Introduction: Developmental origins of disease refers to the theory that adverse maternal environments influence fetal development and the risk of cardiovascular disease (CVD) in adulthood. To test the hypothesis that gestational hypertension influences the development of CVD in offspring, a novel experimental paradigm was developed using atrial natriuretic peptide gene disrupted mice (ANP-/-). The objective of this thesis was to determine the effect of gestational hypertension on cardio-renal function in offspring. Methods: ANP+/+ females were crossed with ANP-/- males (yielding ANP+/-WT offspring) and ANP-/- females with ANP+/+ males (yielding ANP+/-KO offspring). Previous work has established that ANP-/- dams are hypertensive during pregnancy. Offspring gene expression was measured using qPCR. Offspring arterial blood pressure (BP) was measured with a non-invasive tail cuff system. Offspring left ventricular (LV) function was examined using echocardiography (ECHO). Offspring were treated with normal salt (NS) or high salt (HS) chow for five weeks to assess salt-sensitivity. Daily injections of isoproterenol (ISO) were used to induce cardiac stress in offspring. Collagen deposition was assessed using Masson’s trichrome and picrosirius red staining. Results: Absence of maternal ANP had no effect on either litter size or offspring growth, but caused significant LV hypertrophy in offspring, with no change in LV function. Treatment with ISO resulted in myocardial fibrosis and significant LV diastolic dysfunction with a restrictive filling pattern (increased E/A ratio and E/e’) only in ANP+/-KO offspring. Furthermore, absence of maternal ANP was associated with salt-resistant BP in offspring. Conclusions: Gestational hypertension using the ANP-/- mouse model results in a salt-resistant phenotype in offspring, as well as significant cardiac hypertrophy and an adverse response to activation of the sympathetic nervous system in adult offspring. These data suggest that adverse maternal environments may increase the risk of cardiovascular disease in offspring later in life. / Thesis (Ph.D, Anatomy & Cell Biology) -- Queen's University, 2012-09-18 16:12:01.147

No description available.

Fibroblast growth factor-2 (FGF-2) is expressed as high molecular weight (> 20 kDa, Hi-FGF-2), or low molecular weight, (18 kDa, Lo-FGF-2) isoforms with distinct functions in the heart and other tissues. Studies to-date have focused on Lo-FGF-2, while the biology of Hi-FGF-2 is less well understood. This work investigated potential autocrine and paracrine effects of rat and human Hi-FGF-2 on cardiac myocytes and non-myocytes (myofibroblasts). Using rat ventricular myofibroblast cultures stimulated with angiotensin II (Ang II), in the absence or presence of YVAD, a peptide inhibitor of caspase-1, it was shown that caspase-1 activity was required for the Ang II-stimulated Hi-FGF-2 secretion. Secreted rat Hi-FGF-2 was shown to be biologically active and capable of stimulating neonatal as well as adult cardiomyocyte hypertrophy in vitro. The effect of extracellular-acting Hi- versus Lo-FGF-2 on the secretome profile of rat cardiac myofibroblasts was compared. Conditioned media collected after stimulation with rat Hi- or Lo-FGF-2 were analyzed by mass spectroscopy (LC-MS/MS). Secretome profiles suggested that Hi-FGF-2 was more potent than Lo-FGF-2 in upregulating several matricellular and fibrosis-associated proteins, most prominently periostin, follistatin-like protein 1, plasminogen activator inhibitor-1, and tenascin. Human heart (atrial) tissue, pericardial fluid, and human heart-derived myofibroblasts were shown to accumulate predominantly Hi-FGF-2. Ang II up-regulated Hi-FGF-2 in human cells, via activation of: type 1 or type 2 Ang II receptors (AT-1R, AT-2R); the ERK pathway; and matrix metalloprotease-2. Neutralizing antibodies specific for Hi-FGF-2 (neu-AbHi-FGF-2) reduced expression of proteins associated with fibroblast-to-myofibroblast conversion and fibrosis. Blocking the autocrine action of Hi-FGF-2 on human cells with neu-AbHi-FGF-2 resulted in down-regulation of periostin, as well as α-smooth muscle actin, pro-collagen, embryonic smooth muscle myosin, and extra domain A fibronectin, consistent with a reversal from activated myofibroblast to fibroblast phenotype. Stimulation of human myofibroblasts with human Hi-FGF-2 was significantly more potent than Lo-FGF-2 in upregulating pro-interleukin-1β and plasminogen activator inhibitor-1, considered to be pro-inflammatory proteins. It is concluded that exported, extracellular-acting Hi-FGF-2 has pro-fibrotic, pro-inflammatory, and pro-hypertrophic properties, contributes to the ‘activated fibroblast’ phenotype, and represents a therapeutic target for prevention of maladaptive cardiac remodeling in humans.

国立情報学研究所で電子化したコンテンツを使用している。

国立情報学研究所で電子化したコンテンツを使用している。

国立情報学研究所で電子化したコンテンツを使用している。 / 国立情報学研究所で電子化したコンテンツを使用している。

Diss. (sammanfattning) Stockholm : Karol. inst., 2002. / Härtill 5 uppsatser.

Altas doses de esteróides anabólicos androgênicos (EAA) são utilizadas, sem indicação terapêutica, por indivíduos que visam aumentara força muscular ou melhorar a aparência física. Entretanto, os efeitos benéficos destas substâncias sobre o desempenho atlético são questionáveis, e sabe-se que esta prática é acompanhada de muitos efeitos colaterais. Este estudo teve por objetivo analisar as alterações histológicas e morfométricas das fibras do músculo sóleo e melhora no desempenho de ratos submetidos a um programa de treinamento físico, associado ou não à administração do esteróide anabólito decanoato de nandrolona. Os animais foram divididos em quatro grupos: sedentário + veículo (SC); treinado + veículo (TC); sedentário + EAA (SE); treinado + EAA (TE). Os animais foram tratados, por 4 semanas, com veículo (propilenoglicol, 0,2 mL/Kg) ou decanoato de nandrolona (Deca-Durabolin, 5 mg/Kg), i.m., 1 x/semana. O treinamento físico foi realizado através de saltos em meio líquido (4 séries, 10 repetições, 60 segundos de intervalo entre as séries), 50-80% do peso corporal, 3 dias/semana, 4 semanas. Antes e após o treinamento os animais foram submetidos a um teste de fadiga. Após o sacrifício, o músculo sóleo direito foi retirado. Cortes do terço médio desse músculo foram feitos em micrótomo criostato e corados pela técnica HE. Os animais submetidos ao treinamento físico (TC) e (TE) apresentaram fibras musculares com maior área, quando comparados com os animais controle (SC e SE). Não foram observadas diferenças no desempenho entre os grupos. Os resultados sugerem que o treinamento físico produz hipertrofia de forma semelhante, tanto no grupo que recebeu EAA quanto no que recebeu óleo mineral. No entanto, o grupo TE apresentou sinais de maior degeneração. / High doses of anabolic androgenic steroids (AAS) are used without therapeutic indication in order to increase the muscle power or improve the physical appearance. However the beneficial effects of AAS on the athletic performance are still questionable and it is well established that AAS abuse is associated with many detrimental side-effects. The objective of this study was to analyze the histological and morphometrical alterations of the fibers from the soleum muscle and performance improvement of rats submitted to a physical training, associated not to the administration of the anabolic steroid decanoate of nandrolone. Male Wistar rats were divided into four groups: sedentary + vehicle (SC), trained + vehicle (TC), sedentary + AAS (SE) and trained + AAS (TE). The animals were treated for 4 weeks with vehicle (propyleneglycol, 0.2 mL/Kg) or nandrolone decanoate (Deca-Durabolin, 5 mg/Kg), i.m., 1x/week. Training was performed by jumping into water (4 sets, 10 repetitions, 60 seconds rest), 50-80% body weight-load, 3 days/week, 4 weeks). Before and after training the animals were submitted a test of fatigue. After sacrifice, the right soleum muscle was removed. Third middle cuts of this muscle were made in microtome cryostat and stained through HE technique. The animals submitted to physical training (TC) and (TE) presented muscle fibers with bigger area when compared to the ones from the control group (SC and SE). Performance improvement of all experimental groups was not altered. The results suggest that physical training produces muscle hypertrophy similarly, not only in the group that received AAS, but also in the one that received mineral oil. However, the group TE presented signs of greater muscle degeneration.

Cardiac hypertrophy is a fundamental response to an increased workload on the heart characterized by cardiac myocyte (CM) growth and left ventricular (LV) wall thickening. In a model of hypertension, e.g. chronic pressure overload, this process may become maladaptive, initially leading to impaired myocardial relaxation and LV filling, and subsequently to LV dilation, wall thinning, and contractile failure. Hemodynamic overload activates Gαq-mediated signaling responsible for transcriptional reactivation of fetal growth programs, activation of the mitogen-activated protein kinase (MAPK) cascade, and oxidative stress. The precise mechanism by which MAPK is activated in pressure overload, and the role oxidative stress plays in mediating this hypertrophic signaling are still under investigation. In CMs, the sarcoplasmic/endoplasmic reticulum calcium ATPase (SERCA) maintains calcium stores, and thus may regulate calcium-dependent MAPK signaling. Our laboratory showed that SERCA is activated in CMs by reversible oxidative post-translational modification (OPTM) of its most reactive cysteine site (C674). We hypothesized that OPTMs mediate the effects of hypertrophic stimuli in CMs via reversible oxidation of SERCA at C674. To test this hypothesis, we employed a reductionist model: isolated adult rat ventricular myocytes (ARVM) overexpressing wild-type (WT) or mutant SERCA, in which C674 is substituted with a redox-insensitive serine (C674S). Using alpha-adrenergic receptor (αAR) stimulation as a model of Gq-mediated hypertrophy, we found that C674S expression decreased both CM growth and MAPK activation. Furthermore, biotin switch revealed that αAR stimulation induced a reversible OPTM of SERCA at C674. We generated a transgenic mouse expressing a single-allele C674S SERCA2 knock-in mutation (SKI) to explore this mechanism further in the setting of pressure overload, a disease model of Gq-activation in vivo. SKI mice subjected to ascending aortic constriction (AAC) had decreased hypertrophy compared to WT. Ventricular myocytes isolated from adult SKI mice also had diminished MAPK activation in response to hypertrophic stimulation in vitro and decreased SERCA function at baseline. These findings led us to the conclusion that redox-activation of SERCA via reversible modification of C674 is critical for the complete transduction of hypertrophic stimuli to MAPK signaling and CM hypertrophy.

abstract: Eccentric muscle action (ECC) occurs when the force exerted by a working muscle is less than that of an outside resistance. This is characterized by muscle lengthening, despite actin-myosin crossbridge formation. Research has indicated that muscles acting eccentrically are capable of producing more force when compared to muscles acting concentrically. Further, research has shown ECC muscle actions may have different fatigue patterns that CON actions. The purpose of this study was to determine if a) ECC bench press yields greater strength than concentric (CON) as measured by one-repetition maximum (1RM), b) there is a difference between the number of repetitions that can be completed concentrically and eccentrically under the same relative intensities of 1RM (90%, 80%, 70%, 60%), c) a prediction model may be able to predict ECC 1RM from CON 1RM or CON repetitions to fatigue. For this study, 30 healthy males (age = 24.63 + 5.6 years) were tested for 1RM in CON and ECC bench press, as well as the number of repetitions they were able to complete at various intensities of mode-specific 1RM. A mechanical hoist was affixed to a gantry crane and placed over a standard weightlifting bench. The hoist was connected to 45lb plates that were loaded on a standard barbell, which allowed for mechanical raising and lowering of the barbell. For CON repetitions, the weight was mechanically lowered to the chest and the participant pressed it up. For ECC repetitions, the weight was mechanically raised and the participant lowered it. Paired t-tests showed that ECC 1RM was significantly (p < 0.05) greater than CON 1RM (ECC =255.17 + 68.37lbs, CON = 205.83 + 58.43lbs). There was a significant difference (p < 0.05) between the number of repetitions completed at 90% 1RM (CON = 4.57 + 2.21 repetitions, ECC = 7.67 + 3.24 repetitions). There were no differences in repetitions completed at any other intensity 1RM. CON 1RM and the number of repetitions completed with two different absolute loads (130-150lbs and 155-175lbs) concentrically and eccentrically were valid predictors of ECC 1RM. These data indicate that ECC actions yield increased force capabilities than CON actions, there is no difference in the rate of the fatigue, and ECC 1RM may be predicted from various CON tests. / Dissertation/Thesis / Ph.D. Physical Activity, Nutrition and Wellness 2013