Statistical Mechanics of an Elastically Pinned Membrane: Equilibrium Dynamics and Power Spectrum.

In biological settings, membranes typically interact locally with other membranes: the extracellular matrix in the exterior or internal cellular structures such as the cytoskeleton, locally pinning the membrane. Characterizing the dynamical properties of such interactions presents a difficult task. Significant progress has been achieved through simulations and experiments, yet analytical progress in modeling pinned membranes has been impeded by the complexity of governing equations. Here, we circumvent these difficulties by calculating analytically the time-dependent Green's function of the operator governing the dynamics of an elastically pinned membrane in a hydrodynamic surrounding and subject to external forces. This enables us to calculate the equilibrium power spectral density for an overdamped membrane pinned by an elastic, permanently attached spring subject to thermal excitations. By considering the effects of the finite experimental resolution on the measured spectra, we show that the elasticity of the pinning can be extracted from the experimentally measured spectrum. Membrane fluctuations can thus be used as a tool to probe mechanical properties of the underlying structures. Such a tool may be particularly relevant in the context of cell mechanics, in which the elasticity of the membrane's attachment to the cytoskeleton could be measured.

Socioeconomic and patient-related factors for the management of male urethral stricture disease.

PURPOSE: We sought to determine the socioeconomic and patient factors that influence the utilization of urethroplasty and location of management in the treatment of male urethral stricture disease. METHODS: A retrospective review using the Healthcare Cost and Utilization Project State Inpatient and Ambulatory Surgery and Services Databases for California and Florida was performed. Adult men with a diagnosis of urethral stricture who underwent treatment with urethroplasty or endoscopic dilation/urethrotomy between 2007 and 2011 in California and 2009 and 2014 in Florida were identified by ICD-9 or CPT codes. Patients were categorized based on whether they had a urethroplasty or serial dilations/urethrotomies. Patients were assessed for age, insurance provider, median household income by zip code, Charlson Comorbidity Index, race, prior stricture management, and location of the index procedure. A multivariable logistic regression model was fit to assess factors influencing treatment modality (urethroplasty vs endoscopic management) and location (teaching hospital vs non-teaching hospital). RESULTS: Twenty seven thousand, five hundred and sixty-eight patients were identified that underwent treatment for USD. 25,864 (93.8%) treated via endoscopic approaches and 1704 (6.2%) treated with urethroplasty. Factors favoring utilization of urethroplasty include younger age, lower Charlson Comorbidity score, higher zip code median income quartile, private insurance, prior endoscopic treatment, and management at a teaching hospital. CONCLUSION: Socioeconomic predictors of urethroplasty utilization include higher income status and private insurance. Patient-specific factors influencing urethroplasty were younger age and fewer medical comorbidities. A primary driver of urethroplasty utilization was treatment at a teaching hospital. Older and Hispanic patients were less likely to seek care at these facilities.

Complications of Recognized and Unrecognized Iatrogenic Ureteral Injury at Time of Hysterectomy: A Population Based Analysis.

PURPOSE: Ureteral injury represents an uncommon but potentially morbid surgical complication. We sought to characterize the complications of iatrogenic ureteral injury and assess the effect of recognized vs delayed recognition on patient outcomes. MATERIALS AND METHODS: Patients who underwent hysterectomy were identified in the Healthcare Cost and Utilization Project California State Inpatient Database for 2007 to 2011. Ureteral injuries were identified and categorized as recognized-diagnosed/repaired on the day of hysterectomy and unrecognized-diagnosed/repaired postoperatively. We assessed the outcomes of 90-day hospital readmission as well as 1-year outcomes of nephrostomy tube placement, urinary fistula, acute renal failure, sepsis and overall mortality. The independent effects of recognized and unrecognized ureteral injuries were determined on multivariate analysis. RESULTS: Ureteral injury occurred in 1,753 of 223,872 patients (0.78%) treated with hysterectomy and it was unrecognized in 1,094 (62.4%). The 90-day readmission rate increased from a baseline of 5.7% to 13.4% and 67.3% after recognized and unrecognized injury, respectively. Nephrostomy tubes were required in 2.3% of recognized and 23.4% of unrecognized ureteral injury cases. Recognized and unrecognized ureteral injuries independently increased the risk of sepsis (aOR 2.0, 95% CI 1.2-3.5 and 11.9, 95% CI 9.9-14.3) and urinary fistula (aOR 5.9, 95% CI 2.2-16 and 124, 95% CI 95.7-160, respectively). During followup unrecognized ureteral injury increased the odds of acute renal insufficiency (aOR 23.8, 95% CI 20.1-28.2) and death (1.4, 95% CI 1.03-1.9, p = 0032). CONCLUSIONS: Iatrogenic ureteral injury increases the risk of hospital readmission and significant, potentially life threatening complications. Unrecognized ureteral injury markedly increases these risks, warranting a high level of suspicion for ureteral injury and a low threshold for diagnostic investigation.

Impact and treatment success of new-onset atrial fibrillation with rapid ventricular rate development in the surgical intensive care unit.

BACKGROUND: Atrial fibrillation (AF) with rapid ventricular rate (RVR; heart rate >100) in noncardiac postoperative surgical patients is associated with poor outcomes. The objective of this study was to evaluate the practice patterns of AF management in a surgical intensive care unit to determine practices associated with rate and rhythm control and additional outcomes. MATERIALS AND METHODS: Adult patients (≥18 y) admitted to the surgical intensive care unit (SICU) from June 2014 to June 2015 were retrospectively screened for the development of new-onset AF with RVR. Demographics, hospital course, evaluation and treatment of AF with RVR, and outcome were evaluated and analyzed. RESULTS: Thousand seventy patients were admitted to the SICU during the study period; 33 met inclusion criteria (3.1%). Twenty-six patients (79%) had rate and rhythm control within 48 h of AF with RVR onset. ß-Blockers were the most commonly used initial medication (67%) but were successful at rate and rhythm control in only 27% of patients (6/22). Amiodarone had the highest rate of success if used initially (5/6, 83%) and secondarily (11/13, 85%). Failure to control rate and rhythm was associated with a greater likelihood of comorbidities (100% versus 57%; P = 0.06). CONCLUSIONS: New-onset AF with RVR in the noncardiac postoperative patient is associated with a high mortality (21%). Amiodarone is the most effective treatment for rate and rhythm control. Failure to establish rate and rhythm control was associated with cardiac comorbidities. These results will help to form future algorithms for the treatment of AF with RVR in the SICU.

Implications of postoperative pulmonary aspiration following major urologic surgery.

INTRODUCTION: The purpose of this article is to assess the incidence of pulmonary aspiration following major urologic surgery, predictors of an aspiration event, and subsequent clinical outcomes. MATERIALS AND METHODS: The Healthcare Cost and Utilization Project State Inpatient Database for California between 2007-2011 was used to identify cystectomy, prostatectomy, partial and radical nephrectomy patients. Aspiration events were identified within 30 days of surgery. The primary outcome was 30 day mortality and secondary outcomes included total length of stay, discharge location, and diagnoses of acute renal failure, pneumonia or sepsis. Descriptive statistics were performed. A multivariable logistic regression was performed to determine independent predictors of an aspiration event. A separate nonparsimonious logistic regression was fit to determine the independent effect of an aspiration event on 30 day mortality. RESULTS: Of 84,837 major urologic surgery patients 319 (0.4%) had an aspiration event. Risk factors for aspiration included ileus, congestive heart failure, paraplegia, chronic lung disease, and age = 80 years (all p < 0.01). Aspiration patients had higher rates of renal failure (36.1% versus 2.5%), pneumonia (36.1% versus 2.5%), sepsis (35.7% versus 0.7%), a prolonged length of stay (17 days versus 3 days), and discharge to nursing facility(26.3% vs 2.3%) (all p<0.001). The 30 day mortality rate following aspiration was 20.7% compared to 0.8% (p < 0.001). Aspiration independently increases the risk of 30 day mortality (OR 3.1 (95%CI 2.2-4.5). CONCLUSIONS: Postoperative aspiration following major urologic surgery is a devastating complication and precautions must be undertaken in high risk patient populations to avoid such an event.

Contributions of Microtubule Dynamic Instability and Rotational Diffusion to Kinetochore Capture.

Microtubule dynamic instability allows search and capture of kinetochores during spindle formation, an important process for accurate chromosome segregation during cell division. Recent work has found that microtubule rotational diffusion about minus-end attachment points contributes to kinetochore capture in fission yeast, but the relative contributions of dynamic instability and rotational diffusion are not well understood. We have developed a biophysical model of kinetochore capture in small fission-yeast nuclei using hybrid Brownian dynamics/kinetic Monte Carlo simulation techniques. With this model, we have studied the importance of dynamic instability and microtubule rotational diffusion for kinetochore capture, both to the lateral surface of a microtubule and at or near its end. Over a range of biologically relevant parameters, microtubule rotational diffusion decreased capture time, but made a relatively small contribution compared to dynamic instability. At most, rotational diffusion reduced capture time by 25%. Our results suggest that while microtubule rotational diffusion can speed up kinetochore capture, it is unlikely to be the dominant physical mechanism for typical conditions in fission yeast. In addition, we found that when microtubules undergo dynamic instability, lateral captures predominate even in the absence of rotational diffusion. Counterintuitively, adding rotational diffusion to a dynamic microtubule increases the probability of end-on capture.

Impact of Post-Hospital Syndrome on Outcomes Following Elective, Ambulatory Surgery.

OBJECTIVE: The aim of this study was to investigate whether post-hospital syndrome (PHS) places patients undergoing elective hernia repair at increased risk for adverse postoperative events. SUMMARY OF BACKGROUND DATA: PHS is a transient period of health vulnerability following inpatient hospitalization for acute illness. PHS has been well studied in nonsurgical populations, but its effect on surgical outcomes is unclear. METHODS: State-specific datasets for California in 2011 available through the Healthcare Cost and Utilization Project (HCUP) were linked. Patients older than 18 years who underwent elective hernia repair were included. The primary exposure variable was PHS, defined as any inpatient admission within 90 days of an elective hernia repair performed in an ambulatory surgery center. The primary outcome was an adverse event, defined as any unplanned emergency department visit or inpatient admission within 30 days postoperatively. Mixed-effects logistic models were used for multivariable analyses. RESULTS: A total of 57,988 patients met inclusion criteria. The 30-day risk-adjusted adverse event rate was significantly higher for PHS patients versus non-PHS patients (11.8% vs 5.8%, P < 0.001). PHS patients were more likely than non-PHS patients to experience postoperative complications (odds ratio 2.2, 95% confidence interval 1.6-3.0). Adverse events attributable to PHS cost an additional $63,533.46 per 100 cases in California. The risk of adverse events due to PHS remained elevated throughout the 90-day window between hospitalization and surgery. CONCLUSIONS: Patients hospitalized within 90 days of an elective surgery are at increased risk of adverse events postoperatively. The impact of PHS on outcomes is independent of baseline patient characteristics, medical comorbidities, quality of center performing the surgery, and reason for hospitalization before elective surgery. Adverse events owing to PHS are costly and represent a quality improvement target.

Rates and Risk Factors for Opioid Dependence and Overdose after Urological Surgery.

PURPOSE: Effective pain management is a critical component of the perioperative process with opioids representing a mainstay of therapy. The opioid epidemic is a growing concern in the United States. The goal of this study was to quantify the risk of opioid dependence or overdose among patients undergoing urological surgery and to identify risk factors of opioid dependence or overdose. MATERIALS AND METHODS: We retrospectively reviewed data on urological surgery from 2007 to 2011. Data sources included the HCUP (Healthcare Cost and Utilization Project) inpatient, ambulatory surgery and emergency department data sets. Outcomes of postoperative opioid dependence and overdose were identified by previously validated ICD-9 codes. Multivariable logistic regression adjusted for surgical procedure was performed to identify predictors of opioid dependence or overdose following urological surgery. RESULTS: Overall 675,527 patients underwent urological surgery, of whom 0.09% were diagnosed with opioid dependence or overdose. Patients in whom opioid dependence or overdose developed were younger (median age 51 vs 62 years), carried nonprivate insurance (69.6% vs 66%), underwent an inpatient procedure (81.0% vs 42.4%) and had a longer length of stay (median 3 vs 0 days) and a history of depression (14.4% vs 3.4%) or chronic obstructive pulmonary disease (20.3% vs 8.9%, all p <0.001). On adjusted multivariable analysis these factors remained independent risk factors for opioid dependence or overdose. CONCLUSIONS: Postoperative opioid dependence or overdose affects 1 of 1,111 urological surgery patients. Risk factors for opioid dependence or overdose included younger age, inpatient surgery and increasing hospitalization duration, baseline depression, tobacco use and chronic obstructive pulmonary disease as well as insurance provider, including Medicaid, Medicare (age less than 65 years) and noninsured status.

Postoperative Urinary Retention is an Independent Predictor of Short-Term and Long-Term Future Bladder Outlet Procedure in Men.

PURPOSE: Postoperative urinary retention is a common complication across surgical specialties. To our knowledge no literature to date has examined postoperative urinary retention as a predictor of long-term receipt of surgery for bladder outlet obstruction. MATERIALS AND METHODS: We retrospectively reviewed the records of inpatients who underwent nonurological surgery in California between 2008 and 2010. Postoperative urinary retention during the index admission was identified, as was receipt of a bladder outlet procedure (transurethral prostate resection, prostate photoselective vaporization or suprapubic prostatectomy) at a subsequent encounter. Patients were matched using propensity scoring of demographics, comorbidities and surgery type. Adjusted Kaplan-Meier analysis was performed to determine the cumulative incidence of subsequent bladder outlet procedures by patient group, including group 1-age 60 years or greater and postoperative urinary retention, group 2-age 60 years or greater and no postoperative urinary retention, group 3-age less than 60 years and postoperative urinary retention, and group 4-age less than 60 years and no postoperative urinary retention. RESULTS: Of 769,141 eligible male patients postoperative urinary retention developed in 8,051 (1.1%). Following hospital discharge 1,855 patients (0.24%) underwent a bladder outlet procedure. Those treated with a bladder outlet procedure were significantly more likely to have experienced postoperative urinary retention during the index admission (6.3% vs 1.0%, p <0.001). On matched analysis the bladder outlet procedure rate at 3 years was 7.1%, 2.2%, 0.8% and 0.0% in groups 1, 2, 3 and 4, respectively. CONCLUSIONS: In men 60 years old or older postoperative urinary retention identified those with an increased incidence of bladder outlet procedures within 3 years. Men younger than 60 years had a low rate of subsequent bladder outlet procedures regardless of a postoperative urinary retention diagnosis.

Transient atrial fibrillation after open abdominal aortic revascularization surgery is associated with increased length of stay, mortality, and readmission rates.

BACKGROUND: It is well established that transient postoperative atrial fibrillation (TPAF) is associated with adverse postoperative outcomes after major cardiac and noncardiac operations. The purpose of this study was to elucidate the incidence, impact, and risk factors associated with the development of TPAF in patients undergoing revascularization surgery for occlusive diseases of the abdominal aorta and its branches (AAB). METHODS: By use of the Healthcare Cost and Utilization Project State Inpatient Database from Florida and California, patients who underwent open revascularization of AAB between 2006 and 2011 were identified. Patients diagnosed with aortic dissection or abdominal aortic aneurysm were excluded to limit the study cohort to include only patients with occlusive etiology. Also excluded were those with a pre-existing diagnosis of atrial fibrillation and those who underwent thoracic aortic repair and peripheral artery revascularization procedures. Multivariable logistic and linear regression analyses with treatment effects were conducted to analyze the association between TPAF and length of stay (LOS); the mortality rates at index admission, 1 month, and 1 year; and the readmission rates at 1 month and 1 year (adjusted for comorbidities and surgical and demographic factors). A backwards stepwise logistic regression model was built to identify predictors of TPAF. RESULTS: A total of 4462 patients were identified; 3253 underwent aortoiliac/femoral bypasses (72.9%), 1514 endarterectomies of AAB (33.9%), and 288 bypasses of AAB (6.5%). The incidence of TPAF was 2.4% (109 patients). Multivariate regression analysis with treatment effects showed that TPAF was associated with significantly increased LOS, mortality, and readmission rates. Factors identified as predictors of TPAF by backwards stepwise logistic regression modeling include electrolyte disorders, increasing age, and Charlson Comorbidity Index (C statistic = .69; accuracy = 58%). CONCLUSIONS: TPAF after revascularization of AAB is associated with increased LOS, inpatient mortality, 1-year mortality, and hospital readmissions. Strategies to identify patients at risk for development of TPAF and implementation of appropriate prophylactic measures may improve surgical outcomes and reduce cost of care.

Discordance between surgical care improvement project adherence and postoperative outcomes: implications for new Joint Commission standards.

BACKGROUND: Infectious (INF) and venous thromboembolism (VTE) complication rates are targeted by surgical care improvement project (SCIP) INF and SCIP VTE measures. We analyzed how adherence to SCIP INF and SCIP VTE affects targeted postoperative outcomes (wound complication [WC], deep vein thrombosis, and pulmonary embolism [PE]) using all-payer data. MATERIALS AND METHODS: A retrospective review (2007-2011) was conducted using Healthcare Cost and Utilization Project State Inpatient Database Florida and Medicare's Hospital Compare. The association between SCIP adherence rates and outcomes across 355 included surgical procedures was measured using multilevel mixed-effects linear regression models. RESULTS: One hundred sixty acute care hospitals and 779,922 patients were included. Over 5 y, SCIP INF-1, -2, and -3 adherence improved by 12.5%, 8.0%, and 20.9%, respectively, whereas postoperative WC rate decreased by 14.8%. When controlling for time, SCIP INF-1 adherence was associated with improvement of postoperative WC rates (ß = -0.0044, P = 0.005), whereas SCIP INF-2 adherence was associated with increased WCs (ß = 0.0031, P = 0.018). SCIP VTE-1, -2 adherence improved by 14.6% and 20.2%, respectively, whereas postoperative deep vein thrombosis rate increased by 7.1% and postoperative PE rate increased by 3.7%. SCIP VTE-1 and -2 adherence were both associated with increased postoperative PE when controlling for time (SCIP VTE-1: ß = 0.0019, P < 0.001; SCIP VTE-2: ß = 0.0015, P < 0.001). Readmission analysis found SCIP INF-1 adherence to be associated with improved 30-d WC rates when controlling for patient and hospital characteristics (ß = -0.0021, P = 0.032), whereas SCIP INF-3 adherence was associated with increased 30-d WC rates when controlling for time (ß = 0.0007, P = 0.04). CONCLUSIONS: Only SCIP INF-1 adherence was associated with improved outcomes. The Joint Commission has retired SCIP INF-2, -3, and SCIP VTE-2 and made SCIP INF-1 and VTE-1 reporting optional. Our study supports continued reporting of SCIP INF-1.

Urinary Exosomes: The Potential for Biomarker Utility, Intercellular Signaling and Therapeutics in Urological Malignancy.

PURPOSE: Exosomes are small secreted vesicles that contain proteins, mRNA and miRNA with the potential to alter signaling pathways in recipient cells. While exosome research has flourished, few publications have specifically considered the role of genitourinary cancer shed exosomes in urine, their implication in disease progression and their usefulness as noninvasive biomarkers. In this review we examined the current literature on the role of exosomes in intercellular communication and as biomarkers, and their potential as delivery vehicles for therapeutic applications in bladder, prostate and renal cancer. MATERIALS AND METHODS: We searched PubMed® and Google® with the key words prostate cancer, bladder cancer, kidney cancer, exosomes, microvesicles and urine. Relevant articles, including original research studies and reviews, were selected based on contents. A review of this literature was generated. RESULTS: Cancer exosomes can be isolated from urine using various techniques. Cancer cells have been found to secrete more exosomes than normal cells. These exosomes have a role in cellular communication by interacting with and depositing their cargo in target cells. Bladder, prostate and renal cancer exosomes have been shown to enhance migration, invasion and angiogenesis. These exosomes have also been shown to increase proliferation, confer drug resistance and promote immune evasion. CONCLUSIONS: Urinary exosomes can be isolated from bladder, kidney and prostate cancer. They serve as a potential reservoir for biomarker identification. Exosomes also have potential for therapeutics as siRNA or pharmacological agents can be loaded into exosomes.

Early Intervention during Acute Stone Admissions: Revealing "The Weekend Effect" in Urological Practice.

PURPOSE: Obstructing nephrolithiasis is a common condition that can require urgent intervention. In this study we analyze patient factors that contribute to delayed intervention during acute stone admission. MATERIALS AND METHODS: We retrospectively reviewed the HCUP SID (Healthcare Cost and Utilization Project State Inpatient Database) for Florida and California from 2007 to 2011. Patients who were admitted urgently with nephrolithiasis and an indication for decompression (urinary tract infection, acute renal insufficiency and/or sepsis) were included in the study. Intervention was timely or delayed, defined as a procedure that occurred within or after 48 hours, respectively. Adjusted multivariate models were fit to assess factors that predicted a delayed procedure as well as mortality. RESULTS: Overall 10,301 patients were admitted urgently for nephrolithiasis with indications for decompression. Early intervention occurred in 6,689 patients (65%) and was associated with a decrease in mortality (11, 0.16%), compared to delayed intervention (17 of 3,612, 0.47%, p=0.002). On multivariate analysis timely intervention significantly decreased the odds of inpatient mortality (OR 0.43, p=0.044). Weekend day admission significantly influenced time to intervention, decreasing patient odds of timely intervention by 26% (p <0.001). Other factors decreasing patient odds of timely intervention included nonCaucasian race and nonprivate insurance. Presenting medical diagnoses of urinary tract infection, sepsis and acute renal failure did not appear to influence time to intervention. CONCLUSIONS: Delayed operative intervention for acute nephrolithiasis admissions with indications for decompression results in increased patient mortality. Nonmedical factors such as the "weekend effect," race and insurance provider exerted the greatest influence on the timing of intervention.

Transient postoperative atrial fibrillation after abdominal aortic aneurysm repair increases mortality risk.

OBJECTIVE: The purpose of this study was to determine whether new-onset transient postoperative atrial fibrillation (TPAF) affects mortality rates after abdominal aortic aneurysm (AAA) repair and to identify predictors for the development of TPAF. METHODS: Patients who underwent open aortic repair or endovascular aortic repair for a principal diagnosis AAA were retrospectively identified using the Healthcare Cost and Utilization Project-State Inpatient Database (Florida) for 2007 to 2011 and monitored longitudinally for 1 year. Inpatient and 1-year mortality rates were compared between those with and without TPAF. TPAF was defined as new-onset atrial fibrillation that developed in the postoperative period and subsequently resolved in patients without a history of atrial fibrillation. Cox proportional hazards models, adjusted for age, gender, comorbidities, rupture status, and repair method, were used to assess 1-year survival. Predictive models were built with preoperative patient factors using Chi-squared Automatic Interaction Detector decision trees and externally validated on patients from California. RESULTS: A 3.7% incidence of TPAF was identified among 15,148 patients who underwent AAA repair. The overall mortality rate was 4.3%. The inpatient mortality rate was 12.3% in patients with TPAF vs 4.0% in those without TPAF. In the ruptured setting, the difference in mortality was similar between groups (33.7% vs 39.9%, P = .3). After controlling for age, gender, comorbid disease severity, urgency (ruptured vs nonruptured), and repair method, TPAF was associated with increased 1-year postoperative mortality (hazard ratio, 1.48; P < .001) and postdischarge mortality (hazard ratio, 1.56; P = .028). Chi-squared Automatic Interaction Detector-based models (C statistic = 0.70) were integrated into a Web-based application to predict an individual's probability of developing TPAF at the point of care. CONCLUSIONS: The development of TPAF is associated with an increased risk of mortality in patients undergoing repair of nonruptured AAA. Predictive modeling can be used to identify those patients at highest risk for developing TPAF and guide interventions to improve outcomes.

Microscopic origins of anisotropic active stress in motor-driven nematic liquid crystals.

The cytoskeleton, despite comprising relatively few building blocks, drives an impressive variety of cellular phenomena ranging from cell division to motility. These building blocks include filaments, motor proteins, and static crosslinkers. Outside of cells, these same components can form novel materials exhibiting active flows and nonequilibrium contraction or extension. While dipolar extensile or contractile active stresses are common in nematic motor-filament systems, their microscopic origin remains unclear. Here we study a minimal physical model of filaments, crosslinking motors, and static crosslinkers to dissect the microscopic mechanisms of stress generation in a two-dimensional system of orientationally aligned rods. We demonstrate the essential role of filament steric interactions which have not previously been considered to significantly contribute to active stresses. With this insight, we are able to tune contractile or extensile behavior through the control of motor-driven filament sliding and crosslinking. This work provides a roadmap for engineering stresses in active liquid crystals. The mechanisms we study may help explain why flowing nematic motor-filament mixtures are extensile while gelled systems are contractile.

Components of Hospital Perioperative Infrastructure Can Overcome the Weekend Effect in Urgent General Surgery Procedures.

OBJECTIVE: We hypothesized that perioperative hospital resources could overcome the "weekend effect" (WE) in patients undergoing emergent/urgent surgeries. SUMMARY BACKGROUND DATA: The WE is the observation that surgeon-independent patient outcomes are worse on the weekend compared with weekdays. The WE is often explained by differences in staffing and resources resulting in variation in care between the week and weekend. METHODS: Emergent/urgent surgeries were identified using the Healthcare Cost and Utilization Project State Inpatient Database (Florida) from 2007 to 2011 and linked to the American Hospital Association (AHA) Annual Survey Database to determine hospital level characteristics. Extended median length of stay (LOS) on the weekend compared with the weekdays (after controlling for hospital, year, and procedure type) was selected as a surrogate for WE. RESULTS: Included were 126,666 patients at 166 hospitals. A total of 17 hospitals overcame the WE during the study period. Logistic regression, controlling for patient characteristics, identified full adoption of electronic medical records (OR 4.74), home health program (OR 2.37), pain management program [odds ratio (OR) 1.48)], increased registered nurse-to-bed ratio (OR 1.44), and inpatient physical rehabilitation (OR 1.03) as resources that were predictors for overcoming the WE. The prevalence of these factors in hospitals exhibiting the WE for all 5 years of the study period were compared with those hospitals that overcame the WE (P < 0.001). CONCLUSIONS: Specific hospital resources can overcome the WE seen in urgent general surgery procedures. Improved hospital perioperative infrastructure represents an important target for overcoming disparities in surgical care.

Postoperative Atrial Fibrillation Predicts Long-Term Cardiovascular Events after Radical Cystectomy.

PURPOSE: Postoperative atrial fibrillation after radical cystectomy occurs in 2% to 8% of cases. Recent evidence suggests that transient postoperative atrial fibrillation leads to future cardiovascular events. The long-term cardiovascular implications of postoperative atrial fibrillation in patients undergoing radical cystectomy are largely unknown. MATERIALS AND METHODS: The Healthcare Cost and Utilization Project State Inpatient Databases for California and Florida were used to identify patients who underwent radical cystectomy between 2007 and 2010. After excluding patients with a history of atrial fibrillation, coronary artery disease and/or stroke, patients were matched using propensity scoring on age, race, insurance status and preexisting comorbidities. Adjusted Kaplan-Meier time-to-event analysis and Cox proportional hazards models were used to assess the effect of postoperative atrial fibrillation on cardiovascular events (acute myocardial infarction and stroke) during postoperative year 1. RESULTS: Radical cystectomy was performed in 4,345 patients who met the study inclusion criteria, of whom 210 (4.8%) had postoperative atrial fibrillation. There was a significantly higher cumulative incidence of cardiovascular events during the first postoperative year in patients in whom postoperative atrial fibrillation developed (24.8% vs 10.9%, adjusted log rank p=0.007). Cox proportional hazards regression demonstrated an increased risk of cardiovascular events in patients with postoperative atrial fibrillation (HR 10, p=0.02). CONCLUSIONS: Our results demonstrate that patients undergoing radical cystectomy in whom transient postoperative atrial fibrillation develops are at significantly increased risk for cardiovascular events in the first postoperative year. Physicians should be vigilant in assessing postoperative atrial fibrillation, even when transient, and establish appropriate followup given the increased risk of cardiovascular morbidity.

Multiscale polar theory of microtubule and motor-protein assemblies.

Microtubules and motor proteins are building blocks of self-organized subcellular biological structures such as the mitotic spindle and the centrosomal microtubule array. These same ingredients can form new "bioactive" liquid-crystalline fluids that are intrinsically out of equilibrium and which display complex flows and defect dynamics. It is not yet well understood how microscopic activity, which involves polarity-dependent interactions between motor proteins and microtubules, yields such larger-scale dynamical structures. In our multiscale theory, Brownian dynamics simulations of polar microtubule ensembles driven by cross-linking motors allow us to study microscopic organization and stresses. Polarity sorting and cross-link relaxation emerge as two polar-specific sources of active destabilizing stress. On larger length scales, our continuum Doi-Onsager theory captures the hydrodynamic flows generated by polarity-dependent active stresses. The results connect local polar structure to flow structures and defect dynamics.

Protein remote homology detection and structural alignment using deep learning.

Exploiting sequence-structure-function relationships in biotechnology requires improved methods for aligning proteins that have low sequence similarity to previously annotated proteins. We develop two deep learning methods to address this gap, TM-Vec and DeepBLAST. TM-Vec allows searching for structure-structure similarities in large sequence databases. It is trained to accurately predict TM-scores as a metric of structural similarity directly from sequence pairs without the need for intermediate computation or solution of structures. Once structurally similar proteins have been identified, DeepBLAST can structurally align proteins using only sequence information by identifying structurally homologous regions between proteins. It outperforms traditional sequence alignment methods and performs similarly to structure-based alignment methods. We show the merits of TM-Vec and DeepBLAST on a variety of datasets, including better identification of remotely homologous proteins compared with state-of-the-art sequence alignment and structure prediction methods.

Self-organized intracellular twisters.

Life in complex systems, such as cities and organisms, comes to a standstill when global coordination of mass, energy, and information flows is disrupted. Global coordination is no less important in single cells, especially in large oocytes and newly formed embryos, which commonly use fast fluid flows for dynamic reorganization of their cytoplasm. Here, we combine theory, computing, and imaging to investigate such flows in the Drosophila oocyte, where streaming has been proposed to spontaneously arise from hydrodynamic interactions among cortically anchored microtubules loaded with cargo-carrying molecular motors. We use a fast, accurate, and scalable numerical approach to investigate fluid-structure interactions of 1000s of flexible fibers and demonstrate the robust emergence and evolution of cell-spanning vortices, or twisters. Dominated by a rigid body rotation and secondary toroidal components, these flows are likely involved in rapid mixing and transport of ooplasmic components.