No abstract

The lectin of Dolichos biflorus, a hemagglutinin previously considered to be blood group A specific, is now found to react much more strongly with the terminal disaccharide unit [alpha DGalNAc(1 leads to 3) beta DGalNAc] of the Forssman antigenic determinant. In contrast, the relative reactions of the lectins of Helix pomatia (which also agglutinates A erythrocytes) and Wistaria floribunda (which agglutinates A, B, and O erythrocytes) with the Forssman pentasaccharide were substantially weaker than that of Dolichos biflorus. The combining site of the lectin of Helix pomatia has a broader affinity for terminal 2-acetamido-2-deoxy-alpha-D-galactopyranose (alpha DGalNAc) residues than does that of Dolichos biflorus. The reactions of the lectin with terminal alpha DGalNAc units are strongly dependent on the nature of the aglycon and remain ill defined. The lectin may also react with appropriately presented terminal 2-acetamido-2-deoxy-beta-D-glucopyranose units. The broad affinity of the lectin of Wistaria floribunda which reacts both with a range of blood group specific glycoproteins (A, B, H, Lea, and Leb) and with non blood group glycoproteins [Sugii, S., & Kabat, E.A. (1980) Biochemistry 19, 1192-1199] appears best assigned to a combining site that favors pauci- or multivalent cooperative effects of clustered terminal beta-D-galactopyranose units. An attempt is made to rationalize certain of the inhibition data in terms of topographical features at the surfaces of the carbohydrate structures which are considered compatible for binding within essentially hydrophobic combining sites.

High-titer antisera specific for the Lewis-a, -b, and -d determinants were obtained by the immunization of rabbits with artificial antigens prepared by coupling chemically synthesized haptens to bovine serum albumin. The use of the appropriate synthetic immunoadsorbents allowed the isolation of the desired antibodies from the sera and the elimination of cross-reactive antibody populations. The resulting refined antibodies proved highly effective for the localization by immunofluorescence staining of Lewis antigens in epithelial cells of gastric and duodenal tissue of H patients. Furthermore, the immunohistochemical procedures could be performed in conventionally prepared paraffin tissue sections. In erythrocyte Lewis-a and -b individuals, the strongest staining reactions were with the appropriate reagent. Lewis-a individuals were Lewis-d negative. Tissue from Lewis-a--b--secretors showed strong positivity in the epithelial cells of the stomach only with the Lewis-d reagent while none of the reagents showed strong reactions with the tissue from the one nonsecretor Lewis-a--b--patient. The significance of these results to the biogenesis of the Lewis antigens is discussed.

A piezopolymer pressure sensor has been developed for service in a portable fetal heart rate monitor, which will permit an expectant mother to perform the fetal nonstress test, a standard predelivery test, in her home. Several sensors are mounted in an array on a belt worn by the mother. The sensor design conforms to the distinctive features of the fetal heart tone, namely, the acoustic signature, frequency spectrum, signal amplitude, and localization. The components of a sensor serve to fulfill five functions: signal detection, acceleration cancellation, acoustical isolation, electrical shielding, and electrical isolation of the mother. A theoretical analysis of the sensor response yields a numerical value for the sensor sensitivity, which is compared to experiment in an in vitro sensor calibration. Finally, an in vivo test on patients within the last six weeks of term reveals that nonstress test recordings from the acoustic monitor compare well with those obtained from conventional ultrasound.

Seven different granulocyte-reactive murine monoclonal antibodies (mAb) were studied. The antigens recognized by these mAb were immunoprecipitated from lysates of 125I-labeled granulocytes of healthy donors. The isolated antigens were analyzed by electrophoresis on sodium dodecyl sulfate-polyacrylamide gel and autoradiography. All 7 antibodies precipitated the same 6 membrane polypeptides from membrane-iodinated granulocyte lysates: 105 and 150-kDa as most pronounced, together with 260-, 230-, 67- and 52-kDa polypeptides. One of the antibodies studied, B4.3, is directed against 3-alpha-fucosyl-N-acetyllactosamine as shown by absorption with the synthesized carbohydrate molecule. Competition experiments with 125I-labeled B4.3 demonstrated complete inhibition of binding by B4.3 and 3 of the other antibodies (VM D5, UJ308, MI/N1) and partial inhibition by the 3 other antibodies (FMC 10, FMC 12, FMC 13), indicating binding to the same antigenic structure. None of the 7 mAb reacted with monocytes in the immunofluorescence technique, but after neuraminidase treatment of these cells, positive reactions were obtained with all mAb. Immunoprecipitation with lysates of both native and neuraminidase-treated monocytes showed no polypeptide bands. Monocytic differentiation of the cell line HL60 by 12-O-tetradecanoylphorbol-13-acetate (TPA) and of cell line U 937 by dimethylsulfoxide and TPA was accompanied by a decrease in reactivity with these antibodies, which could be recovered by neuraminidase treatment. This indicates that 3-alpha-fucosyl-N-acetyllactosamine is masked for the detection of the antibody upon monocytic differentiation by sialylation.