Em Crawford

Prognostic value of markers of collagen remodeling in venous ulcers

A 25 patient study was conducted into the relationship between markers of collagen metabolism in venous ulcer exudates and healing status, and their prognostic value in predicting healing performance. Wounds were sampled on at least 5 occasions over 12 months, the frequencies of which were determined by the need for clinic attendance. Specimens were taken from several sites on each ulcer using sterile preweighed filters. Wound margins were traced and sites recorded for each collection. Sample sites were evaluated for severity as improving, static, or deteriorating according to subsequent wound progression. Specimens were analyzed for levels of proenzyme and active forms of matrix metalloproteinases 2 and 9, neutrophil elastase, and type I collagen C propeptide. There was an overall trend of greater expression of all markers with increasing severity of wound site, this being highly significant for pro‐matrix metalloproteinase‐9 (p = 0.006). For samples collected simultaneously from improving and deteriorating regions of the same wound, paired data analysis showed statistically significant differences for pro‐matrix metalloproteinase‐9 (p < 0.001), neutrophil elastase (p < 0.005) and activated matrix metalloproteinase‐9 (p < 0.05). Taken overall, these data show the potential of markers of collagen biochemistry as predictors of repair in venous ulcers; in particular pro‐matrix metalloproteinase‐9 and neutrophil elastase were found to be accurate prognostic indicators of subsequent healing.

Measurement of prothrombin time and activated partial thromboplastin time in citrated whole blood samples from clinically ill dogs following storage

OBJECTIVES To assess the reliability of prothrombin time and activated partial thromboplastin time results generated from citrated whole blood samples following short-term storage at room temperature. METHODS Clotting times were measured in blood samples from 40 dogs that showed a variety of clinical signs. Before measurement of prothrombin time and activated partial thromboplastin time in citrated plasma, whole blood samples were split in three aliquots; one was processed within 30 minutes of collection (fresh) while the remaining two were stored unseparated at room temperature for 24 (24RT) or 48 (48RT) hours. RESULTS The median prothrombin time for the 24RT (7 seconds) and 48RT (7·2 seconds) samples were not significantly different to those obtained from the fresh (7·1 seconds) samples but the median activated partial thromboplastin time for the 24RT (12·6 seconds) and 48RT (12 seconds) samples were significantly shorter than those obtained from the fresh samples (14·2 seconds). CLINICAL SIGNIFICANCE Storage of citrated whole blood at room temperature for 24 or 48 hours did not significantly alter the measurement of prothrombin time but resulted in significantly shorter activated partial thromboplastin time results. Extrapolating from these findings, it is proposed that unseparated clinical samples that are submitted to an external diagnostic laboratory for the performance of clotting times, may generate reliable prothrombin time but unreliable activated partial thromboplastin time results.