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Biomedical subjects

J A Fyffe

Publications and source records attributed to J A Fyffe.

At least 19 recordsLinked to original sources
PubMed1988

Diagnostic equipment outside the laboratory.

A questionnaire was circulated to clinical biochemistry laboratories in the North West Thames region of the United Kingdom requesting information on extralaboratory equipment. Data on the types and numbers of instruments in use, their relationship with the laboratory, and quality assurance procedures were obtained. Laboratories were prepared to maintain equipment over which they had no responsibility for purchase, training of users, or use. The quality assurance of these instruments gave even greater cause for concern. Although internal quality control procedures were performed on many of the instruments, laboratories were involved in only a minority of these procedures. Quality control procedures and training of users were undertaken on site in less than 50% of blood gas analysers and bilirubin meters and in less than 25% of glucose meters. External quality assessment procedures were non-existent for all of the instruments in use with the exception of glucose stick meters in two laboratories.

Bilirubin↗
PubMed1986

Regional quality assessment of pH and blood gas analysers.

The performance of 41 pH and blood gas analysers in 20 hospitals was assessed using commercially available blood gas ampoules provided by seven manufacturers. The stability of the material and the effect of ambient temperature on Po2 was assessed. The overall mean values were outside the manufacturers' assigned values on eight out of 64 values. Using IL413 analysers as a basis for comparison, significant differences were found for Pco2 on ABL1, Corning 168 and 178 analysers and for Po2 on ABL1 and 2 and Corning 178. No significant differences were found for pH. Poor performers were identified in terms of imprecision. Analysers within or associated with clinical biochemistry departments gave better performance than those outside the laboratory. The five analysers that provided insufficient data for inclusion in the study were all situated outside the laboratory. Analysers from different manufacturers performed equally well provided they were used regularly and in accordance with manufacturers' instructions.

Blood Gas Analysis↗
PubMed1981

Predictive value of derived calcium figures based on the measurement of ionised calcium.

The algorithms used in this hospital to assess calcium status are calculated ionised serum calcium and the serum calcium concentration adjusted for albumin. In order to establish their clinical usefulness, they were compared with the ionised calcium concentration measured on the Nova 2 instrument in patients with various calcium and protein abnormalities. Good correlation was found between the measured and calculated values. The predictive values for the calculated results and for total serum calcium concentrations are presented. In this series, the derived values were useful in predicting the serum ionised calcium concentration of the patients studied.

Blood Protein Disorders↗
PubMed1981

Preparation of material to control precision of calcium selective electrodes.

A simple procedure is described for the preparation of a stable precision quality control material for use in the measurement of level of ionised calcium in serum at or near the reference range. Repeat analyses on a Nova 2 ionised calcium analyser of serum pools stored at different temperatures over a period of three months showed coefficients of variation less of less than 4%.

Calcium↗
PubMed1981

Effects of trimethoprim and sulphonamide preparations on the pituitary-thyroid axis of rodents.

The effects on pituitary-thyroid function of the commonly prescribed anti-bacterial preparations co-trimoxazole and co-trifamole, and their component drugs, have been studied in the rat and compared to the changes caused by propylthiouracil. Co-trimoxazole and co-trifamole, in doses 20-fold in excess of a pharmacological dose administered for 10 days, produced marked changes in hormone levels consistent with blocking of hyperplastic goitre formation, were also demonstrated. Propylthiouracil produced less marked changes of thyroid hormone levels but higher levels of thyroid-stimulating hormone. Pharmacological doses of co-trimoxazole and co-trifamole and sulphamoxole, the sulphonamide component of co-trifamole, caused significant changes in thyroid hormone levels consistent with anti-thyroidal activity. In contrast, there was no evidence that trimethoprim, which is common to both preparations, or sulphamethoxazole, the sulphonamide component of co-trimoxazole, had an anti-thyroidal action, indeed, serum thyroxine levels were significantly increased at pharmacological dosage. We have concluded that the new commonly prescribed combination preparations retain the goitrogenic properties of the earlier sulphonamides.

Animals↗
PubMed1980

The prolactin response to metoclopramide in growth hormone deficient adolescent males.

The growth hormone (GH) and prolactin (PRL) responses following administration of 10 mg i.v. metoclopramide (MCP) ('Maxolon'--Beecham Pharmaceuticals) have been examined in thirty adolescent males with short stature and delayed puberty, either of whom have isolated growth hormone deficiency. The results demonstrate that peak GH and PRL levels following stimulation were highly significantly correlated when all subjects were analysed together (r = 0.61, P < 0.001) but when the responses of the GH deficient and non-deficient groups of subjects were analysed separately no significant correlation was obtained (P > 0.1), this reflected the fact that the PRL response to MCP was significantly lower in the GH deficient group (P < 0.0002). In addition two boys who demonstrated biochemical GH deficiency prior to puberty only, showed PRL responses similar to boys with normal GH reserves. The results suggest that the PRL response to MCP may be of value in the assessment of stimulation tests of GH reserve, as well as in the selection of patients for treatment with GH.

Adolescent↗
PubMed1980

Clinical and laboratory evaluation of four methods of assessing free thyroxine status in thyroid clinic patients.

The clinical value of four laboratory methods of assessing free thyroxine status was compared in 82 consecutive patients newly referred to a thyroid clinic with suspected thyroid dysfunction. The methods of determining free thyroxine used were: (1) free thyroxine index using a thyroid hormone uptake test (FTI (THUT)); (2) a free thyroxine index using thyroxine binding globulin (FTI (TBG)); (3) a kinetic radioimmunoassay (Immophase); and (4) an equilibrium dialysis method. The definitive thyroid status was evaluated by a combination of clinical assessment (including Wayne index), routine tests of thyroid function (total T4, T3, TSH, and TRH tests where appropriate), and by therapeutic trial in one case. The diagnostic efficiency of the tests was markedly dependent upon the method of determining the reference range for euthyroid patients. Best efficiency for each test was achieved using an amended range after excluding outliners. Test efficiency was then 97.6% for FTI (THUT) and the kinetic RIA and 96.8% for FTI (TBG). Misclassification by one or more of these tests occurred in only four patients (mild hypothyroid, euthyroid on phenytoin, euthyroid on oral contraceptive and valium, T3 hyperthyroid). In contrast, free T4 by equilibrium dialysis was much less efficient (86.6%) and was technically the most complex. Overall the kinetic T4 RIA provided similar diagnostic information to the indirect indices. However, further studies of cost benefit in settings other than a thyroid clinic are required to assess whether this method might replace total T4 and/or FTI as a first-line test of thyroid function.

Adult↗
PubMed1980

Somatomedins and other serum growth factors: a review of current concepts.

Growth hormone is essential for sustaining longitudinal growth in man. However, during the last 20 years, it has become evident that the actions of growth hormone, at a cellular level, are mediated by specific growth promoting factors. This paper describes the nature and actions of mammalian growth factors and summarises the immense contribution that the measurement of these substances has made towards the elucidation of many problems in the science of human growth and development.

Cyclic AMP↗
PubMed1979

Familial pseudohyperkalaemia. A new syndrome.

Inherited pseudohyperkalaemia due to an abnormal red-blood-cell potassium leak was discovered in 16 of 28 relatives of a woman with pseudohyperkalaemia. Autosomal dominance seemed to account for inheritance of this abnormality. Affected subjects were not anaemic and had normal in-vivo plasma-potassium concentrations.

Adult↗
PubMed1978

Response to thyrotrophin releasing hormone in Klinefelter's syndrome.

In eleven patients with Klinefelter's Syndrome TSH, T4 and T3 levels have been measured after stimulation with TRH. The eleven patients included three who had been noted to have a low radioactive iodine uptake and two of these also had abnormally low T4 levels. Three of the patients were receiving androgen replacement therapy. A normal response to TRH was observed in all cases.

Adult↗
PubMed1978

Hypothalmic-pituitary adrenal responsiveness to dexamethasone-insulin tolerance test in acromegalic patients before and during treatment with bromocriptine.

Insulin tolerance tests were carried out in 10 acromegalic patients after 1 mg dexamethasone had been given the previous evening (DEX-ITT). Nine patients showed a rise in plasma 11-OHCS and four patients showed a rise in plasma growth hormone (GH) levels. These responses were unaltered after treatment with bromocriptine 10 mg daily for two months. Basal plasma GH levels fell in 6 of the patients and the mean plasma GH levels of the 10 patients during an oral glucose tolerance test (OGTT) fell from 63.2 +/- 25.5 ng/ml before treatment to 53.0 +/- 27.1 ng/ml (mean +/- sem; p less than 0.05). These data fail to confirm a previous report of abnormal hypothalmic-pituitary-adrenal suppressibility during a DEX-ITT in acromegalic patients. They also indicate that bromcriptine does not alter the responses of plasma 11-OHCS and plasma GH to the DEX-ITT despite lowering plasma GH levels.

11-Hydroxycorticosteroids↗
PubMed1977

Thyroxine and triiodothyronine levels in hyperthyroid patients during treatment with propranolol.

Serum triiodothyronine (T3) and thyroxine (T4) levels were measured in twelve hyperthyroid patients before and after treatment with propranolol, 40 mg four times daily, for 2 weeks. There was a significant fall in serum T3 and a significant rise in serum T4 concentrations in the group as a whole and it was concluded that the clinical effectiveness of propranolol in hyperthyroidism may be mediated in part by its action on the peripheral metabolism of thyroid hormones. Propranolol treatment should be withdrawn gradually as removal of the suppressive action of the drug on thyroid hormone metabolism is potentially hazardous, particularly in patients with ischaemic heart disease.

Adult↗