We have devised rapid analyses for mercury exploiting the high affinity of dithiocarbamate chelators for the mercuric ion. Our first assay is based on a sandwich chelate formed by a ligand supported on the well of an ELISA plate, Hg2+ ion of the investigated sample, and another ligand bound to a reporter enzyme. The second assay utilizes competitive binding of the analyte Hg2+ ions versus an organomercury conjugate to a chelating conjugate. Low ppb sensitivity and high selectivity for Hg2+ ions have been achieved in our pilot studies.

Chelating Agents↗

PubMedDate not supplied

A new experimental model for drug studies: effects of phenobarbital and phenytoin on photosensitivity in the lateral geniculate-kindled cat.

Photosensitivity was acquired as a result of kindling in the lateral geniculate body (GL), and the GL-kindled cat pretreated with DL-allylglycine showed a stable level of photosensitivity. To test the usefulness as a model for the evaluation of anticonvulsant drugs, the effects of phenobarbital (PB) and phenytoin (PHT) on photosensitivity were studied in the GL-kindled cat under DL-allylglycine. PB (5 and 10 mg/kg intravenously, i.v.) completely suppressed photically induced seizures in most subjects at plasma concentrations of 7-16 micrograms/ml, and this anticonvulsant action persisted for at least 4 h after the injection. PHT (15 mg/kg, i.v.) at plasma concentrations of 9-15 micrograms/ml produced toxic signs, e.g., pupil dilatation, hypersalivation, and tachypnea. At this dose, PHT was inactive against photically induced myoclonus but prevented the elicitation of a generalized tonic-clonic convulsion. From these results showing that the effects of anticonvulsant drugs on photically induced seizures can be assessed in relation to plasma concentration and acute neurologic toxicity, we suggest that the GL-kindled cat is a potentially useful animal model of epilepsy for testing the efficacy of anticonvulsant drugs.

Allylglycine↗

PubMedDate not supplied

Characterization of a novel activation-specific antiplatelet monoclonal antibody.

We developed a murine monoclonal antibody (KmT-50) which binds to a protein expressed on the surface of human platelets after activation. KmT-50 is an immunoglobulin G1 monoclonal antibody that recognizes a 50-kD antigen localized in intracellular organelles and the open canalicular system of unstimulated platelets. After platelets were stimulated, the antigen was secreted via the surface-connected canalicular system and exposed on the platelet membrane. KmT-50 bound not only to human platelets, but also to rabbit and monkey platelets. This new antibody may be useful for experimental studies on thrombosis and hemostasis.

Animals↗

PubMedDate not supplied

Molecular basis of proteolytic activation of Sendai virus infection and the defensive compounds for infection.

It has been proposed that the pathogenicity of Sendai virus is primarily determined by a host cellular protease(s) that activates viral infectivity by proteolytic cleavage of envelope fusion glycoproteins. We isolated a trypsin-like serine protease, tryptase Clara, localized in and secreted from Clara cells of the bronchial epithelium of rats. The enzyme specifically cleaved the precursor of fusion glycoprotein F0 of Sendai virus at residue Arg116 in the consensus cleavage motif, Gln(Glu)-X-Arg, resulting in the presentation of the membrane fusion domain in the amino-terminus of the F1 subunit. Administration of an antibody against tryptase Clara in the airway significantly inhibited the activation of progeny virus and multiple cycles of viral replication, thus reducing the mortality rate. These findings indicate that tryptase Clara in the airway is a primary determinant of Sendai virus infection and that proteolytic activation occurs extracellularly. We identified two cellular inhibitory compounds against tryptase Clara in bronchial lavage. One was a mucus protease inhibitor, a major serine protease inhibitor of granulocyte elastase in the lining fluids of the human respiratory tract, and the other was a pulmonary surfactant which may adsorb the enzyme, resulting in its inactivation. These compounds inhibited virus activation by tryptase Clara in vitro and in vivo, but did not themselves affect the hemagglutination and the infectivity of the virus. The functional domain of the mucus protease inhibitor against the enzyme, which is organized in two homologous N- and C-terminal domains, is located in the C-terminal. Administration of these compounds in the airway may be useful for preventing infection with Sendai virus.

Animals↗