Biomedical subjects
Publications and source records attributed to D Thomas.
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Physicians are mostly interested in medical text processing if they can directly interrogate the exact content of each text and not only keys leading to a more or less rough retrieval. Remede is a prototype of a medical documentary language using current medical terms and few syntactic rules. It allows to make reports directly processeable by computers. The paper presents the system runninr for one year in the Service of Cardiology-La Salpêtrière Hospital Paris.
Measurements of glucose in samples exhibiting high variability in oxygen content present an important problem to solve for pO2 detection methods. Different solutions exist, all based on the stabilization of the pO2 sample before or during the measurement. The electrode described in this paper itself contains enough O2 to compensate for the variability of the sample oxygen content. The enzyme is cross-linked with gelatin using the bifunctional agent, glutaraldehyde. Amperometric enzyme electrodes have been constructed using these membranes. Measurements have been done by collecting the derivative in time of the signal given by the electrode for blood or plasma samples.
Hysteresis, oscillations, and pattern formation in realistic biochemical systems governed by P.D.E.s are considered from both numerical and mathematical points of view. Analysis of multiple steady states in the case of hysteresis, and bifurcation theory in the cases of oscillations and pattern formation, account for the observed numerical results. The possibility to realize these systems experimentally is their main interest, thus bringing further arguments in favor of theories explaining basic biological phenomena by diffusion and reaction.
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A case of systemic lupus erythematosus (SLE) is reported in which chorea was the dominant clinical feature, and which presented following a spontaneous mid-trimester abortion. The diagnosis, natural history and management of this uncommon manifestation of CNS lupus is discussed, as well as the influence of pregnancy on disease activity in SLE.
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We report preliminary experiments on a new, sensitive, and reliable procedure for enzyme immunoassay of various antigens in biological fluids. The method, developed from the biological model "hepatitis B surface-antigen/antibodies," is less time consuming than most immunochemical techniques and eliminates many inconveniences arising from use of isotopes. We use a solid-phase "sandwich" procedure, the antibodies being immobilized on gelatin membranes, and determine antigen concentration with the help of an iodide-sensitive electrode modified by fixing the active membrane onto the crystal sensor. We have established the analytical criteria of the method and compared it with the solid-phase radioimmunoassay for the surface antigen in dilution series. One-tenth microgram of antigen per liter can be reproducibly detected with our method. Use of antibody electrode should easily be extended to assay of other antigens and haptens that usually are determined by radioimmunoassay.
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Two cases are reported of right medioventricular subinfundibular stenosis with intact intraventricular septum. This rare congenital malformation, also known as "double chambered right ventricle", and usually associated with an intraventricular communication, can only be diagnosed with certainly on the results of hemodynamic and angiographic studies which demonstrate the abnormal medioventricular muscle bands. A steep intraventricular pressure gradient was noted in the first patient who was operated upon successfully. The second patient developed progressively increasing stenosis which underlines the need for long-term observation of cases in which there is little initial obstruction. Particular types of electrocardiographic recordings, not previously reported, were present in both cases; in one there was an unexplained long QT interval; in the other a first degree nodal atrioventricular block with atrial arrhythmia, requiring the implantation of a cardiac stimulator.
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A case of a patient with Crohn's disease who was treated with azathioprine, and developed intestinal Hodgkin's disease as a complication is described.
A new enzyme electrode is described to measure continuously acetylcholine concentration. A coating containing active acetylcholinesterase is produced on a pH-glass electrode. The mean thickness of the coating is 50 micrometer. Optimal operational conditions with respect to buffer concentration, ionic strength, linearity, stability, sensitivity, pH of the bulk solution, and response time are studied and discussed. The use of acetylcholinesterase-containing membranes as sensors could offer several novel advantages.
A functional NAD molecule was immobilized at the active site of Alcohol dehydrogenase within a proteic membrane. The presence and the functionality of the cofactor was checked by fluorescence analysis. The dehydrogenase NAD membrane does not require addition of soluble cofactor for its activity. The system represents a new worthwhile approach because both problems of retention and regeneration of cofactor are solved. The method can be used not only for industrial and analytical applications but also to try to get a better understanding of the kinetics and mechanisms of the catalytic action of dehydrogenase.
The present report describes a sensitive and reliable method for potentiometric determination of hepatitis B surface antigen in biological fluids, as an application of enzyme-linked immunoassay technique by a "sandwich" procedure. Specific antibodies are immobilized on a gelatine membrane which covers the sensor of an iodide-sensitive electrode. After immersion of the modified electrode in a dilute solution of antigen, the enzymatic activity is evaluated in a solution of peroxidase-labelled antibodies, in the presence of substrate and iodides. The electrode potential is a function of antigen concentration in the solution. This new procedure should find its application in the determination of substances present in very low concentration in biological fluids.