Objective To analyze the effects of different doses of rapamycin on hepatic ischemia reperfusion injury in rats and the possible mechanism.Methods 48 Sprague-Dawley rats were randomly divided into four groups(n=12),low dose group (preoperative injection of low dose of rapamycin+ischemia),high dose group (preoperative high dose of rapamycin injection + ischemia),model group (preoperative injection of 0.9％ sodium chloride solution + ischemia),sham group (preoperative injection of 0.9％ sodium chloride solution,only dissected the first hepatic portal).Serum was collected 24 and 72 hours after surgery,ALT,AST,TNF-α and IL-6 concentrations were detected,Western blotting and PCR were performed to detect the expression of autophagy proteins,and HE staining was performed.Results 24 h after the operation,the liver tissue of the sham group was almost normal,the hepatic lobule structure of the model group disappeared,the liver cells were edema,vacuolar degeneration and necrosis,and the damage was reduced in the low dose and high dose group.24 h after surgery,levels of ALT,AST,TNF-α and IL-6 was on a declining curve in all groups,with statistically significant differences (P＜0.05).24 h after surgery,the relative expression levels of ULK1 (1.00±0 vs.4.76±2.62 vs.8.26±3.46 vs.12.95±6.45),microtubuleassociated protein 1 light chain 3(LC3,1.00±0 vs.2.88±0.59 vs.4.66± 1.22 vs.7.10±0.85) mRNA in sham group,model group,low dose group and high dose group were increased.While the relative mRNA expression levels of mammalian target of rapamycin (mTOR,1.00±0 vs.0.31 ±0.09 vs.0.18±0.04 vs.0.02± 0.01),P70 ribosomal protein kinase (S6K1,1.00±0 vs.0.57±0.34 vs.0.27±0.14 vs.0.03±0.01) showed a decreasing trend,and the differences were statistically significant (P＜0.05).24 h after surgery,the relative expressions of ULK1 and LC3 proteins in sham group,model group,low dose group and high dose group increased,while the phosphorylation of mTOR,S6K1 and ULK1 decreased,with statistically significant differences (P＜0.05).72 h after the operation,the results were agreed with those at 24 h after the operation.Conclusion Rapamycin activates autophagy through mTORC1-ULK1 signaling pathway to reduce HIRI,and the protective effect of high dose is better than that of low dose.

Objective:To investigate the effect of rapamycin on hepatic ischemia-reperfusion injury (HIRI) in Sprague Dawley (SD) rats and its underlying mechanism.Methods:Forty-eight specific pathogen-free SD male rats with the body weight of 180-200 g and the age of 4-8 weeks were randomly divided into 3 groups, 16 rats each group. In the rapamycin group, the rats were injected with rapamycin intraperitoneally everyday lasting for 3 days before the surgery, and in the model group and the sham group, the rats were injected with normal saline intraperitoneally. The HIRI model was performed in the rapamycin group and the model group. Serum of 8 rats was randomly harvested from each group at 2 h and 24 h after the surgery and was used to detect level of alanine aminotransferase(ALT), total bilirubin, and lactate dehydrogenase. At the meantime, liver tissues were collected for HE staining, and enzyme-linked immunosorbent assay of superoxide dismutase(SOD), glutathione, hexokinase 2, phosphofructokinase 1(PFK1), and adenosine triphosphate. Polymerase chain reaction and Western blots were used to determine the levels of mammalian target of rapamycin(mTOR), ribosomal protein S6 kinase 1(S6K1), and protein kinase B and their phosphorylation levels respectively.Results:Two hours post the surgery, the serum level of ALT(150.9±18.7) U/L, total bilirubin(5.15±0.69) μmol/L, and lactate dehydrogenase(9 547±365) U/L were higher in the model group than sham group (42.4±10.7) U/L, (2.48±0.24) μmol/L, (4 424±376) U/L and rapamycin group (87.7±11.2) U/L, (3.09±0.12) μmol/L, (8 268±264) U/L, and all differences were statistically significant (all P<0.05). HE staining and serum assay showed that the lesion of liver tissuesand of liver function were damaged in the model group, and mitigated in the rapamycin group at 2h and 24h after the surgery. At 2h and 24h after the surgery, liver SOD, glutathione, hexokinase 2, PFK1, and adenosine triphosphate in the model group were lower than those in the sham group and the rapamycin group, and all differences were statistically significant (all P<0.05). The relative levels of mTOR, S6K1, and their phosphorylation level in the model group were higher than those in the sham group and the rapamycin group at 2 h and 24 h after the surgery, but the relative levels of protein kinase B and phosphorylated protein kinase B were lower than those in the sham group and the rapamycin group, and all differences were statistically significant (all P<0.05). Conclusions:Rapamycin improves glucose metabolism and reduces oxidative stress via upregulating the phosphorylated protein kinase B through inhibition of mTOR signaling pathway, thus alleviates HIRI in rats.

Objective: To explore the clinical effects and key techniques of expanded super-thin perforator flaps in the shoulder, neck, and chest in reconstruction of extensive burn scars in the face. Methods: From January 2008 to November 2018, 22 patients with extensive burn scars in the face were admitted to the Department of Plastic Surgery of Dongguan Kanghua Hospital and the Department of Plastic Surgery of Dermatology Hospital of Southern Medical University, with 3 males and 19 females, aged from 4 to 48 years. There were 16 cases of type Ⅱ and 6 cases of type Ⅲ in facial scars. Before the first stage of expansion surgery, Doppler blood flow survey meter or multi-slice CT was used to locate the perforator vessels. One to four expanders with rated capacity ranged from 100 to 600 mL were placed in the patients. We gave 20% to 30% of the rated capacity of expander intro-operation and common injection with 10% to 15% of the rated capacity of expander per week post-operation until the volume reached 1.5 to 2.5 times of the rated capacity of expander during the past 3 to 4 months. At the second stage of surgery, the perforators were located again before surgery with the same method. The size of defects after the excision of facial scars ranged from 6 cm×4 cm to 18 cm×16 cm. With perforators used as nutrient vessels, narrow pedicle flaps or random flaps ranging from 6 cm×6 cm to 22 cm×18 cm were elevated as rotating or advancing to reconstruct the defects. The donor sites were sutured directly. Some of the flaps needed stage Ⅲ operation for cutting the pedicle. The survival of flaps, post-operation complications, and follow-up were assessed. Results: All flaps of 22 patients survived. All the donor sites were closed simultaneously. One patient underwent an additional surgery for 5 cm×4 cm necrosis on distal part of flap caused by subcutaneous hematoma. Two patients with epidermis blister on the flaps were healed by themselves after dressing change. Due to rapid expansion, blood capillary proliferation appeared on the central part of the flap in 3 cases, after slowing down the expansion speed properly, which had no impact on flap transfer. No ischemia or venous congestion phenomenon were observed in the other flaps. During follow-up of 5 to 48 months, the flaps of patients showed no significant bloated appearance, with good complexion and texture, and even could reproduce facial fine-grained expressions naturally. Conclusions For the reconstruction of extensive burn scars in the face, expanded super-thin perforator flaps can not only acquire large and thin flaps with high matching degree surface skin defect, but also reproduce facial fine-grained expressions. It is a simple and safe method which conforms to the facial aesthetic standard.