Episodes of particle ejection from the surface of the active asteroid (101955) Bennu.

Active asteroids are those that show evidence of ongoing mass loss. We report repeated instances of particle ejection from the surface of (101955) Bennu, demonstrating that it is an active asteroid. The ejection events were imaged by the OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer) spacecraft. For the three largest observed events, we estimated the ejected particle velocities and sizes, event times, source regions, and energies. We also determined the trajectories and photometric properties of several gravitationally bound particles that orbited temporarily in the Bennu environment. We consider multiple hypotheses for the mechanisms that lead to particle ejection for the largest events, including rotational disruption, electrostatic lofting, ice sublimation, phyllosilicate dehydration, meteoroid impacts, thermal stress fracturing, and secondary impacts.

Staged reduction of gastroschisis: a simple method.

Staged reduction of abdominal contents using a silastic sheet has become standard management in gastroschisis where primary closure is not possible. With the introduction of a pre-made Silastic silo coupled to a spring-loaded ring (Ben Tec, Sacramento, CA), the procedure can be done at the bedside. We present a simple technique utilizing a disposable umbilical-cord clamp that makes reduction a fast, one-physician procedure and present a preoperative step that facilitates tension-free closure of the abdominal fascia.

Congenital abdominal aortic aneurysm in the infant: case report and review of the literature.

Congenital abdominal aortic aneurysms are a distinct entity from acquired aortic aneurysms. The authors present the case of a 6-week-old boy with a 6-cm aneurysm involving the abdominal aorta and common iliac arteries. Three other cases of congenital aortic aneurysms are reviewed, and an approach to these rare patients is discussed. J Pediatr Surg 36:657-658.

Traumatic aortic incompetence associated with transection of the thoracic aorta.

A case of blunt chest trauma resulting in transection of the descending thoracic aorta and disruption of the aortic valve is presented. Successful treatment required graft repair of the aortic injury followed by aortic valve replacement.

Surgical treatment of aneurysms of the ascending aorta.

From January 1970 to April 1975, 132 patients underwent surgical repair of aneurysms of the ascending aorta at this institution, 24 of whom had acute dissections. In almost all cases the ascending aorta was replaced with a Dacron tube graft. Aortic valve replacement was performed in 100 patients and 23 patients underwent coronary artery revision or bypass. Fifteen hospital deaths occurred. Although chronic or nondissecting aneurysms may be dealt with on an elective basis, acute dissections require prompt surgical intervention. Symptomatology and radiographic findings are such that angiography may not be necessary to establish the diagnosis. Clinical evidence of aortic regurgitation in an acute dissecting aneurysm is sufficient indication for immediate operation. Improvements in surgical techniques, fabric grafts, and valve prostheses have all contributed to the successful surgical treatment of aneurysms of the ascending aorta.

Surgical treatment of left ventricular outflow tract obstruction with apicoaortic valved conduit.

From Aug. 13, 1975, through May, 1976, nine patients underwent creation of a left ventricular "vent" for relief of severe left ventricular outflow tract obstruction. A Dacron fabric graft containing a heterograft valve was used to establish a conduit from the left ventricle to the abdominal aorta. There were five male and four female patients in this group; their ages ranged from 4 to 72 years. All had valvular, subvalvular, or supravalvular aortic stenosis, and all but two had undergone previous surgical procedures for relief of the stenosis. All patients survived the operation and none are receiving anticoagulant therapy. All are asymptomatic at present and follow-up is approaching one year. Postoperative cardiac catheterization studies revealed gradients across the aortic valve to be reduced by approximately 90% and mean ventricular systolic pressures by 45%. Although this concept is not new, it has not been used widely and we believe its effectiveness warrants further application.

A new approach to repair of pulmonary branch stenosis following ascending aorta-right pulmonary artery anastomosis.

Ascending aorta-right pulmonary artery anastomosis may result in branch stenosis or occlusion of the right pulmonary artery from growth or from failure to place the anastomosis on the posterior surface of the aorta at the time of construction. Closure of the anastomosis is usually easily accomplished by simple suture through the ascending aorta. When branch stenosis is present at the site of anastomosis, reconstruction of the pulmonary artery is necessary. A new approach that facilitates repair of pulmonary branch stenosis by transecting the ascending aorta over the obstructed area has been utilized in 2 patients who required reoperation for branch stenosis following repair for tetralogy of Fallot. The method is an alternative approach to gain exposure for reconstruction of the pulmonary artery.