Genomic analysis across 53 canine cancer types reveals novel mutations and high clinical actionability potential

A genomic understanding of the oncogenic processes and individual variability of human cancer has steadily fueled improvement in patient outcomes over the past 20 years. Mutations within tumour tissues are routinely assessed through clinical genomic diagnostic assays by academic and commercial laboratories to facilitate diagnosis, prognosis and effective treatment stratification. The application of genomics has unveiled a wealth of mutation-based biomarkers in canine cancers, suggesting that the transformative principles that have revolutionized human cancer medicine can be brought to bear in veterinary oncology. To advance clinical genomics and genomics-guided medicine in canine oncology, we have developed and validated a canine cancer next-generation sequencing gene panel for the identification of multiple mutation types in clinical specimens. With this panel, we examined the genomic landscapes of 828 tumours from 813 dogs, spanning 53 cancer types. We identified 7856 alterations, encompassing copy number variants, single nucleotide variants, indels and internal tandem duplications. Additionally, we evaluated the clinical utility of these alterations by incorporating a biomarker framework from comprehensive curation of primary canine literature and inferences from human cancer genomic biomarker literature and clinical diagnostics. Remarkably, nearly 90% of the cases exhibited mutations with diagnostic, prognostic or therapeutic implications. Our work represents a thorough assessment of genomic landscapes in a large cohort of canine cancers, the first of its kind for its comprehensive inclusion of multiple mutation types and structured annotation of biomarkers, demonstrating the clinical potential of leveraging mutation-based biomarkers in veterinary oncology.

Standing in the canine precision medicine knowledge gap: Improving annotation of canine cancer genomic biomarkers through systematic comparative analysis of human cancer mutations in COSMIC

The accrual of cancer mutation data and related functional and clinical associations have revolutionised human oncology, enabling the advancement of precision medicine and biomarker-guided clinical management. The catalogue of cancer mutations is also growing in canine cancers. However, without direct high-powered functional data in dogs, it remains challenging to interpret and utilise them in research and clinical settings. It is well-recognised that canine and human cancers share genetic, molecular and phenotypic similarities. Therefore, leveraging the massive wealth of human mutation data may help advance canine oncology. Here, we present a structured analysis of sequence conservation and conversion of human mutations to the canine genome through a 'caninisation' process. We applied this analysis to COSMIC, the Catalogue of Somatic Mutations in Cancer, the most prominent human cancer mutation database. For the project's initial phase, we focused on the subset of the COSMIC data corresponding to Cancer Gene Census (CGC) genes. A total of 670 canine orthologs were found for 721 CGC genes. In these genes, 365 K unique mutations across 160 tumour types were converted successfully to canine coordinates. We identified shared putative cancer-driving mutations, including pathogenic and hotspot mutations and mutations bearing similar biomarker associations with diagnostic, prognostic and therapeutic utility. Thus, this structured caninisation of human cancer mutations facilitates the interpretation and annotation of canine mutations and helps bridge the knowledge gap to enable canine precision medicine.

Genomic tumor analysis provides clinical guidance for the management of diagnostically challenging cancers in dogs

OBJECTIVE

To evaluate the diagnostic, prognostic, and therapeutic utility of a cancer genomic diagnostic assay (SearchLight DNA; Vidium Animal Health) for diagnostically ambiguous cancer cases.

ANIMALS

69 privately owned dogs with ambiguous cancer diagnoses and for which the genomic assay was performed.

PROCEDURES

Genomic assay reports generated between September 28, 2020, and July 31, 2022, for dogs with malignancy or suspected malignancy were reviewed to determine the assay's clinical utility defined as providing diagnostic clarity, prognostic information, and/or therapeutic options.

RESULTS

Genomic analysis provided diagnostic clarity in 37 of 69 cases (54%; group 1) and therapeutic and/or prognostic information in 22 of the remaining 32 cases (69%; group 2) for which the diagnosis remained elusive. Overall, the genomic assay was clinically useful in 86% (59/69) of cases.

CLINICAL RELEVANCE

To our knowledge, this was the first study to evaluate the multifaceted clinical utility of a single cancer genomic test in veterinary medicine. Study findings supported the use of tumor genomic testing for dogs with cancer, particularly those that are diagnostically ambiguous and therefore inherently challenging to manage. This evidence-driven genomic assay provided diagnostic guidance, prognostic support, and therapeutic options for most patients with an unclear cancer diagnosis that would otherwise have an unsubstantiated clinical plan. Furthermore, 38% (26/69) of samples were easily obtained aspirates. Sample factors (sample type, percentage of tumor cells, and number of mutations) did not influence diagnostic yield. Our study demonstrated the value of genomic testing for the management of canine cancer.

International Guidelines for Veterinary Tumor Pathology: A Call to Action

Standardization of tumor assessment lays the foundation for validation of grading systems, permits reproducibility of oncologic studies among investigators, and increases confidence in the significance of study results. Currently, there is minimal methodological standardization for assessing tumors in veterinary medicine, with few attempts to validate published protocols and grading schemes. The current article attempts to address these shortcomings by providing standard guidelines for tumor assessment parameters and protocols for evaluating specific tumor types. More detailed information is available in the Supplemental Files, the intention of which is 2-fold: publication as part of this commentary, but more importantly, these will be available as "living documents" on a website (www.vetcancerprotocols.org), which will be updated as new information is presented in the peer-reviewed literature. Our hope is that veterinary pathologists will agree that this initiative is needed, and will contribute to and utilize this information for routine diagnostic work and oncologic studies. Journal editors and reviewers can utilize checklists to ensure publications include sufficient detail and standardized methods of tumor assessment. To maintain the relevance of the guidelines and protocols, it is critical that the information is periodically updated and revised as new studies are published and validated with the intent of providing a repository of this information. Our hope is that this initiative (a continuation of efforts published in this journal in 2011) will facilitate collaboration and reproducibility between pathologists and institutions, increase case numbers, and strengthen clinical research findings, thus ensuring continued progress in veterinary oncologic pathology and improving patient care.

Anaplastic Large T-Cell Lymphoma in the Intestine of Dogs

Anaplastic large T-cell lymphoma (ALTCL) is a rare subtype of non-Hodgkin T-cell lymphoma that occasionally occurs in the gastrointestinal tract of humans. Enteropathy-associated T-cell lymphoma (EATL) type 1 is the most common type of intestinal lymphoma in dogs, and ALTCL has not previously been reported in the intestinal tract of dogs. Thirteen dogs with intestinal masses diagnosed as intestinal lymphoma with anaplastic morphology were reviewed. Clinical data, including treatment protocols, were available for 11 cases. Immunohistochemistry for CD3, CD20, and CD30 was performed for all cases in addition to PCR for Antigen Receptor Rearrangements (PARR) for assessment of clonality. Eight (62%) of the cases presented with intestinal perforation, and all cases had 1 or more masses arising from the small intestine. Histologically, all cases were characterized by transmural infiltrates of large, CD3-positive and frequently CD30-positive cells. Neoplastic T cells had marked anisocytosis and anisokaryosis, prominent nucleoli, and occasionally indented to reniform nuclei. There was abundant necrosis and inflammation with occasional vascular invasion within neoplastic masses. All cases had a monoclonal T-cell receptor γ gene rearrangement. The median survival time was 5 days, with 1 dog surviving 2 years after the initial diagnosis. ALTCL can occur as an aggressive transmural lymphoma in the gastrointestinal tract of dogs and commonly causes intestinal perforation. ALTCL can be differentiated from EATL type 1 and might have implications for accurate prognostication and selection of therapeutic options in the future.

Transcriptome analysis of Frog virus 3, the type species of the genus Ranavirus, family Iridoviridae

Frog virus 3 is the best characterized species within the genus Ranavirus, family Iridoviridae. FV3's large ( approximately 105 kbp) dsDNA genome encodes 98 putative open reading frames (ORFs) that are expressed in a coordinated fashion leading to the sequential appearance of immediate early (IE), delayed early (DE) and late (L) viral transcripts. As a step toward elucidating molecular events in FV3 replication, we sought to identify the temporal class of viral messages. To accomplish this objective an oligonucleotide microarray containing 70-mer probes corresponding to each of the 98 FV3 ORFs was designed and used to examine viral gene expression. Viral transcription was initially monitored during the course of a productive replication cycle at 2, 4 and 9 h after infection. To confirm results of the time course assay, viral gene expression was also monitored in the presence of cycloheximide (CHX), which limits expression to only IE genes, and following infection with a temperature-sensitive (ts) mutant which at non-permissive temperatures is defective in viral DNA synthesis and blocked in late gene expression. Subsequently, microarray analyses were validated by RT-PCR and qRT-PCR. Using these approaches we identified 33 IE genes, 22 DE genes and 36 L viral genes. The temporal class of the 7 remaining genes could not be determined. Comparison of protein function with temporal class indicated that, in general, genes encoding putative regulatory factors, or proteins that played a part in nucleic acid metabolism and immune evasion, were classified as IE and DE genes, whereas those involved in DNA packaging and virion assembly were considered L genes. Information on temporal class will provide the basis for determining whether members of the same temporal class contain common upstream regulatory regions and perhaps allow us to identify virion-associated and virus-induced proteins that control viral gene expression.

Treatment of symptomatic primary chylous disorders

PURPOSE

Primary chylous disorders (PCDs) are rare. Rupture of dilated lymph vessels (lymphangiectasia) may result in chylous ascites, chylothorax, or leakage of chyle through chylocutanous fistulas in the lower limbs or genitalia. Chyle may reflux through incompetent lymphatics, causing lymphedema. To assess the efficacy of surgical treatment, we reviewed our experience.

METHODS

The clinical data of 35 patients with PCDs treated between January 1, 1976, and August 31, 2000, were reviewed retrospectively.

RESULTS

Fifteen men and 20 women (mean age, 29 years; range, 1 day-81 years) presented with PCDs. Sixteen (46%) patients had chylous ascites, and 19 (54%) had chylothorax (20 patients), and of these, 10 (29%) had both. In 16 patients, reflux of chyle into the pelvic or lower limb lymphatics caused lymphedema (14, 88%) or lymphatic leak through cutaneous fistulae (11, 69%). Presenting symptoms included lower-limb edema (19, 54%), dyspnea (17, 49%), scrotal or labial edema (15, 43%), or abdominal distention (13, 37%). Primary lymphangiectasia presented alone in 23 patients (66%), and it was associated with clinical syndromes or additional pathologic findings in 12 (yellow nail syndrome in 4, lymphangiomyomatosis in 3, unknown in 3, Prasad syndrome (hypogammaglobulinemia, lymphadenopathy, and pulmonary insufficiency) in 1, and thoracic duct cyst in 1). Twenty-one (60%) patients underwent 26 surgical procedures. Preoperative imaging included computed tomography scan in 15 patients, magnetic resonance imaging in 3, lymphoscintigraphy in 12, and lymphangiography in 14. Fifteen patients underwent 18 procedures for chylous ascites or pelvic reflux. Ten (56%) procedures were resection of retroperitoneal/mesenteric lymphatics with or without sclerotherapy of lymphatics, 4 (22%) were lymphovenous anastomoses or grafts, 3 (17%) were peritoneovenous shunts, and 1 (6%) patient had a hysterectomy. Six patients underwent eight procedures for chylothorax, including thoracotomy with decortication and pleurodesis (4 procedures), thoracoscopic decortication (1 patient), ligation of thoracic duct (2 procedures), and resection of thoracic duct cyst (1 patient). Postoperative mean follow-up was 54 months (range, 0.3-276). Early complications included wound infections in 3 patients, elevated liver enzymes in 1, and peritoneovenous shunt occlusion with innominate vein occlusion in 1. All patients improved initially, but four (19%) had recurrence of symptoms at a mean of 25 months (range, 1-43). Three patients had postoperative lymphoscintigraphy confirming improved lymphatic transport and diminished reflux. One patient died 12 years postoperatively, from causes unrelated to PCD.

CONCLUSIONS

More than half of the patients with PCDs require surgical treatment, and surgery should be considered in patients with significant symptoms of PCD. Lymphangiography is recommended to determine anatomy and the site of the lymphatic leak, especially if lymphovenous grafting is planned. All patients had initial benefit postoperatively and two thirds of patients demonstrated durable clinical improvement after surgical treatment.

Endovascular repair of a traumatic infrarenal aortic transection: a case report and review

Blunt abdominal aortic trauma occurs in up to 0.04% of all nonpenetrating traumas. Although uncommon, mortality from this injury ranges from 18% to 37%. Seat belt injury is associated with almost 50% of reported blunt abdominal aortic traumas. The authors present the case of a 21-year-old man, a restrained passenger who was involved in a high-speed motor vehicle accident. In the emergency room, he had obvious evidence of lap-belt injury. His peripheral pulses were normal and there was no pulsatile abdominal mass. Computer tomography (CT) revealed a large amount of free intraperitoneal fluid throughout with signs of mesenteric avulsion and fracture/dislocation of T11-T12. The patient underwent an exploratory laparotomy. Right hemicolectomy and resection of small bowel was performed. CT angiography revealed an aortic transection and surrounding pseudoaneurysm 2 cm above the aortic bifurcation. The patient returned to the operating room for endovascular repair. Via a right femoral cutdown, a 14 mm x 5.5 cm stent-graft was placed across the distal abdominal aorta. Follow-up arteriogram revealed complete obliteration of the pseudoaneurysm without evidence of leak. There were no complications related to the aortic stent-graft in the postoperative period. The patient was discharged in good condition. As this case demonstrates, endovascular repair of traumatic aortic injury is feasible and may represent an improved treatment in certain settings.

Mutual exclusion of apoptosis and hsp70 in human vein intimal hyperplasia in vitro

BACKGROUND

Apoptosis of vascular smooth muscle cells (VSMC) plays a role in physiological vascular remodeling, as well as in disease states such as atherosclerosis and restenosis after angioplasty. Heat shock protein 70 (hsp70) may protect the cell against apoptosis and/or necrosis. In this study, we examined hsp70 expression and its temporal relationship to cell survival or death in a model of intimal vein hyperplasia in vitro.

METHODS

Segments of human saphenous veins were placed into culture. At different days vein segments were serum-starved or exposed to heat shock. Apoptosis and hsp70 expression were analyzed by Western blot, immunohistochemistry, and TUNEL assay.

RESULTS

A marked intimal vein hyperplasia developed after 14 days of culture when compared with baseline. hsp70 was present at baseline and disappeared during culture. Heating during culture could not up-regulate hsp70. The apoptotic markers were absent at baseline and present during normal culture. Conversely, serum starvation stimulated strong hsp70 expression coincidental with the disappearance of apoptotic markers.

CONCLUSIONS

Stimulation of veins during culture with serum resulted in hyperplasia, apoptosis, and inhibition of hsp70 expression. Down-regulation of hsp70 may permit apoptosis and vessel wall remodeling in this model.

Psychological distress in grandmother kinship care providers: the role of resources, social support, and physical health

OBJECTIVE

The purpose of the present study was to investigate predictors of psychological distress in grandmother kinship care providers. More specifically, it was hypothesized that social support, family resources, and physical health would predict psychological distress in grandmothers raising grandchildren.

METHOD

One hundred and two grandmothers raising grandchildren in parent-absent homes completed the Brief Symptom Inventory, Short Health Form-36, Family Resource Scale, Family Support Scale, and a questionnaire requesting background and demographic data.

RESULTS

Results indicated that psychological distress was predicted by family resources, participants' physical health, and to a lesser extent, social support.

CONCLUSION

The findings indicate that family resources, social support, and physical health affected psychological distress in grandmothers raising grandchildren. Grandmothers who reported fewer resources, less social support, and poorer physical health tended to experience higher levels of psychological distress. This study suggests that greater attention be given to interventions aimed to decrease psychological distress and improve the financial resources and physical health of grandmothers raising grandchildren.

Editorial Introduction

There is exciting news! The International Society for Genetic Algorithms (ISGA) and Genetic Programming, Inc. have joined efforts, recombined, and organized a new society: The International Society for Genetic and Evolutionary Computation (ISGEC). This follows the merger of the International Conference on Genetic Algorithms and the Genetic Programming Conference into a single conference: The Genetic and Evolutionary Computation Conference (GECCO). This is exciting because the new society will have dues that include a subscription to Evolutionary Computation as well as the new journal Genetic Programming and Evolvable Machines. This will help to link Evolutionary Computation more directly to the community that founded it and to associate the journal with a large body of researchers and application developers that would appear to be its natural readership. The journal Evolutionary Computation was founded as a grassroots effort and with a spirit of cooperation that embraced all aspects of the field. The new society builds on this theme.

Predicting epistasis from mathematical models

Classically, epistasis is either computed exactly by Walsh coefficients or estimated by sampling. Exact computation is usually of theoretical interest since the computation typically grows exponentially with the number of bits in the domain. Given an evaluation function, epistasis also can be estimated by sampling. However this approach gives us little insight into the origin of the epistasis and is prone to sampling error. This paper presents theorems establishing the bounds of epistasis for problems that can be stated as mathematical expressions. This leads to substantial computational savings for bounding the difficulty of a problem. Furthermore, working with these theorems in a mathematical context, one can gain insight into the mathematical origins of epistasis and how a problem's epistasis might be reduced. We present several new measures for epistasis and give empirical evidence and examples to demonstrate the application of the theorems. In particular, we show that some functions display "parity" such that by picking a well-defined representation, all Walsh coefficients of either odd or even index become zero, thereby reducing the nonlinearity of the function.

Cell-free hemoglobin preserves renal function during normothermic ischemia

INTRODUCTION

The purpose of this study is to determine whether an infusion of polymerized hemoglobin solution is capable of suppressing the tubular damage and loss of renal function normally seen during a clinically relevant period of warm ischemia.

METHODS

Male rats (350-450 g) were randomized to treatment with control (5% human serum albumin, HSA, n = 6) or test solution (9% polymerized hemoglobin, PHB, n = 6). Following a right nephrectomy, the left renal artery was perfused with 4 ml of HSA or PHB at 37 degreesC. The left renal artery was temporarily occluded for 50 min. At 72 h, creatinine (Cr), blood urea nitrogen (BUN), and percentage hemoglobin (Hb) were measured and the kidney was removed. Stained kidney sections were graded for ischemic injury (0-4, 0 = normal and 4 = necrosis of the proximal tubule). All results were expressed as means +/- SEM and statistical analysis was performed by t test.

RESULTS

Treatment with PHB resulted in lower Cr (1.2 +/- 0.23 mg/dl vs 3.26 +/- 0.60 mg/dl, P < 0.01) and BUN (60.5 +/- 12.7 mg/dl vs 151 +/- 20.2 mg/dl, P < 0.01) at 72 h compared to HSA controls. Total hemoglobin was not significantly different at 72 h. The weight of all treated kidneys increased; however, the increase was significantly less in the PHB-treated group (34 +/- 9.1% vs 70 +/- 7. 4%, P < 0.01). PHB-treated kidneys had less evidence of histologic damage compared to those in the HSA group (0.75 +/- 0.11 vs 2.50 +/- 0.64, P < 0.05).

CONCLUSIONS

During normothermic renal ischemia, renal artery infusion of PHB resulted in preservation of renal function and histologic architecture. PHB solutions may be useful in preserving organ function during prolonged periods of in vivo ischemia.

Midaortic pseudoaneurysm complicating extensive endovascular stenting of aortic disease

We report a case of successful surgical management of a potentially life-threatening complication of aortoiliac stent placement. A 59-year-old man who had Leriche syndrome underwent bilateral iliac artery and infrarenal aortic stent placement at another institution. His history was significant for retroperitoneal lymph node dissection at 19 years of age for testicular cancer. One week after stent placement, the patient was readmitted with abdominal pain, poor oral intake, and diffuse intermittent tenderness. Evaluation with computed tomographic scanning and endoscopy was unremarkable, and the patient was discharged. He was admitted to our institution 1 week later with persistent abdominal pain. A computed tomographic scan of the abdomen revealed a large pseudoaneurysm of the abdominal aorta. The patient underwent urgent exploration, and exclusion of his infrarenal aorta was achieved with aortobifemoral bypass grafting. After the operation, the patient's course was complicated by a large paraduodenal hematoma, which resulted in a gastric outlet obstruction, which was managed without operation. This case illustrates a potential life-threatening complication of extensive stent placement for aortoiliac occlusive disease. Injury to the abdominal aorta must be considered in a symptomatic patient after the placement of stents in the aortoiliac region, beyond the immediate periprocedural period.

To grandmother's house we go ... and stay. Children raised in intergenerational families

An increased incidence in child abuse and neglect has resulted in a dramatic rise in the number of grandparents raising grandchildren and great-grandchildren. Grandchildren raised by grandparents often suffer from emotional and behavioral problems due to prior abuse, neglect, and abandonment. Grandparent caregivers experience increased health problems, psychological distress, and social isolation related to their roles as primary caregivers of children. Grandparents who become caregivers of grandchildren face increased financial responsibilities at a time in their lives, close to or at retirement, when income is dramatically decreased.

Critical pathways and cost-effective practice

With increasing pressure by third-party payers and federal reimbursement systems to reduce health care expenditures, cost-effective means to care for the resource intensive vascular surgical population must be explored. The challenge of meeting these cost-saving priorities while maintaining or improving quality of care can result in conflicting demands on surgeons, particularly in academic practices. The adaptation of an industrial management tool-the critical pathway method-to health care delivery is an attempt to reduce length of stay and improve efficiency. Utilization of vascular nurse practitioners, concentration of vascular patients into a dedicated unit, reduction in angiography through more aggressive use of the vascular laboratory, and optimal use of rehabilitation units and skilled nursing facilities are important adjuncts to reduce length of stay without sacrificing quality of care. This report describes the critical pathway method as implemented in a university teaching hospital, and the integration of other modalities in the care of vascular patients that has reduced length of stay by as much as 40% for some vascular surgical procedures.

Effect of a femoral arteriovenous fistula on lower extremity venous hemodynamics after femorocaval reconstruction

PURPOSE

To study the hemodynamic effects of an arteriovenous fistula (AVF) used as an adjunct to venous reconstructions and to determine the optimal size for such a fistula.

METHODS

A model of limb circulation with an AVF (in vitro system) was constructed with silicon elastic tubes and 40% glycerin solution as the fluid medium. Pulsatile arterial flow and venous return was maintained with a roller pump and a centrifugal assist device. Flows and pressures were measured for three different fistula diameters (3, 4, and 5 mm). A canine model of venous hypertension with outflow obstruction was constructed in 15 adult mongrel dogs. After 7 to 13 days an externally supported 8-mm expanded polytetrafluoroethylene femorocaval graft was implanted with a distal AVF (3 mm, n = 5; 4 mm, n = 5; 5 mm, n = 5). Arterial and venous flows and venous pressures were measured proximal and distal to the fistula before and after exercise.

RESULTS

In the in vitro system, flows through the venous graft increased with increasing fistula size, but venous return decreased progressively, increasing the distal venous pressure. In the canine model, flow in the venous graft increased with each AVF (p < 0.01). Only the 3-mm AVF resulted in decreased distal femoral vein pressure (p < 0.01), orthograde flow, and improved venous return with exercise.

CONCLUSION

AVFs increased flow through the femorocaval grafts, yet they impeded venous return. The ideal AVF-to-graft ratio used in our study was 0.375, because it increased graft flow, permitted forward flow in the femoral vein while reducing pressure, and improved venous return with exercise.

Predictive value of carotid artery stump pressures during carotid endarterectomy

The ideal method of monitoring cerebral perfusion during carotid endarterectomy remains controversial. This article reviews many of the larger studies in the literature that have attempted to evaluate the usefulness of carotid artery stump pressure. Topics discussed include stump pressure alone, regional anesthesia, stump pressure and EEG, and stump pressures and transcranial Doppler ultrasonography.

Urokinase treatment preserves endothelial and smooth muscle function in experimental acute arterial thrombosis

PURPOSE

Pharmacologic lysis or balloon thrombectomy are options to treat acute arterial thrombosis; however, little is known about their effects on functional changes in the arterial wall. The aim of this study was to determine function of the endothelium and smooth muscle in canine arteries revascularized after acute thrombosis with balloon thrombectomy or lytic therapy.

METHODS

Acute thrombosis was obtained by bilateral proximal and distal ligation of 8-cm. segments of the femoral arteries in dogs. After 24 hours, the ties were removed and the arteries randomized to treatment groups: group 1, balloon thrombectomy (# 4 Fogarty balloon catheter at 60 grams linear shear x 1 pass, n = 7); group 2, untreated, tie removal only (n = 6); group 3, regional intra-arterial urokinase infusion (4000 U/min x 90 min, n = 6); group 4, regional intra-arterial carrier infusion (0.43 ml/min x 90 min, n = 6); group 5, unoperated normal vessels (n = 5). After treatment, the arteries were removed and endothelial and smooth muscle responses examined in organ chambers. Endothelial loss was graded with light microscopy of vessel rings from each animal by an observer blinded to the treatment group. Findings were confirmed with scanning electron microscopy.

RESULTS

Treatment with urokinase did not alter endothelium-dependent relaxations or smooth muscle contractions compared with carrier infusion or untreated alone. Balloon catheter thrombectomy significantly reduced endothelium-dependent relaxations compared with all other groups in response to acetylcholine, bradykinin, and thrombin (p < 0.001). Contractions of smooth muscle in response to potassium chloride (60 mol/L) and phenylephrine (1 x 10-6 mol/L) were also reduced (p < 0.05). Rings from balloon thrombectomized arteries contracted in response to calcium ionophore A23187 (p < 0.001); these contractions were endothelium dependent and not reduced by indomethacin or blockade of endothelin A and B receptors. No significant differences in percentage of endothelial coverage between groups were assessed by light and electron microscopy.

CONCLUSION

Thrombolysis with urokinase caused no or minimal abnormalities in endothelial and smooth muscle function. Endothelium present after balloon thrombectomy produces contractile factors. Although the duration and recovery of these abnormalities in function are unknown, these findings support preferential use of urokinase over balloon thrombectomy when possible in acute arterial thrombosis or embolism.