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Biomedical subjects

G Desmet

Publications and source records attributed to G Desmet.

At least 55 records · Page 3Linked to original sources
PubMed1985

[Biosensor development in clinical analysis].

The use of enzymes immobilized or as markers formed the subject of more than thousand publications in the field of industry or biomedical applications, during the last five years. Recently, some authors published works concerning immobilization of total microorganisms for catalytic purposes, others use the enzymatic activity for marking molecules involved in immunological analysis processes. Together industrial biotechnology and medical analysis laboratory are interested with the evolution of these procedures involving the activity of immobilized enzymes. Enzyme immobilization allowed the lowering of analysis costs for, in this case, the enzyme can be used several times. We take account of the two main cases which are encountered during utilization of immobilized enzymes of analytical purposes. The enzyme is used directly for the catalysed reaction or it is used as enzymatic marker. These both aspects are developed mainly for the elaboration of enzymatic and immunoenzymatic electrodes and the realization of automatic computerized devices allowing continuous estimation of numerous biological blood parameters. From these two precise examples, glucose and antigen determination, the authors show the evolution of these technologies in the field of immobilized enzymes or captors and the analysis of signals given by these electrodes requiring a computerized treatment. This new technology opens to important potentialities in the analytical field. The automatization of these devices allowing the control in real time, will probably make easier the optimization steps of procedures actually used in the biomedical sphere.

Acetylcholine↗
PubMed1981

Use of solid phase biochemistry for potentiometric enzyme immunoassay of oestradiol-17 beta - preliminary report.

The present report gives preliminary results of a new sensitive method for potentiometric determination of oestradiol-17 beta in solution, as an application of the competitive enzyme-linked immunoassay technique. Anti-oestradiol-17 beta antibodies are immobilized on a pig skin gelatin membrane, which is incubated with peroxidase-labelled steroid and oestradiol. After fixation of the membrane onto the sensor of an iodide sensitive electrode, the enzymatic activity was evaluated in the presence of hydrogen peroxide and iodides, the electrode potential being a function of hapten concentration in the solution. The purpose of this preliminary work was to determine the optimized conditions for specificity and sensitivity of the antibody-coated membrane in the presence of peroxidase-labelled oestradiol and oestradiol, and to eliminate possible interferences due to adsorption or ionic fixation of enzyme-labelled steroid. The first tests carried out with oestradiol standard solutions gave satisfactory results at levels ranging from 57 pmol/l to 9.2 nmol/l, suggesting that this new procedure should find application in the determination of oestradiol-17 beta in biological fluids.

Body Fluids↗
PubMed1979

An "antibody electrode," preliminary report on a new approach in enzyme immunoassay.

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.

Animals↗
PubMed1979

[Determination of alphaxalone in serum and urine by gas-liquid chromatography. Application in anaesthesiological pharmacology (author's transl)].

The authors propose a simple and reliable method for determination of alphaxalone [3 alpha-hydroxy(5 alpha)pregnane 11,20 dione] in serum and urine, during long-duration anaesthesia using Althesin, mixture of alphaxalone and alphadolone acetate [21 acetoxy, 3 alpha-hydroxy(5 alpha)pregnane 11,20 dione]. If assays of alphadolone appear difficult and without any precision, because of numerous interferences, the determination of alphaxalone in serum and urine seems interesting for pharmacokinetic and metabolic investigation. We confirm the quick rate of disappearance of alphaxalone from blood, associated with a very active metabolism in the liver. The results show that it exists a relation between the concentration of alphaxalone in blood and the value of anaesthesia judged on clinical and electrical criteria. We cannot however conclude that Althesin presents a cumulative effect, because we used important amounts of anaesthetic agent.

Alfaxalone Alfadolone Mixture↗
PubMed1978

[Potentiometric determination of hepatitis B surface antigen in biological fluids (author's transl)].

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.

Antibodies↗
PubMed1977

Use of magnesium silicate before gas-liquid chromatography for determination of "total estrogens" in urine during pregnancy.

The authors propose a simple, rapid, reproducible and reliable method for determination of "total estrogens" in urine during the last three months of pregnancy. The procedure consists of separation of free urinary estrogens, obtained after rapid hydrolysis, on a column of magnesium silicate. The estrogens are adsorbed on the column at acid pH and eluted by 1 M potassium hydroxide. Following extraction of the eluate by diethyl ether and formation of trimethylsilyl ether derivatives, the steroids are analysed by gas-liquid chromatography. This new procedure is used routinely in our laboratory, one assay being carried out in less than three hours. The results appear to be comparable to those obtained with classic methods. We wish to report the elimaination curves of "total estrogens" during normal pregnancies and their allowable limits.

Chromatography, Gas↗
PubMed1977

[A simple method for the separation and purification of the surface antigen of hepatitis B from serum (author's transl)].

The present report describes a simple, rapid and reproducible procedure for preparation of hepatitis B surface antigen from human positive sera, with a satisfactory yield. After removal of beta- and alpha-lipoproteins by dextran sulphate precipitation and subsequent removal of IgM and a part of the other serum proteins by dialysis against distilled water, the supernatant obtained presents almost no change in its surface antigen content. After passing this solution through a molecular sieve of Biogel A-5 m, the surface antigen is detected in a well-defined peak. The fraction correspinding to this peak is collected in its totality. After lyophilization, it is passed through a molecular sieve of CPG 10, in phosphate buffer; this allows recovery of a substance which has retained its structural as well as its antigenic properties, and which is intact and practically free of any serum contamination.

Blood Protein Electrophoresis↗
PubMed1976

Anti-hypertensive effect of acebutolol: its relation to sympathetic nervous system responsiveness and to plasma renin and dopamine-beta-hydroxylase activities.

1. Acebutolol, a beta1-receptor blocker, has, at a daily dose of 800 mg, a mild but significant anti-hypertensive effect in moderate sustained essential hypertension with normal or low plasma renin activity. 2. Prediction of its anti-hypertensive effect is better based on the evaluation of the sympathetic nervous system responsiveness to head-up tilt than on the evaluation of plasma renin activity or dopamine-beta-hydroxylase. 3. The anti-hypertensive effect of acebutolol is better explained on the basis of inhibition of the sympathetic nervous system activity than on the basis of suppression of plasma renin activity. 4. A positive correlation between plasma renin activity and dopamine-beta-hydroxylase in patients on diuretics suggests the common dependence of these two variables on sympathetic overactivity.

Acebutolol↗
PubMed1976

[CT 1341 in continuous administration in 75 cases of prolonged general anesthesia in odontostomatology (constant flow assured by a double-lumen venous catheter and electric perfuser)].

The authors used during 75 prolonged general anaesthesia in maxillo-facial surgery CT. 1341 (Alfatesine) administered pure at constant flow rate through a double lumen venous cannula and electric perfuser. Four series of patients were thus distinguished depending on their use or not of N2O as the only analgesic and of gallamine. We do not agree with the classical assertion that CT. 1341 has a cumulative effect on some EEG results. The technique is quite inocuous and the authors propose a technique using CT. 1341 at a dose of 0.1 ml/kg for induction of anaesthesia with, later, 1 mg/kg of gallamine. Under a mixture of oxygen and nitrous oxide at 60 p. 100, the maintenance dose advised in 6.17 microliters per kilo, per minute of CT. 1341.

Adult↗