335 research outputs found
Human Papillomavirus and Oropharyngeal Squamous Cell Carcinoma: A Case-Control Study regarding Tobacco and Alcohol Consumption
We aimed to determine the role of HPV in the pathogenesis and outcome of oropharyngeal squamous cell carcinoma (OSCC) in lifelong nonsmoking and nondrinking patients. A case-case analysis was performed to compare the presence of HPV-DNA in tumor cells of 16 nonsmoking and nondrinking with 16 matched smoking and drinking patients (matching criteria: age at incidence, gender, tumor sublocation, tumor stage). HPV was detected using 2 PCR tests, FISH analysis, and p16INK4A immunostaining. Nonsmoking and nondrinking patients had more HPV-positive tumors than smoking and drinking patients (n = 12; 75% versus n = 2; 13%; P < 0.001). All HPV-positive tumors showed p16INK4A overexpression, and 1 HPV-negative tumor had p16INK4A overexpression, (P < 0.001). Overall survival and disease-specific survival were higher for HPV-positive compared to HPV-negative cases (P = 0.027, P = 0.039, resp.). In conclusion, HPV is strongly associated with OSCC of nonsmoking and nondrinking patients. Specific diagnostic and therapeutic actions should be considered for these patients to achieve a better prognosis
Measurements of the Casimir-Lifshitz force in fluids: the effect of electrostatic forces and Debye screening
In this work, we present detailed measurements of the Casimir-Lifshitz force
between two gold surfaces (a sphere and a plate) immersed in ethanol and study
the effect of residual electrostatic forces, which are dominated by static
fields within the apparatus and can be reduced with proper shielding.
Electrostatic forces are further reduced by Debye screening through the
addition of salt ions to the liquid. Additionally, the salt leads to a
reduction of the Casimir-Lifshitz force by screening the zero-frequency
contribution to the force; however, the effect is small between gold surfaces
at the measured separations and within experimental error. An improved
calibration procedure is described and compared to previous methods. Finally,
the experimental results are compared to Lifshitz's theory and found to be
consistent for the materials used in the experiment.Comment: 11 figures. PRA in pres
Improved Precision Measurement of the Casimir Force
We report an improved precision measurement of the Casimir force. The force
is measured between a large Al coated sphere and flat plate using an Atomic
Force Microscope. The primary experimental improvements include the use of
smoother metal coatings, reduced noise, lower systematic errors and independent
measurement of surface separations. Also the complete dielectric spectrum of
the metal is used in the theory. The average statistical precision remains at
the same 1% of the forces measured at the closest separation
Measurement of the Casimir force between parallel metallic surfaces
We report on the measurement of the Casimir force between conducting surfaces
in a parallel configuration. The force is exerted between a silicon cantilever
coated with chromium and a similar rigid surface and is detected looking at the
shifts induced in the cantilever frequency when the latter is approached. The
scaling of the force with the distance between the surfaces was tested in the
0.5 - 3.0 m range, and the related force coefficient was determined at the
15% precision level.Comment: 4 Figure
Casimir and van der Waals force between two plates or a sphere (lens) above a plate made of real metals
The Casimir and van der Waals forces acting between two metallic plates or a
sphere (lens) above a plate are calculated accounting for the finite
conductivity of the metals. The simple formalism of surface modes is briefly
presented which allows the possibility to obtain the generalization of Lifshitz
results for the case of two semi-spaces covered by the thin layers. Additional
clarifications of the regularization procedure provides the means to obtain
reliable results not only for the force but also for the energy density. This,
in turn, leads to the value of the force for the configuration of a sphere
(lens) above a plate both of which are covered by additional layers. The
Casimir interaction between Al and Au test bodies is recalculated using the
optical tabulated data for the complex refractive index of these metals. The
computations turn out to be in agreement with the perturbation theory up to the
fourth order in relative penetration depth of electromagnetic zero point
oscillations into the metal. The disagreements between the results recently
presented in the literature are resolved. The Casimir force between Al bodies
covered by the thin Au layers is computed and the possibility to neglect
spatial dispersion effects is discussed as a function the layer thickness. The
van der Waals force is calculated including the transition region to the
Casimir force. The pure non-retarded van der Waals force law between Al and Au
bodies is shown to be restricted to a very narrow distance interval from 0.5 nm
to (2--4) nm. New, more exact, values of the Hamaker constant for Al and Au are
determined.Comment: 5 figure
Identification of genetic variants that impact gene co-expression relationships using large-scale single-cell data
Background: Expression quantitative trait loci (eQTL) studies show how genetic variants affect downstream gene expression. Single-cell data allows reconstruction of personalized co-expression networks and therefore the identification of SNPs altering co-expression patterns (co-expression QTLs, co-eQTLs) and the affected upstream regulatory processes using a limited number of individuals. Results: We conduct a co-eQTL meta-analysis across four scRNA-seq peripheral blood mononuclear cell datasets using a novel filtering strategy followed by a permutation-based multiple testing approach. Before the analysis, we evaluate the co-expression patterns required for co-eQTL identification using different external resources. We identify a robust set of cell-type-specific co-eQTLs for 72 independent SNPs affecting 946 gene pairs. These co-eQTLs are replicated in a large bulk cohort and provide novel insights into how disease-associated variants alter regulatory networks. One co-eQTL SNP, rs1131017, that is associated with several autoimmune diseases, affects the co-expression of RPS26 with other ribosomal genes. Interestingly, specifically in T cells, the SNP additionally affects co-expression of RPS26 and a group of genes associated with T cell activation and autoimmune disease. Among these genes, we identify enrichment for targets of five T-cell-activation-related transcription factors whose binding sites harbor rs1131017. This reveals a previously overlooked process and pinpoints potential regulators that could explain the association of rs1131017 with autoimmune diseases. Conclusion: Our co-eQTL results highlight the importance of studying context-specific gene regulation to understand the biological implications of genetic variation. With the expected growth of sc-eQTL datasets, our strategy and technical guidelines will facilitate future co-eQTL identification, further elucidating unknown disease mechanisms.</p
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