[Quantitative study of therapeutic efficacy on early intervention of hyperbaric oxygen to model of steroid-induced avascular osteonecrosis of femoral head by multi-slice perfusion imaging].

OBJECTIVE: To quantitatively evaluate the hemodynamic status in animal models of steroid-induced avascular osteonecrosis of femoral head (SANFH) by multislice CT (MSCT) perfusion imaging, and estimate the therapeutic efficacy on early intervention of hyperbaric oxygen (HBO) to improve the region blood flow (rBF) of ischemic femoral head. METHODS: Forty-eight New Zealand male rabbits were injected with Escherichia coli endotoxin and methyl-prednisolone to establish SANFH models and then divided into 3 subgroups to undergo MSCT to measure the rBF, regional blood volume (rBV), and mean transit time (MTT) to obtain perfusion maps at the femoral head epiphysis, metaphysic, and neck of femur, and then were killed to undergo histological examination of the bilateral femoral heads 2, 4, and 6 weeks later respectively (Groups M(2), M(4), and M(6)). Twenty-four rabbits underwent HOB treatment after the second injection of E. c. endotoxin for 1-3 courses respectively (Groups H(1), H(2), and H(3)), and then underwent MSCT and pathological examination as described above. Eight rabbits were used as controls (Group N). RESULTS: (1) The rBF values of Groups M(2), M(4), and M(6) were all significantly lower than that of Group N (P < 0.001, < 0.001, and < 0.002). The rBF value of femoral head epiphysis of Group M(2) was remarkably lower than that of Group N, decreased to the lowest in Group M(4), and re-increased in Group M(6). The rBV value demonstrated similar change pattern in femoral head epiphysis. The MTT values of Groups M(2) and M(4) were longer than that of Group N, and then re-decreased in Group M(6). (2) It did differ significantly between the perfusion data of different femoral head anatomic regions in Groups M(2), M(4), M(6) and N (rBF: F = 52.190, P < 0.001; rBV: F = 42.677, P < 0.001; MTT: F = 3.09, P = 0.048). The changes of the perfusion data in femoral head epiphysis were more significant than those in other anatomic regions. (3) There were no statistically significant differences in the rBF value of the femoral head epiphysis and metaphysis (F = 2.081, P = 0.115; F = 1.142, P = 0.341), in the rBV value of the femoral metaphysis and neck of femur (F = 2.642, P = 0.059; F = 1.568, P = 0.209), and the MTT value of all the anatomic regions (F = 1.111, P = 0.347) among Groups H(1), H(2), H(3), and N. The rBF values of Groups H(1), H(2), and H(3) were statistically higher than those of the corresponding phase model groups (all P < 0.05). CONCLUSIONS: Able to detect hemodynamic status of femoral head, MSCT perfusion imaging technique may be used in the early detection of SANFH. Early intervention of HBO therapy can improve the blood perfusion of femoral head.

[The therapeutic effect of small dose of estrogen on cerebral infarction].

OBJECTIVE: To investigate the mechanism of protective effect of estrogen on cerebral damage in ischemic stroke by measuring the estrogen(2) (E(2)), blood lipid, interleukin-1 beta (IL-1 beta), nitric oxide (NO), and also assessment according to national institute of health stroke scale (NIHSS) score, in order to improve the treatment of cerebral infarction. METHODS: Forty male patients, in whom cerebral infarction due to thrombosis of middle cerebral artery was confirmed by CT or magnetic resonance imaging (MRI), were divided into two groups: E(2) therapy (20 cases) and routine therapy (20 cases). Routine therapy was the same in both groups, except 2 mg of E(2) was orally given (2 times a day) to the E(2) therapy group. E(2), testosterone (Ts), total cholesterol (TC), triglyceride (TG), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), IL-1 beta, NO, and NIHSS score were measured in each patient at time points of 0, 3, 7, 14 and 21 days. RESULTS: In E(2) group, HDL-C and E(2) were increased significantly, and TC and LDL-C were decreased significantly from 3 days on after treatment, and the changes were obviously more marked than that of routine therapy group (all P<0.05). The changes in TG and Ts were not obvious. NO, IL-1 beta were increased significantly (both P<0.05), and NIHSS score was decreased in routine group form 14 days on after treatment. NO and IL-beta in E(2) group were lower than those in routine therapy group from 3 days on, and the NIHSS score was significantly lower on 14 days and 21 days in E(2) group (both P<0.05). CONCLUSION: The protective effect of E(2) is obvious. It may be due to the results of modulation of blood fat, anti-inflammation and modulation of NO production by the action of E(2). Low dose and short time therapy of E(2) may be beneficial to the patient.

Hyperbaric oxygen intervention reduces secondary spinal cord injury in rats via regulation of HMGB1/TLR4/NF-κB signaling pathway.

BACKGROUND: To investigate whether hyperbaric oxygen (HBO) intervention affects the expressions of inflammatory cytokines, HMGB1/TLR4/NF-κB, and arrests secondary spinal cord injury (SCI). METHODS: One hundred and twenty healthy adult SD rats were randomly divided into four groups: sham, sham + HBO, SCI, and SCI + HBO. Each group was then randomly divided into five subgroups of 6 rats each according to the following time points: 1, 2, 3, 7, and 14 d post injury. Functional recovery of the hindlimb was assessed by Basso, Beattie, and Bresnahan (BBB) scores at different time points after SCI. The expression of HMGB1, TLR4, and NF-κB in the spinal cord tissue was determined by fluorescence quantitative PCR, western blot, immunohistochemistry, and ELISA. RESULTS: The gene expressions of TLR4, HMGB1, and NF-κB (P < 0.01) and the TLR4 protein expression were significantly high after SCI. HBO intervention significantly decreased all the four parameters at 3, 7, and 14 d post injury (P < 0.05). A significant positive correlation (P < 0.01) was observed between the following: HMGB1 mRNA, TLR4 mRNA and TLR4 protein; HMGB1 mRNA and NF-κB mRNA; and TLR4 protein and NF-κB mRNA. BBB score was negatively correlated with HMGB1, TLR4 protein and NF-κB levels. HBO intervention significantly improved the BBB scores at 7 and 14 d post injury (P < 0.05). CONCLUSIONS: Hyperbaric oxygen reduced the expressions of HMGB1, TLR4, and NF-κB and reduced secondary SCI as measured using BBB scores.

[Study of platelet membrane glycoprotein expression in mice with decompression sickness].

OBJECTIVE: To investigate the role of expression of platelet membrane glycoprotein CD31, CD61 and CD62p in the pathogenesis of decompression sickness. METHODS: Mice were randomly divided into decompression sickness group and normal control group. The animals in decompression sickness group were exposed to 600 kPa compressed air for 60 minute, then they were rapidly decompressed to normal pressure in one minute. At 60th minute after reducing to normal pressure, the expression of CD31, CD61 and CD62p on platelet membrane in mice was measured by flow cytometry. RESULTS: The mean fluorescence intensity of CD31, CD61 and positive percentage of CD62p on platelet membrane [(18.64 +/- 1.01), (271.06 +/- 24.25), (4.48% +/- 0.43%) respectively] in decompression sickness group were significantly increased compared with normal control group [(16.89 +/- 1.69), (234.09 +/- 15.96), (3.00% +/- 0.66%) respectively] (P < 0.05, P < 0.01). CONCLUSION: Inadequately rapid decompression may induce up regulation of platelet membrane glycoprotein CD31, CD61 and CD62p expression in mice, which may lead to thrombosis.

Preconditioned hyperbaric oxygenation protects skin flap grafts in rats against ischemia/reperfusion injury.

Hyperbaric oxygen (HBO) therapy is an effective therapy for ischemia/reperfusion (I/R) injury of the brain, small intestine, testes and liver. However, the detailed molecular mechanisms underlying the effect of HBO therapy remain undetermined. In the current study, the hypothesis that preconditioning rats with HBO protects grafted skin flaps against subsequent I/R injury was investigated. In addition, the molecular mechanisms underlying HBO therapy were characterized by analyzing the roles of the following important inflammatory factors: High mobility group protein 1 (HMGB1) and nuclear factor-κ B (NF-κB). A total of 40 rats were randomly divided into the following five groups: (i) Sham surgery (SH); (ii) ischemia followed by reperfusion 3 days following surgery (I/R3d); (iii) ischemia followed by reperfusion 5 days following surgery (I/R5d); (iv) HBO preconditioning (HBO-PC) and ischemia followed by reperfusion 3 days following surgery (HBO-PC+3d); and (v) HBO-PC and ischemia followed by reperfusion 5 days following surgery (HBO-PC+5d). For the surgical procedure, all pedicled skin flaps were first measured and elevated (9x6 cm). The feeding vessels of the skin flaps were subsequently clamped for 3 h and released to restore blood flow. The rats in the HBO-PC+3d and HBO-PC+5d groups received 1 h HBO for 3 and 5 consecutive days, respectively, prior to surgery. Following surgery, the rats were euthanized, and grafted tissues were collected for western blotting and immunohistochemistry. HBO-PC increased blood perfusion in epigastric skin flaps and attenuated I/R injury following skin flap graft. Additionally, the elevated expression of HMGB1 and NF-κB proteins during I/R injury was attenuated by HBO-PC treatment. HBO-PC may therefore be applied to reduce I/R injury and improve the survival rate of grafted skin flaps. The molecular mechanisms underlying the effect of HBO therapy are associated with the attenuation of inflammatory responses.

Hyperbaric oxygen intervention on expression of hypoxia-inducible factor-1α and vascular endothelial growth factor in spinal cord injury models in rats.

BACKGROUND: Hyperbaric oxygen (HBO) intervention is a main therapeutic method and the curative effect has been certified for spinal cord injury (SCI), but the mechanisms of the neuroprotective effect of HBO on SCI remain elusive. This study aimed to observe the change in expression of hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) after SCI at different time points and to investigate the neuroprotective mechanism of HBO on SCI in rats. METHODS: A total of 160 adult Sprague-Dawley rats, weighing between 250 and 300 g, were randomly assigned to four experimental groups (n = 40 per group). SCI group: SCI was created with a special NYU impactor of Allen's by a 25 gramcentimeter impacting energy on T10 of the spinal cord. SCI+HBO group: HBO therapy after SCI model was established. Sham operation (SH) group: only laminectomy of T10 and no impact on the spinal cord was done. SH+HBO group: HBO therapy after sham operation. The hindlimb functional recovery was evaluated using Basso, Beattie, and Bresnahan (BBB) score and the expressions of HIF-1α and VEGF were observed with fluorescent quantitation PCR and Western blotting method of six rats picked randomly from each group at different time points of 1, 3, 7, and 14 days after operation. RESULTS: Rats in the SCI group and SCI+HBO group were paralyzed completely after operation with BBB 0-1 score. Rats in the SH group and SH+HBO group could walk after sham operation with BBB 20-21 score. The BBB score of rats in the SCI+HBO group (4.67±1.97 and 10.83±2.23) was higher than that in the SCI group (1.83±0.75 and 6.67±2.16) at 7 and 14 days time points obviously (P < 0.05). The expressions of HIF-1a and VEGF in the SCI group and SCI+HBO group were higher than in the SH group and SH+HBO group at any time point obviously (P < 0.05), while the SCI+HBO group presented the least expression of HIF-1α mRNA and protein (3.82±0.41 and 0.59±0.06; 2.26±0.41 and 0.37±0.05; 1.58±0.26 and 0.29±0.05) than that in the SCI group (6.36±0.58 and 0.76±0.07; 3.55±0.47 and 0.51±0.07; 2.27±0.39 and 0.40±0.06) respectively at 3, 7, and 14 days time points (P < 0.05) with significant difference and more expression of VEGF mRNA and protein (5.83±0.77 and 0.72±0.06; 4.59±0.51 and 0.63±0.06) than that in the SCI group (3.06±0.30 and 0.48±0.07; 2.25±0.24 and 0.39±0.09) respectively at 7 and 14 days time points (P < 0.05) with significant difference. CONCLUSIONS: HBO could improve the hind limb functional recovery after SCI in rats. The elevation and duration of the expression of VEGF and the reduction of expression of HIF-1α by HBO intervention may be inversely related in the repair of damaged spinal cord and neuroprotective effect.

Effects of hyperbaric oxygen preconditioning on ischemia-reperfusion inflammation and skin flap survival.

BACKGROUND: Hyperbaric oxygen preconditioning (HBO) is a new method of ischemia preconditioning. In this study, we examined its effects on skin flap survival and the mechanisms involved. METHODS: Thirty-six rats were divided into three groups: HBO preconditioning, control, and sham groups. An extended epigastric adipocutaneous flap based on the right superficial epigastric artery and vein was raised. A 3-hour period of flap ischemia was induced by clamping the pedicle vessels with a microvascular clamp. At the end of ischemia induction, the clamp was removed and the flap was resutured. Rats in the HBO preconditioning group were treated with HBO four times before surgery. Microcirculation in the skin flap was measured on postoperative days 1, 3 and 5. The size of the flap was measured on postoperative day 5, before the animals were sacrificed. Samples of the skin flap were prepared and stained with hematoxylin and eosin. The levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, and IL-6 in the flap samples were measured. RESULTS: Surviving flap size was significantly higher in the HBO preconditioning group compared with controls, with a reduced inflammatory response and increased perfusion. IL-1, TNF-α, and IL-6 levels in the HBO preconditioning group were lower than in controls. CONCLUSIONS: HBO preconditioning improved flap survival in this ischemia-reperfusion rat model. The mechanisms responsible for this effect may relate to attenuation of the inflammatory response and increased flap perfusion following HBO preconditioning.

Resuscitation from experimental heatstroke by hyperbaric oxygen therapy.

OBJECTIVE: Heatstroke is characterized by hyperthermia, vasoplegic shock, and cerebral ischemia and hypoxia. Hyperbaric oxygen (HBO) has been shown to reduce brain ischemia and behavioral dysfunction during cerebral artery occlusion. The efficacy of HBO therapy for resuscitation from heatstroke remains to be determined in the laboratory. DESIGN: Anesthetized rats were randomized to several groups and administered: 1) no resuscitation (normobaric air) after onset of heatstroke, 2) HBO for 1 hr (100% oxygen at 253 kPa for 1 hr), 3) cyclic HBO intermitted by a 5-min air break for 1 hr of treatment (100% oxygen at 253 kPa), 4) hyperbaric air (air at 253 kPa for 1 hr), 5) normobaric hyperoxia (100% oxygen at 101 kPa for 1 hr), or 6) 8% HBO (hyperbaric 8% oxygen at 253 kPa for 1 hr). SETTING: Laboratory investigation. SUBJECTS: Sprague-Dawley rats (300- to 400-g males). INTERVENTIONS: Rats were exposed to an ambient temperature of 43 degrees C to induce heatstroke. Their colonic temperature; mean arterial pressure; heart rate; arterial blood levels of pH, Paco2, Pao2, So2%, and tumor necrosis factor-alpha; the cortical levels of ischemic and damage markers, and cortical neuronal damage scores were determined. The moment at which mean arterial pressure began to decrease from peak levels was arbitrarily taken as the onset of heatstroke. MAIN RESULTS: Survival time (interval between onset of heatstroke and animal death) was 19 +/- 1 (n = 10), 131 +/- 18 (n = 14), 159 +/- 28 (n = 13), 72 +/- 14 (n = 10), 68 +/- 12 (n = 10), and 45 +/- 11 (n = 10) mins, respectively, for normobaric air, HBO for 1 hr, cyclic HBO, hyperbaric air, normobaric hyperoxia, and 8% HBO groups. The heatstroke induced arterial hypotension and bradycardia, decreased arterial levels of pH, Pao2, and So2%, increased arterial levels of tumor necrosis factor-alpha, and increased values of cellular ischemia and damage markers. In addition, neuronal damage scores in the cortex were significantly reduced by HBO for 1 hr and cyclic HBO resuscitation. CONCLUSION: We successfully demonstrated that HBO and, to some extent, hyperbaric air, normobaric hyperoxia, or HBO 8% was found beneficial in resuscitating rats with experimental heatstroke. HBO effectively reduced heatstroke-induced arterial hypotension, hypoxia, plasma tumor necrosis factor-alpha overproduction, and cerebral ischemia and damage and improved survival.