RESUMO
A structural study of glass-ionomer cement (GIC) dental restoratives has been completed. Transmission electron microscopy, selected area electron diffraction, and X-ray diffraction studies indicate domain-like microstructure in a new experimental material, whereas a featureless amorphous gel-like microstructure exists in the conventional GIC. Nuclear magnetic resonance studies were also conducted. The new experimental GIC contains domains of (i) bonelike material (apatite), (ii) mesoporous material and (iii) other framework structures (aluminium phosphate in the high cristobalite structure), with its setting chemistry a restructuring of the aluminosilicate glass around the template of poly(acrylic acid). Conventional glass-ionomer cement may set by a similar but slower process. Leaching properties of glass-ionomer cements are also explained.
Assuntos
Ácido 2-Metil-4-clorofenoxiacético/metabolismo , Clofibrato/análogos & derivados , Ácido Clofíbrico/análogos & derivados , Ácido Clofíbrico/metabolismo , Glicina/análogos & derivados , Glicolatos/metabolismo , Ácido 2-Metil-4-clorofenoxiacético/análogos & derivados , Glicina/metabolismo , Conformação MolecularRESUMO
Black pigment, extracted from gallstones from patients, has been characterized as polybilirubinate. A similar material with the same physical properties was synthesized from bilirubin. The properties of black pigment are described. A mechanism for black pigment formation is postulated, and the possible relationship of this pigment to the formation of gallstones is discussed.
Assuntos
Bilirrubina/análogos & derivados , Colelitíase/metabolismo , Bilirrubina/análise , Microanálise por Sonda Eletrônica , Humanos , Espectrometria de Massas , Espectrofotometria InfravermelhoRESUMO
Scanning electron microscope studies on cholesterol gallstones, which had been subjected to, but had not been completely dissolved by, chenodeoxycholate and deoxycholate salts, have indicated the presence of an insoluble organic matrix, probably a mucopolysaccharide. Solution of a gallstone in vitro is enhanced by the addition of heparin which dissolved this matrix, thus allowing complete dissolution of cholesterol in a gallstone.
Assuntos
Ácido Quenodesoxicólico/uso terapêutico , Colelitíase/tratamento farmacológico , Colesterol , Ácido Desoxicólico/uso terapêutico , Heparina/uso terapêutico , Humanos , Técnicas In Vitro , Microscopia Eletrônica de VarreduraRESUMO
A number of sophisticated analytical methods are avialable in Australia and are in current use in medical research. Some basoc knowledge is required to understand the concepts behind their use, and expertise is necessary for interpretation of the results. In this brief review, the principles behind a number of modern analytical methods such as emission spectroscopy, electron microprobe, mass spectroscopy, infra-red spectroscopy, and X-ray diffraction, have been described in simple terms. These techniques may be used in the analysis of biological specimens. a number of illustrations of their use in medical research have been given.
