羟氨苄青霉素引起大疱性类天疱疮样疹

https://www.oarsijournal.com/article/S1063-4584(10)00238-4/pdf

The OARSI histopathology initiative – recommendations for histological assessments of osteoarthritis in the mouse

Current strategies of regenerative medicine are focused on the restoration of pathologically altered tissue architectures by transplantation of cells in combination with supportive scaffolds and biomolecules. In recent years, considerable interest has been given to biologically active scaffolds which are based on similar analogs of the extracellular matrix that have induced synthesis of tissues and organs. To restore function or regenerate tissue, a scaffold is necessary that will act as a temporary matrix for cell proliferation and extracellular matrix deposition, with subsequent ingrowth until the tissues are totally restored or regenerated. Scaffolds have been used for tissue engineering such as bone, cartilage, ligament, skin, vascular tissues, neural tissues, and skeletal muscle and as vehicle for the controlled delivery of drugs, proteins, and DNA. Various technologies come together to construct porous scaffolds to regenerate the tissues/organs and also for controlled and targeted release of bioactive agents in tissue engineering applications. In this paper, an overview of the different types of scaffolds with their material properties is discussed. The fabrication technologies for tissue engineering scaffolds, including the basic and conventional techniques to the more recent ones, are tabulated.

/pdf/polymeric-scaffolds-in-tissue-engineering-application-a-2sbenjc1po.pdf

Polymeric scaffolds in tissue engineering application: a review

Non-traumatic avascular necrosis of the femoral head

Fracture healing is a complex physiological process. With the latest advances made in molecular biology and genetics it is now known that it involves the spatial and temporal coordinated action of several different cell types, proteins and the expression of hundreds of genes working towards restoring its structural integrity without scar formation. The standard tissue engineering approach to provide solutions for impaired fracture healing, bone restoration and regeneration includes the utilisation of growth factors, scaffolds and mesenchymal stem cells (triangular concept). However, although the mechanical environment is discussed and is considered as an important element in bone regeneration, its importance is often underestimated and it is not always given the necessary attention. The available scientific evidence supports the view that all the 4 known factors contributing to bone restoration should be given an equal acknowledgment and recognition. The traditional discussed triangular concept therefore should be reconsidered and be accepted as the 'diamond concept'.

/pdf/fracture-healing-the-diamond-concept-4ol2keleam.pdf

Fracture healing: the diamond concept.

Biophysical input, including electric and electromagnetic fields, regulate the expression of genes in connective tissue cells for structural extracellular matrix (ECM) proteins resulting in an increase in cartilage and bone production. In in vivo models and clinical situations, this can be manifested as enhanced repair and a gain in mechanical properties of the repairing tissues. The mechanisms by which cell functions are regulated by biophysical input is the subject of this review. Biophysical interactions of electric and electromagnetic fields at the cell membrane are not well understood and require considerable additional study. We review information on transmembrane signaling, channel activation and receptor stimulation or blockade. Understanding physical interactions and transmembrane signaling will most likely be necessary to establish dosing paradigms and improve therapeutic efficacy. Considerable information has been generated on an intermediary mechanism of activity - growth factor stimulation. Electric and electromagnetic fields increase gene expression for, and synthesis of, growth factors and this may function to amplify field effects through autocrine and paracrine signaling. Electric and electromagnetic fields can produce a sustained upregulation of growth factors, which enhance, but do not disorganize endochondral bone formation. Progress in the areas of signal transduction and growth factor synthesis is very rapid and future directions are suggested.

Stimulation of growth factor synthesis by electric and electromagnetic fields.

Electric and electromagnetic fields are, collectively, one form of biophysical technique which regulate extracellular matrix (ECM) synthesis and may be useful in clinically stimulating repair of fractures and nonunions. Preclinical studies have shown that electric and electromagnetic fields regulate proteoglycan (PG) and collagen synthesis in models of endochondral ossification, and increase bone formation in vivo and in vitro. A substantial number of clinical studies have been done that suggest acceleration of bone formation and healing, particularly osteotomies and spine fusions, by electric and electromagnetic fields. Many of these studies have used randomized, placebo controlled designs. In osteotomy trials, greater bone density, trabecular maturation, and radiographic healing were observed in actively treated, compared with placebo-treated patients. In spine fusions, average union rates of 80% to 90% were observed in actively treated patients across numerous studies compared with 65% to 75% in placebo-treated patients. Uncontrolled, longitudinal cohort studies of delayed and nonunions report mean union rates of approximately 75% to 85% in fractures previously refractory to healing. The few randomized controlled studies in delayed and nonunions suggest improved results with electric and electromagnetic fields compared with placebo treatment, and equivalent to bone grafts.

Treatment of nonunions with electric and electromagnetic fields.

Avascular necrosis of the femoral head is a multifaceted process that leads to articular incongruity and subsequent osteoarthrosis of the joint. Clinicians concur that primary treatment should focus on preservation of the natural surface of the joint; however, there has not been a consensus on how best to accomplish this. While a number of therapeutic interventions have been reported, the efficacy has varied markedly and there have been few statistical comparisons. The purpose of the current study was to use statistical analysis to compare the results of two widely used procedures, vascularized fibular grafting (614 hips; 480 patients) and core decompression (ninety-eight hips; seventy-two patients), for the treatment of avascular necrosis. The patients were stratified according to age and the stage of disease, and a survival analysis was performed with total hip arthroplasty as the end point for failure. None of the eleven hips that had Ficat stage-I disease needed a total joint replacement after being treated with either regimen. Analysis of the hips that had stage-II disease revealed rates of survival, at fifty months, of 65 per cent (twenty-eight of forty-three hips) after core decompression and 89 per cent (ninety-nine of 111 hips) after vascularized fibular grafting. For the hips that had Ficat stage-III disease, the rates of survival at fifty months were 21 per cent (ten of forty-seven hips) after core decompression and 81 per cent (405 of 500 hips) after vascularized fibular grafting. Among the hips that had Ficat stage-II or III disease, the rate of eventual total joint arthroplasty after vascularized fibular grafting was significantly lower than that after core decompression (p < 0.0001). The results indicate that the increased morbidity associated with vascularized fibular grafting is justified by the associated delay in or prevention of articular collapse in hips that have stage-II or III disease.

Survival analysis of hips treated with core decompression or vascularized fibular grafting because of Avascular necrosis

Sequential release of bioactive IGF-I and TGF-β1 from PLGA microsphere-based scaffolds

Once roentgenographic changes are apparent, osteonecrosis of the femoral head in the adult generally progresses to osteoarthritis within two to three years. A variety of conservative surgical procedures have been devised to conserve the femoral head with varying success. This study examines the effectiveness of pulsing electromagnetic fields and core decompression in the treatment of osteonecrosis of the femoral head. Both techniques reduce the incidence of clinical and roentgenographic progression. Exposure to pulsing electromagnetic fields appears to be more effective in hips with Ficat II lesions than in hips with more advanced lesions.

Roy K. Aaron

Papers

Stimulation of growth factor synthesis by electric and electromagnetic fields.

Treatment of nonunions with electric and electromagnetic fields.

Survival analysis of hips treated with core decompression or vascularized fibular grafting because of Avascular necrosis

Sequential release of bioactive IGF-I and TGF-β1 from PLGA microsphere-based scaffolds

The conservative treatment of osteonecrosis of the femoral head. A comparison of core decompression and pulsing electromagnetic fields.