Citations

Neurohospitalists are an emerging subspecialty group in neurology. 1 A recent survey of neurohospitalists found 75% of respondents had completed general neurology residency plus additional fellowship training (54% vascular neurology, 13% neurocritical care, and 33% other). 2 A limited number of neurohospitalist fellowship positions 3 , 4 are offered in the United States, however, a standardized curriculum or subspecialty certification examination does not currently exist. Given the recent dialogue surrounding the utility of neurohospitalist fellowship training, the purpose of this article is to provide 2 contrasting perspectives on the perceived need for neurohospitalist fellowship training.

We used a novel adaptation of methods for microtubule polymerization in vitro to assess the MTOC activity of centrosomes in frozen-sectioned tissues. Remarkably, centrosomes of tissue sections retain the ability to nucleate microtubules even after several years of storage as frozen tissue blocks. Adaptations of these methods allow accurate counts of microtubules from individual cells and the quantitative estimation the MTOC activity of the intact tissue. These methods can be utilized to characterize MTOC activity in normal and diseased tissues and in particular tissues at different stages of development.

Background: Neurohospitalists may improve the efficiency and quality of care delivered to hospitalized patients with neurological disease. However, there is limited systematic data to support this hypothesis. The primary purpose of this study was to compare length of stay (LOS) for patients with ischemic stroke cared for by either neurohospitalists or community-based neurologists at a single institution. Methods: A retrospective chart review was performed for all patients with ischemic stroke discharged from St. Luke’s Hospital in Jacksonville, Florida, between January 2006 and December 2007. The LOS for patients cared for by neurohospitalists was compared to the LOS for patients cared for by community neurologists. Compliance with Joint Commission inpatient stroke quality metrics was also compared. Results: A total of 533 patients were discharged with a principal diagnosis of ischemic stroke over the 24-month study period. Neurohospitalists cared for 313 patients with mean (± SD) LOS of 4.9 (5.2) days (95% CI: 4.3-5.5 days), and community-based neurologists cared for 220 patients with a mean LOS of 6.5 (8.2) days (95% CI: 5.4-7.6 days). The mean LOS was significantly less for the neurohospitalists compared to the community-based neurologists ( P = .005). Neurohospitalists achieved a higher compliance rate in 10 of 11 inpatient stroke quality metrics and achieved significantly higher compliance rate of smoking cessation education ( P = .019). Conclusions: Neurohospitalists achieved significantly shorter LOS for patients with ischemic stroke compared to community-based neurologists. These data suggest that neurohospitalists can also improve compliance with quality metrics necessary for Joint Commission Primary Stroke Center designation.

Abstract Hepatocellular carcinoma (HCC), the primary malignancy of the liver, is the fourth leading cause of cancer deaths worldwide, with a 5-year survival rate of∼10%. Recently, a new multikinase inhibitor, sorafenib (Nexavar®), which mainly targets the VEGFR and the Raf/Mek/Erk pathways, has shown limited response rate and modest survival benefits in patients with advanced stage HCC. We hypothesize that there exist genetic alterations or contexts of vulnerability (COV) in cancer cells that dictate sensitivity to sorafenib. In order to identify specific COVs and obtain an increased understanding of drug's mechanism of action, we performed a custom chemosensitization high-throughput siRNA screen. We developed and optimized a sorafenib chemosensitization assay in 3 HCC cell lines, one of which, Hep3B, a AFP and HBsAg positive cell line, was selected for primary RNAi screening with a kinase siRNA library, which covers 700 genes (4 siRNA sequences per gene). Primary screen data was rigorously evaluated for multiple quality control metrics (transfection efficiency, CV values, accessing plate-to-plate and set-to-set variation) and found to exceed all expected performance parameters. The top sorefenib sensitizing hits were identified and supplemented with additional genes selected based on related biological concepts. This sensitization effect of the genes was further tested and compared in two additional HCC cell lines (HepG2 and PLC). Additionally, based on the sensitizer list from the RNAi screening, 11 chemical compounds were tested for synergistic combination with sorafenib. Notable synergism with sorafenib was observed in the combination with erlotinib or doxorubicin. More strikingly, we also observed synergy between sorafenib and multiple MEK inhibitors as well as gemcitabine in the selected HCC cell lines. Our data suggest that MEK inhibitors might improve the efficacy of sorafenib in HCC treatment in the clinic. Further mechanistic studies are being conducted for this particular combination. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-285.

Abstract Esophageal adenocarcinoma (EAC) is thought to arise from the metaplastic condition known as Barrett's esophagus (BE), which is caused by chronic inflammation due to gastroesophageal reflux disease. Since the molecular mechanisms underlying the pathogenesis of EAC are unknown, understanding EAC development mechanisms and their regulation is crucial for the treatment of EAC. Comparative genomic studies of evolutionarily similar and dissimilar species have been suggested as a means of studying the evolutionary biology in the species. Thus, we performed a cross-species comparison of gene expression patterns in human and rat tissues, uncovering the evolutionarily conserved gene expression patterns during EAC progression across both species. Using a non-carcinogenic rat model that progresses from normal esophagus to BE to EAC, we were able to identify the biological mechanisms of EAC development. We analyzed gene expression data from rat specimens (15 NE, 18 BE, and 30 EAC) as well as from human tissues (28NE, 72BE, and 75EAC). Using the presence of orthologous genes in both microarray platforms and various statistical tests, we uncovered a number of genes whose expression patterns were well conserved during progression from NE to BE in humans and rats. The expression of 869 genes was commonly altered when NE progressed to BE in both humans and rats (P<0.005). One of the most significantly conserved signaling pathways during the progression from NE to BE was IL-6-mediated E2F transcription factor1 (E2F1). The increased E2F1 induced activation of CCNA2, CCNB2, CCND1, CCNE 1 and 2, CDC 2 and 6, CASP3, CASP6, CASP8, CASP9, and Rad 51, which are important genes for the regulation of cell cycle, apoptosis, and DNA repair. These up-regulated genes may consequently cause abnormal cell cycle regulation and induce dysplasia and metaplasia of normal esophagus tissue during NE to BE progression. During BE to EAC progression in both species, 541 gene expressions were altered (P<0.005). An increased TGF-β/RAS/SPI1 signaling pathway significantly increased the expression of SPARC and SPP1 during progression from BE to EAC. Increased SPP1 and SPARC activated MMP9, CCL2, CCL4, COL1A1, COL3A1, and SNAL1, which mostly function in invasion, cell adhesion, and migration. Intriguingly, SPP1 and SPARC already had been discovered in our previous study (Kim et al.,) as markers of poor prognosis for EAC patients, strongly indicating that SPP1 and SPARC are also genetic determinants for progression to EAC. In conclusion, systems-level characterization of gene expression data from humans and a rodent model shows evolutionarily conserved genes and pathways during EAC progression, and these genes and pathways could become reliable biomarkers for early detection, or therapeutic targets for the treatment of EAC patients. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2005.

Abstract Microarray technologies are powerful assays, which can identify copy-number abnormalities (CNA) underlying the pathogenesis of cancer. Several commercial arrays are available but it is unclear which is the best platform. We did a side-by-side comparison between two leading arrays; the Affymetrix SNP6 and Agilent 1M, to compare data compression, noise, gene and exon coverage, and CNA detection. Five samples were run on both platforms and analyzed as recommended by the manufacturer. We first performed an in silico comparison to define the number of probes per serial 5k interval, number of probes per gene and exon, and the coefficient of variation of different smoothing windows. Comparing the CV of the two arrays showed a similar level of variation between a 3 and 5 probe averaging on the 1M and SNP6, respectively. Using these smoothing levels the 1M interrogates 81.2% of the genes in the genome compared to 69.3% on the SNP6. At the exon level the 1M has at least one probe in 64.8% compared to 41.2% on the SNP6. We observed a similar level of data compression (∼10%) on the two arrays but the SNP6 had nearly twice the noise (SD 0.38 versus 0.21). Finally, there was a marked increment in the number of CNA identified by 1M (mean of 78.5) than SNP6.0 (59.5). In this comparison the Agilent 1M out performed the Affymetrix SNP6. Even with half the number of probes, the 1M was superior in CNA detection, gene/exon coverage and showed less signal variation. A comparison with previous platforms showed that these two arrays did not identify new gene amplifications but did detect new deletions, however, neither platform detected several known deletions detected by other methods. Therefore, we designed a custom, exon-centered, 2×400K array (Agilent) with the goal of identifying additional deletions. The design outline was: a) all the probes from the Agilent CGH 44K array; b) 3 probes per exon across the human exome; c) high resolution tiling of 1450 cancer implicated genes; and d) tiling the 4kb flanking all MIRs. To improve performance, we only included probes with performance scores higher than 0.8 and 0.85 in queries b) and c), respectively. Lastly, 15000 probes from the 1M array that map to exons missed by our design parameters were also included. Our custom array has half the probes (415K) of the 1M (960K) and 4.5x less than the SNP6 (1.85M) but shows the best gene and exon coverage. When the minimum number of probes needed for calculating a CNA is considered, 86% of genes are interrogated compared to 81.2% (1M) and 69.3% (SNP6). The difference is even more marked at the exon level with 84% covered by at least one probe and at least 63.2% interrogated by two probes compared to 5.3% (1M) and 18.0% (SNP6). The promising in silico comparison of this exon-centered array, its more stringent design parameters in combination with significantly reducing the cost per run should make this a very promising array design for CNA analysis of tumor samples in the future Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4957.

Abstract Background. Third generation aromatase inhibitors (AIs) have been shown to be superior to tamoxifen in multiple randomized clinical trials and become the new standard of treatment for postmenopausal women with early or advanced endocrine-sensitive breast cancer. It is thus important to identify biomarkers predicting resistance to AIs so that alternative therapeutic options can be employed. A two gene expression index, HOXB13:IL17BR, and HOXB13 in particular, has been shown to be a negative predictor of clinical benefit from tamoxifen. It is unclear whether HOXB13:IL17BR or HOXB13 is also predictive of AI therapy.Methods. We performed a retrospective analysis of a phase II randomized neoadjuvant study of everolimus+letrozole vs. placebo+letrozole in patients with estrogen receptor-positive breast cancer. Total RNA was extracted from frozen tissue biopsies taken either prior to treatment or after 15 days of treatment. HOXB13:IL13BR and a molecular grade index (MGI) were measured in 107 pre-treatment samples and 111 samples after 15 days of treatment. Antiproliferative response as defined by a ln[Ki767] <1 at day 15 in the samples analyzed was correlated with these gene expression indices.Results. In the placebo+letrozole treatment arm, the antiproliferative response rate was 30% (14/47). Using a pre-specified cutpoint of 0.06, the response rate was 40% for low HOXB13:IL17BR patients, compared to 12% for high HOXB13:IL17BR patients (p=0.05). In the everolimus+letrozole arm, the antiproliferative response rate in the samples analyzed was 55% (33/60), and the response rates for low and high HOXB13:Il17BR patients were 70% and 37% (p=0.02), respectively. When examined separately, high HOXB13 expression was significantly associated with nonresponse to therapy (everolimus+letrozole arm, p=0.02; placebo+letrozle arm, p=0.03), but IL17BR was not (everolimus+letrozole arm, p=0.6; placebo+letrozle arm, p=0.88). As expected, we observed a significant correlation between MGI and Ki67 staining (Spearman r=0.67, p<0.0001).Conclusions. High HOXB13:IL17BR index and high HOXB13 expression may identify a possible subset of patients with estrogen receptor-positive tumor that could be less responsive to aromatase inhibitors such as letrozole. Furthermore, use of MGI may enable rapid assessment of antiproliferative response by fine needle aspiration. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 2120.

Abstract To better understand the molecular mechanisms behind esophageal adenocarcinoma (EAC) tumorigenesis, we used high-density single nucleotide polymorphism arrays to profile chromosomal aberrations at each of the four sequential progression stages, Barrett's metaplasia (BM), low-grade dysplasia (LGD), high-grade dysplasia (HGD), and EAC, in 101 patients. We observed a significant trend toward increasing loss of chromosomes with higher progression stage. For BM, LGD, HGD, and EAC, respectively, the average numbers of chromosome arms with loss per sample were 0.30, 3.21, 7.70, and 11.90 (P for trend = 4.82 × 10−7), and the mean percentages of single nucleotide polymorphisms with allele loss were 0.1%, 1.8%, 6.6%, and 17.2% (P for trend = 2.64 × 10−6). In LGD, loss of 3p14.2 (68.4%) and 16q23.1 (47.4%) was limited to narrow regions within the FHIT (3p14.2) and WWOX (16q23.1) genes, whereas loss of 9p21 (68.4%) occurred in larger regions. A significant increase in the loss of other chromosomal regions was seen in HGD and EAC. Loss of 17p (47.6%) was one of the most frequent events in EAC. Many recurrent small regions of chromosomal loss disrupted single genes, including FHIT, WWOX, RUNX1, KIF26B, MGC48628, PDE4D, C20orf133, GMDS, DMD, and PARK2, most of which are common fragile site regions in the human genome. However, RUNX1 at 21q22 seemed to be a potential tumor suppressor gene in EAC. Amplifications were less frequent than losses and mostly occurred in EAC. 8q24 (containing Myc) and 8p23.1 (containing CTSB) were the two most frequently amplified regions. In addition, a significant trend toward increasing amplification was associated with higher progression stage. Cancer Prev Res; 3(9); 1176–86. ©2010 AACR.

Background and Purpose— Warfarin reduces stroke risk by approximately 60% in patients with atrial fibrillation (AF). Differences in awareness and treatment of AF may contribute to racial and geographic disparities in stroke mortality. The objective was to examine predictors of awareness of the diagnosis of AF and treatment with warfarin. Methods— RE asons for G eographic a nd R acial D ifferences in S troke (REGARDS) is a national, population-based, longitudinal study of 30 239 blacks and whites ≥45 years old with oversampling from blacks and the southeastern stroke belt states. Participants were enrolled January 2003 to October 2007. Data were collected using telephone interview, in-home evaluation, and self-administered questionnaires. The main variable of awareness of AF was defined by a positive answer to “Has a doctor or other health professional ever told you that you had atrial fibrillation?” and whether there was evidence of treatment on the basis of an in-home medications inventory. Results— From baseline electrocardiograms, 432 individuals (88 black and 344 white) had AF. Of these, 88% (360 of 409) had at least 1 additional CHADS 2 stroke risk factor and 60% (258 of 432) were aware of their AF. The odds of blacks being aware of their AF were one third that of whites (OR=0.32; 95% CI: 0.20 to 0.52). Among those aware, the odds of blacks being treated with warfarin were only one fourth as great as whites (OR=0.28; 0.13 to 0.60). Conclusion— Blacks were less likely than whites to be aware of having AF or to be treated with warfarin. Potential reasons for the racial disparity in warfarin treatment warrant further investigation.