2,287 research outputs found
Thermostructural applications of heat pipes
The feasibility of integrating heat pipes in high temperature structure to reduce local hot spot temperature was evaluated for a variety of hypersonic aerospace vehicles. From an initial list of twenty-two potential applications, the single stage to orbit wing leading edge showed the greatest promise and was selected for preliminary design of an integrated heat pipe thermostructural system. The design consisted of a Hastelloy X assembly with sodium heat pipe passages aligned normal to the wing leading edge. A d-shaped heat pipe cross section was determined to be optimum from the standpoint of structural weight
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HAGE, a cancer/testis antigen expressed at the protein level in a variety of cancers
The search for novel tumour antigens that are either uniquely expressed or over-expressed in a wide variety of tumours is still ongoing. Because of their expression in a broad spectrum of cancers and limited expression in normal tissues, cancer/testis antigens are considered to be potentially reliable targets for immunotherapy of cancer in general. The helicase antigen HAGE has been identified as a cancer/testis antigen. However, little is known about its expression in normal and cancer tissues. Using a newly developed antibody against HAGE, specific staining of its expression by immunohistochemistry was validated and optimised on murine tumours transfected to express the HAGE protein. The antibody was subsequently used to determine HAGE expression in normal human and cancer tissue microarrays. HAGE protein expression was confirmed in 75% (12/16) of carcinomas as compared to normal tissues, which either did not express HAGE at all or expressed HAGE at very low levels with the exception of testis. Interestingly, discrepancies were also found between mRNA analysis by real time quantitative PCR (RT-qPCR) and protein analysis by immunohistochemistry, emphasising the need to validate the expression of cancer/testis antigens at the protein level prior to the development of new vaccine strategies. HAGE is therefore proposed to be a valid candidate for designing a broad spectrum vaccine against cancer
Engineering tyrosine-based electron flow pathways in proteins: The case of aplysia myoglobin
Tyrosine residues can act as redox cofactors that provide an electron transfer ("hole-hopping") route that enhances the rate of ferryl heme iron reduction by externally added reductants, for example, ascorbate. Aplysia fasciata myoglobin, having no naturally occurring tyrosines but 15 phenylalanines that can be selectively mutated to tyrosine residues, provides an ideal protein with which to study such through-protein electron transfer pathways and ways to manipulate them. Two surface exposed phenylalanines that are close to the heme have been mutated to tyrosines (F42Y, F98Y). In both of these, the rate of ferryl heme reduction increased by up to 3 orders of magnitude. This result cannot be explained in terms of distance or redox potential change between donor and acceptor but indicates that tyrosines, by virtue of their ability to form radicals, act as redox cofactors in a new pathway. The mechanism is discussed in terms of the Marcus theory and the specific protonation/deprotonation states of the oxoferryl iron and tyrosine. Tyrosine radicals have been observed and quantified by EPR spectroscopy in both mutants, consistent with the proposed mechanism. The location of each radical is unambiguous and allows us to validate theoretical methods that assign radical location on the basis of EPR hyperfine structure. Mutation to tyrosine decreases the lipid peroxidase activity of this myoglobin in the presence of low concentrations of reductant, and the possibility of decreasing the intrinsic toxicity of hemoglobin by introduction of these pathways is discussed. © 2012 American Chemical Society
On the geometry of mixed states and the Fisher information tensor
In this paper, we will review the co-adjoint orbit formulation of finite
dimensional quantum mechanics, and in this framework, we will interpret the
notion of quantum Fisher information index (and metric). Following previous
work of part of the authors, who introduced the definition of Fisher
information tensor, we will show how its antisymmetric part is the pullback of
the natural Kostant-Kirillov-Souriau symplectic form along some natural
diffeomorphism. In order to do this, we will need to understand the symmetric
logarithmic derivative as a proper 1-form, settling the issues about its very
definition and explicit computation. Moreover, the fibration of co-adjoint
orbits, seen as spaces of mixed states, is also discussed.Comment: 27 pages; Accepted Manuscrip
Population genetic analysis of the Plasmodium falciparum 6-cys protein Pf38 in Papua New Guinea reveals domain-specific balancing selection
<p>Abstract</p> <p>Background</p> <p>The <it>Plasmodium falciparum </it>merozoite surface protein Pf38 is targeted by antibodies of malaria immune adults and has been shown to be under balancing (immune) selection in a Gambian parasite population, indicating potential as a malaria vaccine candidate. This study explores the population genetics of <it>Pf</it>38 in Papua New Guinea, to determine the extent and geographic distribution of diversity and to measure selective pressure along the length of the gene.</p> <p>Methods</p> <p>Using samples collected during community-based cross-sectional surveys in the Mugil and Wosera regions, the <it>Pf38 </it>genes of 59 <it>P. falciparum </it>isolates were amplified and sequenced. These sequences, along with previously sequenced Gambian and laboratory isolates, were then subjected to an array of population genetic analyses, examining polymorphisms, haplotype diversity and balancing selection. In addition to whole-gene analysis, the two 6-cys domains were considered separately, to investigate domain specific polymorphism and selection.</p> <p>Results</p> <p>Nineteen polymorphic sites were identified in the <it>Pf </it>38 gene. Of these, 13 were found in the Gambia, 10 in Mugil and 8 in Wosera. Notably, the majority of common polymorphisms were confined to domain I. Although only moderate levels of nucleotide diversity were observed, the haplotype diversity was high in all populations, suggesting extensive recombination. Analyses of the full-length sequence provided only modest evidence for balancing selection. However, there was a strong contrast between domain I, which showed strong evidence for positive balancing selection, and domain II which was neutral. Analyses of the geographic distribution of Pf38 haplotypes showed that four haplotypes accounted for the majority of sequences found world-wide, but there were many more haplotypes unique to the African than the PNG populations.</p> <p>Conclusion</p> <p>This study confirmed previous findings that <it>Pf38 </it>is a polymorphic gene under balancing selection. However, analysing polymorphism and selection across the length of the gene painted a considerably different picture. Domain I is highly polymorphic and the target of significant balancing selection. In contrast, domain II is relatively conserved and does not show evidence of immune selective pressure. The findings have implications for future population genetic studies on vaccine candidates, showing that the biological context must also be considered as a framework for analysis.</p
On the elliptic nonabelian Fourier transform for unipotent representations of p-adic groups
In this paper, we consider the relation between two nonabelian Fourier
transforms. The first one is defined in terms of the Langlands-Kazhdan-Lusztig
parameters for unipotent elliptic representations of a split p-adic group and
the second is defined in terms of the pseudocoefficients of these
representations and Lusztig's nonabelian Fourier transform for characters of
finite groups of Lie type. We exemplify this relation in the case of the p-adic
group of type G_2.Comment: 17 pages; v2: several minor corrections, references added; v3:
corrections in the table with unipotent discrete series of G
Oncology providers' perspectives on endocrine therapy prescribing and management.
Adjuvant endocrine therapy (ET) can reduce the risk of recurrence among females with hormone receptor-positive breast cancer. Overall, initiation and adherence to ET are suboptimal, though reasons are not well described. The study's objective was to better understand ET decision making, prescribing, and patient management from oncology providers' perspectives. Using purposive sampling, we recruited oncology providers who saw five or more breast cancer patients per week (n=20). We conducted 30-45-minute telephone interviews, using a semistructured guide to elicit perspectives on ET use. We used thematic content analysis to systematically identify categories of meaning and double-coded transcripts using Atlas.ti. Providers recommend ET to all eligible patients except those with contraindications or other risk factors. Providers base their ET prescribing decisions on the patient's menopausal status, side effects, and comorbidities. ET is typically discussed multiple times: at the onset of breast cancer treatment and in more detail after other treatment completion. Providers felt that the associated recurrence risk reduction is the most compelling argument for patients during ET decision making. While providers rarely perceived noninitiation as a problem, nonadherence was prevalent, often due to unresolvable side effects. From the clinicians' perspectives, side effects from ET are the dominant factor in nonadherence. Efforts to improve adherence should focus on strategies to minimize side effects and ensure clinicians and patients are well informed regarding optimal side effect management. This finding has important implications for novel endocrine regimens that offer improved outcomes through longer duration or more intensive therapy
Understanding racial differences in health-related quality of life in a population-based cohort of breast cancer survivors
Although racial disparities in health-related quality of life (HRQOL) among women with breast cancer (BC) are well documented, less is known about HRQOL changes over time among women of different races. Our objective was to assess racial differences in HRQOL during active treatment and survivorship phases of BC care
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