Pesticides and their metabolites in selected Italian groundwater and surface water used for drinking.

The control of groundwater and surface water quality in relation to the presence of pesticides and their metabolites is a rather complicated task. National and local authorities with the responsibility to guarantee an adequate quality of water cannot rely on international guidelines for monitoring activities. In a national project, forty-three pesticides and pesticide metabolites were selected on the basis of sale, monitoring and physical-chemical data, and investigated from some of the main Italian agricultural areas, susceptible to pesticide contamination.

Comparison of time-resolved fluoroimmunoassay and immunoenzymometric assay for clenbuterol.

A time-resolved fluoroimmunoassay (TR-FIA) for the direct determination of clenbuterol residues in horse urine using a highly specific monoclonal antibody has been compared with an immunoenzymometric assay (IEMA). The sensitivity of both methods was 10 pg; the calibration curve was linear between 10 and 10(5) pg for the TR-FIA and between 10 and 10(4) pg for the IEMA.

Determination of aflatoxin B1 in agricultural commodities by time-resolved fluoroimmunoassay and immunoenzymometric assay.

A time-resolved fluoroimmunoassay (TR-FIA) and an immunoenzymometric assay (IEMA) were applied for the measurement of aflatoxin B1 in soya seeds, dried figs and raisins. The extraction procedure was simple and no clean-up was found to be necessary. Limits of detection were 0.

Relationship between the intrahepatic expression of 'e' and 'c' epitopes of the nucleocapsid protein of hepatitis B virus and viraemia.

The relationship between hepatitis B viraemia and intrahepatic HBV nucleocapsid proteins (HBcAg and HBeAg) was studied in 18 patients with chronic hepatitis B. Monoclonal antibodies (MoABs) were obtained in BALB/c mice primed with recombinant HBV nucleocapsid proteins. Four MoABs reacting with recombinant proteins gave positive results in competitive assays.

Alpha-fetoprotein monoclonal assay: preliminary clinical findings in a high risk population.

A two-site solid phase immunoradiometric assay was developed for measurement of human alpha-fetoprotein, utilizing two high-affinity monoclonal antibodies directed against distinct and separate epitopes on the proteic structure. The analytical sensitivity of the assay is 0.5 ng/ml.

Synergistic neutralization of rubella virus by monoclonal antibodies to viral haemagglutinin.

Using murine monoclonal antibodies (MAbs) to rubella virus haemagglutinin, five epitopes were identified in competitive ELISA binding assays: A, B, D and E by haemagglutination-inhibiting (HI) MAbs with no neutralizing (Nt) activity, and C by a MAb with neither activity. However, when HI and Nt activities were determined in the presence of anti-mouse immunoglobulins, epitopes A, B and D were defined by both HI and Nt MAbs, whereas epitopes C and E were identified by HI MAbs without Nt activity. A synergistic Nt activity, in the absence of anti-mouse immunoglobulins, was displayed by mixtures of antibodies of different epitope groups.

Development and evaluation of a capture enzyme-linked immunosorbent assay for determination of rubella immunoglobulin M using monoclonal antibodies.

A capture enzyme-linked immunosorbent assay (ELISA) for detection of virus-specific immunoglobulin M (IgM) antibody was developed which used a panel of labeled monoclonal antibodies to rubella virus hemagglutinin. The rapidity of the test system was increased by using, after 1-h incubation of the test serum, a second 1-h incubation of the serum with a mixture of viral antigen and labeled monoclonal antibody. The new assay was tested for specificity on 371 human sera from people without any recent contact with rubella virus; of these, 66 were sera selected from people with rheumatoid factor or IgM antibody to human cytomegalovirus, Epstein-Barr virus, or other viruses.

Immunoscintigraphy of colorectal carcinoma with F (ab')2 fragments of anti-CEA monoclonal antibody.

A monoclonal antibody to carcinoembryonic antigen (CEA) (F023C5), belonging to IgG1 class, was obtained by cell fusion technique. Preliminary screening on different tissues was performed with immunoperoxidase staining, which showed good specificity of the antibody for gastric and colorectal carcinomas. F(ab')2 fragments were subsequently prepared and labeled with 131I and 111In.

Imaging with 131I-labeled monoclonal antibodies to a high-molecular-weight melanoma-associated antigen in patients with melanoma: efficacy of whole immunoglobulin and its F(ab')2 fragments.

In vitro experiments selected optimal conditions to radiolabel with 131I the whole immunoglobulin and F(ab')2 fragments of the monoclonal antibody (MoAb) 225.28S to a high-molecular-weight melanoma-associated antigen (HMW-MAA). Injection of the radiolabeled whole immunoglobulin and F(ab')2 fragments of the MoAb 225.

ELISA for specific anti-toxoplasma IgM antibodies: aspects related to serum interference.

Two different methods were used to prepare solid-phase antigen (Ag) from soluble extracts of tachyzoites of Toxoplasma gondii: (A) physical adsorption on polystyrene beads; and (B) formaldehyde fixation of Ag previously dried in microtitration wells. In both cases a horseradish peroxidase conjugate with anti-IgM IgG was used as tracer. The assay scheme consisted of sequential incubations of diluted serum samples and tracer solution (1 or 2 h, 37 degrees C), colour development in the presence of substrate (10 min at room temperature), addition of H2SO4, and absorbance reading at 492 nm.

Use of an enzyme-linked immunosorbent assay for screening hybridoma antibodies against hepatitis B surface antigen.

An enzyme-linked immunosorbent assay (ELISA) was developed for screening production of monoclonal antibodies with specificity for HBsAg. Mouse hybridoma IgG were firstly extracted from assay medium with goat anti-mouse IgG adsorbed on polystyrene beads. The specific antibody was revealed by saturation with HBs antigen from human positive sera followed by reaction with specific sheep anti-HBs antibody conjugated with peroxidase.

ELISA for antibody measurement: aspects related to data expression.

In an ELISA for antitoxoplasma IgG (antigen-coated polystyrene beads, horseradish peroxidase-coupled IgG or staphylococcal protein A), 3 modes of expressing the analytical results were considered, i.e. end-point antibody titre, untransformed absorbance reading at a single sample dilution, and antibody-activity unit from a calibration response curve (reference sera as calibrators).

ELISA for toxoplasma antibody detection: a comparison with other serodiagnostic tests.

An ELISA method was developed for the measurement of toxoplasma IgG antibodies in human serum using antigen-coated polystyrene beads as a solid phase and anti human IgG-horse radish peroxidase conjugate as an enzymatic tracer. In order to assess ELISA sensitivity and specificity, a between methods comparison was made using 'conventional' serological tests as reference (dye-test, crossover-linked immunoassay, passive haemagglutination, indirect immunofluorescence). From an analysis of the group classifications obtained some considerations emerged: the ELISA specificity looks comparable with that of the 'reference' tests, as no sample classified as negative by all these tests was ELISA-positive, and vice versa; ELISA appears to correlate better with haemagglutination and immunofluorescence, on the basis of the respective class frequencies; in particular, the number of positives, which is much lower for the dye-test and crossover-linked immunoassay, suggests that a higher sensitivity is reached in the former cases.