Pandatonkinosides A and B: two new phenolic glycosides from the roots of Pandanus tonkinensis and their nitric oxide production inhibitory activities.

Two new phenolic glycosides, 4-(3-hydroxypropyl)-2,6-dimethoxyphenol ß-D-apiofuranosyl-(1→6)-ß-D-glucopyranoside (1), trans-cinnamyl alcohol 9-O-(6'-O-ß-D-apiofuranosyl)-ß-D-glucopyranoside (2), together with nine known phenolic glycosides (3-11) were isolated from the roots of Pandanus tonkinensis. Their structures were determined by extensive analysis of HRESIMS and NMR spectral data, as well as by comparison of their spectral data (including CD spectra) with those reported in the literature. Compounds 1-4 and 6-11 inhibited NO production in LPS-activated RAW264.7 cells with IC50 values in the range from 0.80 ± 0.06 µM to 43.38 ± 3.92 µM, whereas compound 5 was inactive. The NO production inhibitory activities of compounds 1, 4, 8, and 10 with IC50 values of 10.16 ± 1.05, 0.80 ± 0.06, 1.10 ± 0.13, and 2.79 ± 0.21 µM, respectively, are as potent as that of the positive control of NG-monomethyl-L-arginine acetate (L-NMMA) with an IC50 value of 9.80 ± 0.78 µM.

Enhanced biomineralization and protein adsorption capacity of 3D chitosan/hydroxyapatite biomimetic scaffolds applied for bone-tissue engineering.

This work presents the enhanced biomineralization and protein adsorption capacity of 3D chitosan/hydroxyapatite (CS/HAp) biomimetic scaffolds synthesized from natural sources applied for bone-tissue engineering (BTE). The scaffolds were prepared by the freeze-drying method, then characterized by X-ray diffraction, scanning electron microscopy, liquid substitution, swelling behavior, and mechanical strength. Fourier transform infrared spectroscopy was also conducted to investigate the interaction between chitosan (CS) and hydroxyapatite (HAp). The biodegradation, biomineralization and protein adsorption capabilities of the scaffolds were evaluated through tests in vitro. Results showed that the 3D CS/HAp scaffolds exhibited highly porous structures with an average pore size of 265 µm, and mean porosity of 75.01%, respectively; the tensile strength of the scaffolds was 2.45 MPa, matching well with that of cancellous bone. The addition of HAp into the CS matrix efficiently decreased the swelling percentage of the CS/HAp scaffolds and retained the suitable degradation rate of the composite scaffolds; the degradation percentage of the CS/HAp scaffolds was 46.37% after 28 days immersed in a physiological solution. The CS/HAp scaffolds demonstrated a higher biomineralization capability than that of the CS scaffolds, releasing a bone-like apatite layer on their surface after 15 days of incubation in simulated body fluids. The presence of HAp mimicking biological apatite in the composite scaffolds facilitated a higher protein adsorption capability, compared to that of the CS scaffolds. The obtained results suggest that the CS/HAp scaffolds have great potential as biocompatible materials for BTE applications.

[Relationship between Arsenic (+3 Oxidation State) Methyltransferase Genetic Polymorphisms and Methylation Capacity of Inorganic Arsenic].

Arsenic metabolism affects the susceptibility of humans to arsenic toxicity; therefore, clarification of the factors associated with individual variations in arsenic metabolism is an important task. Genetic polymorphisms such as single nucleotide polymorphisms (SNPs) in arsenic (+3 oxidation state) methyltransferase (AS3MT), which can methylate arsenic compounds using S-adenosyl-l-methionine (AdoMet), have been reported to modify arsenic methylation. In this review, we summarize studies conducted by us in Vietnam and by others on the association of AS3MT genetic polymorphisms with arsenic metabolism as well as human health effects. Most of the SNPs in AS3MT showed inconsistent results in terms of genotype-dependent differences in arsenic metabolism among the studies. However, AS3MT 12390 (rs3740393) and 14458 (rs11191439) were consistently related to arsenic methylation regardless of the study population: AS3MT 12390 (rs3740393) affected the second step of methylation of arsenic, whereas 14458 (rs11191439) affected the first methylation step.

Residue profiles of organohalogen compounds in human serum from e-waste recycling sites in North Vietnam: Association with thyroid hormone levels.

This study demonstrated the contamination levels of polychlorinated biphenyls (PCBs), hydroxylated PCBs (OH-PCBs), polybrominated diphenyl ethers (PBDEs), methoxylated PBDEs (MeO-PBDEs), hydroxylated PBDEs (OH-PBDEs), and bromophenols (BPhs), and their relationships with thyroid hormones (THs), in the serum of human donors from an e-waste recycling site and a rural site in Hung Yen province, Vietnam. Occupationally related exposure was indicated by significantly higher residue levels of PCBs, OH-PCBs, PBDEs, and BPhs in the serum of donors from the e-waste recycling site (median: 420, 160, 290, and 300pgg(-1) wet wt, respectively) than those in the serum of donors from the rural site (median: 290, 82, 230, and 200pgg(-)(1) wet wt, respectively). On the other hand, levels of OH-/MeO-PBDEs were significantly higher in serum of donors from the reference site (median: 160 and 20pgg(-1) wet wt, respectively) than in those from the e-waste recycling site (median: 43 and 0.52pgg(-1) wet wt, respectively). In addition, we implemented stepwise generalized linear models to assess the association between the levels of TH and PCBs, PBDEs, and their related compounds. In females, we found positive associations of PCBs and OH-PCB concentrations with total thyroxine, free thyroxine, total triiodothyronine, and free triiodothyronine, and a negative association with thyroid-stimulating hormone concentrations.

Adsorption and desorption of arsenic to aquifer sediment on the Red River floodplain at Nam Du, Vietnam.

The adsorption of arsenic onto aquifer sediment from the Red River floodplain, Vietnam, was determined in a series of batch experiments. Due to water supply pumping, river water infiltrates into the aquifer at the field site and has leached the uppermost aquifer sediments. The leached sediments, remain anoxic but contain little reactive arsenic and iron, and are used in our experiments. The adsorption and desorption experiments were carried out by addition or removal of arsenic from the aqueous phase in sediment suspensions under strictly anoxic conditions. Also the effects of HCO3, Fe(II), PO4 and Si on arsenic adsorption were explored. The results show much stronger adsorption of As(V) as compared to As(III), full reversibility for As(III) adsorption and less so for As(V). The presence or absence of HCO3 did not influence arsenic adsorption. Fe(II) enhanced As(V) sorption but did not influence the adsorption of As(III) in any way. During simultaneous adsorption of As(III) and Fe(II), As(III) was found to be fully desorbable while Fe(II) was completely irreversibly adsorbed and clearly the two sorption processes are uncoupled. Phosphate was the only solute that significantly could displace As(III) from the sediment surface. Compiling literature data on arsenic adsorption to aquifer sediment in Vietnam and Bangladesh revealed As(III) isotherms to be almost identical regardless of the nature of the sediment or the site of sampling. In contrast, there was a large variation in As(V) adsorption isotherms between studies. A tentative conclusion is that As(III) and As(V) are not adsorbing onto the same sediment surface sites. The adsorption behavior of arsenic onto aquifer sediments and synthetic Fe-oxides is compared. Particularly, the much stronger adsorption of As(V) than of As(III) onto Red River as well as on most Bangladesh aquifer sediments, indicates that the perception that arsenic, phosphate and other species compete for the same surface sites of iron oxides in sediments with properties similar to those of, for example a synthetic goethite, probably is not correct. A simple two-component Langmuir adsorption model was constructed to quantitatively describe the reactive transport of As(III) and PO4 in the aquifer.

Gold-linked electrochemical immunoassay on single-walled carbon nanotube for highly sensitive detection of human chorionic gonadotropin hormone.

A new sensitive gold-linked electrochemical immunoassay (GLEIA) for the detection of the pregnancy marker human chorionic gonadotropin (hCG) has been developed using the direct electrochemical detection of Au nanoparticles. We utilized single-walled carbon nanotube (SWCNT) microelectrodes; 24 SWCNT microelectrodes were arrayed on a single Si substrate 25×30 mm² in size, for the development of a new GLEIA (SWCNT-GLEIA). This SWCNT-GLEIA provided convenient and cost-effective tests with the required antibody and antigen sample volumes as small as 2.0 µL for a group of 4 SWCNT microelectrodes. In addition, this assay also exhibited properties of high sensitivity and selectivity benefitting from the intrinsic extraordinary features of SWCNTs. Using scanning electron microscopy, we also observed Au nanoparticle-labeled antigen-antibody complexes immobilized on the surface of the SWCNT microelectrodes. The concentration of the pregnancy marker (hCG) showed a linear relationship with the current intensity obtained from differential pulse voltammetry measurements with a limit of detection (LOD) of 2.4 pg/mL (0.024 mIU/mL) hCG. This LOD is 15 times more sensitive than a previous GLEIA, which used screen-printed carbon electrodes.

Fatal respiratory infections associated with rhinovirus outbreak, Vietnam.

During an outbreak of severe acute respiratory infections in 2 orphanages, Vietnam, 7/12 hospitalized children died. All hospitalized children and 26/43 children from outbreak orphanages tested positive for rhinovirus versus 9/40 control children (p = 0.0005). Outbreak rhinoviruses formed a distinct genetic cluster. Human rhinovirus is an underappreciated cause of severe pneumonia in vulnerable groups.

Detection of the sul1, sul2, and sul3 genes in sulfonamide-resistant bacteria from wastewater and shrimp ponds of north Vietnam.

To assess the presence and distribution of the sul genes (sul1, sul2, and sul3) and plasmids in human-mediated environments of north Vietnam, we examined a total of 127 sulfonamide-resistant (SR) bacterial isolates from four shrimp ponds (HNAQs), a city canal (HNCs) and three fish ponds that received wastewater directly from swine farms (HNPs). Results from the SR isolates revealed that sul genes were most frequently detected in the HNPs (92.0%), followed by HNCs (72.0%), and the HNAQs (43.0%). Among the sul genes detected, sul1 was the most prevalent gene in all three environments (57.0, 33.0 and 60.0% in HNPs, HNAQs, and HNCs, respectively) followed by sul2 (51.0, 19.0, and 20.0%, respectively) and sul3 (14.0, 6.0, and 8.0%, respectively). All combinations of paired different sul genes were detected, with the combination between sul1 and sul2 being the most frequent in all three environments (20.0, 8.0, and 8.0% in HNPs, HNAQs, and HNCs, respectively). The combination of three sul genes was detected at low frequencies (2-3%) in the HNPs and HNAQs, and was absent in the HNCs. The sul genes were more frequently located on the chromosome than on plasmids. The identification of SR isolates positive for the sul genes and plasmids showed that Acinetobacter was the most dominant. Our study revealed that the sul genes were common in SR bacteria from the aquatic environments we examined from northern Vietnam. Wastewater from swine farms might be "hot spots" of the sul genes and plasmids and may be reservoirs for the exchange of the sul genes among bacteria.