Julia M. Potter

Binding of cortisol to human albumin and serum: the effect of protein concentration.

Abstract Using equilibrium dialysis at 37°, the binding of two Cortisol concentrations to both human albumin and serum were examined as a function of protein concentration. The range of protein concentration included the normal physiological range for albumin and cortisol. The use of dextran outside the dialysis sacs enabled the inside protein concentration to be stabilized against dilution resulting from colloid osmotic fluid movement. Furthermore, this enabled the protein mass within a given series to remain constant whilst allowing predetermined concentration changes. Scatchard analyses show that as the protein concentration decreases in either serum or albumin the binding affinity and/or number of binding sites for cortisol increases. Colloid osmotic fluid movements indicate that albumin behaves anomalously at relatively high concentration. This anomaly indicated by the presence of an apparently higher molecular weight species appears to be related to the concentration of cortisol present. In serum, the influence of corticosteroid binding globulin on cortisol binding is concentration dependent. This was shown by an apparent increase in binding site availability with protein dilution.

Serum Uric Acid as a Marker of Pregnancy-Induced Hypertension

Summary: A prospective longitudinal study was conducted, looking at the changes in serum uric acid during pregnancy in women who were normotensive at initial presentation. In our sample of 78 women having a total of 88 singleton pregnancies, 13 developed pregnancy‐induced hypertension during labour only, whilst a further 6 developed hypertension during pregnancy. Women who developed hypertension had significantly higher uric acid levels than women who remained normotensive throughout. However, there was an appreciable overlap between the groups. Women with essential hypertension showed similar changes. We conclude that the serum uric acid level is an unreliable indicator of developing hypertension in the individual woman. However, a rapidly rising uric acid level should be viewed with caution.

Polymerization of human transcortin in plasma

Using radial immunodiffusion and antiserum raised against purified transcortin, polymers of native transcortin have been identified in plasma. They are characterized by multiple precipitin bands, the size of which diminishes on dilution, consistent with reversibility of this form of polymer. Spectrophotometric scans have been used to study the time course of polymerization in purified transcortin, in which dilution reversibility can be demonstrated also, and in which disaggregation may be produced by addition of sodium dodecyl sulphate and dithiothreitol, but apparently not by cortisol.

Altered in vitro lymphocyte response in childhood nephrotic syndrome

The immune system, and disturbed T lymphocyte function in particular, has previously been implicated in the pathogenesis of childhood idiopathic nephrotic syndrome. As this disorder is commonly responsive to steroid therapy, we set out to determine whether in vitro suppresion of lymphocyte blastogenic response to the mitogen phytohaemagglutinin (PHA) could predict the clinical situation. Comparing nine nephrotic children with nine healthy controls we were able to show the inhibitory prednisolone dose that suppressed lymphocyte blastogenesis by 50% (ID50) at a known concentration of PHA was significantly greater (P<0.005) for nephrotic individuals. However, the in vitro assay did not reliably predict the clinical response to prednisolone. This study further implicates altered lymphocyte function in the mechanisms underlying idiopathic nephrotic syndrome.

PURIFICATION OF AN ANTICOAGULANT FROM THE BODY FLUID OF ASCARIS SUUM

An anticoagulant has been purified from the body fluid of Ascaris suum by sequential passage through Sephadex G-50, CM-cellulose and Sephadex G-25 columns then treated with 2 M NaCl, passaged through a Sephadex G-25 column, separated from the phosphate buffer by precipitation of the latter with the CaCl2, then passaged through a Sephadex G-10 column in water. In the body fluid of the worm, the anticoagulant is ionically-bound to a carrier substance. The complex can be split by treatment with 2 M NaCl. The molecular weight of the anticoagulant is slightly less than 1400.

Type 1 Hyperlipoproteinaemia and Pregnancy

Whilst hyperlipoproteinaemia is a physiological accompaniment of normal pregnancy (Potter and Nestel, 1979), in patients with inherited disorders marked by hypertriglyceridaemia, the increase in plasma triglycerides in pregnancy may precipitate medical sequelae, placing the pregnancy and the patient at risk. The number of case reports concerning such patients are few (Glueck et al., 1980) and there is little information to guide the obstetrician and physician as to likely complications. The majority of cases which are reported concern the identification of women who present with complications such as pancreatitis during pregnancy and are subsequently found to have hypertriglyceridaemia (Millen et al., 1956; Adlersberg et al., 1959).

Calibration line determination of an heterologous antigen in radial immunodiffusion

Abstract Using known principles of radial immunodiffusion it is shown experimentally that an heterologous antigen may be quantified using an homologous antigen-antibody system. The proteins in which this is demonstrated are human serum albumin (the homologous antigen) and the plasma albumins of baboon (Papio hamadryas) and rhesus monkey (Macaca mulatta). Purification of the heterologous antigen is not required. The system also gives a measure of the degree of cross-reactivity between the homologous and heterologous antigens.