65 research outputs found

    New perspectives in cadmium toxicity: an introduction

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    Renal involvement in mitochondrial cytopathies

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    Mitochondrial cytopathies constitute a group of rare diseases that are characterized by their frequent multisystemic involvement, extreme variability of phenotype and complex genetics. In children, renal involvement is frequent and probably underestimated. The most frequent renal symptom is a tubular defect that, in most severe forms, corresponds to a complete De Toni-Debré-Fanconi syndrome. Incomplete proximal tubular defects and other tubular diseases have also been reported. In rare cases, patients present with chronic tubulo-interstitial nephritis or cystic renal diseases. Finally, a group of patients develop primarily a glomerular disease. These patients correspond to sporadic case reports or can be classified into two major defects, namely 3243 A>G tRNALEU mutations and coenzyme Q10 biosynthesis defects. The latter group is particularly important because it represents the only treatable renal mitochondrial defect. In this Educational Review, the principal characteristics of these diseases and the main diagnostic approaches are summarized

    The role of phosphatidylinositides in stimulus-secretion coupling in the exocrine pancreas

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    Cell activation of different cell types is accompanied by receptor-mediated stimulation of phospholipase C and a consequent breakdown of phosphatidylinositol 4,5-bisphosphate. Evidence suggests that GTP-binding proteins are involved in this signal transduction mechanism, which couples receptors to phospholipase C. Both the hydrolysis products diacylglycerol (DG) and inositol 1,4,5-trisphosphate (IP3) are intracellular messengers for cellular responses such as secretion, as illustrated by the pancreatic acinar cell. IP3 releases Ca2+ from a nonmitochondrial Ca2+ pool likely to be the endoplasmic reticulum (ER). This Ca2+ release leads to a transient rise in the cytosolic free Ca2+ concentration from approximately 100 to approximately 800 nmol/liter, by which enzyme secretion is initiated. For sustained secretion, Ca2+ influx into the cell is necessary to keep the cytosolic free Ca2+ concentration at a slightly elevated level. Activation of protein kinase C by DG and Ca2+ seems to play a major role in the second, sustained phase of secretion. Ca2+ reuptake into the ER and Ca2+ extrusion from the cell are achieved by (Ca2+ + Mg2+)-ATPase in both the ER and the plasma membrane as well as by an Na+/Ca2+ exchange in the latter. In the final step of exocytosis, protein phosphorylation by Ca2+-, DG-, and cAMP-dependent protein kinases is probably involved

    Empirical Studies of Object-Oriented Artifacts, Methods, and Processes: State of The Art and Future Directions

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    This paper summarizes the results of a working group at the Empirical Studies of Softwar
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