Roles for cerebellum and subsumption architecture in central pattern generation.

Within vertebrates, central pattern generators drive rhythmical behaviours, such as locomotion and ventilation. Their pattern generation is also influenced by sensory input and various forms of neuromodulation. These capabilities arose early in vertebrate evolution, preceding the evolution of the cerebellum in jawed vertebrates. This later evolution of the cerebellum is suggestive of subsumption architecture that adds functionality to a pre-existing network. From a central-pattern-generator perspective, what additional functionality might the cerebellum provide? The suggestion is that the adaptive filter capabilities of the cerebellum may be able to use error learning to appropriately repurpose pattern output. Examples may include head and eye stabilization during locomotion, song learning, and context-dependent alternation between learnt motor-control sequences.

Oxidative Cross Dehydrogenative Coupling of N-Heterocycles with Aldehydes through C(sp3)-H Functionalization.

Existing methodologies for metal-catalyzed cross-couplings typically rely on preinstallation of reactive functional groups on both reaction partners. In contrast, C-H functionalization approaches offer promise in simplification of the requisite substrates; however, challenges from low reactivity and similar reactivity of various C-H bonds introduce considerable complexity. Herein, the oxidative cross dehydrogenative coupling of α-amino C(sp3)-H bonds and aldehydes to produce ketone derivatives is described using an unusual reaction medium that incorporates the simultaneous use of di-tert-butyl peroxide as an oxidant and zinc metal as a reductant. The method proceeds with a broad substrate scope, representing an attractive approach for accessing α-amino ketones through the formal acylation of C-H bonds α to nitrogen in N-heterocycles. A combination of experimental investigation and computational modeling provides evidence for a mechanistic pathway involving cross-selective nickel-mediated cross-coupling of α-amino radicals and acyl radicals.

Comparison of auditory evoked potential thresholds in three shark species.

Auditory sensitivity measurements have been published for only 12 of the more than 1150 extant species of elasmobranchs (sharks, skates and rays). Thus, there is a need to further understand sound perception in more species from different ecological niches. In this study, the auditory evoked potential (AEP) technique was used to compare hearing abilities of the bottom-dwelling New Zealand carpet shark (Cephaloscyllium isabellum) and two benthopelagic houndsharks (Triakidae), the rig (Mustelus lenticulatus) and the school shark (Galeorhinus galeus). AEPs were measured in response to tone bursts (frequencies: 80, 100, 150, 200, 300, 450, 600, 800 and 1200 Hz) from an underwater speaker positioned 55 cm in front of the shark in an experimental tank. AEP detection thresholds were derived visually and statistically, with statistical measures slightly more sensitive (∼4 dB) than visual methodology. Hearing abilities differed between species, mainly with respect to bandwidth rather than sensitivity. Hearing was least developed in the benthic C. isabellum [upper limit: 300 Hz, highest sensitivity: 100 Hz (82.3±1.5 dB re. 1 µm s-2)] and had a wider range in the benthopelagic rig and school sharks [upper limit: 800 Hz; highest sensitivity: 100 Hz (79.2±1.6 dB re. 1 µm s-2) for G. galeus and 150 Hz (74.8±1.8 dB re. 1 µm s-2) for M. lenticulatus]. The data are consistent with those known for 'hearing non-specialist' teleost fishes that detect only particle motion, not pressure. Furthermore, our results provide evidence that benthopelagic sharks exploit higher frequencies (max. 800 Hz) than some of the bottom-dwelling sharks (max. 300 Hz). Further behavioural and morphological studies are needed to identify what ecological factors drive differences in upper frequency limits of hearing in elasmobranchs.

Comparison of acoustic particle acceleration detection capabilities in three shark species.

Behavioural studies have shown that sharks are capable of directional orientation to sound. However, only one previous experiment addresses the physiological mechanisms of directional hearing in sharks. Here, we used a directional shaker table in combination with the auditory evoked potential (AEP) technique to understand the broadscale directional hearing capabilities in the New Zealand carpet shark (Cephaloscyllium isabellum), rig shark (Mustelus lenticulatus) and school shark (Galeorhinus galeus). The aim of this experiment was to test if sharks are more sensitive to vertical (z-axis) or head-to-tail (x-axis) accelerations, and whether there are any differences between species. Our results support previous findings, suggesting that shark ears can receive sounds from all directions. Acceleration detection bandwidth was narrowest for the carpet shark (40-200 Hz), and broader for rig and school sharks (40-800 Hz). Greatest sensitivity bands were 40-80 Hz for the carpet shark, 100-200 Hz for the rig and 80-100 Hz for the school shark. Our results indicate that there may be differences in directional hearing abilities among sharks. The bottom-dwelling carpet shark was equally sensitive to vertical and head-to-tail particle accelerations. In contrast, both benthopelagic rig and school sharks appeared to be more sensitive to vertical accelerations at frequencies up to 200 Hz. This is the first study to provide physiological evidence that sharks may differ in their directional hearing and sound localisation abilities. Further comparative physiological and behavioural studies in more species with different lifestyles, habitats and feeding strategies are needed to further explore the drivers for increased sensitivity to vertical accelerations among elasmobranchs.

Fish bioacoustics: Navigating underwater sound.

Fish bioacoustics is about the sounds produced by fish, how fish hear, and what they hear. The focus of this article is on the hypothesis that some late pelagic stage reef fish larvae use the marine soundscape to locate reef settlement habitat. The hypothesis is evaluated by consideration of the nature of reef sound, hearing ability in late-stage larval fish, and direct behavioral evidence for orientation to reef sound.

Operant conditioning as a tool to assess hearing abilities in sharks.

Sharks (elasmobranchs) are an ancient, diverse group of fishes, representing a basal stage in the evolution of vertebrate hearing. Yet, our understanding of behavioural measures of hearing abilities in sharks is limited. To address this, an operant conditioning paradigm was designed, and scalloped hammerhead Sphyrna lewini and rig (spotted estuary smooth hound) Mustelus lenticulatus were successfully trained to respond to pure-tone acoustic stimuli from an underwater speaker. After 2-3 weeks of training, both species showed distinctive responses to these acoustic stimuli and retained this behaviour when reinforced. S. lewini responded to a 400 Hz pulsed tone with an abrupt increase in tailbeat frequency (97 beats per 30 s vs. 69 beats for a 2 kHz control and 70 beats for no signal) and sustained vigorous swimming (arousal response) for at least 30 s. In response to a 200 Hz pulsed tone, M. lenticulatus visited a target area under the speaker significantly more frequently (13.4 ± 4.3 times per minute vs. 1.4 ± 1.5 times for a 1.2 kHz control and 0.9 ± 0.01 times for no signal) and swam circles under the speaker to search for food. The authors used S. lewini arousal responses to pure-tone stimuli of 40, 80, 200, 400, 600 and 800 Hz to generate a provisional hearing-threshold curve. The results show that S. lewini adapts to low-frequency hearing (greatest sensitivity at 200 Hz, upper limit 800 Hz), which is like other coastal pelagic sharks that have been investigated so far. Despite challenges operant acoustic conditioning studies are a viable method for revealing auditory capabilities of sharks.

Machine learning based assessment of small-bodied fish tracking to evaluate spoiler baffle fish passage design.

Fish passage research is important to mitigate the adverse effects of fragmented river habitats caused by waterway structures. The scale at which this research is undertaken varies from small-scale laboratory prototype studies to in-situ observations at various fish passage structures and bottlenecks. Using DeepLabCut, we introduce and evaluate a machine learning based workflow to track small-bodied fish in order to facilitate improved fish passage management. We specifically studied the behaviour and kinematics of Galaxias maculatus, a widespread diadromous Southern Hemisphere fish species. Upstream fish passage was studied in the presence of three different patches of spoiler baffles at an average water velocity of 0.4 m/s. In semi-supervised mode, the fish locations were extracted, and fish behaviour, such as swimming pathways and resting locations, was analysed based on extracted positions and recorded kinematic parameters. Individual fish behaviour and kinematic parameters were then used to assess the suitability of the three different spoiler baffle designs for enhancing fish passage. Using this technique, we were able to demonstrate where different spoiler baffle configurations resulted in significant differences in fish passage success and behaviour. For example, medium-spaced smaller baffles provided more accessible and uniform resting locations, which were required for efficient upstream passage. Results are discussed in relation to fish passage management at small instream structures.

Graft Survival and Segment Discards Among Split-Liver and Reduced-Size Transplantations in the United States From 2008 to 2018.

Split-liver transplantation has allocation advantages over reduced-size transplantation because of its ability to benefit 2 recipients. However, prioritization of split-liver transplantation relies on the following 3 major assumptions that have never been tested in the United States: similar long-term transplant recipient outcomes, lower incidence of segment discard among split-liver procurements, and discard of segments among reduced-size procurements that would be otherwise "transplantable." We used United Network for Organ Sharing Standard Transplant Analysis and Research data to identify all split-liver (n = 1831) and reduced-size (n = 578) transplantation episodes in the United States between 2008 and 2018. Multivariable Cox proportional hazards modeling was used to compare 7-year all-cause graft loss between cohorts. Secondary analyses included etiology of 30-day all-cause graft loss events as well as the incidence and anatomy of discarded segments. We found no difference in 7-year all-cause graft loss (adjusted hazard ratio [aHR], 1.1; 95% confidence interval [CI], 0.8-1.5) or 30-day all-cause graft loss (aHR, 1.1; 95% CI, 0.7-1.8) between split-liver and reduced-size cohorts. Vascular thrombosis was the most common etiology of 30-day all-cause graft loss for both cohorts (56.4% versus 61.8% of 30-day graft losses; P = 0.85). Finally, reduced-size transplantation was associated with a significantly higher incidence of segment discard (50.0% versus 8.7%) that were overwhelmingly right-sided liver segments (93.6% versus 30.3%). Our results support the prioritization of split-liver over reduced-size transplantation whenever technically feasible.

Reliability of hospital-level mortality in abdominal aortic aneurysm repair.

OBJECTIVE: The relationship between volume and surgical outcomes has been shown for a variety of surgical procedures. The effects in abdominal aortic aneurysm repair have continued to be debated. Reliability adjustment has been used as a method to remove statistical noise from hospital-level outcomes. However, its impact on aortic aneurysm repair is not well understood. METHODS: We used prospectively collected data from the Vascular Quality Initiative to identify all patients who had undergone abdominal aortic aneurysm repair from 2003 to 2019. We first calculated the hospital-level risk-adjusted 30-day mortality rates. We subsequently used hierarchical logistic regression modeling to adjust for measurement reliability using empirical Bayes techniques. The effect of volume on risk- and reliability-adjusted mortality rates was then assessed using linear regression. RESULTS: Between 2003 and 2019, 67,073 abdominal aortic aneurysms were repaired, of which 11,601 (17.3%) were repaired with an open approach. The median annual volume was 7.4 (interquartile range, 3.0-13.3) for open repairs and 35.4 (interquartile range, 18.8-59.8) for endovascular repairs. Of the 223 hospitals that had performed open repairs during the study period, only 11 (4.9%) had performed ≥15 open repairs annually, and the risk-adjusted mortality rates varied from 0% to 75% across all centers. After reliability adjustment, the variability of the risk-adjusted mortality rates had decreased significantly to 1.3% to 8.2%. The endovascular repair risk-adjusted mortality rate variability had decreased from 0% to 14.3% to 0.3% to 2.8% after reliability adjustment. A decreasing trend in mortality was found with increasing an annual case volume for open repair with each additional annual case associated with a 0.012% decrease in mortality (P = .05); however, the relationship was not significant for endovascular repair (P = .793). CONCLUSIONS: We found that most hospitals do not perform a sufficient number of annual cases to generate a reliable center-specific mortality rate for open aneurysm repair. Center-specific mortality rates for low-volume centers should be viewed with caution, because a substantial proportion of the variation for these outcomes will be statistical noise rather than true center-level differences in the quality of care.

Glycosyl Exchange of Unactivated Glycosidic Bonds: Suppressing or Embracing Side Reactivity in Catalytic Glycosylations.

While developing boron-catalyzed glycosylations using glycosyl fluoride donors and trialkylsilyl ether acceptors, competing pathways involving productive glycosylation or glycosyl exchange were observed. Experimental and computational mechanistic studies suggest a novel mode of reactivity where a dioxolenium ion is a key intermediate that promotes both pathways through addition to either a silyl ether or to the acetal of an existing glycosidic linkage. Modifications in catalyst structure enable either pathway to be favored, and with this understanding, improved multicomponent iterative couplings and glycosyl exchange processes were demonstrated.

Video is better: why aren't we using it? A mixed-methods study of the barriers to routine procedural video recording and case review.

INTRODUCTION: Video-based case review for minimally invasive surgery is immensely valuable for education and quality improvement. Video review can improve technical performance, shorten the learning curve, disseminate new procedures, and improve learner satisfaction. Despite these advantages, it is underutilized in many institutions. So far, research has focused on the benefits of video, and there is relatively little information on barriers to routine utilization. METHODS: A 36-question survey was developed on video-based case review and distributed to the SAGES email list. The survey included closed and open-ended questions. Numeric responses and Likert scales were compared with t-test; open-ended responses were reviewed qualitatively through rapid thematic analysis to identify themes and sub-themes. RESULTS: 642 people responded to the survey for a response rate of 11%. 584 (91%) thought video would improve the quality of educational conferences. 435 qualitative responses on the value of video were analyzed, and benefits included (1) improved understanding, (2) increased objectivity, (3) better teaching, and (4) better audience engagement. Qualitative comments regarding specific barriers to recording and editing case video identified challenges at all stages of the process, from (1) the decision to record a case, (2) starting the recording in the OR, (3) transferring and storing files, and (4) editing the file. Each step had its own specific challenges. CONCLUSION: Minimally invasive surgeons want to increase their utilization of video-based case review, but there are multiple practical challenges to overcome. Understanding these barriers is essential in order to increase use of video for education and quality improvement.

Nickel-Catalyzed Decarboxylative Coupling of Redox-Active Esters with Aliphatic Aldehydes.

The addition of alkyl fragments to aliphatic aldehydes is a highly desirable transformation for fragment couplings, yet existing methods come with operational challenges related to the basicity and instability of the nucleophilic reagents commonly employed. We report herein that nickel catalysis using a readily available bioxazoline (BiOx) ligand can catalyze the reductive coupling of redox-active esters with aliphatic aldehydes using zinc metal as the reducing agent to deliver silyl-protected secondary alcohols. This protocol is operationally simple, proceeds under mild conditions, and tolerates a variety of functional groups. Initial mechanistic studies suggest a radical chain pathway. Additionally, alkyl tosylates and epoxides are suitable alkyl precursors to this transformation providing a versatile suite of catalytic reactions for the functionalization of aliphatic aldehydes.

Perioperative Risks of Sleeve Gastrectomy Versus Roux-en-Y Gastric Bypass Among Patients With Chronic Kidney Disease: A Review of the MBSAQIP Database.

OBJECTIVE: To determine whether patients with CKD experience higher rates of perioperative complications after RYGB compared to sleeve gastrectomy. SUMMARY OF BACKGROUND DATA: For obese CKD patients who qualify for bariatric surgery, sleeve gastrectomy is often preferred to RYGB based on perceptions of prohibitively-high perioperative risks surrounding RYGB. However, some patients with CKD are not candidates for sleeve gastrectomy and the incremental increased-risk from RYGB has never been rigorously tested in this population. METHODS: CKD patients who underwent RYGB or sleeve gastrectomy between 2015 and 2017 were identified from the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program Participant Use File. RYGB patients were 1:1 propensity-score matched with sleeve gastrectomy patients based on preoperative factors that influence operative choice. Primary outcomes included 30-day readmissions, surgical complications, medical complications, and death. Secondary outcomes included the individual complications used to create the composite surgical/medical complications. Univariate logistic regression was used to compare outcomes. E-value statistic was used to test the strength of outcome point estimates against possible unmeasured confounding. RESULTS: Demographics were similar between RYGB (n = 673) and sleeve gastrectomy (n = 673) cohorts. There were no statistically significant differences in primary outcomes. Among secondary outcomes, only acute kidney injury was statistically-significantly higher among RYGB patients (4.9% vs 2.7%, P = 0.035, E-value 1.27). CONCLUSIONS: Among well-matched cohorts of RYGB and sleeve gastrectomy patients, incidence of primary outcomes were similar. Among secondary outcomes, only acute kidney injury was statistically-significantly higher among RYGB patients; however, the E-value for this difference was small and relatively weak confounder(s) could abrogate the statistical difference. The perception that RYGB has prohibitively-high perioperative risks among CKD patients is disputable and operative selection should be weighed on patient candidacy and anticipated long-term benefit.

Fluoride Migration Catalysis Enables Simple, Stereoselective, and Iterative Glycosylation.

Challenges in the assembly of glycosidic bonds in oligosaccharides and glycoconjugates pose a bottleneck in enabling the remarkable promise of advances in the glycosciences. Here, we report a strategy that applies unique features of highly electrophilic boron catalysts, such as tris(pentafluorophenyl)borane, in addressing a number of the current limitations of methods in glycoside synthesis. This approach utilizes glycosyl fluoride donors and silyl ether acceptors while tolerating the Lewis basic environment found in carbohydrates. The method can be carried out at room temperature using air- and moisture-stable forms of the catalyst, with loadings as low as 0.5 mol %. These characteristics enable a wide array of glycosylation patterns to be accessed, including all C1-C2 stereochemical relationships in the glucose, mannose, and rhamnose series. This method allows one-pot, iterative glycosylations to generate oligosaccharides directly from monosaccharide building blocks. These advances enable the rapid and experimentally straightforward preparation of complex oligosaccharide units from simple building blocks.

Perioperative risks of bariatric surgery among patients with and without history of solid organ transplant.

Bariatric surgery is effective among patients with previous transplant in limited case series. However, the perioperative safety of bariatric surgery in this patient population is poorly understood. Therefore, we assessed the safety of bariatric surgery among previous-transplant patients using a database that captures >92% of all US bariatric procedures. All primary, laparoscopic sleeve gastrectomy and Roux-en-Y gastric bypass procedures between 2017 and 2018 were identified from the MBSAQIP dataset. Patients with previous transplant (n = 610) were compared with patients without previous transplant (n = 321 447). Primary outcomes were 30 day readmissions, surgical complications, medical complications, and death. Multivariable logistic regression with predictive margins was used to compare outcomes. Previous transplant patients experienced higher incidence of readmissions (8.0% vs 3.5%), surgical complications (5.0% vs 2.7%), and medical complications (4.3% vs 1.5%). There was no difference in incidence of death (0.2% vs 0.1%). Among individual complications, there no statistical differences in intraabdominal leak, unplanned reoperation, myocardial infarction, or infectious complications. Baseline estimated glomerular filtration rate was found to be a strong moderator of primary outcomes, with the highest risk of complications occurring at the lowest baseline estimated glomerular filtration rate. Given the many long-term benefits of bariatric surgery among patients with previous transplant, our findings should not preclude this patient population from operative consideration.

Rheotaxis revisited: a multi-behavioral and multisensory perspective on how fish orient to flow.

Here, we review fish rheotaxis (orientation to flow) with the goal of placing it within a larger behavioral and multisensory context. Rheotaxis is a flexible behavior that is used by fish in a variety of circumstances: to search for upstream sources of current-borne odors, to intercept invertebrate drift and, in general, to conserve energy while preventing downstream displacement. Sensory information available for rheotaxis includes water-motion cues to the lateral line and body-motion cues to visual, vestibular or tactile senses when fish are swept downstream. Although rheotaxis can be mediated by a single sense, each sense has its own limitations. For example, lateral line cues are limited by the spatial characteristics of flow, visual cues by water visibility, and vestibular and other body-motion cues by the ability of fish to withstand downstream displacement. The ability of multiple senses to compensate for any single-sense limitation enables rheotaxis to persist over a wide range of sensory and flow conditions. Here, we propose a mechanism of rheotaxis that can be activated in parallel by one or more senses; a major component of this mechanism is directional selectivity of central neurons to broad patterns of water and/or body motions. A review of central mechanisms for vertebrate orienting behaviors and optomotor reflexes reveals several motorsensory integration sites in the CNS that could be involved in rheotaxis. As such, rheotaxis provides an excellent opportunity for understanding the multisensory control of a simple vertebrate behavior and how a simple motor act is integrated with others to form complex behaviors.

Population-Based Analysis of Adherence to Postdischarge Extended Venous Thromboembolism Prophylaxis After Colorectal Resection.

BACKGROUND: Prevention of venous thromboembolism after colorectal surgery remains challenging. National guidelines endorse thromboembolism prophylaxis for 4 weeks after colorectal cancer resection. Expert consensus favors extended prophylaxis after IBD surgery. The actual frequency of prescription after resection remains unknown. OBJECTIVE: This study aimed to assess prescription of extended, postdischarge venous thromboembolism prophylaxis after resection in Michigan. DESIGN: This is a retrospective review of elective colorectal resections within a statewide collaborative receiving postdischarge, extended-duration prophylaxis. SETTING: This study was conducted between October 2015 and February 2018 at an academic center. PATIENTS: A total of 5722 patients (2171 with colorectal cancer, 266 with IBD, and 3285 with other). MAIN OUTCOME MEASURES: We compared the prescription of extended, postdischarge prophylaxis over time, between hospitals and by indication. RESULTS: Of 5722 patients, 373 (6.5%) received extended-duration prophylaxis after discharge. Use was similar between patients undergoing surgery for cancer (282/2171, 13.0%) or IBD (31/266, 11.7%, p = 0.54), but was significantly more common for both patients undergoing surgery for cancer or IBD in comparison with patients with other indications (60/3285, 1.8%, p < 0.001). Use increased significantly among patients with cancer (6.8%-16.8%, p < 0.001) and patients with IBD (0%-15.1%, p < 0.05) over the study period. For patients with other diagnoses, use was rare and did not vary significantly (1.5%-2.3%, p = 0.49). Academic centers and large hospitals (>300 beds) were significantly more likely to prescribe extended-duration prophylaxis for all conditions (both p < 0.001), with the majority of prophylaxis concentrated at only a few hospitals. LIMITATIONS: This study was limited by the lack of assessment of actual adherence, small number of observed venous thromboembolism events, small sample of patients with IBD, and restriction to the state of Michigan. CONCLUSIONS: The use of extended-duration venous thromboembolism prophylaxis after discharge is increasing, but remains uncommon in most hospitals. Efforts to improve adherence may require quality implementation initiatives or targeted payment incentives. See Video Abstract at http://links.lww.com/DCR/B193. ANÁLISIS POBLACIONAL DE LA ADHERENCIA A LA PROFILAXIS ANTI-TROMBÓTICA EXTENDIDA (TEV) EN PACIENTES DE ALTA LUEGO DE UNA RESECCIÓN COLORECTAL.: La prevención del tromboembolismo venoso después de cirugía colorrectal sigue siendo un desafío. Las guías nacionales han aprobado la profilaxia del tromboembolismo durante cuatro semanas luego de una resección de cáncer colorrectal. El consenso de expertos favorece la profilaxia extendida solamente después de la cirugía por enfermedad inflamatoria intestinal. La frecuencia real de prescripción después de la resección colorrectal sigue siendo desconocida.Evaluar la prescripción de profilaxia prolongada de tromboembolismo venoso después del alta luego de una resección colorrectal en Michigan.Revisión retrospectiva de las resecciones colorrectales electivas seguidas de una profilaxia de larga duración con el apoyo de todo el estado (MI).Este estudio se realizó entre octubre de 2015 y febrero de 2018 en un solo centro académico.Un universo de 5722 pacientes operados (2171 por cáncer colorrectal, 266 por enfermedad inflamatoria intestinal, 3285 por otros diagnósticos).Se comparó la prescripción de profilaxia prolongada después del alta según la duración, los hospitales y la indicación.De 5722 pacientes, 373 (6.5%) recibieron profilaxia de duración prolongada después del alta. El uso fue similar entre pacientes sometidos a cirugía por cáncer (282/2171, 13.0%) o enfermedad inflamatoria intestinal (31/266, 11.7%, p = 0.54), pero fue significativamente más común para ambos en comparación con pacientes con otras indicaciones (60/3285, 1.8%, p < 0.001). El uso aumentó significativamente entre pacientes con cáncer (6.8% a 16.8% (p < 0.001)) y en pacientes con enfermedad inflamatoria intestinal (0% a 15.1%, p < 0.05) durante el período de estudio. Para pacientes con otros diagnósticos, su utilización fue rara y no varió significativamente (1.5% a 2.3%, p = 0.49). Los centros académicos y los grandes hospitales (>300 camas) tenían mayor probabilidad de prescribir la profilaxia de duración extendida en todas las afecciones (ambas p < 0.001), pero la mayoría de las profilaxis se concentraron el algunos pocos grandes hospitales.Este estudio estuvo limitado por la falta de evaluación de actuales adherentes, por el pequeño número de eventos tromboembólicos venosos observados, por la pequeña muestra de pacientes con enfermedad inflamatoria intestinal y debido a ciertas restricciones en el estado de Michigan.El uso de profilaxia para el tromboembolismo venoso de duración prolongada después del alta está en aumento, pero su uso sigue siendo poco frecuente en la mayoría de los hospitales. Los esfuerzos para mejorar la adherencia al tratamiento pueden requerir iniciativas de mejoría en la calidad o incentivos específicos de reembolso. Consulte Video Resumen en http://links.lww.com/DCR/B193. (Traducción-Dr. Xavier Delgadillo).

Going the distance for procurement of donation after circulatory death livers for transplantation-Does reimbursement reflect reality?

Donation after circulatory death (DCD) liver transplantation (LT) has increased slowly over the past decade. Given that transplant surgeons generally determine liver offer acceptance, understanding surgeon incentives and disincentives is paramount. The purpose of this study was to assess aggregate travel distance per successful DCD versus deceased after brain death (DBD) liver procurement as a surrogate for surgeon time expenditure and opportunity cost. All consecutive liver offers made to Michigan Medicine from 2006 to 2017 were analyzed. Primary outcome was the summative travel distance (spent on all attempted procurements) per successful liver procurement that resulted in LT. Donation after circulatory death liver offer acceptance was lower than DBD liver offers, as was proportion of successful procurements among accepted offers. Overall, 10 275 miles were travelled for accepted DCD liver offers, resulting in 23 successful procurements (mean 447 miles per successful DCD liver procurement). For accepted DBD liver offers, 197 299 miles were travelled, resulting in 863 successful procurements (mean 229 miles per successful DBD liver procurement). On average, each successful DCD liver procurement required 218 more miles of travel than each successful DBD liver procurement. Current reimbursement policies poorly reflect increased surgeon travel (and time) expenditures between DCD and DBD liver offers.

Nickel-Catalyzed Three-Component Cycloadditions of Enoates, Alkynes, and Aldehydes.

A method for the three-component cycloaddition of enoates, alkynes, and aldehydes has been developed. Building upon previous work by this group in which stoichiometrically generated metallacycles undergo alkylation, we report a catalytic, alkylative [3 + 2] cycloaddition. From simple starting materials, structurally complex cyclopentenones may be rapidly assembled. Computational investigation of the mechanism (ωB97X-D3/cc-pVTZ//ωB97X/6-31G(d)) identified three energetically feasible pathways. Based on the relative rates of ketene formation compared to isomerization to a seven-membered metallacycle, the most likely mechanism has been determined to occur "ketene-first", with carbocyclization prior to aldol addition. Deuterium labeling studies suggest that formation of the seven-membered metallacycle becomes possible when an α-substituted enoate is used. This observed change in selectivity is due to the increased difficulty of phenoxide elimination with the inclusion of additional steric bulk of the α-substituent. The net transformation results in a [3 + 2] cycloaddition accompanied by an alkylation of the enoate substituent.

Bariatric surgery for prospective living kidney donors with obesity?

The obesity epidemic has gripped the transplant community. With nearly 40% of adults in the United States being obese (BMI ≥30 kg/m2 ) and 20% being morbidly obese (BMI ≥35 kg/m2 ), the implications for both donors and recipients of solid organs continue to grow.1 Nowhere is this more impactful than the candidacy of living kidney donors (LKDs). As increasing numbers of obese adults present for LKD consideration and evidence of inferior outcomes among obese LKDs grows, transplant surgeons will become progressively challenged by how to manage these patients in the clinic. Therefore, we offer this Personal Viewpoint to the transplant surgery community in order to review the current impact of obesity on living kidney donation, highlight what weight-loss interventions have already been attempted, and discuss the role that referral for weight-loss interventions including bariatric surgery might have going forward.