PubMed Health⌕ Search

Biomedical subjects

Christine Williams

Publications and source records attributed to Christine Williams.

17 recordsLinked to original sources
PubMed2006

Early evaluation of compound QT prolongation effects: a predictive 384-well fluorescence polarization binding assay for measuring hERG blockade.

INTRODUCTION: A large number of drugs from a variety of pharmacological classes have been demonstrated to cause adverse effects on cardiac rhythm, including the life-threatening arrhythmia Torsades de Pointes. These side effects are often associated with prolongation of the QT interval and are mediated via blockade of the human ether-a-go-go related gene (hERG) encoded potassium channel. In order to manage this risk in the pharmaceutical industry it is desirable to evaluate QT prolongation as early as possible in the drug discovery process. METHODS: Here we describe the development of a 384-well fluorescence polarization (FP) binding assay compatible with high-throughput assessment of compound blockade of the hERG channel during the lead optimisation process. To characterise the fluorescent ligand that was developed, competition binding studies, kinetic studies and electrophysiology studies were performed. Furthermore, to validate the assay as a key screening method a series of competition binding studies were performed and correlated with functional data obtained via patch-clamp. RESULTS: Evaluation of the assay indicates that high quality data is obtained (Z'>0.6), that the K(i) values determined are equivalent to more traditional radiometric methods and that it is predictive for functional hERG blockade as assessed by patch clamp. DISCUSSION: Whilst FP assays, utilizing a variety of fluors, have become well established for the evaluation of G-protein-coupled receptor (GPCRs) and kinase ligand interactions, this technique has not been applied widely to the study of ion channels. Therefore, this represents a novel assay format that is amenable to the evaluation of thousands of compounds per day. Whilst other assay formats have proven predictive or high throughput, this assay represents one of few that combines both attributes, moreover it represents the most cost effective assay, making it truly amenable to early assessment of hERG blockade.

Binding, Competitive↗
PubMed2006

The relation of education and gender on the attention items of the Mini-Mental State Examination in Spanish speaking Hispanic elders.

The Mini-Mental State Examination (MMSE) [Folstein, M. F., Folstein, S. E., & McHugh, P. R. (1975). Mini-Mental State: A practical method for grading the cognitive state of patients for the clinician. Journal of Psychiatric Research, 12, 189-198] has frequently been challenged for its bias against individuals with lower levels of education and the use of scoring adjustments for lower educational levels has become standard practice [Ostrosky-Solis, F., Lopez-Arango, G., & Ardila, A. (2000). Sensitivity and specificity of the Mini Mental State Examination in a Spanish-speaking population. Applied Neuropsychology, 7, 25-31]. An additional source of concern is that original instructions specify that the "serial 7's" item may be replaced by an apparently less difficult "backwards spelling" task. This study compared the performance on these items and the effects for total scores on 102 unimpaired and 58 memory impaired elder Hispanic individuals (age 54-98), divided into 3 groups based on educational level (<7, 7-11, and >11 years of education). The effects of education and gender on the total MMSE scores were analyzed using the "serial 7's" and the "backwards spelling" items. For all the studied groups, MMSE scores were higher by an average of 1.5 points when using the "backwards spelling" task. Correlation between "serial 7's" and "backwards spelling" was a modest .37. Education had a significant effect on the MMSE scores in both the impaired and the unimpaired groups. After controlling for education, gender also explains a significant proportion of the variance of the results. The "backwards spelling" and "serial 7's" items do not appear to be either equivalent in difficulty or to test the same abilities in the unimpaired and the impaired Hispanics elders tested in this study.

Aged↗
PubMed2006

Patterns of reading ability in children with autism spectrum disorder.

This study investigated reading skills in 41 children with autism spectrum disorder. Four components of reading skill were assessed: word recognition, nonword decoding, text reading accuracy and text comprehension. Overall, levels of word and nonword reading and text reading accuracy fell within average range although reading comprehension was impaired. However, there was considerable variability across the sample with performance on most tests ranging from floor to ceiling levels. Some children read accurately but showed very poor comprehension, consistent with a hyperlexia reading profile; some children were poor at reading words and nonwords whereas others were unable to decode nonwords, despite a reasonable level of word reading skill. These findings demonstrate the heterogeneous nature of reading skills in children with ASD.

Adolescent↗
PubMed2006

Roles for Dnmt3b in mammalian development: a mouse model for the ICF syndrome.

ICF (Immunodeficiency, Centromeric instability and Facial anomalies) syndrome is a rare autosomal recessive disease caused by mutations in the DNA methyltransferase gene DNMT3B. To investigate the function of Dnmt3b in mouse development and to create animal models for ICF syndrome, we have generated three mutant alleles of Dnmt3b in mice: one carrying a deletion of the catalytic domain (null allele) and two carrying ICF-like missense mutations in the catalytic domain. The Dnmt3b null allele results in embryonic lethality from E14.5 to E16.5 with multiple tissue defects, including liver hypotrophy, ventricular septal defect and haemorrhage. By contrast, mice homozygous for the ICF mutations develop to term and some survive to adulthood. These mice show phenotypes that are reminiscent of ICF patients, including hypomethylation of repetitive sequences, low body weight, distinct cranial facial anomalies and T cell death by apoptosis. These results indicate that Dnmt3b plays an essential role at different stages of mouse development, and that ICF missense mutations cause partial loss of function. These mutant mice will be useful for further elucidation of the pathogenic and molecular mechanisms underlying ICF syndrome.

Animals↗
PubMed2006

The educational impact of a computer-based training tutorial on dementia in long term care for licensed practice nursing students.

The purpose of this study was to examine whether training with a multimedia tutorial would have an impact on LPN students' knowledge of dementia care, attitudes toward dementia care, and self-efficacy ratings. A total of 38 nursing students participated. Pre-post comparisons of outcome measures revealed significant improvements in knowledge, attitudes, and self-efficacy ratings. Results of post-training satisfaction and usability questionnaires indicate that participants found the tutorials easy to understand and easy to use. These data support the effectiveness of the dementia tutorial and the use of computer-based training in educating our long-term care workforce.

Adult↗
PubMed2005

Improving the design and analysis of high-throughput screening technology comparison experiments using statistical modeling.

Contemporary small-molecule drug discovery frequently involves the screening of large compound files as a core activity. Subsequently cost, speed, and safety become critical issues. In order to meet this need, numerous technologies have been developed to allow mix and measure approaches, facilitate miniaturization, and to increase speed and to minimize the use of potentially hazardous reagents such as radioactive materials. However, despite the on-paper advantages of these new technologies, risks can remain undefined. For example, the question of whether the novel method will facilitate identification of active chemical series in a way that is comparable with conventional methods arises. In order to address this question, we have taken the approach of carrying out experiments to directly compare the output of high-throughput screens using a given novel approach and a traditional method. The concordance between the screening methods can then be determined via comparison of the numbers and structures of the active molecules identified. This article describes the approach taken in our laboratory to minimize variability in such experiments and shows data that exemplifies the general result of lower than expected concordance. Statistical modeling was subsequently used to facilitate this interpretation. The model used beta-distribution function to generate a real-activity frequency relationship with added normal random error and occasional outliers to represent assay variability. Hence, the effect of assay parameters such as the threshold, the number of real actives, and the number of outliers and the standard deviation could readily be explored. The model was found to describe the data reasonably and moreover was found to be of great utility when it came to planning further optimal experiments. A key conclusion from the model was that concordance between screening methods could appear poor even when one approach is compared with itself. This occurs simply because the result is a function of assay threshold, standard deviation and the true compound % activity. In response to this finding we have adopted alternative experimental designs that more reliably measure the concordance between screening methods.

Biological Assay↗
PubMed2005

Targeted deletion of integrin-linked kinase reveals a role in T-cell chemotaxis and survival.

Integrin-linked kinase (ILK) is a serine/threonine kinase that is important in cell-matrix interactions and cell signaling. To examine the role of ILK in leukocyte trafficking and survival, we generated T cell-specific ILK knockouts by breeding ILK(flox/flox) mice to transgenic mice expressing Cre recombinase under control of the Lck proximal promoter. Thymic T cells from Lck-Cre(+)/ILK(flox/flox) mice had a marked reduction (>95%) in ILK protein levels. Thymic cellularity was comparable in 3- to 4-week-old mice, but a threefold diminution of thymic T cells became evident by 6 to 8 weeks of age in the T cell-specific ILK knockout mice due to increased cell death of double-positive (DP) T cells. Analysis of peripheral T cells by quantitative PCR and by breeding Lck-Cre(+)/ILK(flox/flox) mice to a YFP-transgenic reporter strain demonstrated an approximate 20-fold enrichment of ILK-competent cells, suggesting these cells have a competitive advantage in trafficking to and/or survival in peripheral lymphatic organs. We explored mechanisms related to altered cell trafficking and survival that might explain the decreases in thymic cellularity and enrichment for ILK-competent cells in the spleen and lymph nodes. We observed a >50% reduction in chemotaxis of ILK-deficient T cells to the chemokines CXCL12 (stromal cell-derived factor [SDF]-1alpha) and CCL19 (macrophage inflammatory protein [MIP]-3beta), as well as enhanced apoptosis of ILK-deficient cells upon stress. Signaling studies in ILK-deficient T cells demonstrated diminished phosphorylation of Akt on the activating phosphorylation site, Ser 473, and a concordant decrease in Akt kinase activity following stimulation with the chemokine SDF-1. Rac1 activation was also markedly diminished in ILK-deficient T cells following chemokine stimulation. These data extend the role of ILK to immune-cell trafficking and survival via modulation of Akt- and Rac-dependent substrates, and have implications for cell recruitment in both homeostatic and pathological processes.

Animals↗
PubMed2004

cAMP detection methods in HTS: selecting the best from the rest.

The number of technologies that enable high-throughput functional screening of G-protein-coupled receptors has expanded markedly over the past 5 years. Consequently, choosing the most appropriate technology can be a daunting task, particularly for Gi- or Gs-coupled receptors. The most common systems for cyclic AMP detection are reviewed, highlighting the practical and theoretical aspects that are important in their application to high-throughput screening. Current technologies can do the job, but it is likely that the future may require development of technologies that provide even greater biological information.

Animals↗
PubMed2004

Development and automation of a 384-well cell fusion assay to identify inhibitors of CCR5/CD4-mediated HIV virus entry.

This article describes the automation of an in vitro cell-based fusion assay for the identification of novel inhibitors of receptor mediated HIV-1 entry. The assay utilises two stable cell lines: one expressing CD4, CCR5 and an LTR-promoter/beta-galactosidase reporter construct, and the other expressing gp160 and tat. Accumulation of beta-galactosidase can only occur following fusion of these two cell lines via the gp160 and receptor mediators, as this event facilitates the transfer of the tat transcription factor between the two cell types. Although similar cell fusion systems have been described previously, they have not met the requirements for HTS due to complexity, throughput and reagent cost. The assay described in this article provides significant advantage, as (a) no transfection/infection events are required prior to the assay, reducing the potential for variability, (b) cells are mixed in solution, enhancing fusion efficiency compared to adherent cells, (c) miniaturization to low volume enables screening in 384-well plates; and (d) online cell dispensing facilitates automated screening. This assay has been employed to screen approximately 650,000 compounds in a singleton format. The data demonstrate that the assay is robust, with a Z' consistently above 0.6, which compares favourably with less complex biochemical assays.

Animals↗
PubMed2004

The experience of time in the transition from hospital to home following stroke.

This paper reports findings related to the transition from hospital to home during the first month after discharge following acute stroke. Qualitative data were obtained from in-depth, semistructured interviews with 51 male stroke survivors and their caregivers. Data were analyzed with the N6 software application, designed to assist with qualitative data analysis. Stroke survivors described experiences related to changes in the temporal order of life, disruptions in sense of self, and strategies used to manage time. Findings indicate that changes in the temporal order of life are related to functional impairments and disruption in the taken-for-granted body. At 1 month post-discharge, survivors are struggling with establishing routines in their day and coping with an increased amount of idle time. In conclusion, strategies for managing increased idle time are "passing time," "waiting on time," and "killing time."

Adaptation, Psychological↗
PubMed2004

Preventing 3 million premature deaths and helping 5 million smokers quit: a national action plan for tobacco cessation.

In August 2002, the Subcommittee on Cessation of the Interagency Committee on Smoking and Health (ICSH) was charged with developing recommendations to substantially increase rates of tobacco cessation in the United States. The subcommittee's report, A National Action Plan for Tobacco Cessation, outlines 10 recommendations for reducing premature morbidity and mortality by helping millions of Americans stop using tobacco. The plan includes both evidence-based, population-wide strategies designed to promote cessation (e.g., a national quitline network) and a Smokers' Health Fund to finance the programs (through a 2 US dollar per pack excise tax increase). The subcommittee report was presented to the ICSH (February 11, 2003), which unanimously endorsed sending it to Secretary Thompson for his consideration. In this article, we summarize the national action plan.

Cause of Death↗
PubMed2004

Impact of lower urinary tract symptoms on quality of life and sexual function.

Patients with lower urinary tract symptoms may also experience sexual dysfunction, but are reluctant to discuss this with a health-care professional. Nurses who assess these patients have a responsibility to offer non-judgemental support. The investigations and treatment options available are discussed in this article.

Aged↗
PubMed2003

Benchmarking as everyday functional assessment in stroke recovery.

OBJECTIVES: Functional assessment in stroke recovery extends beyond formal testing and evaluation. Stroke survivors themselves continuously engage in the process of reckoning their functional capacities as they go about their everyday lives. This process is called benchmarking. The aim of this article is to discuss and illustrate how it operates in three areas of experience--self-definition, comorbidity and age, and the tasks of daily life. METHODS: Benchmarking data are drawn from in-depth qualitative interviews with male stroke survivors of various ages and from three ethnic groups (Hispanic, African American, and non-Hispanic White). RESULTS: The results show that the benchmarking process is evident in all social categories in which survivors fall, but specific kinds of benchmarks may be more prominent in some categories than others. DISCUSSION: The lessons provided by everyday functional assessment for understanding the stroke experience, as well as directions for further study, are discussed in the conclusion.

Activities of Daily Living↗
PubMed2003

Measuring intracellular calcium fluxes in high throughput mode.

The measurement of intracellular calcium fluxes in real time is widely applied within the pharmaceutical industry to measure the activation of G-protein coupled receptors (GPCRhyp;s), either for pharmacological characterisation or to screen for new surrogate ligands. Initially restricted to G(q) coupled GPCRs, the introduction of promiscuous and chimeric G-proteins has further widened the application of these assays. The development of new calcium sensitive dyes and assays has provided sensitive, homogeneous assays which can be readily applied to high throughput screening (HTS). In this paper we describe the full automation of this assay type using a fluorometric imaging plate reader (FLIPR ) integrated into a Beckman/Sagian system to establish a simple robotic system that is well suited for the current medium throughput screening in this area of lead discovery. Using a recently completed HTS we discuss important determinants for FLIPR based screening, highlight some limitations of the current approach, and look at the requirements for future automated systems capable of keeping up with expanding compound files.

Automation↗
PubMed2002

Do children with autism learn to read more readily by computer assisted instruction or traditional book methods? A pilot study.

The study evaluates the progress of eight children aged 3-5 years with autism attending a specialist teaching unit in their development of reading skills in two conditions: computer instructed learning and book based learning. The authors developed a direct observation schedule to monitor autistic behaviours using computerized techniques. The children were matched by age, severity of autistic symptomatology and number of spoken words. They were initially randomly allocated to the computer or book condition and crossed over at 10 weeks. All of the children spent more time on task in the computer condition than in the book condition. By the end of the study after computer assisted learning, five of the eight children could reliably identify at least three words. It was found that children with autism spent more time on reading material when they accessed it through a computer and were less resistant to its use.

Autistic Disorder↗