Bio-Medical Materials and Engineering - Volume 25, issue 3

Authors: Otsuka, Yuta | Yamamoto, Masahiro | Tanaka, Hideji | Otsuka, Makoto

Article Type: Research Article

Abstract: BACKGROUND: Theophylline anhydrate (TA) in tablet formulation is transformed into monohydrate (TH) at high humidity and the phase transformation affected dissolution behavior. OBJECTIVE: Near-infrared spectroscopic (NIR) method is applied to predict the change of pharmaceutical properties of TA tablets during storage at high humidity. METHODS: The tablet formulation containing TA, lactose, crystalline cellulose and magnesium stearate was compressed at 4.8 kN. Pharmaceutical properties of TA tables were measured by NIR, X-ray diffraction analysis, dissolution test and tablet hardness. RESULTS: TA tablet was almost 100% transformed into TH after 24 hours at RH 96%. The pharmaceutical …properties of TA tablets, such as tablet hardness, 20 min dissolution amount (D20) and increase of tablet weight (TW), changed with the degree of hydration. Calibration models for TW, tablet hardness and D20 to predict the pharmaceutical properties at high-humidity conditions were developed on the basis of the NIR spectra by partial least squares regression analysis. The relationships between predicted and actual measured values for TW, tablet hardness and D20 had straight lines, respectively. CONCLUSIONS: From the results of NIR-chemometrics, it was confirmed that these predicted models had high accuracy to monitor the tablet properties during storage at high humidity. Show more

Keywords: Storage at high humidity, theophylline anhydrate, tablet formulation study, tablet hardness, dissolution test, polymorphic transformation, hygroscopicity, chemometrics

DOI: 10.3233/BME-151278

Citation: Bio-Medical Materials and Engineering, vol. 25, no. 3, pp. 223-236, 2015

Authors: Taghipour-Farshi, Hamed | Frounchi, Javad | Ahmadiasl, Nasser | Shahabi, Parviz | Salekzamani, Yaghoub

Article Type: Research Article

Abstract: BACKGROUND: Cuff electrodes have been widely used chronically in different clinical applications. Advancements have been made in selective stimulation by using multi-contact cuff electrodes. Steering anodic current is a strategy to increase selectivity by reshaping and localizing electric fields. There are two configurations for contacts to be implemented in cuff, monopolar and tripolar. A cuff electrode with tripolar configuration can restrict the activation to a more localized region within a nerve trunk compared to a cuff with monopolar configuration and improve the selectivity. Anode contacts in tripolar configuration can be made in two structures, “ring” and “dot”. OBJECTIVE: …In this study, the stimulation capabilities of these two structures were evaluated. METHODS: The recruitment properties and the selectivity of stimulation were examined by measuring the electric potential produced by stimulation currents. RESULTS: The results of the present study indicated that using dot configuration, the current needed to stimulate fascicles in tripolar topologies would be reduced by 10%. It was also shown that stimulation threshold was increased by moving anode contacts inward the cuff. On the other hand, stimulation threshold was decreased by moving the anode contacts outward the cuff which would decrease selectivity, too. CONCLUSIONS: We conclude that dot configuration is a better choice for stimulation. Also, a cuff inward placement of 10% relative to the cuff length was near optimal. Show more

Keywords: Cuff electrode, selective stimulation, steering anode, monopolar, tripolar

DOI: 10.3233/BME-151281

Citation: Bio-Medical Materials and Engineering, vol. 25, no. 3, pp. 237-248, 2015

Authors: Satake, Kazuhiro | Tsukamoto, Megumi | Mitani, Yuji | Regasini, Luis Octavio | da Silva Bolzani, Vanderlan | Efferth, Thomas | Nakagawa, Hiroshi

Article Type: Research Article

Abstract: Multidrug resistance (MDR) caused by human ABCB1 (P-glycoprotein/MDR1) is one of the major obstacles in chemotherapy. To understand the mechanism of MDR by ABCB1 and circumvent the MDR, in the present study, we established human ABCB1-expressing cells (Flp-In-293/ABCB1 cells) and examined the cytotoxic effects of four guanidine alkaloids from Pterogyne nitens (galegine, nitensidine A, pterogynidine and pterogynine) using Flp-In-293/Mock and Flp-In-293/ABCB1 cells. The activity of ABCB1 in Flp-In-293/ABCB1 cells were confirmed by typical substrates for ABCB1 (taxol and vinblastine) in MTT assay. Flp-In-293/ABCB1 cells were also resistant to the four guanidine alkaloids as well as taxol and vinblastine compared …to Flp-In-293/Mock cells although the four guanidine alkaloids exhibited cytotoxicity against the two Flp-In-293 cells. Furthermore, the four guanidine alkaloids were also found to stimulate the ATPase activity of ABCB1 in ATPase assays. These results suggest that ABCB1 can confer the resistance to the cytotoxic guanidine alkaloids by transporting them. Show more

Keywords: ABCB1, P-glycoprotein, ATP-binding cassette (ABC) transporter, guanidine alkaloids

DOI: 10.3233/BME-151282

Citation: Bio-Medical Materials and Engineering, vol. 25, no. 3, pp. 249-256, 2015

Authors: Okada, Mizue | Okada, Yoshinori

Article Type: Research Article

Abstract: Advanced glycation end products’ (AGEs) engagement of a cell-surface receptor for AGEs (RAGE) has been causally implicated in the pathogenesis of vascular complications in diabetic patients. Methanolic extracts from edible plants (MEEP) are naturally occurring phenolic compounds. The phenolic compounds have been reported to possess potent radical-scavenging properties. We investigated whether MEEP could inhibit high glucose-induced RAGE production through interference with reactive oxygen species generation in endothelial cells (ECs). ECs were incubated with 4.5 g/l of glucose in culture medium treated with 21 MEEP. Determination of RAGE production in the culture supernatants was performed by colorimetric ELISA. DNA damage was determined …by using the 8-hydroxydeoxyguanosine ELISA kit. Because peroxynitrite radicals with stronger toxicity were produced by nitric oxide radical (NO), the NO scavenging activity of MEEP was assessed as nitrite generation. Peroxynitrite radical-dependent oxidation inhibition by MEEP was estimated by the Crow method. The results showed that four extracts reduced RAGE production. The extract from onion peel showed the highest RAGE production inhibition activity, followed by that of onion rhizome, cow pea and burdock. The results showed that RAGE production is correlated with the above-mentioned indicators. This study supports the utilization of four extracts for improved treatment of diabetic complications. Show more

Keywords: RAGE, methanolic extracts, human umbilical vein endothelial cells, free radical scavenging activity, edible plants

DOI: 10.3233/BME-151280

Citation: Bio-Medical Materials and Engineering, vol. 25, no. 3, pp. 257-266, 2015

Authors: Miles, Brad | Walter, William L. | Kolos, Elizabeth | Waters, Tim | Appleyard, Richard | Gillies, R. Mark | Donohoo, Shane | Ruys, Andrew J.

Article Type: Research Article

Abstract: BACKGROUND: The design of femoral component used in total hip arthroplasty is known to influence the incidence of periprosthetic femoral fractures (PFFs) in cementless hip arthroplasty. OBJECTIVE: This study was undertaken to determine if 2 potential changes to an existing ABG II-standard cementless implant – addition of a roughened titanium plasma-sprayed proximal coating (ABG II-plasma) and lack of medial scales (ABG II-NMS) could decrease the risk of PFF in the intraoperative and early postoperative periods. METHODS: Six pairs of human cadaveric femurs were harvested and divided into 2 groups, each receiving either of the altered …implants and ABG II-standard (control). Each implant was tested in a biomechanical setup in a single-legged stance orientation. Surface strains were measured in intact femurs, during implant insertion, cyclic loading of the bone with the implant, and loading to failure. Strains with the ABG II-standard and the altered implants were compared. FINDINGS: ABG II-plasma showed better load-bearing capacity, with an average 42% greater failure load than that of ABG II-standard. The cortical hoop, axial and mean strains ABG II-plasma were less than those of ABG II-standard, demonstrating decreased tensile behaviour and better load transfer to the proximal femur. The final residual hoop strains in ABG II-plasma were closer to those of intact bone as compared to the standard stem. No differences in strains were observed between the standard stem and ABG II-NMS. CONCLUSION: The increased load-bearing capacity and decreased proximal surface strains on femurs implanted with ABG II-plasma stem should reduce the risks of intraoperative and early postoperative PFF. Show more

Keywords: Cementless implant, failure load, periprosthetic femoral fractures, strain, titanium plasma-sprayed coating

DOI: 10.3233/BME-151279

Citation: Bio-Medical Materials and Engineering, vol. 25, no. 3, pp. 267-278, 2015

Authors: Kameyama, Atsushi | Bonroy, Kim | Elsen, Caroline | Lührs, Anne-Katrin | Suyama, Yuji | Peumans, Marleen | Van Meerbeek, Bart | De Munck, Jan

Article Type: Research Article

Abstract: The aim of this study was to investigate bonding effectiveness in direct restorations. A two-step self-etch adhesive and a light-cure resin composite was compared with luting with a conventional dual-cure resin cement and a two-step etch and rinse adhesive. Class-I box-type cavities were prepared. Identical ceramic inlays were designed and fabricated with a computer-aided design/computer-aided manufacturing (CAD/CAM) device. The inlays were seated with Clearfil SE Bond/Clearfil AP-X (Kuraray Medical) or ExciTE F DSC/Variolink II (Ivoclar Vivadent), each by two operators (five teeth per group). The inlays were stored in water for one week at 37°C, whereafter micro-tensile bond strength testing …was conducted. The micro-tensile bond strength of the direct composite was significantly higher than that from conventional luting, and was independent of the operator (P < 0.0001 ). Pre-testing failures were only observed with the conventional method. High-power light-curing of a direct composite may be a viable alternative to luting lithium disilicate glass-ceramic CAD/CAM restorations. Show more

Keywords: Micro-tensile bond strength, ceramic inlay, computer-aided design/computer-aided manufacturing (CAD/CAM), luting cement, self-etch

DOI: 10.3233/BME-151274

Citation: Bio-Medical Materials and Engineering, vol. 25, no. 3, pp. 279-288, 2015

Authors: Paul, N.E. | Lösel, R. | Hemmrich, K. | Goy, D. | Pallua, N. | Klee, D.

Article Type: Research Article

Abstract: Adipose tissue engineering is a promising solution for the reconstruction of soft tissue defects. An insufficient neovascularisation within the scaffolds that leads to necrosis and tissue loss is still a major shortcoming of current tissue engineering attempts. Biomaterials, which release angiogenic factors such as L-arginine, could overcome this challenge by supporting the neovascularisation of the constructs. L-arginine is insoluble in organic solvents and thus cannot be incorporated into commonly used polymers in contrast to its ethyl ester. Here, we compared the effects of arginine and its ethyl ester on endothelial cells and preadipocytes, and generated an arginine ethyl ester-releasing, angiogenic …polymer. We cultivated adipose tissue-derived endothelial cells and preadipocytes in arginine-free medium supplemented with L-arginine or L-arginine ethyl ester and assayed the proliferation rate and the degree of adipogenic differentiation, respectively. Additionally, we prepared arginine ethyl ester-releasing poly(D,L-lactide) foils, and investigated their impact on endothelial cell proliferation. We could demonstrate that arginine ethyl ester like arginine significantly increased the proliferation of endothelial cells and preadipocytes without inhibiting an induced adipogenic conversion of the preadipocytes. Further, we could show that the arginine ethyl ester-releasing polymer significantly increased endothelial cell growth. The present data are helpful guidance for generating angiogenic biomaterials that promote endothelial cell growth, and thereby could support neovascularisation within tissue engineering approaches. Show more

Keywords: Arginine, arginine ethyl ester, endothelial cells, preadipocytes, angiogenesis

DOI: 10.3233/BME-151275

Citation: Bio-Medical Materials and Engineering, vol. 25, no. 3, pp. 289-297, 2015

Authors: Nagayama, Kazuaki | Saito, Shunsuke | Matsumoto, Takeo

Article Type: Research Article

Abstract: Vascular smooth muscle cells (SMCs) undergo a phenotypic change from a contractile to a synthetic state under pathological conditions, such as atherogenesis and restenosis. Although the viscoelastic properties of SMCs are of particular interest because of their role in the development of these vascular diseases, the effects of phenotypic changes on their viscoelastic properties are unclear at this stage. We performed the stress relaxation test at constant strain (ε = 30 % ) for the freshly isolated contractile SMCs (FSMCs) and the cultured synthetic SMCs (CSMCs) maintaining in situ cell shape and cytoskeletal integrity. We also investigated …the effect of extracellular Ca2+ on their viscoelastic behaviors. FSMCs and CSMCs exhibited multiphasic stress relaxation, which consisted of rapid relaxation, occurring on a time scale of several seconds and several 10 seconds, and slow relaxation occurring on a time scale of 1000 seconds. The estimated elastic modulus of CSMCs was less than one-half that of FSMCs, that was associated with a decreased of amount of actin stress fibers (SFs) during the transition from contractile to synthetic phenotypes. FSMCs showed a conservation of tension with extracellular Ca2+ following rapid stress relaxation. In contrast, CSMCs showed a consecutive decrease in tension independent of Ca2+ . This suggests that the decrease in tension in a long time scale may be involved in mechanical remodeling of SFs induced through a Rho-dependent pathway, which is Ca2+ -independent and become predominant in the transition from contractile to synthetic phenotypes. Show more

Keywords: Cell biomechanics, mechanical properties, phenotypic changes, micromanipulation, actomyosin contraction

DOI: 10.3233/BME-151276

Citation: Bio-Medical Materials and Engineering, vol. 25, no. 3, pp. 299-312, 2015

Authors: Hedia, H.S. | Fouda, N.

Article Type: Research Article

Abstract: Design of hip joint implant using functionally graded material (FGM) (advanced composite material) has been used before through few researches. It gives great results regarding the stress distribution along the implant and bone interfaces. However, coating of orthopaedic implants has been widely investigated through many researches. The effect of using advanced composite stem material, which mean by functionally graded stem material, in the total hip replacement coated with the most common coated materials has not been studied yet. Therefore, this study investigates the effect of utilizing these two concepts together; FGM and coating, in designing new stem material. It is …concluded that the optimal FGM cemented stem is consisting from titanium at the upper stem layers graded to collagen at a lower stem layers. This optimal graded stem coated with hydroxyapatite found to reduce stress shielding by 57% compared to homogenous titanium stem coated with hydroxyapatite. However, the optimal functionally graded stem coated with collagen reduced the stress shielding by 51% compared to homogenous titanium stem coated with collagen. Show more

Keywords: Finite element, FGM, hip replacement, coating, stress shielding, interface shear stress

DOI: 10.3233/BME-151277

Citation: Bio-Medical Materials and Engineering, vol. 25, no. 3, pp. 313-326, 2015

Authors: Takasaki, Hiroshi | Lim, Edwin C.W.

Article Type: Research Article

Abstract: BACKGROUND: The direction of loading to disc tissue in response to postural changes has been investigated. However, the reported original method may not adequately represent the disc hydration profile. OBJECTIVE: To investigate the reliability of a modified method to measure the direction of shift of disc hydration in response to side-bending. METHODS: Each lumbar disc of 10 healthy subjects was scanned with T2-weighted magnetic resonance imaging in supine (neutral) position and left side-bending position in lying. A mid-point over the pixel intensity profile line was obtained. The differences in mid-point values between the neutral and …side-bending positions were plotted in each direction on a X –Y coordinates plane and the angle (θ ) of each plotted point from the X -axis was calculated. RESULTS: The Intraclass Correlation Coefficients (ICC) of the mid-point values during left side-bending along the sagittal and coronal directions of the disc ranged between 0.72–0.98 and 0.80–0.96, respectively. It was estimated that calculating θ values twice yielded an ICC of 0.8 at each disc level. CONCLUSIONS: The modified method was reliable in capturing gross disc hydration profiles. The direction of shift in disc hydration in response to side-bending can be identified using averaged values of θ that was calculated twice. Show more

Keywords: Intervertebral disc, magnetic resonance imaging, reliability and validity

DOI: 10.3233/BME-151273

Citation: Bio-Medical Materials and Engineering, vol. 25, no. 3, pp. 327-334, 2015