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G Atkin

Publications and source records attributed to G Atkin.

10 recordsLinked to original sources
PubMed2006

The effect of surgically induced ischaemia on gene expression in a colorectal cancer xenograft model.

Delays in tissue fixation following tumour vascular clamping and extirpation may adversely affect subsequent protein and mRNA analysis. This study investigated the effect of surgically induced ischaemia in a xenograft model of a colorectal cancer on the expression of a range of prognostic, predictive, and hypoxic markers, with a particular emphasis on thymidylate synthase. Vascular occlusion of human tumour xenografts by D-shaped metal clamps permitted defined periods of tumour ischaemia. Alterations in protein expression were measured by immunohistochemistry and spectral imaging, and changes in mRNA were measured by reverse transcriptase-polymerase chain reaction. Thymidylate synthase expression decreased following vascular occlusion, and this correlated with cyclin A expression. A similar reduction in dihydropyrimidine dehydrogenase was also seen. There were significant changes in the expression of several hypoxic markers, with carbonic anhydrase-9 showing the greatest response. Gene transcriptional levels were also noted to change following tumour clamping. In this xenograft model, surgically induced tumour ischaemia considerably altered the gene expression profiles of several prognostic and hypoxic markers, suggesting that the degree of tumour ischaemia should be minimised prior to tissue fixation.

Animals↗
PubMed2006

Dynamic contrast-enhanced magnetic resonance imaging is a poor measure of rectal cancer angiogenesis.

BACKGROUND: The aim of this study was to investigate the use of magnetic resonance imaging (MRI) for non-invasive measurement of rectal cancer angiogenesis and hypoxia. METHODS: Fifteen patients with rectal adenocarcinoma underwent preoperative dynamic contrast-enhanced (DCE) and blood oxygenation level-dependent (BOLD) MRI. Microvessel density (CD31 level), and expression of vascular endothelial growth factor (VEGF) and carbonic anhydrase (CA) 9 were measured immunohistochemically in histological tumour sections from 12 patients. Serum VEGF levels were also measured in 14 patients. Correlations between quantitative imaging indices and immunohistochemical variables were examined. RESULTS: There was good correlation between circulating VEGF and CD31 expression (r(S) = 0.88, P < 0.001). CD31 expression did not correlate with any dynamic MRI parameter, except transfer constant, with which it correlated inversely (r(S) = -0.65, P = 0.022). Tissue and circulating VEGF levels did not correlate, and neither correlated with any tumour DCE MRI parameter. No relationship was seen between BOLD MRI and CA-9 expression. CONCLUSION: The negative correlation between transfer constant (reflecting tumour blood flow and microvessel permeability) with CD31 expression is paradoxical. DCE MRI methods for assessing tissue vascularity correlate poorly with histological markers of angiogenesis and hypoxia, suggesting that DCE MRI does not simply reflect static histological vascular properties in patients with rectal cancer.

Adenocarcinoma↗
PubMed2002

Bilateral sensorineural hearing loss complicating basal skull fracture.

Otological damage is well-recognized following head injury. The commonest complication is hearing loss. We present a case of bilateral sensorineural hearing loss due to bilateral temporal bone fractures following an epileptic seizure, which is unique in the literature and illustrates the importance of this complication of head injury.

Adult↗
PubMed1998

The role of compositionality in standardized problem list generation.

Compositionality is the ability of a Vocabulary System to record non-atomic strings. In this manuscript we define the types of composition, which can occur. We will then propose methods for both server based and client-based composition. We will differentiate the terms Pre-Coordination, Post-Coordination, and User-Directed Coordination. A simple grammar for the recording of terms with concept level identification will be presented, with examples from the Unified Medical Language System's (UMLS) Metathesaurus. We present an implementation of a Window's NT based client application and a remote Internet Based Vocabulary Server, which makes use of this method of compositionality. Finally we will suggest a research agenda which we believe is necessary to move forward toward a more complete understanding of compositionality. This work has the promise of paving the way toward a robust and complete Problem List Entry Tool.

Humans↗
PubMed1989

[Effects of surface demineralization on fracture healing in rat tibias].

Surface demineralization of bone in vivo induces new cartilage and bone formation locally. We studied the effects of local surface demineralization of the tibia in the rat on the process of fracture healing. We found that demineralization for 20 minutes with 0.5N HCl induced in the first 10 days following fracture less cartilaginous callus, with less calcium and magnesium, as compared to controls. However, from the second week on, the amount of cartilaginous callus in HCl-treated and control fractured bones was similar. Bony callus was greater in HCl-treated bones throughout the experiment, but X-rays showed poor bone union 5-8 weeks following fracture. Surface demineralization of bone in vitro induces local cartilage and bone formation, but inhibits good fracture healing.

Animals↗