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R Negus

Publications and source records attributed to R Negus.

10 recordsLinked to original sources
PubMed2005

Magnetic resonance colonography versus colonoscopy as a diagnostic investigation for colorectal cancer: a meta-analysis.

AIMS: Magnetic resonance colonography (MRC) is emerging as a potential complementary investigation for the diagnosis of colorectal cancer (CRC) and also for benign pathology such as diverticular disease. A meta-analysis reporting the use of MRC is yet to be performed. The aim of this study was to evaluate the diagnostic accuracy of MRC compared with the gold-standard investigation, conventional colonoscopy (CC). METHODS: A literature search was carried out to identify studies containing comparative data between MRC findings and CC findings. Quantitative meta-analysis for diagnostic tests was performed, which included the calculation of independent sensitivities, specificities, diagnostic odds ratios, the construction of summary receiver operating characteristic (SROC) curves, pooled analysis and sensitivity analysis. The study heterogeneity was evaluated by the Q-test using a random-effect model to accommodate the cluster of outcomes between individual studies. RESULTS: In all, 8 comparative studies were identified, involving 563 patients. The calculated pooled sensitivity for all lesions was 75% (95% CI: 47% to 91%), the specificity was 96% (95% CI: 86% to 98%) and the area under the ROC curve was 90% (weighted). On sensitivity analysis, MRC had a better diagnostic accuracy for CRC than for polyps, with a sensitivity of 91% (95% CI: 97% to 91%), a specificity of 98% (95% CI: 66% to 99%) and an area under the ROC curve of 92%. There was no significant heterogeneity between the studies with regard to the diagnostic accuracy of MRC for CRC. CONCLUSION: This meta-analysis suggests that MRC is an imaging technique with high discrimination for cases presenting with colorectal cancer. The exact diagnostic role of MRC needs to be clarified (e.g. suitable for an elderly person with suspected CRC). Further evaluation is necessary to refine its applicability and diagnostic accuracy in comparison with other imaging methods such as computed tomography colonography.

Adenocarcinoma↗
PubMed1999

Hypoxia inhibits macrophage migration.

The chemokine monocyte chemoattractant protein (MCP)-1 plays a role in regulating the lymphocyte and macrophage infiltrate in ovarian cancer, but macrophages also accumulate in necrotic areas of the tumors where there is little MCP-1 expression (Negus, R. P. M. et al., Am. J. Pathol. 1997. 150: 1723-1734). Necrotic regions are likely to be hypoxic. In this study we show that hypoxia inhibits MCP-1-induced migration of THP-1 monocytic cells and human macrophages. In contrast, lymphocytes from peripheral blood migrate normally to an MCP-1 gradient in hypoxic conditions. The inhibition of monocyte migration by hypoxia is rapid and reversible. At the exposure times studied (30-90 min) hypoxia does not affect expression of the MCP-1 receptor CCR2B and cells exposed to hypoxia still respond to MCP-1 with an elevation of intracellular calcium. Although hypoxia is known to modulate gene expression, the inhibition of migration reported here was not due to the production of soluble factors, and mRNA expression of macrophage migration inhibitory factor was unchanged. Hypoxia-induced inhibition of chemotaxis was not limited to MCP-1. Hypoxia also inhibited the chemotactic response to macrophage inflammatory protein-1alpha, RANTES and the chemoattractant N-formyl-met-leu-phe, but hypoxic cells were still able to phagocytose opsonized red blood cells. We suggest that inhibition of migration by hypoxia is not due to gene regulation but is a reflection of metabolic changes in the cell. Transient hypoxia may regulate the distribution of macrophages in tumors and other inflammatory conditions.

Cell Hypoxia↗
PubMed1996

A cytokine profile of normal and malignant ovary.

We defined a cytokine mRNA profile of 12 ovarian cancer biopsies, 10 normal/benign biopsies, six ovarian cancer cell lines and three ovarian cancer xenografts, using RT-PCR. The profile, based on screening for 25 cytokines and 12 receptor mRNAs, was rich in growth factors, pro-inflammatory cytokines and chemokines, but weak in lymphocyte-associated cytokines. The pattern was unique to ovarian tissue, but similar in normal, benign and malignant biopsies, with > 80% samples expressing 16 cytokines in common. Fourteen of these were also expressed by > 65% cell lines, but fewer were detected in xenografts. Potential autocrine loops existed for IL-1, IGF-1, M-CSF, GM-CSF and TNF-alpha. IL-4 and IFN-gamma receptors were expressed in absence of ligand. Chemokines RANTES, MIP-1 alpha and MIP-1 beta were expressed in biopsies, but were rarely detected in cell lines and absent from xenografts. IGF-1 and its receptor was expressed in every sample, as was IFN-gamma receptor. Another 10 cytokine mRNAs and six receptors were expressed in > 80% samples. These may contribute to key survival/growth loops. Similarities between normal and malignant biopsies suggest that analogous processes of remodelling and repair occur. RT-PCR proved a rapid, reproducible screen, but further assays are required to detect quantitative differences between normal and malignant tissues and tumour models.

Animals↗
PubMed1995

Magnetic resonance angiography of renal artery stenosis.

Renal artery stenosis is a common cause of renal impairment which in many cases may be potentially reversible. The diagnosis and follow-up of this condition is commonly carried out using the relatively invasive technique of intra-arterial angiography. Magnetic resonance angiography (MRA) is emerging as a possible alternative technique to conventional angiography. We have studied 60 patients who were referred for investigation of possible renal artery stenosis using both 3-D phase contrast MRA techniques and conventional digital arteriography. Studies were assessed prospectively and conventional angiography was assumed to be the gold standard for the purposes of this study. Calculated sensitivity and specificity results were 84% and 91% respectively, for 3-D phase contrast MRA of the renal arteries. We conclude that 3-D phase contrast MRA is a very promising technique for the noninvasive investigation of renal artery stenosis with high sensitivity and specificity levels acting as a screening test in the future for patients with this potential diagnosis, diminishing the amount of conventional angiograms that are performed.

Adult↗
PubMed1994

Case report: extrathoracic herniation of the lung with a review of the literature.

A case of extrathoracic herniation of the lung is described together with the radiological findings in this condition including the role of computed tomography (CT) in its management. In addition a review of the literature is presented which outlines the incidence, classification and clinical features of lung herniae. Some reference is made to possible methods of treatment.

Hernia↗
PubMed1992

Magnetic resonance angiography of renal transplants.

Stenosis of the artery of transplanted kidneys is an important cause of graft dysfunction. Diagnosis and follow-up of this condition normally requires intra-arterial digital-subtraction angiography (IADSA), which is invasive and may cause complications. A possible alternative to IADSA is magnetic resonance angiography (MRA), and we have assessed this technique in 50 renal transplant patients who were referred for investigation of possible renal arterial stenosis. In every patient, MRA was compared prospectively with conventional IADSA. Compared with IADSA, MRA had a sensitivity of 83% and a specificity of 97%, and when all images were graded retrospectively for severity of stenosis, the two techniques showed a significant correlation (r = 0.74, p less than 0.001). MRA can provide an accurate image of the renal transplant artery in a non-invasive manner with a high sensitivity and specificity.

Angiography, Digital Subtraction↗
PubMed1991

Renal transplant vein stenosis: demonstration and percutaneous venoplasty of a new vascular complication in the transplant kidney.

Stenosis of the renal transplant vein has been demonstrated in eight patients undergoing investigation for renal dysfunction arising 3 weeks to 3 years after transplantation. The stenoses were diagnosed by duplex Doppler ultrasound in three cases and by angiography in the presence of arterio-venous fistula in five cases. In four patients percutaneous venous dilatation was performed with technical success in three. In two patients this was repeated for recurrent stenosis but sustained improvement in renal function was not observed. Progression of the venous stenoses was documented with one patient suffering graft loss due to complete venous occlusion.

Adult↗