Age- and Hypertension-Associated Protein Aggregates in Mouse Heart Have Similar Proteomic Profiles.

Neurodegenerative diseases are largely defined by protein aggregates in affected tissues. Aggregates contain some shared components as well as proteins thought to be specific for each disease. Aggregation has not previously been reported in the normal, aging heart or the hypertensive heart. Detergent-insoluble protein aggregates were isolated from mouse heart and characterized on 2-dimensional gels. Their levels increased markedly and significantly with aging and after sustained angiotensin II-induced hypertension. Of the aggregate components identified by high-resolution proteomics, half changed in abundance with age (392/787) or with sustained hypertension (459/824), whereas 30% (273/901) changed concordantly in both, each P<0.05. One fifth of these proteins were previously associated with age-progressive neurodegenerative or cardiovascular diseases, or both (eg, ApoE, ApoJ, ApoAIV, clusterin, complement C3, and others involved in stress-response and protein-homeostasis pathways). Because fibrosis is a characteristic of both aged and hypertensive hearts, we posited that aging of fibroblasts may contribute to the aggregates observed in cardiac tissue. Indeed, as cardiac myofibroblasts "senesced" (approached their replicative limit) in vitro, they accrued aggregates with many of the same constituent proteins observed in vivo during natural aging or sustained hypertension. In summary, we have shown for the first time that compact (detergent-insoluble) protein aggregates accumulate during natural aging, chronic hypertension, and in vitro myofibroblast senescence, sharing many common proteins. Thus, aggregates that arise from disparate causes (aging, hypertension, and replicative senescence) may have common underlying mechanisms of accrual.

ST-elevation myocardial infarction as a complication of retrograde chronic total occlusion recanalization.

With the advent of new tools and techniques including the retrograde approach, success rates for recanalization of chronic total occlusion (CTO) have improved. Numerous cardiac and extracardiac complications during retrograde CTO recanalization have been described. To date the development of ST-segment elevation myocardial infarction (STEMI) with retrograde recanalization as a result of atheroembolization has not been reported. We report such a case following retrograde recanalization of a totally occluded right coronary artery.

Complete arterial coronary bypass revascularization with single aorto-ostial anastomosis and long-term outcome.

Coronary reoperations continue to play an important role in the practice of coronary artery bypass grafting (CABG). Apart from having a sicker patient subgroup, reoperation poses an increasingly more complex and technically demanding surgery to perform. The superior patency of the left internal mammary artery (LIMA) has prompted increased interest in using arterial conduits for coronary bypass. However in situations where LIMA to left anterior descending (LAD) graft can not be done successfully, it remains a problem. We present a case of repeat three vessel coronary bypass surgery where three free arterial grafts were used with single anastomosis to ascending aorta as an alternative because of compromised length of LIMA and radial grafts.

Genomics of cardiac remodeling in angiotensin II-treated wild-type and LOX-1-deficient mice.

We studied the gene expression profile during cardiac hypertrophy induced by angiotensin (ANG) II in wild-type mice and the influence of LOX-1 deletion on the gene expression profile. Wild-type and LOX-1 knockout mice were given saline or ANG II infusion for 4 wk. The saline-treated LOX-1 knockout mice showed upregulation of several genes including Ddx3y and Eif2s3y. ANG II infusion enhanced expression of genes known to be associated with cardiac remodeling, such as Agt, Ace, Timp4, Fstl, and Tnfrst12a, as well as oxidant stress-related genes Gnaq, Sos1, and Rac1. Some other strongly upregulated genes identified in this study have not been previously associated with LOX-1 deletion and/or hypertension. To confirm these observations with ANG II infusion and LOX-1 deletion, cultured HL-1 mouse cardiomyocytes were exposed to ANG II or transfected with pCI-neo/LOX-1, which resulted in severalfold increase in reactive oxygen species generation, upregulation of ANG II type 1 (AT(1)) receptor, and cardiomyocyte growth. Quantitative PCR analysis of these treated cardiomyocytes confirmed upregulation of many of the genes identified in the in vivo study. This study provides the first set of data on the gene expression profiling of cardiac tissue treated with ANG II and expands on the important role of LOX-1 in cardiac response to ANG II.

Expression of Nkx2.5 in wild type, cardiac mutant, and thyroxine-induced metamorphosed hearts of the Mexican axolotl.

Nkx2.5, a homeodomain-containing transcription factor, is known to be necessary for normal heart development in vertebrates. It is one of the earliest lineage-restricted genes expressed in cardiovascular progenitor cells and knowledge of its expression patterns has important therapeutic implications for damaged cardiomyocytes. Mexican axolotl is a unique system to study heart development for two reasons: the presence of a mutant phenotype lacking organized myofibrils due to sarcomeric tropomyosin deficiency and the ability to induce metamorphosis by administration of exogenous thyroid hormone. In this study, we cloned and sequenced the as yet uncharacterized Nkx2.5 cDNA from normal and cardiac mutant axolotl heart RNA. Comparison of cDNA sequences of Nkx2.5 from normal and mutant axolotl hearts did not show differences suggesting that loss of function mutation in Nkx2.5 is not responsible for the mutant phenotype. However, quantitative studies show higher expression of Nkx2.5 in mutant hearts raising the possibility that increased expression of Nkx2.5 may contribute to the mutant phenotype. We also evaluated quantitative changes in expression of Nkx2.5 in axolotl hearts during embryonic and postembryonic heart development induced by exogenous thyroid hormone. There is an apparent increase in Nkx2.5 transcript levels in metamorphosed hearts.

Effect of statins on fasting plasma glucose in diabetic and nondiabetic patients.

BACKGROUND: The 3-hydroxy-3-methylglutaryl-CoA reductase inhibitors (statins) reduce serum cholesterol level and cardiovascular morbidity and mortality. However, the effect of statins on glucose metabolism is unclear. Some studies have suggested that statins may cause hyperglycemia by increasing calcium concentration in the islet cells leading to decrease in insulin release or by decreasing GLUT 4-mediated peripheral glucose uptake. METHODS: We analyzed the data in 345,417 patients (mean age 61 +/- 15 years, 94% males, 6% diabetic, 20% statin users) from the Veterans Affairs VISN 16 database. We studied change in fasting plasma glucose (FPG) in this population over a mean time of 2 years between the first available measurement and the last measurement form the most recent recorded visit. Data were limited to patients who had 2 FPG measurements. Diagnosis of diabetes had to be present before the first FPG measurement. RESULTS: Among patients without diabetes, FPG increased with statin use from 98 mg/dL to 105 mg/dL, and among nonstatin users, FPG increased from 97 mg/dL to 101 mg/dL (increase in FPG with statin use P < 0.0001). Among patients with diabetes, FPG increased with statin use from 102 mg/dL to 141 mg/dL, and among nonstatin users, FPG increased from 100 mg/dL to 129 mg/dL (increase in FPG with statin use; P < 0.0001). After adjustment for age and use of aspirin, beta-blockers, and angiotensin-converting enzyme inhibitors, the change in FPG in nondiabetic statin users was 7 mg/dL (vs 5 mg/dL in nonstatin users, P < 0.0001) and for diabetic statin users it was 39 mg/dL (vs 32 in nonstatin users, P < 0.0001). CONCLUSIONS: Statin use is associated with a rise of FPG in patients with and without diabetes. This relationship between statin use and rise in FPG is independent of age and use of aspirin, beta-blockers, and angiotensin-converting enzyme inhibitors.

LOX-1 dependent overexpression of immunoglobulins in cardiomyocytes in response to angiotensin II.

LOX-1, a cell surface lectin-like receptor, is upregulated by oxidized low-density lipoprotein (ox-LDL) and angiotensin II (Ang II), and plays an important role in host defense. The specific C-type lectin domain on LOX-1 is essential for ox-LDL binding and internalization, generation of oxidant species and eliciting immune response. Here, we show that LOX-1 deletion alters genes that relate to immune response. Microarray (and qPCR) analysis of cardiac tissues showed downregulated expression of several immunoglobulins (Igk-V8, Igk-C, Igh-6, Igj, Ighg, Igh, and Igl-V1) in the LOX-1 knockout (KO) mice [p<0.05 vs. the wild-type (WT) mice]. The expression of these immunoglobulins was upregulated several-fold in the LOX-1 KO mice hearts when these mice were infused with Ang II (p<0.05, vs. WT mice). Importantly, cultured mouse HL-1 cardiomyocytes expressed these immunoglobulins, and pretreatment of cardiomyocytes with a specific anti-LOX-1 antibody enhanced the generation of immunoglobulins upon subsequent exposure to Ang II. These observations mirrored the data obtained from WT and LOX-1 KO mice hearts in the resting state and following Ang II infusion. This study provides first set of data on immunoglobulin expression in cardiac tissues of WT and LOX-1 KO mice and in cultured HL-1 cardiomyocytes, and demonstrates that LOX-1 inactivation leads to upregulation of immunoglobulins in cardiomyocytes upon challenge with Ang II.

A reduction of tropomyosin limits development of sarcomeric structures in cardiac mutant hearts of the Mexican axolotl.

The cardiac lethal mutation in Mexican axolotl (Ambystoma mexicanum) results in a lack of contractions in the ventricle of mutant embryos. Previous studies have demonstrated that tropomyosin, a component of thin filaments, is greatly reduced in mutant hearts lacking myofibril organization. Confocal microscopy was used to examine the structure and comparative amount of tropomyosin at heartbeat initiation and at a later stage. The formation of functional sarcomeres coincided with contractions in normal hearts at stage 35. A-bands and I-bands were formed at stage 35 and did not change at stage 39. The widening of Z-bodies into z-lines was the main developmental difference between stage 35 and 39 normal hearts. Relative to normal hearts, a reduction of sarcomeric protein levels in mutant hearts at stage 35 was found, and a greater reduction occurred at later stages. The lower level of tropomyosin limited the areas where organized myofibrils formed in the mutant. The areas that had tropomyosin staining also had staining for alpha-actinin and myosin. Early myofibrils formed in these areas but the A-bands and I-bands were shorter than normal. At a later stage in the mutant, A-bands and I-bands remained shorter and importantly the Z-bodies also did not form wider z-lines.