bluuebunny/crossref_metadata_2025 huggingface dataset:
Epiphyseal replacement using developing tissue donors in a murine model: A combined histologic and radiographic study
Authors: Zaleske David J. , Floyd Waldo E. , Hallett Joseph , Kushner David , Jupiter Jesse , Trahan Carol , Ehrlich Michael G. , Mankin Henry J.
Published: February 2005

Epiphyseal transplantation has long been a goal of orthopaedic surgeons. While microvascular surgery has raised hopes that this goal could be achieved, factors other than blood supply also appear capable of affecting the function of the epiphysis. Basic reserch into the biology of the epiphysis appears to be required. This would be faciliated with a model of epiphyseal transplantation using a small mammal. The purpose of this experiment was to develop such a model in the mouse. Developing CD1 mouse or Lewis rat limb tissue was used to replace knee tissue that had been resected from CD1 postnatal mouse hosts. Donor tissue ranged from 14‐day embryonic mouse to 9‐day postnatal mouse or 18‐ and 19‐day fetal rat, which has a gestation similar to the mouse. The murine tissue is known to be avascular prior to the sixth postnatal day. The limbs were analyzed radiographically and histologically. The results show that epiphyseal replacement could be studied using developing tissue donors in a murine model. The results suggest that donor tissue prior to vascularization and tissue combinations with the least developmental time mismatch (the least heterochronicity) produced relatively the best, although still abnormal epiphyses.
Lectin‐binding histochemistry of intracellular and extracellular glycoconjugates of the reserve cell zone of growth plate cartilage
Authors: Farnum Cornelia E. , Wilsman Norman J.
Published: February 2005

The distribution of intracellular and extracellular lectin‐binding glycoconjugates of the reserve cell zone of growth plate cartilage was studied in the distal radial growth plate of 4‐week‐old Yucatan swine using a postembedment method on Epon‐embedded sections. Direct comparisons were made to articular, tracheal, and auricular cartilages not involved in endochondral ossification. All patterns of lectin binding that in the growth plate were restricted to the reserve cell zone were also patterns characteristic of tracheal, articular, and auricular cartilages. These included: (a) pericellular binding with peanut agglutinin (PNA) without prior digestion with neuraminidase; (b) pericellular binding with wheat germ agglutinin (WGA) at 24 h; (c) intracellular cytoplasmic binding to concanavalin A (CON‐A), Lens culinaris agglutinin (LCA), and Lotus tetragonobolus agglutinin (LTA) after periodic acid oxidation; and (d) a lack of pericellular binding with CON‐A and ricin agglutinin 1 (RCA‐1) after periodic acid oxidation. We conclude that reserve zone chondrocytes lack specific phenotypic markers as defined by lectin‐binding affinity that are found in the cellular zones of the growth plate that undergo calcification and vascularization. The reserve zone has identical lectin‐binding affinities to the three structural cartilages used as controls. One interpretation of these results is that the reserve zone may not be involved directly in endochondral ossification, but may have a structural function in growth plate cartilage.
Effect of irrigation and tourniquet application on aminoglycoside antibiotic concentrations in bone
Authors: Millan Michael Mac , Petty William , Hendeles Leslie
Published: February 2005

Preoperative antibiotics are an important measure taken to prevent infection in joint replacement surgery. The local availability of these antibiotics in the operative site is absolutely necessary to ensure adequate prophylaxis against contaminant bacteria. Because pulsatile‐lavage rapid‐recovery systems have become a routine technique of bone preparation in joint reconstruction, we chose to study the effect of these systems on local antibiotic concentrations. We further investigated the effect of irrigation with and without use of a limb tourniquet. For our study, we obtained 23 bone specimens in 16 patients undergoing joint reconstruction (14) or amputation (2). The patients were classified into one of four groups based on whether a tourniquet was applied during the procedure and whether the bone specimens were irrigated. In addition, matched blood samples were obtained to establish that therapeutic serum levels were achieved. Nine patients contributed 13 bone specimens, which underwent vigorous irrigation in vitro. None of these specimens had detectable levels of antibiotics, regardless of whether a tourniquet was used. Seven patients yielded 10 bone specimens, which were not irrigated. Five of these seven patients had detectable levels of antibiotics. In addition, the specimens from limbs without tourniquets had levels that averaged 0.51 μg/ml while those with tourniquets averaged below 0.2 μg/ml. Therefore, the use of vigorous irrigation in bone preparation has a significant deleterious effect on the local presence of previously administered systemic antibiotics. This effect is compounded if the operative site is isolated from continuous blood flow by use of a tourniquet. We therefore recommend that additional measures be taken to ensure that adequate antibiotic levels are present. Two methods that may have efficacy are application of antibiotic‐containing irrigants or antibiotic‐impregnated polymethylmethacrylate.
Analysis of experimental immune synovitis cartilage using monoclonal antibodies reactive to rabbit proteoglycan
Authors: Yoo Jung U. , Kresina Thomas F. , Malemud Charles J. , Goldberg Victor M.
Published: February 2005

This study details the macromolecular changes in cartilage involving proteoglycan molecules in an animal model of rheumatoid arthritis. In experimental chronic immune synovitis, fluorescein‐conjugated mouse IgG and three monoclonal antibodies (MAbs 2G2, 2E9, and 6C9) portraying differing fine antigenic specificity for rabbit cartilage proteoglycan monomer were utilized to detail alterations in cartilage proteoglycan. In normal and IgG immune animals, fluorescein isothiocynate (FITC)‐conjugated MAbs 2G2 and 2E9 stained cellular/pericellular (C/PC) region intensely. FITC‐MAb 2G2 stained cartilage interterritorial matrix as well. FITC‐MAb 6C9 stained only C/PC area lightly but did not stain matrix. A marked decrease in staining intensity with FITC‐MAb 2G2 was noted in cartilage sections derived from animals with immune synovitis. A corresponding increase in staining of cartilage was noted with FITC‐MAb 6C9. The augmented staining of articular cartilage with FITC‐MAb 6C9 was most prominent in femoral condyle tissue sections, which corresponded to the cartilaginous area, with the greatest severity in gross pathology. There was a slight augmentation of staining with FITC‐MAb 2E9, especially in the C/PC area of medial/femoral cartilage. In addition, the animals with immune synovitis showed abortive cartilage repair exemplified by the presence of chondrocyte cloning (up to 20 cells) which correlated with increased FITC‐MAb 2G2 staining. The differential MAb staining patterns of cartilaginous tissues obtained utilizing FITC‐conjugated monoclonal antibodies with known fine antigenic specificity indicates a modulation of proteoglycans involving predominantly core protein epitopes in the articular cartilage of animals with chronic immune synovitis.
Chondrons extracted from canine tibial cartilage: Preliminary report on their isolation and structure
Authors: Poole C. Anthony , Flint Michael H. , Beaumont Brent W.
Published: February 2005

We report on the morphology and structure of single and multiple chondrons isolated from homogenized samples of fresh and fixed canine tibial cartilage. Phase contrast, Nomarski, and scanning electron microscopy observations show each chondron to be composed of a chondrocyte and its pericellular matrix enclosed within a “felt‐like” pericellular capsule. The extraction of intact chondrons from cartilage homogenates confirms the structural validity of chondron concept and emphasizes the intrinsic mechanical strength of the capsule. Frayed collagen fibers radiate from multiple chondron columns suggesting a shear‐resistant, structural interrelationship between capsular components and type II collagen fibers. Future development of chondron extraction procedures could provide a unique model with which to study the structure, biochemistry, and function of articular cartilage chondrocytes and their pericellular microenvironment.
Residual muscular swelling after repetitive eccentric contractions
Authors: Fridén Jan , Sfakianos Peter N. , Hargens Alan R. , Akeson Wayne H.
Published: February 2005

This investigation illustrates the morphological changes that take place following eccentric exercise and correlates those changes with intramuscular pressure readings. Eight healthy male subjects were asked to exercise their right lower leg anterior compartment eccentrically and their left concentrically. Four hundred submaximal contractions were performed in each exercise regimen over a 20‐min period against a load corresponding to 15% of the individual's maximal dorsiflexion torque. Tissue fluid pressures were measured by the slit catheter technique before, during, and after exercise and 48 h later. Needle biopsies of both anterior tibialis muscles were also taken 48 h after completion of the exercise regimens. Overall morphology of the specimens revealed a greater cross‐sectional fiber area (both type 1 and type 2) in the eccentrically exercised muscle as compared with the concentrically exercised muscle. Scant evidence of infiammation (only 1 of 8 of the “eccentric” muscle samples) and no fiber necrosis was observed. Fiber type proportions were equal on both sides and type 1 fiber biased (70%). Extremely large type 2 fibers were found in 4 of 8 subjects from the eccentric specimens. This incidence correlated significantly with the length of the time to return to resting pressure after eccentric exercise (r = 0.93, p < 0.001). The percentage of water content was significantly higher in the eccentrically exercised muscle. Based on these findings, we conclude that muscle fiber swelling is a predominant feature following eccentric exercise and is directly associated with delayed muscle soreness.
Contact pressures in chondromalacia patellae and the effects of capsular reconstructive procedures
Authors: Huberti Helmut H. , Hayes Wilson C.
Published: February 2005

We measured patellofemoral contact areas and pressures using pressure sensitive film in ten human cadaver knees exhibiting degenerative lesions of patellar cartilage. We studied a flexion range from 20° to 90° and compared contact pressures before and after capsular reconstructive procedures. With an intact, normal capsule. localized lesions of grade I–II exhibited a 50% reduction in pressure (from 3.4 ± 0.7 MPa to 1.6 ± 0.9 MPa) directly over the lesion. Grade III–IV lesions exhibited a loss of contact pressure greater than 90%. This reduction in pressure appears to result from a loss of stiffness in the low grade cartilage lesions and from a loss of cartilage thickness in higher grade lesions. Highly localized peak pressures were also observed on the normal cartilage bordering the lesions. Capsular reconstructive procedures (medial plication, lateral release, and bilateral release) did not result in consistent pressure reductions or in the creation of more uniform pressure distribution. In particular, lateral capsular release, a popular surgical procedure, resulted in no change in three knees and four different pressure patterns in the other seven knees.
EMG profiles of knee joint musculature during walking: Changes induced by anterior cruciate ligament deficiency
Authors: Limbird Thomas J. , Shiavi Richard , Frazer Mardon , Borra Henry
Published: February 2005

A tear of the anterior cruciate ligament (ACL) disrupts the delicate balance of static stabilizers of the knee, leading to significant alterations in joint kinematics. Little is known about the dynamic compensatory responses of the patient to these kinematic alterations. This lack of quantitative information on the muscle synergy patterns has limited the surgeon's ability to evaluate various operative and rehabilitative techniques. Twelve subjects with documented ACL deficiency for a least 1 year and 15 normal participants were studied. Each subject was asked to walk at free and fast speeds on a 12 m walkway. The right and left foot contact patterns and the linear envelopes from the surface electromyogram (EMG) patterns of the gastrocnemius, medial and lateral hamstrings, rectus femoris, and vastus lateralis were measured. Significant differences were found in the muscle synergy patterns during walking. During the swing‐to‐stance transition, the ACL‐deficient subjects showed significantly less activity in the quadriceps and gastrocnemius muscles and more activity in the biceps femoris than in the normal group. During early swing, the vastus lateralis is more active than normal, and during midstance and terminal stance, the hamstrings appear to be less active than normal subjects. These dynamic compensatory mechanisms suggest that use of the hamstring tendons in reconstructive procedures may alter important compensatory mechanisms about the knee joint. Application of dynamic EMG techniques to the study of reconstructive procedures should provide additional information that will assist the clinician in the rational choice of a surgical procedure.
Analysis and measurement of neck loads
Authors: Moroney Sean P. , Schultz Albert B. , Miller James A. A.
Published: February 2005

To examine the loads imposed on the structures of the neck by the performance of physical tasks, a biomechanical model of the neck was constructed. The model incorporated 14 bilateral pairs of muscle equivalents crossing the C4 level. A double linear programming optimization scheme that minimized maximum muscle contraction intensity and then vertebral compression force while equilibrating external loads was used to calculate the muscle contraction forces required and the motion segment reactions produced by task performance. To test model validity, 14 healthy adult subjects performed a series of isometric tasks requiring use of their neck muscles. These tasks included exertions in attempted flexion, extension, and left and right lateral bending and twisting. Subjects exerted maximum and submaximum voluntary efforts. During the performance, surface myoelectric activities were recorded at eight locations around the periphery of the neck at the C4 level. Calculated forces and measured myoelectric activities were then linearly correlated. Mean measured voluntary neck strengths in 10 male subjects were as large as 29.7 Nm. Four female subjects developed mean strengths that were approximately 60%–90% of those of the males. In both sexes, neck muscle strengths were approximately one order of magnitude lower than previously measured lumbar trunk strengths. Mean calculated neck muscle contraction forces ranged to 180 N. Mean calculated compression forces on the C4‐5 motion segment ranged to 1164 N, lateral shear forces ranged to 125 N, and anteroposterior shear forces ranged to 135 N. Correlation coefficients between the calculated muscle forces and the measured myoelectric activities were as large as 0.85 in some muscles, but generally were smaller than this.
Symmetry of the canine femur: Implications for experimental sample size requirements
Authors: Sumner Dale R. , Turner Thomas M. , Galante Jorge O.
Published: February 2005

The purpose of this study was to determine the degree of bilateral variability in cross‐sectional geometric properties of the adult canine proximal femur and to use these data to deterrmine minimum detectable treatment effects in paired and independent experimental designs. Thirteen paris of canine femora were sectioned at nine locations and 16 cross‐sectional geometric properties were determined for each section location. The canine femur was found to be bilaterally symmetrical. For a given sample size, the magnitude of the detectable treatment effect was (a) smaller for diameters than for areas and area moments of inertia and (b) smaller within the middiaphysis than proximally. The data from this study can be used to estimate sample size requirements for experiments in which the treatment effect is determined by using the contralateral femur as a control. It was found that an increase from 3 to 7 animals would have a much greater effect on improving the sensitivity of an experiment than would an increase from 7 to 11 animals.
A reflection scanning acoustic microscope for bone and bone‐biomaterials interface studies
Authors: Meunier A. , Katz J. L. , Christel P. , Sedel L.
Published: February 2005

A relatively simple scanning acoustic microscope (SAM) that operates in the reflection mode has been constructed. The system uses a 20 MHz spherically focused transducer, acting both as transmitter and as detector, to obtain acoustic impedance information on a thin surface layer at a maximum resolution of approximately 100 μm. The specimen is mounted on an X‐Y driving system (precision, 5 μm) under computer control in order to scan a grid of 256 × 256 points across areas ranging from 6.5 to 1300 mm2. An algorithm is used to reference the data against standards; specially developed software provides for pseudo‐color mapping, three‐dimensional images, zooming to 16X magnification, contouring, and single line profiles of the data. The system has been used to determine inhomogeneities in surface acoustic properties of mineralized tissues and implant materials, in many cases as a complement to using ultrasonic wave propagation techniques to measure the bulk anisotropic properties.
Extracellular matrix alterations during endochondral ossification in humans
Authors: Horton William A. , Machado Mirta M.
Published: February 2005

Immunohistochemical methods were employed to examine alterations in the cartilage extracellular matrix constituents associated with endochondral ossification in humans. The distributions of chondroitin 4‐ and 6‐ sulfate and keratan sulfate proteoglycan (PG) determinants. cartilage PG link protein. collagen types I and II. and fibronectin were determined in iliac crest growth‐plate specimens using the avidin‐biotin‐horseradish peroxidase system. Collagen type II was distributed throughout the growth plate, providing a framework within which chondrocytes divided and formed clusters of differentiating (hypertrophic) cells. The septa between these clusters and their subchondral extensions into underlying bone trabeculae were rich in PG. PG link protein, and collagen type II and resembled the extracellular matrix of reserve cartilage. The territorial matrix associated with the differentiating cells within the clusters contained reduced amounts of collagen type II, PG link protein, and possibly cartilage PG. Collagen type I and fibronectin were detected within the cytoplasm of the maturing and degenerating cells, and fibronectin localized intensely to the pericellular matrix envelopes of these cells. These alterations presumably facilitate the degradation of the matrix associated with the cell clusters by invading vascular tissue, while the septa. which retain the characteristics of more typical cartilage matrix, are not degraded and firmly anchor the cartilage to the subchondral bone.
Demonstration of type I and type II somatomedin receptors on bovine growth plate chondrocytes
Authors: Trippel S. B. , Chernausek S. D. , Van Wyk J. J. , Moses A. C. , Mankin H. J.
Published: February 2005

The chondrocytes of the epiphyseal growth plate are the presumed target cells for hormones regulating skeletal growth. The somatomedins, a family of low molecular weight peptides, are thought to play a stimulatory role in this regulation. The cellular actions of the somatomedins are themselves determined by binding to specific receptors on target cells. Previous studies have characterized a specific receptor for somatomedin‐C (Sm‐C) or insulin‐like growth factor I (IGF‐I) on bovine growth plate chondrocytes (GPCs). We now report the characterization of a second type of somatomedin receptor on these cells that is more specific for another class of somatomedin represented by multiplication‐stimulating activity (MSA) or rat insulin‐like growth factor II (rIGF‐II). Binding of [125I]MSA/rIGF‐II to isolated GPCs was time dependent and saturable. Unlabeled Mr 7.100 MSA/rIGF‐II and Sm‐C/IGF‐I were approximately equipotent in competing with [125I] MSA/rIGF‐II for binding. while Mr 8,600 MSA/rIGF‐II was an order of magnitude less potent. Low levels of competition by insulin appeared in some studies at concentrations of 10−7 M and higher. suggesting displacement of [125I]MSA/rIGF‐II binding. to the Sm‐C/IGF‐I receptor. In affinity‐labeling studies. [125I]Sm‐C/IGF‐I labeled a complex of Mr >300.000 (unreduced) and of Mr 140.000 (reduced). consistent with a type I somatomedin receptor composed of disulfide‐linked subunits. [125I]MSA/rIGF‐II labeled a Mr 240.000 moiety (unreduced) and Mr 260.000 (reduced). consistent with a type II somatomedin receptor. Both affinity‐labeling and kinetic data revealed cross‐binding of MSA/rIGF‐II and insulin with the type I receptor and of Sm‐C/IGF‐I with the type II receptor. In contrast. the type II receptor did not recognize insulin. These data suggest a complex pattern of graded specificity of these receptors for their ligands. These data are consistent with the hypothesis that IGF‐II as well as Sm‐C/IGF‐I participate in the stimulation of skeletal growth.
Motions and loads within the human pelvis: A biomechanical model study
Authors: Scholten P. J. M. , Schultz A. B. , Luchies C. W. , Miller J. A. A.
Published: February 2005

The pelvis, a major load carrying component of the musculoskeletal system, is sometimes suspected as a site of mechanically provoked low back pain. Thus, studies of its basic biomechanics seem warranted. This study used biomechanical model simulations to examine how pelvic geometry and joint soft tissue properties influence relative motions among its bones and internal loadings of its joints. A biomechanical model of a pelvis was loaded by forces of up to 1000 N and moments of up to 25 Nm. Its resulting motions and joint loadings were determined. The effects on these responses due to pelvic geometry changes of 20% in lengths and 10° in angles, and soft tissue stiffness changes, most of which were 25%, were also examined. For all situations examined, model pelvis relative displacements were at most a few mm, and relative rotations were at most a few degrees. Internal forces and moments were always less than 530 N and 30 Nm, respectively.
The effects of demineralized bone matrix and direct current on an “in vivo” culture of bone marrow cells
Authors: Friedenberg Zachary B. , Brighton Carl T. , Michelson James D. , Bednar John , Schmidt Richard , Brockmeyer Thomas
Published: February 2005

Bone marrow cells (BMCs) from rabbit femora and tibiae were grown in diffusion chambers implanted in rabbit muscle. At 42 days 80% of the BMC chambers exhibited cartilage formation within them. Demineralized bone matrix added to the marrow cell suspension in the chamber accelerated the appearance and increased the number of chambers with cartilage. Mineralization of the cartilage also occurred earlier in the chambers with bone matrix. In a second experiment, a 5‐μA direct current cathode in the bone marrow chamber increased the number of chambers containing cartilage from 50 to 80% at day 25. Mineralization also occurred earlier in the chambers with direct current.
Nonlinear viscoelastic properties of articular cartilage in shear
Authors: Spirt Adrienne A. , Mak Arthur F. , Wassell Richard P.
Published: February 2005

The strain dependence of the intrinsic viscoelastic properties of the cartilage matrix in shear was investigated. Stress relaxation experiments were performed on bovine articular cartilage at shear strains ranging from approximately 3% to 16%. The tissue was found to exhibit nonlinear strain‐dependent viscoelastic behavior, with the nonlinearity occurring primarily in the short‐time transient during stress relaxation. In addition, the equilibrium stress was found to fit a quadratic relation with strain. This relationship was noted to be nearly linear with strain from 3% to 16%. The instantaneous stress was seen to be highly nonlinear, and followed a cubic relationship with applied shear strain. Fung's quasilinear theory can be used to describe the stress relaxation response over the range of strains examined when a nonlinear regression is performed to determine an “average” normalized relaxation function. Alternately, strain dependence can be incorporated into the model to describe and predict more accurately the strain‐dependent stress relaxation response.
Canine bone blood flow estimated with microspheres
Authors: Li Guoping , Bronk James T. , Kelly Patrick J.
Published: February 2005

Blood flow rate in the periosteal and endosteal cortices of the diaphysis of long bones was determined in eight anesthetized adult dogs using the radioactively labeled microsphere method. The flow rate in endosteal and periosteal cortices is not significantly different unless the endosteal cortex contains cancellous bone from the medullary cavity. The highest flow rate is in the ulna, with 6.50 ml/min/100 g for the endosteal cortex and 5.15 ml/min/100 g for the periosteal cortex. The lowest flow rate is in the femur, with 2.89 ml/min/100 g for the endosteal cortex and 2.29 ml/min/100 g for the periosteal cortex. The results of this study indicate that variation of blood flow does exist between bones of dogs. However, the flow rates of individual bone on the left and right sides in the same dog are not significantly different. This indicates that the data are reproducible and reliable, and differences are not an inaccuracy of the radioactively labeled microsphere method. The results also demonstrate that there are no significant differences in bone blood flow as measured with small numbers (fewer than 400 microspheres per sample) and large numbers (more than 400 microspheres per sample) of microspheres. The adequate number of microspheres in each bone sample is 150–250. Therefore, a dose of 0.5 × 106 spheres/kg body weight can be sufficient.
Internal deformations of intact and denucleated human lumbar discs subjected to compression, flexion, and extension loads
Authors: Seroussi Richard E. , Krag Martin H. , Muller David L. , Pope Malcolm H.
Published: February 2005

Three rows of six evenly spaced 0.5 mm metal beads were implanted midsagittally into the discs of ten L4–5 human lumbar motion segments. The intradiscal bead displacements in response to compression, flexion, and extension loads were obtained by digitizing the bead positions from sagittal plane radiographs taken before and during the load application. Each disc was denucleated and the loading process was repeated. For the intact discs, in compression, the intradiscal bead displacements were predominantly anterior. In flexion, the beads in the center of the disc moved posteriorly whereas the beads closer to the periphery of the disc moved anteriorly. In extension, the central beads moved anteriorly and the beads closer to the periphery of the disc moved posteriorly. After denucleation, the bead displacements for compression and flexion implied an inward bulging of the inner wall of the annulus, despite outward bulging of the disc surface. We hypothesize that the inward bulging causes radial tensile stresses within the disc, leading to disruption of adjacent layers of annulus.
Tibial anatomy and functional axes
Authors: Yoshioka Yuki , Siu David W. , Scudamore R. Allan , Cooke T. Derek V.
Published: February 2005

Articular geometry of the tibia has been studied in relation to the functional axis and extra‐articular bone landmarks, using a Cartesian coordinate system. Thirty‐one cadaver limbs were used, 26 of them paired. The donor age range was 61 to 89 years (17 females, 14 males), none of whom showed evidence of significant arthritic deterioration. Most linear parameters were greater in males than females (p < 0.005), and correlations between these parameters were noted, e.g., tibial length versus plateau width (r = 0.7, p < 0.01) with both genders combined. Gender differences occurred in only two of the angular parameters—tibial torsion (p < 0.025) and foot rotation (p < 0.005). For the latter, mean rotation was internal (−5°) for males, and external (11°) for females. No correlations between angular parameters were found. In the paired limbs, there was asymmetrical distribution of just two parameters—varus tilt of the tibial plateau margins (p < 0.005) and lateral deviation of the tuberosity (p < 0.025). The data complement a previous report on the femur. These studies are relevant to the kinematics of the lower limb, design and sizing of resurfacing components, and possibly to the pathogenesis of osteoarthritis.
Ingredients of a successful grant application to the national institutes of health
Authors: Gordon Stephen L.
Published: February 2005

Many factors determine the scientific merit of an NIH research grant application. This paper is intended to help optimize the organization and logical development of investigators' research ideas so that grant applications will be evaluated by the reviewers in as favorable a light as possible. The ingredients of a successful grant application are good ideas, good science, and a good application. The research should be based on a significant hypothesis and, if possible, oriented towards uncovering an important biological mechanism. Specific methods should be directly related to each aim of the project. Likewise, the specific aims should be related to each hypothesis. All aspects of the application should be clear and focused. It is best to define all assumptions, limitations, and alternative approaches. In general, the best philosophy is for the applicant to address all possible problems before the reviewers do.
Articular cartilage and intervertebral disc proteoglycans differ in structure: An electron microscopic study
Authors: Buckwalter Joseph A. , Smith K. C. , Kazarien L. E. , Rosenberg Lawrence C. , Ungar Robin
Published: February 2005

Articular cartilage and the intervertebral disc tissues have different material and biological properties and different patterns of aging and degeneration. To determine if the proteoglycans of these tissues differ in structure, we used the electron microscopic monolayer technique to compare baboon articular cartilage proteoglycans with baboon annulus fibrosus, transition zone, and nucleus pulposus proteoglycans. Intervertebral disc and articular cartilage porteoglycans differed signficantly. Articular cartilage contained large proteoglycan aggregates formed from hyaluronic acid central filaments, multiple monomers, and large nonaggregated monomers. These molecules were identical to those of nasal cartilage, growth plate cartilage, chondrosarcomas, or menisci. In contrast, the intervertebral disc tissues contained only nonaggregated proteoglycan monomers and clusters of monomers without apparent central filaments. Intervertebral disc nonaggregated monomers were shorter and more variable in length than those from articular cartilage, and nucleus pulposus nonaggregated monomers were even shorter and more variable in length than transition zone and annulus fibrosus monomers. These observations suggest that significant differences in proteoglycan metabolism exist between articular cartilage and intervertebral disc.
Omental angiogenic lipid fraction and bone repair. An experimental study in the rat
Authors: Nottebaert M. , Lane J. M. , Juhn A. , Burstein A. , Schneider R. , Klein Ch. , Sinn R. S. , Dowling Ch. , Cornell Ch. , Catsimpoolas N.
Published: February 2005

A lipid material extracted from the omentum has previously been shown to contain a potent angiogenetic activator (20), capable of creating intense vasoproliferation in traumatized tissues (19). This study was undertaken to analyze the efficacy of local administration of this omental lipid fraction on osseous vascularization and bone repair. An osteoperiosteal segmental femoral defect in the rat was replaced by a demineralized allogenic bone graft exposed to continuous local delivery of omental lipid via an implanted miniosmotic pump. Saline solution delivered in the same way served as a control. Neovascularization and bone formation in the transplant were quantitatively evaluated by means of dynamic radioisotopic bone imaging, radiographic photodensitometry, microangiography, and biomechanical testing. Compared with the control group, the omental lipid angiogenic fraction–treated specimens showed an 80% overall increase (p < 0.001) in bone density as well as a twofold increase (p < 0.001) in regional blood perfusion, maximal at 2 weeks following surgery. At 12 weeks, biomechanical testing demonstrated significantly higher union rate (p < 0.05) and strength (p < 0.01) in the treated specimens as compared with the controls. These data demonstrate that the omental lipid fraction factor has potent angiogenic properties that enhance bone blood perfusion and bone regeneration.
The effect of radiation on the fracture repair process. A biomechanical evaluation of a closed fracture in a rat model
Authors: Markbreiter Lance A. , Pelker Richard R. , Friedlaender Gary E. , Peschel R. , Panjabi M. M.
Published: February 2005

The effects of a single dose of irradiation on the biomechanical parameters of the fracture healing process were studied in a rat model. Intramedullary pinning was performed before production of a closed femoral midshaft fracture. The experimental group was exposed to 900 rad 3 days after fracture and was compared with a control group with a similar fracture that received no irradiation. Animals were killed at intervals ranging from 2–16 weeks after surgery and the bones were tested until failure in torsion. In the irradiated groups, a delay of 4 weeks was noted in the biomechanical parameters associated with fracture healing (torque to failure, torsional stiffness, angle to failure, and biomechanical stage). Despite this delay in the normal temporal progression, the staging and stiffness approached normal controls within an 8‐week period. However, the torque to failure remained below normal levels at the conclusion of this study. These results differ from a previous study using an open fracture model.
Low body weight as a risk factor for hip fracture in both black and white women
Authors: Pruzansky Mark E. , Turano Michael , Luckey Marjorie , Senie Ruby
Published: February 2005

A lower incidence of hip fracture in black women has been reported by several studies. The most frequently proposed explanations for this phenomenon have included a genetically greater bone mass, better preservation of bone due to the fact that certain populations of black women perform more physical labor, and the impact of other unidentified environmental and/or life‐style factors. This retrospective study demonstrates that low body weight is as significant a risk factor for hip fracture in black women as it is in white women. Coupled with the known higher prevalence of obesity in the older black female population, the findings of this study suggest that differences in body weight may be a significant and possibly sufficient explanation for the lower incidence of hip fracture in black women.
Effects of chondroitinase‐ABC on proteoglycans and swelling properties of fibrocartilage in bovine flexor tendon
Authors: Koob Thomas J.
Published: February 2005

Fibrocartilaginous regions of bovine deep flexor tendon were treated with chondroitinase‐ABC and trypsin in order to extract proteoglycans from the extracellular matrix and thereby investigate the contribution of proteoglycan and collagen organization to tissue material properties. Chondroitinase‐ABC digestion of tendon specimens for 24 h resulted in extraction of 60% of tissue glycosaminoglycan and leaching of the degraded large proteoglycan from the tissue residue. The totally degraded core protein of the small dermatan sulfate proteoglycan remained with the tissue residue, indicating that it is specifically associated with the tissue residue and that this association is not dependent on the glycosaminoglycan chains. Treatment of residues with trypsin after chondroitinase‐ABC digestion depleted the specimens of proteoglycan. Bulk swelling tests on enzyme‐extracted specimens showed that the distinct swelling properties of the fibrocartilaginous regions of the distal flexor tendon could be partially accounted for by elevated levels of proteoglycan. Swelling tests also showed that the distinct collagen organization of this region contributes significantly to the tissue's material properties. These results suggest that the fibrocartilaginous organization and composition of the articulating layer of distal tendon are adapted for mechanical requirements unique to this site, which receives compressive and frictional loads in addition to tensile loads.
Neutral metalloprotease from tendons
Authors: Piening C. , Riederer‐Henderson M. A.
Published: February 2005

Tendon repair following trauma, rupture, or surgery involves both synthesis and degradation of collagen in order to reweave new collagen bundles in with the old. Using an in situ assay on polyacrylamide gels containing gelatin, we have identified protease activity from tendon tissue and from tendon cells in culture. A population of synovial cells from the epitenon surrounding the tendon as well as the tendon fibroblasts themselves were examined. The cells and the conditioned medium from both cell populations exhibited a major band of gelatin‐degrading activity at 70 kdaltons and a minor band of activity at 60 kdaltons. When preparations were reacted with p‐aminophenylmercuric acetate (APMA) before electrophoresis, a third band appeared at 63 kdaltons. The main band at 70 kdaltons comigrated with a [35S]methionine‐radiolabeled protein band. Inhibitor and pH studies identified the enzymes as neutral metalloproteases requiring disulfide bonds for activity. No proteolytic activity was detected on casein‐containing gels, ruling out the presence of stromelysin. Since electrophoresis in the presence of SDS would separate the metalloprotease from the smaller molecular weight inhibitor (TIMP), these in situ assays provide a sensitive screening system for gelatindegrading enzymes present in tendon without prior removal of TIMP.
The effect of medial meniscectomy and coronal plane angulation on in vitro load transmission in the canine stifle joint
Authors: Newman Alan P. , Anderson D. Ron , Daniels A. U. , Jee Ken W.
Published: February 2005

The purpose of this study was to determine the in vitro load transmission characteristics of the canine stifle joint, paying particular attention to the positioning effect of the meniscus in the coronal plane. The intact joint was first loaded, and then tested under two different loading conditions after a complete medial meniscectomy. The first set of test conditions attempted to simulate those used by previous investigators, by ignoring the spacer effect of the meniscus and not repositioning the joint after its removal. The second set of tests was carried out after the joint was repositioned in the coronal plane to allow initial contact to occur in both tibiofemoral compartments. It is presumed that this occurs subsequent to a meniscectomy in vivo, following the application of any weight‐bearing load. As with previous investigators, it was found that after meniscectomy the joints produced slightly larger displacements and lower stiffnesses than when intact (no significant differences from intact). However, repositioning the meniscectomized joint produced markedly smaller displacements (35–49%, p < 0.01) and greater stiffnesses (47–123%, p < 0.05) over the range of forces analyzed, compared with the intact joint. The ratio of dissipated to input energy was 42% for the intact joint, and rose following meniscectomy to 54% (p < 0.05) with repositioning and 55% (p < 0.05) without repositioning. Measured contact area decreased by 17% (p < 0.05) following meniscectomy alone, and by 12% (p < 0.05) following meniscectomy with repositioning. Since repositioning of the joint subsequent to meniscectomy (accounting for the loss of the meniscal spacer) resulted in an increse in structural stiffness, it was concluded that the medial meniscus decreases the structural stiffness of the intact stifle joint. In addition, the meniscus has a role in elastic energy storage and increasing contact area. This study is intended to serve as a baseline comparison for future in vivo studies on meniscetomy, meniscal repair, and meniscal replacement, in addition to more fully elucidating the mechanism of load transmission. A model is presented to explain both the decrease in stiffness after meniscectomy without repositioning and the increase in stiffness after meniscectomy with repositioning, employing linear springs of unequal length and different stiffnesses. After removal of the softer meniscal element and allowing joint approximation to occur, loading of the stiffer articular element results in an initially stiffer preparation.
Centrifugal characterization of proteoglycans from various depth layers and weight‐bearing areas of normal and abnormal human articular cartilage
Authors: Müller Francisco J. , Pita Julio C. , Manicourt Daniel H. , Malinin Theodore I. , Schoonbeck John M. , Mow Van C.
Published: February 2005

Ultracentrifugal polydispersity differential [g(S)] distributions were determined for the proteoglycans of various postmortem human articular cartilage samples extracted from six lateral patellar grooves in nondissociative conditions after mild collagenase digestion of the tissue. The samples consisted of 53 slices (250 μm thick), from normal, mildly fibrillated, and extensively ulcerated knee joints. When statistically analyzed in various subgroupings, the obtained average sedimentation coefficients and polydispersity profiles supported the following conclusions: (a) loss of proteoglycan aggregation and sedimentability is confirmed to be a primary sign of cartilage matrix degradation; (b) higher S values for proteoglycans of the high weight (HW)‐bearing areas and lower values for those of the low weight (LW)‐bearing areas were a typical finding in normal cartilage samples; (c) inversion of this pattern was indicative of matrix degradation, suggesting that the HW regions are more affected than the LW‐bearing areas; (d) the average S value distribution across cartilage thickness tended to resemble the corresponding proteoglycan content versus distance from articular surface; and (e) the deepest cartilage layer had, in most cases, the smallest amount of aggregates while the highest average sedimentability was observed at the middle zone of the normal samples. In the discussion, a role of proteoglycan aggregation for providing a means to “pack” more proteoglycans within the collagen meshwork and to control the generation of osmotic pressure gradients is suggested.
Circulatory and mechanical response of skin to loading
Authors: Sangeorzan Bruce J. , Harrington Richard M. , Wyss Craig R. , Czerniecki Joseph M. , Matsen Frederick A.
Published: February 2005

We investigated the tolerance of skin to mechanical loading over the tibia and over the tibialis anterior muscle in 12 normal volunteers. Surface load, subcutaneous tissue pressure, skin deformation under load, and transcutaneous partial pressure of oxygen (TcPo2) were simultaneously monitored. The skin over bone showed a significantly stiffer load deformation relationship than the skin over muscle (p < 0.001). The displacement required to reduce TcPo2 to 0 over bone, 1.1 ± 0.3 mm (mean ± standard deviation), was significantly less than that required over tibialis anterior muscle, 5.4 ± 1.1 mm (p < 0.001). The applied pressure required to reduce TcPo2 to 0 was significantly greater for skin over muscle (71 ± 16 mm Hg) than for skin over bone (42 ± 8 mm Hg) (p < 0.001). However, the subcutaneous pressure required to reduce TcPo2 to 0 was not significantly different for skin over muscle (36 ± 11 mm Hg) than for skin over bone (28 ± 10 mm Hg) (p > 0.05). Our results indicate that skin over muscle tolerates greater locally applied loads and deformations because the pressure is lower within the tissue than when similar loads and deformation are applied to skin over bone. Cutaneous perfusion, as indicated by TcPo2, seems to be linked more closely to the subcutaneous tissue pressure than to the surface load or deformations. These results provide some data for predicting mechanical and physiologic response to locally applied loads such as those that may be encountered in prosthetic wear.
New technique for producing uniform partial lacerations of tendons
Authors: Hitchcock Thomas F. , Candel Antimo G. , Light Terry R. , Blevens Alexander D.
Published: February 2005

Previous experimental studies of partial flexor tendon lacerations have used tendons cut by hand with magnification and a scalpel. When we biomechanically tested chicken flexor tendons lacerated by hand through 75% of their cross‐sectional area, the tensile strength of the residual tendons varied substantially among specimens from different chickens as well as between digit matched pairs of tendons from the same animal. A device was designed that uses standard scalpel blades to create a uniform tendon laceration by leaving a constant area of tendon intact regardless of original tendon size or shape. With the instrument we have called the “tenotome,” a second group of chicken flexor tendons were lacerated through 75% of their cross‐sectional area. Biomechanical testing of the tendons cut with the tenotome showed significantly less variation when compared with the tendons cut by hand. Use of the tenotome permits the establishment of a more uniform model for partial flexor tendon injuries, and potentially decreases the number of specimens needed to demonstrate statistical significance.
Cytosolic ionized calcium concentration in isolated chondrocytes from each zone of the growth plate
Authors: Iannotti J. P. , Brighton C. T.
Published: February 2005

In isolated chondrocytes from the growth plate, there is an increase in both the cytosolic ionized calcium concentration and in total cell calcium content as the cells approach the mineralization front. The reserve zone chondrocytes have a cytosolic ionized calcium concentration, [Ca2+]i, of 124 ± 23 nM and a total cell calcium content, CaT, of 12.8 ± 6.8 nmol/mg cell protein. Proliferative zone chondrocytes have a [Ca2+]i of 172 ± 29 nM and a CaT of 16.1 ± 11.8 nmol/mg cell protein. Hypertrophic zone chondrocytes have a [Ca2+]i of 273 ± 49 nM and a CaT of 35.8 ± 16 nmol/mg protein. Chondrocytes isolated from the entire growth plate have a [Ca2+]i of 132 ± 29 nM and a CaT of 13.2 ± 2.5 nmol/mg cell protein. Chondrocytes isolated from noncalcifying hyaline cartilage have a [Ca2+]i of 85 ± 10 nM and a CaT of 11.5 ± 1.4 nmol/mg cell protein. There appears to be a correlation between intracellular calcium accumulation, an increase in the intracellular ionized calcium concentration, and the process of cartilage matrix mineralization.
Production of catabolin by synovium from an experimental model of osteoarthritis
Authors: Sabiston C. Paul , Adams Mark E.
Published: February 2005

Catabolic factors from synovium, or catabolins, may be important in the pathogenesis of osteoarthritis. The synovial production of catabolin in osteoarthritis was studied using the experimental model of osteoarthritis induced by section of the anterior cruciate ligament. At 1, 4, and 32 weeks after operation, the synovium was harvested, cultured, and the synovial conditioned medium assayed for catabolic activity. The synovial conditioned medium from the operated joints was significantly more capable of inducing cartilage destruction (p < 0.05) than was the synovial conditioned medium from the unoperated knees. However, when the results were expressed relative to the weight of synovium, the differences were not significant. These results suggest that the increased production of catabolic synovial factors in early experimental osteoarthritis is probably a result of the synovial hypertrophy.