Summary.-Radioimmunoassay methods for the determination of oestradiol-17p and prolactin have been examined for their reliability and applied to the measurement of hormone concentrations in the plasmas from male and female rats. Prolactin was detectable in all samples (>7 ng RP-1 ng/ml) but the concentration of oestradiol-17p was below the sensitivity of the method (>0*10 ng /lOOml) in ovariectomized females. Plasma oestradiol-17p concentration rose gradrfally from metoestrus to proestrus and fell to barely detectable levels in oestrus. Plasma prolactin concentration was very variable even for rats in the same stage of the oestrous cycle but values were minimal in the afternoon of diestrus and a surge in secretion occurred in the afternoon of proestrus. In addition to the stage of the oestrous cycle, the prolactin concentration was influenced by mode of blood collection, degree of haemolysis and choice of serum or plasma. There was no correlation between the concentration of prolactin and that of oestradiol-17P in the same sample of plasma.IN THE RAT, the growth of experimental mammary tumours induced by the administration of the carcinogen 7,12-dimethylbenzanthracene (DMBA) has been reported to be influenced by both oestrogen (Dao and Sinha, 1972), and prolactin (Pearson, 1969). As a preliminary to an investigation of the role of these hormones in tumour growth, we have set up methods for their measurement by radioimmunoassay. The reliability of each method has been examined and the basal levels of each hormone have been measured at various stages during the oestrous cycle, in ovariectomized animals and in males. Although the fluctuations in plasma oestradiol-17/3 (Hori, Ide and Miyake, 1968;Yoshinaga, Hawkins and Stocker, 1969;Brown-Grant, Exley and Naftolin, 1970; Shaikh, 1971;Dupon and Kim, 1973), and plasma prolactin (Kwa and Verhofstad 1967; Niswender et al., 1968;Gay, Midgeley and Niswender, 1970;Amenomori, Chen and Meites, 1970;Neill and Reichert, 1971;Neill, 1972) during the oestrous cycle have been reported previously, the results of simultaneous measurements of both hormones in individual rats have not to our knowledge been published. MATERIALS AND METHODSAnimals.-Randomly bred SpragueDawley rats were maintained on a lighting; darkness schedule of 12 h L: 12 h D, with the lights switched on at 0700 hours. Vaginal smears were taken daily by lavage and the rats were followed for at least 2 cycles. Only rats with regular 4-day cycles were used and stage in the cycle was defined as previously described (Yoshinaga et al., 1969).Blood was withdrawn into a hepariniZed syringe from the abdominal aorta under ether anaesthesia except when otherwise stated. Blood samples were cooled in ice and the plasma was separated by centrifugation at 4 TC at approximately 1300 g. In one experiment, serum was prepared by the collection of non-heparinized blood, allowing the blood to clot for at least 2 h at 4 TC and centrifugation. Haemolysed plasma was prepared by the addition of water to heparinized blood

Summary A method to determine the binding of epidermal growth factor (EGF) to the particulate fraction of the cell has been established and evaluated using rat liver, human placenta, and tumours of human breast and brain. Little EGF receptor (EGFR) activity was detected in normal or benign tumour tissues except for meningioma (positive in 95% samples), but EGFR were present in 43% of 131 breast tumours and 75% of 55 primary cerebral tumours. Despite the strong inverse correlation between EGFR activity and oestrogen receptors in breast tumours and a tendency for high levels of EGFR activity to be associated with glioblastoma multiforme, analysis showed that EGFR was of little prognostic significance in patients with tumours of either breast or brain.

No abstract

No abstract

Oestrone sulphate, the oestrogen in highest concentration in the plasma, may play a role in the induction and growth of breast cancers. By enzymolysis and radioimmunoassay, oestrone sulphate concentrations were measured in 3 biological fluids. High concentrations of the conjugate (up to 775 nmol/l) were detected in breast cyst fluids from some premenopausal women, the concentrations in blood plasma (0.91-4.45 nmol/l) being much lower. Concentrations in the plasmas from postmenopausal women with (0.23-4.63 nmol/l) or without (0.18-1.27 nmol/l) breast cancer were still lower. Oestrone sulphate concentration in cow's milk or cream (0.49-0.67 nmol/l) was also low: dietary intake in these fluids is probably of little consequence. The capacity of breast tissues for hydrolysis of oestrone sulphate was examined in two ways: In tissue slices incubated with 85 pM (3H) oestrone sulphate solution at 37 degrees C, cancers (131-412 fmol/g tissue/hr) and adipose tissues (23-132 fmol/g tissue/hr) hydrolysed significantly more sulphate than did benign tissues (1-36 fmol/g tissue/hr). In tissue homogenates incubated with 5-25 microM [3H] oestrone sulphate at 37 degrees much higher capacities for hydrolysis (nmol/g tissue/hr) were demonstrated with a Km of 2-16.5 microM: cancers (34-394) and benign tissues (9-485) had significantly higher sulphatase activities than adipose tissues (9-39). On a protein basis, however, the sulphatase activities in the 3 tissues were comparable. It is concluded that oestrone sulphate is present in breast cysts and blood plasma and that in vitro, the conjugated hormone can be hydrolysed by breast tissues. The biological significance of these findings in vivo remains to be established.