Catherine Dubois

Voluntary Interruption of Pregnancy with Mifepristone (RU 486) and a Prostaglandin Analogue: A Large-Scale French Experience

In 2115 women seeking voluntary termination of pregnancy after 49 days of amenorrhea or less, we studied the effect of a single 600-mg dose of mifepristone (RU 486), followed 36 to 48 hours later by the administration of one of two prostaglandin analogues, either gemeprost (1 mg by vaginal suppository) or sulprostone (0.25, 0.375, or 0.5 mg by intramuscular injection). The women were monitored for four hours after prostaglandin administration. Efficacy was indicated by the complete expulsion of the conceptus without the need of an additional procedure. All other results were considered failures, and the pregnancy was then terminated by a surgical method. The overall efficacy rate was 96.0 percent (95 percent confidence interval, 95.0 to 96.8). The failures included persisting pregnancies (1.0 percent), incomplete expulsions (2.1 percent), and the need for hemostatic procedure (0.9 percent). The mean time to expulsion was significantly shorter when sulprostone was given in the high dose (4.5 hours) than when it was given in the two lower doses (13.1 and 19.3 hours) or when gemeprost was given (22.7 hours). The mean duration of uterine bleeding was 8.9 days (range, 1 to 35); one woman received a blood transfusion. Most women had transient abdominal pain after receiving prostaglandin, but there were few other side effects. We conclude that the administration of mifepristone followed by a small dose of a prostaglandin analogue is an effective and safe method for the early termination of pregnancy.

The F3 neuronal glycosylphosphatidylinositol-linked molecule is localized to glycolipid-enriched membrane subdomains and interacts with L1 and fyn kinase in cerebellum.

Abstract: The F3 molecule is a member of the immunoglobulin superfamily anchored to plasma membranes by a glycosylphosphatidylinositol group. In adult mouse cerebellum, F3 is predominantly expressed on a subset of axons, the parallel fibers, and at their synapses. In vitro studies established that it is a plurifunctional molecule that, depending on the cellular context and the ligand with which it interacts, either mediates repulsive interactions or promotes neurite outgrowth. In the present study, we report the isolation of two fractions of F3‐containing microdomains from adult cerebellum on the basis of their resistance to solubilization by Triton X‐100 at 4°C. Both fractions were composed of vesicles, ranging from 100 to 200 nm in diameter. Lipid composition analysis indicated that the lighter fraction was enriched in cerebrosides and sulfatides. F3 sensitivity to phosphatidylinositol phospholipase C differed between the two fractions, possibly reflecting structural differences in the lipid anchor of the F3 molecule. Both fractions were highly enriched in other glycosylphosphatidylinositol‐anchored proteins such as NCAM 120 and Thy‐1. It is interesting that these vesicles were devoid of the transmembrane forms (NCAM 180 and NCAM 140), which were recovered in Triton X‐100‐soluble fractions, but contained the L1 transmembrane adhesion molecule that is coexpressed with F3 on parallel fibers and the fyn tyrosine kinase. Immunoprecipitation experiments indicated that F3, but not NCAM 120 or Thy‐1, was physically associated in a complex with both L1 and fyn tyrosine kinase. This strongly suggests that the interaction between L1 and F3, already described to occur with isolated molecules, is present in neural tissue. More important is that our study provides information on the molecular machinery likely to be involved in F3 signaling.

Contragestion with late luteal administration of RU 486 (Mifepristone)

The efficacy and tolerance of RU 486 prescribed as a late luteal contragestive agent have been evaluated in 139 women at risk of pregnancy. They were given 400 or 600 mg of RU 486 once on the day before the expected menses. Among these women, 48 (34.5%) were pregnant (positive plasma beta-human chorionic gonadotropin, [beta-hCG]) at the time of RU 486 intake. Bleeding occurred in all but six women. An ongoing pregnancy after treatment was found in nine cases (failure rate, 9/48, 18.8%), which was subsequently terminated by surgical procedure in all cases. There was no disturbance in the menstrual cycle, and the tolerance was very satisfactory. In conclusion, this method is acceptable for women at risk of pregnancy in whom other usual postcoital contraceptive methods cannot be prescribed.

New Target Genes for NOV/CCN3 in Chondrocytes: TGF-β2 and Type X Collagen†

We studied the involvement of NOV/CCN3, whose function is poorly understood, in chondrocyte differentiation. NOV was found to upregulate TGF‐β2 and type X collagen and to act as a downstream effector of TGF‐β1 in ATDC5 and primary chondrocytes. Thus, NOV is a positive modulator of chondrogenesis.

A monoclonal antibody against Meningococcus group B polysaccharides used to immunocapture and quantify polysialylated NCAM in tissues and biological fluids

Polysialylated isoforms of neural cell adhesion molecule (PSA-NCAM) are transiently expressed in many tissues during development and in discrete areas of the adult central nervous system. In pathological situations, they are expressed by poorly differentiated tumor cells of neuroectodermal origin and by regenerating muscle. An ELISA is introduced here to estimate the relative concentrations of PSA-NCAM expressed by tissues or released into biological fluids. In this double-sandwich assay, an anti-PSA antibody (anti-MenB) was adsorbed onto plastic plates and permitted the immunocapture of PSA-bearing molecules. It is demonstrated that these molecules are major NCAM. The second antibody was directed against an amino acid sequence shared by NCAM isoforms in several species. The standard curves were established using Nonidet P40 extracts of human or mouse embryonic brain known to be rich in PSA-NCAM. The sensitivity of the assay allows for quantitation of PSA-NCAM in muscle during regeneration and in small samples of cerebrospinal fluid from patients with medulloblastoma metastasis.

NOV/CCN3 Induces Adhesion of Muscle Skeletal Cells and Cooperates with FGF2 and IGF-1 to Promote Proliferation and Survival

During mammalian development, expression of the Nephroblastoma overexpressed gene (NOV/CCN3) is tightly regulated in skeletal muscles. Ex vivo, ectopic expression of NOV blocks myogenic differentiation. NOV also supports endothelial cell adhesion and angiogenesis through interactions with integrins. Integrins play fundamental roles during myogenesis. In this study, we show that NOV mediates adhesion and spreading of myoblasts. Myoblasts adhesion to NOV does not require proteoglycans and is dependent on integrin β1, whereas spreading involves another RGD-sensitive integrin. The C-Terminal part of NOV as well as full-length is able to support adhesion of myoblasts; in addition, both increase focal-adhesion kinase (FAK) phosphorylation. Furthermore, NOV is an adhesive substrate that, combined with FGF2 or IGF-1, promotes cell specific proliferation and survival, respectively, in a better way than fibronectin. Taken together, these results identify NOV as an adhesion substrate for myoblasts which, in concert with growth factors, could play a role in the physiology of muscle cells.

Changes in ganglioside metabolism during in vitro differentiation of quail embryo myoblasts

The metabolism of gangliosides was studied during the in vitro differentiation of both normal quail myoblasts and myoblasts which have been transformed by a temperature-sensitive mutant of Rous sarcoma virus (RSV). These transformed cells can be maintained undifferentiated if incubated at 35 degrees C, but they will differentiate when shifted to 41 degrees C. (D. Montarras and M. Y. Fiszman (1983) J. Biol. Chem. 258, 3882-3888). The analysis of [14C]Glucosamine-labeled gangliosides by two-dimensional thin-layer chromatography reveals variations in the metabolism of the gangliosides during the process of differentiation. During the formation of myotubes, it was observed that the accumulation of GD1a is reduced, while the accumulation of GD3 is increased. Therefore, this results in the variation of the ratio GD3/GD1a which increases from 1.8 to 25 in the case of clones of transformed myoblasts, and from 0.5 to 1.7 in the case of uninfected myoblasts. These variations which have been observed seem to be specific of the myogenic differentiation since they cannot be reproduced when differentiation is inhibited by BUdR treatment or when fibroblasts reach confluency and are blocked in the G1 phase of cell cycle. Furthermore, the transformed myoblasts in vitro are shown to be a good model system since their gangliosides composition is very similar to that of muscle cells in vivo.

Stimulation of phosphatidylethanolamine synthesis during the last stages of the G1 phase in concanavalin A-activated human peripheral lymphocytes

Phospholipid synthesis was investigated in concanavalin A-activated human peripheral lymphocytes up until 72 h following cell activation, i.e., during the G1 and S phases of the cell cycle. Using [32P]phosphate pulse experiments (5 h), striking differences were observed between phosphatidylethanolamine (PE) and phosphatidylcholine (PC) synthesis. Both the incorporation of [32P]phosphate into PE and the PE/PC incorporation ratio were greatly enhanced, 16-fold and 8-fold, respectively, after 48 h of incubation with the mitogen. This increase in PE synthesis was still observed when cell entry into the S phase was inhibited by an excess of concanavalin A; thereby it must be related to the late stages of the G1 phase. The stimulation of the incorporation into PE was the same for both [14C]ethanolamine and [32P]phosphate, therefore suggesting the involvement of the phosphoethanolamine synthesis pathway. Kinetics of continuous incorporation of [32P]phosphate into PE and PC indicated that the PE/PC net synthesis ratio was enhanced in activated cells, which corresponds to PE enrichment in lymphocyte membranes. The stimulation of PE synthesis in late G1 may be of importance for cell progression through the cell cycle by changing the membrane physical properties. Furthermore, it may serve as a test for checking lymphocyte reactivity to mitogens.

Phosphate dilution lowers net phosphatidyl choline synthesis in lymphocytes.

The rate of net phosphatidyl choline (PC) synthesis in lymphocytes was evaluated, under appropriate conditions, in terms of [32P]phosphate incorporation. Phosphate-diluted and normal media were compared, with the cells being stimulated by concanavalin A or not. In either case, incubation in phosphate-diluted medium lowered net PC synthesis. In concanavalin A-stimulated cells, phosphate dilution also abolished the stimulation effect on net PC synthesis in G1. Nevertheless, these changes did not inhibit blastogenic transformation of cells.