Outcomes of 25 female dogs treated for ectopic ureters by open surgery or cystoscopic-guided laser ablation.

OBJECTIVE: To report outcomes after the correction of ectopic ureter (EU) by open surgery or cystoscopic-guided laser ablation (CLA) in female dogs. STUDY DESIGN: Retrospective study from 2011 to 2018. ANIMALS: Twenty-five female dogs. METHODS: Data collected included signalment, clinicopathologic data, procedural data, complications, and short-term and long-term outcomes. Complications were graded as minor or major if a surgical revision was required. Continence status was scored subjectively (1 = completely incontinent to 10 = fully continent). RESULTS: Fifteen dogs had bilateral EU and 24 had intramural EU (iEU). Open surgical correction included 13 neoureterostomies, 2 neocystoureterostomies, and a combination of these in 2 dogs. Eight dogs underwent CLA. Eighteen dogs experienced minor complications (72%), and 2 experienced major complications (8%). One-month postoperative continence was achieved in 20/25 (80%) dogs (median score of 10). Incontinence recurred at a median time of 24.9 months in 5 dogs but responded to medical treatment. Overall, dogs remained continent for 66 months (median) and 22/25 (88%) dogs achieved continence with adjunction of medical/surgical treatment in incontinent ones. Fewer minor complications and postoperative recurrences of incontinence were documented after CLA than neoureterostomy (P < .01 and P < .05). CONCLUSION: Ectopic ureter correction by open surgery or CLA resulted in a subjectively good prognosis, most dogs reaching continence within a month of surgery, although incontinence occasionally recurred in the long term. CLA was associated with fewer complications and incontinence recurrences than neoureterostomy. CLINICAL SIGNIFICANCE: Cystoscopic-guided laser ablation should be preferred to correct iEU to prevent short-term complications and the recurrence of incontinence. Further studies should investigate the cause of postoperative recurrence of urinary incontinence.

Pharmacokinetics and tolerance of repeated oral administration of 5-fluorocytosine in healthy dogs.

BACKGROUND: 5-fluorocytosine is a pyrimidine and a fluorinated cytosine analog mainly used as an antifungal agent. It is a precursor of 5-fluorouracil, which possesses anticancer properties. To reduce systemic toxicity of 5-fluorouracil during chemotherapy, 5- fluorocytosine can be used as a targeted anticancer agent. Expression of cytosine deaminase by a viral vector within a tumor allows targeted chemotherapy by converting 5-fluorocytosine into the cytotoxic chemotherapeutic agent 5-fluorouracil. However, little is known about the tolerance of 5-fluorocytosine in dogs after prolonged administration. RESULTS: In three healthy Beagle dogs receiving 100 mg/kg of 5-fluorocytosine twice daily for 14 days by oral route, non-compartmental pharmacokinetics revealed a terminal elimination half-life of 164.5 ± 22.5 min at day 1 and of 179.2 ± 11.5 min, after 7 days of administration. Clearance was significantly decreased between day 1 and day 7 with 0.386 ± 0.031 and 0.322 ± 0.027 ml/min/kg, respectively. Maximal plasma concentration values were below 100 µg/ml, which is considered within the therapeutic margin for human patients. 5-fluorouracil plasma concentration was below the limit of detection at all time points. The main adverse events consisted of depigmented, ulcerated, exudative, and crusty cutaneous lesions 10 to 13 days after beginning 5-fluorocytosine administration. The lesions were localized to the nasal planum, the lips, the eyelids, and the scrotum. Histological analyses were consistent with a cutaneous lupoid drug reaction. Complete healing was observed 15 to 21 days after cessation of 5-fluorocytosine. No biochemical or hematological adverse events were noticed. CONCLUSIONS: Long term administration of 5-fluorocytosine was associated with cutaneous toxicity in healthy dogs. It suggests that pharmacotherapy should be adjusted to reduce the toxicity of 5-fluorocytosine in targeted chemotherapy.

Safety studies and viral shedding of intramuscular administration of oncolytic vaccinia virus TG6002 in healthy beagle dogs.

BACKGROUND: Cancer is a leading cause of mortality for both humans and dogs. As spontaneous canine cancers appear to be relevant models of human cancers, developing new therapeutic approaches could benefit both species. Oncolytic virotherapy is a promising therapeutic approach in cancer treatment. TG6002 is a recombinant oncolytic vaccinia virus deleted in the thymidine kinase and ribonucleotide reductase genes and armed with the suicide gene FCU1 that encodes a protein which catalyses the conversion of the non-toxic 5-fluorocytosine into the toxic metabolite 5-fluorouracil. Previous studies have shown the ability of TG6002 to infect and replicate in canine tumor cell lines, and demonstrated its oncolytic potency in cell lines, xenograft models and canine mammary adenocarcinoma explants. Moreover, 5-fluorouracil synthesis has been confirmed in fresh canine mammary adenocarcinoma explants infected with TG6002 with 5-fluorocytosine. This study aims at assessing the safety profile and viral shedding after unique or repeated intramuscular injections of TG6002 in seven healthy Beagle dogs. RESULTS: Repeated intramuscular administrations of TG6002 at the dose of 5 × 107 PFU/kg resulted in no clinical or biological adverse effects. Residual TG6002 in blood, saliva, urine and feces of treated dogs was not detected by infectious titer assay nor by qPCR, ensuring the safety of the virus in the dogs and their environment. CONCLUSIONS: These results establish the good tolerability of TG6002 in healthy dogs with undetectable viral shedding after multiple injections. This study supports the initiation of further studies in canine cancer patients to evaluate the oncolytic potential of TG6002 and provides critical data for clinical development of TG6002 as a human cancer therapy.

Intermittent urethral obstruction secondary to caudal sliding of a pelvic bladder in 3 dogs.

Three Yorkshire terrier dogs (2 males and 1 female) were presented for investigation of chronic dysuria and stranguria. Physical examination was unremarkable except for a poorly filled bladder. Biological tests, urinalysis, ultrasound, and routine radiography detected no significant abnormality, except for intermittent displacement of the bladder in the pelvis. Manual voiding cysto-urethrography showed marked caudal displacement of the bladder without perineal hernia and revealed intermittent, dynamic urethral obstruction. Obstructive kinking of the membranous urethra was observed in male dogs, and the marked caudal displacement of the bladder in the female dog was suspected to induce similar urethral obstruction, although this was not clearly visualized because of the absence of contrast filling of the obstructed urethra. All dogs showed resolution of the clinical signs following cystopexy. Key clinical message: This report documents the diagnostic value of manual voiding cysto-urethrography for the investigation of dynamic voiding disorders, especially in dogs with a pelvic bladder.

Obstruction urétrale intermittente secondaire au glissement caudal d'une vessie pelvienne chez trois chiens. Trois chiens de race Yorkshire (2 mâles et 1 femelle) furent présentés pour un problème de dysurie chronique et de strangurie. L'examen physique ne révéla rien d'anormal sauf une vessie pauvrement remplie. Des tests biologiques, une analyse d'urine, une échographie et des radiographies de routine ne détectèrent aucune anormalité, sauf pour le déplacement intermittent de la vessie dans le pelvis. Une cysto-urétrographie avec vidange manuelle a montré un déplacement caudal marqué de la vessie sans hernie périnéale et a révélé une obstruction urétrale dynamique et intermittente. Une plicature obstructive de l'urètre membraneuse fut observée chez les chiens mâles, et le déplacement caudal marqué de la vessie chez la chienne fut soupçonné d'induire une obstruction urétrale similaire, bien que ceci n'était pas clairement visualisé étant donné l'absence de remplissage par le milieu de contraste de l'urètre obstruée. La résolution des signes cliniques fut observée chez tous les chiens suite à la cystopexie.Message clinique important :Ce rapport documente la valeur diagnostique d'une cysto-urétrographie avec vidange manuelle pour l'étude de désordres de vidange dynamiques, spécialement chez les chiens avec une vessie pelvienne.(Traduit par Dr Serge Messier).

Bilateral Pyelonephritis in a Cat with Multiple Urinary Malformations Including Ureteral Pseudodiverticulosis.

Ureteral pseudodiverticulosis is an unusual acquired abnormality in humans and dogs. This report describes the first feline case of ureteral pseudodiverticulosis, associated with right retrocaval ureter and malposition of the uretero-vesical junctions, in the context of pyelonephritis. The coexistence of pseudodiverticulosis with other urinary abnormalities suggested that this lesion should be considered in other patients with urinary pathology.

Is arginase a potential drug target in tobacco-induced pulmonary endothelial dysfunction?

BACKGROUND: Tobacco-induced pulmonary vascular disease is partly driven by endothelial dysfunction. The bioavailability of the potent vasodilator nitric oxide (NO) depends on competition between NO synthase-3 (NOS3) and arginases for their common substrate (L-arginine). We tested the hypothesis whereby tobacco smoking impairs pulmonary endothelial function via upregulation of the arginase pathway. METHODS: Endothelium-dependent vasodilation in response to acetylcholine (Ach) was compared ex vivo for pulmonary vascular rings from 29 smokers and 10 never-smokers. The results were expressed as a percentage of the contraction with phenylephrine. We tested the effects of L-arginine supplementation, arginase inhibition (by N(omega)-hydroxy-nor-l-arginine, NorNOHA) and NOS3 induction (by genistein) on vasodilation. Protein levels of NOS3 and arginases I and II in the pulmonary arteries were quantified by Western blotting. RESULTS: Overall, vasodilation was impaired in smokers (relative to controls; p < 0.01). Eleven of the 29 smokers (the ED(+) subgroup) displayed endothelial dysfunction (defined as the absence of a relaxant response to Ach), whereas 18 (the ED(-) subgroup) had normal vasodilation. The mean responses to 10(-4) M Ach were -23 ± 10% and 31 ± 4% in the ED(+) and ED(-) subgroups, respectively (p < 0.01). Supplementation with L- arginine improved endothelial function in the ED(+) subgroup (-4 ± 10% vs. -32 ± 10% in the presence and absence of L- arginine, respectively; p = 0.006), as did arginase inhibition (18 ± 9% vs. -1 ± 9%, respectively; p = 0.0002). Arginase I protein was overexpressed in ED(+) samples, whereas ED(+) and ED(-) samples did not differ significantly in terms of NOS3 expression. Treatment with genistein did not significantly improve endothelial function in ED(+) samples. CONCLUSION: Overexpression and elevated activity of arginase I are involved in tobacco-induced pulmonary endothelial dysfunction.

Usefulness of serum amyloid A for the diagnosis of pyelonephritis in cats: A prospective evaluation.

BACKGROUND: The diagnosis of pyelonephritis in cats is challenging and development of a noninvasive and accurate biomarker is needed. HYPOTHESES: Serum amyloid A (SAA) is increased in cats with pyelonephritis, but not in cats with other urinary tract diseases. ANIMALS: A cohort of 125 cats (149 observations). METHODS: This was a prospective study. Group 1 included cats with a diagnosis of pyelonephritis either confirmed by bacterial culture of pelvic urine (Group 1a) or presumed (1b). Group 2 included cats for which pyelonephritis was ruled out (with certainty: Group 2a or judged unlikely: Group 2b). SAA concentration was compared between groups, and accuracy of SAA for the diagnosis of pyelonephritis was calculated using a Receiver Operating Characteristic (ROC) curve analysis. RESULTS: Median SAA concentration was significantly higher in Group 1a (86.8 mg/L [73.3; 161.5]; n = 8) than in Group 2a (4 mg/L [1.8; 5.6], n = 19; P < .001) and in Group 2b (5.4 mg/L [3.1; 9.7], n = 113; P < .001). It was also significantly higher in Group 1b (98.8 mg/L [83.1; 147.3]; n = 9) than in Group 2b (P < .001) and Group 2a (P < .001). Optimal diagnostic cut-off for SAA concentration was 51.3 mg/L. yielding a sensitivity of 88% (95% confidence interval: [64%; 99%]) and a specificity of 94% (95% confidence interval: [88%; 97%]). CONCLUSIONS AND CLINICAL IMPORTANCE: Measurement of SAA could be used to rule out pyelonephritis in the case of low suspicion of the disease. Increased SAA concentration is suggestive of pyelonephritis despite a lack of specificity.

A Case of Urinary Bladder Malakoplakia in a Young French Bulldog: Diagnostic and Therapeutic Issues.

A 3-month-old female French Bulldog presented with hematuria, severe pollakiuria, and urinary incontinence lasting for 1.5 months. Broad-spectrum empirical antibiotic therapy and nonsteroidal anti-inflammatory drugs were initiated by the referring veterinarian. Due to a lack of improvement, the dog was referred. At referral examination, urinary clinical signs persisted (hematuria, severe pollakiuria) and a firm bladder was noted. Abdominal ultrasonography revealed severe, diffuse bladder wall thickening with a significant reduction in the bladder lumen. Urinary tract endoscopy showed whitish exophytic proliferations throughout the entire bladder wall. Histological bladder wall analysis led to a diagnosis of bladder malakoplakia. Prolonged antibiotic therapy with fluoroquinolones was prescribed and resulted in clinical remission despite persistent bacteria in the bladder wall. This report describes a case of successfully medically managed bladder malakoplakia, a very rare condition in veterinary medicine, well documented in humans.

Oncolytic virotherapy with intratumoral injection of vaccinia virus TG6002 and 5-fluorocytosine administration in dogs with malignant tumors.

TG6002 is an oncolytic vaccinia virus expressing FCU1 protein, which converts 5-fluorocytosine into 5-fluorouracil. The study objectives were to assess tolerance, viral replication, 5-fluorouracil synthesis, and tumor microenvironment modifications to treatment in dogs with spontaneous malignant tumors. Thirteen dogs received one to three weekly intratumoral injections of TG6002 and 5-fluorocytosine. The viral genome was assessed in blood and tumor biopsies by qPCR. 5-Fluorouracil concentrations were measured in serum and tumor biopsies by liquid chromatography or high-resolution mass spectrometry. Histological and immunohistochemical analyses were performed. The viral genome was detected in blood (7/13) and tumor biopsies (4/11). Viral replication was suspected in 6/13 dogs. The median intratumoral concentration of 5-fluorouracil was 314 pg/mg. 5-Fluorouracil was not detected in the blood. An increase in necrosis (6/9) and a downregulation of intratumoral regulatory T lymphocytes (6/6) were observed. Viral replication, 5-fluorouracil synthesis, and tumor microenvironment changes were more frequently observed with higher TG6002 doses. This study confirmed the replicative properties, targeted chemotherapy synthesis, and reversion of the immunosuppressive tumor microenvironment in dogs with spontaneous malignant tumors treated with TG6002 and 5-fluorocytosine.

Alendronate treatment in cats with persistent ionized hypercalcemia: A retrospective cohort study of 20 cases.

BACKGROUND: Limited information is available concerning treatment of ionized hypercalcemia in cats. HYPOTHESIS/OBJECTIVES: Describe clinical findings in a cohort of cats with persistent ionized hypercalcemia and evaluate long-term tolerance and efficacy of alendronate in these patients. ANIMALS: Twenty cats with persistent ionized hypercalcemia of undetermined origin, presented for routine or referral consultation at the teaching hospital of Maisons-Alfort (France). METHODS: Medical records were retrospectively reviewed. Cats were divided into Group 1 (cats that received alendronate as well as other treatments, n = 11) and Group 2 (cats that did not receive alendronate, n = 9). Survival analysis (Kaplan-Meier method, log-rank test, and Cox proportional hazard models) was conducted to compare time to selected outcomes. RESULTS: Azotemia was present in 15 cats (75%). Alendronate treatment was administered and well tolerated during the entire follow-up period (median, 9.5 months; interquartile range [IQR], 6.3; 27) in all cats from Group 1, except in 1 cat that developed severe hypophosphatemia, prompting treatment discontinuation. Univariate analysis determined that alendronate treatment was significantly associated with shorter time to reach a 15% decrease in ionized calcium concentration (iCa) from baseline during follow-up (119 days vs median not reached, P = .02). This association was no longer significant after adjustment for age and initial iCa. CONCLUSIONS AND CLINICAL IMPORTANCE: Alendronate overall was well tolerated with chronic use in this cohort, and can be considered a treatment option for persistent ionized hypercalcemia in cats.

Comparison of C-reactive protein concentrations in dogs with Bordetella bronchiseptica infection and aspiration bronchopneumonia.

BACKGROUND: C-reactive protein (CRP) is a well-known acute-phase protein in dogs that may discriminate bacterial bronchopneumonia from other pulmonary conditions. Bronchopneumonia caused by Bordetella bronchiseptica (Bb) is common but the associated increase in CRP concentration in naturally infected dogs has not been fully explored. OBJECTIVE: To compare CRP concentrations of dogs with Bb infection, with or without radiographic pulmonary lesions, to dogs with aspiration bronchopneumonia (ABP). ANIMALS: Sixteen dogs with Bb infection and 36 dogs with ABP. METHODS: Retrospective study. C-reactive protein concentrations and thoracic radiographs were available for each dog. RESULTS: Eleven dogs with Bb infection had alveolar lesions. In all dogs, CRP concentration was mildly increased (14-38 mg/L). In the 5 dogs without alveolar lesions, CRP concentration was within the reference range in all but 1 dog, in which it was slightly increased. Median CRP concentration was significantly higher in dogs with alveolar lesions (20 mg/L) compared with dogs without alveolar lesions (5 mg/L; p < .002). In dogs with Bb infection, median duration of clinical signs was not different between dogs with normal CRP concentration and dogs with increased concentration. In dogs with Bb infection either with or without alveolar lessions, median CRP concentration was significantly lower (20 mg/L) than in dogs with ABP (118 mg/L; p < .001). CONCLUSIONS AND CLINICAL IMPORTANCE: In contrast to dogs with APB, CRP was not a good marker for the diagnosis of dogs suspected to have bordetellosis. Confirmation of Bb infection still requires lower airway sampling.

Safety, biodistribution and viral shedding of oncolytic vaccinia virus TG6002 administered intravenously in healthy beagle dogs.

Oncolytic virotherapy is an emerging strategy that uses replication-competent viruses to kill tumor cells. We have reported the oncolytic effects of TG6002, a recombinant oncolytic vaccinia virus, in preclinical human xenograft models and canine tumor explants. To assess the safety, biodistribution and shedding of TG6002 administered by the intravenous route, we conducted a study in immune-competent healthy dogs. Three dogs each received a single intravenous injection of TG6002 at 105 PFU/kg, 106 PFU/kg or 107 PFU/kg, and one dog received three intravenous injections at 107 PFU/kg. The injections were well tolerated without any clinical, hematological or biochemical adverse events. Viral genomes were only detected in blood at the earliest sampling time point of one-hour post-injection at 107 PFU/kg. Post mortem analyses at day 35 allowed detection of viral DNA in the spleen of the dog which received three injections at 107 PFU/kg. Viral genomes were not detected in the urine, saliva or feces of any dogs. Seven days after the injections, a dose-dependent antibody mediated immune response was identified. In conclusion, intravenous administration of TG6002 shows a good safety profile, supporting the initiation of clinical trials in canine cancer patients as well as further development as a human cancer therapy.

Preclinical Evaluation of the Oncolytic Vaccinia Virus TG6002 by Translational Research on Canine Breast Cancer.

Oncolytic virotherapy is a promising therapeutic approach for the treatment of cancer. TG6002 is a recombinant oncolytic vaccinia virus deleted in the thymidine kinase and ribonucleotide reductase genes and armed with the suicide gene FCU1, which encodes a bifunctional chimeric protein that efficiently catalyzes the direct conversion of the nontoxic 5-fluorocytosine into the toxic metabolite 5-fluorouracil. In translational research, canine tumors and especially mammary cancers are relevant surrogates for human cancers and can be used as preclinical models. Here, we report that TG6002 is able to replicate in canine tumor cell lines and is oncolytic in such cells cultured in 2D or 3D as well as canine mammary tumor explants. Furthermore, intratumoral injections of TG6002 lead to inhibition of the proliferation of canine tumor cells grafted into mice. 5-fluorocytosine treatment of mice significantly improves the anti-tumoral activity of TG6002 infection, a finding that can be correlated with its conversion into 5-fluorouracil within infected fresh canine tumor biopsies. In conclusion, our study suggests that TG6002 associated with 5-fluorocytosine is a promising therapy for human and canine cancers.

Frequency of bacteriuria in dogs with chronic kidney disease: A retrospective study of 201 cases.

BACKGROUND: Studies have shown an increased prevalence of positive urine culture (PUC) in cats with chronic kidney disease (CKD); no information is available in dogs. OBJECTIVES: To document the PUC frequency in a cohort of dogs with CKD, determine risk factors for PUC, and identify associations between clinicopathologic data and PUC. ANIMALS: Two hundred one client-owned dogs with CKD. METHODS: Retrospective, observational study. Dogs recruited from 2 veterinary teaching hospitals were included if they were diagnosed with CKD and had a culture performed on urine collected by cystocentesis. The PUC frequency was calculated, multivariate analysis was performed to identify risk factors, and associations with clinicopathologic data were investigated. RESULTS: Sixty-five dogs (32%) with CKD had PUC, including 8 (28%) in International Renal Interest Society (IRIS) stage 1; only 8% showed signs of a urinary tract infection. Escherichia coli was the most common isolate (67%). A PUC was more likely in females (odds ratio [OR], 3.22; 95% confidence interval [CI], 1.67-6.37; P < .001) than males and in dogs with isosthenuria (OR, 2.48; 95% CI, 1.24-5.03; P = .01) than in dogs with urine-specific gravity 1.013-1.024. A positive leukocyte esterase test and microorganisms found by urine sediment analysis were significantly associated with PUC (both P < .001). CONCLUSIONS AND CLINICAL IMPORTANCE: Dogs with CKD, even IRIS stage 1, have a high frequency of PUC and most cases are asymptomatic. A urine culture could be considered in the routine evaluation of dogs with CKD, but the clinical relevance of a PUC remains unknown and needs further evaluation.

Development and validation of a novel clinical scoring system for short-term prediction of death in dogs with acute pancreatitis.

BACKGROUND: Acute pancreatitis (AP) is associated with a high death rate in dogs, but accurate predictors of early death are still lacking. OBJECTIVES: To develop a scoring system for prediction of short-term case fatality in dogs with AP. ANIMALS: One hundred sixty-nine dogs with AP including 138 dogs in the training cohort and 31 dogs in the validation cohort. METHODS: Multicenter, retrospective cohort study. Survival analysis was used to assess the associations with short-term death (within 30 days after admission). Independent predictors of death were identified by a stepwise selection method and used for the score calculation. RESULTS: Death rate within 30 days after admission was 33% in the training cohort. Four independent risk factors for short-term death were identified in the training cohort: presence of systemic inflammatory response syndrome, coagulation disorders, increased creatinine and ionized hypocalcemia. Canine Acute Pancreatitis Severity (CAPS) score was developed to predict short-term death, integrating these 4 factors in a weighted way. A simplified version of CAPS score (sCAPS) including respiratory rate instead of SIRS was also assessed. The area under the receiver-operating characteristic curve (AUC) of CAPS and sCAPS scores was 0.92 in the training cohort with an optimal cutoff of 11 (sensitivity, 89%; specificity, 90%) and 6 (sensitivity, 96%; specificity, 77%), respectively. CAPS and sCAPS score were validated in the validation cohort with respective AUC of 0.91 and 0.96. CONCLUSIONS AND CLINICAL IMPORTANCE: We propose 2 scoring systems that allow early and accurate prediction of short-term death in dogs with AP.

Indwelling double pigtail ureteral stent combined or not with surgery for feline ureterolithiasis: complications and outcome in 15 cases.

Ureteral obstruction secondary to ureterolithiasis in cats is a challenging situation. Ureteral stenting has recently been introduced to prevent complications that often occurred after ureterotomy or other invasive surgeries. The purpose of this study is to describe the stenting technique and perioperative difficulties, as well as long-term outcome and complications with ureteral stenting in 12 cats with ureteroliths. Fifteen 2.5 Fr soft double pigtail multi-fenestrated ureteral stents were placed in an anterograde fashion under open surgical approaches and with fluoroscopic guidance in 12 cats. Nine cats received a unilateral stent and three received bilateral stents. Ureterotomy or ureteral resection and end-to-end anastomosis were performed in three and four cases, respectively. In six cats, papillotomy was performed to facilitate dilatator and stent placement. All cats recovered well from the surgical procedure, except one cat, which died during the anaesthesia recovery period. Postoperative complications included dysuria (three cases, diagnosed at 15 days, 1 month and 3 months, respectively), urinary tract infection (one case, 1 month after surgery), stent migration requiring stent replacement (one case, 19 months after surgery) and stent obstruction requiring stent removal (three cases with previously end-to-end anastomosis between 2 and 8 months after surgery). Nine cats (75%) were alive at a mean follow-up of 453 ± 194 (123-720) days. The median survival time was >415 days. Stent placement appeared to be a valuable and safe option for treating ureteral obstruction in cats. However, periodic and long-term monitoring of stents is warranted.

Azotemia in cats with feline hypertrophic cardiomyopathy: prevalence and relationships with echocardiographic variables.

OBJECTIVES: The prevalence of renal azotemia in cats with acquired heart disease is not well documented. The aims of this study were therefore (1) to determine the prevalence of azotemia within a hospital population of cats with hypertrophic cardiomyopathy (HCM), and (2) to evaluate the relationship between echocardiographic variables and plasma urea and creatinine. ANIMALS, MATERIALS AND METHODS: 134 client-owned cats were retrospectively studied including 102 cats with HCM and 32 control cats. A complete physical examination, electrocardiography, systolic arterial blood pressure measurement, thoracic radiographs, and echocardiography were performed. Plasma creatinine and urea were determined in all cats. The animal was considered azotemic if plasma creatinine was >1.8 mg/dL and/or urea >65 mg/dL (i.e. BUN> 30 mg/dL). RESULTS: The prevalence of azotemia was lower in control cats (25.0%) than in cats with HCM (58.8%) (P=0.003). No significant differences in plasma urea and creatinine were observed between the HCM and control cats. There was no effect of plasma creatinine and urea on conventional echocardiographic variables in cats with HCM. CONCLUSIONS: Azotemia is a frequent finding in cats with HCM but is not dependent on echocardiographic variables.

Impaired apoptosis of pulmonary endothelial cells is associated with intimal proliferation and irreversibility of pulmonary hypertension in congenital heart disease.

OBJECTIVES: This study sought to assess the cellular and histologic basis of irreversible pulmonary hypertension (PHT) in the clinical setting of congenital heart disease (CHD). BACKGROUND: Although many children with CHD develop pulmonary vascular disease, it is unclear why this complication is reversible after complete repair in some cases but irreversible in others. Because failure of endothelial cell apoptosis might lead to intimal proliferation and lack of reversibility of PHT, we investigated this and other key markers of vasoactivity and angiogenesis in subjects with PHT and CHD. METHODS: We assessed antiapoptotic and proapoptotic markers in vascular and perivascular cells in lung biopsy samples from 18 patients with CHD, 7 with reversible and 11 with irreversible PHT, and 6 control patients. Immunostaining for endothelial nitric oxide synthase, vascular endothelial growth factor, and CD34 (markers of vasoactivity and neoangiogenesis) was also performed. RESULTS: The antiapoptotic protein Bcl-2 was highly expressed by pulmonary endothelial cells in all cases of irreversible PHT but in no cases of reversible PHT, nor in control patients (p < 0.001). Intimal proliferation was present in 10 of 11 irreversible PHT cases, but never observed in reversible PHT (p < 0.001). Similarly, perivascular inflammatory T-cells expressed more antiapoptotic proteins in irreversible PHT (p < 0.01). Irreversible PHT cases were also more likely to show compensatory upregulation of vascular endothelial growth factor and new small vessel formation at the sites of native vessel stenosis or occlusion (p < 0.001). CONCLUSIONS: Irreversible PHT is strongly associated with impaired endothelial cell apoptosis and antiapoptotic signaling from perivascular inflammatory cells. These changes are associated with intimal proliferation and vessel narrowing, and thereby may contribute to clinical outcomes associated with pulmonary hypertension.

Interaction of KATP channels and endothelin-1 in lambs with persistent pulmonary hypertension of the newborn.

Persistent pulmonary hypertension of the newborn is a life-threatening condition in which half of infants fail to respond to inhaled nitric oxide. Development of new therapeutic pathways is crucial. The adenosine triphosphate (ATP)-sensitive potassium channels (K(ATP)) may be important in this condition. Concentration-response curves to the K(ATP) channel opener (SR47063) were performed in isolated pulmonary arterial rings from normal newborn lambs (n = 8) and pulmonary hypertensive lambs (n = 7) induced by intrauterine ductus arteriosus ligation. The effect of endothelin (ET) receptor antagonists was analyzed. Expression in the lung of the subunit Kir 6.1 of the K(ATP) channel and of ET were analyzed using Western blot and immunohistochemistry. Relaxation to SR47063 was increased in ligated animals compared with the control group. Endothelium removal enhanced this response in ligated animals (p < 0.01). The inhibitory effect of the endothelium was reversed by the Endothelin-A receptor (ET-A) antagonist BQ 123 (p < 0.01). Kir 6.1 expression was not different between groups and that of endothelin-1 (ET-1) was increased threefold in ligated animals (p = 0.007). In pulmonary hypertensive lambs, vasodilation to K(ATP) channel openers was enhanced compared with controls and further potentiated by ET-A blockade. These data might lead to new therapeutic strategies in infants with pulmonary hypertension.

Developmental expression of vasoactive and growth factors in human lung. Role in pulmonary vascular resistance adaptation at birth.

The factors that mediate the postnatal fall in pulmonary vascular resistance, which is crucial for normal gas exchange, are not fully understood. The endothelium has been implicated in this phenomenon, through the release of vasorelaxant factors such as nitric oxide (NO). Human pulmonary expression of endothelial NO synthase increases up to 31 wk of gestation, together with vascular endothelial growth factor (VEGF), and both factors potently mediate pulmonary angiogenesis and vasorelaxation. During the perinatal period, when pulmonary vasodilatation is maximal, endothelial NO synthase and VEGF are weakly expressed. This raises the involvement of vasorelaxant factors other than NO at birth. One candidate is endothelial-derived hyperpolarizing factor, which induces smooth muscle cell hyperpolarization by activating K(ATP) channels. The marked vasorelaxation induced by activation of these channels in newborn animals, and their strong perinatal expression in the human lung, suggest their involvement during this phase. Another candidate is endothelin (ET)-1, together with its receptors ET-A and ET-B. ET-A receptors are located exclusively on smooth muscle cells and mediate vasoconstriction, whereas ET-B receptors mediate vasoconstriction when located on smooth muscle cells and vasodilatation when located on endothelial cells. ET-B receptors, which are strongly expressed in the human fetal lung both at the end of gestation and after birth, may be involved in perinatal pulmonary vasodilatation. Thus, in human fetal lung, K(ATP) channels and ET-B receptors could be important in mediating the perinatal pulmonary vasodilatation crucial for adapting the pulmonary circulation to extrauterine life.