Down-regulation of ornithine decarboxylase by an increased degradation of the enzyme during gastrulation of Xenopus laevis.

The present study was designed to analyze the regulation of the levels of the polyamines and their biosynthetic enzymes during embryonic development of Xenopus laevis. The activity of ornithine decarboxylase (ODC), a rate-controlling enzyme in polyamine biosynthesis, is elevated until, during gastrulation, there is a precipitous drop in activity. This is not attributable to a decrease in ODC mRNA content and polysome profiles reveal no apparent decrease in ODC message associated with polysomes.

Exophthalmos associated with frontal sinus osteomyelitis in a puppy.

A three-month-old, male Great Dane puppy developed progressive left exophthalmos, epiphora, and swelling of the left frontal bone. Radiographs revealed obliteration of the left frontal sinus by a bone-like density, and lateral sinus wall thickening with extension into the left orbit. On surgical exploration and trephination, the left frontal sinus was filled with soft bone which contained multiple pockets of mucopurulent material.

Ocular and orbital porcupine quills in the dog: a review and case series.

A retrospective evaluation of 5 cases of orbital or intraocular porcupine quills in the dog and a literature review from MEDLINE (1983-1995) is presented. This paper reviews the diagnosis, therapy, and visual prognosis of ocular and orbital quills in the dog. Distinguishing penetration and perforation of the eye and intraocular structures is paramount in establishing a visual prognosis and appropriate therapy.

Thymoma in a geriatric rabbit with hypercalcemia and periodic exophthalmos.

An 8-year-old rabbit was referred to an ophthalmologist because of intermittent bilateral exophthalmos and prolapse of the nictitating membranes. Both eyes could be retropulsed normally, and the exophthalmos was induced with ventroflexion. The rabbit had moderate hypercalcemia and a large mediastinal mass that could be seen on thoracic radiographs.

Epiphora associated with dacryops in a dog.

A six-month-old basset hound was presented with unilateral right epiphora and medial canthal and maxillary bone swelling. Skull radiographs and dacryocystorhinography revealed a nasal cyst, right nasolacrimal duct dilatation, and obstruction. Laboratory examination of the cyst confirmed the diagnosis of dacryops, a cyst of lacrimal gland origin.

Inhibition of SKF 89976-A of the gamma-aminobutyric acid release from primary neuronal chick cultures.

Neuronal cultures were made from the 8-d-old embryonic chick telencephalon. The primary culture model was further improved, the medium composition was modified, and the cells grown for 10 d, which allowed the development of relatively differentiated neurones. A superfusion protocol was developed and applied to study the release of [3H]-gamma-aminobutyric acid ([3H]GABA).

Magnetic resonance imaging of the canine and feline eye, orbit, and optic nerves and its clinical application.

The purpose of this study was to investigate magnetic resonance imaging of the normal canine and feline eye, orbit and optic nerves using proton density-weighted, T(1)-weighted and T(2)-weighted images. The clinical application of magnetic resonance imaging in veterinary ophthalmology was also investigated using three clinical cases: a feline orbital melanoma, a feline optic nerve meningioma, and a canine orbital fibrosarcoma. Gadolinium diethylenetriamine pentaacetic acid enhanced magnetic resonance imaging was completed on the case of feline optic nerve meningioma.