Insula-specific responses induced by dental pain: a proton magnetic resonance spectroscopy study

OBJECTIVES: To evaluate whether induced dental pain leads to quantitative changes in brain metabolites within the left insular cortex after stimulation of the right maxillary canine and to examine whether these metabolic changes and the subjective pain intensity perception correlate. METHODS: Ten male volunteers were included in the pain group and compared with a control group of 10 other healthy volunteers. The pain group received a total of 87-92 electrically induced pain stimuli over 15 min to the right maxillary canine tooth. Contemporaneously, they evaluated the subjective pain intensity of every stimulus using an analogue scale. Neurotransmitter changes within the left insular cortex were evaluated by MR spectroscopy. RESULTS: Significant metabolic changes in glutamine (+55.1%), glutamine/glutamate (+16.4%) and myo-inositol (-9.7%) were documented during pain stimulation. Furthermore, there was a significant negative correlation between the subjective pain intensity perception and the metabolic levels of Glx, Gln, glutamate and N-acetyl aspartate. CONCLUSION: The insular cortex is a metabolically active region in the processing of acute dental pain. Induced dental pain leads to quantitative changes in brain metabolites within the left insular cortex resulting in significant alterations in metabolites. Negative correlation between subjective pain intensity rating and specific metabolites could be observed

Novel Phosphoinositides in Barley Aleurone Cells (Additional Evidence for the Presence of Phosphatidyl-scyllo-Inositol).

A novel isomer of phosphatidylinositol that differs in the structure of the head group was detected in barley (Hordeum vulgare cv Himalaya) seeds. In this paper we describe our efforts to elucidate the structure of the novel isomer. Evidence from a variety of techniques, including chemical modification of in vivo 32Pi- and myo-[3H]inositol-labeled compounds, gas chromatography-mass spectrometry analysis, in vivo incorporation of scyllo-[3H]inositol, and enzymatic studies that suggest that the structure is phosphatidylscyllo-inositol (scyllo-PI), is presented. The use of microwave energy to significantly enhance the slow rate of hydrolysis of phosphoinositides is described. The presence of scyllo-PI can be easily overlooked by the methods commonly employed; therefore, experimental considerations important for the detection of scyllo-PI are discussed

Influence of UGT2B10 Genotype on Urinary Excretion of 4‑(Methylnitrosamino)-1-(3-pyridyl)-1-butanol-<i>N-</i>glucuronide by African American Smokers

At similar smoking levels, African American’s lung cancer risk is as much as twice that of whites. We hypothesized that racial/ethnic differences in UDP-glucuronosyltransferase (UGT)-catalyzed glucuronidation of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), a detoxication pathway for the tobacco-specific lung carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) may contribute to this variable risk. UGT2B10 catalyzes NNAL-<i>N</i>-glucuronidation, and a UGT2B10 splice variant is common among African Americans. Smokers from two independent studies were genotyped for this variant (rs116294140) and an Asp67Tyr variant (rs61750900), and urinary NNAL and NNAL-glucuronide concentrations were quantified. In the first, no significant differences in NNAL-<i>N</i>-glucuronidation between African Americans (<i>n</i> = 257) and whites (<i>n</i> = 354) or between homozygous carriers of UGT2B10 variants (genetic score 2) and noncarriers (score 0) were detected. However, total NNAL glucuronidation by score 2 compared to score 0 smokers was lower (68.9 vs 71.2%, <i>p</i> < 0.0001). For NNAL-<i>N</i>-glucuronide to be more precisely quantified in a second study, a sensitive high-resolution LC-MS/MS-based method, which separated NNAL, NNAL-<i>O</i>-glucuronide, and NNAL-<i>N</i>-glucuronide prior to analysis, was developed. In this study, the excretion of total NNAL (free plus glucuronides) by African American (<i>n</i> = 52) and white (<i>n</i> = 54) smokers was not different; however, total NNAL glucuronidation by African Americans (64.0%) was slightly less than by whites (68.3%, <i>p</i> = 0.05). The mean NNAL-<i>N</i>-glucuronidation by African Americans was much lower than for whites (14 vs 24.9%, <i>p</i> < 0.00001), but the NNAL-<i>O</i>-glucuronidation was greater (50.0 vs 43.3%, <i>p</i> = 0.013). <i>UGT2B10</i> genotype influenced NNAL-<i>N</i>-glucuronidation; the geometric mean percentage <i>N</i>-glucuronidation was 22.5% for smokers with genetic score 0 (<i>n</i> = 57) and 11.2% for score 2 (<i>n</i> = 11). In summary, the high prevalence of a <i>UGT2B10</i> splice variant among African Americans results in lower NNAL-<i>N</i>-glucuronidation but only a small decrease in total NNAL glucuronidation. Therefore, despite the significant contribution of UGT2B10 to NNAL-<i>N-</i>glucuronidation, the <i>UGT2B10</i> genotype does not play a large role in NNAL detoxication. Any decrease in <i>N</i>-glucuronidation was accompanied by a parallel increase in <i>O</i>-glucuronidation

Ubiquinone accumulation improves osmotic-stress tolerance in Escherichia coli

Bacteria are thought to cope with fluctuating environmental solute concentrations primarily by adjusting the osmolality of their cytoplasm. To obtain insights into underlying metabolic adaptions, we analyzed the global metabolic response of Escherichia coli to sustained hyperosmotic stress using non-targeted mass spectrometry. We observed that 52% of 1,071 detected metabolites, including known osmoprotectants, changed abundance with increasing salt challenge. Unexpectedly, unsupervised data analysis revealed a substantial increase of most intermediates in the ubiquinone-8 (Q8) biosynthesis pathway and a 110-fold accumulation of Q8 itself, as confirmed by quantitative lipidomics. We then demonstrate that Q8 is necessary for acute and sustained osmotic stress tolerance using Q8 mutants and tolerance rescue through feeding non-respiratory Q8 analogues. Finally, in vitro experiments with artificial liposomes reveal mechanical membrane stabilization as a principal mechanism of Q8-mediated osmoprotection. Thus, we find that besides regulating intracellular osmolality, E. coli enhances its cytoplasmic membrane stability to withstand osmotic stress