RESUMEN
This study investigated the effect of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP)-modified glass ionomer cement (GIC) on shear bond strength (SBS) and remineralisation of artificial "caries-affected" dentine. Human dentine slices were demineralised and allocated to three groups: group 1, conventional GIC; group 2, CPP-ACP-modified GIC; and group 3, resin-modified GIC. The SBS was measured using a universal testing machine (n = 16 per group). Remaining samples (n = 8 per group) were subjected to pH-cycling for 28 days. After pH-cycling, lesion depth and micro-mechanical properties at the sample-bonding interface were investigated using micro-computed tomography (micro-CT) and nano-indentation, respectively. The SBS for groups 1 to 3 were 4.6 ± 1.5 MPa, 4.2 ± 1.1 MPa, and 5.9 ± 1.9 MPa, respectively (p = 0.007; group 1, group 2 < group 3). Lesion depths determined by micro-CT for groups 1 to 3 were 186 ± 8 µm, 149 ± 14 µm, and 178 ± 8 µm, respectively (p < 0.001; group 2 < group 1, group 3). The mean (±SD, standard deviation) nano-hardness values for groups 1 to 3 were 0.85 ± 0.22 GPa, 1.14 ± 0.21 GPa, and 0.81 ± 0.09 GPa, respectively (p = 0.003; group 1, group 3 < group 2). The mean (±SD) elastic moduli for groups 1 to 3 were 1.70 ± 0.33 GPa, 2.35 ± 0.44 GPa, and 1.59 ± 0.13 GPa, respectively (p < 0.001; group 1, group 3 < group 2). The results suggest that the incorporation of CPP-ACP into GIC does not adversely affect the adhesion to artificial caries-affected dentine. Furthermore, CPP-ACP-modified GIC is superior to conventional GIC in promoting dentine remineralisation.
Asunto(s)
Caseínas/química , Dentina , Cementos de Ionómero Vítreo/química , Resistencia al Corte , Caseínas/ultraestructura , Recubrimiento Dental Adhesivo , Módulo de Elasticidad , Dureza , Humanos , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Microtomografía por Rayos XRESUMEN
The adhesion and traction behavior of leukemia cells in their microenvironment is directly linked to their migration, which is a prime issue affecting the release of cancer cells from the bone marrow and hence metastasis. In assessing the effectiveness of phorbol 12-myristate 13-acetate (PMA) treatment, the conventional batch-cell transwell-migration assay may not indicate the intrinsic effect of the treatment on migration, since the treatment may also affect other cellular behavior, such as proliferation or death. In this study, the pN-level adhesion and traction forces between single leukemia cells and their microenvironment were directly measured using optical tweezers and traction-force microscopy. The effects of PMA on K562 and THP1 leukemia cells were studied, and the results showed that PMA treatment significantly increased cell adhesion with extracellular matrix proteins, bone marrow stromal cells, and human fibroblasts. PMA treatment also significantly increased the traction of THP1 cells on bovine serum albumin proteins, although the effect on K562 cells was insignificant. Western blots showed an increased expression of E-cadherin and vimentin proteins after the leukemia cells were treated with PMA. The study suggests that PMA upregulates adhesion and thus suppresses the migration of both K562 and THP1 cells in their microenvironment. The ability of optical tweezers and traction-force microscopy to measure directly pN-level cell-protein or cell-cell contact was also demonstrated.
Asunto(s)
Carcinógenos/farmacología , Adhesión Celular/efectos de los fármacos , Movimiento Celular/efectos de los fármacos , Leucemia/patología , Mecanotransducción Celular/efectos de los fármacos , Nanotecnología/métodos , Acetato de Tetradecanoilforbol/farmacología , Animales , Antígenos CD , Western Blotting , Cadherinas/metabolismo , Bovinos , Humanos , Células K562 , Leucemia/tratamiento farmacológico , Pinzas Ópticas , Albúmina Sérica Bovina/metabolismoRESUMEN
Engineering 3D microstructures with predetermined properties is critical for stem cell niche studies. We have developed a multiphoton femtosecond laser-based 3D printing platform, which generates complex protein microstructures in minutes. Here, we used the platform to test a series of fabrication and reagent parameters in precisely controlling the mechanical properties of protein micropillars. Atomic force microscopy was utilized to measure the reduced elastic modulus of the micropillars, and transmission electron microscopy was used to visualize the porosity of the structures. The reduced elastic modulus of the micropillars associated positively and linearly with the scanning power. On the other hand, the porosity and pore size of the micropillars associated inversely and linearly with the scanning power and reagent concentrations. While keeping the elastic modulus constant, the stiffness of the micropillars was controlled by varying their height. Subsequently, the single cell traction forces of rabbit chondrocytes, human dermal fibroblasts, human mesenchymal stem cells, and bovine nucleus pulposus cells (bNPCs) were successfully measured by culturing the cells on micropillar arrays of different stiffness. Our results showed that the traction forces of all groups showed positive relationship with stiffness, and that the chondrocytes and bNPCs generated the highest and lowest traction forces, respectively.
Asunto(s)
Fenómenos Biomecánicos , Microscopía de Fluorescencia por Excitación Multifotónica , Proteínas/química , Análisis de la Célula Individual , Animales , Bovinos , Línea Celular , Módulo de Elasticidad , Humanos , Microscopía de Fuerza Atómica , Microscopía de Fluorescencia por Excitación Multifotónica/instrumentación , Microscopía de Fluorescencia por Excitación Multifotónica/métodos , ConejosRESUMEN
OBJECTIVE: To prepare a time-resolved fluoroimmunoassay (TRFIA) kit for clinical detection of IgM antibodies to hepatitis B core antigen (HBc). METHODS: Immunocapture method was used to develop the TRFIA kit for detection of the anti-HBc IgM antibodies, and the precision, cross-reactivity and sensitivity of the kit were tested with the clinical serum samples. RESULTS: The intra- and inter-assay coefficients of variation of the TRFIA kit were 4.8%-7.2% and 7.5%-8.6%, respectively, and no cross-reactivity with anti-HBs, anti-HBc-IgG or anti-HBe was found. Comparison of the results of the TRFIA kit and enzyme-linked immunosorbent assay (ELISA) demonstrated greater sensitivity of the kit than ELISA in detecting the anti-HBc IgM antibodies in 584 serum samples. According to the detection results in 300 serum samples from healthy donors, the cutoff value of the TRFIA kit was 4.5 times of the fluorescence value of the negative control. CONCLUSION: This TRFIA kit for detecting anti-HBc IgM antibodies meets the demand for clinical application and can replace the ELISA kits.