540 research outputs found
Linear bound for the dyadic paraproduct on weighted Lebesgue space
The dyadic paraproduct is bounded in weighted Lebesgue spaces if and
only if the weight belongs to the Muckenhoupt class . However, the
sharp bounds on the norm of the dyadic paraproduct are not known even in the
simplest case. In this paper we prove the linear bound on the norm of
the dyadic paraproduct in the weighted Lebesgue space using Bellman
function techniques and extrapolate this result to the case.Comment: 13 page
Influence of Chlorinating Agents on the Formation of Stable Biomarkers in Hair for the Retrospective Verification of Exposure
Chlorine, as a dual-use chemical, is an essential industrial chemical which has been used as a chemical weapon in the past due to its toxicity and availability. The retrospective verification of chlorine intoxication is often especially challenging, and unambiguous markers are still missing. In this study, the effects of different chlorinating and oxidizing agents on human hair were investigated. Samples were exposed to a variety of chlorinating chemicals for a short time and then completely hydrolyzed by a HBr solution to break down their keratin proteins into individual amino acids. After derivatization and targeted liquid chromatography-mass spectrometry analysis, 3-chlorotyrosine and 3,5-dichlorotyrosine were unambiguously identified from human hair exposed to chlorine, hypochlorite, and sulfuryl chloride. Our results show long-term stability of these markers in the biological matrix, as the chlorotyrosines can still be found 10 months post-exposure at the same levels. Finally, an untargeted analysis was able to discriminate between some of the different intoxicants
Effect of a selenium-deficient diet on blood values of T3 and T4 in cows
Pastures in the south of Chile have been shown to be selenium deficient, and as selenium is a component of deiodinase type 1, which is necessary for the synthesis of triiodothyronine (T3) at peripheral levels, the effect of selenium deficiency on the blood concentration of theses hormones in cows was studied. Twelve pregnant Friesian cows were randomly allocated into two homogeneous groups of six animals each-selenium supplemented and selenium deficient. The selenium deficient diet consisted of 11.5 kg of hay, 500 g of soya bran, 150 g of mineral mix (without selenium), 500 g of fat for animal feeding, and was given from day 15 of lactation until the end of the study. A commercial concentrate (Cosetan) and urea was also given according to lactation requirements (up to 5 kg and up to 120 g, respectively). The selenium content was 0.05 ppm of dry matter (equivalent to 18% of the daily requirements). The supplemented group was injected subcutaneously with 1 mg Se/kg, using the commercial product Deposel (1 ml/50kg). Blood samples were obtained by coccygeous vein venepuncture before supplementation (prepartum basal values) and thereafter every 15 days. GSH-Px activity in plasma was measured using a HITACHI 4020 spectrophotometer. Serum T3 and thyroxine (T4) concentrations were measured by electrochemiluminiscence. ANOVA, Tuckey test and Student's t-test were used to establish the significance of the intra group differences, with p = < 0.05 being considered significant. There were no significant differences in blood values of T4 in either the supplemented or non-supplemented groups during pregnancy and lactation. However the blood values of T4 decreased significantly (p = < 0.05) during days 30-60 of lactation to values below the reference range. The T3 serum concentrations in the supplemented group of cows were significantly lower (p = < 0.05) at 60, 90 and 150 days of lactation than cows that had been supplemented with selenium
Impact of cerebral hypoperfusion-reperfusion on optic nerve integrity and visual function in the DBA/2J mouse model of glaucoma.
OBJECTIVE
One of the most important risk factors for developing a glaucomatous optic neuropathy is elevated intraocular pressure. Moreover, mechanisms such as altered perfusion have been postulated to injure the optical path. In a mouse model, we compare first negative effects of cerebral perfusion/reperfusion on the optic nerve structure versus alterations by elevated intraocular pressure. Second, we compare the alterations by isolated hypoperfusion-reperfusion and isolated intraocular pressure to the combination of both.
METHODS AND ANALYSIS
Mice were divided in four groups: (1) controls; (2) perfusion altered mice that underwent transient bi-common carotid artery occlusion (BCCAO) for 40 min; (3) glaucoma group (DBA/2J mice); (4) combined glaucoma and altered perfusion (DBA/2J mice with transient BCCAO). Optic nerve sections were stereologically examined 10-12 weeks after intervention.
RESULTS
All experimental groups showed a decreased total axon number per optic nerve compared with controls. In DBA/2J and combined DBA/2J & BCCAO mice the significant decrease was roughly 50%, while BCCAO leaded to a 23% reduction of axon number, however reaching significance only in the direct t-test. The difference in axon number between BCCAO and both DBA/2J mice was almost 30%, lacking statistical significance due to a remarkably high variation in both DBA/2J groups.
CONCLUSION
Elevated intraocular pressure in the DBA/2J mouse model of glaucoma leads to a much more pronounced optic nerve atrophy compared with transient forebrain hypoperfusion and reperfusion by BCCAO. A supposed worsening effect of an altered perfusion added to the pressure-related damage could not be detected
A Kerr Polarization Controller
Kerr-effect-induced changes of the polarization state of light are well known in pulsed laser systems. An example is nonlinear polarization rotation, which is critical to the operation of many types of mode-locked lasers. Here, we demonstrate that the Kerr effect in a high-finesse Fabry-Pérot resonator can be utilized to control the polarization of a continuous wave laser. It is shown that a linearly-polarized input field is converted into a left- or right-circularly-polarized field, controlled via the optical power. The observations are explained by Kerr-nonlinearity induced symmetry breaking, which splits the resonance frequencies of degenerate modes with opposite polarization handedness in an otherwise symmetric resonator. The all-optical polarization control is demonstrated at threshold powers down to 7 mW. The physical principle of such Kerr effect-based polarization controllers is generic to high-Q Kerr-nonlinear resonators and could also be implemented in photonic integrated circuits. Beyond polarization control, the spontaneous symmetry breaking of polarization states could be used for polarization filters or highly sensitive polarization sensors when operated close to the symmetry-breaking point
Estatus de selenio en equinos Criollo-Chileno a pastoreo y su respuesta a la suplementación
RESUMEN
Objetivo. Dos experimentos se realizaron para determinar el estatus de selenio en equinos Criollo-Chileno a pastoreo y, evaluar la respuesta a la suplementación con Na2SeO3. Materiales y métodos. Exp.1A caballos pertenecientes a 10 criaderos del sur de Chile se les determinó la actividad sanguínea de glutatión peroxidasa (GPx, EC.1.11.1.9) (AcGPx). Los animales pertenecieron a 3 grupos, pastoreo de otoño (PO, n=40), pastoreo de otoño y suplementados con avena (PO+A, n=47), y, pastoreo de primavera (PP, n=41). Exp2Se utilizaron equinos con carencia de selenio, distribuidos en tres grupos: G1, n=7, tratado con Na2SeO3 el día 0 (Se= 0.05 mg/kg pv, im); G2, n=8, suplementado con Na2SeO3, los días 0 y 15 y GC, n=8, control. La AcGPx se determinó al día 0, 30 y 120. Resultados. La mediana (Me) de la AcGPx en todos los grupos fue menor al límite adecuado (>130 U/gHb), mayor en PO+A (Me=92, P25%=47, P75%=129 U/gHb) y PP (Me=85, P25%=45, P75%=114 U/gHb) que en PO (Me=35, P25%=20, P75%=85 U/gHb) (p<0.05). En el experimento 2 la AcGPx fue similar y menor al adecuado en todos los grupos. La suplementación con Na2SeO3 aumentó (p<0.05) la AcGPx en G1 (121±52 U/gHb) y G2 (124±69 U/gHb), sin alcanzar valores adecuados. Conclusiones. Los equinos Criollo-Chileno a pastoreo en el sur de Chile presentan carencia de Se, mayor en otoño que primavera y menor al suplementar con avena. Adicionalmente, la administración parenteral de Na2SeO3 mejora el estatus de Se, pero sin revertir el cuadro carencial
Scaling of the Critical Function for the Standard Map: Some Numerical Results
The behavior of the critical function for the breakdown of the homotopically
non-trivial invariant (KAM) curves for the standard map, as the rotation number
tends to a rational number, is investigated using a version of Greene's residue
criterion. The results are compared to the analogous ones for the radius of
convergence of the Lindstedt series, in which case rigorous theorems have been
proved. The conjectured interpolation of the critical function in terms of the
Bryuno function is discussed.Comment: 26 pages, 3 figures, 13 table
The MIQE Guidelines: Minimum Information for Publication of Quantitative Real-Time PCR Experiments
BACKGROUND: Currently, a lack of consensus exists on how best to perform and interpret quantitative real-time PCR (qPCR) experiments. The problem is exacerbated by a lack of sufficient experimental detail in many publications, which impedes a reader's ability to evaluate critically the quality of the results presented or to repeat the experiments. CONTENT: The Minimum Information for Publication of Quantitative Real-Time PCR Experiments (MIQE) guidelines target the reliability of results to help ensure the integrity of the scientific literature, promote consistency between laboratories, and increase experimental transparency. MIQE is a set of guidelines that describe the minimum information necessary for evaluating qPCR experiments. Included is a checklist to accompany the initial submission of a manuscript to the publisher. By providing all relevant experimental conditions and assay characteristics, reviewers can assess the validity of the protocols used. Full disclosure of all reagents, sequences, and analysis methods is necessary to enable other investigators to reproduce results. MIQE details should be published either in abbreviated form or as an online supplement. SUMMARY: Following these guidelines will encourage better experimental practice, allowing more reliable and unequivocal interpretation of qPCR results
Improved non-invasive positron emission tomographic imaging of chemotherapy-induced tumor cell death using Zirconium-89-labeled APOMAB®
Purpose: The chimeric monoclonal antibody (mAb) chDAB4 (APOMAB®) targets the Lupus associated (La)/Sjögren Syndrome-B (SSB) antigen, which is over-expressed in tumors but only becomes available for antibody binding in dead tumor cells. Hence, chDAB4 may be used as a novel theranostic tool to distinguish between responders and nonresponders early after chemotherapy. Here, we aimed to ascertain which positron emitter, Zirconium-89 ([⁸⁹Zr]Zr(IV)) or Iodine-124 ([¹²⁴I]I), was best suited to label chDAB4 for post-chemotherapy PET imaging of tumor-bearing mice and to determine which of two different bifunctional chelators provided optimal tumor imaging by PET using [⁸⁹Zr]Zr(IV)-labeled chDAB4. Methods: C57BL/6 J mice bearing subcutaneous syngeneic tumors of EL4 lymphoma were either untreated or given chemotherapy, then administered radiolabeled chDAB4 after 24 h with its biodistribution examined using PET and organ assay. We compared chDAB4 radiolabeled with [⁸⁹Zr] Zr(IV) or [¹²⁴I] I, or [⁸⁹Zr]Zr-chDAB4 using either DFO-NCS or DFOSq as a chelator. Results: After chemotherapy, [⁸⁹Zr]Zr-chDAB4 showed higher and prolonged mean (± SD) tumor uptake of 29.5 ± 5.9 compared to 7.8 ± 1.2 for [¹²⁴I] I -chDAB4. In contrast, antibody uptake in healthy tissues was not affected. Compared to DFO-NCS, DFOSq did not result in significant differences in tumor uptake of [⁸⁹Zr]Zr-chDAB4 but did alter the tumor:liver ratio in treated mice 3 days after injection in favour of DFOSq (8.0 ± 1.1) compared to DFO-NCS (4.2 ± 0.7). Conclusion: ImmunoPET using chDAB4 radiolabeled with residualizing [⁸⁹Zr] Zr(IV) rather than [¹²⁴I] I optimized post-chemotherapy tumor uptake. Further, PET imaging characteristics were improved by DFOSq rather than DFO-NCS. Therefore, the radionuclide/chelator combination of [⁸⁹Zr] Zr(IV) and DFOSq is preferred for the imminent clinical evaluation of chDAB4 as a selective tumor cell death radioligand.Vasilios Liapis, William Tieu, Stacey E. Rudd, Paul S. Donnelly, Nicole L. Wittwer, Michael P. Brown, and Alexander H. Staudache
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