RESUMEN

A review of existing legislation covering laboratory animals in Latin America is presented. The region presents a spectrum of economic development, political stability, and cultural diversity. With the exception of a few nations, there is a lack of regulations as well as minimal enforcement of existing laws pertaining to laboratory animals. Brazil, Mexico, and Uruguay stand out as the only nations in this region with specific legislation regulating laboratory animal care and use; the history and current status of regulations in these three nations is reviewed.

RESUMEN

We report problems encountered during preparation of tritium-labeled unconjugated bilirubin ((3)H-UCB) from precursor (3)H-5-aminolevulinic acid ((3)H-ALA) in 2 dogs with external biliary drainage installed into the animals under general anesthesia. Under prolonged sedation, 12.9 or 14.0 mCi of (3)H-ALA was administered intravenously in two divided doses, and bile was collected for 9 hours. In one animal, taurocholate (TC) infusion was needed to maintain bile flow. (3)H-UCB was isolated from the bile and recrystallized with the improved method of Webster et al (Webster CC, Tiribelli C, Ostrow JD. J Lab Clin Med 2001;137:370-3). Based on radioactivity and pigment content, hourly bile collections were pooled to optimize specific activities. Surprisingly, in the first dog, only 2.9% of injected radioactivity was recovered in bile and only 14.1% in urine, and the specific activities of the crystalline (3)H-UCB from the two pools were only 39.5 and 30.0 x 10(3) dpm/microg. High-performance liquid chromatography analysis revealed that only 4% of ALA degraded during 5 minutes in injection solution at pH 6.8. The low incorporation of (3)H-ALA and low specific activity of (3)H-UCB was apparently caused mainly by prior degradation and exchange of labile tritium of the (3)H-ALA and probably by enhanced endogenous ALA synthesis caused by the anesthetic/sedative agents. Revised procedures in the second dog improved the incorporation of (3)H-ALA to 11.9% excreted in bile and the specific activity of the crystalline (3)H-UCB to 122.0 and 50.8 x 10(3) dpm/microg, while urinary excretion of tritium increased to 28.5%. These experiences emphasize possible pitfalls in preparing (3)H-UCB by biosynthetic labeling from (3)H-ALA administered to dogs.

Asunto(s)

RESUMEN

Animal strains with specific genetic mutations can serve as powerful tools to study normal and pathologic cellular and molecular processes. The mammalian species with the largest number of known genetic mutations is the mouse. In spinal cord research, mice have not been used as extensively as other species because of the difficulty in accessing and manipulating their spinal cord. We describe the technique of exposing and manipulating the spinal cord of normal mice and of mice with the severe combined immunodeficiency (scid) mutation. Surgical outcome and complications are discussed. We conclude that dorsal laminectomy with subsequent access and manipulation of the spinal cord and its roots can be accomplished consistently with practice.

Asunto(s)

RESUMEN

The owl monkey (Aotus nancymae) is a primate with a bile acid and biliary lipid profile resembling that of humans. Aotus spp. are among the rare species, including humans, that spontaneously develop cholesterol gallstones. With dietary induction the owl monkey proved a rapid, reliable model of cholesterol cholelithiasis. Six owl monkeys, three of each sex, were fed a diet supplemented with 1.5% cholesterol for 5 weeks. Each week blood samples were drawn for cholesterol determination, and bile samples were obtained by ultrasound-guided percutaneous aspiration of the gallbladder. Weekly ultrasound imaging documented development of gallbladder sludge in all animals, with eventual stone formation in five of six. At necropsy after 5 weeks consuming the diet, all animals had distinct sludging and/or small stones in the gallbladder, correlating with the ultrasound findings. Plasma cholesterol values remained lower in females but increased markedly in some males to > 1,400 mg/dl. Histologic examination revealed mild, diffuse hepatocellular lipidosis and degeneration in four of six animals. Detailed examination of the gallbladder indicated that transhepatic needle punctures induced minimal focal abnormalities, judged inconsequential. In contrast to rodent models commonly in use, owl monkeys have liver and digestive tract anatomy and bile physiology that is similar to that in humans. These similarities give this model the potential to substantively improve understanding of the pathogenesis, treatment, and prevention of human cholesterol gallstones. This model can provide sequential, simultaneous correlation of plasma and biliary lipids, imaging of gallbladder contents, and physiologic processes.

Asunto(s)

RESUMEN

Bile samples were obtained from adult owl monkeys by ultrasound-guided percutaneous cholecystocentesis, using a transhepatic approach. Sampling frequency was once weekly over a 5-week period. Clinical recovery from each procedure was rapid. Animal body weights fluctuated within 22% of baseline over the study period, but maximal weight loss in any animal was less than 3% at the study's end. At necropsy, gross lesions in the liver and gallbladder were minimal. Histologic examination revealed mild focal cholecystitis in the gallbladder of four of six animals, focal pericholecystitis in three of six animals, and foci of gallbladder fibrosis in two animals. Changes were consistent with repeated trauma from the centesis procedure. Gallbladder mucosa was judged normal in all animals. Body weight fluctuations were attributed to a change in diet, part of a concurrent study, rather than to the centesis procedure. Ultrasound-guided cholecystocentesis provides a rapid, minimally traumatic, and safe method for repeated bile sampling in a small nonhuman primate.

Asunto(s)

RESUMEN

Red blood cell populations separated by density centrifugation were compared in a dynamic assay of osmotic stress. Red blood cells from Beagles genotypically normal and nonanemic (nonaffected), Beagles with inherited hemolytic anemia (anemic), and Beagles presumed to be carriers of the anemia trait (trait carriers) were examined for rate and extent of swelling after exposure to the ionophore A23187 in a medium containing calcium and potassium chloride. Comparisons were made between RBC populations separated on the basis of density. Significant differences were observed in the rates of cell swelling in RBC populations separated by density between nonaffected and anemic Beagles. The response of RBC from Beagles presumed to carry the anemia trait was similar to that of RBC from nonaffected dogs. One phenotypic expression of this inherited abnormality of RBC in Beagles was an accelerated rate of RBC swelling under osmotic stress, and this swelling response diminished with increasing RBC density.

Asunto(s)