bluuebunny/crossref_metadata_2025_split huggingface dataset:
A light microscopic and ultrastructural examination of calcified dental tissues of horses: 3. Dentine
Authors: KILIC S. , DIXON P. M. , KEMPSON S. A. 
Published: April 2010

SummaryUltrastructural examinations of equine dentine found that dentinal tubules extended from the amelodentinal junction towards the pulp forming primary curvatures. The number of dentinal tubules/unit area and their diameters increased significantly from the amelodentinal junction towards the pulp cavities, particularly in regular secondary dentine, but irregular secondary (tertiary) dentine contained no dentinal tubules. Dentinal tubules contained odontoblast processes that appeared to extend as far as the amelodentinal junction, but due to iatrogenic loss during specimen preparation, odontoblasts were seldom found in regular secondary dentine. In primary dentine, the dentinal tubules were surrounded by large amounts of peritubular dentine that increased in diameter from the amelodentinal junction towards the junction of primary and secondary dentine. The site of the dentinal tubule within the peritubular dentine varied at different dentinal sites. Peritubular dentine was present in primary dentine only and was surrounded by a thin layer of intertubular dentine. When acid etched, peritubular dentine gave dentine a honeycomb appearance adjacent to the junction of primary and secondary dentine.
A light microscopic and ultrastructural examination of calcified dental tissues of horses: 4. Cement and the amelocemental junction
Authors: KILIC S. , DIXON P. M. , KEMPSON S. A. 
Published: April 2010

SummaryUltrastructural examinations showed the diameter of cement lacunae to be greater in infundibular cement than in peripheral cement of upper cheek teeth, which in turn was greater than in the peripheral cement of the lower cheek teeth. However, numbers of lacunae/unit area remained similar in these 3 dentinal region. Two types of cemental hypoplasia were found in equine cheek teeth. The first type was termed central infundibular cemental hypoplasia and was confined to the central region of infundibular cement. The cement adjacent to these frequently large defects was very porous and contained large vascular channels. In recently erupted cheek teeth, these central infundibular cemental defects were filled with connective tissue. The size of these cemental defects, the relationships of such defects with the occlusal surface and the degree of porosity of cement surrounding these defects may be important in the development of cemental caries. The second type of cemental defect was found at the amelodentinal junction of both peripheral and infundibular cement and was termed junctional cemental hypoplasia and appeared as spaces varying from focal, to long narrow defects along the amelocemental junction with the adjacent cement of normal appearance.Peripheral cement was deposited both directly, i.e. on unresorbed or resorbed enamel surfaces or indirectly, where the cement was separated from enamel by a thin calcified layer. The surface of unresorbed enamel had a pitted appearance, with the bases of the pits formed by enamel prisms and the pit walls by interprismatic enamel. The cemental surface of resorbed enamel contained depressions of variable shapes and sizes. These depressions which are believed to be caused by the resorption of enamel by odontoclasts were both focal and diffuse and were more marked on the cemental surface of infundibular as compared to peripheral enamel.
A survey of reproductive performance in Thoroughbred mares and morbidity, mortality and athletic potential of their foals
Authors: MORLEY P. S. , TOWNSEND H. G. G. 
Published: April 2010

SummaryA survey was performed to evaluate the reproductive performance of Thoroughbred mares, estimate risks of dystocia and of morbidity and mortality in foals during the first yearpost partumand their physical acceptability at age one year. The study population consisted of registered Thoroughbred mares and their foals owned by residents of 4 Western Canadian provinces. Owners were identified using information obtained from the North American Jockey Club, and questionnaires were mailed regarding mares bred in 1988 and their foals born in 1989. Eighty‐three per cent of mares were reported to be pregnant at some stage following breeding, and 80% of pregnant mares subsequently gave birth to live foals. Estimates of morbidity and mortality were greater than previously reported, 25% of foals had health problems and 5% died during the first 2 weekspost partum. Twenty‐seven per cent of foals surviving 2 weeks were reportedly affected by some health problem between age 15 days and one year, and 6% died during this period. The case fatality rates of horses with upper respiratory tract infections and diarrhoea were much lower than case fatality rates for infectious diseases occurring less frequently. The rate of death or euthanasia among horses with musculoskeletal problems was relatively high after age 2 weeks. Foals with health problems up to age 2 weeks, or between age 15 days and one year were 5 to 7 times more likely to be classified as physically unacceptable for athletic use. Angular limb deformity was the health problem most commonly reported in foals receiving unacceptable physical assessments, and assessments of long‐term athletic potential were apparently not affected by the occurrence of infectious diseases.
Characterisation of equine matrix metalloproteinase 2 and 9; and identification of the cellular sources of these enzymes in joints
Authors: CLEGG P. D. , BURKE R. M. , COUGHLAN A. R. , RIGGS C. M. , CARTER S. D. 
Published: April 2010

SummaryThe cellular production by resident articular cells and infiltrating inflammatory cells of the gelatinase matrix metalloproteinases (MMP) was investigated by tissue culture methods and analysis of cell supernatants by gelatin zymography. Peripheral blood neutrophils in short term culture produced MMP‐9, as did peripheral blood monocytes in culture. Isolated articular chondrocytes in monolayer culture produced both MMP‐2 and MMP‐9, although articular cartilage maintained as explant culture produced MMP‐2 alone. Synovial fibroblasts grown in monolayer culture produced MMP‐2 alone, although synovial membrane in explant culture produced both MMP‐2 and the active form of MMP‐2. Lysis of blood polymorph neutrophils produced large quantities of MMP‐9, but lysis of blood monocytes, synovial fibroblasts and articular chondrocytes produced little enzyme indicating that, unlike the other cell types, polymorph neutrophils store MMPs intracellularly. Equine MMP‐2 was purified from synovial fibroblast cell culture supernatant, and equine MMP‐9 from polymorph neutrophil cell culture supernatant, by gelatin‐sepharose affinity chromatography. The 2 enzymes were identified from their molecular weights and by their respective N‐terminal amino acid sequences which showed homology with the enzymes from other species. The demonstration that invasive cells and resident articular cells can produce enzymes which are capable of digestion of certain component molecules of the articular cartilage matrix, shows that therapeutic targeting of these enzymes could be a valid proposition in the prevention of cartilage destruction in osteoarthritis.
Matrix metalloproteinases 2 and 9 in equine synovial fluids
Authors: CLEGG P. D. , COUGHLAN A. R. , RIGGS C. M. , CARTER S. D. 
Published: April 2010

SummaryMatrix metalloproteinases (MMPs) may be important in the destruction of cartilage seen in equine osteoarthritis and may be detectable in synovial fluid. Synovial fluids were obtained from normal equine joints and from joints of horses with aseptic and septic joint diseases. The total MMP gelatinase enzyme activities were measured by gelatin zymography and image analysis of the gels. The bioactivity of gelatinase in synovial fluid was determined by a gelatin degradation ELISA. Potential MMP‐2 & MMP‐9 monomer enzyme activities were significantly elevated in both septic and aseptic joint disease synovial fluids in comparison to fluids from normal joints. The dimer form of MMP‐9 enzyme activity was significantly elevated in fluids from septic joint disease cases in comparison to fluids from normal joints, but not fluids from horses with aseptic joint diseases. MMP‐9 monomer and dimer levels in synovial fluids correlated with the synovial fluid white blood cell count. Using the gelatin degradation ELISA to measure net active gelatinases, significant increases in gelatinase bioactivities were seen in synovial fluids from both aseptic and septic joint disease cases. The enzymes in equine joint diseases were present in a bioactive form, in that they were present in the activated form and present in excess of inhibitors, and could therefore be important in the degradation of articular cartilage in joint disease.
Cartilage canals in equine articular/epiphyseal growth cartilage and a possible association with dyschondroplasia
Authors: SHINGLETON W. D. , MACKIE ELEANOR J. , CAWSTON T. E. , JEFFCOTT L. B. 
Published: April 2010

SummaryCartilage canals have been described in most mammals and contain the vascular elements necessary for the maintenance of epiphyseal growth cartilage. The presence and longevity of cartilage canals in developing articular/epiphyseal cartilage of horses is described for the first time. Growth cartilages from 30 normal horses (from 130 days gestation to age 2 years) and 6 cases of dyschondroplasia (age <15 months) were examined. Cartilage canals were located in the epiphyses of fetuses as early as 130 days gestation. The secondary centres of ossification had developed by 250 days gestation and, at full term (∼340 days), the articular/epiphyseal cartilage was highly vascularised. Cartilage canals were closely surrounded by small round chondrocytes even when present in the zone of hypertrophic chondrocytes. From late gestation until at least age 10 weeks, blood vessels surrounded by cartilage were found extending beyond the zone of hypertrophic chondrocytes into the secondary centre of ossification. Cartilage canals were absent from normal articular/epiphyseal cartilage of animals age >6 months. Cartilage canals were associated with retained cartilage of dyschondroplastic lesions found in animals age < 15 months. The presence of cartilage canals in association with dyschondroplastic lesions suggests they may have a role in the pathogenesis of this important disease.
Effect of high volume epidural morphine, ketamine and butorphanol on halothane minimum alveolar concentration in ponies
Authors: DOHERTY T. J. , GEISER D. R. , ROHRBACH B. W. 
Published: April 2010

SummaryThis study determined the effects of epidurally administered morphine, ketamine and butorphanol on halothane minimum alveolar concentration (MAC) in ponies. Seven ponies were anaesthetised with thiopentone and succinylcholine, intubated and anaesthesia maintained with halothane. Ventilation was controlled and blood pressure was maintained within normal limits. Following the determination of baseline halothane MAC for the pelvic and thoracic limbs the ponies were given morphine (0.1 mg/kg bwt), ketamine (0.8 or 1.2 mg/kg bwt), butorphanol (0.05 mg/kg bwt) or saline, epidurally, to a final volume of 0.15 ml/kg bwt. The halothane MAC for the pelvic and thoracic limbs was redetermined following each treatment. The baseline halothane MAC for the control group was mean ± s.e. 0.85 ± 0.02% and no significant change occurred after saline administration. Morphine significantly (P = 0.002) decreased MAC from, mean ± s.e. 0.90 ± 0.05% to 0.77 ± 0.06% in the pelvic limb. Ketamine significantly decreased MAC in the pelvic limb from mean ± s.e. 0.86 ± 0.06% to 0.71 ± 0.04%, and 0.82 ± 0.03% to 0.71 ± 0.02%, for the low (P = 0.008) and high dose (P = 0.001), respectively. No significant change in MAC occurred following butorphanol. No treatment reduced halothane MAC for the thoracic limb.
A scoring system for gastric ulcers in the horse
Authors: MACALLISTER C. G. , ANDREWS F. M. , DEEGAN E. , RUOFF W. , OLOVSON S.‐G. 
Published: April 2010

SummaryFive investigators familiar with gastric ulcer disease in horses met to establish a scoring system that could be utilised in future studies. Slides of gastric lesions were viewed and discussed and a scoring system established that required the nonglandular and glandular portions of the stomach to be graded separately. Each portion of the stomach (glandular and nonglandular) received a score for number of ulcers present and a score for severity of ulcers which resulted in each stomach receiving 4 separate scores. After the grading system was developed, each investigator independently graded 16 horses with gastric ulcer disease that had been previously recorded on video tape. The results of each investigator's scores were then compared. There was a variability between observers in the scores for severity of both nonglandular and glandular lesions but the variability was not significant The variability between observers for the number of glandular lesions was also not significant. This implied that there was consistency between the 5 observers in the way severity of lesions was scored and the number of glandular lesions. However, there was a significant variability between observers for the number of nonglandular lesions which implied agreement on this observation was more variable.
Effects of insulin and insulin‐like growth factors I and II on the growth of equine fetal and neonatal chondrocytes
Authors: HENSON FRANCES M. D. , DAVENPORT CELIA , BUTLER LINDA , MORAN I. , SHINGLETON W. D. , JEFFCOTT L. B. , SCHOFIELD P. N. 
Published: April 2010

SummaryThe effects of insulin and insulin‐like growth factors (IGFs) I and II on fetal and foal chondrocytes were investigated in vitro. Chondrocytes from the lateral trochlear ridge of the distal femur were obtained from 2 fetuses (280 and 320 days gestation) and one 4‐day‐old foal and cultured. Membrane proteins consistent with type 1 and type 2 IGF receptors were demonstrated by radioligand cross linking and equilibrium binding analysis. It was demonstrated that both IGF‐I and IGF‐II acted as mitogens for isolated equine chondrocytes when present as the sole mitogenic factor in monolayer culture. It was further shown that whereas insulin was able to promote the survival and expansion of cell populations of chondrocytes in culture there was significantly reduced mitogenic stimulation compared to the IGFs. These results suggest that the role of insulin in growth cartilage may be to promote chondrocyte survival, or to suppress differentiation/apoptosis. This supports the hypothesis that relative hyperinsulinaemia may be a contributory factor to equine dyschondroplasia (osteochondrosis). Understanding of contributory, and possibly triggering factors such as this may allow the development of modified methods of husbandry which minimise the risk of disease in populations with a known predisposition.
Severe mitral regurgitation in horses: clinical, echocardiographic and pathological findings
Authors: REEF VIRGINIA B. , BAIN F. T. , SPENCER PAMELA A. 
Published: April 2010

SummaryForty‐three horses with mitral regurgitation (MR) and congestive heart failure were examined, using M‐mode, 2‐dimensional real‐time and Doppler echocardiography. There was no breed or sex predisposition when compared to the general hospital population. The mean ± s.d. age of affected horses was 7.6 ±8.1 years. Horses with MR and congestive heart failure had significant increases in mean values for left ventricular chamber size, left atrial size and heart rate and significant decreases in interventricular septal and left ventricular free wall thickness. Significant increases in pulmonary artery diameter were detected compared to aortic diameter. Mean values for fractional shortening were not significantly different from normal.All horses had aGrade 3–6/6holosystolic or pansystolic murmur with its point of maximal intensity in the mitral to aortic valve area. Atrial fibrillation was found at presentation in 24 horses with MR and congestive heart failure. One horse presented with atrial tachycardia and subsequently developed atrial fibrillation. Seven horses had ventricular premature contractions. Exercise intolerance (n = 34), respiratory signs (n = 31), and fever (n = 21) were the most common presenting signs. Thickening of the left atrioventricular valve leaflets, endocarditis, flail valve leaflets, rupture of achorda tendineae, and mitral valve prolapse were detected echocardiographically. Doppler echocardiography confirmed the presence of a large systolic regurgitant jet in the left atrium in all horses in which it was used, and in many horses, concurrent tricuspid and pulmonary regurgitation was detected. All horses died or were subjected to euthanasia due to the severity of their MR and/or lack of response to therapy.Post mortemexaminations were performed in 35 horses and confirmed the echocardiographic findings. The echocardiographic detection of a flail mitral valve leaflet was significantly associated with the detection of a rupturedchorda tendineaeatpost mortemexamination. There was a significant association between echocardiographic detection of a dilated pulmonary artery and its presence atpost mortemexamination.M‐mode, 2‐dimensional real‐time, and Doppler echocardiography should be used to accurately characterise the valvular abnormalities and assess the severity of mitral regurgitation. Pulmonary artery dilatation, an echocardiographic indication of severe pulmonary hypertension, should be considered a grave prognostic indicator and may indicate impending pulmonary artery rupture.
Post exercise changes in compartimentai body temperature accompanying intermittent cold water cooling in the hyperthermic horse
Authors: MARLIN D. J. , SCOTT CAROLINE M. , ROBERTS C. A. , CASAS I. , HOLAH G. , SCHROTER R. C. 
Published: April 2010

SummaryWhereas the efficacy of cold water cooling of horses has been demonstrated by several studies, the dynamics of temperature changes within and between compartments (primarily muscle, blood [core], skin and deep core [rectal]) have not been investigated. Changes in body temperature associated with cold water cooling were investigated in the hyperthermic horse. Muscle (TMU), pulmonary artery (TPA), rectal (TREC), tail‐skin (TTSK) and coat surface (TCOAT) temperatures, were monitored continuously in 5 Thoroughbred horses during and after exercise in hot humid (30°C and 80% RH) conditions on a treadmill. Horses were cooled in the hot humid environment with cold water (∼6°C) for 6 30 s periods. Between each 30 s cooling period the horses stood for 30 s. A total of 180 1 of cold water was applied. Horses were monitored for a further 4 min following the final cooling period. From the end of exercise to the end of the final cooling (6.5 min), mean (± s.e.) rates of decrease for TTSK and TPA were similar (0.8 ± 0.1 and 0.8 ± 0.1°C/min, respectively). The effects on TMU and TREC were less marked, with average rates of 0.2 ± 0.1 and 0.0 ± 0.1°C/min, respectively. During the first 4 min of cooling, TPA fell during the 30 s period of water application and rose during each 30 s period of standing. When TPA fell below ∼36.5°C, these variations were suppressed and TPA rose steadily, despite continued applications; TREC and TMU continued to fall, although less rapidly than before. These observations are consistent with the onset of skin vasoconstriction at low TPA. The mechanism is mediated through a cooling of circulating blood volume providing a greater capacity for heat transfer between muscle and circulation. Intermittent application of cold water (∼6°C) improves heat removal without apparent deleterious effects and is well tolerated. Even when hypothermia develops (based on TPA), muscle and rectal temperatures continue to fall.
Effects of osteochondral fragmentation and intra‐articular triamcinolone acetonide treatment on subchondral bone in the equine carpus
Authors: KAWCAK C. E. , NORRDIN R. W. , FRISBIE D. D. , TROTTER G. W. , MCILWRAITH C. W. 
Published: April 2010

SummaryTo determine the effects of osteochondral fragmentation and intra‐articular corticosteroid treatment on dynamics of bone remodelling and fragility, 12 horses each had a unilateral, 8 mm osteochondral fragment created in the distal aspect of one radiocarpal bone. Six of the horses were treated in the fragmented joint, and the other 6 were treated in the nonfragmented joint with 12 mg of triamcinolone acetonide (TA) 14 and 28 days after surgery. All horses were exercised on a high‐speed treadmill starting 15 days, and ending 72 days after surgery. Horses treated with TA in the fragmented joints were significantly less lame than those treated in the nonfragmented joints. Third carpal bones from joints with fragments showed significantly more vascularity, single labelled surface, total labelled surface and mineralising surface in subchondral and subjacent trabecular bone. Trends were also seen towards higher vascular canal volume and osteochondral junction remodelling sites in third carpal bones from fragmented joints. No significant differences were seen in microdamage density or size between fragmented and nonfragmented joints. No significant influence of TA treatment was seen on any parameter measured. The results from this study show that osteochondral fragmentation induces significant changes in remodelling of opposing bones, and that the administration of corticosteroids into joints with fragmentation does not significantly alter bone remodelling or fragility.
Effect of exercise on erythrocyte β‐adrenergic receptors and plasma concentrations of catecholamines and thyroid hormones in Thoroughbred horses
Authors: GONZÁLEZ O. , GONZÁLEZ EMA , SÁNCHEZ C. , PINTO J. , GONZÁLEZ I. , ENRÍQUEZ O. , MARTÍNEZ R. , FILGUEIRA G. , WHITE A. 
Published: April 2010

SummaryThe effects of exercise stress on erythrocyte β‐adrenergic receptor characteristics and plasma concentrations of adrenaline, noradrenaline and thyroid hormones were studied in Thoroughbred racehorses during rest and after exercise.Five minutes after a maximal speed race of 1200 ± 200 m (mean ± s.d.), both plasma adrenaline and noradrenaline concentrations increased with respect to basal values (from 2.48 ± 0.15 to 3.83 ± 0.27 and from 2.13 ± 0.11 to 3.53 ± 0.27 nmol/1 respectively). The increment of adrenaline was greater in high performance (HP) as compared to low performance (LP) horses (76.9 vs. 43.5%), in accordance with the contribution of the adrenal medulla in the sympathoadrenal response to exercise.Triiodothyronine (T3), but not thyroxine (T4) levels increased 5 min after exercise (from 55.6 ± 2.9 to 81 ± 3.7 ng/dl and from 0.67 ± 0.04 to 0.70 ± 0.05 pg/dl respectively). No differences were observed in basal values of thyroid hormones or in the percentage of T3 increment, when comparing HP vs. LP horses.Erythrocyte membranes obtained 5 min after racing showed decreased concentrations of β‐adrenergic receptors (β‐AR) and dissociation constant as compared to basal values (50.1 ± 7.0 vs. 95.7 ± 12.0 fmol/mg protein and 0.97 ± 0.24 vs. 2.04 ± 0.3 nmol/l respectively). This temporal pattern suggest that the observed changes in β‐AR characteristics could be mediated by catecholamines, but not by thyroid hormones, in this model. This down regulation of β‐AR may act as a protecting mechanism preventing the erythrocytes from the decrease in membrane fluidity known to be provoked by adrenergic agonists.The accomplished study showed that, in the Thoroughbred horse, there is a homeostatic response to race stress, characterised by a sudden increase in plasma catecholamines and T3 and a parallel decrease in β‐AR concentration on the erythrocyte membrane. In this way the racing horse could rapidly adjust its metabolism to the exercise stress, but at the same time override one possible undesirable side‐effect caused by these hormonal changes. Further studies will be required to establish performance‐related differences occurring in endocrine changes.