PubMed Health⌕ Search

Biomedical subjects

G Duda

Publications and source records attributed to G Duda.

At least 19 recordsLinked to original sources
PubMed2003

Temporal profile of microvascular disturbances in rat tibial periosteum following closed soft tissue trauma.

BACKGROUND AND AIMS: Bone devascularization due to impaired periosteal perfusion following fracture with severe soft tissue trauma has been proposed to precede and underlie perturbed bone healing. The extent and temporal relationship of periosteal microcirculatory deteriorations after severe closed soft tissue injury (CSTI) are not known. We hypothesized that periosteal microcirculation is adversely affected and the manifestation of trauma-initiated microvascular impairment in periosteum is substantially prolonged following CSTI. MATERIAL AND METHODS: Using the controlled-impact injury device, we induced standardized CSTI in the tibial compartment of 35 isoflurane-anesthetized rats. Following the trauma the rats were assigned to five groups, differing in time of analysis (2 h, 24 h, 48 h, 1 and 6 weeks). Non-injured rats served as controls. Before the metaphyseal/diaphyseal periosteum was surgically exposed, intramuscular pressure within tibial compartment was measured. Using intravital fluorescence microscopy (IVM) we studied the microcirculation of the tibial periosteum. We calculated the edema index (EI) by measuring the skeletal muscle wet-to-dry weight ratio (EI = injured limb/contralateral limb). RESULTS: Microvascular deteriorations of periosteal microhemodynamics caused by isolated CSTI were reflected by persistent decrease in nutritive perfusion, markedly prolonged increase in microvascular permeability associated with increasingly sustained leukocyte rolling and adherence throughout the entire study period, mostly pronounced 48 h after the trauma. Peak level in capillary leakage coincided with the maximum leukocyte adherence, tissue pressure, and edema. Microcirculation of tibial periosteum in control rats demonstrated a homogeneous perfusion with no capillary or endothelial dysfunction. CONCLUSION: Isolated CSTI in absence of a fracture exerts long-lasting disturbances in periosteal microcirculation, suggesting a delayed temporal profile in manifestation of CSTI-induced periosteal microvascular dysfunction and inflammation. These observations may have therapeutic implications in terms of preserving periosteal integrity and considering the interaction of skeletal muscle damage and periosteal microvascular injury during management of musculoskeletal trauma.

Animals↗
PubMed2002

Dose-dependent effects of combined IGF-I and TGF-beta1 application in a sheep cervical spine fusion model.

Combined IGF-I and TGF-beta1 application by a poly-(D,L-lactide) (PDLLA) coated interbody cage has proven to promote spine fusion. The purpose of this study was to determine whether there is a dose-dependent effect of combined IGF-I and TGF-beta1 application on intervertebral bone matrix formation in a sheep cervical spine fusion model. Thirty-two sheep underwent C3/4 discectomy and fusion. Stabilisation was performed using a titanium cage coated with a PDLLA carrier including no growth factors in group 1 ( n=8), 75 micro g IGF-I plus 15 micro g TGF-beta1 in group 2 ( n=8), 150 micro g IGF-I plus 30 micro g TGF-beta1 in group 3 ( n=8) and 300 micro g IGF-I plus 60 micro g TGF-beta1 in group 4 ( n=8). Blood samples, body weight and temperature were analysed. Radiographic scans were performed pre- and postoperatively and after 1, 2, 4, 8, and 12 weeks. At the same time points, disc space height and intervertebral angle were measured. After 12 weeks, the animals were killed and fusion sites were evaluated using quantitative computed tomographic (CT) scans to assess bone mineral density, bone mineral content and bony callus volume. Biomechanical testing was performed and range of motion, and neutral and elastic zones were determined. Histomorphological and histomorphometrical analysis were carried out and polychrome sequential labelling was used to determine the time frame of new bone formation. In comparison to the group without growth factors (group 1), the medium- and high-dose growth factor groups (groups 3 and 4) demonstrated a significantly higher bony callus volume on CT scans, a higher biomechanical stability, an advanced interbody bone matrix formation in histomorphometrical analysis, and an earlier bone matrix formation on fluorochrome sequence labelling. Additionally, the medium- and high-dose growth factor groups (groups 3 and 4) demonstrated a significantly higher bony callus volume, a higher biomechanical stability in rotation, and an advanced interbody bone matrix formation in comparison to the low-dose growth factor group (group 2). No significant difference could be determined between the medium- and the high-dose growth factor groups (groups 3 and 4, respectively). The local application of IGF-I and TGF-beta1 by a PDLLA-coated cage significantly improved results of interbody bone matrix formation in a dose-dependent manner. The best dose-response relationship was achieved with the medium growth factor dose (150 micro g IGF-I and 30 micro g TGF-beta1). With an increasing dose of these growth factors, no further stimulation of bone matrix formation was observed. Although these results are encouraging, safety issues of combined IGF-I and TGF-beta1 application for spinal fusion still have to be addressed.

Animals↗
PubMed2002

Comparison of BMP-2 and combined IGF-I/TGF-ss1 application in a sheep cervical spine fusion model.

Growth factors have proven to promote spine fusion. However, no comparative evaluation of growth factors in spinal fusion has yet been performed. The purpose of this study was to compare the efficacy and safety of combined IGF-I and TGF-ss1 application with BMP-2 application and autologous cancellous bone graft at an early time point in a sheep cervical spine fusion model. Thirty-two sheep underwent C3/4 discectomy and fusion. They were divided into four groups, according to their treatment: group 1, titanium cage ( n=8); group 2, titanium cage filled with autologous cancellous iliac crest bone grafts ( n=8); group 3, titanium cage coated with a poly-(D,L-lactide) (PDLLA) carrier including BMP-2 (5% w/w) ( n=8); group 4, titanium cage coated with a PDLLA carrier including IGF-I (5% w/w) and TGF-ss1 (1% w/w) ( n=8). Blood samples, body weight and temperature were analysed. Radiographic scans were performed pre- and postoperatively and after 1, 2, 4, 8 and 12 weeks. At the same time points, disc space height and intervertebral angle were measured. After 12 weeks, the animals were killed and fusion sites were evaluated using functional radiographic views in flexion and extension. Quantitative computed tomographic scans were performed to assess bone mineral density, bone mineral content and bony callus volume. Biomechanical testing was carried out and the values for range of motion, and neutral and elastic zone were determined. Histomorphological and histomorphometrical analysis were performed and polychrome sequential labelling was used to determine the time frame of new bone formation. The results showed that, in comparison to the group treated with the cage alone (group 1), the cage plus BMP-2 group (group 3) and the cage plus IGF-I and TGF-ss1 group (group 4) demonstrated a significantly higher fusion rate in radiographic findings, a higher biomechanical stability, a more advanced interbody fusion in histomorphometrical analysis, and an accelerated interbody fusion on fluorochrome sequence labelling. In comparison to the bone graft group (group 2), the BMP-2 (group 3) and IGF-I/TGF-ss1 group (group 4) showed significantly less residual motion on functional radiographic evaluation, higher bone mineral density of the callus and higher biomechanical stability in extension, rotation and bending. The BMP-2 group showed significantly less residual motion on functional radiographic evaluation and higher intervertebral bone matrix formation on fluorochrome sequence labelling at 9 weeks in comparison to the IGF-I/TGF-ss1 group. In contrast, the IGF-I/TGF-ss1 group showed a significantly higher bone mineral density of the callus than the BMP-2 group. In comparison to the autologous cancellous bone graft group, both growth factors (BMP-2 and combined IGF-I and TGF-ss1) significantly improved the biomechanical results of interbody fusion. No systemic side effects were observed for either growth factor. On the basis of these preliminary results, it would appear that combined IGF-I/TGF-ss1 application yields equivalent results to BMP-2 application at an early time point in anterior sheep cervical spine fusion.

Animals↗
PubMed2002

[Experimental fusion of the sheep cervical spine. Part I: Effect of cage design on interbody fusion].

INTRODUCTION: There has been a rapid increase in the use of interbody fusion cages as an adjunct to spondylodesis, although experimental data are lacking. A sheep cervical spine interbody fusion model was used to determine the effect of different cage design parameters (endplate-implant contact area, maximum contiguous pore) on interbody fusion. MATERIAL AND METHOD: IN VITRO EVALUATION: 24 sheep cadaver specimens (C2-C5) were tested in flexion, extension, axial rotation, and lateral bending with a nondestructive flexibility method using a nonconstrained testing apparatus. Four different groups were examined: (1) control group (intact) ( n=24), (2) autologous tricortical iliac crest bone graft ( n=8), (3) Harms cage ( n=8), and (4) SynCage-C ( n=8). IN VIVO EVALUATION: 24 sheep underwent C3/4 discectomy and fusion: group 1: autologous tricortical iliac crest bone graft ( n=8), group 2: Harms cage filled with autologous cancellous iliac crest bone grafts ( n=8), and group 3: SynCage-C filled with autologous cancellous iliac crest bone grafts ( n=8). Radiographic scans were performed pre- and postoperatively and after 1, 2, 4, 8, and 12 weeks, respectively. At the same time points, disc space height (DSH), height index (HI), intervertebral angle (IVA), and endplate angle (EA) were measured. After 12 weeks the animals were killed and fusion sites were evaluated using biomechanical testing in flexion, extension, axial rotation, and lateral bending. Additionally, histomorphological and histomorphometrical analyses were performed. RESULTS: Over a 12-week period the cage groups showed significantly higher values for DSH, HI, IVA, and EA compared to the bone graft. In vivo stiffness was significantly higher for the tricortical iliac crest bone graft and Harms cage than in vitro stiffness. However, there was no difference between in vitro and in vivo stiffness of the SynCage-C. Histomorphometrical evaluation showed a more progressed bone matrix formation in the Harms cage group than in both other groups. CONCLUSION: The parameter endplate-implant contact area was not able to determine subsidence of cages. In contrast, the maximum contiguous pore of a cage significantly correlates with interbody bone matrix formation inside the cage. Additionally, there was no correlation between in vitro and in vivo stiffness of interbody fusion cages. Therefore, biomechanical in vitro studies are not able to determine in vivo outcome of fusion cages. Animal experimental evaluations of interbody fusion cages are essential prior to clinical use.

Animals↗
PubMed2002

[Experimental fusion of the sheep cervical spine. Part II: Effect of growth factors and carrier systems on interbody fusion].

INTRODUCTION: A sheep cervical spine interbody fusion model was used to determine the effect of different carriers and growth factors on interbody bone matrix formation. The purpose of this study was to compare the efficacy and safety of combined IGF-I and TGF-beta1 application with BMP-2 application in spinal fusion. Additionally, a new poly (D, L-lactide) carrier system was compared to a collagen sponge carrier. METHOD: Forty sheep underwent C3/4 discectomy and fusion: group 1: titanium cage ( n=8), group 2: titanium cage coated with a PDLLA carrier (n=8), group 3: titanium cage coated with a PDLLA carrier including BMP-2 ( n=8), group 4: titanium cage with a collagen carrier including BMP-2 ( n=8), and group 5: titanium cage coated with a PDLLA carrier including IGF-I and TGF-beta1 ( n=8). Blood samples, body weight, and temperature were analyzed. Radiographic scans were performed pre- and postoperatively and after 1, 2, 4, 8, and 12 weeks, respectively. At the same time points, disc space height (DSH) and intervertebral angle (IVA) were measured. After 12 weeks the animals were killed and fusion sites were evaluated using functional radiographic views in flexion and extension. Quantitative computed tomographic scans (QCT) were performed to assess bone mineral density (BMD), bone mineral content (BMC), and bony callus volume (BCV). Biomechanical testing was carried out in flexion, extension, axial rotation, and lateral bending. Range of motion (ROM), neutral zone (NZ), and elastic zone (EZ) were determined. Histomorphological and histomorphometrical analyses were performed and polychrome sequential labeling was used to determine the time frame of new bone formation. RESULTS: In comparison to the non-coated cages, all PDLLA-coated cages showed significantly higher values for BMD of the callus and bone volume/total volume ratio. In comparison to the cage groups (groups 1 and 2), the cage plus BMP-2 (groups 3 and 4) and the cage plus IGF-I and TGF-beta1 group (group 5) demonstrated a significantly higher fusion rate in radiographic findings, a higher biomechanical stability, an advanced interbody fusion in histomorphometric analysis, and an accelerated interbody fusion on fluorochrome sequence labeling. BMP-2 application by the PDLLA carrier system (group 3) demonstrated significantly higher bony callus volume than BMP-2 application by a collagen sponge carrier (group 4). The BMP-2 group (group 3) showed significantly lower residual motion on functional radiographic evaluation and higher intervertebral bone matrix formation on fluorochrome sequence labeling at 9 weeks in comparison to the IGF-I/TGF-beta1 group (group 5). In contrast, the IGF-I/TGF-beta1 group (group 5) showed a significantly higher bone mineral density of the callus than the BMP-2 group (group 3). CONCLUSION: PDLLA coating of cervical spine interbody fusion cages as a delivery system for growth factors was effective and safe. In comparison to the collagen sponge carrier, the new PDLLA carrier system was able to improve results of interbody bone matrix formation. Both growth factors (BMP-2 and combined IGF-I and TGF-beta1) significantly accelerated results of interbody fusion. Based on these preliminary results, the combined IGF-I/TGF-beta1 application yields results equivalent to BMP-2 application at an early time in anterior sheep cervical spine fusion.

Animals↗
PubMed2001

Biomechanical comparison of cervical spine interbody fusion cages.

STUDY DESIGN: An in vitro biomechanical study of cervical spine interbody fusion cages using a sheep model was conducted. OBJECTIVES: To evaluate the biomechanical effects of cervical spine interbody fusion cages, and to compare three different cage design groups. SUMMARY AND BACKGROUND DATA: Recently, there has been a rapid increase in the use of cervical spine interbody fusion cages as an adjunct to spondylodesis. These cages can be classified into three design groups: screw, box, or cylinder designs. Although several comparative biomechanical studies of lumbar interbody fusion cages are available, biomechanical data for cervical spine constructs are lacking. Additionally, only limited data are available concerning comparative evaluation of different cage designs. METHODS: In this study, 80 sheep cervical spines (C2-C5) were tested in flexion, extension, axial rotation, and lateral bending with a nondestructive stiffness method using a nonconstrained testing apparatus. Three-dimensional displacement was measured using an optical measurement system (Qualysis). Complete discectomy (C3-C4) was performed. Cervical spine interbody fusion cages were implanted according to manufacturers' information. Eight spines in each of the the following groups were tested: intact, autologous iliac bone graft, two titanium screws (Novus CTTi; Sofamor Danek, Koln, Germany), two titanium screws (BAK-C 8 mm; Sulzer Orthopedics, Baar, Switzerland), one titanium screw (BAK-C 12 mm; Sulzer Orthopedics), carbon box (Novus CSRC; Sofamor Danek), titanium box (Syncage; Synthes, Bochum, Germany), titanium mesh cylinder (Harms; DePuy Acromed, Sulzbach, Germany), titanium cylinder (MSD; Ulrich, Ulm, Germany), and titanium cylinder (Kaden; BiometMerck, Berlin, Germany). The mean apparent stiffness values were calculated from the corresponding load-displacement curves. Additionally, cage volume and volume-related stiffness was determined. RESULTS: After cervical spine interbody fusion cage implantation, flexion stiffness increased, as compared with that of the intact motion segment. On the contrary, rotation stiffness decreased after implantation of a cervical spine interbody fusion cage, except for the Novus CSRC, Syncage, and Kaden-Cage. If two screws were inserted (Novus CTTi and BAK-C 8 mm), there was no significant difference in flexion stiffness between screw and cylinder design groups. If one screw was inserted (BAK-C 12 mm), flexion stiffness was higher for cylinder designs (P < 0.05). Extension and bending stiffness were always higher with cylinder designs (P < 0.05). Volume-related stiffness for flexion extension and bending was highest for the Harms cage (P < 0.05). There was no difference for rotation volume-related stiffness between Harms and Syncage. CONCLUSIONS: The biomechanical results indicate that design variations in screw and cylinder design groups are of little importance. In this study, however, cages with a cylinder design were able to control extension and bending more effectively than cages with a screw design.

Animals↗
PubMed2000

[Dorsal oblique pelvic fixator: development and biomechanical testing].

In haemodynamically unstable patients with an unstable pelvic ring injury the primary stabilisation of the pelvis and thus reduction of pelvic volume is important for the success of the treatment. The pelvic C-clamp is an approved emergency device for these unstable pelvic ring injuries. A secondary procedure though is necessary in most of the cases with a hig rate of wound problems in already traumatized soft tissue areas. The ventrally placed external fixator is a simple and quick procedure with little soft tissue damage. Though primary stability is sufficient even for C-type injuries, biomechanic stability of the posterior pelvic ring is often insufficient for mobilization. Based on biomechanic considerations, a new dorsal oblique pelvic external fixator was developed for pelvic C-type injuries. With the advantages of the supraacetabular fixator and two additional Schanz screws the ventral fixator should stabilize the posterior pelvic ring with comparable stability to the pelvic C-clamp. A primary and already definitive minimal invasive stabilization of the posterior pelvic ring was the aim. In the first series several variations of this asymmetric fixator with two different Schanz screw applications were tested biomechanically. In a second series the favorite version was tested versus the supraacetabular fixator and the pelvic C-clamp. Both of the biomechanic test series were performed with artificial pelves in the one leg stance model in the material testing machine. SI disruption and sacral fracture were the posterior instability types in 6 pelves each. There was no statistically significant difference between the dorsal oblique fixator and the pelvic C-clamp. But the new fixator was significantly more stable than the supraacetabular fixator or the new fixator without pretension.

Biomechanical Phenomena↗
PubMed2000

Comparison of three different plating techniques for the dorsum of the distal radius: a biomechanical study.

Three different plating techniques were used on experimentally produced dorsally displaced distal radius fractures in cadavers and were tested in 4-point bending: a AO 3.5-mm T plate (group 1), two 2. 0-mm titanium plates 60 degrees to each other (group 2), and the AO pi plate (group 3). A metaphyseal defect was simulated by a dorsally open wedge osteotomy. The tests show that the 2-mm double-plating technique has superior stiffness and statistically equivalent bending and bone gap to failure compared with the AO 3.5-mm T plate or the pi plate when applied to the unstable distal radius fracture model. (J Hand Surg 2000; 25A:29-33.

Biomechanical Phenomena↗
PubMed1999

novel Award Second Prize Paper. Functional monitoring during rehabilitation following anterior cruciate ligament reconstruction.

OBJECTIVE: It was hypothesized that testing of ambulatory function and more demanding activities were more appropriate predictors of dynamic knee function before and after reconstruction of the anterior cruciate ligament than conventional measures of functional evaluation. It was assumed that assessment of dynamic plantar pressure distribution would represent a practical tool for guidance of the rehabilitation process after anterior cruciate ligament reconstruction. DESIGN: In a prospective study, 10 patients with isolated anterior cruciate deficiency were examined before and after replacement of the anterior cruciate (6, 12, 24 weeks) in a standardized technique. BACKGROUND: Today, functional assessment following anterior cruciate ligament reconstruction relies on clinical examination supplemented by instrumented testing of knee laxity and on isokinetic evaluation of muscle performance. Gait analysis has not been used as a quantitative measure of rehabilitation progress after surgery. METHODS: All patients were subjected to the same physiotherapy protocol. The clinical results were documented using the International Knee Documentation Committee (IKDC) protocol and the degree of knee laxity by an instrumented anterior drawer test. Muscular performance was evaluated by isokinetic testing. Dynamic pedography (EMED-SF 4) was performed to compare the non-injured and the operated leg during level walking and while descending stairs. RESULTS: Gait performance six weeks after surgery tended to be inferior to preoperative and late postoperative values. While the slight increase of maximum knee extensor torque in the operated leg and the improvement of the IKDC score during the rehabilitation period were not statistically significant, a significantly decreased gait asymmetry could be observed 12 weeks after surgery. The descending stairs test revealed functional deficits better than level walking. The latter test exhibited a strong correlation with the preoperative IKDC level and the maximum knee extensor deficit at 60 degrees /s. CONCLUSIONS: Dynamic pedography during level walking and while descending stairs is a valuable tool for monitoring the rehabilitation process after anterior cruciate ligament reconstruction. RELEVANCE: Due to the better resolution of functional deficits compared with indirect measures of function (isokinetic testing) assessment of the plantar pressure distribution may provide a more individualized adaptation for the rehabilitation program.

Adult↗
PubMed1997

[Disorders of gastric emptying in diabetes. II. Treatment].

The application of novel investigative techniques has contributed to an increased understanding of the prevalence, pathophysiology and treatment of disordered gastric motility in diabetes. Gastrokinetic drugs have improved therapeutic options for symptomatic patients with gastroparesis considerably. Future approaches to modulate gastric and small intestinal sensory responses may lead to significant advances in treatment.

Cisapride↗
PubMed1994

The propeller flap: a one-stage procedure for nipple-areola reconstruction.

The advantages of the propeller flap combined with tattooing for nipple-areola reconstruction include the fact that it is a simple one-stage procedure, a secondary procedure after creation of the nipple-areola complex is eliminated, and a skin graft and the possibility of a skin graft and second wound are eliminated. The propeller flap technique offers the ability to produce a nipple of adequate size, good color match, and satisfactory projection over an 18-month follow-up. The preliminary results of this flap operation are promising. A long-term evaluation of this operation has begun.

Female↗
PubMed1991

[Evaluation of organochlorine pesticides in prepared daily food rations of employed and unemployed workers].

Determination was made of the contamination degree of the daily food rations illustrating the overall mean food intake per head in households of manual workers and in other households. The residues of DDT and of its metabolites as well as of alpha, gamma and beta isomers of HCH were determined. The results indicate that the contamination degree of the different food rations depended on the locality where the ration was prepared, on the kind of ration and kind of organochlorine pesticides. Food rations of manual workers' families, as compared with other families, were more contaminated with organochlorine pesticides their metabolites. The degree of contamination with DDT, DDE and DDD, as compared with HCH isomers, was from several to 10-20 times higher (manual workers' rations). DDT (concentration range between 2.95-124 micrograms/CRP) and gamma-isomer of HCH (concentration range between 0.512-3.0 micrograms/CRP) were dominant. Evaluation, according to ADI, of the yearly uptake of DDT and HCH with food indicates that the contamination degree of food rations (both--rations reproduced on the basis of reports of the Chief Census Bureau, and representative rations characterizing the degree of exposure of the Wielkopolska population to organochlorine derivatives) creates no health hazard to humans, and remains below the admissible concentrations.

Employment↗
PubMed1989

Esophageal blood flow in the rabbit: response to calcium channel blockers.

Calcium channel blockers have recently been added to the therapeutic regimen for patients who have chest pain of esophageal origin. Although relief of symptoms has been reported, this has not always been associated with changes in esophageal contraction pressures or luminal pH. Myoischemia has been proposed as one possible mechanism for esophageal chest pain. We have investigated the effect of the calcium channel blockers verapamil, nifedipine, and diltiazem on esophageal blood flow in the rabbit model. Esophageal blood flow was measured three times in each rabbit with use of the radiolabeled microsphere technique after a 30-minute continuous infusion of (1) saline solution (baseline), (2) a low dose, and (3) a high dose of each agent. Esophageal mucosal blood flow significantly decreased with nifedipine but was unchanged with verapamil and diltiazem. Esophageal muscle blood flow significantly increased--approximately 100% after administration of each of the calcium channel blockers. Thus esophageal muscle blood flow is enhanced after administration of calcium channel blockers, and this may be one therapeutic mechanism of the calcium channel blockers in the relief of esophageal chest pain in some esophageal diseases.

Animals↗
PubMed1988

Effects of prostaglandins on esophageal blood flow.

The physiologic mediators of blood flow to the esophagus are poorly understood. We have investigated the effects of prostaglandins on esophageal blood flow as they are known to alter blood flow in other organs of the gastrointestinal tract. Esophageal mucosal and muscularis blood flow (Q) were measured in New Zealand white rabbits treated intravenously with the prostaglandin analogs misoprostol (PGE1), 16,16-dmPGE2 (PGE2), and iloprost (PGI2, prostacyclin). Esophageal blood flow was measured three times in each rabbit using the radiolabeled microsphere technique after a 30-min continuous infusion of (1) saline (baseline), (2) a low dose, and (3) a high dose of each agent. Iloprost significantly increased esophageal mucosal (fourfold) and muscularis (twofold) blood flow. The other two PG analogs, misoprostol and 16,16-dmPGE2, had no significant effect on esophageal blood flow. Iloprost also significantly increased blood flow to the other organs of the gastrointestinal tract; however, the response was not as dramatic as in the esophageal mucosa. Prostacyclin may have a physiologic role in blood flow regulation to the esophagus and may be involved in pathophysiologic processes in the esophagus, such as increasing mucosal blood flow in response to injury.

16,16-Dimethylprostaglandin E2↗