Methods of assessing the biocompatibility of materials for use in medical devices were evaluated. Ten materials were tested using quantitative, objectively graded in vitro biochemical and functional assays employing four cell lines (CCL 1, 74, 76, and 131) used in previous work and five primary cell types (human lymphocytes, polymorphonuclear leukocytes, and mixed leukocytes, mouse macrophages, and mouse embryo). The biochemical methods (DNA synthesis, protein synthesis, and ATP activity) demonstrated good agreement in toxicity ranking of the materials, regardless of which cell culture was used and, also, the cell cultures responded similarly for each method. Methods that measured functional characteristics of cells (adhesion and phagocytosis) were highly sensitive but had low toxicity ranking agreement and reproducibility. Assays (defined as method and cell culture combinations) using cell lines were more reproducible than assays using primary cell types. Significant differences in sensitivity were noted among the assay systems for particular material types. The in vitro assays were more sensitive to differences in material composition than was a 90-day assay by subcutaneous implantation in rats.

Adenosine Triphosphate↗

PubMedDate not supplied

Development of a radioimmunoassay procedure for 4-acetamidobiphenyl, a metabolite of the chemical carcinogen 4-aminobiphenyl, in urine.

The synthetic chemical 4-aminobiphenyl (4-ABP) has been shown to be a bladder carcinogen in both man and animals. A valid radioimmunoassay for a metabolite of 4-ABP has been developed as a means to monitor potential human exposure to 4-ABP. The antibody was produced by the immunization of two female New Zealand White rabbits and was found to be highly specific for 4-acetamidobiphenyl (4-AABP), the acetylated metabolite of 4-ABP. At an initial dilution of 1/5000, the antisera bound 45% of the [125I]-labeled derivative of 4-ABP. This derivative was prepared by coupling 4-hemisuccinamidobiphenyl (4-HSBP) with tyramine, and then radioiodinating this compound using the enzymatic lactoperoxidase method. The dose of 4-acetamidobiphenyl which would displace 50% of the labeled hapten initially bound to the antiserum, was about 1 ng (4.8 pmol). Scatchard analysis of the standard curve binding data indicated the presence of at least two populations of binding sites. The equilibrium association constant for the higher binding affinity component was 2.8 x 10(8) Liters/mole. A series of 210 randomly selected human urine control samples were analyzed and a nonspecific background contribution of 1.67 +/- 0.07 ng (mean + S.E.) of "4-acetamidobiphenyl"/mL urine was found.

Aminobiphenyl Compounds↗

PubMedDate not supplied

Validation of a radioimmunoassay procedure for N,N'-diacetylbenzidine, a metabolite of the chemical carcinogen benzidine, in urine.

The biaryl amine benzidine has been reported to produce tumors of the bladder in both man and animals. We have developed and validated a radioimmunoassay (RIA) procedure for monitoring potential human exposure to benzidine through detection in urine samples of one of its known urinary metabolites. The antibody used in the assay was produced in rabbits and is specific for N,N'-diacetylbenzidine (N,N'-DAB). At a 1/15000 initial dilution, this antiserum bound 50% of an iodinated tracer [125I]-N4'-[4-hydroxyphenethylaminohemisuccinyl]-4-acetamido-4-aminobiphenyl. One hundred pg (0.373 pmol) of N,N'-DAB displaced 50% of the tracer initially bound to the antiserum. The validity of the RIA procedure was established by the parallelism exhibited between the standard curve and aliquots of spiked human urine samples. The RIA has good spiked human urine samples. The RIA has good sensitivity (average minimal detectable dose less than 10 pg) and reproducibility (within-and between-assay coefficients of variation at midrange of the standard curve were 3.94 and 12.48, respectively). A series of 109 randomly selected human urine control samples were analyzed and a nonspecific interference of 0.52 +/- 0.04 ng of N,N'-DAB/mL urine was found.

Animals↗