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1.
NPJ Prim Care Respir Med ; 34(1): 3, 2024 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-38664469

RESUMO

Respiratory diseases, including asthma and chronic obstructive pulmonary disease (COPD), are common in England with the worst respiratory outcomes observed in the most deprived areas. There is limited published research to establish whether the rate of oral corticosteroid (OCS) prescribing for asthma and COPD is linked to levels of deprivation. This study carried out a multivariable regression analysis of publicly available data and found that deprivation is associated with a statistically significant increase in the proportion of patients receiving an OCS prescription for asthma or COPD at a GP practice level (p < 0.001). The model estimated that the proportion of prescriptions is 1.88% (95% CI 1.83% to 1.92%) and 2.84% (95% CI 2.70% to 2.98%) for the least deprived GP practice and the most deprived GP practice, respectively. This study lays the groundwork for future research using individual patient level data to consider the impact of variation in OCS prescribing rates.


Assuntos
Corticosteroides , Asma , Padrões de Prática Médica , Doença Pulmonar Obstrutiva Crônica , Humanos , Inglaterra/epidemiologia , Asma/tratamento farmacológico , Asma/epidemiologia , Corticosteroides/uso terapêutico , Corticosteroides/administração & dosagem , Doença Pulmonar Obstrutiva Crônica/tratamento farmacológico , Doença Pulmonar Obstrutiva Crônica/epidemiologia , Padrões de Prática Médica/estatística & dados numéricos , Feminino , Masculino , Pessoa de Meia-Idade , Administração Oral , Adulto , Prescrições de Medicamentos/estatística & dados numéricos , Idoso , Adolescente , Adulto Jovem
2.
Pediatr Dermatol ; 40(1): 50-63, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36127813

RESUMO

PURPOSE: To describe secondary care health care resource utilization (HCRU) for children and adolescents with atopic dermatitis (AD). PATIENTS AND METHODS: This UK chart review of patients with moderate-to-severe AD was conducted in four National Health Service hospitals. Cohorts were defined by age (children 6-11 years, adolescents 12-17) at first consultation. Eligible patients were selected consecutively, starting with the most recently consulting patient. At least 12 months' data were abstracted from medical records. Data were collected on HCRU, demographics/clinical characteristics, treatment, and patient-reported outcomes. RESULTS: Data were abstracted for 55 patients. Most patients (80%) had severe AD at first referral, a mean (SD) of 3.2 (10.7) patient-reported flare episodes/patient/year-of-observation, and 18.5 (16.7) tests/scans/procedures/patient/year. Mean (SD) observation duration was 3.6 (1.8) years. Patients had tried mean (SD) 7.9 (5.3) treatments/patient/year of observation. Topical corticosteroids (TCS; 24.5% of prescriptions) were most frequently prescribed. Mean (SD) use of emollients/moisturizers, TCS, systemic corticosteroids, and systemic immunosuppressants was 30.9 (21.3), 21.1 (23.4), 1.7 (8.3), and 7.8 (8.2) months. There was a mean (SD) of 5.3 (2.9) consultations/patient/year-of-observation; 116 (10.7%) for flare. Most hospitalizations (87.5%) were for children; the 8/55 (15%) hospitalized patients (mean 2.0 hospitalizations/patient during observation period) spent 6.2 (SD: 5.1) nights in hospital/hospitalization. Earliest mean (SD) Children's Dermatology Life Quality Index score was 15.3 (7.2); latest was 12.9 (7.5). CONCLUSION: Children and adolescents with moderate-to-severe AD had a high HCRU burden and small changes in quality of life, indicating that current treatments may provide suboptimal AD control in most cases.


Assuntos
Dermatite Atópica , Criança , Humanos , Adolescente , Dermatite Atópica/tratamento farmacológico , Dermatite Atópica/epidemiologia , Medicina Estatal , Qualidade de Vida , Atenção Secundária à Saúde , Corticosteroides/uso terapêutico , Inglaterra/epidemiologia , Índice de Gravidade de Doença
3.
Vaccine ; 40(48): 6939-6946, 2022 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-36280563

RESUMO

OBJECTIVES: This study examined healthcare resource use (HCRU) for selected vaccine-preventable diseases (VPD) in secondary care in England. METHODS: The hospital episode statistics (HES) dataset covering all secondary care interactions within the English National Health Service (NHS) from 2015 to 2021 was used to identify and track HCRU for patients with a primary or secondary diagnosis for pertussis and Haemophilus influenzae type b (Hib), or a primary diagnosis only for hepatitis B, diphtheria, poliomyelitis, or tetanus. The first documented diagnosis during the study period (01/04/2015-31/03/2021) was the index event. RESULTS: 7,274 patients with a total of 5,554,343 patient-days (mean follow up 1,491 days) were included. The total number of hospital admissions was 27,092 and total inpatient cost was £4,987,770, with hepatitis B making up ∼80 % of this. Mean outpatient hospital appointments per patient were highest for tetanus (4.00), but total outpatient A&E cost burden was highest for Hib (£643,343 [mean per attendance £144.57]). For patients 0-9 years of age (n = 1,917), pertussis (n = 1,547) and Hib (n = 313) were by far the most commonly coded diseases. Hepatitis B was the most common disease in adults of working age and Hib was most prevalent in adults of retirement age. Surprisingly, poliomyelitis was observed in the database potentially due to historic diagnoses and/or coding inaccuracy. Other discrepancies with surveillance data were noted. CONCLUSIONS: VPDs impose a large burden on the NHS, but there is potential to reduce this and improve public health by optimising vaccination schedules, improving access and ensuring high coverage rates.


Assuntos
Infecções por Haemophilus , Vacinas Anti-Haemophilus , Haemophilus influenzae tipo b , Hepatite B , Poliomielite , Tétano , Doenças Preveníveis por Vacina , Coqueluche , Adulto , Humanos , Lactente , Coqueluche/epidemiologia , Coqueluche/prevenção & controle , Vacinas contra Hepatite B , Vacinas Combinadas , Atenção Secundária à Saúde , Medicina Estatal , Infecções por Haemophilus/epidemiologia , Vacina contra Difteria, Tétano e Coqueluche
4.
Clinicoecon Outcomes Res ; 14: 167-177, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35399649

RESUMO

Background: Whilst there is international evidence around the high healthcare resource utilization (HRU) associated with atopic dermatitis (AD), there is a lack of published data from the United Kingdom (UK). Methods: A retrospective, descriptive, observational study was conducted to evaluate the burden of moderate-to-severe AD on the National Health Service (NHS) in an adult UK population treated with traditional standard of care prior to the introduction of biologics. Patients (n=59) were recruited from 6 UK NHS Hospital Trusts and observed over three years. Results: 707 dermatology clinic visits were recorded over the observation period, amounting to 6.6 visits per patient-year, most commonly for routine check-ups most of which involved dermatology consultants (n=469, 66%). Physicians were the most consulted healthcare professional (n=652, 92%); emollients were the most common treatment (n=80 courses). 174 flares requiring additional medical advice were recorded in total (1.6 per patient-year). Discussion/Conclusions: Complex treatment pathways for adult patients in the UK with moderate-to-severe AD incur considerable HRU, particularly for those patients non-responsive to systemic therapies with broad immunosuppressant action. Recent advances in biologics-based AD management could possibly have a significant positive impact on HRU through significant reduction in the number of NHS touch points identified in this study.

6.
Diabetes Ther ; 12(12): 3217-3230, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34714523

RESUMO

INTRODUCTION: A cost-effectiveness analysis was conducted comparing a fixed-ratio combination (FRC) of insulin glargine 100 units/mL plus lixisenatide (iGlarLixi) versus the FRC of insulin degludec plus liraglutide (iDegLira) and the free-combination comparators insulin glargine plus dulaglutide (iGlar plus Dula) and basal insulin plus liraglutide (BI plus Lira). METHODS: The IQVIA Core Diabetes Model was used to estimate lifetime costs and outcomes for a cohort of patients with type 2 diabetes mellitus (T2DM) from the UK healthcare perspective. Initial clinical data for iGlarLixi were based on the randomized, controlled LixiLan-L trial and the relative treatment effects for comparators were based on an indirect treatment comparison using data from the AWARD-9 (iGlar plus Dula), LIRA ADD2 BASAL (BI plus Lira), and DUAL V (iDegLira) trials. Costs were derived from publicly available sources. Lifetime costs (in British Pound Sterling [£]) and quality-adjusted life-years (QALYs) were predicted; net monetary benefit (NMB) for iGlarLixi versus comparators was derived using a willingness-to-pay threshold of £20,000. Extensive scenario and sensitivity analyses were conducted. RESULTS: Estimated costs were lowest with iGlarLixi (£31,295) compared with iGlar plus Dula (£38,790), iDegLira (£40,179), and BI plus Lira (£42,467). Total QALYs gained were identical with iGlarLixi and iDegLira (8.438), and comparable with iGlar plus Dula (8.439) and BI plus Lira (8.466). NMB for iGlarLixi was positive versus all comparators (£10,603.86 vs. BI plus Lira; £7,466.24 vs. iGlar plus Dula; £8.874.11 vs. iDegLira). CONCLUSION: In patients with T2DM with suboptimal glycemic control on basal insulin, iGlarLixi provides very similar outcomes and substantial cost savings, compared with other fixed and free combinations of insulins plus glucagon-like peptide-1 receptor agonists.

7.
Curr Med Res Opin ; 36(7): 1209-1224, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32345060

RESUMO

Objective: Health utility estimates for children and adolescents are critical for cost-utility analyses informing health technology assessment (HTA) authorities' decisions governing access to pediatric treatments. However, in a recent review, only 29% of published pediatric cost-utility models used a utility measure validated for children. We examined utility estimates used in pediatric HTAs.Methods: A targeted review of pediatric HTAs was performed, focusing on agencies reporting utility estimate sources and methods.Results: Searches identified 11 HTAs in pediatric indications and five in mixed populations with separate analyses for adults and children. Among 13 appraisals reporting methodological detail, five used pediatric utility estimates (based on the Health Utilities Index [HUI], n = 3; Atopic Dermatitis Quality of Life [ADQoL], n = 1; or mapping, n = 1). Issues were identified with mapping, use of adult data for some health states, and assumptions about ADQoL responses. In the remaining eight appraisals, adult utility estimates were applied. Caregiver utility was included in two of 16 appraisals.Conclusions: Only 38% of pediatric HTAs reviewed used pediatric utility estimates, and HTA authorities raised concerns about these data in many cases; only 12% of HTAs included caregiver utility. Although several preference-based utility measures are available for pediatric populations, limited data and guidance on selection of measures are available. When estimating pediatric utility weights, alternative measures should be reviewed for suitability given the model population and health condition. Pediatric and adult utility estimates should be applied appropriately as patients age over time, and caregiver and/or family member utility should be included, where relevant. Gaps exist in utility measures for children aged <4 years and caregivers.


Assuntos
Avaliação da Tecnologia Biomédica/métodos , Adolescente , Adulto , Criança , Pré-Escolar , Análise Custo-Benefício , Humanos , Qualidade de Vida
8.
J Dermatolog Treat ; 31(8): 815-820, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31305182

RESUMO

Background: There is limited understanding on patterns of systemic treatment in adults with moderate-to-severe atopic dermatitis (AD) in the UK.Objective: To characterize treatment patterns in adult AD patients prescribed immunosuppressants (IMMs) in the primary care setting.Results: Six hundred and fifty-six patients with AD (6.6%) were prescribed IMM in the analysis (mean age 52.1 years; 59.1% female; age-adjusted Charlson comorbidity index 1.4). Most prevalent (>5%) conditions at baseline were depression (10.8%), contact dermatitis (10.7%), rheumatological disease (7.9%), skin/subcutaneous tissue disorders (6.4%), upper respiratory disease (5.8%), and psoriasis (5.2%). At baseline, up to 50% of patients were prescribed ≥1 IMM. During follow-up, 42.7% of patients were prescribed oral corticosteroids (OCSs), increasing in line with IMM exposure. The most commonly prescribed IMM was methotrexate (43.3%). Ciclosporin, the only approved IMM for AD, was prescribed to 16.9% of patients.Conclusions: The prevalence of comorbidities and high rate of IMM prescriptions demonstrate the impact of AD on quality of life. The frequency of OCS prescribing in AD patients treated with IMMs suggests a lack of disease control with existing therapies, and an unmet need for safe and effective targeted agents for long-term disease control.


Assuntos
Ciclosporina/uso terapêutico , Dermatite Atópica/tratamento farmacológico , Imunossupressores/uso terapêutico , Metotrexato/uso terapêutico , Corticosteroides/uso terapêutico , Adulto , Bases de Dados Factuais , Dermatite Atópica/complicações , Dermatite de Contato/complicações , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Psoríase/complicações , Qualidade de Vida , Estudos Retrospectivos , Febre Reumática/complicações , Reino Unido
9.
Proc Biol Sci ; 286(1896): 20182541, 2019 02 13.
Artigo em Inglês | MEDLINE | ID: mdl-30963935

RESUMO

A fundamental question about adaptation in a population is the time of onset of the selective pressure acting on beneficial alleles. Inferring this time, in turn, depends on the selection model. We develop a framework of approximate Bayesian computation (ABC) that enables the use of the full site frequency spectrum and haplotype structure to test the goodness-of-fit of selection models and estimate the timing of selection under varying population size scenarios. We show that our method has sufficient power to distinguish natural selection from neutrality even if relatively old selection increased the frequency of a pre-existing allele from 20% to 50% or from 40% to 80%. Our ABC can accurately estimate the time of onset of selection on a new mutation. However, estimates are prone to bias under the standing variation model, possibly due to the uncertainty in the allele frequency at the onset of selection. We further extend our approach to take advantage of ancient DNA data that provides information on the allele frequency path of the beneficial allele. Applying our ABC, including both modern and ancient human DNA data, to four pigmentation alleles in Europeans, we detected selection on standing variants that occurred after the dispersal from Africa even though models of selection on a new mutation were initially supported for two of these alleles without the ancient data.


Assuntos
DNA Antigo/análise , Frequência do Gene , Haplótipos/genética , Migração Humana , Seleção Genética , Pigmentação da Pele/genética , Teorema de Bayes , Europa (Continente) , Humanos , Modelos Genéticos , Densidade Demográfica , Fatores de Tempo
10.
Qual Life Res ; 28(9): 2373-2381, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30945132

RESUMO

PURPOSE: Management of atopic dermatitis (AD) typically requires application of topical treatments, often multiple times a day. The cosmetic properties and burdensome application of these treatments can be detrimental to quality of life (QoL). Patients who achieve good disease control through use of systemic therapies may reduce the frequency and amount of topical applications, improving QoL. This study aimed to quantify the utility and disutility for topical AD treatment processes. METHODS: Seven vignettes describing different skincare regimens for people with moderate-to-severe AD were developed with input from healthcare professionals. 484 respondents from the general population completed time trade-off items for each vignette. Utility values for each regimen, and disutilities associated with the impact of changes to skincare regimens, were calculated. Analysis of variance assessed differences between skincare regimens. RESULTS: As skincare regimens increased in intensity (0.7968 for the most intense; 0.9999 for the least), utility values decreased. There were no statistically significant differences between skincare regimens followed by patients with good disease control (0.9862 to 0.9999); however, when compared to those involving topical corticosteroids and emollient combinations (0.7968 to 0.8835), significant differences were observed (p < 0.001). The largest disutilities (0.1521 to 0.1705) were between skincare regimens describing the use of topical corticosteroids plus emollient and those followed by patients with good disease control. CONCLUSIONS: The application of topical treatments has a detrimental effect on QoL, which increases with the duration and frequency of applications. Further research is needed to investigate how health and process utilities interact and both can be integrated into medical decision-making.


Assuntos
Dermatite Atópica/terapia , Qualidade de Vida/psicologia , Administração Tópica , Adolescente , Adulto , Idoso , Dermatite Atópica/patologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
11.
Adv Simul (Lond) ; 3: 14, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30038804

RESUMO

BACKGROUND: Learning the skills required for open surgery is essential for trainee progression towards more advanced technical procedures. Simulation supports skill enhancement at a time when exposure to actual surgical procedures and traditional apprentice-based teaching has declined. The proliferation of smartphone and tablet devices with rich, touch sensitive displays and increasing processing power makes a compelling argument for expanding accessibility further by development of mobile virtual simulations for training on demand in any setting, at any time.We present a tablet-based mobile simulation App for educating surgical trainees in the planning and surgical procedures involved in facial lesion resection and local skin flap surgery. METHODS: Novel algorithms were developed and modules included in a mobile simulation App to teach concepts required for three defect reconstruction techniques: elliptical closure, bilateral advancement (H flap) and the semi-circular rotation flap, with additional resources such as videos and formal guidelines made available at relevant points in the simulation. A randomised educational trial was conducted using the mobile simulation App with 18 medical students that were divided equally into two groups: the intervention group learning using the new mobile simulation App, and a control group, undergoing traditional text-based self-study. The students were then assessed on knowledge and skills' acquisition through an MCQ and a task analysis score. RESULTS: There was a statistically significant difference between the scores of students in the intervention group and the students in the non-intervention group in both forms of assessment, with an average multiple-choice assessment score of 62.95% points versus 56.73%, respectively (p = 0.0285), and an average task analysis score of 3.53 versus 2.58, respectively (p = 0.0139). CONCLUSIONS: Touch-based simulation provided an efficient and superior method of learning three different local flap techniques for facial soft tissue reconstruction, and helped recalling steps involved in the surgery in a fluid manner that also improved task performance.

12.
PLoS Biol ; 16(3): e2002985, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29547617

RESUMO

Human genome-wide association studies (GWASs) are revealing the genetic architecture of anthropomorphic and biomedical traits, i.e., the frequencies and effect sizes of variants that contribute to heritable variation in a trait. To interpret these findings, we need to understand how genetic architecture is shaped by basic population genetics processes-notably, by mutation, natural selection, and genetic drift. Because many quantitative traits are subject to stabilizing selection and because genetic variation that affects one trait often affects many others, we model the genetic architecture of a focal trait that arises under stabilizing selection in a multidimensional trait space. We solve the model for the phenotypic distribution and allelic dynamics at steady state and derive robust, closed-form solutions for summary statistics of the genetic architecture. Our results provide a simple interpretation for missing heritability and why it varies among traits. They predict that the distribution of variances contributed by loci identified in GWASs is well approximated by a simple functional form that depends on a single parameter: the expected contribution to genetic variance of a strongly selected site affecting the trait. We test this prediction against the results of GWASs for height and body mass index (BMI) and find that it fits the data well, allowing us to make inferences about the degree of pleiotropy and mutational target size for these traits. Our findings help to explain why the GWAS for height explains more of the heritable variance than the similarly sized GWAS for BMI and to predict the increase in explained heritability with study sample size. Considering the demographic history of European populations, in which these GWASs were performed, we further find that most of the associations they identified likely involve mutations that arose shortly before or during the Out-of-Africa bottleneck at sites with selection coefficients around s = 10-3.


Assuntos
Estatura/genética , Índice de Massa Corporal , Estudo de Associação Genômica Ampla , Modelos Genéticos , Locos de Características Quantitativas , Deriva Genética , Variação Genética , Genética Populacional , Humanos , Fenótipo , Seleção Genética
14.
Behav Brain Sci ; 40: e295, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-29342723

RESUMO

As Branigan & Pickering (B&P) argue, structural priming has important implications for the theory of language structure, but these implications go beyond those suggested. Priming implies a network structure, so the grammar must be a network and so must sentence structure. Instead of phrase structure, the most promising model for syntactic structure is enriched dependency structure, as in Word Grammar.


Assuntos
Linguística , Semântica , Idioma , Rede Social
15.
PLoS One ; 11(4): e0154391, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27104621

RESUMO

The primary aim of this study was to measure HIV-1 persistence following combination antiretroviral therapy (cART) in infants and children. Peripheral blood mononuclear cell (PBMC) HIV-1 DNA was quantified prior to and after 1 year of cART in 30 children, stratified by time of initiation (early, age <3 months, ET; late, age >3 months-2 years, LT). Pre-therapy PBMC HIV-1 DNA levels correlated with pre-therapy plasma HIV-1 levels (r = 0.59, p<0.001), remaining statistically significant (p = 0.002) after adjustment for prior perinatal antiretroviral exposure and age at cART initiation. PBMC HIV-1 DNA declined significantly after 1 year of cART (Overall: -0.91±0.08 log10 copies per million PBMC, p<0.001; ET: -1.04±0.11 log10 DNA copies per million PBMC, p<0.001; LT: -0.74 ±0.13 log10 DNA copies per million PBMC, p<0.001) but rates of decline did not differ significantly between ET and LT. HIV-1 replication exposure over the first 12 months of cART, estimated as area-under-the-curve (AUC) of circulating plasma HIV-1 RNA levels, was significantly associated with PBMC HIV-1 DNA at one year (r = 0.51, p = 0.004). In 21 children with sustained virologic suppression after 1 year of cART, PBMC HIV-1 DNA levels continued to decline between years 1 and 4 (slope -0.21 log10 DNA copies per million PBMC per year); decline slopes did not differ significantly between ET and LT. PBMC HIV-1 DNA levels at 1 year and 4 years of cART correlated with age at cART initiation (1 year: p = 0.04; 4 years: p = 0.03) and age at virologic control (1 and 4 years, p = 0.02). Altogether, these data indicate that reducing exposure to HIV-1 replication and younger age at cART initiation are associated with lower HIV-1 DNA levels at and after one year of age, supporting the concept that HIV-1 diagnosis and cART initiation in infants should occur as early as possible.


Assuntos
Antirretrovirais/uso terapêutico , DNA Viral/antagonistas & inibidores , Infecções por HIV/tratamento farmacológico , HIV-1/efeitos dos fármacos , RNA Viral/antagonistas & inibidores , Replicação Viral/efeitos dos fármacos , Terapia Antirretroviral de Alta Atividade , Pré-Escolar , Variações do Número de Cópias de DNA , DNA Viral/biossíntese , DNA Viral/genética , Feminino , Infecções por HIV/diagnóstico , Infecções por HIV/virologia , HIV-1/fisiologia , Humanos , Lactente , Leucócitos Mononucleares/efeitos dos fármacos , Leucócitos Mononucleares/virologia , Estudos Longitudinais , Masculino , RNA Viral/biossíntese , RNA Viral/genética , Tempo para o Tratamento , Resultado do Tratamento , Carga Viral/efeitos dos fármacos , Replicação Viral/genética
16.
Mol Biol Evol ; 33(3): 657-69, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26545921

RESUMO

Genetic variation harbors signatures of natural selection driven by selective pressures that are often unknown. Estimating the ages of selection signals may allow reconstructing the history of environmental changes that shaped human phenotypes and diseases. We have developed an approximate Bayesian computation (ABC) approach to estimate allele ages under a model of selection on new mutations and under demographic models appropriate for human populations. We have applied it to two resequencing data sets: An ultra-high depth data set from a relatively small sample of unrelated individuals and a lower depth data set in a larger sample with transmission information. In addition to evaluating the accuracy of our method based on simulations, for each SNP, we assessed the consistency between the posterior probabilities estimated by the ABC approach and the ancient DNA record, finding good agreement between the two types of data and methods. Applying this ABC approach to data for eight single nucleotide polymorphisms (SNPs), we were able to rule out an onset of selection prior to the dispersal out-of-Africa for three of them and more recent than the spread of agriculture for an additional three SNPs.


Assuntos
Genética Populacional , Modelos Genéticos , Seleção Genética , Alelos , Teorema de Bayes , Biologia Computacional/métodos , Simulação por Computador , Evolução Molecular , Frequência do Gene , Variação Genética , Humanos , Polimorfismo de Nucleotídeo Único , Análise de Sequência de DNA
17.
Proc Natl Acad Sci U S A ; 112(47): E6496-505, 2015 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-26561581

RESUMO

The prevailing view that the evolution of cells in a tumor is driven by Darwinian selection has never been rigorously tested. Because selection greatly affects the level of intratumor genetic diversity, it is important to assess whether intratumor evolution follows the Darwinian or the non-Darwinian mode of evolution. To provide the statistical power, many regions in a single tumor need to be sampled and analyzed much more extensively than has been attempted in previous intratumor studies. Here, from a hepatocellular carcinoma (HCC) tumor, we evaluated multiregional samples from the tumor, using either whole-exome sequencing (WES) (n = 23 samples) or genotyping (n = 286) under both the infinite-site and infinite-allele models of population genetics. In addition to the many single-nucleotide variations (SNVs) present in all samples, there were 35 "polymorphic" SNVs among samples. High genetic diversity was evident as the 23 WES samples defined 20 unique cell clones. With all 286 samples genotyped, clonal diversity agreed well with the non-Darwinian model with no evidence of positive Darwinian selection. Under the non-Darwinian model, MALL (the number of coding region mutations in the entire tumor) was estimated to be greater than 100 million in this tumor. DNA sequences reveal local diversities in small patches of cells and validate the estimation. In contrast, the genetic diversity under a Darwinian model would generally be orders of magnitude smaller. Because the level of genetic diversity will have implications on therapeutic resistance, non-Darwinian evolution should be heeded in cancer treatments even for microscopic tumors.


Assuntos
Evolução Biológica , Variação Genética , Neoplasias/genética , Neoplasias/patologia , Seleção Genética , Idoso , Sequência de Bases , Contagem de Células , Linhagem Celular Tumoral , Células Clonais , Simulação por Computador , Biblioteca Gênica , Genes Neoplásicos , Genótipo , Humanos , Masculino , Microdissecção , Modelos Genéticos , Dados de Sequência Molecular , Mutação , Taxa de Mutação , Polimorfismo de Nucleotídeo Único/genética , Reprodutibilidade dos Testes , Análise de Sequência de DNA
18.
PLoS One ; 10(7): e0118087, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26197064

RESUMO

The sample frequency spectrum is an informative and frequently employed approach for summarizing DNA variation data. Under the standard neutral model the expectation of the sample frequency spectrum has been derived by at least two distinct approaches. One relies on using results from diffusion approximations to the Wright-Fisher Model. The other is based on Pólya urn models that correspond to the standard coalescent model. A new proof of the expected frequency spectrum is presented here. It is a proof by induction and does not require diffusion results and does not require the somewhat complex sums and combinatorics of the derivations based on urn models.


Assuntos
Variação Genética , Algoritmos , Modelos Genéticos , Análise de Sequência de DNA/métodos
19.
Nature ; 512(7515): 436-440, 2014 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-25043057

RESUMO

Plant resistance (R) genes are a crucial component in plant defence against pathogens. Although R genes often fail to provide durable resistance in an agricultural context, they frequently persist as long-lived balanced polymorphisms in nature. Standard theory explains the maintenance of such polymorphisms through a balance of the costs and benefits of resistance and virulence in a tightly coevolving host-pathogen pair. However, many plant-pathogen interactions lack such specificity. Whether, and how, balanced polymorphisms are maintained in diffusely interacting species is unknown. Here we identify a naturally interacting R gene and effector pair in Arabidopsis thaliana and its facultative plant pathogen, Pseudomonas syringae. The protein encoded by the R gene RPS5 recognizes an AvrPphB homologue (AvrPphB2) and exhibits a balanced polymorphism that has been maintained for over 2 million years (ref. 3). Consistent with the presence of an ancient balanced polymorphism, the R gene confers a benefit when plants are infected with P. syringae carrying avrPphB2 but also incurs a large cost in the absence of infection. RPS5 alleles are maintained at intermediate frequencies in populations globally, suggesting ubiquitous selection for resistance. However, the presence of P. syringae carrying avrPphB is probably insufficient to explain the RPS5 polymorphism. First, avrPphB homologues occur at very low frequencies in P. syringae populations on A. thaliana. Second, AvrPphB only rarely confers a virulence benefit to P. syringae on A. thaliana. Instead, we find evidence that selection for RPS5 involves multiple non-homologous effectors and multiple pathogen species. These results and an associated model suggest that the R gene polymorphism in A. thaliana may not be maintained through a tightly coupled interaction involving a single coevolved R gene and effector pair. More likely, the stable polymorphism is maintained through complex and diffuse community-wide interactions.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Arabidopsis/microbiologia , Evolução Molecular , Interações Hospedeiro-Patógeno/genética , Polimorfismo Genético , Pseudomonas syringae/genética , Seleção Genética/genética , Alelos , Proteínas de Arabidopsis/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Genes de Plantas/genética , Modelos Genéticos , Imunidade Vegetal/genética , Pseudomonas syringae/patogenicidade , Virulência/genética
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