Aquaporin 11 variant associates with kidney disease in type 2 diabetic patients.

Kidney disease, a common complication of diabetes, associates with poor prognosis. Our previous animal model studies linked aquaporin (AQP)11 to acute kidney injury, hyperglycemia-induced renal impairment, and kidney disease in diabetes. Here, we report the AQP11 rs2276415 variant as a genetic factor placing type 2 diabetic patients at greater risk for the development of kidney disease. We performed two independent retrospective case-control studies in 1,075 diabetic and 1,619 nondiabetic individuals who were identified in the Synthetic Derivative Database with DNA samples in the BioVU DNA repository at Vanderbilt University (Nashville, TN). A χ(2)-test and multivariable logistic regression analysis with adjustments for age, sex, baseline serum creatinine, and underlying comorbid disease covariates showed a significant association between rs2276415 and the prevalence of any event of acute kidney injury and chronic kidney disease (CKD) in diabetic patients but not in patients without diabetes. This result was replicated in the second independent study. Diabetic CKD patients over 55 yrs old with the minor AQP11 allele had a significantly faster progression of estimated glomerular filtration rate decline than patients with the wild-type genotype. Three-dimensional structural analysis suggested a functional impairment of AQP11 with rs2276415, which could place diabetic patients at a higher risk for kidney disease. These studies identified rs2276415 as a candidate genetic factor predisposing patients with type 2 diabetes to CKD.

Activation of Rac by Asef2 promotes myosin II-dependent contractility to inhibit cell migration on type I collagen.

Non-muscle myosin II (MyoII) contractility is central to the regulation of numerous cellular processes, including migration. Rho is a well-characterized modulator of actomyosin contractility, but the function of other GTPases, such as Rac, in regulating contractility is currently not well understood. Here, we show that activation of Rac by the guanine nucleotide exchange factor Asef2 (also known as SPATA13) impairs migration on type I collagen through a MyoII-dependent mechanism that enhances contractility. Knockdown of endogenous Rac or treatment of cells with a Rac-specific inhibitor decreases the amount of active MyoII, as determined by serine 19 (S19) phosphorylation, and negates the Asef2-promoted increase in contractility. Moreover, treatment of cells with blebbistatin, which inhibits MyoII activity, abolishes the Asef2-mediated effect on migration. In addition, Asef2 slows the turnover of adhesions in protrusive regions of cells by promoting large mature adhesions, which has been linked to actomyosin contractility, with increased amounts of active ß1 integrin. Hence, our data reveal a new role for Rac activation, promoted by Asef2, in modulating actomyosin contractility, which is important for regulating cell migration and adhesion dynamics.

A framework for evaluating the appropriateness of clinical decision support alerts and responses.

OBJECTIVE: Alerting systems, a type of clinical decision support, are increasingly prevalent in healthcare, yet few studies have concurrently measured the appropriateness of alerts with provider responses to alerts. Recent reports of suboptimal alert system design and implementation highlight the need for better evaluation to inform future designs. The authors present a comprehensive framework for evaluating the clinical appropriateness of synchronous, interruptive medication safety alerts. METHODS: Through literature review and iterative testing, metrics were developed that describe successes, justifiable overrides, provider non-adherence, and unintended adverse consequences of clinical decision support alerts. The framework was validated by applying it to a medication alerting system for patients with acute kidney injury (AKI). RESULTS: Through expert review, the framework assesses each alert episode for appropriateness of the alert display and the necessity and urgency of a clinical response. Primary outcomes of the framework include the false positive alert rate, alert override rate, provider non-adherence rate, and rate of provider response appropriateness. Application of the framework to evaluate an existing AKI medication alerting system provided a more complete understanding of the process outcomes measured in the AKI medication alerting system. The authors confirmed that previous alerts and provider responses were most often appropriate. CONCLUSION: The new evaluation model offers a potentially effective method for assessing the clinical appropriateness of synchronous interruptive medication alerts prior to evaluating patient outcomes in a comparative trial. More work can determine the generalizability of the framework for use in other settings and other alert types.

Hypercalcemia in pregnancy: a case of milk-alkali syndrome.

Milk-alkali syndrome is a rare cause of hypercalcemia characterized by the triad of hypercalcemia, renal insufficiency, and metabolic alkalosis that results from the overconsumption of calcium containing products. In the setting of pregnancy where there is a physiologic increase in calcium absorption, milk-alkali syndrome can be potentially life threatening. We report a case of a 26-year-old woman in her second trimester of pregnancy who presented with 2 weeks of flank pain, nausea, vomiting, anorexia, headache, and lightheadedness. The history revealed consumption of a large quantity of milk, calcium carbonate antacid, and calcium-containing prenatal vitamins. Her symptoms and hypercalcemia resolved with intravenous fluids and a loop diuretic. With the increased use of calcium carbonate for peptic ulcer disease, gastroesophageal reflux disease, and osteoporosis, milk-alkali syndrome has experienced a resurgence and must be considered in the differential diagnosis of hypercalcemia. In this clinical vignette we review the literature on milk-alkali syndrome in pregnancy and discuss important diagnostic and therapeutic considerations when managing the pregnant patient with hypercalcemia.

Integrin alpha3beta1-dependent activation of FAK/Src regulates Rac1-mediated keratinocyte polarization on laminin-5.

Upon epidermal wounding, keratinocytes at the wound edge become activated, deposit newly synthesized laminin-5 into the extracellular matrix, and migrate into the wound bed. The interaction between integrin alpha3beta1 and laminin-5 is essential for establishment of a stable, leading lamellipodium and persistent keratinocyte migration. We previously showed that integrin alpha3beta1 activates the Rho family GTPase Rac1 and regulates Rac1-dependent formation of polarized, leading lamellipodia in migrating keratinocytes. In the present study, we explored the role of focal adhesion kinase (FAK) and src signaling in this process. We show that overexpression of the FAK inhibitor FAK-related non-kinase or of the FAK(Y397F) auto-phosphorylation mutant, induced abnormal, non-polarized spreading of keratinocytes on laminin-5. Integrin alpha3beta1 was required for full FAK auto-phosphorylation at Y397, and subsequent src kinase-dependent phosphorylation of FAK at residues Y861 and Y925, sites responsible for promoting signal transduction downstream of FAK, indicating that alpha3beta1 regulates the coordination of FAK/src signal transduction. Inhibiting either src kinase activity or FAK signaling interfered with alpha3beta1-mediated Rac1 activation and polarized cell spreading. These findings reveal a novel pathway in migratory keratinocytes wherein alpha3beta1-laminin-5 interactions regulate src kinase signaling through FAK, promoting Rac1 activation and polarized lamellipodium extension.

Integrin alpha3beta1 directs the stabilization of a polarized lamellipodium in epithelial cells through activation of Rac1.

Epithelial cell migration is a crucial event in wound healing, yet little is known about mechanisms whereby integrins regulate epithelial cell polarization and migration. In the present work, we demonstrate the importance of adhesion through the alpha3beta1 integrin in promoting the stabilization of leading lamellipodia in migrating keratinocytes. We demonstrate that this integrin is found at the leading edge of migrating keratinocytes and that inhibition of alpha3beta1 binding to laminin-5 prevents the formation of stable leading lamellipodia. Consistent with this observation, keratinocytes derived from alpha3beta1-deficient mice fail to form stable leading lamellipodia but retain the ability to form actin-containing protrusions that rapidly extend and retract from the cell membrane. Formation of a leading lamellipodium also requires alpha3beta1-dependent activation of Rac1, because alpha3beta1-deficient keratinocytes show decreased activation of Rac1 compared with alpha3beta1-expressing cells, and formation of stable leading lamellipodia can be inhibited in the latter cells by expression of the dominant negative Rac1 mutant Rac1N17. Furthermore, alpha3beta1-deficient keratinocytes expressing constitutively active Rac1L61 failed to form stable lamellipodia when plated onto laminin-5, demonstrating that alpha3beta1 is required for Rac1-mediated formation of a stable lamellipodium. These observations identify a crucial role for integrin-mediated adhesion and signaling in the formation of large, polarized, stable lamellipodia by migrating epithelial cells. To our knowledge, this study is the first to demonstrate that signal transduction through a specific integrin is required to direct the development of a lamellipodium from an initial protrusion and promote persistent epithelial cell migration.