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P Reboul

Publications and source records attributed to P Reboul.

33 records · Page 2Linked to original sources
PubMed1996

Study of O-sialylation of glycoproteins in C6 glioma cells treated with retinoic acid.

When treated with retinoic acid in vivo, C6 glioma cells show an enhancement of CMP-Neu5Ac:Gal beta 1-3 GalNAc-R alpha-2,3 sialyltransferase activity. A 300 kDa glycoprotein was detected by lectin affinoblotting in retinoic acid-treated C6 cells which stained weakly or not at all in control cells. Comparative studies with different lectins demonstrated that this glycoprotein contains alpha 2,3 Neu5Ac Gal-GalNAc O-glycan moieties. Cultures in the presence of an inhibitor of O-glycan synthesis (N-acetylgalactosaminide alpha-O-benzyl) demonstrated that enhancement of staining of the 300 kDa glycoprotein was not due to the increase of the alpha 2,3 sialytransferase but to the de novo synthesis of the polypeptide chain of this glycoprotein.

Animals↗
PubMed1996

IGF and IGF-binding protein system in the synovial fluid of osteoarthritic and rheumatoid arthritic patients.

Various arthritic disorders result from a disruption of the equilibrium between the synthesis and degradation of tissue matrix macromolecules. Growth factors, particularly insulin-like growth factor-I (IGF-I), are believed to play an important role in maintaining this equilibrium. In this study, we determined the levels of IGF-I, IGF-II, and characterized and measured the amount of IGF-binding proteins (IGFBPs) in the synovial fluid (SF) of osteoarthritis (OA), rheumatoid arthritis (RA) patients and normal individuals. Furthermore, we characterized the IGFBP found in these SFs. The levels of IGF-I, IGF-II and IGFBP-3 were determined by specific radioimmunoassays (RIAs). IGFBP identification and measurement were carried out using the Western ligand blot (WLB) technique, and characterization performed by Western immunoblot. IGFBP-3 proteolysis was analyzed by autoradiography after incubation of SF with radiolabeled IGFBP-3. Results showed a statistically significant increase (P < 0.001) in the IGF-I level in arthritic SF vs normal controls; 75 +/- 11 ng/ml and 82 +/- 11 ng/ml were recorded for RA (N = 8) and OA (N = 10), respectively, whilst normal controls (N = 9) were at 19 +/- 7 ng/ml. No difference in the level of IGF-II was recorded between the three groups studied. Human SF demonstrated the presence of IGFBP-1, -2, -3 and -4, but not that of IGFBP-5 and -6. The level of IGFBP-3 tested either by WLB or RIA was significantly higher (P < 0.001) in RA and OA patients. Moreover, a statistical and positive correlation between the levels of IGF-I and IGFBP-3 was noted. WLB analysis indicated that the amount of IGFBP-1 did not vary among the groups. The levels of IGFBP-2 and -4 were significantly increased (P < 0.02) solely in the RA SF. Further experiments demonstrated that a limited IGFBP-3 proteolysis occurred in human SF. Moreover, the ratio of total IGF over total bioactive IGFBPs was lower in RA (P < 0.05), and to a lesser extent in OA than normal specimens. This study showed the presence of four IGFBPs (1 4) in human SF for which the IGFBP-2, -3 and -4 were enhanced in arthritic fluid. Importantly, although proteolysis occurred in the SF, an increased amount of bioactive IGFBPs were present in arthritic SF, which may affect the bioavailability of IGF-I within the articular tissues.

Aged↗
PubMed1995

Study of retinoic acid effect upon retinoic acid receptors beta (RAR-beta) in C6 cultured glioma cells.

Using monoclonal antibodies against the RAR-alpha and RAR-beta retinoic receptors, we demonstrated that these receptors were present together in C6 glioma cells as two isoforms of 50 and 55 kDa. For RAR-beta, the 50 kDa isoform predominated (60 to 80% of the total of the two isoforms). After a treatment for 48 h with retinoic acid 10 microM, the 55 kDa form was enhanced, while no effect was observed either on RAR-alpha isoforms from C6 cells and on both RAR-alpha and RAR-beta forms from neuroblastoma SKN SH SY5Y used as a control. Using purified neuronal and glial rat brain nuclei, we showed that the 55 kDa isoform from RAR-beta predominated in glial cells. These results suggest that retinoic acid treatment of C6 cells led to a partial differentiation, the enhancement of the heavy form of RAR-beta being a marker of this phenomenon.

Animals↗
PubMed1995

[Critical study of the characterization of hyperandrogenism in a group of obese women].

The authors report the hormonologic characteristics of 20 obese and hirsute women meeting the criteria for adrenaltype hyperandrogenism, suppressible by dexamethasone, without hyperprolactinemia and without any late developing partial enzyme block appearance. The laboratory profile of these women differed from that of a group of women with type 1 polycystic ovaries syndrome. In this same group obese women in whom LH/FSH ratio was below 1, there was evidence under baseline conditions of a moderate increase in testosterone and delta 4-androstenedione in relation to increased plasma levels of DHA and SDHA, plasma delta 4 and delta 5-androgen levels falling precipitalely during the dexamethasone suppression test. The ACTH stimulation test revealed greater reactivity for 17 hydroxy-pregnenolone (p < 0.001) and less for 21-deoxycortisol than in the control group of normal women (p < 0.01). The essentially adrenal origin of plasma hyperandrogenism in certain cases of obesity is discussed. Insulin could increase adrenal sensitivity to ACTH and its possible action in vivo on the activity of adrenal enzymes requires clarification. The accumulation of certain androgens in the adrenal cortex could also be responsible for dysregulation of 3 beta ol-dehydrogenase and 11-hydroxylase.

Adolescent↗
PubMed1994

[Diagnostic strategy in infertility due to hyperandrogenism. Development of a decision tree].

The detection of clinical hyperandrogenism in women presenting with infertility requires detailed hormonal investigations using the decisional plan suggested here. Initial studies including measurement of plasma androgen, gonadotrophic hormones and prolactin levels, may be sufficient to reveal an adrenal origin or pure ovarian origin. Non-tumor androgenic hypercorticism is seen classically in late-presenting enzyme deficits, but also in other situations: excessive adrenarche, hyperprolactinemia, obesity, chronic stress. The immediate Synacthene test can then eliminate diagnostic uncertainties if it leads to the discovery of appearances of 21- or 11-hydroxylase or 3 beta-ol dehydrogenase blocks. Intense virilisation in a woman with a testosterone level above 2 ng/ml (7 nM/l) should lead to suspicion of an androgen-secreting tumor of the ovary or adrenal. CT scan of the abdomen and true pelvis is essential here since it may reveal the presence of an adrenal or ovarian mass. If no morphological abnormality is shown by this investigation, an endocrine lesion of a small ovary should be strongly suspected, the demonstration of which requires isotope techniques and/or catheterisation of the ovarian veins. Two situations also exist which are responsible for severe hyperandrogenism but less alarming in terms of their course and significance: certain homozygous forms of 21-hydroxylase deficit diagnosed late and ovarian hyperthecosis. It may happen that these hormonal investigations do not suffice alone to determine the precise origin of hyperandrogenism and its cause. The dexamethasone adrenal suppression test is useful in the diagnosis of type II micropolycystic dystrophy, in order to define the essentially ovarian, adrenal or mixed origin of hyperandrogenism.

Adrenal Hyperplasia, Congenital↗
PubMed1994

[Fertility disorders in 49 hyperandrogenic women desiring pregnancy. Treatment results aimed at obtaining a pregnancy in 40 hyperandrogenic infertile women and in 9 hyperandrogenic women desiring pregnancy].

The clinical and therapeutic aspects of fertility due to hyperandrogenism were studied in 49 women (40 presenting with sterility and 9 for another reason but seeking to become pregnant). Patients were divided into three main etiological groups on the basis of hormonal findings: ovarian (15 cases), adrenal (16 cases) and mixed (11 cases) hyperandrogenism. This study highlighted several points. 22% of infertile women had no cutaneous signs of hyperandrogenism and menstrual disturbances were missing in 46% of cases of adrenal hyperandrogenism. Primary infertility was seen more often in all types of hyperandrogenism (28 cases) than secondary infertility (12 cases). Secondary infertility was explained by a high early spontaneous abortion rate in hyperandrogenism (40%). This was much commoner in adrenal hyperandrogenism than in ovarian or mixed hyperandrogenism. Inducing treatment based upon a combination of dexamethasone and clomiphene citrate proved to be the most effective in these infertile women (86% pregnancy rate). The frequency of spontaneous abortions in infertility due to ovarian or mixed hyperandrogenism treated by clomiphene citrate alone can probably be explained by the persistence of hyperandrogenism.

Abortion, Spontaneous↗
PubMed1993

[Hormonal profile of idiopathic gynecomastia in young adults. Apropos of 488 cases].

Gynecomastia, a very frequent disorder, is present in almost 40% of young men. In this population the investigations often fail to find any aetiology, therefore defining idiopathic gynecomastia. The aim of this work is to compare clinical and hormonal characteristics of 488 subjects with gynecomastia to 41 healthy controls. Their are many explanations for the occurrence of idiopathic gynecomastia, including modification of hormonal balance, change of aromatase activity, or a receptor anomaly. Our works demonstrate a significant decrease in mean testosteronemia, linked to a high prevalence of incipient hypogonadism in the studied population, especially in patients with an history of testicular disease.

Adolescent↗
PubMed1992

Study of O-glycan sialylation in C6 cultured glioma cells: regulation of a beta-galactoside alpha 2,3 sialyltransferase activity by Ca2+/calmodulin antagonists and phosphatase inhibitors.

We have demonstrated that the alpha 2,3 sialyltransferase (alpha 2,3 ST) from C6 cultured glioma cells was inhibited in vivo by W-7 and related Ca2+/Calmodulin (Ca/CaM) antagonists while protein kinase C effectors had no effect. Dephosphorylation of alpha 2,3 ST by the wide specificity alkaline phosphatase led to inactivation indicating that the enzyme is phosphorylated. The serine/threonine protein phosphatase inhibitors okadaic acid and Calyculin A led also to an inhibition of alpha 2,3 ST activity. In addition, Ca/CaM antagonists and phosphatase inhibitors led both to an inhibition of a alpha 2,3 sialoglycoprotein from C6 glioma cells as demonstrated with lectin affinity blotting. A concerted regulatory mechanism with phosphorylation/dephosphorylation of alpha 2,3 ST is then postulated.

Animals↗
PubMed1992

[Adrenal enzymatic block with late-onset caused by 11-hydroxylase deficiency. Apropos of 29 cases].

Late-onset congenital adrenal hyperplasia is a cause of a spectrum of clinical manifestations of postnatal androgen excess. In these cases, ACTH stimulation test with measurement of 17-Hydroxyprogesterone (17OHP) is usually done to assess 21-hydroxylase (21-OH) deficiency. Determination of the 11-deoxycortisol (S) and the S to cortisol ratio is rarely done, so that 11 beta-hydroxylase (11-OH) deficiency seems unusual. We systematically investigated this biosynthetic defect among women complaining of hyperandrogenism (n = 519) and, comparing the patient's hormonal responses to ACTH with those of 31 normal women, found 29 11-OH deficiency (5.6%): this is the largest group ever reported. S was elevated only 9 times, so that using this single determination, diagnosis of 20 enzymatic defects would not have been made. Only three of the patients (10%) had hypertension, even though the pathway of aldosterone was involved in 33% of cases (criteria: elevation of the ratio desoxycorticosterone to corticosterone). We also described one new patient with both 11-OH and 3-beta-hydroxysteroid dehydrogenase deficiencies. The patho-physiology is particularly interesting in these cases. It is concluded that the single research for 21-OH deficiency is inadequate among women complaining of hyperandrogenism: the screening for 11-OH deficiency should be made, even if blood pressure is normal.

3-Hydroxysteroid Dehydrogenases↗
PubMed1991

Study of O-glycan sialylation in C6 cultured glioma cells: evidence for post-translational regulation of a beta-galactoside alpha 2,3 sialyltransferase activity by N-glycosylation.

We have studied the Gal beta 1-3GalNAc-R alpha 2,3 sialyltransferase from C6 glioma cells transferring Neu5Ac from CMP-Neu5Ac onto O-glycans of glycoproteins. Using synchronized C6 glioma cells, we showed that the alpha 2,3 sialyltransferase activity was inhibited by tunicamycin to a greater extend than DNA and protein biosynthesis suggesting inhibition of N-glycosylation of this enzyme. Additional demonstration of N-glycosylation of the alpha 2,3 sialytransferase was provided through ConA-Sepharose binding. Treatment of partially purified alpha 2,3 sialytransferase by peptide-N-glycosidase F showed a significative inhibition demonstrating that N-glycan moiety is required for complete activity of the C6 glioma cell alpha 2,3 sialyltransferase.

Animals↗
PubMed1991

[Role of nocturnal hypertension in the deterioration of diabetic nephropathy].

UNLABELLED: Nocturnal hypertension (HTA), even a relative one, consequence of the change of the circadian pattern of blood pressure, may increase the whole day blood pressure in diabetic patients. MATERIALS AND METHODS: blood pressure has been measured every 15 minutes for 24 hours in 101 diabetic patients (43 insulin-dependent: type 1, 58 non insulin-dependent: type 2) by ambulatory blood pressure monitoring. 39 of them are hypertensive patients. Among these 101 patients, 19 have a nocturnal relative HTA corresponding in a lack or a negative difference between the diurn and the nocturn systolic or diastolic pressure (Group 1). The Group 2 is constituted by the 82 other patients; 24 hour-microalbuminuria was assayed by immunoturbidimetry for two days on end. RESULTS: patients of Group 1 were significantly older (p less than 0.01) than in the Group 2 (61 +/- 9 years vs 54 +/- 13 years). There was no significant change between the two Groups concerning the kind of diabetes (type 1 or type 2), the glycosylated hemoglobin and the frequency of degenerative complications. Microalbuminuria was significantly higher (p less than 0.01) in Group 1 (72 +/- 104 mg/24 h) than in Group 2 (20 +/- 30 mg/24 h). Both nervous dysautonomic cardiac failure and HTA treated were significantly higher in Group 1 than in Group 2, respectively (14/19 vs 28/82; p less than 0.01) and (15/19 vs 24/82; p less than 0.001). The causal blood pressure measurement was similar in the two Groups, but the whole day ambulatory blood pressure monitoring revealed a significant increase of the average of systolic (Group 1: 133 +/- 14 mmHg vs Group 2: 119 +/- 12 mmHg; p less than 0.001) and diastolic (Group 1: 81 +/- 12 mmHg vs Group 2: 75 +/- 8 mmHg; p less than 0.01) blood pressure during 24 hours. COMMENTS: the causal blood pressure measurement fails to appreciate the increase of the whole day blood pressure consequent to the suppression of nocturnal hypotension and sometimes to the occurrence of real nocturnal hypertension. This observation is probably in relation with the nervous dysautonomic cardiac failure and is associated with an increase of the microalbuminuria (patients with microalbuminuria greater than 30 mg/24 h--Group 1: 9/19 vs Group 2: 17/82; p less than 0.05). This situation can lead to an aggravation of degenerative complications. Such results should urge practitioners to assess the circadian pattern of blood pressure in diabetic patients more accurately.

Aged↗
PubMed1990

Effect of retinoic acid on two glycosyltransferase activities in C6 cultured glioma cells.

1. Activity of two glycosyltransferases was studied in retinoic acid-treated C6 cultured glioma cells. 2. The beta-galactoside alpha 2,3-sialyltransferase transferring N-acetylneuramin onto the O-glycans residues of glycoproteins was activated up to twice after chronic treatment (from 24 to 96 hr) with all-trans retinoic acid. 3. No effect was observed for shorter treatments. 4. On the opposite, the N-glycan galactosyltransferase activity remained unchanged whatever the length of retinoic acid treatment was. 5. The activatory effect was not dependent on isomery, as all-trans and 13-cis retinoic acid isomers were both activators of the C6 glioma cell sialyltransferase. 6. Measurement of adhesion of retinoic acid-treated cells using labelled plasma membranes showed an enhancement of adhesion in correlation with enhancement of sialyltransferase activity.

Animals↗
PubMedDate not supplied

[Citalopram. An open study of a highly selective serotonin-uptake inhibitor administered by infusion to depressive patients].

In an open, clinical trial comprising a total of 49 depressed in-patients, a new selective 5-HT uptake inhibitor citalopram was administered by intravenous infusion in doses of 20-60 mg once daily for per 3 weeks. The therapeutic effect was assessed globally and by means of the CPRS subscale for depression (MADRS). About 40 per cent of the patients showed a complete response whereas about 25 per cent showed a partial response. Side effects which were rated globally and recorded according to a check-list were generally mild and infrequent. The side-effects most frequently observed were tremor, drowsiness, and dizziness which occurred in about 15 per cent of the patients.' Three patients were withdrawn prematurely because of nausea and one because of a skin rash. Cardiovascular recordings were normal except for one patient, who developed a hypertension which may have been related to the test drug. No pathological laboratory values were detected during the trial period. The authors conclude that intravenously administered citalopram is well suited for the treatment of depressed patients.

Adult↗