SP/drug efflux functionality of hematopoietic progenitors is controlled by mesenchymal niche through VLA-4/CD44 axis.

Hematopoiesis is orchestrated by interactions between hematopoietic stem/progenitor cells (HSPCs) and stromal cells within bone marrow (BM) niches. Side population (SP) functionality is a major characteristic of HSPCs related to quiescence and resistance to drugs and environmental stresses. At steady state, SP cells are mainly present in the BM and are mostly absent from the circulation except in stress conditions, raising the hypothesis of the versatility of the SP functionality. However, the mechanism of SP phenotype regulation is unclear. Here we show for the first time that the SP functionality can be induced in lin(-) cells from unmobilized peripheral blood after nesting on mesenchymal stromal cells (MSCs). This MSC-induced SP fraction contains HSPCs as demonstrated by their (i) CD34(+) cell percentage, (ii) quiescent status, (iii) in vitro proliferative and clonogenic potential, (iv) engraftment in NSG (NOD SCID gamma chain) mice and (v) stemness gene expression profile. We demonstrate that SP phenotype acquisition/reactivation by circulating lin(-) cells is dependent on interactions with MSCs through VLA-4/α4ß1-integrin and CD44. A similar integrin-dependent mechanism of SP phenotype acquisition in acute myeloid leukemia circulating blasts suggests an extrinsic regulation of ATP-binding cassette-transporter activity that could be of importance for a better understanding of adhesion-mediated chemoresistance mechanisms.

[Infectious endocarditis in cerebral death: implications for explantation of tissues and organs]. / Endocardite infectieuse chez les patients en état de mort cérébrale: implications pour le prélèvement de tissus et d'organes.

Allograft valve replacement is the preferred treatment for infectious endocarditis With severe annular destruction. Explantation of the valve in patients with cerebral death requires preliminary cardiac investigations and strict surgical procedures. The authors report two cases of right atrial endocarditis discovered at the time of explantation of the valvular allografts. In view of the infectious nature of the lesions, no tissues were resected. In both cases, transthoracic echocardiography had not diagnosed these lesions. The sensitivity of transoesophageal echocardiography in the diagnosis of these lesions should lead to systematic referral for this investigation. The infectious nature of these endocarditic lesions should raise suspicion about the presence of a central venous catheter. In addition, careful inspection of the chambers, septa and cardiac valves should be performed at surgery. The detection of potentially infectious endocarditic lesions should, in accordance with present recommendations, lead to renouncing the explantation of valvular allografts.

[Cardiac lymphoma disclosed by ischemic accident. A case report]. / Lymphome cardiaque révélé par un accident ischémique. A propos d'un cas.

We report on the detection of a primitive cardiac lymphoma revealed by a cerebral vascular accident in a context of deterioration of the general state with fever. The diagnosis of the cerebral vascular accident was verified by the brain scan. The echocardiography, in particular the transesophageal ultrasound, suggested the diagnosis of cardiac lymphoma due to the existence of an inhomogeneous multilobar mass invading the right ventricle and largely encompassing the right auricle. The histologic diagnosis of a malignant non-Hodgkin's lymphoma of type B malignancy was confirmed by anatomopathology. The evolution was, unfortunately, rapidly unfavorable, with the patient dying in a state of cerebral suffering despite a combination treatment of chemotherapy and radiotherapy.

Visualization of myocardial infarction six hours after injection of 111 In-antimyosin antibodies using an image subtraction technique.

111 In-antimyosin antibodies are capable of visualizing acute myocardial infarction (MI). Because of slow blood clearance, images are usually recorded 24 or 48 h postinjection. This pilot study was aimed at validating a blood pool subtraction technique, which makes it possible to visualize MI 6 h postinjection. Twenty-five patients with proven MI (16 anterior, 9 inferior) were imaged 10 minutes, 6 and 24 h after an injection of 110 MBq 111 In-labelled antimyosin antibodies, with a mean delay of two weeks after infarction. Three planar views were obtained each time. Using software which performs geometric registration, grey level normalization and subtraction of images, the blood pool image (obtained 10 minutes postinjection) was subtracted from the 6 hour image. The resulting image was the blood pool corrected 6 h image. The 24 h images and the blood pool corrected 6 h images were interpreted blindly and the number of correct, incorrect and indeterminate MI localizations were tabulated. The number of correct localizations was 19/25 for the standard 24 h images and 22/25 for the blood pool corrected 6 h images. With this blood pool subtraction method it was possible to visualize MI 6 h postinjection. Theoretically, this method could be applied six hours after myocardial infarction.

[Value of transesophageal echography in the detection of left intraventricular masses. Apropos of a case of apical thrombus]. / Intérêt de l'échographie transoesophagienne biplan dans la détection des masses intra-ventriculaires gauches. A propos d'une observation de thrombus apical.

The authors report a case of left intraventricular thrombus investigated by two-dimensional transesophageal echocardiography (TEE). Three longitudinal views obtained by rotation, left lateral inclination and by advancing the probe, enabled the precise evaluation of a mass situated at the apex of the left ventricle, together with ventricular morphology and kinetics. Two-dimensional TEE is electively indicated for confirmation of the diagnosis of left intraventricular apical masses, in particular in hypoechogenic patients and to guide possible surgery. The two-plane probe provides a certain number of sections which remain relatively limited but this problem is resolved with the development of multidimensional probes.

[Dynamic telethermography in E.N.T. cancerology]. / Approche de la télé-thermographie dynamique en cancérologie O.R.L.

Thermography is used in human pathology to capture and visualise infra-red rays emitted directly and spontaneously by the human body. The author first describes the main techniques of thermography, their indications their advantages and their potential problems:--contact thermography;--static thermography; --dynamic telethermography. The information provided by the latter in the case of E.N.T. and cervico-facial malignancies should be interpreted with caution and only as a complement to other investigations such as radiography, echography and isotope studies. The following features are seen: --the low value of cerevical hyperthermia in relation to lymphadenopathies, due to the "thermal interference" of the great vessels of the neck; --the contrast between large lymphadenopathies which are often quite cold in comparison with small lymphadenopathies which are always hot; --the value of the method in determining extension of a skin tumour, for the surveillance of areas already tready by surgery or physical agents, in seeking and discovering an endo-cavitray neoplastic zone or a bone metastasis.