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Biomedical subjects

B Dreyfus

Publications and source records attributed to B Dreyfus.

At least 19 recordsLinked to original sources
PubMed1994

High incidence of serum monoclonal Igs detected by a sensitive immunoblotting technique in B-cell chronic lymphocytic leukemia.

In a prospective study in 65 untreated patients with early-stage B-cell chronic lymphocytic leukemia (B-CLL), serum monoclonal Igs (moIg) were evidenced in 80% of cases by a sensitive immunoblotting procedure. These low-abundance moIg were generally undetectable by immunoelectrophoresis and individual sera often contained several of them. Their kappa/lambda ratio was close to 1 instead of 2.8 for the lymphocyte surface Igs. A monoclonal IgM of the same light-chain type as the lymphocyte surface IgM was found in 26 sera only. The distribution of the heavy-chain classes and subclasses and light-chain types of the serum moIg was similar to those observed in aging (with a higher incidence and no correlation with age in B-CLL) and conditions with defective T-cell functions. Using a specific filter affinity-transfer assay, rheumatoid factors were detected in 58.5% of sera. However, homogeneous anti-IgG antibodies corresponding to a monoclonal IgM of the same light-chain type as the surface IgM were found in 10 patients only. These data suggest that the majority of discrete serum moIg in B-CLL are not secretion products of the leukemic clones and likely result from the immunodeficiency state inherent in the disease.

Adult↗
PubMed1994

Phenotypic and genotypic characterization of bradyrhizobia nodulating the leguminous tree Acacia albida.

Rhizobial isolates that were obtained from both surface and deep soil samples in the Sahelian and Sudano-Guinean areas of Senegal (West Africa) under Acacia albida trees were compared with representative strains of known rhizobial species and genera. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of proteins was used to determine the taxonomic positions of these organisms and the relationships between isolates obtained from the surface and isolates obtained from deep soil. Most of the isolates belonged to eight electrophoretic clusters containing representative strains of Bradyrhizobium japonicum, Bradyrhizobium elkanii, and Bradyrhizobium sp. Isolates were also characterized by the Biolog system, and the results were compared with the results obtained by SDS-PAGE of total proteins; the level of correlation was very low. DNA-rRNA hybridizations with 16S or 23S rRNA from Bradyrhizobium japonicum LMG 6138T (T = type strain) confirmed that most of the protein electrophoretic clusters belong in the Bradyrhizobium-Rhodopseudomonas rRNA complex. Sequencing of 16S rRNA genes showed that some of the A. albida-nodulating isolates belong to a separate lineage together with representatives of other protein electrophoretic clusters. Other isolates that belong to the same electrophoretic cluster as the type strain of Bradyrhizobium japonicum are considered members of the lineage represented by this type strain. The first lineage is as far removed from Bradyrhizobium japonicum as it is from the genus Afipia, Blastobacter denitrificans, and the genus Rhodopseudomonas. The possible relationship among electrophoretic group, geographic origin, and depth of isolation at a particular site is discussed.

Acacia↗
PubMed1994

Root nodulation of Sesbania rostrata.

The tropical legume Sesbania rostrata can be nodulated by Azorhizobium caulinodans on both its stem and its root system. Here we investigate in detail the process of root nodulation and show that nodules develop exclusively at the base of secondary roots. Intercellular infection leads to the formation of infection pockets, which then give rise to infection threads. Concomitantly with infection, cortical cells of the secondary roots dedifferentiate, forming a meristem which has an "open-basket" configuration and which surrounds the initial infection site. Bacteria are released from the tips of infection threads into plant cells via "infection droplets," each containing several bacteria. Initially, nodule differentiation is comparable to that of indeterminate nodules, with the youngest meristematic cells being located at the periphery and the nitrogen-fixing cells being located at the nodule center. Because of the peculiar form of the meristem, Sesbania root nodules develop uniformly around a central axis. Nitrogen fixation is detected as early as 3 days following inoculation, while the nodule meristem is still active. Two weeks after inoculation, meristematic activity ceases, and nodules then show the typical histology of determinate nodules. Thus, root nodule organogenesis in S. rostrata appears to be intermediate between indeterminate and determinate types.

Cell Differentiation↗
PubMed1994

Proliferative response of B chronic lymphocytic leukemia lymphocytes stimulated with IL2 and soluble CD23.

The in vitro proliferative response of purified B-chronic lymphocytic leukemia (B-CLL) lymphocytes cultured in the presence of soluble CD23 (sCD23) with or without IL2 was compared to the responses induced by phorbol 12-myristate 13-acetate (PMA), Staphylococcus aureus strain Cowan I (SAC), IL1, IL2, IL4, IL6 and the combination of IL2 and interferon (IFN) alpha or IFN gamma. As expected, B-CLL lymphocytes proliferated with PMA, SAC and IL2 with a clear enhancement of the IL2-induced response by IFN alpha or IFN gamma. They failed to proliferate in response to sCD23, IL1, IL4 or IL6 alone nor to the combinations of sCD23 and any of the 3 latter cytokines. However, sCD23 significantly increased the proliferation of B-CLL cells induced by IL2, suggesting a protective effect of sCD23 on apoptosis. Serum levels of sCD23 and CD23 membrane expression were high in every patient which is compatible with the hypothesis of an autocrine or paracrine activation loop. Detectable CD23 expression was lost in all cultures except for that stimulated by PMA. Only supernatants of PMA-stimulated cultures contained high sCD23 levels.

Adult↗
PubMed1993

Role of the fixGHI region of Azorhizobium caulinodans in free-living and symbiotic nitrogen fixation.

A 19-kb DNA region containing genes sharing homology with Rhizobium meliloti fixNOQP and fixGHI was isolated from a genomic library of Azorhizobium caulinodans. Identity of fixG was confirmed by partial nucleotide sequencing. Mutant strains in the fixGHI region were constructed by deletion or Tn5 insertions. In contrast with the situation in R. meliloti, the mutants still displayed a significant nitrogenase activity in symbiosis.

Base Sequence↗
PubMed1993

Chromosomal analysis of purified B-chronic lymphocytic leukemia lymphocyte cultures: comparison with whole blood cultures and in situ hybridization.

Chromosomal analysis of stimulated whole blood cells and purified B lymphocytes was performed in 13 stage A(0) and 1 stage C(IV) chronic lymphocytic leukemia (B-CLL) patients. Abnormal clones were found in 6 cases in purified B lymphocytes cultures and in a single one in whole blood cultures. In situ hybridization with a chromosome 12 probe was in accordance with the chromosomal analysis of purified B-CLL lymphocytes and not with the results obtained using whole blood culture. Cytogenetic analysis of isolated B cells is simple and sensitive. It enhances the detection of abnormal clones in B-CLL and applied to larger series of patients, it should allow a precise evaluation of the incidence of chromosomal abnormalities in CLL and of their clinical (prognostic) significance.

Aged↗
PubMed1990

Cytogenetics and molecular analysis in chronic myelogenous leukemia patients treated by interferon and chemotherapy.

A new combination regimen including chemotherapy and interferon was started in 1986 for the treatment of 24 chronic myelogenous leukaemia patients in chronic phase. Complete cytogenetic remission were noted in 10 patients and 6 of them are in sustained remission. The overall survival was 70% at 40 months. However, a minimal residual disease was detected in the 3 patients tested with the polymerase chain reaction. In addition no correlation was detected between the site of the breakpoint and response to therapy.

Adult↗
PubMed1989

Combined therapy interferon and chemotherapy in chronic myelogenous leukemia.

In view of the results achieved by others with interferons and also with low doses of Cytosine-arabinoside, we have treated 24 patients with IFN alpha 2a and Hydroxyurea for induction, with addition of low dose Ara-C during IFN maintenance therapy when the cytogenetic results were deemed insufficient. Complete hematological responses were obtained in 75% of the cases. Cytogenetic responses were noted in 83% of 12 previously untreated (complete or almost complete response in 3) and in 50% of previously treated patients (complete or almost complete response in 3 patients).

Adolescent↗
PubMed1989

Karyotypes of 33 patients with clonal aberrations in chronic lymphocytic leukaemia. Review of 216 abnormal karyotypes in chronic lymphocytic leukaemia.

We report on 33 unpublished patients with clonal anomalies in chronic lymphocytic leukaemia. The literature was thoroughly reviewed in order 1) to quantify the frequency of anomalies found in chronic lymphocytic leukaemia and to give new status to the rarest, 2) to determine whether a given anomaly was an additional anomaly and/or a primary anomaly, and 3) to find out whether strong associations between different anomalies exist in this disease.

Chromosome Aberrations↗
PubMed1988

[Acute leukemia with translocation (8;16)].

Three cases of M5 acute leukemia, 1 with a t(8;16)(p11;p13), 2 with variant translocations, both with a breakpoint at band 8p11, t(6;8)(q27;p11) and t(8;19)(p11;q13) are reported and 12 other published cases reviewed. This is a rare new entity, of variable but rather poor prognosis, seen from birth to 75 years of age, with several cases in infants. Leukemic cells, which often show conspicuous phagocytic activity on bone marrow smears, bear both monocytic and granulocytic markers in at least some cases. The best therapeutic regimen is not well-defined. The molecular basis of the disorder remains to be elucidated.

Adult↗
PubMed1986

[Disseminated aspergillosis in acute leukemia probably chemically-induced].

One case of invasive aspergillosis in patient with myeloblastic leukemia probably induced by chimiotherapy is reported. Aspergillosis is a severe infection in immunodepressed host with 70 to 80% of mortality. Early diagnosis can be often carried by broncho-alveolar lavage, route of entry is always pulmonary one. Rapidly established antimycotic treatment can avoid death. Laminar air flow rooms and air spores numeration allow prevention of this infection in the immunodepressed host.

Adult↗