摘要:

AbstractThe cells responsible for skeletal growth are the chondrocytes of the cartilaginous growth plate. These cells differentiate through a series of maturational stages, establishing different zones in the growth plate. Among the major functions of these cells is the production of appropriate extracellular matrix, primarily composed of collagens and proteoglycans. To determine whether matrix synthesis varies with respect to maturational stage and in which cell populations different collagens are expressed, bovine growth plates were analyzed byin situhybridization ot mRNA and by Northern blot hybridization. The most abundant collagen mRNA in the growth plate was type‐II collagen. This mRNA was present at relatively low levels in the most immature cells of the growth plate but increased several‐fold as cells entered the proliferative stage and remained high through subsequent phases of maturation. Type‐XI collagen mRNA and mRNA for the cartilage‐characteristic proteoglycan, aggrecan, were codistributed with the type‐II collagen mRNA; however, both were present in much smaller quantities. Type‐X procollagen mRNA was localized to chondrocytes late in their maturation and was expressed at levels similar to the expression of type‐II collagen.In situhybridization of serial sections revealed that growth plate chondrocytes in their more mature stages contain both type‐II and type‐X collagen mRNA. Type‐I collagen mRNA was not observed in growth plate chondrocytes at any maturational stage; rather, it was localized to a morphologically distinct population of cells attached to calcifying cartilage septa in the region of vascular invasion. These data indicate that the genes for major matrix constituents synthesized by the growth plate in some cases are expressed differentially at different stages of cellular maturation and in other cases are expressed coordinately. The pattern of mRNA expression suggests possible mechanisms

ISSN:0736-0266    

DOI:10.1002/jor.1100120102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThe ability of the chondrocytes in intact bovine articular cartilage (AC) to synthesize glycosaminoglycans (GAG) during short‐term refrigerated storage was examined. Closed and exposed bovine carpometacarpal joints were stored in a refrigerator for 4 hours, 1 day, 3 days, 5 days, or 7 days after the death of the animal. Full‐thickness 6 mm diameter cartilage disks were obtained from each joint, incubated in Na235SO4, digested, and assayed for GAG production. Similarly incubated cartilage samples were processed for autoradiography as a qualitative determination of35S uptake by chondrocytes. All refrigerated samples of AC showed signs of some cellular metabolic activity. Only at 7 days did chondrocytes demonstrate a significant decline in activity. For all five storage periods, AC from joints exposed to nutrient media synthesized more GAG than cartilage from matched closed joints. These results suggest that some chondrocytes in AC destined for osteoarticular allografting retain the ability to synthesize GAG for as long as 5 days of refrigerated storage and that this synthesis is stimulated by storage of the joint surfaces in a sterile nutrient solution. While the implications of the chondrocytes' survival and metabolism for osteochondral allograft transplantation are unknown, these data indicate that intact bovine AC retains some metabolic activity for several days under the conditions described and would carry on this activity if transplanted within that period of t

ISSN:0736-0266    

DOI:10.1002/jor.1100120103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractStromelysin‐1, tissue inhibitor of metalloproteinases‐1 (TIMP‐1), and proteoglycan fragments were quantified in knee synovial fluid samples in a cross‐sectional study of patients who had injury to the anterior cruciate ligament or the meniscus. The average concentrations of stromelysin‐1 and TIMP‐1 increased 25‐fold and 10‐fold within the first day after the trauma, respectively, and the concentration of proteoglycan fragments increased 4‐fold. From approximately 1‐6 months after injury, the levels of these markers were higher after injury to the cruciate ligament than after injury to the meniscus. From 6 months to 18 years after trauma, however, the levels of stromelysin‐1 and TIMP‐1 in patients who had an injury to the ligament were the same as the levels in patients who had a meniscal lesion. but the levels were increased compared with those for a reference group of healthy volunteers. The molar balance of stromelysin‐1 to TIMP‐1 in synovial fluid in both groups of injured joints changed from a balance representing an excess of free inhibitor in the normal joint to one representing an excess of free enzyme in the injured joint. The increased release of these markers to joint fluid both early and late after trauma may be caused by a change in the loading patterns in the knee with an injured ligament or meniscus or by synovitis induced by bleeding. The increased release may be associated with the frequent development of posttraumatic osteoarthritis in p

ISSN:0736-0266    

DOI:10.1002/jor.1100120104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractAn immunocytochemical method was used to localise osteocalcin‐producing cells during fracture healing in a rabbit model. In preliminary studies, tibial growth plates from young rabbits were used as a source of new bone formation, in order to determine the optimal tissue preparatory techniques. In the present study, a tibial shaft fracture was created in adult rabbits to study closed fracture healing. An indirect peroxidase method was used to stain paraffin‐embedded tissue sections for osteocalcin. Osteocalcin‐producing cells were positively identified at the periosteal and endosteal surfaces near the fracture site. Osteocalcin staining was not demonstrated in the surrounding soft tissues. At the interface between newly formed bone trabeculae and the cartilage layer within the callus, chondrocytic cells consistently showed localisation of osteocalcin. Within cartilaginous areas of the callus, some chondrocytes showed positive staining for osteocalcin. These cells were often seen in theproximity of blood vessels. The findings suggest that during fracture healing, under certain conditions, chondrocytes are capable of producing osteocalcin and thus could be considered capable of possible transformation into osteob

ISSN:0736-0266    

DOI:10.1002/jor.1100120105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractBilateral closed femoral shaft fractures were made in 22 male Long‐Evans rats. In 16 animals, ultrasound was applied to one limb for 15 minutes daily 10 times within the first 14 postoperative days. The treated limbs received a 200 μsec burst of 1.5 or 0.5 MHz sine waves repeated at 1.0 KHz at a spatial average and temporal average intensity of 30 mW/cm2. The contralateral limb of each animal served as a nontreated control. Six remaining animals with fractures and six additional animals without fractures received sham ultrasound treatment to control for the effects of anesthesia and handling. Fracture repair was evaluated on postoperative day 21 by radiography, mechanical testing in torsion, and histology. Five of 16 ultrasound‐treated fractures showed obliteration of the fracture gap on radiographs, whereas none of the 28 controls did. The average maximum torque of fractures treated with either signal was 22% greater than that of the contralateral controls (p<0.05). The stiffness of treated fractures was greater than that of control fractures, but the difference was significant only in animals treated with the 1.5 MHz signal (p<0.02). Sham treatment did not affect repair in the control group. These results indicate that low‐intensity pulsed ultrasound at either 0.5 or 1.5 MHz can accelerate fracture repair at 21 days in this highly controlled

ISSN:0736-0266    

DOI:10.1002/jor.1100120106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThe cellular injury produced by reperfusion of ischemic tissue with oxygen‐rich blood has been studied in numerous tissues but has not been investigated extensively in thermoregulatory tissue. This study was designed (a) to compare 4 and 6 hours of ischemia to document the evidence of impaired capillary perfusion after resumption of blood flow (reperfusion injury) in a thermoregulatory end organ (the rabbit ear), and (b) to examine, with use of vital capillaroscopy (VC) and laser Doppler flowmetry (LDF), the altered microvascular blood flow in the rabbit ear after ischemia and reperfusion. One ear from each of five rabbits underwent warm ischemia for 4 hours. VC showed no deficits of capillary perfusion in these ears after reperfusion; LDF measurements in both ears also demonstrated no significant difference between control and reperfusion blood flow. One ear from each of eight additional rabbits underwent 6 hours of warm ischemia. LDF values were significantly reduced in the ischemic ear after reperfusion as compared with baseline measurements for that ear and as compared with the control ear. VC showed arrested perfusion and static plasma gaps within three to five capillaries per high‐power field (an area of 300 × 500 μm) in the ischemic ear and good perfusion of all vessels in the contralateral control ear. This evidence of reperfusion injury in a thermoregulatory end organ may help to explain the poor functional result that often occurs after replantation of an amputated

ISSN:0736-0266    

DOI:10.1002/jor.1100120107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractCalpain refers to Ca2+‐dependent neutral cysteine proteinase, which originally was thought to be an intracellular proteinase but recently has been shown to function extracellularly as well. This report describes the immunohistochemical demonstration of calpain and biochemical changes in the amount of calpain during fracture healing in rats. The tibiae of 6‐week‐old Wistar rats were fractured, and calluses were obtained 5–28 days after fracture. A frozen section of the fracture callus was stained by the immunoperoxidase method with use of polyclonal antibodies of calpains I and II. Positive staining was noted with the anti‐calpain II antibody in the perivascular areas, chondrocytes, and cartilage matrix in calluses at 5, 7, and 10 days. Less intense staining was seen in older calluses. The caseinolytic activity of calpain II reached its maximum on the 5th day, was high on the 7th and 10th days, and decreased rapidly thereafter. The quantity of calpain II was dependent on the process of fracture healing. It was concluded that calpain was working as one of the matrix proteinases in fractu

ISSN:0736-0266    

DOI:10.1002/jor.1100120108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractWe developed an experimental system to stimulate cell cultures by uniform and cyclic biaxial strain of the cell culture surface. The studies reported here were designed to determine the uniformity of the strain distribution, the suitability of the surface for the growth of human osteoblasts, and the effects of strain magnitude on cell proliferation and alkaline phosphatase (AP) activity. Subconfluent cell cultures were grown in rectangular silicone dishes that were stretched cyclically (1 Hz) in the long axis by an electromechanical apparatus that controlled peak stretch and cycle frequency. We applied cyclic strains (1.0, 2.4, 5.3, and 8.8% surface strains) for 15 minutes per day on 3 consecutive days. Phase contrast microscopy confirmed the transfer of dish surface strain to the cells. Stretching of the dish resulted in a homogeneous strain distribution that deviated approximately 0.05% from the applied strain. In comparison with plastic dishes, there was a 20% reduction of cell proliferation on the silicone substrate whereas morphology, AP activity, and total protein content of the cells were similar. The proliferation of human osteoblasts was increased significantly (16.4–100%) by 1% strains, although higher strain magnitudes had lesser (nonsignificant) effects or decreased the mitotic activity of the cells. AP and lactate dehydrogenase activities were not influenced significantly by cyclic strains. This study demonstrates that the cell stretching system is suitable for the investigation of the effects of well defined cyclic strain

ISSN:0736-0266    

DOI:10.1002/jor.1100120109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThe use of antibiotic‐impregnated polymethylmethacrylate (PMMA) cement beads for the local delivery of antibiotics in the treatment of chronic osteomyelitis has become a standard orthopaedic practice. The increasing resistance to antibiotics of organisms associated with orthopaedic infections has led to interest in the incorporation of more effective antibiotics into PMMA cement. Ciprofloxacin, a synthetic fluoroquinolone, is potent against a broad spectrum of bacteria associated with osteomyelitis. In this study, strands of ciprofloxacin‐impregnated PMMA cement beads were prepared with 0.2, 0.5, or 1.0 g of ciprofloxacin per 40 g of PMMA. The elution concentration of ciprofloxacin was at least 1–2 mcg/ml for 7 days (0.2 g), 30 days (0.5 g), and 42 days (1.0 g). This concentration is equivalent to the minimum inhibitory concentration for the common pathogens associated with osteomyelitis. Concurrent systemic and local ciprofloxacin therapy appears to be a method for the treatment of chronic osteomye

ISSN:0736-0266    

DOI:10.1002/jor.1100120110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractParticulate debris, including that from polymethylmethacrylate (PMMA) cement, is observed commonly in the membrane surrounding loose joint prostheses. Such debris is assumed to cause an inflammatory response and contributes to osteolysis and failure of the implant. A subcutaneous rat air‐pouch model was used to assess quantitatively thein vivoeffects of the size, morphology, and surface area of PMMA particles on the acute inflammatory response. PMMA particles were divided into three groups. In Group A, mechanical grinding of cured bone cement produced irregularly shaped particles; Group B included spherical particles of PMMA powder (Simplex P); and Group C consisted of commercially prepared spherical latex particles. All three groups had two size distributions:<20 μm and 50–350 μm. For a given mass or dose, the small, irregularly shaped mechanically produced particles in Group A elicited a significantly greater inflammatory reaction than the large particles in Group A, as expressed by the release of tumor necrosis factor (TNF), neutral metalloprotease (NMP), and prostaglandin E2(PGE2) and the white blood cell (WBC) count within a 24‐hour period. Similar findings were seen in Group B. Particles in Group C were used to compare the effect of absolute numbers of large and small particles and surface area. Large (10–126 μm) spherical PMMA particles at a dose of 1.7 × 106particles/ml caused a significantly higher inflammatory response, as measured by WBC count and production of NMP and PGE2, than small (1–10 μm) spheres at a dose of 4 × 106particles/ml. However, the production of TNF in the rats was significantly increased with small particles (p<0.05) at a concentration 4‐fold less than that with the large particles (4 × 105compared with 1.7 × 106particles/ml). This finding may reflect a different cellular mechanism for the TNF component of the inflammatory response than is measured by WBC counts or by levels of PGE2and NMP. As the calculated surface area of the PMMA particles increased, a threshold level was reached, at which point the inflammatory response increased dramatically. The size of particles has a role in the prolongation and intensity of the release of specific cytokines. The total surface area of the particles appeared to be an important factor in determining the inflammatory response, as measured by WBC count,

ISSN:0736-0266    

DOI:10.1002/jor.1100120111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY