Retrovirus-mediated gene transfer of the human multidrug resistance-associated protein into hematopoietic cells protects mice from chemotherapy-induced leukopenia.

Utilization of chemotherapy for the treatment of tumors is mainly limited by its hematological toxicity. Because of the low-level expression of drug resistance genes, transduction of hematopoietic progenitors with multidrug resistance 1 (MDR1) or multidrug resistance-associated protein (MRP) genes should provide protection from chemotherapeutic agent toxicity. Successful transfer of drug resistance genes into hematopoietic cells may allow the administration of higher doses of chemotherapy and, thus, increase regression of chemosensitive tumors. The interest in the use of MRP as an alternative to MDR1 for bone marrow protection lies in its different modulation. This would allow, in the same patient, the use of MDR1 reversal agents to decrease MDR1 tumor resistance without reversing bone marrow (BM) protection of the MRP-transduced hematopoietic cells, since MRP expression is not reversed by these agents. We have constructed MRP-containing retroviral vectors using the phosphoglycerate kinase promoter and generated ecotropic producer cells. Lethally irradiated mice were engrafted with BM cells transduced by coculture with MRP producer cells. Evidence of long-term (9 months) gene transfer was provided by PCR of peripheral blood from MRP-transduced mice. Southern blot analysis confirmed the integrity of the provirus in the MRP-transduced mice. Long-term MRP expression (>5 months) was detected by RT-PCR and fluorescence-activated cell sorting of blood from living mice. High-level expression of MRP in murine hematopoietic cells reduces doxorubicin-induced leukopenia and mortality. Furthermore, we show in vivo selection of MRP-transduced cells following doxorubicin administration, with better and more significant chemoprotection after the second chemotherapy cycle. These data indicate that MRP retroviral gene transfer may be useful for chemoprotection and selection.

[Left ventricular diastolic function: value of its study with mitral and pulmonary venous Doppler phonocardiography and apexography]. / La fonction diastolique ventriculaire gauche: intérêt de son étude par le doppler mitral, le doppler veineux pulmonaire, le phonocardiogramme et l'apexogramme.

The study of mitral flow and pulmonary venous flow by Doppler provides a non-invasive method of assessing diastolic function. But there are difficulties in differentiating normal pattern from "pseudo-normal" (Appleton Type II) (E/A Mitral > 1). Phonocardiography enables the recording of early (B3) and late (B4) diastolic gallops. The apexogramme enables calculation of the a/H and D/H ratios (amplitude of the "D" wave resulting from rapid early diastolic filling to the total amplitude of the apexogramme). These two techniques record pulsatile phenomena ("pulse waves") arising from variations in intra-left ventricular pressure. They may complete the interpretation of Doppler recordings of velocities of blood flow ("flow waves"). To evaluate the value of each technique, the authors studied left ventricular diastolic function by Doppler phonocardiography and apexography in 60 subjects (38 patients of which 30 with ischaemic heart disease, and 22 healthy subjects). The results showed that increase in velocity and deceleration slope of the Doppler mitral E wave was associated with the presence of a B3 and correlated (r = 0.60; p = 0.0001) with the D/H ratio of the apexogramme. On the other hand, the absence of correlation between the mitral A wave velocity and a B4 associated with an increased a/H ratio enables the differentiation of normal Doppler mitral flow (absence of B4, Doppler a/H ratio < 12%) from pseudo-normal appearances (B4, a/H ratio > 12%). Therefore, the evaluation of diastolic function by Doppler mitral and pulmonary venous flow analysis may be usefully completed by phonocardiography and apexography.

Embryotoxicity of human sera from patients treated with isotretinoin.

Sera of 20 patients treated with 20-40 mg isotretinoin/day were tested for embryotoxicity potential. For each patient, the first sample was taken before treatment (control sample) and the second was taken 2 months after the start of treatment (treated sample). Six embryos displaying six or seven pairs of somites were cultured for 26 hr in each serum sample, when sufficient serum was available. No deaths were observed in the control sample, whereas dead embryos (6%) were observed in the treated sample. The rates of malformed embryos were 13 and 81% in the control and in the treated sample, respectively. The most frequent abnormalities affected the cephalic neural tube, the branchial bars, the yolk sac circulation and the caudal neural tube. Growth and differentiation were significantly decreased in the treated sample. The concentrations of isotretinoin and of two metabolites (trans-retinoic acid and 4-oxo-isotretinoin) were measured in 12 sera. A correlation between embryotoxicity and concentration was established for two of the chemicals. Modulation of the embryotoxicity by drug-induced changes in the serum cannot be excluded.