Adolescent Vaping-Associated Trauma in the Western United States.

INTRODUCTION: Electronic cigarettes (e-cigarettes) are handheld, battery-powered vaporizing devices. It is estimated that more than 25% of youth have used these devices recreationally. While vaping-associated lung injury is an increasingly recognized risk, little is known about the risk of traumatic injuries associated with e-cigarette malfunction. METHODS: A multi-institutional retrospective study was performed by querying the electronic health records at nine children's hospitals. Patients who sustained traumatic injuries while vaping from January 2016 through December 2019 were identified. Patient demographics, injury characteristics, and the details of trauma management were reviewed. RESULTS: 15 children sustained traumatic injuries due to e-cigarette explosion. The median age was 17 y (range 13-18). The median injury severity score was 2 (range 1-5). Three patients reported that their injury coincided with their first vaping experience. Ten patients required hospital admission, three of whom required intensive care unit admission. Admitted patients had a median length of stay of 3 d (range 1-6). The injuries sustained were: facial burns (6), loss of multiple teeth (5), thigh and groin burns (5), hand burns (4), ocular burns (4), a radial nerve injury, a facial laceration, and a mandible fracture. Six children required operative intervention, one of whom required multiple operations for a severe hand injury. CONCLUSIONS: In addition to vaping-associated lung injury, vaping-associated traumatic injuries are an emerging and worrisome injury pattern sustained by adolescents in the United States. This report highlights another means by which e-cigarettes pose an increasing risk to a vulnerable youth population.

An Unusual Cause for Intermittent Stridor and Dysphagia in an Infant.

Stridor is a common presenting symptom in young children and is produced by turbulent flow through the upper airway or trachea. In children under 12 months of age, stridor is commonly caused by laryngomalacia, tracheomalacia, croup, airway foreign body, and/or retropharyngeal abscess. In atypical presentations of stridor, soft tissue neck radiographs can be helpful to determine the underlying etiology. Occasionally, children will require bronchoscopy to determine the etiology and treatment.

Decision-Making in Pleural Drainage Following Lung Resection in Children: A Western Pediatric Surgery Research Consortium Survey.

INTRODUCTION: Studies of adults undergoing lung resection indicated that selective omission of pleural drains is safe and advantageous. Significant practice variation exists for pleural drainage practices for children undergoing lung resection. We surveyed pediatric surgeons in a 10-hospital research consortium to understand decision-making for placement of pleural drains following lung resection in children. METHODS: Faculty surgeons at the 10 member institutions of the Western Pediatric Surgery Research Consortium completed questionnaires using a REDCap survey platform. Descriptive statistics and bivariate analyses were used to characterize responses regarding indications and management of pleural drains following lung resection in pediatric patients. RESULTS: We received 96 responses from 109 surgeons (88 %). Most surgeons agreed that use of a pleural drain after lung resection contributes to post-operative pain, increases narcotic use, and prolongs hospitalization. Opinions varied around the immediate use of suction compared to water seal, and half routinely completed a water seal trial prior to drain removal. Surgeons who completed fellowship within the past 10 years left a pleural drain after wedge resection in 45 % of cases versus 78 % in those who completed fellowship more than 10 years ago (p = 0.001). The mean acceptable rate of unplanned post-operative pleural drain placement when pleural drainage was omitted at index operation was 6.3 % (±4.6 %). CONCLUSIONS: Most pediatric surgeons use pleural drainage following lung resection, with recent fellowship graduates more often omitting it. Future studies of pleural drain omission demonstrating low rates of unplanned postoperative pleural drain placement may motivate practice changes for children undergoing lung resection. LEVEL OF EVIDENCE: V.

A practical mortality risk score for emergent colectomy.

BACKGROUND: Critically ill patients requiring emergent colectomy have significant mortality risk. OBJECTIVE: A national administrative database was used to compose a simple scoring scheme for predicting in-hospital mortality risk. DESIGN: The 2007 to 2009 Nationwide Inpatient Sample was queried to identify patients requiring nonelective colectomy. Multivariable binary logistic regression analysis was used to identify predictors that increased mortality. Each predictor was given a point value, based on the corresponding logit, the sum of which constituted a risk score. The scoring system was tested by using k-partitions cross-validation. SETTINGS: This study is based on database analysis. PATIENTS: A total of 338,348 cases were identified. Mean age was 64, and 53% of the patients were women. MAIN OUTCOME MEASURES: The primary outcomes measured were mortality and risk score development. RESULTS: The overall mortality risk was 9%. Regression analysis identified the following risk factors and assigned points: acute renal failure (6), hemodialysis (6), age >65 (4), peripheral vascular disease (4), myocardial infarction (4), chronic obstructive pulmonary disease (2), cardiac arrhythmia (1), and congestive heart failure (1). The maximum score observed was 26 (of a possible 28), which corresponded to 100% mortality. Receiver operator characteristic analysis showed an area under the curve of 0.81. LIMITATIONS: This study was limited because of its retrospective nature, and because it used database data with variability in coding among participating institutions. CONCLUSIONS: With the use of a simple 8-variable scoring system, inpatient mortality estimates can be made for patients requiring emergent colectomy. When used judiciously, it can be used as a tool when counseling patients and family both before and after surgery.

Transfer status is a risk factor for increased in-hospital mortality in patients with diverticular hemorrhage.

PURPOSE: Gastrointestinal tract hemorrhage is a common problem accounting for approximately 1 % of hospital admissions. It is estimated that one third of the episodes of lower gastrointestinal hemorrhage are secondary to diverticular disease. Inter-institutional transfer has been associated with delay in care and increased in-hospital mortality. We hypothesized that patients with diverticular hemorrhage that were transferred from an acute care hospital to tertiary care institutions have increased in-hospital morbidity and mortality when compared to primarily admitted patients. MATERIALS AND METHODS: We performed a retrospective analysis of the Nationwide Inpatient Sample for the year 2008. Patients with a primary discharge diagnosis of diverticular hemorrhage were selected. Multivariate logistic regression was used to identify the relationship between transfer status and in-hospital mortality. RESULTS: A total of 99,415 hospitalizations for diverticular hemorrhage were identified. Transferred patients had higher in-hospital mortality rates compared to primarily admitted patients (3.5 vs. 1.8 %, p < 0.001), as well as increased length of stay (8.4 vs. 5.4 days, p < 0.001) and a higher rate of total abdominal colectomy (1.2 vs. 0.6 %, p < 0.001). Multivariate analysis indicated that transfer status was associated with increased in-hospital mortality [OR 1.8, 95 % CI 1.5-2.8, p < 0.001]. CONCLUSIONS: Inter-institutional transfer for diverticular bleeding is associated with increased in-hospital mortality, increased total abdominal colectomy rate, as well as increased economic burden including mean length of stay and total hospital charges. Further prospective studies are needed to analyze the clinical information of patients requiring transfer to another hospital in order to identify those patients who would truly benefit from inter-institutional transfer.

Software Application Profile: dynamicLM-a tool for performing dynamic risk prediction using a landmark supermodel for survival data under competing risks.

MOTIVATION: Providing a dynamic assessment of prognosis is essential for improved personalized medicine. The landmark model for survival data provides a potentially powerful solution to the dynamic prediction of disease progression. However, a general framework and a flexible implementation of the model that incorporates various outcomes, such as competing events, have been lacking. We present an R package, dynamicLM, a user-friendly tool for the landmark model for the dynamic prediction of survival data under competing risks, which includes various functions for data preparation, model development, prediction and evaluation of predictive performance. IMPLEMENTATION: dynamicLM as an R package. GENERAL FEATURES: The package includes options for incorporating time-varying covariates, capturing time-dependent effects of predictors and fitting a cause-specific landmark model for time-to-event data with or without competing risks. Tools for evaluating the prediction performance include time-dependent area under the ROC curve, Brier Score and calibration. AVAILABILITY: Available on GitHub [https://github.com/thehanlab/dynamicLM].

Cryoablation in 350 Nuss Procedures: Evolution of Hospital Length of Stay and Opioid Use.

INTRODUCTION: Current studies show cryoablation decreases opioid requirements and lengths of stay (LOS) in patients undergoing the Nuss procedure for pectus excavatum. This study evaluated the relationship between cryoablation and clinical outcomes for the Nuss procedure. METHODS: A retrospective single-center chart review was performed on patients undergoing the Nuss procedure with intercostal cryoablation from December 2017-August 2021. Demographics, hospital course, and postoperative complications were abstracted. To evaluate the evolution of outcomes over time, the earliest quarter (Q1) of cryoablation patients was compared to the last quarter (Q4). RESULTS: Over 45 months, 350 Nuss procedures with cryoablation were performed. The mean age at operation was 15.7 ± 2.3 years with an average Haller Index of 5.4 ± 4.2. The mean operative time was 136 ± 40.5 minutes. On average, patients used 2.8 ± 2.5 OME/kg of opioid in hospital with a LOS of 2.7 ± 1.1 days. The Q4 patients were discharged 1.3 days earlier (p<0.05) than Q1 patients, with 80% of Q4 discharged by postoperative day #2 vs. 23% in Q1 (p<0.05). Q4 patients received 74% (p<0.05) less opioid in hospital and 21% (p<0.05) less on discharge. Within 90 days postoperatively, complication rates (chest tube placement, wound infection, readmission, neuropathic pain) were similar. Only two patients (0.6%) required reoperation for bar migration/slippage. CONCLUSION: With increased experience, cryoablation for the Nuss procedure decreased opioid use by 74% and was associated with 80% of patients achieving early discharge. Major complication rates were not increased. Cryoablation can be successfully implemented as an effective method of postoperative analgesia. LEVEL OF EVIDENCE: Level III.

Gravitational effects on intraocular pressure and ocular perfusion pressure.

Changes in the gravitational vector by postural changes or weightlessness induce fluid shifts, impacting ocular hemodynamics and regional pressures. This investigation explores the impact of changes in the direction of the gravitational vector on intraocular pressure (IOP), mean arterial pressure at eye level (MAPeye), and ocular perfusion pressure (OPP), which is critical for ocular health. Thirteen subjects underwent 360° of tilt (including both prone and supine positions) at 15° increments. At each angle, steady-state IOP and MAPeye were measured, and OPP calculated as MAPeye - IOP. Experimental data were also compared to a six-compartment lumped-parameter model of the eye. Mean IOP, MAPeye, and OPP significantly increased from 0° supine to 90° head-down tilt (HDT) by 20.7 ± 1.7 mmHg (P < 0.001), 38.5 ± 4.1 mmHg (P < 0.001), and 17.4 ± 3.2 mmHg (P < 0.001), respectively. Head-up tilt (HUT) significantly decreased OPP by 16.5 ± 2.5 mmHg (P < 0.001). IOP was significantly higher in prone versus supine position for much of the tilt range. Our study indicates that OPP is highly gravitationally dependent. Specifically, data show that MAPeye is more gravitationally dependent than IOP, thus causing OPP to increase during HDT and to decrease during HUT. In addition, IOP was elevated in prone position compared with supine position due to the additional hydrostatic column between the base of the rostral globe to the mid-coronal plane, supporting the notion that hydrostatic forces play an important role in ocular hemodynamics. Changes in OPP as a function of changes in gravitational stress and/or weightlessness may play a role in the pathogenesis of spaceflight-associated neuro-ocular syndrome.NEW & NOTEWORTHY Maintaining appropriate ocular perfusion pressure (OPP) is critical for ocular health. We measured the relative changes in intraocular and mean arterial pressures during 360° tilt and calculated OPP, which was elevated during head-down tilt and decreased during head-up tilt. Experimental data are also explained by our computational model. We demonstrate that OPP is more gravitationally dependent than previously recognized and may be a factor in the overall patho-etiology behind the weightlessness-induced spaceflight-associated neuro-ocular syndrome.

Mobile Protons Limit the Stability of Salt Bridges in the Gas Phase: Implications for the Structures of Electrosprayed Protein Ions.

Electrosprayed protein ions can retain native-like conformations. The intramolecular contacts that stabilize these compact gas-phase structures remain poorly understood. Recent work has uncovered abundant salt bridges in electrosprayed proteins. Salt bridges are zwitterionic BH+/A- contacts. The low dielectric constant in the vacuum strengthens electrostatic interactions, suggesting that salt bridges could be a key contributor to the retention of compact protein structures. A problem with this assertion is that H+ are mobile, such that H+ transfer can convert salt bridges into neutral B0/HA0 contacts. This possible salt bridge annihilation puts into question the role of zwitterionic motifs in the gas phase, and it calls for a detailed analysis of BH+/A- versus B0/HA0 interactions. Here, we investigate this issue using molecular dynamics (MD) simulations and electrospray experiments. MD data for short model peptides revealed that salt bridges with static H+ have dissociation energies around 700 kJ mol-1. The corresponding B0/HA0 contacts are 1 order of magnitude weaker. When considering the effects of mobile H+, BH+/A- bond energies were found to be between these two extremes, confirming that H+ migration can significantly weaken salt bridges. Next, we examined the protein ubiquitin under collision-induced unfolding (CIU) conditions. CIU simulations were conducted using three different MD models: (i) Positive-only runs with static H+ did not allow for salt bridge formation and produced highly expanded CIU structures. (ii) Zwitterionic runs with static H+ resulted in abundant salt bridges, culminating in much more compact CIU structures. (iii) Mobile H+ simulations allowed for the dynamic formation/annihilation of salt bridges, generating CIU structures intermediate between scenarios (i) and (ii). Our results uncover that mobile H+ limit the stabilizing effects of salt bridges in the gas phase. Failure to consider the effects of mobile H+ in MD simulations will result in unrealistic outcomes under CIU conditions.

Robust Performance of Potentially Functional SNPs in Machine Learning Models for the Prediction of Atorvastatin-Induced Myalgia.

Statins can cause muscle symptoms resulting in poor adherence to therapy and increased cardiovascular risk. We hypothesize that combinations of potentially functional SNPs (pfSNPs), rather than individual SNPs, better predict myalgia in patients on atorvastatin. This study assesses the value of potentially functional single nucleotide polymorphisms (pfSNPs) and employs six machine learning algorithms to identify the combination of SNPs that best predict myalgia. Methods: Whole genome sequencing of 183 Chinese, Malay and Indian patients from Singapore was conducted to identify genetic variants associated with atorvastatin induced myalgia. To adjust for confounding factors, demographic and clinical characteristics were also examined for their association with myalgia. The top factor, sex, was then used as a covariate in the whole genome association analyses. Variants that were highly associated with myalgia from this and previous studies were extracted, assessed for potential functionality (pfSNPs) and incorporated into six machine learning models. Predictive performance of a combination of different models and inputs were compared using the average cross validation area under ROC curve (AUC). The minimum combination of SNPs to achieve maximum sensitivity and specificity as determined by AUC, that predict atorvastatin-induced myalgia in most, if not all the six machine learning models was determined. Results: Through whole genome association analyses using sex as a covariate, a larger proportion of pfSNPs compared to non-pf SNPs were found to be highly associated with myalgia. Although none of the individual SNPs achieved genome wide significance in univariate analyses, machine learning models identified a combination of 15 SNPs that predict myalgia with good predictive performance (AUC >0.9). SNPs within genes identified in this study significantly outperformed SNPs within genes previously reported to be associated with myalgia. pfSNPs were found to be more robust in predicting myalgia, outperforming non-pf SNPs in the majority of machine learning models tested. Conclusion: Combinations of pfSNPs that were consistently identified by different machine learning models to have high predictive performance have good potential to be clinically useful for predicting atorvastatin-induced myalgia once validated against an independent cohort of patients.

Dose-Response Relationship Between Intracoronary Acetylcholine and Minimal Lumen Diameter in Coronary Endothelial Function Testing of Women and Men With Angina and No Obstructive Coronary Artery Disease.

BACKGROUND: Intracoronary acetylcholine (Ach) provocation testing is the gold standard for assessing coronary endothelial function. However, dosing regimens of Ach are quite varied in the literature, and there are limited data evaluating the optimal dose. We evaluated the dose-response relationship between Ach and minimal lumen diameter (MLD) by sex and studied whether incremental intracoronary Ach doses given during endothelial function testing improve its diagnostic utility. METHODS: We evaluated 65 men and 212 women with angina and no obstructive coronary artery disease who underwent endothelial function testing using the highest tolerable dose of intracoronary Ach, up to 200 µg. Epicardial endothelial dysfunction was defined as a decrease in MLD >20% after intracoronary Ach by quantitative coronary angiography. We used a linear mixed effects model to evaluate the dose-response relationship. Deming regression analysis was done to compare the %MLD constriction after incremental doses of intracoronary Ach. RESULTS: The mean age was 53.5 years. Endothelial dysfunction was present in 186 (68.1%). Among men with endothelial dysfunction, there was a significant decrease in MLD/10 µg of Ach at doses above 50 µg and 100 µg, while this decrease in MLD was not observed in women (P<0.001). The %MLD constriction at 20 µg versus 50 µg and 50 µg versus 100 µg were not equivalent while the %MLD constriction at 100 µg versus 200 µg were equivalent. CONCLUSIONS: Women and men appear to have different responses to Ach during endothelial function testing. In addition to having a greater response to intracoronary Ach at all doses, men also demonstrate an Ach-MLD dose-response relationship with doses up to 200 µg, while women have minimal change in MLD with doses above 50 µg. An incremental dosing regimen during endothelial function testing appears to improve the diagnostic utility of the test and should be adjusted based on the sex of the patient.

Testing the Robustness of Solution Force Fields for MD Simulations on Gaseous Protein Ions.

It is believed that electrosprayed proteins and protein complexes can retain solution-like conformations in the gas phase. However, the lack of high-resolution structure determination methods for gaseous protein ions implies that their properties remain poorly understood. Many practitioners tackle this difficulty by complementing mass spectrometry-based experiments with molecular dynamics (MD) simulations. It is a potential problem that the standard MD force fields used for this purpose (such as OPLS-AA/L and CHARMM) were optimized for solution conditions. The question whether these force fields produce meaningful gas-phase data has received surprisingly little attention. Standard force fields are overpolarized to account for an aqueous environment, i.e., atomic charges and intramolecular dipole moments are ∼20% larger than predicted by gas-phase ab initio methods. Here, we examined the implications of this overpolarization by conducting a series of MD simulations on electrosprayed proteins. Force fields were modified via a charge scaling factor (CSF), while ensuring that the net protein charge remained unchanged. CSF = 0.8 should roughly eliminate water-associated overpolarization. Gas-phase CHARMM simulations on myoglobin with CSF = 0.8 and with unmodified parameters (CSF = 1) yielded similar results, preserving a compact structure that was consistent with ion mobility experiments. Major structural changes caused by weakened charge-dipole and dipole-dipole contacts occurred only when lowering CSF to physically unreasonable values (0.5 and 0.1). Similar results were obtained in mobile-proton OPLS-AA/L simulations on the collision-induced dissociation of transthyretin. Our data support the view that gas-phase MD simulations with standard (solution) force fields are suitable for modeling gaseous protein ions in a semiquantitative manner. Although this is welcome news for the mass spectrometry community, it is hoped that dedicated gas-phase MD force fields will become available in the near future.

A Rare Case of Thoracoschisis.

A term male baby, after delivery, was found to have a 3-centimeter beefy-red mass protruding from the left chest wall, adjacent to the left nipple. Radiological imaging suggested it's origin from the left lateral liver segment. A diagnostic laparoscopy confirmed the isolated connection to the liver, elevated left hemidiaphragm, and protrusion between the ribs. The mass was excised using electrocautery, and pathologic examination showed normal liver tissue.

Micro- and nano-patterned conductive graphene-PEG hybrid scaffolds for cardiac tissue engineering.

A lack of electrical conductivity and structural organization in currently available biomaterial scaffolds limits their utility for generating physiologically representative models of functional cardiac tissue. Here we report on the development of scalable, graphene-functionalized topographies with anisotropic electrical conductivity for engineering the structural and functional phenotypes of macroscopic cardiac tissue constructs. Guided by anisotropic electroconductive and topographic cues, the tissue constructs displayed structural property enhancement in myofibrils and sarcomeres, and exhibited significant increases in the expression of cell-cell coupling and calcium handling proteins, as well as in action potential duration and peak calcium release.

Preventable pediatric intensive care unit admissions over a 13-year period at a level 1 pediatric trauma center.

BACKGROUND: No formal criteria exist to determine the need for admission of injured children to the pediatric intensive care unit. Our objective was to analyze trauma patient admissions to the PICU at a level 1 pediatric trauma center. METHODS: The trauma registry was analyzed between 2002 and 2015. A preventable PICU admission was defined as a child discharged home or transferred out of the PICU within 30h without surgical intervention, blood transfusion, or ventilator support. RESULTS: Of 16,209 children, 19% were admitted to the PICU: mean age 7.3years, median ISS 17, and overall mortality 7%. Per our definition, 36% were preventable PICU admissions of which 83% suffered a head injury. The preventable admissions were younger (6.9 vs. 7.6years, p<0.001) with a lower median ISS (16 vs. 21, p<0.001), shorter median PICU LOS (17 vs. 41h, p<0.001) and shorter median hospital LOS (51 vs. 121h, p<0.001). These admissions resulted in total facility charges of $9,981,454.76 with 54% produced by children with an isolated head injury. CONCLUSIONS: A significant number of children admitted to our PICU were classified as preventable. They carry a substantial economic burden to the health care system with an overutilization of resources. Methods to limit such admissions should be actively pursued.

Preventable transfers in pediatric trauma: A 10-year experience at a level I pediatric trauma center.

BACKGROUND: Injured children are often treated at one facility then transferred to another that specializes in pediatric trauma care. The purpose of this study was to identify and characterize potentially preventable transfers (PT) to a freestanding level-I pediatric trauma center. METHODS: Children with traumatic injuries transferred between 2003 and 2013 were retrospectively analyzed. A PT was defined as a child who was discharged within 36hours of arrival without surgical intervention or advanced imaging studies. RESULTS: During this period, 6380 children were transferred, with head injury being the most common injury. 61% had CT imaging performed before transfer. The mean age was 6.9years, mean injury severity score (ISS) 10.4, and median transfer distance 37miles. 27% of these transfers were classified as PT. Air transport was used in 15% at mean charge of $18,574. 29% were discharged from the emergency department. When compared, PTs were younger (6.0 vs. 7.2years, p<0.001), with lower median ISS (5 vs. 9, p<0.001), shorter median LOS (15 vs. 43.6hours, p<0.001), and less PICU admissions (6% vs. 34%, p<0.001). CONCLUSION: A significant number of pediatric trauma transfers can be classified as preventable. Reducing preventable transfers could offer opportunities for improving value in a trauma care system.

Combined effects of substrate topography and stiffness on endothelial cytokine and chemokine secretion.

Endothelial physiology is regulated not only by humoral factors, but also by mechanical factors such as fluid shear stress and the underlying cellular matrix microenvironment. The purpose of the present study was to examine the effects of matrix topographical cues on the endothelial secretion of cytokines/chemokines in vitro. Human endothelial cells were cultured on nanopatterned polymeric substrates with different ratios of ridge to groove widths (1:1, 1:2, and 1:5) and with different stiffnesses (6.7 MPa and 2.5 GPa) in the presence and absence of 1.0 ng/mL TNF-α. The levels of cytokines/chemokines secreted into the conditioned media were analyzed with a multiplexed bead-based sandwich immunoassay. Of the nanopatterns tested, the 1:1 and 1:2 type patterns were found to induce the greatest degree of endothelial cell elongation and directional alignment. The 1:2 type nanopatterns lowered the secretion of inflammatory cytokines such as IL-1ß, IL-3, and MCP-1, compared to unpatterned substrates. Additionally, of the two polymers tested, it was found that the stiffer substrate resulted in significant decreases in the secretion of IL-3 and MCP-1. These results suggest that substrates with specific extracellular nanotopographical cues or stiffnesses may provide anti-atherogenic effects like those seen with laminar shear stresses by suppressing the endothelial secretion of cytokines and chemokines involved in vascular inflammation and remodeling.

Induction of human embryonic and induced pluripotent stem cells into urothelium.

In vitro generation of human urothelium from stem cells would be a major advancement in the regenerative medicine field, providing alternate nonurologic and/or nonautologous tissue sources for bladder grafts. Such a model would also help decipher the mechanisms of urothelial differentiation and would facilitate investigation of deviated differentiation of normal progenitors into urothelial cancer stem cells, perhaps elucidating areas of intervention for improved treatments. Thus far, in vitro derivation of urothelium from human embryonic stem cells (hESCs) or human induced pluripotent stem (hiPS) cells has not been reported. The goal of this work was to develop an efficient in vitro protocol for the induction of hESCs into urothelium through an intermediary definitive endoderm step and free of matrices and cell contact. During directed differentiation in a urothelial-specific medium ("Uromedium"), hESCs produced up to 60% urothelium, as determined by uroplakin expression; subsequent propagation selected for 90% urothelium. Alteration of the epithelial and mesenchymal cell signaling contribution through noncell contact coculture or conditioned media did not enhance the production of urothelium. Temporospatial evaluation of transcription factors known to be involved in urothelial specification showed association of IRF1, GET1, and GATA4 with uroplakin expression. Additional hESC and hiPS cell lines could also be induced into urothelium using this in vitro system. These results demonstrate that derivation and propagation of urothelium from hESCs and hiPS cells can be efficiently accomplished in vitro in the absence of matrices, cell contact, or adult cell signaling and that the induction process appears to mimic normal differentiation.