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Biomedical subjects

Paul Taylor

Publications and source records attributed to Paul Taylor.

At least 19 recordsLinked to original sources
PubMed2006

Inhibitors of Polo-like kinase reveal roles in spindle-pole maintenance.

Polo-like kinases (Plks) have several functions in mitotic progression and are upregulated in many tumor types. Small-molecule Plk inhibitors would be valuable as tools for studying Plk biology and for developing antitumor agents. Guided by homology modeling of the Plk1 kinase domain, we have discovered a chemical series that shows potent and selective Plk1 inhibition. The effects of one such optimized benzthiazole N-oxide, cyclapolin 1 (1), on purified centrosomes indicate that Plks are required to generate MPM2 epitopes, recruit gamma-tubulin and enable nucleation of microtubules. The compound can also promote loss of centrosome integrity and microtubule nucleating ability apparently through increased accessibility of protein phosphatases. We show that treatment of living S2 cells with cyclapolin 1 leads to collapsed spindles, in contrast to the metaphase-arrested bipolar spindles observed after RNAi. This different response to protein depletion and protein inhibition may have significance in the development of antitumor agents.

Animals↗
PubMed2006

Emerging applications for phospho-proteomics in cancer molecular therapeutics.

Protein phosphorylation is a key mechanism of cell regulation in normal and cancer cells. Various new cancer drugs and drug candidates are aimed at protein kinase targets. However, selecting patients likely to respond to these treatments, even among individuals with tumors expressing validated kinase targets remains a major challenge. There exists a need for biomarkers to facilitate the monitoring of modulation of drug-targeted kinase pathways. Phospho-proteomics involves the enrichment of phosphorylated proteins from tissue, and the application of technologies such as mass spectrometry (MS) for the identification and quantification of protein phosphorylation sites. It has potential to provide pharmacodynamic readouts of disease states and cellular drug responses in tumor samples, but technical hurdles and bioinformatics challenges will need to be addressed.

Antineoplastic Agents↗
PubMed2006

Evaluation of PROforma as a language for implementing medical guidelines in a practical context.

BACKGROUND: PROforma is one of several languages that allow clinical guidelines to be expressed in a computer-interpretable manner. How these languages should be compared, and what requirements they should meet, are questions that are being actively addressed by a community of interested researchers. METHODS: We have developed a system to allow hypertensive patients to be monitored and assessed without visiting their GPs (except in the most urgent cases). Blood pressure measurements are performed at the patients' pharmacies and a web-based system, created using PROforma, makes recommendations for continued monitoring, and/or changes in medication. The recommendations and measurements are transmitted electronically to a practitioner with authority to issue and change prescriptions. We evaluated the use of PROforma during the knowledge acquisition, analysis, design and implementation of this system. The analysis focuses on the logical adequacy, heuristic power, notational convenience, and explanation support provided by the PROforma language. RESULTS: PROforma proved adequate as a language for the implementation of the clinical reasoning required by this project. However a lack of notational convenience led us to use UML activity diagrams, rather than PROforma process descriptions, to create the models that were used during the knowledge acquisition and analysis phases of the project. These UML diagrams were translated into PROforma during the implementation of the project. CONCLUSION: The experience accumulated during this study highlighted the importance of structure preserving design, that is to say that the models used in the design and implementation of a knowledge-based system should be structurally similar to those created during knowledge acquisition and analysis. Ideally the same language should be used for all of these models. This means that great importance has to be attached to the notational convenience of these languages, by which we mean the ease with which they can be read, written, and understood by human beings. The importance of notational convenience arises from the fact that a language used during knowledge acquisition and analysis must be intelligible to the potential users of a system, and to the domain experts who provide the knowledge that will be used in its construction.

Antihypertensive Agents↗
PubMed2006

Mechanism of Mos1 transposition: insights from structural analysis.

We present the crystal structure of the catalytic domain of Mos1 transposase, a member of the Tc1/mariner family of transposases. The structure comprises an RNase H-like core, bringing together an aspartic acid triad to form the active site, capped by N- and C-terminal alpha-helices. We have solved structures with either one Mg2+ or two Mn2+ ions in the active site, consistent with a two-metal mechanism for catalysis. The lack of hairpin-stabilizing structural motifs is consistent with the absence of a hairpin intermediate in Mos1 excision. We have built a model for the DNA-binding domain of Mos1 transposase, based on the structure of the bipartite DNA-binding domain of Tc3 transposase. Combining this with the crystal structure of the catalytic domain provides a model for the paired-end complex formed between a dimer of Mos1 transposase and inverted repeat DNA. The implications for the mechanisms of first and second strand cleavage are discussed.

Amino Acid Motifs↗
PubMed2005

Dietary soy isoflavone induced increases in antioxidant and eNOS gene expression lead to improved endothelial function and reduced blood pressure in vivo.

Epidemiological evidence suggests that populations consuming large amounts of soy protein have a reduced incidence of coronary heart disease (1-5). The cardiovascular risks associated with conventional hormone replacement therapy in postmenopausal women (5-7) have precipitated a search for alternative estrogen receptor modulators. Here we report that long-term feeding of rats with a soy protein-rich (SP) diet during gestation and adult life results in decreased oxidative stress, improved endothelial function, and reduced blood pressure in vivo measured by radiotelemetry in aged male offspring. Improved vascular reactivity in animals fed an SP diet was paralleled by increased mitochondrial glutathione and mRNA levels for endothelial nitric oxide synthase (eNOS) and the antioxidant enzymes manganese superoxide dismutase and cytochrome c oxidase. Reduced eNOS and antioxidant gene expression, impaired endothelial function, and elevated blood pressure in animals fed a soy-deficient diet was reversed after refeeding them an SP diet for 6 months. Our findings suggest that an SP diet increases eNOS and antioxidant gene expression in the vasculature and other tissues, resulting in reduced oxidative stress and increased NO bioavailability. The improvement in endothelial function, increased gene expression, and reduced blood pressure by soy isoflavones have implications for alternative therapy for postmenopausal women and patients at risk of coronary heart disease.

Animal Feed↗
PubMed2005

Structural and biochemical studies of human proliferating cell nuclear antigen complexes provide a rationale for cyclin association and inhibitor design.

The interactions between the tumor suppressor protein p21WAF1 and the cyclin-dependent kinase (CDK) complexes and with proliferating cell nuclear antigen (PCNA) regulate and coordinate the processes of cell-cycle progression and DNA replication. We present the x-ray crystal structure of PCNA complexed with a 16-mer peptide related to p21 that binds with a Kd of 100 nM. Two additional crystal structures of native PCNA provide previously undescribed structures of uncomplexed human PCNA and show that significant changes on ligand binding include rigidification of a number of flexible regions on the surface of PCNA. In the competitive binding experiments described here, we show that a 20-mer sequence from p21 can be associated simultaneously with PCNA and CDK/cyclin complexes. A structural model for this quaternary complex is presented in which the C-terminal sequence of p21 acts like double-sided tape and docks to both the PCNA and cyclin molecules. The quaternary complex shows little direct interaction between PCNA and cyclin, giving p21 the role of an adaptor molecule. Taken together, the biochemical and structural results delineate a druggable inhibitor site on the surface of PCNA that may be exploited in the design of peptidomimetics, which will act independently of cyclin-groove inhibitors.

Amino Acid Sequence↗
PubMed2005

emc has a role in dorsal appendage fate formation in Drosophila oogenesis.

extramacrochaetae (emc) functions during many developmental processes in Drosophila, such as sensory organ formation, sex determination, wing vein differentiation, regulation of eye photoreceptor differentiation, cell proliferation and development of the Malpighian tubules, trachea and muscles in the embryo. It encodes a Helix-Loop-Helix transcription factor that negatively regulates bHLH proteins. We show here that emc mRNA and protein are present throughout oogenesis in a dynamic expression pattern and that emc is involved in the regulation of chorionic appendage formation during late oogenesis. Expression of sense and antisense emc constructs as well as emc follicle cell clones leads to eggs with shorter, thicker dorsal appendages that are closer together at base than in the wild type. We demonstrate that emc lies downstream of fs(1)K10, gurken and EGFR in the Grk/EGFR signalling pathway and that it participates in controlling Broad-Complex expression at late stages of oogenesis.

Animals↗
PubMed2005

Association of raised titres of antibodies to Chlamydia pneumoniae with a history of pre-eclampsia.

OBJECTIVE: To establish the prevalence of Chlamydia pneumoniae (C. pneumoniae) infection in a pregnant UK population and to investigate whether C. pneumoniae infection is more common in women with a previous history of pre-eclampsia. DESIGN: Prospective study. SETTING: Academic Hospital. POPULATION: Ninety-one pregnant women (54 parous and 37 nulliparous) at 16-22 weeks of gestation were studied. Of the parous women, 32 had a previous history of pre-eclampsia. METHODS: Peripheral blood was drawn for C. pneumoniae antibodies between 16-22 and 28-40 weeks of gestation. C. pneumoniae antibodies were measured using a solid-phase enzyme immunoassay. According to pregnancy outcome, women were categorised into normal, gestational hypertension and pre-eclampsia groups. MAIN OUTCOME MEASURES: Serum levels of IgG, IgA and IgM C. pneumoniae antibodies. RESULTS: Prevalence of seropositivity to C. pneumoniae was 77%. Parous women had significantly higher levels of IgA and IgM C. pneumoniae antibodies than nulliparous women (P < 0.04). Parous women with previous pre-eclampsia were found to have higher levels of antibodies than parous women with a normal obstetric history (P< or = 0.003). There was no difference in the antibody levels in women with different pregnancy outcomes. CONCLUSIONS: The longitudinal data do not indicate an association between C. pneumoniae infection and pre-eclampsia. However, the subgroup analysis of parous women demonstrated raised C. pneumoniae antibodies in the women with previous pre-eclampsia, and therefore suggests that there may be an association between C. pneumoniae and the disease in this group.

Adult↗
PubMed2005

Single-center experience of encapsulating peritoneal sclerosis in patients on peritoneal dialysis for end-stage renal failure.

BACKGROUND: Encapsulating peritoneal sclerosis (EPS) is a rare but serious complication in patients undergoing continuous ambulatory peritoneal dialysis (CAPD) or automated peritoneal dialysis (APD). It is characterized by a progressive, intra-abdominal, inflammatory process resulting in sheets of fibrous tissue that cover, bind, and constrict the viscera, thereby compromising the motility and function of the bowel. Although recent therapeutic approaches have been reported with variable success, the ability to detect reliably at an early stage patients at risk for EPS would be beneficial and allow treatment standardization. The aim of this study was to evaluate the clinical features of EPS and identify possible risk factors for its development in CAPD and APD patients. METHODS: This was a review of all cases of EPS in a single center over the last 5 years. RESULTS: There were 810 CAPD and APD patients, managed in our program over this period. We identified 27 cases of EPS, giving an overall of 3.3% in this population. The mean duration of CAPD before diagnosis of EPS was 72.6 +/- 39.7 months (range 16-172). Sixteen cases required surgical treatment and were classified as severe; others were treated conservatively (mild to moderate group). Ten patients received tamoxifen treatment with apparent benefit. The overall mortality rate was 29.6%. Eight patients from the severe group and the entire moderate group survived on hemodialysis or transplantation at 48.71 and 27.63 months follow-up, respectively. Peritonitis rates were not different between the 2 groups and peritoneal history was unremarkable compared to overall peritonitis rates in the unit. Data on small solute transport were not available in all patients in this retrospective analysis. CONCLUSION: EPS is a serious, life-threatening complication of CAPD. Most cases had PD duration of more than 4 years. Careful monitoring by CT scans of the peritoneal membrane in patients beyond 5 years, and early catheter removal in patients with peritoneal thickening should be considered for long-term CAPD patients. Treatment with tamoxifen may be of benefit in these patients.

Adult↗
PubMed2005

Computer-aided detection in the United Kingdom National Breast Screening Programme: prospective study.

PURPOSE: To evaluate prospectively the recall and cancer detection rates with and without computer-aided detection (CAD) in the United Kingdom National Health Service Breast Screening Programme. MATERIALS AND METHODS: The study had appropriate ethics committee approval. Informed consent was not required; however, patients were informed that their mammograms might be used in research efforts, and all patients agreed to participate. Mammograms obtained in 6111 women (mean age, 58.4 years) undergoing routine screening every 3 years were analyzed with a CAD system. Mammograms were independently double read. Twelve readers participated. Readers recorded an initial evaluation, viewed the CAD prompts, and recorded a final evaluation. Recall to assessment was decided after arbitration. Sensitivities were calculated for single reading, single reading with CAD, and double reading, as a proportion of the total number of cancers detected by using double reading with CAD. RESULTS: A total of 62 cancers were detected in 61 women. CAD prompted 51 (84%) of 61 radiographically detected cancers. Of 12 cancers missed on single reading, nine were correctly prompted; however, seven prompts were overruled by the reader. Sensitivity of single reading was 90.2% (95% confidence interval [CI]: 83.0%, 95.0%), single reading with CAD was 91.5% (95% CI: 85.0%, 96.0%), and double reading without CAD was 98.4% (95% CI: 91.0%, 100%). Cancer detection rate was 1%. Recall to assessment rate was 6.1%, with an increase of 5.8% because of CAD. Average time required, per reader, to read a case was 25 seconds without CAD and 45 seconds with CAD. CONCLUSION: CAD increases sensitivity of single reading by 1.3%, whereas double reading increases sensitivity by 8.2%.

Adult↗
PubMed2005

Evaluating telemedicine systems and services.

The evaluation of telemedicine involves attempts to answer a wide range of questions involved in making decisions about safety, about practicality and about utility. Roughly speaking, if we wish to provide a telemedicine service we should first establish that it is safe, next that it is practical and finally that it is worthwhile. In establishing safety, most laboratory studies of telemedicine have a common structure, and consist of the following steps: (1) selection of cases; (2) interpretation; (3) comparison with a gold standard; (4) statistical analyses. Most of the studies to establish the practicality of telemedicine have been carried out as demonstrations, to show that a proposed application can be implemented in a chosen setting. In terms of utility, telemedicine has been used to improve the efficiency of an existing service or to make an existing service available to a new community. One of the difficulties is that the vendors of relatively expensive telemedicine systems and services disseminate much of the information on the topic. We have to focus not on the glamorous technology but on the underlying issue of how the participants in health care (patients, general practitioners, specialists) can communicate more effectively, using the range of technological options open to them. Ensuring that the most appropriate technology is used in the most effective way should be the primary aim of telemedicine research. There is now sufficient evidence for us to be confident that telemedicine is a safe alternative to conventional care in a variety of situations and for a number of clinical conditions. Reliable evidence that it is a practical and cost-effective alternative is, at the time of writing, harder to find.

Delivery of Health Care↗
PubMed2005

A pilot clinical study of continuous intravenous ascorbate in terminal cancer patients.

Case studies suggest that vitamin C, given intravenously at doses of 10-100 grams/day can improve patient well being and in some cases, reduce tumor size. While ascorbate is generally considered safe, clinical data on high intravenous doses is limited. Twenty-four late stage terminal cancer patients were given continuous infusions of 150 to 710 mg/kg/day for up to eight weeks. Blood chemistry and blood count profiles were obtained at roughly one-week intervals while patient health, adverse events and tumor progression were monitored. The majority of patients were vitamin C deficient prior to treatment. Intravenous infusions increased plasma ascorbate concentrations to a mean of 1.1 mM. The most common adverse events reported were nausea, edema, and dry mouth or skin; and these were generally minor. Two Grade 3 adverse events 'possibly related' to the agent were reported: one patient with a history of renal calculi developed a kidney stone after thirteen days of treatment and another patient experienced hypokalemia after six weeks of treatment. White blood cell counts were stable while hemoglobin and hematocrit levels dropped slightly during treatment, consistent with trends observed prior to therapy. Blood creatinine, BUN, glucose, and uric acid concentrations decreased or remained stable during therapy, suggesting that ascorbate infusions did not adversely affect renal function. One patient had stable disease and continued the treatment for forty-eight weeks. These data suggest that intravenous vitamin C therapy for cancer is relatively safe, provided the patient does not have a history of kidney stone formation.

Ascorbic Acid↗
PubMed2004

Use of a computerized guideline for glucose regulation in the intensive care unit improved both guideline adherence and glucose regulation.

OBJECTIVE: To measure the impact of a computerized guideline for glucose regulation in an ICU. DESIGN: A randomized, controlled trial with an off-on-off design. METHODS: We implemented a glucose regulation guideline in an intensive care unit in paper form during the first study period. During the second period, the guideline was randomly applied in either paper or computerized form. In the third period, the guideline was available only in paper form. MEASUREMENTS AND RESULTS: We analyzed data for 484 patients. During the intervention period, the control group included 54 patients and the computerized intervention group included 66 patients. The two guideline-related outcome measures consisted of compliance with: (a) glucose measurement timing recommendations and (b) insulin dose advice. We measured clinical impact as the proportion of time that glucose levels fell within target range. In the first (paper-based) study period, 29.0% of samples occurred with optimal timing; during the second period, this increased to 35.5% for paper-based and to 40.2% for computerized protocols. The third study period timeliness scores reverted to the first period rates. Late (suboptimal) sampling occurred for 66% of glucose measurements in the first study period, for 42% of paper-based and 28% of computer-based protocol samples in the second period, and for 50.0% of samples in the third study period. In the first study period, insulin-dosing guideline compliance was 56.3%; in the second period, it was 64.2% for paper-based and 77.3% for computer-based protocols, and it fell to 42.4% in the third period. For the second study period, the time that a patient's glucose values fell within target range improved for both the control (52.9%) and the computerized groups (54.2%) compared with the first study period (44.3%) and the third period (42.3%). CONCLUSION: Implementing a computerized version of a guideline significantly improved timeliness of measurements and glucose level regulation for critically ill patients compared with implementing a paper-based version of the guideline.

Blood Glucose↗
PubMed2004

Octaheme tetrathionate reductase is a respiratory enzyme with novel heme ligation.

We have isolated a soluble cytochrome from Shewanella oneidensis that contains eight covalently attached heme groups and determined its crystal structure. One of these hemes exhibits novel ligation of the iron atom by the epsilon-amino group of a lysine residue, despite its attachment via a typical CXXCH motif. This heme is most likely the active site for tetrathionate reduction, a reaction catalyzed efficiently by this enzyme.

Binding Sites↗
PubMed2004

Proteomic, functional, and domain-based analysis of in vivo 14-3-3 binding proteins involved in cytoskeletal regulation and cellular organization.

BACKGROUND: 14-3-3 proteins are abundant and conserved polypeptides that mediate the cellular effects of basophilic protein kinases through their ability to bind specific peptide motifs phosphorylated on serine or threonine. RESULTS: We have used mass spectrometry to analyze proteins that associate with 14-3-3 isoforms in HEK293 cells. This identified 170 unique 14-3-3-associated proteins, which show only modest overlap with previous 14-3-3 binding partners isolated by affinity chromatography. To explore this large set of proteins, we developed a domain-based hierarchical clustering technique that distinguishes structurally and functionally related subsets of 14-3-3 target proteins. This analysis revealed a large group of 14-3-3 binding partners that regulate cytoskeletal architecture. Inhibition of 14-3-3 phosphoprotein recognition in vivo indicates the general importance of such interactions in cellular morphology and membrane dynamics. Using tandem proteomic and biochemical approaches, we identify a phospho-dependent 14-3-3 binding site on the A kinase anchoring protein (AKAP)-Lbc, a guanine nucleotide exchange factor (GEF) for the Rho GTPase. 14-3-3 binding to AKAP-Lbc, induced by PKA, suppresses Rho activation in vivo. CONCLUSION: 14-3-3 proteins can potentially engage around 0.6% of the human proteome. Domain-based clustering has identified specific subsets of 14-3-3 targets, including numerous proteins involved in the dynamic control of cell architecture. This notion has been validated by the broad inhibition of 14-3-3 phosphorylation-dependent binding in vivo and by the specific analysis of AKAP-Lbc, a RhoGEF that is controlled by its interaction with 14-3-3.

14-3-3 Proteins↗
PubMed2004

Predictive adaptive responses to maternal high-fat diet prevent endothelial dysfunction but not hypertension in adult rat offspring.

BACKGROUND: Population-based studies suggest that fetal adaptive responses to maternal dietary imbalance confer survival benefit when the postnatal diet remains suboptimal but increase susceptibility to cardiovascular disease when postnatal nutrition is improved. We have investigated "predictive adaptive" responses in a rodent model in which adult offspring of fat-fed dams develop characteristics of the metabolic syndrome. METHODS AND RESULTS: Sprague-Dawley rats were fed a fat-rich diet or normal chow throughout pregnancy and weaning. Vascular endothelial function and blood pressure were determined in 180-day-old offspring of fat-fed dams raised on standard chow (FC) or on the fat-rich diet (FF) and in offspring of chow-fed dams raised on chow (CON). Small mesenteric artery endothelium-dependent dilation to acetylcholine was impaired in male and female FC (by ANOVA, P<0.001 versus CON) but similar to CON in FF (P=NS). Blood glucose was lower in FF versus FC. Heart rate was reduced in male FC versus CON (P<0.05) but not in FF. Plasma triglyceride concentrations were reduced in male FF compared with CON (P<0.05). Blood pressure was raised in female FC (systolic, 132.5+/-3.0 mm Hg versus CON, 119.0+/-3.8 mm Hg, P<0.05; diastolic, 91.2+/-1.7 mm Hg versus CON, 81.1+/-1.4 mm Hg, P<0.05) and in female FF (systolic, 132.5+/-4.2 mm Hg versus CON, P<0.05; diastolic, 91.0+/-1.9 mm Hg versus CON, P<0.05). Blood pressure was similar to CON in male FC and FF. CONCLUSIONS: Predictive adaptive responses prevent endothelial dysfunction and reduced heart rate in offspring of fat-fed dams if offspring are raised on the same diet but do not prevent development of raised blood pressure.

Adaptation, Physiological↗
PubMed2004

Expression, purification and preliminary crystallographic studies of a single-point mutant of Mos1 mariner transposase.

A soluble single-point mutant of full-length Mos1 mariner transposase (MW = 40.7 kDa) has been overexpressed in Escherichia coli, purified to 95% homogeneity and crystallized. This provides the first example of the crystallization of a eukaryotic transposase. The native crystals diffract to 2.5 A resolution and show tetragonal symmetry, with unit-cell parameters a = b = 44.5, c = 205.6 A. Multiple-wavelength anomalous data from a selenomethionyl form of the protein and data from a heavy-atom derivative have been collected.

Amino Acid Sequence↗