Publications by authors named "Nguyen Q Hien"

For the first time, phytochemical constituents of the leaves of were investigated. One rare new 2,28-bidesmosidic lupane-type saponin, named heptaellipside A (), along with four other lupane-type analogs () were purified by combining differently chromatographic methods. All of the separated compounds () were communicated for the first time from .

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Sulfur is one of the inorganic elements used by plants to develop and produce phytoalexin to resist certain diseases. This study reported a method for preparing a material for plant disease resistance. Sulfur nanoparticles (SNPs) stabilized in the chitosan-Cu2+ (CS-Cu2+) complex were synthesized by hydrolysis of Na2S2O3 in an acidic medium.

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In this study, the gamma ray-induced Maillard reaction method was carried out for chitosan (CTS) and glucosamine (GA) to improve the water solubility and antibacterial activity. The mixture solution of CTS and GA was exposed to gamma rays at a dose of 25 kGy and freeze-dried to obtain a Maillard reaction product (MRP) powder. The physicochemical and biological properties of the CTS-GA MRP powder were investigated.

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Chitosan (CS) is only soluble in weak acid medium, thereby limiting its wide utilisation in the field of biomedicine, food, and agriculture. In this report, we present a method for preparing water-soluble CS oligosaccharides (COSs) at high concentration (∼10%, w/v) via the oxidative hydrolysis of CS powder with molecular weight (Mw) ∼90,000 g/mol) in 2% HO solution at ambient temperature by a two-step process, namely, the heterogeneous hydrolysis step and homogeneous hydrolysis step. The resultant COSs were characterised by gel permeation chromatography (GPC), fourier transforms infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-Vis), proton nuclear magnetic resonance spectroscopy (H NMR) and X-ray diffraction (XRD) spectroscopy.

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In this work, we present the results of the ortho-positronium (o-Ps) annihilation lifetimes and nitrogen adsorption measurements for different porous materials and an approach for describing the annihilation of o-Ps in a pore, which results in a surface-volume formula (SVF) for calculating the pore-related o-Ps lifetime. This proposed formula gives the relationship between the o-Ps annihilation rate and the effective pore radius, bulk composition, and pore structure, including pore geometry and topology. The pore-related o-Ps lifetimes of different materials calculated by the SVF are consistent with experimental results for both micro- and mesopores (and macropores) with different geometries and topologies.

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Searching for thiosemicarbazone derivatives with the potential to inhibit acetylcholinesterase for the treatment of Alzheimer's disease (AD) is an important current goal. The QSAR, QSAR, and QSAR models were constructed using binary fingerprints and physicochemical (PC) descriptors of 129 thiosemicarbazone compounds screened from a database of 3791 derivatives. The and values for the QSAR, QSAR, and QSAR models are greater than 0.

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This work presents the preparation of bioactive glasses 70SiO-(26 - )CaO-4PO-AgO (with = 0, 1, 3, 10 mol%) by a modified sol-gel method with reduced synthesis time based on hydrothermal reaction in a medium without acid or base catalysts. The synthetic materials were characterized by several physical-chemical techniques such as TG-DSC, XRD, SEM, TEM, and N adsorption/desorption measurement. The analysis data confirmed that the glass sample not containing Ag has a completely amorphous structure, while glass samples containing Ag exhibited a pure phase of metallic nano-silver in the glass amorphous phase.

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Unlabelled: Cardiac papillary fibroelastoma (CPF) is a benign primary cardiac neoplasm, commonly found in men and above 40 years old. The clinical presentation of CPF ranges from asymptomatic to embolism-related complications such as stroke, myocardial ischemia, infarction, or ventricular fibrillation. Acute coronary syndrome is a rare complication of CPF, which was reported only in a few cases in medical literature.

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Cu nanoparticles are a potential material for creating novel alternative antimicrobial products due to their unique antibacterial/antifungal properties, stability, dispersion, low cost and abundance as well as being economical and ecofriendly. In this work, carboxymethyl cellulose coated core/shell SiO@Cu nanoparticles (NPs) were synthesized by a simple and effective chemical reduction process. The initial SiO NPs, which were prepared from rice husk ash, were coated by a copper ultrathin film using hydrazine and carboxymethyl cellulose (CMC) as reducing agent and stable agent, respectively.

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From the Vietnamese plant (Lecomte) Danser, one new diarylpropanoid, named macrotricolorin A () together with three diarylheptanoids including bisdemethoxycurcumin (), demethoxycurcumin () and curcumin (), were isolated. Their structures were elucidated by intensive analyses of their IR, UV, HR-ESI-MS and NMR (1 D & 2 D) spectra. It is the first time that diarylalkanoids have been reported from the genus Compound exhibited anti-inflammatory activity against the nitric oxide (NO) production in lipopolysaccharide (LPS)-induced RAW264.

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A hospital-based, case-control study was conducted to investigate the association between lifestyle patterns and risk of colorectal cancer (CRC) in the north of Vietnam. Demographic factors employed for the models were age, sex, marital status, occupation, education, income, smoking status, alcohol consumption, vegetable consumption, tea, coffee consumption, and physical activity (PA). Individuals of both groups (n = 154 for the control group and n = 136 for the CRC group) were interviewed using a questionnaire by trained interviewers.

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Functional hybrid materials were successfully synthesized from low-cost waste products, such as oligochitosan (OCS) obtained from chitosan (one of the main components in crab shells) and nanosilica (nSiO₂) obtained from rice husk, in a 1:1 ratio (/), and their dispersion in the presence of carboxymethyl cellulose at pH 7 was stable for over one month without aggregation. The molecular weights, chemical structures, morphologies, and crystallinities of the obtained materials were characterized by GPC, FTIR, TEM, and XRD, respectively. The antifungal effects of OCS, nSiO₂, and the OCS/nSiO hybrid materials were investigated via a disk-diffusion method.

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Oligochitosan (COS) and oligo-β-glucan (βOG) were prepared by gamma Co-60 irradiation of chitosan/H O and β-glucan/H O solutions. The striped catfish (Pangasianodon hypophthalmus) was fed diets containing 0-200 mg COS, βOG, and a mixture of COS/βOG per kg feed for 45 days, and then challenged with Edwardsiella ictaluri bacterium. The effects of supplemented COS, βOG, and a mixture of COS/βOG on immune stimulation and growth performance in striped catfish were investigated.

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Background: Tuberculous meningitis is often lethal. Early antituberculosis treatment and adjunctive treatment with glucocorticoids improve survival, but nearly one third of patients with the condition still die. We hypothesized that intensified antituberculosis treatment would enhance the killing of intracerebral Mycobacterium tuberculosis organisms and decrease the rate of death among patients.

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Colloidal solutions of silver nanoparticles (AgNPs) were synthesized by gamma Co-60 irradiation using different stabilizers, namely polyvinyl pyrrolidone (PVP), polyvinyl alcohol (PVA), alginate, and sericin. The particle size measured from TEM images was 4.3, 6.

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Silver nanoparticles (AgNPs) with diameter about 12 nm were immobilized on the surface of cotton fabrics by γ-irradiation of fabrics in the AgNO3 chitosan solution. Effects of absorbed dose, concentration of AgNO3 solution on immobilization of the AgNPs on fabrics were investigated. The optimal dose was selected to be 13.

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Gold nanoparticles (AuNPs) with diameter from 4 to 10nm, capping by hyaluronan (HA) were synthesized using a γ-irradiation method. The maximum absorption wavelengths at 517-525 nm of colloidal AuNPs/HA solutions were measured by UV-vis spectroscopy. The size and size distribution of AuNPs were determined from TEM images.

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Degraded alginate compounds with molecular weights of 7-26, 40-77, or 11-26 kDa were obtained by γ irradiation, hydrogen peroxide (5% H(2)O(2)) treatment, or a combination treatment involving ionizing radiation and H(2)O(2), respectively. The 14 kDa oligoalginate, prepared by the combined method, promoted the growth of mustard greens and lettuce at an optimal concentration of 75 mg/L. The growth promotion effects of the oligoalginate prepared by γ irradiation in the presence of H(2)O(2) were statistically equivalent to those of the oligoalginate prepared by γ irradiation only.

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Chitosan from squid pens with deacetylation degree (DD) of 70% and average molecular weight (M) 90.5×10 in dilute lactic acid solution containing HO (1%) was effectively degraded by irradiation with gamma Co radiation (1.33kGy/h) at doses in the range 4-16kGy.

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Background: The optimal time to initiate antiretroviral therapy (ART) in human immunodeficiency virus (HIV)-associated tuberculous meningitis is unknown.

Methods: We conducted a randomized, double-blind, placebo-controlled trial of immediate versus deferred ART in patients with HIV-associated tuberculous meningitis to determine whether immediate ART reduced the risk of death. Antiretroviral drugs (zidovudine, lamivudine, and efavirenz) were started either at study entry or 2 months after randomization.

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The microscopic observation drug susceptibility assay (MODS) is a novel and promising test for the early diagnosis of tuberculosis (TB). We evaluated the MODS assay for the early diagnosis of TB in HIV-positive patients presenting to Pham Ngoc Thach Hospital for Tuberculosis and Lung Diseases in southern Vietnam. A total of 738 consecutive sputum samples collected from 307 HIV-positive individuals suspected of TB were tested by smear, MODS, and the mycobacteria growth indicator tube method (MGIT).

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Background: Tuberculous meningitis (TBM) caused by Mycobacterium tuberculosis resistant to 1 or more antituberculosis drugs is an increasingly common clinical problem, although the impact on outcome is uncertain.

Methods: We performed a prospective study of 180 Vietnamese adults admitted consecutively for TBM. M.

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Background: Tuberculous meningitis kills or disables more than half of those affected with the disease. Previous studies have been too small to determine whether adjunctive treatment with corticosteroids can reduce the risk of disability or death among adults with tuberculous meningitis, and the effect of coinfection with the human immunodeficiency virus (HIV) is unclear.

Methods: We performed a randomized, double-blind, placebo-controlled trial in Vietnam in patients over 14 years of age who had tuberculous meningitis, with or without HIV infection, to determine whether adjunctive treatment with dexamethasone reduced the risk of death or severe disability after nine months of follow-up.

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We investigated the clinical manifestations and course of all probable severe acute respiratory syndrome (SARS) patients in the Vietnam outbreak. Probable SARS cases were defined by using the revised World Health Organization criteria. We systematically reviewed medical records and undertook descriptive statistical analyses.

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The severe acute respiratory syndrome (SARS) outbreak in Vietnam was amplified by nosocomial spread within hospital A, but no transmission was reported in hospital B, the second of two designated SARS hospitals. Our study documents lack of SARS-associated coronavirus transmission to hospital B workers, despite variable infection control measures and the use of personal protective equipment.

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