An association between the metabolic syndrome and reduced testosterone levels has been identified, and a specific inverse relationship between insulin and testosterone levels suggests that an important metabolic crosstalk exists between these two hormonal axes; however, the mechanisms by which insulin and androgens may be reciprocally regulated are not well described. Androgen-dependant gene pathways regulate the growth and maintenance of both normal and malignant prostate tissue, and androgen-deprivation therapy (ADT) in patients exploits this dependence when used to treat recurrent and metastatic prostate cancer resulting in tumour regression. A major systemic side effect of ADT includes induction of key features of the metabolic syndrome and the consistent feature of hyperinsulinaemia. Recent studies have specifically identified a correlation between elevated insulin and high-grade PCa and more rapid progression to castrate resistant disease. This paper examines the relationship between insulin and androgens in the context of prostate cancer progression. Prostate cancer patients present a promising cohort for the exploration of insulin stabilising agents as adjunct treatments for hormone deprivation or enhancers of chemosensitivity for treatment of advanced prostate cancer.

We describe a simple, convenient solid-phase radioimmunoassay of total thyroxine in unextracted serum. Serum samples are added directly to the assay incubation mixture, interference in the antigen/antibody reaction by the thyroxine-binding serum proteins being almost completely eliminated by the addition of 8-anilino-1-naphthalene sulfonic acid and incubation at pH 10.5. Residual interference is compensated for by including thyroxine-free serum in the standards. Use of thyroxine antibodies that are coupled to a solid support permits separation of free and antibody-bound hormone by a single washing step, followed by centrifugation. The method is specific, accurate, and reasonably precise. The results obtained compare well with those for radioimmunoassay of thyroxine in serum freed of protein by gel filtration, and with results of a competitive protein-binding method. The technical simplicity of the procedure should readily permit automation. These features suggest that the technique should be well suited for routine clinical laboratory use.

All proposed participants were asked to complete a detailed questionnaire describing their assay procedure and were asked to accept the following conditions: level of accuracy, within-and between-laboratory precision, and response times achieved. An attempt was also made at rudimentary quality control of the laboratories' interpretative performance.Because it was hoped that the Scheme might lead to necessary and practicable steps to improve performance, strict anonymity was precluded. An entirely open system in which the identities and performance of individual laboratories were known to all seemed equally undesirable and likely to inhibit participation. The balance between these two extremes was struck by adopting a 'confidential' mode of operation in which the identity of the laboratories is known only to the organisers of the Scheme. Biochemistry, 1979, 16, 131-146 Quality control of radioimmunoassays for proteins: Annals of ClinicalThe first two and a half years of a national scheme for serum growth hormone measurements SUMMARY The philosophy and achievements of the first two and a half years of a national quality control scheme for serum growth hormone assays are described. Three serum samples were distributed to participating laboratories every two weeks. A computer-produced summary of the quality control results, which contained scattergrams and a statistical analysis, was returned to participants four weeks after despatch. The performance of 11 experienced (SAS) laboratories was found to fulfil the necessary accuracy criteria, and their results provided the 'reference group mean', which served as the target value. Gross positive bias exhibited by several laboratories was due to the use of assays with inadequate sensitivity, and this practice was eliminated during the first six months. During the course of the Scheme the average bias fell from 30 to 14 %. With assays of adequate sensitivity, bias was almost invariably due to the misuse of standards. Median within-laboratory, between-batch precision (CV) improved from 23 to 15 %. The best performers achieved between-batch CV of 7% which was 1·5 x their within-batch CV: the worst had three-to four-fold differences between withinand between-batch CV. Rudimentary quality control of interpretation was found to result in improvements in interpretation per se and also served to reinforce the desire to improve numerical agreement.A 'recommended procedure' based upon supplied first and second antibody, and a communal 'reference range' from 280 untreated acromegalies, both proved valuable.

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