Relative bioavailability of danazol in dogs from liquid-filled hard gelatin capsules.

Danazol was dissolved in non-aqueous mixtures containing either polyethylene glycol 400 or polysorbate 80, and filled into hard gelatin capsules at 50 mg concentrations. The bioavailability of these formulations was compared with commercial danazol capsules in a two-way crossover study using young female beagle dogs. Both formulations showed greater oral bioavailability when compared with either the 100 or 200 mg commercial brand of danazol. The bioavailability of the polyethylene glycol 400 and polysorbate 80 formulations was enhanced 3.7 and 15.8 times, respectively, when compared at the 100 mg dose level.

Adenovirus E1A specifically blocks SWI/SNF-dependent transcriptional activation.

Expression of the adenovirus E1A243 oncoprotein in Saccharomyces cerevisiae produces a slow-growth phenotype with accumulation of cells in the G1 phase of the cell cycle. This effect is due to the N-terminal and CR1 domains of E1A243, which in rodent cells are involved in triggering cellular transformation and also in binding to the cellular transcriptional coactivator p300. A genetic screen was undertaken to identify genes required for the function of E1A243 in S. cerevisiae. This screen identified SNF12, a gene encoding the 73-kDa subunit of the SWI/SNF transcriptional regulatory complex. Mutation of genes encoding known members of the SWI/SNF complex also led to loss of E1A function, suggesting that the SWI/SNF complex is a target of E1A243. Moreover, expression of E1A in wild-type cells specifically blocked transcriptional activation of the INO1 and SUC2 genes, whose activation pathways are distinct but have a common requirement for the SWI/SNF complex. These data demonstrate a specific functional interaction between E1A and the SWI/SNF complex and suggest that a similar interaction takes place in rodent and human cells.

Essential role of Swp73p in the function of yeast Swi/Snf complex.

Swi/Snf protein was purified previously from the yeast Saccharomyces cerevisiae as an 11-polypeptide complex, including five novel Swp polypeptides. Here we present evidence concerning the role of Swp73p in the function of the complex. Deletion mutants in the SWP73 gene display phenotypes similar to those of swi and snf mutants, and in addition are temperature-sensitive. Swp73p is required for transcriptional activation by full-length glucocorticoid receptor (GR), but not by all GR derivatives. Swp73p is also required for activation with an enhancer element that binds the transcription factors Swi5p and Pho2p, which may underlie the defects in HO expression observed with swi and snf mutants. A single amino acid change in the protein confers phenotypes that are similar to those observed in the swp73 delta strain, but in some cases the two strains behave differently. The extent to which Swp73p is required for assisting transcriptional activation depends on the activator and promoter tested. Homologs of SWP73 are present in S. cerevisiae, Ashbya gossypii, Caenorhabditis elegans, and mice, indicating that SWP73 may belong to a family of related genes encoding proteins with analogous functions.

Complete sequence of the genomic RNA of O'nyong-nyong virus and its use in the construction of alphavirus phylogenetic trees.

The alphaviruses are a group of about 25 positive-strand RNA viruses that are important human and veterinary pathogens and that are geographically dispersed. We report here the complete nucleotide sequence of the genomic RNA of the alphavirus, O'nyong-nyong virus. The RNA is 11,835 nucleotides in length and the organization of the genome is typical of alphaviruses. Phylogenetic trees were constructed from the protein sequences of O'nyong-nyong and six other alphaviruses. Trees were constructed for each nonstructural and structural viral protein individually in order to detect any possible recombination events, as well as to examine the differential divergence among the various proteins. The members of each tree can be divided into three subgroups: the Semliki Forest virus subgroup (Semliki Forest, O'nyong-nyong, and Ross River viruses), the eastern equine encephalitis virus subgroup (eastern equine encephalitis and Venezuelan equine encephalitis viruses), and the Sindbis virus subgroup. Sindbis virus, which is geographically restricted to the Old World, is more closely related to the eastern equine encephalitis subgroup, which are New World viruses, than it is to the Semliki Forest virus subgroup, which are mostly Old World viruses. Western equine encephalitis virus is a special case because it is a recombinant virus. Its nonstructural and capsid proteins are most closely related to those of eastern equine encephalitis virus while its glycoproteins are most closely related to those of Sindbis virus. All members of a given subgroup have diverged the same amount from their common node point. However, the structural proteins of the Semliki Forest virus subgroup are more closely related to one another than those of the eastern equine encephalitis virus subgroup. This difference probably indicates that the members of the eastern equine encephalitis virus subgroup diverged earlier than the members of the Semliki Forest virus subgroup, which suggests that the alphaviruses originated in the New World.

Effect of surfactant on tetracycline absorption across everted rat intestine.

Absorption of tetracycline hydrochloride (500 micrograms/ml) from oxygenated modified Krebs buffer in randomized everted rat jejunal segments was determined alone and in the presence of calcium, polysorbate 80, and calcium plus polysorbate 80. Surfactant increased absorption of tetracycline in the presence and absence of calcium, with 0.01% (w/v) polysorbate 80 increasing transfer to the greatest extent of the concentrations examined(0.005, 0.01, 0.05, 0.1, and 1%); tetracycline hydrochloride + 12.5 mM CaCl2, 143 +/- 45 micrograms/ml; tetracycline hydrochloride + polysorbate 80, 389 +/- 18 micrograms/ml; tetracycline hydrochloride + 12.5 mM CaCl2 + polysorbate 80, 255 +/- 31 micrograms/ml. On the premise that the effective surfactant concentration is similar to the critical micelle concentration, an absorption mechanism based on micellar solubilization is postulated.

Oxygen solubilization in egg lecithin dispersed in distilled water and physiological electrolyte fluids.

Gaseous oxygen solubilization in egg lecithin dispersed in distilled water, saline, and a multi-ion physiological electrolyte solution was determined and compared to controls deficient in egg lecithin. Significant oxygen solubilization occurred in the presence of egg lecithin. Oxygen solubilization was significantly greater in saline and in the multi-ion physiological electrolyte solution than in distilled water.

Sodium acetate as a preservative in protein hydrolysate solutions.

The inhibitory effect of sodium acetate on microorganism growth in protein hydrolysate solutions was studied. Solutions of 5% protein hydrolysate and 5% dextrose in water (seven parts) and 50% dextose in water (three parts) containing 0, 30, 50 and 90 mEq/liter of sodium acetate were inoculated with Staphylococcus aureus, Escherichia coli, Candida albicans and Pseudomonas aeruginosa. The number of colony-forming units in the solutions after inoculation was compared with that after incubation for 24 hours at 37 C. Sodium acetate inhibited growth of S aureus and E coli. Growth of P aeruginosa was inhibited in protein hydrolysate solutions with and without sodium acetate; inhibition could not be attributed solely to sodium acetate and may have been releated to pH of the solutions (4.7 to 5.4). Growth of C albicans was not inhibited by sodium acetate. Sodium acetate reduced growth of some common contaminants of protein hydrolysates. Sodium acetate is known to reduce metabolic acidosis, a reported complication of parenteral nutrient therapy and a possible predisposing factor in C albicans sepsis. Addition of sodium acetate to protein hydrolysate solutions should be considered seriously.

Dissolution rates of hydrocortisone and prednisone utilizing sugar solid dispersion systems in tablet form.

The utilization of ternary sugar solid dispersion systems and the incorporation of these systems into tablet dosage forms were investigated. The dispersion systems were prepared by the fusion method using 50% sucrose-50% mannitol and 50% sorbitol-50% mannitol. Other systems investigated utilized sorbitol, mannitol, and polyethylene glycol 6000 for comparison. The drug component was hydrocortisone or prednisone. The results from a modified NF XIII dissolution rate determination revealed that the mannitol system had the fastest dissolution rate, followed by sorbitol-mannitol, sucrose-mannitol, sorbitol, and finally, polyethylene gylcol 6000. The corticosteroids were stable and did not decompose during preparation of the dispersion systems or direct compression of the tablets. A short-term stability study revealed that the tablets retained their fast dissolution rates and that the tablet characteristic tests, i.e., tablet hardness, remained unchanged. The use of sugar combinations overcame some difficulties previously reported with single sugar systems.

Airway function in sarcoidosis.

Airway function was studied in 18 patients with sarcoidosis, aged 18 to 49 years. Eleven of the patients were smokers. All patients had the characteristic functional changes of restrictive lung disease: decreased lung volumes and single breath diffusing capacity, and increased static transpulmonary pressures. Abnormal airway function was demonstrated in every patient by at least one test, and nearly always by multiple tests. Specific airway conductance was abnormally low in two patients. The ratio of the 1 second forced expiratory volume to the forced vital capacity was decreased in six patients. Frequency dependence of dynamic compliance was demonstrated in eight patients. The ratio of closing volume to vital capacity was increased above age-corrected predictions in all but two patients. Upstream airway resistance was abnormally increased in 16 of the patients. These results suggest that airway dysfunction is not uncommon in sarcoidosis.

Electromyographic response of respiratory muscles during elastic loading.

The response of respiratory motor neurons to graded elastic loading was assessed in anesthetized dogs by recording the electromyogram (EMG) from the diaphragm (ED) and the intercostal muscle (EIC). Elastic loads were applied for 1-20 breaths. The effects of changes in PCO2 on respiratory motor neuron output was assessed by applying loads during the course of CO2 rebreathing. On the first loaded breath, ED and EIC increased reflexly due chiefly to prolongation of inspiration. Vagotomy or vagal cooling to block the Hering-Breuer reflex eliminated the increase in ED and diminished the increase in EIC. During the second to fifth breath, the level of EMG activity was disproportionately high for the level of PCO2, suggesting an additional reflex component over and above the reflex activity present on the first loaded breath.

Effects of hypercapnia on mouth pressure during airway occlusion in conscious man.

The effects of hypercapnia and inspiratory flow-resistive loading on mouth pressure during periods of arrested airflow were studied in conscious human subjects to determine the usefulness of inspiratory muscle force in the assessment of respiratory neural efferent activity. Hypercapnia increased the peak end-inspiratory mouth pressure (Ppeak) during complete airway occlusion and the pressures at 100, 200, and 300 ms after the onset of inspiration (P100, P200, P300). During rebreathing without added mechanical loads, P100 and Ppeak increased linearly with the electrical activity of the diaphragm and changes in P100 and Ppeak during hypercapnia correlated well with ventilatory responses to PCO2 (DELTA V/DELTA PCO2) suggesting that occluded mouth pressures are reliable measures of respiratory activity. In individuals with the greatest reduction in delta V/DELTA PCO2 during inspiratory flow-resistive loading, changes in P100 and Ppeak with PCO2 increased only minimally. In contrast, there was a much greater increase in occluded mouth pressures with hypercapnia in the presence of mechanical loading when inspiratory flow-resistive loading failed to depress delta V/DELTA PCO2. In all subjects, occluded mouth pressures were greater at any given PCO2 during mechanical loading than during free breathing. Mechanical loading resulted in augmented respiratory neural efferent activity unexplained by alterations in chemical stimulation.

Effect of hypoxia on the pressure developed by inspiratory muscles during airway occlusion.

The effect of progressive isocapnic hypoxia on the pressure generated by the inspiratory muscle during airway occlusion was studied in 10 awake subjects during normal and obstructed breathing. Isocapnic hypoxia was produced by rebreathing a gas mixture of 6% CO2 in air while the expired gas was passed through a CO2 scrubber so as to maintain PACO2 constant (42.6 mmHg +/- 2.2 SE). Occlusion of the airway was performed randomly for a single breath at FRC. In all 10 subjects maximal pressure (Ppeak) and the pressures measured 100, 200, 300, and 400 ms after the onset of inspiration increased during hypoxia. Furthermore, good correlation was noted between the occlusion pressure response to hypoxia (delta P/DELTA[1/PO2-32]) and simultaneous changes in ventilatory response to hypoxia (delta VI/DELTA[1/PO2-32]). The occlusion pressure response to hypoxia therefore seems to be a reliable measure of respiratory center output. When rebreathing was repeated during inspiratory resistive loading, the occlusion pressure at any given PO2 and delta P/DELTA(1PO2-32) measured in the first 400 ms of inspiration increased in 9 of 10 subjects. Since PACO2 and PAO2 during both control and loaded experiments were the same, the increase in occlusion pressure in the presence of flow-resistive loading appeared to represent a neurally mediated increase in inspiratory motoneuron activity.

Oxygen solubilization by lung surfactant.

To illustrate the concept of solubilization as a possible mode of gas transport in biological systems, dog lung surfactants in varying concentrations were tested for their ability to solubilize oxygen. The degree of gas solubilization was determined by GC, using a modified tonometer as an absorption chamber. The concentration of surfactant was found to be an essential factor for gas solubilization. Surfactant concentration above the CMC yielded anomalously high gas absorption. Solubilization of the gas is thought to occur by a partitioning effect into the interior of surfactant micelles.