Bio-Medical Materials and Engineering - Volume 2, issue 4

Article Type: Other

DOI: 10.3233/BME-1992-2406

Citation: Bio-Medical Materials and Engineering, vol. 2, no. 4, pp. I-I, 1992

Authors: Matsumoto, Takeo | Naiki, Takeru | Hayashi, Kozaburo

Article Type: Research Article

Abstract: Flow characteristics near the end-to-end anastomosis of vascular graft were studied in model tubes by flow visualization techniques. Artery and vascular graft were modelled by an elastic tube fabricated from an elastomeric polymer and a rigid plastic tube, respectively. Anastomotic models were made by connecting these two tubes, which had compliance mismatch at their anastomoses. These model tubes were installed into a mock circulatory loop and flow was visualized using hydrogen bubbles and aluminum powder as the tracer. Flow disturbances including flow separation and eddies were observed near the modelled distal anastomosis (graft-to-artery anastomosis). Peak values of the wall shear …rate were high in the proximal anastomotic area (artery-to-graft anastomosis) and low in the distal region. These phenomena were enhanced in the models with increased compliance mismatch. The local abnormal flow observed in the anastomotic zone might cause thrombus formation and subintimal hyperplasia. To improve the patency in small-calibered arterial grafts, it is important to match their compliance to that of natural arteries. Show more

Keywords: arterial prosthesis, compliance mismatch, end-to-end anastomosis, flow visualization, hydrogen bubble method

DOI: 10.3233/BME-1992-2401

Citation: Bio-Medical Materials and Engineering, vol. 2, no. 4, pp. 171-183, 1992

Authors: Nordström, E. G. | Karlsson, K. H.

Article Type: Research Article

Abstract: A potassium-doped synthetic apatite was prepared by soaking hydroxyapatite in potassium carbonate and potassium chloride solutions. The hydroxyapatite was prepared by firing slip cast ceramic bodies in vacuum at 1100°C. The conical ceramic samples and a crushed material of this were soaked in carbonate and chloride solutions for 2, 4, 6, and 8 weeks. Potassium, calcium, and phosphate were determined by direct current plasma emission spectroscopy. The carbonate content was determined by thermogravimetric analysis and chloride titrimetrically. After 2 weeks, one potassium ion substituted one calcium ion when soaked in a carbonate solution. When soaked in the chloride solution substitution …occurred to the same extent. At phosphate sites the substitution of phosphate for carbonate occurred at one sixth of the sites after 2 weeks. Chloride incorporated one half of the OH-sites after 2 weeks. After 4 weeks about one chloride ion was found in the apatite, and after 6 weeks one and a half of the OH-sites were occupied by chloride ions. Show more

Keywords: hydroxyapatite, potassium, doped

DOI: 10.3233/BME-1992-2402

Citation: Bio-Medical Materials and Engineering, vol. 2, no. 4, pp. 185-189, 1992

Authors: Okumura, Motoaki | Ohgushi, Hajime | Takakura, Yoshinori | van Blitterswijk, Clemens A. | Koerten, Hendrik K.

Article Type: Research Article

Abstract: Porous alumina ceramics alone and combined with rat marrow cells were implanted subcutaneously in the back of syngeneic Fischer rats. Fluorochrome-labeling was performed post operatively and the ceramics were harvested 6 and 8 weeks after implantation. Undecalcified sections of the implants were observed under fluorescence microscopy and the de novo bone-ceramic interfacial areas were analyzed by a scanning electron microscope equipped with an electron probe microanalyzer. Alumina ceramics alone did not show any bone formation, while all marrow cell loaded ceramics showed new bone formation 6 and 8 weeks after implantation. Bone formation was first observed in the center of …the pores and proceeded in a centrifugal direction, leading to contact with the ceramic. These results suggest that bone marrow cells have inherent osteogenic capacity and in the pore region of alumina ceramics progression of the osteogenesis causes the dissipation of intervening fibrous tissue between the de novo bone and alumina ceramic surface. Show more

Keywords: alumina ceramics, bone marrow cell, osteogenesis, heterotopic bone formation, fluorochrome study

DOI: 10.3233/BME-1992-2403

Citation: Bio-Medical Materials and Engineering, vol. 2, no. 4, pp. 191-201, 1992

Authors: Brun, J. L. | Bordenave, L. | Lefebvre, F. | Bareille, R. | Barbié, C. | Rouais, F. | Baquey, Ch.

Article Type: Research Article

Abstract: Our study compared mechanical and biological properties of four materials classically used in surgery: polyethylene terephtalate (Mersilene®), polypropylene (Marlex®), polytetrafluoroethylene (Teflon®) and expanded one (Gore-Tex®) and polyaramide (Kevlar®). No deterioration for polytetrafluoroethylene and polypropylene under irradiation was observed when materials were treated by physical means. Mechanical tests showed that all these materials could bear more than 50 N. Such a high tensile strength is never reached in visceral physiology. Results of graft elongation during tensile strength test shows two classes: a first one that includes high elongation grafts (Gore-Tex and Marlex) and a second one that includes low elongation grafts …(Mersilene and Kevlar). As these materials have many potential uses ,in surgery, we have performed cytotoxicity tests. Material extracts were obtained under standardized conditions, and we have looked at a potentially toxic effect of substances eventually leached from the materials towards cells cultured in vitro. None of the material extracts listed above were cytotoxic except for untreated Kevlar. Toxicity disappeared when Kevlar was treated with methanol. As suspected, untreated Kevlar contains toxic additives introduced during the manufacture of this textile. Thus, in spite of good mechanical properties, Kevlar should not be used in pelvic surgery on account of its lower bicompatibility. These results shows that the choice of the grafts by surgeons must be relevant in a given application. Show more

Keywords: biomaterials, irradiation, tensile strength, elongation, cytotoxicity

DOI: 10.3233/BME-1992-2404

Citation: Bio-Medical Materials and Engineering, vol. 2, no. 4, pp. 203-225, 1992

Article Type: Other

Citation: Bio-Medical Materials and Engineering, vol. 2, no. 4, pp. 227-234, 1992