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Biomedical subjects

C W Miller

Publications and source records attributed to C W Miller.

198 records · Page 11Linked to original sources
PubMedDate not supplied

Transfer of free vascular cutaneous flaps by microvascular anastomosis. Results in six dogs.

Skin defects on the distal extremities of six dogs were reconstructed with free vascular cutaneous transfers by microvascular anastomosis. The donor flaps were based on the superficial cervical artery and vein. In five of the dogs, bone was exposed and skin was lost from half of the circumference of the limb. Two had infected fractures with sequestra and three had acute shearing injuries. The sixth dog had sensory denervation of the left antebrachium and a carpal acral lick granuloma. Before surgery, the patency of potential recipient vessels was confirmed with arteriography in five dogs and an ultrasonic doppler in one dog. Microvascular technique was used to reestablish circulation to the flaps after they were transferred to the recipient site. Total ischemic time of the flaps averaged 100 minutes. All flaps survived. Successful reconstruction of the cutaneous defects was achieved in these six cases.

Anastomosis, Surgical↗
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Esophageal replacement in the dog by microvascular colon transfer.

An orthotopic colon graft based on the middle colic artery and vein was implanted with microvascular technique and a stapling instrument in five dogs. The grafts were successful in four dogs. A similar colon autograft was used to replace the entire thoracic esophagus in five dogs. The recipient vessels were the left carotid artery and left external jugular vein. Four of the grafts failed because of kinking and thrombosis of the arterial supply (2 dogs) or the venous outflow (2 dogs). One graft, which had a viable vascular supply, developed a severe leak at the colon-to-stomach anastomosis, and the dog was euthanatized on day 3. The recipient vascular pedicle was modified and used successfully to replace a portion of the cervical esophagus in three dogs. The grafts survived, the dogs could swallow liquids and semisolid food well, and, at necropsy after 4 weeks, the anastomotic sites were well healed. The graft sites contained essentially normal colon mucosa.

Anastomosis, Surgical↗
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Urinary incontinence after surgical repair of ureteral ectopia in dogs.

Eleven of 20 dogs (55%) were incontinent after surgical treatment of ureteral ectopia. Ureterocystostomy was performed in 15 dogs, ureteral transection and bladder reimplantation in four dogs, and ureteronephrectomy in one dog. Siberian huskies had a significantly higher rate of persistent postoperative incontinence than other breeds. There was no difference in postoperative incontinence between dogs with unilateral and bilateral ectopia. Concurrent bacterial cystitis was not associated with persistent postoperative incontinence. Age at the time of surgical correction had no effect on the rate of postoperative incontinence. Eight incontinent dogs were treated medically; three are continent with medication, three are improved but still incontinent, and two did not improve.

Animals↗
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Force plate analysis of triple pelvic osteotomy for the treatment of canine hip dysplasia.

Triple pelvic osteotomy was performed in 15 dogs with bilateral hip dysplasia. Ten dogs were treated bilaterally and five dogs were treated unilaterally. Ten untreated dogs with normal hips served as controls. Force plate analysis, lameness evaluation, and radiography were performed before surgery and at weeks 5, 10, 15, and 28. Three dogs treated unilaterally were euthanatized and the hips were examined grossly and microscopically. Force plate data indicated that young dysplastic dogs transmitted significantly less vertical force through the hip joints than normal dogs. The force transmitted through treated hips reached or approached control levels by week 28 and was significantly greater than the force transmitted through untreated hips. Clinical lameness resolved in 92% of limbs and progression of radiographically detectable degenerative joint disease was minimal. Gross and microscopic degenerative changes in the articular cartilage were similar in the treated and untreated hips. The synovial membrane was less reactive in treated hips.

Animals↗
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The effect of occlusive and semi-occlusive dressings on the healing of acute full-thickness skin wounds on the forelimbs of dogs.

This project compared the effects of hydrocolloid (HC) and hydrogel (HG) occlusive dressings and a polyethylene (PE) semi-occlusive dressing on the healing of acute full-thickness skin wounds on the forelimbs of 10 dogs. All treatments resulted in a similar degree of healing at postoperative days 4 and 7. No significant differences existed in the number of wounds that were more than 90% healed at postoperative day 28 between the group treated with the HG dressing and the group treated with the PE dressing. There were significantly fewer wounds more than 90% healed at postoperative day 28 in the group treated with the HC dressing. Wounds under the HG dressing had the largest mean percentage of contraction at postoperative days 21 and 28. Wounds under the HG dressing also had the largest contraction/re-epithelialization ratio (postoperative days 21 and 28) compared with wounds under the PE and HC dressings. Wounds under the PE dressing had a significantly higher mean percentage of re-epithelialization than wounds under both occlusive dressings on postoperative days 14, 21, and 28. Wounds under the two occlusive dressings had exuberant granulation tissue present more often than wounds under the PE dressing. The two occlusive dressings had significantly higher bacterial counts on wounds compared with wounds under the PE dressing; analysis of variance (ANOVA), P = .0008. Wounds under the HC dressing showed the poorest healing in all parameters.

Animals↗
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Venous gas embolism associated with argon-enhanced coagulation of the liver.

Argon-enhanced coagulation (AEC) is a method for operative coagulation of tissues that utilizes a jet of argon gas encompassing an electrofulguration arc. Concern has been raised that the argon jet may produce harmful venous gas embolization. Two questions were addressed by this study. First, does AEC result in generation of venous gas emboli, and if so, what is the influence of gas flow rate and coagulation power on the amount of gas emboli generated? Second, does the amount of venous gas emboli generated by AEC produce harmful hemodynamic effects? Two AEC units were evaluated during coagulation of cut sections of the liver in pigs. The number of gas emboli generated was measured by an ultrasonic Doppler flow cuff placed around the caudal vena cava. Hemodynamic variables measured following AEC included systemic and pulmonary arterial pressure, pulmonary wedge pressure, and cardiac output by thermodilution. Venous gas emboli were produced during AEC of the liver. The number of gas emboli generated increased with increasing gas flow rates, but was not affected by coagulation power. No change in any of the measured hemodynamic variables was observed following AEC of the liver. The following recommendations were made: (1) Surgeons using AEC should select an argon flow rate as low as feasible to clear a bleeding tissue surface of blood and debris. (2) Although AEC seems to be associated with tolerable amounts of venous gas embolism, surgeons and anesthesiologists should be aware that the potential for harmful venous gas embolism exists. (3) In patients where extensive use of AEC is planned, appropriate monitoring and precautions for gas embolism should be undertaken.

Animals↗
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Peripheral nerve sheath tumor of the diaphragm with osseous differentiation in a one-year-old dog.

A 12-month-old, spayed female German shepherd dog was referred to the Veterinary Teaching Hospital for repair of a diaphragmatic hernia. Abdominal exploration revealed an intact diaphragm, but thoracic exploration revealed a large mass originating from the diaphragm. Resection of the mass was incomplete and required reconstruction of the diaphragm. On histopathology, the mass was composed mainly of spindle-shaped cells with occasional areas of osseous and chondroid tissue. The tumor was diagnosed as a peripheral nerve sheath tumor (PNST) with chondro-osseous differentiation. The dog was released four days after surgery; however, she began having difficulty breathing seven days after discharge, and the owners elected euthanasia. A necropsy was not performed. This is the first known report of a PNST originating in the diaphragm of a dog.

Animals↗
PubMedDate not supplied

Kidney transplantation in dogs with naturally occurring end-stage renal disease.

Renal allografts were performed between unrelated donors and 15 dogs with naturally occurring end-stage renal disease. Donor selection was based on compatible dog erythrocyte antigen typing and cross-matching. An immunosuppressive protocol consisting of rabbit antidog antithymocyte serum, cyclosporin-A, azathioprine, and prednisone was used to control postoperative rejection of the donated kidney. Although seven animals died because of technical failures or rejection episodes, a median survival time of eight months has been achieved, with two dogs living for longer than five years after surgery. Long-term survivors have died from a variety of problems not related to renal allograft rejection.

Animals↗
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Mutant p53 proteins behave in a dominant, negative fashion in vivo.

The p53 encodes a cellular phosphoprotein that has been association with both neoplastic transformation and the control of cellular growth. Recent studies have reported that p53 also acts as a transcriptional regulator. We have studied transactivational properties of human wild-type and mutant p53 proteins representing 4 major mutational hotspots (codons 141, 175, 248, 273) as well as a double mutant Tyr141/His273 and a p53 with the transcriptional activating region removed (pcDC2). Transactivation by p53 was shown with a p53 concensus binding sequence controlled CAT reporter gene, and activity was assayed after co-transfection of the reporter with either wild-type or mutant p53 expression constructs. Wild-type p53 as well as one mutant p53 [(mutation of arginine to histidine at codon 273 (His 273)], had strong transactivating activity, but all other mutant p53s were inactive in transcriptional activation, including the double mutant Tyr141/His273 suggesting that the Tyr141 mutation was dominant over the His273 mutation in the same protein. Moreover, when mutant p53 (Tyr141, His175, Trp248, or Tyr141/His273) was cotransfected with either wild-type p53 or mutant His273 p53, these mutants inhibited the transactivation of coexpressed wild-type p53. The p53 vector (pcDC2), which contains p53 oligomerization sequences, but not the transactivational domain, markedly inhibited wild-type p53 transactivational activity. Each of the mutant p53s similarly inhibited the transactivation of His273 p53. Therefore, with the exception of His273, each of the other mutant p53 were unable to transactivate and each behaved in a dominant negative fashion.

Base Sequence↗
PubMedDate not supplied

Status of the p53, Rb and MDM2 genes in canine osteosarcoma.

The key role of p53 and Rb alterations in human osteosarcoma is clear. For example, osteosarcoma is common in individuals inheriting mutant p53 or Rb genes. Osteosarcoma in dogs is similar to humans by histology, site, gender ratio and several other biological parameters. To study whether this similarity extends to the molecular level, 21 canine osteosarcomas were analyzed for alterations of p53, Rb and MDM2. MDM2 is a normal cell protein which antagonizes p53, amplification is seen in some human sarcomas. The gross structure of the p53, Rb and MDM2 genes was examined by Southern blotting. No deletions or rearrangements of the p53 or Rb genes were detected. The absence of gross gene alterations affecting these tumor suppressor genes is a significant difference between the disease in dogs and humans, since rearrangements or deletions of the p53 or Rb genes occur in 20-30 per cent of human osteosarcomas. The MDM2 gene appeared to be duplicated in one canine tumor but no cases of significant amplification were detected. Expression of normal Rb was detected in all cases. Mutations of the p53 gene were found in 38 percent of canine osteosarcomas. Analysis of mutations revealed a predominance of spontaneous mutation. These finding emphasize the key role that alterations of p53 have in the development of osteosarcoma in dogs and humans.

Animals↗