Acute toxicity of chlorpyrifos to the non-target organism Cnesterodon decemmaculatus

Chlorpyrifos is the most used insecticide in Argentina. Cnesterodon decemmaculatus is a widely distributed, endemic fish from Neotropical America. It attains high densities in the shallow water assemblages of Argentina and Brazil. The aim of this study was to assess the acute toxicity of chlorpyrifos to C. decemmaculatus. The mean 96-h LC₅₀ of three independent determinations was 105.3 (±?3.1) μg/L. Sublethal effects were observed. Swimming behavioral changes at each chlorpyrifos exposure concentration were reported. C. decemmaculatus represents a good model for ecotoxicological risk assessment.     

Monotherapy with enoxaparin for the prevention of recurrent venous thromboembolism.

This study aimed to determine whether a weight-adjusted dose of subcutaneous enoxaparin is as effective and safe as oral acenocoumarol for the secondary prophylaxis of pulmonary embolism. Three hundred and eighty consecutive noncancer outpatients hospitalized with an episode of symptomatic pulmonary embolism selected treatment with acenocoumarol or enoxaparin at a dose of 1 mg/kg once daily after being informed of the type of administration and expected frequency of laboratory monitoring for both medicinal products. Endpoints were symptomatic recurrent thromboembolic events evaluated by standard objective testing, and a composite endpoint of recurrent venous thromboembolism, major bleeding, and death from any cause. One hundred and ninety-nine patients (52%) chose acenocoumarol therapy and 181 chose enoxaparin monotherapy. Four patients in the enoxaparin group (2.2%) and six patients in the acenocoumarol group (3%) had an objective thromboembolic recurrence (hazard ratio, 1.35; 95% confidence interval, 0.38-4.79; P = 0.64). Nine patients in the enoxaparin group (5.0%) had a hemorrhagic complication compared with 11 in the acenocoumarol group (5.5%) (P = 0.81). The hospital length of stay was shorter with enoxaparin compared with acenocoumarol (11 versus 16 days, P = 0.0001). Enoxaparin is as effective and safe as acenocoumarol in the secondary prevention of recurrent thromboembolic disease and is associated with shorter hospitalization.     

Antineutrophil cytoplasmic antibodies (ANCA) in idiopathic pulmonary hemosiderosis

Four children were diagnosed with idiopathic pulmonary hemosiderosis (IPH), over a period of 4 years. Retrospectively, antineutrophil cytoplasmic antibodies (ANCA) were studied by indirect immunofluorescence (IIF) and ELISA in 18 sera from these patients, stored at -20°C. ANCA-positive sera, from 1/20 to 1/1, 200 dilution, were found in 3/4 of the patients, by IIF. The patient with the highest titre of ANCA died 3 months later during an acute crisis, the other two patients need a minimal dose of steroids. In one case only, a patient who is still without treatment, had no ANCA. The antibodies anti-myeloperoxidase and anti-pro-teinase-3 were negative or at border line levels. Rheumatoid factor, anti-nuclear (Hep-2), anti-endomysial, anti-reticulin and antibasement membrane antibodies were negative in all sera. The surviving patients were followed-up for more than 10 years with no systemic or renal disease appearences. The presence of serum ANCA may help to classify children with pulmonary haemorrhage and may have a prognostic value.     

Meningitis due to mixed infection with penicillin-resistant and penicillin-susceptible strains of Streptococcus pneumoniae

Streptococcus pneumoniae is the major cause of bacterial meningitis. We report a case of meningitis due to a mixed infection with two distinct strains of S. pneumoniae: one penicillin-resistant strain of serotype 9V and one penicillin-susceptible strain of serotype 7. The two strains exhibited different pulsed-field gel electrophoresis profiles.     

Comparing bacterial genomes through conservation profiles

We constructed two-dimensional representations of profiles of gene conservation across different genomes using the genome of Escherichia coli as a model. These profiles permit both the visualization at the genome level of different traits in the organism studied and, at the same time, reveal features related to the genomes analyzed (such as defective genomes or genomes that lack a particular system). Conserved genes are not uniformly distributed along the E. coli genome but tend to cluster together. The study of gene distribution patterns across genomes is important for the understanding of how sets of genes seem to be dependent on each other, probably having some functional link. This provides additional evidence that can be used for the elucidation of the function of unannotated genes. Clustering these patterns produces families of genes which can be arranged in a hierarchy of closeness. In this way, functions can be defined at different levels of generality depending on the level of the hierarchy that is studied. The combined study of conservation and phenotypic traits opens up the possibility of defining phenotype/genotype associations, and ultimately inferring the gene or genes responsible for a particular trait.     

Distribution of glycoconjugates during cochlea development in mice: light microscopic lectin study

During development, different epithelial cells in the mouse cochlea express different cell surface glycoconjugates, which may reflect membrane specialization. Some of the lectins tested in this study (SBA, succ-WGA, and PSA) labeled the sensory cells of the cochlea around birth. Other lectins (WGA, Con A, RCA-II, and PHA-E) labeled surfaces of the sensory cells, particularly the stereocilia, from early stages of development (gestation day (GD) 16) through 21 days after birth. These may be adhesion molecules needed to attach the newly forming tectorial membrane (TM) to the stereocilia. Lectin staining of the developing TM revealed that the substructures of the TM are biochemically distinct. Lectin staining also showed the temporal sequence of the expression of cytoplasmic glycoconjugates of the cochlear epithelium during development. Biochemical changes during development are probably the result of different cells being involved in the production of glycoconjugates, and may have functional significance, specifically with regard to the expression of adhesion and/or signaling molecules.     

The gene DIS2S1 is essential in Saccharomyces cerevisiae and is involved in glycogen phosphorylase activation

Summary S. cerevisiae gene DIS2S1, which codes for a protein very similar to the catalytic subunit of mammalian protein phosphatase 1, was disrupted in vitro. Diploid yeast cells were transformed and sporulated. Tetrad analysis demonstrated that disruption of DIS2S1 is lethal for the cell. Glycogen phosphorylase a and glycogen synthase activity ratio were measured in diploids carrying a disrupted allele of the gene. Phosphorylase was dramatically activated in mutant cells but, under the same conditions, glycogen synthase activity was essentially identical in both mutant and wild-type cells.     

Primary hepatic leiomyosarcoma in a child with the acquired immunodeficiency syndrome.

We report the first case of acquired immunodeficiency syndrome (AIDS)-related primary hepatic leiomyosarcoma in a 9-year-old girl. The pathologic diagnosis was made on a partial hepatectomy specimen and was confirmed by immunohistochemistry and electron microscopy. No human immunodeficiency virus-related nucleic acid was identified in tumor cells by in situ hybridization. Review of the AIDS-related literature reveals a rising incidence of tumors of smooth muscle origin in human immunodeficiency virus-infected patients. This case study details the eighth pediatric AIDS patient with a tumor of smooth muscle origin and represents the 20th and the youngest patient with primary hepatic leiomyosarcoma to be reported in the world literature.     

Extracellular taurine increase in rat hippocampus evoked by specific glutamate receptor activation is related to the excitatory potency of glutamate agonists

Taurine increases in brain extracellular space due to glutamate agonists were studied in vivo in the rat hippocampus using a dialysis technique, both in the absence and in the presence of glutamate receptor antagonists. Extracellular taurine levels increased during perfusions of agonists, listed in descending order of potency: kainate (KA), N-methyl-D-aspartate (NMDA), and quisqualate (QA). While taurine increases due to KA or QA perfusions were inhibited by 6,7-dinitro-quinoxaline-2,3-dione (DNQX), those induced by NMDA were abolished in the presence of 3-(carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP). These results indicate that increases in extracellular taurine levels evoked by NMDA, KA or QA in the rat hippocampus are caused by activation of their specific receptors. Field potentials, concomitantly recorded, were quickly abolished during NMDA or KA perfusions (0.1 mM), while QA (0.25 mM) induced the appearance of bicuculline-like evoked responses. Since taurine has been proposed as an osmoregulatory substance in the rat brain, and cell swelling is known to be an early component of glutamate agonists neurotoxicity, the increases in extracellular taurine reported here could be due to taurine released through an osmoregulatory process, counteracting the neurotoxic cellular oedema induced by glutamate agonists.