Experimental study of tracheal allotransplantation with cryopreserved grafts

OBJECTIVE: Tracheal reconstruction is necessary in patients with extensive tracheal stenosis caused by neoplasm, trauma, and congenital disease. We investigated the possibility of tracheal allotransplantation with cryopreserved grafts in a canine model. METHODS: A seven-ring section of thoracic trachea was removed in 19 adult mongrel dogs. In group A (n = 4), a five-ring tracheal autograft was implanted. In group B (n = 6), a five-ring allograft was implanted without immunosuppression. In group C (n = 9), a five-ring cryopreserved tracheal allograft was implanted without immunosuppression. Omentopexy wrapping around the grafts and both anastomotic sites was used in all animals. RESULTS: All grafts survived without any evidence of atrophy or stenosis in group A. All animals in group B died of severe airway obstruction within 1 month, and postmortem examination of these grafts showed epithelial defect and necrotic tracheal cartilage in the scar tissue. In group C, no animals died of asphyxia caused by severe stenosis of the grafts. The graft epithelium was no longer present 20 days after transplantation, and the graft was covered with regenerated epithelium within about 60 days after the operation. CONCLUSION: These findings show that cryopreserved tracheal allografts can be transplanted by means of omentopexy without immunosuppression and that cryopreservation may reduce tracheal allogenicity.     

Porous-type tracheal prosthesis sealed with collagen sponge

BACKGROUND: Reconstruction of a long section of the trachea is clinically problematic. Tracheal reconstructions using prostheses have met with limited success due to local infection, hemorrhage, luminal stenosis and prosthesis dislocation. METHODS: We have designed a porous type of tracheal prosthesis in which the mesh is sealed with collagen sponge. We used this prosthesis (50 mm in length) to reconstruct the cervical trachea in 10 mongrel dogs and evaluated its efficacy. RESULTS: One dog died due to an accident with anesthesia at 6 weeks and 1 of suffocation at 10 weeks. The other 8 dogs had an uneventful postoperative course until they were killed between 6 and 24 months after implantation. At sacrifice, all the prostheses had become completely incorporated into the host. Microscopic examination revealed advanced formation of a new epithelial lining in 1 dog at 6 months, and a confluent epithelial lining was observed in another dog at 12 months. Central stenosis was not significant in any of the animals. CONCLUSIONS: This tracheal prosthesis gives good results in canine tracheal reconstruction, and appears very promising for the clinical repair of tracheal defects.     

Experimental study of tracheal patch reconstruction with a covered expandable metallic stent

BACKGROUND: We evaluated the efficacy of tracheal patch reconstruction with a covered expandable metallic stent (EMS) with omentoplasty. METHODS: After resecting the right half of the circumferential wall of two tracheal rings in adult beagle dogs, we inserted a covered EMS to reconstruct the defect interiorly. Then, through laparotomy, we made an omental pedicle flap and wrapped it around the EMS-interposed area. For comparison with the group without omentoplasty, we periodically examined the healing process macroscopically and histologically. RESULTS: Bronchofiberscopic observations revealed that incorporation of the covered EMS progressed with the passage of time and tracheal luminal patency was maintained well in both groups. However, polyplike granulation developed gradually at both ends of the EMS. Histologically, epithelium was regenerated in the patched area 4 weeks postoperatively and the area was covered with pseudostratified ciliated epithelium at 12 weeks postoperatively. Quantitative analysis of the macroscopic and histologic findings showed that the inflammatory polyps were reduced and epithelialization was promoted in the group with omentoplasty. CONCLUSIONS: Tracheal patch reconstruction with a covered EMS, when combined with omentoplasty, promoted early epithelial regeneration and suppressed the development of inflammatory polyps.     

Variability of ciliary ultrastructure in normal dogs

The incidence of abnormal tracheal cilia from each of seven normal healthy dogs was estimated using samples prepared for TEM and SEM from the dorsal, lateral, and ventral aspects of the 3rd, 12th, and 24th tracheal rings. Some samples were demembranated with Triton X-100 and stained with tannic acid to visualize microtubular protofilaments. From each region of each ring of each dog on which TEM was done, 500 transversely sectioned cilia were observed, 27,000 cilia overall. Abnormal numbers of central microtubules and abnormal numbers of peripheral microtubules occurred in all samples in about 2% of all cilia. Compound cilia were consistently observed in samples from the 3rd ring and were not observed in any samples from the 24th ring. Therefore, before abnormal ciliary ultrastructure may be associated with disease, the rate of occurrence must exceed that in appropriate control individuals. Additionally, compound cilia, which have previously been associated with a variety of diseases, obviously occur in normal individuals; however, their observation may be a function of biopsy site selection.     

Habituation of facial muscle responses to repeated food stimuli

The AVE Micro Stent (AVE Inc., Santa Rosa, CA) is composed of helically welded 3 mm long, zigzag crowns with stent lengths from 6 to 39 mm and diameters from 2.5 to 4.5 mm. Quantitative coronary angiography and histologic analyses of acute and chronic implantation were obtained in 52 stented coronary segments of 18 dogs. Three hearts with 8 stented coronary segments were harvested after 24 hr, 3 hearts with 9 stented segments were harvested after 2 weeks, 6 hearts with 15 stented segments were harvested at 8 weeks, and 6 hearts with 20 stented segments were harvested at 24 weeks post-deployment. There were no procedural complications, deaths, or acute vessel closures. The average lumen diameter of the stented segment was largest at 2 weeks (3.3 +/- 0.3 mm). The smallest average diameters were observed at 8 weeks after the stent deployment (2.7 +/- 0.4, P < 0.05) with an increase again at 24 weeks (2.9 +/- 0.6). The pre-explant percent of stenosis was <30% in all animals. Histologically, a peak of inflammation was visible at 2 weeks; however, the extent of luminal narrowing reached its peak at 8 weeks and the lumen dimension increased somewhat at 24 weeks. The degree of intimal thickening remained relatively constant throughout the different time points (<200 microm). Overall, these data suggest that constrictive remodeling within the stented segment occurs at 8 weeks in this animal model. The later increase of the stented segment dimensions as well as higher net gain at 24 weeks compared to 8 weeks after deployment suggests that this constriction is a transitory phenomenon.     

Experimental pyeloureterectomy and calyceal neck transection with autotransplantation and bladder advancement

OBJECTIVE: To determine whether Dexon mesh, closely applied to the kidney, provides purchase for sutures to permit bladder/parenchymal apposition on autotransplantation and that, if this line of apposition were some distance from but surrounding renal papillae, urothelium would proliferate to cover exposed parenchyma to form a widely patent lumen; this should facilitate removal of the whole of an upper tract collecting system, retaining renal parenchyma alone. MATERIALS AND METHODS: To test this possibility and explore the practicability of the concept, nine dogs underwent bilateral nephrectomy followed by unilateral autotransplantation: the other kidney was discarded. Because the canine renal pelvis is intrarenal, the ureter was stretched maximally before passing fine scissors into the renal hilum to transect the collecting system as close to the kidney as possible in six of the nine dogs. In the remaining three dogs, partial nephrectomy was performed with division of the calyceal necks under vision. Thinned bladder wall was sutured to Dexon mesh some distance from the collecting tubules; omentum was applied to the suture line. RESULTS: Three dogs were killed prematurely at < 2 weeks because of perioperative complications. Four were killed at 2, 4, 5 and 8 weeks and two at 12 months. Dexon mesh proved to be an effective anchoring fabric, providing close apposition of bladder wall and parenchyma. There was no adhesion of the kidney to peritoneal contents. Urothelial proliferation to cover exposed parenchyma occurred early and by 12 months, a thin stroma was interposed between parenchyma and epithelium. The kidney was preserved in all but one removed electively, this dog having both cystitis and pyelonephritis at 12 months. CONCLUSIONS: This study showed that autotransplantation of a kidney after removal of its collecting system and advancement of thinned bladder wall to renal parenchyma is practicable, with regenerated urothelium bridging the deficiency by covering exposed parenchyma, to create a widely patent lumen.     

Restoration of sexual behavior and dopaminergic neurotransmission by long term exogenous testosterone replacement in aged male rats

PURPOSE: We investigated the effects of long-term testosterone replacement on copulatory behavior and dopaminergic neurotransmission in the medial preoptic area of aged male rats. MATERIALS AND METHODS: The rats were divided into 3 groups depending on testosterone replacement. Those in the long-term replacement group were castrated at the age of 12 months and received testosterone replacement thereafter for 12 months. In the short-term replacement group, rats were castrated at the age of 22 months and high or low dose testosterone replacement was done for 2 months. The control group consisted of aged rats 24 months old and young rats 12 weeks old, neither of which had been castrated or received testosterone replacement. We observed sexual behavior in rats of these groups. After a behavioral test, we measured the tissue concentration of dopamine in the MPOA and the change rate of the extracellular dopamine level induced by infusion of N-methyl-D-aspartic acid (NMDA) in the MPOA and compared the long-term replacement and no-replacement groups. RESULTS: The rats in the long-term replacement group showed a mount rate at the same level as that of young rats at 6 weeks after starting replacement and it was maintained to 24 months of age. Their mount rate was significantly higher than that of the rats with the short-term replacement. A significantly higher change rate of dopamine release was recognized in the long-term group; however, no significant difference in the concentration of dopamine was recognized between aged rats with long-term replacement and those without replacement. CONCLUSIONS: Aged rats (24 months old) with long-term testosterone replacement maintained almost the same level of mount behavior as young rats (12 weeks old). The results imply that long-term testosterone replacement may favorably alter the decline in the process of sexual activity with aging. The restoration by testosterone replacement of dopaminergic activity in the MPOA may be involved in the maintenance of sexual function in aged rats.     

Effect of age on serum concentrations of the third component of complement in dogs

Single radial immunodiffusion was used to determine the concentration of the third component of complement (C3) in canine sera from 48 normal dogs in the following age groups: < 12 months, 12 to 24 months, and > 24 months. Mean serum C3 concentrations, expressed as the percentage of pooled reference sera from 20 dogs, showed a significant (P < 0.017) correlation with age in dogs less than 12 months old, while the character of this correlation was negative for dogs more than 24 months old (P < 0.056). Two-way analysis of variance, for age and sex, revealed significant differences between C3 values from this two groups that were not present when compared with dogs aged between 12 and 24 months old. Sex had no effect on serum C3 concentrations.     

Improved airway healing using basic fibroblast growth factor in a canine tracheal autotransplantation model

OBJECTIVE: We studied 22 dogs to examine the effect of basic fibroblast growth factor (bFGF) alone, in comparison with omental or muscular wrapping on airway healing in a tracheal autotransplantation model. SUMMARY BACKGROUND DATA: Basic fibroblast growth factor is one of the most potent promoters of angiogenesis and has an ability to enhance blood supply to the ischemic airway. Topical administration of a fibrin glue enriched with 5 microg/cm2 bFGF, determined as a proportion of surface area of the tracheal grafts, improved revascularization of orthotopic canine tracheal autografts in a previous study. METHODS: All animals received orthotopic tracheal transplantation using 6-ring autografts that occupied a distal part of the thoracic trachea. Twenty-two animals were classified randomly into the following four groups: no treatment (Group G1, n = 4), muscular wrapping (Group G2, n = 4), omental wrapping (Group G3, n = 4), and topical administration of fibrin glue enriched with 5 microg/cm2 bFGF (Group G4, n = 10). Autografts were harvested 60 days after transplantation and assessed by the percent patency and histology. RESULTS: Devascularized tracheal autografts could not maintain their structural integrity without other treatments (Group G1). In contrast, more than half of all autografts receiving treatments remained viable, as demonstrated by gross and histologic findings (Groups G2, G3, and G4). Treatments with bFGF and omentum showed significantly better graft viability than no treatment. However, there was no statistical difference in the viability of tracheal autografts among the three treatment groups. In terms of the time performance ratio, bFGF was the best treatment for the devascularized autografts. CONCLUSIONS: Topical administration of bFGF was superior to the omental or muscular wrapping in terms of the time performance ratio. Clinical trials will be necessary to determine whether these findings are applicable to humans.     

Radiotherapy of exudative senile macular degeneration. A prospective controlled study

Despite the successful therapy of subretinal neovascular membranes by laserphotocoagulation there are many problems to be overcome. In the case of subfoveolar neovascularization, photocoagulation leads to a sudden decrease in visual acuity. Recently radiotherapy is considered as an alternative. Complications and effectivity were evaluated in this prospective and randomized trial. The initial results are presented. PATIENTS AND METHODS: There are 76 patients (51 women, 25 men, average age 77.7 +/- 8.6 years) included in the prospective randomized study. All of them show subfoveolar neovascular membranes in FLA and a decrease in visual acuity between 0.05 and 0.5. They were randomly assigned to either the radiotherapy or the control group. Radiotherapy was done within 6 days by 6 x 2 Gy (6 MV photons). The follow-up was at 4 weeks, after 3 months, after 6 months and then every 6 months after the end of radiotherapy. On average the follow-up is at 15.1 months. RESULTS: Concerning age and visual acuity before therapy, the control group and the radiotherapy group were not significantly different. At 4 weeks after radiotherapy, visual acuity was 0.13 +/- 0.46 (LogMAR). After 12 months, visual acuity at a distance was 0.11 +/- 0.30 in the therapy group and 0.09 +/- 0.13 (P = 0.838) in the control group. Patients with a preoperative visual acuity better than 0.2 improved more after radiotherapy. Metamorphopsy improved in 75% of the therapy group. The following complications could be observed: In the control group 3 patients suffered subretinal bleeding, in the radiotherapy group 3 patients, respectively. CONCLUSIONS: At present, the follow-up is too short to recommend radiotherapy as a standard procedure in the case of subfoveolar neovascularization. The results in patients with a better preoperative visual acuity encourage us to continue this study.     

Orbital mass in a child causing somnolence, nausea and bradycardia

Aorto-esophageal fistula due to ruptured thoracic aortic aneurysm is very rare but is associated with extremely high mortality. An 81-year-old woman was admitted due to repeated hematemesis. Endoscopic examination revealed ulceration with blood clot on the mid-esophagus and compression of an extra-esophageal mass. The thoracic CT scan revealed an aorto-esophageal fistula due to a ruptured descending thoracic aortic aneurysm. Surgery was performed on April 3, 1996. We report an aorto-esophageal fistula managed successfully in one stage by resection and replacement of the aortic aneurysm with a prosthetic graft and total esophageal resection. The esophagus was reconstructed using orthotopic gastric interposition with omentopexy around the prosthetic aortic graft. The postoperative course was uneventful and there have been no signs of mediastinal sepsis, graft infection or pyothorax 12 months postoperatively. We suggest that the resection of both the aneurysm and the esophagus as well as the immediate reconstruction of the esophagus by orthotopic gastric interposition to obliterate the retrosternal space are important technique in the management of intrathoracic infections.     

Comparison of primate and canine models for bone ingrowth experimentation, with reference to the effect of ovarian function on bone ingrowth potential

Bone growth into porous composite (mesh-bead) titanium plugs was compared in elderly (postmenopausal) female monkeys and female dogs as a means of validating the cross-species interpretations so often made between data from research on dogs and human applications. The effect of oophorectomy on bone ingrowth in the canine model was defined by the comparison of data on fractional ingrowth in animals that had had oophorectomy and in control animals that had had a sham operation. No significant difference in bone growth into the experimental plugs was identified between the two animal models, which lends credence to cross-species interpretation of existing data from dogs. The presence or absence of active ovaries did not affect the ingrowth fraction in the canine model; this suggests that existing data are not confounded by the lack of control of ovarian function. Estrogen depletion does not appear to influence bone ingrowth adversely.     

Effect of cisplatin chemotherapy on extracortical tissue formation in canine diaphyseal segmental replacement

The reconstruction of large bone and joint defects after the resection of malignant tumors remains a major challenge. Chemotherapy has significantly lowered the risk of metastasic disease, but complications associated with reconstructive techniques continue to result in late morbidity. In the present study, biomechanical torsion testing, gait analysis, and histomorphometric and scanning electron microscopic evaluations of 24 dogs were used to examine the effects of preoperative and postoperative administration of cisplatin on the biologic fixation of a porous-coated segmental replacement prosthesis. The chemotherapy consisted of four cycles of cisplatin administered at a dosage of 75 mg/m2 preoperatively or postoperatively. The healing was enhanced by use of an autogenous corticocancellous bone graft. The graft was placed evenly around the prosthesis and the adjacent femoral cortex. Mechanical analyses of torsional stiffness, yield strength, and maximum strength revealed no statistically significant differences between the groups at 12 weeks. Such lack of difference was mainly due to the penetration of highly organized fibrous tissue into the porous surface; this provided strong fixation of the implant to bone even in the absence of bone ingrowth. Although bone ingrowth into the prostheses was not affected, electron microscopic, histomorphometric, and radiologic analyses showed a clear difference in the formation of new bone around the prosthesis. Preoperative chemotherapy did not alter the formation of new bone, but specimens from animals treated postoperatively with cisplatin showed significantly less bone graft resorption and less new bone formation. Hence, the effect of cisplatin administration caused only a temporary delay, not a permanent effect, on extracortical capsule formation. The formation of extracortical bone and soft tissue might prevent debris-incised osteolysis and, therefore, prevent late complications by forming a tight capsule around the bone-prosthetic interface.     

Intraarticular hip treatment with triamcinolonehexacetonide in juvenile chronic arthritis

To evaluate the effect and tolerance of intraarticular Triamcinolonehexacetonide (TCH) in the course of chronic coxitis in juvenile chronic arthritis (JCA) in an open uncontrolled study. Since 1990 we treated patients < 16 years of age suffering from chronic coxitis with 1 mg/TCH/KG body weight. The patients were checked again 4-8 weeks after the treatment. Clinical and ultrasound courses were recorded with the help of ultrasound and joint scores. The evaluation took place 6, 12, 24 and 36 months after the treatment. At that time we give a report on the 12 months follow-up of 37 hip joints and the 24 months follow-up of 20 hip joints. The immediate effect of TCH influencing mobility, pain sensitivity and joint effusions of the patients is impressing. The long term effect of TCH has to be evaluated by regular check ups for at least 2 years. An individual comparison with the not treated contralateral joint would be desired if ethically justifiable. Most patients suffering from polyarticular diseases with a long course of coxitis needed more than one injection of TCH (mean reinjection time 5.8 months). Any avascular necrosis of the femoral heads or other complications were not observed.     

Clinical application of soft-tissue flap with an intercostal vascular pedicle from the chest wall in the trachea surgery

Between 1976 and 1995, 11 cases of side-wall defect repairment or circumferential reconstruction of trachea were performed using chest-wall tissue flap with an intercostal vascular pedicle. The indications were benign or malignant tumors of the tracheal side wall, lung cancers of the right upper lobe involving the side wall of the trachea and/or carina. The transverse diameter of the tracheal defect after removing the tumor was less than half of the tracheal circumference. Furthermore, we foun it feasible to reconstruct the trachea by using a tissue tube created by wrapping a chest-wall tissue flap over a temporary stent in case of long-segment tracheal resection of tracheal tumor or benign stenosis where. The defect was too long to be repaired by end-to-end anastomosis. The surgical technique & instructions were described.     

Histological and biomechanical analysis of bone and interface reactions around hydroxyapatite-coated intramedullary implants of different stiffness: a pilot study on the goat

We hypothesized that reduced stem stiffness of orthopaedic implants contributes to a high risk of loosening, since interface stresses and relative motions may exceed a tolerable range. To study this hypothesis, three types of load-bearing implant with different stiffnesses were inserted into the tibia of the goat. Histological analysis was performed of bone repair after insertion of the implant, bone ingrowth, interface disruption and loosening. A finite element model of the configuration provided the quantitative range of interface stresses and relative motions for the present experiment. The implants were made out of stainless steel, hollow titanium and a thin titanium core covered with a polyacetal coating. The stiffness ratios of these implants were approximately 10:4:1, respectively. All implants were coated with a layer of hydroxyapatite (HA) in order to minimize the possible biological effects of the different implant materials. Irrespective of the type of implant, there was a repair phase that lasted 6-12 weeks. The stiff implants functioned well. Large areas of bone bonding to the HA layer were found after the repair phase at 12 weeks postoperatively. After 24 weeks, some signs of loosening were observed. More loosening occurred with the hollow titanium and polyacetal implants, mainly during the repair phase. Three hollow titanium and three polyacetal coated implants survived this period, and were killed after 24 weeks. The integrity of the HA layer at the bone-implant interface of the titanium implants was good. In the polyacetal implants, the repair reaction of the cortical bone was incomplete. Bone ingrowth into HA was largely lacking. In conclusion, we found significant differences in the repair and interface reactions around implants of different stiffness. Stiff implants showed favourable initial interface conditions for bone ingrowth. Intermediate and flexible implants provoked unfavourable interface conditions for initial bone ingrowth. The finite element study showed that the flexible stems produce larger micromotions and higher interface stresses at the bone-prosthesis interface than the stiff stems, indicating an explanation for the histological findings.     

Morphologic aspects of experimental esophageal lye strictures. II. Effect of steroid hormones, bougienage, and induced lathyrism on acute lye burns

Among 77 dogs surviving standardized transmural esophageal lye injury for at least 2 weeks and as long as 12 weeks, 24 were untreated, 26 received corticosteroids and bougienage (S&B), and 27 received only the lathyrogen beta-aminoproprionitrile (BAPN). Stricture frequency was reduced markedly and significantly in the S&B and BAPN groups when compared to the controls (p less than 0,01). Strictures resulted from inward circumferential remodeling of all mural layers, not proliferating bulky scar tissue, and persistent ulceration was apparently not an influential factor in any group. The S&B dogs invariably showed reduction of the internal or mucosal length of the injured segment as compared to the outer length; these relations were quite variable in the other two groups so that mean internal shortening was significantly greater (p less than 0.01) in the S&B group. Marked mural thinning in the injured zone was present in all three groups but was most frequent in the BAPN-treated animals. The major conclusion is that BAPN-induced changes in the physical properties of reparative tissue can increase the ultimate caliber of an injured hollow viscus without resort to mechanical bougienage. In addition, the data suggest that wound contraction may play a role in stricture formation in this model.     

Evaluation of bovine-derived bone protein with a natural coral carrier as a bone-graft substitute in a canine segmental defect model

The efficacy of a bone-graft substitute (bovine-derived bone protein in a carrier of natural coral) in the healing of a segmental defect of a weight-bearing long bone was evaluated. Twenty dogs, divided into two groups, underwent bilateral radial osteotomies with creation of a 2.5 cm defect. On one side of each dog, the defect was filled with autogenous cancellous bone graft. Contralateral defects received, in a blinded randomized fashion, cylindrical implants consisting of natural coral (calcium carbonate) or calcium carbonate enhanced with a standard dose of bovine-derived bone protein (3.0 mg/implant; 0.68 mg bone protein/cm3). The limbs were stabilized with external fixators, and all animals underwent monthly radiographs. They were killed at 12 (group 1) or 24 (group 2) weeks, and regenerated bone was studied by biomechanical testing and histology. Radiographic union developed in all 20 radii with autogenous cancellous bone grafts and in all 10 of the radii with the composite implants. None of the radii with implants of calcium carbonate alone showed radiographic evidence of union. This represented a statistically significant difference between implant types. In addition, calcium carbonate implants both with and without bone protein demonstrated radiographic evidence of near total resorption of the radiodense carrier by 12 weeks. This resorption facilitated radiographic evaluation of healing. Mean values for biomechanical parameters of radii with the composite implants exceeded those for the contralateral controls at 12 and 24 weeks; the difference was statistically significant at 12 weeks. Histology revealed scant residual calcium carbonate carrier at either time in the defects with calcium carbonate implants; however, a moderate amount was present in defects with the composite implants. In these specimens, the residual carrier was completely surrounded by newly formed bone that may have insulated the calcium carbonate from further degradation. The present study used a carrier of granular calcium carbonate reconstituted with bovine type-I collagen to deliver an osteoinductive protein to the defect site. This carrier is of nonhuman origin (eliminating the risk of disease transmission or antigenicity) and resorbs rapidly. In this model, bovine-derived bone protein in a natural coral carrier performed consistently better than the gold standard autogenous cancellous bone graft in terms of the amount of bone formation and strength of the healed defect. This may have implications for removal of hardware or resumption of weight-bearing in certain clinical situations. These data also indicate that coralline calcium carbonate alone represents a poor option as a bone-graft substitute in this critical-sized segmental defect model.     

Allograft replacement of the trachea. Experimental synchronous revascularization of composite thyrotracheal transplant

We describe a method for experimental tracheal transplantation that uses synchronous revascularization based on the blood supply of the related thyroid gland. This study compares the structural integrity and histologic features of nonvascularized tracheal transplants, revascularized thyrotracheal composite allografts, with and without immunosuppression. Eighteen adult beagle dogs underwent tracheal transplant operations with one of the preceding methods. Postmortem specimens were studied macroscopically and histologically, 3 to 28 days postoperatively. Proximal, mid, and distal segments of each graft (twelve-ring segments) were examined microscopically. Nonvascularized tracheal transplants necrosed completely as early as 3 days postoperatively. The vascularized composite thyrotracheal allografts survived for up to 28 days. Six dogs did not receive immunosuppressive agents; tracheal cartilage was preserved in this group, but soft tissue necrosis developed. Six dogs received cyclosporine; tracheal cartilages and all soft tissues remained histologically intact. This difference may be due to early tracheal cartilage ischemia in the nonvascularized group, rejection of the soft tissues in the nonimmunosuppressed group, and viability of all structures in the vascularized and immunosuppressed group. Revascularization of the transplanted trachea with the thyroid arteries maintains the vascularity and hence the viability of the trachea. A reliable substitute for long-segment tracheal resections is finally found. We predict that clinical application of this technique will solve a major problem in the surgery of the airways.     

Aspects of the nutrition of adult female Glossina morsitans during pregnancy

The hepatic artery was embolized with Gelfoam in 12 dogs to evaluate the effect of embolization on hepatic function. Liver function studies, including SGPT, alkaline phosphatase, BSP test, and bilirubin, were done serially over a 6 week period following the embolization. Eleven of the 12 embolized dogs survived the 6 week experimental period. Hepatic artery embolization caused some liver damage; however, recovery occurred by 6 weeks. These results suggest a possible therapeutic role for hepatic artery embolization in patients with massive hepatic bleeding or hemobilia who are not surgical candidates and who would require hepatic lobectomy or dearterialization to control the bleeding.