Correction: A Bone Metastasis Nude Mouse Model Created by Ultrasound Guided Intracardiac Injection of Breast Cancer Cells: the Micro-CT, MRI and Bioluminescence Imaging Analysis.

[This corrects the article on p. 57 in vol. 64.].

What is the real practice of exercise echocardiographic testing in asymptomatic patients with severe aortic stenosis?

BACKGROUND: Although exercise testing has been suggested to help predict clinical outcome, limited data are available to guide how exercise Doppler echocardiography (ECG) can be used clinically in asymptomatic patients with aortic stenosis (AS). The aim of this study was to assess the clinical value of exercise echocardiographic testing in asymptomatic patients with severe AS. METHODS: Symptom-limited treadmill exercise testing using the modified Bruce protocol was performed in 31 asymptomatic patients (mean age (62 ± 11) years) with severe AS (aortic valve area <1 cm(2), peak aortic velocity (AV Vmax) >4 m/sec, or a mean transaortic pressure gradient (AV mean PG) >40 mmHg (1 mmHg = 0.133 kPa)) with normal left ventricular (LV) systolic function (LV ejection fraction (EF) >50%). Clinical symptoms, vital signs, ECG, and Doppler hemodynamics were obtained during and/or immediately after exercise. RESULTS: Aortic valve replacement (AVR) was performed in 18 patients during follow-up. The patients who had AVR exhibited higher baseline AV mean PG (51 (35-84) vs. 44 (25.2-57.0) mmHg; P = 0.031). There were no significant differences between the AVR group and non-AVR group including exercise duration (7.47 (2.32-11.59) vs. 7.25 (4.06-10.52) minutes, P = 0.917), exercise capacity (10.1 (4.6-12.8) vs. 10.1 (7.0-12.8) metabolic equivalents, P = 0.675), and an increment in AV mean PG by exercise (18.5 (3.2-48.0) vs. 12.6 (4.4-32.1) mmHg, P = 0.366). Univariate regression analysis revealed that independent determinant of AVR was the baseline AV mean PG (P = 0.031). CONCLUSIONS: Although additional value of exercise ECG was demonstrated, baseline transaortic mean pressure gradient is the major determinant of AVR. Further large-scale prospective studies are required to determine whether surgery should be recommended in the presence of an abnormal exercise ECG in asymptomatic severe AS.

Prolonged expression of senescence markers in mice exposed to gamma-irradiation.

Although ionizing radiation is known to induce cellular senescence in vitro and in vivo, its long-term in vivo effects are not well defined. In this study, we examined the prolonged expression of senescence markers in mice irradiated with single or fractionated doses. C57BL/6 female mice were exposed to 5 Gy of γ-rays in single or 5, 10, 25 fractions. At 2, 4, and 6 months after irradiation, senescence markers including mitochondrial DNA (mtDNA) common deletion, p21, and senescence-associated ß-galactosidase (SA ß-gal) were monitored in the lung, liver, and kidney. Increases of mtDNA deletion were detected in the lung, liver, and kidney of irradiated groups. p21 expression and SA ß-gal staining were also increased in the irradiated groups compared to the non irradiated control group. Increases of senescence markers persisted up to 6 months after irradiation. Additionally, the extent of mtDNA deletion and the numbers of SA ß-gal positive cells were greater as the number of radiation fractions increased. In conclusion, our results showed that ionizing radiation, especially that delivered in fractions, can cause the persistent upregulation of senescence marker expression in vivo. This should be considered when dealing with chronic normal tissue injuries caused by radiation therapy or radiation accidents.