Decreased LPS-induced lung injury in pigs treated with a lung surfactant protein A-derived nonapeptide that inhibits peroxiredoxin 6 activity and subsequent NOX1,2 activation.

This study addressed the efficacy of a liposome-encapsulated nine amino acid peptide [peroxiredoxin 6 PLA2 inhibitory peptide-2 (PIP-2)] for the prevention or treatment of acute lung injury (ALI) +/- sepsis. PIP-2 inhibits the PLA2 activity of peroxiredoxin 6 (Prdx6), thereby preventing rac release and activation of NADPH oxidases (NOXes), types 1 and 2. Female Yorkshire pigs were infused intravenously with lipopolysaccharide (LPS) + liposomes (untreated) or LPS + PIP-2 encapsulated in liposomes (treated). Pigs were mechanically ventilated and continuously monitored; they were euthanized after 8 h or earlier if preestablished humane endpoints were reached. Control pigs (mechanical ventilation, no LPS) were essentially unchanged over the 8 h study. LPS administration resulted in systemic inflammation with manifestations of clinical sepsis-like syndrome, decreased lung compliance, and a marked decrease in the arterial Po2 with vascular instability leading to early euthanasia of 50% of untreated animals. PIP-2 treatment significantly reduced the requirement for supportive vasopressors and the manifestations of lung injury so that only 25% of animals required early euthanasia. Bronchoalveolar lavage fluid from PIP-2-treated versus untreated pigs showed markedly lower levels of total protein, cytokines (TNF-α, IL-6, IL-1ß), and myeloperoxidase. Thus, the porcine LPS-induced sepsis-like model was associated with moderate to severe lung pathophysiology compatible with ALI, whereas treatment with PIP-2 markedly decreased lung injury, cardiovascular instability, and early euthanasia. These results indicate that inhibition of reactive oxygen species (ROS) production via NOX1/2 has a beneficial effect in treating pigs with LPS-induced ALI plus or minus a sepsis-like syndrome, suggesting a potential role for PIP-2 in the treatment of ALI and/or sepsis in humans.NEW & NOTEWORTHY Currently available treatments that can alter lung inflammation have failed to significantly alter mortality of acute lung injury (ALI). Peroxiredoxin 6 PLA2 inhibitory peptide-2 (PIP-2) targets the liberation of reactive O2 species (ROS) that is associated with adverse cell signaling events, thereby decreasing the tissue oxidative injury that occurs early in the ALI syndrome. We propose that treatment with PIP-2 may be effective in preventing progression of early disease into its later stages with irreversible lung damage and relatively high mortality.

Morphometric analysis of the human common hepatic artery reveals a rich and accessible target for sympathetic liver denervation.

This study quantified the distribution of nerves and adjacent anatomies surrounding human common hepatic artery (CHA) as guidance for catheter based denervation. CHA collected from cadaveric human donors (n = 20) were histologically evaluated and periarterial dimensions and distributions of nerves, lymph nodes, pancreas and blood vessels quantified by digital morphometry. Nerve abundance decreased significantly with distance from the aortic ostium (P < 0.0001) and was higher in the Superior/Inferior compared to the Anterior/Posterior quadrants (P = 0.014). In each locational group, nerves were absent from the artery wall, and starting 0.5-1.0 mm from the lumen exhibited a first order dependence on radial distance, fully defined by the median distance. Median subject-averaged nerve distance to the lumen was 2.75 mm, ranging from 2.1-3.1 mm in different arterial segments and quadrants and 2.0-3.5 mm in individuals. Inter-individual variance was high, with certain individuals exhibiting 50th and 75th nerve distances of, respectively, 3.5 and 6.5 mm The pancreas rarely approached within 4 mm of the lumen proximally and 2.5 mm more distally. The data indicate that the CHA is a rich and accessible target for sympathetic denervation regardless of sex and diabetes, with efficacy and safety most optimally balanced proximally.

Pulsed Field Ablation Using a Lattice Electrode for Focal Energy Delivery: Biophysical Characterization, Lesion Durability, and Safety Evaluation.

BACKGROUND: Pulsed field ablation (PFA) is a nonthermal energy that may provide safety advantages over radiofrequency ablation (RFA). One-shot PFA catheters have been developed for pulmonary vein isolation, but they do not permit flexible lesion sets. This study investigated a novel lattice-tip catheter designed for focal RFA or PFA ablation. METHODS: The effects of PFA (biphasic, 24 amperes) were investigated in 25 swine using a lattice-tip catheter and system (Affera Inc). Step 1 (n=14) examined the feasibility to create atrial line of block and described its acute effects on the phrenic nerve and esophagus. Step 2 (n=7) examined the subacute effects of PFA on block durability, phrenic nerve, and esophagus ≥2 weeks. Step 3 compared the effects of PFA and RFA on the esophagus using a mechanical deviation model approximating the esophagus to the right atrium (n=4) and by direct ablation within its lumen (n=4). The effects of endocardial PFA and RFA on the phrenic nerve were also compared (n=10). Histological analysis was performed. RESULTS: PFA produced acute block in 100% of lines, achieved with 2.1 (1.3-3.2) applications/cm line. Histological analysis following (35 [18-37]) days showed 100% transmurality (thickness range 0.4-3.4 mm) with a lesion width of 19.4 (10.9-27.4 mm). PFA selectively affected cardiomyocytes but spared blood vessels and nervous tissue. PFA applied from the posterior atria (23 [21-25] applications) to the approximated esophagus (6 [4.5-14] mm) produced transmural lesions without esophageal injury. PFA (16.5 [15-18] applications) applied inside the esophageal lumen produced mild edema compared with RFA (13 [12-14] applications) which produced epithelial ulcerations. PFA resulted in no or transient stunning of the phrenic nerve (<5 minutes) without histological changes while RFA produced paralysis. CONCLUSIONS: PFA using a lattice-tip ablation catheter for focal ablation produced durable atrial lesions and showed lower vulnerability to esophageal or phrenic nerve damage compared with RFA.

Splenic artery denervation: target micro-anatomy, feasibility, and early preclinical experience.

This study sought to evaluate perisplenic artery nerve distribution and the feasibility of splenic artery denervation (SDN). The NEXION radiofrequency catheter was used to perform SDN in healthy and inflammatory arthritis pigs. Splenic artery anatomy, nerve distribution, and splenic norepinephrine (NEPI) levels were evaluated before and after SDN. Perisplenic artery nerves were primarily distributed within 2.5 mm of the arterial lumen and were largely sympathetic on the basis of tyrosine hydroxylase expression. The pancreas, tended to be circumferentially positioned around the proximal splenic artery, typically >2.5 mm from the lumen, ensuring that most of the nerves could be targeted without affecting this sensitive organ. The mid segment of the splenic artery was relatively free of contact with the adjacent pancreas. Splenic NEPI levels and nerve abundance followed a decreasing gradient from the proximal to distal splenic artery. SDN resulted in significant reductions in splenic NEPI levels at day 14 (60.7%, P = 0.024) in naïve pigs and day 45 (100%, P = 0.001) in inflammatory arthritis pigs. There was no significant effect of SDN on joint soft tissue injury or circulating inflammatory markers in the inflammatory arthritis model. The majority of perisplenic arterial nerves are within close proximity of the lumen and are primarily sympathetic efferent fibers. Nerves in the mid-segment may be the preferred SDN target given their proximity to the artery and paucity of periarterial off-target organs. SDN appears safe and effective at reducing splenic NEPI levels.

Suture-Based Debris Behavior in the Draining Lymph Nodes of a Porcine Knee: A Study of Silicone, Polyethylene and Carbon.

PURPOSE: To determine whether debris from a silicone core suture has an observable intra-articular or extra-articular impact or can be shown to migrate into the lymphatic system. METHODS: Using a porcine stifle joint model, 2 study groups were created: 1 group used silicone-suture particles created by rupturing hand-tied knots of a nonabsorbable suture with an outer sheath of ultrahigh molecular-weight polyethylene, an inner polyester sheath and a medical-grade silicone/sodium chloride-filled core. The second group used a mixture of 3 vitreous carbon particles sizes. Twelve Yorkshire pigs were randomly assigned to each group. Only 1 type of study particle was used in a single animal to avoid cross-contamination. Half of the study materials were placed by arthrotomy into the joint and, after capsular closure, the remaining half were placed on the joint capsule before skin closure. Six weeks postimplantation, the stifle joints and regional lymph nodes were examined macroscopically and microscopically. The extracapsular and intra-articular tissue and the lymph nodes were examined. RESULTS: Macroscopically, none of the 12 silicone-suture particle group limbs had abnormal macroscopic observations. Of the 12 limbs in the carbon particle group, 8 demonstrated discoloration in the extracapsular, intra-articular and lymph node tissues; 6 limbs demonstrated joint discoloration (extracapsular and intra-articular). The silicone-suture particle group showed lymph node inflammation in 25% of the iliac lymph nodes and 42% of the inguinal lymph nodes but none in the popliteal lymph nodes. In the carbon particle group, 100% of the iliac lymph nodes, 75% of the inguinal lymph nodes and 8% of the popliteal nodes showed inflammation. No silicone-suture debris migration was observed microscopically. Visible carbon particle migration was present in 100% of the iliac lymph nodes and in 50% of the inguinal lymph nodes but in none (0) of the popliteal lymph nodes. The carbon particle group also showed inflammation in these areas. CONCLUSIONS: Carbon particles in the porcine knee migrated into the lymph nodes (iliac 100%; inguinal 50%, popliteal 0); gross discoloration was observed in 8 of 12 specimens. Silicone-suture particles could not be found in the lymph nodes, and no macroscopic joint damage was observed. CLINICAL RELEVANCE: The clinical use of a suture containing a silicone/salt central core is common, and the porcine lymphatic model suggests that this type of suture material does not result in clinically significant silicone particulates.

Preclinical Evaluation of Mesh Implants: The Pathologist's Perspective.

Surgical and laparoscopic implantation of mesh devices is on the rise for a variety of applications. The complexity and range of evolving mesh designs calls for consistent and detailed pathologic evaluation in determining host responses and assessing overall safety. This review addresses the components of evaluation of mesh implants in animal models, with emphasis on histologic parameters, semiquantitative scoring matrices, and morphometric analyses that have been specifically adapted to this class of implants. Necropsy assessment should include implant persistence, architecture, and associated host responses such as exudation and adhesions. Microscopic evaluation should focus on primary relevant responses such as bioresorption, integration/tissue ingrowth, neovascularization, and inflammation. Selection of the best means of processing and evaluation can be complicated, as meshes may include one or more biologic components (e.g., collagen), synthetic polymer fibers, coatings, and other molecules. The architecture of some meshes can influence tissue responses and complicate sampling, sectioning, and evaluation. Recognition of specific study objectives and knowledge of anticipated responses helps to determine the appropriate histologic or immunochemical stains, while understanding of mesh composition and anticipated persistence in tissue determines the suitability of paraffin or resin embedding, and both guide the evaluation of mesh devices in the preclinical setting.

Development of a Porcine Lymph Drainage Model to Study Particle Migration.

Background: Intra-articular wear particulate migration from the knee joint has been studied in various animal models as well as postmortem in patients who received total knee joint replacement. However, there still exists a need for a simple, yet analogous animal model for tracking the migration of wear debris from the knee joint, especially through the draining lymph nodes. Methods and Results: To fill this need, a proof-of-concept porcine model was developed for particle migration from the knee joint into the surrounding lymphatic system. Vitreous carbon particles were deposited both intra-articularly and extracapsularly in a bilateral manner to the hind limbs in pigs (n = 6). The regional/draining lymph nodes were qualitatively assessed weekly by a veterinarian by manual palpation to detect any enlargement or change in consistency when compared to the initial assessment before the surgical procedure. At 6 weeks, the draining lymph nodes were harvested and processed for histology. Microscopic evaluation showed carbon particle migration from the knee into 100% of the iliac lymph nodes, 50% of the inguinal lymph nodes, and 0% of the popliteal lymph nodes. Discussion: Overall, this study established a needed animal model for evaluating carbon particle migration to the draining lymph nodes from the knee joint.

Cystoscopic diagnosis of polypoid cystitis in two pet rabbits.

CASE DESCRIPTION AS-year-old male Dwarf rabbit and 4-year-old female Mini-Rex rabbit were evaluated because of anorexia and urine scalding of the perineum. CLINICAL FINDINGS Abdominal radiography revealed a diffuse increase in the opacity of the urinary bladder attributable to urinary sludge. In 1 rabbit, abdominal ultrasonography revealed several mass-like lesions protruding from the mucosal surface into the lumen of the urinary bladder. Rabbits were anesthetized, and cystoscopy was performed with a rigid 2.7-mm, 30° endoscope. Histologic analysis of tissue samples obtained through the cystoscope operating channel revealed findings consistent with polypoid cystitis. TREATMENT AND OUTCOME To remove the urinary sludge from each rabbit, the urinary bladder was filled with sterile saline (0.9% NaCl) solution and emptied with a gentle massage several times until the ejected fluid was transparent. Rabbits were treated with NSAIDs, antimicrobials (chosen following microbial culture of urine and antimicrobial susceptibility testing), bathing of the perineum, and a low-calcium diet. The male rabbit died of unrelated causes 18 months later; postmortem examination findings confirmed the polypoid cystitis. The female rabbit remained disease free through to last follow-up (12 months after initial evaluation). CLINICAL RELEVANCE This was the first report of polypoid cystitis in pet rabbits. Although ultrasonographic findings supported this diagnosis, a definitive diagnosis was achieved through cystoscopy and lesion biopsy. Treatments administered were intended to reduce the potential sources of irritation. Research is needed to investigate the effectiveness of the applied interventions and the association between excessive urinary calcium excretion and polyploid cystitis in rabbits.

Use of Cystoscopy to Visualize Morphological Alteration of the Liver in a Posthatchling Turtle ( Cuora trifasciata ).

A 55 g, 7 mo old Chinese three-striped box turtle ( Cuora trifasciata ) was presented with a 2 wk history of lethargy and anorexia. The owner attempted various antibiotic treatments without clinical improvement. A cystoscopic evaluation of the coelom was performed. The liver appeared dark red-to-brown presenting multifocal irregularly shaped white-to-tan and roughly round areas of discoloration on the capsular surface. An adult keeled box turtle (Pyxidea mouhotii), which died in the same facility at the same time, had similar hepatic lesions detected upon necropsy. From hepatic lesions, an antibiotic-resistant Escherichia coli was isolated. Antibiotic treatment based on sensitivity testing led to a rapid resolution of the clinical signs in the Cuora trifasciata , with gain of appetite 4 days after the first antibiotic administration. A recheck cystoscopy demonstrated macroscopic resolution of hepatic lesions. This report demonstrates, to the best of the authors' knowledge, for the first time the clinical usefulness of cystoscopy for the diagnostic evaluation of the coelom of small chelonians. This minimally invasive technique is a valuable clinical tool in the medical approach to posthatchling chelonians.

Mucus accumulation and necrosis of the ventral air pouch in a marabou stork (Leptoptilos crumeniferus) with productive rhinitis.

A captive-born marabou stork (Leptoptilos crumeniferus) was presented for swelling of the ventral air pouch of 1 month's duration. The pouch appeared fluid filled, and its distal third wall was markedly inspissated. The thickened distal portion of the pouch wall was removed surgically. During anesthesia, mucous discharge from the nares was evident and the nasal mucosa was hyperemic. Aeromonas and Proteus species were isolated from a nasal culture. Postoperative therapy that consisted of nasal flushing, antimicrobial agents, and nonsteroidal anti-inflammatory drugs was effective in managing the disease. On histologic examination, diffuse hemorrhage, necrosis, and multifocal vasculitis with moderate-to-severe heterophilic inflammation were present within sections of the ventral pouch. To our knowledge this is the first report of a mucus-filled ventral air pouch with associated pathologic changes secondary to a productive infection of the upper respiratory tract in a marabou stork. The unique communication between nasal cavities and the ventral air pouch should be considered in future cases of respiratory infection in marabou storks.

Cystoscopic sex identification of posthatchling chelonians.

OBJECTIVE: To describe a noninvasive technique for sex identification of posthatchling chelonians and to assess its safety in Hermann's tortoises (Testudo hermanni). DESIGN: Validation study and clinical trial. ANIMALS: 15 recently dead posthachling chelonians and 25 healthy posthatchling Hermann's tortoises. PROCEDURES: Cystoscopy was performed on both dead and anesthetized live chelonians. Dead chelonians ranged in body weight from 32.4 to 75.1 g (0.07 to 0.17 lb; median, 45.7 g [0.10 lb]). Dead chelonians were dissected immediately after cystoscopy, and gonads were collected for histologic examination. Urinary bladder was macroscopically evaluated in situ to assess its integrity after retrograde injection of saline (0.9% NaCl) solution. Hermann's tortoises ranged in body weight from 27.3 to 57.8 g (0.06 to 0.13 lb; median, 37.0 g [0.08 lb]). Cystoscopic examination of live tortoises was performed following induction of general anesthesia with a mixture of morphine, dexmedetomidine, and ketamine administered IM. The Pearson coefficient was used to assess the consistency between procedure time and body weight; κ statistic was used to evaluate agreement between sex identified by cystoscopy and histologic examination beyond that expected by mere chance. RESULTS: Visualization of gonads was feasible through the thin, transparent urinary bladder wall in all the animals evaluated in this study. Blinded histologic examination confirmed the results of cystoscopic gonad identification in all dead chelonians (κ = 1.0). The urinary bladder did not have evidence of macroscopic leakage or microscopic alterations of normal tissue architecture within the representative sections chosen for histologic examination. In live tortoises, median procedure time (range) was 90 (39 to 345) seconds. No significant correlations were found between procedure time and body weight. CONCLUSIONS AND CLINICAL RELEVANCE: Cystoscopy performed by means of rigid endoscopy with fluid instillation was found to be an effective method for sex identification of immature chelonians. Furthermore, no complications were observed when this procedure was performed in vivo.

Abdominal aortic aneurysm associated with systemic fungal infection in a German shepherd dog.

A 2 yr old spayed female German shepherd presented with a chief complaint of acute onset paraparesis and weight loss. At presentation, the dog was pyrexic, nonambulatory, and had generalized muscle wasting. Neurolocalization was consistent with a thoracolumbar spinal cord lesion. An abdominal ultrasound was performed and revealed a focal dilation (4 cm) of the terminal aorta with evidence of blood stasis consistent with an aortic aneurysm. The dog was euthanized shortly after admission to the hospital and a post mortem examination was performed. Fungal organisms were identified in the aortic aneurysm as well as from the thoracic vertebrae, mesenteric lymph nodes, axillary lymph nodes, spleen, kidneys, liver, lungs, and heart. Although the morphology was consistent with Candida spp., immunohistochemistry and PCR could not definitively identify the causative organism. Mycotic aortic aneurysms are a rare finding in humans and have not been previously reported in the dog. To the authors' knowledge, this is the first known report of an aortic aneurysm associated with systemic fungal infection in a dog.

Urinary bladder agenesis in an alpaca (Vicugna pacos) cria.

A 10-day-old female alpaca (Vicugna pacos) cria with a history of urinary straining and dribbling was presented for evaluation. The animal had markedly elevated blood fibrinogen (800 mg/dl), mildly elevated phosphorus (9.3 mg/dl), and minimally elevated blood urea nitrogen (38 mg/dl) concentrations. The total protein (5.0 g/dl) concentration was mildly decreased. These findings were suggestive of mild renal disease. An abdominal ultrasound revealed bilateral hydronephrosis and hydroureter, and no urinary bladder was identified. Gross postmortem examination revealed urinary bladder agenesis and bilateral hydronephrosis and hydroureter, with both ureters opening into a sinus in the caudal vagina. Histologic examination of the kidneys showed necrosuppurative pyelonephritis with pelvic dilation, and both ureters had mild lymphoplasmacytic and histiocytic inflammation.

Pacemaker implantation in a ferret (Mustela putorius furo) with third-degree atrioventricular block.

A 7.5-year-old castrated male ferret (Mustela putorius furo) was diagnosed with third-degree atrioventricular (AV) block. A monopolar epicardial pacemaker system was implanted, resulting in a regular, paced cardiac rhythm with third-degree AV block at 140 beats per minute. Over the next 2 months, the ferret developed anorexia, interstitial pneumonia, intermittent diarrhea, and hind-limb weakness and had a slow and progressive recovery. The ferret developed clinical signs of congestive heart failure 4 months after the surgery, resulting in its death 3 weeks later. Necropsy results attributed the death to cardiac failure due to extensive myocardial mineralization. To the authors' knowledge this is the first published report of surgical report of surgical pacemaker implantation in a ferret.