Biopolymer-based hydrogels as scaffolds for tissue engineering applications: a review

Rural Industries Research and Development Corporation

Noninvasive assessment of bone mineral and structure: state of the art.

"Wolff's law" is a concept that has sometimes been misrepresented, and frequently misunderstood, in the anthropological literature. Although it was originally formulated in a strict mathematical sense that has since been discredited, the more general concept of "bone functional adaptation" to mechanical loading (a designation that should probably replace "Wolff's law") is supported by much experimental and observational data. Objections raised to earlier studies of bone functional adaptation have largely been addressed by more recent and better-controlled studies. While the bone morphological response to mechanical strains is reduced in adults relative to juveniles, claims that adult morphology reflects only juvenile loadings are greatly exaggerated. Similarly, while there are important genetic influences on bone development and on the nature of bone's response to mechanical loading, variations in loadings themselves are equally if not more important in determining variations in morphology, especially in comparisons between closely related individuals or species. The correspondence between bone strain patterns and bone structure is variable, depending on skeletal location and the general mechanical environment (e.g., distal vs. proximal limb elements, cursorial vs. noncursorial animals), so that mechanical/behavioral inferences based on structure alone should be limited to corresponding skeletal regions and animals with similar basic mechanical designs. Within such comparisons, traditional geometric parameters (such as second moments of area and section moduli) still give the best available estimates of in vivo mechanical competence. Thus, when employed with appropriate caution, these features may be used to reconstruct mechanical loadings and behavioral differences within and between past populations.

Who's afraid of the big bad Wolff?: "Wolff's law" and bone functional adaptation.

In vivo measurement of human tibial strains during vigorous activity

Summary

This paper describes a collaborative project, conducted under the auspices of the British Equine Veterinary Association's survey section and financed by the Horserace Betting Levy Board, with the objective of collecting relevant data from breeding and racing statistics and evaluating losses (areas of wastage) that occur in the Thoroughbred racing industry. The investigation, which was carried out between 1977 and 1980, was divided into 2 parts. In Phase 1 the available statistics showed that considerable wastage existed from the time of covering to the appearance of the progeny on the flat, but that losses were closely consistent each year. Of the active mares in the General Stud Book for the seasons 1973 to 1979, 11.8 per cent were eliminated because no covering return was received and a further 10.1 per cent were either not covered, were covered by halfbreds or foaled abroad. The remaining mares, which were confirmed to have been covered (ie, applicable covered returned mares) were used to base the estimates of wastage. These were failure to conceive, 22.5 per cent, aborted or had a non-surviving foal, 10.1 per cent, live progeny not named, 13.9 per cent, named animals not trained (2 to 4) years), 20.1 per cent and trained animals that did not run at 2 to 4 years, 6.2 per cent.



This gave an overall figure for wastage of 72.8 per cent. Data on the numbers of outings as well as the numbers of animals imported and exported are quoted. An estimate of the cost of these losses was made under the following categories: lost stallion fees, keep of mares, keep of unnamed foals and keep of named animals that did not run. The cumulative losses for the 1974 season and its progeny was calculated to be at least £15.2 million.



Phase 2 examined more specifically some of the areas of wastage caused by breeding losses and the reasons for an unsatisfactory number of racing appearances. The most substantial reason for not competing or competing less than the average number of times was horses showing little or no ability to race. In a survey of 762 horses, 26.5 per cent did not race up to the age of 4 years; of these just over one third were being kept as “store” animals for National Hunt racing. The final part of the survey examined the veterinary reasons for wastage. In 314 horses in Newmarket, lameness was the most significant factor. There was an incidence of lameness of 53 per cent at some periods during the season and in 20 per cent of cases the lameness was sufficient to prevent racing afterwards.



Resume

Cet article produit les resultats d'une etude menee sous les auspices de la commission d'enquete de la BEVA, etude financee par le British Horserace Betting Levy Board. L'objectif de cette etude etait de reunir des informations utilisables a partir des statistiques des courses et de l'elevage afin d'evaluer les pertes et les points faibles de l'industrie des courses de pur sang.



Les recherches ont ete conduites entre 1977 et 1980. Les resultats sont exposes en deux parties. Dans la premiere, les statistiques disponibles ont montre qu'un deficit considerable se produit entre la periode de monte et l'apparition de la production sur l'hippodrome; les pertes sont du meme ordre chaque annee.



11.8% des poulinieres repertoriees au General Stud Book ont eteecartees de l‘etude parce qu'aucun renseignement sur la monte n'a ete renvoye. En outre 10% des poulinieres furent ou bien non saillies ou bien saillies par des demi sang, d'autres mettant bas a l’etranger. On a donc retenu pour servir de base a l'estimation le reliquat, c'est-a-dire celles des poulinieres dont les resultats de saillie furent officiellement confirmes (renseignements effectivement “retournes”).



Les resultats furent les suivants:



— vides (n'ayant pas concu): 22.5%



— avortees ou ayant eu un produit qui n'a pas vecu: 10%



— production vivante non nommee: 13.9% (anonymes)



— animaux nommes qui n'ont pas etea l'entrainement entre deux et quatre ans: 20.1%



— animaux entraines qui n'ont pas couru entre 2 et 4 ans: 6.2%



Au total le deficit s'eleve a 72.8% Les donnees se rapportant au nombre d'animaux importes et exportes sont fournies.



Une estimation du montant des pertes ainsi constatees a ete faite sous les rubriques suivantes: pertes sur les couts de saillie — pertes sur l'entretien des juments — pertes sur l'entretien des poulains anonymes — pertes sur l'entretien des chevaux qui n'ont pas couru.



Cumulees, les pertes pour la saison 1974 et pour ceux des animaux nes cette annee lâ ont ete estimes a plus de 15.2 millions de livres sterling.



Dans la seconde partie, on examine plus particulierement quelques unes des sources de deficit et les raisons du nombre insuffisant des sorties en course. La raison la plus importante pour ne pas courir ou pour courir moins souvent que la moyen ne est l'inaptitude pure et simple a la competition. Pour 762 chevaux on constate que 26.5% d'entre eux n'ont pu courir avant l‘âge de 4 ans. Parmi ceux-ci un peu plus d'un tiers fut conserve pour les programmes de courses a obstacles. La derniere partie de cette enquete etudie les raisons “veterinaires” du deficit. A Newmarket, pour 314 chevaux on a trouve que la boiterie etait le facteur le plus important. A un certain moment, on a constate 53% de boiteries durant la saison et dans 20% des cas les boiteries ont empeche le retour a la competition.



Zusammenfassung

Dieser Beitrag beschreibt eine gemeinsame Untersuchung, die von der BEVA uberwacht und vom Horserace Betting Levy Board finanziert worden ist. Es wurde die Absicht verfolgt, relevante Angaben aus Zucht- und Rennstatistiken zu sammeln und die Verluste, die im Vollblut-Rennbetrieb sich einstellen, auszuwerten. Die Untersuchung erstreckte sich uber die Jahre 1977 bis 1980 und wurde in zwei Teilen vorgenommen. Die zuganglichen Statistiken zeigten, dass in Phase 1 ein erheblicher Verschleiss sich bemerkbar macht zwischen der Deckzeit und dem Erscheinen des Nachwuchses in Flachrennen. Diese Verluste veranderten sich von Jahr zu Jahr kaum. Von den “aktiven” Stuten im General Stud Book wurden zwischen 1973 und 1979 11.8 Prozent eliminiert, weil das Deckergebnis nicht gemeldet wurde und weitere 10.1% wurden entweder nicht belegt oder durch Warmbluthengste gedeckt, oder sie fohlten ins Ausland ab. Die verbleibenden Stuten (Stuten mit bekannten Deckangaben und Abfohler-gebnissen) dienten zu einer Verschleissschatzung:



Keine Konzeption 22.5%



Abort oder nichtuberlebendes Fohlen 10.1%



lebendes, namenloses Fohlen 13.9%



Tiere mit Namen, aber nicht im Training zwischen 2 bis 4 Jahren 20.1%



Im Training, aber nicht im Rennen zwischen 2 bis 4 Jahren 6.2%



Das ergibt eine Verschleissrate von 72.8%. Es werden auch Angaben gemacht uber die Anzahl der bestrittenen Rennen und uber die Zahl importierter, beziehungsweise exportierter Pferde.



Eine Schatzung der durch diesen Verschleiss verursachten Kosten wurde in den folgenden Kategorien angestellt: verlorene Sprunggelder; Kosten der Stutenhaltung; Kosten der Haltung namenloser Fohlen; Haltungskosten fur nicht in Rennen eingesetzte Pferde. Die kumulierten Verluste fur die Decksaison 1974 und fur die Produktion aus dieser Saison wurden auf mindestens 15.2 Mio Pfund geschatzt.



In Phase 2 der Untersuchung wurden bestimmte Aspekte dieser Zuchtverluste spezifischer ausgewertet und die Grunde fur die unbefriedigende Anzahl bestrittener Rennen erforscht. Der wichtigste Grund dafur, dass viele Pferde uberhaupt nie auf die Rennbahn kommen oder nur an einer unterdurch-schnittlichen Anzahl von Rennen teilnehmen, besteht in einer fehlenden oder ungenugenden Eignung als Rennpferd. Von 762 Pferden bestritten 26.5% bis zu einem Alter von 4 Jahren uberhaupt keine Rennen; davon wurde nur etwas mehr als ein Drittel fur den Einsatz in Hindernisrennen “aufgespart”.



Im letzten Teil der Untersuchung wurden die tierarztlichen Grunde fur die Verluste unter die Lupe genommen. Bei 314 Pferden in Newmarket wurde Lahmheit als weit wichtigster Grund festgestellt. Wahrend der Rennsaison ergaben sich Perioden mit einer Lahmheitsfrequenz von 53%, wobei 20% der lahmen Pferde auch spater nicht mehr in Rennen eingesetzt werden konnten.

An assessment of wastage in thoroughbred racing from conception to 4 years of age

Summary

The existence of an innate insulin insensitivity in ponies was investigated and compared with the situation in larger breeds of horse. Ponies that were fat or had previously suffered laminitis were found to be far more intolerant to oral glucose loading (1 g/kg bodyweight [bwt]) than normal ponies or Standardbreds. These ponies also exhibited a far greater response in plasma insulin levels after glucose loading. Insulin response tests (0.4 iu/kg bwt insulin intravenously) showed only a minimal and very protracted response in both the fat and laminitic groups. The relevance of these findings in regulation of carbohydrate and lipid metabolism, and their role in the pathogenesis of hyperlipaemia, are discussed.

Glucose tolerance and insulin sensitivity in ponies and Standardbred horses

The survey comprised 443 horses, referred to the clinical department of the Equine Research Station, with a history of a thoracolumbar (TL) complaint. A wide range of lesions were capable of producing back problems and more than one condition or site of injury was found in 75 animals (17 per cent). There were 103 horses (19.7 per cent) with no evidence of damage to the TL spine or its associated structures. In 66 of these cases, clinical signs were attributed to a variety of hindlimb lamenesses and, in 37, no specific diagnosis could be made. Soft tissue injury was diagnosed in 203 cases (38.8 per cent), the most frequent sites being the longissimus dorsi muscles and/or the supraspinous ligament in the caudal withers and cranial lumber regions. Chronic sacroiliac strain or mild sacroiliac instability was also a frequent cause of low back trouble in competitive horses. Other conditions included tying-up, subluxation of a lumbar vertebra and neuritis of the cauda equina. Fifteen cases (2.9 per cent) of vertebral malformations were found including scoliosis, lordosis and kyphosis. Vertebral lesions accounted for 202 (38.6 per cent) of the diagnoses. The most common condition was associated with crowding and overriding of the dorsal spinous processes in the caudal thoracic and cranial lumbar regions. This was most often diagnosed in competitive jumping horses (173 cases) and caused a loss of suppleness and spinal flexibility resulting in lowered performance and bouts of back pain. There was a comparatively low incidence of fractures (13 cases) and degenerative spondylosis (14 cases).

Disorders of the thoracolumbar spine of the horse - a survey of 443 cases.

Summary

This paper reviews current developments in equine osteochondrosis complex and the clinical syndromes associated with it. Although the primary lesion has been defined as a failure of endochondral ossification, its definitive cause is unknown and appears to involve heredity, growth rate, nutrition, mineral imbalance, endocrinological dysfunction and biomechanical trauma. Despite the international importance of osteochondrosis in horses, surprisingly few controlled investigations have been performed on its pathogenesis. The studies that have been conducted suggest that local effects on differentiating growth cartilage are the key to a more complete understanding of the problem. Gaps in the current knowledge include in-depth understanding of the life cycle of chondrocytes in growth cartilage, the process of mineralisation and the use of a standard experimental model for the induction of osteochondrosis. The ultimate goal of osteochondrosis research must be to prevent or reduce the incidence of the condition in horses.

Leo B. Jeffcott

Papers

An assessment of wastage in thoroughbred racing from conception to 4 years of age

Glucose tolerance and insulin sensitivity in ponies and Standardbred horses

Disorders of the thoracolumbar spine of the horse - a survey of 443 cases.

Osteochondrosis in the horse — searching for the key to pathogenesis

Twinning as a cause of foetal and neonatal loss in the Thoroughbred mare