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Post-endarterectomy platelet deposition may play an important role not only in vessel wall healing, but also in the development of progressive stenosis. Using a canine model, we investigated the effect of endothelial cell seeding on platelet deposition on endarterectomised arteries. Thirteen dogs underwent bilateral carotid intimectomy (5 cm long) and one side was seeded with an average of 2 × 10 6 viable freshly harvested endothelial cells. Blood flow was restored 20 min after seeding. On the contralateral side, a sham-seeding was performed. Deposition of 111 indium-labelled autologous platelets was studied with sequential gamma camera images 3–5h, 1, 2, 3, 4 days and 4 weeks after surgery. Platelet uptake was statistically reduced on the seeded side. Animals were killed at 4 weeks (nine dogs) and 5 weeks (four dogs) after surgery. Seven arteries for each group were found to be occluded. We conclude that endothelial cell seeding on endarterectomised arteries is feasible and reduces platelet uptake. Improvement in the efficiency of seeding and reduction of endothelial cell loss might permit clinical application of this technique.

A retrospective study of 55 patients with a benign esophageal stricture showed that in 11 patients (20%) the cause was a drug-induced lesion due to potassium chloride (3), tetracyclines (3), aspirin (2), vitamin C (1), phenytoin (1), and quinidine (1). Five of the 11 patients would have been diagnosed as having a reflux etiology of their stricture if 24-hour esophageal pH monitoring was not performed. Six patients responded to dilatation and five patients required resection or bypass. A prospective study of 18 asymptomatic volunteers showed a high incidence of esophageal lodgment of a radiolabeled medicinal capsule, with subsequent dissolution and release of the isotope. This occurred most frequently in elderly subjects and was reduced by increasing the volume of water chaser. The sites of lodgment correspond to the location of the observed strictures in the patient population. An in vitro study showed that, when the causative drugs were mixed with saliva, dissolution occurred within 60 minutes and was associated with significant changes in pH. These investigations show that drug-induced esophageal strictures are more common than previously appreciated, and can be confused with a reflux etiology. Diagnosis is suggested by a history of drug ingestion, location of the stricture, and a normal esophageal acid exposure on 24-hour pH monitoring. The severity of the esophageal injury is variable and requires dilatation to resection for therapy.

An iterative variation of the linear-element complex variable boundary element method (CVBEM) is used to generate grid points in two-dimensional simply connected spatial domains. As in many grid generation techniques, the solution of Laplace's equation is involved; however, the boundary element formulation results in a much smaller set of simultaneous equations, and once the values of the complex potential at the boundaries are fully determined, the internal grid point distribution can be altered without resolving the elliptic system. The boundary conditions implemented produce grid line orthogonality at the domain boundaries. Additionally, by using complex variables in the formulation, numerical integration is avoided. The utility of the method is demonstrated by (1) generating grid systems for several irregular geometries and (2) obtaining a numerical solution for the flow field associated with one of the geometries.

A new device has been developed that is capable of processing information from a standard Doppler signal on the relative section (RS) of arteries during the cardiac cycle. RS is a new parameter proportional to the vessel cross-section and its changes during the cardiac cycle. This parameter does not give any morphologic information on the vessel itself, but it can help in completing Dop pler analysis, providing information on vessel elasticity. RS radius (R) and ve locity (V) (traditional Doppler) signals were routinely recorded under constant-pressure conditions. The device was tested in vivo by recording the R and V tracings on 20 common femoral arteries (cf) in dogs. These measure ments were compared with the R and V tracings obtained from the largest femoral branch (fb). R and V tracings were also obtained on 20 femoral arteries after surgically induced stenosis (above, at, and below the stenosis). Both exper iments showed a significant depression of the R tracings (p < 0.01). No signifi cant difference was found between the radius value and three-projection angiography of the stenosis (p=ns). The ability of the device to determine the elasticity of the arterial wall was evaluated in vitro on 10 specimens of athero sclerotic human tibial arteries, obtained from amputated lower extremities, and on 10 samples of dog femoral arteries, and the evaluations were compared. A significant difference in the radius root mean square values was found between the 2 groups (p < 0.01). The authors conclude that this device is capable of determining a new parameter (RS) that is proportional to the cross-section of the examined artery. They have also demonstrated that RS provides useful in formation about arterial wall elasticity.