2006年 · 第09卷第05期

Abstract：Objective: To observe the morphological characteristics of sacral fracture under different impact loads.Method: Ten fresh pelvic specimens were loaded in dynamic or static state. A series of mechanical parameters including the pressure strain and velocity were recorded.Morphological characteristics were observed under scanning electron microscope.Results: The form of sacral fracture was related to the impact energy. Under low-energy impact loads, ilium fracture, acetabulum fracture and crista iliaca fracture were found. Under high-energy impact loads, three types of sacral fracture occurred according to the classification of Denis: sacral ala fracture, Type Ⅰ fracture; sacral foramen cataclasm fracture, Type Ⅱ fracture; central vertebral canal fracture, Type Ⅲ fracture. Nerve injury of one or two sides was involved in all three types of sacral fracture.The fracture mechanism of sacrum between the dynamic impact and static compression was significantly different.When the impact energy was above 25 J, sacral foramen cataclasm fracture occurred, involving nerve root injury.When it was below 20 J, ilium and sacral fracture was most likely to occur. When it was 20 ～ 25 J, Type Ⅰ fracture would occur. While in the static test, most of the fracture belonged to ilium or acetabulum fracture. The cross section of sacrum was crackly and the bone board of Haversian system was brittle, which could lead to separation of bone boards and malposition of a few of cross bone boards.Conclusions: In dynamic state, sacrum fracture mostly belongs to Type Ⅰ and Type Ⅱ, and usually involves the nerve roots. Sacrum fracture is relevant to the microstructures, the distribution of the bone trabecula, the osseous lacuna and the Haversian system of sacrum. The fracture of ilium and acetabulum more frequently appears in static state, with slight wound of peripheral tissues。

Abstract：Objective: To investigate the effect of cancellous bone matrix gelatin (BMG) engineered with allogeneic chondrocytes in repairing articular cartilage defects in rabbits.Methods: Chondrocytes were seeded onto three-dimensional cancellous BMG and cultured in vitro for 12 days to prepare BMG-chondrocyte complexes. Under anesthesia with 2.5% pentobarbital sodium (1 ml/kg body weight), articular cartilage defects were made on the right knee joints of 38 healthy New Zealand white rabbits (regardless of sex, aged 4-5 months and weighing 2.5-3 kg) and the defects were then treated with 2.5 % trypsin.Then BMG-chondrocyte complex (Group A, n=18 ),BMG ( Group B, n=10), and nothing ( Group C, n=10)were implanted into the cartilage defects, respectively. The repairing effects were assessed by macroscopic, histologic,transmission electron microscopic (TEM) observation,immunohistochemical examination and in situ hybridization detection, respectively, at 2, 4, 8, 12 and 24 weeks after operation.Results: Cancellous BMG was degraded within 8 weeks after operation. In Group A, lymphocyte infiltration was observed around the graft. At 24 weeks after operation, the cartilage defects were repaired by cartilage tissues and the articular cartilage and subchondral bone were soundly healed. Proteoglycan and type Ⅱ collagen were detected in the matrix of the repaired tissues by Safranin-O staining and immunohistochemical staining,respectively. In situ hybridization proved gene expression of type Ⅱ collagen in the cytoplasm of chondrocytes in the repaired tissues. TEM observation showed that chondrocytes and cartilage matrix in repaired tissues were almost same as those in the normal articular cartilage. In Group B, the defects were repaired by cartilage-fibrous tissues. In Group C, the defects were repaired only by fibrous tissues.Conclusions : Cancellous BMG can be regarded as the natural cell scaffolds for cartilage tissue engineering.Articular cartilage defects can be repaired by cancellous BMG engineered with allogeneic chondrocytes. The nature of repaired tissues is closest to the normal cartilage. Local administration of trypsin can promote the adherence of repaired tissues to host tissues. Transplantation of allogeneic chondrocytes has immunogenicity, but the immune reaction is weak。

Abstract：Objective: To avoid disadvantages of two-stage cancellus bone autograft, we investigated the feasibility of one-stage allograft for reconstructing the bone defect resulting from debridement of chronic osteomyelitis in limbs.Methods: Between Feb. 1999 and Apr. 2004, 35 cases of chronic osteomyelitis (8 cases of nonunion )underwent one-stage allograft after debridement in our hospital.Results: Thirty-five cases were followed up for an average period of 28 months (range, 13 to 55 months), in which 32 cases (91.43%) were found no infection, and 3cases (8.57 %) were confirmed recurrence of infection.Four out of 8 cases of bone nonunion healed in 9.5 months on average (range, 3 to 12 months), and another case also acquired union after redebridement and autograft of ilium due to infection recurrence 35 days after surgery.Renonunion occurred in 3 cases, 2 out of whom healed after secondary operation with autograft. One case of renonunion and 2 cases of infection recurrence refused further treatment.Conclusions: A high rate of infection arrest can be attained when one-stage allograft is used to reconstruct the bone defect of chronic osteomyelitis after debridement in limbs. Therefore, chronic osteomyelitis should not be regarded as a contraindication to one-stage allogeneic bone grafting. Renonuion, however, achieves a relatively high rate, especially in cases of segmental bone defect。

Abstract：Objective: To investigate the therapeutic effect of Bcl- 2 fusion protein on apoptosis in brain following traumatic brain injury.Methods: Bcl-2 gene was cloned by RT-PCR. Bcl-2 and EGFP genes were linked together and inserted into pAdeno-X vector. This recombinant vector was packaged into infectious adenovirus in HEK293 cells. Ninety Wistar rats were assigned randomly into experimental group(n=45) and control group (n=45). All rats were subjected to traumatic brain injury. Then recombinant adenovirus (for experimental group) or saline (for control group) was injected into the traumatic brain. The expression of Bcl-2 fusion protein was investigated by Western blotting, immunohistochemistry and fluorescence microscopy. Apoptosis in the injured brain was studied by TUNEL. Animals' behavior capacity was evaluated by tiltboard test.Results: In the experimental group, many fluorescent cells were found around the traumatic locus,which were also proven to be Bcl-2-positive by immunohistochemistry. On the contrary, few Bcl-2-positive cells and no fluorescent cell were detected in the control group. Bcl-2 expression of experimental group was much higher than that of control group, which was illustrated by Western blotting. The apoptosis index of experimental group was 0.027 ± 0.005, and that of control group was 0.141±0.025 (P＜0.01). Two weeks after injury, animals of the experimental group behaved better than those of the control group.Conclusions: A recombinant adenovirus vector expressing Bcl-2 fusion protein has been constructed. Bcl-2 fusion protein can suppress apoptosis and promote cell survival. Moreover, the behavior recovery of the injured animal is promoted. Bcl-2 fusion protein provides a way to track the target cells in vivo。

Abstract：Objective: To evaluate the therapeutic effects and complications of hydroxyapatite (HA) orbital implantation on patients after trauma-related surgeries.Methods: Retrospective analysis was made from 211 cases (211 eyes ) who underwent HA orbital implant placement after trauma-related enucleation or evisceration,including 68 cases of evisceration and primary HA implant placement, 77 cases of enucleation and HA implant placement wrapped with multi-windowed sclera, 66 cases of enucleation and HA implant placement free of wrapping.All the cases were followed up for 1-5 years to observe the therapeutic effects and major complications.Results: Five of 211 cases had wound dehiscence.Ten cases had HA implants exposure, including 1 case suffering severe orbital infection and requiring HA implant removal. The implants exposure incidences by the three surgical methods were from 1.30% to 10.06% and averaged 4.74%. Significant difference was found in late exposure incidence and total incidence from the three methods ( χ2 = 13.372, P ＜ 0.01 and χ2 = 7.540, P ＜ 0.05).Two cases had shrinkage of the lower fornix. Enophthalmos occurred in 1 case treated by method 1 and was corrected by implanting porous polyethylene (Medpor) plate into the bottom of orbit. In 210 cases, the artificial eye moved well and the cosmetic results were satisfactory.Conclusions: Different surgical methods have their own merit and disadvantage. Enucleation and placement of HA implant wrapped with multi-windowed sclera has corroborated fewer complications than others。

Abstract：Objective: To evaluate the biomechanical effect and clinical results of hook screw fixation after direct repair of lumbar spondylous defects in the pars interarticularis.Methods: L2-L6 spines of 8 fresh-frozen and thawed calf cadavers were used for mechanical testing. Bilateral spondylous defects were created in the L4 vertebra. The intervertebral rotation ranges between L4 and Ls were scanned and computerized in various states of motion, such as flexion/extension, lateral bending and torsional loadings applied on the intact spine and the spondylous spine when the spondylous spine was fixed with modified Scott's fixation, hook screw fixation and Buck's fixation sequentially and respectively. Between July 2002 and February 2004, 14 young male patients (aged 15-31 years)suffering from symptomatic lumbar spondylolysis were treated with TSRH hook screw fixation after direct repair of the defects. MacNab criteria1 were used to assess their preand post-operative status.Results: Each fixation technique could significantly increase the intervertebral rotational stiffness and made the stiffness return to nearly the intact level. Hook screw technique provided more rotational stability than the others. Hook screw and Buck's techniques provided more flexion/extension stability than modified Scott's technique.Neither complication nor instrumental failure was observed in this study. The mean follow-up period was 21 months.All the patients except one acquired union during the follow-up period. Thirteen patients had a "good" or "excellent" result according to MacNab criteria.Conclusions: Hook screw fixation shows biomechanical advantages and is safe and effective for young patients with lumbar spondylolysis。

Abstract：Objective: To investigate the detrimental effects of hemorrhagic shock on the structure and function of mitochondria DNA (mtDNA) encoding cytochrome oxidase genes in intestinal epithelial cells.Methods: Wistar rats were used and divided into two groups: hemorrhagic shock group and control group.Hemorrhagic shock model of rats was utilized in this experiment. The mtDNA was extracted from the intestinal epithelial cells and amplified by polymerase chain reaction (PCR) with different primers of cytochrome oxidase (COX Ⅰ, COX Ⅱ and COX Ⅲ ). The products of PCR were directly sequenced.Results: Hemorrhagic shock could result in the point mutagenesis in mitochondrial genome encoding cytochrome oxidase ( COX Ⅰ and COX Ⅱ). There were 4, 4, 22, 16, 35 point mutations in COX Ⅰ from 5545 to 6838 bp in 5shocked rats. There were five point mutations in COX Ⅱ from 7191 to 7542 bp at the site of t7191c, t7212c, a7386g,a7483g, c7542g in 1 shocked rat. There was no mutation found in COX Ⅲ.Conclusions: Hemorrhagic shock could significantly induce the damage of the gene of cytochrome oxidase encoded by mtDNA。

Abstract：Objective: To evaluate the effects of repairing rabbit radial defects with polyester/tricalcium phosphate scaffolds prepared by rapid prototyping technology loaded with bovine bone morphogenetic protein (bBMP), and find new carriers for growth factors.Methods: Polyester/tricalcium phosphate scaffolds prepared by rapid prototyping technology loaded with and without bovine BMP were used to repair the 15 mm radial defect in rabbit. Then the results of radiography,histology, scaffolds degrade rates and bone mineral density(BMD) were appraised to examine the effects at the 12th week.Results: At the 12th week postoperatively, all defects treated with bBMP were radiographically repaired. No radius implanted polyester/tricalcium phosphate scaffolds without bBMP showed radiographic and histological union.At experimental groups, longitudinal alignment of lamellar structure was observed histologically at the 12th week,indicating that remodeling of regenerated bone was complete in different degree. Of the three experimental groups, the bony regeneration and remodeling of callus in poly lactide-co-glycolide/tricalcium phosphate (PLGA/TCP) group was the best. The BMD values were beyond 70% of normal value at the 12th week while the PLGA/TCP scaffolds group was the highest, and no abnormalities were observed in the surrounding soft tissue in all groups.Conclusions : Polyester/tricalciumphosphatescaffolds prepared by rapid prototyping technology loaded with bovine BMP can repair a 15 mm radial defect of rabbit. As for the results, the PLGA/TCP scaffold is ideal and better than poly L-lactide-co-D, L-lactide (PDLLA/TCP)scaffold, but the ploy L-lactic acid (PLLA/TCP) is not so good for its low degradation rates。

Abstract：Objective: To observe the effect of quercetin on experimental spinal cord injury (SCI) in rats.Methods: Sixty Sprague-Dawley rats were randomly divided into four groups: Group A only for laminectomy,Group B for laminectomy with SCI, Group C for SCI and intraperitoneal injection with a bolus of 200 mg/kg quercetin and Group D for SCI and intraperitoneal injection of saline. SCI model was made by using modified Allen's method on T12. Six rats of each group were killed at4 h after injury and the levels of free iron and malondialdehyde (MDA) of the involved spinal cord segments were measured by bleomycin and thiobarbituric acid (TBA) assays separately. The recovery of hind limb function was assessed by Modified Tarlov's scale and inclined plane method at 7 d,14 d and 21 d after SCI. The histological changes of the damaged spinal cord were also examined at 7 d after SCI.Results: After SCI, the levels of free iron and MDA were significantly increased in Groups B and D, while not in Group C. The Modified Tarlov's score and the inclined plane angles were significantly decreased in Groups B, C and D. The histological findings were not improved.Conclusions: After SCI, quercetin can reduce the level of lipid peroxidation, but not improve recovery of function。

Abstract：Differentiation, the stepwise specialization of cells, and transdifferentiation, the apparent switching of one cell type into another, capture much of the stem cell spotlight. But dedifferentiation, the developmental reversal of a cell before it reinvents itself, is an important process too. In multicellular organisms, cellular dedifferentiation is the major process underlying totipotency, regeneration and formation of new stem cell lineages. In humans,dedifferentiation is often associated with carcinogenesis.The study of cellular dedifferentiation in animals,particularly early events related to cell fate-switch and determination, is limited by the lack of a suitable,convenient experimental system. The classic example of dedifferentiation is limb and tail regeneration in urodele amphibians, such as salamanders. Recently, several investigators have shown that certain mammalian cell types can be induced to dedifferentiate to progenitor cells when stimulated with the appropriate signals or materials. These discoveries open the possibility that researchers might enhance the endogenous regenerative capacity of mammals by inducing cellular dedifferentiation in vivo。

Abstract：The concepts of systemic inflammatory response syndrome (SIRS) and scoring system were defined by the journal of Bone in 1992. SIRS was described as occurrence of two or more clinical criteria in four ones (fever or hypothermia, tachypnea, tachycardia, and leukocytosis).An early diagnosis and estimation of systemic inflammation in patients is helpful for treatment selection. This paper reviews the application of SIRS scoring system, which has been extensively validated for large groups of critical care patients with severe injury and critical surgical diseases.Recent studies have documented SIRS score as a significant predictive parameter of adverse outcome in critical care patients. Furthermore, some studies also give us a suggestion on how to reduce the overload systemic response。