Initial experience with the Penumbra Stroke System for recanalization of large vessel occlusions in acute ischemic stroke

Introduction  

The Penumbra system is a newly approved mechanical device for the treatment of acute stroke designed for better and faster recanalization. We describe our initial experience with the use of this device.     

Evaluation of the role of location and distance in recruitment in respondent-driven sampling

Background

The purpose of the project was to delineate a series of contiguous neighbourhood-based "Data Zones" within the Region of Peel (Ontario) for the purpose of health data analysis and dissemination. Zones were to be built on Census Tracts (N = 205) and obey a series of requirements defined by the Region of Peel. This paper explores a method that combines statistical analysis with ground-truthing, consultation, and the use of a decision tree.

Data

Census Tract data for Peel were derived from the 2006 Canadian Census Master file.

Methods

Following correlation analysis to reduce the data set, Principal Component Analysis was applied to the data set to reduce the complexity and derive an index. The Getis-Ord Gi*statistic was then applied to look for statistically significant clusters of like Census Tracts. A detailed decision tree for the amalgamation of remaining zones and ground-truthing with Peel staff verified the resulting zones.

Results

A total of 15 Data Zones that are similar with respect to socioeconomic and sociodemographic attributes and that met criteria defined by Peel were derived for the region.

Conclusion

The approach used in this analysis, which was bolstered by a series of checks and balances throughout the process, gives statistical validity to the defined zones and resulted in a robust series of Data Zones for use by Peel Public Health. We conclude by offering insight into alternative uses of the methodology, and limitations.     

The role of Bcl-2 expression in EGF inhibition of TNF-alpha/IFN-gamma-induced villous trophoblast apoptosis.

The inflammatory cytokines tumour necrosis factor alpha (TNF-alpha) and immune interferon gamma (IFN-gamma) stimulate villous cytotrophoblast apoptosis while epidermal growth factor (EGF) protects. We hypothesize that TNF-alpha, IFN-gamma and EGF regulate apoptosis in part by modulating cellular expression levels of the anti-death gene bcl-2. While Bcl-2 is reported to be strongly expressed in villous syncytiotrophoblasts, it is not known whether the protein is expressed in cultured villous cytotrophoblasts (CT) and, if so, whether it is functional. We show by Northern blot analysis that bcl-2 mRNA is expressed in cultured CT and by immunoblot analysis that the protein is strongly expressed in highly purified first trimester and term villous cytotrophoblasts. The expression levels of Bcl-2 protein were the same in first trimester and term cytotrophoblasts. Culture with TNF-alpha/IFN-gamma and EGF did not alter expression of either Bcl-2 protein or of the pro-apoptotic Bcl-2 family member Bak. Double label flow cytometric analysis that measured apoptosis and Bcl-2 content simultaneously showed that cells expressing low levels of Bcl-2 underwent TNF-alpha/IFN-gamma-induced apoptosis at a higher frequency than cells expressing lower levels. We conclude that Bcl-2 is expressed in cytotrophoblasts, that its expression is constitutive and that modulation of its expression levels does not mediate cytokine and growth factor regulation of apoptosis in these cells.     

Acute ischemic stroke: accuracy of diffusion-weighted MR imaging--effects of b value and cerebrospinal fluid suppression

PURPOSE: To prospectively determine which diffusion-weighted magnetic resonance (MR) imaging technique (ie, conventional diffusion-weighted MR imaging [b = 1000 or 1500 sec/mm2] or fluid-inversion prepared diffusion [FLIPD] MR imaging [b = 1500 sec/mm2]) is most accurate in depicting acute ischemic stroke at 3 T. MATERIALS AND METHODS: The Health Research Ethics Board approved this study; written informed consent was provided by all participants or their surrogate. Diffusion-weighted MR imaging was performed in 75 consecutive patients (43 men, 32 women; mean age, 64.0 years) with acute ischemic stroke. Two experienced neuroradiologists determined the presence of hyperacute stroke lesions at diffusion-weighted MR imaging by locating areas of hyperintensity that corresponded to regions with a decreased diffusion coefficient. These findings were used as the reference standard. Four raters who were blinded to patient history assessed all images and apparent diffusion coefficient maps for the presence of changes that were consistent with acute ischemic stroke. Accuracy, sensitivity, specificity, negative predictive value, positive predictive value, and inter- and intrarater reliability scores were calculated for each technique. RESULTS: Specificity, positive predictive value, and accuracy were not significantly different among the techniques. FLIPD MR images obtained with a b value of 1500 sec/mm2 had decreased sensitivity for acute ischemic stroke (mean, 61.8%; 95% confidence interval [CI]: 55.4%, 67.9%) compared with conventional diffusion-weighted MR images obtained with a b value of either 1000 sec/mm2 (mean, 82.5%; 95% CI: 77.1%, 87.0%) or 1500 sec/mm2 (mean, 84.5%; 95% CI: 79.3%, 88.9%). FLIPD MR images also had decreased negative predictive value (mean, 96.5%; 95% CI: 95.7%, 97.2%) compared with conventional diffusion-weighted MR images obtained with a b value of either 1000 sec/mm2 (mean, 98.4%; 95% CI: 97.8%, 98.8%) or 1500 sec/mm2 (mean, 98.6%; 95% CI: 98.1%, 99.0%). Intra- and interrater reliability scores were generally excellent for all three techniques. CONCLUSION: FLIPD MR images obtained with a b value of 1500 sec/mm2 are less suitable for the detection of acute ischemic stroke owing to a decreased sensitivity and negative predictive value. The performance of the two conventional diffusion-weighted MR imaging techniques (b = 1000 and 1500 sec/mm2) was equivalent.     

Identification and characterization of a low-affinity granulocyte- macrophage colony-stimulating factor receptor on primary and cultured human melanoma cells

Hematopoietic growth factor receptors are present on cells of normal nonhematopoietic tissues such as endothelium and placenta. We previously demonstrated functional human granulocyte-macrophage colony- stimulating factor (GM-CSF) receptors on small cell carcinoma of the lung cell lines, and others have reported that certain solid tumor cell lines respond to GM-CSF in clonogenic assays. In the current study, we examine human melanoma cell lines and fresh specimens of melanoma to determine whether they have functional GM-CSF receptors. Scatchard analyses of 125I-GM-CSF equilibrium binding to melanoma cell lines showed a mean of 542 +/- 67 sites per cell with a kd of 0.72 +/- 0.14 nmol/L. Cross-linking studies in the melanoma cell line, M14, showed a major GM-CSF receptor species of 84,000 daltons. Under the conditions tested, the M14 cells did not have a proliferative response to GM-CSF in vitro, nor was any induction of primary response genes detected by Northern analysis in response to GM-CSF. Studies to determine internal translocation of the receptor-ligand complex indicated less than 10% of the 125I-GM-CSF internalized was specifically bound to receptors. Primary melanoma cells from five surgical specimens had GM-CSF receptors; Scatchard analysis was performed on one sample, showing 555 sites/cell with a kd of 0.23 nmol/L. These results indicate that human tumor cells may express a low-affinity GM-CSF receptor protein that localizes to the cell surface and binds ligand, but lacks functional components or accessory factors needed to transduce a signal.     

Extravasating Contrast Material on Angiography Following Carotid Angioplasty and Stenting: Not Necessarily Subarachnoid Hemorrhage

We describe a case of asymptomatic extravasation of iodinated contrast material into the sulci on digital subtraction angiography following carotid angioplasty and stenting resulting in sulcal hyperdensity on computed tomography (CT). We believe the mechanism for this observation is hyperperfusion injury and that in the absence of any associated clinical signs, it should not be considered alarming for subarachnoid hemorrhage.