Publications

PURPOSE

We performed a systematic review to define the relative and absolute risk of clinically relevant adverse events with the antiplatelet agents, aspirin and clopidogrel.

MATERIALS AND METHODS

Databases were searched for randomized controlled trials of low-dose aspirin (75-325 mg/day) or clopidogrel administered for cardiovascular prophylaxis. Relative risks (RR) were determined by meta-analysis of 22 trials for aspirin versus placebo and from single studies for aspirin versus clopidogrel, aspirin versus aspirin/clopidogrel, and clopidogrel versus aspirin/clopidogrel. Absolute risk increase was calculated by multiplying RR increase by the pooled weighted incidence of the control.

RESULTS

Aspirin increased the risk of major bleeding (RR=1.71; 95% confidence interval [CI], 1.41-2.08), major gastrointestinal (GI) bleeding (RR=2.07; 95% CI, 1.61-2.66), and intracranial bleeding (RR=1.65; 95% CI, 1.06-5.99) versus placebo. No difference between 75-162.5 mg/day and >162.5-325 mg/day aspirin versus placebo was seen. The absolute annual increases attributable to aspirin were major bleeding: 0.13% (95% CI, 0.08-0.20); major GI bleeding: 0.12% (95% CI, 0.07-0.19), intracranial bleeding: 0.03% (95% CI, 0.01-0.08). No study compared clopidogrel with placebo. One study showed increased major GI bleeding (but not non-GI bleeding endpoints) with aspirin versus clopidogrel (RR=1.45; 95% CI, 1.00-2.10). The absolute annual increase was 0.12% (95% CI, 0.00-0.28).

CONCLUSIONS

Low-dose aspirin increases the risk of major bleeding by approximately 70%, but the absolute increase is modest: 769 patients (95% CI, 500-1250) need to be treated with aspirin to cause one additional major bleeding episode annually. Compared with clopidogrel, aspirin increases the risk of GI bleeding but not other bleeding; however, 883 patients (95% CI, 357-infinity) would need to be treated with clopidogrel versus aspirin to prevent one major GI bleeding episode annually at a cost of over 1 million dollars.

In patients requiring mechanical ventilation for acute lung injury or acute respiratory distress syndrome (ARDS), tidal volume reduction decreases mortality, but the mechanisms of the protective effect have not been fully explored. To test the hypothesis that alveolar macrophage activation is an early and critical event in the initiation of ventilator-induced lung injury (VILI), rats were ventilated with high tidal volume (HV(T)) for 10 min to 4 h. Alveolar macrophage counts in bronchoalveolar lavage (BAL) fluid decreased 45% by 20 min of HV(T) (P < 0.05) consistent with activation-associated adhesion. Depletion of alveolar macrophages in vivo with liposomal clodronate significantly decreased permeability and pulmonary edema following 4 h of HV(T) (P < 0.05). BAL fluid from rats exposed to 20 min of HV(T) increased nitric oxide synthase activity nearly threefold in naïve primary alveolar macrophages (P < 0.05) indicating that soluble factors present in the air spaces contribute to macrophage activation in VILI. Media from cocultures of alveolar epithelial cell monolayers and alveolar macrophages exposed to 30 min of stretch in vitro also significantly increased nitrite production in naïve macrophages (P < 0.05), but media from stretched alveolar epithelial cells or primary alveolar macrophages alone did not, suggesting alveolar epithelial cell-macrophage interaction was required for the subsequent macrophage activation observed. These data demonstrate that injurious mechanical ventilation rapidly activates alveolar macrophages and that alveolar macrophages play an important role in the initial pathogenesis of VILI.

Primary canine oral mucosal epithelial cells were cultured on temperature-responsive dishes and cell culture inserts to fabricate transplantable epithelial cell sheets. When 3T3 feeder layers and fetal bovine serum were eliminated from dish culture, the harvested cell sheets became significantly more fragile. In contrast, when epithelial cells were cultured on inserts having submicron-scale pores, cell sheet fragility was eliminated. Keratin expression profiles showed no differences among the harvested cell sheets, but the expression of p63, a putative stem/progenitor marker, was strongly dependent on the presence of 3T3 feeder layers and serum. These results suggest that the maintenance of stem/progenitor cells is influenced by the apical/basal supply of nutrients as well as culture supplements.

BACKGROUND

The effect of raloxifene, a selective estrogen-receptor modulator, on coronary heart disease (CHD) and breast cancer is not established.

METHODS

We randomly assigned 10,101 postmenopausal women (mean age, 67.5 years) with CHD or multiple risk factors for CHD to 60 mg of raloxifene daily or placebo and followed them for a median of 5.6 years. The two primary outcomes were coronary events (i.e., death from coronary causes, myocardial infarction, or hospitalization for an acute coronary syndrome) and invasive breast cancer.

RESULTS

As compared with placebo, raloxifene had no significant effect on the risk of primary coronary events (533 vs. 553 events; hazard ratio, 0.95; 95 percent confidence interval, 0.84 to 1.07), and it reduced the risk of invasive breast cancer (40 vs. 70 events; hazard ratio, 0.56; 95 percent confidence interval, 0.38 to 0.83; absolute risk reduction, 1.2 invasive breast cancers per 1000 women treated for one year); the benefit was primarily due to a reduced risk of estrogen-receptor-positive invasive breast cancers. There was no significant difference in the rates of death from any cause or total stroke according to group assignment, but raloxifene was associated with an increased risk of fatal stroke (59 vs. 39 events; hazard ratio, 1.49; 95 percent confidence interval, 1.00 to 2.24; absolute risk increase, 0.7 per 1000 woman-years) and venous thromboembolism (103 vs. 71 events; hazard ratio, 1.44; 95 percent confidence interval, 1.06 to 1.95; absolute risk increase, 1.2 per 1000 woman-years). Raloxifene reduced the risk of clinical vertebral fractures (64 vs. 97 events; hazard ratio, 0.65; 95 percent confidence interval, 0.47 to 0.89; absolute risk reduction, 1.3 per 1000).

CONCLUSIONS

Raloxifene did not significantly affect the risk of CHD. The benefits of raloxifene in reducing the risks of invasive breast cancer and vertebral fracture should be weighed against the increased risks of venous thromboembolism and fatal stroke. (ClinicalTrials.gov number, NCT00190593 [ClinicalTrials.gov].).

BACKGROUND

Tissue engineering approaches involving the direct transplantation of cardiac patches have received significant attention as alternative methods for the treatment of damaged hearts. In contrast, we used cardiomyocyte sheets harvested from temperature-responsive culture dishes to create pulsatile myocardial tubes and examined their in vivo function and survival.

METHODS AND RESULTS

Neonatal rat cardiomyocyte sheets were sequentially wrapped around a resected adult rat thoracic aorta and transplanted in place of the abdominal aorta of athymic rats (n=17). Four weeks after transplantation, the myocardial tubes demonstrated spontaneous and synchronous pulsations independent of the host heartbeat. Independent graft pressures with a magnitude of 5.9+/-1.7 mm Hg due to their independent pulsations were also observed (n=4). Additionally, histological examination and transmission electron microscopy indicated that the beating tubes were composed of cardiac tissues that resemble the native heart. Finally, when myocardial tubes used for aortic replacement were compared with grafts implanted in the abdominal cavity (n=7), we observed significantly increased tissue thickness, as well as expression of brain natriuretic peptide, myosin heavy chain-alpha, and myosin heavy chain-beta.

CONCLUSIONS

Functional myocardial tubes that have the potential for circulatory support can be created with cell sheet engineering. These results also suggest that pulsation due to host blood flow within the lumen of the myocardial tubes has a profound effect on stimulating cardiomyocyte hypertrophy and growth. These results demonstrate a novel approach for the future development of engineered cardiac tissues with the ability for independent cardiac assistance.