RESUMO
We studied the mechanisms responsible for instability of hybrid derivatives of staphylococcal R plasmids in B. subtilis cells. Four pBCH plasmids were constructed from staphylococcal chloramphenicol-resistance plasmid pC756 ligated with pBR322 or pUC8 vectors, and two pAEC plasmids contained pC756 plasmid, erm gene from S. aureus pE3692 and pBR322 plasmid vector. The level of instability of these recombinant plasmids was clearly related to their sizes, the larger derivatives were segregationally highly unstable. The four hybrid pBE plasmids constructed from erythromycin-resistant pE3692 plasmid or its deletion derivative and pBR322 vector were poorly maintained in B. subtilis rec+ strain in comparison with the B. subtilis (recE4) strain. Moreover, the absence in pBE-hybrids of a part of palA sequence led to considerable reduction of plasmid stability in B. subtilis cells. However, the clones of B. subtilis harbouring pBE plasmids integrated into the bacterial chromosome presented much higher stability of the plasmid erm gene than the clones maintaining autonomously replicating plasmids.
Assuntos
Bacillus subtilis/genética , Fatores R , Escherichia coli/genética , Vetores Genéticos , Staphylococcus/genética , Transformação GenéticaRESUMO
UNLABELLED: The authors discuss the indications for the operation, the surgical technique and results obtained in 92 patients who have been operated for ptosis (109 operations) by the modified method of Berke and Neuhaus. From the experience of the authors it appears that the best approach is a subciliary one especially in congenital ptosis. The Neuhaus method showed to be successful in patients with ptosis connected with the "jaw-winking" Marcus-Gunn phenomenon; in these patients one obtained the elevation of the upper lid and liquidation of the synkinesis. RESULTS: in congenital unilateral ptosis very good result was achieved in 63 p.c., a good one in 32.3 p.c., a poor one in 4.8 p.c. In bilateral ptosis very good result could be achieved in 36.8 p.c., a good one in 52.5 p.c. and a poor one in 10.6 p.c. of cases. Insufficiency of the lid closure as a principal complication of operation was seen in 6 patients (6.5 p.c.) without any consecutive pathological changes in the eye.
