Reproductive isolation in a three-way contact zone.

Contact zones between divergent forms within a species provide insight into the role of gene flow in adaptation and speciation. Previous work has focused on contact zones involving only two divergent forms, but in nature, many more than two populations may overlap simultaneously and experience gene flow. Patterns of introgression in wild populations are, therefore, likely much more complicated than is often assumed. We begin to address this gap in current knowledge by investigating patterns of divergence and introgression across a complex natural contact zone. We use phenotypic and genomic data to confirm the existence of a three-way contact zone among divergent freshwater resident, saltwater resident and saltwater migratory three-spined stickleback (Gasterosteus aculeatus) on the island of North Uist, Scottish Western Isles. We find evidence for hybridization, mostly between saltwater resident and saltwater migratory forms. Despite hybridization, genomic analyses reveal pairwise islands of divergence between all forms that are maintained across the contact zone. Genomic cline analyses also provide evidence for selection and/or hybrid incompatibilities in divergent regions. Divergent genomic regions occur across multiple chromosomes and involve many known adaptive loci and several chromosomal inversions. We also identify distinct immune gene expression profiles between forms, but no evidence for transgressive expression in hybrids. Our results suggest that reproductive isolation is maintained in this three-way contact zone, despite some hybridization, and that reduced recombination in chromosomal inversions may play an important role in maintaining this isolation.

Drainage-structuring of ancestral variation and a common functional pathway shape limited genomic convergence in natural high- and low-predation guppies.

Studies of convergence in wild populations have been instrumental in understanding adaptation by providing strong evidence for natural selection. At the genetic level, we are beginning to appreciate that the re-use of the same genes in adaptation occurs through different mechanisms and can be constrained by underlying trait architectures and demographic characteristics of natural populations. Here, we explore these processes in naturally adapted high- (HP) and low-predation (LP) populations of the Trinidadian guppy, Poecilia reticulata. As a model for phenotypic change this system provided some of the earliest evidence of rapid and repeatable evolution in vertebrates; the genetic basis of which has yet to be studied at the whole-genome level. We collected whole-genome sequencing data from ten populations (176 individuals) representing five independent HP-LP river pairs across the three main drainages in Northern Trinidad. We evaluate population structure, uncovering several LP bottlenecks and variable between-river introgression that can lead to constraints on the sharing of adaptive variation between populations. Consequently, we found limited selection on common genes or loci across all drainages. Using a pathway type analysis, however, we find evidence of repeated selection on different genes involved in cadherin signaling. Finally, we found a large repeatedly selected haplotype on chromosome 20 in three rivers from the same drainage. Taken together, despite limited sharing of adaptive variation among rivers, we found evidence of convergent evolution associated with HP-LP environments in pathways across divergent drainages and at a previously unreported candidate haplotype within a drainage.

Implementation of Entrustable Professional Activities in General Surgery: Results of a National Pilot Study.

OBJECTIVE: The ongoing complexity of general surgery training has led to an increased focus on ensuring the competence of graduating residents. Entrustable professional activities (EPAs) are units of professional practice that provide an assessment framework to drive competency-based education. The American Board of Surgery convened a group from the American College of Surgeons, Accreditation Council for Graduate Medical Education (ACGME) Surgery Review Committee, and Association of Program Directors in Surgery to develop and implement EPAs in a pilot group of residency programs across the country. The objective of this pilot study was to determine the feasibility and utility of EPAs in general surgery resident training. METHODS: 5 EPAs were chosen based on the most common procedures reported in ACGME case logs and by practicing general surgeons (right lower quadrant pain, biliary disease, inguinal hernia), along with common activities covering additional ACGME milestones (performing a consult, care of a trauma patient). Levels of entrustment assigned (1 to 5) were observation only, direct supervision, indirect supervision, unsupervised, and teaching others. Participating in site recruitment and faculty development occurred from 2017 to 2018. EPA implementation at individual residency programs began on July 1, 2018, and was completed on June 30, 2020. Each site was assigned 2 EPAs to implement and collected EPA microassessments on residents for those EPAs. The site clinical competency committees (CCC) used these microassessments to make summative entrustment decisions. Data submitted to the independent deidentified data repository every 6 months included the number of microassessments collected per resident per EPA and CCC summative entrustment decisions. RESULTS: Twenty-eight sites were selected to participate in the program and represented geographic and size variability, community, and university-based programs. Over the course of the 2-year pilot programs reported on 14 to 180 residents. Overall, 6,272 formative microassessments were collected (range, 0 to 1144 per site). Each resident had between 0 and 184 microassessments. The mean number of microassessments per resident was 5.6 (SD = 13.4) with a median of 1 [interquartile range (IQR) = 6]. There were 1,763 summative entrustment ratings assigned to 497 unique residents. The average number of observations for entrustment was 3.24 (SD 3.61) with a median of 2 (IQR 3). In general, PGY1 residents were entrusted at the level of direct supervision and PGY5 residents were entrusted at unsupervised practice or teaching others. For each EPA other than the consult EPA, the degree of entrustment reported by the CCC increased by resident level. CONCLUSIONS: These data provide evidence that widespread implementation of EPAs across general surgery programs is possible, but variable. They provide meaningful data that graduating chief residents are entrusted by their faculty to perform without supervision for several common general surgical procedures and highlight areas to target for the successful widespread implementation of EPAs.

Species delimitation using genomic data to resolve taxonomic uncertainties in a speciation continuum of pelagic seabirds.

Speciation is a continuous and complex process shaped by the interaction of numerous evolutionary forces. Despite the continuous nature of the speciation process, the implementation of conservation policies relies on the delimitation of species and evolutionary significant units (ESUs). Puffinus shearwaters are globally distributed and threatened pelagic seabirds. Due to remarkable morphological status the group has been under intense taxonomic debate for the past three decades. Here, we use double digest Restriction-Site Associated DNA sequencing (ddRAD-Seq) to genotype species and subspecies of North Atlantic and Mediterranean Puffinus shearwaters across their entire geographical range. We assess the phylogenetic relationships and population structure among and within the group, evaluate species boundaries, and characterise the genomic landscape of divergence. We find that current taxonomies are not supported by genomic data and propose a more accurate taxonomy by integrating genomic information with other sources of evidence. Our results show that several taxon pairs are at different stages of a speciation continuum. Our study emphasises the potential of genomic data to resolve taxonomic uncertainties, which can help to focus management actions on relevant taxa, even if they do not necessarily coincide with the taxonomic rank of species.

On the genetic architecture of rapidly adapting and convergent life history traits in guppies.

The genetic basis of traits shapes and constrains how adaptation proceeds in nature; rapid adaptation can proceed using stores of polygenic standing genetic variation or hard selective sweeps, and increasing polygenicity fuels genetic redundancy, reducing gene re-use (genetic convergence). Guppy life history traits evolve rapidly and convergently among natural high- and low-predation environments in northern Trinidad. This system has been studied extensively at the phenotypic level, but little is known about the underlying genetic architecture. Here, we use four independent F2 QTL crosses to examine the genetic basis of seven (five female, two male) guppy life history phenotypes and discuss how these genetic architectures may facilitate or constrain rapid adaptation and convergence. We use RAD-sequencing data (16,539 SNPs) from 370 male and 267 female F2 individuals. We perform linkage mapping, estimates of genome-wide and per-chromosome heritability (multi-locus associations), and QTL mapping (single-locus associations). Our results are consistent with architectures of many loci of small-effect for male age and size at maturity and female interbrood period. Male trait associations are clustered on specific chromosomes, but female interbrood period exhibits a weak genome-wide signal suggesting a potentially highly polygenic component. Offspring weight and female size at maturity are also associated with a single significant QTL each. These results suggest rapid, repeatable phenotypic evolution of guppies may be facilitated by polygenic trait architectures, but subsequent genetic redundancy may limit gene re-use across populations, in agreement with an absence of strong signatures of genetic convergence from recent analyses of wild guppies.

Patterns and predictors of fatigue following living donor nephrectomy: Findings from the KDOC Study.

This study sought to identify the prevalence, pattern, and predictors of clinical fatigue in 193 living kidney donors (LKDs) and 20 healthy controls (HCs) assessed at predonation and 1, 6, 12, and 24 months postdonation. Relative to HCs, LKDs had significantly higher fatigue severity (P = .01), interference (P = .03), frequency (P = .002), and intensity (P = .01), and lower vitality (P < .001), at 1-month postdonation. Using published criteria, significantly more LKDs experienced clinical fatigue at 1 month postdonation, compared to HCs, on both the Fatigue Symptom Inventory (60% vs. 37%, P < .001) and SF-36 Vitality scale (67% vs. 16%, P < .001). No differences in fatigue scores or clinical prevalence were observed at other time points. Nearly half (47%) reported persistent clinical fatigue from 1 to 6 months postdonation. Multivariable analyses demonstrated that LKDs presenting for evaluation with a history of affective disorder and low vitality, those with clinical mood disturbance and anxiety about future kidney failure after donation, and those with less physical activity engagement were at highest risk for persistent clinical fatigue 6 months postdonation. Findings confirm inclusion of fatigue risk in existing OPTN informed consent requirements, have important clinical implications in the care of LKDs, and underscore the need for further scientific examination in this population.

Pain expectancy, prevalence, severity, and patterns following donor nephrectomy: Findings from the KDOC Study.

Postoperative pain is an outcome of importance to potential living kidney donors (LKDs). We prospectively characterized the prevalence, severity, and patterns of acute or chronic postoperative pain in 193 LKDs at six transplant programs. Three pain measurements were obtained from donors on postoperative Day (POD) 1, 3, 7, 14, 21, 28, 35, 41, 49, and 56. The median pain rating total was highest on POD1 and declined from each assessment to the next until reaching a median pain-free score of 0 on POD49. In generalized linear mixed-model analysis, the mean pain score decreased at each pain assessment compared to the POD3 assessment. Pre-donation history of mood disorder (adjusted ratio of means [95% confidence interval (CI)]: 1.40 [0.99, 1.98]), reporting "severe" on any POD1 pain descriptors (adjusted ratio of means [95% CI]: 1.47 [1.12, 1.93]) and open nephrectomy (adjusted ratio of means [95% CI]: 2.61 [1.03, 6.62]) were associated with higher pain scores across time. Of the 179 LKDs who completed the final pain assessment, 74 (41%) met criteria for chronic postsurgical pain (CPSP), that is, any donation-related pain on POD56. Study findings have potential implications for LKD education, surgical consent, postdonation care, and outcome measurements.

Prior exposure to long-day photoperiods alters immune responses and increases susceptibility to parasitic infection in stickleback.

Seasonal disease and parasitic infection are common across organisms, including humans, and there is increasing evidence for intrinsic seasonal variation in immune systems. Changes are orchestrated through organisms' physiological clocks using cues such as day length. Ample research in diverse taxa has demonstrated multiple immune responses are modulated by photoperiod, but to date, there have been few experimental demonstrations that photoperiod cues alter susceptibility to infection. We investigated the interactions among photoperiod history, immunity and susceptibility in laboratory-bred three-spined stickleback (a long-day breeding fish) and its external, directly reproducing monogenean parasite Gyrodactylus gasterostei. We demonstrate that previous exposure to long-day photoperiods (PLD) increases susceptibility to infection relative to previous exposure to short days (PSD), and modifies the response to infection for the mucin gene muc2 and Treg cytokine foxp3a in skin tissues in an intermediate 12 L : 12 D photoperiod experimental trial. Expression of skin muc2 is reduced in PLD fish, and negatively associated with parasite abundance. We also observe inflammatory gene expression variation associated with natural inter-population variation in resistance, but find that photoperiod modulation of susceptibility is consistent across host populations. Thus, photoperiod modulation of the response to infection is important for host susceptibility, highlighting new mechanisms affecting seasonality of host-parasite interactions.

Neuromorphic Liquid Marbles with Aqueous Carbon Nanotube Cores.

Neuromorphic computing devices attempt to emulate features of biological nervous systems through mimicking the properties of synapses toward implementing the emergent properties of their counterparts, such as learning. Inspired by recent advances in the utilization of liquid marbles (LMs, microliter quantities of fluid coated in hydrophobic powder) for the creation of unconventional computing devices, we describe the development of LMs with neuromorphic properties through the use of copper coatings and 1.0 mg mL-1 carbon nanotube (CNT)-containing fluid cores. Experimentation was performed through sandwiching the LMs between two cup-style electrodes and stimulating them with repeated dc pulses at 3.0 V. Our results demonstrate that "entrainment" of CNT-filled copper LMs via periodic pulses can cause their electrical resistance to rapidly switch between high to low resistance profiles upon inverting the polarity of stimulation: the reduction in resistance between high and low profiles was approximately 88% after two rounds of entrainment. This effect was found to be reversible through reversion to the original stimulus polarity and was strengthened by repeated experimentation, as evidenced by a mean reduction in time to switching onset of 43%. These effects were not replicated in nanotube solutions not bound inside LMs. Our electrical characterization also reveals that nanotube-filled LMs exhibit pinched loop hysteresis IV profiles consistent with the description of memristors. We conclude by discussing the applications of this technology to the development of unconventional computing devices and the study of emergent characteristics in biological neural tissue.

A genetics-based approach confirms immune associations with life history across multiple populations of an aquatic vertebrate (Gasterosteus aculeatus).

Understanding how wild immune variation covaries with other traits can reveal how costs and trade-offs shape immune evolution in the wild. Divergent life history strategies may increase or alleviate immune costs, helping shape immune variation in a consistent, testable way. Contrasting hypotheses suggest that shorter life histories may alleviate costs by offsetting them against increased mortality, or increase the effect of costs if immune responses are traded off against development or reproduction. We investigated the evolutionary relationship between life history and immune responses within an island radiation of three-spined stickleback, with discrete populations of varying life histories and parasitism. We sampled two short-lived, two long-lived and an anadromous population using qPCR to quantify current immune profile and RAD-seq data to study the distribution of immune variants within our assay genes and across the genome. Short-lived populations exhibited significantly increased expression of all assay genes, which was accompanied by a strong association with population-level variation in local alleles and divergence in a gene that may be involved in complement pathways. In addition, divergence around the eda gene in anadromous fish is likely associated with increased inflammation. A wider analysis of 15 populations across the island revealed that immune genes across the genome show evidence of having diverged alongside life history strategies. Parasitism and reproductive investment were also important sources of variation for expression, highlighting the caution required when assaying immune responses in the wild. These results provide strong, gene-based support for current hypotheses linking life history and immune variation across multiple populations of a vertebrate model.

Waist belt and central obesity cause partial hiatus hernia and short-segment acid reflux in asymptomatic volunteers.

OBJECTIVE: There is a high incidence of inflammation and metaplasia at the gastro-oesophageal junction (GOJ) in asymptomatic volunteers. Additionally, the majority of patients with GOJ adenocarcinomas have no history of reflux symptoms. We report the effects of waist belt and increased waist circumference (WC) on the physiology of the GOJ in asymptomatic volunteers. DESIGN: 12 subjects with normal and 12 with increased WC, matched for age and gender were examined fasted and following a meal and with waist belts on and off. A magnet was clipped to the squamo-columnar junction (SCJ). Combined assembly of magnet-locator probe, 12-channel pH catheter and 36-channel manometer was passed. RESULTS: The waist belt and increased WC were each associated with proximal displacement of SCJ within the diaphragmatic hiatus (relative to upper border of lower oesophageal sphincter (LOS), peak LOS pressure point and pressure inversion point, and PIP (all p<0.05). The magnitude of proximal migration of SCJ during transient LOS relaxations was reduced by 1.6-2.6 cm with belt on versus off (p=0.01) and in obese versus non-obese (p=0.04), consistent with its resting position being already proximally displaced. The waist belt, but not increased WC, was associated with increased LOS pressure (vs intragastric pressure) and movement of pH transition point closer to SCJ. At 5 cm above upper border LOS, the mean % time pH <4 was <4% in all studied groups. Acid exposure 0.5-1.5 cm above SCJ was increased, with versus without, belt (p=0.02) and was most marked in obese subjects with belt. CONCLUSIONS: Our findings indicate that in asymptomatic volunteers, waist belt and central obesity cause partial hiatus herniation and short-segment acid reflux. This provides a plausible explanation for the high incidence of inflammation and metaplasia and occurrence of neoplasia at the GOJ in subjects without a history of reflux symptoms.

Development and validation of a questionnaire to assess fear of kidney failure following living donation.

Living kidney donors (LKDs) may feel more anxious about kidney failure now that they have only one kidney and the security of a second kidney is gone. The aim of this cross-sectional study was to develop and empirically validate a self-report scale for assessing fear of kidney failure in former LKDs. Participants were 364 former LKDs within the past 10 years at five US transplant centers and 219 healthy nondonor controls recruited through Mechanical Turk who completed several questionnaires. Analyses revealed a unidimensional factor structure, excellent internal consistency (α = 0.88), and good convergent validity for the Fear of Kidney Failure questionnaire. Only 13% of former donors reported moderate to high fear of kidney failure. Nonwhite race (OR = 2.9, P = 0.01), genetic relationship with the recipient (OR = 2.46, P = 0.04), and low satisfaction with the donation experience (OR = 0.49, P = 0.002) were significant predictors of higher fear of kidney failure. We conclude that while mild anxiety about kidney failure is common, high anxiety about future renal failure among former LKDs is uncommon. The Fear of Kidney Failure questionnaire is reliable, valid, and easy to use in the clinical setting.

The WZA: A window-based method for characterizing genotype-environment associations.

Genotype-environment association (GEA) studies have the potential to identify the genetic basis of local adaptation in natural populations. Specifically, GEA approaches look for a correlation between allele frequencies and putatively selective features of the environment. Genetic markers with extreme evidence of correlation with the environment are presumed to be tagging the location of alleles that contribute to local adaptation. In this study, we propose a new method for GEA studies called the Weighted-Z Analysis (WZA) that combines information from closely linked sites into analysis windows in a way that was inspired by methods for calculating FST . Performing GEA methods in analysis windows has the advantage that it takes advantage of the increased linkage disequilibrium expected surrounding sites subject to local adaptation. We analyse simulations modelling local adaptation to heterogeneous environments to compare the WZA with existing methods. In the majority of cases we tested, the WZA either outperformed single-SNP (single nucleotide polymorphism)-based approaches or performed similarly. In particular, the WZA outperformed individual SNP approaches when a small number of individuals or demes were sampled. Particularly troubling, we found that some GEA methods exhibit very high false positive rates. We applied the WZA to previously published data from lodgepole pine and identified candidate loci that were identified in the original study alongside numerous loci that were not found in the original study.

Measuring movement and location of the gastroesophageal junction: research and clinical implications.

Understanding the physiology of gastroesophageal junction (GEJ) is important as failure of its function is associated with reflux disease, hiatus hernia, and cancer. In recent years, there have been impressive developments in high resolution technologies allowing measurement of luminal pressure, pH, and impedance. One obvious deficiency is the lack of technique to monitor the movement and location of the GEJ over a prolonged period of time. Proximal movement of the GEJ during peristalsis and transient lower esophageal sphincter relaxations (TLESRs) is due to shortening of the longitudinal muscle of the esophagus. Techniques for measuring shortening include fluoroscopic imaging of mucosal clip, high-frequency intraluminal ultrasound, and high resolution manometry, but these techniques have limitations. Short segment reflux is recently found to be more common than traditional reflux and may account for the high prevalence of intestinal metaplasia and cancer seen at GEJ. While high resolution pHmetry is available, there is no technique that can reliably and continuously measure the position of the squamocolumnar junction. A new technique is recently reported allowing a precise and continuous measurement of the GEJ based on the principle of Hall effect. Reported studies have validated its accuracy both on the bench and against the gold standard, fluoroscopy. It has been used alongside high resolution manometry in studying the behavior of the GEJ during TLESRs and swallows. While there are challenges associated with this new technique, there are promising ongoing developments. There is exciting time ahead in research and clinical applications for this new technique.

Educational Value of Surgical Residents Operating as Teaching Assistant.

OBJECTIVE: To assess the educational of value of teaching assistant (TA) cases from the perspectives of attending, chief resident, and junior resident. We hypothesized the greatest educational value of TA cases would be for chief residents more so than other team members. DESIGN: A prospective survey was designed and collected for TA cases separately from attendings, chief residents, and junior residents to assess operative details and educational value. The study period ran from August 2021 through December 2022. Qualitative and quantitative analysis was undertaken to compare answers and discover themes in the free-text responses of attendings and residents. SETTING: Single center, tertiary care institution, Maine Medical Center, Department of Surgery, Portland, ME PARTICIPANTS: Sixty-nine teaching assistant cases were captured from a total of 117 completed surveys that were completed by 44 chief residents, 49 junior residents, 22 attendings (n = 22) and 2 APPs. RESULTS: A wide variety of TA cases were included in the study with the most common reason for performing a TA case being resident request 68%. Operative complexity was most commonly rated easiest third (50%) and middle third (41%) of overall cases. Both junior and chief residents felt that compared to working with an attending alone, TA cases contributed more or much more to their procedural independence >80% of the time. Attendings reported learning something about the resident's skills that they were not expecting in 59% of the cases. Thematic analysis: attendings focused on the steps of the procedure, including the technical aspects, particularly regarding opening while residents largely focused on communication and preparation. CONCLUSIONS: Teaching assistant cases seem to have more educational value for chief and junior residents than attendings. Both junior and chief residents felt that compared to working with an attending alone, TA cases contributed more or much more to their procedural independence >80% of the time.

Ring Attractors as the Basis of a Biomimetic Navigation System.

The ability to navigate effectively in a rich and complex world is crucial for the survival of all animals. Specialist neural structures have evolved that are implicated in facilitating this ability, one such structure being the ring attractor network. In this study, we model a trio of Spiking Neural Network (SNN) ring attractors as part of a bio-inspired navigation system to maintain an internal estimate of planar translation of an artificial agent. This estimate is dynamically calibrated using a memory recall system of landmark-free allotheic multisensory experiences. We demonstrate that the SNN-based ring attractor system can accurately model motion through 2D space by integrating ideothetic velocity information and use recalled allothetic experiences as a positive corrective mechanism. This SNN based navigation system has potential for use in mobile robotics applications where power supply is limited and external sensory information is intermittent or unreliable.

SNP discovery and genetic structure in blue mussel species using low coverage sequencing and a medium density 60 K SNP-array.

Blue mussels from the genus Mytilus are an abundant component of the benthic community, found in the high latitude habitats. These foundation species are relevant to the aquaculture industry, with over 2 million tonnes produced globally each year. Mussels withstand a wide range of environmental conditions and species from the Mytilus edulis complex readily hybridize in regions where their distributions overlap. Significant effort has been made to investigate the consequences of environmental stress on mussel physiology, reproductive isolation, and local adaptation. Yet our understanding on the genomic mechanisms underlying such processes remains limited. In this study, we developed a multi species medium-density 60 K SNP-array including four species of the Mytilus genus. SNPs included in the platform were called from 138 mussels from 23 globally distributed mussel populations, sequenced using a whole-genome low coverage approach. The array contains polymorphic SNPs which capture the genetic diversity present in mussel populations thriving across a gradient of environmental conditions (~59 K SNPs) and a set of published and validated SNPs informative for species identification and for diagnosis of transmissible cancer (610 SNPs). The array will allow the consistent genotyping of individuals, facilitating the investigation of ecological and evolutionary processes in these taxa. The applications of this array extend to shellfish aquaculture, contributing to the optimization of this industry via genomic selection of blue mussels, parentage assignment, inbreeding assessment and traceability. Further applications such as genome wide association studies (GWAS) for key production traits and those related to environmental resilience are especially relevant to safeguard aquaculture production under climate change.

Update on the Financial Well-Being of Surgical Residents in New England.

BACKGROUND: Poor personal financial health has been linked to key components of health including burnout, substance abuse, and worsening personal relationships. Understanding the state of resident financial health is key to improving their overall well-being. STUDY DESIGN: A secondary analysis of a survey of New England general surgery residents was performed to understand their financial well-being. Questions from the National Financial Capability Study were used to compare to an age-matched and regionally matched cohort. RESULTS: Overall, 44% (250 of 570) of surveyed residents responded. Residents more frequently reported spending less than their income each year compared to the control cohort (54% vs 34%, p < 0.01). However, 17% (39 of 234) of residents reported spending more than their income each year. A total of 65% of residents (152 of 234), found it "not at all difficult" to pay monthly bills vs 17% (76 of 445) of the control cohort (p < 0.01). However, 32% (75 of 234) of residents reported it was "somewhat" or "very" difficult to pay monthly bills. Residents more frequently reported they "certainly" or "probably" could "come up with" $2,000 in a month compared to the control cohort (85% vs 62% p < 0.01), but 16% (37 of 234) of residents reported they could not. In this survey, 21% (50 of 234) of residents reported having a personal life insurance policy, 25% (59 of 234) had disability insurance, 6% (15 of 234) had a will, and 27% (63 of 234) had >$300,000 worth of student loans. CONCLUSIONS: Surgical residents have better financial well-being than an age-matched and regionally matched cohort, but there is still a large proportion who suffer from financial difficulties.

Effect of dipyridamole plus aspirin on hemodialysis graft patency.

BACKGROUND: Arteriovenous graft stenosis leading to thrombosis is a major cause of complications in patients undergoing hemodialysis. Procedural interventions may restore patency but are costly. Although there is no proven pharmacologic therapy, dipyridamole may be promising because of its known vascular antiproliferative activity. METHODS: We conducted a randomized, double-blind, placebo-controlled trial of extended-release dipyridamole, at a dose of 200 mg, and aspirin, at a dose of 25 mg, given twice daily after the placement of a new arteriovenous graft until the primary outcome, loss of primary unassisted patency (i.e., patency without thrombosis or requirement for intervention), was reached. Secondary outcomes were cumulative graft failure and death. Primary and secondary outcomes were analyzed with the use of a Cox proportional-hazards regression with adjustment for prespecified covariates. RESULTS: At 13 centers in the United States, 649 patients were randomly assigned to receive dipyridamole plus aspirin (321 patients) or placebo (328 patients) over a period of 4.5 years, with 6 additional months of follow-up. The incidence of primary unassisted patency at 1 year was 23% (95% confidence interval [CI], 18 to 28) in the placebo group and 28% (95% CI, 23 to 34) in the dipyridamole-aspirin group, an absolute difference of 5 percentage points. Treatment with dipyridamole plus aspirin significantly prolonged the duration of primary unassisted patency (hazard ratio, 0.82; 95% CI, 0.68 to 0.98; P=0.03) and inhibited stenosis. The incidences of cumulative graft failure, death, the composite of graft failure or death, and serious adverse events (including bleeding) did not differ significantly between study groups. CONCLUSIONS: Treatment with dipyridamole plus aspirin had a significant but modest effect in reducing the risk of stenosis and improving the duration of primary unassisted patency of newly created grafts. (ClinicalTrials.gov number, NCT00067119.)