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1.
J Dairy Sci ; 105(12): 9837-9852, 2022 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-36241435

RESUMEN

In dairy cows, supernumerary teats (SNT) are not desired as they are considered a repository for bacteria; thus, SNT are a risk factor for mastitis. Supernumerary teats are a heritable oligo- or polygenic trait. The incidence of SNT in offspring must be reduced by genomic selection. However, in modern dairy farming, farmers often ignore the effects of SNT on cows. The study aimed to elucidate the effects of SNT on dairy cows from the blood transcriptome level and identify genes associated with SNT in Chinese Holstein cows. We selected 6 SNT cows (Yes) and 6 non-SNT cows (No). In the 6 SNT cows, 3 cows had 1 SNT (One) and 3 cows had 2 SNT (Two). They were divided into 3 comparison groups (One vs. No; Two vs. No; and Yes vs. No). RNA was extracted from blood white membrane cells of 12 cows, and RNA sequencing was performed. Differential gene expression analysis based on the negative binomial distribution was used to detect differentially expressed genes in the One versus No and Two versus No comparison groups. Genes that were significantly upregulated or downregulated both in the One versus No and Two versus No groups (shared genes, SG) were obtained for further analysis. We also performed gene set enrichment analysis for all genes expressed in the Yes versus No group, correlation analysis between SG and the hematological parameters, protein-protein interaction network analysis of SG to select hub genes, and alternative splicing analysis for Yes versus No group to explore the functions of differentially spliced genes. We detected 289 SG. Gene set enrichment analysis, gene ontology, and the Kyoto Encyclopedia of Genes and Genomes enrichment analysis results showed that SNT affect immunity, inflammation, and lactation-related pathways in dairy cows. Correlation analysis showed that LOC104968484, SLC25A6, GADD45G, BAX, APAF1, ATM, XIAP, MDM4, BDP1, CEP350, MED13, TAOK1, SMG1, and RIF1 are associated with white blood cell count and absolute value of lymphocytes in SNT cows only, so they might be genes associated with SNT in Chinese Holstein cows. We found 2 genes (BAX and MDM4) were also differentially spliced genes. However, the causal relationship between these genes and the SNT phenotype needs to be further studied. This study is the first to reveal the adverse effects of SNT on dairy cows at a transcriptional level, and the genes we found can be used as a reference for further searching for candidate genes for the SNT phenotype.


Asunto(s)
ADN Recombinante , Transcriptoma , Femenino , Bovinos , Animales , Proteína X Asociada a bcl-2/genética , Lactancia/genética , Perfilación de la Expresión Génica/veterinaria , China
2.
Sci Total Environ ; 716: 137132, 2020 May 10.
Artículo en Inglés | MEDLINE | ID: mdl-32045768

RESUMEN

Reservoir bays, which are affected by the reservoir and watershed characteristics, are the initial and most sensitive areas in the evolution process of reservoir water quality. However, the relationship between the watershed characteristics and nitrogen and phosphorus concentrations in reservoir bays is poorly understood. We selected 66 bays from the Danjiangkou Reservoir and sampled twice per year (storage and discharge periods) from 2015 to 2018 to monitor the total nitrogen (TN) and total phosphorus (TP) concentration in the waterbodies of the reservoir bays. Four types of watershed characteristic indices (topographic variables, soil variables, land-use composition, and landscape patterns) around these bays were obtained. We quantified the relationship between the TN and TP concentrations and watershed characteristics in the waterbodies of the reservoir bays using partial least squares regression (PLSR). The results showed that the mean concentrations of TN and TP in the storage period (TN:1.69 mg·L-1, TP:0.088 mg·L-1) were higher than those in the discharge period (TN:1.22 mg·L-1, TP:0.063 mg·L-1). The optimal PLSR models explained 67.9% and 82.5% of the TN concentration variability, and 65.4% and 67.2% of the TP concentration variability during the storage and discharge period, respectively. Based on the variable importance in the projection (VIP) values, soil erodibility had significant effects on the TN and TP concentrations. The key factors affecting the TN concentration were the slope gradient, basin relief, topographic wetness index, forest and agricultural land use, whereas the factors controlling the TP concentration were the landscape shape index, edge density, Shannon's diversity index and grass land use, although the TP concentration was also controlled by the patch density and contagion during the storage period, and by mean patch size and largest patch index during the discharge period. This study provides critical insights into sustainable landscape planning and effective reservoir water quality management.

3.
Genet Mol Res ; 15(3)2016 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-27525850

RESUMEN

The high-affinity K(+) transporter (HKT) family comprises a group of multifunctional cation transporters widely distributed in organisms ranging from Bacteria to Eukarya. In angiosperms, the HKT family consists primarily of nine types, whose evolutionary relationships are not fully understood. The available sequences from 31 plant species were used to perform a comprehensive evolutionary analysis, including an examination of selection pressure and estimating phylogenetic tree and gene duplication events. Our results show that a gene duplication in the HKT1;5/HKT1;4 cluster might have led to the divergence of the HKT1;5 and HKT1;4 subfamilies. Additionally, maximum likelihood analysis revealed that the HKT family has undergone a strong purifying selection. An analysis of the amino acids provided strong statistical evidence for a functional divergence between subfamilies 1 and 2. Our study was the first to provide evidence of this functional divergence between these two subfamilies. Analysis of co-evolution in HKT identified 25 co-evolved groups. These findings expanded our understanding of the evolutionary mechanisms driving functional diversification of HKT proteins.


Asunto(s)
Evolución Molecular , Bombas Iónicas/genética , Magnoliopsida/genética , Proteínas de Plantas/genética , Potasio/metabolismo , Duplicación de Gen , Bombas Iónicas/metabolismo , Magnoliopsida/clasificación , Filogenia , Proteínas de Plantas/metabolismo , Selección Genética
4.
Genet Mol Res ; 15(2)2016 May 23.
Artículo en Inglés | MEDLINE | ID: mdl-27323087

RESUMEN

Verticillium wilt caused by soil borne fungus Verticillium dahliae could significantly reduce cotton yield. The Ve1 homologous gene Gbvdr3 is resistant to Verticillium wilt. In order to understand of the function of the promoter Gbvdr3 in Gossypium barbadense, the promoter region of the receptor-like gene Gbvdr3 was obtained by genome walking, and the cis-element in the promoter was identified using the PLACE software in this study. The sequence analysis showed that the promoter contained elements related to stress resistance and light regulation. The cloned promoter was fused to the GUS reporter gene and transformed into Arabidopsis. GUS expression was specifically detected in roots, flowers, and seeds, suggesting that the expression of Gbvdr3 is tissue-specific. Separation and characterization analysis of the promoter of Gbvdr3 provides a platform for further research and application of this gene. Thorough understanding of the function of the Gbvdr3 promoter is important for better understanding of Gbvdr3 function. These results indicated that the promoter of Gbvdr3 was a tissue-specific promoter.


Asunto(s)
Resistencia a la Enfermedad/genética , Gossypium/genética , Enfermedades de las Plantas/genética , Proteínas de Plantas/genética , Arabidopsis/genética , Arabidopsis/crecimiento & desarrollo , Clonación Molecular , Regulación de la Expresión Génica de las Plantas , Genoma de Planta , Gossypium/crecimiento & desarrollo , Gossypium/virología , Enfermedades de las Plantas/virología , Proteínas de Plantas/biosíntesis , Raíces de Plantas , Plantas Modificadas Genéticamente/genética , Regiones Promotoras Genéticas/genética , Microbiología del Suelo , Textiles , Verticillium/genética , Verticillium/patogenicidad
5.
J Hand Surg Eur Vol ; 41(2): 171-6, 2016 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-26221010

RESUMEN

UNLABELLED: This retrospective study was designed to investigate the prevalence, characteristics and natural history of cold intolerance after the use of the reverse digital artery flap. A total of 123 patients were treated between 2010 and 2013. After excluding patients who were lost to follow-up, 87 patients were studied. The mean follow-up time was 34 months (range 14-61). Cold intolerance occurred in 60% (52) of patients after the reverse digital artery flap procedure. The condition improved in only 15% (8) of the patients. Significant differences were observed in the age and the specific digit involved between the groups with and without cold intolerance. There was a lower incidence in younger patients, and the ring finger group showed a lower incidence than in other fingers. Furthermore, the Cold Intolerance Symptom Severity score was positively correlated with the temperature at which cold intolerance was triggered. LEVEL OF EVIDENCE: IV.


Asunto(s)
Frío , Traumatismos de los Dedos/cirugía , Dedos/irrigación sanguínea , Dedos/cirugía , Trastornos de la Sensación/etiología , Colgajos Quirúrgicos/irrigación sanguínea , Adolescente , Adulto , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Prevalencia , Estudios Retrospectivos , Factores de Riesgo , Trastornos de la Sensación/epidemiología , Índice de Severidad de la Enfermedad
8.
J Hand Surg Eur Vol ; 40(9): 935-43, 2015 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-25862526

RESUMEN

UNLABELLED: This retrospective study was designed to compare functional and cosmetic outcomes of the reverse digital artery island flap and reverse dorsal homodigital island flap in fingertip repair. A total of 23 patients were followed for 24 to 30 months. The reverse digital artery island flap was used in 12 patients, and reverse dorsal homodigital island flap in another 11 patients. Flap sensibility was assessed using the Semmes-Weinstein monofilament test and static 2-point discrimination test. Patient satisfaction, active motion of the finger joints, complications and cold intolerance were evaluated. The static 2-point discrimination and Michigan Hand Outcomes Questionnaire (appearance) of the fingers treated with a reverse digital artery flap were significantly better than those with a reverse dorsal homodigital flap. The static 2-point discrimination of the skin-grafted donor sides after dorsal homodigital flap were poorer than that in the contralateral finger. No significant differences were found between the two flaps for pressure or touch sensibility, active ranges of digital motion, complications and cold intolerance. LEVEL OF EVIDENCE: III.


Asunto(s)
Estética , Traumatismos de los Dedos/cirugía , Satisfacción del Paciente , Colgajos Quirúrgicos , Adulto , Femenino , Estudios de Seguimiento , Humanos , Masculino , Rango del Movimiento Articular , Estudios Retrospectivos , Colgajos Quirúrgicos/irrigación sanguínea
9.
J Reconstr Microsurg ; 31(6): 426-33, 2015 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-25803410

RESUMEN

BACKGROUND: Reverse homodigital dorsoradial (RHD) flap has been developed to repair soft-tissue defects of the thumb. However, few articles have reported this flap with long-term follow-up. This retrospective study was designed to evaluate the RHD flap and investigate factors affecting sensory recovery. METHODS: From February 2010 to February 2011, 19 patients were treated consecutively with RHD flap without neurorrhaphy. At final follow-up, flap sensibility was assessed by Semmes-Weinstein (SW) monofilament, moving two-point discrimination (M-2PD), and static two-point discrimination (S-2PD) tests. Patient satisfaction, active range-of-motion of the joints, patient complications, and cold intolerance severity score questionnaire were sequentially evaluated. The patients were divided into two groups based on the S-2PD results and another two groups based on flap size. RESULTS: The mean SW monofilament sensitivity and M-2PD and S-2PD scores on the flap were 4.01 g and 9.26 mm, and 10.63 mm, respectively. Highly positive correlations existed between the flap size and the M-2PD and S-2PD scores. Moreover, in the respective groups based on S-2PD scores and flap size, no statistical difference was found among age, sex, and follow-up time, but the flap size and S-2PD scores were statistically different. CONCLUSIONS: RHD flap without neurorrhaphy is a recommendable technique for relatively small-sized thumb-defect reconstruction, which can achieve a satisfactory sensory recovery.


Asunto(s)
Colgajos Tisulares Libres , Traumatismos de los Tejidos Blandos/cirugía , Pulgar/inervación , Pulgar/cirugía , Adolescente , Adulto , Articulaciones de los Dedos/fisiopatología , Humanos , Persona de Mediana Edad , Satisfacción del Paciente , Rango del Movimiento Articular , Estudios Retrospectivos
10.
Genet Mol Res ; 13(4): 10607-14, 2014 Dec 18.
Artículo en Inglés | MEDLINE | ID: mdl-25526181

RESUMEN

The aim of this study was to investigate the expression and significance of the imprinted gene PEG10 (paternally expressed gene 10) in preeclampsia placental tissue. Quantitative real-time reverse transcriptase polymerase chain reaction and immunohistochemistry to evaluate mRNA and protein expression and distribution of PEG10 in placental tissues obtained from 22 preeclampsia patients (8 patients with mild preeclampsia, 14 cases of severe preeclampsia). At the same time, 22 cases of normal pregnant women served as controls. PEG10 expression was determined in the placental tissue of the two different groups. In the normal pregnancy group, the average expression level of PEG10 was 0.5832 ± 0.045, while in the preeclampsia group, this level was 0.1943 ± 0.035. Statistical analysis showed that the two groups differed significantly (P < 0.05). The downregulated expression of the imprinted gene PEG10 may be an important reason for the occurrence of preeclampsia.


Asunto(s)
Impresión Genómica , Placenta/metabolismo , Preeclampsia/genética , Proteínas/genética , ARN Mensajero/metabolismo , Adulto , Proteínas Reguladoras de la Apoptosis , Proteínas de Unión al ADN , Femenino , Humanos , Preeclampsia/patología , Embarazo , Proteínas/metabolismo , Proteínas de Unión al ARN , Adulto Joven
11.
Acta Biomater ; 4(4): 1095-103, 2008 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-18346948

RESUMEN

Bioglass-based glass-ceramic foams have been developed recently as highly porous, mechanically competent, bioactive and degradable scaffolds for bone tissue engineering. However, the development of the material so far has been based on a trial-and-error approach, and the existing materials are far from being optimized. In this paper, a mechanism-based model is presented for sintering deformation of Bioglass foams. The porous foams consist of struts which, in turn, consist of Bioglass particles. A corresponding two-scale model is developed based on existing viscous sintering models. Crystallization plays a key role in the sintering deformation of Bioglass foams and is taken into account in the model. Qualitative comparison between the model predictions and experimental observations is presented, showing that the model is able to capture the complicated interplay between crystallization and viscous flow during the sintering process.


Asunto(s)
Cerámica/química , Vidrio/química , Modelos Químicos , Ingeniería de Tejidos , Andamios del Tejido , Cristalización , Temperatura
12.
J Biomed Mater Res A ; 84(4): 1049-60, 2008 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-17685403

RESUMEN

Cell support function as well as cell proliferation on highly porous Bioglass(R)-derived glass-ceramic scaffolds (designed for bone tissue engineering) have been assessed in vitro using osteoblast-like cells (MG 63) cultured for up to 6 days. The biodegradation and mechanical stability of the scaffolds in the cell-culture medium have also been investigated. It was found that the scaffolds had excellent cell supporting ability, with cells effectively infiltrating into and surviving at the center of the scaffolds. A quantitative study using the AlamarBlue assay revealed that the proliferation of cells on the glass-ceramic materials was comparable to that on the noncrystallized Bioglass. While the crystalline phase in the glass-ceramic scaffolds transformed into a biodegradable amorphous calcium phosphate phase during cell culture, the mechanical strength of the scaffolds was maintained when compared with that of scaffolds incubated in simulated body fluid or immersed in cell-free culture medium. It is believed that the attached cells and collagen secreted by cells could fill the micropores and microcracks on the surface of the foam struts, thus contributing to the mechanical stability of the degrading scaffolds. In summary, the developed glass-ceramic scaffolds possess the most essential features of a scaffold for bone tissue engineering: they are capable to support and foster relevant cells, able to provide temporary mechanical function, and biodegradable.


Asunto(s)
Materiales Biocompatibles/química , Cerámica , Ingeniería de Tejidos/métodos , Proliferación Celular , Sistema Libre de Células , Colágeno/química , Fuerza Compresiva , Medios de Cultivo/química , Vidrio , Humanos , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Osteoblastos/metabolismo , Oxazinas/química , Estrés Mecánico , Xantenos/química
13.
J Biomed Mater Res A ; 86(4): 987-95, 2008 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-18067165

RESUMEN

A highly interconnected porous scaffold made from 45S5 Bioglass was fabricated by the polymer replica technique and surface functionalized for protein immobilization. Subsequently rat-tail collagen type I was immobilized on the scaffolds. The protein and ion release rates were determined by UV-vis spectroscopy and ion chromatography, respectively, and the impact on hydroxyapatite (HA) formation on the scaffolds upon immersion in SBF was evaluated. It was discovered that the surface functionalization enhanced the stability of the collagen attachment and stability against the increment of pH in a biological environment, resulting in similar collagen release kinetics in solutions of different pH values. Without the surface modification, collagen release was considerably expedited by the increment of pH in a surrounding solution. It was also found that the collagen immobilization does not effect the formation of carbonated HA on the scaffold surface. The stable collagen attachment to the functionalized scaffold makes this approach potentially suitable for improving cell attachment and thus for enhancing the application potential of the scaffold in tissue engineering.


Asunto(s)
Cerámica/metabolismo , Colágeno/metabolismo , Andamios del Tejido , Animales , Vidrio , Concentración de Iones de Hidrógeno , Cinética , Metales , Microscopía Electrónica de Rastreo , Porosidad , Ratas , Propiedades de Superficie , Factores de Tiempo , Difracción de Rayos X
14.
J Tissue Eng Regen Med ; 1(5): 327-42, 2007.
Artículo en Inglés | MEDLINE | ID: mdl-18038427

RESUMEN

Myocardial tissue engineering, a concept that intends to overcome the obstacles to prolonging patients' life after myocardial infarction, is continuously improving. It comprises a biomaterial based 'vehicle', either a porous scaffold or dense patch, made of either natural or synthetic polymeric materials, to aid transportation of cells into the diseased region in the heart. Many different cell types have been suggested for cell therapy and myocardial tissue engineering. These include both autologous and embryonic stem cells, both having their advantages and disadvantages. Biomaterials suggested for this specific tissue-engineering application need to be biocompatible with the cardiac cells and have particular mechanical properties matching those of native myocardium, so that the delivered donor cells integrate and remain intact in vivo. Although much research is being carried out, many questions still remain unanswered requiring further research efforts. In this review, we discuss the various approaches reported in the field of myocardial tissue engineering, focusing on the achievements of combining biomaterials and cells by various techniques to repair the infarcted region, also providing an insight on clinical trials and possible cell sources in cell therapy. Alternative suggestions to myocardial tissue engineering, in situ engineering and left ventricular devices are also discussed.


Asunto(s)
Miocardio/citología , Miocitos Cardíacos/trasplante , Ingeniería de Tejidos/métodos , Materiales Biocompatibles/uso terapéutico , Células Cultivadas , Ensayos Clínicos como Asunto , Insuficiencia Cardíaca/cirugía , Insuficiencia Cardíaca/terapia , Humanos , Modelos Cardiovasculares , Infarto del Miocardio/cirugía , Infarto del Miocardio/terapia , Polímeros , Prótesis e Implantes , Trasplante de Células Madre , Andamios del Tejido , Disfunción Ventricular Izquierda/terapia
15.
J Mater Sci Mater Med ; 18(12): 2269-73, 2007 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-17562142

RESUMEN

Hydroxycarbonate apatite (HCA) coatings on the surface of bioresorbable materials for bone tissue engineering scaffolds were produced using macroporous poly(DL-lactide) (PDLLA) foams impregnated by calcium carbonate in vaterite crystalline form. Stable and homogeneous vaterite deposition on PDLLA foams was achieved using a slurry dipping technique. In vitro studies in simulated body fluid (SBF) were performed to induce formation of (HCA) on the surface of vaterite/PDLLA composite foams. HCA was detected after immersion of foams in SBF for 7 days. Hence, depositing vaterite on materials followed by immersion in SBF is confirmed to induce HCA coatings on the surface of the material. The HCA coated, bioactive and resorbable PDLLA foams are intended for use as bone tissue engineering scaffolds.


Asunto(s)
Implantes Absorbibles , Apatitas/química , Sustitutos de Huesos/síntesis química , Carbonato de Calcio/química , Carbonatos/química , Materiales Biocompatibles Revestidos/síntesis química , Andamios del Tejido , Sustitutos de Huesos/química , Precipitación Química , Materiales Biocompatibles Revestidos/química , Microscopía Electrónica de Rastreo , Poliésteres/química , Polímeros/química , Porosidad , Ingeniería de Tejidos , Difracción de Rayos X
16.
J Mater Sci Mater Med ; 17(11): 979-87, 2006 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-17122908

RESUMEN

The first and foremost function of a tissue engineering scaffold is its role as a substrate for cell attachment, and their subsequent growth and proliferation. However, cells do not attach directly to the culture substrate; rather they bind to proteins that are adsorbed to the scaffold's surface. Like standard tissue culture plates, tissue engineering scaffolds can be chemically treated to couple proteins without losing the conformational functionality; a process called surface functionalization. In this work, novel highly porous 45S5 Bioglass-based scaffolds have been functionalized applying 3-AminoPropyl-TriethoxySilane (APTS) and glutaraldehyde (GA) without the use of organic solvents. The efficiency and stability of the surface modification was assessed by X-ray photoemission spectroscopy (XPS). The bioactivity of the functionalized scaffolds was investigated using simulated body fluid (SBF) and characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). It was found that the aqueous heat-treatment applied at 80 degrees C for 4 hrs during the surface functionalization procedure accelerated the structural transition of the crystalline Na2Ca2Si3O9 phase, present in the original scaffold structure as a result of the sintering process used for fabrication, to an amorphous phase during SBF immersion. The surface functionalized scaffolds exhibited an accelerated crystalline hydroxyapatite layer formation upon immersion in SBF caused by ion leaching and the increased surface roughness induced during the heat treatment step. The possible mechanisms behind this phenomenon are discussed.


Asunto(s)
Materiales Biocompatibles , Cerámica , Vidrio , Ensayo de Materiales , Materiales Biocompatibles/química , Cerámica/química , Vidrio/química , Microscopía Electrónica de Rastreo , Espectrometría por Rayos X , Difracción de Rayos X
17.
Biomaterials ; 27(18): 3413-31, 2006 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-16504284

RESUMEN

Biodegradable polymers and bioactive ceramics are being combined in a variety of composite materials for tissue engineering scaffolds. Materials and fabrication routes for three-dimensional (3D) scaffolds with interconnected high porosities suitable for bone tissue engineering are reviewed. Different polymer and ceramic compositions applied and their impact on biodegradability and bioactivity of the scaffolds are discussed, including in vitro and in vivo assessments. The mechanical properties of today's available porous scaffolds are analyzed in detail, revealing insufficient elastic stiffness and compressive strength compared to human bone. Further challenges in scaffold fabrication for tissue engineering such as biomolecules incorporation, surface functionalization and 3D scaffold characterization are discussed, giving possible solution strategies. Stem cell incorporation into scaffolds as a future trend is addressed shortly, highlighting the immense potential for creating next-generation synthetic/living composite biomaterials that feature high adaptiveness to the biological environment.


Asunto(s)
Implantes Absorbibles , Sustitutos de Huesos/química , Cerámica/química , Ingeniería de Tejidos , Sustitutos de Huesos/síntesis química , Porosidad
18.
J Biomed Mater Res A ; 77(3): 445-57, 2006 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-16444684

RESUMEN

A comparative investigation has been carried out on the mechanical properties and bioactivity of Bioglass-based foams, before and after applying a poly(D,L-lactic acid) (PDLLA) coating layer on the foam struts. It was found that the bioactivity of foams upon immersion in simulated body fluid (SBF) was maintained in the PDLLA-coated foams; however, the transformation kinetics in SBF of the crystalline phase (Na(2)Ca(2)Si(3)O(9)) in the foam struts to an amorphous calcium phosphate phase was retarded by PDLLA coating. The compressive and three-point bending strengths of the Bioglass-based foams were slightly improved by the PDLLA-coating, and the work-of-fracture of the foams was considerably enhanced, as indicated by stress-strain curves. Immersion in SBF for 4 weeks led to a large decrease of the mechanical strength of as-sintered foams decreased (from 0.3 to 0.03 MPa), because of the transformation of the crystalline phase to an amorphous calcium phosphate. On the other hand, the mechanical strength was well-maintained in PDLLA-coated foams after immersion in SBF for 8 weeks. This behavior was attributed to the in-situ formation of a nanocomposite PDLLA/calcium phosphate film on the strut surfaces upon immersion in SBF.


Asunto(s)
Sustitutos de Huesos/química , Cerámica/química , Materiales Biocompatibles Revestidos/química , Ácido Láctico/química , Polímeros/química , Vidrio , Poliésteres
19.
J Biomed Mater Res B Appl Biomater ; 76(2): 354-63, 2006 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-16161126

RESUMEN

New coating processes have been investigated for degradable (Vicryl) and nondegradable (Mersilk) sutures with the aim to develop Bioglass coated polymer fibers for wound healing and tissue engineering scaffold applications. First, the aqueous phase of a Bioglass particle slurry was replaced with a poly(D,L-lactic acid) (PDLLA) polymer dissolved in solvent dimethyle carbonate (DMC) to act as third phase. SEM observations indicated that this alteration significantly improved the homogeneity of the coatings. Second, a new coating strategy involving two steps was developed: the sutures were first coated with a Bioglass-PDLLA composite film followed by a second PDLLA coating. This two-step process of coating has addressed the problem of poor adherence of Bioglass particles on suture surfaces. The coated sutures were knotted to determine qualitatively the mechanical integrity of the coatings. The results indicated that adhesion strength of coatings obtained by the two-step method was remarkably enhanced. A comparative assessment of the bioactivity of one-step and two-step produced coatings was carried out in vitro using acellular simulated body fluid (SBF) for up to 28 days. Coatings produced by the two-step process were found to have similar bioactivity as the one-step produced coatings. The novel Bioglass/PDLLA/Vicryl and Bioglass/PDLLA/Mersilk composite sutures are promising bioactive materials for wound healing and tissue engineering applications.


Asunto(s)
Cerámica , Materiales Biocompatibles Revestidos , Ácido Láctico , Polímeros , Suturas , Apatitas/química , Líquidos Corporales/química , Líquidos Corporales/metabolismo , Cerámica/química , Cerámica/metabolismo , Materiales Biocompatibles Revestidos/química , Materiales Biocompatibles Revestidos/metabolismo , Ácido Láctico/química , Ácido Láctico/metabolismo , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Poliésteres , Polímeros/química , Polímeros/metabolismo , Estrés Mecánico , Propiedades de Superficie , Difracción de Rayos X
20.
J Biomed Mater Res A ; 70(3): 428-35, 2004 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-15293316

RESUMEN

The purpose of this study was to investigate the mineralization leading to osseointegration of strontium-containing hydroxyapatite (Sr-HA) bioactive bone cement injected into cancellous bone in vivo. Sr-HA cement was injected into the ilium of rabbits for 1, 3, and 6 months. The bone mineralization area was found to be largest at 3 months, then at 1 month, and smallest at 6 months (p < 0.01) measured with tetracycline labeling. Osseointegration of Sr-HA cement was achieved at 3 months as observed by scanning electron microscopy. A high calcium and phosphorus area was observed at the interface of bone-Sr-HA cement determined by energy-dispersive X-ray analysis. Transmission electron microscopy gave evidence of the mechanism of bone formation. Dissolution of Sr-HA into debris by the bone remodeling process was thought to increase the concentration of calcium and phosphorus at the interface of bone-Sr-HA cement and stimulate bone formation. Crystalline Sr-HA formed an amorphous layer and dissolved into the surrounding solution, then apatite crystallites were precipitated and formed new bone at 3 months. This young bone then becomes mature bone, which bonds tightly to the Sr-HA cement with collagen fibers inserted perpendicularly after 6 months.


Asunto(s)
Cementos para Huesos/química , Calcificación Fisiológica/fisiología , Hidroxiapatitas/química , Estroncio/química , Animales , Materiales Biocompatibles/química , Materiales Biocompatibles/metabolismo , Cementos para Huesos/metabolismo , Hidroxiapatitas/metabolismo , Ilion/fisiología , Ilion/ultraestructura , Ensayo de Materiales , Oseointegración/fisiología , Conejos , Estroncio/metabolismo
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