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Biomedical subjects

T Johnson

Publications and source records attributed to T Johnson.

At least 19 recordsLinked to original sources

Imaging of aortic abnormalities with contrast-enhanced ultrasound. A pictorial comparison with CT.

Aortic abnormalities are commonly encountered and may represent a diagnostic challenge in patients with acute or chronic clinical symptoms. Contrast-enhanced ultrasound (CEUS) with low mechanical index (low MI) is a new promising method in the diagnosis and follow-up of pathological aortic lesions. CEUS with SonoVue allows a more rapid and noninvasive diagnosis, especially in critical patients because of its bedside availability. This review compares CEUS findings with those documented on computed tomography angiography (CTA), allowing the reader to appreciate the usefulness of CEUS in this clinical situation.

Aortic Dissection↗

Color Doppler, power Doppler and B-flow ultrasound in the assessment of ICA stenosis: Comparison with 64-MD-CT angiography.

The purpose of this study is to investigate the diagnostic potential of color-coded Doppler sonography (CCDS), power-Doppler (PD) and B-flow ultrasound in assessing the degree of extracranial internal carotid artery (ICA) stenosis in comparison to CT-angiography (MD-CTA). Thirty-two consecutive patients referred for CTA with 41 ICA-stenoses were included in this prospective study. MD-CTA was performed using a 64 row scanner with a CTDIvol of 13.1 mGy/cm. In CTA, CCDS, PD and B-flow, the degree of stenosis was evaluated by the minimal intrastenotic diameter in comparison to the poststenotic diameter. Two radiologists performed a quantitative evaluation of the stenoses in consensus blinded to the results of ultrasound. These were correlated to CTA, CCDS, PD and B-flow, intraoperative findings and clinical follow-up. Grading of the stenoses in B-flow ultrasound outperformed the other techniques in terms of accuracy with a correlation coefficient to CTA of 0.88, while PD and CCDS measurements yield coefficients of 0.74 and 0.70. Bland-Altman analysis additionally shows a very little bias of the three US methods between 0.5 and 3.2 %. There is excellent correlation (coefficient 0.88, CI 0.77-0.93) with 64-MD-CTA and B-flow ultrasound in terms of accuracy for intrastenotic and poststenotic diameter. Duplex sonography is useful for screening purposes.

Aged↗

High-grade stenoses of the internal carotid artery: comparison of high-resolution contrast enhanced 3D MRA, duplex sonography and power Doppler imaging.

PURPOSE: The objective of this study was to determine the agreement and diagnostic accuracy of high-resolution contrast enhanced magnetic resonance angiography (MRA) with integrated parallel acquisition techniques (iPAT), color coded duplex ultrasound (CCDS) and power Doppler ultrasound (PD) in the assessment of high-grade stenoses of the internal carotid artery (ICA). METHODS: Forty-four patients with 52 known or suspected stenoses of the internal carotid artery (ICA) were included in this prospective study. High-resolution MRA scans with a spatial resolution of 0.9 mm x 0.7 mm x 0.9 mm were acquired with an iPAT acceleration factor of 2 on a 1.5T MR system (Sonata Maestro Class, Siemens Medical Solutions, Erlangen, Germany) with a head, neck and body coil. For the 3D-CE MRA a fast spoiled gradient echo sequence (FLASH) was used. To compensate for the inherent signal loss with parallel imaging, a 1M contrast agent (gadobutrol, Gadovist, Schering, Berlin, Germany) was used. Stenoses were quantified by two readers in consensus in cross-sectional area measurements and graded according to the NASCET criteria. Using color coded duplex ultrasound (CCDS) and power Doppler (PD; Logiq 9, GE), the stenoses were also graded by two readers in consensus according to the NASCET criteria from intra- and post-stenotic diameter measurements. The results of MRA, CCDS and PD were compared to intraoperative findings or to follow-up examinations. RESULTS: High-resolution MRA allowed an excellent grading of vascular stenoses. In 70-90% degrees of stenosis there was an underestimation of the degree of stenosis in MRA as well as in CCDS. However, there was an overestimation of 90% stenoses in both MRA and CCDS. Pseudoocclusions with a lumen of less than one millimeter were occasionally rated as a complete occlusion in MRA. CONCLUSION: A combination of MRA and duplex sonography seems reasonable for the accurate grading of stenoses and determination of distal stenoses downstream. However, the accuracy of duplex ultrasound depends on the examiner's experience.

Aged↗

Agouti-related protein promoter variant associated with leanness and decreased risk for diabetes in West Africans.

OBJECTIVE: The role of the central melanocortin system in the development of obesity has been extensively studied. Single-nucleotide polymorphisms (SNPs) within several candidate genes have been associated with food intake and obesity-related phenotypes; however, few of these associations have been replicated. SNPs in the agouti-related protein (AGRP) gene coding (Ala67Thr, 199G/A) and promoter (-38C/T) have been reported to be associated with body mass index (BMI), fat mass (FM) and percent body fat, in populations of European and African descent. In this study, we evaluated the association between the functional AGRP -38C/T promoter SNP and weight-related traits, namely BMI, FM and fat-free mass (FFM), as well as diabetes status. DESIGN: An association study of the AGRP -38C/T SNP and indices of obesity and diabetes status. SUBJECTS: A well-characterized population of 538 West Africans from Ghana and Nigeria recruited in the AADM (Africa America Diabetes Mellitus) study (mean age 52 years, 41.3% males, 71% diabetic). MEASUREMENTS: Genotyping of the AGRP -38C/T SNP, BMI, FM, FFM and fasting plasma glucose. RESULTS: Women carrying two copies of the variant T allele had significantly lower BMI (OR=0.47; 95% CI, 0.25-0.87). Also, men with at least one copy of the variant T allele were over two times less likely to be diabetic than other men (OR=0.44; 95% CI, 0.22-0.89). CONCLUSION: Our results replicate previous findings and implicate the AGRP -38C/T SNP in the regulation of body weight in West Africans.

Agouti Signaling Protein↗

Treatment of active Crohn's disease in children using partial enteral nutrition with liquid formula: a randomised controlled trial.

BACKGROUND AND AIMS: Total enteral nutrition (TEN) with a liquid formula can suppress gut inflammation and induce remission in active Crohn's disease. The mechanism is obscure. Studies have suggested that long term nutritional supplementation with a liquid formula (partial enteral nutrition (PEN)) may also suppress inflammation and prevent relapse. The aim of this study was to compare PEN with conventional TEN in active Crohn's disease. PATIENTS AND METHODS: Fifty children with a paediatric Crohn's disease activity index (PCDAI)>20 were randomly assigned to receive 50% (PEN) or 100% (TEN) of their energy requirement as elemental formula for six weeks. The PEN group was encouraged to eat an unrestricted diet while those receiving TEN were not allowed to eat. The primary outcome was achievement of remission (PCDAI<10). Secondary analyses of changes in erythrocyte sedimentation rate (ESR), C reactive protein, albumin, and platelets were performed to look for evidence of anti-inflammatory effects. RESULTS: Remission rate with PEN was lower than with TEN (15% v 42%; p=0.035). Although PCDAI fell in both groups (p=0.001 for both), the reduction was greater with TEN (p=0.005). Moreover, the fall in PCDAI with PEN was due to symptomatic and nutritional benefits. With both treatments there were significant improvements in relation to abdominal pain, "sense of wellbeing", and nutritional status. However, only TEN led to a reduction in diarrhoea (p=0.02), an increase in haemoglobin and albumin, and a fall in platelets and ESR. CONCLUSIONS: TEN suppresses inflammation in active Crohn's disease but PEN does not. This suggests that long term nutritional supplementation, although beneficial to some patients, is unlikely to suppress inflammation and so prevent disease relapse.

Adolescent↗

A genome-wide scan for quantitative trait loci linked to obesity phenotypes among West Africans.

OBJECTIVE: To identify quantitative trait loci (QTL) for three obesity phenotypes: body mass index (BMI), fat mass (FM) and percent body fat (PBF) in West Africans with type 2 diabetes (T2DM). DESIGN: An affected sibling pair (ASP) design, in which both siblings had T2DM. Obesity was analyzed as a quantitative trait using a variance components approach. SUBJECTS: Sib-pairs affected with T2DM from the Africa America Diabetes Mellitus (AADM) study, comprising 321 sibling pairs and 36 half-sibling pairs. MEASUREMENTS: Weight was measured on an electronic scale to the nearest 0.1 kg, and height was measured with a stadiometer to the nearest 0.1 cm. Body composition was estimated using bioelectric impedance analysis (BIA). Genotyping was carried out at the Center for Inherited Disease Research (CIDR) with a panel of 390 trinucleotide and tetranucleotide repeats. RESULTS: The obesity-related phenotype showing the strongest linkage evidence was PBF on chromosome 2 (LOD 3.30 at 72.6 cM, marker D2S739). Suggestive linkage to FM was found on chromosomes 2 (LOD 2.56 at 80.4 cM) and 5 (LOD 2.25 at 98 cM, marker D5S1725). The highest LOD score for BMI was 1.68 (chromosome 4, 113.8 cM). The areas of linkage for the three phenotypes showed some clustering as all three phenotypes were linked to the same regions of 2p13 and 5q14, and our study replicated linkage evidence for several regions previously reported in other studies. CONCLUSION: We obtained evidence for several QTLs on chromosome 2, 4 and 5 to three obesity phenotypes. This study provides data on the genetics of obesity in populations that are currently under represented in the global effort directed at understanding the pathophysiology of excess adiposity in free living individuals.

Adipose Tissue↗

Multipoint linkage disequilibrium mapping using multilocus allele frequency data.

This paper describes a likelihood based fine scale linkage disequilibrium mapping method for estimating the position of a disease predisposing gene relative to a battery of typed marker loci. The method uses multilocus allele frequency data from a sample of unrelated diseased individuals and from a sample of unrelated control individuals, that is, a case and control type design. This type of data could be obtained by typing DNA pools, which is less expensive than typing individuals separately. The method described uses a nonparametric model that makes it robust to the shape of the genealogy at the disease locus. It can be implemented efficiently, making a multipoint analysis of a data set of a thousand markers feasible. An example power analysis uses simulations to estimate the amount of information that can be extracted from fully resolved haplotype data, relative to multilocus allele frequency data. For the assumed parameter values and a battery of 10 markers, roughly three times narrower region estimates can be derived from haplotype data than from allele frequency data only. Depending on how we choose to measure information, allele frequency data at an additional approximately 18 or approximately 33 markers is needed to compensate for this loss of information.

Alleles↗

The Nottingham study of neurotic disorder: predictors of 12 year costs.

OBJECTIVE: To examine the relationship between clinical, demographic and socio-economic characteristics and the long-term costs of a cohort of neurotic patients. METHOD: Analysis of the costs of a cohort of 210 people entered in the Nottingham study of neurotic disorders, a randomized controlled evaluation of five treatments for neurotic disorders. Service use data were collected at 5 and 12 years after study entry. Multiple regression analyses were conducted. RESULTS: The total cost per patient over the 12-year follow-up period was calculated to be $11,940 (SD $15,520) ( pound7450, SD pound9690). Higher costs were significantly associated with the presence of general neurotic syndrome, an initial diagnosis of dysthymia and a recurrent episode of illness. CONCLUSION: The total costs of care for a range of neurotic disorders are broadly comparable with other estimates of costs reported in the literature for similar populations. Those responsible for higher costs in the longer-term have comorbid anxiety, depressive and personality disorders.

Adult↗

Five years of treatment with risedronate and its effects on bone safety in women with postmenopausal osteoporosis.

We have recently reported that risedronate preserves normal bone formation and decreases bone remodeling in women with postmenopausal osteoporosis after 3 years of treatment. We report now the results of a 2-year extension study. The primary objective of this study was to determine the effect of 5 years of risedronate treatment (5 mg daily) on bone quality and bone remodeling based on paired transiliac bone biopsies. There were additional measurements that included bone turnover markers and bone mineral density (BMD). Histologic evaluation of biopsy sections (placebo, n = 21; risedronate, n = 27) yielded no pathologic findings after 5 years in either treatment group. Histomorphometric assessment of paired biopsy specimens after 5 years (placebo, n =12; risedronate, n = 13) found no statistically significant differences between treatment groups in structural or resorption parameters. There was a significant reduction in osteoid (-27%) and mineralizing surfaces (-49%) from baseline values in the risedronate group that were also significantly different from placebo at 5 years. Similarly, activation frequency decreased significantly (-77%) in the risedronate group, although it was not significantly different from placebo at 5 years (0.09 vs. 0.21, respectively). Double tetracycline labels were identified in all biopsy specimens indicating continuous bone turnover. After 5 years of risedronate treatment, serum bone-specific alkaline phosphatase (bone ALP) and N-telopeptide (NTX) decreased significantly from baseline by 33.3% and 47.5%, respectively. In the placebo group, bone ALP decreased by 3.9% (P = NS), whereas NTX decreased by 27.0% (P < 0.005). Lumbar spine BMD increased significantly in the risedronate group (9.2%), whereas no significant change was seen in the placebo group (-0.26%). Risedronate was overall well tolerated; during the 2-year study extension nonvertebral fractures occurred in 7 patients in placebo and 2 patients in risedronate groups. The findings from this study are consistent with the antiremodeling effect of risedronate and support long-term bone safety and antifracture efficacy of risedronate treatment.

Aged↗

Tissue transglutaminase in normal and abnormal wound healing: review article.

A complex series of events involving inflammation, cell migration and proliferation, ECM stabilisation and remodelling, neovascularisation and apoptosis are crucial to the tissue response to injury. Wound healing involves the dynamic interactions of multiple cells types with components of the extracellular matrix (ECM) and growth factors. Impaired wound healing as a consequence of aging, injury or disease may lead to serious disabilities and poor quality of life. Abnormal wound healing may also lead to inflammatory and fibrotic conditions (such as renal and pulmonary fibrosis). Therefore identification of the molecular events underlying wound repair is essential to develop new effective treatments in support to patients and the wound care sector. Recent advances in the understating of the physiological functions of tissue transglutaminase a multi functional protein cross-linking enzyme which stabilises tissues have demonstrated that its biological activities interrelate with wound healing phases at multiple levels. This review describes our view of the function of tissue transglutaminase in wound repair under normal and pathological situations and highlights its potential as a strategic therapeutic target in the development of new treatments to improve wound healing and prevent scarring.

Animals↗

Destabilization of fast-ion-induced long sawteeth by localized current drive in the JET tokamak.

In a tokamak fusion reactor the energetic alpha particles will transiently stabilize the magnetohydrodynamic activity causing sawtooth oscillations. The crash events terminating long sawtooth free periods can provide seed islands for neoclassical tearing modes [Phys. Rev. Lett. 88, 105001 (2002)]]. To shorten the sawtooth periods localized current drive near the q=1 surface is a possibility. This Letter provides the first experimental evidence for the effectiveness of this method in the different physics regime associated with fast-ion-induced long sawteeth on the JET tokamak.

Journal Article↗

Plasma rotation induced by directed waves in the ion-cyclotron range of frequencies.

Changes of the toroidal plasma rotation induced by directed waves in the ion-cyclotron range of frequencies (ICRF) have been identified experimentally for the first time on the JET tokamak. The momentum carried by the waves is initially absorbed by fast resonating ions, which subsequently transfer it to the bulk plasma. Thus, the results provide evidence for the influence of ICRF heated fast ions on plasma rotation.

Journal Article↗

Ozone therapy for the treatment of dental caries.

BACKGROUND: Dental caries is a bacterially mediated disease characterised by demineralisation of the tooth surface, which may lead to cavitation, discomfort, pain and eventual tooth loss. Ozone is toxic to certain bacteria in vitro and it has been suggested that delivering ozone into a carious lesion might reduce the number of cariogenic bacteria. This possibly could arrest the progress of the lesion and may, in the presence of fluoride, perhaps allow remineralisation to occur. This may in turn delay or prevent the need for traditional dental conservation by 'drilling and filling'. OBJECTIVES: To assess whether ozone is effective in arresting or reversing the progression of dental caries. SEARCH STRATEGY: We searched the Cochrane Oral Health Group's Trials Register (to 7 November 2003); Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 3, 2003); MEDLINE and PREMEDLINE (OVID, 1966 to November 2003); EMBASE (OVID, 1980 to November 2003); CINAHL (OVID, 1982 to November 2003); AMED (OVID, 1985 to November 2003). Quintessence was handsearched through 2002 and KaVo were contacted as manufacturers of the HealOzone apparatus for any additional published or unpublished trials. SELECTION CRITERIA: Inclusion was assessed independently by at least two reviewers. Trials were only included if they met the following criteria: randomisation in a controlled trial; single surface in vivo carious lesion accessible to ozone application; clear allocation concealment; ozone application to the lesions in the intervention group; no such application of ozone in the control group; outcomes measured after at least 6 months. DATA COLLECTION AND ANALYSIS: Reviewers independently extracted information in duplicate. A paucity of comparable data did not allow meta-analytic pooling of the included studies. MAIN RESULTS: Three trials were included, with a combined total of 432 randomised lesions (137 participants). Forty-two conference papers, abstracts and posters were excluded (from an unknown number of studies). The risk of bias in all studies appeared high. The analyses of all three studies were conducted at the level of the lesion, which is not independent of the person, for this reason pooling of data was not appropriate or attempted. Individual studies showed inconsistent effects of ozone on caries, across different measures of caries progression or regression. Few secondary outcomes were reported, but one trial reported an absence of adverse events. REVIEWERS' CONCLUSIONS: Given the high risk of bias in the available studies and lack of consistency between different outcome measures, there is no reliable evidence that application of ozone gas to the surface of decayed teeth stops or reverses the decay process. There is a fundamental need for more evidence of appropriate rigour and quality before the use of ozone can be accepted into mainstream primary dental care or can be considered a viable alternative to current methods for the management and treatment of dental caries.

Cariostatic Agents↗

[Quantitative analysis of left ventricular wall motion with MRI tagging].

PURPOSE: The purpose of this study was to establish a quantification of different parameters of left ventricular wall motion from tagged MR images. This evaluation method was to be applied to characterize the physiological contraction cycle and to determine pathophysiological changes. MATERIALS AND METHODS: Myocardial tagging was performed at a basal, a mid-ventricular and an apical level of the left ventricle. A suitable software was programmed for the automatic quantification of rotation, contraction and circumferential shortening. The evaluation method was used in 8 healthy volunteers, 13 patients suffering from aortic stenosis before and one year after surgery and in 10 patients with myocardial infarction before and after revascularization. RESULTS: The software allows the quantification of left ventricular wall motion by assessment of rotation, contraction and circumferential shortening. In the healthy volunteers, there was a wringing motion with opposite rotation of base and apex of the heart. Before valve replacement, patients with aortic stenosis showed significantly increased apical rotation and torsion. One year after surgery, left-ventricular torsion had normalized. In patients with myocardial infarction, circumferential shortening increased after revascularization. CONCLUSION: The quantification of left ventricular wall motion using tagged MR images allows to characterize and follow-up changes of left ventricular wall motion in various diseases of the heart.

Aged↗

Persistent social dysfunction in anxious and depressed patients with personality disorder.

OBJECTIVE: To determine the long-term social function of psychiatric patients with anxiety and depressive disorders and to relate this to personality status and other factors. METHOD: A cohort of 210 patients (mean age 35 years) with dysthymic disorder, generalized anxiety disorder or panic disorder diagnosed using a structured interview (SCID) were assessed at baseline for personality status using the Personality Assessment Schedule (PAS) and ratings of anxiety and depression. Exactly 12 years later social function was assessed using the Social Functioning Questionnaire (SFQ) and personality reassessed with the PAS by a rater blind to initial personality status. Individual social function items were examined in those with and without personality disorders. RESULTS: Social function was significantly better in those with little or no baseline personality disturbance (P < 0.001) and the domains of close relationships, stress in completing tasks, use of spare time and family relationships showed the largest personality differences. A multiple linear regression model showed that self-rated depression scores, single marital status and personality status were the main baseline variables predicting social function at 12 years. CONCLUSION: Although personality characteristics may change over time social dysfunction persists and persistent social dysfunction in mental state disorders may be a strong indicator of personality disturbance rather than an indicator of treatment resistance.

Adult↗

Using patient-identifiable data for epidemiological research.

The use of patient-identifiable data in epidemiological research is subject to increasingly complex regulation. This article reports the experience of a research team in setting up the Epidemiology and Survival of Transfusion Recipients (EASTR) study in which patient-identifiable information was needed in order to link data from two sources for analysis and obtain long-term survival patterns of transfusion recipients. The process of establishing the study involved obtaining separate ethical, research and development and data protection approval, including application to the newly formed Patient Information Advisory Group, set up under Section 60 of the Health and Social Care Act, 2001. We describe the high cost in administrative procedures and time now necessary to gain statutory approval before such a study can begin, which has been the result of recent legislation. Issues arising from our experience are discussed.

Epidemiology↗