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Biomedical subjects

G Lenoir

Publications and source records attributed to G Lenoir.

At least 163 records · Page 9Linked to original sources
PubMed1987

Selective lack of antibody to a component of EB nuclear antigen in patients with chronic active Epstein-Barr virus infection.

The sera of 12 patients with presumed chronic active Epstein-Barr virus (EBV) infection lacked antibody to a component of the Epstein-Barr nuclear antigen (EBNA) complex encoded by the BamHI K fragment of viral DNA. This anomaly, detected in approximately 18% of sera obtained from patients with a diagnosis of "chronic mononucleosis," was more often found in patients with severe disease (approximately 32%) who had objective clinical findings and markedly elevated antibody titers to EBV replicative antigens than in those patients with the "fatigue syndrome" (10%). The lack of antibody to the K nuclear antigen is specific because most of those who did not have antibody to the K antigen made antibody to other latent nuclear (EBNA 2) antigens or nuclear early antigens. Such patients are thus able to lyse immortalized cells, release nuclear products, and present them to the immune system. Three hypotheses are suggested to explain the lack of antibody to the K antigen: a viral mutation, a failure of immune recognition, or lack of in vivo expression of the antigen due to extensive viral replication. Lack of antibody to one component of EBNA may serve as an objective serological marker for certain patients with chronic EBV infection.

Adolescent↗
PubMed1987

B-cell maturation stages of Burkitt's lymphoma cell lines according to Epstein-Barr virus status and type of chromosome translocation.

This study addressed the possible relationship between B-cell maturation stage of Burkitt's lymphoma (BL) cell lines and Epstein-Barr virus (EBV) status, ethnic group, or type of chromosome translocation. Fifty-seven cell lines obtained at the International Agency for Research on Cancer from 51 patients were studied. Cytogenetic analyses of 54 cells lines were available. Cell size, surface immunoglobulins (sIgs), cytoplasmic immunoglobulins (cIgs), mouse red blood cell receptors, and reactivity with various monoclonal antibodies were assessed. Immunoglobulin (Ig) class secretions were measured in the supernatant of 2- and 5-day cultures from 33 cell lines, with the use of a sensitive enzyme-linked immunosorbent assay technique. From this study, BL appears to cover a broad range of the B-cell differentiation sequence, since the following Ig phenotypes were observed: null cells (sIg-, cIg-), large pre-B-cells (intracytoplasmic mu-chains), small B-cells (sIg+, cIg-), and various types of secreting B-cells (sIg+, cIg+). Among the latter, various patterns of cIg could be defined (perinuclear, paranuclear, and vesicular). B-cell maturation stages were correlated with the amount of secreted Ig. In sIg+ cell lines, different classes of Ig were found: 35 IgM, 10 IgM plus IgD, 4 IgG, and 1 IgA. None of the different monoclonal antibodies used was specific to a precise stage of maturation. The stages of maturation were correlated with neither the type of chromosome translocations of BL nor the presence of EBV genome, but the most immature cell lines were all EBV positive and most of them originated from African patients. In contrast with acute lymphoblastic leukemia, the common acute lymphocytic leukemia antigen (CD10) was expressed on nearly all BL cell lines of intermediate maturation stages but only on half of the pre-B ones. In addition, none of the cell lines tested was found to react with CD5 antibodies, which recognize most of the chronic lymphocytic leukemia of the same stage of maturation as that in the B-lymphocyte lineage.

Adolescent↗
PubMed1987

[The effect of benzydamine on the generation and interaction of reactive oxygen species and cyclo- and lipoxygenase].

Pharmacological mechanisms of benzydamine (Tantum) are studied which are of relevance for the antiinflammatory properties of this non-steroidal antiinflammatory drug (NSAID). Benzydamine most effectively inhibits the generation of reactive oxygen species by murine neutrophils (IC50 1.7 X 10(-5) mol/l). Piroxicam, indomethacin and acetylsalicylic acid are ineffective. Benzydamine, however, does not interfere with xanthine oxidase-dependent superoxide anion radical formation or epinephrine oxidation. The other tested NSAID are as well inactive. The findings confirm the missing cyclooxygenase inhibition of benzydamine (IC50 greater than 10(-3) mol/l), contrary to the other NSAID which are strong (indomethacin IC50 6 X 10(-8) mol/l; piroxicam IC50 2 X 10(-7) mol/l) or moderate cyclooxygenase inhibitors (acetylsalicylic acid IC50 10(-5) mol/l). LTB4 generation via the lipoxygenase is only inhibited by indomethacin (EC50 3.6 X 10(-5) mol/l). Benzydamine appears unique among other NSAID by its relatively strong interference with the generation of reactive oxygen radicals and the lack of cyclooxygenase inhibition.

Animals↗
PubMed1986

EBV-negative and -positive Burkitt cell lines variably express receptors for B-cell activation and differentiation.

The expression of receptors for proliferation and differentiation factors was analyzed by indirect immunofluorescence on 29 Burkitt lymphoma (BL) cell lines previously classified into 3 groups on the basis of their reactivity with 8 monoclonal antibodies (MAbs), including anti-CALLA, BL13 and TU1. BL13 and HB5 antibodies recognize different epitopes of the EBV/CR2 receptors. The determinant recognized by BL13 has been previously shown to be expressed only on cell lines of the first two groups, supposed to derive from the germinal center and to be negative on a third group of lines of putative BM origin and established from sporadic cases of BL. In contrast, and as expected from its reactivity on normal B cells in the BM or in the lymph nodes, HB5 antibody reacts with all BL lines except one. The receptor for transferrin is expressed on the 29 lines. Two new MAbs, Bac-1 and B1H5, could recognize respectively receptors for BCGF1 and BCGF2. Bac-1 reacts with 15 of 17 BL lines belonging to the first two groups and 7 of 12 BL lines of the third group; 14 of 15 EBV + lines express Bac-1. No BL line expresses B1H5. The IL2 receptor is weakly expressed on 5 EBV + cell lines and one EBV (-) line. All delta are BCGF1-positive. The almost constant expression of BCGF1 receptor on EBV + cell lines is the only strict relation between the expression of receptors for growth factors and their characteristics (i.e. EBV association, translocation, ethnic origin and clinical presentation). The maturation stage or the origin of BL cell lines in relation to the expression of growth factor receptors and the functional significance of these receptors will be discussed.

Antigens, Neoplasm↗
PubMed1986

Differential recognition of tumor-derived and in vitro Epstein-Barr virus-transformed B-cell lines by fetal calf serum-specific T4-positive cytotoxic T-lymphocyte clones.

Two interleukin-2 (IL-2)-dependent cytotoxic T-cell clones were obtained by limiting dilution from a lymphocyte culture stimulated in vitro with the autologous Epstein-Barr virus-transformed lymphoblastoid cell line (LCL) in the presence of fetal calf serum (FCS). Both clones uniformly had a T3+, T4+, Dr+ phenotype and lysed autologous B blasts, the autologous LCL, and allogeneic B cell lines sharing major histocompatibility complex (MHC) class II antigens. The cytotoxic function was triggered by FCS-derived components. There was no killing if the sensitive targets were cultured in serum-free medium or in medium supplemented with human serum. Sensitivity to lysis could be restored by exposing the targets to FCS for at least 6 hr at 37 degrees C. Monoclonal antibodies directed to T-cell-specific surface antigens and MHC class II antigens inhibited lysis with different efficiencies depending on the target cell origin. Killing of Burkitt's lymphoma (BL)-derived cell lines was blocked more easily than killing of LCLs. LCLs but not BL lines induced proliferation of the T-cell clones in the absence of exogenous IL-2. The differences were not related to quantitative variations in the expression of MHC class II antigens, indicating that BL lines differ from LCLs in other cell membrane properties that may influence antigen presentation. The results suggest that the affinity of effector/target binding, which is probably influenced by the concentration of antigenic determinants expressed on the target cell membrane, determines whether proliferative responses or cytotoxicity are induced in the antigen-recognizing T cells.

Antibodies, Monoclonal↗
PubMed1986

Alternative involvement of two cytogenetically distinguishable breakpoints on chromosome 8 in Burkitt's lymphoma associated translocations.

The chromosomes of 16 Burkitt's lymphoma (BL) derived cell lines were submitted to high-resolution G-band analysis. They included seven lines with t(8;14), three with t(2;8), and four with t(8;22). The translocation breakpoint in chromosome #14 was located in 14q32.3, in chromosome #2 in 2p11.1, and in chromosome #22 in 22q12.12. In chromosome #8, the translocation breakpoint was located in two cytogenetically distinct subbands: 8q24.1 in cell lines with t(8;14) and t(2;8) and 8q24.22 in cell lines with t(8;22). In the light of recent molecular findings, these results indicate that the distance between the c-myc gene, located in 8q24, and the Ig sequences might be much larger in BL lines with t(8;22) than in those with t(2;8).

Burkitt Lymphoma↗
PubMed1986

A translocated human c-myc oncogene is altered in a conserved coding sequence.

We have cloned and characterized a c-myc (now designated MYC) oncogene that had been translocated into the mu switch region of the immunoglobulin heavy chain locus in a Burkitt lymphoma cell line. The breakpoint of the translocation occurs within the first intron of the c-myc gene, thereby separating the untranslocated first exon from the two coding exons. Transcription from the translocated gene arises from a cryptic promoter within the first intron, which produces a 438-nucleotide untranslated 5' region. The amino acid sequence of the protein encoded by the c-myc gene has been substantially altered. In particular, a compensating set of frameshift mutations alters a string of 24 amino acids in a region of the protein tightly conserved in human, mouse, and chicken c-myc genes as well as in the human N-myc and L-myc oncogenes. Despite this, the mutated gene retains a reduced transforming ability in a rat embryo fibroblast focus-formation assay.

Amino Acid Sequence↗
PubMed1986

[Transient erythroblastopenia in young children].

A case of transient erythroblastopenia of childhood is reported. This syndrome occurred in a 13 month-old girl. Initial signs were a 6.1 g/dl hemoglobin level and severe erythroblastopenia. Spontaneous recovery occurred after a few weeks. No etiology could be found.

Anemia, Aplastic↗
PubMed1986

[Requests for prenatal diagnosis from parents of children with cystic fibrosis].

The request for prenatal diagnosis of cystic fibrosis has been evaluated by an interview during a visit at a cystic fibrosis clinic among 32 couples whose one or several children are affected. Six couples resorted to the procedure between June 1984 and October 1985. In all the cases, in these families the only child (or children) alive was affected. The diagnosis of the disease in the first affected child reduces the number of children planned by the family. The significant use of the test, since its availability points to the existence of a real demand from the parents.

Cystic Fibrosis↗
PubMed1986

[Congenital hyperparathyroidism. 3 cases].

Hypotonia, neonatal respiratory distress with a chest wall deformity should arouse clinical suspicion to the diagnosis of primary hyperthyroidism. The most common signs at this age are hypercalcaemia, increased alkaline phosphatase, low TRPP and radiological changes especially in the hip. Radio-immunological assay of PTH and plasma concentrations of Vitamin D metabolites are important diagnostic aids but the interpretation of these results should take the clinical and familial context into consideration. Rapid bone structural changes, the resistance of the hypercalcaemia to usual therapeutic measures and the progression to rickets justify urgent surgical treatment. Nearly all cases are due to clear cell hyperplasia.

Alkaline Phosphatase↗
PubMed1985

Elevated plasma 1,25-dihydroxyvitamin D concentrations in infants with hypercalcemia and an elfin facies.

We measured plasma concentrations of 1,25-dihydroxyvitamin D (1,25-(OH)2D) in the course of a 6-to-37-month survey of four children with hypercalcemia and an elfin facies (Williams syndrome). Levels of 1,25-(OH)2D were elevated (160 to 470 pg per milliliter) during the hypercalcemic phase of the disease, when the children were five to nine months old, and they decreased thereafter. Plasma 1,25 (OH)2D levels were higher than those found in three children (16 to 60 months old) with the elfin facies syndrome and no hypercalcemia (42 to 71 pg per milliliter) and eight children (1 to 36 months old) with hypercalcemia and no dysmorphy (12 to 140 pg per milliliter), including two children with vitamin D intoxication. Hypercalcemia in the three children with elfin facies was controlled by a low-calcium diet. Serum calcium levels fell to the normal range, and plasma 1,25-(OH)2D levels were normal for age (18 to 105 pg per milliliter) at 14 to 47 months of age, even after appropriate therapy had been discontinued. These observations suggest that hypercalcemia may be the consequence of abnormal synthesis or degradation of 1,25-(OH)2D in children with the elfin facies syndrome.

Calcitriol↗
PubMed1985

Antibody responses to two Epstein-Barr virus nuclear antigens defined by gene transfer.

By transfecting small fragments of Epstein-Barr virus (EBV) DNA into cells, we defined two nuclear antigens, termed M and K, and examined serum from 258 subjects for antibodies against these antigens. We hoped to learn whether such single-antigen systems would clarify the association of EBV with various diseases. Although reactivity to M antigen was found in only 14 per cent of healthy EBV-seropositive subjects, 90 per cent of Chinese and North African patients with nasopharyngeal carcinoma had antibody to M. Nearly all persons (96 per cent) who were EBV seropositive, as judged by their serologic reaction to a nuclear antigen encoded by the complete virus (EBNA), had a reaction to K antigen. However, serum samples from three patients with chronic active EBV infection did not react to K, even though the serum contained anti-M titers above 1:1000. Lymphoid cells from one such patient carried a normal gene for K and made K protein of correct size. Therefore, in this patient the absence of antibody to K had not resulted from a viral mutation that destroyed the K protein. These serologic studies show that some patients with chronic active EBV infection have an abnormal immune response to a specific viral gene product.

Adult↗
PubMed1985

Distribution of androgen and estrogen receptors among lymphoid and haemopoietic cell lines.

Estrogen receptors (ER) and androgen receptors (AR) were determined in a series of 23 leukemia or lymphoma cell lines including 8 T-cell lines, 12 B-cell lines, and 3 non lymphoid cell lines. The phenotypic characterization of these cells by currently available immunological markers provides an estimate of their stage of differentiation. The result indicate that none of the investigated cell lines bear simultaneously ER and AR. Four were found to bear ER: U266, RPMI 8226, HL60, IARC/310/LT2, and four to express AR: RAJI, IARC/301/LTI, U937, REH6. The presence of cytosolic receptors was always associated with that of nuclear receptors. The expression of either ER or AR is restricted to discrete maturation stages of different haemopoietic cell lineages. Thus AR were found among the most immature lines of the T, B or monocytic lineage but they could be detected neither in the promyelocytic line HL60, nor in the pluripotential K562. The present results are in keeping with the demonstration of AR in some leukaemic blasts or in non Hodgkin's lymphomas. In contrast with AR, ER are present in two myeloma cell lines, in the promyelocytic cell line, HL60 and in a T-cell line bearing the phenotype of mature suppressor/cytotoxic T cells.

Cell Line↗
PubMed1985

Immunoblastic lymphoma following Hodgkin's disease: a case report with translocation t(8;14) in tumoral cells and sporadic t(7;14) in peripheral lymphocytes.

A non-Hodgkin's lymphoma was observed in a patient who had been treated for Hodgkin's disease (HD). The initial treatment consisted of radiotherapy alone, but following three subsequent relapses, both chemotherapy and radiotherapy were administered several times. Twenty years later, the biopsy of an isolated cervical lymph node revealed a non-Hodgkin's lymphoma. The histologic subtype was immunoblastic. Cytogenetic studies of the tumoral cells revealed a t(8;14)(q24;q32) translocation. At the same time, multiple chromosomal rearrangements were observed in peripheral blood lymphocytes, especially t(7;14)(q35;q12), which was noted in 6 of 53 mitoses. This anomaly, frequently observed in patients with ataxia telangiectasia or severe immunodeficiency, has not previously been described in such circumstances.

Adult↗