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Biomedical subjects

W H Walker

Publications and source records attributed to W H Walker.

At least 55 records · Page 3Linked to original sources
PubMed1980

Beta-thromboglobulin radioimmunoassay. A laboratory characterization and evaluation.

Platelets release beta-thromboglobulin from alpha-granules when they are activated by various stimuli. An evaluation and optimization of a radioimmunoassay for beta-thromboglobulin is described. The optimum conditions for the reaction have been characterized, and the use of second antibody and polyethylene glycol allows completion of the assay within 24 hours. Similar BTG concentrations were obtained using a 1-hour non-equilibration assay but the 1-hour assay was inefficient for processing large volumes of specimens and has the potential for cross reactivity. BTG standards were unstable but the shelf-life was prolonged with aprotinin or by storage at -70 degrees C. Plasma BTG concentration in 80 normal individuals was 28 +/- 18 ng/ml. (mean +/- 2 S.D.).

Adult↗
PubMed1980

Influence of tissue homogenization techniques on levels of estrogen and progesterone receptors measured in calf uterus and human breast tumors.

We have investigated the solubilization of estrogen and progesterone receptors during homogenization of human breast tumor and calf uterus tissue. With chopped human breast tumor tissue, the maximum yield of binding proteins occurred after mechanical homogenization at 4 degrees C with a polytron PT-10 instrument running at setting 5 for 10-15 seconds. With frozen or lyophilised tissue powders the maximum yield of binding proteins occurred after intermittent vortex mixing with buffer over 60 min. at 4 degrees C. The solubilized receptor proteins were stable for at least 150 min. at 4 degrees C. Mechanical homogenization of the tissue powder suspensions resulted in rapid denaturation of the receptors. No improvement in stability was obtained by including 10 mM monothioglycerol and 10% glycerol in the homogenization buffer.

Animals↗
PubMed1980

Solid-phase radioimmunoassay with protein-A-bearing Staphylococcus aureus cells used to assay a protein (ferritin) and a hapten (digoxin).

We compared use of protein-A-containing Staphylococcus aureus bacteria with conventional ammonium sulfate precipitation and second-antibody methods of separating bound and free antigen in the radioimmunoassay of a hapten (digoxin) and protein (ferritin) in human sera. In each case, values obtained with the heat-killed, formalin-fixed bacteria correlated well with those found by established methods. No matrix effects were detected in either hapten or protein measurements. Because of the affinity of S. aureus for rabbit IgG, rabbit antisera could be used with a small number of bacteria to detect antigen in the presence of 50-fold excess human IgG. The availability of S. aureus and ease of handling make this reagent a rapid, economical alternative of general applicability in radioimmunoassay.

Digoxin↗
PubMed1977

A radioimmunoassay for serum ferritin.

We describe the development and evaluation of a serum ferritin radioimmunoassay, in which 125l-labeled ferritin and rabbit anti-ferritin antibody are used. Goat anti-rabbit gamma-globulin antibody, together with polyethylene glycol, is used as the separating reagent. The assay has a working range up to 500 mug of ferritin per litre, and a sample requirement of 75 mul of serum for assay at two dilutions. The assay requires 24 h. it has a sensitivity of 1.5 mug of ferritin per litre and a long-term precision (CV) of 13%. Reference intervals for a population of men were 18-330 mug/litre, with no marked age dependence, while those for a population of women older than 50 years were 18-200 mug/litre. Many apparently healthy women in the 20-50 year age group have much lower concentrations. Serum ferritin concentrations of less than 18 mug/litre are indicative of iron deficiency, defined as the absence of stainable iron in an aspirate of bone marrow.

Adult↗
PubMed1976

Thermodynamic aspects of some radioassays.

In a number of radioimmunoassays and radiotransin assays, effective equilibrium constants have been measured at different temperatures in order to define the relative contribution of changes of entropy and enthalpy to the change in free binding energy. In systems with a large enthalpy component, the lowest possible incubation temperature maximizes sensitivity, and control of temperature throughout the assay is important. Conversely, when enthalpy change is small, a high temperature allows rapid attainment of equilibrium without loss of sensitivity. At a theoretical level, the thermodynamic characteristics of binding may allow some insight into the nature of the binding process.

Angiotensin II↗
PubMed1975

A rapid radioimmunoassay method for plasma luteinizing hormone.

1. A rapid double antibody radioummunoassay method for the determination of plasma luteinizing hormone (hLH) is described. 2. The method involves preincubation of the anti-LH serum with the precipitating second antibody and incubation of this mixture with unknows and standards at room temperature overnight. The incubation tubes are then centrifuged, supernatants decanted and the precipitates counted. 3. A total of two working days is required to complete the assay and report the results. 4. This method is more rapid than the conventional ones currently used for the estimation of LH in blood.

Animals↗
PubMed1975

Rapid, specific assay for plasma cortisol by competitive protein binding.

We describe a modified competitive protein-binding method for assay of plasma cortisol. Plasma samples are deproteinized by dilution with an ethanol/phosphate buffer, followed by heating at 100 degrees C for 2 min. Horse serum is used as the source of transcortin. Free radioactivity is separated from the protein-bound component by partition into liquid scintillation counting within 60 min. The assay has better specificity and precision than a competitive protein-binding assay in which ethanol extraction and Florisil adsorbent are used, and results correlate well with those of a specific radioimmunoassay method.

Binding, Competitive↗