bluuebunny/crossref_metadata_2025 huggingface dataset:
In vivo analysis of microcirculation following closed soft‐tissue injury
Authors: Schaser Klaus‐D. , Vollmar Brigitte , Menger Michael D. , Schewior Lioba , Kroppenstedt Stefan N. , Raschke Michael , Lübbe Andreas S. , Haas Norbert P. , Mittlmeier Thomas
Published: February 2005

Major loss of tissue is an almost invariable consequence of severe closed soft‐tissue injury. Clinically, the extent of soft‐tissue trauma determines the outcome of complex injuries and significantly influences bone healing. With use of a new animal model, this study quantitatively analyzed microcirculation, i.e., nutritive perfusion and leukocyte‐endothelial cell interaction, in skeletal muscle after standardized closed soft‐tissue injury. By means of a computer‐assisted controlled‐impact technique, a severe standardized closed soft‐tissue injury was induced in the left hindlimb of 28 rats. The rats were assigned to four experimental groups (n = 7 per group) that differed by time of analysis (1.5, 24, 72, and 120 hours after injury); rats that were not injured served as controls (n = 7). Intramuscular pressure was measured, and microcirculation in the rat extensor digitorum longus muscle was analyzed by in vivo fluorescence microscopy, which allowed assessment of microvascular diameters, functional capillary density, number of rolling and adherent leukocytes in venules, and microvascular permeability. Edema weight gain was quantified by the ratio of wet to dry weight of the extensor digitorum longus muscle. Microvascular perfusion of the skeletal muscle was characterized by a significant reduction in functional capillary density, which was paralleled by an increase in capillary diameter throughout the 120 hours of observation when compared with the controls. Traumainduced inflammatory response was reflected by a markedly increased rolling and adherence of leukocytes, primarily restricted to the endothelium of postcapillary venules; this was accompanied by increased microvascular permeability, indicative of a substantial loss of endothelial integrity. The microcirculation surrounding the core of the damaged tissue area resembled that of ischemia‐reperfusion injury in skeletal muscle, i.e., heterogeneous capillary perfusion, pronounced microvascular leakage and adherence of leukocytes. Enhanced vascular leakage and leukocyte adherence (24‐72 hours after injury) coincided with the maximum intramuscular pressure (which was not indicative of compartment syndrome) and edema formation. These results demonstrate that initial changes, leading to ultimate tissue death, after closed soft‐tissue injury are caused on the microcirculatory level. This standardized model provides further insight into microvascular pathophysiology and cellular interactions following closed soft‐tissue injury. Thus, it is an adequate tool for testing novel therapeutic interventions.
Exercise affects the mechanical properties and histological appearance of equine articular cartilage
Authors: Murray R. C. , Zhu C. F. , Goodship A. E. , Lakhani K. H. , Agrawal C. M. , Athanasiou K. A.
Published: February 2005

Dorsal carpal osteochondral injury is a major cause of reduced performance in horses undergoing high‐intensity training. It was hypothesised that the mechanical behaviour and histology of cartilage are influenced by the intensity of exercise and by location within a joint. Relationships between histology and mechanical behaviour were identified in 2‐year‐old horses undergoing 19 weeks of high‐intensity treadmill training or low‐intensity exercise and then compared between groups. Dorsal and palmar test sites were identified on radial, intermediate, and third carpal articular surfaces after euthanasia. the mechanical properties of cartilage were determined with an automated creep indentation apparatus as previously described for equine cartilage. Cartilage morphology was assessed with use of sections stained with haematoxylin and eosin and toluidine blue. Dorsal cartilage was less permeable, thinner, and had a loss of chondrocyte alignment compared with palmar cartilage. Cartilage from strenuously trained horses showed more fibrillation and chondrocyte clusters than did cartilage from gently exercised animals. Dorsal radial carpal cartilage and third carpal cartilage of strenuously trained animals were significantly less stiff than that from gently exercised animals, and the former had reduced superficial toluidine blue staining compared with that from the gently exercised group. These results indicate that topographical and exercise‐related differences exist in the morphology and mechanical properties of carpal cartilage and suggest that strenuous training may lead to deterioration of cartilage at sites with a high clinical incidence of lesions.
Effects of low oxygen concentrations and metabolic inhibitors on proteoglycan and protein synthesis rates in the intervertebral disc
Authors: Ishihara Hirokazu , Urban Jill P. G.
Published: February 2005

The intervertebral disc is the largest asvacular structure in the body; consequently, there are steep gradients in O2 concentration, with PO2 falling to as low as 1% O2 in the centre of the disc. We investigated the effect of O2 concentration on the rates of O2 consumption, lactate production, and sulphate and proline incorporation in bovine caudal discs. We also investigated the effects of metabolic inhibitors of energy production pathways on tracer incorporation. Samples from the outer annulus and nucleus pulposus were incubated for 24 hours in 1‐21% O2. Rates were measured during the last 4 hours of incubation. As O2 concentration was reduced from 10 to 1% O2, O2 consumption rates fell by around 75% and lactate production rates almost doubled; the bovine discs thus showed a positive progressive Pasteur effect. Incorporation rates of [3H]proline and [35S]sulphate were lowest at 1% O2. In the nucleus, but not in the outer annulus, the rate of [35S]incorporation peaked at 5% O2, where it was 30% greater than at 21% O2 and 150% greater than at 1% O2. The competitive glycolysis inhibitor 2‐deoxyglucose, the oxidative phosphorylation uncoupler 2,4‐dinitrophenol, and the oxidative phosphorylation inhibitor sodium azide all markedly reduced sulphate incorporation. These results, together with previous measurements of CO2 production rates, suggest that a functionally significant fraction of the disc 's energy is supplied by oxidative phosphorylation. However, low levels of PO2, 2,4‐dinitrophenol, and sodium azide have been reported to reduce sulphate incorporation in articular cartilage, a tissue that derives its energy almost entirely from glycolysis.
Marrow‐derived progenitor cell injections enhance new bone formation during distraction
Authors: Richards Mark , Huibregtse Barbara A. , Caplan Arnold I. , Goulet James A. , Goldstein Steven A.
Published: February 2005

Bilateral femoral distraction was performed in rats to investigate whether injections of marrow derived mesenchymal progenitor cells could be used to facilitate new bone formation. The cells were isolated from whole marrow of 2‐6‐month‐old Sprague‐Dawley rats. One‐year‐old recipient Sprague‐Dawley rats were divided into five experimental groups. Rats in groups I, II, and III received injections of mesenchymal progenitor cells on days 6 (beginning), 12 (middle), and 18 (end of distraction) after surgery, respectively. Those in group IV received injections of serum and carrier gel alone, and those in group V received no injections. Distraction zones were harvested at 36 days and analyzed for new bone volume within the distraction gap by three‐dimensional microcomputed tomography. Significant increases in new bone volume were observed for femora injected with marrow‐derived progenitor cells compared with contralateral femora and controls (no injection). The timing of the cell injections appeared to have no effect on the experimental outcome. Histologic analyses demonstrated active formation of new trabecular bone with marked osteoblastic activity and osteoid production. No qualitative differences in histologic appearances of new bone among rats in any of the five groups were seen. The results of in vitro lysis assays indicated that donor and recipient rats were not completely syngenic, leaving some doubt as to the reasons for observed increases in new bone formation. Future work will focus on attempting to repeat these experiments in a fully syngenic rat model. This rat distraction model can be used to explore the molecular and cellular behavior of these progenitor cells in a clinically relevant in vivo environment.
Evaluation of the feasibility of and results of measuring health‐status changes in patients undergoing surgical treatment for skeletal metastases
Authors: Clohisy Denis R. , Le Chap T. , Cheng Edward Y. , Dykes Daryll C. , Thompson Roby C.
Published: February 2005

The goal of treating patients with skeletal metastases is to decrease pain and improve or maintain physical function. Assessment of the effectiveness of treatment should therefore include evaluation of patient‐rated measures of quality of life. The primary objective of the study was to determine the feasibility of studying the effect of surgical treatment of skeletal metastases on quality of life. The secondary objective was to provide data that begin to characterize this effect. The characteristics of patients with skeletal metastases are heterogeneous, patient enrollment in the study may be low, high attrition occurs secondary to death, and well accepted health‐status measures (such as the Short Form‐36) may be ineffective at detecting changes in health status: therefore, it is difficult to study these patients. High attrition and adjuvant treatment with radiation or chemotherapy made it impractical to draw firm conclusions about the effect of surgical treatment, but a trend toward improvement in selected health‐status measures for both physical and mental health was noted. Analysis of patient‐rated health‐status scores as predictors of survival indicates that improvement in these scores 6 weeks after surgery is associated with an increase in the length of survival following surgery.
Use of roentgenography and magnetic resonance imaging to predict meniscal geometry determined with a three‐dimensional coordinate digitizing system
Authors: Haut T. L. , Hull M. L. , Howell S. M.
Published: February 2005

To evaluate and improve on the procedures used by a tissue bank in selecting donor menisci for transplantation, this study was designed to fulfill four objectives: (a) define and quantify a set of independent parameters for describing the geometry of the medial and lateral menisci, (b) determine how well the sizing protocol of the tissue bank (i.e., two transverse roentgenographic measurements obtained from the injured knee or six transverse magnetic resonance imaging measurements obtained from the contralateral knee) predicts the four standard transverse parameters of the menisci, (c) determine if including one additional transverse roentgenographic measurement for each compartment improves the ability of roentgenograms to predict transverse meniscal parameters, and (d) determine if five magnetic resonance imaging measurements at three different meniscal cross sections of the contralateral knee predict the 15 standard cross‐sectional parameters of the meniscus in the injured knee. A laser‐based, noncontacting three‐dimensional coordinate digitizing system was used to determine surface coordinates from which menisci were reconstructed in a computer. For each reconstructed meniscus, four parameters in the transverse plane and five cross‐sectional parameters in each of three regions (i.e., anterior, middle, and posterior) were defined, yielding a set of 19 standard parameters to describe the geometry. Through a correlation analysis, these standard parameters were shown to be largely unrelated to one another, thus confirming that the parameters form an independent set describing the three‐dimensional geometry of the menisci. The two roentgenographic measurements were poor predictors of transverse standard meniscal parameters, predicting only one of four standard parameters for the medial meniscus and none of four standard parameters for the lateral meniscus with coefficients of determination greater than on equal to 0.5. Including one additional roentgenographic measurement to the tissue bank protocol increased the number of standard transverse parameters predicted to three of four for the medial meniscus and two of four for the lateral meniscus. Magnetic resonance imaging was better than roentgenography for predicting the three‐dimensional meniscal geometry. The transverse measurements from magnetic resonance imaging predicted three of four standard transverse parameters for the medial meniscus and all four for the lateral meniscus. With the addition of the cross‐sectional measurements by magnetic resonance imaging, seven of 15 standard cross‐sectional parameters were predicted for both the medial and lateral menisci. Assuming that a successful clinical outcome depends on how well an allograft matches the size and shape of the original meniscus, magnetic resonance imaging rather than roentgenography should be used for allograft size‐matching by tissue banks.
Early medial collateral ligament scars have inferior creep behaviour
Authors: Thornton G. M. , Leask G. P. , Shrive N. G. , Frank C. B.
Published: February 2005

Recent evidence suggests that ligaments are subject to repetitive loads in vivo. Hence, the creep behaviour (increase in strain under constant or repetitive stress) of ligament scars is of significance, since healing ligaments may elongate permanently over time. A rabbit medial collateral ligament model was used to assess the creep behaviour of healing ligaments at stresses corresponding to 30% of the scar failure strength at 3 (n = 6), 6 (n = 6), and 14 (n = 5) weeks of healing. The stresses for the creep tests of scars (and contralateral controls) were 2.2, 4.1, and 7.1 MPa for the 3.6, and 14‐week healing intervals, respectively. Normal medial collateral ligaments from comparable rabbits were tested at two of the corresponding stresses: 4.1 (n = 7) and 7.1 (n = 6) MPa. Total creep strain—the cumulative increase in strain resulting from serial cyclic and static creep testing—was independent of the order of testing and was compared between scars and controls. Water contents after testing were also quantified. Water contents before testing were assessed for additional animals: six normal animals and three from each healing interval. At 3 weeks of healing, the total creep strain of medial collateral ligament scars was four times greater than that for contralateral controls tested at the same stress. Although there was improvement from 3 to 14 weeks, the total creep strain of scars remained more than two times greater than that of controls at 14 weeks. Scar water content decreased with healing from elevated initial values, possibly contributing to the marginally improved creep response. Comparisons of this deficiency in scar creep with previously published scar abnormalities in the same model suggest that collagen crosslink density, proteoglycan content, soft‐tissue flaws, and the combined effect of collagen fibre changes may be mechanistic factors involved in scar creep.
Longitudinal characterization of synovial fluid biomarkers in the canine meniscectomy model of osteoarthritis
Authors: Lindhorst E. , Vail T. P. , Guilak F. , Wang H. , Setton L. A. , Vilim V. , Kraus V. B.
Published: February 2005

Damage to the meniscus can lead to posttraumatic osteoarthritis. Early markers of joint injury and tissue disease may be useful in developing and administering clinical treatment. We investigated the effects of total medial meniscectomy on biomarkers measured serially in synovial lavage fluid each month for 3 months. Following meniscectomv in dogs, four biomarkers were evaluated: cartilage oligomeric matrix protein, keratan sulfate epitope (5D4), the 3B3(−) neoepitope of chondroitin‐6‐sulfate, and the 3B3(+) chondroitinasegenerated epitope of chondroitin‐6‐sulfate. Meniscectomy led to statistically significant elevations of all four biomarkers, with levels peaking at 4 weeks. By 12 weeks, the level of the 5D4 epitope returned to the preoperative baseline level whereas that of cartilage oligomeric matrix protein, 3B3(−), and 3B3(+) remained above the baseline. Concentrations of these biomarkers in the knees not operated on did not change significantly from the baseline. The levels of cartilage oligomeric matrix protein and 3B3(−) relative to 3B3(+) remained constant in all knees. In contrast, the level of 5D4 relative to 3B3(+) declined over time in the knee operated on but remained constant in the knee not operated on. These results demonstrate a quantitative change in the molecular components of synovial fluid after meniscectomy, as well as a qualitative change evinced by an alteration in the relative proportions of these epitopes. Extensive analyses showed a strong correlation between serum levels of 3B3(−) from the femoral and cephalic veins; however, serum 3B3(−) was not correlated with synovial fluid 3B3(−). These findings support the hypothesis that the concentrations of select cartilage biomarkers in synovial fluid are altered following meniscectomy and are promising tools for objectively monitoring the induction of osteoarthritis in this model system.
Mechanical compression modulates proliferation of transplanted chondrocytes
Authors: Li Kelvin W. , Falcovitz Yehudit H. , Nagrampa Jennifer P. , Chen Albert C. , Lottman Lisa M. , Shyy John Y‐J. , Sah Robert L.
Published: February 2005

The presence of an appropriate number of reparative cells in an articular cartilage defect is probably necessary for consistent and successful repair. Following the transplantation of chondrocytes into a defect, cell proliferation may modulate local defect cellularity. Transplanted cells can be compressed during cartilage repair as a result of joint‐loading or press‐fitting a graft into a cartilage defect. The objective of this study was to characterize the proliferative response of chondrocytes after attachment to cartilage and application of static compressive stress between cartilaginous surfaces in an ex vivo model. The chondrocytes were isolated from adult bovine cartilage, cultured in high‐density monolayer, resuspended, and then transplanted onto the surface of devitalized cartilage at a density of 250,000 cells/cm2. The total DNA content of transplanted cell layers increased steadily to a plateau by 5 days and represented a 4‐fold increase in cell number during incubation in medium including serum and ascorbate. Over the culture period, the level of DNA synthesis ([3H]thymidine incorporation), on a per cell basis, decreased steadily (88% between days 0 and 6). The application of 24 hours of static compressive stress (0.06‐0.4 MPa) to the adherent cells at 1 and 4 days after transplantation inhibited overall DNA synthesis by 70‐∼87% compared with unloaded controls. After release from load, cell proliferation generally remained at low levels. The marked proliferation of chondrocytes when attached to cartilage without applied load and the inhibition of this proliferation by relatively low‐amplitude static compressive stress may be relevant to the occasional overgrowth of tissue in some chondrocyte transplantation procedures. The dosimetry of these effects suggests that the in vivo mechanical environment may have a marked effect on proliferation of transplanted chondrocytes.
Mechanical modulation of tenascin‐C and collagen‐XII expression during avian synovial joint formation
Authors: Mikic Borjana , Wong Marcy , Chiquet Matthias , Hunziker Ernst B.
Published: February 2005

The objective of this study was to investigate how temporal and spatial patterns of characteristic extracellular matrix molecules are altered in the absence of normal functional skeletal muscle contractions during avian synovial joint development. By using in situ detection of protein and mRNA expression in developing avian feet and femorotibial joints from a wide range of developmental stages, we demonstrate that the morphological abnormalities that result from embryonic immobilization are associated with altered patterns of tenascin‐C and collagen‐XII expression within developing joint structures. As the joints fuse in immobilized embryos, the cells of the presumptive articular surface differentiate from flattened fibroblasts to more rounded chondrocytes and collagens XII and I are no longer detected at sites of complete joint fusion. Although the expression of collagen XII persists at normal levels elsewhere within the immobilized joint, tenascin‐C expression is diminished within the chondroepiphysis, synovium, and tendons, as well as within the remains of the fibrous articular surface. This effect is most notable for the shortest tenascin variant (Tn 190) within the chondroepiphysis and the largest variant (Tn230) within tendons, synovium, and the fibrous surface layer of the joint. This study thus provides in vivo support of previous in vitro work that suggests that tenascin expression is sensitive to external changes in mechanical loading environment. However, these data do not support a similar conclusion for collagen XII during early development.
Femoral structure and stiffness in patients with femoral neck fracture
Authors: Cody Dianna D. , Hou Fu J. , Divine George W. , Fyhrie David P.
Published: February 2005

Bone morphological characteristics may relate to the risk of hip fracture. We applied finite element modeling to radiologic data for two groups of women in vivo to address two questions: (a) Do individuals who have just sustained a femoral neck fracture exhibit reduced three‐dimensional structural stiffness? and (b) Are victims of hip fracture disproportionately more susceptible to loads sustained in a fall than to stance‐type loads? Ten white women (age: 64–76 years) who had just sustained a femoral neck fracture and 18 female volunteers (age: 65–76 years), matched as groups for race, age, and body mass index, were evaluated, From quantitative computed tomography scans, femoral morphometric and volumetric cancellous density measurements were obtained and a finite element model was constructed. Two load conditions were simulated: single‐stance phase and lateral fall. Global stiffness values were determined for each model. The cancellous bone density was significantly lower at the femoral neck and the femoral neck and head diameters were significantly larger in the women in the fracture group than in those in the control group. The stiffness of the proximal femur did not differ significantly between the groups for either load condition. An apparently linear relationship was found for stiffness at stance load compared with stiffness at fall load (r = 0.84, p < 0.001), and slopes did not differ significantly between the groups. Although cancellous density was reduced at the fracture site in patients with femoral neck fractures, this did not result in a reduction in the predicted bone stiffness. Previous studies have established a very strong relationship between the stiffness and strength of bone. Since these modeling methods were thoroughly validated ex vivo, we conclude that although decreased bone density at the femoral neck may predict where fracture initiates, the risk of hip fracture per se may be more strongly dependent on issues such as the risk of falling and fall biomechanics than on the structural characteristics of bone.
Knee pain and joint loading in subjects with osteoarthritis of the knee
Authors: Hurwitz D. E. , Ryals A. R. , Block J. A. , Sharma L. , Schnitzer T. J. , Andriacchi T. P.
Published: February 2005

Although treatments for osteoarthritis of the knee are often directed at relieving pain, pain may cause patients to alter how they perform activities to decrease the loads on the joints. The knee‐adduction moment is a major determinant of the load distribution between the medial and lateral plateaus. Therefore, the interrelationship between pain and the external knee‐adduction moment during walking may be especially important for understanding mechanical factors related to the progression of medial tibiofemoral osteoarthritis. Fifty‐three subjects with symptomatic radiographic evidence of osteoarthritis of the knee were studied. These subjects were a subset of those enrolled in a double‐blind study in which gait analysis and radiographic and clinical evaluations were performed after a 2‐week washout of anti‐inflammatory and analgesic treatment. The subjects then took a nonsteroidal anti‐inflammatory drug, acetaminophen, or placebo for 2 weeks, and the gait and clinical evaluations were repeated. The change in the peak external adduction moment between the two evaluations was inversely correlated with the change in pain (R = 0.48, p < 0.001) and was significantly different between those whose pain increased (n = 7), decreased (n = 18), or remained unchanged (n = 28) (p = 0.009). Those with increased pain had a significant decrease in the peak external adduction (p = 0.005) and flexion moments (p = 0.023). In contrast, the subjects with decreased pain tended to have an increase in the peak external adduction moment (p = 0.095) and had a significant increase in the peak external extension moment (p = 0.017). The subjects whose pain was unchanged had no significant change in the peak external adduction (p = 0.757), flexion (p = 0.234), or extension (p = 0.465) moments. Thus, decreases in pain among patients with medial tibiofemoral osteoarthritis were related to increased loading of the degenerative portion of the joints. Additional long‐term prospective studies are needed to determine whether increased loading during walking actually results in accelerated progression of the disease.
Expression of cartilage oligomeric matrix protein (COMP) by embryonic and adult osteoblasts
Authors: Di Cesare Paul E. , Fang Carrie , Leslie Michael P. , Tulli Hermina , Perris Roberto , Carlson Cathy S.
Published: February 2005

Cartilage oligomeric matrix protein has been implicated as an important component of endochondral ossification because of its direct effects on chondrocytes. The importance of this protein for skeletal development and growth has been recently illustrated by the identification of mutations in cartilage oligomeric protein genes in two types of inherited chondrodysplasias and osteoarthritic phenotypes: multiple epiphyseal dysplasia and pseudoachondroplasia. In the present study, we report the presence of cartilage oligomeric protein in embryonic and adult osteoblasts. A foot from a 21‐week‐old human fetus, subchondral bone obtained from knee replacement surgery in an adult patient, and a limb from a 19‐day‐postcoital mouse embryo were analyzed with immunostaining and in situ hybridization. In the human fetal foot, cartilage oligomeric protein was localized to osteoblasts of the bone collar and at the newly formed bone at the growth plate and bone diaphyses. Immunostaining was performed on the adult subchondral bone and showed positive intra‐cellular staining for cartilage oligomeric protein of the osteoblasts lining the trabecular bone. There was no staining of the osteocytes. Immunostaining of the mouse limb showed the most intense staining for cartilage oligomeric protein in the hypertrophic chondrocytes and in the surrounding osteoblast cells of the developing bone. Cartilage oligomeric protein mRNA and protein were detected in an osteoblast cell line (MG‐63), and cartilage oligomeric protein mRNA was detected from human cancellous bone RNA. These results suggest that the altered structure of cartilage oligomeric protein by the mutations seen in pseudoachondroplasia and multiple epiphyseal dysplasia may have direct effects on osteoblasts, contributing to the pathogenesis of these genetic disorders.
Inhibitory effects of the quinolone antibiotics trovafloxacin, ciprofloxacin, and levofloxacin on osteoblastic cells in vitro
Authors: Holtom Paul D. , Pavkovic Steven A. , Bravos Peter D. , Patzakis Michael J. , Shepherd Lane E. , Frenkel Baruch
Published: February 2005

We studied the inhibitory effects of the fluoroquinolones levofloxacin, ciprofloxacin, and trova‐floxacin on growth and extracellular matrix mineralization in MC3T3‐E1 osteoblast‐like cell cultures. Levo‐floxacin had the least inhibitory effect on cell growth, with a 50% inhibitory concentration of approximately 80 μg/ml at 48 and 72 hours. Ciprofloxacin had an intermediate degree of inhibition, with a 50% inhibitory concentration of 40 μg/ml at 48 and 72 hours. Trovafloxacin exerted a profound inhibitory effect on cell growth, with a 50% inhibitory concentration of 0.5 μg/ml, lower than clinically achievable serum levels. The decreased cell counts with up to 2.5 μg/ml of trovafloxacin and with up to 40 μg/ml of ciprofloxacin were not associated with decreased rates of 5‐bromo‐2′‐deoxyuridine incorporation per cell. Alatrovafloxacin, the L‐alanyl‐l‐alanine prodrug of trovafloxacin, exerted effects on proliferation and 5‐bromo‐2′‐deoxyuridine incorporation similar to those of the parent compound. The quinolones evaluated also inhibited extracellular matrix mineralization by MC3T3‐E1 cells. Treatment of confluent cultures with trovafloxacin, ciprofloxacin, or levofloxacin resulted in strong inhibition of calcium deposition, as determined on day 14 by alizarin red staining and biochemical analysis. The effect was apparent with 2.5‐5 μg/ml of each of the three antibiotics tested and progressively increased to more than a 90% decline in the calcium/protein ratio with 20‐40 μg/ml antibiotic concentration. Further in vivo studies are advocated to evaluate the relevance of the in vitro cytotoxicity reported here to bone healing in orthopaedic patients.
Distribution of chondrocytes containing α‐smooth muscle actin in human articular cartilage
Authors: Kim A. C. , Spector M.
Published: February 2005

Relatively little is known about the contractile behavior of the human articular chondrocyte. Other connective tissue cells are known to express a contractile actin isoform, α‐smooth muscle actin, in response to injury, at selected stages of wound healing, and in certain pathological conditions. This and recent work demonstrating contractile behavior in adult canine articular chondrocytes in vitro prompted the present study of the distribution of α‐smooth muscle actin‐containing chondrocytes in human articular cartilage. Approximately 75% of the chondrocytes in the superficial region of cartilage expressed α‐smooth muscle actin as demonstrated by immunohistochemistry. In contrast, only approximately 10% of the cells in the deep region stained for this contractile actin isoform. There was no correlation of the percentage of α‐smooth muscle actin‐positive cells in either region with Mankin grade or with age. This is the first report of a contractile potential for human articular chondrocytes. The roles of α‐smooth muscle actin in these cells warrant further investigation. The question of whether it is necessary to refer to these cells as myochondrocytes is considered.
Effects of harvest and selected cartilage repair procedures on the physical and biochemical properties of articular cartilage in the canine knee
Authors: Lee C. R. , Grodzinsky A. J. , Hsu H.‐P. , Martin S. D. , Spector M.
Published: February 2005

This study utilizes a canine model to quantify changes in articular cartilage 15–18 weeks after a knee joint is subjected to surgical treatment of isolated chondral defects. Clinical and experimental treatment of articular cartilage defects may include implantation of matrix materials or cells, or both. Three cartilage repair methods were evaluated: microfracture, microfracture and implantation of a type‐II collagen matrix, and implantation of an autologous chondrocyte‐seeded collagen matrix. The properties of articular cartilage in other knee joints subjected to harvest of articular cartilage from the trochlear ridge (to obtain cells for the cell‐seeded procedure) were also evaluated. Physical properties (thickness, equilibrium compressive modulus, dynamic compressive stiffness, and streaming potential) and biochemical composition (hydration, glycosaminoglycan content, and DNA content) of the cartilage from sites distant to the surgical treatment were compared with values measured for site‐matched controls in untreated knee joints. No significant differences were seen in joints subjected to any of the three cartilage repair procedures. However, a number of changes were induced by the harvest operation. The largest changes (displaying up to 3‐fold increases) were seen in dynamic stiffness and streaming potential of patellar groove cartilage from joints subjected to the harvest procedure. Whether the changes reported will lead to osteoarthritic degeneration is unknown, but this study provides evidence that the harvest procedure associated with autologous cell transplantation for treatment of chondral defects may result in changes in the articular cartilage in the joint.
Cellular contribution of bone graft to fusion
Authors: Gould Stephen E. , Rhee John M. , Tay Bobby K‐B. , Otsuka Norman Y. , Bradford David S.
Published: February 2005

Although a number of studies have examined the fate of graft‐derived cells during the process of fusion, there remains no consensus regarding their exact contribution to bone formation within the fusion mass. We developed two chimeric mouse isograft fusion models that allowed us to track the fate of graft cells within the host fusion bed. Cortical/cancellous bone graft (1:1 ratio of pelvic to vertebral body bone) from male mice was placed between (a) the tibia and fibula or (b) the coccygeal spine transverse processes of syngeneic female hosts. Both models were characterized histologically and histochemically. Graft‐derived cells were then identified by fluorescent in situ hybridization for Y‐chromosome sequences present in only the graft (male) cells. When the fusion mass was healing but not yet fused (at 1 and 2 weeks), numerous graft‐derived cells were observed throughout the fusion site. The predominant graft‐derived cell types included chondrocytes, osteoblasts, and fibroblasts. Chondrocytes arose from precursor cells in the graft de novo, as cartilage was not transplanted during the surgical procedure. By the time a mature fusion mass had formed (at 6 weeks), graft‐derived cells persisted as osteocytes within the cortical rim surrounding the fusion mass. These osteocytes likely differentiated from graft‐derived precursors that had directly formed bone, because transplanted osteocytes within cortical bone graft fragments were noted to rarely survive even at 1 and 2 weeks. Collectively, our results demonstrate for the first time that bone graft contributes cells that, in conjunction with host cells, directly form bone within the fusion mass during all phases of fusion rather than just the early phases.
Murine model for skeletal metastases of Ewing's sarcoma
Authors: Scotlandi Katia , Benini Stefania , Manara Maria Cristina , Serra Massimo , Nanni Patrizia , Lollini Pier‐Luigi , Nicoletti Giordano , Landuzzi Lorena , Chano Tokuhiro , Picci Piero , Baldini Nicola
Published: February 2005

Ewing's sarcoma shows a strong tendency to metastasize to the lungs or the skeleton, or both. A peculiar feature of the secondary involvement of bone with this tumor is that it may also appear in the absence of clinically evident lung metastases, both at clinical presentation and during the course of the disease. Although osseous metastases are critically relevant for prognosis, the pathogenesis of this peculiar feature of Ewing's sarcoma is poorly understood, partly due to the lack of appropriate experimental in vivo models. We show that the intravenous injection of TC‐71 Ewing's sarcoma cells into athymic 4–5‐week‐old Crl/nu/nu (CD‐1) BR mice reproducibly colonizes specific sites of the skeleton in addition to the lungs and lymph nodes. The distribution and the morphologic appearance of these experimental bone metastases mimic the pattern of skeletal involvement observed in humans. This experimental model of bone metastasis of Ewing's sarcoma.
Methylprednisolone reduces the early vascular permeability increase in spinal nerve roots induced by epidural nucleus pulposus application
Authors: Byröd Gunnar , Otani Koji , Brisby Helena , Rydevik Björn , Olmarker Kjell
Published: February 2005

Autologous nucleus pulposus is known to have injurious effects on spinal nerve roots when applied epidurally. Both inflammatory and immunological mechanisms have been implicated in this regard. Various proinflammatory substances might be released or activated by nucleus pulposus and might affect the endoneural nerve root vessels. The present study assessed nucleus pulposus‐induced early vascular reactions and the possibility of blocking these reactions with intravenous, high‐dose, methylprednisolone pretreatment. In 25 pigs, the S2 and S3 nerve roots were exposed. In five pigs (control group), retroperitoneal fat was applied epidurally on the nerve roots, and the other 20 pigs had nucleus pulposus applied. This group was subdivided into the treatment group (n = 8), in which the pigs were pretreated with intravenous high‐dose methylprednisolone (30 mg/kg body weight), and the nontreatment group (n = 12), in which the pigs received a corresponding volume of saline solution. After 2 hours, Evans blue labeled albumin was injected intravenously 5 minutes before death. Endoneural extravasation of Evans blue labeled albumin was evaluated with fluorescence microscopy. A marked albumin leakage was found in 67% of the nontreated animals, in 25% of those in the treatment group, and in none of the control animals. These results demonstrate that nucleus pulposus can induce a rapid increase in endoneural vascular permeability in spinal nerve roots after epidural application. This increase can be partially prevented by pretreatment with high‐dose methylprednisolone.
Kinetics and mechanism of the reaction of N‐chlorosuccinimide with I− and OH−
Authors: Agulla B. , Antelo J. M. , Arce F. , Parajó M.
Published: February 2005

In this kinetic study of the reaction between the iodide ion and the N‐chlorosuccinimide, we have found that the reaction is first order in N‐chlorosuccinimide: namely, first order with respect to the iodide ion and first order with respect to the proton concentration. Based on the experimental results, we propose a mechanism consistent in Cl+ transfer from the N‐chlorosuccinimide to the iodide ion. We have found that the reaction presents general acid catalysis with a Brönsted exponent value of 0.10. In addition, given that the N‐chlorocompounds are not stable in aqueous solution, we have carried out a study on the influence of bases in the presence of N‐chlorosuccinimide. We have found that the reaction is first order in hydroxide ion, as well as in the 1,1,1,3,3,3‐hexafluoroisopropanoxide ion and the 2,2,2‐trifluorethoxide ion, which shows that the reaction is general‐base catalyzed. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 243–252, 2005
Synthesis of Large‐Area Three‐Dimensional Polyaniline Nanowire Networks Using a “Soft Template”
Authors: Zhong Wenbin , Deng Jianyuan , Yang Yongsheng , Yang Wantai
Published: February 2005

Summary: Three‐dimensional polyaniline (PANI) nanowire networks were synthesized in high yield using a “soft template” self‐assembled with hexadecyltrimethylammonium bromide and oxalic acid. The PANI nanowire networks had diameters from 35–100 nm depending on synthesis conditions and/or procedures. The networks and the “cross‐linking points” were clearly observed by field‐emission scanning electron microscopy and transmission electron microscopy. A possible mechanism for the formation of three‐dimensional PANI nanowire networks is discussed.

FESEM image of PANI with three‐dimensional nanowire networks.

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FESEM image of PANI with three‐dimensional nanowire networks.
Electroactive Shape‐Memory Polyurethane Composites Incorporating Carbon Nanotubes
Authors: Cho Jae Whan , Kim Jeong Won , Jung Yong Chae , Goo Nam Seo
Published: February 2005

Summary: Electro‐active shape‐memory composites were synthesized using conducting polyurethane (PU) composites and multi‐walled carbon nanotubes (MWNTs). Surface modification of the MWNTs (by acid treatment) improved the mechanical properties of the composites. The modulus and stress at 100% elongation increased with increasing surface‐modified MWNT content, while elongation at break decreased. MWNT surface modification also resulted in a decrease in the electrical conductivity of the composites, however, as the surface modified MWNT content increased the conductivity increased (an order of 10−3 S · cm−1 was obtained in samples with 5 wt.‐% modified‐MWNT content). Electro‐active shape recovery was observed for the surface‐modified MWNT composites with an energy conversion efficiency of 10.4%. Hence, PU‐MWNT composites may prove promising candidates for use as smart actuators.

The electro‐active shape‐recovery behavior of PU‐MWNT composites. The pictured transition occurs within 10 s when a constant voltage of 40 V is applied.

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The electro‐active shape‐recovery behavior of PU‐MWNT composites. The pictured transition occurs within 10 s when a constant voltage of 40 V is applied.
Rubber Powder – A Perspective Filler of Thermoplastics
Authors: Wagenknecht Udo , Steglich Stefanie , Wiessner Sven , Michael Hannes
Published: February 2005

Rubber powder, ground at ambient temperature, was compounded with polypropylene using only 16 L/D of a co‐rotating twin screw extruder. An optimum of extruder configuration and selected process parameters were found for compounds with a rubber filling rate of 50 wt.‐%. Restrictions of a reactive compounding were taken into account. The dispersion of the rubber powder is not a limiting process. A compound containing 70 wt.‐% rubber powder showed to be overfilled.
Levodopa in the treatment of Parkinson's disease: Current controversies
Authors: Gerlach Manfred , Reichmann Heinz , Riederer Peter
Published: February 2005

Companion letters have been published in Movement Disorders: Current Controversies: Levodopa in the Treatment of Parkinson's Disease, by Sharma, Vassallo, and Ross and Reply: Levodopa in the Treatment of Parkinson's Disease, by Olanow, Agid, and Mizuno.
In vitro effects of growth factors on rat germ cell RNA synthesis and their modulation by sertoli cell‐secreted proteins
Authors: Fradin S. , Barbey P. , Drosdowsky M. A.
Published: February 2005

In vitro rat germ cell RNA synthesis is influenced by growth factors. Basic fibroblast growth factor (0.1 to 100 ng/ml) increases [3H]uridine incorporation in round spermatids (RS) but not in pachytene spermatocytes (PS); this effect is potentiated by insulin (10 μg/ml) and blocked in the presence of Sertoli cell‐secreted proteins (SCSP). Somatomedin C (0.1 to 100 ng/ml) exhibits a similar effect when used alone without an influence by SCSP. Transforming growth factor β (0.1 to 10 ng/ml) acts on both cell types, but SCSP amplify this effect only in PS. These data suggest that growth factors synthesized in situ may play a role in the germ cell development and that their effects are moduiated by SCSP.
Detection of Y‐bearing spermatozoa by DNA‐DNA in situ hybridisation
Authors: West John D. , West Katrine M. , Aitken R. John
Published: February 2005

In situ hybridisation of a Y chromosome‐specific DNA probe to preparations of decondensed spermatozoa revealed approximately 46.7% labelled spermatozoa among 3,900 scored. This is not significantly different from the 50% expected if only the Y chromosome‐bearing spermatozoa are hybridised. Control hybridisations of Escherichia coli DNA and salmon testis DNA to decondensed sperm produced no significant labelling, whereas more than 99% of the spermatozoa were heavily labelled after hybridisation to total human DNA. These controls indicate that the methodology described in this paper renders the chromatin accessible for hybridisation and that the 50% hybridisation observed with the Y chromosome DNA probe was specific. In situ hybridisation with the Y probe therefore identifies the Y‐bearing spermatozoa, and the protocol described should prove useful in evaluating methods of separating Y‐bearing and X‐bearing spermatozoa.
Influence of single amino acids on the development of hamster one‐cell embryos in vitro
Authors: Bavister Barry D. , Arlotto Theresa
Published: February 2005

One‐cell hamster embryos placed in culture have always shown a complete block to development at the two‐cell stage. In a preliminary study using a chemically defined culture medium containing 20 amino acids (HECM‐1), many one‐cell embryos were able to escape the “two‐cell block” and develop to the four‐cell stage. Use of a simpler formulation containing only the amino acids hypotaurine and glutamine revealed marked inhibitory and stimulatory effects of adding the other amino acids. In the first experiment, 19 amino acids were separately examined for effects on one‐cell embryo development. Six amino acids (phenylalanine, valine, isoleucine, tyrosine, tryptophan, and arginine) inhibited embryo development (reduced mean cell number; MCN), and three others (glycine, cystine, and lysine) stimulated development (increased MCN), compared with basic medium containing only glutamine and hypotaurine (low control). When the responses with the six inhibitory amino acids were totalled, only 3 of 185 (2%) one‐cell embryos reached the six‐or seven‐cell stage compared to a total of 15 of 76 (20%) embryos that developed to these stages using the three stimulatory amino acids. When tested together in a second experiment, the six inhibitory amino acids significantly reduced the MCN, from 4.28 ± 0.44 (low control) to 3.71 ± 0.55. In this group, 17 of 117 (15%) of one‐cell embryos reached more than four‐cell and only 4 of 117 (3%) reached six‐ or 7‐cell stages, compared with 39 of 117 (33%) and 12 of 117 (10%), respectively, for the basal medium group. The stimulatory (glycine, cystine, lysine) and “neutral” (cysteine‐SH, proline, serine, threonine, histidine, alanine, hydroxyproline, leucine, aspartic acid, methionine) groups did not significantly alter the MCN, but both supported development of a substantial proportion of one‐cell embryos to more than four‐cell stages (38% and 48%, respectively, of 126 embryos in each group), and to six‐ or seven‐cell stages (20% and 29%, respectively, for the stimulatory and neutral groups). In these two groups, a few one‐cell embryos even reached the eight‐cell or blastocyst stages. This study shows that the type of amino acid in the culture medium has a profound influence on the number of cleavage divisions undergone by one‐cell hamster embryos and suggests that, at least in vitro, amino acids may play an important regulatory role in early preimplantation development in this species.