Daniel Schiller

Hepatitis C virus replication in mice with chimeric human livers

Lack of a small animal model of the human hepatitis C virus (HCV) has impeded development of antiviral therapies against this epidemic infection. By transplanting normal human hepatocytes into SCID mice carrying a plasminogen activator transgene (Alb-uPA), we generated mice with chimeric human livers. Homozygosity of Alb-uPA was associated with significantly higher levels of human hepatocyte engraftment, and these mice developed prolonged HCV infections with high viral titers after inoculation with infected human serum. Initial increases in total viral load were up to 1950-fold, with replication confirmed by detection of negative-strand viral RNA in transplanted livers. HCV viral proteins were localized to human hepatocyte nodules, and infection was serially passaged through three generations of mice confirming both synthesis and release of infectious viral particles. These chimeric mice represent the first murine model suitable for studying the human hepatitis C virus in vivo.

Treatment of gastric cancer with peritoneal carcinomatosis by cytoreductive surgery and HIPEC: A systematic review of survival, mortality, and morbidity

Gastric cancer with peritoneal carcinomatosis has an extremely poor prognosis, which may be improved with cytoreductive surgery (CRS) combined with heated intraperitoneal chemotherapy (HIPEC). We systematically reviewed the literature regarding the efficacy of CRS + HIPEC in these patients. Electronic databases were searched from 2000 to 2010. Following CRS + HIPEC, overall median survival was 7.9 months and improved to 15 months for patients with completeness of cytoreduction scores of 0/1, however with a 30‐day mortality rate of 4.8%. J. Surg. Oncol. 2011; 104:692–698.

Anti-HCV therapies in chimeric scid-Alb/uPA mice parallel outcomes in human clinical application†

Compounds with in vitro anti‐hepatitis C virus (HCV) activity are often advanced directly into clinical trials with limited or no in vivo efficacy data. This limits prediction of clinical efficacy of compounds in the HCV drug pipeline, and may expose human subjects to unnecessary treatment effects. The scid‐Alb‐uPA mouse supports proliferation of transplanted human hepatocytes and subsequent HCV infection. Cohorts of genotype 1a HCV‐infected mice were treated with interferon α‐2b(IFN‐α), BILN‐2061 (anti‐NS3 protease), or HCV371 (anti‐NS5B polymerase). Mice treated with 1350IU/g/day IFN‐α intramuscularly for 10 to 28 days demonstrated reduced viral titers compared with controls in all five experiments (P < .05, t test); viral titers rebounded after treatment withdrawal. A more pronounced antiviral effect with IFN‐α was seen in genotype 3a–infected mice. Pilot studies with BILN2061 confirmed exposure to 10X replicon EC50 at trough and reduced viral titer over 2 log at 4 days. In a second 7‐day study, mean HCV RNA titers dropped 1.1 log in BILN2061‐treated animals, 0.6 log in IFN‐treated mice, and rose 0.2 log in controls (P = .013, ANOVA). Pre‐existing mutants with partial resistance to BILN2061 were identified by sequencing both the human inoculum and sera from treated mice. The polymerase inhibitor HCV371 yielded a decline in HCV titers of 0.3 log relative to vehicle‐treated controls (P = NS). Performance of all three antiviral regimens in the chimeric mouse model paralleled responses in humans. In conclusion, this system may help selection of lead compounds for advancement into human trials with an increased likelihood of clinical success while broadening the tools available for study of the biology of HCV infection. (HEPATOLOGY 2006;43:1346–1353.)

Metabolomics and surgical oncology: Potential role for small molecule biomarkers

Metabolomics, the newest of the “omics” sciences, has brought much excitement to the field of oncology as a potential new translational tool capable of bringing the molecular world of cancer care to the bedside. While still early in its development, metabolomics could alter the scope and role of surgery in the multidisciplinary treatment of cancer. This review examines potential roles of metabolomics in areas of early cancer detection, personalized therapeutics and tumorigenesis. J. Surg. Oncol. 2011; 103:451–459.

Urinary metabolomic signature of esophageal cancer and Barrett’s esophagus

BackgroundEsophageal adenocarcinoma (EAC) often presents at a late, incurable stage, and mortality has increased substantially, due to an increase in incidence of EAC arising out of Barrett’s esophagus. When diagnosed early, however, the combination of surgery and adjuvant therapies is associated with high cure rates. Metabolomics provides a means for non- invasive screening of early tumor-associated perturbations in cellular metabolism.MethodsUrine samples from patients with esophageal carcinoma (n = 44), Barrett’s esophagus (n = 31), and healthy controls (n = 75) were examined using 1H-NMR spectroscopy. Targeted profiling of spectra using Chenomx software permitted quantification of 66 distinct metabolites. Unsupervised (principal component analysis) and supervised (orthogonal partial least-squares discriminant analysis OPLS-DA) multivariate pattern recognition techniques were applied to discriminate between samples using SIMCA-P+ software. Model specificity was also confirmed through comparison with a pancreatic cancer cohort (n = 32).ResultsClear distinctions between esophageal cancer, Barrett’s esophagus and healthy controls were noted when OPLS-DA was applied. Model validity was confirmed using two established methods of internal validation, cross-validation and response permutation. Sensitivity and specificity of the multivariate OPLS-DA models were summarized using a receiver operating characteristic curve analysis and revealed excellent predictive power (area under the curve = 0.9810 and 0.9627 for esophageal cancer and Barrett’s esophagus, respectively). The metabolite expression profiles of esophageal cancer and pancreatic cancer were also clearly distinguishable with an area under the receiver operating characteristics curve (AUROC) = 0.8954.ConclusionsUrinary metabolomics identified discrete metabolic signatures that clearly distinguished both Barrett’s esophagus and esophageal cancer from controls. The metabolite expression profile of esophageal cancer was also discrete from its precursor lesion, Barrett’s esophagus. The cancer-specific nature of this profile was confirmed through comparison with pancreatic cancer. These preliminary results suggest that urinary metabolomics may have a future potential role in non-invasive screening in these conditions.

The script concordance test as a measure of clinical reasoning: a national validation study

INTRODUCTION The script concordance test (SCT) is an innovative tool for clinical reasoning assessment. It has previously been shown to be a reliable and valid measure of clinical reasoning among general surgical residents. PURPOSE To determine if the SCT maintained its validity and reliability when administered on a national level. METHODS The test was administered to 202 residents (51 R1, 45 R2, 45 R3, 28 R4, and 33 R5) in 9 general surgery programs across Canada. RESULTS The optimized version of the test had a reliability (Cronbach alpha) of .85. Scores increased progressively from R1 (64.5 ± 7.6) to R2 (69.5 ± 5.8) to R3 (69.9 ± 6.7) to R4 (72.0 ± 6.2) with a dip in the R5s (68.3 ± 8.6). The test was able to differentiate junior (R1+ R2 = 66.8 ± 7.2) from senior residents (R3 + R4 + R5 = 70.0 ± 7.3, P = .001) across all the programs. CONCLUSIONS The SCT maintained its reliability and validity as a measure of intraoperative clinical reasoning among general surgical residents when administered across multiple centers. We believe that the SCT can be developed to measure clinical reasoning in high-stakes national examinations.

1 H-NMR urinary metabolomic profiling for diagnosis of gastric cancer

Background:Metabolomics has shown promise in gastric cancer (GC) detection. This research sought to identify whether GC has a unique urinary metabolomic profile compared with benign gastric disease (BN) and healthy (HE) patients.Methods:Urine from 43 GC, 40 BN, and 40 matched HE patients was analysed using 1H nuclear magnetic resonance (1H-NMR) spectroscopy, generating 77 reproducible metabolites (QC-RSD <25%). Univariate and multivariate (MVA) statistics were employed. A parsimonious biomarker profile of GC vs HE was investigated using LASSO regularised logistic regression (LASSO-LR). Model performance was assessed using Receiver Operating Characteristic (ROC) curves.Results:GC displayed a clear discriminatory biomarker profile; the BN profile overlapped with GC and HE. LASSO-LR identified three discriminatory metabolites: 2-hydroxyisobutyrate, 3-indoxylsulfate, and alanine, which produced a discriminatory model with an area under the ROC of 0.95.Conclusions:GC patients have a distinct urinary metabolite profile. This study shows clinical potential for metabolic profiling for early GC diagnosis.

The clinical significance of incidental intra-abdominal findings on positron emission tomography performed to investigate pulmonary nodules

BackgroundLung cancer is a common cause of cancer-related death. Staging typically includes positron emission tomography (PET) scanning, in which18F-fluoro-2-dexoy-D-glucose (FDG) is taken up by cells proportional to metabolic activity, thus aiding in differentiating benign and malignant pulmonary nodules. Uptake of FDG can also occur in the abdomen. The clinical significance of incidental intraabdominal FDG uptake in the setting of pulmonary nodules is not well established. Our objective was to report on the clinical significance of incidental intra-abdominal FDG activity in the setting of lung cancer.MethodsFifteen hundred FDG-PET reports for studies performed for lung cancer were retrospectively reviewed for the presence of incidental FDG-positive intraabdominal findings. Patient charts with positive findings were then reviewed and information extracted.ResultsTwenty-five patients (25/1500) demonstrated incidental intraabdominal FDG uptake thought to be significant (1.7%) with a mean patient age of 71 years. Colonic uptake was most common (n = 17) with 9 (52%) being investigated further. Of these 9 cases, a diagnosis of malignancy was made in 3 patients, pre-malignant adenomas in 2 patients, a benign lipoma in 1 patient and no abnormal findings in the remaining patients. 8 patients were not investigated further (3 diagnosed with metastatic lung cancer and 2 were of advanced age) secondary to poor prognosis.ConclusionIncidental abdominal findings in the colon on FDG-PET scan for work-up of pulmonary nodules need to be further investigated by colonoscopy.

Hepatic Resection for Colorectal Liver Metastases and the Role of Positron Emission Tomography Imaging

Colorectal cancer remains the third most prevalent cancer worldwide, contributing to over 600,000 deaths per year. In North America, colorectal cancer is the fourth most common newly diagnosed cancer each year. Colorectal cancer often metastasizes to the liver, which is best treated with a combination of surgical hepatic resection and chemotherapy. Unfortunately, only 20% of patients are candidates for surgical resection at presentation. Accurately determining resectability of hepatic metastatic disease is important prior to proceeding to surgery. The optimal imaging modality remains to be determined. Computed tomography (CT) and magnetic resonance imaging (MRI) have been the primary imaging modalities used to date to identify intrahepatic metastatic disease. Positron emission tomography (PET) imaging has been shown to increase sensitivity and specificity for detecting extrahepatic metastases. However, PET imaging is limited by the inability to accurately localize these lesions. Combined PET/CT imaging has been proposed as method to improve accuracy in detecting intra and extra-hepatic metastases. Current evidence is limited and further prospective studies are needed to clarify the role of PET/CT imaging in metastatic colorectal disease.