Intrinsic bent DNA sites in the chromosomal replication origin of Xylella fastidiosa 9a5c

The features of the nucleotide sequences in both replication and promoter regions have been investigated in many organisms. Intrinsically bent DNA sites associated with transcription have been described in several prokaryotic organisms. The aim of the present study was to investigate intrinsic bent DNA sites in the segment that holds the chromosomal replication origin, oriC, of Xylella fastidiosa 9a5c. Electrophoretic behavior analyses, as well as in silico analyses of both the 2-D projection and helical parameters, were performed. The chromosomal segment analyzed contains the initial sequence of the rpmH gene, an intergenic region, the dnaA gene, the oriC sequence, and the 5' partial sequence of the dnaN gene. The analysis revealed fragments with reduced electrophoretic mobility, which indicates the presence of curved DNA segments. The analysis of the helical parameter ENDS ratio revealed three bent DNA sites (b1, b2, and b3) located in the rpmH-dnaA intergenic region, the dnaA gene, and the oriC 5' end, respectively. The chromosomal segment of X. fastidiosa analyzed here is rich in phased AT tracts and in CAnT motifs. The 2-D projection indicated a segment whose structure was determined by the cumulative effect of all bent DNA sites. Further, the in silico analysis of the three different bacterial oriC sequences indicated similar negative roll and twist >34.00° values. The DnaA box sequences, and other motifs in them, may be associated with the intrinsic DNA curvature.

Intrinsically bent DNA in replication origins and gene promoters

Intrinsically bent DNA is an alternative conformation of the DNA molecule caused by the presence of dA/dT tracts, 2 to 6 bp long, in a helical turn phase DNA or with multiple intervals of 10 to 11 bp. Other than flexibility, intrinsic bending sites induce DNA curvature in particular chromosome regions such as replication origins and promoters. Intrinsically bent DNA sites are important in initiating DNA replication, and are sometimes found near to regions associated with the nuclear matrix. Many methods have been developed to localize bent sites, for example, circular permutation, computational analysis, and atomic force microscopy. This review discusses intrinsically bent DNA sites associated with replication origins and gene promoter regions in prokaryote and eukaryote cells. We also describe methods for identifying bent DNA sites for circular permutation and computational analysis.

La toxina botulínica es efectiva en el tratamiento a corto plazo de acalasia esofagica. Resultados preliminares de un estudio randomizado / The botulinum toxin is effective in the short-term treatment of esophageal achalasia. Preliminary results of a randomized trial

Botulinum toxin (BoTox) is a potent inhibitor of the release of acetylcholine from terminal nerves and has been used succesfully in spastic disorders of skeletal muscle. Its used for the treatment of disorders of gastrointestinal smooth muscle has recently been explored. In this study we evaluated the efficacy of transendoscopic injection of BoTox in 13 symptomatic patients with achalasia G II (Siewert classification) without previous treatment of an angoing randomized-controlled trial. Patients were blindy randomized to administrate: a) 8OU of BoTox were injected in four quadrants (1 ml in each quadrant-20 U/ml) (n=8) normal saline solution as placebo injected in the same way (n=5). Patientes who did not respond were retreated in an open design with the same schedule of BoTox. BoTox or placebe were injected directly into the lower esophageal sphincter (LES), located by manometric and endoscopic procedures, via sclerotherapy injector. Response to treatment was assessed by changes in symptoms score, weight, LES pressure, barium esophagograms and endoscopy. All determinations were repeated at basal and after 7-30-60 and 90 days of treatment. Post treatment response was considered positive if at one month, 3 of 4 parameters were improved. No evidence of response to BoTox were assessed in 3 patients. At 90 days, 10 patients remain well and data are as follows: (X + SD) symptoms score: (Pre: 3.23 + 0.44) (Post: 1.31 + 0.95); LES pressure (mmHg) (Pre: 53,15 + 66.31 + 7.49); per cent reduction of esophageal diameter 55 per cent (p< 0.0001) (pair T-test). Relaxation of LES did not change after treatment. There were no side effects related to BoTox injection. Conclusions: Endoscopic intrasphincteric BoTox injection is safe, simple and effective in the short term treatment for achalasia. Further studies are necessary for evaluation of long term effects.

Deteccion temprana de la enfermedad de membranas hialinas mediante un analisis rapido del aspirado gastrico en el recien nacido. / Early detection of hyaline membrane disease by means of rapid analysis of the gastric aspirate in newborn infants

Se describen los resultados del examen del aspirado gastrico para valorar la presencia de surfactante pulmonar en recien nacidos estudiando 112 casos entre prematuros, nacidos por cesarea, productos con APGAR bajo, sufrimiento fetal agudo, bajo peso, madre diabetica, producto gemelar.La prueba fue util en una gran cantidad de pacientes y esto permitio manejar en forma correcta a los pacientes evitando numerosos casos de muerte