Free amino acids, copper, iron and zinc composition in sera of patients with thyrometabolic diseases.

Free amino acids together with copper, iron and zinc were measured in sera of 67 adult patients with thyrotoxicosis (n = 29) or hypothyroidism (n = 38). In contradistinction to the almost indifferences exhibited by the three metals, many amino acids displayed significant relationships with the thyrometabolic activity (mainly tyrosine and arginine with r values of 0.5 and 0.44, respectively). Additional analyses revealed certain patterns, between trace metals and amino acids, which conferred challenging difficulties to interpretation. Thus while zinc was associated positively with some amino acids (such as glutamic acid and alanine), copper correlated almost invariably in a negative manner with citrulline, alpha-amino-butyric acid, proline, glycine and valine. This new information should contribute to our knowledge of the complex metabolism of both trace metals and amino acids.

Utilization of a computer-controlled laboratory workstation (Biomek 1000) in routine radioimmunoassay laboratory.

The suitability and performance characteristics of a recently introduced computer-controlled laboratory workstation (Biomek 1000) for use in automating sample transfer and reagent additions in radioimmunoassay techniques were assessed. The system is based on the use of disposable tips and, therefore, reduces any possible sample carry-over and eliminates the need for priming with the subsequent reduction in cost of reagents. However, the machine lacks the useful option of liquid-level sensing facility. Acceptable technical performance in terms of precision, accuracy and throughput was obtained with the Biomek 1000 which complied with international recommendations on the safety of hospital laboratory equipment.

Non-separation radioassay for cortisol binding capacity in human serum.

A radioassay for the measurement of cortisol binding capacity in human serum was developed and the results validated by radioimmunoassay of serum corticosteroid binding globulin. The mini-scale method is simple, reliable and rapid, and avoids separation of partitioned phases. The linear correlation between the free cortisol index and free cortisol concentration as calculated by the two methods utilizing serum samples with normal and abnormal protein concentrations was r = 0.962 (n = 114, p less than 0.001) and the regression equation was y = 3.516 x - 2.632. The technique requires no preparation of reagents, and the assay can be performed in 45 minutes using 0.05 ml of serum or plasma.