Gene transfer methods for transplantation.
Explore the source record for details and available documents.
Gene Transfer Techniques↗
Biomedical subjects
T Ku
Publications and source records attributed to T Ku.
Lavage administration of dilute recombinant surfactant in acute lung injury in piglets.
In an acute lung injury model, we previously observed reversal of pulmonary dysfunction with natural surfactant administered by lavage (dose = 18 mg/kg phospholipid). The present study questioned whether a lower dose of phospholipid would be effective if a recombinant preparation rather than natural surfactant were used. Acute lung injury was induced by repeated saline lung lavage in ventilated, sedated, and paralyzed piglets. Three concentrations of recombinant surfactant were studied (low phospholipid, 1 mg/mL; medium phospholipid, 4 mg/mL; high phospholipid, 13.5 mg/mL). Control piglets received no surfactant. Thirty-five milliliters per kilogram of surfactant was administered by gravity, followed by passive drainage of excess fluid. All treatment groups retained similar volumes (4.7+/-0.3 mL/ kg), corresponding to phospholipid doses of 4+/-0.4, 22+/-3, and 67+/-4 mg/kg in low, medium, and high-dose groups, respectively. Treatment groups showed significant improvement in Pao2 compared with controls. Other parameters different from controls were found in only the medium and high-dose groups. All surfactant-treated groups showed improvement over time in Pao2, Paco2, lung resistance mean airway pressure, functional residual capacity, and dynamic compliance. These data support the statement that whereas there is a dose response to exogenous surfactant, the effective dose of recombinant surfactant in acute lung injury may be as low as 4 mg/kg phospholipid when administered by lavage.
Animals↗
Mutations in ribosomal protein L10e confer resistance to the fungal-specific eukaryotic elongation factor 2 inhibitor sordarin.
The natural product sordarin, a tetracyclic diterpene glycoside, selectively inhibits fungal protein synthesis by impairing the function of eukaryotic elongation factor 2 (eEF2). Sordarin and its derivatives bind to the eEF2-ribosome-nucleotide complex in sensitive fungi, stabilizing the post-translocational GDP form. We have previously described a class of Saccharomyces cerevisiae mutants that exhibit resistance to varying levels of sordarin and have identified amino acid substitutions in yeast eEF2 that confer sordarin resistance. We now report on a second class of sordarin-resistant mutants. Biochemical and molecular genetic analysis of these mutants demonstrates that sordarin resistance is dependent on the essential large ribosomal subunit protein L10e in S. cerevisiae. Five unique L10e alleles were characterized and sequenced, and several nucleotide changes that differ from the wild-type sequence were identified. Changes that result in the resistance phenotype map to 4 amino acid substitutions and 1 amino acid deletion clustered in a conserved 10-amino acid region of L10e. Like the previously identified eEF2 mutations, the mutant ribosomes show reduced sordarin-conferred stabilization of the eEF2-nucleotide-ribosome complex. To our knowledge, this report provides the first description of ribosomal protein mutations affecting translocation. These results and our previous observations with eEF2 suggest a functional linkage between L10e and eEF2.
Amino Acid Sequence↗
Elongation factor 2 as a novel target for selective inhibition of fungal protein synthesis.
Elongation factor 2 (EF2) is an essential protein catalyzing ribosomal translocation during protein synthesis and is highly conserved in all eukaryotes. It is largely interchangeable in translation systems reconstituted from such divergent organisms as human, wheat, and fungi. We have identified the sordarins as selective inhibitors of fungal protein synthesis acting via a specific interaction with EF2 despite the high degree of amino acid sequence homology exhibited by EF2s from various eukaryotes. In vitro reconstitution assays using purified components from human, yeast, and plant cells demonstrate that sordarin sensitivity is dependent on fungal EF2. Genetic analysis of sordarin-resistant mutants of Saccharomyces cerevisiae shows that resistance to the inhibitor is linked to the genes EFT1 and EFT2 that encode EF2. Sordarin blocks ribosomal translocation by stabilizing the fungal EF2-ribosome complex in a manner similar to that of fusidic acid. The fungal specificity of the sordarins, along with a detailed understanding of its mechanism of action, make EF2 an attractive antifungal target. These findings are of particular significance due to the need for new antifungal agents.
Antifungal Agents↗
Promoting meconium clearance from the lungs of the neonatal piglet with asymmetric high frequency oscillation.
To investigate the role of high frequency oscillation (HFO) in promoting meconium clearance from the airway, we used a commercially available ventilator configured with maximal expiratory flow exceeding inspiratory flow (asymmetric HFO or AHFO). We hypothesized that AHFO would move meconium in an expiratory direction (toward the ventilator). We first tested our hypothesis in vitro and, later, in vivo using the neonatal piglet. In vitro experiments using a Plexiglas airway confirmed meconium movement in an expiratory direction when bias ratio was > or = 2. For in vivo experiments, each piglet received a 3 mL/kg intratracheal bolus of a 44 g/100 mL meconium mixture followed by 45 min of mechanical ventilation. Then, in part 1, the piglet was placed in a 15 degree head down tilt position and randomized to either AHFO [ratio of inspiratory time/expiratory time (I:E) of 70:30] or HFO (I:E ratio of 30:70). After 30 min of either AHFO or HFO, the piglet was crossed over to the alternate strategy for an additional 30 min. For part 2, we maintained the piglet on either AHFO or HFO continuously for 4 h. Results demonstrate that, although there was a tendency for larger volumes of meconium to be aspirated from the airway during AHFO in part 1 experiments, there was no difference found in part 2. We also found no significant differences in blood gases or hemodynamic measurements between AHFO and HFO during the prolonged observation period in part 2 of our study. We conclude that AHFO is of no benefit in the treatment of meconium aspiration syndrome.
Animals↗
Chemical approaches to improve the oral bioavailability of peptidergic molecules.
This review discusses both tools and strategies that may be employed as approaches towards the pursuit of orally active compounds from peptidergic molecules. Besides providing a review of these subjects, this paper provides an example of how these were utilized in a research programme at SmithKline Beecham involving the development of orally active GPIIb/IIIa antagonists. The tools for studying oral drug absorption in-vitro include variants of the Ussing chamber which utilize either intestinal tissues or cultured epithelial cells that permit the measurement of intestinal permeability. Example absorption studies that are described are mannitol, cephalexin, the growth hormone-releasing peptide SK&F 110679 and two GPIIb/IIIa antagonist peptides SK&F 106760 and SK&F 107260. With the exception of cephalexin, these compounds cross the intestine by passive paracellular diffusion. Cephalexin, on the other hand, crosses the intestine via the oligopeptide transporter. Structure-transport studies are reviewed for this transporter. The tools for studying oral drug absorption in-vivo involve animals bearing in-dwelling intestinal or portal vein catheters. A study of the segmental absorption of SK&F 106760 is provided. The review concludes with two chemical strategies that may be taken towards the enhancement of oral bioavailability of peptidergic molecules. The first strategy involves the chemical modification of peptides which enhance intestinal permeability, specifically the modification of amide bonds. The second strategy involves the design of compounds bearing nonpeptide templates, which are more amenable to the discovery of compounds with oral activity, from peptide pharmacophore models. An example is given regarding the discovery of SB 208651, a potent orally active GPIIb/IIIa antagonist, designed from the peptides SK&F 106760 and SK&F 107260.
Absorption↗
Alpha 1-adrenoceptors: pharmacological classification and newer therapeutic applications.
Explore the source record for details and available documents.
Adrenergic alpha-1 Receptor Antagonists↗
Myocardial positron tomography with manganese-52m.
The biodistribution of radiomanganese (54Mn) was studied in mice, rats, and dogs. Disappearance of radioactivity from the blood was extremely rapid, with a half-time of approximately 0.8 minutes. This resulted in very favorable myocardium-to-blood ratios, even at early times after administration. The myocardial uptake in dogs was greater than 3% at three and 15 minutes, with myocardium-to-blood ratios of about 40:1 at 15 minutes. Positron tomograms obtained with 52mMn clearly demonstrated regional myocardial perfusion. There was good correlation (r = 0.89) of microsphere-to-radiomanganese distribution in the infarcted dog heart.
Animals↗