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Biomedical subjects

E L Romano

Publications and source records attributed to E L Romano.

9 recordsLinked to original sources
PubMed1992

A modified colorimetric method for the measurement of phagocytosis and antibody-dependent cell cytotoxicity using 2,7-diaminofluorene.

A sensitive and rapid colorimetric method for the in vitro determination of phagocytic activity and antibody-dependent cell-mediated cytotoxicity (ADCC) is described. The assay uses red blood cells (RBC) as target cells and relies on the specific oxidation of 2,7-diaminofluorene (DAF) by the pseudoperoxidase activity of hemoglobin (Hb). Generation of fluorene blue (FB), the chromophore formed upon oxidation of DAF, was a linear function of erythrocyte concentration. The oxidation of DAF by peritoneal macrophages (M phi) containing myeloperoxidase was negligible, confirming that the development of color was exclusively due to the pseudoperoxidase activity of Hb. A positive correlation was observed between FB formation and increased phagocytosis of opsonized erythrocytes. Phagocytosis increased as a function of time, reaching a maximum at 90 min of incubation. The phagocytosis of IgG-opsonized erythrocytes was greater than non-opsonized erythrocytes and was inhibited by high concentrations of non-specific human or mouse IgG, showing that phagocytosis was mediated by the Fc gamma receptor of macrophages. The interaction between opsonized RBC and macrophages also evoked an antibody-dependent extracellular lysis, however this process was slower than ingestion. The DAF phagocytosis assay has shown to be very sensitive, simple, rapid and safe.

Animals↗
PubMed1992

Enzyme-linked immunosorbent assay for the detection of substances that carry blood group A specificity.

An enzyme-linked immunosorbent assay (ELISA) was developed to estimate the amount of material carrying blood group A activity in biologic samples. A soluble synthetic form of the A antigenic determinant (A trisaccharide, ATS) conjugated to peroxidase competes with the blood group A substance present in a biologic sample for anti-A attached to a solid phase by a second antibody coating the plastic micro-wells. A reference curve is constructed by using known quantities of ATS to compete with a fixed amount of ATS-peroxidase conjugate. The A substance activity in a sample is obtained by extrapolating the degree of inhibition of the binding of the ATS-peroxidase conjugate to an equivalent amount of ATS in the reference curve. The assay is reproducible, specific, and sensitive. It has been used in pharmacologic studies to estimate the concentration of ATS in the blood and urine of rats, rabbits, and baboons and in a study with human samples, testing the potential clinical use of ATS to neutralize anti-A when therapeutically indicated. It is also useful for the detection of ABO natural products in secretions, thus allowing the accurate classification of secretor and nonsecretor individuals.

ABO Blood-Group System↗
PubMed1979

Fe(III)-EDTA complex as iron fortification. Further studies.

The data presented confirm the advantages of Fe(III)-EDTA as a salt for iron fortification. This iron compound exchanges completely with intrinsic wheat iron in the lumen of the gut. The iron absorption data from this salt tested with six different food vehicles compared with the absorption of ferrous sulfate administered with the same vehicles indicate that while the mean absorption from ferrous sulfate varies from 2 to 30% according to the food vehicle mixed with the salt, the absorption from Fe(III)-EDTA remains practically the same. Apparently, the iron absorption from Fe(III)-EDTA complex is slightly or not affected by the presence of vegetable foods or milk. All these data suggest that only a small amount of iron from this salt, about 10 mg/day, would be necessary to prevent iron deficiency anemia even in those populations relying for their subsistence on vegetable food only.

Absorption↗
PubMed1978

Number of B sites generated on group O red cells from adults and newborn infants.

When red cells from the group O blood of adults and newborn infants (cord blood) were incubated with UDP-galactose and group B serum, over 200,000 B sites per cell were generated on adult O cells but only 40,000--70,000 sites per cell on cord cells. It is concluded that smaller amounts of substrate for the B transferase are present on cord cells.

ABO Blood-Group System↗
PubMed1976

Direct observation of immunoglobulins on the erythrocyte membrane.

A modification of the sublimation procedure for observation of cell membrane exteriors is described. By retaining basic advantages of the freeze-fracture technique, without actual fracturing of the sample, high quality replicas can be produced on which molecules such as immunoglobulins can be identified and mapped on extensive areas of the erythrocyte membrane surfaces. The method can be used for direct observation of antibodies without recourse to labelling with other marker molecules, such as for example ferritin. In addition, direct visualization of clumping of red cells, as induced by such antibodies, is feasible.

Cell Membrane↗
PubMed1975

Red cell destruction in vivo by low concentrations of IgG anti-A.

Red cells coated with as little as 0.3-0.5 mug anti-A/ML cells were found to agglutinate if mixed with plasma and rocked on a tile, whereas the minimum amount of IgG anti-Rh required for agglutination under these conditions was about 50 mug antibody/ml cells. Complement-binding by red cells coated with IgG anti-A could be demonstrated only when the amount of antibody on the cells was at least 14 mug antibody/ml cells. Since in ABO haemolytic disease the amount of antibody on the cells is frequently less than 0.6 mug/ml cells, it seems that red cell destruction in this syndrome is not due to the activation of complement but may be due to the sequestration of agglutinated cells. A few experiments are described in which the survival in vivo of small amounts of agglutinated cells was studied. Reasons are given for considering that such experiments fail to mimic the conditions prevailing in ABO haemolytic disease.

ABO Blood-Group System↗
PubMed1975

Distribution and mobility of the A, D and c antigens on human red cell membranes: studies with a gold-labelled antiglobulin reagent.

Studies are presented in which a gold-labelled anti-IgG reagent has been used to map the distribution of A, D and c antigen sites on the human red cell membrane. Red cells were combined with IgG antibodies; ghosts were produced which were then labelled with gold-anti-IgG. D antigen sites were found to be single entities dispersed on the red cell membrane of lysed but otherwise untreated Rh positive cells. Following papain treatment prior to lysis, a clustered distribution was observed. Clustering of D sites was also observed on non-enzyme-treated red cells of the -D- phenotype. Further studies indicated that D and c antigen sites are closely associated on ccDEE red cells. The distribution of A antigen sites was found to be clustered in proportion to the amount of IgG anti-A combined with the cells. Reasons are given for considering such distribution as indirect evidence of mobility of A sites. There was an association between agglutinability of red cells by IgG antibodies and the extent of the clustering of the antigen sites.

ABO Blood-Group System↗
PubMedDate not supplied

Complement fixation by Rh blood group antibodies.

Rh blood group antibodies normally do not fix complement. Rh positive intact red blood cells treated with papain do not lyse when incubated with corresponding antibody and complement. This study was done to determine if complement fixation occurs when antibodies were combined with Rh positive red blood cell ghosts untreated or treated with papain. Complement fixation was observed with IgG anti-D, anti-DC and anti-c when papain treated ghosts were used. No complement fixation or a smaller degree of it was observed in the case of untreated Rh positive red blood cell ghosts when incubated with similar anti-Rh antibodies. It is concluded that the papain treatment of Rh positive red blood cell ghosts, possibly by inducing aggregation of antigen sites, allowed complement binding by Rh antibodies.

Animals↗