Following solid-acid-catalyzed reactions by MAS NMR spectroscopy in liquid phase--zeolite-catalyzed conversion of cyclohexanol in water.

A microautoclave magic angle spinning NMR rotor is developed enabling in situ monitoring of solid-liquid-gas reactions at high temperatures and pressures. It is used in a kinetic and mechanistic study of the reactions of cyclohexanol on zeolite HBEA in 130 °C water. The (13) C spectra show that dehydration of 1-(13) C-cyclohexanol occurs with significant migration of the hydroxy group in cyclohexanol and the double bond in cyclohexene with respect to the (13) C label. A simplified kinetic model shows the E1-type elimination fully accounts for the initial rates of 1-(13) C-cyclohexanol disappearance and the appearance of the differently labeled products, thus suggesting that the cyclohexyl cation undergoes a 1,2-hydride shift competitive with rehydration and deprotonation. Concurrent with the dehydration, trace amounts of dicyclohexyl ether are observed, and in approaching equilibrium, a secondary product, cyclohexyl-1-cyclohexene is formed. Compared to phosphoric acid, HBEA is shown to be a more active catalyst exhibiting a dehydration rate that is 100-fold faster per proton.

Lactic acid is elevated in idiopathic pulmonary fibrosis and induces myofibroblast differentiation via pH-dependent activation of transforming growth factor-ß.

RATIONALE: Idiopathic pulmonary fibrosis (IPF) is a complex disease for which the pathogenesis is poorly understood. In this study, we identified lactic acid as a metabolite that is elevated in the lung tissue of patients with IPF. OBJECTIVES: This study examines the effect of lactic acid on myofibroblast differentiation and pulmonary fibrosis. METHODS: We used metabolomic analysis to examine cellular metabolism in lung tissue from patients with IPF and determined the effects of lactic acid and lactate dehydrogenase-5 (LDH5) overexpression on myofibroblast differentiation and transforming growth factor (TGF)-ß activation in vitro. MEASUREMENTS AND MAIN RESULTS: Lactic acid concentrations from healthy and IPF lung tissue were determined by nuclear magnetic resonance spectroscopy; α-smooth muscle actin, calponin, and LDH5 expression were assessed by Western blot of cell culture lysates. Lactic acid and LDH5 were significantly elevated in IPF lung tissue compared with controls. Physiologic concentrations of lactic acid induced myofibroblast differentiation via activation of TGF-ß. TGF-ß induced expression of LDH5 via hypoxia-inducible factor 1α (HIF1α). Importantly, overexpression of both HIF1α and LDH5 in human lung fibroblasts induced myofibroblast differentiation and synergized with low-dose TGF-ß to induce differentiation. Furthermore, inhibition of both HIF1α and LDH5 inhibited TGF-ß-induced myofibroblast differentiation. CONCLUSIONS: We have identified the metabolite lactic acid as an important mediator of myofibroblast differentiation via a pH-dependent activation of TGF-ß. We propose that the metabolic milieu of the lung, and potentially other tissues, is an important driving force behind myofibroblast differentiation and potentially the initiation and progression of fibrotic disorders.

Influence of Feeding Type and Nosema ceranae Infection on the Gut Microbiota of Apis cerana Workers.

The gut microbiota plays an essential role in the health of bees. To elucidate the effect of feed and Nosema ceranae infection on the gut microbiota of honey bee (Apis cerana), we used 16S rRNA sequencing to survey the gut microbiota of honey bee workers fed with sugar water or beebread and inoculated with or without N. ceranae. The gut microbiota of A. cerana is dominated by Serratia, Snodgrassella, and Lactobacillus genera. The overall gut microbiota diversity was show to be significantly differential by feeding type. N. ceranae infection significantly affects the gut microbiota only in bees fed with sugar water. Higher abundances of Lactobacillus, Gluconacetobacter, and Snodgrassella and lower abundances of Serratia were found in bees fed with beebread than in those fed with sugar water. N. ceranae infection led to a higher abundance of Snodgrassella and a lower abundance of Serratia in sugar-fed bees. Imputed bacterial Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways showed the significant metagenomics functional differences by feeding and N. ceranae infections. Furthermore, A. cerana workers fed with sugar water showed lower N. ceranae spore loads but higher mortality than those fed with beebread. The cumulative mortality was strongly positive correlated (rho = 0.61) with the changes of overall microbiota dissimilarities by N. ceranae infection. Both feeding types and N. ceranae infection significantly affect the gut microbiota in A. cerana workers. Beebread not only provides better nutrition but also helps establish a more stable gut microbiota and therefore protects bees in response to N. ceranae infection. IMPORTANCE The gut microbiota plays an essential role in the health of bees. Scientific evidence suggests that diet and infection can affect the gut microbiota and modulate the health of the gut; however, the interplay between those two factors and the bee gut microbiota is not well known. In this study, we used a high-throughput sequencing method to monitor the changes of gut microbiota associated with both feeding types and Nosema ceranae infection. Our results showed that the gut microbiota composition and diversity of Asian honey bee were significantly associated with both feeding types and the N. ceranae infection. More interestingly, bees fed with beebread showed higher microbiota stability and lower mortality rates than those fed with sugar water when infected by N. ceranae. Those data suggest that beebread has the potential not only to provide better nutrition but also help to establish a more stable gut microbiota to protect bees against N. ceranae infection.

Slow-MAS NMR: A new technology for in vivo metabolomic studies.

Obtaining detailed in vivo metabolic information has been identified as key elements of better understanding the efficacy and toxicity of new therapies. A new nuclear magnetic resonance (NMR) technology called LOCMAT is reported in this paper that yields substantially increased spectral resolution in spatially localized in vivo H NMR metabolite spectra, as illustrated by measurements in the liver of a live mouse. LOCMAT promises to significantly enhance the utility of NMR spectroscopy for biomedical research.:

Localized in vivo isotropic-anisotropic correlation 1H NMR spectroscopy using ultraslow magic angle spinning.

In a previous work (1), the susceptibility broadening in the (1)H NMR metabolite spectrum obtained in a live mouse was separated from the isotropic information, which significantly increased the spectral resolution. This was achieved using ultraslow magic angle spinning (MAS) of the animal combined with a modified phase-corrected magic angle turning (PHORMAT) pulse sequence. However, PHORMAT cannot be used for spatially selective spectroscopy. This article introduces a modified sequence called localized magic angle turning (LOCMAT) that makes this possible. Proton LOCMAT spectra were obtained from the liver and heart of a live mouse while the animal was spun at a speed of 4 Hz in a 2 Tesla field. It was found that even in this relatively low field, LOCMAT provided isotropic line widths that were a factor of 4-10 times smaller than those obtained in a stationary animal. Furthermore, the susceptibility broadening of the heart metabolites showed unusual features that are not observed in dead animals. The limitations of LOCMAT and possible ways to improve the technique are discussed. It is concluded that in vivo LOCMAT can significantly enhance the utility of NMR spectroscopy for biomedical research.

Stereochemical analysis by solid-state NMR: structural predictions in ambuic acid.

Relative stereochemistry is predicted for ambuic acid using a novel solid-state NMR approach. This NMR technique entails a comparison of measured shift tensor principal values with computed values for all diastereomers, allowing the selection of a best-fit structure. The proposed method extends previous solution NMR structural data by simultaneously modeling with high statistical probability hydrogen-bonding arrangements and molecular conformation at two positions. A dimeric structure is proposed for ambuic acid based on the initial poor fit of the carboxyl carbon tensors to a monomeric model. The dimer model, consisting of hydrogen bonding between pairs of neighboring carboxyl groups, reduces the root mean square error at the carboxy tensor by a factor of 2.7. Lattice details are thus also described by the proposed approach. The structural characterization method presented is of general applicability and may be especially useful for characterizing difficult to crystallize or hydrogen-poor materials.