We tested the hypothesis that chronically ischemic (IS) myocardium induces autophagy, a cellular degradation process responsible for the turnover of unnecessary or dysfunctional organelles and cytoplasmic proteins, which could protect against the consequences of further ischemia. Chronically instrumented pigs were studied with repetitive myocardial ischemia produced by one, three, or six episodes of 90 min of coronary stenosis (30% reduction in baseline coronary flow followed by reperfusion every 12 h) with the non-IS region as control. In this model, wall thickening in the IS region was chronically depressed by Ϸ37%. Using a nonbiased proteomic approach combining 2D gel electrophoresis with in-gel proteolysis, peptide mapping by MS, and sequence database searches for protein identification, we demonstrated increased expression of cathepsin D, a protein known to mediate autophagy. Additional autophagic proteins, cathepsin B, heat shock cognate protein Hsc73 (a key protein marker for chaperone-mediated autophagy), beclin 1 (a mammalian autophagy gene), and the processed form of microtubule-associated protein 1 light chain 3 (a marker for autophagosomes), were also increased. These changes, not evident after one episode, began to appear after two or three episodes and were most marked after six episodes of ischemia, when EM demonstrated autophagic vacuoles in chronically IS myocytes. Conversely, apoptosis, which was most marked after three episodes, decreased strikingly after six episodes, when autophagy had increased. Immunohistochemistry staining for cathepsin B was more intense in areas where apoptosis was absent. Thus, autophagy, triggered by ischemia, could be a homeostatic mechanism, by which apoptosis is inhibited and the deleterious effects of chronic ischemia are limited.proteomics ͉ lyposomal proteins ͉ apoptosis ͉ hibernating myocardium ͉ myocardial protection A utophagy is a cellular degradation process responsible for the turnover of unnecessary or dysfunctional organelles and cytoplasmic proteins and has been studied extensively in lower organisms such as yeast, Caenorhabditis elegans, and Drosophila (1-4). Autophagy has been suggested to be an essential function for cell homeostasis and cell defense and adaptation to an adverse environment (1, 2, 5). Autophagy is typically activated by starvation, when the cytoplasmic proteins or organelles are delivered to the lysosome and degraded (1-4). In autophagy, cytoplasmic proteins or dysfunctional organelles are sequestrated in a doublemembrane-bound vesicle, termed autophagosome, delivered to the lysosome by fusion, and then degraded. Autophagy allows the cell not only to recycle amino acids but also to remove damaged organelles, thereby eliminating oxidative stress and allowing cellular remodeling for survival (2, 6). In fact, autophagy is a cellular mechanism essential for dauer development and lifespan extension in C. elegans (1). It can also prevent accumulation of misfolded and aggregated proteins in Parkinson's, Huntington's, and Alzheimer's disease...

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Summary. Background: As hospitalized medical patients may be at risk of venous thromboembolism (VTE), evidence-based guidelines are available to help physicians assess patientsÕ risk for VTE, and to recommend prophylaxis options. The rate of appropriate thromboprophylaxis use in at-risk medical inpatients was assessed in accordance with the 6th American College of Chest Physicians (ACCP) guidelines. Methods: Hospital discharge information from the Premier Perspective TM inpatient data base from January 2002 to September 2005 was used. Included patients were 40 years old or more, with a length of hospital stay of 6 days or more, and had no contraindications for anticoagulation. The appropriateness of VTE thromboprophylaxis was determined in seven groups with acute medical conditions by comparing the daily thromboprophylaxis usage, including type of thromboprophylaxis, dosage of anticoagulant and duration of thromboprophylaxis, with the ACCP recommendations. Results: A total of 196 104 discharges from 227 hospitals met the inclusion criteria. The overall VTE thromboprophylaxis rate was 61.8%, although the appropriate thromboprophylaxis rate was only 33.9%. Of the 66.1% discharged patients who did not receive appropriate thromboprophylaxis, 38.4% received no prophylaxis, 4.7% received mechanical prophylaxis only, 6.3% received an inappropriate dosage, and 16.7% received an inappropriate prophylaxis duration based on ACCP recommendations. Conclusions: This study highlights the low rates of appropriate thromboprophylaxis in US acutecare hospitals, with two-thirds of discharged patients not receiving prophylaxis in accordance with the 6th ACCP guidelines. More effort is required to improve the use of appropriate thromboprophylaxis in accordance with the ACCP recommendations.

The sympathetic nervous system is designed to respond to stress. Adenylyl cyclase (AC) is the keystone of sympathetic transmission, yet its role in response to acute overload in the heart or in the pathogenesis of heart failure is controversial. We examined the effects of pressure overload, induced by thoracic aortic banding, in mice in which type 5 AC, a major cardiac AC isoform, was disrupted (AC5 ؊/؊ ). Left ventricular weight͞tibial length ratio (LVW͞TL) was not different between the WT and AC5 ؊/؊ at baseline and increased progressively and similarly in both groups at 1 and 3 wk after aortic banding. However, LV ejection fraction (LVEF) fell in WT at 3 wk after banding (from 70 ؎ 2.8 to 57 ؎ 3.9%, P < 0.05), and this decrease was associated with LV dilatation, indicating incipient cardiac failure. In contrast, AC5 ؊/؊ mice did not exhibit a fall in LVEF from 74 ؎ 2.2%. The number of apoptotic myocytes was similar at baseline, but it increased roughly 4-fold in WT at both 1 and 3 wk after banding, and significantly less, P < 0.05, in AC5 ؊/؊ . Importantly, the increase in apoptosis occurred before the decline in LVEF in WT. The protective mechanism seems to involve Bcl-2, which was up-regulated significantly more in AC5 ؊/؊ mice with pressure overload. Our findings suggest that limiting type 5 AC plays a protective role in response to pressure overload and the development of heart failure, potentially through limiting the incidence of myocardial apoptosis.

Thioredoxin 1 (Trx1) has redox-sensitive cysteine residues and acts as an antioxidant in cells. However, the extent of Trx1 contribution to overall antioxidant mechanisms is unknown in any organs. We generated transgenic mice with cardiac-specific overexpression of a dominant negative (DN) mutant (C32S/C35S) of Trx1 (Tg-DN-Trx1 mice), in which the activity of endogenous Trx was diminished. Markers of oxidative stress were significantly increased in hearts from Tg-DN-Trx1 mice compared with those from nontransgenic (NTg) mice. Tg-DN-Trx1 mice exhibited cardiac hypertrophy with maintained cardiac function at baseline. Intraperitoneal injection of N-2-mercaptopropionyl glycine, an antioxidant, normalized cardiac hypertrophy in Tg-DN-Trx1 mice. Thoracic aortic banding caused greater increases in myocardial oxidative stress and enhanced hypertrophy in Tg-DN-Trx1 compared with NTg mice. In contrast, transgenic mice with cardiac-specific overexpression of wild-type Trx1 did not show cardiac hypertrophy at baseline but exhibited reduced levels of hypertrophy and oxidative stress in response to pressure overload. These results demonstrate that endogenous Trx1 is an essential component of the cellular antioxidant mechanisms and plays a critical role in regulating oxidative stress in the heart in vivo. Furthermore, inhibition of endogenous Trx1 in the heart primarily stimulates hypertrophy, both under basal conditions and in response to pressure overload through redox-sensitive mechanisms.