Short term stability using phase plane

One of the most important problems in the study of transient stability of power systems is the determination of perturbation’s maximum time of permanence without losing the synchronism of the generators that feed the network. The problem is generally solved by either the application of the equal-area criterion or through numerical integration methods. In the present work, the phaseplane is proposed as an alternative tool to solve the above-mentioned problem with greater efficiency.Fil: Aromataris, Luis Miguel. Universidad Nacional de Río Cuarto. Facultad de Ingeniería; ArgentinaFil: Preidikman, Sergio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ingeniería; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Departamento de Estructuras; ArgentinaFil: Galetto, Marcos Antonio. Universidad Nacional de Río Cuarto. Facultad de Ingeniería; ArgentinaFil: Rinaudo, Fabian Dario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ingeniería; ArgentinaFil: Toledo, Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Misiones. Facultad de Ingeniería; Argentin

Hypercalcitoninemia is not Pathognomonic of Medullary Thyroid Carcinoma

Hypercalcitoninemia has frequently been reported as a marker for medullary thyroid carcinoma. Currently, calcitonin measurements are mostly useful in the evaluation of tumor size and progression, and as an index of biochemical improvement of medullary thyroid carcinomas. Although measurement of calcitonin is a highly sensitive method for the detection of medullary thyroid carcinoma, it presents a low specificity for this tumor. Several physiologic and pathologic conditions other than medullary thyroid carcinoma have been associated with increased levels of calcitonin. Several cases of thyroid nodules associated with increased values of calcitonin are not medullary thyroid carcinomas, but rather are related to other conditions, such as hypercalcemias, hypergastrinemias, neuroendocrine tumors, renal insufficiency, papillary and follicular thyroid carcinomas, and goiter. Furthermore, prolonged treatment with omeprazole (> 2–4 months), beta-blockers, glucocorticoids and potential secretagogues, have been associated with hypercalcitoninemia. An association between calcitonin levels and chronic auto-immune thyroiditis remains controversial. Patients with calcitonin levels >100 pg/mL have a high risk for medullary thyroid carcinoma (~90%–100%), whereas patients with values from 10 to 100 pg/mL (normal values: <8.5 pg/mL for men, < 5.0 pg/mL for women; immunochemiluminometric assay) have a <25% risk for medullary thyroid carcinoma

Membrane microdomain components of Histoplasma capsulatum yeast forms, and their role in alveolar macrophage infectivity

Analysis of membrane lipids of Histoplasma capsulatum showed that similar to 40% of fungal ergosterol is present in membrane microdomain fractions resistant to treatment with non-ionic detergent at 4 degrees C. Specific proteins were also enriched in these fractions, particularly Pma1p a yeast microdomain protein marker (a plasma membrane proton ATPase), a 30 kDa laminin-binding protein, and a 50 kDa protein recognized by anti-alpha 5-integrin antibody. To better understand the role of ergosterol-dependent microdomains in fungal biology and pathogenicity, H. capsulatum yeast forms were treated with a sterol chelator, methyl-beta-cyclodextrin (m beta CD). Removal of ergosterol by m beta CD incubation led to disorganization of ergosterol-enriched microdomains containing Pma1p and the 30 kDa protein, resulting in displacement of these proteins from detergent-insoluble to -soluble fractions in sucrose density gradient ultracentrifugation. m beta CD treatment did not displace/remove the 50 kDa alpha 5-integrin-like protein nor had effect on the organization of glycosphingolipids present in the detergent-resistant fractions. Ergosterol-enriched membrane microdomains were also shown to be important for infectivity of alveolar macrophages; after treatment of yeasts with m beta CD, macrophage infectivity was reduced by 45%. These findings suggest the existence of two populations of detergent-resistant membrane microdomains in H. capsulatum yeast forms: (i) ergosterol-independent microdomains rich in integrin-like proteins and glycosphingolipids, possibly involved in signal transduction; (ii) ergosterol-enriched microdomains containing Pma1p and the 30 kDa laminin-binding protein; ergosterol and/or the 30 kDa protein may be involved in macrophage infectivity. (C) 2011 Elsevier B.V. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Universidade Federal de São Paulo, Div Glycoconjugate Immunochem, Dept Biochem, Escola Paulista Med, BR-04023900 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Microbiol Immunol & Parasitol, Escola Paulista Med, BR-04023900 São Paulo, BrazilUniversidade Federal de São Paulo, Div Glycoconjugate Immunochem, Dept Biochem, Escola Paulista Med, BR-04023900 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Microbiol Immunol & Parasitol, Escola Paulista Med, BR-04023900 São Paulo, BrazilWeb of Scienc

Sporadic Medullary Thyroid Carcinoma: Clinical Data From A University Hospital

INTRODUCTION: Medullary thyroid carcinoma may occur in a sporadic (s-medullary thyroid carcinoma, 75%) or in a multiple endocrine neoplasia type 2 form (MEN2, 25%). These clinical forms differ in many ways, as s-medullary thyroid carcinoma cases are RET-negative in the germline and are typically diagnosed later than medullary thyroid carcinoma in MEN2 patients. In this study, a set of cases with s-medullary thyroid carcinoma are documented and explored. PURPOSE: To document the phenotypes observed in s-medullary thyroid carcinoma cases from a university group and to attempt to improve earlier diagnosis of s-medullary thyroid carcinoma. Some procedures for diagnostics are also recommended. METHOD: Patients (n=26) with apparent s-medullary thyroid carcinoma were studied. Their clinical data were reviewed and peripheral blood was collected and screened for RET germline mutations. RESULTS: The average age at diagnosis was 43.9 years (± 10.82 SD) and did not differ between males and females. Calcitonin levels were increased in all cases. Three patients presented values that were 100-fold greater than the normal upper limit. Most (61.54%) had values that were 20-fold below this limit. Carcinoembryonic antigen levels were high in 70.6% of cases. There was no significant association between age at diagnosis, basal calcitonin levels or time of disease onset with thyroid tumor size (0.6-15 cm). Routine thyroid cytology yielded disappointing diagnostic accuracy (46.7%) in this set of cases. After total thyroidectomy associated with extensive cervical lymph node resection, calcitonin values remained lower than 5 pg/mL for at least 12 months in eight of the cases (30.8%). Immunocyto- and histochemistry for calcitonin were positive in all analyzed cases. None of the 26 cases presented germline mutations in the classical hotspots of the RET proto-oncogene. CONCLUSION: Our cases were identified late. The basal calcitonin measurements and immunostaining for calcitonin were highly useful for diagnosing s-medullary thyroid carcinoma. The rate of complete patient recovery was low, and none of the parameters analyzed were useful predictors of the thyroid tumor size. Our findings support previous recommendations for routine serum calcitonin evaluation and immunostaining analysis involving single thyroid nodules

Structural diversity and biological significance of glycosphingolipids in pathogenic and opportunistic fungi

Glycosphingolipids (GSLs) are ubiquitous membrane components and have key roles in biological systems, acting as second messengers or modulators of signal transduction by affecting several events, ranging from cell adhesion, cell growth, cell motility, regulation of apoptosis and cell cycle. Over the last 20 years our laboratory and other research groups determined the glycan and ceramide structures of more than 20 GSLs from several pathogenic/opportunistic fungi, using a combination of gas chromatography, mass spectrometry, nuclear magnetic resonance as well as other immunochemical and biochemical techniques. Fungal GSLs can be divided in two major classes: neutral GSLs, galactosyl- and glucosylceramide (GIcCer), and acidic GSLs, the glycosylinositol-phosphorylceramides (GIPCs). Glycosyl structures in fungal GIPCs exhibited significant structural diversity and distinct composition when compared to mammalian GSLs, e.g., the expression of inositol-mannose and inositol-glucosamine cores and the terminal residue of beta-D-galactofuranose which are absent in mammalian cells. Studies performed by our group demonstrated that GIPC (Galf beta 6[Man alpha 3]Man alpha 2InsPCer) elicited in patients with paracoccidioidomycosis an immune response with production of antibodies directed to the terminal residue of beta-D-galactofuranose. Further studies also showed that inhibition of GIcCer biosynthetic pathways affects fungal colony formation, spore germination and hyphal growth, indicating that enzymes involved in GIcCer biosynthesis may represent promising targets for the therapy of fungal infections. Recently, it was shown that GIcCer and GIPCs are preferentially localized in membrane microdomains and monoclonal antibodies directed to these GSLs interfere in several fungal biological processes such as growth and morphological transition. This review focuses on glycan structures carried on sphingolipids of pathogenic/opportunistic fungi, and aspects of their biological significance are discussed.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Universidade Federal de São Paulo, Escola Paulista Med, Dept Biochem, Lab Glycoconjugate Immunochem, BR-04023900 São Paulo, BrazilUniv Santa Cecilia, Dept Pharmaceut Sci, Lab Nat Prod, Santos, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Biochem, Lab Glycoconjugate Immunochem, BR-04023900 São Paulo, BrazilWeb of Scienc

Interferência alelopática do chá de boldo-do-chile (Peumus boldus Molina, Monimiaceae) sobre sementes de alface e pepino

Boldo (Peumus boldus Molina) is a tree of the Monimiaceae family. It is used by the people to treat several diseases, and presents diverse products such as: a bactericide, an insecticide and an allelopathy. The aim of this study was to evaluate the potential of the allelopatic activity of the boldo infusion on the germination and initial development of lettuce and cucumber seeds. The bioassay was conducted in an environmental temperature controlled laboratory, through a completely randomized design method with five repetitions. The boldo infusion was obtained in the local commerce, and prepared with boiling distillated water, diluted to the proportions of 25, 50, 75, and 100%. The control was only distillated water. The evaluation parameters used were germination percentage, germination speed index (measured each 24 hours) and root length (measured with a caliper rule on the last day of the experiment). Regarding germination percentage, we found significant values only using 100% treatment of cucumber seeds. The germination of lettuce seeds was inhibited throughout all of the treatments with boldo infusion. The germination speed index of cucumber seeds was influenced throughout all of the treatments. The root length of cucumber seeds was inhibited with all treatments and significantly different if compared with the control. Boldo infusion presented allelopathic activity on the seeds of lettuce and cucumber, showing the presence of bioactive molecules which can serve to subsidize new studies.O boldo-do-chile é uma planta arbórea pertencente à família Monimiaceae. É utilizado pela população para diversas enfermidades e apresenta atividade bactericida, inseticida e alelopática. O objetivo deste estudo foi avaliar o potencial de atividade alelopática do chá de boldo-do-chile sobre a germinação e desenvolvimento inicial de sementes de alface e pepino. O bioensaio foi conduzido em laboratório sob temperatura ambiente, em delineamento inteiramente casualizado com cinco repetições. O chá de boldo-do-chile foi adquirido no comércio local, preparado com água destilada fervente, diluído nas proporções de 25, 50, 75 e 100%. Apenas água destilada foi utilizada para controle. A porcentagem de germinação, índice de velocidade de germinação e comprimento da raiz foram utilizados como parâmetros de avaliação alelopática. Para a porcentagem de germinação, foram verificados valores significativos na germinação de sementes de pepino no tratamento 100%. A germinação de sementes de alface sofreu inibição total em todos os tratamentos com chá de boldo-do-chile. O índice de velocidade de germinação de sementes de pepino submetidas ao chá de boldo-do-chile sofreu influência significativa em todos os tratamentos em relação ao controle. As sementes de pepino submetidas ao chá de boldo-do-chile sofreram inibição no comprimento da raiz em todos os tratamentos avaliados, apresentando valores significativos em comparação ao controle. O chá de boldo-do-chile apresentou atividade alelopática sobre as sementes de alface e pepino, demonstrando a presença de moléculas bioativas que servem de subsídio para novos estudos

Total parathyroidectomy in a large cohort of cases with hyperparathyroidism associated with multiple endocrine neoplasia type 1: experience from a single academic center

Most cases of sporadic primary hyperparathyroidism present disturbances in a single parathyroid gland and the surgery of choice is adenomectomy. Conversely, hyperparathyroidism associated with multiple endocrine neoplasia type 1 (hyperparathyroidism/multiple endocrine neoplasia type 1) is an asynchronic, asymmetrical multiglandular disease and it is surgically approached by either subtotal parathyroidectomy or total parathyroidectomy followed by parathyroid auto-implant to the forearm. In skilful hands, the efficacy of both approaches is similar and both should be complemented by prophylactic thymectomy

Disruption of the glucosylceramide biosynthetic pathway in Aspergillus nidulans and Aspergillus fumigatus by inhibitors of UDP-Glc : ceramide glucosyltransferase strongly affects spore germination, cell cycle, and hyphal growth

The opportunistic mycopathogen Aspergillus fumigatus expresses both glucosylceramide and galactosylceramide (GlcCer and GalCer), but their functional significance in Aspergillus species is unknown. We here identified and characterized a GlcCer from Aspergillus nidulans, a non-pathogenic model fungus. Involvement of GlcCer in fungal development was tested on both species using a family of compounds known to inhibit GlcCer synthase in mammals. Two analogs, D-threo-1-phenyl-2-palmitoyl-3-pyrrolidinopropanol (P4) and D-threo-3',4'-ethylenedioxy-P4, strongly inhibited germination and hyphal growth. Neutral lipids from A. fumigatus cultured in the presence of these inhibitors displayed a significantly reduced GlcCer/GalCer ratio. These results suggest that synthesis of GlcCer is essential for normal development of A. fumigatus and A. nidulans. (C) 2002 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.Univ New Hampshire, Dept Chem, Durham, NH 03824 USAUniv Georgia, Dept Bot, Athens, GA 30602 USAUniversidade Federal de São Paulo, Dept Biochem, Escola Paulista Med, BR-04023900 São Paulo, BrazilUniv Michigan, Med Ctr, Dept Internal Med, Div Nephrol, Ann Arbor, MI 48109 USAUniv Georgia, Complex Carbohydrate Res Ctr, Athens, GA 30602 USAUniv Georgia, Dept Biochem & Mol Biol, Athens, GA 30602 USAUniversidade Federal de São Paulo, Dept Biochem, Escola Paulista Med, BR-04023900 São Paulo, BrazilWeb of Scienc

Phospholipase-D activity and inflammatory response induced by brown spider dermonecrotic toxin: Endothelial cell membrane phospholipids as targets for toxicity

Brown spider dermonecrotic toxins (phospholipases-D) are the most well-characterized biochemical constituents of Loxosceles spp. venom. Recombinant forms are capable of reproducing most cutaneous and systemic manifestations such as dermonecrotic lesions, hematological disorders, and renal failure. There is currently no direct confirmation for a relationship between dermonecrosis and inflammation induced by dermonecrotic toxins and their enzymatic activity. We modified a toxin isoform by site-directed mutagenesis to determine if phospholipase-D activity is directly related to these biological effects. the mutated toxin contains an alanine substitution for a histidine residue at position 12 (in the conserved catalytic domain of Loxosceles intermedia Recombinant Dermonecrotic Toxin - LiRecDT1). LiRecDT1H12A sphingomyelinase activity was drastically reduced, despite the fact that circular dichroism analysis demonstrated similar spectra for both toxin isoforms, confirming that the mutation did not change general secondary structures of the molecule or its stability. Antisera against whole venom and LiRecDT1 showed cross-reactivity to both recombinant toxins by ELISA and immunoblotting. Dermonecrosis was abolished by the mutation, and rabbit skin revealed a decreased inflammatory response to LiRecDT1H12A compared to LiRecDT1. Residual phospholipase activity was observed with increasing concentrations of LiRecDT1H12A by dermonecrosis and fluorometric measurement in vitro. Lipid arrays showed that the mutated toxin has an affinity for the same lipids LiRecDT1, and both toxins were detected on RAEC cell surfaces. Data from in vitro choline release and HPTLC analyses of LiRecDT1-treated purified phospholipids and RAEC membrane detergent-extracts corroborate with the morphological changes. These data suggest a phospholipase-D dependent mechanism of toxicity, which has no substrate specificity and thus utilizes a broad range of bioactive lipids. (C) 2010 Elsevier B.V. All rights reserved.Secretaria de Estado de CienciaTecnologia e Ensino Superior (SETI) do ParanaFundacao Araucaria-PRFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Univ Fed Parana, Dept Cell Biol, BR-81531990 Curitiba, Parana, BrazilUniversidade Federal de São Paulo, Dept Biochem, São Paulo, BrazilUniv Estadual Ponta Grossa, Dept Struct Mol Biol & Genet, Ponta Grossa, BrazilCatholic Univ Parana, Hlth & Biol Sci Inst, Curitiba, Parana, BrazilUniversidade Federal de São Paulo, Dept Biochem, São Paulo, BrazilWeb of Scienc