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PubMed1989

[On the occurrence of blood vessels in the superficial layers of articular cartilage in bovine fetuses].

The occurrence of vascular networks in the superficial layers of articular cartilage of 51 bovine fetuses (10-93 cm CRL) and 3 calves was studied grossly and histologically. The networks were found regularly on the incisura trochlearis of the ulna, on the trochlea of the radius and talus, on the plantar articular surface of the head of the talus, on the proximal articular surface of the fused central and 4th tarsal bones, and less regularly on the articular surfaces of the distal phalanx and distal sesamoid (navicular) bone and on the cochlea of the tibia. The vessels coursed in the superficial stratum of the articular cartilage and were encountered in those places where synovial fossae or villi are found later. The vessels were not present in the calves.

Animals↗
PubMed2000

The effects of glucosamine derivatives on equine articular cartilage degradation in explant culture.

OBJECTIVE: To determine whether glucosamine-3-sulfate, glucose-3-sulfate (control) and N-acetyl glucosamine inhibit experimentally induced degradation of equine articular cartilage explants similar to glucosamine HCl. DESIGN: Articular cartilage was obtained from the antebrachio-carpal and middle joints of horses (2-8 years old) killed for reasons unrelated to lameness. Cartilage discs were harvested from the weight-bearing region of the articular surface and cultured. Media were exchanged daily and the recovered media stored at 4 degrees C. On days 1 and 2 lipopolysaccharide (LPS, 10 microg/ml) was added to induce cartilage degradation. To evaluate the effects of different sources of glucosamine (on an equal molar basis), varying concentrations of glucosamine HCl (0.25, 2.5, or 25 mg/ml), glucosamine-3-sulfate (0.304, 3.04, or 30.4 mg/ml), or N-acetyl-glucosamine (0.256, 2.56, or 25.6 mg/ml) were added to the cultures. The glucose-3-sulfate control was added at 0.3075, 3.075 or 30.75 mg/ml. Nitric oxide and proteoglycan released into conditioned media and tissue proteoglycan synthesis and total tissue PG content were measured as indicators of cartilage metabolism. RESULTS: Glucosamine-3-sulfate consistently inhibited cartilage degradation in a manner similar to glucosamine HCl, while the effects of N-acetyl-glucosamine were highly variable and did not inhibit cartilage degradation. Glucose-3-sulfate did not inhibit cartilage degradation. CONCLUSION: Our results indicate that glucosamine sulfate also has the potential to prevent or reduce articular cartilage degradation similar to glucosamine HCl in vitro. The amine group at the carbon-2 position appears important for the effectiveness of the glucosamine derivative. The therapeutic value of N-acetyl-glucosamine remains questionable.

Acetylglucosamine↗
PubMed1996

Decreased birefringence of the superficial zone collagen network in the canine knee (stifle) articular cartilage after long distance running training, detected by quantitative polarised light microscopy.

OBJECTIVE: To investigate the effects of a one year programme of running training (up to 40 km/day for 15 weeks) on the spatial orientation pattern of collagen and glycosaminoglycans in articular cartilage in different parts of the knee (stifle) and shoulder joints of young beagle dogs. METHODS: Area specific measurements of the optical path difference (= retardation, gamma) and the cartilage zone thickness were performed using conventional procedures and a new computer based quantitative polarised light microscopy method. Transmission electron microscopy was used to determine the zonal volume density of collagen fibrils. The concentrations of collagen and hydroxypyridinium crosslinks were investigated biochemically. RESULTS: Running training decreased gamma by 24-34% (p < 0.05) in the superficial zone of the lateral femoral condyle articular cartilage and at the centre of the tibial condyles. Gamma of glycosaminoglycans decreased by 26% (p < 0.05) in the superficial zone of the lateral condyle of the femur, but at the same site the volume density of collagen fibrils was unchanged. Neither the collagen concentration nor the concentration of hydroxypyridinium crosslinks was altered as a result of running. In both control and runner dogs, the thickness and gamma values of the superficial zone were greater in the humerus and the femur than in the tibia. CONCLUSION: Endurance type running exercise in beagles caused a reduction in the superficial zone birefringence of the articular cartilage, which indicates either a disorganisation or a reorientation of the superficial zone collagen network. Articular cartilage showed marked variability of collagen network organisation over the different knee (stifle) joint articular surfaces.

Amino Acids↗
PubMed2006

Validation of an in vitro single-impact load model of the initiation of osteoarthritis-like changes in articular cartilage.

The objective of this study was the development and characterization of an in vitro model of the initiation of traumatic osteoarthritis (OA). Articular cartilage was obtained from seven healthy horses and from four horses diagnosed with OA. Cartilage disks were subjected to a single-impact load (500 g from 25, 50, or 100 mm) using a simple drop-tower device and cultured in vitro for up to 20 days. Cartilage sections were examined histologically to observe surface damage and proteoglycan loss. Percentage cell death was determined using TUNEL, release of glycosaminoglycans (GAG) to the medium was measured using the DMMB assay, and percentage weight gain calculated. Following a single-impact load and subsequent culture in vitro, articular cartilage explants demonstrated characteristic surface damage, proteoglycan loss, and chondrocyte death. This closely resembled degenerative changes observed in OA cartilage samples. A kinetic study showed that these degenerative changes (increased weight gain, GAG release into the medium, and chondrocyte death) were initiated within 48 h following impact and increased with recovery time in culture. These parameters were proportional to impact height, that is, impact energy. In conclusion, articular cartilage disks subjected to a single-impact load followed by 48 h of recovery time in culture in vitro developed traumatic OA-like changes. These changes can be quantified and compared, making the in vitro single-impact load model a useful tool for the elucidation of the early molecular pathways involved in the process leading from trauma to cartilage degeneration.

Animals↗
PubMed2000

Development of articular cartilage: what do we know about it and how may it occur?

Articular cartilage has a fundamental role in joint function. While much is known about its structure, organization and biomechanical properties, there is a very poor understanding of how articular chondrocytes develop during embryogenesis and acquire the unique ability to organize and maintain the articular tissue. Given that articular cartilage forms in close juxtaposition with the joint, here we review past studies on limb joint determination and morphogenesis and more recent studies on a number of factors thought to have roles in joint and epiphysis development. These factors include: the homeobox gene Barx-1; the bone morphogenetic protein (BMP) family member GDF-5; the growth factors HGF and PTHrP; and the transcription factor ERG. We summarize current thinking on how these factors participate in joint development and how some of these factors may influence development and behavior of epiphyseal chondrocytes. We also describe pertinent recent studies from our laboratories on ERG and the newly-identified alternatively spliced variant C-1-1, and finally propose a sequela of events that may subtend the process of determination and emergence of articular chondrocytes during limb synovial joint development.

Animals↗
PubMed1989

The effect of ultrasonically induced cavitation on articular cartilage.

Cavitation, the term used to describe bubble activity in fluids, is a destructive phenomenon encountered in fluid systems. The effect of cavitation on articular cartilage was investigated by ultrasonically inducing bubble activity on the surface of bovine specimens. Distinctive pits and craters, not present on control specimens, were observed using scanning electron microscopy on the damaged surface. Human osteoarthrotic articular cartilage specimens were removed during arthroplasty and examined using scanning electron microscopy. Craters and pits observed on the osteoarthrotic specimens were similar in appearance to those on the cavitated specimens. The mechanism of cavitation bubble collapse could be responsible for damage in vivo, thus providing articular cartilage with a degenerative pathway toward osteoarthrosis.

Animals↗
PubMed1997

Biochemical effects of estrogen on articular cartilage in ovariectomized sheep.

Cartilage is a sex-hormone-sensitive tissue but the role of estrogen in the pathogenesis of osteoarthritis (OA) remains controversial. In this study, intrinsic material properties and thickness of articular cartilage of the knee joint of ovariectomized (OVX) and estrogen-treated sheep were measured. Skeletally mature ewes (N = 36, same breed, same housing 4-5 years old) were divided into; sham treated (n = 9), OVX (N = 13), OVX plus one estradiol implant (OVXE; N = 10) and OVX plus two estradiol implants (OVX2E; N = 4). Twelve months following sham procedure or OVX, sheep were euthanized and articular cartilage from a total of 216 points in the left femorotibial (knee) joints was tested for aggregate modulus, Poisson's ratio, permeability, thickness and shear modulus (six sites per sheep). When all of the sites in each knee were grouped together, OVX had a significant effect on articular cartilage. The sham cartilage of all sites grouped together had a larger aggregate modulus (P = 0.001) and a larger shear modulus (P = 0.054) than the OVX tissue. No statistically significant differences were seen for permeability and thickness between OVX, sham, OVXE and OVX2E. Differences existed in biomechanical properties at the different sites that were tested. Overall, no one location tended to be lowest or highest for all variables. This biomechanical study suggests that OVX may have a detrimental effect on the intrinsic material properties of the articular cartilage of the knee, even though the cartilage of the OVX animals appeared normal. Treatment with estradiol implants ameliorated these deleterious effects and may have helped maintain the tissue's structural integrity. Our study supports epidemiological studies of OA in women after menopause. The protective effect of estrogen and it's therapeutic effect remain to be further defined. This model may allow the relationship of estrogen and estrogen antagonists to be studied in greater detail, and may be valuable for the study of the pathogenesis and therapies of OA of postmenopausal women, particularly in its early stages.

Animals↗
PubMed1985

New structural concepts of articular cartilage demonstrated with a physical model.

The construction and function of a model of articular cartilage based on a system of deformable elements trapped within a three-dimensional network of fibrils is described. The network is generated from a radial array of elements appropriately crosslinked along their length. The model demonstrates in a qualitative sense how a soft composite tissue structure such as articular cartilage developed from a specific arrangement of two primary components exhibiting totally contrasting mechanical properties, i.e. tension resisting collagen fibrils and highly deformable hydrated proteoglycans, can have dimensional stability in its unloaded state and mechanical resilience under a wide range of loading conditions.

Biomechanical Phenomena↗
PubMed1988

A reappraisal of the structure of normal canine articular cartilage.

It has been shown that some of the controversy over the structure of articular cartilage may be due to slight differences in the orientation of the sample that has been studied. As our decisive criterion we have used the simple physical fact that elongate proteins, such as collagen micelles, that can exhibit form-birefringence, had to show virtually straight extinction when viewed under crossed polars. The use of a variably adjustable microtome chuck facilitated small adjustments in the orientation of the cartilage to meet this criterion. Under these conditions, the collagen of the matrix has been shown to be aligned mainly perpendicularly to the surface which was bounded by a thin lamina in which the collagen showed birefringence at 90 degrees to that of the matrix. The conventionally described zonation of articular cartilage has been shown to be inadequate for that of the dog tibial plateau. The conventional Zone 2 has been shown to consist of two zones, Zones 2a and 2b, with different cell sizes, cell concentrations, and concentration of matrix components.

Animals↗
PubMed2000

Squeeze-film lubrication of the human ankle joint with synovial fluid filtrated by articular cartilage with the superficial zone worn out.

A squeeze-film lubrication model of the human ankle joint in standing that takes into account the fluid transport across the articular surface is presented. Articular cartilage is a biphasic mixture of the ideal interstitial fluid and an elastic permeable isotropic homogeneous intrinsically incompressible matrix. The simple homogeneous model for articular cartilage models the case of early osteoarthritis, when the intact superficial zone of the normal articular cartilage, much stiffer in tension than the bulk material, has been already disrupted or worn out. The calculations indicate for this case that in normal approach motion the lubricating fluid film is quickly depleted and turned into a synovial gel film that is supposed to serve as a boundary lubricant if sliding motion follows

Ankle Joint↗
PubMed1987

In vitro characterization of porcine juvenile articular cartilage.

Dispersed cell cultures were established from the articular cartilage of the proximal portion of the humerus of young pigs. Articular and epiphyseal portions of the cartilage were separated, minced, and enzymatically dispersed, using bacterial collagenase. Morphologically, 2 cell types were observed, using phase-contrast microscopy. Smaller polygonal cells (32.5 +/- 3.5 microns diameter) containing cytoplasmic granules were found in both areas of the cartilage. In cultures from the articular region, cells grew as monolayer cultures and initially did not demonstrate contact inhibition. In cultures from the epiphyseal region, cells grew in a multilayered manner in a colonial arrangement with cells being released from the center of the colony into the culture medium. Small granular particles (0.03 to 0.08 micron diameter) were secreted by cells in both culture systems. Particle secretion was greater in epiphyseal cultures than in articular cultures with the rate decreasing as confluency was approached. These particles stained positively for lipid and alkaline phosphatase. Acridine orange was also incorporated into the granules. The 2nd cell type, a stellate-shaped cell (60 +/- 7.6 micron diameter), was found mainly surrounding the outside of colonial areas in epiphyseal cultures. These cells did not secrete small granular particles and stained positive for factor VIII. Evaluation of cultures by scanning and transmission electron microscopy further supported the presence of 2 cell types. With scanning electron microscopy, the smaller polygonal cell was characterized by varying sizes of blebs (0.03 to 0.1 micron diameter) associated with the cell membrane and small cytoplasmic processes projecting from the cell's surface.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

[Structural adaptations of the articular cartilage in fur-bearing animals under conditions of mobility].

Adaptive properties of the articular cartilage and plasticity of its structures under various conditions of static-dynamic loading on joints have been studied when the data obtained in sables and minks, living in natural biocenosis and in cages, are compared. By means of optic, raster electron microscopy and microroentgenological analysis, peculiarities of structural formation of the articular cartilage have been revealed in ontogenesis, as well as succession in formation of its zonal architectonics. Conditions of prolonged hypodynamia are manifected as a number of anomalies in distribution of the cartilagenous integument of the joints affecting cellular and tissue levels of adaptation.

Adaptation, Physiological↗
PubMed2005

Effect of hip hemiarthroplasty on articular cartilage and bone in a canine model.

The purpose of this study was to determine if acetabular articular cartilage damage occurs in the presence or absence of changes in subchondral plate thickness or porosity and trabecular bone architecture after hip hemiarthroplasty. Eight canines were sacrificed 6 months after receiving unilateral hemiarthroplasties in which a cobalt chrome alloy femoral head was used. The acetabular cartilage, subchondral plate, and trabecular bone were quantitatively evaluated. Although the articular cartilage in the treated hip showed gross and histologic degenerative changes, there were no differences in the treated and contralateral hips in any of the trabecular bone parameters or subchondral plate thickness. However, the subchondral plate porosity was increased 2.6-fold in the treated hip. Therefore, degradation of cartilage can occur in the absence of thickening of the subchondral plate or alterations in the supporting trabecular bone architecture. These observations provide a better understanding of the role that periarticular bone has in the degenerative process after hemiarthoplasty.

Acetabulum↗