We describe a homogeneous enzyme immunoassay for measurement of cannabinoid metabolites, as well as delta9-tetrahydrocannabinol (I) in urine. Malate dehydrogenase from pig heart mitochondria was labeled with a derivative of I. The compound used to calibrate the assay was the I metabolite, 11-nor-delta9-tetrahydrocannabinol-9-carboxylic acid (II). With 15 microgram of II per liter of urine as the cutoff concentration, the assay can detect 25 microgram of II per liter with greater than 95% confidence. A positive response was obtained for urine specimens assayed within 30 min after exposure to cannabinoids. However, the persistence of metabolites of I in urine indicates that assay of this fluid is useful as an indicator of cannabinoid use but not as an indicator of intoxication.
A method is described for the detection of immunoglobulin M (IgM) antibodies to Toxoplasma gondii by using latex particles coated with antigens of the organism. An excellent qualitative agreement was noted when the latex method was compared with other tests for the detection of IgM toxoplasma antibodies. The method is simple and inexpensive to perform and does not require the use of whole killed organisms or an enzyme conjugate.
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