Biomedical subjects

Françoise Picard

Publications and source records attributed to Françoise Picard.

5 recordsLinked to original sources

PubMed2006

Deciphering leukemic B-cell chronic lymphoproliferative disorders.

Diagnosis of leukemic B-cell chronic lymphoproliferative disorders (B-CLPD) is a frequent challenge in hematology. In this multicentric study, we prospectively studied 165 new consecutive leukemic patients with B-CLPD selected on the basis of Royal Marsden Hospital scoring system < or =3. The primary aim of the study was to try to decipher the atypical cases and identify homogenous subgroups. Overall, morphological examination contributed to diagnosis in only 20% cases, all of them CD5 negative. Thirty additional cases were CD5 negative suggestive of leukemic marginal zone lymphoma in most cases. The significantly poorer survival of the 26 cyclin D1 positive cases justifies recommending its systematic determination among atypical B-CLPD. CD20 expression segregated clearly two subgroups among CD5 positive cyclin D1 negative B-CLPD. The 17 patients with the CD20 dim profile represent a homogeneous subgroup very close to typical B-cell chronic lymphocytic leukemia (B-CLL) on morphological, phenotypical and cytogenetical criteria. In contrast, the subgroup of 51 patients with a CD20 bright profile is heterogeneous. Their significantly lower p27 expression level suggest the presence of a proliferative component, underlying a more aggressive disease. Further genomic studies are warranted to establish their precise nature. These cases should not be included in the same therapeutic trials as B-CLL.

Aged↗

PubMed2003

Development of a protocol for the isolation of Listeria monocytogenes from sludge.

Given the high level of background flora in sludge, methods for detecting Listeria monocytogenes are not well established. In this study, two critical parameters for the detection of L. monocytogenes were evaluated: the concentration of Listeria sp. in a modified Fraser broth (first stage of the method) and the proportion of L. monocytogenes on Palcam agar (second stage of the method). Concentrations of Listeria sp. estimated in 118 modified Fraser enrichment broths inoculated with four types of sludge, reached 10(4) bacteria per mL for 83% of the positive enrichment broths. Proportion of L. monocytogenes on Palcam agar, which was estimated by transferring all characteristic colonies of Listeria sp. onto Rapid'L Mono agar, was highly variable regardless of the type of sludge. According to these results, we proposed a protocol that consisted of an enrichment in modified Fraser broth for 48 h at 37 degrees C, followed by plating 0.1 mL of appropriate dilutions of broth onto Palcam agar. After an incubation of 48 h at 37 degrees C, a systematic identification of characteristic colonies of Listeria sp. on Rapid'L Mono agar allowed to enhance the detection of Listeria monocytogenes.

Agar↗

PubMed2002

Immunophenotypic clustering of myelodysplastic syndromes.

Myelodysplastic syndromes (MDSs) are heterogeneous diseases of bone marrow (BM) cell precursors for which immunophenotypic characterization is still considered irrelevant despite the accuracy and sensitivity of flow cytometry techniques. The aim of this study was to determine whether immunophenotypic abnormalities could be defined in MDSs and could correlate with the French-American-British classification and cytogenetics. Analysis was performed on 275 BM samples (207 MDS patients, 68 controls) and 25 control blood samples. Immunophenotyping was based on a primary gating of blast cells, monocytes, and granulocytes according to CD45 antigen expression and side scatter light diffraction. Immunophenotypic hierarchical clustering was performed to analyze the results. The data obtained show that (1) immunophenotypic clustering partly discriminates patients with refractory anemia with excess blasts/refractory anemia with excess blasts in transformation (RAEB/RAEB-T), chronic myelomonocytic leukemia (CMML), and refractory anemia/refractory anemia with ring sideroblasts (RA/RARS) for CD45(lo) blast cells and patients with RA/CMML, RARS, and RAEB/RAEB-T for CD45(hi)/side scatter(hi) (SS(hi)) granulocytes; (2) the most discriminating markers were CD16, CD34, CD36, CD38, CD71, and HLA-DR for blast cells and CD11b, CD13, CD33, CD36, CD38, CD71, and HLA-DR for CD45(hi)/SS(hi) granulocytes; (3) clusters related to CD34 expression were associated with high levels of blast cells on BM smear; (4) clusters related to high levels of CD36 expression on CD45(lo) blast cells and CD45(hi)/SS(hi) granulocytes were associated with a poor International Prognosis Scoring System score; and (5) high levels of CD71 expression on CD45(hi)/SS(hi) granulocytes were associated with the RARS category. These results show a close relationship between immunophenotypic abnormalities and BM dysplasia and suggest that flow cytometry could be a future tool for the characterization of MDSs.

Antigens, CD↗

PubMed2002

In vitro proliferation and differentiation of erythroid progenitors from patients with myelodysplastic syndromes: evidence for Fas-dependent apoptosis.

Erythropoiesis results from the proliferation and differentiation of pluripotent stem cells into immature erythroid progenitors (ie, erythroid burst-forming units (BFU-Es), whose growth, survival, and terminal differentiation depends on erythropoietin (Epo). Ineffective erythropoiesis is a common feature of myelodysplastic syndromes (MDS). We used a 2-step liquid-culture procedure to study erythropoiesis in MDS. CD34(+) cells from the marrow of patients with MDS were cultured for 10 days in serum-containing medium with Epo, stem cell factor, insulin-like growth factor 1, and steroid hormones until they reached the proerythroblast stage. The cells were then placed in medium containing Epo and insulin for terminal erythroid differentiation. Numbers of both MDS and normal control cells increased 10(3) fold by day 15. However, in semisolid culture, cells from patients with refractory anemia (RA) with ringed sideroblasts and RA or RA with excess of blasts produced significantly fewer BFU-Es than cells from controls. Fluorescence in situ hybridization analysis of interphase nuclei from patients with chromosomal defects indicated that abnormal clones were expanded in vitro. Epo-signaling pathways (STAT5, Akt, and ERK 1/2) were normally activated in MDS erythroid progenitors. In contrast, apoptosis was significantly increased in MDS cells once they differentiated, whereas it remained low in normal cells. Fas was overexpressed on freshly isolated MDS CD34(+) cells and on MDS erythroid cells throughout the culture. Apoptosis coincided with overproduction of Fas ligand during the differentiation stage and was inhibited by Fas-Fc chimeric protein. Thus, MDS CD34(+)-derived erythroid progenitors proliferated normally in our 2-step liquid culture with Epo but underwent abnormal Fas-dependent apoptosis during differentiation that could be responsible for the impaired erythropoiesis.

Adult↗

PubMed2002

Erythroleukemia: a comparison between the previous FAB approach and the WHO classification.

Erythroleukemia is, within FAB classification, a proliferation of erythroblasts superior to 50% and of myeloblasts superior to 30%. The new WHO classification abolishes the frontier between RAEB-t with 20% and leukemia with 30% of blasts. AML6 variant is a new entity characterized by the proliferation of immature erythroblasts and the absence of non-erythroid blast cells. We analyzed 16 erythroleukemia, 5 RAEB-t and 2 AML6 variants to clarify their relationship. We suggest on survival, karyotype and cytologic characteristics that secondary erythroleukemia are the same entity as RAEB-t, confirming the WHO classification and that amongst de novo erythroleukemia, there is 'AML6 variant' with pure erythroid lineage proliferation.

Adult↗