Multi-time scale analysis of the spatial representativeness of in situ soil moisture data within satellite footprints.

We conduct a novel comprehensive investigation that seeks to prove the connection between spatial and time scales in surface soil moisture (SM) within the satellite footprint (~50 km). Modeled and measured point series at Yanco and Little Washita in situ networks are first decomposed into anomalies at time scales ranging from 0.5 to 128 days, using wavelet transforms. Then, their degree of spatial representativeness is evaluated on a per time-scale basis by comparison to large-spatial scale datasets (the in situ spatial average, SMOS, AMSR2 and ECMWF). Four methods are used for this: temporal stability analysis (TStab), triple collocation (TC), the percentage of correlated areas (CArea) and a new proposed approach that uses wavelet-based correlations (WCor). We found that the mean of the spatial representativeness values tends to increase with the time scale but so does their dispersion. Locations exhibit poor spatial representativeness at scales below 4 days, while either very good or poor representativeness at seasonal scales. Regarding the methods, TStab cannot be applied to the anomaly series due to their multiple zero-crossings and TC is suitable for week and month scales but not for other scales where datasets cross-correlations are found low. In contrast, WCor and CArea give consistent results at all time-scales. WCor is less sensitive to the spatial sampling density, so it is a robust method that can be applied to sparse networks (1 station per footprint). These results are promising to improve the validation and downscaling of satellite SM series and the optimization of SM networks.

Constitutional mismatch repair deficiency syndrome: clinical description in a French cohort.

BACKGROUND: Constitutional mismatch repair deficiency (CMMRD) syndrome is a childhood cancer predisposition syndrome involving biallelic germline mutations of MMR genes, poorly recognised by clinicians so far. METHODS: Retrospective review of all 31 patients with CMMRD diagnosed in French genetics laboratories in order to describe the characteristics, treatment and outcome of the malignancies and biological diagnostic data. RESULTS: 67 tumours were diagnosed in 31 patients, 25 (37%) Lynch syndrome-associated malignancies, 22 (33%) brain tumours, 17 (25%) haematological malignancies and 3 (5%) sarcomas. The median age of onset of the first tumour was 6.9 years (1.2-33.5). Overall, 22 patients died, 9 (41%) due to the primary tumour. Median survival after the diagnosis of the primary tumour was 27 months (0.26-213.2). Failure rate seemed to be higher than expected especially for T-cell non-Hodgkin's lymphoma (progression/relapse in 6/12 patients). A familial history of Lynch syndrome was identified in 6/23 families, and consanguinity in 9/23 families. PMS2 mutations (n=18) were more frequent than other mutations (MSH6 (n=6), MLH1 (n=4) and MSH2 (n=3)). CONCLUSIONS: In conclusion, this unselected series of patients confirms the extreme severity of this syndrome with a high mortality rate mostly related to multiple childhood cancers, and highlights the need for its early detection in order to adapt treatment and surveillance.

Viability of 3h grown bacterial micro-colonies after direct Raman identification.

Clinical diagnostics in routine microbiology still mostly relies on bacterial growth, a time-consuming process that prevents test results to be used directly as key decision-making elements for therapeutic decisions. There is some evidence that Raman micro-spectroscopy provides clinically relevant information from a limited amount of bacterial cells, thus holding the promise of reduced growth times and accelerated result delivery. Indeed, bacterial identification at the species level directly from micro-colonies at an early time of growth (6h) directly on their growth medium has been demonstrated. However, such analysis is suspected to be partly destructive and could prevent the further growth of the colony needed for other tests, e.g. antibiotic susceptibility testing (AST). In the present study, we evaluated the effect of the powerful laser excitation used for Raman identification on micro-colonies probed after very short growth times. We show here, using envelope integrity markers (Syto 9 and Propidium Iodide) directly on ultra-small micro-colonies of a few tens of Escherichia coli and Staphylococcus epidermidis cells (3h growth time), that only the cells that are directly impacted by the laser lose their membrane integrity. Growth kinetics experiments show that the non-probed surrounding cells are sometimes also affected but that the micro-colonies keep their ability to grow, resulting in normal aspect and size of colonies after 15h of growth. Thus, Raman spectroscopy could be used for very early (<3h) identification of grown micro-organisms without impairing further antibiotics susceptibility characterization steps.

Health inequalities associated with neighbourhood deprivation in the Quebec population with hypertension in primary prevention of cardiovascular disease.

INTRODUCTION: Although a number of studies look at prevalence, incidence, treatment, mortality and morbidity in relation to hypertension, few have taken into account the effect of residential neighbourhood on these health indicators in the population diagnosed with hypertension. OBJECTIVES: The objective of this study was to measure and compare prevalence, mortality, morbidity, use of medical resources and treatments in relation to the level of material and social deprivation of the area of residence, in a population with a diagnosis of hypertension in primary prevention for cardiovascular disease (CVD) in Quebec in 2006-2007. METHODS: This study is based on a secondary analysis of the medical administrative data of the Quebec health insurance board, the Régie de l'assurance maladie du Québec, for a cohort of 276 793 patients aged 30 years or older who had been diagnosed with hypertension in 2006 or 2007, but who did not have a known diagnosis of CVD. The health indicators adjusted for age and sex are prevalence, death, a cardiovascular event, physician visits, emergency department visits and use of antihypertensives. Twenty-five types of areas of residence were obtained by crossing the material and social deprivation quintiles. RESULTS: Compared with patients living in materially and socially advantaged areas, those living in deprived areas were at 46% higher risk of a cardiovascular event, 47% higher risk of being frequent emergency department visitors and 31% higher risk of being frequent users of a general practitioner's services, but 25% lower risk of being frequent users of medical specialists' services. Little or no variation was observed in the use of antihypertensives. CONCLUSION: This study reveals the existence, in a CVD primary prevention context, of large variations in a number of health indicators among hypertensive patients owing to the material and social deprivation of residential neighbourhood. It is therefore important to take the socioeconomic context into account when planning interventions to prevent CVDs and their consequences.

TITRE: Inégalités de santé associées à la défavorisation du secteur de résidence au sein de la population du Québec ayant reçu un diagnostic d'hypertension artérielle en prévention primaire des maladies cardiovasculaires. INTRODUCTION: Bien que plusieurs études traitent de la prévalence, de l'incidence, du traitement, de la mortalité et de la morbidité en lien avec l'hypertension artérielle (HTA), peu d'entre elles tiennent compte de l'influence des secteurs de résidence sur ces indicateurs de santé au sein de la population ayant reçu un diagnostic d'HTA. OBJECTIFS: L'objectif de cette étude était de mesurer et comparer la prévalence, la mortalité, la morbidité, l'utilisation des ressources médicales et les traitements selon le niveau de défavorisation matérielle et sociale du secteur de résidence au sein de la population ayant reçu un diagnostic d'HTA en prévention primaire des maladies cardiovasculaires (MCV) au Québec en 2006-2007. MÉTHODOLOGIE: Cette étude repose sur une analyse secondaire des données médico- administratives de la Régie de l'assurance maladie du Québec pour une cohorte de 276 793 patients de 30 ans et plus ayant reçu un diagnostic d'HTA en 2006 ou en 2007 mais sans diagnostic connu de MCV. Les indicateurs de santé ajustés pour l'âge et le sexe sont la prévalence, le décès, un événement cardiovasculaire, les consultations médicales, les consultations à l'urgence ainsi que l'utilisation d'antihypertenseurs. Vingt-cinq types de secteurs de résidence ont été obtenus par croisement des quintiles de défavorisation matérielle et sociale. RÉSULTATS: Par rapport aux patients vivant dans des secteurs favorisés matériellement et socialement, ceux vivant dans des secteurs défavorisés avaient 46 % plus de risque d'événement cardiovasculaire, 47 % plus de risque d'être de grands utilisateurs de l'urgence, 31 % plus de risque d'être de grands utilisateurs des services d'un omnipraticien, mais 25 % moins de risque d'être de grands utilisateurs des services de médecins spécialistes. Peu ou pas de variation n'a été observée quant à l'utilisation d'antihypertenseurs. CONCLUSION: Cette étude révèle l'existence, dans le cadre de la prévention primaire des MCV, d'importantes variations pour plusieurs indicateurs de santé chez des patients hypertendus en raison de la défavorisation matérielle et sociale de leur secteur de résidence. Il est donc important de tenir compte du contexte socioéconomique lors de la planification d'interventions visant à prévenir les maladies cardiovasculaires et leurs conséquences.

[Heparin-induced thrombocytopenia: recent data]. / Les thrombocytopénies induites par l'héparine: données récentes.

Despite less frequent, heparin-induced thrombocytopenia (HIT) remains a severe complication of treatment with heparin, and is important to diagnose and manage appropriately. HIT results from an atypical immune response to heparin, with the synthesis of IgG antibodies specific to heparin-modified platelet factor 4 (PF4) which activate platelets, leukocytes and the endothelium. This activation explains that low platelet count is associated with thrombotic events in 50% of patients. The diagnosis of HIT is sometimes evoked because of atypical manifestations (i.e. cutaneous necrosis, amnesia, hypotension or dyspnea following intravenous injection of heparin). Biological assays are always necessary to confirm HIT in case of clinical suspicion, and specific rapid tests are now available for detecting anti-PF4 antibodies. However, their specificity is poor and functional assays such as serotonin release assay or platelet aggregation test are often necessary. Argatroban that is a direct antithrombin drug can be used in patients with severe renal failure and will be preferred to danaparoid sodium in this situation. Fondaparinux is not licensed for treating confirmed HIT and can only be used in case of suspicion. The early detection of HIT is based on the monitoring of platelet count recommended in surgical patients receiving a low molecular weight heparin and in all patients treated with unfractionated heparin.

Binding of heparin-dependent antibodies to PF4 modified by enoxaparin oligosaccharides: evaluation by surface plasmon resonance and serotonin release assay.

BACKGROUND: The minimal structural requirements of low-molecular-weight heparins that determine the risk of developing heparin-induced thrombocytopenia (HIT) are not fully defined. OBJECTIVES: The ability of enoxaparin-derived oligosaccharides (OS) to induce platelet activation and exposure of platelet-factor 4 (PF4) epitopes recognized by antibodies developed in HIT was studied by surface plasmon resonance (SPR) and serotonin release assay. RESULTS: Decasaccharides with ≥ 11 sulfate groups induced platelet activation in the presence of plasma from patients with confirmed HIT. Serotonin release of > 80% without full inhibition at 100 µg mL(-1) was achieved with decasaccharides containing 14 or 15 sulfate groups, 2 dodecasaccharides and 2 tetradecasaccharides. An SPR method was developed using purified PF4 immobilized on carboxymethylated dextran. Antibodies from all HIT samples bound to PF4/heparin in SPR assays with resonance units (RU) ratio of 109-173 with HIT plasma vs. 88-93 with control plasma. RU ratios > 100 were measured when PF4 was pre-incubated with OS with ≥ 10 saccharide units and one octasaccharide containing 10 sulfate groups. RU ratios > 140, similar to those measured when PF4 was pre-incubated with unfractionated heparin or enoxaparin, were obtained with purified dodeca- and tetradecasaccharides. RU values strongly correlated with the number of sulfate groups in the decasaccharides tested (r = 0.93, P = 0.02). CONCLUSIONS: LMWHs with fragments > 10 saccharides and a large number of sulfate groups are more likely to be associated with a higher risk of HIT. These structure-activity relationships were independent of the ability of the OS to bind antithrombin.

Efficient characterization of the TCR repertoire in lymph nodes by flow cytometry.

Analysis of the T-cell receptor (TCR) repertoire by flow cytometry proved to be relevant for investigating T-cell diversity and detecting reactive cells in blood samples. We used this approach to characterize non-malignant T-lymphocytes in lymph nodes and give insights into their origin. The TCR repertoire of CD4+ and CD8+ T-cells from 81 lymph nodes was analyzed with a four-color flow cytometer using a wide panel of 25 anti-Vbeta monoclonal antibodies. Flow cytometry proved to be a useful and informative technique. We demonstrated a diversified TCR-Vbeta repertoire, and only low level expansions, in 53% of the samples. They involved nearly all Vbeta families, were more frequent in the CD8+ subset of older patients, but were not related to pathology. No evidence could be demonstrated in favor of stimulation by common antigens. Interestingly, the TCR-Vbeta repertoire proved to be very similar in lymph nodes and blood samples. Our results argue that in the cases studied, lymph node enlargement is mainly due to an increased homing of circulating T-cells. They also provide reference values for expression of 25 TCR-Vbeta in lymph nodes, which could serve as a basis for further applications in diagnosis of T-cell lymphoproliferative disorders.

Genetics and epigenetics of 1q rearrangements in hematological malignancies.

Recently, we and others have described a novel class of chromosome aberrations that involves constitutive heterochromatin on human chromosome 1 (cytogenetic band 1q12). These anomalies are particularly frequent in B cell non-Hodgkins lymphoma (NHL) and multiple myeloma (MM) and, remarkably, almost invariably involve partial or total gain of chromosome 1q (including 1q12 heterochromatin) and the formation of novel heterochromatin/euchromatin junctions. This review discusses the pathological significance of these anomalies in light of i) recent integrated gene expression and array comparative genomic hybridisation (aCGH) profiling in MM and ii) increasing evidence of a key role for heterochromatin in the control of normal and pathological gene silencing.

Clinical, cytogenetic and molecular characteristics of 14 T-ALL patients carrying the TCRbeta-HOXA rearrangement: a study of the Groupe Francophone de Cytogénétique Hématologique.

Recently, we and others described a new chromosomal rearrangement, that is, inv(7)(p15q34) and t(7;7)(p15;q34) involving the T-cell receptor beta (TCRbeta) (7q34) and the HOXA gene locus (7p15) in 5% of T-cell acute lymphoblastic leukemia (T-ALL) patients leading to transcriptional activation of especially HOXA10. To further address the clinical, immunophenotypical and molecular genetic findings of this chromosomal aberration, we studied 330 additional T-ALLs. This revealed TCRbeta-HOXA rearrangements in five additional patients, which brings the total to 14 cases in 424 patients (3.3%). Real-time quantitative PCR analysis for HOXA10 gene expression was performed in 170 T-ALL patients and detected HOXA10 overexpression in 25.2% of cases including all the cases with a TCRbeta-HOXA rearrangement (8.2%). In contrast, expression of the short HOXA10 transcript, HOXA10b, was almost exclusively found in the TCRbeta-HOXA rearranged cases, suggesting a specific role for the HOXA10b short transcript in TCRbeta-HOXA-mediated oncogenesis. Other molecular and/or cytogenetic aberrations frequently found in subtypes of T-ALL (SIL-TAL1, CALM-AF10, HOX11, HOX11L2) were not detected in the TCRbeta-HOXA rearranged cases except for deletion 9p21 and NOTCH1 activating mutations, which were present in 64 and 67%, respectively. In conclusion, this study defines TCRbeta-HOXA rearranged T-ALLs as a distinct cytogenetic subgroup by clinical, immunophenotypical and molecular genetic characteristics.

[CDKN2A gene mutation and loss of p16 protein activity in a patient on levodopa presenting sporadic multiple primary melanoma]. / Mutation du gène CDKN2A et perte d'activité de la protéine p16 chez un malade traité par L-Dopa et atteint de mélanomes sporadiques multiples.

BACKGROUND: Cutaneous melanoma is a complex disease involving genetic and environmental factors. Levodopa has been incriminated in the development and/or progression of melanoma. OBSERVATION: We report the case of a man treated with levodopa and a dopadecarboxylase inhibitor for Parkinson's disease and presenting 22 cutaneous melanomas over a 4-year period. The patient is of phototype II and presents multiple nevi. Genetic analysis of predisposing genes demonstrated a CDKN2A mutation with loss of p16 activity. DISCUSSION: Multiple melanomas may be associated with genetic predisposition, and screening for the latter should be performed. The exceptionally high number of melanomas developed by our patient raised suspicions about levodopa, a precursor in melanin synthesis, as a potential inducer. Increased dermatologic controls and screening for predisposing genetic factors appear to us to be warranted in the event of melanoma development in patients on levodopa.

[Genetic changes in chronic lymphocytic leukemia]. / Anomalies génétiques des leucémies lymphoides chroniques.

Chronic B-cell leukemias (CLL) are characterised by a striking cytogenetic signature composed of multiple recurrent chromosomal imbalances involving specific chromosomal regions i.e. 13q, 11q, 12q, 17p et 6q (decreasing order of frequency). These chromosomal aberrations may be found in up to 80% of the cases either as isolated or associated anomalies. They can also appear during the course of the disease suggesting their secondary nature. Furthermore, and at variance with other B-cell proliferations like lymphomas or myelomas, balanced translocations involving immunoglobulin (Ig) gene locus are rare. In addition to their interest in patient diagnosis and follow-up, these tumour-specific genetic markers also harbor important prognostic significance : isolated 13q deletions correlate with prolonged survival whereas both 17p and 11q partial deletions are independent predictors of rapid disease progression and short survival times in multivariate analyses. Genetic analyses as well as the first transcriptome studies of CLL reveal 1) a common mechanism of transformation and/or cell of origin, 2) the existence of at least two prognostic subgroups based on Ig mutational status.

Novel evidence of a role for chromosome 1 pericentric heterochromatin in the pathogenesis of B-cell lymphoma and multiple myeloma.

1q rearrangement is a remarkably frequent secondary chromosomal change in both non-Hodgkin's lymphoma (NHL) and multiple myeloma (MM), where it is associated with tumor progression. To gain insight into 1q rearrangement-associated disease mechanisms, we used fluorescence in situ hybridization (FISH) to search for recurring 1q breaks in 35 lymphoma samples (31 NHL patients and 4 lymphoma-derived cell lines) as well as 22 MM patients with cytogenetically determined 1q abnormalities. Strikingly, dual-color FISH analysis with chromosome 1 centromere and 1q12-specific probes identified constitutive heterochromatin band 1q12 as the single most frequent breakpoint site in both NHL and MM (39% and 89% of 1q breaks, respectively). These rearrangements consistently generated aberrant heterochromatin/euchromatin junctions and gain of 1q12 material. A further 30% of NHL 1q breaks specifically involved two other novel, closely spaced sites (clusters I and II) within a 2.5 Mb region of proximal 1q21 (D1S3620 to D1S3623). A possible association between these sites and NHL subtype was evident; the cluster I rearrangement was frequent in follicular and diffuse large cell lymphoma, whereas the cluster II rearrangement was more frequently observed in diffuse small-cell lymphoma (2/2 marginal zone lymphomas, 1/2 atypical chronic lymphocytic leukemias, and 1 lymphoplasmacytic lymphoma in this series). Candidate oncogenes bordering this interval (BCL9 and AF1Q) were not rearranged in any patient except one (AF1Q). This study provides the first evidence of involvement of 1q12 constitutive heterochromatin in the pathogenesis of NHL and MM and indicates proximal 1q21 to be of specific pathological significance in NHL.

Hypodiploidy is a major prognostic factor in multiple myeloma.

Conventional karyotypes performed before any treatment in 208 patients with multiple myeloma were reviewed by the Groupe Français de Cytogénétique Hématologique. A total of 138 patients displayed complex chromosomal abnormalities (CCAs). According to the chromosome number pattern, a first group of 75 patients had a hyperdiploid karyotype. A second group of 63 patients referred to as the hypodiploid group had either pseudodiploid, hypodiploid, or near-tetraploid karyotypes. Of 159 treated patients available for survival analysis, 116 had an abnormal karyotype. The comparison of overall survival (OS) between hyperdiploid and hypodiploid patients showed a highly significant difference (median OS 33.8 vs 12.6 months, respectively, P <.001). The presence of 14q32 rearrangements (36 of 116 patients) worsened the prognosis (median OS 17.6 vs 29.9 months, P <.02). The presence of chromosome 13q abnormalities (13qA, 63 patients) did not modify OS in CCA patients (median OS 20.6 vs 27.8 months, P <.59). However, taking into account the whole series including normal karyotypes, 13qA (63 of 159 patients) had a significant impact on OS (median 20.6 vs 37.1 months, P <.04). In the same way, the presence of a hypodiploid karyotype (52 of 159 patients) had a strong prognostic value (OS 12.8 vs 44.5 months, P <.000 01). A multivariate analysis including stage, beta2-microglobulin, bone marrow plasmocytosis, treatment type, 13qA, and hyperdiploidy and hypodiploidy showed that a hypodiploid karyotype was the first independent factor for OS (P <.001), followed by treatment approach. These results confirm that the chromosome number pattern of malignant plasma cells is a very powerful prognostic factor in newly diagnosed multiple myeloma patients.

Dag-1 carcinoma cell in studying the mechanisms of progression and therapeutic resistance in bladder cancer.

OBJECTIVE: We describe a new human bladder carcinoma cell line (DAG-1) established from a resected bladder cancer fragment and maintained in culture for more than 5 years and over 300 passages. METHODS AND RESULTS: Immunological, biochemical and molecular analysis showed that the DAG-1 cells (62 chromosomes) express the cytokeratines 8, 13, 18 and 20 that confirm their epithelial origin as well as numerous cytokine and cytokine receptor mRNAs. They secrete tissue-type plasminogen activator (t-PA), urokinase-type plasminogen activator (u-PA), plasminogen activator inhibitors (PAI-1 and PAI-2), and express u-PA receptors (u-PAR/CD87) at their surface. DAG-1 cells are resistant to TNFalpha- and IFNgamma-induced apoptosis, two cytokines secreted in the urine of Calmette-Guérin bacillus-treated patients and involved in the tumor regression. CONCLUSION: The DAG-1 cell line is a useful tool, both in vitro and in vivo, to study the progression of bladder tumors and their mechanisms of resistance to immunotherapy in relation with PAI-2 and antioxidant enzymes.

The IgG Fc receptor, FcgammaRIIB, is a target for deregulation by chromosomal translocation in malignant lymphoma.

Rearrangement of chromosomal bands 1q21-23 is one of the most frequent chromosomal aberrations observed in hematological malignancy. The genes affected by these rearrangements remain poorly characterized. Typically, 1q21-23 rearrangements arise during tumor evolution and accompany disease-specific chromosomal rearrangements such as t(14;18) (BCL2) and t(8;14) (MYC), where they are thus thought to play an important role in tumor progression. The pathogenetic basis of this 1q21-23-associated disease progression is currently unknown. In this setting, we surveyed our series of follicular lymphoma for evidence of recurring 1q21-23 breaks and identified three cases in which a t(14;18)(q32;q21) was accompanied by a novel balanced t(1;22)(q22;q11). Molecular cloning of the t(1;22) in a cell line (B593) derived from one of these cases and detailed fluorescent in situ hybridization mapping in the two remaining cases identified the FCGR2B gene, which encodes the immunoreceptor tyrosine-based inhibition motif-bearing IgG Fc receptor, FcgammaRIIB, as the target gene of the t(1;22)(q22;q11). We demonstrate deregulation of FCGR2B leading to hyperexpression of FcgammaRIIb2 as the principal consequence of the t(1;22). This is evidence that IgG Fc receptors can be targets for deregulation through chromosomal translocation in lymphoma. It suggests that dysregulation of FCGR2B may play a role in tumor progression in follicular lymphoma.

Role of autologous CD4+ T cell clones in human B non-Hodgkin's lymphoma: aborted activation and G1 blockade induced by cell-cell contact.

This article describes the study of the functional relationship between auto-tumor-reactive CD4(+) T cell clones (TCC) and autologous malignant B cells. Four auto-tumor-reactive CD4(+) TCC were derived from tumor-infiltrating T lymphocytes (TIL-T) from a freshly isolated human follicular lymphoma by the following technique: total CD4(+) TIL-T were negatively purified by an immunomagnetic procedure, then CD4(+) TCC were obtained by limiting dilution in the presence of IL-2 and autologous non-irradiated follicular lymphoma cells as feeders. After expansion, these CD4(+) TCC were co-cultured with non-irradiated autologous malignant B cells. All four TCC were activated by B lymphoma cells and proliferated, as assessed by CD25 expression and cell cycle analysis. Activation and proliferation of B lymphoma cells were studied in response to activated CD4(+) T cells. Although all four TCC were able to induce B lymphoma cell activation (Ki-67 antigen induction and CD40 up-regulation), cells were subsequently blocked in G1 phase. Activation of B-NHL cells was mediated by TCR-HLA class II interaction, as shown by a blocking experiment using an anti-CD4 monoclonal antibody (mAb). Since anti-CD40 mAb with or without IL-4 did not induce proliferation of B lymphoma cells in contrast to normal B cells, we suggest that the blockade in G1 phase is due to the presence of abnormalities in B lymphoma cells. This is the first evidence that autologous reactive CD4(+) TCC can engage follicular lymphoma B cells to enter the cell cycle and induce an aborted activation stage.

Interphase FISH: a rapid method for detecting malignant plasma cells in multiple myeloma patients submitted to autologous transplantation.

Fluorescence in situ hybridization (FISH) on interphase nuclei has been shown to be an efficient method for detecting aneuploidy in multiple myeloma (MM). The aim of this study was to test the feasibility of FISH techniques for detecting malignant cells in the harvests of MM patients submitted to autologous transplantation. As trisomy 9 (T9) is a frequent event in MM, we used it as a genetic marker of malignant plasma cells. T9 was detected in 45 out of 55 MM bone marrow samples (81.8%) using a chromosome 9 centromeric (C9C) probe. Twenty-four of the 55 MM patients were subjected to high-dose therapy followed by autologous unselected progenitor cell transplantation. Trisomy 9 was detected in 20 patients and was used as a marker of malignant cells. Upon karyotypic analysis, three of the four remaining patients without T9 showed an unbalanced translocation leading to a complete trisomy of the long arm of chromosome 1 (T1q). We thus used a 1q juxtacentromeric probe, pUC1.77, as another genetic marker of malignant plasma cells in these three further patients. FISH with C9C or pUC1.77 probes was performed on the harvests of these 23 patients and detected clonal cells in 11 transplants. The disease-free survival from graft was significantly longer for the patients who had no malignant cells in their transplant (P=0.009). The median disease-free survival was 23 months in these patients, as compared to 12 months in the patients whose transplant was contaminated. As almost all MM are cytogenetically abnormal, FISH with adequate probes represents a simple, quantitative tool for rapid detection of malignant cells in the harvests. Our results also suggest that the presence of MM cells in the transplant may be predictive of poor outcome.