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Biomedical subjects

M Teboul

Publications and source records attributed to M Teboul.

At least 19 recordsLinked to original sources
PubMed2004

[Management of labor and delivery in low risk nulliparous women: comparison between level 1 and level 3 maternities].

OBJECTIVES: To compare obstetrical practices between level 1 ( community hospital) and level 3 (university hospital) maternities in a low risk nulliparous population. MATERIALS AND METHODS: 1532 low risk nulliparas were included in a retrospective study conducted in the setting of two maternities in the Ile-de-France area. Cesarean delivery and forceps rates, management of labor, analgesia, maternal and neonatal outcomes were compared. RESULTS: Cesarean delivery rates were not significantly different (11.5% in level 3 vs 10.2% in level 1). Level 1 maternity performed induction of labor more often (14.7% vs 8.7%, p<0.01). Peridural analgesia rates were higher in the level 3 maternity (95.1% vs 75.5%. p<0.01) but general anesthesia was two-fold more frequent in level 1 maternity. Level 3 maternity performed more instrumental deliveries (27.5% vs 17.4%, p<0.01) and more episiotomies (72.7% vs 39.3%). But we noted more first and second degree perineal tears in the level 1 maternity (29.9% vs 17.4%, p<0.01). Neonatal hospitalizations were more frequently in level 3 maternity. CONCLUSION: Some "interventionist" practices, but not all, were less frequent amongst physicians managing mainly low-risk women than amongst physicians managing mainly high-risk women but without difference for the cesarean delivery rates. The main differences were observed for epidural, instrumental delivery, and episiotomy rates but perineal tears and induction of labor were more frequent in the level I maternity. These differences could be explained by obstetrical politics in the two maternities rather than the type of level.

Adult↗
PubMed2001

Adipose angiotensinogen is involved in adipose tissue growth and blood pressure regulation.

White adipose tissue and liver are important angiotensinogen (AGT) production sites. Until now, plasma AGT was considered to be a reflection of hepatic production. Because plasma AGT concentration has been reported to correlate with blood pressure, and to be associated with body mass index, we investigated whether adipose AGT is released locally and into the blood stream. For this purpose, we have generated transgenic mice either in which adipose AGT is overexpressed or in which AGT expression is restricted to adipose tissue. This was achieved by the use of the aP2 adipocyte-specific promoter driving the expression of rat agt cDNA in both wild-type and hypotensive AGT-deficient mice. Our results show that in both genotypes, targeted expression of AGT in adipose tissue increases fat mass. Mice whose AGT expression is restricted to adipose tissue have AGT circulating in the blood stream, are normotensive, and exhibit restored renal function compared with AGT-deficient mice. Moreover, mice that overexpress adipose AGT have increased levels of circulating AGT, compared with wild-type mice, and are hypertensive. These animal models demonstrate that AGT produced by adipose tissue plays a role in both local adipose tissue development and in the endocrine system, which supports a role of adipose AGT in hypertensive obese patients.

Adipocytes↗
PubMed2001

Angiotensinogen-deficient mice exhibit impairment of diet-induced weight gain with alteration in adipose tissue development and increased locomotor activity.

White adipose tissue is known to contain the components of the renin-angiotensin system, which gives rise to angiotensin II from angiotensinogen (AGT). Recent evidence obtained in vitro and ex vivo is in favor of angiotensin II acting as a trophic factor of adipose tissue development. To determine whether AGT plays a role in vivo in this process, comparative studies were performed in AGT-deficient (agt(-/-)) mice and control wild-type mice. The results showed that agt(-/-) mice gain less weight than wild-type mice in response to a chow or high fat diet. Adipose tissue mass from weaning to adulthood appeared altered rather specifically, as both the size and the weight of other organs were almost unchanged. Food intake was similar for both genotypes, suggesting a decreased metabolic efficiency in agt(-/-) mice. Consistent with this hypothesis, cellularity measurement indicated hypotrophy of adipocytes in agt(-/-) mice with a parallel decrease in the fatty acid synthase activity. Moreover, AGT-deficient mice exhibited a significantly increased locomotor activity, whereas metabolic rate and mRNA levels of uncoupling proteins remained similar in both genotypes. Thus, AGT appears to be involved in the regulation of fat mass through a combination of decreased lipogenesis and increased locomotor activity that may be centrally mediated.

Adipose Tissue↗
PubMed2000

Angiotensinogen, angiotensin II and adipose tissue development.

Adipose tissue is an important source of angiotensinogen (AGT). Recent evidence shows that a local renin-angiotensinogen system (RAS) is present in human adipose tissue and may act as a distinct system from plasma RAS. In obese patients, the involvement of angiotensin II (angII) as a consequence of increased plasma AGT secreted from adipose tissue has been proposed in the development of hypertension. Another role of AGT via angII in the development of adipose tissue is supported by the following: (i) in vitro, angII stimulates the production and release of prostacyclin from adipocytes, which in turn promotes the differentiation of precursor cells into adipocytes; (ii) ex vivo and in vivo, both angII and (carba)prostacyclin promote the formation of new fat cells; and (iii) AGT -/- mice exhibit a slowing down of adipose tissue development, as compared to wild-type mice. Altogether the data are consistent with an autocrine/paracrine mechanism implicating AGT, angII and prostacyclin in adipose tissue development.

Adipocytes↗
PubMed1996

Calcitriol down-modulates the 3,5,3' triiodothyronine (T3) receptors and affects, in a biphasic manner, the T3-dependent adipose differentiation of Ob 17 preadipocytes.

In previous reports, we showed that T3 is required for terminal differentiation of the murine Ob 17 preadipocytes, and that it partially down-modulates the abundance of its own nuclear receptor sites (T3R). We also reported that a profound depletion of the T3R was produced by all-trans-retinoic acid at concentrations that inhibit adipose differentiation. Here, we report that calcitriol (VD), which activates a nuclear receptor (VDR) closely related to the T3R and retinoid receptors, also markedly affects nuclear T3 binding and T3-induced differentiation of Ob 17 cells. Within a nearly physiological concentration range (0.1-2.5 nM), calcitriol profoundly down-modulated T3R abundance without altering the affinity for T3. The T3R depletion was a fast event, sustained under VD and reversed within 48 h of VD withdrawal. The order of efficient concentration ranges of VD and analogs suggests an involvement of the VDR. The T3R-depleting effect of VD was observed at every stage of adipose differentiation and was additive to the depleting effect of T3. Within the 0.1-2.5 nM VD concentration range, the c-erbA alpha and -alpha 1 messenger RNA levels (only c-erbA alpha gene products were detected in these cells) were poorly decreased; VD also did not alter a protein band specifically detected with specific anti-c-erbA alpha 1 antibodies in Western blots of nuclear extracts. VD accelerated the T3R disappearance rate; the results suggest that this would probably involve sequestration, rather than degradation, events. Interestingly, calcitriol added to the culture medium of Ob 17 preadipocytes markedly influenced the adipose differentiation, exerting a clear-cut stimulation at levels of 0.25 nM or less and profound inhibition at concentrations above 0.25 nM. Both effects were observed provided that VD was added within an early critical period of the differentiation process, as we previously reported for T3. The stimulations caused by low concentrations of VD and 1.5 nM T3 were additive. Increasing the VD concentration produced a progressive attenuation, then a suppression, of the stimulating effect of T3. Comparative analyses of VD-related changes in adipose differentiation and T3R abundance suggest that a correlation may exist between optimal differentiation and a partial depletion of the T3R, whereas a profound depletion of the T3R occurred at inhibitory concentrations of VD. The present results sustain the concept that T3R play a role in the differentiation of Ob 17 preadipocytes. Moreover, the results suggest that there may be a T3 receptor site concentration optimal for efficient differentiation. A regulation of this concentration involves ligands of other closely related receptors and, thus, probably the interplays that exist between these receptors.

Adipocytes↗
PubMed1995

OR-1, a member of the nuclear receptor superfamily that interacts with the 9-cis-retinoic acid receptor.

We have cloned a member of the nuclear receptor superfamily. The cDNA was isolated from a rat liver library and encodes a protein of 446 aa with a predicted mass of 50 kDa. This clone (OR-1) shows no striking homology to any known member of the steroid/thyroid hormone receptor superfamily. The most related receptor is the ecdysone receptor and the highest homologies represent < 10% in the amino-terminal domain, between 15-37% in the carboxyl-terminal domain and 50-62% in the DNA binding domain. The expression of OR-1 appears to be widespread in both fetal and adult rat tissues. Potential DNA response elements composed of a direct repeat of the hexameric motif AGGTCA spaced by 0-6 nt were tested in gel shift experiments. OR-1 was shown to interact with the 9-cis-retinoic acid receptor (retinoid X receptor, RXR) and the OR-1/RXR complex to bind to a direct repeat spaced by 4 nt (DR4). In transfection experiments, OR-1 appears to activate RXR-mediated function through the DR4. Therefore OR-1 might modulate 9-cis-retinoic acid signaling by interacting with RXR.

Amino Acid Sequence↗
PubMed1995

Nuclear factors specifically favor thyroid hormone binding to c-ErbA alpha 1 protein (thyroid hormone receptor alpha) over-expressed in E. coli.

A recombinant rat thyroid hormone receptor alpha (TR alpha or c-ErbA alpha 1) was produced in E. coli as a non-mutated, nonfusioned protein and obtained as an efficient DNA and T3 binding protein that could be easily handled in a buffer-soluble state (rec-TR alpha). It was found that nuclear extracts (NE) added to rec-TR alpha markedly amplified not only DNA binding, which has been well documented, but also T3 binding (increased binding site concentration), which has not yet been reported. This T3 binding amplifying effect on rec-TR alpha occurs at low NE protein concentrations that produce no or minimal endogenous TR with respect to rec-TR, while similar concentrations of other proteins (e.g. ovalbumin or cytosol) only moderately enhanced T3 binding. The T3 binding amplifying nuclear factors, which are partly heat-labile, appeared as necessary auxiliaries in the analyses of partially purified rec-TR alpha. A protective effect of NE against a loss of affinity for T3 under the action of antibodies directed to certain sequences in the TR alpha D domain suggests that nuclear factors help rec-TR alpha to acquire and/or stabilize a conformation that allows the high affinity T3 binding. The nature of this nuclear amplifying factor is still unknown: RXR alpha which, produced in vitro, could amplify binding of the rec-TR alpha to a DNA thyroid response element, was unable to display such a rescue of high affinity binding sites.

Animals↗
PubMed1995

Fatty acid activation of peroxisome proliferator-activated receptor (PPAR).

Peroxisome proliferators such as clofibric acid, nafenopin, and WY-14,643 have been shown to activate peroxisome proliferator-activated receptor (PPAR), a member of the steroid nuclear receptor superfamily. We have cloned the cDNA from rat that is homologous to that from mouse, which encodes a 97% similar protein. To search for physiologically occurring activators, we established a transcriptional transactivation assay by stably expressing in CHO cells a chimera of rat PPAR and the human glucocorticoid receptor that activates expression of the placental alkaline phosphatase reporter gene under the control of the mouse mammary tumor virus promoter. 150 microM concentrations of arachidonic or linoleic acid but not of dehydroepiandrosterone, cholesterol, or 25-hydroxy-cholesterol, activated the receptor chimera. In addition, saturated fatty acids induced the reporter gene. Shortening the chain length to n = 6 or introduction of an omega-terminal carboxylic group abolished the activation potential of the fatty acid. To test whether a common PPAR binding metabolite might be formed from free fatty acids we tested the effects of differentially beta-oxidizable fatty acids and inhibitors of fatty acid metabolism. The peroxisomal proliferation-inducing, non-beta-oxidizable, tetradecylthioacetic acid activated PPAR to the same extent as the strong peroxisomal proliferator WY-14,643, whereas the homologous beta-oxidizable tetradecylthiopropionic acid was only as potent as a non-substituted fatty acid. Cyclooxygenase inhibitors, radical scavengers or cytochrome P450 inhibitors did not affect activation of PPAR. In conclusion, beta-oxidation is apparently not required for the formation of the PPAR-activating molecule and this moiety might be a fatty acid, its ester with CoA, or a further derivative of the activated fatty acid prior to beta-oxidation of the acyl-CoA ester.

Animals↗
PubMed1995

Antibodies against restricted sequences in human c-ErbA hinge domain recognize differentially natural mammalian alpha- or beta-type triiodothyronine receptors and interfere differently with hormone binding.

In our first report, rabbit antibodies directed to recombinant polypeptides of human alpha-type c-ErbA sequences recognized natural triiodothyronine (T3) receptors (TR) in adipocytes (mouse Ob 17 cell line) but not in liver (mouse, rat). Moreover, some of them, directed to the sequence 150-228, markedly interfered with hormone binding to adipocyte T3 receptors. We now raised antibodies against shorter synthetic peptides within this alpha-type 150-228 c-ErbA sequence, which encompasses part of the hinge (D) domain and N-terminus of the E domain (alpha-150-166 and alpha 172-191) and against a beta-type c-ErbA sequence (beta 204-220 aligned on alpha 150-166, and differing by eight amino acids). Our present antibodies, which bear the expected c-ErbA alpha- or beta-type specificity, immunoprecipitated the TR in nuclear extracts, with a different pattern between tissues: exclusive precipitation by anti-c-ErbA alpha antibodies in Ob 17 adipocytes; large but non-exclusive precipitation by anti-cErbA beta antibodies in rat or mouse liver, which also expresses some alpha-type TR. This pattern of discriminative immunoprecipitation, also obtained in parallel analysis using our previously described antibodies to other c-ErbA alpha or beta sequences (anti-alpha 144-162, anti-alpha 1 403-410 and anti-beta 62-82), roughly verifies results of c-erbA mRNA expression in these tissues. Slight differences appeared in the extent of alpha-type TR recognition by antibodies directed to alpha 172-191, whether TR were liganded or not to T3 before antibody addition. This evokes a different conformation of this region after hormone binding. Most interestingly, these anti-alpha 172-191 antibodies lowered the Ka for T3 and extensively dissociated the adipocyte T3-TR complexes; they interfered poorly with the binding of T3 in liver nuclear extracts. This strongly supports the concept that internal sequences in c-ErbA alpha, more precisely in a restricted C-terminal part of the D domain, are necessary for efficient T3 binding, which also need the C-terminal part of domain E.

Amino Acid Sequence↗
PubMed1994

Topical metronidazole as an adjunct to subgingival debridement in the treatment of chronic periodontitis.

The purpose of this study was to evaluate the clinical effects of a single application of a 5% metronidazole collagen device in periodontal pockets deeper than 5 mm, in association with debridement and without reinforcement of home care and hygiene as practiced by the patient at any time. Pocket depth, attachment level, bleeding on probing, gingival index and plaque index were assessed at baseline, and on days 15, 30 and 90. Analysis of data from 28 patients indicated that both debridement and metronidazole therapy decreased pocket depth, bleeding on probing and gingival index, but results were significantly better with metronidazole. These results indicate that topical metronidazole provides an effective adjunctive treatment of advanced periodontitis.

Adult↗
PubMed1993

Increase of adipose differentiation by hypolipidemic fibrate drugs in Ob 17 preadipocytes: requirement for thyroid hormones.

The action of hypolipidemic fibrate drugs (HFD) (clofibrate, bezafibrate, fenofibrate) was studied in relation to thyroid hormone (TH) action in the TH-sensitive Ob 17 preadipocyte cells which require an early presence of TH for terminal differentiation. HFD markedly amplified the adipose differentiation and the development of several lipogenic enzymes, thus accelerating their appearance after cell growth arrest. This amplifying action could be obtained whatever the time of drug addition to the cells and required the continuous presence of the drug. HFD action was strictly dependent on the presence of TH. Within the active concentration range (0.01-0.25 mM) in serum-containing medium, HFD moderately down-modulated the nuclear TH receptor level (and c-erb alpha mRNA abundance), this being additive to the known maximal but partial down-regulation provoked by TH. The results strengthen the TH obligatory role for Ob 17 cell differentiation and give arguments against a TH-like role of HFD. In this cell line, HFD mainly behave as amplifiers for the expression of lipogenic phenotypes in already committed cells.

Adipose Tissue↗
PubMed1993

Interaction of the peroxisome-proliferator-activated receptor and retinoid X receptor.

The rat peroxisome-proliferator-activated receptor (PPAR) was expressed in insect cells and was shown to bind to a cognate PPAR response element (PPRE) from the acyl-CoA oxidase gene. Upon purification, PPAR was no longer able to bind DNA, although binding could be restored by addition of insect cell extracts. We investigated whether the retinoid X receptor (RXR) could supplement for this accessory activity. The rat RXR alpha cDNA was cloned and it was found that addition of in vitro-translated RXR alpha to purified PPAR facilitated binding of PPAR to a PPRE. Furthermore, an additional activity, which appeared to be distinct from rRXR alpha, was found in COS cell nuclear extracts that enabled binding of PPAR to a PPRE. Transient expression of RXR alpha in CHO cells was found to be essential for the response of a chloramphenicol acetyltransferase reporter construct containing PPREs to activators of PPAR. These results raise the possibility of convergence of the PPAR and retinoid-dependent signaling pathways on promoters containing PPRE-like responsive elements.

Amino Acid Sequence↗
PubMed1993

Analysis of c-erb A RNA expression in the triiodothyronine-sensitive Ob 17 preadipocyte cell line.

The protooncogenes erb A alpha and beta encode, in the rat, three functional thyroid hormone receptors (erb A alpha 1, beta 1 and beta 2), and two isoforms (erb A alpha 2, alpha 3) that do not bind triiodothyronine (T3). We previously reported on a mouse preadipocyte cell line (Ob 17) which was found to be sensitive to thyroid hormones and retinoic acid. Using antibodies or cDNA probes, we reported that the c-erb A products are mainly of the alpha-type in these cells. We also showed that the thyroid hormone receptors/c-erb A products are down-regulated moderately by T3 and strongly by retinoic acid added to the culture medium. In this work, different c-erb A subtypes are identified in this mouse cell line. Using couples of oligonucleotides known to be specific of each rat c-erb A subtype, we could detect the presence of alpha 1, alpha 2 and beta 1-type transcripts. We also detected Rev transcripts of a Reverse erb A alpha gene present in the rat at the c-erb A alpha locus and that contains a region complementary to the c-erb A alpha 2-specific region. These transcripts were identified by PCR amplification from cell cDNAs and in Northern analyses using the corresponding PCR-designed c-erb A probes. All the detected transcripts were found to be down-regulated by retinoic acid.

Adipose Tissue↗
PubMed1992

Retinoic acid decreases nuclear triiodothyronine receptor expression and impairs an early step of adipose differentiation in the thyroid hormone-sensitive mouse Ob 17 preadipocyte cell line.

In the murine preadipocyte cell line Ob 17, T3 is known to be necessary at an early step of adipose differentiation for the expression of late phenotypes [lipogenic enzymes such as malic enzyme, glycerol-3-phosphate dehydrogenase (GPDH), etc.] and not necessary for the expression of lipoprotein lipase (LPL), which emerges earlier, at growth arrest. These cells contain nuclear T3 receptors, which mainly belong to products of the c-erbA alpha gene and are down-regulated by T3. In this work, retinoic acid (RA) added to Ob 17 cells at growth arrest impaired morphological differentiation and the development of both late (malic enzyme and GPDH) and early (LPL) phenotypes regardless of whether T3 was added. T3 sensitized the cells to the inhibitory action of RA; the ED50 for GPDH activity was shifted from 0.5 microM to 3 nM in cells cultured with 1.5 nM T3. Later addition of RA (6 days after growth arrest) did not inhibit the differentiation. RA also brought out a marked and fast decrease in nuclear T3 receptors. This was observed whatever the stage of cell development and related to both a rapid decrease in the relative abundance of c-erbA alpha-related mRNA species and an increased disappearance rate, suggesting the involvement of pre- and posttranslational events. RA and T3 acted additively in decreasing the T3 receptor and c-erbA alpha mRNA levels. The effects of RA on T3 receptors were rapidly reversed after RA withdrawal; the reversal was large (75%) when RA was introduced at growth arrest and total when introduced later. The cell sensitivity to RA, considering the T3 receptors, was higher at growth arrest (ED50 for RA, 0.2 and 1.5 microM in assays with RA added at growth arrest and 5 days later, respectively). The results suggest intricated regulatory pathways between RA and T3 at an early step of adipose differentiation and also suggest that among different mechanisms through which RA may impair this differentiation, a decreased level of nuclear T3 receptors at an early period should play a role.

ATP Citrate (pro-S)-Lyase↗
PubMed1991

Developmental and thyroidal regulation of the nuclear T3 receptors/c-erb A oncogene products in the Ob 17 preadipocyte cell line.

In a thyroid hormone-sensitive mouse preadipocyte cell line (Ob 17), the concentration of nuclear T3 receptors increases during differentiation in an insulin-independent manner and decreases by 50-60 p.cent after medium supplementation with physiological concentrations of T3. The down-regulation of T3 receptors implies both quantitative and qualitative changes. The preadipocyte T3 receptors were previously reported to be heterogeneous in gel filtration and in their reactivity towards rabbit antibodies raised against large erb A alpha peptides. This report shows that the receptor heterogeneity is not modified during cell development, whereas T3 mainly depletes the receptor species that are both the most retarded in gel filtration and preferentially recognized by c-erb A alpha-specific antisera. The c-erb A alpha-related T3 receptors which predominate in preadipocytes, are thus probably mainly involved in receptor depletion by T3. A similar T3 receptor half-life of 12-13 h was estimated after cycloheximide addition to cells at confluence or later in the differentiation phase with or without T3. This suggested that development, or T3, might have mainly affected the production of T3 receptors. In Northern hybridization studies, using alpha- or beta-type c-erb A cDNA probes containing the entire coding sequence, only alpha-type mRNAs were detected with a predominant band of 2.8 kbases and two fainter bands of about 5.5 and 6.0 kbases. The alpha-type mRNA abundance relative to beta-actin significantly increased during differentiation and decreased after T3 addition.

Adipose Tissue↗
PubMed1991

[Retinoic acid reduces the expression of nuclear receptors of triiodothyronin and inhibits an early stage of the differentiation in the Ob 17 preadipocytic strains].

In the murine preadipocyte cell line Ob 17, T3 is known as being necessary at an early step of adipose differentiation for the expression of late markers, but not necessary for the expression of early markers. These cells contain nuclear T3 receptors (RT3) which are products of c-erb A alpha proto oncogenes, and are down-regulated by T3. In these cells, retinoic acid (AR) inhibits the adipose differentiation and the expression of early and late markers, and T3 sensitizes the cells to the inhibitory action of AR. We also show that AR down-regulates the expression of RT3 at both pre- and post-translational levels. This inhibition is dependent on AR concentration, a peculiar sensitivity to AR being observed at an early step of development.

Adipose Tissue↗
PubMed1990

Distal trisomy 14q. I. Clinical and cytogenetical studies.

Two cases of de novo duplication of the distal part of the long arm of chromosome 14 are reported. In one case, the partial trisomy of 14q is due to translocation of a segment (14q24 to 14qter) at the end of the satellite stalk of chromosome 14. The clinical picture is very severe. In the second case, a tandem duplication in 14 (q23----q32) is present with only minor malformations and mild mental retardation.

Chromosome Banding↗