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Biomedical subjects

C Bünger

Publications and source records attributed to C Bünger.

At least 73 records · Page 4Linked to original sources
PubMed1990

Displaced distal radius fractures. A comparative study of early results following external fixation, functional bracing in supination, or dorsal plaster immobilization.

A comparison of the radiographical and functional results after displaced distal radius fractures in 41 patients treated by external fixation (EF), 36 patients treated by functional bracing in supination (FUSU), and 49 patients treated by dorsal plaster immobilization (DPI) was performed. The rate of initial complications after EF was 53%, compared with 22% after FUSU and 14% after DPI. The radiographical result after EF was significantly better than after nonoperative treatment, but the functional result after 3 and 6 months demonstrated no significant difference between the three series. Consequently, EF and FUSU do not restore wrist function faster than conventional plaster treatment (DPI), but EF improves the radiographical result, though the rate of complications is higher.

Adult↗
PubMed1990

Microvascular morphology of bone in arthrosis. Scanning electron microscopy in rabbits.

The morphology of the bone microvasculature in rabbit arthrosis was studied by scanning electron microscopy (SEM) and related to changes in intraosseous pressure (IOP) and phlebographic appearance. Unilateral gonarthrosis was induced in 34 rabbits by immobilization of one knee in extension with a plastic splint for 5 weeks. Bilateral IOP recording in a subgroup of 12 rabbits demonstrated hypertension in arthrosis of 22 +/- 2.9 mmHg compared with 11 +/- 4.7 mmHg in control knees. Intraosseous phlebography in 13 rabbits showed a dilated vascular bed with prolonged clearance of contrast media. The morphology of normal microvasculature by SEM of intravascular methyl methacrylate casts in 9 rabbits was characterized by well-defined and well-demarcated sinusoids with only a few arteriovenous shunts, whereas in arthrosis substantial changes included fusion of sinusoids, leakage of cast material through the sinusoid walls, and development of numerous shunts. The study demonstrated profound microvascular morphologic changes that may reflect a vascular genesis for some of the bone changes in arthrosis.

Animals↗
PubMed1990

Synovitis reduced by inhibition of leukotriene B4. Carrageenan-induced gonarthritis studied in dogs.

The pathophysiologic significance of leukotriene B4 (LTB4) in arthritis was studied in dogs by unilateral intraarticular deposition of 15-hydroxy-eicosatetraenoic acid (15-HETE), an endogenous inhibitor of the formation and the effects of LTB4, in bilateral carrageenan-induced gonarthritis. LTB4 in synovial fluid was selectively inhibited in 15-HETE treated joints, the formation of prostaglandin E2 (PGE2) being largely unaffected. The clinical symptoms, intraarticular pressure, and extractable synovial fluid volume were reduced in treated joints. No effect could be discerned regarding blood flow in the synovial membrane, capsule, or juxta-articular bone as measured by tracer microspheres; and no effect on bone metabolism was found as judged by 99mTc-diphosphonate uptake. Thus, inhibition of LTB4 reduces joint exudation, but does not seem to interfere with changes in juxta-articular hemodynamics or bone metabolism following synovial inflammation.

Animals↗
PubMed1990

Hydroxyapatite coating enhances fixation of porous coated implants. A comparison in dogs between press fit and noninterference fit.

Intimate contact at the bone-porous surface interface is not always achievable in noncemented prosthetic implantation. We investigated the effect of hydroxyapatite (HA) coating on skeletal attachment in noninterference fit 4 weeks after implantation in 6 mature dogs. The push-out test of HA-coated implants surrounded by a 1-mm gap showed a twofold increased shear strength and fivefold increased shear stiffness compared with titanium alloy (Ti) coated implants. The fixation of Ti implants was reduced by two thirds when inserted in a gap as compared with press fit, whereas HA-coated implants in gap showed anchorage close to implants in press fit. Only minor differences were found between HA and Ti implants in press fit. Histomorphometric analysis showed a significant increase in bone in direct contact to HA-coated implant as compared with Ti implants inserted both in gap and press fit. The study indicates that tightness of surgical fit is an important factor for sufficient fixation of the implant. However, our results demonstrate that hydroxyapatite coating almost eliminates the negative influence of noninterference fit between bone and unloaded implant.

Animals↗
PubMed1989

Three-phase [99mTc]diphosphonate scintimetry in septic and nonseptic arthritis of the immature knee: an experimental investigation in dogs.

We compared the informative value of dynamic and static [99mTc]diphosphonate ([99mTc]DPD) scintimetry in early septic arthritis (SA) and chronic nonseptic arthritis (NSA) of the knee in puppies. SA (n = 10), induced by injection of Staphylococcus aureus into one knee, was examined after 48 h. NSA (n = 6) was induced by weekly intraarticular instillation of 1% carrageenan and examined at 2 and 12 weeks. Epiphyseal and metaphyseal count ratios (CRs) between experimental and control joint were calculated in an angiographic phase (0-20 s), a "blood pool" phase (20-256 s), and a bone uptake phase (2 hs). Control dogs (n = 4) had a CR of 1.0 in all regions and phases, the coefficients of variation being 0.06 and 0.03 in dynamic and static phases, respectively. In NSA, all scintimetric phases showed decreased metaphyseal uptake and largely unchanged epiphyseal uptake. Generally, SA exhibited vastly increased angiographic uptake in all regions and increased epiphyseal blood pool uptake, whereas delayed epiphyseal uptake varied and delayed metaphyseal uptake tended to decrease. Two septic joints had generalized reduction in dynamic uptake, probably owing to increased intraarticular pressure; in one of these, dynamic uptake in the distal femoral epiphysis (FE) was totally absent, suggesting temporary circulatory arrest during the dynamic scanning procedure. The use of regional dynamic and static [99mTc]DPD scintimetry increased the pathophysiologic and diagnostic value of joint scintigraphy, especially with respect to the early detection of SA and its avascular complications.

Animals↗
PubMed1989

15-Hydroxy-eicosatetraenoic acid (15-HETE) inhibits carrageenan-induced experimental arthritis and reduces synovial fluid leukotriene B4 (LTB4).

15-Hydroxy-eicosatetraenoic acid (15-HETE), a product of arachidonic acid, has no proinflammatory capacity, but can inhibit the formation and the chemotactic response of neutrophils to leukotriene B4 (LTB4), a potent mediator of inflammation. The purpose of the present study was to determine whether intraarticular administration of 15-HETE in carrageenan-induced acute arthritis might decrease the levels of LTB4 in synovial fluid and modify the arthritis. A bilateral acute knee joint arthritis was established in 7 dogs by intraarticular injections of carrageenan every third day. To the right joints, 15-HETE was administered both concomitantly with the carrageenan injections and continuously via an osmotic pump. In samples of synovial fluid obtained on day 0, 3 and 10 PGE2 and LTB4 were determined using reversed phase high performance liquid chromatography combined with radioimmunoassays and neutrophil chemokinesis. In the presence of 15-HETE the clinical severity of arthritis was significantly reduced and the volume of synovial effusate was decreased on an average by 42%. Furthermore, the relative number of neutrophils in histological sections of synovial tissue was decreased by 58%. Intraarticular caragheenan injections induced LTB4 formation, and maximum levels were obtained on day 3 (279.2 +/- 148.2 pg/joint). PGE2 was also present on day 3, but maximum levels were detected on day 10 (9.5 +/- 4.8 ng/joint). In joints injected with both carragheenan and 15-HETE the levels of LTB4 on days 3 and 10 were inhibited by 90% and 83%, respectively. For PGE2 a small but insignificant decrease was found on both day 3 and on day 10. These results show that LTB4 may be an important mediator of acute arthritis induced by carragheenan in dogs, and that intraarticular administration of 15-HETE can modify this arthritis by inhibiting LTB4 formation.

Animals↗
PubMed1989

Indomethacin and bone remodeling. Effect on cortical bone after osteotomy in rabbits.

Remodeling in cortical bone close to a plated tibial midshaft osteotomy was histomorphometrically evaluated in 32 rabbits. The animals were divided into two groups, one being treated with indomethacin (10 mg/kg per day) and the other receiving placebo. In the placebo-treated group, the remodeling activity was higher in the osteotomized leg compared with the intact leg. Two and 6 weeks after osteotomy, the number of resorptive and formative foci was reduced in the indomethacin-treated group compared with the placebo group. Porosity did not differ between the groups after 2 weeks; but after 6 weeks, it was reduced in the indomethacin-treated animals. Throughout the study, the bone formation rate did not differ between the two groups. This study demonstrates that indomethacin inhibits the remodeling of traumatized bone.

Animals↗
PubMed1989

Hemodynamic effects of knee-joint tamponade. 99mTc-diphosphonate scintimetry in growing dogs.

We studied the influence of joint effusion on juxtaarticular vascularity and bone metabolism of the immature knee in puppies by dynamic and static 99mTc-diphosphonate scintimetry. Unilateral joint tamponade of 10 KPa (75 mmHg), introduced by intraarticular dextran-70 infusion, resulted in quantitatively similar scintimetric changes in an angiographic Phase I (0-20 sec), a blood pool Phase II (20-256 sec), and a bone-uptake Phase III (2 h). The uptake was reduced by 20 percent in the distal femoral epiphysis, by 15 percent in the distal femoral growth plate in Phases II-III, and by 8 percent in the proximal tibial growth plate in Phase III. The main part of scintimetric changes during joint tamponade could be ascribed to altered epiphyseal and metaphyseal intraosseous hemodynamics.

Animals↗
PubMed1989

99mTc-DPD uptake in juvenile hemarthrosis. Scintimetry and autoradiography of the knee in dogs.

The pathogenesis of subchondral bone lesions and growth plate affection in hemophilic arthropathy was studied in puppies by means of repeated regional 99mTc-diphosphonate scintimetry and contact autoradiography. Unilateral hemarthrosis of the knee was induced by biweekly intraarticular injections of autologous blood for 12 weeks. Hemarthrosis caused an early (2 to 4 weeks) decrease in uptake of 99mTc-diphosphonate in the juxtaarticular growth plates (ratio 0.7) and a delayed (8 to 10 weeks) increase in epiphyseal uptake (ratio 1.5). In a recovery phase after hemarthrosis, growth plate uptake returned to normal, while the epiphyseal uptake remained elevated for 8 to 10 weeks. By contact autoradiography, the growth plate uptake was localized to the calcification layer at the metaphyseal aspect of the growth plates, while the epiphyseal uptake mainly was seen in the thin subchondral and subsynovial bone layer and around osteophytes. The changes in uptake of 99mTc-diphosphonate following hemarthrosis for 3 months were reversible and could be ascribed to the presence of synovial inflammation.

Animals↗
PubMed1989

Effect of indomethacin on regulation of juxta-articular bone blood-flow during joint tamponade. An experimental study in puppies.

Prostaglandins are vasoactive substances which are assumed to play a major role in bone metabolism and bone repair. The purpose of the present study was to investigate the effect of indomethacin on the control of epiphyseal bone blood-flow. By means of simultaneous intra-osseous pressure (IOP) and regional blood flow (RBF) measurements in the distal femoral epiphysis (DFE), aspects of vascular control mechanisms in the distal femoral epiphysis were investigated during knee joint tamponade (50% of mean arterial pressure) before and after administration of indomethacin 7.5 mg/kg. Six dogs aged 3-4 months were investigated in fentanyl anaesthesia. Knee joint tamponade resulted in a significant increase in IOP and calculated venous resistance in the DFE, while no significant changes in regional blood-flow or arterial resistance were encountered. Administration of indomethacin did not affect this reaction. The results suggests that indomethacin 7.5 mg/kg does not influence the regulation of epiphyseal blood-flow during elevation of joint pressure indicating that prostaglandins play only a minor or no role in this regulation.

Animals↗
PubMed1988

The effect of i.v. indomethacin on the gastric mucosal electrical potential difference and blood flow in anaesthetized dogs.

Indomethacin inhibits prostaglandin synthesis and causes gastric mucosal damage. The correlation between the gastric mucosal function and gastric blood flow was investigated. The intragastric liquid junction corrected potential difference (PD) across the stomach wall was used to characterize the gastric mucosal function. Mucosal blood flow was determined by the radiolabelled microsphere technique. Seven dogs were anaesthetized, intragastric PD was measured continuously and blood flow determined at basal condition during sympathetic activation, and after IV indomethacin (7.5 mg/kg). PD was unchanged during the basal period and during mild sympathetic activation. After indomethacin PD was reduced significantly (-40 +/- 6 mV to -20 +/- 5 mV, measured with gastric lumen negative, mean and SD, P less than 0.05). Mucosal blood flow decreased during sympathetic activation and a further significant reduction was seen after indomethacin. PD and flow reductions correlated (R = 0.92). As indomethacin given IV caused a parallel impairment of gastric mucosal function and blood flow, part of the indomethacin-related mucosal damaging effects might be due to the flow reduction.

Animals↗
PubMed1988

Carrageenan-induced coxitis in puppies.

We studied the influence of chronic synovitis and joint effusion on the blood supply and growth of the immature femoral head in 12 puppies. Twelve weekly intraarticular injections of Carrageenan solution caused unilateral coxitis with caput magnum formation. Joint pressures in the neutral position were 0.9 kPa in the coxitis hips and -0.5 kPa in the contralateral hips. The joint capsule in coxitis showed hyperemia as measured by tracer microsphere technique. In nonmedicated, awake, standing dogs there was hyperemia of both the femoral head epiphysis and the joint capsule. In all the dogs, acetabular and proximal femoral metaphyseal blood flow was unchanged. In the control group, repeated cannulation and injection of normosaline did not change the hemodynamics, joint pressure, or femoral head size. We found no evidence of femoral head ischemia in coxitis with moderate chronic elevation of resting joint pressure.

Animals↗
PubMed1987

Tissue vitality in septic gonitis. 99mTc-DPD scintimetry in puppies.

After a single intraarticular injection of 10(9) Staphylococcus aureus in 12 puppies, septic arthritis developed in all the experimental knees after 48 hours. A considerable variability in scintigraphic appearance was observed. The juxtaarticular growth plates showed either unchanged or slightly decreased uptake except in 1 dog exhibiting a definite increase in tracer uptake. The epiphyseal uptake showed no consistent pattern. The intraarticular pressure of the arthritic joints increased significantly, but was not related to the tracer uptake pattern. We conclude that delayed joint scintigraphy as a single investigation in early septic arthritis does not provide diagnostic information and may be misleading.

Animals↗
PubMed1987

Bone repair inhibited by indomethacin. Effects on bone metabolism and strength of rabbit osteotomies.

We measured mineral content, maximum bending strength, and regional blood flow after tibial osteotomy fixed with a small metal plate in 38 rabbits. Half of the animals were treated with indomethacin (10 mg/kg/day) while the other half served as controls. After 2 and 6 weeks, the bone mineral content and maximum bending strength were lower in the indomethacin group when compared with the controls. Compared with the controls, the blood flow at the osteotomy site was decreased after 2 weeks and increased after 6 weeks in the indomethacin-treated animals. Inhibition of blood flow increase by indomethacin medication in the early period following osteotomy, as well as retarded bone healing, are probably caused by inhibition of the inflammatory reaction.

Animals↗
PubMed1986

Fibrin sealant in bone transplantation. No effects on blood flow and bone formation in dogs.

To study bone formation and regional blood flow following the use of fibrin sealant in autologous cancellous bone transplantation, a dog model was developed. In 18 dogs, a standardized defect in both tibiae was filled with an autologous iliac crest graft. On one side, the bone chips were mixed with fibrin sealant while the other side served as control. After 1, 2 and 3 weeks the blood flow of the transplant was calculated and the new bone formed evaluated histomorphometrically. Generally, the highest blood flow rates and most intensive new bone formation were observed at 2 weeks postoperatively. Fibrin sealant did not alter blood flow or new bone formation, but a tendency to diminished new bone formation was found in some grafts. Our study does not support the application of fibrin sealant in ordinary cancellous bone grafting.

Animals↗