Experimental autologous substitute vascular graft for transplantation surgery

Vascular complications in liver transplantation are a major cause of graft failure and mortality. The aim of the study was to create autologous vascular graft without risk of rejection. Posterior rectus fascia sheath lined with peritoneum was used for iliac artery replacement in seven mongrel dogs. The patency was followed by palpation and Doppler ultrasound. The grafts were removed after one month. Five grafts remained patent. The Doppler showed good, relatively increased flow (median flow rate: 383 cm/sec) after one month in all of the cases. Slight increase in diameter was present in all cases. By microscopy the five patent grafts showed viable morphology, fibroblasts, smooth muscle cells and thin fibrin layer in the wall. The grafts were lined partially with a neoendothelial monolayer and a thin fibrin layer. In conclusion, this graft presents an acceptable patency rate and low thrombogenicity, and could be useful in transplantation. Further investigations are needed to study the effect of immunosuppression and rejection on long-term morphology and patency of the grafts.     

Experimental transplantation of the patella in dogs

An experimental study of homogenous transplantation of bone with an articular surface was conducted by transplanting the patellae of six–terrier–sized dogs. Following surgery, clinical and radiographic observations were made on the transplanted bones over a period of 2 years. Three dogs were kept for 1 year, and the others for 1 5 , 18 and 24 months. The transplanted bones were examined histologically when recovered at autopsy The results demonstrated complete revascularization and remodelling of the transplant, without serious anatomical deformity, and limb function remained normal. Despite the satisfactory survival of the bone and cartilage elements of the graft, the articular surface became covered with connective tissue. The problems associated with the transplantation of whole or large sections of joints are discussed in the light of the study's findings. Résumé. On a procédé à une étude expérimentale de greffes osseuses homogènes avec une surface articulaire en transplantant les rotules de six chiens de la taille d'un terrier. Après chirurgie, on a fait des observations cliniques et radiographiques sur les os greffés au cours d'une période de 2 ans. On a gardé trois cheins pendant un an et les autres pendant 15, 18 et 24 mois. Les os greffés ont été soumis à un examen histologique quand on les a recouvrés à l'autopsie. Les résultats ont démontré une révascularisation et un remodelage complets de la greffe, sans sérieuses difformités anatomiques, et un fonctionnement normal des membres. Malgré la survivance satisfaisante des éléments de l'os et du cartilage de la greffe, la surface articulaire se couvrit de tissus connectifs. À la mise au jour des constatations de l'étude, on a discuté des problèmes associés avec la transplantation d'entières ou de larges sections d'articulations. Zusammenfassung. Eine experimentelle Studie von gleichartigen Transplantationen von Knochen mit einer gelenkigen Flǎche wurde ausgenùhrt, indem man die Patellae von sechs Terrier-grossen Hunde verpflanzte. Nach der Chirurgie wurden klinische und radiographische Beobachtungen von den verpflanzten Knochen ùber eine Période von zwei Jahren gehalten. Drei Hunde behielt man fur ein Jahr und die anderen fur 15, 18 und 24 Monate. Die verpflanzten Knochen wurden nach dem Tod histologisch untersucht. Die Ergebnisse bewiesen vollstàndige Ravaskularisierung und Umbildung des Knochentrans-plantats ohne ernsthafte anatomische Difformitùt, und Gliedfunktion war normal. Trotz des zufriedenstellenden Fortlebens des Knochen- und Knorpelelements in der Gewebeverpflanzung, wurde die gelankige Flàche mit Bindegewebe iiberdeckt. Die Problème, die mit dem Transplantǎt von ganzen oder grossen Teilen von Gelenken verbunden sind, werden im Licht der Befunde diskutiert.     

Microvascular transplantation of a free omental graft to the distal extremity in dogs

OBJECTIVE: To assess the survival of a free omental graft applied to an experimentally created wound on the distal extremity in dogs. STUDY DESIGN: A free omental graft was evaluated as a primary method of treatment for dogs with distal extremity wounds in an experimental model. ANIMALS OR SAMPLE POPULATION: Five adult intact female mixed breed dogs weighing 21.8 kg to 25.0 kg. METHODS: A free omental graft was harvested from the abdomen and transferred to a wound bed overlying the medial aspect of the tibia. A microvascular anastomosis was performed between the graft vessels and vessels at the recipient site. Daily clinical assessment of graft viability was performed. Angiography and 99mTechnetium labeled macroaggregated albumin (99mTc MAA) scintigraphic perfusion scans were performed on either day 4, 5, or 7. Postmortem collection of tissues for histopathologic analysis was performed immediately after imaging. Total operative time and graft ischemia time were evaluated for effects on graft survival. RESULTS: Two of seven grafts survived to the end of the study, three of seven grafts failed because of ischemia, and two of seven grafts failed because of self-trauma. There was no clinically significant morbidity associated with the abdominal portion of the procedure. Because of the small number of surviving grafts, the effects of operative time and graft ischemia time could not be statistically evaluated. CONCLUSIONS: Microvascular transplantation of a free omental graft can result in a viable tissue covering of a distal extremity wound, however, the failure rate is unacceptably high. CLINICAL RELEVANCE: A free omental graft may not have sufficient durability to be an acceptable wound covering by itself. Further studies combining omentum with a skin graft or other tissues may result in a clinically useful technique.     

Experimental cranial cruciate replacement in cattle using a patellar ligament graft

The cranial cruciate ligament was surgically removed from the right stifle joint in ten heavy steers and two bulls, and replaced with a tendon-ligament graft harvested from the tendon of the gluteobiceps muscle including a portion of the lateral patellar ligament. Two surgical techniques (placing the graft through a femoral bone tunnel and placing the graft through the joint space) were compared using six animals in each group.

Both surgical techniques were easily performed and caused minimal postoperative inflammation. The clinical response observed over four to five months was considered satisfactory in 9 of 12 animals. However, the tensile strength of the graft determined at necropsy was less than the cranial cruciate ligament in the opposite normal stifle in all animals tested.

     

Acute vascular and interstitial rejection following renal allograft transplantation in dogs

Renal allograft transplantation was performed in four beagles. Immunosuppressive treatment using cyclosporine, mizoribin and prednisolone was continued from Day 5 pre- until Day 20 post-transplantation. Between Days 28 and 32 post-transplantation, an abrupt elevation of the serum creatinine values followed by the development of uremia was seen in all recipients. Histopathology of the allografts examined between Days 28 and 37 revealed edema, necrosis, hemorrhage and severe diffuse interstitial cellular infiltration as well as tubulitis. Glomerular changes notably included swelling of the tufts due to hypercellularity, which was consistent with transplant glomerulitis. The intrarenal arteries exhibited fibrinoid necrosis of the walls and intimal or transmural cellular infiltration. These renal lesions were consistent with those of acute vascular and interstitial rejection in humans.     

Experimental results and clinical impact of using autologous rectus fascia sheath for vascular replacement

Vascular complications are major causes of graft failure in liver transplantation. The use of different vascular grafts is common but the results are controversial. The aim of this study was to create an 'ideal' arterial interponate for vascular replacements in the clinical field. An autologous, tubular graft prepared from the posterior rectus fascia sheath was used for iliac artery replacement in dogs for 1, 3, 6 and 12 months. Forty-one grafts were implanted and immunosuppression was used in separate groups. The patency rate was followed by Doppler ultrasound. Thirty-seven grafts remained patent, 2 cases with thrombosis and 2 cases with stenosis occurred. There was no evidence of necrosis or aneurysmatic formation. The histological analysis included conventional light microscopic and immunohistochemical examinations for CD34 and factor VIII. The explanted grafts showed signs of arterialisation, appearance of elastin fibres, and smooth muscle cells after 6 months. Electron microscopy showed intact mitochondrial structures without signs of hypoxia. In conclusion, the autologous graft presents acceptable long-term patency rate. It is easy to handle and the concept of beneficial presence of the anti-clot mesothelium until endothelialisation seems to work. The first clinical use was already reported by our group with more than 2 years survival.     

Experimental study of materials for patch graft on right ventricular outflow tract under extracorporeal circulation in dogs--comparison between Denacol EX-313-treated bovine jugular vein graft and expanded polytetrafluoroethylene (EPTFE) graft

A comparison between a bovine jugular vein treated with a hydrophilic polyepoxy compound cross-linker (Denacol), and expanded polytetrafluoroethylene (EPTFE), an artificial material, as a patch graft for the reconstruction of the right ventricular outflow tract under extracorporeal circulation in dogs, as if they had pulmonic stenosis, was made. Hemodynamic and histological examinations were conducted two weeks after the transplantation. Hemodynamic problems were not observed in either the Denacol or EPTFE groups. Macroscopically, organization of new tissue on the graft surface was more marked in the EPTFE group than in the Denacol group, and newly-formed tissue was seen surrounding the border of the graft and burying it in the EPTFE group. In the Denacol group, microscopic findings revealed the presence of inflammatory cells and fibroblasts, and an invasion of the graft by collagen fibers and elastic fibers. In the EPTFE group, there was minimal cellular infiltration of the graft and a thick layer consisting of collagen fibers and fibroblasts was observed around the graft. These results indicated that two weeks after transplantation the graft was better assimilated and organized with blood vasculature in the patch graft in the Denacol group than in the EPTFE group.     

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Relevance of the positron emission tomography in the diagnosis of vascular graft infection with Coxiella burnetii

Coxiella burnetii, the causative agent of Q fever, may cause culture-negative vascular graft infections that can be diagnosed by serology and molecular biology. We present a case of vascular graft infection detected by positron emission tomography (PET) scanner. The presence of C. burnetii was confirmed by high antibody titers and positive polymerase chain reaction specific for C. burnetii. This report emphasizes the relevance of the PET scanner in the diagnosis of infection when used in association with Q fever serology and molecular biology for the etiological identification of C. burnetii.     

Experimental transplantation models of mouse sarcoma 180 in ICR mice for evaluation of anti-tumor drugs.

Two new experimental models of transplantable mouse sarcoma 180 were developed in ICR mice in order to examine the optimum transplantation sites and methods. The cervicodorsal hypoderm was evaluated as the best transplantation site for mouse sarcoma 180 among seemingly usable transplantation sites such as groin, armpit, cervicodorsal, abdominal and lumbodorsal hypoderms by hypodermic transplantation. In addition, the lung transplantation model was established by monitoring the survival period as a reliable parameter for evaluation of anti-tumor effects.     

Experimental infection of cats with the liver fluke Platynosomum concinnum,.

The severity of Platynosomum concinnum infection in cats experimentally infected with 125 flukes (small dose) and 1,000 flukes (large dose) was determined by monitoring clinical signs and hematologic, serum biochemical, and pathologic changes during the infection. All cats (8/8) with a small fluke burden and 3 of 8 cats with a large burden remained clinically asymptomatic, whereas 60% of the cats given large doses had mild signs of inappetence and lethargy. Eosinophilia, peaking 4 to 5 months after infection, was present in all parasitized cats. During the early stages of platynosomiasis, a transient but substantial increase in aspartate aminotransferase and alanine aminotransferase activities was observed in cats given small and large doses. These observations agreed with gross and histopathologic observations, which included enlargement of the gallbladder and biliary ducts, with leukocyte infiltration, adenomatous hyperplasia, and fibrosis of the ductal areas.     

Experimental reconstruction of teat mucosa by vestibular mucosal graft in cows. A histopathologic and radiographic study

Injuries to the teat in dairy cows can result in partial or complete obstruction of the teat lumen. Different treatment techniques have been used to restore normal function in injured teats, one of which is autogenous mucosal grafts. The purpose of this study was to evaluate the vestibular mucosa as a replacement for teat mucosa in severe teat injuries. Sixteen teats of four healthy, mature, non-gravid Jersey cows were randomly divided into two equal groups. Under high epidural analgesia and after surgical preparation a 1 x 1.5 cm piece of teat mucosa was removed. In group 1, the defect was replaced by a 2 x 2.5 cm vestibular mucosa, whereas in group 2, the defect was left open. In both groups, a sterile disposable teat cannula was inserted into the teat cistern following surgery. To evaluate luminal diameter, double contrast radiography with constant air pressure was performed every 25 days till day 125, after which the animals were slaughtered and teats removed for histopathological study (H&E staining). On the basis of radiographic examination, luminal narrowing in group 2 was significantly more severe than in group 1. Histopathologically, the entire mucosal grafts of group 1 were taken and a good adhesion could be seen between the graft and the host epithelium. In group 2, severe submucosal fibrosis and mucosal papilloid hyperplasia resulted in severe narrowing of the teat cistern. According to the results of this study, it can be concluded that using vestibular mucosal grafts with temporary insertion of teat cannula can be considered as a method of treating teat mucosal injuries.     

Experimental systems which modify and simulate rapeseed-induced liver haemorrhages in in-lay hens

The occurrence of liver haemorrhages was compared when diets containing 30 or 40 per cent rapeseed meal (RSM) or 30 per cent soybean meal (SBM), with and without experimental additives, were fed to in-lay hens of a commercial egg-producing strain for 12 weeks. The incidence of haemorrhages was significantly greater when the birds were maintained on the basal (unsupplemented) RSM diet than on the equivalent SBM diet. Haemorrhages were either small and infrequent, minute and multiple as in peliosis hepatis, or large enough to rupture the liver capsule. They might be recent or old and encapsulated, sometimes both varieties affecting the same specimen, and they occurred in any part of the liver. Histologically, hepatocyte necrosis and reticulin derangement were not detected in livers without gross haemorrhages and even in those with haemorrhages these abnormalities were only seen closely adjacent to haemorrhages or to foci of eosinophilic fibrinoid. In some instances there was sinusoidal ectasia. Separate additions of 50 g dried skimmed milk powder, 0.5 g zinc oxide, 0.25 g ferrous sulphate or 2.0 mg selenium (as sodium selenite) kg-1 to the basal RSM diet did not significantly modify the incidence of haemorrhage. Ferrous sulphate slightly reduced goitrogenicity. Supplements of 2.2 mg menadione and 1.0 g sodium phenobarbital kg-1 RSM diet induced slight reductions in the number of cases of liver haemorrhage or their severity, indicating that the multifunction oxidase system may be involved in rapeseed hepatotoxicity. The addition of 0.5 g methimazole kg-1 to the basal SBM diet induced severe colloid goitre but did not induce liver haemorrhage. Both thiouracil (0.5 g kg-1 diet) and beta-aminopropionitrile (0.5 g and 2.5 g kg-1 diet) when added to the basal SBM diet induced liver haemorrhages which did not differ in incidence or histological appearance from those induced by RSM. Hyperplastic goitre was caused by thiouracil. Intrahepatic cholestasis induced by sodium taurolithocholate, bilirubin and alpha-naphthylisothiocyanate and extrahepatic cholestasis induced by bile duct ligation resulted in hepatocyte necrosis but not gross liver haemorrhages. Spontaneous deaths due to conditions other than liver haemorrhages were significantly more numerous in RSM-fed than SBM-fed hens.(ABSTRACT TRUNCATED AT 400 WORDS)     

Long-term complete chimerism and stable hematopoiesis in beagles after fetal liver hematopoietic stem cell transplantation

Karyotype analysis of bone marrow cells was performed from 6 Beagles that had received sex-mismatched fetal liver hematopoietic stem cell grafts 2.4 to 6.5 years earlier. Two dogs received dog leukocyte antigen-matched fetal liver cells and 4 received dog leukocyte antigen-mismatched cells. In each dog, all 25 evaluated metaphase spreads were of donor genotype. All dogs had normal hemograms and repopulation of bone marrow and no dog developed graft-vs-host disease.     

Biomechanical comparison of cortical radial graft versus ulnar transposition graft limb-sparing techniques for the distal radial site in dogs

OBJECTIVE: To compare the biomechanical properties of radial graft (RG) versus ulnar transposition graft (UTG) limb-sparing techniques in the dog. STUDY DESIGN: Cadaveric study. ANIMALS: Six pairs of normal canine thoracic limbs. METHODS: In each pair of limbs, 1 limb was subjected to the RG technique and the other to the UTG technique. Limbs were tested in axial loading until failure. Modes of failure and biomechanical properties were compared between the 2 groups. Percent coverage of the metacarpal bone by the plate was retrospectively compared between the limbs that failed by fracture of the metacarpal bones and those that did not. RESULTS: RG limbs had significantly greater stiffness, yield load, maximum load, maximum energy, and post-yield energy. All UTG limbs failed by cranial bending of the plate. Half of the RG limbs failed by caudal bending of the plate and half by fracture of the third metacarpal bone at the distal end of the plate. Limbs with <80% plate coverage of the metacarpal bone were significantly more likely to fail by metacarpal fracture. CONCLUSIONS: The RG technique was biomechanically superior to the UTG technique under the conditions studied. At least 80% plate coverage of the metacarpal bone should be achieved. CLINICAL RELEVANCE: Exercise restriction and coaptation bandages should be considered for patients undergoing the UTG technique to minimize potential biomechanical complications.