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Biomedical subjects

B Diamond

Publications and source records attributed to B Diamond.

At least 163 records · Page 9Linked to original sources
PubMed1980

IgG1 and IgG2b share the Fc receptor on mouse macrophages.

Monoclonal IgG1 anti-SRBC has been used to study the binding of monomeric and aggregated IgG1 to Fc receptors on mouse macrophages. Aggregated IgG1 was found to bind to Fc receptors on two macrophage cell lines and on primary macrophages. It competes for binding with IgG2b and not IgG2a. Like the binding of IgG2b, the binding of IgG1 is unaltered at 4 degrees C and is insensitive to trypsin or cytochalasin B. Antigen-bound IgG1, like IgG2b and IgG2a, mediates phagocytosis. Variant macrophage cell lines selected for the loss of phagocytosis through the IgG2b receptor no longer phagocytize IgG1 bearing SRBC. Monomeric IgG1 did not bind to either macrophage lines or primary macrophages. We conclude from these experiments that antigen-activated IgG1 binds to the same receptor as IgG2b.

Animals↗
PubMed1980

All classes of murine IgG antibody mediate macrophage phagocytosis and lysis of erythrocytes.

Antibody-dependent phagocytosis and lysis of sheep RBC by mouse peritoneal exudate cells were studied using IgG subclass fractions of sera prepared by protein A-Sepharose chromatography. Three IgG1, 3 IgG2a, 4 IgG2b, and 1 IgG3 hybridoma antibodies to RBC were also used. The results showed that some monoclonal IgG2a and IgG2b antibodies were more active than IgG1 or IgG3 preparations when normalized to hemagglutinating activity, but all IgG sources mediated both effector mechanisms. This is in accord with findings of strong Fc receptors on macrophages for the IgG2 isotypes and weaker binding by IgG1 and newly discovered IgG3 receptors. A monoclonal IgG2b with no hemagglutination titer showed normal cooperation with macrophages. In contrast, 2 hybridoma IgM were inactive in macrophage-mediated lysis and allowed only marginal ingestion. Similar results were obtained using several macrophage cell lines, mouse spleen and human peripheral blood mononuclear cells, showing that all these types of effector cells do not distinguish among (mouse) IgG subclasses in handling antibody-coated RBC.

Animals↗
PubMed1979

Site of binding of mouse IgG2b to the Fc receptor on mouse macrophages.

Three mouse immunoglobulins with altered heavy chains have been used to study the specificity of the mouse IgG2b Fc receptor on mouse macrophages. These immunoglobulins were synthesized by variant clones derived from the MPC 11, IgG2b-producing mouse myeloma cell line. One variant, whose Fc receptor. A second variant, which makes a short heavy chain lacking the CH3 domain, binds specifically to the IgG2b Fc receptor. The third variant makes a hybrid IgG2b-IgG2a heavy chain whose CH3 domain is enterely IgG2a-like and binds to both IgG2a and IgG2b Fc receptors. These data suggest that the binding of mouse IgG2b immunoglobulins to the mouse macrophage Fc receptor involves a site within the CH2 domain and indicate that immunoglobulins with altered heavy chains are a useful tool to probe Fc receptors.

Animals↗
PubMed1977

Heart rate and cardiac phase influences on visual perception.

Twenty-six subjects were tested with a tachistoscopic recognition task while heart rate and several other autonomic indexes were monitored. In Experiment 1, heart rate was employed as an independent variable, and stimulus presentation was contingent upon the presence of individually determined low, middle, and high heart rates. The results indicated that low heart rate facilitated performance especially for stimuli presented at the fastest exposure. In Experiment 2, stimulus presentation was dependent upon cardiac phase. The findings indicated that stimulus recognition was enhanced during the cardiac P wave, but the effect was apparent only during the fastest exposure. Multiple regression analyses of the individual subject's data during both experiments indicated that highly idiosyncratic patterns of physiological responses predicted perceptual performance. The results were interpreted as being consistent with the formulations of the Laceys and also suggested that cerebral perfusion be considered as a relevant determinant of behavior.

Adult↗