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Biomedical subjects

K Evans

Publications and source records attributed to K Evans.

At least 55 records · Page 3Linked to original sources

Randomised controlled trial of two models of care for discharged psychiatric patients.

OBJECTIVE: To compare the clinical outcome and costs of care of psychiatric patients allocated to community multidisciplinary teams or to hospital based care programmes after discharge from inpatient care. DESIGN: Randomised controlled trial. SETTING: Inner London (Paddington and North Kensington) and outer London (Brent) psychiatric services. SUBJECTS: 155 patients with severe mental illness with a previous admission within the past 2 years. MAIN OUTCOME MEASURES: Ratings of clinical psychopathology, depression, anxiety, and social functioning; comprehensive costs of health care. RESULTS: Clinical outcomes were available for 133 patients and cost data for 144 patients after 1 year. The clinical outcomes of the two models of care were essentially similar, but admission to hospital was more likely in the hospital based care group and the costs of health care were 14% greater per patient than in the community group. This difference, however, was dwarfed by a twofold difference in the costs of care in the outer London services compared with those in inner London. This was explained largely by greater inpatient care for outer London patients (58 median bed days v 18 for inner London patients), more of which was provided by extracontractual referrals to other psychiatric hospitals as Brent had only 0.28/1000 beds available for acute adult patients compared with 0.82/1000 in Paddington and North Kensington over the period of the study. CONCLUSION: Aftercare by community teams for psychiatric patients with severe mental illness has a similar outcome to hospital based aftercare but with fewer admissions to hospital. When psychiatric bed requirements are insufficient for a population, however, neither form of aftercare is effective as greater use of hospital beds elsewhere swamps any advantage of community care programmes, with disintegration and discontinuity of psychiatric services leading to escalating costs.

Adolescent↗

Estimation and relevance of depth correction in paediatric renal studies.

Measurement of absolute renal function by gamma camera techniques requires knowledge of kidney depth to correct for soft tissue attenuation, there is debate about the need to take depth into account when only relative renal function is estimated. The aim of this study was to derive a formula for renal depth in children and to assess the importance of depth correction when relative renal function is assessed with dimercaptosuccinic acid (DMSA) on the gamma camera. In this study, kidney depths were derived from measurements on abdominal computerised tomography (CT) images in 57 children in the supine position with two normally located kidneys. Using best-subset regression analysis, one formula for both left and right kidney depth (KD, cm) was developed based on the easily measured parameters of height (H, cm) and body weight (W, kg). The inclusion of extra variables was found to significantly improve the model compared with a model using weight alone (P<0.005). A second group of 19 children who underwent technetium-99m DMSA scans, had differential function estimated from both anterior and posterior views and the geometric mean method. The mean difference in differential renal function calculated by the geometric mean method versus the posterior image was only 1.2%. In conclusion, we present a new formula for the estimation of paediatric kidney depth for the absolute quantitation of kidney uptake. Further, for normally located kidneys it appears unnecessary to use the geometric mean method or to correct for individual renal depth when calculating differential function.

Adolescent↗

Rapid chylomicron appearance following sequential meals: effects of second meal composition.

Previous studies have noted the presence of an early postprandial peak in plasma triacylglycerol concentrations following successive fat-rich meals. An earlier study has shown that the triacylglycerol in this early peak originates from a previous meal. The present study was performed to investigate the effects of different second meals on the plasma triacylglycerol response. Six healthy subjects were studied on four occasions each. At 5 h following a fat-rich breakfast they ingested one of the following in a balanced design: a fat-rich meal, a low-fat meal, water or nothing by mouth. Blood samples were taken for 2.5 h following the second meal. An early peak in chylomicron and plasma triacylglycerol concentrations was seen following both low-fat and fat-rich second meals but not following water. During studies investigating postprandial lipaemia, further meals must be avoided, even if they contain no fat, although water may be allowed.

Adult↗

Recovery of positive future thinking within a high-risk parasuicide group: results from a pilot randomized controlled trial.

OBJECTIVES: The research examined: (i) whether high risk parasuicide patients showed a deficit in positive future thinking but no increase in negative future thinking; and (ii) whether such a deficit could be remedied by a brief, manual-assisted psychological intervention (manual assisted cognitive-behaviour therapy; MACT). DESIGN: A cross-sectional, mixed model design was used to assess differences between a sample of high risk parasuicide patients and matched controls on future thinking. A longitudinal mixed model design was used to assess changes in future thinking in the different groups over time. METHODS: Parasuicide patients with a history of previous suicidal behaviour and personality disturbance were compared with a matched group of community controls on an adapted fluency measure of future thinking, which measured both quantitative and qualitative aspects of anticipated experiences. Patients were then randomly allocated to either the specific intervention (MACT) or treatment as usual (TAU) and assessed again at 6 month follow-up. RESULTS: Parasuicide patients showed reduced positive future thinking but no increased negative future thinking. Patients who received MACT showed a significant improvement in positive future thinking over the follow-up period whereas the TAU group showed no such improvement. However, interpretation of this finding was made more difficult by the control group also showing a significant improvement in positive future thinking. CONCLUSION: The results confirm that parasuicide patients exhibit a relative deficit in positive future thinking and suggest that this lack of positive future thinking may be remedied, at least partly, by a brief intervention.

Adolescent↗

Influence of the MexAB-OprM multidrug efflux system on quorum sensing in Pseudomonas aeruginosa.

Pseudomonas aeruginosa nalB mutants which hyperexpress the MexAB-OprM multidrug efflux system produce reduced levels of several extracellular virulence factors known to be regulated by quorum sensing. Such mutants also produce less acylated homoserine lactone autoinducer PAI-1, consistent with an observed reduction in lasI expression. These data suggest that PAI-1 is a substrate for MexAB-OprM, and its resulting exclusion from cells hyperexpressing MexAB-OprM limits PAI-1-dependent activation of lasI and the virulence genes.

4-Butyrolactone↗

Phenotype of a British North Carolina macular dystrophy family linked to chromosome 6q.

AIMS: To document the phenotype of an autosomal dominant macular dystrophy diagnosed as having North Carolina macular dystrophy (NCMD) in this British family, and to verify that the disease locus corresponds with that of MCDR1 on chromosome 6q. METHODS: 37 family members were examined and the phenotype characterised. DNA samples from the affected members, 19 unaffected and five spouses, were used to perform linkage analysis with six microsatellite marker loci situated within the MCDR1 region of chromosome 6q. RESULTS: Every affected family member had lesions characteristic of NCMD, which developed early in life and usually remain stable thereafter. Although fundus changes are evident in the periphery, all tests revealed that functional loss is restricted to the macula. Some patients with large macular lesions had good visual acuity with fixation at the edge of the lesion at 5 degrees eccentricity. Significant linkage to the MCDR1 locus on chromosome 6q was obtained with three marker loci, with a maximum lod score of 5.9 (q = 0.00) obtained with D6S249. CONCLUSION: This family has the typical phenotype NCMD, and the causative gene was linked to the disease locus (MCDR1) on chromosome 6q. Early onset and localisation of the disease to the central macula allow specialisation of eccentric retina in some eyes with resultant good visual acuity.

Adolescent↗

Effect of storage at -70 degrees C on lipid, lipoprotein and apolipoprotein concentrations.

We have investigated the effects on lipid, apolipoprotein and lipoprotein measurements of storing unfractionated serum from normolipidaemic and hyperlipidaemic subjects at -70 degrees C for 10 days, 3 months and 6 months. Total serum concentrations of lipids and apolipoproteins were stable except for triglyceride concentrations. These increased on storage although the change was < 2.0% after 6 months. Storage of serum before sequential flotation ultracentrifugation resulted in decreased free cholesterol and phospholipid concentrations in very low density lipoproteins. In low density lipoproteins, free cholesterol concentrations increased and protein concentrations decreased on storage, while esterified cholesterol and phospholipid concentrations fell after 10 days but did not differ from baseline concentrations after storage for 6 months. Within high density lipoproteins, there were decreases in triglyceride and protein concentrations. Although storage of serum at -70 degrees C for up to 6 months did not result in extensive changes in most lipoprotein fractions, separation of lipoprotein fractions from serum should, ideally, be performed as soon as possible after collection.

Apolipoproteins↗

Assessment of the phenotypic range seen in Doyne honeycomb retinal dystrophy.

OBJECTIVE: Using molecular genetics as the basis for diagnosis, to assess the phenotype in the family originally described as having dominantly inherited Doyne honeycomb retinal dystrophy (DHRD) linked to chromosome 2p16. DESIGN: Clinical examination including fluorescein angiography was undertaken in 107 family members. Nine affected patients underwent electroretinography, perimetry, dark adaptometry, color-contrast sensitivity measurement, and autofluorescent fundus imaging. PATIENTS: The disease-associated haplotype used to allocate disease status was based on our further refinement of the DHRD locus to between loci D2S2739 and D2S378. The study identified 50 affected patients. In addition, previously published information on a further 8 individuals was used. The study population represented 6 generations of a 9-generation pedigree. RESULTS: Three types of deposits were seen: large, soft drusen at the macula and abutting the optic nerve head; small, hard deposits that in some patients radiated from the macula; and autofluorescent deposits. Most younger affected individuals exhibited small hard drusen only at the macula and had normal visual function. Information on 2 patients suggested that DHRD can be a cause of childhood-onset blindness. Advanced disease was associated with severe visual loss and posterior pole atrophy without signs of drusen. Advanced age was not invariably associated with severe visual loss. CONCLUSIONS: Previously identified characteristics of DHRD were confirmed and new features identified. Contrary to previous reports, the constancy and severity of radial (basal laminar) drusen seen clinically are the only features that can be used to differentiate between DHRD and malattia leventinese. The highly variable phenotype suggests that the influence of the DHRD-mutant gene may be modulated by other genetic and/or environmental factors.

Adult↗

Development of a radiopharmaceutical activity schedule for technetium-99m dimercaptosuccinic acid in children based on image quality criteria.

The aim of this study was to determine an activity schedule (amount of administered activity in relation to body weight) for technetium-99m dimercaptosuccinic acid examinations in children, from information present in renal scintigraphic images. Scans from 48 children (5 weeks to 14.8 years old) were graded for image quality according to the clarity of both kidney outline and internal structure. Numerical image data (kidney and background counts, signal-to-noise ratio) were associated with these subjective gradings to formulate three criteria, specifying the required values of the above-measured parameters to yield optimum grades of image quality. When applied to derived functions, a kidney uptake of 20% was required to satisfy the criterion based on the signal-to-noise ratio. Using this value with the other two criteria predicts the form of the weight-dependent activity schedule as a function of imaging time. Examples of schedules for imaging times of 300 and 600 s are compared with a schedule based on surface area.

Adolescent↗

Otomycosis: the detection of fungi in ears by immunofluorescence microscopy.

The procedure currently used to diagnose infection in otitis externa has several limitations: it is slow to culture organisms on growth media, fungal infections are often missed, and extensive laboratory facilities and mycological expertise are required. A rapid, accurate and sensitive assay would greatly improve patient care by initiating appropriate antifungal treatment at the onset of disease. We report the development of a rapid detection assay for otomycosis using fungal-specific monoclonal antibodies to detect fungi in ear swabs by immunofluorescence microscopy. This assay could form the basis of a detection assay for fungal infections of the head and neck.

Adult↗

Randomized placebo-controlled trial of brisk walking in the prevention of postmenopausal osteoporosis.

OBJECTIVE: to evaluate the effects of brisk walking on bone mineral density in women who had suffered an upper limb fracture. DESIGN: randomized placebo-controlled trial. Assessments of bone mineral density were made before and at 1 and 2 years after intervention. Standardized and validated measures of physical capacity, self-rated health status and falls were used. SETTING: district general hospital outpatient department. SUBJECTS: 165 women drawn from local accident and emergency departments with a history of fracture of an upper limb in the previous 2 years. Women were randomly allocated to intervention (self-paced brisk walking) or placebo (upper limb exercises) groups. INTERVENTION: both groups were seen at 3-monthly intervals to assess progress, measure physical capacity and maintain enthusiasm. The brisk-walking group were instructed to progressively increase the amount and speed of walking in a manner that suited them. The upper limb exercise placebo group were asked to carry out a series of exercises designed to improve flexibility and fine hand movements, appropriate for a past history of upper limb fracture. RESULTS: drop-outs from both intervention and placebo groups were substantial (41%), although there were no significant differences in bone mineral density, physical capacity or health status between drop-outs and participants. At 2 years, among those completing the trial, bone mineral density at the femoral neck had fallen in the placebo group to a greater extent than in the brisk-walking group [mean net difference between intervention and placebo groups 0.019 g/cm2, 95% confidence interval (CI) -0.0026 to +0.041 g/cm2, P = 0.056]. Lumbar spine bone mineral density had increased to a similar extent (+0.017 g/cm2) in both groups. The cumulative risk of falls was higher in the brisk-walking group (excess risk of 15 per 100 person-years, 95% CI 1.4-29 per 100 person-years, P < 0.05). There were no significant differences in clinical or spinal x-ray fracture risk or self-rated health status between intervention and placebo groups. CONCLUSION: the promotion of exercise through brisk-walking advice given by nursing staff may have a small, but clinically important, impact on bone mineral density but is associated with an increased risk of falls. Self-paced brisk walking is difficult to evaluate in randomized controlled trials because of drop-outs, placebo group exercise, limited compliance and lack of standardization of the duration and intensity of walking. Further work is needed to evaluate the best means of safely achieving increased activity levels in different groups, such as older women and those at high risk of fractures.

Accidental Falls↗

Localisation of a gene for dominant cone-rod dystrophy (CORD6) to chromosome 17p.

We have performed genetic linkage analysis on a four generation British family with cone-rod dystrophy. Significant linkage to the disease gene was obtained with eight marker loci situated on chromosome 17p12-p13. A maximum two-point lod score of 5.93 with no recombination was obtained with marker locus D17S1844. Critical recombinants identified with flanking marker loci placed the disease gene between D17S796/D17S938 and D17S954, an interval estimated to be 8 cM in size. This new localisation for autosomal dominant cone-rod dystrophy (CORD6) overlaps with regions attributed previously to Leber's congenital amaurosis, central areolar choroidal dystrophy and dominant cone dystrophy. Given their differences in phenotype, the most plausible explanation would be that these different retinal disorders are caused by mutations in different genes mapping close together within the genome.

Chromosome Mapping↗

Lipid and protein deposition of N-vinyl pyrrolidone-containing group II and group IV frequent replacement contact lenses.

PURPOSE: The purpose of this study was to investigate the degree of protein and lipid deposition that occurs on N-vinyl-2-pyrrolidone (NVP) containing group II (non-ionic, high water content) and NVP containing group IV (ionic, high water content) frequent replacement hydrogel contact lens materials. METHODS: Twenty subjects were fitted with Group II (Vasurfilcon A) and Group IV (Vifilcon A) contact lenses, which were replaced monthly. The lenses were worn as a contralateral pair for 3 consecutive monthly periods. At the end of each monthly period, the lenses were collected for analysis of protein and lipid deposits. Protein deposition (following extraction) was examined by transmission UV and lipoidal deposition was examined using fluorescence spectrophotofluorimetry. RESULTS: There was a significant difference in the lipid and protein deposition profiles between the two materials. The Group II lens deposited approximately 2x more lipid (38 versus 73 fluorescence units; P < 0.0001) and the Group IV lens deposited approximately 17x more protein (488 micrograms versus 28 micrograms; P < 0.0001). Whilst the mean results across months were not significantly different for either protein or lipid (P = NS), the results revealed significant inter- and intra-subject variation. CONCLUSIONS: Protein deposition was predominantly controlled by the ionic charge of the lens materials, whereas the lipid deposition was predominantly determined by the NVP content. This study demonstrates that inter-subject variation and material characteristics significantly influence the deposition profile of hydrogel contact lens materials.

Adolescent↗

Dosimetry of pediatric radiopharmaceuticals: uniformity of effective dose and a simple aid for its estimation.

UNLABELLED: Formulae were investigated for predicting the effective dose to children, per unit administered activity of various pediatric radiopharmaceuticals, based only on the weight of the patient. Their influence on the uniformity of effective dose from total administered activity was also examined. METHODS: The formulae were obtained from calculations of effective dose per unit administered activity (mSv x MBq[-1]) for five anthropomorphic mathematical phantoms applicable for newborn, 1-yr-, 5-yr-, 10-yr- and 15-yr-old children, having body weights of 3.4, 9.8, 19, 32 and 57 kg, respectively, using published biokinetic models. RESULTS: In general, there was good linear correlation between effective dose per unit administered activity and inverse weight but, for some radiopharmaceuticals, logarithmic regression on weight provided a better fit to the data. An administered activity schedule based on body surface area, used with these formulae, resulted in reasonable uniformity of effective dose for children of all ages, with varying degrees of uniformity for different radiopharmaceuticals (coefficient of variation (COV) up to 20%). Individual activity schedules for separate radiopharmaceuticals gave best uniformity (COV < 7%) while a single general schedule, based on the mean results of the present study, yielded acceptable uniformity (COV < or = 10%) over the pediatric range. CONCLUSION: Effective dose per unit administered activity (mSv x MBq[-1]) of pediatric radiopharmaceuticals can be predicted from body weight alone by using simple formulae, and appropriately choosing the administered activity schedule leads to similar values of effective dose for children of all ages from a given radiopharmaceutical procedure.

Adolescent↗

Surgical clips in planning the electron boost in breast cancer: a qualitative and quantitative evaluation.

PURPOSE: To evaluate, qualitatively and quantitatively, the role of surgical clips in planning the tumor bed electron boost in patients undergoing breast conserving surgery and radiotherapy. METHODS AND MATERIALS: In 50 patients, the excision cavity boundaries were marked by clips at surgery. The electron boost field was first planned using clinical information, aiming to achieve a margin of 2 cm, and its accuracy evaluated by screening the surgical clips and, if necessary, adjusting the field to encompass all clips with 2 cm margins. Orthogonal radiographs were take with solder wire delineating the clinical and screened fields and the scar. Hypothetical clinical and radiological fields, with 1 and 3 cm margins, were reconstructed on the radiographs. RESULTS: The clinical field was inadequate in 34 patients (68%). The precision of each clinical setup was quantified by two indices. The Normal Tissue Index defined the percentage of the clinical field comprised of tissue, beyond the tumor bed, not at high risk of local recurrence, and gave an estimate of potential spring of normal tissue: median 14.6% (range 0-83.0), 17 out of 50 > 25%; median 13% (range 0-70.7), 12 out of 50 > 25%; median 9.7% (range 0-59.8), 10 out of 50 > 25%, for 1, 2, and 3 cm margins, respectively. The Geographical Miss Index defined the percentage of the radiologically defined field, at high risk of local recurrence, not predicted by the clinical field, and gave an estimate of the extent of geographical miss: median 32.9% (range 0-83.5), 28 out of 50 > 25%; median 26.1% (range 0-69.8%), 26 out of 50 > 25%; median 18.6% (range 0-60.3), 20 out of 50 > 25%, for 1, 2, and 3 cm margins, respectively. The median distance from the scar midpoint to the furthest clip was 3.8 (range 1.2-8.1) cm. The median maximal clip depth was 3.1 (range 1.4-5.2) cm. CONCLUSION: (a) Electron boost field planning by clinical landmarks alone was inaccurate in 68% of cases. (b) Quantitative measures, based on margins of 1, 2, and 3 cm, revealed that in 20-34% of patients more than one-quarter of the clinical field covered tissue at low risk of local recurrence, and in 40-56% of patients less than three-quarters of the final radiological field was predicted clinically. (c) The relative positions of the scar and clips may be widely disparate. (d) Clip depth measurements reveal a significant risk of underdosing at depth.

Breast Neoplasms↗

Clinical features of progressive bifocal chorioretinal atrophy: a retinal dystrophy linked to chromosome 6q.

PURPOSE: The gene for progressive bifocal chorioretinal atrophy (PBCRA) has been linked to chromosome 6q, near the genomic assignment for North Carolina macular dystrophy. A study was undertaken to define the clinical features of a large PBCRA pedigree and to determine whether PBCRA and North Carolina macular dystrophy are phenotypically distinct entities. METHODS: Fifteen affected individuals from 1 large family were examined clinically, which included angiography and electrophysiologic studies. RESULTS: The PBCRA is an autosomal dominant chorioretinal dystrophy of early onset characterized by large atrophic macular and nasal retinal lesions, nystagmus, myopia, poor vision, and slow progression. A large atrophic macular lesion and nasal subretinal deposits are evident soon after birth. An atrophic area nasal to the optic nerve head appears in the second decade, which enlarges progressively. Electro-oculographic and electroretinographic studies indicated marked, diffuse abnormalities of rod and cone function. Fluorescein and indocyanine green angiography showed a large circumscribed area of macular choroidal atrophy with staining of deposits in the peripheral retina. In addition to previously documented features, nasal retinal abnormalities from a few weeks of age, marked photopsia in a number of patients, and retinal detachments in three eyes are reported as new features of the disease. CONCLUSIONS: An extended description of PBCRA is presented highlighting that the phenotype is distinct from North Carolina macular dystrophy, although some phenotypic similarities exist between the two conditions. These disorders may be the result of different mutations on the same gene or nearby genes.

Adolescent↗