Faculty Bibliography

The effects of furosemide and 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS) on steady-state Cl- flux were studied in Ehrlich mouse ascites cells. At 10 mM, furosemide inhibited isotopically-determined Cl- flux by 86% without changing cell Cl- content, indicating that influx and efflux were depressed by the same amount. These results suggest that at least 86% of the steady-state Cl- flux may occur as a one for one exchange. Half of the inhibitory effect was not reversed by vigorous washing with albumin-Ringer. A smaller portion of steady-state Cl- flux was inhibited by SITS. The maximum effect of SITS was reached near 0.6 mM; at this concentration Cl- flux was reduced by 37% without an alteration in cell Cl- content. Possible competition of environment Cl- and SITS was investigated by replacing environment Cl- with acetate or NO3. These anions reduced the efficacy of SITS because they depressed cell Cl- turnover themselves, apparently acting on the same exchange process

Several aspects of the interaction of various lectins with the surface of Ehrlich ascites carcinoma cells are described. The order of agglutinating activity for various lectins is Ricinus communis greater than wheat germ greater than or equal to concanavalin A greater than or equal to soybean greater than Limulus polyphemus. No agglutination was noted for Ulex europaeus. Using 125I-labeled lectins it was determined that there are 1.6 and 7 times as many Ricinus communis lectin binding sites for concanavalin A and soybean lectins. Sodium deoxycholate-solubilized plasma membrane material was subjected to lectin affinity chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The lectin receptors of the plasma membrane appeared to be heterogeneous and some qualitative differences could be discerned among the electrophoretically analyzed material, which bound to and was specifically eluted from the various lectin affinity columns. The characteristics of elution of bound material from individual lectin columns indicated secondary hydrophobic interactions between concanavalin A or wheat germ agglutinin and their respective lectin receptor molecules

Purified blood group-active substances derived from different pig, horse, baboon, Rhesus monkey and human tissues were quantitatively studied for their haemagglutination inhibiting potency with: (1) human IgM anti-A and anti-B; (2) human anti-Lea and anti-Leb; (3) Ulex europaeus extracts separated into lectin fractions with respective L-fucose-inhibitable ('anti-HF') and chitobiose-cellobiose-inhibitable ('anti-HC') combining sites. Irrespective of species origin, A and B blood group activity per milligram of purified material tended to be strikingly higher in substances low in, or devoid of, Lewis blood group activity. Most of the blood group substances displayed variable but about equally balanced amounts of Ulex anti-HF and anti-HC inhibiting activity. In contrast, pig submaxillary gland mucins displayed strikingly high levels of Ulex anti-HC inihibiting activity, even in the complete absence of Ulex anti-HF inhibiting activity. These serological findings are consistent with current biochemical concepts regarding the heterosaccharide microheterogeneity of blood group-active glycoproteins