Tailored Treatment Based on Helicobacter pylori Genetic Markers of Resistance Is Associated With Higher Eradication Success.

INTRODUCTION: Increasing antimicrobial resistance with Helicobacter pylori infection has focused efforts to tailor eradication therapy based on identifying genetic markers of resistance to predict antimicrobial susceptibility. METHODS: In this retrospective study, we report the effect of routine inclusion of antimicrobial susceptibility testing and recommendations for eradication therapy with gastric specimens with H. pylori . RESULTS: The use of a recommended treatment regimen based on genetic markers of resistance was associated with an 84% rate of eradication success and 4.4 greater odds of eradication relative to unrecommended treatment. DISCUSSION: This is the first study describing the use of H. pylori genetic resistance testing as standard of care.

Incidence of sedation-related adverse events during ERCP with anesthesia assistance: a multicenter observational study.

BACKGROUND AND AIMS: Anesthesia assistance is commonly used for ERCP. General anesthesia (GA) may provide greater airway protection but may lead to hypotension. We aimed to compare GA versus sedation without planned intubation (SWPI) on the incidence of hypoxemia and hypotension. We also explored risk factors for conversion from SWPI to GA. METHODS: This observational study used data from the Multicenter Perioperative Outcomes Group. Adults with American Society of Anesthesiologists physical status class I to IV undergoing ERCP between 2006 and 2019 were included. We compared GA and SWPI on incidence of hypoxemia (oxygen saturation <90% for ≥3 minutes) and hypotension (mean arterial pressure <65 mm Hg for ≥5 minutes) using joint hypothesis testing. The association between anesthetic approach and outcomes was assessed using logistic regression. The noninferiority delta for hypoxemia and hypotension was an odds ratio of 1.20. One approach was deemed better if it was noninferior on both outcomes and superior on at least 1 outcome. To explore risk factors associated with conversion from SWPI to GA, we constructed a logistic regression model. RESULTS: Among 61,735 cases from 42 institutions, 38,830 (63%) received GA and 22,905 (37%) received SWPI. The GA group had 1.27 times (97.5% confidence interval, 1.19-1.35) higher odds of hypotension but .71 times (97.5% confidence interval, .63-.80) lower odds of hypoxemia. Neither group was noninferior to the other on both outcomes. Conversion from SWPI to GA occurred in 6.5% of cases and was associated with baseline comorbidities and higher institutional procedure volume. CONCLUSIONS: GA for ERCP was associated with less hypoxemia, whereas SWPI was associated with less hypotension. Neither approach was better on the combined incidence of hypotension and hypoxemia.

Receipt of Serial Endoscopy Procedures Prior to Esophageal Adenocarcinoma Diagnosis Is Associated with Better Survival.

BACKGROUND: The poor prognosis of esophageal adenocarcinoma (EAC) has focused efforts on early detection by serial endoscopic surveillance of Barrett's esophagus (BE). Previously, we reported that receipt of endoscopy before EAC diagnosis was associated with improved survival. AIM: We aimed to refine our previous analysis, assessing surveillance as measured by performance of serial endoscopy before EAC diagnosis and evaluating its association with stage and survival. METHODS: A retrospective cohort study was performed using the Surveillance, Epidemiology and End Results-Medicare database. Patients aged ≥ 70 years with EAC diagnosed during 1998-2009 were identified. Diagnosis with BE and receipt of ≥ 2 upper endoscopic procedures within 5 years before cancer diagnosis were identified. We compared a reference group not receiving serial endoscopy to 3 patterns based on ≥ 2 endoscopy dates relative to a timepoint 2 years before cancer diagnosis: "remote," "recent," and "sustained." RESULTS: Among 5532 patients, 28% (n = 1,575) had localized stage. Thirteen percent (n = 703) received ≥ 2 endoscopic procedures before cancer diagnosis: 224, 298, and 181 in the "recent," "remote," and "sustained" groups. Serial endoscopy and prior BE were associated with localized stage ("sustained" group OR 2.95, 95% confidence interval [CI] 2.07, 4.19; prior BE OR 2.68, 95% CI 2.03, 3.56). Serial endoscopy was associated with improved survival even with adjustment for lead time bias ("sustained" group HR 0.45, 95% CI 0.37, 0.55) and length time bias. CONCLUSIONS: Sustained endoscopy was associated with earlier stage and improved survival. These results support the role of sustained surveillance in early detection of EAC.

The Intestinal Microbiome and Cystic Fibrosis Transmembrane Conductance Regulator Modulators: Emerging Themes in the Management of Gastrointestinal Manifestations of Cystic Fibrosis.

PURPOSE OF REVIEW: While commonly associated with pulmonary manifestations, cystic fibrosis (CF) is a systemic disease with wide-ranging effects on the gastrointestinal (GI) tract. This article reviews major recent updates in gastroenterological CF care and research. RECENT FINDINGS: The high burden of GI symptoms in CF has led to recent studies assessing GI-specific symptom questionnaires and scoring systems. Intestinal dysbiosis potentially contributes to gastrointestinal symptoms in patients with CF and an increased risk of gastrointestinal cancers in CF. An increased incidence of colorectal cancer (CRC) has led to CF-specific CRC screening and surveillance recommendations. Pharmacologic therapies targeting specific cystic fibrosis transmembrane conductance regulator (CFTR) mutations have shown promise in treating GI manifestations of CF. New research has highlighted the importance of intestinal dysbiosis in CF. Future studies should assess whether CFTR modulators affect the gut microbiome and whether altering the gut microbiome will impact GI symptoms and GI cancer risk.

Effects of spatially-varying substrate anchoring on instabilities and dewetting of thin nematic liquid crystal films.

Partially wetting nematic liquid crystal (NLC) films on substrates are unstable to dewetting-type instabilities due to destabilizing solid/NLC interaction forces. These instabilities are modified by the nematic nature of the films, which influences the effective solid/NLC interaction. In this work, we focus on the influence of imposed substrate anchoring on the instability development. The analysis is carried out within a long-wave formulation based on the Leslie-Ericksen description of NLC films. Linear stability analysis of the resulting equations shows that some features of the instability, such as emerging wavelengths, may not be influenced by the imposed substrate anchoring. Going further into the nonlinear regime, considered via large-scale GPU-based simulations, shows however that nonlinear effects may play an important role, in particular in the case of strong substrate anchoring anisotropy. Our simulations show that instability of the film develops in two stages: the first stage involves formation of ridges that are perpendicular to the local anchoring direction; and the second involves breakup of these ridges and formation of drops, whose final distribution is influenced by the anisotropy imposed by the substrate. Finally, we show that imposing more complex substrate anisotropy patterns allows us to reach basic understanding of the influence of substrate-imposed defects in director orientation on the instability evolution.

Outcomes after endoscopic versus surgical therapy for early esophageal cancers in an older population.

BACKGROUND AND AIMS: Endoscopic treatment of early esophageal cancer provides an alternative to esophagectomy, which older patients may not tolerate. Population-based data regarding short-term outcomes and recurrence after endoscopic treatment for esophageal cancer are limited. We compared short-term outcomes, treated recurrence, and survival after endoscopic versus surgical therapy for early esophageal cancers in an older population. METHODS: We conducted a retrospective cohort study identifying patients aged ≥66 years with Tis or T1a tumors without nodal involvement diagnosed from 1994 to 2011 from the linked Surveillance, Epidemiology, and End Results (SEER)-Medicare database. RESULTS: Of 2193 patients, 41% (n = 893) underwent esophagectomy, and 12% (n = 255) underwent endoscopic treatment within 6 months of diagnosis. Those treated endoscopically were older and more likely to have a Charlson comorbidity score ≥2. A composite endpoint, hospitalization and/or adverse events at 60 days, was higher in surgical patients than in the endoscopic treatment group (30% vs 12%; P < .001). In a Cox model stratified by histology, adjusting for other factors, endoscopic treatment was associated with improved 2-year survival (hazard ratio 0.51; 95% CI, 0.36-0.73). CONCLUSIONS: In this older population, a composite short-term endpoint was worse in the surgical group. Endoscopic treatment was associated with improved survival through 2 years. These results suggest that endoscopic treatment is a reasonable approach for early esophageal cancers in the elderly.

Serum 25-Hydroxyvitamin D Levels and the Risk of Dysplasia and Esophageal Adenocarcinoma in Patients with Barrett's Esophagus.

BACKGROUND: To date, there are no studies reporting an association between vitamin D and Barrett's esophagus (BE), the precursor for esophageal adenocarcinoma (EAC). AIMS: Our aim was to study the association between serum 25-hydroxyvitamin D (25(OH)D) levels and prevalence and incidence of dysplasia/EAC in BE. METHODS: Patients from our BE Registry cohort seen between 2000 and 2012 who had serum 25(OH)D levels measured were included. Age, gender, race, BE length, hiatal hernia size, and histological findings were recorded. Patients without high-grade dysplasia (HGD)/EAC at or within 1 year of index biopsy and who had follow-up endoscopies and 25(OH)D levels were studied for incidence of dysplasia/EAC. RESULTS: Among 429 patients with BE, the mean 25(OH)D level was 72 ± 31.2 nmol/L. Hundred and one (23.6 %) patients had deficiency (<50 nmol/L), 149 (34.7 %) had insufficiency (50-74.9 nmol/L), and 179 (41.7 %) had normal levels of 25(OH)D. There was no association between serum 25(OH)D levels and dysplasia (p = 0.90). In the incidence cohort of 246 patients with median follow-up of 46 months, there were 34 cases of low-grade dysplasia, 12 of HGD, and 5 of EAC. Change in 25(OH)D levels did not impact progression to dysplasia/EAC (every 5 nmol/L increase from baseline, hazard ratio 0.98; p = 0.62). CONCLUSIONS: Serum 25(OH)D levels were low in 58.3 % of our BE cohort. There was no association between 25(OH)D levels and prevalence or incidence of HGD/EAC in patients with BE. Further long-term studies are needed to study the association between vitamin D status and progression of dysplasia in BE.

Evolving data on risk and current screening recommendations for colorectal cancer in cystic fibrosis: Pre- and posttransplant.

Advances in treatment for cystic fibrosis (CF), including cystic fibrosis transmembrane conductor regulator (CFTR) modulators, have ushered in an era where patients with CF have much longer life expectancies. This shift in life expectancy demands increased attention to diseases of aging in patients with CF. A notable complication of CF is early-onset colorectal cancer (CRC), which is especially prevalent in patients with severe mutations and after transplant. CFTR acts as a tumor suppressor gene based on knockout models. Lack of CFTR expression promotes carcinogenic processes such as intestinal inflammation and deleterious gut microbiome changes. The consensus Cystic Fibrosis Foundation recommendations advocate treating this population as a high-risk group, using a colonoscopy-only screening strategy starting at age 40 in patients without transplant and at age 30 after transplant. Screening should be considered every 5 years if negative and every 3 years or sooner for patients with adenomatous polyps. Future research will determine the role of noninvasive CRC screening tools in this population, as well as the effects of CFTR modulators on the risk of developing CRC.

Clovis organizational dynamics at a Late Glacial campsite in the central Great Lakes: Belson site excavations 2020-2021.

The Belson site is located on an outwash plain draining the Early Algonquin stage of the central Great Lakes (coinciding with the Older Dryas stadial period around 14,000 Cal B.P) southwest across Lower Michigan into the Ohio tributaries. By 13,000 Cal B.P the St. Joseph River had incised multiple channels into this plain. On a terrace just north of a now-abandoned channel, a detailed surface study by Talbot from 2005-2018 showed several flake clusters largely of Attica chert, procured about 235 km southwest of Belson. A study of the surface sample was published by the authors in 2021 and indicated that the points were made with the Clovis technological pattern. Excavations in 2020-21 revealed hundreds of buried flakes and multiple tools in the lower, less-disturbed terrace sediment. Plotting of this material indicates successive occupations below the ploughed deposit and covering more than 30 m2. The buried assemblages are similar to the published surface assemblage with the addition of more small scrapers and manufacturing debris. Several of the buried tools have traces of proteins from a range of mammals, suggesting a broad-spectrum subsistence strategy. The documentation of a succession of little disturbed deposits with precisely recorded micro-debris will allow for testing of models describing settlement choice and developing dynamics of internal site organization. Initial analysis of recovered data provides support for an 'outcrop centered' model where high-quality chert outcrops serve as central places on the landscape. Samples of sediment and charcoal for identification and dating await study.

Barrett's esophagus and the risk of obstructive sleep apnea: a case-control study.

BACKGROUND: Prior studies suggest that obstructive sleep apnea may be associated with gastroesophageal reflux disease, a strong risk factor for Barrett's esophagus. The goals of this pilot case-control study were to determine whether Barrett's esophagus patients have an increased likelihood of obstructive sleep apnea and to determine whether nocturnal gastroesophageal reflux symptoms affect the relationship between Barrett's esophagus and obstructive sleep apnea risk. METHODS: Patients with Barrett's esophagus completed the Berlin Questionnaire, a validated survey instrument identifying subjects at high risk for obstructive sleep apnea. Two outpatient control groups were recruited: 1) EGD Group, subjects matched to Barrett's esophagus cases by age, race, and gender with esophagogastroduodenoscopy negative for Barrett's esophagus; and 2) Colonoscopy Group, patients getting colonoscopy. Rates of scoring at high risk for obstructive sleep apnea were compared. Respondents were also questioned regarding severity of their typical gastroesophageal reflux symptoms and presence of nocturnal gastroesophageal reflux symptoms. RESULTS: The study included 287 patients (54 Barrett's esophagus, 62 EGD, and 171 colonoscopy subjects). Barrett's esophagus patients were slightly older than colonoscopy patients and more obese. 56% (n = 30) of Barrett's esophagus subjects scored at high risk for obstructive sleep apnea, compared with 42% (n = 26) of EGD subjects (OR 1.73, 95% CI [0.83, 3.62]) and 37% (n = 64) of colonoscopy patients (OR 2.08, 95% CI [1.12, 3.88]). The association between Barrett's esophagus and scoring at high risk for obstructive sleep apnea compared with colonoscopy patients disappeared after adjusting for age. Barrett's esophagus patients reported more severe typical heartburn and regurgitation symptoms than either control group. Among all subjects, patients with nocturnal reflux symptoms were more likely to score at high risk for obstructive sleep apnea than patients without nocturnal reflux. CONCLUSIONS: In this pilot study, a high proportion of Barrett's esophagus subjects scored at high risk for obstructive sleep apnea. Having Barrett's esophagus was associated with more severe gastroesophageal reflux symptoms, and nocturnal reflux symptoms were associated with scoring at high risk for obstructive sleep apnea. The need for obstructive sleep apnea screening in Barrett's esophagus patients with nocturnal gastroesophageal reflux symptoms should be further evaluated.

A comparison of epidural analgesia and traditional pain management effects on survival and cancer recurrence after colectomy: a population-based study.

BACKGROUND: Cancer recurrence after surgery may be affected by immunosuppressive factors such as surgical stress, anesthetic drugs, and opioids. By limiting exposure to these, epidural analgesia may enhance tumor surveillance. This study compared survival and cancer recurrence rates for resection of colorectal cancer between patients who received perioperative epidurals and those who did not. METHODS: The linked Medicare-Surveillance, Epidemiology, and End Results database was used to identify patients ages 66 yr or older with nonmetastatic colorectal cancer diagnosed between 1996 and 2005 who underwent open colectomy. Recurrence was defined as chemotherapy 16 months or more after surgery and/or radiation 12 months or more after surgery. Patients were followed for at least 4 yr. To account for hospital effects, overall survival was estimated via marginal Cox regression. Recurrence was estimated by conditional logistic regression. RESULTS: A cohort of 42,151 patients, of whom 22.9% (n = 9,670) had epidurals at the time of resection, was identified. 5-yr survival was 61% in the epidural group and 55% in the nonepidural group. There was a significant association between epidural use and improved survival (adjusted Cox model hazard ratio = 0.91, 95% CI = [0.87, 0.94]). Adjusting for covariates, there was no significant reduction of recurrence in the epidural group (odds ratio = 1.05, 95% CI = [0.95, 1.15]). Several covariates, including blood transfusion, were predictive of mortality and cancer recurrence. CONCLUSION: This large cohort study found that epidural use is associated with improved survival in patients with nonmetastatic colorectal cancer undergoing resection but does not support an association between epidural use and decreased cancer recurrence.

Laparoscopic versus open colectomy for colon cancer in an older population: a cohort study.

BACKGROUND: Laparoscopic colectomy for colon cancer has been compared with open colectomy in randomized controlled trials, but these studies may not be generalizable because of strict enrollment and exclusion criteria which may explicitly or inadvertently exclude older individuals due to associated comorbidities. Previous studies of older patients undergoing laparoscopic colectomy have generally focused on short-term outcomes. The goals of this cohort study were to identify predictors of laparoscopic colectomy in an older population in the United States and to compare short-term and long-term outcomes. METHODS: Patients aged 65 years or older with incident colorectal cancer diagnosed 1996-2002 who underwent colectomy within 6 months of cancer diagnosis were identified from the linked Surveillance, Epidemiology, and End Results-Medicare database. Laparoscopic and open colectomy patients were compared with respect to length of stay, blood transfusion requirements, intensive care unit monitoring, complications, 30-day mortality, and long-term survival. We adjusted for potential selection bias in surgical approach with propensity score matching. RESULTS: Laparoscopic colectomy cases were associated with left-sided tumors; areas with higher population density, income, and education level; areas in the western United States; and National Cancer Institute-designated cancer centers. Laparoscopic colectomy cases had shorter length of stay and less intensive care unit monitoring. Although laparoscopic colectomy patients (n = 424) had fewer complications (21.5% versus 26.3%), lower 30-day mortality (3.3% versus 5.8%), and longer median survival (6.6 versus 4.8 years) compared with open colectomy patients (n = 27,012), after propensity score matching these differences disappeared. CONCLUSIONS: In this older population, laparoscopic colectomy practice patterns were associated with factors which likely correlate with tertiary referral centers. Although short-term and long-term survival are comparable, laparoscopic colectomy offers shorter hospitalizations and less intensive care.

Coefficient of Fat Absorption to Measure the Efficacy of Pancreatic Enzyme Replacement Therapy in People With Cystic Fibrosis: Gold Standard or Coal Standard?

OBJECTIVES: We sought data on the validity, reliability, responsiveness, and feasibility of the coefficient of fat absorption (CFA) as a measure of pancreatic enzyme replacement therapy (PERT) efficacy in people with cystic fibrosis (pwCF) and reviewed the literature for alternative measures. METHODS: We searched PubMed for the Medical Subject Heading cystic fibrosis and the key words cystic fibrosis, fat absorption, CFA, and fecal fat imbalance; historical articles; and citations in bibliographies. RESULTS: The lower the CFA, the greater its variability; thus, it is less variable in healthy individuals who have higher CFA than pwCF. In addition, the test-retest values for CFA are more variable in pwCF than the general population. There is no correlation between CFA and body mass index or PERT dose but CFA is related to gastrointestinal signs and symptoms. Research-quality CFA studies are expensive, time consuming, and odious to pwCF and research staff. Sparse stool tests, breath tests, and blood tests of fat absorption have been studied as potential alternatives to CFA to measure PERT efficacy. CONCLUSIONS: Based on the evidence, we conclude that CFA as a measure of the efficacy of PERT is more of a "coal standard" than a gold standard; developing suitable alternatives should be a priority.

Mathematical model for determining the binding constants between immunoglobulins, bivalent ligands, and monovalent ligands.

This paper analyzes the equilibria between immunoglobulins (R(2)), homo-bifunctional ligands (L(2)), monovalent ligands (I), and their complexes. We present a mathematical model that can be used to estimate the concentration of each species present in a mixture of R(2), L(2), and I, given the initial conditions defining the total concentration of R(2), L(2), I, and four dissociation constants (K(d)(inter), K(d)(intra), K(d)(mono), and α). This model is based on fewer assumptions than previous models and can be used to describe exactly a broad range of experimental conditions. A series of curves illustrates the dependence of the equilibria upon the total concentrations of receptors and ligands, and the dissociation constants. We provide a set of guidelines for the design and analysis of experiments with a focus on estimating the binding constants from experimental binding isotherms. Two analytical equations relate the conditions for maximum aggregation in this system to the binding constants. This model is a tool to quantify the binding of immunoglobulins to antigens and a guide to understanding and predicting the experimental data of assays and techniques that employ immunoglobulins.

Editorial: Detection of small polyps: much ado about nothing?

Computed tomographic (CT) colonography (CTC) represents an alternative to optical colonoscopy for colorectal cancer screening. However, diminutive polyps (≤ 5 mm) are not routinely reported for CTC. An observational study comparing the rates of recovery of subcentimeter adenomas in average-risk patients between two screening strategies, CTC and optical colonoscopy, found that the colonoscopy group had a four and a half-fold greater recovery rate of diminutive adenomas. Although the study was not randomized, the results highlight the difference between the two screening strategies. Because of incomplete understanding of the natural history of diminutive adenomas, further study is needed to determine the long-term impact of the use of CTC for colorectal cancer screening.

Inactivation of CFTR by CRISPR/Cas9 alters transcriptional regulation of inflammatory pathways and other networks.

BACKGROUND: Individuals with cystic fibrosis (CF) experience elevated inflammation in multiple organs, but whether this reflects an inherent feature of CF cells or is a consequence of a pro-inflammatory environment is not clear. METHOD: Using CRISPR/Cas9-mediated mutagenesis of CFTR, 17 subclonal cell lines were generated from Caco-2 cells. Clonal lines with functional CFTR (CFTR+) were compared to those without (CFTR-) to directly address the role of CFTR in inflammatory gene regulation. RESULTS: All lines maintained CFTR mRNA production and formation of tight junctions. CFTR+ lines displayed short circuit currents in response to forskolin, while the CFTR- lines did not. Baseline expression of cytokines IL6 and CXCL8 (IL8) was not different between the lines regardless of CFTR genotype. All lines responded to TNFα and IL1ß by increasing IL6 and CXCL8 mRNA levels, but the CFTR- lines produced more CXCL8 mRNA than the CFTR+ lines. Transcriptomes of 6 CFTR- and 6 CFTR+ lines, before and after stimulation by TNFα, were compared for differential expression as a function of CFTR genotype. While some genes appeared to be differentially expressed simply because of CFTR's absence, others required stimulation for differences to be apparent. CONCLUSION: Together, these data suggest cells respond to CFTR's absence by modulating transcriptional networks, some of which are only apparent when cells are exposed to different environmental contexts, such as inflammation. With regards to inflammation, these data suggest a model in which CFTR's absence leads to a poised, pro-inflammatory state of cells that is only revealed by stimulation.

Sedation during endoscopy for patients at risk of obstructive sleep apnea.

BACKGROUND: Obstructive sleep apnea (OSA) has become increasingly prevalent in the United States and often goes undiagnosed. OBJECTIVE: To assess the proportion of patients undergoing routine endoscopic procedures who are at risk of OSA and to determine whether these patients are at risk of sedation-related hypoxia. DESIGN AND SETTING: Prospective case-control study at an academic medical center. PATIENTS AND INTERVENTIONS: Patients undergoing routine EGD and colonoscopy were administered the Berlin Questionnaire, a brief validated survey that stratifies patients into high or low risk of OSA. Data on pulse oximetry and oxygen use were collected. MAIN OUTCOME MEASUREMENTS: Rates of transient hypoxia, defined as a pulse oximetry measurement less than 92% requiring an increase in supplemental oxygen were compared between the high- and low-risk OSA groups. RESULTS: Of the 261 prospectively recruited patients, 28 were excluded for violating study protocol. Ninety (39%) of the remaining 233 patients were scored as being at high risk of OSA. There was no significant difference in the rate of transient hypoxia between the high- and low-risk groups (odds ratio 1.48; 95% CI, 0.58-3.80). LIMITATIONS: Single-center study. OSA was not confirmed with a sleep study. CONCLUSION: Approximately one third of patients undergoing routine outpatient endoscopic procedures at a university hospital scored as being at high risk of OSA. There was no significant difference in the rates of transient hypoxia between high- and low-risk groups, suggesting that the majority of patients with no diagnosis of OSA can undergo conscious sedation for routine endoscopic procedures with standard monitoring practices.

Mathematical modelling of fibre-enhanced perfusion inside a tissue-engineering bioreactor.

We develop a simple mathematical model for forced flow of culture medium through a porous scaffold in a tissue-engineering bioreactor. Porous-walled hollow fibres penetrate the scaffold and act as additional sources of culture medium. The model, based on Darcy's law, is used to examine the nutrient and shear-stress distributions throughout the scaffold. We consider several configurations of fibres and inlet and outlet pipes. Compared with a numerical solution of the full Navier-Stokes equations within the complex scaffold geometry, the modelling approach is cheap, and does not require knowledge of the detailed microstructure of the particular scaffold being used. The potential of this approach is demonstrated through quantification of the effect the additional flow from the fibres has on the nutrient and shear-stress distribution.

Surface, Interface, and Temperature Effects on the Phase Separation and Nanoparticle Self Assembly of Bi-Metallic Ni0.5Ag0.5: A Molecular Dynamics Study.

Classical molecular dynamics (MD) simulations were used to investigate how free surfaces, as well as supporting substrates, affect phase separation in a NiAg alloy. Bulk samples, droplets, and droplets deposited on a graphene substrate were investigated at temperatures that spanned regions of interest in the bulk NiAg phase diagram, i.e., miscible and immiscible liquid, liquid-crystal, and crystal-crystal regions. Using MD simulations to cool down a bulk sample from 3000 K to 800 K, it was found that phase separation below 2400 K takes place in agreement with the phase diagram. When free surface effects were introduced, phase separation was accompanied by a core-shell transformation: spherical droplets created from the bulk samples became core-shell nanoparticles with a shell made mostly of Ag atoms and a core made of Ni atoms. When such droplets were deposited on a graphene substrate, the phase separation was accompanied by Ni layering at the graphene interface and Ag at the vacuum interface. Thus, it should be possible to create NiAg core-shell and layer-like nanostructures by quenching liquid NiAg samples on tailored substrates. Furthermore, interesting bimetallic nanoparticle morphologies might be tuned via control of the surface and interface energies and chemical instabilities of the system.

Surgical approach and the impact of epidural analgesia on survival after esophagectomy for cancer: A population-based retrospective cohort study.

BACKGROUND: Esophagectomy for esophageal cancer carries high morbidity and mortality, particularly in older patients. Transthoracic esophagectomy allows formal lymphadenectomy, but leads to greater perioperative morbidity and pain than transhiatal esophagectomy. Epidural analgesia may attenuate the stress response and be less immunosuppressive than opioids, potentially affecting long-term outcomes. These potential benefits may be more pronounced for transthoracic esophagectomy due to its greater physiologic impact. We evaluated the impact of epidural analgesia on survival and recurrence after transthoracic versus transhiatal esophagectomy. METHODS: A retrospective cohort study was performed using the linked Surveillance, Epidemiology and End Results (SEER)-Medicare database. Patients aged ≥66 years with locoregional esophageal cancer diagnosed 1994-2009 who underwent esophagectomy were identified, with follow-up through December 31, 2013. Epidural receipt and surgical approach were identified from Medicare claims. Survival analyses adjusting for hospital esophagectomy volume, surgical approach, and epidural use were performed. A subgroup analysis restricted to esophageal adenocarcinoma patients was performed. RESULTS: Among 1,921 patients, 38% underwent transhiatal esophagectomy (n = 730) and 62% underwent transthoracic esophagectomy (n = 1,191). 61% (n = 1,169) received epidurals and 39% (n = 752) did not. Epidural analgesia was associated with transthoracic approach and higher volume hospitals. Patients with epidural analgesia had better 90-day survival. Five-year survival was higher with transhiatal esophagectomy (37.2%) than transthoracic esophagectomy (31.0%, p = 0.006). Among transthoracic esophagectomy patients, epidural analgesia was associated with improved 5-year survival (33.5% epidural versus 26.5% non-epidural, p = 0.012; hazard ratio 0.81, 95% confidence interval [0.70, 0.93]). Among the subgroup of esophageal adenocarcinoma patients undergoing transthoracic esophagectomy, epidural analgesia remained associated with improved 5-year survival (hazard ratio 0.81, 95% confidence interval [0.67, 0.96]); this survival benefit persisted in sensitivity analyses adjusting for propensity to receive an epidural. CONCLUSION: Among patients undergoing transthoracic esophagectomy, including a subgroup restricted to esophageal adenocarcinoma, epidural analgesia was associated with improved survival even after adjusting for other factors.