Sirolimus attenuates disease progression in an orthologous mouse model of human autosomal dominant polycystic kidney disease

In autosomal dominant polycystic kidney disease (ADPKD), abnormal proliferation of tubular cells drives cyst development and growth. Sirolimus, an inhibitor of the protein kinase mammalian target of rapamycin (mTOR) and a potent anti-proliferative agent, decreases cyst growth in several genetically distinct rodent models of polycystic kidney disease (PKD). We determined here the effect of sirolimus on renal cyst growth in Pkd2WS25/− mice; an ortholog of human ADPKD involving mutation of the Pkd2 gene. In Pkd2WS25/− mice treated with sirolimus, both the two kidney/total body weight (2K/TBW) ratio and the cyst volume density (CVD) were significantly decreased by over half compared with untreated mice suffering with PKD. However, there was no effect on the increased blood urea nitrogen (BUN) levels as an index of kidney function. There are two distinct complexes containing mTOR depending on its binding partners: mTORC1 and mTORC2. Western blot analysis of whole kidney lysates and immunohistochemistry of the cysts found that phospho-S6 ribosomal protein, a marker of mTORC1 activity, was increased in Pkd2WS25/− mice and its phosphorylation was decreased by sirolimus treatment. Phospho-Akt at serine 473, a marker associated with mTORC2 activity, was not different between Pkd2WS25/− mice and normal littermate controls. Hence, our study found that inhibition of mTORC1 by sirolimus correlated with decreased renal cyst growth in this model of human ADPKD but had no effect on the decline in renal function

Regulated ion transport in mouse liver cyst epithelial cells

AbstractDerived from bile duct epithelia (BDE), secretion by liver cyst-lining epithelia is positioned to drive cyst expansion but the responsible ion flux pathways have not been characterized. Cyst-lining epithelia were isolated and cultured into high resistance monolayers to assess the ion secretory pathways. Electrophysiologic studies showed a marked rate of constitutive transepithelial ion transport, including Cl− secretion and Na+ absorption. Na+ absorption was amiloride-sensitive, suggesting the activation of epithelial sodium channels (ENaC). Further, both cAMPi and extracellular ATP induced robust secretory responses. Western blotting and immunohistologic analysis of liver cyst epithelia demonstrated expression of P2X4, a potent purinergic receptor in normal BDE. Luminometry and bioassaying measured physiologically relevant levels of ATP in a subset of liver cyst fluid samples. Liver cyst epithelia also displayed a significant capacity to degrade extracellular ATP. In conclusion, regulated ion transport pathways are present in liver cyst epithelia and are positioned to direct fluid secretion into the lumen of liver cysts and promote increases in liver cyst expansion and growth

Duplex ultrasound imaging alone is sufficient for midterm endovascular aneurysm repair surveillance: A cost analysis study and prospective comparison with computed tomography scan

ObjectiveEarly in our experience with endovascular aortic aneurysm repair (EVAR) we performed both serial computed tomography scans and duplex ultrasound (DU) imaging in our post-EVAR surveillance regimen. Later we conducted a prospective study with DU imaging as the sole surveillance study and determined cost savings and outcome using this strategy.MethodsFrom September 21, 1998, to May 30, 2008, 250 patients underwent EVAR at our hospital. Before July 1, 2004, EVAR patients underwent CT and DU imaging performed every 6 months during the first year and then annually if no problems were identified (group 1). We compared aneurysm sac size, presence of endoleak, and graft patency between the two scanning modalities. After July 1, 2004, patients underwent surveillance using DU imaging as the sole surveillance study unless a problem was detected (group 2). CT and DU imaging charges for each regimen were compared using our 2008 health system pricing and Medicare reimbursements. All DU examinations were performed in our accredited noninvasive vascular laboratory by experienced technologists. Statistical analysis was performed using Pearson correlation coefficient.ResultsDU and CT scans were equivalent in determining aneurysm sac diameter after EVAR (P < .001). DU and CT were each as likely to falsely suggest an endoleak when none existed and were as likely to miss an endoleak. Using DU imaging alone would have reduced cost of EVAR surveillance by 29% ($534,356) in group 1. Cost savings of$1595 per patient per year were realized in group 2 by eliminating CT scan surveillance. None of the group 2 patients sustained an adverse event such as rupture, graft migration, or limb occlusion as a result of having DU imaging performed as the sole follow-up modality.ConclusionSurveillance of EVAR patients can be performed accurately, safely, and cost-effectively with DU as the sole imaging study

A pilot intervention combining assessment and feedback with communication training and behavioral nudges to increase HPV vaccine uptake

Human papillomavirus (HPV) causes >40,000 cancer diagnoses each year, yet vaccination rates remain low because widespread implementation of strategies to increase vaccinations has not occurred. Behavioral nudges have demonstrated efficacy in improving uptake of desired behaviors in health care settings but have not been tested for increasing HPV vaccinations. We assessed the impact of an intervention combining behavioral nudges with other proven strategies (i.e., assessment and feedback, provider communication training) on HPV vaccination rates and parental satisfaction in four Midwestern pediatric, outpatient practices. Practices were randomly assigned to receive either assessment and feedback or assessment and feedback combined with vaccine communication training and behavioral nudges in the form of vaccine commitment posters. Providers (n = 16) completed surveys regarding vaccine policies and parents (n = 215) reported on their child’s vaccine history and satisfaction with the consultation. Three practices increased HPV vaccination rates (1–10%); however, there was no statistically significant difference by study arm. Most parents (M age 41.3; SD 8.1; 85% female, 68% White) indicated their child had previously initiated the HPV vaccine series (61%) and 72% indicated receipt of an HPV vaccine during the study visit. Concerns among HPV vaccine-hesitant parents (28%) included vaccine safety and believing the vaccine is unnecessary (40%). Most parents were satisfied with their consultation. Practices in both intervention groups increased vaccination rates. While some parents continue to harbor concerns about vaccine safety and necessity, parents welcomed discussions about HPV and were satisfied with their provider’s communication regardless of their vaccine decisions

Extracellular nucleotides stimulate Cl− currents in biliary epithelia through receptor-mediated IP3 and Ca2+ release

Extracellular ATP regulates bile formation by binding to P2 receptors on cholangiocytes and stimulating transepithelial Cl− secretion. However, the specific signaling pathways linking receptor binding to Cl− channel activation are not known. Consequently, the aim of these studies in human Mz-Cha-1 biliary cells and normal rat cholangiocyte monolayers was to assess the intracellular pathways responsible for ATP-stimulated increases in intracellular Ca2+ concentration ([Ca2+]i) and membrane Cl− permeability. Exposure of cells to ATP resulted in a rapid increase in [Ca2+]i and activation of membrane Cl− currents; both responses were abolished by prior depletion of intracellular Ca2+. ATP-stimulated Cl− currents demonstrated mild outward rectification, reversal at ECl−, and a single-channel conductance of ∼17 pS, where E is the equilibrium potential. The conductance response to ATP was inhibited by the Cl− channel inhibitors NPPB and DIDS but not the CFTR inhibitor CFTRinh-172. Both ATP-stimulated increases in [Ca2+]i and Cl− channel activity were inhibited by the P2Y receptor antagonist suramin. The PLC inhibitor U73122 and the inositol 1,4,5-triphosphate (IP3) receptor inhibitor 2-APB both blocked the ATP-stimulated increase in [Ca2+]i and membrane Cl− currents. Intracellular dialysis with purified IP3 activated Cl− currents with identical properties to those activated by ATP. Exposure of normal rat cholangiocyte monolayers to ATP increased short-circuit currents (Isc), reflecting transepithelial secretion. The Isc was unaffected by CFTRinh-172 but was significantly inhibited by U73122 or 2-APB. In summary, these findings indicate that the apical P2Y-IP3 receptor signaling complex is a dominant pathway mediating biliary epithelial Cl− transport and, therefore, may represent a potential target for increasing secretion in the treatment of cholestatic liver disease