PubMed Health⌕ Search

Biomedical subjects

P G Byfield

Publications and source records attributed to P G Byfield.

15 recordsLinked to original sources
PubMed1991

Heterogeneity of circulating TSH-receptor antibodies in thyroid disease demonstrated directly by chromatography.

The heterogeneity of circulating TSH-receptor antibodies (TRAb) has been demonstrated directly by affinity chromatography on the dye Remazol Yellow-GGL. The technique resolved these antibodies into discrete peaks within the general serum immunoglobulin background. Peaks were detected initially by a binding (radioreceptor) assay and then characterized by their ability to stimulate the uptake of iodine-125 into FRTL-5 cells. Thirteen subjects with high serum levels of TRAb were studied. The two hypothyroid patients each produced a single peak of TRAb activity with no ability to stimulate uptake of iodine-125 into cultured cells. The remaining 11 patients had Graves' disease; their sera produced a range of elution profiles after chromatography with TRAb activity resolved into as many as five peaks. Considerable differences were seen in the relative abilities of the resolved TRAb components to bind to receptors and to stimulate cellular uptake of iodine-125 both between and within individual samples. No two patients produced components which chromatographed in the same position on the gradients employed for elution from the dye.

Antibodies, Heterophile↗
PubMed1990

IgG heavy-chain subclass restriction of thyrotropin-binding inhibitory immunoglobulins in Graves' disease.

The IgG subclass composition of antibodies is an important determinant of their function. Thyrotropin receptor antibodies cause the hyperthyroidism of Graves' disease but their subclass distribution has been incompletely investigated. We have therefore purified IgG subclasses from Graves' sera by passage over affinity columns designed to deplete all but a single subclass, and then assayed those pure subclass fractions for their ability to displace radiolabelled thyrotropin from its solubilized receptor as a measure of thyrotropin receptor antibody activity. Sufficient activity was recovered for analysis in nine of 10 Graves' patients, in five of whom activity was almost completely (97-100%) restricted to the IgG1 subclass; in the remaining four patients the response was predominantly IgG1 and IgG4 with marked under-representation of the IgG2 subclass. This contrasts with the unrestricted subclass response, in the same fractions, for autoantibodies against thyroglobulin and microsomes. These results suggest that there may be a primary defect at the B-cell level in Graves' disease.

Autoantibodies↗
PubMed1979

Different measurements of thyroid function in hypothyroid infants diagnosed by screening.

Different measurements of thyroid function including I123 thyroid scanning were performed in 16 hypothyroid infants diagnosed by a TSH screening project. These results were then related to the clinical presentation and the bone age. Although T3 levels were preferentially maintained, it was the best single measure of the severity of hypothyroidism. Thyroglobulin may have a role in the diagnosis of athyrosis. Scanning showed that athyrosis was uncommon (12.5%) but an ectopic gland occurred in 40%, and accounts for many of the less severly affected cases found on screening. Some of these measurements may have prognostic significance.

Female↗
PubMed1979

Interrelation of the pituitary-thyroid system at birth in man.

Samples of cord blood derived from 105 normal babies after uncomplicated deliveries were assayed for thyroxine (T4), tri-iodothyronine (T3), reverse tri-iodothyronine (rT3), thyroxine-binding globulin (TBG) and thyrotrophin (TSH). The values for T3, rT3 and TSH were log-normally distributed (geometric means 0.62 nmol/l, 3.28 nmol/l and 10.9 mu./l respectively) and those for T4 and TBG were normally distributed (means 126 nmol/l and 13.7 mg/l), The data were systematically analysed and no evidence was obtained to suggest that the concentration of TSH, which varied widely, was regulated by any of the thyroid hormones alone or in combination. There was a direct relation between the concentrations of T4 and T3 in the cord blood at birth but not between either of these and rT3. There is thus no evidence of a functional interdependence of the hypothalamic-pituitary-thyroid system in man at birth.

Fetal Blood↗
PubMed1978

Radioaffinity assay, a new approach to binding assays applied to the measurement of serum albumin.

The affinity adsorbent Cibacron Blue F3GA-Sepharose 4-B has been used to develop a binding assay for human serum albumin. The method is simple, accurate and precise. It agrees well with the 'rocket' immunoelectrophoretic method and is proposed as an alternative technique for the re-estimation of albumin levels in the low range (less than 30 g/l) where the bromocresol green dye-binding method overestimates. Bilirubin, several drugs, gammaglobulin, haemoglobin and heparin do not interfere with the estimations.

Bromcresol Green↗
PubMed1978

Reverse triiodothyronine, thyroid hormone, and thyrotrophin concentrations in placental cord blood.

Reverse triiodothyronine (rT3), triiodothyronine (T3), thyroxine (T4), thyroxine binding globulin (TBG), and thyrotrophin (TSH) were measured in sera from placental cord blood in an unselected series of 272 deliveries. In this series the concentrations of rT3 (mean 3.33 nmol/l, 95% confidence limits 1.6--7.0 nmol/l), were log normally distributed and did not overlap the adult normal range (0.11--0.44 nmol/l). There were no correlations between the cord blood concentrations of rT3, T3, T4, and TSH. The cord serum rT3 concentration was not influenced by maturity, birth-weight, or neonatal risk factors, whereas these factors did affect the concentrations of T3, T4, AND TBG. There is no arteriovenous rT3 concentration difference across the placenta, therefore the cord rT3 reflects the systemic rT3 concentration in the baby at birth. As rT3 in the neonate largely, if not entirely, derives from thyroxine from the fetal thyroid, measurement of the cord rT3 concentration may be a good immediate screening test for neonatal hypothyroidism.

Fetal Blood↗
PubMed1976

An active site peptide from human placental alkaline phosphatase.

A preparation of human placental alkaline phosphatase was labelled covalently at the active site with [32P]orthophosphate. Treatment with trypsin gave essentially one radioactive peptide, the active site peptide, of approximately 2300 molecular weight. Dansylation of the peptide showed that the amino-terminal residue was glycine. After acid hydrolysis the only radioactively-labelled amino acid present was serine phosphate. The amino acid composition was similar to those compositions reported for active site peptides from other alkaline phosphatases.

Alkaline Phosphatase↗
PubMed1975

Separation of phenylthiohydantoin-amino acids by high-pressure liquid chromatography.

A method for the separation of all phenylthiohydantoin (PTH)-amino acids except PTH-arginine and PTH-histidine by high-pressure liquid chromatography on a silica column is described. Elution is performed with a concave solvent gradient from hexane-methanol-propanol (3980:9:11) to methanol-propanol (9:11). A complete run is achieved in 40 min with a pressure drop of 1000 p.s.i. over the 250 mm X 2.1 mm column. Eluted peaks of 2-5 nmole are easily detected by their ultraviolet absorption at 254 nm. This method is superior to existing gas-liquid and thin-layer chromatographic techniques since all PTH-amino acids except PTH-arginine and PTH-histidine may be both separated and quantitated in a single run of 40 min. The use of the technique in conjunction with an automated peptide sequence analyser is illustrated.

Adrenocorticotropic Hormone↗