Identification of structures for ion channel kinetic models.

Markov models of ion channel dynamics have evolved as experimental advances have improved our understanding of channel function. Past studies have examined limited sets of various topologies for Markov models of channel dynamics. We present a systematic method for identification of all possible Markov model topologies using experimental data for two types of native voltage-gated ion channel currents: mouse atrial sodium currents and human left ventricular fast transient outward potassium currents. Successful models identified with this approach have certain characteristics in common, suggesting that aspects of the model topology are determined by the experimental data. Incorporating these channel models into cell and tissue simulations to assess model performance within protocols that were not used for training provided validation and further narrowing of the number of acceptable models. The success of this approach suggests a channel model creation pipeline may be feasible where the structure of the model is not specified a priori.

Proteomic analysis identifies key differences in the cardiac interactomes of dystrophin and micro-dystrophin.

ΔR4-R23/ΔCT micro-dystrophin (µDys) is a miniaturized version of dystrophin currently evaluated in a Duchenne muscular dystrophy (DMD) gene therapy trial to treat skeletal and cardiac muscle disease. In pre-clinical studies, µDys efficiently rescues cardiac histopathology, but only partially normalizes cardiac function. To gain insights into factors that may impact the cardiac therapeutic efficacy of µDys, we compared by mass spectrometry the composition of purified dystrophin and µDys protein complexes in the mouse heart. We report that compared to dystrophin, µDys has altered associations with α1- and ß2-syntrophins, as well as cavins, a group of caveolae-associated signaling proteins. In particular, we found that membrane localization of cavin-1 and cavin-4 in cardiomyocytes requires dystrophin and is profoundly disrupted in the heart of mdx5cv mice, a model of DMD. Following cardiac stress/damage, membrane-associated cavin-4 recruits the signaling molecule ERK to caveolae, which activates key cardio-protective responses. Evaluation of ERK signaling revealed a profound inhibition, below physiological baseline, in the mdx5cv mouse heart. Expression of µDys in mdx5cv mice prevented the development of cardiac histopathology but did not rescue membrane localization of cavins nor did it normalize ERK signaling. Our study provides the first comparative analysis of purified protein complexes assembled in vivo by full-length dystrophin and a therapeutic micro-dystrophin construct. This has revealed disruptions in cavins and ERK signaling that may contribute to DMD cardiomyopathy. This new knowledge is important for ongoing efforts to prevent and treat heart disease in DMD patients.

Polycystin 2 is increased in disease to protect against stress-induced cell death.

Polycystin 2 (PC2 or TRPP1, formerly TRPP2) is a calcium-permeant Transient Receptor Potential (TRP) cation channel expressed primarily on the endoplasmic reticulum (ER) membrane and primary cilia of all cell and tissue types. Despite its ubiquitous expression throughout the body, studies of PC2 have focused primarily on its role in the kidney, as mutations in PC2 lead to the development of autosomal dominant polycystic kidney disease (ADPKD), a debilitating condition for which there is no cure. However, the endogenous role that PC2 plays in the regulation of general cellular homeostasis remains unclear. In this study, we measure how PC2 expression changes in different pathological states, determine that its abundance is increased under conditions of cellular stress in multiple tissues including human disease, and conclude that PC2-deficient cells have increased susceptibility to cell death induced by stress. Our results offer new insight into the normal function of PC2 as a ubiquitous stress-sensitive protein whose expression is up-regulated in response to cell stress to protect against pathological cell death in multiple diseases.

Other Surgeries in Patients with Inflammatory Bowel Disease.

Patients with inflammatory bowel disease (IBD) will often require abdominal surgical intervention for indications not directly related to their IBD. Because these patients often have a history of multiple previous abdominal operations and/or ostomies, they are at increased risk for incisional and parastomal hernias. They may also have develop symptomatic cholelithiasis, chronic pain, or desmoid disease. All of these potentially surgical issues may require special consideration in the IBD population.

Regional Differences in mRNA and lncRNA Expression Profiles in Non-Failing Human Atria and Ventricles.

The four chambers of the human heart play distinct roles in the maintenance of normal cardiac function, and are differentially affected by inherited/acquired cardiovascular disease. To probe the molecular determinants of these functional differences, we examined mRNA and lncRNA expression profiles in the left (LA) and right (RA) atria, the left (LV) and right (RV) ventricles, and the interventricular septum (IVS) of non-failing human hearts (N = 8). Analysis of paired atrial and ventricular samples (n = 40) identified 5,747 mRNAs and 2,794 lncRNAs that were differentially (>1.5 fold; FDR < 0.05) expressed. The largest differences were observed in comparisons between the atrial (RA/LA) and ventricular (RV/LV/IVS) samples. In every case (e.g., LA vs LV, LA vs RV, etc.), >2,300 mRNAs and >1,200 lncRNAs, corresponding to 17-28% of the total transcripts, were differentially expressed. Heterogeneities in mRNA/lncRNA expression profiles in the LA and RA, as well as in the LV, RV and IVS, were also revealed, although the numbers of differentially expressed transcripts were substantially smaller. Gender differences in mRNA and lncRNA expression profiles were also evident in non-failing human atria and ventricles. Gene ontology classification of differentially expressed gene sets revealed chamber-specific enrichment of numerous signaling pathways.

Differential Expression and Remodeling of Transient Outward Potassium Currents in Human Left Ventricles.

BACKGROUND: Myocardial, transient, outward currents, Ito, have been shown to play pivotal roles in action potential (AP) repolarization and remodeling in animal models. The properties and contribution of Ito to left ventricular (LV) repolarization in the human heart, however, are poorly defined. METHODS AND RESULTS: Whole-cell, voltage-clamp recordings, acquired at physiological (35°C to 37°C) temperatures, from myocytes isolated from the LV of nonfailing human hearts identified 2 distinct transient currents, Ito,fast (Ito,f) and Ito,slow (Ito,s), with significantly (P<0.0001) different rates of recovery from inactivation and pharmacological sensitives: Ito,f recovers in ≈10 ms, 100× faster than Ito,s, and is selectively blocked by the Kv4 channel toxin, SNX-482. Current-clamp experiments revealed regional differences in AP waveforms, notably a phase 1 notch in LV subepicardial myocytes. Dynamic clamp-mediated addition/removal of modeled human ventricular Ito,f, resulted in hyperpolarization or depolarization, respectively, of the notch potential, whereas slowing the rate of Ito,f inactivation resulted in AP collapse. AP-clamp experiments demonstrated that changes in notch potentials modified the time course and amplitudes of voltage-gated Ca2+ currents, ICa. In failing LV subepicardial myocytes, Ito,f was reduced and Ito,s was increased, notch and plateau potentials were depolarized (P<0.0001) and AP durations were prolonged (P<0.001). CONCLUSIONS: Ito,f and Ito,s are differentially expressed in nonfailing human LV, contributing to regional heterogeneities in AP waveforms. Ito,f regulates notch and plateau potentials and modulates the time course and amplitude of ICa. Slowing Ito,f inactivation results in dramatic AP shortening. Remodeling of Ito,f in failing human LV subepicardial myocytes attenuates transmural differences in AP waveforms.

Sweet-cheeks vs. pea-brain: embodiment, valence, and task all influence the emotional salience of language.

Previous research has found that more embodied insults (e.g. numbskull) are identified faster and more accurately than less embodied insults (e.g. idiot). The linguistic processing of embodied compliments has not been well explored. In the present study, participants completed two tasks where they identified insults and compliments, respectively. Half of the stimuli were more embodied than the other half. We examined the late positive potential (LPP) component of event-related potentials in early (400-500 ms), middle (500-600 ms), and late (600-700 ms) time windows. Increased embodiment resulted in improved response accuracy to compliments in both tasks, whereas it only improved accuracy for insults in the compliment detection task. More embodied stimuli elicited a larger LPP than less embodied stimuli in the early time window. Insults generated a larger LPP in the late time window in the insult task; compliments generated a larger LPP in the early window in the compliment task. These results indicate that electrophysiological correlates of emotional language perception are sensitive to both top-down and bottom-up processes.

Preoperative Immunonutrition and Elective Colorectal Resection Outcomes.

BACKGROUND: Randomized controlled trials demonstrate the efficacy of arginine-enriched nutritional supplements (immunonutrition) in reducing complications after surgery. The effectiveness of preoperative immunonutrition has not been evaluated in a community setting. OBJECTIVE: This study aims to determine whether immunonutrition before elective colorectal surgery improves outcomes in the community at large. DESIGN: This is a prospective cohort study with a propensity score-matched comparative effectiveness evaluation. SETTINGS: This study was conducted in Washington State hospitals in the Surgical Care Outcomes Assessment Program from 2012 to 2015. PATIENTS: Adults undergoing elective colorectal surgery were selected. INTERVENTIONS: Surgeons used a preoperative checklist that recommended that patients take oral immunonutrition (237 mL, 3 times daily) for 5 days before elective colorectal resection. MAIN OUTCOME MEASURES: Serious adverse events (infection, anastomotic leak, reoperation, and death) and prolonged length of stay were the primary outcomes measured. RESULTS: Three thousand three hundred seventy-five patients (mean age 59.9 ± 15.2 years, 56% female) underwent elective colorectal surgery. Patients receiving immunonutrition more commonly were in a higher ASA class (III-V, 44% vs 38%; p = 0.01) or required an ostomy (18% vs 14%; p = 0.02). The rate of serious adverse events was 6.8% vs 8.3% (p = 0.25) and the rate of prolonged length of stay was 13.8% vs 17.3% (p = 0.04) in those who did and did not receive immunonutrition. After propensity score matching, covariates were similar among 960 patients. Although differences in serious adverse events were nonsignificant (relative risk, 0.76; 95% CI, 0.49-1.16), prolonged length of stay (relative risk, 0.77; 95% CI, 0.58-1.01 p = 0.05) was lower in those receiving immunonutrition. LIMITATIONS: Patient compliance with the intervention was not measured. Residual confounding, including surgeon-level heterogeneity, may influence estimates of the effect of immunonutrition. CONCLUSIONS: Reductions in prolonged length of stay, likely related to fewer complications, support the use of immunonutrition in quality improvement initiatives related to elective colorectal surgery. This population-based study supports previous trials of immunonutrition, but shows a lower magnitude of benefit, perhaps related to compliance or a lower rate of adverse events, highlighting the value of community-based assessments of comparative effectiveness.

Rectourethral fistulas: A comparison of the National Inpatient Sample and the American College of Surgeons National Surgical Quality Improvement Program.

BACKGROUND: The National Surgical Quality Improvement Program (NSQIP) and the National Inpatient Sample (NIS) may be used to evaluate outcomes for uncommon conditions such as rectourethral fistulas (RUFs). We sought to review cases of RUFs and compare variables from both registries to evaluate disparities among reported data. METHODS: Review of NSQIP (2005-2013) and NIS (2006-2011) of all patients with a RUF or RUF repair based on ICD-9-CM or CPT coding. RESULTS: The NSQIP and NIS data sets were compared based on International Classification of Diseases, 9th Revision, Clinical Modification diagnosis coding for a RUF (599.1; American College of Surgeons National Surgical Quality Improvement Program: n = 286, NIS: n = 2,357). Comorbidities varied between data sets, and in-hospital morbidity in RUF cases was greater in the NIS vs NSQIP data sets (48% vs 11%; P < .01). Further analysis identified similar outcomes when cases of a RUF that underwent an operation were compared in the NSQIP (n = 284) and NIS (n = 274) database. CONCLUSIONS: This study represents the largest cohort of RUF cases and characterizes how using variables from both databases better elucidates details of this rare condition. These results exhibit how evaluating comparable metrics demonstrates inconsistencies between databases.

Is Modern Medical Management Changing Ultimate Patient Outcomes in Inflammatory Bowel Disease?

BACKGROUND: The impact of modern medical management of inflammatory bowel disease (IBD) on surgical necessity and outcomes remains unclear. We hypothesized that surgery rates have decreased while outcomes have worsened due to operating on "sicker" patients since the introduction of biologic medications. METHODS: The Nationwide Inpatient Sample and ICD-9-CM codes were used to identify inpatient admissions for Crohn's disease and ulcerative colitis. Trends in IBD nutrition, surgeries, and postoperative complications were determined. RESULTS: There were 191,743 admissions for IBD during the study period. Surgery rates were largely unchanged over the study period, ranging from 9 to 12 % of admissions in both Crohn's disease and ulcerative colitis. The rate of poor nutrition increased by 67 % in ulcerative colitis and by 83 % in Crohn's disease. Rates of postoperative anastomotic leak (10.2-13.9 %) were unchanged over the years. Postoperative infection rates decreased by 17 % in Crohn's disease (18 % in 2003 to 15 % in 2012; P < 0.001) but did not show a trend in any direction in ulcerative colitis. CONCLUSIONS: Rates of IBD surgery have remained stable while postoperative infectious complications have remained stable or decreased since the implementation of biologic therapies. We identified an increase in poor nutrition in surgical patients.

Colonoscopy after Hinchey I and II left-sided diverticulitis: utility or futility?

BACKGROUND: Modern 64- to 128-slice computed tomography (CT) scanners have questioned the need for routine colonoscopy after hospital admission for presumed uncomplicated diverticulitis. METHODS: This is a retrospective review of all patients (>18 years) who underwent planned colonoscopy after admission for Hinchey I or II acute diverticulitis (January 2009 to January 2014). The findings on the final radiologist report were then correlated with the colonoscopy results. RESULTS: In total, 110 patients (mean age, 55.2 ± 16; 46.4% female) underwent a subsequent colonoscopy (median, 60 days) after admission for diverticulitis. Overall, 102 patients (92.7%) had CT findings consistent with definitive diverticulitis, 6 patients had a diagnosis suggestive of diverticulitis on CT scan, and 2 patients had masses on their admission CT scans. Within the group with definitive diverticulitis, follow-up colonoscopy identified diverticulosis in 99 (97.0%), whereas the other 3 had normal findings. Of the patients with CT scans suggestive of diverticulitis, follow-up colonoscopy showed 3 with diverticulosis, 2 with malignancies, and 1 with nonspecific inflammation. The reliability of CT scans for diverticulitis compared with colonoscopy was found to have a kappa = .829 (P < .001; 95% confidence interval, .629, 1.21). CONCLUSIONS: Follow-up colonoscopy should be performed when a CT scan suggests malignancy, nonspecific inflammatory findings, or the patient is otherwise due for routine screening or surveillance. In this study, there was no benefit of follow-up colonoscopy in patients with CT-confirmed diverticulitis in the absence of other concerning or indeterminate findings.

Screening or Symptoms? How Do We Detect Colorectal Cancer in an Equal Access Health Care System?

BACKGROUND: Detection of colorectal cancer ideally occurs at an early stage through proper screening. We sought to establish methods by which colorectal cancers are diagnosed within an equal access military health care population and evaluate the correlation between TNM stage at colorectal cancer diagnosis and diagnostic modality (i.e., symptomatic detection vs screen detection). MATERIALS AND METHODS: A retrospective chart review of all newly diagnosed colorectal cancer patients from January 2007 to August 2014 was conducted at the authors' equal access military institution. We evaluated TNM stage relative to diagnosis by screen detection (fecal occult blood test, flexible sigmoidoscopy, CT colonography, colonoscopy) or symptomatic evaluation (diagnostic colonoscopy or surgery). RESULTS: Of 197 colorectal cancers diagnosed (59 % male; mean age 62 years), 50 (25 %) had stage I, 47 (24 %) had stage II, 70 (36 %) had stage III, and 30 (15 %) had stage IV disease. Twenty-five percent of colorectal cancers were detected via screen detection (3 % by fecal occult blood testing (FOBT), 0.5 % by screening CT colonography, 17 % by screening colonoscopy, and 5 % by surveillance colonoscopy). One hundred forty-eight (75 %) were diagnosed after onset of signs or symptoms. The preponderance of these was advanced-stage disease (stages III-IV), although >50 % of stage I-II disease also had signs or symptoms at diagnosis. The most common symptoms were rectal bleeding (45 %), abdominal pain (35 %), and change in stool caliber (27 %). The most common overall sign was anemia (60 %). Screening FOBT (odds ratio (OR) 8.7, 95 % confidence interval (CI) 1.0-78.3; P = 0.05) independently predicted early diagnosis with stage I-II disease. Patient gender and ethnicity were not associated with cancer stage at diagnosis. CONCLUSIONS: Despite equal access to colorectal cancer screening, diagnosis after development of symptomatic cancer remains more common. Fecal occult blood screen detection is associated with early stage at colorectal cancer diagnosis and is the focus for future initiatives.