Biomedical subjects

C Delporte

Publications and source records attributed to C Delporte.

At least 19 recordsLinked to original sources

PubMed2006

Role of endogenous ghrelin in the hyperphagia of mice with streptozotocin-induced diabetes.

Ghrelin is an orexigenic peptide involved in the regulation of energy homeostasis. To investigate the role of ghrelin in the hyperphagia associated with uncontrolled streptozotocin-induced diabetes, food intake was followed in diabetic ghrelin knockout (ghrelin(-/-)) and control wild-type (ghrelin(+/+)) mice and diabetic Naval Medical Research Institute noninbred Swiss mice treated with either saline or the ghrelin receptor antagonist, D-Lys3-GH-releasing peptide-6 (D-Lys3-GHRP-6) for 5 d. In diabetic ghrelin(-/-) mice, hyperphagia was attenuated, and the maximal increase in food intake was 50% lower in mutant than in wild-type mice. The increased food intake observed during the light period (1000-1200 h) in ghrelin(+/+) mice was abolished in mutant mice. Diabetic ghrelin(-/-) mice lost 12.4% more body weight than ghrelin(+/+) mice. In diabetic ghrelin(+/+) mice, but not in ghrelin(-/-) mice, the number of neuropeptide Y (NPY)-immunoreactive neurons was significantly increased. Diabetic Naval Medical Research Institute noninbred Swiss mice were hyperphagic and had increased plasma ghrelin levels. Treatment with D-Lys3-GHRP-6 reduced daily food intake by 23% and reversed the increased food intake observed during the light period. The change in the number of NPY- (2.4-fold increase) and alpha-MSH (1.7-fold decrease)-immunoreactive hypothalamic neurons induced by diabetes was normalized by D-Lys3-GHRP-6 treatment. Our results suggest that enhanced NPY and reduced alpha-MSH expression are secondary to the release of ghrelin, which should be considered the underlying trigger of hyperphagia associated with uncontrolled diabetes.

Animals↗

PubMed2005

Influence of ghrelin on interdigestive gastrointestinal motility in humans.

BACKGROUND: Recent studies in animals have shown that ghrelin stimulates upper gastrointestinal motility through the vagus and enteric nervous system. The aim of the present study therefore was to simultaneously investigate the effect of administration of ghrelin on upper gastrointestinal motility and to elucidate its mode of action by measuring plasma levels of gastrointestinal hormones in humans. MATERIALS AND METHODS: Nine healthy volunteers (four males; aged 22-35 years) underwent combined antroduodenal manometry and proximal stomach barostat study on two separate occasions at least one week apart. Twenty minutes after the occurrence of phase III of the migrating motor complex (MMC), saline or ghrelin 40 mug was administered intravenously over 30 minutes in a double blind, randomised, crossover fashion. Ghrelin, motilin, pancreatic polypeptide, glucagon, and somatostatin were measured by radioimmunoassay in blood samples obtained at 15-30 minute intervals. The influence of ghrelin or saline on MMC phases, hormone levels, and intraballoon volume was compared using paired t test, ANOVA, and chi(2) testing. RESULTS: Spontaneous phase III occurred in all subjects, with a gastric origin in four. Administration of ghrelin induced a premature phase III (12 (3) minutes, p<0.001; gastric origin in nine, p<0.05), compared with saline (95 (13) minutes, gastric origin in two). Intraballoon volumes before infusion were similar (135 (13) v 119 (13) ml; NS) but ghrelin induced a longlasting decrease in intraballoon volume (184 (31) v 126 (21) ml in the first 60 minutes; p<0.05). Administration of ghrelin increased plasma levels of pancreatic polypeptide and ghrelin but motilin, somatostatin, and glucagon levels were not altered. CONCLUSIONS: In humans, administration of ghrelin induces a premature gastric phase III of the MMC, which is not mediated through release of motilin. This is accompanied by prolonged increased tone of the proximal stomach.

Adult↗

PubMed2005

Protective effects of a standard extract of Mangifera indica L. (VIMANG) against mouse ear edemas and its inhibition of eicosanoid production in J774 murine macrophages.

A standard aqueous extract of Mangifera indica L., used in Cuba as antioxidant under the brand name VIMANG, was tested in vivo for its anti-inflammatory activity, using commonly accepted assays. The standard extract of M. indica, administered orally (50-200mg/kg body wt.), reduced ear edema induced by arachidonic acid (AA) and phorbol myristate acetate (PMA) in mice. In the PMA model, M. indica extract also reduced myeloperoxidase (MPO) activity. In vitro studies were performed using macrophage cell line J774 stimulated with pro-inflammatory stimuli lipopolysaccharide-interferon gamma (LPS-IFNgamma) or calcium ionophore A23187 to determine prostaglandin PGE(2) or leukotriene LTB(4) release, respectively. The extract inhibited the induction of PGE(2) and LTB(4) with IC(50) values of 21.7 and 26.0microg/ml, respectively. Mangiferin (a glucosylxanthone isolated from the extract) also inhibited these AA metabolites (PGE(2), IC(50) value=17.2microg/ml and LTB(4), IC(50) value=2.1microg/ml). These results represent an important contribution to the elucidation of the mechanism involved in the anti-inflammatory and anti-nociceptive effects reported for the standard extract of M. indica VIMANG.

Administration, Oral↗

PubMed2005

Analgesic-antiinflammatory properties of Proustia pyrifolia.

The antiinflammatory (per os and topic) and analgesic (per os) properties of the aerial part of Proustia pyrifolia a species in danger of extinction were investigated, and the major compounds of two of its active extracts were isolated. In addition, the evaluation of cytotoxicity in three tumoral cell lines and the acute toxicity of the crude methanol extract were also assayed, together with the antioxidant activity for the different extracts of this species. The results of the evaluation of the topic antiinflammatory activities induced by arachidonic acid, and phorbol 12-myristate 13-acetate of the different extracts showed that this species possesses active constituents that could diminish cyclo-oxygenase and lipoxygenases activities, the enzymes that allow the synthesis of proinflammatory endogenous substances as prostaglandin E(2) and leukotrienes, respectively. Our results corroborate the antiinflammatory and analgesic effects of Proustia pyrifolia, and could justify its use in folk medicine for the treatment of rheumatic and gout illnesses. From bio-active extracts beta-sitosterol, quercetin and dihydroquercetin were obtained, and these compounds could explain in part the antiinflammatory, analgesic and antioxidant activities of this species. The crude methanol extract did not present acute toxicity or cytotoxic activity, however only this extract exhibited antioxidant activity.

Analgesics↗

PubMed2004

A recombinant adenoviral vector encoding functional vasoactive intestinal peptide.

Vasoactive intestinal peptide (VIP) is a small neuropeptide, which exerts pleiotropic functions. Based on its immunomodulatory, secretory, and possibly trophic effects, VIP is a valuable candidate molecule for the management of autoimmune disease. The purpose of this study was to develop a recombinant viral vector capable of directing the expression of functional VIP. The vector rAd5CMVhVIP was constructed and used to infect 293 cells. VIP expression was measured by an ELISA and function was evaluated by measurement of intracellular cAMP formation. rAd5CMVhVIP directed VIP expression and the transgenic VIP elicited a dose-dependent increase of intracellular cAMP, mediated through the VIP receptor VPAC(1). This is the first report showing the construction of a recombinant viral vector encoding biologically active VIP.

Adenoviridae↗

PubMed2002

Bioactive phenolic derivatives from Acaena splendens methanol extract.

Acaena splendens H. et A. has been used in Chilean folk medicine for the treatment of fever and inflammation. A description of the in vivo reduction of bacterial pyrogen-induced fever in rabbits and carrageenan-induced paw oedema in guinea pigs is presented. The methanol extract named ME-1, obtained after succesive extractions with petroleum ether and dichloromethane, showed a strong antipyretic action (45.7% of effect), though the antiinflammatory activity was only observed after submitting this extract to column fractionation, giving a crude mixture of flavonoids named C4 with both activities (55.7% and 98.9% of antiinflammatory and antipyretic effect respectively at a dose of 600 mg/kg). The bioassay-guided fractionation by column chromatography afforded the active fraction, which contained (-,-)-epicatechin, tiliroside, 7-O-acetyl-3-O-beta-D-glucosyl-kaempferol and 7-beta-D-glucosyloxy-5-hydroxy-chromone.

Analgesics, Non-Narcotic↗

PubMed2001

Analgesic and anti-inflammatory effects of Mangifera indica L. extract (Vimang).

Vimang is an aqueous extract of Mangifera indica used in Cuba to improve the quality of life in patients suffering from elevated stress. To assess its possible analgesic and antiinflammatory effects, the results of a standard extract evaluation are presented. Analgesia was determined using acetic acid-induced abdominal constriction and formalin-induced licking. Antiinflammatory effects were evaluated using carrageenan- and formalin-induced oedema. Vimang (50-1000 mg/kg, p.o.) exhibited a potent and dose-dependent antinociceptive effect against acetic acid test in mice. The mean potency (DE(50)) was 54.5 mg/kg and the maximal inhibition attained was 94.4%. Vimang (20-1000 mg/kg, p.o.) dose-dependently inhibited the second phase of formalin-induced pain but not the first phase. The DE(50) of the second phase was 8.4 mg/kg and the maximal inhibition was 99.5%, being more potent than indomethacin at doses of 20 mg/kg. Vimang (20-1000 mg/kg, p.o.) significantly inhibited oedema formation (p < 0.01 or p < 0.05) of both carrageenan- and formalin-induced oedema in rat, guinea-pigs and mice (maximal inhibitions: 39.5, 45.0 and 48.6, respectively). The inhibitions were similar to those produced by indomethacin and sodium naproxen, p.o. The different polyphenols found in Vimang could account for the antinociceptive and antiinflammatory actions reported here for the first time for M. indica bark aqueous extract.

Acetic Acid↗

PubMed2001

Characterization of functional VIP/PACAP receptors in the human erythroleukemic HEL cell line.

The presence of VIP/PACAP receptors was investigated on the human erythroleukemic cell line HEL. Specific binding of [125I]-PACAP or [125I]-VIP on HEL cells or membranes was very low and did not allow to perform competition curves. At 37 degrees C PACAP transiently increased cAMP levels in the presence of the non-specific phosphodiesterase inhibitor IBMX, suggesting rapid desensitization. Kinetic studies revealed that optimal conditions to measure the EC(50) of PACAP(1-27) were 10 min at 20 degrees C. Under those conditions, PACAP-related peptides increased cAMP levels with EC(50) in agreement with the pharmacological profile of the VPAC(1) receptor subtype: PACAP = VIP > [K(15), R(16,) L(27)]VIP(1-7)/GRF(8-27) = [R(16)]ChSn (two VPAC(1) agonists) >> helodermin = secretin. RO 25-1553, a selective activator of VPAC(2) receptor was inactive at 1 microM. Dose-response curves of VPAC(1) agonist molecules (PACAP, VIP, [K(15), R(16), L(27)]VIP(1-7)/GRF(8-27), [R(16)]ChSn) were shifted to the right by the VPAC(1) receptor antagonist [AcHis(1), D-Phe(2), Lys(15), Leu(17)]VIP(3-7)/GRF(8-27), with a K(i) of 3 +/- 1 nM (n = 3). The presence of VPAC(1) receptor mRNA was confirmed by RT-PCR. Preincubation with PACAP or PMA showed that VPAC(1) receptors underwent homologous and heterologous desensitization. This study provides the first evidence for the expression of functional VPAC(1) receptors undergoing rapid desensitization in HEL cells.

Base Sequence↗

PubMed2001

Abnormal distribution of aquaporin-5 water channel protein in salivary glands from Sjögren's syndrome patients.

Patients with Sjögren's syndrome (SS) suffer from deficient secretion of saliva due to an autoimmune destruction of salivary glands, however, glandular dysfunction also occurs without destruction. Based upon its abnormal distribution in SS salivary glands, a potential role for the water channel protein aquaporin-5 (AQP5) is proposed in the pathogenesis of SS. The immunohistochemical distribution of AQP5 was compared in minor salivary gland biopsies obtained from women after informed consent: primary SS (53.2 +/- 14 years old, n = 10), healthy volunteers (46.2 +/- 17 years old, n = 10), patients with sarcoidosis (37 and 48 years old), and patients with non-specific sialoadenitis (54 and 61 years old). Biopsies from normal subjects revealed AQP5 primarily at the apical membrane of the salivary gland acinus. In contrast, biopsies from SS patients revealed AQP5 primarily at the basal membranes of the acinus. The AQP5 distribution in biopsies from patients with other dry mouth disorders, such as non-specific sialoadenitis or sarcoidosis, was similar to biopsies from control subjects. Computer-assisted microscopy was performed to quantitatively evaluate AQP5 distribution in the immunoreactive acini of both SS and control subjects. Biopsies from SS patients had higher labeling indices (percentage of acinus area immunoreactive for AQP5) at the basal membrane when compared with biopsies from control subjects. In contrast, biopsies of SS patients exhibited lower labeling indices at the apical membrane when compared with biopsies from control subjects. To verify the specificity of the AQP5 antibody, Western blot analysis was performed on membranes from Xenopus oocytes injected with AQP5 cRNA or on membranes from minor salivary glands of control subjects and SS patients. In each case, the immunoblots had a 27 kd band, corresponding to the expected molecular weight of AQP5. Abnormal distribution of AQP5 in salivary gland acini is likely to contribute to the deficiency of fluid secretion, which is a defining feature of Sjögren's syndrome.

Adult↗

PubMed2000

Characterization of a novel VPAC(1) selective agonist and identification of the receptor domains implicated in the carboxyl-terminal peptide recognition.

Vasoactive Intestinal Polypeptide (VIP) interacts with a high affinity to two subclasses of G protein coupled receptors named VPAC(1) and VPAC(2), and has a 3 - 10 fold preference for VPAC(1) over VPAC(2) receptors. Selective ligands for each receptor subclass were recently described. [R(16)]-PACAP (1 - 23) and [L(22)]-VIP are two selective VPAC(1) agonists. Chimaeric human VPAC(2)-VPAC(1) recombinant receptors expressed in CHO cells were used to identify the receptor domains implicated in these two selective ligands recognition. The VPAC(2) preference for [R(16)]-PACAP (1 - 27) over [R(16)]-PACAP (1 - 23) did not require the receptor's NH(2)-terminus domain but involved the whole transmembrane domain. In contrast, the selectivity of [L(22)]-VIP depended only on the presence of the NH(2) terminus and EC(2) domains of the VPAC(1) receptor. The present data support the idea that in the GPCR-B family of receptors the different selective ligands require different domains for their selectivity, and that the peptides carboxyl terminal sequence (amino acids 24 - 27) folds back on the transmembrane receptor domain, close to the peptides, aminoterminus.

Amino Acid Sequence↗

PubMed1999

Re-engineering the functions of a terminally differentiated epithelial cell in vivo.

Because of their easy access, and important role in oral homeostasis, mammalian salivary glands provide a unique site for addressing key issues and problems in tissue engineering. This manuscript reviews studies by us in three major directions involving re-engineering functions of salivary epithelial cells. Using adenoviral-mediated gene transfer in vivo, we show approaches to i) repair damaged, hypofunctional glands and ii) redesign secretory functions to include endocrine as well as exocrine pathways. The third series of studies show our general approach to develop an artificial salivary gland for clinical situations in which all glandular tissue has been lost.

Animals↗

PubMed1999

Human A-type ANP receptor upregulation by PACAP and carbachol in neuroblastoma cells.

Pituitary adenylyl cyclase activating polypeptide (PACAP-27), forskoline and carbachol increased type A atrial natriuretic peptide receptor (NPR-A) density, as well as NPR-A mRNA level, in the human neuroblastoma NB-OK-1 cell line. TPA did not have any effect per se, but blunted the effect of PACAP-27 on both NPR-A density and NPR-A mRNA. The half-life of the NPR-A mRNA was not modified by any of the agents tested. Our data support an original transcriptional upregulation of human NPR-A in response to cAMP-induced agents, and in response to carbachol.

Animals↗

PubMed1999

Cloning of Trp1beta isoform from rat brain: immunodetection and localization of the endogenous Trp1 protein.

The Trp gene product has been proposed as a candidate protein for the store-operated Ca2+ channel, but the Trp protein(s) has not been identified in any nonexcitable cell. We report here the cloning of a rat brain Trp1beta cDNA and detection and immunolocalization of the endogenous and expressed Trp1 protein. A 400-bp product, with >95% homology to mouse Trp1, was amplified from rat submandibular gland RNA. Rat-specific primers were used for cloning of a full-length rat brain Trp1beta cDNA (rTrp1), encoding a protein of 759 amino acids. Northern blot analysis demonstrated the transcript in several rat and mouse tissues. The peptide (amino acids 523-536) was used to generate a polyclonal antiserum. The affinity-purified antibody 1) immunoprecipitated human Trp1 (hTrp1) from transfected HEK-293 cells, 2) reacted with a protein of approximately 92 kDa, but not with hTrp3, in membranes of hTrp3-expressing HEK-293 cells, and 3) reacted with proteins of 92 and 56 kDa in human and rat brain membranes. Confocal microscopy and cell fractionation demonstrated that endogenous and expressed hTrp1 and expressed hTrp3 proteins were localized in the plasma membrane of HEK-293 cells, consistent with their proposed role in Ca2+ influx. The data demonstrate for the first time the presence of Trp1 protein in a nonexcitable cell.

Amino Acid Sequence↗

PubMed1999

Natriuretic peptide receptors of type A in human neuroblastomas.

Functional natriuretic peptide receptors of type A (NPR-A) were detected in the human neuroblastoma NB-OK-1, SK-N-SH and SK-N-BE, but not the SH-SY5Y, cell lines. Also, NPR-A mRNA was detected in 19 of the 25 tumor neuroblastoma samples tested in this study. Five of the eight tumor neuroblastoma samples that were assayed for atrial natriuretic peptide (ANP) binding revealed the presence of ANP-binding sites. In the human neuroblastoma NB-OK-1 cell line, [(3)H] thymidine incorporation was increased in response to ANP, decreased in response to pituitary adenylate cyclase-activating polypeptide (PACAP-27), and the stimulatory effect of ANP was inhibited by PACAP-27. Tissue transglutaminase activity was decreased by ANP and PACAP-27, and their effects were additive. However, neither cell cycle phases, cell growth, or cell apoptosis were modified by ANP or PACAP-27 treatments.

Apoptosis↗

PubMed1998

Relationship between adenovirus-mediated aquaporin 1 expression and fluid movement across epithelial cells.

AdhAQP1, a recombinant adenovirus encoding the human water channel aquaporin 1 (AQP1), has been shown to be useful for gene therapy of salivary glands rendered hypofunctional following irradiation. Here we utilized AdhAQP1 to examine the relationship between AQP1 expression and fluid movement across a polarized salivary epithelial cell monolayer. In response to a 440 to 340 mosm gradient, net fluid movement across cells infected with AdhAQP1 was approximately 10-fold that seen in uninfected cells or cells infected with a control virus. At a multiplicity of infection (MOI) of 5, fluid movement was linear for 15-30 min. Increasing the osmotic gradient resulted in a proportional increase in fluid movement. At low virus MOIs (0.1-1.0), fluid movement was markedly enhanced relative to that seen at higher MOIs (approximately 5.10), where the level of AQP1 expression and number of cells transduced were considerably greater. We conclude that significant, osmotically-obliged fluid movement in a salivary cell monolayer with low basal water permeability does not require high levels of AQP1 expression.

Adenoviridae↗

PubMed1998

A polarized salivary cell monolayer useful for studying transepithelial fluid movement in vitro.

There are no reported, convenient in vitro models for studying polarized functions in salivary epithelial cells. Accordingly, we examined three often-used salivary cell lines for their ability to form a polarized monolayer on permeable, collagen-coated polycarbonate filters. Only the SMIE line, derived from rat submandibular gland, had this ability. The SMIE cell monolayer exhibited junctional complexes, with a tight-junction-associated protein, ZO-1, localized to cell-cell contact areas. The Na+/K+-ATPase alpha1-subunit was detected predominantly in the basolateral membranes, while the Na+/H+ exchanger isoform 2 appeared primarily in the apical membranes. Using adenovirus-mediated cDNA transfer, SMIE cells were shown to be capable of routing marker proteins (beta-galactosidase +/- a nuclear targeting signal, alpha1-antitrypsin, aquaporin-1) to appropriate locations. Furthermore, this salivary cell monolayer provided a convenient tool for studying aquaporin-1-mediated, osmotically directed, transepithelial fluid movement in vitro. Thus, SMIE cells appear to be a useful experimental model with which to study some polarized functions in a salivary epithelial cell line.

Adenoviridae↗

PubMed1998

Molecular cloning and in vitro properties of the recombinant rabbit secretin receptor.

The rabbit secretion receptor cDNA was cloned from rabbit pancreas using combined polymerase chain reaction (PCR)/rapid amplification of cDNA ends (PCR/RACE) approaches. The rabbit cDNA encoded 445 amino acids and had 80 and 85% homology with rat- and human receptor, respectively, in terms of nucleic and amino acid sequences. Several regions where the rabbit receptor sequence diverged from the rat/human receptor sequences were observed in the putative extracellular domains of the receptor. A cDNA coding for a similar sequence with a 76 bp deletion after the 5th transmembrane domain was also found; it probably encoded an inactive protein. The whole rabbit secretin receptor cDNA was subcloned in expression vector pCR3.1, then stably and transiently transfected in Chinese hamster ovary (CHO) cells. The pharmacological properties of the rat and rabbit secretin receptor studies were compared by radiolabeled secretin binding, binding inhibition, and adenylate cyclase activation (using secretin analogs and fragments). Porcine secretin was equipotent with rabbit secretin on the rabbit secretin receptor, but fivefold more potent than rabbit secretin on the rat receptor. This was due to the serine-->arginine residue replacement, in position 16 of rabbit secretin. Amino terminal modified secretin analogs (secretin (2-27), [E3]secretin, [N3]secretin) and VIP were less potent than secretin on both secretin receptors, but more potent on the rabbit than on the rat receptor. The carboxy-terminally truncated fragment (1-26) had the same reduced potency on rat and rabbit receptors. Thus, the rabbit secretin receptor had original properties, different from those of the rat receptor.

Adenylyl Cyclases↗

PubMed1998

Safety of salivary gland-administered replication-deficient recombinant adenovirus in rats.

We have examined the safety of a replication-deficient recombinant adenovirus administered at a single, high dose intraductally to rat submandibular glands or systemically via the femoral vein. The virus used directed the synthesis of human aquaporin-1, a water channel protein, and is termed AdhAQP1. Comparisons were made 1 and 9 days post-infection with animals administered either a similar virus encoding no transgene or the viral suspension buffer. Animals were specifically not given anti-inflammatory drugs to impede the well-known immunopathologic response to recombinant adenoviral administration. Serum chemistries and hematological parameters were monitored. Rats were subjected to complete gross necropsy and selected tissues were evaluated by histopathology. Most clinical chemistry and hematology values were within normal ranges; however, evidence of inflammation (e.g., elevated lactic dehydrogenase, total leukocyte count) was seen. Gross pathology was normal, as was histopathology, excepting rare focal areas of necrosis. The results show that intrasalivary gland or intravenous AdhAQP1 administration leads to low levels of toxicity in rats.

Adenoviridae↗