Fluid-structure interaction in layered aortic arch aneurysm model: assessing the combined influence of arch aneurysm and wall stiffness.

The patients with aortic aneurysm, especially aortic arch aneurysm, are prone to have aortic dissection. For investigation of the effect of aneurysm and wall stiffness on wall stress distribution, both the nonaneurysm arch model and the aneurysm arch model are constructed. The fluid structure interaction in the arch model of aorta was implemented. The results show the stresses are much higher at inflection points in aneurysm model than in nonaneurysm model, and the stresses at media in stiffened wall are higher than in unstiffened wall. The high composite stress is located at inflection points and is much higher in aneurysm model. The arch aneurysm and wall stiffening are important determinants of peak wall stress in aortic wall.

Development of vasa vasorum in the arterially implanted autovein bypass graft and its anastomosis in the dog.

Using stereomicroscopy, light microscopy, and scanning electron microscopy, we investigated the development of vasa vasorum in the proliferated neointima of the autovein graft and its anastomoses implanted in the canine femoral artery against a background of poor distal runoff. In the stereomicroscopic examination, a microfil silicone rubber compound (MF) was injected transluminally or via perivascular vasa, and the vascular specimen was prepared for clearing by immersion in a methyl-salicylate solution. Vessel interstices filled with MF were found adjacent to the suture materials within 5 days of grafting. Fourteen days after implantation, luminally originating vasa vasorum were often visible in the neointima along the suture line and distributed into the media and adventitia connecting to the original vasa vasorum. At 6 months or more after grafting, many orifices of luminally originating vasa vasorum were seen along the suture line of both proximal end-to-end and distal end-to-side anastomoses and distributed into the thickened neointima forming a vasa network when the neointima had proliferated to over 250 microm in depth. On the other hand, some clefts filled with MF were found in mural thrombi deposited on the vascular sinus of the graft within 5 days, and these appeared to be one of the sources of luminally originating vasa vasorum on the graft distant from the suture line. Moreover, the development of numerous vasa vasorum was constantly demonstrated in the neointima when it had proliferated to over 250 microm in depth.

Effects of dithiocarbamates and cadmium on the enzymatic activities in liver, kidney and blood of mice.

The effects of N-benzyl-D-glucamine dithiocarbamate (BGD), diethyldithiocarbamate (DDTC), and N-p-hydroxymethylbenzyl-D-glucamine dithiocarbamate (HBGD) on the enzymatic activities in mice were studied. The mice were given i.v. injections of these chelating agents (1 mmol/kg) and 3 h later the activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyltranspeptidase (gamma-GTP), alkaline phosphatase (ALP), leucine aminopeptidase (LAP), and cholinesterase (ChE) in the liver, kidney, and blood were determined. These enzymatic activities were little changed by treatment with these chelating agents. Cadmium (Cd) administration markedly decreased the activities of AST and ALT in the liver and kidney and greatly increased these enzymatic activities in blood. The changes in the enzymatic activities by treatment with Cd were prevented by injection of BGD (1 mmol/kg). These results indicate that BGD, DDTC, and HBGD were not toxic to the liver or kidney of mice and that BGD treatment protected against the acute hepatic and renal toxicity induced by Cd.