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Biomedical subjects

A Fournier

Publications and source records attributed to A Fournier.

At least 181 records · Page 10Linked to original sources
PubMed1997

High level of transgene expression in cell cultures and in the mouse by replication-incompetent adenoviruses harboring modified VAI genes.

Replication-incompetent adenoviruses are currently used in gene therapy trials. Most of the work designed to increase the expression from these vectors concerns the modification of cis sequences of the foreign transcription unit, so as to improve the transcription level or the stability of the mRNA. In this report, we show that an alternative strategy based on the coexpression of modified VAI genes can efficiently increase gene expression both in cell cultures and in animals. The VAI RNA is synthesized mainly during the late phase of the adenovirus cycle and increases the translation of late adenovirus gene products by counteracting the effect of an interferon-induced kinase, the PKR. We have constructed several modified VAI genes in which the central domain was deleted or substituted by exogenous sequences. These modified VAI genes, or the native VAI gene, were cloned into the left part of adenovirus type 5 genomes harboring their own endogenous VAI gene. One of the resulting viruses (Ad-VAr) increased 12.5- to 502-fold the expression level of reporter genes, either expressed as a constitutive cell line from an extrachromosomal DNA or introduced into cells by coinfection with another adenovirus vector. This effect was independent of the promoter, the coding sequence, and the 5' untranslated mRNA sequence and was obvious in the two non-E1-complementing cell lines tested (HeLa and Vero). Coinfection of Ad-VAr with adenoviruses expressing the luciferase gene from the major late promoter or Rous sarcoma virus (RSV) promoter by the intravenous route in mice increased by more than 33 (MLP)- to 128 (RSV)- and 4,700 (MLP)- to 30,000 (RSV)-fold the expression level of the reporter gene in the lungs and liver, respectively. The intramuscular coinoculation of Ad-VAr and Ad-MLP-gD (a recombinant adenovirus vaccine expressing gD from the pseudorabies herpes virus) led to a 10-fold decrease in the protective dose of Ad-gD in mice. Ad-VAfull, a similar adenovirus in which the native VAI gene was cloned at the left part of the genome, showed no evidence of efficacy in cell culture and in mice. These results suggest that the use of modified VAI genes expressed at the early phase of the cycle can be helpful in the design of potent adenovirus vectors.

Adenoviridae↗
PubMed1997

Effect of endothelin-1 on corticosteroid secretion by the frog adrenal gland is mediated by an endothelinA receptor.

We have previously reported that endothelin-1 (ET-1) stimulates the in vitro secretion of corticosterone and aldosterone from the adrenal gland of the frog Rana ridibunda. The aim of the present study was to investigate the pharmacological profile of the endothelin receptor subtype involved in the corticotropic effect of ET-1. The mixed ET(A)/ET(B) receptor antagonist Ro 47-0203 (10(-5) M) totally blocked the stimulatory effect of ET-1 (5 x 10(-9) M) on corticosterone and aldosterone secretion. The action of ET-1 was also inhibited by the selective ET(A) receptor antagonist BQ-485 (10(-7) M). In contrast, the selective ET(B) receptor antagonist IRL 1038 (10(-6) M) did not affect the response of the frog adrenal gland to ET-1. In addition, the selective ET(B) receptor agonist IRL 1620 (10(-6) M) did not mimic the stimulatory effect of ET-1. The high affinity ET(C) receptor agonist endothelin-3 (ET-3) stimulated corticosteroid secretion, but was 400 times less potent than ET-1. Moreover, the action of ET-3 was also blocked by BQ-485 (10(-7) M). These data indicate that the stimulatory effects of ET-1 and ET-3 on corticosteroid secretion by the frog adrenal gland are mediated by an ET(A) receptor subtype.

Adrenal Cortex Hormones↗
PubMed1997

Low bone mineral density and peripheral blood monocyte activation profile in calcium stone formers with idiopathic hypercalciuria.

Calcium stone formers (CaSF) with idiopathic hypercalciuria (IH) have been shown to have decreased bone mineral density (BMD). The mechanism of their bone loss remains obscure. Monokines like interleukin-1 beta (IL-1 beta), IL-6, tumor necrosis factor-alpha (TNF-alpha), and granulocyte macrophage stimulating factor (GM-CSF) are involved in bone remodeling, but only IL-1 excess has been incriminated in the bone loss of CaSF with IH. Therefore, to more precisely delineate the role of monocyte activation in the pathogenesis of bone loss in these patients, we studied the production of IL-1 beta, IL-6, TNF-alpha, and GM-CSF by unstimulated or lipopolysaccharide (LPS)-stimulated cultured peripheral blood monocytes in 15 CaSF with IH, in 10 CaSF with dietary calcium-dependent hypercalciuria (DH), and in 10 healthy controls (C). Cytokines were measured in the culture medium by sensitive enzyme-linked immunosorbent assay and vertebral BMD by single energy computed tomography. The decrease of vertebral BMD in IH compared with DH, was confirmed (Z score: -1.2 +/- 0.2 vs. -0.5 +/- 0.2; P = 0.04; Mann-Whitney). In the supernatant of unstimulated peripheral blood monocytes, IL-1 beta and TNF-alpha levels were higher in IH than in C (respectively, 40 +/- 21 vs. 7 +/- 1 pg/mL, P = 0.008 and 236 +/- 136 vs. 39 +/- 23 pg/mL, P = 0.03); those of GM-CSF were greater in IH than in DH and C (respectively, 52 +/- 27 vs. 6 +/- 2, P = 0.04 and 6 +/- 2 pg/mL, P = 0.01) and those of IL-6 were not significantly different among the groups. After in vitro stimulation by LPS (10 micrograms/mL), the levels of the various monokines were not significantly different. In IH patients, the post-LPS levels of IL-6 were negatively correlated to vertebral BMD (n = 15, Z = -1.97, P = 0.04; Spearman), whereas those of GM-CSF were positively related to vertebral BMD (n = 15, Z = 2.01, P = 0.04). In this study, calcium stone formers with IH have bone mineral decrease and a particular profile of peripheral blood monocytes activation. This latter is characterized by a spontaneously increased synthesis of IL-1 beta, TNF-alpha, and GM-CSF. Furthermore, post-LPS levels of IL-6 and GM-CSF are correlated with vertebral BMD. These results suggest that monocyte activation may be involved in the bone loss of calcium stone formers with IH.

Adult↗
PubMed1997

[Relative depletion in native vitamin D: a potential risk factor in Algerian hemodialysis patients with radiological evidence of hyperparathyroidism and osteomalacia independent of calcitriolemia].

Looser striae on the ischio-pubian branches and subperiosteal resorption of the phalanges were looked for in 113 chronic hemodialysis patients at the University Hospital of Annaba (Algeria) and were found in respectively 14 and 48 patients. Comparison of patients with and without radiological complications showed no significant difference in their age, sex ratio, nature of initial kidney disease and duration on dialysis. The patients with Looser striae had lower plasma levels of 25OHD3 than those without striae, whereas all other plasma parameters were similar. The plasma concentrations of intact PTH were higher in patients with resorption; these patients had lower plasma concentrations of calcium, bicarbonate, aluminum and 25OHD3 but similar plasma concentrations of phosphate and 1,25(OH)2D3. Multivariate analysis showed that PTH concentrations were independently linked only to plasma 25OHD3 (negatively) and duration on dialysis (positively). The results of this transversal study are in agreement with the well established pathophysiological roles of PTH hypersecretion, hypocalcemia and acidosis in the appearance of radiological hyperparathyroidism in hemodialysis patients. Furthermore they suggest that a relative native vitamin D deficiency may have a calcitriol independent role in favoring the occurrence of both osteitis fibrosa and osteomalacia.

Adult↗
PubMed1997

[Transesophageal echographic demonstration of ulcerated atheromatous plaques of the thoracic aorta responsible for cholesterol emboli].

The authors present of case of a 61-year-old man suffering from cholesterol emboli, in whom transoesophageal echocardiography revealed complex atheromatous lesions of the thoracic aorta. There is growing emphasis, at the present time, on the concept of triggering factors with the multiplication of endovascular radiological investigations, the more widespread availability of cardiac surgery and the use of anticoagulants and fibrinolytics. The prognosis is poor, treatment is only palliative and preventive measures are therefore essential.

Aorta, Thoracic↗
PubMed1997

Migration and development of mother sporocysts of Echinostoma caproni (Digenea: Echinostomatidae).

Experimental infections of the mollusc Biomphalaria pfeifferi by Echinostoma caproni miracidia (Mi) were carried out in order to analyze the migration and development of mother sporocysts (MS) at 26 C. Miracidia penetrated different parts of the host's body, such as the mantle collar, the foot and head covering (including velum and tentacles), the mantle cavity, and the oral cavity. The ventricle and common aorta were the final sites of infection for the mother sporocysts after migration. The path of migration of the sporocyst was influenced by the point of MS penetration, but in all cases the MS reached the ventricle through the venous system. Developmental studies showed that newly hatched Mi contained 5-7 germinal cells (the primary germinal cells) and some undifferentiated cells. During sporocyst development, every primary germinal cell apparently gave rise to a redial embryo, whereas undifferentiated cells gave rise to both somatic and secondary generative cells. The eventual degeneration of the sporocyst seemed to cause the end of the development of this germinal material. The MS produced about 15 mother rediae (MR). Intramolluscan development of E. caproni MS consisted of 5 main periods: (1) resting, (2) migration, (3) growth, (4) reproduction, and (5) degeneration. A lower temperature of 21 C affected the duration of each stage. However, the path of sporocyst migration, the pattern of their growth, and the developmental steps of the germinal material were similar.

Animals↗
PubMed1997

A potent and selective CGRP2 agonist, [Cys(Et)2,7]hCGRP alpha: comparison in prototypical CGRP1 and CGRP2 in vitro bioassays.

The development of highly selective and potent agonists and antagonists is critical in evaluating the physiological role(s) of each receptor subtype in a peptide family. The existence of at least two calcitonin gene related peptide (CGRP) receptor subtypes has been proposed based on the potency of CGRP8-37 to antagonize the effect of hCGRP alpha in the guinea pig atrium and the agonistic properties of the linear analogue [Cys(Acm)2,7]hCGRP alpha to mimic the effect of hCGRP alpha in the rat vas deferens. However, the rather low potency of [Cys(Acm)2,7]hCGRP alpha (ED50 = 82 +/- 7.5 nM) to activate the CGRP2 receptor subtype limits its usefulness. Accordingly, we investigated various structural modifications of this linear analogue in prototypical CGRP1 and CGRP2 in vitro bioassays. Among them, replacing the acetaminomethyl moiety (Acm) by an ethylamide group, [Cys(Et)2,7]hCGRP alpha demonstrated a high potency to inhibit the rat vas deferens twitch response (ED50 = 3.4 +/- 1.2 nM), whereas in the guinea pig atrium, this analogue induced only a slight inotropic effect at very high concentrations (1 microM). Moreover, [Cys(Et)2,7]hCGRP alpha as well as the addition of a tyrosine residue at the N-terminal, [Tyr0,Cys(Et)2,7]hCGRP alpha, competed with high affinities for [125I]hCGRP binding in rat brain homogenates (IC50 = 0.3 and 0.1 nM, respectively). Taken together, these results suggest that [Cys(Et)2,7]hCGRP alpha is a new potent analogue that could prove valuable in addressing the functional relevance of the CGRP2 receptor class.

Animals↗
PubMed1997

Effect of neuropeptide Y on bradykinin-induced release of prostacyclin and thromboxane from guinea pig perfused lung.

We have previously reported that neuropeptide Y (NPY) inhibits responses induced by various agonists (noradrenaline, vasoactive intestinal peptide, substance P,5-hydroxytryptamine) in isolated guinea pig trachea. Although the underlying mechanisms have not been fully characterized, it was found that the NPY-evoked inhibition was specifically expressed with agents for which locally released prostaglandins (PGs) are important determinants for their myotropic activity. In the present study, we have extended these findings by examining whether NPY was capable of regulating the release of prostacyclin and thromboxane A2 induced by bradykinin (BK) from naive and ovalbumin-sensitized guinea pig perfused lungs. Our results showed that infusion of NPY (0.24 microM) through the lung significantly inhibited the release of 6-keto-PGF1 alpha (> 30%) and thromboxane B2 (50%) induced by intraarterial administration of BK (3 micrograms) from untreated and ovalbumin-sensitized guinea pig perfused lung. However, the inhibitory effect of NPY was lost in the immunological production of prostaglandins. These results suggest that NPY may act as a regulatory agent of the release of cyclooxygenase-derived products by possibly acting on events preceding phospholipase A2 activation.

6-Ketoprostaglandin F1 alpha↗
PubMed1997

[Thrombotic thrombocytopenic purpura and hemolytic-uremic syndrome in adults. Apropos of 27 cases].

UNLABELLED: We report a series of 27 patients included on the basis of either thrombotic microangiopathy (TMA) at renal histology (13 cases) or, in the absence of histology, non-immunological hemolytic anemia with schizocytes and thrombopenia (14 cas). The etiopathogenic treatment consisted in the administration of antiagregating agents (in all patients except 3 of group I because of the severity of thrombopenic), corticosteroids (1 case), intravenous immunoglobulins (2 cases) fresh frozen plasma (FFP) without plasma exchange (PE) in 7 cases and PE with FFP in 13 patients. According to the 6 months outcome, 4 groups were considered I: death due to neurological damage; II: chronic hemodialysis; III: partial renal recovery; IV: complete renal recovery. COMMENTS AND CONCLUSIONS: a/Patients with neurological complications have poor prognosis in spite of minor renal involvement and use of PE whose indication is validated in these cases. b/When renal involvement predominates, accelerated hypertension is linked to arteriolar or mixte type of TMA, exposes to an increased risk of hemorrhagic complications of the renal biopsy (4 out fo 5) which questions the usefulness of such biopsy (group II). c/TMA may precede cancer. It has per se a favorable outcome even when metastases are already present, warranting aggressive treatment.

Adolescent↗
PubMed1996

Occurrence of two somatostatin variants in the frog brain: characterization of the cDNAs, distribution of the mRNAs, and receptor-binding affinities of the peptides.

In tetrapods, only one gene encoding a somatostatin precursor has been identified so far. The present study reports the characterization of the cDNA clones that encode two distinct somatostatin precursors in the brain of the frog Rana ridibunda. The cDNAs were isolated by using degenerate oligonucleotides based on the sequence of the central region of somatostatin to screen a frog brain cDNA library. One of the cDNAs encodes a 115-amino acid protein (prepro-somatostatin-14; PSS1) that exhibits a high degree of structural similarity with the mammalian somatostatin precursor. The other cDNA encodes a 103-amino acid protein (prepro-[Pro2, Met13]somatostatin-14; PSS2) that contains the sequence of the somatostatin analog (peptide SS2) at its C terminus, but does not exhibit appreciable sequence similarity with PSS1 in the remaining region. In situ hybridization studies indicate differential expression of the PSS1 and PSS2 genes in the septum, the lateral part of the pallium, the amygdaloid complex, the posterior nuclei of the thalamus, the ventral hypothalamic nucleus, the torus semicircularis and the optic tectum. The somatostatin variant SS2 was significantly more potent (4-6 fold) than somatostatin itself in displacing [125I-Tyr0, D-Trp8] somatostatin-14 from its specific binding sites. The present study indicates that the two somatostatin variants could exert different functions in the frog brain and pituitary. These data also suggest that distinct genes encoding somatostatin variants may be expressed in the brain of other tetrapods.

Amino Acid Sequence↗
PubMed1996

Effects of pituitary adenylate cyclase-activating polypeptide (PACAP) on gonadotropin-releasing hormone and somatostatin gene expression in the rat brain.

Pituitary adenylate cyclase-activating peptide (PACAP) is a 38-amino acid polypeptide, first isolated from ovine hypothalamus, which directly stimulates the release of several pituitary hormones, including GH, ACTH, and LH. The presence of PACAP receptors in several brain areas, including the hypothalamus, suggests that this peptide might play a role as neurotransmitter/neuromodulator. We have thus investigated the effects of intracerebroventricular (i.c.v.) and intravenous (i.v.) injections of PACAP and the potent PACAP antagonist PACAP(6-38) on gonadotropin-releasing hormone (GnRH) and somatostatin (SS) gene expression in the male rat hypothalamus. The levels of mRNA were measured at the cellular level by quantitative in-situ hybridization. The i.c.v. injection of PACAP produced a 12.5% increase in the GnRH mRNA levels, an effect which was completely prevented by the concomitant administration of the PACAP antagonist. The administration of the PACAP antagonist induced by itself a 12.9% decrease in the hybridization signal. The i.v. administration of the same peptides induced modifications in GnRH gene expression which were completely opposite to those produced by i.c.v. administration. In somatostatinergic neurons located in the periventricular nucleus, the i.c.v. injection of the peptides induced modification in SS gene expression which were very similar to those observed for GnRH gene expression, although the changes were less striking. The i.v. administration of PACAP or its antagonist did not induce any change in the levels of SS mRNA. These results then strongly suggest that PACAP might be involved in a positive regulation of two neuropeptides involved in the control of anterior pituitary secretion via central specific receptors. The inverse influence of PACAP on GnRH gene expression after the i.v. injection might be explained by the short feedback effect induced by the direct stimulation of gonadotropin hormone release following the systemic injection of the peptide.

Animals↗
PubMed1996

Characterization of the receptor mediating the effect of calcitonin gene-related peptide in the frog adrenal gland.

We have recently reported the presence of calcitonin gene-related peptide (CGRP)-containing nerve fibers in the frog adrenal gland and we have shown that CGRP is a potent stimulator of corticosterone and aldosterone secretion by adrenocortical cells. The aim of the present study was to characterize the type of receptors mediating the effect of CGRP in the frog adrenal gland. Amylin and adrenomedullin, two members of the CGRP family, induced a weak stimulation of corticosterone and aldosterone secretion from perifused frog adrenal slices. In contrast, salmon and human calcitonin had no effect on corticosteroid secretion. Administration of the type-1 CGRP receptor antagonists human CGRP-(8-37) and human CGRP-(19-37) did not significantly affect the secretory response induced by frog CGRP. Concurrently, the type-2 CGRP receptor agonist [acetamidomethyl-Cys2,7]human CGRP ([Cys(ACM)2,7]human CGRP) provoked a dose-dependent stimulation of corticosterone and aldosterone secretion (EC50 = 1.6 x 10(-7) M). Both frog CGRP and [Cys(ACM)2,7]human CGRP induced a significant increase in cAMP production by frog adrenal tissue. These data indicate that, in the frog adrenal gland, the stimulatory effect of CGRP is mediated through activation of a type-2 CGRP receptor positively coupled to adenylyl cyclase.

11-Hydroxycorticosteroids↗
PubMed1996

The H295R human adrenocortical cell line contains functional atrial natriuretic peptide receptors that inhibit aldosterone biosynthesis.

The inhibitory effect of atrial natriuretic peptide (ANP) on angiotensin II (AII)-stimulated aldosterone secretion has been previously studied in rat and bovine adrenal zona glomerulosa cells in primary culture. However the understanding of the mode of action of ANP at the molecular level has been hampered by limitations of those primary cell culture systems and by the lack of cell lines from human adrenal cortex. Here we demonstrate the presence of fully functional ANP receptors in the recently characterized AII-responsive adrenocortical carcinoma cell line H295R. Specific saturable binding of 125I-rANP to H295R cell membrane preparations revealed a single class of high affinity binding sites with a density of 20 fmol/mg of protein. The pharmacological profile of this ANP receptor was documented by competitive binding of 125I-rANP with naturally occurring natriuretic peptides. rANP was the most potent with a Kd of 42 pM. pBNP32 was less potent with a Kd of 174 pM. 125I-rANP binding was not competed by pCNP (NPRB-specific ligand) nor by C-ANF (NPRC-specific ligand). Photoaffinity labeling of membrane preparations with 125I-BPA-ANP revealed a single specific protein of molecular weight around 130 kDa. This protein was further identified by immunodetection with a specific antibody directed to the human ANP-specific receptor NPRA. Natriuretic peptides stimulated cGMP production by the receptor-coupled guanylate cyclase with the same specificity. Aldosterone production by AII-stimulated H295R cells was dose-dependently inhibited by rANP with an ED50 of 1.5 nM. In addition, we used this model to test two chimeric analogs of ANP and BNP. pBNP1 and pBNP3 were, respectively, 4- and 2-fold more potent than rANP in competing for 125I-rANP binding with Kd of 10 and 20 pM. pBNP1 was 24-fold more potent in inhibiting AII-stimulated aldosterone production with ED50 of 63 pM. pBNP1 is therefore the most potent natriuretic peptide analog tested. In summary, the human H295R cell line contains NPRA receptors positively coupled to the particulate guanylate cyclase and that antagonize angiotensin II stimulation of aldosterone secretion.

Adrenal Cortex↗
PubMed1996

Autoradiographic distribution of [125I]Leu31,Pro34]PYY and [125I]PYY3-36 binding sites in the rat brain evaluated with two newly developed Y1 and Y2 receptor radioligands.

The peptide YY derivatives [Leu31,Pro34]PYY and PYY3-36 are highly selective Y1 and Y2 agonists, devoid of activity on the Y3 receptor subtype [Dumont et al. (1994) Molec. Brain Res., 26:3220-3324]. These selective ligands were iodinated and used to evaluate the respective quantitative autoradiographic distribution of the Y1 and Y2 receptor subtypes in the rat brain, excluding a potential contamination from Y3 receptor. Specific [125I][Leu31,Pro34]PYY (Y1), and [125I]PYY3-36 (Y2) binding sites are detected in various brain regions, but each showed a differential distribution profile. Y1/[125I][Leu31,Pro34]PYY sites are especially concentrated in superficial layers of the cortex, the olfactory tubercle, islands of Calleja, tenia tecta, molecular layer of the dentate gyrus, several thalamic nuclei, and the posterior part of the medial mammaliary nucleus. These areas generally contained only low densities of Y2/[125I]PYY3-36 binding sites. In contrast, [125I]PYY3-36 binding is most abundant in multiple other regions including the lateral septum, piriform cortex, triangular septal nucleus, bed nucleus of the stria terminalis, oriens layer and stratum radiatum of the dorsal hippocampus, ventral tegmental area, substantia nigra, dorsal raphe nucleus, and the granular cell layer of the cerebellum. Few areas of the rat brain contained significant amounts of both [125I][Leu31,Pro34]PYY and [125I]PYY3-36 binding sites such as the anterior olfactory nuclei, oriens layer and stratum radiatum of the ventral hippocampus, nucleus tractus solitarius, area postrema, and inferior olive. Taken together, these results and the use of two selective radioligands demonstrate further the discrete, differential distribution of the Y1 and Y2 receptor subtypes in the rat brain.

Animals↗
PubMed1996

Comparison of the efficacy of replication-defective adenovirus and Nyvac poxvirus as vaccine vectors in mice.

Adenovirus and poxvirus recombinant vectors are more and more used as live experimental vaccines. In order to compare the efficacy of these vectors to elicit serological response and protection against challenge, two recombinants carrying the same gene (pseudorabies virus gD) were used as experimental vaccines in mice, a permissive species to pseudorabies infection. Two routes were tested: intramuscular (i.m.) and intranasal (i.n.) in order to try to stimulate general and mucosal immune responses. Several doses ranging from 10(2.9) to 10(8.9) TCID50, depending on the vaccines were tested. The estimated log 10 (PD50) for the i.m. route were 7.1 +/- 0.2 for the adenovirus vector (Ad-gD), and 7.6 +/- 0.2 for the Nyvac vector (vP900). For the i.n. route, log 10 (PD50) of Ad-gD was 7.1 +/- 0.2, and was higher than 7.9 for vP900. While the adenovirus vector proved more efficient than the poxviral vector to elicit antibody response, only a slight difference was observed when comparing the survival times of animals after challenge. Adenovirus was found better only for the 10(7.9) TCID50 dose, when inoculated i.m. Intranasal vaccination appeared efficient only with the adenovirus vector for the TCID50 10(8.9) dose.

Adenoviridae↗