102 research outputs found
NASA Plum Brook Station In-Space Propulsion Facility Test Stand Characterization Hot Fire Test
A test facility modification to enable small scale altitude propulsion testing at the NASA Glenn Research Center's In-Space Propulsion (ISP) Facility was verified with a hot fire test campaign. As the facility's primary steam supply system undergoes refurbishment, the alternate facility configuration, known as the "vacuum accumulator" mode, would enable rocket engine testing up to 10,000 lbf thrust. The NASA Johnson Space Center developed the vehicle for the verification test campaign: the Integrated Cryogenic Propulsion Test Article (ICPTA). Constructed primarily from assets of the former Morpheus Project, the ICPTA provided an integrated liquid oxygen (LOX) / liquid methane (LCH4) propulsion system including a 2,800 lbf thrust main engine. The ISP Facility's vacuum accumulator configuration leveraged the large test volume of the facility and a diffuser insert to maintain altitude conditions. During hot fire, the ICPTA main engine "started" the diffuser insert constructed for the test campaign. As a result, the test chamber upstream of the diffuser insert remained at altitude conditions throughout the hot fire. Upon engine shut down, a backflow deflector mitigated blow back into the test chamber by restricting the mass flow and redirecting it away from the test article. The test campaign successfully characterized the performance of the vacuum accumulator configuration. In addition, it provided an opportunity to collect data for an integrated LOX / LCH4 propulsion system in an altitude and thermal vacuum environment
161. The Potential Role of Extensor Muscle Fatigue in the Onset of Intervertebral Disc Degeneration: A Novel In Vivo Model
BACKGROUND CONTEXT: Occupation is strongly correlated to low back pain (LBP). Specific occupational activities associated with low back pain include poor posture, whole body vibration, and repetitive lifting. These activities have a common link: they result in fatigue of the primary spinal extensor musculature. This fatigue may lead to increased intervertebral loading - a stimulus for disc degeneration. If true, this association could provide a vital connection between detrimental physical activities and LBP. However, the link between muscle fatigue and increased load across the disc space has never been quantified in vivo.
PURPOSE: The purpose of this study was to develop and test a wireless multi-axial force-sensing implant and large animal model of primary extensor muscle fatigue. Combined, these tools allow measurement of in vivo spinal forces during muscle fatigue to quantify changes in spine loading
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Loss of SMAD3 Promotes Vascular Remodeling in Pulmonary Arterial Hypertension via MRTF Disinhibition.
RATIONALE: Vascular remodeling in pulmonary arterial hypertension (PAH) results from smooth muscle cell hypertrophy and proliferation of vascular cells. Loss of BMPR-II (bone morphogenetic protein receptor 2) signaling and increased signaling via TGF-β (transforming growth factor β) and its downstream mediators SMAD (small body size [a C. elegans protein] mothers against decapentaplegic [a Drosophila protein family])-2/3 has been proposed to drive lung vascular remodeling; yet, proteomic analyses indicate a loss of SMAD3 in PAH. OBJECTIVES: We proposed that SMAD3 may be dysregulated in PAH and that loss of SMAD3 may present a pathophysiological master switch by disinhibiting its interaction partner, MRTF (myocardin-related transcription factor), which drives muscle protein expression. METHODS: SMAD3 levels were measured in lungs from PAH patients, rats treated either with Sugen/hypoxia or monocrotaline (MCT), and in mice carrying a BMPR2 mutation. In vitro, effects of SMAD3 or BMPR2 silencing or SMAD3 overexpression on cell proliferation or smooth muscle hypertrophy were assessed. In vivo, the therapeutic and prophylactic potential of CCG1423, an inhibitor of MRTF, was investigated in Sugen/hypoxia rats. MEASUREMENTS AND MAIN RESULTS: SMAD3 was downregulated in lungs of patients with PAH and in pulmonary arteries of three independent PAH animal models. TGF-β treatment replicated the loss of SMAD3 in human pulmonary artery smooth muscle cells (huPASMCs) and human pulmonary artery endothelial cells. SMAD3 silencing increased proliferation and migration in huPASMCs and human pulmonary artery endothelial cells. Coimmunoprecipitation revealed reduced interaction of MRTF with SMAD3 in TGF-β-treated huPASMCs and pulmonary arteries of PAH animal models. In huPASMCs, loss of SMAD3 or BMPR-II increased smooth muscle actin expression, which was attenuated by MRTF inhibition. Conversely, SMAD3 overexpression prevented TGF-β-induced activation of an MRTF reporter and reduced actin stress fibers in BMPR2-silenced huPASMCs. MRTF inhibition attenuated PAH and lung vascular remodeling in Sugen/hypoxia rats. CONCLUSIONS: Loss of SMAD3 presents a novel pathomechanism in PAH that promotes vascular cell proliferation and-via MRTF disinhibition-hypertrophy of huPASMCs, thereby reconciling the parallel induction of a synthetic and contractile huPASMC phenotype
A multicenter experience with the Talent endovascular graft for the treatment of abdominal aortic aneurysms
AbstractObjective: The Talent endovascular graft has been used in the treatment of abdominal aortic aneurysms (AAAs) in more than 13,000 patients worldwide. However, information regarding the results of its use has been limited. This report describes the experience with 368 patients with AAAs who underwent treatment at four medical centers as part of an investigator-sponsored investigational device exemption trial. Methods: Patients with AAAs were enrolled at four sites during a 32-month period from January 1999 to July 2001. All patients underwent treatment for infrarenal AAA with the Talent endovascular graft. Repair was performed with transrenal stent fixation under epidural (362/368 patients; 98.3%), local (4/368 patients; 1.1%), or general (2/368 patients; 0.5%) anesthesia. The average diameters were: maximum aortic aneurysm, 6.2 Âą 1.2 cm; proximal aortic fixation site, 2.6 Âą 0.4 cm; and distal iliac fixation site, 1.4 Âą 0.6 cm. Bifurcated grafts were used in 276 of 366 patients (75%), aortouniiliac in 57 of 366 patients (16%), and tube aortoaortic in 33 of 366 patients (9%). Multiple comorbid medical conditions were present in all patients (average, 4.7 conditions/patient). The mean age was 75.8 years, and 85% of the patients were male. Follow-up period ranged from 2 to 33 months (mean, 7.3 months). Results: Endovascular graft deployment was accomplished in 366 of 368 patients. In the 263 patients followed for at least 6 months after endovascular repair, AAA diameter decreased by 5 mm or more in 83 patients (32%); diameter remained unchanged (change < 5 mm) in 157 patients (60%) and increased by 5 mm or more in 23 patients (8.7%). Major morbidity occurred in 46 of 368 patients (12.5%), and minor morbidity occurred in 31 of 368 (8.4%). The 30-day mortality rate was 1.9%. Secondary procedures were performed in 32 patients (8.7%). Late rupture occurred in two patients, and late deaths unrelated to AAA occurred in 32 patients (8.7%) during the follow-up period. The primary technical success rate for all patients was 93.4%. The 30-day primary procedural success rate was 73.3%. The 30-day secondary procedural success rate was significantly higher at 85.8%. Computed tomographic scan was performed within 1 month after surgery in 349 patients. An endoleak was present in 43 of 349 patients (12.3%). These endoleaks were comprised of 10 attachment site (type I; 2.9%), 31 retrograde side-branch (type II; 8.9%), and two transgraft (type III; 0.6%). Conclusion: These midterm findings show a high degree of technical and procedural success achieved in a patient population with extensive comorbid medical illnesses with low perioperative morbidity and mortality rates. Further follow-up study will be necessary to determine the effectiveness of the Talent endograft for the long-term treatment of AAA. (J Vasc Surg 2002;35:1123-8.
Circulating ketone bodies and mortality in heart failure: a community cohort study
BackgroundThe relationship between ketone bodies (KB) and mortality in patients with heart failure (HF) syndrome has not been well established.ObjectivesThe aim of this study is to assess the distribution of KB in HF, identify clinical correlates, and examine the associations between plasma KB and all-cause mortality in a population-based HF cohort.MethodsThe plasma KB levels were measured by nuclear magnetic resonance spectroscopy. Multivariable linear regression was used to examine associations between clinical correlates and KB levels. Proportional hazard regression was employed to examine associations between KB (represented as both continuous and categorical variables) and mortality, with adjustment for several clinical covariates.ResultsAmong the 1,382 HF patients with KB measurements, the median (IQR) age was 78 (68, 84) and 52% were men. The median (IQR) KB was found to be 180 (134, 308) ÎźM. Higher KB levels were associated with advanced HF (NYHA class IIIâIV) and higher NT-proBNP levels (both Pâ<â0.001). The median follow-up was 13.9 years, and the 5-year mortality rate was 51.8% [95% confidence interval (CI): 49.1%â54.4%]. The risk of death increased when KB levels were higher (HRhigh vs. low group 1.23; 95% CI: 1.05â1.44), independently of a validated clinical risk score. The association between higher KB and mortality differed by ejection fraction (EF) and was noticeably stronger among patients with preserved EF.ConclusionsMost patients with HF exhibited KB levels that were consistent with those found in healthy adults. Elevated levels of KB were observed in patients with advanced HF. Higher KB levels were found to be associated with an increased risk of death, particularly in patients with preserved EF
Human T cell recognition of the blood stage antigen Plasmodium hypoxanthine guanine xanthine phosphoribosyl transferase (HGXPRT) in acute malaria
<p>Abstract</p> <p>Background</p> <p>The <it>Plasmodium </it>purine salvage enzyme, hypoxanthine guanine xanthine phosphoribosyl transferase (HGXPRT) can protect mice against <it>Plasmodium yoelii </it>pRBC challenge in a T cell-dependent manner and has, therefore, been proposed as a novel vaccine candidate. It is not known whether natural exposure to <it>Plasmodium falciparum </it>stimulates HGXPRT T cell reactivity in humans.</p> <p>Methods</p> <p>PBMC and plasma collected from malaria-exposed Indonesians during infection and 7â28 days after anti-malarial therapy, were assessed for HGXPRT recognition using CFSE proliferation, IFNÎł ELISPOT assay and ELISA.</p> <p>Results</p> <p>HGXPRT-specific T cell proliferation was found in 44% of patients during acute infection; in 80% of responders both CD4<sup>+ </sup>and CD8<sup>+ </sup>T cell subsets proliferated. Antigen-specific T cell proliferation was largely lost within 28 days of parasite clearance. HGXPRT-specific IFN-Îł production was more frequent 28 days after treatment than during acute infection. HGXPRT-specific plasma IgG was undetectable even in individuals exposed to malaria for at least two years.</p> <p>Conclusion</p> <p>The prevalence of acute proliferative and convalescent IFNÎł responses to HGXPRT demonstrates cellular immunogenicity in humans. Further studies to determine minimal HGXPRT epitopes, the specificity of responses for Plasmodia and associations with protection are required. Frequent and robust T cell proliferation, high sequence conservation among <it>Plasmodium </it>species and absent IgG responses distinguish HGXPRT from other malaria antigens.</p
IL-1-induced Bhlhe40 identifies pathogenic T helper cells in a model of autoimmune neuroinflammation
The features that define autoreactive T helper (Th) cell pathogenicity remain obscure. We have previously shown that Th cells require the transcription factor Bhlhe40 to mediate experimental autoimmune encephalomyelitis (EAE), a mouse model of multiple sclerosis. Here, using Bhlhe40 reporter mice and analyzing both polyclonal and TCR transgenic Th cells, we found that Bhlhe40 expression was heterogeneous after EAE induction, with Bhlhe40-expressing cells displaying marked production of IFN-Îł, IL-17A, and granulocyte-macrophage colony-stimulating factor. In adoptive transfer EAE models, Bhlhe40-deficient Th1 and Th17 cells were both nonencephalitogenic. Pertussis toxin (PTX), a classical co-adjuvant for actively induced EAE, promoted IL-1β production by myeloid cells in the draining lymph node and served as a strong stimulus for Bhlhe40 expression in Th cells. Furthermore, PTX co-adjuvanticity was Bhlhe40 dependent. IL-1β induced Bhlhe40 expression in polarized Th17 cells, and Bhlhe40-expressing cells exhibited an encephalitogenic transcriptional signature. In vivo, IL-1R signaling was required for full Bhlhe40 expression by Th cells after immunization. Overall, we demonstrate that Bhlhe40 expression identifies encephalitogenic Th cells and defines a PTXâIL-1âBhlhe40 pathway active in EAE
Determinants and impact of role-related time use allocation on self-reported health among married men and women: a cross-national comparative study
Background Research on the effects of marriage on health maintains that there is a gender-specific gradient, with men deriving far greater benefits than women. One reason provided for this difference is the disproportionate amount of time spent by women on housework and childcare. However, this hypothesis has yet to be explicitly tested for these role-related time use activities. This study provides empirical evidence on the association between role-related time use activities (i.e. housework, childcare and paid work) and self-reported health among married men and women.
Methods Data from the Multinational Time Use Study (MTUS) on 32,881 men and 26,915 women from Germany, Italy, Spain, the UK and the US were analyzed. Seemingly unrelated regression (SUR) models and multivariable logistic regression were used to estimate the association between role-related time use activities and self-reported health among married men and women.
Results The findings showed that education, occupation and number of children under 18 years old in the household were the most consistent predictors of time allocation among married men and women. Significant gender differences were also found in time allocation, with women sacrificing paid working time or reducing time devoted to housework for childcare. Men, in contrast, were less likely to reduce paid working hours to increase time spent on childcare, but instead reduced time allocation to housework. Allocating more time to paid work and childcare was associated with good health, whereas time spent on housework was associated with poor health, especially among women.
Conclusions Time allocation to role-related activities have differential associations on health, and the effects vary by gender and across countries. To reduce the gender health gap among married men and women, public policies need to take social and gender roles into account
RNA Polymerase II Pausing Downstream of Core Histone Genes Is Different from Genes Producing Polyadenylated Transcripts
Recent genome-wide chromatin immunoprecipitation coupled high throughput sequencing (ChIP-seq) analyses performed in various eukaryotic organisms, analysed RNA Polymerase II (Pol II) pausing around the transcription start sites of genes. In this study we have further investigated genome-wide binding of Pol II downstream of the 3Ⲡend of the annotated genes (EAGs) by ChIP-seq in human cells. At almost all expressed genes we observed Pol II occupancy downstream of the EAGs suggesting that Pol II pausing 3Ⲡfrom the transcription units is a rather common phenomenon. Downstream of EAGs Pol II transcripts can also be detected by global run-on and sequencing, suggesting the presence of functionally active Pol II. Based on Pol II occupancy downstream of EAGs we could distinguish distinct clusters of Pol II pause patterns. On core histone genes, coding for non-polyadenylated transcripts, Pol II occupancy is quickly dropping after the EAG. In contrast, on genes, whose transcripts undergo polyA tail addition [poly(A)+], Pol II occupancy downstream of the EAGs can be detected up to 4â6 kb. Inhibition of polyadenylation significantly increased Pol II occupancy downstream of EAGs at poly(A)+ genes, but not at the EAGs of core histone genes. The differential genome-wide Pol II occupancy profiles 3Ⲡof the EAGs have also been confirmed in mouse embryonic stem (mES) cells, indicating that Pol II pauses genome-wide downstream of the EAGs in mammalian cells. Moreover, in mES cells the sharp drop of Pol II signal at the EAG of core histone genes seems to be independent of the phosphorylation status of the C-terminal domain of the large subunit of Pol II. Thus, our study uncovers a potential link between different mRNA 3Ⲡend processing mechanisms and consequent Pol II transcription termination processes
Track D Social Science, Human Rights and Political Science
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138414/1/jia218442.pd
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