Rezek, Issa

Background The extent, rate, and source of endothelialization following coil embolization of saccular aneurysms remains poorly understood. We performed a whole tissue mount, dual immunohistochemical analysis of experimental aneurysms to characterize the state of endothelialization over time after platinum coil embolization. Method and material Elastase-induced rabbit aneurysms were created and treated with bare platinum coils. Samples were harvested at 4 and 8 weeks (n=6 for each). En face whole tissue mount staining with antibodies to CD31 and α-smooth muscle actin was used to identify endothelial cells and smooth muscle cells, respectively. Sytox green stain was used to demonstrate nuclear morphology for identification of inflammatory cells. The extent of endothelialization was measured in relation to the aneurysm neck–parent artery interface. Results At 4 weeks after coil embolization, very localized membranous tissue and neoendothelial cells were detected on the coil loops immediately adjacent to the parent artery–neck interface, but the remainder of the coil loops remained devoid of endothelial cells. At 8 weeks neoendothelial cells were more confluent over the coils than at 4 weeks, and extended up to 900 µm from the parent artery–neck interface. However, the surfaces of the coils farther away than this region harbored no endothelial cells. Scattered inflammatory cells, including neutrophils and monocytes, were seen on the coil surface at the neck central area, where the coil surface was bare at the 4 and 8 weeks’ follow-up. Conclusions Platinum coil embolization supports gradual but limited endothelialization, where endothelial cells migrate directly from the adjacent parent artery.

Objectives The phrase ‘Initial Clinical Experience' in a manuscript's title implies that the described technique offers promise of future clinical relevance. We assessed, using rates of subsequent citations, the actual academic relevance of such articles in comparison to articles not containing the phrase. Design We searched ISI database for articles that included the studied phrase in their titles between 1975 and 2009 and grouped the results by the related medical specialty. We excluded articles from journals with no available impact factor. For each identified article, we extracted number of included patients, citations/year, the average impact factor of the publishing journal over the last five years and the proportion of articles published in the same journal that garnered zero subsequent citations. Setting Retrospective review of a scientific database. Participants None Main outcome measures Citation rate Results Among a total of 982,127 articles published in 186 journals representing eight major publishing medical specialties, 531 (0.05%) were Initial Clinical Experience articles. Thirty percent of Initial Clinical Experience articles were never cited compared with 7% of the overall article volume ( p < 0.0001). Citations/year for Initial Clinical Experience articles were significantly lower than the median impact factor ( p < 0.0001). There was no correlation between citations and number of patients described in the Initial Clinical Experience articles ( p = 0.61). Conclusions Initial Clinical Experience articles are cited less frequently than the average, especially in Cardiovascular, Radiology and Ophthalmology journals.

Background and purpose To test the hypothesis that systemic administration of vitamin C, through its action of stimulating collagen synthesis and crosslinking, would decrease the recurrence and improve the occlusion of experimental aneurysms treated with platinum coils. Methods Experimental aneurysms were created in female rabbits and were embolized with platinum coils (>30% packing density). The animals were divided into three groups: group 1 (n=6) rabbits served as controls, group 2 (n=5) rabbits were fed with a vitamin C supplemented feed and group 3 (n=8) rabbits were medicated with vitamin C pills. Digital subtraction angiography was used to evaluate stability after embolization. Subjects were euthanized at 12 weeks after coil implantation, and serum vitamin C levels were then measured. Histological samples were examined with a grading system (range 0–12) based on the neck and dome features. Masson Trichrome staining was used to evaluate collagen deposition. Parametric data were analyzed with one way analysis of variance and non-parametric data were examined using a Kruskal–Wallis test. Results There were no significant differences between groups in mean aneurysm size. Mean serum vitamin C concentration was significantly higher in group 3 and group 2 compared with group 1, while vitamin C levels between group 2 and group 3 were statistically comparable. Coil compaction was noted in one of six subjects in group 1 and in three of eight subjects in group 3. All of the remaining aneurysms in the test and control groups showed stable occlusion. There were no significant differences in histological scores or collagen deposition among groups. Conclusions Vitamin C supplementation following platinum coil embolization does not demonstrate improvement of long term occlusion rates of aneurysms.