Studies of myocardial aging are complex and the mechanisms involved in the deterioration of ventricular performance and decreased functional reserve of the old heart remain to be properly defined. We have studied a colony of beagle dogs from 3 to 14 yr of age kept under a highly regulated environment to define the effects of aging on the myocardium. Ventricular, myocardial, and myocyte function, together with anatomical and structural properties of the organ and cardiomyocytes, were evaluated. Ventricular hypertrophy was not observed with aging and the structural composition of the myocardium was modestly affected. Alterations in the myocyte compartment were identified in aged dogs, and these factors negatively interfere with the contractile reserve typical of the young heart. The duration of the action potential is prolonged in old cardiomyocytes contributing to the slower electrical recovery of the myocardium. Also, the remodeled repolarization of cardiomyocytes with aging provides inotropic support to the senescent muscle but compromises its contractile reserve, rendering the old heart ineffective under conditions of high hemodynamic demand. The defects in the electrical and mechanical properties of cardiomyocytes with aging suggest that this cell population is an important determinant of the cardiac senescent phenotype. Collectively, the delayed electrical repolarization of aging cardiomyocytes may be viewed as a critical variable of the aging myopathy and its propensity to evolve into ventricular decompensation under stressful conditions. aging; myocardium; contractile reserve NEW & NOTEWORTHYWe have investigated the effects of aging on the heart using a genetically uniform large animal model, maintained under highly regulated conditions. Our results indicate that the myocyte compartment undergoes physiological alterations with age that negatively interfere with ventricular function.STUDIES OF MYOCARDIAL AGING in humans are complex, as it is difficult to separate the effects of time from genetic, ethnic, lifestyle, and environmental factors, which may modify physiological cardiac aging. Additionally, the incidence of cardiovascular diseases increases with age (24) and intervening pathologies may change the natural temporal evolution of the organ. Therefore, the mechanisms involved in the age-related deterioration of ventricular performance and decreased functional reserve of the old heart (9, 12, 17, 18, 39) remain to be properly defined.The general belief has been that abnormalities in ventricular compliance with age occur as a result of collagen deposition and diffuse interstitial fibrosis, which, together with cardiomyocyte loss, lead to depressed systolic and diastolic function (17,18,26,39). Additionally, myocardial hypertrophy has been proposed as a critical variable of the senescent myopathy (5), in spite of the lack of organ hypertrophy in older humans (25). Current understanding of the pathophysiology of the aging myopathy and the mechanisms involved in the increased incidence of heart failure and ...

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Low-salt (LS) diet has been considered to be beneficial in the prevention and treatment of hypertension; however, it also increases plasma angiotensin (ANG) II and may cause adverse cardiovascular effects, such as endothelial dysfunction. We assessed endothelial function of coronary arterioles and vascular superoxide production, as a function of LS diet. Dogs were fed with LS (0.05% NaCl) or a normal-salt (NS, 0.65% NaCl) diet for 2 wk. There were threefold increases in plasma ANG II, associated with a 60% reduction in flow-induced dilation (FID) in coronary arterioles of LS compared with NS dogs. In vessels of NS dogs, FID was primarily mediated by nitric oxide (NO), as indicated by an eliminated FID by N(ω)-nitro-l-arginine methyl ester (l-NAME). In vessels of LS dogs, however, FID was eliminated. Administration of apocynin, a NAD(P)H oxidase inhibitor, partially restored FID and additional l-NAME eliminated FID. Generation of superoxide, measured with dihydroethidium, was significantly greater in vessels of LS than in NS dogs, which was further increased in response to ANG II or phorbol 12,13-dibutyrate, an agonist of protein kinase C (PKC). The enhanced superoxide was normalized by apocynin, losartan (a blocker of angiotensin type 1 receptor), and chelerythrine chloride (an antagonist of PKC). Western blotting indicated an upregulation of gp91(phox) and p47(phox), associated with increased expression of phosphorylated PKC in vessels of LS dogs. In separate experiments, dogs were fed simultaneously with LS and losartan (LS + Losa) for 2 wk. There was a significant increase in plasma ANG II in LS + Losa dogs, which, however, was associated with normal FID and gp91(phox) expression in coronary arterioles. In conclusion, LS led to endothelial dysfunction, as indicated by an impaired flow-induced dilation caused by decreasing NO bioavailibility, a response that involves angiotensin-induced activation of PKC that, in turn, activates vascular NAD(P)H oxidase to produce superoxide.

High-grade endometrial stromal sarcomas (HGESSs) are more aggressive and have higher rates of resistance to endocrine therapy than low-grade endometrial stromal sarcomas (LGESSs). The pathogenesis of hormonal resistance in these lesions has yet to be defined. Here we sought to histologically and genetically characterize 3 LGESSs and their recurrences that underwent histologic high-grade transformation following endocrine therapy. For this, DNA from primary tumors and select subsequent recurrences were subject to massively parallel sequencing targeting 468 cancer-related genes. Somatic mutation analyses were performed using validated bioinformatics methods. In addition, RNA from each case was evaluated for the presence of gene fusions using targeted RNA-sequencing. All patients initially presented with LGESS, developed HGESS recurrences, and received at least 2 lines of hormonal suppressive therapy. Gene fusions classically described as associated with LGESS were identified in all 3 cases, including JAZF1-PHF1, EPC1-PHF1 and JAZF1-SUZ12 fusions for Cases 1, 2 and 3, respectively. Targeted sequencing analysis revealed that none of the primary LGESS, however the HGESS recurrences of Cases 1 and 3, and the LGESS and HGESS recurrences of Case 2 post endocrine treatment harbored ESR1 p.Y537S hotspot mutations. These ESR1 ligand-binding domain mutations have been found as a mechanism of acquired endocrine resistance in breast cancer. Also, a reduction in estrogen receptor (ER) expression was observed in recurrences. Our findings suggest that the ESR1 p.Y537S hotspot mutation in LGESS with histologic high-grade transformation may be associated with endocrine resistance in these lesions. Furthermore, our data suggest that genetic analyses may be performed in recurrent LGESS following hormonal therapy, development of high-grade morphology, and/or altered/diminished ER expression.

Subclonal loss of mismatch repair (MMR) proteins has been described in a small subset of endometrial carcinomas (ECs), but the genomic basis for this phenomenon has received limited attention. Herein, we retrospectively evaluated all ECs with MMR immunohistochemistry (n=285) for subclonal loss, and in those (n=6), performed a detailed clinicopathologic and genomic comparison of the MMR-deficient and MMR-proficient components. Three tumors were FIGO stage IA, and one each stage IB, II, and IIIC2. Patterns of subclonal loss were as follows: (1) 3 FIGO grade 1 endometrioid carcinomas with subclonal MLH1/PMS2, MLH1 promoter hypermethylation, and no MMR gene mutations; (2) POLE-mutated FIGO grade 3 endometrioid carcinoma with subclonal PMS2, and PMS2 and MSH6 mutations limited to the MMR-deficient component; (3) dedifferentiated carcinoma with subclonal MSH2/MSH6, as well as complete loss of MLH1/PMS2, MLH1 promoter hypermethylation, and PMS2 and MSH6 mutations in both components; (4) dedifferentiated carcinoma with subclonal MSH6, and somatic and germline MSH6 mutations in both components, but with a higher allele frequency in MMR-deficient foci. Recurrences occurred in 2 patients, one consisted of the MMR-proficient component from a FIGO 1 endometrioid carcinoma, while the other was from the MSH6-mutated dedifferentiated endometrioid carcinoma. At the last follow-up (median: 44 mo), 4 patients were alive and disease-free and 2 were alive with disease. In summary, subclonal MMR loss reflects subclonal and often complex genomic and epigenetic alterations, which may have therapeutic implications and therefore must be reported when present. In addition, subclonal loss can occur in both POLE-mutated and Lynch syndrome–associated ECs.