Fine Structural Aspects of Postnatal Development of Feline Lung

Lung development was studied in late prenatal, 1-, 7-, 14-, and 21-days postnatal and adult cats. Cats were born with a few alveoli, and the lungs appeared to have patches of primitive air spaces (saccules). The saccules of prenatal kittens were thick walled, very cellular, and lined by type II pneumocytes. Eosinophils were observed in the septum, intraepithelially, and in the alveolar space of growing cats. Secondary septa were flanked by a double capillary network and divided saccules into multiple shallow alveoli. Septation was irregular and time dependent and not completed by day 231 of postnatal life. Elastic fibers accumulated at the tip of the septa, seemingly playing an important role in alveolar formation. Type II pneumocytes were located at the base of the secondary septa in growing cats, thus strengthening secondary septa to withstand the stresses of respiration. Pores of Kohn were not observed in growing cats.     

Effects of a specific thromboxane synthetase inhibitor on thromboxane generation and excretion in healthy dogs

A specific thromboxane synthetase inhibitor, 3-methyl-2 (3-pyridyl)-1-indoleoctanoic acid (CGS 12970) was administered orally to 6 healthy adult Beagles at a dosage of 30 mg/kg of body weight. Blood generation of thromboxane B2 and urinary excretion of thromboxane B2 were measured before and after administration of CGS 12970. Although 97 +/- 0.4% inhibition of thromboxane B2 generation was observed within 2 hours after a single dose of CGS 12970 was administered orally, an effect on urinary excretion of thromboxane B2 was not observed. Additionally, oral administration of 30 mg/kg every 12 hours resulted in 80 +/- 14% inhibition of thromboxane B2 generation but had no effect on urinary thromboxane B2 excretion.     

Fragments of the HIV-1 Tat protein specifically bind TAR RNA

Proteolytically produced carboxyl-terminal fragments of the human immunodeficiency virus type-1 (HIV-1) Tat protein that include a conserved region rich in arginine and lysine bind specifically to transactivation response RNA sequences (TAR). A chemically synthesized 14-residue peptide spanning the basic subdomain also recognizes TAR, identifying this subdomain as central for RNA interaction. TAR RNA forms a stable hairpin that includes a six-residue loop, a trinucleotide pyrimidine bulge, and extensive duplex structure. Competition and interference experiments show that the Tat-derived fragments bind to double-stranded RNA and interact specifically at the pyrimidine bulge and adjacent duplex of TAR.