RESUMEN
YAC clones were modified via homologous recombination by transfecting yeast cells containing YAC with plasmid PRAN4 DNAs. The integration of neo gene into YAC DNA was identified using Southern blotting and PCR methods. A modified YAC that carried 330 kb human DNA was introduced into L929 cells through PEG mediated spheroplast fusion, and G418 resistant colonies were obtained.
RESUMEN
Studies were undertaken to evaluate the effect of Botulinum neurotoxin type-A (BoNTA) preparation on oxytocin-induced contractions of pregnant human myometrium in vitro. Human myometrial tissue was exposed to increasing concentrations (1-50 000 U/mL) of BoNT/A. Isometric contractions were measured using a force displacement transducer. The cumulative effect of BoNT/A on myometrial activity (time to half relaxation [TTR50], frequency, and amplitude) was evaluated. The frequency of myometrial contractions was depressed by 40% from baseline (P < .05) and relaxation time was increased by 30% (P < .05) from baseline within a narrow range of concentrations. There was no significant difference in amplitude. The observed effects were rapidly reversed after complete wash out of the tissue. BoNT/A or its analogues with more specific tissue affinity may be of value as future agents for prevention of unwanted uterine contractile activity associated with preterm labor and fetal surgery.