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Biomedical subjects

P Aman

Publications and source records attributed to P Aman.

At least 127 records · Page 7Linked to original sources
PubMed1984

Phenotypic modulation of chronic lymphocytic leukemia cells by phorbol ester: induction of IgM secretion and changes in the expression of B cell-associated surface antigens.

Freshly explanted neoplastic populations from 22 cases of phenotypically well-characterized chronic type B lymphocytic leukemia were studied for their capacity to respond to the phorbol ester TPA in vitro. In all but four cases the secretion of IgM was either induced or increased, often to a high level. In contrast, the export of free immunoglobulin (Ig) light chains, an almost consistent feature of the B lymphocytic leukemias, remained relatively constant after TPA treatment. Parallel changes in leukemic cell surface phenotype were probed with both "conventional" and monoclonal antibodies, revealing some modulation of markers in every case investigated. A diminution in the level of surface Ig (preferentially IgD) and the accumulation of cytoplasmic Ig observed after phorbol ester treatment were accompanied by a corresponding reduction or loss of the B1 antigen and usually of B2 when present. The most consistent change induced by TPA was the appearance of BB-1, a marker of activated B lymphocytes, which was rarely expressed on fresh leukemic cells. Another marker of activated lymphocytes, LB-1, was also often induced or increased in its expression after exposure of the cells to TPA. The magnitude of the TPA response appeared to relate to the stage of maturation arrest of the individual leukemic clones rather than to any clinical parameter explored. The significance of the findings to normal B cell differentiation and their potential clinical utility are discussed.

Antigens, Neoplasm↗
PubMed1983

Relationship between the amounts of EBV-DNA and EBNA per cell, clonability and tumorigenicity in two ebv-negative lymphoma lines and their EBV-converted sublines.

The effect of EBV-conversion of two EBV-negative lymphoma lines (Ramos and BJAB) on agarose clonability and tumorigenicity in nude mice was explored. The cloning frequency was increased in all 9 sublines investigated, between 1.1 and 4.9 times compared to the original "parental" lines. Tumorigenicity was increased in one out of 2 BJAB-derived, EBV-positive lines and in 3 of 6 Ramos-derived lines, while it was decreased in 3 others. A strong positive correlation between the number of genomes/cell and the amount of EBNA/cell was detected, and in 7 of 9 converted lines the cloning frequency also correlated to the number of EBV genomes. On the other hand, no relation was established between the number of EBV-genomes/cell, the amount of EBNA/cell and tumorigenicity.

Animals↗
PubMed1983

Epstein-Barr virus (EBV)-induced lymphoproliferative disease in cotton-topped marmosets.

Six cotton-topped marmoset monkeys (Sangiunus oedipus) were inoculated with 10(5) transforming units of B95-8 virus, and two of them developed fatal lymphoproliferative disease. The EBV-carrying tumor cells from these marmosets had the following characteristics: (1) they were polyclonal by surface immunoglobulin and immunoglobulin production in vitro; (2) they had no specific chromosome abnormalities, and (3) they failed to form colonies in large percentages in agarose. It is proposed that a spectrum of phenotypes of EBV-induced lymphoproliferative diseases in the cotton-topped marmosets may be identified and are more akin to fatal infectious mononucleosis or X-linked lymphoproliferative syndrome than to Burkitt's lymphoma.

Animals↗
PubMed1983

In vitro differentiation of chronic lymphocytic leukaemia cells with a small pre-B-like phenotype.

Neoplastic populations from three cases of chronic lymphocytic leukaemia (CLL) which had features consistent with a maturation arrest at the 'small pre-B' stage are described. The cells were small and rounded with a scanty cytoplasm and stained for mu heavy chains but not light chains intracellularly while surface immunoglobulin (SmIg) was either undetectable or expressed sparsely on a minority of cells. Other features included the weak expression of B1, a lack of B2, an absence of the common acute lymphoblastic leukaemia antigen (cALLA), the presence of Ia and a variable expression of the receptors for Fc gamma and C3. Successful induction of in vitro differentiation in all three of the cases allowed the identification of a sequence of events whereby cells initially containing isolated mu heavy chains in their cytoplasm, on commencing light chain synthesis, begin to express stable SmIgM while surplus light chain is secreted without any association with the heavy chain. Although this is followed ultimately by the secretion of intact Ig effector molecules, the export of surplus light chains is apparently maintained throughout the developmental sequence. These findings are discussed with particular emphasis on their relation to normal B-cell maturation.

Aged↗
PubMed1983

Leu 7+ (HNK-1+) cells. II. Characterization of blood Leu 7+ cells with respect to immunophenotype and cell density.

In the present study, combined methods (indirect immunofluorescence with monoclonal antibodies, Percoll density fractionation, FACS analysis, and the cytotoxicity test) were used for further characterization of peripheral blood Leu 7+ cells (human NK and K cells). The Leu 7+ cell content was found to be relatively higher in the low-density cell fraction in which cells of large granular lymphocyte morphology predominated. However, Leu 7+ cells were also present in intermediate and high-density fractions. Low-density Leu 7+ cells were characterized by both Leu 2 (T suppressor/cytotoxic) and OKM1 (myelomonocytic) markers, whereas among high-density Leu 7+ cells the Leu 2 phenotype strictly predominated. Depletion of OKT3+ cells from the non-adherent cell population caused a decrease of cells with T helper and T suppressor phenotypes but did not have this effect on Leu 7+ and OKM1+ cells. After depletion of Leu 7+ cells from the OKT3- population the content of both T suppressor and OKM1+ cells decreased. Both the present results and previous reports enable us to conclude that two main Leu 7+ cell subpopulations are present in blood, namely Leu 7+Leu 2+/Leu 4+ and Leu 7+/OKM1+ cells. The presence of small and large Leu 7+ cells was also shown by FACS analysis.

Cell Separation↗
PubMed1983

Phenotypes in chronic B-lymphocytic leukemia probed by monoclonal antibodies and immunoglobulin secretion studies: identification of stages of maturation arrest and the relation to clinical findings.

Neoplastic populations from 25 cases of B-lymphocytic leukemia (B-LL) were investigated in an attempt to define the stages of maturation arrest represented in this disease and the relationship, if any, to various clinical parameters. Intrinsic to this study was the expression of a number of B-cell antigens defined by monoclonal antibodies. These included antibodies to B1 and B2, both expressed exclusively on B lymphocytes, but with the latter probably restricted to a narrow window of differentiation, BB-1 and LB-1, both markers of activated lymphocytes, and 38.13, a monoclonal antibody raised against and recognizing an epitope expressed on Burkitt lymphoma cells. While the patterns of reactivities were complex, the cases could be classified into various groups on the basis of the phenotypes revealed. These were termed "pre-B," "early-B," "intermediate-B," "mature-B," and "secretory-B" from their patterns of immunoglobulin (Ig) isotype expression and their capacity to secrete Ig in short-term culture. Although B1 was detected on neoplastic cells from all but one case, its intensity of expression varied markedly, being strongest on the "mature-B" and "secretory-B" cases and weakest on the "pre-B" type. The expression of B2 was essentially restricted to the "intermediate-B," "mature-B," and "secretory-B" cases and was usually, but not invariably, accompanied by the coexpression of surface IgM and IgD. While expression of BB-1 was restricted to a few cases with mature features, LB-1 was more frequently detected and found predominantly on "intermediate-B" and "mature-B" cases. The 38.13 antibody was found to react weakly with a number of the populations coexpressing IgM and IgD. The export of large amounts of whole Ig was restricted to three "secretory-B" cases all of which were associated with a serum M-component corresponding to the Ig isotype secreted in vitro. In contrast, the secretion of free Ig light chains was a consistent feature of all B-LL, and the amounts detected did not vary considerably between the different types. No correlation between immunologic cell-type and the stage of the disease was apparent. Classification of the cases into "true" B-chronic lymphocytic leukemia and immunocytoma similarly revealed no strict association of these histopathologic entities with any particular phenotypic group, although those cases with the more mature features tended to be immunocytomas. The findings are discussed within the context of normal B-cell differentiation pathways.

Antibodies, Monoclonal↗
PubMed1982

Truncated mu chain in a Burkitt lymphoma line (P3HR-1) and its fate in various hemapoietic somatic cell hybrids.

Hybrids obtained by the fusion of PUT, an ouabain and TG-resistant subline of the Burkitt lymphoma(BL)-derived P3HR-1 line, with hemopoietic cells of various differentiation types were tested for their membrane and intracellular immunoglobulin expression. PUT cells carry no membrane immunoglobulin, but contained intracellular 61K mu chain and kappa chain. The PUTKO-1 hybrid, derived from the fusion of PUT with the erythroleukemia line K562 contains no detectable immunoglobulin. NAMPUT, a hybrid between PUT and the IgM-lambda-producing BL line Namalwa, synthetizes cellular mu, lambda and kappa chains, but its surface-Ig is exclusively mu-lambda. Two different mu chains could be detected, both precipitated by either anti-mu or anti-lambda sera. Immunoprecipitation with anti-kappa precipitated neither kappa nor mu. PUTRAL was derived by fusing PUT with Rael, an unusual surface-IgG-lambda-carrying BL line. In this hybrid, the ability to synthesize gamma and lambda chains has been eclipsed, but two mu chains are present: one corresponding to the truncated 61K chain of PUT, and a normal-sized 74K. Between 20 and 30% of the cells stain for surface IgM.

Autoradiography↗
PubMed1982

Immune deficiency in the X-linked lymphoproliferative syndrome. II. Immunoregulatory T cell defects.

Surface phenotypic markers and the function of lymphocytes in patients affected with the X-linked lymphoproliferative syndrome (XLP) were studied. This syndrome is characterized by a defective response to infection with Epstein Barr virus (EBV). Normal numbers of B and T cells were detected with anti-Ig and monoclonal OKT3 antisera, respectively. T cell subset values, however, were persistently altered: cells reacting with OKT8 were significantly elevated in five of nine patients, accompanied by a slight decrease in the percentage of OKT4-positive cells, leading to abnormally low OKT4 to OKT8 ratios. One patient had a high OKT4 to OKT8 ratio due to low number of OKT8-positive cells. Lymphocytes from patients showed normal proliferation after stimulation with T and B cell mitogens. In contrast, Ig synthesis by lymphocytes after stimulation with B cell mitogens was markedly deficient: low or undetectable levels of one or all classes of Ig were detected, whereas cell lines established from EBV-infected B lymphocytes from patients produced normal quantities of Ig. These studies imply immune regulatory impairments in the patient with XLP.

Antibodies, Monoclonal↗
PubMed1981

Membrane-bound and cellular immunoglobulins in human B-lymphoma lines and derived hybrids.

Hybrids derived from the fusion of cell lines representing different maturation stages were studied for their membrane and cellular immunoglobulin expression. The hybrids can be subdivided into 3 groups, with one common parental line in each group. In the first group, Raji cells represent the common parent: it contains small amounts of membrane and cytoplasmic mu (mu) and kappa (kappa) chains. In the second group, PUT is the common parent, an ouabain and TG-resistant subline of the BL-derived P3HR-1 line. PUT contains a truncated intracellular mu chain. The third group consists of hybrids between K562, an EBV-negative human erythroleukemia line and 2 different BL lines. Membrane-immunoglobulin expression was intermediate between the parental lines in the first two groups derived from the fusion of 2 BL lines. In the third group, hybridization with the K562 cell suppressed the membrane-Ig expression of the B-cell partner. Total cellular immunoglobulin determinations showed that some cells synthesized light chains in excess of heavy chains, others contained an excess of heavy chains, while still others had equal amounts of heavy and light chains. The hybrids showed a variety of patterns, including amplification of the parental phenotypes, appearance of new phenotypic combinations, and eclipse of one or both parental phenotypes. A comparison of the total and the membrane-associated immunoglobulin patterns suggests independent handling of intracellular and membrane immunoglobulin synthesis.

B-Lymphocytes↗
PubMed1981

Host-Symbiont Interactions : V. THE STRUCTURE OF ACIDIC EXTRACELLULAR POLYSACCHARIDES SECRETED BY RHIZOBIUM LEGUMINOSARUM AND RHIZOBIUM TRIFOLII.

The sequence of the glycosyl residues and the anomeric configurations of the glycosyl linkages of the acidic polysaccharides secreted by Rhizobium leguminosarum 128c53, Rhizobium leguminosarum 128c63, Rhizobium trifolii NA30, and Rhizobium trifolii 0403 have been determined. All four polysaccharides were found to have the following glycosyl repeating-unit structure, where galactosyl is Gal, glucosyl is Glc, glucuronosyl is GlcA, and pyruvyl is Pyr: [Formula: see text] Each of the glycosyl residues of these polysaccharides was determined to be in the d configuration and in the pyranose ring form. These results add support to the proposal that R. leguminosarum and R. trifolii have a particularly close genetic relationship. The significance of these results with regard to the possible function of these polysaccharides in the nodulation process is discussed.

Journal Article↗
PubMed1981

Cell-surface immunoglobulin and insulin receptor expression in an EBV-negative lymphoma cell line and its EBV-converted sublines.

Membrane Ig and insulin receptors were assayed in the EBV-negative Ramos lymphoma line and its EBV-converted sublines by surface fluorescence. 125I-protein A-binding assay, immunoprecipitation, and insulin receptor assay. The original Ramos line expressed surface IgM but not IgD and had a low concentration of insulin receptors. Ten of 10 converted lines expressed IgD and a variable but usually high insulin-binding capacity. Molecular weight analysis of immunoprecipitated Ig showed the presence of 2 mu-chains and 2 delta-chains. One of each heavy chain type could be characterized as membrane Ig, whereas the other was cytoplasmic. Antisera against the lambda-chain precipitated mu and delta heavy chains as well, indicating that the delta-chain expressed on the membrane of the EBV-converted Ramos lines is bound to the lambda light chain. The results show that the differentiation of a Burkitt lymphoma line is not completely "frozen" and can be induced to change in a more "activated" direction by EBV conversion.

Binding Sites↗
PubMed1979

Agarose isoelectric focusing of native human immunoglobulin M and alpha 2-macroglobulin.

The resolution of native 19S IgM and alpha 2-macroglobulin by agarose isoelectric focusing is described. The agarose used was practically charge free, thus avoiding disadvantages of electroendoosmosis, and gives a very large network gel, with minimal molecular sieving effects. The resolving power is comparable to that obtained in thin-layer isoelectric focusing in polyacrylamide gel. Clones of human IgM showed a microclonal heterogeneity, similar to IgG antibody heterogeneity, alpha 2-macroglobulin gave a pattern of seven bands in the pI range of 4.1 to 4.9. The flexibility of the agarose isoelectric focusing (IEF) system with regard to immunodetection techniques is illustrated by the use of immunofixation and two-dimensional crossed immunoelectrofocusing. The agarose IEF method has several advantages, viz., non-toxicity, simple handling, uniform and rapid gel formation, and considerably shortened fixing and staining times. The value of the new method is discussed, in particular its usefulness in detecting and isolating IgM antibodies of known specificity produced by cells in culture.

Humans↗
PubMed1977

1H-N.M.R., 13C-N.M.R., and mass spectra of glucosinolates and related compounds.

The mass spectra of per(trimethylsilyl) ethers of desulfated glucosinolates are dominated by ions derived from the glucose moiety. The ions at m/e 271 and 361 are much more abundant than in the spectra shown by the corresponding derivatives of hexoses and their simple glycosides. The individual glucosinolates are distinguished by a few ions originating from their respective aglycon groups. The 1H- and 13C-n.m.r. spectra of sinigrin and some closely related compounds have been analyzed.

Glucose↗
PubMedDate not supplied

NRAS mutations are rare in acute myeloid leukaemias with t(8;21) or inv(16).

Using PCR and direct sequence methodology, 19 haematologic malignancies with trisomy 8, 18 with t(8;21)(q22;q22) and 8 with inv(16)(p13q22) were screened for NRAS mutations. Of the 45 samples analyzed, 4 (9%) had a mutation; both wild-type and mutated alleles were observed in these 4 cases. Three of the mutations (involving codons 12 and 13) were found in the trisomy 8 group and 1 (codon 61) among the inv(16) samples. No specific clinical similarities were found in the 3 patients with +8 and NRAS mutation. By analyzing two sequential samples from the patient with inv(16) and NRAS mutation, it was shown that the mutation had occurred after the inversion. Since no NRAS mutations were detected among the t(8;21) samples and only 1 was found in the inv(16) group, we conclude that acute myeloid leukaemias with t(8;21) or inv(16) generally arise and progress without the involvement of NRAS mutations.

Acute Disease↗
PubMedDate not supplied

Liquid chromatographic determination of residual nitrite/nitrate in foods: NMKL collaborative study.

Nitrite and nitrate are used as additives in the food industry to provide color and taste and to control undesirable gas and flavor production by anaerobic bacteria by virtue of their antimicrobial properties. The analytical method that has been widely used to determine nitrite and nitrate involves the use of toxic cadmium. In response to a request from the Nordic Committee on Food Analysis, a study was performed to obtain an alternative chromatographic method to determine residual nitrite and nitrate in meat products. The study was done in 3 stages: (1) comparative evaluation of the performance of 3 liquid chromatographic methods, (2) internal validation of the selected ion chromatographic method, and (3) a collaborative study in which 17 laboratories from European countries participated. Furthermore, the applicability of the method to matrixes other than meat and meat products was demonstrated. The results of the collaborative study show that the European Prestandard prENV 12014-4 is well suited for the determination of nitrite and nitrate in different foods (e.g., meat products, vegetables, baby food, and cheese). The limits of detection for nitrite and nitrate ions are 1 and 10 mg/kg, respectively. Recoveries of residual nitrite/nitrate ranged from 96 to 108%. Repeatability and reproducibility were satisfactory.

Anions↗
PubMedDate not supplied

Epstein Barr virus (EBV) carrying cells in blood of Hodgkin's disease (HD) and non-Hodgkin lymphoma (NHL) patients with high antibody titers against EBV capsid antigens (VCA).

Three patients with Hodgkin's disease (HD) and 7 patients with non Hodgkin lymphoma (NHL) who had high antibody titers against Epstein Barr virus (EBV) capsid antigens (VCA) were studied for the occurrence of EBV carrying B cells in the blood. The outgrowth of lymphoblastoid cell lines (LCLs) in their blood lymphocyte culture was tested in the presence of Cyclosporin A, which abrogates the growth inhibitory effect of T cells. Transformation occurred in the cultures of 4/10 patients and 4/10 age matched healthy individuals. The frequency of transformation in wells seeded with identical cells number from these 4 individuals in each group did not differ. Thus the lymphoma patients with high anti VCA titers did not show elevated level of EBV carrying B cells in the blood.

Aged↗
PubMedDate not supplied

Enzymatic/chemical analysis of dietary fiber.

The Uppsala methodology for rapid analysis and characterization of total dietary fiber, defined as the sum of dietary fiber polysaccharides (DFP) and Klason lignin, was studied. A sugar- and starch-free residue was prepared by treatment with a thermostable amylase and amyloglucosidase. Neutral DFP residues were quantified by gas chromatography as alditol acetates after acid hydrolysis of this residue, and the acid-insoluble fraction, Klason lignin, was determined gravimetrically. Uronic acid residues were quantified by decarboxylation of the original sample. The efficacy of the Uppsala methodology was tested with foods varying in fiber content and composition, including heat-treated samples. The present method allowed the analysis of up to 40 samples per week. It had good repeatability and coefficients of variation of 3-5% for the main fiber components. Fiber contents determined with the method were higher than those determined with a similar method that excludes Klason lignin and starch resistant to amylases but soluble in dimethyl sulfoxide and lower than those determined with an enzymatic/gravimetric method. Important aspects of fiber analysis, like enzyme purity and the recovery of soluble fiber on ethanol precipitation, also were investigated.

Acetylation↗