An Optimal Orthotopic Mouse Model for Human Colorectal Cancer Primary Tumor Growth and Spontaneous Metastasis.

BACKGROUND: Colorectal cancer is a leading cause of cancer-related death. Small animal models allow for the study of different metastatic patterns, but an optimal model for metastatic colorectal cancer has not been established. OBJECTIVE: The purpose of this study was to determine which orthotopic model most accurately emulates the patterns of primary tumor growth and spontaneous liver and lung metastases seen in patients with colorectal cancer. DESIGN: Using luciferase-tagged HT-29 cells coinoculated with lymph node stromal analog HK cells, 3 tumor cell delivery models were compared: intrarectal injection, intracecal injection, and acid enema followed by cancer cell instillation. Tumor growth was monitored weekly by bioluminescent imaging, and mice were sacrificed based on primary tumor size or signs of systemic decline. Liver and lungs were evaluated for metastases via bioluminescent imaging and histology. SETTINGS: The study was conducted at a single university center. MAIN OUTCOME MEASURES: Primary tumor and metastasis bioluminescent imaging were measured. RESULTS: Intrarectal injection had the lowest mortality at 4.0% (1/25) compared with the intracecal group at 17.4% (4/23) and the acid enema followed by cancer cell instillation group at 15.0% (3/20).The primary tumors in intrarectal mice had the highest average bioluminescence (3.78 × 10 ± 4.94 × 10 photons) compared with the mice in the intracecal (9.52 × 10 ± 1.92 × 10 photons; p = 0.012) and acid enema followed by cancer cell instillation groups (6.23 × 10 ± 1.23 × 10 photons; p = 0.0016). A total of 100% of intrarectal and intracecal mice but only 35% of mice in the acid enema followed by cancer cell instillation group had positive bioluminescent imaging before necropsy. Sixty percent of intrarectal mice had liver metastases, and 56% had lung metastases. In the intracecal group, 39% of mice had liver metastases, and 35% had lung metastases. Only 2 acid enema followed by cancer cell instillation mice developed metastases. LIMITATIONS: Tumor injections were performed by multiple investigators. Distant metastases were confirmed, but local lymph node status was not evaluated. CONCLUSIONS: Intrarectal injection is the safest, most reproducible, and successful orthotopic mouse model for human colorectal cancer primary tumor growth and spontaneous metastasis.

Comparison of 30-Day Postoperative Outcomes after Laparoscopic vs Robotic Colectomy.

BACKGROUND: The robotic platform has been used increasingly to perform colorectal surgery. The benefits of robotic colectomy when compared with laparoscopic colectomy have not been definitively established. STUDY DESIGN: A retrospective review of the NSQIP database was performed on patients undergoing elective laparoscopic or robotic colectomy in 2013. Demographic characteristics, length of stay, operative time, and 30-day postoperative complications were compared between the 2 groups. RESULTS: Of the 17,774 colectomies performed during the study period, 11,267 (63.4%) were performed laparoscopically and 653 (3.7%) were performed robotically. In comparison with laparoscopic colectomy, robotic colectomy was associated with increased operative time (233 vs 180 minutes; p < 0.01) and decreased length of stay (5.04 vs 6.06 days; p < 0.01). There was no significant difference with respect to mortality (0.2% vs 0.4%; p < 0.312), anastomotic leak (3.4% vs 3.1%; p = 0.715), reoperation (4.9% vs 4.0%; p = 0.27), conversion (10.3% vs 12.2%; p = 0.13), or readmission (9.3% vs 8.7%; p = 0.593) rates. The differences in length of stay and operative time persisted in the right colectomy and left colectomy/sigmoid resection subgroup analysis with no difference in conversion rates. CONCLUSIONS: In this head-to-head comparison of laparoscopic colectomy and robotic colectomy, the majority of postoperative outcomes were equivalent, except for an increase in operative time and shorter length of stay in the robotic group. Robotic colectomy appears to be a safe option for minimally invasive colectomy, but additional studies are needed to elucidate whether it is cost-effective when compared with laparoscopic colectomy.

Current State of Colorectal Surgery Training: A Survey of Program Directors, Current and Recently Matched Colorectal Residents, and Recent Colorectal Graduates.

BACKGROUND: Colorectal residency has become one of the more competitive postgraduate training opportunities; however, little information is available to guide potential applicants in gauging their competitiveness. OBJECTIVE: The aim of this study was to identify the current trends colorectal residency training and to identify what factors are considered most important in ranking a candidate highly. We hypothesized that there was a difference in what program directors, current and recently matched colorectal residents, and recent graduates consider most important in making a candidate competitive for a colorectal residency position. DESIGN: Three 10-question anonymous surveys were sent to 59 program directors, 87 current and recently matched colorectal residents, and 119 recent graduates in March 2015. SETTINGS: The study was conducted as an anonymous internet survey. MAIN OUTCOME MEASURES: Current trends in applying for a colorectal residency, competitiveness of recent colorectal residents, factors considered most important in ranking a candidate highly, and what future colorectal surgeons can expect after finishing their training were measured. RESULTS: The study had an overall response rate of 43%, with 28 (47%) of 59 program directors, 46 (53%) of 87 current and recently matched colorectal residents, and 39 (33%) of 119 recent graduates responding. The majority of program directors felt that a candidate's performance during the interview process was the most important factor in making a candidate competitive, followed by contact from a colleague, letters of recommendation, American Board of Surgery In-Training Exam scores, and number of publications/presentations. The majority of current and recently matched colorectal residents felt that a recommendation/telephone call from a colleague was the most important factor, whereas the majority of recent graduates favored letters of recommendation as the most important factor in ranking a candidate highly. LIMITATIONS: Limitations to the study include its small sample size, selection bias, responder bias, and misclassification bias. CONCLUSIONS: There are differences in what program directors and current/recent residents consider most important in making an applicant competitive for colorectal residency.

Is DNA barcoding actually cheaper and faster than traditional morphological methods: results from a survey of freshwater bioassessment efforts in the United States?

Taxonomic identification accounts for a substantial portion of cost associated with bioassessment programs across the United States. New analytical approaches, such as DNA barcoding have been promoted as a way to reduce monitoring costs and improve efficiency, yet this assumption has not been thoroughly evaluated. We address this question by comparing costs for traditional morphology-based bioassessment, the standard Sanger sequencing-based DNA barcoding approach, and emerging next-generation (NGS) molecular methods. Market demand for molecular approaches is also assessed through a survey of the level of freshwater bioassessment effort in the United States across multiple habitat types (lakes, streams, wetlands) and indicators (benthic invertebrates, fish, algae). All state and regional level programs administered by public agencies and reported via agency web sites were included in the survey. Costs were based on surveys of labs and programs willing to provide such information. More than 19,500 sites are sampled annually across the United States, with the majority of effort occurring in streams. Benthic invertebrates are the most commonly used indicator, but algae and fish comprise between 35% and 21% of total sampling effort, respectively. We estimate that between $104 and $193 million is spent annually on routine freshwater bioassessment in the United States. Approximately 30% of the bioassessment costs are comprised of the cost to conduct traditional morphology-based taxonomy. Current barcoding costs using Sanger sequencing are between 1.7 and 3.4 times as expensive as traditional taxonomic approaches, excluding the cost of field sampling (which is common to both approaches). However, the cost of NGS methods are comparable (or slightly less expensive) than traditional methods depending on the indicator. The promise of barcoding as a cheaper alternative to current practices is not yet realized, although molecular methods may provide other benefits, such as a faster sample processing and increased taxonomic resolution.

A practical mortality risk score for emergent colectomy.

BACKGROUND: Critically ill patients requiring emergent colectomy have significant mortality risk. OBJECTIVE: A national administrative database was used to compose a simple scoring scheme for predicting in-hospital mortality risk. DESIGN: The 2007 to 2009 Nationwide Inpatient Sample was queried to identify patients requiring nonelective colectomy. Multivariable binary logistic regression analysis was used to identify predictors that increased mortality. Each predictor was given a point value, based on the corresponding logit, the sum of which constituted a risk score. The scoring system was tested by using k-partitions cross-validation. SETTINGS: This study is based on database analysis. PATIENTS: A total of 338,348 cases were identified. Mean age was 64, and 53% of the patients were women. MAIN OUTCOME MEASURES: The primary outcomes measured were mortality and risk score development. RESULTS: The overall mortality risk was 9%. Regression analysis identified the following risk factors and assigned points: acute renal failure (6), hemodialysis (6), age >65 (4), peripheral vascular disease (4), myocardial infarction (4), chronic obstructive pulmonary disease (2), cardiac arrhythmia (1), and congestive heart failure (1). The maximum score observed was 26 (of a possible 28), which corresponded to 100% mortality. Receiver operator characteristic analysis showed an area under the curve of 0.81. LIMITATIONS: This study was limited because of its retrospective nature, and because it used database data with variability in coding among participating institutions. CONCLUSIONS: With the use of a simple 8-variable scoring system, inpatient mortality estimates can be made for patients requiring emergent colectomy. When used judiciously, it can be used as a tool when counseling patients and family both before and after surgery.

Evaluating ethanol-based sample preservation to facilitate use of DNA barcoding in routine freshwater biomonitoring programs using benthic macroinvertebrates.

Molecular methods, such as DNA barcoding, have the potential to enhance biomonitoring programs worldwide. Altering routinely used sample preservation methods to protect DNA from degradation may pose a potential impediment to application of DNA barcoding and metagenomics for biomonitoring using benthic macroinvertebrates. Using higher volumes or concentrations of ethanol, requirements for shorter holding times, or the need to include additional filtering may increase cost and logistical constraints to existing biomonitoring programs. To address this issue we evaluated the efficacy of various ethanol-based sample preservation methods at maintaining DNA integrity. We evaluated a series of methods that were minimally modified from typical field protocols in order to identify an approach that can be readily incorporated into existing monitoring programs. Benthic macroinvertebrates were collected from a minimally disturbed stream in southern California, USA and subjected to one of six preservation treatments. Ten individuals from five taxa were selected from each treatment and processed to produce DNA barcodes from the mitochondrial gene cytochrome c oxidase I (COI). On average, we obtained successful COI sequences (i.e. either full or partial barcodes) for between 93-99% of all specimens across all six treatments. As long as samples were initially preserved in 95% ethanol, successful sequencing of COI barcodes was not affected by a low dilution ratio of 2∶1, transfer to 70% ethanol, presence of abundant organic matter, or holding times of up to six months. Barcoding success varied by taxa, with Leptohyphidae (Ephemeroptera) producing the lowest barcode success rate, most likely due to poor PCR primer efficiency. Differential barcoding success rates have the potential to introduce spurious results. However, routine preservation methods can largely be used without adverse effects on DNA integrity.

Transfer status is a risk factor for increased in-hospital mortality in patients with diverticular hemorrhage.

PURPOSE: Gastrointestinal tract hemorrhage is a common problem accounting for approximately 1 % of hospital admissions. It is estimated that one third of the episodes of lower gastrointestinal hemorrhage are secondary to diverticular disease. Inter-institutional transfer has been associated with delay in care and increased in-hospital mortality. We hypothesized that patients with diverticular hemorrhage that were transferred from an acute care hospital to tertiary care institutions have increased in-hospital morbidity and mortality when compared to primarily admitted patients. MATERIALS AND METHODS: We performed a retrospective analysis of the Nationwide Inpatient Sample for the year 2008. Patients with a primary discharge diagnosis of diverticular hemorrhage were selected. Multivariate logistic regression was used to identify the relationship between transfer status and in-hospital mortality. RESULTS: A total of 99,415 hospitalizations for diverticular hemorrhage were identified. Transferred patients had higher in-hospital mortality rates compared to primarily admitted patients (3.5 vs. 1.8 %, p < 0.001), as well as increased length of stay (8.4 vs. 5.4 days, p < 0.001) and a higher rate of total abdominal colectomy (1.2 vs. 0.6 %, p < 0.001). Multivariate analysis indicated that transfer status was associated with increased in-hospital mortality [OR 1.8, 95 % CI 1.5-2.8, p < 0.001]. CONCLUSIONS: Inter-institutional transfer for diverticular bleeding is associated with increased in-hospital mortality, increased total abdominal colectomy rate, as well as increased economic burden including mean length of stay and total hospital charges. Further prospective studies are needed to analyze the clinical information of patients requiring transfer to another hospital in order to identify those patients who would truly benefit from inter-institutional transfer.

Performance of two Southern California benthic community condition indices using species abundance and presence-only data: relevance to DNA barcoding.

DNA barcoding, as it is currently employed, enhances use of marine benthic macrofauna as environmental condition indicators by improving the speed and accuracy of the underlying taxonomic identifications. The next generation of barcoding applications, processing bulk environmental samples, will likely only provide presence information. However, macrofauna indices presently used to interpret these data are based on species abundances. To assess the importance of this difference, we evaluated the performance of the Southern California Benthic Response Index (BRI) and the AZTI Marine Biotic Index (AMBI) when species abundance data were removed from their calculation. Presence only versions of these two indices were created by eliminating abundance weighting while preserving species identity. Associations between the presence and abundance BRI, and the presence and abundance AMBI were highly significant, with correlation coefficients of 0.99 and 0.81, respectively. The presence versions validated almost equally to the abundance-based indices when applied to the spatial and the temporal monitoring data used to validate the original indices. Simulations in which taxa were systematically removed from calculation of the indices were also conducted to assess how large the barcode library must be for the indices to be effective. Correlation between the BRI-P and BRI remained above 0.9 with only 370 species in the library and reducing the number of species to 450 had almost no effect on correlation between the presence and abundance versions of the AMBI.