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PubMed2004

Effect of calcium and phosphorus ion implantation on the corrosion resistance and biocompatibility of titanium.

This paper is concerned with the corrosion resistance and biocompatibility of titanium after surface modification by the ion implantation of calcium or phosphorus or calcium + phosphorus. Calcium and phosphorus ions were implanted in a dose of 10(17) ions/cm(2). The ion beam energy was 25 keV. The microstructure of the implanted layers was examined by TEM. The chemical composition of the surface layers was determined by XPS and SIMS. The corrosion resistance was examined by electrochemical methods in a simulated body fluid (SBF) at a temperature of 37 degrees C. The biocompatibility was evaluated in vitro. As shown by TEM results, the surface layers formed during calcium, phosphorus and calcium + phosphorus implantation were amorphous. The results of the electrochemical examinations (Stern's method) indicate that the calcium, phosphorus and calcium + phosphorus implantation into the surface of titanium increases its corrosion resistance in stationary conditions after short- and long-term exposures in SBF. Potentiodynamic tests show that the calcium-implanted samples undergo pitting corrosion during anodic polarisation. The breakdown potentials measured are high (2.5 to 3 V). The good biocompatibility of all the investigated materials was confirmed under the specific conditions of the applied examination, although, in the case of calcium implanted titanium it was not as good as that of non-implanted titanium.

Calcium↗

PubMed2005

The effect of choice of sterilisation method on the biocompatibility and biodegradability of SIS (small intestinal submucosa).

SIS (small intestinal submucosa) is a 3D extracellular matrix (ECM) material of porcine origin. It has a complex composition predominantly composed of collagen type I. SIS is rapidly absorbed, supports early and abundant new vessel growth, and serves as a template for the reconstructive remodelling of several body tissues. Currently SIS products are sterilised using ethylene oxide, gamma irradiation and e-beam irradiation. It is not known how they affect the materials properties such as structure, mechanical strength and biocompatibility. This study investigated the influence of each sterilisation method on the biocompatibility and biodegradation of SIS using L929 mouse fibroblasts. SIS samples were sterilised by each of the above methods under standard conditions. The samples were subjected to hydrolytic degradation conditions for specific periods of time. All sterilisation methods resulted in an increase in the rate of sample degradation. The study indicated that over time e-beam irradiation caused the greatest % weight loss. Applying sample extracts to L929 mouse fibroblasts assessed the biocompatibility of the degradation products. The % cellular protein and % metabolic activity were then assessed using the BCA assay and MTT assay, respectively. All SIS samples caused an increase in both cellular protein production and metabolic activity. Initially samples sterilised by ETO had the greatest effect but this decreased after 28 days. Unsterile samples were found to have a slower more prolonged influence. It is thought that the components released may include extractable growth factors and further studies are required to confirm this.

Absorbable Implants↗

PubMed2006

[Research on preparation of silk fibroin and its biocompatibility with rat bone marrow mesenchymal stem cells].

The newly developed approach of tissue engineering has been shown to be great potential on the ligament reconstruction, however, the criterion for the scaffolding material was strict. The scaffold material must have enough strength as well as elasticity, at the same time, it should be biocompatible. As a nature protein, silk is a promising tissue engineering scaffold material for its excellent mechanical property. However, because of the contamination of sericin, the chief problem of silk's medical use is degumming. We compared three degumming reagents to choose the one which has least effect on the mechanical property of silk, and then the best degumming condition was confirmed: 0.4%NazCO3, 90 degrees C, 1 h. Rat bone morrw mesenchymal stem cells (rMSCs) were seeded on the fibroin, and scanning electron microscope (SEM) and fluorescence microscope were used to detect the biocompatibility of it. And the results showed that fibroin had outstanding biocompatibility and cell affinity, which indicated the further use of fibroin in tissue engineering.

Animals↗

PubMed2006

[The effect of the degree of deacetylation of chitosan on the biocompatibility of chitosan membrane with corneal stromal cells].

Some different membranes were prepared by Chitosan with the degree of deacetylation (DD) of 63.7%, 73.7%, 83% and 97% respectively. To study the biocompatibility of Chitosan membrane toward corneal stromal cells, the rabbit cells were cultured on the surface of different DD chitosan membranes. The morphological characteristics, the cell-adhesion, the cell proliferation and the activity of LDH in the medium were investigated. The results of experiment shows that the DD of Chitosan has very significant effect on the biocompatibility of Chitosan membrane toward corneal stromal cells. The more DD of Chitosan, the less injury was made to corneal stromal cells by the chitosan membrane, which is favor of the growing and adhesion of corneal stromal cells. The biocompatibility of the membrane made with low DD Chitosan with corneal stromal cells became worse.

Acetylation↗

PubMed1991

Biocompatibility of urinary catheters--present status.

Biocompatibility aspects of urinary catheters have been recognized by clinicians during the 1980's. After multiple reports of severe urethral damage caused by latex catheters, a series of investigations revealed that toxic substances added to the catheters during the manufacturing process can leak from the devices in situ and cause urethritis developing severe urethral strictures. Consequently, most manufacturers have improved their catheters, but there are still some catheters of inferior quality on the market. Quality is dependent on the biocompatibility testing methods. Cell culture tests are recommended, but there are no common standards regarding these. British Standards Institution has been the first in Europe to adopt toxicity limits for a cell culture test, but those are not acceptable. It is a task for the standardization committees working for the European Community to create adequate biocompatibility testing standards with clinically relevant toxicity limits. If this is not done, the use of latex catheters should be abandoned as potentially harmful devices.

Animals↗

PubMed1991

[Biocompatibility of dental materials. Choice of testing methods: to do or not].

Three methods used to study the biocompatibility of dental materials are compared in this article. A glass-ionomer cement, Vitrabond, was studied, using gutta-percha as the control material. Specimens were standardized according to an original procedure. Unsterilized Vitrabond implants were used, because UV rays modify the material. Intraperitoneal Vitrabond implants increased the macrophage population in rats after 24 hrs. This was caused by the surgical trauma and indicates that this method is unreliable. The intramuscular placement of Vitrabond provoked well defined lesions after a week. The use of histochemical techniques on frozen muscle demonstrated that the concentration of succinic deshydrogenase and acid phosphatase enzymes were altered when compared to the control lesions. A comparison of enzymatic lesions and an evaluation of the areas of cellular growth inhibition during in vitro experiments using a computer image analyzer leads to quantitative conclusions that Vitrabond is a cytotoxic material. The simultaneous use of histochemical techniques on muscle tissue and cell culture in vitro enhances the validity of methods used to evaluate the biocompatibility of dental materials. These methods may be used to test the toxicity of various materials. Nevertheless, for a more complete evaluation of these materials, the allergenicity and carcinogenicity potential of these products should be evaluated, prior to the final verdict as to their biocompatibility.

Animals↗

PubMed1990

New approaches for biocompatibility testing using cell culture.

We are proposing two modified assays for biocompatibility testing which analyze the effects of cytotoxic substances leached from a biomaterial in cell culture. The biocompatibility of two vascular prostheses made of polytetrafluoroethylene was analyzed using the modified assays. One test, the "fluid medium assay" was modified by using small pieces of graft glued to a screening lid, thereby reducing the possibility of mechanical injury to cultured cells by free fragments of the tested biomaterial. Another test, the "cell inhibition assay" was modified in that the biomaterial to be tested was ground into small pieces while at very low temperature. The measure of cell toxicity used was the effect on DNA replication. Our results suggest that these modified assay methods can be used to evaluate the biocompatibility of biomaterials.

Biocompatible Materials↗

PubMedDate not supplied

Biocompatibility of dialysis membranes is of no importance for objective or subjective symptoms during or after hemodialysis.

The clinical importance of biocompatibility of hemodialysis membranes is a matter of controversy. The authors studied the relationship between biocompatibility and acute symptoms during hemodialysis (HD). Twenty-three patients underwent 12 different bicarbonate HD using Cuprophan, Hemophan, or Polyamide membranes for short (2 hr) and long (4 hr) treatments, with small or large membrane areas. Subjective and objective symptoms were registered during HD and 12 and 36 hours thereafter. Type of membrane, membrane area, or Kt/V were of no importance for the occurrence of subjective or objective symptoms. The patients registered fewer symptoms during 2 hr HD with high blood flow than during 4 hr HD with slow blood flow (p = 0.04). Headache was particularly more frequent during the 4 hr HD. Blood pressure, and to some extent subjective symptoms, were influenced by ultrafiltration volume but not by type of membrane. Biocompatibility is not a determinant of acute side effects of hemodialysis.

Biocompatible Materials↗

PubMed1990

[Combined osteosynthesis using biocompatible polymer fixators in the treatment of tubular bone fractures].

In the paper, apart from the results of clinical application of biocompatible polymeric fixatives, are presented the detailed characteristics of physical and mechanical properties of polymeric rods, indicated prospects for development of the following generations of biocompatible polymeric fixatives, exhibiting not only high strength but therapeutic activity as well due to incorporation of different medicinal substances as components of the polymeric base composition. The authors present detailed description of the combined osteosynthesis methods on a basis of use of biocompatible polymeric fixatives according to the fracture localization, period of time elapsed since the moment of trauma etc., analyze the remote results of the treatment.

Biocompatible Materials↗

PubMed1989

[Biocompatibility in long-term hemodialysis: facts--theories--clinical significance].

Biocompatible hemodialysis membranes do not cause major untoward effects due to blood-interface reactions. In principle, however, every component of the extracorporeal circuit may have detrimental effects. Biocompatibility parameters include for example complement components, leukocyte drop, elastase release and interleukin-1 generation. Furthermore, ethylene oxide sensitization, beta 2-microglobulin clearance and endotoxin contamination are of importance. The clinical relevance of biocompatibility in modern hemodialysis is critically discussed.

Biocompatible Materials↗

PubMed1985

Blood lines should be considered in studies of biocompatibility during acetate haemodialysis.

In this one-year prospective study, the biocompatibility of blood lines used for acetate haemodialysis treatment was evaluated in 12 patients. These blood lines, polyvinyl chloride (PVC) and polyurethane extruded PVC (PE) respectively were compared in a schedule of four alternating three-month periods of treatment: PVC/PE/PVC/PE. White blood cell count, complement, IgE and thromboxane values were recorded monthly. A reduction in white blood cell and polymorphonuclear counts after 30 minutes of dialysis was significantly less during period 2 than period 1. Pre-dialysis eosinophil counts varied in a seasonally dependent pattern. We conclude that in spite of their small area, blood lines have some effect on biocompatibility and that the season of the year has to be considered in biocompatibility studies involving eosinophils.

Acetates↗

PubMedDate not supplied

Biocompatibility and performance of a modified cellulosic and a synthetic high flux dialyzer. A randomized crossover comparison between cellulose triacetate and polysulphon.

The biocompatibility and performance of two high flux membranes (modified cellulosic: cellulose-triacetate (CTA), and a synthetic material: polysulphon [PS]) were assessed in 31 stable patients on hemodialysis (HD) in a randomized crossover study. Parameters evaluated included leukocytes, complement activation products C3a and C5a, cytokines, lymphocyte subpopulations, urea, creatinine, phosphate, and beta 2 microglobulin. Considering biocompatibility, the drop in the number of leukocytes was more pronounced during CTA HD compared with PS (p = 0.045), although both were low in comparison with cuprammonium dialysis in the same patients, as observed during a separate study. Both membranes induced a low and transient state of complement activation. Interleukin 1 beta and interleukin 6 could not be detected at all, whereas tumor necrosis factor alpha levels were marginally elevated before and after HD with both membranes. During the first 30 min of HD with either membrane, the numbers of CD8+ cells decreased significantly, resulting in an increase in the CD4/CD8 ratios; in addition, the number of NK cells decreased. Performance, as measured by extraction ratios for small molecular weight solutes and Kt/V urea, was significantly better during CTA dialysis (p < 0.001), but almost similar after correction for membrane surface area. On the basis of these data, it seems justified to conclude that, whereas biocompatibility of the PS dialyzer appeared slightly superior to CTA, performance of both dialyzers was comparable.

Adult↗

PubMed1976

Biomaterials and biocompatibility.

This review attempts to assess the present status of biomaterials, especially in relation to their interaction with tissue. The terms biomaterial and biocompatibility are defined and both the present areas of clinical application and the requirements of biomaterials for these applications discussed. The types of biomaterials in clinical use and those under development are briefly described. Problems associated with implant functionality are covered, dealing with fatigue, wear and membrane permeability. Of more importance are the problems relating to biocompatibility and metallic corrosion, polymer and ceramic degradation, local tissue changes, systemic effects, infection, implant loosening, blood compatibility and the assessment of biocompatibility.

Alloys↗

PubMed1994

Biocompatibility studies with bicarbonate-based solutions.

During long-term peritoneal dialysis (PD) treatment, the biocompatibility of the dialysis fluid is one of the factors that determine the functional integrity of the peritoneal mesothelium and stroma, and the alertness and functional capacity of the peritoneal host defense system. In vitro studies show that conventional acidic lactate-based PD solutions (LB fluids) are detrimental to some of the more important functions of the peritoneal cell system including mesothelial and white blood cells. The main toxic components of the fluids are the high hydrogen ion content (pH = 5-5.6), high lactate concentration, and osmolality. Some toxic side effects can be omitted using bicarbonate-based fluids (BB fluids), in which lactate has been replaced by bicarbonate and the pH has been normalized (7.2-7.4). The present paper is an overview of the biocompatibility tests and studies performed using bicarbonate-based continuous ambulatory peritoneal dialysis (CAPD) fluids. While the final long-term clinical evaluation of the BB fluids is still missing, biocompatibility tests indicate that these fluids are less toxic to many cell systems than the conventional acidic LB fluids. BB fluids with a high glucose content remain cytotoxic. The BB fluids are well tolerated in animal studies. Some BB fluids increase the ultrafiltration in short-term animal studies when compared with LB fluids. The few animal studies failed to demonstrate a better preservation of the peritoneal membrane integrity by BB fluids. The difference in cell toxicity between LB and BB fluids as measured in vitro also seems detectable during the first 30 min of intraperitoneal dwell in man.

Animals↗

PubMed1993

Biocompatibility in hemapheresis: new materials.

The development of new technologies implying the use of semidialytic synthetic membranes in therapeutic apheresis, lays stress also on the problem of biocompatibility. The first alterations of plasma proteins and of the immune system are observable 15 minutes after the beginning of the apheretic session. This may suggest that the acute clinical reactions observed during apheresis are related to biocompatibility. However, the first chronic side effects, comparable to those observed in hemodialysis, do not occur before 10-20 sessions. It is known, in fact, that even when inactive materials, such as the last generation membrane, are used, plasma exchange affects the immune system and may determine plasma protein alterations (protein film, erythrocytic damage, ADP release, beginning of the coagulation process, complement consumption). The whole system or the type of membrane, the involucre, the potting glue and the lines affect the interactions. The contact of blood with a foreign surface initiates a number of local reaction, with subsequent reactivity of the organism. The activation of the complement system, coagulative system, fibrinolytic system and callicrein-kinin system is therefore responsible for the cell functional modifications. It is necessary to underline the role of the membrane surface used, in that the activation of the complement system, of the gathering of platelets and of the cell activity modification all increase with the increase in surface. Biocompatibility may be affected not only by the membranes, but also by the substitution fluids and by the anticoagulant used.

Biocompatible Materials↗

PubMed1995

Biocompatibility aspects of chronic hemodialysis and their clinical relevance.

Even if the definition of the term biocompatibility is still not clear, many of its manifestations during hemodialysis are now well documented. Some of their pathophysiological and clinical implications are briefly reviewed. It appears that not only the dialyzer membrane but also the extracorporeal circuit as a whole should be considered. Biological and clinical evidences confirm that the present more biocompatible membranes seem associated with better acute and long-term tolerance of hemodialysis when compared to less biocompatible membranes. However, potential side-effects such as backfiltration or drug interactions should not be overlooked.

Biocompatible Materials↗

PubMed1996

On the nature of the biocompatibility and on medical applications of NiTi shape memory and superelastic alloys.

Nitinol based shape memory alloys were introduced to Medicine in the late seventies. They possess a unique combination of properties including shape memory, superelasticity, great workability in the martensitic state, resistance to fatigue and corrosion. Despite these exceptional physical, chemical and mechanical properties the worldwide medical application has been hindered for a long time because of the lack of knowledge on the nature of the biocompatibility of these enriched by nickel alloys. A review of biocompatibility with an emphasis on the most recent studies, combined with the results of X-ray surface investigations, allows us to draw conclusions on the origin of the good biological response observed in vivo. The tendency of Nitinol surfaces to be covered with TiO2 oxides with only a minor amount of nickel under normal conditions is considered to be responsible for these positive results. A certain toxicity, usually observed in in vitro studies, may result from the much higher in vitro Ni concentrations which are probably not possible to achieve in vivo. The essentiality of Ni as a trace element may also contribute to the Nitinol biocompatibility with the human body tissues. Examples of successful medical applications of Nitinol utilizing shape memory and superelasticity are presented.

Alloys↗

PubMed1996

Biocompatible dialysis membranes and acute renal failure: a study in post-operative acute tubular necrosis in cadaveric renal transplant recipients.

Previous experimental and human data suggests a detrimental effect on the course of acute renal failure related to exposure of blood to artificial dialysis membranes of poor biocompatibility. We performed a 2.5-year prospective randomized trial to compare the clinical course of acute renal failure (post-operative ischemic acute tubular necrosis, ATN) in patients receiving a cadaveric renal transplant requiring supportive hemodialysis in the immediate post-transplant setting. Patients were randomized to either a cuprophane or polymethylmethacrylate (PMMA) conventional hollow fiber dialyzer. All patients received a standard immunosuppressive regimen which included induction therapy with either horse anti-thymocyte gamma globulin (ATGAM) or the murine anti-CD3 monoclonal antibody (OKT3). Of 53 patients randomized, 17 were excluded (2 for intervening biopsy-proven rejection prior to recovery from ATN, 10 for primary graft nonfunction and 5 for other reasons), leaving 36 evaluable cases of uncomplicated ATN, 18 in each group. There was no difference by age, race, gender, cause of ESRD, immunosuppressive regimen, cold or warm ischemia time, use of pre-transplant dialysis, percent oliguria or the incidence of intra-dialytic hypotension between the 2 groups. There was no difference in the mean time to recovery from ATN posttransplant (8.9 days in the cuprophane group vs 9.5 days in the PMMA group, p = NS) or in the average number of hemodialysis treatments required (3.6 in both groups, p = NS). There was also no difference in long term allograft outcome in terms of the nadir serum creatinine, the number of episodes of subsequent acute rejection or in the development of chronic rejection. An intent-to-treat analysis of all 53 originally randomized patients similarly yielded no significant differences. A subsequent, non-randomized study using a membrane of intermediate biocompatibility (Hemophan) also showed no difference in recovery time from ATN. Bioincompatible membranes do not seem to have a significant clinical impact on the course of recovery of this form of acute renal failure. The striking benefits of biocompatibility in the course of ARF seen in other human trials may relate more to the non-renal systemic toxic effects of bioincompatibility.

Adult↗