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1.
Sci Rep ; 12(1): 3541, 2022 03 03.
Artículo en Inglés | MEDLINE | ID: mdl-35241772

RESUMEN

Little attention has been given to the development of remediation strategies for soils polluted with mixture of pollution (metal(loid)s and organic compounds). The present study evaluates the effectiveness of different types of commercial iron nanoparticles (nanoscale zero valent iron (nZVI), bimetallic nZVI-Pd, and nano-magnetite (nFe3O4)), for the remediation of an industrial soil co-contaminated with Cr and PCBs. Soil samples were mixed with nZVI, nZVI-Pd, or nFe3O4 at doses selected according to their reactivity with PCBs, homogenized, saturated with water and incubated at controlled conditions for 15, 45 and 70 days. For each sampling time, PCBs and chromium were analyzed in aqueous and soil fractions. Cr(VI) and Cr leachability (TCLP test) were determined in the soil samples. The treatment with the three types of iron nanoparticles showed significant reduction in Cr concentration in aqueous extracts at the three sampling times (> 98%), compared to the control samples. The leachability of Cr in treated soil samples also decreased and was stable throughout the experiment. Results suggested that nZVI and nZVI-Pd immobilized Cr through adsorption of Cr(VI) on the shell and reduction to Cr(III). The mechanism of interaction of nFe3O4 and Cr(VI) included adsorption and reduction although its reducing character was lower than those of ZVI nanoparticles. PCBs significantly decreased in soil samples (up to 68%), after 15 days of treatment with the three types of nanoparticles. However, nFe3O4 evidenced reversible adsorption of PCBs after 45 days. In general, nZVI-Pd reduced PCB concentration in soil faster than nZVI. Control soils showed a similar reduction in PCBs concentration as those obtained with nZVI and nZVI-Pd after a longer time (45 days). This is likely due to natural bioremediation, although it was not effective for Cr remediation. Results suggest that the addition of nZVI or nZVI-Pd and pseudo-anaerobic conditions could be used for the recovery of soil co-contaminated with Cr and PCBs.


Asunto(s)
Restauración y Remediación Ambiental , Nanopartículas , Bifenilos Policlorados , Contaminantes del Suelo , Contaminantes Químicos del Agua , Cromo/análisis , Hierro , Suelo , Contaminantes del Suelo/análisis , Agua , Contaminantes Químicos del Agua/análisis
2.
Materials (Basel) ; 13(6)2020 Mar 20.
Artículo en Inglés | MEDLINE | ID: mdl-32245138

RESUMEN

The use of narrow titanium dental implants (NDI) for small ridges, reduced interdental space, or missing lateral incisors can be a viable option when compared to the conventional wider dental implants. Furthermore, in many cases, standard diameter implant placement may not be possible without grafting procedures, which increases the healing time, cost, and morbidity. The aim of this study was to analyze the mechanical viability of the current narrow implants and how narrow implants can be improved. Different commercially available implants (n = 150) were tested to determine maximum strength, strain to fracture, microhardness, residual stress, and fatigue obtaining the stress-number of cycles to fracture (SN) curve. Fractography was studied by scanning electron microscopy. The results showed that when the titanium was hardened by the addition of 15% of Zr or 12% cold worked, the fatigue limit was higher than the commercially pure grade 4 Ti without hardening treatment. Grade 4 titanium without hardening treatment in narrow dental implants can present fractures by fatigue. These narrow implants are subjected to high mechanical stresses and the mechanical properties of titanium do not meet the minimal requirements, which lead to frequent fractures. New hardening treatments allow for the mechanical limitations of conventional narrow implants to be overcome in dynamic conditions. These hardening treatments allow for the design of narrow dental implants with enhanced fatigue life and long-term behavior.

3.
J Mater Sci Mater Med ; 30(8): 90, 2019 Jul 25.
Artículo en Inglés | MEDLINE | ID: mdl-31346767

RESUMEN

The aim of this study was to evaluate the biomechanical behavior of Bone Level dental implants with four different neck designs in contact with cortical bone. Numerical simulations were performed using a Finite Element Method (FEM) based-model. In order to verify the FEM model, the in silico results were compared with the results obtained from histological analysis performed in an in vivo study with New Zealand rabbits. FEM was performed using a computerized 3D model of Bone Level dental implants inserted in the lower jaw bone with an applied axial load of 100 N. The analysis was performed using four different implant neck designs: even surfaced, screwed, three-ring design and four-ring design. Interface are of bone growth was evaluated by analyzing the Bone-Implant-Contact (BIC) parameter obtained from in vivo histological process and analyzed by Scanning Electron Microscopy (SEM). Bone Level implants were inserted in the rabbit tibia, placing two implants per tibia. The BIC was evaluated after three and six weeks of implantation. FEM studies showed that the three-ring design presented lower values of stress distribution compared to the other studied designs. The lower levels of mechanical stress were then correlated with the in vivo studies, showing that the three-ring design presented the highest BIC value after 3 and 6 weeks of implantation. In silico and in vivo results both concluded that the implants with three-ring neck design presented the best biomechanical and histological behavior in terms of new bone formation, enhanced mechanical stability and optimum osseointegration.


Asunto(s)
Implantes Dentales , Diseño de Prótesis Dental , Ensayo de Materiales/métodos , Animales , Tornillos Óseos , Calibración , Implantación Dental Endoósea/instrumentación , Implantes Dentales/normas , Diseño de Prótesis Dental/métodos , Diseño de Prótesis Dental/normas , Análisis de Elementos Finitos , Mandíbula/cirugía , Oseointegración/fisiología , Conejos , Estrés Mecánico , Tibia/cirugía
5.
J Mater Sci Mater Med ; 29(7): 99, 2018 Jun 26.
Artículo en Inglés | MEDLINE | ID: mdl-29946992

RESUMEN

Several dental implants are commercially available and new prototype design are constantly being fabricated. Nevertheless, it is still unclear what parameters of the design affect most the osseointegration of dental implants. The purpose of this study is to assess the effects of the microscopic and macroscopic design of dental implants in the osseointegration by comparing three macroscopic designs (Straumann tissue level (STD), essential cone (ECD) and prototype design (PD)) and six surface treatments. A total of 96 implants were placed in 12 minipigs. The implant stability quotient (ISQ), was assessed at the time of implantation, as well as at 2, 4 and 8 weeks. Histomorphometric and statistical analyses were conducted at the different sacrifice times, being 2, 4 and 8 weeks, to analyse the bone to implant contact (BIC), the bone area density (BAT) and the density of bone outside the thread region (ROI). The macroscopic design results showed higher ISQ values for the ECD, whereas the histomorphometric analysis showed higher ossoeintegration values for the STD. Regarding the microscopic design, both Sandblasted plus acid etching (hydrochloric/sulphuric acid) in a nitrogen atmosphere (SLActive) and Shot-blasted or bombarded with alumina particles and posterior alkaline immersion and thermal treatment (ContacTi) showed superior results in terms of osseointegration and reduced the osseointegration times from 8 weeks to 4 weeks compared to the other analysed surfaces. In conclusion, each of the macroscopic and microscopic designs need to be taken into account when designing novel dental implants to enhance the osseointegration process.


Asunto(s)
Implantes Dentales , Diseño de Prótesis Dental , Oseointegración , Grabado Ácido Dental , Óxido de Aluminio , Animales , Implantación Dental/métodos , Femenino , Ensayo de Materiales , Propiedades de Superficie , Porcinos , Porcinos Enanos , Titanio
6.
Lupus ; 25(12): 1349-56, 2016 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-27053402

RESUMEN

OBJECTIVE: The objective of this study was to determine dental caries frequency and to analyze salivary and bacterial factors associated with active and inactive systemic lupus erythematous (SLE) patients. Also, a proposal to identify dental caries by a surface, teeth, and the patient was developed. MATERIAL AND METHODS: A cross-sectional, blinded study that included 60 SLE patients divided into two groups of 30 subjects each, according to the Activity Index for Diagnosis of Systemic Lupus Erythematous (SLEDAI). The decayed, missing, and filled teeth (DMFT) index and Integrative Dental Caries Index (IDCI) were used for analyzing dental caries. The saliva variables recorded were: flow, pH, and buffer capacity. The DNA copies of Streptococcus mutans and Streptococcus sobrinus were estimated by real-time PCR. RESULTS: The caries frequency was 85% for SLE subjects (73.3% for inactive systemic lupus erythematous (ISLE) and 100% for active systemic lupus erythematous (ASLE)); DMFT for the SLE group was 12.6 ± 5.7 and the IDCI was (9.8 ± 5.9). The ASLE group showed a salivary flow of 0.65 compared with 0.97 ml/1 min from the ISLE group; all variables mentioned above showed a statistical difference (p < 0.05). The salivary pH was 4.6 (6.06 for ISLE and 3.9 for ASLE). The DNA copies of S. mutans and S. sobrinus were high; all variables mentioned above show a significant statistical difference (p < 0.05) between groups. CONCLUSION: SLE patients had high DMFT and IDCI scores that were associated with a decrease in salivary flow, pH, and buffer capacity. There were high counts of S. sobrinus and S. mutans species, and IDCI is a useful tool to provide more detail about dental caries in epidemiological studies.


Asunto(s)
Caries Dental/metabolismo , Caries Dental/microbiología , Lupus Eritematoso Sistémico/metabolismo , Lupus Eritematoso Sistémico/microbiología , Saliva/metabolismo , Adolescente , Adulto , Anciano , Carga Bacteriana , Estudios Transversales , ADN Bacteriano/análisis , Femenino , Humanos , Masculino , Persona de Mediana Edad , Saliva/microbiología , Infecciones Estreptocócicas/microbiología , Infecciones Estreptocócicas/fisiopatología , Streptococcus mutans/genética , Streptococcus mutans/aislamiento & purificación , Streptococcus sobrinus/genética , Streptococcus sobrinus/aislamiento & purificación , Adulto Joven
7.
J Dent Res ; 93(12): 1203-11, 2014 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-25139364

RESUMEN

Periodontitis is an inflammatory disease that causes loss of the tooth-supporting apparatus, including periodontal ligament, cementum, and alveolar bone. A broad range of treatment options is currently available to restore the structure and function of the periodontal tissues. A regenerative approach, among others, is now considered the most promising paradigm for this purpose, harnessing the unique properties of stem cells. How to make full use of the body's innate regenerative capacity is thus a key issue. While stem cells and bioactive factors are essential components in the regenerative processes, matrices play pivotal roles in recapitulating stem cell functions and potentiating therapeutic actions of bioactive molecules. Moreover, the positions of appropriate bioactive matrices relative to the injury site may stimulate the innate regenerative stem cell populations, removing the need to deliver cells that have been manipulated outside of the body. In this topical review, we update views on advanced designs of biomatrices-including mimicking of the native extracellular matrix, providing mechanical stimulation, activating cell-driven matrices, and delivering bioactive factors in a controllable manner-which are ultimately useful for the regenerative therapy of periodontal tissues.


Asunto(s)
Regeneración Tisular Guiada Periodontal/instrumentación , Ingeniería de Tejidos/instrumentación , Andamios del Tejido , Materiales Biomiméticos/uso terapéutico , Regeneración Tisular Guiada Periodontal/métodos , Humanos , Péptidos y Proteínas de Señalización Intercelular/uso terapéutico , Periodontitis/cirugía , Diseño de Prótesis , Células Madre/fisiología , Ingeniería de Tejidos/métodos
8.
Environ Monit Assess ; 186(9): 5393-400, 2014 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-24816591

RESUMEN

The healthcare sector is an important contributor to mercury (Hg) pollution because of the potential presence of mercury in thermometers, blood pressure cuffs, amalgams, etc. There are also other potential sources of mercury in this sector which are used frequently and in high volumes where the presence of the metal is not obvious and which might be collectively contributing to pollution. For instance, some chemicals used for the clinical diagnosis of illness may contain mercury. The goal of this study was to investigate potential sources of mercury pollution, which originate from clinical laboratory discharges, using an exploratory approach. The focus was on the residue generated during automatic analysis of patients' bodily fluids at a medical center in Hermosillo, Sonora, Mexico. This study shows an overview of what might be happening in the region or the country related to non-obvious sources of mercury in the healthcare sector. The results showed measurable levels of mercury in the residues coming from urine sediment analysis. These amounts do not exceed the maximum allowed by Mexican environmental regulations; nevertheless, the frequency and cumulative volume of residues generated, combined with the potential for persistence and the bioaccumulation of mercury in the environment, warrant attention. The work carried out in this study is being taken as a model for future studies for pollution prevention in the healthcare sector with the goal of measuring mercury emissions to the environment from clinical laboratory wastewater, including identifying sources which--while not obvious--could be important given the frequency and volume of their use in the clinical diagnosis.


Asunto(s)
Monitoreo del Ambiente , Contaminantes Ambientales/análisis , Contaminación Ambiental/estadística & datos numéricos , Laboratorios , Mercurio/análisis , Contaminación Ambiental/análisis , México
9.
Acta Biomater ; 10(1): 520-30, 2014 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-24121192

RESUMEN

Novel microcarriers made of sol-gel-derived bioactive glasses were developed for delivering therapeutic molecules effectively while cultivating stem cells for bone tissue engineering. Silica sols with varying concentration of Ca (0-30 mol.%) were formulated into microspheres ranging from 200 to 300 µm under optimized conditions. A highly mesoporous structure was created, with mesopore sizes of 2.5-6.3 nm and specific surface areas of 420-710 m(2)g(-1), which was highly dependent on the Ca concentration. Therapeutic molecules could be effectively loaded within the mesoporous microcarriers during microsphere formulation. Cytochrome C (cyt C), used as a model protein for the release study, was released in a highly sustainable manner, with an almost zero-order kinetics over a period of months; the amount released was ~2% at 9 days, and 15% at 40 days. A slight increase in the release rate was observed in the microcarrier containing Ca, which was related to the dissolution rate and pore size. The presence of Ca accelerated the formation of hydroxyapatite on the surface of the microcarriers. Cells cultured on the bioactive microcarriers were well adhered and distributed, and proliferated actively, confirming the three-dimensional substrate role of the microcarriers. An in vivo study performed in a rat subcutaneous model demonstrated the satisfactory biocompatibility of the prepared microspheres. As a therapeutic target molecule, basic fibroblast growth factor (bFGF) was incorporated into the microcarriers. A slow release pattern similar to that of cyt C was observed for bFGF. Cells adhered and proliferated to significantly higher levels on the bFGF-loaded microcarriers, demonstrating the effective role of bFGF in cell proliferative potential. It is believed that the developed mesoporous bioactive glass microspheres represent a new class of therapeutic cell delivery carrier, potentially useful in the sustainable delivery of therapeutic molecules such as growth factors, as well as in the support of stem cell proliferation and osteogenesis for bone tissue engineering.


Asunto(s)
Huesos/fisiología , Factor 2 de Crecimiento de Fibroblastos/farmacología , Microesferas , Trasplante de Células Madre , Células Madre/citología , Ingeniería de Tejidos/métodos , Adsorción , Animales , Apatitas/química , Materiales Biocompatibles/farmacología , Huesos/efectos de los fármacos , Línea Celular , Proliferación Celular/efectos de los fármacos , Citocromos c/metabolismo , Humanos , Células Madre Mesenquimatosas/citología , Células Madre Mesenquimatosas/efectos de los fármacos , Células Madre Mesenquimatosas/metabolismo , Ratones , Microscopía Electrónica de Rastreo , Nitrógeno/química , Tamaño de la Partícula , Porosidad , Ratas , Células Madre/efectos de los fármacos
10.
Cell Death Dis ; 4: e691, 2013 Jun 27.
Artículo en Inglés | MEDLINE | ID: mdl-23807220

RESUMEN

In most clinical trials, human mesenchymal stem cells (hMSCs) are expanded in vitro before implantation. The genetic stability of human stem cells is critical for their clinical use. However, the relationship between stem-cell expansion and genetic stability is poorly understood. Here, we demonstrate that within the normal expansion period, hMSC cultures show a high percentage of aneuploid cells that progressively increases until senescence. Despite this accumulation, we show that in a heterogeneous culture the senescence-prone hMSC subpopulation has a lower proliferation potential and a higher incidence of aneuploidy than the non-senescent subpopulation. We further show that senescence is linked to a novel transcriptional signature that includes a set of genes implicated in ploidy control. Overexpression of the telomerase catalytic subunit (human telomerase reverse transcriptase, hTERT) inhibited senescence, markedly reducing the levels of aneuploidy and preventing the dysregulation of ploidy-controlling genes. hMSC-replicative senescence was accompanied by an increase in oxygen consumption rate (OCR) and oxidative stress, but in long-term cultures that overexpress hTERT, these parameters were maintained at basal levels, comparable to unmodified hMSCs at initial passages. We therefore propose that hTERT contributes to genetic stability through its classical telomere maintenance function and also by reducing the levels of oxidative stress, possibly, by controlling mitochondrial physiology. Finally, we propose that aneuploidy is a relevant factor in the induction of senescence and should be assessed in hMSCs before their clinical use.


Asunto(s)
Aneuploidia , Senescencia Celular , Células Madre Mesenquimatosas/fisiología , Estrés Oxidativo , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Proliferación Celular , Células Cultivadas , Quimiocina CXCL12/genética , Quimiocina CXCL12/metabolismo , Gelsolina/genética , Gelsolina/metabolismo , Expresión Génica , Regulación de la Expresión Génica , Inestabilidad Genómica , Humanos , Consumo de Oxígeno , Especies Reactivas de Oxígeno/metabolismo , Telomerasa/metabolismo , Homeostasis del Telómero
11.
J Tissue Eng Regen Med ; 7(5): 353-61, 2013 May.
Artículo en Inglés | MEDLINE | ID: mdl-22328196

RESUMEN

Novel hydroxyapatite (HA)-collagen microcarriers (MCs) with different micro/nanostructures were developed for bone tissue-engineering applications. The MCs were fabricated via calcium phosphate cement (CPC) emulsion in oil. Collagen incorporation in the liquid phase of the CPC resulted in higher MC sphericity. The MCs consisted of a porous network of entangled hydroxyapatite crystals, formed as a result of the CPC setting reaction. The addition of collagen to the MCs, even in an amount as small as 0.8 wt%, resulted in an improved interaction with osteoblast-like Saos-2 cells. The micro/nanostructure and the surface texture of the MCs were further tailored by modifying the initial particle size of the CPC. A synergistic effect between the presence of collagen and the nanosized HA crystals was found, resulting in significantly enhanced alkaline phosphatase activity on the collagen-containing nanosized HA MCs.


Asunto(s)
Huesos/efectos de los fármacos , Colágeno/farmacología , Durapatita/química , Durapatita/farmacología , Microesferas , Nanoestructuras/química , Ingeniería de Tejidos/métodos , Animales , Bovinos , Diferenciación Celular/efectos de los fármacos , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Forma de la Célula/efectos de los fármacos , Humanos , Nanoestructuras/ultraestructura , Tamaño de la Partícula , Factores de Tiempo , Difracción de Rayos X
12.
Anal Bioanal Chem ; 402(7): 2347-57, 2012 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-21792551

RESUMEN

Two rapid methods were evaluated for the simultaneous extraction of seven parabens and two alkylphenols from soil based on matrix solid-phase dispersion (MSPD) and microwave-assisted extraction (MAE). Soil extracts were derivatized with N,O-bis(trimethylsilyl)trifluoroacetamide and analyzed by gas chromatography with mass spectrometry. Extraction and clean-up of samples were carried out by both methods in a single step. A glass sample holder, inside the microwave cell, was used in MAE to allow the simultaneous extraction and clean-up of samples and shorten the MAE procedure. The detection limits achieved by MSPD were lower than those obtained by MAE because the presence of matrix interferences increased with this extraction method. The extraction yields obtained by MSPD and MAE for three different types of soils were compared. Both procedures showed good recoveries and sensitivity for the determination of parabens and alkylphenols in two of the soils assayed, however, only MSPD yielded good recoveries with the other soil. Finally, MSPD was applied to the analysis of soils collected in different sites of Spain. In most of the samples analyzed, methylparaben and butylparaben were detected at levels ranging from 1.21 to 8.04 ng g(-1) dry weight and 0.48 to 1.02 ng g(-1) dry weight, respectively.


Asunto(s)
Disruptores Endocrinos/análisis , Cromatografía de Gases y Espectrometría de Masas/métodos , Parabenos/análisis , Fenoles/análisis , Contaminantes del Suelo/análisis , Microondas
13.
J Mater Sci Mater Med ; 22(4): 887-97, 2011 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-21461916

RESUMEN

Collagen-hydroxyapatite (HA) scaffolds for the non-viral delivery of a plasmid encoding the osteoinductive protein bone morphogenetic protein (BMP)-7 were developed. The collagen-HA was obtained by the combination of calcium phosphate cement in a collagen template. The effect on cell behavior of increasing amounts of HA in the scaffolds was evaluated. Collagen-HA scaffolds containing 13, 23 or 83 wt% HA were prepared. Cell proliferation was reduced in the 83% HA scaffold after 1 day compared to 13 and 23% HA, but by 14 days the number of cells in 83% HA considerably increased. Alkaline phosphatase (ALP) activity was 8 times higher for the 83% HA scaffolds. BMP-7 plasmid was incorporated into the 83% HA scaffold. The transfection was low, although significant levels of BMP7 were expressed, associated with an increase in cell proliferation.


Asunto(s)
Cementos para Huesos/química , Fosfatos de Calcio/química , Colágeno/química , Fosfatasa Alcalina/química , Animales , Proteína Morfogenética Ósea 7/metabolismo , Proliferación Celular , Células Cultivadas , Técnicas de Transferencia de Gen , Cabras , Células Madre Mesenquimatosas/citología , Modelos Químicos , Plásmidos/metabolismo , Porcinos , Difracción de Rayos X
14.
Acta Biomater ; 6(8): 2863-73, 2010 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-20123046

RESUMEN

The key feature of calcium phosphate cements (CPCs) lies in the setting reaction triggered by mixing one or more solid calcium phosphate salts with an aqueous solution. Upon mixture, the reaction takes place through a dissolution-precipitation process which is macroscopically observed by a gradual hardening of the cement paste. The precipitation of hydroxyapatite nanocrystals at body or room temperature, and the fact that those materials can be used as self-setting pastes, have for many years been the most attractive features of CPCs. However, the need to develop materials able to sustain bone tissue ingrowth and be capable of delivering drugs and bioactive molecules, together with the continuous requirement from surgeons to develop more easily handling cements, has pushed the development of new processing routes that can accommodate all these requirements, taking advantage of the possibility of manipulating the self-setting CPC paste. It is the goal of this paper to provide a brief overview of the new processing developments in the area of CPCs and to identify the most significant achievements.


Asunto(s)
Cementos para Huesos/síntesis química , Fosfatos de Calcio/síntesis química , Ensayo de Materiales/métodos , Medicina Regenerativa/métodos , Medicina Regenerativa/tendencias , Andamios del Tejido
15.
Food Sci Technol Int ; 16(1): 19-29, 2010 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-21339118

RESUMEN

In this work a methodology to evaluate the sensory properties of honeys has been developed. The sensory analysis was carried out by means of a quantitative descriptive analysis (QDA) method, based on several reference scales, for the coverage of the designed range for each descriptor. The peculiarity of this sensory analysis is that the reference scales have been constituted by common foodstuffs agreed upon by consensus of the panel. The main sensory attributes evaluated in the analyses were: adhesiveness, viscosity, bitterness, aroma, sweetness, acidity, color and granularity. Both the intensity and persistence of honey aromas have also been estimated, together with the classification of the identified aromatic attributes into different groups. The method was applied to 55 artisanal honeys from Madrid (Spain) with the following results: (i) the developed sensory profile sheet allowed a satisfactory description of Madrid honeys; (ii) correlations between sensory attributes of three broad groups of Madrid honeys were obtained and (iii) aroma persistence, sweetness, bitterness, color and granularity appeared as the main sensorial characteristics of honey with discrimination power between floral and honeydew honeys.


Asunto(s)
Análisis de los Alimentos/métodos , Miel/análisis , Sensación , Adhesividad , Adulto , Anciano , Fenómenos Químicos , Femenino , Humanos , Concentración de Iones de Hidrógeno , Masculino , Persona de Mediana Edad , Pigmentación , Olfato , España , Gusto , Tacto , Viscosidad , Adulto Joven
16.
Acta Biomater ; 5(7): 2752-62, 2009 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-19357005

RESUMEN

One key point in the field of tissue engineering and drug delivery is to provide materials with an adequate porosity. Many events, including nutrient and waste exchange in scaffolds for tissue engineering, as well as the drug-loading capacity and control of the release rate in drug delivery systems, are controlled by the size, shape and distribution of the pores in the material. Calcium phosphate cements (CPCs) possess an intrinsic porosity that is highly suited for these applications, and this porosity can be controlled by modifying some processing parameters. The objective of this work was to characterize and control the intrinsic porosity of alpha-tricalcium phosphate (alpha-TCP) cements, and to investigate its role against adsorption of bovine serum albumin (BSA). Cements with different percentages of open porosity (35-55%) were prepared by modifying the liquid-to-powder ratio. In addition, two different TCP particles were used to yield cements with specific surface areas of approximately 20 and approximately 37m(2)g(-1). Mercury porosimetry analysis on the set cements showed in most cases a bimodal pore size distribution which varied with the processing parameters and affected differently the adsorption and penetration of BSA. The peak occurring at larger pore dimensions controlled the penetration of BSA and was ascribed to the voids generated in between crystal aggregates, while the peak appearing at lower pore sizes was believed to be due to the intercrystallite voids within aggregates. It was found that, at the concentrations studied, the high intrinsic porosity in CPC does not ensure protein penetration unless there is an adequate pore size distribution.


Asunto(s)
Cementos para Huesos/química , Fosfatos de Calcio/química , Portadores de Fármacos/química , Ingeniería de Tejidos/métodos , Absorción , Cristalización/métodos , Ensayo de Materiales , Porosidad
17.
Med Hypotheses ; 68(2): 393-6, 2007.
Artículo en Inglés | MEDLINE | ID: mdl-17011727

RESUMEN

Obesity is a disabling disease which has gained greater attention worldwide and particularly in the United States. It significantly increases the risk for other diseases such as insulin independent diabetes mellitus also known as diabetes type 2. The most common surgical procedure for obesity is liposuction. It is traditionally performed either as small-volume liposuction or large-volume liposuction, the majority being small-volume liposuction procedures. Large-volume and small-volume liposuction have been clinically shown to improve insulin sensitivity in obese patients thus reducing their risk of developing type 2 diabetes. In this paper, evidence is presented to support the hypothesis that liposuction disrupts the pathway that brings about insulin insensitivity in the obese patient. It is proposed that using liposuction in the overall treatment of obesity could lead to an improvement in insulin sensitivity and thus greatly improve the quality of life of the obese patient.


Asunto(s)
Diabetes Mellitus Tipo 2/etiología , Lipectomía/efectos adversos , Obesidad/cirugía , Tejido Adiposo/fisiología , Humanos , Factores de Riesgo
18.
Rev. biol. trop ; 53(supl.3): 263-273, dic. 2005. tab, graf
Artículo en Inglés | LILACS | ID: lil-454825

RESUMEN

Mexican Pacific sea urchin studies have been focused mainly on species distribution, ecology and fisheries. Reef degradation by sea urchin bioerosion has not been studied previously en these reefs. We investigate the importance of Diadema mexicanum as a bioerosive agent of coral carbonate at Bahias de Huatulco, and the relative magnitude of coral accretion and bioerosion. At each of five localities in Bahias de Huatulco, sea urchin density, feeding and mechanical (spine) erosion was determined for three size class intervals. In general, D. mexicanum do not exert any significant role on coral reef community structure (live coral, dead coral or algal coverage) at the Huatulco area, probably because they are generally small (2.9-4 cm test size) and few in number (1.0-6.8 ind.m-2). Mean bioerosion rates are consistent with those measured for other diadematoids, as well as other urchin species in various eastern Pacific localities. However, the degree of bioerosive impact depends on species, test size, and population density of urchins. Coral carbonate removal by D. mexicanum erosion varies from 0.17 to 3.28 kgCaCO3m(-2)yr(-1). This represents a carbonate loss of < 5% of the annual coral carbonate production at Jicaral Chachacual, San Agustín and Isla Cacaluta, but 16 and 27% at Isla Montosa and La Entrega. On balance, coral accretion exceeds sea urchin erosion at all sites examined at Huatulco. At Bahias de Huatulco coral reef communities are actively growing, though in the coming years, it might be necessary to investigate the local effects of the interaction among erosion, and environmental and human induced perturbations


Asunto(s)
Animales , Antozoos/fisiología , Conservación de los Recursos Naturales , Carbonatos/metabolismo , Conducta Predatoria/fisiología , Erizos de Mar/fisiología , Agua de Mar/microbiología , Ecosistema , Monitoreo del Ambiente , Conducta Alimentaria/fisiología , México , Densidad de Población , Dinámica Poblacional
19.
Rev Biol Trop ; 53 Suppl 3: 263-73, 2005 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-17469255

RESUMEN

Mexican Pacific sea urchin studies have been focused mainly on species distribution, ecology and fisheries. Reef degradation by sea urchin bioerosion has not been studied previously en these reefs. We investigate the importance of Diadema mexicanum as a bioerosive agent of coral carbonate at Bahias de Huatulco, and the relative magnitude of coral accretion and bioerosion. At each of five localities in Bahias de Huatulco, sea urchin density, feeding and mechanical (spine) erosion was determined for three size class intervals. In general, D. mexicanum do not exert any significant role on coral reef community structure (live coral, dead coral or algal coverage) at the Huatulco area, probably because they are generally small (2.9-4 cm test size) and few in number (1.0-6.8 ind.m-2). Mean bioerosion rates are consistent with those measured for other diadematoids, as well as other urchin species in various eastern Pacific localities. However, the degree of bioerosive impact depends on species, test size, and population density of urchins. Coral carbonate removal by D. mexicanum erosion varies from 0.17 to 3.28 kgCaCO3m(-2)yr(-1). This represents a carbonate loss of < 5% of the annual coral carbonate production at Jicaral Chachacual, San Agustín and Isla Cacaluta, but 16 and 27% at Isla Montosa and La Entrega. On balance, coral accretion exceeds sea urchin erosion at all sites examined at Huatulco. At Bahias de Huatulco coral reef communities are actively growing, though in the coming years, it might be necessary to investigate the local effects of the interaction among erosion, and environmental and human induced perturbations.


Asunto(s)
Antozoos/fisiología , Carbonatos/metabolismo , Conservación de los Recursos Naturales , Conducta Predatoria/fisiología , Erizos de Mar/fisiología , Agua de Mar/microbiología , Animales , Ecosistema , Monitoreo del Ambiente , Conducta Alimentaria/fisiología , México , Densidad de Población , Dinámica Poblacional
20.
Anal Bioanal Chem ; 379(5-6): 812-7, 2004 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-15004736

RESUMEN

The effect of different types of thermal treatment, designed to increase the product's shelf-life, on the volatile composition of "Campo Real" unfermented table olives, has been studied by headspace solid-phase microextraction (HS-SPME) and GC-MS analysis. Different SPME fibres were evaluated to determine their selectivity for a mixture of the main components of the different spices used in "Campo Real" olive dressing. Of the different fibres investigated, the polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibre was selected for analysis of the olive brines, which contained nine main aroma components. The types of thermal treatment were sterilisation (121 degrees C, 15 min) and four pasteurisation conditions (60 degrees C or 80 degrees C each for 5 or 9 min). Pasteurisation did not lead to significant changes in the amounts of these nine volatile compounds; the 2-butanol signal was reduced by treatment at 80 degrees C. On the other hand, sterilisation of the brine resulted in an decrease in the signals from these compounds and the appearance of a new, high signal for benzaldehyde; the origin of this has not yet been determined. Results suggest that the selected pasteurisation conditions do not significantly modify the typical, and valued, aroma characteristics of "Campo Real".


Asunto(s)
Bencenosulfonatos/química , Olea/química , Temperatura , Fermentación , Cromatografía de Gases y Espectrometría de Masas , Aceite de Oliva , Aceites de Plantas/química , Sensibilidad y Especificidad , Factores de Tiempo , Volatilización
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