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Biomedical subjects

P Revell

Publications and source records attributed to P Revell.

At least 19 recordsLinked to original sources
PubMed2005

Techniques and trouble-shooting in high spatial resolution thin slice MRI for rectal cancer.

MRI is increasingly advocated as an optimal method of staging rectal cancer. The technique enables depiction of the relationship of tumour to the mesorectal fascia and may thus identify tumours at risk of positive circumferential margin involvement at surgery. Depth of extramural spread may also be accurately measured and tumour deposits within the mesorectum are shown. It is important that a high spatial resolution technique is used in order to accurately depict these features and care should be taken in ensuring that images acquired cover the entire rectal tumour and mesorectum. This paper describes the technique of high spatial resolution rectal cancer imaging and the potential technical pitfalls in acquiring good quality images. Important factors to consider include: adequate scan duration to achieve high spatial resolution images with sufficient signal to noise ratio, careful positioning of the pelvic phased array coil, use of T2 weighted turbo spin-echo rather than T1 weighted imaging and careful planning of scans to ensure that images are obtained perpendicular to the rectal wall.

Humans↗
PubMed2003

Transfusion for anaemia in the district hospital setting.

We examined the practice of transfusion for anaemia in our hospitals using an audit method, with standards derived from guidelines published by the British Committee for Standards in Haematology. Documentation was generally good, but simple tests were not performed prior to transfusion in many cases when the diagnosis was not known.

Anemia↗
PubMed2000

Symptomatic brachial plexopathy following treatment for breast cancer: utility of MR imaging with surface-coil techniques.

PURPOSE: To investigate the clinical utility and diagnostic accuracy of magnetic resonance (MR) imaging in patients with symptomatic brachial plexopathy following treatment for breast cancer. MATERIALS AND METHODS: Fifty patients with symptoms of brachial plexopathy (principally pain, weakness, and paresthesia) who had received treatment for breast cancer, which included surgery, radiation therapy, and cytotoxic chemotherapy, underwent MR imaging at 1.5 T. MR imaging was performed by using a body coil, which was supplemented with surface-coil imaging of the cervical spine and shoulder-coil imaging of the brachial plexus. At review, two observers attempted to discriminate between tumor recurrence and nonmalignant causes of symptoms. The diagnosis was verified with histologic analysis or a follow-up of at least 12 months. RESULTS: Of 27 patients demonstrated to have tumor recurrence, 26 were correctly identified by using MR imaging; the recurrence was directly related to the brachial plexus in 17. During the follow-up, 21 patients remained free of recurrence, 20 of whom were determined to have a nonmalignant cause of symptoms. Two of the 50 patients were excluded from the analysis. The MR criteria used for detection of tumor yielded a sensitivity of 96%, specificity of 95%, positive predictive value of 96%, and negative predictive value of 95%. CONCLUSION: MR imaging is reliable and accurate in the diagnosis of symptomatic brachial plexopathy following breast cancer therapy.

Adult↗
PubMed1998

Magnetic resonance imaging of prostate cancer: comparison of image quality using endorectal and pelvic phased array coils.

OBJECTIVE: To compare endorectal coil (ERC) and pelvic phased array (PPA) coil magnetic resonance imaging for delineation of the prostate gland and seminal vesicles. To compare ERC images at different inflation volumes of the ERC air balloon. MATERIALS AND METHODS: Twenty-one patients underwent T2-weighted examinations using PPA and ERC. The ERC evaluations were performed at three balloon inflation volumes (60, 100 and 140 ml). All patients had proven prostate cancer. Images were analysed for visibility of anatomic structures, gland distortion, tumour visualization, artefacts (coil flare, coil-related artefact and rectal movement) and overall image quality. A grading system was used for each parameter. RESULTS: ERC assessments at increasing balloon inflations showed equivalent anatomical detail and overall image quality. However, increasing gland distortion and decreasing coil related flare was found with higher air inflations (P = 0.13 and P = 0.006, respectively). When compared with ERC images, visibility of the anterior gland and neurovascular bundles was better with the PPA coil (P = 0.0001 and 0.002, respectively). The overall image quality was superior with the PPA coil (P = 0.0001). However, no significant difference in visualization of tumour or delineation of tumour extent was observed between the two techniques. CONCLUSIONS: PPA imaging of the prostate gland provides images of superior quality compared with the ERC. This is mainly due to fewer artefacts with the PPA coil and improved anterior gland visibility. When ERC is used, air inflation to at least 100 ml reduces coil flare artefact.

Aged↗
PubMed1998

Skin irritation potential of mixed surfactant systems.

Virtually all current detergent formulations contain mixtures of surfactants. Our experience and test data on these formulations, which is in agreement with that of many others, has shown that in use the formulations exhibit lower acute irritation potential than predicted by simple summation of the irritation potential of the individual actives. Using the criteria of the Dangerous Preparations Directive (EC Directive 88/379/EEC), many of these formulations classify as irritant in the neat state, with consequent labelling requirements. Such classification is based on addition of irritant components giving a total concentration which exceeds a nominal threshold. In this study, mixtures of surfactants were tested by application to a panel of 31 human volunteers for up to 4 hr, using the technique established for the assessment of acute skin irritation potential. The positive control, sodium dodecyl sulfate (SDS) at 20% concentration, gave an 84% positive response. Dimethyl dodecyl amido betaine (DDAB) at the same concentration gave a 94% response. However, a combination of 20% of each of these surfactants in the same panellists gave a response of only 44%--a significant reduction in the irritation potential. A further test conducted with a mixture of 10% SDS and 10% DDAB in a second panel gave a 31% positive response compared with a 94% positive response to the 20% SDS control in that panel. These results clearly demonstrate that the acute irritation potential of mixed surfactants cannot be predicted by simple summation of the irritation potential of the component substances. Initial results of the mechanistic investigation indicate that the reduced irritation induced by the mixed surfactant systems correlates with a reduced critical micelle concentration (CMC). However, the reduced CMC itself seems not to be responsible for the lowered irritation, since these experiments were conducted at concentrations well above the CMC. It is proposed that the critical event leading to skin irritation is binding to skin protein and that in mixed surfactant systems, the individual surfactants exhibit less affinity for this protein.

Betaine↗
PubMed1995

Platelets in treated adrenoleukodystrophy: a brief report.

Platelet counts have been noted to be low in patients treated with high-oil diet therapy for adrenoleukodystrophy. We suggest that some of these observations are spurious but that others reflect a true thrombocytopenia. Visual platelet counts are recommended.

Adrenoleukodystrophy↗
PubMed1995

Mode of spread to and within the central nervous system after oral infection of neonatal mice with the DA strain of Theiler's murine encephalomyelitis virus.

Theiler's murine encephalomyelitis virus is a neurotropic enterovirus known to cause biphasic neural disease after intracerebral inoculation into adult mice. The present study characterizes a neonatal mouse model with a high disease incidence for the study of the acute phase of the pathogenesis of the DA strain of Theiler's murine encephalomyelitis virus after oral infection. The route of viral spread to and within the central nervous system (CNS) was determined by examining the kinetics of viral replication in various organs and by performing histopathological analysis. Viral antigen was detected widely in the neonatal CNS, mainly in the gray matter, and it was asymmetrical and multifocal in its distribution, with considerable variation in lesion distribution from animal to animal. Necrotizing lesions appeared to expand by direct extension from infected cells to their close neighbors, with a general disregard of neuroanatomical boundaries. The diencephalon showed particular susceptibility to viral infection. Other areas of the CNS, including the cerebellum and dentate gyrus of the hippocampus, were consistently spared. Neurons with axons extending peripherally to other organs or receiving direct input from the peripheral nervous system were not preferentially affected. The kinetics of viral replication in the liver, spleen, and CNS and the histopathological findings indicate that viral entry to the CNS is via a direct hematogenous route in orally infected neonatal mice and that the disease then progresses within the CNS mainly by direct extension from initial foci.

Aging↗
PubMed1992

Experimental studies of the biological response to a new bone cement: II Soft tissue reactions in the rat.

The biological response to a new bone cement (London Hospital cement), which contains polyethylmethacrylate/n-butylmethacrylate, has been examined experimentally and compared with polymethylmethacrylate. The cellular reaction was identical when the polymer powders of the cements were inserted subcutaneously in rats, there being a macrophage response to the polymer beads of both materials. Experimental implantation of the two cements into the paraspinal musculature of rats showed that there was less tissue damage adjacent to the new material than to polyethylmethacrylate. There was a significantly smaller macrophage and giant cell reaction in relation to the polyethylmethacrylate/n-butylmethacrylate cement. These differences may be related to the lower heat of polymerisation of the new cement and to its smoother surface contour, as demonstrated by scanning electron microscopy.

Animals↗
PubMed1991

Hip arthropathy in genetic hemochromatosis. Radiographic and histologic features.

Genetic hemochromatosis, a disorder of iron metabolism, results in the deposition of massive amounts of iron in the tissues. Arthropathy is one of a number of clinical features associated with the disease. Characteristic radiographic features in the wrist and hand have been reported, and an increased incidence of severe hip disease has been observed. In this study, hip radiographs of 112 patients with genetic hemochromatosis and arthritis were reviewed, and histologic examination of 2 femoral heads was performed. Twenty-eight of the 112 patients (25%) had evidence of arthritis of the hip joint. In 23 (82%) of the 28 patients, this feature was thought to be associated with osteoarthritis; 2 of these patients had an atypical arthropathy associated with radiolucency of the femoral head and histologic features of atypical stripping of the cartilage from the subchondral bone. These atypical features were not thought to be due to avascular necrosis, pyrophosphate-associated arthropathy, apatite-associated deposition arthritis, or osteoarthritis, but may be typical of genetic hemochromatosis and possibly the result of increased susceptibility to shearing forces at the bone-cartilage interface. In 5 of the 28 patients (18%), chondrocalcinosis was the sole abnormal finding on radiography. Ten of the 28 patients eventually required hip surgery, which confirms the severity of the hip disease associated with genetic hemochromatosis.

Adult↗
PubMed1991

Folic acid absorption in patients infected with the human immunodeficiency virus.

To determine the folic acid absorption characteristics of patients with human immunodeficiency virus (HIV) infection, a prospective, controlled, result-blind single-dose oral absorption study was conducted. A total of 25 subjects were fasted and given 5 mg oral folic acid; blood samples were taken at time zero and after 30, 60, 90 and 180 min. Absorption of folic acid appears to be significantly impaired in HIV disease, irrespective of the stage of the disease and notwithstanding gastro-intestinal complaints, pathogen-negative diarrhoea or drug treatment. We here present functional data, complementary to previously reported structural and biochemical findings, to support the hypothesis that the virus can cause an enteropathy in the absence of opportunist infection. Folinic acid is absorbed by the same gut mechanism as folic acid, so caution may be needed when employing oral folinic acid rescue procedures in these patients, even when resting serum and red cell folate levels appear to be normal.

Absorption↗
PubMed1991

Bleeding diathesis coincident with chronic myelomonocytic leukaemia.

Two important haematological problems were found in an otherwise healthy 78 year old man: chronic myelomonocytic leukaemia; and a complex, acquired, hyperfibrinolytic bleeding disorder characterized by prolonged coagulation times, deficiency of coagulation factors V, X, and XI, anti-thrombin III and proteins C and S, with high concentrations of circulating tissue plasminogen activator, and low concentrations of plasminogen activator inhibitor. There may be a causal relation between the two conditions, with the peripheral blood monocytes mediating the hyperfibrinolytic process by the abnormal production of tissue plasminogen activator, though no previous description of a similar association has been reported.

Aged↗
PubMed1990

Donor leucocyte imaging in patients with AIDS: a preliminary report.

Four patients with the acquired immunodeficiency syndrome (AIDS) and fever were investigated using donor leucocyte scans. The lung/liver and lung/spleen uptake ratios in these patients were compared with the uptake ratios in donor leucocyte scans in seven neutropenic (non-AIDS) patients and five patients who had autologous leucocyte scans performed over the same time period. For all scans indium-111-oxime-labelled leucocytes were used, except for one AIDS patient in whom technetium-99m hexamethyl-propylene amine oxide (HMPAD)-labelled donor leucocytes were used. There were no adverse reactions to the donor cell infusions. Two patients had repeat studies 8 weeks apart (from different donors) without ill effect. There were no differences in the 111In uptake ratios between the three groups. There were three positive studies in the patients with AIDS, and these elucidated the cause of the pyrexia in all three. The negative case is more difficult to confirm, but the clinical course and the absence of focal disease on post-mortem have been taken to support the scan findings. There was no difference in the acceptability of the technique or the distribution of the labelled leucocytes between the AIDS and non-AIDS patients. Donor leucocyte imaging of patients with AIDS is probably more effective and considerably less hazardous for technical staff than autologous leucocyte methods. This study demonstrates that the technique can be applied successfully to patients with AIDS.

Acquired Immunodeficiency Syndrome↗