DNA methylation during sexual embryogenesis and implications on the induction of somatic embryogenesis in Castanea sativa Miller.

From anthesis to mature seed formation, burrs from cross-pollinated adult Castanea sativa Miller trees were characterized and seven developmental stages defined based on macro and micromorphological traits. In order to get an insight into the involvement of epigenetic mechanisms in sexual embryogenesis and to define somatic embryogenesis induction capability, global DNA methylation and the somatic embryogenic competence were quantified. On cross-pollinated trees once fertilization takes place, at least one ovule per ovary becomes dominant, and transient DNA demethylation occurs coinciding with the start of the sexual embryogenic programme. Unfertilized ovules from the same cluster, which maintain their prior size, increase their methylation level and undergo degeneration. These results were validated using non-cross-pollinated trees and the asynchrony of flower receptivity. When testing in vitro somatic embryogenesis response of isolated dominant ovules and axes from zygotic embryos under cross-pollinated conditions, the highest competence was found for reaching seed maturity. Thus, a "developmental window" of somatic embryogenesis in chestnut has been characterized. It includes from fertilization to embryo maturity, and a transient decrease in methylation is necessary after fertilization for the development of the somatic embryogenesis response.

Assessment of genetic and epigenetic stability in long-term in vitro shoot culture of pea (Pisum sativum L.).

In vitro clonal propagation of plants should generate identical copies of the selected genotype. However, associated stress might result in a breakdown of control mechanisms and consequent instability of the genome. We have used several molecular methods to assess the genetic stability of long-term propagated (24 years) multiple shoot in vitro culture of pea (Pisum sativum L.). We focused on assessing the stability of repetitive sequences, such as simple sequence repeats (SSR) and retrotransposons, both comprising a large part of genome. No differences were found when seedlings (Co-2004) or original seed (Co-1982) controls and long-term or newly established in vitro (one subculture cycle) samples were investigated by the SSR, inter-repeats (ISSR) or inter-retrotransposon amplified polymorphism (IRAP) method. However, the more global amplified fragment length polymorphism (AFLP) and particularly the methylation sensitive MSAP methods detected 11 and 18% polymorphism among samples, respectively. Interestingly, investigation of the global cytosine methylation status by HPCE measurement revealed no statistically significant differences. Some evidence of retrotransposon re-arrangement was observed by sequence-specific amplification polymorphism. This occurred mostly in the abundant Ty3-gypsy type Cyclop element and to a smaller extent in the Ogre element. Alternatively, no polymorphism was detected among the PDR-1 element of the Ty1-copia type retrotransposon. Based on these results, multiple shoot culture of pea maintained over a long period may be considered as a true to type multiplication method of the original genotype.

Foreign bodies from the upper-aerodigestive tract of children in Puerto Rico.

The objective of this study was to investigate the incidence management, and complications of foreign bodies in the upper aerodigestive tract of children in Puerto Rico. The records of children admitted to the University Pediatric Hospital of Puerto Rico were revised from January 1, 1989 to December 31, 1994. 51 children had foreign body in their airway and 107 children had foreign body in their digestive trac (a total of 158 patients) These records were examined for age, gender, previous medical illness, clinical presentation, radiographic studies, removal technique, complications, and hospital stay. The most common age in both groups was 1 year old children. Of the 51 foreign bodies aspirations, 25 were boys and 26 were girls; and of the 107 ingestion, 67 were boys and 40 were girls. The most common times of the year were during the summer and winter months. The diagnosis of foreign body aspiration or ingestion was made in 6 hours or less in only 68 of the 158 cases. The most common signs were vomiting, coughing, and choking episode (44 cases). X-rays were positive in 146 cases (92.4%). The most common foreign body ingestion was coins and aspiration was peanuts. There were no complications on 129 cases (81.6%). The most common complication was pneumonia with 19 cases. The mean hospital stay was 3 days. In general, foreign body aspiration or ingestion are common events that can be prevented in the pediatric age. Parental education is important at this stage. If the event can't be prevented then a rapid management must be given to those patients with positive history of an adult witness of the event and a high level of suspicion for those patients with no reported event of choking or witness present.

[Late potentials analysis in patients with malignant ventricular arrhythmia]. / Análise de potenciais tardios em pacientes com arritmias ventriculares malignas.

PURPOSE: To assess the relationship between late potentials and spontaneous ventricular arrhythmias, organic heart disease, inducibility of arrhythmias at electrophysiological study and ejection fraction. METHODS: The population is comprised by 52 patients (41 men, 11 women with mean age 50 +/- 16 years) with spontaneous clinically documented ventricular tachycardia or ventricular fibrillation. An electrophysiological study was performed with conventional programmed stimulation. Within a week of the test a study of late potentials was also performed. RESULTS: Late potentials were documented in 73% of the patients with ventricular tachycardia and only in 17% of the patients with ventricular fibrillation. Sixty-eight percent of the patients with ischemic cardiopathy presented late potentials and in these, ventricular tachycardia was inducible in 93%. Only one from a group of 7 patients with ventricular arrhythmias and no organic heart disease, presented late potentials. In patients with late potentials, 84% have inducible ventricular tachycardia, but only 26% of patients without late potentials have inducible ventricular tachycardia. The incidence of late potentials was inversely correlated with left ventricular ejection fraction. CONCLUSION: The presence of late potentials was more frequent in patients with ventricular tachycardia than in patients with ventricular fibrillation. The presence of late potentials has a sensibility of 81.5% and a specificity of 78% to detect patients with inducible ventricular tachycardia.

[Mechanical complications of temporary pacemakers. Criteria for the diagnosis of perforation and dislodgement (author's transl)]. / Complicaciones mecánicas de los marcapasos temporales. Criterios diagnósticos de perforación y desenclavamiento.

The methods used in the early diagnosis of catheter malposition are compared in 31 patients with temporary endovenous pacemaker. In all cases the heart and the pericardial space were observed either at surgery or at post-mortem examination. The patients were divided into three groups: Group A: eight patients with proof of perforation of the free wall of the right ventricule. Group B: eight patients with dislodgement of the catheter and dysfunction of demand and stimulation without signs of perforation. Group C: fifteen patients without neither dysfunction or perforation. Clinical, radiological and electrocardiographic data were evaluated in each group. With the exception of cardiac tamponade, there were no clinical symptoms distinguishing perforation from dislodgement. Radiologically, only important changes in catheter position had diagnostic value. ECG changes were not diagnostic. Endocavitary ECG permits to locate the catheter with respect to the right ventricular wall. A good contact with the endocardium determines the appearance of a pathologic wave in the distal electrogram which diminishes or disappears after perforation or dislodgement. In the group A patients the QRS was predominantly positive, a feature that was not observed in the other two groups. When the catheter backed up to the atrium, high voltage atrial potentials were registered. Although the analysis of endocavitary recordings constitutes the most useful method to detect catheter malposition, only the total clinical, radiological, and electrocardiographic data provide a firm diagnosis.