Hacia un nuevo VIII par: alternativas de baja complejidad / Towards a new vestibular assessment: low complexity alternatives

Introducción: El examen funcional del VIII par, mediante la prueba calórica permite conocer la función del canal semicircular horizontal, dejando de lado la evaluación de otras estructuras como el complejo utrículo-sacular. Objetivo: Evaluar el rendimiento diagnóstico de pruebas vestibulares de bajo costo y complejidad cefálico para suplir esta falencia. Material y método: En 34 pacientes con indicación de estudio funcional de VIII par se realizaron, además de las pruebas tradicionales, el test visual subjetivo vertical mediante prueba del balde, la prueba de impulso cefálico a ojo desnudo, y la aplicación del cuestionario de sintomatología "Dizziness Handicap Inventory". Resultados: Considerando el VIII par clásico como patrón de oro, se encuentra evidencia objetiva de patología en 50% de la muestra. Con la incorporación de los nuevos exámenes esta cifra aumenta a 85%. Se realizó análisis de discrepancia sobre pacientes con resultados normales en el estudio tradicional, pero anormal según los nuevos exámenes. El 100% de dicho grupo presenta una puntuación patológica en el cuestionario de síntomas. Más aún, los valores de desviación de verticalidad correlacionaron fuertemente con la puntuación de sintomatología (r =0,79; p =0,002). Conclusiones: El análisis de discrepancia sugiere que los nuevos exámenes son confiables en identificar patología en el estudio. Incluir en el estudio tradicional del VIII par pruebas de baja complejidad y corta duración (menos de 5 minutos en su conjunto) podría aumentar el rendimiento diagnóstico del estudio del equilibrio en hasta 35%.

Introduction: Traditionally, the assessment of vestibular function is based on the caloric test. This procedure assesses mainly the horizontal semicircular canal function, leaving other vestibular structures aside, such as the utricule-saccule complex. Aim: To assess the diagnostic performance low complexity tests to compensate for these issues. Material and methods: 34 patients with indication for vestibular assessment were recruited. In addition to traditional testing (caloric test and postural provocation maneuvers), the mentioned Subjective Visual Vertical and Head Impulse tests were applied alongside the Dizziness Handicap Inventory for vestibular symptoms. Results: Considering caloric testing and Dix-Hallpike maneuvers as gold standard, 50% of the sample presented an objective cause of their symptomatology. When including the new test, this value increases to 85%. A discrepancy analysis was conducted on the group with normal traditional tests and abnormal new tests. 100% of this group showed symptoms score above pathological levels. Furthermore, there was a strong relationship between deviation on the Visual Vertical test and symptomatology (r =0,79; p =0,002). Conclusion: The discrepancy analysis suggests that the new tests are reliable in determining pathology on this study. It these test are included to traditional testing, diagnostic performance may increase up to 35%.

Identification and characterization of a nodH ortholog from the alfalfa-nodulating Or191-like rhizobia.

Nodulation of Medicago sativa (alfalfa) is known to be restricted to Sinorhizobium meliloti and a few other rhizobia that include the poorly characterized isolates related to Rhizobium sp. strain Or191. Distinctive features of the symbiosis between alfalfa and S. meliloti are the marked specificity from the plant to the bacteria and the strict requirement for the presence of sulfated lipochitooligosaccharides (Nod factors [NFs]) at its reducing end. Here, we present evidence of the presence of a functional nodH-encoded NF sulfotransferase in the Or191-like rhizobia. The nodH gene, present in single copy, maps to a high molecular weight megaplasmid. As in S. meliloti, a nodF homolog was identified immediately upstream of nodH that was transcribed in the opposite direction (local synteny). This novel nodH ortholog was cloned and shown to restore both NF sulfation and the Nif+Fix+ phenotypes when introduced into an S. meliloti nodH mutant. Unexpectedly, however, nodH disruption in the Or191-like bacteria did not abolish their ability to nodulate alfalfa, resulting instead in a severely delayed nodulation. In agreement with evidence from other authors, the nodH sequence analysis strongly supports the idea that the Or191-like rhizobia most likely represent a genetic mosaic resulting from the horizontal transfer of symbiotic genes from a sinorhizobial megaplasmid to a not yet clearly identified ancestor.

Rhizosphere-bacterial community in Eperua falcata (Caesalpiniaceae) a putative nitrogen-fixing tree from French Guiana rainforest.

The rainforest of French Guiana is still largely unaffected by human activity. Various pristine sites like the Paracou Research Station are devoted to study this tropical ecosystem. We used culture-independent techniques, like polymerase chain reaction-temperature gradient gel electrophoresis, and construction of clone libraries of partial 16S rRNA and nifH genes, to analyze the composition of the bacterial community in the rhizosphere of mature trees of Eperua falcata and Dicorynia guianensis, both species within the Caesalpiniaceae family. E. falcata is one of the more abundant pioneer tree species in this ecosystem and so far, no root nodules have ever been found. However, its nitrogen-fixing status is regarded as "uncertain", whereas D. guianensis is clearly considered a non-nitrogen-fixing plant. The rhizospheres of these mature trees contain specific bacterial communities, including several currently found uncultured microorganisms. In these communities, there are putative nitrogen-fixing bacteria specifically associated to each tree: D. guianensis harbors several Rhizobium spp. and E. falcata members of the genera Burkholderia and Bradyrhizobium. In addition, nifH sequences in the rhizosphere of the latter tree were very diverse. Retrieved sequences were related to bacteria belonging to the alpha-, beta-, and gamma-Proteobacteria in the E. falcata rhizoplane, whereas only two sequences related to gamma-Proteobacteria were found in D. guianensis. Differences in the bacterial communities and the abundance and diversity of nifH sequences in E. falcata rhizosphere suggest that this tree could obtain nitrogen through a nonnodulating bacterial interaction.

Mesorhizobium chacoense sp. nov., a novel species that nodulates Prosopis alba in the Chaco Arido region (Argentina).

Low-molecular-weight RNA analysis was performed for the identification and classification of 20 Argentinian strains isolated from the root nodules of Prosopis alba. SDS-PAGE of total cellular proteins, determination of the DNA base composition, DNA-DNA reassociation experiments and physiological and biochemical tests were also carried out for these strains and the whole 16S rRNA gene was sequenced from one of the strains, strain LMG 19008T. Results of the genotypic and phenotypic characterization showed that the strains isolated in this study belong to a group that clustered in the genus Mesorhizobium. The results of DNA-DNA hybridizations showed that this group is a novel species of this genus. The name Mesorhizobium chacoense sp. nov. is proposed for this species. The type strain is LMG 19008T (= CECT 5336T).

Isolation and characterization of alfalfa-nodulating rhizobia present in acidic soils of central argentina and uruguay

We describe the isolation and characterization of alfalfa-nodulating rhizobia from acid soils of different locations in Central Argentina and Uruguay. A collection of 465 isolates was assembled, and the rhizobia were characterized for acid tolerance. Growth tests revealed the existence of 15 acid-tolerant (AT) isolates which were able to grow at pH 5.0 and formed nodules in alfalfa with a low rate of nitrogen fixation. Analysis of those isolates, including partial sequencing of the genes encoding 16S rRNA and genomic PCR-fingerprinting with MBOREP1 and BOXC1 primers, demonstrated that the new isolates share a genetic background closely related to that of the previously reported Rhizobium sp. Or191 recovered from an acid soil in Oregon (B. D. Eardly, J. P. Young, and R. K. Selander, Appl. Environ. Microbiol. 58:1809-1815, 1992). Growth curves, melanin production, temperature tolerance, and megaplasmid profiles of the AT isolates were all coincident with these characteristics in strain Or191. In addition to the ability of all of these strains to nodulate alfalfa (Medicago sativa) inefficiently, the AT isolates also nodulated the common bean and Leucaena leucocephala, showing an extended host range for nodulation of legumes. In alfalfa, the time course of nodule formation by the AT isolate LPU 83 showed a continued nodulation restricted to the emerging secondary roots, which was probably related to the low rate of nitrogen fixation by the largely ineffective nodules. Results demonstrate the complexity of the rhizobial populations present in the acidic soils represented by a main group of N2-fixing rhizobia and a second group of ineffective and less-predominant isolates related to the AT strain Or191.

Tratamiento quirurgico del reflujo gastroesofagico, esofagitis peptica y sus complicaciones. / Surgical treatment of gastroesophageal reflux, peptic esophagitis and its complications

El conocimiento de la fisiologia del esofago y la fisiopatologia del reflujo gastroesofagico, el desarrollo de pruebas funcionales esofagicas y el diseno de procedimientos quirurgicos efectivos, ha dado como resultado un adecuado tratamiento del reflujo gastroesofagico y sus complicaciones. Revisamos la experiencia con cuatro procedimientos: 1 - Funduplicacion de Nissen. 2 - Funduplicacion parcial de Belsey.3 - Gastropexia posterior de Hill. 4- Funduplastia posterior de Guarner. Las recidivas del Nissen son del 5% y como complicacion tiene un 50% de "sindrome de bloqueo". Para el Belsey y el Hill las fallas son del 12%. La funduplastia posterior muestra resultados semejantes al Nissen, pero con un sindrome de bloqueo de 2.2%. Los procedimientos quirurgicos para el tratamiento de la estenosis peptica se dividen en dos grupos: Metodos antireflujo y resectivos. Los buenos resultados varian del 70-85%

Acalasia del esofago. / Achalasia of the esophagus

La etiologia de la acalasia es desconocida sin embargo, es uno de los desordenes motores del esofago que ha recibido mayor atencion en su estudio.Durante muchos anos se trato a base de dialataciones esofagicas periodicas. Durante el ultimo cuarto de siglo se ha generalizado el manejo quirurgico. En este trabajo, se hace una revision de los resultados obtenidos con el tratamiento de 145 pacientes, de los cuales 40 fueron dilatados exclusivamente y 129 fueron intervenidos quirurgicamente.Los 40 pacientes dilatados tuvieron 25% de exito. Los enfermos a quienes se les practico intervencion quirurgica como primera instancia, tuvieron un 95% de buenos resultados. Hubo 129 pacientes que fueron operados, entre los cuales 24 enfermos habian sido dilatados previamente. El porciento de exito en estos fue de 91.7%. Se concluye que el mejor tratamiento de la Acalasia es el quirurgico. Se hace una revision de los procedimientos que pueden utilizarse, analizando las ventajas y desventajas de cada uno de ellos