Thermally processed diets are widely consumed, although advanced-glycation end products (AGEs) are unavoidably formed. AGEs, clusters of protein-cross-linking products, become less digestible because they impair intestinal peptidase proteolysis. We characterized the impacts of dietary AGEs on gut microbiota through a microbiome-to-metabolome association study. C57BL/6 mice were fed a heat-treated diet (high-AGE diet, H-AGE) or a standard AIN-93G diet (low-AGE diet, L-AGE) for 8 months. Fecal-microbiota composition was examined by 16S rDNA sequencing, and fecal-metabolome profile was evaluated by gas chromatography-tandem time-of-flight mass spectrometry (GC-TOF-MS). Reduced α-diversity and altered microbiota composition with elevated Helicobacter levels were found in the H-AGE group, and among the 57 perturbed metabolites, protein-fermentation products (i.e., p-cresol and putrescine) were increased. Major dysfunctional metabolic pathways were associated with carbohydrate and amino acid metabolism in two groups. Moreover, high correlations were found between fluctuant gut microbiota and metabolites. These findings might reveal the underlying mechanisms of the detrimental impacts of dietary AGEs on host health.
Metal-organic frameworks (MOFs) as new classes of proton-conducting materialsh ave been highlighted in recent years. Nevertheless, the exploration of proton-conducting MOFs as formic acid sensors is extremelyl acking. Herein, we prepared two highly stable 3D isostructurall anthanide(III) MOFs, {(M(m 3 -HPhIDC)(m 2 -C 2 O 4 ) 0.5 (H 2 O))·2 H 2 O} n (M = Tb (ZZU-1); Eu (ZZU-2)) (H 3 PhIDC = 2-phenyl-1H-imidazole-4,5-dicarboxylic acid), in which the coordinated and uncoordinated water molecules and uncoordinated imidazole Na toms play decisive roles for the high-performancep roton conductiona nd recognition ability for formic acid.B oth ZZU-1 and ZZU-2 showt emperature-and humidity-dependent proton-conducting characteristics with high conductivities of 8.95 10 À4 and 4.63 10 À4 Scm -1 at 98 %R Ha nd 100 8C, respectively.I mportantly,t he impedance values of the two MOF-based sensors decrease upon exposure to formica cid vapor generated from formic aqueous solutions at 25 8Cw ith good reproducibility.B yc omparing the changes of impedance values, we can indirectly determine the concentration of HCOOHi na queous solution.T he results showedt hat the lowest detectablec oncentrations of formic acid aqueous solutions are 1.2 10 À2 mol L À1 by ZZU-1 and 2.0 10 À2 mol L À1 by ZZU-2.F urthermore,t he two sensors can distinguish formic acid vapor from interfering vapors including MeOH, N-hexane, benzene, toluene, EtOH, acetone,a cetic acid and butane. Our research provides a new platform of proton-conductive MOFs-based sensors for detecting formic acid.[a] R.
Summary
The gastrointestinal (GI) tract represents the first barrier against the penetration of organisms by dietary advanced glycation end products (AGEs), but the tissue accumulation of AGEs and AGE‐induced effects on the GI tract have yet to be completely elucidated. This study aimed to investigate the tissue accumulation of AGEs and AGE‐induced oxidative stress and inflammation in the GI tract of rats after long‐term consumption of AGEs from bread crust (BC). The GI tract was then removed to analyse carboxymethyllysine (CML) and malondialdehyde (MDA) contents, the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH‐Px) and the levels of tumour necrosis factor‐α (TNF‐α) and interleukin‐6 (IL‐6). This study demonstrates that the oral intake of AGEs promotes their accumulation in the GI tract, and AGEs attenuate the first‐line antioxidant defence and stimulate the inflammatory response of the GI tract by downregulating enzymatic antioxidative pathways and increasing inflammatory cytokine levels.
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