Determination of antimony in urine, blood and serum and in liver and lung tissues of infants by inductively coupled plasma mass spectrometry.

Methods are presented for the determination by ICP-MS of antimony in body fluids and tissues of infants. Urine, serum and whole blood specimens are prepared for analysis by simply diluting 200 microliters sample volumes (1 + 14) with water and adding indium as internal standard. Liver and lung tissues are digested using 16 M HNO3 either in open quartz vessels at 150 degrees C or in sealed vessels with microwave heating. The acid digests are diluted with water and indium is added as internal standard for ICP-MS measurements. All analyses were subjected to stringent internal quality control protocols. Accuracy was assessed by recoveries, repeated analyses and by analysis of NIST SRMs 1577a Bovine Liver and 1566a Oyster Tissue. Precisions of analyses were better than 5-10% in the ranges 0.1-0.3 microgram l-1 for urine, serum and blood; and at 7-25 ng g-1 in tissues. Detection limits were 0.7 ng g-1 in liver, 0.8 ng g-1 in lung, and 0.01 microgram l-1 in urine, serum and blood. The need to employ validated procedures for specimen collection and to give considerable attention to pre-analytical factors in order to avoid adventitious contamination with antimony is demonstrated.

Simplified test for detecting the resistance of herpes simplex virus to acyclovir.

The detection of herpes simplex virus (HSV) antigen by means of an enzyme amplified ELISA was investigated for rapid screening of acyclovir (ACV) resistance. Vero cell monolayers were inoculated in the presence of different concentrations of ACV. When cytopathic effect was present, the culture supernatants were tested by ELISA. The absorbance values were found to correlate with the results of virus yield and plaque reduction assays. The comparison between absorbance values obtained in the presence of 10 microM ACV and in the absence of drug provided the basis for a simplified sensitivity test. The use of a single ACV concentration allowed discrimination between ACV-resistant and ACV-sensitive reference strains, the detection of ACV-resistant virus mixed in the proportion of 10% with ACV-sensitive virus, and a study of the emergence of an ACV-resistant virus population in serial samples taken from experimental rabbit keratitis. The simplified susceptibility assay is a sensitive and convenient method for rapid screening of HSV resistance to ACV.

Serial measurements of Ca antigen in sera from patients with advanced malignant breast disease.

Ca antigen levels in serum samples from three groups of patients were assayed. From a survey of 173 patients with various malignancies, elevated levels were found most consistently in patients with metastatic breast cancer. Spearman rank correlation values of Ca and CEA values on individual serum samples, 0.3009, (n = 194), or individual and serial samples, 0.2406, (n = 264) from a total 194 patients with metastatic breast cancer showed that correlation between Ca and CEA values was poor. For a group of 20 patients within the 194, from whom fortnightly serial samples were available, serum levels for 10/20, measured retrospectively, corroborated clinical observations on the course of their disease, although only 4/20 showed marked elevations during active disease. No correlations between expression of the tumour marker and histological type of the primary tumour, age of the patient, site of recurrence nor aberrant elevation in response to cytotoxic drug could be found to explain the non-correspondence of marker behaviour and disease status in the remaining 10 patients. The indications from this small study are that serial Ca antigen serum measurement could be misleading in 50% of patients with metastatic breast cancer, and that the assay is unsuitable for follow-up of patients with breast cancer.

The selection and performance of monoclonal and polyclonal anti-respiratory syncytial virus (RS) antibodies in capture ELISAs for antigen detection.

Six monoclonal antibodies directed against fusion protein (F) or nucleoprotein (NP) of respiratory syncytial virus (RS) have been investigated in an antigen capture ELISA for virus detection. The potency, spectrum and pattern of reactivity were investigated with the intention of selecting antibodies reacting with RS-common antigen determinants and with complementary rather than competitive activity. Two anti-F protein antibodies satisfied these criteria and were used with enzyme amplified detection in a two site monoclonal assay (MCA/MCA) or as detectors with a polyclonal antibody as capture (PCA/MCA). Comparative studies were performed with immunofluorescence (FA) as the reference test and nasopharyngeal aspirates processed in different ways. The PCA/MCA assay was superior to that using monoclonal antibodies alone and gave results comparable to the reference method. However, the apparent sensitivity related to FA varied with the type of sample processing used. These results emphasise the need for a critical analysis of the factors which can influence the sensitivity of a particular assay system before judgements on relative sensitivity are made.

Herpes simplex virus detection by ELISA: effect of enzyme amplification, nature of lesion sampled and specimen treatment.

The relative sensitivity of two enzyme detection procedures was investigated in a simultaneous "monoclonal" ELISA for herpes simplex virus (HSV). A cyclical enzyme amplified detection system with alkaline phosphatase, rather than horse-radish peroxidase and a conventional chromogenic substrate, gave an increase in absolute sensitivity and a 20 to 30% increase in the detection of HSV in routine isolation-positive genital specimens collected in transport medium. The HSV detection rate, with both procedures, was shown to vary with the site and clinical stage of lesion sampled; it was highest with penile vesicular lesions. Direct extraction of the swab specimen in a small volume of diluent further increased the sensitivity of antigen detection giving positive and negative predictive values of 100 and 96% respectively. The overall sensitivity of HSV detection was equivalent to that obtained by isolation in cell culture. The amplified ELISA offers an alternative, rapid, simple, non-culture technique for routine HSV diagnosis that does not rely upon retention of virus viability.

Detection of Ca antigen in sera from normal individuals and patients with benign and malignant breast disease.

Two assay procedures, an inhibition radioimmunoassay (Inhibition-RIA) and an immunoradiometric assay (IRMA), were established for the detection of circulating tumour-associated Ca antigen. There was a good correlation between results (r = 0.987) but the Inhibition-RIA was selected for extended tests on human sera from patients with breast disease because of its greater ease and economy in use. Circulating Ca antigen was not exclusive to malignancy and the level failed to discriminate between patients with primary carcinoma and those with benign disease. Ca antigen was present in sera of 100 healthy individuals (median 7.1 micrograms ml-1, range 1.8-24.4 micrograms ml)-1, 39 patients with benign disease (median 9.9 micrograms ml-1, range 2.5- greater than 100 micrograms ml-1) and in 67 patients with primary carcinoma (median 11.0 micrograms ml-1, range 3.8- greater than 100 micrograms ml-1). Elevated Ca antigen levels were found in 50% of patients with metastatic spread (median 30.7 micrograms ml-1, range 8.2- greater than 100 micrograms ml-1) and in some patients with primary disease but further studies are needed to determine the prognostic significance. Immunochemical studies confirmed that Ca antigen is a normal serum product but its function is unclear.

Localisation of Ca and HMFG2 antigens in breast tissue by immunoperoxidase, immunofluorescence, and immunoelectron microscopy.

The reactivities of Ca1 and HMFG2 monoclonal antibodies were compared on paraffin wax embedded breast tissues using indirect immunoperoxidase. The expression of Ca antigen, like HMFG2, is not exclusive to malignancy: Ca was present in 41/53 (77%) and HMFG2 in 42/53 (79.2%) non-malignant conditions and both were present in 33/35 (94%) carcinomas. Similar results were obtained when cryostat sections were used. Both antigens showed striking similarities in their topographical distributions, although quantitative differences were seen. Their cellular and sub-cellular localisations were investigated by double labelling immunofluorescence and immunogold electron microscopy, which showed that the expression of Ca and HMFG2 antigens was closely associated on cell membranes but that the epitopes were distinct.

Measurement of antibody to poly (adenosine diphosphate-ribose): its diagnostic value in systemic lupus erythematosus.

Poly (ADP-ribose) and dsDNA binding activity have been measured in sera from 61 patients with systemic lupus erythematosus (SLE) and 188 control sera from 20 normal individuals, 144 patients with clinically similar diseases and 24 patients with drug-induced anti-nuclear antibodies (ANA). Elevated poly (ADP-ribose) binding was not observed with normal sera. Five of 144 samples from diseases entering the differential diagnosis of SLE gave raised poly (ADP-ribose) binding compared with 12 in the 125I-dsDNA binding. Only two of these false positive samples gave elevated binding in the 14C-dsDNA assay. The apparent high specificity of the poly(ADP-ribose) assay was not observed with samples containing drug-induced ANA where 62% had elevated binding values. The frequency with which the poly(ADP-ribose) assay was positive with SLE sera (sensitivity) was lower than either of the dsDNA assays. This low sensitivity and the high rate of false positives in patients with drug-induced ANA limit the value of the poly(ADP-ribose) assay as a diagnostic test for SLE. However the restriction of poly(ADP-ribose) antibody to SLE and patients with drug-induced ANA together with the known role of poly(ADP-ribose) in DNA excision repair suggest that the antibody may be of fundamental significance.