[Finite element optimization analysis of minimally invasive screw treatment for Sanders typeâ ¡calcaneal fracture].

OBJECTIVE: To explore biomechanical characteristics of minimally invasive different screw fixations in treating Sanders typeⅡcalcaneal fractures. METHODS: Dicom data of calcaneus by CT scan were input into Mimics 21.0 software and Ansys15.0 software to construct three-dimensional finite element digital model of calcaneus;this model was input into UG NX 10.0 software, and calcaneus was cut according to Sanders classification to establish Sanders typeⅡ calcaneus model with posterior articular surface collapse;then simulated minimally invasive screw internal fixation after calcaneal fracture:a screw from posterior articular surface was used to outside-in fix sustentaculum tali, other 4 screws were used to fix calcaneus by different methods through calcaneal tuberosity, and 4 different calcaneal models were obtained. Under the same conditions, 4 types of internal fixation models were loaded respectively, and nonlinear finite element analysis was performed to calculate the stress distribution of different internal fixation models. RESULTS: Under the same condition of loading, the model 3 had smaller displacement value, maximum calcaneus displacement value and maximum equivalent stress value of the screw than other three internal fixation models, and the stress was more dispersed. CONCLUSION: In minimally invasive screw internal fixation of calcaneus fracture, after 1 sustentaculum tali screw fixation, 2 screws crossed fix posterior articular surface from calcaneal tuberosity, 2 screws fix parallelly calcaneocuboid joint from calcaneal tuberosity are more suitable for biomechanical requirements, and could provide basic theory for clinical treatment.

Knockout of E2F1 enhances the polarization of M2 phenotype macrophages to accelerate the wound healing process.

Wound healing is a complex process, which is classically divided into inflammation, proliferation, and remodeling phases. Macrophages play a key role in wound healing, however, whether E2F1 mediates the M1/M2 polarization during the wound healing process is not known. Skin wounds were surgically induced in E2F1-/- mice and their WT littermates. At day 2 and day 7 post-surgery, the wounded skin tissues including 2 to 3 mm normal skin were obtained. The wounded skin tissues were used for the analyses of immunofluorescence staining (CD68, iNOS, CD206), western blotting (CD68, iNOS, CD206, PPAR-γ) and Co-immunoprecipitation (E2F1-PPAR-γ interactions). E2F1-/- mice exhibited faster wound healing process. At day 2, the M2 macrophages were remarkably increased in the E2F1-/- mice. Surprisingly, in the border zone of the wound, E2F1-/- mice had also more M2 macrophages and fewer M1 macrophages at day 7 post-surgery, suggesting a certain degree of polarization amongst the M1 and M2 phenotypes. Co-IP revealed that E2F1 indeed interacted with PPAR-γ, meanwhile western blotting and RT-PCR showed higher expression of PPAR-γ in the E2F1-/- mice as compared to that in the WT mice. Therefore, the findings suggest that wound healing process could be accelerated with enhanced M2 polarization through increased PPAR-γ expression in E2F1 knockout mice.

The biomechanical study of rupture of Achilles Tendon and repair by different suture techniques.

OBJECTIVE: To study the biomechanical properties of different suture methods, and to provide evidence for the clinical application of this suture methods in repairing acute Achilles tendon rupture. METHODS: Twenty four fresh frozen cadaver Achilles tendon specimens were collected and randomly divided into three groups (n=8), Group-A Bunnell suture method, Group-B Bosworth suture and Group-C anchor suture respectively. 5 N tensions were applied to tighten the tendon. The actual length of the tendon between the upper and lower clips was measured with a ruler. The length of the long axis and the short axis of the three sections of the tendon was measured by vernier caliper. The cross sectional area of the tendon was calculated according to the elliptical area formula and the mean value was obtained. RESULTS: There was no significant difference in the length and cross-sectional area of each tendon among three groups (F=0.26, P=0.86; F=0.09, P=0.96). There was no significant difference in the maximum load of tendon and failure displacement in Group A and B (P>0.05). The maximal load of Group-C was significantly larger than that of Group A and B (P<0.05), and there was no significant difference between the failure displacement and Group A and B (P>0.05). CONCLUSION: Three suture methods can provide good biomechanical properties, but the anchor suture is more effective in solving the shortcomings of traditional methods. It is a safe and effective method, and is worthy of promotion.

Alteration of NPY in hypothalamus and its correlation with leptin and ghrelin during the development of T2DM in a rat model.

OBJECTIVES: This study aimed to investigate the alteration of Neuropeptide Y (NPY) in the hypothalamus and its correlation with insulin, leptin and ghrelin during the development of a rat model of type 2 diabetes mellitus. METHODS: The type 2 diabetes mellitus model was developed in diet-induced obesity (DIO) rats followed by the intraperitoneal injection of low-dose streptozotocin (STZ, 25 mg/kg). At four time points during the development of type 2 diabetes mellitus in rats, the fasting serum insulin, leptin, and plasma ghrelin were measured and the hypothalamic neuropeptide Y (NPY) content and mRNA expression were detected in the rats, which were divided into 4 groups: normal control (NC), DIO4W, DIO8W, and T2DM; the mRNA expression of OB-Rb, and GSH-R1a in the hypothalamus were also assayed. RESULTS: During the development of the type 2 diabetes mellitus rat model, both the fasting serum levels of insulin and leptin (ng/ml) elevated significantly and the fasting plasma ghrelin concentration decreased the hypothalamic NPY (pg/mg) content significantly. NPY mRNA increased significantly in a time-dependent fashion while both the OB-Rb and the GHS-R1a mRNA of the hypothalamus decreased significantly. Hypothalamic NPY concentration was positively correlated with the changes in serum insulin and leptin and negatively correlated with plasma ghrelin. CONCLUSIONS: During the development of the type 2 diabetes mellitus rat model, the hypothalamic NPY content and NPY mRNA expression increased in a time-dependent manner, which was positively correlated with the changes of the serum insulin and leptin and negatively correlated with the plasma ghrelin.

Effect of Nitric Oxide on the Antifungal Activity of Oxidative Stress and Azoles Against Candida albicans.

Nitric oxide (NO) is a small molecule with a wide range of biological activities in mammalian and bacteria. However, the role of NO in fungi, especially Candida albicans, is not clear. In this study, we confirmed the generation of endogenous NO in C. albicans, and found that the production of endogenous NO in C. albicans was associated with nitric oxide synthase pathway. Our results further indicated that the production of endogenous NO in C. albicans was reduced under oxidative stress such as menadione or H2O2 treatment. Meanwhile, exogenous NO donor, sodium nitroprusside (SNP), synergized with H2O2 against C. albicans. Interestingly, SNP could inhibit the antifungal effect of azoles against C. albicans in vitro, suggesting that NO might be involved in the resistance of C. albicans to antifungals. Collectively, this study demonstrated the production of endogenous NO in C. albicans, and indicated that NO may play an important role in the response of C. albicans to oxidative stress and azoles.

Functional outcome of tarsometatarsal joint fracture dislocation managed according to Myerson classification.

Objective : To summarize the functional outcome of tarsometatarsal joint fracture-dislocation managed according to Myerson classification. Methods : Total eighty cases of tarsometatarsal joint fracture-dislocation were treated from Mar 2004 to Feb 2012. According to the Myerson classification, there were 14 cases in type A, 12 cases in type B1, 28 cases in type B2, 11 cases in type C1 and 15 cases in type C2. All the cases were treated with open reduction and internal fixation and the incisions and implants were also selected according to the Myerson classification. X-ray was examined during the follow-up period and functional evaluation was carried out by American Orthopaedic Foot and Ankle Society (AOFAS) midfoot score system. Analysis of variance was used to test the different types of Myerson classification. Results : Sixty eight patients got a mean follow-up of 24 months (15-36 months). No patient suffered from infection, skin flap necrosis and X-ray showed there were no implants loosening or breakage. The mean AOFAS score was 88.4(47-100) and excellent and good result was 89.7%. The differences among Myerson classifications showed that there were statistical significance between type B and type A, type C (P<0.05) Three patients suffered from severe pain and difficult walking, X-ray showed the ambiguity of the joint space, which can be diagnosed as posttraumatic arthritis. One patient had arthrodesis finally. Conclusion : The Myerson classification is helpful to make preoperative plan and judging prognosis to the tarsometatarsal joint injuries. In type B, single or double incisions with screw or plate fixation is enough, while in type A and type C, double or triple incisions with screw or plate fixation in medial joints and Kirschner wire fixation in lateral joints are needed. Postoperatively, the type B patients had better prognosis than type A and type C patients. However, the concomitant injuries around the tarsometatarsal joint were not included in Myerson classification, which is the limitation but cannot be neglected.

Postoperative complications after closed calcaneus fracture treated by open reduction and internal fixation: a review.

OBJECTIVE: To review postoperative complications reported after closed calcaneus fracture treated by open reduction and internal fixation (ORIF). METHODS: Postoperative complications reported in the literature between 1995 and 2012 were identified. Papers were retrieved from publicly available databases and included in this study if they met the following criteria: clinical research of cases of closed calcaneus fracture treated by ORIF; ≥10 cases; detailed information about complications, treatment and follow up. RESULTS: Twenty-one clinical reports were analysed (2046 cases). Reported complications (and incidence rates) were: infection and skin flap necrosis (13.6%); neurovascular injury (2.8%); post-traumatic arthritis (1.2%); malreduction/implant problems (0.8%); nonunion (0.1%). CONCLUSIONS: Postoperative complications after closed calcaneus fracture are common clinical problems that cannot always be avoided. They can even be life altering, due to the requirement for long-term treatment or amputation and their economic impact on the patient. Complications should be diagnosed and treated promptly, to achieve satisfactory outcomes. Nonsurgical treatment (e.g. local wound care, drugs or physical therapy) can be attempted. If such measures fail, surgical treatment (e.g. debridement, skin flap transplantation, implant removal, re-opening of the reduction and internal fixation or subtalar joint arthrodesis) should be considered.

Dynamic expression of extracellular signal-regulated kinase in rat liver tissue during hepatic fibrogenesis.

AIM: To investigate whether extracellular signal-regulated kinase 1 (ERK(1)) is activated and associated with hepatic stellate cell (HSC) proliferation in fibrotic rat liver tissue. METHODS: Rat hepatic fibrosis was induced by bile duct ligation (BDL). Histopathological changes were evaluated by hematoxylin and eosin staining, and Masson's trichrome method. ERK(1) mRNA in rat liver tissue was determined by reverse transcription-polymerase chain reaction, while the distribution of ERK(1) was assessed by immunohistochemistry. ERK(1) protein was detected by Western blotting analysis. The number of activated HSCs was quantified after alpha smooth muscle actin (alpha-SMA) staining. RESULTS: With the development of hepatic fibrosis, the positive staining cells of alpha-SMA increased obviously, and mainly resided in the portal ducts. Fiber septa and perisinuses were accompanied with proliferating bile ducts. The positive staining areas of the rat livers in model groups 1-4 wk after ligation of common bile duct (12.88% +/- 2.63%, 22.65% +/- 2.16%, 27.45% +/- 1.86%, 35.25% +/- 2.34%, respectively) were significantly larger than those in the control group (5.88% +/- 1.46%, P < 0.01). With the development of hepatic fibrosis, the positive cells of ERK(1) increased a lot, and were mainly distributed in portal ducts, fiber septa around the bile ducts, vascular endothelial cells and perisinusoidal cells. Western blotting analysis displayed that the expression of ERK(1) and ERK(2) protein was up-regulated during the model course, and its level was the highest 4 wk after operation, being 3.9-fold and 7.2-fold higher in fibrotic rat liver than in controls. ERK(1) mRNA was expressed in normal rat livers as well, which was up-regulated two days after BDL and reached the highest 4 wk after BDL. The expression of ERK(1) was positively correlated with alpha-SMA expression (r = 0.958, P < 0.05). CONCLUSION: The expression of ERK(1) protein and mRNA is greatly increased in fibrotic rat liver tissues, which may play a key role in HSC proliferation and hepatic fibrogenesis.

Relationship between focal adhesion kinase and hepatic stellate cell proliferation during rat hepatic fibrogenesis.

AIM: To investigate the dynamic expression of focal adhesion kinase (FAK) protein and FAK mRNA in fibrotic rat liver tissue, and the relationship between FAK and hepatic stellate cell (HSC) proliferation. METHODS: Rat hepatic fibrosis was induced by bile duct ligation (BDL). Histopathological changes were evaluated by hematoxylin and eosin staining, and by Masson's trichrome method. FAK mRNA in the rat livers was determined by reverse transcription-polymerase chain reaction (RT-PCR), and the distributions of FAK were assessed immunohistochemistrically. The number of activated HSCs was quantified after alpha smooth muscle actin (alpha-SMA) staining. RESULTS: With the development of hepatic fibrosis, the positively stained cells of alpha-SMA increased obviously, which were mainly resided in the portal ducts, fiber septa and perisinuses accompanied with proliferating bile ducts. The positively stained areas of the rat livers in model groups 1 to 4 wk after ligation of common bile duct (12.88+/-2.63%, 22.65+/-2.16%, 27.45+/-1.86%, 35.25+/-2.34%, respectively) were significantly larger than those in the control group (5.88+/-1.46%) (P<0.01). The positive staining for FAK significantly increased, which was mainly situated in portal ducts, fiber septa and around the bile ducts, vascular endothelial cells and perisinusoidal cells. The expression of FAK was positively correlated with alpha-SMA expression (r = 0.963, P<0.05). FAK mRNA expression was obviously up-regulated in the model groups compared to the control group. CONCLUSION: These data suggest that expressions of FAK protein and mRNA are greatly increased in fibrotic rat livers, which may play an important role in HSC proliferation and hepatic fibrogenesis.