To observe the pathologic changes of normal tissue in nude mice after peritoneal perfusion with hyperthermia, hyper-osmolar solution and mitomycin C (MMC). Fifty BALB/c nunu mices (7-10 weeks old) bearing HT-2 lines were chosen for the study, and were randomly divided into five groups: isotonic solution (control group), hyperosmolar solution (HOS group), HOS plus MMC group, hyperthermia (HT group) and HOS plus HT plus MMC group. After continuous hyperthermic peritoneal perfusion (42℃/30min) with 7.5% NaCl and 5μg/ml MMC, the liver, spleen, small intestine and kidney were examined by light microscopy. Results: ①In HOS and HOS plus MMC groups, no changes of liver, spleen and kidney were found. ②In HT and HOS plus HT plus MMC groups, slight degeneration of liver, hyperemia of spleen, swelling of kidney tubule cells and small intestine were found. ③In HOS plus HT plus MMC group, partial loss of small intestinal villi were also observed. Conclusioin: After continuous hyperthermic perfusion conbined with hyper-osmolar solutions and mitomycin C, a slight injury was showed in normal tissue of nude mice.
ObjectiveTo evaluate the safety of arthroscopic operation with artificial space on the buttocks for gluteal muscles contracture (GMC) by measuring the plasma osmolarity. MethodsBetween May and June 2011, 30 cases of GMC were joined in the study. Of them, 11 were male and 19 were female with an age range from 4 to 39 years (mean, 24.4 years). Twenty-eight patients had a definite history of repeat intragluteal injection. The disease duration ranged from 1-30 years (mean, 14 years). During operation, normal saline solution was used as lavage fluid, and radiofrequency energy was used as cutter for releasing GMC. The plasma sodium, plasma potassium, blood glucose, blood urea nitrogen concentrations, and plasma osmolarity were compared before and after operation; input and output volume of lavage fluid and intravenous dropping volume were recorded. Whether patients suffered from water intoxication or not was observed. The effect was evaluated through the criteria proposed by XIA Rongxi et al. ResultsThe operation was successfully completed in all patients, who had no water intoxication. The operation time was 16-70 minutes (mean, 33.4 minutes). The input volume was 2-23 L (mean, 6.3 L), the output volume was 2-22 L (mean, 5.8 L), and the absorption volume was 0.1-1.2 L (mean, 0.5 L); and the intravenous dropping volume was 350-1 300 mL (mean, 850 mL). No significant difference was found in plasma sodium, plasma potassium, blood glucose, blood urea nitrogen concentrations, and plasma osmolarity between before and after operations (P>0.05). All patients were followed up 3-26 months (mean, 12.7 months). At last follow-up, according to XIA Rongxi's et al evaluation standard, the results were excellent in 27 cases, good in 3 cases, and the excellent and good rate was 100%. ConclusionArthroscopic operation with artificial space on the buttocks is safe and reliable in the treatment of GMC.
As a representative part of the oral system and masticatory robot system, the modeling method of the dental model is an important factor influencing the accuracy of the multi-body dynamic model. Taking the right first molars of the masticatory robot as the research object, an equivalent model, point-contact higher kinematic pair composed of v-shaped surface and sphere surface, was proposed. Firstly, the finite element method was used to analyze the occlusal dynamics of the original model in three static contact cases (intrusive contact, centric occlusion, and extrusive contact) and one dynamic chewing case, and the expected bite force was obtained. Secondly, the Hertz contact model was adopted to establish the analytical expression of the bite force of the equivalent model in three static contact cases. The normal vectors and contact stiffness in the expression were designed according to the expected bite force. Finally, the bite force performance of the equivalent model in three static contact cases and one dynamic chewing case was evaluated. The results showed that the equivalent model could achieve the equivalent bite force of 8 expected items in the static contact cases. Meanwhile, the bite force in the early and late stages of the dynamic chewing case coincides well with the original model. In the middle stage, a certain degree of impact is introduced, but it can be weakened by subsequent trajectory planning. The equivalent modeling scheme of the dental model proposed in this paper further improves the accuracy of the dynamic model of the multi-body system. It provides a new idea for the dynamic modeling of other complex human contacts.
Stress distribution of denture is an important criterion to evaluate the reasonableness of technological parameters, and the bite force derived from the antagonist is the critical load condition for the calculation of stress distribution. In order to improve the accuracy of stress distribution as much as possible, all-ceramic crown of the mandibular first molar with centric occlusion was taken as the research object, and a bite force loading method reflecting the actual occlusal situation was adopted. Firstly, raster scanning and three dimensional reconstruction of the occlusal surface of molars in the standard dental model were carried out. Meanwhile, the surface modeling of the bonding surface was carried out according to the preparation process. Secondly, the parametric occlusal analysis program was developed with the help of OFA function library, and the genetic algorithm was used to optimize the mandibular centric position. Finally, both the optimized case of the mesh model based on the results of occlusal optimization and the referenced case according to the cusp-fossa contact characteristics were designed. The stress distribution was analyzed and compared by using Abaqus software. The results showed that the genetic algorithm was suitable for solving the occlusal optimization problem. Compared with the reference case, the optimized case had smaller maximum stress and more uniform stress distribution characteristics. The proposed method further improves the stress accuracy of the prosthesis in the finite element model. Also, it provides a new idea for stress analysis of other joints in human body.