bluuebunny/crossref_metadata_2025_split huggingface dataset:
Antibiotic‐loaded biodegradable bone cement for prophylaxis and treatment of experimental osteomyelitis in rats
Authors: Gerhart T. N. , Roux R. D. , Hanff P. A. , Horowitz G. L. , Renshaw A. A. , Hayes W. C. 
Published: February 2005

AbstractA biodegradable, particulate composite bone cement containing gentamicin and vancomycin was used for both treatment and prophylaxis of Staphylococus aureus osteomyelitis in rats. Osteomyelitis was established by inoculating S. aureus into holes that were drilled in the proximal tibiae and were filled with polymethylmethacrylate (PMMA) cylinders. The cylinders were left in place for 3 weeks. The infections were serially evaluated by clinical and radiographic examination and by quantitative culture for colony forming units (CFUs) at the time the rats were killed. For treatment, cements containing antibiotic were implanted in animals that had established osteomyelitis and were left in place for an additional 3 weeks. Sites treated with biodegradable cement containing antibiotics exhibited significantly fewer CFUs in comparison with controls (p ≤ 0.01). Sites treated prophylactically with the biodegradable cement developed no infections as evaluated by clinical or radiographic criteria or by quantitative culture. At this relatively early time, no significant difference in therapeutic effectiveness was found when either the biodegradable cement or PMMA was used as a carrier for antibiotics.
A standardized experimental fracture in the mouse tibia
Authors: Hiltunen Ari , Vuorio Eero , Aro Hannu T. 
Published: February 2005

AbstractThe increased use of transgenic mice as experimental animals provides new opportunities to study the biology of fracture repair. We have developed a technique for the production of a standard closed experimental fracture in the mouse tibia. A 0.2 mm stainless‐steel rod was introduced into the medullary cavity and the pre‐nailed tibial shaft was fractured by an impact device, which resulted in a reproducible transverse or slightly oblique fracture pattern. The intramedullary rod maintained axial alignment, and the fractures united without displacement. On the basis of measurements of callus geometry, four‐point bending tests, biochemical analyses, and quantitative histology, the progress of callus formation and remodeling occurred in a predictable sequence of healing phases. The ultimate bending loads of the fractures increased with time, reaching 74% of the strength of intact control tibias in 4 weeks. The stiffness values of the fractures returned to normal levels and, as determined radiographically, the fractures united by external callus in 4 weeks. Radiographically, callus size, cross‐sectional callus area, and callus mass peaked at 2 weeks and decreased thereafter, indicating the start of external remodeling. Histologically, the amount of mesenchymal tissue was maximal at days 5 and 7. The callus cartilage area peaked at day 9; at its maximum, it accounted for 46% of the total callus area. Early periosteal formation of membranous new bone, followed by endochondral ossification, resulted in a linear increase of callus bone during the healing process. The healing sequence of the mouse tibial fracture was similar to that seen in the rat tibia. The major difference is the small size of the mouse, which makes the surgical technique and anesthetic procedures more demanding.
Mechanical characteristics of proximal femoral reconstruction after 50% resection
Authors: Markel Mark D. , Gottsauner‐Wolf Florian , Rock Michael G. , Frassica Frank J. , Chao Edmund Y. S. 
Published: February 2005

AbstractSix techniques of proximal femoral replacement were compared in vitro with the use of compression, bending, and torsional testing in a canine model. One femur of each pair was osteotomized in the midshaft region, and the proximal portion was replaced with one of six techniques. These techniques included (a) a segmental proximal femoral endoprosthesis cemented into the distal femur with no allograft (technique Es); (b) a long‐stem endoprosthesis press‐fit into an allograft and cemented into the distal femur with a transverse osteotomy (technique AT); (c) the same construct as technique AT, but with a step‐cut at the osteotomy (technique AS); (d) a long‐stem endoprosthesis interlocked into an allograft and cemented into the distal femur with a transverse osteotomy (technique AI); (e) a short‐stem endoprosthesis cemented into an allograft combined with one plate laterally stabilizing the allograft to the distal femur with a transverse osteotomy (technique AP1); and (f) the same construct as technique AP1, but with an additional plate cranially (technique AP2). A long‐stem endoprosthesis cemented into the contralateral intact femur served as the control. Techniques that involved a long‐stem endoprosthesis and cementing distally (AT, AS, and AI) were more resistant in torsion than the plated replacement techniques (AP1 and AP2). The segmental replacement construct (ES) was equal to or stronger than all other techniques under each testing condition. In torsion, the addition of a step‐cut (AS) significantly lowered angular displacement of the reconstruction when compared with the reconstruction with a transverse osteotomy (AT) (p ≤ 0.05). Bones with one‐plate fixation (AP1) were significantly weaker in torsional stiffness and maximum torque and in mediolateral bending (p ≤ 0.05) than all other techniques. The addition of a second plate (AP2) increased the mechanical properties of the construct so that it was greater than the one‐plate method and was equal to (bending and compression) or still weaker (torsion) than the other techniques. The results indicate that segmental replacement methods and allograft/endoprosthetic composites that involve long‐stem endoprostheses fixed with cement are mechanically superior to methods that involve short‐stem endoprostheses with single or double plating at the osteotomy sites.
Distribution of integrins and their matrix ligands in osteogenic sarcomas
Authors: Kawaguchi Satoshi , Uede Toshimitsu 
Published: February 2005

AbstractWe studies the expression of the members of the β1 integrin family and extracellular matrix ligands in osteosarcoma tissues. Immunostaining of primary osteosarcomas with use of specific antibodies for α1‐α6 integrin subunits, fibronectin, type‐I collagen, and laminin gave characteristic patterns: despite the diffuse expression of type‐I collagen in all 16 osteosarcomas, collagen receptors were detected in only one. Laminin and laminin receptors were expressed poorly. In contrast, the α4 and α5 fibronectin receptors were found in 100 and 75%, respectively, which correlates very well with the strong expression of fibronectin in the stroma. The other ligand for α4, vascular cell adhesion molecule‐1, was not expressed in the seven specimens tested. Therefore, primary osteosarcomas closely interact with fibronectin through α4 and possibly α5 subunits of the β1 integrin. We also examined the expression the expression was detected in all six specimens, however, the change varied. In contrast, osteosarcoma cells obtained from invasive portions of tumors exhibited new and augmented expression of certain integrins in two of the three cases in which their ligands were also expressed.
Adrenergic control mechanisms of blood flow in a vascularized canine tibial allograft
Authors: Moran Christopher G. , McGrory Brian J. , Roorda Jan , Wood Michael B. 
Published: February 2005

AbstractA vascularized canine tibial allograft was used to study the alpha‐adrenoreceptor subtypes of the microcirculation of bone. Bone transplantation was performed on six dogs, and the bone blood flow was estimated with the use of serial injections of radiolabeled 15 μm microspheres. After microvascular anastomosis, the mean cortical blood flow in the allografted tibia was 3.6 ± 2.1 ml/100 g/min. Alpha1‐adrenoreceptor blockade, with prazosin, caused an increase in normalized blood flow in five allografts and a slight decrease in one allograft. The mean increase was 32 ± 48%, but this was not statistically significant (p ≤ 0.2). The addition of an alpha2‐adrenoreceptor blockade, with rauwolszin, resulted in a significant increase (132 ± 88%) in normalized blood flow in all allografts (p ≤ 0.02). This ex vivo experiment confirms that both alpha1 and alpha2 adrenergic mechanisms play a role in controlling bone blood flow in centrally denervated allografts.
Comparison of demineralized allogeneic bone matrix grafting (the Urist procedure) and the Ilizarov procedure in large diaphyseal defects in sheep
Authors: Ehrnberg Anders , De Pablos Julio , Martinez‐Lotti Gabriel , Kreicbergs Andris , Nilsson Olle 
Published: February 2005

AbstractThe bone inductive capability of the Urist and Ilizarov procedures was compared in the repair of large diaphyseal defects in sheep. In 30 animals, a 4 cm segmental defect was created in the middle portion of the right femur and was stabilized with an external fixator. The sheep were divided into four groups according to the type of reconstruction of the defect. In group 1, a demineralized allogeneic bone matrix (DABM) cylinder was used; in group 2, DABM chips; and in group 3, gradual transport of a piece of bone detached from the proximal femoral fragment was used to fill the defect. Group 4 served as a control (the defect was left empty). New bone formation was assessed by serial radiographs until the time of death at 2 or 4 months. Postmortem specimens were analyzed with respect to bone mineral content, uptake of isotopes (45Ca and 3H‐proline), and histology. The first signs of new bone formation were radiographically evident at 4 weeks. In the two groups in which reconstruction involved DABM (Urist procedures), new bone failed to form in eight of the 13 animals. Full bridging of the defect was observed at 8 weeks in one animal with a DABM cylinder and two with DABM chips. No decisive difference in bone yield could be demonstrated between the two Urist procedures. In the group treated with the Ilizarov procedure, new bone formation consistently occurred at a high rate; full bridging of the defect was observed in seven of the eight animals. Bone mineral scanning and histologic analysis essentially confirmed the radiographic results. Uptake of isotopes was selectively analyzed in two sheep from each experimental group in which new bone formation was exhibited in the defect; new bone formation was increased compared with that in the contralateral femur but was equal among the three experimental groups. Our study shows that gradual transport of a detached piece of autogeneic bone (Ilizarov procedure) is more effective than implantation of DABM (Urist procedure) in eliciting new bone formation in large diaphyseal defects in sheep. The variable bone induction by DABM may be explained by differences in host immune responses to the implants.
A mechanical comparison of gluteus medius attachment methods in a canine model
Authors: Markel Mark D. , Rock Michael G. , Bergenthal D. Stephanie , Young David R. , Vanderby Ray , Chao Edmund Y. S. 
Published: February 2005

AbstractSeven techniques of gluteus medius attachment were compared in vitro in a canine model. Four methods were used for tendon to tendon attachment: (a) two modified Bunnell‐Mayer stutures, (b) two Kessler locking loop sutures, (c) two horizontal mattress sutures, and (d) two sutures with a looped suture technique. The two methods of tendon to bone attachment were repair with a 1 cm spiked staple and repair with a spiked washer and screw, and the method of bone to bone attachment involved two figure‐eight cerclage wires. The colitralateral limb served as a control. Compared with the bone to bone attachment, the four tendon to tendon attachments and the two tendon to bone attachments had significantly less strength (31 and 30% of the ultimate load for bone to bone repair, respectively) and tensile stiffness (24 and 39% of the tensile stiffness for bone to bone attachment, respectively) (p ≤ 0.0001). The control specimens were significantly stronger and stiffer than all specimens (p ≤ 0.05) except those that had bone to bone fixation. There were no significant differences among the four tendon to tendon suture repairs with regard to either strength or stiffness; the values ranged from 28–45% of those of the controls. Among the tendon to bone repairs, fixation with a spiked washer and screw was significantly stronger than that with a spiked staple (p = 0.032), but there was no difference between these two techniques with regard to stiffness.
Pleiotrophin is an abundant protein in dissociative extracts of bovine fetal epiphyseal cartilage and nasal cartilage from newborns
Authors: Neame Peter J. , Young Carmen N. , Brock Charles W. , Treep James T. , Ganey Timothy M. , Sasse Joachim , Rosenberg Lawrence C. 
Published: February 2005

AbstractAn abundant protein that is identical to the growth‐associated protein pleiotrophin (PTN) has been isolated from dissociative extracts of bovine nasal and fetal epiphyseal cartilage. The yield from these tissues was at least 15 μg/g wet weight of cartilage. PTN was absent or was present only in trace amounts in mature articular cartilage. An analysis of tryptic fragments of PTN, held together with disulfide bonds, did not indicate any set pattern of cystine cross‐links, which suggests a propensity for rapid refolding of the protein. PTN could not be isolated from thin (10 μm) slices of nasal cartilage in physiological extraction buffers, which indicates that it was tightly associated with the cell surface, was tightly associated with nonextractable matrix, or was an intracellular protein. Its appearance in various extraction media parallels that of histone H2b, a nucleosomal protein; this suggests a possible intracellular location for the protein. Immunohistochemical analysis of its distribution in fetal epiphysis indicated that it is associated with chondrocytes.
In vivo quantification of proteoglycan synthesis in articular cartilage of different topographical areas in the murine knee joint
Authors: van Osch G. J. V. M. , van der Kraan P. M. , van den Berg W. B. 
Published: February 2005

AbstractWe developed a method of quantitative measurement of the synthesis of proteoglycans in different areas of the patella and the tibial plateau of the mouse. After incorporation of radioactive sulfate in vivo, the patella was divided with a punch into a central and a peripheral part. A central medial and a central lateral part were taken from the tibial plateau to measure the synthesis of proteoglycans. The synthesis was determined in normal joints and at different intervals after intra‐articular injection of sodium iodoacetate and was compared with autoradiographs of whole joint sections. Although considerable variation in sulfate incorporation was found within a group on particular days after induction of osteoarthritis, the variation among experiments was low. Comparison with autoradiographs showed that this new method makes it possible to quantify proteoglycan synthesis by incorporation of radioactive sulfate in different topographical areas of the murine knee joint.
Changes in bone in a model of spinal cord injury
Authors: Hill Esther L. , Martin R. Bruce , Gunther Elizabeth , Morey‐Holton Emily , Holets Vicky R. 
Published: February 2005

AbstractBone calcium, histomorphometry, and mechanical strength were evaluated in a model of spinal cord injury. Cortical bone area and rates of formation and apposition at the tibiofibular junction (TFJ) and midshaft of the humerus were measured at 35–42, 42–77, and 77–94 days after transection of the spinal cord. All comparisons were between the animals with a spinal lesion and control animals. A 0.34% difference in the length of the tibia of the two groups of animals was observed, the dry weight of the tibia was 28.4% less in rats with a lesion, and there was no significant difference in the amount of calcium per milligram of bone. At 35 days after surgery, the cortical area in the midshaft of the humerus was slightly less (11%) in rats with a lesion, but by 94 days there was no difference in cortical or medullary area. The final (day 94) cortical area at the TFJ in rats with a lesion was less than that in the controls. Bone formation at the TFJ was similar in both groups in the period of 35–42 days and was similar at 77–94 days in the animals with a lesion, and rates of formation and apposition were greater in the humerus of rats with a lesion; the rates did not differ significantly between groups at either site. At 94 days, trabecular bone area in the tibial metaphysis was 41% less in rats with a lesion. Mechanical parameters were significantly less in the femora, but not the humeri, of rats with a lesion.
Effect of controlled local release of sodium fluoride on bone formation: Filling a defect in the proximal femoral cortex
Authors: McCormack A. P. , Anderson P. A. , Tencer A. F. 
Published: February 2005

AbstractTo assess the effect of sodium fluoride (NaF) in the healing of a defect in cortical bone, an experimental model was created by the drilling of 5.0 mm holes in the proximal ends of both femora of 12 adult male New Zealand White rabbits. An interlocking intramedullary implant constructed of poly(d,l‐lactic acid) containing NaF was placed in the right femur and an identical implant without NaF (sham), in the left. The implant in the right femur was designed to release NaF in a controlled manner over the duration of the experiment. Ten weeks after implantation, the specimens were removed and were tested in torsion. The mechanical properties were not significantly different between the groups. The femora exposed to NaF had an 18.6% increase in intact cortex near the defect (p = 0.023), however, the deposition of mineralized bone within the defect was not significantly greater. In fact, healing appeared to be impaired by the presence of NaF. There was complete closure of the defect in all but one of the femora with a sham implant, but the tissue had not yet calcified. In contrast, only one femoral defect exposed to NaF had closed. Examination of the material filling the defects of the femora exposed to NaF showed that it was predominantly uncalcified osteogenic mesenchymal tissue.
In vitro pharmacokinetics of antibiotic release from locally implantable materials
Authors: Miclau Theodore , Dahners Laurence E. , Lindsey Ronald W. 
Published: February 2005

AbstractLocal deposition of antibiotics has became increasingly popular in the management of open fractures or osteomyelitis, and several substances have been employed as the vehicle for delivery. Although the elution characteristics of some substances have been documented, a comparative study of the characteristics of the commonly used substances could establish the clinical indications for particular vehicles. Cylindrical pellets of uniform size (6 × 4 mm) were prepared from bone graft (BG), demineralized bone matrix (DBM), plaster of Paris (POP), or polymethylmethacrylate (PMMA), with 25 mg of tobramycin/g of substance in each pellet. The pellets were suspended in phosphate buffered saline, and the antibiotic concentration in the buffer was determined at various time intervals by an enzyme immunoassay. BG and DBM eluted 70 and 45% of their antibiotic load by 24 h, and negligible amounts were detected at 1 week; POP released 17% of its load by 24 h, with trace amounts detected at 3 weeks; and PMMA eluted 7% at 24 h, with trace amounts detected for as long as 14 days. These findings suggest that the optimal vehicle for local deposition of antibiotic depends on the clinical setting. BG and DBM may be best employed when brief antibiotic coverage is required (as for acute contaminated open fractures), whereas POP and PMMA may be better suited for long‐term coverage (such as for established osteomyelitis).
Effects of ascorbic acid, calcitriol, and retinoic acid on the differentiation of preosteoblasts
Authors: Choong Peter F. M. , Martin T. John , Ng Kong Wah 
Published: February 2005

AbstractThe responses of the immortalized rat preosteoblast UMR‐201‐10B to ascorbic acid (AA), 1,25(OH)2D3 (calcitriol), and retinoic acid (RA) were examined. UMR‐201‐10B cells have an undetectable basal alkaline phosphatase (ALP) activity that is induced after 24 h of treatment with 10−6 M RA (4.64 ± 0.06 μmol/h/mg of protein). The addition of 10−8 M calcitriol resulted in a slight induction of ALP activity after 72 h (0.43 ± 0.07 μmol/h/mg of protein). When calcitriol was added to RA, however, over the same period ALP activity was enhanced significantly compared with treatment with RA alone (RA and calcitriol, 12.29 ± 0.86 μmol/h/mg of protein). Treatment with AA (50 μg/ml) alone had no effect on ALP activity but increased RA‐induced ALP activity to 6.78 ± 0.28 μmol/h/mg of protein at 24 h. In contrast, AA inhibited calcitriol‐induced ALP activity after 7 days of combined treatment with calcitriol (calcitriol, 7.73 ± 0.16 μmol/h/mg of protein; AA and calcitriol, 1.44 ± 0.06 μmol/h/mg of protein). Individually, RA and calcitriol induced mRNA expression for ALP, matrix‐gla protein (MGP), and osteopontin (OP). The steady state level of pro‐α1(I) collagen mRNA also was increased significantly by treatment with RA and AA individually. The combination of RA and calcitriol had a synergistic effect on ALP, OP, and especially MGP mRNA expression but significantly reduced the expression of pro‐α1(I) collagen mRNA. AA enhanced the effect of RA on the expression of pro‐α1(I) collagen, MGP, and ALP mRNAs as well as the effect of calcitriol on OP and MGP. The addition of AA to RA resulted in a decrease in the steady state level of OP, whereas its cotreatment with calcitriol caused a decrease in pro‐α1(I) collagen and ALP mRNA. In conclusion, these studies identify RA, calcitriol, and AA as regulators of differentiated osteoblast function.
Associations and dissociations between serum bone gla protein and alkaline phosphatase in skeletal metabolism
Authors: Parthemore J. G. , Burton D. W. , Deftos L. J. 
Published: February 2005

AbstractSerum bone Gla protein (BGP) and alkaline phosphatase (AP) activity were compared for the assessment of skeletal status in 11 normal pregnant women, 12 normal women on days 3 and 13 of the menstrual cycle, five postmenopasual women before and after 1 month of treatment with ethinyl estradiol (20 μg/day), five patients with cancer and hypercalcemia during treatment with calcitonin, and one patient with Paget disease during treatment with Plicamycin. BGP and AP correlated with each other only in the pregnant women. In all other circumstances, there was no correlation between these two serum osteoblast products. Furthermore, there were condisitions in which the two measurements became discordant. These studies demonstrate that BGP and AP commonly are dissociated when used as measurements of skeletal status. Although both are osteoblast products, BGP and AP probably reflect different aspects of osteoblast differentiation and function.