Investigation and validation of a novel Endo GIA stapler for canine lung lobectomies.

The objectives of this study were to validate the 2.0 mm Endo GIA stapler for lung lobectomies and to compare procedural time and air leakage incidence with suture ligation. Sixteen canine cadavers, 18 to 27 kg, were randomly assigned to undergo lung lobectomy of the right middle lung lobe through intercostal thoracotomy, after which suture ligation or the 2.0 mm Endo GIA stapler was used. Procedural time was recorded. Following the lobectomy, the thoracic cavity was filled with fluid. Positive pressure ventilation was used to hold pressure at 20 cm H2O for 5 minutes. The bronchus was assessed for air leakage as evidenced by visualization of gas bubbles and the ability to maintain positive pressure. Procedural time and air leakage incidence were compared between groups. By these assessments, the 2.0 mm Endo GIA stapler was successful for lung lobectomies in all cadavers. There was no significant difference (t = -0.856, P = 0.407) in body weight by procedure assignment. Procedural time was significantly shorter (P < 0.0001) using the Endo GIA stapler compared to suture ligation. There was no significant correlation (r = 0.044, P = 0.873) between body weight and procedural time. There were no incidents of air leakage in either group. The 2.0 mm Endo GIA stapler may be used as an alternative device for lung lobectomies in canine cadavers. Smaller staples may provide more complete compression of hilar vessels and bronchi, resulting in reduced hemorrhage, air leakage, and thoracic contamination in cases with infection or neoplasia.

Examen et validation d'une nouvelle agrafeuse Endo GIA pour les lobectomies pulmonaires canines. Les objectifs de cette étude étaient de valider l'agrafeuse Endo GIA de 2,0 mm pour les lobectomies pulmonaires et de comparer le temps de procédure et l'incidence des fuites d'air avec la ligature par suture. Seize cadavres canins, de 18 à 27 kg, ont été randomisés pour subir une lobectomie pulmonaire du lobe pulmonaire moyen droit par thoracotomie intercostale, après quoi une ligature par suture ou l'agrafeuse Endo GIA de 2,0 mm a été utilisée. Le temps de la procédure a été enregistré. Après la lobectomie, la cavité thoracique a été remplie de liquide. Une ventilation à pression positive a été utilisée pour maintenir la pression à 20 cm H2O pendant 5 minutes. La bronche a été évaluée pour les fuites d'air comme en témoignent la visualisation des bulles de gaz et la capacité à maintenir une pression positive. Le temps de procédure et l'incidence des fuites d'air ont été comparés entre les groupes.D'après ces évaluations, l'agrafeuse Endo GIA de 2,0 mm a été efficace pour les lobectomies pulmonaires sur tous les cadavres. Il n'y avait pas de différence significative (t = −0,856, P = 0,407) dans le poids corporel selon l'attribution de la procédure. Le temps de procédure était significativement plus court (P < 0,0001) avec l'agrafeuse Endo GIA par rapport à la ligature par suture. Il n'y avait pas de corrélation significative (r = 0,044, P = 0,873) entre le poids corporel et le temps de procédure. Il n'y a eu aucun incident de fuite d'air dans les deux groupes. L'agrafeuse Endo GIA de 2,0 mm peut être utilisée comme dispositif alternatif pour les lobectomies pulmonaires sur les cadavres canins. Des agrafes plus petites peuvent fournir une compression plus complète des vaisseaux hilaires et des bronches, entraînant une réduction des hémorragies et des fuites d'air, ainsi qu'une réduction de la contamination thoracique en cas d'infection ou de néoplasie.(Traduit par Dr Serge Messier).

Effect of cold storage on immediate graft function in an experimental model of renal transplantation in cats.

OBJECTIVE To assess the effect of cold storage (CS) on immediate posttransplantation function of renal autografts in cats. ANIMALS 15 healthy 1-year-old cats. PROCEDURES Cats were assigned to 2 groups and underwent autotransplantation of the left kidney followed by nephrectomy of the right kidney. The left kidney was autotransplanted either immediately (IT group; n = 6) or after being flushed with a cold sucrose phosphate solution and stored on ice while the implant site was prepared (CS group; 9). Serum creatinine and BUN concentrations were monitored daily and autografts were ultrasonographically examined intermittently for 14 days after surgery. RESULTS Mean duration of CS was 24 minutes for the CS group. Posttransplantation serum creatinine and BUN concentrations for the CS group had lower peak values, returned to the respective reference ranges quicker, and were generally significantly lower than those for the IT group. Mean posttransplantation autograft size for the CS group was smaller than that for the IT group. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that immediate posttransplantation function of renal autografts following a short period of CS was better than that of renal autografts that did not undergo CS, which suggested CS protected grafts from ischemic injury and may decrease perioperative complications, speed recovery, and improve the long-term outcome for cats with renal transplants. IMPACT FOR HUMAN MEDICINE Cats metabolize immunosuppressive drugs in a manner similar to humans; therefore, renal transplantation in cats may serve as a desirable model for investigating the effects of renal transplantation in human patients.

Vascular hamartoma in the right ventricle of a dog: Diagnosis and treatment.

A 6-month old Labrador retriever was presented with an acute history of collapse during exercise. A grade III/VI left basilar systolic murmur and thoracic radiographs showing severe right heart enlargement with an enlarged main pulmonary artery were most consistent with a clinical diagnosis of pulmonic stenosis. Echocardiography revealed an intracardiac mass partially obstructing the right ventricular outflow tract. The mass was surgically excised, and histopathology diagnosed a benign vascular hamartoma of the right ventricle. Short-term follow-up showed resolution of clinical signs with no evidence of local recurrence. Intracardiac masses should be considered a differential diagnosis for patients with acute-onset syncope.

Radiographic risk factors for contralateral rupture in dogs with unilateral cranial cruciate ligament rupture.

BACKGROUND: Complete cranial cruciate ligament rupture (CR) is a common cause of pelvic limb lameness in dogs. Dogs with unilateral CR often develop contralateral CR over time. Although radiographic signs of contralateral stifle joint osteoarthritis (OA) influence risk of subsequent contralateral CR, this risk has not been studied in detail. METHODOLOGY/PRINCIPAL FINDINGS: We conducted a retrospective longitudinal cohort study of client-owned dogs with unilateral CR to determine how severity of radiographic stifle synovial effusion and osteophytosis influence risk of contralateral CR over time. Detailed survival analysis was performed for a cohort of 85 dogs after case filtering of an initial sample population of 513 dogs. This population was stratified based on radiographic severity of synovial effusion (graded on a scale of 0, 1, and 2) and severity of osteophytosis (graded on a scale of 0, 1, 2, and 3) of both index and contralateral stifle joints using a reproducible scoring method. Severity of osteophytosis in the index and contralateral stifles was significantly correlated. Rupture of the contralateral cranial cruciate ligament was significantly influenced by radiographic OA in both the index and contralateral stifles at diagnosis. Odds ratio for development of contralateral CR in dogs with severe contralateral radiographic stifle effusion was 13.4 at one year after diagnosis and 11.4 at two years. Odds ratio for development of contralateral CR in dogs with severe contralateral osteophytosis was 9.9 at one year after diagnosis. These odds ratios were associated with decreased time to contralateral CR. Breed, age, body weight, gender, and tibial plateau angle did not significantly influence time to contralateral CR. CONCLUSION: Subsequent contralateral CR is significantly influenced by severity of radiographic stifle effusion and osteophytosis in the contralateral stifle, suggesting that synovitis and arthritic joint degeneration are significant factors in the disease mechanism underlying the arthropathy.

Enhanced cytoprotective effects of the inhibitor of apoptosis protein cellular IAP1 through stabilization with TRAF2.

Inhibitor of apoptosis (IAP) proteins are key regulators of intracellular signaling that interact with tumor necrosis factor (TNF) receptor superfamily members as well as proapoptotic molecules such as Smac/DIABLO and caspases. Whereas the X-linked IAP is an established caspase inhibitor, the protective mechanisms utilized by the cellular IAP (c-IAP) proteins are less clear because c-IAPs bind to but do not inhibit the enzymatic activities of caspases. In this study, c-IAPs are shown to be highly unstable molecules that undergo autoubiquitination. The autoubiquitination of c-IAP1 is blocked upon coexpression with TNF receptor-associated factor (TRAF) 2, and this is achieved by inhibition of the E3 ubiquitin ligase activity intrinsic to the RING of c-IAP1. Consistent with these observations, loss of TRAF2 results in a decrease in c-IAP1 levels. Stabilized c-IAP1 was found to sequester and prevent Smac/DIABLO from antagonizing X-linked IAP and protect against cell death. Therefore, this study describes an intriguing cytoprotective mechanism utilized by c-IAP1 and provides critical insight into how IAP proteins function to alter the apoptotic threshold.

Two distinct signalling cascades target the NF-kappaB regulatory factor c-IAP1 for degradation.

c-IAP1 (cellular inhibitor of apoptosis 1) has recently emerged as a negative regulator of the non-canonical NF-kappaB (nuclear factor kappaB) signalling cascade. Whereas synthetic IAP inhibitors have been shown to trigger the autoubiquitination and degradation of c-IAP1, less is known about the physiological mechanisms by which c-IAP1 stability is regulated. In the present paper, we describe two distinct cellular processes that lead to the targeted loss of c-IAP1. Recruitment of a TRAF2 (tumour necrosis factor receptor-associated factor 2)-c-IAP1 complex to the cytoplasmic domain of the Hodgkin's/anaplastic large-cell lymphoma-associated receptor, CD30, leads to the targeting and degradation of the TRAF2-c-IAP1 heterodimer through a mechanism requiring the RING (really interesting new gene) domain of TRAF2, but not c-IAP1. In contrast, the induced autoubiquitination of c-IAP1 by IAP antagonists causes the selective loss of c-IAP1, but not TRAF2, thereby releasing TRAF2. Thus c-IAP1 can be targeted for degradation by two distinct processes, revealing the critical importance of this molecule as a regulator of numerous intracellular signalling cascades.

Apoptotic sensitivity of murine IAP-deficient cells.

Although numerous studies have implicated the IAPs (inhibitor of apoptosis proteins) in the control of apoptotic cell death, analyses of murine Iap-targeted cells have not revealed significant differences in their susceptibility to apoptosis. In the present study, we show that, under defined conditions, murine cells lacking XIAP (X-linked inhibitor of apoptosis) and c-IAP (cellular IAP) 2, but not c-IAP1, exhibit heightened apoptotic sensitivity to both intrinsic and extrinsic apoptotic stimuli.

Apoptosis-inducing factor is a target for ubiquitination through interaction with XIAP.

X-linked inhibitor of apoptosis (XIAP) is an inhibitor of apoptotic cell death that protects cells by caspase-dependent and independent mechanisms. In a screen for molecules that participate with XIAP in regulating cellular activities, we identified apoptosis-inducing factor (AIF) as an XIAP binding protein. Baculoviral IAP repeat 2 of XIAP is sufficient for the XIAP/AIF interaction, which is disrupted by Smac/DIABLO. In healthy cells, mature human AIF lacks only the first 54 amino acids, differing significantly from the apoptotic form, which lacks the first 102 amino-terminal residues. Fluorescence complementation and immunoprecipitation experiments revealed that XIAP interacts with both AIF forms. AIF was found to be a target of XIAP-mediated ubiquitination under both normal and apoptotic conditions, and an E3 ubiquitin ligase-deficient XIAP variant displayed a more robust interaction with AIF. Expression of either XIAP or AIF attenuated both basal and antimycin A-stimulated levels of reactive oxygen species (ROS), and when XIAP and AIF were expressed in combination, a cumulative decrease in ROS was observed. These results identify AIF as a new XIAP binding partner and indicate a role for XIAP in regulating cellular ROS.

XIAP Is a copper binding protein deregulated in Wilson's disease and other copper toxicosis disorders.

X-linked inhibitor of apoptosis (XIAP), known primarily for its caspase inhibitory properties, has recently been shown to interact with and regulate the levels of COMMD1, a protein associated with a form of canine copper toxicosis. Here, we describe a role for XIAP in copper metabolism. We find that XIAP levels are greatly reduced by intracellular copper accumulation in Wilson's disease and other copper toxicosis disorders and in cells cultured under high copper conditions. Elevated copper levels result in a profound, reversible conformational change in XIAP due to the direct binding of copper to XIAP, which accelerates its degradation and significantly decreases its ability to inhibit caspase-3. This results in a lowering of the apoptotic threshold, sensitizing the cell to apoptosis. These data provide an unsuspected link between copper homeostasis and the regulation of cell death through XIAP and may contribute to the pathophysiology of copper toxicosis disorders.

COMMD proteins, a novel family of structural and functional homologs of MURR1.

MURR1 is a multifunctional protein that inhibits nuclear factor kappaB (NF-kappaB), a transcription factor with pleiotropic functions affecting innate and adaptive immunity, apoptosis, cell cycle regulation, and oncogenesis. Here we report the discovery of a new family of proteins with homology to MURR1. These proteins form multimeric complexes and were identified in a biochemical screen for MURR1-associated factors. The family is defined by the presence of a conserved and unique motif termed the COMM (copper metabolism gene MURR1) domain, which functions as an interface for protein-protein interactions. Like MURR1, several of these factors also associate with and inhibit NF-kappaB. The proteins designated as COMMD or COMM domain containing 1-10 are extensively conserved in multicellular eukaryotic organisms and define a novel family of structural and functional homologs of MURR1. The prototype of this family, MURR1/COMMD1, suppresses NF-kappaB not by affecting nuclear translocation or binding of NF-kappaB to cognate motifs; rather, it functions in the nucleus by affecting the association of NF-kappaB with chromatin.

Neutralization of Smac/Diablo by inhibitors of apoptosis (IAPs). A caspase-independent mechanism for apoptotic inhibition.

Numerous members of the IAP family can suppress apoptotic cell death in physiological settings. Whereas certain IAPs directly inhibit caspases, the chief proteolytic effectors of apoptosis, the protective effects of other IAPs do not correlate well with their caspase inhibitory activities, suggesting the involvement of alternative cytoprotective abilities. To examine this issue, we have characterized the protective effects of an ancestral, baculoviral IAP (Op-IAP) in mammalian cells. We show that although Op-IAP potently inhibited Bax-mediated apoptosis in human cells, Op-IAP failed to directly inhibit mammalian caspases. However, Op-IAP efficiently bound the IAP antagonist Smac/Diablo, thereby preventing Smac/Diablo-mediated inhibition of cellular IAPs. Whereas reduction of Smac/Diablo protein levels in the absence of Op-IAP prevented Bax-mediated apoptosis, overexpression of Smac/Diablo neutralized Op-IAP-mediated protection, and an Op-IAP variant unable to bind Smac/Diablo failed to prevent apoptosis. Finally, Op-IAP catalyzed the ubiquitination of Smac/Diablo, an activity that contributed to Op-IAP-mediated inhibition of apoptosis. These data show that cytoprotective IAPs can inhibit apoptosis through the neutralization of IAP antagonists, rather than by directly inhibiting caspases.