Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 35
Filtrar
1.
Mater Today Bio ; 11: 100125, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-34485892

RESUMEN

The engineering of advanced materials capable of mimicking the cellular micro-environment while providing cells with physicochemical cues is central for cell culture applications. In this regard, paper meets key requirements in terms of biocompatibility, hydrophilicity, porosity, mechanical strength, ease of physicochemical modifications, cost, and ease of large-scale production, to be used as a scaffold material for biomedical applications. Most notably, paper has demonstrated the potential to become an attractive alternative to conventional biomaterials for creating two-dimensional (2D) and three-dimensional (3D) biomimetic cell culture models that mimic the features of in vivo tissue environments for improving our understanding of cell behavior (e.g. growth, cell migration, proliferation, differentiation and tumor metastasis) in their natural state. On the other hand, integration of plasmonic nanomaterials (e.g. gold nanoparticles) within the fibrous structure of paper opens the possibility to generate multifunctional scaffolds equipped with biosensing tools for monitoring different cell cues through physicochemical signals. Among different plasmonic based detection techniques, surface-enhanced Raman scattering (SERS) spectroscopy emerged as a highly specific and sensitive optical tool for its extraordinary sensitivity and the ability for multidimensional and accurate molecular identification. Thus, paper-based plasmonic substrates in combination with SERS optical detection represent a powerful future platform for monitoring cell cues during cell culture processes. To this end, in this review, we will describe the different methods for fabricating hybrid paper-plasmonic nanoparticle substrates and their use in combination with SERS spectroscopy for biosensing and, more specifically, in cell culture applications.

2.
Nanoscale ; 9(24): 8157-8163, 2017 Jun 22.
Artículo en Inglés | MEDLINE | ID: mdl-28581015

RESUMEN

Silicon nanoparticles are unique materials with applications in a variety of fields, from electronics to catalysis and biomedical uses. Despite technological advancements in nanofabrication, the development of a simple and inexpensive route for the synthesis of homogeneous silicon nanoparticles remains highly challenging. Herein, we describe a new, simple and inexpensive colloidal synthetic method for the preparation, under normal pressure and mild temperature conditions, of relatively homogeneous spherical silicon nanoparticles of either ca. 4 or 6 nm diameter. The key features of this method are the selection of a eutectic salt mixture as a solvent, the identification of appropriate silicon alkoxide precursors, and the unconventional use of alkali earth metals as shape-controlling agents.

3.
Rev. chil. cir ; 69(3): 268-272, jun. 2017.
Artículo en Español | LILACS | ID: biblio-844372

RESUMEN

Introducción: Se estima que del total de los cánceres, el 5-10% tendría una base genética. Actualmente es posible identificar a los individuos con predisposición genética en algunos cánceres como manera de intervenir precozmente en el desarrollo de esta enfermedad. Objetivos: Evaluar la utilidad de la cirugía profiláctica en el cáncer medular de tiroides hereditario. Material y métodos: Este trabajo es una revisión de literatura de diferentes estudios extraídos de bibliotecas electrónicas como Scientific Electronic Library Online (SciELO), MedLine-PubMed y UpToDate, mediante la construcción de preguntas clínicas y términos MeSH enfocados principalmente en la búsqueda específica de información sobre el cáncer medular de tiroides hereditario. Resultados: Los estudios revisados demuestran que la tiroidectomía profiláctica con resección linfática cervical representa el único tratamiento eficaz en el caso del cáncer medular de tiroides hereditario. Conclusiones: La cirugía profiláctica ha demostrado una importante disminución del riesgo de cáncer de tiroides y se considera una conducta de rigor en portadores del gen RET en el cáncer medular de tiroides.


Introduction: Approximately 5-10% of global cancer has a genetic base. Nowadays it is possible to identify those who have a genetic predisposition for some cancers, so they can be treated in short term. Objectives: Evaluate how useful is prophylactic surgery on hereditary Medullary Thyroid Cancer. Materials and methods: This investigation is a literature review of different research papers from electronic databases such as Scientific Electronic Library Online (SciELO), MedLine-PubMed and UpToDate. The research was made with clinical queries and MeSH terms, specially focused on hereditary Medullary Thyroid Cancer. Results: This research shows that prophylactic Thyroidectomy with cervical lymph node resection is the only effective and curative treatment for hereditary Medullary Thyroid Cancer. Conclusions: Prophylactic surgery has proof an important role decreasing the risk on Hereditary Thyroid cancer Syndrome and in RET carriers surgery is considered a must.


Asunto(s)
Humanos , Carcinoma Medular/congénito , Carcinoma Medular/cirugía , Neoplasias de la Tiroides/cirugía , Tiroidectomía/métodos , Carcinoma Medular/prevención & control , Procedimientos Quirúrgicos Profilácticos , Neoplasias de la Tiroides/prevención & control
4.
Nanoscale ; 9(15): 5020, 2017 04 13.
Artículo en Inglés | MEDLINE | ID: mdl-28368428

RESUMEN

Correction for 'A study of the depth and size of concave cube Au nanoparticles as highly sensitive SERS probes' by J. M. Romo-Herrera et al., Nanoscale, 2016, 8, 7326-7333.

5.
Nanoscale ; 9(17): 5725-5736, 2017 May 04.
Artículo en Inglés | MEDLINE | ID: mdl-28426077

RESUMEN

Raspberry-like nano-objects made of large plasmonic satellites (>10 nm) covering a central dielectric particle have many potential applications as photonic materials, superlenses and (bio-) sensors, but their synthesis remains challenging. Herein, we show how to build stable and robust raspberry-like nano-systems with close-packed satellites, by combining monodisperse silica particles (80 or 100 nm diameter) and oppositely charged noble metal nanoparticles (Au or Ag) with well-defined sizes (10-50 nm). The spectral characteristics of their associated plasmonic resonances (wavelength, linewidth, extinction cross-section) and the electromagnetic coupling between satellites were observed using the spatial modulation spectroscopy technique and interpreted through a numerical model. The composite nano-objects exhibit numerous hot spots at satellite junctions, resulting in excellent surface-enhanced Raman scattering (SERS) performance. The SERS efficiency of the raspberry-like clusters is highly dependent on their structure.

6.
Analyst ; 141(17): 5170-80, 2016 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-27213770

RESUMEN

Ultrasensitive direct SERS analysis offers a powerful analytical tool for the structural characterization and classification of nucleic acids. However, acquisition of reliable spectral fingerprints of such complex biomolecules poses important challenges. In recent years, many efforts have been devoted to overcome these limitations, mainly implementing silver colloids as plasmonic substrates. However, a reliable cross-comparison of results reported in the recent literature is extremely hard to achieve, mostly due to the broad set of different surface properties of the plasmonic nanoparticles. Herein, we perform a thorough investigation of the role played by the metal/liquid interface composition of silver colloids in the direct label-free SERS analysis of DNA. Target molecules of increasing complexity, from short homopolymeric strands to long genomic duplexes, were used as probes. We demonstrate how apparently subtle changes in the colloidal surface chemistry can dramatically modify the affinity and the final SERS spectral profile of DNA. This has significant implications for the future design of new analytical strategies for the detection of DNA using SERS without labels.


Asunto(s)
Coloides , ADN/análisis , Nanopartículas del Metal , Plata , Espectrometría Raman
7.
Nanoscale ; 8(13): 7326-33, 2016 Apr 07.
Artículo en Inglés | MEDLINE | ID: mdl-26979125

RESUMEN

High and uniform near fields are localized at the eight similar sharp corners of cubic gold nanoparticles. Moreover, by introducing concavity in the particle lateral planes, such field intensities can be further increased and tuned in the near infrared region without altering the overall size of the nanoparticles. Herein, we perform a thorough investigation of the morphological, crystallographic and plasmonic properties of concave gold nanocubes (GNCs) in the sub-70 nm size range, for their potential application as highly efficient SERS substrates in size-limiting cases. Theoretical calculations indicate that the highest increment of the near-field is located at the eight sharp tips and, interestingly, a medium near-field increment is also activated over the volume next to the concave surface. Remarkably, the plasmonic response of the concave cubic morphology showed great sensitivity to the concavity degree. Experimental SERS analysis nicely matches the outcome of the theoretical model, confirming that medium-sized concave GNCs (35 nm side length) possess the highest SERS activity upon excitation with a 633 nm laser, whereas larger 61 nm side concave GNCs dominate the optical response at 785 nm. Due to their size-intensity trade off, we envision that such small concave gold nanocubes can provide a highly active and efficient SERS platform for size-limiting applications, especially when near infrared excitations are required.

8.
Rev. ANACEM (Impresa) ; 10(1): 39-43, 20160124. tab, ilus
Artículo en Español | LILACS | ID: biblio-1291233

RESUMEN

Introducción: El daño hepático por fármacos es una lesión secundaria al uso de medicamentos. Posee una baja incidencia, representando la causa más común de muerte por falla hepática aguda. Es importante el diagnóstico y tratamiento precoz para evitar resultados desfavorables. Presentación del caso: Mujer de 73 años, con antecedentes de Hipertensión arterial en tratamiento, colecistectomizada; cursó neumonía adquirida en la comunidad de presentación atípica en tratamiento con claritromicina 500mg/12 horas y al cuarto día de tratamiento presentó ictericia, coluria, hipocolia y astenia. Al examen físico presentó dolor a palpación en hemiabdomen derecho y hepatomegalia. Los exámenes en urgencias mostraron una marcada alteración de las pruebas hepáticas, con leucocitos de 9.020/mm3 y 8% de eosinófilos. Se solicitó ecotomografía abdominal que no evidenció obstrucción de vía biliar. Durante la hospitalización se descartó serología para Virus Hepatitis A, B, C, Epstein Barr, Citomegalovirus y Virus de la Inmunodeficiancia Humana (VIH), junto con un perfil inmunológico no patológico. Se complementó con colangioresonancia que no evidenció obstrucción de la vía biliar, por lo que se indicó biopsia hepática que concluyó "daño hepático secundario a fármacos''. Se suspendió claritromicina, evolucionando favorablemente dándose de alta al séptimo día. Discusión: La claritromicina es un antibiótico usado ampliamente para tratar las infecciones bacterianas, sin embargo, es capaz de inducir daño hepático. El diagnóstico del daño hepático por fármacos es difícil, requiriéndose alto índice de sospecha, en donde las manifestaciones clínicas, la eosinofilia y el descarte de otras patologías son fundamentales para plantear el diagnóstico.


Introduction: Drug induced liver injury (DILI), is a drug hepatotoxicity, with low incidence. However represents the most common cause of death secondary to acute liver failure. Assertive diagnosis and early treatment is important to avoid adverse results. Case report: A 73-year-old woman, with arterial hypertension and cholecystectomy, who suffered community acquired pneumonia with atypical presentation, was treated with clarithromycin 500 mg twice a day. She manifested jaundice, choluria, hipocholia and fatigue after the fourth day in treatment. Additional, physical examination: at palpation showed right and upper abdominal pain, and hepatomegaly. During the emergency room, laboratory tests showed significant alterations in liver function. Total leukocyte count 9020 with 8% eosinophils. Abdominal ultrasound was negative for biliary obstruction. During hospitalization, markers for autoimmune liver disease were non pathological, and viral serologies (Hepatitis A, B, C viruses, Epstein Barr, Cytomegalovirus and Human immunodeficiency virus) were negative. Biliary obstruction was negative according Magnetic resonance cholangiopancreatography. Liver biopsy showed "drug induced liver injury". Clarithromycin was suspended, and the patient achieved clinical improvement and she was discharge at the 7th day. Discussion: Clarithromycin is an antibiotic widely used for several bacterial infections, capable of induced hepatotoxicity. Diagnosis of DILI is difficult, that requires high index of clinical suspicion. Clinical manifestations, eosinophilia and diferential diagnoses are key for an assertive diagnosis


Asunto(s)
Humanos , Femenino , Anciano , Claritromicina/efectos adversos , Enfermedad Hepática Inducida por Sustancias y Drogas/etiología , Enfermedad Hepática Inducida por Sustancias y Drogas/diagnóstico por imagen , Fallo Hepático/etiología , Lesión Renal Aguda/etiología , Antibacterianos/efectos adversos
9.
Phys Med Biol ; 60(1): 375-401, 2015 Jan 07.
Artículo en Inglés | MEDLINE | ID: mdl-25503853

RESUMEN

A procedure to characterize beams of a medical linear accelerator for their use in Monte Carlo (MC) dose calculations for intraoperative electron radiation therapy (IOERT) is presented. The procedure relies on dose measurements in homogeneous media as input, avoiding the need for detailed simulations of the accelerator head. An iterative algorithm (EM-ML) has been employed to extract the relevant details of the phase space (PHSP) of the particles coming from the accelerator, such as energy spectra, spatial distribution and angle of emission of particles. The algorithm can use pre-computed dose volumes in water and/or air, so that the machine-specific tuning with actual data can be performed in a few minutes. To test the procedure, MC simulations of a linear accelerator with typical IOERT applicators and energies, have been performed and taken as reference. A solution PHSP derived from the dose produced by the simulated accelerator has been compared to the reference PHSP. Further, dose delivered by the simulated accelerator for setups not included in the fit of the PHSP were compared to the ones derived from the solution PHSP. The results show that it is possible to derive from dose measurements PHSP accurate for IOERT MC dose estimations.


Asunto(s)
Algoritmos , Huesos/efectos de la radiación , Electrones/uso terapéutico , Cuidados Intraoperatorios , Pulmón/efectos de la radiación , Planificación de la Radioterapia Asistida por Computador/métodos , Simulación por Computador , Estudios de Factibilidad , Humanos , Método de Montecarlo , Aceleradores de Partículas , Fantasmas de Imagen , Dosificación Radioterapéutica
10.
Nanoscale ; 6(11): 5666-70, 2014 Jun 07.
Artículo en Inglés | MEDLINE | ID: mdl-24764023

RESUMEN

In this communication we demonstrate the large amplification values of the Raman signal of organic molecules attached to silicon nanoparticles (SiNPs). Light induced Mie resonances of high refractive index particles generate strong evanescent electromagnetic (EM) fields, thus boosting the Raman signal of species attached to the nanoparticles. The interest of this process is justified by the wide range of experimental configurations that can be implemented including photonic crystals, the sharp spectral resonances easily tuneable with the particle size, the biocompatibility and biodegradability of silicon, and the possibility of direct analysis of molecules that do not contain functional groups with high affinity for gold and silver. Additionally, silicon nanoparticles present stronger field enhancement due to Mie resonances at larger sizes than gold.

11.
Rev Clin Esp ; 208(3): 135-7, 2008 Mar.
Artículo en Español | MEDLINE | ID: mdl-18275767

RESUMEN

OBJECTIVES: The recommended treatment in patients with primary antiphospholipid syndrome (APS) after a thrombotic event is long-term anticoagulation. However, it is still not exactly known how to manage patients who remain stable for years and whose antiphospholipid antibodies (APA) decrease until becoming negative. This study aims to assess the course of the primary APS in a group of patients after anticoagulation therapy is discontinued. PATIENTS AND METHOD: Ten patients with primary APS who had developed deep venous thrombosis in the limbs (9) or in the aorta (1) were included. After a minimum period of 12 months of anticoagulation therapy, this was discontinued if the patients were negative APA during the follow-up in two consecutive measurements. RESULTS: Six patients (60%) developed persistent negative APA. Four had transient risk factors (2 pregnant, 1 immobilization, 2 oral contraceptives). No new thrombosis episode was observed after a follow-up period of 21 +/- 4.9 months. CONCLUSIONS: Our data suggest that anticoagulation can be discontinued in those patients with primary APS and persistent negative APA, especially if the thrombotic event was venous and occurred in association with a transient risk factor, such as immobilization or pregnancy. Extensive studies are required to confirm these results.


Asunto(s)
Acenocumarol/uso terapéutico , Anticoagulantes/uso terapéutico , Síndrome Antifosfolípido/complicaciones , Heparina de Bajo-Peso-Molecular/uso terapéutico , Trombosis de la Vena/complicaciones , Trombosis de la Vena/tratamiento farmacológico , Adulto , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos
12.
Rev. clín. esp. (Ed. impr.) ; 208(3): 135-137, mar. 2008. tab
Artículo en Es | IBECS | ID: ibc-63879

RESUMEN

Objetivos. La anticoagulación a largo plazo es el tratamiento recomendado en el síndrome antifosfolípido primario (SAF) tras un evento trombótico. Sin embargo, no se conoce con precisión cómo se deben manejar los enfermos que permanecen estables durante años, y cuos anticuerpos antifosfolípido (AAF) descienden hasta negativizarse. El objetivo de este trabajo es valorar la evolución del SAF primario, tras la suspensión de la anticoagulación, en este grupo de pacientes. Población y métodos. Se incluyeron diez pacientes diagnosticados de SAF primario que habían sufrido una trombosis venosa profunda en las extremidades (9) y en la aorta(1). Tras un período mínimo de 12 meses de anticoagulación se retiró el tratamiento a los pacientes que presentaron AAF negativos a lo largo del seguimiento en dos determinaciones consecutivas. Resultados. Los AAF se negativizaron de forma persistente en seis enfermos (60%). Cuatro presentaban factores de riesgo transitorios (2 gestación, 1 inmovilización, 2 anticonceptivos), y tras la retirada de la coagulación ninguno desarrolló nuevos eventos trombóticos. Conclusiones. Nuestros datos sugieren que la retirada del tratamiento anticoagulante puede ser adecuada en un grupo de pacientes con SAF primario que, tras un periodo prolongado de anticoagulación, negativizan los AAF de forma estable. Esta actitud sería más segura si el evento trombótico era venoso y ocurrió durante la presencia de un factor de riesgo transitorio. No obstante, son necesarios estudios más amplios que confirmen estos hallazgos


Objectives. The recommended treatment in patients with primary antiphospholipid syndrome (APS) after a thrombotic event is long-term anticoagulation. However, it is still not exactly known how to manage patients who remain stable for years and whose antiphospholipid antibodies (APA) decrease until becoming negative. This study aims to assess the course of the primary APS in a group of patients after anticoagulation therapy is discontinued. Patients and method. Ten patients with primary APS who had developed deep venous thrombosis in the limbs (9) or in the aorta (1) were included. After a minimum period of 12 months of anticoagulation therapy, this was discontinued if the patients were negative APA during the follow-up in two consecutive measurements. Results. Six patients (60%) developed persistent negative APA. Four had transient risk factors (2 pregnant, 1 immobilization, 2 oral contraceptives). No new thrombosis episode was observed after a follow-up period of 21 ± 4.9 months. Conclusions. Our data suggest that anticoagulation can be discontinued in those patients with primary APS and persistent negative APA, especially if the thrombotic event was venous and occurred in association with a transient risk factor, such as immobilization or pregnancy. Extensive studies are required to confirm these results


Asunto(s)
Humanos , Síndrome Antifosfolípido/tratamiento farmacológico , Anticoagulantes/administración & dosificación , Anticuerpos Anticardiolipina/análisis , Trombosis/tratamiento farmacológico , Trombosis/etiología , Factores de Riesgo
13.
Br J Nutr ; 99(4): 699-702, 2008 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-17903340

RESUMEN

The objective of the study was to determine whether Plasminogen Activator Inhibitor Type 1 (PAI-1) -675 4G/5G polymorphism is associated with the response of functional plasma PAI-1 concentrations to changes in the amount and quality of dietary fat in healthy subjects. PAI-1 is the major inhibitor of fibrinolysis, and a lower level of fibrinolytic activity could be implicated in an increased risk of IHD. Fifty-nine healthy Spanish volunteers (ten 4G/4G homozygotes, twenty-eight heterozygotes 4G/5G and twenty-one 5G/5G homozygotes) consumed three diets for periods of 4 weeks each: a SFA-rich diet (38 % fat, 20 % SFA), followed by a carbohydrate-rich diet (30 % fat, 55 % carbohydrate) and a MUFA-rich diet (38 % fat, 22 % MUFA) according to a randomized crossover design. At the end of each dietary period plasma lipid and functional plasma PAI-1 concentrations were determined. Subjects carrying the 4G allele (4G/4G and 4G/5G) showed a significant decrease in PAI-1 concentrations after the MUFA diet, compared with the SFA-rich and carbohydrate-rich diets (genotype x diet interaction: P = 0.028). 5G/5G homozygotes had the lowest plasma PAI-1 concentrations compared with 4G/4G and 4G/5G subjects (genotype: P = 0.002), without any changes as a result of the amount and the quality of the dietary fat. In summary, no differences in plasma PAI-1 concentration response were found after changes in dietary fat intake in 5G/5G homozygotes, although these subjects displayed the lowest concentrations of PAI-1. On the other hand, carriers of the 4G allele are more likely to hyper-respond to the presence of MUFA in the diet because of a greater decrease in PAI-1 concentrations.


Asunto(s)
Grasas de la Dieta/administración & dosificación , Inhibidor 1 de Activador Plasminogénico/sangre , Inhibidor 1 de Activador Plasminogénico/genética , Polimorfismo Genético , Adulto , Análisis de Varianza , Enfermedades Cardiovasculares/prevención & control , Estudios Cruzados , Carbohidratos de la Dieta/administración & dosificación , Ácidos Grasos Monoinsaturados/administración & dosificación , Ácidos Grasos Volátiles/administración & dosificación , Femenino , Fibrinólisis , Genotipo , Heterocigoto , Homocigoto , Humanos , Lípidos/sangre , Masculino , Periodo Posprandial
14.
J Hazard Mater ; 135(1-3): 122-8, 2006 Jul 31.
Artículo en Inglés | MEDLINE | ID: mdl-16387430

RESUMEN

In this work, the retention of cobalt on a humin (HU) derived from a brown coal is studied. Through a systematic and coordinated investigation of the behavior of the metal ions in solution (speciation diagrams as a function of pH) and their adsorption and precipitation processes with reactive functional groups of the solid (sorption isotherms), the interactions of different Co(II) species with HU are probed. To further confirm the nature of these interactions, the complementary spectroscopic techniques of FTIR, Raman microspectroscopy, UV-visible absorption and XRD are employed. Molecular modeling techniques are used to gain information about the stability of different Co(II) species as a function of pH, as well as the stability of Co(II) species complexed with benzoic acid, a common surface component of humic substances. It is found that the selectivity that humin has for different Co(II) species, as well as the amount of Co(II) that it can retain, are both highly dependent on pH. Through Raman microspectroscopy measurements, the presence and location of Co(OH)(2) precipitates on the surface of HU is confirmed.


Asunto(s)
Carbón Mineral , Cobalto/química , Sustancias Húmicas , Adsorción , Color , Electrones , Concentración de Iones de Hidrógeno , Hidroxilación , Modelos Moleculares , Conformación Molecular , Análisis Espectral
15.
Sci Total Environ ; 358(1-3): 243-54, 2006 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-15922408

RESUMEN

The ubiquitous presence of humic substances (HS), combined with their ability to provide multiple sites for chemical reaction, makes them relevant to numerous biogeochemical processes such as mineral weathering, nutrient bioavailability, and contaminant transport. The reactivity of HS depends on their functional group chemistry and microstructure, which are in turn influenced by the composition of the surrounding media. In order to help towards an understanding of structure conformations and aggregation process of HS in soils and waters and to get a better knowledge of these kinds of materials, a fulvic acid (FA) has been modelled as a function of its ionic state under different conditions. Our proposed theoretical model based on the Temple-Northeastern-Birmingham (TNB) monomer fits well with experimental observations on the solubility (dipolar moment) and electronic and vibrational spectra of FAs. The presence of water molecules has a great stabilization effect on the electrostatic energy; this effect is greater as ionized rate increases. In vacuum, the non-ionized aggregated species are more stable than monomers because of the increase in their interaction due to H-bonding and non-bonding forces. When the molecules are ionized, no aggregation process takes place. In solution, the FA concentration is a critical factor for the aggregation. The system containing two FA molecules probably did not form aggregates because its equivalent concentration was too low. When the concentration was increased, the system gave rise to the formation of aggregates. The ionic state is another critical factor in the aggregation process. The ionized FA has a higher electric negative charge, which increases the energetic barriers and inhibits the approximation of FA caused by the Brownian movement.


Asunto(s)
Sustancias Húmicas , Modelos Teóricos , Animales , Benzopiranos/química , Disponibilidad Biológica , Humanos , Suelo , Solubilidad , Agua/química
16.
Adv Colloid Interface Sci ; 116(1-3): 45-61, 2005 Nov 30.
Artículo en Inglés | MEDLINE | ID: mdl-16213453

RESUMEN

Surface-enhanced Raman scattering combines extremely high sensitivity, due to enhanced Raman cross-sections comparable or even better than fluorescence, with the observation of vibrational spectra of adsorbed species, providing one of the most incisive analytical methods for chemical and biochemical detection and analysis. SERS spectra are observed from a molecule-nanostructure enhancing system. This symbiosis molecule-nanostructure is a fertile ground for theoretical developments and a realm of applications from single molecule detection to biomedical diagnostic and techniques for nanostructure characterization.


Asunto(s)
Coloides/química , Nanoestructuras/química , Espectrometría Raman/métodos , Estructura Molecular , Tamaño de la Partícula , Dispersión de Radiación , Sensibilidad y Especificidad , Propiedades de Superficie
17.
Lipids ; 40(5): 471-6, 2005 May.
Artículo en Inglés | MEDLINE | ID: mdl-16094856

RESUMEN

Paraoxonase 1 (PON 1) is an esterase with antioxidant properties that is present in HDL. Gln192Arg polymorphism (also named Q192R or Q/R) of the PON 1 gene that encodes this protein defines two alleles (Q and R). The R allele has been associated with higher cardiovascular risk. LDL size and susceptibility to oxidation also have been identified as cardiovascular risk factors. Our objective was to determine whether genetic variations in the Gln192Arg polymorphism influence LDL size and susceptibility to oxidation after the consumption of diets with different fat content. In our experiments, the participants (n = 98) underwent three 4-wk diets--one, saturated fat-enriched (SAT); another, monounsaturated fat-enriched (MONO); and a third, carbohydrate-enriched (CHO). We observed that LDL were smaller in the QQ group after the CHO diet vs. the SAT (P < 0.01) and MONO diets (P < 0.03). No differences in LDL size were found in QR/RR subjects. When we analyzed lag time of oxidation of LDL, we found that when carriers of the R allele (QR/RR) received the MONO diet, the lag period of LDL oxidation was longer as compared with the CHO diet. Otherwise, we found no differences in QQ homozygotes when we evaluated the lag time of oxidation of LDL after the three diets. These results suggest that the Glnl92Arg polymorphism of the paraoxonase gene influences LDL size and susceptibility to oxidation in response to diet.


Asunto(s)
Arildialquilfosfatasa/genética , Carbohidratos de la Dieta/administración & dosificación , Lipoproteínas LDL/sangre , Adolescente , Adulto , Sustitución de Aminoácidos , Arginina/genética , Grasas de la Dieta/administración & dosificación , Grasas Insaturadas en la Dieta/administración & dosificación , Femenino , Glutamina/genética , Homocigoto , Humanos , Masculino , Persona de Mediana Edad , Polimorfismo Genético
18.
Chemosphere ; 59(5): 659-67, 2005 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-15792663

RESUMEN

Gray humic acids have a marked colloidal character, a large number of surface functional groups, and are subject to aggregation phenomena. They are able to complex soluble pollutants, and initiate flocculation processes as a function of environmental conditions. The aim of this work is to study the aggregation of a gray humic acid, which is stable in colloidal dispersion, by means of photon correlation spectroscopy, and molecular modeling. The effect of this aggregation in the solid state is also studied by means of N2 (to 77 K) and CO2 (to 273 K) adsorption isotherms, as well as FT-IR absorption. The variation of the colloid's zeta potential and size, with pH, reflects the ionization of the carboxylic and phenolic acidic groups, and a linear dependence of size on zeta potential. The decrease in the size of the colloids seems to be more affected by the ionization of the phenolic acid groups, than by that of the carboxylic acid groups, which is likely because in the case of the ionized carboxylic groups the humic colloids are still capable of generating H-bonds. In the solid state, aggregation effects are illustrated by a decrease in surface area, and a disappearance of certain micropores, with increasing pH. These features are likely due to an inhibition of aggregation in the colloidal state as a consequence of the increase in charge that results from ionization of the acidic groups, and also to an increased hindrance to H-bond formation, due to the loss of protons during the above-mentioned ionization process.


Asunto(s)
Floculación , Sustancias Húmicas , Concentración de Iones de Hidrógeno , Adsorción , Dióxido de Carbono/química , Coloides/química , Electroquímica , Modelos Moleculares , Nitrógeno/química , Tamaño de la Partícula , Porosidad , Espectroscopía Infrarroja por Transformada de Fourier
19.
Diabet Med ; 22(12): 1647-56, 2005 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-16401307

RESUMEN

AIMS: To investigate the role of HMG-CoA reductase inhibitor (statin) treatment during serum glucose variations on plasma oxidized LDL (ox-LDL) levels in obese patients with early Type 2 diabetes mellitus (T2D) and its relationship to endothelial biomarkers. METHODS: In a double-blind, randomized crossover study, 15 obese diet-treated T2D patients received cerivastatin (0.4 mg/day) or placebo for 3 months. Circulating ox-LDL levels were measured fasting and during a euglycaemic-hyperinsulinaemic clamp (approximately 5.5 mmol/l; EHC) and a hyperglycemic clamp (approximately 20 mmol/l; HC). An endothelium-dependent flow-mediated dilation (FMD) study was carried out and urinary albumin excretion (UAE) was measured at rest and during EHC. S-ICAM, s-VCAM and basal prothrombotic factors were also measured. RESULTS: During cerivastatin treatment, basal circulating ox-LDL levels decreased by 48% (P<0.001) compared with placebo. Serum ox-LDL levels decreased during EHC and remained unchanged during HC compared with the fasting state; with cerivastatin treatment these levels were lower compared with placebo both in the fasting state and during the clamp studies. FMD was higher with cerivastatin than with placebo (P<0.001) and the increments in FMD correlated with decrements in serum ox-LDL levels (r=0.78, P=0.001). Microalbuminuria increased during EHC but this was blunted during cerivastatin therapy compared with placebo (P<0.05). Basal sICAM-1 and sVCAM-1 levels decreased (P<0.01 and P<0.05, respectively). CONCLUSIONS: In early obese Type 2 diabetic patients, serum ox-LDL levels are influenced by short-term serum glucose variations and lowered with cerivastatin therapy. During cerivastatin treatment, improved flow-mediated endothelium-dependent dilation was associated with decrements in circulating ox-LDL levels and the hyperinsulinaemia-induced urinary albumin excretion was blunted.


Asunto(s)
Glucemia/metabolismo , Diabetes Mellitus Tipo 2/sangre , Inhibidores de Hidroximetilglutaril-CoA Reductasas/uso terapéutico , Lipoproteínas LDL/sangre , Piridinas/uso terapéutico , Adulto , Anciano , Albuminuria/tratamiento farmacológico , Albuminuria/metabolismo , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Método Doble Ciego , Endotelio Vascular/efectos de los fármacos , Femenino , Humanos , Lipoproteínas LDL/efectos de los fármacos , Masculino , Persona de Mediana Edad , Vasodilatación/efectos de los fármacos
20.
Analyst ; 129(12): 1251-6, 2004 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-15565227

RESUMEN

The results of the search for the optimal experimental conditions for ultrasentitive chemical analysis of 1-naphthalenethiol (1-NAT) and 2-naphthalenethiol (2-NAT) using surface-enhanced Raman scattering (SERS) are discussed. The report begins with a review of the vibrational spectra, including infrared and Raman spectra of the target molecules, and the interpretation of the observed frequencies aided by local density functional theory (DFT) calculations at the B3LYP/6-311G(d,p) level of theory. Several metal nanostructures were tested for SERS activity, including island films and colloids of silver, gold and copper. Correspondingly, the most effective laser line for excitation in the visible and near infrared region was sought. The achieved detection limit for 1-naphthalenethiol, and for 2-naphthalenethiol, on silver nanostructures is in the zeptomole regime.


Asunto(s)
Naftalenos/análisis , Espectrometría Raman/métodos , Compuestos de Sulfhidrilo/análisis , Tensoactivos/análisis , Nanotecnología , Espectrofotometría Infrarroja
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...