High-dose chemotherapy and peripheral blood stem cell support in refractory gestational trophoblastic neoplasia

We present retrospectively our experience in the use of high-dose chemotherapy and haematopoietic stem cell support (HSCS) for refractory gestational trophoblastic neoplasia (GTN) in the largest series so far reported. In all, 11 patients have been treated at three Trophoblast Centres between 1993 and 2004. The conditioning regimens comprised either Carbop-EC-T (carboplatin, etoposide, cyclophosphamide, paclitaxel and prednisolone) or CEM (carboplatin, etoposide and melphalan) or ICE (ifosfamide, carboplatin, etoposide). Two patients had complete human chorionic gonadotrophin responses, one for 4 and the other for 12 months. Three patients had partial tumour marker responses for 1–2 months. High-dose chemotherapy and HSCS for GTN is still unproven. Further studies are needed, perhaps in high-risk patients who fail their first salvage treatment

Metabolic engineering of the iodine content in Arabidopsis

Plants are a poor source of iodine, an essential micronutrient for human health. Several attempts of iodine biofortification of crops have been carried out, but the scarce knowledge on the physiology of iodine in plants makes results often contradictory and not generalizable. In this work, we used a molecular approach to investigate how the ability of a plant to accumulate iodine can be influenced by different mechanisms. In particular, we demonstrated that the iodine content in Arabidopsis thaliana can be increased either by facilitating its uptake with the overexpression of the human sodium-iodide symporter (NIS) or through the reduction of its volatilization by knocking-out HOL-1, a halide methyltransferase. Our experiments show that the iodine content in plants results from a balance between intake and retention. A correct manipulation of this mechanism could improve iodine biofortification of crops and prevent the release of the ozone layer-threatening methyl iodide into the atmosphere

CD34+CD38+CD19+ as well as CD34+CD38-CD19+ cells are leukemia-initiating cells with self-renewal capacity in human B-precursor ALL.

The presence of rare malignant stem cells supplying a hierarchy of malignant cells has recently been reported. In human acute myelogenous leukemia (AML), the leukemia stem cells (LSCs) have been phenotypically restricted within the CD34+CD38- fraction. To understand the origin of malignant cells in primary human B-precursor acute lymphocytic leukemia (B-ALL), we established a novel in vivo xenotransplantation model. Purified CD34+CD38+CD19+, CD34+CD38-CD19+ and CD34+CD38-CD19- bone marrow (BM) or peripheral blood (PB) cells from three pediatric B-ALL patients were intravenously injected into sublethally irradiated newborn NOD/SCID/IL2rgamma(null) mice. We found that both CD34+CD38+CD19+ and CD34+CD38-CD19+ cells initiate B-ALL in primary recipients, whereas the recipients of CD34+CD38-CD10-CD19- cells showed normal human hematopoietic repopulation. The extent of leukemic infiltration into the spleen, liver and kidney was similar between the recipients transplanted with CD34+CD38+CD19+ cells and those transplanted with CD34+CD38-CD19+ cells. In each of the three cases studied, transplantation of CD34+CD38+CD19+ cells resulted in the development of B-ALL in secondary recipients, demonstrating self-renewal capacity. The identification of CD34+CD38+CD19+ self-renewing B-ALL cells proposes a hierarchy of leukemia-initiating cells (LICs) distinct from that of AML. Recapitulation of patient B-ALL in NOD/SCID/IL2rgamma(null) recipients provides a powerful tool for directly studying leukemogenesis and for developing therapeutic strategies

Human cord blood- and bone marrow-derived CD34+ cells regenerate gastrointestinal epithelial cells.

In the present study, we aimed to clarify the capacity of human cord blood- and bone marrow-derived progenitor cells to generate gastrointestinal epithelial cells in clinical and experimental transplantation settings. First, in a clinical transplantation setting, gastrointestinal tissues derived from female pediatric or juvenile recipients of allogeneic sex-mismatched bone marrow and cord blood transplantation were examined for the presence of donor-derived epithelial cells. Gastrointestinal specimens of allogeneic recipients included Y chromosome+ cytokeratin+ epithelial cells at a frequency of 0.4-1.9%. To further determine the capacity of purified human progenitor cells, human cord blood- or bone marrow-derived CD34+ cells were transplanted into newborn NOD/SCID/beta2-microglobulin(null) mice as an experimental transplantation assay. When gastrointestinal tissues derived from recipient mice were subjected to FISH and immunofluorescence analyses, human epithelial cells were identified at a frequency of 0.24-0.58% at 3 months posttransplantation. Finally, double FISH analyses using species-specific probes revealed that human chromosome+ epithelial cells did not possess any murine chromosomes, indicating that donor-derived epithelial cells were not generated only by cell fusion. On the basis of these findings, it is concluded that purified human cord blood and bone marrow CD34+ progenitor cells can generate gastrointestinal epithelial cells across allogeneic and xenogeneic histocompatibility barriers

Argentation TLC of ¹⁴C-labelled methyl esters of cell wall mycolic acids (MAMES) extracted from the Δ<i>MsdesA1</i> mutant grown in the presence or absence of acetamide.

<p>(A) Direction-I separated in petroleum ether:acetone (95:5, v/v); direction-II separated thrice in AgNO₃ treated silica gel in petroleum ether:ethyl acetate (9:1, v/v). The cyclopropanated derivative is indicated as X₁ and the faster-migrating species that co-migrated with α-MAMES in direction-I are indicated as X₂. The clear ‘imprint’ appearing superimposed on the comet shaped X₂ spot in the 8h –acetamide TLC is likely due to unlabelled α₂ mycolates synthesised at the early stages of DesA1 depletion. (B) Bar graph showing the relative amounts of each ¹⁴C-labelled mycolate subspecies indicated as a percentages of the total amounts of ¹⁴C-labelled mycolic acids detected on the TLC plates, as determined by densitometry.</p

Identification of a Desaturase Involved in Mycolic Acid Biosynthesis in <i>Mycobacterium smegmatis</i>

<div><p>Mycolic acids are unique long chain fatty acids found in the cell walls of mycobacteria including the tubercle bacillus, <i>Mycobacterium tuberculosis</i>. The introduction of double bonds in mycolic acids remains poorly understood, however, genes encoding two potential aerobic desaturases have been proposed to be involved in this process. Here we show that one of these genes, <i>desA1</i>, is essential for growth of the saprophytic <i>Mycobacterium smegmatis</i>. Depletion of <i>desA1</i> in a <i>M</i>. <i>smegmatis</i> conditional mutant led to reduction of mycolic acid biosynthesis and loss of viability. The DesA1-depleted cells exhibited two other phenotypes: using ¹⁴[C]-labelling, we detected the accumulation of minor mycolic acid-related species that migrated faster in a silver TLC plate. Spiral Time of Flight Mass Spectroscopic analysis suggested the presence of species with sizes corresponding to what were likely monoenoic derivatives of α-mycolic acids. Additionally, conditional depletion led to the presence of free fatty acyl species of lengths ~C₂₆-C₄₈ in the lysing cells. Cell viability could be rescued in the conditional mutant by <i>Mycobacterium tuberculosis desA1</i>, highlighting the potential of <i>desA1</i> as a new drug target in pathogenic mycobacteria.</p></div