1,329 research outputs found

    Interplay between the alpharetroviral Gag protein and SR proteins SF2 and SC35 in the nucleus

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    Retroviruses are positive-sense, single-stranded RNA viruses that reverse transcribe their RNA genomes into double-stranded DNA for integration into the host cell chromosome. The integrated provirus is used as a template for the transcription of viral RNA. The full-length viral RNA can be used for the translation of the Gag and Gag-Pol structural proteins or as the genomic RNA (gRNA) for encapsidation into new virions by the Gag protein. The mechanism by which Gag selectively incorporates unspliced gRNA into virus particles is poorly understood. Although Gag was previously thought to localize exclusively to the cytoplasm and plasma membrane where particles are released, we found that the Gag protein of Rous sarcoma virus, an alpharetrovirus, undergoes transient nuclear trafficking. When the nuclear export signal of RSV Gag is mutated (Gag.L219A), the protein accumulates in discrete subnuclear foci reminiscent of nuclear bodies such as splicing speckles, paraspeckles, and PML bodies. In this report, we observed that RSV Gag.L219A foci appeared to be tethered in the nucleus, partially co-localizing with the splicing speckle components SC35 and SF2. Overexpression of SC35 increased the number of Gag.L219A nucleoplasmic foci, suggesting that SC35 may facilitate the formation of Gag foci. We previously reported that RSV Gag nuclear trafficking is required for efficient gRNA packaging. Together with the data presented herein, our findings raise the intriguing hypothesis that RSV Gag may co-opt splicing factors to localize near transcription sites. Because splicing occurs co-transcriptionally, we speculate that this mechanism could allow Gag to associate with unspliced viral RNA shortly after its transcription initiation in the nucleus, before the viral RNA can be spliced or exported from the nucleus as an mRNA template

    Positive impact of low-dose, high-energy radiation on bone in partial- and/or full-weightbearing mice

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    Astronauts traveling beyond low Earth orbit will be exposed to galactic cosmic radiation (GCR); understanding how high energy ionizing radiation modifies the bone response to mechanical unloading is important to assuring crew health. To investigate this, we exposed 4-mo-old female Balb/cBYJ mice to an acute space-relevant dose of 0.5 Gy 56Fe or sham (n = ~8/group); 4 days later, half of the mice were also subjected to a ground-based analog for 1/6 g (partial weightbearing) (G/6) for 21 days. Microcomputed tomography (µ-CT) of the distal femur reveals that 56Fe exposure resulted in 65-78% greater volume and improved microarchitecture of cancellous bone after 21 d compared to sham controls. Radiation also leads to significant increases in three measures of energy absorption at the mid-shaft femur and an increase in stiffness of the L4 vertebra. No significant effects of radiation on bone formation indices are detected; however, G/6 leads to reduced % mineralizing surface on the inner mid-tibial bone surface. In separate groups allowed 21 days of weightbearing recovery from G/6 and/or 56Fe exposure, radiation-exposed mice still exhibit greater bone mass and improved microarchitecture vs. sham control. However, femoral bone energy absorption values are no longer higher in the 56Fe-exposed WB mice vs. sham controls. We provide evidence for persistent positive impacts of high-LET radiation exposure preceding a period of full or partial weightbearing on bone mass and microarchitecture in the distal femur and, for full weightbearing mice only and more transiently, cortical bone energy absorption values

    Adult Comorbidity Evaluation 27 score as a predictor of survival in endometrial cancer patients

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    BACKGROUND The incidence of endometrial cancer increases with age and is associated with medical comorbidities such as obesity and diabetes. While a few cohort studies of less than 500 patients showed an association between comorbidity and survival in endometrial cancer patients, the degree of association needs to be better described. The Adult Comorbidity Evaluation 27 (ACE-27) is a validated comorbidity instrument that provides a score (0–3) based on the number and severity of medical comorbidities. OBJECTIVE This study was performed to explore the association between medical comorbidities and survival of endometrial cancer patients. STUDY DESIGN Patients diagnosed with endometrial cancer from 2000–2012 were identified from the prospectively maintained Siteman Cancer Center tumor registry. Patients undergoing primary surgical treatment for endometrioid, serous and clear cell endometrial carcinoma were included. Patients primarily treated with radiation, chemotherapy or hormone therapy were excluded. Patients with uterine sarcomas or neuroendocrine tumors were excluded. Patients with missing ACE-27 scores were also excluded from analysis. Information including patient demographics, ACE-27 score, tumor characteristics, adjuvant treatment and survival data were extracted from the database. The association of ACE-27 and overall as well as recurrence-free survival was explored in a multivariable Cox regression analysis after controlling for variables found to be significantly associated with survival in univariable analysis. RESULTS A total of 2073 patients with a median age of 61 years (range 20–94) at diagnosis were identified. ACE-27 score was 0, 1, 2 and 3 in 22%, 38%, 28% and 12% of patients, respectively. Stage distribution was I (73%), II (5%), III (15%) and IV (7%) and grade distribution was 1 (52%), 2 (23%) and 3 (25%). Most patients had endometrioid histology (87%) followed by serous (11%) and clear cell (3%). The median OS for the entire cohort was 54 months [95% confidence interval (CI) 3, 154 months] and median PFS was 50 months [95% CI 2, 154 months]., On univariable analysis, age, race, marital status, stage, grade, histology and treatment type were significantly associated with overall survival and recurrence-free survival. After adjusting for these covariates, patients with ACE-27 score of 2 had a 52% higher risk of death [95% CI 1.16, 2.00] and patients with ACE-27 score of 3 had a 2.35-fold increased risk of death [95% CI 1.73, 3.21] compared to patients with an ACE-27 score of 0. Similarly, patients with ACE-27 score of 2 had a 38% higher risk of recurrence [95% CI 1.07, 1.78] and patients with ACE-27 score of 3 had a 2.05-fold increased risk of recurrence [95% CI 1.53, 2.75] compared to patients with an ACE-27 score of 0. We found no interaction between ACE-27 score and age, stage or treatment type. CONCLUSIONS Our findings demonstrate the importance of comorbidities in estimating the prognosis of endometrial cancer patients, even after adjusting for age and known tumor-specific prognostic factors like stage, grade, histology and adjuvant treatment

    New tunnel diode for zero-bias direct detection for millimeter-wave imagers

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    High-resolution passive millimeter wave imaging cameras require per pixel detector circuitry that is simple, has high sensitivity, low noise, and low power. Detector diodes that do not require bias or local oscillator input, and have high cutoff frequencies are strongly preferred. In addition, they must be manufacturable in large quantities with reasonable uniformity and reproducibility. Such diodes have not been obtainable for W-band and above. We are developing zero-bias square-law detector diodes based on InAs/Alsb/GaAlSb heterostructures which for the first time offer a cost-effective solution for large array formats. The diodes have a high frequency response and are relatively insensitive to growth and process variables. The large zero- bias non-linearity in current floor necessary for detection arises from interband tunneling between the InAs and the GaAlSb layers. Video resistance can be controlled by varying an Alsb tunnel barrier layer thickness. Our analysis shows that capacitance can be further decreased and sensitivity increased by shrinking the diode area, as the diode can have very high current density. DC and RF characterization of these devices and an estimate of their ultimate frequency performance in comparison with commercially available diodes are presented
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