Alien Registration- Arsenault, Marie (Rumford, Oxford County)

https://digitalmaine.com/alien_docs/13539/thumbnail.jp

Alien Registration- Arsenault, Marie Jeanne (Rumford, Oxford County)

https://digitalmaine.com/alien_docs/13437/thumbnail.jp

Aortic valve sclerosis in rabbits

BACKGROUND AND AIM OF THE STUDY: Aortic valve sclerosis is fairly common and is currently seen as a marker of systemic atherosclerosis. For unclear reasons only a minority of those sclerotic valves will evolve to become stenotic suggesting that atherogenic factors alone are insufficient to explain the development of valve stenosis. We had reported in a model of cholesterol fed rabbits that a combination of high cholesterol with vitamin D supplementation was necessary to induce valve stenosis and significant calcium deposition whereas high cholesterol alone only induced a sclerosis of the valve. In this study, we further evaluated the role of vitamin D treatment in the development of aortic valve disease (sclerosis or stenosis) in this rabbit model. METHODS: Rabbits were divided in 4 groups followed for 12 weeks: 1) no treatment; 2) cholesterol-enriched diet, 3) cholesterol-enriched diet + vitamin D2 (VD; 50000IU, daily) 4) VD alone for 12 weeks. Echocardiographic assessment of the aortic valve was done at baseline, and every 4 weeks thereafter. Aortic valve area, maximal and mean transvalvular gradients were recorded and compared over time. Immunohistological study of the valves of AS rabbits was also realized for several classical atherosclerosis markers. RESULTS: Vitamin D2 treated animal did not develop any stenosis of the valve despite increased echogenicity due to diffuse calcium deposits on the leaflets without any atherosclerotic lesions. Only the combination of high cholesterol with VD resulted in a decrease of aortic valve area. Immunohistological analysis of aortic valves from VD rabbits showed the presence of calcium deposits, T-cell infiltration in addition to positive labeling for alpha-smooth muscle cell actin. We did not observe macrophage infiltration in aortic valve leaflets of VD rabbits. CONCLUSION: Hypercholesterolemia or vitamin D supplements alone could not induce aortic valve stenosis in our animal model whereas the combination resulted in a decreased aortic valve area. These findings support the hypothesis that a combination of atherosclerotic and calcifying factors is necessary to induce aortic valve stenosis in this model

A Western high fat/high carbohydrate diet induces aortic valve disease in C57BL/6J mice

Objectives : The purpose of this study was to compare aortic valve function and morphology in adult wild-type (WT) mice and in low-density lipoprotein receptor-deficient (LDLr−/−) mice fed or not fed a high-fat/high-carbohydrate (HF/HC) diet. Background : Observations suggest a link between degenerative aortic valve stenosis (AS) and atherosclerosis. Aortic valve stenosis has been successfully induced in animal models of extreme hypercholesterolemia, but these models are less relevant to humans. It is not known if a proatherogenic HF/HC diet without added cholesterol could have the same negative impacts. Methods : Forty C57BL/6J mice were divided into four groups: WT + normal diet, WT + HF/HC diet, LDLr−/− with a normal diet, and LDLr−/− with a HF/HC diet. Aortic valve function and histology were evaluated by echocardiography after four months. Results : Wild-type mice on a HF/HC diet became mildly hypercholesterolemic, obese, and hyperglycemic. As expected, LDLr−/− mice became severely hypercholesterolemic. Both WT and LDLr−/− mice on a HF/HC diet displayed smaller valve areas and higher transvalvular velocities (p < 0.01) after four months. Aortic valve leaflets were thicker and infiltrated with lipids and macrophages in both HF/HC groups. Conclusions : A HF/HC diet in mice results in significant aortic valve abnormalities. Putting WT mice on a HF/HC diet reproduced a combination of atherogenic factors (obesity, mild dyslipidemia, and hyperglycemia) more commonly encountered in humans than isolated severe hypercholesterolemia. Severe hypercholesterolemia was not a prerequisite in our model. This experimental model suggests that AS development is multifactorial and that hypercholesterolemia should not be the only target in this disease

Early endothelial dysfunction in cholesterol-fed rabbits: a non-invasive in vivo ultrasound study.

BACKGROUND: Endothelial function in hypercholesterolemic rabbits is usually evaluated ex vivo on isolated aortic rings. In vivo evaluation requires invasive imaging procedures that cannot be repeated serially. AIM: We evaluated a non-invasive ultrasound technique to assess early endothelial function in rabbits and compare data with ex vivo measurements. METHODS: Twenty-four rabbits (fed with a cholesterol diet (0.5%) for 2 to 8 weeks) were given progressive infusions of acetylcholine (0.05–0.5 μg/kg/min) and their endothelial function was assessed in vivo by transcutaneous vascular ultrasound of the abdominal aorta. Ex vivo endothelial function was evaluated on isolated aortic rings and compared to in vivo data. RESULTS: Significant endothelial dysfunction was demonstrated in hypercholesterolemic animals as early as 2 weeks after beginning the cholesterol diet (aortic cross-sectional area variation: -2.9% vs. +4% for controls, p < 0.05). Unexpectedly, response to acetylcholine at 8 weeks was more variable. Endothelial function improved in 5 rabbits while 2 rabbits regained a normal endothelial function. These data corroborated well with ex vivo results. CONCLUSION: Endothelial function can be evaluated non-invasively in vivo by transcutaneous vascular ultrasound of the abdominal aorta in the rabbit and results correlate well with ex vivo data

Fenofibrate and left ventricle remodeling in volume overload

Aims : Fenofibrate is a peroxisome proliferator-associated receptor alpha agonist (PPARα) used clinically for the management of dyslipidemia and is a myocardial fatty acid oxidation stimulator. It has also been shown to have cardiac anti-hypertrophic properties but the effects of fenofibrate on the development of eccentric LVH and ventricular function in chronic left ventricular (LV) volume overload (VO) are unknown. This study was therefore designed to explore the effects of fenofibrate treatment in a VO rat model caused by severe aortic valve regurgitation (AR) with a focus on cardiac remodeling and myocardial metabolism. Main methods : Male Wistar rats were divided in four groups (13–15 animals/group): Shams (S) treated with fenofibrate (F; 100 mg/kg/d PO) or not (C) and severe AR receiving or not fenofibrate. Treatment was started one week before surgery and the animals were sacrificed 9 weeks later. Key findings : AR rats developed severe LVH (increased LV weight) during the course of the protocol. Fenofibrate did not reduce LV weight. However, eccentric LV remodeling was strongly reduced by fenofibrate in AR animals. Fractional shortening was significantly less affected in ARF compared to ARC group. Fenofibrate also increased the myocardial enzymatic activity of enzymes associated with fatty acid oxidation while inhibiting glycolytic enzyme phosphofructokinase. Significance : Fenofibrate decreased LV eccentric remodeling associated with severe VO and helped maintain systolic function. Studies with a longer follow-up will be needed to assess the long-term effects of fenofibrate in chronic volume overload caused by aortic regurgitation

Multiple short-chain dehydrogenases/reductases are regulated in pathological cardiac hypertrophy.

Cardiac hypertrophy (CH) is an important and independent predictor of morbidity and mortality. Through expression profiling, we recently identified a subset of genes (Dhrs7c, Decr, Dhrs11, Dhrs4, Hsd11b1, Hsd17b10, Hsd17b8, Blvrb, Pecr), all of which are members of the short-chain dehydrogenase/reductase (SDR) superfamily and are highly expressed in the heart, which were significantly dysregulated in a rat model of CH caused by severe aortic valve regurgitation (AR). Here, we studied their expression in various models of CH, as well as factors influencing their regulation. Among the nine SDR genes studied, all but Hsd11b1 were downregulated in CH models (AR rats or mice infused with either isoproterenol or angiotensin II). This regulation showed a clear sex dimorphism, being more evident in males than in females irrespective of CH levels. In neonatal rat cardiomyocytes, we observed that treatment with the alpha-1 adrenergic receptor agonist, phenylephrine, mostly reproduced the observations made in CH animals models. Retinoic acid, on the other hand, stimulated the expression of most of the SDR genes studied, suggesting that their expression may be related to cardiomyocyte differentiation. Indeed, levels of expression were found to be higher in the hearts of adult animals than in neonatal cardiomyocytes. In conclusion, we identified a group of genes modulated in animal models of CH and mostly in males. This could be related to the activation of the fetal gene expression program in pathological CH situations, in which these highly expressed genes are down-regulated in the adult heart

Chronic high-fat diet-induced obesity decreased survival and increased hypertrophy of 2 rats with experimental eccentric hypertrophy from chronic aortic regurgitation.

Background : The composition of a diet can influence myocardial metabolism and development of left ventricular hypertrophy (LVH). The impact of a high-fat diet in chronic left ventricular volume overload (VO) causing eccentric LVH is unknown. This study examined the effects of chronic ingestion of a high-fat diet in rats with chronic VO caused by severe aortic valve regurgitation (AR) on LVH, function and on myocardial energetics and survival. Methods : Male Wistar rats were divided in four groups: Shams on control or high-fat (HF) diet (15 rats/group) and AR rats fed with the same diets (ARC (n = 56) and ARHF (n = 32)). HF diet was started one week before AR induction and the protocol was stopped 30 weeks later. Results : As expected, AR caused significant LV dilation and hypertrophy and this was exacerbated in the ARHF group. Moreover, survival in the ARHF group was significantly decreased compared the ARC group. Although the sham animals on HF also developed significant obesity compared to those on control diet, this was not associated with heart hypertrophy. The HF diet in AR rats partially countered the expected shift in myocardial energy substrate preference usually observed in heart hypertrophy (from fatty acids towards glucose). Systolic function was decreased in AR rats but HF diet had no impact on this parameter. The response to HF diet of different fatty acid oxidation markers as well as the increase in glucose transporter-4 translocation to the plasma membrane compared to ARC was blunted in AR animals compared to those on control diet. Conclusions : HF diet for 30 weeks decreased survival of AR rats and worsened eccentric hypertrophy without affecting systolic function. The expected adaptation of myocardial energetics to volume-overload left ventricle hypertrophy in AR animals seemed to be impaired by the high-fat diet suggesting less metabolic flexibility

Comment susciter l'intérêt du lecteur : analyse de contenu de 38 guides rédactionnels

Cette étude traite du concept de l’intérêt (à susciter chez le lecteur) dans les guides de rédaction professionnelle. Une analyse de contenu de 38 livres électroniques sur la rédaction nous a permis d’observer la prise en compte et la variété du concept de l’intérêt. Les discours sur l'intérêt portent essentiellement sur l’importance de le créer ainsi que sur les moyens pour le susciter. Parmi les 21 sous-catégories de moyens qui se sont manifestées dans le discours des auteurs, les 5 principales concernent l’importance de cibler le lecteur (50 énoncés, 17 sources), d'attirer l'attention (42 énoncés, 22 sources), d’être pertinent (22 énoncés, 12 sources), d’être concis (16 énoncés, 13 sources) et d’écrire avec simplicité (14 énoncés, 11 sources)

Étude de facteurs génétiques prédictifs dans le neuroblastome, en particulier les anomalies du chromosmoe 14q

Le neuroblastome (NB) représente 8% de tous les cancers pédiatriques et est caractérisé par sa grande hétérogénéité clinique. Afin d’évaluer son pronostic, plusieurs facteurs génétiques sont utilisés : amplification de MYCN, délétion 1p, gain 11q et gain 17q. Les buts de notre travail étaient d’abord de vérifier si l’hybridation in situ en fluorescence (FISH) permet une analyse complète de ces anomalies et ensuite, en utilisant une analyse globale du génome telle le polymorphisme nucléotidique simple (SNP), de vérifier la concordance avec les résultats de la FISH et le pronostic potentiel des anomalies du 14q, en particulier du gène AKT. Nous avons donc établi un panel de sondes pour la FISH qui a été appliqué sur 16 tumeurs non-fixées. Après isolation de l’ADN de 36 tumeurs, nous avons effectué une analyse génotypique par SNP utilisant les puces « Affymetrix Genome-Wide Human SNP Array 6.0 » contenant 945,826 sondes non polymorphiques et 906,000 sondes polymorphiques. Nos résultats ont démontré que la FISH permet l’évaluation complète des anomalies génétiques importantes du NB et que les anomalies déséquilibrées sont détectées très précisément par SNP. Les anomalies du 14q tendent à être associées avec des facteurs cliniques comme le grade et l’évolution, contrairement aux anomalies d’AKT. L’analyse du 14q a révélé trois gènes d’intérêt, MAX, BCL11B et GPHN, qui devraient être analysés sur un plus grand échantillon. Ainsi, l’étude par FISH semble adaptée pour détecter les anomalies génétiques classiques du NB, alors que celles retrouvées en 14q représentent de potentielles cibles thérapeutiques pour cette tumeur.Neuroblastoma (NB) accounts for 8% of all childhood cancers and is characterized by its clinical heterogeneity. To evaluate its prognostic, many genetic markers are used: MYCN amplification, 1p deletion, 11q gain and 17q gain. Our goals were first to verify if fluorescence in situ hybridization (FISH) allows a complete analysis of these abnormalities and, second, using a global genomic analysis as single nucleotide polymorphism (SNP), to verify the concordance with FISH results and the prognostic potential of 14q abnormalities, especially these of AKT gene. We then established a FISH panel that has been applied on 16 unfixed tumors. After DNA isolation of 36 tumors, we made a genotypic analysis by SNP using « Affymetrix Genome-Wide Human SNP Array 6.0 » containing 945,826 nonpolymorphic probes and 906,000 polymorphic probes. Our results have demonstrated that FISH allows a complete evaluation of the NB’s important genetic abnormalities and that unbalanced abnormalities are detected very precisely by SNP. 14q abnormalities seem to be associated with clinical factors such as tumor grading and evolution, unlike AKT abnormalities. Analysis of 14q abnormalities revealed three genes of interest, MAX, BCL11B and GPHN, which should be analyzed on a larger sample. Thereby, FISH study seems appropriate to detect the NB’s classic genetic abnormalities, while those found in 14q represent potential therapeutic targets for this tumor