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Biomedical subjects

G Grenner

Publications and source records attributed to G Grenner.

6 recordsLinked to original sources
PubMed1990

Dry chemistry thin film immunoassay.

The authors report the development of a novel thin film multilayer immunoassay technology. The technology is applied to therapeutic drug monitoring and thyroid hormone testing in serum or plasma and can be extended to assays of other low molecular weight analytes. The assay detection range spans five orders of magnitude, from 1 x 10(-3) to 1 x 10(-8) M. The assay element comprises of multilayer coated chip, containing the active reagents in an agarose matrix and a plastic module serving both as a holder and a spreader. The assays are in the fluorescent competitive immunoassay format of the ligand displacement mode and are performed on an automated instrument with random access capability. The assays are fast and reliable and gave very good agreement when compared to reference methods.

Immunoassay↗
PubMed1989

Multilayer fluorescent immunoassay technique.

We describe a new multilayer immunoassay element for the determination of haptens in undiluted serum and plasma. Polysaccharide layers are coated onto a plastic base. The signal layer contains an immobilized antibody and a fluorescent-labeled hapten. A second layer, containing a pigment, acts as an optical screen. Sample spreading is achieved by a molded grid in contact with the upper layer of the immunoassay element. After sample is added to the element, endogenous analyte competes with the labeled hapten for the binding sites of the immobilized antibody; equilibrium is reached in 4-12 min. Because of the relative liquid-holding capacities of the layers and the grid, only a small amount of the free components remains in the signal layer. The signal is measured by front-surface fluorimetry. This technology has been applied to theophylline and thyroxin assays. Within- and between-run CVs range from 3% to 6%. Comparisons with fluorescent polarization immunoassays (Abbott TDx) showed excellent correlation (theophylline: r = 0.98, slope = 1.07, intercept = 0.3; thyroxin: r = 0.97, slope = 0.91, intercept = 0.8). The new method requires only one pipetting step (sample delivery) and is potentially applicable to a wide range of analytes.

Fluorescence Polarization↗
PubMed1976

Coenzyme properties of NAD+ bound to different matrices through the amino group in the 6-position.

A method for the synthesis of N6-(2-aminoethyl)-NAD+ is given. The binding of this NAD+ derivative to different soluble and insoluble supports and the direct coupling of NAD+ to epoxyactivated Sepharose are described. Proofs are given that NAD+ is bound through the amino group in 6- position and the NAD+ derivative through the aliphatic amino group of the side chain. Non-enzymic reduction of the bound coenzyme to an almost quantitative extent is possible in all cases, but the enzymic reduction is largely influenced by the support. While N6-(2-aminoethyl)-NAD+ coupled to soluble dextran is nearly completely reducible by different dehydrogenases with a velocity of about 40% of that for free NAD+, the coenzyme bound to different insoluble matrices is very slowly reduced. Only 5% of the coenzyme derivative bound to BrCN-activated Sepharose are reducible, but 40% when it is bound through a spacer. From capacity determinations evidence is given that, even in this coenzyme gel, only those coenzyme molecules are useful in affinity chromatography which are on the surface of the gel grains; it is supposed that this may be due to the slow diffusion of an enzyme into the inner parts of an affinity gel.

Binding Sites↗
PubMed1976

Microcalorimetric methods for substrate determination in flow systems with immobilized enzymes.

The enthalpy of processes catalyzed by immobilized enzymes in the reaction cell of a LKB-flow calorimeter is used for determination of urea (0.5-5 mumol) and glucose (0.03-0.5 mumol). Accuracy is 2-5% and the time needed for one analysis is 20 min. A sensitive "enzyme thermistor" consisting of a flow through cell with an immobilized enzyme and two thermistors is described, which permits glucose determinations (0.05-1 mumol +/- 0.03 mumol) by means of temperature difference caused by reaction heat. Coupling of enzyme reactions for increasing reaction heat and consequently sensitivity in calorimetric determinations is demonstrated.

Binding Sites↗
PubMed1976

[Coenzym properties of some Ade-1- and Ade-N6-substituted NAD derivatives (author's transl)].

By reaction of NAD with different oxiranes or with aziridine, derivatives of the coenzyme are obtained with substituents in position 1 or on the amino group in position 6 of the adenine ring. While the Ade-1-substituted derivatives show high Km values with different dehydrogenases and are reduced only very slowly by these enzymes, the coenzyme derivatives substituted at the amino group behave very similarly to NAD. Correlations were found between coenzyme efficiency of the compounds and the lipophilic character of their substituents. The results can be interpreted from the structure of the active site of the dehydrogenases investigated.

Coenzymes↗