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1.
J Clin Virol ; 104: 1-4, 2018 07.
Article in English | MEDLINE | ID: mdl-29702350

ABSTRACT

BACKGROUND: Norovirus is the leading cause of epidemic and sporadic acute gastroenteritis (AGE) in the United States. Widespread prevalence necessitates implementation of accurate norovirus detection assays in clinical diagnostic laboratories. OBJECTIVE: To evaluate RIDA®GENE norovirus GI/GII real-time RT-PCR assay (RGN RT-PCR) using stool samples from patients with sporadic AGE. STUDY DESIGN: Patients between 14 days to 101 years of age with symptoms of AGE were enrolled prospectively at four sites across the United States during 2014-2015. Stool specimens were screened for the presence of norovirus RNA by the RGN RT-PCR assay. Results were compared with a reference method that included conventional RT-PCR and sequencing of a partial region of the 5'end of the norovirus ORF2 gene. RESULTS: A total of 259 (36.0%) of 719 specimens tested positive for norovirus by the reference method. The RGN RT-PCR assay detected norovirus in 244 (94%) of these 259 norovirus positive specimens. The sensitivity and specificity (95% confidence interval) of the RGN RT-PCR assay for detecting norovirus genogroup (G) I was 82.8% (63.5-93.5) and 99.1% (98.0-99.6) and for GII was 94.8% (90.8-97.2) and 98.6% (96.9-99.4), respectively. Seven specimens tested positive by the RGN-RT PCR that were negative by the reference method. The fifteen false negative samples were typed as GII.4 Sydney, GII.13, GI.3, GI.5, GI.2, GII.1, and GII.3 in the reference method. CONCLUSIONS: The RGN RT-PCR assay had a high sensitivity and specificity for the detection of norovirus in stool specimens from patients with sporadic AGE.


Subject(s)
Caliciviridae Infections/diagnosis , Feces/virology , Gastroenteritis/diagnosis , Molecular Diagnostic Techniques/methods , Norovirus/isolation & purification , Real-Time Polymerase Chain Reaction/methods , Reverse Transcriptase Polymerase Chain Reaction/methods , Adolescent , Adult , Aged , Aged, 80 and over , Caliciviridae Infections/virology , Child , Child, Preschool , False Negative Reactions , Female , Gastroenteritis/virology , Genotype , Humans , Infant , Infant, Newborn , Male , Middle Aged , Norovirus/classification , Norovirus/genetics , Prospective Studies , Sensitivity and Specificity , United States , Young Adult
2.
Clin Obes ; 4(2): 91-100, 2014 Apr.
Article in English | MEDLINE | ID: mdl-25826732

ABSTRACT

This study aimed to assess the effectiveness of a novel, community-based weight management programme delivered through general practitioner (GP) practices and community pharmacies in one city in the United Kingdom. This study used a non-randomized, retrospective, observational comparison of clinical data collected by participating GP practices and community pharmacies. Subjects were 451 overweight or obese men and women resident in areas of high socioeconomic deprivation (82% from black and minority ethnic groups, 86% women, mean age: 41.1 years, mean body mass index [BMI]: 34.5 kg m(-2)). Weight, waist circumference and BMI at baseline, after 12 weeks and after 9 months were measured. Costs of delivery were also analysed. Sixty-four per cent of participants lost weight after the first 12 weeks of the My Choice Weight Management Programme. There was considerable dropout. Mean percentage weight loss (last observation carried forward) was 1.9% at 12 weeks and 1.9% at final follow-up (9 months). There was no significant difference in weight loss between participants attending GP practices and those attending pharmacies at both 12 weeks and at final follow-up. Costs per participant were higher via community pharmacy which was attributable to better attendance at sessions among community pharmacy participants than among GP participants. The My Choice Weight Management Programme produced modest reductions in weight at 12 weeks and 9 months. Such programmes may not be sufficient to tackle the obesity epidemic.


Subject(s)
Community Pharmacy Services/organization & administration , Obesity/therapy , Primary Health Care/organization & administration , Weight Reduction Programs , Adult , Community Pharmacy Services/economics , Female , Humans , Male , Middle Aged , Obesity/epidemiology , Primary Health Care/economics , United Kingdom/epidemiology , Weight Loss
3.
Analyst ; 136(4): 801-6, 2011 Feb 21.
Article in English | MEDLINE | ID: mdl-21152628

ABSTRACT

Cavity enhanced absorption measurements have been made of several species that absorb light between 1.5 and 1.7 µm using both a supercontinuum source and superluminescent light emitting diodes. A system based upon an optical enhancement cavity of relatively high finesse, consisting of mirrors of reflectivity ∼99.98%, and a Fourier transform spectrometer, is demonstrated. Spectra are recorded of isoprene, butadiene, acetone and methane, highlighting problems with spectral interference and unambiguous concentration determinations. Initial results are presented of acetone within a breath-like matrix indicating ppm precision at <∼10 ppm acetone levels. Instrument sensitivities are sufficiently enhanced to enable the detection of atmospheric levels of methane. Higher detection sensitivities are achieved using the supercontinuum source, with a minimum detectable absorption coefficient of ∼4 × 10(-9) cm(-1) reported within a 4 min acquisition time. Finally, two superluminescent light emitting diodes are coupled together to increase the wavelength coverage, and measurements are made simultaneously on acetylene, CO(2), and butadiene. The absorption cross-sections for acetone and isoprene have been measured with an instrumental resolution of 4 cm(-1) and are found to be 1.3 ± 0.1 × 10(-21) cm(2) at a wavelength of 1671.9 nm and 3.6 ± 0.2 × 10(-21) cm(2) at 1624.7 nm, respectively.


Subject(s)
Breath Tests/methods , Infrared Rays , Spectroscopy, Fourier Transform Infrared/methods , Absorption , Breath Tests/instrumentation , Humans , Spectroscopy, Fourier Transform Infrared/instrumentation
4.
Analyst ; 134(11): 2220-3, 2009 Nov.
Article in English | MEDLINE | ID: mdl-19838407

ABSTRACT

A fibre coupled near-infrared superluminescent light emitting diode that emits approximately 10 mW of radiation between 1.62 and 1.7 microm is employed in combination with a broad-band cavity enhanced spectrometer consisting of a linear optical cavity with mirrors of reflectivity approximately 99.98% and either a dispersive near-infrared spectrometer or a Fourier transform interferometer. Results are presented on the absorption of 1,3-butadiene, and sensitivities are achieved of 6.1 x 10(-8) cm(-1) using the dispersive spectrometer in combination with phase-sensitive detection, and 1.5 x 10(-8) cm(-1) using the Fourier transform interferometer (expressed as a minimum detectable absorption coefficient) over several minutes of acquisition time.


Subject(s)
Luminescence , Spectrophotometry, Infrared/instrumentation , Spectrophotometry, Infrared/methods , Absorption , Air Pollutants/chemistry , Butadienes/chemistry , Electrodes , Industry , Spectroscopy, Fourier Transform Infrared
5.
Neuroimage ; 42(2): 467-73, 2008 Aug 15.
Article in English | MEDLINE | ID: mdl-18599315

ABSTRACT

Despite considerable research, effective and safe treatments for human pain disorders remain elusive. Understanding the biology of different human pain conditions and researching effective treatments continue to be dominated by animal models, some of which are of limited value. British and European legislation demands that non-animal approaches should be considered before embarking on research using experimental animals. Recent scientific and technical developments, particularly in human neuroimaging, offer the potential to replace some animal procedures in the study of human pain. A group of pain research experts from academia and industry met with the aim of exploring creatively the tools, strategies and challenges of replacing some animal experiments in pain research with ethically conducted studies of human patients and healthy volunteers, in combination with in vitro methods. This report considers how a range of neuroimaging techniques including functional magnetic resonance imaging, magnetoencephalography and positron emission tomography, singly and combined, can address human pain conditions. In addition, microdialysis in human subjects; genome-wide association research, twin studies and other epidemiological approaches; and in vitro cell and tissue research, are examined for their replacement potential in combination with neuroimaging. Recommendations highlight further opportunities to advance the replacement of animal studies with robust methods of relevance to understanding and treating human pain.


Subject(s)
Clinical Trials as Topic/methods , Diagnostic Imaging/methods , Pain Management , Pain/diagnosis , Animal Experimentation , Education , Healthy Volunteers , Human Experimentation , Humans , United Kingdom
6.
Rheumatology (Oxford) ; 43(9): 1167-72, 2004 Sep.
Article in English | MEDLINE | ID: mdl-15213334

ABSTRACT

OBJECTIVE: To quantify the set-up costs and monetary benefits of a welfare rights service integrated within an NHS service provider, that selects eligible patients using the Health Assessment Questionnaire (HAQ) and offers welfare rights advice to assist in application for Disability Living Allowance and Attendance Allowance. METHOD: (1) DESIGN: a cost evaluation of a social intervention, screening with the HAQ and welfare rights advice in primary care and hospital settings. (2) SETTING: Eight general practices and four hospital rheumatology out-patient departments were selected from four localities in the southwest of England. (3) PARTICIPANTS: Two hundred and sixty-eight eligible patients with arthritis accepted an interview with a welfare rights officer (WRO) from a sample of 1989 service users identified from GPs' records and hospital out-patient lists. Two hundred and forty two service users expressed an interest in take up of the social intervention. (4) Service users with a HAQ score >/=1.5 were contacted by telephone and offered an appointment with an experienced WRO to help them complete a welfare benefit application form. A 'micro-costing' study was undertaken with assessment of monetary benefits received. RESULTS: The indicative set-up costs of similar welfare rights services are pound 8125 in a GP setting and pound 9307 per annum in a hospital setting at 2002 prices. Total annual unclaimed Disability Living Allowance/Attendance Allowance granted to successful claimants was pound 184,382 in the GP setting (n = 84 from 137) and pound 169,309 in the hospital setting (n = 79 from 131). CONCLUSIONS: Welfare rights advice received during a visit to a GP practice or a hospital out-patient department can substantially reduce the level of unclaimed benefit in arthritic populations including the elderly; with mobility and care difficulties. A welfare rights service integrated within a GP practice or hospital that screens people with arthritis using HAQ scores and encourages those with scores >/=1.5 to see a WRO for help with welfare benefit confers monetary benefits for service users that substantially outweigh set-up costs.


Subject(s)
Arthritis/economics , Social Security/economics , Aged , Ambulatory Care/economics , Arthritis, Rheumatoid/economics , Costs and Cost Analysis/methods , Delivery of Health Care, Integrated/economics , England , Family Practice/economics , Female , Humans , Male , Osteoarthritis/economics , State Medicine , Surveys and Questionnaires
7.
Rheumatology (Oxford) ; 43(7): 863-8, 2004 Jul.
Article in English | MEDLINE | ID: mdl-15113991

ABSTRACT

OBJECTIVES: To test, in a variety of health settings, the ability of the Health Assessment Questionnaire (HAQ) disability index to predict the eligibility of patients with moderate or severe arthritis for disability living allowance or attendance allowance. METHODS: The study included patients from 20 general practices and four hospital out-patient departments across four areas in the southwest of England. Adults with an established diagnosis of rheumatoid arthritis, or osteoarthritis of the hip or knee, and who were not in receipt of Disability Living Allowance (DLA) or Attendance Allowance (AA) were sent an HAQ. Those who scored 1.5 or more were offered an appointment with a welfare advice worker at which they completed an application for DLA or AA. After 3 months they were contacted by the advice worker and asked about the outcome of their applications. RESULTS: Over half of those who completed an HAQ scored 1.5 or over (moderate to severe disability as measured by the HAQ) and were offered advice from experienced welfare benefits advisors. Of these, 87% applied for DLA or AA. Sixty-nine per cent of the applicants were successful. Those scoring 1.75 and over were more likely to be awarded benefit (73% success CLs 67, 79) than people scoring between 1.5 and 1.625 where 55% (CLs 41,69) of applicants were successful. CONCLUSION: The HAQ was shown to be a good predictor of eligibility for AA or DLA. It can be used, in a variety of health settings, to indicate patients who, with help from an experienced advisor, are likely to gain increased financial help.


Subject(s)
Arthritis , Disability Evaluation , Social Welfare , Aged , England , Female , Health Status Indicators , Humans , Male , Middle Aged , Surveys and Questionnaires
8.
Rheumatology (Oxford) ; 41(1): 100-2, 2002 Jan.
Article in English | MEDLINE | ID: mdl-11792887

ABSTRACT

BACKGROUND: Many eligible people with arthritis do not receive disability benefits. Application forms are lengthy and complex, and doctors and nurses are often unsure which patients would qualify. AIM: To investigate how severe disability on the Health Assessment Questionnaire (HAQ) relates to successful application for disability benefits by people with osteoarthritis (OA) and rheumatoid arthritis (RA). METHOD: RA patients attending a hospital out-patient rheumatology clinic and patients with OA or RA in two general practices completed an HAQ and were asked about receipt of disability benefits. Those scoring 2 or more on the HAQ (severe disability) and not in receipt of benefits were offered professional help to complete applications for Disability Living Allowance (DLA) or Attendance Allowance (AA). RESULTS: Eighty per cent of patients with an HAQ score of 2 or more were already in receipt of benefits. Seventy-nine per cent of the new applicants applied successfully, the average benefit being in excess of 2580 pounds per annum. CONCLUSION: This initial study suggests that people who score 2 or more on the HAQ should be encouraged to apply for disability benefits. A test of the generalizability of these findings and the success rate associated with lower HAQ scores should be undertaken.


Subject(s)
Disability Evaluation , Health Status Indicators , Social Welfare/statistics & numerical data , Adult , Aged , Arthritis, Rheumatoid , Female , Humans , Male , Middle Aged , Osteoarthritis , Sampling Studies , Sensitivity and Specificity , Surveys and Questionnaires , United Kingdom
9.
Sex Transm Dis ; 28(9): 497-503, 2001 Sep.
Article in English | MEDLINE | ID: mdl-11518865

ABSTRACT

BACKGROUND AND GOAL: In areas with persistent syphilis, to characterize persons at higher risk for transmitting syphilis. STUDY DESIGN: Cohort study. Structured interviews of persons with early syphilis from four research centers were linked to outcomes of partner tracing. RESULTS: Of 743 persons with syphilis, 229 (31%) reported two or more partners in the previous month, and 57 (8%) received money or drugs for sex in the previous three months. Persons with at least one partner at an earlier stage of syphilis than themselves were defined as transmitters; 63 (8.5%) of persons with early syphilis met this definition. Having concurrent partners (two or more in one week in the last month) was independently associated with being a transmitter. CONCLUSION: Sexual network/behavioral characteristics of syphilis patients and their partners, such as concurrency, can help identify persons at higher risk for transmitting syphilis who should receive emphasis in disease prevention activities.


Subject(s)
Sexual Behavior/statistics & numerical data , Sexual Partners , Syphilis/transmission , Adult , Black or African American/statistics & numerical data , Asian/statistics & numerical data , Cohort Studies , Disease Transmission, Infectious , Female , Government Programs , Humans , Logistic Models , Louisiana/epidemiology , Male , Middle Aged , Mississippi/epidemiology , Risk Assessment , Risk Factors , South Carolina/epidemiology , Syphilis/epidemiology , Syphilis/prevention & control , Texas/epidemiology , White People/statistics & numerical data
10.
Genetics ; 156(4): 1837-52, 2000 Dec.
Article in English | MEDLINE | ID: mdl-11102378

ABSTRACT

Over the last decade, surveys of DNA sequence variation in natural populations of several Drosophila species and other taxa have established that polymorphism is reduced in genomic regions characterized by low rates of crossing over per physical length. Parallel studies have also established that divergence between species is not reduced in these same genomic regions, thus eliminating explanations that rely on a correlation between the rates of mutation and crossing over. Several theoretical models (directional hitchhiking, background selection, and random environment) have been proposed as population genetic explanations. In this study samples from an African population (n = 50) and a European population (n = 51) were surveyed at the su(s) (1955 bp) and su(w(a)) (3213 bp) loci for DNA sequence polymorphism, utilizing a stratified SSCP/DNA sequencing protocol. These loci are located near the telomere of the X chromosome, in a region of reduced crossing over per physical length, and exhibit a significant reduction in DNA sequence polymorphism. Unlike most previously surveyed, these loci reveal substantial skews toward rare site frequencies, consistent with the predictions of directional hitchhiking and random environment models and inconsistent with the general predictions of the background selection model (or neutral theory). No evidence for excess geographic differentiation at these loci is observed. Although linkage disequilibrium is observed between closely linked sites within these loci, many recombination events in the genealogy of the sampled alleles can be inferred and the genomic scale of linkage disequilibrium, measured in base pairs between sites, is the same as that observed for loci in regions of normal crossing over. We conclude that gene conversion must be high in these regions of low crossing over.


Subject(s)
Drosophila Proteins , Drosophila melanogaster/genetics , Models, Genetic , Proteins/genetics , RNA-Binding Proteins/genetics , X Chromosome/genetics , Animals , Base Sequence , Crossing Over, Genetic , DNA/genetics , Gene Frequency , Linkage Disequilibrium , Molecular Sequence Data , Polymorphism, Genetic , Polymorphism, Single-Stranded Conformational , Sequence Alignment , Sequence Homology, Nucleic Acid , Spain , Zimbabwe
11.
Genetics ; 154(3): 1255-69, 2000 Mar.
Article in English | MEDLINE | ID: mdl-10757767

ABSTRACT

A restriction enzyme survey of a 110-kb region including the achaete scute complex (ASC) examined 14 polymorphic molecular markers in a sample of 56 naturally occurring chromosomes. Large insertions as a class were associated with a reduction in both sternopleural and abdominal bristle number, supporting deleterious mutation-selection equilibrium models for the maintenance of quantitative genetic variation. Two polymorphic sites were independently associated with variation in bristle number measured in two genetic backgrounds as assessed by a permutation test. A 6-bp deletion near sc alpha is associated with sternopleural bristle number variation in both sexes and a 3.4-kb insertion between sc beta and sc gamma is associated with abdominal bristle number variation in females. Under an additive genetic model, the small deletion polymorphism near sc alpha accounts for 25% of the total X chromosome genetic variation in sternopleural bristle number, and the 3.4 kb insertion accounts for 22% of the total X chromosome variation in female abdominal bristle number. The observation of common polymorphisms associated with variation in bristle number is more parsimoniously explained by models that incorporate balancing selection or assume variants affecting bristle number are neutral, than mutation-selection equilibrium models.


Subject(s)
DNA Transposable Elements , DNA-Binding Proteins/physiology , Drosophila Proteins , Drosophila melanogaster/physiology , Insect Proteins/physiology , Polymorphism, Genetic , Transcription Factors/physiology , Animals , Basic Helix-Loop-Helix Transcription Factors , DNA-Binding Proteins/genetics , Drosophila melanogaster/anatomy & histology , Drosophila melanogaster/genetics , Female , Insect Proteins/genetics , Mutagenesis, Insertional , Transcription Factors/genetics , X Chromosome
12.
Mol Biol Evol ; 17(4): 645-55, 2000 Apr.
Article in English | MEDLINE | ID: mdl-10742055

ABSTRACT

Nucleotide variation at the alcohol dehydrogenase locus (Adh) was studied in the outcrossing Arabidopsis lyrata, a close relative of the selfing Arabidopsis thaliana. Overall, estimated nucleotide diversity in the North American ssp. lyrata and two European ssp. petraea populations was 0.0038, lower than the corresponding specieswide estimate for A. thaliana at the same set of nucleotide sites. The distribution of segregating sites across the gene differed between the two species. Estimated sequence diversity within an A. lyrata population with a large sample size (0.0023) was much higher than has previously been observed for A. thaliana. This North American population has an excess of sites at intermediate frequencies compared with neutral expectation (Tajima's D = 2.3, P < 0.005), suggestive of linked balancing selection or a recent population bottleneck. In contrast, an excess of rare polymorphisms has been found in A. thaliana. Polymorphism within A. lyrata and divergence from A. thaliana appear to be correlated across the Adh gene sequence. The geographic distribution of polymorphism was quite different from that of A. thaliana, for which earlier studies of several genes found low within-population nucleotide site polymorphism and no overall continental differentiation of variation despite large differences in site frequencies between local populations. Differences between the outcrossing A. lyrata and the selfing A. thaliana reflect the impact of differences in mating system and the influence of bottlenecks in A. thaliana during rapid colonization on DNA sequence polymorphism. The influence of additional variability-reducing mechanisms, such as background selection or hitchhiking, may not be discernible.


Subject(s)
Alcohol Dehydrogenase/genetics , Arabidopsis/genetics , Polymorphism, Genetic , Crosses, Genetic , Genetic Variation , Polymerase Chain Reaction , Polymorphism, Single-Stranded Conformational , Sequence Analysis, DNA
13.
J Health Serv Res Policy ; 5(3): 164-9, 2000 Jul.
Article in English | MEDLINE | ID: mdl-11183627

ABSTRACT

OBJECTIVES: To explore attitudes to and problems experienced with recruitment into randomised trials in cancer care. METHODS: In-depth semi-structured interviews with a purposive sample of 20 hospital clinicians in the South West of England identified from 192 participants in a larger postal survey. Interviews were recorded on audiotape and fully transcribed. Data were analysed by comparing transcripts and describing emergent themes. RESULTS: Clinicians do not always find it easy to identify key randomised trials in their area of interest. Even when they identify those trials in which they would like to participate, they are not always able to recruit patients. Although recruitment can be hindered by the time and administration involved and the resources needed, the attitudes of clinicians to research in general, the design of randomised trials, clinicians' concerns regarding individual patients and patients' preferences for different treatments also present major barriers. Other factors of concern include the imposition of strict eligibility criteria and the expense and complexity of monitoring and follow-up. CONCLUSION: Barriers to recruitment depend on the clinicians' individual situations and on a complex combination of factors. Action is needed to promote awareness of randomised trials under way, to ensure that trials address issues of importance, are acceptable to patients and clinicians, and that practical support is provided for participating centres.


Subject(s)
Attitude of Health Personnel , Neoplasms/therapy , Patient Selection , Physicians/psychology , Randomized Controlled Trials as Topic , England , Humans , Interviews as Topic , Research Support as Topic
16.
Cancer Chemother Pharmacol ; 44(5): 372-80, 1999.
Article in English | MEDLINE | ID: mdl-10501910

ABSTRACT

PURPOSE: To determine toxicities, maximally tolerated dose (MTD), pharmacokinetic profile, and potential antitumor activity of MTA, a novel antifolate compound which inhibits the enzymes thymidylate synthase (TS), glycinamide ribonucleotide formyltransferase (GARFT), and dihydrofolate reductase (DHFR). METHODS: Patients with advanced solid tumors were given MTA intravenously over 10 min every 21 days. Dose escalation was based on the modified continual reassessment method (MCRM), with one patient treated at each minimally toxic dose level. Pharmacokinetic studies were performed in all patients. RESULTS: A total of 37 patients (27 males, 10 females, median age 59 years, median performance status 90%) were treated with 132 courses at nine dose levels, ranging from 50 to 700 mg/m(2). The MTD of MTA was 600 mg/m(2), with neutropenia and thrombocytopenia, and cumulative fatigue as the dose-limiting toxicities. Hematologic toxicity correlated with renal function and mild reversible renal dysfunction was observed in multiple patients. Other nonhematologic toxicities observed included mild to moderate fatigue, anorexia, nausea, diarrhea, mucositis, rash, and reversible hepatic transaminase elevations. Three patients expired due to drug-related complications. Pharmacokinetic analysis during the first course of treatment at the 600 mg/m(2) dose level demonstrated a mean harmonic half-life, maximum plasma concentration (Cpmax), clearance (CL), area under the curve (AUC), and apparent volume of distribution at steady state (Vdss) of 3.08 h, 137 microg/ml, 40.0 ml/min per m(2), 266 microg. h/ml, and 7.0 l/m(2), respectively. An average of 78% of the compound was excreted unchanged in the urine. Partial responses were achieved in two patients with advanced pancreatic cancer and in two patients with advanced colorectal cancer. Minor responses were obtained in six patients with advanced colorectal cancer. CONCLUSIONS: The MTD and dose for phase II clinical trials of MTA when administered intravenously over 10 min every 21 days was 600 mg/m(2). MTA is a promising new anticancer agent.


Subject(s)
Antineoplastic Agents/adverse effects , Antineoplastic Agents/pharmacokinetics , Glutamates/adverse effects , Glutamates/pharmacokinetics , Guanine/analogs & derivatives , Neoplasms/drug therapy , Adult , Aged , Area Under Curve , Colorectal Neoplasms/blood , Colorectal Neoplasms/drug therapy , Colorectal Neoplasms/urine , Creatinine/blood , Dose-Response Relationship, Drug , Drug Administration Schedule , Female , Glutamates/administration & dosage , Guanine/administration & dosage , Guanine/adverse effects , Guanine/pharmacokinetics , Humans , Infusions, Intravenous , Leukocyte Count/drug effects , Male , Middle Aged , Neoplasms/blood , Neoplasms/urine , Pancreatic Neoplasms/blood , Pancreatic Neoplasms/drug therapy , Pancreatic Neoplasms/urine , Pemetrexed , Regression Analysis , Thrombocytopenia/chemically induced
17.
Genome Res ; 9(8): 720-31, 1999 Aug.
Article in English | MEDLINE | ID: mdl-10447507

ABSTRACT

The statistical power of five association study test statistics (two haplotype-based tests, two marker-based tests, and the Transmission Disequilibrium Test-Q5) to detect single nucleotide polymorphism (SNP)/phenotype associations in a linkage-disequilibrium-based candidate gene scan employing a number of SNPs is examined. Power is estimated as a function of realistic parameters expected to affect the likelihood of detecting a significant association: the number of SNPs examined, the scaled recombination size of the region examined, the proportion of variance in the trait attributable to a hidden causative polymorphism within the region, and the number of individuals or families examined. For the different combinations of parameter values, power is estimated from a large number of realizations of a simulated coalescent describing a single random mating population with mutation, random genetic drift, and recombination. This explicit population genetics model results in a distribution of DNA marker heterozygosities and linkage disequilibria that are likely to resemble those expected in actual population samples. The study concludes that (1) marker-based permutation tests are more powerful than simple haplotype-based tests, (2) there is sufficient power to detect the presence of causative polymorphisms of small effect if on the order of 500 individuals are sampled, (3) greater power is achieved by increasing the sample size than by increasing the number of polymorphisms, (4) association studies are generally more powerful than transmission disequilibrium-based tests, and (5) for the range of parameters considered association studies have a low repeatability unless sample sizes are on the order of 500 individuals. Estimates of 4Nc for a number of gene regions and human populations will be of use in determining the density of SNPs that are likely to be required for successful association studies.


Subject(s)
Genetic Variation/genetics , Quantitative Trait, Heritable , Computational Biology/methods , Computational Biology/statistics & numerical data , Genetic Markers/genetics , Genotype , Humans , Linkage Disequilibrium/genetics , Nucleotides/genetics , Phenotype , Polymorphism, Genetic/genetics
18.
Genetics ; 152(4): 1605-14, 1999 Aug.
Article in English | MEDLINE | ID: mdl-10430586

ABSTRACT

Genetic variation in nondisjunction frequency among X chromosomes from two Drosophila melanogaster natural populations is examined in a sensitized assay. A high level of genetic variation is observed (a range of 0.006-0.241). Two naturally occurring variants at the nod locus, a chromokinesin required for proper achiasmate chromosome segregation, are significantly associated with an increased frequency of nondisjunction. Both of these polymorphisms are found at intermediate frequency in widely distributed natural populations. To account for these observations, we propose a general model incorporating unique opportunities for meiotic drive during female meiosis. The oötid competition model can account for both high mean rates of female-specific nondisjunction in Drosophila and humans as well as the standing genetic variation in this critical fitness character in natural populations.


Subject(s)
Drosophila Proteins , Drosophila melanogaster/genetics , Microtubule Proteins/genetics , Nondisjunction, Genetic , Polymorphism, Genetic/genetics , X Chromosome/genetics , Animals , Chromosome Inversion , Crosses, Genetic , Female , Genetic Variation , Kinesins , Male , Temperature
19.
Genetics ; 152(4): 1615-29, 1999 Aug.
Article in English | MEDLINE | ID: mdl-10430587

ABSTRACT

A maximum-likelihood method for the estimation of tetrad frequencies from single-spore data is presented. The multilocus exchange with interference and viability (MEIV) model incorporates a clearly defined model of exchange, interference, and viability whose parameters define a multinomial distribution for single-spore data. Maximum-likelihood analysis of the MEIV model (MEIVLA) allows point estimation of tetrad frequencies and determination of confidence intervals. We employ MEIVLA to determine tetrad frequencies among 15 X chromosomes sampled at random from Drosophila melanogaster natural populations in Africa and North America. Significant variation in the frequency of nonexchange, or E(0) tetrads, is observed within both natural populations. Because most nondisjunction arises from E(0) tetrads, this observation is quite unexpected given both the prevalence and the deleterious consequences of nondisjunction in D. melanogaster. Use of MEIVLA is also demonstrated by reanalyzing a recently published human chromosome 21 dataset. Analysis of simulated datasets demonstrates that MEIVLA is superior to previous methods of tetrad frequency estimation and is particularly well suited to analyze samples where the E(0) tetrad frequency is low and sample sizes are small, conditions likely to be met in most samples from human populations. We discuss the implications of our analysis for determining whether an achiasmate system exists in humans to ensure the proper segregation of E(0) tetrads.


Subject(s)
Chromatids/genetics , Crossing Over, Genetic , Drosophila melanogaster/genetics , Likelihood Functions , Models, Genetic , Animals , Chromosomes/genetics , Chromosomes, Human/genetics , Female , Humans , Male , Sister Chromatid Exchange , X Chromosome/genetics
20.
Br J Gen Pract ; 49(438): 11-5, 1999 Jan.
Article in English | MEDLINE | ID: mdl-10622009

ABSTRACT

BACKGROUND: There is concern about the apparent lack of uptake of management and referral guideline information by general practitioners (GPs) in their day-to-day consultations with patients. Little is understood about the barriers to the uptake of guidelines as perceived by GPs. AIMS: To explore how GPs gain access to and use guidelines, including computer-based guidelines, in day-to-day consultations with their patients; and to identify the perceived problems and barriers to the use of guidelines in such situations. METHOD: Postal questionnaires enquiring about the practices and attitudes towards the use of guidelines in general practice were completed by 391 of 600 randomly selected GPs in the South and West NHS region. RESULTS: GPs found guidelines a useful method of accessing expert information. Key factors in their uptake were brevity, an authoritative and unbiased source of evidence, and resonance with the GP's usual practices; they also needed to be flexible enough to incorporate individual viewpoints. Guidelines were perceived as being valuable to enable safe delegation of care to other health professionals and for sharing decision-making with patients. Dissemination of guidelines through the medium of computers was acceptable to the majority of GPs. Virtually all (93%) responders reported adapting guidelines to the needs of individual patients. Older GPs from non-fundholding practices were least likely to show a positive attitude towards guidelines. CONCLUSION: In principle, there is a very positive attitude towards the use of guidelines in general practice. However, those developing guidelines for use by GPs in the consulting room need to be aware of the factors that facilitate their use in practice. Educational strategies aimed at increasing the use of guidelines need to take into account the significant proportion who show negative attitudes towards guidelines, whose characteristics have been identified in this study.


Subject(s)
Decision Support Techniques , Family Practice/statistics & numerical data , Physicians, Family/psychology , Practice Guidelines as Topic , Attitude of Health Personnel , Humans , United Kingdom
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