Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 69
Filtrar
Más filtros

Banco de datos
País/Región como asunto
Tipo del documento
Intervalo de año de publicación
1.
J Child Psychol Psychiatry ; 65(5): 656-667, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-37469104

RESUMEN

BACKGROUND: How best to improve the early detection of autism spectrum disorder (ASD) is the subject of significant controversy. Some argue that universal ASD screeners are highly accurate, whereas others argue that evidence for this claim is insufficient. Relatedly, there is no clear consensus as to the optimal role of screening for making referral decisions for evaluation and treatment. Published screening research can meaningfully inform these questions-but only through careful consideration of children who do not complete diagnostic follow-up. METHODS: We developed two simulation models that re-analyze the results of a large-scale validation study of the M-CHAT-R/F by Robins et al. (2014, Pediatrics, 133, 37). Model #1 re-analyzes screener accuracy across six scenarios, each reflecting different assumptions regarding loss to follow-up. Model #2 builds on this by closely examining differential attrition at each point of the multi-step detection process. RESULTS: Estimates of sensitivity ranged from 40% to 94% across scenarios, demonstrating that estimates of accuracy depend on assumptions regarding the diagnostic status of children who were lost to follow-up. Across a range of plausible assumptions, data also suggest that children with undiagnosed ASD may be more likely to complete follow-up than children without ASD, highlighting the role of clinicians and caregivers in the detection process. CONCLUSIONS: Using simulation modeling as a quantitative method to examine potential bias in screening studies, analyses suggest that ASD screening tools may be less accurate than is often reported. Models also demonstrate the critical importance of every step in a detection process-including steps that determine whether children should complete an additional evaluation. We conclude that parent and clinician decision-making regarding follow-up may contribute more to detection than is widely assumed.


Asunto(s)
Trastorno del Espectro Autista , Trastorno Autístico , Humanos , Niño , Trastorno Autístico/diagnóstico , Trastorno del Espectro Autista/diagnóstico , Estudios de Seguimiento , Diagnóstico Precoz , Tamizaje Masivo
2.
J Biopharm Stat ; 32(1): 90-106, 2022 01 02.
Artículo en Inglés | MEDLINE | ID: mdl-34632951

RESUMEN

In current clinical trial development, historical information is receiving more attention as it provides utility beyond sample size calculation. Meta-analytic-predictive (MAP) priors and robust MAP priors have been proposed for prospectively borrowing historical data on a single endpoint. To simultaneously synthesize control information from multiple endpoints in confirmatory clinical trials, we propose to approximate posterior probabilities from a Bayesian hierarchical model and estimate critical values by deep learning to construct pre-specified strategies for hypothesis testing. This feature is important to ensure study integrity by establishing prospective decision functions before the trial conduct. Simulations are performed to show that our method properly controls family-wise error rate and preserves power as compared with a typical practice of choosing constant critical values given a subset of null space. Satisfactory performance under prior-data conflict is also demonstrated. We further illustrate our method using a case study in Immunology.


Asunto(s)
Proyectos de Investigación , Teorema de Bayes , Simulación por Computador , Humanos , Probabilidad , Tamaño de la Muestra
3.
Exp Eye Res ; 205: 108498, 2021 04.
Artículo en Inglés | MEDLINE | ID: mdl-33600810

RESUMEN

Diffusion is an important mechanism of transport for nutrients and drugs throughout the avascular corneal stroma. The purpose of this study was to investigate the depth- and direction-dependent changes in stromal transport properties and their relationship to changes in collagen structure following ultraviolet A (UVA)-riboflavin induced corneal collagen cross-linking (CXL). After cross-linking in ex vivo porcine eyes, fluorescence recovery after photobleaching (FRAP) was performed to measure fluorescein diffusion in the nasal-temporal (NT) and anterior-posterior (AP) directions at corneal depths of 100, 200, and 300 µm. Second harmonic generation (SHG) imaging was also performed at these three corneal depths to quantify fiber alignment. For additional confirmation, an electrical conductivity method was employed to quantify ion permeability in the AP direction in corneal buttons and immunohistochemistry (IHC) was used to image collagen structure. Cross-linked corneas were compared to a control treatment that received the riboflavin solution without UVA light (SHAM). The results of FRAP revealed that fluorescein diffusivity decreased from 23.39 ± 11.60 µm2/s in the SHAM group to 19.87 ± 10.10 µm2/s in the CXL group. This change was dependent on depth and direction: the decrease was more pronounced in the 100 µm depth (P = 0.0005) and AP direction (P = 0.001) when compared to the effect in deeper locations and in the NT direction, respectively. Conductivity experiments confirmed a decrease in solute transport in the AP direction (P < 0.0001). FRAP also detected diffusional anisotropy in the porcine cornea: the fluorescein diffusivity in the NT direction was higher than the diffusivity in the AP direction. This anisotropy was increased following CXL treatment. Both SHG and IHC revealed a qualitative decrease in collagen crimping following CXL. Analysis of SHG images revealed an increase in coherency in the anterior 200 µm of CXL treated corneas when compared to SHAM treated corneas (P < 0.01). In conclusion, CXL results in a decrease in stromal solute transport, and this decrease is concentrated in the most anterior region and AP direction. Solute transport in the porcine cornea is anisotropic, and an increase in anisotropy with CXL may be explained by a decrease in collagen crimping.


Asunto(s)
Sustancia Propia/efectos de los fármacos , Reactivos de Enlaces Cruzados , Fluoresceína/metabolismo , Fármacos Fotosensibilizantes/farmacología , Riboflavina/farmacología , Animales , Transporte Biológico Activo/fisiología , Colágeno Tipo I/metabolismo , Sustancia Propia/metabolismo , Conductividad Eléctrica , Inmunohistoquímica , Transporte Iónico/fisiología , Masculino , Fotoquimioterapia , Sus scrofa , Rayos Ultravioleta
4.
Public Health Nurs ; 37(1): 16-24, 2020 01.
Artículo en Inglés | MEDLINE | ID: mdl-31489717

RESUMEN

OBJECTIVE: Diabetes is a major health problem that is closely linked with cardiovascular disease (CVD), the leading cause of death in the United States. The purpose of this analysis was to determine the effect of a culturally relevant diabetes health promotion program on diabetes knowledge and self-reported self-care behaviors. DESIGN: A cluster randomized controlled trial was conducted in 12 rural church settings. Seven churches were randomized to the intervention group and five to the control group. SAMPLE: The sample included 146 African American participants diagnosed with diabetes and prediabetes. INTERVENTION: The intervention group participants (n = 75) received the diabetes health program, and those in the control group (n = 71) group received a publicly available diabetes health brochure. MEASURES: Data were collected about diabetes knowledge, self-care activities, fatalism, and social support. RESULTS: Linear mixed model was the statistical test used to analyze group differences. Compared with the control group, the intervention group showed significant changes from pretest to posttest for diabetes knowledge and behaviors associated with diet and blood glucose testing. CONCLUSION: Health promotion programs implemented by public health nurses among rural groups at increased risk for developing CVD can facilitate understanding about strategies to reduce disease risk.


Asunto(s)
Enfermedades Cardiovasculares/epidemiología , Diabetes Mellitus/epidemiología , Promoción de la Salud/métodos , Estado Prediabético/epidemiología , Población Rural/estadística & datos numéricos , Adulto , Negro o Afroamericano/psicología , Negro o Afroamericano/estadística & datos numéricos , Anciano , Análisis por Conglomerados , Dieta , Femenino , Conocimientos, Actitudes y Práctica en Salud , Humanos , Masculino , Persona de Mediana Edad , Autocuidado , Apoyo Social , Estados Unidos/epidemiología
5.
Health Educ Res ; 34(2): 200-208, 2019 04 01.
Artículo en Inglés | MEDLINE | ID: mdl-30601979

RESUMEN

Cardiovascular disease (CVD) is a major cause of death among people living in the United States. Populations, especially minorities, living in the rural South are disproportionately affected by CVD and have greater CVD risk, morbidity and mortality. Culturally relevant cardiovascular health programs implemented in rural community settings can potentially reduce CVD risk and facilitate health behavior modification. The purpose of this study was to examine the effects of a cardiovascular health promotion intervention on the health habits of a group of rural African American adults. The study had a cluster randomized controlled trial design involving 12 rural churches that served as statistical clusters. From the churches (n = 6) randomized to the intervention group, 115 participants were enrolled, received the 6-week health program and completed pretest-posttest measures. The 114 participants from the control group churches (n = 6) did not receive the health program and completed the same pretest-posttest measures. The linear mixed model was used to compare group differences from pretest to posttest. The educational health intervention positively influenced select dietary and confidence factors that may contribute toward CVD risk reduction.


Asunto(s)
Negro o Afroamericano , Enfermedades Cardiovasculares/etnología , Organizaciones Religiosas/organización & administración , Conductas Relacionadas con la Salud , Promoción de la Salud/organización & administración , Adulto , Anciano , Terapia Conductista/métodos , Enfermedades Cardiovasculares/prevención & control , Dieta , Femenino , Humanos , Masculino , Persona de Mediana Edad , Población Rural , Estados Unidos
6.
J Oral Maxillofac Surg ; 77(11): 2245-2257, 2019 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-31125537

RESUMEN

PURPOSE: Approximately 2 to 4% of the US population have been estimated to seek treatment for temporomandibular symptoms, predominately women. The study purpose was to determine whether sex-specific differences in temporomandibular morphometry result from scaling with sex differences in skull size and shape or intrinsic sex-specific differences. MATERIALS AND METHODS: A total of 22 (11 male [aged 74.5 ± 9.1 years]; 11 female [aged 73.6 ± 12.8 years]) human cadaveric heads with no history of temporomandibular disc derangement underwent cone beam computed tomography and high-resolution magnetic resonance imaging scanning to determine 3-dimensional cephalometric parameters and temporomandibular morphometric outcomes. Regression models between morphometric outcomes and cephalometric parameters were developed, and intrinsic sex-specific differences in temporomandibular morphometry normalized by cephalometric parameters were determined. Subject-specific finite element (FE) models of the extreme male and extreme female conditions were developed to predict variations in articular disc stress-strain under the same joint loading. RESULTS: In some cases, sex differences in temporomandibular morphometric parameters could be explained by linear scaling with skull size and shape; however, scaling alone could not fully account for some differences between sexes, indicating intrinsic sex-specific differences. The intrinsic sex-specific differences in temporomandibular morphometry included an increased condylar medial length and mediolateral disc lengths in men and a longer anteroposterior disc length in women. Considering the extreme male and female temporomandibular morphometry observed in the present study, subject-specific FE models resulted in sex differences, with the extreme male joint having a broadly distributed stress field and peak stress of 5.28 MPa. The extreme female joint had a concentrated stress field and peak stress of 7.37 MPa. CONCLUSIONS: Intrinsic sex-specific differences independent of scaling with donor skull size were identified in temporomandibular morphometry. Understanding intrinsic sex-specific morphometric differences is critical to determining the temporomandibular biomechanics given the effect of anatomy on joint contact mechanics and stress-strain distributions and requires further study as one potential factor for the increased predisposition of women to temporomandibular disc derangement.


Asunto(s)
Luxaciones Articulares , Disco de la Articulación Temporomandibular , Articulación Temporomandibular , Anciano , Anciano de 80 o más Años , Cadáver , Femenino , Humanos , Imagen por Resonancia Magnética , Masculino , Cóndilo Mandibular/anatomía & histología , Persona de Mediana Edad , Caracteres Sexuales , Cráneo , Articulación Temporomandibular/anatomía & histología , Disco de la Articulación Temporomandibular/anatomía & histología
7.
J Cardiovasc Nurs ; 33(1): E8-E14, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-28353542

RESUMEN

BACKGROUND: Cardiovascular disease is a major cause of death for people living in the United States. African Americans bear a disproportionate burden of cardiovascular disease. Interventions designed to target multiple risk factors may facilitate elimination of cardiovascular disease health disparities. OBJECTIVE: The purpose of this study was to evaluate a culturally relevant cardiovascular health promotion intervention that could potentially reduce cardiovascular disease risk among a group of rural African American adults by improving intentions, attitudes, norms, and self-efficacy to increase produce consumption, reduce dietary saturated fat intake, and increase exercise. METHODS: A cluster randomized controlled trial design was used to evaluate the effect of the "With Every Heartbeat Is Life" cardiovascular health promotion program among rural African Americans. The African American congregants of 12 rural churches located in northern Florida were randomly assigned to either an intervention group that received a culturally relevant cardiovascular health promotion intervention or a control group. Data analysis using linear mixed model was performed to compare group differences from pretest to posttest. RESULTS: The cardiovascular health promotion intervention had a positive influence on the intentions, attitudes, norms, and self-efficacy of rural African Americans to increase produce consumption and reduce dietary saturated fat. The intervention also enhanced participants' attitudes and self-efficacy regarding exercise. CONCLUSION: The culturally relevant cardiovascular health promotion program presented to cluster groups of rural African American participants had positive influences on psychosocial variables associated with engaging in cardiovascular health recommendations. Nurse-led interventions in community settings can potentially reduce cardiovascular disease risk.


Asunto(s)
Negro o Afroamericano , Enfermedades Cardiovasculares/etnología , Enfermedades Cardiovasculares/prevención & control , Educación en Salud , Promoción de la Salud , Adulto , Anciano , Dieta , Ejercicio Físico , Femenino , Florida , Conductas Relacionadas con la Salud , Humanos , Masculino , Persona de Mediana Edad , Salud Rural , Población Rural , Autoeficacia
8.
Comput Stat Data Anal ; 82: 152-163, 2015 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-25892835

RESUMEN

In medicine, it is often useful to stratify patients according to disease risk, severity, or response to therapy. Since many diseases arise from complex gene-gene and gene-environment interactions, patient strata may be defined by combinations of genetic and environmental factors. Traditional statistical methods require specifying interactions a priori making it difficult to identify high order interactions. Alternatively, machine learning methods can model complex interactions, however these models are often difficult to interpret in a clinical setting. Logic regression (LR) enables modeling a binary outcome using logical combinations of binary predictors yielding easily interpretable models. However LR, as currently available, cannot model ordinal responses. This paper extends LR to model an ordinal response and the resulting method is called Ordinal Logic Regression (OLR). Several simulations comparing OLR and Classification and Regression Trees (CART) demonstrate that OLR is superior to CART for identifying variable interactions associated with an ordinal response. OLR is applied to data from a study to determine associations between genetic and health factors with severity of adult periodontitis.

9.
J Biomech ; 169: 112131, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38739987

RESUMEN

Cartilage endplates (CEPs) act as protective mechanical barriers for intervertebral discs (IVDs), yet their heterogeneous structure-function relationships are poorly understood. This study addressed this gap by characterizing and correlating the regional biphasic mechanical properties and biochemical composition of human lumbar CEPs. Samples from central, lateral, anterior, and posterior portions of the disc (n = 8/region) were mechanically tested under confined compression to quantify swelling pressure, equilibrium aggregate modulus, and hydraulic permeability. These properties were correlated with CEP porosity and glycosaminoglycan (s-GAG) content, which were obtained by biochemical assays of the same specimens. Both swelling pressure (142.79 ± 85.89 kPa) and aggregate modulus (1864.10 ± 1240.99 kPa) were found to be regionally dependent (p = 0.0001 and p = 0.0067, respectively) in the CEP and trended lowest in the central location. No significant regional dependence was observed for CEP permeability (1.35 ± 0.97 * 10-16 m4/Ns). Porosity measurements correlated significantly with swelling pressure (r = -0.40, p = 0.0227), aggregate modulus (r = -0.49, p = 0.0046), and permeability (r = 0.36, p = 0.0421), and appeared to be the primary indicator of CEP biphasic mechanical properties. Second harmonic generation microscopy also revealed regional patterns of collagen fiber anchoring, with fibers inserting the CEP perpendicularly in the central region and at off-axial directions in peripheral regions. These results suggest that CEP tissue has regionally dependent mechanical properties which are likely due to the regional variation in porosity and matrix structure. This work advances our understanding of healthy baseline endplate biomechanics and lays a groundwork for further understanding the role of CEPs in IVD degeneration.


Asunto(s)
Disco Intervertebral , Vértebras Lumbares , Humanos , Vértebras Lumbares/fisiología , Disco Intervertebral/fisiología , Persona de Mediana Edad , Masculino , Femenino , Porosidad , Adulto , Anciano , Glicosaminoglicanos/metabolismo , Fenómenos Biomecánicos , Cartílago/fisiología , Estrés Mecánico
10.
Prostate ; 73(3): 328-35, 2013 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-22887343

RESUMEN

PURPOSE: This study was conducted to investigate the effect of Se supplementation on prostate cancer incidence in men at high risk for prostate cancer. METHODS: A Phase 3 randomized, double-blind, placebo-controlled clinical trial was conducted in 699 men at high risk for prostate cancer (prostate specific antigen (PSA) >4 ng/ml and/or suspicious digital rectal examination and/or PSA velocity >0.75 ng/ml/year), but with a negative prostate biopsy. Participants were randomized to receive daily oral placebo (N = 232), 200 µg selenium (N = 234), or 400 µg selenium (N = 233) as selenized yeast. They were followed every 6 months for up to 5 years. The time to diagnosis of prostate cancer was compared between treatment groups using the Cox proportional hazards model. RESULT: Compared to placebo, the hazard ratios [95% confidence intervals] for risk of developing prostate cancer in the selenium 200 µg/day or the selenium 400 µg/day group were 0.94 [0.52, 1.7] and 0.90 [0.48, 1.7], respectively. PSA velocity in the selenium arms was not significantly different from that observed in the placebo group (P = 0.18 and P = 0.17, respectively). CONCLUSION: Selenium supplementation appeared to have no effect on the incidence of prostate cancer in men at high risk. In conjunction with results of other studies, these data indicate that selenium supplementation may not have a role in prostate cancer chemoprevention.


Asunto(s)
Suplementos Dietéticos , Neoplasias de la Próstata/epidemiología , Selenio/administración & dosificación , Selenio/farmacología , Administración Oral , Anciano , Biopsia , Relación Dosis-Respuesta a Droga , Método Doble Ciego , Estudios de Seguimiento , Humanos , Incidencia , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Modelos de Riesgos Proporcionales , Antígeno Prostático Específico/sangre , Neoplasias de la Próstata/sangre , Neoplasias de la Próstata/patología , Factores de Riesgo , Selenio/efectos adversos
11.
Stat Med ; 32(15): 2629-42, 2013 Jul 10.
Artículo en Inglés | MEDLINE | ID: mdl-23280968

RESUMEN

For a heart transplant patient, the risk of graft rejection and risk of death are likely to be associated. Two fully specified Bayesian models for recurrent events with dependent termination are applied to investigate the potential relationships between these two types of risk as well as association with risk factors. We particularly focus on the choice of priors, selection of the appropriate prediction model, and prediction methods for these two types of risk for an individual patient. Our prediction tools can be easily implemented and helpful to physicians for setting heart transplant patients' biopsy schedule.


Asunto(s)
Teorema de Bayes , Bioestadística/métodos , Trasplante de Corazón/estadística & datos numéricos , Biopsia , Femenino , Rechazo de Injerto/diagnóstico , Rechazo de Injerto/etiología , Trasplante de Corazón/efectos adversos , Trasplante de Corazón/mortalidad , Humanos , Masculino , Modelos Estadísticos , Factores de Riesgo , Procesos Estocásticos
12.
J Clin Periodontol ; 40(8): 757-64, 2013 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-23742695

RESUMEN

AIM: Following toll-like receptor (TLR) engagement, lipopolysaccharide (LPS) can stimulate the expression of pro-inflammatory cytokines thus activating the innate immune response. The production of inflammatory cytokines results, in part, from the activation of kinase-induced signalling cascades and transcriptional factors. Of the four distinct classes of mitogen-activated protein kinases (MAPK) described in mammals, p38, c-Jun N-terminal activated kinases (JNK1-3) and extracellular activated kinases (ERK1,2) are the best studied. Previous data have established that p38 MAPK signalling is required for inflammation and bone loss in periodontal disease pre-clinical animal models. MATERIALS & METHODS: In this study, we obtained healthy and diseased periodontal tissues along with clinical parameters and microbiological parameters. Excised fixed tissues were immunostained with total and phospho-specific antibodies against p38, JNK and ERK kinases. RESULTS: Intensity scoring from immunostained tissues was correlated with clinical periodontal parameters. Rank correlations with clinical indices were statistically significantly positive (p-value < 0.05) for total p38 (correlations ranging 0.49-0.68), phospho-p38 (range 0.44-0.56), and total ERK (range 0.52-0.59) levels, and correlations with JNK levels also supported association (range 0.42-0.59). Phospho-JNK and phospho-ERK showed no significant positive correlation with clinical parameters of disease. CONCLUSION: These data strongly implicate p38 MAPK as a major MAPK involved in human periodontal inflammation and severity.


Asunto(s)
Periodontitis Crónica/enzimología , Proteínas Quinasas Activadas por Mitógenos/análisis , Bacteroides/aislamiento & purificación , Periodontitis Crónica/inmunología , Periodontitis Crónica/microbiología , Índice de Placa Dental , Femenino , Hemorragia Gingival/enzimología , Hemorragia Gingival/inmunología , Hemorragia Gingival/microbiología , Recesión Gingival/enzimología , Recesión Gingival/inmunología , Recesión Gingival/microbiología , Humanos , Linfocitos/inmunología , Macrófagos/inmunología , Masculino , Proteína Quinasa 1 Activada por Mitógenos/análisis , Proteína Quinasa 10 Activada por Mitógenos/análisis , Proteína Quinasa 3 Activada por Mitógenos/análisis , Proteína Quinasa 8 Activada por Mitógenos/análisis , Proteína Quinasa 9 Activada por Mitógenos/análisis , Pérdida de la Inserción Periodontal/enzimología , Pérdida de la Inserción Periodontal/inmunología , Pérdida de la Inserción Periodontal/microbiología , Índice Periodontal , Bolsa Periodontal/enzimología , Bolsa Periodontal/inmunología , Bolsa Periodontal/microbiología , Periodoncio/enzimología , Células Plasmáticas/inmunología , Porphyromonas gingivalis/aislamiento & purificación , Treponema denticola/aislamiento & purificación , Proteínas Quinasas p38 Activadas por Mitógenos/análisis
13.
J Clin Periodontol ; 40(6): 599-606, 2013 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-23557538

RESUMEN

AIM: To assess associations of metabolic syndrome, and its individual components, with extent of severe periodontitis among patients with type 2 diabetes mellitus (T2DM). MATERIALS & METHODS: We performed a secondary data analysis (N = 283) using a cross-sectional study population of Gullah African Americans with T2DM. Extent of severe periodontitis was assessed as total diseased tooth-sites/person [evaluated as separate outcomes: 6+mm clinical attachment level (CAL), 5+mm periodontal probing depth (PPD)] using negative binomial regression techniques. Primary independent variables assessed in separate models included metabolic syndrome (yes/no), each metabolic syndrome component (low HDL, hypertension, high triglycerides, large waist circumference) and glycemic control (poor/good). RESULTS: Multivariable CAL-model results showed a significant association for metabolic syndrome status with extent of severe periodontitis (RR = 2.77, p = 0.03). The separate multivariable CAL-model including each metabolic syndrome component showed marginally increased rates among those with large waist circumference (RR = 2.33, p = 0.09) and those with HbA1c ≥ 7% (RR = 1.73, p = 0.06). Multivariable PPD-models showed marginally increased rates among those with metabolic syndrome (RR = 2.18, p = 0.06). CONCLUSION: Metabolic syndrome is associated with the extent of severe periodontitis in this Gullah population with T2DM.


Asunto(s)
Negro o Afroamericano , Periodontitis Crónica/complicaciones , Diabetes Mellitus Tipo 2/complicaciones , Síndrome Metabólico/complicaciones , Síndrome Metabólico/etnología , Adulto , Anciano , Periodontitis Crónica/etnología , Estudios Transversales , Diabetes Mellitus Tipo 2/etnología , Femenino , Humanos , Hipertensión/complicaciones , Hipertrigliceridemia/complicaciones , Funciones de Verosimilitud , Masculino , Persona de Mediana Edad , Obesidad/complicaciones , Obesidad/etnología , Análisis de Regresión , Factores de Riesgo , Estados Unidos
14.
Stat Methods Med Res ; 32(7): 1249-1266, 2023 07.
Artículo en Inglés | MEDLINE | ID: mdl-37194551

RESUMEN

The goal of causal mediation analysis, often described within the potential outcomes framework, is to decompose the effect of an exposure on an outcome of interest along different causal pathways. Using the assumption of sequential ignorability to attain non-parametric identification, Imai et al. (2010) proposed a flexible approach to measuring mediation effects, focusing on parametric and semiparametric normal/Bernoulli models for the outcome and mediator. Less attention has been paid to the case where the outcome and/or mediator model are mixed-scale, ordinal, or otherwise fall outside the normal/Bernoulli setting. We develop a simple, but flexible, parametric modeling framework to accommodate the common situation where the responses are mixed continuous and binary, and, apply it to a zero-one inflated beta model for the outcome and mediator. Applying our proposed methods to the publicly-available JOBS II dataset, we (i) argue for the need for non-normal models, (ii) show how to estimate both average and quantile mediation effects for boundary-censored data, and (iii) show how to conduct a meaningful sensitivity analysis by introducing unidentified, scientifically meaningful, sensitivity parameters.


Asunto(s)
Análisis de Mediación , Modelos Estadísticos , Causalidad , Motivación
15.
J Clin Periodontol ; 39(3): 249-55, 2012 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-22092744

RESUMEN

BACKGROUND: Although it is known that periodontal matrix metalloproteinase-8 (MMP-8) expression is associated with periodontal disease, the information concerning the periodontal MMP-8 expression in diabetic patients with periodontal disease is insufficient. MATERIALS AND METHODS: Periodontal tissue specimens were collected from seven patients without periodontal disease and diabetes (Group 1), 15 patients with periodontal disease alone (Group 2) and 10 patients with both periodontal disease and diabetes (Group 3). The frozen sections were prepared and MMP-8 protein expression was detected using immunohistochemistry and quantified. For in vitro study, human U937 mononuclear cells were pre-exposed to normal or high glucose and then treated with lipopolysaccharide (LPS). RESULTS: The nonparametric Kruskal-Wallis test showed that the difference in MMP-8 protein levels among the three groups were statistically significant (p = 0.003). Nonparametric analysis using Jonckheere-Terpstra test showed a tendency of increase in periodontal MMP-8 levels across Group 1 to Group 2 to Group 3 (p = 0.0002). In vitro studies showed that high glucose and LPS had a synergistic effect on MMP-8 expression. CONCLUSION: Our current study showed an increasing trend in MMP-8 protein expression levels across patients without both periodontal disease and diabetes, patients with periodontal disease alone and patients with both diseases.


Asunto(s)
Diabetes Mellitus Tipo 2/enzimología , Regulación Enzimológica de la Expresión Génica , Gingivitis/enzimología , Metaloproteinasa 8 de la Matriz/biosíntesis , Periodontitis/enzimología , Adulto , Anciano , Análisis de Varianza , Estudios de Casos y Controles , Diabetes Mellitus Tipo 2/complicaciones , Etnicidad , Femenino , Gingivitis/complicaciones , Humanos , Hiperglucemia/metabolismo , Procesamiento de Imagen Asistido por Computador , Lipopolisacáridos/metabolismo , Masculino , Metaloproteinasa 8 de la Matriz/genética , Persona de Mediana Edad , Periodontitis/complicaciones , Periodoncio/enzimología , Estadísticas no Paramétricas , Células U937
16.
Pediatr Cardiol ; 33(7): 1154-9, 2012 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-22411716

RESUMEN

Despite the emerging relevance of high-density lipoprotein (HDL) in the inflammatory cascade and vascular barrier integrity, HDL levels in children undergoing cardiac surgery are unexplored. As a measure of HDL levels, the HDL-cholesterol (HDL-C) in single-ventricle patients was quantified before and after the Fontan operation, and it was determined whether relationships existed between the duration and the type of postoperative pleural effusions. The study prospectively enrolled 12 children undergoing the Fontan operation. Plasma HDL-C levels were measured before and after cardiopulmonary bypass. The outcome variables of interest were the duration and type of chest tube drainage (chylous vs. nonchylous). The Kendall rank correlation coefficient and the Wilcoxon rank sum test were used. There were 11 complete observations. The median preoperative HDL-C level for all the subjects was 30 mg/dl (range, 24-53 mg/dl), and the median postcardiopulmonary bypass level was 21 mg/dl (range, 14-46 mg/dl) (p = 0.004). There was a tendency toward a moderate inverse correlation (-0.42) between the postcardiopulmonary bypass HDL-C level and the duration of chest tube drainage, but the result was not statistically significant (p = 0.07). In the chylous effusion group, the median postcardiopulmonary bypass HDL-C tended to be lower (16 vs. 23 mg/dl; p = 0.09). After the Fontan operation, the plasma HDL-C levels in children are significantly reduced. It is reasonable to conclude that the reduction in HDL-C reflects reduced plasma levels of HDL particles, which may have pertinent implications in postoperative pleural effusions given the antiinflammatory and endothelial barrier functions of HDL.


Asunto(s)
HDL-Colesterol/sangre , Procedimiento de Fontan , Cardiopatías Congénitas/sangre , Cardiopatías Congénitas/cirugía , Puente Cardiopulmonar , Tubos Torácicos , Niño , Preescolar , Femenino , Humanos , Lactante , Masculino , Derrame Pleural/sangre , Complicaciones Posoperatorias/sangre , Estudios Prospectivos , Estadísticas no Paramétricas , Resultado del Tratamiento
17.
BMC Bioinformatics ; 12: 438, 2011 Nov 11.
Artículo en Inglés | MEDLINE | ID: mdl-22078224

RESUMEN

BACKGROUND: To utilize the large volume of gene expression information generated from different microarray experiments, several meta-analysis techniques have been developed. Despite these efforts, there remain significant challenges to effectively increasing the statistical power and decreasing the Type I error rate while pooling the heterogeneous datasets from public resources. The objective of this study is to develop a novel meta-analysis approach, Consistent Differential Expression Pattern (CDEP), to identify genes with common differential expression patterns across different datasets. RESULTS: We combined False Discovery Rate (FDR) estimation and the non-parametric RankProd approach to estimate the Type I error rate in each microarray dataset of the meta-analysis. These Type I error rates from all datasets were then used to identify genes with common differential expression patterns. Our simulation study showed that CDEP achieved higher statistical power and maintained low Type I error rate when compared with two recently proposed meta-analysis approaches. We applied CDEP to analyze microarray data from different laboratories that compared transcription profiles between metastatic and primary cancer of different types. Many genes identified as differentially expressed consistently across different cancer types are in pathways related to metastatic behavior, such as ECM-receptor interaction, focal adhesion, and blood vessel development. We also identified novel genes such as AMIGO2, Gem, and CXCL11 that have not been shown to associate with, but may play roles in, metastasis. CONCLUSIONS: CDEP is a flexible approach that borrows information from each dataset in a meta-analysis in order to identify genes being differentially expressed consistently. We have shown that CDEP can gain higher statistical power than other existing approaches under a variety of settings considered in the simulation study, suggesting its robustness and insensitivity to data variation commonly associated with microarray experiments. AVAILABILITY: CDEP is implemented in R and freely available at: http://genomebioinfo.musc.edu/CDEP/. CONTACT: zhengw@musc.edu.


Asunto(s)
Perfilación de la Expresión Génica/métodos , Metástasis de la Neoplasia , Regulación Neoplásica de la Expresión Génica , Humanos , Metaanálisis como Asunto , Análisis de Secuencia por Matrices de Oligonucleótidos/métodos
18.
Bioinformatics ; 26(17): 2183-9, 2010 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-20628070

RESUMEN

MOTIVATION: Highly sensitive and specific screening tools may reduce disease -related mortality by enabling physicians to diagnose diseases in asymptomatic patients or at-risk individuals. Diagnostic tests based on multiple biomarkers may achieve the needed sensitivity and specificity to realize this clinical gain. RESULTS: Logic regression, a multivariable regression method predicting an outcome using logical combinations of binary predictors, yields interpretable models of the complex interactions in biologic systems. However, its performance degrades in noisy data. We extend logic regression for classification to an ensemble of logic trees (Logic Forest, LF). We conduct simulation studies comparing the ability of logic regression and LF to identify variable interactions predictive of disease status. Our findings indicate LF is superior to logic regression for identifying important predictors. We apply our method to single nucleotide polymorphism data to determine associations of genetic and health factors with periodontal disease. AVAILABILITY: LF code is publicly available on CRAN, http://cran.r-project.org/.


Asunto(s)
Biomarcadores/análisis , Modelos Biológicos , Análisis de Regresión , Simulación por Computador , Humanos , Análisis Multivariante , Enfermedades Periodontales/diagnóstico , Enfermedades Periodontales/genética , Polimorfismo de Nucleótido Simple
19.
J Public Health Dent ; 71(2): 143-51, 2011.
Artículo en Inglés | MEDLINE | ID: mdl-21774138

RESUMEN

OBJECTIVES: Assess periodontal disease progression among GullahAfrican Americans with type 2 diabetes mellitus (T2DM) according to health insurance coverage. METHODS: From an ongoing clinical trial among T2DM Gullah, we extracted a cohort that was previously enrolled in a cross-sectional study (N=93). Comparing prior exam to trial initiation, total tooth sites/person with periodontal disease progression events [evaluated separately: 2+ mm of clinical attachment loss (CAL), 2+ mm increased periodontal probing depths (PPD), bleeding on probing (BOP) emergence] were evaluated according to health insurance coverage using regression techniques appropriate for data with different counts of potential events per subject (varying tooth sites available). We used negative binomial regression techniques to account for overdispersion and fit multivariable models that also included baseline glycemic control (poor: glycated hemoglobin > OR =7 percent, well: glycated hemoglobin <7 percent), history of established periodontitis, age, gender, body mass index, annual income, and oral hygiene behaviors. Final models included health insurance status, other significant predictors, and any observed confounders. RESULTS: Privately insured were most prevalent (41.94 percent), followed by uninsured (23.66 percent), Medicare (19.35 percent), and Medicaid (15.05 percent). Those with poor glycemic control (65.59 percent) were more prevalent than well-controlled (34.41 percent). CAL events ranged from 0 to 58.8 percent tooth sites/ person (11.83 +/- 12.44 percent), while PPD events ranged from 0 to 44.2 percent (8.66 +/- 10.97 percent) and BOP events ranged from 0 to 95.8 percent (23.65 +/- 17.21 percent). Rates of CAL events were increased among those who were uninsured [rate ratio (RR) = 1.75, P = 0.02], Medicare-insured (RR = 1.90, P = 0.03), and Medicaid-insured (RR = 1.89, P = 0.06). CONCLUSIONS: Increased access to health care, including dental services, may achieve reduction in chronic periodontal disease progression (as determined by CAL) for this study population. These results are very timely given the March 2010 passing of the US healthcare reform bills.


Asunto(s)
Negro o Afroamericano/etnología , Diabetes Mellitus Tipo 2/complicaciones , Cobertura del Seguro , Seguro de Salud , Enfermedades Periodontales/fisiopatología , Adulto , Factores de Edad , Anciano , Índice de Masa Corporal , Periodontitis Crónica/complicaciones , Periodontitis Crónica/fisiopatología , Estudios de Cohortes , Estudios Transversales , Diabetes Mellitus Tipo 2/sangre , Progresión de la Enfermedad , Femenino , Hemorragia Gingival/complicaciones , Hemorragia Gingival/fisiopatología , Hemoglobina Glucada/análisis , Humanos , Renta , Masculino , Medicaid , Pacientes no Asegurados , Medicare , Persona de Mediana Edad , Higiene Bucal , Pérdida de la Inserción Periodontal/complicaciones , Pérdida de la Inserción Periodontal/fisiopatología , Enfermedades Periodontales/complicaciones , Bolsa Periodontal/complicaciones , Bolsa Periodontal/fisiopatología , Factores Sexuales , South Carolina , Estados Unidos
20.
Nurs Rep ; 11(2): 242-252, 2021 Apr 12.
Artículo en Inglés | MEDLINE | ID: mdl-34968202

RESUMEN

Diabetes is a public health problem and a major risk factor for cardiovascular disease, the leading cause of death in the United States. Diabetes is prevalent among underserved rural populations. The purposes of this study were to perform secondary analyses of existing clinical trial data to determine whether a diabetes health promotion and disease risk reduction intervention had an effect on diabetes fatalism, social support, and perceived diabetes self-management and to provide precise estimates of the mean levels of these variables in an understudied population. Data were collected during a cluster randomized trial implemented among African American participants (n = 146) in a rural, southern area and analyzed using a linear mixed model. The results indicated that the intervention had no significant effect on perceived diabetes management (p = 0.8), diabetes fatalism (p = 0.3), or social support (p = 0.4). However, the estimates showed that, in the population, diabetes fatalism levels were moderate (95% CI = (27.6, 31.3)), and levels of social support (CI = (4.0, 4.4)) and perceived diabetes self-management (CI = (27.7, 29.3)) were high. These findings suggest that diabetes fatalism, social support, and self-management perceptions influence diabetes self-care and rural health outcomes and should be addressed in diabetes interventions.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA