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Devin John Van Elburg, Scott D Noble, Simone Hagey, Andrew L Goertzen
Optical coupling is an important factor in detector design as it improves optical photon transmission by mitigating internal reflections at light-sharing boundaries. In this work we compare optical coupling materials, namely double-sided acrylic polymer tapes and silicone optical grease (SiG), in the context of positron emission tomography (PET). Four double-sided tapes from 3M of varying thicknesses (0.229mm-1.016mm) and adhesive materials ('100MP', adhesive 100 'A100', 'VHB') were characterized with spectrophotometer measurements and photopeak amplitude and energy resolution measurements using lutetium-yttrium oxy-orthosilicate (LYSO) coupled to photomultiplier tubes (PMT) or silicon photomultipliers (SiPMs)...
January 16, 2018: Physics in Medicine and Biology
Miao Liu, Siqi Li, Yongzhen Xie, Shiru Jia, Ying Hou, Yang Zou, Cheng Zhong
Oxygen plays a key role during bacterial cellulose (BC) biosynthesis by Gluconacetobacter xylinus. In this study, the Vitreoscilla hemoglobin (VHb)-encoding gene vgb, which has been widely applied to improve cell survival during hypoxia, was heterologously expressed in G. xylinus via the pBla-VHb-122 plasmid. G. xylinus and G. xylinus-vgb+ were statically cultured under hypoxic (10 and 15% oxygen tension in the gaseous phase), atmospheric (21%), and oxygen-enriched conditions (40 and 80%) to investigate the effect of oxygen on cell growth and BC production...
February 2018: Applied Microbiology and Biotechnology
Pengfei Ouyang, Huan Wang, Ivan Hajnal, Qiong Wu, Yingying Guo, Guo-Qiang Chen
Technologies enabling high-cell-density growth are required for economical industrial production of most biotechnological products. However, the key factor limiting cell density in bioreactors is the availability of oxygen during the late phases of fermentation. Although the expression of bacterial Vitreoscilla hemoglobin (VHb) is useful for enhanced oxygen availability, bacterial cell membrane makes efficient hemoglobin-oxygen contact a challenge. On the other hand, periplasmic spaces of Gram-negative microorganisms offer an excellent compartment for the intermittent storage of hemoglobin-bound oxygen...
January 2018: Metabolic Engineering
Jie Lin, Xiamei Zhang, Bingran Song, Wei Xue, Xiaoyun Su, Xiuzhen Chen, Zhiyang Dong
Trichoderma reesei is well known as an industrial workhorse fungus in cellulase production. The low dissolved oxygen supply in the highly viscous medium of T. reesei remains a major bottleneck that hampers growth and cellulase production in submerged fermentation. Vitreoscilla hemoglobin (VHb) has been demonstrated to improve metabolism and protein production in different heterologous hosts under hypoxic conditions, but the use of VHb in T. reesei remains uninvestigated. This study examines the effect of VHb in improving T...
November 15, 2017: AMB Express
Marcelo Siqueira de Oliveira, Romeu Paulo Martins Silva, Suiane da Costa Negreiros do Valle, Elisabeth Níglio de Figueiredo, Dayana Fram
Objective: compare chronic hepatitis B patients to those superinfected with hepatitis D virus, according to Child-Pugh score regarding disease severity. Method: retrospective descriptive study, performed with 59 patients followed in the ambulatory, of which 22 (37.3%) were chronically infected with hepatitis B virus (Group HBV) and 37 (62.7%) superinfected with Delta virus (Group HBV+HDV); variables of sex, age and items of Child-Pugh score were collected by consulting medical records...
September 2017: Revista Brasileira de Enfermagem
Huidan Zhang, Yingang Feng, Qiu Cui, Xiaojin Song
BACKGROUND: Arachidonic acid (ARA, C20:4, n-6), which belongs to the omega-6 series of polyunsaturated fatty acids and has a variety of biological activities, is commercially produced in Mortierella alpina. Dissolved oxygen or oxygen utilization efficiency is a critical factor for Mortierella alpina growth and arachidonic acid production in large-scale fermentation. Overexpression of the Vitreoscilla hemoglobin gene is thought to significantly increase the oxygen utilization efficiency of the cells...
August 30, 2017: BMC Biotechnology
Charlotte Lupton, Mohini Sengupta, Ruey-Kuang Cheng, Joanne Chia, Vatsala Thirumalai, Suresh Jesuthasan
Learning how to actively avoid a predictable threat involves two steps: recognizing the cue that predicts upcoming punishment and learning a behavioral response that will lead to avoidance. In zebrafish, ventral habenula (vHb) neurons have been proposed to participate in both steps by encoding the expected aversiveness of a stimulus. vHb neurons increase their firing rate as expectation of punishment grows but reduce their activity as avoidance learning occurs. This leads to changes in the activity of raphe neurons, which are downstream of the vHb, during learning...
May 2017: ENeuro
Eliana Castillo, Kellie Murphy, Julie van Schalkwyk
OBJECTIF: Examiner l'épidémiologie, l'histoire naturelle, l'évaluation et le traitement de l'infection au virus de l'hépatite B (VHB) durant la grossesse. Cela aidera les fournisseurs de soins obstétricaux à conseiller leurs patientes quant aux risques périnataux et aux options de prise en charge offertes aux femmes enceintes atteintes de l'hépatite B. ISSUES: Les éléments évalués comprennent les seuils de traitement antiviral contre le VHB pour la prévention de la transmission périnatale et pour les interventions effractives durant la grossesse pour les femmes atteintes de l'hépatite B...
March 2017: Journal of Obstetrics and Gynaecology Canada: JOGC, Journal D'obstétrique et Gynécologie du Canada: JOGC
Guoling Yin, Yu Yang, Feilong Song, Christophe Renard, Zhi-Min Dang, Chang-Yong Shi, Dongrui Wang
Dielectric elastomer generators (DEGs), which follow the physics of variable capacitors and harvest electric energy from mechanical work, have attracted intensive attention over the past decade. The lack of ideal dielectric elastomers, after nearly two decades of research, has become the bottleneck for DEGs' practical applications. Here, we fabricated a series of polyurethane-based ternary composites and estimated their potential as DEGs to harvest electric energy for the first time. Thermoplastic polyurethane (PU) with high relative permittivity (∼8) was chosen as the elastic matrix...
February 6, 2017: ACS Applied Materials & Interfaces
Tingzhen Mu, Maohua Yang, Jixiang Zhao, Moustafa Mohammed Sharshar, Jiangnan Tian, Jianmin Xing
OBJECTIVE: To construct efficient transformation and expression system and further improve desulfurizing activity of cells through expression of Vitreoscilla hemoglobin (VHb) in haloalkaliphilic Thialkalivibrio versutus SOB306. RESULTS: We transferred plasmids pKT230 and pBBR-sm(r) into T. versutus SOB306 via a conjugation method. We identified four promoters from among several predicted promoters by scoring for streptomycin resistance, and finally selected tac and p3 based on the efficiency of expression of red fluorescent protein (RFP)...
March 2017: Biotechnology Letters
Mariana Juárez, Claudia H González-De la Rosa, Elisa Memún, Juan-Carlos Sigala, Alvaro R Lara
Inefficient carbon metabolism is a relevant issue during the culture of mammalian cells for the production of biopharmaceuticals. Therefore, cell engineering strategies to improve the metabolic and growth performance of cell lines are needed. The expression of Vitreoscilla stercoraria hemoglobin (VHb) has been shown to significantly reduce overflow metabolism and improve the aerobic growth of bacteria. However, the effects of VHb on mammalian cells have been rarely studied. Here, the impact of VHb on growth and lactate accumulation during CHO-K1 cell culture was investigated...
March 2017: Biotechnology Journal
Xiaoliu Liu, Ping Zhu, Ruifan Jiang, Lingtian Wu, Xiaohai Feng, Sha Li, Hong Xu
Welan gum is a microbial polysaccharide produced by Sphingomonas sp. Its production is limited by the dissolved oxygen levels in the highly viscous fermentation. A strategy of heterologous expression of the Vitreoscilla hemoglobin gene in Sphingomonas sp. HT-1 was investigated to alleviate oxygen limitation and improve the yield of welan gum. Ultimately, the welan gum production increased from 25.3g/L to 34.6g/L, whereas the rheological behavior of welan gum solutions remained virtually unchanged. The transcriptional levels of the key genes in the electron transfer chain, TCA cycle and welan gum synthesis pathway, as well as ATP level revealed that the VHb expression in Sphingomonas sp...
January 20, 2017: Carbohydrate Polymers
Nigel E Bush, Derek J Smolenski, Lauren M Denneson, Holly B Williams, Elissa K Thomas, Steven K Dobscha
OBJECTIVE: The purpose of this study was to assess the impact of the Virtual Hope Box (VHB), a smartphone app to improve stress coping skills, suicidal ideation, and perceived reasons for living among patients at elevated risk of suicide and self-harm. METHODS: The authors conducted a parallel-group randomized controlled trial with two groups of U.S. service veterans in active mental health treatment who had recently expressed suicidal ideation. Between March 2014 and April 2015, 118 patients were enrolled in the study...
April 1, 2017: Psychiatric Services: a Journal of the American Psychiatric Association
Milan Shrestha, Gih-Keong Lau
This Letter presents a tunable window device based on microscopic wrinkling of a transparent elastomeric surface. "Crack-free" microscopic wrinkling of a 50-nm ZnO thin film is possible on a highly adhesive acrylic elastomer membrane (VHB 4910) upon partial release from a large radial pre-stretch of membrane. This ZnO-based tunable window device demonstrates reversible tunability between transparent and translucent states. At zero compression with a flat surface, the device is transparent with a 93% in-line transmittance at 550-nm wavelength...
October 1, 2016: Optics Letters
Alvaro R Lara, Karim E Jaén, Juan-Carlos Sigala, Martina Mühlmann, Lars Regestein, Jochen Büchs
Oxygen limitation can be used as a simple environmental inducer for the expression of target genes. However, there is scarce information on the characteristics of microaerobic promoters potentially useful for cell engineering and synthetic biology applications. Here, we characterized the Vitreoscilla hemoglobin promoter (Pvgb ) and a set of microaerobic endogenous promoters in Escherichia coli. Oxygen-limited cultures at different maximum oxygen transfer rates were carried out. The FMN-binding fluorescent protein (FbFP), which is a nonoxygen dependent marker protein, was used as a reporter...
February 17, 2017: ACS Synthetic Biology
Xiangchao Feng, Zhuo Ma, Jonathan V MacArthur, Christopher J Giuffre, Ashraf F Bastawros, Wei Hong
Inspired by the toughening mechanism of double-network (DN) hydrogels, a soft composite consisting of a fabric mesh and VHB tape layers was fabricated. The composite was as stiff as the fabric mesh, and as stretchable as the VHB tape. At certain compositions, the composite was significantly stronger and tougher than the base materials. The extensibility and toughness of the composite can be attributed to a damage delocalization mechanism similar to that of the DN gels. In the partially damaged regions, the fabric mesh fragmented into small islands, surrounded by the highly stretched VHB tapes...
October 3, 2016: Soft Matter
Zewang Guo, Xihua Zhao, Yuanzhi He, Tianxing Yang, Huifang Gao, Ganxi Li, Feixue Chen, Meijing Sun, Jung-Kul Lee, Liaoyuan Zhang
Acetoin (AC) is a volatile platform compound with various potential industrial applications. AC contains two stereoisomeric forms: (3S)-AC and (3R)-AC. Optically pure AC is important potential intermediate and widely used as a precursor to synthesize novel optically materials. In this study, chiral (3R)-AC production from meso-2,3-butanediol (meso-2,3-BD) was obtained using recombinant Escherichia coli cells co-expressing meso-2,3-butanediol dehydrogenase (meso-2,3-BDH), NADH oxidase (NOX) and hemoglobin protein (VHB) from Serratia sp...
October 6, 2016: Journal of Microbiology and Biotechnology
Taner Sar, Benjamin C Stark, Meltem Yesilcimen Akbas
Ethanol production from whey powder was investigated by using free as well as alginate immobilized E. coli and E. coli expressing Vitreoscilla hemoglobin (VHb) in both shake flask and fermenter cultures. Media with varying levels of whey (lactose contents of 3%, 5%, 8% or 15%) and yeast extract (0.3% or 0.5%) were evaluated with fermentation times of 48-96 h. Immobilization and VHb expression resulted in higher ethanol production with all media; the increases ranged from 2% to 89% for immobilization and from 2% to 182% for VHb expression...
March 4, 2017: Bioengineered
Tong-Xin Zhao, Mei Li, Xiang Zheng, Cheng-Hua Wang, Hong-Xin Zhao, Chong Zhang, Xin-Hui Xing
trans-4-Hydroxy-l-proline (Hyp) is a chiral amino acid conventionally produced by acid hydrolysis of animal collagen, a process which involves the bottleneck problems of low efficiency and heavy environmental pollution. Biotransformation of l-proline into Hyp using recombinant whole-cell biocatalysis with proline-4-hydroxylase (P4H) is an environmentally-friendly alternative method. Since biohydroxylation of proline by whole cells is a high-oxygen-demand process, oxygen transfer needs to be improved. To solve this problem, the Vitreoscilla hemoglobin gene (vgb) was integrated into the chromosome of recombinant Escherichia coli expressing the P4H gene originally from Dactylosporangium sp...
January 2017: Journal of Bioscience and Bioengineering
Di Liu, Ni Wan, Fuzhong Zhang, Yinjie J Tang, Stephen G Wu
Our recent (13) C-metabolic flux analysis ((13) C-MFA) study indicates that energy metabolism becomes a rate-limiting factor for fatty acid overproduction in E. coli strains (after "Push-Pull-Block" based genetic modifications). To resolve this bottleneck, Vitreoscilla hemoglobin (VHb, a membrane protein facilitating O2 transport) was introduced into a fatty-acid-producing strain to promote oxygen supply and energy metabolism. The resulting strain, FAV50, achieved 70% percent higher fatty acid titer than the parent strain in micro-aerobic shake tube cultures...
February 2017: Biotechnology and Bioengineering
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