Zheng Qi-xin

Artificial bone of porous tricalcium phosphate ceramics and its preliminary clinical application

SummaryThe authors have prepared the artificial bone of porous tricalcium phosphate ceramics according to an appropriate formula and manufacturing technology. Physical and chemical testing shows that it possesses several distinguishing features: the communicating pores and macro/micropores; mean pore size, 380 μm (from 240 μm to 510 μm); porosity, 46.4 %; and compressive strength, 97.4 kg/cm2. It consists of CaO (49.09 %) and P2O5 (48.84 %). The testing of its biocompatibility shows that it is devoid of systemic or local toxicity, and free of irritation or foreign body response in tissues, and it does not result in hemolysis or mutation. The new bone readily grows into its pores with direct contact to the implanted material. 11 cases of bone defects were treated with this artificial bone with satisfactory results.

Biodegradation of tricalcium phosphate ceramics by osteoclasts

SummaryBiodegradation of tricalcium phosphate (TCP) ceramics was observed through mixed culture of osteoclasts and TCP discsin vitro in this study. Osteoclasts were isolated from newborn SD rat’s marrow of long bone and cultured on TCP discs. The culture terminated at the 48th h and 96th h respectively. Under an inverted microscope, the osteoclasts imparted round or oval body with multinuclear and many thin processes. These cells were positively stained for tartrate-resistance acid phosphatase (TRAP). Scanning electron microscope showed that many resorption lacunae on TCP disc surface and their diameters were smaller than 20 μm. Osteoclasts were located in the lacunae. At the 96th h, the resorption lacunae become larger and osteoclasts showed degeneration. It is suggested that osteoclasts possess ability to re-absorb TCP ceramics underin vitro culturing condition.

Studies on the ossification of compound transplantation of porous tcp ceramics and bone marrow

SummaryFollowing the culture of human red marrow with porous TCP ceramicsin vitro, a large amount culturing marrow cells adhered well to the surface and inner wall of TCP ceramics and spread well over the dish bottom 4 weeks after cultivation. After the compound transplantation of porous TCP ceramics with red marrow into quadriceps femoris muscle of rabbits, a huge amount of new bone and marrow formed in these sites on and in the ceramics 4 weeks after transplantation. These results showed an excellent biocompatibility between TCP ceramics and marrow and an excellent osteogenic effect in the compound transplantation. The mechanism of classification and clinical significance about the compound transplantation were discussed.

A retrospective analysis of the gluteal muscles contracture and discussion of the relative problems

SummaryThe operation methods, clinical classification, postoperative function exercise of gluteal muscles contracture were investigated. Clinically and retrospectively, treatment of 1280 patients with gluteal muscles contracture, being subjected to a “Z-shaped” release lengthening operation and efficiency exercise, was clearly standardized. All the cases were followed up from 3 months to 2 years with the effective rate being 100 %, the cure rate ieing 98.5 %, the recent complications being 5 %, and the far complications being 0.2 %. It was concluded that the clear diagnosis combined with standarized operation and efficiency functional exercise could greatly improve the therapeutic effects of gluteal muscles contracture.

Cloning and expression of rat transforming growth factor β1 cDNA in osteoblasts

SummaryRat transforming growth factor β1 (rTGFβ1) cDNA from rat lymphocytes was cloned by RT-PCR and inserted into pcDNA3 to construct an eukaryotic expression vector, which was named pcDNA3-TGFβ1. The cloned gene was confirmed to code rat TGFβ1 by restriction enzyme analysis. pcDNA3-TGFβ1 plasmid was transfected into rat osteoblasts by using liposome-mediated gene transfer technique and the expression of TGFβ1 was detected by using immunohistochemical staining assay. It was found that the rat TGFβ1 expression product was obviously detectable in the transfected osteoblasts in 48 h. High expression of TGFβ1 was obtained in the rat osteoblasts in which the constructed TGFβ1 expression vector was transfected.

Macrophages in degradation of calcium phosphate compound artificial bone: Anin vitro study

SummaryThe isolated mice peritoneal macrophages in degradation of calcium phosphate compound artificial bone-collagen/hydroxylapatite (CHA), hydroxylapatite (HA), beta-tricalcium phosphate (TCP) ceramics, have been studied by use of both Ca++, P concentration assay in cultured supernatant and scanning electron microscopy (SEM). The solubility of Ca+ +, composition of materials increased more significantly when macrophages were inoculated than when macrophages were not seeded (P< 0.001), and it was shown that the ground materials were wrapped and phagocytized or resorbed extracellularly by macrophages under SEM, suggesting that macrophages could mediate the degradation of calcium phosphate compound artificial bone by phagocytizing and/or degrading extracellularly.

The experimental study on mixed culture of osteoblasts and tricalcium phosphate ceramicsin vitro

SummaryTo study the effects of tricalcium phosphate (TCP) ceramics on osteoblasts, the rat osteoblasts were cultured with the TCP ceramicsin vitro. Scanning electron microscopy and the colorimetric methyl-thiazol-tetrazolium assay showed that the osteoblasts could adhere well to the surface of the ceramics and the culture dish, and the proliferation of the cells was not inhibited. The results demonstrated that TCP ceramics possessed an excellent cytocompatibility with the osteoblasts, and had some promoting effects on proliferation of osteoblasts.

Effect of absorbable hydroxyapatite/poly DL lactide rods on experimental fracture healing

SummaryIn order to investigate the effect of a new institute-designed absorbable hydroxyapatite microparticles/poly-DL-lactide (HA/PDLLA) fracture fixation devices on experimental fracture healing, 25 rabbits with a transverse transcondylar osteotomy of the distal femur were fixed intramedullary by a HA/PDLLA rod (4. 5 mm in diameter, 30–40 mm in length). The follow-up time lasted 1, 2, 4, 6 and 12 week(s). Roentgenographic, histological and ultrastructural analyses were conducted. The results showed that all osteotomies united within 6 weeks without delay. No accumulation of inflammatory cells was seen. Ultrastructural studies showed that polymorphonuclear neutrophils and macrophages were observed mainly at the 1st week, but only few were noted at the 2nd week. The inflammatory and debridement stages were not prolonged. Large amount of active fibroblasts and some chondroblasts were observed at the 2nd week, suggesting a fibrous callus stage. The main cellularity at 4th week was osteoblasts and osteocytes. Part of osteocytes had already entered the static stage at the 6th week. Our experiment showed that the HA/PDLLA had good biocompatibility, sufficient mechanical streugth and caused no delay to the fracture healing.

Reinnervation of free transferred muscle by nerve suture and nerve implantation in combination—An experimental study

SummaryThe authors have designed a method of combining nerve suture and nerve implantation to improve reinnervation and functional recovery of free transferred muscles. Experimental results on EMG recording, muscle power, muscle weight and histologic construction showed better recovery, compared with either mere nerve suture or nerve implantation. The change of motor end-plates with cholinesterase staining indicates more perfect reinnervation. The clinical significance of this method and certain considerations in performance are discussed in this paper.