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Biomedical subjects

E Duvall

Publications and source records attributed to E Duvall.

At least 19 recordsLinked to original sources
PubMed2006

Using a quality control approach to define an 'adequately cellular' liquid-based cervical cytology specimen.

OBJECTIVE: To define a minimum acceptable total squamous cellularity for (ThinPrep) liquid-based cervical cytology (LBC) specimens using quality control techniques. METHODS: Two hundred LBC preparations were made containing varying numbers (<200) of severely dyskaryotic squamous cells and with varying total cellularities. RESULTS: Ninety-eight per cent of the LBC preparations that were missed by one or more of three cytoscreeners had fewer than 16 abnormal objects (single dyskaryotic cells or clumps of cells) and 87 dyskaryotic cells. The minimum ratio of dyskaryotic to total squamous cells that, in a preparation of 5000 squamous cells has a probability of at least 0.98 that 87 or more dyskaryotic cells will be present is 1:47. Twenty-three preparations diagnosed as abnormal had ratios of dyskaryotic to total squamous cells of between 1:2.5 and 1:4596. There is thus no feasible minimum acceptable squamous cellularity that will give an acceptable probability of detection of all specimen vials containing abnormal cells in the observed proportions. CONCLUSIONS: It is suggested that the minimum acceptable cellularity for LBC specimens is set pragmatically by the screening programme to give a feasible percentage of repeat tests.

Carcinoma, Squamous Cell↗
PubMed2005

Can we influence medical students' approaches to learning?

Students use three approaches to learning and studying: deep, surface and strategic. These are influenced by the learning environment. In response to the General Medical Council's report 'Tomorrow's Doctors', the second year of the medical course at the University of Edinburgh was changed to promote deep learning, with learning objectives constructed according to the SOLO taxonomy, learning methods such as problem-based learning and constructively aligned written assignments and examinations. The Approaches to Study Skills Inventory for Students (ASSIST) was used to evaluate the effect of these changes. Scores were highest for deep approaches and lowest for surface approaches and showed almost no change during the course. There are various possible explanations. The students already scored highly on deep approaches at the beginning of Year 2 and it may be difficult to increase the deep scores further, particularly over the relatively short period of the study. Alternatively, the effect of the changes in learning environment may not be strong enough to change entrenched approaches which have hitherto been successful.

Cohort Studies↗
PubMed2002

Efficacy and pattern of use of sputum cytology as a diagnostic test.

Sputum cytology is regarded by many clinicians as a noninvasive, cheap and simple test for the diagnosis of bronchogenic carcinoma. Since the introduction of fibre-optic bronchoscopy and more easily obtained bronchial biopsies reliance on sputum cytology has diminished. However, in Edinburgh it was perceived that sputum samples were still being sent as well as, rather than instead of, bronchoscopic specimens. This retrospective study was undertaken to determine whether or not cytological examination of sputum is an efficient and sensitive test in the investigation of patients with suspected bronchogenic carcinoma. It demonstrated that the Lothian University Hospitals NHS Trust Pathology Directorate receives many sputa from departments not specializing in respiratory disease when there is no indication for the test. In addition, we have shown that the absolute sensitivity of the test is only 5% and that when there is a strong clinical suspicion of bronchogenic carcinoma the results of sputum cytology do not play a significant role in the management of the patient. We recommend that sputum cytology is restricted to those patients under the care of Respiratory Units in whom bronchoscopy is inappropriate or unsuccessful.

Biopsy↗
PubMed1998

Pathologists dislike sound? Evaluation of a computerised training microscope.

AIM: To evaluate the use of multimedia enhancements, using a computerised microscope, in the training of microscope skills. METHODS: The HOME microscope provides facilities to highlight features of interest in conjunction with either text display or aural presentation. A pilot study was carried out with 10 individuals, eight of whom were at different stages of pathology training. A tutorial was implemented employing sound or text, and each individual tested each version. Both the subjective impressions of users and objective measurement of their patterns of use were recorded. RESULTS: Although both versions improved learning, users took longer to work through the aural than the text version; 90% of users preferred the text only version, including all eight individuals involved in pathology training. CONCLUSIONS: Pathologists appear to prefer visual rather than aural input when using teaching systems such as the HOME microscope and sound does not give added value to the training experience.

Attitude of Health Personnel↗
PubMed1997

Should the laboratory assess the sampling adequacy of cervical smears?

The results of a questionnaire answered by 14 out of the 18 NHS laboratories in Scotland reporting cervical smears showed that, since the publication of Guidelines for Judging the Adequacy of a Cervical Smear, by the British Society for Clinical Cytology (BSCC), rates of unsatisfactory smears had risen from a mean of 3.3% to 6.5%, with some laboratories reporting rates of over 10%. Four laboratories followed the guidelines closely in requiring the presence of two indicators of sampling of the transformation zone, i.e. endocervical cells, metaplastic cells or endocervical mucus. Seven laboratories required one indicator either in all smears or in a subset, whilst three did not require any indicator at all. The laboratories observing the guidelines closely had a higher mean unsatisfactory rate than those partially observing them. The main impediment to the full implementation of the BSCC guidelines appeared to be fear of an unmanageably high unsatisfactory smear rate. The accuracy of the assessment of adequacy is questioned, as is the cost effectiveness of doing so.

Clinical Laboratory Techniques↗
PubMed1995

Interobserver variation in cell selection for DNA image cytometry.

AIMS: To describe a systematic investigation of interobserver differences in interpretation of nuclear morphology in preparations of small cell lung cancer (SCLC). METHODS: The screening/reviewing facility on the highly optimised microscope environment was used to individually tag 127 nuclei, chosen to reflect the spectrum of morphological appearances in nuclear preparations from three biopsy specimens of SCLC. Each nucleus was reviewed and labelled as control (lymphocyte), malignant or unsatisfactory by each of four observers. DNA histograms were plotted for each specimen using the nuclei identified as malignant by each participant. The histograms were compared in terms of identification of DNA stemlines and by calculation of a 5c exceeding rate (5cER). RESULTS: Interobserver variation in assessment of morphology was seen in 55.1% of nuclei. Disagreement occurred most frequently in the malignant/unsatisfactory category. Differences in morphological classification had little influence on histogram assessment by means of visual inspection but did show an effect on 5cER. CONCLUSIONS: There are significant interobserver differences in subjective assessment of nuclear morphology in cytometric preparations. This effect may seriously influence cytometric measurements.

Carcinoma, Small Cell↗
PubMed1993

A PCR approach to discriminate between integrated and episomal HPV DNA in small clinical specimens.

HPV infection has long been implicated in the development of cervical carcinoma. There is strong evidence for association of high-risk HPV types 16 and 18 with cervical intraepithelial neoplasia (CIN) grades 2 and 3, and integration of viral DNA of these types into the host genome has been suggested to play an important role in progression to invasive cervical carcinoma. However, the existing techniques for detection of integrated DNA in clinical specimens are time-consuming and require large amounts of template DNA, often unavailable for small premalignant CIN lesions. In this study, a novel, two stage PCR assay was designed to discriminate between integrated and episomal HPV 16 DNA. The first stage was designed to determine whether intact HPV genomes were present. This initial PCR analysis of the entire viral genome in eight segments was successfully applied to authentic human cervical cancers. The second stage consisted of an ANCHOR-PCR-based analysis, developed specifically to discriminate between integrated and episomal HPV DNA, that was successfully tested with cloned HPV containing plasmids used to mimic both episomal and integrated viral DNA. Further optimization and validation will be required for application of the second stage to clinical specimens. The entire assay was developed to be applicable to small colposcopic biopsies or cervical scrape samples, representative of those acquired in routine clinical investigation of CIN 2 or CIN 3, in which determination of the physical state of HPV DNA may provide prognostically valuable information.

Base Sequence↗
PubMed1993

Human papillomavirus type 18 associates with more advanced cervical neoplasia than human papillomavirus type 16.

A type-specific, sensitive, polymerase chain reaction-based assay for human papillomavirus (HPV) types 6b, 11, 16, 18, and 33 was applied to 47 cervical carcinomas, 60 cases of cervical intraepithelial neoplasia (CIN), and 24 samples of histologically normal cervix. As expected, the combined incidence of the common high-risk genital HPVs (types 16 and 18) was high in carcinomas (79%) and CIN 2/3 (60%), low in CIN 1 (25%), and nonexistent in the normal controls. Analysis of the data by viral type and pathology revealed statistically significant differences that consistently pointed to an association of HPV 18 with more advanced disease than HPV 16. This was exemplified by calculation of the relative HPV frequency in squamous cancers and CIN 2/3 lesions, which gave cancer to CIN prevalence ratios of 1.2 for HPV 16 and 2.3 for HPV 18, a twofold difference suggesting the possibility that there is a greater risk of progression or a more rapid transition to malignancy associated with HPV 18. Furthermore, HPV 16 was associated with 2.5-fold more cancers showing squamous differentiation (58%) than HPV 18 (23%), but both types showed an identical prevalence of 41% in the clinically more sinister adenocarcinomas, indicating that there may be an association between HPV type and cancer cell differentiation.

Adenocarcinoma↗
PubMed1993

PCR analysis of the upstream regulatory region of human papillomavirus genomes in cervical intraepithelial neoplasia and cervical carcinoma.

AIMS: To test whether human papillomavirus (HPV) variants with large scale sequence alterations to the upstream regulatory region are present in cervical intraepithelial neoplasias (CIN) and cervical carcinomas. METHODS: New PCR based assays were designed specifically to detect large scale insertion/deletion alterations in the upstream regulatory region of HPV 16 and 18. The assays were applied to 24 cases of CIN and 34 cases of cervical carcinoma previously shown to contain these two high risk HPV types. RESULTS: No large scale sequence alterations were found in any of the HPV containing CIN or carcinomas. CONCLUSIONS: These negative findings suggest that major upstream regulatory region variants of HPV 16 and 18 do not contribute to most cervical neoplasms.

Base Sequence↗
PubMed1991

The relationship of high-intensity signals on magnetic resonance images to cognitive and psychiatric state in Alzheimer's disease.

In Alzheimer's disease (AD), the relationship between white-matter changes on magnetic resonance images and behavior are unclear. Therefore, magnetic resonance images, cognition, and psychiatric state were assessed in patients with AD with depression (AD/DEP; n = 18) and without depression (AD; n = 45), older depressed patients (n = 12) and older normal individuals (n = 25). High-intensity signals in the cortex and subcortical regions were similar in number and proportions among all groups, even when hypertensive patients were excluded. No correlations to cognitive or psychiatric state were found. Periventricular signals were categorized using a 1- (absent) to 6- (thick, irregular caps and stripes) point scale. The categories were similar among groups except that patients with AD exhibited more category 5 changes than did normal subjects, neuropsychological performance was significantly worse in patients with AD who had category 5 and 6 changes when compared to those in category 1. These results suggest that periventricular changes may predict poor neuropsychological performance in patients with AD. However, neither deep white-matter lesions nor periventricular changes are useful for diagnostic purposes.

Aged↗
PubMed1991

HPV in full thickness cervical biopsies: high prevalence in CIN 2 and CIN 3 detected by a sensitive PCR method.

A new type-specific, sensitive, non-radioactive assay is described for the detection of human papillomavirus (HPV) DNA in tissues. Sequences within the E6 gene were amplified by the polymerase chain reaction (PCR), using primer pairs which clearly distinguish HPV types, including those with close sequence homology such as 6b and 11. The amplified DNA products were identified by non-radioactive oligonucleotide hybridization and restriction endonuclease mapping, and the method was sufficiently sensitive to detect between 3 and 5 SiHa cells (each containing 1-2 copies of HPV 16 DNA) amongst 10,000 non-HPV-containing cells. Frozen and archival paraffin sections were equally acceptable substrates for the reaction. The assay was applied to frozen sections of full thickness cervical epithelium from 60 cases of cervical intraepithelial neoplasia (CIN) and 24 normal cervical controls. HPV DNA was detected in 60 per cent of cases of CIN 3 and CIN 2, in 25 per cent of cases of CIN 1, and in none of the normal controls. Prevalence of HPV 16 was similar (approximately 50 per cent) in both CIN 2 and CIN 3, and in the whole series HPV 16 was almost five-fold more common than HPV 18. Low-risk HPV types were present in 5 per cent of CIN 1, but 0 per cent of CIN 2 and CIN 3 biopsies. The data emphasize the biological similarity of CIN 2 and CIN 3 lesions, and their divergence from CIN 1.

Adolescent↗
PubMed1991

Analysis of rare high-DNA cell populations in serous effusions using continuous-motion imaging.

The rare high-DNA cell sub-populations in a series of serous effusion specimens were analysed to determine whether such measurements could provide a basis for the improved diagnosis of malignancy. Monolayer specimens stained with gallocyanin chrome-alum were scanned with the CERVIFIP continuous-motion image analyser to locate and measure the highest-DNA cells in the sample. Two types of features were obtained for the detected sub-populations; firstly, 'percentile ploidy' values which characterise the ploidy levels above which specified proportions of the total cells are found; and secondly 'percentage abnormal' values which characterise the proportion of the cells diagnosed as malignant during examination by a cytopathologist. The classification accuracy for one or both of these features was then obtained by comparison with the clinical outcome of each patient. The results gave a classification error of 9/44 (20%) using the 0.01% percentile ploidy alone, 6/44 (14%) using the 75% percentage abnormal feature alone, but only 2/44 (5%) from a box discriminant using both features. It was therefore concluded that the analysis of the high-DNA cell population could be of value in the diagnosis of malignancy in serous effusion specimens.

Adenocarcinoma↗
PubMed1990

Sensitivity of digoxigenin and biotin labelled probes for detection of human papillomavirus by in situ hybridisation.

The sensitivity of digoxigenin and biotin labelled DNA probes for the detection of human papillomavirus (HPV) by dot blotting and in situ hybridisation was compared in tissues from cervical, laryngeal, and anogenital neoplasia. Probes were either labelled with digoxigenin by the random primer technique and detected with anti-digoxigenin antibody, or labelled with biotin by nick translation and detected with streptavidin, both methods having a common final visualisation procedure using alkaline phosphatase. Digoxigenin labelled probes proved two to 10-fold more sensitive by quantitative dot blotting and four-fold more sensitive in detecting HPV 16 DNA in a series of 31 anal carcinomas, compared with biotinylated probes. The digoxigenin method also produced less non-specific background staining of tissue sections than biotin labelled probes. It is concluded that digoxigenin DNA labelling and detection provides a simple, reliable, and efficient alternative to the use of biotin or radioactive isotopes for the detection of HPV DNA by in situ hybridisation. Digoxigenin labelled probes also offer the possibility of double labelling in situ hybridisation procedures when used with biotin labelled probes to provide simultaneous identification of different DNA sequences.

Anus Neoplasms↗
PubMed1987

Cholesteatoma following stapedectomy.

Among the possible complications of stapedectomy for otosclerosis, cholesteatoma is extremely rare. We report a case which was secondary to implantation of keratinising squamous epithelium inadvertantly included in the fat graft taken from the ear lobe to seal the footplate.

Adult↗
PubMed1985

Macrophage recognition of cells undergoing programmed cell death (apoptosis).

As a model for the recognition of effete cells by their viable neighbours. BALB/c mouse thymocytes were coincubated with isologous peritoneal macrophages. The macrophages bound preferentially to thymocytes undergoing apoptosis, a mode of death induced in these cells by treatment with the glucocorticoid hormone methyl-prednisolone. Binding occurred in the absence of serum and was inhibited by N,N'-diacetyl chitobiose, N-acetyl glucosamine and, to a lesser extent, by N-acetyl galactosamine and D-galactose. L-fucose, D-mannose and N-acetyl neuraminic acid had no effect. The results suggest the presence of lectin-like molecules on the surface of the macrophage that recognize changes in the cell-surface carbohydrate of the apoptotic cell. The pattern of inhibition of binding by monosaccharides differs from that of previously described endogenous mammalian lectins.

Animals↗