Distortion and unwinding of the helical structure in polymer-stabilized short-pitch ferroelectric liquid crystal.

We report the effect of an anisotropic polymer network formed from an achiral photoreactive monomer in a short-pitch chiral SmC* phase on the distortion and the unwinding of the helical structure of the ferroelectric phase. The electro-optical behaviour and ferroelectric properties were experimentally determined for films containing various polymer concentrations. The critical field, E(u), for the transition from the distorted structure to the homogeneous state was measured as a function of polymer concentration. A linear increase of E(u) versus polymer concentration was observed, showing that the helical structure of the short-pitch SmC* phase was stabilized by the polymer network. This behaviour was expected to be a consequence of the increase of the apparent elastic constants of the ferroelectric liquid crystal stabilized by the anisotropic polymer network films. The polymer network morphology was investigated using atomic-force microscopy, revealing a twisted structure of the polymer fibers. This twisted structure was transferred onto a polymer network during the polymerization process within a short-pitch SmC* phase. The increase of the apparent elasticity can then be interpreted by a strong interaction between polymer network and the liquid-crystal molecules. From our experimental data, the coupling coefficient, W(p), characterizing this interaction was evaluated for all studied polymer concentrations.

[Acute myeloblastic leukemia without maturation (AML-M1) with basophilic elements and associated with translocation t(6;9)]. / Leucémie aiguë myéloblastique sans maturation (LAM1) avec éléments basophiles associée à la translocation t(6;9).

The clinical, hematological, and cytogenetic data from a 4 year-old child with acute myeloid (AML-M1) and basophilia is reported. Interestingly, cytogenetic investigations revealed the presence of the translocation t(6;9) (p23;q34). This abnormality is rare and associated with myelodysplastic syndromes or with subtypes of acute myeloid leukemia (M1, M2, M4, M7), usually with preceding or underlying myelodysplasia. The prognosis is poor, without response to chemotherapy regimen alone. Allogeneic bone marrow transplantation appears likely to be a more appropriate treatment.

Static and dynamic electro-optic properties of a SmC* phase in surface stabilized geometry and dispersed in the polymer matrix.

Comparative electro-optical measurements have been made on a ferroelectric liquid crystal (FLC) in surface stabilized geometry and confined to an ellipsoidal cavity within a polymer matrix. The static and dynamic electro-optical characteristics were measured for both systems and show qualitatively similar behaviours. A fast switching and important bistability were observed and characterized as a function of the applied electric field strength. The switching time between the two stable states of the surface stabilized cell was found to be longer than that found for the composite films. We argue that the faster switching dynamic of the FLC in cavities is due to the enhance of the rotational mobility of the molecules, probably (and partly) because of the "soft" anchoring character of the molecules at the cavity walls. Using a collective switching model in the high field regime, which assume a linear coupling between the spontaneous polarization and the local cavity electric field, we give an estimate of the rotational viscosity of the FLC molecules in the droplets.

Conducting polymers as driving electrodes for Polymer-Dispersed Liquid-Crystals display devices: on the electro-optical efficiency.

Intrinsically conducting polymer (ICP) thin films are used as driving electrodes for Polymer-Dispersed Liquid-Crystals (PDLC) display devices. In order to investigate the electro-optical efficiency of these organic electrodes, three different kinds of conducting polymers, i.e. polyaniline doped with 10-camphorsulfonic acid (PANI(HCSA)), polypyrrole doped with dodecylbenzenesulfonic acid (PPY(DBSA)), and polyethylenedioxythiophene doped with polystyrenesulfonate (PEDOT(PSS)), were prepared or purchased, and coated either on glass or plastic substrates. Optical absorption studies in the UV-Vis range of the conducting polymer-coated substrates were first performed showing the presence of conducting species for the three types of polymers. The electrical characteristics of the resulting films were measured with the four-probes technique. PANI(HCSA) exhibits a higher conductivity sigma approximately 122 S x cm(-1) (RS=1.2x10(3) Omega x (-1)) compared to PPY(DBSA) sigma approximately 2.6 S x cm(-1) (RS=150.7x10(3) Omega x (-1)), and PEDOT(PSS) sigma approximately 1.6 S x cm(-1) (RS=637.3x10(3) Omega x (-1)). It is also shown that for a given conducting polymer, its electrical conductivity decreases when a plastic substrate is used. These observations have been related to significant morphological changes observed by scanning electron microscopy (SEM). A mixture of Norland Optical Adhesive 65 and nematic liquid-crystal E7 in the weight ratio (35:65) was used as precursor of the PDLC material. Better electro-optical responses (transmission properties, drive voltages and switching times) of PDLC films were obtained for devices prepared with (PPY(DBSA))-based electrodes. The electro-optical performances of the PDLC display devices also depend on the nature of the ICP substrate used.

Leukaemic small cell variant anaplastic large cell lymphoma during pregnancy.

The history of a 28-year-old woman with anaplastic large cell lymphoma (ALCL) in the first trimester of her pregnancy is reported. Investigations allowed to diagnose a T-cell CD30 positive ALCL, which appearance is rare during pregnancy. Moreover, the atypical lymphoid cells were found in the peripheral blood and were predominantly small to medium sized with nuclear irregularities and cytoplasmic azurophilic granules, which allowed the hypothesis of leukaemic presentation of a small cell variant ALCL. A variant of the t(2:5)(p23:q35) was found [del(2)(p22)]. The patient died shortly after diagnosis.

[Pseudoleucopenia due to in vitro leukocyte agglutination polynuclear neutrophils: experience of a laboratory, review of the literature and future management]. / Pseudoleucopénie par leuco-agglutination in vitro des polynucléaires neutrophiles: expérience d'un laboratoire, revue de la littérature et conduite proposée.

Leukoagglutination is a rare EDTA-dependent phenomenon resulting in a spurious minoration of the leukocyte count performed using automated analyzers. We described seven cases. The leukocyte agglutination was detected by unstable WBC count, abnormal WBC histograms and presence of clusters of polymorphonuclears on the smear. PMN aggregates of 3 to 10 cells or bigger were observed. Discrepancies between the erroneous automated WBC count and the real count were moderate in most cases. Leukoagglutination was related to lymphoproliferative disorders, infections, alcoholic liver diseases, auto-immune diseases. Inflammatory context seemed to be requested. For few patients, the artefact occurred regardless of the type of anticoagulants (lithium heparin, buffered sodium citrate) and warming at 37 C did not always increase the WBC. Dilution in Unopette chambers was required. We confirmed that leukoagglutination of PMN was an in vitro artefact EDTA and/or temperature mediated.

Experimental observation of multicritical behaviors in pressure-temperature diagrams of pure compounds with twist grain boundary phases.

In order to study critical behaviors of pure compounds anticipated by Renn and Lubensky's theoretical calculations, high-pressure experiments have been performed on six tolan series homologous to the 3-fluoro-4-[(R) or (S)-methylheptyloxy]-4'-(4"-alkoxy-2",3"-difluorobenzoyloxy), which exhibit the twist grain boundary (TGB(A) and TGB(C)) mesophases. Measurements were carried out by thermobarometric analysis. Six pressure-temperature phase diagrams are determined. The studies establish the existence of multicritical points twisted-smectic-C (S*(C))-TGB(C)-TGB(A), TGB(C)-TGB(A)-cholesteric nematic (N*) and S*(C)-TGB(C)-N* for single component systems in pressure-temperature (P-T) phase diagrams. Our results also show that a pressure increase has the same effect on the (P-T) phase diagrams as a decreasing number of carbon atoms in the aliphatic chain; then pressure change can have the same effects on intermolecular interactions as those observed when shortening the molecular length. The existence of transition lines with negative slope values was also found. The experimental results are in qualitative agreement with the model proposed by Renn and Lubensky.

Indolent course as a relatively frequent presentation in T-prolymphocytic leukaemia. Groupe Français d'Hématologie Cellulaire.

T-prolymphocytic leukaemia (T-PLL) is a rare disorder with a poor outcome. Presentation features were studied in 78 T-PLL cases. Although 53 patients (group A) presented with typical progressive disease including rapidly increasing leucocytosis. 25 patients (group B) experienced an initial indolent clinical course with stable moderate leucocytosis. The morphology and antigenic profile of abnormal cells were similar in both groups, except for a lower incidence of CD45RO+ CD45RA- pattern in group B. A high incidence of inv(14)(q11;q32), t(14;14)(q11;q32) and i(8)(q10) chromosomal abnormalities were found in both groups. After an initial indolent phase (median 33 months; 6-103 months), 16 group B patients progressed to an aggressive stage with clinical and laboratory features similar to group A. Moreover, median survival after progression was short in both groups. In conclusion, T-PLL may start as an indolent disease similar to that reported in ataxia telangectasia. In this rare genetic disorder, some patients develop stable T-cell clones which progress toward T-PLL-like leukaemia. Moreover, ATM gene mutations have been reported in T-PLL. Thus, both diseases are likely to be closely related.

Myelodysplastic syndromes in childhood: is the FAB classification relevant? Report of 81 children from a French multicentre study. French Group of Cellular Hematology.

We reviewed the peripheral blood and bone marrow smears of 81 children with myelodysplastic syndrome (MDS). The morphological FAB classification was applicable in 59 children (72.8%): RAEB and RAEBt were the most frequent, 32 cases (39.5%). CMML was observed in 15 cases (18.5%) and in 25% of them, serological evidence for a recent EBV infection was demonstrated. In 22 cases (27.2%), the FAB classification was not convenient. In some of these children, dysmyelopoiesis was associated with constitutional disorders. Among these various inherited conditions, Down syndrome in which myelodysplasia is the expression of an abnormal clonal hematopoiesis, and mitochondrial cytopathies in which MDS is the hematological expression of a polyclonal multi-organ disease. The FAB classification does not appear to be satisfactory for all the disorders included in the group of childhood MDS and should be modified for specific use in children.

[Myelodysplastic syndromes in children, Groupe d'étude des myélodysplasies de l'enfant de la Société d'hématologie et d'immunologie pédiatrique (SHIP)]. / Syndromes myélodysplasiques de l'enfant. Groupe d'étude des myélodysplasies de l'enfant de la Société d'hématologie et d'immunologie pédiatrique (SHIP).

Myelodysplastic syndromes (MDS) in children constitute a heterogeneous disorder, including 'primary' MDS and MDS associated with constitutional abnormalities. The Franco-American-British (FAB) cytological classification for adults can be applied for childhood in 50 to 100% of the cases. The transformation into acute myeloblastic leukemia often occurs, but stabilisation or spontaneous regression of the disease may also be observed. The therapeutic decision is difficult because there is no predictive factor of the course of the disease. Allogenic bone marrow transplantation is the best curative option when treatment is necessary.

Myelodysplastic syndromes in childhood: report of 49 patients from a French multicentre study. French Society of Paediatric Haematology and Immunology.

We describe the clinical, cytological and cytogenetic features of 49 cases of myelodysplastic syndromes (MDS) in childhood. Three children had received prior cytotoxic treatment (group 1); all of these had cytogenetic abnormalities and died shortly after diagnosis. 22 children had constitutional anomalies (group 2). The remaining 24 MDS were considered as 'primary' (group 3). Hypoplastic marrow was found in nine cases, and only 53% of the MDS fitted the adult FAB classification. Transformation to AML occurred in 11 cases, development of aplastic anaemia in three cases, and spontaneous remission in one case each of RA and RAEB. Differences were observed between groups 2 and 3 in terms of mean age at diagnosis (11.1 months v 5 years), rate of cytogenetic anomalies (15% v 38%) and rate of progression towards acute leukaemia (13% v 29%). In group 2, all the fur girls studied exhibited a polyclonal pattern of X-inactivation, which suggests that MDS may be only the haematological expression of an embryological defect with different target tissues. This study suggests that some MDS in childhood can exhibit particular features such as congenital anomalies associated with MDS, bone marrow hypoplasia, polyclonality, and spontaneous remission. It emphasizes that the FAB classification is not adequate for children and addresses the question of whether these MDS are always malignant diseases.

Macrophage activation syndromes.

The clinical and laboratory features of 47 cases of macrophage activation syndrome (MAS) were reviewed in a workshop within the Groupe Français d'Hématologie cellulaire. There was no predilection for a particular age group, while common symptoms at presentation included fever, hepatic and splenic enlargement and profound depression of blood count. Examination of bone marrow aspirates allowed diagnosis to be established in almost all cases. The most characteristic sign of MAS was the presence of well differentiated macrophages without notable cytologic abnormalities but shown to be actively ingesting haematopoietic elements. Haemophagocytic syndromes generally occur in patients who develop infections in the context of preexisting immunologic abnormalities or neoplasms. In the majority of patients evolution of the disease was regressive, once spontaneously but often after antibiotic, antiparasitic and/or antiviral treatment accompanied or not by corticotherapy and/or chemotherapy. Some regressive phases were followed by more or less long term relapse, especially in the case of associated systemic lupus erythematosus. There exists at present no explanation for the occurrence of MAS, although one may remark its association with other pathologies, in particular congenital or acquired immune deficiencies and haemopathies. Several hypotheses have been proposed to explain the appearance and evolution of the disease and at present two pathways of investigation of MAS seen to merit attention: exploration of macrophages themselves and their secretion products and exploration of lymphocytes and NK cells. The current possibilities for these investigations should lead to a greater understanding of the physiopathology of MAS and it is to be hoped that a better application of appropriate therapy will enable control of its evolution.

[Legionnaires' disease in hairy cell leukemia. 2 new cases]. / Maladie des légionnaires au cours d'une leucémie à tricholeucocytes. Deux nouvelles observations.

We report the cases of two patients who developed legionnaires' disease during the course of hairy cell leukaemia. The clinical features are described with special emphasis on the severity of illness in one patient and marked jaundice in both. These cases demonstrate the enhanced susceptibility to Legionella pneumophila infections in patients with hairy cell leukaemia. We therefore suggest a reevaluation of empiric antimicrobial treatment of pneumonia in such patients.