A Comparison of Positive Reinforcement Training Techniques in Owl and Squirrel Monkeys: Time Required to Train to Reliability

This study compared the physiological response to novel situations in sex-separated and sex-mixed groups of horses, as measured by heart rate (HR). The study evaluated the possibility of training horses in a mixed-sex system. The study included 41 Purebred Arabian 2½-year-olds during their first walk on an automated horse walker. Four groups, divided by manner of care and training, consisted of 10 colts and 10 fillies kept in separate stables and trained in separate male or female groups and 12 colts and 9 fillies kept in the same stable and trained together. The study measured HR when horses were at rest before exercise, while moving from stable to walker, during 30 min of exercise on walker, while moving from walker to stable, and at rest after exercise. Mean HR scores recorded from training on the walker were higher in sex-mixed groups. Results obtained while horses were moving from stable to walker, then from walker to stable, were significantly higher in the sex-mixed groups. The study did not recommend training young horses in sex-mixed groups.     

Is it a good idea to train fillies and colts separately?

This study compared the physiological response to novel situations in sex-separated and sex-mixed groups of horses, as measured by heart rate (HR). The study evaluated the possibility of training horses in a mixed-sex system. The study included 41 Purebred Arabian 2?-year-olds during their first walk on an automated horse walker. Four groups, divided by manner of care and training, consisted of 10 colts and 10 fillies kept in separate stables and trained in separate male or female groups and 12 colts and 9 fillies kept in the same stable and trained together. The study measured HR when horses were at rest before exercise, while moving from stable to walker, during 30 min of exercise on walker, while moving from walker to stable, and at rest after exercise. Mean HR scores recorded from training on the walker were higher in sex-mixed groups. Results obtained while horses were moving from stable to walker, then from walker to stable, were significantly higher in the sex-mixed groups. The study did not recommend training young horses in sex-mixed groups.     

How does exercise intensity and type affect equine distal tarsal subchondral bone thickness?

Adaptation of osteochondral tissues is based on the strains experienced during exercise at each location within the joint. Different exercise intensities and types may induce particular site-specific strains, influencing osteochondral adaptation and potentially predisposing to injury. Our hypotheses were that patterns of equine distal tarsal subchondral bone (SCB) thickness relate to the type and intensity of exercise, and that high-intensity exercise leads to site-specific increases in thickness. SCB thickness was measured at defined dorsal and plantar locations on magnetic resonance images of cadaver tarsi collected from horses with a history of low [general purpose (n=20) and horse walker (n=6)] or high [elite competition (n=12), race training (n=15), and treadmill training (n=4)] exercise intensity. SCB thickness was compared between sites within each exercise group and between exercise groups. SCB thickness in elite competition and race training, but not treadmill training, was greater than low-intensity exercise. For general purpose horses, lateral SCB thickness was greater than medial throughout. Horse walker exercise led to relatively thicker lateral and medial SCB compared with the midline. Elite competition was associated with increased SCB thickness of the proximal small tarsal bones medially and the distal bones laterally. For race training and treadmill training, there were minimal differences between sites overall, although the lateral aspect was greater than medial, and medial greater than midline at a few sites for race training. In conclusion, different types of high-intensity exercise were associated with different patterns of SCB thickness across the joints from medial to lateral and proximal to distal, indicating that both exercise intensity and type of exercise affect the SCB response at any particular site within the equine distal tarsal joints.     

Blood circulation of long bones in trained growing rats and mice.

The effect of physical training on the blood circulation of long bones was studied in growing rats and mice of NMRI-strain. The animals to be trained and their controls were about 2 weeks old at the beginning of the training. The training took place on a 5 degree inclined treadmill 5 days a week for 3 weeks in experiment I and 7 weeks in experiments II and III. The duration of the daily exercise was progressively increased over 3 weeks. The final exercise bouts were 80 min for moderate and 180 min for intensive training programs. The circulating red cell volume (ml/100 g bone) of the humeral, femoral and tibial bones of the trained animals was lower compared to the controls in all three experiments mainly due to reduced hematocrit values. The circulating blood volume (ml/100 g bone) decreased in the tibial bones of the trained animals in experiment I and showed a decreasing tendency in experiment III, but no significant differences between the groups were observed in the humeral and femoral bones. Yet, when related to the volume of the bones the circulating blood volume (ml/100 ccm bone) was significantly higher in the femoral bones of the trained animals, while the changes in the humeral bones were negligible (experiment III). The results suggest that the vascularity of long bones is affected by physical training. The varying responses in different bones are perhaps due to the amount of mechanical stress during physical activity.     

In vivo determination of normal and anterior cruciate ligament-deficient knee kinematics

The objective of the current study was to use fluoroscopy to accurately determine the three-dimensional (3D), in vivo, weight-bearing kinematics of 10 normal and five anterior cruciate ligament deficient (ACLD) knees. Patient-specific bone models were derived from computed tomography (CT) data. 3D computer bone models of each subject's femur, tibia, and fibula were recreated from the CT 3D bone density data. Using a model-based 3D-to-2D imaging technique registered CT images were precisely fit onto fluoroscopic images, the full six degrees of freedom motion of the bones was measured from the images. The computer-generated 3D models of each subject's femur and tibia were precisely registered to the 2D digital fluoroscopic images using an optimization algorithm that automatically adjusts the pose of the model at various flexion/extension angles. Each subject performed a weight-bearing deep knee bend while under dynamic fluoroscopic surveillance. All 10 normal knees experienced posterior femoral translation of the lateral condyle and minimal change in position of the medial condyle with progressive knee flexion. The average amount of posterior femoral translation of the lateral condyle was 21.07 mm, whereas the average medial condyle translation was 1.94 mm, in the posterior direction. In contrast, all five ACLD knees experienced considerable change in the position of the medial condyle. The average amount of posterior femoral translation of the lateral condyle was 17.00 mm, while the medial condyle translation was 4.65 mm, in the posterior direction. In addition, the helical axis of motion was determined between maximum flexion and extension. A considerable difference was found between the center of rotation locations of the normal and ACLD subjects, with ACLD subjects exhibiting substantially higher variance in kinematic patterns.     

Sclerosis of the Third Carpal Bone

To assess the significance of radiographic signs of sclerosis of the third carpal bone (C3) in young Standardbred trotters in relation to performance, lameness and bone turnover both carpi in 14 Standardbred trotters were radiographically and scintigraphically examined 6 times, from the beginning of speed training until the beginning of racing, between the mean ages of 20 and 42 months. At the end of the study 8 horses had raced in official qualifying races and 14 limbs in 11 horses had been diagnosed with carpal lameness. All horses but 2 developed sclerosis and all but one had increased bone turnover in the C3 area by scintigraphy. C3 sclerosis increased continuously over time and with increased performance. Carpal lameness was significantly associated with progression of sclerosis but in most cases sclerosis developed without concomitant signs of carpal lameness. No association between carpal lameness and increased scintigraphic uptake was found, but horses that had qualified for racing had significantly higher C3 to carpus ratio of radiopharmaceutical uptake. We conclude that there is a continuous increase in C3 radiographic sclerosis with time in young Standardbred trotters in professional training, but radiographic sclerosis appears to be of limited value as an indicator of clinical carpal disease or level of performance in Standardbred trotters.     

Effect of magnesium supplementation and training on magnesium tissue distribution in rats

The aim of this work is to study the effect of training and Mg supplementation on body pools of Mg and on Mg tissue distribution. Forty male Wistar rats were divided into four groups (n=10): control group (C); trained group (T); Mg-supplemented group (+Mg); and trained and Mg-supplemented group (+MgT). The Mg supplement (100 ppm of Mg) was given in the drinking water for 21 d. The training consisted of swimming during 60% of maximal swimming time obtained in the first session to exhaustion, during 3 wk (5 d a week). The variables measured were: erythrocytes (RBC), hemoglobin (Hb), hematocrit (Hto), total proteins (TP), and Mg in serum, RBC, liver, muscle, bone, and kidney. There was less Mg in liver, muscle, and erythrocyte in trained animals than in control or supplemented animals (T vs C, +MgT vs C and +MgT vs +Mg) (p < 0.01). Trained antimals (T and +MgT) showed higher Mg kidney rates than the untrained ones (p<0.01). There was less bone Mg in control (C) and in supplemented and trained (+MgT) groups than in trained (T) and in supplemented (+Mg) animals (p<0.01). Serum Mg showed a decreasing concentration profile in the following order: +Mg, +MgT, T, C (p<0.01). We conclude that Mg supplementation improves bone and serum Mg levels, but this does not affect Mg status in soft tissues. Maintained exercise leads to a diminution of Mg in the aforementioned soft tissues that is not noticeable in serum, probably provoked by an increase of renal excretion.     

Evidence for the effect of serotonin receptor 1A gene (HTR1A) polymorphism on tractability in Thoroughbred horses

Tractability, or how easily animals can be trained and controlled, is an important behavioural trait for the management and training of domestic animals, but its genetic basis remains unclear. Polymorphisms in the serotonin receptor 1A gene (HTR1A) have been associated with individual variability in anxiety‐related traits in several species. In this study, we examined the association between HTR1A polymorphisms and tractability in Thoroughbred horses. We assessed the tractability of 167 one‐year‐old horses reared at a training centre for racehorses using a questionnaire consisting of 17 items. A principal components analysis of answers contracted the data to five principal component (PC) scores. We genotyped two non‐synonymous single nucleotide polymorphisms (SNPs) in the horse HTR1A coding region. We found that one of the two SNPs, c.709G>A, which causes an amino acid change at the intracellular region of the receptor, was significantly associated with scores of four of five PCs in fillies (all Ps < 0.05) and one PC in colts (P < 0.01). Horses carrying an A allele at c.709G>A showed lower tractability. This result provides the first evidence that a polymorphism in a serotonin‐related gene may affect tractability in horses with the effect partially different depending on sex.     

Morphometrical studies of human femoral condyles

Thirty-six cadaver knees were examined by various morphometrical methods in order to obtain mathematical and graphical data concerning the geometry of the lower end of the femora. It was found that the paramedian sagittal curves represented magnifications of a certain curvalure pattern specific to the medial and the lateral femoral condyle. These curves could be expressed mathematically for each condyle. Furthermore, we found dimensional as well as geometrical intervariations between the different size groups in the knee sample. This could serve as an argument for preferring a different design for medial and lateral condyle components in knee prostheses.     

The effect of breed-type and castration on bone growth and distribution in cattle.

Data from carcasses of 210 cattle (119 bulls and 91 steers) from 4 breed types, serially slaughtered from approximately 200-800 kg kg liveweight were used to test the hypothesis of similar gender dimorphism among breeds in relation to carcass bone growth and distribution. Relative to total bone weight, breed types tended to have similar growth rates for all bones other than the cervical vertebrae, ribs, tibia and fibula, and tarsus. Adjusted to the same total bone weight there were significant differences among breed types in bone weight distribution, but the differences were very small and probably of little economic importance. Castration stimulated growth of the lumbar vertebrae, hindlimb bones, patella and hindquarter bones but inhibited growth of the ribs, scapula, carpus, forelimb bone, and forequarter bone. At the same total bone weight, steers as compared to bulls showed a shift in bone weight distribution towards the hindquarter, pistol and long bones. There were small but significant breed x gender interactions in the distribution of some bones.     

The variation of the cross-sectional shape in the long bones of birds and mammals

The transverse and sagittal diameters of the long bones were measured in a sample of 53 species of eutherian mammals and 36 species of birds. The scaling of the transverse and sagittal diameters of each bone to body mass was calculated. For each bone the ratio of sagittal/transverse diameter was calculated, as an expression of the cross-sectional shape of the bones. The distributions of the ratios were not significantly different from normality in all the avian bones and in the mammalian femur and tibia. In most cases, the mean of the distribution was significantly different from 1 (circular shape). The analysis shows that changes in the ratio can be caused by selective factors, considering the correlation predicted between the breaking moments and the radii, but at the same time the cross-sectional shape of mammalian and avian long bones may have a phylogenetic basis. Finally, the previous assumption of relationship between bone curvature and stress predictability, is also discussed.     

Tibiofemoral kinematics and condylar motion during the stance phase of gait

Accurate knowledge of the dynamic knee motion in-vivo is instrumental for understanding normal and pathological function of the knee joint. However, interpreting motion of the knee joint during gait in other than the sagittal plane remains controversial. In this study, we utilized the dual fluoroscopic imaging technique to investigate the six-degree-of-freedom kinematics and condylar motion of the knee during the stance phase of treadmill gait in eight healthy volunteers at a speed of 0.67 m/s. We hypothesized that the 6DOF knee kinematics measured during gait will be different from those reported for non-weightbearing activities, especially with regards to the phenomenon of femoral rollback. In addition, we hypothesized that motion of the medial femoral condyle in the transverse plane is greater than that of the lateral femoral condyle during the stance phase of treadmill gait. The rotational motion and the anterior–posterior translation of the femur with respect to the tibia showed a clear relationship with the flexion–extension path of the knee during the stance phase. Additionally, we observed that the phenomenon of femoral rollback was reversed, with the femur noted to move posteriorly with extension and anteriorly with flexion. Furthermore, we noted that motion of the medial femoral condyle in the transverse plane was greater than that of the lateral femoral condyle during the stance phase of gait (17.4±2.0 mm vs. 7.4±6.1 mm, respectively; p<0.01). The trend was opposite to what has been observed during non-weightbearing flexion or single-leg lunge in previous studies. These data provide baseline knowledge for the understanding of normal physiology and for the analysis of pathological function of the knee joint during walking. These findings further demonstrate that knee kinematics is activity-dependent and motion patterns of one activity (non-weightbearing flexion or lunge) cannot be generalized to interpret a different one (gait).     

Carnosine content of the middle gluteal muscle in thoroughbred horses with relation to age, sex and training

1. Muscle biopsies were collected from 85 thoroughbred horses and analysed for carnosine content by an automated HPLC method. 2. No significant sex difference was found between colts, geldings and fillies. 3. There was a trend towards lower muscle carnosine contents with age, which was only significant between 1-year-old untrained horses and 4+ year-old horses (P less than 0.002).     

Differential response of rat limb bones to strenuous exercise

We examined the influence of a strenuous exercise regimen on tibial and metatarsal bones to show not only how the geometric, histological, and mechanical properties of immature bone respond to strenuous exercise but also how long bones within the same limb may respond differentially to exercise. Female Sprague-Dawley rats (8 wk old) were divided randomly into two groups: a sedentary control (n = 15) and an exercised group (n = 15). The exercise intensity was 80-90% of maximum oxygen capacity 5 days/wk for 10 wk. Mechanical properties of tibia and second metatarsus (MT) were determined with three-point bending, and contralateral bones were used for geometric and histological analyses. Length and middiaphyseal cross-sectional geometry of the exercised tibiae were significantly less than controls, but material properties were not different. The exercised tibiae had significantly lower structural properties (e.g., loads at the proportional limit and maximum and energy at failure load). The middiaphyseal dorsal cortex of exercised MT was significantly thicker than controls, but tensile stress at the proportional limit and elastic modulus of exercised MT were significantly less than controls. The average number of osteons and osteocytes per unit area of the tibial middiaphysis was significantly greater in the exercised group--especially in lateral and posterior cortices. The number of osteons and osteocytes per unit area in the MT, however, was significantly less in the exercised group. The differential effects of strenuous exercise on tibia and MT suggest that local loading and bone-specific responses have important roles in modulating the response of immature bone to strenuous exercise.     

Fetlock joint kinematics differ with age in Thoroughbred [was thoroughbred] racehorses

Fetlock joint kinematics during galloping in 2-, 3-, 4-, and 5-year-old Thoroughbreds in race training were quantified to determine if differences due to age could account for the observation that 2-year old Thoroughbred racehorses incur a high number of injuries to the bones and soft tissues in the distal forelimbs during training and at the outset of racing. Twelve Thoroughbred racehorses were videotaped in the sagittal plane at 250 frames/s during their daily galloping workout on a 7/8 mile sand-surface training track. Four galloping strides were recorded for each horse and subsequently digitized to determine fetlock joint angles of the leading forelimb during the limb support period of a stride. Four kinematic variables were measured from each stride's angular profile: angle of fetlock joint dorsi-flexion at mid-stance, negative angular velocity, positive angular velocity and time from hoof impact to mid-stance phase of limb support. The 2-year old Thoroughbreds had significantly quicker rates of dorsi-flexion of their fetlock joints than 3- (p=0.01), 4- (p=0.01), and 5-year old (p<0.01) Thoroughbreds following impact of the leading forelimb during moderate galloping (avg. 14 m/s). Higher rates of dorsi-flexion in young Thoroughbreds may reflect immaturity (lack of stiffness) of the suspensory apparatus tissues.     

Mechanical assessment of effects of grape seed proanthocyanidins extract on tibial bone diaphysis in rats

We studied the effects of grape seed proanthocyanidins extract (GSPE) given as a ratio of 3 mg in 100 g in a standard diet, on the tibial bone diaphysis in low-calcium fed rats. Measurements of bone density, mineral content, geometry, and bone strength using peripheral quantitative computed tomography (pQCT). Further, the whole tibia bones were tested for mechanical resistance using a material-testing machine, and mineral elements were also determined. Forty male Wistar rats, 5 weeks old, were divided into control (Co), low-calcium diet (LC), low-calcium diet . standard diet (LCS), and low-calcium diet . standard diet with supplementary GSPE (LCSG) groups. We found no significant differences in body weight among the 4 groups, whereas all of the bone parameters in LC were significantly lower than those in Co (p<0.01, except in periosteal perimeter (Peri) p<0.05). The cortical bone mineral content (CtBMC), cortical bone density (CtvBMD) and Peri in LCSG were significantly higher than those in LCS (p<0.01; p<0.01; p<0.05, respectively). All bone parameters in LCSG were significantly higher than those in LC (p<0.01, except in Peri, and stress strain index to reference axis x (xSSI) p<0.05)). In addition, Ca, P, and Zn contents in LCSG were significantly higher than those in LCS (p<0.01; p<0.01; p<0.05, respectively). Our results suggest that GSPE included in a diet mixture with calcium has a beneficial effect on bone formation and bone strength for the treatment of bone debility caused by a low level of calcium.     

The evaluation of knee bone mineral density following open-wedge high tibial osteotomy

Examinations of bone density changes in selected knee bone ends were evaluated prospectively in a randomized group of 28 patients, aged from 41 to 65 (mean: 55.3 years), who had varus deformations of their mechanic limb axes, mean 8 degrees. The examinations were conducted during the preoperative period, 10 days, 3, 6, and 12 weeks, as well as 6 and 12 months after the procedure. A statistically significant increase in bone density was observed in the medial tibial condyle area, while a statistically insignificant decrease of bone density was noted in the medial femoral condyles. Bone density increased in the lateral tibial condyle area, whereas there were no density changes in the area of the lateral femoral condyles. The research results demonstrate that the relief achieved in ailments after high tibial osteotomies does not directly correspond to the bone density of the affected areas.     

A nonnatural head-neck position (Rollkur) during training results in less acute stress in elite, trained, dressage horses

This study measured parameters of stress in recreational, trained horses (REC; n = 7) and elite (International Grand Prix level) trained, dressage horses (DRES; n = 5). The training of the DRES horses uses an unnatural head-neck position (Rollkur), whereas in the REC horses such training techniques are not common. The study measured stress by using heart rate variability analysis for 30 min postfeeding in the morning and 30 min postexercise after a morning training session. The study found no significant difference at rest between the REC and DRES horses. During the posttraining measurements, however, the DRES horses showed, among others, a less sympathetic and increased parasympathetic dominance. These results suggest that DRES horses tend to have less acute stress than do REC horses postexercise. The findings of this study suggest maintaining the health and well-being of DRES horses despite nonnatural, biomechanical positions.     

Melanocortin 1 Receptor-Signaling Deficiency Results in an Articular Cartilage Phenotype and Accelerates Pathogenesis of Surgically Induced Murine Osteoarthritis

Proopiomelanocortin-derived peptides exert pleiotropic effects via binding to melanocortin receptors (MCR). MCR-subtypes have been detected in cartilage and bone and mediate an increasing number of effects in diathrodial joints. This study aims to determine the role of MC1-receptors (MC1) in joint physiology and pathogenesis of osteoarthritis (OA) using MC1-signaling deficient mice (Mc1re/e). OA was surgically induced in Mc1re/e and wild-type (WT) mice by transection of the medial meniscotibial ligament. Histomorphometry of Safranin O stained articular cartilage was performed with non-operated controls (11 weeks and 6 months) and 4/8 weeks past surgery. µCT–analysis for assessing epiphyseal bone architecture was performed as a longitudinal study at 4/8 weeks after OA-induction. Collagen II, ICAM-1 and MC1 expression was analysed by immunohistochemistry. Mc1re/e mice display less Safranin O and collagen II stained articular cartilage area compared to WT prior to OA-induction without signs of spontaneous cartilage surface erosion. This MC1-signaling deficiency related cartilage phenotype persisted in 6 month animals. At 4/8 weeks after OA-induction cartilage erosions were increased in Mc1re/e knees paralleled by weaker collagen II staining. Prior to OA-induction, Mc1re/e mice do not differ from WT with respect to bone parameters. During OA, Mc1re/e mice developed more osteophytes and had higher epiphyseal bone density and mass. Trabecular thickness was increased while concomitantly trabecular separation was decreased in Mc1re/e mice. Numbers of ICAM-positive chondrocytes were equal in non-operated 11 weeks Mc1re/e and WT whereas number of positive chondrocytes decreased during OA-progression. Unchallenged Mc1re/e mice display smaller articular cartilage covered area without OA-related surface erosions indicating that MC1-signaling is critical for proper cartilage matrix integrity and formation. When challenged with OA, Mc1re/e mice develop a more severe OA-pathology. Our data suggest that MC1-signaling protects against cartilage degradation and subchondral bone sclerosis in OA indicating a beneficial role of the POMC system in joint pathophysiology.