Cryptic carnivores: Intercontinental sampling reveals extensive novel diversity in a genus of freshwater annelids.

Freshwater annelids are globally widespread in aquatic ecosystems, but their diversity is severely underestimated. Obvious morphological features to define taxa are sparse, and molecular phylogenetic analyses regularly discover cryptic diversity within taxa. Despite considerable phylogenetic work on certain clades, many groups of freshwater annelids remain poorly understood. Included among these are water nymph worms of the genus Chaetogaster (Clitellata: Tubificida: Naididae: Naidinae). These worms have diverged from the detritivorous diet of most oligochaetes to become more predatory and exist as omnivores, generalist predators, parasites, or symbionts on other invertebrates. Despite their unusual trophic ecology, the true diversity of Chaetogaster and the phylogenetic relationships within the genus are uncertain. Only three species are commonly referenced in the literature (Chaetogaster diaphanus, Chaetogaster limnaei, and Chaetogaster diastrophus), but additional species have been described and prior molecular data suggests that there is cryptic diversity within named species. To clarify the phylogenetic diversity of Chaetogaster, we generated the first molecular phylogeny of the genus using mitochondrial and nuclear sequence data from 128 worms collected primarily across North America and Europe. Our phylogenetic analyses suggest that the three commonly referenced species are a complex of 24 mostly cryptic species. In our dataset, Chaetogaster "diaphanus" is represented by two species, C. "limnaei" is represented by three species, and C. "diastrophus" is represented by 19 species. North American and European sequences are largely interspersed across the phylogeny, with four pairs of clades involving distinct North American and European sister groupings. Overall, our study demonstrates that the species diversity of Chaetogaster has been underestimated and that carnivory has evolved at least twice in the genus. Chaetogaster is being used as a model for symbiotic evolution and the loss of regenerative ability, and our study indicates that researchers must be careful to identify which species of Chaetogaster they are working with in future studies.

Decreasing Colectomy Rates in Advanced Adenomas.

Advanced colon adenomas are commonly treated with colectomy, which is associated with substantial morbidity and mortality. Novel endoscopic resection techniques have been described, including endoscopic mucosal resection (EMR) and endoscopic submucosal resection (ESR), which demonstrate promise in treating these neoplasms without colectomy. We performed a retrospective review of patients with advanced adenomas who were referred to a colorectal surgeon for evaluation for resection over 4 years. 40 of 46 (87%) of these patients underwent a successful endoscopic resection. 10 of 46 (21.6%) patients ultimately underwent an operation for a variety of reasons: inability to resect endoscopically (n = 6), invasive cancer on the excised specimen (n = 2), complication of procedure (n = 1), colectomy after polyp recurrence (n = 1). Our study demonstrates EMR and ESD offers an alternative to colectomy in appropriately selected patients with a high success rate. As more surgeons learn advanced endoscopic techniques, there is potential to decrease colectomy rates in benign disease.

The Cost of Frailty in Complex Gastrointestinal Surgery.

BACKGROUND: Frailty is a syndrome characterized by decreased physiologic reserve related with aging; it has been associated with increased costs of health care. Factors driving its economic impact remain poorly understood. We examine the association between frailty, complications, and costs in complex gastrointestinal surgery. METHODS: Retrospective review of a prospective database encompassing elective complex gastrointestinal operations from 2017 to 2018 at a tertiary care hospital. Patients were categorized into non-frail (NF): MFI 0, pre-frail (PF): MFI 1-2, and frail (FR): MFI >2 based on the 5-Factor Modified Frailty Index. Linear regression models were applied. RESULTS: 612 patients were included; 268 (44%) were NF, 325 (53%) were PF, and 19 (3%) were FR. The FR group had a longer length of stay (7.26 days) compared to NF (5.05 days) or PF (5.67 days) (p = 0.031). The average total cost of care for all patients was $19,413.06 (CI 18,297.13-20,528.98). The cost for NF was $17,648.54 (CI 15,969.18-19,327.9), PF $20,435.70 (CI 18,911.01-21,960.4, p = .016), and FR patients was $26,809.36 (CI 20,511.9-33,106.81). A complication was observed in 91 patients (14.9%); of these, 76 (12.4%) were serious complications, as defined by NSQIP. There was no difference in incidence of complications (NF 14.93%, PF 14.46%, FR 21.05%, p = .734). On average, a complication added $12,656.67 regardless of frailty category. DISCUSSION: Frail patients are more costly and have a longer length of stay than their more robust counterparts. Complications were the major driver of costs after complex gastrointestinal surgery regardless of frailty status.

Robotic Repair of a Symptomatic Perineal Hernia With Self-Fixating Synthetic Mesh.

Primary acquired perineal hernias are rare defects through the pelvic floor diaphragm. The optimal surgical technique for repair remains unknown, and recurrence rates approach 50%. We present a 65-year-old female without previous obstetric or pelvic surgical history who was found to have herniated sigmoid colon through a 2×2 cm levator ani defect. The patient underwent robotic transabdominal hernia repair with a synthetic self-fixating underlay mesh. The peritoneum was primarily closed and the patient was discharged the same day. There is no sign of recurrence to date. Our minimally invasive approach with extraperitoneal mesh placement provided us with several advantages: ambulatory surgery; excellent visualization of the defect; easier suturing in the deep pelvis compared to traditional laparoscopy; and mesh reinforcement while minimizing the risks of erosion, migration, adhesion, and fistula formation.

The Effect of Resident Participation on Appendectomy Operative Times.

OBJECTIVE: To assess the association between level of resident autonomy and operative times for appendectomies. DESIGN: A single center retrospective analysis of electronic medical record data of patients who underwent an appendectomy from 1/1/2017 to 12/31/2018. Medical record numbers s were matched with cases entered in the ACGME Resident Case Log system. Cases were stratified by resident role ("First Assistant," "Surgeon Junior," "Surgeon Chief," or "Teaching Assistant") and operative times were compared to cases without resident participation using student's t test. SETTING: Maine Medical Center, Department of Surgery, Portland, Maine. PARTICIPANTS: Inclusion criteria: ≥5 years old, underwent appendectomy at a tertiary medical center during the study duration, and either had corresponding Case-log data or had no resident involvement. Patients who underwent appendectomy as part of a larger procedure were excluded. RESULTS: Six hundred eighty-eight patients met inclusion criteria, with residents participating in 574 (83.5%) cases. Overall mean operating time was 51 ± 21.5 minutes. Attending physicians without resident participation had the shortest OR times (43 ± 19.1 minutes). There was no difference in operating time between chief resident involvement and attending physicians without resident participation (45 ± 21; p = 0.43). Cases with residents involved as "First Assistant" (53 ± 18.6 minutes; p = 0.04) "Surgeon Junior" (52 ± 24.0 minutes; p < 0.001), or "Teaching Assistant" (57 ± 21.6 minutes; p < 0.001) were found to have longer operating times as compared to attending physicians operating without a resident. CONCLUSIONS: Operative times for appendectomies are impacted by resident role. Chief residents' operative times approach that of attendings when operating as Surgeon Chief, however they are significantly longer when operating as Teaching Assistant. Involvement of junior residents in any role lengthen operating times. This suggests that surgical education influences operating room efficiency.

Prey, populations, and the pleistocene: evidence for low COI variation in a widespread North American leech.

Placobdella rugosa has long presented challenges to leech biologists. Its extreme morphological variability and similarity to some congeneric species has confounded classification for over a century. Recent molecular analyses revealed a surprising lack of genetic variation among morphologically disparate, geographically widespread specimens of P. rugosa. Given the lack of any obvious mechanism by which this species could disperse between distant habitats, it was expected that widespread populations would be genetically isolated from each other. In the present study, we investigate the relationship between geographic distance and genetic diversity in P. rugosa using COI sequences from specimens collected across Canada and the United States. Although we find preliminary evidence for a barrier to gene flow between eastern and western collecting localities, our vastly expanded dataset largely corroborates prior studies, showing minimal phylogeographic signal among the sequences and negligible levels of genetic isolation by distance. A recent range expansion following the last ice age and/or host-mediated dispersal are discussed as potential explanations for this unexpected phylogeographic pattern.

Cherenkov radiation conversion and collection considerations for a gamma bang time/reaction history diagnostic for the NIF.

Bang time and reaction history measurements are fundamental components of diagnosing inertial confinement fusion (ICF) implosions and will be essential contributors to diagnosing attempts at ignition on the National Ignition Facility (NIF). Fusion gammas provide a direct measure of fusion interaction rate without being compromised by Doppler spreading. Gamma-based gas Cherenkov detectors that convert fusion gamma rays to optical Cherenkov photons for collection by fast recording systems have been developed and fielded at Omega. These systems have established their usefulness in illuminating ICF physics in several experimental campaigns. Bang time precision better than 25 ps has been demonstrated, well below the 50 ps accuracy requirement defined by the NIF system design requirements. A comprehensive, validated numerical study of candidate systems is providing essential information needed to make a down selection based on optimization of sensitivity, bandwidth, dynamic range, cost, and NIF logistics. This paper presents basic design considerations arising from the two-step conversion process from gamma rays to relativistic electrons to UV/visible Cherenkov radiation.