Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 28
Filtrar
1.
Materials (Basel) ; 16(3)2023 Feb 02.
Artículo en Inglés | MEDLINE | ID: mdl-36770300

RESUMEN

Three sodium polyacrylate copolymers PD0x (Poly acrylic acid-co-sodium 4-vinylbenzenesulfonate or PD01; Poly acrylic acid-co-sodium 4-vinylbenzenesulfonate-co-hydroxyethyl methacrylate or PD02 and Poly methyl methacrylate-co-acrylic acid-co-sodium 4-vinylbenzenesulfonate-co-hydroxyethyl methacrylate or PD03) were synthesized as water-based dispersants for grinding red-brown pigment ZnFe1.2Cr0.8O4 particles prepared by the solid phase method (S-ZnF). The particle size distribution, viscosity of suspensions, and adsorption capacity of dispersants were explored by laser particle size analysis, viscometer, and thermogravimetry (TG), respectively. The application of 2 wt.% dispersant PD02 in the S-ZnF suspension ground for 90 min can deliver a finer product with the narrower particle size distribution. The added dispersant PD02 in the grinding process of the S-ZnF particles exhibits a suitable viscosity of the suspension and generates more hydrogen bonds on the S-ZnF particle surface. The sulfonic acid groups (SO3-) and carboxylic acid groups (-COO-) in the dispersant PD02 can also provide a strong charge density, which is favorable for the dispersion and grinding of the S-ZnF particles in the suspensions. Furthermore, the adsorption behavior of polymeric dispersant PD02 adsorbed on the S-ZnF particles surface was simulated and analyzed by adsorption thermodynamic models and adsorption kinetic models. It is indicated that the adsorption thermodynamic behavior of dispersant PD02 adsorbed on the S-ZnF particles surface follows the Langmuir model, and the adsorption process is endothermic and a random process with increased confusion during the grinding process. In addition, the adsorption kinetics of dispersant PD02 adsorbed on the S-ZnF particles surface are more in line with the pseudo-first-order kinetic models. Therefore, the adsorption process of dispersant PD02 on the S-ZnF particles surface can be considered as a single-surface adsorption process.

2.
Biomed Pharmacother ; 148: 112254, 2022 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-35183405

RESUMEN

BACKGROUND: Yiqi Tongluo Fang (YQTLF) is an effective prescription for the treatment of diabetic retinopathy (DR), but its mechanism of action remains unclear. METHOD: The content of YQTLF was determined using liquid and gas chromatography-mass spectrometry (LC-MS and GC-MS, respectively). Twenty-five Sprague Dawley (SD) rats were randomly selected as the normal control group. One hundred SD streptozotocin-induced diabetes (type 1) rats were randomly divided into diabetic control, diabetic+insulin+ calcium dobesilate (CaD), and diabetic+insulin+ YQTLF groups, with 25 rats in each group. Bodyweight level was measured every 2 weeks. After 12 weeks of gavage, the glucose levels, lipids, oxidative stress, inflammation, retinal histopathology, and the blood-retinal barrier were assessed in each group. The p38 MAPK pathway was changed to explore its internal mechanism. The measurement data were expressed as mean ± standard deviation, and different statistical methods were used according to a normal distribution, square error, or not. RESULTS: A total of 1024 valid peaks were identified in YQTLF using GC-MS. YQTLF significantly lowered the fasting blood glucose levels in diabetic rats. YQTLF early inhibited changes in retinal histology, capillaries, cells, and tight junction proteins (such as ZO-1, occludin, claudin-5, and VE-cadherin) before the formation and development of DR. These findings correlated with the alleviation of glucolipid metabolism, inflammation, and oxidative stress. The lncRNA MALAT1 and the PRC 2/p38 MAPK-related pathway, such as the expression of EZH2, SUZ12, EED, p38 MAPK, MMP-9, and VEGFR, were also correlated. CONCLUSION: We have demonstrated the molecular and cellular mechanisms underlying the preventive and delayed development and formation of DR. YQTLF prevents changes in dyslipidemia, retinal histology, capillaries, cells, and tight junction proteins. These protective effects appear to be linked to its antioxidant and anti-inflammatory effects, which prevent the activation of intracellular signaling pathways, such as the lncRNA MALAT1 and PRC 2/p38 MAPK-related pathway.


Asunto(s)
Diabetes Mellitus Experimental , Retinopatía Diabética , Animales , Antiinflamatorios/farmacología , Antiinflamatorios/uso terapéutico , Antioxidantes/farmacología , Antioxidantes/uso terapéutico , Diabetes Mellitus Experimental/tratamiento farmacológico , Retinopatía Diabética/tratamiento farmacológico , Retinopatía Diabética/metabolismo , Retinopatía Diabética/prevención & control , Medicamentos Herbarios Chinos , Ratas , Ratas Sprague-Dawley
3.
J Vet Intern Med ; 35(4): 1663-1672, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-33993546

RESUMEN

BACKGROUND: Point-of-care (POC) N-terminal pro B-type natriuretic peptide (NT-proBNP) ELISA test has been evaluated for screening cats for cardiac disease in the referral veterinary setting but less is known about its use in general practice (GP). OBJECTIVES: To evaluate the diagnostic utility of a POC NT-proBNP ELISA in cats seen in GPs. ANIMALS: Two hundred and seventeen apparently healthy cats from 21 GPs. METHODS: This was a prospective, cross-sectional study. Cardiac auscultation and POC NT-proBNP ELISA were done by veterinarians at their GPs. After enrollment at GPs, cats were sent to a cardiology referral hospital for cardiac auscultation and echocardiographic diagnosis. Results were interpreted based on whether cats had normal or abnormal echocardiographic findings. RESULTS: Point-of-care NT-proBNP ELISA results differentiated cats in the abnormal group from those in the normal group with a sensitivity of 43%, specificity of 96%. In cats with a heart murmur at GPs, POC NT-proBNP ELISA results differentiated cats in the abnormal group from those in the normal group with a sensitivity of 71% and a specificity of 92%. CONCLUSION AND CLINICAL IMPORTANCE: In apparently healthy cats in GPs, positive POC NT-proBNP results are associated with heart disease, warranting an echocardiogram, but negative results do not reliably exclude heart disease. These results suggest POC NT-proBNP is not an effective screening test for apparently healthy cats in GPs, although its performance is improved if it is used only in cats that have a heart murmur.


Asunto(s)
Enfermedades de los Gatos , Medicina General , Cardiopatías , Insuficiencia Cardíaca , Animales , Biomarcadores , Enfermedades de los Gatos/diagnóstico , Gatos , Estudios Transversales , Cardiopatías/diagnóstico , Cardiopatías/veterinaria , Insuficiencia Cardíaca/veterinaria , Péptido Natriurético Encefálico , Fragmentos de Péptidos , Sistemas de Atención de Punto , Estudios Prospectivos
4.
Theranostics ; 10(22): 10092-10105, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32929336

RESUMEN

Rheumatoid arthritis (RA), a common inflammatory disorder of the joints characterized by synovitis and pannus formation, often results in irreversible joint erosion and disability. Methotrexate (MTX) is the first-line drug against RA, but the therapeutic effects are sub-optimal due to its poor retention at the target sites and systemic side effects. Multifunctional nanoparticles are highly promising agents for minimally invasive, traceable and effective targeted therapy. Methods: This study developed iRGD peptide-functionalized echogenic liposomes (iELPs) which encapsulates MTX and indocyanine green (ICG) fluorescent probe through the thin film-hydration method. Results: The resulting iELPs showed high affinity for endothelial cells overexpressing αvß3 integrin, favorable acoustic response and fluorescence tracking properties. Also, near-infrared (NIR) fluorescence imaging of iELPs and ultrasound-triggered drug release of MTX were proved in a mouse RA model, greatly improving the therapeutic efficacy and reducing MTX side effects. Histological assessment of the articular tissues further revealed significantly lower inflammatory cell infiltration and angiogenesis in the iELPs-treated and sonicated mice. Conclusion: Our study provides a promising nanoplatform for integrating ultrasound-controlled drug release and NIR fluorescence imaging for RA treatment.


Asunto(s)
Artritis Reumatoide/tratamiento farmacológico , Colorantes Fluorescentes/administración & dosificación , Liposomas/metabolismo , Metotrexato/farmacología , Oligopéptidos/farmacología , Imagen Óptica/métodos , Terapia por Ultrasonido/métodos , Animales , Línea Celular , Células Endoteliales/efectos de los fármacos , Células Endoteliales/metabolismo , Células Endoteliales de la Vena Umbilical Humana , Humanos , Verde de Indocianina/metabolismo , Integrina alfaVbeta3/metabolismo , Masculino , Ratones , Células RAW 264.7 , Espectroscopía Infrarroja Corta/métodos , Porcinos , Ondas Ultrasónicas
5.
Int J Nanomedicine ; 13: 1841-1850, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-29615837

RESUMEN

BACKGROUND: Rheumatoid arthritis (RA) is a common inflammatory disorder characterized primarily by synovitis and pannus formation in multiple joints, causing joints destruction and irreversible disability in most cases. Early diagnosis and effective therapy monitoring of RA are of importance for achieving the favorable prognosis. METHODS: We first prepared the targeted fluorescence probes, and then explored the feasibility of near-infrared (NIR) fluorescence molecular imaging to detect and evaluate the RA via the targeted fluorescence probes by quantitative analysis in this study. RESULTS: The targeted fluorescence probes (indocyanine green-liposomes decorated with iRGD peptide [iLPs]) was successfully prepared. The quantitative analysis found that strong fluorescence signal was detected in inflamed paws and the fluorescence signal in iLPs group was 3.03-fold higher than that in non-targeted (indocyanine green-liposomes decorated without iRGD peptide [LPs]) group (P<0.01) at 15 min after injection, whereas the fluorescence signal from iLPs signal can almost not be observed in the non-inflamed paws, showing the high sensitivity and accuracy for arthritis by the NIR fluorescence imaging based on iLPs. CONCLUSION: The NIR fluorescence imaging by iLPs may facilitate improved arthritis diagnosis and early assessment of the disease progression by providing an in vivo characterization of angiogenesis in inflammatory joint diseases.


Asunto(s)
Artritis Reumatoide/diagnóstico por imagen , Colorantes Fluorescentes/química , Liposomas/administración & dosificación , Imagen Molecular/métodos , Sinovitis/diagnóstico por imagen , Animales , Artritis Reumatoide/complicaciones , Colorantes Fluorescentes/farmacocinética , Colorantes Fluorescentes/uso terapéutico , Células Endoteliales de la Vena Umbilical Humana , Humanos , Verde de Indocianina/química , Liposomas/química , Liposomas/farmacocinética , Masculino , Ratones Endogámicos DBA , Oligopéptidos , Imagen Óptica/métodos , Sinovitis/etiología , Distribución Tisular
6.
Nan Fang Yi Ke Da Xue Xue Bao ; 37(10): 1283-1289, 2017 Oct 20.
Artículo en Chino | MEDLINE | ID: mdl-29070455

RESUMEN

OBJECTIVE: To prepare internalized RGD (iRGD) modified echogenic liposomes containing methotrexate (MTX) and indocyanine green (ICG) (iRGD MTX ICG ELIP) and evaluate its targeting efficiency and inhibitory effect combined with ultrasound on synovial cells. METHODS: iRGD MTX ICG ELIP was prepared by the thin film rehydration and freeze-lyophilization method and its general characteristics and acoustic responsiveness were assessed. The targeting effect of the prepared liposome was observed by assessing its cell uptake in vitro. In a mouse model of rheumatiod arthritis, the targeting effect of the prepared liposome was determined by detecting the fluorescence intensity of the drug in arthrosis. The inhibitory effect of iRGD MTX ICG ELIP combined with ultrasound on synovial MH7A cells in vitro were investigated using CCK8 test. RESULTS: The average diameter and zeta potential of iRGD MTX ICG ELIP was 134.4∓17.61 nm and 10.07∓4.28 mV, and the entrapment efficiency of MTX and ICG was (62.56∓0.77)% and (95.13∓0.82)%, respectively. With ultrasound exposure, the release of MTX and ICG from iRGD MTX ICG ELIP increased with the ultrasound intensity and with the exposure time. In HUVECs, the uptake efficiency of iRGD MTX ICG ELIP was 1.89 times higher than that of non targeted MTX ICG ELIP (P<0.05). In vivo imaging of mouse joint with rheumatiod arthritis showed that the fluorescence intensity of iRGD MTX ICG ELIP was significantly stronger than that of the non targeted liposome. CCK8 assay showed that iRGD MTX ICG ELIP combined with ultrasound resulted in a survival rate of MH7A cells of (32.49∓3.04)%, significantly lower than the rate of cells treated with iRGD MTX ICG ELIP but without ultrasound (P<0.05). CONCLUSIONS: iRGD MTX ICG ELIP has a suitable particle size and can effectively target HUVECs and the joints with rheumatiod arthritis. With a good drug entrapment efficiency and acoustic responsiveness, the drug loaded liposome shows enhanced inhibitory effect on MH7A cells combined with ultrasound in vitro, suggesting its potential in the treatment of rheumatoid arthritis.


Asunto(s)
Artritis Reumatoide/diagnóstico por imagen , Artritis Reumatoide/tratamiento farmacológico , Liposomas/química , Metotrexato/farmacología , Oligopéptidos/química , Animales , Células Endoteliales de la Vena Umbilical Humana , Humanos , Verde de Indocianina , Ratones , Tamaño de la Partícula , Ultrasonografía
7.
Sci Rep ; 6: 32444, 2016 09 01.
Artículo en Inglés | MEDLINE | ID: mdl-27580824

RESUMEN

Mutations in human CLC-1 chloride channel are associated with the skeletal muscle disorder myotonia congenita. The disease-causing mutant A531V manifests enhanced proteasomal degradation of CLC-1. We recently found that CLC-1 degradation is mediated by cullin 4 ubiquitin ligase complex. It is currently unclear how quality control and protein degradation systems coordinate with each other to process the biosynthesis of CLC-1. Herein we aim to ascertain the molecular nature of the protein quality control system for CLC-1. We identified three CLC-1-interacting proteins that are well-known heat shock protein 90 (Hsp90)-associated co-chaperones: FK506-binding protein 8 (FKBP8), activator of Hsp90 ATPase homolog 1 (Aha1), and Hsp70/Hsp90 organizing protein (HOP). These co-chaperones promote both the protein level and the functional expression of CLC-1 wild-type and A531V mutant. CLC-1 biosynthesis is also facilitated by the molecular chaperones Hsc70 and Hsp90ß. The protein stability of CLC-1 is notably increased by FKBP8 and the Hsp90ß inhibitor 17-allylamino-17-demethoxygeldanamycin (17-AAG) that substantially suppresses cullin 4 expression. We further confirmed that cullin 4 may interact with Hsp90ß and FKBP8. Our data are consistent with the idea that FKBP8 and Hsp90ß play an essential role in the late phase of CLC-1 quality control by dynamically coordinating protein folding and degradation.


Asunto(s)
Canales de Cloruro/genética , Proteínas HSP90 de Choque Térmico/genética , Proteínas de Homeodominio/genética , Chaperonas Moleculares/genética , Proteínas de Unión a Tacrolimus/genética , Proteínas Supresoras de Tumor/genética , Canales de Cloruro/antagonistas & inhibidores , Canales de Cloruro/metabolismo , Proteínas Cullin/genética , Proteínas Cullin/metabolismo , Inhibidores de Cisteína Proteinasa/farmacología , Regulación de la Expresión Génica , Vectores Genéticos/química , Vectores Genéticos/metabolismo , Células HEK293 , Proteínas HSP90 de Choque Térmico/metabolismo , Proteínas de Homeodominio/metabolismo , Humanos , Lentivirus/genética , Lentivirus/metabolismo , Leupeptinas/farmacología , Modelos Biológicos , Chaperonas Moleculares/metabolismo , Miotonía Congénita/genética , Miotonía Congénita/metabolismo , Miotonía Congénita/patología , Técnicas de Placa-Clamp , Complejo de la Endopetidasa Proteasomal/efectos de los fármacos , Complejo de la Endopetidasa Proteasomal/metabolismo , Proteolisis , ARN Interferente Pequeño/genética , ARN Interferente Pequeño/metabolismo , Transducción de Señal , Proteínas de Unión a Tacrolimus/metabolismo , Transfección , Proteínas Supresoras de Tumor/metabolismo , Ubiquitinación/efectos de los fármacos
8.
Chem Sci ; 7(1): 759-765, 2016 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-29896359

RESUMEN

The efficiency of physisorption-based separation of gas-mixtures depends on the selectivity of adsorbent which is directly linked to size, shape, polarizability and other physical properties of adsorbed molecules. Commensurate adsorption is an interesting and important adsorption phenomenon, where the adsorbed amount, location, and orientation of an adsorbate are commensurate with the crystal symmetry of the adsorbent. Understanding this phenomenon is important and beneficial as it can provide vital information about adsorbate-adsorbent interaction and adsorption-desorption mechanism. So far, only sporadic examples of commensurate adsorption have been reported in porous materials such as zeolites and metal organic frameworks (MOFs). In this work we show for the first time direct structural evidence of commensurate-to-incommensurate transition of linear hydrocarbon molecules (C2-C7) in a microporous MOF, by employing a number of analytical techniques including single crystal X-ray diffraction (SCXRD), in situ powder X-ray diffraction coupled with differential scanning calorimetry (PXRD-DSC), gas adsorption and molecular simulations.

9.
PLoS One ; 9(10): e110423, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-25333352

RESUMEN

Eag (Kv10) and Erg (Kv11) belong to two distinct subfamilies of the ether-à-go-go K+ channel family (KCNH). While Erg channels are characterized by an inward-rectifying current-voltage relationship that results from a C-type inactivation, mammalian Eag channels display little or no voltage-dependent inactivation. Although the amino (N)-terminal region such as the eag domain is not required for the C-type inactivation of Erg channels, an N-terminal deletion in mouse Eag1 has been shown to produce a voltage-dependent inactivation. To further discern the role of the eag domain in the inactivation of Eag1 channels, we generated N-terminal chimeras between rat Eag (rEag1) and human Erg (hERG1) channels that involved swapping the eag domain alone or the complete cytoplasmic N-terminal region. Functional analyses indicated that introduction of the homologous hERG1 eag domain led to both a fast phase and a slow phase of channel inactivation in the rEag1 chimeras. By contrast, the inactivation features were retained in the reverse hERG1 chimeras. Furthermore, an eag domain-lacking rEag1 deletion mutant also showed the fast phase of inactivation that was notably attenuated upon co-expression with the rEag1 eag domain fragment, but not with the hERG1 eag domain fragment. Additionally, we have identified a point mutation in the S4-S5 linker region of rEag1 that resulted in a similar inactivation phenotype. Biophysical analyses of these mutant constructs suggested that the inactivation gating of rEag1 was distinctly different from that of hERG1. Overall, our findings are consistent with the notion that the eag domain plays a critical role in regulating the inactivation gating of rEag1. We propose that the eag domain may destabilize or mask an inherent voltage-dependent inactivation of rEag1 K+ channels.


Asunto(s)
Canales de Potasio Éter-A-Go-Go/metabolismo , Activación del Canal Iónico/fisiología , Animales , Canales de Potasio Éter-A-Go-Go/química , Canales de Potasio Éter-A-Go-Go/genética , Femenino , Células HEK293 , Humanos , Ratones , Oocitos/fisiología , Técnicas de Placa-Clamp , Estructura Terciaria de Proteína , ARN Complementario/metabolismo , Ratas , Proteínas Recombinantes de Fusión/biosíntesis , Proteínas Recombinantes de Fusión/química , Proteínas Recombinantes de Fusión/genética , Transfección , Xenopus/crecimiento & desarrollo
10.
J Biol Chem ; 289(33): 22815-22834, 2014 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-25008323

RESUMEN

A functional voltage-gated K(+) (Kv) channel comprises four pore-forming α-subunits, and only members of the same Kv channel subfamily may co-assemble to form heterotetramers. The ether-à-go-go family of Kv channels (KCNH) encompasses three distinct subfamilies: Eag (Kv10), Erg (Kv11), and Elk (Kv12). Members of different ether-à-go-go subfamilies, such as Eag and Erg, fail to form heterotetramers. Although a short stretch of amino acid sequences in the distal C-terminal section has been implicated in subfamily-specific subunit assembly, it remains unclear whether this region serves as the sole and/or principal subfamily recognition domain for Eag and Erg. Here we aim to ascertain the structural basis underlying the subfamily specificity of ether-à-go-go channels by generating various chimeric constructs between rat Eag1 and human Erg subunits. Biochemical and electrophysiological characterizations of the subunit interaction properties of a series of different chimeric and truncation constructs over the C terminus suggested that the putative C-terminal recognition domain is dispensable for subfamily-specific assembly. Further chimeric analyses over the N terminus revealed that the N-terminal region may also harbor a subfamily recognition domain. Importantly, exchanging either the N-terminal or the C-terminal domain alone led to a virtual loss of the intersubfamily assembly boundary. By contrast, simultaneously swapping both recognition domains resulted in a reversal of subfamily specificity. Our observations are consistent with the notion that both the N-terminal and the C-terminal recognition domains are required to sustain the subfamily-specific assembly of rat Eag1 and human Erg.


Asunto(s)
Canales de Potasio Éter-A-Go-Go/metabolismo , Animales , Canales de Potasio Éter-A-Go-Go/genética , Células HEK293 , Humanos , Estructura Cuaternaria de Proteína , Estructura Terciaria de Proteína , Ratas , Xenopus laevis
11.
Chem Commun (Camb) ; 49(51): 5724-6, 2013 Jun 28.
Artículo en Inglés | MEDLINE | ID: mdl-23558426

RESUMEN

A moisture-triggered release system was developed using porous metal-organic materials as encapsulating agents. Release of both hydrophilic (ethyl butyrate) and hydrophobic (D-limonene) fragrance compounds was investigated by gas adsorption measurement, thermogravimetric analysis and gas chromatography-mass spectroscopy. These materials exhibit exceptional fragrance compatibility and controlled release compared to the current leading encapsulation technology.

12.
J Phys Condens Matter ; 24(42): 424203, 2012 Oct 24.
Artículo en Inglés | MEDLINE | ID: mdl-23032253

RESUMEN

The adsorption energies of small molecules in nanoporous materials are often determined by isotherm measurements. The nature of the interaction and the response of the host material, however, can best be studied by spectroscopic methods. We show here that infrared absorption and Raman spectroscopy measurements together with density functional theory calculations, utilizing the novel van der Waals density functional vdW-DF, constitute a powerful approach to studying the weak van der Waals interactions associated with the incorporation of small molecules in these materials. In particular, we show how vdW-DF assists the interpretation of the vibrational spectroscopy data to uncover the binding sites and energies of these molecules, including the subtle dependence on loading of the IR asymmetric stretch mode of CO(2) when adsorbed in MOF-74-Mg. To gain a better understanding of the adsorption mechanism of CO(2) in MOF-74-Mg, the results are compared with CO within MOF-74-Mg.


Asunto(s)
Dióxido de Carbono/química , Magnesio/química , Compuestos Organometálicos/química , Teoría Cuántica , Espectrofotometría Infrarroja , Espectrometría Raman , Interacciones Hidrofóbicas e Hidrofílicas , Propiedades de Superficie , Vibración
13.
J Am Chem Soc ; 134(37): 15201-4, 2012 Sep 19.
Artículo en Inglés | MEDLINE | ID: mdl-22946693

RESUMEN

Separation of hydrocarbons is one of the most energy demanding processes. The need to develop materials for the selective adsorption of hydrocarbons, under reasonable conditions, is therefore of paramount importance. This work unveils unexpected hydrocarbon selectivity in a flexible Metal-Organic Framework (MOF), based on differences in their gate opening pressure. We show selectivity dependence on both chain length and specific framework-gas interaction. By combining Raman spectroscopy and theoretical van der Waals Density Functional (vdW-DF) calculations, the separation mechanisms governing this unexpected gate-opening behavior are revealed.


Asunto(s)
Hidrocarburos/aislamiento & purificación , Metales/química , Compuestos Orgánicos/química , Adsorción , Espectrometría Raman
16.
Langmuir ; 27(23): 14169-79, 2011 Dec 06.
Artículo en Inglés | MEDLINE | ID: mdl-21973224

RESUMEN

The intriguing hysteretic adsorption-desorption behavior of certain microporous metal-organic frameworks (MMOFs) has received considerable attention and is often associated with a gate-opening (GO) effect. Here, the hysteretic adsorption of N(2) and Ar to Zn(2)(bpdc)(2)(bpee) (bpdc = 4,4'-biphenyldicarboxylate; bpee = 1,2-bipyridylethene) shows a pronounced effect of allowed experimental time at 77 and 87 K. When the time allowed is on the order of minutes for N(2) at 77 K, no adsorption is observed, whereas times in excess of 60 h is required to achieve appreciable adsorption up to a limiting total coverage. Given sufficient time, the total uptake for N(2) and Ar converged at similar reduced temperatures, but the adsorption of Ar was significantly more rapid than that of N(2), an observation that can be described by activated configurational diffusion. N(2) and Ar both exhibited discontinuous stepped adsorption isotherms with significant hysteresis, features that were dependent upon the allowed time. The uptake of H(2) at 77 K was greater than for both N(2) and Ar but showed no discontinuity in the isotherm, and hysteretic effects were much less pronounced. N(2) and Ar adsorption data can be described by an activated diffusion process, with characteristic times leading to activation energies of 6.7 and 12 kJ/mol. Fits of H(2) adsorption data led to activation energies in the range 2-7 kJ/mol at low coverage and nonactivated diffusion at higher coverage. An alternate concentration-dependent diffusion model is presented to describe the stepwise adsorption behavior, which is observed for N(2) and Ar but not for H(2). Equilibrium is approached very slowly for adsorption to molecularly sized pores at low temperature, and structural change (gate opening), although it may occur, is not required to explain the observations.


Asunto(s)
Argón/química , Hidrógeno/química , Nitrógeno/química , Compuestos Organometálicos/química , Temperatura , Adsorción , Cinética , Propiedades de Superficie , Factores de Tiempo
17.
J Am Chem Soc ; 133(32): 12849-57, 2011 Aug 17.
Artículo en Inglés | MEDLINE | ID: mdl-21736366

RESUMEN

The unusual uptake behavior and preferential adsorption of CO(2) over N(2) are investigated in a flexible metal-organic framework system, Zn(2)(bdc)(2)(bpee), where bpdc = 4,4'-biphenyl dicarboxylate and bpee = 1,2-bis(4-pyridyl)ethylene, using Raman and IR spectroscopy. The results indicate that the interaction of CO(2) with the framework induces a twisting of one of its ligands, which is possible because of the type of connectivity of the carboxylate end group of the ligand to the metal center and the specific interaction of CO(2) with the framework. The flexibility of the bpee pillars allows the structure to respond to the twisting, fostering the adsorption of more CO(2). DFT calculations support the qualitative picture derived from the experimental analysis. The adsorption sites at higher loading have been identified using a modified van der Waals-Density Functional Theory method, showing that the more energetically favorable positions for the CO(2) molecules are closer to the C═C bond of the bpee and the C-C bond of the bpdc ligands instead of the benzene and pyridine rings of these ligands. These findings are consistent with changes observed using Raman spectroscopy, which is useful for detecting both specific guest-host interactions and structural changes in the framework.

18.
J Transl Med ; 9: 82, 2011 May 28.
Artículo en Inglés | MEDLINE | ID: mdl-21619678

RESUMEN

BACKGROUND: Colorectal cancer (CRC) is the predominant gastrointestinal malignancy and the leading cause of cancer death. The identification of genes related to CRC is important for the development of successful therapies and earlier diagnosis. METHODS: Molecular analysis of feces was evaluated as a potential method for CRC detection. Expression of a predicted protein with unknown function, KIAA0247, was found in feces evaluated using specific quantitative real-time polymerase chain reaction. Its cellular function was then analyzed using immunofluorescent staining and the changes in the cell cycle in response to 5-fluorouracil (5-FU) were assessed. RESULTS: Gastrointestinal tissues and peripheral blood lymphocytes ubiquitously expressed KIAA0247. 56 CRC patients fell into two group categories according to fecal KIAA0247 mRNA expression levels. The group with higher fecal KIAA0247 (n=22; ≥0.4897) had a significantly greater five-year overall survival rate than the group with lower fecal KIAA0247 (n = 30; <0.4897) (66.0 ± 11.6%; p=0.035, log-rank test). Fecal expression of KIAA0247 inversely related to CRC tumor size (Kendall's tau-b=-0.202; p=0.047). Immunofluorescent staining revealed that the cytoplasm of CRC cells evenly expresses KIAA0247 without 5-FU treatment, and KIAA0247 accumulates in the nucleus after 40 µM 5-FU treatment. In HCT116 p53(-/-) cells, which lack p53 cell cycle control, the proportion of cells in the G2/M phase was larger (13%) in KIAA0247-silent cells than in the respective shLuc control (10%) and KIAA0247-overexpressing cells (7%) after the addition of low dose (40 µM) 5-FU. Expression of three cyclin genes (cyclin A2, cyclin B1, and cyclin B2) also downregulated in the cells overexpressing KIAA0247. CONCLUSIONS: This is the first description of a linkage between KIAA0247 and CRC. The study's data demonstrate overexpression of KIAA0247 associates with 5-FU therapeutic benefits, and also identify the clinical significance of fecal KIAA0247 in CRC.


Asunto(s)
Ciclo Celular/efectos de los fármacos , Neoplasias Colorrectales/tratamiento farmacológico , Neoplasias Colorrectales/patología , Proteínas del Sistema Complemento/metabolismo , Fluorouracilo/farmacología , Fluorouracilo/uso terapéutico , Anciano , División Celular/efectos de los fármacos , Colon/efectos de los fármacos , Colon/metabolismo , Colon/patología , Neoplasias Colorrectales/genética , Proteínas del Sistema Complemento/genética , Ciclinas/genética , Ciclinas/metabolismo , Heces , Femenino , Fase G2/efectos de los fármacos , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Células HCT116 , Humanos , Espacio Intracelular/efectos de los fármacos , Espacio Intracelular/metabolismo , Masculino , Proteínas de la Membrana , Transporte de Proteínas/efectos de los fármacos , ARN Mensajero/genética , ARN Mensajero/metabolismo , Análisis de Supervivencia
19.
J Am Chem Soc ; 133(13): 4782-4, 2011 Apr 06.
Artículo en Inglés | MEDLINE | ID: mdl-21401134

RESUMEN

The role of low binding energy sites on the adsorption of H(2) in metal-organic frameworks (MOFs) with unsaturated metal centers has not been identified. For instance, the importance of the benzene sites on H(2) adsorption at the metal site in MOF-74 has not been established. We report here experimental evidence that unambiguously shows that the internal mode of H(2) adsorbed at the metal site undergoes both a frequency shift and a marked change in its dynamic dipole moment when H(2) is adsorbed at the next nearest neighbor "benzene" site in MOF-74-Co. The effect of loading (i.e., occupation of all benzene sites) also induces spectroscopic shifts in H(2) at the metal site. These interactions highlight the role of lower binding energy sites in H(2) adsorption.


Asunto(s)
Derivados del Benceno/química , Cobalto/química , Hidrógeno/química , Compuestos Organometálicos/química , Adsorción , Propiedades de Superficie
20.
Chemistry ; 17(18): 5101-9, 2011 Apr 26.
Artículo en Inglés | MEDLINE | ID: mdl-21433121

RESUMEN

Hydroxyl- and amino- functionalized [Zn(BDC)(TED)(0.5)]·2DMF·0.2H(2)O leads to two new structures, [Zn(BDC-OH)(TED)(0.5)]·1.5DMF·0.3H(2)O and [Zn(BDC-NH(2))(TED)(0.5)]·xDMF·yH(2)O (BDC=terephthalic acid, TED=triethylenediamine, BDC-OH=2-hydroxylterephthalic acid, BDC-NH(2)=2-aminoterephthalic acid). Single-crystal X-ray diffraction and powder X-ray diffraction studies confirmed that the structures of both functionalized compounds are very similar to that of their parent structure. Compound [Zn(BDC)(TED)(0.5)]·2DMF·0.2H(2)O can be considered a 3D porous structure with three interlacing 1D channels, whereas both [Zn(BDC-OH)(TED)(0.5)]·1.5DMF·0.3H(2)O and [Zn(BDC-NH(2))(TED)(0.5)]·xDMF·yH(2)O contain only 1D open channels as a result of functionalization of the BDC ligand by the OH and NH(2) groups. A notable decrease in surface area and pore size is thus observed in both compounds. Consequently, [Zn(BDC)(TED)(0.5)]·2DMF·0.2H(2)O takes up the highest amount of H(2) at low temperatures. Interestingly, however, both [Zn(BDC-OH)(TED)(0.5)]·1.5DMF·0.3H(2)O and [Zn(BDC-NH(2))(TED)(0.5)]·xDMF·yH(2)O show significant enhancement in CO(2) uptake at room temperature, suggesting that the strong interactions between CO(2) and the functionalized ligands, indicating that surface chemistry, rather than porosity, plays a more important role in CO(2) adsorption. A comparison of single-component CO(2), CH(4), CO, N(2), and O(2) adsorption isotherms demonstrates that the adsorption selectivity of CO(2) over other small gases is considerably enhanced through functionalization of the frameworks. Infrared absorption spectroscopic measurements and theoretical calculations are also carried out to assess the effect of functional groups on CO(2) and H(2) adsorption potentials.


Asunto(s)
Dióxido de Carbono/farmacocinética , Modelos Moleculares , Compuestos Organometálicos/química , Ácidos Ftálicos/química , Zinc/química , Adsorción , Dióxido de Carbono/análisis , Cristalografía por Rayos X , Gases/química , Ligandos , Espectroscopía Infrarroja por Transformada de Fourier
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...