Bio-Medical Materials and Engineering - Volume 21, issue 3

Authors: Tsouknidas, Alexander | Maropoulos, Stergios | Savvakis, Savvas | Michailidis, Nikolaos

Article Type: Research Article

Abstract: Recent advances in Computer Aided Design and Manufacturing techniques (CAD/CAM) have facilitated the rapid and precise construction of customized implants used for craniofacial reconstruction. Data of the patients' trauma, acquired through Computer Topographies (CT), provide sufficient information with regard to the defect contour profile, thus allowing a thorough preoperative evaluation whilst ensuring excellent implant precision. During the selection, however, of a suitable implant material for the specific trauma, the mechanical aspects of the implant have to be considered. This investigation aims to assess the mechanical strength, the shock resistance and the critical deflection of cranial implants manufactured with two commonly …used materials, Polymethylmethacrylate (PMMA) and Ti6Al4V. Even though the strength properties of Ti-alloys are far superior to those of PMMA, there are several aspects that may act in advantage of PMMA, e.g., it is known that discontinuities in the elastic modulus of adjoined parts (bone-implant) lead to bone resorption thus loosening the fixation of the implant over time.The implant design and fixation was the same in both cases allowing a direct comparison of the implant behavior for various loads. Finite Element Methods (FEM) assisted procedures were employed, providing a valuable insight to the neurocranial protection granted by these implants. Show more

Keywords: Cranial implant, FEM, mechanical properties, neurocranial protection

DOI: 10.3233/BME-2011-0663

Citation: Bio-Medical Materials and Engineering, vol. 21, no. 3, pp. 139-147, 2011

Authors: Ito, Yukiko | Kimura, Tsuyoshi | Ago, Yusuke | Nam, Kwangwoo | Hiraku, Kaori | Miyazaki, Kozo | Masuzawa, Toru | Kishida, Akio

Article Type: Research Article

Abstract: Extracellular physical features of underlying the adhesive substrate affect cell adhesion to it substrate. In this study, the effects of vibration, a type of artificial physical stimulation, on the adhesion of mouse L929 cells, mouse embryonic fibroblasts (MEFs), HeLa cells and human umbilical vein endothelial cells (HUVECs) are reported. A nano-vibration system was designed to produce nanometer-scale vibration. When L929 cells, HeLa cells, and HUVECs were subjected to vibration at 100 Hz and 1 kHz, they were not affected. On the other hand, in MEFs, the adherent cells were increased and changed their shape remarkably in response to 1 kHz …vibration. To investigate the MEFs' sensitivity to vibration in detail, the cells shape was classified into four types; round, stellate, filopodia-formed and lamellipodia-formed. In serum addition culture, 1 kHz vibration increased the number of filopodia-formed cells but decreased lamellipodia cells. Furthermore, the preliminary cDNA microarray experiments showed that expression of genes which regulate cytoskeleton were changed by vibration stimulation. These results suggest that vibration could affect cell adhesion and the determination cell shape. Show more

Keywords: Vibration, mouse embryonic fibroblasts, adhesion, cell shape

DOI: 10.3233/BME-2011-0664

Citation: Bio-Medical Materials and Engineering, vol. 21, no. 3, pp. 149-158, 2011

Authors: Bohari, Siti P.M. | Hukins, David W.L. | Grover, Liam M.

Article Type: Research Article

Abstract: Alginate hydrogels have been used widely in tissue engineering for cell encapsulation for several reasons: low toxicity, the ability to gel under gentle condition and compatibility with cells. In this study, we determined the effect of different concentrations of alginate on encapsulation of 3T3 fibroblast cells at two different cell seeding densities. Live/dead staining and MTT assay were performed at regular intervals up to 4 weeks. A Hoechst 33258 assay was done to validate the MTT results. There were more dead cells on day 1 for the higher concentrations of alginate while at, the lower concentration of alginate, cell proliferation …and spheroid formation occurred more quickly. Furthermore, at low cell seeding density, cell proliferation was prolonged compared to the intermediate seeding density. In conclusion, by altering both alginate concentration and cell seeding density, proliferation and spheroid formation can be controlled. Show more

Keywords: Alginate, fibroblast cells, proliferation, spheroid formation, viability

DOI: 10.3233/BME-2011-0665

Citation: Bio-Medical Materials and Engineering, vol. 21, no. 3, pp. 159-170, 2011

Authors: Yokobori Jr., A. Toshimitsu | Ichiki, Masataka | Tomono, Yuki | Tanaka, Daisuke | Kanno, Takashi | Sugiura, Ryuji | Ohtomo, Yuji | Ito, Masatoshi | Ohgoshi, Seiichi

Article Type: Research Article

Abstract: This research was conducted to investigate frequency response of blood vessel wall. The principal frequency of blood vessel wall, f1 was found to decrease with progression of atherosclerosis and irregularity of the vibration trajectory of blood vessel wall was found to increase. When an aneurysm appeared, a new vibration wave was found to appear in the high frequency region, f2 . When the aneurysm wall has enough strength, intensity of high frequency wave was found to increase. However, it decreases with decrease in the strength of aneurysm wall. The visco-elastic deterioration of blood vessel wall was found to well …correlate with the changing characteristics of f1 . A two-dimensional representation of f1 and f2 was conducted which tracks the progression of atherosclerosis and aneurysm. It will enable us to diagnose the introduction period of operation of blood vessel wall of atherosclerosis with an aneurysm. Show more

Keywords: Atherosclerosis, aneurysm, frequency response, blood vessel wall, visco-elastic deterioration

DOI: 10.3233/BME-2011-0666

Citation: Bio-Medical Materials and Engineering, vol. 21, no. 3, pp. 171-177, 2011

Authors: Ozeki, K. | Aoki, H. | Masuzawa, T.

Article Type: Research Article

Abstract: Hydroxyapatite (HA) was coated onto a titanium substrate using radio frequency magnetron sputtering. The sputtered film was crystallized using a hydrothermal treatment. The films were observed using X-ray diffractometry, field emission scanning electron microscopy (FE-SEM) and scanning transmission electron microscopy (STEM) equipped with energy dispersive X-ray spectroscopy (EDX). It was observed that the surface of the hydrothermally-treated film was covered with globular particles. The FE-SEM observations indicated that these particles were composed of columnar grains with a grain size of 20–50 nm. In the STEM cross-sectional observation of the HA–Ti interface, HA crystalline phase regions were observed, in part, …in the non-crystalline phase layer of the as-sputtered film. After the hydrothermal treatment, the HA layer crystallized; the HA crystallization proceeded to a distance of 30 nm above the titanium surface. From an EDX line scan analysis, the titanium oxide layer was not observed at the HA–Ti interface of the as-sputtered film; however, in the hydrothermally-treated film, the titanium oxide layer, with a 15 nm thickness, was observed between the mixing layer and the titanium substrate. The formation of titanium oxide at the HA–Ti interface would contribute to the adhesion improvement of the sputtered film following the hydrothermal treatment. Show more

Keywords: Hydroxyapatite, sputtering, FE-SEM, STEM, FIB

DOI: 10.3233/BME-2011-0667

Citation: Bio-Medical Materials and Engineering, vol. 21, no. 3, pp. 179-189, 2011

Authors: Sasmazel, Hilal Turkoglu | Aday, Sezin | Manolache, Sorin | Gumusderelioglu, Menemse

Article Type: Correction

Abstract: Related article: http://iospress.metapress.com/content/uk80372845742282/

DOI: 10.3233/BME-2011-0668

Citation: Bio-Medical Materials and Engineering, vol. 21, no. 3, pp. 191-191, 2011