Biomedical subjects

G C Forrest

Publications and source records attributed to G C Forrest.

23 records · Page 2Linked to original sources

PubMed1978

Automated tests for the assessment of thyroid function.

Fully automated methods have been developed for the determination of thyroxine and triiodothyronine levels, antibodies to thyroglobulin and the assessment of thyroid hormone binding proteins in serum, using a continuous flow radioimmunoassay system. In addition the feasibility of a partially automated assay for thyrotrophin levels has been demonstrated. These employ Auto Analyzer modules and antibodies covalently linked to a magnetisable solid phase support. Separation of bound and free antigen is achieved by applying an external magnetic field. The system currently operates at a rate of 30 samples/h and requires only 10 minutes incubation since it is not necessary to reach equilibrium. The results are similar to those obtained by conventional manual techniques, however the precision is improved and operator error eliminated.

Female↗

PubMed1977

Development and application of a fully automated continuous flow radioimmunoassay system.

A fully automated, continuous flow radioimmunoassay system is described. The antibodies are covalently linked to a magnetic cellulose solid phase and separation of bound and free antigen is achieved by applying an external electromagnetic field. The bound fraction, after washing, is counted in a flow-through gamma counter chamber. The system employing Auto Analyzer modules, is highly reproducible and allows assays to be performed without equilibrium being reached, and only 10 minutes incubation time is required. The method is universally applicable to the assay of ligands, either protein, hormone, or drug, and for obtaining information about binding proteins. A new approach to the latter has been developed and is illustrated by a fully automated thyroid hormone uptake test which gives better discrimination between normal and pathological states than existing assays. The system operates at 30 samples/h and is characterised by the high precision, speed, and minimal carry-over which can be achieved.

Antigens↗

PubMed1977

Radioimmunoassay for digoxin with a fully automated continuous-flow system.

We describe a fully automated continuous-flow radioimmunoassay for digoxin with use of a Technicon AutoAnalyzer system. It makes use of antibodies linked to magnetizable particles; a magnet separates the bound and free fractions. The precise dispensing of reagents by the AutoAnalyzer system permits a small incubation volume (about 160 microliter) and the reproducible timing enables non-equilibrium conditions to be used. Thus a single sample is assayed in 15 min, with a sample throughput of 30/h. The standard curve ranges from 0.5 to 8.0 microgram/liter and is most precise between 1 and 3 microgram/liter, the between-assay coefficient of variation being less than 3%. There is no significant carryover between samples of high and low concentration, and results by the method correlate closely (r = 0.969) with those by an established manual assay in which charcoal separation is used.

Antibody Specificity↗

PubMed1976

Solid-phase, magnetic particle radioimmunoassay.

A solid-phase radioimmunoassay system has been developed based on the use of antibodies covalently linked to polymer-coated iron oxide (EnzacrylR). An electro-magnet is employed both to mix the particles during incubation (by switching the field on and off) and to separate the antibody-bound and free fractions. This obviates the need for vertical rotation and for the time-consuming, multiple centrifugations required with conventional solid phase procedures. The system is universally applicable and methods have been established for the assay of thyroxine, human placental lactogen and digoxin. The thyroxine assay was employed as a model and it was shown that the results obtained for serum samples correlated closely with those using a routine liquid-phase radioimmunoassay. The applicability of employing a second antibody linked to the iron oxide particles was also studied.

Binding Sites, Antibody↗

PubMedDate not supplied

A homogeneous electrode-based bioelectrochemical immunoassay for human chorionic gonadotrophin.

An amperometric, electrode-based technique for the quantification of human chorionic gonadotrophin (HCG) is described. Glucose oxidase and an anti-HCG monoclonal antibody are co-immobilised onto a glassy carbon electrode. The activity of the enzyme is measured electrochemically by use of an electron transfer mediator (dimethylaminomethyl ferrocene). Binding of HCG to the antibody modulates the activity of the immobilised glucose oxidase, permitting quantification of HCG. Sensitivity of the assay is 7 mIU HCG ml-1 in serum (First International Reference Preparation). Soaking in 50% ethylene glycol permits reuse of the electrode. Cross-reactivity of the electrode with other hormones has been examined.

Antibodies, Monoclonal↗