Biomedical subjects

A Villeneuve

Publications and source records attributed to A Villeneuve.

At least 19 recordsLinked to original sources

PubMed2001

Failure of dogs to shed oocysts after being fed bovine fetuses naturally infected by Neospora caninum.

Neospora caninum is a protozoan that causes abortion in cattle. The dog has recently been identified as a definitive host for N. caninum. To verify if bovine fetuses can infect dogs, nine 2-4-month-old dogs were fed bovine fetuses naturally infected by N. caninum. None of the dogs excreted oocysts, seroconverted, had clinical signs or lesions compatible with N. caninum infection. Additional studies will be necessary to determine the natural mode of infection of dogs by N. caninum.

Animals↗

PubMed2001

Prostaglandin E(2) increases cyclic AMP and inhibits endothelin-1 production/secretion by guinea-pig tracheal epithelial cells through EP(4) receptors.

Prostaglandin E(2) (PGE(2)) increased adenosine 3' : 5'-cyclic monophosphate (cyclic AMP) formation in tracheal epithelial cells and concomitantly decreased the production/secretion of immunoreactive endothelin (irET). Naturally occurring prostanoids and selective and non-selective EP receptor agonists showed the following rank order of potency in stimulating cyclic AMP generation by epithelial cells: PGE(2) (EP-selective)>16,16-dimethyl PGE(2) (EP-selective)>11-deoxy PGE(2) (EP-selective)>>>iloprost (IP/EP(1)/EP(3)-selective), butaprost (EP(2)-selective), PGD(2) (DP-selective), PGF(2alpha) (FP-selective). The lack of responsiveness of the latter prostanoids indicated that the prostanoid receptor present in these cells is not of the DP, FP, IP, EP(1), EP(2) or EP(3) subtype. Pre-incubating the cells with the selective TP/EP(4)-receptor antagonists AH23848B and AH22921X antagonized the PGE(2)-evoked cyclic AMP generation. This suggested that EP(4) receptors mediate PGE(2) effects. However, in addition to any antagonistic effects at EP(4)-receptors, both compounds, to a different extent, modified cyclic AMP metabolism. The selective EP(1), DP and EP(2) receptor antagonist (AH6809) failed to inhibit PGE(2)-evoked cyclic AMP generation which confirmed that the EP(2) receptor subtype did not contribute to the change in cyclic AMP formation in these cells. The PGE(2)-induced inhibition of irET production by guinea-pig tracheal epithelial cells was due to cyclic AMP generation and activation of the cyclic AMP-dependent protein kinase since this effect was reverted by the cyclic AMP antagonist Rp-cAMPS. These results provide the first evidence supporting the existence of a functional prostaglandin E(2) receptor that shares the pharmacological features of the EP(4)-receptor subtype in guinea-pig tracheal epithelial cells. These receptors modulate cyclic AMP formation as well as ET-1 production/secretion in these cells.

Adenosine↗

PubMed2001

Evaluation of a strategic deworming program in dairy heifers in Quebec based on the use of moxidectin, an endectocide with a long persistency.

Two different deworming strategies based on the use of moxidectin, a broad spectrum endectocide with persistency against Ostertagia ostertagi, were evaluated in grazing dairy heifers. Eighty-four heifers unexposed to parasitic infection were randomly allocated to 3 different groups: untreated (Group 1), treated at 3 and 10 weeks after turnout with 0.5 mg/kg/body weight (BW) of topical moxidectin (Group 2), or treated at turnout and 10 weeks later with 0.5 mg/kg/BW of topical moxidectin (Group 3). The heifers were turned out on June 6 (Day 0) to a naturally contaminated pasture divided into 3 sections by an electrical fence. Each group of heifers was put on a different section of pasture. The trial ended when they were housed on October 29 (Day 143). The results of this experiment confirmed the beneficial effect of 2 strategic treatments with moxidectin pour-on under field conditions in Quebec. The parasitological parameters showed a statistical difference in terms of mean fecal egg counts between treated and control groups (ANOVA, P < or = 0.006). After turnout, pasture larval counts were consistently higher for Group 1 compared with counts for Group 2 or 3. All heifer groups gained weight during the trial period, but the weight gain profile of both treated groups was significantly higher than that of the untreated controls (ANOVA, P < 0.03). During the trial period, Group 2 and Group 3 gained 77.7 kg BW and 73.2 kg BW, respectively, while Group 1 gained only 57.9 kg BW, despite the fact that heifers of Group 1 received a greater quantity of supplementary feed while on pasture.

Abomasum↗

PubMed2000

Optical field-induced mass transport in As2S3 chalcogenide glasses.

We report the observation of a photorefractivelike nonlinearity responsible for the formation of giant relief modulations in amorphous semiconductor glasses. The photoinduced softening of the matrix, formation of defects with enhanced polarizability, and their drift under the optical field gradient force is believed to be the origin of the mass transport.

Journal Article↗

PubMed2000

Adenosine induces cyclic-AMP formation and inhibits endothelin-1 production/secretion in guinea-pig tracheal epithelial cells through A(2B) adenosine receptors.

1. The adenosine receptor subtype mediating adenosine 3' : 5'-cyclic monophosphate (cyclic AMP) formation and the effect of its activation on endothelin-1 (ET-1) secretion were studied in primary cultures of tracheal epithelial cells. 2. Adenosine analogues showed the following rank order of potency (pD(2) value) and intrinsic activity on the generation of cyclic AMP by tracheal epithelial cells: 5'-N-ethylcarboxyamidoadenosine (NECA, A(1)/A(2A)/A(2B), pD(2): 5.44+/-0.16)>adenosine (ADO, non selective, pD(2): 4.99+/-0. 09; 71+/-9% of NECA response) >/=2-Cl-adenosine (2CADO, non selective, pD(2): 4.72+/-0.14; 65+/-9% of NECA response)>>>CGS21680 (A(2A); inactive at up to 100 microM). 3. Cyclic AMP formation stimulated by NECA in guinea-pig tracheal epithelial cells was inhibited by adenosine receptor antagonist with the following order of apparent affinity (pA(2) value): Xanthine amine congeners (XAC, A(2A)/A(2B), 7.89+/-0.22)>CGS15943 (A(2A)/A(2B), 7.24+/-0. 26)>ZM241385 (A(2A), 6.69+/-0.14)>DPCPX (A(1), 6.51+/-0. 14)>3n-propylxanthine (weak A(2B), 4.30+/-0.10). This rank order of potency is typical for A(2B)-adenosine receptor. 4. Adenosine decreased basal and LPS-stimulated irET production in a concentration-dependent manner. Moreover, NECA but not CGS21680 inhibited LPS-induced irET production. 5. The inhibitory effect of NECA on LPS-induced irET production was reversed by XAC (pA(2)=8.84+/-0. 12) and DPCPX (pA(2)=8.10+/-0.22). 6. These results suggested that adenosine increased cyclic AMP formation and inhibited irET production/secretion by guinea-pig tracheal epithelial cells through the activation of a functional adenosine receptor that is most likely the A(2B) subtype. This adenosine receptor may be involved in the regulation of the level of ET-1 production/secretion by guinea-pig tracheal epithelial cells in physiological as well as in pathophysiological conditions.

Adenosine↗

PubMed2000

Vertical and horizontal transmission of Neospora caninum in dairy herds in Québec.

Neospora caninum is an important cause of abortion in dairy cattle. The objective of this observational study was to estimate the rate of vertical transmission of N. caninum in dairy herds in Québec and to investigate horizontal transmission in the same herds. The genealogy of cows from 23 dairy herds were examined. Prevalence of seropositive animals in herds studied varied from 4.3% to 61.8% (average, 21.9%). The overall rate of vertical transmission was estimated to be 44.4%, varying from 0% to 85.7%. Seven cases of horizontal transmission were identified in 6 of the 23 herds studied. Estimated vertical transmission rate varied from herd to herd, but appeared to be higher in herds with a high prevalence of seropositive animals. Although horizontal transmission was identified in 6 herds, it does not appear to be the major route of infection for N. caninum.

Animal Husbandry↗

PubMed2000

Glucocorticoids decrease endothelin-A- and -B-receptor expression in the kidney.

Glucocorticoids play an important role in circulatory homeostasis and in excess they cause hypertension. These corticosteroids affect the expression of many genes involved in blood pressure control including preproendothelin-1 (PPET-1), the precursor of endothelin-1 (ET-1), a potent vasoactive peptide. We have previously shown that glucocorticoids increase PPET-1 mRNA levels in rat aorta. Moreover, they also affect ET(A)- and ET(B)-receptor expression in various in vitro and in vivo situations. Both ET-1 and glucocorticoids exert direct effects in the kidney and are involved in vascular resistance and sodium balance. We therefore sought to determine the effects of glucocorticoids on renal PPET-1, ET(A)- and ET(B)-receptor expression in an animal model of glucocorticoid-induced hypertension. Wistar rats were given 2.5 mg/l of dexamethasone, a glucocorticoid agonist, in their drinking water for 1 or 5 days. Our data reveal that dexamethasone administration increases systolic blood pressure (SBP) in rats. SBP rose from 120 +/- 3 to 139 +/- 4 and 150 +/- 5 mmHg after 1 and 5 days treatments, respectively (p < 0.05). Furthermore, dexamethasone administration decreased ET(A) and ET(B)-receptor expression in the rat kidney. This effect was observed after 1 day of dexamethasone treatment with ET(A) and ET(B)-receptor mRNA levels decreasing to 83 +/- 2% and 80 +/- 5% of control values. respectively (p < 0.01). Both ET(A)- and ET(B)-receptor mRNA levels further declined to 67 +/- 3 and 65 +/- 6% of control values after 5 days of dexamethasone treatment, respectively (p < 0.001). Interestingly, kidney PPET-1 expression was not affected by dexamethasone administration. Our results suggest a contribution of renal ET receptors in glucocorticoid actions on blood pressure control.

Animals↗

PubMed1999

Genome-wide search for linkage of bipolar affective disorders in a very large pedigree derived from a homogeneous population in quebec points to a locus of major effect on chromosome 12q23-q24.

We completed a genome-wide scan for susceptibility loci for bipolar affective disorders in families derived from a rather homogeneous population in the Province of Québec. The genetic homogeneity of this population stems from the migration of founding families into this relatively isolated area of Québec in the 1830s. A possible founder effect, combined with a prevalence of very large families, makes this population ideal for linkage studies. Genealogies for probands can be readily constructed from a population database of acts of baptism and marriage from the early 1830s up to the present time (the BALSAC register). We chose probands with a DSM III diagnosis of bipolar affective disorder and who may be grouped within large families having genealogical origins with the founding population of the Saguenay-Lac-St-Jean area. Living members (n approximately 120) of a very large pedigree were interviewed using the Structured Clinical Interview for DSM III (SCID I), SCID II, and with a family history questionnaire. A diagnostic panel evaluated multisource information (interview, medical records, family history) and pronounced best-estimate consensus diagnoses on all family members. Linkage, SimAPM, SimIBD, and sib-pair analyses have been performed with 332 microsatellite probes covering the entire genome at an average spacing of 11 cM. GENEHUNTER and haplotype analyses were performed on regions of interest. Analysis of a second large pedigree in the same regions of interest permitted confirmation of presumed linkages found in the region of chromosome 12q23-q24.

Bipolar Disorder↗

PubMed1999

Nonevaluative social support reduces cardiovascular reactivity in young women during acutely stressful performance situations.

We tested whether the presence of a stranger reduces cardiovascular responses during stressful tasks if the evaluation potential of the stranger is minimized and whether cardiovascular responses are affected by the quality of support in a friendship. Undergraduate women performed stressful tasks in one of three conditions: Alone, with a same-sex Stranger, or with a same-sex best Friend. The stranger and friend could not hear participants' responses. Alone women had the greatest increases in SBP and HR while women in the Stranger and Friend conditions did not differ in their responses. In the Friend condition, HR responses were smallest in women who were highly satisfied with the support that they generally received from their friend. We conclude that the presence of a nonevaluative friend or stranger can reduce cardiovascular responses and that the quality of supportive ties modulates the impact of those ties on responses to stress.

Adolescent↗

PubMed1999

Respiratory nematodiases in raptors in Quebec.

This is a retrospective study on wild raptors submitted to the Université de Montréal (Quebec, Canada) from 1989 to 1996. Cyathostoma spp. (Nematoda: Syngamidae) adults and/or eggs were found in air sacs, lungs, bronchi, and trachea of 12 raptors (Falconiformes and Strigiformes) from Quebec, Canada, belonging to eight different species, five of which are first host records for this parasite: barred owl (Strix varia), snowy owl (Nyctea scandiaca), northern harrier (Circus cyaneus), northern goshawk (Accipiter gentilis), and broad-winged hawk (Buteo platypterus). The infection was considered fatal in four birds, while no significant clinical signs were observed in the other cases. Major pathologic changes included diffuse pyogranulomatous air sacculitis, pneumonia, and bronchitis. A few unidentified larval nematodes embedded in a granuloma were found in the lungs of an additional Coopers' hawk (Accipiter cooperii); they were not considered clinically significant. A dead nematode, surrounded by necrotic inflammatory cells, was found in the air sac of a northern goshawk. The presence of nematodes in air sacs or lungs should be considered in wild raptors demonstrating respiratory problems.

Air Sacs↗

PubMed1997

Evaluation of the protective efficacy of doramectin against sucking lice of cattle.

The protective efficacy of doramectin against sucking lice was evaluated under natural challenge conditions in Canada. Two studies with a similar experimental design were conducted in sequence. In each study, two groups of louse-free cattle received either doramectin at a dose of 200 micrograms/kg by subcutaneous injection or no treatment and were then mixed with louse-infested animals for the winter housing period. All animals were examined for lice on treatment day and thereafter at weekly intervals for 13 weeks. In the preliminary study, acquisition of infestation in the face of a very mild challenge of Linognathus vituli was delayed by a mean period of 49 days in doramectin-treated animals compared with untreated controls. The difference in the delay between the groups was significant (P < or = 0.04). In the second study, test animals experienced a moderate challenge of a mixed infestation of L. vituli and Solenopotes capillatus. Acquisition of infestation was delayed by a mean period of 25.6 days in doramectin-treated animals compared with controls, the difference between the two groups being highly significant (P < or = 0.0001). These studies confirmed the protective efficacy of doramectin against sucking lice under natural challenge conditions showing that infestation is prevented for a period of about 4 weeks following administration of the drug at its recommended dose.

Animals↗

PubMed1994

Determination of neutralizing epitopes in variable domains I and IV of the major outer-membrane protein from Chlamydia trachomatis serovar K.

Chlamydia trachomatis is a leading cause of sexually transmitted diseases and a number of strategies have been developed to produce vaccines to prevent its transmission. The purpose of this study was to map the neutralizing epitopes of C. trachomatis major outer-membrane protein (MOMP) serovar K by using anti-MOMP antibodies and synthetic peptides. Seven anti-MOMP monoclonal antibodies and three polyclonal antisera were produced and characterized. Their fine specificity was defined by direct binding assay on 15 peptides of 10 amino acid residues, overlapping by five residues, corresponding to the four variable domains (VDI-VDIV: residues 64-85, 139-160, 224-237 and 287-319) of MOMP serovar K. Our data confirmed that a neutralizing epitope is found in VDIV, defined by peptides K12 and K13. This epitope is 296TTLNPTIAG304, which has never been reported as a neutralizing epitope of serovar K. Another neutralizing epitope, defined by peptide K2, has been identified in VDI. This epitope is in the same position as 71VAGLEK76, a peptide with neutralizing activity found in serovar A, but they are not identical because antibodies against peptide K2 do not bind to this epitope. No neutralizing epitope was found in the two other variable domains (VDII and III). In summary, two neutralizing sites, one in variable domain I and one in variable domain IV, were identified in serovar K.

Amino Acid Sequence↗

PubMed1994

Mimicry of a neutralizing epitope of the major outer membrane protein of Chlamydia trachomatis by anti-idiotypic antibodies.

The major outer membrane protein (MOMP) is a primary target antigen for the development of chlamydial vaccine. This protein is composed of four variable domains (I to IV) flanked by constant regions. Some of the variable domains contain antigenic determinants that elicit a neutralizing antibody response. Murine monoclonal antibodies (MAbs) against three nonoverlapping epitopes of MOMP were developed. One of these, called DP10, bound to all serovars, as shown by immunoblot analysis, and neutralized chlamydial infectivity for hamster kidney (HaK) cells in a complement-independent in vitro assay. Furthermore, analysis of the fine specificity of this MAb showed that it recognized a synthetic peptide contained within variable domain IV of the MOMP. Anti-idiotypic antibodies (aId) directed against this anti-MOMP MAb were produced in rabbits. These aId specifically bound to the relevant idiotype (DP10) and inhibited the binding of anti-MOMP MAb (DP10) to MOMP preparations in a dose-dependent fashion. The specificity of our aId for the binding site of anti-MOMP MAb is further suggested by the binding inhibition of affinity-purified aId to DP10 by the synthetic peptide defined by the idiotype. In addition, these aId also reacted with anti-MOMP antisera from rats and mice, suggesting an idiotypic cross-reactivity between these species. Finally, immunization of naive mice with aId induced an antibody response directed against the peptide defined by our anti-MOMP MAb and with neutralizing activity. Taken together, these data suggest that aId mimic a neutralization site on MOMP and could serve as a surrogate antigen to induce protective immunity against Chlamydia trachomatis.

Amino Acid Sequence↗

PubMed1994

Characterization of the humoral response induced by a synthetic peptide of the major outer membrane protein of Chlamydia trachomatis serovar B.

The major outer membrane protein of Chlamydia trachomatis has been extensively studied and is still considered one of the most promising candidates for development of a synthetic vaccine. Neutralizing epitopes in variable domains I, II, and IV have already been reported. In variable domain I, residues 69 to 78 have been identified as a neutralizing epitope for some of the C- and C-related complex serovars (A, C, I, J, L3, and K). It is not known whether epitopes located at the same position in B-complex serovars are neutralizing. To clarify this point, rabbit polyclonal antibodies directed against the peptide 69TTTGNAVAPS78 from the B serovar were produced. Rabbit antisera were further rendered peptide specific by purification on a peptide-bovine serum albumin-Sepharose affinity column. Peptide-specific rabbit immunoglobulin reacted with five of the B-complex serovars (B, Ba, E, L1, and L2) by immunoblot and by direct-binding enzyme-linked immunosorbent assay. Furthermore, this peptide-specific rabbit immunoglobulin neutralized the chlamydial infectivity of both serovars B and E for HaK cells in a complement-independent in vitro assay. The importance of these results stems from the fact that peptide 69TTTGNAVAPS78 was able to induce an antibody response directed against B- and B-related complex serovars, including serovar E, which is responsible for a high proportion of genital infections. This peptide could therefore be considered for the construction of a multivalent synthetic vaccine.

Amino Acid Sequence↗

PubMed1994

Pathophysiology and treatment of negative symptoms.

The assessment and clinical characterization of the negative symptoms of schizophrenia are reviewed. While negative symptoms may be secondary to positive symptoms, extrapyramidal side-effects, depressive illness, chronic institutionalization or other factors, they may also be primary, i.e., integral to the disease process itself. Recent literature has suggested that negative symptoms may represent a distinct pathophysiological process mediated in part by serotonergic mechanisms. Atypical neuroleptics, which have dual effects on D2/5-HT2 receptors, have demonstrated clinical efficacy on both negative and positive symptoms of schizophrenia, and might help to clarify the pathogenesis of these symptom clusters.

Antipsychotic Agents↗

PubMed1993

[Pheochromocytoma of the broad ligament].

The authors report a rare case where a pheochromocytoma which was not in the adrenal gland occurred in the broad ligament. A review of the literature resulted in only three published cases being found. When the symptomatology suggests that there may be a pheochromocytoma in the body one has to research where it is sited and one has to think of such a possibility if a tumour in the broad ligament is found during an operation, so that the risks of operating on these tumours can be lessened.

Adnexal Diseases↗

PubMed1992

[Duration of antidepressive treatments].

In spite of the considerable amount of research undertaken in the field of biological psychiatry, there is currently no reliable guide allowing us to predict with accuracy the response of a patient to an antidepressant treatment. Moreover, owing to the heterogeneity of the spectrum of affective disorders, to the importance of eliminating the various factors involved in an apparent resistance to an antidepressant therapy, it seems aleatory, particularly for an individual patient, to foresee precisely the length of an antidepressant treatment, except may be in unipolar disorders. The quality of the physician-patient therapeutic relationship should never be neglected. The recent hypotheses pertaining to the etiopathogenesis of affective disorders, the advent of new psychotropic agents such as the specific serotonin uptake inhibitors, or other agents not acting through this mechanism and the MAOI, type A, as well as the utilization of corticosuppressor drugs, may pave the way to new therapeutic avenues that could, in the future, modify the prognosis and the duration of the treatment of the depressive affective disorders.

Antidepressive Agents, Tricyclic↗

PubMed1992

[Mediastinal parathyroid adenomas on a 5th ectopic gland. 2 case reports].

Mediastinal parathyroid adenoma located on the 5th ectopic gland is rare. We report here two new cases diagnosed by scintigraphy. In one case the adenoma was found to be located in the mediastinum prior to cervicotomy. The modern imaging methods capable of locating parathyroid adenomas are evaluated.

Adenoma↗