Anne-Marie Vanbellinghen

Evidence for a clathrin-mediated recycling of albumin in human term placenta.

Abstract During human pregnancy, the trophoblast layer is in direct contact with maternal albumin. In contrast to immunoglobulins, albumin does not cross the placental barrier. However, albumin affects the trophoblast placental lactogen and chorionic gonadotroph secretion. The present study investigated the interaction between albumin and syncytiotrophoblast using human term placental explants. Bovine serum albumin, labeled with either 125I or fluorescein isothio-cyanate, was taken up rapidly by placental explants. This process was temperature-sensitive. The internalized labeled BSA quickly outflowed from the tissue at the maternal side, largely without any major modification in molecular weight. Colchicine (1 mM), which disrupts the microtubule network, or cytochalasin B (40 μM), which disassembles filamentous actin, did not interfere with the placental transmembrane movements of labeled BSA. Megalin, clathrin, and caveolin 1 are three membrane proteins associated with albumin endocytosis in other tissues, but only megalin and clathrin were detected in the syncytiotrophoblast layer by immunohistochemistry. The uptake of labeled BSA into placental explants was not modified by 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid (1 mM) or 5-nitro-2-(3-phenylpropylamino)benzoic acid (100 μM), two pharmacological tools known to disturb megalin-mediated albumin endocytosis. By contrast, methyl-β-cyclodextrin (10 mM) and chlorpromazine (1.4 mM), both of which disrupt the clathrin-mediated endocytotic system, significantly reduced the uptake of labeled BSA. These data suggest, to our knowledge for the first time, that maternal albumin is actively internalized into the human trophoblast according to an apical recycling pathway. This temperature-sensitive process does not depend on an intact cytoskeleton, but it is associated with a clathrin-mediated endocytotic system.

Epitope mapping on intact, heated and reduced molecular variants of human chorionic gonadotrophin

Monoclonal antibodies (MAbs) raised against purified human chorionic gonadotrophin (hCG) (n = 30) and synthetic peptides derived from hCG (n = 3) were able to recognize by Western blotting several hCG dimers (57-47 and 42 kDa), free beta-subunits (35-32, 26 and 16 kDa) and free alpha-subunit (21 kDa) which coexist in commercially available hCG preparations. According to differences in the immunoreactivity of hCG-related molecular forms observed under native or denaturing conditions such as boiling or reducing hCG samples before or after gel electrophoresis, nine classes of MAbs able to recognize different immunoreactive domains were determined. Three domains corresponded to continuous epitopes recognized by MAbs raised against hCG-related peptides. The six remaining domains, recognized by the other MAbs, contained discontinuous epitopes from which three were surface-oriented and three disguised in the holo-hormone. This solid-phase approach, combining native and denaturing conditions, represents a simple and powerful tool to screen the specificity of MAbs from varying sources and to investigate molecular variants of proteic hormone.

Ineffectiveness of chloroquine antenatal prophylaxis in East of Democratic Republic of Congo (RDC).

came from the Aids clinic that the hospital runs. It is therefore suggested that in countries where the Aids scourge is rampant oesophageal candidiasis should be kept in mind. The prevalence of normal endoscopies was rather high. This is expected since there are some UGI diseases, which cannot be conclusively diagnosed by using endoscopy only. These include motility disorders as well as nonspecific dyspepsia, which are associated with structures originating from fore gut analogue. Besides, there are a number of pyschologic diseases, which may present as dyspepsia. These findings are similar to those of Missalek et al. ID. Most of our patients were young adults with a mean age of 35.6 years and in other series young patients were found to have high prevalence of normal endoscopy II . What this study shows is that clinicians do not seem to be aware of the prevalence of these diseases in this area.

In-vivo and in-vitro assessment of the influence of ritodrine and oxytocin on the placental secretion of human chorionic gonadotrophin and placental lactogen

The purpose of this study was to evaluate, in vivo and in vitro, the influence of ritodrine and oxytocin on the placental release of human chorionic gonadotrophin (HCG) and placental lactogen (HPL). The in-vivo study was performed on maternal sera collected before and 1 h after the onset of either ritodrine treatment (50 micrograms i.v./min; administered to 15 women at risk of premature labour) or oxytocin infusion (2 mU i.v./min; administered to 21 women for acceleration of slow labour). The in-vitro study was performed on human term placental explants incubated in the presence of 4-400 ng ritodrine/ml or 15-1500 microU oxytocin/ml. HCG and HPL were measured by radioimmunoassay on maternal sera and incubation media. Maternal circulating concentrations of HCG and HPL remained unaffected after 1 h of ritodrine or oxytocin treatment. The in-vitro release of HCG and HPL by placental explants was not modified when ritodrine or oxytocin was added to the incubation media. The lack of influence of ritodrine and oxytocin on the placental secretion of HCG and HPL suggests that beta 2-adrenergic and oxytocin receptors are not involved in the releasing process.