PubMed Health⌕ Search

Biomedical subjects

C Leroy

Publications and source records attributed to C Leroy.

At least 19 recordsLinked to original sources
PubMed1998

MView: a web-compatible database search or multiple alignment viewer.

UNLABELLED: MView is a tool for converting the results of a sequence database search into the form of a coloured multiple alignment of hits stacked against the query. Alternatively, an existing multiple alignment can be processed. In either case, the output is simply HTML, so the result is platform independent and does not require a separate application or applet to be loaded. AVAILABILITY: Free from http://www.sander.ebi.ac.uk/mview/ subject to copyright restrictions. CONTACT: brown@ebi.ac.uk

Computer Communication Networks↗
PubMed1998

[Alternative treatment of dry eyes by punctum plugs--results in 60 patients].

PURPOSE: This is an analysis assessing clinical results after treatment with punctum Plugs in dry-eye patients stubborn to usual treatment. METHOD: We analysed retrospectively data from 60 patients treated by fitting in 1 to 4 silicone plugs in canaliculi. RESULTS: This study allowed to assess the advantages and disadvantages of the method, notably according to the selection criteria of patients and to the number of plugs inserted. CONCLUSION: This revertible treatment of the dry-eye syndrome is an efficient alternative, provided that patients are judiciousely selected.

Dry Eye Syndromes↗
PubMed1997

Potassium transport in opossum kidney cells: effects of Na-selective and K-selective ionizable cryptands, and of valinomycin, FCCP and nystatin.

The effects of two ionizable cryptands, the Na-selective (221)C10 and the K-selective (222)C10, and of valinomycin, FCCP and nystatin on K+ fluxes in opossum kidney (OK) cells have been quantified. The Na,K-ATPase (ouabain-sensitive 86Rb influx) was stimulated by nystatin (> or = 20%), and inhibited by the other ionophores (50-80%), by barium (K-channel blocker) (61%) and by amiloride (Na entry blocker) (34%). The Vmax of the Na,K-ATPase phosphatase activity was unmodified by the ionophores, indicating the absence of direct interaction with the enzyme. The ATPi content was unmodified by the inhibitors and nystatin, but was lowered by (221)C10 (47%), (222)C10 (75%), valinomycin (72%) and FCCP (88%). Amiloride was found to partially remove the inhibition caused by (222)C10 (51%) and valinomycin (49%). Rb efflux was stimulated by nystatin (32%), unmodified by valinomycin, and was inhibited by (221)C10 (19%), (222)C10 (19%) and FCCP (10%). Barium (39%) and amiloride (32%) inhibited this efflux and, in their presence, the nystatin effect persisted, whereas that of the other ionophores vanished. At pH 6.4, the Rb efflux decreased by 14% of its value at pH 7.4, with no additional inhibition by cryptands. Cryptands are shown to inhibit the pH-sensitive K+-conductance, probably by inducing a K+-H+ exchange at the plasma membrane, and by uncoupling oxidative phosphorylation by inducing the entry of K+ and H+ (and possibly Ca2+) ions into the mitochondria.

Adenosine Triphosphate↗
PubMed1997

GIF-DB, a WWW database on gene interactions involved in Drosophila melanogaster development.

GIF-DB (Gene Interactions in the Fly Database) is a new WWW database (http://www-biol.univ-mrs.fr/ approximately lgpd/GIFTS_home_page. html ) describing gene molecular interactions involved in the process of embryonic pattern formation in the flyDrosophila melanogaster. The detailed information is distributed in specific lines arranged into an EMBL- (or SWISS-PROT-) like format. GIF-DB achieves a high level of integration with other databases such as FlyBase, EMBL and SWISS-PROT through numerous hyperlinks. The original concept of interaction databases examplified by GIF-DB could be extended to other biological subjects and organisms so as to study gene regulatory networks in an evolutionary perspective.

Animals↗
PubMed1997

Overexpression of ecto-5'-nucleotidase promotes P-glycoprotein expression in renal epithelial cells.

UNLABELLED: P-glycoprotein (P-gp), responsible for multidrug resistance (MDR) of tumoral cells, is also expressed in apical membranes of normal epithelial cells, among which are proximal tubular cells. Ecto-5'-nucleotidase (5'Nu), co-located with P-gp in renal brush border membranes, could be instrumental in the expression of MDR phenotype. P-gp activity [assessed by rhodamine 123 (R123) and [3H]vinblastine (3H-VBL) accumulation] was evaluated in MDCK cell lines in which human 5'Nu was expressed at different levels after retroviral infection: MDCK-5'NU/- cells with a low 5'Nu activity (Vmax < 2 pmol/mg protein/min) and MDCK-5'NU/+ cells, which expressed a high level of 5'Nu (Vmax 150 +/- 18.5 pmol/mg protein/min). MDCK-5'NU/- cells did not display functional expression of MDR. In MDCK-5'NU/+ cells, R123 and 3H-VBL accumulation was significantly lower than in MDCK-5'NU/- cells and was dramatically enhanced by P-gp inhibitors. This high P-gp activity in MDCK-5'NU/+ cells was confirmed by their resistance to colchicine (measured by LDH release and MTT assay) as compared to MDCK-5'NU/- and was accounted for by increased membrane expression of P-gp assessed by Western blot. Neither AMP nor adenosine, the substrate and the product of 5'Nu, respectively, affected P-gp activity. Inhibition of 5'Nu with alpha beta-methylene-adenosine-diphosphate (alpha beta MADP) or with a blocking anti-5'Nu antibody (1E9) did not blunt MDR expression in MDCK-5'NU/+ cells. Conversely, the anti-5'Nu antibody 5F/F9, which did not block the enzymatic site, induced a decrease of P-gp activity. Further, incubation of MDCK-5'NU/- cells with conditioned medium from MDCK-5'NU/+ cells, which contained significant amounts of released 5'Nu, induced MDR phenotype. IN CONCLUSION: (i) expression of ecto-5'Nu promotes multidrug resistance (MDR) activity in renal epithelial cells by enhancement of P-gp expression; (ii) this effect does not involve enzymatic activity of 5'Nu; (iii) supernatants of cells that express 5'Nu conferred P-gp activity to 5'Nu negative cells.

5'-Nucleotidase↗
PubMed1997

Parathyroid hormone-induced calcium release from intracellular stores in a human kidney cell line in the absence of stimulation of cyclic adenosine 3',5'-monophosphate production.

PTH-induced mobilization of cytosolic Ca2+ in a human kidney cell line (HEK/W) occurring in the absence of cAMP stimulation was characterized and compared with that obtained in the same cells stably transfected by the PTH/PTH-related peptide (PTHrp) receptor (HEK/T). In both cell lines, N-terminal fragments of PTH and PTHrp induced a concentration-dependent biphasic stimulation in [Ca2+]i: a transient peak followed by a slow linear increase. These increases in [Ca2+]i were inhibited by the PTH antagonist [Nle(8,18),Tyr(34)]bPTH(3-34). The transient peaks were due to calcium release from intracellular stores, as they resisted quenching of calcium in the extracellular buffer and were abolished by prior emptying of intracellular stores. These peaks differed, however, both in latency period and in magnitude, in the two cell lines. The phospholipase C inhibitor U73122 inhibited the PTH-induced increase in [Ca2+]i in HEK/T cells, but not in HEK/W. Similarly, PTH-induced inositol phosphate (InsPs) production was detected in HEK/T but not in HEK/W cells. PTH-induced calcium release in HEK/W cells was inhibited by the simultaneous presence of ryanodine and U73122. Low level PTH/PTHrp receptor messenger RNA expression was demonstrated by ribonuclease protection in HEK/W cells, although no specific binding of [125I]PTHrP(1-34) could be detected. Amplification products for the PTH/PTHrp receptor 1, but no other isoforms, were detected by RT-PCR in HEK/W cells. As expected, HEK/T cells responded to PTH by a 500-fold stimulation in cAMP production and expressed large numbers of PTH/PTHrp receptors, as shown by [125I]PTHrp binding. These results demonstrate that the signal transduction pathways activated by PTH in HEK/W and HEK/T cells are different. Because the major difference in these cell lines is the number of PTH/PTHrp receptors expressed, these results suggest that the transduction of signals by the PTH/PTHrp receptor is controlled by receptor number in such a way that PTH stimulates an increase in intracellular calcium in the absence of stimulation of InsPs and cAMP production in cells expressing low levels of PTH/PTHrp receptor, but stimulates calcium release through an InsPs pathway and induces cAMP production in cells expressing large numbers of PTH/PTHrp receptors. The control of receptor number may be one of the mechanisms through which PTH effects are regulated.

Calcium↗
PubMed1996

Tight connection between choline transport and phosphatidylcholine synthesis in MDCK cells.

In MDCK cells, choline uptake, the first step in the CDP-choline pathway for the biosynthesis of choline-containing phospholipids and osmolytes, occurs via both a transport system highly specific for choline and a non-specific pathway. The specific choline carrier is present at the apical domain of cells grown on dishes and is sodium-independent. Growing the cells on a permeant support results in the preferential localization of the specific choline carrier at the basolateral domain. To characterize the relationships between the choline uptake sites and the synthesis of phosphatidylcholine, MDCK cells were incubated with [Me-3H]choline and/or [Me-14C]choline for various times (up to 36 h) and the incorporation of label into phospholipids and water-soluble molecules was determined. For cells grown on dishes, addition of [Me-3H]choline at the apical side was followed by rapid incorporation of the label into the successive intermediates of the CDP-choline pathway. A comparable situation was found when growing the cells on a permeant support and adding the labelled choline at the basolateral side of the culture. On the other hand, radioactive choline added to the apical bath entered the CDP pathway to only a very low extent. Efflux experiments on cells loaded with choline from either the apical or the basolateral side demonstrate the existence of intracellular pools of choline. Addition of hemicholinium-3, an inhibitor of the specific choline carrier, markedly reduced the metabolism of choline taken up by the cells on the basolateral side but had no effect on that transported at the apical side. These results strongly suggest the existence of a tight connection between the entry of choline through the specific choline carrier and phosphatidylcholine synthesis in MDCK cells.

Animals↗
PubMed1995

[Acute necrotizing enterocolitis during a prolonged treatment with neuroleptics].

A 32-year old man treated for several years with phenothiazine for chronic psychosis developed acute necrotizing colitis. The causal relationship with neuroleptics was reinforced by the absence of any other treatment and by histological findings including extensive mucosal necrosis without stenotic lesion and without mesenteric vessels alteration. The patient required emergency total colectomy and was discharged after 7 weeks of hospitalisation in the intensive care unit.

Acute Disease↗
PubMed1995

Differential targeting to the plasma membrane of the Torpedo 15-kDa proteolipid expressed in oocytes.

Xenopus laevis oocytes were injected with poly(A)+ RNAs extracted from the electric lobes of Torpedo marmorata, which contain a homogeneous population of cholinergic neurons. These primed oocytes were able to synthesize acetylcholine and to release the neurotransmitter in a calcium-dependent manner. Fractionation of oocyte membranes as well as immunofluorescence experiments showed that the 15-kDa proteolipid, a common subunit of the vacuolar H(+)-ATPase and of a presynaptic membrane protein capable of calcium-dependent acetylcholine translocation called the mediatophore, was located at the oocyte plasma membrane. In contrast, oocytes injected with separate transcripts encoding the 15-kDa proteolipid and choline acetyltransferase were unable to release acetylcholine in spite of an equivalent acetylcholine content and a higher level of 15-kDa proteolipid expression. We observed by immunofluorescence that under these conditions, the 15-kDa proteolipid was expressed in granular cytoplasmic membranes, which were then identified as being Golgi vesicles by cell fractionation. The striking difference in the distribution of the 15-kDa proteolipid expressed in oocytes primed with Torpedo electric lobe mRNA as compared with that seen in oocytes injected with the cRNA alone suggests that another protein endogenous to the electric lobe may be implicated in the localization of the 15-kDa proteolipid at the plasma membrane. Moreover, such a targeting mechanism could contribute to the capacity of electric lobe mRNA-injected oocytes to release acetylcholine.

Acetylcholine↗
PubMed1994

In vitro expression of the 15 kDa subunit of the mediatophore and functional reconstitution of acetylcholine release.

The mediatophore is a presynaptic oligomeric protein purified from the presynaptic plasma membrane of Torpedo synaptosomes on the basis of its ability to mediate a calcium-dependent acetylcholine release when solubilized and reconstituted into proteoliposomes. We investigated the ACh translocating activity of the 15 kDa proteolipid subunit of the mediatophore when expressed in Xenopus oocytes and reconstituted into proteoliposomes loaded with ACh. 1. A calcium-dependent ACh translocation was observed when oocytes were injected with polyadenylated mRNAs extracted from the electric lobe of the Torpedo brain or with an in vitro transcribed RNA encoding the 15 kDa subunit. 2. No release response was obtained when oocytes were non-injected or injected with Torpedo liver mRNAs. 3. This ACh translocation mechanism showed calcium-dependent activation and desensitisation and was inhibited by cetiedil, sharing these properties with the release of ACh observed at the synapse. 4. The ACh translocating activity of an N terminal deleted mediatophore 15 kDa subunit was strongly reduced and the deleted proteolipid appeared less sensitive to the action of cetiedil (alpha-cyclohexyl-alpha-(3-thienyl)-acetate of perhydroazepinyl-alpha-ethyl citrate monohydrate). 5. A significant ACh release response was observed when the 15 kDa proteolipid of the H(+)-ATPase from bovine chromaffin granules was tested. 6. These results show that this ACh translocating activity could be induced in the oocyte membranes by the expression of the 15 kDa subunit alone.

Acetylcholine↗
PubMed1994

Stimulation by recombinant human growth hormone of growth and development of remaining bowel after subtotal ileojejunectomy in rats.

The impact of human recombinant growth hormone (GH) after massive small bowel resection was studied in 38 weaning female Wistar rats (65 +/- 5 days old; 193 +/- 26 g). Animals underwent a 80% small bowel resection, leaving in place similar lengths of jejunum and ileum. Animals were assigned to four groups: group A (n = 9), small bowel resection only; group B (n = 10), resection and treatment with 0.2 GH units (GHU) s.c. every other day; group C (n = 9), resection and 0.4 GHU; and group D (n = 10), laparotomy without intestinal resection. Twenty-eight days later, weight gain (percentage of initial weight) was 1 +/- 3 in group A, 12 +/- 8 in group B, 12 +/- 9 in group C, and 16 +/- 7 in group D; p < 0.001, groups B-D. Time to recover initial weight was 26.2 +/- 3.3 days in group A; 11.7 +/- 5.4 days in group B (p < 0.001); and 16 +/- 6.1 days in group C (p < 0.001 vs. A). The size of the intestinal remnant after the rats were killed was 1.3 +/- 0.6 cm (13 +/- 10% of initial length) in A; 5.15 +/- 2.4 cm (37 +/- 18%) in B (p < 0.01); 4.2 +/- 2.3 cm (33 +/- 20%) in C (p < 0.01 vs. A); and 4.4 +/- 3.5 cm (5.8 +/- 4.9%) in D (p < 0.001 vs A). Villus height and diameter, average number of mitosis per field, and muscular layer and wall thickness were greater in groups A, B, and C than in group D (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

A precise investigation on the TL behavior of LiF: Mg, Cu, P (GR-200A).

LiF: Mg, Cu, P is a TL material presenting unique dosimetric features. The TL sensitivity of this material was studied as a function of the annealing temperature and of the repeated cycles of annealing-irradiation-readout. A fading study was carried out over a period of 40 days with the purpose of checking the stability of the stored dosimetric information as a function of different annealing temperatures. A detailed statistical analysis of sets of data, obtained from repeated measurements on a group of ten dosimeters, is presented.

Fluorides↗
PubMed1993

Antisense probes against mediatophore block transmitter release in oocytes primed with neuronal mRNAs.

Antisense oligodesoxynucleotides were used to determine whether the mediatophore proteolipid is necessary for the Ca(2+)-dependent release of the neurotransmitter acetylcholine. Xenopus laevis oocytes were injected with poly(A)+ mRNAs extracted from the electric lobes of Torpedo marmorata. The electric lobes contain an homogeneous population of cholinergic neurons homologous to motoneurons. Addition of antisense probes hybridizing to the mediatophore 15 kDa subunit inhibited the expression of both the mediatophore proteolipid in oocyte membranes and the Ca(2+)-dependent acetylcholine release. Expression of other neuronal functions such as synthesis of [14C]acetylcholine from [14C]acetate was not inhibited. Another antisense probe specific for the sequence of a related proteolipid cDNA (the 15 kDa subunit of the chromaffin granule protonophore) was used as a control. It did not hybridize with the Torpedo mediatophore mRNA and, injected in addition to electric lobe mRNAs, it did not inhibit either mediatophore expression or acetylcholine release. We showed in addition that the mRNA primed oocytes did not contain a vesicular pool of acetylcholine. It was concluded (i) that the mediatophore proteolipid is essential for Ca(2+)-dependent acetylcholine release and (ii) that the cytosolic pool of neurotransmitter seems to be preferentially used in this system.

Acetylcholine↗
PubMed1993

Retroviral-mediated gene transfer of the porcine choline acetyltransferase: a model to study the synthesis and secretion of acetylcholine in mammalian cells.

We have constructed a recombinant retrovirus that expresses choline acetyltransferase (ChAT) by placing the porcine enzyme cDNA under the control of the 5' long terminal repeat of the retroviral vector pMMuLV. Using retrovirus-mediated gene transfer, we have expressed ChAT in astroglial (STR-SVLT) and neuroendocrine (RIN) cell lines. Both genetically modified cell types synthesize acetylcholine (ACh). ACh is also present in the culture medium at a low concentration relative to that found in the modified cells. This result suggests that the synthesized ACh is retained within the cells and released by these two cell types. Release of ACh is not increased in the presence of the calcium ionophore A23187 or by depolarizing concentrations of potassium in either STR-SVLT or in RIN cells. The implications of these studies for understanding ACh release mechanisms are discussed.

Acetylcholine↗
PubMed1992

Exercise is not associated with better diabetes control in type 1 and type 2 diabetic subjects.

In the clinical setting, the impact of educational efforts on the amount of regular exercise and its effects on diabetes control are unclear. Fifty type 1 diabetic, 50 type 2 diabetic and 70 non-diabetic subjects were evaluated using a questionnaire for type, duration and intensity of exercise to assess weekly energy expenditure. Diabetic subjects did not exercise more than controls: 36% of the type 1, 46% of the type 2 and 46% of the control subjects admitted no physical activity, and those exercising regularly had similar energy expenditure: 1808 +/- 320, 2722 +/- 617, 2523 +/- 304 (mean +/- SEM) kcal/week respectively (P = NS). There was no correlation between the degree of activity and HbA1c levels, or hypoglycaemic events. HbA1c levels were less than 6,8% in 31% of nonactive patients versus 21% of active patients (P = NS). A negative correlation was found between physical activity and daily insulin usage (r = 0.27, P less than 0.05), but differences between patients averaged only 4IU/1000 kcal energy expenditure/day. We conclude that patients' attitude towards exercise was not improved by our educational methods and that physical exercise was not necessarily associated with good blood glucose control.

Body Mass Index↗