Further Distance From Treating Facility is Associated With Advanced Colon Cancer at Presentation and Increased Mortality.

BACKGROUND: Colon cancer outcomes in the United States have improved over the last thirty years. However, there remain significant outcome disparities, especially in rural regions. It is unclear if distance to the treating facility has an independent effect on colon cancer mortality and outcomes. We sought to evaluate whether distance from a treating facility impacts stage at diagnosis and mortality. METHODS: The National Cancer Database (NCDB) was utilized to identify a cohort of adult patients with colon cancer between the years 2013 and 2017 in all regions of the United States. Outcomes measured included colon cancer TNM stage, time to surgery, time to chemotherapy, and overall survival. RESULTS: A total of n = 356,189 patients met inclusion criteria. When controlling for race, education status, insurance status, comorbidities, and income, distance from the treating facility was a significant predictor of stage at presentation with more advanced clinical TNM stage as distance increased (AORs 1.12-1.62, P < .001 for all groups). Longer distance significantly increased the time to surgery (between 5.06 and 14.46 days, P < .001) and overall mortality (HR 1.11-1.28, P < .001). Median survival was 82.4 months for the closest group, versus 75.1 months for the farthest group (P < .001). CONCLUSIONS: Increased distance from the treating facility resulted in a significantly higher stage at presentation, increased time to surgery, and increased mortality. These results suggest that there are significant disparities in access to cancer care for patients who live in rural areas. Targeted interventions by treating facilities are needed to improve screening and timely treatment for rural colon cancer patients.

Alvimopan retains efficacy in patients undergoing colorectal surgery within an established ERAS program.

BACKGROUND: Post-operative ileus and delayed return of gastrointestinal function are complications seen frequently in patients undergoing colorectal surgery. Many enhanced recovery after surgery protocols include alvimopan to inhibit the effects of opiates in the gastrointestinal tract and lidocaine to augment analgesics. Limited data exist regarding alvimopan's efficacy in opiate-sparing regimens. METHODS: This single-center, retrospective cohort analysis was conducted in a randomly selected population of adult patients undergoing colorectal resection between February 2018 and October 2019. Patients meeting inclusion criteria were divided into four groups dependent upon whether or not they received alvimopan (A or a) and/or lidocaine (L or l). The primary endpoint in this study was median time to first bowel movement or discharge, whichever came first. Our secondary endpoint was length of stay. RESULTS: Of the 430 patients evaluated, a total of 192 patients were included in the final evaluation in the following groups: AL (n = 93), Al (n = 34), aL (n = 44), and al (n = 21). A significant difference was found among the groups for the primary outcome of median time to bowel movement or discharge (p = 0.001). Three subsequent pair-wise comparisons resulted in a significant difference in the primary outcome: group AL 39.4 h vs. group aL 54.0 h (p = 0.003), group AL 39.4 h vs. group al 55.4 h (p = 0.001), and group Al 44.9 h vs. group al 55.4 h (p = 0.01). Length of stay was significantly reduced by 1.8 days in groups AL and Al compared to group aL (p < 0.001). CONCLUSION: Treatment with alvimopan resulted in a significant improvement in time to GI recovery and decreased length of stay in an established ERAS program. While lidocaine's reduction in opiates was minimal, the group receiving both alvimopan and lidocaine had the greatest reduction in time to GI recovery and length of stay.

Forty-eight-year-old female MUTYH carrier presenting with five concurrent primary cancers.

BACKGROUND: MUTYH-associated polyposis is a rare disorder resulting from mutations involved in DNA mismatch repair. This results in an increased susceptibility to colonic adenomatosis and other cancers. Studies have examined the resulting frequency of extracolonic manifestations; however, these typically occur alone, concurrently, or temporally separate from an already diagnosed colorectal cancer in individuals with a biallelic mutation. CASE: Reported here is a case of five distinct primary neoplasms presenting simultaneously in a patient monoallelic for an MYH mutation. These neoplasms included squamous cell carcinoma of the vulva, rectal adenocarcinoma, synchronous anal adenocarcinoma, papillary thyroid carcinoma, and ovarian serous psammocarcinoma. Throughout her course, she underwent multiple surgical procedures, neoadjuvant chemoradiation, with further adjuvant therapy, and treatment ongoing. Due to her unique presentation, she underwent genetic testing that demonstrated she was monoallelic for an MYH mutation. CONCLUSION: The patient had a positive response to her treatment and surgical procedures with ongoing adjuvant therapy. She will continue to undergo further genetic testing, and testing for her children is being considered. This case demonstrates a unique presentation associated with a monoallelic MYH mutation that is not described in the current literature and warrants further investigation.

Scaling photosynthetic function and CO2 dynamics from leaf to canopy level for maize - dataset combining diurnal and seasonal measurements of vegetation fluorescence, reflectance and vegetation indices with canopy gross ecosystem productivity.

Recent advances in leaf fluorescence measurements and canopy proximal remote sensing currently enable the non-destructive collection of rich diurnal and seasonal time series, which are required for monitoring vegetation function at the temporal and spatial scales relevant to the natural dynamics of photosynthesis. Remote sensing assessments of vegetation function have traditionally used actively excited foliar chlorophyll fluorescence measurements, canopy optical reflectance data and vegetation indices (VIs), and only recently passive solar induced chlorophyll fluorescence (SIF) measurements. In general, reflectance data are more sensitive to the seasonal variations in canopy chlorophyll content and foliar biomass, while fluorescence observations more closely relate to the dynamic changes in plant photosynthetic function. With this dataset we link leaf level actively excited chlorophyll fluorescence, canopy proximal reflectance and SIF, with eddy covariance measurements of gross ecosystem productivity (GEP). The dataset was collected during the 2017 growing season on maize, using three automated systems (i.e., Monitoring Pulse-Amplitude-Modulation fluorimeter, Moni-PAM; Fluorescence Box, FloX; and from eddy covariance tower). The data were quality checked, filtered and collated to a common 30 minutes timestep. We derived vegetation indices related to canopy functioning (e.g., Photochemical Reflectance Index, PRI; Normalized Difference Vegetation Index, NDVI; Chlorophyll Red-edge, Clre) to investigate how SIF and VIs can be coupled for monitoring vegetation photosynthesis. The raw datasets and the filtered and collated data are provided to enable new processing and analyses.

Effect of Enhanced Recovery After Surgery Protocol Implementation on Cost and Outcomes by Type of Colectomy Performed.

BACKGROUND: Enhanced recovery after surgery (ERAS) protocols are widely utilized for elective colorectal surgery to improve outcomes and decrease costs, but few studies have evaluated the impact of ERAS protocols on cost with respect to anatomic site of resection. This study evaluated the impact of ERAS protocol on elective colon resections by site and longitudinal impact over time. METHODS: A single-center retrospective cohort study of 598 consecutive patients undergoing elective colorectal resection before and after implementation of ERAS protocol from 2013 to 2017 was performed. The primary outcomes were length of stay (LOS) and cost. Comparative and multivariate inferential statistics were used to assess additional outcomes. RESULTS: A total of 598 patients (100 pre-ERAS vs 498 post-ERAS) were evaluated with an overall median LOS of 4 days for right and left colectomies and 3 days for transverse colectomies. When comparing type of resection before and after ERAS protocol introduction, an increased LOS for left hemicolectomies from 3.09 to 4.03 days (P = .047) was noted, with all other comparisons failing to reach statistical significance. Over time, an initial decrease in LOS for MIS approach after protocol introduction was observed; however, this effect diminished in the ensuing years and had no significant effect overall. Total cost of care was significantly increased post-ERAS for all cohorts except transverse colectomies. No further statistically significant differences were found. CONCLUSION: After an initial improvement in outcomes, continued utilization of ERAS protocols demonstrated no improvement in LOS compared to pre-ERAS data and increased cost overall for patients regardless of site of resection.

Predicting and Preventing Postoperative Outcomes.

Complications after colorectal surgery are common. Given the frequency of postoperative complications and their implications on quality of life, it is important to know how to predict and prevent the complications that we encounter. This article aims to provide ways to predict and prevent postoperative complications in colorectal surgery. Here, we review the predictive models, American College of Surgeons National Surgery Quality Improvement Program risk calculator and Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity on their practicality and usefulness. Additionally, this review summarizes nonmodifiable and modifiable risk factors in colorectal surgery, which are important for surgeons to understand to minimize and attempt to avoid postoperative complications as well as providing ways to optimize patients preoperatively. Thus, this review will provide information to surgeons to predict and prevent postoperative complications, how to optimize patients preoperatively and ultimately to help reduce their occurrence.

Evaluating and Exploring Variations in Surgical Resident Emotional Intelligence and Burnout.

OBJECTIVE: Surgery resident burnout rates are on the rise, ranging from 50% to 69%. Burnout is associated with increased risk of error and poorer patient satisfaction. Emotional intelligence (EI) is defined as the capacity to be aware of, control, and express one's emotions, and to handle interpersonal relationships judiciously and empathetically. We seek to evaluate the correlation between EI and burnout temporally as a potential target for education. This may allow us to utilize objective measures to reduce burnout among our residents. DESIGN: A prospective study of general surgery residents at a single institution was performed via self-reporting assessments on personal demographics, the Maslach Burnout Inventory (MBI), and the Scale of Emotional Functioning: Health Service Provider at 3 separate time-points. SETTING: A medium sized academic medical center in Tennessee approved to graduate 6 chief residents per year. PARTICIPANTS: All general surgery residents PGY1 to PGY5 including preliminary residents were given the assessment tools and the option of participating. Research residents were excluded. RESULTS: A total of 86 assessments were completed, including 15 residents who completed all 3 assessments. Changes in the personal achievement (PA) portion of the MBI had the strongest correlation with temporal changes in EI with a Pearson correlation coefficient of 0.606 and 0.616 (p 0.017 and 0.015, respectively). Of the 3 subscales of the MBI, residents had moderate or severe emotional exhaustion for 62% of responses, 73% for depersonalization, and 37% for PA. All categories examined (emotional exhaustion, depersonalization, PA, and EI) saw improvement in scores across 3 administrations. CONCLUSIONS: Improvements in burnout and EI scores were seen across 3 administrations of surveys without any intervention. In the future, assessing PA may have the highest potential to evaluate burnout indirectly. Designing a curriculum for EI may assist with preventing burnout.

Laparoscopic transanal minimally invasive surgery (L-TAMIS) versus robotic TAMIS (R-TAMIS): short-term outcomes and costs of a comparative study.

BACKGROUND: Transanal minimally invasive surgery (TAMIS) has gained worldwide popularity as a method for the local excision of rectal neoplasms. However, it is technically demanding due to limited working space. Robotic TAMIS offers potential enhanced dexterity and ability while allowing for a more aggressive resection with a stable platform. The objective of this study was to review a single institution experience between laparoscopic (L-TAMIS) and robotic TAMIS (R-TAMIS) for treatment of rectal neoplasms and determine if there are significant differences on outcomes. METHODS: Forty consecutive patients with rectal neoplasms underwent L-TAMIS or R-TAMIS by two colorectal surgeons from January 2012 to April 2017. We retrospectively reviewed a prospectively maintained database to analyze demographics, peri-operative data, pathology, post-operative complications, and cost. RESULTS: There were no significant differences between L- and R-TAMIS on patient demographics. R-TAMIS showed a statically significant increase in cost of surgery by $880. Median direct cost of L-TAMIS was $3562 compared to $4440.92 for R-TAMIS (p = 0.04). Wider range of total duration for L-TAMIS is likely due to the variability of body habitus and location of rectal neoplasm, which can significantly limit L-TAMIS compare to R-TAMIS. There was a trend toward decreased blood loss in the R-TAMIS group. Mortality was 0% in both groups. CONCLUSIONS: After reviewing our experience, we conclude there is no significant difference between L- and R-TAMIS other than total direct cost. We confirmed that both L- and R-TAMIS are safe and associated with low morbidity. The limitations of this study include its small sample size. In the future, we hope to show promising data on R-TAMIS with increased sample size and experience, which may allow for transanal resection not previously feasible. Studies with long-term follow-up assessing oncological and functional results will be mandatory.

Individual differences in eyewitness accuracy across multiple lineups of faces.

Theories of face recognition in cognitive psychology stipulate that the hallmark of accurate identification is the ability to recognize a person consistently, across different encounters. In this study, we apply this reasoning to eyewitness identification by assessing the recognition of the same target person repeatedly, over six successive lineups. Such repeat identifications are challenging and can be performed only by a proportion of individuals, both when a target exhibits limited and more substantial variability in appearance across lineups (Experiments 1 and 2). The ability to do so correlates with individual differences in identification accuracy on two established tests of unfamiliar face recognition (Experiment 3). This indicates that most observers have limited facial representations of target persons in eyewitness scenarios, which do not allow for robust identification in most individuals, partly due to limitations in their ability to recognize unfamiliar faces. In turn, these findings suggest that consistency of responses across multiple lineups of faces could be applied to assess which individuals are accurate eyewitnesses.

Gut Microbiota and Colorectal Surgery: Impact on Postoperative Complications.

Colorectal anastomotic leakage is a dreaded complication after colorectal surgery and causes high morbidity and mortality. The pathophysiology of anastomotic healing remains unclear despite numerous studies. In this article, our aim is to provide different perspectives on what is known about the role of the gastrointestinal tract microbiome and its relation to anastomotic integrity.

Prospective Case Series of a Novel Minimally Invasive Bipolar Coagulation System in the Treatment of Grade I and II Internal Hemorrhoids.

Background Existing nonsurgical procedures for the treatment of grade I and II internal hemorrhoids are often painful, technically demanding, and often necessitate multiple applications. This study prospectively assessed the safety and efficacy of the HET Bipolar System, a novel minimally invasive device, in the treatment of symptomatic grade I and II internal hemorrhoids. Methods Patients with symptomatic grade I or II internal hemorrhoids despite medical management underwent hemorrhoidal ligation with the HET Bipolar System. Endpoints included resolution or improvement of hemorrhoidal bleeding and/or prolapse from baseline, recurrent or refractory symptoms, and pain. Results Twenty patients were treated with the HET Bipolar System. Two were lost to follow-up. Refractory or recurrent bleeding was present in 8 of 18 (44.4%), 4 of 11 (36.4%), and 4 of 8 (50.0%) patients, and prolapse was reported by 1 of 18 (5.6%), 4 of 11 (36.4%), and 1/7 (14.3%) of patients at 1, 3, and 6 months, respectively. Bleeding improved from baseline in 88.2%, 81.8%, and 87.5% of patients, and resolution of baseline prolapse was seen in 11 of 11 (100%), 4 of 7 (57.1%), and 5 of 5 (100%) patients at the same intervals. Thirteen of 18 (72.2%) patients did not require additional treatment for their symptoms. Conclusions The HET Bipolar System is safe and easy to use with short-term effectiveness comparable to that of currently used techniques for the treatment of symptomatic grade I and II internal hemorrhoids. It may be an effective alternative to rubber band ligation in patients with larger internal hemorrhoids and those with hemorrhoids close to the dentate line in which banding may produce debilitating pain.

Failing to Prepare Is Preparing to Fail: A Single-Blinded, Randomized Controlled Trial to Determine the Impact of a Preoperative Instructional Video on the Ability of Residents to Perform Laparoscopic Right Colectomy.

BACKGROUND: Laparoscopic colorectal resection is an index case for advanced skills training, yet many residents struggle to reach proficiency by graduation. Current methods to reduce the learning curve for residents remain expensive, time consuming, and poorly validated. OBJECTIVE: The purpose of this study was to assess the impact of the addition of a preprocedural instructional video to improve the ability of a general surgery resident to perform laparoscopic right colectomy when compared with standard preparation. DESIGN: This was a single-blinded, randomized control study. SETTINGS: Four university-affiliated teaching hospitals were included in the study. PARTICIPANTS: General surgery residents in postgraduation years 2 through 5 participated. INTERVENTION: Residents were randomly assigned to preparation with a narrated instructional video versus standard preparation. MAIN OUTCOME MEASURES: Resident performance, scored by a previously validated global assessment scale, was measured. RESULTS: Fifty-four residents were included. Half (n = 27) were randomly assigned to view the training video and half (n = 27) to standard preparation. There were no differences between groups in terms of training level or previous operative experience or in patient demographics (all p > 0.05). Groups were similar in the percentage of the case completed by residents (p = 0.39) and operative time (p = 0.74). Residents in the video group scored significantly higher in total score (mean: 46.8 vs 42.3; p = 0.002), as well as subsections directly measuring laparoscopic skill (vascular control mean: 11.3 vs 9.7, p < 0.001; mobilization mean: 7.6 vs. 7.0, p = 0.03) and overall performance score (mean: 4.0 vs 3.1; p < 0.001). Statistical significance persisted across training levels. LIMITATIONS: There is potential for Hawthorne effect, and the study is underpowered at the individual postgraduate year level. CONCLUSIONS: The simple addition of a brief, narrated preprocedural video to general surgery resident case preparation significantly increased trainee ability to successfully perform a laparoscopic right colectomy. In an era of shortened hours and less exposure to cases, incorporating a brief but effective instructional video before surgery may improve the learning curve of trainees and ultimately improve safety.

Staff perceptions of palliative care in a public Australian, metropolitan emergency department.

OBJECTIVE: The primary aim was to investigate staff experiences and attitudes towards palliative care provision in a public metropolitan ED. METHODS: Using a previously validated survey tool, data were collected from ED clinical staff using Likert-type, open-ended and dichotomous items asking about perceptions of palliative care and education needs. Comparisons were made between nursing and medical staff. RESULTS: Medical staff and nurses' perceptions of palliative care were similar, differing on only 10 of 37 (Likert) items. All staff reported confidence with symptom management, whereas medical staff felt more confident with decision-oriented communication and nurses were more supportive of nasogastric feeding. Staff were moderately accurate in determining the five most common causes of death. Four out of five conditions selected as appropriate for palliative care were cancer diagnoses. End-of-life communication and ethical issues were the two most frequently requested areas for further education. CONCLUSIONS: Our study suggests that overall ED staff were confident regarding symptom management in palliative care. Cancer diagnoses were overrepresented in both the top five causes of death and conditions most appropriate for a palliative approach, suggesting that staff might underestimate the role of a palliative approach in non-cancer diagnoses. Areas suggested for further education include communication and ethical issues surrounding end-of-life care.

High-resolution anoscopy or expectant management for anal intraepithelial neoplasia for the prevention of anal cancer: is there really a difference?

BACKGROUND: High-resolution anoscopy has been shown to improve identification of anal intraepithelial neoplasia but a reduction in progression to anal squamous-cell cancer has not been substantiated when serial high-resolution anoscopy is compared with traditional expectant management. OBJECTIVE: The aim of this study was to compare high-resolution anoscopy versus expectant management for the surveillance of anal intraepithelial neoplasia and the prevention of anal cancer. DESIGN: This is a retrospective review of all patients who presented with anal squamous dysplasia, positive anal Pap smears, or anal squamous-cell cancer from 2007 to 2013. SETTING: This study was performed in the colorectal department of a university-affiliated, tertiary care hospital. PATIENTS: Included patients had biopsy-proven anal intraepithelial neoplasia from 2007 to 2013. INTERVENTIONS: Patients were treated with high-resolution anoscopy with ablation or standard anoscopy with ablation. Both groups were treated with imiquimod and followed every 6 months indefinitely. MAIN OUTCOME MEASURES: The incidence of anal squamous-cell cancer in each group was the primary end point. RESULTS: From 2007 to 2013, 424 patients with anal squamous dysplasia were seen in the clinic (high-resolution anoscopy, 220; expectant management, 204). Three patients (high-resolution anoscopy, 1; expectant management, 2) progressed to anal squamous-cell cancer; 2 were noncompliant with follow-up and with HIV treatment, and the third was allergic to imiquimod and refused to take topical 5-fluorouracil. The 5-year progression rate was 6.0% (95% CI, 1.5-24.6) for expectant management and 4.5% (95% CI, 0.7-30.8) for high-resolution anoscopy (p = 0.37). LIMITATIONS: This was a retrospective review. There is potential for selection and referral bias. Because of the rarity of the outcome, the study may be underpowered. CONCLUSIONS: Patients with squamous-cell dysplasia followed with expectant management or high-resolution anoscopy rarely develop squamous-cell cancer if they are compliant with the protocol. The cost, morbidity, and value of high-resolution anoscopy should be further evaluated in lieu of these findings.

Improving outcomes and cost-effectiveness of colorectal surgery.

In order to truly make an impact on improving the cost effectiveness, and most importantly, the outcomes of patients undergoing colorectal surgery, all aspects of care need to be scrutinized, re-evaluated, and refined. To accomplish this, everything from the way we train surgeons to the adoption of a minimally invasive approach for colorectal disease, along with the use of adjunct intraoperative measures to decrease morbidity and mortality, may all need to be incorporated within an ERAS program. Only then will this approach lead the provider to a patient-centric care plan which can successfully reduce metrics such as morbidity, mortality, and length of stay (even with the obligatory readmission rate) and provide it all at a lower cost of care.

Psycho-educational support for relatives of people with a recent diagnosis of mild to moderate dementia: an evaluation of a 'Course for Carers'.

Currently there are 820,000 people with dementia in the UK, a figure projected to reach 1.7 million by 2050. Policy and practice emphasis on early intervention in dementia and support of family carers foreground a need to explore service efficacy for relatives of those with a recent diagnosis. Existing evidence suggests that psycho-educational interventions can significantly enhance carer well being especially when well targeted and group based. A rolling programme of seven psycho-educational Courses for 'new carers' in one area of England was the subject of a systematic evaluation incorporating a quantitative rating scale and qualitative data. Findings suggest that the Courses achieved a number of intersecting aims: they provided psychological support; offered advice; enhanced coping skills; boosted confidence; increased knowledge; and prepared the carer for the future. That the Courses were designed and delivered by specialist staff - primarily psychologists, offered a social dimension, were time limited and free are noteworthy features. The evaluation suggests that as a model the Course has considerable short and longer term preventive potential; also that it could be replicated elsewhere in the country and achieve similar outcomes.

Preoperative classification of pancreatic cystic neoplasms: the clinical significance of diagnostic inaccuracy.

BACKGROUND: The potential for malignant transformation varies among pancreatic cystic neoplasms (PCN) subtypes. Imaging and cyst fluid analysis are used to identify premalignant or malignant cases that should undergo operative resection, but the accuracy of operative decision-making process is unclear. The objective of this study was to characterize misdiagnoses of PCN and determine how often operations are undertaken for benign, non-premalignant disease. METHODS: A retrospective analysis of patients undergoing pancreatic resection for the preoperative diagnosis of PCN was undertaken. Preoperative and pathological diagnoses were compared to measure diagnostic accuracy. RESULTS: Between 1999 and 2011, 74 patients underwent pancreatic resection for the preoperative diagnosis of PCN. Preoperative classification of mucinous vs. non-mucinous PCN was correct in 74%. The specific preoperative PCN diagnosis was correct in 47%, but half of incorrect preoperative diagnoses were clinically equivalent to the pathological diagnoses. The likelihood that the pathological diagnosis was of higher malignant potential than the preoperative diagnosis was 7%. In 20% of cases, the preoperative diagnosis was premalignant or malignant, but the pathological diagnosis was benign. Diagnostic accuracy and the rate of undercall diagnoses and overcall operations did not change with the use of EUS or during the time period of this analysis. CONCLUSIONS: Precise, preoperative classification of PCN is frequently incorrect but results in appropriate clinical decision-making in three-quarters of cases. However, one in five pancreatic resections performed for PCN was for benign disease with no malignant potential. An appreciation for the rate of diagnostic inaccuracies should inform our operative management of PCN.

Memory T cells are uniquely resistant to melanoma-induced suppression.

We have previously observed that in vivo exposure to growing melanoma tumors fundamentally alters activated T cell homeostasis by suppressing the ability of naïve T cells to undergo antigen-driven proliferative expansion. We hypothesized that exposure of T cells in later stages of differentiation to melanoma would have similar suppressive consequences. C57BL/6 mice were inoculated with media or syngeneic B16F10 melanoma tumors 8 or 60 days after infection with lymphocytic choriomeningitis virus (LCMV), and splenic populations of LCMV-specific T cells were quantified using flow cytometry 18 days after tumor inoculation. Inoculation with melanoma on post-infection day 8 potentiated the contraction of previously activated T cells. This enhanced contraction was associated with increased apoptotic susceptibility among T cells from tumor-bearing mice. In contrast, inoculation with melanoma on post-infection day 60 did not affect the ability of previously established memory T cells to maintain themselves in stable numbers. In addition, the ability of previously established memory T cells to respond to LCMV challenge was unaffected by melanoma. Following adoptive transfer into melanoma-bearing mice, tumor-specific memory T cells were significantly more effective at controlling melanoma growth than equivalent numbers of tumor-specific effector T cells. These observations suggest that memory T cells are uniquely resistant to suppressive influences exerted by melanoma on activated T cell homeostasis; these findings may have implications for T cell-based cancer immunotherapy.

Comparison of field-scale herbicide runoff and volatilization losses: an eight-year field investigation.

An 8-yr study was conducted to better understand factors influencing year-to-year variability in field-scale herbicide volatilization and surface runoff losses. The 21-ha research site is located at the USDA-ARS Beltsville Agricultural Research Center in Beltsville, MD. Site location, herbicide formulations, and agricultural management practices remained unchanged throughout the duration of the study. Metolachlor [2-chloro--(2-ethyl-6-methylphenyl)--(2-methoxy-1-methylethyl) acetamide] and atrazine [6-chloro--ethyl--(1-methylethyl)-1,3,5-triazine-2,4-diamine] were coapplied as a surface broadcast spray. Herbicide runoff was monitored from a month before application through harvest. A flux gradient technique was used to compute volatilization fluxes for the first 5 d after application using herbicide concentration profiles and turbulent fluxes of heat and water vapor as determined from eddy covariance measurements. Results demonstrated that volatilization losses for these two herbicides were significantly greater than runoff losses ( < 0.007), even though both have relatively low vapor pressures. The largest annual runoff loss for metolachlor never exceeded 2.5%, whereas atrazine runoff never exceeded 3% of that applied. On the other hand, herbicide cumulative volatilization losses after 5 d ranged from about 5 to 63% of that applied for metolachlor and about 2 to 12% of that applied for atrazine. Additionally, daytime herbicide volatilization losses were significantly greater than nighttime vapor losses ( < 0.05). This research confirmed that vapor losses for some commonly used herbicides frequently exceeds runoff losses and herbicide vapor losses on the same site and with the same management practices can vary significantly year to year depending on local environmental conditions.