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Biomedical subjects

L M Bjursten

Publications and source records attributed to L M Bjursten.

At least 37 records · Page 2Linked to original sources
PubMed1992

Clinical, immunological and bacteriological evaluation of adverse reactions to skin-penetrating titanium implants in the head and neck region.

Between 1977 and October 1989, 445 patients have been treated with bone-anchored skin-penetrating titanium implants for anchorage of facial prostheses or bone-conducting hearing aids, at the Ear, Nose and Throat Department at Sahlgren's Hospital in Gothenburg. The majority of patients had no adverse skin reactions, while a few patients were responsible for the majority of the adverse reactions. The aim of our study was to analyse differences between these groups. We started a clinical study on 9 patients with a clinical history of adverse skin reactions around the titanium implants and 9 patients without adverse skin reactions were used as controls. None of the patients had delayed hypersensitivity to titanium. Microbiological analyses showed that when there was clinical irritation, Staphylococcus aureus could be isolated.

Adolescent↗
PubMed1990

Difference in tissue response to nitrogen-ion-implanted titanium and c.p. titanium in the abdominal wall of the rat.

Ion implantation modifies the surface properties of different materials. We have compared the biological properties of titanium implanted with nitrogen with those of pure titanium. Implants were inserted in the abdominal wall of rats. The implants with surrounding tissue were excised after 1 and 6 weeks, and embedded in epoxy resin. The bulk metal was removed electrochemically and the tissue cut for light and electron microscopy. Using this technique the implant surface, formed by a thin oxide layer, remains and appears in sections as a dense line. After 1 week both types of implants were surrounded by a fluid space containing proteins and scattered macrophages but few polymorphonuclear granulocytes. The fluid space was wider around ion-implanted titanium (52 +/- 22 microns) than around pure titanium implants (15 +/- 3 microns). After 6 weeks the fluid space had largely disappeared around both type of implants. Around pure titanium implants macrophages and fibroblasts, quantified in 1-micron-thick sections in the light microscope, were present in about the same concentration in the inner tissue zone (within 25 microns from the implant surface). Around ion-implanted titanium macrophages predominated in the inner zone and multinuclear giant cells were present in almost all sections. Around both type of implants fibroblasts increased and macrophages decreased with increasing distance from the surface. In the electron microscope macrophages close to the surface of pure titanium were of small size and had an ultrastructure indicating a low activity. Macrophages close to ion-implanted titanium were large and had an active appearance as indicated by the presence of large amounts of endoplasmic reticulum and large Golgi areas in the cytoplasm. Our observations indicate that modification of the surface properties of titanium implants by ion implantation changes the biological properties.

Abdominal Muscles↗
PubMed1990

Method for ultrastructural studies of the intact tissue-metal interface.

Samples were prepared for ultrastructural studies of the intact interface between metallic implants and tissue by transmission electron microscopy. The method is based on plastic embedding of implant and tissue and subsequent removal of the bulk metal by electrochemical dissolution (electropolishing), to facilitate preparation of ultrathin sections for transmission electron microscopy. Surface sensitive spectroscopy (Auger electron microscopy and X-ray photoemission spectroscopy) and transmission electron microscopy EDX results show that the method produces samples with an intact interface, containing the implant surface oxide and the adjacent tissue. Examples of application of the method on titanium, zirconium and aluminium implants in soft tissue are given.

Aluminum↗
PubMed1989

Titanium-hydrogen peroxide interaction: model studies of the influence of the inflammatory response on titanium implants.

In vitro studies of titanium and TiO2 as well as other metals were carried out to investigate the role of these metals in the inflammatory response through the Fenton reaction. The TiOOH matrix formed traps the superoxide radical, so that no or very small amounts of free hydroxyl radicals are produced. Ellipsometry and spin trapping with spectrophotometry and electron spin resonance (ESR) were used to study the interaction between Ti and H2O2. Spectrophotometry results indicated that Ti, Zr, Au and Al are low free OH-radical producers. We propose a new model for the titanium-tissue interface where the oxidized titanium surface is covered with a hydrated TiOOH matrix after the inflammatory reaction. This matrix is suggested to possess good ion exchange properties, and extracellular components may interact with the Ti(IV)-H2O2 compound before matrix formation. The TiOOH matrix is formed when the H2O2 coordinated to the Ti(IV)-H2O2 complex is decomposed to water and oxygen. Superoxide (O2-) may be bound therein. The oxide layer initially present may be partly reformed to a TiOOH matrix due to the interaction with hydrogen peroxide.

Biocompatible Materials↗
PubMed1989

Interaction between hydrogen peroxide and titanium: a possible role in the biocompatibility of titanium.

Hydroxyl radicals formed from hydrogen peroxide during an inflammatory response are potent agents for cellular deterioration. The behaviour of implanted material in terms of its ability to sustain or stop free radical formation may be therefore very important. In vitro studies of titanium which is known to be biocompatible and osseointegrates into human bone were carried out. In our model studies, the production of free radicals from H2O2 at Ti and TiO2 surfaces was measured by spin trapping techniques. Our findings suggest that there is no sustained hydroxyl radical production at a titanium (oxide) surface. We propose that this is due to the quenching of the Fenton reaction through both trapping and oxidation of superoxide radicals in a TiOOH adduct.

Biocompatible Materials↗
PubMed1989

Experience with percutaneous titanium implants in the head and neck: a clinical and histological study.

Percutaneous implants have been associated with numerous problems. However, by using skin-penetrating, bone-anchored titanium implants, developed by Professor Brånemark at the Department of Anatomy, University of Göteborg, good long-term results have been observed. These implants have been in clinical use for anchorage of bone-conducting hearing aids and facial prostheses since 1977 and 1979, respectively. The total number of implants is approximately 700. Less than 4% of the observations have shown significant irritation. Biopsies from 33 patients were collected for histological studies. In the irritated skin there was an increased number of inflammatory cells, mainly polymorphonuclear cells, B-cells, and plasma cells but not T-cells. This suggests a response directed against exogenous agents rather than an allergic reaction against the implant per se.

Ear, External↗
PubMed1988

Hollow implants in soft tissues allowing quantitative studies of cells and fluid at the implant interface.

In order to study the early cellular response in the fluid phase found close to implants in soft tissues, an experimental method using a hollow implant was developed. The fluid present in an interior chamber communicating with the exterior of the implant was analysed. Polymorphonuclear granulocytes (PMNGs) were predominant during the study (1-9 days). In titanium implants a slight increase in cell numbers with time was noted, whereas in polytetrafluoroethylene (PTFE) implants, a sharp increase in cell numbers was observed. Preliminary studies showed that sufficient amounts of fluid and cells could be retrieved for analysis of protein composition and inflammatory cell activation.

Animals↗
PubMed1988

Clinical aspects of osseointegration in joint replacement. A histological study of titanium implants.

In an experimental clinical study, 25 implants of pure titanium were inserted into the proximal tibia of 11 volunteer patients, four with rheumatoid arthritis and seven with osteoarthritis. The implants were removed from five weeks to 24 months later and detailed histological analysis was performed. The implants generally healed with direct bone-metal contact, showing so-called osseointegration. Only one of the 21 implants which had been in place for over five months did not show osseointegration, probably because of inadequate primary contact with bone. The presence of rheumatoid disease did not prevent osseointegration, but accompanying osteoporosis seemed to be a risk factor.

Aged↗
PubMed1988

Soft tissue reactions around percutaneous implants: a clinical study of soft tissue conditions around skin-penetrating titanium implants for bone-anchored hearing aids.

Some patients with hearing impairment cannot use conventional hearing aids. One solution for these patients is the use of bone conduction hearing aids; however, this kind of equipment is associated with several problems related to the necessity for a good contact between the transducer and the temporal bone. Direct bone contact would be an ideal solution provided that safe and reaction-free skin penetration and a safe and permanent bone anchorage could be achieved. Brånemark et al have developed a procedure to furnish edentulous patients with fixed bridges using titanium implants. This report is focused on the clinical status of the soft tissue adjacent to the 67 skin-penetrating devices in 60 patients. The patients have been followed between 3 and 96 months on 313 occasions, which represents a total observation time of 1515 months of clinical performance. Only one implant was extracted due to adverse skin reaction, giving a failure rate of 0.07% per month. This is comparable with the failure rate of cardiac pacemakers 0.02-0.04% per month).

Biocompatible Materials↗
PubMed1986

Optimized density gradient separation of leukocyte fractions from whole blood by adjustment of osmolarity.

Some of the compounds used for density gradient separation of blood cells have high osmolarities at the concentrations needed to create the required specific densities. Several mixed media use a combination of hyperosmolar shrinkage and red cell aggregation to improve cell separation. Due to the characteristics of Percoll density gradient medium the density and osmolarity of the gradient can be controlled separately. In the present study, Percoll gradients were used to determine the buoyant densities of different human blood cells at the osmolarities 300 mosM, 350 mosM and 400 mosM. Cell volumes were measured at the same osmolarities using a Coulter counter with channelyzer. As expected, the cell buoyant densities increased and the cell volumes decreased at the higher osmolarities used. There were, however, quantitative differences between the cells with respect to the effects of an increased osmolarity, making a 350 mosM density gradient the most effective in separating mononuclear leukocytes from polymorphonuclear leukocytes. A 400 mosM gradient offered the best possibilities to separate red blood cells from polymorphonuclear leukocytes. A one-step centrifugation procedure, based on these principles, is presented. This procedure makes possible the simultaneous purification of mononuclear leukocytes and polymorphonuclear leukocytes, suitable for functional assays.

Cell Separation↗
PubMed1986

Joint fluid leukocyte activation by preformed immune complexes.

Acute synovitis was induced in rabbit knee joints by intraarticular injection of preformed bovine serum albumin (BSA) -anti BSA immune complexes (ICs). Polymorphonuclear granulocytes (PMNGs) which had migrated into joints injected with ICs were degranulated and contained ICs as revealed by electron microscopy and were activated as revealed by the measurement of chemiluminescence (CL). In contrast, leukocytes from control joints injected with BSA and normal rabbit serum as well as glycogen-elicited peritoneal leukocytes did not display any morphological changes and did not show CL. Compared to cells from other sources, leukocytes from IC joints showed a decreased CL response when stimulated in vitro with ICs but not with opsonized zymosan, suggesting a stimulus-specific modification of the PMNG responsiveness. Inhibition experiments showed that oxygen radicals and formation of arachidonate metabolites, mainly of the lipoxygenase pathway, were involved in the CL response of the IC-stimulated joint fluid PMNGs. Our observations on morphology, activity, and responsiveness of emigrated cells from the various sources suggest, together with previous observations, that the reaction of leukocytes in IC-induced synovitis consists of an initial migration phase not related to an increased CL and a subsequent activation phase characterized by degranulation, phagocytosis of ICs and increased CL.

Animals↗
PubMed1986

Implants in the abdominal wall of the rat.

An experimental model is presented that allows qualitative as well as quantitative studies of the soft tissue response to implant materials used in reconstructive surgery. Plugs of non-alloyed titanium and polymers (Teflon, Delrin) were inserted into the abdominal wall of rats, with a portion of the plug penetrating through the peritoneum into the abdominal cavity. The tissue reaction was evaluated by means of light and electron microscopy for up to 9 weeks after insertion. Titanium implants were in direct contact with the connective tissue without intervening inflammatory cells. The defect in the peritoneum was sealed by a close apposition of the mesothelial membrane to the titanium surface and no connective tissue surrounded the intra-peritoneal portion of the plug. In contrast, a fibrous capsule surrounded the intra-peritoneal portion of Teflon and Delrin implants. A reactive zone consisting of active macrophages and giant cells was present at the surface of these implants separating the implant from the surrounding fibrous capsule. This study shows that the tissue response at the interface to foreign materials can be studied using light and electron microscopic techniques and that profound differences in tissue response exist between different materials.

Abdominal Muscles↗
PubMed1986

Acute synovitis induced by preformed immune complexes.

The morphology of acute immune complex (IC) elicited synovitis in rabbit knee joints was studied, as well as IC-induced leukocyte activation in vivo and in vitro. Acute synovitis was induced by intra-articular injection of in vitro preformed, complement activating bovine serum albumin (BSA)-anti-BSA IC. Within 30 min, migration of polymorphonuclear granulocytes (PMNGs) was observed. Scanning electron microscopy showed that adhering, apparently activated leukocytes were attached to the synovial lining, often forming clusters. Phagocytosis of IC was evident, as immunoglobulins were detected within the leukocyte cytoplasm by the direct immunofluorescence technique. At the peak accumulation of PMNGs, focal erosions of the synovial lining were observed. Later, monocytes and macrophages appeared and degenerated PMNGs were found, sometimes within the cytoplasm of large macrophages. Chemiluminescence experiments showed a maximum in vitro activation of leukocytes by complement activating IC formed near optimal precipitation proportions and in slight antigen excess, whereas IC in large antigen excess gave a smaller and later response.

Acute Disease↗
PubMed1985

Proliferative synovitis in rabbit knee joints induced by antigen and preformed immune complexes.

Knee joints of non-immunized rabbits were repeatedly injected with bovine serum albumin (BSA) and preformed BSA-anti-BSA immune complexes which had differing precipitation profiles and abilities to activate complement. Ten days after the last of six injections the antibody and lymphoproliferative responses to BSA were analysed and correlated to the degree of arthritis. Joint swelling, increased numbers of joint fluid leukocytes and morphological changes typical of proliferative synovitis were found only in those rabbits injected with a large dose of antigen or with immune complexes prepared in antigen excess of poor precipitation and complement-activating properties in vitro. The degree of arthritis correlated with the development of humoral and lymphoproliferative immune responses to BSA.

Animals↗
PubMed1984

Inhibitory effect of honey bee venom on immune complex mediated leukocyte migration into rabbit knee-joints.

The anti-inflammatory effect of purified honey bee venom (HBV) was studied using a recently described animal model in which preformed immune complexes were injected into rabbit knee-joints. As little as a single injection of 1.2 micrograms HBV/kg body weight subcutaneously significantly reduced the immune complex induced joint inflammation as measured by reduction in leukocyte counts in the joint fluid. This decrease was obvious 3 and 6 but not 9 hours after induction of the inflammation. There was no significant effect on leukocyte random migration, chemotactic responsiveness or phagocytosis, indicating that HBV did not interfere with normal phagocyte motility and ingestion. The modifying effects by HBV on the inflammatory response to immune complexes in vivo is most likely due to interference with other components of the inflammatory response.

Animals↗
PubMed1984

Influence of adhesins on the interaction of Escherichia coli with human phagocytes.

The fitness between bacterial adhesins and target cell receptors, determining bacterial adherence to epithelial cells in urinary tract infections, was shown to influence also the interaction with human polymorphonuclear leukocytes (PMNL). Two sets of homogenic strains, constructed to express either, both, or none of the globotetraosylceramide-sensitive (GS) adhesins specific for globoseries glycolipid receptors or the mannose-sensitive (MS) adhesins inhibited by alpha-methyl mannoside were compared regarding charge, hydrophobicity, and binding to PMNL. The mutants of a hydrophilic pyelonephritis strain required MS adhesins for binding to and activation of the PMNL. Removal of the MS adhesins from the mutant carrying both MS and GS adhesins abolished chemiluminescence and binding. A pronounced chemiluminescence reaction was induced by the hydrophobic strain without GS or MS adhesins . Transformants of this strain expressing the MS adhesin bound to and activated the PMNL. Poor binding and activation were found with mutants and transformants carrying only the GS adhesins . The improved reactivity after coating of the PMNL with the appropriate receptor glycolipid supported the previously reported absence of globoseries glycolipids in those cells as the reason for the refractoriness to bacteria with GS adhesins . The mechanism of binding, which improves epithelial cell adhesion, may prevent binding to PMNL, thus improving the survival of Escherichia coli in the kidney.

Adhesins, Escherichia coli↗