental model reproducing an avulsion injury and investigate the effects of hyperoxygenated solution (HOS), a method of oxygen delivery that has been widely used in the therapy of ischaemia-hypoxia diseases, on avulsion injury flap survival in rats.

METHODS

Forty male rats were divided into four groups (n = 10 each). Dorsal random pattern flaps measuring 3 × 9 cm, including the panniculus carnosus, were elevated and run over by the skin avulsion model machine, and the flaps were then sutured into their original places. The sham+HOS and avulsion+HOS groups received intravenous HOS (20 ml/kg) each day for 7 days after the operation. The sham+saline and avulsion+saline groups received intravenous saline solution (20 ml/kg) each day for 7 days after the operation. Percutaneous O₂ pressure (TcpO₂) measurement_, serial examinations of skin flap blood perfusion, skin flap survival evaluation and histopathology were performed to assess the efficacy of HOS on avulsion injury.

RESULTS

Compared to the avulsion+saline groups, TcpO₂ was significantly higher in the avulsion+HOS groups at 15, 30 and 60 min after infusion (P < 0.05). The blood perfusion of flaps in the avulsion+HOS group was higher than in the avulsion+saline group (P < 0.05). The survival rate was higher in the avulsion+HOS group than in the avulsion+saline group (P < 0.05), and the histopathology assays supported the data.

CONCLUSION

We succeeded in developing an avulsion injury model and demonstrated that HOS could improve the survival of the avulsion injury flaps in rats by effectively increasing the local oxygen content and blood perfusion and ameliorating inflammatory damage.

Hyperoxygenated Hydrogen-Rich Solution Suppresses Lung Injury Induced by Hemorrhagic Shock in Rats

BACKGROUND

Hemorrhagic shock could induce acute lung injury (ALI), which is associated with cell hypoxia, lung tissue inflammation, free radical damage, and excessive cell apoptosis. Our previous studies demonstrated that hyperoxygenated solution could alleviate cell hypoxia. Furthermore, hydrogen-rich solution (HS) could relieve lung tissue inflammation, free radical damage and excessive cell apoptosis. Therefore we hypothesize that Hyperoxygenated Hydrogen-rich solution (HOHS) can protect the lung against ALI.

MATERIALS AND METHODS

SD rats were randomly divided into five groups (n = 6 at each time point in each group) and were exposed to Hemorrhagic shock induced ALI, and then treated with lactated Ringer's solution (LRS), hyperoxygenated solution, HS, and HOHS, respectively. The protective effects of these solutions were assessed using methods as follows: arterial blood samples were collected for blood gas analysis; Bronchoalveolar lavage fluid was collected for cell count and protein quantification; lung tissue samples were collected to measure wet/dry ratio, as well as levels of T-SOD, MDA, TNF-α, and IL-6; Caspase-3 and TUNEL-positive cells, and pathological changes were observed under light microscope; ALI was scored using the Smith scoring method; ultrastructural changes of lung tissues were further observed with transmission electron microscopy.

RESULTS

The results indicated that PaO2, PaCO2, and T-SOD increased in the three treatment groups (P < 0.05), most significantly in the HOHS group (P < 0.01) compared with the LRS group; and conversely that the levels of lactate, MDA, TNF-α and IL-6, cell count, protein content, caspase-3 and TUNEL-positive cells as well as ALI score decreased in the three treatment groups (P < 0.05), most significantly in the HOHS group (P < 0.01) compared with the LRS group. Morphological observation with optical microscope and electron microscopy showed that compared with the LRS group, cell damage in the three treatment groups improved to a varying extent, especially evident in the HOHS group.

CONCLUSIONS

These findings demonstrate that HOHS can protect the lung against ALI induced by hemorrhagic shock.

Induction of heme oxygenase-1 by hemin protects lung against orthotopic autologous liver transplantation-induced acute lung injury in rats

BACKGROUND

Post-liver transplantation acute lung injury (ALI) severely affects patients' survival, whereas the mechanism is unclear and effective therapy is lacking. The authors postulated that reperfusion-induced increased oxidative stress plays a critical role in mediating post-liver transplantation ALI and that induction of heme oxgenase-1 (HO-1), an enzyme with anti-oxidative stress properties, can confer effective protection of lung against ALI.

METHODS

Male Sprague-Dawley rats underwent autologous orthotopic liver transplantation (OALT) in the absence or presence of treatments with the selective HO-1 inducer (Hemin) or HO-1 inhibitor (ZnPP). Lung tissues were collected at 8 h after OALT, pathological scores and lung water content were evaluated; survival rate of rats was analyzed; protein expression of HO-1 was determined by western blotting, and nuclear translocation of Nuclear factor erythroid 2-related factor 2 (Nrf2) and nuclear factor(NF)-κB p65 were detected by Immunofluorescence staining. The inflammatory cytokines and oxidative indexes of lung tissue were determined.

RESULTS

In lungs harvested at the early stage i.e. 8 h after OALT, Hemin treatment significantly increased superoxide dismutase activities, and reduced malondialdehyde, hydrogen peroxide, interleukin-6, myeloperoxidase, and tumor necrosis factor-α production,which were associated with increased HO-1 protein expression and lower pathological scores and increased survival rate of rats. The underline mechanisms might associate with activation of Nrf2 and inhibition of NF-κB p65 nuclear translocation. However, these changes were aggravated by ZnPP.

CONCLUSIONS

Hemin pretreatment, by enhancing HO-1 induction, increased lung antioxidant capacity and reduced inflammatory stress,protected the lung from OALT-induced ALI at early stage of reperfusion.

Ulinastatin prevents acute lung injury led by liver transplantation

BACKGROUND

Little is known regarding the effect of ulinastatin (UTI) on acute lung injury (ALI) induced by orthotopic liver transplantation. This study aims to investigate the protective effect of UTI on ALI induced by orthotopic autologous liver transplantation (OALT) in a rat model and to explore the potential underlying mechanism.

MATERIALS AND METHODS

Rats were randomly allocated into the following four groups (n = 8 each): (i) sham control group (group sham); (ii) model group (underwent OALT) (group model); (iii) low-dose UTI-treated group (group u1), with UTI (50 U/g) administered intravenously both before the portal vein was occluded and after liver reperfusion started; and (iv) high-dose UTI-treated group (group uh), with UTI (100 U/g) given in the same way as group ul. The lung pathologic parameters, lung water content, and levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, malondialdehyde (MDA), superoxide dismutase (SOD) activity, RanBP-type and C3HC4-type zinc finger-containing protein 1 (RBCK1), and peroxiredoxin-2 (Prx-2) were assessed 8 h after OALT was performed.

RESULTS

According to histology, there was severe damage in the lung of group model accompanied by increases in the TNF-α, IL-1β, IL-6, and MDA levels and decreases in SOD activity and the expression of RBCK1 and Prx-2. UTI treatment significantly reduced the pathologic scores, lung water content, and TNF-α, IL-1β, IL-6, and MDA levels while restoring the SOD activity and expression of RBCK1 and Prx-2. Furthermore, compared with group u1, treatment with a high dose of UTI resulted in a better protective effect on the lung when assessed by the TNF-α, IL-1β, IL-6, and MDA levels and SOD activity.

CONCLUSIONS

UTI dose-dependently attenuates ALI that is induced by OALT in this rat model, which is mainly due to the suppression of the inflammatory response and oxidant stress, which may, in turn, be mediated by the upregulation of RBCK1 and Prx-2 expression.

Propofol activation of the Nrf2 pathway is associated with amelioration of acute lung injury in a rat liver transplantation model

Objective. This study aimed to investigate whether propofol pretreatment can protect against liver transplantation-induced acute lung injury (ALI) and to explore whether Nrf2 pathway is involved in the protections provided by propofol pretreatment. Method. Adult male Sprague-Dawley rats were divided into five groups based on the random number table. Lung pathology was observed by optical microscopy. Lung water content was assessed by wet/dry ratio, and PaO₂ was detected by blood gas analysis. The contents of H₂O₂, MDA, and SOD activity were determined by ELISA method, and the expression of HO-1, NQO1, Keap1, and nuclear Nrf2 was assayed by western blotting. Results. Compared with saline-treated model group, both propofol and N-acetylcysteine pretreatment can reduce the acute lung injury caused by orthotopic autologous liver transplantation (OALT), decrease the lung injury scores, lung water content, and H₂O₂ and MDA levels, and improve the arterial PaO₂ and SOD activity. Furthermore, propofol (but not N-acetylcysteine) pretreatment especially in high dose inhibited the expression of Keap1 and induced translocation of Nrf2 into the nucleus to further upregulate the expression of HO-1 and NQO1 downstream. Conclusion. Pretreatment with propofol is associated with attenuation of OALT-induced ALI, and the Nrf2 pathway is involved in the antioxidative processes.

Potential use of hyperoxygenated solution as a treatment strategy for carbon monoxide poisoning

Aim

Carbon monoxide (CO) poisoning can cause permanent damage in tissues that are sensitive to hypoxia. We explored the feasibility and efficacy of using a hyperoxygenated solution (HOS) to treat severe acute CO poisoning in an animal model.

Methods

Male Sprague-Dawley rats were subjected to CO poisoning. The HOS was administered into the femoral vein of these rats through a catheter (10 ml/kg). Carboxyhemoglobin (COHb) and blood gases were used to assess the early damage caused by CO poisoning. S100β was measured to predict the development of late cognitive sequelae of CO. The Morris water maze test was performed to assess cognitive function, and Nissl staining was performed to observe histologic change.

Results

The COHb concentrations rapidly decreased at 5 min after the HOS administration; however, the PaO₂ and SaO₂ in rats treated with HOS increased significantly 5 min after the HOS administration. The S100β concentrations, which increased significantly after CO poisoning, increased at a much slower rate in the rats treated with HOS (HOS group) compared with the rats treated with O₂ inhalation (O₂ group). The escape latency in the place navigation test was shortened after CO poisoning on days 11-15 and days 26-30, and the swimming time in quadrant 4 in the spatial probe test on days 15 and 30 after CO poisoning was prolonged in the rats treated with HOS injection compared with the rats treated with oxygen inhalation or normal saline injection. The neuronal degeneration in the HOS group was alleviated than that in the CO or O₂ group.

Conclusion

HOS efficiently alleviates the brain damage in acute CO-poisoned rats and thus may serve as a new way to treat human patients with CO poisoning in clinical practice.

Knockdown of myeloid differentiation protein-2 reduces acute lung injury following orthotopic autologous liver transplantation in a rat model

BACKGROUND

Acute lung injury (ALI) is a serious complication that commonly occurs during orthotopic liver transplantation (OLT). Toll-like receptor 2/4 (TLR2/4) are the main membrane receptors that respond to inflammatory stimuli and mediate NF-kappa B (NF-κB) signal pathway. We previously showed that TLR2/4 expression on monocytes and serum cytokine levels were increased in patients with ALI induced by OLT. Myeloid differentiation protein-2 (MD-2) expresses the functional domains that combines TLRs and play a key regulatory role in TLRs activation. Therefore, we hypothesized that blocking MD-2 would inhibit the TLR2/4-mediated inflammatory response and lessen ALI induced by liver transplantation.

METHOD

Thirty-two Sprague Dawley (SD) rats were randomly divided into four groups. One group received a sham operation (Group S), and the other three groups underwent orthotopic autologous liver transplantation (OALT) 48 h after intratracheal administration of saline (Model group; Group M), non-targeting siRNA (negative siRNA control group; Group NC) or siRNA against MD-2 (intervention group; Group RNAi). Lung pathology, lung water content, PaO2, and expression levels of MD-2, TLR2/4, NF-κB, TNF-α, IL-1β and IL-6 were assessed 8 h after OALT.

RESULTS

In Groups M and NC, OALT produced marked lung pathology with decreased PaO2 levels and increased MD-2, TLR2/4 gene and protein expression levels. Furthermore, the nuclear translocation of the NF-κB P65 subunit, was increased, as were lung concentrations of TNF-α, IL-1β and IL-6. The pathology of ALI and the severity of the above biochemical changes induced by OALT were significantly reduced in the group treated with MD-2 siRNA.

CONCLUSION

MD-2 gene knock-down attenuated the increase in TLR2/4 activation and reduced ALI after OALT.

Hyperoxygenated solutions in clinical practice: preventing or reducing hypoxic injury

In cases of hypoxia, oxygen can be supplied via a number of methods including face masks, nasal cannulae, hyperoxygenated oxygen chambers and mechanical ventilation. Administering oxygen via the respiratory tract is, however, limited in respiratory diseases such as pulmonary fibrosis, pneumoconiosis and severe acute respiratory syndrome, or following the inhalation of asphyxiating poisons. This has led to research into new methods of supplying oxygen that bypass the lungs. Research has investigated the efficacy of intravenous hyperoxygenated solutions (HOS) as auxiliary oxygen supplies in several hypoxic states including cardiopulmonary resuscitation, respiratory failure, cerebrovascular disease, myocardial ischaemia, severe acute respiratory syndrome, poisoning, neonatal hypoxia, altitude sickness, large burns and traumatic haemorrhagic shock. Much of the research has taken place in China and more than 3.5 million hypoxic patients have received HOS, with good therapeutic effects. This review summarizes the literature supporting the use of this novel treatment.

Hyperoxygenated solution: effects on acute hypobaric hypoxia-induced oxidative damage in rabbits

High altitude (HA) exposure disrupts the efficiency of the antioxidant system and can lead to oxidative damage in various organs and tissues. The present study investigated the effect of hyperoxygenated solution (HOS) intravenous infusion therapy on oxidative damage induced by acute hypobaric hypoxia. Experimental rabbits were exposed to a simulated high altitude (HA), equivalent to 8500 m, in an animal decompression chamber for 3 h. HOS infusion attenuated the rise in malondialdehyde (MDA) levels and the decrease of the reduced oxidized glutathione (GSH/GSSG) ratio. HOS also increased the activity of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px); the arterial partial pressure of oxygen (Pao(2)); and arterial blood oxygen saturation (Sao(2)) levels. Animals treated with HOS had higher Pao(2) compared with those subjected to airway oxygen therapy (p < 0.01) during HA exposure. These observations suggest that HOS intravenous infusion exerts protective effects against acute hypobaric hypoxia-induced oxidative damage.