Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 19 de 19
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Sci Total Environ ; 922: 171375, 2024 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-38431162

RESUMO

Alkyl glycosides (AGs), commonly used nonionic surfactants, may have toxic effects on the environmental organisms. However, the complex concentration-response patterns of AGs with varying alkyl side chains and their mixtures have not been thoroughly studied. Therefore, the luminescence inhibition toxicities of six AGs with different alkyl side chains, namely, ethyl (AG02), butyl (AG04), hexyl (AG06), octyl (AG08), decyl (AG10), and dodecyl (AG12) glucosides, were determined in Vibrio qinghaiensis sp. -Q67 (Q67) at 0.25, 3, 6, 9, and 12 h. The six AGs exhibited time- and side-chain-dependent nonmonotonic concentration- responses toward Q67. AG02, with a short side chain, presented a concentration-response curve (CRC) with two peaks after 6 h and stimulated the luminescence of Q67 at both 6 and 9 h. AG04, AG06, and AG08 showed S-shaped CRCs at five exposure time points, and their toxicities increased with the side-chain length. AG10 and AG12, with long side chains, exhibited hormesis at 9 and 12 h. Molecular docking was performed to explore the mechanism governing the possible influence of AGs on the luminescence response. The effects of AGs on Q67 could be attributed to multiple luminescence-regulatory proteins, including LuxA, LuxC, LuxD, LuxG, LuxI, and LuxR. Notably, LuxR was identified as the primary binding protein among the six AGs. Given that they may co-exist, binary mixtures of AG10 and AG12 were designed to explore their concentration-response patterns and interactions. The results revealed that all AG10-AG12 binary mixture rays showed time-dependent hormesis on Q67, similar to that shown by their individual components. The interactions of these binary mixtures were mainly characterized by low-concentration additive action and high-concentration synergism at different times.


Assuntos
Glicosídeos , Vibrio , Glicosídeos/toxicidade , Simulação de Acoplamento Molecular , Interações Medicamentosas , Transativadores/farmacologia
2.
Environ Res ; 248: 118418, 2024 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-38316386

RESUMO

There is potential for personal care products (PCPs) components and mixtures to induce hormesis. How hormesis is related to time and transmitted from components to mixtures are not clear. In this paper, we conducted determination of components in 16 PCP products and then ran frequent itemset mining on the component data. Five high-frequency components (HFCs), betaine (BET), 1,3-butanediol (BUT), ethylenediaminetetraacetic acid disodium salt (EDTA), glycerol (GLO), and phenoxyethanol (POE), and 14 mixtures were identified. For each mixture system, one mixture ray with the actual mixture ratios in the products was selected. Time-dependent microplate toxicity analysis was used to test the luminescence inhibition toxicity of five HFCs and 14 mixture rays to Vibrio qinghaiensis sp.-Q67 at 12 concentration gradients and eight exposure times. It is showed that BET, EDTA, POE, and 13 mixture rays containing at least one J-type component showed time-dependent hormesis. Characteristic parameters used to describe hormesis revealed that the absolute value of the maximum stimulatory effect (|Emin|) generally increased with time. Notably, mixtures composed of POE and S-type components showed greater |Emin| than POE alone at the same time. Importantly, the maximum stimulatory effective concentration, NOEC/the zero effective concentration point, and EC50 remained relatively stable. Nine hormesis transmission phenomena were observed in different mixture rays. While all mixtures primarily exhibited additive action, varying degrees of synergism and antagonism were noted in binary mixtures, with no strong synergism or antagonism observed in ternary and quaternary mixtures. These findings offer valuable insights for the screening of HFCs and their mixtures, as well as the study of hormesis transmission in personal care products.


Assuntos
Cosméticos , Vibrio , Hormese , Ácido Edético
3.
Sci Total Environ ; 904: 167204, 2023 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-37741385

RESUMO

Disinfectants and their mixtures can induce hormesis. However, how the mixture hormesis is related to those of components and the interactions in disinfectant mixtures remain unclear. In this paper, the luminescence inhibition toxicities of chlorinated sodium phosphate (CSP), dodecyl dimethyl benzyl ammonium bromide (DOB), dodecyl dimethyl benzyl ammonium chloride (DOC), ethanol (EtOH), glutaraldehyde (GLA), hydrogen peroxide (H2O2), isopropyl alcohol (IPA), n-propanol (NPA), and 20 mixture rays in four mixture systems (EtOH-H2O2, DOB-H2O2, DOC-EtOH, and EtOH-IPA-NPA) containing at least one component showing hormesis to Vibrio qinghaiensis sp.-Q67 (Q67) were determined at 0.25, 3, 6, 9, and 12 h. The synergism-antagonism heatmap based on independent action model (noted as SAHmapIA) was developed to systematically evaluate the interactions in various mixtures. It was shown that five disinfectants (CSP, EtOH, H2O2, NPA, and IPA) and 17 mixture rays exhibited time-dependent hormesis. The hormetic component was responsible for the hormesis of the mixture rays. Most mixture rays showed low- concentration/dose additive action and high-concentration/dose synergism at different time. This study further exemplified the interrelationship between the hormesis in the mixtures and their components and implied the need to pay attention to the time-dependent hormesis and interactions induced by the disinfectants.


Assuntos
Desinfetantes , Vibrio , Hormese , Desinfetantes/toxicidade , Peróxido de Hidrogênio , Interações Medicamentosas
4.
Sci Total Environ ; 904: 166651, 2023 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-37647971

RESUMO

Hormesis is a widely recognized and extensively studied phenomenon. However, few studies have described the quantitative characteristics of hormesis required for appropriate risk assessment. Although skin care product (SCP) mixtures and their active ingredients can induce the hormesis of Vibrio qinghaiensis sp.-Q67 (Q67), the quantitative characteristics of time-dependent hormetic dose responses in SCPs have not yet been investigated. In this study, 28 SCP mixtures were tested for luminescence toxicity against Q67 after five exposure durations (0.25, 3, 6, 9, and 12 h). With increasing exposure duration, the concentration response curves (CRCs) were classified as constant monotonic nonlinear (S-shaped) for four SCPs, S- to hormetic (J-shaped) for 13 SCPs, and constant J-shaped for 11 SCPs. Of 140 CRCs, 98 were J-shaped. An increased frequency of SCPs inducing hormesis was observed. The toxicity (pEC50) of the SCPs was independent of the exposure duration and product type. The maximum stimulatory effect (Emin) of the 12 SCPs increased with exposure duration. We proposed a modified parameter, the width of inhibition dose zone (WIDZ; EC50/EC10), to depict the width of inhibition dose zone. The WIDZ of S-shaped CRCs were significantly larger than that of J-shaped CRCs. In addition, the characteristic parameters reported in the general literature were analyzed. The good linear relationship between EC50 and the maximum stimulatory effective concentration (ECmin) indicated that toxicity may be transformed into stimulatory effects over exposure durations. The width of stimulation dose zone (WSDZ) and Emin of the seven SCPs had the same increasing trends with increasing exposure duration. The combination of WIDZ with other characteristic parameters (e.g., zero effective concentration point, ECmin, etc.) could better depict hormesis with low-dose stimulation and high-dose inhibition. The quantitative characteristics of the dose-responses of hormesis-inducing SCPs could provide reference basis for the risk assessment of SCP mixtures.


Assuntos
Hormese , Vibrio , Luminescência , Higiene da Pele
5.
Sci Total Environ ; 893: 164918, 2023 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-37327899

RESUMO

With the widespread use of pesticides, the coexistence of multiple low-residue pesticides in environmental media has increased significantly, and the "cocktail" effect caused by this phenomenon has garnered increasing attention. However, owing to the scarcity of information regarding the modes of action (MOAs) of chemicals, the application of concentration addition (CA) models for evaluating and predicting the toxicity of mixture with similar MOAs is limited. Additionally, the joint toxicity laws of complex mixture systems to different toxicity endpoints in organisms remain unclear, and effective methods to test the mixture toxicity on lifespan and reproductive inhibition are lacking. Therefore, in this study, the similarity of pesticide MOAs was characterized using molecular electronegativity-distance vector (MEDV-13) descriptors based on eight pesticides (aldicarb, methomyl, imidacloprid, thiamethoxam, dichlorvos, dimethoate, methamidophos and triazophos). Additionally, the methods of lifespan and reproduction inhibition microplate toxicity analysis of elegans (EL-MTA and ER-MTA) were established to test the lifespan and reproduction inhibition toxicity of Caenorhabditis elegans. Finally, a unified scale synergistic-antagonistic heatmap (SAHscale) method was proposed to explore the combined toxicity of the mixtures on the lifespan, reproduction, and mortality of nematodes. The results showed that the MEDV-13 descriptors could effectively characterize the similarity in MOAs. The lifespan and reproductive ability of Caenorhabditis elegans were significantly inhibited when the pesticide exposure concentration was one order of magnitude lower than the lethal dose. The sensitivity of lifespan and reproductive endpoints to mixtures was dependent on the concentration ratio. The same rays in the mixture had consistent toxicity interactions on the lifespan and reproductive endpoints of Caenorhabditis elegans. In conclusion, we demonstrated the feasibility of MEDV-13 in characterizing the similarity of MOAs, and provided a theoretical basis for exploring the mechanism of chemical mixtures by studying their apparent toxicity of mixtures on nematode lifespan and reproduction endpoints.


Assuntos
Nematoides , Praguicidas , Animais , Caenorhabditis elegans , Praguicidas/toxicidade , Relação Dose-Resposta a Droga , Dimetoato
6.
Environ Int ; 175: 107940, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-37119652

RESUMO

The research framework combining global sensitivity analysis (GSA) with quantitative high-throughput screening (qHTS), called GSA-qHTS, provides a potentially feasible way to screen for important factors that induce toxicities of complex mixtures. Despite its value, the mixture samples designed using the GSA-qHTS technique still have a shortage of unequal factor levels, which leads to an asymmetry in the importance of elementary effects (EEs). In this study, we developed a novel method for mixture design that enables equal frequency sampling of factor levels (called EFSFL) by optimizing both the trajectory number and the design and expansion of the starting points for the trajectory. The EFSFL has been successfully employed to design 168 mixtures of 13 factors (12 chemicals and time) that each have three levels. By means of high-throughput microplate toxicity analysis, the toxicity change rules of the mixtures are revealed. Based on EE analysis, the important factors affecting the toxicities of the mixtures are screened. It was found that erythromycin is the dominant factor and time is an important non-chemical factor in mixture toxicities. The mixtures can be classified into types A, B, and C mixtures according to their toxicities at 12 h, and all the types B and C mixtures contain erythromycin at the maximum concentration. The toxicities of the type B mixtures increase firstly over time (0.25 âˆ¼ 9 h) and then decrease (12 h), while those of the type C mixtures consistently increase over time. Some type A mixtures produce stimulation that increases with time. With the present new approach to mixture design, the frequency of factor levels in mixture samples is equal. Consequently, the accuracy of screening important factors is improved based on the EE method, providing a new method for the study of mixture toxicity.


Assuntos
Vibrio , Eritromicina/farmacologia , Misturas Complexas , Ensaios de Triagem em Larga Escala
7.
Biomed Mater ; 9(6): 065007, 2014 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-25384201

RESUMO

The beneficial effect of a porous structure on the biological functions of calcium phosphate bulk ceramic or scaffold has been well documented. Nevertheless, the effect of a porous structure on the in vivo performance of hydroxyapatite (HA) coatings has been rarely reported, partly due to the difficulty in synthesizing porous HA coatings suitable for commercial applications. In this study, we have carried out a systematic in vivo study of porous HA-coated Ti implants (with and without surface modification) prepared by the liquid precursor plasma spraying process, in terms of its osteoconductivity and osteoinductivity. The results suggest the clear advantage of the porous structure over the dense structure, despite the pore structure (about 48% porosity and less than 100 µm average pore size) being far from the ideal pore structure reported for bulk ceramic. The porous HA-coated implant significantly promotes early bone ingrowth at the pre-generated defective region, and early fixation at the bone-implant interface, especially at early implantation time (one month), showing about 120% and 40% increases respectively over those of the dense HA-coated implants prepared by the conventional atmospheric plasma spraying process. Moreover, the porous structure can be readily used to incorporate collagen/rh-BMP2, which demonstrates clear ectopic bone formation. Overall, the results suggest the augmentation of bone ingrowth is significant for HA coatings with a porous structure, which is critical for the early fixation and long-term stability of medical implants.


Assuntos
Materiais Biocompatíveis/química , Regeneração Óssea , Materiais Revestidos Biocompatíveis/química , Durapatita/química , Animais , Proteína Morfogenética Óssea 2/química , Substitutos Ósseos , Fosfatos de Cálcio/química , Colágeno/química , Cães , Humanos , Lipopolissacarídeos/química , Masculino , Teste de Materiais , Microscopia Eletrônica de Varredura , Porosidade , Próteses e Implantes , Coelhos , Proteínas Recombinantes/química , Propriedades de Superfície , Titânio/química
8.
Int J Nanomedicine ; 7: 3365-78, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22848165

RESUMO

INTRODUCTION: In recent years, interest in magnetic biomimetic scaffolds for tissue engineering has increased considerably. A type of magnetic scaffold composed of magnetic nanoparticles (MNPs) and hydroxyapatite (HA) for bone repair has been developed by our research group. AIM AND METHODS: In this study, to investigate the influence of the MNP content (in the scaffolds) on the cell behaviors and the interactions between the magnetic scaffold and the exterior magnetic field, a series of MNP-HA magnetic scaffolds with different MNP contents (from 0.2% to 2%) were fabricated by immersing HA scaffold into MNP colloid. ROS 17/2.8 and MC3T3-E1 cells were cultured on the scaffolds in vitro, with and without an exterior magnetic field, respectively. The cell adhesion, proliferation and differentiation were evaluated via scanning electron microscopy; confocal laser scanning microscopy; and 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), alkaline phosphatase, and bone gla protein activity tests. RESULTS: The results demonstrated the positive influence of the magnetic scaffolds on cell adhesion, proliferation, and differentiation. Further, a higher amount of MNPs on the magnetic scaffolds led to more significant stimulation. CONCLUSION: The magnetic scaffold can respond to the exterior magnetic field and engender some synergistic effect to intensify the stimulating effect of a magnetic field to the proliferation and differentiation of cells.


Assuntos
Durapatita/química , Nanopartículas de Magnetita/química , Nanocompostos/química , Osteoblastos/citologia , Tecidos Suporte/química , Fosfatase Alcalina/metabolismo , Análise de Variância , Animais , Adesão Celular/efeitos dos fármacos , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Durapatita/farmacologia , Camundongos , Osteoblastos/efeitos dos fármacos , Osteocalcina/metabolismo , Ratos , Estatísticas não Paramétricas
9.
J Nanosci Nanotechnol ; 12(11): 8437-42, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23421227

RESUMO

Superparamagnetic iron oxide nanoparticles (SPIONs) with high saturation magnetization are successfully synthesized via thermal decomposition method by doping Mn and Zn elements simultaneously. The synthesis procedure was modified according to the thermal stabilities of the precursors, in order to ensure that the stoichiometry of the synthesized samples can be retained exactly from the starting ratios of the Fe/Mn/Zn in the initial precursors. As a result, the saturation magnetization of the dual-doped nanoparticles increased about 23% compared to that without the dopants. The superparamagnetic nanoparticles had narrow size distribution and the average diameter was about 8 nm. XRD and HRTEM analyses also indicated that the materials had a cubic spinel structure.


Assuntos
Cristalização/métodos , Dextranos/síntese química , Nanopartículas de Magnetita/química , Nanopartículas de Magnetita/ultraestrutura , Manganês/química , Zinco/química , Substâncias Macromoleculares/química , Teste de Materiais , Conformação Molecular , Tamanho da Partícula , Propriedades de Superfície
10.
Nanotechnology ; 22(22): 225604, 2011 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-21454944

RESUMO

Monodisperse superparamagnetic Fe(3)O(4)/polymethyl methacrylate (PMMA) composite nanospheres with high saturation magnetization were successfully prepared by a facile novel miniemulsion polymerization method. The ferrofluid, MMA monomer and surfactants were co-sonicated and emulsified to form stable miniemulsion for polymerization. The samples were characterized by DLS, TEM, FTIR, XRD, TGA and VSM. The diameter of the Fe(3)O(4)/PMMA composite nanospheres by DLS was close to 90 nm with corresponding polydispersity index (PDI) as small as 0.099, which indicated that the nanospheres have excellent homogeneity in aqueous medium. The TEM results implied that the Fe(3)O(4)/PMMA composite nanospheres had a perfect core-shell structure with about 3 nm thin PMMA shells, and the core was composed of many homogeneous and closely packed Fe(3)O(4) nanoparticles. VSM and TGA showed that the Fe(3)O(4)/PMMA composite nanospheres with at least 65% high magnetite content were superparamagnetic, and the saturation magnetization was as high as around 39 emu g(-1) (total mass), which was only decreased by 17% compared with the initial bare Fe(3)O(4) nanoparticles.


Assuntos
Compostos Férricos/química , Nanocompostos/química , Nanosferas/química , Nanotecnologia/métodos , Polimetil Metacrilato/química , Compostos Férricos/síntese química , Magnetismo , Nanocompostos/ultraestrutura , Nanosferas/ultraestrutura , Polimerização , Polimetil Metacrilato/síntese química
11.
Biomed Mater ; 5(4): 045009, 2010 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-20644241

RESUMO

The biomedical applications of poly(l-lactide) (PLLA) were limited by its high crystallinity. In this paper, the copolymerization of trimethylene carbonate (TMC) and l-lactide (LLA) was carried out to improve the flexibility of PLLA. The effects of feeding dose, reaction temperature and polymerization time were investigated, and the copolymers were characterized with (1)H nuclear magnetic resonance, Fourier transform infrared reflection, gel permeation chromatography differential scanning calorimetry, thermogravimetric analysis and x-ray diffraction. The copolymers were electrospun to form porous films to study their cell compatibility. The results showed that the composition of the copolymer was nearly the same as that in the feeding dose, and the molecular weight of the copolymer decreased with increasing TMC content. The decrease in the reaction temperature and polymerization time would increase the molecular weight, but the composition deviates from the feeding dose. NIH/3T3 mouse fibroblast cells were cultured on the electrospun films. The morphology and proliferation of the cells were studied. The results implied that the cell compatibility of poly(l-lactide-co-trimethylene carbonate) copolymer was much better than that of the PLLA homopolymer.


Assuntos
Sobrevivência Celular/efeitos dos fármacos , Dioxanos/química , Dioxanos/farmacologia , Eletroquímica/métodos , Ácido Láctico/química , Ácido Láctico/farmacologia , Membranas Artificiais , Polímeros/química , Polímeros/farmacologia , Células 3T3 , Animais , Materiais Biocompatíveis/síntese química , Materiais Biocompatíveis/farmacologia , Teste de Materiais , Camundongos , Poliésteres , Rotação
12.
Acta Crystallogr Sect E Struct Rep Online ; 66(Pt 7): o1521, 2010 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-21587771

RESUMO

In the title compound, C(40)H(66)O(4), the C and O atoms of the propinyl and dodecoxyl substituents are nearly coplanar with the benzene ring, 1.735 (6), 8.804 (1), 8.786 (1) and 9.577 (3)°, respectively. In the crystal, mol-ecules are connected by inter-molecular O-H⋯O hydrogen bonds.

13.
Molecules ; 14(3): 1324-31, 2009 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-19325526

RESUMO

Forsythosides H-J (1-3), three new caffeoyl phenylethanoid glycosides (CPGs), were isolated from the fruits of Forsythia suspense (Thunb.) Vahl., together with six known phenylethanoid glycosides: Forsythoside A (4), Forsythoside F (5), Forsythoside E (6), 2-(3,4-dihydroxyphenyl)ethyl-beta-D-glucopyranoside (7), phenethyl alcohol beta-D-xylo-pyranosyl-(1-->6)-beta-D-glucopyranoside (8) and calceolarioside B (9). Their structures were determined by spectroscopic and chemical methods.


Assuntos
Forsythia/química , Glicosídeos/química , Álcool Feniletílico/química , Glicosídeos/isolamento & purificação , Estrutura Molecular , Álcool Feniletílico/isolamento & purificação
14.
Biomacromolecules ; 9(10): 2578-85, 2008 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-18665638

RESUMO

Amphiphilic hyperbranched core-shell polymers with folate moieties as the targeting groups were synthesized and characterized. The core of the amphiphilic polymers was hyperbranched aliphatic polyester Boltorn H40. The inner part and the outer shell of the amphiphilic polymers were composed of hydrophobic poly(epsilon-caprolactone) segments and hydrophilic poly(ethylene glycol) (PEG) segments, respectively. To achieve tumor cell targeting property, folic acid was further incorporated to the surface of the amphiphilic polymers via a coupling reaction between the hydroxyl group of the PEG segment and the carboxyl group of folic acid. The polymers were characterized by (1)H NMR, (13)C NMR, and combined size-exclusion chromatography and multiangle laser light scattering analysis. The nanoparticles of the amphiphilic polymers prepared by dialysis method were characterized by transmission electron microscopy and particle size analysis. Two antineoplastic drugs, 5-fluorouracil and paclitaxel, were encapsulated into the nanoparticles. The drug release property and the targeting of the drug-loaded nanoparticles to different cells were evaluated in vitro. The results showed the drug-loaded nanoparticles exhibited enhanced cell inhibition because folate targeting increased the cytotoxicity of drug-loaded nanoparticles against folate receptor expressing tumor cells.


Assuntos
Antineoplásicos/administração & dosagem , Sistemas de Liberação de Medicamentos , Polímeros/química , Cromatografia/métodos , Portadores de Fármacos , Ácido Fólico/química , Células HeLa , Humanos , Espectroscopia de Ressonância Magnética , Modelos Químicos , Conformação Molecular , Nanopartículas/química , Neoplasias/tratamento farmacológico , Polietilenoglicóis/química , Espalhamento de Radiação
15.
J Nanosci Nanotechnol ; 8(5): 2377-84, 2008 May.
Artigo em Inglês | MEDLINE | ID: mdl-18572652

RESUMO

A series of biocompatible and stimuli-sensitive poly(N-isopropylacrylamide-co-propyl acrylic acid) (P(NIPAAm-co-PAAc)) nanogels were synthesized by emulsion polymerization. In addition, polyethyleneimine (PEI) was further grafted to modify the PNIPAAm-based nanogels. The P(NIPAAm-co-PAAc)-g-PEI nanogels exhibited good thermosensitivity as well as pH sensitivity. Transmission electron microscopy (TEM) showed that the P(NIPAAm-co-PAAc)-g-PEI and P(NIPAAm-co-PAAc) nanogels displayed well dispersed spherical morphology. The mean sizes of the nanogels measured by dynamic light scattering (DLS) were from 100 nm to 500 nm at different temperatures. The cytotoxicity study indicated P(NIPAAm-co-PAAc) nanogels exhibited a better biocompatibility than both PNIPAAm nanogel and P(NIPAAm-co-PAAc)-g-PEI nanogel although all the three kinds of nanogels did not exhibit apparent cytotoxicity. The drug-loaded nanogels, especially the PEI-grafted nanogels, showed temperature-trigged controlled release behaviors, indicating the potential applications as an intelligent drug delivery system.


Assuntos
Acrilamidas/química , Materiais Biocompatíveis/química , Portadores de Fármacos , Géis , Nanopartículas , Polietilenoimina/química , Polímeros/química , Resinas Acrílicas , Concentração de Íons de Hidrogênio , Espectroscopia de Ressonância Magnética , Microscopia Eletrônica de Transmissão , Temperatura
16.
Biomaterials ; 29(4): 497-505, 2008 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17959241

RESUMO

A multifunctional micellar drug carrier formed by the thermosensitive and biotinylated double-hydrophilic block copolymer (DHBC), biotin-poly(ethylene glycol)-block-poly(N-isopropylacrylamide-co-N-hydroxymethylacrylamide) (biotin-PEG-b-P(NIPAAm-co-HMAAm)), was designed and prepared. The P(NIPAAm-co-HMAAm) block with an molar feed ratio of NIPAAm and HMAAm (10:1) was identified to exhibit the reversible phase transition at the lower critical solution temperature (LCST) of 36.7 degrees C. Cytotoxicity study indicated that the biotin-PEG-b-P(NIPAAm-co-HMAAm) copolymer did not exhibit obvious cytotoxicity. The block copolymer was capable of self-assembling into micelle in water. Transmission electron microscopy showed that the self-assembled micelles were regularly spherical in shape. The anticancer drug methotrexate (MTX) was loaded in the micelles and the in vitro release behaviors of MTX at different temperatures were investigated. The association of biotin molecule with the copolymer was confirmed by a unique capillary electrophoresis immunoassay (CEIA) method based on enhanced chemiluminescence (CL) detection. The fluorescence spectroscopy analysis as well as confocal microscopy studies confirmed the DHBC drug carriers could specifically and efficiently bind to cancer cells with pretreatment of biotin-transferrin, suggesting that the multifunctionalized DHBC micelle may be a useful drug carrier for tumor targeting.


Assuntos
Resinas Acrílicas/química , Biotina/química , Portadores de Fármacos/química , Micelas , Neoplasias , Polietilenoglicóis/química , Água/química , Resinas Acrílicas/toxicidade , Biotina/toxicidade , Biotinilação , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Portadores de Fármacos/toxicidade , Humanos , Espectroscopia de Ressonância Magnética , Microscopia Confocal , Microscopia Eletrônica de Transmissão , Estrutura Molecular , Polietilenoglicóis/toxicidade , Sensibilidade e Especificidade , Temperatura
17.
Zhonghua Xin Xue Guan Bing Za Zhi ; 33(10): 945-9, 2005 Oct.
Artigo em Chinês | MEDLINE | ID: mdl-16266490

RESUMO

OBJECTIVE: Currents contributing repolarization in rabbit ventricular myocyte are very complex since the I(To.s) covers almost the whole repolarization phase of the action potential. The other components of repolarizing currents, as I(Kr) and I(Ks) are small. The purpose of this study is to investigate whether or not there are other currents in rabbit ventricular repolarization. METHODS: Ion currents of rabbit ventricular myocyte were recorded using the whole-cell patch-clamp technique. RESULTS: In the present work, an nonselective cation current was identified by replacing the K(+) with Cs(+) in the bathing and pipette solutions. The outward current elicited by depolarizing potentials could be inhibited by Gd(3+), an effective inhibitor of nonselective cation currents. Depleting Ca(2+) and Mg(2+) in the bathing solution, the amplitudes of this outward current increased by 40%-116% at +60 mV, and adding 2 micromol/L insulin to the solution (with normal concentration of Ca(2+) and Mg(2+) in Tyrode's solution), the amplitude increased by 30%-60% at +60 mV. CONCLUSION: It is suggested that a nonselective cation current in rabbit ventricular myocytes may play an important role in the repolarization of the action potential in rabbit ventricle. Changes of nonselective cation current will lead to induce or inhibit arrhythmia.


Assuntos
Potenciais da Membrana , Miócitos Cardíacos/fisiologia , Animais , Técnicas de Patch-Clamp , Coelhos
18.
J Control Release ; 107(1): 53-64, 2005 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-16005093

RESUMO

Blank and bovine serum albumin (BSA)-loaded microspheres based on poly(lactic-acid-alt-glycolic acid) (D,L-PLGA50) and poly(epsilon-caprolactone)-b-poly(lactic-acid-alt-glycolic acid) (PCL-b-D,L-PLGA50) were successfully fabricated using water-in-oil-in-water (w/o/w) double-emulsion extraction/evaporation technique. In vitro degradation of the blank microspheres was characterized by techniques including nuclear magnetic resonance (1H NMR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The PCL-b-D,L-PLGA50 copolymer (Mn: number-average molecular weight, Mw: weight-average molecular weight, Mn=44800, Mw/Mn=MWD=1.24, epsilon-caprolactone (CL) %=20.4% in molar ratio) had similar rate of molecular weight reduction compared with the D,L-PLGA50 copolymer before 5 weeks of in vitro degradation. The BSA % loading efficiency of microspheres was mainly controlled by both block copolymer composition and macromolecular architecture, while the sequence structure and the molecular weight of copolymer had no apparent effect on it. Significantly, The PCL-b-D,L-PLGA50 copolymer microspheres showed good release profiles with a nearly constant release during 20-110 days.


Assuntos
Preparações de Ação Retardada/metabolismo , Ácido Láctico/metabolismo , Microesferas , Ácido Poliglicólico/metabolismo , Polímeros/metabolismo , Animais , Varredura Diferencial de Calorimetria , Bovinos , Cromatografia em Gel , Preparações de Ação Retardada/química , Técnicas In Vitro , Ácido Láctico/química , Espectroscopia de Ressonância Magnética , Microscopia Eletrônica de Varredura , Peso Molecular , Ácido Poliglicólico/química , Polímeros/química , Soroalbumina Bovina/metabolismo , Temperatura , Fatores de Tempo
19.
Chem Pharm Bull (Tokyo) ; 53(6): 620-4, 2005 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15930770

RESUMO

Clotrimazole (CT)-containing proliposomes were prepared by penetrating an ethanol solution of CT and Egg phosphatidylcholine (PC) into microporous sorbitol particles, followed by vacuum evaporation of the solvent. As a result, CT proliposomes with free-flowing flowability were obtained. On contact with water, the proliposomes were rapidly converted into a liposomal dispersion, in which a certain amount of CT was entrapped by the liposomes. The result in scanning electronic micrograph confirmed the formation of liposomes structures from proliposomes, and the particles revealed round or ellipse. The ratio of drug to total lipid, ratio of PC to cholesterol and ratio of lipid to sorbitol affected the entrapment efficiency (EE%). The EE% of optimized formulation (CT 10 mg, 0.1 g total lipid, PC/CH ratio is 60 : 40 and 1 g sorbitol) in this investigation was 96.2+/-1.5%. The proliposomes system can provide sustaining release in simulated vaginal fluid at 37+/-1 degrees C for 24 h. In-vivo performance of blank proliposomes, a physical mixture of sorbitol and drug, clotrimazole proliposomes and commercial ointment formulation were evaluated using antifungal activity test. At 7 d post-dose, the c.f.u. of C. albicans decreased in proliposomes-treated groups than ointment and the physical mixture (t-Student, p<0.05). The results indicated that CT-containing vaginal proliposomes prolonged drug release and may increase amount of drug retention into the mucosa to result in more antifungal efficacy. In addition, CT-proliposomes did not affect the morphology of vaginal tissues. Therefore, the dosage form might be further developed for safe, convenient, and effective treatment of vaginal candidasis with reduced dosing interval.


Assuntos
Clotrimazol/administração & dosagem , Clotrimazol/síntese química , Pró-Fármacos/administração & dosagem , Pró-Fármacos/síntese química , Animais , Clotrimazol/farmacocinética , Avaliação Pré-Clínica de Medicamentos/métodos , Feminino , Lipossomos , Pró-Fármacos/farmacocinética , Ratos , Ratos Sprague-Dawley , Vagina/citologia , Vagina/efeitos dos fármacos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...