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1.
J Infect Dis ; 229(1): 273-281, 2024 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-38051631

RESUMO

BACKGROUND: Clostridioides difficile infection (CDI) is a common healthcare-associated infection with limited treatment options. Omadacycline, an aminomethylcycline tetracycline, has potent in vitro activity against C difficile and a low propensity to cause CDI in clinical trials. We aimed to assess fecal pharmacokinetics and gut microbiome effects of oral omadacycline compared to oral vancomycin in healthy adults. METHODS: This was a phase 1, nonblinded, randomized clinical trial conducted in healthy volunteers aged 18-40 years. Subjects received a 10-day course of omadacycline or vancomycin. Stool samples were collected at baseline, daily during therapy, and at follow-up visits. Omadacycline and vancomycin stool concentrations were assessed, and microbiome changes were compared. RESULTS: Sixteen healthy volunteers with a mean age of 26 (standard deviation [SD], 5) years were enrolled; 62.5% were male, and participants' mean body mass index was 23.5 (SD, 4.0) kg/m2. Omadacycline was well tolerated with no safety signal differences between the 2 antibiotics. A rapid initial increase in fecal concentrations of omadacycline was observed compared to vancomycin, with maximum concentrations achieved within 48 hours. A significant difference in alpha diversity was observed following therapy in both the omadacycline and vancomycin groups (P < .05). Bacterial abundance and beta diversity analysis showed differing microbiome changes in subjects who received omadacycline versus vancomycin. CONCLUSIONS: Subjects given omadacycline had high fecal concentrations with a distinct microbiome profile compared to vancomycin. CLINICAL TRIALS REGISTRATION: NCT06030219.


Assuntos
Infecções por Clostridium , Microbioma Gastrointestinal , Adulto , Humanos , Masculino , Feminino , Vancomicina/uso terapêutico , Voluntários Saudáveis , Antibacterianos/uso terapêutico , Tetraciclinas/farmacologia , Tetraciclinas/uso terapêutico , Infecções por Clostridium/microbiologia
2.
Clin Infect Dis ; 75(7): 1164-1170, 2022 09 30.
Artigo em Inglês | MEDLINE | ID: mdl-35134880

RESUMO

BACKGROUND: This study was the first human validation of the gram-positive bacterial DNA polymerase IIIC target in patients with Clostridioides difficile infection. The primary objectives were to assess clinical cure rates and adverse events (AEs). Secondary objectives were to evaluate plasma/fecal pharmacokinetics, microbiologic eradication, microbiome and bile acid effects, and sustained clinical cure (SCC) with ibezapolstat. METHODS: This single-arm, open-label, phase 2a study enrolled adults with C. difficile infection at 4 US centers. Patients received ibezapolstat 450 mg orally every 12 hours for 10 days and followed for an additional 28 days to assess study objectives. RESULTS: Ten patients with a mean (standard deviation [SD]) age of 49 [15] years were enrolled. Seven AEs were reported classified as mild-moderate. Plasma levels of ibezapolstat ranged from 233 to 578 ng/mL while mean (SD) fecal levels were 416 (494) µg/g stool by treatment day 3 and >1000 µg/g stool by days 8-10. A rapid increase in alpha diversity in the fecal microbiome was noted after starting ibezapolstat therapy, which was maintained after completion of therapy. A proportional decrease in Bacteroidetes phylum was observed (mean change [SD], -10.0% [4.8%]; P = .04) with a concomitantly increased proportion of Firmicutes phylum (+14.7% [5.4%]; P = .009). Compared with baseline, total primary bile acids decreased by a mean (SD) of 40.1 (9.6) ng/mg stool during therapy (P < .001) and 40.5 (14.1) ng/mg stool after completion of therapy (P = .007). Rates of both initial clinical cure and SCC at 28 days were 100% (10 of 10 patients). CONCLUSIONS: In this phase 2a study, 10 of 10 patients achieved SCC, demonstrated favorable pharmacokinetics, minimal AEs, and beneficial microbiome and bile acids results. These results support continued clinical development.


Assuntos
Antibacterianos , Clostridioides difficile , Infecções por Clostridium , Adulto , Antibacterianos/efeitos adversos , Antibacterianos/farmacocinética , Ácidos e Sais Biliares , Infecções por Clostridium/tratamento farmacológico , Infecções por Clostridium/microbiologia , DNA Polimerase Dirigida por DNA , Humanos , Pessoa de Meia-Idade
3.
Anaerobe ; 75: 102543, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35227896

RESUMO

BACKGROUND: C. difficile spores are frequently isolated from hospital and non-healthcare settings but a worldwide analysis has not been done. The study objectives were to assess C. difficile spore contamination in the hospital and non-healthcare environments across a variety of countries. METHODS: Field studies assessed hospital vs. non-healthcare C. difficile spore contamination in hospitals, non-healthcare buildings, outdoor environments, and shoes. Swabs were cultured anaerobically for C. difficile and typed using PCR-fluorescent ribotyping. C. difficile contamination by swabbing area and geographic locations were compared. FINDINGS: A total of 7,857 unique samples were collected primarily from the USA (89%) in addition to 9 other countries. The global prevalence of C difficile from environmental samples was 25.3% and did not differ between countries. In USA based studies, C. difficile contamination rates were similar for healthcare buildings (23.2%), non-healthcare buildings (23.4%), and outdoor spaces (24.7%). Floor samples had significantly higher (p < 0.001) C. difficile contamination rate (46.5%) followed by non-floor samples (21.1%), and bathrooms (15.3%). In a comparison of USA to other country samples, C. difficile contamination rates were similar for USA samples (21.5%) compared to rest of world samples (22.3%; p = 0.61). The most common ribotypes included F014-020 (15.7%), F106 (12.6%), F010 (8.9%), F027 (8.8%), and F002 (8.1%) and did not differ significantly between USA and non-USA samples. Finally, 546 of 1,218 (44.8%) shoe soles swabbed from the USA were contaminated with C. difficile spores. INTERPRETATION: This large surveillance study of several countries demonstrated high prevalence of toxigenic C. difficile in non-healthcare environments with high contamination rates from floors and shoe soles.


Assuntos
Clostridioides difficile , Infecções por Clostridium , Clostridioides , Clostridioides difficile/genética , Infecções por Clostridium/epidemiologia , Humanos , Prevalência , Ribotipagem , Esporos Bacterianos
4.
Bioorg Med Chem Lett ; 23(9): 2522-6, 2013 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-23541670

RESUMO

We report the discovery of a novel series of ATP-competitive Janus kinase 3 (JAK3) inhibitors based on the 5H-pyrrolo[2,3-b]pyrazine scaffold. The initial leads in this series, compounds 1a and 1h, showed promising potencies, but a lack of selectivity against other isoforms in the JAK family. Computational and crystallographic analysis suggested that the phenyl ether moiety possessed a favorable vector to achieve selectivity. Exploration of this vector resulted in the identification of 12b and 12d, as potent JAK3 inhibitors, demonstrating improved JAK family and kinase selectivity.


Assuntos
Janus Quinase 3/antagonistas & inibidores , Éteres Fenílicos/química , Inibidores de Proteínas Quinases/química , Piridazinas/química , Pirróis/química , Sítios de Ligação , Domínio Catalítico , Avaliação Pré-Clínica de Medicamentos , Janus Quinase 3/metabolismo , Simulação de Acoplamento Molecular , Éteres Fenílicos/síntese química , Éteres Fenílicos/metabolismo , Ligação Proteica , Isoformas de Proteínas/antagonistas & inibidores , Isoformas de Proteínas/metabolismo , Inibidores de Proteínas Quinases/síntese química , Inibidores de Proteínas Quinases/metabolismo , Relação Estrutura-Atividade
5.
Bioorg Med Chem Lett ; 23(5): 1486-92, 2013 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-23352510

RESUMO

A series of amino-pyrimidines was developed based upon an initial kinase cross-screening hit from a CDK2 program. Kinase profiling and structure-based drug design guided the optimization from the initial 1,2,3-benzotriazole hit to a potent and selective JNK inhibitor, compound 24f (JNK1 and 2 IC(50)=16 and 66 nM, respectively), with bioavailability in rats and suitable for further in vivo pharmacological evaluation.


Assuntos
Proteínas Quinases JNK Ativadas por Mitógeno/antagonistas & inibidores , Inibidores de Proteínas Quinases/química , Inibidores de Proteínas Quinases/farmacologia , Pirimidinas/química , Pirimidinas/farmacologia , Triazóis/química , Triazóis/farmacologia , Animais , Cristalografia por Raios X , Desenho de Fármacos , Humanos , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Modelos Moleculares , Inibidores de Proteínas Quinases/síntese química , Pirimidinas/síntese química , Ratos , Relação Estrutura-Atividade , Triazóis/síntese química
6.
BMJ Open ; 13(6): e070480, 2023 06 12.
Artigo em Inglês | MEDLINE | ID: mdl-37308267

RESUMO

OBJECTIVES: The objectives of this study are to identify the trend of undernutrition risk among under-five children (U5C) in Bangladesh and the trend of its correlates. DESIGN: Multiple cross-sectional data sets from different time points were used. SETTING: Nationally representative Bangladesh Demographic and Health Surveys (BDHSs) were conducted in 2007, 2011, 2014 and 2017/2018. PARTICIPANTS: In the BDHSs, the sample sizes for ever-married women (age: 15-49 years) were 5300 in 2007, 7647 in 2011, 6965 in 2014 and 7902 in 2017/2018. OUTCOMES: Extant indicators of undernutrition (stunted, wasted and underweight) have been considered as the outcome variables. MATERIALS AND METHODS: Descriptive statistics, bivariate analysis and factor loadings from factor analysis have been used to determine the prevalence of undernutrition over the years and find the trend of risk and its correlates. RESULTS: Risks of stunting among the U5C were 41.70%, 40.67%, 36.57% and 31.14%; that of wasting were 16.94%, 15.48%, 14.43% and 8.44%; and that of underweight were 39.79%, 35.80%, 32.45% and 22.46% in 2007, 2011, 2014 and 2017/2018, respectively. From the factor analysis, it has been found that the top five potential correlates of undernutrition are the wealth index, the education of the father and mother, the frequency of antenatal visits during pregnancy, the father's occupation and/or the type of place of residence in the last four consecutive surveys. CONCLUSION: This study helps us gain a better understanding of the impact of the top correlates on child undernutrition. To accelerate the reduction of child undernutrition more by 2030, Government and non-government organisations should focus on improving education and household income-generating activities among poor households and raising awareness among women about the importance of receiving antenatal care during pregnancy.


Assuntos
Desnutrição , Humanos , Feminino , Gravidez , Recém-Nascido , Lactente , Pré-Escolar , Adolescente , Adulto Jovem , Adulto , Pessoa de Meia-Idade , Masculino , Bangladesh/epidemiologia , Desnutrição/complicações , Desnutrição/epidemiologia , Síndrome de Emaciação/epidemiologia , Síndrome de Emaciação/etiologia , Magreza/epidemiologia , Magreza/etiologia , Transtornos do Crescimento/epidemiologia , Transtornos do Crescimento/etiologia , Cuidado Pré-Natal/estatística & dados numéricos , Fatores de Risco , Demografia , Análise Fatorial
7.
Interdiscip Perspect Infect Dis ; 2022: 5904332, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35698592

RESUMO

Purpose: Elderly patients are at high risk of fatality from COVID-19. The present work aims to describe the clinical characteristics of elderly inpatients with COVID-19 and identify the predictors of in-hospital mortality at admission. Materials and Methods: In this retrospective, multicenter cohort study, we included elderly COVID-19 inpatients (n = 245) from four hospitals in Sylhet, Bangladesh, who had been discharged between October 2020 and February 2021. Demographic, clinical, and laboratory data were extracted from hospital records and compared between survivors and nonsurvivors. We used univariable and multivariable logistic regression analysis to explore the risk factors associated with in-hospital death. Principal Results. Of the included patients, 202 (82.44%) were discharged and 43 (17.55%) died in hospital. Except hypertension, other comorbidities like diabetes, chronic kidney disease, ischemic heart disease, and chronic obstructive pulmonary disease were more prevalent in nonsurvivors. Nonsurvivors had a higher prevalence of leukocytosis (51.2 versus 30.7; p=0.01), lymphopenia (72.1 versus 55; p=0.05), and thrombocytopenia (20.9 versus 9.9; p=0.07). Multivariable regression analysis showed an increasing odds ratio of in-hospital death associated with older age (odds ratio 1.05, 95% CI 1.01-1.10, per year increase; p=0.009), thrombocytopenia (OR = 3.56; 95% CI 1.22-10.33, p=0.019), and admission SpO2 (OR 0.91, 95% CI 0.88-0.95; p=0.001). Conclusions: Higher age, thrombocytopenia, and lower initial level of SpO2 at admission are predictors of in-hospital mortality in elderly patients with COVID-19.

8.
Clin Infect Pract ; 13: 100131, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-35005607

RESUMO

Introduction: Asymptomatic COVID-19 patients are the most challenging and feared obstacles in resuming these surgical procedures. The purpose of this study was to evaluate the proportion of asymptomatic carriers detected by RT-PCR in pre-operative orthopaedic evaluation during the peak of the second wave. Methods: 514 asymptomtomatic COVID-19 patients, negative for TOCC (Travel, Profession, Cluster, Contact) risk factors were observed retrospectively. A nasopharyFngeal RT-PCR test was obtained 48 to 72 h before the surgery in all cases. Possible risk factors for a positive test was identified. Results: The detected asymptomatic COVID-19 infection rate during the peak of the second wave among the pre-operative orthopaedic patients was 12.3%. Younger age, female gender, longer duration of admission to RT-PCR test interval were found to be significant (p= < 0.05) risk factors for asymptomatic RT-PCR to be positive. The hazard ratio (HR) for being asymptomatic RT-PCR positive was 4.3 (p = 0. 025), while the RT-PCR was performed at 14 days, but the HR increased to 9.2 (p = 0.049) when the test was performed after 45 days. Conclusion: According to our findings, pre-operative testing to rule out COVID-19 should be regarded as a critical step in preventing the disease clusters in hospitals.

9.
Avian Dis ; 55(2): 230-5, 2011 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-21793438

RESUMO

A total of 38 Newcastle disease virus (NDV) isolates were obtained from 6060 fecal samples from northern pintail (Anas acuta) ducks collected in the Tohoku district in Japan during 2006-09. One isolate from each sampling location and date was selected for a total of 38 isolates, then 15 of these were characterized for their pathogenicity by mean death time of minimum lethal dose (MDT/MLD) using chicken embryos and by plaque formation on chicken embryo fibroblasts. Furthermore, nine isolates were randomly selected from these 15 isolates, and the fusion protein genes were sequenced to characterize amino acid sequences around the cleavage site. All 15 were confirmed to be nonvirulent by MDT/MLD test, and nine isolates were also confirmed as nonvirulent by the cleavage site of the fusion protein 112G/E-K/R-Q-G/E-R*L117 that was specific for nonvirulent NDVs. The characteristics of nine isolates identified by phylogenic analysis of the fusion protein gene indicated that the isolates belong to genotype I or II. In addition, we also isolated 68 avian influenza viruses and 28 other hemagglutinating viruses. Our data indicate that northern pintails are subclinically infected by, perpetuate, and distribute NDV along with different subtypes of avian influenza viruses and other hemagglutinating viruses during their migrations across vast areas over the Northern Hemisphere to Japan.


Assuntos
Doença de Newcastle/virologia , Vírus da Doença de Newcastle/genética , Animais , Patos , Regulação Viral da Expressão Gênica/fisiologia , Japão/epidemiologia , Doença de Newcastle/epidemiologia , Vírus da Doença de Newcastle/patogenicidade , Filogenia , Vigilância da População , Fatores de Tempo , Proteínas Virais de Fusão/genética , Proteínas Virais de Fusão/metabolismo , Virulência
10.
Virus Genes ; 40(1): 94-105, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19916042

RESUMO

Pintails constitute an important host of avian influenza viruses (AIVs). Genetic, molecular, and antigenic characteristics of H5 and H7 AIVs, which we isolated from northern pintails (Anas acuta) wintering in Japan, were analyzed and found to be linked to various ecological features, chiefly in terms of gene geography, as shaped by various migratory aquatic host species. Although all the isolates were found to be of low pathogenicity (LP), we explored gene predispositions that may potentially underlie tentative transition to high pathogenicity (HP). Evolutionarily, the HA and NA genes of the isolates affiliated mostly with Eurasian lineage. The viruses closely related to ours were derived from China, Korea, Mongolia, Japan, and Australia. Comprehensive ecophylogenetic evaluations revealed that the pintail populations we sampled might have given rise to or been involved in the emergence of a LPAI H7N6 subtype that caused outbreaks in quail (Coturnix japonica) farms in Japan, as well as of the first H5N9 subtype ever isolated in Asia. The latter strain isolated by us showed, yet, notable affinity to certain North American and Australian strains, thereby signifying apparent intercontinental interfaces accounted for by extensive water-bird flyways. Noticeable conservation of certain antigenic sites within both Eurasian and North American H7 HAs is apparently an outcome of their advantageous survival value, in terms of restricted immunogenicity. Besides, the Japanese-Korean-Siberian regional axis seems to be particularly important for ongoing generation of novel viral strains due to conveyance of certain genes and genomes by migratory ducks, including such that circulate among pigs and human.


Assuntos
Patos , Genoma Viral , Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Vírus da Influenza A/genética , Influenza Aviária/virologia , Neuraminidase/genética , Sequência de Aminoácidos , Animais , Antígenos Virais/química , Antígenos Virais/imunologia , Genética Populacional , Glicoproteínas de Hemaglutininação de Vírus da Influenza/química , Glicoproteínas de Hemaglutininação de Vírus da Influenza/imunologia , Vírus da Influenza A/imunologia , Vírus da Influenza A/isolamento & purificação , Vírus da Influenza A/metabolismo , Influenza Aviária/imunologia , Japão , Neuraminidase/metabolismo , Filogenia
11.
Virus Res ; 143(1): 44-52, 2009 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-19463720

RESUMO

Since wild ducks constitute a vital element in the epizootiology of avian influenza viruses (AIVs) as well as avian paramyxoviruses (APMVs) and play a key role in the ecology and inter-species transmission of these viruses, it is crucial to elucidate the diversity and prevalence of these viruses within these bird populations. This report shows the presence, antigenic diversity, and inter-annual prevalence variations of AIVs in apparently healthy northern pintail (Anas acta) wintering in Japan. We also provide evidence that this host carries APMV-1: Newcastle disease virus (NDV) and other haemagglutinating viruses. Composite samples (n=2381) of fresh fecal materials were collected from northern pintail during November 2007-March 2008 at different locations of Tohoku district, main Island, Japan. We isolated 47 haemagglutinating viruses, out of which 25 were identified as AIVs, representing 9 combinations of 5 different haemagglutinin (HA) and 6 neuraminidase (NA) subtypes. Both H5 and H7 subtypes were identified and found to be low pathogenic. A further 11 viruses were grouped into APMV-1 (NDV). The rest of the viruses (n=11) remained to be identified. Some of the HA subtypes and NA subtypes detected during the first season reoccurred in the second season, as well as some of their combinations; yet, several new subtypes and combinations appeared during the second season. These findings indicate that different subtypes of AIVs, NDV and other haemagglutinating viruses circulate subclinically in the pintail populations sampled. Pintails should be regarded, potentially, as important spreaders of AIVs and NDVs, particularly due to their extensively ramified flyways, which include various inter-continental routes.


Assuntos
Vírus da Influenza A/isolamento & purificação , Influenza Aviária , Doença de Newcastle , Vírus da Doença de Newcastle/isolamento & purificação , Animais , Variação Antigênica , Patos , Fezes/virologia , Glicoproteínas de Hemaglutininação de Vírus da Influenza/análise , Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Vírus da Influenza A/genética , Vírus da Influenza A/patogenicidade , Influenza Aviária/epidemiologia , Influenza Aviária/virologia , Japão , Doença de Newcastle/epidemiologia , Doença de Newcastle/virologia , Vírus da Doença de Newcastle/genética , Vírus da Doença de Newcastle/patogenicidade , Prevalência , RNA Viral/análise , RNA Viral/genética , Estações do Ano , Análise de Sequência de DNA , Virulência
12.
Bioorg Med Chem Lett ; 19(6): 1632-5, 2009 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-19231178

RESUMO

The purinoceptor subtypes P2X(3) and P2X(2/3) have been shown to play a pivotal role in models of various pain conditions. Identification of a potent and selective dual P2X(3)/P2X(2/3) diaminopyrimidine antagonist RO-4 prompted subsequent optimization of the template. This paper describes the SAR and optimization of the diaminopyrimidine ring and particularly the substitution of the 2-amino group. The discovery of the highly potent and drug-like dual P2X(3)/P2X(2/3) antagonist RO-51 is presented.


Assuntos
Analgésicos/síntese química , Analgésicos/farmacologia , Química Farmacêutica/métodos , Dor/tratamento farmacológico , Antagonistas do Receptor Purinérgico P2 , Pirimidinas/síntese química , Pirimidinas/farmacologia , Trifosfato de Adenosina/química , Animais , Células CHO , Cricetinae , Cricetulus , Desenho de Fármacos , Avaliação Pré-Clínica de Medicamentos , Humanos , Concentração Inibidora 50 , Modelos Químicos , Receptores Purinérgicos P2/química , Relação Estrutura-Atividade
13.
Bioorg Med Chem Lett ; 19(6): 1628-31, 2009 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-19231180

RESUMO

P2X purinoceptors are ligand-gated ion channels whose endogenous ligand is ATP. Both the P2X(3) and P2X(2/3) receptor subtypes have been shown to play an important role in the regulation of sensory function and dual P2X(3)/P2X(2/3) antagonists offer significant potential for the treatment of pain. A high-throughput screen of the Roche compound collection resulted in the identification of a novel series of diaminopyrimidines; subsequent optimization resulted in the discovery of RO-4, a potent, selective and drug-like dual P2X(3)/P2X(2/3) antagonist.


Assuntos
Analgésicos/síntese química , Analgésicos/farmacologia , Química Farmacêutica/métodos , Dor/tratamento farmacológico , Antagonistas do Receptor Purinérgico P2 , Pirimidinas/síntese química , Pirimidinas/farmacologia , Trifosfato de Adenosina/química , Desenho de Fármacos , Avaliação Pré-Clínica de Medicamentos , Humanos , Concentração Inibidora 50 , Íons , Ligantes , Modelos Químicos , Receptores Purinérgicos P2/química , Relação Estrutura-Atividade
14.
Avian Dis ; 53(1): 34-8, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19432001

RESUMO

Ceramic powder prepared by sintering of chicken feces, when mixed with avian influenza viruses or an avian adenovirus, inactivated these organisms to below detection levels. When the ceramic powder was mixed with double-distilled water, the pH of the water rose to 10 but the aqueous phase did not show any antivirus activity. After 10 washings with water or five washings with 1M Tris-HCl (pH 8.0), the ceramic powder still retained antivirus activity. Antivirus activity was not affected by the presence of organic material (33% fetal calf serum). When chicks were fed food containing 5% ceramic powder, there was no difference in body weight between normal feeding and the ceramic-mixture feeding. The mode of action of the ceramic powder remains unknown, but it possibly works by adsorbing the virus. These results show that the ceramic powder has antiviral activities and is a potentially useful tool against avian influenza on poultry farms.


Assuntos
Cerâmica/química , Galinhas , Fezes/química , Animais , Aviadenovirus/fisiologia , Incineração , Vírus da Influenza A/fisiologia , Microscopia Eletrônica de Varredura , Inativação de Vírus
15.
Polymers (Basel) ; 11(11)2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31683959

RESUMO

Meta-aramid fibrids (MAF) have attracted much attention. However, it is difficult for this high mechanical performance fiber to form sufficient interface adhesion between the MAF and polyurethane (PU) matrix due to the chemical inertness of its surface. Thus, the surface activity of MAF should be improved to obtain a high-performance MAF/PU composite. A novel methodology to modify the surface of MAF with a sodium dichloroisocyanurate solution (DCCNa) was developed to obtain chlorinated MAF (MAFC) in this study. A series of MAFC/PU composites was prepared by in situ polymerization processes. The results of Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) demonstrated that the chlorine-contained chemical groups were introduced onto the MAF surfaces after chlorination. Dynamic contact angle analysis (DCAA) revealed that the surface wettability and the surface free energy of the MAFC were significantly improved, which allowed for strong chemical bonding to PU. Scanning electron microscopy (SEM) showed a uniform distribution of MAFC and good interfacing bonding between the MAFC and PU. With the incorporation of 1.5 wt% MAFC into the polyurethane matrix, the tensile and tear strength values of MAFC/PU were 36.4 MPa and 80.1 kN·m-1 respectively, corresponding to improvements of approximately 43.3% and 21.1%, as compared to those of virgin PU as 25.4 MPa and 66.1 kN·m-1, respectively.

16.
Materials (Basel) ; 12(1)2019 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-30621056

RESUMO

Rigid biological systems are increasingly becoming a source of inspiration for the fabrication of the advanced functional materials due to their diverse hierarchical structures and remarkable engineering properties. As a bionic biomaterial with a clear layered structure, excellent mechanical properties, and interesting rainbow colors, nacre has become one of the most attractive models for novel artificial materials design. In this research paper, the tough and strong nacre-like bio-hybrid membranes with an interpenetrating petals structure were fabricated from chitosan (CS) and magadiite (MAG) clay nanosheets through the gel-casting self-assembling method. The analyses from X-ray diffraction (XRD), scanning electron microscope (SEM), and observations of water droplets on membranes indicated that the nacre-like hybrid membranes had a layered compact structure. Fourier transforms infrared spectroscopy (FTIR) analyses suggested that the CS molecular chains formed chemical bonds and hydrogen bonds with MAG layers. The inter-penetrating petal layered structure had a good effect on the mechanical properties of a nacre-like bio-hybrid membranes and the tensile strength of the hybrid membranes could reach at 78.6 MPa. However, the transmission analyses of the results showed that the hybrid membranes still had a certain visible light transmittance. Finally, the hybrid membranes possessed an intriguing efficient fire-shielding property during exposure to the flame of alcohol burner. Consequently, the great biocompatibility and excellent mechanical properties of the bio-hybrid membranes with the special interpenetrating petals structure provides a great opportunity for these composites to be widely applied in biomaterial research.

17.
Eur J Pharm Sci ; 130: 44-53, 2019 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-30660800

RESUMO

The magadiite (MAG) was modified by cetyltrimethyl ammonium-Bromide (CTAB) and then further modified by Chitosan (CS) which is called organic modified-magadiite as magadiite-cetyltrimethyl ammonium bromide (MAG-CTAB) and magadiite-cetyltrimethyl ammonium bromide-Chitosan (MAG-CTAB-CS), respectively, in this research study. The MAG, MAG-CTAB, and MAG-CTAB-CS were used as 5-Fluorouracil (5-FU) drug carrier materials; the drug carrier's materials were marked as magadiite-5-Fluorouracil (MAG/5-FU), magadiite-cetyltrimethyl ammonium bromide-5-Fluorouracil (MAG-CTAB/5-FU), and magadiite-cetyltrimethyl ammonium bromide-Chitosan (MAG-CTAB-CS/5-FU). X-ray diffraction(XRD, Flourier transform infrared spectrometry (FTIR) and scanning electron microscopy (SEM) results were shown that 5-Fluorouracil was combined with carrier materials through physical apparent adsorption, ion exchange, chemical bond, hydrogen bond, and electrostatic interaction. The drug carriers in vitro release behavior in simulated gastric fluids (SGF,pH = 1.35) and intestinal fluids (SIF,pH = 7.40) were investigated. The drug loading capacity and accumulated release ration were as follows the order: MAG-CTAB-CS/5-FU > MAG-CTAB/5-FU > MAG/5-FU. The drug loading capacity of MAG-CTAB-CS/5-FU was 162.29 mg/g, 48 h later the drug accumulated release ratio was 61.24%, and the release amount was 97.52 mg/g for 24 h. Korsmeyer-Peppas model and First order model were found to be suitable to describe the vitro release behavior of 5-Fluorouracil. This would be an economically viable and efficient method for the preparation of advanced drug delivery system.


Assuntos
Antimetabólitos Antineoplásicos/farmacocinética , Portadores de Fármacos/farmacocinética , Liberação Controlada de Fármacos , Fluoruracila/farmacocinética , Silicatos/farmacocinética , Antimetabólitos Antineoplásicos/química , Portadores de Fármacos/química , Fluoruracila/química , Silicatos/química , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Difração de Raios X/métodos
18.
Polymers (Basel) ; 11(9)2019 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-31443463

RESUMO

The layered hydrated sodium salt-magadiite (MAG), which has special interpenetrating petals structure, was used as a functional filler to slowly self-assemble with sodium carboxy-methylcellulose (CMC), in order to prepare nacre-like nanocomposite film by solvent evaporation method. The structure of prepared nacre-like nanocomposite film was characterized by Scanning Electron Microscope (SEM) and X-ray diffraction (XRD) analysis; whereas, it was indicated that CMC macromolecules were inserted between the layers of MAG to increase the layer spacing of MAG by forming an interpenetrating petals structure; in the meantime, the addition of MAG improved the thermal stability of CMC. The tensile strength of CMC/MAG was significantly improved compared with pure CMC. The tensile strength of CMC/MAG reached the maximum value at 1.71 MPa when the MAG content was 20%, to maintaining high transparency. Due to the high content of inorganic filler, the flame retarding performance and the thermal stability were also brilliant; hence, the great biocompatibility and excellent mechanical properties of the bionic nanocomposite films with the unique interpenetrating petals structure provided a great probability for these original composites to be widely applied in material research, such as tissue engineering in biomedical research.

19.
Polymers (Basel) ; 11(4)2019 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-30960591

RESUMO

The magadiite⁻magnetite (MAG⁻Fe3O4) nanocomposite has great potential applications in the field of biomaterials research. It has been used as a novel magnetic sorbent, prepared by co-precipitation method. It has the dual advantage of having the magnetism of Fe3O4 and the high adsorption capacity of pure magadiite (MAG). MAG⁻Fe3O4 was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and vibrating sample magnetometer (VSM). The results showed that Fe3O4 nanoparticles were deposited on the interlayer and surface of magadiite. MAG⁻Fe3O4 was treated as an adsorbent for methylene blue (MB) removal from aqueous solutions. The adsorption properties of MAG⁻Fe3O4 were investigated on methylene blue; however, the results showed that the adsorption performance of MAG⁻Fe3O4 improved remarkably compared with MA and Fe3O4. The adsorption capacity of MAG⁻Fe3O4 and the removal ratio of methylene blue were 93.7 mg/g and 96.2%, respectively (at 25 °C for 60 min, pH = 7, methylene blue solution of 100 mg/L, and the adsorbent dosage 1 g/L). In this research, the adsorption experimental data were fitted and well described using a pseudo-second-order kinetic model and a Langmuir adsorption isotherm model. The research results further showed that the adsorption performance of MAG⁻Fe3O4 was better than that of MAG and Fe3O4. Moreover, the adsorption behavior of MB on MAG⁻Fe3O4 was investigated to fit well in the pseudo-second-order kinetic model with the adsorption kinetics. The authors also concluded that the isothermal adsorption was followed by the Langmuir adsorption isotherm model; however, it was found that the adsorption of the MAG⁻Fe3O4 nanocomposite was a monolayer adsorption.

20.
Avian Dis ; 52(1): 49-53, 2008 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-18459295

RESUMO

Among winter migratory waterfowl, Northern pintails (Anas acuta), in one of the largest flocks in Tohoku district, northeast Japan, were surveyed for influenza A viruses at five wintering sites in three prefectures, viz., Aomori, Akita, and Miyagi. A total of 38 influenza A viruses were isolated from 2066 fecal samples collected during November 2006 through March 2007. The overall isolation rate was 1.84%. Eleven different subtypes were isolated, including nine H5N2, seven H6N8, seven H10N1, four H4N6, three H6N1, three H11N9, and one each of H1N1, H6N2, H6N5, H10N9, H11N1. Only the H4N6 subtype was detected during two successive months, November and December, from Lake Ogawara of Aomori prefecture. One wintering site, Lake Izunuma of Miyagi prefecture, was negative for virus isolation throughout the study period. During the sampling period, the highest virus isolation rate was in December (4.90%) followed by November (2.18%), January (0.91%), and February (0.30%). Virus isolation was negative for samples collected in March 2007. These results suggest that influenza viruses are introduced by Northern pintail when they migrate into Japan, but the viruses are not maintained in the flocks, most likely because the birds are not breeding during the winter. We believe that this relatively large data set creates a strong foundation for future studies of avian influenza virus (AIV) prevalence, evolution, and ecology in wintering sites, along with the role of Northern pintails in the spread of AIV during their migration from northern Russia and Asia to Japan.


Assuntos
Patos/virologia , Vírus da Influenza A/isolamento & purificação , Influenza Aviária/virologia , Migração Animal , Animais , Testes de Hemaglutinação/veterinária , Hemaglutininas/genética , Vírus da Influenza A/classificação , Influenza Aviária/epidemiologia , Japão/epidemiologia , Vigilância da População , Reação em Cadeia da Polimerase Via Transcriptase Reversa/veterinária , Estações do Ano
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