Megakaryocytes in normal dogs have a variety of nuclear forms. The most common variations are a single large multilobed nucleus or a segmented nucleus consisting of irregular nuclear lobes joined by strands of chromatin. Exaggerated segmentation (hypersegmentation) of the nucleus occurs in a small number of megakaryocytes. Megakaryocytes with multiple separate nuclei are infrequently observed. In a 1-mo toxicology study in young adult beagle dogs with PNU-100592, a new oxazolidinone antibacterial agent, a large increase in the number of megakaryocytes with hypersegmented nuclei and multiple separate nuclei was observed. The group mean platelet count was slightly decreased for most PNU-100592-treated groups. Siderocytes were observed on peripheral blood smears, and ring sideroblasts were present on bone marrow smears. Minimal to mild toxicologic lesions were observed in the large intestine, rectum, kidneys, liver, and testes, primarily in the high-dose group. PNU-100592 may be useful in the study of the regulation of endomitosis during megakaryocytopoiesis in the dog.

Acetamides↗

PubMedDate not supplied

Morphologic and biochemical effects of intratracheally administered oil shale in rats.

Young adult rats were given three weekly intratracheal instillations of 30 mg of raw oil shale or spent oil shale suspended in 1.0 ml sterile physiological saline. Positive control groups received similar instillations of 30 mg or 5 mg of quartz. Animals were sacrificed and tissue samples taken for histopathology and biochemical analyses at 3 weeks, 7 weeks, 4 months, and 8 months following the first instillation. Rats exposed to raw shale, spent shale or quartz had increased lung weights compared with controls. Microscopically, all exposed groups developed granulomatous pneumonia and alveolar lipoproteinosis; pulmonary fibrosis was most severe in the quartz-exposed groups and progressed with time in these groups. Total amounts of pulmonary hydroxyproline, prolyl hydroxylase, total protein, and lipid phosphate were increased in shale or quartz-exposed groups; however, concentration of these substances on a per gram of lung tissue basis was not different from control groups.

Animals↗