The influenza A virus genome is composed of eight negativesense RNA segments (22, 26), which can encode up to 11 viral proteins (3, 23). Upon infection, the viral RNA (vRNA) is transported to the nucleus, the site of vRNA transcription and replication. At late stages of the infectious cycle, the viral ribonucleoprotein complex, composed of the three influenza polymerase proteins, the nucleoprotein, and vRNA, is exported from the nucleus in association with the influenza virus matrix (M1) and nuclear export (NEP) proteins (5). The final step of the virus replication cycle involves the assembly of the viral structural proteins and the packaging of the viral genome. For a virus particle to be fully infectious, it must contain a full complement of the eight vRNA segments. The process by which this packaging occurs is not well understood. However, it is known that vRNA is specifically packaged in preference to cellular RNAs and that the different vRNAs are present in an equimolar ratio within a population of virus particles (21).Two models have been proposed for the packaging of vRNA into budding virions: the random incorporation model and the selective incorporation model (23). The random incorporation model assumes that a common structural feature is present on all vRNAs which enables them to be randomly incorporated into budding virions. In other words, the virus randomly incorporates vRNA into budding virions and does not differentiate among the different segments (4). This means that the likelihood of a virion obtaining a full complement of the eight vRNAs is determined entirely by chance. This model is supported by evidence that infectious viruses may possess more than eight vRNAs (8). Mathematical modeling suggests that if eight vRNAs are packaged randomly, 0.24% of released virus particles would contain a full complement of vRNAs and be infectious (1,8). If 12 vRNAs were packaged randomly, the mathematical models suggest that infectivity increases to approximately 10%, which is comparable with the experimental data (6). As only 1 to 2% of the weight of the influenza virus particle is vRNA, it is difficult to accurately quantify the exact number of vRNA segments packaged. The earliest evidence suggesting that influenza vRNAs have packaging signals was from Luytjes et al. (14). Utilizing both the 3Ј and 5Ј terminal untranslated regions of the NS gene, it was possible to package a chloramphenicol acetyltransferase gene into influenza virus particles. This foreign gene was packaged into infectious particles and passaged several times, suggesting that the terminal 22 5Ј and 26 3Ј nucleotides are sufficient to provide the signals for RNA transcription and replication as well as for the packaging of RNA into influenza virus particles.The selective incorporation model suggests that each vRNA segment contains a unique "packaging signal" allowing it to act independently, with each vRNA segment being packaged selectively. Evidence supporting this model comes from several reports demonstrating that defective interfering ...

Metastasis is the major cause of cancer mortality. A more thorough understanding of the mechanisms driving this complex multistep process will aid in the identification and characterization of therapeutically targetable genetic drivers of disease progression. We demonstrate that KLF6-SV1, an oncogenic splice variant of the KLF6 tumor suppressor gene, is associated with increased metastatic potential and poor survival in a cohort of 671 lymph node–negative breast cancer patients. KLF6-SV1 overexpression in mammary epithelial cell lines resulted in an epithelial-to-mesenchymal–like transition and drove aggressive multiorgan metastatic disease in multiple in vivo models. Additionally, KLF6-SV1 loss-of-function studies demonstrated reversion to an epithelial and less invasive phenotype. Combined, these findings implicate KLF6-SV1 as a key driver of breast cancer metastasis that distinguishes between indolent and lethal early-stage disease and provides a potential therapeutic target for invasive breast cancer.

OBJECTIVE-Although the incidence of stroke after carotid endarterectomy (CEA) is low (1-3%), approximately 25% of patients experience subtle declines in postoperative neuropsychometric function. No studies have investigated the risk factors for this neurocognitive change. We sought to identify predictors of postoperative neurocognitive dysfunction.METHODS-We enrolled 186 CEA patients, with both symptomatic and asymptomatic stenosis, to undergo a battery of neuropsychometric tests preoperatively and on postoperative Days 1 and 30. Neurocognitive dysfunction was defined as a two standard deviation decline in performance compared with a similarly aged control group of lumbar laminectomy patients. Univariate logistic regression was performed for age, sex, obesity, smoking, symptomatology, diabetes mellitus, hypertension, hypercholesterolemia, use of statin medication, previous myocardial infarction, previous CEA, operative side, duration of surgery, duration of carotid cross-clamp, and weightadjusted doses of midazolam and fentanyl. Variables achieving univariate P < 0.10 were included in a multivariate analysis. Data is presented as (odds ratio, 95% confidence interval, P-value). CONCLUSIONS-Advanced age and diabetes predispose to neurocognitive dysfunction after CEA. These results are consistent with risk factors for neurocognitive dysfunction after coronary bypass and major stroke after CEA, supporting an underlying ischemic pathophysiology. Further work is necessary to determine the role these neurocognitive deficits may play in appropriately selecting patients for CEA. KeywordsCarotid endarterectomy; Cerebral ischemia; Neuropsychological tests; Risk factorsCarotid endarterectomy (CEA) reduces the risk of future stroke in patients with high-grade stenosis (5,10,15,25). However, approximately 25% of CEA patients experience declines in postoperative neurocognitive function that are detected by a battery of neuropsychometric tests (NPMTs) (12,13). Although the mechanism of post-CEA neurocognitive decline is poorly understood, it is thought to be ischemic in nature, and may be owing to hypoperfusion during carotid artery cross-clamping or the dislodgement of microemboli during vessel dissection and plaque removal.To date, no studies have thoroughly investigated the risk factors for these neurocognitive changes after CEA. With nearly 100,000 CEAs performed annually (5,25), many for borderline indications with small absolute benefit (11,35), understanding the variables that predispose to subtle changes in cerebral function is crucial in appropriate patient selection. We sought to identify factors that predict postoperative neurocognitive dysfunction. PATIENTS AND METHODS Study PopulationOne hundred and eighty six consecutive patients undergoing elective CEA for both symptomatic and asymptomatic carotid artery stenosis were prospectively enrolled in this institutional review board-approved study. All CEA patients had 60% or greater stenosis of the operative carotid artery. After obtaining written informed conse...

Gastric cancer is the second most common cancer and a leading cause of cancer-related death worldwide. The KLF6 tumour suppressor gene has been previously shown to be inactivated in a number of human cancers through loss of heterozygosity (LOH), somatic mutation, decreased expression, and increased alternative splicing into a dominant negative oncogenic splice variant, KLF6-SV1. In this present study, thirty seven gastric cancer samples were analysed for the presence of loss of heterozygosity (LOH) of the KLF6 locus and somatic mutation. In total, 18 of 34 (53%) of the gastric cancer samples analysed demonstrated KLF6 locus specific loss. Four missense mutations, T179I, R198G, R71Q, and S180L were detected. Interestingly, two of these mutations R71Q and S180L have been identified independently by several groups in various malignancies including prostate, colorectal and gastric cancer. In addition, decreased wtKLF6 expression was associated with loss of the KLF6 locus and was present in 48% of primary gastric tumour samples analysed. Functional studies confirmed that wtKLF6 suppressed proliferation of gastric cancer cells via transcriptional regulation of the cyclin dependent kinase inhibitor p21 and the oncogene c-myc. Functional characterization of the common tumour-derived mutants demonstrated that the mutant proteins fail to suppress proliferation and function as dominant negative regulators of wtKLF6 function. Furthermore, stable overexpression of the R71Q and S180L tumour derived mutants in the gastric cancer cell line, Hs746T resulted in increased tumourigenicity in vivo. Combined, these findings suggest an important role for the KLF6 tumour suppressor gene in gastric cancer development and progression and identify several highly cancer-relevant signaling pathways regulated by the KLF6 tumour suppressor gene.