Steven T. F. Chan

The measurement of liver blood flow: a review of experimental and clinical methods

Changes in hepatic blood flow reflect adaptive responses of the liver to injury, regeneration, and the development of disease states. The measurement of hepatic blood flow is, however, technically challenging and although theoretically useful has not become routine in clinical work. The different techniques that have been developed for quantitative measurement of hepatic blood flow require careful interpretation of the results obtained but are frequently applied without careful considerations of their technical limitations. In particular, many noninvasive techniques depend on good hepatocellular function and are thus irrelevant under most clinical conditions. Many other potentially useful techniques are poorly validated and standardized and there is a need for further research into smethodology. This review summarizes the salient technical features of the different techniques for quantitative measurement of hepatic blood flow. The techniques are divided into invasive, minimally invasive, and noninvasive categories and the relevance of each technique to both routine clinical application or research is discussed.

Loss of cell-surface receptor EphB2 is important for the growth, migration, and invasiveness of a colon cancer cell line

PurposeIn normal colonic epithelium, the receptor tyrosine kinase, EphB2 interacts with ephrinB1 ligand to maintain the integrity and architecture of the colonic crypt. Loss of EphB2 is seen in most colorectal cancers and correlates with poor prognosis. In this study, we investigated the effects of two levels of EphB2 expression on cell migration and invasion in a colon cancer cell line and on the growth of tumour xenografts.MethodsAn EphB2-negative colon cancer cell line (LIM2405) was transfected with a full-length EphB2 cDNA in a vector designed to respond to the drug tetracycline. The effect of two levels of EphB2 expression on the ability of cells to migrate through a porous barrier in response to a chemo-attractant and to invade through artificial basement membranes was tested in vitro. Finally, the effects of two expression levels of EphB2 on tumour growth using an in vivo model of colonic tumour xenograft in a mouse model were assessed.ResultsExpression of moderate levels of EphB2 significantly reduced the migration of tumour cells compared to control (p < 0.05, Kruskal–Wallis test). Expression of high levels of EphB2 further reduced migration of tumour cells (p < 0.05, Kruskal–Wallis test). Similarly, expression of EphB2 markedly reduces the invasive ability of tumour cells. The in vivo model of tumour growth showed that tumours with the highest level of EphB2 expression had a reduced risk of reaching a 10-mm size (defined event) compared with the control group (Cox regression, hazard ratio (HR) = 0.052, 95% CI 0.005–0.550; p = 0.014). Tumours derived from EphB2 expressing cells had a significantly reduced number of mitotic figures (p < 0.05) and an increased number of apoptotic cells (p < 0.05) compared to tumours from control cells.ConclusionEven a moderate level of EphB2 expression has effects on tumour cells which results in reduced migration and invasiveness and slows the growth of colonic tumour implants in an in vivo model.

Recalibration and validation of a preoperative risk prediction model for mortality in major colorectal surgery.

BACKGROUND: In 2009, Barwon Health designed a risk stratification model for mortality in major colorectal surgery with the use of only preoperative risk factors. The Barwon Health 2009 model was shown to predict mortality reliably, and it was comparable to other models, such as the original, POSSUM. However, the Barwon Health 2009 model was never validated with data other than those used to develop the model. OBJECTIVE: The aim of this study was to perform temporal and external validation of the Barwon Health 2009 model and to compare it with other published models. DESIGN: The temporal validation was a prospective observational study, whereas the external validation was a retrospective observational study. The discrimination and calibration of the models were assessed by using the area under receiver operator characteristic and &khgr;2 test of Hosmer-Lemeshow goodness-of-fi technique. SETTINGS: This is a multi-institutional study. Data were collected from 2008 to 2010. RESULTS: There were 474 major colorectal cases at Geelong Hospital (temporal validation) and 389 cases at Western Hospital (external validation). The overall mortality rate was 5.10% and 1.03%. In the comparison of the 2 demographics, Geelong Hospital had a higher proportion of patients who were older and had higher ASA scores and comorbidity counts, whereas Western Hospital surgeons were operating on a higher number of urgent cases. Despite the differences, the Barwon Health 2009 model was able to discriminate mortality reliably (area under receiver operator characteristic = 0.753) but had poor model calibration (p < 0.001) on temporal validation. Hence, the model was recalibrated to predict mortality accurately(area under receiver operator characteristic = 0.772; p = 0.83), and this was successfully validated at Western Hospital (area under receiver operator characteristic = 0.788; p = 0.24). CONCLUSIONS: We have developed a model that can accurately predict mortality after major colorectal surgery by using only data that are available preoperatively. After recalibration, the model was successfully validated in a second hospital.

The 'four-hour target' and the impact on Australian metropolitan acute surgical services.

The National Emergency Access Targets (NEAT), introduced in 2012, guides the clearance of emergency department (ED) presentations within 4 h of initial presentation. We aim to assess the impact of NEAT on acute surgical services at a large metropolitan centre.

Laparoscopy and peritoneal cytology: important prognostic tools to guide treatment selection in gastric adenocarcinoma

Previous studies have suggested that patients with occult peritoneal metastases not seen on preoperative imaging have poor prognosis. In this study, we aim to evaluate the utility and impact of staging laparoscopy and peritoneal cytology in patients with gastric adenocarcinoma.

Colorectal preOperative Surgical Score (CrOSS) for mortality in major colorectal surgery

Colorectal surgery carries a significant mortality risk, with reported rates of 1–6% for elective surgery and up to 22% in the emergency setting. Both clinicians and patients will benefit from being able to predict the likelihood of death before surgery. Recently, we have described and validated two risk stratification models for colorectal surgery, the Barwon Health 2012 and Association Française de Chirurgie models. However, these models are not suitable for assessment at patients bedside. The purpose of this study is to develop a simplified preoperative model capable of predicting mortality following colorectal surgery.

Ward safety checklist in the acute surgical unit

Deficiencies in daily ward rounds are increasingly identified. A ward safety checklist has recently been devised to improve the fast‐paced surgical ward round.

The infusion method trial of void vs standard catheter removal in the outpatient setting: a prospective randomized trial.

• To ascertain if filling the bladder with warm normal saline before trial of void (TOV) reduces time to decision of outcome of TOV and time to discharge compared with standard in‐dwelling catheter (IDC) removal in the outpatient setting.

Urinary catheter balloons should only be filled with water: testing the myth

To test the hypothesis that urinary catheter balloons filled with sterile water, saline or glycine have equivalent rates of failure to deflate.

Predictive factors for publication of abstracts at the Royal Australasian College of Surgeons Annual Scientific Congress

A key metric of the research quality of medical conferences is the publication rate of abstracts. The study objective was to determine the publication rate of abstracts presented at the Royal Australasian College of Surgeons Annual Scientific Congress (RACS ASC) and to examine for any predictive factors associated with publication.