Abstract 2213: Comparison of infusion devices for hepatic artery delivery of CAR-T

We previously tested the efficacy of chimeric antigen receptor T cell (CAR-T) treatment via hepatic artery infusion in a phase I clinical trial. Though these results were promising, our current protocol for hepatic immunotherapy for metastasis (HITM) includes transcatheter arterial embolization in order to reduce off-target toxicity from CAR-T delivery to gastric, enteric, or pancreatic tissues. Surefire Infusion System devices employ a soft fabric one way valve that prevents back-flow during hepatic artery infusion and generates a pressure gradient, which is clinically shown to increase delivery of therapeutic agents into tumor. We performed in vitro and in vivo testing in preparation for a phase Ib trial to ensure that the SIS does not adversely affect CAR-T performance. Viability, phenotype and activation status of CAR-T with no catheter (NC) and following passage through a standard microcatheter (STD), Surefire Infusion System (SIS), or Surefire Precision (SP) infusion system were tested via flow cytometry. CAR-T viability was preserved as measured by Zombie NIR. We did not detect a significant phenotype shift when examining CD4, CD8, CD25, and CD69. A CFSE assay and an LDH were done to track proliferation and measure the cytotoxicity of the CAR-T when stimulated by tumor. NC CAR-T had significantly more proliferation than each of the catheter groups. Specific Lysis was not significantly different between the NC, STD, SIS, and SP groups. We also performed in vivo testing in mice with intraperitoneal (IP) tumor with IP NC or SIS CAR-T. By Day 10, there was significantly less tumor present in the NC (5.7- fold reduction, p = 0.02) and the SIS (44- fold reduction, p = 0.04) groups than in the tumor only control group. The SIS CAR-T group and the NC CAR-T group were not significantly different (p = 0.38). The SIS and SP devices did not adversely impact CAR-T viability, phenotype, or performance implying that these catheters could be interchangeably used for more efficient and targeted CAR-T dose delivery.

In Vitro Experimental Data ExperimentNC (Control)STD (Control)SISPSViability (Zombie NIR)6%7.9% p = 0.7 vs NC7.4% p = 0.9 vs. STD9.9% p = 0.7 vs STDPhenotype (CD3+CD4+)33.1%30.6% p = 0.9 vs NC33.3% p = 0.9 vs STD21.3% p = 0.8 vs STDPhenotype (CD3+CD8+)68.8%69.5% p = 0.9 vs NC69.1% p = 0.9 vs STD66.7% p = 0.7 vs STDActivation (CD69+)34.93%32.3% p = 0.9 vs NC33% p = 0.9 vs STD25.6% p = 0.7 vs STDTreg (CD25+)35.2%36.2% p = 0.9 vs NC36.8% p = 0.6 vs STD40.5% p = 0.6 vs STDProliferation (CFSE)41.7%26.7% p = 0.005 vs NC27.3% p = 0.8 vs STD24.2% p = 0.4 vs STDCytotoxicity (LDH Assay)51.2%42.1% p = 0.1 vs NC44% p = 0.7 vs STD41.1% p = 0.9 vs STD

Citation Format: Josephine K. Darpolor, Marissa Cunetta, Matthew Lima, Jillian Gardell, Gary Point, Zhi Liu, N J. Espat, Prajna Guha, Steven Katz. Comparison of infusion devices for hepatic artery delivery of CAR-T. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2213.

Abstract 2301: Intraperitoneal CAR-T infusion results in durable protection against peritoneal metastases and control of systemic tumor growth

Colorectal carcinomatosis due to peritoneal metastases (PM) is a significant cause of morbidity and mortality. Present treatments fail to cure the majority of patients with PM. We are developing a chimeric antigen receptor T cell (CAR-T) regional infusion immunotherapy platform for PM. We treated mice with established CEA+ MC38 PMs with anti-CEA CAR-Ts either via regional intraperitoneal (IP) or systemic tail vein (TV) infusion. When compared to TV infusion, IP delivery resulted in significantly improved responses (37-fold reduction in tumor growth, p<0.01). To measure the durability of protection from IP tumor growth, we re-challenged mice with IP tumor following successful treatment with IP CAR-Ts. Mice who had received initial IP CAR-T treatment were protected from tumor growth following re-challenge for 20 days compared to control animals (1390-fold reduction in tumor growth, p = 0.016). Assessment of IP tumor 10 and 28 days following tumor re-challenge revealed a high proportion of intratumoral CAR-Ts (Day 10- 70.0%, Day 28- 46.6%; p = 0.10) and the proportion of CAR-Ts with an effector memory phenotype (CD44+CD62L-CCR7-, Day 10- 19.3%, Day 28- 60.0%; p<0.01). In separate experiments, we studied the effect of IP CAR-T infusions on tumor growth at distant sites. We established both IP and subcutaneous (SQ) flank tumors in mice prior to CAR-T infusions. Following treatment, IP CAR-T infusion resulted in a significant decrease in SQ tumor growth on day 8 compared to control (5.7-fold, p = 0.03), and a trend toward improvement compared to TV (4.9-fold, p = 0.224). While CAR-Ts were not detected in whole blood, SQ tumor, or draining lymph nodes following IP CAR-T infusion, serum IFNγ levels were significantly elevated on day 4 compared to control mice (p = 0.04), and returned to baseline by day 7. Our findings demonstrate that regional IP CAR-T delivery provides durable protection against IP tumor growth in association with CAR-T effector memory programming, in addition to a systemic anti-tumor effect.

Citation Format: Marissa Cunetta, Gary Point, Zhi Liu, Prajna Guha, Josephine Darpolor, Matthew Lima, N J. Espat, Nader Hanna, Cherif Boutros, Richard P. Junghans, Steven Katz. Intraperitoneal CAR-T infusion results in durable protection against peritoneal metastases and control of systemic tumor growth. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2301.

Abstract 2212: Induction of α5β1 integrin expression rescues geriatric CAR-T cell function

Chimeric antigen receptors expressing T cells (CAR-Ts) are a promising form of immunotherapy for solid tumors. The majority of cancer patients in the United States are over 65 years old. The impact of age-related physiologic changes on cancer therapy and immunotherapy in particular require further study. We tested our hypothesis that CAR-T from geriatric donors (gCAR-T, n = 8, >65 years) are functionally impaired relative to CAR-T from younger donors (yCAR-T, n = 8, 18-45 years). T cells were genetically modified to express CAR specific for carcino-embryonic antigen (CEA), presently in use in our phase I trials. CAR-T cells were expanded ex vivo with IL2 (3000IU/ml) or IL15 (5ng/ml) for 20 days. Higher transduction efficiencies (36.9%+4.3 yCAR-T vs 21.3%+2.2 gCAR-T, p = 0.002) and improved cell expansion (2.5 fold in IL2, p = 0.01, two-tailed t-test) were observed in yCAR-T cells compared to gCAR-T. To define the underlying signaling mechanisms that led to increased proliferation in yCAR-T cells, we examined pERK, pAKT, pSTAT3 and pSTAT5. Following activation with anti-CD3, yCAR-T demonstrated significantly increased levels of pERK (13.4 fold in IL2, p = 0.03 and 2.3 fold in IL15, p = 0.04), pAKT (4.2 fold in IL2, p = 0.04 and 3.0 fold in IL15, p = 0.04), pSTAT3 (1.5 fold in IL2, p = 0.02 and 2.9 fold in IL15, p = 0.01) and pSTAT5 (5.7 fold in IL2, p = 0.02 and 2.1 fold in IL15, p = 0.03) compared to gCAR-T. Furthermore, yCAR-T contained higher proportions of CD4 effector cells (EC) (p = 0.003), CD4 effector memory (EM) cells (p = 0.002) and CD8 effector memory cells (EM) (p = 0.002). In accordance with higher numbers of CD4 and CD8 EM, yCAR-T demonstrated higher levels of CEA specific cytotoxicity compared to gCAR-T (1.3-fold over gCAR-T, p = 0.03), with maximum cytotoxicity observed in IL15 treated yCAR-T cells. Enhanced tumor killing by yCAR-T correlated with increased levels of perforin (1.3+0.1 ng/ml, p = 0.01) and granzyme B (0.4+0.03 ng/ml, p = 0.02). Unmodified geriatric T cells (gT) had decreased α5β1 integrin expression as compared to unmodified young T cells (yT) (yT cells 44.4 +4.2 vs gT cells 22.3 +2.0, p = 0.0003), a known mediator of retroviral transduction. We found that M-CSF or TGF-β1 rescued CAR expression by gCAR-T (yCAR-T 36.9+4.3, gCAR-T 29.9+1.0, gT+M-CSF 41.4+1.0, gT+TGF-β1 40.1+2.0, p<0.002 vs gCAR-T) through restoring α5β1 integrin expression (gT cells +M-CSF 41.0+1.0, gT cells + TGF- β1 31.8+1.4, yT cells 44.41 +4.2, p<0.0005). We performed cytotoxicity assays and demonstrated that M-CSF and TGF-β1 (up to 1.5 fold over untreated gCAR-T, p<0.05) rescued g-CAR-T tumor killing function. Our study suggests that functional impairment of gCAR-T can be mitigated through M-CSF of TGF-β1 treatment to restore α5β1 integrin expression.

Citation Format: Prajna Guha, Marissa Cunetta, Ponnandai Somasundar, N J. Espat, Richard P. Junghans, Steven C. Katz. Induction of α5β1 integrin expression rescues geriatric CAR-T cell function. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2212.

Neutrophil:lymphocyte ratios and serum cytokine changes after hepatic artery chimeric antigen receptor-modified T-cell infusions for liver metastases

Introduction

Our phase I Hepatic Immunotherapy for Metastases (HITM) trial tested the safety of chimeric antigen receptor modified T cell (CAR-T) hepatic artery infusions (HAI) for unresectable CEA+ liver metastases (LM). High neutrophil:lymphocyte ratios (NLR) predict poor outcome in cancer patients and we hypothesized that NLR changes would correlate with early responses to CAR-T HAI.

Methods

Six patients completed the protocol. Three patients received CAR-T HAI in dose escalation (1 × 10⁸, 1 × 10⁹, and 1 × 10¹⁰cells) and the remainder received 3 doses (1 × 10¹⁰ cells) with IL2 support. Serum cytokines and NLR were measured at multiple time points.

Results

The mean NLR for all patients was 13.9 (range 4.8-38.1). NLR increased in four patients following treatment with a mean fold change of 1.9. Serum IL6 levels and NLR fold-changes demonstrated a trend towards a positive correlation (r=0.77, p=0.10). Patients with poor CEA responses were significantly more likely to have higher NLR level increases (p=0.048).

Conclusions

Increased NLR levels were associated with poor responses following CAR-T HAI. NLR variations and associated cytokine changes may be useful surrogates of response to CAR-T HAI.

Consensus guidelines from The American Society of Peritoneal Surface Malignancies on standardizing the delivery of hyperthermic intraperitoneal chemotherapy (HIPEC) in colorectal cancer patients in the United States

BACKGROUND

The American Society of Peritoneal Surface Malignancies (ASPSM) is a consortium of cancer centers performing cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (HIPEC). This is a position paper from the ASPSM on the standardization of the delivery of HIPEC.

METHODS

A survey was conducted of all cancer centers performing HIPEC in the United States. We attempted to obtain consensus by the modified method of Delphi on seven key HIPEC parameters: (1) method, (2) inflow temperature, (3) perfusate volume, (4) drug, (5) dosage, (6) timing of drug delivery, and (7) total perfusion time. Statistical analysis was performed using nonparametric tests.

RESULTS

Response rates for ASPSM members (n = 45) and non-ASPSM members (n = 24) were 89 and 33 %, respectively. Of the responders from ASPSM members, 95 % agreed with implementing the proposal. Majority of the surgical oncologists favored the closed method of delivery with a standardized dual dose of mitomycin for a 90-min chemoperfusion for patients undergoing cytoreductive surgery for peritoneal carcinomatosis of colorectal origin.

CONCLUSIONS

This recommendation on a standardized delivery of HIPEC in patients with colorectal cancer represents an important first step in enhancing research in this field. Studies directed at maximizing the efficacy of each of the seven key elements will need to follow.

Confirmed angiosarcoma: prognostic factors and outcome in 50 prospectively followed patients

Purpose. Angiosarcoma is a rare tumor with endothelial cell differentiation that may arise in any anatomic location.The purpose of this report was to identify prognostic factors on outcome in a group of prospectively followed patients with confirmed angiosarcoma.Subjects. Adult patients (>16 years old) with angiosarcoma treated between July 1982 and February 1998 were identified from a prospective database.Methods. Pathologic confirmation of all cases was performed prior to inclusion in this analysis. Various prognostic factors were evaluated for disease-specific survival. Survival was determined by the Kaplan- Meier method. Statistical significance was evaluated by log-rank test for univariate analysis and Cox stepwise regression for multivariate analysis (p<0.05).Results. Fifty patients were identified; at the initial evaluation, this group included 32 patients with a primary tumor, three with local recurrence and 15 with metastatic disease. Tumor sites included 16 head and neck and skin of head, eight extremity, seven trunk, six breast, five pelvis, four viscera and four thoracic. Median follow-up among survivors was 71 months (range, 38-191 months).Two- and 5-year disease-specific survival was 50 and 30%, respectively, with a median of 24 months. The factor predictive of tumor-related mortality was presentation status (p=0.001; relative risk, 5). Two-year disease-specific survival for patients presenting with recurrent or metastatic disease was 13%, compared with 70% for those with primary disease.

Low common bile duct bifurcation incidentally discovered during pancreaticoduodenectomy

INTRODUCTION

Bile duct injury due to failure to recognize anatomical variations can have considerable consequences.

DISCUSSION

We report an incidental discovery of a low common bile duct bifurcation below the level of the cystic duct, incidentally discovered during pancreaticoduodenectomy.

Microwave coagulation therapy for hepatic tumors: review of the literature and critical analysis

BACKGROUND

Surgical resection of malignant hepatic tumors has been demonstrated to increase overall survival; however, the majority of patients are not candidates for resection. For patients with unresectable tumors, various chemical and thermal ablation modalities have been developed. microwave coagulation therapy (MCT) is one such thermal ablation modality and the purpose of this review is to evaluate the presently available data for MCT and assess the level of evidence to support its clinical use.

METHODS

This review is limited to published studies in the English literature including at least 30 patients per study with MCT for hepatocellular cancer (HCC) or colorectal hepatic metastasis (CRHM). Patterns of local recurrence, complications and survival outcome of MCT ablation are presented and discussed including assessment of Asian experience using the 2.4GHZ device and American experience using the 914MHZ device.

CONCLUSIONS

Although randomized controlled trials comparing RFA and MCT for hepatic ablation are lacking, our review (based on level 2 data) supports that MCT may be optimal when larger necrosis zones and/or ablation of multiple lesions are the objectives. The data support that the potential procedural advantage(s) noted for ablation of CRHM and HCC >3cm, is not supported for HCC <3cm; moreover MCT shares with all other ablation modalities a high rate of locoregional recurrence in HCC; likely due to the multicentricity of this disease process.

Robotically assisted laparoscopic transhiatal esophagectomy

BACKGROUND

Esophagectomy is a technically demanding operation with high procedure-related morbidity and mortality rates. Minimally invasive techniques were introduced in the late 1980s in an effort to decrease the invasiveness of the procedure. Data concerning the use of robotic systems for esophageal cancer are scarce in the literature. The goal of this report is to describe the authors' early experience using robotically assisted technology to perform transhiatal esophagectomy (RATE).

METHODS

Between September 2001 and May 2004, 18 patients underwent RATE at the authors' institution. A retrospective review of prospectively collected data was performed. Gender, age, postoperative diagnosis, operative time, conversion rate, blood loss, hospital stay, length of the follow-up period, and complications were assessed.

RESULTS

At the authors' institution, 18 patients underwent RATE, including 16 men (89%), with a mean age of 54 years (range, 41-73 years). The RATE procedure was completed for all 18 patients (100%). The mean operative time was 267 +/- 71 min, and estimated blood loss was 54 ml (range, 10-150 ml). The mean intensive care unit stay was 1.8 days (range, 1-5 days), and the mean hospital stay was 10 days (range, 4-38 days). A total of 12 perioperative complications occurred for 9 patients, including 6 anastomotic leaks, 1 thoracic duct injury, 1 vocal cord paralysis, 1 pleural effusion, and 2 atrial fibrillations. Anastomotic stricture was observed in six patients. There were no perioperative deaths. Pathologic examination of the surgical specimen yielded an average of 14 lymph nodes per patient (range, 7-27). During the mean follow-up period of 22 +/- 8 months, 2 patients died, 2 were lost to follow-up evaluation, 3 had recurrence, and 11 were disease free.

CONCLUSION

The current study shows that RATE, with its decreased blood loss, minimal cardiopulmonary complications, and no hospital mortality, represents a safe and effective alternative for the treatment of esophageal adenocarcinoma.

Robotic-assisted thoracoscopic resection of esophageal leiomyoma

Esophageal leiomyoma represents 70-80% of all benign esophageal tumors but only approximately 0.5% of all esophageal neoplasms; optimal surgical treatment consists of local resection. We present the first reported robotic-assisted thoracoscopic resection of two patients with esophageal leiomyoma using the daVinci Surgical System. Operative technique and technical considerations are presented.

Omega-3 fatty acid supplementation reduces tumor growth and vascular endothelial growth factor expression in a model of progressive non-metastasizing malignancy

BACKGROUND

Omega-3 fatty acids, the principal component of fish oil, have been demonstrated to have antiinflammatory properties. The role of eicosapentaenoic acid (EPA) supplementation for cancer patients is currently under investigation; however, the mechanisms of EPA activity have not been defined. The purpose of this study was to characterize tumor-specific and treatment-specific effects of supplemental dietary EPA in an animal model of progressive malignancy.

METHODS

Fischer 344 rats (200-250 g) underwent flank implantation of the methycholanthrene (MCA)-induced fibrosarcoma on day 0. Rats were randomly divided into 3 treatment groups on day 13: EPA (1 mL, 5.0 g/kg per day) + 10 IU vitamin E; corn oil (1 mL) + 10 IU vitamin E, and saline (1 mL) + 10 IU vitamin E (vitamin E was used to prevent fatty acid oxidation). On day 14, gavage feeding was started and was continued through day 28. The animals were killed on day 29, and the tumors were removed. The tumors were weighed and divided by the tumor-free carcass weight to obtain percentage of tumor volume, and the livers were flash frozen. Vascular endothelial growth factor-alpha (VEGF-alpha) and cyclo-oxygenase 2 (COX-2) mRNA were measured by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

EPA rats had significant reductions in tumor volume compared with isocaloric corn oil and control saline animals (25%, p < .01 and 33%, p < .01, respectively). Rats receiving EPA demonstrated decreased VEGF-alpha mRNA levels (0.023 +/- 0 0.001) compared with those receiving corn oil (0.129 +/- 0.047) or saline (0.150 +/- 0.026; p < .05).

CONCLUSIONS

These data demonstrate that EPA supplementation inhibits tumor growth, potentially through alterations in the expression of the pro-angiogenic VEGF-alpha. The mechanism(s) of EPA as an inhibitor of tumor-related angiogenic growth factors may be associated with COX-2 enzyme fatty acid metabolism and merits further study.

Histologic characterization of acute spinal cord injury treated with intravenous methylprednisolone

OBJECTIVE

Many substances have been investigated for attenuation of spinal cord injury after acute trauma; however, pharmacologically only steroid administration has shown clinical benefits. This study attempts to characterize local spinal cord histologic response to human dose equivalent (HDE) intravenous methylprednisolone (MP) administration in a rodent model of acute spinal cord injury.

DESIGN

Forty-eight Sprague-Dawley rats were divided equally into control and experimental groups. Each group was subdivided into eight sets of three animals each, according to postinjury intervals. Paraplegia after lower thoracic laminectomy was achieved using a standardized weight drop technique.

INTERVENTION

Within one hour, experimental animals were treated with HDE MP followed by 23-hour continuous infusion of HDE MP. Spinal cords were harvested at variable intervals postinjury and prepared for histologic/immunohistochemistry examination.

MAIN OUTCOME MEASUREMENTS

Edema, necrosis, and glial fibrillary acidic protein (GFAP) positivity in the specimens from treated/control groups were graded by microscopy and immunohistochemistry staining and compared in a blinded manner by a qualified neuropathologist and senior authors.

RESULTS

Minimal differences were observed between control and MP-treated animals at zero and four hours. At eight hours, increased white matter and medullary edema was evident in control versus MP-treated rats. This trend continued through twelve, sixteen, twenty-four, forty-eight, and seventy-two hours. No difference was observed in the astrocytic response to injury by GFAP immunohistochemistry between the groups.

CONCLUSIONS

Histologically, MP reduces the development of severe edema and preserves spinal cord architecture adjacent to the site of injury. In contrast, MP does not alter the development of spinal cord necrosis or astrocytic response at the zone of injury.

Pancreatic heterotopia and other uncommon causes of non-malignant biliary obstruction

The vast majority of patients developing obstructive jaundice will have an underlying malignancy. When the etiology of the obstruction cannot be defined prior to operative intervention, identification of a non-malignant process will occur only subsequent to a major operation. The clinical course of a patient with complete distal common bile duct obstruction as the result of pancreatic heterotopia is discussed. This uncommon diagnosis prompted a review of the literature on this subject enabling this detailed discussion inclusive of the embryology, prevalence and clinical presentations of this entity. Our review further identified a varied group of other non-malignant causes of biliary obstruction that may be mistakenly interpreted to represent biliary or pancreatic malignancy.

Palliative strategies for locally advanced unresectable and metastatic pancreatic cancer

Technical improvement in perioperative morbidity and mortality with improved long-term survival associated with pancreaticoduodenectomy for patients with pancreatic carcinoma has clearly established a role for this operation when performed with curative intent. Most patients with pancreatic adenocarcinoma will not be candidates for surgical resection of their disease. These patients will experience significant symptoms potentially requiring surgical and nonsurgical palliative interventions to treat unrelieved cancer-associated pain, obstructive jaundice, or the development of GOO. The primary goal for palliative interventions should be to relieve symptoms with minimal morbidity and to maintain or improve the quality of life for patients with an expected limited survival.

The relationship between visceral ischemia, proinflammatory cytokines, and organ injury in patients undergoing thoracoabdominal aortic aneurysm repair

OBJECTIVES

Plasma proinflammatory, anti-inflammatory cytokine, and soluble tumor necrosis factor (TNF) receptor concentrations were examined in hospitalized patients after abdominal and thoracoabdominal aortic aneurysm (TAAA) repair, with and without left atrial femoral bypass. Changes in plasma cytokine concentrations were related to the duration of visceral ischemia and the frequency rate of postoperative, single, or multiple system organ dysfunction (MSOD).

DESIGN

Prospective, observational study.

SETTING

Two academic referral centers in the United States and The Netherlands.

PATIENTS

We included 16 patients undergoing TAAA repair without left atrial femoral bypass, 12 patients undergoing TAAA repair with left atrial femoral bypass, and nine patients undergoing infrarenal aortic aneurysm repair.

MEASUREMENTS AND MAIN RESULTS

Timed, arterial blood sampling for proinflammatory and anti-inflammatory cytokine and soluble TNF receptor concentrations (p55 and p75), and prospective assessment of postoperative single and MSOD. Plasma appearance of TNF-alpha, interleukin (IL)-6, IL-8, and IL-10 peaked 1 to 4 hrs after TAAA repair, and concentrations were significantly elevated compared with infrarenal abdominal aortic aneurysm repair (p < .05). Left atrial femoral bypass significantly reduced the duration of visceral ischemia (p < .05) and the systemic TNF-alpha, p75, and IL-10 responses (p < .05). Plasma TNF-alpha concentrations >150 pg/mL were more common in patients with extended visceral ischemia times (>40 mins). Additionally, patients with early peak TNF-alpha concentrations >150 pg/mL and IL-6 levels >1,000 pg/mL developed MSOD more frequently than patients without these elevated plasma cytokine levels (both p < .05).

CONCLUSIONS

Thoracoabdominal aortic aneurysm repair results in the increased plasma appearance of TNF-alpha, IL-6, IL-8, IL-10, and shed TNF receptors. The frequency and magnitude of postoperative organ dysfunction after TAAA repair is associated with an increased concentration of the cytokines, TNF-alpha, and IL-6 and the increased plasma levels of these cytokines appear to require extended visceral ischemia times.

The biological significance of failure at the primary site on ultimate survival in soft tissue sarcoma

Local tumor recurrence after complete resection may be due to treatment factors or represent a manifestation of tumor biology. The association of local tumor recurrence, distant metastases, and death in patients undergoing treatment for extremity soft tissue sarcoma (STS) has been described but continues to be enigmatic. After definitive multimodality treatment for extremity STS, local tumor recurrence is associated with development of distant metastasis, and metastases are implicated in subsequent disease-specific death. The relationship is an enigma, and the causality is unclear. Conversely, for patients with retroperitoneal STS, a direct relationship between local tumor recurrence and disease-specific death has been shown. In this article, current concepts are analyzed and reviewed.

Patients with laparoscopically staged unresectable pancreatic adenocarcinoma do not require subsequent surgical biliary or gastric bypass

BACKGROUND

Laparoscopic staging is an effective and accurate means of staging pancreatic cancer. But, the frequency of subsequent surgical bypass to treat biliary or gastric obstruction in laparoscopically staged patients with unresectable adenocarcinoma is unknown. The development of biliary and gastric obstruction in patients with unresectable pancreatic adenocarcinoma has been reported to occur in as many as 70% and 25% of patients, respectively. Previously, staging for patients with pancreatic cancer was achieved by laparotomy and the anticipated high rate for these patients to develop obstruction led to prophylactic bypass procedures. As laparoscopic staging for pancreatic cancer becomes a standard modality, the need for prophylactic bypass procedures in these patients needs to be examined.

STUDY DESIGN

Analyses of laparoscopically staged patients (n = 155) with unresectable, histologically proved pancreatic adenocarcinoma, from a single institution treated between 1993-1997 were performed. The frequency of surgical bypass in a prospective cohort of patients with unresectable pancreatic adenocarcinoma who did not undergo open enteric or biliary bypass at the time of laparoscopic staging was determined.

RESULTS

Laparoscopic staging revealed that 40 patients had locally advanced disease and 115 had metastatic disease. Median survival for patients with locally advanced and metastatic disease was 6.2 and 7.8 months, respectively. Postlaparoscopy followup revealed that 98% (152 of 155) of these patients did not require a subsequent open surgical procedure to treat biliary or gastric obstruction.

CONCLUSIONS

These results do not support the practice of routine prophylactic bypass procedures. As such, we propose that surgical biliary bypass can be advocated only for those patients with obstructive jaundice who fail endoscopic stent placement, and gastroenterostomy should be reserved for patients with confirmed gastric outlet obstruction.

Reconstruction following total gastrectomy: a review and summary of the randomized prospective clinical trials

Reconstruction of gastrointestinal tract continuity following total gastrectomy can be achieved using a variety of operations. Worldwide, Roux-en-Y esophago-jejunostomy with or without a pouch reservoir, is the most frequently performed operation after total gastrectomy. Others have advocated the preservation of the duodenal food passage, employing an interposed segment of bowel between the esophageal remnant and duodenum as a more physiologic operation. Several methods for either approach are described. In recent years, six randomized prospective clinical trials assessing various operations for gastrointestinal reconstruction have been reported. While there is a general consensus for the indications and patient selection criteria in order to proceed with total gastrectomy, a defined optimal procedure has not been clearly established. In the present work, these recent clinical studies addressing gastrointestinal reconstruction following total gastrectomy are reviewed and summarized.

Interleukin 6, but not ciliary neurotrophic factor or leukaemia inhibitory factor, is responsible for the acute phase response to turpentine-induced myositis

The acute phase response to inflammation is mediated in part by the endogenous production of pro-inflammatory cytokines. Interleukin 6 (IL-6) and members of its superfamily, including ciliary neurotrophic factor (CNTF) and leukaemia inhibitory factor (LIF) have been implicated as primary mediators of the hepatic acute phase response. In the present report, mice suffering a turpentine-induced myositis were passively immunized with antibodies against either IL-6, CNTF or LIF. Passive immunization against IL-6 attenuated the anorexia and completely prevented the hypoalbuminaemia, and increases in the serum concentration of the acute phase reactants, amyloid P, amyloid A and seromucoid. In contrast, passive immunization against either CNTF or LIF failed to modulate the anorexia, weight loss or hepatic acute phase protein responses. The findings suggest that IL-6, but not other members of its superfamily, is primarily responsible for the hepatic acute phase response, and contributes to the anorexia, associated with turpentine-induced myositis.

Ciliary neurotrophic factor is catabolic and shares with IL-6 the capacity to induce an acute phase response

Ciliary neurotrophic factor (CNTF), a member of the interleukin-6 (IL-6) superfamily, has recently been shown to induce several inflammatory responses when administered to healthy animals, including induction of fever and a hepatic acute phase protein response. In the present report, 250 micrograms.kg body wt-1.day-1 of recombinant rat CNTF or murine IL-6 were repeatedly administered to healthy mice over a 7-day period in an effort to compare biological responses. In addition to its in vivo capacity to elicit a hepatic acute phase response, administration of CNTF, but not IL-6, produced profound anorexia and lean tissue wasting in mice. In C57B1/6 mice, 7 days of CNTF administration led to a 21% loss in carcass protein content, resulting from carcass protein breakdown rates being increased 218% over freely fed controls (both P < 0.01). Protein synthesis rates in carcass protein were also increased in CNTF-treated mice compared with both freely fed animals and mice pair-fed equivalent quantities of food. In contrast, administration of equivalent quantities of murine IL-6 had no effect on food intake or body weight in mice, although IL-6 produced a similar hepatic acute phase response, as determined by increases in serum amyloid P and seromucoid fraction and increases in total hepatic protein synthesis. However, when CNTF was coincubated with extensor digitorum longus muscles from juvenile rats in vitro, rates of total muscle and myofibrillar protein degradation and muscle protein synthesis were unchanged. We conclude that CNTF can regulate in vivo both skeletal muscle remodeling as well as the distant anorexia and hepatic acute phase protein responses. In the case of skeletal muscle, these actions are both indirect and independent of the associated anorexia. These properties of CNTF are distinct from IL-6, which when administered to the mouse at these doses is neither anorexigenic nor cachexia producing.

Dietary modulation of amino acid transport in rat and human liver

Specialized diets enriched in the amino acids glutamine and arginine have been shown to benefit surgical patients. In the liver, glutamine supports glutathione biosynthesis, arginine regulates nitric oxide synthesis, and both of these amino acids serve as precursors for ureagenesis, gluconeogenesis, and acute phase protein synthesis. The effects of a diet enriched with glutamine and arginine on hepatic plasma membrane transport activity have not been studied in humans. We hypothesized that feeding supradietary amounts of these nutrients would enhance the activities of the specific carriers which mediate their transmembrane transport in the liver. We fed surgical patients (n = 8) and rats (n = 6) one of three diets: a) a regular diet, b) an enteral liquid diet containing arginine and glutamine, or c) an enteral diet supplemented with pharmacologic amounts of glutamine and arginine. Diets were isocaloric and were administered for 3 days. Hepatic plasma membrane vesicles were prepared from rat liver and from human wedge biopsies obtained at laparotomy. The transport of glutamine and arginine by rat and human vesicles was assayed. Vesicle integrity and functionality were verified by osmolarity plots, enzyme marker enrichments, and time courses. Provision of both a standard enteral liquid diet and one enriched with glutamine and arginine increased the activities of Systems N (glutamine) and y+ (arginine) in rat and human liver compared to a control diet. The diet supplemented with glutamine and arginine was the most effective in increasing transport activity. We conclude that the liver responds to diets enriched with specific amino acids by increasing membrane transport activity. This adaptive response provides essential precursors for hepatocytes which may enhance hepatic synthetic functions during catabolic states. This study provides insights into the mechanisms by which enteral nutrition regulates nutrient transport at the cellular level and may provide a biochemical rationale for the use of formulas which are enriched with conditionally essential nutrients.

A role for tumor necrosis factor-alpha in the increased mortality associated with Vibrio vulnificus infection in the presence of hepatic dysfunction

OBJECTIVE

The present study was designed to evaluate whether pre-existing hepatic dysfunction (cirrhosis) leads to increased morbidity and mortality, in part through an inappropriate in vivo tumor necrosis factor-alpha response.

SUMMARY BACKGROUND DATA

Vibrio vulnificus is the most commonly isolated member of the noncholera Vibrio sp., responsible for fulminant and frequently fatal septicemia. A strong clinical association exists between hepatic dysfunction and increased morbidity and mortality from Vibrio sp. infection. However, the underlying mechanism behind this association has not been fully delineated.

METHODS

Cirrhosis was induced in C57BL/6 (15 to 20 g) mice using thrice-weekly injections of carbon tetrachloride (CCl4) for 7 weeks. Either a 7.0 to 9.5 X 10(7) (low dose) or a 0.8 to 1.2 X 10(9) colony-forming unit (high dose) of V. vulnificus was administered through a mini-laparotomy incision via transgastric puncture into both cirrhotic and control animals.

RESULTS

Mortality in cirrhotic mice to low- and high-dose Vibrio infection was 88% (7/8) and 100% (8/8), respectively, whereas mortality in control animals was 0% (0/8) and 12% (1/8), respectively (p<0.01). Tumor necrosis factor-alpha mRNA could be detected by reverse transcriptase polymerase chain reaction in livers and lungs from infected animals 2 and 4 hours after Vibrio administration in both control and cirrhotic animals. Lung and liver tumor necrosis factor-alpha bioactivity, however, was significantly lower in cirrhotic animals infected with Vibrio when compared with controls. Serum tumor necrosis factor-alpha was only sporadically detected in both groups of Vibrio-infected animals. When cirrhotic mice challenged with a low dose of Vibrio sp. were pretreated with 1.0 mg/kg body weight of a novel tumor necrosis factor-alpha receptor immunoadhesin, the increased mortality was completely prevented.

CONCLUSIONS

Cirrhotic mice show increased mortality to Vibrio infection, and this increased mortality is dependent on an in vivo tumor necrosis factor-alpha response.

PEG-BP-30 monotherapy attenuates the cytokine-mediated inflammatory cascade in baboon Escherichia coli septic shock

Septic shock following gram-negative infection is a leading cause of mortality in critically ill patients, accounting for nearly 200,000 deaths a year. The exaggerated production of tumor necrosis factor-alpha (TNF alpha) is known to contribute to hemodynamic collapse and the hematological dyscrasia associated with gram-negative sepsis. Although previous studies have shown TNF alpha antibodies and TNF immunoadhesins to be effective in experimental gram-negative sepsis, we postulated that administration of a novel construct of two modified soluble p55 receptors linked to polyethylene glycol (PEG-BP-30) would also attenuate the hemodynamic and hematologic alterations to lethal Escherichia coli septic shock in non-human primates. Nine adult female and male baboons (Papio anubis), weighing 10-17 kg, were anesthetized and invasively monitored. The nine animals were randomized to receive either 0.2 mg/kg body wt PEG-BP-30 (n = 3), 5.0 mg/kg body wt PEG-BP-30 (n = 3), or placebo (n = 3). One hour after pretreatment, animals were infused with 5-10 x 10(10) CFU/kg of live E. coli iv and vital signs were recorded for the next 8 hr. Arterial blood was drawn for baseline parameters and throughout the study to obtain total and differential white blood cell and platelet counts and cytokine levels (TNF alpha, IL-1 beta, IL-6, IL-8). E. coli bacteremic baboons receiving only placebo demonstrated a significant fall in mean blood pressure and leukopenia. Two of the three animals expired. In contrast, five of the six baboons receiving the PEG-BP-30 survived and these animals exhibited markedly attenuated declines in blood pressure and leukocyte numbers.(ABSTRACT TRUNCATED AT 250 WORDS)

Human tumor necrosis factor receptor (p55) and interleukin 10 gene transfer in the mouse reduces mortality to lethal endotoxemia and also attenuates local inflammatory responses

Anticytokine therapies have been promulgated in gram-negative sepsis as a means of preventing or neutralizing excessive production of proinflammatory cytokines. However, systemic administration of cytokine inhibitors is an inefficient means of targeting excessive production in individual tissue compartments. In the present study, human gene transfer was used to deliver to organs of the reticuloendothelial system antagonists that either inhibit tumor necrosis factor-alpha (TNF-alpha) synthesis or block its interactions with cellular receptors. Mice were treated intraperitoneally with cationic liposomes containing 200 micrograms of either a pCMV (cytomegalovirus)/p55 expression plasmid that contains the extracellular domain and transmembrane region of the human p55 TNF receptor, or a pcD-SR-alpha/hIL-10 expression plasmid containing the DNA for human interleukin 10. 48 h later, mice were challenged with lipopolysaccharide (LPS) and D-galactosamine. Pretreatment of mice with p55 or IL-10 cDNA-liposome complexes improved survival (p < 0.01) to LPS-D-galactosamine. In additional studies, intratracheal administration of IL-10 DNA-liposome complexes 48 h before an intratracheal LPS challenge reduced pulmonary TNF-alpha levels by 62% and decreased neutrophil infiltration in the lung by 55% as measured by myeloperoxidase activity (both p < 0.05). Gene transfer with cytokine inhibitors is a promising option for the treatment of both the systemic and local sequelae of septic shock.

Vasoactive intestinal peptide and substance P receptor antagonists improve postoperative ileus

Octreotide, a somatostatin analogue that inhibits the release of most gut peptides, hastens the resolution of experimental postoperative ileus, suggesting that gut peptides mediate this process. We studied the role of two gut peptides involved in the control of normal gut motility, vasoactive intestinal peptide (VIP), and substance P (SP), in the initiation and maintenance of postoperative small bowel ileus in rats by preoperative administration of VIP and SP receptor antagonists, (VIP-ra and SP-ra). Thirty male Sprague-Dawley rats (300-350 g) underwent laparotomy. One half underwent placement of a duodenal catheter for transit studies while the other half had serosal electrodes placed on the proximal jejunum for myoelectric recordings. Six days later, animals were separated into three treatment groups of five each. Control animals were pretreated with ip saline, while the others received either VIP-ra or SP-ra prior to standardized laparotomy. Following abdominal closure, [Na51]CrO4 was injected into the duodenum and the animals were sacrificed 25 min later. The small bowel was then excised and divided into 10 equal segments. Small bowel transit was calculated as the geometric center of [Na51]CrO4 distribution. The interval until the return of migrating myoelectric complexes (MMCs) was determined in animals with intestinal electrodes. VIP-ra-treated rats demonstrated a 67% improvement in the geometric center of radiolabel relative to controls and SP-ra-treated rats had a 23% improvement (3.67 +/- 0.06 VIP-ra vs 2.69 +/- 0.09 SP-ra vs 2.20 +/- 0.09 control, P < 0.01). MMCs returned 180 +/- 17 min in controls vs 99 +/- 14 min in VIP-ra-treated rats (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Cytokine-mediated alterations in host metabolism prevent nutritional repletion in cachectic cancer patients

The clinical syndrome of cachexia is characterized by anorexia, continued losses of lean body mass, and altered carbohydrate and lipid metabolism. As early as the 1930s, this "chronic wasting" syndrome had been identified as the most frequent immediate cause of death in patients with cancer [Warren: Am J Med Sci 184:610-619, 1932]. At present, controversy remains as to the benefit of supplemental parenteral or enteral feedings in the nutritional repletion of cachectic cancer patients, since only selected patient groups have demonstrated clear benefit from their administration [Copeland et al.: Cancer 43:2108-2116, 1979; Copeland et al.: Cancer Res 37:2451-2456, 1977; Terepka and Waterhouse: Am J Med 20:225-238, 1956]. Despite having these advanced nutritional modalities firmly in our therapeutic armamentarium, the progression of cachexia in the nutritionally depleted cancer patient often continues unabated, and our ability to intervene successfully remains limited. This review proposes that host: tumor interactions lead to a nonspecific inflammatory response mediated in part by the chronic production and release of proinflammatory cytokines, including interleukin-1, tumor necrosis factor alpha, interleukin-6 and interferon-gamma, which antagonize the anabolic signals associated with enteral and parenteral nutrition support. Cytokine-mediated alterations can explain the inability of adequate dietary nitrogen and calories to result in lean tissue repletion. Based on this proposal, interrupting proinflammatory cytokine production or target organ action may be an appropriate therapeutic objective to improve nutrient utilization in patients with tumors.

Normalization of tumor-induced increases in hepatic amino acid transport after surgical resection

BACKGROUND

The liver of the host with cancer requires increased amounts of amino acids to support the synthesis of glucose and key defense proteins. To study the effect of the growing tumor on hepatic amino acid uptake, the authors measured hepatic transport activity in tumor-bearing rats and in rats at various times after tumor resection.

METHODS

Fischer-344 rats were implanted subcutaneously with methylcholanthrene-induced fibrosarcoma cells (MCA sarcoma). When the tumors reached 10% of body weight, hepatic amino acid transport activity was assayed or the animals underwent surgical removal of the tumor. In animals that underwent tumor excision, livers were removed at 1, 3, or 5 days post-resection, and hepatic plasma membrane vesicles (HPMVs) were prepared. Nontumor-bearing pair-fed rats undergoing sham implantation or sham resection served as controls. System N (glutamine), System A (MeAIB), and System y+ (arginine) transport activity were assayed, which allowed the authors to compare differences in tumor-induced rates of transport and the influence of resection on transport activity.

RESULTS

System A transport activity was unaltered by tumor growth. In contrast, the presence of the growing tumor increased arginine and glutamine uptake by the liver. Hepatic glutamine transport remained elevated for 5 days after tumor resection, although by postoperative day 5 there was a trend toward normalization. In contrast, arginine transport remained increased by twofold onpost-resection day 1 and had normalized by postoperative day 3. The enhanced arginine transport was a result of an increase in maximal transport velocity (Vmax) rather than a change in carrier affinity.

CONCLUSIONS

Increases in hepatic amino acid transport normalize within several days of tumor resection, indicating a key role for the tumor in the induction of this response. The observation that hepatic glutamine transport activity remains augmented after tumor resection longer than any other transporter studied suggests a key role for this amino acid in overall hepatic nitrogen metabolism and may partially explain the persistent glutamine depletion that is characteristic of the tumor-bearing host.

Tumor necrosis factor and cachexia: a current perspective

Anorexia, net proteolysis of skeletal muscle and consumption of body fat are hallmarks of the cachexia syndrome associated with chronic disease states. While inanition contributes to cachexia, this wasting diathesis has little in common with simple starvation. The cachexia syndrome is characterized by progressive weight loss and depletion of lean body mass in excess to that resulting from comparable caloric restriction. Accelerated mobilization and consumption of host protein stores from peripheral tissues occurs to support gluconeogenesis and acute phase protein synthesis [1, 2]. In contrast, simple starvation is associated with a relative sparing of lean tissue with the preferential consumption of fat. While the clinical manifestations of cachexia are readily apparent, identification of the specific mechanisms responsible for the development of cachexia remains an enigma. In recent years, interest has focused on the role that the immune system plays in the development of cachexia. Investigators initially hypothesized that the chronic production of two inflammatory cytokines, tumour necrosis factor alpha (TNF alpha) and/or interleukin-1 (IL-1), could explain the host non-specific responses resulting in cachexia [3-5]. Other pro-inflammatory cytokines, including interleukin-6 (IL-6) [6, 7] and interferon-gamma [8, 9], have been more recently proposed to be involved in this complex process. Although no consensus exists for the exclusive role of any one cytokine in the pathogenesis of cachexia, there is growing acceptance that the progression of cachexia results in part from the inappropriate release of one or more pro-inflammatory cytokines [10, 11]. In the present review, the current role of TNF alpha as a mediator of cachexia is examined.

Accelerated hepatic arginine transport in the tumor-bearing rat

BACKGROUND

Arginine plays a pivotal role in regulating ureagenesis, polyamine biosynthesis, and nitric oxide production, metabolic pathways that may be stimulated in the liver of the tumor-bearing host. Normally, plasma arginine is excluded from the hepatocyte intracellular space by the low basal activity of its membrane transporter. We hypothesized that progressive malignant disease is associated with an increase in carrier-mediated arginine transport across the hepatocyte plasma membrane.

METHODS

Twenty-four adult Fischer 344 rats were implanted subcutaneously with fibrosarcomas (TBR) and were studied when the tumors were small [10 +/- 1% of body weight (BW)], medium-sized (15 +/- 1% of BW), and large (25 +/- 1% of BW). Groups of control rats (n = 24) were pair-fed to match carcass weights of the three TBR groups. Livers were excised, and hepatocyte plasma membrane vesicles (HPMVs) were prepared by Percoll density gradient centrifugation. Arginine transport by HPMVs was assayed by a rapid mixing/filtration technique. Vesicle purity and functionality were assessed by membrane enzyme marker enrichments and transportability into an osmotically active space.

RESULTS

Arginine uptake by HPMVs was mediated by both saturable carrier-mediated (System y+) and nonsaturable (diffusion) components. The time course of arginine uptake in HPMVs in the three groups showed similar equilibrium transport rates, indicating similar vesicle sizes. The presence of the growing tumor resulted in a 40-120% increase in System y(+)-mediated arginine transport in HPMVs. This response was dependent on tumor size and was due to a stimulation of carrier Vmax, suggesting an increase in the number of functional System y+ carriers in the hepatocyte plasma membrane. The Na(+)-dependent transport of the System A analog MeAIB was also increased, but only in rats with large tumors.

CONCLUSIONS

Tumor growth results in a progressive increase in hepatic arginine transport, a response mediated primarily by an increase in the activity of System y+. This accelerated transport may amplify the availability of arginine to support key arginine-dependent metabolic pathways in the hepatocyte.

Harry M. Vars Research Award. Influence of fasting on glutamine transport in rat liver

During starvation, the liver switches from an organ of net glutamine uptake to an organ of net glutamine release to help maintain blood glutamine levels. We hypothesized that this shift in hepatic glutamine exchange was regulated at the level of the hepatocyte plasma membrane by adaptive changes in glutamine transport. To test this hypothesis, adult rats (200 g) were allowed to consume regular rat food ad libitum (fed, n = 8) or were fasted for 72 hours (fasted, n = 8, access to water allowed). Livers were excised and hepatocyte plasma membrane vesicles were prepared by differential and Percoll density gradient centrifugation. Vesicle purity and functionality were assessed by marker enzyme measurements, classic "overshoots," and time courses, which showed similar vesicle size. Uptake of 3H-glutamine by hepatocyte plasma membrane vesicles in the presence and absence of sodium was assayed by a rapid mixing/filtration method, which reflects actual transport across the hepatocyte cell membrane in vivo. Fasted rats lost 15 +/- 2% of body weight; fed rats gained weight. Na(+)-dependent glutamine transport (system "N," mediates uptake into the hepatocyte) fell by 22% in the starved group, indicating a diminished rate of glutamine transport into the hepatocyte. In contrast, carrier-mediated Na(+)-independent glutamine transport (system "n," mediates the release of glutamine out of the cell) doubled in the starved animals. Diffusion of glutamine across the vesicle membrane was unchanged by starvation.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of total parenteral nutrition on amino acid and glucose transport by the human small intestine

OBJECTIVE

The effect of total parenteral nutrition (TPN) on small intestinal amino acid transport activity was studied in humans.

SUMMARY BACKGROUND DATA

Studies in humans receiving TPN indicate that a decrease in the activities of the dissacharidase enzymes occurs, but morphologic changes are minimal with only a slight decrease in villous height.

METHODS

Surgical patients were randomized to receive TPN (n = 6) or a regular oral diet (controls, n = 7) for 1 week before abdominal surgery. Ileum (5 controls, 5 TPN) or jejunum (2 controls, 1 TPN) were obtained intraoperatively and brush-border membrane vesicles (BBMV) were prepared by magnesium aggregation/differential centrifugation. Transport of L-MeAlB (a selective system A substrate), L-glutamine, L-alanine, L-arginine, L-leucine, and D-glucose was assayed by a rapid mixing/filtration technique in the presence and absence of sodium.

RESULTS

Vesicles demonstrated approximately 18-fold enrichments of enzyme markers, classic overshoots, transport into an osmotically active space, and similar 1-hour equilibrium values. TPN resulted in a 26-44% decrease in the carrier-mediated transport velocity of all substrates except glutamine across ileal BBMVs. In the one patient receiving TPN from whom jejunum was obtained, there was also a generalized decrease in nutrient transport, although glutamine was least affected. Kinetic studies of the system A transporter demonstrated that the decrease in uptake was secondary to a reduction in carrier Vmax, consistent with a decrease in the number of functional carriers in the brush-border membrane.

CONCLUSIONS

TPN results in a decrease in brush-border amino acid and glucose transport activity. The observation that glutamine transport is not downregulated by 1 week of bowel rest may further emphasize the important metabolic role that glutamine plays as a gut fuel and in the body's response to catabolic stresses.

Influence of progressive tumor growth on glutamine metabolism in skeletal muscle and kidney

OBJECTIVE

The effects of progressive malignant growth on glutamine metabolism in skeletal muscle and in kidney were investigated.

SUMMARY BACKGROUND DATA

Fast-growing tumors consume considerable quantities of glutamine and lead to a decrease in circulating glutamine concentrations.

METHODS

Experiments were performed at various stages of tumor growth in rats implanted subcutaneously with the non-metastasizing methylcholanthrene-induced (MCA) fibrosarcoma and in pair-fed non tumor-bearing controls.

RESULTS

Tumor growth stimulated a twofold increase in hindquarter (muscle) glutamine release, which was not due to an increase in blood flow, but rather to a doubling in the fractional release rate. Consequently, a progressive decrease in skeletal muscle glutamine concentrations was observed over time. Simultaneously, the activity of glutamine synthetase (GS), the principal enzyme of de novo glutamine biosynthesis, increased more than twofold. This increase in muscle GS activity was accompanied by an increase in GS mRNA but the augmentation in GS expression apparently could not match the increased rate of efflux since muscle depletion developed. In rats with large tumors and severe glutamine depletion, GS activity was not elevated. Glutamine feeding increased muscle glutamine concentrations and glutamine synthetase specific activity. Although tumor growth led to the development of mild systemic acidemia, the classic renal adaptations normally observed, i.e., elevated glutaminase activity and accelerated renal glutamine utilization, were not present in acidotic tumor-bearing rats. Instead, renal GS activity was increased in tumor-bearing animals and ammoniagenesis was enhanced, in spite of a reduction in net renal glutamine uptake.

CONCLUSIONS

These data suggest that marked alterations in muscle and renal glutamine handling occur in the host with cancer; the enhanced muscle glutamine release in conjunction with no increase in renal consumption is consistent with increased glutamine uptake in other organs, most likely the tumor itself and the liver.

Na(+)-dependent glutamine transport in the liver of tumour-bearing rats

In rats with advanced malignant disease, the liver extracted circulating glutamine at a ratio three times faster than the liver of control non-tumour-bearing animals. This augmented uptake occurred in spite of a fall in circulating glutamine levels, implying an increase in hepatocyte plasma membrane transport. Na(+)-dependent glutamine transport activity (System N) was increased nearly two-fold in hepatocyte plasma membrane vesicles from tumour-bearing rats; this increase in System N activity was proportional to tumour size and was due to an increase in carrier Vmax with no change in carrier affinity. Measurement of System N activity in isolated hepatocytes incubated with serum from tumour-bearing rats demonstrated a significant increase in glutamine transport compared with cells incubated with serum from control rats. These data indicate that the liver of rats with advanced malignant disease displays accelerated glutamine consumption. This increased uptake is due, in part, to enhanced carrier-mediated transport activity, and is mediated by a circulating factor(s) that is not present (or inactive) in non-tumour-bearing controls.