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At least 631 records · Page 35Linked to original sources
PubMed1991

Improved biocompatibility of extracorporeal circulation by the use of auto-oxygenation instead of artificial oxygenator in perfusion circuit.

The aim of this study was to determine the biocompatibility of an auto-oxygenation technique of cardiopulmonary bypass. Forty patients undergoing coronary bypass surgery were studied in two groups: A (auto-oxygenation, patients' lungs used in cardiopulmonary bypass) and B (conventional technique of cardiopulmonary bypass with bubble oxygenator). The platelet count decreased to -73% of initial value in group B vs only -27% in group A, P less than 0.001. Platelet aggregation to ADP decreased slightly in group A and hardly at all in group B, P less than 0.001. A transpulmonary leukocyte sequestration was greater in group B: 1.46 +/- 0.5 x 10(3)/mm3 vs only 0.34 +/- 0.2 x 10(3)/mm3 in group A, P less than 0.001. The level of C3a increased in group A from 244 +/- 46 ng/ml to 418 +/- 34 ng/ml and in group B from 268 +/- 46 ng/ml to 521 +/- 65 ng/ml, P less than 0.001, but in group A the levels were significantly less, P less than 0.001. The current study clearly confirms the superior biocompatibility of cardiopulmonary bypass with lung over oxygenator.

Biocompatible Materials↗
PubMed1991

[In vitro and in vivo biocompatibility tests of some endodontic cements].

The major goal of endodontic therapy has been achieved by condensing filling materials into the root canal. It is not uncommon to find excess material in the periapical tissue. It therefore becomes obligatory to use filling materials that have acceptable biocompatibility. The purpose of this investigation was to obtain a "toxicity profile" of some root canal materials and to compare our observations to study results found in literature. Gutta-percha and five endodontic filling cements were tested in vivo and in vitro. The in vivo biocompatibility involved the placement of the test material in 10 mm teflon tubes with an outer diameter of 1,3 mm which were then implanted subcutaneously into rats. The implants were left in situ for periods of 30 and 90 days. The hemolysis test was used for in vitro evaluations. The histological examination showed cellular responses of different intensity and extent. In some cases severe infiltration of inflammatory cells and areas with necrostis were observed. As a result, the root canal materials evaluated showed slight, moderate, and severe reactions, therefore, a different pattern in tissue response.

Animals↗
PubMedDate not supplied

[Animal model for the study of the biocompatibility of root filling materials].

The aim of this study was to investigate the influence of different pins usually used for intraoperative root filling on periapical bone healing. In a specially designed animal experiment it was possible to evaluate biocompatibility simultaneously with the influence of varying materials on bone regeneration in standardized defects. Bioincompatible silver, acrylate and gutta percha root filling delay and impede bone regeneration. Biocompatible aluminium oxide ceramic and titanium pins do not have any influences on spontaneous bone regeneration. Reducing the defect, however, they do improve the conditions for complete bony regeneration.

Acrylic Resins↗
PubMed1991

Biocompatibility and capability of haemopurification systems: review and future development.

Past, present, and future developments of haemopurification systems are reviewed with respect to their biocompatibility and functional capability. The history of the polymethylmethacrylate (PMMA) membrane is introduced, along with the modifications aimed at removing beta 2-microglobulin (beta 2-M). A highly permeable PMMA membrane (BK) has the capability to adsorb beta 2-M. We have succeeded in finding material, thought to be beta 2-M, in transmission electron-microscopy of the membrane perfused with plasma from haemodialysis patients. As examples of the future development of haemopurification systems to remove targeted substances more specifically and efficiently, we consider hybridised bioartificial kidney containing proximal renal tubular cells fixed on collagen hollow fibre for degradation of beta 2-M to aminoacids, and an artificial reticuloendothelial system with polymyxin B immobilised fibre for removing endotoxin in blood. Targeting and specific removal with prepared biocompatible materials will open the way to the development of the second generation systems and close collaboration between medicine and industry is essential for realising these goals.

Biocompatible Materials↗
PubMed1991

The keratoprosthesis: improved biocompatibility through design and surface modification.

Due to poor biocompatibility, the success of keratoprostheses has been limited. We compared a newly-designed PMMA intracorneal keratoprosthesis, covalently coated with type-I collagen, with an identical, uncoated keratoprosthesis were retained for 15 months, the uncoated implants had more extensive adjacent corneal melting, greater inflammatory response, and more epithelial downgrowth than their collagen-coated counterparts. Electron microscopy showed that stromal collagen fibers had attached to the surface of the coated implants, but not to that of the uncoated ones. Intracorneal keratoprostheses covalently coated with type-I collagen may offer superior biocompatibility and become significantly incorporated into corneal tissues.

Animals↗
PubMed1991

Biocompatibility of extracorporeal circulation. In vitro comparison of heparin-coated and uncoated oxygenator circuits.

Oxygenator/tubing sets coated with endpoint-attached heparin were compared to uncoated sets in a dynamic model of extracorporeal circulation. Biocompatibility was assessed by evaluations of complement activation and platelet loss. The median concentration of C3 activation products increased gradually from 12 AU/ml at baseline to 65 AU/ml after 120 minutes in the uncoated sets and from 12 AU/ml to 19 AU/ml after 120 minutes in the coated sets (p less than 0.002). The median concentration of the terminal complement complex in the uncoated sets increased gradually from 3.1 AU/ml at baseline to 18.2 AU/ml after 120 minutes. In the coated sets the terminal complement complex reached a peak of 12.0 AU/ml at 15 minutes and returned to baseline values at 60 minutes. Median platelet loss at 120 minutes was 166 x 10(9) in the uncoated and 21 x 10(9) in the coated sets (p less than 0.01). Heparin coating thus improved biocompatibility by reducing both complement activation and platelet loss.

Biocompatible Materials↗
PubMed1991

Absorption, biocompatibility, and fixation properties of polylactic acid in bone tissue: an experimental study in rats.

The absorption, biocompatibility, and fixation properties of self-reinforced (SR) poly-L-lactic acid (PLLA) and poly-DL-lactic acid (PDLLA) were investigated in cancellous bone in 56 rats. Osteotomies of the distal femur were operatively fixed with cylindrical implants made of SR-PLLA and SR-PDLLA/PLLA (40 PDLLA:60 PLLA). The follow-up times were one, three, six, 12, 24, 36, and 48 weeks. Roentgenographic, microradiographic, histologic, histomorphometric, and oxytetracycline-labeling studies were done. Histologically, there was no evidence of inflammation or foreign-body reaction in the bony tissues. Histomorphometric analysis showed that absorption in the SR-PDLLA/PLLA implant was faster than in the SR-PLLA implant. Absorption started peripherally in the implants and continued with subsequent replacement by new bone. At 48 weeks the implant was completely surrounded by a layer of new bone. The SR-PLLA and SR-PDLLA/PLLA implants were visible in all specimens during the 48-week follow-up period. Ninety-five percent of the osteotomies were consolidated. Implants made of SR polylactic acid in rats proved to be biocompatible and slowly absorbable, and they possessed sufficient mechanical properties for fixation of osteotomies.

Absorption↗
PubMed1990

[Biocompatibility of various surgical drainage materials in the cytotoxicity and implantation test].

The biocompatibility of 10 materials used for surgical drainage was evaluated in a cytotoxicity test and in rat subcutaneous tissue implantation test. All rubber materials and silikolatex were found to be cytotoxic. There was no correspondence of the results of the cytotoxicity test with those of the implantation test. Therefore various procedures for biocompatibility-testing should be used.

Animals↗
PubMed1990

[Biocompatibility of dental amalgam].

The purpose of the present review was to present a detailed description of those current scientific results and opinions relative to the biocompatibility of dental amalgam. The first section of the percent review to the pulpar reactions caused by amalgam fillings, especially when no protective base has been used, while the second part concerns itself with the biocompatibility of the dental amalgam per se. Specifically, reference is made to: a) the adverse reactions due to amalgam fillings both on the patient's physiological system and on the dentist's employing the material under consideration. b) those investigation results bearing a relation on the amount of mercury liberated during the amalgam filling procedures, i.e., mixing, condensation, finishing and polishing and/or removal of old amalgam fillings. c) Liberation of mercury, as well as metallic ions in the patients mouth cavity during chewing and/or during the process of intrabuccal galvanization and corrosion, and d) on the amount of mercury traced in the blood and urine of the patient following amalgam fillings. No conclusive evidence on any adverse reactions on the patient's health, attributable to the liberation of mercury from amalgam fillings, could be presented by the scientific investigations under consideration. Moreover, the number of cases reported on toxic reactions due to dental amalgam is negligible compared to the immense number of amalgam fillings performed in practice. It merits mentioning in this connection, however, the fact that the total amount of mercury attained by the patient from any other source, in conjunction with that liberated from amalgam fillings, could by all means contribute to a number of toxic reactions on the patient's health in general. Conclusively, one could state without reservations, that dental amalgam fillings per se are by and large free of toxic reactions on the patient, based on current scientific observations. Mentioning is finally made on several simple but nevertheless imperative precautions for the safety of public health.

Biocompatible Materials↗
PubMedDate not supplied

Clinical effects of a polyethylene glycol grafted cellulose membrane on thrombogenicity and biocompatibility during hemodialysis.

The biocompatibility and thrombogenicity of polyethylene-glycol (PEG)-grafted cellulose hemodialysis (HD) membranes (PEGC) were investigated in cross-over HD of five HD patients with ordinary cellulose (OC). The PEGC significantly suppressed transient leukocyte and thrombocytopenia, and release of C3a, beta-thromboglobulin and platelet factor 4, in corresponding with the quantity of grafted PEG. HD with PEGC resulted in lower granulocyte elastase production, protein and blood cells adsorption on the membrane surface than those with OC. Minimum heparin in HD with PEGC was three times lower than that with OC, with the thrombin-antithrombin III complex elevation lower than that in HD with OC. The results indicate that the grafted PEG effectively suppresses blood and membrane interaction, thus improving biocompatibility and reducing thrombogenicity in clinical HD.

Biocompatible Materials↗
PubMed1987

[Evaluation of the biocompatibility of a new cellulose membrane by studying the complement system and histamine liberation].

This biocompatibility of the new cellulosic membrane hemophane (HE) is compared to that of cuprophane (CU) in ten maintenance hemodialysis (HD) patients dialyzed on the two types of membranes in randomized order, under otherwise similar technical conditions. Total white blood cell (WBC) and differential counts, blood concentrations of C3a, and C3d and histamine are determined at start of dialysis (TO) and 10, 20 and 180 minutes thereafter. HE is distinct from CU in exerting a minor effect on the generation of C3a, a minor drop of leucocytes during the course of dialysis (P less than 0.01) and also by a lesser increase in blood histamine concentration (P less than 0.05). Histamine liberation is observed on CU together with the generation of anaphylotoxin C3 and with a diminution of circulating basopolymorpho-nuclear cells. According to the variations observed for these three parameters (C3a, leucocytosis and blood histamine concentration), HE appears as being more biocompatible than CU.

Aged↗
PubMed1989

[Arthroplasty of the hip joint using biocompatible self-dissolving polymers (an experimental study)].

This study is devoted to experimental investigation of using a polymeric self-dissolving film of N-vinylpyrrolidine and alkylmethacrylate 100 muk to 300 muk in width for arthroplasty of the hip joint. The experiments were carried out on 10 rabbits whose articular cartilage from the acetabulum was removed and the latter was lined with the polymeric film. The animals were excluded from the experiment at different periods (from 2 weeks to 8 months). It was morphologically determined that the use of a biocompatible film leads to the formation of a new cartilage or a cartilaginous regenerate, which at later terms is replaced by fibrillar connective tissue and fibrillar cartilage, while the biocompatible film plays no direct role in the formation of the cartilage and the connective tissue, but contributes to their emergence under the latter as if under protector.

Animals↗
PubMed1988

[Evaluation of the Caridex system and its pulp biocompatibility].

A study of the pulpal biocompatibility of the Caridex system was carried out on human premolars to be extracted bilaterally for orthodontic reasons, in 3 volunteers aged 10 to 13 years. A class V cavity was prepared bilaterally on the 2 premolars to be extracted: one of the cavities was washed with Caridex. The other was used as a control. The extractions were made immediately, 4 and 7 weeks after these operative procedures. Histological examinations showed that the Caridex system was biocompatible for the human dental pulp. A comparative study of carious cavities was conducted using light microscopy, Gram stain and transmission electron microscopy on the quality of the cleaning obtained after conventional cavity preparation and use of the Caridex system. After Caridex treatment, the dentinal surface was free of demineralized zones and no smear layer was present. The occasional presence of bacteria was noticed after conventional use of a bur as well as after Caridex. More limited clinical indications of the Caridex system are proposed.

Adolescent↗
PubMed1988

Influence of dialysate and membrane biocompatibility on hemodynamic stability in hemodialysis.

The contributions of membrane biocompatibility, dialysate temperature and sodium concentration to hemodynamic stability during hemodialysis were studied in 8 patients with a high incidence of hemodialysis-induced symptomatic hypotension. Patients were treated during 8 different periods, randomly ordered in each case, resulting from the combination of the following: the membrane, either Cuprophan or Polyacrylonitrile; the dialysate temperature, 37 or 35 degrees C, and the sodium concentration, 133 or 139 mmol/l. The incidence of symptomatic hypotension was lower at 35 degrees C in the entire study with either membrane and either sodium concentration. It was also lower with a sodium concentration of 139 mmol/l with either temperature and either membrane. There was a lower incidence of symptomatic hypotension when using Polyacrylonitrile, but this difference was not significant. We conclude that changes in physicochemical parameters of dialysate lead to worth-while improvement of symptomatic hypotension in hemodialysis patients, but membrane biocompatibility seems to play a minor role.

Aged↗
PubMed1986

Biocompatibility and clinical performance of a new modified cellulose membrane.

A new modified cellulose dialysis membrane (MC, 1.2 m2) in which less than 5% of cellulosic OH-groups are substituted by tertiary amino groups was tested in a 6-week clinical trial for biocompatibility and clinical performance and compared to both regenerated cellulose (RC, 1.2 m2) and cellulose acetate (CA, 1.0 m2). Ten patients on maintenance hemodialysis took part in the study; all hollow fiber modules were equally well tolerated and no adverse reactions were observed. Using MC/RC/CA, mean clearances after 15 min of hemodialysis (HD) amounted to 162/169/150 ml/min for urea, to 143/143/124 ml/min for creatinine, and to 104/107/84 ml/min for phosphate (QB = 200 ml/min, QD = 500 ml/min, UFR = 0). Mean drop of systolic blood pressure was 6/10/8 mmHg and mean decrease of heart rate averaged 3/3/3 beats per minute, respectively, during the first hour of HD as compared to starting conditions. Residual blood volume in the modules after HD was low and heparin consumption identical for all 3 membranes (34 IU/kg X h). Mean peak C3a generation for MC/RC/CA amounted to 1312/3486/3099 ng/ml, respectively; leucocyte and platelet counts dropped to a minimum of 67/24/47% and 81/86/91%, respectively during the first hour of HD as compared to initial values. Elastase release from PMNL and platelet factor 4 from platelets showed no significant differences between the membranes. In conclusion, the new MC membrane showed a significantly better biocompatibility and equally good clinical performance as compared to RC and CA.

Biocompatible Materials↗
PubMed1986

Research on dialyzers with improved biocompatibility.

Until now cellulosic membranes, especially Cuprophan, are still widely applied in the treatment of uremic patients. The success of this type of membrane for routine hemodialysis is related to a number of very useful properties with respect to performance, handling and biocompatibility. However, during dialysis Cuprophan membranes induce transient leucopenia which is closely connected with incidentally occurring pulmonary disfunction. These phenomena are thought to be complement mediated and Cuprophan has been recognized as an activator of complement. Synthetic membranes, such as PAN and PMMA show less complement activation than their cellulosic counterparts. Nevertheless these synthetic membranes cannot meet the performance quality of Cuprophan for routine dialysis and therefore dialyzers with synthetic membranes need special precaution to prevent excessive ultrafiltration. Consequently, research has been focussed on the development of a new cellulose-based dialyzer in which excellent performance suitable for routine dialysis is combined with improved biocompatibility. Two different approaches have been followed for the realization of this objective: The application of thinner membranes and The application of modified cellulose.

Biocompatible Materials↗
PubMed1983

[Initial observations on the biocompatibility of a polymer used as a skin dressing].

In the development of a dressing for burn wound covers, a material is required which combines good oxygen permeability, high water content and good biocompatibility with reasonable mechanical properties. One of the most important functions of the cover is to protect the burned surfaces from drying out and to constitute the first defence against microbial invasion. In this study composite sheets crosslinked either in presence of glicerol or diacetin, obtained by reinforcing PHEMA with a tricot PET net have been implanted subacute in rabbits, to test their biocompatibility. The same composites crosslinked in presence of diacetin and grafted on a polybutadene film, have been used as a skin graft on rabbits.

Animals↗