Force fluctuations in bead packs.

Experimental observations and numerical simulations of the large force inhomogeneities present in stationary bead packs are presented. Forces much larger than the mean occurred but were exponentially rare. An exactly soluble model reproduced many aspects of the experiments and simulations. In this model, the fluctuations in the force distribution arise because of variations in the contact angles and the constraints imposed by the force balance on each bead in the pile.

Use of profound hypothermia and circulatory arrest in complex intra-cardiac repair in adults.

Profound hypothermia and circulatory arrest is a well worked out technique for total repair of congenital defects in infants. Recently, it has been popularized for the repair of aneurysms of the transverse aortic arch. We have applied this technique of profound hypothermia and circulatory arrest in three other adult patients in whom conventional techniques would not allow safe and adequate complete repair of acquired intra-cardiac defects. The first patient, a 76-year-old female, had a large chronic ascending aortic aneurysm involving the aortic valve, as well as the innominate and left common carotid arteries. Resuspension of the aortic valve, resection of the ascending aneurysm, and reconstruction of the ascending and transverse aorta were performed under profound circulatory arrest. In addition, multi-dose hypothermic blood K+ cardioplegia was utilized to protect the myocardium. The second patient underwent valve replacement during a period of circulatory arrest because of extensive calcification of the entire ascending aorta and transverse aortic arch. Arrest time was 56 minutes. The third patient was a 54-year-old female and had a large patent ductus arteriosus with a 3:1 left-to-right shunt as well as significant aortic and mitral valve disease. The ductus was closed through an incision in the pulmonary artery during a 13-minute period of profound hypothermia and circulatory arrest. Aortic valve replacement and mitral repair were also performed at the same time, utilizing conventional techniques. All three patients recovered uneventfully with no evidence of any significant neurologic defect. Long-term follow-up has shown improvement in functional classification in all patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Periodic acid-Schiff-negative granulomatous lymphadenopathy in patients with Whipple's disease. Localization of the Whipple bacillus to noncaseating granulomas by electron microscopy.

The diagnosis of Whipple's disease in a 58-year-old man was based on the finding of periodic acid-Schiff (PAS)-positive foamy macrophages on duodenal biopsy and demonstration of the typical bacilliform bodies by electron microscopy. The patient also had generalized peripheral lymphadenopathy with lymph node biopsy showing PAS-negative noncaseating granulomas. Electron microscopic examination of the lymph node specimen demonstrated a small number of typical bacilliform bodies with localization specifically to the granulomas in the lymph node. This finding of bacilliform bodies within PAS-negative noncaseating granulomas has not been reported previously. Localization of the Whipple bacillus specifically to noncaseating granulomas suggests that some patients with the disease may manifest a delayed hypersensitivity reaction to the bacillus.