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1.
Dermatol Surg ; 48(8): 815-821, 2022 08 01.
Artículo en Inglés | MEDLINE | ID: mdl-35917262

RESUMEN

BACKGROUND: Although vitiligo is often treated medically, there is increasing evidence for surgical therapies. Overlap with in-office surgical therapies that are already employed for other dermatologic conditions suggest that there is a significant opportunity to expand dermatologists' therapeutic repertoire for vitiligo. OBJECTIVE: To systematically review the efficacy of nonphototherapy surgical treatments for vitiligo in comparative or placebo-controlled trials. METHODS: A systematic review for surgical treatments for vitiligo was conducted. Primary outcomes were treatment success (>75% repigmentation) and failure (<25% repigmentation) for which meta-analyses were performed. Adverse effects were noted. The Cochrane risk of bias tool was used to assess study quality. RESULTS: Surgical treatments reviewed included platelet-rich plasma, microneedling, ablative therapies, and surgical modalities. Seventy-three studies with 2,911 patients were included. The repigmentation benefits and adverse events are summarized. Meta-analyses suggest benefits for ablative laser therapies or microneedling in combination with narrowband ultraviolet B (NB-UVB) and for suction blister epidermal grafting over punch grafting. CONCLUSION: The addition of microneedling or ablative laser therapy to NB-UVB phototherapy may improve repigmentation with minimal adverse effects. Surgical therapies, such as suction blister grafting and punch grafting, may offer the highest likelihood of repigmentation but have a risk of adverse effects including scarring and hyperpigmentation.


Asunto(s)
Terapia Ultravioleta , Vitíligo , Vesícula/etiología , Terapia Combinada , Humanos , Fototerapia , Resultado del Tratamiento , Vitíligo/tratamiento farmacológico , Vitíligo/cirugía
2.
J Nutr ; 151(4): 930-939, 2021 04 08.
Artículo en Inglés | MEDLINE | ID: mdl-33693725

RESUMEN

BACKGROUND: Exogenous exposures collectively may contribute to chronic, low-grade inflammation and increase risks for major chronic diseases and mortality. We previously developed, validated, and reported a novel, FFQ-based and lifestyle questionnaire-based, inflammation biomarker panel-weighted, predominantly whole foods-based 19-component dietary inflammation score (DIS) and 4-component lifestyle inflammation score (LIS; comprising physical activity, alcohol intake, BMI, and current smoking status). Both scores were more strongly associated with circulating biomarkers of inflammation in 3 populations than were previously reported dietary inflammation indices. Associations of the DIS and LIS with mortality risk have not been reported. OBJECTIVES: To investigate separate and joint associations of the DIS and LIS with all-cause, all-cancer, and cardiovascular disease (CVD) mortality risks in the prospective Iowa Women's Health Study (1986-2012; n = 33,155 women, ages 55-69 years, of whom 17,431 died during follow-up, including 4379 from cancer and 6574 from CVD). METHODS: We summed each study participant's scores' components, weighted by their published weights, to yield the participant's inflammation score; a higher score was considered more pro-inflammatory. We assessed DIS and LIS mortality associations using multivariable Cox proportional hazards regression. RESULTS: Among participants in the highest relative to the lowest DIS and LIS quintiles, the adjusted HRs for all-cause mortality were 1.11 (95% CI: 1.05-1.16) and 1.60 (95% CI: 1.53-1.68), respectively; for all-cancer mortality were 1.07 (95% CI: 0.97-1.17) and 1.51 (95% CI: 1.38-1.66), respectively; and for CVD mortality were 1.12 (95% CI: 1.03-1.21) and 1.79 (95% CI: 1.66-1.94), respectively (all Ptrend values < 0.01). Among those in the highest relative to the lowest joint LIS/DIS quintiles, the HRs for all-cause, all-cancer, and all-CVD mortality were 1.88 (95% CI: 1.71-2.08), 1.82 (95% CI: 1.50-2.20), and 1.92 (95% CI: 1.64-2.24), respectively. CONCLUSIONS: More pro-inflammatory diets and lifestyles, separately but especially jointly, may be associated with higher all-cause, all-cancer, and all-CVD mortality risks among women.


Asunto(s)
Enfermedades Cardiovasculares/mortalidad , Dieta/efectos adversos , Estilo de Vida , Neoplasias/mortalidad , Anciano , Biomarcadores/análisis , Estudios de Cohortes , Femenino , Factores de Riesgo de Enfermedad Cardiaca , Humanos , Inflamación/etiología , Iowa/epidemiología , Persona de Mediana Edad , Estudios Prospectivos , Factores de Riesgo , Encuestas y Cuestionarios
3.
Nutr Cancer ; 73(11-12): 2323-2335, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-32981353

RESUMEN

BACKGROUND: Basic science literature strongly supports a role of oxidative stress in colorectal cancer (CRC) etiology, but in epidemiologic studies, associations of most individual exposures with CRC have been weak or inconsistent. However, recent epidemiologic evidence suggests that the collective effects of these exposures on oxidative balance and CRC risk may be substantial. METHODS: Using food frequency and lifestyle questionnaire data from the prospective Iowa Women's Health Study (1986-2012), we investigated associations of 11-component dietary and 4-component lifestyle oxidative balance scores (OBS) with incident CRC using multivariable Cox proportional hazards regression. RESULTS: Of the 33,736 cancer-free women aged 55-69 years at baseline, 1,632 developed CRC during follow-up. Among participants in the highest relative to the lowest dietary and lifestyle OBS quintiles (higher anti-oxidant relative to pro-oxidant exposures), the adjusted hazard ratios (HRs) and their 95% confidence intervals (CI) were, respectively, 0.77 (0.63, 0.94) (Ptrend=0.02) and 0.61 (0.52, 0.71) (Ptrend<0.0001). Among those in the highest relative to the lowest joint lifestyle/dietary OBS quintile, the HR was 0.45 (95% CI 0.26, 0.77). CONCLUSIONS: Our findings suggest that a predominance of antioxidant over pro-oxidant dietary and lifestyle exposures-separately and especially jointly-may be inversely associated with CRC risk among older women.


Asunto(s)
Neoplasias Colorrectales , Anciano , Neoplasias Colorrectales/epidemiología , Neoplasias Colorrectales/etiología , Dieta , Femenino , Humanos , Iowa/epidemiología , Estilo de Vida , Persona de Mediana Edad , Estrés Oxidativo , Modelos de Riesgos Proporcionales , Estudios Prospectivos , Factores de Riesgo , Salud de la Mujer
4.
Am J Epidemiol ; 187(9): 1923-1930, 2018 09 01.
Artículo en Inglés | MEDLINE | ID: mdl-29788105

RESUMEN

Concentration of 25-hydroxyvitamin D3 (25(OH)D3), the main circulating form of vitamin D, is inversely associated with incident, sporadic colorectal adenoma risk. We investigated whether this association differs by 2 functional variants in the vitamin D-binding protein (DBP) gene, group-specific component (GC), that encode for common protein isoforms Gc1s, Gc1f, and Gc2 linked to differences in vitamin D metabolism. We pooled data (418 patients with adenoma and 524 polyp-free control subjects) from 3 colonoscopy-based case-control studies (Minnesota, 1991-1994; North Carolina, 1994-1997; South Carolina, 2002). We estimated 25(OH)D3-adenoma associations, stratified by DBP isoforms, using multivariable logistic regression. Higher 25(OH)D3 concentrations were inversely associated with colorectal adenoma risk among those with the Gc2 isoform (per 10-ng/mL increase in 25(OH)D3, odds ratio = 0.71, 95% confidence interval: 0.56, 0.90), but not among those with only Gc1 isoforms (odds ratio = 1.07, 95% confidence interval: 0.87, 1.32; P for interaction = 0.03). Thus, the vitamin D-incident, sporadic colorectal adenoma association may differ by common DBP isoforms, and patients with the Gc2 isoform may particularly benefit from maintaining higher circulating 25(OH)D3 concentrations for adenoma prevention.


Asunto(s)
Adenoma/genética , Calcifediol/sangre , Neoplasias Colorrectales/genética , Proteína de Unión a Vitamina D/genética , Adenoma/sangre , Adulto , Anciano , Estudios de Casos y Controles , Neoplasias Colorrectales/sangre , Femenino , Humanos , Masculino , Persona de Mediana Edad , Isoformas de Proteínas
7.
J Neurosurg Spine ; 41(4): 551-558, 2024 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-38996396

RESUMEN

OBJECTIVE: The primary goal of this study was to establish the current microbial trends in vertebral osteomyelitis/discitis (VOD) amid the opioid epidemic and to determine if intravenous drug use (IVDU) predisposes one to a unique microbial profile of infection. METHODS: The authors performed a retrospective cohort study consisting of 1175 adult patients diagnosed with VOD between 2011 and 2022 at a single quaternary center. Data were acquired through retrospective chart review, with pertinent demographic and clinical information collected. RESULTS: Staphylococcus aureus was the most cultured organism in both the IVDU and non-IVDU groups at 56.1% and 40.7%, respectively. In the IVDU cohort, Serratia marcescens was the next most prevalently cultured organism at 13.9%. CONCLUSIONS: The present study demonstrates that in the IVDU population S. marcescens is an organism of high concern. The potential for Serratia spp. infection should be accounted for when selecting empirical antimicrobial therapy in VOD patients.


Asunto(s)
Discitis , Osteomielitis , Serratia marcescens , Humanos , Osteomielitis/microbiología , Osteomielitis/epidemiología , Osteomielitis/tratamiento farmacológico , Femenino , Masculino , Estudios Retrospectivos , Persona de Mediana Edad , Discitis/microbiología , Discitis/epidemiología , Discitis/tratamiento farmacológico , Adulto , Epidemia de Opioides , Staphylococcus aureus , Infecciones Estafilocócicas/epidemiología , Infecciones Estafilocócicas/tratamiento farmacológico , Infecciones Estafilocócicas/microbiología , Anciano , Abuso de Sustancias por Vía Intravenosa/complicaciones , Abuso de Sustancias por Vía Intravenosa/epidemiología , Infecciones por Serratia/epidemiología , Infecciones por Serratia/tratamiento farmacológico , Infecciones por Serratia/microbiología , Antibacterianos/uso terapéutico
8.
Sci Adv ; 8(23): eabn3328, 2022 Jun 10.
Artículo en Inglés | MEDLINE | ID: mdl-35675391

RESUMEN

In 1995, journalist Gary Taubes published an article in Science titled "Epidemiology faces its limits," which questioned the utility of nonrandomized epidemiologic research and has since been cited more than 1000 times. He highlighted numerous examples of research topics he viewed as having questionable merit. Studies have since accumulated for these associations. We systematically evaluated current evidence of 53 example associations discussed in the article. Approximately one-quarter of those presented as doubtful are now widely viewed as causal based on current evaluations of the public health consensus. They include associations between alcohol consumption and breast cancer, residential radon exposure and lung cancer, and the use of tanning devices and melanoma. This history should inform current debates about the reproducibility of epidemiologic research results.

9.
Curr Oncol ; 28(6): 4756-4771, 2021 11 16.
Artículo en Inglés | MEDLINE | ID: mdl-34898573

RESUMEN

Genome-wide association studies (GWAS) and candidate pathway studies have identified low-penetrant genetic variants associated with cutaneous melanoma. We investigated the association of melanoma-risk variants with primary melanoma tumor prognostic characteristics and melanoma-specific survival. The Genes, Environment, and Melanoma Study enrolled 3285 European origin participants with incident invasive primary melanoma. For each of 47 melanoma-risk single nucleotide polymorphisms (SNPs), we used linear and logistic regression modeling to estimate, respectively, the per allele mean changes in log of Breslow thickness and odds ratios for presence of ulceration, mitoses, and tumor-infiltrating lymphocytes (TILs). We also used Cox proportional hazards regression modeling to estimate the per allele hazard ratios for melanoma-specific survival. Passing the false discovery threshold (p = 0.0026) were associations of IRF4 rs12203592 and CCND1 rs1485993 with log of Breslow thickness, and association of TERT rs2242652 with presence of mitoses. IRF4 rs12203592 also had nominal associations (p < 0.05) with presence of mitoses and melanoma-specific survival, as well as a borderline association (p = 0.07) with ulceration. CCND1 rs1485993 also had a borderline association with presence of mitoses (p = 0.06). MX2 rs45430 had nominal associations with log of Breslow thickness, presence of mitoses, and melanoma-specific survival. Our study indicates that further research investigating the associations of these genetic variants with underlying biologic pathways related to tumor progression is warranted.


Asunto(s)
Melanoma , Neoplasias Cutáneas , Estudio de Asociación del Genoma Completo , Humanos , Linfocitos Infiltrantes de Tumor/patología , Melanoma/genética , Melanoma/patología , Pronóstico , Neoplasias Cutáneas/genética , Neoplasias Cutáneas/patología
10.
J Invest Dermatol ; 138(11): 2398-2404, 2018 11.
Artículo en Inglés | MEDLINE | ID: mdl-29753029

RESUMEN

BRAF and NRAS mutations arise early in melanoma development, but their associations with low-penetrance melanoma susceptibility loci remain unknown. In the Genes, Environment and Melanoma Study, 1,223 European-origin participants had their incident invasive primary melanomas screened for BRAF/NRAS mutations and germline DNA genotyped for 47 single-nucleotide polymorphisms identified as low-penetrant melanoma-risk variants. We used multinomial logistic regression to simultaneously examine each single-nucleotide polymorphism's relationship to BRAF V600E, BRAF V600K, BRAF other, and NRAS+ relative to BRAF-/NRAS- melanoma adjusted for study features. IRF4 rs12203592*T was associated with BRAF V600E (odds ratio [OR] = 0.59, 95% confidence interval [CI] = 0.43-0.79) and V600K (OR = 0.65, 95% CI = 0.41-1.03), but not BRAF other or NRAS+ melanoma. A global test of etiologic heterogeneity (Pglobal = 0.001) passed false discovery (Pglobal = 0.0026). PLA2G6 rs132985*T was associated with BRAF V600E (OR = 1.32, 95% CI = 1.05-1.67) and BRAF other (OR = 1.82, 95% CI = 1.11-2.98), but not BRAF V600K or NRAS+ melanoma. The test for etiologic heterogeneity (Pglobal) was 0.005. The IRF4 rs12203592 associations were slightly attenuated after adjustment for melanoma-risk phenotypes. The PLA2G6 rs132985 associations were independent of phenotypes. IRF4 and PLA2G6 inherited genotypes may influence melanoma BRAF/NRAS subtype development.


Asunto(s)
GTP Fosfohidrolasas/genética , Genotipo , Fosfolipasas A2 Grupo VI/genética , Factores Reguladores del Interferón/genética , Melanoma/genética , Proteínas de la Membrana/genética , Mutación/genética , Proteínas Proto-Oncogénicas B-raf/genética , Neoplasias Cutáneas/genética , Adulto , Anciano , Femenino , Estudios de Asociación Genética , Humanos , Masculino , Persona de Mediana Edad , Polimorfismo de Nucleótido Simple , Riesgo
11.
J Invest Dermatol ; 137(12): 2588-2598, 2017 12.
Artículo en Inglés | MEDLINE | ID: mdl-28842324

RESUMEN

Associations of MC1R with BRAF mutations in melanoma have been inconsistent between studies. We sought to determine for 1,227 participants in the international population-based Genes, Environment, and Melanoma (GEM) study whether MC1R and phenotypes were associated with melanoma BRAF/NRAS subtypes. We used logistic regression adjusted by age, sex, and study design features and examined effect modifications. BRAF+ were associated with younger age, blond/light brown hair, increased nevi, and less freckling, and NRAS+ with older age relative to the wild type (BRAF-/NRAS-) melanomas (all P < 0.05). Comparing specific BRAF subtypes to the wild type, BRAF V600E was associated with younger age, blond/light brown hair, and increased nevi and V600K with increased nevi and less freckling (all P < 0.05). MC1R was positively associated with BRAF V600E cases but only among individuals with darker phototypes or darker hair (Pinteraction < 0.05) but inversely associated with BRAF V600K (Ptrend = 0.006) with no significant effect modification by phenotypes. These results support distinct etiologies for BRAF V600E, BRAF V600K, NRAS+, and wild-type melanomas. MC1R's associations with BRAF V600E cases limited to individuals with darker phenotypes indicate that MC1R genotypes specifically provide information about BRAF V600E melanoma risk in those not considered high risk based on phenotype. Our results also suggest that melanin pathways deserve further study in BRAF V600E melanomagenesis.


Asunto(s)
GTP Fosfohidrolasas/genética , Melanoma/genética , Proteínas de la Membrana/genética , Proteínas Proto-Oncogénicas B-raf/genética , Receptor de Melanocortina Tipo 1/genética , Neoplasias Cutáneas/genética , Adulto , Anciano , Australia , Femenino , Genotipo , Humanos , Masculino , Persona de Mediana Edad , Mutación , Fenotipo , Estados Unidos
12.
J Natl Cancer Inst ; 108(7)2016 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-26857527

RESUMEN

BACKGROUND: Solar elastosis and neval remnants are histologic markers characteristic of divergent melanoma pathways linked to differences in age at onset, host phenotype, and sun exposure. However, the association between these pathway markers and newly identified low-penetrance melanoma susceptibility loci remains unknown. METHODS: In the Genes, Environment and Melanoma (GEM) Study, 2103 Caucasian participants had first primary melanomas that underwent centralized pathology review. For 47 single-nucleotide polymorphisms (SNPs) previously identified as low-penetrant melanoma risk variants, we used multinomial logistic regression to compare melanoma with solar elastosis and melanoma with neval remnants simultaneously to melanoma with neither of these markers, excluding melanomas with both markers. All statistical tests were two-sided. RESULTS: IRF4 rs12203592 was the only SNP to pass the false discovery threshold in baseline models adjusted for age, sex, and study center. rs12203592*T was associated positively with melanoma with solar elastosis (odds ratio [OR] = 1.47, 95% confidence interval [CI] = 1.18 to 1.82) and inversely with melanoma with neval remnants (OR = 0.65, 95% CI = 0.48 to 0.87) compared with melanoma with neither marker (P global = 3.78 x 10(-08)). Adjusting for phenotypic characteristics and total sun exposure hours did not materially affect rs12203592's associations. Distinct early- and late-onset age distributions were observed in patients with IRF4 rs12203592 [CC] and [TT] genotypes, respectively. CONCLUSIONS: Our findings suggest a role of IRF4 rs12203592 in pathway-specific risk for melanoma development. We hypothesize that IRF4 rs12203592 could underlie in part the bimodal age distribution reported for melanoma and linked to the divergent pathways.


Asunto(s)
Factores Reguladores del Interferón/genética , Melanoma/genética , Melanoma/patología , Polimorfismo de Nucleótido Simple , Neoplasias Cutáneas/genética , Neoplasias Cutáneas/patología , Adulto , Edad de Inicio , Anciano , Femenino , Predisposición Genética a la Enfermedad , Genotipo , Humanos , Modelos Logísticos , Masculino , Persona de Mediana Edad , Oportunidad Relativa , Fenotipo , Análisis de Componente Principal , Luz Solar/efectos adversos , Población Blanca/genética
13.
Cancer Epidemiol Biomarkers Prev ; 24(6): 992-7, 2015 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-25837821

RESUMEN

Recent studies, including genome-wide association studies, have identified several putative low-penetrance susceptibility loci for melanoma. We sought to determine their generalizability to genetic predisposition for multiple primary melanoma in the international population-based Genes, Environment, and Melanoma (GEM) Study. GEM is a case-control study of 1,206 incident cases of multiple primary melanoma and 2,469 incident first primary melanoma participants as the control group. We investigated the odds of developing multiple primary melanoma for 47 SNPs from 21 distinct genetic regions previously reported to be associated with melanoma. ORs and 95% confidence intervals were determined using logistic regression models adjusted for baseline features (age, sex, age by sex interaction, and study center). We investigated univariable models and built multivariable models to assess independent effects of SNPs. Eleven SNPs in 6 gene neighborhoods (TERT/CLPTM1L, TYRP1, MTAP, TYR, NCOA6, and MX2) and a PARP1 haplotype were associated with multiple primary melanoma. In a multivariable model that included only the most statistically significant findings from univariable modeling and adjusted for pigmentary phenotype, back nevi, and baseline features, we found TERT/CLPTM1L rs401681 (P = 0.004), TYRP1 rs2733832 (P = 0.006), MTAP rs1335510 (P = 0.0005), TYR rs10830253 (P = 0.003), and MX2 rs45430 (P = 0.008) to be significantly associated with multiple primary melanoma, while NCOA6 rs4911442 approached significance (P = 0.06). The GEM Study provides additional evidence for the relevance of these genetic regions to melanoma risk and estimates the magnitude of the observed genetic effect on development of subsequent primary melanoma.


Asunto(s)
Biomarcadores de Tumor/genética , Predisposición Genética a la Enfermedad , Haplotipos/genética , Melanoma/genética , Polimorfismo de Nucleótido Simple/genética , Neoplasias Cutáneas/genética , Australia/epidemiología , Canadá/epidemiología , Estudios de Casos y Controles , Europa (Continente)/epidemiología , Estudios de Seguimiento , Estudio de Asociación del Genoma Completo , Humanos , Agencias Internacionales , Melanoma/epidemiología , Melanoma/patología , Invasividad Neoplásica , Estadificación de Neoplasias , Fenotipo , Pronóstico , Neoplasias Cutáneas/epidemiología , Neoplasias Cutáneas/patología , Estados Unidos/epidemiología
14.
Clin Cancer Res ; 21(9): 2167-76, 2015 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-25934889

RESUMEN

PURPOSE: IL2 inducible T-cell kinase (ITK) promoter CpG sites are hypomethylated in melanomas compared with nevi. The expression of ITK in melanomas, however, has not been established and requires elucidation. EXPERIMENTAL DESIGN: An ITK-specific monoclonal antibody was used to probe sections from deidentified, formalin-fixed paraffin-embedded tumor blocks or cell line arrays and ITK was visualized by IHC. Levels of ITK protein differed among melanoma cell lines and representative lines were transduced with four different lentiviral constructs that each contained an shRNA designed to knockdown ITK mRNA levels. The effects of the selective ITK inhibitor BI 10N on cell lines and mouse models were also determined. RESULTS: ITK protein expression increased with nevus to metastatic melanoma progression. In melanoma cell lines, genetic or pharmacologic inhibition of ITK decreased proliferation and migration and increased the percentage of cells in the G0-G1 phase. Treatment of melanoma-bearing mice with BI 10N reduced growth of ITK-expressing xenografts or established autochthonous (Tyr-Cre/Pten(null)/Braf(V600E)) melanomas. CONCLUSIONS: We conclude that ITK, formerly considered an immune cell-specific protein, is aberrantly expressed in melanoma and promotes tumor development and progression. Our finding that ITK is aberrantly expressed in most metastatic melanomas suggests that inhibitors of ITK may be efficacious for melanoma treatment. The efficacy of a small-molecule ITK inhibitor in the Tyr-Cre/Pten(null)/Braf(V600E) mouse melanoma model supports this possibility.


Asunto(s)
Melanoma/enzimología , Proteínas Tirosina Quinasas/biosíntesis , Neoplasias Cutáneas/enzimología , Animales , Antineoplásicos/farmacología , Western Blotting , Línea Celular Tumoral , Modelos Animales de Enfermedad , Electroforesis en Gel Bidimensional , Técnicas de Silenciamiento del Gen , Humanos , Procesamiento de Imagen Asistido por Computador , Inmunohistoquímica , Melanoma/patología , Ratones , Análisis de Secuencia por Matrices de Oligonucleótidos , Inhibidores de Proteínas Quinasas/farmacología , Proteínas Tirosina Quinasas/antagonistas & inhibidores , Neoplasias Cutáneas/patología , Análisis de Matrices Tisulares , Ensayos Antitumor por Modelo de Xenoinjerto
15.
Ecol Evol ; 4(11): 2202-16, 2014 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-25360261

RESUMEN

When different life stages have different environmental tolerances, development needs to be regulated so that each life stage experiences environmental conditions that are suitable for it, if fitness is to be maintained. Restricting the timing of developmental transitions to occur under specific combinations of environmental conditions is therefore adaptively important. However, impeding development can itself incur demographic and fitness costs. How do organisms regulate development and physiological processes so that they occur under the broadest range of permissive conditions? Gene duplication offers one solution: Multiple genes contribute to the same downstream process, but do so under distinct combinations of environmental conditions. We present a simple model to examine how environmental sensitivities of genes and how gene duplication influence the distribution of environmental conditions under which an end process will proceed. The model shows that the duplication of genes that retain their downstream function but diverge in environmental sensitivities can allow an end process to proceed under more than one distinct combination of environmental conditions. The outcomes depend on how upstream genes regulate downstream components, which genes in the pathway have diversified in their sensitivities, and the structure of the pathway.

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