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      • KCI등재

        In Vitro Blood Flow and Cell-Free Layer in Hyperbolic Microchannels: Visualizations and Measurements

        Raquel O. Rodrigues,Raquel Lopes,Diana Pinho,Ana I. Pereira,Valdemar Garcia,Stefan Gassmann,Patrícia C. Sousa,Rui Lima 한국바이오칩학회 2016 BioChip Journal Vol.10 No.1

        Red blood cells (RBCs) in microchannels has tendency to undergo axial migration due to the parabolic velocity profile, which results in a high shear stress around wall that forces the RBC to move towards the centre induced by the tank treading motion of the RBC membrane. As a result there is a formation of a cell free layer (CFL) with extremely low concentration of cells. Based on this phenomenon, several works have proposed microfluidic designs to separate the suspending physiological fluid from whole in vitro blood. This study aims to characterize the CFL in hyperbolic-shaped microchannels to separate RBCs from plasma. For this purpose, we have investigated the effect of hyperbolic contractions on the CFL by using not only different Hencky strains but also varying the series of contractions. The results show that the hyperbolic contractions with a Hencky strain of 3 and higher, substantially increase the CFL downstream of the contraction region in contrast with the microchannels with a Hencky strain of 2, where the effect is insignificant. Although, the highest CFL thickness occur at microchannels with a Hencky strain of 3.6 and 4.2 the experiments have also shown that cells blockage are more likely to occur at this kind of microchannels. Hence, the most appropriate hyperbolic-shaped microchannels to separate RBCs from plasma is the one with a Hencky strain of 3. Red blood cells (RBCs) in microchannels has tendency to undergo axial migration due to the parabolic velocity profile, which results in a high shear stress around wall that forces the RBC to move towards the centre induced by the tank treading motion of the RBC membrane. As a result there is a formation of a cell free layer (CFL) with extremely low concentration of cells. Based on this phenomenon, several works have proposed microfluidic designs to separate the suspending physiological fluid from whole in vitro blood. This study aims to characterize the CFL in hyperbolic-shaped microchannels to separate RBCs from plasma. For this purpose, we have investigated the effect of hyperbolic contractions on the CFL by using not only different Hencky strains but also varying the series of contractions. The results show that the hyperbolic contractions with a Hencky strain of 3 and higher, substantially increase the CFL downstream of the contraction region in contrast with the microchannels with a Hencky strain of 2, where the effect is insignificant. Although, the highest CFL thickness occur at microchannels with a Hencky strain of 3.6 and 4.2 the experiments have also shown that cells blockage are more likely to occur at this kind of microchannels.Hence, the most appropriate hyperbolic-shaped microchannels to separate RBCs from plasma is the one with a Hencky strain of 3.

      • KCI등재

        What nutritional factors influence bone mineral density in Crohn’s disease patients?

        Fernanda Gomes Coqueiro,Raquel Rocha,Camilla Almeida Menezes,Mirella Brasil Lopes,Vanessa Rosa Oliveira,Flora Maria Lorenzo Fortes,Genoile Oliveira Santana 대한장연구학회 2018 Intestinal Research Vol.16 No.3

        Background/Aims: Bone mineral density (BMD) is often low in patients with Crohn’s disease (CD). This study aimed to evaluate the association between nutritional factors and BMD in a group of CD patients. Methods: CD patients 18 years of age or older were included. The body mass index (BMI), waist circumference (WC) and dietary intake were evaluated during two 24-hour recalls. Bone densitometry was performed by dual-energy X-ray absorptiometry of the full body to assess body composition and of the lumbar vertebrae and femoral neck to assess BMD. Results: In the 60 patients evaluated, there was no association between BMD and disease activity or between BMD and disease duration. We observed moderate correlations between BMD in at least one of the evaluated sites and BMI, lean mass, WC, and protein, calcium, phosphorus and magnesium dietary intakes (P<0.05). In the linear regression analysis for spinal BMD, only BMI and calcium dietary intake remained associated (P<0.05). In the linear regression analysis for femoral BMD, WC and phosphorus intake continued to be significant in the final model, although they had low explanatory power for BMD (P<0.05). Conclusions: The prevalence of low BMD was high in CD patients. BMI, WC, calcium and phosphorus dietary intake were positively correlated with BMD.

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        Alchornea glandulosa Ethyl Acetate Fraction Exhibits Antiangiogenic Activity: Preliminary Findings from In Vitro Assays Using Human Umbilical Vein Endothelial Cells

        Flávia Cristine Mascia Lopes,Ana Rocha,Ana Pirraco,Luis O. Regasini,Janaina R. Siqueira,Dulce H.S. Silva,Vanderlan S. Bolzani,Iracilda Z. Carlos,Raquel Soares 한국식품영양과학회 2011 Journal of medicinal food Vol.14 No.10

        Alchornea glandulosa has traditionally been used in Brazilian folk medicine for the treatment of immune-inflammatory diseases and as an antiulcer agent to heal gastric ulcer and gastritis. Angiogenesis is a complex multistep process that consists of proliferation, migration, and anastomosis of endothelial cells and has a major role in the development of pathologic conditions, such as inflammatory diseases. To investigate a possible link between the anti-inflammatory activities and antiangiogenic effects of A. glandulosa ethyl acetate fraction (AGF), this study examined which features of the angiogenic process could be disturbed by this fraction. The antiangiogenic activity of AGF was determined in vitro by using human umbilical vein endothelial cells (HUVEC), and cell viability, proliferation, apoptosis, invasion, and capillary-like structures formation were addressed. To elucidate the mechanism of action, nuclear factor κB (NFκB), a transcription factor implicated in these processes, was also evaluated in HUVEC incubated with AGF. A significant decrease in proliferation, a relevant increase in apoptosis, and a strong reduction in invasion capacity (as assessed by bromodeoxyuridine, terminal deoxynucleotidyl transferase–mediated deoxyuridine triphosphate nick-end labeling, and double-chamber assays, respectively) were observed. AGF also led to a drastic reduction in the number of capillary-like structures formed when HUVEC were cultured on growth factor–reduced Matrigel–coated plates. In addition, incubation of HUVEC with AGF resulted in reduced NFκB activity. These findings emphasize the antiangiogenic potential of AGF and support its therapeutic use for disorders that involve excessive angiogenesis, such as chronic inflammation and tumor growth.

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