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Biomedical subjects

B Enders

Publications and source records attributed to B Enders.

At least 37 records · Page 2Linked to original sources
PubMed1986

Toxicity of "hydrophobic groupings" and the role of carbohydrates in Plasmodium falciparum infection.

We have tested various carbohydrate structures and neoglycoproteins (carbohydrate haptens attached to BSA) as inhibitors of the invasion of human red blood cells by Plasmodium falciparum merozoites (strain FCB) in synchronous in vitro cultures, using 3H-hypoxanthine incorporation into intraerythrocytic parasites as analytical tool, and have got the following results: The inhibition rate of N-acetyl-D-glucosamine glycosides is increased with increasing lipophilicity of the aglycon or spacer: CH3 less than (CH2)2NHCO(CH2)2COOCH3 less than (CH2)8COOCH3; p-Nitrophenyl glycosides proved to exhibit a toxic effect; The inhibition rate of synthetic disaccharide glycosides increased in the order beta DGal(1----4) beta DGlcNAcOCH3 less than beta DGlcNAc(1----4) beta DGlcNAcOCH3 less than beta DGlcNAc(1----4) alpha DManOCH3 less than beta DGlcNAc(1----4) beta DManO(CH2)8COOCH3; The O-linked tetrasaccharide alpha NeuAc(2----3) beta DGal(1----3) [alpha NeuAc(2----6)] alpha DGalNAcol, isolated from glycophorin A, was the best carbohydrate inhibitor tested so far; The inhibition rate of carbohydrates attached to BSA by an aliphatic spacer [-(CH2)8COOCH3] was not enhanced compared to the haptens; [DNP]33-BSA proved to be an extraordinary inhibitor of invasion which, however, most likely has to be attributed to a toxic effect; Observed toxicities appear to be attributable to hydrophobic interactions between the inhibitors and the RBC and merozoite membranes, which hampers both, intraerythrocytic growth of the parasite and its capability of RBC invasion.

Animals↗
PubMed1984

Plasmodium falciparum: carbohydrates as receptor sites of invasion.

Monosaccharides, disaccharides, and trisaccharides were tested as inhibitors of the in vitro growth of Plasmodium falciparum (strain FCB). While certain monosaccharides (N-acetyl-D-glucosamine, D-mannose, and 3-O-methyl-D-glucose) proved to exhibit a toxic or reversibly retarding effect on the intraerythrocytic development of the parasite, the corresponding alpha- or beta-methylglycosides did not. Several methylglycosides, synthetic di- and tri-saccharides, and artificial blood group antigens were further tested for inhibitory effects on invasion of host red blood cells in vitro. The synthetic disaccharides beta DGlcNAc(1----4) alpha DManOMe and beta DGlcNAc(1----4) DGlcNAc (chitobiose) were good inhibitors of invasion at 10 mM concentration, whereas beta DGal(1----4)beta DGlcNAcOMe was negligibly inhibitory. The inhibition rate of N-acetyl-D-glucosamine, beta-glycosidically linked to bovine serum albumin (BSA) by an alipathic spacer, -(CH2)8CO-, was not enhanced, compared to the corresponding hapten, beta DGlcNAcO(CH2)8COOCH3. The inhibition rates of blood group A- and B-trisaccharide haptens, which were inhibitors of invasion, were also not significantly enhanced when coupled to BSA by way of the corresponding amide spacer, -(CH2)2NHCO(CH2)7CO-. A remarkable enhancement of the inhibition rate was, however, observed when beta DGal(1----3) alpha DGalNAcO(CH2)2NHCO(CH2)7COOCH3 (T-hapten) was coupled to BSA. A clear-cut decrease in the inhibition rates of different beta-glycosides of N-acetyl-D-glucosamine, beta DGlcNAcOR, was observed, depending on the nature of the aglycon R(p-nitrophenyl greater than -(CH2)8COOCH3 greater than -(CH2)2NHCO(CH2)2COOCH3 greater than -CH3). Also, p-nitrophenyl-alpha-D-glucopyranoside was a much better inhibitor of invasion than the corresponding methyl glycoside, alpha DGlcOMe, which was not inhibitory. The properties of the aglycon spacer, used for the covalent attachment of the carbohydrate to the carrier protein, may thus be crucial for the outcome of the inhibition rate.

Animals↗
PubMed1984

Erythrocyte invasion by malaria (Plasmodium falciparum) merozoites: recent advances in the evaluation of receptor sites.

Recent advances in the understanding of the cellular, biochemical and molecular aspects of the highly specific interactions between P. falciparum merozoites and human red blood cells are summarized. Special attention is given to glycophorins A, B and C as receptors of invasion and to the role of carbohydrates and internal domains of glycophorin A, such as the Wrb antigen, as receptor site. Video pictures displaying the liberation of merozoites from schizont-infected red blood cells and the invasion of human erythrocytes by P. falciparum merozoites are also provided.

Animals↗
PubMed1983

Dual expression of T and B cell markers in human B cell neoplasias.

Macrophage- and T-cell-depleted mononuclear cells from 36 patients with B cell lymphoma and 12 healthy individuals were investigated by indirect immunofluorescence with the monoclonal antibodies NEI-011 (7.2) and NEI-015 (10.2). The monoclonal antibody NEI-011 (7.2) recognized the Ia antigen and identified almost all B cells in the peripheral blood of healthy individuals. Furthermore, neoplastic B cells from all patients except those with plasma cell proliferation were found to react with this antibody. NEI-015 (10.2), a monoclonal antibody known to react with both T cells and B-CLL cells, did not react with normal circulating B cells. However, this antibody did identify neoplastic B cells except in cases of plasma cell proliferation and lymphoblastic lymphoma.

Antibodies, Monoclonal↗
PubMed1983

Further evidence for T cell abnormalities in chronic lymphocytic leukaemia of the B cell type.

Functional properties were studied in the purified T cell fraction of patients with chronic lymphocytic leukaemia of the B cell type (B-CLL). This analysis included the evaluation of T suppressor activity when investigated patients' T cells were co-cultured together with allogenic normal B and OKT4 enriched T cells in the presence of pokeweed mitogen (PWM). The Ig secreting cells (ISC) were assessed in a reverse haemolytic plaque assay (RHPA). Antibody-dependent cytotoxicity (ADCC) and natural killer activity (NK) were determined in a 51Cr release assay. Furthermore, purified T cells reactive with the monoclonal antibody HNK1, known to recognize most effector cells in ADCC and NK, were enumerated using an indirect immunofluorescence. Our results revealed increased T suppressor cell activity and markedly deficient NK activity in peripheral blood lymphocytes (PBL), T cell and T gamma cell fractions from B-CLL patients, whereas ADCC potential was only increased in T cells and T gamma cells. Accordingly, T cells were recognized by HNK1 in greater numbers in B-CLL patients than in healthy subjects. Our data suggest that there may be a link between our findings and the hypogammaglobulinaemia as well as the increased incidence of second neoplasias reported in CLL.

Aged↗
PubMed1982

B-cell function in patients with chronic lymphocytic leukemia.

Using a reverse hemolytic protein A plaque assay, spontaneous and pokeweed mitogen (PWM)-induced immunoglobulin (Ig) secretion was determined in peripheral blood from 22 patients with B1-chronic lymphocytic leukemia (CLL), one patient with B2-CLL, and one patient with suppressor T-CLL. Diagnoses were established by cytological and histological criteria as well as several marker analyses. Lymphocytes from B1- and B2-CLL patients were unable to secrete Ig either spontaneously or after PWM stimulation. In T-CLL lymphocytes, spontaneous Ig secretion was suppressed very probably by the OKT-8-positive leukemic population, since, after cultivation with PWM, a normal Ig secretion could be demonstrated which was paralleled by a decrease in the OKT-8-positive cells. Cocultivation experiments with freshly isolated, unseparated lymphocytes from normal subjects and lymphocytes from patients were of no informational value, since isolated normal B-cells alone already showed a high rate of Ig secretion. However, coculture experiments with separated subpopulations after PWM stimulation revealed an intrinsic B-cell defect in lymphocytes from B1-CLL patients, whereas their T-lymphocytes were found to be normal helper cells.

Adult↗
PubMed1981

PWM-induced generation of immunoglobulin-secreting cells in patients with multiple myeloma.

The pokeweed-mitogen-induced transformation of B-lymphocytes into immunoglobulin-secreting cells was studied in vitro in 25 patients with multiple myeloma using a reverse hemolytic plaque assay. Fifteen patients showed a good response in generating immunoglobulin-secreting cells, whereas 10 patients showed a decreased B cell reactivity which was not due to intermittent melphalan/steroid therapy administered to 15 patients. Experiments with lymphocyte subpopulations demonstrated that the inability of some multiple-myeloma patients to generate immunoglobulin-secreting cells was always based on a defect in the B-cell subset. Co-culture experiments with lymphocytes from normal individuals and patients revealed a cell-mediated suppression in one case, whereas humoral suppressive factors in the patients' serum could not be observed using the reverse hemolytic plaque assay. Patients were classified into three groups: (a) patients with a normal B-cell function, (b) patients with a reversible, tumor-dependent suppression of B-cell reactivity and (c) patients in whom the normal B-cell population was replaced by non-reactive cells.

Adult↗
PubMed1981

Impaired B-lymphocyte reactivity in patients with Hodgkin's disease and non-Hodgkin-lymphomas.

The generation of immunoglobulin-secreting cells upon stimulation with pokeweed mitogen was studied in patients with Hodgkin's Disease (HD) and non-Hodgkin lymphomas (NHL) using a reverse hemolytic plaque assay. The experiments revealed that the majority of the patients in both groups had greatly diminished responses of their peripheral B-lymphocytes. Whereas in NHL patients an intrinsic B-cell defect is the most likely explanation for the impaired B-cell reactivity, the situation in HD appears to be more complex. In some patients with an active stage of the disease, suppressor cells were found to cause the unresponsiveness: in other patients, an intrinsic B-cell defect as well as a defect of the T helper cells were responsible for the diminished responses. The results further suggest that the immune defect in patients with HD is reversible and can be corrected by therapy.

Adolescent↗
PubMed1980

Characteristics of immunoglobulin secretion in man evaluated by a reverse hemolytic plaque assay.

The kinetics of Pokeweed mitogen-induced transformation of human B-lymphocytes into immunoglobulin-secreting cells were examined in a reverse hemolytic plaque assay using protein A-coated sheep red blood cells as indicator cells. Peak responses occurred consistently after 6-8 days of incubation. After determination of the optimal experimental conditions the RHPA was found to be a reliable tool to estimate ISC in vitro; the technique was also found to be applicable for experiments surveying the B-cell response of an individual over a period of months. The PWM-induced transformation of B cells was absolutely T-cell-dependent. Other substances known as typical T-cell mitogens were also tested for polyclonal B-cell activation and some of them showed significant responses. Further experiments have shown that co-cultivation of non-HLA identical cells did not increase the number of plaques in unstimulated cultures whereas the addition of PWM leads to the generation of ISC within the expected range. These findings open a wide field of application of the RHPA in experimental and clinical immunology.

Animals↗
PubMed1977

Biochemical and technical considerations regarding the mass production of certain parasitic protozoa.

This article summarizes the most relevant biochemical knowledge about growth factors as specific essential components of culture media, and calls attention to their significance with respect to the mass cultivation of some parasitic protozoa-e.g., Trypanosoma and Leishmania spp. and amoebae. Details of recent developments and techniques of parasite fermentation are reviewed.

Amino Acids↗
PubMed1976

Use of indirect microhemagglutination test with stable sensitized red cells in the detection of horse protein allergy.

Sheep red blood cells were stabilized with sulfosalicylic acid and sensitized with purified horse-IgG by the action of glutardialdehyde. The cells were used in an indirect microhemmagglutination test with serum samples from 12 rabbits immunized with horse-IgG and complete Freund's adjuvant as well as from 10 control animals. 32 human serum samples were examined, 6 of them from patients with established horse protein allergy. The results were compared to those of a standard method of indirect hemagglutination using fresh human erythrocytes (group O Rh-), an active hemagglutination test against horse erythrocytes, Ouchterlony's immunodiffusion and skin tests with horse-IgG. The method proved to be very sensitive. The results correlated well with those of the other immunological techniques. The stable sensitized cells did not lose sensitivity after 1 year of storage at 4 degrees C.

Animals↗
PubMed1975

Survey on experiences with latex-Chagas-test in various countries.

The principle of the latex agglutination technique was applied on the serodiagnosis of Chagas' disease. The latex particles coated with antigen from Trypanosoma cruzi are agglutinated by antibodies against T. cruzi in the serum of patients suffering thereof. In 11600 comparative determinations worked out mainly in a number of South American laboratories, the sensitivity of this test was compared with xenodiagnosis, CF, IFT and IHA. The latex Chagas test shows a mean coincidence of 90% with xenodiagnosis, 88% with CF, 75% with IFT, and 83% with IHA. The results indicate that the test is a useful new tool for the serodiagnosis of Chagas' disease. Also the data from CF, IFT and IHA were compared with each other. The latex Chagas test is sensitive even in the early stage of the disease. Also the specificity of the test was evaluated in other parasitic, bacterial and general diseases.

Animals↗