Preoperative Frailty and Malnutrition in Surgical Oncology Patients Predicts Higher Postoperative Adverse Events and Worse Survival: Results of a Blinded, Prospective Trial

BACKGROUND

Frailty, a multidimensional state leading to reduced physiologic reserve, is associated with worse postoperative outcomes. Despite the availability of various frailty tools, surgeons often make subjective assessments of patients' ability to tolerate surgery. The Risk Analysis Index (RAI) is a validated preoperative frailty assessment tool that has not been studied in cancer patients with plans for curative-intent surgery.

METHODS

In this prospective, surgeon-blinded study, patients who had abdominal malignancy with plans for resection underwent preoperative frailty assessment with the RAI and nutrition assessment by measurement of albumin, prealbumin, and C-reactive protein (CRP). Postoperative outcomes and survival were assessed.

RESULTS

The study included 220 patients, 158 (72%) of whom were considered frail (RAI ≥21). Frail patients were more likely to be readmitted within 30 and 90 days, (16% vs. 3% [P = 0.006] and 16% vs. 5% [P = 0.025], respectively). Patients with abnormal CRP, prealbumin, and albumin experienced higher rates of unplanned intensive care unit admission (CRP [27% vs. 8%; P < 0.001], albumin [30% vs. 10%; P < 0.001], prealbumin [29% vs. 9%; P < 0.001]) and increased postoperative mortality at 90 and 180 days. Survival was similar for frail and non-frail patients. In the multivariate analysis, frailty remained an independent risk factor for readmission (hazard ratio, 5.58; 95% confidence interval, 1.39-22.15; P = 0.015). In the post hoc analysis using the pre-cancer RAI score, the postoperative outcomes did not differ between the frail and non-frail patients.

CONCLUSION

In conjunction with preoperative markers of nutrition, the RAI may be used to identify patients who may benefit from additional preoperative risk stratification and increased postoperative follow-up evaluation.

Actual 5-Year Survival After Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy for Patients with Peritoneal Carcinomatosis of Colorectal Origin

BACKGROUND

Cytoreductive surgery and heated intraperitoneal chemotherapy (CRS/HIPEC) improves survival compared with chemotherapy alone in patients with peritoneal carcinomatosis (PC) of colorectal (CRC) origin, however, long-term survival data are lacking. We report the actual survival of patients who underwent CRS/HIPEC for PC of CRC origin with a minimum potential 5-year follow-up period to identify factors that preclude long-term survival.

METHODS

We performed a retrospective analysis of a prospective database, analyzing patients undergoing CRS/HIPEC for PC of CRC origin from 2007 to 2017. Patients with aborted CRS/HIPEC, postoperative follow-up <90 days, or non-CRC histology were excluded. Overall survival (OS) and disease-free survival (DFS) were measured from date of surgery. Surviving patients with <60 months of follow-up were censored at date of last follow-up.

RESULTS

A total of 103 patients met inclusion criteria and were analyzed. CC score 0-1 was achieved in 89.3% of patients, and median peritoneal cancer index (PCI) was 9 (interquartile range [IQR] 5-17). Ninety-day mortality was 2.9%. The median follow-up of survivors was 88 months. Five-year OS was 36%, and median OS was 42.5 months. Factors independently associated with poor survival included high PCI (PCI = 14-20, hazard ratio [HR] 3.1, p = 0.007, and PCI > 20, HR 5.3, p ≤ 0.001) and incomplete CRS (CC score-2, HR 2.96, p = 0.02). Patients with low PCI (0-6) had 5-year OS 60.7%.

CONCLUSIONS

Actual 5-year OS was 36% and median OS was 42.5 months. Our study demonstrates that patients with PC from CRC origin with low PCI who undergo complete surgical resection can achieve favorable long-term survival.

Consensus criteria for chronic rhinosinusitis disease control: an international Delphi Study

BACKGROUND

Chronic rhinosinusitis (CRS) disease control is a global metric of disease status for CRS. While there is broad acceptance that it is an important treatment goal, there has been inconsistency in the criteria used to define CRS control. The objective of this study was to identify and develop consensus around essential criteria for assessment of CRS disease control.

METHODS

Modified Delphi methodology consisting of three rounds to review a list of 24 possible CRS control criteria developed by a 12-person steering committee. The core authorship of the multidisciplinary EPOS 2020 guidelines was invited to participate.

RESULTS

Thirty-two individuals accepted the invitation to participate and there was no dropout of participants throughout the entire study (3 rounds). Consensus essential criteria for assessment of CRS control were: overall symptom severity, need for CRS-related systemic corticosteroids in the prior 6 months, severity of nasal obstruction, and patient-reported CRS control. Near-consensus items were: nasal endoscopy findings, severity of smell loss, overall quality of life, impairment of normal activities and severity of nasal discharge. Participants’ comments provided insights into caveats of, and disagreements related to, near-consensus items.

CONCLUSIONS

Overall symptom severity, use of CRS-related systemic corticosteroids, severity of nasal obstruction, and patient-reported CRS control are widely agreed upon essential criteria for assessment of CRS disease control. Consideration of near-consensus items to assess CRS control should be implemented with their intrinsic caveats in mind. These identified consensus CRS control criteria, together with evidence-based support, will provide a foundation upon which CRS control criteria with wide-spread acceptance can be developed.

Cytoreductive surgery with hyperthermic intraperitoneal chemotherapy: Effects of postoperative fluids beyond the first 24 h

BACKGROUND AND OBJECTIVES

There are no guidelines for intravenous fluid (IVF) administration after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC). This study assessed rates of post-CRS/HIPEC morbidity according to perioperative IVF administration.

METHODS

All patients undergoing CRS/HIPEC March 2007 to June 2018 were reviewed, recording clinicopathologic, operative, and postoperative variables. Patients were divided by peritoneal cancer index (PCI), comparing IVF volumes and types administered intraoperatively and during the first 72 h postoperatively. Optimal IVF rate cutoffs calculated using area under the receiver operating characteristic curves and Youden's index determined associations with complications.

RESULTS

Overall, 185 patients underwent CRS/HIPEC, and 81 (51%) had low PCI (<10) and 77 (49%) had high PCI (≥10). In low-PCI patients, high IVF rates on postoperative days (POD) #0-2 were associated with higher overall complications: POD#0 (46% vs. 89%, p = 0.001), POD#1 (40% vs. 86%, p < 0.05), and POD#2 (42% vs. 72%, p < 0.05). High IVF rates were associated with respiratory distress (7% vs. 26%, p = 0.02) on POD#0, ileus (14% vs. 47%, p = 0.007) and intensive care unit stay (11% vs. 33%, p = 0.022) on POD#1, and ICU stay (8% vs. 33%, p = 0.003) on POD#2.

CONCLUSIONS

For low PCI patients undergoing CRS/HIPEC, higher IVF rates were associated with postoperative complications. Post-CRS/HIPEC, IVF rates should be limited to prevent morbidity.

Surgical management of pancreatic ductal adenocarcinoma: a narrative review

Background and Objective

Pancreatic ductal adenocarcinoma (PDAC) is the third-leading cause of cancer-related death in the United States and is projected to become the second-leading cause of cancer-related death by 2030. Despite advances in systemic and radiation therapy, for patients with surgically resectable PDAC, complete surgical resection is the only potentially curative treatment option. The conduct of a safe, technically excellent pancreatectomy is essential to achieve optimal perioperative outcomes and long-term survival. In this narrative review, evidence from large, well-executed studies and clinical trials examining the technical aspects of pancreatectomy is reviewed.

Methods

A search was conducted in PubMed, Medline, and Cochrane Review databases to identify English-language randomized clinical trials, meta-analyses, and systematic reviews assessing surgical aspects of pancreatectomy for PDAC published between 2010 to 2023.

Key Content and Findings

We identified retrospective and prospective studies evaluating the technical aspects of surgery for PDAC. In this review, we evaluate data on surgical techniques of pancreatectomy for PDAC, including the role of minimally invasive techniques, extent of lymphadenectomy, reconstruction options after pancreatoduodenectomy, and the role of surgical drainage.

Conclusions

Surgical resection has a critical role in the treatment of operable PDAC. While pancreatic cancer surgery is an active area of research, conducting a technically excellent surgical resection maintains paramount importance for both oncological and perioperative outcomes. In this review, we summarize the latest evidence on surgical technique for operable PDAC.

Major Postoperative Complications Limit Adjuvant Therapy Administration in Patients Undergoing Pancreatoduodenectomy for Distal Cholangiocarcinoma or Pancreatic Ductal Adenocarcinoma

INTRODUCTION

Guidelines for perioperative systemic therapy administration in patients undergoing pancreatoduodenectomy for pancreatic adenocarcinoma (PDAC) and distal cholangiocarcinoma (dCCA) are evolving. Decisions regarding adjuvant therapy are influenced by postoperative morbidity, which is common after pancreatoduodenectomy. We evaluated whether postoperative complications are associated with receipt of adjuvant therapy after pancreatoduodenectomy.

METHODS

A retrospective analysis of patients undergoing pancreatoduodenectomy for PDAC or dCCA from 2015 to 2020 was conducted. Demographic, clinicopathologic, and postoperative variables were analyzed.

RESULTS

Overall, 186 patients were included-145 with PDAC and 41 with dCCA. Postoperative complication rates were similar for both pathologies (61% and 66% for PDAC and dCCA, respectively). Major postoperative complications (MPCs), defined as Clavien-Dindo >3, occurred in 15% and 24% of PDAC and dCCA patients, respectively. Patients with MPCs received lower rates of adjuvant therapy administration, irrespective of primary tumor (PDAC: 21 vs. 72%, p = 0.008; dCCA: 20 vs. 58%, p = 0.065). Recurrence-free survival (RFS) was worse for patients with PDAC who experienced an MPC [8 months (interquartile range [IQR] 1-15) vs. 23 months (IQR 19-27), p < 0.001] or who did not receive any perioperative systemic therapy [11 months (IQR 7-15) vs. 23 months (IQR 18-29), p = 0.038]. In patients with dCCA, 1-year RFS was worse for patients who did not receive adjuvant therapy (55 vs. 77%, p = 0.038).

CONCLUSION

Patients who underwent pancreatoduodenectomy for either PDAC or dCCA and who experienced an MPC had lower rates of adjuvant therapy and worse RFS, suggesting that clinicians adopt a standard neoadjuvant systemic therapy strategy in patients with PDAC. Our results propose a paradigm shift towards preoperative systemic therapy in patients with dCCA.

Perineural Invasion of Pancreatic Ductal Adenocarcinoma is Associated with Early Recurrence after Neoadjuvant Therapy Followed by Resection

BACKGROUND

Neoadjuvant therapy (NAT) is increasingly utilized in the treatment of pancreatic ductal adenocarcinoma (PDAC). However, there are limited data on risk factors and patterns of recurrence after surgical resection. This study aimed to analyze timing and recurrence patterns of PDAC after NAT followed by curative resection.

METHODS

The medical charts of patients with PDAC treated with NAT followed by curative-intent surgical resection at a single health system from January 1, 2012 to January 1, 2020 were retrospectively reviewed. Early recurrence was defined as recurrence within 12 months of surgical resection.

RESULTS

91 patients were included and median follow up was 20.1 months. Recurrence occurred in 50 (55%) patients, with median recurrence free survival (RFS) of 11.9 months. Overall, 18 (36%) patients had local and 32 (64%) had distant recurrences. Median RFS and overall survival (OS) between local and distant recurrence were similar. Perineural invasion (PNI) and the presence of a T2 + tumor was significantly higher in recurrence group than in no recurrence group. PNI was a significant risk factor for early recurrence.

CONCLUSION

After NAT and surgical resection of PDAC, disease recurrence was common, with distant metastasis being the most common. PNI was significantly higher in the recurrence group.

T1 Gastric Cancer is Associated With a High Incidence of Regional Lymph Node Metastases

INTRODUCTION

Early stage gastric cancer, particularly T1 disease, is associated with high recurrence-free and overall survival rates following resection with curative intent. However, rare cases of T1 gastric cancer have nodal metastasis and this is associated with poor outcomes.

METHODS

Data from gastric cancer patients treated with surgical resection and D2 lymph node (LN) dissection at a single tertiary care institution from 2010 to 2020 were analyzed. Patients with early stage (T1) tumors were assessed in detail to identify variables associated with regional LN metastasis including histologic differentiation, signet ring cells, demographics, smoking history, neoadjuvant therapy, and clinical staging by endoscopic ultrasound (EUS). We used standard statistical techniques including Mann-Whitney U and Chi-squared tests.

RESULTS

Of 426 patients undergoing surgery for gastric cancer, 34% (n = 146) were diagnosed with T1 disease on surgical pathology. Among 146 T1 (T1a, T1b) gastric cancers, 24 patients [(17%) T1a (n = 4), T1b (n = 20)] had histologically confirmed regional LN metastases. The age at diagnosis ranged between 19 and 91 y and 54.8% were male. Prior smoking status was not associated with nodal positivity (P = 0.650). Of the 24 patients with positive LN on final pathology, seven patients received neoadjuvant chemotherapy. EUS was performed on 98 (67%) of the 146 T1 patients. Of these patients, 12 (13.2%) had positive LN on final pathology; however, none (0/12) were detected on preoperative EUS. There was no association between node status on EUS and node status on final pathology (P = 0.113). The sensitivity of EUS for N status was 0%, specificity was 84.4%, negative predictive value was 82.2% and positive predictive value was 0%. Signet ring cells were identified in 42% of node negative T1 tumors and 64% of node positive T1 tumors (P = 0.063). For LN positive cases on surgical pathology, 37.5% had poor differentiation, 42% had lymphovascular invasion, and regional nodal metastases were associated with increasing T stage (P = 0.003).

CONCLUSIONS

T1 gastric cancer is associated with a substantial risk (17%) of regional LN metastasis, when pathologically staged following surgical resection and D2 lymphadenectomy. Clinically staged N+ disease by EUS was not significantly associated with pathologically staged N+ disease in these patients.

A pilot study of gut microbiome modulation to enable efficacy of neoadjuvant checkpoint-based immunotherapy (IO) following chemotherapy in pancreatic ductal adenocarcinoma (PDAC)

TPS759

Background: Neoadjuvant therapy is now a standard strategy for localized PDAC, and this preoperative window provides an excellent opportunity in which to test novel therapeutic approaches. Trials using IO in PDAC have largely been unsuccessful, and immune tolerance is implicated as a major mechanism of IO resistance. The gut and tumor microbiome have emerged as key modulators of response to both IO and chemotherapy. High tumor microbial diversity has been linked to longer survival in PDAC, and gut microbiota may have the ability to colonize pancreatic tumors. There is preclinical evidence that endogenous microbiota promotes the immunosuppressive tumor microenvironment characteristic of PDAC through stimulation of pro-tumor regulatory T cells and myeloid-derived suppressor cells at the expense of anti-tumor activated CD4+ and CD8+ T cells. Further, preclinical data show that ablation of the gut microbiota may induce T cell activation, improve immune surveillance, and increase sensitivity to IO. We hypothesize that ablative antibiotics (abx) will activate tumor infiltrating T cells and enhance IO activity in PDAC. Methods: This is a multi-center, single-arm, open-label pilot study of pre-operative chemotherapy followed by abx and pembrolizumab to evaluate overall immune response to abx + IO. Eligible patients will have histologically confirmed, resectable PDAC, without probiotic consumption or use of immunosuppressive agents. Patients will be enrolled at diagnosis after undergoing a baseline biopsy. They will then receive mFOLFIRINOX every 2 weeks for 5 cycles. After completion of chemotherapy, ciprofloxacin 500 mg PO BID and metronidazole 500 mg PO TID will be administered for 21 days, and pembrolizumab 200 mg IV x1 will be given 7 days after initiation of abx. Patients will then undergo surgical resection and adjuvant therapy at the investigators’ discretion. On-treatment biopsy will be obtained prior to cycle 5 of mFOLFIRINOX. Blood and stool will be collected at baseline, during mFOLFIRINOX therapy, before and after pembrolizumab administration, and postoperatively. The primary endpoint is the overall immune response, which will be measured as activation of one or more of the T cell markers HLA-DR, CD38, CD25, Ki67, and CD69, defined as an increase in expression level of at least 20% from the on-treatment specimen to the surgical specimen, before and after abx + IO. Key secondary endpoints will be the evaluation of adverse events, R0 resection rate, histologic regression score, objective response rate, and overall survival rate. Correlative studies will be carried out to evaluate immune and microbiome changes in the blood and tissue following abx and pembrolizumab. These findings will be correlated with clinical endpoints. The target study accrual is 25 patients. Clinical trial information: NCT05462496 .

Preoperative frailty to predict short-term outcomes in patients with cancer

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Background: Frailty is associated with increased postoperative complications. Despite multiple evidence-based modalities to assess frailty, surgeons often make subjective assessments of patients’ ability to tolerate surgery. Identification of those at risk of poor outcomes is particularly important in Surgical Oncology, as major resections may worsen debility and functional status, limiting the patients' ability to receive further therapy. The Risk Analysis Index (RAI-C) is a validated tool to assess frailty in surgical patients. It assigns points for any cancer diagnosis, potentially overestimating frailty in Surgical Oncology patients, and has not been validated in this subgroup. Methods: We performed a prospective, surgeon-blinded study to correlate results of a preoperatively administered frailty survey to predict short- and long-term outcomes in patients with histologically proven malignancy who underwent surgery. The RAI-C, Patient Health Questionnaire (PHQ9), and General Anxiety Disorder (GAD) surveys were administered to assess for frailty, depression, and anxiety, respectively; C-reactive protein (CRP), pre-albumin, albumin, and hematocrit were obtained. Outcomes, including readmission, major complications, ICU admission, disposition (home vs rehabilitation/nursing facility), and 1-year survival were compared between the different groups as defined by survey and lab results. Results: One hundred ninety-one patients were included, of which 135 patients were considered frail based on the predefined value (RAI-C ≥21). Frail patients were more likely to be readmitted within 30 days (14% vs 2%, P=0.01). No difference was found in length of stay, 90-day readmission, ICU admission, major complications, or disposition. Only 15.8% of patients met criteria for anxiety and 11% met criteria for depression. Measured outcomes were similar in patients defined as anxious or depressed. Patients with abnormal pre-albumin levels were more likely to require ICU admissions (31% vs 8%, P <0.005), postoperative intubation (12% vs 0.02%, P=0.02), and to be discharged to a facility other than home (19% vs 10%, P=0.01). Similar trends were noted for patients with abnormal albumin levels who also had longer lengths of stay (mean 9.32 vs 7.88 days, P=0.007). There was an association of improved 1-year survival in patients with normal CRP, pre-albumin, albumin, and hematocrit levels. Frailty as determined by RAI-C survey was not associated with decreased 1-year survival. Conclusions: The RAI-C is a validated tool that can be used for prescreening of Surgical Oncology patients at risk of postoperative readmission, however the score did not correlate with other important outcomes including major morbidity, discharge disposition, and 1-year survival. Results from the survey, as well as preoperative laboratory results can be used in screening patients who may benefit from preoperative optimization and increased follow-up.

The EUFOREA pocket guide for chronic rhinosinusitis

Chronic rhinosinusitis (CRS) is known to affect around 5 % of the total population, with major impact on the quality of life of those severely affected (1). Despite a substantial burden on individuals, society and health economies, CRS often remains underdiagnosed, under-estimated and under-treated (2). International guidelines like the European Position Paper on Rhinosinusitis and Nasal Polyps (EPOS) (3) and the International Consensus statement on Allergy and Rhinology: Rhinosinusitis 2021 (ICAR) (4) offer physicians insight into the recommended treatment options for CRS, with an overview of effective strategies and guidance of diagnosis and care throughout the disease journey of CRS.

Gallbladder Cancer: A Single-Institution 10-Year Experience-Analysis of Adenocarcinoma Subtypes and Tumors Arising from Intracholecystic Papillary Neoplasms

BACKGROUND

Gallbladder cancer accounts for 1.2% of global cancer diagnoses. Literature on biliary-type adenocarcinoma (BTA), and specifically carcinoma arising from intracholecystic papillary-tubular neoplasms (ICPNs), is limited. This study describes a retrospective, single-institution experience with gallbladder cancer, focusing on histological subtypes and prognosis.

METHODS

A retrospective review was performed of patients who underwent cholecystectomy for a malignant neoplasm of the gallbladder between 2007 and 2017. Demographic, clinicopathologic, and operative variables, as well as survival outcomes, were analyzed.

RESULTS

From a total of 145 patients, BTAs were most common (93, 64%). Compared with non-BTAs, BTAs were diagnosed at a lower American Joint Committee on Cancer stage (p = 0.045) and demonstrated longer median recurrence-free survival (38 vs. 16 months, p = 0.014; median follow-up 36 months). Tumors arising from ICPNs (18, 12%) were more commonly associated with BTA (14 cases). Compared with BTAs not associated with ICPNs (29 patients), associated cases demonstrated lower pathologic stage (p = 0.006) and lower rates of liver and perineural invasion (0% vs. 49% and 14% vs. 48%, respectively; p < 0.05). Cumulative 5-year survival probability was higher for patients with gallbladder neoplasm of any subtype associated with ICPNs compared with those that were not associated with ICPNs (54% vs. 41%, p = 0.019; median follow-up 23 months). This difference was also significant when comparing BTAs associated with ICPNs and non-associated cases (63% vs. 52%, p = 0.005).

CONCLUSIONS

This study demonstrated unique pathological and prognostic features of BTAs and of carcinomas arising from ICPNs. Histopathological variance may implicate prognosis and may be used to better guide clinical decision making in the treatment of these patients.

Induction FOLFIRINOX for patients with locally unresectable pancreatic ductal adenocarcinoma

OBJECTIVES

Patients with locally advanced pancreatic adenocarcinoma (PDAC) receive induction chemotherapy with or without radiation, with the goal of R0 resection and improving survival. Herein, we evaluate the outcomes of patients who presented with Stage III PDAC and received induction FOLFIRINOX.

METHODS

An institutional database was queried for consecutive patients who received induction FOLFIRINOX for locally unresectable PDAC between 2010 and 2016. Clinical and radiographic parameters were assessed pre- and posttreatment, and clinical outcomes were evaluated.

RESULTS

There were 200 patients who met the inclusion criteria. The median number of cycles of FOLFIRINOX was 8, 70% (n = 140) received radiation, and 18% (n = 36) underwent resection. Median overall survival (OS) in resected patients was 36 months (95% confidence interval [CI]: 24-56), and this group had improved OS compared to patients that did not undergo resection (hazard ratio (95% CI): 0.41 (0.26-0.64), p < 0.001). Patients (n = 112) who did not progress on induction therapy but remained unresectable had a median OS of 23.9 months (95% CI: 21.1-25.4).

CONCLUSION

Nearly 20% of patients with locally advanced PDAC responded sufficiently to induction FOLFIRINOX to undergo resection, which was associated with improved OS compared to patients that did not undergo resection. Patients with stable disease who remain unresectable represent a group of patients with locally advanced PDAC who may benefit from optimization of additional nonoperative treatment.

Laparoscopic cytoreductive surgery and hyperthermic intraperitoneal chemotherapy is associated with improved perioperative outcomes: a single-center early experience propensity-matched analysis

INTRODUCTION

The role of laparoscopy in cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) is not well established. Herein, we describe our early experience of laparoscopic CRS/HIPEC in patients with low-volume peritoneal disease compared to patients who underwent open CRS/HIPEC during the same time period.

METHODS

Using a prospectively maintained database, patients who underwent laparoscopic CRS/HIPEC were compared to a control cohort of patients who underwent open CRS/HIPEC, matched for peritoneal carcinomatosis index (PCI), completeness of cytoreduction, and tumor histology.

RESULTS

Between 2008 and 2017, 16 patients underwent laparoscopic CRS/HIPEC and were compared to a matched control cohort of 32 patients who underwent open CRS/HIPEC. Clinical and demographic data were similar between the groups. PCI, number of resected organs, and optimal cytoreduction rates were comparable. Patients who underwent laparoscopic experienced a lower estimated blood loss, (median, [IQR 1-3]); 150 mL, [50-300] vs. 100 mL, [50-125], p = 0.04, shorter length of stay (median [IQR 1-3]; 4 days [3-6] vs. 6 days [5-8], p < 0.01, and a lower 30-day complication rate (6.3% vs. 56.3%, p < 0.01). There was no difference in progression-free survival (p = 0.577) and overall survival (p = 0.472) between the groups.

CONCLUSIONS

This preliminary study demonstrates that laparoscopic CRS/HIPEC is feasible and safe for curative treatment in selected patients with low tumor volume. Minimally invasive CRS/HIPEC is associated with fewer postoperative complications and shorter length of stay. There was no difference in long-term oncological outcomes between the groups.

Adjuvant Chemotherapy Is Not Guided by Pathologic Treatment Effect After Neoadjuvant Chemotherapy in Pancreatic Cancer

OBJECTIVES

Currently, there is no guidance for optimal adjuvant chemotherapy selection after pancreatectomy with a partial or poor response to neoadjuvant therapy. This study seeks to describe an institution's practice patterns of adjuvant chemotherapy selection after neoadjuvant therapy.

METHODS

Patients at a single institution receiving neoadjuvant chemotherapy followed by pancreatectomy for pancreatic cancer were reviewed. Patients enrolled in trials or without follow-up were excluded. Types of chemotherapy, the College of American Pathologists pathologic tumor response, and medical oncology plans were recorded.

RESULTS

Forty-one patients met inclusion criteria. Pathologic review of treatment effect demonstrated that 3 patients (7.3%) had complete pathologic response, 3 (7.3%) had near complete pathologic response, 16 (39%) had partial response, and 14 (34.1%) had poor/no response to neoadjuvant chemotherapy. Fourteen of the 30 patients with partial or poor response (46.7%) received an alternate adjuvant regimen. Pathologic response to neoadjuvant chemotherapy specifically guided therapy in 11 (30.5%) patients.

CONCLUSIONS

Despite 73.1% of patients with partial or poor response to neoadjuvant chemotherapy, only 46.7% received a different adjuvant regimen. Medical oncologists infrequently considered treatment effect when choosing adjuvant therapy. Pathologic response to neoadjuvant chemotherapy should be considered when selecting adjuvant chemotherapy.

Hepatitis C-positive Black patients develop hepatocellular carcinoma at earlier stages of liver disease and present with a more aggressive phenotype

BACKGROUND

In the United States, mortality after a diagnosis of hepatocellular carcinoma (HCC) is higher in patients who are Black than in patients of other racial groups. The objective of this study was to clarify factors contributing to this disparity by analyzing liver and tumor characteristics in patients with HCC who have a history of hepatitis C virus (HCV) infection.

METHODS

Records of patients with HCV and HCC at the authors' institution from 2003 to 2018 were retrospectively reviewed. Race and ethnicity were self-identified. Imaging, laboratory, and pathologic features were compared between Black and non-Black cohorts.

RESULTS

Among 1195 individuals with HCC, 390 identified as Black. At the time of HCC diagnosis, Black patients had better liver function, as measured by Child-Pugh score, Model of End-Stage Liver Disease score, histology of nontumor tissue, and fibrosis-4 (FIB-4) score (all P < .05). FIB-4 scores were <3.25 in 31% of Black patients. In addition, Black patients had less early stage HCC (20.2% vs 32.3%; P < .05), larger tumors (median [interquartile range]: 3.5 cm [2.2-6.2 cm] vs 3.1 cm [2.1-5.1 cm]; P < .01), more multiple tumors (median, [interquartile range]: 1 tumor [1-3 tumors] vs 1 tumor [1-2 tumors]; P = .03), more poorly differentiated tumors (30.3% vs 20.5%; P < .05), and more microvascular invasion (67.2% vs 56.5%; P < .05).

CONCLUSIONS

Black patients with HCV exposure develop HCC at earlier stages of liver disease than members of other racial groups. Nearly one-third would not qualify for HCC screening using the common FIB-4 cirrhosis threshold. Practice guidelines that stress HCC surveillance for cirrhotic patients with HCV may need to be revised to be more inclusive for Black patients. In addition, tumors in Black patients carry worse prognostic features, and molecular studies are needed to characterize their biologic properties.

Csf1r or Mer inhibition delays liver regeneration via suppression of Kupffer cells

INTRODUCTION

Murine Kupffer cells (KCs) comprise CD11bhi and F4/80hi subsets. Tissue-resident macrophages are known to express the tyrosine kinase receptors colony-stimulating factor 1 receptor (Csf1r) and Mer. However, the expression of Csf1r and Mer on KC subsets and the importance of these tyrosine kinases during liver regeneration (LR) are unknown.

METHODS

KCs from wild-type and Csf1r-GFP mice were characterized by flow cytometry. Partial hepatectomy (PH) was performed in mice treated with clodronate liposomes, a Csf1r small molecule inhibitor or depleting antibody, or a small molecule Mer inhibitor. Sera and livers were analyzed. The function of sorted KC subsets was tested in vitro.

RESULTS

Mer was specifically expressed on tissue-resident F4/80hi KCs, 55% of which also expressed Csf1r. Mer+Csf1r+ and Mer+Csf1r- KCs had distinct expression of macrophage markers. Csf1r inhibition in mice reduced F4/80hi KCs by approximately 50%, but did not affect CD11bhi KCs. Clodronate liposomes depleted F4/80hi KCs, but also altered levels of other intrahepatic leukocytes. Csf1r inhibition delayed LR, as demonstrated by a 20% reduction in liver-to-body weight ratios 7 days after PH. At 36h after PH, Csf1r inhibition increased serum ALT and histological liver injury, and decreased liver cell proliferation. A small molecule inhibitor of Mer did not alter the percentage of KCs or their proliferation and just modestly delayed LR. In vitro, Csf1r or Mer inhibition did not decrease KC viability, but did attenuate their cytokine response to stimulation.

CONCLUSIONS

F4/80hi KCs are Mer+ and can be subdivided based on Csf1r expression. Csf1r or Mer inhibition each reduces KC cytokine production and delays LR.

Checkpoint blockade in esophagogastric cancer

There are few effective treatment options for metastatic esophagogastric adenocarcinomas after progression on second-line chemotherapy. Immune checkpoint blockade therapy is a promising treatment strategy for selected advanced esophagogastric cancer, and the PD-1 inhibitor pembrolizumab has recently been approved for metastatic or recurrent gastric or gastroesophageal junction cancer that has progressed beyond second-line systemic therapy. We review the current data supporting immune checkpoint blockade therapy in advanced esophagogastric adenocarcinoma.

Wnt/β-catenin Signaling Contributes to Tumor Malignancy and Is Targetable in Gastrointestinal Stromal Tumor

Gastrointestinal stromal tumor (GIST) is the most common type of sarcoma and usually harbors either a KIT or PDGFRA mutation. However, the molecular basis for tumor malignancy is not well defined. Although the Wnt/β-catenin signaling pathway is important in a variety of cancers, its role in GIST is uncertain. Through analysis of nearly 150 human GIST specimens, we found that some human GISTs expressed β-catenin and contained active, dephosphorylated nuclear β-catenin. Furthermore, advanced human GISTs expressed reduced levels of the Wnt antagonist DKK4. Accordingly, in human GIST T1 cells, Wnt stimulation increased β-catenin-mediated transcriptional activity in a reporter assay as well as transcription of the downstream target genes Axin2 and CCND1 In contrast, DKK4 overexpression in GIST T1 cells reduced Wnt/β-catenin signaling. In addition, we showed that nuclear β-catenin stability was partially regulated by the E3 ligase COP1, as demonstrated with coimmunoprecipitation and COP1 knockdown. Three molecular inhibitors of the Wnt/β-catenin pathway demonstrated antitumor efficacy in various GIST models, both in vitro and in vivo Notably, the tankyrase inhibitor G007-LK alone had substantial activity against tumors of genetically engineered Kit^V558Δ/+ mice, and the effect was increased by the addition of the Kit inhibitor imatinib mesylate. Collectively, our findings demonstrate that Wnt/β-catenin signaling is a novel therapeutic target for selected untreated or imatinib-resistant GISTs. Mol Cancer Ther; 16(9); 1954-66. ©2017 AACR.

Genome and transcriptome profiling of fibrolamellar hepatocellular carcinoma demonstrates p53 and IGF2BP1 dysregulation

Fibrolamellar hepatocellular carcinoma (FL-HCC) is a rare variant of HCC that most frequently affects young adults. Because of its rarity and an absence of preclinical models, our understanding of FL-HCC is limited. Our objective was to analyze chromosomal alterations and dysregulated gene expression in tumor specimens collected at a single center during two decades of experience with FL-HCC. We analyzed 38 specimens from 26 patients by array comparative genomic hybridiziation (aCGH) and 35 specimens from 15 patients by transcriptome sequencing (RNA-seq). All tumor specimens exhibited genomic instability, with a higher frequency of genomic amplifications or deletions in metastatic tumors. The regions encoding 71 microRNAs (miRs) were deleted in at least 25% of tumor specimens. Five of these recurrently deleted miRs targeted the insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1) gene product, and a correlating 100-fold upregulation of IGF2BP1 mRNA was seen in tumor specimens. Transcriptome analysis demonstrated intrapatient tumor similarity, independent of recurrence site or time. The p53 tumor suppressor pathway was downregulated as demonstrated by both aCGH and RNA-seq analysis. Notch, EGFR, NRAS, and RB1 pathways were also significantly dysregulated in tumors compared with normal liver tissue. The findings illuminate the genomic and transcriptomic landscape of this rare disease and provide insight into dysregulated oncogenic pathways and potential therapeutic targets in FL-HCC.

PD-1/PD-L1 Blockade Enhances T-cell Activity and Antitumor Efficacy of Imatinib in Gastrointestinal Stromal Tumors

PURPOSE

Tyrosine kinase inhibitors are effective in gastrointestinal stromal tumors (GISTs) but often are of transient benefit as resistance commonly develops. Immunotherapy, particularly blockade of the inhibitory receptor programmed death 1 (PD-1) or the ligand programmed death ligand 1 (PD-L1), has shown effectiveness in a variety of cancers. The functional effects of PD-1/PD-L1 blockade are unknown in GISTs.

EXPERIMENTAL DESIGN

We analyzed tumor and matched blood samples from 85 patients with GISTs and determined the expression of immune checkpoint molecules using flow cytometry. We investigated the combination of imatinib with PD-1/PD-L1 blockade in Kit^V558Δ/+ mice that develop GISTs.

RESULTS

The inhibitory receptors PD-1, lymphocyte activation gene 3, and T-cell immunoglobulin mucin-3 were upregulated on tumor-infiltrating T cells compared with T cells from matched blood. PD-1 expression on T cells was highest in imatinib-treated human GISTs. Meanwhile, intratumoral PD-L1 expression was variable. In human GIST cell lines, treatment with imatinib abrogated the IFNγ-induced upregulation of PD-L1 via STAT1 inhibition. In Kit^V558Δ/+ mice, imatinib downregulated IFNγ-related genes and reduced PD-L1 expression on tumor cells. PD-1 and PD-L1 blockade in vivo each had no efficacy alone but enhanced the antitumor effects of imatinib by increasing T-cell effector function in the presence of KIT and IDO inhibition.

CONCLUSIONS

PD-1/PD-L1 blockade is a promising strategy to improve the effects of targeted therapy in GISTs. Collectively, our results provide the rationale to combine these agents in human GISTs. Clin Cancer Res; 23(2); 454-65. ©2016 AACR.

Low protein and high-energy diet: a possible natural cause of fatty liver hemorrhagic syndrome in caged White Leghorn laying hens

Fatty liver hemorrhagic syndrome (FLHS) is a metabolic condition of chicken and other birds caused by diverse nutritional, hormonal, environmental, and metabolic factors. Here we studied the effect of different diet composition on the induction of FLHS in single comb White Leghorn (WL) Hy-line laying hens. Seventy six (76) young WL (26 wks old) laying hens and 69 old hens (84 wks old) of the same breed were each divided into 4 treatment groups and provided 4 different diet treatments. The diet treatments included: control (C), 17.5% CP, 3.5% fat (F); normal protein, high fat (HF), 17.5% CP, 7% F; low protein, normal fat (LP), 13% CP, 3.5% F; and low protein, high fat (LPHF), 13% CP, 6.5% F. The diets containing high fat also had a higher ME of 3,000 kcal/kg of feed while the other 2 diets with normal fat had a regular lower amount of ME (2750 kcal/kg). Hen-day egg production (HDEP), ADFI, BW, egg weight, plasma enzymes indicating liver damage (alkaline phosphatase [ALP], aspartate aminotransferase [AST], gamma-glutamyl transferase [GGT]), liver and abdominal fat weight, liver color score (LCS), liver hemorrhagic score (LHS), liver fat content (LFC), liver histological examination, lipid peroxidation product in the liver, and genes indicating liver inflammation were evaluated. HDEP, ADFI, BW, and egg weight were significantly decreased in the LPHF diet group, while egg weight was also decreased in the LP diet group. In the young hens (LPHF group), ALP was found significantly higher at 30 d of diet treatment and was numerically higher throughout the experiment, while AST was significantly higher at 105 d of treatment. LCS, LHS, and LFC were significantly higher in young hens on the LPHF diet treatment. A liver histological examination shows more lipid vacuolization in the LPHF treatment diet. HF or LP alone had no significant effect on LFC, LHS, or LCS. We suggest that LP in the diet with higher ME from fat can be a possible natural cause for predisposing laying hens to FLHS.

Pharmacological Inhibition of KIT Activates MET Signaling in Gastrointestinal Stromal Tumors

Gastrointestinal stromal tumors (GIST) are the most common adult sarcomas and the oncogenic driver is usually a KIT or PDGFRA mutation. Although GISTs are often initially sensitive to imatinib or other tyrosine kinase inhibitors, resistance generally develops, necessitating backup strategies for therapy. In this study, we determined that a subset of human GIST specimens that acquired imatinib resistance acquired expression of activated forms of the MET oncogene. MET activation also developed after imatinib therapy in a mouse model of GIST (KitV558del/+ mice), where it was associated with increased tumor hypoxia. MET activation also occurred in imatinib-sensitive human GIST cell lines after imatinib treatment in vitro. MET inhibition by crizotinib or RNA interference was cytotoxic to an imatinib-resistant human GIST cell population. Moreover, combining crizotinib and imatinib was more effective than imatinib alone in imatinib-sensitive GIST models. Finally, cabozantinib, a dual MET and KIT small-molecule inhibitor, was markedly more effective than imatinib in multiple preclinical models of imatinib-sensitive and imatinib-resistant GIST. Collectively, our findings showed that activation of compensatory MET signaling by KIT inhibition may contribute to tumor resistance. Furthermore, our work offered a preclinical proof of concept for MET inhibition by cabozantinib as an effective strategy for GIST treatment.

Increased KIT inhibition enhances therapeutic efficacy in gastrointestinal stromal tumor

PURPOSE

Gastrointestinal stromal tumor (GIST) is the most common human sarcoma and a model of targeted molecular therapy. GIST depends on oncogenic KIT signaling and responds to the tyrosine kinase inhibitor imatinib. However, imatinib is rarely curative. We hypothesized that PLX3397, which inhibits KIT and colony-stimulating-factor-1 receptor (CSF1R), would be more efficacious than imatinib in GIST by also depleting tumor-associated macrophages, which are generally thought to support tumor growth.

EXPERIMENTAL DESIGN

We treated Kit(V558del/+) mice that develop GIST or mice with subcutaneous human GIST xenografts with imatinib or PLX3397 and analyzed tumor weight, cellular composition, histology, molecular signaling, and fibrosis. In vitro assays on human GIST cell lines were also performed.

RESULTS

PLX3397 was more effective than imatinib in reducing tumor weight and cellularity in both Kit(V558del)(/+) murine GIST and human GIST xenografts. The superiority of PLX3397 did not depend on depletion of tumor-associated macrophages, because adding CSF1R inhibition did not improve the effects of imatinib. Instead, PLX3397 was a more potent KIT inhibitor than imatinib in vitro. PLX3397 therapy also induced substantial intratumoral fibrosis, which impaired the subsequent delivery of small molecules.

CONCLUSIONS

PLX3397 therapy has greater efficacy than imatinib in preclinical GIST models and warrants study in patients with GIST. The resultant intratumoral fibrosis may represent one of the barriers to achieving complete tumor eradication.

KIT oncogene inhibition drives intratumoral macrophage M2 polarization

Imatinib reduces tumor cell KIT signaling and causes tumor cell apoptosis, which drives TAMs to shift from M1- to M2-like in mouse and human GIST.

Tumor-associated macrophages (TAMs) are a major component of the cancer microenvironment. Modulation of TAMs is under intense investigation because they are thought to be nearly always of the M2 subtype, which supports tumor growth. Gastrointestinal stromal tumor (GIST) is the most common human sarcoma and typically results from an activating mutation in the KIT oncogene. Using a spontaneous mouse model of GIST and 57 freshly procured human GISTs, we discovered that TAMs displayed an M1-like phenotype and function at baseline. In both mice and humans, the KIT oncoprotein inhibitor imatinib polarized TAMs to become M2-like, a process which involved TAM interaction with apoptotic tumor cells leading to the induction of CCAAT/enhancer binding protein (C/EBP) transcription factors. In human GISTs that eventually developed resistance to imatinib, TAMs reverted to an M1-like phenotype and had a similar gene expression profile as TAMs from untreated human GISTs. Therefore, TAM polarization depends on tumor cell oncogene activity and has important implications for immunotherapeutic strategies in human cancers.

Magnetic resonance imaging in the evaluation of osteochondritis dissecans of the patella

OBJECTIVE

The objective was to evaluate the magnetic resonance (MR) appearance of patellar osteochondritis dissecans (OCD).

MATERIALS AND METHODS

We retrospectively analyzed MR images of 16 patients (18 cases, mean age 20 years) using OCD of the patella. In 5 cases surgery was carried out, and we compared the surgical findings with the MR imaging findings in these cases.

RESULTS

In all 18 cases, OCD was located central-inferiorly on the patella, and the average size was 11 x 11 x 7 mm. Subchondral deformities were present in 16 out of 18 cases (88.9%), subchondral cyst formation in 4 cases (22.2%), reactive bone marrow signal in 8 cases (44.4%), overlying patellar cartilage abnormality in 14 cases (77.8%), loose body in 2 cases (11.1%), patella alta in 8 cases (44.4%), hypoplastic sulcus in 7 cases (38.9%), and synovitis in 4 cases (22.2%). In all 5 cases in which surgery was carried out, the cartilage abnormality classified on the MR images was confirmed, and a loose body was removed at arthroscopy in 2 of the 5 cases.

CONCLUSION

Magnetic resonance imaging of patellar OCD typically shows subchondral deformity and variable abnormalities of the overlying patellar cartilage located central-inferiorly on the patella.

Real-time computed tomography image update for endoscopic skull base surgery

INTRODUCTION

The development of computer-aided systems for endoscopic sinus surgery has enabled surgical navigation through diseased or surgically altered sinus anatomy with increased confidence. However, conventional computer-aided systems do not provide intra-operative updated computed tomography imaging. We describe the technical aspects of the xCAT, a new intra-operative mobile volume computed tomography scanner.

TECHNICAL REPORT

A patient with a malignant melanoma unwittingly removed at another hospital underwent surgery for removal of the lateral nasal wall and directed biopsies, in an attempt to identify the site of tumour origin. The procedure was performed with the GE InstaTrak 3500 Plus computer-aided system, updated with intra-operative computed tomography images. Intra-operative, updated images were integrated successfully into the InstaTrak system, and these images were consistent with the observed endoscopic anatomy.

CONCLUSION

The xCAT intra-operative mobile volume computed tomography scanner is a technological advancement that can assist the endoscopic sinus surgeon when performing complex rhinological and skull base procedures.

Kir 4.1 channel expression in neuroblastomaxglioma hybrid NG108-15 cell line

To study a possible involvement of inwardly rectifying K+ 4.1 (Kir 4. 1) channels in neural cell development, RT-PCR, immunocytochemistry and whole-cell patch-clamp techniques were used to assess expression of Kir 4.1 channels in proliferating and differentiated NG108-15 cells. RT-PCR revealed co-expression of Kir 4.1 and rat ether-a-go-go-related gene (R-ERG) mRNAs in both proliferating and differentiated cells. The relative Kir 4.1 mRNA concentration increased markedly as cells progressed from undifferentiated to differentiated cells. Kir 4.1-immunoreactivity was barely detectable in undifferentiated cells, but clearly detected in differentiated cells, indicating that Kir 4.1 gene and protein expressions are developmentally regulated. However, corresponding Kir 4.1 current could not be detected in differentiated cells using whole-cell patch-clamp recording. The 'silent' channel/receptor, often found in tumor cells, may carry genetic defects, which prevent functional expression of the channel. NG108-15 may serve as unique model for studying the relationship between the expression of an ion channel gene and the electrophysiological phenotype it encodes.

RAFT1 phosphorylation of the translational regulators p70 S6 kinase and 4E-BP1

The complex of rapamycin with its intracellular receptor, FKBP12, interacts with RAFT1/FRAP/mTOR, the in vivo rapamycin-sensitive target and a member of the ataxia telangiectasia mutated (ATM)-related family of kinases that share homology with the catalytic domain of phosphatidylinositol 3-kinase. The function of RAFT1 in the rapamycin-sensitive pathway and its connection to downstream components of the pathway, such as p70 S6 kinase and 4E-BP1, are poorly understood. Here, we show that RAFT1 directly phosphorylates p70(S6k), 4E-BP1, and 4E-BP2 and that serum stimulates RAFT1 kinase activity with kinetics similar to those of p70(S6k) and 4E-BP1 phosphorylation. RAFT1 phosphorylates p70(S6k) on Thr-389, a residue whose phosphorylation is rapamycin-sensitive in vivo and necessary for S6 kinase activity. RAFT1 phosphorylation of 4E-BP1 on Thr-36 and Thr-45 blocks its association with the cap-binding protein, eIF-4E, in vitro, and phosphorylation of Thr-45 seems to be the major regulator of the 4E-BP1-eIF-4E interaction in vivo. RAFT1 phosphorylates p70(S6k) much more effectively than 4E-BP1, and the phosphorylation sites on the two proteins show little homology. This raises the possibility that, in vivo, an unidentified kinase analogous to p70(S6k) is activated by RAFT1 phosphorylation and acts at the rapamycin-sensitive phosphorylation sites of 4E-BP1.

CAPON: a protein associated with neuronal nitric oxide synthase that regulates its interactions with PSD95

Nitric oxide (NO) produced by neuronal nitric oxide synthase (nNOS) is important for N-methyl-D-aspartate (NMDA) receptor-dependent neurotransmitter release, neurotoxicity, and cyclic GMP elevations. The coupling of NMDA receptor-mediated calcium influx and nNOS activation is postulated to be due to a physical coupling of the receptor and the enzyme by an intermediary adaptor protein, PSD95, through a unique PDZ-PDZ domain interaction between PSD95 and nNOS. Here, we report the identification of a novel nNOS-associated protein, CAPON, which is highly enriched in brain and has numerous colocalizations with nNOS. CAPON interacts with the nNOS PDZ domain through its C terminus. CAPON competes with PSD95 for interaction with nNOS, and overexpression of CAPON results in a loss of PSD95/nNOS complexes in transfected cells. CAPON may influence nNOS by regulating its ability to associate with PSD95/NMDA receptor complexes.

Expression of agrin in the developing and adult rat brain

Agrin, a synaptic basal lamina protein, is essential for the formation of the vertebrate neuromuscular junction. Agrin's role in synaptogenesis in the central nervous system has, however, not been elucidated. Therefore, we performed immunohistochemical analysis of agrin localization in adult rat brain using agrin-specific polyclonal antibodies. Our results show that agrin immunoreactivity is detected in neuronal cells throughout the brain, and that agrin is expressed in many morphologically and neurochemically distinct neuronal populations. Within neurons, agrin-immunoreactive material is present in dendrites. To determine agrin isoform expression in the central nervous system, we analysed the pattern of expression of several isoforms during development of the rat brain. Our results indicate that alternative splicing of agrin is specifically regulated in the nervous system; isoforms of the Y=4 (i.e. Ag x,4,0, Ag x,4,8 and Ag x,4,19), Z=8 and Z=19 type are expressed exclusively in the nervous system. Agrin expression precedes synaptogenesis and is developmentally regulated in neural tissues. To evaluate stimuli that may be involved in the regulation of agrin expression, we monitored the patterns of isoform expression following a depolarizing stimulus. Our results show that agrin expression in the adult hippocampus is regulated in an activity-dependent manner, with kinetics of induction resembling a delayed early response gene.

Inhibition of an inward rectifier potassium channel (Kir2.3) by G-protein betagamma subunits

The molecular basis of G-protein inhibition of inward rectifier K+ currents was examined by co-expression of G-proteins and cloned Kir2 channel subunits in Xenopus oocytes. Channels encoded by Kir2.3 (HRK1/HIR/BIRK2/BIR11) were completely suppressed by co-expression with G-protein betagamma subunits, whereas channels encoded by Kir2. 1 (IRK1), which shares 60% amino acid identity with Kir2.3, were unaffected. Co-expression of Galphai1 and Galphaq subunits also partially suppressed Kir2.3 currents, but Galphat, Galphas, and a constitutively active mutant of Galphail (Q204L) were ineffective. Gbetagamma and Kir2.3 subunits were co-immunoprecipitated using an anti-Kir2.3 antibody. Direct binding of G-protein betagamma subunits to fusion proteins containing Kir2.3 N terminus, but not to fusion proteins containing Kir2.1 N terminus, was also demonstrated. The results are consistent with suppression of Kir2.3 currents resulting from a direct protein-protein interaction between the channel and G-protein betagamma subunits. When Kir2.1 and Kir2.3 subunits were coexpressed, the G-protein inhibitory phenotype of Kir2.3 was dominant, suggesting that co-expression of Kir2.3 with other Kir subunits might give rise to novel G-protein-inhibitable inward rectifier currents.

Binding of the inward rectifier K+ channel Kir 2.3 to PSD-95 is regulated by protein kinase A phosphorylation

Dynamic regulation of ion channel interactions with the cytoskeleton mediates aspects of synaptic plasticity, yet mechanisms for this process are largely unknown. Here, we report that two inwardly rectifying K+ channels, Kir 2.1 and 2.3, bind to PSD-95, a cytoskeletal protein of postsynaptic densities that clusters NMDA receptors and voltage-dependent K+ channels. Kir 2.3 colocalizes with PSD-95 in neuronal populations in forebrain, and a PSD-95/Kir 2.3 complex occurs in hippocampus. Within the C-terminal tail of Kir 2.3, a serine residue critical for interaction with PSD-95, is also a substrate for phosphorylation by protein kinase A (PKA). Stimulation of PKA in intact cells causes rapid dissociation of the channel from PSD-95. This work identifies a physiological mechanism for regulating ion channel interactions with the postsynaptic density.

Cloning and expression of two brain-specific inwardly rectifying potassium channels

We have cloned two inwardly rectifying K+ channels that occur selectively in neurons in the brain and are designated BIRK (brain inwardly rectifying K+) channels. BIRK1 mRNA is extremely abundant and is enriched in specific brainstem nuclei, BIRK1 displays a consensus phosphate-binding loop, and expression in Xenopus oocytes has shown that its conductance is inhibited by ATP and adenosine 5'-[gamma-thio]triphosphate. BIRK2 is far less abundant and is selectively localized in telencephalic neurons. BIRK2 has a consensus sequence for cAMP-dependent phosphorylation.

The iron-responsive element binding protein: a target for synaptic actions of nitric oxide

Molecular targets for the actions of nitric oxide (NO) have only been partially clarified. The dynamic properties of the iron-sulfur (Fe-S) cluster of the iron responsive-element binding protein (IRE-BP) suggested that it might serve as a target for NO produced in response to glutamatergic stimulation in neurons. In the present study, we demonstrate that N-methyl-D-aspartate, acting through NO, stimulates the RNA-binding function of the IRE-BP in brain slices while diminishing its aconitase activity. In addition, we demonstrate a selective localization of the IRE-BP in discrete neuronal structures, suggesting a potential role for this protein in the response of neurons to NO.

Interaction of N,N',N''-triethylenethiophosphoramide and N,N',N''-triethylenephosphoramide with cellular DNA

The antineoplastic agents N,N',N''-triethylenethiophosphoramide (thioTEPA) and N,N',N''-triethylenephosphoramide (TEPA) were studied for their interaction with the DNA of L1210 cells in the presence and absence of rat hepatic microsomes and NADPH. Alkaline elution was used to study 3 types of DNA lesions. When L1210 cells were incubated with thioTEPA alone, or with thioTEPA in the presence of microsomes and NADPH, no single-strand breaks were detected. However, incubation of L1210 cells for 2 h with thioTEPA, at concentrations greater than or equal to 100 microM, caused a dose-dependent increase in interstrand cross-linking that reached a maximum by 2 h after drug exposure. In the presence of rat hepatic microsomes and NADPH, this cross-linking was eliminated, but a different DNA lesion, alkali-labile sites, was produced. These alkali-labile sites were partially reparable with maximum repair achieved by 2 h after removal of drug. ThioTEPA was greater than 85% consumed by the microsomal incubation conditions employed, and TEPA was the only product of the microsomal metabolism of thioTEPA. Alkaline elution studies of L1210 cells that had been incubated with TEPA, alone or in the presence of microsomes and NADPH, demonstrated an elution pattern identical to that produced by thioTEPA in the presence of microsomes and NADPH. Lymphoblastoid cell lines derived from patients with Fanconi's anemia were far more sensitive to thioTEPA and mechlorethamine hydrochloride than were lymphoblasts derived from normal humans, but this hypersensitivity was not noted with TEPA or bleomycin. This is consistent with the known hypersensitivity of cells from patients with Fanconi's anemia to agents that produce interstrand cross-links and with the alkaline elution studies described above. In contrast, lymphoblastoid cell lines derived from patients with ataxia telangiectasia were no more sensitive to thioTEPA than were lymphoblasts derived from normal humans but were far more sensitive to bleomycin. One of these cell lines proved hypersensitive to TEPA, whereas the other was no more sensitive to TEPA than were lymphoblasts from normal humans. Our data imply that thioTEPA produces interstrand cross-links but that TEPA, the primary metabolite of thioTEPA, produces DNA lesions that are alkali labile.

Depression of ventilatory responses to hypoxia and hypercapnia after pentamorphone

Pentamorphone is a novel, potent opiate with rapid onset and short duration of action that has been reported to produce analgesia with limited depression of ventilation. We quantified the effects of pentamorphone (0.08, 0.24, and 0.60 micrograms/kg, IV) on ventilatory responses to hypercapnia and hypoxia in 12 healthy volunteers. Normoxic hypercapnia and isocapnic hypoxia were induced through a rebreathing method. During each test we recorded ventilation (VE), end tidal carbon dioxide tension (PETCO2), and arterial oxygen saturation (SO2) using a pulse oximeter. Using linear regression analysis of the relationships between VE and PCO2 during hypercapnia and VE and SO2 during hypoxia, we determined the slope (slope CO2) and intercept (V55), both at PCO2 55 mm Hg, and the slope (slope O2) and intercept (V80) at SO2 80%. Pentamorphone produced dose-related reductions in the ventilatory responses to both hypercapnia and hypoxia. Maximal depression occurred 15 min after injection of pentamorphone with all doses; the highest dose (0.60 micrograms/kg) produced 48% and 53% reductions in slope CO2 and V55, and 42% and 22% reductions in slope O2 and V80, respectively, relative to parallel saline controls. The respiratory depressant actions of pentamorphone were short-lived, as all parameters returned to baseline levels within 45 min. Testing was continued for 180 min after injection, but no delayed ventilatory effects were detected, and minimal side effects were reported, even at the highest dose. The findings confirm previous reports that pentamorphone has limited ventilatory depressant effects in humans in doses that (in other studies) have been associated with clinically effective analgesia.