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Biomedical subjects

A Young

Publications and source records attributed to A Young.

At least 19 recordsLinked to original sources
PubMed2007

An in vitro study on the effect of TiF(4) treatment against erosion by hydrochloric acid on pellicle-covered enamel.

The aim of this in vitro study was to examine the effect of fluoride treatment on pellicle-covered enamel exposed to an acidic challenge simulating gastric reflux. Sixteen bovine and 16 human teeth were sectioned into four pieces, divided into four groups: (1) control, (2) 2-hour pellicle, (3) TiF(4), and (4) 2-hour pellicle + TiF(4), and subsequently subjected to 3 ml 0.01 M HCl stepwise for 4 + 4 + 4 min. The acid was analysed for calcium by atomic absorption spectroscopy. TiF(4) reduced Ca release from enamel by 76, 57 and 56% following the 4 + 4 + 4-min acid exposures, respectively, in bovine and 44, 54 and 54% in human enamel. These results suggest that treatment of enamel with a TiF(4) solution, with or without pellicle removal, may provide protection for the enamel against acid attack.

Animals↗
PubMed2006

The significance of the time interval between antecedent pregnancy and diagnosis of high-risk gestational trophoblastic tumours.

It is thought that the time interval between the antecedent pregnancy and diagnosis of gestational trophoblastic tumours (GTTs) may influence the outcome of these patients. In this study, we investigate the significance of this time interval. Multivariate analysis was used to investigate if the time interval was of prognostic significance from our cohort of 241 high-risk patients with GTT. Subsequent cutpoint analysis was used to determine an optimal cutpoint for the interval covariate. The outcome of these patients was plotted according to the Kaplan-Meier method. The time interval was of prognostic significance on multivariate analysis. A period of greater than 2.8 years after pregnancy was found to be of most significance. The 5-year overall survival was 62.0% (95% CI: 47-76%) for greater than 2.8 years vs 94% (95% CI: 91-97%) for less than 2.8 years (P<0.001). Multivariate analysis showed the presence of liver metastasis and the number of metastasis was also of prognostic importance. The interval between antecedent pregnancy and diagnosis in high-risk GTT is of prognostic significance. This gives some insight into the pathogenesis of the disease.

Adolescent↗
PubMed2006

A practical demonstration in modelling diclofenac and propranolol river water concentrations using a GIS hydrology model in a rural UK catchment.

An existing GIS hydrology water quality model, LF2000-WQX, was applied to predict the concentrations of the pharmaceuticals diclofenac and propranalol in catchments. As a practical exercise the predominantly rural Tamar (UK) catchment was chosen. Consumption, excretion, and fate data were used to estimate the pharmaceutical input load for the model. The predicted concentrations throughout most of the catchment were 1 ng/L or less under low flow (90th percentile) conditions. However, at a few locations, downstream of small sewage treatment plants, concentrations above 25 ng/L were predicted. This exercise shows that it is relatively straightforward to predict the concentrations of new and emerging organic microcontaminants in real catchments using existing GIS hydrology water quality models. Further testing will be required to establish their accuracy.

Computer Simulation↗
PubMed2006

Mortality in rheumatoid arthritis. Increased in the early course of disease, in ischaemic heart disease and in pulmonary fibrosis.

OBJECTIVE: To examine the cause of death in a large UK inception cohort of rheumatoid arthritis (RA), and whether this was related to disease duration and severity, treatment effects or extra-articular features and complications of RA. METHODS: Standard clinical, laboratory, radiological and socio-economic measures were recorded at baseline and yearly in an inception cohort started in nine centres in 1986. Date and the cause of death were based on death certificates and the comparisons made with age and sex matched population figures. Risk factors for mortality were identified from baseline measures of disease. RESULTS: There were 459 deaths (32%) in 1429 patients followed for up to 18 yrs. Standard mortality ratio was 1.27. Survival was significantly lower in the first 7 yrs of RA. Excess mortality was seen in cardiovascular disease (31%), pulmonary fibrosis (4%) and lymphoma (2.3%). Baseline predictors for mortality were men, older age, poor function, lower socio-economic status, extra-articular features, comorbidity, rheumatoid factor, X-ray erosions, high-ESR and low-haemoglobin. CONCLUSION: There was a modest increase in mortality in RA, mainly in the first 7 yrs. Deaths from cardiovascular disease and pulmonary fibrosis were higher than expected, but treatment-related deaths were low. Risk factors included less favourable socio-economic status, markers of disease severity and diminished function within the first year.

Age Factors↗
PubMed2006

Residual lung lesions after completion of chemotherapy for gestational trophoblastic neoplasia: should we operate?

The significance of residual lung metastasis from malignant gestational trophoblastic neoplasm (GTN) after the completion of chemotherapy is unknown. We currently do not advocate resection of these masses. Here, we investigate the outcome of these patients. Patients with residual lung abnormalities after the completion of treatment for GTN were compared to those who had a complete radiological resolution of the disease. None of the residual masses post-treatment were surgically removed. In all, 76 patients were identified. Overall 53 (70%) patients had no radiological abnormality on CXR or CT after completion of treatment. Eight (11%) patients had residual disease on CXR alone 15 patients had residual disease on CT (19%). During follow-up, two patients (2.6%) relapsed. One of these had had a complete radiological response post-treatment whereas the other had residual disease on CT. Patients with residual lung lesions after completing treatment for GTN do not appear to have an increased chance of relapse compared to those with no residual abnormality. We continue to recommend that these patients do not require pulmonary surgery for these lesions.

Adolescent↗
PubMed2006

Induction of decision trees using genetic programming for modelling ecotoxicity data: adaptive discretization of real-valued endpoints.

Recent literature has demonstrated the applicability of genetic programming to induction of decision trees for modelling toxicity endpoints. Compared with other decision tree induction techniques that are based upon recursive partitioning employing greedy searches to choose the best splitting attribute and value at each node that will necessarily miss regions of the search space, the genetic programming based approach can overcome the problem. However, the method still requires the discretization of the often continuous-valued toxicity endpoints prior to the tree induction. A novel extension of this method, YAdapt, is introduced in this work which models the original continuous endpoint by adaptively finding suitable ranges to describe the endpoints during the tree induction process, removing the need for discretization prior to tree induction and allowing the ordinal nature of the endpoint to be taken into account in the models built.

Decision Trees↗
PubMed2006

QSAR approach for mixture toxicity prediction using independent latent descriptors and fuzzy membership functions.

The principle of using a singe model to predict the toxicity of mixtures of chemicals based on the characterisation of the degrees of similarity and dissimilarity of the constituent chemicals using descriptors has been demonstrated in a previous work. The current study introduces a feature extraction technique, independent component analysis, to the method to remove the correlations and dependencies between descriptors and reduce the dimension prior to similarity and dissimilarity calculations. In addition, a goal attainment multi-objective optimisation technique is used for the determination of the fuzzy membership function parameters. For three mixtures, which include a new mixture and two previously studied mixtures that all inhibit reproduction (via different mechanisms of action) in green freshwater algae scenedesmus vacuolatus, the approach showed better or equivalent prediction performance than either concentration addition or independent action models. Unlike QSARs for pure compounds that require large collections of data, the new approach for mixtures only requires one mixture at a particular composition to determine the necessary fuzzy membership function parameter values. These values can then be used to predict the toxicity of the mixture at any other compositions. This could potentially lead to a reduction in the frequency of bioassay tests. Use of the fuzzy membership functions and parameter values obtained for one mixture when used to predict the toxicity of a completely different mixture is also tested and it is found that the approach also gives prediction results with good accuracy.

Chlorophyta↗
PubMed2006

Two sporadic cases of adult-onset progressive mucinous histiocytosis.

Progressive mucinous histiocytosis is a rare, benign, non-Langerhans' cell histiocytosis limited to the skin. Ten cases--all women--in four families and one sporadic case have been described in the literature. The disorder usually begins in childhood and progresses slowly. We report two sporadic cases of adult-onset progressive mucinous histiocytosis in unrelated African-American women, aged 48 and 55 years, respectively, who developed red-brown and flesh-coloured, asymptomatic papules on the face, the arms and the legs without truncal, mucosal or visceral involvement. The lesions showed no spontaneous regression. Both patients lacked associated systemic symptoms, including polyuria, polydipsia or seizures. There was no underlying hyperlipidaemia, paraproteinaemia or lymphoproliferative disease. No family history of similar lesions could be identified. Light microscopy revealed dermal proliferation of spindle-shaped histiocytes with abundant mucin deposition. Electron microscopy demonstrated a high number of myelin figures or zebra bodies in the cytoplasm of histiocytes. On immunohistochemistry, positive staining with macrophage markers--CD68, HAM56 and lysozyme--and factor XIIIa, a transglutaminase present in dermal dendrocytes, and negative staining with Langerhans' cell markers--CD1a and S100--and CD34, a marker present in dermal dendritic cells derived from uncommitted mesenchymal cells, were observed.

Diagnosis, Differential↗
PubMed2006

Deaf children identified through newborn hearing screening: parents' experiences of the diagnostic process.

BACKGROUND: As part of the Department of Health funded evaluation of the first phase of the National Health Service Newborn Hearing Screening Programme in England, 45 parents/caregivers whose children were correctly identified as deaf through the screening programme were interviewed about their experiences. METHODS: The study took a qualitative descriptive approach and thus sought to privilege parents' unique epistemological position, valuing their accounts as expert knowledge and allowing them to set the criteria for what should be counted as meaningful within their accounts. The sample of 45 parents/caregivers was diverse in terms of ethnicity and socio-economic status. In addition, the children represented a diversity of degrees of deafness and additional needs. Data were analysed using QSR NUD*IST 4. RESULTS: The diagnostic period emerged as an important time for parents. This refers to the period of time that follows the referral from screen and starts with the first appointment at audiology for audiological assessment. The diagnostic process was found to be hugely variable for each family, both objectively, e.g. in terms of number of appointments they had to attend, and also attitudinally, e.g. some families perceived this period of time as a series of discrete events while others viewed it as part of a process that had started with the first screening event. Although it is reasonable to expect such factors to be the most influential in accounting for variations in parental satisfaction with the diagnostic process, it was in fact professional communication and manner that emerged as the most significant predictors of their experiences. DISCUSSION: The discussion concentrates on the question of whether early identification of deafness and the subsequent compressed time frame of events between birth and diagnosis create "new" experiences for parents or whether in fact the new circumstances surrounding diagnosis make no difference to the way in which professionals approach their encounters with parents.

Attitude to Health↗
PubMed2006

Marijuana lung.

Explore the source record for details and available documents.

Adult↗
PubMed2005

Rehospitalization following compensable work-related tetraplegia.

DESIGN: Descriptive study. OBJECTIVES: To document the characteristics of rehospitalization following work-related tetraplegia, investigate risk factors for rehospitalization and identify opportunities for rehospitalization prevention. SETTING: Workers' compensation administrative database with national coverage. METHODS: The administrative database of a large workers' compensation provider was searched for work-related tetraplegia claims with dates of injury between 1 January 1989 and 31 December 1999. In all, 61 cases were identified where detailed rehospitalization information was available. Medical payment data were extracted, rehospitalization reasons were coded, and rates, costs and length of stay were calculated. RESULTS: In all, 62% of cases were rehospitalized at some time during the period for which data were available. The average number of days the study group spent rehospitalized per year was 9.2 and the average annual cost was 14,197 US dollars. The most common reasons for rehospitalization were dermatological (23%), orthopedic (18%) and urological (14%). It was found that as many as 74% of the total number of days persons spent rehospitalized, 64% of the monies spent on rehospitalization, and 47% of rehospitalizations could have been prevented. CONCLUSIONS: Consistent with earlier research, the ability to identify risk factors for rehospitalization was limited. However, the current study does highlight the extent to which rehospitalizations disrupt the lives of people with work-related tetraplegia and that a substantial proportion of rehospitalizations can be avoided. SPONSORSHIP: The research was supported, in part, by a grant from the National Institute on Disability and Rehabilitation Research National Model SCI Systems (Grant no. H133N00024).

Adult↗
PubMed2005

A phase I study of antisense oligonucleotide GTI-2040 given by continuous intravenous infusion in patients with advanced solid tumors.

BACKGROUND: This study of GTI-2040, a 20-mer phosphorothioate oligonucleotide complementary to the messenger ribonucleic acid (mRNA) of the R2 subunit of ribonucleotide reductase (RNR), was conducted to determine the dose-limiting toxicity (DLT) and maximum-tolerated dose (MTD) of the agent in patients with advanced solid tumors or lymphoma. Plasma pharmacokinetics of GTI-2040 and suppression of RNR expression in peripheral blood mononuclear cells were also studied. PATIENTS AND METHODS: GTI-2040 was administered as a continuous intravenous infusion for 21 days every 4 weeks. Dose escalation was performed using an accelerated, dose-doubling schedule until any drug related toxicity > or = grade 2 was observed; subsequent dose escalation followed a more conservative dose escalation scheme with three patients/cohort. RESULTS: A total of 49 cycles of therapy were administered to 36 patients at GTI-2040 doses ranging from 18.5 mg/m(2)/day to 222 mg/m(2)/day. GTI-2040 was generally well tolerated. At the highest dose level examined, two patients experienced dose limiting reversible hepatic toxicity. Constitutional toxicities consisting of fatigue and anorexia were the most common toxicities. CONCLUSIONS: The recommended dose of GTI-2040 given on this infusion schedule is 185 mg/m(2)/day. GTI-2040 appears to have a manageable toxicity profile and is generally well tolerated as a single agent.

Adult↗
PubMed2005

Utilisation of a cryptic non-canonical donor splice site of the gene encoding PARAFIBROMIN is associated with familial isolated primary hyperparathyroidism.

More than 99% of all splice sites conform to consensus sequences that usually include the invariant dinucleotides gt and ag at the 5' and 3' ends of the introns, respectively. We report on the utilisation of a non-consensus (non-canonical) donor splice site within exon 1 of the HRPT2 gene in familial isolated primary hyperparathyroidism (FIHP). HRPT2 mutations are more frequently associated with the hyperparathyroidism-jaw tumour syndrome (HPT-JT). Patients with FIHP were identified to have a donor splice site mutation, IVS1+1 g-->a, and the consequences of this for RNA processing were investigated. The mutant mRNA lacked 30 bp and DNA sequence analysis revealed this to result from utilisation of an alternative cryptic non-canonical donor splice site (gaatgt) in exon 1 together with the normally occurring acceptor splice site in intron 1. Translation of this mutant mRNA predicted the in-frame loss of 10 amino acids in the encoded protein, termed PARAFIBROMIN. Thus, these FIHP patients are utilising a ga-ag splice site pair, which until recently was considered to be incompatible with splicing but is now known to occur as a rare (<0.02%) normal splicing variant.

Adult↗
PubMed2004

OntologyTraverser: an R package for GO analysis.

UNLABELLED: Gene Ontology (GO) annotations have become a major tool for analysis of genome-scale experiments. We have created OntologyTraverser--an R package for GO analysis of gene lists. Our system is a major advance over previous work because (1) the system can be installed as an R package, (2) the system uses Java to instantiate the GO structure and the SJava system to integrate R and Java and (3) the system is also deployed as a publicly available web tool. AVAILABILITY: Our software is academically available through http://franklin.imgen.bcm.tmc.edu/OntologyTraverser/. Both the R package and the web tool are accessible. CONTACT: cashaw@bcm.tmc.edu

Algorithms↗
PubMed2004

Achievement of ultralow emittance beam in the accelerator test facility damping ring.

For high luminosity in electron-positron linear colliders, it is essential to generate low vertical emittance beams. We report on the smallest vertical emittance achieved in single-bunch-mode operation of the Accelerator Test Facility, which satisfies the requirement of the x-band linear collider. The emittances were measured with a laser-wire beam-profile monitor installed in the damping ring. The bunch length and the momentum spread of the beam were also recorded under the same conditions. The smallest vertical rms emittance measured at low intensity is 4 pm at a beam energy of 1.3 GeV, which corresponds to the normalized emittance of 1.0x1.0(-8) m. It increases by a factor of 1.5 for a bunch intensity of 10(10) electrons. The measured data agreed to the calculation of intrabeam scattering within much better than a factor of 2.

Journal Article↗