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Biotechnology and Bioengineering

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https://www.readbyqxmd.com/read/30229866/drug-delivering-nerve-conduit-improves-regeneration-in-a-critical-sized-gap
#1
Pratima Labroo, David Hilgart, Brett Davis, Christopher Lambert, Himanshu Sant, Bruce Gale, Jill E Shea, Jayant Agarwal
Autologous nerve grafts are the current "gold standard" for repairing large nerve gaps. However, they cause morbidity at the donor nerve site and only a limited amount of nerve can be harvested. Nerve conduits are a promising alternative to autografts and can act as guidance cues for the regenerating axons, without the need to harvest donor nerve. Separately, it has been shown that localized delivery of GDNF can enhance axon growth and motor recovery. FK506, an FDA approved small molecule, has also been shown to enhance peripheral nerve regeneration...
September 19, 2018: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/30229865/synthetic-repetitive-extragenic-palindromic-rep-sequence-as-an-efficient-mrna-stabilizer-for-protein-production-and-metabolic-engineering-in-prokaryotic-cells
#2
Chen Deng, Xueqin Lv, Jianghua Li, Yanfeng Liu, Guocheng Du, Rodrigo Ledesma Amaro, Long Liu
In prokaryotic cells, 3'-5' exonucleases can attenuate mRNA directionally from the direction of the 3'-5' UTR, and thus improving the stability of mRNAs without influencing normal cell growth and metabolism is a key challenge for protein production and metabolic engineering. Herein, we significantly improved mRNA stability by using synthetic repetitive extragenic palindromic (REP) sequences as an effective mRNA stabilizer in two typical prokaryotic microbes, namely, Escherichia coli for the production of cyclodextrin glucosyltransferase (CGTase) and Corynebacterium glutamicum for the production of N-acetylglucosamine (GlcNAc)...
September 19, 2018: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/30229864/combinatorial-lentiviral-gene-delivery-of-pro-oligodendrogenic-factors-to-improve-myelination-of-regenerating-axons-after-spinal-cord-injury
#3
Dominique R Smith, Daniel J Margul, Courtney M Dumont, Mitchell A Carlson, Mary K Munsell, Mitchell Johnson, Brian J Cummings, Aileen J Anderson, Lonnie D Shea
Spinal cord injury (SCI) results in paralysis below the injury and strategies are being developed that support axonal regrowth, yet recovery lags, in part, because many axons are not re-myelinated. Herein, we investigated strategies to increase myelination of regenerating axons by over-expression of platelet-derived growth factor-AA (PDGF) and noggin either alone or in combination in a mouse SCI model. Noggin and platelet-derived growth factor aa (PDGF) have been identified as factors that enhance recruitment and differentiation of endogenous progenitors to promote myelination...
September 19, 2018: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/30229860/high-throughput-identification-of-factors-promoting-neuronal-differentiation-of-human-neural-progenitor-cells-in-microscale-3d-cell-culture
#4
Gregory J Nierode, Sneha Gopal, Paul Kwon, Douglas S Clark, David V Schaffer, Jonathan S Dordick
Identification of conditions for guided and specific differentiation of human stem and progenitor cells is important for continued development and engineering of in vitro cell culture systems for use in regenerative medicine, drug discovery and human toxicology. Three-dimensional (3D) and organotypic cell culture models have been used increasingly for in vitro cell culture because they may better model endogenous tissue environments. However, detailed studies of stem cell differentiation within 3D cultures remain limited, particularly with respect to high-throughput screening...
September 19, 2018: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/30199104/a-new-srna-mediated-post-transcriptional-regulation-system-for-bacillus-subtilis
#5
Sen Yang, Yang Wang, Chaobao Wei, Qingtao Liu, Xuerong Jin, Guocheng Du, Jian Chen, Zhen Kang
Many genetic tools for gene regulation have been developed during the past decades. Some of them edit genomic DNA, such as nucleotides deletions and insertions, while the others interfere with the gene transcriptions or mRNA translation. Here, we report a post-transcriptional regulation tool which is termed "Modulation via the sRNA-dependent operation system: MS-DOS" by engineering the type I toxin-antitoxin system in Bacillus subtilis. MS-DOS depends simply on insertion of an operation region (OPR, partial toxin encoding region) downstream of genomic open reading frame of interest and overexpression of the coupling antitoxin small RNA from a plasmid...
September 10, 2018: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/30199099/reverse-transduction-can-improve-efficiency-of-aav-vectors-in-transduction-resistant-cells
#6
Esther J Lee, Tawana M Robinson, Jeffrey J Tabor, Antonios G Mikos, Junghae Suh
Reverse transduction, also known as substrate-mediated gene delivery, is a strategy in which viral vectors are first coated onto a surface that subsequently comes into contact with mammalian cells. The cells internalize the surface-attached vectors, resulting in transgene expression. We hypothesized that forcing the interaction between cells and adeno-associated virus (AAV) vectors through a reverse transduction format would increase in vitro gene delivery efficiencies of the vectors in transduction-resistant cells...
September 10, 2018: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/30199096/a-fully-online-sensor-equipped-disposable-multiphase-microbioreactor-as-a-screening-platform-for-biotechnological-applications
#7
Susanna Lladó Maldonado, Peter Panjan, Shiwen Sun, Detlev Rasch, Adama Sesay, Torsten Mayr, Rainer Krull
A new disposable, multiphase, microbioreactor (MBR) (with a working volume of 550 μL) equipped with online sensors is presented for biotechnological screening research purposes owing to its high-throughput potential. Its design and fabrication, online sensor integration, and operation are described. During aerobic cultivation, sufficient oxygen supply is the most important factor that influences growth and product formation. The MBR is a microbubble column bioreactor (μBC), and the oxygen supply was realized by active pneumatic bubble aeration, ensuring sufficient volumetric liquid-phase mass transfer (k L a) and proper homogenization of the cultivation broth...
September 10, 2018: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/30199094/unraveling-the-genetic-basis-of-fast-l-arabinose-consumption-on-top-of-recombinant-xylose-fermenting-saccharomyces-cerevisiae
#8
Xin Wang, Junjie Yang, Sheng Yang, Yu Jiang
One major challenge in the bioconversion of lignocelluloses into ethanol is to develop Saccharomyces cerevisiae strains that can utilize all available sugars in biomass hydrolysates, especially the D-xylose and L-arabinose that cannot be fermented by the S. cerevisiae strain naturally. Here, we integrated an L-Arabinose Utilization Cassette (AUC) into the genome of an efficient D-xylose fermenting industrial diploid S. cerevisiae strain CIBTS0735 to make strain CIBTS1972. After evolving on arabinose, CIBTS1974 with excellent fermentation capacity was obtained...
September 10, 2018: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/30199091/fed-batch-production-of-l-tryptophan-from-glycerol-using-recombinant-escherichia-coli
#9
Julia Tröndle, Natalia Trachtmann, Georg A Sprenger, Dirk Weuster-Botz
L-tryptophan is an essential amino acid of high industrial interest that is routinely produced by microbial processes from glucose as carbon source. Glycerol is an alternative substrate providing a variety of economic and metabolic advantages. Process performance of the recombinant L-tryptophan producer E. coli NT367 was studied in controlled fed-batch processes. The chromosome of the recombinant L-tryptophan producer was equipped with additional genes coding for enzymes of the aromatic amino acids biosynthetic pathway and L-serine biosynthesis, including genes for feedback-resistant enzyme variants (trpE fbr , aroFBL and serA fbr ), deletions of enzymatic steps for the degradation of precursors or the product L-tryptophan (sdaB and tnaA), and alterations in the regulation of L-tryptophan metabolism (deletion of trpL and trpR)...
September 10, 2018: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/30199090/a-synthetic-enzymatic-pathway-for-extremely-thermophilic-acetone-production-based-on-the-unexpectedly-thermostable-acetoacetate-decarboxylase-from-clostridium-acetobutylicum
#10
Benjamin M Zeldes, Christopher T Straub, Jonathan K Otten, Michael W W Adams, Robert M Kelly
One potential advantage of an extremely thermophilic metabolic engineering host (Topt ≥ 70°C) is facilitated recovery of volatile chemicals from the vapor phase of an active fermenting culture. This process would reduce purification costs and concomitantly alleviate toxicity to the cells by continuously removing solvent fermentation products such as acetone or ethanol, a process we are calling "bio-reactive distillation." While extremely thermophilic heterologous metabolic pathways can be inspired by existing mesophilic versions, they require thermostable homologs of the constituent enzymes if they are to be utilized in extremely thermophilic bacteria or archaea...
September 10, 2018: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/30199089/dynamic-mass-spectrometry-probe-dmsp-for-esi-ms-monitoring-of-bioreactors-for-therapeutic-cell-manufacturing
#11
Mason A Chilmonczyk, Peter A Kottke, Hazel Y Stevens, Robert E Guldberg, Andrei G Fedorov
Large scale manufacturing of therapeutic cells requires bioreactor technologies with online feedback control enabled by monitoring of secreted biomolecular critical quality attributes (CQAs). Electrospray ionization mass spectrometry (ESI-MS) is a highly sensitive label-free method to detect and identify biomolecules, but requires extensive sample preparation prior to analysis, making online application of ESI-MS challenging. We present a microfabricated, monolithically integrated device capable of continuous sample collection, treatment, and direct infusion for ESI-MS detection of biomolecules in high salt solutions...
September 10, 2018: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/30171773/model-based-identification-of-cell-cycle-dependent-metabolism-and-putative-autocrine-effects-in-antibody-producing-cho-cell-culture
#12
Johannes Möller, Katrin Korte, Ralf Pörtner, An-Ping Zeng, Uwe Jandt
The understanding of cell-cycle dependent population heterogeneities in mammalian cell culture and their influence on production rates is still limited. Furthermore, metabolic regulations arising from self-expressed signal factors (autocrine/autoinhibitory factors) have been postulated in the past, but no determination of such effects have been made so far for fast-growing production CHO cells in chemically defined media. In this work, a novel approach combining near-physiological treatment of cells (including synchronization), population resolved mechanistic modeling and statistical analysis was developed to identify population inhomogeneities...
September 1, 2018: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/30171703/paracrine-potential-of-adipose-stromal-vascular-fraction-cells-to-recover-hypoxia-induced-loss-of-cardiomyocyte-function
#13
Myroslava Mytsyk, Giuseppe Isu, Giulia Cerino, Martin T R Grapow, Friedrich S Eckstein, Anna Marsano
Cell-based therapies shows promising results in cardiac function recovery mostly through paracrine-mediated processes (as angiogenesis) in chronic ischemia. In this study, we aim to develop a 2D (two-dimensional) in vitro cardiac hypoxia-model mimicking severe cardiac ischemia to specifically investigate the pro-survival paracrine effects of adipose tissue-derived stromal vascular fraction (SVF) cell secretome released upon three-dimensional (3D) culture. For the 2D-cardiac hypoxia-model, neonatal rat cardiomyocytes were cultured for 5 days at <1% (approaching anoxia) oxygen (O2 ) tension...
September 1, 2018: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/30171695/escherichia-coli-inner-membrane-display-system-for-high-throughput-screening-of-dimeric-proteins
#14
Migyeong Jo, Bora Hwang, Hyun Woung Yoon, Sang Taek Jung
Multimer formation is indispensable to the intrinsic biological functions of many natural proteins. For example, the human IgG antibody has two variable regions [heavy chain variable domain (VH) and light chain variable domain (VL)] that must be assembled for specific antigen binding, and homodimerization of the antibody's Fc domain is essential for eliciting therapeutic effector functions. For more efficient high-throughput directed evolution of multimeric proteins with ease of cultivation and handling, here we report a membrane protein drift and assembly (MPDA) system, in which a multimeric protein is displayed on a bacterial inner membrane by drifting and auto-assembling membrane-anchored subunit polypeptides...
September 1, 2018: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/30171681/synthesis-and-assembly-of-human-vault-particles-in-yeast
#15
Meng Wang, Valerie A Kickhoefer, Leonard H Rome, Oliver K Foellmer, Shaily Mahendra
Vault particles are the largest naturally occurring ribonucleoprotein complexes found in the cytoplasm. Seventy-eight copies of major vault protein (MVP) assemble on polyribosome templates, forming recombinant vault particles, which are of great interest as encapsulation carriers for therapeutics delivery and enzyme stabilization. Baculovirus-insect cell expression is the only system that has been developed for recombinant vault synthesis, but it has low scalability and slow production rate. In this work, we demonstrated the first use of yeast cells for the production of vault particles with full integrity and functionality solely by expressing the cDNA encoding MVP...
September 1, 2018: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/30144379/recurring-genomic-structural-variation-leads-to-clonal-instability-and-loss-of-productivity
#16
Arpan A Bandyopadhyay, Sofie A O'Brien, Liang Zhao, Hsu-Yuan Fu, Nandita Vishwanathan, Wei-Shou Hu
Chinese Hamster Ovary (CHO) cells, commonly used in the production of therapeutic proteins, are aneuploid. Their chromosomes bear structural abnormality and undergo changes in structure and number during cell proliferation. Some production cell lines are unstable and lose their productivity over time in the manufacturing process and during the product's life cycle. To better understand the link between the genome structural changes and productivity stability, an Immunoglobulin G (IgG) producing cell line was successively single-cell cloned to obtain subclones that retained or lost productivity, and their genomic features were compared...
August 25, 2018: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/30144353/neonatal-testis-growth-recreated-in-vitro-by-two-dimensional-organ-spreading
#17
Kazuaki Kojima, Hiroko Nakamura, Mitsuru Komeya, Hiroyuki Yamanaka, Yoshinori Makino, Yuki Okada, Haruhiko Akiyama, Nobuhito Torikai, Takuya Sato, Teruo Fujii, Hiroshi Kimura, Takehiko Ogawa
Organ culture experiments can be hampered by central degeneration or necrosis due to the inadequate permeation of oxygen and nutrients, which deteriorates the function and growth of cultured tissues. In the present study, we aimed to overcome this limitation of organ culture through spreading the tissue two-dimensionally on an agarose gel stand and molding into a disc-shape by placing a ceiling of polydimethylsiloxane (PDMS) chip, which is highly oxygen-permeable. By this, every part of the tissue can receive a sufficient supply of oxygen through PDMS as well as nutrients through the agarose gel below...
August 25, 2018: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/30144310/tissue-engineering-approaches-in-pancreatic-islet-transplantation
#18
REVIEW
M Perez-Basterrechea, M M Esteban, J A Vega, A J Obaya
Pancreatic islet transplantation is a promising alternative to whole-pancreas transplantation as a treatment for type 1 diabetes mellitus. This technique has been extensively developed during the past few years, with the main purpose of minimizing the complications arising from the standard protocols used in organ transplantation. By using a variety of strategies employed in tissue engineering and regenerative medicine, pancreatic islets have been successfully introduced in host patients with different outcomes in terms of islet survival and functionality, as well as the desired normoglycaemic control...
August 25, 2018: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/30132794/an-aptasensor-for-rapid-and-sensitive-detection-of-estrogen-receptor-alpha-in-human-breast-cancer
#19
Rajesh Ahirwar, Anita Dalal, Jai Gopal Sharma, Birendra Kumar Yadav, Pradip Nahar, Ashok Kumar, Saroj Kumar
Analysis of estrogen receptor (ER) expression in breast carcinomas plays a crucial role in determining the endocrine-responsiveness of tumors for systemic adjuvant therapy. Conventionally, the estrogen receptor levels in breast carcinomas had been detected using the dextran-coated charcoal (DCC) assays and radioimmunoassay (RIA), which are now substituted with safer and economic antibody-based assays like immunohistochemistry (IHC) and ELISA. Despite a gold standard method, the IHC has been criticized for factors such as tissue fixation, antibody selection, and threshold staining for result interpretation which could falsify test accuracy and reproducibility...
August 21, 2018: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/30132790/cellulases-adsorb-reversibly-on-biomass-lignin
#20
Demi T Djajadi, Ville Pihlajaniemi, Jenni Rahikainen, Kristiina Kruus, Anne S Meyer
Adsorption of cellulases onto lignin is considered a major factor in retarding enzymatic cellulose degradation of lignocellulosic biomass. However, the adsorption mechanisms and kinetics are not well understood for individual types of cellulases. This study examines the binding affinity, kinetics of adsorption, and competition of four monocomponent cellulases of Trichoderma reesei during adsorption onto lignin. TrCel7A, TrCel6A, TrCel7B and TrCel5A were radiolabeled for adsorption experiments on lignin-rich residues (LRRs) isolated from hydrothermally pretreated spruce (L-HPS) and wheat straw (L-HPWS), respectively...
August 21, 2018: Biotechnology and Bioengineering
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