Christopher A. Adin

Embryonic Stem Cells Proliferate and Differentiate when Seeded into Kidney Scaffolds

The scarcity of transplant allografts for diseased organs has prompted efforts at tissue regeneration using seeded scaffolds, an approach hampered by the enormity of cell types and complex architectures. Our goal was to decellularize intact organs in a manner that retained the matrix signal for differentiating pluripotent cells. We decellularized intact rat kidneys in a manner that preserved the intricate architecture and seeded them with pluripotent murine embryonic stem cells antegrade through the artery or retrograde through the ureter. Primitive precursor cells populated and proliferated within the glomerular, vascular, and tubular structures. Cells lost their embryonic appearance and expressed immunohistochemical markers for differentiation. Cells not in contact with the basement membrane matrix became apoptotic, thereby forming lumens. These observations suggest that the extracellular matrix can direct regeneration of the kidney, and studies using seeded scaffolds may help define differentiation pathways.

Cisplatin: a review of toxicities and therapeutic applications.

Cisplatin is a platinum chemotherapeutic used in a variety of malignancies. The antineoplastic activity occurs from DNA cross-links and adducts, in addition to the generation of superoxide radicals. Nephrotoxicity is the most well-known and potentially most clinically significant toxicity. Unfortunately, the mechanism for cisplatin nephrotoxicity has not been completely elucidated; however, many theories have been developed. Other toxicities include gastrointestinal, myelosuppression, ototoxicity and neurotoxicity. Saline diuresis is currently the most accepted way to prevent cisplatin nephrotoxicity. Research has focused on pharmaceuticals and enzyme/molecular alterations as alternatives to long-term diuresis. No agents have currently been identified that can protect from all toxicities. Cisplatin has shown activity against osteosarcoma, transitional cell carcinoma, squamous cell carcinoma (SCC), melanoma, mesothelioma, carcinomatosis and germinal cell tumours in the dog. In the cat, cisplatin cannot be utilized because of fulminant pulmonary oedema that occurs at standard doses. Intralesional cisplatin has been utilized in horses for the treatment of SCC and sarcoids.

Complications of ovariohysterectomy and orchiectomy in companion animals.

Complications following elective spay or neuter procedures are particularly feared by new graduates. However, even the most experienced surgeons may encounter surgical or postoperative complications. At best, complications associated with elective procedures can harm the doctor-client relationship. At worst, these can present legal and financial problems. Veterinary surgeons should be aware of the potential complications associated with elective sterilization, these should be communicated to the client, and there should be a clear plan for action when a complication occurs. This article reviews the reported complications encountered in elective sterilization surgery in companion animals, with a special focus on early detection and prevention.

Intraperitoneal bilirubin administration decreases infarct area in a rat coronary ischemia/reperfusion model

Bilirubin was previously considered a toxin byproduct of heme catabolism. However, a mounting body of evidence suggests that at physiological doses, bilirubin is a powerful antioxidant and anti-atherosclerotic agent. Recent clinical studies have shown that human beings with genetically-induced hyperbilirubinemia (Gilbert Syndrome) are protected against coronary heart disease. The purpose of this study was to investigate whether administration of exogenous bilirubin to normal rats would convey similar protective effects in an experimental model of coronary ischemia. We hypothesized that intraperitoneal bilirubin administration 1 h before injury would decrease infarct area and preserve left ventricular (LV) systolic function when compared to non-treated rats. Coronary ischemia was induced by temporary (30 min) ligation of the left anterior descending coronary artery in control or bilirubin treated rats, followed by a 1-h period of reperfusion. LV function was estimated by measurements of fractional shortening (FS) and fractional area shortening using echocardiography. LV function decreased in both experimental groups after ischemia and reperfusion, although in bilirubin-treated rats FS was less depressed during the period of ischemia (18.8 vs. 25.8%, p = 0.034). Infarct size was significantly reduced in the bilirubin treated group compared to the non-treated group (13.34 vs. 25.5%, p = 0.0067). Based on the results of this study, bilirubin supplementation appears to provide significant decrease in infarct size although protective effects on LV function were noted only during the period of ischemia. This result also suggests that lipid soluble antioxidant bilirubin prevents the oxidation of cardiolipin and decreases the infarct size in the heart during ischemia.

Complications of upper urinary tract surgery in companion animals.

Due to the negative effects of urine on wound healing, the high rate of complications associated with surgical incisions in the ureter and a desire to avoid large open approaches to the abdomen, there is a strong trend in human medicine toward the use of endoscopic methods in the treatment of upper urinary tract disease. However, the small size of urogenital structures in companion animals has prevented the widespread application of endoscopy of the upper urinary tract and surgery continues to be the mainstay of treatment. Through careful decision making, veterinary surgeons now use microsurgical technique and interventional radiology to provide a high success rate. The current review will discuss complications pertaining to surgery of the kidney and ureter in companion animals, using experimental and clinical data to guide the detection and avoidance of these complications.

Long‐Term Efficacy of a Percutaneously Adjustable Hydraulic Urethral Sphincter for Treatment of Urinary Incontinence in Four Dogs

OBJECTIVE To evaluate the efficacy of a surgically placed, static hydraulic urethral sphincter (SHUS) for treatment of urethral sphincter mechanism incompetency (USMI). STUDY DESIGN Prospective study. ANIMALS Spayed female dogs (n=4) with acquired USMI. METHODS Urinary incontinence was assessed using a subjective continence score before and after implantation of an SHUS on the proximal urethra via ventral median celiotomy. Dogs were assessed for urinary continence, urinary tract infections, and implant-associated complications for 30 months. Residual incontinence was treated with percutaneous inflation of the SHUS with sterile saline solution through a biocompatible subcutaneous administration port. RESULTS At last follow-up (26-30 months after surgery), continence scores improved from a median preoperative score of 3/10 to a median postoperative score of 10. One dog developed wound drainage over the subcutaneously placed administration port but remained continent after port removal. Three occluders were percutaneously filled with additional saline (median, 0.18 mL; mean, 0.16 mL) to improve continence after surgery. CONCLUSIONS Application and adjustment of an SHUS provided sustained improvements in continence score in all dogs. CLINICAL RELEVANCE In this pilot study, 3 of 4 dogs with hydraulic urethral sphincter implantation had successful percutaneous adjustment and maintained improved continence scores for 2 years after surgery. Continence was maintained in the 4th dog even after administration port removal. Based on this pilot study, the SHUS warrants further clinical evaluation for treatment of dogs with USMI unresponsive to medical management.

Intermittent hypoxia exacerbates pancreatic β-cell dysfunction in a mouse model of diabetes mellitus.

STUDY OBJECTIVES The effects of intermittent hypoxia (IH) on pancreatic function in the presence of diabetes and the underlying mechanisms are unclear. We hypothesized that IH would exacerbate pancreatic β-cell dysfunction and alter the fatty acids in the male Tallyho/JngJ (TH) mouse, a rodent model of type 2 diabetes. DESIGN TH mice were exposed for 14 d to either 8 h of IH or intermittent air (IA), followed by an intraperitoneal glucose tolerance test (IPGTT) and tissue harvest. The effect of IH on insulin release was determined by using a β3-adrenergic receptor (AR) agonist. MEASUREMENTS AND RESULTS During IH, pancreatic tissue pO2 decreased from 20.4 ± 0.9 to 5.7 ± 2.6 mm Hg, as determined by electron paramagnetic resonance oximetry. TH mice exposed to IH exhibited higher plasma glucose levels during the IPGTT (P < 0.001) while the insulin levels tended to be lower (P = 0.06). Pancreatic islets of the IH group showed an enhancement of the caspase-3 staining (P = 0.002). IH impaired the β-AR agonist-mediated insulin release (P < 0.001). IH increased the levels of the total free fatty acids and saturated fatty acids (palmitic and stearic acids), and decreased levels of the monounsaturated fatty acids in the pancreas and plasma. Ex vivo exposure of pancreatic islets to palmitic acid suppressed insulin secretion and decreased islet cell viability. CONCLUSIONS Intermittent hypoxia increases pancreatic apoptosis and exacerbates dysfunction in a polygenic rodent model of diabetes. An increase in free fatty acids and a shift in composition towards long chain saturated fatty acid species appear to mediate these effects.

Outcome after Placement of an Artificial Urethral Sphincter in 27 Dogs

Objective To evaluate the safety and efficacy of an adjustable artificial urethral sphincter (AUS) in a population of dogs with acquired or congenital urinary incontinence. Study Design Case series. Animals Dogs (n = 27) with naturally occurring urinary incontinence. Methods Medical records (January 2009–July 2011) of dogs that had AUS implantation for treatment of urinary incontinence were reviewed and owners were interviewed by telephone to assess outcome. Continence was scored using a previously established analogue scale, with 1 representing constant leakage and 10 representing complete continence. Results Twenty-four female and 3 male dogs had AUS implantation. Causes of incontinence included urethral sphincter mechanism incompetence (n = 18), continued incontinence after ectopic ureter repair (6), and pelvic bladder (3). Medical therapy was unsuccessful in 25 dogs before AUS implantation. Surgery was performed without major complications in 25 dogs; 2 developed partial urethral obstruction after 5 and 9 months. Median (interquartile range) follow-up for the other 25 dogs was 12.5 (6–19) months. Continence scores were significantly improved (P < .0001) between the preoperative period (2 [1–4]) and last follow-up (9 [8–10]). Overall, 22 owners described themselves as very satisfied, 2 as satisfied, and 3 as unsatisfied. Conclusions AUS implantation was successful in restoring continence in male and female dogs with both congenital and acquired urinary incontinence. Dogs that develop partial urethral obstruction may require AUS removal.OBJECTIVE To evaluate the safety and efficacy of an adjustable artificial urethral sphincter (AUS) in a population of dogs with acquired or congenital urinary incontinence. STUDY DESIGN Case series. ANIMALS Dogs (n = 27) with naturally occurring urinary incontinence. METHODS Medical records (January 2009-July 2011) of dogs that had AUS implantation for treatment of urinary incontinence were reviewed and owners were interviewed by telephone to assess outcome. Continence was scored using a previously established analogue scale, with 1 representing constant leakage and 10 representing complete continence. RESULTS Twenty-four female and 3 male dogs had AUS implantation. Causes of incontinence included urethral sphincter mechanism incompetence (n = 18), continued incontinence after ectopic ureter repair (6), and pelvic bladder (3). Medical therapy was unsuccessful in 25 dogs before AUS implantation. Surgery was performed without major complications in 25 dogs; 2 developed partial urethral obstruction after 5 and 9 months. Median (interquartile range) follow-up for the other 25 dogs was 12.5 (6-19) months. Continence scores were significantly improved (P < .0001) between the preoperative period (2 [1-4]) and last follow-up (9 [8-10]). Overall, 22 owners described themselves as very satisfied, 2 as satisfied, and 3 as unsatisfied. CONCLUSIONS AUS implantation was successful in restoring continence in male and female dogs with both congenital and acquired urinary incontinence. Dogs that develop partial urethral obstruction may require AUS removal.

Pharmacokinetics and pharmacodynamics of the glucagon-like peptide-1 analog liraglutide in healthy cats

Glucagon-like peptide-1 (GLP-1) is an intestinal hormone that induces glucose-dependent stimulation of insulin secretion while suppressing glucagon secretion. Glucagon-like peptide-1 also increases beta cell mass and satiation while decelerating gastric emptying. Liraglutide is a fatty-acid derivative of GLP-1 with a protracted pharmacokinetic profile that is used in people for treatment of type II diabetes mellitus and obesity. The aim of this study was to determine the pharmacokinetics and pharmacodynamics of liraglutide in healthy cats. Hyperglycemic clamps were performed on days 0 (HGC) and 14 (LgHGC) in 7 healthy cats. Liraglutide was administered subcutaneously (0.6 mg/cat) once daily on days 8 through 14. Compared with the HGC (mean ± standard deviation; 455.5 ± 115.8 ng/L), insulin concentrations during LgHGC were increased (760.8 ± 350.7 ng/L; P = 0.0022), glucagon concentrations decreased (0.66 ± 0.4 pmol/L during HGC vs 0.5 ± 0.4 pmol/L during LgHGC; P = 0.0089), and there was a trend toward an increased total glucose infused (median [range] = 1.61 (1.11-2.54) g/kg and 2.25 (1.64-3.10) g/kg, respectively; P = 0.087). Appetite reduction and decreased body weight (9% ± 3%; P = 0.006) were observed in all cats. Liraglutide has similar effects and pharmacokinetics profile in cats to those reported in people. With a half-life of approximately 12 h, once daily dosing might be feasible; however, significant effects on appetite and weight loss may necessitate dosage or dosing frequency reductions. Further investigation of liraglutide in diabetic cats and overweight cats is warranted.

Pharmacology of the glucagon-like peptide-1 analog exenatide extended-release in healthy cats

Exenatide extended-release (ER) is a microencapsulated formulation of the glucagon-like peptide 1-receptor agonist exenatide. It has a protracted pharmacokinetic profile that allows a once-weekly injection with comparable efficacy to insulin with an improved safety profile in type II diabetic people. Here, we studied the pharmacology of exenatide ER in 6 healthy cats. A single subcutaneous injection of exenatide ER (0.13 mg/kg) was administered on day 0. Exenatide concentrations were measured for 12 wk. A hyperglycemic clamp (target = 225 mg/dL) was performed on days -7 (clamp I) and 21 (clamp II) with measurements of insulin and glucagon concentrations. Glucose tolerance was defined as the amount of glucose required to maintain hyperglycemia during the clamp. Continuous glucose monitoring was performed on weeks 0, 2, and 6 after injection. Plasma concentrations of exenatide peaked at 1 h and 4 wk after injection. Comparing clamp I with clamp II, fasting blood glucose decreased (mean ± standard deviation = -11 ± 8 mg/dL, P = 0.02), glucose tolerance improved (median [range] +33% [4%-138%], P = 0.04), insulin concentrations increased (+36.5% [-9.9% to 274.1%], P = 0.02), and glucagon concentrations decreased (-4.7% [0%-12.1%], P = 0.005). Compared with preinjection values on continuous glucose monitoring, glucose concentrations decreased and the frequency of readings <50 mg/dL increased at 2 and 6 wk after injection of exenatide ER. This did not correspond to clinical hypoglycemia. No other side effects were observed throughout the study. Exenatide ER was safe and effective in improving glucose tolerance 3 wk after a single injection. Further evaluation is needed to determine its safety, efficacy, and duration of action in diabetic cats.