Lars M Bjursten | Lund University (original) (raw)

Papers by Lars M Bjursten

Scandinavian Journal of Plastic and Reconstructive Surgery and Hand Surgery, 1981

Rabbits skin folds were placed in plexiglass chambers enabling control of the skin fold temperatu... more Rabbits skin folds were placed in plexiglass chambers enabling control of the skin fold temperature during cuff compression (200 mmHg) for 4 hours. In 10 animals the skin folds were kept at 36 degrees C - in another 10 animals the skin fold temperature was lowered to 10 degrees C. To quantitate the skin injury caused by the pressure ischemia a standardized wound was made, and immediately closed, after release of pressure. Control wounds were made in normal skin. Seven days later the mechanical strength of the wounds was tested by determination of breaking load. There was no significant difference in breaking load between the wounds made in normal skin and in the skin folds kept at 10 degrees C, whereas the breaking loads was significantly decreased in the wounds made in skin folds kept at 36 degrees C, i.e. normal skin temperature, compared with the controls. Thus, the results show that cooling may preserve the reparative capacity in skin subjected to pressure ischemia. It is assumed that this effect is related to a lowered cell metabolism during the ischemia. It may also be concluded that the pressure (mechanical) injury, being the same in both temperature groups, is less important than the ischemic injury.

ABSTRACT Macrophage mechanosensitivity has been proposed to influence the body’s response to soft... more ABSTRACT Macrophage mechanosensitivity has been proposed to influence the body’s response to soft tissue implants due to micromotion which imposes tissue deformation-induced pressure gradients. Previously, pulsatile pressures have been shown to alter rates of superoxide production by macrophages. Because superoxide release affects cell viability, this study explored the possibility that pulsatile pressure exposure influences macrophage death. For this purpose a custom system was used to expose HL-60-derived macrophages to controlled pulsatile pressures. Compared to cells under atmospheric (control) pressures, macrophages exposed to 7.5/2.5 mmHg for 6, but not 16, hours exhibited reduced cell numbers. This transient, cell detachment occurred in the absence of significant changes in cell death. Interestingly, similar time-dependent reductions in cell attachment were observed when macrophages were subjected to superoxide dismutase under control conditions to mimic pressure-induced attenuation of superoxide release. Combined, the results of this ongoing study suggest that pressure modulates macrophage adhesion via a mechanosensitive superoxide-dependent effect.

The International journal of oral & maxillofacial implants

Macrophage mechanosensitivity has been proposed to influence the body’s response to soft tissue i... more Macrophage mechanosensitivity has been proposed to influence the body’s response to soft tissue implants due to micromotion which imposes tissue deformation-induced pressure gradients. Previously, pulsatile pressures have been shown to alter rates of superoxide production by macrophages. Because superoxide release affects cell viability, this study explored the possibility that pulsatile pressure exposure influences macrophage death. For this purpose a custom system was used to expose HL-60-derived macrophages to controlled pulsatile pressures. Compared to cells under atmospheric (control) pressures, macrophages exposed to 7.5/2.5 mmHg for 6, but not 16, hours exhibited reduced cell numbers. This transient, cell detachment occurred in the absence of significant changes in cell death. Interestingly, similar time-dependent reductions in cell attachment were observed when macrophages were subjected to superoxide dismutase under control conditions to mimic pressure-induced attenuation o...

The objective of this study was to assess the sensitivity of macrophages to fluid pressures as a ... more The objective of this study was to assess the sensitivity of macrophages to fluid pressures as a first step towards identifying parameters that modulate the tissue implant interface. We hypothesized that fluid pressure at an implant interface influences macrophage activity. To address this hypothesis, we assessed superoxide production by, and the F-actin cytoskeletal organization of, HL-60 derived macrophages after a 2 h exposure to multiple pressure oscillations by varying either their mean (MP) (540 mm Hg), pulse pressure (PP) (0-7.5 mm Hg), or frequency (0-1.5Hz). From these experiments, we observed significantly (p<0.05) reduced superoxide production by the cells under all conditions tested. Interestingly, the reductions in superoxide release were independent of the MPs and oscillation frequencies, and instead depended on the PPs. We also observed a reorganization of the cytoskeleton in cells exposed to 20 mm Hg MP at PPs ranging from 0-7.5 mm Hg at 1.5 Hz relative to paired ...

Proceedings of the First Joint BMES/EMBS Conference. 1999 IEEE Engineering in Medicine and Biology 21st Annual Conference and the 1999 Annual Fall Meeting of the Biomedical Engineering Society (Cat. No.99CH37015), 1999

The tissue response to implanted polyethylene discs was evaluated. Cells with increased membrane ... more The tissue response to implanted polyethylene discs was evaluated. Cells with increased membrane permeability could be identified using fluorescence microscopy by injection of propidium iodide prior to the killing of the rats. Cell death was verified by detection of DNA fragmentation. Early, a considerable amount of the cells close to the implant surface were stained with propidium iodide and especially

physica status solidi (a), 2000

Restorative neurology and neuroscience, 1997

Gaps, 10 mm wide, in rat sciatic nerves were bridged by bioartificial nerve grafts consisting of ... more Gaps, 10 mm wide, in rat sciatic nerves were bridged by bioartificial nerve grafts consisting of a silicone tube containing seven longitudinally placed synthetic filaments, which were expected to serve as a scaffold for axonal growth. The filaments were made of non-resorbable material (polyamide [Ethilon®]) or resorbable material (polydioxanon [PDS®], polyglactin [Vicryl®] or catgut). The purpose was to study the influence of resorbable materials on axonal regeneration and to choose, in the long term, the best filament material among the four. After 3 and 6 months, histological techniques were used to study the regenerated nerve structure. The total axon number in the nerve segment distal to the silicone chamber was counted in all specimens at 6 months. The histological findings were different depending on the filament materials; all the three resorbable materials showing significantly larger numbers of axons than polyamide (non-resorbable). All materials were covered with several l...

Journal of materials science. Materials in medicine, 1997

A 10 mm gap in a rat sciatic nerve was bridged by a bioartificial nerve graft consisting of a sil... more A 10 mm gap in a rat sciatic nerve was bridged by a bioartificial nerve graft consisting of a silicone tube containing seven longitudinally placed filaments made of non-resorbable material (polyamide [Ethilon]) or resorbable materials (polydioxanon [PDS], polyglactin [Vicryl] or catgut). The purpose was to study the tissue reaction induced by the four different types of materials. At 4 weeks an immunocytochemical technique, using ED1 and ED2 monoclonal antibodies, was used to study the presence and location of macrophages. A large number of macrophages were found accumulating on the surface of catgut and polyglactin, while few were found on the surface of polyamide and polydioxanon filaments. It is concluded that the cell layers on the filament surface mainly consisted of ED1 positive cells and their thickness depends on the filament materials.

Journal of materials science. Materials in medicine, 1999

This study investigates the importance of implant surface topography on soft tissue response. The... more This study investigates the importance of implant surface topography on soft tissue response. The tissue response in the rat abdominal wall to discs of low density polyethylene with smooth to coarse surfaces was evaluated after one, six or 12 weeks. Capsule thickness and immunohistochemical quantification of monocytes-macrophages were used as measures. The macrophage specific antibody ED1 was used for identification of newly recruited macrophages and the ED2 antibody for the mature tissue macrophages. The smoother surfaces gave a thicker capsule than the rougher surfaces, and at one week also larger total numbers of cells and ED1 positive macrophages at interface. The capsule thickness increased over time for the smooth and intermediate surface topographies. In contrast, the cell numbers generally decreased over time. In conclusion, a coarse surface elicited lesser tissue reaction compared with a smooth surface.

Journal of materials science. Materials in medicine, 1998

Implants of commercially pure titanium and polytetrafluoroethylene (PTFE) were inserted in the ra... more Implants of commercially pure titanium and polytetrafluoroethylene (PTFE) were inserted in the rat abdominal wall for 1, 6 or 12 wk. The foreign body reaction was evaluated by immunohistochemical quantification of monocytes/macrophages and by the thickness of the foreign-body capsule. At all time intervals, the majority of interfacial cells were ED1-positive while ED2-positive cells were localized deeper in the tissue. Neither titanium nor PTFE displayed a significant change in capsule thickness over time. The total cell numbers decreased overtime for both types of material. At 12 wk the PTFE implants, compared to titanium, were surrounded by a significantly thicker reactive capsule with larger total cell numbers. No significant differences were seen in the macrophage subset response between the two types of implants. Thus, the present study showed differences between titanium and PTFE at 12 wk but not at earlier time points.

Scandinavian journal of plastic and reconstructive surgery and hand surgery / Nordisk plastikkirurgisk forening [and] Nordisk klubb for handkirurgi, 1997

Gaps 10 mm wide in the sciatic nerves of 64 rats were bridged by bioartificial nerve grafts consi... more Gaps 10 mm wide in the sciatic nerves of 64 rats were bridged by bioartificial nerve grafts consisting of a silicone tube containing seven longitudinally placed filaments made of non-absorbable, (polyamide [Ethilon]) or absorbable, material (polydioxanone [PDS], polyglactin [Vicryl], and catgut). The purpose was to study the organisation of axonal growth inside the tube along such filaments. After two and four weeks histological techniques were used to study the contents of the tube and at four weeks immunohistological techniques were used to confirm the presence of axons distal to the tube. In all experimental groups axons had traversed the tube and reached the distal segment after four weeks. Inside the tube axons were organised in multiple minifascicles in all groups, but there were no axons growing in direct contact with the filaments. We conclude that resorbable filaments placed inside a silicone tube do not disturb axonal growth across the tube.

Immunology, 1983

Immune complexes were formed in vitro with antibodies obtained from rabbits immunized with bovine... more Immune complexes were formed in vitro with antibodies obtained from rabbits immunized with bovine serum albumin in Freund's complete (FCA) or incomplete (FIA) adjuvant. The antibodies were mixed with different amounts of antigen. Immune complexes formed at maximum precipitation proportions were efficient in complement activation, whereas immune complexes formed at antigen excess had weak complement-activating properties. When injected into rabbit knee joints, the immune complexes formed at maximum precipitation proportions with FCA or FIA antibodies caused a moderate leucocyte migration into the joints with maximum cell counts 6-8 hr after injection. Injection into the joints of immune complexes formed with FCA antibodies at antigen excess induced a pronounced leucocyte migration with maximum numbers 18 hr after injection. Immunofluorescent studies indicated that these immune complexes became associated with the leucocyte membrane, whereas immune complexes formed at maximum prec...

Infection and immunity, 1984

The fitness between bacterial adhesins and target cell receptors, determining bacterial adherence... more 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...

The American journal of otology, 1988

Some patients with hearing impairment cannot use conventional hearing aids. One solution for thes... more 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 t...

Scandinavian Journal of Plastic and Reconstructive Surgery and Hand Surgery, 1986

An experimental model is presented that allows qualitative as well as quantitative studies of the... more 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.