Biomedical subjects
Publications and source records attributed to A Vokaer.
Sickle cell anemia is a severe disorder that rarely spares affected adults. We describe here a 32-year-old pregnant woman who presented her first lifetime symptoms of her disease during induction of labor at term. We therefore discuss the possible causes that may have triggered this inaugural crisis.
OBJECTIVE: To assess the accuracy of a single cervical fetal fibronectin test to predict spontaneous preterm delivery in an unselected antenatal population. DESIGN: A prospective blind cohort study. SETTING: Antenatal clinic of a teaching hospital in a Brussels semiurban area. PARTICIPANTS: An unselected group of 170 women followed at the antenatal clinic. METHODS: A single cervical sample was obtained between 24 and 33 completed weeks of pregnancy. The fibronectin test was compared with clinical evaluation and their predictive properties were assessed. RESULTS: Fifteen women were excluded from the analysis because of elective preterm delivery for medical indications or loss to follow up. Of the 155 remaining women, nine (7%) had a spontaneous preterm delivery. For a single fetal fibronectin test, the sensitivity was 26.7%, the specificity 95.7%, and the positive and negative predictive values 40.0% and 92.4%, respectively. The likelihood ratio of a positive was similar to that of clinical predictors of preterm birth (LR = 6.2; 95% CI 2.0-19.6). Sensitivities were low for both clinical criteria and the fetal fibronectin test. CONCLUSIONS: Because of low sensitivity in a low risk population, screening for preterm delivery should not be based on the result of a single fetal fibronectin test alone. However, due to its high specificity the test might be useful in avoiding unnecessary medical intervention.
We realised this study in order to determine the frequency of abnormal haemoglobins and to appreciate the need for a neonatal screening for haemoglobinopathies in Brussels. Over a two year-period, 9575 cord blood samples were systematically screened. The study disclosed following results : 40% of newborns were from regions at risk for haemoglobinopathies and abnormal haemoglobins were present in 2.5% of the neonates tested. This frequency is similar to those reported elsewhere in North Europe. The most frequent abnormal haemoglobins were the Hb S, Bart's, C, D and E. Three cases of severe forms of sickle cell anaemia were identified. The frequency of abnormal haemoglobins and Hb S traits combined to the high rate of mixed marriages (16%) justifies the need for a universal screening for haemoglobinopathies in Brussels.
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We report two infants with congenital absence of the anterior pituitary gland, documented by magnetic resonance imaging (MRI) or autopsy. In cord plasma obtained at birth from both infants, prolactin (PRL), pituitary growth hormone (hGH), placental growth hormone (hPGH) and thyrotropin (TSH) were undetectable; cortisol was low; thyroxine (T4) was 31 nmol/l in one infant and 85 nmol/l in the other infant who had been treated prenatally with intra-amniotic L-T4 administration. In maternal plasma at birth, PRL, hPGH and T4 were normal and hGH was undetectable. These observations suggest that plasma hGH and PRL in the fetus are exclusively of fetal pituitary origin, hPGH is secreted into the maternal circulation and is not transferred to the fetus and fetal growth can be normal in the absence of hGH, hPGH and PRL in fetal plasma.
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Preterm delivery occurs in 5-10% of live births. Preterm labour is the leading cause of perinatal mortality and morbidity. It accounts for one third of perinatal deaths. Clinicians stay faced to the use of tocolytic therapy carrying the risks of side-effects for the fetus and the mother. The regulation of uterine contractility through myosin phospho-dephosphorylation is controlled by second messenger system (Calcium, cAMP). Furthermore, some hormones seem to control the development and the regression of gap junctions which promote synchronous muscle activity by allowing electrical and mechanical coupling of the cells within different regions of the uterus. Understanding of these cellular regulatory processes is the rationale to the choice of tocolytic drugs actually available. It sounds to be a further step to innovative approaches to tocolytic therapy without or with less significant side effects.
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Ten Belgian maternity hospitals have collaborated in an international clinical multicenter trial: Multicenter Fetal Movement Trial. Nine maternity hospitals were already managing a computerized data bank before their participation in the trial. In seven of these centers the local team was able to write a program for direct transmission of data, using standard sequential ASCII files. This procedure presents many advantages: there is a gain in time and money, since it is no longer necessary to fill out data collecting forms, or coding at a central level. Transcription errors are avoided, adhesion to strict and standard definitions is guaranteed, the micro-systems are performing in a suitable fashion in each center, modifications of parameters (and corrections) are done very quickly and, automatically carried out, on the basis of clinical data as well as "research" data, transmission by telecommunication is immediately and easily feasible.
The effects of androstenedione (AD) on cell proliferation and kinetics have been measured in MXT mouse and MCF-7 human mammary cancer cell lines using SAMBA 200 cell image analysis of Feulgen-stained nuclei. At a concentration of 0.01 microM AD inhibited the proliferation of both cell lines whereas a higher dose (1 microM) was inhibitory on MCF-7 cell proliferation but stimulatory in MXT cells. It is unlikely that these effects are due to aromization of AD into oestrogen since (a) both cell lines were devoid of aromatase and (b) both cell lines were similarly affected by oestradiol (E2), being stimulated at low concentrations and inhibited at high doses. Furthermore, inhibition by AD seems to occur, at least in part, by blockade of the cell cycle whereas that by E2 appears to be cell cycle independent.
A case of thymoma associated with pregnancy is reported. This association is extremely rare (8 described cases) and the clinical outcome is most frequently unfavorable for the mother. The diagnosis was given by a standard chest X-ray performed routinely post-partum. Sixteen months after total surgical extirpation of the tumor and adjunctive radiotherapy the patient is still in complete remission. The presented case is discussed with reference to a review of literature.
alpha 2-Adrenergic receptors were identified in calf brain, human platelet and human uterus membranes by [3H]-rauwolscine binding. The reagents phenylglyoxal (selective for guanidino groups), p- hydroxy mercuribenzoate and N-ethylmaleimide (selective for sulfhydryl groups) caused a time- and dose- dependent decrease in the number of receptor sites. alpha 2-Adrenergic agonists and antagonists mediated efficient protection of the receptors against these reagents. These data suggest that essential arginine and cysteine residues are present at or near the alpha 2-adrenergic binding site.
Both alpha- and beta-adrenergic receptors have been identified in the human myometrium by radioligand binding. Both adrenergic receptor subclasses have been shown to mediate the contractile response of the uterus upon catecholamine stimulation: alpha-adrenergic receptors cause uterine contraction while beta-adrenergic receptors induce relaxation. We have identified alpha 1- and alpha 2-adrenergic receptors in myometrial membranes using the newly developed radiolabelled specific antagonists [3H]-prazosin and [3H]-rauwolscine. This enabled us to characterize both receptor subclasses individually. Beta adrenergic receptors were identified using the radiolabelled antagonist (-)-[3H]-dihydroalprenolol. Binding of radioligands to the myometrial membrane receptors was rapid, readily reversible, of high affinity and stereoselective. The total number of alpha 1-, alpha 2- and beta-receptors was determined by Scatchard analysis of radioligand saturation binding and the beta/beta 2-receptor ratio was determined by computer analysis of the beta 2-selective antagonist ICI 118 551) (-)-[3H]-dihydroalprenolol competition binding curves. This enabled us to study the regulation of both alpha- and beta-receptor subclasses under various physiological and pharmacological conditions in the human, i.e., during different phases of the menstrual cycle, in postmenopausal women and during depo-progestin (Medroxyprogesterone acetate) therapy. Only the alpha 2- and beta 1-adrenergic receptor concentrations were found to be subjected to gonadal steroid regulation. The number of alpha 2- and beta 1-adrenergic receptors increased concomitantly with circulating plasma oestradiol levels. This effect was counteracted by progesterone. The number of alpha 1- and beta 2-adrenergic receptors was unaffected by the gonadal steroid environment. These results are an example of the heteroregulation of membrane receptors by oestrogens and progesterone and cast new light on the regulatory mechanisms involved in uterine contractility in the human.
The authors describe a new case of multiple cutaneous leiomyomata: a female patient aged 33 presents lesions in hundreds causing severe pain. The subjective symptoms are highly improved by the calcium antagonist nifedipine.
Human myometrium contains alpha 3-adrenergic receptors which can be identified by binding of the alpha 2-adrenergic antagonist [3H]rauwolscine. Scatchard analysis of saturation binding data on myometrial membranes revealed that [3H]rauwolscine bound to a single class of noncooperative sites (262 +/- 89 fmol/mg of membrane protein) with high affinity (i.e., with an equilibrium dissociation constant of 5.3 +/- 2.2 nM). The alpha 2-adrenergic nature of these sites was derived from the order of potencies and stereospecificity of alpha-adrenergic agonists and antagonists to compete with [3H]rauwolscine binding.
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Adrenergic receptors have been shown to be involved in uterine contractility. alpha-Adrenergic receptors cause uterine contraction, whereas beta-adrenergic receptors induce relaxation. In animals, myometrial alpha-adrenergic receptors are regulated by gonadal steroids. We have identified alpha 1- and alpha 2-adrenergic receptors in myometrial membranes using the newly developed radiolabeled specific antagonists [3H]prazosin and [3H]rauwolscine. This allowed characterization of both receptor subclasses individually and study of them in various physiological and pharmacological conditions in the human, i.e. during different phases of the menstrual cycle, in postmenopausal women, term pregnancy, and during depo-progestin (medroxyprogesterone acetate) therapy. The affinity and number of alpha 1-adrenergic receptors were unchanged in all conditions, whereas the number of alpha 2-adrenergic receptors increased concomitantly with circulating plasma estradiol levels. However, this latter effect was counteracted by progesterone. These results are an example of the heteroregulation of membrane receptors by estrogens and progesterone and throw new light on the regulatory mechanisms involved in uterine contractility in the human.