Adaptive evolution in ecological communities.

Understanding how natural selection drives evolution is a key challenge in evolutionary biology. Most studies of adaptation focus on how a single environmental factor, such as increased temperature, affects evolution within a single species. The biological relevance of these experiments is limited because nature is infinitely more complex. Most species are embedded within communities containing many species that interact with one another and the physical environment. To understand the evolutionary significance of such ecological complexity, experiments must test the evolutionary impact of interactions among multiple species during adaptation. Here we highlight an experiment that manipulates species composition and tracks evolutionary responses within each species, while testing for the mechanisms by which species interact and adapt to their environment. We also discuss limitations of previous studies of adaptive evolution and emphasize how an experimental evolution approach can circumvent such shortcomings. Understanding how community composition acts as a selective force will improve our ability to predict how species adapt to natural and human-induced environmental change.

Carotid stenting for symptomatic carotid artery web: Multicenter experience.

OBJECTIVE: Carotid artery webs are an underappreciated cause of recurrent ischemic stroke, and may represent a significant portion of cryptogenic stroke. Evidence-based guidelines for the management of symptomatic carotid webs do not exist. The goal of this study is to audit our local experience for patients with symptomatic carotid artery webs undergoing carotid stenting as a treatment option, along with describing the hypothesized dynamic physiology of carotid webs. METHODS: All patients undergoing stenting for symptomatic carotid artery web at two comprehensive regional stroke centers with high endovascular thrombectomy volume from January 1, 2012 to March 1, 2021 were included. The modified Rankin Scale (mRS) score was used to define functional outcome at 3 months after stenting. RESULTS: Fourteen consecutive patients with symptomatic carotid artery webs underwent stenting. Twelve patients were female (86%), with a median age of 54 (IQR, 48-64) years across all patients. Stroke was the qualifying event in 12 (86%) patients and TIA in 2. Eleven patients (11/14, 79%) achieved a mRS score of 0-2 at 90 days, 2 (14%) were mRS 3-5, and one patient was lost to follow-up. The median follow-up was 12 months (IQR, 10-12). There was no recurrent stroke or TIA like symptoms in any patients. CONCLUSIONS: Carotid stenting appears to be safe at preventing recurrent stroke/TIA with a median follow-up of 12 months in this retrospective multicenter observational study.

Impact of online transesophageal echocardiographic simulation on learning to navigate the 20 standard views.

OBJECTIVE: To overcome a challenge in transesophageal echocardiographic (TEE) training, an online virtual TEE simulation was developed that allows the user to navigate among the 20 standard views. The TEE probe position and ultrasound plane movements on a 3-dimensional heart model were displayed with the corresponding TEE video recording as the probe was moved among the views. DESIGN: This study evaluated the educational benefit of the virtual TEE application using a pretest/post-test design. SETTING: Single academic teaching hospital. PARTICIPANTS: Ten postgraduate physician volunteers who were novice echocardiographers. INTERVENTIONS: In a controlled environment, 10 study subjects completed a 20 multiple-choice question pretest, used the simulation for 1 hour, and then completed a 20 multiple-choice question post-test. Percentages of correct answers for each test were recorded for each subject. MEASUREMENTS AND MAIN RESULTS: The hypothesis that the median improvement in the number of questions correctly answered was different from 0 was tested with a related-samples Wilcoxon signed-rank test. A p value <0.05 was considered significant. A 1-hour exposure to the virtual TEE simulation produced a significant improvement (p = 0.005) in the post-test score (median 80%) compared with the pretest score (median 20%). CONCLUSIONS: Using the virtual TEE simulation for 1 hour significantly improves the trainees' knowledge of navigation among the 20 standard TEE views. This application freely is available on the Internet and will be a useful adjunct to TEE training programs.

MACULAR HOLE HYDRODISSECTION TECHNIQUE WITH HUMAN AMNIOTIC MEMBRANE FOR REPAIR OF LARGE MACULAR HOLES.

PURPOSE: To describe a combined surgical technique using the macular hole hydrodissection (MHH) with human amniotic membrane for repair of large macular holes. METHODS: A step-by-step procedure and a surgical video using the combined MHH and human amniotic membrane technique are presented. DESCRIPTION AND TECHNIQUE: As the first step, the MHH separates the adhesions of the macular hole to the underlying retinal pigment epithelium with a soft-tipped cannula through proportional reflux followed by gentle passive aspiration. The human amniotic membrane graft is marked to identify the nonsticky epithelial side and ensure that the stromal layer (sticky and nonshinny) is facing downward toward the retinal pigment epithelium. The graft is then tucked into the space created with MHH between the macular hole edges and the retinal pigment epithelium with closed forceps to decrease the likelihood of the graft from dislocating postoperatively. CONCLUSION: The MHH in combination with the human amniotic membrane is a practical and effective technique for addressing challenging large macular holes.

An interactive online 3D model of the heart assists in learning standard transesophageal echocardiography views.

PURPOSE: Transesophageal echocardiography (TEE) is becoming a standard imaging tool during cardiac surgery as well as an important diagnostic tool in cardiology and in intensive care, resulting in an increasing demand for TEE training. To address the problem of limited time for learning during TEE studies, we have developed a novel online application that allows users to visualize each of the 20 standard diagnostic TEE views in conjunction with a three-dimensional (3D) heart model that can be rotated and "cut away" above the echo plane to reveal the internal cardiac structures. This study is an evaluation of the educational benefit of this application. METHODS: The application was evaluated using a pre-test/post-test design assessing the improvement of subjects' test scores following three days of access to the application. The subjects were postgraduate fellows in anesthesia, cardiology, and cardiac surgery. RESULTS: Ten subjects showed a significant increase (31%) in their test scores after an average of 130 min of access to the application over a three-day period (P < 0.001, effect size = 1.9). Using five-point Likert scales, the users indicated that the application was a useful addition to their training (4.7), they would recommend the application to their colleagues (4.9), and they found the application easy to use (4.4). CONCLUSION: The large improvement in test scores during a short period of study and the high level of satisfaction across all of the disciplines indicates that the application is a useful adjunctive tool for learning TEE. It is now being used in TEE training worldwide.

An innovative pediatric chest tube insertion task trainer simulation: a technical report and pilot study.

INTRODUCTION: Iatrogenic complications associated with chest tube insertion (CTI) could be related to the gaps in the procedural fidelity of the current CTI training models and their insufficiency to support training of procedural mastery. A CTI bench model simulation developed with reference to preexisting curriculum increases trainees' exposure and practice of this clinical skill. Newly developed training models need to be recognized by trainees as a usable learning device. In this report, we describe the development of a novel CTI model, based on curriculum, and survey its usability as a training model among pediatric trainees. METHODS: Based on the acute trauma life support curriculum for CTI and expert interview, a pediatric CTI task trainer (PCTITT) model was developed, piloted, and then implemented for usability by volunteer pediatric residents and pediatric emergency fellows in 2 procedural training courses. Participants responded to 11 questions designed to capture self-reported attitudes toward the usability of the PCTITT as a training model for CTI. Results were obtained using a subjective 5-point Likert scale. RESULTS: Of the 32 participants, we achieved a response rate of 75%. Of these respondents, 92% had some kind of CTI hands-on training in the past, and 50% had experience with a real patient. Of these respondents, 91% recommended this model for training, and 80% stated that this model was superior to previous models. CONCLUSIONS: A PCTITT is an easy to create and feasible bench top task trainer to teach CTI skills, which integrates with other simulations currently in use the process of teaching CTI. Trainees recognized it as usable and superior to previous models. Future work needs to focus on the improvement of model fidelity, skills transferability, and tool validation.

Cerebrospinal fluid shunt insertion: techniques of peritoneal catheter placement separate from abdominal fascial and peritoneal incisions.

Good abdominal wall closure is one of the basic surgical skills and is a common feature of almost all modern-day CSF shunt operations. The fact that some patients require multiple abdominal operations highlights the need for a simple and effective technique for peritoneal catheter insertion through the abdominal wall and abdominal wall closure. Although technically simple, abdominal wall closure becomes more complex when combined with the requirement to maintain CSF shunt function in cases in which the shunt catheter passes through the abdominal wall into the peritoneal cavity. In this report, the authors describe a simple technique for passing the peritoneal catheter of a ventriculoperitoneal shunt through the abdominal wall on a pathway separate from the fascial opening. This technique minimizes the risk of abdominal wall-related complications and is especially important in high-risk patients such as those with obesity and/or diabetes and in children.