The free amino acid content of the hippocampus, obtained at postmortem, has been analysed in cases of Alzheimer's disease and compared with normal cases. There were no significant differences in the levels of 23 amino acids including the transmitter candidates gamma-aminobutyric, glutamic or aspartic acids. This finding is interpreted in relation to present knowledge of transmitter pathways in the region of the hippocampus. A tendency for some amino acids to be increased in the Alzheimer group reached statistical significance for arginine. This observation is consistent with increased proteolytic or peptidase activity in Alzheimer's disease.

Six assays for protein in urine were compared for linearity, ease of standardization, precision, comparability of assay values, technical ease of assay, and current cost. The assays investigated were three dye-binding techniques, a recent turbidimetric technique, the trichloroacetic acid--biuret reaction, and a tannic acid protein precipitation reaction with ferric chloride. All assays suffered from standardization problems, although the biuret method showed the best analytical recovery of albumin and gamma-globulin. The tannic acid/ferric chloride method is dependent on sample pH. The turbidimetric assay exhibited the greatest imprecision; i.e., CVs were 19.5% at a protein concentration of 0.13 g/L and 6.0% at a protein concentration of 1.3 g/L. On the basis of all the factors assessed, we conclude that the Pesce/Strande Ponceau-S and the Bio-Rad Coomassie Brilliant Blue dye-binding techniques offer certain advantages over the other assays studied.

Serum parathyroid hormone (PTH) levels in 6 patients who had received parathyroid tissue autografts were studied. Samples were taken from graft and non-graft arms both pre- and post-dialysis. Each sample was analysed using two PTH assays, one measuring C-terminal PTH and the other measuring the intact PTH molecule. For both pre- and post-dialysis samples an appreciably greater difference was seen between the graft and non-graft arms using the intact assay. A patient with suspected ectopic PTH production showed a very much reduced differential between the two sampling sites with both assays. We suggest that the intact PTH assay is of greater clinical utility in the localisation of ectopic glands and monitoring of graft function than the commonly used C-terminal assays.

We assessed the LKB "Delfia" (time-resolved dissociation-enhanced lanthanide fluoroimmunoassay) and the Amersham "Amerlite" (enhanced luminescent immunometry) assays of thyrotropin in serum. Both assays are sensitive (respective detection limits: 0.02 and 0.04 milli-int. unit/L) and have very good within- and between-batch precision over a wide range of thyrotropin concentrations. Results by the two methods correlate well (r = 0.992); the regression equation is: Amerlite = 0.915 Delfia - 0.33 milli-int. unit/L. The standard curve for the Delfia assay was linear, but that for the Amerlite assay showed some deviation from linearity below 0.5 milli-int. unit/L. Both assays have a negative bias in comparison with radiolabeled immunoradiometric assays, as judged by results for samples from the Quality Assurance Scheme. Both assays discriminate well between hyper-, hypo-, and euthyroid subjects, and results for thyrotropin for most patients with nonthyroidal illness were within the euthyroid reference interval. Both assays are convenient to perform and are based on systems that provide a viable alternative to radioimmunoassay.

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