Lysis of egg phosphatidylcholine vesicles by tricyclic carboxamide antitumor agents

The stability of small unilamellar vesicles formed by egg phosphatidylcholine has been examined in the presence of 38 tricyclic carboxamide DNA-intercalating agents (19 phenylquinolines, 17 phenylbenzimidazoles, an acridine and an anthracene). Lysis of the vesicular membrane is time-dependent and also dependent on the concentration of the cytotoxic agent. The relative concentration of agent to cause a fixed degree of lysis in a fixed time, as measured by the release of encapsulated 6-carboxyfluorescein, is directly related to the relative hydrophobicity of the agents.     

Seroprevalence of Toxoplasma gondii in pregnant women and cats in Grenada, West Indies

Prevalence of antibodies against Toxoplasma gondii was studied in 534 pregnant women and 40 domestic cats in Grenada, West Indies. Antibodies (IgG) for T. gondii were sought in human sera by an enzyme-linked immunosorbent assay and in cat sera by using the modified agglutination test (MAT). Antibodies were found in 57 % of pregnant women. Seroprevalence increased with age; 51% of 15- to 19-yr-old women (100 total) had antibodies versus 60% of 20- to 24-yr-old women (127 total). Antibodies to T. gondii (MAT, 1:25 serum dilution) were found in 35% of cats; titers were 1:25 in 7 cats, 1:50 in 4 cats, and 1:500 in 3 cats. Epidemiological data suggested that the ingestion of food or water contaminated with oocysts was an important mode of transmission of T. gondii to women.     

Glycoprofiling of the Human Salivary Proteome

Introduction  Glycosylation is an important component for a number of biological processes and is perhaps the most abundant and complicated of the known post-translational modifications found on proteins. Methods  This work combines two-dimensional (2-D) polyacrylamide gel electrophoresis and lectin blotting to map the salivary glycome and mass spectrometry to identity the proteins that are associated with the glycome map. A panel of 15 lectins that recognize six sugar-specific categories was used to visualize the type and extent of glycosylation in saliva from two healthy male individuals. Lectin blots were compared to 2-D gels stained either with Sypro Ruby (protein stain) or Pro-Q Emerald 488 (glycoprotein stain). Results  Each lectin shows a distinct pattern, even those belonging to the same sugar-specific category. In addition, the glycosylation profiles generated from the lectin blots show that most salivary proteins are glycosylated and that the profiles are more widespread than is demonstrated by the glycoprotein-stained gel. Finally, the coreactivity between lectins was measured to determine what types of glycan structures are associated with one another and also the population variation of the lectin reactivity for 66 individuals were reported. Conclusions  This starting 2-D gel glycosylation reference map shows that the scientifically accepted, individual oligosaccharide variability is not limited to a few large glycoproteins such as MUC5B, but are found on most members of the salivary proteome. Finally, in order to see the full range of oligosaccharide distribution, multiple reagents or lectins are needed. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Cell surface glycoproteins of CHO cells. I. Internalization and rapid recycling

The major cell surface proteins of Chinese hamster ovary (CHO) cells have been investigated after reacting cells at 4 degrees C with the membrane-impermeant reagent, trinitrobenzenesulfonate (TNBS). Immunoprecipitation and subsequent two-dimensional, sodium-dodecyl sulfate, polyacrylamide gel electrophoresis (SDS-PAGE) of proteins from derivatized cells that had been labelled previously with [3H]D-glucosamine or [3H]L-leucine showed that TNBS reacted with most of the high molecular weight (HMW) acidic glycoproteins that became labelled with iodine by the lactoperoxidase technique and that bind the lectin, wheat germ agglutinin (WGA). After warming the cells to allow endocytosis to proceed, molecules haptenized with trinitrophenol (TNP) groups were followed radiochemically by means of [125I]anti-DNP antibodies. The half-life for internalization of proteins tagged with either [125I]anti-DNP IgG or Fab averaged about 5 min. A similar result was obtained when a monoclonal antibody directed against a single plasma membrane glycoprotein was used, or when the rate of surface loss of TNP groups unoccupied by antibodies was measured. Within 15 min at 37 degrees C, a steady-state between surface and cytoplasmic label was reached, with about 65% of the hapten located internally. Recycling of internalized TNP groups back to the cell surface also occurred rapidly (t 1/2 approximately 5 min). Most of the intracellular radioactivity was associated with a membrane fraction of density similar to that of the plasma membrane. Over a 4-h period, there was no significant entry of labeled molecules into lysosomes. By contrast, the fluid-phase marker, horseradish peroxidase, became associated with the lysosomes within 1 h. Our results are consistent with the view that the majority of plasma membrane glycoproteins are continuously being internalized and recycled at a high rate.