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Biomedical subjects

J Doyle

Publications and source records attributed to J Doyle.

At least 19 recordsLinked to original sources
PubMed2006

The influence of capsule geometry and cement formulation on the apparent viscosity of dental cements.

OBJECTIVES: This work examines the influence of specific aspects of capsule design and cement formulation on the handling properties of the extruded glass polyalkenoate cement (GPC) pastes. METHODS: A commercial metal reinforced GPC, HiDense, and experimental GPCs were extruded using a tensometer at loads and rates maintained within end-user limits and the apparent viscosity of the cement paste was determined by applying Poiseuille's law. The influence of the extrusion procedure (mixing time and ram speed), capillary geometry (length and diameter) and cement composition (powder: liquid (P:L) ratio, tartaric acid content and poly(acrylic acid) molar mass) on the apparent viscosity of the cement paste was evaluated. RESULTS: The examined GPCs behaved as non-Newtonian, pseudoplastic materials and exhibited a yield stress. Variation of the geometry of the capsule capillary resulted in the apparent viscosity of HiDense increasing by 7% as the length increased from 5 to 15mm whilst halving the capillary diameter from 2 to 1mm resulted in a 63% decrease in the apparent viscosity and a 600% increase in the extrusion load. The apparent viscosity of the experimental GPCs was increased by an increase in the P:L ratio and, in general, by the PAA molar mass, whilst the concentration-dependent effect of (+)-tartaric acid (TAA) indicates a working time dependence on TAA content. CONCLUSIONS: Using this approach optimisation of the rheological properties can be achieved by manipulation of the capsule design and cement formulation due to the dependency of the apparent viscosity on the capillary diameter, TAA content, P:L ratio and poly(acrylic acid) molar mass.

Chemistry, Pharmaceutical↗
PubMed2006

Vitamin K deficiency in children pre-bone marrow transplantation.

This study examined the prevalence of vitamin K deficiency in children pre-bone marrow transplantation (BMT). Vitamin K status was measured by the PIVKA-II assay and prothrombin times. Blood samples were obtained before vitamin-containing TPN was infused. Results indicated that eight of 26 patients (31%) were vitamin K deficient; four cases were attributed to drug antagonism (phenytoin) and four were due to inadequate vitamin K intake, synthesis or malabsorption. Only one patient had a prolonged prothrombin time. Prothrombin time, in our study, is shown to be an ineffective screening tool to determine vitamin K status. All patients receiving phenytoin and chemotherapy are at increased risk of vitamin K deficiency.

Adolescent↗
PubMed2006

Dilation as treatment for vaginal agenesis and hypoplasia: a pilot exploration of benefits and barriers as perceived by patients.

Reconstructive surgery has been the traditional treatment for the short vagina. Recently vaginal dilation has been recommended due to its low morbidity. Small retrospective studies have reported success rates of up to 80% but include neither clear definitions of "success" nor exploration of factors associated with compliance and outcome. The first 10 women prescribed vaginal dilation treatment at a specialist gynaecological clinic during the study period were interviewed and asked to complete the Multi-dimensional Sexuality Questionnaire (MSQ), with an assessment of perceived vaginal characteristics. The participants scored lower scores on sexual esteem, sexual assertiveness and sexual satisfaction and higher scores in sexual anxiety, sexual depression and fear of sexual relationships in comparison with the standardisation sample. Dilator treatment must be subject to the same scrutiny as any intervention. Vaginal dilation can have a negative emotional impact on women and psychological intervention may be needed to maximise efficacy.

Adolescent↗
PubMed2005

Highly optimized tolerance and power laws in dense and sparse resource regimes.

Power law cumulative frequency (P) versus event size (l) distributions P > or =l) approximately l(-alpha) are frequently cited as evidence for complexity and serve as a starting point for linking theoretical models and mechanisms with observed data. Systems exhibiting this behavior present fundamental mathematical challenges in probability and statistics. The broad span of length and time scales associated with heavy tailed processes often require special sensitivity to distinctions between discrete and continuous phenomena. A discrete highly optimized tolerance (HOT) model, referred to as the probability, loss, resource (PLR) model, gives the exponent alpha=1/d as a function of the dimension d of the underlying substrate in the sparse resource regime. This agrees well with data for wildfires, web file sizes, and electric power outages. However, another HOT model, based on a continuous (dense) distribution of resources, predicts alpha=1+1/d . In this paper we describe and analyze a third model, the cuts model, which exhibits both behaviors but in different regimes. We use the cuts model to show all three models agree in the dense resource limit. In the sparse resource regime, the continuum model breaks down, but in this case, the cuts and PLR models are described by the same exponent.

Journal Article↗
PubMed2005

Reproducibilty of partial weight bearing.

OBJECTIVES: To find out whether partial weight bearing can be reproduced and retained. DESIGN: In vivo experiment in normal subjects. INTERVENTION: Training for partial weight bearing (25% of body weight) using bathroom scales. MAIN OUTCOME MEASUREMENT: Reproducibility on force platform immediately after training and after 60 min. RESULTS: Twelve subjects were asked to reproduce 25% of their body weight through either the dominant or non-dominant limb on force platform after three practice attempts on bathroom scales with concurrent visual feedback. No feedback was provided after the measurements on force plate. The process was repeated after 1h without any practice sessions in the interim period to find out if the weight practised could be retained. The mean 0-min reading was found to be 25.9% of body weight while the mean 60-min reading was found to be 24.4%. The p-value for the difference between the two means was found to be 0.3841. CONCLUSIONS: This study indicates that partial weight bearing instructions can be quantified and graded. Simple bathroom scales are sufficient to educate the patients and this can be practised at home after an initial period of supervision.

Adult↗
PubMed2005

Highly optimised global organisation of metabolic networks.

High-level, mathematically precise descriptions of the global organisation of complex metabolic networks are necessary for understanding the global structure of metabolic networks, the interpretation and integration of large amounts of biologic data (sequences, various -omics) and ultimately for rational design of therapies for disease processes. Metabolic networks are highly organised to execute their function efficiently while tolerating wide variation in their environment. These networks are constrained by physical requirements (e.g. conservation of energy, redox and small moieties) but are also remarkably robust and evolvable. The authors use well-known features of the stoichiometry of bacterial metabolic networks to demonstrate how network architecture facilitates such capabilities, and to develop a minimal abstract metabolism which incorporates the known features of the stoichiometry and respects the constraints on enzymes and reactions. This model shows that the essential functionality and constraints drive the tradeoffs between robustness and fragility, as well as the large-scale structure and organisation of the whole network, particularly high variability. The authors emphasise how domain-specific constraints and tradeoffs imposed by the environment are important factors in shaping stoichiometry. Importantly, the consequence of these highly organised tradeoffs and tolerances is an architecture that has a highly structured modularity that is self-dissimilar and scale-rich.

Animals↗
PubMed2005

Global priority setting for Cochrane systematic reviews of health promotion and public health research.

BACKGROUND: Systematic reviews of health promotion and public health interventions are increasingly being conducted to assist public policy decision making. Many intra-country initiatives have been established to conduct systematic reviews in their relevant public health areas. The Cochrane Collaboration, an international organisation established to conduct and publish systematic reviews of healthcare interventions, is committed to high quality reviews that are regularly updated, published electronically, and meeting the needs of the consumers. AIMS: To identify global priorities for Cochrane systematic reviews of public health topics. METHODS: Systematic reviews of public health interventions were identified and mapped against global health risks. Global health organisations were engaged and nominated policy-urgent titles, evidence based selection criteria were applied to set priorities. RESULTS: 26 priority systematic review titles were identified, addressing interventions such as community building activities, pre-natal and early infancy psychosocial outcomes, and improving the nutrition status of refugee and displaced populations. DISCUSSION: The 26 priority titles provide an opportunity for potential reviewers and indeed, the Cochrane Collaboration as a whole, to address the previously unmet needs of global health policy and research agencies.

Evidence-Based Medicine↗
PubMed2004

Allogeneic bone marrow transplantation vs chemotherapy for children with Philadelphia chromosome-positive acute lymphoblastic leukemia.

Allogeneic bone marrow transplant (BMT) with an MRD in complete remission (CR)1 is the preferred treatment for children with Philadelphia-positive (Ph(+)) ALL. The role of MUD BMT in CR1 is still controversial. We compared the outcomes of two treatment strategies: BMT using an MRD or MUD vs chemotherapy in children with Ph(+) ALL in CR1. In total, 21 children were treated from 1985 to 2001. In all, 10 received chemotherapy and 11 received allogeneic BMT: four MRD, seven MUD. In the MRD group, one relapsed 12 months after BMT and died; the remaining three are long-term event-free survivors (median follow-up, 6.1 years). In the MUD group four died; the remaining three are long-term event-free survivors (median follow-up, 7.2 years). The 4-year event-free survival (EFS) for the BMT group was 53+/-15%. In the chemotherapy group, seven relapsed after a median period of 12.5 months and three remain in continuous CR (median follow-up, 2.4 years). Four chemotherapy patients received CR2 transplants; all died. The 4-year EFS for the chemotherapy and MUD groups was 33+/-17 and 35.7+/-20%, respectively. This difference was not statistically significant. We continue to support treating children with Ph(+) ALL with MRD BMT in CR1. The effectiveness of MUD BMT vs chemotherapy merits further study.

Adolescent↗
PubMed2004

Surface diagnostics for scale analysis.

Stainless steel, polymethylmethacrylate and polytetrafluoroethylene coupons were analysed for surface topographical and adhesion force characteristics using tapping mode atomic force microscopy and force-distance microscopy techniques. The two polymer materials were surface modified by polishing with silicon carbide papers of known grade. The struvite scaling rate was determined for each coupon and related to the data gained from the surface analysis. The scaling rate correlated well with adhesion force measurements indicating that lower energy materials scale at a lower rate. The techniques outlined in the paper provide a method for the rapid screening of materials in potential scaling applications.

Chemical Precipitation↗
PubMed2003

Familial cryptic translocation (2;17) ascertained through recurrent spontaneous abortions.

We report a young woman who presented with a reproductive history of three recurrent spontaneous abortions (RSA) and two neonatal deaths. Comparative genomic hybridization (CGH) was used to determine the chromosomal composition of the patient's last miscarriage. It showed the presence of monosomy for the distal end of chromosome 2 long arm (segment 2q37.2 to qter) and trisomy for the distal end of chromosome 17 long arm (segment 17q25 to qter). The mother was found to be a carrier for a cryptic translocation between chromosomes 2 and 17 long arms by fluorescence in situ hybridization using a subtelomeric probe for 17q. Retrospective CGH analysis on one baby who died neonatally showed that he had inherited the maternal translocation in the same unbalanced state as the last pregnancy loss. His detailed postmortem examination is reported.

Abortion, Habitual↗
PubMed2002

Device for accurately siting the acetabular component during total hip replacement.

INTRODUCTION: In this paper we describe a device which allows consistent acetabular cup placement to reduce post-arthroplasty dislocation. PATIENTS AND METHODS: The development of this surgical appliance is traced from the initial concept to the construction of a device suitable for clinical trials. The system of use is explained. The constraints imposed by the working environment and the methods employed to meet the demands imposed by surgical practice are elucidated. A clinical trial is described in which the device was used to assist in siting acetabular cup placement in ten patients. RESULTS: The accuracy of the ten cup placements done using the device was then compared by radiography with the accuracy of placement of 17 acetabular cups performed in the standard manner. Comparison of the results show a positive benefit arising from using the device. CONCLUSIONS: Our initial good results on cup positioning in laboratory studies are maintained in a clinical setting, but further modifications could lend to even better results.

Acetabulum↗
PubMed2002

Evidence-based public health practice: improving the quality and quantity of the evidence.

Evidence-based practice in public health has moved from being a complex cousin of evidence-based medicine to a field that is seeking to establish how evidence-based principles can apply to public health approaches. The Cochrane Collaboration Health Promotion and Public Health field offers public health practitioners the opportunity to be involved in these developments, and/or to employ the array of relevant systematic reviews in their practice.

Evidence-Based Medicine↗
PubMed2002

The ERATO Systems Biology Workbench: enabling interaction and exchange between software tools for computational biology.

Researchers in computational biology today make use of a large number of different software packages for modeling, analysis, and data manipulation and visualization. In this paper, we describe the ERATO Systems Biology Workbench (SBW), a software framework that allows these heterogeneous application components--written in diverse programming languages and running on different platforms--to communicate and use each others' data and algorithmic capabilities. Our goal is to create a simple, open-source software infrastructure which is effective, easy to implement and easy to understand. SBW uses a broker-based architecture and enables applications (potentially running on separate, distributed computers) to communicate via a simple network protocol. The interfaces to the system are encapsulated in client-side libraries that we provide for different programming languages. We describe the SBW architecture and the current set of modules, as well as alternative implementation technologies.

Computational Biology↗
PubMed2001

Atomic-beam alignment of inorganic materials for liquid-crystal displays.

The technique used to align liquid crystals-rubbing the surface of a substrate on which a liquid crystal is subsequently deposited-has been perfected by the multibillion-dollar liquid-crystal display industry. However, it is widely recognized that a non-contact alignment technique would be highly desirable for future generations of large, high-resolution liquid-crystal displays. A number of alternative alignment techniques have been reported, but none of these have so far been implemented in large-scale manufacturing. Here, we report a non-contact alignment process, which uses low-energy ion beams impinging at a glancing angle on amorphous inorganic films, such as diamond-like carbon. Using this approach, we have produced both laptop and desktop displays in pilot-line manufacturing, and found that displays of higher quality and reliability could be made at a lower cost than the rubbing technique. The mechanism of alignment is explained by adopting a random network model of atomic arrangement in the inorganic films. Order is induced by exposure to an ion beam because unfavourably oriented rings of atoms are selectively destroyed. The planes of the remaining rings are predominantly parallel to the direction of the ion beam.

Journal Article↗