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Biomedical subjects

J Landon

Publications and source records attributed to J Landon.

195 records · Page 11Linked to original sources
PubMed1967

The preparation and immunological properties of I-labelled adrenocorticotrophin.

1. A procedure is described for preparing (131)I-labelled adrenocorticotrophin suitable for use in radioimmunoassay. 2. Adsorption of labelled and unlabelled adrenocorticotrophin at low concentrations occurs to various surfaces despite the presence of diluent protein. Adsorption and desorption errors are minimized by low pH and by the use of polystyrene vials. 3. Preparations with low initial damage are obtained if the radioiodination is performed rapidly and the separation of (131)I-labelled adrenocorticotrophin from unchanged [(131)I]iodide is carried out on cellulose columns by using dilute acid. 4. The immunological activity of (131)I-labelled alpha(1-24)-adrenocorticotrophin, but not of (131)I-labelled porcine adrenocorticotrophin, decreases with increasing specific radioactivity. The involvement of tyrosine residues in the immunological specificity of the alpha(1-24)-adrenocorticotrophin only is suggested to explain this finding.

Journal Article↗
PubMed1966

Assessment of hypothalamic pituitary function in endocrine disease.

The insulin test carried out with adequate safeguards under standardized conditions yields valuable information regarding hypothalamic and pituitary function when plasma levels of sugar, cortisol, and growth hormone are determined. The use of a test based on the plasma cortisol response to the infusion of lysine-vasopressin, a polypeptide with a corticotrophin-releasing action, is also of value as a test of pituitary function. Used in conjunction with the insulin test it enables pituitary disorders to be differentiated from those involving the hypothalamus.

Adolescent↗
PubMedDate not supplied

An audit of the processes involved in identifying and assessing bilingual learners suspected of being dyslexic: a Scottish study.

The Commission for Racial Equality (Special Educational Needs Assessment in Strathclyde: Report of a Formal Investigation, CRE, London, 1996) highlighted the significant under-representation of bilingual children among pupils assessed as having specific learning difficulties/dyslexia. In this present study an audit was undertaken in order to explore issues arising from the Commission's report, initially using 53 schools from one education authority. This revealed an extremely low incidence of suspected dyslexia among bilingual pupils. A second study was carried out in a further nine education authorities, surveying 91 schools with bilingual pupils. The incidence of suspected dyslexia in bilingual pupils was found to be extremely low. Twenty-seven cases were examined. Most cases concerned pupils aged 7:0-9:0. Difficulties associated with conventional indicators of dyslexia are discussed. A wide variety of assessment approaches were reported and the use of first language (L1) assessment varied. The process of assessment tended to be lengthy and inconclusive. However, this report suggests that caution is necessary when considering dyslexia in the early stages of second language (L2) development.

Adolescent↗
PubMedDate not supplied

The development of an enzyme immunometric assay for LH and the effects of the methods on the immunoreactivity of the conjugates.

Using an affinity purified sheep anti-human luteinizing hormone IgG-horseradish peroxidase conjugate (sheep anti-hLH IgG-HRP) and rabbit anti-human luteinizing hormone antiserum (rabbit anti-hLH) directed against different antigenic determinants, a solid-phase "sandwich" enzyme immunometric assay (EIMA) for human luteinizing hormone (hLH) was developed. The assay was validated and compared with a liquid phase "two site" immunoradiometric assay (IRMA) for hLH which uses same two antibodies. The sheep anti-hLH IgG, which had been affinity purified by eluting at pH 3.5 from a hLH-sepharose 4 B column, was labelled with 125I. The IRMA is based on simultaneous addition of two antibodies to standards and samples. After overnight incubation, separation was achieved by addition of Sheep anti-Rabbit Fc (SARFc) antiserum. In EIMA; partially denaturated (at pH 2.5) Sheep anti-Rabbit FcIgG (SARFcIgG) coated polystyrene tubes or microtitre plates were employed as solid-phase second antibody. The substrate was N,N'-o-phenylene diamine (2 mg/ml) and H2O2 (O.02%). Two methods, modified NaIO4 and 4-(N-maleimido methyl)-cyclohexane-1-carboxylic acid N-hydroxy succinimide ester (SMCC), were employed in the preparation of sheep anti-hLH IgG-HRP conjugate. The immunoreactivity and peroxidase activity of conjugate prepared with NaIO4 method was impared to various extends. Both EIMA and IRMA had good specificity, were not susceptible to interference from serum components and exhibited very low non-specific binding. The values determined by EIMA were independent of the serum volume employed. Standard added to serum samples was accurately determined and the results obtained from the analysis of serum samples correlated closely with those obtained by IRMA.

Horseradish Peroxidase↗