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1.
Int J Mol Sci ; 22(4)2021 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-33572312

RESUMO

Herein, we prepared a series of nanocomposite membranes based on chitosan (CS) and three compositionally and structurally different N-doped graphene derivatives. Two-dimensional (2D) and quasi 1D N-doped reduced graphene oxides (N-rGO) and nanoribbons (N-rGONRs), as well as 3D porous N-doped graphitic polyenaminone particles (N-pEAO), were synthesized and characterized fully to confirm their graphitic structure, morphology, and nitrogen (pyridinic, pyrrolic, and quaternary or graphitic) group contents. The largest (0.07%) loading of N-doped graphene derivatives impacted the morphology of the CS membrane significantly, reducing the crystallinity, tensile properties, and the KOH uptake, and increasing (by almost 10-fold) the ethanol permeability. Within direct alkaline ethanol test cells, it was found that CS/N rGONRs (0.07 %) membrane (Pmax. = 3.7 mWcm-2) outperformed the pristine CS membrane significantly (Pmax. = 2.2 mWcm-2), suggesting the potential of the newly proposed membranes for application in direct ethanol fuel cells.


Assuntos
Fontes de Energia Elétrica , Etanol/química , Grafite/química , Nanocompostos/química , Álcalis/química , Quitosana/química , Estudos de Viabilidade , Nanotubos de Carbono/química , Nitrogênio/química , Oxirredução
2.
Polymers (Basel) ; 15(5)2023 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-36904390

RESUMO

In this work, fully polysaccharide based membranes were presented as self-standing, solid polyelectrolytes for application in anion exchange membrane fuel cells (AEMFCs). For this purpose, cellulose nanofibrils (CNFs) were modified successfully with an organosilane reagent, resulting in quaternized CNFs (CNF (D)), as shown by Fourier Transform Infrared Spectroscopy (FTIR), Carbon-13 (C13) nuclear magnetic resonance (13C NMR), Thermogravimetric Analysis (TGA)/Differential Scanning Calorimetry (DSC), and ζ-potential measurements. Both the neat (CNF) and CNF(D) particles were incorporated in situ into the chitosan (CS) membrane during the solvent casting process, resulting in composite membranes that were studied extensively for morphology, potassium hydroxide (KOH) uptake and swelling ratio, ethanol (EtOH) permeability, mechanical properties, ionic conductivity, and cell performance. The results showed higher Young's modulus (119%), tensile strength (91%), ion exchange capacity (177%), and ionic conductivity (33%) of the CS-based membranes compared to the commercial Fumatech membrane. The addition of CNF filler improved the thermal stability of the CS membranes and reduced the overall mass loss. The CNF (D) filler provided the lowest (4.23 × 10-5 cm2 s-1) EtOH permeability of the respective membrane, which is in the same range as that of the commercial membrane (3.47 × 10-5 cm2s-1). The most significant improvement (~78%) in power density at 80 °C was observed for the CS membrane with neat CNF compared to the commercial Fumatech membrane (62.4 mW cm-2 vs. 35.1 mW cm-2). Fuel cell tests showed that all CS-based anion exchange membranes (AEMs) exhibited higher maximum power densities than the commercial AEMs at 25 °C and 60 °C with humidified or non-humidified oxygen, demonstrating their potential for low-temperature direct ethanol fuel cell (DEFC) applications.

3.
Materials (Basel) ; 15(12)2022 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-35744361

RESUMO

Sedimentation is a naturally occurring process of allowing particles in water bodies to settle out of the suspension under a gravity effect. In this study, the sediments of the Drava River were fully investigated to determine the heavy metal concentrations along the river and their potential reuse in the construction sector. Naturally dehydrated sediments from the Drava River were tested as an additive for the production of fired bricks. The dredged sediments were used as a substitute for natural brick clay in amounts up to 50% by weight, and it was confirmed that up to 20% by weight of the added sediment could be used directly in the process without critically affecting performance. Finally, the naturally dehydrated sediments were also evaluated for their use as a filling material in the construction of levees. The natural moisture content of the dehydrated sediment was too high for it to be used without additives, so quicklime was added as an inorganic binder. The test results showed an improvement in the geotechnical properties of the material to such an extent that it is suitable as a filling material for levees.

4.
Carbohydr Polym ; 251: 117126, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33142658

RESUMO

The use of biomass to produce value-adding materials is a core objective of the circular economy, which has attracted great research interest in recent decades. In this context, we present here a simple dispersion-casting process for consolidation of cellulose nanofibrils (CNF), lignosulphonate (LS)-rich bio-waste and CaCl2 in composite membranes. The addition of CaCl2 to CNF and LS dispersions reduces the ζ potential, due to an electrostatic screening, which promotes the aggregation of CNF, increases its moisture content and promotes LS deposition on CNFs already in the dispersion phase. Addition of both the LS and CaCl2 to CNF dispersion has an adverse effect on the mechanical properties of the final membranes. The effectiveness of the new composite membranes has been described in terms of their passive (charring) flame retardancy and 100 % UVA/UVB shielding capacity, both identified for membranes with the highest LS content, as well as high electronic resistance.


Assuntos
Celulose/química , Retardadores de Chama/análise , Lignina/análogos & derivados , Nanofibras/química , Protetores contra Radiação/química , Lignina/química , Raios Ultravioleta
5.
Appl Microbiol Biotechnol ; 85(3): 563-71, 2010 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-19662398

RESUMO

Conventional vat dyeing involves chemical reduction of dyes into their water-soluble leuco form generating considerable amounts of toxic chemicals in effluents. In the present study, a new beta-nicotinamide adenine dinucleotide disodium salt (NADH)-dependent reductase isolated from Bacillus subtilis was used to reduce the redox dyes CI Acid Blue 74, CI Natural Orange 6, and CI Vat Blue 1 into their water-soluble leuco form. Enzymatic reduction was optimized in relation to pH and temperature conditions. The reductase was able to reduce Acid Blue 74 and Natural Orange 6 in the presence of the stoichiometrically consumed cofactor NADH; meanwhile, Vat Blue 1 required the presence of mediator 1,8-dihydroxyanthraquinone. Oxygen from air was used to reoxidize the dyes into their initial forms. The enzymatic reduction of the dyes was studied and the kinetic constants determined, and these were compared to the chemically-reduced leuco form. The enzyme responsible for the reduction showed homology to a NADH-dependent reductase from B. subtilis based on results from the MS/MS peptide mass mapping of the tryptically digested protein. Additionally, the reduction of Acid Blue 74 to its leuco form by reductase from B. subtilis was confirmed using NADH regenerated by the oxidation of formic acid with formate dehydrogenase from Candida boidinii in the same solution.


Assuntos
Bacillus subtilis/enzimologia , Proteínas de Bactérias/metabolismo , Coenzimas/metabolismo , Corantes/metabolismo , NAD/metabolismo , Oxirredutases/metabolismo , Candida/enzimologia , Formiato Desidrogenases/isolamento & purificação , Formiato Desidrogenases/metabolismo , Concentração de Íons de Hidrogênio , Oxirredução , Oxirredutases/isolamento & purificação , Temperatura
6.
Med Sci Monit ; 15(10): BR293-300, 2009 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-19789506

RESUMO

BACKGROUND: Multiple blood sampling in rat pharmacokinetic (PK) and toxicokinetic studies can result in a pathophysiological response and misleading data interpretation. This study investigated whether these drawbacks can be minimized by replacing withdrawn blood with saline, gelofusine, or donor blood. MATERIAL/METHODS: Rats with cannulated jugular veins were subjected to 12 withdrawals of 250 and 500 microl of blood followed by replacement with the same amount of saline, gelofusine, or donor blood. Red blood cell, hematocrit, hemoglobin, total protein, albumin, glucose, Na, and Cl levels were determined in the drawn blood. RESULTS: Multiple blood sampling caused a time-dependent decrease in red blood cell counts and hematocrit, hemoglobin, total protein, and albumin levels in all the treatment groups, but these effects were significantly alleviated in the blood-treated group. Withdrawal of 500 microl of blood caused more pronounced changes than 250 microl blood withdrawal in the saline- and gelofusine-treatment groups, but not in the blood-treatment group. Plasma glucose and Na remained unchanged in all the treatment groups, while slight changes in Cl levels were observed in the saline- and gelofusine-treatment groups. CONCLUSIONS: Blood sample volume had a crucial impact on the measured parameters, which were least affected in the donor blood-treated group. Regardless of the treatment, up to five 250 microl blood samples can be drawn without causing significant changes in a rat's normal condition. However, for a proper determination of PK profile, more than five blood samples are required and therefore drawn blood should be replaced, preferably with donor blood.


Assuntos
Fenômenos Fisiológicos Sanguíneos/efeitos dos fármacos , Coleta de Amostras Sanguíneas/métodos , Transfusão de Sangue , Poligelina/farmacologia , Cloreto de Sódio/farmacologia , Animais , Glicemia/efeitos dos fármacos , Cloretos/sangue , Contagem de Eritrócitos , Hematócrito , Hemoglobinas/metabolismo , Masculino , Ratos , Ratos Wistar , Sódio/sangue , Fatores de Tempo
7.
Colloids Surf B Biointerfaces ; 181: 561-566, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31185448

RESUMO

This work describes the derivatization of dextran using N-(tert-butyloxycarbonyl)-S-(trityl)-L-cysteine in the presence of N,N'-carbonyldiimidazole (CDI) as a coupling agent. Homogeneous reactions in dimethyl sulfoxide allowed for an efficient coupling of the amino acid derivative to the polymer backbone. Derivatization was confirmed by infrared and 13C NMR spectroscopy, size exclusion chromatography and elemental analysis. The presence of hydrophobic protecting groups resulted in a product that can be shaped into water-insoluble particles stable in an aqueous environment and non-toxic for lung epithelial cells. It is suggested that materials composed of ester bonds between amino acids and polysaccharides are useful for targeted drug delivery, bio-imaging or surface functionalization.


Assuntos
Aminoácidos/química , Cisteína/análogos & derivados , Ésteres/química , Cisteína/química , Dextranos/química , Tamanho da Partícula , Propriedades de Superfície
8.
Pathophysiol Haemost Thromb ; 36(2): 58-63, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-19127083

RESUMO

The objective of our study was to investigate the prevalence of the polymorphisms factor V Leiden (FVL), prothrombin G20210A (PT G20210A), methylenetetrahydrofolate reductase C677T (MTHFR C677T), plasminogen activator inhibitor type 1 -675 4G/5G (PAI-1 4G/5G) and factor XII -4 C/T (FXII -4 C/T) in 295 Slovenian patients with venous thrombosis (VT) and 223 healthy controls in order to establish their contribution to the risk for VT. The major genetic risk factor was FVL, while PT G20210A, MTHFR 677 C/T, PAI-1 4G/5G and FXII -4 C/T polymorphisms were not. However, PT G20210A increased the risk of recurrent VT, MTHFR C677T increased the risk in older patients, while the FXII -4 T allele suggested a possible protective effect in younger patients. The risk of VT increased with increasing number of genetic defects.


Assuntos
Trombofilia/genética , Trombose Venosa/genética , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Estudos de Casos e Controles , Fator V , Fator XII , Feminino , Predisposição Genética para Doença , Genótipo , Humanos , Masculino , Metilenotetra-Hidrofolato Redutase (NADPH2) , Pessoa de Meia-Idade , Mutação , Inibidor 1 de Ativador de Plasminogênio , Polimorfismo de Nucleotídeo Único , Protrombina , Recidiva , Risco , Eslovênia/epidemiologia , Adulto Jovem
9.
Clin Appl Thromb Hemost ; 14(1): 55-62, 2008 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-17895509

RESUMO

Thrombophilia is considered to increase the risk of venous thrombosis (VT) due to hemostasis activation. To determine the level of hemostasis activation in thrombophilic subjects with or without a history of VT, hemostasis activation markers prothrombin fragment 1 and 2 (F1+2), thrombin-antithrombin complex (TAT), and cross-linked fibrin degradation products (D-dimer) were measured in 94 subjects with (patients) and 101 subjects without a history of VT (controls). A total of 34.8% of patients and 14.8% of controls (P= .002) had at least 1 thrombophilic defect (protein C deficiency, activated protein C [APC] resistance, presence of lupus anticoagulants, or prothrombin G20210A polymorphism). The subjects were divided into 4 subgroups: patients with (TF(+) patients) and without (TF(-) patients) thrombophilia, and controls with (TF(+) controls) and without (TF(-) controls) thrombophilia. Hemostasis activation was comparable between all patients and controls (TAT: 2.1 vs 2.6 microg/L; F1+2: 1.0 vs 0.9 nmol/L; D-dimer: 36 vs 37 microg/L, respectively) and between TF(+) and TF(- ) patients. However, TF(+) controls had a significantly higher prevalence of increased hemostasis activation markers compared with TF(-) controls (TAT>4.4 microg/L, 38.4 vs 7.3%; F1+2>1.1 nmol/L, 53.8 vs 22.0%; D-dimer >78 microg/L, 30.7 vs 8.8% of subjects, respectively; all P< .05). After stratification for thrombophilic defects, hemostasis activation was associated with APC resistance in controls and with protein C deficiency in patients. To conclude, thrombophilia was associated with hemostasis activation in controls. We assumed that, in patients, the differences in hemostasis activation between subjects with or without thrombophilia were blurred due to undetermined and unidentified thrombophilic defects.


Assuntos
Hemostasia , Trombofilia/sangue , Trombose Venosa/sangue , Adulto , Idoso , Idoso de 80 Anos ou mais , Biomarcadores/sangue , Estudos de Casos e Controles , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Deficiência de Proteína C
10.
Thromb Res ; 120(1): 39-46, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17034835

RESUMO

INTRODUCTION: Young subjects with acute cerebral ischaemia - stroke or transient ischaemic attack - form an etiologically heterogeneous and often not clearly explained group of patients. The aim was to investigate possible disturbances in haemostasis and inflammation long after an acute cerebral ischaemic event. MATERIALS AND METHODS: Forty-four consecutive patients referred after having suffered from acute cerebral ischaemia before the age of 45 participated 1 to 9 years (median value 5 years) after the event. At the time of blood sampling 33 (75%) patients were receiving antithrombotic treatment. Forty-six apparently healthy subjects of the same age group served as controls. In all subjects global haemostasis parameters (overall haemostasis, coagulation and fibrinolytic potential), thrombophilia, several markers of haemostasis activation and inflammation were determined. RESULTS: Patients did not differ from controls in most of the conventional risk factors and the presence of most forms of thrombophilia, although in seven (17.5%) patients the weak presence of lupus anticoagulants was observed. Patients had significantly increased overall haemostasis and coagulation potential, increased soluble P-selectin and D-dimer, decreased overall fibrinolysis potential and increased fibrinogen and C-reactive protein compared to controls. The subgroups of patients receiving antiplatelet treatment, with thrombophilia and recurrent acute cerebral ischaemia, did not differ significantly from the other patients. CONCLUSIONS: In young patients long after acute cerebral ischaemia an imbalance in the haemostatic system and a minor, but significant degree of inflammation was detected. The mechanisms behind haemostatic imbalance seem to be enhanced thrombin generation, platelet activation and depressed fibrinolysis.


Assuntos
Transtornos da Coagulação Sanguínea/sangue , Isquemia Encefálica/sangue , Mediadores da Inflamação/sangue , Inflamação/sangue , Doença Aguda , Adulto , Transtornos da Coagulação Sanguínea/complicações , Testes de Coagulação Sanguínea , Isquemia Encefálica/etiologia , Estudos de Casos e Controles , Feminino , Hemostasia , Humanos , Inflamação/complicações , Ataque Isquêmico Transitório/sangue , Ataque Isquêmico Transitório/etiologia , Masculino , Pessoa de Meia-Idade , Acidente Vascular Cerebral/sangue , Acidente Vascular Cerebral/etiologia , Fatores de Tempo
11.
J Colloid Interface Sci ; 465: 93-105, 2016 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-26669495

RESUMO

Fusing multiwall carbon nanotubes (MWCNTs) with TiO2 at the nano-scale level promotes the separation of those electron-hole charges generated upon UV and daylight irradiation. In this study, we investigated facile sonochemical synthesis, combined with the calcination process for the preparations of TiO2-MWCNT composites with different mole ratios of titanium and carbon. In order to produce stable nano dispersions we exploited an innovative biotechnology-based approach for the covalent functionalizations of TiO2-MWCNTs with in-situ synthesized soluble phenoxazine dye molecules. The none and functionalized TiO2-MWCNTs composites were analyzed by a range of analytical techniques including XRD, Raman, XPS, SEM and UV-vis diffuse reflectance spectroscopy (DRS), and dynamic light scattering (DLS). The photocatalytic activity was evaluated toward the liquid-phase degradation of MB in aqueous solution under both UV and visible light irradiation. TiO2-MWCNTs with optimized mole ratio exhibit much higher photocatalytic activity and stability than bare TiO2. The as-prepared TiO2-MWCNTs photocatalyst possessed good adsorptivity of dyes, extended light absorption range and efficient charge separation properties simultaneously. The results indicated that the soluble phenoxazine dyes and amino-benzenesulfonic acid monomers were covalently grafted on to the surfaces of TiO2-MCNTs, which promoted good aquatic dispersibility and extended light absorption, resulting in increased photocatalytic efficiency.

12.
Biomed Mater ; 11(4): 045015, 2016 08 10.
Artigo em Inglês | MEDLINE | ID: mdl-27509486

RESUMO

Hydrogels offer several advantages as biomaterials for bone regeneration, including ease of incorporation of soluble substances such as mineralization-promoting enzymes and antibacterial agents. Mineralization with calcium phosphate (CaP) increases bioactivity, while antibacterial activity reduces the risk of infection. Here, gellan gum (GG) hydrogels were enriched with alkaline phosphatase (ALP) and/or Seanol(®), a seaweed extract rich in phlorotannins (brown algae-derived polyphenols), to induce mineralization with CaP and increase antibacterial activity, respectively. The sample groups were unmineralized hydrogels, denoted as GG, GG/ALP, GG/Seanol and GG/Seanol/ALP, and hydrogels incubated in mineralization medium (0.1 M calcium glycerophosphate), denoted as GG/ALP_min, GG/Seanol_min and GG/Seanol/ALP_min. Seanol(®) enhanced mineralization with CaP and also increased compressive modulus. Seanol(®) and ALP interacted in a non-covalent manner. Release of Seanol(®) occurred in a burst phase and was impeded by ALP-mediated mineralization. Groups GG/Seanol and GG/ALP/Seanol exhibited antibacterial activity against methicillin-resistant Staphylococcus aureus. GG/Seanol/ALP_min, but not GG/Seanol_min, retained some antibacterial activity. Eluates taken from groups GG/ALP_min, GG/Seanol_min and GG/ALP/Seanol_min displayed comparable cytotoxicity towards MG-63 osteoblast-like cells. These results suggest that enrichment of hydrogel biomaterials with phlorotannin-rich extracts is a promising strategy to increase mineralizability and antibacterial activity.


Assuntos
Antibacterianos/química , Hidrogéis/química , Polissacarídeos Bacterianos/química , Alga Marinha/química , Taninos/química , Fosfatase Alcalina/metabolismo , Anti-Infecciosos/química , Materiais Biocompatíveis/química , Regeneração Óssea , Fosfatos de Cálcio/química , Linhagem Celular , Humanos , Staphylococcus aureus Resistente à Meticilina , Testes de Sensibilidade Microbiana , Osteoblastos/citologia , Solubilidade , Espectroscopia de Infravermelho com Transformada de Fourier , Estresse Mecânico , Termogravimetria
13.
Thromb Haemost ; 93(3): 437-42, 2005 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-15735792

RESUMO

The antithrombotic potential of new direct thrombin inhibitors built on the azaphenylalanine scaffold (LK-732, LK-639 and LK-731) and their amidoxime prodrugs (LK-658, LK-633 and LK-730) was studied in comparison to argatroban and nadroparin in two rat models of venous thrombosis, induced either by complete stasis combined with hypercoagulability (model 1) or by partial stasis combined with vessel injury (model 2). In initial experiments LK-732 was established as the most promising antithrombotic of the LK inhibitors and as such was further tested. In model 1, intravenous bolus administration of LK-732 produced a dose-dependent inhibition of thrombus formation with an ID50 value of 1.3 mg/kg. This ID50 value was approximately four times higher than the ID50 value of argatroban (0.3 mg/kg; p=0.011). However, in model 2, LK-732 and argatroban decreased thrombus weight by 50% at similar ID50 values (3.8 mg/kg vs 3.0 mg/kg, respectively; p=0.726). The ex vivo anticoagulant effect of LK-732 was substantially weaker compared to argatroban at doses that produced comparable antithrombotic effects. After subcutaneous administration, in vivo thrombus weight reduction of LK inhibitors (10 mg/kg) ranged between 22 to 48%. However, their oral antithrombotic effect at a dose of 30 mg/kg was rather low. LK amidoxime prodrugs failed to produce a substantial antithrombotic effect after subcutaneous (10 mg/kg) as well as after oral administration (30 mg/kg). In conclusion, thrombin inhibitors built on the azaphenylalanine scaffold represent a new group of intravenously effective antithrombotics. However, optimisation of the oral antithrombotic effect of amidoxime prodrug LK-658 of the lead inhibitor LK-732 is required for justifying further development of these inhibitors.


Assuntos
Fibrinolíticos/síntese química , Fenilalanina/análogos & derivados , Trombina/antagonistas & inibidores , Trombose Venosa/tratamento farmacológico , Administração Oral , Animais , Anticoagulantes/administração & dosagem , Anticoagulantes/síntese química , Anticoagulantes/farmacologia , Arginina/análogos & derivados , Testes de Coagulação Sanguínea , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Avaliação Pré-Clínica de Medicamentos , Feminino , Fibrinolíticos/administração & dosagem , Fibrinolíticos/farmacologia , Injeções Subcutâneas , Masculino , Nadroparina/farmacologia , Fenilalanina/administração & dosagem , Fenilalanina/síntese química , Fenilalanina/farmacologia , Ácidos Pipecólicos/farmacologia , Ratos , Ratos Wistar , Relação Estrutura-Atividade , Sulfonamidas , Trombofilia , Veia Cava Inferior/lesões , Trombose Venosa/prevenção & controle
14.
Carbohydr Polym ; 125: 301-13, 2015 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-25857987

RESUMO

Nano-sized cellulose ester derivatives having phosphoryl side groups were synthesised by phosphorylation of nanofibrilated cellulose (NFC) and nanocrystaline cellulose (NCC), using different heterogeneous (in water) and homogeneous (in molten urea) processes with phosphoric acid as phosphoryl donor. The phosphorylation mechanism, efficacy, stability, as well as its influence on the NC crystallinity and thermal properties, were evaluated using ATR-FTIR and (13)C NMR spectroscopies, potentiometric titration, capillary electrophoresis, X-ray diffraction, colorimetry, thermogravimmetry and SEM. Phosphorylation under both processes created dibasic phosphate and monobasic tautomeric phosphite groups at C6 and C3 positioned hydroxyls of cellulose, yielded 60-fold (∼1,173 mmol/kg) and 2-fold (∼1.038 mmol/kg) higher surface charge density for p-NFC and p-NCC, respectively, under homogenous conditions. None of the phosphorylations affected neither the NC crystallinity degree nor the structure, and noticeably preventing the derivatives from weight loss during the pyrolysis process. The p-NC showed high hydrolytic stability to water at all pH mediums. Reusing of the treatment bath was examined after the heterogeneous process.


Assuntos
Celulose/química , Nanopartículas/química , Ácidos Fosfóricos/química , Temperatura Alta , Concentração de Íons de Hidrogênio , Hidrólise , Fosforilação
15.
Carbohydr Polym ; 125: 340-51, 2015 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-25857991

RESUMO

The acetylation efficiency of nanofibrillated cellulose (NFC) with acetic anhydride as acetyl donor was studied using lipase from Aspergillus niger in a mixture of dimethyl sulphoxide (DMSO) and phosphate buffer solution at ambient conditions and in supercritical carbon dioxide (scCO2). The chemical acetylation of NFC with comparable ester content was carried out for comparison. The ATR-FTIR, solid-state CP/MAS (13)C NMR and DSC analyses revealed that, besides the enzyme-catalysed acetylation, predominantly appearing at the C-6 position of cellulose hydroxyls, a strong and stable acyl-enzyme intermediate attachment also occurred on the NFC via Maillard reaction. Enzymatic acetylation via attached acyl-enzyme complex on NFC yielded high hydophobicity (contact angle of 84±9°), whereas the chemical acetylation with comparable ester content resulted in a much lower hydrophobic surface with a contact angle of 33±3°. Finally, the adsorption capacity profiles of lysozyme and BSA proteins on native, chemically and enzymatically acetylated NFC as a function of the pH medium were determined.


Assuntos
Anidridos Acéticos/química , Celulose/análogos & derivados , Lipase/química , Nanofibras/química , Acetilação , Biocatálise , Celulose/síntese química , Celulose/química
16.
J Hazard Mater ; 294: 177-85, 2015 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-25867590

RESUMO

The potential of nanoscaled cellulose and enzymatically phosphorylated derivatives as bio-adsorbents to remove metal ions (Ag(+), Cu(2+) and Fe(3+)) from model water and industrial effluents is demonstrated. Introduction of phosphate groups onto nanocelluloses significantly improved the metal sorption velocity and sorption capacity. The removal efficiency was considered to be driven by the high surface area of these nanomaterials as well as the nature and density of functional groups on the nanocellulose surface. Generally, in the solutions containing only single types of metal ions, the metal ion selectivity was in the order Ag(+)>Cu(2+)>Fe(3+), while in the case of mixtures of ions, the order changed to Ag(+)>Fe(3+)>Cu(2+), irrespective of the surface functionality of the nanocellulose. In the case of industrial effluent from the mirror making industry, 99% removal of Cu(2+) and Fe(3+) by phosphorylated nanocellulose was observed. The study showed that phosphorylated nanocelluloses are highly efficient biomaterials for scavenging multiple metal ions, simultaneously, from industrial effluents.


Assuntos
Celulose/química , Metais Pesados/química , Nanofibras/química , Nanopartículas/química , Poluentes Químicos da Água/química , Adsorção , Hexoquinase/química , Resíduos Industriais , Fosforilação , Eliminação de Resíduos Líquidos/métodos
17.
Carbohydr Polym ; 129: 135-42, 2015 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-26050898

RESUMO

Injectable hydrogels for bone regeneration consisting of chitosan, sodium beta-glycerophosphate (Na-ß-GP) and alkaline phosphatase (ALP) were enriched with the polyphenols phloroglucinol (PG) and gallic acid (GA) and characterized physicochemically and biologically with respect to properties relevant for applications in bone regeneration, namely gelation kinetics, mineralizability, antioxidant properties, antibacterial activity, cytocompatibility and ability to support adhesion and growth of human osteoblast-like MG63 cells. Enrichment with PG and GA had no negative effect on gelation kinetics and mineralizability. PG and GA both enhanced antioxidant activity of unmineralized hydrogels. Mineralization reduced antioxidant activity of hydrogels containing GA. Hydrogels containing GA, PG and without polyphenols reduced colony forming ability of Escherichia coli after 1h, 3h and 6h incubation and slowed E. coli growth in liquid culture for 150min. Hydrogels containing GA were cytotoxic and supported cell growth more poorly than polyphenol-free hydrogels. PG had no negative effect on cell adhesion and growth.


Assuntos
Antibacterianos/farmacologia , Quitosana/farmacologia , Hidrogéis/farmacologia , Minerais/química , Polifenóis/farmacologia , Fosfatase Alcalina/metabolismo , Adesão Celular/efeitos dos fármacos , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Humanos , Cinética , Testes de Sensibilidade Microbiana , Osteoblastos/citologia , Osteoblastos/efeitos dos fármacos , Espectroscopia de Infravermelho com Transformada de Fourier
18.
Thromb Haemost ; 92(5): 1129-35, 2004 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-15543343

RESUMO

The effects of cerivastatin and fenofibrate on proteins involved in haemostasis and on markers of inflammation were investigated in otherwise healthy middle-aged males with combined hyperlipidemia. Besides classical risk factors, other so-called novel risk factors for coronary artery disease are seen to be playing an increasingly important role in the development and progression of atherosclerosis. Thirty-eight males, aged 49 +/-5 years were randomised to 12 weeks treatment either with cerivastatin at a daily dose of 0.2 mg to 0.4 mg to achieve the LDL cholesterol goal of <3.0 mM, or with fenofibrate 250 mg daily. Fasting serum lipids, homocysteine, total and free tissue factor pathway inhibitor (TFPI), plasminogen activator inhibitor (PAI-1) and tissue plasminogen activator (t-PA) antigen and activity, C-reactive protein (CRP), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) were measured. No change in homocysteine level was observed in the cerivastatin group, while after fenofibrate administration it increased (p <0.0001). Total TFPI decreased significantly after cerivastatin (p = 0.002), but not after fenofibrate. Free TFPI did not decrease after either drug. Neither drug affected (t-PA) antigen and activity, while fenofibrate increased PAI-1 antigen (p <0.05) and activity (p <0.05). Cerivastatin decreased serum CRP values by 49.5% (p = 0.001), and fenofibrate by 29.8% (p = 0.03). The decreases of CRP in the two groups differed significantly (p = 0.04). IL-6 levels decreased significantly in the fenofibrate group (39%; p <0.0001), but not in the cerivastatin group (15%; p = 0.24) No significant decreases were observed for TNF-alpha. Cerivastatin had neutral effects on fibrinolysis, homocysteine or coagulation. On the other hand, fenofibrate increased PAI-1 antigen and activity and homocysteine, and did not affect coagulation. Both cerivastatin and fenofibrate reduced CRP levels, the decrease being significantly greater after cerivastatin. Fenofibrate also significantly decreased IL-6.


Assuntos
Inibidores de Hidroximetilglutaril-CoA Redutases/administração & dosagem , Hiperlipidemias/sangue , Hiperlipidemias/tratamento farmacológico , Hipolipemiantes/administração & dosagem , Adulto , Arteriosclerose/etiologia , Arteriosclerose/prevenção & controle , Coagulação Sanguínea/efeitos dos fármacos , Fatores de Coagulação Sanguínea/análise , Peso Corporal , Proteína C-Reativa/análise , Proteína C-Reativa/efeitos dos fármacos , LDL-Colesterol/sangue , Ácido Clofíbrico/administração & dosagem , Ácido Clofíbrico/farmacologia , Citocinas/sangue , Fenofibrato/administração & dosagem , Fenofibrato/farmacologia , Homocisteína/sangue , Humanos , Inibidores de Hidroximetilglutaril-CoA Redutases/farmacologia , Hipolipemiantes/farmacologia , Lipídeos/sangue , Masculino , Pessoa de Meia-Idade , Piridinas/administração & dosagem , Piridinas/farmacologia , Fatores de Risco
19.
Thromb Res ; 108(2-3): 107-14, 2002 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-12590945

RESUMO

Two automated turbidimetric D-dimer assays (BC D-dimer Plus, Dade Behring, Marburg, Germany and Auto-Dimer, Biopool, Umeå, Sweden) were compared to two enzyme-linked immunosorbent assays (ELISAs) (Enzygnost D-dimer micro, Dade Behring and Asserachrome D-dimer, Diagnostica Stago, Asnières, France) and two rapid D-dimer assays (SimpliRed, Agen Biomedical, Brisbane, Australia and Minutex, Biopool) in out-patients with suspected deep vein thrombosis (DVT). In addition, the performance of prothrombin fragment 1+2 (F1+2), thrombin-antithrombin complex (TAT), and soluble adhesion molecules VCAM-1 and P-selectin for DVT diagnosis was assessed. One hundred and thirty-five consecutive out-patients with suspected DVT of the lower limb were included, and in 52 (39%), DVT was confirmed by compression ultrasound. All D-dimer assays investigated reliably excluded DVT in those patients without DVT irrespective of their pre-test clinical probability of DVT. One D-dimer ELISA (Dade Behring) gave the highest area under the receiver operating characteristic (ROC) curve compared to other assays, and therefore, this was the most accurate assay in differentiating patients with from patients without DVT. The diagnostic performance of one automated turbidimetric assay (Auto Dimer, Biopool) was similar to ELISA and its convenience close to rapid latex agglutination assays. Most patients with a high pre-test clinical probability of DVT had positive D-dimer regardless of the presence or absence of DVT, which decreased the specificity of the tests and made D-dimer determination less useful for this group of patients. Because the diagnostic accuracy [sensitivity, specificity, negative (NPV) and positive predictive value (PPV)] of F1+2, TAT, VCAM-1 and P-selectin was inferior to D-dimer assay, these assays could not substitute or supplement D-dimer testing in diagnosis of DVT. Levels of VCAM-1 and P-selectin were increased in patients with DVT and should therefore be investigated further to clarify their role in DVT.


Assuntos
Produtos de Degradação da Fibrina e do Fibrinogênio/metabolismo , Trombose Venosa/sangue , Trombose Venosa/diagnóstico , Adulto , Idoso , Antitrombina III , Biomarcadores/sangue , Ensaio de Imunoadsorção Enzimática , Feminino , Produtos de Degradação da Fibrina e do Fibrinogênio/análise , Hemostasia , Humanos , Masculino , Pessoa de Meia-Idade , Nefelometria e Turbidimetria , Selectina-P/sangue , Fragmentos de Peptídeos/sangue , Peptídeo Hidrolases/sangue , Valor Preditivo dos Testes , Protrombina , Fatores de Risco , Sensibilidade e Especificidade , Molécula 1 de Adesão de Célula Vascular/sangue , Trombose Venosa/etiologia
20.
Thromb Res ; 114(3): 179-84, 2004.
Artigo em Inglês | MEDLINE | ID: mdl-15342214

RESUMO

Leakage of viscous bone cement into venous blood possibly resulting in pulmonary embolism may occur during percutaneous vertebroplasty. Our aim was to study if bone cement surface or cement liquid component could induce platelet aggregation or plasma coagulation in vitro. Two types of commonly used methyl-methacrylate bone cement, Palacos (Heraeus Kulzer, Germany) and Vertebroplastic (DePuy, Acro Med, England), were smeared on thin glass slides that were inserted over the bottom of cuvettes immediately or after 24 h, and platelet aggregation was recorded over 10 min. Bone cement liquid component, containing methyl-methacrylate monomer and N,N-dimethyl-p-toluidine, was tested in 2% and 4% final concentration. Partial thromboplastin time (PTT) was determined by the hook method in the presence of bone cement-smeared glass slides or 6% bone cement liquid. Both types of bone cement, either fresh or aged, did not promote platelet aggregation, whereas collagen-coated glass slides induced substantial platelet aggregation (65 +/- 37%). On the other hand, bone cement liquids reduced platelet aggregation induced by collagen solution to an average of less than 15% (p < 0.01). Bone cement, fresh or aged, had no effect on PTT, but bone cement liquids significantly prolonged PTT: median and 1st-3rd interquartile range 149 (96-171) s for Vertebroplastic and 132 (99-194) s for Palacos, p = 0.03 for both comparisons with normal pool plasma without additives that had PTT of 69 (62-71) s. We conclude that the surface of fresh or aged bone cement is not thrombogenic in vitro. The bone cement liquid inhibits platelet aggregation and plasma clotting in relatively high concentrations that cannot be expected in vivo.


Assuntos
Coagulação Sanguínea/efeitos dos fármacos , Cimentos Ósseos/farmacologia , Teste de Materiais , Metilmetacrilatos/farmacologia , Agregação Plaquetária/efeitos dos fármacos , Células Cultivadas , Relação Dose-Resposta a Droga , Humanos , Metilmetacrilatos/efeitos adversos , Tempo de Tromboplastina Parcial , Trombose/sangue , Trombose/induzido quimicamente , Trombose/diagnóstico
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