Biomedical subjects
S Shalet
Publications and source records attributed to S Shalet.
Advantages of IRMA over RIA in the measurement of ACTH.
A technically simple and rapid two-site immunoradiometric assay (IRMA) for human ACTH, based on monoclonal antibodies (MAbs), was compared with a clinically validated ACTH radioimmunoassay (RIA). Both methods measure ACTH 1-39 in unextracted plasma and cross-react less than 0.5% with ACTH fragments. ACTH levels were assessed in 103 patient samples: for concentrations in the range 5.3-1000 ng/L, results by the two methods were significantly correlated (r = 0.82, n = 86, P less than 0.001). The IRMA was more sensitive and had a wider working range than the RIA (detection limits 5.3 ng/L (IRMA) vs 11 ng/L (RIA); CV less than 10% between 19 and 1000 ng/L (IRMA) and CV less than 15% between 30 and 400 ng/L (RIA). In two patients for whom discrepant results were obtained, measurement of ACTH by bioassay and ACTH precursors by direct IRMA demonstrated the greater accuracy of the ACTH IRMA result. The improved performance of the IRMA combined with its many practical advantages compared to RIA, make it ideal for use in detailed clinical and physiological studies which have previously been hampered by the poor reliability of ACTH measurement.
Family screening in medullary thyroid carcinoma presenting without a family history.
Systematic screening of the families of a series of 39 patients with apparently sporadic medullary thyroid carcinoma detected seven new cases in four families. A negative family history in a patient presenting with medullary thyroid carcinoma is not reliable in excluding familial disease, and family screening should be considered for new patients with medullary thyroid carcinoma.
Failure to preserve fertility in patients with Hodgkin's disease.
The hypothesis that the "down-regulated" gonad is less vulnerable to the effects of cytotoxic chemotherapy for advanced Hodgkin's disease has been investigated. Thirty men and eighteen women were randomly allocated to receive an agonist analogue of gonadotrophin-releasing hormone prior to, and for the duration of, cytotoxic chemotherapy. Buserelin (d-Ser-[TBU]6 LHRH ethylamide) was prescribed in two different dosage schedules to twenty men, and in a single dosage schedule to eight women. A standard gonadotrophin-releasing hormone test (GnRH 100 micrograms) was performed 1 week prior to and on day 1 of each cycle of chemotherapy. In all patients peak luteinizing hormone responses to GnRH were suppressed throughout treatment. The higher of the two dosage schedules used in the men caused more effective suppression of luteinizing hormone, and both regimens led to an initial suppression of peak follicle-stimulating hormone responses to GnRH, which was not maintained. At follow-up assessment up to 3 years from the completion of treatment, all men treated with buserelin were profoundly oligospermic and four of the eight women were amenorrhoeic. All ten male controls were profoundly oligospermic, and six of nine female controls were amenorrhoeic. In the dosages and schedules investigated, buserelin was ineffective in conserving fertility.
A comparison of phenformin and metformin in the treatment of maturity onset diabetes.
A comparison of the effects of two dose levels of phenformin (50 mg once and twice daily) and metformin (850 mg twice daily and 1,700 mg twice daily) has been undertaken in 24 maturity onset diabetics whose diabetes had remained inadequately controlled with dietary measures alone. Both biguanides effectively reduced the fasting blood sugar and body weight of the patients, metformin apparently having a greater effect on blood sugar than phenformin. Serum triglycerides were lower on the larger dose of metformin than on either dose of phenformin. Both drugs in the larger doses reduced the serum cholesterol. Side effects were more common with metformin, particularly in the higher dosage and overall control of the diabetes was achieved in the same proportion of patients (33%).