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1.
J Public Health Manag Pract ; 30(2): 213-220, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38271103

RESUMO

INTRODUCTION: The World Health Organization (WHO) recommends tenofovir disoproxil fumarate (TDF) for pregnant women with hepatitis B virus (HBV) presenting with HBV DNA levels of 106 copies/mL or more to hinder mother-to-child transmission (MTCT). Moreover, it is suggested that neonates of HBV-infected mothers receive an HBV vaccine birth dose within 24 hours of birth to mitigate transmission risk. METHODOLOGY: The study included 661 HBV-infected pregnant women and 316 infants from 3 hospitals in Southern Vietnam between October 2019 and November 2020. Infants were classified on the basis of their mothers' TDF prophylaxis into I-TDF (+) group (107 infants) whose mothers received TDF; I-TDF (-) group (56 infants) whose mothers missed TDF; and I-NTDF group (153 infants) whose mothers did not necessitate TDF. Almost all infants received an HBV vaccine birth dose with HBIG administered on the basis of parents' financial standing. RESULTS: MTCT was found in 2.2% of the cases. The respective MTCT rates for I-TDF (+), I-TDF (-), and I-NTDF groups were 2.8%, 5.4%, and 0.7%. Immune response rates to the HBV vaccination in the total cohort, I-TDF (+), I-TDF (-), and I-NTDF groups, were 88.6%, 87.9%, 85.7%, and 90.2%, respectively. Vaccinated infants exhibited a statistically lower risk of HBV infection postbirth (aRR = 0.1; 95% confidence interval, 0.0-0.6; P = .01). CONCLUSION: TDF can equate the MTCT risk in pregnant women with HBV DNA levels of 106 copies/mL or more to those with lower levels. Early administration of the HBV vaccine postbirth also effectively curtails MTCT. Thus, expanding TDF prophylaxis and vaccine coverage is pivotal to impede MTCT.


Assuntos
Hepatite B , Complicações Infecciosas na Gravidez , Vacinas , Lactente , Recém-Nascido , Feminino , Gravidez , Humanos , Vírus da Hepatite B , Antivirais/uso terapêutico , Transmissão Vertical de Doenças Infecciosas/prevenção & controle , DNA Viral/uso terapêutico , Vietnã/epidemiologia , Carga Viral , Hepatite B/prevenção & controle , Tenofovir/uso terapêutico , Vacinas/uso terapêutico
2.
J Infect Dev Ctries ; 17(10): 1489-1492, 2023 10 31.
Artigo em Inglês | MEDLINE | ID: mdl-37956384

RESUMO

INTRODUCTION: Using tenofovir disoproxil fumarate (TDF) is recommended in the 3rd trimester for pregnant women with HBV DNA ≥ 200,000 IU/mL to prevent mother-to-child transmission (MTCT) of hepatitis B virus (HBV). However, HBV DNA quantification is unavailable in many resource-limited areas worldwide, hence prophylaxis is often missed. The aim of this study was to determine whether HBeAg or qHBsAg is a better alternative to HBV DNA testing in HBV-infected pregnant women. METHODOLOGY: In this prospective cohort study, pregnant women with HBV infection were recruited in 3 hospitals from October 2019 to November 2020. Socio-demographic and clinical data were collected. Blood samples were taken for qHBsAg and HBV DNA testing. HBeAg results were collected from the medical records of the participants who visited a doctor during the study. RESULTS: 465 pregnant women met the study criteria. 41.9% were HBeAg positive, 33.3% had high qHBsAg levels (> 104 IU/mL), 38.3% had high HBV DNA levels (≥ 200,000 IU/mL). Pregnant women with high qHBsAg levels were 27 times more likely to have high HBV DNA levels (aOR = 27.0, 95% CI: 11.1-65.5, p < 0.001). Participants who were HBeAg positive were 57.5 times more likely to have high HBV DNA levels (aOR = 57.5, 95% CI: 23.0-140.0, p < 0.001). The sensitivity of qHBsAg and HBeAg was 80% and 94%, respectively; and specificity was 95% and 90%, respectively. CONCLUSIONS: HBeAg testing should be considered over qHBsAg assay as an alternative to HBV DNA assay because of its technical simplicity, lower cost, and fewer missed treatments.


Assuntos
Hepatite B Crônica , Complicações Infecciosas na Gravidez , Feminino , Humanos , Gravidez , Vírus da Hepatite B/genética , Antígenos de Superfície da Hepatite B , Antígenos E da Hepatite B , Gestantes , DNA Viral , Estudos Prospectivos , Transmissão Vertical de Doenças Infecciosas/prevenção & controle , Complicações Infecciosas na Gravidez/diagnóstico , Complicações Infecciosas na Gravidez/tratamento farmacológico , Hepatite B Crônica/diagnóstico , Hepatite B Crônica/tratamento farmacológico
3.
Chem Asian J ; 18(17): e202300404, 2023 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-37440587

RESUMO

Highly positively charged poly(vinyl benzyl trimethylammonium chloride) (PVBMA) was successfully synthesized with approximately 82% of yield. The PVBMA was characterized by the molecular weight (Mw ) of 343.45 g mol-1 and the molecular weight distribution, (D) of 2.4 by 1 H NMR and SEC measurements. The PVBMA was applied as an effective agent for α-Al2 O3 surface modification in the adsorptive removal of the azo dye acid orange G (AOG). The AOG removal performance was significantly enhanced at all pH compared to without surface modification. The experimental parameters were optimal at pH 8, free ionic strength, 15 min of adsorption time, and 5 mg mL-1 α-Al2 O3 adsorbents. The AOG adsorption which was mainly controlled by the PVBMA-AOG electrostatic attractions was better applicable to the Langmuir isotherm and the pseudo-second kinetic model. The PVBMA-modified α-Al2 O3 demonstrates a high-performance and highly reusable adsorbent with great AOG performances of approximately 90.1% after 6 reused cycles.

4.
Mar Pollut Bull ; 182: 114023, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35973243

RESUMO

Plastic pollution in the ocean primarily originates from the land-derived mismanaged plastic waste that is transported by rivers. This study aimed to estimate the plastic litter generation in the surface water in Jakarta and Indonesia. A field survey was conducted at six riverine sampling points (upstream to downstream) and three holding facilities of the litter in Jakarta during the rainy season. The Jakarta Open Data database was used to estimate the tonnage of plastic litter. By mass, plastic comprised approximately 74 % of the anthropogenic litter in rivers and 87 % in holding facilities. The riverine plastic proportion slightly increased downstream. Approximately 9.9 g/person/day of plastic litter was discharged into Jakarta's surface water during rainy season and recovered by floating booms. To reduce plastic pollution and its severe impacts on aquatic ecosystems and human health, further field investigation is necessary to design an effective clean-up system and litter-prevention strategy.


Assuntos
Ecossistema , Plásticos , Monitoramento Ambiental , Humanos , Indonésia , Resíduos/análise , Água
5.
Commun Biol ; 5(1): 752, 2022 07 28.
Artigo em Inglês | MEDLINE | ID: mdl-35902767

RESUMO

Escherichia coli lineage ST131 is an important cause of urinary tract and bloodstream infections worldwide and is highly resistant to antimicrobials. Specific ST131 lineages carrying invasiveness-associated papGII pathogenicity islands (PAIs) were previously described, but it is unknown how invasiveness relates to the acquisition of antimicrobial resistance (AMR). In this study, we analysed 1638 ST131 genomes and found that papGII+ isolates carry significantly more AMR genes than papGII-negative isolates, suggesting a convergence of virulence and AMR. The prevalence of papGII+ isolates among human clinical ST131 isolates increased dramatically since 2005, accounting for half of the recent E. coli bloodstream isolates. Emerging papGII+ lineages within clade C2 were characterized by a chromosomally integrated blaCTX-M-15 and the loss and replacement of F2:A1:B- plasmids. Convergence of virulence and AMR is worrying, and further dissemination of papGII+ ST131 lineages may lead to a rise in severe and difficult-to-treat extraintestinal infections.


Assuntos
Infecções por Escherichia coli , Escherichia coli , Adesinas de Escherichia coli , Antibacterianos/farmacologia , Farmacorresistência Bacteriana/genética , Infecções por Escherichia coli/tratamento farmacológico , Infecções por Escherichia coli/epidemiologia , Infecções por Escherichia coli/genética , Humanos , Virulência/genética
6.
Tob Control ; 2022 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-35896377

RESUMO

BACKGROUND: Tobacco consumption places a significant economic burden on households, which is particularly severe in developing countries like Vietnam. In a country where the social insurance system is weak and healthcare is often expensive, tobacco-consuming households may face a higher risk of living in poverty. Some evidence on the social consequences of tobacco consumption suggests that it might aggravate poverty and inequality in Vietnam; however, to the best of our knowledge, no research provides a reliable estimate of the impoverishing effect of tobacco use in the country thus far. OBJECTIVES: This study quantifies the direct impact of tobacco use on poverty, measured by a poverty head count and the total size of the poverty gap in Vietnam in 2018. METHODS: By deducting tobacco-related expenditure from the total household income, the authors recalculate the actual household disposable income and examine whether the households suffer from the state of secondary poverty. Data from the 2018 Vietnam Household Living Standards Survey were used for calculation. RESULTS: (1) Total tobacco-related expenditure increased the number of poor people by 305 090 (0.31% of the country's population) in 2018. More than one-third of those impoverished people are children, who should be considered victims of adults' tobacco use. (2) Tobacco use increased the poverty gap by 0.08 percentage points from 2.20% to 2.28%. (3) The impoverishment effects of tobacco consumption vary across groups in society and appear to be more intense in rural areas, among ethnic minorities and in the two lowest quintiles of consumption. CONCLUSION: This study confirms the impoverishing effect of tobacco use in Vietnam (305 090 people) and that the effects are heterogeneous across population groups. Therefore, controlling tobacco use should be a part of the broader poverty reduction strategy in Vietnam and should be wisely targeted so as to reduce poverty effectively.

7.
Eur J Clin Nutr ; 76(11): 1590-1593, 2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-35411029

RESUMO

This pilot study aimed to evaluate the effectiveness of peer-led education intervention on physical activity, sedentary behaviours, and dietary behaviours among adolescents in HCM city, Vietnam. Among students in the intervention arm after a 9-month follow-up, total energy intake was reduced by 304 kcal/day, fat by 13 g/day, carbohydrate by 39 g/day, and sweet foods by 20 g/day, compared to pre-intervention figures (p < 0.05, adjusted for age, BMI at baseline, gender, the interaction between measurement time and intervention groups, and cluster effect in schools). Only total energy intake was significantly lower in the intervention than control students (p < 0.05, after adjustment). Our pilot project has established the feasibility of a peer-led intervention to improve lifestyles among adolescents in HCM city and evidence of improvements in dietary intake. Australian New Zealand Clinical Trials Registry: ACTRN12619000421134.


Assuntos
Exercício Físico , Humanos , Adolescente , Projetos Piloto , Vietnã , Inquéritos e Questionários , Austrália
8.
Blood Press ; 30(6): 386-394, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34664539

RESUMO

PURPOSE: Hypertension is common in kidney transplant recipients (KTRs). For the evaluation of blood pressure (BP), 24-h ambulatory BP measurements (ABPM) are considered superior to usual office measurements but are also resource demanding and troublesome to many patients. We therefore evaluated the use of unattended automated office BP (AOBP) during the first year following living donor kidney transplantation and compared AOBP with ABPM as obtained 12 months after transplantation. MATERIALS AND METHODS: Data were retrieved from a cohort of 57 KTRs (mean age 45 ± 14 years, 75% males) who all received kidneys from living donors and had a good graft function (estimated glomerular filtration rate (eGFR) 52 ± 16 ml/min/1.73 m2 at 12 months). Unattended AOBP was measured at each visit to the outpatient clinic using the BpTru® device, while ABPM was obtained by Spacelabs® equipment before and 12 months after transplantation. RESULTS: AOBP remained stable from month 2 (130.2 ± 10.8/82.2 ± 7.8 mmHg) to month 12 (129.0 ± 12.8/83.1 ± 9.6 mmHg) post-transplantation. At 12 months follow-up, ambulatory daytime systolic BP was slightly higher than AOBP (132.7 ± 10.7 vs. 129.4 ± 12.2 mmHg, p = 0.04), while diastolic BP was similar (82.7 ± 7.7 vs. 82.0 ± 10.2 mmHg). Using Bland-Altman plots, 95% limits of agreements were -17.9 to 24.5 mmHg for systolic and -16.5 to 15.1 mmHg for diastolic BP. When considering a target BP of ≤130/<80 mmHg, 62% had sustained hypertension, 9% white coat hypertension and 11% masked hypertension. Using multiple linear regression analysis, only urine albumin-creatinine ratio tended to predict a higher systolic AOBP (p = 0.07). CONCLUSION: In a cohort of stable living donor KTRs, mean values of unattended AOBP using BpTru® are comparable to daytime ABPM with a misclassification rate of approximately 20%.


Assuntos
Hipertensão , Transplante de Rim , Adulto , Pressão Sanguínea , Determinação da Pressão Arterial , Monitorização Ambulatorial da Pressão Arterial , Feminino , Humanos , Hipertensão/diagnóstico , Transplante de Rim/efeitos adversos , Doadores Vivos , Masculino , Pessoa de Meia-Idade , Visita a Consultório Médico
9.
Lancet Reg Health West Pac ; 11: 100163, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34327365

RESUMO

BACKGROUND: In 2016-2017, 68 women in Southern Vietnam had RT-PCR confirmed Zika virus (ZIKV) infection during pregnancy. We report here the outcomes of the pregnancies and the virological analyses related to this outbreak. METHODS: We collected clinical and epidemiological information from the women who were enrolled in the study. Medical records related to the pregnancy in 2016-2017 were retrieved for those who were not able to be enrolled in the study. Children born to women with ZIKV infection during pregnancy were also enrolled. Serum samples were evaluated for presence of ZIKV antibodies. Phylogenetic analyses were performed on Zika virus genomes sequenced from the 2016-2017 serum samples. FINDINGS: Of the 68 pregnancies, 58 were livebirths and 10 were medically terminated. Four of the medical records from cases of fetal demise were able to be retrieved, of which one was consistent with congenital ZIKV infection. Of the 58 women with a livebirth, 21 participated in the follow-up investigation. All but two women had serologic evidence of ZIKV infection. Of the 21 children included in the study (mean age: 30.3 months), 3 had microcephaly at birth. No other clinical abnormalities were reported and no differences in neurodevelopment were observed compared to a control group. Phylogenetic analysis revealed a clade within the ZIKV Asian lineage and branch at the root of samples from the 2013-2014 French Polynesian outbreak. The prM S139N mutation was not observed. INTERPRETATION: We have been able to demonstrate a clade within the ZIKV Asian lineage implicated in adverse pregnancy outcomes in Southern Vietnam. FUNDING: INCEPTION project (PIA/ANR-16-CONV-0005) and a grant received from BNP Paribas Simplidon.

10.
J Paediatr Child Health ; 57(8): 1267-1273, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-33739547

RESUMO

AIM: The paediatric population has a low adherence and acceptance rate of unpalatable medicines. This study aimed to determine whether eating chocolate immediately prior to drug administration would help to mask the bitter taste of a drug. The difference in taste masking efficacy between white, milk and dark chocolate was a secondary measure outcome. METHODS: A controlled repeated measures crossover taste trial was conducted using a taste panel of 29 young healthy adults who met the criteria to differentiate intensity in bitterness taste. Participants separately tasted solutions of quinine, flucloxacillin and clindamycin using the swill and spit method, singularly and following blinded prior administration of white, milk or dark chocolate. Drug solutions administered without prior chocolate served as controls. Bitterness score for each tasting was recorded using a 5-point scale. RESULTS: Regardless of chocolate type, mean taste scores with prior chocolate for quinine (range 2.00-2.34), clindamycin (3.72-3.83) and flucloxacillin (3.38-3.45) were all lower than mean scores for respective drugs without chocolate (3.24, 4.75 and 4.28, respectively; P < 0.0001 for all comparisons). Dark chocolate was most efficacious for masking the bitter taste of quinine, but the differences in taste masking efficacy between dark, milk and white chocolates were not statistically significant for flucloxacillin and clindamycin. CONCLUSIONS: Prior administration of chocolate results in lower perceived bitterness compared to control tastings of quinine, flucloxacillin and clindamycin solutions; however, there is no clear difference in this effect between the dark, milk and white chocolates used in this study.


Assuntos
Chocolate , Preparações Farmacêuticas , Adulto , Animais , Criança , Humanos , Leite , Quinina , Paladar
11.
Clin Microbiol Infect ; 27(10): 1515.e1-1515.e8, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33476808

RESUMO

OBJECTIVES: We performed a One Health surveillance in Hanoi-a region with a high-density human population and livestock production, and a recognized hotspot of animal-associated antimicrobial resistance (AMR)-to study the contribution of blaCTX-M-carrying Escherichia coli and plasmids from food-animal sources in causing human community-acquired urinary tract infections (CA-UTIs). METHODS: During 2014-2015, 9090 samples were collected from CA-UTI patients (urine, n = 8564), pigs/chickens from farms and slaughterhouses (faeces, carcasses, n = 448), and from the slaughterhouse environment (surface swabs, water, n = 78). E. coli was identified in 2084 samples. Extended-spectrum ß-lactamase (ESBL) production was confirmed in 235 and blaCTX-M in 198 strains by PCR with short-read plasmid sequencing. Fourteen strains were long-read sequenced to enable plasmid reconstruction. RESULTS: The majority of the ESBL-producing E. coli strains harboured blaCTX-M (n = 198/235, 84%). High clonal diversity (48 sequence types, STs) and distinct, dominant STs in human sources (ST1193, n = 38/137; ST131, n = 30/137) and non-human sources (ST155, n = 25/61) indicated lack of clonal transmission between habitats. Eight blaCTX-M variants were identified; five were present in at least two sample sources. Human and food-animal strains did not show similar plasmids carrying shared blaCTX-M genes. However, IS6 elements flanking ISEcp1-blaCTX-M-orf477/IS903B structures were common across habitats. CONCLUSIONS: In this study, animal-associated blaCTX-ME. coli strains or blaCTX-M plasmids were not direct sources of CA-UTIs or ESBL resistance in humans, respectively, suggesting evolutionary bottlenecks to their adaptation to a new host species. Presence of common IS6 elements flanking blaCTX-M variants in different plasmid backbones, however, highlighted the potential of these transposable elements for AMR transmission either within or across habitats.


Assuntos
Infecções por Escherichia coli , Escherichia coli/genética , Contaminação de Alimentos/análise , Saúde Única , Infecções Urinárias , Animais , Antibacterianos , Galinhas , Infecções por Escherichia coli/epidemiologia , Infecções por Escherichia coli/veterinária , Cadeia Alimentar , Microbiologia de Alimentos , Humanos , Plasmídeos/genética , Estudos Prospectivos , Suínos , Infecções Urinárias/epidemiologia , Vietnã/epidemiologia , beta-Lactamases/genética
13.
Polymers (Basel) ; 12(7)2020 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-32674270

RESUMO

This study aims to investigate the adsorption behavior of a strong polyelectrolyte poly(styrenesulfonate) (PSS) onto alumina particles. Adsorption of PSS onto positively charged alumina surface increased with increasing ionic strength, indicating that non-electrostatic and electrostatic interaction controlled the adsorption. The removal of an emerging antibiotic ciprofloxacin (CFX) from water environment using PSS-modified alumina (PMA) was also studied. The removal of CFX using PMA was much higher than that using alumina particles without PSS modification in all pH ranges of 2-11. The removal of CFX reached 98% under the optimum conditions of pH 6, contact time of 120 min, adsorbent dosage of five milligrams per milliliter and ionic strength 104-M NaCl. The adsorption isotherms of CFX at different salt concentrations fit well with a two-step adsorption model, while the adsorption kinetic fit well with a pseudo-second-order model with a good correlation coefficient (R2 > 0.9969). The CFX-removal from a hospital wastewater using PMA was more than 75%. Our study demonstrates that adsorption of PSS onto alumina to modify the particle surface is important to form a novel adsorbent PMA for CFX-removal from water environments.

14.
Polymers (Basel) ; 10(2)2018 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-30966259

RESUMO

Well-defined poly(tert-butyldimethylsilyl methacrylate)s (TBDMSMA) were prepared by the reversible addition-fragmentation chain transfer (RAFT) process using cyanoisopropyl dithiobenzoate (CPDB) as chain-transfer agents (CTA). The experimentally obtained molecular weight distributions are narrow and shift linearly with monomer conversion. Propagation rate coefficients (kp) and termination rate coefficients (kt) for free radical polymerization of TBDMSMA have been determined for a range of temperature between 50 and 80 °C using the pulsed laser polymerization-size-exclusion chromatography (PLP-SEC) method and the kinetic method via steady-state rate measurement, respectively. The CPDB-mediated RAFT polymerization of TBDMSMA has been subjected to a combined experimental and PREDICI modeling study at 70 °C. The rate coefficient for the addition reaction to RAFT agent (kß1, kß2) and to polymeric RAFT agent (kß) is estimated to be approximately 1.8 × 104 L·mol-1·s-1 and for the fragmentation reaction of intermediate RAFT radicals in the pre-equilibrium (k-ß1, k-ß2) and main equilibrium (k-ß) is close to 2.0 × 10-2 s-1. The transfer rate coefficient (ktr) to cyanoisopropyl dithiobenzoate is found to be close to 9.0 × 10³ L·mol-1·s-1 and the chain-transfer constant (Ctr) for CPDB-mediated RAFT polymerization of TBDMSMA is about 9.3.

15.
Curr Drug Metab ; 18(2): 145-156, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28093997

RESUMO

Sonication-assisted nanoprecipitation provides an effective tool for nanomedicine engineering in therapeutic improvement. In the scope of this review, original works in interdisciplinary areas of using sonication with precipitation method for nanoparticulate drug delivery systems and its applications in management of different diseases are discussed. The use of sonication-assisted nanoprecipitation has been proved to improve drug bioavailability, which attracts tremendous interests as an effective strategy for drug delivery. However, many challenges still remain. To overcome these barriers, different approaches such as precipitation method, rational design, optimization and modification have been investigated. Accordingly, current knowledge of sonication-assisted nanoprecipitation proposes a broad perspective and optimization for the applications of nanotechnology in drug delivery.


Assuntos
Nanopartículas/química , Precipitação Química , Sistemas de Liberação de Medicamentos , Liberação Controlada de Fármacos , Nanopartículas/administração & dosagem , Nanopartículas/uso terapêutico , Nanotecnologia , Sonicação
16.
Biomacromolecules ; 17(4): 1339-46, 2016 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-26938371

RESUMO

In this paper, we describe a simple and powerful way to synthesize antibacterial biomaterials with applications as implants in orthopedic surgery. Such implants are obtained by covalently grafting onto the Ti90A16 V4 alloy surface with vancomycin-functionalized nanoparticles. Nanoparticles were produced by ring-opening metathesis polymerization of α-norbornenyl-ω-vancomycin poly(ethylene oxide) macromonomers. Vancomycin is an interesting candidate because of its use in the field of implant associated infection as it is a glycopeptide which acts on bacterial walls. As a consequence, vancomycin does not need to be released for it to be active. In the first part of this paper, the synthesis and the complete characterization of these materials are described. In a second part, the in vitro antibacterial behavior is analyzed and discussed.


Assuntos
Antibacterianos/química , Materiais Revestidos Biocompatíveis/síntese química , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Nanopartículas/química , Próteses e Implantes/microbiologia , Vancomicina/química , Antibacterianos/farmacologia , Materiais Revestidos Biocompatíveis/química , Staphylococcus aureus Resistente à Meticilina/crescimento & desenvolvimento , Testes de Sensibilidade Microbiana , Polietilenoglicóis/química , Propriedades de Superfície , Titânio/química , Vancomicina/farmacologia
17.
Chemosphere ; 119: 371-376, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25061942

RESUMO

In rice, Si assimilated from the soil solution is deposited in inter- and intracellular spaces throughout the leaf and stems to form silicified structures (so-called phytoliths). Because K is also present in significant concentrations in rice stems and leaves, the question arises if K is immobilized in the mineralized silica during the precipitation of Si. This work determined whether desilification of the phytolith is a factor regulating K release by implementing batch experiments. Solubility of Si and K of the rice straw heated at different temperatures were examined to identify effect of pretreatment. Analyses of phytoliths using SEM-EDX and X-ray tomographic microscopy in conjunction with the results from batch experiments revealed that K might co-exist with occluded organic matter inside the phytolith structure. In the kinetic experiments, corresponding increases of K and Si concentrations in the supernatants were observed which suggested that desilification of the phytolith is a main factor regulating K release. The extent of heat pretreatment of the rice straw is of significant importance with respect to dissolution of the phytolith by affecting organic removal and surface modification. At temperatures lower than 600 °C, corresponding increases of the soluble Si and K with heating temperature have been obviously observed. In contrast, the solubility of Si and K gradually decreased at temperatures above 600 °C. This work provides insights into factors that control release of K and Si from phytolith and a practical recommendation for practices of burning rice straw that may maximize subsequent release of Si and K for crops.


Assuntos
Oryza/química , Potássio/química , Silício/química , Dióxido de Silício/química , Solubilidade , Temperatura
18.
Int J Pharm ; 474(1-2): 146-50, 2014 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-25138256

RESUMO

The aims of this study are to increase and explain the mechanism of dissolution enhancement of isradipine using the sonoprecipitation method for stable nanosuspensions. There have been still few of published researches on formulation of isradipine using nanoparticle engineering. Nanosuspension systems were prepared upon various factors including amplitude and the time length of ultrasonication. The dissolution test was performed according to the USP paddle method in intestinal fluid (pH 6.8). The crystalline structure of drug, the molecular interaction, morphology and size of nanosuspension were also investigated to determine the mechanism of dissolution enhancement. The sonoprecipitation method with use of HPMC 6 showed its potential in enhancement of the drug release rate. Stable nanosuspension was significantly depended on amplitude and time of ultrasonication since these factors affected on the size of nanoparticles. The synergistic effects of reduction of drug crystallinity and particle size could increase the dissolution rate of isradipine by providing a stable nanosuspension. This work may contribute to a new strategy for improvement dissolution rate of isradipine.


Assuntos
Precipitação Química , Isradipino/química , Nanopartículas/química , Sonicação , Cromatografia Líquida de Alta Pressão , Tamanho da Partícula , Propriedades de Superfície , Suspensões/química
19.
Biomacromolecules ; 13(3): 896-904, 2012 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-22288777

RESUMO

This work reports on the synthesis of titanium bone implants functionalized with nanoparticles (NPs) containing Arg-Gly-Asp-Cys peptide (RGDC) and shows the adhesion behavior of cells seeded on these materials. RGDC peptides were first conjugated to a norbornenyl-poly(ethylene oxide) macromonomer (Nb-PEO). Then, functional NPs with a size of ∼300 nm and constituted of polynorbornene core surrounded by poly(ethylene oxide) shell were prepared by ring-opening metathesis polymerization in dispersed medium. The grafting density of these NPs on the titanium surface is up to 2 NPs·µm(-2) (80 pmol of RGDC per cm(-2) of NP surface). Cell adhesion was evaluated using preosteoblast cells (MC3T3-E1). Results of cells cultured for 24 h showed that materials grafted with NPs functionalized with RGDC peptides enhance specific cell adhesion and can create filopodia-like structures among NP sites by stressing the cells.


Assuntos
Adesão Celular , Materiais Revestidos Biocompatíveis/química , Nanopartículas , Oligopeptídeos/química , Osteoblastos/metabolismo , Titânio/química , Animais , Células Cultivadas , Materiais Revestidos Biocompatíveis/metabolismo , Teste de Materiais , Camundongos , Osteoblastos/citologia , Polietilenoglicóis/química , Próteses e Implantes , Crânio/citologia , Crânio/metabolismo , Propriedades de Superfície
20.
Langmuir ; 25(17): 9633-8, 2009 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-19634873

RESUMO

Diazonium salt chemistry and atom transfer radical polymerization (ATRP) were combined in view of preparing new bioactive hairy diamond nanoparticles containing, or potentially containing, nitrogen-vacancy (NV) fluorescent centers (fluorescent nanodiamonds, or fNDs). fNDs were modified by ATRP initiators using the electroless reduction of the diazonium salt BF(4)(-),(+)N(2)-C(6)H(4)-CH(CH(3))-Br. The strongly bound aryl groups -C(6)H(4)-CH(CH(3))-Br efficiently initiated the ATRP of tert-butyl methacrylate (tBMA) at the surface of the nanodiamonds, which resulted in obtaining ND-PtBMA hybrids. The grafted chain thickness, estimated from X-ray photoelectron spectroscopy (XPS), was found to increase linearly with respect to time before reaching a plateau value of ca. 2 nm. These nanoobjects were further hydrolyzed into ND-PMAA (where PMAA is the poly(methacrylic acid) graft) and further decorated by bovine serum albumin through the 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS) coupling procedure.


Assuntos
Nanopartículas/química , Proteínas/química , Animais , Bovinos , Diamante/química , Compostos de Diazônio/química , Microanálise por Sonda Eletrônica/métodos , Fluorescência , Hidrólise , Metacrilatos/química , Microscopia Eletrônica de Transmissão/métodos , Nanotecnologia/métodos , Nitrogênio/química , Polímeros/química , Sais/química , Albumina Sérica/química
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