152 research outputs found

    Low Pressure Ethenolysis of Renewable Methyl Oleate in a Microchemical System

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    A microchemical system for ethenolysis of renewable methyl oleate was developed, in which the dual-phase, microfluidic design enabled efficient diffusion of ethylene gas into liquid methyl oleate through an increased contact area. The increased mass transfer of ethylene favored the formation of desired commodity chemicals with significantly suppressed homometathesis when compared to the bulk system. In addition to higher selectivity and conversion, this system also provides the typical advantages of a microchemical system, including the possibility of convenient scale-up

    Flux analysis of the Lactobacillus reuteri propanediol-utilization pathway for production of 3-hydroxypropionaldehyde, 3-hydroxypropionic acid and 1,3-propanediol from glycerol

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    Background Lactobacillus reuteri converts glycerol to 3-hydroxypropionic acid (3HP) and 1,3-propanediol (1,3PDO) via 3-hydroxypropionaldehyde (3HPA) as an intermediate using enzymes encoded in its propanediol-utilization (pdu) operon. Since 3HP, 1,3PDO and 3HPA are important building blocks for the bio-based chemical industry, L. reuteri can be an attractive candidate for their production. However, little is known about the kinetics of glycerol utilization in the Pdu pathway in L. reuteri. In this study, the metabolic fluxes through the Pdu pathway were determined as a first step towards optimizing the production of 3HPA, and co-production of 3HP and 1,3PDO from glycerol. Resting cells of wild-type (DSM 20016) and recombinant (RPRB3007, with overexpressed pdu operon) strains were used as biocatalysts. Results The conversion rate of glycerol to 3HPA by the resting cells of L. reuteri was evaluated by in situ complexation of the aldehyde with carbohydrazide to avoid the aldehyde-mediated inactivation of glycerol dehydratase. Under operational conditions, the specific 3HPA production rate of the RPRB3007 strain was 1.9 times higher than that of the wild-type strain (1718.2 versus 889.0 mg/gCDW.h, respectively). Flux analysis of glycerol conversion to 1,3PDO and 3HP in the cells using multi-step variable-volume fed-batch operation showed that the maximum specific production rates of 3HP and 1,3PDO were 110.8 and 93.7 mg/gCDW.h, respectively, for the wild-type strain, and 179.2 and 151.4 mg/gCDW.h, respectively, for the RPRB3007 strain. The cumulative molar yield of the two compounds was ~1 mol/mol glycerol and their molar ratio was ~1 mol3HP/mol1,3PDO. A balance of redox equivalents between the glycerol oxidative and reductive pathway branches led to equimolar amounts of the two products. Conclusions Metabolic flux analysis was a useful approach for finding conditions for maximal conversion of glycerol to 3HPA, 3HP and 1,3PDO. Improved specific production rates were obtained with resting cells of the engineered RPRB3007 strain, highlighting the potential of metabolic engineering to render an industrially sound strain. This is the first report on the production of 3HP and 1,3PDO as sole products using the wild-type or mutant L. reuteri strains, and has laid ground for further work on improving the productivity of the biotransformation process using resting cells

    The relative abundance of APOE and Aβ1-42 associated with abnormal prion protein differs between Creutzfeldt-Jakob disease subtypes

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    Aggregated and protease-resistant mammalian prion protein (PrP<sup>Sc</sup>) is the primary protein component of infectious prions. Enriched PrP<sup>Sc</sup> preparations are often used to study the mechanisms that underly prion disease. However, most enrichment procedures are relatively nonspecific and tend to yield significant amounts of non-PrP<sup>Sc</sup> components including various proteins that could confound functional and structural studies. It is thus important to identify these proteins and assess their potential relevance to prion pathogenesis. Following proteinase K treatment and phosphotungstic acid precipitation of brain homogenate, we have used mass spectrometry to analyze the protein content of PrP<sup>Sc</sup> isolated from prion-infected mice, multiple cases of sporadic Creutzfeldt-Jakob disease (sCJD), and human growth hormone associated cases of iatrogenic CJD (iCJD). Creatine kinase was the primary protein contaminant in all PrP<sup>Sc</sup> samples, while many of the other proteins identified were also found in non-CJD controls, which suggests that they are not CJD specific. Interestingly, the Alzheimer’s disease associated peptide amyloid β 1–42 (Aβ1–42) was identified in the majority of the sCJD cases as well as non-CJD age-matched controls, while apoliprotein E was found in greater abundance in the sCJD cases. By contrast, while some of the iCJD cases showed evidence of higher molecular weight Aβ oligomers, monomeric Aβ1–42 peptide was not detected by immunoblot, and only one case had significant levels of apolipoprotein E. Our data are consistent with the age-associated deposition of Aβ1–42 in older sporadic CJD and non-CJD patients and suggest that both apolipoprotein E and Aβ1–42 abundance can differ depending upon the type of CJD

    Craniopharyngioma in the Temporal Lobe: A Case Report

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    Herein, we report on an unusual case of craniopharyngioma arising in the temporal lobe with no prior history of surgery and with no connection to the craniopharyngeal duct. MR images showed a cystic tumor with a small solid portion. To the best of our knowledge, this is the first case of a craniopharyngioma occurring in the temporal lobe

    Science Impacts of the SPHEREx All-Sky Optical to Near-Infrared Spectral Survey: Report of a Community Workshop Examining Extragalactic, Galactic, Stellar and Planetary Science

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    SPHEREx is a proposed SMEX mission selected for Phase A. SPHEREx will carry out the first all-sky spectral survey and provide for every 6.2" pixel a spectra between 0.75 and 4.18 μ\mum [with R∼\sim41.4] and 4.18 and 5.00 μ\mum [with R∼\sim135]. The SPHEREx team has proposed three specific science investigations to be carried out with this unique data set: cosmic inflation, interstellar and circumstellar ices, and the extra-galactic background light. It is readily apparent, however, that many other questions in astrophysics and planetary sciences could be addressed with the SPHEREx data. The SPHEREx team convened a community workshop in February 2016, with the intent of enlisting the aid of a larger group of scientists in defining these questions. This paper summarizes the rich and varied menu of investigations that was laid out. It includes studies of the composition of main belt and Trojan/Greek asteroids; mapping the zodiacal light with unprecedented spatial and spectral resolution; identifying and studying very low-metallicity stars; improving stellar parameters in order to better characterize transiting exoplanets; studying aliphatic and aromatic carbon-bearing molecules in the interstellar medium; mapping star formation rates in nearby galaxies; determining the redshift of clusters of galaxies; identifying high redshift quasars over the full sky; and providing a NIR spectrum for most eROSITA X-ray sources. All of these investigations, and others not listed here, can be carried out with the nominal all-sky spectra to be produced by SPHEREx. In addition, the workshop defined enhanced data products and user tools which would facilitate some of these scientific studies. Finally, the workshop noted the high degrees of synergy between SPHEREx and a number of other current or forthcoming programs, including JWST, WFIRST, Euclid, GAIA, K2/Kepler, TESS, eROSITA and LSST.Comment: Report of the First SPHEREx Community Workshop, http://spherex.caltech.edu/Workshop.html , 84 pages, 28 figure

    Minilaparotomically Assisted Vaginal Hysterectomy

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    Endoscopic hysterectomy is increasingly selected as a current trend to minimize invasion, tissue trauma and early recovery. However it has disadvantages of the difficulty to learn and needs expensive equipments. So we developed a new minimally invasive method of vaginal hysterectomy-minilaparotomically assisted vaginal hysterectomy (MAVH) in order to complement the current laparoscopic surgery. The principle of MAVH is based on suprapubic minilaparotomical incision and uterine elevator that allows access and maximal exposure of the pelvic anatomy and an easy approach to the surrounding anatomy enabling division of round ligaments, Fallopian tubes, tuboovarian ligaments, and dissection of bladder peritoneum. After then, the vaginal phase of MAVH is done by the traditional vaginal hysterectomy. We enrolled 75 consecutive cases and in 73 cases thereof MAVH was accomplished successfully. The technique of MAVH is simple and easy to learn and it involves a small incision causing less pain and complications. This practice does not require expensive equipments. MAVH is considered as a safe and effective alternative method for abdominal hysterectomy in most cases
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