Molecular tools to capture active neural circuits.

To understand how neurons and neural circuits function during behaviors, it is essential to record neuronal activity in the brain in vivo. Among the various technologies developed for recording neuronal activity, molecular tools that induce gene expression in an activity-dependent manner have attracted particular attention for their ability to clarify the causal relationships between neuronal activity and behavior. In this review, we summarize recently developed activity-dependent gene expression tools and their potential contributions to the study of neural circuits.

Distinct Indications for Adjuvant Therapy in Resected Invasive Mucinous Cystic Neoplasms of the Pancreas Compared with Pancreatic Ductal Adenocarcinoma.

BACKGROUND: Surgical and adjuvant management of mucinous cystic neoplasms (MCNs) lacks formal guidelines and data is limited to institutional studies. Factors associated with receipt of adjuvant therapy and any associated impact on survival remain to be clarified. In the absence of other data, guidelines that recommend adjuvant chemotherapy for invasive pancreatic adenocarcinoma have been extrapolated to MCN. PATIENTS AND METHODS: The National Cancer Database (2004-2019) was utilized to identify all patients that underwent pancreatic resection for invasive MCNs. Patients that received neoadjuvant therapy or did not undergo lymphadenectomy were excluded. Patient, tumor, and treatment factors associated with survival were assessed. RESULTS: For 161 patients with invasive MCN, median overall survival (OS) was 133 months and 45% of patients received adjuvant therapy. Multivariable analysis demonstrated that poorly differentiated tumors [odds ratio (OR) 4.19, 95% confidence interval (CI) 1.47-11.98; p = 0.008] and positive lymph node status (OR 2.67, 95% CI 1.02-6.98; p = 0.042) were independent predictors of receiving adjuvant therapy. Lymph node positivity [hazard ratio (HR) 2.90, 95% CI 1.47-5.73; p = 0.002], positive margins (HR 5.28, 95% CI 2.28-12.27; p < 0.001), and stage III disease (HR 12.46, 95% CI 1.40-111.05; p = 0.024) were associated with worse OS. Receipt of adjuvant systemic therapy was independently associated with decreased risk of mortality in node positive patients (HR 0.23, 95% CI 0.10-0.69; p = 0.002). Survival was not associated with adjuvant therapy in patients with negative lymph nodes or margin negative status. CONCLUSION: In contrast to pancreatic ductal adenocarcinoma (PDAC), where adjuvant therapy improves OS for every tumor stage, surgery alone for invasive MCN is not associated with improved OS compared with surgery plus adjuvant therapy in node-negative patients. Surgery alone is likely sufficient for a subset of invasive MCN.

Long-Duration Neoadjuvant Therapy with FOLFIRINOX Yields Favorable Outcomes for Patients Who Undergo Surgery for Pancreatic Cancer.

BACKGROUND: In 2023 alone, it's estimated that over 64,000 patients will be diagnosed with PDAC and more than 50,000 patients will die of the disease. Current guidelines recommend neoadjuvant therapy for patients with borderline resectable and locally advanced PDAC, and data is emerging on its role in resectable disease. Neoadjuvant chemotherapy may increase the number of patients able to receive complete chemotherapy regimens, increase the rate of microscopically tumor-free resection (R0) margin, and aide in identifying unfavorable tumor biology. To date, this is the largest study to examine surgical outcomes after long-duration neoadjuvant chemotherapy for PDAC. METHODS: Retrospective analysis of single-institution data. RESULTS: The routine use of long-duration therapy in our study (median cycles: FOLFIRINOX = 10; gemcitabine-based = 7) is unique. The majority (85%) of patients received FOLFIRINOX without radiation therapy; the R0 resection rate was 76%. Median OS was 41 months and did not differ significantly among patients with resectable, borderline-resectable, or locally advanced disease. CONCLUSIONS: This study demonstrates that in patients who undergo surgical resection after receipt of long-duration neoadjuvant FOLFIRINOX therapy alone, survival outcomes are similar regardless of pretreatment resectability status and that favorable surgical outcomes can be attained.

Long-Term Survival Outcomes After Minimally Invasive Surgery for Ileal Neuroendocrine Tumors.

BACKGROUND: Ileal neuroendocrine tumors (i-NETs) are characterized by their multifocality and bulky mesenteric mass. Having shown that minimally invasive surgery (MIS) utilizing a hand-access port device has favorable short-term outcomes and achieves the goals of surgery for i-NETs, we sought to analyze long-term survival outcomes of MIS. METHODS: One hundred and sixty-eight patients who underwent resection of primary i-NETs at a single institution between January 2007 and February 2023 were retrospectively studied. Patients were categorized into the MIS or open surgery cohorts on an intention-to-treat basis. Open surgery was selected mainly based on the need for hepatectomy or bulky mesenteric mass resection. Overall survival was analyzed using log-rank tests with propensity score matching (PSM) and Cox proportional hazards regression. PSM was performed to reduce standardized mean differences of the variables to <0.2. RESULTS: Overall, 129 (77%) patients underwent MIS and 39 (23%) underwent open surgery. Twenty-seven MIS patients were converted to an open procedure. The median follow-up time was 49 months (interquartile range 23-87 months). In the PSM cohorts, overall survival did not differ significantly between the MIS and open surgery cohorts {median 99 months (95% confidence interval [CI] 91-not applicable [NA]) vs. 103 months (95% CI 86-NA), p = 0.77; hazard ratio 0.87 (95% CI 0.33-2.2), p = 0.77}. CONCLUSIONS: MIS is an alternative to open surgery for i-NETs, achieving similar short- and long-term oncological outcomes. Bulky mesenteric mass and a plan for concurrent liver resection are potential criteria for open surgery.

Minimal Residual Disease using a Plasma-Only Circulating Tumor DNA Assay to Predict Recurrence of Metastatic Colorectal Cancer Following Curative Intent Treatment.

PURPOSE: Minimal residual disease (MRD) detection can identify the recurrence in patients with colorectal cancer (CRC) following definitive treatment. We evaluated a plasma-only MRD assay to predict recurrence and survival in patients with metastatic CRC who underwent curative intent procedures (surgery and/or radiotherapy), with or without (neo)adjuvant chemotherapy. The primary objective of this study was to assess the correlation of postprocedure tumor cell-free DNA detection status with radiographic disease recurrence. EXPERIMENTAL DESIGN: Preprocedure and postprocedure longitudinal samples were collected from 53 patients and analyzed with a multiomic MRD assay detecting circulating tumor DNA (ctDNA) from genomic and epigenomic signals. Preprocedure and postprocedure ctDNA detection correlated with recurrence-free and overall survival (OS). RESULTS: From 52 patients, 230/233 samples were successfully analyzed. At the time of data cutoff, 36 (69.2%) patients recurred with median follow-up of 31 months. Detectable ctDNA was observed in 19/42 patients (45.2%) with ctDNA analyzed 3 weeks postprocedure. ctDNA detection 3 weeks postprocedure was associated with shorter median recurrence-free survival (RFS; HR, 5.27; 95% CI, 2.31-12.0; P < 0.0001) and OS (HR, 12.83; 95% CI, 3.6-45.9; P < 0.0001). Preprocedure ctDNA detection status was not associated with RFS but was associated with improved OS (HR, 4.65; 95% CI, 1.4-15.2; P = 0.0111). Undetectable ctDNA preprocedure had notable long-term OS, >90% 3 years postprocedure. CONCLUSIONS: In this cohort of oligometastatic CRC, detection of ctDNA preprocedure or postprocedure was associated with inferior outcomes even after accounting for known prognostic clinicopathologic variables. This suggests ctDNA may enhance current risk stratification methods helping the evaluation of novel treatments and surveillance strategies toward improving patient outcomes.

Improved survival of patients receiving immunotherapy and chemotherapy following curative-intent resection of colorectal liver metastases.

BACKGROUND: Despite significant advancements in the treatment of patients with colorectal liver metastases (CRLMs), only a minority will experience long-term survival. This study aimed to determine the effect of chemotherapy (CT) and immunotherapy (IT) compared with that of CT alone on patient survival after surgical resection. METHODS: Patients undergoing curative-intent liver resection followed by adjuvant systemic therapy for stage IV colon cancer were identified using the National Cancer Database. Patients were stratified into type of therapy (CT alone vs CT + IT) and microsatellite status. Propensity score-weighted analysis was performed through 1:1 matching based on the nearest neighbor method. RESULTS: Of 9943 patients who underwent resection of CRLMs, 7971 (80%) received systemic adjuvant therapy. Of 7971 patients, 1432 (18%) received a combination of CT and IT. Microsatellite status was not associated with overall survival (OS). Adjuvant CT + IT was associated with increased 3-year OS compared with that of CT alone in both the unmatched cohort (55% vs 48%, respectively; P < .001) and matched cohort (52% vs 48%, respectively; P = .050). On multivariate analysis, older age, positive resection margins, and KRAS mutation were independent predictors of poor survival, whereas the administration of adjuvant CT + IT was an independent predictor of improved survival. CONCLUSION: IT combined with CT was associated with improved survival compared with that of CT alone after curative-intent resection of CRLMs, regardless of microsatellite instability status. Clinical trials to determine optimal patient selection, IT regimen, and long-term efficacy to improve outcomes of patients with CRLMs are warranted.

Metastatic melanoma to small bowel: metastasectomy is supported in the era of immunotherapy and checkpoint inhibitors.

BACKGROUND: Metastatic melanoma to the small bowel is an aggressive disease often accompanied by obstruction, abdominal pain, and gastrointestinal bleeding. With advancements in melanoma treatment, the role for metastasectomy continues to evolve. Inclusion of novel immunotherapeutic agents, such as checkpoint inhibitors, into standard treatment regimens presents potential survival benefits for patients receiving metastasectomy. CASE PRESENTATION: We report an institutional experience of 15 patients (12 male, 3 female) between 2014-2022 that underwent small bowel metastasectomy for metastatic melanoma and received perioperative systemic treatment. Median age of patients was 64 years (range: 35-83 years). No patients died within 30 days of their surgery, and the median hospital length of stay was 5 days. Median overall survival in these patients was 30.1 months (range: 2-115 months). Five patients died from disease (67 days, 252 days, 426 days, 572 days, 692 days postoperatively), one patient died of non-disease related causes (1312 days postoperatively), six patients are alive with disease, and three remain disease free. CONCLUSIONS: This case series presents an updated perspective of the utility of metastasectomy for small bowel metastasis in the age of novel immunotherapeutic agents as standard systemic treatment. Small bowel metastasectomy for advanced melanoma performed in conjunction with perioperative systemic therapy is safe and appears to promote long-term survival and enhanced quality of life.

RIM-BP2 regulates Ca2+ channel abundance and neurotransmitter release at hippocampal mossy fiber terminals.

Synaptic vesicles dock and fuse at the presynaptic active zone (AZ), the specialized site for transmitter release. AZ proteins play multiple roles such as recruitment of Ca2+ channels as well as synaptic vesicle docking, priming, and fusion. However, the precise role of each AZ protein type remains unknown. In order to dissect the role of RIM-BP2 at mammalian cortical synapses having low release probability, we applied direct electrophysiological recording and super-resolution imaging to hippocampal mossy fiber terminals of RIM-BP2 knockout (KO) mice. By using direct presynaptic recording, we found the reduced Ca2+ currents. The measurements of excitatory postsynaptic currents (EPSCs) and presynaptic capacitance suggested that the initial release probability was lowered because of the reduced Ca2+ influx and impaired fusion competence in RIM-BP2 KO. Nevertheless, larger Ca2+ influx restored release partially. Consistent with presynaptic recording, STED microscopy suggested less abundance of P/Q-type Ca2+ channels at AZs deficient in RIM-BP2. Our results suggest that the RIM-BP2 regulates both Ca2+ channel abundance and transmitter release at mossy fiber synapses.

A Machine Learning Approach to Predict Postoperative Pancreatic Fistula After Pancreaticoduodenectomy Using Only Preoperatively Known Data.

BACKGROUND: Clinically-relevant postoperative pancreatic fistula (CR-POPF) following pancreaticoduodenectomy (PD) is a major postoperative complication and the primary determinant of surgical outcomes. However, the majority of current risk calculators utilize intraoperative and postoperative variables, limiting their utility in the preoperative setting. Therefore, we aimed to develop a user-friendly risk calculator to predict CR-POPF following PD using state-of-the-art machine learning (ML) algorithms and only preoperatively known variables. METHODS: Adult patients undergoing elective PD for non-metastatic pancreatic cancer were identified from the ACS-NSQIP targeted pancreatectomy dataset (2014-2019). The primary endpoint was development of CR-POPF (grade B or C). Secondary endpoints included discharge to facility, 30-day mortality, and a composite of overall and significant complications. Four models (logistic regression, neural network, random forest, and XGBoost) were trained, validated and a user-friendly risk calculator was then developed. RESULTS: Of the 8666 patients who underwent elective PD, 13% (n = 1160) developed CR-POPF. XGBoost was the best performing model (AUC = 0.72), and the top five preoperative variables associated with CR-POPF were non-adenocarcinoma histology, lack of neoadjuvant chemotherapy, pancreatic duct size less than 3 mm, higher BMI, and higher preoperative serum creatinine. Model performance for 30-day mortality, discharge to a facility, and overall and significant complications ranged from AUC 0.62-0.78. CONCLUSIONS: In this study, we developed and validated an ML model using only preoperatively known variables to predict CR-POPF following PD. The risk calculator can be used in the preoperative setting to inform clinical decision-making and patient counseling.

National Practice Patterns in Malignant Peritoneal Mesothelioma: Updates in Management and Survival.

BACKGROUND: Malignant peritoneal mesothelioma (MPM) is a rare malignancy with a historically poor prognosis. Cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) has emerged as an effective therapy for patients with peritoneal malignancies. A contemporary analysis of trends in management of and survival from MPM is warranted. METHODS: Patients with MPM were identified from the National Cancer Database (2004-2018). Patients were categorized by treatment (CRS-HIPEC, CRS-chemotherapy, CRS only, chemotherapy only, no treatment), and joinpoint regression was employed to compute the annual percent change (APC) in treatment over time. Multivariable Cox proportional hazards models were used to analyze factors associated with survival. RESULTS: Of 2683 patients with MPM, 19.1% underwent CRS-HIPEC, and 21.1% received no treatment. Joinpoint regression revealed a statistically significant increase in the proportion of patients undergoing CRS-HIPEC over time (APC 3.21, p = 0.01), and a concurrent decrease in the proportion of patients who underwent no treatment (APC - 2.21, p = 0.02). Median overall survival was 19.5 months. Factors independently associated with survival included CRS-HIPEC, CRS, histology, sex, age, race, Charlson Comorbidity Index, insurance, and hospital type. Although there was a strong association between year of diagnosis and survival on univariate analysis (2016-2018 HR 0.67, p < 0.001), this association was attenuated after adjustment for treatment. CONCLUSIONS: CRS-HIPEC is increasingly employed as a treatment for MPM. In parallel, there has been a decrease in patients receiving no treatment with an increase in overall survival. These findings suggest that patients with MPM may be receiving more appropriate therapy; however, a substantial proportion of patients may remain undertreated.

Compartmentalization of soluble endocytic proteins in synaptic vesicle clusters by phase separation.

Synaptic vesicle (SV) clusters, which reportedly result from synapsin's capacity to undergo liquid-liquid phase separation (LLPS), constitute the structural basis for neurotransmission. Although these clusters contain various endocytic accessory proteins, how endocytic proteins accumulate in SV clusters remains unknown. Here, we report that endophilin A1 (EndoA1), the endocytic scaffold protein, undergoes LLPS under physiologically relevant concentrations at presynaptic terminals. On heterologous expression, EndoA1 facilitates the formation of synapsin condensates and accumulates in SV-like vesicle clusters via synapsin. Moreover, EndoA1 condensates recruit endocytic proteins such as dynamin 1, amphiphysin, and intersectin 1, none of which are recruited in vesicle clusters by synapsin. In cultured neurons, like synapsin, EndoA1 is compartmentalized in SV clusters through LLPS, exhibiting activity-dependent dispersion/reassembly cycles. Thus, beyond its essential function in SV endocytosis, EndoA1 serves an additional structural function by undergoing LLPS, thereby accumulating various endocytic proteins in dynamic SV clusters in concert with synapsin.

Metastatic colorectal adenocarcinoma tumor purity assessment from whole exome sequencing data.

Tumors rich in stroma are associated with advanced stage and poor prognosis in colorectal adenocarcinoma (CRC). Abundance of stromal cells also has implications for genomic analysis of patient tumors as it may prevent detection of somatic mutations. As part of our efforts to interrogate stroma-cancer cell interactions and to identify actionable therapeutic targets in metastatic CRC, we aimed to determine the proportion of stroma embedded in hepatic CRC metastases by performing computational tumor purity analysis based on whole exome sequencing data (WES). Unlike previous studies focusing on histopathologically prescreened samples, we used an unbiased in-house collection of tumor specimens. WES from CRC liver metastasis samples were utilized to evaluate stromal content and to assess the performance of three in silico tumor purity tools, ABSOLUTE, Sequenza and PureCN. Matching tumor derived organoids were analyzed as a high purity control as they are enriched in cancer cells. Computational purity estimates were compared to those from a histopathological assessment conducted by a board-certified pathologist. According to all computational methods, metastatic specimens had a median tumor purity of 30% whereas the organoids were enriched for cancer cells with a median purity estimate of 94%. In line with this, variant allele frequencies (VAFs) of oncogenes and tumor suppressor genes were undetectable or low in most patient tumors, but higher in matching organoid cultures. Positive correlation was observed between VAFs and in silico tumor purity estimates. Sequenza and PureCN produced concordant results whereas ABSOLUTE yielded lower purity estimates for all samples. Our data shows that unbiased sample selection combined with molecular, computational, and histopathological tumor purity assessment is critical to determine the level of stroma embedded in metastatic colorectal adenocarcinoma.

Increased vesicle fusion competence underlies long-term potentiation at hippocampal mossy fiber synapses.

Presynaptic long-term potentiation (LTP) is thought to play an important role in learning and memory. However, the underlying mechanism remains elusive because of the difficulty of direct recording during LTP. Hippocampal mossy fiber synapses exhibit pronounced LTP of transmitter release after tetanic stimulation and have been used as a model of presynaptic LTP. Here, we induced LTP by optogenetic tools and applied direct presynaptic patch-clamp recordings. The action potential waveform and evoked presynaptic Ca2+ currents remained unchanged after LTP induction. Membrane capacitance measurements suggested higher release probability of synaptic vesicles without changing the number of release-ready vesicles after LTP induction. Synaptic vesicle replenishment was also enhanced. Furthermore, stimulated emission depletion microscopy suggested an increase in the numbers of Munc13-1 and RIM1 molecules within active zones. We propose that dynamic changes in the active zone components may be relevant for the increased fusion competence and synaptic vesicle replenishment during LTP.

Hypertension Requiring Medication Use: a Silent Predictor of Poor Outcomes After Pancreaticoduodenectomy.

BACKGROUND: Although hypertension requiring medication (HTNm) is a well-known cardiovascular comorbidity, its association with postoperative outcomes is understudied. This study aimed to evaluate whether preoperative HTNm is independently associated with specific complications after pancreaticoduodenectomy. STUDY DESIGN: Adults undergoing elective pancreaticoduodenectomy were included from the 2014-2019 NSQIP-targeted pancreatectomy dataset. Multivariable regression models compared outcomes between patients with and without HTNm. Endpoints included significant complications, any complication, unplanned readmissions, length of stay (LOS), clinically relevant postoperative pancreatic fistula (CR-POPF), and cardiovascular and renal complications. A subgroup analysis excluded patients with diabetes, heart failure, chronic obstructive pulmonary disease, estimated glomerular filtration rate from serum creatinine (eGFRCr) < 60 ml/min per 1.73 m2, bleeding disorder, or steroid use. RESULTS: Among 14,806 patients, 52% had HTNm. HTNm was more common among older male patients with obesity, diabetes, congestive heart failure, chronic obstructive pulmonary disease, functional dependency, hard pancreatic glands, and cancer. After adjusting for demographics, preoperative comorbidities, and laboratory values, HTNm was independently associated with higher odds of significant complications (aOR 1.12, p = 0.020), any complication (aOR 1.11, p = 0.030), cardiovascular (aOR 1.78, p = 0.002) and renal (aOR 1.60, p = 0.020) complications, and unplanned readmissions (aOR 1.14, p = 0.040). In a subgroup analysis of patients without major preoperative comorbidity, HTNm remained associated with higher odds of significant complications (aOR 1.14, p = 0.030) and cardiovascular complications (aOR 1.76, p = 0.033). CONCLUSIONS: HTNm is independently associated with cardiovascular and renal complications after pancreaticoduodenectomy and may need to be considered in preoperative risk stratification. Future studies are necessary to explore associations among underlying hypertension, specific antihypertensive medications, and postoperative outcomes to investigate potential risk mitigation strategies.

Hand-Assisted Versus Pure Minimally-Invasive Distal Pancreatectomy: Is There a Downside to Lending a Hand?

BACKGROUND: Hand-assisted laparoscopic distal pancreatectomy (HALDP) is suggested to offer similar outcomes to pure laparoscopic distal pancreatectomy (LDP). However, given the longer midline incision, it is unclear whether HALDP increases the risk of postoperative hernia. Our aim was to determine the risk of postoperative incisional hernia development after HALDP. METHODS: We retrospectively collected data from patients undergoing HALDP or LDP at a single center (2012-2020). Primary endpoints were postoperative incisional hernia and operative time. All patients had at minimum six months of follow-up. Outcomes were compared using unadjusted and multivariable regression analyses. RESULTS: Ninety-five patients who underwent laparoscopic distal pancreatectomy were retrospectively identified. Forty-one patients (43%) underwent HALDP. Patients with HALDP were older (median, 67 vs. 61 years, p = 0.02). Sex, race, Body Mass Index (median, 27 vs. 26), receipt of neoadjuvant chemotherapy, gland texture, wound infection rates, postoperative pancreatic fistula, overall complications, and hospital length-of-stay were similar between HALDP and LDP (all p > 0.05). In unadjusted analysis, operative times were shorter for HALDP (164 vs. 276 min, p < 0.001), but after adjustment, did not differ significantly (MR 0.73; 0.49-1.07, p = 0.1). Unadjusted incidence of hernia was higher in HALDP versus LDP (60% vs. 24%, p = 0.004). After adjustment, HALDP was associated with an increased odds of developing hernia (OR 7.52; 95% CI 1.54-36.8, p = 0.014). After propensity score matching, odds of hernia development remained higher for HALDP (OR 4.62; 95% CI 1.28-16.65, p = 0.031) p = 0.03). CONCLUSIONS: Compared with LDP, HALDP was associated with increased likelihood of postoperative hernia with insufficient evidence that HALDP shortens operative times. Our results suggest that HALDP may not be equivalent to LDP.