Nicole Schneider

Oxygen consumption of equine articular chondrocytes: Influence of applied oxygen tension and glucose concentration during culture

We investigated the oxygen (O2) uptake of equine articular chondrocytes to assess their reactions to anoxia/re‐oxygenation. They were cultured under 5% or 21% gas phase O2 and at glucose concentrations of 0, 1.0 or 4.5 g/L in the culture medium (n = 3). Afterwards, the O2 consumption rate of the chondrocytes was monitored (oxymetry) before and after an anoxia period of 25 min. The glucose consumption and lactate release were measured at the end of the re‐oxygenation period. The chondrocytes showed a minimal O2 consumption rate, which was hardly changed by anoxia. Independently from the O2 tension, glucose uptake by the cells was about 30% of the available culture medium glucose, thus higher for cells at 4.5 g/L glucose (n= 3). Lactate release was also independent from O2 tension, but lower for cells at 4.5 g/L glucose (n= 3). Our observations indicated that O2 consumption by equine chondrocytes was very low despite a functional mitochondrial respiratory chain, and nearly insensitive to anoxia/re‐oxygenation. But the chondrocytes metabolism was modified by an excess of O2 and glucose.

Plasma Concentration of Insulin-like Growth Factor I (IGF-I) in Growing Ardenner Horses Suffering from Juvenile Digital Degenerative Osteoarthropathy

Degenerative osteoarthropathy resulting in a reduced active lifespan was observed in Ardenner horses. In the context of joint biology, insulin-like growth factor I (IGF-I) is a potential candidate to affect the anabolism of cartilage matrix molecules. A group of 30 Ardenner horses reared under standardized conditions from weaning were evaluated periodically from 15 to 28 months of age to detect the early manifestations of the disease. At the end of this period, horses were classified in two pathological groups related to the degree of interphalangeal degenerative osteoarthropathy based on clinical and radiographic evaluations: healthy (46.7%) and pathological (53.3%) horses. Seven sequential blood samples were taken from each horse (during the evaluation period) to study the variation of IGF-I plasma concentration. We tested the variations of the IGF-I plasma concentration during growth, and the effect of sex and of pathological classes. Significant variations were observed during the research period, with a maximum value corresponding to spring and a minimum in autumn. A significant reduction of the IGF-I plasma concentration was also observed in the pathological horses (433.5 ± 19.5 ng/ml) compared to the healthy horses (493.9 ± 18.2 ng/ml). An alteration in the level of this growth factor could induce a disregulation of the mechanisms involved in the local control of joint and bone tissue development.

Plasma Concentrations of a Type II Collagen-derived Peptide and Its Nitrated Form in Growing Ardenner Sound Horses and in Horses Suffering from Juvenile Digital Degenerative Osteoarthropathy

Several breeds of draft horses suffer from degenerative digital osteoarthropathy, resulting in a reduced active lifespan. A group of 30 Ardenner horses was followed, in standardized conditions, from 15 to 28 months of age to detect the early manifestations of the disease. The severity of the disease was assessed according to a personal grading system including clinical and radiographic items. Coll 2-1, a peptide of the helical region of type II collagen, and its nitrated form (Coll 2-1 NO2) were assayed in blood plasma collected at 452 ± 18 days, 504 ± 20 days, 558 ± 18 days, 613 ± 19 days, 675 ± 19 days, 752 ± 21 days and 852 ± 19 days of age. At the end of the follow-up period, 53.3% of Ardenner horses were affected by a degenerative digital osteoarthropathy. A significant effect (p < 0.05) of time, sex and pathology was observed for Coll 2-1 NO2. Variations of Coll 2-1 were not significant except for the time effect. The elevation of Coll 2-1 NO2 in the pathological group could indicate an inflammatory process during the growth of the affected horses, as nitration of tyrosine is mediated through reactive oxygen/nitrogen species and/or myeloperoxidase activity. Coll 2-1 NO2 appears to be an interesting early marker of cartilage degradation and oxidation in degenerative osteoarthropathy.

Histology of two rice bodies isolated from the stifle of an adult draught horse stallion.

In the human and equine species, different kinds of free floating intra-articular particles are related to certain disorders. Osteochondral fragments formed during osteochondrosis dissecans are the most common finding in the equine species, whereas in humans rice bodies due to rheumatoid arthritis are more frequent. Herein we report a third type of floating body inside the stifle of an adult draught horse stallion, in macroscopic appearance similar to articular rice bodies known in humans. As revealed by histologic examination, the two particles consist of polypoid degenerated structures derived from synovial villi. Their formation was probably induced by ischemia.