Ischemic preconditioning attenuates pulmonary dysfunction after unilateral thigh tourniquet-induced ischemia-reperfusion.

BACKGROUND: Acute lung injury is a recognized complication of lower limb ischemia-reperfusion that has been demonstrated experimentally and in the clinical setting of aortic surgery. The application of a tourniquet can cause lower limb ischemia-reperfusion in orthopedic surgery. We studied the effect of unilateral thigh tourniquet-induced lower limb ischemia-reperfusion on pulmonary function, and the role of ischemic preconditioning in attenuating pulmonary dysfunction. METHODS: Thirty ASA I or II patients scheduled for lower extremity surgery were randomized into 2 groups: a limb ischemia-reperfusion group with tourniquet application (ischemia-reperfusion group, n = 15) and an ischemia preconditioning group (preconditioning group, n = 15), in which patients received 3 cycles of 5 minutes of ischemia, alternating with 5 minutes of reperfusion before extended use of the tourniquet. Blood gas, plasma malondialdehyde, and serum interleukin-6 (IL-6), IL-8, and IL-10 levels were measured just before tourniquet inflation, 1 hour after inflation and 2 hours, 6 hours, and 24 hours after tourniquet deflation. Arterial-alveolar oxygen tension ratio, alveolar-arterial oxygen tension difference, and respiratory index also were calculated. RESULTS: In comparison with the baseline values, arterial Po(2) and arterial-alveolar oxygen tension ratio were decreased, while alveolar-arterial oxygen tension difference and respiratory index were increased significantly 6 hours after tourniquet deflation in both groups (P < 0.01). However, these changes were less significant in the ischemic preconditioning group than those in the lower limb ischemia-reperfusion group (P < 0.01). Similarly, the increases in the malondialdehyde, IL-6, and IL-8 from 2 hours to 24 hours after release of the tourniquet in the lower limb ischemia-reperfusion group were attenuated by ischemic preconditioning. CONCLUSIONS: Pulmonary gas exchange is impaired after lower limb ischemia-reperfusion associated with the clinical use of a tourniquet for lower limb surgery. Ischemic preconditioning preceding tourniquet-induced ischemia attenuates lipid peroxidation and systemic inflammatory response and mitigates pulmonary dysfunction.

Effect of two administration routes of Shenmai Injection () on pulmonary gas exchange function after tourniquet-induced ischemia-reperfusion.

OBJECTIVE: To compare the effect between nebulized and intravenous administration of Shenmai Injection () on pulmonary gas exchange function of patients following tourniquet-induced lower limb ischemia-reperfusion. METHODS: Thirty-eight patients scheduled for lower extremity surgery were randomized into three groups using the closed envelop method: Shenmai Injection was administered 30 min before tourniquet inflflation by nebulization [0.6 mL/kg in 10 mL normal saline (NS)] in the nebulization group or by intravenous drip (0.6 mL/kg dissolved in 250 mL of 10% glucose) in the intravenous drip group, and equal volume of NS was given intravenously in the NS group; 15 in each group. Arterial blood gases were analyzed, serum levels of malonaldehyde (MDA) and interleukine-6 (IL-6) and interleukine-8 (IL-8) were determined using the method of thiobarbituric acid reaction and enzyme-linked immuno sorbent assay respectively just before tourniquet inflflation (T0), and at 0.5 h (T1), 2 h (T2), 6 h (T3) after tourniquet deflflation. RESULTS: Compared with baselines at T0, MDA levels signifificantly increased at T2, T3 in the NS group and at T3 in the nebulization group, and IL-6 and IL-8 levels were signifificantly increased at T2, T3 in NS, the intravenous drip and the nebulization groups (P <0.05). Arterial pressure of oxygen (PaO2) at T3 was decreased, while alveolararterial oxygen tension showed difference (PA-aDO2) at T3 in the NS group; RI at T3 in both intravenous drip and the nebulization groups were enhanced (P <0.05). Compared with the NS group, MDA and IL-8 levels at T2, T3, IL-6 at T3 in the intravenous drip group, and IL-8 at T3 in the nebulization group were all remarkably increased (P <0.05). Additionally, MDA level at T3 in the nebulization group was higher than that in the intravenous drip group (P <0.05). CONCLUSIONS: Intravenous administration of Shenmai Injection provided a better protective effect than nebulization in mitigating pulmonary gas exchange dysfunction in patients following tourniquet-induced limb ischemia-reperfusion.

[Nrf2/ARE pathway mediates the reducing effect of Dexmedeto-midine on ischemia/reperfusion injury in skeletal muscle].

OBJECTIVE: To explore the role of Nrf2/ARE pathway in skeletal muscle ischemia/reperfusion(I/R) injury preconditioning by dexmedetomidine(DEX). METHODS: Twenty-eight SD rats were randomly divided into sham-operated(Sham group)、I/R group、I/R+ DEX(DEX group) and I/R+DEX +Atipamezole (Atip group). In the Atip group, Atip(250 µg/kg) and DEX(25 µg/kg) were injected together after anesthesia; In the Sham and I/R groups, the homologous saline was also injected at the same time; In the DEX group, the homologous DEX and saline were coinjected. After 30 minutes, the hind limb ischemia was induced by clamping the common femoral artery and ligaturing collateral circulation. After 3 h of ischemia, the clamp and tourniquet were removed and the rats underwent 2 h of reperfusion. We measured plasma concentrations of lactate dehydrogenase (LDH) and creatine kinase(CK). The gastrocnemius muscle was harvested and immediately stored at -80℃ for the assessment of malondialdehyde(MDA)、superoxide dismutase(SOD) and Nrf2/HO-1 protein detected by Western blot. The other section muscle was stored in triformol for immunohistochemical and HE staining. The wet/dry was also immediately detecting. RESULTS: The levels of wet/dry、MDA、LDH、CK、Nrf2 and HO-1 were higher(P<0.05) while the level of SOD was lower(P<0.05) in the I/R group than those in sham group. The levels of wet/dry、MDA、LDH、CK were significantly lower(P<0.05) yet the levels of SOD and Nrf2/HO-1 were significantly higher(P<0.05) in DEX group than those in I/R group. However, Atip reversed the effect of DEX in Atip group, each of indicators had significant changes compared with those in the DEX group(P<0.05). CONCLUSIONS: Nrf2 protein was expressed in skeletal muscle of rat and DEX could promote its level in nucleus by α-adrenergic receptor. The down-stream products of Nrf2 have the effect of antioxidant.

Dynamics of transfer and distribution of 95Zr in the broadbean-soil ecosystem.

The transfer and distribution of (95)Zr in a simulated broadbean-soil system was studied by using isotope-tracer techniques. The results showed that the (95)Zr was mainly concentrated in the haulm, pod and root, and the activity concentration of (95)Zr in these tissues reached the maximum in the initial stage then decreased continuously. The activity concentration of (95)Zr in edible part-bean was relatively lower, which was just near to the detection limit. The (95)Zr in soil was mainly (97%) deposited in surface layer soil (0-6 cm), indicating that the (95)Zr absorbed by surface soil could not be moved downwards easily because of the strong adsorption. The dynamics of (95)Zr concentrations in broadbean and soil were also confirmed by application of nonlinear regression method.

Effects of COX-2 inhibitor on ventilator-induced lung injury in rats.

BACKGROUND: Mechanical ventilation especially with large tidal volume has been demonstrated to activate inflammatory response inducing lung injury, which could be attenuated by cyclooxygenase (COX)-2 inhibitors. As the main small integral membrane proteins that selectively conduct water molecules' transportation, aquaporin (AQP)-1 downregulation significantly related to lung edema and inflammation. This study aims to investigate the role of AQP1 in ventilator-induced lung injury in rats and evaluates the effects of COX-2 inhibition. METHODS: Forty rats were allocated into four groups, where rats in Groups LD (low volume+DMSO) and LN (low volume+NS-398) were given intravenously 2ml DMSO and 8mg/kg NS-398 (a specific COX-2 inhibitor, dissolved in 2ml DMSO) before 4-hour lower tidal volume ventilation (8ml/kg), respectively, while DMSO and NS-398 were administrated in the same manner before 4-hour injurious ventilation (40ml/kg) in Groups HD (high volume+DMSO) and HN (high volume+NS-398). The arachidonic acid metabolites (6-keto prostaglandin F1α, thromboxane B2), inflammatory cytokines (tumor necrosis factor-α, interleukin-1ß, 6, 8) and total protein levels in bronchoalveolar lavage (BAL) fluid and COX-2 mRNA and AQP1 protein expression in lung tissue were detected; water content and lung morphology were also evaluated. RESULTS: Compared to Groups LD and LN, the rats in Groups HD and HN suffered obvious lung morphological changes with higher wet-to-dry weight ratio and lung injury score, and the levels of arachidonic acid metabolites, inflammatory cytokines and total protein in BAL fluid were increased, the expression of COX-2 mRNA was significantly upregulated and AQP1 protein was downregulated in lung tissue (p<0.05). The changes in BAL fluid and the severity of lung injury were attenuated, and AQP1 expression was upregulated in Group HN as compared to HD (p<0.05). CONCLUSIONS: Ventilation with large tidal volume causes inflammatory mediator production and AQP1 downregulation, which could be attenuated by COX-2 inhibition.

Biosynthesis of benzoylformic acid from benzoyl cyanide by a newly isolated Rhodococcus sp. CCZU10-1 in toluene-water biphasic system.

Benzoylformic acid was synthesized from the hydrolysis of benzoyl cyanide by a newly isolated Rhodococcus sp. CCZU10-1. In this study, an aqueous-toluene biphasic system was developed for highly efficient production of benzoylformic acid from the hydrolysis of benzoyl cyanide. In the aqueous-toluene biphasic system, the phase volume ratio, buffer pH and reaction temperature were optimized. Using fed-batch method, a total of 932 mM benzoylformic acid accumulated in the reaction mixture after the 10th feed. Moreover, enzymatic hydrolysis of benzoyl cyanide using calcium alginate entrapped resting cells was carried out in the aqueous-toluene biphasic system, and efficient biocatalyst recycling was achieved as a result of cell immobilization in calcium alginate, with a product-to-biocatalyst ratio of 14.26g benzoylformic acid g(-1) dry cell weight (DCW) cell after 20 cycles of repeated use.