Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0025362 (mental retardation)
 15,878 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Various nuclear analytical methods have been developed and applied to determine the elemental composition of calcified tissues (teeth and bones). Fluorine was determined by prompt gamma-activation analysis through the 19F(rho, alpha, gamma)16O reaction. Carbon was measured by activation analysis with 3He ions, and the technique of proton-induced x-ray emission (PIXE) was applied to simultaneously determine calcium, phosphorus, and trace elements in well-documented teeth. Dental hard tissues (enamel, dentine, cementum, and their junctions) and different parts of the same tissue were examined separately. With the use of a proton microprobe, we measured the surface distribution of fluorine and other elements on and around carious lesions on the enamel. The depth profiles of fluorine, and other elements were also measured right up to the amelodentin junction. We discuss the development of various nuclear techniques and their applications, mainly in the field of dental health and to some extent in the study of the role of lead in mental retardation. We do not mention other important areas of calcified tissue research where these techniques could play an important role (e.g., in accurate and nondestructive measurements of calcium, phosphorus, and other elements in small bone biopsies taken from patients with metabolic bone disorders). No suitable chemical method appears to be available that can provide accurate assessment of calcium, phosphorus, and other trace elements in small bone biopsies. Moreover, the nondestructive nature of the nuclear methods has an extra advantage in that the bone samples, which are normally rather small in quantity, subsequently can be used for histologic examination.
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PMID:Nuclear analytical methods in calcified tissue research. 874 17

Mucopolysaccharidosis IIIA (MPS IIIA) is a lysosomal storage disorder caused by a deficiency in the activity of the lysosomal hydrolase, sulphamidase, an enzyme involved in the degradation of heparan sulphate. MPS IIIA patients exhibit progressive mental retardation and behavioural disturbance. While neuropathology is the major clinical problem in MPS IIIA patients, there is little understanding of how lysosomal storage generates this phenotype. As reduced neuronal communication can underlie cognitive deficiencies, we investigated whether the secretion of neurotransmitters is altered in MPS IIIA mice; utilising adrenal chromaffin cells, a classical model for studying secretion via exocytosis. MPS IIIA chromaffin cells displayed heparan sulphate storage and electron microscopy revealed large electron-lucent storage compartments. There were also increased numbers of large/elongated chromaffin granules, with a morphology that was similar to immature secretory granules. Carbon fibre amperometry illustrated a significant decrease in the number of exocytotic events for MPS IIIA, when compared to control chromaffin cells. However, there were no changes in the kinetics of release, the amount of catecholamine released per exocytotic event, or the amount of Ca(2+) entry upon stimulation. The increased number of large/elongated granules and reduced number of exocytotic events suggests that either the biogenesis and/or the cell surface docking and fusion potential of these vesicles is impaired in MPS IIIA. If this also occurs in central nervous system neurons, the reduction in neurotransmitter release could help to explain the development of neuropathology in MPS IIIA.
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PMID:Exocytosis is impaired in mucopolysaccharidosis IIIA mouse chromaffin cells. 2302 19