Robert Ramsay - Academia.edu (original) (raw)

Papers by Robert Ramsay

Annals of Surgical Oncology

Background Pre-clinical studies indicate that dry-cold-carbon-dioxide (DC-CO2) insufflation leads... more Background Pre-clinical studies indicate that dry-cold-carbon-dioxide (DC-CO2) insufflation leads to more peritoneal damage, inflammation and hypothermia compared with humidified-warm-CO2 (HW-CO2). Peritoneum and core temperature in patients undergoing colorectal cancer (CRC) surgery were compared. Methods Sixty-six patients were randomized into laparoscopic groups; those insufflated with DC-CO2 or HW-CO2. A separate group of nineteen patients undergoing laparotomy were randomised to conventional surgery or with the insertion of a device delivering HW-CO2. Temperatures were monitored and peritoneal biopsies and bloods were taken at the start of surgery, at 1 and 3 h. Further bloods were taken depending upon hospital length-of-stay (LOS). Peritoneal samples were subjected to scanning electron microscopy to evaluate mesothelial damage. Results Laparoscopic cases experienced a temperature drop despite Bair-HuggerTM use. HW-CO2 restored normothermia (≥ 36.5 °C) by 3 h, DC-CO2 did not. L...

Annals of Surgical Oncology, 2015

Background. Conventional laparoscopic surgery uses CO 2 that is dry and cold, which can damage pe... more Background. Conventional laparoscopic surgery uses CO 2 that is dry and cold, which can damage peritoneal surfaces. It is speculated that disseminated cancer cells may adhere to such damaged peritoneum and metastasize. We hypothesized that insufflation using humidified-warm CO 2 , which has been shown to reduce mesothelial damage, will also ameliorate peritoneal inflammation and tumor cell implantation compared to conventional dry-cold CO 2. Methods. Laparoscopic insufflation was modeled in mice along with anesthesia and ventilation. Entry and exit ports were introduced to maintain insufflation using dry-cold or humidified-warm CO 2 with a constant flow and pressure for 1 h; then 1000 or 1 million fluorescent-tagged murine colorectal cancer cells (CT26) were delivered into the peritoneal cavity. The peritoneum was collected at intervals up to 10 days after the procedure to measure inflammation, mesothelial damage, and tumor burden using fluorescent detection, immunohistochemistry, and scanning electron microscopy.

Cell Death & Disease, 2013

The gastrointestinal (GI) epithelium is constantly renewing, depending upon the intestinal stem c... more The gastrointestinal (GI) epithelium is constantly renewing, depending upon the intestinal stem cells (ISC) regulated by a spectrum of transcription factors (TFs), including Myb. We noted previously in mice with a p300 mutation (plt6) within the Myb-interaction-domain phenocopied Myb hypomorphic mutant mice with regard to thrombopoiesis, and here, changes in GI homeostasis. p300 is a transcriptional coactivator for many TFs, most prominently cyclic-AMP response element-binding protein (CREB), and also Myb. Studies have highlighted the importance of CREB in proliferation and radiosensitivity, but not in the GI. This prompted us to directly investigate the p300-Myb-CREB axis in the GI. Here, the role of CREB has been defined by generating GI-specific inducible creb knockout (KO) mice. KO mice show efficient and specific deletion of CREB, with no evident compensation by CREM and ATF1. Despite complete KO, only modest effects on proliferation, radiosensitivity and differentiation in the GI under homeostatic or stress conditions were evident, even though CREB target gene pcna (proliferating cell nuclear antigen) was downregulated. creb and p300 mutant lines show increased goblet cells, whereas a reduction in enteroendocrine cells was apparent only in the p300 line, further resembling the Myb hypomorphs. When propagated in vitro, crebKO ISC were defective in organoid formation, suggesting that the GI stroma compensates for CREB loss in vivo, unlike in MybKO studies. Thus, it appears that p300 regulates GI differentiation primarily through Myb, rather than CREB. Finally, active pCREB is elevated in colorectal cancer (CRC) cells and adenomas, and is required for the expression of drug transporter, MRP2, associated with resistance to Oxaliplatin as well as several chromatin cohesion protein that are relevant to CRC therapy. These data raise the prospect that CREB may have a role in GI malignancy as it does in other cancer types, but unlike Myb, is not critical for GI homeostasis.

British Journal of Cancer

Colorectal peritoneal metastases (CRPM) can be resistant to the chemotherapy agent (oxaliplatin) ... more Colorectal peritoneal metastases (CRPM) can be resistant to the chemotherapy agent (oxaliplatin) most employed, up until recently, as hyperthermic intraperitoneal chemotherapy (HIPEC). Glutathione-mediated inactivation of oxaliplatin can be substantially reduced by genomic deletion of the gene or pharmacological inhibition of glutamate-cysteine ligase in CRPM tumouroids. These discoveries may rekindle the enthusiasm for HIPEC in concert with cytoreductive surgery, which has been employed to manage patients with this once-nihilistic form of stage-IV disease.

MYB oncogene upregulation is associated with estrogen receptor (ER)-positive breast cancer, but d... more MYB oncogene upregulation is associated with estrogen receptor (ER)-positive breast cancer, but disease requirements for MYB function in vivo have not been explored. In this study, we provide evidence of a critical requirement forMYB functions inmodels of human andmurine breast cancer. In human breast cancer, we found thatMYB expression was critical for tumor cell growth both in vitro and in vivo in xenograft settings. In transgenic knockout mice, tissue-specific deletion of the murine MYB gene caused a transient defect in mammary gland development that was reflected in delayed ductal branching and defective apical bud formation. In mouse mammary tumor virus (MMTV)-NEUmice where tumors are initiated by activation of HER2, MYB deletion was sufficient to abolish tumor formation. In the more aggressive MMTV-PyMTmodel system,MYB deletion delayed tumorigenesis significantly. Together, the findings in these transgenic knockout models implied that MYB was critical during an early window in...

Background: The exposure of the peritoneum to desiccation during surgery generates lasting damage... more Background: The exposure of the peritoneum to desiccation during surgery generates lasting damage to the mesothelial lining which impacts inflammation and tissue repair. We have previously explored open abdominal surgery in mice subjected to passive airflow however, operating theatres employ active airflow. Therefore, we sought an engineering solution to recapitulate the active airflow in mice. Similarly, to the passive airflow studies we investigated the influence of humidified-warm carbon dioxide (CO2) on this damage in the context of active airflow. Additionally, we addressed the controversial role of surgery in exacerbating desmoidogenesis in a mouse model of familial adenomatous polyposis. Methods: An active airflow mouse-operating module manufactured to produce the equivalent downdraft airflow to that of a modern operating theatre was employed. We quantified mesothelial cell integrity by scanning electron microscopy (SEM) sampled from the peritoneal wall that was subjected to ...

Molecular cancer research : MCR, 2004

Hypersensitivity to chemo- and radiotherapy employed during cancer treatment complicates patient ... more Hypersensitivity to chemo- and radiotherapy employed during cancer treatment complicates patient management. Identifying mutations in genes that compromise tissue recovery would rationalize treatment and may spare hypersensitive patients undue tissue damage. Genes that govern stem cell homeostasis, survival, and progenitor cell maintenance are of particular interest in this regard. We used wild-type and c-myb knock-out mice as model systems to explore stem and progenitor cell numbers and sensitivity to cytotoxic damage in two radiosensitive tissue compartments, the bone marrow and colon. Because c-myb null mice are not viable, we used c-myb heterozygous mice to test for defects in stem-progenitor cell pool recovery following gamma-radiation and 5-fluorouracil treatment, showing that c-myb(+/-) mice are hypersensitive to both agents. While apoptosis is comparable in mutant and wild-type mice following radiation exposure, the crypt beds of c-myb(+/-) mice are markedly depleted of prol...

c-myb is expressed in human and murine colonic mucosa and elevated expression occurs in premalign... more c-myb is expressed in human and murine colonic mucosa and elevated expression occurs in premalignant adenomatous polyps and carcinomas. c-Myb is required for colon cell proliferation, and there is evidence of c-myb down-regulation during differentiation. Recently, c-myb has been implicated in hematopoietic cell survival via regulation of bcl-2 gene expression. However, c-myb expression during terminal differentiation and apoptosis in the colonic crypt has not been examined. The experiments in this study examine the spatial and temporal expression of c-Myb protein in vivo using human colonic crypt sections and in vitro in human colon tumor cell lines undergoing butyrate-induced differentiation and apoptosis. Electron microscopy, together with molecular and biochemical analysis, was used to define the differentiation status of the cells. Results demonstrate a decrease in c-Myb expression during the commitment of cells to differentiation and apoptosis. Decreased levels of c-Myb are acc...

Annals of Surgical Oncology

Michael Flood, MRCS , Vignesh Narasimhan, PhD, Kasmira Wilson, FRACS, Wei Mou Lim, FRACS, Robert ... more Michael Flood, MRCS , Vignesh Narasimhan, PhD, Kasmira Wilson, FRACS, Wei Mou Lim, FRACS, Robert Ramsay, PhD, Michael Michael, MD, and Alexander Heriot, MD Department of Surgical Oncology, Peter MacCallum Cancer Centre, Melbourne, Australia; Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, Australia; Department of Medical Oncology, Peter MacCallum Cancer Centre, Melbourne, Australia

Clinical & Translational Immunology

Tumor‐infiltrating lymphocytes (TIL), particularly CD8+ TILs in patients with colorectal cancer (... more Tumor‐infiltrating lymphocytes (TIL), particularly CD8+ TILs in patients with colorectal cancer (CRC), are highly prognostic in the early‐disease stages (I‐II). In metastatic disease (stage IV; mCRC), their influence is less well defined. It has presumably failed to contain tumor cells to the primary site; however, is this evident? We explored the prognostic impact of TILs at the primary site in patients who presented de novo with mCRC.

Surgical Endoscopy

Background Insufflation with CO 2 can employ continuous flow, recirculated gas and/or additional ... more Background Insufflation with CO 2 can employ continuous flow, recirculated gas and/or additional warming and humidification. The ability to compare these modes of delivery depends upon the assays employed and opportunities to minimize subject variation. The use of pigs to train colorectal surgeons provided an opportunity to compare three modes of CO 2 delivery under controlled circumstances. Methods Sixteen pigs were subjected to rectal resection, insufflated with dry-cold CO 2 (DC-CO 2) (n = 5), recirculated CO 2 by an AirSeal device (n = 5) and humidification and warming (HW-CO2) by a HumiGard device (n = 6). Peritoneal biopsies were harvested from the same region of the peritoneum for fixation for immunohistochemistry for hypoxia-inducible factor 1 alpha (HIF-1α) and scanning electron microscopy (SEM) to evaluate hypoxia induction or tissue/cellular damage, respectively. Results DC-CO 2 insufflation by both modes leads to significant damage to mesothelial cells as measured by cellular bulging and retraction as well as microvillus shortening compared with HW-CO 2 at 1 to 1.5 h. DC-CO 2 also leads to a rapid and significant induction of HIF-1α compared with HW-CO 2. Conclusions DC-CO 2 insufflation induces substantive cellular damage and hypoxia responses within the first hour of application. The use of HW-CO 2 insufflation ameliorates these processes for the first one to one and half hours in a large mammal used to replicate surgery in humans.

ANZ Journal of Surgery

Diverticulosis and redundant colon are colonic conditions for which underlying pathophysiology, m... more Diverticulosis and redundant colon are colonic conditions for which underlying pathophysiology, management and prevention are poorly understood. Historical papers suggest an inverse relationship of these two conditions. However, no further attempt has been made to validate this relationship. This study set out to assess the correlation between diverticulosis and colonic redundancy. Methodology: The presence of redundant colon and diverticulosis were noted during colonoscopy. Multivariate binary logistic regression was performed with the aim of developing a probability nomogram. Multivariate logistic regression was performed with redundant colon as the dependent variable and diverticulosis, age and gender as independent variables. Nagelkerke R2 and a receiver operator curve with area under curve were calculated to assess goodness of fit and internally validate the multivariate model. Results: The probability of redundant colon was increased by female gender odds ratio (OR) 8.4 (95% CI 2.7-26, p=0.00020) and increasing age OR 1.7 (95% CI 1.1-2.6, p=0.017). Paradoxically, diverticulosis strongly reduced the probability of redundant colon with OR of 0.12 (95% CI 0.42-0.32, p=0.000039). The Nagelkerke R2 for the multivariate model was 0.29 and area under the curve at ROC analysis was 0.81 (CI 95% 0.73-0.90 pvalue 3.1x10-8). Conclusions: This study found an inverse correlation between redundant colon and diverticulosis, supporting the historical suggestion that the two conditions rarely occur concurrently. The underlying principle for this relationship remains to be found. However, it may contribute to the understanding of the aetiology and pathophysiology of these colonic conditions.

PLoS ONE, 2013

The colony stimulating factor-1 (CSF-1) receptor (CSF-1R) directly regulates the development of P... more The colony stimulating factor-1 (CSF-1) receptor (CSF-1R) directly regulates the development of Paneth cells (PC) and influences proliferation and cell fate in the small intestine (SI). In the present study, we have examined the role of CSF-1 and the CSF-1R in the large intestine, which lacks PC, in the steady state and in response to acute inflammation induced by dextran sulfate sodium (DSS). As previously shown in mouse, immunohistochemical (IHC) analysis of CSF-1R expression showed that the receptor is baso-laterally expressed on epithelial cells of human colonic crypts, indicating that this expression pattern is shared between species. Colons from Csf1r null and Csf1 op/op mice were isolated and sectioned for IHC identification of enterocytes, enteroendocrine cells, goblet cells and proliferating cells. Both Csf1r 2/2 and Csf1 op/op mice were found to have colon defects in enterocytes and enteroendocrine cell fate, with excessive goblet cell staining and reduced cell proliferation. In addition, the gene expression profiles of the cell cycle genes, cyclinD1, c-myc, c-fos, and c-myb were suppressed in Csf1r 2/2 colonic crypt, compared with those of WT mice and the expression of the stem cell marker gene Lgr5 was markedly reduced. However, analysis of the proliferative responses of immortalized mouse colon epithelial cells (lines; Immorto-5 and YAMC) indicated that CSF-1R is not a major regulator of colonocyte proliferation and that its effects on proliferation are indirect. In an examination of the acute inflammatory response, Csf1r +/2 male mice were protected from the adverse affects of DSS-induced colitis compared with WT mice, while Csf1r +/2 female mice were significantly less protected. These data indicate that CSF-1R signaling plays an important role in colon homeostasis and stem cell gene expression but that the receptor exacerbates the response to inflammatory challenge in male mice.

Oncogene, 2015

Transcription factor Myb is overexpressed in most colorectal cancers (CRC). Patients with CRC exp... more Transcription factor Myb is overexpressed in most colorectal cancers (CRC). Patients with CRC expressing the highest Myb are more likely to relapse. We previously showed that mono-allelic loss of Myb in an Adenomatous polyposis coli (APC)-driven CRC mouse model (Apc Min/+) significantly improves survival. Here we directly investigated the association of Myb with poor prognosis and how Myb cooperates with tumor suppressor genes (TSGs) (Apc) and cell cycle regulator, p27. Here we generated the first intestinalspecific, inducible transgenic model; a MybER transgene encoding a tamoxifen-inducible fusion protein between Myb and the estrogen receptor-α ligand-binding domain driven by the intestinal-specific promoter, Gpa33. This was to mimic human CRC with constitutive Myb activity in a highly tractable mouse model. We confirmed that the transgene was faithfully expressed and inducible in intestinal stem cells (ISCs) before embarking on carcinogenesis studies. Activation of the MybER did not change colon homeostasis unless one p27 allele was lost. We then established that MybER activation during CRC initiation using a pro-carcinogen treatment, azoxymethane (AOM), augmented most measured aspects of ISC gene expression and function and accelerated tumorigenesis in mice. CRC-associated symptoms of patients including intestinal bleeding and anaemia were faithfully mimicked in AOM-treated MybER transgenic mice and implicated hypoxia and vessel leakage identifying an additional pathogenic role for Myb. Collectively, the results suggest that Myb expands the ISC pool within which CRC is initiated while cooperating with TSG loss. Myb further exacerbates CRC pathology partly explaining why high MYB is a predictor of worse patient outcome.

Annals of Surgical Oncology

Langenbeck's Archives of Surgery

Annals of Surgical Oncology

Annals of Surgical Oncology, 2015

Cell Death & Disease, 2013

British Journal of Cancer

Molecular cancer research : MCR, 2004

Annals of Surgical Oncology

Clinical & Translational Immunology

Surgical Endoscopy

ANZ Journal of Surgery

PLoS ONE, 2013

Oncogene, 2015

Annals of Surgical Oncology

Langenbeck's Archives of Surgery