Use of hyperpolarized [1-C]pyruvate and [2-C]pyruvate to probe the effects of the anticancer agent dichloroacetate on mitochondrial metabolism in vivo in the normal rat

Development of hyperpolarized technology utilizing dynamic nuclear polarization has enabled the measurement of ¹³C metabolism in vivo at very high signal-to-noise ratio (SNR). In vivo mitochondrial metabolism can, in principle, be monitored with pyruvate, which is catalyzed to acetyl-CoA via pyruvate dehydrogenase (PDH). The purpose of this work was to determine whether the compound sodium dichloroacetate (DCA) could aid the study of mitochondrial metabolism with hyperpolarized pyruvate. DCA stimulates PDH by inhibiting its inhibitor, pyruvate dehydrogenase kinase. In this work, hyperpolarized [1-¹³C]pyruvate and [2-¹³C]pyruvate were used to probe mitochondrial metabolism in normal rats. Increased conversion to bicarbonate (+ 181±69%, P=.025) was measured when [1-¹³C]pyruvate was injected after DCA administration, and increased glutamate (+ 74±23%, P=.004), acetoacetate (+ 504±281%, P=.009) and acetylcarnitine (+ 377±157%, P=.003) were detected when [2-¹³C]pyruvate was used.     

Probing reoxidation sites by in situ Raman spectroscopy: differences between reduced CeO2 and Pt/CeO2

Raman spectroscopy is a powerful technique for detecting peroxo (O₂)^2– and superoxo (O₂)^– species adsorbed on defect sites of ceria. These sites are probed by reducing CeO₂ at high temperature and then chemisorbing oxygen species at low temperature. In the present study, it is shown for the first time that such Raman characterization has to be achieved at very low laser power to avoid formation of oxygen species by photolysis and analyze only the chemisorbed species. Respecting this requirement, the (O₂)^2– and (O₂)^– species formed on 0.7% Pt/CeO₂ compound, and the CeO₂ support used to prepare it were compared after reduction for various times and at various temperatures. Superoxo species were more stabilized on reduced 0.7% Pt/CeO₂ after short reduction at 773 K than on reduced CeO₂. Additionally, the distributions of peroxo species adsorbed on defect sites of Pt/CeO₂ and CeO₂ were significantly different after long reduction at 773 K in spite of similar amounts. Indeed, less stable species were formed during the reduction of 0.7% Pt/CeO_2. These two features revealed that new sites were created during the preparation and reduction of Pt/CeO₂ compared to its bare support. Copyright © 2012 John Wiley & Sons, Ltd.     

Uptake of Europium(III) from Water using Magnetite Nanoparticles

It is demonstrated that colloidal magnetite nanoparticles can be used as nanosorbents for lanthanide ions dissolved in water. In particular, a series of experiments are performed for the removal of Eu(III) in distinct analytical conditions and by applying an external magnet to collect the sorbents previously dispersed in water samples. Furthermore, strategies for surface chemistry functionalization are also investigated, aiming to investigate the effect of this parameter on the removal capacity of the Fe₃O₄ nanoparticles. The supernatant solutions are monitored for the remaining amount of Eu(III) by fluorescence emission measurements in the presence of 2,6‐pyridinedicarboxylic acid as a sensitizer. The results demonstrate that neat Fe₃O₄ nanoparticles are capable of capturing lanthanide ions (III) from aqueous solutions (pH 7), without need of surface modification, and for subsequent removal by magnetic separation. During the removal, efficiency is increased after modifying the particles' surfaces with silica and 3‐aminopropyltrimethoxysilane; in alkaline medium (pH 10), there is complete removal regardless the type of nanosorbent used. This has been explained by the formation of insoluble Eu(III) species that adsorb strongly to the nanosorbents surfaces allowing their subsequent magnetic separation.     

Improved growth of solution‐deposited thin films on polycrystalline Cu(In,Ga)Se2

CdS and Zn(O,S) grown by chemical bath deposition (CBD) are well established buffer materials for Cu(In,Ga)Se₂ (CIGS) solar cells. As recently reported, a non‐contiguous coverage of CBD buffers on CIGS grains with {112} surfaces can be detected, which was explained in terms of low surface energies of the {112} facets, leading to deteriorated wetting of the chemical solution on the CIGS surface. In the present contribution, we report on the effect of air annealing of CIGS thin films prior to the CBD of CdS and Zn(O,S) layers. In contrast to the growth on the as‐grown CIGS layers, these buffer lay‐ ers grow densely on the annealed CIGS layer, even on grains with {112} surfaces. We explain the different growth behavior by increased surface energies of CIGS grains due to the annealing step, i.e., due to oxidation of the CIGS surface. Reference solar cells were processed and completed by i‐ZnO/ZnO:Al layers for CdS and by (Zn,Mg)O/ZnO:Al for Zn(O,S) buffers. For solar cells with both, CdS and Zn(O,S) buffers, air‐annealed CIGS films with improved buffer coverage resulted in higher power‐conversion efficiencies, as compared with the devices containing as‐grown CIGS layers. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Affine compact almost-homogeneous manifolds of cohomogeneity one

This paper is one in a series generalizing our results in [12, 14, 15, 20] on the existence of extremal metrics to the general almost-homogeneous manifolds of cohomogeneity one. In this paper, we consider the affine cases with hypersurface ends. In particular, we study the existence of Kähler-Einstein metrics on these manifolds and obtain new Kähler-Einstein manifolds as well as Fano manifolds without Kähler-Einstein metrics. As a consequence of our study, we also give a solution to the problem posted by Ahiezer on the nonhomogeneity of compact almost-homogeneous manifolds of cohomogeneity one; this clarifies the classification of these manifolds as complex manifolds. We also consider Fano properties of the affine compact manifolds.     

Gaps in the number of generators of monomial Togliatti systems

Let $I_{d,n}?k[x_0,?,x_n]$ be a minimal monomial Togliatti system of forms of degree d. In [4], Mezzetti and Miró-Roig proved that the minimal number of generators $\mu (I_{d,n})$ of $I_{d,n}$ lies in the interval $[2n+1,\left(\begin{array}{c}n+d?1\\ n?1\end{array}\right)]$. In this paper, we prove that for $n\ge 4$ and $d\ge 3$, the integer values in $[2n+3,3n?1]$ cannot be realized as the number of minimal generators of a minimal monomial Togliatti system. We classify minimal monomial Togliatti systems $I_{d,n}?k[x_0,?,x_n]$ of forms of degree d with $\mu (I_{d,n})=2n+2$ or 3n (i.e. with the minimal number of generators reaching the border of the non-existence interval). Finally, we prove that for $n=4$, $d\ge 3$ and $\mu \in [9,\left(\begin{array}{c}d+3\\ 3\end{array}\right)]?\{11\}$ there exists a minimal monomial Togliatti system $I_{d,n}?k[x_0,?,x_n]$ of forms of degree d with $\mu (I_{n,d})=\mu$.     

On the Positivity of the Coefficients of a Certain Polynomial Defined by Two Positive Definite Matrices

It is shown that the polynomialp(t) = Tr[(A+tB)^m]has positive coefficients when m = 6 and A and B are any two 3-by-3 complex Hermitian positive definite matrices. This case is the first that is not covered by prior, general results. This problem arises from a conjecture raised by Bessis, Moussa, and Villani in connection with a long-standing problem in theoretical physics. The full conjecture, as shown recently by Lieb and Seiringer, is equivalent to p(t) having positive coefficients for any m and any two n-by-n positive definite matrices. We show that, generally, the question in the real case reduces to that of singular A and B, and this is a key part of our proof.     

T2-shortening of 3He gas by magnetic microspheres

In a gas-filled material like the lung parenchyma, the transverse relaxation time (T2) for 3He is shortened by the deposition of magnetic microspheres and rapid molecular diffusion through induced field distortions. Here, this unique relaxation process is described theoretically and predicted T2-shortening is validated using pressurized 3He gas in a foam model of alveolar airways. Results demonstrate that: (1) significant T2-shortening is induced by microsphere deposition, (2) shortened 3He T2s are accurately predicted, and (3) measured relaxation times are exploitable for quantifying local deposition patterns. Based on these findings the feasibility of imaging inhaled particulates in vivo with hyperpolarized 3He is examined and performance projections are formulated.     

Voice responses to changes in pitch of voice or tone auditory feedback

The present study was undertaken to examine if a subject's voice F0 responded not only to perturbations in pitch of voice feedback but also to changes in pitch of a side tone presented congruent with voice feedback. Small magnitude brief duration perturbations in pitch of voice or tone auditory feedback were randomly introduced during sustained vowel phonations. Results demonstrated a higher rate and larger magnitude of voice F0 responses to changes in pitch of the voice compared with a triangular-shaped tone (experiment 1) or a pure tone (experiment 2). However, response latencies did not differ across voice or tone conditions. Data suggest that subjects responded to the change in F0 rather than harmonic frequencies of auditory feedback because voice F0 response prevalence, magnitude, or latency did not statistically differ across triangular-shaped tone or pure-tone feedback. Results indicate the audio-vocal system is sensitive to the change in pitch of a variety of sounds, which may represent a flexible system capable of adapting to changes in the subject's voice. However, lower prevalence and smaller responses to tone pitch-shifted signals suggest that the audio-vocal system may resist changes to the pitch of other environmental sounds when voice feedback is present.     

Quantitative pharmacokinetic analysis of DCE-MRI data without an arterial input function: a reference region model

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) can assess tumor perfusion, microvascular vessel wall permeability and extravascular-extracellular volume fraction. Analysis of DCE-MRI data is usually based on indicator dilution theory that requires knowledge of the concentration of the contrast agent in the blood plasma, the arterial input function (AIF). A method is presented that compares the tissues of interest (TOI) curve shape to that of a reference region (RR), thereby eliminating the need for direct AIF measurement. By assigning literature values for Ktrans (the blood perfusion-vessel permeability product) and v(e) (extravascular-extracellular volume fraction) in a reference tissue, it is possible to extract the Ktrans and v(e) values for a TOI without knowledge of the AIF. The operational RR equation for DCE-MRI analysis is derived, and its sensitivity to noise and incorrect assignment of the RR parameters is tested via simulations. The method is robust at noise levels of 10%, returning accurate (+/-20% in the worst case) and precise (+/-15% in the worst case) values. Errors in the TOI Ktrans and v(e) values scale approximately linearly with the errors in the assigned RR Ktrans and v(e) values. The methodology is then applied to a Lewis Lung Carcinoma mouse tumor model. A slowly enhancing TOI yielded Ktrans=0.039+/-0.002 min-1 and v(e)=0.46+/-0.01, while a rapidly enhancing region yielded Ktrans=0.35+/-0.05 min-1 and v(e)=0.31+/-0.01. Parametric Ktrans and v(e) mappings manifested a tumor periphery with elevated Ktrans (>0.30 min-1) and v(e) (>0.30) values. The main advantage of the RR approach is that it allows for quantitative assessment of tissue properties without having to obtain high temporal resolution images to characterize an AIF. This allows for acquiring images with higher spatial resolution and/or SNR, and therefore, increased ability to probe tissue heterogeneity.