Metabolic effects of avocado/soy unsaponifiables on articular chondrocytes.

Avocado/soy unsaponifiable (ASU) components are reported to have a chondroprotective effect by virtue of anti-inflammatory and proanabolic effects on articular chondrocytes. The identity of the active component(s) remains unknown. In general, sterols, the major component of unsaponifiable plant material have been demonstrated to be anti-inflammatory in vitro and in animal models.

Collagen Synthesis in tenocytes, ligament cells and chondrocytes exposed to a combination of Glucosamine HCl and chondroitin sulfate.

Clinical testing of the nutraceuticals glucosamine (glcN) and chondroitin sulfate (CS) has shown efficacy in providing relief from symptoms in osteoarthritic patients. In vitro and in vivo studies support existence of a synergistic relationship upregulating synthetic activity in chondrocytes. A combination of glcN and CS may also be useful as adjunct therapy in sports-related injuries if similar upregulation of collagen synthesis is elicited in accessory ligament and tendon joint tissue.

Smoking and osteoarthritis: differential effect of nicotine on human chondrocyte glycosaminoglycan and collagen synthesis.

Anecdotal suggestions and retrospective studies indicate an inverse relationship between the incidence of osteoarthritis and individuals who smoke. As a possible explanation, our studies confirm that nicotine upregulates glycosaminoglycan and collagen synthetic activity of articular chondrocytes at physiological levels seen in individuals who smoke.

Differential effects of nicotine and smoke condensate on bone cell metabolic activity.

Objective: Delayed or impaired healing of skeletal trauma in patients who smoke has been attributed to vascular responses of nicotine absorption and/or a direct effect of nicotine or other smoke components on bone cells. In vivo studies indicate variability in osteosynthetic response to nicotine versus smoke inhalation. We tested the hypothesis that components of cigarette smoke other than nicotine may be responsible for the adverse skeletal effects of smoking.

Glucosamine and chondroitin sulfate: biological response modifiers of chondrocytes under simulated conditions of joint stress.

Objective: To test the hypothesis that chondrocytes are more responsive to the chondroprotective agents, glucosamine (glcN) and chondroitin sulfate (CS), under in vitro conditions simulating in vivo joint stress.

Design: Synthetic and anticatabolic activities of bovine articular cartilage were assayed using 35-sulfate labeling and assaying the specific activity of glycosaminoglycans (GAGs) under the conditions of enzyme-induced matrix depletion, heat stress, mechanical compression and cytokine stress.

Results: The response of cartilage to simulated conditions of in vivo stress varies, depending on the type stress and age of the animal.

Protective effect of the chondroprotective agent Cosequin DS on bovine articular cartilage exposed in vitro to nonsteroidal antiinflammatory agents.

Studies were conducted to test the hypothesis that exposure of articular cartilage to a combination of the "chondroprotective" agents glucosamine hydrochloride, low-molecular-weight chondroitin sulfate, and manganese ascorbate (Cosequin DS [CDS], Nutramax Laboratories, Inc.) prevents the potentially adverse effects of NSAIDs on cartilage. Articular cartilage proteoglycan synthesis and degradation were used to monitor in vitro cartilage activity following timed exposure to levels of NSAIDs routinely applied in veterinary medicine.

In vivo chondroprotection and metabolic synergy of glucosamine and chondroitin sulfate.

Supplements of glucosamine hydrochloride, low molecular weight chondroitin sulfate, and manganese ascorbate were tested separately and in combination for their ability to retard progression of cartilage degeneration in a rabbit instability model of osteoarthrosis. Computerized quantitative histologic evaluation of safranin O stained sections of the medial femoral condyles measured the grade and extent of tissue involvement of lesions. Severe lesions (Mankin grade greater than 7) were absent in all animals supplemented with a dietary mixture of glucosamine, chondroitin sulfate, and manganese ascorbate.

Characterization of electrolytically prepared brushite and hydroxyapatite coatings on orthopedic alloys.

Details of a procedure for electrolytically preparing highly pure brushite (CaHPO4.2H2O) coatings on high surface area metal substrates are provided. The influence of current density and deposition time on coating morphology is described.

Growth hormone-releasing hormone depletion in the female rat: similarities to aging.

The age-related decline in growth hormone (GH) secretion has been largely attributed to age-related degeneration of hypothalamic growth hormone-releasing hormone (GHRH)-producing neurons. GH decline has recently been linked to age-related bone changes in humans. Bone loss and decreased bone strength are common in aging rats and humans, but density of remaining mineral tissue is known to be increased.

Is glutamate-induced reduction in growth hormone-releasing hormone a neuroendocrine model of aging in the rat?

Decreases in serum growth hormone (GH) associated with aging may be a result of age-related degenerative changes in neurons of the hypothalamus resulting in a decrease of growth hormone-releasing hormone (GHRH). This study tests the utility of glutamate-induced hypothalamic neuronal degeneration in the rat as a neuroendocrine model of aging. Sprague-Dawley female rats received three 4-mg/g monosodium glutamate (MSG) subcutaneous injections during the first 5 days following birth.

A large-deformation, finite-element study of chondrodiatasis in the canine distal femoral epiphyseal plate.

A large-deformation, finite-element analysis was conducted to model stress fields around the developing growth plate as a first approach to comprehend the clinical application of traction for limb lengthening procedures. The model chosen was a cross section through the distal femoral growth plate of a 14-week-old dog. The chosen section passed through two of the conformational bends (mammillary processes) formed by the natural convolutions of the physis.

Colony-forming efficiency response of bone marrow stromal cells to acute blood loss.

Colony-forming efficiency (CFE) was used to monitor the proliferative response of alkaline phosphatase-positive rabbit bone marrow stromal cells to acute blood loss. The CFE of animals subjected to a 1% blood loss was 0.97 compared with 0.

Treatment of nonunion by percutaneous injection of bone marrow and demineralized bone matrix. An experimental study in dogs.

Successful treatment of nonunited fractures remains a major clinical challenge. Because bone marrow and demineralized bone matrix (DBM) are capable of stimulating osteogenesis, experiments were designed to test the effectiveness of bone marrow or DBM or both when injected percutaneously into a canine nonunion model. Six-millimeter segmental defects were created in the midtibial diaphysis of 24 adult mongrel dogs and held distracted by external fixation.

The association of lipid abnormalities with tissue pathology in human osteoarthritic articular cartilage.

Articular cartilage is one of very few body tissues uniquely characterized as having substantial stores of lipid deposits. Lipid droplets are naturally accumulated by chondrocytes and individual fatty acids have been shown to have protective as well as deleterious effects on cartilage degradation in animal models of degenerative joint disease. As a means to better assess the role of lipids in human joint pathology, a comparative analysis of fatty acids was undertaken in small segments of osteoarthritic articular cartilage.

Electrophysiology of direct current stimulation of fracture healing in canine radius.

Electrophysiological mechanisms involved in the electrical stimulation of fracture healing remain largely unknown. The purpose of the present study was to establish relationships between osteogenetic response and intraosseous measures of electrical dose in experimental fractures (osteotomies) of canine radii stimulated by direct currents. The response was determined postmortem at seven weeks after osteotomy by measuring the bending rigidity and four physicochemical properties: tissue density, mineral density, matrix density, and mineral-to-matrix ratio.

Lipid and cell metabolic changes associated with essential fatty acid enrichment of articular chondrocytes.

Observations of impaired chondrocyte metabolism in essential fatty acid (EFA) deficiency as well as EFA protection against development of osteoarthrosis in inbred mice suggest the existence of a relationship between EFA, chondrocyte metabolism, and cartilage degeneration. To explore this relationship further, the fatty acid content of lipids in normal fetal bovine chondrocytes was manipulated by in vitro exposure to media supplemented with 100 microM arachidonic acid (20:4) or oleic acid (18:1). Chondrocytes rapidly and differentially incorporated both fatty acids into their lipid pools.

Metabolic and ultrastructural changes in articular cartilage of rats fed dietary supplements of omega-3 fatty acids.

A "marginally deficient" essential fatty acid state was produced in male Sprague-Dawley rats by dietary supplementation with omega 3 fatty acids. Animals fed diets containing the highest amounts of these fatty acids (10% menhaden fish oil) demonstrated a 70% maximum decrease in the linoleic and arachidonic acid content of articular cartilage, a 30-40% decrease in cartilage hexosamine content, with little effect on hydroxyproline levels, and a 32% inhibition of proteoglycan synthesis. Histologic analysis revealed an occasional surface irregularity and localized depletion of Safranin O and toluidine blue staining of articular cartilage on the femoral heads from animals taking the higher doses.

Quantitative roentgenographic densitometry for assessing fracture healing.

A noninvasive method was developed to assess fracture healing using optical densitometric methodology. Photometric measurements of osseous tissue density were based on illuminance or intensity of light, transmitted through standard roentgenograms. The method was tested in 6-mm tibial segmental defects and single-cut osteotomy defects in adult mongrel dogs.

Pulsing direct current-induced repair of articular cartilage in rabbit osteochondral defects.

Osteochondral defects in the distal femoral condyles of rabbits exposed to a pulsing direct current exhibits an enhanced quality of repair. The signal, with a peak value of 2 microA repeating at 100 Hz, imposed an electric field in the tissue of 20-60 mV/cm2. Maximum efficacy was seen with a shorter period of exposure (40 vs.

Mineral and matrix contributions to rigidity in fracture healing.

The purpose of this study was to investigate the relationships among selected properties of fracture callus: bending rigidity, tissue density, mineral density, matrix density and mineral-to-matrix ratio. The experimental model was an osteotomized canine radius in which the development of the fracture callus was modified by electrical stimulation with various levels of direct current. This resulted in a range of values for the selected properties of the callus, determined post mortem at 7 weeks after osteotomy.

Prostaglandin levels in unicameral bone cysts treated by intralesional steroid injection.

The etiology of the unicameral bone cyst remains undefined. Likewise, the treatment of the cyst has had proponents suggesting procedures ranging from decompression to diaphyseal resection. The use of intralesional steroids has gained popularity since its introduction in 1979 by Scaglietti.

Development of an osteogenic bone-marrow preparation.

The osteogenic effect of bone marrow was tested in rabbits, using chambers that had been implanted in the peritoneal cavity (ectopic site) and in a delayed-union model (orthotopic site). Osteogenesis was accelerated in both sites after concentration of marrow elements by centrifugation, but not after unit gravity sedimentation. Chambers that were implanted with marrow that had been processed by simple and isopyknic centrifugation demonstrated a more pronounced increase in deposition of calcium compared with whole-marrow implants of equal volume (101 compared with 193 per cent).

Stereological study of the developing distal femoral growth plate.

The distal femoral growth plate has a uniquely convoluted structure comprised of four mammillate processes. Factors contributing to the development of these processes and overall plate geometry were explored using three-dimensional image analysis of the canine distal femoral epiphysis. The growth plate at birth remains relatively flat until ossification of the epiphysis begins at 1 week of age.

Effect of aging on tensile mechanical properties of the rabbit distal femoral growth plate.

Tensile tests to failure were performed on the distal femoral growth plate of rabbits. The measured tensile forces, together with animal weight and dimensional measurements of the femur, were used to develop a noninvasive method of predicting growth failure loads and to examine the effects of age on the tensile strength of the growth plate. Growth plate failure load correlated with rabbit weight, (r = 0.

Uncertain effect of indomethacin on physeal growth injury. Experiments in rabbits.

Growth arrest and shortening remain significant sequelae of growth-plate injuries. Nonsteroidal anti-inflammatory agents, known to inhibit callus and bone formation, may be useful to diminish callus-induced growth effects after epiphyseal fracture. In this study, we created a longitudinal osteotomy of the medial distal femoral condyle in 54 rabbits to model a Type IV epiphyseal fracture.