bluuebunny/crossref_metadata_2025 huggingface dataset:
mRNA expression of interleukins, phospholipase A2, and nitric oxide synthase in the nerve root and dorsal root ganglion induced by autologous nucleus pulposus in the rat
Authors: Kawakami Mamoru , Matsumoto Takuji , Kuribayashi Koichi , Tamaki Tetsuya
Published: February 2005

The purpose of this study was to examine whether mRNA of interleukin‐1β, interleukin‐6, phospholipase A2, and nitric oxide synthase was expressed in the nerve root and dorsal root ganglion of an animal model in which exposure to the nucleus pulposus induced mechanical hyperalgesia, a pain‐related behavior. Autologous nucleus pulposus obtained from coccygeal discs was relocated on the L4 and L5 lumbar nerve roots after partial laminectomy. The reflex response to noxious mechanical stimuli to the hindpaw was measured preoperatively and to 4 weeks postoperatively. With a reverse transcription‐polymerase chain reaction technique, expression of interleukin‐1β, interleukin‐6, phospholipase A2, and inducible nitric oxide synthase genes in the nerve root and dorsal root ganglion was observed at 1, 2, and 4 weeks postoperatively. Mechanical hyperalgesia was observed from 3 days to 2 weeks postoperatively. The expression of interleukin‐1β, phospholipase A2, and inducible nitric oxide synthase mRNAs increased after only 1 week. This increase was related to mechanical hyperalgesia. Expression of interleukin‐6 was detected in the neural tissue over time. It is possible that interleukin‐1β, phospholipase A2, and inducible nitric oxide in the nerve root or dorsal root ganglion, or in both, produce sciatic pain in the early stage of herniation of the lumbar disc.
Contamination of the medullary canal following pin‐tract infection
Authors: Clasper J. C. , Parker S. J. , Simpson A. H. R. W. , Watkins P. E.
Published: February 2005

We developed an ovine model of an external‐fixator pin‐tract infection. With use of a novel method of tissue sampling, infection of the medullary canal was confirmed in all (10 of 10) external‐fixator pins that were contaminated with Staphylococcus aureus after they were inserted. In addition, all (five of five) adjacent, uncontaminated pins became infected. We demonstrated that pin‐tract infection can be difficult to diagnose clinically, despite gross infection of the tract, and that bacteria can spread within the medulla. Three of the infected pins (20%) did not appear clinically infected, were not loose, and were normal on radiographs after 1 week. Staphylococcus aureus was isolated from the medulla around all 15 pin tracts, and nine other organisms were isolated from the tracts. Despite the presence of infection, the majority of the pins remained well fixed in the bone after 2 weeks.
Drug‐induced apoptosis in osteosarcoma cell lines is mediated by caspase activation independent of CD95‐receptor/ligand interaction
Authors: Fellenberg J. , Mau H. , Nedel S. , Ewerbeck V. , Debatin K‐M.
Published: February 2005

Osteosarcoma is one of the most common primary malignant tumors of bone. Treatment of this tumor with systemic chemotherapy dramatically improves the prognosis, although the molecular mechanisms involved in the drug action are poorly understood. In chemosensitive leukaemic T cells and certain solid tumors. cytotoxic drugs mediate the induction of apoptosis by activation of the CD95/APO‐1/Fas system. Triggering of the corresponding signaling pathway may involve CD95‐receptor/ligand interaction, activation of caspases, or alterations in mitochondrial function. The purpose of our study was to determine if similar mechanisms are involved in the chemosensitivity of osteosarcomas. We found that cytotoxic drugs induce characteristic biochemical and morphological alterations related to apoptosis in osteosarcoma cell lines, including activation of caspases and disturbance of mitochondrial function. However, drug treatment did not result in activation of CD95‐receptor or CD95‐ligand mRNA. In addition, drug‐induced apoptosis was blocked by caspase inhibitors but not by inhibition of CD95‐ligand action, indicating a CD95‐receptor/ligand‐independent mechanism in osteosarcoma cell lines.
Cellular responses of embryonic hyaline cartilage to experimental wounding in vitro
Authors: Walker E. A. , Verner A. , Flannery C. R. , Archer C. W.
Published: February 2005

It is well established that the reparative potential of many tissues is greatest during embryonic development. Despite the extensive literature documenting repair in nonembryonic cartilage models, there is no comparable wealth of experience relating to embryonic cartilage repair. With the embryonic chick sternum as a model of hyaline cartilage, this paper accounts cellular responses and alterations in extracellulat matrix composition in response to experimental wounding in vitro. Creation of an experimental lesion induced a rapid (<20 minutes) apoptotic response in chondrocytes adjacent to the lesion edge; the presence of perichondrium delayed this response. Alterations in the extracellular matrix included immediate mechanical damage to type‐II collagen fibrils and an increase in the expression of chondroitin‐4 sulphate next to the lesion. Creation of the lesion induced an increased proliferative response in chondrocytes behind the zone of apoptosis and the expression of α5 and α6 integrin subunits.
Comparison of three methods of gluteal muscle attachment to an allograft/endoprosthetic composite in a canine model
Authors: Pluhar G. Elizabeth , Heiner John P. , Manley Paul A. , Bogdanske John J. , Vanderby Ray , Markel Mark D.
Published: February 2005

This study used radiography, gait analysis, gluteal muscle mass, mechanical testing, and qualitative histology to compare three methods of gluteal muscle attachment to an allograft/endoprosthetic composite of the proximal 25% of the femur in anin vivocanine model. The three methods of gluteal muscle attachment were identical to those used clinically in human patients for hip revision and proximal femoral limb salvage: the host gluteal tendon sutured to the allograft tendon (tendon group), the host greater trochanter with intact gluteal tendons secured to the allograft with a cable‐grip system (grip group), and periosteally vascularized proximal femoral bone onlay with intact tendons wrapped around the allograft (wrap group). On the basis of radiographs taken every 2 months, the tendon group had more graft fractures than did the grip or wrap group. Radiographic union of the graft‐host bone junction occurred more rapidly and there was less graft resorption in the wrap group than in the other two groups. In all dogs, peak vertical ground‐reaction forces in the treated limb decreased immediately after surgery and then slowly increased over the length of the study. The dogs in the wrap group regained normal weight‐bearing on the treated limb more quickly than did those in the other groups. The constructs in the tendon group were weaker and less stiff immediately after surgery than were those in the other groups or in intact controls. Histologic analysis confirmed that the wrap technique resulted in complete union of the host bone‐allograft junction more often than did the other techniques. The wrap method had the best functional outcome after 9 months when an allograft/endoprosthetic composite was used during total hip arthroplasty in this canine model.
Collagen crosslinked N‐telopeptides as markers for evaluating particulate osteolysis: A preliminary study
Authors: Antoniou John , Huk Olga , Zukor David , Eyre David , Alini Mauro
Published: February 2005

The purpose of this study was to determine whether a marker of bone resorption could be used noninvasively to diagnose and assess treatment of periprosthetic osteolysis. The crosslinked N‐telopeptide marker of osteoclast‐mediated bone resorption potentially has the sensitivity to detect periprosthetic osteolysis. Second‐morning urine specimens were obtained from (a) seven age‐matched controls, (b) eight patients who had a hip arthroplasty, hybrid implants at least 1 year after surgery, and no osteolysis, (c) 11 patients who had a hip arthroplasty and osteolysis, and (d) 10 patients who had a hip arthroplasty and with osteolysis before and after 6 weeks of oral Fosamax (alendronate) treatment. The Fosamax treatment consisted of one 10‐mg dose per day for 6 weeks. Men and young women (less than 40 years old) were chosen for this study to avoid bone resorption enhanced after menopause as a possible confounder. An enzyme‐linked immunosorbent assay technique for quantifying crosslinked N‐telopeptides of type‐I collagen was performed on all specimens. The patients with osteolysis had significantly elevated levels of N‐telopeptide compared with the implant control group. In addition, levels of N‐telopeptide were significantly lowered after Fosamax treatment. These findings indicate that a systemic bone‐resorption marker (N‐telopeptide) can be used to evaluate local particulate‐induced osteolysis and its treatment. The study also provides clinical evidence that osteolysis is associated with increased osteoclast‐mediated bone resorption and that this locally induced bone resorption can be suppressed by certain bisphosphonates (Fosamax). These insights have potential value in the understanding and clinical management of aseptic loosening.
Effect of compressive loading on chondrocyte differentiation in agarose cultures of chick limb‐bud cells
Authors: Elder S. H. , Kimura J. H. , Soslowsky L. J. , Lavagnino M. , Goldstein S. A.
Published: February 2005

It is well established that mechanical loading is important to homeostasis of cartilage tissue, and growing evidence suggests that it influences cartilage differentiation as well. Whereas the effect of mechanical forces on chondrocyte biosynthesis and gene expression has been vigorously investigated, the effect of the mechanical environment on chondrocyte differentiation has received little attention. The long‐term objective of this research is to investigate the regulatory role of mechanical loading in cell differentiation. The goal of this study was to determine if mechanical compression could modulate chondrocyte differentiation in vitro. Stage 23/24 chick limb‐bud cells, embedded in agarose gel, were subjected to either static (constant 4.5‐k Pa stress) or cyclic (9.0‐kPa peak stress at 0.33 Hz) loading in unconfined compression during the initial phase of commitment to a phenotypic lineage. Compared with nonloaded controls, cyclic compressive loading roughly doubled the number of cartilage nodules and the amount of sulfate incorporation on day 8, whereas static compression had little effect on these two measures. Neither compression protocol significantly affected overall cell viability or the proliferation of cells within nodules. Since limb‐bud mesenchymal cells were seeded directly into agarose, an assessment of cartilage nodules in the agarose reflects the proportion of the original cells that had given rise to chondrocytes. Thus, the results indicate that about twice as many mesenchymal cells were induced to enter the chondrogenic pathway by cyclic mechanical compression. The coincidence of the increase in sulfate incorporation and nodule density indicates that the primary effect of mechanical compression on mesenchymal cells was on cellular differentiation and not on their subsequent metabolism. Further studies are needed to identify the primary chondrogenic signal associated with cyclic compressive loading and to determine the mechanism by which it influences commitment to or progression through the chondrogenic lineage, or both.
Assessment of resorbable bioactive material for grafting of critical‐size cancellous defects
Authors: Wheeler D. L. , Eschbach E. J. , Hoellrich R. G. , Montfort M. J. , Chamberland D. L.
Published: February 2005

Bioactive glasses form a surface apatite layer in vivo that enhances the formation and attachment of bone. Sol‐gel Bioglass graft material provides greater nanoscale porosity than bioactive glass (on the order of 50–200 Å), greater particle surface area, and improved resorbability, while maintaining bioactivity. This study histologically and biomechanically evaluated, in a rabbit model, bone formed within critical‐sized distal femoral cancellous bone defects filled with 45S5 Bioglass particulates, 77S sol‐gel Bioglass, or 58S sol‐gel Bioglass and compared the bone in these defects with normal, intact, untreated cancellous bone and with unfilled defects at 4, 8, and 12 weeks. All grafted defects had more bone within the area than did unfilled controls (p < 0.05). The percentage of bone within the defect was significantly greater for the 45S5 material than for the 58S or 77S material at 4 and 8 weeks (p < 0.05), yet by 12 weeks equivalent amounts of bone were observed for all materials. By 12 weeks, all grafted defects were equivalent to the normal untreated bone. The resorption of 77S and 58S particles was significantly greater than that of 45S5 particles (p < 0.05). Mechanically, the grafted defects had compressive stiffness equivalent to that of normal bone at 4 and 8 weeks. At 12 weeks, 45S5‐grafted defects had significantly greater stiffness (p < 0.05). At 8 and 12 weeks, all grafted defects had significantly greater stifness than unfilled control defects (p < 0.05). In general, the 45S5‐filled defects exhibited greater early bone ingrowth than did those filled with 58S or 77S. However, by 12 weeks, the bone ingrowth in each defect was equivalent to each other and to normal bone. The 58S and 77S materials resorbed faster than the 45S5 materials. Mechanically, the compressive characteristics of all grafted defects were equivalent or greater than those of normal bone at all time points.
Relationship between quadriceps strength and rate of loading during gait in women
Authors: Mikesky Alan E. , Meyer Adele , Thompson Kerry L.
Published: February 2005

One function of skeletal muscle is to serve as the body's shock absorbers and thus dampen rates of loading during activity. The aim of this cross‐sectional study was to determine the significance of muscle strength on rates of loading during gait. Thirty‐seven women (mean age: 34.5 ± 8.2 years) were solicited by advertisement and placed into one of two groups—strength‐trained or sedentary—on the basis of training history. They walked (10 trials) over a 10‐m walkway at a controlled speed of 1.22–1.35 m/s while the rate of loading was sampled with a 1.000‐Hz force platform. Quadriceps and hamstring strength was measured at 90%/s with an isokinetic dynamometer. Statistical analyses (p <0.05) included descriptive statistics and unpaired / tests for comparison between groups. The women in the sedentary group weighed more and had significantly less concentric and eccentric strength of the quadriceps and hamstrings relative to body weight than did those in the strength‐trained group. In addition, they demonstrated significantly higher rates of loading (2.21 ± 0.15 compared with 1.75 ± 0.08%wt/ms) than those in the strength‐trained group.
Characterization of hamstring reflexes during anterior cruciate ligament disruption: In vivo results from a goat model
Authors: Fujita Ikuo , Nishikawa Tetsuo , Kambic Helen E. , Andrish Jack T. , Grabiner Mark D.
Published: February 2005

The existence of an anterior cruciate ligament‐hamstring reflex arc, the extent to which these reflexes can protect the knee, and the extent to which they are affected by rupture of the anterior cruciate ligament remain controversial. We evaluated the temporal components of the anterior cruciate ligament‐hamstring synergy by simulating an injury to the ligament in a goat model. Reflexive hamstring activation in anesthetized goats was evaluated when the anterior cruciate ligament was loaded with static subfailure, dynamic subfailure, and dynamic failure loads. Reflexive hamstring activation was not found in response to static subfailure loading but was observed in response to dynamic subfailure and failure loading. The latency of the reflex evoked by dynamic failure loading was shorter than that evoked by dynamic subfailure loading. The findings suggest that the extent to which the hamstring reflexes can protect the knee may be bounded by the ability of these muscles to generate force rapidly and the amplitude and time‐course of the loads applied to the knee joint. The present data present a framework for further investigation of the contribution of anterior cruciate ligament‐hamstring reflexes to the stability of the knee joint under high loads and loading rates.
Assessment of elbow joint kinematics in passive motion by electromagnetic motion tracking
Authors: Bottlang M. , Madey S. M. , Steyers C. M. , Marsh J. L. , Brown T. D.
Published: February 2005

This research provides a detailed analysis of the kinematics of passive elbow motion. It quantifies how closely humeroulnar kinematics approximates rotation around a fixed axis. The results are clinically relevant for emerging treatment modalities that impose an artificial hinge to the elbow joint, such as total elbow arthroplasty and articulated external fixation. In a cadaveric study of seven specimens, we quantified ulnar rotation around the humerus in terms of instantaneous screw displacement axes calculated from electromagnetic motion‐tracking source data. This methodology enabled description of the complex excursion of the elbow axis in terms of translation and orientation changes of the screw displacement axes over the range of motion. Furthermore, we analyzed the envelope of joint laxity for elbow motion under applied small varus and valgus moments. In addition, radiographic landmarks of clinical utility for axis location were evaluated by visualizing the elbow's radiographic appearance when viewed from along the calculated best‐fit (average) rotation axis. Over the normal range of elbow motion, the screw displacement axis varied 2.6–5.7° in orientation and 1.4–2.0 mm in translation. All instantaneous rotation axes nearly intersected on the medial facet of the trochlea. The breadth of the envelope of varus‐valgus joint laxity was greatest within the initial 40° of flexion and decreased by a factor of approximately two for flexion angles exceeding 100°.
Time‐dependent increases in type‐III collagen gene expression in medial collateral ligament fibroblasts under cyclic strains
Authors: Hsieh Adam H. , Tsai Cliff M‐H. , Ma Qing‐Jun , Lin Tong , Banes Albert J. , Villarreal Francisco J. , Akeson Wayne H. , Paul Sung K‐L.
Published: February 2005

Numerous studies have demonstrated the capacity of mechanical strains to modulate cell behavior through several different signaling pathways. Understanding the response of ligament fibroblasts to mechanically induced strains may provide useful knowledge for treating ligament injury and improving rehabilitation regimens. Biomechanical studies that quantify strains in the anterior cruciate and medial collateral ligaments have shown that these ligaments are subjected to 4–5% strains during normal activities and can be strained to 7.7% during external application of loads to the knee joint. The objective of this study was to characterize the expression of types I and III collagen in fibroblast monolayers of anterior cruciate and medial collateral ligaments subjected to equibiaxial strains on flexible growth surfaces (0.05 and 0.075 strains) by quantifying levels of mRNA encoding these two proteins. Both cyclic strain magnitudes were studied under a frequency of 1 Hz. The results indicated marked differences in responses to strain regimens not only between types I and III collagen mRNA expression within each cell type but also in patterns of expression between anterior cruciate and medial collateral ligament cells. Whereas anterior cruciate ligament fibroblasts responded to cyclic strains by expression of higher levels of type‐I collagen message with almost no significant increases in type‐III collagen, medial collateral ligament fibroblasts exhibited statistically significant increases in type‐III collagen mRNA at all time points atter initiation of strain with almost no significant increases in type‐I collagen. Furthermore, differences in responses by fibroblasts from the two ligaments were detected between the two strain magnitudes. In particular, 0.075 strains induced a time‐dependent increase in type‐III collagen mRNA levels in medial collateral ligament fibroblasts whereas 0.05 strains did not. The strain‐induced changes in gene expression of these two collagens may have implications for the healing processes in ligament tissue. The differences may explain, in part, the healing differential between the anterior cruciate and medial collateral ligaments in vivo.
Mechanical compression of the lumbar nerve root alters pain‐related behaviors induced by the nucleus pulposus in the rat
Authors: Kawakami Mamoru , Tamaki Tetsuya , Hayashi Nobuhiro , Hashizume Hiroshi , Matsumoto Takuji , Minamide Akihito , Kihira Tameko
Published: February 2005

The purpose of this study was to refine a method of nerve‐root injury in the rat to produce hyperalgesia, a pain‐related behavior, and to determine if there were any relationships between the histological extent of nerve‐root injury and the magnitude of hyperalgesia. Three methods were used to produce hyperalgesia: irritation of a nerve root by ectopic nucleus pulposus, silk loop alone, or both silk loop and ectopic nucleus pulposus. Autologous nucleus pulposus obtained from coccygeal intervertebral discs was relocated on the lumbar nerve roots after laminectomy. Two loops of 4‐0 silk were placed around the exposed nerve roots. Hyperalgesia was measured preoperatively and postoperatively. The distribution of myelinated axons in the dorsal nerve roots was evaluated histologically. Mechanical hyperalgesia was detected in rats in which autologous nucleus pulposus was applied to the nerve root but not in those in which silk loops were used. Silk loops around the nerve root resulted in thermal hyperalgesia only in rats in which autologous nucleus pulposus was applied to the nerve root. Fewer large myelinated fibers were seen in the rats in which silk loops were used. Although a silk loop around the nerve root was not sufficient to produce hyperalgesia, supplemental application of autologous nucleus pulposus to the nerve root produced thermal hyperalgesia. It is possible that mechanical constriction of the nerve root alters the pain‐related behavior elicited by chemical factors from the nucleus pulposus.
Evaluation of recombinant human bone morphogenetic protein‐2 as a bone‐graft substitute in a canine segmental defect model
Authors: Sciadini Marcus F. , Johnson Kenneth D.
Published: February 2005

A study was performed in dogs to evaluate the dose‐response characteristics and effectiveness of recombinant human bone morphogenetic protein‐2 with a collagen sponge carrier in a segmental defect model. Twenty‐seven dogs underwent bilateral radial osteotomies with creation of a 2.5‐cm diaphyseal defect. All received autogenous cancellous bone graft in one defect and a collagen implant in the other. These implants contained recombinant human bone morphogenetic protein‐2 at the following doses: group 1 at 0 μg (three dogs, 0 μg/ml total implant volume), group 2 at 150 μg (three dogs, 50 μg/ml), group 3 at 600 μg (three dogs, 200 μg/ml), group 4 at 2,400 μg (three dogs, 800 μg/ml), group 5 at 0 μg (five dogs, 0 μg/ml), group 6 at 150 μg (five dogs, 200 μg/ml), and group 7 at 600 μg (five dogs, 50 μg/ml). The defects were stabilized with external fixators. The dogs in group 1–4 were killed at 12 weeks postoperatively, and those in groups 5–7 were killed at 24 weeks postoperatively except for one dog in group 7, which was killed at 48 weeks. Evaluation included monthly radiographs, biomechanical testing, and nondemineralized histology. All 27 radii with autogenous cancellous bone graft and all 19 implants treated with recombinant human bone morphogenetic protein‐2 achieved radiographic and histologic union and gross stability. The eight radii treated with collagen carrier alone went on to radiographic and histologic nonunion and were grossly unstable at death. A dose‐dependent occurrence of cyst‐like bone voids was noted radiographically and histologically. Biomechanical performance tended to be better at the lowest dose studied at 12 weeks, and all three doses performed better than the placebo (p < 0.05) at 12 and 24 weeks. By 24 weeks, radiolucent areas corresponding to histologic bone voids persisted radiographically, although there was evidence of early bone remodeling. This remodeling progressed to 48 weeks in the single animal followed to this time point, although bone voids remained. These radiologic findings were confirmed histologically. Recombinant human bone morphogenetic protein‐2 in a collagen sponge carrier has significant osteoinductive activity in this canine segmental defect model. A dose‐response relationship is evident, with heterotopic bone and cyst‐like void formation at higher doses and a minimum effective dose of 0‐150 μg. At 12 and 24 weeks postoperatively, biomechanical parameters achieved by defects treated with recombinant human bone morphogenetic protein‐2 were comparable with those of autograft controls and were significantly stronger than those of the placebo (p < 0.05).
Experimental model for allograft incorporation and allograft fracture repair
Authors: Lee Francis Young‐In , Hazan Eric J. , Gebhardt Mark C. , Mankin Henry J.
Published: February 2005

This study describes a rat model of allograft osteotomy healing. An intercalary skeletal defect was created in adult Lewis rats by resecting a 2‐cm segment of the femur in the diaphysis, including the periosteum and the cuff of muscle layers. The skeletal defects were replaced with fresh‐frozen devascularized intercalary allografts from Sprague‐Dawley rats. A transverse osteotomy was made in the middle of the allograft. The osteolomized segments were stabilized with an intramedullary threaded Kirschner wire, which allowed immediate ambulation. Radiographic and histological examination at 4 and 8 weeks revealed a charactcristic healing process at three different interfaces. Radiographically, the distal metaphyseal host‐donor junction healed faster than the proximal diaphyscal host‐donor interface. The osteotomy site did not have evidence of an intramembranous or endochondral repair process. This model can serve as a baseline for assessing allograft incorporation and fracture repair.
Sequential labelling of microdamage in bone using chelating agents
Authors: Lee T. C. , Arthur T. L. , Gibson L. J. , Hayes W. C.
Published: February 2005

Basic fuchsin labels microcracks, but a series of stains is required to differentiate between preexisting and test‐induced microcracks and to label their growth in vitro. Basic fuchsin and five chelating agents—alizarin complexone, calcein, calcein blue, oxytetracycline, and xylenol orange—were randomly assigned to label microcracks in sequential rib sections from 10 donors. The density, length, and location of the microcracks did not differ significantly between he six stains, suggesting that each was equally effective in detecting microcracks. Paired specimens of trabecular bone were machined from bovine tibiae, stained with oxytetracycline, and fatigued in compression. One specimen from each pair was then stained with xylenol orange. Preexisting microdamage was stained with oxytetracycline, propagating microcracks with both stains and new, test‐initiated damage with xylenol orange. Chelating agents are site‐specific markers of the initiation and growth of microcracks.
Localization of dominantly inherited isolated triphalangeal thumb to chromosomal region 7q36
Authors: Dobbs Matthew B. , Dietz Frederick R. , Gurnett Christina A. , Morcuende Jose A. , Steyers Curtis M. , Murray Jeffrey C.
Published: February 2005

Triphalangeal thumb is an autosomal dominantly inherited form of abnormal preaxial skeletal development. In most families, however, the triphalangeal thumb phenotype coexists with a spectrum of limb deformities, including polydactyly and syndactyly. We describe two Iowa kindreds with triphalangeal thumb. In one family, with nine affected members, triphalangeal thumb was the only manifestation of limb deformity. We performed linkage analysis on both pedigrees, demonstrating a maximum LOD score of 6.23 with marker D7S559 on chromosome 7q36. This corresponds to a previous study of a candidate region of 450 kb in which data from several families with preaxial polydactyly were employed. Further analysis of the unique family with isolated triphalangeal thumb in the current study may demonstrate allelic variability of the gene involved in these disorders.
Inhibition of caspase‐3‐like activity prevents apoptosis while retaining functionality of human chondrocytes in vitro
Authors: Nuttall Mark E. , Nadeau Daniel P. , Fisher Paul W. , Wang Feilan , Keller Paul M. , Dewolf Walter E. , Goldring Mary B. , Badger Alison M. , Lee Dennis , Levy Mark A. , Gowen Maxine , Lark Michael W.
Published: February 2005

Apoptosis was induced in a human chondrocyte cell line, T/C 28a4, by treatment with various stimuli, including camptothecin, tumor necrosis factor‐α, staurosporine, okadaic acid, and reduced serum conditions. All stimuli induced a cytosolic DEVDase activity, coincident with apoptosis. Caspase activities in the lysates were characterized and quantitated with peptide cleavage profiles. To confirm that the results were not related to the immortalized nature of the cell line, primary human chondrocytes also were shown to undergo apoptosis under similar conditions, which resulted in increased cytosolic DEVDase activity. There was little or no caspase‐1 (interleukin‐1β‐converting enzyme) or caspase‐8‐like activity in the apoptotic cells. In all cases, the irreversible nonselective caspase inhibitor, Z‐VAD‐FMK, and the caspase‐3‐selective inhibitor, Ac‐DMQD‐CHO, inhibited DEVDase activity and apoptosis, whereas the caspase‐1‐selective inhibitor, Ac‐YVAD‐CHO, had no effect. Human chondrocytes were stably and transiently transfected with a type‐II collagen gene (COL2A1) regulatory sequence driving a luciferase reporter as a specific marker of chondrocyte gene expression. Treatment of the cells with camptothecin or tumor necrosis factor‐α plus cycloheximide significantly inhibited COL2A1 transcriptional activity. Significantly, cotreatment with Z‐VAD‐FMK or Ac‐DMQD‐CHO maintained COL2A1‐reporter gene activity, indicating that the prevention of apoptosis by caspase‐3 inhibition was sufficient to maintain cell functionality as assessed by the retention of type‐II collagen promoter activity.
Alterations in cartilage type‐ii procollagen and aggrecan contents in synovial fluid in equine osteochondrosis
Authors: Laverty S. , Ionescu M. , Marcoux M. , Bouré L. , Doizé B. , Poole A. R.
Published: February 2005

The etiology and pathophysiology of osteochondrosis remain poorly understood because it is difficult to obtain material from lesions in the early stage of this disease and because there is no satisfactory experimental animal model. We wished to determine whether there are changes in articular cartilage turnover in equine osteochondrosis, which closely resembles the human disease, by assaying cartilage matrix molecules in synovial fluids. We used immunoassays that measure a keratan sulfate epitope and the epitope 846 on the cartilage proteoglycan aggrecan and the C‐propeptide of cartilage type‐II procollagen, which is released following the synthesis of this molecule, to analyse synovial fluids from equine tarsocrural joints with and without osteochondrosis. In young horses with osteochondrosis, there was a significant increase of C‐propeptide of type‐II procollagen accompanied by a decrease in the 846 and keratan sulfate epitopes. The results identify differential alterations in aggrecan and type‐II collagen turnover in the cartilage matrix in young animals with osteochondrosis that may contribute to the pathological degeneration of articular cartilage in this disease.
Age, gender, and bone lamellae elastic moduli
Authors: Hoffler C. E. , Moore K. E. , Kozloff K. , Zysset P. K. , Goldstein S. A.
Published: February 2005

To enhance preventative and therapeutic strategies for metabolic bone diseases and bone fragility disorders, we began to explore the physical properties of bone tissue at the cellular level. Proximal femurs were harvested from 27 cadavera (16 male and 11 female) for in vitro measurement of the mechanical properties. We measured the variations in lamellar‐level elastic modulus and hardness in human bone as a function of age and gender to identify microstructural properties responsible for age and gender‐related reductions in the mechanical integrity. The lateral femoral necks were examined, and age, gender, height, body mass, and body mass index were not found to correlate with lamellar‐level elastic modulus or hardness. This result was consistent for osteonal, interstitial, and trabecular tissue. These data suggest that increased bone mass maintenance, known to occur in heavier individuals, is not accompanied by increases in the lamellar‐level elastic modulus or hardness. The independence of elastic modulus and hardness from age and gender suggests that age and gender‐related decreases in mechanical integrity do not involve alterations in elastic modulus or hard ness of the extracellular matrix. Lamellar‐level ultimate, fatigue, and fracture toughness properties should also be investigated. Other factors, such as tissue mass and organization, may also contribute to age and gender‐related decreases in the mechanical integrity.
Metabolic activity of a new atrophic nonunion model in rabbits
Authors: Brownlow H. C. , Simpson A. H. R. W.
Published: February 2005

The aetiology of atrophic nonunions is not well understood; they are often thought to be nonreactive and metabolically inactive. Investigation of their biological processes is hampered by the lack of a useful animal model. Current models involve either wide segmental excision of the diaphysis or interposition of Silastic to impede the normal healing processes, neither of which resembles the clinical situation. We therefore aimed to establish a model of atrophic nonunion that more closely resembles the clinical situation and to use this model to evaluate the metabolic activity of the gap tissue of the nonunion. A simple and reliable model of atrophic nonunion has been developed in rabbits. It more closely represents the clinical situation by avoiding large segmental excisions and the interposition of foreign materials. Clinical, radiological, and histological data support the diagnosis of atrophic nonunion in the model. The concentration of adenosine triphosphate in the gap tissue of the nonunion served as a marker of metabolic activity. The gap tissue of established atrophic nonunions had a significantly higher concentration of adenosine triphosphate than did the control specimens. In this model, the gap tissue is metabolically active; therefore, under certain conditions, it may be possible to induce union if the correct stimulus is provided.
Cartilage repair with autogenic perichondrium cell/polylactic acid grafts: A two‐year study in rabbits
Authors: Dounchis Jon S. , Coutts Richard D. , Amiel David
Published: February 2005

The repair of articular cartilage injuries remains a challenge. In this 2‐year study, osteochondral defects in the femoral condyles of five rabbits were repaired with an autogenic perichondrium cell/polylactic acid grafts and compared with a contralateral control in which the defect remained empty. The rabbits in the group with the grafts had a higher percentage of biologically acceptable repairs (100%) than did those in the control group (80%). According to the histologic and histomorphometric analyses, the grafts augmented the intrinsic healing. Nonetheless, the results for the grafts were tarnished by a depressed repair surface and a histologic appearance not equivalent to that of normal cartilage. The application of growth factors to this model may yield a clinical treatment.
Migration of cells from human anterior cruciate ligament explants into collagen‐glycosaminoglycan scaffolds
Authors: Murray M. Meaney , Martin S. D. , Spector M.
Published: February 2005

Regeneration of the human anterior cruciate ligament after complete rupture offers several theoretical advantages over reconstruction, including maintenance of the complex insertion sites and fan‐shape of the ligament and preservation of remaining proprioceptive fibers within the ligament substance. Well vascularized connective tissues, such as dermis, heal as a result of migration of fibroblasts into a provisional scaffold, the fibrin clot. Wound closure is subsequently facilitated by a contractile cell phenotype. This study was designed to determine if fibroblasts intrinsic to the human anterior cruciate ligament were capable of migrating from their native extracellular matrix onto an adjacent provisional scaffold in vitro. Another objective was to determine whether any of the cells that successfully migrated into the scaffold expressed the contractile actin isoform, α‐smooth muscle actin, associated with wound contraction in other tissues. The results demonstrated that the cells intrinsic to the human anterior cruciate ligament were able to migrate into a collagen‐glycosaminoglycan scaffold, bridging a gap between transected fascicles in vitro. As a result of this cell migration and proliferation, areas in the scaffold contained cell number densities similar to those seen in the human anterior cruciate ligament in vivo. No extracellular matrix or tissue formation was seen in the gap between directly apposed transected ends of the anterior cruciate ligament explants cultured without an interposed collagen‐glycosaminoglycan scaffold. The fascicle‐collagen‐glycosaminoglycan‐fascicle constructs and the fascicle‐fascicle explants displayed minimal adherence after 6 weeks in culture. Any disruption in the contact area between explant and scaffold, even as small a gap as 50 μm, prevented cell migration from the explant to the collagen‐glycosaminoglycan scaffold at the area of loss of contact. All cells that migrated into the scaffold at early time periods expressed the α‐smooth muscle actin isoform. These results demonstrate that cells that migrate into and proliferate within the collagen‐glycosaminoglycan matrix have contractile potential as reflected in their expression of the α‐smooth muscle actin isoform. The role of these contractile cells in the healing process warrants further investigation. Moreover, this study demonstrates the potential of cells intrinsic to the human anterior cruciate ligament to migrate into collagen‐glycosaminoglycan scaffolds that may ultimately be investigated as implants to facilitate ligament healing and regeneration.
Bilateral proprioceptive defects in patients with a unilateral anterior cruciate ligament reconstruction: A comparison between patients and healthy individuals
Authors: Roberts David , Fridén Thomas , Stomberg Anders , Lindstrand Anders , Moritz Ulrich
Published: February 2005

Proprioception of the knee was measured in 20 patients with reconstructed anterior cruciate ligaments and in 19 age‐matched controls. The mean time from surgery was 2 years. Three tests of proprioception were used: (a) threshold to detection of passive motion from 20 and 40° toward flexion and extension, (b) active reproduction of a 30° passive angle change, and (c) visual reproduction of a 30° passive angle change. The aim was a complete, bilateral, proprioceptive evaluation of patients who had undergone reconstruction of the anterior cruciate ligament. As compared with those in the control group, the knees with reconstructed anterior cruciate ligaments had a higher threshold to detection of passive motion in the extension trials from 20 and 40° (p = 0.0003 and 0.04, respectively) and in the flexion trials from 20 and 40° (p = 0.004 and 0.0008, respectively). When the uninjured knees of the patients were compared with those in the control group, higher values for threshold to detection of passive motion were found in the flexion trials from 20° (p = 0.002) and 40° (p = 0.02). Thus, decreased proprioceptive ability was present in some measurements of these patients after reconstructive surgery, not only in injured knees but also in uninjured knees, as compared with the reference group. The functional relevance of these findings was not investigated in this study, but the results suggest that bilateral proprioceptive considerations should be made when evaluating prognostic factors, treatment, and risk of contralateral knee injury in patients with reconstructed anterior cruciate ligaments.
Comparison and reproducibility of fast and conventional spoiled gradient‐echo magnetic resonance sequences in the determination of knee cartilage volume
Authors: Cicuttini Flavia , Forbes Andrew , Asbeutah Akram , Morris Kevin , Stuckey Stephen
Published: February 2005

Quantitation of articular cartilage by magnetic resonance imaging and three‐dimensional reconstruction has been validated and is likely to be a useful outcome measure in clinical trials of arthritis. The cost of magnetic resonance imaging is largely dependent on scanning time. The aim of this study was to compare a fast spoiled gradient‐echo sequence magnetic resonance imaging scanning protocol, which takes 5 minutes and 44 seconds, with the standard, previously validated spoiled gradient‐echo sequence protocol, which takes 11 minutes and 56 seconds, in the measurement of knee cartilage volume. Cartilage volumes calculated from the standard and fast magnetic resonance imaging sequences were similar. The median absolute percentage overestimation or underestimation of the cartilage volume with the fast sequence for 10 normal subjects was 2.5, 4.1, and 3.2% for patellar, femoral, and tibial cartilage, respectively. For eight subjects with osteoarthritis, the percentages were 4.3 and 3.9% for femoral and tibial cartilage, respectively. The fast spoiled gradient‐echo sequence protocol had very high intra‐rater and inter‐rater reproducibility in normal subjects and in those with osteoarthritis. Because the cost of magnetic resonance imaging scanning is largely determined by scan time, the faster scanning protocol means that the cost of estimates of knee cartilage volume can be significantly reduced, thus increasing the feasibility of this methodology.
Spindle‐shaped cells derived from giant‐cell tumor of bone support differentiation of blood monocytes to osteoclast‐like cells
Authors: Miyamoto Noriki , Higuchi Yasumitsu , Tajima Masatoshi , Ito Morihiro , Tsurudome Masato , Nishio Machiko , Kawano Mitsuo , Sudo Akihiro , Uchida Atsumasa , Ito Yasuhiko
Published: February 2005

Spindle‐shaped cells were established from four giant‐cell tumors of bone. When human blood monocytes were co‐cultured with these cells, multinucleated giant‐cell formation of monocytes was induced. Intriguingly, even when a filter (pore size: 0.45 μm) was interposed between monocytes and the spindleshaped cells, polykaryocytes also appeared. These multinucleated giant cells were positive for tartrateresistant acid phosphatase, expressed calcitonin receptor, and showed bone‐resorption activity, characteristics of osteoclast‐like cells. These findings indicate that soluble factors secreted from these cells play an important role in osteoclast‐like cell formation from blood monocytes. These data additionally suggest that these cells support osteoclast‐like cell formation in giant‐cell tumors of bone. The cells also expressed mannose receptor, fibronectin, receptor activator of nuclear factorkB, and several cytokine mRNAs, including interleukin‐6, receptor activator of nuclear factorkB ligand/osteoclast differentiation factor/osteoprotegerin ligand, and macrophage colony‐stimulating factor, However, all of these molecules except receptor activator of nuclear factorkB ligand mRNA could also be detected in control HeLa and CV‐1 cells. Although the soluble receptor activator of nuclear factorkB ligand has not been found under physiological conditions, it is possible that it is cleaved by cellular proteases and the truncated receptor activator of nuclear factorkB is released from cells. Identification of the soluble factors capable of inducing osteoclast formation from blood monocytes is a pressing problem to be solved.
Cytokines associated with the pathophysiology of aggressive fibromatosis
Authors: Mills Barbara G. , Frausto Angelica , Brien Earl
Published: February 2005

The rare benign extra‐abdominal desmoid tumor is characterized by aggressive invasion of normal tissue. Treatment is complicated by its recurrence, invasiveness, and persistence. The etiology is unknown and the pathophysiology is obscure. Because of exuberant fibroblastic proliferation with collagenous tissue being the primary tissue component, this desmoid tumor has been compared with keloids arising from excessive scar formation in healing wounds. Numerous cytokines are associated with signaling for growth and maintenance of mesenchymal cells. Altered expression of these proteins is associated with many pathologic conditions. It has been proposed that the enhanced expression of platelet‐derived growth factor and its receptor characterize desmoid tumors. We tested the hypothesis that the exuberant fibrosis of desmoid tumors may have resulted from the initiation of the cascade of molecular events producing increased expression of cytokines. We used immunohistochemical analysis of cytokines in desmoid tumors compared with keloids and skin to localize the expression of cytokines. The results showed localized increased expression of the cytokines epidermal growth factor transforming growth factor‐β, tumor necrosis factor‐α, vascular endothelial growth factor, interleukin‐1β, and interleukin‐6 in the endothelial cells of blood vessels in the tumors. Production of tumor necrosis factor‐α and interleukin‐1β in tumor tissue was increased, but we did not find increased expression of platelet‐derived growth factor. We concluded that the increased expression of cytokines associated with angiogenesis usually found in wound healing and invasive tumors may contribute to the pathophysiology of the desmoid tumor.
Adaptation of post‐traumatic angiogenesis in the rabbit knee by apposition of torn ligament ends
Authors: McDougall Jason J. , Yeung Grace , Leonard Catherine A. , Sutherland Craig , Bray Robert C.
Published: February 2005

Apposition of torn ligament ends has been shown to have a beneficial effect on healing of the medial collateral ligament; however, the mechanism underlying this improved recovery is unclear. Excessive post‐traumatic angiogenesis, an inherent component of soft‐tissue regeneration, may be functionally detrimental in relatively hypovascular tissues such as ligaments. The present study therefore examined the relationship between contact of transected ligament ends and vascular remodeling. Female New Zealand White rabbits were subjected to a gap injury, Z‐plasty apposition, or sham operation to the midsubstance of the medial collateral ligament. Six weeks after treatment, the volume of vessels supplying the healing zone of the medial collateral ligament, as well as the ipsilateral lateral collateral ligament, posterior cruciate ligament, menisci, and medial capsule, was quantified by carmine red vascular casting. The volume of vessels supplying the neoligamentous scar formed by gap injury to the medial collateral ligament was found to be twice that of ligaments that had undergone the sham operation, and lateral collateral ligament and meniscal vascularity was also augmented in the injured joint. The medial collateral ligaments that underwent Z‐plasty apposition exhibited a level of vascularity comparable with that of the control ligaments that had undergone the sham procedure, whereas meniscal and lateral collateral ligament vascularities remained elevated in this group. Capsular and posterior cruciate ligament vascularities were unaffected by gap injury or Z‐plasty to the ipsilateral medial collateral ligament. These findings indicate that injury to the medial collateral ligament not only stimulates angiogenesis in the healing ligament, but other ipsilateral soft tissues also undergo vascular remodeling. Furthermore, apposition of an injured medial collateral ligament modifies these pro‐angiogenic events, and this may partly explain why contact of torn ligament ends is beneficial for post‐traumatic recovery of an injured joint.