PubMed Health⌕ Search

Biomedical subjects

Paul Davis

Publications and source records attributed to Paul Davis.

At least 19 recordsLinked to original sources
PubMed2006

Mast cells dysregulate apoptotic and cell cycle genes in mucosal squamous cell carcinoma.

BACKGROUND: Mucosal squamous cell carcinoma of the head and neck is a disease of high mortality and morbidity. Interactions between the squamous cell carcinoma and the host's local immunity, and how the latter contributes to the biological behavior of the tumor are unclear. In vivo studies have demonstrated sequential mast cell infiltration and degranulation during squamous cell carcinogenesis. The degree of mast cell activation correlates closely with distinct phases of hyperkeratosis, dysplasia, carcinoma in-situ and invasive carcinoma. However, the role of mast cells in carcinogenesis is unclear. AIM: This study explores the effects of mast cells on the proliferation and gene expression profile of mucosal squamous cell carcinoma using human mast cell line (HMC-1) and human glossal squamous cell carcinoma cell line (SCC25). METHODS: HMC-1 and SCC25 were co-cultured in a two-compartment chamber, separated by a polycarbonate membrane. HMC-1 was stimulated to degranulate with calcium ionophore A23187. The experiments were done in quadruplicate. Negative controls were established where SCC25 were cultured alone without HMC-1. At 12, 24, 48 and 72 hours, proliferation and viability of SCC25 were assessed with MTT colorimetric assay. cDNA microarray was employed to study differential gene expression between co-cultured and control SCC25. RESULTS: HMC-1/SCC25 co-culture resulted in suppression of growth rate for SCC-25 (34% compared with 110% for the control by 72 hours, p < 0.001), and dysregulation of genes TRAIL, BIRC4, CDK6, Cyclin G2 and CDC6 in SCC25. CONCLUSION: We show that mast cells have a direct inhibitory effect on the proliferation of mucosal squamous cell carcinoma in vitro by dysregulating key genes in apoptosis and cell cycle control.

Journal Article↗
PubMed2006

WormBase: new content and better access.

WormBase (http://wormbase.org), a model organism database for Caenorhabditis elegans and other related nematodes, continues to evolve and expand. Over the past year WormBase has added new data on C.elegans, including data on classical genetics, cell biology and functional genomics; expanded the annotation of closely related nematodes with a new genome browser for Caenorhabditis remanei; and deployed new hardware for stronger performance. Several existing datasets including phenotype descriptions and RNAi experiments have seen a large increase in new content. New datasets such as the C.remanei draft assembly and annotations, the Vancouver Fosmid library and TEC-RED 5' end sites are now available as well. Access to and searching WormBase has become more dependable and flexible via multiple mirror sites and indexing through Google.

Animals↗
PubMed2006

Improving management of musculoskeletal disorders in primary care: the Joint Adventures Program.

Musculoskeletal disorders represent a large and growing clinical challenge to primary care clinicians. Unfortunately, there appears to be a gap in current training and continuing education to meet this challenge. We used script concordance within a continuing medical education program entitled "Joint Adventures" to assist family physicians to acquire the knowledge, skills, and tools they need to improve their management of musculoskeletal disorders. Program workshops were coordinated through a national continuing education program of the College of Family Physicians of Canada. A group of 54 experts in musculoskeletal disorders including family physicians, rheumatologists, and orthopedists developed cases for six areas of management that were identified by family physicians during a needs survey delivered at a national scientific congress in primary care. Script concordance methodology was used in the Joint Adventures workshop to address knowledge gaps or lack of group consensus in the six areas including (1) diagnosis of osteoarthritis, (2) treatment and management of osteoarthritis, (3) treatment and management of rheumatoid arthritis, (4) diagnosis and treatment of back pain, (5) diagnosis and treatment of fibromyalgia and diagnosis, and (6) treatment of shoulder pain. Each workshop session included 5-30 family physicians, a specialist expert, and a family physician facilitator. Before each session, a group needs assessment was conducted to identify which one or two of the six cases would be used. Perceived knowledge and skill acquisition, self-assessed change in practice, and satisfaction with the program were measured at the conclusion of each session and again at 3 months post program. All programs were delivered from March 2003 to September 2005. Six hundred and fifty family physicians from across Canada completed the program. In general, participants reached concordance with each case. Measures of knowledge and skill acquisition and self-assessed change in practice were significantly improved with high rates of program satisfaction. The Joint Adventures program provided family physicians with knowledge and skills that changed their care of musculoskeletal disorders. This was achieved using consensus that was sensitive to local needs. Further use should be evaluated in other areas of medical practice as well.

Canada↗
PubMed2006

The impact of sex and exercise duration on growth hormone secretion.

Previous research clearly indicates a linear relationship between exercise intensity and growth hormone (GH) release and that this relationship is influenced by sex. The present study examined the GH response to increasing exercise duration in young men and women. Fifteen healthy subjects (8 men and 7 women) completed three randomly assigned exercise sessions (30, 60, and 120 min) at 70% of peak oxygen consumption. Blood samples were collected every 10 min beginning 30 min before exercise, for a total of 240 min. Total integrated GH concentration (IGHC) increased with increasing exercise duration for men and women (601, 1,394, and 2,360 microg/l.4 h; 659, 1,009 and 1,243 microg/l.4 h for 30, 60, and 120 min of exercise, respectively). Regression analysis revealed that IGHC (logarithmically transformed) was significantly influenced by exercise duration (logarithmically transformed) (120 min > 60 min > 30 min) and that a significant sex-dependent effect was present even after adjustments for fitness level and percent body fat (men > women). The slope of the regression line was greater for men than for women (1.003 vs. 0.612; P = 0.013), but the average height of the regression line was greater for women (7.287 vs. 6.595; P < 0.001). Although GH secretory pulse half-duration was greater in women (P = 0.001), and GH half-life was greater in men (P = 0.001), they were not affected by exercise duration. The total mass of GH secreted during exercise increased with exercise duration (P < 0.001) but was not affected by sex (P = 0.137). Results from the present investigation indicate that when exercise intensity is constant, exercise duration significantly increases IGHC and that this relationship is sex dependent.

Adult↗
PubMed2006

The multidrug-resistant human pathogen Clostridium difficile has a highly mobile, mosaic genome.

We determined the complete genome sequence of Clostridium difficile strain 630, a virulent and multidrug-resistant strain. Our analysis indicates that a large proportion (11%) of the genome consists of mobile genetic elements, mainly in the form of conjugative transposons. These mobile elements are putatively responsible for the acquisition by C. difficile of an extensive array of genes involved in antimicrobial resistance, virulence, host interaction and the production of surface structures. The metabolic capabilities encoded in the genome show multiple adaptations for survival and growth within the gut environment. The extreme genome variability was confirmed by whole-genome microarray analysis; it may reflect the organism's niche in the gut and should provide information on the evolution of virulence in this organism.

Adaptation, Physiological↗
PubMed2006

The genome of Rhizobium leguminosarum has recognizable core and accessory components.

BACKGROUND: Rhizobium leguminosarum is an alpha-proteobacterial N2-fixing symbiont of legumes that has been the subject of more than a thousand publications. Genes for the symbiotic interaction with plants are well studied, but the adaptations that allow survival and growth in the soil environment are poorly understood. We have sequenced the genome of R. leguminosarum biovar viciae strain 3841. RESULTS: The 7.75 Mb genome comprises a circular chromosome and six circular plasmids, with 61% G+C overall. All three rRNA operons and 52 tRNA genes are on the chromosome; essential protein-encoding genes are largely chromosomal, but most functional classes occur on plasmids as well. Of the 7,263 protein-encoding genes, 2,056 had orthologs in each of three related genomes (Agrobacterium tumefaciens, Sinorhizobium meliloti, and Mesorhizobium loti), and these genes were over-represented in the chromosome and had above average G+C. Most supported the rRNA-based phylogeny, confirming A. tumefaciens to be the closest among these relatives, but 347 genes were incompatible with this phylogeny; these were scattered throughout the genome but were over-represented on the plasmids. An unexpectedly large number of genes were shared by all three rhizobia but were missing from A. tumefaciens. CONCLUSION: Overall, the genome can be considered to have two main components: a 'core', which is higher in G+C, is mostly chromosomal, is shared with related organisms, and has a consistent phylogeny; and an 'accessory' component, which is sporadic in distribution, lower in G+C, and located on the plasmids and chromosomal islands. The accessory genome has a different nucleotide composition from the core despite a long history of coexistence.

ATP-Binding Cassette Transporters↗
PubMed2006

WormBase: better software, richer content.

WormBase (http://wormbase.org), the public database for genomics and biology of Caenorhabditis elegans, has been restructured for stronger performance and expanded for richer biological content. Performance was improved by accelerating the loading of central data pages such as the omnibus Gene page, by rationalizing internal data structures and software for greater portability, and by making the Genome Browser highly customizable in how it views and exports genomic subsequences. Arbitrarily complex, user-specified queries are now possible through Textpresso (for all available literature) and through WormMart (for most genomic data). Biological content was enriched by reconciling all available cDNA and expressed sequence tag data with gene predictions, clarifying single nucleotide polymorphism and RNAi sites, and summarizing known functions for most genes studied in this organism.

Animals↗
PubMed2006

Walnuts reduce aortic ET-1 mRNA levels in hamsters fed a high-fat, atherogenic diet.

Walnut consumption is associated with reduced coronary vascular disease (CVD) risk; however, the mechanisms responsible remain incompletely understood. Recent clinical studies suggested that these mechanisms involve non-plasma lipid-related effects on endothelial function. Male Golden Syrian hamsters (12 groups, n=10-15) were fed for 26 wk atherosclerotic, high-fat, hyperlipidemic diets with increasing concentrations of whole walnuts (61-150 g/kg diet), or alpha-tocopherol (alpha-T, 8.1-81 mg/kg diet) and single diets with either walnut oil (32 g/kg diet) or pure gamma-tocopherol (gamma-T; 81 mg/kg diet) added. Aortic endothelin 1 (ET-1), an important endothelial regulator, was assayed as mRNA. Aortic cholesterol ester (CE) concentration along with other vascular stress markers (Cu/Zn and Mn superoxide dismutase, biliverdin reductase) and plasma lipid concentrations were determined. Hyperlipidemia (plasma LDL cholesterol approximately 6 times normal) occurred in all groups. Aortic CE concentration, a measure of atherosclerotic plaque, was highest in the lowest alpha-T only group and declined significantly with increasing alpha-T. The aortic CE of all walnut groups was decreased significantly relative to the lowest alpha-T only group but showed no dose response. The diets did not produce changes in the other vascular stress markers, whereas aortic ET-1 mRNA levels declined dramatically with increasing dietary walnuts (to a 75% reduction in the highest walnut content group compared with the lowest alpha-T group) but were unaltered in the alpha-T groups or gamma-T group. The study results are consistent with those of human walnut feeding studies and suggest that the mechanisms underlying those results are mediated in part by ET-1-dependent mechanisms. The contrasting results between the alpha-tocopherol or gamma-tocopherol diets and the walnut diets also make it unlikely that the non-plasma lipid-related CVD effects of walnuts are due to their alpha-tocopherol or gamma-tocopherol content. Finally, the results indicate that the walnut fat compartment is a likely location for the components responsible for the reduced aortic CE concentration.

Animal Feed↗
PubMed2006

Enhanced recognition of facial expressions of disgust in opiate users receiving maintenance treatment.

AIMS: Accurate recognition of facial expressions of emotion is critical in interpersonal interaction but is impaired in alcoholics, even after a period of abstinence. Little is known of whether other drug-dependent populations also show these impairments. This study aimed to investigate facial expression recognition by chronic opiate users. DESIGN: An independent group design was used to compare 20 participants receiving opiate substitution treatment, 20 ex-opiate users in rehabilitation (average abstinence of 6 months) and 21 unemployed healthy controls. MEASUREMENTS: The accuracy and speed of recognizing morphed emotional facial expressions were assessed using an emotional hexagon task. FINDINGS: Current opiate users were significantly more accurate than ex-users at recognizing expressions of disgust. They were also generally slower than controls in recognizing all expressions, and slower than ex-opiate users in recognizing surprise, happy and fearful expressions. CONCLUSIONS: Opiate users in maintenance treatment show a heightened ability to recognize facial expressions of disgust. We suggest that this may reflect increased exposure to other people's expressions of disgust and/or priming by the physical and social environments encountered by opiate-dependent individuals. Further, opiate maintained individuals' global slowness in processing emotional expressions may reflect the sedative effects of methadone.

Adult↗
PubMed2005

An evidence-based approach to prescribing nonsteroidal antiinflammatory drugs. Third Canadian Consensus Conference.

OBJECTIVE: To revisit our previous evidence-based recommendations on the appropriate prescription of nonsteroidal antiinflammatory drugs (NSAID) with particular emphasis on cyclooxygenase-2 selective inhibitors (coxibs). METHODS: Needs assessments were conducted among Canadian physicians to determine their educational needs surrounding NSAID/coxibs. A survey of patients with arthritis was also conducted. Consensus participants reviewed articles relating to NSAID/coxibs in peer-reviewed journals between January 2000 and December 2004. At the consensus meeting, held January 21-23, 2005, participants discussed selected topics, after which recommendations were formulated and debated. Results. At the time of the meeting, it was agreed that emerging cardiovascular data were not clear enough to decide whether unanticipated cardiovascular events associated with coxibs represent a class effect or an effect of an individual drug. However, publications that appeared shortly after the meeting, as well as data presented at both the Joint Meeting of the Arthritis Advisory Committee and the Drug Safety and Risk Management Advisory Committee of the US Food and Drug Administration, February 16-18, 2005, and Health Canada's Expert Advisory Panel on the Safety of Cox-2 Selective NSAID, June 9-10, 2005, clarified that all available coxibs do carry some degree of cardiovascular risk, denoting a class effect. Our consensus group made the following specific recommendations: (1) Patients should be fully informed about treatment options, including the need to balance between cardiovascular risks and gastrointestinal (GI) benefits of NSAID/coxibs. (2) Coxibs are as effective as nonselective NSAID and superior to acetaminophen for the symptoms of arthritis. Topical NSAID may also be beneficial. (3) Coxibs are associated with fewer severe GI complications than nonselective NSAID. A proton pump inhibitor (PPI) should be prescribed if an NSAID must be used in a patient at increased GI risk. (4) The renal/blood pressure (BP) impact of coxibs is similar to that of NSAID. (5) In individuals at risk, creatinine clearance and BP should be determined at baseline and shortly after treatment begins. (6) In the geriatric population, use of nonpharmacological therapies should be maximized, and special caution is required before prescribing oral NSAID/coxibs. (7) Patients taking rofecoxib have been shown to have an increased risk of cardiovascular events. Current data suggest that this increased cardiovascular risk may be an effect of the NSAID/coxib class. (8) Although the data are limited, coxibs may be more cost-effective for patients at high GI risk than nonselective NSAID plus proprietary PPI. CONCLUSION: Coxibs continue to be an option in the treatment armamentarium. Given the evolving cardiovascular information, physicians and patients should weigh the benefits and risks of NSAID/coxib treatment. This concern emphasizes the need to routinely reassess patients' risks. These recommendations, which were formulated according to the Appraisal of Guidelines for Research and Evaluation, are intended to be used as guidelines to supplement, but not replace, the physician's judgment in clinical decision-making.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2005

Patients' awareness, utilization, and satisfaction with treatment modalities for the management of their osteoarthritis.

The objective of this study was to evaluate the knowledge, awareness, utilization, and satisfaction of patients with different treatment modalities for osteoarthritis (OA). Patients with a diagnosis of OA of the knee or hip who had attended a rheumatology referral clinic over the preceding 2 years were eligible. A six-page self-administered questionnaire was mailed to them. Responses were anonymous. One hundred and six completed questionnaires were returned. The average age of the respondents was 64 years and included 71 females. Ninety-four percent of respondents had at least 8 years of formal education, and 75% had had OA for at least 5 years. Seventy-five percent successfully defined OA. The majority had heard of most treatment modalities. Seventy-one percent had tried cyclooxygenase-2 inhibitors (COXIBs), 79% analgesics, and 56% physiotherapy. Twenty-six percent had had surgery for their OA. Of those that had tried the various treatment options, the most satisfaction occurred with surgery, pool therapy, walking aids, and narcotic analgesics. Fifty-five percent found traditional nonsteroidal anti-inflammatory drugs (NSAIDs) helpful and 65% benefited from the COXIBs. Treatment reported as providing the most improvement in function was surgery, followed by steroid injections, COXIB therapy, and traditional NSAIDs. Treatment modalities providing the most symptomatic improvement were surgery, followed by COXIBs and steroid injections. When treatment options were compared, their rank ordering differed when considering overall satisfaction, functional improvement, and symptomatic relief. The participants in this study were well informed as to the nature of their disease and its treatment. A wide number of therapies had been tried, most of which were well tolerated. According to patient perception, those undergoing surgical treatment had the best improvement in symptoms and function. For those using anti-inflammatories (NSAIDs or COXIBs) improvement occurred in >50%, though this was less than for physiotherapy and analgesics. Based on this cohort of patients, treatments that were rated highly (such as surgery) were not necessarily those that were the most widely experienced. Conversely, those therapies that were the most widely accessed (such as analgesics) were not necessarily those that provided the maximum perceived benefit. We conclude that in the continued absence of specific disease-modifying therapies for OA, multiple therapeutic options need to be explored to address individual patient's functional and symptomatic needs.

Analgesics↗
PubMed2005

Crystal structure of the mosquito-larvicidal toxin Cry4Ba and its biological implications.

Cry4Ba, isolated from Bacillus thuringiensis subsp. israelensis, is specifically toxic to the larvae of Aedes and Anopheles mosquitoes. The structure of activated Cry4Ba toxin has been determined by multiple isomorphous replacement with anomalous scattering and refined to R(cryst) = 20.5% and R(free)= 21.8% at 1.75 Angstroms resolution. It resembles previously reported Cry toxin structures but shows the following distinctions. In domain I the helix bundle contains only the long and amphipathic helices alpha3-alpha7. The N-terminal helices alpha1-alpha2b, absent due to proteolysis during crystallisation, appear inessential to toxicity. In domain II the beta-sheet prism presents short apical loops without the beta-ribbon extension of inner strands, thus placing the receptor combining sites close to the sheets. In domain III the beta-sandwich contains a helical extension from the C-terminal strand beta23, which interacts with a beta-hairpin excursion from the edge of the outer sheet. The structure provides a rational explanation of recent mutagenesis and biophysical data on this toxin. Furthermore, added to earlier structures from the Cry toxin family, Cry4Ba completes a minimal structural database covering the Coleoptera, Lepidoptera, Diptera and Lepidoptera/Diptera specificity classes. A multiple structure alignment found that the Diptera-specific Cry4Ba is structurally more closely similar to the Lepidoptera-specific Cry1Aa than the Coleoptera-specific Cry3Aa, but most distantly related to Lepidoptera/Diptera-specific Cry2Aa. The structures are most divergent in domain II, supporting the suggestion that this domain has a major role in specificity determination. They are most similar in the alpha3-alpha7 major fragment of domain I, which contains the alpha4-alpha5 hairpin crucial to pore formation. The collective knowledge of Cry toxin structure and mutagenesis data will lead to a more critical understanding of the structural basis for receptor binding and pore formation, as well as allowing the scope of diversity to be better appreciated.

Amino Acid Sequence↗
PubMed2005

WormBase: a comprehensive data resource for Caenorhabditis biology and genomics.

WormBase (http://www.wormbase.org), the model organism database for information about Caenorhabditis elegans and related nematodes, continues to expand in breadth and depth. Over the past year, WormBase has added multiple large-scale datasets including SAGE, interactome, 3D protein structure datasets and NCBI KOGs. To accommodate this growth, the International WormBase Consortium has improved the user interface by adding new features to aid in navigation, visualization of large-scale datasets, advanced searching and data mining. Internally, we have restructured the database models to rationalize the representation of genes and to prepare the system to accept the genome sequences of three additional Caenorhabditis species over the coming year.

Animals↗
PubMed2005

Videoconferences for rural physicians' continuing health education.

The University of Alberta uses videoconferencing to link physicians in interactive continuing health education. We examined evaluations of 29 videoconferences for rural practitioners during the programme year September 2003-May 2004. The evaluation form, completed by participants following the presentation, used both quantitative and qualitative methods of data collection. The average attendance for the videoconference sessions was 40 people. A total of 593 evaluations were collected (response rate 51%). The audience were very satisfied with the programme and felt that the sessions were relevant to their practice. The interactive discussion component was rated very highly. Most respondents stated that they would change their practice based on the information discussed. It is clear from our survey that videoconferencing is useful in overcoming the barriers of distance and that small physician numbers create a positive environment for adult learning.

Adult↗
PubMed2004

A proposal of criteria for the classification of systemic sclerosis.

BACKGROUND: Sensitive and specific criteria for the classification of systemic sclerosis are required by clinicians and investigators to achieve higher quality clinical studies and approaches to therapy. A clinical study of systemic sclerosis patients in Europe and Canada led to a set of criteria that achieve high sensitivity and specificity. MATERIAL/METHODS: Both clinical and laboratory investigations of patients with systemic sclerosis, related conditions and diseases with clinical features that can be mistaken as part of the systemic sclerosis spectrum were undertaken. Laboratory investigations included the detection of autoantibodies to centromere proteins, Scl-70 (topoisomerase I), and fibrillarin (U3-RNP). RESULTS: Based on the investigation of 269 systemic sclerosis patients and 720 patients presenting with related and confounding conditions, the following set of criteria for the classification of systemic sclerosis was proposed: 1) autoantibodies to: centromere proteins, Scl-70 (topo I), fibrillarin; 2) bibasilar pulmonary fibrosis; 3) contractures of the digital joints or prayer sign; 4) dermal thickening proximal to the wrists; 5) calcinosis cutis; 6) Raynaud's phenomenon; 7) esophageal distal hypomotility or reflux-esophagitis; 8) sclerodactyly or non-pitting digital edema; 9) teleangiectasias. The classification of definite SSc requires at least three of the above criteria. CONCLUSIONS: Criteria for the classification of systemic sclerosis have been proposed. Preliminary testing has defined the sensitivity and specificity of these criteria as high as 99% and 100%, respectively. Testing and validation of the proposed criteria by other clinical centers is required.

Diagnosis, Differential↗
PubMed2004

Genomic plasticity of the causative agent of melioidosis, Burkholderia pseudomallei.

Burkholderia pseudomallei is a recognized biothreat agent and the causative agent of melioidosis. This Gram-negative bacterium exists as a soil saprophyte in melioidosis-endemic areas of the world and accounts for 20% of community-acquired septicaemias in northeastern Thailand where half of those affected die. Here we report the complete genome of B. pseudomallei, which is composed of two chromosomes of 4.07 megabase pairs and 3.17 megabase pairs, showing significant functional partitioning of genes between them. The large chromosome encodes many of the core functions associated with central metabolism and cell growth, whereas the small chromosome carries more accessory functions associated with adaptation and survival in different niches. Genomic comparisons with closely and more distantly related bacteria revealed a greater level of gene order conservation and a greater number of orthologous genes on the large chromosome, suggesting that the two replicons have distinct evolutionary origins. A striking feature of the genome was the presence of 16 genomic islands (GIs) that together made up 6.1% of the genome. Further analysis revealed these islands to be variably present in a collection of invasive and soil isolates but entirely absent from the clonally related organism B. mallei. We propose that variable horizontal gene acquisition by B. pseudomallei is an important feature of recent genetic evolution and that this has resulted in a genetically diverse pathogenic species.

Adult↗
PubMed2004

WormBase: a multi-species resource for nematode biology and genomics.

WormBase (http://www.wormbase.org/) is the central data repository for information about Caenorhabditis elegans and related nematodes. As a model organism database, WormBase extends beyond the genomic sequence, integrating experimental results with extensively annotated views of the genome. The WormBase Consortium continues to expand the biological scope and utility of WormBase with the inclusion of large-scale genomic analyses, through active data and literature curation, through new analysis and visualization tools, and through refinement of the user interface. Over the past year, the nearly complete genomic sequence and comparative analyses of the closely related species Caenorhabditis briggsae have been integrated into WormBase, including gene predictions, ortholog assignments and a new synteny viewer to display the relationships between the two species. Extensive site-wide refinement of the user interface now provides quick access to the most frequently accessed resources and a consistent browsing experience across the site. Unified single-page views now provide complete summaries of commonly accessed entries like genes. These advances continue to increase the utility of WormBase for C.elegans researchers, as well as for those researchers exploring problems in functional and comparative genomics in the context of a powerful genetic system.

Animals↗