Progestin receptors in meningiomas. Comparison of cytosolic assays with immunocytochemical identification in cryostat and paraffin sections.

The results are reported of ligand binding and enzyme immunoassays in tumour cytosols, and of immunoperoxidase assays in cryostat and paraffin sections measuring oestrogen (ER) and progestin receptors (PR) in 22 meningiomas and three non-meningioma tumours (two neurinomas and one haemangiopericytoma). With regard to the meningioma tissues, cytochemical immunoperoxidase PR-staining was present in all cryostat sections and in all but one of the paraffin sections. There was a good degree of qualitative accordance between all assay methods; they revealed the picture of "typical" meningioma: high PR and low ER. In this series, immunoperoxidase staining for the detection of PR-receptors, both in cryostat and paraffin sections, rendered encouraging results, thus offering a method for the detection of progestin receptors, which can compete with cytosolic methods.

Diamine oxidase activity in amniotic fluid for diagnosis of ruptured membranes.

Diamine oxidase in vaginal effluent is used as a parameter for ascertaining the state of fetal membranes. A new method using tritiated putrescine as a substrate is described for the determination of diamine oxidase in amniotic fluid and vaginal effluents. A number of tests are used for the diagnosis of premature rupture of fetal membranes. The described procedure for diamine oxidase activity determination can be used in general hospitals and has advantages over other parameters such as pH, glucose or fructose concentration, and the amniotic fluid crystallization test.

The diagnostic value of urinary transferrin compared to serum prostatic specific antigen (PSA) and prostatic acid phosphatase (PAP) in patients with prostatic cancer.

Urinary transferrin, serum prostatic acid phosphatase (PAP) and prostatic-specific antigen (PSA) concentrations were measured in patients with prostatic cancer, prostatitis, benign prostatic hypertrophy (BPH) and in a control group. In contrast to recently published data it is concluded that urinary transferrin is not suitable as a tumor marker for prostatic carcinoma. Receiver Operating Characteristic curves were constructed to compare the diagnostic value of the different tests at different cutoff values. Sensitivity and specificity of the urinary marker are extremely low compared to the serum markers PAP and especially PSA, making the former not suitable as an additional marker.

Quantification of oestrogen receptors in breast cancer: radiochemical assay on cytosols and cryostat sections compared with semiquantitative immunocytochemical analysis.

A radiochemical oestrogen receptor assay on cytosol was correlated with a radiochemical and an immunohistochemical oestrogen receptor assay using cryostat sections from 50 breast cancer specimens. Oestrogen receptors were reliably quantitated in 6 micron cryostat sections with Scatchard analysis using radiolabelled oestradiol, and a good quantitative and qualitative relation with cytosol oestrogen receptor assay was found. Parallel sections were used for routine histological tissue verification and for direct comparison with immunohistochemistry for oestrogen receptor. Specific immunoperoxidase staining with a rat monoclonal antibody was scored by semiquantitative evaluation of the staining intensity of cancer cell nuclei. Oestrogen receptor scoring was highly reproducible when performed by the same observer. The semiquantitative immunohistochemical oestrogen receptor score correlated significantly better with the radiochemical assay on sections than with cytosol assay. Oestrogen receptor in breast cancer can be reliably assayed by semiquantitative evaluation of cryostat sections immunostained for oestrogen receptor, but only if the procedure is adequately standardised. The results underline the importance of cellular heterogeneity as a cause of variation in oestrogen receptor assay evaluation in breast cancer.

A comparative study on the diagnostic value of prostatic acid phosphatase (PAP) and prostatic specific antigen (PSA) in patients with carcinoma of the prostate gland.

Serum prostatic-specific antigen (PSA) and prostatic acid phosphatase (PAP) were determined simultaneously in 241 patients presented to the Urology Department. The patients consisted of 140 prostatic carcinoma patients (34 newly diagnosed and 106 previously treated) and 101 patients with benign prostatic hypertrophy (BPH). Prostatic acid phosphatase was measured by two different methods, an enzymatic method (PAP-EA, Boehringer) with tartrate inhibition and an immunoenzymetric assay (PAP-IEMA, Hybritech). The concentration of prostatic specific antigen in serum was measured using a recently introduced immunoradiometric assay (PSA-IRMA, Hybritech). Receiver operating characteristic curves were constructed to compare the diagnostic value of the different tests at different cutoff values. The diagnostic efficiencies of the PAP-EA and the PAP-IEMA appeared to be similar. A better diagnostic efficiency for PSA compared to PAP was found independent of the cutoff value. The upper-normal limit of 2.7 micrograms/l for PSA, as suggested by the manufacturer and mentioned in the literature introduces too many false-positive results. We therefore selected 10 micrograms/l as the upper-normal limit for PSA (sensitivity 57%, specificity 88%). Combined sensitivity found for PAP + PSA was 37% with a specificity of 97%. A literature survey is included to allow better comparison with data published elsewhere.

Is prostate-specific antigen the most useful marker for screening in prostate cancer?

Prostate-specific antigen (PSA) and prostatic acid phosphatase (PAP) levels were determined in 241 patients attending the Department of Urology. The population consisted of 140 prostate cancer patients (34 newly diagnosed and 106 under treatment) and 101 patients with benign prostatic hypertrophy (BPH). The diagnostic values of PAP measured by enzymatic assay (EA) and by immunoenzymetric assay (IEMA) appeared to be similar. Elevated PAP (IEMA) levels were found in 10% of the patients with BPH and in 38% of the cancer patients. PSA was measured by immunoradiometric assay (IRMA) and receiver operating characteristic curves were constructed to compare the diagnostic benefits of different cutoff values. PSA (10 micrograms/L) reached a specificity of 88% and a sensitivity of 46%. With a cutoff value of 2.7 micrograms/L, the sensitivity increased to 64%, whereas the specificity fell to 58%. It is concluded that PSA is the most useful marker as a screening test.

The need for a sufficient number of low level sera in comparisons of different serum vitamin B12 assays.

Eight radiochemical methods for the assay of vitamin B12 in serum were compared with the microbiological assay with Lactobacillus leichmannii ATCC 7830 using 198 individual sera of patients. There was a good agreement between the results of most samples with some kits and the microbiological assay. However, especially in the sera of vitamin B12-deficient patients large discrepancies between the results could occur. These variations were due to both the kits used and the performance of the assays in different laboratories. A sufficient number of non-pooled sera of vitamin B12-deficient patients should be included in investigations to validate radiochemical methods.

The determination of cortisol in human plasma: evaluation and comparison of seven assays.

In a comparative study, seven different methods for the determination of cortisol in human plasma were evaluated, using routine patient samples. Four of these methods used radioactive steroids (125I- or 3H-labelled) and in three no radioactivity was needed. For the statistical evaluation a direct 3H-radioimmunoassay was arbitrarily taken as the independent variable. It was found that all other methods correlated well with this assay. However, the simplest method, the fluorimetric, cannot be recommended mainly because of its non-specific fluorescence and troublesome interference from some widely-used drugs. Of the methods evaluated a radioimmunoassay is recommended. For laboratories having no equipment for measurements of radioactivity, the more elaborate and time-consuming fluorometric method of Clark may represent a good alternative.

Further investigations on the affinity chromatography of unlabeled and labeled cortisol-binding immunoglobulin.

A specific method for the isolation of cortisol-binding immunoglobulin from rabbit antiserum by affinity chromatography on sepharose-coupled haptene (sepharose-cortisol) is described. This isolation technique has the advantage that no nonspecific gamma-globulin is present in the eluate of the column; previous absorption of anti-BSA-globulin can be omitted. The nature of the isolated immunoglobulin is determined by immuno-electrophoresis. The same isolation procedure can be used for the purification of radioactive antibody for radioimmunometric assay after labeling the immunoglobulin with iodine-125.

The raising and characterization of cortisol-binding antiserum.

Synthesis of a cortisol-albumin compound and the raising of antibodies against cortisol in rabbits are described in detail. The steroid-protein complex is characterized by a number of reactions regarding the amount of cortisol coupled and the ability of the coupled steroid to react as such. The specificity of the harvested antiserum and transcortin towards the coupling of several related steroids are compared; the rabbit antiserum appears to be the more selective binding agent.