4 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:1380-1387.
BackgroundRiboflavin (vitamin B2), the precursor of the flavin cofactors flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), is used commercially as an animal feed supplement and food colorant. E. coli is a robust host for various genetic manipulations and has been employed for efficient production of biofuels, polymers, amino acids, and bulk chemicals. Thus, the aim of this study was to understand the metabolic capacity of E. coli for the riboflavin production by modification of central metabolism, riboflavin biosynthesis pathway and optimization of the fermentation conditions.ResultsThe basic producer RF01S, in which the riboflavin biosynthesis genes ribABDEC from E. coli were overexpressed under the control of the inducible trc promoter, could accumulate 229.1 mg/L of riboflavin. Further engineering was performed by examining the impact of expression of zwf (encodes glucose 6-phosphate dehydrogenase) and gnd (encodes 6-phosphogluconate dehydrogenase) from Corynebacterium glutamicum and pgl (encodes 6-phosphogluconolactonase) from E. coli on riboflavin production. Deleting pgi (encodes glucose-6-phosphate isomerase) and genes of Entner-Doudoroff (ED) pathway successfully redirected the carbon flux into the oxidative pentose phosphate pathway, and overexpressing the acs (encodes acetyl-CoA synthetase) reduced the acetate accumulation. These modifications increased riboflavin production to 585.2 mg/L. By further modulating the expression of ribF (encodes riboflavin kinase) for reducing the conversion of riboflavin to FMN in RF05S, the final engineering strain RF05S-M40 could produce 1036.1 mg/L riboflavin in LB medium at 37°C. After optimizing the fermentation conditions, strain RF05S-M40 produced 2702.8 mg/L riboflavin in the optimized semi-defined medium, which was a value nearly 12-fold higher than that of RF01S, with a yield of 137.5 mg riboflavin/g glucose.ConclusionsThe engineered strain RF05S-M40 has the highest yield among all reported riboflavin production strains in shake flask culture. This work collectively demonstrates that E. coli has a potential to be a microbial cell factory for riboflavin bioproduction.
BackgroundMucus hypersecretion contributes to the morbidity and mortality of smoking-related lung diseases, especially chronic obstructive pulmonary disease (COPD), which starts in the small airways. Despite progress in animal studies, the genes and their expression pattern involved in mucus production and secretion in human airway epithelium are not well understood. We hypothesized that comparison of the transcriptomes of the small airway epithelium of individuals that express high vs low levels of MUC5AC, the major macromolecular component of airway mucus, could be used as a probe to identify the genes related to human small airway mucus production/secretion.MethodsFlexible bronchoscopy and brushing were used to obtain small airway epithelium (10th to 12th order bronchi) from healthy nonsmokers (n=60) and healthy smokers (n=72). Affymetrix HG-U133 plus 2.0 microarrays were used to assess gene expression. Massive parallel sequencing (RNA-Seq) was used to verify gene expression of small airway epithelium from 5 nonsmokers and 6 smokers.ResultsMUC5AC expression varied 31-fold among the healthy nonsmokers. Genome-wide comparison between healthy nonsmokers (n = 60) grouped as “high MUC5AC expressors” vs “low MUC5AC expressors” identified 528 genes significantly up-regulated and 15 genes significantly down-regulated in the high vs low expressors. This strategy identified both mucus production and secretion related genes under control of a network composed of multiple transcription factors. Based on the literature, genes in the up-regulated list were used to identify a 73 “MUC5AC-associated core gene” list with 9 categories: mucus component; mucus-producing cell differentiation-related transcription factor; mucus-producing cell differentiation-related pathway or mediator; post-translational modification of mucin; vesicle transport; endoplasmic reticulum stress-related; secretory granule-associated; mucus secretion-related regulator and mucus hypersecretory-related ion channel. As a validation cohort, we assessed the MUC5AC-associated core gene list in the small airway epithelium of an independent set of healthy smokers (n = 72). There was up-regulation of MUC5AC in the small airway epithelium of smokers (2.3-fold, p < 10-8) associated with a coordinated up-regulation of MUC5AC-associated core gene expression pattern in the small airway epithelium of smokers (p < 0.01). Deep sequencing confirmed these observations.ConclusionThe identification of the genes associated with increased airway mucin production in humans should be useful in understanding the pathogenesis of airway mucus hypersecretion and identifying therapeutic targets.Author summaryMucus hypersecretion contributes to the morbidity and mortality of smoking-related lung diseases, especially chronic obstructive pulmonary disease (COPD), which starts in the small airways. Little is known about the gene networks associated with the synthesis and secretion of mucins in the human small airway epithelium. Taking advantage of the knowledge that MUC5AC is a major muc...
PurposeThis study aimed to investigate the regional spontaneous brain activity changes in primary dysmenorrhea (PD) patients in different phases of the menstrual cycle by regional homogeneity (ReHo) analysis.Patients and methodsThirty-three PD patients and 32 healthy controls (HCs) separately received resting-state functional magnetic resonance imaging during menstrual phase and follicular phase (non-menstrual phase). Cox retrospective symptom scale (RSS), Self-Rating Anxiety Scale (SAS) and Self-Rating Depression Scale (SDS) were applied to assess related symptoms and emotions.ResultsThere was no significant difference between the two groups in demographic data. The PD patients obtained higher RSS score, SAS score and SDS score than HCs. Compared with HCs, the ReHo values of the PD patients were increased in left midbrain and hippocampus, right posterior cingulate cortex (PCC), insula and middle temporal cortex (MTC) and decreased in left dorsolateral prefrontal cortex and right medial prefrontal cortex (mPFC) in menstrual phase. In non-menstrual phase, enhanced ReHo values were found in bilateral S1 and precuneus, left S2 and MTC, and reduced ReHo values were observed in left mPFC and orbital frontal cortex. RSS score positively correlated with ReHo values of midbrain and negatively correlated with mPFC and PCC.ConclusionOur results suggested that PD is accompanied by dynamic regional spontaneous activity changes across the menstrual cycle, and the altered regions were involved in descending pain modulation, default mode network and sensory modulation. These abnormal activations might contribute to maintain the menstrual pain.
Background: The present study aimed to investigate the use of imaging biomarkers to predict the outcome of acupuncture in patients with migraine without aura (MwoA). Methods: Forty-one patients with MwoA received 4 weeks of acupuncture treatment and two brain imaging sessions at the Beijing Traditional Chinese Medicine Hospital affiliated with Capital Medical University. Patients kept a headache diary for 4 weeks before treatment and during acupuncture treatment. Responders were defined as those with at least a 50% reduction in the number of migraine days. The machine learning method was used to distinguish responders from non-responders based on pre-treatment brain gray matter (GM) volume. Longitudinal changes in GM predictive regions were also analyzed. Results: After 4 weeks of acupuncture, 19 patients were classified as responders. Based on 10-fold cross-validation for the selection of GM features, the linear support vector machine produced a classification model with 73% sensitivity, 85% specificity, and 83% accuracy. The area under the receiver operating characteristic curve was 0.7871. This classification model included 10 GM areas that were mainly distributed in the frontal, temporal, parietal, precuneus, and cuneus gyri. The reduction in the number of migraine days was correlated with baseline GM volume in the cuneus, parietal, and frontal gyri in all patients. Moreover, the left cuneus showed a longitudinal increase in GM volume in responders. Conclusion: The results suggest that pre-treatment brain structure could be a novel predictor of the outcome of acupuncture in the treatment of MwoA. Imaging features could be a useful tool for the prediction of acupuncture efficacy, which would enable the development of a personalized medicine strategy.
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