The effects of a dietary antimicrobial on the biological half-life of chenodeoxycholic acid and plasma bile acid concentration patterns in the young pig.

Carbodox (CX), an antimicrobial agent, was fed at 0 or 58 ppm in a 19.5% crude protein corn-soybean metal diet to young pigs (12 to 15 kg). Radiolabeled chenodeoxycholic acid (CDC) was infused into the hepatic portal vein; after each of the subsequent six meals, blood samples were collected from the anterior vena cava (VC) and the hepatic portal (HP) veins. For the first 5 min after CDC infusion, the level of radioactivity in the CX pigs was significantly lower in the HP plasma and the slopes of the two curves of the plasma activity for the first hours were significantly different. The plasma bile acid concentrations (as measured by radioactivity) were significantly higher in the CX-treated animals following all meals. The biological half-life of CDC was 6.4 d in the controls and 5.7 d in the CX pigs. The increased rate of excretion was significant. These data indicate that bile acid metabolism in the young pig was significantly affected by feeding a subtherapeutic level of the antimicrobial CX.

Radionuclide joint imaging: an ancillary technique in the diagnosis of canine hip dysplasia.

Radionuclide joint imaging has been adapted for use in the diagnosis of canine hip dysplasia. Studies were done on 29 growing Labrador Retriever pups between 3 months and 1.5 years of age and on two adult dogs. Initally, pelvic radiographs and joint images were done on pups 12 to 16 weeks of age and were repeated at 2-week intervals thereafter. 99mTechnetium methylene diphosphonate (99mTcMDP), an osteotrphic agent, was the radiopharmaceutical used for all imaging studies. Inteference due to 99mTcMDP accumulation in the urinary bladder was avoided by static abdominal pressure. In 19 of the 21 dogs identified as abnormal by pelvic radiography, a similar diagnosis based on joint imaging was made for a true positive ratio of 0.90. Eight of ten dogs were identified as normal by means of both procedures, for a true negative ratio of 0.80. The overall accuracy was 0.87. Joint imaging was thus shown to be of similar value as pelvic radiography in the diagnosis of hip dysplasia. Joint images, however, displayed information on bone metabolic activity that could not be determined by pelvic radiography.

Chondrolysis associated with cartilage canals of the epiphyseal cartilage of the distal humerus of growing pigs.

The articular-epiphyseal (A-E) cartilage of the distal humeri of 7 pigs weighing 13.1 to 18.2 kg and of 3 pigs weighing 36.4 to 40.9 kg was studied. Frozen samples of A-E cartilage were stained for the presence of reduced nicotinamide adenine dinucleotide dehydrogenase, lactate dehydrogenase, isocitrate dehydrogenase, and uridine diphosphate galactose-4-epimerase. Additional frozen sections and paraffin-processed sections were stained using the Alcian blue-critical electrolyte concentration method, safranin O-fast green, and hematoxylin and eosin. An area of grossly visible, opaque A-E cartilage of the medial condyle corresponded to regions of chondrolysis of the epiphyseal cartilage. The chondrolytic regions contained chondrocytes that did not stain for enzymes, had reduced staining for proteoglycans in the matrix, and were located at the site where the A-E cartilage increased in thickness. Cartilage canals were associated with the chondrolytic areas. Cartilage canals in both groups of pigs were commonly in various stages of chondrification, some of which were associated with degenerative cartilage. The regions of chondrolysis may indicate sites of biomechanical weakness in the A-E cartilage during the transformation of the epiphyseal cartilage into bone.

Use of radionuclide imaging to identify malignant mammary tumor bone metastases in dogs.

Radionuclide imaging techniques were used to indicate the location and incidence of bone metastases in 30 dogs with malignant mammary tumors. The method was successful in distinguishing mammary tumor metastases in the sternum of one dog.

Incomplete linear tibial fractures in two horses.

Incomplete linear tibial fractures were identified in two horses with the aid of scintigraphy. Both horses were treated successfully by strict stall confinement, and both returned to normal athletic activity. Scintigraphy can be used to facilitate the generally difficult diagnosis of incomplete tibial fractures.

Bile acid metabolism in the pig.

To study bile acid metabolism in the pig, indwelling catheters were surgically placed in the hepatic portal vein and the anterior vena cava of 12-17 kg crossbred pigs. The pigs were fed ad libitum for one hr at 0800 and 1600 hrs daily. Two weeks after the surgery, 50 microCi of 24[14C] chenodeoxycholic acid were infused into the hepatic portal vein. The radioactivity in plasma from the two veins was monitored hourly for six hrs following each of six consecutive meals over a 3-day period. Fecal and urine radioactivity were determined for 14 days. It was found that the peak levels of radioactivity in the plasma of both veins were reached within two hrs post-feeding. The biological half-life of chenodeoxycholic acid was determined to be 6.4 days.

Measurement of diffusion of uncharged molecules in articular cartilage.

The diffusion of glucose (180 M.W.), inulin (5,000 M.W.) and dextran (20,000 M.W.) into mature bovine and equine articular cartilage was studied. Concentration profiles were determined using a one-dimensional experimental configuration and the diffusion coefficient and partition coefficient calculated from a theoretical model. Glucose was found to diffuse the fastest, followed by inulin and dextran. The partition coefficient was similarly ordered. The rate of diffusion was found to decrease with increasing diffusion time, indicating a dependence on solute concentration. No time variation was evident in the partition coefficient. In addition, no difference was found between species or between the location sites within the animal joint.