Consideration on some hormone binding proteins patterns during pregnancy.

Serum concentrations of sex hormone binding globulin, transcortin, thyroxine binding globulin, transthyretin together with retinol binding protein, ceruloplasmin, transferrin and albumin were measured sequentially in pregnant women in order to derive more definite suppositions relating to the prime function of hormone binding proteins. Thus, the fact that except for transthyretin all other specific hormone binding proteins exhibited appreciable but significantly variable increases would suggest: a) the apparent existence of more complex mechanisms regulating protein metabolism during pregnancy than hitherto postulated (i.e. the general notion of an integrated estrogen influence); b) a major and distinctive role for each of the hormone binding proteins is plausible since alterations in hormonal requirements by the fetus as pregnancy progresses can not be provided by the almost constant transplacental transfer rate of the "free" hormone moiety.

Ultrafiltrable copper and related analytes in maternal and cord blood.

We utilized the Amicon micropartition system (MPS-1) to prepare ultrafiltrates of serum for evaluating non-protein-bound copper (NPBCu). The method is rapid (a usual turnaround time less than 2 h), practical (only 1 mL of serum is required), and reproducible (average CV = 5.7% within assay and 9.3% between assays). Using this technique, we determined that (a) NPBCu in serum appeared to be fairly stable, showing little variation among subjects in different physiological conditions (normal female, pregnancy, or fetal samples); and (b) of all copper fractions studied, only NPBCu appeared to correlate between maternal concentrations and cord counterparts at delivery. Thus the NPBCu fraction may be appreciably involved in the overall mechanism of copper nutritional supply from mother to fetus.

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.

Deprecating the diagnostic significance of free thyroxine levels in human serum.

Prime diagnostic importance has been postulated for the measurement of free thyroxine in human serum. During the past decade various innovative and routinely applicable techniques have been developed for its assay, and claims for their superior performance in clinical practice have subsequently been made. However, in our opinion, based on current literature concerning thyroxine metabolism together with basic information about the physicochemical characteristics that govern its intravascular distribution, it seems appropriate to indicate caution against overestimating the diagnostic sensitivity attributed to free thyroxine measurement irrespective of assay methodology and its conceptual elegance.

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.

Distribution of thyroid diseases and evaluation of laboratory parameters used in their diagnosis.

A retrospective rationalization of commonly performed tests and procedures for the assessment of patients with suspected thyroid disease was attempted. The final diagnosis, in 392 consecutive new referrals to a central thyroid clinic, was primarily established by combined criteria of clinical/scintigraphic/cytopathologic findings. Detailed statistical analysis and evaluation of the accumulated data have demonstrated that: (a) only 15.8% of patients exhibited measurable thyrometabolic disturbances, thus indicating a rather limited scope for the application of laboratory tests in screening for thyroid diseases; (b) the measurement of serum total thyroxine with the thyroid hormone uptake test and the derivation of the free thyroxine index constitute, at present, the most appropriate initial in vitro laboratory procedure for assessing thyrometabolic function; and (c) recently available innovative methods for estimating serum levels of free thyroid hormones have no advantages over established assays.

A simple and economical method for the preparation of adsorbents for the thyroid hormone uptake test.

A low-cost and simple method has been developed for the preparation of human or animal protein-based adsorbents for use in the thyroid hormone uptake test. A combination of sodium sulphate precipitation and glutaraldehyde polymerisation of pooled whole serum or purified albumin preparations was employed to yield a fine solid-phase suspension which eliminates the need for capping and rotating assay tubes. Results for 107 samples obtained by this method correlated well with those obtained by use of a commercial kit.

Clinical and laboratory evaluation of a commercial kit for measurement of serum free thyroxin ("Amerlex Free T4").

Different indexes of thyroid function were determined in conjunction with values obtained with a new commercial radioimmunoassay kit for serum free thyroxin, in 49 apparently healthy subjects, 87 pregnant women, and 142 outpatients attending the thyroid clinic. The results indicate a diagnostic success rate of 88% when free thyroxin was measured instead of estimating the so-called free thyroxin index. Furthermore, in three cases of papillary carcinoma the concentration of free thyroxin was increased, although all the other laboratory tests indicated a euthyroid state. Technically, the method is simple, rapid, and precise, and it would be of most value in the small hospital laboratory lacking the facilities of a comprehensive thyroid-function test service.

Adrenal-seminal-pituitary protein levels in maternal serum and amniotic fluid.

Adrenal-seminal-pituitary protein (ASP) was measured by radioimmunoassay in maternal serum and amniotic fluid samples obtained throughout pregnancy. Levels of ASP in maternal circulation showed a steady rise from a mean of 350 micrograms/l at ten weeks gestation to 526 micrograms/l at term. There was a further rise in ASP levels during labour. In contrast, a slight decline in amniotic fluid ASP was observed throughout pregnancy but the levels rose sharply during labour. These findings are in agreement with the hypothesis that ASP is closely associated with prostaglandin physiology.

Identification and purification of a new protein from water-soluble extracts of human adrenal gland.

An homogenate of human foetal adrenal gland was subjected to negative immunoabsorption by column chromatography using anti-whole human serum coupled to Sepharose 4B. Two peaks were eluted and used to immunize rabbits. The antisera produced were absorbed and tested for specificity by double immunodiffusion. Two antigens, which appeared to be specific to the adrenal gland, were identified having molecular weights of 25 000 and 65 000 as determined by gel filtration. The lower molecular weight antigen was isolated by physicochemical methods and found to be a protein. The amino acid composition is reported.

Development of a radioimmunoassay for adrenal specific protein: its measurement in biological fluids and tissues.

A radioimmunoassay for a new human adrenal specific protein (ASP) is described. The assay has a lower limit of detection of approximately 50 micrograms/l. The ASP extracted and purified from adrenal glands was used for standardization, radio-iodination and immunization of rabbits. Adrenal specific protein can be detected in normal human serum and plasma (240 +/- 80 and 190 +/- 60 micrograms/ml (means +/- S.D.) respectively), tissue levels were found in extracts of adrenal medulla, with appreciable amounts in the adrenal cortex, pituitary gland, seminal vesicle and testis, and low levels in all other tissues examined. The highest concentrations in biological fluids were found in seminal plasma and to a lesser extent in milk and menstrual fluid.

A simple and reliable method for the purification of human alphafetoprotein (AFP) from amniotic fluid and fetal livers.

Highly purified human alphafetoprotein has been isolated from amniotic fluid and fetal livers by a combination of salting-out, and gel filtration, ion exchange, and concanavalin-A affinity chromatography. They yield ranged from 25 to 37%, and purity was demonstrated by radioimmunodiffusion, crossed radioimmunoelectrophoresis, polyacrylamide gel electrophoresis, and comparison with other preparations by radioimmunoassay. Immunochemical potency by weight of alphafetoprotein purified from amniotic fluid was similar to that from fetal liver, with molecular weights of 70 000 and 68 500 respectively. The amino acid and carbohydrate composition is also reported. This physicochemical method is relatively simple and inexpensive and is well suited for large scale production.