Pinhole Descending Aortic Rupture with Systemic Sclerosis and Dermatomyositis: A Case Report.

Thoracic descending aortic perforation with overlap syndrome (systemic sclerosis and dermatomyositis) is a rare, unreported vascular pathology. We describe the case of a 75-year-old woman who presented with chest tightness, back pain, and dyspnea. Computed tomography revealed a pinhole rupture in the descending aorta.

Electromyography of Flight Muscles in Free-Flying Chestnut Tiger Butterfly, .

The chestnut tiger butterfly, , can undertake long-distance migrations. They flap their wings for power flight and hold the wings for gliding; such repertoires of wing movements may be the key to explaining their excellent flight abilities. Measuring flight muscle activity using the electromyogram (EMG) is the first step toward understanding the neuromuscular mechanism of active flight control.

Mechanism of Nucleotide-Dependent Allosteric Regulation in Aspartate Transcarbamoylase.

Discovered nearly 70 years ago, the allosteric regulation of aspartate transcarbamoylase (ATCase) is discussed in every biochemistry textbook. ATCase catalyzes the first step in pyrimidine biosynthesis. Despite extensive research, the mechanism by which this enzyme is regulated by pyrimidine and purine nucleotides has remained elusive.