Efficient bioconversion of raspberry ketone in Escherichia coli using fatty acids feedstocks.

BACKGROUND: Phenylpropanoid including raspberry ketone, is a kind of important natural plant product and widely used in pharmaceuticals, chemicals, cosmetics, and healthcare products. Bioproduction of phenylpropanoid in Escherichia coli and other microbial cell factories is an attractive approach considering the low phenylpropanoid contents in plants. However, it is usually difficult to produce high titer phenylpropanoid production when fermentation using glucose as carbon source. Developing novel bioprocess using alternative sources might provide a solution to this problem. In this study, typical phenylpropanoid raspberry ketone was used as the target product to develop a biosynthesis pathway for phenylpropanoid production from fatty acids, a promising alternative low-cost feedstock. RESULTS: A raspberry ketone biosynthesis module was developed and optimized by introducing 4-coumarate-CoA ligase (4CL), benzalacetone synthase (BAS), and raspberry ketone reductase (RZS) in Escherichia coli strains CR1-CR4. Then strain CR5 was developed by introducing raspberry ketone biosynthesis module into a fatty acids-utilization chassis FA09 to achieve production of raspberry ketone from fatty acids feedstock. However, the production of raspberry ketone was still limited by the low biomass and unable to substantiate whole-cell bioconversion process. Thus, a process by coordinately using fatty-acids and glycerol was developed. In addition, we systematically screened and optimized fatty acids-response promoters. The optimized promoter Pfrd3 was then successfully used for the efficient expression of key enzymes of raspberry ketone biosynthesis module during bioconversion from fatty acids. The final engineered strain CR8 could efficiently produce raspberry ketone repeatedly using bioconversion from fatty acids feedstock strategy, and was able to produce raspberry ketone to a concentration of 180.94 mg/L from soybean oil in a 1-L fermentation process. CONCLUSION: Metabolically engineered Escherichia coli strains were successfully developed for raspberry ketone production from fatty acids using several strategies, including optimization of bioconversion process and fine-tuning key enzyme expression. This study provides an essential reference to establish the low-cost biological manufacture of phenylpropanoids compounds.

Improved production of germacrene A, a direct precursor of ß-elemene, in engineered Saccharomyces cerevisiae by expressing a cyanobacterial germacrene A synthase.

BACKGROUND: The sesquiterpene germacrene A is a direct precursor of ß-elemene that is a major component of the Chinese medicinal herb Curcuma wenyujin with prominent antitumor activity. The microbial platform for germacrene A production was previously established in Saccharomyces cerevisiae using the germacrene A synthase (LTC2) of Lactuca sativa. RESULTS: We evaluated the performance of LTC2 (LsGAS) as well as nine other identified or putative germacrene A synthases from different sources for the production of germacrene A. AvGAS, a synthase of Anabaena variabilis, was found to be the most efficient in germacrene A production in yeast. AvGAS expression alone in S. cerevisiae CEN.PK2-1D already resulted in a substantial production of germacrene A while LTC2 expression did not. Further metabolic engineering the yeast using known strategies including overexpression of tHMGR1 and repression of squalene synthesis pathway led to an 11-fold increase in germacrene A production. Site-directed mutagenesis of AvGAS revealed that while changes of several residues located within the active site cavity severely compromised germacrene A production, substitution of Phe23 located on the lateral surface with tryptophan or valine led to a 35.2% and 21.8% increase in germacrene A production, respectively. Finally, the highest production titer of germacrene A reached 309.8 mg/L in shake-flask batch culture. CONCLUSIONS: Our study highlights the potential of applying bacterial sesquiterpene synthases with improved performance by mutagenesis engineering in producing germacrene A.

Biotransformation of dietary phytoestrogens by gut microbes: A review on bidirectional interaction between phytoestrogen metabolism and gut microbiota.

Phytoestrogens are a class of plant produced polyphenolic compounds with diphenolic structure, which is similar to 17ß-estradiol. These phytoestrogens preferentially bind to estrogen receptors, however, with weak affinity. Recently, many studies have found that these phytoestrogens can be transformed by gut microbiota through novel enzymatic reactions into metabolites with altered bioactivity. Recent studies have also implied that these metabolites could possibly modulate the host gut ecosystem, gene expression, metabolism and the immune system. Thus, isolating gut microbes capable of biotransforming phytoestrogens and characterizing the novel enzymatic reactions involved are principal to understand the mechanisms of beneficial effects brought by gut microbiota and their metabolism on phytoestrogens, and to provide the theoretical knowledge for the development of functional probiotics. In the present review, we summarized works on gut microbial biotransformation of phytoestrogens, including daidzin (isoflavone), phenylnaringenin (prenylflavonoid), lignans, resveratrol (stilbene) and ellagitannins. We mainly focus on gut bacterial isolation, metabolic pathway characterization, and the bidirectional interaction of phytoestrogens with gut microbes to illustrate the novel metabolic capability of gut microbiota and the methods used in these studies.

Efficient production of 3-hydroxypropionate from fatty acids feedstock in Escherichia coli.

The production of chemicals from renewable biomass resources is usually limited by factors including high-cost processes and low efficiency of biosynthetic pathways. Fatty acids (FAs) are an ideal alternative biomass. Their advantages include high-efficiently producing acetyl-CoA and reducing power, coupling chemical production with CO2 fixation, and the fact that they are readily obtained from inexpensive feedstocks. The important platform chemical 3-hydroxypropionate (3HP) can be produced from FAs as the feedstock with a theoretical yield of 2.49 g/g, much higher than the theoretical yield from other feedstocks. In this study, we first systematically analyzed the limiting factors in FA-utilization pathways in Escherichia coli. Then, we optimized FA utilization in Escherichia coli by using a combination of metabolic engineering and optimization of fermentation conditions. The 3HP biosynthesis module was introduced into a FA-utilizing strain, and the flux balance was finely optimized to maximize 3HP production. The resulting strain was able to produce 3HP from FAs with a yield of 1.56 g/g, and was able to produce 3HP to a concentration of 52 g/L from FAs in a 5-L fermentation process. The strain also could produce 3HP from various type of FAs feedstock including gutter oil. This is the first report of a technique for the efficient production of the platform chemical 3HP from FAs.

Treatment of Danhong Injection Combined with Naoxintong Capsule in Acute Coronary Syndrome Patients Undergoing PCI Operation: Study for a Randomized Controlled and Double-Blind Trial.

OBJECTIVE: This double-blind and randomized placebo-controlled trial evaluated the safety and efficacy of Danhong injection combined with Naoxintong capsule in patients with acute coronary syndrome (ACS) after percutaneous coronary intervention (PCI). METHODS: ACS patients scheduled to undergo PCI (n = 130) were equally and randomly apportioned to either a treatment or control group. After PCI, the treatment group received Danhong injection combined with Naoxintong capsule for 12 weeks, while the control group was given placebo. Both groups were otherwise treated with conventional secondary prevention of coronary artery disease. The groups were primarily evaluated for clinical efficacy and cardiovascular events. Evaluative indicators of safety included adverse events, platelet count, and liver, renal, and blood coagulation functions. RESULT: No cardiovascular events or adverse reactions were observed in either group. The treatment group demonstrated better signs of clinical efficacy, including left ventricular ejection fraction, higher nitric oxide levels, and lower levels of endothelin-1 (ET-1) and von Willebrand factor (VWF). CONCLUSION: ACS patients treated with Danhong injection combined with Naoxintong capsule after PCI demonstrated better improvement with regard to markers associated with atherosclerosis and adverse cardiovascular events, without apparent adverse effects. Thus, Danhong injection combined with Naoxintong capsule was safe and effective for treating ACS patients after PCI.

Sorafenib versus Transarterial chemoembolization for advanced-stage hepatocellular carcinoma: a cost-effectiveness analysis.

BACKGROUND: Sorafenib and transarterial chemoembolization (TACE) might both provide survival benefit for advanced hepatocellular carcinoma (HCC). Adopting either as a first-line therapy carries major cost and resource implications. We aimed to estimate the cost-effectiveness of sorafenib and TACE in advanced HCC. METHODS: A Markov model was constructed in a hypothetical cohort of patients aged 60 years with advanced HCC and Child-Pugh A/B cirrhosis over a 2-year time frame. Three strategies (full or dose-adjusted sorafenib and TACE) were compared in two cost settings: China and the USA. Transition probabilities, utility and costs were extracted from systematic review of 27 articles. Sensitivity analysis and Monte Carlo analysis were conducted. RESULTS: Full and dose-adjusted sorafenib respectively produced 0.435 and 0.482 quality-adjusted life years (QALYs) while TACE produced 0.375 QALYs. The incremental cost-effectiveness ratio (ICER) of full-dose sorafenib versus TACE was $101,028.83/QALY in China whereas full-dose sorafenib is a dominant strategy (ICER of -$1,014,507.20/ QALY) compared with TACE in the USA. Compared to full-dose sorafenib, dose-adjusted sorafenib was the dominant strategy with the negative ICERs in both China (-$132,238.94/QALY) and the USA (-$230,058.09/QALY). However, dose-adjusted sorafenib is not available currently, so full-dose sorafenib should be compared with TACE. As the acceptability curves shown, full-dose sorafenib was the optimal strategy at the accepted thresholds of WTP in these two countries. Specifically, full-dose sorafenib was the cost-effective treatment compared with TACE if a WTP was set above $21,670 in the USA, whereas in China, TACE could be more favorable than full-dose sorafenib if a WTP was set below $10,473. CONCLUSIONS: Dose-adjusted sorafenib may be cost-effective compared to full-dose sorafenib or TACE for advanced HCC patients. However, when confining the comparisons between full-dose sorafenib and TACE, full-dose sorafenib was cost-effective for these patients, under the accepted thresholds of WTP.

Exploring differences between left and right hand motor imagery via spatio-temporal EEG microstate.

EEG-based motor imagery is very useful in brain-computer interface. How to identify the imaging movement is still being researched. Electroencephalography (EEG) microstates reflect the spatial configuration of quasi-stable electrical potential topographies. Different microstates represent different brain functions. In this paper, microstate method was used to process the EEG-based motor imagery to obtain microstate. The single-trial EEG microstate sequences differences between two motor imagery tasks - imagination of left and right hand movement were investigated. The microstate parameters - duration, time coverage and occurrence per second as well as the transition probability of the microstate sequences were obtained with spatio-temporal microstate analysis. The results were shown significant differences (P < 0.05) with paired t-test between the two tasks. Then these microstate parameters were used as features and a linear support vector machine (SVM) was utilized to classify the two tasks with mean accuracy 89.17%, superior performance compared to the other methods. These indicate that the microstate can be a promising feature to improve the performance of the brain-computer interface classification.

Conservative treatment and percutaneous catheter drainage improve outcome of necrotizing pancreatitis.

BACKGROUND/AIMS: To investigate the clinical effects of the maximum conservative treatment algorithm with percutaneous catheter drainage (PCD) as the first choice for necrotizing pancreatitis (NP). METHODOLOGY: Retrospectively analyzed NP patients who had fine needle aspiration (FNA) for proven infection of necrosis which was considered an indication for surgery (n=22, group 1) compared to patients subjected to maximum conservative treatment with PCD in NP patients (n=30, group 2). RESULTS: On admission, most baseline data did not show any statistical difference between the two groups, In group 2, all patients were implemented maximum conservative treatment, 25 of 30 patients were cured by PCD (83.3%), open necrosectomy were needed for 3 patients (10.0%) and 2 dead during hospitalization (6.7%). Whereas, in group 1, surgical operation rate was 45.6% and hospital mortality 31.8%, both of the ratios differed significantly compared with group 2 (45.6% vs. 10%, P=0.004; 31.8% vs. 6.7%, P=0.046 respectively). Furthemore, Hospital stay were significantly higher in group 1 compared with group 2 (90±18.5 vs. 39±13.4; P=0.033). CONCLUSIONS: A conservative approach with PCD as the first choice to treatment NP might decrease the rate of surgical operation and mortality, and improve the outcome of NP.

Corn baked by burning coal triggered overexpression of osteopontin in hepatocytes of rats following fluorosis.

OBJECTIVE: To observe the expression of osteopontin (OPN) in hepatocytes of rats fed with corn baked by burning coal from fluorosis areas and a deficiency of calcium/protein intake following fluorosis. METHODS: A total of 48 Wistar rats as objects were randomly assorted into four groups: dose-free fluorine group, which were mainly fed with fluorine-free corn (56% structurally), dose-free fluorine with biased dietary group, which were fed with lower contents of protein (119.41 g/kg) and calcium (0.68 g/kg), high-dose fluorine group (fluorine contents: 104.2 mg/kg), and high-dose fluorine with biased dietary group. After 180 days of cultivation, the contents of fluorine in the bones of rats were tested for the assessment of construction of fluorosis animal model. And the expression of OPN in hepatocytes of rats in different groups was detected with immunohistochemistry and reverse transcription polymerase chain reaction. RESULTS: The present study validated the result that OPN was overexpressed in hepatocytes following fluorosis after oral intake of burning coal-baked corn. OPN was expressed most significantly in high fluorine with biased dietary group, and the high-fluorine group ranked the second most; and dose-free fluorine with biased dietary group ranked the third. The dose-free fluorine group expressed the least OPN. CONCLUSION: Overexpression of OPN in hepatocytes following fluorosis after excess fluorine intake was involved in liver damage process, which was enhanced by deficiency of calcium and protein intake. The results also demonstrated that the development of fluorosis in Guizhou province was correlated with local baking staple corn as a way of excess intake of fluorine and deficiency of calcium/protein intake.

Ligand- and protein-based modeling studies of the inhibitors of human cytochrome P450 2D6 and a virtual screening for potential inhibitors from the Chinese herbal medicine, Scutellaria baicalensis (Huangqin,Baikal Skullcap).

We have previously examined the binding patterns of various substrates to human cytochrome P450 2D6 (CYP2D6) using a series of molecular modeling methods. In this study, we further explored the binding modes of various types of inhibitors to CYP2D6 using a combination of ligand- and protein-based modeling approaches. Firstly, we developed and validated a pharmacophore model for CYP2D6 inhibitors, which consisted of two hydrophobic features and one hydrogen bond acceptor feature. Secondly, we constructed and validated a quantitative structure-activity relationship (QSAR) model for CYP2D6 inhibitors which gave a poor to moderate prediction accuracy. Thirdly, a panel of CYP2D6 inhibitors were subject to molecular docking into the active site of wild-type and mutated CYP2D6 enzyme. We demonstrated that 8 residues in the active site (Leu213, Glu216, Ser217, Gln244, Asp301, Ser304, Ala305, and Phe483) played an important role in the binding to the inhibitors via hydrogen bond formation and/or π-π stacking interaction. Apparent changes in the binding modes of the inhibitors have been observed with Phe120Ile, Glu216Asp, Asp301Glu mutations in CYP2D6. Finally, we screened for potential binders/inhibitors from the Chinese herbal medicine Scutellaria baicalensis (Huangqin, Baikal Skullcap) using the established pharmacophore model for CYP2D6 inhibitors and molecular docking approach. Overall, 18 out of 40 compounds from S. baicalensis were mapped to the pharmacophore model of CYP2D6 inhibitors and most herbal compounds from S. baicalensis could be docked into the active site of CYP2D6. Our study has provided insights into the molecular mechanisms of interaction of synthetic and herbal compounds with human CYP2D6 and further benchmarking studies are needed to validate our modeling and virtual screening results.

Pharmacophore, QSAR, and binding mode studies of substrates of human cytochrome P450 2D6 (CYP2D6) using molecular docking and virtual mutations and an application to chinese herbal medicine screening.

The highly polymorphic human cytochrome P450 2D6 (CYP2D6) metabolizes about 25% of currently used drugs. In this study, we have explored the interaction of a large number of substrates (n = 120) with wild-type and mutated CYP2D6 by molecular docking using the CDOCKER module. Before we conducted the molecular docking and virtual mutations, the pharmacophore and QSAR models of CYP2D6 substrates were developed and validated. Finally, we explored the interaction of a traditional Chinese herbal formula, Fangjifuling decoction, with CYP2D6 by virtual screening. The optimized pharmacophore model derived from 20 substrates of CYP2D6 contained two hydrophobic features and one hydrogen bond acceptor feature, giving a relevance ratio of 76% when a validation set of substrates were tested. However, our QSAR models gave poor prediction of the binding affinity of substrates. Our docking study demonstrated that 117 out of 120 substrates could be docked into the active site of CYP2D6. Forty one out of 117 substrates (35.04%) formed hydrogen bonds with various active site residues of CYP2D6 and 53 (45.30%) substrates formed a strong π-π interaction with Phe120 (53/54), with only carvedilol showing π-π interaction with Phe483. The active site residues involving hydrogen bond formation with substrates included Leu213, Lys214, Glu216, Ser217, Gln244, Asp301, Ser304, Ala305, Phe483, and Phe484. Furthermore, the CDOCKER algorithm was further applied to study the impact of mutations of 28 active site residues (mostly non-conserved) of CYP2D6 on substrate binding modes using five probe substrates including bufuralol, debrisoquine, dextromethorphan, sparteine, and tramadol. All mutations of the residues examined altered the hydrogen bond formation and/or aromatic interactions, depending on the probe used in molecular docking. Apparent changes of the binding modes have been observed with the Glu216Asp and Asp301Glu mutants. Overall, 60 compounds out of 130 from Fangjifuling decoction matched our pharmacophore model for CYP2D6 substrates. Fifty four out of these 60 compounds could be docked into the active site of CYP2D6 and 24 of 54 compounds formed hydrogen bonds with Glu216, Asp301, Ser304, and Ala305 in CYP2D6. These results have provided further insights into the factors that determining the binding modes of substrates to CYP2D6. Screening of high-affinity ligands for CYP2D6 from herbal formula using computational models is a useful approach to identify potential herb-drug interactions.

Inhibition effect of tetrandrine on haze formation after Epi-LASIK surgery in rabbits.

PURPOSE: To observe the inhibitory effect of tetrandrine on haze formation after Epi-LASIK surgery in rabbits. MATERIALS AND METHODS: Twenty-seven healthy New Zealand rabbits were selected and underwent Epi-LASIK surgery. According to a self comparison principle, these rabbits were randomly divided into three groups. The first group was treated with tetrandrine eye drops (Tet), the second (negative control, NC) group was treated with pure solvent, and the third group was treated with fluorometholone (FML) solvent. Haze grades of each group were respectively observed by slit lamp exam at half-month, one month, and two months after surgery. After corneal tissues were extracted, optical microscopy, Sirius Red staining, immunohistochemistry, and semi-quantitative RT-PCR tests were conducted, in order to test collagen formation of operated eyes after surgery and expression of transformation growth factor beta 2 (TGF-ß(2)) in corneal stroma. RESULTS: At a half month and one month after surgery, haze grades and type III collagen expression in Tet and FML groups were significantly lower than that in NC groups (P < 0.01). No statistical difference was observed between Tet and FML groups. Immunohistochemistry showed that, at each time point after surgery, expressions of TGF-ß(2) protein in Tet and FML groups were significantly lower than that in the NC group (P < 0.01), whereas there was no statistical difference between Tet and FML groups. The expression level of TGF-ß(2) protein increased, reaching its peak one month after surgery. RT-PCR also showed that, at each point after surgery, the TGF-ß(2) mRNA expression in Tet and FML groups was lower than that in the NC group (P < 0.01), nevertheless no statistical difference was observed between Tet and FML groups. CONCLUSIONS: Like FML, Tet could inhibit haze formation in rabbits after Epi-LASIK surgery, possible through TGF-ß(2)-collagen-III pathway.

[Clinical observation on treating diabetic macular edema with intravitreal triamcinolone acetonide and laser].

PURPOSE: To evaluate the effect of intravitreal injection of triamcinolone acetonide(IVTA) combining with retinal laser treating for diabetic macular edema(DME). METHODS: Twenty five patients(32 eyes) with DME who has microangioma in macula lutea were randomly divided into group A, B,C and D(8 eyes each group). Eyes in group A were treated with laser photocoagulation. Eyes in group B were treated with multiplier-532 laser photocoagulation and transpupillary thermotherapy. Eyes in group C were treated with multiplier-532 laser photocoagulation and intravitreal triamcinolone acetonide. Eyes in group D were treated with multiplier-532 laser, transpupillary thermotherapy plus triamcinolone acetonide injection. Intravitreal injection of 4 mg triamcinolone acetonide was done 1 week after laser photocoagulation in group C and D. The visual acuity, intraocular pressure, macular thickness (foveal thickness) of the eyes in 4 groups were observed before and 1, 3 and 6 months after treatment. RESULTS: The visual acuity, intraocular pressure and foveal thickness of the 4 groups before treatment showed no significant difference(p> ). The visual acuity, intraocular pressure, macular thickness of eyes in group A, B were better than those of group C, D at 1, 3 and 6 months after treatment, and they had significant difference(p<0.05), while they didn't show significant difference between group A and B, group C and D(p>0.05). CONCLUSIONS: The effect of laser photocoagulation and intravitreal triamcinolone acetonide, laser photocoagulation combining with transpupillary thermotherapy plus triamcinolone acetonide injectionvisual treating for DME was better than laser photocoagulation alone, laser photocoagulation combining with transpupillary thermotherapy.

[NF-kappaB tumorigenesis and drug developement].

NF-kappaB, a collective name of dimeric transcription factors, is composed of members of the Rel family proteins that recognize and bind a specific DNA sequence. It is normally sequestered in the cytoplasm of non-stimulated cells by associating with a family of inhibitor proteins called IkappaBs. Exposure of cells to a variety of extra-and intra-cellular stimuli leads to the rapid proteolytic degradation of IkappaBs, which frees NF-kappaBs allowing them to translocate to the nucleus where it regulates gene transcription. NF-kappaB is involved in a lot of physiological processes such as immunity, inflammation, cell proliferation, apoptosis and even tumorigenesis by regulating the transcription of a larger number of genes. This review introduces the various mechanisms of NF-kappaB activation including a recently reported alternative activation pathway mediated by lymphotoxin alpha/beta, B cell activating factor and CD40 ligand. The signal transduction pathway leading to NF-kappaB activation via IKK in response to proinflammatory factors like TNF-alpha and IL-1 is addressed in more detail concerning the regulation of IKK activity, mechanism of IkappaB degradation and regulation of transactivation activity of NF-kappaB on different levels. Considering the important role of NF-kappaB in cell proliferation and regulation of various genes participating in apoptosis, the involvement of NF-kappaB in tumorigenesis and drug screening is also discussed.