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Biomedical subjects

R Allan

Publications and source records attributed to R Allan.

At least 19 recordsLinked to original sources
PubMed2003

Pseudotumour cerebri, CSF rhinorrhoea and the role of venous sinus stenting in treatment.

We present a case of pseudotumour cerebri (PTC), which is important as it illustrates the effects of chronically raised CSF pressure, the relationship between PTC and venous sinus obstruction and the successful treatment of PTC using a venous sinus stent. A 38-year-old woman, previously diagnosed with PTC and unsuccessfully treated 10 years previously re-presented with spontaneous CSF rhinorrhoea. Imaging revealed dramatic changes of chronically raised CSF pressure and a defect in the anterior cranial fossa. The CSF leak was corrected surgically and a lumbo-peritoneal shunt inserted to correct a large postoperative subgaleal CSF collection. Direct retrograde cerebral venography (DRCV) demonstrated venous sinus obstruction due to a filling defect. This was associated with a pressure gradient and a high superior sagittal sinus pressure. The venous sinus obstruction was successfully treated with a venous sinus stent and the lumbo-peritoneal shunt was removed. Chronically raised CSF pressure in untreated cases of PTC may cause widespread changes in the skull, which in this case, culminated in a spontaneous CSF leak despite relatively mild headache and visual symptoms. Furthermore, cases of PTC secondary to venous sinus obstruction may be successfully treated using venous sinus stenting. The index of suspicion for venous sinus stenosis or obstruction should be raised in the investigation of patients with PTC.

Adult↗
PubMed2002

Insecticide-treated plastic tarpaulins for control of malaria vectors in refugee camps.

Spraying of canvas tents with residual pyrethroid insecticide is an established method of malaria vector control in tented refugee camps. In recent years, plastic sheeting (polythene tarpaulins) has replaced canvas as the utilitarian shelter material for displaced populations in complex emergencies. Advances in technology enable polythene sheeting to be impregnated with pyrethroid during manufacture. The efficacy of such material against mosquitoes when erected as shelters under typical refugee camp conditions is unknown. Tests were undertaken with free-flying mosquitoes on entomological study platforms in an Afghan refugee camp to compare the insecticidal efficacy of plastic tarpaulin sprayed with deltamethrin on its inner surface (target dose 30 mg/m2), tarpaulin impregnated with deltamethrin (initially > or = 30 mg/m2) during manufacture, and a tent made from the factory impregnated tarpaulin material. Preliminary tests done in the laboratory with Anopheles stephensi Liston (Diptera: Culicidae) showed that 1-min exposure to factory-impregnated tarpaulins would give 100% mortality even after outdoor weathering in a temperate climate for 12 weeks. Outdoor platform tests with the erected materials (baited with human subjects) produced mosquito mortality rates between 86-100% for sprayed or factory-impregnated tarpaulins and tents (average approximately 40 anophelines and approximately 200 culicines/per platform/night), whereas control mortality (with untreated tarpaulin) was no more than 5%. Fewer than 20% of mosquitoes blood-fed on human subjects under either insecticide-treated or non-treated shelters. The tarpaulin shelter was a poor barrier to host-seeking mosquitoes and treatment with insecticide did not reduce the proportion blood-feeding. Even so, the deployment of insecticide-impregnated tarpaulins in refugee camps, if used by the majority of refugees, has the potential to control malaria by killing high proportions of mosquitoes and so reducing the average life expectancy of vectors (greatly reducing vectorial capacity), rather than by directly protecting refugees from mosquito bites. Mass coverage with deltamethrin-sprayed or impregnated tarpaulins or tents has strong potential for preventing malaria in displaced populations affected by conflict.

Afghanistan↗
PubMed2001

Nonselective versus selective beta-adrenergic receptor blockade in congestive heart failure: differential effects on sympathetic activity.

BACKGROUND: Activation of the sympathetic nervous system has important prognostic implications in chronic heart failure. Nonselective versus selective beta-adrenergic receptor antagonists may have differential effects on norepinephrine release from nerve terminals mediated by prejunctional beta(2)-adrenergic receptors. METHODS AND RESULTS: Thirty-six patients with chronic heart failure were randomized to the nonselective beta-blocker carvedilol or the selective beta-blocker metoprolol (double-blind). Measurements of hemodynamics and cardiac and systemic norepinephrine spillover as well as microneurographic recordings of muscle sympathetic nerve traffic were made before and after 4 months of therapy. In the carvedilol group (n=17), there were significant reductions in both total body (-1.7+/-0.5 nmol/min, P<0.01) and cardiac norepinephrine spillover (-87+/-29 pmol/min, P<0.01). By contrast, in the metoprolol group (n=14), there were no significant changes in total body or cardiac norepinephrine spillover. Responses in the carvedilol group were significantly different from those observed in the metoprolol group (P<0.05). Both agents caused a reduction in heart rate and increases in pulse pressure, although mean arterial pressure did not change. Importantly, microneurographic measures of sympathetic nerve traffic to skeletal muscle did not change in either group. CONCLUSIONS: Therapy with carvedilol caused significant decreases in systemic and cardiac norepinephrine spillover, an indirect measure of norepinephrine release. Such changes were not observed in patients treated with metoprolol. There was no effect of either agent on sympathetic efferent neuronal discharge to skeletal muscle. These findings suggest that carvedilol, a nonselective beta-blocker, caused its sympathoinhibitory effect by blocking peripheral, prejunctional beta-adrenergic receptors.

Adolescent↗
PubMed2001

Barriers to help seeking in people with urinary symptoms.

BACKGROUND: Urinary incontinence is a common problem but, for those experiencing significant clinical symptoms, help seeking has been reported to be as low as 20%. As many of these people could be helped by simple interventions, there is a clear need to identify barriers to help seeking and develop interventions to overcome these barriers. OBJECTIVES: This study explores help-seeking behaviour in people with urinary symptoms such as leakage, frequency, nocturia and urgency in order to identify barriers to service use. METHOD: Thirty-one people who either had agreed to treatment as part of an intervention study or who were receiving treatment at a hospital out-patient clinic for their urinary problems took part in unstructured, taped interviews. Respondents were questioned about their views on help seeking for urinary problems and their personal experiences of consultations. The data were transcribed, coded and thematic analysis carried out. RESULTS: The most common theme to emerge was a lack of knowledge of the condition and of available treatments. Urinary symptoms frequently were considered a normal part of ageing or childbirth, or it was felt that these types of symptoms were inappropriate for medical intervention. Older people were not only more likely to accept symptoms but were also less likely to want to bother their GP. Patients did not always communicate their concerns about urinary symptoms to their GP, through either embarrassment or misconceptions of what is a 'medical problem'. CONCLUSIONS: There is a clear need for health education and health promotion in this area. Future work should explore professionals' knowledge and views of these types of conditions with the aim of providing guidelines for management in primary care.

Adult↗
PubMed2001

Contrast-enhanced helical computerised tomography in the investigation of thoracic aortic injury.

Aortic angiography is widely considered the 'gold standard' for the diagnosis of traumatic thoracic aortic injury. Unfortunately, thoracic aortic angiography has many disadvantages: the technique is invasive but, more importantly, it is not routinely available in all hospitals, necessitating transfer of critically ill patients. Contrast-enhancement helical computerised tomography (CEHCT) of the thorax is rapidly becoming available, especially in more district general hospitals, and has been shown to be as sensitive and specific in detecting aortic trauma as angiography. This technique has the advantage of being non-invasive and is able to demonstrate injuries other than thoracic aortic disruption. We present four cases of traumatic thoracic disruption initially diagnosed using CEHCT in whom surgical repair was performed on the basis of the CEHCT findings. The surgical findings of aortic injury were correlated with CEHCT features.

Accidents, Traffic↗
PubMed2000

Improving the emergency department detection rate of domestic violence using direct questioning.

The purpose of this study was to compare the domestic violence (DV) rate identified with simple direct questioning to a historical cohort of patients receiving routine emergency department (ED) care. One thousand ED charts of female patients were retrospectively reviewed. Each patient in the prospective cohort was asked five DV specific questions. The historical cohort revealed a DV prevalence rate of 0.4%. The prospective study group of 302 patients identified 11 (3.6%) patients who admitted to acute DV on direct questioning. Ten of these patients accepted help. Twenty (6.6%) were identified as probable DV and 12 (4%) admitted to past violence. The total number of victims of DV, past, present, and probable was 43 (14.2%). This increase in detection from 0.4% (4/1000) to 14.2% (43/302) is significant at p < 0.001. Only 1.3% of patients refused to participate in the DV specific questions. The conclusion of the study indicated that the use of simple, direct questioning significantly improves the detection rate of DV in the ED.

Adult↗
PubMed2000

Aberrant sentinel nodes in malignant melanoma.

The option of sentinel lymph node biopsy for patients with a cutaneous malignant melanoma has allowed an alternative to the traditional approaches to lymph node basin surgery. Lymphatic mapping usually identifies the sentinel node(s) in a recognised lymphatic basin, however aberrant nodes may occasionally be identified outside these areas. The notes of 100 consecutive patients with a localised cutaneous malignant melanoma, who had a sentinel lymph node biopsy in our unit, were reviewed. Lymphatic mapping identified three patients with aberrant sentinel lymph nodes. Failure to remove an aberrant sentinel lymph node harbouring metastatic melanoma may reduce significantly the chance of control or cure of the disease. In order to reduce this risk we advocate lymphatic mapping prior to surgical management of the draining lymph nodes of a cutaneous malignant melanoma.

Adult↗
PubMed2000

Sentinel lymph node biopsy in malignant melanoma: a series of 100 consecutive patients.

A consecutive cohort of 100 patients who had undergone sentinel lymph node biopsy (SLNB) was analysed retrospectively. Three areas were studied: success in finding the sentinel node(s); complications of the procedure; and extra costs incurred by SLNB. The sentinel node(s) were successfully identified in 98% of the lymph node basins biopsied. The overall complication rate was 33%. The additional cost of the procedure was estimated at 1420 pounds sterling per patient. SLNB can reliably identify the sentinel node. However there is a significant complication rate of the technique and considerable additional costs. SLNB requires further critical evaluation before it can be accepted as a standard treatment for patients with malignant melanoma.

Adolescent↗
PubMed1999

Impact of an aggressive stenting strategy on initial and one-year follow-up costs in patients undergoing coronary angioplasty.

BACKGROUND: Although stents have been shown in randomised trials to reduce restenosis rates compared with balloon angioplasty, there are concerns regarding the cost-effectiveness of an aggressive stenting strategy. Stents were shown to increase medical costs over 12 months in the early trials. AIM: Our aim was to determine the economic impact of an aggressive stenting strategy using current stenting techniques compared with a conservative stenting strategy. METHODS: Initial and one year follow-up costs were determined in all patients who underwent successful revascularisation during June to December 1996 (aggressive stenting, n = 401), and compared to all patients treated in the corresponding months in 1995 (conservative stenting, n = 347). All patients had clinical follow-up for one year. RESULTS: The proportion of patients receiving a stent increased from 22.5% in 1995 to 66.1% in 1996 (p < 0.0001). Requirement for repeat procedures in the 1995 group compared with 1996 was coronary angiography in 31% vs 16% (p < 0.001), coronary angioplasty in 11% vs 6% (p = 0.0044) and bypass surgery in 4.8% vs 2.5% (p = 0.054). The mean initial cost of the procedure was higher in the aggressive stenting group ($4319 +/- 1276 in 1995 vs $5131 +/- 1491 in 1996, p < 0.0001), but after 12 months follow-up, total medical costs were equivalent ($5975 +/- 4143 in 1995 vs $5994 +/- 3476 in 1996, p = NS). CONCLUSION: An aggressive coronary stenting strategy is associated with higher initial costs compared with a conservative strategy, but lower costs during follow-up due to reduced need for repeat procedures, resulting in equivalent one year total medical costs.

Angioplasty, Balloon, Coronary↗
PubMed1998

Group psychotherapy for patients with coronary heart disease.

Group therapy with cardiac patients is a relatively new specialty. The field is supported by a substantial epidemiological and experimental literature demonstrating links between heart and mind. There are several clinical trials that have demonstrated less morbidity, improved quality of life, and, to some extent, lower mortality for patients who have received psychosocial intervention, generally group therapy, compared to control patients. Different theoretical orientations and a small number of clinical techniques have been developed to help cardiac patients make an adjustment to heart-healthy living. This article provides a brief review of the literature in cardiac psychology, suggestions for developing a psychotherapy practice specialty with cardiac patients, techniques for treating these patients, and conclusions by a psychologist-cardiologist team that has been active in this area for more than a decade.

Coronary Disease↗
PubMed1998

Alterations in classical cadherins associated with progression in ulcerative and Crohn's colitis.

Human colitis is a condition associated with a spectrum of altered morphologic changes and cellular adhesion. The role of cadherins, which are powerful morphoregulatory cell adhesion molecules, in colitis is provocative and as yet unknown. Herein, we present results that suggest a strong correlation between the deregulation of two cadherin molecules, E- and P-cadherins, and the progression of human colitis. We examined the expression and structural integrity of E- and P-cadherins in inflamed, dysplastic, or neoplastic human ulcerative colitis (UC) (n=58), human Crohn's colitis (n = 30), and normal tissue (n = 20) to assess cadherin function in normal and abnormal epithelium. E-cadherin is strongly expressed in normal colorectal epithelium, whereas in left-sided UC it is either down-regulated or has a single-base pair mutation in exon 4 resulting in an amino acid alteration (6 of 58 UC cases). By contrast, P-cadherin is dramatically up-regulated in both Crohn's disease and ulcerative colitis and especially in dysplastic ulcerative tissue. In vitro transfected SW-480 colorectal cells containing E-cadherin mutations identical to those in vivo were associated with increased spontaneous disaggregation compared with cells transfected with wild-type E-cadherin. Based on this evidence, we hypothesize that a small subset of colorectal cells expressing mutant E-cadherin are associated with widespread ulceration, whereas those expressing P-cadherin are associated with a rapidly dividing immature phenotype that includes dysplasia. The differential expression of mutated and wild-type cadherins examined herein are associated with a broad spectrum of abnormal epithelial phenotypes, lymphocyte integrin binding, and resistance to denudation, as is seen in the colitis adenocarcinoma sequence.

Adult↗
PubMed1996

The role of common carotid artery end-diastolic velocity in near total or total internal carotid artery occlusion.

OBJECTIVES: To evaluate the role of the end-diastolic velocity (EDV) in the common carotid artery (CCA) as a marker of internal carotid artery (ICA) occlusion. DESIGN: Validation of retrospective data in a prospective clinical study. METHODS: The EDV in 94 patients with total ICA occlusion and in 24 patients with high grade (95-99%) unilateral ICA stenosis identified on extracranial carotid colour-flow Duplex imaging (CFDI) and arteriography was reviewed, and was retrospectively compared to the EDV of 176 normal individuals. Identification of patients with ICA occlusion was most accurate (99.3%) with an ipsilateral EDV > or = 12 cm/s and a DIFF > or = 10 cm/s (DIFF = contralateral EDV -- ipsilateral EDV). These values were then prospectively applied to all 886 patients (67 with high grade stenosis or occlusion) who underwent CFDI at our institution during 1994. RESULTS: The EDV > or = 12 had a 92% sensitivity, a 99.4% negative predictive value (NPV) and a 85% specificity in distinguishing between occluded and patent ICA's. In combination with a DIFF > or = 10 was 80.4% sensitive and 97.5% specific. The positive predictive value of the EDV > or = 12 in the distinction between 95-99% ICA stenosis and ICA occlusion was 78.3%, and that of the combination was 85.4%. The EDV was rarely zero and 10% of patients with normal or minimally diseased ICA's had an EDV > or = 12 and/or a DIFF > or = 10. CONCLUSIONS: The EDV < or = 12 cm/s is a sensitive marker of ICA occlusion with a high NPV and in combination with the DIFF > or = 10 cm/s, is specific. Nevertheless, EDV parameters are inaccurate in the distinction of 95-99% ICA stenosis from occlusion. Low EDV can be found in a number of patients with minor or no ICA disease, particularly in those with a stroke or silent cerebral infarct.

Adult↗