38 results on '"Vu TL"'
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2. Investigation of User Performance in Virtual Reality-based Annotation-assisted Remote Robot Control
- Author
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Vu, TL, Nguyen, DDK, Sutjipto, S, Le, DT, and Paul, G
- Abstract
This poster investigates the use of point cloud processing algorithms to provide annotations for robotic manipulation tasks completed remotely via Virtual Reality (VR). A VR-based system has been developed that receives and visualizes the processed data from real-time RGB-D camera feeds. A real-world robot model has also been developed to provide realistic reactions and control feedback. The targets and the robot model are reconstructed in a VR environment and presented to users in different modalities. The modalities and available information are varied between experimental settings, and the associated task performance is recorded and analyzed. The results accumulated from 192 experiments completed by 8 participants showed that point cloud data is sufficient for completing the task. Additional information, either image stream or preliminary processes presented as annotations, was found to not have a significant impact on the completion time. However, the combination of image stream and colored point cloud data visualization modalities was found to greatly enhance a user's performance accuracy, with the number of target centers missed being reduced by 40%.
- Published
- 2022
3. Investigation of Annotation-assisted User Performance in Virtual Reality-based Remote Robot Control
- Author
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Vu, TL, Nguyen, DDK, Sutjipto, S, Le, DT, Paul, G, Vu, TL, Nguyen, DDK, Sutjipto, S, Le, DT, and Paul, G
- Abstract
This paper investigates the use of point cloud processing algorithms to provide annotations for robotic manipulation tasks completed remotely via Virtual Reality VR A VR based system has been developed that receives and visualises processed data from real time RGB D camera feeds A point cloud processing algorithm is introduced to annotate targets and simulated experiments were conducted to validate the efficacy of the proposed algorithm A real world robot model has also been developed to provide realistic reactions and control feedback The targets and the robot model are reconstructed in a VR environment and presented to users with different modalities The modalities and available information are varied between experimental settings and the associated task performance is recorded and analysed The results accumulated from 288 experiments completed by 12 participants indicated that point cloud data is sufficient for task completion Additional information neither image stream nor preliminary processes presented as annotations was found to have a signficant impact on the completion time However the combination of image stream and colored point cloud data visualisation modalities was found to greatly enhance a user s performance accuracy with the number of target centres missed being reduced by 25 2022 Australasian Robotics and Automation Association All rights reserved
- Published
- 2022
4. Investigating the effect of sensor data visualization variances in virtual reality
- Author
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Vu, TL, Le, DT, Nguyen, DDK, Sutjipto, S, and Paul, G
- Abstract
This paper investigates the effect of real-time sensor data variances on humans performing straightforward assembly tasks in a Virtual Reality-based (VR-based) training system. A VR-based training system has been developed to transfer color and depth images, and constructs colored point clouds data to represent objects in real-time. Various parameters that affect sensor data acquisition and visualization of remotely operated robots in the real-world are varied. Afterward, the associated task performance is observed. Experimental results from 12 participants performed a total of 95 VR-guided puzzle assembly tasks demonstrated that a combination of low resolution and uncolored points has the most significant effect on participants’ performance. Participants mentioned that they needed to rely upon tactile feedback when the perceptual feedback was minimal. The most insignificant parameter determined was the resolution of the data representations, which, when varied within the experimental bounds, only resulted in a 5% average change in completion time. Participants also indicated in surveys that they felt their performance had improved and frustration was reduced when provided with color information of the scene.
- Published
- 2021
5. Impact Factors in a Curriculum Vitae for Scholarship Application
- Author
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Mariam Abdelkhalek, Thanh Hoa Nt, Huong Quynh Tt, Cam Tien Tt, Sherief Ghozy, Giang Htn, Ahmed M Elshafie, Sa Ny, Iyad Al-Midani Om, Kim Anh Nt, Eldeen Ghorab Mm, Kieu Linh Dt, Kenji Hirayama, Nguyen Tien Huy, NT Long, Samar Salman, and Huy Vu Tl
- Subjects
Scholarship ,Medical education ,Impact factor ,Scopus ,General Medicine ,Error checking ,Psychology ,Citation ,Curriculum ,computer ,Delphi ,Advice (programming) ,computer.programming_language - Abstract
Introduction: Scholarship applicants often receive different advice on what should be included in their Curriculum Vitae (CV). This study aims to investigate what the essential components of a CV being prepared for scholarships are, how to present them, and what their level of impact is. Materials and Methods: The authors sent an online structured questionnaire to 7512 corresponding authors of recent published papers in Scopus; 124 completed questionnaires were returned. Recommended elements for a CV were chosen according to the Delphi consensus technique with a threshold of 50%. Results: This survey revealed that headings, bullet points and careful error checking were essential parts of the layout. For the content of the CV, besides publications, education and training background, research experience and research interest were also necessary. Moreover, almost all respondents ranked publications as the most important qualification of an academic scholarship candidate. Publications also came first as the most impressive factor, followed by awards and honours. The number of publications, quality of journal, impact factor and total citation should be presented in publication section. The importance of publications in getting academic scholarships is significantly emphasized in this recent study. Conclusions: Having research experience and papers in peer review journals, are highly recommended for students seeking academic scholarships.
- Published
- 2020
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6. Approaches for Efficiently Detecting Frontier Cells in Robotics Exploration.
- Author
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Quin, P, Nguyen, DDK, Vu, TL, Alempijevic, A, Paul, G, Quin, P, Nguyen, DDK, Vu, TL, Alempijevic, A, and Paul, G
- Abstract
Many robot exploration algorithms that are used to explore office, home, or outdoor environments, rely on the concept of frontier cells. Frontier cells define the border between known and unknown space. Frontier-based exploration is the process of repeatedly detecting frontiers and moving towards them, until there are no more frontiers and therefore no more unknown regions. The faster frontier cells can be detected, the more efficient exploration becomes. This paper proposes several algorithms for detecting frontiers. The first is called Naïve Active Area (NaïveAA) frontier detection and achieves frontier detection in constant time by only evaluating the cells in the active area defined by scans taken. The second algorithm is called Expanding-Wavefront Frontier Detection (EWFD) and uses frontiers from the previous timestep as a starting point for searching for frontiers in newly discovered space. The third approach is called Frontier-Tracing Frontier Detection (FTFD) and also uses the frontiers from the previous timestep as well as the endpoints of the scan, to determine the frontiers at the current timestep. Algorithms are compared to state-of-the-art algorithms such as Naïve, WFD, and WFD-INC. NaïveAA is shown to operate in constant time and therefore is suitable as a basic benchmark for frontier detection algorithms. EWFD and FTFD are found to be significantly faster than other algorithms.
- Published
- 2021
7. Active and Interactive Mapping With Dynamic Gaussian Process Implicit Surfaces for Mobile Manipulators
- Author
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Liu, L, Fryc, S, Wu, L, Vu, TL, Paul, G, Vidal-Calleja, T, Liu, L, Fryc, S, Wu, L, Vu, TL, Paul, G, and Vidal-Calleja, T
- Abstract
In this letter, we present an interactive probabilistic mapping framework for a mobile manipulator picking objects from a pile. The aim is to map the scene, actively decide where to go next and which object to pick, make changes to the scene by picking the chosen object, and then map these changes alongside. The proposed framework uses a novel dynamic Gaussian Process (GP) Implicit Surface method to incrementally build and update the scene map that reflects environment changes. Actively the framework computes the next-best-view, balancing the terms of object reachability for picking and map information gain (IG) for fidelity and coverage. To enforce a priority of visiting boundary segments over unknown regions, the IG formulation includes an uncertainty gradient-based frontier score by exploiting the GP kernel derivative. This leads to an efficient strategy that addresses the often conflicting requirement of unknown environment exploration and object picking exploitation given a limited execution horizon. We demonstrate the effectiveness of our framework with software simulation and real-life experiments.
- Published
- 2021
8. Rectangular-shaped object recognition and pose estimation
- Author
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Vu, TL, Liu, L, Paul, G, Vidal Calleja, T, Vu, TL, Liu, L, Paul, G, and Vidal Calleja, T
- Published
- 2019
9. Introducing a Novel Innovative Technique for the Recording and Interpretation of Dynamic Coronary Angiography.
- Author
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Nguyen T, Ngo K, Vu TL, Nguyen HQ, Pham DH, Kodenchery M, Zuin M, Rigatelli G, Nanjundappa A, and Gibson M
- Abstract
In the study of coronary artery disease (CAD), the mechanism of plaque formation and development is still an important subject for investigation. A limitation of current coronary angiography (CAG) is that it can only show static images of the narrowing of arterial channels without identifying the mechanism of the disease or predicting its progression or regression. To address this limitation, the CAG technique has been modified. The new approach emphasizes identifying and analyzing blood flow patterns, employing methodologies akin to those used by hydraulic engineers for fluid or gas movement through domestic or industrial pipes and pumps. With the new technique, various flow patterns and arterial phenomena-such as laminar, turbulent, antegrade, retrograde, and recirculating flow and potentially water hammer shock and vortex formation-are identified, recorded, and classified. These phenomena are then correlated with the presence of lesions at different locations within the coronary vasculature. The formation and growth of these lesions are explained from the perspective of fluid mechanics. As the pathophysiology of CAD and other cardiovascular conditions becomes clearer, new medical, surgical, and interventional treatments could be developed to reverse abnormal coronary flow dynamics and restore laminar flow, leading to improved clinical outcomes.
- Published
- 2024
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10. Enhanced prokaryotic expression, purification, and biological activities of human keratinocyte growth factor.
- Author
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Vu TL, Nguyen TKO, Song JA, Chong S, and Choe H
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- Humans, Cell Differentiation, Cell Proliferation, Fibroblast Growth Factors metabolism, Keratinocytes metabolism, MCF-7 Cells, Recombinant Proteins genetics, Recombinant Proteins isolation & purification, Recombinant Proteins pharmacology, Fibroblast Growth Factor 7 genetics, Fibroblast Growth Factor 7 pharmacology, Fibroblast Growth Factor 7 metabolism
- Abstract
Keratinocyte growth factor (KGF), also known as fibroblast growth factor 7 (FGF7), plays a critical role in embryonic development, cell proliferation, and differentiation. However, efficient production of recombinant KGF remains a challenge due to its low expression levels and high tendency for aggregation in Escherichia coli. This study aimed to enhance the expression and solubility of KGF by employing different protein tags-PDIb'a', MBP, and His-fused to the N-terminus of KGF. Among these, H-PDIb'a'-KGF demonstrated superior stability and was selected for large-scale production and purification. The purified KGF was confirmed through liquid chromatography with tandem mass spectrometry analysis, which showed an 81% fragment mass identification coverage. Biological activity assessments using human breast cancer MCF-7 cells indicated that purified KGF significantly increased cell proliferation, with an EC
50 of 6.4 ± 0.5 pM. Interestingly, PDIb'a' alone also exhibited a stimulatory effect on MCF-7 cells. Furthermore, the purified KGF enhanced the wound healing of HaCaT keratinocytes in a dose-dependent manner. These findings provide valuable insights into the efficient production and functional characterization of recombinant KGF for potential applications in therapeutic interventions., Competing Interests: Declaration of Competing Interest The authors declare no conflicting interests., (Copyright © 2024 Elsevier B.V. All rights reserved.)- Published
- 2024
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11. Efficient production of human interleukin-3 from Escherichia coli using protein disulfide isomerase b'a' domain.
- Author
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Nguyen TKO, Ryu D, Nguyen MQ, Ta HKK, Vu TL, and Choe H
- Subjects
- Humans, Maltose-Binding Proteins genetics, Maltose-Binding Proteins metabolism, Cell Line, Tumor, Solubility, Protein Disulfide-Isomerases metabolism, Protein Disulfide-Isomerases genetics, Escherichia coli genetics, Escherichia coli metabolism, Interleukin-3 metabolism, Interleukin-3 genetics, Recombinant Fusion Proteins genetics, Recombinant Fusion Proteins metabolism, Recombinant Fusion Proteins chemistry
- Abstract
Human interleukin-3 (IL3) is a multifunctional cytokine essential for both clinical and biomedical research endeavors. However, its production in Escherichia coli has historically been challenging due to its aggregation into inclusion bodies, requiring intricate solubilization and refolding procedures. This study introduces an innovative approach employing two chaperone proteins, maltose binding protein (MBP) and protein disulfide isomerase b'a' domain (PDIb'a'), as N-terminal fusion tags. Histidine tag (H) was added at the beginning of each chaperone protein gene for easy purification. This fusion of chaperone proteins significantly improved IL3 solubility across various E. coli strains and temperature conditions, eliminating the need for laborious refolding procedures. Following expression optimization, H-PDIb'a'-IL3 was purified using two chromatographic methods, and the subsequent removal of the H-PDIb'a' tag yielded high-purity IL3. The identity of the purified protein was confirmed through liquid chromatography coupled with tandem mass spectrometry analysis. Biological activity assays using human erythroleukemia TF-1 cells revealed a unique two-step stimulation pattern for both purified IL3 and the H-PDIb'a'-IL3 fusion protein, underscoring the protein's functional integrity and revealing novel insights into its cellular interactions. This study advances the understanding of IL3 expression and activity while introducing novel considerations for protein fusion strategies., (© 2024 The Authors. Biotechnology Journal published by Wiley‐VCH GmbH.)
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- 2024
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12. Novel Anti-Mesothelin Nanobodies and Recombinant Immunotoxins with Pseudomonas Exotoxin Catalytic Domain for Cancer Therapeutics.
- Author
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Nguyen MQ, Kim DH, Shim HJ, Ta HKK, Vu TL, Nguyen TKO, Lim JC, and Choe H
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- Animals, Mice, Humans, Exotoxins genetics, Exotoxins pharmacology, Exotoxins chemistry, Mesothelin, Catalytic Domain, Cell Line, Tumor, ADP Ribose Transferases genetics, ADP Ribose Transferases chemistry, ADP Ribose Transferases metabolism, Recombinant Fusion Proteins genetics, Recombinant Fusion Proteins pharmacology, Recombinant Fusion Proteins metabolism, Immunotoxins genetics, Immunotoxins pharmacology, Immunotoxins chemistry, Single-Domain Antibodies genetics, Single-Domain Antibodies pharmacology, Bacterial Toxins genetics, Bacterial Toxins chemistry, Bacterial Toxins metabolism, Antineoplastic Agents, Neoplasms drug therapy
- Abstract
Recombinant immunotoxins (RITs) are fusion proteins consisting of a targeting domain linked to a toxin, offering a highly specific therapeutic strategy for cancer treatment. In this study, we engineered and characterized RITs aimed at mesothelin, a cell surface glycoprotein overexpressed in various malignancies. Through an extensive screening of a large nanobody library, four mesothelin-specific nanobodies were selected and genetically fused to a truncated Pseudomonas exotoxin (PE24B). Various optimizations, including the incorporation of furin cleavage sites, maltose-binding protein tags, and tobacco etch virus protease cleavage sites, were implemented to improve protein expression, solubility, and purification. The RITs were successfully overexpressed in Escherichia coli , achieving high solubility and purity post-purification. In vitro cytotoxicity assays on gastric carcinoma cell lines NCI-N87 and AGS revealed that Meso(Nb2)-PE24B demonstrated the highest cytotoxic efficacy, warranting further characterization. This RIT also displayed selective binding to human and monkey mesothelins but not to mouse mesothelin. The competitive binding assays between different RIT constructs revealed significant alterations in IC
50 values, emphasizing the importance of nanobody specificity. Finally, a modification in the endoplasmic reticulum retention signal at the C-terminus further augmented its cytotoxic activity. Our findings offer valuable insights into the design and optimization of RITs, showcasing the potential of Meso(Nb2)-PE24B as a promising therapeutic candidate for targeted cancer treatment.- Published
- 2023
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13. Preliminary Consequences of Blood Pressure Management and Blood Homocysteine Levels with Perindopril in Newly Diagnosed Hypertensive Patients in the Vietnamese Population.
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Kim Tran S, Truong AB, Nguyen PH, Ngo TH, Vu TL, Dang Tran KD, Vo PM, Nguyen BT, Le Trong Huynh T, Nguyen KT, and Tran HD
- Abstract
Background: Perindopril is an ACE inhibitor that aids in both blood pressure regulation and homocysteine reduction., Objectives: Our study aimed to evaluate the results of controlling blood pressure and blood homocysteine levels by perindopril in patients with primary hypertension., Materials and Methods: A cross-sectional descriptive study with a longitudinal follow-up was conducted on 105 primary hypertensive patients treated with perindopril., Results: The results of our study showed that after 6 weeks of treatment with perindopril, the proportion of patients with the target blood pressure (BP) level accounted for 70.5%, the rate of grade 1 hypertension decreased from 61.0% to 25.7%, grade 2 blood pressure decreased from 17.1% to 3.8%, and there was no case of grade 3 hypertension. At the same time, we also found that the rate of BP control in the group of patients who controlled Hcy below a threshold of 15 μ mol/L was significantly higher than in the other group ( p < 0.05). Concerning the efficacy of decreasing homocysteine in blood, we discovered that after 6 weeks of treatment with perindopril, the proportion of patients with elevated homocysteine reduced considerably from 74.3% to 40% ( p < 0.05). In addition, the homocysteine concentration was 4.33 mol/L lower after treatment than before treatment (95% CI: 3.69-4.97) ( p < 0.05)., Conclusion: Perindopril helps control blood pressure and reduces blood homocysteine levels in patients with primary hypertension., Competing Interests: The authors declare that there are no conflicts of interest., (Copyright © 2023 Son Kim Tran et al.)
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- 2023
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14. Study on the Anticancer Activity of Prodigiosin from Variants of Serratia Marcescens QBN VTCC 910026.
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Nguyen SLT, Nguyen TC, Do TT, Vu TL, Nguyen TT, Do TT, Nguyen THT, Le TH, Trinh DK, and Nguyen TAT
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- Animals, Anti-Bacterial Agents pharmacology, Antifungal Agents metabolism, Mice, Secondary Metabolism, Prodigiosin metabolism, Prodigiosin pharmacology, Serratia marcescens chemistry
- Abstract
Prodigiosin (Pg), a secondary metabolism produced by numerous bacterial species, is known as anticancer, antibacterial, antifungal, immunosuppressant, antioxidant, antimalarial properties. Pg has been tested for antitumor activity in many different cancer cell lines but studies in LU-1, KB cell lines, and tumor-bearing mice are still limited. In this study, Serratia marcescens QBN VTCC 910026 strain (GenBank: KX674054.1) was mutated using Ethyl Methanesulfonate (EMS) to increase the production of Pg. One strain known as EMS 5 was capable of increasing prodigiosin biosynthetic yield by 52% when compared to the wild-type strain. Red bacterial pigmented colonies containing Pg were collected from solid media, lysed with acetone, purified with toluene: ethyl acetate at a ratio of 9: 1 (v/v), and then used to evaluate the potential anticancer activity. The purity of Pg was confirmed using a high-performance liquid chromatography (HPLC) method which indicated a 98% rate. Pg chemical formula which was determined using
1 H-NMR and13 C-NMR spectroscopy, confirmed as prodigiosin (Pg). Human breast cancer cell lines MCF-7, oropharyngeal cancer KB, and particularly lung cancer LU-1 in vitro were used to test the anticancer activity of purified Pg compound. It showed a strong inhibitory ability in all the cancer cell lines. Furthermore, the isolated Pg had capable of inhibiting tumor growth, the tumor volume decreased by 36.82%, after 28 days. The results indicated that the bacterial prodigiosin from variants Serratia marcescens QBN VTCC 910026 strain is an encouraging fragment suitable for therapeutic applications., Competing Interests: The author(s) declare(s) that they have no conflicts of interest., (Copyright © 2022 Sy Le Thanh Nguyen et al.)- Published
- 2022
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15. Experimental characterization of bending effects for solid and hollow dielectric waveguides at V-band.
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Vu TL, Barlerin S, Stricot Y, Sauleau R, Ettorre M, and González-Ovejero D
- Abstract
Mm-wave dielectric waveguides are a promising and low-cost technology for the transmission of ultra-high data rates. Besides the attenuation (losses) and group delay, the bending loss of the dielectric waveguides is also one of the key parameters to establish the capacity and energy efficiency of such wired links, when deployed in realistic scenarios. In this context, we report the experimental characterizations of bending effects for various solid and hollow commercially available dielectric waveguides at V-band (50-75 GHz). A wide-band transition has been designed to carry out the measurements using a Vector Network Analyzer (VNA) and extension modules. The measured results are in very good agreement with full-wave simulations. Our experimental results show an average bending loss of 1.46 dB over the entire V-band for the fundamental [Formula: see text] mode of a PTFE solid dielectric waveguide (core diameter of 3.06 mm) with a 90° bending angle and 25 mm radius of curvature. This value rises up to 2.88 dB (or 3.25 dB) when bending radius is changed to 15 mm (or bending angle grows up to 140°). The measurements also show that the measured bending losses increase significantly for hollow dielectric waveguides, in particular when the inner to outer diameter ratio gets larger., (© 2021. The Author(s).)
- Published
- 2021
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16. Effects of size polydispersity on segregation of spherical particles in rotating drum.
- Author
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Vo TT, Vu TL, and Mutabaruka P
- Abstract
To get insight into the segregation process of a polydisperse granular materials flow, we numerically investigated the migration process of particles in a rotating drum operating in the rolling regime by means of the discrete element method. Particle migration is analyzed through the variation of the proportion of particles in different zones where the flow property is characterized. The proportion of particles in different zones of the drum shows to increase in the center of the flow radially and axially where a higher concentration of small particles is observed, while its decreases in other zones with a higher concentration of larger particles. Interestingly, we find that the migration process of particles leads to radial and axial segregation which is caused by a combination between the exerted fluctuation forces on particles and its surrounding pressure gradient.
- Published
- 2021
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17. Soluble Prokaryotic Overexpression and Purification of Human GM-CSF Using the Protein Disulfide Isomerase b'a' Domain.
- Author
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Nguyen TKO, Vu TL, Nguyen MQ, Ta HKK, Park KS, Kim SH, Kim CJ, Jang YJ, and Choe H
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- Cell Differentiation, Electrophoresis, Polyacrylamide Gel methods, Granulocyte-Macrophage Colony-Stimulating Factor metabolism, Hematopoietic Stem Cells metabolism, Humans, Maltose-Binding Proteins metabolism, Prokaryotic Cells metabolism, Protein Disulfide-Isomerases physiology, Protein Transport, Solubility, Chromatography, Gel methods, Granulocyte-Macrophage Colony-Stimulating Factor isolation & purification, Protein Disulfide-Isomerases metabolism
- Abstract
Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a member of the colony-stimulating factor (CSF) family, which functions to enhance the proliferation and differentiation of hematopoietic stem cells and other hematopoietic lineages such as neutrophils, dendritic cells, or macrophages. These proteins have thus generated considerable interest in clinical therapy research. A current obstacle to the prokaryotic production of human GM-CSF (hGM-CSF) is its low solubility when overexpressed and subsequent complex refolding processes. In our present study, the solubility of hGM-CSF was examined when combined with three N-terminal fusion tags in five E. coli strains at three different expression temperatures. In the five E. coli strains BL21 (DE3), ClearColi BL21 (DE3), LOBSTR, SHuffle T7 and Origami2 (DE3), the hexahistidine-tagged hGM-CSF showed the best expression but was insoluble in all cases at each examined temperature. Tagging with the maltose-binding protein (MBP) and the b'a' domain of protein disulfide isomerase (PDIb'a') greatly improved the soluble overexpression of hGM-CSF at 30 °C and 18 °C. The solubility was not improved using the Origami2 (DE3) and SHuffle T7 strains that have been engineered for disulfide bond formation. Two conventional chromatographic steps were used to purify hGM-CSF from the overexpressed PDIb'a'-hGM-CSF produced in ClearColi BL21 (DE3). In the experiment, 0.65 mg of hGM-CSF was isolated from a 0.5 L flask culture of these E. coli and showed a 98% purity by SDS-PAGE analysis and silver staining. The bioactivity of this purified hGM-CSF was measured at an EC
50 of 16.4 ± 2 pM by a CCK8 assay in TF-1 human erythroleukemia cells.- Published
- 2021
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18. Morbidity and Mortality Patterns in Children Admitted to Hospital in Thai Binh, Vietnam: A Five-year Descriptive Study with a Focus on Infectious Diseases.
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Pham TD, Hoang VT, Dao TL, Tran XD, Phi DL, To MM, Dang VN, Dang VK, Dao TT, Nguyen NT, Vu TT, Nguyen DT, Nguyen DC, Hoang NT, Vu TL, Nguyen TMC, Minodier P, and Gautret P
- Subjects
- Child, Child, Preschool, Hospitals, Pediatric, Humans, Infant, Infant, Newborn, Retrospective Studies, Vietnam epidemiology, Child Mortality trends, Communicable Diseases epidemiology, Communicable Diseases mortality, Communicable Diseases therapy, Hospitalization statistics & numerical data, Morbidity trends
- Abstract
The objective of this study was to describe the overall pattern of morbidity and mortality of children seen at the Thai Binh Paediatric Hospital in Vietnam, with a focus on infectious diseases. A retrospective review of hospitalisation records was conducted from 1 January 2015 to 31 December 2019. Data were obtained from a total of 113,999 records. The median age of patients was 18 months, with 84.0% of patients aged <5 years. Infectious diseases accounted for 61.0% of all cases. The most prevalent diseases were lower respiratory tract infections (32.8%), followed by gastrointestinal infections (13.3%) and confirmed influenza (5.4%). Most infections were not microbiologically documented. A total of 81.4% patients received at least one antibiotic. Most patients (97.0%) were hospitalised for less than 15 days. Regarding outcomes, 87.8% patients were discharged home with a favourable outcome. Twelve percent were transferred to the Vietnam National Children's Hospital because their condition had worsened and 0.1% died. In total, infectious diseases accounted for 40.4% of deaths, followed by neonatal disorders (34.6%). Our data serves a basis for the identification of needs for diagnostic tools and for future evaluation of the effect of the targeted implementation of such facilities. Point-of-care tests, including real-time polymerase chain reaction assays to identify common pathogens should be implemented for more accurate diagnosis and more appropriate antibiotic use., Competing Interests: The authors declare they have no conflicts of interest., (© 2020 The Authors. Published by Atlantis Press International B.V.)
- Published
- 2021
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19. Approaches for Efficiently Detecting Frontier Cells in Robotics Exploration.
- Author
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Quin P, Nguyen DDK, Vu TL, Alempijevic A, and Paul G
- Abstract
Many robot exploration algorithms that are used to explore office, home, or outdoor environments, rely on the concept of frontier cells. Frontier cells define the border between known and unknown space. Frontier-based exploration is the process of repeatedly detecting frontiers and moving towards them, until there are no more frontiers and therefore no more unknown regions. The faster frontier cells can be detected, the more efficient exploration becomes. This paper proposes several algorithms for detecting frontiers. The first is called Naïve Active Area (NaïveAA) frontier detection and achieves frontier detection in constant time by only evaluating the cells in the active area defined by scans taken. The second algorithm is called Expanding-Wavefront Frontier Detection (EWFD) and uses frontiers from the previous timestep as a starting point for searching for frontiers in newly discovered space. The third approach is called Frontier-Tracing Frontier Detection (FTFD) and also uses the frontiers from the previous timestep as well as the endpoints of the scan, to determine the frontiers at the current timestep. Algorithms are compared to state-of-the-art algorithms such as Naïve, WFD, and WFD-INC. NaïveAA is shown to operate in constant time and therefore is suitable as a basic benchmark for frontier detection algorithms. EWFD and FTFD are found to be significantly faster than other algorithms., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Quin, Nguyen, Vu, Alempijevic and Paul.)
- Published
- 2021
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20. Taxonomical insights and ecology of sandfly (Diptera, Psychodidae) species in six provinces of Northern Vietnam.
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Vu SN, Tran HS, Tran VP, Tran CT, Tran ND, Dang DA, Nguyen TY, Vu TL, Ngo KP, Nguyen VH, Hoàng NA, Cassan C, Prudhomme J, Depaquit J, Rahola N, and Bañuls AL
- Subjects
- Animals, Dogs, Ecology, Female, Male, Vietnam epidemiology, Leishmaniasis, Phlebotomus, Psychodidae
- Abstract
We studied sandfly (Diptera: Psychodidae) populations in six provinces of Vietnam. This work explores the diversity of sandfly species according to the province, as well as environment, and updated information on public health since leishmaniasis cases were reported in two provinces. Sandflies were collected using 428 CDC light traps from May 30 to October 13, 2016 and identified based on the morphology of the cibarium, pharynx and/or male genitalia or female spermathecae. A total of 2585 sandflies belonging to five genera and 13 identified species were collected. The main species were: the Sergentomyia barraudi group (12.53%), Se. sylvatica (9.63%) and Phlebotomus stantoni (3.95%). In all, 294 Sergentomyia specimens classified as Se. sp2 and Se. sp3 and a heterogeneous group, herein called Se. und_sp., showed unknown morphological characteristics requiring further studies. We provide detailed comments about morphological description and taxonomical identification in order to help standardization of sandfly classification in Southeast Asia. We observed differentiation according to the provinces in terms of density and species richness, with Lang Son having the highest density and Ninh Binh having the highest species richness. The majority of specimens were collected in rock caves and outdoors, suggesting mainly cavernicolous and exophilic characters of sandfly species in Northern Vietnam. However, specimens were also collected in intra- and peri-domiciliary sites. It is worth noting that Ph. stantoni was the main species found in dog sheds and indoors, and in particular in a leishmaniasis patient's house., (© S.N. Vu et al., published by EDP Sciences, 2021.)
- Published
- 2021
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21. Compaction of elastic granular materials: inter-particles friction effects and plastic events.
- Author
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Vu TL, Nezamabadi S, and Mora S
- Abstract
The uni-axial compaction of granular materials made of elastic neo-Hookean particles is investigated in the quasi-static regime. Two-dimensional disk assemblies are simulated using the Finite Element model coupled with Contact Dynamics method for dealing both with finite deformations of the particles and contact interactions. Due to large deformations of the particles, the packing fraction of the system increases continuously during the compaction process, reaching values close to 1. The influence of the coefficient of friction between the particles on the macroscopic and micro-structural behaviors of the system is thoroughly discussed.
- Published
- 2020
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22. Soft-grain compression: Beyond the jamming point.
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Vu TL and Barés J
- Abstract
We present the experimental studies of highly strained soft bidisperse granular systems made of hyperelastic and plastic particles. We explore the behavior of granular matter deep in the jammed state from local field measurement from the grain scale to the global scale. By means of a dedicated digital image correlation code and an accurate image recording method, we measure for each compression step the evolution of the particle geometries and their right Cauchy-Green strain tensor fields. We analyze the evolution of the usual macroscopic observables (stress, packing fraction, coordination, fraction of nonrattlers, etc.) along the compression process through the jamming point and far beyond. Analyzing the evolution of the local strain statistics, we evidence a crossover in the material behavior deep in the jammed state for both sorts of particles. We show that this crossover is due to a competition between material compression, dilation, and shear, so its position depends on the particle material. We argue that the strain field is a reliable observable to describe the evolution of a granular system through the jamming transition and deep in the dense packing state whatever the material behavior.
- Published
- 2019
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23. Numerical simulations of the compaction of assemblies of rubberlike particles: A quantitative comparison with experiments.
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Vu TL, Barés J, Mora S, and Nezamabadi S
- Abstract
Using the contact dymanics method together with the finite element method, we simulate the uniaxial compression of assemblies of elastic cylinders. The numerical model accounts for finite deformations of the particles through the neo-Hookean constitutive equation and solid friction between the particles. A quantitative comparison with experiments carried out with centimetric rubberlike cylinders, with local deformations of the particles determined by image correlation, is proposed. We show that the simulations accurately capture the details of both the microstructure and the macroscopic behavior of the real granular system, demonstrating the relevancy of the numerical approach.
- Published
- 2019
- Full Text
- View/download PDF
24. Synthesis, Characterization, and Modification of Alumina Nanoparticles for Cationic Dye Removal.
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Chu TPM, Nguyen NT, Vu TL, Dao TH, Dinh LC, Nguyen HL, Hoang TH, Le TS, and Pham TD
- Abstract
In the present study, alumina nanoparticles (nano-alumina) which were successfully fabricated by solvothermal method, were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Transmission Electron Microscopy (TEM), and Brunauer⁻Emmett⁻Teller (BET) methods. The removal of cationic dye, Rhodamine B (RhB), through adsorption method using synthesized nano-alumina with surface modification by anionic surfactant was also investigated. An anionic surfactant, sodium dodecyl sulfate (SDS) was used to modify nano-alumina surface at low pH and high ionic strength increased the removal efficiency of RhB significantly. The optimum adsorption conditions of contact time, pH, and adsorbent dosage for RhB removal using SDS modified nano-alumina (SMNA) were found to be 120 min, pH 4, and 5 mg/mL respectively. The RhB removal using SMNA reached a very high removal efficiency of 100%. After four times regeneration of adsorbent, the removal efficiency of RhB using SMNA was still higher than 86%. Adsorption isotherms of RhB onto SMNA at different salt concentrations were fitted well by a two-step model. A very high adsorption capacity of RhB onto SMNA of 165 mg/g was achieved. Adsorption mechanisms of RhB onto SMNA were discussed on the basis of the changes in surface modifications, the change in surface charges and adsorption isotherms.
- Published
- 2019
- Full Text
- View/download PDF
25. Methylation Profiles of BRCA1, RASSF1A and GSTP1 in Vietnamese Women with Breast Cancer
- Author
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Vu TL, Nguyen TT, Doan VTH, and Vo LTT
- Subjects
- Breast Neoplasms epidemiology, Breast Neoplasms pathology, Case-Control Studies, Female, Follow-Up Studies, Humans, Middle Aged, Prognosis, Promoter Regions, Genetic, Vietnam epidemiology, Asian People genetics, BRCA1 Protein genetics, Biomarkers, Tumor genetics, Breast Neoplasms genetics, DNA Methylation, Glutathione S-Transferase pi genetics, Tumor Suppressor Proteins genetics
- Abstract
Objective: This study investigated the DNA promoter methylation profiles of BRCA1, RASSF1A and GSTP1 genes, both individually and in an integrative manner in order to clarify their correlation with clinicopathological parameters of breast cancer from Vietnamese patients, and establish new potential integrative methylation biomarkers for breast cancer detection. Material and methods: The methylation frequencies of BRCA1, RASSF1A and GSTP1 were analyzed by methylation specific polymerase chain reaction (MSP) in 70 specimens of breast carcinomas and 79 pairs of tumor and matched adjacent normal tissues from breast cancer patients. Results: All the three analyzed genes showed a concordance concerning their promoter methylation in tumor and adjacent normal tissue. The methylation of BRCA1, RASSF1A and GSTP1 was found in 58.23 %, 74.68 % and 59.49 % of tumor tissues and 51.90 %, 63.29 % and 35.44 % of corresponding adjacent tissues, respectively. When each gene was assessed individually, only the methylation of GSTP1 was significantly associated with tumor tissues (p=0.003). However, the methylation frequency of at least one of the three genes and the methylation frequency of all the three genes both showed significant association with tumor (p=0.008 and p=0.04, respectively). The methylation of BRCA1 was found to be significantly associated with tumor grade (p=0.01). Conclusion: This study emphasized that the panel of the three genes BRCA1, RASSF1A and GSTP1 can be further developed as potential biomarkers in diagnosis and classification of breast cancer in Vietnamese women., (Creative Commons Attribution License)
- Published
- 2018
- Full Text
- View/download PDF
26. Medicinal plants for in vitro antiplasmodial activities: A systematic review of literature.
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Lemma MT, Ahmed AM, Elhady MT, Ngo HT, Vu TL, Sang TK, Campos-Alberto E, Sayed A, Mizukami S, Na-Bangchang K, Huy NT, Hirayama K, and Karbwang J
- Subjects
- Humans, Antimalarials therapeutic use, Malaria drug therapy, Plants, Medicinal chemistry, Plasmodium drug effects
- Abstract
The increasing resistance of malaria to drugs raise the need to new antimalarial agents. Antiplasmodial herbs and their active compounds are the most promising source the new antimalarial agents. This study aimed to identify the medicinal plants with very good in vitro antiplasmodial activities, with half-maximal inhibitory concentration (IC
50 )≤1μg/ml, and to determine trends in the process of screening their antiplasmodial activities. A total of 58 reports published in the English language were retrieved from the bibliographical databases. Screening and data extraction were performed by two independent reviewers. The herbs were categorized as very good, good, moderate and inactive if the IC50 values were <0.1μg/ml, 0.1-1μg/ml, >1-5μg/ml and >5μg/ml respectively. We documented 752 medicinal plants belonging to 254 genera. The majority of the plants were reported from Africa followed by Asia. The traditional use for malaria treatment was the most common reason for the selection of the plants for investigation. About 80% of the plants experimented were reported to be inactive. Among plants identified as having very good to good antiplasmodial crude extracts are Harungana madagascariensis, Quassia africana, and Brucea javanica, while Picrolemma spruce, Aspidosperma vargasi, Aspidosperma desmanthum, and Artemisia annua were reported to have individual compound isolates with very good antiplasmodial activities. In conclusion, the number of plant species assessed so far is still small compared with the stock in nature's plant library. A mechanism of systematically approaching and exploring the untouched plant genera needs to be designed., (Copyright © 2017 Elsevier B.V. All rights reserved.)- Published
- 2017
- Full Text
- View/download PDF
27. Early vaccination protects against childhood leukemia: A systematic review and meta-analysis.
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Morra ME, Kien ND, Elmaraezy A, Abdelaziz OAM, Elsayed AL, Halhouli O, Montasr AM, Vu TL, Ho C, Foly AS, Phi AP, Abdullah WM, Mikhail M, Milne E, Hirayama K, and Huy NT
- Subjects
- Haemophilus Vaccines therapeutic use, Hepatitis B Vaccines therapeutic use, Humans, Measles-Mumps-Rubella Vaccine therapeutic use, Leukemia immunology, Leukemia prevention & control, Vaccination methods, Vaccines, Combined therapeutic use
- Abstract
Leukemia is the most commonly diagnosed childhood cancer, although its etiology is still largely unknown. Growing evidence supports a role for infection in the etiology of acute lymphocytic leukemia (ALL), and the involvement of the immune system suggests that vaccination may also play a role. However, the findings presented in the published literature are inconsistent. Therefore, we conducted a PRISMA systematic review and meta-analysis. 14 studies were identified and meta-analyzed. Vaccinations studied comprised Bacillus Calmette-Guérin (BCG) vaccine, Triple vaccine, Hepatitis B vaccine (HBV), Polio, Measles, Rubella, Mumps, trivalent MMR vaccine and Haemophilus influenza type B (HiB) vaccine. We observed a protective association between any vaccination in the first year of life and risk of childhood leukemia (summary odds ratio (OR) 0.58 [95% confidence interval (CI) 0.36-0.91]). When individual vaccines were analysed, some evidence of an association was seen only for BCG (summary OR 0.73 [95% CI 0.50-1.08]). In conclusion, early vaccination appears to be associated with a reduced risk of childhood leukemia. This finding may be underpinned by the association observed for BCG. Given the relatively imprecise nature of the results of this meta-analysis, our findings should be interpreted cautiously and replicated in future studies.
- Published
- 2017
- Full Text
- View/download PDF
28. Definition of "persistent vomiting" in current medical literature: A systematic review.
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Morra ME, Elshafay A, Kansakar AR, Mehyar GM, Dang NPH, Mattar OM, Iqtadar S, Mostafa MR, Hai VN, Vu TL, Ghazy AA, Kaboub F, Huy NT, and Hirayama K
- Subjects
- Humans, Time Factors, Terminology as Topic, Vomiting physiopathology
- Abstract
Background and Aim: Persistent vomiting is mentioned as a symptom of a large variety of systemic disorders. It is commonly used interchangeably with chronic, recurrent, or intractable vomiting and widely used as a warning sign of severe illness in dengue infection. However, it has been poorly defined in the medical literature. Therefore, we aimed to systematically review a definition of persistent vomiting in the medical literature., Methods: A systematic search was done through; PubMed, Google Scholar, Web of Science, Scopus, VHL, WHO-GHL, Grey Literature Report, POPLINE, and SIGLE for the last 10 years. Consensus on the definition was considered to be reached if at least 50% of studies described the same definition using the Delphi consensus technique., Result: Of 2362 abstracts reviewed, 15 studies were selected based on the inclusion criteria. Three studies used the same definition. Another 2 studies defined it as vomiting of all foods and fluid in 24 hours. Three studies defined persistent vomiting in the units of days or weeks. Four studies used the number of episodes: ≥2 episodes 15 minutes apart, >3 episodes in 12 hours, and >3 episodes within 24 hours., Conclusion: No consensus for the definition was found among authors. This is a point of concern that needs to be addressed by further studies.
- Published
- 2017
- Full Text
- View/download PDF
29. The changing characteristics and molecular profiles of papillary thyroid carcinoma over time: a systematic review.
- Author
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Vuong HG, Altibi AM, Abdelhamid AH, Ngoc PU, Quan VD, Tantawi MY, Elfil M, Vu TL, Elgebaly A, Oishi N, Nakazawa T, Hirayama K, Katoh R, Huy NT, and Kondo T
- Subjects
- Adult, Carcinoma, Papillary pathology, Chi-Square Distribution, Female, Gene Rearrangement, Genes, ras, Genetic Predisposition to Disease, Humans, Male, Middle Aged, Mutation, Phenotype, Proto-Oncogene Proteins B-raf genetics, Proto-Oncogene Proteins c-ret genetics, Risk Factors, Thyroid Cancer, Papillary, Thyroid Neoplasms pathology, Time Factors, Transcriptome, Biomarkers, Tumor genetics, Carcinoma, Papillary genetics, Thyroid Neoplasms genetics
- Abstract
Background: The genetic alterations of papillary thyroid carcinoma (PTC) have been reported to change over the past few decades. We performed this systematic review to further examine the trends and modifications of patient demographic, clinicopathological features and molecular profiles of PTC over time., Methods: A literature search was performed within six electronic databases to identify relevant articles. The inclusion criteria were published studies investigating BRAF mutations, RET/PTC rearrangements or RAS mutations in PTCs or classical PTCs. Two teams of reviewers independently screened titles and abstracts of all articles. Full texts of potential articles were read and extracted data were listed and stratified into an excel file according to country, city, institution, and surgical time period. Student t test and Pearson Chi-square were used to analyze the trends of demographic and clinicopathological features of PTC patients and the prevalence of each genetic alteration in individual institutions., Results: From 3139 articles, we included 16 articles for final analysis. Our results showed an increasing trend of BRAF and a decreasing trend of RET/PTC prevalence over time in PTCs and classical PTCs, accompanied by an older age of PTC patients, an increase in proportion of PTMC and less aggressive behaviours of tumours., Conclusions: The demographic and clinicopathological characteristics and molecular profile of PTCs have been changing over the past few decades. These modifications suggest changes in etiologies and risk factors of thyroid cancer that influence the tumorigenesis of PTCs.
- Published
- 2017
- Full Text
- View/download PDF
30. Therapeutic efficacy and safety of Botulinum Toxin A Therapy in Trigeminal Neuralgia: a systematic review and meta-analysis of randomized controlled trials.
- Author
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Morra ME, Elgebaly A, Elmaraezy A, Khalil AM, Altibi AM, Vu TL, Mostafa MR, Huy NT, and Hirayama K
- Subjects
- Botulinum Toxins, Type A adverse effects, Botulinum Toxins, Type A pharmacology, Databases, Factual, Edema chemically induced, Hematoma chemically induced, Humans, Pain Measurement drug effects, Pain Measurement methods, Quality of Life, Treatment Outcome, Trigeminal Neuralgia epidemiology, Botulinum Toxins, Type A therapeutic use, Randomized Controlled Trials as Topic methods, Trigeminal Neuralgia diagnosis, Trigeminal Neuralgia drug therapy
- Abstract
Background: Several different interventions have been examined to alleviate pain and reduce frequency of trigeminal neuralgia (TN) paroxysms. However, some patients continue to have persistent or recurrent painful attacks. Using a systematic review and meta-analysis approach, we aimed to synthesize evidence from published randomized controlled trials (RCTs) regarding safety and efficacy of botulinum toxin type A (BTX-A) as a possible emerging choice of treatment for TN., Methods: We conducted an electronic search in 10 databases/electronic search engines to access relevant publications. All articles in all languages reporting RCTs on the efficacy and safety of BTX-A in the treatment of TN were included for systematic review and meta-analysis., Results: A total of four RCTs (n = 178) were identified for final meta-analysis. The overall effect favored BTX-A versus placebo in terms of proportion of responders (risk ratio RR = 2.87, 95 % confidence interval CI [1.76, 4.69], p <0.0001) with no significant detected heterogeneity (p = 0.31; I(2) = 4 %). Paroxysms frequency per day was significantly lower for BTX-A group (mean difference MD = -29.79, 95 % CI [-38.50,-21.08], p <0.00001) with no significant heterogeneity (p = 0.21; I(2) = 36 %)., Conclusion: Despite limited data, our results suggest that BTX-A may be an effective and safe treatment option for patients with TN. Further larger and well-designed RCTs are encouraged to translate these findings into better clinical outcome and better quality of life for TN patients.
- Published
- 2016
- Full Text
- View/download PDF
31. Infused polymers for cell sheet release.
- Author
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Juthani N, Howell C, Ledoux H, Sotiri I, Kelso S, Kovalenko Y, Tajik A, Vu TL, Lin JJ, Sutton A, and Aizenberg J
- Subjects
- Animals, Cell Line, Mesenchymal Stem Cells physiology, Mice, Oils, Fibronectins metabolism, Tissue Engineering methods, Tissue Scaffolds
- Abstract
Tissue engineering using whole, intact cell sheets has shown promise in many cell-based therapies. However, current systems for the growth and release of these sheets can be expensive to purchase or difficult to fabricate, hindering their widespread use. Here, we describe a new approach to cell sheet release surfaces based on silicone oil-infused polydimethylsiloxane. By coating the surfaces with a layer of fibronectin (FN), we were able to grow mesenchymal stem cells to densities comparable to those of tissue culture polystyrene controls (TCPS). Simple introduction of oil underneath an edge of the sheet caused it to separate from the substrate. Characterization of sheets post-transfer showed that they retain their FN layer and morphology, remain highly viable, and are able to grow and proliferate normally after transfer. We expect that this method of cell sheet growth and detachment may be useful for low-cost, flexible, and customizable production of cellular layers for tissue engineering.
- Published
- 2016
- Full Text
- View/download PDF
32. Hierarchical structural control of visual properties in self-assembled photonic-plasmonic pigments.
- Author
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Koay N, Burgess IB, Kay TM, Nerger BA, Miles-Rossouw M, Shirman T, Vu TL, England G, Phillips KR, Utech S, Vogel N, Kolle M, and Aizenberg J
- Subjects
- Color, Coloring Agents analysis, Nanostructures chemistry, Photons, Silicon Dioxide chemistry
- Abstract
We present a simple one-pot co-assembly method for the synthesis of hierarchically structured pigment particles consisting of silica inverse-opal bricks that are doped with plasmonic absorbers. We study the interplay between the plasmonic and photonic resonances and their effect on the visual appearance of macroscopic collections of photonic bricks that are distributed in randomized orientations. Manipulating the pore geometry tunes the wavelength- and angle-dependence of the scattering profile, which can be engineered to produce angle-dependent Bragg resonances that can either enhance or contrast with the color produced by the plasmonic absorber. By controlling the overall dimensions of the photonic bricks and their aspect ratios, their preferential alignment can either be encouraged or suppressed. This causes the Bragg resonance to appear either as uniform color travel in the former case or as sparse iridescent sparkle in the latter case. By manipulating the surface chemistry of these photonic bricks, which introduces a fourth length-scale (molecular) of independent tuning into our design, we can further engineer interactions between liquids and the pores. This allows the structural color to be maintained in oil-based formulations, and enables the creation of dynamic liquid-responsive images from the pigment.
- Published
- 2014
- Full Text
- View/download PDF
33. A bioinspired omniphobic surface coating on medical devices prevents thrombosis and biofouling.
- Author
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Leslie DC, Waterhouse A, Berthet JB, Valentin TM, Watters AL, Jain A, Kim P, Hatton BD, Nedder A, Donovan K, Super EH, Howell C, Johnson CP, Vu TL, Bolgen DE, Rifai S, Hansen AR, Aizenberg M, Super M, Aizenberg J, and Ingber DE
- Subjects
- Animals, Biofilms drug effects, Catheters microbiology, Equipment and Supplies microbiology, Humans, Surface Properties, Swine, Biofouling prevention & control, Coated Materials, Biocompatible therapeutic use, Thrombosis prevention & control
- Abstract
Thrombosis and biofouling of extracorporeal circuits and indwelling medical devices cause significant morbidity and mortality worldwide. We apply a bioinspired, omniphobic coating to tubing and catheters and show that it completely repels blood and suppresses biofilm formation. The coating is a covalently tethered, flexible molecular layer of perfluorocarbon, which holds a thin liquid film of medical-grade perfluorocarbon on the surface. This coating prevents fibrin attachment, reduces platelet adhesion and activation, suppresses biofilm formation and is stable under blood flow in vitro. Surface-coated medical-grade tubing and catheters, assembled into arteriovenous shunts and implanted in pigs, remain patent for at least 8 h without anticoagulation. This surface-coating technology could reduce the use of anticoagulants in patients and help to prevent thrombotic occlusion and biofouling of medical devices.
- Published
- 2014
- Full Text
- View/download PDF
34. Self-replenishing vascularized fouling-release surfaces.
- Author
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Howell C, Vu TL, Lin JJ, Kolle S, Juthani N, Watson E, Weaver JC, Alvarenga J, and Aizenberg J
- Subjects
- Biofilms drug effects, Cell Count, Dimethylpolysiloxanes pharmacology, Lubricants toxicity, Microalgae cytology, Microalgae drug effects, Plant Vascular Bundle drug effects, Silicones pharmacology, Surface Properties, Toxicity Tests, Biofouling, Plant Vascular Bundle physiology
- Abstract
Inspired by the long-term effectiveness of living antifouling materials, we have developed a method for the self-replenishment of synthetic biofouling-release surfaces. These surfaces are created by either molding or directly embedding 3D vascular systems into polydimethylsiloxane (PDMS) and filling them with a silicone oil to generate a nontoxic oil-infused material. When replenished with silicone oil from an outside source, these materials are capable of self-lubrication and continuous renewal of the interfacial fouling-release layer. Under accelerated lubricant loss conditions, fully infused vascularized samples retained significantly more lubricant than equivalent nonvascularized controls. Tests of lubricant-infused PDMS in static cultures of the infectious bacteria Staphylococcus aureus and Escherichia coli as well as the green microalgae Botryococcus braunii, Chlamydomonas reinhardtii, Dunaliella salina, and Nannochloropsis oculata showed a significant reduction in biofilm adhesion compared to PDMS and glass controls containing no lubricant. Further experiments on vascularized versus nonvascularized samples that had been subjected to accelerated lubricant evaporation conditions for up to 48 h showed significantly less biofilm adherence on the vascularized surfaces. These results demonstrate the ability of an embedded lubricant-filled vascular network to improve the longevity of fouling-release surfaces.
- Published
- 2014
- Full Text
- View/download PDF
35. [Obtaining homogenous preparations of succinate dehydrogenase isoforms from the D-507 strain of Sphaerotilus natans].
- Author
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Eprintsev AT, Vu TL, Selivanova NV, and Khasan Khamad A
- Subjects
- Bacterial Proteins chemistry, Bacterial Proteins metabolism, Chlorides chemistry, Chlorides metabolism, Chromatography, Gel, Citric Acid Cycle physiology, Electrophoresis, Polyacrylamide Gel, Enzyme Activation, Hydrogen-Ion Concentration, Isoenzymes chemistry, Isoenzymes isolation & purification, Isoenzymes metabolism, Kinetics, Protein Conformation, Protein Multimerization, Protein Subunits chemistry, Protein Subunits metabolism, Sphaerotilus chemistry, Succinate Dehydrogenase chemistry, Succinate Dehydrogenase metabolism, Bacterial Proteins isolation & purification, Protein Subunits isolation & purification, Sphaerotilus enzymology, Succinate Dehydrogenase isolation & purification
- Abstract
Enzymatic preparations of two isoforms of succinate dehydrogenase (SDG) with specific activity of 22.00 E/mg of protein were obtained from the colorless sulfur bacterium Sphaerotilus natans D-507 cultured organotrophically. Both SDG forms were shown to be heteromers with subunit molecular masses of 70.8, 35.0, 31.8, and 16.2 kDa. The K(m) values for the first and the second forms of SDG were evaluated as 0.615 and 0.531 mM, respectively, with an optimal pH value of 7.2. It was found that the Cl- ion has an activating effect on the SDG activity that can be explained by the specific chemical modification of the enzyme molecule. The results suggest that the isolated enzyme forms are included in different multienzyme complexes, which provide the functioning of the tricarboxylic acid cycle, and SDG preparations can be used for the investigation of other enzyme systems or in vitro modeling of supramolecular cellular structures.
- Published
- 2012
36. Discovery of a second human molar and cranium fragment in the late Middle to Late Pleistocene cave of Ma U'Oi (Northern Vietnam).
- Author
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Demeter F, Bacon AM, Nguyen KT, Vu TL, Duringer P, Roussé S, Coppens Y, Matsumura H, Dodo Y, Nguyen MH, and Tomoko A
- Subjects
- Animals, Anthropology, Physical, Fossils, Humans, Vietnam, Hominidae anatomy & histology, Molar anatomy & histology, Skull anatomy & histology
- Abstract
In November 2002, during the second season of work by a Vietnamese-French-Japanese team, we discovered a human molar and a fragment of an occipital bone in the late Middle to Late Pleistocene cave of Ma U'Oi (Bacon et al., Geobios. 37 (2004) 305). The layer from which this material comes is the same as that in which a human lower molar was found in 2001. Both molars can be attributed to archaic Homo, and both exhibit archaic and modern traits.
- Published
- 2005
- Full Text
- View/download PDF
37. Hepatocyte hollow-fibre bioreactors: design, set-up, validation and applications.
- Author
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Planchamp C, Vu TL, Mayer JM, Reist M, and Testa B
- Subjects
- Animals, Cell Culture Techniques instrumentation, Cells, Cultured, Humans, Reproducibility of Results, Bioreactors, Biotechnology methods, Cell Culture Techniques methods, Hepatocytes cytology
- Abstract
Hepatocytes carry out many vital biological functions, such as synthetic and catabolic reactions, detoxification and excretion. Due to their ability to restore a tissue-like environment, hollow-fibre bioreactors (HFBs) show great potential among the different systems used to culture hepatocytes. Several designs of HFBs have been proposed in which hepatocytes or hepatocyte-derived cell lines can be cultured in suspensions or on a solid support. Currently the major use of hepatocyte HFBs is as bioartificial livers to sustain patients suffering from acute liver failure, but they can also be used to synthesize cell products and as cellular models for drug metabolism and transport studies. Here, we present an overview of the set-up of hepatocyte HFBs and aim to provide potential users with the basic knowledge necessary to develop their own system. First, general information on HFBs is given, including basic principles, transport phenomena, designs and cell culture conditions. The importance of the tests necessary to assess the performance of the HFBs, i.e. the viability and functionality of hepatocytes, is underlined. Special attention is paid to drug metabolism studies and to adequate analytical methods. Finally, the potential uses of hepatocyte HFBs are described.
- Published
- 2003
- Full Text
- View/download PDF
38. Fetal blood and tissue PO2 during maternal oxygen breathing.
- Author
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Towell ME, Johnson J, Smedstad K, Andrew M, and Vu TL
- Subjects
- Animals, Arteries, Electromyography, Female, Myometrium physiology, Partial Pressure, Pregnancy, Sheep, Fetal Blood metabolism, Oxygen blood, Respiration
- Abstract
The effect of 100% oxygen breathing on fetal blood and tissue PO2 was examined in chronically catheterised fetal sheep of 12 pregnant ewes. Blood PO2 was monitored with intravascular polarographic electrodes and tissue PO2 with galvanic electrodes implanted in various tissues. In non-acidotic healthy fetuses, oxygen breathing increased fetal PO2 by 30% within 3 min in arterial blood and within 5 min in tissues. Thereafter blood PO2 increased by a maximum of 40% at 9 min and tissue PO2 rose by a maximum of 52% at 12 min. Blood PO2 returned promptly to control values after 15 min of oxygen breathing but washout of oxygen from tissues was slower and tissue PO2 remained significantly higher in the post-oxygen versus the pre-oxygen period. Continuation of oxygen breathing for 30 min did not lead to any further increase in tissue PO2. Oxygen breathing did not prevent a decrease in fetal PO2 associated with spontaneous myoelectrical activity of the uterus. It is concluded that maternal oxygen breathing leads to a significant increase in both blood and tissue PO2 in the healthy fetus. The majority of the increase occurs within the first 3-4 min and no further increase in either blood or tissue PO2 is observed after 12 min.
- Published
- 1984
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