CD40-ligand stimulates myelopoiesis by regulating flt3-ligand and thrombopoietin production in bone marrow stromal cells.

CD40 ligand (CD40L)/CD40 interactions play a central role in T-cell-dependent B-cell activation as previously shown by in vitro studies, the phenotype of CD40L knockout mice and the defective expression of CD40L in patients who have X-linked immunodeficiency with hyper-IgM. The distribution of CD40 in cells other than of myeloid and lymphoid lineages has suggested additional functions for this receptor/ligand couple. Here we show that CD40L stimulates myelopoiesis with a noticeable effect on megakaryocytopoiesis in cocultures of hematopoietic progenitor cells and bone marrow stromal cells. These results suggest a mechanism by which T-cell or platelet-associated or soluble CD40L may regulate myelopoiesis. (Blood. 2000;95:3758-3764)

Expression of glypican-1, syndecan-1 and syndecan-4 mRNAs protein kinase C-regulated in rat immature Sertoli cells by semi-quantitative RT-PCR analysis.

In seminiferous tubules, Sertoli cells provide structural and nutritional support for the developing germinal cells. Cell to cell signalization and cell adhesion require proteoglycans expressed at the cell membrane. A preliminary biochemical and structural approach indicated that cell surface proteoglycans are mostly heparan sulfate (HSPG) in immature rat Sertoli cells. The present study focused on the qualitative and quantitative expression of three membrane HSPG, syndecan-1, syndecan-4 and glypican-1 in Sertoli cells of 20-day-old rat. A semi-quantitative multiplex RT-PCR strategy was developed to appreciate the effect of PKC activation on the mRNA expression of the three HSPG. Our data show that the syndecan-1 and glypican-1 mRNA expression is increased by the phorbol myristate acetate (PMA) suggesting a regulation of their expression by the phosphatidyl inositol pathway, as previously hypothesized (Fagen et al., Biochim. Biophys. Acta, 1472 (1999) 250-261). In addition, a physiological effector of the PKC as ATP gave similar effects. Thus, this over-expression could be related with paracrine factors secreted by germ cells.

hxc2, an Arabidopsis mutant with an altered hypersensitive response to Xanthomonas campestris pv. campestris.

A chemical mutagenized population of Arabidopsis Col-0-gl plants was screened for an altered hypersensitive response (HR) after spray inoculation with an HR-inducing isolate of Xanthomonas campestris pv. campestris (strain 147). Three classes of mutant were identified: those exhibiting an HR- phenotype or partial loss of HR; hyper-responsive mutants showing necrotic lesions rapidly leading to the collapse of leaves; and susceptible mutants. One mutant belonging to the susceptible class, hxc-2, was extensively characterized. The compatible phenotype observed several days after initiation of the interaction was confirmed by measurement of in planta bacterial growth and use of bacterial strains constitutively expressing the GUS reporter gene. In the same way, accumulation of autofluorescent compounds, salicylic acid production and defence gene expression in the mutant were found to be similar to that displayed by the susceptible ecotype. Inoculation of hxc-2 with different avirulent bacteria suggests that the mutation is specific for the interaction with the Xcc 147 strain, although the mutation has been shown to affect a single dominant locus, different from the resistance locus defined by genetic analysis of resistance to Xcc 147. Genetic mapping of the mutation indicated that it is located on chromosome III, defining a previously unknown resistance function in response to X. c. campestris.

[Interventional MRI. Analysis of data and prospects]. / IRM interventionnelle. Analyse de données et perspectives.

In spite of its many advantages: 3D imaging, improved tissue characterization, and lack of ionizing radiation, interventional MRI remains seldom used. Several factors are involved. The purpose of this paper is to analyze the factors preventing or slowing the development of this technique based on a review of data from the literature, work presented at the second symposium on interventional MRI (Düsseldorf, 1997), and our own experimental data. The following elements will be discussed: difficulties related to image quality and open magnets, control of targeted image acquisitions, MR environment and problems related to asepsis, as well as advances of other techniques. Finally, short-term and mid-term perspectives will be presented. These are related to the goals of the technique: open or short bore closed magnets? MR unit installed in a radiology department? MR unit dedicated to interventional procedures only or mixed diagnostic-interventional unit? interventional MR unit placed in a neurosurgery operating room? interventional MR unit installed in a general surgery operating room?

Sodium chlorate induces undersulfation of cellular proteoglycans and increases in FSH-stimulated estradiol production in immature rat Sertoli cells.

The functional influence of cell proteoglycan (PG) undersulfation on estradiol synthesis by immature rat Sertoli cell cultures was investigated by using sodium chlorate, an inhibitor of the active sulfate donor for sulfotransferases. The addition of sodium chlorate to 20-day-old rat Sertoli cell cultures abolished [35S]-sulfate incorporation into neosynthesized PG and consequently reduced the residence time of undersulfated PG in cell membrane. Simultaneously, follicle-stimulating hormone (FSH)-stimulated estradiol synthesis was increased by 45%. The effects of sodium chlorate upon Sertoli cell PG synthesis and steroidogenesis were not reproduced with the addition of sodium chloride. Addition of phosphodiesterase inhibitors (MIX or Ro20-1724) decreased the magnitude of the chlorate effect on FSH-stimulated steroidogenesis, suggesting that part of chlorate's effect on steroidogenesis resulted from a decrease in adenosine cyclic 3',5'-phosphate (cAMP)-specific phosphodiesterase activity. Additionally, chlorate 1) increased Sertoli cell steroidogenesis at a step located beyond cAMP (restricted to Sertoli cell cultures exhibiting moderate steroidogenic response to (Bu)2cAMP) and 2) abolished the inhibition of steroidogenesis induced by transforming growth factor-beta. These results support our previous data, which showed that alteration in PG synthesis and the consequent decrease in cell membrane PG content induce an increase in FSH-stimulated estradiol synthesis in Sertoli cell cultures. The identification of cAMP-specific phosphodiesterase activity as a signal transduction step modified by PG undersulfation suggests the possible involvement of cell PG in the regulation of phosphodiesterase activity and, therefore, of FSH responsiveness during testicular development.

Differential activation of two ACC oxidase gene promoters from melon during plant development and in response to pathogen attack.

ACC (1-aminocyclopropane-1-carboxylate) oxidase genes are differentially expressed in melon during development and in response to various stresses. We investigated the molecular basis of their transcription by analyzing the 5' untranslated regions of the ACC oxidase genes CM-ACO1 and CM-ACO3. In order to determine how their temporal and spatial expression patterns were established, we fused the promoter regions of CM-ACO1 (726 bp) and CM-ACO3 (2260 bp) to the beta-glucuronidase (GUS) reporter gene and examined their regulation in transgenic tobacco plants. The CM-ACO1 promoter was able to drive GUS expression in response to wounding, and to treatment with ethylene or copper sulfate. It was also rapidly induced (8-12 h postinoculation) in tobacco leaves inoculated with the hypersensitive response (HR)-inducing bacterium Ralstonia solanacearum. Expression was also observed during compatible interactions but was delayed. In contrast, the CM-ACO3 promoter was not expressed in response to infection, but was up-regulated during flower development. Both promoters were regulated during leaf senescence but in different patterns. The CM-ACO1-driven GUS activity increased sharply concomitantly with the onset of chlorophyll breakdown, while the CM-ACO3 promoter drove strong GUS expression in green, fully expanded leaves and this declined at the onset of senescence. This result is consistent with the expression patterns of these two genes in senescent melon leaves. These data suggest that the regulation of expression of CM-ACO1 is related preferentially to stress responses, whereas CM-ACO3 seems to be associated with developmental processes. The possible role of ethylene is discussed, particularly in the regulation of the CM-ACO1 gene in response to stress and during senescence.

[Cohabiting, decohabiting, and recohabiting: the routes followed by two generations of women]. / Cohabiter, decohabiter, recohabiter: itineraires de deux generations de femmes.

PIP: The process of leaving the parental home on reaching adulthood is analyzed using data for two cohorts of French women, those born in 1947 and those born in 1959, who were surveyed in 1986. Two alternative ways of establishing adulthood are considered, namely, marriage and the achievement of an academic or professional qualification. The tendency of unmarried adult women to return to the family home is considered. (SUMMARY IN ENG AND GER AND SPA)^ieng

[Aneurysm formation on dacron prosthesis after 84 months of use. Pathology, structural and chemical evaluation of the explanted device (author's transl)]. / Formation anévrismale sur prothèse artérielle synthétique. Analyse pathologique, structurale et chimique d'une greffe en polyester après 84 mois d'implantation.

A 56 year old patient fitted with a femoro-popliteal Dacron prosthesis (Weavenit-Meadox Medical) 84 months earlier, presented with a severe palpable dilation in the middle part of the graft. The dilated segment of the prosthesis was resected locally and spliced to a new fabric device. The explanted section of prosthesis was analyzed; the dilation was found to extend only over several centimeters near the centre of the prosthesis. The degree of "healing" was found to be satisfactory except in the part which was most distended; this area also revealed mild bacterial colonization. Physico-chemical analysis of the fabric revealed that the dilation had taken place subsequently to hydrolytic degradation of the polyester fibres. Manufacturing conditions may have contributed to predisposing parts of the prosthesis to accelerated biodeterioration in vivo.