[Local treatment of infection with collagen gentamicin].
Explore the source record for details and available documents.
Adult↗
Biomedical subjects
R Ascherl
Publications and source records attributed to R Ascherl.
[Immunization against blood group antigens by allogeneic bone transplantation].
33 bone allotransplants (cryopreserved) of AB0- and Rh-incompatible (donor-recipient) patients were performed to evaluate the question which AB0 Rh-incompatibility leads to immunization of the bone transplant recipient. Several different antibodies were tested pre- and postoperatively in the recipient. Regarding the Rh-system no immunization was demonstrable; however, a significant increase of antibody leads was found regarding the AB0-system. Thus, in bone bank techniques AB0 compatibility is important for allogeneic bone transplantation in young women. Otherwise, there is a risk for the development of MHN in case of pregnancy. Blood group-typing is not necessary in other patient groups. Although no Rh-antibodies were demonstrable, a similar mechanism can be postulated for the Rh-system. We, thus, conclude that in allogeneic bone tx in young women the Rh-system has to be taken into consideration.
ABO Blood-Group System↗
[Bone healing--an immunoreactive process?].
Cell mediated immune reactions, demonstrated by leukocyte migration assay and histological analysis of spleen and lymph nodes, could be observed after fresh autografting of cortical segments in rats. The detected immune answer showed a bone-specific reaction pattern. In consideration of the temporal correlation of the observed immune reactions and the histological signs of graft incorporation, a connection of bone healing and immune system may be possible.
Animals↗
[Orotracheal intubation in rats].
A detailed description of the technique of orotracheal intubation under visual control in rats is given. This method was used successfully in 190 animals, the complication rate being 3.2%. The hazards consisted of laryngospasm (1.6%) and fatal bleeding (0.5%). Intubation was proved to be a safe, reliable, simple and atraumatic way to establish a patent airway in this laboratory animal.
Animals↗
Non-linear three-dimensional finite element analysis of a cementless hip endoprosthesis.
In this finite element study the stresses between a stem component of a cementless hip endoprosthesis (Young modulus of Co-Cr-Mo) and the human femur were calculated for two different loading types. Linear and non-linear models were used to simulate the interface implant bone. Two models, a stem with a porous coated surface over the entire length and a stem with a porous coated surface in the proximal region were compared regarding the load transmission to the femur. An additional calculation of an 'isoelastic' stem (Young modulus of cortical bone) was done to show the influence of the stem stiffness. A porous coated surface over the entire length causes principal shear stresses up to 2.75 MPa in the distal-medial region during level walking. The highest compressive stresses were calculated in the proximal-lateral region as 1.5 MPa in cancellous bone. A more physiological load transmission is obtained by limiting the coated area to the proximal region. All stresses in the two models are lower than experimentally evaluated strengths in the interface between implant and bone. A strong influence of the Young modulus of the stem material on the interface stresses was found. An 'isoelastic' stem causes compressive stresses in the proximal-lateral region whose values exceed the experimental strength of cancellous bone.
Biomechanical Phenomena↗
[Material related aspects of surface structured endoprostheses].
In this article technical problems of surface-structured endoprostheses for cementless implantation are discussed. On the basis of four prostheses (two hip and two knee endoprostheses) various different porous coating technologies are compared. One sintered sphere layer, a cast sphere layer, a cast layer with "spongy-bone" structure and a plasma sprayed coating were compared. The quality of the bonding between the prosthesis and the porous surface layer was examined metallographically using polished specimens, with additional investigation of fraction surfaces of special tension test specimens. Additional information is given on the notch effect of the different coatings, in terms of a reduction in fatigue strength. The notch sensitivity differs for each material, and the reduction in fatigue strength is discussed for different implant alloys and different technologies for surface structuring. The investigation shows that the present quality of surface-structured endoprostheses is not satisfactory. We would like to thank the Dr. Johannes Heidenhain Foundation for financial support of this research.
Biomechanical Phenomena↗
Results after transplantation of canine pancreatic grafts with preserved exocrine drainage.
Explore the source record for details and available documents.
Anastomosis, Roux-en-Y↗
Laser induced shock wave lithotripsy--biologic effects of nanosecond pulses.
Laser energy of a Nd-YAG laser (1064 nm. wave length, 8 nsec pulse duration) was directed against various tissue cultures and the urothelium of the ureter, bladder and kidney parenchyma in pigs. Single pulse energy was 50 to 120 mJ with a repetition rate of 20 Hz. Urothelium and kidney parenchyma were irradiated in seven pigs. Tissue samples were examined histologically and electron microscopically directly, two, four, eight and 12 days after irradiation. No macroscopic lesion could be found. Maximum energy caused a small 'rupture cone' of 40 micron. depth. No thermic effects or necrosis resulted, so that no harm is to be expected with unintentional irradiation during laser stone disintegration.
Animals↗
An evaluation of retrieved UHMWPE hip joint cups.
In this study it is demonstrated that the combined chemical and mechanical influences of the implant situation cause property changes of ultra-high-molecular-weight polyethylene (UHMWPE) hip joint cups. Nearly 250 loosened hip cups, retrieved 3 weeks to 14 years after implantation, were investigated. The clinical long-term behavior of various shaped polyethylene hip sockets are statistically analyzed. The main damage features were defined and described. Density measurements show a density increase with implantation time and a dependence of these changes from implant position and loading conditions. The rate of extractable constituents also increases with course of time. An increased in vivo conditioned oxidation of the UHMWPE can be demonstrated by infrared (IR) spectrometry. The density increase can be explained by post-crystallization, which is the result of oxidative chain scission. This leads to a reduction of the average molecular weight of the PE and to an increased extractability of constituents. Since these changes have been recognized as the reasons for aging and failing of UHMWPE, the methods of material characterization used in this study for retrieved implants will help to develop suitable in vitro testing and simulating methods. Characteristic damage features of hip cups allow direct relationships with construction characteristics and their improvement.
Hip Prosthesis↗
Animal experiments on hemostasis with a collagen-fibrin tissue-adhesive sealant in the nephrostomy tract.
After a median laparatomy, nephrostomy was performed on 22 porcine kidneys: puncture, dilatation and introduction of a 26-French operating sheath through the parenchyma into the renal pelvis. At the end of the operation, an 8-French nephrostomy catheter prepared with a collagen-fibrin tissue-adhesive sealant was introduced through the operating sheath and the sheath was afterwards extracted. The hemostasis in the nephrostomy tract was very good in all 22 cases. There were no complications such as wound infection or stone formation during a post-operative period of between one and 95 days. Experimental investigations showed severe bleeding in nontamponade of the nephrostomy tract, in tamponade with an 8-French nephrostomy catheter and in tamponade of the nephrostomy tract with the collagen fleece wrapped around an 8-French nephrostomy catheter but not coated with the fibrin glue.
Animals↗
[Morphologic examination of the urothelium after irradiation with laser energy].
The energy of a Nd-YAG laser (1,064 nm wave length, 8 ns pulse duration) was used to irradiate the urothelium of the ureter or bladder and kidney parenchyma in pigs. Single pulse energy was 50-120 mJ with a 20-Hz repetition rate. The horizontal laser beam was reflected 90 degrees down by a 100% mirror and with a specially designed apparatus focussed on the surface of the tissue. Laser light from a quartz glass fiber was also focussed directly onto the tissue. Urothelium and kidney parenchyma were irradiated in 7 pigs. Tissue samples were examined histologically and raster electron microscopically 2, 4, 8 and 12 days after irradiation. No macroscopic lesion could be found. Maximum energy caused a small cone of 40 micron depth. No thermic effects or necrosis resulted, so that no harm is to be expected with unintentional irradiation.
Animals↗
Local hemostasis of nephrostomy tract with fibrin adhesive sealing in percutaneous nephrolithotomy.
In 26 patients percutaneous nephrolithotomy was carried out under local anesthesia with systemic sedation. Instead of the 25-French nephrostomy catheter used so far, a 5- or 10-French nephrostomy catheter prepared with a collagen-fibrin adhesive sealant was introduced into the nephrostomy tract. In all cases, excellent hemostasis was attained with the fibrin glue. In applying a fibrin glue, the danger of protracted venous or arterial hemorrhage from the parenchymal canal can be markedly reduced; the large-lumen nephrostomy catheter can also be dispensed with.
Aprotinin↗
Endocrine function of canine segmental pancreatic grafts in relation to venous drainage site and duct management.
Explore the source record for details and available documents.
Amylases↗
[The clinical administration of the opioid antagonist naloxone in dogs].
The short introduction gives a review on the complex of exogen and endogen opioids and their receptors as well as on their pharmacodynamics, pharmacokinetics and toxicity of naloxone. The clinical efficacy of naloxone as an opioid antagonist is described. Applications of naloxone for the dog are specified: antagonisation of etorphine, morphine, levomethadone and fentanyl, antagonisation of exogen and endogen opioids in puppies and treatment of lactomania in the bitch. The mean effective dose to antagonize morphines is 0.003 mg/kg bodyweight. If persisting analgesia is indicated the dose of naloxone in titrating steps in 0.001 mg/kg bw. To antagonize postpartal hypoxia in puppies 0.02 mg per animal naloxone have to be injected. For treatment of lactomania a dose of 0.01 mg/kg bodyweight twice a day for a couple of days is recommended. The clinical effectivity of naloxone is proved doubtlessly. Compatibility and safety are very high.
Animals↗
Experimental bioprosthetic reconstruction of the trachea.
We removed the tracheas from sacrificed laboratory animals and subjected this tissue to multi-step chemical processing. This method allowed us to preserve the cartilage and reduce its antigenicity, thus creating a bioprosthesis very similar to the host tissue. By using allogeneic and xenogeneic prostheses so prepared, no signs of immune rejections were seen following heterotopic or orthotopic implantations. The transplanted cartilage remained stable for periods ranging up to 21 weeks in recipient rats, while partial morphologic integrity of the cartilage was seen up to 1 year in pigs. Reepithelialization of the transplant with ciliated epithelium was completed in all specimens 12-24 weeks following surgery. Segmental replacement of up to one third of the whole trachea was possible in rats, whereas similar segmental replacements failed in pigs. We also found that successful reconstruction of window-shaped defects was possible. We consider our tracheal bioprosthesis to be superior to cialit-preserved grafts and also to most other biological reconstruction procedures.
Animals↗
[Treatment of chronic osteomyelitis with a collagen-antibiotic compound--preliminary report].
A compound of collagen and gentamicin was used in a controlled examination on 67 patients for the treatment of posttraumatic as well as postoperative osteomyelitis and, when applying cement-free endoprostheses, for hemostasis and local prevention of infection in the bed for implantation. Even in case of relatively high doses, the gentamicin concentration measured was only at the threshold value of detectability, due to the local application of the absorbable antibiotic compound. In most of all cases (n = 63), the healing of infection is demonstrated by clinical and radiobiological investigation.
Collagen↗
Definition of normothermic ischemia limits for kidney and pancreas grafts.
Normothermic ischemia tolerance is an important aspect of organ procurement and transplantation. The function of pancreas and kidney autografts was investigated in totally pancreatectomized or nephrectomized canine recipients. In 30 dogs the left limb (tail) of the pancreas was removed but left in the abdominal cavity after cessation of blood flow to produce warm ischemia for 30, 60, and 120 min (10 dogs at each time point), and then was flushed with cold Ringers' lactate and transplanted to the iliac vessels. Twenty dogs with fresh pancreatic transplants were controls. The success rate of pancreas transplants with warm ischemia of 1/2 and 1 hr was the same as that of controls (80%); however, after 1 hr normothermia 5/10 dogs had episodes of hyperglycemia for 1 week before glucose levels came back to normal. All but one graft with 2 hr warm ischemia failed. Intravenous glucose tolerance test (IVGTT) mean (+/- SEM) K values were not different in the successful groups, i.e., no warm ischemia: -1.55 +/- 0.15%; 1/2 hr warm ischemia: -1.81 +/- 0.18%; 1 hr warm ischemia: -1.64 +/- 0.09%. Amylase levels increased after transplant with maximum values at Day 2, then returned to normal, but the levels remained elevated in recipients of grafts subjected to longer normothermia with evidence of pancreatitis after 1 hr warm ischemia. Fifteen kidney grafts were treated similarly with warm ischemia exposure of 1/2 hr (n = 9) and 1 hr (n = 6) before being flushed and autotransplanted, and were compared to 16 fresh kidney transplants. After 1/2 hr warm ischemia none of the kidney grafts failed but 78% of the recipients had elevated serum creatinine and urea nitrogen levels which returned slowly to normal after 3 to 4 weeks. There was only one long-term survivor after 1 hr warm ischemia. Thus the pancreas seems to be more resistant to warm ischemia damage than is the kidney. This difference should be taken into consideration in regard to organ procurement for clinical transplantation.
Amylases↗
[Experimental studies and clinical aspects of cold-preserved allogenic spongiosa].
Different temperatures, freeze techniques, and durations of storage for cryopreservation of allogeneic spongious bone were studied in an experimental model. Low temperatures (-70 degrees C to 196 degrees C) without cryoprotectants proved to be favorable in micromorphological as well as scintigraphic analyses. These transplants seem to be equivalent to fresh autologous transplants - at least in animal experiments. Medium-term durations of storage (3 mo) at low temperatures yield the best osteoinductive capacity. Long term storage (12 months) and radiosterilization reduce the quality of the allogeneic bone. The clinical results in 495 transplantations of cryopreserved allogeneic spongious bone confirm the experimental findings.
Animals↗