The effect of aerobic exercise after a period of inactivity on bone remodeling and calcium and phosphorus balance in mature horses

An experiment was conducted to determine the effect of aerobic training after a sedentary period on bone remodeling and Ca and P balance and serum concentrations in varying ages of mature horses. Eighteen stock-type geldings were blocked into three age groups (6 to 10, 11 to 15, and 16 and older years of age), within two groups of nine, with horses randomly assigned to one of two exercise treatments, exercised for 112 days (control) or idle for 56 days followed by 56 days of exercise (treated). Blood samples were taken at the beginning of period I and at 14-day intervals thereafter to determine serum concentrations of osteocalcin (OST), Ca, and P. Dorsal-palmar and lateral-medial radiographs were taken of the left third metacarpal bone on days 0, 56, 84, and 112 to monitor changes in bone density. Total fecal and urine collections were taken for 72 hours on days 0, 56, and 112. Mean serum OST concentrations were affected by treatment (P<.02), time (P<.001); and the interactions of treatment and age (P<.003), time and treatment (P<.001), and time, treatment, and age (P<.001). Overall dorsal (DBRAE), palmar (PRBAE), and medial (MRBAE) RBAE means were affected by time (P<.001), as was overall lateral (LRBAE) RBAE mean (P<.005). Overall DBRAE and PRBAE means were lower (P<.04) at day 56, and higher at day 84 (P<.02) and 112 (P<.001) as compared to day 0. Mean serum Ca concentration was affected by treatment (P<.003) and time (P<.001). Mean serum P concentration was affected by the interaction of time and treatment (P<.001). Mean apparent daily Ca balance was affected bythe interaction of time, treatment, and age (P<.03). Mean apparent daily P balance was affected by treatment (P<.02) and time (P<.001). Biochemical and radiographic data from this experiment suggest that bone remodeling as well as Ca and P balance and serum concentrations are affected by age, inactivity, and exercise in mature horses.     

Immunolocalization of Melatonin and Follicle‐Stimulating Hormone Receptors in Caprine Ovaries and their Effects During in vitro Development of Isolated Pre‐Antral Follicles

The expression of melatonin type 1 (MT1) and FSH (FSHR) receptors in caprine ovaries and the effects of these hormones on the in vitro development of isolated pre‐antral follicles were evaluated. Follicles (≤200 μm) were cultured for 12 days in α‐MEM (control) or melatonin (100 or 1000 pg/ml) or sequential melatonin medium (100 pg/ml: from day 0 to day 6; 1000 pg/ml: from day 6 to day 12; experiment 1) and in control or sequential FSH (100 ng/ml from day 0 to day 6; 500 ng/ml from day 6 to day 12) or sequential melatonin or this latter plus sequential FSH (experiment 2). MT1 and FSHR expressions were observed in granulosa cells from secondary and antral follicles. The oocytes from primordial and primary follicles also express FSHR. Sequential melatonin increased the percentage of normal follicles and oocyte recovery compared with the control or melatonin (1000 pg/ml) at day 12. In experiment 2, all the treatments increased the normal follicles and growth compared with the control. In conclusion, this study demonstrated the presence of MT1 and FSHR in caprine ovaries. The addition of increased concentrations of melatonin (sequential medium) or FSH can be used to promote the in vitro development of caprine pre‐antral follicles.     

Effect of Physiologically Relevant Heat Shock on Development,Apoptosis and Expression of Some Genes in Buffalo (Bubalus bubalis) Embryos Produced In Vitro

For investigating the effects of physiologically relevant heat shock, buffalo oocytes/embryos were cultured at 38.5°C (control) or were exposed to 39.5°C (Group II) or 40.5°C (Group III) for 2 h once every day throughout in vitro maturation (IVM), fertilization (IVF) and culture (IVC). Percentage of oocytes that developed to 8‐cell, 16‐cell or blastocyst stage was lower (p < 0.05) and the number of apoptotic nuclei was higher (p < 0.05) for Group III > Group II > controls. At both 8–16‐cell and blastocyst stages, relative mRNA abundance of stress‐related genes HSP 70.1 and HSP 70.2 and pro‐apoptotic genes CASPASE‐3, BID and BAX was higher (p < 0.05) in Groups III and II than that in controls with the exception of stress‐related gene HSF1. Expression level of anti‐apoptotic genes BCL‐XL and MCL‐1 was also higher (p < 0.05) in Groups III and II than that in controls at both 8–16‐cell and blastocyst stages. Among the genes related to embryonic development, at 8–16‐cell stage, the expression level of GDF9 was higher (p < 0.05) in Group III than that in controls, whereas that of GLUT1, ZAR1 and BMP15 was not significantly different among the three groups. At the blastocyst stage, relative mRNA abundance of GLUT1 and GDF9 was higher (p < 0.05) in Group II than that in controls, whereas that of ZAR‐1 and BMP15 was not affected. The results of this study demonstrate that exposure of buffalo oocytes and embryos to elevated temperatures for duration of time that is physiologically relevant severely compromises their developmental competence, increases apoptosis and affects stress‐, apoptosis‐ and development‐related genes.     

A Proposed Role for VEGF Isoforms in Sex-Specific Vasculature Development in the Gonad

Many scientists have expended efforts to determine what regulates development of an indifferent gonad into either a testis or ovary. Expression of Sry and upregulation of Sox9 are factors that initiate formation of the testis-specific pathway to allow for both sex-specific vasculature and seminiferous cord formation. Migration of mesonephric precursors of peritubular myoid cells and endothelial cells into the differentiating testis is a critical step in formation of both of these structures. Furthermore, these events appear to be initiated downstream from Sry expression. Sertoli cell secretion of growth factors acts to attract these mesonephric cells. One hypothesis is that a growth factor specific for these cell linages act in concert to coordinate migration of both peritubular and endothelial cells. A second hypothesis is that several growth factors stimulate migration and differentiation of mesonephric 'stem-like' cells to result in migration and differentiation into several different cell lineages. While the specific mechanism is unclear, several growth factors have been implicated in the initiation of mesonephric cell migration. This review will focus on the proposed mechanisms of a growth factor, Vascular Endothelial Growth Factor, and how different angiogenic and inhibitory isoforms from this single gene may aid in development of testis-specific vascular development.     

Elasticity of single-crystal MgO to 8 gigapascals and 1600 kelvin

The cross pressure (P) and temperature (T) dependence of the elastic moduli (Cij) of single-crystal samples of periclase (MgO) from acoustic wave travel times was measured with ultrasonic interferometry: partial differential2C11/ partial differentialP partial differentialT = (-1.3 +/- 0.4) x 10(-3) per kelvin; partial differential2C110/ partial differentialP partial differentialT = (1. 7 +/- 0.7) x 10(-3) per kelvin; and partial differential2C44/ partial differentialP partial differentialT = (-0.2 +/- 0.3) x 10(-3) per kelvin. The elastic anisotropy of MgO decreases with increasing pressure at ambient temperature, but then increases as temperature is increased at high pressure. An assumption of zero cross pressure and temperature derivatives for the elastic moduli underestimates the elastic anisotropy and overestimates the acoustic velocities of MgO at the extrapolated high-pressure and high-temperature conditions of Earth's mantle.     

Medial collateral ligament desmitis of the distal interphalangeal joint in the hindlimb of a horse: treatment with cast immobilisation

A 12‐year‐old show‐jumping mare was presented for investigation of a chronic hindlimb lameness of 16 weeks duration. Perineural anaesthesia and ultrasonography localised the lesion to the medial collateral ligament of the distal interphalangeal joint of the left hindlimb. Treatment consisted of a heavily padded distal limb cast for 6 weeks, strict box rest and a strictly regulated hand walking program. Serial ultrasonographic examinations were performed throughout the rehabilitation period. Collateral ligament desmitis of the distal interphalangeal joint is a commonly diagnosed condition of the forelimb; however, hindlimb collateral ligament desmitis has been rarely reported. Ultrasonographic examination in this case was an invaluable diagnostic and follow‐up tool. Immobilisation of the foot by means of a heavily padded distal limb cast allowed excellent healing of the ligament and is presented as a novel treatment for collateral ligament desmitis. At the time of writing the mare had returned to her previous level of exercise and was showing no signs of lameness.     

Postmortem lesions in the intercarpal ligaments of the equine midcarpal joint

Objective To determine the frequency of damage to the medial palmar intercarpal ligament (MPICL), and the range of sizes of the dorsomedial intercarpal ligament (DMICL) of the midcarpal joint in horses with no history of carpal joint disease.
Materials and methods
Cadaver limbs were collected from 72 horses with no history of carpal joint disease. One hundred and forty-two midcarpal joints were dissected and the MPICL and DMICL were examined. Measurements were made with a digital micrometer.
Results MPICL tearing was present in 88 of 96 joints from horses 2 years and older. Tears were predominantly of the dorsolateral bundle and complete rupture of the dorsolateral and dorsomedial bundles was not observed. Tearing was not present in foals less than 4 months of age and the severity of tearing increased significantly with age (P < 0.0001). Severity of tearing was significantly greater in racing Standardbreds than racing Thoroughbreds (P < 0.01), but there was no significant difference between racing and non-racing horses. The lateromedial thickness of the DMICL ranged from 0.4 mm to 2.6 mm in horses 2 years and older. Lateromedial thickness increased significantly with age, and was significantly greater in racing Standardbreds than racing Thoroughbreds (P < 0.01). There was no significant difference between racing and nonracing horses.
Conclusions Damage confined to the dorsolateral bundle of the MPICL is a common finding in horses over 1 year of age and is probably of little clinical significance. Complete rupture of both dorsolateral and dorsomedial bundles is uncommon in horses with no history of midcarpal joint disease. Variation in size of the DMICL is observed in horses of all ages, but is most marked in 2-year-old horses.     

Derivation, safety and efficacy of a Marek's disease vaccine developed from an Australian isolate of very virulent Marek's disease virus

Objective To develop a serotype 1 Marek's disease (MD) vaccine from a very virulent MDV (vvMDV) pathotype and demonstrate safety and efficacy against early challenge with very virulent field strains in the presence of maternal antibody.
Study design Strain BH 16 was isolated and attenuated by serial cell culture passage. One of two cloned passages was selected for vaccine development following early laboratory-scale protection trials in commercial birds. Comparative protection trials were carried out on the BH 16 vaccine and on a CVI 988 Rispens vaccine using commercial and SPF chickens. Challenge viruses used were either a low passage strain BH 16 virus, the Woodlands No. 1 strain or MPF 57 strain of MDV. The BH 16 vaccine was back-passaged in SPF chickens six times and virus recovered from the final passage and the original vaccine virus were tested for safety. The immunosuppressive potential of the BH 16 and Rispens vaccines was also assessed in parallel.
Results The BH 16 and Rispens vaccines induced comparable levels of protection when used as monovalent or multi-valent vaccines, although protection achieved with the mono-valent vaccines was lower. No gross tumour formation was evident in any birds receiving the BH 16 vaccine or bird-passaged virus, although microscopic lesions were present in 2/12 birds that received the bird-passaged virus. In tests for immunosuppression, there was no histological evidence of damage to either the bursa of Fabricius or the thymus.
Conclusion The BH 16 vaccine was shown to be safe and at least as protective as the Rispens vaccine against three highly virulent MD challenge viruses.