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SUMMARY

Three sets of paired circular and square full-thickness skin wounds were made on the dorsum of the metacarpus (n = 48) of 8 horses. Each wound was 6.25 cm2 in area. The wounds were treated topically with an ointment, nonadherent dressing, and bandaged with a snug elastic wrap. Wounds were photographed every other day until healing was complete. Wound areas were measured and exponential and linear wound healing models were applied to the wound healing data generated. Wound healing variables measured for each wound were: number of days to healing, maximal size attained, rate of wound contraction (calculated by use of first-order and linear models), final wound size, and percentage of wound that healed by contraction.

The exponential model fit the data significantly better than the linear model. The maximal size attained by circular wounds was significantly smaller than the maximal size attained by square wounds. Wound shape did not influence the rate of wound healing. On the basis of our findings, conversion of circular defects to square defects would not speed wound healing.

Free access
in American Journal of Veterinary Research
in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association

Summary

A retrospective evaluation of 64 cases of suspected infectious arthritis in horses was undertaken to determine the relations among histopathologic findings in synovial membrane specimens, cytologic findings in synovial fluid samples, and bacterial culture results. Positive cultures were obtained from 55% of the joints, and 18 different bacterial organisms were cultured. Culturing of synovial fluid yielded bacterial growth more often than did culturing of synovial membrane. Histologic evaluation (h&e and Gram stain) of synovial membrane specimens provided little information to help distinguish infected from culture-negative joints. We do not advocate the routine use of closed synovial biopsy in suspected cases of equine septic arthritis.

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in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association

SUMMARY

The sodium-dependent transporter system responsible for L-glutamine uptake by brush border membrane vesicles prepared from equine jejunum was characterized. Vesicle purity was ascertained by a 14- to 17-fold increase in activity of the brush border enzyme markers. Glutamine uptake was found to occur into an osmotically active space with negligible membrane binding. The sodium-dependent velocity represented approximately 80% of total uptake and demonstrated overshoots. Kinetic studies of sodium-dependent glutamine transport at concentrations between 5 μM and 5 mM revealed a single saturable high-affinity carrier with a Michaelis constant of 519 ± 90 μM/ and a maximal transport velocity of 3.08 ± 0.97 nmol/mg of protein/10 s. Glutamine uptake was not affected by changes in environmental pH. Lithium could not substitute for sodium as a contransporter ion. 2-Methylaminoisobutyric acid inhibited the sodium-dependent carrier only minimally, but marked inhibition (> 90%) was observed in the presence of histidine, alanine, cysteine, and nonradioactive glutamine. Kinetic analysis of the sodium-independent transporter revealed it to have a Michaelis constant = 260 ± 47 μM and a maximal transport velocity of 0.32 ± 0.06 nmol/mg of protein/10 s. We conclude that glutamine transport in equine jejunal brush border membrane vesicles occurs primarily via the system B transporter and, to a lesser extent, by a sodium-independent carrier.

Free access
in American Journal of Veterinary Research

SUMMARY

Glutamine has been shown to be an important metabolic substrate of enterocytes in many animals, including cats, dogs, hamsters, human beings, monkeys, rabbits, rats, and sheep. To determine whether glutamine is important in the metabolism of cells of the equine gastrointestinal tract, we examined transintestinal differences in glutamine concentrations in the arterial and venous circulation, and measured activity of the major glutamine catabolizing enzyme, glutaminase. Arteriovenous differences provide an index of the amount of a given substrate removed by the tissue across which the measurements are made, and commonly are expressed as a percentage of substrate removed, or percent extraction. Arteriovenous differences for glutamine were determined in 7 anesthetized adult horses (weight, 450 to 500 kg) before and after an iv glutamine infusion. The mean baseline arterial glutamine concentration (± sem) was 572 ± 24 μM; this concentration quadrupled (to 2,167 ± 135 μM, P < 0.01) 1 minute after iv bolus infusion of a 17.5-g glutamine load. Baseline extraction by the portal-drained viscera was 7.5 ± 1.5%; this value increased to 18 ± 2% at 1 minute (P < 0.01) and had returned to baseline values 60 minutes later. Arteriovenous differences were greatest across the jejunum (11.8 ± 1.8% in the baseline period vs 33.1 ± 3.1% at 1 minute, P < 0.001), with smaller differences across the colon, suggesting that the jejunum was the more avid utilizer of glutamine. Glutaminase activity was 4.38 ± 0.16 and 4.00 ± 0.60 μmol/mg of protein/h under standard conditions in jejunal and ileal mucosa, respectively. Kinetic studies of jejunal glutaminase revealed the enzyme to have a Km of 3.81 ± 0.35 mM and a Vmax of 8.08 ± 0.54 μmol/mg of protein/h, suggesting that the small intestine of horses has a high capacity to extract and metabolize circulating glutamine.

Free access
in American Journal of Veterinary Research