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result(s) for
"Thibeault, Diane"
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The human renin infused rat: use as an in vivo model for the biological evaluation of human renin inhibitors
by
Jaramillo, Jorge
,
Anderson, Paul
,
Vigeant, Jean-Claude
in
Administration, Oral
,
Angiotensin I - biosynthesis
,
Angiotensin-Converting Enzyme Inhibitors - pharmacology
1999
The human renin infused rat model (HRIRM) was used as an in vivo small-animal model for evaluating the efficacy of a collection of inhibitors of human renin. The intravenous infusion of recombinant human renin (2.4 µg·kg
-1
·min
-1
) in the ganglion-blocked, nephrectomized rat produced a mean blood pressor response of 47 ± 3 mmHg (1 mmHg = 133.3 Pa), which was reduced by captopril, enalkiren, and losartan in a dose-dependent manner following oral administration, with ED
50
values of 0.3 ± 0.1, 2.5 ± 0.9, and 5.2 ± 1.6 mg/kg, respectively. A series of peptidomimetic P
2
-P
3
butanediamide renin inhibitors inhibited purified recombinant human renin in vitro in a concentration-dependent manner, with IC
50
values ranging from 0.4 to 20 nM at pH 6.0, with a higher range of IC
50
values (0.8-80 nM) observed at pH 7.4. Following i.v. administration of renin inhibitors, the pressor response to infused human renin in the HRIRM was inhibited in a dose-dependent manner, with ED
50
values ranging from 4 to 600 µg/kg. The in vivo inhibition of human renin following i.v. administration in the rat correlated significantly better with the in vitro inhibition of human renin at pH 7.4 (r = 0.8) compared with pH 6.0 (r = 0.5). Oral administration of renin inhibitors also resulted in a dose-dependent inhibition of the pressor response to infused human renin, with ED
50
values ranging from 0.4 to 6.0 mg/kg and the identification of six renin inhibitors with an oral potency of <1 mg/kg. The ED
50
of renin inhibitors for inhibition of angiotensin I formation in vivo was highly correlated (r = 0.9) with the ED
50
for inhibition of the pressor response. These results demonstrate the high potency, dose dependence, and availability following oral administration of the butanediamide series of renin inhibitors.Key words: renin-angiotensin system, recombinant human renin, rat, renin inhibitors.
Journal Article
Treatment of Vocal Fold Scarring: Rheological and Histological Measures of Homologous Collagen Matrix
by
Thibeault, Susan L.
,
Chan, Roger W.
,
Bless, Diane M.
in
Animals
,
Biological and medical sciences
,
Biomechanical Phenomena
2002
The current treatment options for dysphonia secondary to vocal fold scarring are limited. Few studies address changes in the lamina propria, which is critical to vocal fold biomechanical properties and voice production. Using rheological and histological measures of homologous collagen matrix (HCM)–injected vocal folds, we assessed HCM's potential for providing bulk and restoring biomechanical performance. Twenty rabbits underwent bilateral vocal fold scarring. After 10 weeks of scar maturation, the rabbits had unilateral injections of HCM or saline solution. Ten weeks after the injections, histological studies revealed well-defined collagen globules distributed throughout the lamina propria and underlying muscular tissue. Significantly more procollagen was observed in the HCM-treated group. No significant differences in elastic shear modulus or dynamic viscosity were found between the treatment groups. This study demonstrates that HCM is an inert, relatively stable injectate that may serve well for medialization but does not appear to improve the dynamic properties of the lamina propria.
Journal Article
Quantitative Assessment of Human Endometriotic Tissue Maintenance and Regression in a Noninvasive Mouse Model of Endometriosis
by
Lépine, Manon
,
Rancourt, Claudine
,
Merlen, Yannick
in
Adenoviridae - genetics
,
Animals
,
Cell death
2004
Endometriosis is a prevalent disease characterized by the estrogen-dependent ectopic growth of endometrial tissue. Most of the current medical therapies consist in inducing a hypoestrogenic state in patients, but these treatments are associated with severe side effects and high recurrence rates. The development of convenient and reliable endometriosis animal models would be instrumental to accelerate the emergence of new therapeutic alternatives. Recently, we developed an improved experimental model for endometriosis, relying on the infection of human endometrial fragments by an adenovirus carrying the green fluorescent protein. Following injection of fluorescent fragments into nude mice, the implantation and growth of endometriotic-like lesions could be followed noninvasively. In the present work, we demonstrate that this model can be used to quantify the size of fluorescent endometriotic lesions by in vivo imaging. To this end, we repeatedly measured lesion size over a 4-week period in mice supplemented or not with estradiol. The model was adequate to confirm previous results showing that estrogen is dispensable for the implantation phase of endometrial tissue, whereas it is required for lesion maintenance. As a proof of concept for inducing regression of established lesions, ganciclovir was used to treat animals implanted with human fluorescent endometrial fragments expressing thymidine kinase. A significant decrease in lesion size was observed by in vivo imaging in ganciclovir-treated mice. Together, the data indicate that the noninvasive animal model described here provides a tool for drug testing and/or gene target validation in endometriosis.
Journal Article
Hepatocyte Growth Factor and its Receptor C-Met in Rat and Rabbit Vocal Folds
by
Hirano, Shigeru
,
Thibeault, Susan
,
Bless, Diane M.
in
Animals
,
Biological and medical sciences
,
Ent. Stomatology
2002
Vocal fold fibrotic scar is characterized by fibrosis of the lamina propria and epithelium, and is difficult to treat. Hepatocyte growth factor (HGF) has antifibrotic activity and has received attention as a possible therapeutic alternative to treat fibrosis. In this study, in order to clarify whether HGF can be involved in vocal fold scarring, we examined the existence of HGF and its receptor, c-Met, in rat vocal folds, and then the activity of HGF in rabbit injured vocal folds, using immunohistochemistry and enzyme-linked immunosorbent assay. We found HGF and c-Met on epithelial cells and gland cells of the rat vocal folds. On the injured vocal folds of rabbits, little HGF was observed immediately after injury, but prominent activity occurred simultaneously with reepithelialization of the vocal fold mucosa on days 10 to 15. The activity of HGF was observed on fibroblasts in the lamina propria, as well as the epithelium. It is suggested that HGF in the vocal folds is produced by the fibroblasts and delivered to the epithelium. The implication of these findings is that HGF is involved in wound healing of the vocal fold, and may provide an alternative approach in preventing and treating vocal fold scarring.
Journal Article
Introducing an Evaluation of Community Based Occupational Therapy Services: A Client-Centred Practice
by
Boisvenu, Michèle
,
Laporte, Diane
,
Landry, Anic
in
Basic Skills
,
College Science
,
Communities
2000
The results of a study conducted in 1996 by the “Groupe de recherche en ergothérapie communautaire” (GREC), indicate that the quality of occupational therapy services in community settings is infrequently evaluated. A conceptual framework supporting such a process is presented in the context of client-centered services with a focus on continuous health care improvement. Both the research process leading to the design of an assessment tool, and its congruence with the beliefs and values of the profession, are explored. Finally, some issues relating to the implementation of a formal evaluation process are discussed.
Journal Article