Gem is a protein of the Ras superfamily that plays a role in regulating voltage-gated Ca2+ channels and cytoskeletal reorganization. We now report that GTP-bound Gem interacts with the ...membrane-cytoskeleton linker protein Ezrin in its active state, and that Gem binds to active Ezrin in cells. The coexpression of Gem and Ezrin induces cell elongation accompanied by the disappearance of actin stress fibers and collapse of most focal adhesions. The same morphological effect is elicited when cells expressing Gem alone are stimulated with serum and requires the expression of ERM proteins. We show that endogenous Gem down-regulates the level of active RhoA and actin stress fibers. The effects of Gem downstream of Rho, i.e., ERM phosphorylation as well as disappearance of actin stress fibers and most focal adhesions, require the Rho-GAP partner of Gem, Gmip, a protein that is enriched in membranes under conditions in which Gem induced cell elongation. Our results suggest that Gem binds active Ezrin at the plasma membrane-cytoskeleton interface and acts via the Rho-GAP protein Gmip to down-regulate the processes dependent on the Rho pathway.
An 8-year-old castrated male Boxer and a 10-year-old spayed female Yorkshire Terrier were evaluated because of dyspnea. In both dogs, the dyspnea persisted after elongated soft palate resection.
...Laryngoscopic examination revealed caudal displacement of the epiglottis into the rima glottidis in both dogs. Excessive mobility of the epiglottis during respiration with episodic obstruction of the rima glottidis by the epiglottis was observed during fluoroscopic examination.
The epiglottis of both dogs was fixed in a horizontal plane by resection of a band of oral mucosa at the base of the epiglottis and closure of the mucosal defect with sutures. Fixation of the epiglottis resolved the dyspnea in both dogs.
Excessive mobility of the epiglottis can predispose to glottic obstruction and cause dyspnea in dogs. Fixation of the epiglottis in a horizontal plane may resolve dyspnea caused by epiglottic retroversion in dogs.
This report describes the case of an 11-year-old castrated male Shih Tzu who developed chylothorax three years following implantation of a transvenous pacemaker. Imaging demonstrated one definitive ...obstruction in the cranial vena cava and 3 additional suspected filling abnormalities within both external jugular veins, brachiocephalic veins and cranial vena cava. A thrombus was visualized in the cranial vena cava via transesophageal echocardiography. Thoracic duct ligation and cisterna chyli ablation were performed, with a resultant change in the nature of the fluid from chylous to a modified transudate. Repeat angiography and computed tomography three months later demonstrated a stenosis within the cranial vena cava. Balloon angioplasty was attempted, however it was unsuccessful in decreasing pleural effusion. Palliative thoracocentesis was continued until the patient developed a lung lobe torsion, at which time euthanasia was elected. Necropsy confirmed cranial vena caval syndrome secondary to transvenous pacemaker implantation induced fibrous proliferation within the vessel lumen.
To evaluate long-term function of vascular access ports (VAPs) implanted in the femoral vein of dogs and cats undergoing cancer treatment.
Prospective clinical study.
3 dogs and 6 cats treated via ...chemotherapy or radiation.
VAPs were surgically implanted in the left femoral vein of 3 dogs and 6 cats over a 1-year period. Injection port location was alternated to either a caudal thoracic or ilial location in each patient. Duration of VAP function, ease of infusion, and ease of aspiration through the VAPs were recorded, and associated complications were assessed at each VAP use. Client satisfaction with VAP placement was evaluated by use of a questionnaire.
Primary uses of the VAPs included blood sampling and delivering sedative or chemotherapeutic drugs. Median duration of successful infusion was 147 days (range, 60 to 370 days), and median duration of successful aspiration was 117 days (range, 10 to 271 days). The frequency of signs of VAP-related discomfort was low (7% of patient observations). Clients were satisfied with their decision to use VAPs. Complications included partial (n = 7) or complete (2) VAP occlusion, port migration (1), and presumptive infection (1).
Results suggested that VAP implantation into the femoral vein provides an acceptable means of chronic venous access in dogs and cats undergoing cancer treatment.
Right ventricular outflow tract obstruction was diagnosed by Doppler echocardiography in a young dog with a cardiac murmur, severe dyspnea, and a prominent sternal depression. Thoracic radiography ...confirmed a diagnosis of pectus excavatum involving the caudal third of the sternum. The right ventricular outflow obstruction was attributed to cardiac compression from the dorsally deviated sternum. External surgical splinting of the sternabrae, demonstrated by video in this report, was used to treat the pectus excavatum. Radiographic and Doppler echocardiographic examination 3 weeks and 4 months post-splinting documented resolution of both pectus excavatum and right ventricular outflow obstruction.
Encapsulation of insulin‐producing cells is a promising strategy for treatment of type 1 diabetes. However, engineering an encapsulation device that is both safe (i.e., no cell escape and no ...breakage) and functional (i.e., low foreign‐body response (FBR) and high mass transfer) remains a challenge. Here, a family of zwitterionic polyurethanes (ZPU) with sulfobetaine groups in the polymer backbone is developed, which are fabricated into encapsulation devices with tunable nanoporous structures via electrospinning. The ZPU encapsulation device is hydrophilic and fouling‐resistant, exhibits robust mechanical properties, and prevents cell escape while still allowing efficient mass transfer. The ZPU device also induces a much lower FBR or cellular overgrowth upon intraperitoneal implantation in C57BL/6 mice for up to 6 months compared to devices made of similar polyurethane without the zwitterionic modification. The therapeutic potential of the ZPU device is shown for islet encapsulation and diabetes correction in mice for ≈3 months is demonstrated. As a proof of concept, the scalability and retrievability of the ZPU device in pigs and dogs are further demonstrated. Collectively, these attributes make ZPU devices attractive candidates for cell encapsulation therapies.
A zwitterionic nanofibrous islet encapsulation device made of sulfobetaine‐modified polyurethane is reported. The device is mechanically robust, effective in preventing cell entrance or escape, hydrophilic with facile mass transfer, and biocompatible with low levels of fibrotic deposition in mice, dogs, and pigs. These attributes make it an attractive candidate for safe delivery of insulin‐producing cells to treat type 1 diabetes.
3 dogs (9 to 12 years old) were evaluated because of recurrent pleural effusion that was refractory to treatment of the underlying cause.
Dogs were evaluated because of cough, dyspnea, tachypnea, or ...lethargy or a combination of these clinical signs. Radiography, ultrasonography, or thoracocentesis were used to confirm the presence of pleural fluid in each dog. A neoplastic cause of pleural effusion was confirmed in 2 dogs. In 1 dog, fasciitis of the mediastinum and the left parietal pleura was diagnosed, with no evidence of neoplasia.
Each dog was anesthestized, and thoracotomy was performed with manual perforation of the mediastinum. Permanent, subcutaneously placed vascular access ports were attached to intrathoracic, Jackson-Pratt drain tubing for repeated drainage of pleural fluid. Drains were used successfully in the 3 dogs for periods of 6 weeks, 11 weeks, and > 3 years.
Findings suggest that subcutaneous vascular access ports attached to intrathoracic drain tubing may be an effective way to remove recurrent pleural effusion in dogs.
Members of the Cool protein family contain SH3, Dbl, and pleckstrin homology domains and are binding partners for the p21-activated kinase (PAK). Using the yeast two-hybrid screen, we identified ...Cbl-b as a Cool family binding partner. We co-immunoprecipitated endogenous Cool and Cbl-b from a variety of breast cancer cell lines. The Cool–Cbl-b interaction requires the SH3 domain of Cool and competes with the binding of PAK to Cool proteins. Expression of Cbl-b effectively blocks the ability of Cool-2 to stimulate PAK, thus providing an additional mechanism, aside from catalyzing receptor ubiquitination, by which Cbl-b acts as a negative regulator for signaling activities requiring PAK activation.
Cell replacement therapy is emerging as a promising treatment platform for many endocrine disorders and hormone deficiency diseases. The survival of cells within delivery devices is, however, often ...limited due to low oxygen levels in common transplantation sites. Additionally, replacing implanted devices at the end of the graft lifetime is often unfeasible and, where possible, generally requires invasive surgical procedures. Here, the design and testing of a modular transcutaneous biphasic (BP) cell delivery device that provides enhanced and unlimited oxygen supply by direct contact with the atmosphere is presented. Critically, the cell delivery unit is demountable from the fixed components of the device, allowing for surgery‐free refilling of the therapeutic cells. Mass transfer studies show significantly improved performance of the BP device in comparison to subcutaneous controls. The device is also tested for islet encapsulation in an immunocompetent diabetes rodent model. Robust cell survival and diabetes correction is observed following a rat‐to‐mouse xenograft. Lastly, nonsurgical cell refilling is demonstrated in dogs. These studies show the feasibility of this novel device for cell replacement therapies.
A refillable transcutaneous cell encapsulation device is reported. Inspired by the biphasic physiology of the cornea, the device achieves elevated oxygen levels by direct contact with the atmosphere and provides environmental protection by application of a perfluorinated oil‐infused polymer nanomembrane. Diabetes correction is accomplished in mice and nonsurgical cell refilling is achieved in dogs.
Cell encapsulation represents a promising therapeutic strategy for many hormone-deficient diseases such as type 1 diabetes (T1D). However, adequate oxygenation of the encapsulated cells remains a ...challenge, especially in the poorly oxygenated subcutaneous site. Here, we present an encapsulation system that generates oxygen (O
) for the cells from their own waste product, carbon dioxide (CO
), in a self-regulated (i.e., "inverse breathing") way. We leveraged a gas-solid (CO
-lithium peroxide) reaction that was completely separated from the aqueous cellular environment by a gas permeable membrane. O
measurements and imaging validated CO
-responsive O
release, which improved cell survival in hypoxic conditions. Simulation-guided optimization yielded a device that restored normoglycemia of immunocompetent diabetic mice for over 3 months. Furthermore, functional islets were observed in scaled-up device implants in minipigs retrieved after 2 months. This inverse breathing device provides a potential system to support long-term cell function in the clinically attractive subcutaneous site.
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