47 results on '"Vu CA"'
Search Results
2. Solid Phase Extraction of Cesium from Aqueous Solution Using Sol-Gel Encapsulated Cobalt Hexacyanoferrate
- Author
-
Vu Ca, Diep and Cox, James A.
- Published
- 2004
- Full Text
- View/download PDF
3. Geological Structures and Age of the Magmatic Rocks Related to Primary Gold in Vietnam
- Author
-
Le Tuan, Nguyen Hoang, and Vu Cam
- Subjects
Geology ,QE1-996.5 - Abstract
The research on gold in Vietnam has been interesting to many authors. So far, studies on Geology-Minerals on the territory of Vietnam have determined that there are hundreds of gold mineralization. The structures related to primary gold in Vietnam have identified as Truong Son Fold Belt/ East Indochina Block and Sino-Vietnam composit Terran corresponding to Mountain belt internal contents early Paleozoic and Areas with high metamorphism. The magma formations associated with the mineralization zone contain gold mainly in the P3-T1 period, primary gold in Vietnam is closely related to the folding structure. Primary gold in Vietnam is an ore type of quartz-polymetallic sulfide-gold (silver) and quartz-sulfur-gold. Our research results have contributed to orienting the search for primary gold in Vietnam.
- Published
- 2023
- Full Text
- View/download PDF
4. Nghiên cứu đặc tính hóa lý và ảnh hưởng của pH đến khả năng hấp phụ ammonium, nitrite và nitrate của than sinh học từ xơ dừa
- Author
-
Võ Thị Minh Thảo, Nguyễn Thị Cành, Nguyễn Lữ Nguyệt Hằng, Vũ Cao Lan Anh, Nguyễn Minh Khánh, Nguyễn Ngọc Phi, Trần Tuấn Anh, Phạm Thị Ái Niệm, and Nguyễn Tấn Đức
- Subjects
điểm điện tích không ,hấp phụ ,khả năng giữ nước ,than sinh học ,xơ dừa ,Biotechnology ,TP248.13-248.65 - Abstract
Mục tiêu của nghiên cứu này là xác định các tính chất hóa lý và ảnh hưởng của pH đến khả năng hấp phụ ammonium, nitrite và nitrate của than sinh học từ xơ dừa từ đó hướng đến làm vật liệu lọc trong xử lý nước thải. Nghiên cứu sử dụng các phương pháp thường quy trong xác định hiệu suất tạo than, độ tro, khối lượng riêng, pH, EC và phân tích cấu trúc vật liệu bằng SEM, BET, FTIR và XRD. Đồng thời, xác định ảnh hưởng của pH đến khả năng hấp phụ các hợp chất nitrogen trong xơ dừa thông qua hiệu suất hấp phụ. Kết quả cho thấy than sinh học từ xơ dừa có độ giữ nước khá lớn 503.87 ± 36.44%, diện tích bề mặt riêng đạt 378.41 m2/g; trên bề mặt than có nhiều lỗ rỗng, độ xốp cao với kích thước lỗ rỗng hấp phụ và giải hấp phụ trung bình đạt 0.118nm và 0.121nm và có các nhóm chức O-H, C = O, -CH, C = C thuận lợi cho cơ chế hấp phụ hóa học. Than sinh học xơ dừa có pHPZC là 5.2 và có cấu trúc carbon vô định hình. Giá trị pH để hấp phụ tốt ammonium là 8 và nitrite, nitrate là 2 với hiệu suất hấp phụ lần lượt là 40%, 99.78% và 99.11% từ đó hướng đến tối ưu hóa quá trình loại bỏ các hợp chất nitrogen trong môi trường.
- Published
- 2023
- Full Text
- View/download PDF
5. Host-pathogen relationship in retreated tuberculosis with major rifampicin resistance–conferring mutations
- Author
-
Nguyen Thi Le Hang, Minako Hijikata, Shinji Maeda, Pham Huu Thuong, Hoang Van Huan, Nguyen Phuong Hoang, Do Bang Tam, Pham Thu Anh, Nguyen Thu Huyen, Vu Cao Cuong, Nobuyuki Kobayashi, Keiko Wakabayashi, Akiko Miyabayashi, Shintaro Seto, and Naoto Keicho
- Subjects
Mycobacterium tuberculosis ,recurrence ,rifampicin resistance ,rpoB variants ,whole genome sequencing ,blood transcriptomic signatures ,Microbiology ,QR1-502 - Abstract
IntroductionIt is assumed that host defense systems eliminating the pathogen and regulating tissue damage make a strong impact on the outcome of tuberculosis (TB) disease and that these processes are affected by rifampicin (RIF) resistance–conferring mutations of Mycobacterium tuberculosis (Mtb). However, the host responses to the pathogen harboring different mutations have not been studied comprehensively in clinical settings. We analyzed clinico-epidemiological factors and blood transcriptomic signatures associated with major rpoB mutations conferring RIF resistance in a cohort study.MethodsDemographic data were collected from 295 active pulmonary TB patients with treatment history in Hanoi, Vietnam. When recruited, drug resistance–conferring mutations and lineage-specific variations were identified using whole-genome sequencing of clinical Mtb isolates. Before starting retreatment, total RNA was extracted from the whole blood of HIV-negative patients infected with Mtb that carried either the rpoB H445Y or rpoB S450L mutation, and the total RNA was subjected to RNA sequencing after age-gender matching. The individual RNA expression levels in the blood sample set were also measured using real-time RT-PCR. Logistic and linear regression models were used to assess possible associations.ResultsIn our cohort, rpoB S450L and rpoB H445Y were major RIF resistance–conferring mutations [32/87 (36.8%) and 15/87 (17.2%), respectively]. H445Y was enriched in the ancient Beijing genotype and was associated with nonsynonymous mutations of Rv1830 that has been reported to regulate antibiotic resilience. H445Y was also more frequently observed in genetically clustered strains and in samples from patients who had received more than one TB treatment episode. According to the RNA sequencing, gene sets involved in the interferon-γ and-α pathways were downregulated in H445Y compared with S450L. The qRT-PCR analysis also confirmed the low expression levels of interferon-inducible genes, including BATF2 and SERPING1, in the H445Y group, particularly in patients with extensive lesions on chest X-ray.DiscussionOur study results showed that rpoB mutations as well as Mtb sublineage with additional genetic variants may have significant effects on host response. These findings strengthen the rationale for investigation of host-pathogen interactions to develop countermeasures against epidemics of drug-resistant TB.
- Published
- 2023
- Full Text
- View/download PDF
6. Optimization of the dispersion of gold and platinum nanoparticles on indium tin oxide for the electrocatalytic oxidation of cysteine and arsenite
- Author
-
James A. Cox, Laisheng Sun, and Diep Vu Ca
- Subjects
General Chemical Engineering ,Inorganic chemistry ,chemistry.chemical_element ,Nanoparticle ,Platinum nanoparticles ,Mole fraction ,Electrocatalyst ,Indium tin oxide ,chemistry.chemical_compound ,chemistry ,Triethoxysilane ,Electrochemistry ,Cyclic voltammetry ,Platinum - Abstract
Gold and platinum nanoparticles (NPs) were prepared by chemical reduction of the corresponding metal complex bound by ion-exchange to generation-4 poly(amidoamine) dendrimers (PAMAM). Arrays of the NPs on indium tin oxide (ITO) electrodes were formed by adsorbing a monolayer comprising a controlled ratio of NP-PAMAM to PAMAM on ITO that was modified with 3-aminopropyl triethoxysilane; subsequently, the organic components were thermally destroyed. Varying the above-defined ratio resulted in a commensurate change of the density of the NPs on the surface. Using an electrode modified in a solution with a mole fraction of Au-PAMAM (relative to total of Au-PAMAM and PAMAM) of 0.06, which gave NPs separated by 200 nm, the current for the catalytic oxidation of cysteine reached a value that did not increase when more nanoparticles were present. The analogous experiment on the oxidation of As III with PtNPs as the catalyst was optimized at a mole fraction of 0.2. Calculations assuming hemispherical diffusion suggested that the diffusion domains during cyclic voltammetry at 5 mV s −1 were less than the distance between the NPs.
- Published
- 2006
- Full Text
- View/download PDF
7. Electrocatalysis of the hydrogen evolution reaction by nanocomposites of poly(amidoamine)-encapsulated platinum nanoparticles and phosphotungstic acid
- Author
-
Diep Vu Ca, Laisheng Sun, and James A. Cox
- Subjects
Materials science ,Inorganic chemistry ,chemistry.chemical_element ,Poly(amidoamine) ,Condensed Matter Physics ,Platinum nanoparticles ,Electrocatalyst ,Indium tin oxide ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Monolayer ,Triethoxysilane ,Electrochemistry ,General Materials Science ,Phosphotungstic acid ,Electrical and Electronic Engineering ,Platinum - Abstract
Poly(amidoamine) dendrimer (Generation-4) encapsulated platinum nanoparticles (PtNP-PAMAM) were prepared and used to fabricate nanocomposites with Keggin-type phosphotungstic acid (PW12O403−) using a layer by layer electrostatic assembly technique. Indium tin oxide (ITO) electrodes, which were first modified with a monolayer of 3-aminopropyl triethoxysilane (3-APTES), were used as substrates for assembly of the PW12O403− monolayer. Nanocomposites were then fabricated by depositing PtNP-PAMAM on the monolayer of PW12O403−. The amount of PtNP-PAMAM deposited was controlled by using different concentrations of PtNP-PAMAM diluted in 0.1 M H2SO4 solution. The hydrogen evolution reaction (HER) was used to test electrocatalytic activities of these nanocomposite modified electrodes. Modification of ITO|3-APTES with PW12O403− |PtNP-PAMAM showed significantly higher electrocatalytic activities toward the HER than electrodes modified with either PW12O403− or PtNP-PAMAM alone. The electrocatalytic activities were found to depend on the composition of PtNP-PAMAM and PW12O403− on electrode surfaces, which was attributed to an interaction between these species. Heat treatment of ITO|3-APTES|PW12O403− |PtNP-PAMAM electrodes at 200 °C produced significantly higher electrocatalytic activities, which supported the suggestion of an interaction.
- Published
- 2005
- Full Text
- View/download PDF
8. The influence of the matrix structure on the oxidation of aniline in a silica sol–gel composite
- Author
-
Justyna Widera, Richard T. Taylor, Gilbert E. Pacey, H. Perfect, Diep Vu Ca, Anna M. Kijak, and James A. Cox
- Subjects
Materials science ,General Chemical Engineering ,Inorganic chemistry ,Microporous material ,Mesoporous silica ,Ormosil ,Tetraethyl orthosilicate ,chemistry.chemical_compound ,Aniline ,Chemical engineering ,chemistry ,Polyaniline ,Electrochemistry ,Mesoporous material ,Sol-gel - Abstract
Mesoporous and microporous silica matrices were formed on indium tin oxide electrodes for liquid-phase voltammetry and as monoliths for solid-state voltammetry of aniline. The pore structure, which was verified by scanning probe microscopy and by surface area measurement, was directed by either control of pH during sol–gel processing or by inclusion of a templating agent. Whether aniline was included as a dopant in the sol–gel or as a component of the contacting liquid, the pore size influenced the coupling of the product of its electrochemical oxidation. With microporous silica, the dominant products were dimers and related short-chain products whereas with mesoporous silica, polymerization was suggested. As a step toward the formation of polyaniline (PANI) that is covalently anchored to the sol–gel, the electrochemistry of aniline was investigated using composites prepared from sols comprising tetraethyl orthosilicate (TEOS), 3-aminophenyl-[3-triethoxylsilyl)-propyl] urea (ormosil), and aniline in various ratios. Combinatorial chemistry identified that the optimum combination of silica precursors in terms of obtaining PANI was a 1:12 mole ratio of ormosil:TEOS.
- Published
- 2005
- Full Text
- View/download PDF
9. Investor sentiment measurement based on technical analysis indicators affecting stock returns: Empirical evidence on VN100
- Author
-
Lai Cao Mai Phuong and Vu Cam Nhung
- Subjects
excess return ,principal component analysis ,psychological line index ,relative strength index ,technical indicator ,Finance ,HG1-9999 - Abstract
The purpose of this study is to examine whether investor sentiment as measured by technical analysis indicators has an impact on stock returns. The research period is from 2015 to mid-2020. 1-year government bond yields, financial data, transaction data of 57 companies in the VN100 basket, and VNIndex are analyzed. The investor sentiment variable is measured by each technical analysis indicator (Relative Strength Index – RSI, Psychological Line Index – PLI), and the general sentiment variable is established based on extracting the principal component from individual indicators. The paper uses two regression methods – Fama-MacBeth and Generalized Least Square (GLS) – for five different research models. The results show that sentiment plays an important role in stock returns in the Vietnamese stock market. Even controlling the factors such as cash flow per share, firm size, market risk premium, and stock price volatility in the studied models, the impact of sentiment is significant in both the model using individual technical indicators and the model using the general sentiment variable. Furthermore, investor sentiment has a stronger power to explain excess stock returns than their trading behavior. The implication from the results shows that the Vietnamese stock market is inefficient, in which psychology is a very important issue and participants need to pay due attention to this factor. AcknowledgmentThis study was funded by the Industrial University of Ho Chi Minh City (IUH), Vietnam (grant number: 21/1TCNH03).
- Published
- 2021
- Full Text
- View/download PDF
10. A parameterization scheme for the sensible heat exchange between the street canyon and the atmosphere using the relationship narrowness index and wind velocity
- Author
-
M.Abu Eusuf, Vu Ca Thanh, and Takashi Asaeda
- Subjects
Atmosphere ,Canyon ,geography ,Index (economics) ,geography.geographical_feature_category ,Meteorology ,Close relationship ,Environmental science ,Sensible heat ,Atmospheric sciences ,Wind speed ,Street canyon - Abstract
This paper investigates the behaviors of the sensible heat exchange between the top of the canyon and outside atmosphere using a numerical model together with available field measurement data. It was found that the heating characteristic of the urban canyon has close relationship with the narrowness index and outside wind velocity. The increase of the narrowness index and consequently, reduction of the sky-view factor leads to the reduction of sensible heat exchange between street canyon and outside atmosphere. The increase of outside wind velocity makes the sensible heat exchange between the street canyon and outside atmosphere larger, and consequently cooler the street canyon. A parameterization scheme was established which permits the evaluation of the sensible heat exchange between street canyon and outside atmosphere based on the narrowness index and outside wind velocity.
- Published
- 1994
- Full Text
- View/download PDF
11. Measurement platforms fabricated by layer-by-layer assembly of crown ether functionalized gold nanoclusters
- Author
-
Diep Vu Ca, Kevin W. Kittredge, and James A. Cox
- Subjects
chemistry.chemical_classification ,Materials science ,Layer by layer ,Supramolecular chemistry ,Nanotechnology ,Quartz crystal microbalance ,Condensed Matter Physics ,Nanoclusters ,chemistry.chemical_compound ,Ferrocene ,chemistry ,Colloidal gold ,Monolayer ,Electrochemistry ,General Materials Science ,Electrical and Electronic Engineering ,Crown ether - Abstract
Mixed-ligand monolayer-protected gold nanoclusters (MPCs) with crown ether (CE) and carboxylate functionalities were synthesized and used as components of layer-by-layer (LBL) electrostatic assemblies on gold and indium tin oxide (ITO) electrodes. The purpose of using MPCs was to provide a supramolecular anchor for a functionality, CEs, of interest to sensor and solid-phase extraction design; the carboxylate provided the charged sites needed for electrostatic assembly. With 15-crown-5 as the CE, the capture of 2.8×10-10 mol PbII cm-2 per monolayer of MPC was demonstrated by voltammetry and by electrochemical quartz crystal microbalance measurements. The diffusion of ferrocene through these LBL assemblies was investigated. The presence of MPCs and/or generation-4 poly(amidoamine) dendrimers allowed facile transport of ferrocene to the underlying electrode, presumably because these supramolecular assemblies provided a quasi-porous structure.
- Published
- 2004
- Full Text
- View/download PDF
12. Solid Phase Extraction of Cesium from Aqueous Solution Using Sol-Gel Encapsulated Cobalt Hexacyanoferrate
- Author
-
Diep Vu Ca and James A. Cox
- Subjects
Aqueous solution ,chemistry ,Dendrimer ,Inorganic chemistry ,Composite number ,chemistry.chemical_element ,Solid phase extraction ,Solubility ,Cobalt ,Analytical Chemistry ,Sol-gel ,Solid solution - Abstract
The synthesis and evaluation of silica sol-gels doped with cobalt hexacyanoferrate (CoHCF) for solid phase extraction of Cs+ from aqueous solution is described. The CoHCF is formed by first introducing K4Fe(CN)6 (HCF) into the sol-gel and subsequently contacting the porous solid to a solution containing Co2+. Generally, sols contain alcohol as a co-solvent, which limits the solubility of HCF. Inclusion of generation-4 polyamidoamine (G4-PAMAM) dendrimer in the sol-gel increases the level of HCF and, in turn, the CoHCF. The uptake capacity of this composite was 0.43±0.01 mmol Cs+ g−1. A second approach to increasing the level of HCF silica is to exclude alcohol from the sol and use ultrasound to obtain a homogeneous suspension; HCF concentrations up to 0.17 M in the sol were thereby achieved. After gelation and reaction with Co2+, the resulting composite had a capacity of 0.61±0.01 mmol Cs+ g−1. With 0.5 mM Cs+ as the sample, the presence of either 0.5–100 mM Na+ or 10 mM Ca2+ did not change that value at the 95% confidence level.
- Published
- 2004
- Full Text
- View/download PDF
13. SIMULATION OF HO CHI MINH CITY TEMPERATURE CHANGE ON THE URBAN MASTER PLAN TO 2020
- Author
-
Luong, Viet Van, primary and Vu, Ca Thanh, primary
- Published
- 2010
- Full Text
- View/download PDF
14. Whole genome sequencing, analyses of drug resistance-conferring mutations, and correlation with transmission of Mycobacterium tuberculosis carrying katG-S315T in Hanoi, Vietnam
- Author
-
Nguyen Thi Le Hang, Minako Hijikata, Shinji Maeda, Pham Huu Thuong, Jun Ohashi, Hoang Van Huan, Nguyen Phuong Hoang, Akiko Miyabayashi, Vu Cao Cuong, Shintaro Seto, Nguyen Van Hung, and Naoto Keicho
- Subjects
Medicine ,Science - Abstract
Abstract Drug-resistant tuberculosis (TB) is a serious global problem, and pathogen factors involved in the transmission of isoniazid (INH)-resistant TB have not been fully investigated. We performed whole genome sequencing of 332 clinical Mycobacterium tuberculosis (Mtb) isolates collected from patients newly diagnosed with smear-positive pulmonary TB in Hanoi, Vietnam. Using a bacterial genome-wide approach based on linear mixed models, we investigated the associations between 31-bp k-mers and clustered strains harboring katG-S315T, a major INH-resistance mutation in the present cohort and in the second panel previously published in South Africa. Five statistically significant genes, namely, PPE18/19, gid, emrB, Rv1588c, and pncA, were shared by the two panels. We further identified variants of the genes responsible for these k-mers, which are relevant to the spread of INH-resistant strains. Phylogenetic convergence test showed that variants relevant to PPE46/47-like chimeric genes were significantly associated with the same phenotype in Hanoi. The associations were further confirmed after adjustment for the confounders. These findings suggest that genomic variations of the pathogen facilitate the expansion of INH-resistance TB, at least in part, and our study provides a new insight into the mechanisms by which drug-resistant Mtb maintains fitness and spreads in Asia and Africa.
- Published
- 2019
- Full Text
- View/download PDF
15. Internal social capital banking and activities of commercial bank
- Author
-
Lai Cao Mai Phuong and Vu Cam Nhung
- Subjects
Accounting. Bookkeeping ,HF5601-5689 - Abstract
The study aims to explore the impact of internal social capital banking on the operations of commercial banks in Vietnam. The study is executed in two phases. Phase 1 uses the expert method to build scales and design survey questions. In phase two, scale test and structural equation model analysis (SEM) are performed with a sample of 243 questionnaires for directors and deputy directors of branches of 32 commercial banks in Ho Chi Minh City. It also analyzes the contribution of the structure of the relational network within the bank and the quality of the relational network. The research results show that internal banking social capital affects all three operations; namely mobilization, lending and service provision of the banks. Based on the research results, the study proposes an analytical framework to improve the quality of internal banking relationships.
- Published
- 2020
- Full Text
- View/download PDF
16. External social capital banking and activities of commercial bank
- Author
-
Vu Cam Nhung and Lai Cao Mai Phuong
- Subjects
Accounting. Bookkeeping ,HF5601-5689 - Abstract
This study conducted a survey on 243 branches of 32 commercial banks in Ho Chi Minh City in 2016 to explore and measure the composition of social capital affecting capital activities, using capital activities and service provision activities of commercial banks. The paper uses Exploratory Factor Analysis (EFA), CFA affirmation analysis and the Structural Equation Modeling (SEM). The results show that social capital directly affects all three activities of commercial banks. In addition, the study found that capital activity has a direct impact on using capital, activities of using capital directly affect the provision of services, and capital activities indirectly impact on service provision.
- Published
- 2020
- Full Text
- View/download PDF
17. A parameterization scheme for the sensible heat exchange between the street canyon and the atmosphere using the relationship narrowness index and wind velocity.
- Author
-
Eusuf, M.Abu, primary, Thanh, Vu Ca, additional, and Asaeda, Takashi, additional
- Published
- 1994
- Full Text
- View/download PDF
18. A regularization method for time-fractional linear inverse diffusion problems
- Author
-
Nguyen Huy Tuan, Mokhtar Kirane, Vu Cam Hoan Luu, and Bandar Bin-Mohsin
- Subjects
Regularization method ,inverse advection-dispersion problem ,Caputo fractional derivatives ,convergence estimate ,Mathematics ,QA1-939 - Abstract
In this article, we consider an inverse problem for a time-fractional diffusion equation with a linear source in a one-dimensional semi-infinite domain. Such a problem is obtained from the classical diffusion equation by replacing the first-order time derivative by the Caputo fractional derivative. We show that the problem is ill-posed, then apply a regularization method to solve it based on the solution in the frequency domain. Convergence estimates are presented under the a priori bound assumptions for the exact solution. We also provide a numerical example to illustrate our results.
- Published
- 2016
19. Nghiên cứu sự biến động sinh khối phiêu sinh thực vật và hàm lượng ôxy hòa tan để quản lý đàn cá trên kênh Nhiêu Lộc - Thị Nghè, Thành phố Hồ Chí Minh
- Author
-
Vũ Cẩm Lương and Hồ Đại
- Subjects
Đàn cá ,kênh Nhiêu Lộc Thị Nghè ,ôxy hòa tan ,phiêu sinh thực vật ,Science - Abstract
Nghiên cứu được thực hiện trong suốt chu kỳ một năm, với sáu đợt thu mẫu vào các tháng 1, 3, 5, 7, 9 và 11 năm 2015, nhằm khảo sát biến động sinh khối phiêu sinh thực vật (PSTV) và hàm lượng ôxy hòa tan (DO) trên kênh Nhiêu Lộc – Thị Nghè (NL-TN) theo không gian, thời gian và thủy triều, qua đó đề xuất giải pháp quản lý đàn cá trên kênh. Nghiên cứu đã phân vùng kênh NL-TN theo ba đoạn, đầu kênh, giữa kênh và cuối kênh với chín trạm thu mẫu. Mẫu được thu đại diện cho các thời điểm thủy triều cao nhất và thấp nhất trong tháng. Kết quả cho thấy sinh khối PSTV đạt cao nhất ở đoạn cuối kênh (5,2-6,1 gDW/m3) và thấp nhất ở đoạn đầu kênh (4,4-4,9 gDW/m3), tuy nhiên không có mối tương quan giữa sinh khối PSTV cao và DO xuống thấp vào sáng sớm theo không gian. Xét theo khía cạnh thời gian, sinh khối PSTV đạt cao nhất vào tháng 7 (6,9 gDW/m3) và thấp nhất vào tháng 9 (3,5 gDW/m3), tuy nhiên không có mối tương quan giữa sinh khối PSTV và DO theo thời gian. Như vậy việc quan trắc sinh khối PSTV với tần suất 2 tháng/lần là chưa có hiệu quả trong dự báo tương quan biến động của chỉ số này với sự thiếu hụt DO nhằm mục đích quản lý đàn cá. Xét theo biến động thủy triều, các mức nước lớn và nước ròng ảnh hưởng có ý nghĩa lên sự khác biệt sinh khối trung bình năm của PSTV. Xét riêng khía cạnh DO, mức DO xuống thấp nhất vào thời điểm sáng sớm của tháng 5 khi nước ròng, trùng hợp với hiện tượng cá chết nhiều trên kênh vào đầu mùa mưa, đặt ra yêu cầu cần quan trắc và quản lý DO thường xuyên vào các thời điểm dễ xảy ra nguy cơ thiếu hụt DO để quản lý đàn cá.
- Published
- 2018
- Full Text
- View/download PDF
20. Đánh giá hiệu quả của hoạt động ương và kinh doanh cá trê lai giống (Clarias macrocephalus x C. Gariepinus) ở tỉnh Tiền Giang
- Author
-
Huỳnh Thị Ngọc Huyền, Nguyễn Như Trí, and Vũ Cẩm Lương
- Subjects
Cá trê lai ,kinh doanh ,Tiền Giang ,ương ,Science - Abstract
Nghiên cứu đã tiến hành điều tra 110 hộ ương và 38 cơ sở kinh doanh cá trê lai giống trên địa bàn tỉnh Tiền Giang từ tháng 02/2017 đến tháng 10/2017 nhằm đánh giá hiệu quả của các hoạt động trên. Kết quả khảo sát hoạt động ương cá trê lai giống cho thấy, nhóm hộ có diện tích trung bình ao ương 1.000-2.000 m2/ao (nhóm I) và 2.001-3.000 m2/ao (nhóm II) có năng suất và lợi nhuận cao hơn nhóm diện tích trung bình ao ương 3.001-6.000 m2/ao (nhóm III) với khác biệt có ý nghĩa về mặt thống kê (p
- Published
- 2018
- Full Text
- View/download PDF
21. Dynamics of immune parameters during the treatment of active tuberculosis showing negative interferon gamma response at the time of diagnosis
- Author
-
Ikumi Matsushita, Nguyen Thi Le Hang, Le Thi Hong, Do Bang Tam, Luu Thi Lien, Pham Huu Thuong, Vu Cao Cuong, Minako Hijikata, Nobuyuki Kobayashi, Shinsaku Sakurada, Kazue Higuchi, Nobuyuki Harada, and Naoto Keicho
- Subjects
Interferon gamma release assay ,False-negative result ,Sensitivity ,Interleukin 1 receptor antagonist ,Interleukin 2 ,Interferon gamma-induced protein 10 ,Infectious and parasitic diseases ,RC109-216 - Abstract
Objectives: In the performance of interferon gamma release assays (IGRA) for the diagnosis of tuberculosis (TB) infection, false-negative results are a major obstacle. In active TB patients, treatment-dependent changes of the negative test results remain unknown. Methods: The treatment course of 19 smear-positive/culture-confirmed TB patients who had IGRA-negative results by QuantiFERON-TB in-tube (QFT-IT) method at the time of diagnosis (month 0) in a previous study, were monitored in the present study. Blood was further collected at months 2 and 7, and the concentrations of 27 immune molecules were measured in the plasma supernatants remaining after performing the IGRA, using a suspension array system. Results: After initiating treatment, eight of the 19 QFT-IT-negative patients showed positive conversion, whereas the remaining 11 (58%) did not; the interferon gamma (IFN-γ) response was restored to levels higher than 1 IU/ml in only three of the eight patients with positive conversion. Plasma concentrations of interleukin 1 receptor antagonist, interleukin 2, and interferon gamma-induced protein 10 remained low after Mycobacterium tuberculosis-specific antigen stimulation at months 2 and 7 in the continuously QFT-IT-negative group, whereas the parameters were elevated only in the transiently QFT-IT-negative group. Conclusions: It was demonstrated that a majority of active TB patients showing negative IGRA results did not regain sufficient levels of immune responsiveness despite successful treatment.
- Published
- 2015
- Full Text
- View/download PDF
22. A truncation regularization method for a time fractional diffusion equation with an in-homogeneous source
- Author
-
Vu Cam Hoan Luu, Duy Binh Ho, and Bao Ngoc Tran
- Subjects
Ill-posed problem ,time fractional diffusion equation ,regularization ,regularized truncation method ,Information technology ,T58.5-58.64 - Abstract
In the present paper, we consider a time-fractional inverse diffusion problem with an in-homogeneous source, where data is given at x = 1 and the solution is required in the interval 0 < x < 1. This problem is ill-posed, i.e. the solution (if it exists) does not depend continuously on the data. We propose a regularization method to solve it based on the solution given by the Fourier method.
- Published
- 2018
- Full Text
- View/download PDF
23. Primary drug-resistant tuberculosis in Hanoi, Viet Nam: present status and risk factors.
- Author
-
Nguyen Thi Le Hang, Shinji Maeda, Luu Thi Lien, Pham Huu Thuong, Nguyen Van Hung, Tran Bich Thuy, Akiko Nanri, Tetsuya Mizoue, Nguyen Phuong Hoang, Vu Cao Cuong, Khieu Thi Thuy Ngoc, Shinsaku Sakurada, Hiroyoshi Endo, and Naoto Keicho
- Subjects
Medicine ,Science - Abstract
INTRODUCTION: Resistance of Mycobacterium tuberculosis (MTB) to anti-tuberculosis (TB) drugs presents a serious challenge to TB control worldwide. We investigated the status of drug resistance, including multidrug-resistant (MDR) TB, and possible risk factors among newly diagnosed TB patients in Hanoi, the capital of Viet Nam. METHODS: Clinical and epidemiological information was collected from 506 newly diagnosed patients with sputum smear- and culture-positive TB, and 489 (96.6%) MTB isolates were subjected to conventional drug susceptibility testing, spoligotyping, and 15-locus variable numbers of tandem repeats typing. Adjusted odds ratios (aORs) were calculated to analyze the risk factors for primary drug resistance. RESULTS: Of 489 isolates, 298 (60.9%) were sensitive to all drugs tested. Resistance to isoniazid, rifampicin, streptomycin, ethambutol, and MDR accounted for 28.2%, 4.9%, 28.2%, 2.9%, and 4.5%, respectively. Of 24 isolates with rifampicin resistance, 22 (91.7%) were MDR and also resistant to streptomycin, except one case. Factors associated with isoniazid resistance included living in old urban areas, presence of the Beijing genotype, and clustered strains [aOR = 2.23, 95% confidence interval (CI) 1.15-4.35; 1.91, 1.18-3.10; and 1.69, 1.06-2.69, respectively). The Beijing genotype was also associated with streptomycin resistance (aOR = 2.10, 95% CI 1.29-3.40). Human immunodeficiency virus (HIV) coinfection was associated with rifampicin resistance and MDR (aOR = 5.42, 95% CI 2.07-14.14; 6.23, 2.34-16.58, respectively). CONCLUSION: Isoniazid and streptomycin resistance was observed in more than a quarter of TB patients without treatment history in Hanoi. Transmission of isoniazid-resistant TB among younger people should be carefully monitored in urban areas, where Beijing strains and HIV coinfection are prevalent. Choosing an optimal treatment regimen on the basis of the results of drug susceptibility tests and monitoring of treatment adherence would minimize further development of drug resistance strains.
- Published
- 2013
- Full Text
- View/download PDF
24. Prevalence and risk factors for tuberculosis infection among hospital workers in Hanoi, Viet Nam.
- Author
-
Luu Thi Lien, Nguyen Thi Le Hang, Nobuyuki Kobayashi, Hideki Yanai, Emiko Toyota, Shinsaku Sakurada, Pham Huu Thuong, Vu Cao Cuong, Akiko Nanri, Tetsuya Mizoue, Ikumi Matsushita, Nobuyuki Harada, Kazue Higuchi, Le Anh Tuan, and Naoto Keicho
- Subjects
Medicine ,Science - Abstract
BACKGROUND: Transmission of tuberculosis (TB) to health care workers (HCWs) is a global issue. Although effective infection control measures are expected to reduce nosocomial TB, HCWs' infection has not been assessed enough in TB high burden countries. We conducted a cross-sectional study to determine the prevalence of TB infection and its risk factors among HCWs in Hanoi, Viet Nam. METHODOLOGY/PRINCIPAL FINDINGS: A total of 300 HCWs including all staff members in a municipal TB referral hospital received an interferon-gamma release assay (IGRA), QuantiFERON-TB Gold In-Tube(TM), followed by one- and two-step tuberculin skin test (TST) and a questionnaire-based interview. Agreement between the tests was evaluated by kappa statistics. Risk factors for TB infection were analyzed using a logistic regression model. Among the participants aged from 20 to 58 years (median = 40), prevalence of TB infection estimated by IGRA, one- and two-step TST was 47.3%, 61.1% and 66.3% respectively. Although the levels of overall agreement between IGRA and TST were moderate, the degree of agreement was low in the group with BCG history (kappa = 0.29). Working in TB hospital was associated with twofold increase in odds of TB infection estimated by IGRA. Increased age, low educational level and the high body mass index also demonstrated high odds ratios of IGRA positivity. CONCLUSIONS/SIGNIFICANCE: Prevalence of TB infection estimated by either IGRA or TST is high among HCWs in the hospital environment for TB care in Viet Nam and an infection control program should be reinforced. In communities with heterogeneous history of BCG vaccination, IGRA seems to estimate TB infection more accurately than any other criteria using TST.
- Published
- 2009
- Full Text
- View/download PDF
25. Duration of antibiotic therapy for multidrug resistant Pseudomonas aeruginosa pneumonia: is shorter truly better?
- Author
-
Truong CN, Chin-Beckford N, Vega A, DeRonde K, Simon J, Abbo LM, Rosa R, and Vu CA
- Subjects
- Humans, Male, Female, Retrospective Studies, Aged, Middle Aged, Pneumonia, Ventilator-Associated drug therapy, Pneumonia, Ventilator-Associated microbiology, Pneumonia, Ventilator-Associated mortality, Treatment Outcome, Pneumonia, Bacterial drug therapy, Pneumonia, Bacterial microbiology, Pneumonia, Bacterial mortality, Duration of Therapy, Pseudomonas aeruginosa drug effects, Anti-Bacterial Agents therapeutic use, Anti-Bacterial Agents administration & dosage, Drug Resistance, Multiple, Bacterial, Pseudomonas Infections drug therapy, Pseudomonas Infections microbiology, Pseudomonas Infections mortality
- Abstract
Background: The 2016 IDSA guideline recommends a treatment duration of at least 7 days for hospital-acquired (HAP)/ventilator-associated pneumonia (VAP). The limited literature has demonstrated higher rates of recurrence for non-glucose fermenting gram-negative bacilli with short course therapy, raising the concern of optimal treatment duration for these pathogens. Therefore, we aimed to compare the outcomes for patients receiving shorter therapy treatment (≤ 8 days) versus longer regimen (> 8 days) for the treatment of multidrug resistant (MDR) Pseudomonas pneumonia., Methods: A single-center, retrospective cohort study was conducted to evaluate adult patients receiving an antimicrobial regimen with activity against MDR Pseudomonas aeruginosa in respiratory culture between 2017 and 2020 for a minimum of 6 consecutive days. Exclusion criteria were inmates, those with polymicrobial pneumonia, community-acquired pneumonia, and infections requiring prolonged antibiotic therapy., Results: Of 427 patients with MDR P. aeruginosa respiratory isolates, 85 patients were included. Baseline characteristics were similar among groups with a median age of 65.5 years and median APACHE 2 score of 20. Roughly 75% had ventilator-associated pneumonia. Compared to those who received ≤ 8 days of therapy, no difference was seen for clinical success in patients treated for more than 8 days (80% vs. 65.5%, p = 0.16). The number of 30-day and 90-day in-hospital mortality, 30-days relapse, and other secondary outcomes did not significantly differ among the treatment groups., Conclusions: Prolonging treatment duration beyond 8 days did not improve patient outcomes for MDR P. aeruginosa HAP/VAP., (© 2024. The Author(s).)
- Published
- 2024
- Full Text
- View/download PDF
26. Intermittent lysis on a single paper-based device to extract exosomal nucleic acid biomarkers from biological samples for downstream analysis.
- Author
-
Vu VT, Vu CA, Huang CJ, Cheng CM, Pan SC, and Chen WY
- Subjects
- Humans, Biomarkers, Tumor blood, Point-of-Care Testing, Exosomes chemistry, Paper, Tetraspanin 30 metabolism, MicroRNAs analysis, MicroRNAs blood
- Abstract
As the role of exosomes in physiological and pathological processes has been properly perceived, harvesting them and their internal components is critical for subsequent applications. This study is a debut of intermittent lysis, which has been integrated into a simple and easy-to-operate procedure on a single paper-based device to extract exosomal nucleic acid biomarkers for downstream analysis. Exosomes from biological samples were captured by anti-CD63-modified papers before being intermittently lysed by high-temperature, short-time treatment with double-distilled water to release their internal components. Exosomal nucleic acids were finally adsorbed by sol-gel silica for downstream analysis. Empirical trials not only revealed that sporadically dropping 95 °C ddH
2 O onto the anti-CD63-modified papers every 5 min for 6 times optimized the exosomal nucleic acids extracted by the anti-CD63 paper but also verified that the whole deployed procedure is applicable for point-of-care testing (POCT) in low-resource areas and for both in vitro (culture media) and in vivo (plasma and chronic lesion) samples. Importantly, downstream analysis of exosomal miR-21 extracted by the paper-based procedure integrated with this novel technique discovered that the content of exosomal miR-21 in chronic lesions related to their stages and the levels of exosomal carcinoembryonic antigen originated from colorectal cancer cells correlated to their exosomal miR-21., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)- Published
- 2024
- Full Text
- View/download PDF
27. Comparing solution-gate and bottom-gate nanowire field-effect transistors on pH sensing with different salt concentrations and surface modifications.
- Author
-
Hu WP, Yang YQ, Lee CH, Vu CA, and Chen WY
- Abstract
Field-effect transistors (FETs) have been developed as pH sensors by using various device structures, fabrication technologies, and sensing film materials. Different transistor structures, like extended-gate (EG) FETs, floating-gate FET sensors, and dual-gate (DG) FETs, can enhance the sensor performance. In this article, we report the effects of using solution-gate and bottom-gate FET configurations on pH sensing and investigate the influence of different ionic concentrations of buffers in the measured signals. The surface charge of hafnium dioxide (HfO
2 ) affected by the buffer pH, with/without the modification of polyethylene glycol (PEG) terminated with hydroxyl groups, and the location of applied gate voltage are vital factors to the sensor performance in pH sensing. Based on the results, the solution-gate FET exhibits good pH sensitivity even in the high ionic strength solutions of bis-tris propane (BTP), and these values of pH sensitivity are close to the Nernst limit (59.2 mV/pH). In general, silane-PEG-OH modification can reduce the deviations of measured signals in pH sensing. The performance of bottom-gate FET is inferior in the BTP buffers with high ionic solutions but suitable to be operated in low ionic concentrations, such as 0.1, 1, and 10 mM BTP buffers. The size of the ions was also studied and discussed. The solution-gate FET demonstrates excellent performance under high ionic strengths, meaning a more significant potential for detecting biological molecules under physiological conditions., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)- Published
- 2024
- Full Text
- View/download PDF
28. Nocardia brasiliensis Pyomyositis in an Immunocompetent Patient Following Gardening Activity.
- Author
-
Rehman A, Olayiwola A, Vu CA, Bhatt P, Joseph JA, and Ayoade F
- Subjects
- Humans, Male, Middle Aged, Ceftriaxone therapeutic use, Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization, Drainage, Moxifloxacin therapeutic use, Moxifloxacin administration & dosage, Linezolid therapeutic use, Nocardia Infections diagnosis, Nocardia Infections drug therapy, Nocardia isolation & purification, Anti-Bacterial Agents therapeutic use, Pyomyositis drug therapy, Pyomyositis diagnosis, Pyomyositis microbiology, Gardening, Immunocompetence
- Abstract
Nocardia pyomyositis in immunocompetent patients is a rare occurrence. The diagnosis may be missed or delayed with the risk of progressive infection and suboptimal or inappropriate treatment. We present the case of a 48-year-old immunocompetent firefighter diagnosed with pyomyositis caused by Nocardia brasiliensis acquired by direct skin inoculation from gardening activity. The patient developed a painful swelling on his right forearm that rapidly progressed proximally and deeper into the underlying muscle layer. Ultrasound imaging of his right forearm showed a 7-mm subcutaneous fluid collection with surrounding edema. Microbiologic analysis of the draining pus was confirmed to be N brasiliensis by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight (MALDI-TOF) Mass Spectrometry. After incision and drainage deep to the muscle layer to evacuate the abscess and a few ineffective antibiotic options, the patient was treated with intravenous ceftriaxone and oral linezolid for 6 weeks. He was then de-escalated to oral moxifloxacin for an additional 4 months to complete a total antibiotic treatment duration of 6 months. The wound healed satisfactorily and was completely closed by the fourth month of antibiotic therapy. Six months after discontinuation of antibiotics, the patient continued to do well with complete resolution of the infection. In this article, we discussed the risk factors for Nocardia in immunocompetent settings, the occupational risks for Nocardia in our index patient, and the challenges encountered with diagnosis and treatment. Nocardia should be included in the differential diagnosis of cutaneous infections, particularly if there is no improvement of "cellulitis" with traditional antimicrobial regimens and the infection extends into the deeper muscle tissues., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest for the research, authorship, and/or publication of this article.
- Published
- 2024
- Full Text
- View/download PDF
29. Paper/PMMA hybrid device with a microvalve-controlled design for exosome isolation and analysis.
- Author
-
Hu WP, Lai YF, Vu CA, Tsao CW, Pan SC, Cheng CM, and Chen WY
- Subjects
- Polymethyl Methacrylate, Exosomes chemistry, MicroRNAs analysis
- Abstract
This study proposes a paper/PMMA hybrid device designed to isolate exosomes and extract exosomal miRNA, followed by quantitative analysis. It aims to provide simplified and convenient sample preparation for potential point-of-care testing (POCT) processes. In contrast to previous work conducted by our research team, which focused on isolating exosomes and exosomal nucleic acids, this study introduces a novel approach by integrating paper and a PMMA mold with a microvalve controlled design. This innovative method enables the entire process to be performed on paper. The pressure on the paper could be adjusted by turning the screw upon the valve to change the pore size and permeability of the paper, which achieved the effect of controlling the flow rate of fluids. The paper was designed to have an immunoaffinity area for capturing exosomes and a sol-gel silica coating area for extracting miRNA. The paper-based ELISA (p-ELISA) exhibited a limit of detection and a limit of quantitation of 6 × 10
7 and 5.4 × 108 particles/mL, respectively, for exosome measurement. The reverse transcription quantitative polymerase chain reaction (RT-qPCR) revealed that the Ct (threshold cycle) value for quantifying the miR-21 in the miRNAs extracted by the proposed paper/PMMA hybrid device was comparable to the Ct value of the commercial extraction kit. The developed paper/PMMA hybrid device with a microvalve-controlled design should be incorporated into the POCT system to extract exosomal miRNAs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)- Published
- 2023
- Full Text
- View/download PDF
30. Paper-Based Exosomal MicroRNA-21 Detection for Wound Monitoring: A Proof of Concept and Clinical Validation Trial Study.
- Author
-
Pan SC, Lai CH, Vu VT, Vu CA, Huang CJ, Cheng CM, and Chen WY
- Subjects
- Humans, Wound Healing genetics, Research Design, MicroRNAs genetics, MicroRNAs metabolism, Exosomes genetics, Exosomes metabolism
- Abstract
Emerging evidence has shown that microRNAs play pivotal roles in wound healing. MicroRNA-21 (miR-21) was previously found to upregulate in order to fulfill an anti-inflammation role for wounds. Exosomal miRNAs have been identified and explored as essential markers for diagnostic medicine. However, the role of exosomal miR-21 in wounds has yet to be well studied. In order to facilitate the early management of poorly healing wounds, we developed an easy-to-use, rapid, paper-based microfluidic-exosomal miR-21 extraction device to determine wound prognosis in a timely manner. We isolated and then quantitatively examined exosomal miR-21 in wound fluids from normal tissues and acute and chronic wounds. Eight improving wounds displayed lower levels of exosomal miR-21 expression after wound debridement. However, four instances of increased exosomal miR-21 expression levels were notably associated with patients with poor healing wounds despite aggressive wound debridement, indicating a predictive role of tissue exosomal miR-21 for wound outcome. Paper-based nucleic acid extraction device provides a rapid and user-friendly approach for evaluating exosomal miR-21 in wound fluids as a means of monitoring wounds. Our data suggest that tissue exosomal miR-21 is a reliable marker for determining current wound status.
- Published
- 2023
- Full Text
- View/download PDF
31. Successful Outcome after Treatment with Cidofovir, Vaccinia, and Extended Course of Tecovirimat in a Newly-Diagnosed HIV Patient with Severe Mpox: A Case Report.
- Author
-
Martinez AE, Frattaroli P, Vu CA, Paniagua L, Mintz J, Bravo-Gonzalez A, Zamudio P, Barco A, Rampersad A, Lichtenberger P, and Gonzales-Zamora JA
- Abstract
Purpose: To report a case of severe mpox in a newly diagnosed HIV patient concerning for Immune Reconstitution Inflammatory Syndrome (IRIS) and/or tecovirimat resistance and to describe the management approach in the setting of refractory disease., Case: 49-year-old man presented with 2 weeks of perianal lesions. He tested positive for mpox PCR in the emergency room and was discharged home with quarantine instructions. Three weeks later, the patient returned with disseminated firm, nodular lesions in the face, neck, scalp, mouth, chest, back, legs, arms, and rectum, with worsening pain and purulent drainage from the rectum. The patient reported being on 3 days of tecovirimat treatment, which was prescribed by the Florida department of health (DOH). During this admission, he was found to be HIV positive. A pelvic CT scan revealed a 2.5 cm perirectal abscess. Treatment with tecovirimat was continued for 14 days, along with an empiric course of antibiotics for treatment of possible superimposed bacterial infection upon discharge. He was seen in the outpatient clinic and initiated antiretroviral therapy (ART) with TAF/emtricitabine/bictegravir. Two weeks after starting ART, the patient was readmitted for worsening mpox rash and rectal pain. Urine PCR also returned positive for chlamydia, for which the patient was prescribed doxycycline. He was discharged on a second course of tecovirimat and antibiotic therapy. Ten days later, the patient was readmitted for the second time due to worsening symptoms and blockage of the nasal airway from progressing lesions. At this point, there were concerns for tecovirimat resistance, and after discussion with CDC, tecovirimat was reinitiated for the third time, with the addition of Cidofovir and Vaccinia, and showed an improvement in his symptoms. He received three doses of cidofovir and two doses of Vaccinia, and the patient was then discharged to complete 30 days of tecovirimat. Outpatient follow-up showed favorable outcomes and near resolution., Conclusion: We reported a challenging case of worsening mpox after Tecovirimat treatment in the setting of new HIV and ART initiation concerning IRIS vs. Tecovirimat resistance. Clinicians should consider the risk of IRIS and weigh the pros and cons of initiating or delaying ART. In patients not responding to first-line treatment with tecovirimat, resistance testing should be performed, and alternative options should be considered. Future research is needed to establish guidance on the role of Cidofovir and Vaccinia immune globulin and the continuation of tecovirimat for refractory mpox.
- Published
- 2023
- Full Text
- View/download PDF
32. Ultrasensitive Detection of Interleukin 6 by Using Silicon Nanowire Field-Effect Transistors.
- Author
-
Hu WP, Wu YM, Vu CA, and Chen WY
- Subjects
- Humans, Silicon, Transistors, Electronic, Interleukin-6, Silicon Dioxide, Antibodies, Nanowires, Biosensing Techniques methods, COVID-19 diagnosis
- Abstract
Interleukin 6 (IL-6) has been regarded as a biomarker that can be applied as a predictor for the severity of COVID-19-infected patients. The IL-6 level also correlates well with respiratory dysfunction and mortality risk. In this work, three silanization approaches and two types of biorecognition elements were used on the silicon nanowire field-effect transistors (SiNW-FETs) to investigate and compare the sensing performance on the detection of IL-6. Experimental data revealed that the mixed-SAMs-modified silica surface could have superior surface morphology to APTES-modified and APS-modified silica surfaces. According to the data on detecting various concentrations of IL-6, the detection range of the aptamer-functionalized SiNW-FET was broader than that of the antibody-functionalized SiNW-FET. In addition, the lowest concentration of valid detection for the aptamer-functionalized SiNW-FET was 2.1 pg/mL, two orders of magnitude lower than the antibody-functionalized SiNW-FET. The detection range of the aptamer-functionalized SiNW-FET covered the concentration of IL-6, which could be used to predict fatal outcomes of COVID-19. The detection results in the buffer showed that the anti-IL-6 aptamer could produce better detection results on the SiNW-FETs, indicating its great opportunity in applications for sensing clinical samples.
- Published
- 2023
- Full Text
- View/download PDF
33. Challenges and opportunities in stewardship among solid organ transplant recipients with Candida auris bloodstream infections.
- Author
-
Vu CA, Jimenez A, Anjan S, and Abbo LM
- Subjects
- Antifungal Agents therapeutic use, Candida, Candida auris, Candidiasis, Invasive, Echinocandins therapeutic use, Humans, Micafungin, Retrospective Studies, Transplant Recipients, Fungemia drug therapy, Organ Transplantation adverse effects
- Abstract
Background: Candida auris is an emerging nosocomial pathogen worldwide. However, there has been little published on the management of C. auris in solid organ transplant recipients., Methods: A single-center, retrospective cohort study was conducted to evaluate C. auris bloodstream infections in solid organ transplant recipients between January 2020 and December 2021. Patient-related and outcomes data were extracted from electronic medical records., Results: Of the 42 patients identified with C. auris bloodstream infections, five were in solid organ transplant recipients (1 heart, 3 liver, and 1 combined liver-kidney). The median time to fungemia from hospital admission was 43 days, and the median time to fungemia from transplant was 18 days. All patients received micafungin as initial treatment, at a median of 6 hours from pathogen detection. Four patients achieved blood clearance, two patients had persistent fungemia, and two patients developed secondary complications from hematogenous spread. One patient died, resulting in a mortality rate of 20%., Conclusions: Solid organ transplant recipients are at high risk for developing C. auris bloodstream infections. In order to prevent graft loss and mortality, best practices for the management of C.auris should include rapid screening, diagnosis, and treatment. While echinocandins are considered first-line, antifungal selection should be based on susceptibilities and site of infection. Data to support routine use of combination therapy are lacking, however there may be a role for refractory cases. Prevention efforts against C. auris infection are especially important given the lack of effective decolonization strategies. For transplant recipients, hospitals should seek opportunities to restore patients' gut microbiome by curtailing unnecessary hospital procedures and inappropriate antimicrobial use. Further research and national guidelines are needed to better direct stewardship in this field., (© 2022 Wiley Periodicals LLC.)
- Published
- 2022
- Full Text
- View/download PDF
34. Prevalence of and incentives for board certification among hospital pharmacy departments in California.
- Author
-
Yeung SL, Vu CA, Wang M, Lou M, and Ng TMH
- Subjects
- California, Certification, Cross-Sectional Studies, Humans, Motivation, Pharmacists, Prevalence, Prospective Studies, Pharmacy, Pharmacy Service, Hospital
- Abstract
Purpose: Board of Pharmacy Specialties (BPS) certification is endorsed to distinguish pharmacists for advanced practice areas, yet perceived value to stakeholders remains poorly described. This study characterized how board certification is integrated in hospital pharmacy departments across California., Methods: A prospective, cross-sectional study was conducted in which a survey was administered to all hospital pharmacy directors in California between November 2019 and March 2020. Licensed institutions and corresponding pharmacy directors were identified from the California State Board of Pharmacy. The survey queried for institution and pharmacy director characteristics and if/how board certification was integrated. Multivariable logistic models identified predictors of institutions with at least 25% full-time board certified pharmacists and those that reward board certification., Results: Surveys were completed by 29% of institutions. Most of these institutions were urban (81%) and nonteaching (57%), with fewer than 325 hospital beds (71%), and with fewer than 50 full-time pharmacist positions (86%). The majority reported that less than 25% of their pharmacists were board certified. Currently, 47% consider board certification during hiring and 38% reward board certified employees. Predictors of institutions with 25% or more board certified pharmacists included being a teaching institution (odds ratio [OR], 2.96; 95% confidence interval [CI], 1.24-7.06), having 325 or more beds (OR, 7.17; 95% CI, 2.86-17.97), and having a pharmacy director who was previously or currently board certified (OR, 3.69; 95% CI, 1.46-9.35). Hospitals with 100 or more pharmacist positions predicted institutions that reward board certification (OR, 16.69; 95% CI, 1.78-156.86)., Conclusion: Board certification was an employment preference for almost half of the hospital survey respondents in California. Institutions more likely to reward board certified pharmacists are larger, urban, and teaching hospitals and have pharmacy directors who have been board certified., (© American Society of Health-System Pharmacists 2021. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)
- Published
- 2022
- Full Text
- View/download PDF
35. Paper-Based Devices for Capturing Exosomes and Exosomal Nucleic Acids From Biological Samples.
- Author
-
Lai CH, Lee CL, Vu CA, Vu VT, Tsai YH, Chen WY, and Cheng CM
- Abstract
Exosomes, nanovesicles derived from cells, contain a variety of biomolecules that can be considered biomarkers for disease diagnosis, including microRNAs (miRNAs). Given knowledge and demand, inexpensive, robust, and easy-to-use tools that are compatible with downstream nucleic acid detection should be developed to replace traditional methodologies for point-of-care testing (POCT) applications. This study deploys a paper-based extraction kit for exosome and exosomal miRNA analytical system with some quantifying methods to serve as an easy sample preparation for a possible POCT process. Exosomes concentrated from HCT116 cell cultures were arrested on paper-based immunoaffinity devices, which were produced by immobilizing anti-CD63 antibodies on Whatman filter paper, before being subjected to paper-based silica devices for nucleic acids to be trapped by silica nanoparticles adsorbed onto Whatman filter paper. Concentrations of captured exosomes were quantified by enzyme-linked immunosorbent assay (ELISA), demonstrating that paper-based immunoaffinity devices succeeded in capturing and determining exosome levels from cells cultured in both neutral and acidic microenvironments, whereas microRNA 21 (miR-21), a biomarker for various types of cancers and among the nucleic acids absorbed onto the silica devices, was determined by reverse transcription quantitative polymerase chain reaction (RT-qPCR) to prove that paper-based silica devices were capable of trapping exosomal nucleic acids. The developed paper-based kit and the devised procedure was successfully exploited to isolate exosomes and exosomal nucleic acids from different biological samples (platelet-poor plasma and lesion fluid) as clinical applications., 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 © 2022 Lai, Lee, Vu, Vu, Tsai, Chen and Cheng.)
- Published
- 2022
- Full Text
- View/download PDF
36. Optimizing surface modification of silicon nanowire field-effect transistors by polyethylene glycol for MicroRNA detection.
- Author
-
Vu CA, Lai HY, Chang CY, Chan HW, and Chen WY
- Subjects
- Polyethylene Glycols, Silicon, Transistors, Electronic, Biosensing Techniques, MicroRNAs genetics, Nanowires
- Abstract
MicroRNA (miRNA) sensing plays an essential role in the diagnosis of several diseases, especially cancers, for appropriate intervention and treatment. However, quantifying miRNA demands highly sensitive and selective assays which can distinguish analogous sequences with low abundance in bio-samples and determine wide range of concentrations. In this report, we present a novel technique satisfying all those requirements by modifying silicon nanowire field-effect transistors (SiNWFETs) with 2-component mixed self-assembled monolayers (mSAMs) of polyethylene glycol (PEG) at different ratios (silane-PEG-NH
2 :silane-PEG-OH = 1:1, 1:3, and 1:5) and glutaraldehyde to immobilize DNA probes for miRNA-21 detection, a biomarker in several types of cancers. Empirical results reveal that all the fabricated PEG-SiNWFET DNA biosensors could quantify miRNA-21 within 1 fM - 10 pM. Especially, the ones modified with silane-PEG-NH2 :silane-PEG-OH = 1:3 exhibited an outstanding performance to recognize miRNA-21 at an ultra-low concentration of 10 aM in the dynamic range up to 6 orders of magnitude (10 aM - 10 pM). This approach is more convenient, analytical competitive, and cost-effective in comparison with currently used methods for nucleic acid testing because of label- and amplification-free characteristics. It is therefore not only feasible for miRNA detection by SiNWFET-based biosensors but also potential for clinical applications of disease diagnosis with oligonucleotide biomarkers., (Copyright © 2021 Elsevier B.V. All rights reserved.)- Published
- 2022
- Full Text
- View/download PDF
37. Phosphate-Methylated Oligonucleotides as a Novel Primer for PCR and RT-PCR.
- Author
-
Chang YH, Wu MW, Chen YJ, Vu CA, Hong CY, and Chen WY
- Subjects
- DNA genetics, Oligonucleotides genetics, Phosphates, Reverse Transcriptase Polymerase Chain Reaction, Polymerase Chain Reaction
- Abstract
This chapter introduces neutralized DNA (nDNA) as a novel design for the primers of PCR and RT-PCR by methylating phosphate groups of some oligonucleotides in their structures. It starts with an introduction of the nDNA which possesses an electrically chimeric neutral backbone as well as the proposed standards in designing nDNA as a novel primer for PCR and RT-PCR , concluded from various experimental results presented afterward. The primary content comprises empirical data from PCR to compare nDNA and unmodified DNA as primers in terms of ability to distinguish and amplify mismatch templates, activities of polymerase enzymes, melting temperature of double-stranded sequences, and the trials and discussions on various modified positions of the nDNA primers. In summary, nDNA exhibited outstanding performance as a primer for PCR and RT-PCR , compared to unmodified DNA, and is expected to be expanded in diverse applications which require enhanced specificity., (© 2022. Springer Science+Business Media, LLC, part of Springer Nature.)
- Published
- 2022
- Full Text
- View/download PDF
38. Isavuconazole for the prophylaxis and treatment of invasive fungal disease: A single-center experience.
- Author
-
Vu CA, Rana MM, Jacobs SE, and Saunders-Hao P
- Subjects
- Antifungal Agents therapeutic use, Humans, Retrospective Studies, Invasive Fungal Infections drug therapy, Nitriles therapeutic use, Pyridines therapeutic use, Triazoles therapeutic use
- Abstract
Background: Invasive fungal disease (IFD) is a serious complication among the immunocompromised population. Isavuconazole is a newer broad-spectrum antifungal agent with promising efficacy and safety. However, there remains limited data to favor its use over current first-line agents., Objectives: We aimed to evaluate isavuconazole use and describe rates of associated breakthrough invasive fungal disease (bIFD)., Methods: A single-center, retrospective study was conducted to evaluate patients receiving isavuconazole for prophylaxis or treatment of IFD between July 1, 2017 and December 31, 2018. Patient-related and outcomes data were extracted from electronic medical records. Descriptive statistics were used to analyze our findings., Results: A total of 54 patients received 61 isavuconazole courses. Isavuconazole was most commonly prescribed for primary prophylaxis in the acute myeloid leukemia (AML) and allogeneic hematopoietic stem cell transplant (HSCT) population along with treatment for possible invasive fungal disease. The primary reasons for choosing isavuconazole included QTc shortening effects, decreased risk of acute kidney injury, broader spectrum of activity, and concern for breakthrough invasive fungal disease on a different prophylactic agent. We found a breakthrough rate of 8.5% for patients and 7.8% for courses., Conclusions: Isavuconazole appears to be a promising alternative for prophylaxis and treatment of invasive fungal disease. We observed similar bIFD rates and improved tolerability when compared to historical data for posaconazole and voriconazole., (© 2020 Wiley Periodicals LLC.)
- Published
- 2021
- Full Text
- View/download PDF
39. Combination of Aptamer Amplifier and Antigen-Binding Fragment Probe as a Novel Strategy to Improve Detection Limit of Silicon Nanowire Field-Effect Transistor Immunosensors.
- Author
-
Vu CA, Pan PH, Yang YS, Chan HW, Kumada Y, and Chen WY
- Subjects
- Animals, Immunoassay, Limit of Detection, Proteins analysis, Rabbits, Silicon, Biosensing Techniques, Nanowires
- Abstract
Detecting proteins at low concentrations in high-ionic-strength conditions by silicon nanowire field-effect transistors (SiNWFETs) is severely hindered due to the weakened signal, primarily caused by screening effects. In this study, aptamer as a signal amplifier, which has already been reported by our group, is integrated into SiNWFET immunosensors employing antigen-binding fragments (Fab) as the receptors to improve its detection limit for the first time. The Fab-SiNWFET immunosensors were developed by immobilizing Fab onto Si surfaces modified with either 3-aminopropyltriethoxysilane (APTES) and glutaraldehyde (GA) (Fab/APTES-SiNWFETs), or mixed self-assembled monolayers (mSAMs) of polyethylene glycol (PEG) and GA (Fab/PEG-SiNWFETs), to detect the rabbit IgG at different concentrations in a high-ionic-strength environment (150 mM Bis-Tris Propane) followed by incubation with R18, an aptamer which can specifically target rabbit IgG, for signal enhancement. Empirical results revealed that the signal produced by the sensors with Fab probes was greatly enhanced compared to the ones with whole antibody (Wab) after detecting similar concentrations of rabbit IgG. The Fab/PEG-SiNWFET immunosensors exhibited an especially improved limit of detection to determine the IgG level down to 1 pg/mL, which has not been achieved by the Wab/PEG-SiNWFET immunosensors.
- Published
- 2021
- Full Text
- View/download PDF
40. Supratherapeutic Posaconazole Concentration in a Pediatric Transplant Patient With Confirmed Rhizopus Infection.
- Author
-
Vu CA, Riollano-Cruz M, and Kowalsky SR
- Abstract
There are a limited number of studies that guide dosing of posaconazole delayed-release (DR) tablets for the pediatric population. Current FDA-approved doses are only recommended for patients 13 years and older. For younger patients, providers are faced with the challenge of recommending posaconazole doses extrapolated from adult studies or choosing an alternative agent. We report on a case of a 10-year-old patient who experienced a supratherapeutic trough serum concentration and transaminitis after receiving the extrapolated adult dosage of posaconazole DR tablets (300 mg twice daily for the first day, followed by 300 mg daily) for 7 days. In the end, the patient required a smaller dose of 200 mg daily to achieve the desired trough target concentration for the treatment of a Rhizopus neck infection. Our findings highlight the need for additional studies to determine the optimal dosing of posaconazole DR tablets for children., Competing Interests: Disclosures. The authors declare no conflicts or financial interest in any product or service mentioned in the manuscript, including grants, equipment, medications, employment, gifts, and honoraria. The authors had full access to all patient information in this report and take responsibility for the integrity and accuracy of the report., (Copyright. Pediatric Pharmacy Association. All rights reserved. For permissions, email: mhelms@pediatricpharmacy.org 2021.)
- Published
- 2021
- Full Text
- View/download PDF
41. Effects of Tocilizumab in COVID-19 patients: a cohort study.
- Author
-
Vu CA, DeRonde KJ, Vega AD, Maxam M, Holt G, Natori Y, Zamora JG, Salazar V, Boatwright R, Morris SR, de Lima Corvino D, Betances AF, Colucci L, Keegan J, Lopez A, Rezk AH, Rodriguez Y, Moraru GM, Doblecki S, De La Zerda DJ, and Abbo LM
- Subjects
- Adult, Aged, Aged, 80 and over, Antibodies, Monoclonal, Humanized pharmacology, COVID-19 complications, Cohort Studies, Female, Hospitalization, Humans, Male, Middle Aged, Respiratory Insufficiency virology, Retrospective Studies, SARS-CoV-2, Treatment Outcome, Antibodies, Monoclonal, Humanized therapeutic use, Receptors, Interleukin-6 antagonists & inhibitors, Respiratory Insufficiency drug therapy, COVID-19 Drug Treatment
- Abstract
Background: Due to the lack of proven therapies, we evaluated the effects of early administration of tocilizumab for COVID-19. By inhibition of the IL-6 receptor, tocilizumab may help to mitigate the hyperinflammatory response associated with progressive respiratory failure from SARS-CoV-2., Methods: A retrospective, observational study was conducted on hospitalized adults who received intravenous tocilizumab for COVID-19 between March 23, 2020 and April 10, 2020., Results: Most patients were male (66.7%), Hispanic (63.3%) or Black (23.3%), with a median age of 54 years. Tocilizumab was administered at a median of 8 days (range 1-21) after initial symptoms and 2 days (range 0-12) after hospital admission. Within 30 days from receiving tocilizumab, 36 patients (60.0%) demonstrated clinical improvement, 9 (15.0%) died, 33 (55.0%) were discharged alive, and 18 (30.0%) remained hospitalized. Successful extubation occurred in 13 out of 29 patients (44.8%). Infectious complications occurred in 16 patients (26.7%) at a median of 10.5 days. After tocilizumab was administered, there was a slight increase in PaO
2 /FiO2 and an initial reduction in CRP, but this effect was not sustained beyond day 10., Conclusions: Majority of patients demonstrated clinical improvement and were successfully discharged alive from the hospital after receiving tocilizumab. We observed a rebound effect with CRP, which may suggest the need for higher or subsequent doses to adequately manage cytokine storm. Based on our findings, we believe that tocilizumab may have a role in the early treatment of COVID-19, however larger randomized controlled studies are needed to confirm this.- Published
- 2020
- Full Text
- View/download PDF
42. Development and Implementation of a COVID-19 Disease Response Protocol at a Large Academic Medical Center.
- Author
-
Maxam M, DeRonde KJ, Vega AD, Skiada D, Vu CA, Salazar V, Boatwright R, Cano-Casillas E, Goodnow V, Sposato KA, Paige PG, Zambrana D, Steigman DS, Memon AM, and Abbo LM
- Subjects
- COVID-19 diagnosis, COVID-19 therapy, Humans, Inservice Training, SARS-CoV-2, Academic Medical Centers organization & administration, COVID-19 epidemiology, Clinical Protocols, Infection Control organization & administration
- Abstract
In response to the rapid spread of novel coronavirus disease 2019 (COVID-19), health-care systems should establish procedures for early recognition and management of suspected or confirmed cases. We describe the various steps taken for the development, implementation, and dissemination of the interdisciplinary COVID-19 protocol at Jackson Health System (JHS), a complex tertiary academic health system in Miami, Florida. Recognizing the dynamic nature of COVID-19, the protocol addresses the potential investigational treatment options and considerations for special populations. The protocol also includes infection prevention and control measures and routine care for suspected or proven COVID-19 patients.
- Published
- 2020
- Full Text
- View/download PDF
43. Development of a Standardized Data Collection Tool for Evaluation and Management of Coronavirus Disease 2019.
- Author
-
Morris SR, Natori Y, Salguero D, Mantero A, Ma R, de Lima Corvino DF, Fernandez A, Lazo A, Vu CA, Bjork L, Serota D, Quevedo J, Vega A, Maxam M, DeRonde K, Barreiro P, Raccamarich P, Alvarez MR, Skiada D, Balan S, Ramanathan M, Holt G, Gonzales-Zamora J, Baracco GJ, Doblecki-Lewis S, Abbo LM, Lichtenberger PN, and Alcaide ML
- Abstract
Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 ) is responsible for coronavirus disease 2019 (COVID-19), a disease that had not been previously described and for which clinicians need to rapidly adapt their daily practice. The novelty of SARS-CoV-2 produced significant gaps in harmonization of definitions, data collection, and outcome reporting to identify patients who would benefit from potential interventions., Methods: We describe a multicenter collaboration to develop a comprehensive data collection tool for the evaluation and management of COVID-19 in hospitalized patients. The proposed tool was developed by a multidisciplinary working group of infectious disease physicians, intensivists, and infectious diseases/antimicrobial stewardship pharmacists. The working group regularly reviewed literature to select important patient characteristics, diagnostics, and outcomes for inclusion. The data collection tool consisted of spreadsheets developed to collect data from the electronic medical record and track the clinical course after treatments., Results: Data collection focused on demographics and exposure epidemiology, prior medical history and medications, signs and symptoms, diagnostic test results, interventions, clinical outcomes, and complications. During the pilot validation phase, there was <10% missing data for most domains and components. Team members noted improved efficiency and decision making by using the tool during interdisciplinary rounds., Conclusions: We present the development of a COVID-19 data collection tool and propose its use to effectively assemble harmonized data of hospitalized individuals with COVID-19. This tool can be used by clinicians, researchers, and quality improvement healthcare teams. It has the potential to facilitate interdisciplinary rounds, provide comparisons across different hospitalized populations, and adapt to emerging challenges posed by the pandemic., (© The Author(s) 2020. Published by Oxford University Press on behalf of Infectious Diseases Society of America.)
- Published
- 2020
- Full Text
- View/download PDF
44. Predicting Future Prospects of Aptamers in Field-Effect Transistor Biosensors.
- Author
-
Vu CA and Chen WY
- Subjects
- Aptamers, Nucleotide metabolism, Biosensing Techniques methods
- Abstract
Aptamers, in sensing technology, are famous for their role as receptors in versatile applications due to their high specificity and selectivity to a wide range of targets including proteins, small molecules, oligonucleotides, metal ions, viruses, and cells. The outburst of field-effect transistors provides a label-free detection and ultra-sensitive technique with significantly improved results in terms of detection of substances. However, their combination in this field is challenged by several factors. Recent advances in the discovery of aptamers and studies of Field-Effect Transistor (FET) aptasensors overcome these limitations and potentially expand the dominance of aptamers in the biosensor market.
- Published
- 2020
- Full Text
- View/download PDF
45. Field-Effect Transistor Biosensors for Biomedical Applications: Recent Advances and Future Prospects.
- Author
-
Vu CA and Chen WY
- Subjects
- Antibodies chemistry, Aptamers, Nucleotide chemistry, Equipment Design, Humans, Molecular Probes chemistry, Biosensing Techniques instrumentation, Biosensing Techniques methods, Nanostructures chemistry, Transistors, Electronic
- Abstract
During recent years, field-effect transistor biosensors (Bio-FET) for biomedical applications have experienced a robust development with evolutions in FET characteristics as well as modification of bio-receptor structures. This review initially provides contemplation on this progress by briefly summarizing remarkable studies on two aforementioned aspects. The former includes fabricating unprecedented nanostructures and employing novel materials for FET transducers whereas the latter primarily synthesizes compact molecules as bio-probes (antibody fragments and aptamers). Afterwards, a future perspective on research of FET-biosensors is also predicted depending on current situations as well as its great demand in clinical trials of disease diagnosis. From these points of view, FET-biosensors with infinite advantages are expected to continuously advance as one of the most promising tools for biomedical applications., Competing Interests: The authors declare no conflict of interest.
- Published
- 2019
- Full Text
- View/download PDF
46. Signal Enhancement of Silicon Nanowire Field-Effect Transistor Immunosensors by RNA Aptamer.
- Author
-
Vu CA, Hu WP, Yang YS, Chan HW, and Chen WY
- Abstract
Silicon nanowire field-effect transistors (SiNW-FETs) have been demonstrated as a highly sensitive platform for label-free detection of a variety of biological and chemical entities. However, detecting signal from immunoassays by nano-FETs is severely hindered by the distribution of different charged groups of targeted entities, their binding orientation, and distances to the surface of the FET. Aptamers have been widely applied as a recognition element for plentiful biosensors because of small molecular sizes and moderate to high specific binding affinity with different types of molecules. In this study, we propose an effective approach to enhance the electrical responses of both direct (6×-histidine) and sandwich (amyloid β 1-42) immunoassays in SiNW-FETs with R18, a highly negative charged RNA aptamer against rabbit immunoglobulin G (IgG). Empirical results presented that the immunosensors targeted with R18 expressed a significantly stabilized and amplified signal compared to the ones without this aptamer. The research outcome provides applicability of the highly negative charged aptamer as a bioamplifier for immunoassays by FETs., Competing Interests: The authors declare no competing financial interest.
- Published
- 2019
- Full Text
- View/download PDF
47. [Protein shifts and the immunoglobulin and immune complex content of the blood serum or tropical malaria patients in the Socialist Republic of Vietnam].
- Author
-
Vu CA
- Subjects
- Acute Disease, Humans, Plasmodium falciparum, Vietnam, Antigen-Antibody Complex analysis, Blood Proteins analysis, Immunoglobulins analysis, Malaria immunology
- Published
- 1983
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.