Advances in wound healing physiology: the comparative perspective

Abstract Understanding of the processes involved in wound healing in vertebrates is increasing rapidly owing to the application of advances in cell and molecular biology, and in technology. The cellular mechanisms which result in some vertebrates having the ability to regenerate the dermis after injury, whereas in others it is replaced by scar tissue, are currently being explored with a view to restoring this regenerative ability by modulating the intercellular systems which control wound healing. This introductory review (a) compares and contrasts the response to injury of homoiofhermic and poikilothermic animals and of foetal and post-natal mammals; (b) describes the mechanisms involved in cutaneous wound healing; (c) illustrates how the rate and quality of healing can be assessed non-invasively and objectively, and (d) describes how cutaneous healing can be improved by the application of electrophysical modalities employing ultrasound and light. Zusammenfassung Unser Verständnis von Wundheilungsprozessen bei Wirbeltieren wächst wegen der Fortschritte in Zell- und Molekularbiologie und Technologie rapide. Die zellulären Mechanismen, die es einigen Wirbeltieren ermöglichen, die Haut nach einer Verletzung zu regenerieren, während sie bei anderen durch Narbengewebe ersetzt wird, werden gegenwärtig erforscht, um diese Regenerationsfähigkeit durch Veränderung der interzellulären Systeme, die die Wundheilung kontrollieren, wiederherzustellen. Diese einführende Übersicht (a) vergleicht die Reaktion auf Verletzung in homiothermischen und poikilothermischen Tieren und in Säugetierfeten und Säugetieren nach der Geburt; (b) beschreibt die Mechanismen der kutanen Wundheilung; (c) illustriert, wie die Heilungsrate und -fähigkeit nichtinvasiv und objektiv bewertet werden kann, und (d) beschreibt, wie Wundheilung durch die Anwendung von elektrophysikalischen Heilmitteln wie Ultraschall und Licht verbessert werden kann. [Dyson, M. Advances in wound healing physiology: the comparative perspective (Fortschritte in der Wundheilungsphysiologie: die vergleichende Perspektive). Veterinary Dermatology 1997; 8 : 227–233] Resumé La compréhension des processus impliqués dans la cicatrisation des plaies chez les vertébrés croït rapidement suite à l'application des progrès en biologie cellulaire et moléculaire et en technologie. Les mécanismes cellulaires qui résultent chez certains vertébrés dans la capacité du derme à se régénérer après une blessure alors que chez d'autres, il est remplacé par du tissus cicatriciel, sont actuellement explorés avec pour but de restaurer cette capacité régénératrice en modulant les systèmes intercellulaires qui contrôlent la cicatrisation des plaies. Cette revue d'introduction (a) compare et contraste la réponse des animaux homoiothermiques et poikilothermiques et des mammifères foetaux et postnataux au traumatisme; (b) décrit les mécanismes impliqués dans la cicatrisation des plaies; (c) illustre comment le taux et la qualité de cicatrisation peuvent être évalués de manière non invasive et objective; et (d) décrit comment la cicatrisation cutanée peut être améliorée par l'application de modalités électrophysiques utilisant ultra sons et lumière. [Dyson, M. Advances in wound healing physiology: the comparative perspective (Progres de la physiologie de la cicatrisation des plaies: les perspectives comparatives). Veterinary Dermatology 1997; 8 : 227–233] Resumen El conocimiento de los procesos implicados en la curación de heridas en los vertebrados aumenta rápidamente debido a la aplicación de avances en biologia celular y molecular, y a la tecnologia. Actualmente se estan estudiando los mecanismos celulares que hacen que algunos vertebrados tengan la capacidad de regenerar la dermis después de una herida, mientras que en otros se sustituye por tejido de cicatrización, con el objetivo de restaurar la capacidad regenerativa modulando los sistemas intercelulares que controlan la curación de heridas. Esta revision introductoria a) compara y contrasta la respuesta a las heridas en animales homoiotermos y poiquilotermos y en mamiferos fetales y post-natales; b) describe los mecanismos implicados en la curación de heridas cutáneas; c) ilustra cómo el ritmo y la calidad de curación puede ser monitorizado de forma no-invasiva y objetiva y d) describe como la curación cutánea mejora mediante la aplicación de modalidades electrofisicas utilizando ultrasonidos y luz. [Dyson, M. Advances in wound healing physiology: the comparative perspective (Avances en fisiologia de la curación de heridas: perspectiva). Veterinary Dermatology 1997; 8 : 227–233]     

Predation on walleye pollock (Theragra chakograrnma) eggs and yolk-sac larvae by pelagic crustacean invertebrates in the western Gulf of Alaska

Immunological detection of yolk protein was used to assess predation by pelagic amphipods (gammarid and hyperiid), mysids, and euphausiids on eggs and yolk-sac larvae of walleye pollock Theragra chalcogramma during 1988 and 1989. Consumption estimates were made on the basis of frequency of positive immunoassays, assay detection times (gut clearance time), predator abundance, and spatial overlap of predators and prey. From our results gammarid amphipods and euphausiids were important predators on eggs and yolk-sac larvae, respectively. Gammarid amphipods alone consumed about 14% of the standing stock of pollock eggs in 1989. These results were compared with those from clearance rate experiments of predators feeding on pollock eggs in 300-1 bags. In general, clearance rate estimates of egg consumption were lower than those determined from gut contents.     

Analgesia After Lateral Thoracotomy in Dogs Epidural Morphine Vs. Intercostal Bupivacaine

One of two analgesic treatments was randomly assigned to 40 dogs undergoing lateral thoracotomy. Group E (20 dogs) received an epidural injection of morphine (0.1 mg/kg) before surgery. Group I (20 dogs) received injections of bupivacaine around five intercostal nerves when the thorax was about to be closed. All dogs were given an opioid as part of their preoperative medication (meperidine or butorphanol), followed by thiopental for induction and halothane or methoxyflurane for maintenance of anesthesia. Scores were assigned for preoperative demeanor and response to restraint and injection. Alertness, undisturbed pain behavior, and response to palpation of the wound were assessed 3, 6, 12, and 24 hours after surgery. Dogs that appeared uncomfortable were given analgesics. Blood for evaluation of arterial blood gases was obtained at 3 and 6 hours after surgery. The person scoring the dogs was blinded to the treatment given. There were no statistically significant differences between the groups. Group E contained more "nervous" dogs (12 vs. 6) and more dogs in group E received postoperative analgesics (8 vs. 2). Both techniques appeared to provide adequate analgesia for most dogs.     

SCINTIGRAPHIC EVALUATION OF THE PROXIMAL METACARPAL AND METATARSAL REGIONS IN CLINICALLY SOUND HORSES

In recent years, pain arising from the proximal metacarpal and metatarsal regions has become well recognized as a cause of lameness and various disease entities have been identified. However, our knowledge of normal patterns of radiopharmaceutical uptake is limited, making interpretation of images problematic. It is therefore important to characterize normal patterns of radiopharmaceutical uptake at specific sites to ensure valid interpretation of images in clinical cases with subtle lesions. The purpose of this study was to describe the pattern of radiopharmaceutical uptake in the proximal metacarpal and proximal metatarsal regions in clinically sound horses. Scintigraphic images from 64 clinically normal horses were evaluated. All the images were assessed subjectively. The lateral, dorsal, and plantar scintigraphic images were assessed qualitatively using horizontal line profiles through the proximal metacarpal and proximal metatarsal regions. Mean ratios of radiopharmaceutical uptake were calculated from three regions of interest sited over the proximal metacarpal and proximal metatarsal regions and a reference site. In 78% of forelimbs the peak of radiopharmaceutical activity was at the dorsal to central portion of the proximal metacarpal region. Seventy-five per cent of the dorsal plane profiles of activity were symmetrical, with the highest peak over the medial to central portion of the proximal metacarpal region. In 80% of hindlimb lateral images the peak radiopharmaceutical activity was at the central to plantar aspect of the proximal metatarsal region. All (100%) plantar image profiles of activity were symmetrical, with the highest peak being over the lateral portion of the proximal metatarsal region. There was no significant left and right variation between sites for mean ratios on the lateral and dorsal images of the proximal metacarpal region. However, using lateral images the mean ratios from all regions of the right proximal metatarsal were greater than left (dorsal P = 0.003, plantar P < 0.0001 and whole proximal metatarsal, P = 0.0006). There was no significant variation in mean ratios between left and right on plantar images. However, the mean ratio for the lateral proximal metatarsal region was significantly greater than for the medial proximal metatarsal regions (P < 0.0001). There was no significant effect of age. Left/right symmetry of radiopharmaceutical uptake was shown in the proximal metacarpal region. However, there was a significant difference between left and right proximal metatarsal regions. There was higher radiopharmaceutical uptake in the right proximal metatarsal region than the left, which agrees with previous studies of the tarsal and metatarsophalangeal joints. There were differences in the pattern of radiopharmaceutical uptake between the forelimbs and hindlimbs. In the forelimbs maximum radiopharmaceutical uptake was located at the dorsal to central portion of the proximal metacarpal region in the lateral image, with peak activity over the medial to central portion of the proximal metacarpal region on dorsal images. In the hindlimbs the maximum radiopharmaceutical uptake was at the central to plantar aspect of the proximal metatarsal region in the lateral image, with peak activity over the lateral portion of proximal metatarsal region on plantar images. The results of this study support the hypothesis that there would be a standard pattern of radiopharmaceutical uptake across the proximal metacarpal and l metatarsal regions, but the pattern of uptake observed would be different in the proximal metacarpal region compared with the proximal metatarsal region. There was left/right symmetry of radiopharmaceutical uptake in the proximal metacarpal region. However, there was a significant difference between left and right proximal metatarsal regions, with higher radiopharmaceutical uptake in the right. There was no variation of radiopharmaceutical uptake pattern with age.     

Days lost from training by two‐ and three‐year‐old Thoroughbred horses: A survey of seven UK training yards

Reasons for performing study: The first major epidemiological study of injury incidence in the UK flat racing Thoroughbred (TB), published in 1985, found lameness to be the single largest reason for days when horses failed to train. It was considered advisable to ascertain if progress has been made in reducing the problem of musculoskeletal injuries in the intervening period. Objective: To quantify injury incidence and days lost from training by 2‐ and 3‐year‐old TBs in UK training yards during 2002 and 2003. Methods: One‐hundred‐and‐eighty‐two yearling TBs were recruited at the end of 2001 and daily training and injury records maintained over the following 2 training and racing seasons. Days were defined as lost from training when a horse failed to train at a slow canter speed or faster, and could be assigned to one of 4 categories: lameness, medical, traumatic and unknown. The incidence and number of days lost due to specific injuries and medical conditions was determined by further subdividing the lameness and medical categories. Results: The study period provided a total of 52,601 2‐year‐old and 29,369 3‐year‐old days available for training, with 2‐year‐olds failing to train on a significantly greater proportion of days available than 3‐year‐olds. Lameness was the most important condition causing horses to miss training, with stress fractures being the most important cause of lameness. Medical conditions were a relatively minor cause of days lost from training, accounting for approximately 5% of untrained days in the 2 age groups. Conclusions: In UK flat racehorses there has been little change in the proportion of days lost from training due to lameness over the last 20 years. Potential relevance: This study highlights the need for further efforts to reduce the problem of lameness in the racing TB.     

ULTRASONOGRAPHIC FINDINGS IN THE LUMBOSACRAL JOINT OF 43 HORSES WITH NO CLINICAL SIGNS OF BACK PAIN OR HINDLIMB LAMENESS

The transrectal ultrasonographic appearance of the lumbosacral joint was assessed in 43 horses with no history or clinical evidence of back pain or hindlimb lameness. In the majority of horses (34/43, 79.1%) the lumbosacral disc had uniform or mildly heterogeneous echogenicity. However, variation in the ultrasonographic appearance of the lumbosacral joint was also identified, including hyperechogenic regions within the lumbosacral disc with or without an acoustic shadow, and mild or moderate irregularity of the opposing surfaces of the last lumbar and the first sacral vertebral bodies. Marked irregularity of the bony surfaces or marked disruption of the lumbosacral disc was not seen in any horse. The mean distance between the ventral aspects of the last lumbar and first sacral vertebrae was 14.2 mm (range: 7.1–26.5 mm, median: 14.4 mm). The degree of protrusion of the ventral aspect of the lumbosacral disc ranged from 0 to 5 mm (mean: 1.32 mm, median: 1.2 mm). The mean angle between the ventral surfaces of the last lumbar and first sacral vertebrae was 147° (range: 118–165°, median: 150°). There was no significant effect of age, breed, gender, or the size of the horses on either subjective findings in the lumbosacral joint or objective measurements.     

Stem and bulb nematode, Ditylenchus dipsaci, associated with a dry rot of potato tubers

About 10% of the ware-sized tubers from a 1990 potato crop were found to have dry rot. The affected tubers had well defined circular patches of dry rot, either with the tuber surface depressed and cracked, or with deep, open cavities where the tuber surface had disintegrated. The rotted tissues contained large numbers of the stem and bulb nematode, Ditylenchus dipsaci. This is the first recorded case in the UK; dry rot of potato tubers is usually caused by the potato tuber nematode D. destructor.