Genetic and telomeric variability: Insights from a tropical avian hybrid zone.

Telomere lengths and telomere dynamics can correlate with lifespan, behaviour and individual quality. Such relationships have spurred interest in understanding variation in telomere lengths and their dynamics within and between populations. Many studies have identified how environmental processes can influence telomere dynamics, but the role of genetic variation is much less well characterized. To provide a novel perspective on how telomeric variation relates to genetic variability, we longitudinally sampled individuals across a narrow hybrid zone (n = 127 samples), wherein two Manacus species characterized by contrasting genome-wide heterozygosity interbreed. We measured individual (n = 66) and population (n = 3) differences in genome-wide heterozygosity and, among hybrids, amount of genetic admixture using RADseq-generated SNPs. We tested for population differences in telomere lengths and telomere dynamics. We then examined how telomere lengths and telomere dynamics covaried with genome-wide heterozygosity within populations. Hybrid individuals exhibited longer telomeres, on average, than individuals sampled in the adjacent parental populations. No population differences in telomere dynamics were observed. Within the parental population characterized by relatively low heterozygosity, higher genome-wide heterozygosity was associated with shorter telomeres and higher rates of telomere shortening-a pattern that was less apparent in the other populations. All of these relationships were independent of sex, despite the contrasting life histories of male and female manakins. Our study highlights how population comparisons can reveal interrelationships between genetic variation and telomeres, and how naturally occurring hybridization and genome-wide heterozygosity can relate to telomere lengths and telomere dynamics.

Ongoing introgression of a secondary sexual plumage trait in a stable avian hybrid zone.

Hybrid zones are dynamic systems where natural selection, sexual selection, and other evolutionary forces can act on reshuffled combinations of distinct genomes. The movement of hybrid zones, individual traits, or both are of particular interest for understanding the interplay between selective processes. In a hybrid zone involving two lek-breeding birds, secondary sexual plumage traits of Manacus vitellinus, including bright yellow collar and olive belly color, have introgressed ~50 km asymmetrically across the genomic center of the zone into populations more genetically similar to Manacus candei. Males with yellow collars are preferred by females and are more aggressive than parental M. candei, suggesting that sexual selection was responsible for the introgression of male traits. We assessed the spatial and temporal dynamics of this hybrid zone using historical (1989-1994) and contemporary (2017-2020) transect samples to survey both morphological and genetic variation. Genome-wide single nucleotide polymorphism data and several male phenotypic traits show that the genomic center of the zone has remained spatially stable, whereas the olive belly color of male M. vitellinus has continued to introgress over this time period. Our data suggest that sexual selection can continue to shape phenotypes dynamically, independent of a stable genomic transition between species.

Cost-Reducing Traits for Agonistic Head Collisions: A Case for Neurophysiology.

Many animal species have evolved extreme behaviors requiring them to engage in repeated high-impact collisions. These behaviors include mating displays like headbutting in sheep and drumming in woodpeckers. To our knowledge, these taxa do not experience any notable acute head trauma, even though the deceleration forces would cause traumatic brain injury in most animals. Previous research has focused on skeletomuscular morphology, biomechanics, and material properties in an attempt to explain how animals moderate these high-impact forces. However, many of these behaviors are understudied, and most morphological or computational studies make assumptions about the behavior without accounting for the physiology of an organism. Studying neurophysiological and immune adaptations that covary with these behaviors can highlight unique or synergistic solutions to seemingly deleterious behavioral displays. Here, we argue that selection for repeated, high-impact head collisions may rely on a suite of coadaptations in intracranial physiology as a cost-reducing mechanism. We propose that there are three physiological systems that could mitigate the effects of repeated head trauma: (1) the innate neuroimmune response; (2) the glymphatic system, and (3) the choroid plexus. These systems are interconnected yet can evolve in an independent manner. We then briefly describe the function of these systems, their role in head trauma, and research that has examined how these systems may evolve to help reduce the cost of repeated, forceful head impacts. Ultimately, we note that little is known about cost-reducing intracranial mechanisms making it a novel field of comparative study that is ripe for exploration.

Right-sided Upper Extremity Access for Patients Undergoing Parallel Graft Placement during Endovascular Aortic Repair is Not Associated with Increased Neurologic Events When Compared with Left Upper Extremity Access.

BACKGROUND: The safety and efficacy of right axillary cannulation during complex aortic aneurysm repair for the deployment of chimney grafts is controversial; however, there are few studies that compare right and left upper extremity access. We favor the right axillary approach because of the relative ease of access to the visceral branches and the ability of surgeons and nursing staff to work on the same side of the patient, while avoiding the left sided image intensifier. We aim to demonstrate that right-sided access is equivalent or safer than left-sided access in terms of technical success and complication rates, with a focus on neurologic outcomes. METHODS: This is a single-institution retrospective study with a review of patients who underwent aortic intervention from January 2012 through December 2018. A total of 398 aortic interventions were performed, and 97 of these required brachial, axillary, or subclavian arterial access for attempted ChEVAR or thoracic endovascular aortic repair with parallel chimney grafts. Primary end points that were analyzed were site or sites of upper extremity access, technical success, 30-day mortality, cerebrovascular events, and subclavian/axillary artery injury. The number of parallel grafts, age, mean hospital length of stay, prior aortic intervention, emergent or elective status were also analyzed. RESULTS: Ninety-seven endovascular aortic operations required upper extremity access, with 67 using access from the right upper extremity, 26 using access from the left upper extremity, and 4 using bilateral upper extremity access. A total of 68.0% of patients had undergone prior aortic surgery. Technical success was achieved in 85 cases (87.6%). Five total patients suffered cerebrovascular accidents, with 2 occurring in left-sided access (7.7%), 2 in right-sided access (3.0%), and 1 in bilateral access (25%). CONCLUSIONS: Right upper extremity access for patients undergoing parallel graft placement during endovascular aortic aneurysm repair is a safe and feasible approach that is not associated with an increased risk of stroke or neurological events as compared with left upper extremity access.

Complete robotic repair of a renal artery aneurysm.

Although the majority of renal artery aneurysms require only observation, those that require treatment have been addressed primarily surgically or endovascularly. We report a case of surgical resection of a large, symptomatic renal artery aneurysm from an entirely robotic approach.

Functional outcome after resuscitative endovascular balloon occlusion of the aorta of the proximal and distal thoracic aorta in a swine model of controlled hemorrhage.

BACKGROUND: Noncompressible torso hemorrhage remains an ongoing problem for both military and civilian trauma. Resuscitative endovascular balloon occlusion of the aorta (REBOA) has been characterized as a potentially life-saving maneuver. The objective of this study was to determine the functional outcomes, paraplegia rates, and survival of 60-min balloon occlusion in the proximal and distal thoracic aorta in a porcine model of controlled hemorrhage. METHODS: Swine (Sus scrofa, 70-110 kg) were subjected to class IV hemorrhagic shock and underwent 60 min of REBOA. Devices were introduced from the left carotid artery and positioned in the thoracic aorta in either the proximal location (pREBOA [n = 8]; just past takeoff of left subclavian artery) or distal location (dREBOA [n = 8]; just above diaphragm). After REBOA, animals were resuscitated with whole blood, crystalloid, and vasopressors before a 4-day postoperative period. End points included evidence of spinal cord ischemia (clinical examination, Tarlov gait score, bowel and bladder dysfunction, and histopathology), gross ischemia-reperfusion injury (clinical examination and histopathology), and mortality. RESULTS: The overall mortality was similar between pREBOA and dREBOA groups at 37.5% (n = 3). Spinal cord-related mortality was 12.5% for both pREBOA and dREBOA groups. Spinal cord symptoms without death were present in 12.5% of pREBOA and dREBOA groups. Average gait scores improved throughout the postoperative period. CONCLUSIONS: REBOA placement in the proximal or distal thoracic aorta does not alter mortality or paraplegia rates as compared with controlled hemorrhage alone. Functional recovery improves in the presence or the absence of REBOA, although at a slower rate after REBOA as compared with negative controls. Additional research is required to determine the ideal placement of REBOA in an uncontrolled hemorrhage model to achieve use compatible with survival outcomes and quality of life.

When enough is enough: impact of packed red blood cells in massive transfusion outcomes.

Massive transfusion protocol (MTP) with fresh-frozen plasma and packed red blood cells (PRBCs) in a 1:1 ratio is one of the most common resuscitative strategies used in patients with severe hemorrhage. There are no studies to date that examine the best postoperative hematocrit range as a marker for survival after MTP. We hypothesize a postoperative hematocrit dose-dependent survival benefit in patients receiving MTP. This was a 53-month retrospective analysis of patients with intra-abdominal injuries requiring surgery and transfusion of 10 units PRBCs or more at a single Level I trauma center. Groups were defined by postoperative hematocrit (less than 21, 21 to 29, 29.1 to 39, and 39 or more). Kaplan-Meier (KM) survival probability was calculated. One hundred fifty patients requiring operative abdominal explorations and 10 units PRBCs or more were identified. There were no significant differences in demographics between groups. When comparing postoperative hematocrit groups, relative to a hematocrit of less than 21 per cent in KM survival analysis, an overall survival advantage was only evident in patients transfused to hematocrits 29.1 to 39 per cent (P < 0.03; odds ratio [OR], 0.284; 95% confidence interval [CI], 0.089 to 0.914). This survival advantage was not seen in the other groups (21 to 29: OR, 0.352; 95% CI, 0.103 to 1.195 or 39% or greater: OR, 0.107; 95% CI, 0.010 to 1.121). This is the first study to examine the impact of postoperative hematocrit as an indicator of survival after MTP in the trauma patient. Transfusion to hematocrits between 29.1 and 39 per cent conveyed a survival benefit, whereas resuscitation to supraphysiologic hematocrits 39 per cent or greater conveyed no additional survival benefit. This study highlights the need for judicious PRBC administration during MTP and its potential impact on survival in patients with postoperative supraphysiologic hematocrits.

The modern surgery department chairman: the job description as identified by chairmen.

IMPORTANCE: The role of the chairman of a surgery department is critical in academic surgery. However, little is known about the variability of job responsibilities. OBJECTIVE: To evaluate chairmen's responsibilities, methods of support, determinants of job performance success, and concerns. DESIGN: Internet-based survey. SETTING: Electronic survey system. PARTICIPANTS: Seventy-two chairmen. MAIN OUTCOMES AND MEASURES: Survey data on job responsibilities, methods of support, determinants of job performance success, and concerns. RESULTS: Of 168 chairmen who received the survey, 72 (43%) responded. The mean age of chairmen was 57 years (range, 44-78 years). Of 72 chairmen who responded, 69 (96%) were men, 67 (93%) were white, 65 (90%) were professors, 11 (15%) held a previous chair, 35 (49%) have advanced degrees, and 19 (26%) are program directors. Respondents are responsible for an average of 8.7 divisions, 60 (83%) spent 1 to 10 hours per week in the clinic, 45 (63%) performed surgery 1 to 10 hours per week, 54 (75%) took less than 6 call days per month, 44 (61%) published 1 to 6 papers per year and attended a mean (SD) of 4.3 (1.7) essential meetings per year, and 48 (67%) took 1 to 3 weeks of vacation annually. Chair salary support includes (from least to most) faculty tax, grants, endowment, school, and hospital. Compensation correlates with age, additional degree, specialty, location, contract, and tenure but not clinical hours. Reported compensation was consistent with data from the Association of American Medical Colleges, but 24 (33%) felt undercompensated. Incentives for job performance were given for clinical productivity (34 chairmen [47%]), department performance (50 [70%]), institutional performance (27 [38%]), and personal accomplishment (14 [19%]). Of 72 chairmen, 30 (42%) were concerned about personal liability related to the job, 15 (21%) had purchased personal liability insurance, and 20 (28%) have defended a lawsuit related to nonclinical responsibilities. CONCLUSIONS AND RELEVANCE: Academic surgery department chairmen have a wide array of responsibilities that have changed from historic standards. Success in the role of chairman may improve by appreciating the responsibilities, time allocation, methods of support, and concerns of other chairmen.