Complicaciones abdominales de los catéteres de derivación ventrículo-peritoneal

En un lapso de doce años, fueron intervenidos 31 niños por diversos tipos de hidrocefalia mediante la colocación de un catéter de derivación ventrículo- peritoneal.The records of 31 children with ventriculo- peritoneal shunt admited in the last 12 years were reviewed

Chromosomal variability and evolution in the tribe Phyllotini (Rodentia, Cricetidae, Sigmodontinae)

Sigmodontinae is a group of rodents with a rich and complex diversification in South America. Among them, the tribe Phyllotini comprises at least ten genera and exhibits high chromosome variability. It was proposed that chromosome evolution in mammals is influenced by centromeric meiotic drive (CMD). This mechanism of chromosome transmission generates a bimodal distribution of karyotypes, which are either mostly acrocentric or mostly biarmed. Here, we reviewed and analyzed chromosome data from Phyllotini to contrast them with that predicted by the CMD model. Additionally, we analyzed the chromosome data in a phylogenetic framework. When only one karyotype was considered per polymorphic species, the distribution resembles the CMD model, although it is not completely bimodal. The position of most polymorphic species in the center of the distribution and the presence of XY1Y2 chromosomes in a species with exclusively biarmed autosomes suggested that the CMD model is applicable to some particular species. Within a phylogenetic framework, some genera are characterized by high fundamental numbers (FNs), such as Calomys, Phyllotis, and Andalgalomys, and others by low FN (Loxodontomys, Auliscomys). This suggests that FN is a good marker for inferring some intra- and intergeneric relationships. However, the chromosome data are not coincident with the close molecular relationship obtained between Andalgalomys and Salinomys, because these species have respectively the maximum and minimum diploid number (2n) found in the tribe. There are 87 described karyotypes, but only one species has 2n�=�52, considered ancestral for sigmodontines, or 2n�=�70, proposed as ancestral for phyllotines. This suggests a major chromosomal restructuring at the base of the phyllotine radiation.Fil: Lanzone, Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas; ArgentinaFil: Cardozo, Dario Elbio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas; ArgentinaFil: Sanchez, Denisse Mavis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas; ArgentinaFil: Marti, Dardo Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas; ArgentinaFil: Ojeda, Ricardo Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; Argentin

Multivariate discrimination among cryptic mites of the genus Androlaelaps (Acari: Mesostigmata: Laelapidae) parasitic of sympatric akodontine rodents (Cricetidae: Sigmodontinae) in northeastern Argentina: possible evidence of host switch followed by speciation, with the description of two new species

Laelapids are among the most common ectoparasites of rodents. Currently, it is under discussion whether there is a single polixenous species that parasites a variety of hosts, or whether there are cryptic species highly host specific. Herein, multivariate morphometric analyses of cryptic sympatric laelapids of the genus Androlaelaps allowed us to identify different species. These species are specific of their akodontine hosts, Akodon montensis and Thaptomys nigrita, in localities situated in northeastern Argentina. In addition, we analyzed similar laelapids associated with the akodontines Deltamys kempi and Akodon cursor. Using principle component analyses we differentiated four laelapid species, each one host specific, independent of sympatry of the hosts, and without geographical variation. From these four species, we described two new species (Androlaelaps navonae n. sp. and Androlaelaps wingei n. sp.). We determined the four species based on a range of variations in several characters, mainly size. These four laelapid species belong to the Androlaelaps rotundus species group, specific to akodontines. These species are very similar among them but differ from the remainder species of the group by their small size, distance between j6 setae similar to the distance between the z5 setae, strong ventral setae, opisthogaster with 13 pairs of strong setae (one close to the distal margin of epigynal shield), and anal shield wider than long. Further studies will elucidate whether they constitute a new laelapid genus. Phylogenetic and ecological factors influencing host-specificity are discussed, and we propose that host colonization could have taken place by host switching of a single laelapid species among rodent species, followed by speciation.Fil: Lareschi, Marcela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Galliari, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; Argentin