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1.
Am J Respir Crit Care Med ; 205(6): 700-710, 2022 03 15.
Artículo en Inglés | MEDLINE | ID: mdl-34913853

RESUMEN

Rationale: Normal values for FEV1 and FVC are currently calculated using cross-sectional reference equations that include terms for race/ethnicity, an approach that may reinforce disparities and is of unclear clinical benefit. Objectives: To determine whether race/ethnicity-based spirometry reference equations improve the prediction of incident chronic lower respiratory disease (CLRD) events and mortality compared with race/ethnicity-neutral equations. Methods: The MESA Lung Study, a population-based, prospective cohort study of White, Black, Hispanic, and Asian adults, performed standardized spirometry from 2004 to 2006. Predicted values for spirometry were calculated using race/ethnicity-based equations following guidelines and, alternatively, race/ethnicity-neutral equations without terms for race/ethnicity. Participants were followed for events through 2019. Measurements and Main Results: The mean age of 3,344 participants was 65 years, and self-reported race/ethnicity was 36% White, 25% Black, 23% Hispanic, and 17% Asian. There were 181 incident CLRD-related events and 547 deaths over a median of 11.6 years. There was no evidence that percentage predicted FEV1 or FVC calculated using race/ethnicity-based equations improved the prediction of CLRD-related events compared with those calculated using race/ethnicity-neutral equations (difference in C statistics for FEV1, -0.005; 95% confidence interval [CI], -0.013 to 0.003; difference in C statistic for FVC, -0.008; 95% CI, -0.016 to -0.0006). Findings were similar for mortality (difference in C statistics for FEV1, -0.002; 95% CI, -0.008 to 0.003; difference in C statistics for FVC, -0.004; 95% CI, -0.009 to 0.001). Conclusions: There was no evidence that race/ethnicity-based spirometry reference equations improved the prediction of clinical events compared with race/ethnicity-neutral equations. The inclusion of race/ethnicity in spirometry reference equations should be reconsidered.


Asunto(s)
Aterosclerosis , Etnicidad , Adulto , Estudios Transversales , Volumen Espiratorio Forzado , Humanos , Pulmón , Estudios Prospectivos , Valores de Referencia , Espirometría , Capacidad Vital
2.
Thorax ; 76(12): 1219-1226, 2021 12.
Artículo en Inglés | MEDLINE | ID: mdl-33963087

RESUMEN

RATIONALE: Genome-wide association studies (GWASs) have identified numerous loci associated with lower pulmonary function. Pulmonary function is strongly related to smoking and has also been associated with asthma and dust endotoxin. At the individual SNP level, genome-wide analyses of pulmonary function have not identified appreciable evidence for gene by environment interactions. Genetic Risk Scores (GRSs) may enhance power to identify gene-environment interactions, but studies are few. METHODS: We analysed 2844 individuals of European ancestry with 1000 Genomes imputed GWAS data from a case-control study of adult asthma nested within a US agricultural cohort. Pulmonary function traits were FEV1, FVC and FEV1/FVC. Using data from a recent large meta-analysis of GWAS, we constructed a weighted GRS for each trait by combining the top (p value<5×10-9) genetic variants, after clumping based on distance (±250 kb) and linkage disequilibrium (r2=0.5). We used linear regression, adjusting for relevant covariates, to estimate associations of each trait with its GRS and to assess interactions. RESULTS: Each trait was highly significantly associated with its GRS (all three p values<8.9×10-8). The inverse association of the GRS with FEV1/FVC was stronger for current smokers (pinteraction=0.017) or former smokers (pinteraction=0.064) when compared with never smokers and among asthmatics compared with non-asthmatics (pinteraction=0.053). No significant interactions were observed between any GRS and house dust endotoxin. CONCLUSIONS: Evaluation of interactions using GRSs supports a greater impact of increased genetic susceptibility on reduced pulmonary function in the presence of smoking or asthma.


Asunto(s)
Asma , Estudio de Asociación del Genoma Completo , Adulto , Asma/genética , Estudios de Casos y Controles , Endotoxinas/toxicidad , Predisposición Genética a la Enfermedad , Humanos , Polimorfismo de Nucleótido Simple , Factores de Riesgo , Fumar/efectos adversos
3.
Am J Epidemiol ; 187(11): 2265-2278, 2018 11 01.
Artículo en Inglés | MEDLINE | ID: mdl-29982273

RESUMEN

Chronic lower respiratory diseases (CLRDs) are the fourth leading cause of death in the United States. To support investigations into CLRD risk determinants and new approaches to primary prevention, we aimed to harmonize and pool respiratory data from US general population-based cohorts. Data were obtained from prospective cohorts that performed prebronchodilator spirometry and were harmonized following 2005 ATS/ERS standards. In cohorts conducting follow-up for noncardiovascular events, CLRD events were defined as hospitalizations/deaths adjudicated as CLRD-related or assigned relevant administrative codes. Coding and variable names were applied uniformly. The pooled sample included 65,251 adults in 9 cohorts followed-up for CLRD-related mortality over 653,380 person-years during 1983-2016. Average baseline age was 52 years; 56% were female; 49% were never-smokers; and racial/ethnic composition was 44% white, 22% black, 28% Hispanic/Latino, and 5% American Indian. Over 96% had complete data on smoking, clinical CLRD diagnoses, and dyspnea. After excluding invalid spirometry examinations (13%), there were 105,696 valid examinations (median, 2 per participant). Of 29,351 participants followed for CLRD hospitalizations, median follow-up was 14 years; only 5% were lost to follow-up at 10 years. The NHLBI Pooled Cohorts Study provides a harmonization standard applied to a large, US population-based sample that may be used to advance epidemiologic research on CLRD.


Asunto(s)
Enfermedades Pulmonares Obstructivas/epidemiología , Enfermedades Pulmonares Obstructivas/fisiopatología , National Heart, Lung, and Blood Institute (U.S.)/organización & administración , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Pesos y Medidas Corporales , Bronquiectasia/epidemiología , Bronquiectasia/fisiopatología , Enfermedad Crónica , Estudios de Cohortes , Etnicidad/estadística & datos numéricos , Femenino , Hispánicos o Latinos/estadística & datos numéricos , Hospitalización/estadística & datos numéricos , Humanos , Indígenas Norteamericanos/estadística & datos numéricos , Exposición por Inhalación/estadística & datos numéricos , Enfermedades Pulmonares Obstructivas/etnología , Enfermedades Pulmonares Obstructivas/mortalidad , Masculino , Persona de Mediana Edad , National Heart, Lung, and Blood Institute (U.S.)/normas , Fenotipo , Grupos Raciales/estadística & datos numéricos , Pruebas de Función Respiratoria , Factores de Riesgo , Fumar/epidemiología , Factores Socioeconómicos , Estados Unidos/epidemiología , Población Blanca/estadística & datos numéricos , Adulto Joven
4.
Thorax ; 73(3): 279-282, 2018 03.
Artículo en Inglés | MEDLINE | ID: mdl-28689172

RESUMEN

Literature suggests that early exposure to the farming environment protects against atopy and asthma; few studies have examined pulmonary function. We evaluated associations between early-life farming exposures and pulmonary function in 3061 adults (mean age=63) from a US farming population using linear regression. Childhood raw milk consumption was associated with higher FEV1 (ß=49.5 mL, 95% CI 2.8 to 96.1 mL, p=0.04) and FVC (ß=66.2 mL, 95% CI 13.2 to 119.1 mL, p=0.01). We did not find appreciable associations with other early-life farming exposures. We report a novel association between raw milk consumption and higher pulmonary function that lasts into older adulthood.


Asunto(s)
Exposición a Riesgos Ambientales , Pulmón/fisiopatología , Leche/fisiología , Espirometría/métodos , Adulto , Anciano , Agricultura , Animales , Estudios de Casos y Controles , Niño , Preescolar , Granjas/estadística & datos numéricos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Fenómenos Fisiológicos Respiratorios , Estados Unidos
5.
Am J Respir Crit Care Med ; 196(8): 993-1003, 2017 10 15.
Artículo en Inglés | MEDLINE | ID: mdl-28613924

RESUMEN

RATIONALE: Accurate reference values for spirometry are important because the results are used for diagnosing common chronic lung diseases such as asthma and chronic obstructive pulmonary disease, estimating physiologic impairment, and predicting all-cause mortality. Reference equations have been established for Mexican Americans but not for others with Hispanic/Latino backgrounds. OBJECTIVES: To develop spirometry reference equations for adult Hispanic/Latino background groups in the United States. METHODS: The HCHS/SOL (Hispanic Community Health Study/Study of Latinos) recruited a population-based probability sample of 16,415 Hispanics/Latinos aged 18-74 years living in the Bronx, Chicago, Miami, and San Diego. Participants self-identified as being of Puerto Rican, Cuban, Dominican, Mexican, or Central or South American background. Spirometry was performed using standardized methods with central quality control monitoring. Spirometric measures from a subset of 6,425 never-smoking participants without respiratory symptoms or disease were modeled as a function of sex, age, height, and Hispanic/Latino background to produce background-specific reference equations for the predicted value and lower limit of normal. MEASUREMENTS AND MAIN RESULTS: Dominican and Puerto Rican Americans had substantially lower predicted and lower limit of normal values for FVC and FEV1 than those in other Hispanic/Latino background groups and also than Mexican American values from NHANES III (Third National Health and Nutrition Examination Survey). CONCLUSIONS: For patients of Dominican and Puerto Rican background who present with pulmonary symptoms in clinical practice, use of background-specific spirometry reference equations may provide more appropriate predicted and lower limit of normal values, enabling more accurate diagnoses of abnormality and physiologic impairment.


Asunto(s)
Emigrantes e Inmigrantes , Enfermedades Pulmonares/diagnóstico , Enfermedades Pulmonares/etnología , Estándares de Referencia , Adolescente , Adulto , Anciano , América Central , Femenino , Hispánicos o Latinos , Humanos , Masculino , Americanos Mexicanos , México , Persona de Mediana Edad , América del Sur , Espirometría , Estados Unidos/etnología , Adulto Joven
6.
Am J Respir Crit Care Med ; 196(11): 1463-1472, 2017 12 01.
Artículo en Inglés | MEDLINE | ID: mdl-29192835

RESUMEN

BACKGROUND: The American Thoracic Society committee on Proficiency Standards for Pulmonary Function Laboratories has recognized the need for a standardized reporting format for pulmonary function tests. Although prior documents have offered guidance on the reporting of test data, there is considerable variability in how these results are presented to end users, leading to potential confusion and miscommunication. METHODS: A project task force, consisting of the committee as a whole, was approved to develop a new Technical Standard on reporting pulmonary function test results. Three working groups addressed the presentation format, the reference data supporting interpretation of results, and a system for grading quality of test efforts. Each group reviewed relevant literature and wrote drafts that were merged into the final document. RESULTS: This document presents a reporting format in test-specific units for spirometry, lung volumes, and diffusing capacity that can be assembled into a report appropriate for a laboratory's practice. Recommended reference sources are updated with data for spirometry and diffusing capacity published since prior documents. A grading system is presented to encourage uniformity in the important function of test quality assessment. CONCLUSIONS: The committee believes that wide adoption of these formats and their underlying principles by equipment manufacturers and pulmonary function laboratories can improve the interpretation, communication, and understanding of test results.


Asunto(s)
Pulmón/fisiopatología , Proyectos de Investigación/normas , Pruebas de Función Respiratoria/normas , Comités Consultivos , Humanos , Sociedades Médicas , Estados Unidos
8.
Eur Respir J ; 48(1): 133-41, 2016 07.
Artículo en Inglés | MEDLINE | ID: mdl-27288032

RESUMEN

The diagnosis and severity categorisation of obstructive lung disease is determined using reference values. The American Thoracic Society/European Respiratory Society in 2005 recommended the National Health and Nutrition Examination Survey (NHANES) III spirometry prediction equations for patients in USA aged 8-80 years. The Global Lung Initiative 2012 (GLI 12) provided spirometry prediction equations for patients aged 3-95 years. Comparison of the NHANES III and GLI 12 prediction equations for diagnosing and categorising airway obstruction in patients in USA has not been made.We aimed to quantify the differences between NHANES III and GLI 12 predicted values in Caucasians aged 18-95 years, using both mathematical simulation and clinical data. We compared predicted forced expiratory volume in 1 s (FEV1) and lower limit of normal (LLN) FEV1/forced vital capacity (FVC) % for NHANES III and GLI 12 prediction equations by applying both a simulation model and clinical spirometry data to quantify differences in the diagnosis and categorisation of airway obstruction.Mathematical simulation revealed significant similarities and differences between prediction equations for both LLN FEV1/FVC % and predicted FEV1 There are significant differences when using GLI 12 and NHANES III to diagnose airway obstruction and severity in Caucasian patients aged 18-95 years.Similarities and differences exist between NHANES III and GLI 12 for some age and height combinations. The differences in LLN FEV1/FVC % and predicted FEV1 are most prominent in older taller/shorter individuals. The magnitude of the differences can be large and may result in differences in clinical management.


Asunto(s)
Enfermedades Pulmonares Obstructivas/clasificación , Enfermedades Pulmonares Obstructivas/diagnóstico , Pulmón/fisiopatología , Encuestas Nutricionales , Espirometría , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Europa (Continente) , Femenino , Volumen Espiratorio Forzado , Humanos , Masculino , Persona de Mediana Edad , Valores de Referencia , Índice de Severidad de la Enfermedad , Volumen de Ventilación Pulmonar , Estados Unidos , Población Blanca , Adulto Joven
9.
Eur Respir J ; 45(5): 1283-92, 2015 May.
Artículo en Inglés | MEDLINE | ID: mdl-25537554

RESUMEN

The 2005 American Thoracic Society (ATS)/European Respiratory Society (ERS) spirometry guidelines define valid tests as having three acceptable blows and a repeatable forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1). The aim of this study was to determine how reviewer and computer-determined ATS/ERS quality could affect population reference values for FVC and FEV1. Spirometry results from 7777 normal subjects aged 8-80 years (NHANES (National Health and Nutrition Examination Survey) III) were assigned quality grades A to F for FVC and FEV1 by a computer and one reviewer (reviewer 1). Results from a subgroup of 1466 Caucasian adults (aged 19-80 years ) were reviewed by two additional reviewers. Mean deviations from NHANES III predicted for FVC and FEV1 were examined by quality grade (A to F). Reviewer 1 rejected (D and F grade) 5.2% of the 7777 test sessions and the computer rejected ∼16%, primarily due to end-of-test (EOT) failures. Within the subgroup, the computer rejected 11.5% of the results and the three reviewers rejected 3.7-5.9%. Average FEV1 and FVC were minimally influenced by grades A to C allocated by reviewer 1. Quality assessment of individual blows including EOT assessments should primarily be used as an aid to good quality during testing rather than for subsequently disregarding data. Reconsideration of EOT criteria and its application, and improved grading standards and training in over-reading are required. Present EOT criteria results in the exclusion of too many subjects while having minimal impact on predicted values.


Asunto(s)
Diagnóstico por Computador , Volumen Espiratorio Forzado , Neumología/normas , Espirometría/métodos , Capacidad Vital , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Algoritmos , Niño , Bases de Datos Factuales , Femenino , Humanos , Masculino , Persona de Mediana Edad , Guías de Práctica Clínica como Asunto , Control de Calidad , Valores de Referencia , Proyectos de Investigación , Adulto Joven
10.
Eur Respir J ; 45(4): 1046-54, 2015 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-25395033

RESUMEN

The American Thoracic Society (ATS) and European Respiratory Society (ERS) recommend that spirometry prediction equations be derived from samples of similar race/ethnicity. Malagasy prediction equations do not exist. The objectives of this study were to establish prediction equations for healthy Malagasy adults, and then compare Malagasy measurements with published prediction equations. We enrolled 2491 healthy Malagasy subjects aged 18-73 years (1428 males) from June 2006 to April 2008. The subjects attempted to meet the ATS/ERS 2005 guidelines when performing forced expiratory spirograms. We compared Malagasy measurements of forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and FEV1/FVC with predictions from the European Community for Steel and Coal (ECSC), the third National Health and Nutrition Examination Survey (NHANES III) and the ERS Global Lung Function Initiative (GLI) 2012 study. A linear model for the entire population, using age and height as independent variables, best predicted all spirometry parameters for sea level and highland subjects. FEV1, FVC and FEV1/FVC were most accurately predicted by NHANES III African-American male and female, and by GLI 2012 black male and black and South East Asian female equations. ECSC-predicted FEV1, FVC and FEV1/FVC were poorly matched to Malagasy measurements. We provide the first spirometry reference equations for a healthy adult Malagasy population, and the first comparison of Malagasy population measurements with ECSC, NHANES III and GLI 2012 prediction equations.


Asunto(s)
Envejecimiento/fisiología , Volumen Espiratorio Forzado/fisiología , Mecánica Respiratoria/fisiología , Espirometría/métodos , Adolescente , Adulto , Negro o Afroamericano/estadística & datos numéricos , Factores de Edad , Anciano , Antropometría , Estudios de Cohortes , Países en Desarrollo , Femenino , Voluntarios Sanos , Humanos , Modelos Lineales , Madagascar , Masculino , Persona de Mediana Edad , Análisis Multivariante , Valor Predictivo de las Pruebas , Factores Sexuales , Población Blanca/estadística & datos numéricos , Adulto Joven
11.
Am J Respir Crit Care Med ; 189(8): 983-93, 2014 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-24735032

RESUMEN

PURPOSE: This document addresses aspects of the performance and interpretation of spirometry that are particularly important in the workplace, where inhalation exposures can affect lung function and cause or exacerbate lung diseases, such as asthma, chronic obstructive pulmonary disease, or fibrosis. METHODS: Issues that previous American Thoracic Society spirometry statements did not adequately address with respect to the workplace were identified for systematic review. Medline 1950-2012 and Embase 1980-2012 were searched for evidence related to the following: training for spirometry technicians; testing posture; appropriate reference values to use for Asians in North America; and interpretative strategies for analyzing longitudinal change in lung function. The evidence was reviewed and technical recommendations were developed. RESULTS: Spirometry performed in the work setting should be part of a comprehensive workplace respiratory health program. Effective technician training and feedback can improve the quality of spirometry testing. Posture-related changes in FEV1 and FVC, although small, may impact interpretation, so testing posture should be kept consistent and documented on repeat testing. Until North American Asian-specific equations are developed, applying a correction factor of 0.88 to white reference values is considered reasonable when testing Asian American individuals in North America. Current spirometry should be compared with previous tests. Excessive loss in FEV1 over time should be evaluated using either a percentage decline (15% plus loss expected due to aging) or one of the other approaches discussed, taking into consideration testing variability, worker exposures, symptoms, and other clinical information. CONCLUSIONS: Important aspects of workplace spirometry are discussed and recommendations are provided for the performance and interpretation of workplace spirometry.


Asunto(s)
Enfermedades Pulmonares/diagnóstico , Enfermedades Pulmonares/etiología , Enfermedades Profesionales/diagnóstico , Enfermedades Profesionales/etiología , Exposición Profesional/efectos adversos , Medicina del Trabajo/normas , Espirometría/normas , Asma/diagnóstico , Asma/etiología , Medicina Basada en la Evidencia , Volumen Espiratorio Forzado , Humanos , Vigilancia de la Población , Postura , Enfermedad Pulmonar Obstructiva Crónica/diagnóstico , Enfermedad Pulmonar Obstructiva Crónica/etiología , Fibrosis Pulmonar/diagnóstico , Fibrosis Pulmonar/etiología , Valores de Referencia , Estados Unidos
12.
Nano Lett ; 14(9): 5170-5, 2014 Sep 10.
Artículo en Inglés | MEDLINE | ID: mdl-25115623

RESUMEN

A purely planar graphene/SiC field effect transistor is presented here. The horizontal current flow over one-dimensional tunneling barrier between planar graphene contact and coplanar two-dimensional SiC channel exhibits superior on/off ratio compared to conventional transistors employing vertical electron transport. Multilayer epitaxial graphene (MEG) grown on SiC(0001̅) was adopted as the transistor source and drain. The channel is formed by the accumulation layer at the interface of semi-insulating SiC and a surface silicate that forms after high vacuum high temperature annealing. Electronic bands between the graphene edge and SiC accumulation layer form a thin Schottky barrier, which is dominated by tunneling at low temperatures. A thermionic emission prevails over tunneling at high temperatures. We show that neglecting tunneling effectively causes the temperature dependence of the Schottky barrier height. The channel can support current densities up to 35 A/m.

13.
Proc Natl Acad Sci U S A ; 108(41): 16900-5, 2011 Oct 11.
Artículo en Inglés | MEDLINE | ID: mdl-21960446

RESUMEN

After the pioneering investigations into graphene-based electronics at Georgia Tech, great strides have been made developing epitaxial graphene on silicon carbide (EG) as a new electronic material. EG has not only demonstrated its potential for large scale applications, it also has become an important material for fundamental two-dimensional electron gas physics. It was long known that graphene mono and multilayers grow on SiC crystals at high temperatures in ultrahigh vacuum. At these temperatures, silicon sublimes from the surface and the carbon rich surface layer transforms to graphene. However the quality of the graphene produced in ultrahigh vacuum is poor due to the high sublimation rates at relatively low temperatures. The Georgia Tech team developed growth methods involving encapsulating the SiC crystals in graphite enclosures, thereby sequestering the evaporated silicon and bringing growth process closer to equilibrium. In this confinement controlled sublimation (CCS) process, very high-quality graphene is grown on both polar faces of the SiC crystals. Since 2003, over 50 publications used CCS grown graphene, where it is known as the "furnace grown" graphene. Graphene multilayers grown on the carbon-terminated face of SiC, using the CCS method, were shown to consist of decoupled high mobility graphene layers. The CCS method is now applied on structured silicon carbide surfaces to produce high mobility nano-patterned graphene structures thereby demonstrating that EG is a viable contender for next-generation electronics. Here we present for the first time the CCS method that outperforms other epitaxial graphene production methods.

14.
COPD ; 11(4): 368-80, 2014 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-24568208

RESUMEN

INTRODUCTION: The contribution of occupational exposure to the risk of chronic obstructive pulmonary disease COPD in population-based studies is of interest. We compared the performance of self-reported exposure to a newly developed JEM in exposure-response evaluation. METHODS: We used cross-sectional data from Multi-Ethnic Study of Atherosclerosis (MESA), a population-based sample of 45-84 year olds free of clinical cardiovascular disease at baseline. MESA ascertained the most recent job and employment, and the MESA Lung Study measured spirometry, and occupational exposures for 3686 participants. Associations between health outcomes (spirometry defined airflow limitation and Medical Research Council-defined chronic bronchitis) and occupational exposure [self-reported occupational exposure to vapor-gas, dust, or fumes (VGDF), severity of exposure, and a job-exposure matrix (JEM)-derived score] were evaluated using logistic regression models adjusted for non-occupational risk factors. RESULTS: The prevalence of airflow limitation was associated with self-reported exposure to vapor-gas (OR 2.6, 95%CI 1.1-2.3), severity of VGDF exposure (P-trend < 0.01), and JEM dust exposure (OR 2.4, 95%CI 1.1-5.0), and with organic dust exposure in females; these associations were generally of greater magnitude among never smokers. The prevalence of chronic bronchitis and wheeze was associated with exposure to VGDF. The association between airflow limitation and the combined effect of smoking and VGDF exposure showed an increasing trend. Self-reported vapor-gas, dust, fumes, years and severity of exposure were associated with increased prevalence of chronic bronchitis and wheeze (P < 0.001). CONCLUSIONS: Airflow limitation was associated with self-reported VGDF exposure, its severity, and JEM-ascertained dust exposure in smokers and never-smokers in this multiethnic study.


Asunto(s)
Bronquitis Crónica/epidemiología , Polvo/análisis , Gases/análisis , Exposición Profesional/análisis , Enfermedad Pulmonar Obstructiva Crónica/epidemiología , Autoinforme , Anciano , Anciano de 80 o más Años , Aterosclerosis/epidemiología , Estudios Transversales , Etnicidad , Femenino , Volumen Espiratorio Forzado , Gases/toxicidad , Humanos , Masculino , Persona de Mediana Edad , Exposición Profesional/efectos adversos , Fenotipo , Prevalencia , Enfermedad Pulmonar Obstructiva Crónica/fisiopatología , Ruidos Respiratorios , Factores de Riesgo , Fumar , Espirometría , Estados Unidos/epidemiología , Capacidad Vital
15.
Nano Lett ; 13(3): 942-7, 2013 Mar 13.
Artículo en Inglés | MEDLINE | ID: mdl-23418924

RESUMEN

The maximum oscillation frequency (fmax) quantifies the practical upper bound for useful circuit operation. We report here an fmax of 70 GHz in transistors using epitaxial graphene grown on the C-face of SiC. This is a significant improvement over Si-face epitaxial graphene used in the prior high-frequency transistor studies, exemplifying the superior electronics potential of C-face epitaxial graphene. Careful transistor design using a high κ dielectric T-gate and self-aligned contacts further contributed to the record-breaking fmax.

16.
Eur Respir J ; 40(6): 1324-43, 2012 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-22743675

RESUMEN

The aim of the Task Force was to derive continuous prediction equations and their lower limits of normal for spirometric indices, which are applicable globally. Over 160,000 data points from 72 centres in 33 countries were shared with the European Respiratory Society Global Lung Function Initiative. Eliminating data that could not be used (mostly missing ethnic group, some outliers) left 97,759 records of healthy nonsmokers (55.3% females) aged 2.5-95 yrs. Lung function data were collated and prediction equations derived using the LMS method, which allows simultaneous modelling of the mean (mu), the coefficient of variation (sigma) and skewness (lambda) of a distribution family. After discarding 23,572 records, mostly because they could not be combined with other ethnic or geographic groups, reference equations were derived for healthy individuals aged 3-95 yrs for Caucasians (n=57,395), African-Americans (n=3,545), and North (n=4,992) and South East Asians (n=8,255). Forced expiratory value in 1 s (FEV(1)) and forced vital capacity (FVC) between ethnic groups differed proportionally from that in Caucasians, such that FEV(1)/FVC remained virtually independent of ethnic group. For individuals not represented by these four groups, or of mixed ethnic origins, a composite equation taken as the average of the above equations is provided to facilitate interpretation until a more appropriate solution is developed. Spirometric prediction equations for the 3-95-age range are now available that include appropriate age-dependent lower limits of normal. They can be applied globally to different ethnic groups. Additional data from the Indian subcontinent and Arabic, Polynesian and Latin American countries, as well as Africa will further improve these equations in the future.


Asunto(s)
Neumología/normas , Espirometría/métodos , Espirometría/normas , Adolescente , Adulto , Factores de Edad , Anciano , Anciano de 80 o más Años , Niño , Preescolar , Etnicidad , Femenino , Volumen Espiratorio Forzado , Salud Global , Humanos , Pulmón/fisiología , Masculino , Persona de Mediana Edad , Modelos Estadísticos , Neumología/métodos , Control de Calidad , Valores de Referencia , Capacidad Vital
17.
Environ Health Perspect ; 130(8): 87008, 2022 08.
Artículo en Inglés | MEDLINE | ID: mdl-36006053

RESUMEN

BACKGROUND: In low- and middle-income countries, burning biomass indoors for cooking or heating has been associated with poorer lung function. In high-income countries, wood, a form of biomass, is commonly used for heating in rural areas with increasing prevalence. However, in these settings the potential impact of chronic indoor woodsmoke exposure on pulmonary function is little studied. OBJECTIVE: We evaluated the association of residential wood burning with pulmonary function in case-control study of asthma nested within a U.S. rural cohort. METHODS: Using sample weighted multivariable linear regression, we estimated associations between some and frequent wood burning, both relative to no exposure, in relation to forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), their ratio (FEV1/FVC), and fractional exhaled nitric oxide (FeNO). We examined effect modification by smoking or asthma status. RESULTS: Among all participants and within smoking groups, wood burning was not appreciably related to pulmonary function. However, in individuals with asthma (n=1,083), frequent wood burning was significantly associated with lower FEV1 [ß: -164mL; 95% confidence interval (CI): -261, -66mL], FVC (ß: -125mL; 95% CI: -230, -20mL), and FEV1/FVC (ß: -2%; 95% CI: -4, -0.4%), whereas no appreciable association was seen in individuals without asthma (n=1,732). These differences in association by asthma were statistically significant for FEV1 (pinteraction=0.0044) and FEV1/FVC (pinteraction=0.049). Frequent wood burning was also associated with higher FeNO levels in all individuals (n=2,598; ß: 0.1 ln(ppb); 95% CI: 0.02, 0.2), but associations did not differ by asthma or smoking status. DISCUSSION: Frequent exposure to residential wood burning was associated with a measure of airway inflammation (FeNO) among all individuals and with lower pulmonary function among individuals with asthma. This group may wish to reduce wood burning or consider using air filtration devices. https://doi.org/10.1289/EHP10734.


Asunto(s)
Asma , Madera , Asma/epidemiología , Volumen Espiratorio Forzado , Humanos , Pulmón , Capacidad Vital
18.
Am J Epidemiol ; 173(4): 376-87, 2011 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-21242304

RESUMEN

Current guidelines recommend separate spirometry reference equations for whites, African Americans, and Mexican Americans, but the justification for this recommendation is controversial. The authors examined the statistical justification for race/ethnic-specific reference equations in adults in the Third National Health and Nutrition Examination Survey (1988-1994) and the Multi-Ethnic Study of Atherosclerosis Lung Study (2000-2006). Spirometry was measured following American Thoracic Society guidelines. "Statistical justification" was defined as the presence of effect modification by race/ethnicity among never-smoking participants without respiratory disease or symptoms and was tested with interaction terms for race/ethnicity (× age and height) in regression models. There was no evidence of effect modification by race/ethnicity for forced expiratory volume in 1 second, forced vital capacity, or the forced expiratory volume in 1 second/forced vital capacity ratio among white, African-American, and Mexican-American men or women on an additive scale or a log scale. Interaction terms for race/ethnicity explained less than 1% of variability in lung function. The mean lung function for a given age, gender, and height was the same for whites and Mexican Americans but was lower for African Americans. Findings were similar in the Multi-Ethnic Study of Atherosclerosis Lung Study. The associations of age and height with lung function are similar across the 3 major US race/ethnic groups. Multiethnic rather than race/ethnic-specific spirometry reference equations are applicable for the US population.


Asunto(s)
Negro o Afroamericano/estadística & datos numéricos , Estatura , Hispánicos o Latinos/estadística & datos numéricos , Fenómenos Fisiológicos Respiratorios , Población Blanca/estadística & datos numéricos , Adulto , Factores de Edad , Anciano , Anciano de 80 o más Años , Enfermedades Cardiovasculares/epidemiología , Enfermedades Cardiovasculares/etnología , Enfermedades Cardiovasculares/fisiopatología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Encuestas Nutricionales , Guías de Práctica Clínica como Asunto , Valor Predictivo de las Pruebas , Estudios Prospectivos , Análisis de Regresión , Pruebas de Función Respiratoria , Estados Unidos/epidemiología
19.
Langmuir ; 27(3): 863-5, 2011 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-21182241

RESUMEN

Graphene's extraordinary physical properties and its planar geometry make it an ideal candidate for a wide array of applications, many of which require controlled chemical modification and the spatial organization of molecules on its surface. In particular, the ability to functionalize and micropattern graphene with proteins is relevant to bioscience applications such as biomolecular sensors, single-cell sensors, and tissue engineering. We report a general strategy for the noncovalent chemical modification of epitaxial graphene for protein immobilization and micropatterning. We show that bifunctional molecule pyrenebutanoic acid-succinimidyl ester (PYR-NHS), composed of the hydrophobic pyrene and the reactive succinimide ester group, binds to graphene noncovalently but irreversibly. We investigate whether the chemical treatment perturbs the electronic band structure of graphene using X-ray photoemission (XPS) and Raman spectroscopy. Our results show that the sp(2) hybridization remains intact and that the π band maintains its characteristic Lorentzian shape in the Raman spectra. The modified graphene surfaces, which bind specifically to amines in proteins, are micropatterned with arrays of fluorescently labeled proteins that are relevant to glucose sensors (glucose oxidase) and cell sensor and tissue engineering applications (laminin).


Asunto(s)
Grafito/química , Nanotecnología/métodos , Proteínas/química , Espectrometría Raman
20.
J Am Coll Nutr ; 29(5): 494-502, 2010 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-21504976

RESUMEN

OBJECTIVE: Dairy products contain vitamin D and other nutrients that may be beneficial for lung function, but they are also high in fats that may have mixed effects on lung function. However, the overall associations of dairy intake with lung density and lung function have not been studied. METHODS: We examined the cross-sectional relationships between dairy intake and computed tomography (CT) lung density and lung function in the Multi-Ethnic Study of Atherosclerosis (MESA). Total, low-fat, and high-fat dairy intakes were quantified from food frequency questionnaire responses of men and women who were ages 45-84 years and free of clinical cardiovascular disease. The MESA-Lung Study assessed CT lung density from cardiac CT imaging and prebronchodilator spirometry among 3965 MESA participants. RESULTS: Total dairy intake was inversely associated with apical-basilar difference in percent emphysema and positively associated with forced vital capacity (FVC) (the multivariate-adjusted mean difference between the highest and lowest quintiles of total dairy intake was -0.92 [p for trend = 0.04] for apical-basilar difference in percent emphysema and 72.0 mL [p = 0.01] for FVC). Greater low-fat dairy intake was associated with higher alpha (higher alpha values indicate less emphysema) and lower apical-basilar difference in percent emphysema (corresponding differences in alpha and apical-basilar difference in percent emphysema were 0.04 [p = 0.02] and -0.98 [p = 0.01] for low-fat dairy intake, respectively). High-fat dairy intake was not associated with lung density measures. Greater low- or high-fat dairy intake was not associated with higher forced expiratory volume in 1 second (FEV(1)), FVC, and FEV(1)/FVC. CONCLUSIONS: Higher low-fat dairy intake but not high-fat dairy intake was associated with moderately improved CT lung density.


Asunto(s)
Productos Lácteos , Grasas de la Dieta/farmacología , Enfisema/prevención & control , Enfermedades Pulmonares/prevención & control , Pulmón/fisiopatología , Capacidad Vital/efectos de los fármacos , Anciano , Anciano de 80 o más Años , Broncoespirometría , Estudios Transversales , Femenino , Humanos , Pulmón/diagnóstico por imagen , Pulmón/patología , Enfermedades Pulmonares/patología , Enfermedades Pulmonares/fisiopatología , Masculino , Persona de Mediana Edad , Encuestas y Cuestionarios , Tomografía Computarizada por Rayos X
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