Significance: Decline in NAD ⁺ availability and abnormal NAD ⁺ /NADH redox state are tightly linked to age-related metabolic diseases and neurodegenerative disorders. To better understand the roles of NAD metabolism and redox state in health and disease, it is important to assess the intracellular NAD and redox state in situ. We report herein the first in vivo NAD assay, to our knowledge, that is capable of noninvasively and simultaneously measuring intracellular NAD ⁺ and NADH concentrations and NAD ⁺ /NADH ratio in the human brain and detecting the age-dependent changes in NAD contents and redox state associated with the normal aging. This method can potentially be applied to study various metabolic and neurodegenerative disorders by monitoring the NAD and redox state changes associated with disease progression or treatment in human patients.

A highly self-textured Ga₂O₃-substituted Li₇La₃Zr₂O₁₂ (LLZO-Ga) solid electrolyte with a nominal composition of Li_6.55Ga_0.15La₃Zr₂O₁₂ is obtained by a simple and low-cost solid-state reaction technique, requiring no seed crystals to achieve grain orientation. The as-prepared self-textured LLZO-Ga shows a strong (420) preferred orientation with a high Lotgering factor of 0.91. Coherently, a terrace-shaped microstructure consisting of many parallel layers, indicating a two-dimensional-like growth mode, is clearly observed in the self-textured sample. As a result, the highly self-textured garnet-type lithium-ion conducting solid electrolyte of LLZO-Ga exhibits an extremely high ionic conductivity, reaching a state-of-the-art level of 2.06 × 10⁻³ S cm⁻¹ at room temperature (25 °C) and thus shedding light on an important strategy for improving the structure and ionic conductivity of solid electrolytes.

Purpose: Nicotinamide adenine dinucleotide (NAD), in oxidized (NAD⁺) or reduced (NADH) form, plays key roles in cellular metabolism. Intracellular NAD⁺/NADH ratio represents the cellular redox state; however, it is difficult to measure in vivo. We report here a novel in vivo ³¹P MRS method for noninvasive measurement of intracellular NAD concentrations and NAD⁺/NADH ratio in the brain.Methods: It uses a theoretical model to describe the NAD spectral patterns at a given field for quantification. Standard NAD solutions and independent cat brain measurements at 9.4 T and 16.4 T were used to evaluate this method. We also measured T₁ values of brain NAD.Results: Model simulation and studies of solutions and brains indicate that the proposed method can quantify submillimolar NAD concentrations with reasonable accuracy if adequate ³¹P MRS signal‐to‐noise ratio and linewidth were obtained. The NAD concentrations and NAD⁺/NADH ratio of cat brains measured at 16.4 T and 9.4 T were consistent despite the significantly different T₁ values and NAD spectra patterns at two fields.Conclusion: This newly established ³¹P MRS method makes it possible for the first time to noninvasively study the intracellular redox state and its roles in brain functions and diseases, and it can potentially be applied to other organs. Magn Reson Med 71:1959–1972, 2014. © 2013 Wiley Periodicals, Inc.