Early satellite cell communication creates a permissive environment for long-term muscle growth

Using in vivo muscle stem cell (satellite cell)-specific extracellular vesicle (EV) tracking, satellite cell depletion, in vitro cell culture, and single-cell RNA sequencing, we show satellite cells communicate with other cells in skeletal muscle during mechanical overload. Early satellite cell EV communication primes the muscle milieu for proper long-term extracellular matrix (ECM) deposition and is sufficient to support sustained hypertrophy in adult mice, even in the absence of fusion to muscle fibers. Satellite cells modulate chemokine gene expression across cell types within the first few days of loading, and EV delivery of miR 206 to fibrogenic cells represses Wisp1 expression required for appropriate ECM remodeling. Late-stage communication from myogenic cells during loading is widespread but may be targeted toward endothelial cells. Satellite cells coordinate adaptation by influencing the phenotype of recipient cells, which extends our understanding of their role in muscle adaptation beyond regeneration and myonuclear donation

Adjacent thoracic lymph node metastases originating from two separate primary cancers: case report

Reported is an unusual case of adjacent thoracic lymph nodes demonstrating metastases from two different primary malignancies. A 51 year-old woman with a previous history of bilateral breast cancer underwent a radical gastro-oesophagectomy for adenocarcinoma of the lower third of the oesophagus. The resection specimen demonstrated breast and oesophageal metastases in adjacent thoracic lymph nodes. Mechanisms for this phenomenon, including the known local immune suppression on lymphoid cells by oesophageal carcinoma cells, are discussed

A naturalist at the zoo /

Mode of access: Internet

Changes in temperature affect the risk of abdominal aortic aneurysm rupture

Background: There is a well-established link between exposure to hot and cold temperatures and an increased risk of cardiovascular hospitalization or death. There is also contrasting evidence of a seasonal increase in aortic ruptures related to atmospheric pressure, but an association with environmental temperature has never been formally modelled. Methods: Using a prospective database, we identified 295 patients who were operated in a single centre for ruptured abdominal aortic aneurysm in south-east Queensland between 1990 and 2010. We matched patients to their nearest weather station to estimate their exposure to temperature and air pressure in the days leading up to their rupture. We used the case-crossover method to estimate the risks of temperature, which we allowed to be non-linear (increased risks at high and low temperatures) and delayed by up to 25 days. Results: There was an immediate increase in risk after exposure to cold, and a delayed risk after exposure to heat. An increased risk after exposure to high pressures disappeared after adjusting for temperature. At a mean temperature of 19°C (66°F), the odds ratio for rupture was 1.73 (95% confidence interval: 1.09, 2.76) compared with the reference temperature of 24°C. Conclusion: This is the first study to demonstrate an association between temperature and risk of aortic aneurysm rupture in the Southern Hemisphere. The physiological changes caused by thermoregulation may be a trigger for those people with a fragile aneurysm