Bone grafting

Bone grafts in clinical practice are primarily used to help achieve bony union in cases of indolent healing of fractures or pseudoarthrosis; to supplement the healing of certain fresh fractures; to promote fusion (arthrodesis) of joints damaged by injury, disease, or deformity, and to fill defects in bone created by tumors, chronic infection, or injury. This article considers the types and functions of bone grafts.     

Risk factors for lower respiratory tract disease in a cohort of feedlot cattle

Using data collected from company lot records, potential risk factors related to feedlot management, the cattle, and climate were determined. The risk factors were analyzed by use of weighted multiple regression techniques to determine their effects on the incidence of lower respiratory tract disease in a cohort of 95 lots containing 17,696 cattle. The gender of the cattle, the number of days that groups of cattle filled a lot, pregnancy checking of heifers, and the average temperature change in the first 14 days in which the cattle were on feed significantly influenced the incidence of lower respiratory disease. The incidence of lower respiratory tract disease was most influenced by risk factors in the first 30 days on feed.     

Hemodynamic effects of xylazine in the calf

The hemodynamic effects of sedative level doses of xylazine in five chronically instrumented calves were studied. These effects included immediate and prolonged reductions in heart rate, cardiac output, arterial blood pressure, and left ventricular dp/dt max. Stroke volume showed an initial decrease in value with a return in 15 minutes to base-line values. Total peripheral resistance, end-diastolic left ventricular pressure, end-diastolic left ventricular volume, and left ventricular residual fraction were increased after drug administration. The results indicate that a depressed myocardium results from xylazine administration. With one exception (the absence of a hypertensive response), these effects largely parallel, both quantitatively and qualitatively, those seen with this drug in other species. Sedation by xylazine is produced in cattle at doses which are small compared to those which is required for sedation in other species. These same small doses in cattle also cause hemodynamic changes.     

Promotion of floral initiation in ‘Fuerte’ avocado by low temperature and short daylength

Potted avocado (Persea americana Mill., cv. ‘Fuerte’) plants were maintained in growth cabinets for up to 32 weeks and new growth observed for flower formation. Flowers were formed if temperatures were 20°C or below, but with 25° or 30°, even if only for 1 hour per day, flower formation was inhibited. Time to flowering was accelerated, but number of flowers reduced, if daylength was shortened from 15 h to 9 h. With low temperature and short days, full bloom was about 4 months after starting experiments. Spring flowering of cv. ‘Fuerte’ in the field could follow flower induction about 4 months previously with the onset of winter temperatures and daylengths.