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J Guibourdenche

Publications and source records attributed to J Guibourdenche.

50 records · Page 3Linked to original sources
PubMed1997

Human placental growth hormone.

Placental growth hormone is the product of the GH-V gene specifically expressed in the syncytiotrophoblast layer of the human placenta. Placental growth hormone differs from pituitary growth hormone by 13 amino acids. It has high somatogenic and low lactogenic activities. Assays by specific monoclonal antibodies reveal that in the maternal circulation from 15 to 20 weeks up to term placental growth hormone gradually replaces pituitary growth hormone, which becomes undetectable. It is secreted by the placenta in a nonpulsatile manner. This continuous secretion appears to have important implications for physiologic adjustment to gestation and especially in the control of maternal insulin-like growth factor-I levels. Placental growth hormone secretion is inhibited by glucose in vitro and in vivo and is significantly decreased in the maternal circulation in pregnancies with intrauterine growth restriction. Placental growth hormone does not appear to have a direct effect on fetal growth because this hormone is not detectable in the fetal circulation. However, the physiologic role might also include a direct influence on placental development through an autocrine or paracrine mechanism, as suggested by the presence of specific growth hormone receptors in this tissue.

Growth Hormone↗
PubMed1997

Fetal fibronectin in the cervical secretion predicts accurately the onset of labor at term.

OBJECTIVE: The objective of our study was to check if presence of fetal fibronectin in the cervical secretion of full term patient predicts accurately the onset of labour at term. STUDY DESIGN: 78 women in the term period were included in the study, serial samples for fetal fibronectin were assessed, each patient underwent spontaneous labour, delay between last sample and delivery were analysed. RESULTS: Patient with positive fetal fibronectin delivered within 3 +/- 1.9 days where as patient with negative fetal fibronectin delivered within 5.7 +/- 3.9 days (P = 0.01). CONCLUSION: Presence of fetal fibronectin in cervical secretions seems to be a powerful tool to predict in a short delay the onset of labour at term, it should be used in conjunction with clinical and fetal assessment data.

Adult↗
PubMed1997

Bone mineral density and metabolism in children with congenital hypothyroidism after prolonged L-thyroxine therapy.

The effect of long-term L-thyroxine (LT4) replacement therapy on bone mineral density and on biochemical markers of bone turnover were studied in children with congenital hypothyroidism (CH). Forty-four children and adolescents (mean age 8.5 +/- 3.5 years) with primary CH who began LT4 replacement therapy within the first month of life were studied. Bone mineral density (BMD) of the lumbar vertebrae and the upper femoral bone was measured by dual energy X-ray absorptiometry. Serum osteocalcin (OC) and bone alkaline phosphatase were measured as markers of bone formation and urinary deoxypyridinoline was taken as a marker of bone resorption. Bone mineral densities of CH children were not different from those in age-matched controls. The biochemical markers of bone turnover were normal except for the serum OC levels which were found to be higher than in controls and positively correlated with the free thyroid hormone levels (for FT4 r = 0.42, p = 0.02). Eight CH children demonstrated low BMD values (below -1 SDS) at -2 +/- 0.7 SDS for the lumbar spine and -1.6 +/- 0.5 SDS for the femoral site. These eight children showed lower mean weight (p < 0.05) and their dietary calcium intake tended to be less (p <0.06) than that seen in the normal BMD group. In conclusion, our results show that LT4 replacement therapy for 8 years is not detrimental to the skeletal mineralization of CH children. As in a healthy population, weight and current intake of calcium seem to be major determinants of bone density. Dietary recommendations, especially when calcium intake is below the recommended dietary allowance, may have to be reconsidered.

Absorptiometry, Photon↗
PubMed1997

Real time validation of paediatric biochemical reports using the Valab-Biochem system.

Validation of biochemical reports must be fast and clinically accurate to be of assistance to clinicians. Considerable skill is required to analyse the consistency of different data in the report and to consider influences on the data. When performed throughout the day, such analysis is time-consuming and uncertain. We therefore decided to use a computer-assisted validation system, Valab-Biochem. Its decisions result from a decision tree based primarily on the intrinsic consistency of the data, validation ranges and patients' sex, age and hospital ward. Three hundred randomly chosen reports were simultaneously submitted to Valab-Biochem and to five biologists in order to analyse the computer's findings. The sensitivity of Valab-Biochem was 80% compared to biologists' consensus decision, which was taken as the gold standard. The specificity was 78%. This system provided autonomous assessment of the reports and could be used as an initial screen to assist biologists and focus attention on potentially inconsistent reports.

Artificial Intelligence↗
PubMed1996

Hypoxia impairs cell fusion and differentiation process in human cytotrophoblast, in vitro.

During human pregnancy, the trophoblast develops from differentiation of cytotrophoblast cells into an endocrine active syncytiotrophoblast. In culture, isolated mononuclear cytotrophoblasts aggregate and then fuse to form a syncytium, reproducing the in vivo process. In this study, we examined the effect of low oxygen tension (approximately 9%, hypoxia) compared to standard conditions (approximately 19% oxygen, normoxia) on these cellular events. Under hypoxia, syncytial formation was less frequently observed, cell staining and electron microscopy revealed that cytotrophoblasts remain aggregated, with a positive proliferative cell nuclear antigen (PCNA) immunostaining. Desmoplakin and E-cadherin, both known to disappear with cytotrophoblast fusion, showed persistent expression in hypoxic cells after 3 days of culture. In contrast, the expression of actin and ezrin, two cytoskeletal proteins, was unchanged. hCG secretion and hPL expression were both decreased in hypoxic cells, reflecting a reduced syncytial formation. Thus, on day 3, the mean values for hCG secretion were 1,100 +/- 155 and 289 +/- 26 mlU/mL in normoxic and hypoxic conditions, respectively. The reduced cell fusion process as well as hCG secretion and hPL expression under hypoxia were reversed by reoxygenation of the cells. We conclude that under hypoxia, the formation of functional syncytiotrophoblast is impaired due to a defect in the cytotrophoblast fusion process. This may explain the observation of a higher number of cytotrophoblast cells and a reduced syncytial layer in placentas of some pathological pregnancies.

Actins↗
PubMed1996

Vitamin A and retinoic acid stimulate within minutes cAMP release and growth hormone secretion in human pituitary cells.

In order to gain a better understanding on the possible role of vitamin A (VA) and retinoic acid (RA) on human growth hormone (GH) secretion, we used the physiological model of pituitary cells perifusion. In perifused cells from pituitary somatotropic adenomas, RA induced within minutes a peak of GH secretion. This effect was dose dependent, maximal effect being observed with 100 nM. The GH release was associated with a discharge of cAMP delayed by 4 to 8 minutes relative to the GH surge. Similar results were obtained after VA stimulation. Our observations provide the first evidence of an action of VA and RA on cAMP production. They suggest a role of RA and VA in the regulation of human GH secretion via the cAMP dependent pathway.

Adult↗
PubMed1994

Differential secretion of alpha 1-acid glycoprotein occurs in the Golgi complex of isolated rat hepatocytes. Evidence of partial retention in the Golgi.

Using weakly basic amines, we investigated the step at which the secretion kinetics of concanavalin-A-retained and nonretained alpha 1-acid glycoprotein glycoforms diverge in isolated rat hepatocytes. Both chloroquine and primaquine, whose action on protein secretion is targeted to terminal domains of the Golgi apparatus, cancelled the kinetic difference without influencing carbohydrate chain sialylation. To test for a possible interaction of alpha 1-acid glycoprotein with Golgi membranes, we also permeabilized control and primaquine-treated hepatocytes, as well as purified Golgi preparations, with saponin. In each case, we found that alpha 1-acid glycoprotein was associated with Golgi membranes, the association being more marked in primaquine-treated cells than in control cells. Membrane-bound alpha 1-acid glycoprotein appeared to be preferentially retained on concanavalin A. Such retention could account for the divergent secretion kinetics of alpha 1-acid glycoprotein glycoforms.

Animals↗
PubMed1992

Differential rates of glycoprotein secretion by isolated rat hepatocytes studied in terms of concanavalin A binding.

Using a concanavalin-A-based method which respects cell function, we have shown that the kinetics of glycoprotein secretion appear to depend on the nature of the oligosaccharide moiety. In 37 degrees C pulse/chase experiments using freshly isolated normal rat hepatocytes, we found that except for transferrin, whose rate of secretion was independent of its concanavalin A reactivity, the secretion of the concanavalin-A-retained forms of alpha 1 acid glycoprotein, T-kininogen, alpha 1 protease inhibitor and alpha 1 inhibitor III was slower than that of the concanavalin-A-non-retained forms. When hepatocytes were incubated at 20 degrees C, secretion was blocked with the accumulation of mainly endoglycosidase-H-sensitive forms. The secretion kinetics of the concanavalin-A-differentiated forms were still different when the temperature was shifted back to 37 degrees C. The divergence between the secretion rates of the concanavalin-A-differentiated forms would appear to be due to a late event in intracellular protein trafficking, which may depend on the sugar content and/or the number of carbohydrate chains of the glycoproteins.

Acute-Phase Proteins↗
PubMedDate not supplied

[Placental hormones and fetal growth].

Fetal growth is controlled by the placenta which mediates fetal nutritional supplies. During pregnancy, the placenta secretes a specific placental growth hormone which replaces the pituitary growth hormone in the maternal circulation. Placental growth hormone is one example of the materno-placental cooperation which is impaired in cases of intra-uterine growth retardation.

Embryonic and Fetal Development↗
PubMedDate not supplied

Effect of amnioinfusion on the outcome of prenatally diagnosed gastroschisis.

OBJECTIVE: Following recent data showing that an inflammatory response exists in the amniotic fluid of gastroschisis-affected fetuses, we hypothesized that amniotic fluid exchange or amnioinfusion would improve the prognosis of prenatally diagnosed gastroschisis. METHODS: We compared the outcome of prenatally amnioinfused fetuses with gastroschisis to non-amnioinfused fetuses with gastroschisis. 10 patients undergoing this procedure were matched with 10 patients of our previous study. Comparisons were done on data including surgical procedure, follow-up in the NICU and the gastro-pediatric unit. RESULTS: Our results show that gastroschisis-affected fetuses undergoing amnioinfusion had a lower duration of curarization after surgery (2.2 +/- 1.9 vs. 6.8 +/- 6.9 days, p = 0.019), a shorter delay before full oral feeding (49.7 +/- 21.5 vs. 72.3 +/- 56.6 days, NS), and a shorter overall length of hospitalization (59.5 +/- 19.7 vs. 88.5 +/- 73.6 days, NS). We confirmed our previous data showing that amniotic fluid displays a chronic inflammation profile. CONCLUSION: Our data suggest that amnioinfusion could improve the outcome of gastroschisis affected fetuses. The hypothesis by which this improvement could be due to a reduction of an inflammatory response remains to be proved.

Adult↗
PubMedDate not supplied

Influence of amnioinfusion in a model of in utero created gastroschisis in the pregnant ewe.

OBJECTIVE: Recent studies on the management of human fetal gastroschisis have produced two major findings: (1) there is an inflammatory response in the amniotic fluid of these fetuses, and (2) amniotic fluid exchange designed to disrupt the inflammatory loop seems to have a favorable impact on the immediate and late outcome of these early operated neonates. To test this hypothesis, we used serial amniotic fluid exchanges in a model of gastroschisis developed in the ewe. METHODS: Gastroschisis was created at midgestation in 21 lamb fetuses by an in utero technique. Saline was amnioinfused in some fetuses every 10 days to term. Fetuses were sacrificed on day 145 by cesarean section. Extra-abdominal bowels with fibrous peel were processed for histologic examination. Comparisons were done between fetuses without gastroschisis (controls), fetuses with gastroschisis and amnioinfusion, and fetuses with gastroschisis without amnioinfusion. RESULTS: Of 21 fetuses operated, 8 died in utero or were stillborn; 5 were not amnioinfused, and 8 underwent amnioinfusion. Thickness of bowel muscularis (micrometer) was 92.6 +/- 20.2 for controls, 126.2 +/- 21 for the amnioinfused fetuses, and 182.8 +/- 58.3 for the nonamnioinfused fetuses (p = 0.001). The same significant results were obtained for thickness of serous fibrosis (p = 0.02) and plasma cell infiltration (p = 0.015). CONCLUSIONS: We have created a model of gastroschisis suitable for experimentation in the fetal sheep. Our amnioinfusion data in this model indicate a clear improvement of the deleterious process. This finding correlates well with recent data on amnioinfusion as a therapeutic approach to human gastroschisis.

Amniotic Fluid↗
PubMedDate not supplied

Prognostic factors of prenatally diagnosed gastroschisis.

OBJECTIVE: To evaluate the prognosis of prenatally diagnosed gastroschisis. STUDY DESIGN: In a retrospective study, we analyzed the clinical and echographic data of gastroschisis. These data were correlated with fetal outcome including delivery, surgical procedure, follow-up in the neonatal intensive-case unit and in the gastropediatric unit. RESULT: Twenty cases were analyzed. The overall survival rate was 85%. Classical criteria were analyzed (maximal bowel dilatation, thickening of bowel wall). Fetuses with both severe perivisceritis and meconium-stained amniotic fluid were born earlier than fetuses with mild perivisceritis and normal amniotic fluid (p < 0.01). CONCLUSION: Our data suggest that an inflammatory response could follow bowel exposure to amniotic fluid. This response could lead to perivisceritis and premature birth. This hypothesis is currently under investigation.

Adolescent↗