Hypothalamic Transcriptome Response To Simulated Diel Earthen Pond Hypoxia Cycles In Channel Catfish (Ictalurus punctatus).

Commercial culture of channel catfish (Ictalurus punctatus) occurs in earthen ponds that are characterized by diel swings in dissolved oxygen concentration that can fall to severe levels of hypoxia which can suppress appetite and lead to suboptimal growth. Given the significance of the hypothalamus in regulating these processes in other fishes, an investigation into the hypothalamus transcriptome was conducted to identify specific genes and expression patterns responding to hypoxia. Channel catfish in normoxic water were compared to catfish subjected to 12 hours of hypoxia (20% oxygen saturation; 1.8 mg O2/L; 27 °C) followed by 12 hours of recovery in normoxia to mimic 24-hours in a catfish aquaculture pond. Fish were sampled at 0-, 6-, 12-, 18-, and 24-hour time points, with the 6- and 12-hour samplings occurring during hypoxia. A total of 190 genes were differentially expressed during the experiment, with most occurring during hypoxia and returning to baseline values within 6 hours of normoxia. Differentially expressed genes were sorted by function into Gene Ontology biological processes and revealed that most were categorized as "response to hypoxia", "sprouting angiogenesis", and "cellular response to xenobiotic stimulus". The patterns of gene expression reported here suggest that transcriptome responses to hypoxia are broad and quickly reversibly with the onset of normoxia. Although no genes commonly reported to modulate appetite were found to be differentially expressed in this experiment, several candidates were identified for future studies investigating the interplay between hypoxia and appetite in channel catfish, including adm, igfbp1a, igfbp7, and stc2b.

Contemporary trends and outcomes after liver transplantation and resection for intrahepatic cholangiocarcinoma.

BACKGROUND: Liver transplantation (LT) has been shown to be superior to resection in highly selected patients with perihilar cholangiocarcinoma (CCA), yet has traditionally been contraindicated for intrahepatic CCA (iCCA). Herein, we aimed to examine contemporary trends and outcomes for surgical resection and LT for iCCA. METHODS: The National Cancer Database was queried for patients presenting with stage I-III iCCA between 2010 and 2018 who underwent resection or LT. Overall survival (OS) was compared with Kaplan-Meier and multivariable Cox proportional hazards methods stratified by management. Secondary analysis of patients undergoing transplant for CCA was performed with the United Network for Organ Sharing database. RESULTS: Of 2565 patients, 2412 (94.0%) underwent resection and 153 (5.96%) LT of whom 84 (54.9%) received neoadjuvant therapy. Utilization of LT remained between 3.9% and 7.8% annually. Unadjusted 5-year OS was higher for LT than resection (59.8% vs 39.9%, P = .0067), yet adjusted analysis revealed no significant difference in mortality (hazard ratio, 0.91; 95% CI, 0.66-1.27; P = .58). On secondary analysis including 437 patients with all subtypes of CCA, unadjusted 5-year OS was higher for non-CCA indications (79% vs 52%-54%, P < .001). CONCLUSION: Utilization of LT for iCCA remains low and many cases are likely incidental. Although partial hepatectomy remains the standard of care for patients with resectable disease, our findings suggest that highly selected patients with unresectable iCCA may achieve favorable outcomes after LT. Granular, prospective data are needed to identify patients most likely to benefit from transplant and allocate scarce liver grafts.

Comprehensive Assessment of the Intrinsic Pancreatic Microbiome.

OBJECTIVE: We sought to comprehensively profile tissue and cyst fluid in patients with benign, precancerous, and cancerous conditions of the pancreas to characterize the intrinsic pancreatic microbiome. SUMMARY BACKGROUND DATA: Small studies in pancreatic ductal adenocarcinoma (PDAC) and intraductal papillary mucinous neoplasm (IPMN) have suggested that intra-pancreatic microbial dysbiosis may drive malignant transformation. METHODS: Pancreatic samples were collected at the time of resection from 109 patients. Samples included tumor tissue (control, n=20; IPMN, n=20; PDAC, n=19) and pancreatic cyst fluid (IPMN, n=30; SCA, n=10; MCN, n=10). Assessment of bacterial DNA by quantitative PCR and 16S ribosomal RNA gene sequencing was performed. Downstream analyses determined the relative abundances of individual taxa between groups and compared intergroup diversity. Whole-genome sequencing data from 140 patients with PDAC in the National Cancer Institute's Clinical Proteomic Tumor Analysis Consortium (CPTAC) were analyzed to validate findings. RESULTS: Sequencing of pancreatic tissue yielded few microbial reads regardless of diagnosis, and analysis of pancreatic tissue showed no difference in the abundance and composition of bacterial taxa between normal pancreas, IPMN, or PDAC groups. Low-grade dysplasia (LGD) and high-grade dysplasia (HGD) IPMN were characterized by low bacterial abundances with no difference in tissue composition and a slight increase in Pseudomonas and Sediminibacterium in HGD cyst fluid. Decontamination analysis using the CPTAC database confirmed a low-biomass, low-diversity intrinsic pancreatic microbiome that did not differ by pathology. CONCLUSIONS: Our analysis of the pancreatic microbiome demonstrated very low intrinsic biomass that is relatively conserved across diverse neoplastic conditions and thus unlikely to drive malignant transformation.

The Value of Textbook Outcome in Benchmarking Pancreatoduodenectomy for Nonfunctioning Pancreatic Neuroendocrine Tumors.

BACKGROUND: Textbook outcome (TO) is a composite variable that can define the quality of pancreatic surgery. The aim of this study is to evaluate TO after pancreatoduodenectomy (PD) for nonfunctioning pancreatic neuroendocrine tumors (NF-PanNETs). PATIENTS AND METHODS: All patients who underwent PD for NF-PanNETs (2007-2016) in different centers were included in this retrospective study. TO was defined as the absence of severe postoperative complications and mortality, length of hospital stay ≤ 19 days, R0 resection, and at least 12 lymph nodes harvested. RESULTS: Overall, 477 patients were included. The TO rate was 32%. Tumor size [odds ratio (OR) 1.696; p = 0.013], a minimally invasive approach (OR 12.896; p = 0.001), and surgical volume (OR 2.062; p = 0.023) were independent predictors of TO. The annual frequency of PDs increased over time as well as the overall rate of TO. At a median follow-up of 44 months, patients who achieved TO had similar disease-free (p = 0.487) and overall survival (p = 0.433) rates compared with patients who did not achieve TO. TO rate in patients with NF-PanNET > 2 cm was 35% versus 27% in patients with NF-PanNET ≤ 2 cm (p = 0.044). Considering only NF-PanNETs > 2 cm, patients with TO and those without TO had comparable 5-year overall survival rates (p = 0.766) CONCLUSIONS: TO is achieved in one-third of patients after PD for NF-PanNETs and is not associated with a benefit in terms of long-term survival.

An investigation of gill and blood carbonic anhydrase characteristics in three basal actinopterygian species: alligator gar (Atractosteus spatula), white sturgeon (Acipenser transmontanus) and Senegal bichir (Polypterus senegalus).

Many teleosts possess a unique set of respiratory characteristics allowing enhanced oxygen unloading to the tissues during stress. This system comprises three major components: highly pH sensitive haemoglobins (large Bohr and Root effects), rapid red blood cell (RBC) intracellular pH (pHi) protection, and a heterogeneous distribution of membrane-bound plasma-accessible carbonic anhydrase (paCA; absence in the gills). The first two components have received considerable research effort; however, the evolutionary loss of branchial paCA has received little attention. In the current study, we investigated the availability of branchial membrane-bound CA, along with several other CA-related characteristics in species belonging to three basal actinopterygian groups: the Lepisosteiformes, Acipenseriformes and Polypteriformes to assess the earlier hypothesis that Root effect haemoglobins constrain branchial paCA availability. We present the first evidence suggesting branchial membrane-bound CA presence in a basal actinopterygian species: the Senegal bichir (Polypterus senegalus) and show that like the teleosts, white sturgeon (Acipenser transmontanus) and alligator gar (Atractosteus spatula) do not possess branchial membrane-bound CA. We discuss the varying respiratory strategies for these species and propose that branchial paCA may have been lost much earlier than previously thought, likely in relation to the changes in haemoglobin buffer capacity associated with the increasing magnitude of the Bohr effect. The findings described here represent an important advancement in our understanding of the evolution of the unique system of enhanced oxygen unloading thought to be present in most teleosts, a group that encompasses half of all vertebrates.

Simple versus radical cholecystectomy and survival for pathologic stage T1B gallbladder cancer.

BACKGROUND: Radical cholecystectomy is recommended for T1B and greater gallbladder cancer, however, there are conflicting reports on the utility of extended resection for T1B disease. Herein, we characterize outcomes following simple and radical cholecystectomy for pathologic stage T1B gallbladder cancer. METHODS: The National Cancer Database (NCDB) was queried for patients with pathologic T1B gallbladder cancer diagnosed from 2004 to 2018. Patients were stratified by surgical management. Overall survival (OS) was compared with Kaplan-Meier and multivariable Cox proportional hazards methods. RESULTS: Altogether, 950 patients were identified with pathologic T1B gallbladder cancer: 187 (19.7 %) receiving simple and 763 (80.3 %) radical cholecystectomy. Median OS was 89.5 (95 % CI 62.5-137) and 91.4 (95 % CI 75.9-112) months for simple and radical cholecystectomy, respectively (log-rank p = 0.55). Receipt of simple cholecystectomy was not associated with greater hazard of mortality compared to radical cholecystectomy (HR 1.23, 95 % CI 0.95-1.59, p = 0.12). DISCUSSION: In this analysis, we report comparable outcomes with simple cholecystectomy among patients with pathologic T1B gallbladder cancer. These findings suggest that highly selected patients, such as those with R0 resection and imaging at low risk for residual disease and/or nodal metastasis, may not benefit from extended resection; however, radical cholecystectomy remains standard of care until prospective validation can be achieved.

Concordance in Oncogenic Alterations Between the Primary Tumor and Advanced Disease: Insights Into the Heterogeneity of Intrahepatic Cholangiocarcinoma.

PURPOSE: Intrahepatic cholangiocarcinoma (ICCA) is characterized by significant phenotypic and clinical heterogeneities and poor response to systemic therapy, potentially related to underlying heterogeneity in oncogenic alterations. We aimed to characterize the genomic heterogeneity between primary tumors and advanced disease in patients with ICCA. METHODS: Biopsy-proven CCA specimens (primary tumor and paired advanced disease [metastatic disease, progressive disease on systemic therapy, or postoperative recurrence]) from two institutions were subjected to targeted next-generation sequencing. Overall concordance (oncogenic driver mutations, copy number alterations, and fusion events) and mutational concordance (only oncogenic mutations) were compared across paired samples. A subgroup analysis was performed on the basis of exposure to systemic therapy. Patients with extrahepatic CCA (ECCA) were included as a comparison group. RESULTS: Sample pairs from 65 patients with ICCA (n = 54) and ECCA (n = 11) were analyzed. The median time between sample collection was 19.6 months (range, 2.7-122.9). For the entire cohort, the overall oncogenic concordance was 49% and the mutational concordance was 62% between primary and advanced disease samples. Subgroup analyses of ICCA and ECCA revealed overall/mutational concordance rates of 47%/58% and 60%/84%, respectively. Oncogenic concordance was similarly low for pairs exposed to systemic therapy between sample collections (n = 50, 53% overall, 68% mutational). In patients treated with targeted therapy for IDH1/2 alterations (n = 6) or FGFR2 fusions (n = 3), there was 100% concordance between the primary and advanced disease specimens. In two patients, FGFR2 (n = 1) and IDH1 (n = 1) alterations were detected de novo in the advanced disease specimens. CONCLUSION: The results reflect a high degree of heterogeneity in ICCA and argue for reassessment of the dominant driver mutations with change in disease status.

Initial Report: Personalized Circulating Tumor DNA and Survival in Patients with Resectable Pancreatic Cancer.

ABSTRACT: BACKGROUND: Pancreatic adenocarcinoma (PDAC) is highly lethal with up to 80% of resected patients experiencing disease recurrence within 2 years (Watanabe, Nakamura, Kimura et al in Int J Mol Sci 23(19):11521, 2022). Cross-sectional imaging and serum tumor markers are used for monitoring post-operative recurrence; however, both have significant limitations (Edland, Tjensvoll, Oltedal et al in Mol Oncol 17:1857-1870, 2023). Circulating tumor DNA (ctDNA) has emerged as a valuable prognostic tool to measure molecular residual disease (MRD) and predict recurrence in solid tumors (Watanabe, Nakamura, Kimura et al in Int J Mol Sci 23(19):11521, 2022). In this study, we evaluated the feasibility of a personalized, tumor-informed ctDNA assay to detect recurrence prior to standard surveillance tools in patients with PDAC. PATIENTS AND METHODS: After Institutional Review Board (IRB) approval (Pro00106870), we assessed serial ctDNA measurements (n = 177) from 35 patients with resectable PDAC treated by either upfront resection or neoadjuvant chemotherapy. Plasma samples (median 4 ml, interquartile range 0.6-5.9 ml) were isolated from blood collected in EDTA tubes and banked at diagnosis, during neoadjuvant therapy if applicable, on the day of surgery, and every 2-3 months postoperatively. A tumor-informed assay (Signatera™, Natera, Inc.) that tracks up to 16 individual-specific, somatic single nucleotide variants in the corresponding patient's plasma samples were used for ctDNA detection. Survival was calculated using Kaplan-Meier curves, and significance was determined with the log-rank test. RESULTS: Personalized ctDNA assays were successfully designed for all patients (with 32/35 patients having 16-plex assays). Median follow-up from initial treatment was 13 months (range 1-26 months; Table 1). ctDNA-positivity at any time point was observed in 40% (14/35) of patients. During the follow-up period, 18 patients (51%) developed radiographic evidence of recurrence after a median of 9 months of follow-up (range 1-26 months). At the time of radiographic recurrence, 50% (9/18) of patients were ctDNA-positive. During the immediate postoperative period (up to 9 weeks post-surgery), RFS and OS were significantly inferior in patients who were ctDNA-positive versus ctDNA-negative (RFS 97 versus 297 days, p < 0.001; OS 110 versus 381 days, p < 0.001; Fig. 1). Table 1 Cohort demographics (N = 35); patient demographics, tumor characteristics, and survival Gender (%) Female 17 (49%) Male 18 (51%) Median age (IQR) 70 years (65-75 years) Neoadjuvant treatment (%) 11 (31%) Median sample plasma volume (IQR) 4.0 mL (0.6-5.9 mL) Median follow-up (range) 13 months (1-26 months) Median initial CA 19-9 in U/mL (IQR) 56 (18-160) Median tumor size in cm (IQR) 2.5 (1.8-3.3) Median number of positive lymph nodes (IQR) 1 (0-3) Median recurrence-free survival 9.4 months Median overall survival N/A (not reached) Fig. 1 a Overview plot showing longitudinal ctDNA status, treatment regimen, and clinical outcomes for each patient (N = 35); median follow-up from the start of the neoadjuvant therapy/surgery was 13 months (range 1-26 months); ctDNA at any time point was 40% (14/35); out of the 35 patients, 18 (51%) developed radiographic evidence of recurrence (median RFS: 9 months), and of these 18 patients with clinical recurrence, 9 (50%) were ctDNA-positive and the remaining ctDNA-negative; notably, all ctDNA-negative patients with recurrence had suboptimal plasma volume available for ctDNA analysis; b, c Kaplan-Meier estimates representing the association of ctDNA status with (b) RFS and (c) OS, at MRD time point (9 weeks post-surgery) DISCUSSION: Our study demonstrates the feasibility of tumor-informed ctDNA-based MRD testing in resectable PDAC and shows that MRD detected by ctDNA within the immediate postoperative period portends a dismal prognosis. This information is valuable for both patients and clinicians in setting prognostic expectations.

Effect of hypoxia duration and pattern on channel Catfish (Ictalurus punctatus) neuropeptide gene expression and hematology.

Commercial aquaculture production of channel catfish (Ictalurus punctatus) occurs in shallow ponds with daily cycling of dissolved oxygen concentration ranging from supersaturation to severe hypoxia. Once daily minimum dissolved oxygen concentration falls below 3.0 mg O2/L, channel catfish have a reduced appetite, leading to reduced growth rates. In other fishes, upregulation of the neuropeptides corticotropin-releasing factor (CRF) and urotensin I (UI) have been implicated as initiating the mechanism responsible for decreasing appetite once an environmental stressor is detected. Channel catfish maintained at 27 °C in aquaria were subjected to varying durations and patterns of hypoxia (1.75 ± 0.07 mg O2/L) to evaluate underlying physiological responses to hypoxia and determine if hypothalamic CRF and UI are responsible for hypoxia-induced anorexia in channel catfish. During a short exposure to hypoxia (12 h), venous PO2 was significantly lower within 6 h and was coupled with an increase of hematocrit and decrease of blood osmolality, yet all responses reversed within 12 h after returning to normoxia. When this pattern of hypoxia and normoxia was repeated cyclically for 5 days, these physiological responses repeated daily. Extended periods of hypoxia (5 days) resulted in similar hematological responses, which did not recover to baseline values during the hypoxia exposure. This study did not find a significant change in hypothalamic transcription of CRF and UI during hypoxia challenges but did identify multiple physiological adaptive responses that work together to reduce the severity of experimentally induced hypoxia in channel catfish.

Tumor size and survival in intrahepatic cholangiocarcinoma treated with surgical resection or ablation.

OBJECTIVES: We performed a retrospective analysis within a national cancer registry on outcomes following resection or ablation for intrahepatic cholangiocarcinoma (iCCA). METHODS: The National Cancer Database was queried for patients with clinical stage I-III iCCA diagnosed during 2010-2018, who underwent resection or ablation. Overall survival (OS) was compared with Kaplan-Meier and multivariable Cox proportional hazards methods. RESULTS: Of 2140 patients, 1877 (87.7%) underwent resection and 263 (12.3%) underwent ablation, with median tumor sizes of 5.5 and 3 cm, respectively. Overall, resection was associated with greater median OS (41.2 months (95% confidence interval [95% CI]: 37.6-46.2) vs. 28 months (95% CI: 15.9-28.6) on univariable analysis (p < 0.0001). There was no significant difference on multivariable analysis (p = 0.42); however, there was a significant interaction between tumor size and management. On subgroup analysis of patients with tumors <3 cm, there was no difference in OS between resection versus ablation. However, ablation was associated with increased mortality for tumors ≥3 cm. CONCLUSION: Although resection is associated with improved OS for tumors ≥3 cm, we observed no difference in survival between management strategies for tumors < 3 cm. Ablation may be an alternative therapeutic strategy for small iCCA, particularly in patients at risk for high surgical morbidity.

Development of a prospective biliary dashboard to compare performance and surgical cost.

BACKGROUND: Transparency around surgeon level data may align healthcare delivery with quality care for patients. Biliary surgery includes numerous procedures performed by both general surgeons and subspecialists alike. Cholecystectomy is a common surgical procedure and an optimal cohort to measure quality outcomes within a healthcare system. METHODS: Data were collected for 5084 biliary operations performed by 68 surgeons in 11 surgical divisions in a health system including a tertiary academic hospital, two regional community hospitals, and two ambulatory surgery centers. A privacy protected dashboard was developed to compare surgeon performance and cost between July 2018 and June 2022. A sample cohort of patients ≥ 18 years who underwent cholecystectomy were compared by operative time, cost, and 30-day outcomes. RESULTS: Over 4 years, 4568 cholecystectomy procedures were performed by 57 surgeons. Operations were done by 57 surgeons in four divisions and included 3846 (84.2%) laparoscopic cholecystectomies, 601 (13.2%) laparoscopic cholecystectomies with cholangiogram, and 121 (2.6%) open cholecystectomies. Patients were admitted from the emergency room in 2179 (47.7%) cases while 2389 (52.3%) cases were performed in the ambulatory setting. Individual surgeons were compared to peers for volume, intraoperative data, cost, and outcomes. Cost was lowest at ambulatory surgery centers, yet only 4.2% of elective procedures were performed at these facilities. Prepackaged kits with indocyanine green were more expensive than cholangiograms that used iodinated contrast. The rate of emergency department visits was lowest when cases were performed at ambulatory surgery centers. CONCLUSION: Data generated from clinical dashboards can inform surgeons as to how they compare to peers regarding quality metrics such as cost, time, and complications. In turn, this may guide strategies to standardize care, optimize efficiency, provide cost savings, and improve outcomes for cholecystectomy procedures. Future application of clinical dashboards can assist surgeons and administrators to define value-based care.

Functional reprogramming of peripheral blood monocytes by soluble mediators in patients with pancreatic cancer and intraductal papillary mucinous neoplasms.

Background: Monocytes and monocyte-derived tumor infiltrating cells have been implicated in the immunosuppression and immune evasion associated with pancreatic adenocarcinoma (PDAC). Yet, precisely how monocytes in the periphery and tumor microenvironment in patients with intraductal papillary mucinous neoplasm (IPMN), a precursor lesion to PDAC, change during disease progression has not been defined. Here we functionally profiled the peripheral immune system and characterized the tumor microenvironment of patients with both IPMN and PDAC. We also tested if sera from patients with IPMN and PDAC functionally reprogram monocytes relative to that of healthy donors. Methods: Pancreatic tissue and peripheral blood were collected at the time of resection from 16 patients with IPMN and 32 patients with PDAC. Peripheral blood and pancreatic tissue/tumor were immunophenotyped using flow cytometry. Whole blood was plated and incubated with R848 (a TLR 7/8 agonist) or LPS (a TLR4 agonist) for 6 hours and TNF expression in monocytes was measured by flow cytometry to measure monocyte activation. To test if TLR sensitivity is determined by factors in patient sera, we preconditioned healthy donor monocytes in serum from PDAC (n=23), IPMN (n=15), or age-matched healthy donors (n=10) followed by in vitro stimulation with R848 or LPS and multiplex cytokine measurements in the supernatant. Results: TNF expression in R848-stimulated peripheral blood monocytes was higher in patients with low grade vs high grade IPMN (65% vs 32%, p = 0.03) and stage 1 vs stage 2/3 PDAC (58% vs 42%, p = 0.03), this was not observed after LPS stimulation. TLR activation correlated with increasing grade of dysplasia from low grade IPMN to high grade IPMN. Serum from patients with IPMN and PDAC recapitulated suppression of TNF induction after R848 stimulation in naïve, healthy donor monocytes. Conclusion: Peripheral blood monocyte TNF secretion inversely correlates with the degree of dysplasia in IPMN and cancer stage in PDAC, suggesting innate immune reprogramming as IPMNs progress to invasive disease. These effects are, at least in part, mediated by soluble mediators in sera.

Comparing Survival After Resection, Ablation, and Radiation in Small Intrahepatic Cholangiocarcinoma.

BACKGROUND: Hepatectomy is the cornerstone of curative-intent treatment for intrahepatic cholangiocarcinoma (ICC). However, in patients unable to be resected, data comparing efficacy of alternatives including thermal ablation and radiation therapy (RT) remain limited. Herein, we compared survival between resection and other liver-directed therapies for small ICC within a national cancer registry. PATIENTS AND METHODS: Patients with clinical stage I-III ICC < 3 cm diagnosed 2010-2018 who underwent resection, ablation, or RT were identified in the National Cancer Database. Overall survival (OS) was compared using Kaplan-Meier and multivariable Cox proportional hazards methods. RESULTS: Of 545 patients, 297 (54.5%) underwent resection, 114 (20.9%) ablation, and 134 (24.6%) RT. Median OS was similar between resection and ablation [50.5 months, 95% confidence interval (CI) 37.5-73.9; 39.5 months, 95% CI 28.7-58.4, p = 0.14], both exceeding that of RT (20.9 months, 95% CI 14.1-28.3). RT patients had high rates of stage III disease (10.4% RT vs. 1.8% ablation vs. 11.8% resection, p < 0.001), but the lowest rates of chemotherapy utilization (9.0% RT vs. 15.8% ablation vs. 38.7% resection, p < 0.001). In multivariable analysis, resection and ablation were associated with reduced mortality compared with RT [hazard ratio (HR) 0.44, 95% CI 0.33-0.58 and HR 0.53, 95% CI 0.38-0.75, p < 0.001, respectively]. CONCLUSION: Resection and ablation were associated with improved survival in patients with ICC < 3 cm compared with RT. Acknowledging confounders, anatomic constraints of ablation, limitations of available data, and need for prospective study, these results favor ablation in small ICC where resection is not feasible.

Development, Deployment, and Implementation of a Machine Learning Surgical Case Length Prediction Model and Prospective Evaluation.

OBJECTIVE: To implement a machine learning model using only the restricted data available at case creation time to predict surgical case length for multiple services at different locations. BACKGROUND: The operating room is one of the most expensive resources in a health system, estimated to cost $22 to $133 per minute and generate about 40% of hospital revenue. Accurate prediction of surgical case length is necessary for efficient scheduling and cost-effective utilization of the operating room and other resources. METHODS: We introduced a similarity cascade to capture the complexity of cases and surgeon influence on the case length and incorporated that into a gradient-boosting machine learning model. The model loss function was customized to improve the balance between over- and under-prediction of the case length. A production pipeline was created to seamlessly deploy and implement the model across our institution. RESULTS: The prospective analysis showed that the model output was gradually adopted by the schedulers and outperformed the scheduler-predicted case length from August to December 2022. In 33,815 surgical cases across outpatient and inpatient platforms, the operational implementation predicted 11.2% fewer underpredicted cases and 5.9% more cases within 20% of the actual case length compared with the schedulers and only overpredicted 5.3% more. The model assisted schedulers to predict 3.4% more cases within 20% of the actual case length and 4.3% fewer underpredicted cases. CONCLUSIONS: We created a unique framework that is being leveraged every day to predict surgical case length more accurately at case posting time and could be potentially utilized to deploy future machine learning models.

The effects of temperature and salinity on the blood chemistry and survival of juvenile Atlantic tarpon Megalops atlanticus.

Atlantic tarpon Megalops atlanticus are highly migratory sportfish that support recreational fisheries throughout their range. In US waters, juveniles can be found in coastal and estuarine habitats along the Gulf of Mexico and Atlantic seaboard, with temperature limiting their northern latitudinal distribution. Juveniles may overwinter in these areas during the first several years of life. Low temperatures are known to cause mortality in adults, but the challenges of temperature are less understood for juveniles. Furthermore, salinity, which can change dramatically in these habitats, may have a synergistic effect with temperature. To examine the physiological effects of temperature and salinity on juvenile tarpon, wild fish were acclimated to a range of conditions that potentially occur in the northern range of their estuarine habitats. The haematology of juvenile tarpon was examined in two salinity (≤2 and ≥30 ppt) and temperature (15 and 25°C) treatments, followed by a low-temperature tolerance test. After 2 weeks in treatment conditions, blood samples were analysed for haematocrit, pH, red blood cell concentration, haemoglobin content and plasma osmolality. Increased plasma osmolality was observed in fish at low temperature (15°C compared to 25°C) and at high salinity (≥30 ppt compared to ≤2 ppt). Blood pH was increased at 15°C compared to 25°C, with the highest pH at 15°C and low salinity. Haemoglobin, haematocrit and red blood cell concentration were higher at 25°C than 15°C, with haemoglobin lowest at 15°C and low salinity. For the low-temperature tolerance test, all fish were acclimated to 15°C for 2 weeks, then transferred to separate tanks where temperature was gradually decreased at 0.9 ± 0.1°C/h until fish lost equilibrium. Fish at low salinity lost equilibrium more rapidly (1 ppt, 12.65 ± 0.46°C) than fish at high salinity (30 ppt, 11.26 ± 0.14°C). The results indicate juvenile tarpon are susceptible to low temperature, which is exacerbated by low salinity, findings useful in the assessment of juvenile tarpon overwintering habitat.