Middle carpal cartilage explants from 4 horses with mild osteoarthritis involving that joint were maintained in tissue culture to test the effects of a polysulfated glycosaminoglycan (PSGAG) on proteoglycan synthesis and degradation. Cultures were exposed to 0.025 or 25 mg of PSGAG/ml for 48 hours, after which the medium was replaced with medium containing similar doses of PSGAG and 35S. Subsequently, the sulfated proteoglycan content of the medium and extracts of the explants was measured. Gel filtration chromatography was used to estimate the size and to purify the principal, large proteoglycan monomer, which was further characterized by digestion, using glycosidic enzymes. In a second experiment, explants were incubated with 35S for 48 hours, and were subsequently exposed to the same concentrations of the PSGAG for an additional 48 hours. The amount of remaining labeled proteoglycan was determined for culture medium and cartilage extracts. Gel filtration chromatography was used to assess the hydrodynamic size of the large proteoglycan monomer. Aliquots of proteoglycans from the second experiment were incubated in high-molecular weight hyaluronate and chromatographed to assess reaggregation. Polysulfated glycosaminoglycan caused a significant (P < 0.04) decrease in sulfated proteoglycan synthesis by cartilage explants. Radioactive proteoglycan content in explants labeled prior to exposure to PSGAG were similar. Large proteoglycan monomer size was similar in both experiments (median partition coefficient [K(AV)] = 0.40), and was not influenced by PSGAG treatment. Prelabeled explants exposed to hyaluronate and chromatographed under associative conditions had similar proportions of the radiolabel eluting as proteoglycan aggregate. Enzymatic digestion of newly synthesized large monomer revealed a mild dose-dependent increase in the proportion of keratan sulfate substitution on core protein. It was concluded that PSGAG in vitro, at the dosages evaluated, caused a decre.

Keratan sulfate (KS) is a glycosaminoglycan, distribution of which is confined mostly to hyaline cartilage. As such, it is a putative marker of hyaline cartilage catabolism. In experiment 1, a focal osteochondral defect was made arthroscopically in 1 radial carpal bone of 2 ponies, and in 2 other ponies, chymopapain was injected into the radiocarpal joint to induce cartilage catabolism. Sequential and concurrent plasma and synovial fluid concentrations of KS were measured, up to 13 months after induction of cartilage injury, to determine whether changes in KS concentrations reflected cartilage catabolism. In experiment 2, a large, bilateral osteochondral defect was made in the radial carpal bones of 18 ponies, which were subsequently given postoperative exercise and/or injected intra-articularly with 250 mg of polysulfated glycosaminoglycan (PSGAG). Medication was given at surgery, then weekly for 4 weeks. Blood samples were collected and synovial fluid was aspirated before surgery, when medication was given, and at postmortem examination (postoperative week 17). The KS concentration was measured in these fluids to determine whether changes in KS concentration indicated an effect of joint treatment. In experiment 1, the concentration of KS in synovial fluid was highest 1 day after joint injury, and the concentration in plasma peaked 2 days after joint injury. For ponies receiving chymopapain intra-articularly (generalized cartilage catabolism), a fivefold increase over baseline was observed in the concentration of KS in plasma (peak mean, 1.2 microgram/ml), and a tenfold increase over baseline in synovial fluid (peak mean, 2.0 mg/ml) was observed. On average, these maxima were threefold higher than values in fluids of ponies with osteochondral defects (focal cartilage disease). In experiment 2, nonexercised ponies had lower KS concentration (as a percentage of the preoperative concentration) in synovial fluid than did exercised ponies at all postoperative times, and.

Keratan sulfate (KS) is a glycosaminoglycan, distribution of which is confined mostly to hyaline cartilage. As such, it is a putative marker of hyaline cartilage catabolism. In experiment 1, a focal osteochondral defect was made arthroscopically in 1 radial carpal bone of 2 ponies, and in 2 other ponies, chymopapain was injected into the radiocarpal joint to induce cartilage catabolism. Sequential and concurrent plasma and synovial fluid concentrations of KS were measured, up to 13 months after induction of cartilage injury, to determine whether changes in KS concentrations reflected cartilage catabolism. In experiment 2, a large, bilateral osteochondral defect was made in the radial carpal bones of 18 ponies, which were subsequently given postoperative exercise and/or injected intra-articularly with 250 mg of polysulfated glycosaminoglycan (PSGAG). Medication was given at surgery, then weekly for 4 weeks. Blood samples were collected and synovial fluid was aspirated before surgery, when medication was given, and at postmortem examination (postoperative week 17). The KS concentration was measured in these fluids to determine whether changes in KS concentration indicated an effect of joint treatment. In experiment 1, the concentration of KS in synovial fluid was highest 1 day after joint injury, and the concentration in plasma peaked 2 days after joint injury. For ponies receiving chymopapain intra-articularly (generalized cartilage catabolism), a fivefold increase over baseline was observed in the concentration of KS in plasma (peak mean, 1.2 microgram/ml), and a tenfold increase over baseline in synovial fluid (peak mean, 2.0 mg/ml) was observed. On average, these maxima were threefold higher than values in fluids of ponies with osteochondral defects (focal cartilage disease). In experiment 2, nonexercised ponies had lower KS concentration (as a percentage of the preoperative concentration) in synovial fluid than did exercised ponies at all postoperative times, and at postoperative week 17, this effect was significant (P < 0.05). This may be related to decreased turnover of KS in articular cartilage attributable to stall confinement and late increase in turnover related to exercise. Seventeen weeks after surgery, synovial fluid from exercised, medicated ponies had significantly (P < 0.05) higher KS content than did fluid from exercised, nonmedicated ponies. This indicated that exercise, when combined with medication, may increase KS release from articular cartilage. Synovial fluid from medicated joints of nonexercised ponies had significantly (P < 0.05) lower KS concentration than did synovial fluid from nonmedicated joints of nonexercised ponies. This indicated that, in nonexercised joints, medication with PSGAG may have decreased either release of KS from the articular cartilage into the synovial fluid or inhibited synthesis of KS. Concentration of KS in synovial fluid was not related clearly to the development of osteoarthritis in these ponies. Exercise or medication did not affect plasma KS concentration, and synovial fluid and plasma KS concentrations were not correlated. Data indicated that KS concentration in plasma and synovial fluid may be increased in acute, marked, generalized articular cartilage catabolism and that KS turnover in cartilage of joints with large osteochondral defects was affected by intra-articular PSGAG and postoperative exercise.

Cartilage resurfacing by chondrocyte transplantation, using porous collagen matrices as a vehicle to secure the cells in cartilage defects, has been used experimentally in animals, This in vitro study evaluated the temporal morphologic features and proteoglycan synthesis of chondrocyte-laden collagen matrices. Forty-two porous collagen disks were implanted with a minimum of 6 X 10(6) viable chondrocytes, covered by a polymerized collagen gel layer, and 6 disks were harvested after 0, 3, 7, 10, 14, 18, or 22 days of incubation in supplemented Ham's F12 medium at 37 degrees C and 5% CO2. Histologic and histochemical evaluation of formalin-fixed segments of the cultured disks indicated that the chondrocytes proliferated in the implant, producing small groups and linear segments of cells by day 14. The collagen framework remained intact over the course of the study with thick areas attributable to depositions of matrix material after day 10. Alcian blue-stained matrix was evident in the pericellular region of chondrocytes in sections of disks harvested on days 14, 18, and 22. Glycosaminoglycan (GAG) assay by dimethylmethylene blue dye binding after papain digestion of the disk segments revealed negligible amounts of GAG at day 0. Significant (P < 0.0001) increase in total GAG content was observed by day 3 (0.329 micrograms/mg of disk) and further increases were observed until a plateau in GAG quantity was seen on day 14. Mean peak GAG content was 0.553 +/- 0.062 micrograms/mg. Secondary treatment of the papain-digested implants with keratanase and chondroitinase ABC yielded similar trends in chondroitin sulfate (CS) and keratan sulfate (KS) concentrations. The CS content significantly (P = 0.0002) increased for the first 14 days of incubation, then a plateau was observed for the remainder of the study. Peak CS content was 0.354 +/- 0.037 micrograms/mg. Concentration of KS reached a plateau earlier than did CS content, with peak amount of 0.193 +/- 0.027 micrograms/mg on day 10. Fluctuations in KS content were not significant until an increase on day 22. Chondrocytes actively populated the collagen implants, increasing in number and synthesizing matrix GAG epitopes over the 22 days of incubation. These results indicate that chondrocyte-laden porous collagen matrices may be suitable cartilage analogue materials and the optimal metabolic time for transfer to cartilage defects is 10 to 14 days.

Eight dogs were determined to be orthopedically normal on the basis of prelavage physical examination, stifle radiography, synovial fluid analysis, and force plate analysis (peak vertical force normalized for body weight, and time on the force plate). Each dog had 1 stifle randomly assigned to be lavaged with 100 ml of a commercially available 0.05% (w/v) chlorhexidine diacetate solution, and the contralateral stifle was lavaged with lactated Ringer's solution. Difference was not detected between the chlorhexidine diacetate and lactated Ringer's solution-treated joints, with regard to results of synovial fluid analysis and clinical lameness evaluations on days 4 and 8 after lavage. Chlorhexidine diacetate caused a more intense synovitis than did lactated Ringer's solution, as determined by histologic evaluation of synovial membrane specimens after necropsy on day 8; however, a difference in the intensity of toluidine blue staining of articular cartilage was not found between treatments. Chlorhexidine diacetate, as a 0.05% (w/v) solution, cannot be recommended as a joint lavage fluid until the duration of inflammatory changes in the synovial membrane are determined or until the chemical constituents of chlorhexidine diacetate causing the synovitis can be identified and removed.

Hexosamine concentration (an index of proteoglycan content), DNA content (an index of cellularity), and [35S]sulfate incorporation (an index of proteoglycan synthesis) of articular cartilage were measured in biopsy specimens from medial proximal sesamoid bone, medial condyle of the third metacarpal bone, and proximal dorsal rim of the proximal phalanx in both metacarpophalangeal joints of 6 adult horses. One limb was then placed in a fiberglass cast that extended down from the proximal portion of the metacarpus and enclosed the hoof; the other limb was not casted. After 30 days of staff confinement, additional specimens were taken from the medial proximal sesamoid bone, medial condyle of the third metacarpal bone, midproximal portion of the proximal phalanx, distal portion of the proximal phalanx, and proximal portion of the middle phalanx of both limbs for comparison. Immobilization resulted in an apparent decrease in the hexosamine content of the cartilage when the 30-day immobilized vs 30-day mobilized specimens were analyzed. This decrease was accentuated by opposing trends in the 2 limbs. The immobilized cartilage tended to lose hexosamine, whereas the mobilized limb tended to gain hexosamine during the 30-day period; a similar trend also was seen with [31S] incorporation, but this trend was not statistically significant. The largest change was a significant increase in glycosaminoglycan synthesis in the mobilized limb, compared with little change in the immobilized joint cartilage. We concluded that contralateral limbs are unsuitable for controls in immobilization studies because of their biological response to increased weight bearing. We also concluded that the changes in articular cartilage found following simple cast immobilization of 30 days' duration are minor and probably of little clinical consequence.

Middle carpal cartilage explants from 4 horses with mild osteoarthritis involving that joint were maintained in tissue culture to test the effects of a polysulfated glycosaminoglycan (PSGAG) on proteoglycan synthesis and degradation. Cultures were exposed to 0.025 or 25 mg of PSGAG/ml for 48 hours, after which the medium was replaced with medium containing similar doses of PSGAG and 35S. Subsequently, the sulfated proteoglycan content of the medium and extracts of the explants was measured. Gel filtration chromatography was used to estimate the size and to purify the principal, large proteoglycan monomer, which was further characterized by digestion, using glycosidic enzymes. In a second experiment, explants were incubated with 35S for 48 hours, and were subsequently exposed to the same concentrations of the PSGAG for an additional 48 hours. The amount of remaining labeled proteoglycan was determined for culture medium and cartilage extracts. Gel filtration chromatography was used to assess the hydrodynamic size of the large proteoglycan monomer. Aliquots of proteoglycans from the second experiment were incubated in high-molecular weight hyaluronate and chromatographed to assess reaggregation. Polysulfated glycosaminoglycan caused a significant (P < 0.04) decrease in sulfated proteoglycan synthesis by cartilage explants. Radioactive proteoglycan content in explants labeled prior to exposure to PSGAG were similar. Large proteoglycan monomer size was similar in both experiments (median partition coefficient [K(AV)] = 0.40), and was not influenced by PSGAG treatment. Prelabeled explants exposed to hyaluronate and chromatographed under associative conditions had similar proportions of the radiolabel eluting as proteoglycan aggregate. Enzymatic digestion of newly synthesized large monomer revealed a mild dose-dependent increase in the proportion of keratan sulfate substitution on core protein. It was concluded that PSGAG in vitro, at the dosages evaluated, caused a decrease in proteoglycan synthesis, had little effect on labeled proteoglycan degradation, did not influence the size of large monomer, and caused a modest increase in the concentration of keratan sulfate in proteoglycans synthesized by osteoarthritic equine chondrocytes.

Microscopic examination of the nasal mucosa of clinically normal specific-pathogen-free pigs and of toxicogenic type-D Pasteurella multocida toxin challenge-exposed specific-pathogen-free pigs indicated that the surface epithelium in pigs of both groups was microscopically normal; erosions or appreciable inflammatory changes were not evident. In pigs of both groups and in aU 3 regions of the nasal cavity, the endothelial lining of all blood vessels appeared normal without detectable changes to the walls at postinoculation day 10. Vascular injury in the cartilage or the bone was not discernible in control or challenge-exposed pigs. There were marked differences in the osseous structures of the conchae when the 2 groups were compared. In control pigs, active bone formation and remodeling were observed, and the septal cartilage was normal. In toxin challenge-exposed pigs, there likewise was normal bone formation and remodeling in the vestibular region, and the septal cartilage was normal. In marked contrast, conspicuous changes were observed in the osseous core of the conchae of the respiratory and, sometimes, the olfactory regions. These changes consisted of bone necrosis and resorption by large numbers of osteoclasts with variable replacement by dense mesenchymal stroma, which resulted in conchal atrophy. In the absence of any discernible damage or injury (angiopathy) to the nasal vessels, it appears that the action of the dermonecrotoxin of P multocida serotype D is on the most active osteoblasts and the associated organic matrix of the bone, with subsequent disruption of normal bone formation and remodeling of the nasal conchae.

The density of the cricoid cartilage from 29 equine larynges collected from an abattoir was determined by dual photon absorptiometry (DPA). Densities of the right and left cricoid cartilages were highly correlated. No correlation was found between age of the horse and the density of the cricoid cartilage.