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Biomedical subjects

A L Evans

Publications and source records attributed to A L Evans.

At least 19 recordsLinked to original sources
PubMed2006

Diagnosis of suspected venous thromboembolic disease in pregnancy.

Venous thromboembolic disease is a leading cause of maternal mortality during pregnancy. Early and accurate radiological diagnosis is essential as anticoagulation is not without risk and clinical diagnosis is unreliable. Although the disorder is potentially treatable, unnecessary treatment should be avoided. Most of the diagnostic imaging techniques involve ionizing radiation which exposes both the mother and fetus to finite radiation risks. There is a relative lack of evidence in the literature to guide clinicians and radiologists on the most appropriate method of assessing this group of patients. This article will review the role of imaging of suspected venous thromboembolic disease in pregnant patients, highlight contentious issues such as radiation risk, intravenous contrast use in pregnancy and discuss the published guidelines, as well as suggesting an appropriate imaging algorithm based on the available evidence.

Algorithms↗
PubMed2005

First-line investigation of acute intracerebral hemorrhage using dynamic magnetic resonance angiography.

PURPOSE: To report the initial experience of magnetic resonance (MR) digital subtraction angiography (MR-DSA) in the dynamic assessment of the cerebral circulation in acute non-traumatic intracerebral hemorrhage (ICH). MATERIAL AND METHODS: Twelve patients with acute ICH were investigated within 6 days of the ictus using a dynamic contrast-enhanced 2-D MR angiogram that produces subtracted images with a temporal resolution of 1-2 frame/s. The MR-DSA examinations were assessed for evidence of an intracranial vascular abnormality and were compared with (i) the routine MR sequences, (ii) non-dynamic time-of-flight MR angiography, and (iii) catheter angiogram performed during the same admission. RESULTS: All 12 MR-DSA examinations were considered to be technically satisfactory. MR-DSA detected an intracranial vascular abnormality in 7 patients (3 arteriovenous malformations, 2 aneurysms, 1 dural arteriovenous fistula, and 1 venous thrombosis). All abnormalities were confirmed by catheter angiography with the exception of one patient with venous sinus thrombosis found on MR imaging that did not undergo catheter angiography. All four arteriovenous shunts were detected by MR-DSA by virtue of early venous filling. CONCLUSION: MR-DSA can be performed satisfactorily in the setting of acute ICH and provides an alternative method to catheter angiography for identifying shunting vascular abnormalities such as arteriovenous malformations and fistulae, as well as large aneurysms and venous occlusions. MR-DSA is a contrast-medium-based technique that does not suffer from the T1 shortening effects of acute hemorrhage that can obscure abnormalities on conventional flow-based non-dynamic techniques.

Adult↗
PubMed2005

Recurrent bacterial vaginosis: the use of maintenance acidic vaginal gel following treatment.

Bacterial vaginosis (BV) frequently recurs after treatment. One option in the management of recurrences is to keep the vaginal pH at 4.5 or less, in order to prevent overgrowth of bacteria, until the normal lactobacilli are re-established. We report the outcome of using maintenance acetic acid vaginal gel, after treatment of BV, in a sample of 49 women with frequent recurrences. Half of the women had no further recurrences, and in those who did there was a significant increase in time to first recurrence (4.8 months) after commencing the gel compared with the previous recurrence (2.1 months). Prior to using acidic gel, the mean recurrence rate in 49 women was 4.4 per woman/year, and this was reduced to 0.6 recurrences per woman/year. As there are few effective therapies for women with recurrent BV, we feel this offers an option that can currently be used in clinical practice.

Adult↗
PubMed2004

An evaluation of the use of tooth temperature to assess human pulp vitality.

AIM: To evaluate change in tooth surface temperature following a thermal stimulus as a simple and reliable method to assess the presence and the extent of blood flow through teeth. METHODOLOGY: Miniature thermometers were used to measure the relationship between surface temperature of teeth and internal flow of 37 degrees C water (in vitro) or blood (in vivo). In addition, thermal stimuli were applied to the external surface of the teeth, and the rate of temperature recovery was related to internal flow. RESULTS: Under in vitro conditions, the surface temperature of teeth and rate of temperature recovery were related to the rate of internal water flow. However, in vivo neither standing surface temperature (P = 0.47) nor rate of temperature recovery (P = 0.19) were significantly related to evidential pulp vitality. CONCLUSION: Change in the surface temperature of teeth is not suitable as a simple clinical means to assess pulp vitality.

Adult↗
PubMed2003

The Strengths and Difficulties Questionnaire: a pilot study of a new computer version of the self-report scale.

A computer-based version of the self-report Strengths and Difficulties Questionnaire (SDQ) was developed with colourful graphics illustrating each question. One hundred and two children referred to child and adolescent mental health services were recruited and randomly allocated to complete either the new computer-based version or the paper original. A further 112 children from local schools were recruited and completed the computer-based version of the scale. All children who took part in the study were aged between 8 and 15 years. The paper version of the SDQ is recommended for use in children aged 11 and over and, in this age group, the computer-based questionnaire was able to discriminate between the clinical and community sample (ROC = 0.761, 95 % CI 0.676-0.846). Comparison of the paper-based SDQ and computer-based SDQ within the clinic sample found trends towards better test-retest reliability, inter-rater reliability and significantly better user satisfaction in the computer version compared to the paper-based version. The computer-based SDQ has the added advantage of results being automatically added to a spreadsheet out of view from the user reducing the chance of operator error in coding and entering the data. These preliminary results suggest that the computer-based version of the SDQ may represent a further improvement on the paper SDQ. All versions of the SDQ, including the computer-based version, can be downloaded from the Strengths and Difficulties website address www.sdqinfo.com.

Adolescent↗
PubMed2003

The effect of RU486 on the gene expression profile in an endometrial explant model.

Administration of RU486 in vivo during the receptive phase rapidly renders the endometrium non-receptive to the implanting embryo. In order to identify key pathways responsible for endometrial receptivity we have used cDNA arrays to monitor gene expression changes in short-term endometrial explants in response to RU486. Endometrial biopsies from five normal fertile women at mid-secretory phase were cultured in the presence of estradiol and progesterone with or without RU486 for 12 h. cDNA arrays were produced containing approximately 1000 sequence-verified clones which included genes known to be important in angiogenesis, apoptosis, cell signalling, extracellular matrix remodelling and cell cycle regulation. cDNA probes from the paired endometrial samples were hybridized to the arrays and hybridization signals were quantified. A total of 12 genes displayed significant changes in expression; six were up-regulated and six down-regulated following RU486 treatment. For five of these genes this is the first report suggesting that they are regulated by steroids in the endometrium. JAK1 and JNK1 were two of the genes shown by the arrays to be down-regulated in RU486-treated endometrial explants. This was confirmed by real time RT-PCR. JAK1 immunoreactivity was localized to both glandular epithelium and the stroma of normal endometrium and staining was much stronger in the luteal phase of the cycle. These results show that components of two important signalling pathways in endometrium-the JAK/STAT pathway, and the JNK pathway-are altered by RU486. Genes whose expression is controlled by these pathways are likely to be involved in the mechanism by which steroids render the endometrium receptive to the implanting embryo.

Adult↗
PubMed2002

Identification of FBN1 gene mutations in patients with ectopia lentis and marfanoid habitus.

BACKGROUND: Marfan syndrome (MFS), inherited as an autosomal dominant trait, typically affects the cardiovascular, skeletal, and ocular systems. Ectopia lentis (EL) is a clinical manifestation of MFS, with stretching or disruption of the lenticular zonular filaments, leading to displacement of the lenses. EL, with or without minor skeletal changes, exists as an independent autosomal dominant phenotype linked to the same FBN1 locus. METHODS: A consecutive series of 11 patients, affected predominantly by EL, was analysed for FBN1 mutations using PCR, SSCA, and sequencing. RESULTS: Six mutations were identified, of which three are novel and one is recurrent in two patients, thus establishing a mutation incidence in this group of 7/11 (63%). CONCLUSION: The FBN1 variants reported are clustered in the first 15 exons of the gene, while FBN1 mutations reported in the literature are distributed throughout the entire length of the gene. A different type of FBN1 mutation presents in this group of patients, compared with MFS, with arginine to cysteine substitutions appearing frequently.

Adult↗
PubMed2001

Detection of six novel FBN1 mutations in British patients affected by Marfan syndrome.

Marfan syndrome (MFS), an autosomal dominant disorder of the extracellular matrix, is due to mutations in fibrillin-1 (FBN1) gene. Investigations carried out in the last decade, unveiled the unpredictability of the site of the mutation, which could be anywhere in the gene. FBN1 mutations have been reported in a spectrum of diseases related to MFS, with no clear evidence for a phenotype-genotype correlation. In this paper we analysed 10 British patients affected by MFS and we were able to characterise five novel missense mutations (C474W, C1402Y, G1987R, C2153Y, G2536R), one novel frameshift mutation (7926delC), one already described mutation (P1424A) and one FBN1 variant (P1148A) classified as a polymorphism in the Asian population. Four out of the five novel missense mutations involved either cysteines or an amino acid conserved in the domain structure. The mutation yield in this study is calculated at 80.0% (8/10), thus indicating that SSCA is a reliable and cost-effective technique for the screening of such a large gene. Our results suggest that this method is reliable to search for FBN1 mutations and that FBN1 screening could be a helpful tool to confirm and possibly anticipate the clinical diagnosis in familial cases. Hum Mutat 18:251, 2001.

Adult↗
PubMed2001

Erratum: Detection of six novel FBN1 mutations in British patients affected by Marfan syndrome.

Marfan syndrome (MFS), an autosomal dominant disorder of the extracellular matrix, is due to mutations in fibrillin-1 (FBN1) gene. Investigations carried out in the last decade, unveiled the unpredictability of the site of the mutation, which could be anywhere in the gene. FBN1 mutations have been reported in a spectrum of diseases related to MFS, with no clear evidence for a phenotype-genotype correlation. In this paper we analysed 10 British patients affected by MFS and we were able to characterise five novel missense mutations (C474W, C1402Y, G1987R, C2153Y, G2536R), one novel frameshift mutation (7926delC), one already described mutation (P1424A) and one FBN1 variant (P1148A) classified as a polymorphism in the Asian population. Four out of the five novel missense mutations involved either cysteines or an amino acid conserved in the domain structure. The mutation yield in this study is calculated at 80.0% (8/10), thus indicating that SSCA is a reliable and cost-effective technique for the screening of such a large gene. Our results suggest that this method is reliable to search for FBN1 mutations and that FBN1 screening could be a helpful tool to confirm and possibly anticipate the clinical diagnosis in familial cases.

Adult↗
PubMed2001

The impact of fixation on the multifocal electroretinogram.

There are a number of variables which can influence the quality of multifocal ERG waveforms. In common with visual field measurements, fixation quality may be an important parameter on the integrity of the acquired data. A low cost, fixation-monitoring device was used to assess fixation quality on a group of normal volunteers. Data was successfully acquired while five subjects viewed a fixation target for a period of time equal to that of a single multifocal recording segment. The target was presented on a stationary grey background and as the central fixation mark on a 61-element multifocal flicker stimulus. The results show no significant difference with or without the flickering pattern. The percentage of samples falling within 1.2 degrees of the point of fixation was 51%. This suggests that fixation quality is adequate for scaled stimuli where the central element subtends 2.4 degrees. High resolution stimuli of less than 2.4 degrees may be more susceptible to fixation fluctuations during the recording process.

Adult↗
PubMed2001

An automated dosimetry system for testing whole-body ultraviolet phototherapy cabinets.

A new technique is described for automated ultraviolet dosimetry within whole-body phototherapy cabinets. A dual-head detector system has been designed, permitting simultaneous assessment of irradiance levels and radiant intensities from individual lamps. One detector is used in combination with a diffuser/filter system for the measurement of irradiance and the other is mounted at the end of a slit collimator to provide a measurement which can be related to the radiant intensities of the individual lamps. These quantities are derived from 800 separate measurements made during rotation of the detector head around a 360 degrees circle at a fixed height and position within the cabinet under remote computer software control. The device has advantages compared with standard techniques, enabling measurements to be made without the need for a person to be present in the cabinet. A full set of measurements is made with minimal switching of the power supply to the lamps. This simplifies the assessment and reduces the uncertainty from variation in output after the lamps are switched on. Variations in irradiance with orientation for the smaller phototherapy cabinets are clearly demonstrated. Plots of data from the collimated detector show peaks corresponding to the lamps and the surrounding reflectors. The plots enable failed lamps to be detected and peak values can be related to radiant intensities of individual lamps.

Biophysical Phenomena↗
PubMed2000

Non-syndromic mental retardation segregating with an apparently balanced t(1;17) reciprocal translocation through three generations.

We describe a family in which non-syndromic mental retardation (MR) and an apparently balanced reciprocal translocation, t(1;17)(p36. 3;p11.2) segregates in eight individuals over three generations. Four children showed psychomotor developmental delay, reduced muscle tone, poor coordination, and learning difficulties. The affected adults had a varying range of behavioral problems and difficulties in social adjustment but no abnormal neurological signs. Most of them were functioning at the borderline learning difficulty level in intellectual abilities with additional specific difficulties in reading in two individuals. The Smith-Magenis and 1p36.3 deletion syndromes were excluded. We propose that this reciprocal translocation has disrupted an autosomal gene with an important function in cognitive development, and this family represents a unique resource for the molecular genetic study on non-syndromic MR.

Adolescent↗
PubMed1999

Three-dimensional electromagnetic model of the human eye: advances towards the optimisation of electroretinographic signal detection.

Classical electromagnetic theory is used to examine the topographical variation in electrical potentials over the corneal surface resulting from specific retinal stimuli. Results from a three-dimensional mathematical model show that over 97% of calculated electromagnetic field potentials lie within 3% of previous analytical model data for an axially symmetric case. Maps of corneal potentials are produced that are shown to be characteristic of specific retinal stimuli and location. The maximum variation in corneal potential for a full field global stimulus is found to be approximately 1%. This is considered encouraging, as current electrophysiology techniques measure ocular potentials from a single corneal or scleral site, the position of which is often difficult to localise and reproduce. The model is used to simulate both central and peripheral stimuli and scotoma conditions. A 20 degrees central scotoma simulation shows an overall reduction in central corneal potential of only 3%, whereas peripheral stimuli are found to cause up to 10% variations in this potential. There is therefore a possibility that a single recording site for multifocal retinal stimulation is not ideal. These data may be used to suggest more appropriate electrode recording positions for maximum signal recovery, not least in optimising signal detection for multi-focal electroretinography stimulation.

Electromagnetic Fields↗
PubMed1999

Pseudoseizures as a complication of painful cervical ribs.

An 8-year-old girl is described who presented with seizures. These were subsequently found to be pseudoseizures, with no EEG changes. They were provoked by pain from cervical ribs. This cause of pain-provoked pseudoseizures has not previously been described.

Anxiety, Separation↗
PubMed1999

Mapping of primary congenital lymphedema to the 5q35.3 region.

Primary lymphedema is a chronic tissue swelling, most frequently of the lower limbs, resulting from deficient lymphatic drainage. The variability of the affected phenotype, incomplete penetrance, lack of large families, and possible genetic heterogeneity have hampered the identification of causative genes until now. We carried out a genomewide search, using a four-generation North American family with dominantly inherited primary congenital lymphedema (PCL), otherwise known as "Milroy disease," or "hereditary lymphedema type I" (MIM 153100). Linkage to markers from the 5q35.3 region in this and four additional, British families was established. A minimum of 79 directly scorable haplotypes (37 affected) in five families conspicuously segregated with the most telomeric region of 5q35.3, thus suggesting a major locus for PCL in this vicinity. No recombination was observed with D5S408 (Z = 10.03) and D5S2006 (Z = 8.46) with a combined multipoint score of 16.55. While D5S2073 and WIAF-2213 defined the upper centromeric boundary, no recombinants were obtained for the last telomeric marker of D5S2006. Four unaffected subjects were identified as gene carriers and provided an estimated penetrance ratio of.84 for this condition. A few of the positionally mapped genes in the 5q35 region that may potentially be involved in the etiology of this condition are CANX, FGFR4, HK3, and hnRPH1.

Chromosome Mapping↗