Minor influence of lifelong voluntary exercise on composition, structure, and incidence of osteoarthritis in tibial articular cartilage of mice compared with major effects caused by growth, maturation, and aging.

We investigated the effects of lifelong voluntary exercise on articular cartilage of mice. At the age of 4 weeks C57BL mice (n = 152) were divided into two groups, with one group serving as a sedentary control whereas the other was allowed free access to a running wheel from the age of 1 month onward. Mice were euthanized at four different time points (1, 2, 6, and 18 months of age).

Sample size for prospective studies of hip joint space width narrowing in osteoarthritis by the use of radiographs.

Objective: To determine the number of participants required in controlled clinical trials investigating the progression of osteoarthritis (OA) of the hip as evaluated by the joint space width (JSW) on radiographs and to evaluate the reproducibility of the JSW measurement methods.

Materials And Methods: Anteroposterior radiographs of hip were taken from 13 healthy volunteers and from 18 subjects with radiographic hip OA. The reproducibility of the JSW was determined from four segments using digital caliper measurements performed on film radiographs and using semiautomatic computerized image analysis of digitized images.

Quantitative analysis of collagen network structure and fibril dimensions in cartilage repair with autologous chondrocyte transplantation.

Objective: The aim of this study was to undertake a stereological analysis to quantify the dimensions of the collagen network in the repair tissue of porcine joints after they had been subjected to autologous chondrocyte transplantation (ACT).

Method: ACT was used to repair cartilage lesions in knee joints of pigs. Electron-microscopic stereology, immunostaining for type II collagen, and quantitative polarized-light microscopy were utilized to study the collagen fibrils in the repair tissue 3 and 12 months after the operation.

Changes in collagen fibril network organization and proteoglycan distribution in equine articular cartilage during maturation and growth.

The aim of this study was to record growth-related changes in collagen network organization and proteoglycan distribution in intermittently peak-loaded and continuously lower-level-loaded articular cartilage. Cartilage from the proximal phalangeal bone of the equine metacarpophalangeal joint at birth, at 5, 11 and 18 months, and at 6-10 years of age was collected from two sites. Site 1, at the joint margin, is unloaded at slow gaits but is subjected to high-intensity loading during athletic activity; site 2 is a continuously but less intensively loaded site in the centre of the joint.

Effect of loading on the organization of the collagen fibril network in juvenile equine articular cartilage.

We investigated the effects of exercise-induced loading on the collagen network of equine articular cartilage. Collagen fibril architecture at a site (1) subjected to intermittent high-intensity loading was compared with that of an adjacent site (2) sustaining continuous low-level load. From horses exposed to forced exercise (CONDEX group) or not (PASTEX group), the spatial parallelism of fibrils and the orientation angle between fibrils and the surface at depths 9 microm apart through cartilage from surface to tidemark were determined using polarized light microscopy, and expressed as parallelism index (PI) and orientation index (OI).

Changes in subchondral bone mineral density and collagen matrix organization in growing horses.

Objective: The effects of growth and maturation on the mineral deposition and the collagen framework of equine subchondral bone (SCB) were studied.

Materials And Methods: Osteochondral specimens (diameter 6 mm) from the left metacarpophalangeal joint of 5-(n=8), 11-(n=8) and 18-month-old (n=6) horses were investigated at two differently loaded sites (Site 1 (S1): intermittent peak loading; Site 2 (S2): habitual loading). The SCB mineral density (BMD) was measured with peripheral quantitative computer tomography (pQCT), and the data were adjusted against the volume fraction (Vv) of the bone extracellular matrix (ECM).

Practical considerations in the use of polarized light microscopy in the analysis of the collagen network in articular cartilage.

Polarized light microscopy is a traditional method for visualizing the collagen network architecture of articular cartilage. Articular cartilage repair and tissue engineering studies have raised new demands for techniques capable of quantitative characterization of the scar and repair tissues, including properties of the collagen network. Modern polarized light microscopy can be used to measure collagen fibril orientation, parallelism, and birefringence.

Poly-L-D-lactic acid scaffold in the repair of porcine knee cartilage lesions.

Articular cartilage injuries cause a major clinical problem because of the negligible repair capacity of cartilage. Autologous chondrocyte transplantation is a surgical method developed to repair cartilage lesions. In the operation, cartilage defect is covered with a periosteal patch and the suspension of cultured autologous chondrocytes is injected into the lesion site.

Human articular cartilage proteoglycans are not undersulfated in osteoarthritis.

Chondroitin sulfate is the major constituent of cartilage. Inadequate sulfate availability results in the production of undersulfated proteoglycans. In osteoarthritis, there is a net loss of articular cartilage proteoglycans.

Reticulon 4 in chondrocytic cells: barosensitivity and intracellular localization.

Members of the reticulon gene family are endoplasmic reticulum (ER)-related proteins expressed in various human tissues, but their molecular functions are not understood. The reticulon 4 subfamily consists of three members, reticulon 4/Nogo-A, -B and -C. Reticulon 4-A is under intense investigation because of its inhibitory effect on neurite outgrowth, and reticulon 4-B has been suggested to induce apoptosis.

Effect of radiosynovectomy with holmium-166 ferric hydroxide macroaggregate on adult equine cartilage.

Objective: To analyze the effect of radiosynovectomy with holmium-166 ferric hydroxide macroaggregate (166Ho-FHMA) on articular cartilage in 6 adult horses.

Methods: Arthritic changes and mechanical properties of articular cartilage were evaluated with arthroscopy and postmortem microscopic analyses. Glycosaminoglycan content was measured by safranin-O staining combined with digital densitometry, uronic acid analyses, and dimethylene blue binding assay.

Reference sample method reduces the error caused by variable cryosection thickness in Fourier transform infrared imaging.

Fourier transform infrared imaging (FT-IRI) is a novel technique for characterization of the biochemical composition of biological tissues, e.g., articular cartilage.

Structure-function relationships in enzymatically modified articular cartilage.

The present study is aimed at revealing structure-function relationships of bovine patellar articular cartilage. Collagenase, chondroitinase ABC and elastase were used for controlled and selective enzymatic modifications of cartilage structure, composition and functional properties. The effects of the enzymatic degradations were quantitatively evaluated using quantitative polarized light microscopy, digital densitometry of safranin O-stained sections as well as with biochemical and biomechanical techniques.

Mechano-acoustic diagnosis of cartilage degeneration and repair.

Background: The combined use of high-frequency ultrasound and mechanical indentation has been suggested for the evaluation of cartilage integrity. In this study, we investigated the usefulness of high-resolution B-mode ultrasound imaging and quantitative mechanical measurements for the diagnosis of cartilage degeneration and for monitoring tissue-healing after autologous chondrocyte transplantation.

Methods: In the first study, osteochondral samples (n = 32) were obtained from the lateral facet of a bovine patella, and the samples were visually classified as intact (n = 13) or degenerated (n = 19) and were graded with use of the Mankin scoring system.

Spatial assessment of articular cartilage proteoglycans with Gd-DTPA-enhanced T1 imaging.

In Gd-DTPA-enhanced T(1) imaging of articular cartilage, the MRI contrast agent with two negative charges is understood to accumulate in tissue inversely to the negative charge of cartilage glycosaminoglycans (GAGs) of proteoglycans (PGs), and this leads to a decrease in the T(1) relaxation time of tissue relative to the charge in tissue. By assuming a constant relaxivity for Gd-DTPA in cartilage, it has further been hypothesized that the contrast agent concentration in tissue could be estimated from consecutive T(1) measurements in the absence or presence of the contrast agent. The spatial sensitivity of the technique was examined at 9.