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1.
Hepatol Commun ; 7(12)2023 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-38055641

RESUMO

BACKGROUND: Pediatric metabolic-associated fatty liver disease (MAFLD) is a global health problem, with lifestyle modification as its major therapeutic strategy. Rigorous characterization of dietary content on MAFLD in children is lacking. We hypothesized an objectively measured healthier diet would positively modulate MAFLD. METHODS: Diet was assessed using the Nutrition Data System for Research in children enrolled from 10 tertiary clinical centers to determine the Healthy Eating Index (HEI, 0-100) and individual food components. RESULTS: In all, 119 children were included (13.3 ± 2.7 y), 80 (67%) male, 67 (18%) White, and 90 (76%) Hispanic, with an average body mass index Z-score of 2.2 ± 0.5. Diet was classified as low HEI < 47.94 (n = 39), mid HEI ≥ 47.94 and < 58.89 (n = 41), or high HEI ≥ 58.89 (n=39). Children with high HEI (healthier diet) had lower body weight (p = 0.005) and more favorable lipids. Mean serum triglycerides for low, mid, and high HEI were 163, 148, and 120 mg/dL, respectively; p = 0.04 mid versus high, p = 0.01 low versus high. Mean HDL was 38, 41 and 43 mg/dL; p = 0.02 low vs high. Less severe steatosis was noted with added sugar ≤ 10% of calories (p = 0.03). Higher lobular inflammation is associated with a higher percentage of calories from fat (OR (95% CI) = 0.95 (0.91-1.00), p = 0.04). CONCLUSIONS: In children with MAFLD, high HEI is associated with lower body weight and more favorable lipids, while added sugar and fat intake has individual histologic features. Differential consumption of major dietary components may modify both metabolic risk factors and histologic liver injury, highlighting the importance of objective diet assessments in children with MAFLD.


Assuntos
Dieta Saudável , Avaliação Nutricional , Humanos , Masculino , Criança , Feminino , Lipídeos , Açúcares , Peso Corporal
2.
Hepatol Commun ; 7(2): e0033, 2023 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-36724127

RESUMO

BACKGROUND AND AIMS: The NAFLD activity score was developed to measure histologic changes in NAFLD during therapeutic trials. Hepatocyte ballooning (HB) is the most specific feature in steatohepatitis diagnosis, yet the impact of variations in HB has not been incorporated. APPROACH AND RESULTS: Liver biopsies from patients enrolled in the NASH Clinical Research Network with an initial diagnosis of NASH or NAFL (n=1688) were evaluated to distinguish classic hepatocyte ballooning (cHB) from smaller, nonclassic hepatocyte ballooning (nHB), and also to designate severe ballooning and assign an extended hepatocyte ballooning (eB) score [0 points, no ballooning (NB); 1 point, few or many nHB; 2 points, few cHB; 3 points, many cHB; 4 points, severe cHB] to the biopsy assessment. The eB score was reproducible among NASH CRN liver pathologists (weighted kappa 0.76) and was significantly associated with older age (mean 52.1 y, cHB; 48.5 y, nHB, p<0.001), gender (72.3% female, cHB; 54.5% female, nHB, p<0.001), diabetes (49.8% diabetes, cHB; 28.2% diabetes, nHB, p<0.001), metabolic syndrome (68.5% metabolic syndrome, nHB; 50.2% metabolic syndrome, NB, p<0.001), and body mass index [33.2, 34.2, 35 mean body mass index (kg/m2); NB, nHB, and cHB, respectively, p<0.05]. Finally, fibrosis stage, as a marker of disease severity, was significantly correlated with the eB score (p<0.001). CONCLUSIONS: The eB score allows for a reproducible and more precise delineation of the range of ballooned hepatocyte morphology and corresponds with both clinical features of NASH and fibrosis stage.


Assuntos
Síndrome Metabólica , Hepatopatia Gordurosa não Alcoólica , Humanos , Feminino , Masculino , Hepatopatia Gordurosa não Alcoólica/diagnóstico , Hepatopatia Gordurosa não Alcoólica/patologia , Relevância Clínica , Hepatócitos/patologia , Cirrose Hepática/diagnóstico , Cirrose Hepática/patologia
3.
N Engl J Med ; 385(17): 1559-1569, 2021 10 21.
Artigo em Inglês | MEDLINE | ID: mdl-34670043

RESUMO

BACKGROUND: The prognoses with respect to mortality and hepatic and nonhepatic outcomes across the histologic spectrum of nonalcoholic fatty liver disease (NAFLD) are not well defined. METHODS: We prospectively followed a multicenter patient population that included the full histologic spectrum of NAFLD. The incidences of death and other outcomes were compared across baseline histologic characteristics. RESULTS: A total of 1773 adults with NAFLD were followed for a median of 4 years. All-cause mortality increased with increasing fibrosis stages (0.32 deaths per 100 person-years for stage F0 to F2 [no, mild, or moderate fibrosis], 0.89 deaths per 100 persons-years for stage F3 [bridging fibrosis], and 1.76 deaths per 100 person-years for stage F4 [cirrhosis]). The incidence of liver-related complications per 100 person-years increased with fibrosis stage (F0 to F2 vs. F3 vs. F4) as follows: variceal hemorrhage (0.00 vs. 0.06 vs. 0.70), ascites (0.04 vs. 0.52 vs. 1.20), encephalopathy (0.02 vs. 0.75 vs. 2.39), and hepatocellular cancer (0.04 vs. 0.34 vs. 0.14). As compared with patients with stage F0 to F2 fibrosis, patients with stage F4 fibrosis also had a higher incidence of type 2 diabetes (7.53 vs. 4.45 events per 100 person-years) and a decrease of more than 40% in the estimated glomerular filtration rate (2.98 vs. 0.97 events per 100 person-years). The incidence of cardiac events and nonhepatic cancers were similar across fibrosis stages. After adjustment for age, sex, race, diabetes status, and baseline histologic severity, the incidence of any hepatic decompensation event (variceal hemorrhage, ascites, or encephalopathy) was associated with increased all-cause mortality (adjusted hazard ratio, 6.8; 95% confidence interval, 2.2 to 21.3). CONCLUSIONS: In this prospective study involving patients with NAFLD, fibrosis stages F3 and F4 were associated with increased risks of liver-related complications and death. (Funded by the National Institute of Diabetes and Digestive and Kidney Diseases and others; NAFLD DB2 ClinicalTrials.gov number, NCT01030484.).


Assuntos
Cirrose Hepática/mortalidade , Hepatopatia Gordurosa não Alcoólica/mortalidade , Adulto , Biópsia , Carcinoma Hepatocelular/etiologia , Feminino , Hemorragia Gastrointestinal/etiologia , Humanos , Incidência , Fígado/patologia , Cirrose Hepática/complicações , Neoplasias Hepáticas/etiologia , Masculino , Pessoa de Meia-Idade , Hepatopatia Gordurosa não Alcoólica/complicações , Prognóstico , Estudos Prospectivos , Índice de Gravidade de Doença
4.
Liver Int ; 41(5): 996-1011, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33354866

RESUMO

BACKGROUND/AIMS: Glycogen synthesis and storage are normal hepatocyte functions. However, glycogenosis, defined as excess hepatocyte glycogen visible by routine H&E light microscopy, has not been well characterized in nonalcoholic fatty liver disease (NAFLD). METHODS: Glycogenosis in NAFLD liver biopsies was graded as "none", "focal" (in <50% of hepatocytes), or "diffuse" (in ≥50% of hepatocytes). Clinical and pathological variables associated with glycogenosis were assessed. 2047 liver biopsies were prospectively analysed. RESULTS: In adults and children, any glycogenosis was present in 54% of cases; diffuse glycogenosis was noted in approximately 1/3 of cases. On multiple logistic regression analysis, adults with glycogenosis tended to be older (P = .003), female (P = .04), have higher serum glucose (P = .01), and use insulin (P = .02). Adults tended to have lower steatosis scores (P = .006) and lower fibrosis stages (P = .005); however, unexpectedly, they also tended to have more hepatocyte injury including ballooning (P = .003). On multiple logistic regression analysis, paediatric patients with glycogenosis were more likely to be Hispanic (P = .03), have lower body weight (P = .002), elevated triglycerides (P = .001), and a higher fasting glucose (P = .007). Paediatric patients with glycogenosis also had less steatosis (P < .001) than those without. CONCLUSIONS: Glycogenosis is common in adult and paediatric NAFLD, and is associated with clinical features of insulin resistance. Glycogenosis is important to recognize histologically because it may be misinterpreted as ballooning, and when diffuse, confusion with glycogen storage disorders or glycogenic hepatopathy must be avoided. The newly observed dichotomous relationship between glycogenosis and increased liver cell injury but decreased steatosis and fibrosis requires further study.


Assuntos
Doença de Depósito de Glicogênio , Resistência à Insulina , Hepatopatia Gordurosa não Alcoólica , Adulto , Criança , Feminino , Fibrose , Doença de Depósito de Glicogênio/patologia , Humanos , Fígado/patologia , Hepatopatia Gordurosa não Alcoólica/complicações , Hepatopatia Gordurosa não Alcoólica/patologia
5.
Am J Gastroenterol ; 116(5): 994-1006, 2021 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-33306506

RESUMO

INTRODUCTION: This study explored the relationship between patatin-like phospholipase domain-containing 3 gene (PNPLA3 rs738409), nutrient intake, and liver histology severity in patients with nonalcoholic fatty liver disease (NAFLD). METHODS: PNPLA3-rs738409 variant was genotyped in 452 non-Hispanic whites with histologically confirmed NAFLD who completed Food Frequency Questionnaire within 6 months of their liver biopsy. The fibrosis severity on liver histology was the outcome of interest. RESULTS: The distribution of PNPLA3 genotypes was CC: 28%, CG: 46%, and GG: 25%. High-carbohydrate (% of energy/d) intake was positively associated (adjusted [Adj] odds ratio [OR]: 1.03, P < 0.01), whereas higher n-3 polyunsaturated fatty acids (n-3 PUFAs) (g/d) (Adj. OR: 0.17, P < 0.01), isoflavones (mg/d) (Adj. OR: 0.74, P = 0.049), methionine (mg/d) (Adj. OR: 0.32, P < 0.01), and choline (mg/d) (Adj. OR: 0.32, P < 0.01) intakes were inversely associated with increased risk of significant fibrosis (stage of fibrosis ≥2). By using an additive model of inheritance, our moderation analysis showed that PNPLA3 rs738409 significantly modulates the relationship between carbohydrate (%), n-3 PUFAs, total isoflavones, methionine, and choline intakes and fibrosis severity in a dose-dependent, genotype manner. These dietary factors tended to have a larger and significant effect on fibrosis severity among rs738409 G-allele carriers. Associations between significant fibrosis and carbohydrates (Adj. OR: 1.04, P = 0.019), n-3 PUFAs (Adj. OR: 0.16, P < 0.01), isoflavones (Adj. OR: 0.65, P = 0.025), methionine (Adj. OR: 0.30, P < 0.01), and total choline (Adj. OR: 0.29, P < 0.01) intakes remained significant only among rs738409 G-allele carriers. DISCUSSION: This gene-diet interaction study suggests that PNPLA3 rs738409 G-allele might modulate the effect of specific dietary nutrients on risk of fibrosis in patients with NAFLD.


Assuntos
Inquéritos sobre Dietas , Lipase/genética , Cirrose Hepática/genética , Proteínas de Membrana/genética , Hepatopatia Gordurosa não Alcoólica/genética , Adulto , Biópsia , Feminino , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Risco , Índice de Gravidade de Doença
6.
JAMA Netw Open ; 2(10): e1912565, 2019 10 02.
Artigo em Inglês | MEDLINE | ID: mdl-31584681

RESUMO

Importance: The histologic evolution of the full spectrum of nonalcoholic fatty liver disease (NAFLD) and factors associated with progression or regression remain to be definitively established. Objective: To evaluate the histologic evolution of NAFLD and the factors associated with changes in disease severity over time. Design, Setting, and Participants: A prospective cohort substudy from the Nonalcoholic Steatohepatitis Clinical Research Network (NASH CRN) NAFLD Database study, a noninterventional registry, was performed at 8 university medical research centers. Masked assessment of liver histologic specimens was performed, using a prespecified protocol to score individual biopsies. Participants included 446 adults with NAFLD enrolled in the NASH CRN Database studies between October 27, 2004, and September 13, 2013, who underwent 2 liver biopsies 1 or more year apart. Data analysis was performed from October 2016 to October 2018. Main Outcomes and Measures: Progression and regression of fibrosis stage, using clinical, laboratory, and histologic findings, including the NAFLD activity score (NAS) (sum of scores for steatosis, lobular inflammation, and ballooning; range, 0-8, with 8 indicating more severe disease). Results: A total of 446 adults (mean [SD] age, 47 [11] years; 294 [65.9%] women) with NAFLD (NAFL, 86 [19.3%]), borderline NASH (84 [18.8%]), and definite NASH (276 [61.9%]) were studied. Over a mean (SD) interval of 4.9 (2.8) years between biopsies, NAFL resolved in 11 patients (12.8%) and progressed to steatohepatitis in 36 patients (41.9%). Steatohepatitis resolved in 24 (28.6%) of the patients with borderline NASH and 61 (22.1%) of those with definite NASH. Fibrosis progression or regression by at least 1 stage occurred in 132 (30%) and 151 [34%] participants, respectively. Metabolic syndrome (20 [95%] vs 108 [72%]; P = .03), baseline NAS (mean [SD], 5.0 [1.4] vs 4.3 [1.6]; P = .005), and smaller reduction in NAS (-0.2 [2] vs -0.9 [2]; P < .001) were associated with progression to advanced (stage 3-4) fibrosis vs those without progression to stage 3 to 4 fibrosis. Fibrosis regression was associated with lower baseline insulin level (20 vs 33 µU/mL; P = .02) and decrease in all NAS components (steatosis grade -0.8 [0.1] vs -0.3 [0.9]; P < .001; lobular inflammation -0.5 [0.8] vs -0.2 [0.9]; P < .001; ballooning -0.7 [1.1] vs -0.1 [0.9]; P < .001). Only baseline aspartate aminotransferase (AST) levels were associated with fibrosis regression vs no change and progression vs no change on multivariable regression: baseline AST (regression: conditional odds ratio [cOR], 0.6 per 10 U/L AST; 95% CI, 0.4-0.7; P < .001; progression: cOR, 1.3; 95% CI, 1.1-1.5; P = .002). Changes in the AST level, alanine aminotransferase (ALT) level, and NAS were also associated with fibrosis regression and progression (ΔAST level: regression, cOR, 0.9; 95% CI, 0.6-1.2; P = .47; progression, cOR, 1.3; 95% CI, 1.0-1.6; P = .02; ΔALT level: regression, cOR, 0.7 per 10 U/L AST; 95% CI, 0.5-0.9; P = .002; progression, cOR, 1.0 per 10 U/L AST; 95% CI, 0.9-1.2; P = .93; ΔNAS: regression, cOR, 0.7; 95% CI, 0.6-0.9; P = .001; progression, cOR, 1.3; 95% CI, 1.1-1.5; P = .01). Conclusions and Relevance: Improvement or worsening of disease activity may be associated with fibrosis regression or progression, respectively, in NAFLD.


Assuntos
Progressão da Doença , Cirrose Hepática/fisiopatologia , Hepatopatia Gordurosa não Alcoólica/fisiopatologia , Centros Médicos Acadêmicos , Adulto , Aspartato Aminotransferases/análise , Estudos de Coortes , Feminino , Humanos , Fígado/patologia , Masculino , Pessoa de Meia-Idade , Fatores de Risco , Estados Unidos , Aumento de Peso
7.
Gastroenterology ; 157(4): 1109-1122, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31255652

RESUMO

BACKGROUND & AIMS: The intestinal microbiome might affect the development and severity of nonalcoholic fatty liver disease (NAFLD). We analyzed microbiomes of children with and without NAFLD. METHODS: We performed a prospective, observational, cross-sectional study of 87 children (age range, 8-17 years) with biopsy-proven NAFLD and 37 children with obesity without NAFLD (controls). Fecal samples were collected and microbiome composition and functions were assessed using 16S ribosomal RNA amplicon sequencing and metagenomic shotgun sequencing. Microbial taxa were identified using zero-inflated negative binomial modeling. Genes contributing to bacterial pathways were identified using gene set enrichment analysis. RESULTS: Fecal microbiomes of children with NAFLD had lower α-diversity than those of control children (3.32 vs 3.52, P = .016). Fecal microbiomes from children with nonalcoholic steatohepatitis (NASH) had the lowest α-diversity (control, 3.52; NAFLD, 3.36; borderline NASH, 3.37; NASH, 2.97; P = .001). High abundance of Prevotella copri was associated with more severe fibrosis (P = .036). Genes for lipopolysaccharide biosynthesis were enriched in microbiomes from children with NASH (P < .001). Classification and regression tree model with level of alanine aminotransferase and relative abundance of the lipopolysaccharide pathway gene encoding 3-deoxy-d-manno-octulosonate 8-phosphate-phosphatase identified patients with NASH with an area under the receiver operating characteristic curve value of 0.92. Genes involved in flagellar assembly were enriched in the fecal microbiomes of patients with moderate to severe fibrosis (P < .001). Classification and regression tree models based on level of alanine aminotransferase and abundance of genes encoding flagellar biosynthesis protein had good accuracy for identifying case children with moderate to severe fibrosis (area under the receiver operating characteristic curve, 0.87). CONCLUSIONS: In an analysis of fecal microbiomes of children with NAFLD, we associated NAFLD and NASH with intestinal dysbiosis. NAFLD and its severity were associated with greater abundance of genes encoding inflammatory bacterial products. Alterations to the intestinal microbiome might contribute to the pathogenesis of NAFLD and be used as markers of disease or severity.


Assuntos
Bactérias/genética , DNA Bacteriano/genética , Microbioma Gastrointestinal , Intestinos/microbiologia , Cirrose Hepática/microbiologia , Hepatopatia Gordurosa não Alcoólica/microbiologia , RNA Ribossômico 16S/genética , Adolescente , Bactérias/classificação , Bactérias/patogenicidade , Estudos de Casos e Controles , Criança , Estudos Transversais , Disbiose , Fezes/microbiologia , Feminino , Interações Hospedeiro-Patógeno , Humanos , Cirrose Hepática/diagnóstico , Cirrose Hepática/etiologia , Masculino , Metagenoma , Hepatopatia Gordurosa não Alcoólica/complicações , Hepatopatia Gordurosa não Alcoólica/diagnóstico , Estudos Prospectivos , Ribotipagem , Índice de Gravidade de Doença
8.
J Pediatr ; 198: 76-83.e2, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29661561

RESUMO

OBJECTIVE: To determine the percentage of children with nonalcoholic fatty liver disease (NAFLD) in whom intervention for low-density lipoprotein cholesterol or triglycerides was indicated based on National Heart, Lung, and Blood Institute guidelines. STUDY DESIGN: This multicenter, longitudinal cohort study included children with NAFLD enrolled in the National Institute of Diabetes and Digestive and Kidney Diseases Nonalcoholic Steatohepatitis Clinical Research Network. Fasting lipid profiles were obtained at diagnosis. Standardized dietary recommendations were provided. After 1 year, lipid profiles were repeated and interpreted according to National Heart, Lung, and Blood Institute Expert Panel on Integrated Guidelines for Cardiovascular Health and Risk Reduction. Main outcomes were meeting criteria for clinically actionable dyslipidemia at baseline, and either achieving lipid goal at follow-up or meeting criteria for ongoing intervention. RESULTS: There were 585 participants, with a mean age of 12.8 years. The prevalence of children warranting intervention for low-density lipoprotein cholesterol at baseline was 14%. After 1 year of recommended dietary changes, 51% achieved goal low-density lipoprotein cholesterol, 27% qualified for enhanced dietary and lifestyle modifications, and 22% met criteria for pharmacologic intervention. Elevated triglycerides were more prevalent, with 51% meeting criteria for intervention. At 1 year, 25% achieved goal triglycerides with diet and lifestyle changes, 38% met criteria for advanced dietary modifications, and 37% qualified for antihyperlipidemic medications. CONCLUSIONS: More than one-half of children with NAFLD met intervention thresholds for dyslipidemia. Based on the burden of clinically relevant dyslipidemia, lipid screening in children with NAFLD is warranted. Clinicians caring for children with NAFLD should be familiar with lipid management.


Assuntos
Hipercolesterolemia/diagnóstico , Hipercolesterolemia/epidemiologia , Hipertrigliceridemia/diagnóstico , Hipertrigliceridemia/epidemiologia , Hepatopatia Gordurosa não Alcoólica/complicações , Criança , LDL-Colesterol/sangue , Dieta , Feminino , Humanos , Hipercolesterolemia/terapia , Hipertrigliceridemia/terapia , Estilo de Vida , Estudos Longitudinais , Masculino , Hepatopatia Gordurosa não Alcoólica/sangue , Triglicerídeos/sangue
9.
Clin Gastroenterol Hepatol ; 16(9): 1511-1520.e5, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29378307

RESUMO

BACKGROUND & AIMS: Cross-sectional studies of patients with nonalcoholic fatty liver disease (NAFLD) have reported a lower prevalence of severe disease among modest drinkers compared with nondrinkers. We collected data from adult participants in the Nonalcoholic Steatohepatitis (NASH) Clinical Research Network to evaluate the longitudinal association between modest use of alcohol and histology findings in patients with NAFLD, using paired liver biopsies collected more than 1 year apart. METHODS: We studied NASH Clinical Research Network participants 21 years or older, not receiving pharmacologic therapy, from whom 2 or more liver biopsies and data on alcohol use within 2 years of the initial biopsy were available. Alcohol consumption was evaluated at study entry using the Alcohol Use Disorders Identification Test and Skinner Lifetime Drinking History questionnaires. At each follow-up visit participants were asked about alcohol use frequency, number of drinks on a typical day, and frequency of heavy drinking. The association between baseline drinking status and changes in fibrosis stage, NASH histology, and the NAFLD Activity Score and its individual components were evaluated by analysis of covariance. The association between change in drinking status and change in histology was evaluated using adjusted logistic regression. RESULTS: Of 285 participants (82% white, 70% female, mean age, 47 y) meeting entry criteria, 168 (59%) were modest alcohol users (≤2 drinks/d) and the remaining 117 were abstinent. At baseline, a higher proportion of modest alcohol users were white (86% vs 76% nonwhite) (P = .04) and a lower proportion of modest alcohol users were diagnosed with definite NASH (57% vs 74% without NASH; P = .01). During a mean follow-up period of 47 months between biopsies, nondrinkers had a greater mean reduction in steatosis grade (reduction, 0.49) than modest drinkers (reduction, 0.30; P = .04) and a greater reduction in mean level of aspartate transaminase (reduction, 7 U/L vs an increase of 2 U/L in modest drinkers; P = .04). Modest drinkers had significantly lower odds of NASH resolution compared with nondrinkers (adjusted odds ratio, 0.32; 95% CI, 0.11-0.92; P = .04) on adjusted analysis. CONCLUSIONS: In a longitudinal analysis of liver biopsies from patients with NAFLD not receiving pharmacologic therapy, modest alcohol use was associated with less improvement in steatosis and level of aspartate transaminase, as well as lower odds of NASH resolution, compared with no use of alcohol.


Assuntos
Consumo de Bebidas Alcoólicas/efeitos adversos , Hepatopatia Gordurosa não Alcoólica/patologia , Remissão Espontânea , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Histocitoquímica , Humanos , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Inquéritos e Questionários , Adulto Jovem
10.
Clin Gastroenterol Hepatol ; 16(3): 438-446.e1, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-28286193

RESUMO

BACKGROUND & AIMS: Focal zone 1 steatosis, although rare in adults with nonalcoholic fatty liver disease (NAFLD), does occur in children with NAFLD. We investigated whether focal zone 1 steatosis and focal zone 3 steatosis are distinct subphenotypes of pediatric NAFLD. We aimed to determine associations between the zonality of steatosis and demographic, clinical, and histologic features in children with NAFLD. METHODS: We performed a cross-sectional study of baseline data from 813 children (age <18 years; mean age, 12.8 ± 2.7 years). The subjects had biopsy-proven NAFLD and were enrolled in the Nonalcoholic Steatohepatitis Clinical Research Network. Liver histology was reviewed using the Nonalcoholic Steatohepatitis Clinical Research Network scoring system. RESULTS: Zone 1 steatosis was present in 18% of children with NAFLD (n = 146) and zone 3 steatosis was present in 32% (n = 244). Children with zone 1 steatosis were significantly younger (10 vs 14 years; P < .001) and a significantly higher proportion had any fibrosis (81% vs 51%; P < .001) or advanced fibrosis (13% vs 5%; P < .001) compared with children with zone 3 steatosis. In contrast, children with zone 3 steatosis were significantly more likely to have steatohepatitis (30% vs 6% in children with zone 1 steatosis; P < .001). CONCLUSIONS: Children with zone 1 or zone 3 distribution of steatosis have an important subphenotype of pediatric NAFLD. Children with zone 1 steatosis are more likely to have advanced fibrosis and children with zone 3 steatosis are more likely to have steatohepatitis. To achieve a comprehensive understanding of pediatric NAFLD, studies of pathophysiology, natural history, and response to treatment should account for the zonality of steatosis.


Assuntos
Fígado Gorduroso/etiologia , Fígado Gorduroso/patologia , Cirrose Hepática/complicações , Cirrose Hepática/patologia , Hepatopatia Gordurosa não Alcoólica/complicações , Adolescente , Biópsia , Criança , Estudos Transversais , Feminino , Hepatite C , Histocitoquímica , Humanos , Masculino
11.
Hum Pathol ; 52: 28-37, 2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-26980020

RESUMO

The significance of the quantity of acidophil bodies (AB) in nonalcoholic steatohepatitis (NASH) is not certain. We quantified AB in liver biopsies and examined the association with the diagnosis of NASH and other histologic features. We reviewed 157 liver biopsies from the NASH Clinical Research Network Database collected in 2006. One hundred twenty-seven biopsies were from adult patients. Diagnoses were 94 definite NASH, 40 borderline NASH, and 23 definitely not NASH. The total length and average width of the core biopsies were measured, and the biopsy areas were calculated (mm(2)). Total AB were counted, and mean AB count per mm(2) was calculated (AB/mm(2)) to derive acidophil body index (ABI). ABI was 0.04 (±0.08) in definite NASH and 0.02 (±0.05) in borderline/definitely not NASH groups combined (P = .02) in all 157 biopsies; similar findings were present in the 127 adult-only biopsies (0.04 ± 0.05 and 0.02 ± 0.05, respectively; P = .05). In all 157 biopsies, increased ABI was associated with greater lobular inflammation (P = .01) and many ballooned hepatocytes (P = .048). There was a positive relationship between ABI and high nonalcoholic fatty liver disease activity scores, but this association was not statistically significant. There was no association between ABI and steatosis or fibrosis stage either in the entire cohorts or in the subset of adult patients. In conclusion, the density of AB is associated with lobular inflammation, ballooned hepatocytes, and the diagnosis of NASH in adult and pediatric liver biopsies, suggesting the implication of the apoptotic pathway in NASH-associated liver cell injury.


Assuntos
Apoptose , Vesículas Extracelulares/patologia , Hepatócitos/patologia , Cirrose Hepática/patologia , Fígado/patologia , Hepatopatia Gordurosa não Alcoólica/patologia , Adolescente , Adulto , Biópsia com Agulha de Grande Calibre , Tamanho Celular , Criança , Bases de Dados Factuais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Prognóstico , Índice de Gravidade de Doença , Estados Unidos , Adulto Jovem
12.
J Pediatr Gastroenterol Nutr ; 57(5): 627-33, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-24177784

RESUMO

AIMS: Fish and ω-3 fatty acids are reported to be beneficial in pediatric nonalcoholic fatty liver disease (NAFLD), but no studies have assessed their relation to histological severity. The objectives of this study were to evaluate the dietary intake of fish and ω-3 fatty acids in children with biopsy-proven NAFLD, and examine their association with serological and histological indicators of disease. METHODS: This was a cross-sectional analysis of 223 children (6-18 years) who participated in the Treatment of Nonalcoholic Fatty Liver Disease in Children trial or the NAFLD Database study conducted by the Nonalcoholic Steatohepatitis Clinical Research Network. The distribution of fish and ω-3 fatty acid intake was determined from responses to the Block Brief 2000 Food Frequency Questionnaire, and analyzed for associations with serum alanine aminotransferase, histological features of fatty liver disease, and diagnosis of steatohepatitis after adjusting for demographic, anthropometric, and dietary variables. RESULTS: The minority of subjects consumed the recommended 8 ounces of fish per week (22/223 [10%]) and 200 mg of long-chain ω-3 fatty acids per day (12/223 [5%]). Lack of fish and long-chain ω-3 fatty acid intake was associated with greater portal (P = 0.03 and P = 0.10, respectively) and lobular inflammation (P = 0.09 and P = 0.004, respectively) after controlling for potential confounders. CONCLUSIONS: Fish and ω-3 fatty acid intake was insufficient in children with NAFLD, which may increase susceptibility to hepatic inflammation. Patients with pediatric NAFLD should be encouraged to consume the recommended amount of fish per week.


Assuntos
Fenômenos Fisiológicos da Nutrição do Adolescente , Fenômenos Fisiológicos da Nutrição Infantil , Dieta/efeitos adversos , Ácidos Graxos Ômega-3/administração & dosagem , Fígado Gorduroso/etiologia , Peixes , Alimentos Marinhos , Adolescente , Comportamento do Adolescente , Animais , Criança , Comportamento Infantil , Estudos Transversais , Suscetibilidade a Doenças , Ácidos Graxos Ômega-3/análise , Fígado Gorduroso/metabolismo , Fígado Gorduroso/patologia , Fígado Gorduroso/fisiopatologia , Feminino , Promoção da Saúde , Humanos , Fígado/imunologia , Fígado/metabolismo , Fígado/patologia , Fígado/fisiopatologia , Masculino , Hepatopatia Gordurosa não Alcoólica , Política Nutricional , Cooperação do Paciente , Alimentos Marinhos/análise , Índice de Gravidade de Doença , Estados Unidos
13.
Hepatology ; 55(1): 77-85, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-21953442

RESUMO

UNLABELLED: Serum ferritin (SF) levels are commonly elevated in patients with nonalcoholic fatty liver disease (NAFLD) because of systemic inflammation, increased iron stores, or both. The aim of this study was to examine the relationship between elevated SF and NAFLD severity. Demographic, clinical, histologic, laboratory, and anthropometric data were analyzed in 628 adult patients with NAFLD (age, ≥ 18 years) with biopsy-proven NAFLD and an SF measurement within 6 months of their liver biopsy. A threshold SF >1.5 × upper limit of normal (ULN) (i.e., >300 ng/mL in women and >450 ng/mL in men) was significantly associated with male sex, elevated serum alanine aminotransferase, aspartate aminotransferase, iron, transferrin-iron saturation, iron stain grade, and decreased platelets (P < 0.01). Histologic features of NAFLD were more severe among patients with SF >1.5 × ULN, including steatosis, fibrosis, hepatocellular ballooning, and diagnosis of NASH (P < 0.026). On multiple regression analysis, SF >1.5 × ULN was independently associated with advanced hepatic fibrosis (odds ratio [OR], 1.66; 95% confidence interval [CI], 1.05-2.62; P = 0.028) and increased NAFLD Activity Score (NAS) (OR, 1.99; 95% CI, 1.06-3.75; P = 0.033). CONCLUSIONS: A SF >1.5 × ULN is associated with hepatic iron deposition, a diagnosis of NASH, and worsened histologic activity and is an independent predictor of advanced hepatic fibrosis among patients with NAFLD. Furthermore, elevated SF is independently associated with higher NAS, even among patients without hepatic iron deposition. We conclude that SF is useful to identify NAFLD patients at risk for NASH and advanced fibrosis.


Assuntos
Fígado Gorduroso/sangue , Fígado Gorduroso/patologia , Ferritinas/sangue , Cirrose Hepática/sangue , Cirrose Hepática/patologia , Índice de Gravidade de Doença , Adulto , Biomarcadores/sangue , Biópsia , Fígado Gorduroso/epidemiologia , Feminino , Humanos , Ferro/metabolismo , Fígado/metabolismo , Fígado/patologia , Cirrose Hepática/epidemiologia , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Hepatopatia Gordurosa não Alcoólica , Valor Preditivo dos Testes , Fatores de Risco
14.
Hepatology ; 55(3): 769-80, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21987488

RESUMO

UNLABELLED: Nonalcoholic fatty liver disease (NAFLD) is the most common liver disorder in the United States; however, few data are available about racial and ethnic variation. We investigated relationships between ethnicity, NAFLD severity, metabolic derangements, and sociodemographic characteristics in a well-characterized cohort of adults with biopsy-proven NAFLD. Data were analyzed from 1,026 adults (≥18 years) in the Nonalcoholic Steatohepatitis Clinical Research Network (NASH CRN) from 2004 to 2008, for whom liver histology data were available within 6 months of enrollment. Associations between ethnicity (i.e., Latino versus non-Latino white) and NAFLD severity (i.e., NASH versus non-NASH histology and mild versus advanced fibrosis) were explored with multiple logistic regression analysis. We also investigated effect modification of ethnicity on metabolic derangements for NAFLD severity. Within the NASH CRN, 77% (N = 785) were non-Latino white and 12% (N = 118) were Latino. Sixty-one percent (N = 628) had NASH histology and 28% (N = 291) had advanced fibrosis. Latinos with NASH were younger, performed less physical activity, and had higher carbohydrate intake, compared to non-Latino whites with NASH. Gender, diabetes, hypertension, hypertriglyceridemia, aspartate aminotransferase (AST), platelets, and the homeostasis model assessment of insulin resistance (HOMA-IR) were significantly associated with NASH. Age, gender, AST, alanine aminotransferase, alkaline phosphatase, platelets, total cholesterol, hypertension, and HOMA-IR, but not ethnicity, were significantly associated with advanced fibrosis. The effect of HOMA-IR on the risk of NASH was modified by ethnicity: HOMA-IR was not a significant risk factor for NASH among Latinos (odds ratio [OR] = 0.93; 95% confidence interval [CI]: 0.85-1.02), but was significant among non-Latino whites (OR, 1.06; 95% CI: 1.01-1.11). CONCLUSION: Metabolic risk factors and sociodemographic characteristics associated with NASH differ by ethnicity. Additional insights into NASH pathogenesis may come from further studies focused on understanding ethnic differences in this disease.


Assuntos
Fígado Gorduroso/etnologia , Fígado Gorduroso/epidemiologia , Hispânico ou Latino , Índice de Gravidade de Doença , População Branca , Adulto , Biópsia , Feminino , Humanos , Fígado/patologia , Cirrose Hepática/epidemiologia , Cirrose Hepática/etnologia , Cirrose Hepática/patologia , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Hepatopatia Gordurosa não Alcoólica , Estudos Retrospectivos , Fatores de Risco , Fatores Socioeconômicos , Estados Unidos/epidemiologia
15.
Hum Pathol ; 43(6): 790-800, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22036053

RESUMO

Nonalcoholic fatty liver disease is a global health dilemma. The gold standard for diagnosis is liver biopsy. Ballooned hepatocytes are histologic manifestations of hepatocellular injury and are characteristic of steatohepatitis, the more severe form of nonalcoholic fatty liver disease. Definitive histologic identification of ballooned hepatocytes on routine stains, however, can be difficult. Immunohistochemical evidence for loss of the normal hepatocytic keratin 8/18 can serve as an objective marker of ballooned hepatocytes. We sought to explore the utility of a keratin 8/18 plus ubiquitin double immunohistochemical stain for the histologic evaluation of adult nonalcoholic fatty liver disease. Double immunohistochemical staining for keratin 8/18 and ubiquitin was analyzed using 40 adult human nonalcoholic fatty liver disease core liver biopsies. Ballooned hepatocytes lack keratin 8/18 staining as previously shown by others, but normal-size hepatocytes with keratin loss are approximately 5 times greater in number than keratin-negative ballooned hepatocytes. Keratin-negative ballooned hepatocytes, normal-size hepatocytes with keratin loss, and ubiquitin deposits show a zonal distribution, are positively associated with each other, and are frequently found adjacent to or intermixed with fibrous matrix. All 3 lesions correlate with fibrosis stage and the hematoxylin and eosin diagnosis of steatohepatitis (all P < .05). Compared with hematoxylin and eosin staining, immunohistochemical staining improves the receiver operating characteristics curve for advanced fibrosis (0.77 versus 0.83, 0.89, and 0.89 for keratin-negative ballooned hepatocytes, normal-size hepatocytes with keratin loss, and ubiquitin, respectively) because immunohistochemistry is more sensitive and specific for fibrogenic hepatocellular injury than hematoxylin and eosin staining. Keratin 8/18 plus ubiquitin double immunohistochemical stain improves detection of hepatocyte injury in nonalcoholic fatty liver disease. Thus, it may help differentiate nonalcoholic steatohepatitis from nonalcoholic fatty liver.


Assuntos
Biomarcadores/análise , Fígado Gorduroso/diagnóstico , Hepatócitos/patologia , Queratina-18/análise , Queratina-8/análise , Ubiquitina/análise , Fígado Gorduroso/metabolismo , Feminino , Hepatócitos/química , Humanos , Imuno-Histoquímica , Masculino , Pessoa de Meia-Idade , Hepatopatia Gordurosa não Alcoólica
16.
J Pediatr Gastroenterol Nutr ; 54(1): 90-6, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22197855

RESUMO

OBJECTIVES: Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in children in the United States. Although changes in diet are often recommended to improve NAFLD, little is known regarding the influence of diet on histologic features of the disease. SUBJECTS AND METHODS: This was a prospective, cross-sectional registry-based study. Children (n = 149) enrolled in the multicenter nonalcoholic steatohepatitis (NASH) Clinical Research Network had demographic, anthropometric, clinical, laboratory, and histology data obtained, including the Block Brief Food Questionnaire. Subjects were grouped by presence or absence of steatohepatitis and grades of histologic features according to NASH Clinical Research Network criteria. RESULTS: No significant differences were found between children with steatosis compared with steatohepatitis for fraction of energy from fat, carbohydrates, and protein. Sugar-sweetened beverage consumption was low and did not correlate with histologic features, although uric acid, a surrogate marker for fructose intake, was significantly increased in those with definite NASH (P = 0.008). For all groups, vitamin E consumption was insufficient compared with the recommended daily allowance. Median consumption of vitamin E was lower in children with higher grade of steatosis (8.4 vs 6.1 vs 6.9 for grades I, II, and III, respectively, P = 0.05). Those consuming less vitamin C had increased ballooning degeneration (P = 0.05). CONCLUSIONS: Children with NAFLD have a diet that is insufficient in vitamin E and this may contribute to the pathophysiology of NAFLD. In children with NAFLD, reported sugar-sweetened beverage consumption is low; however, uric acid, which may reflect total fructose consumption, was significantly associated with NASH and should be further evaluated.


Assuntos
Dieta , Fígado Gorduroso/etiologia , Fígado/patologia , Ácido Úrico/sangue , Deficiência de Vitamina E/complicações , Vitamina E/administração & dosagem , Adolescente , Ácido Ascórbico/administração & dosagem , Criança , Estudos Transversais , Sacarose Alimentar/administração & dosagem , Ingestão de Energia , Fígado Gorduroso/sangue , Fígado Gorduroso/patologia , Feminino , Frutose/administração & dosagem , Humanos , Masculino , Hepatopatia Gordurosa não Alcoólica , Avaliação Nutricional , Estudos Prospectivos , Inquéritos e Questionários , Vitaminas/administração & dosagem
17.
Am J Surg Pathol ; 35(9): 1400-4, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21836480

RESUMO

Correct classification of nonalcoholic steatohepatitis (NASH) liver biopsies is of critical importance and relies on correct orientation to microscopic liver architecture. Centrizonal arteries can cause central zones to be mistaken for portal tracts, especially in the setting of centrizonal ductular reaction, and result in either missed diagnosis or inaccurate staging of NASH. A total of 100 randomly selected biopsies from NASH Clinical Research Network participants (February 2005 to August 2006, fibrosis stage >1a) were evaluated for arteries and CD34-positive microvessels in the centrizonal region. Prevalence of both centrizonal arteries and CD34-positive microvessels was graded as 0 (none in central zones), 1 (1 to 2 central zones with vessels), 2 (<50% of central zones with vessels), or 3 (≥50% of central zones with vessels). Centrizonal arteries and CD34-positive microvessels were present in 40 and 100 cases (40% and 100%), respectively. Arteries and CD34-positive microvessels were more commonly found in central zones in biopsies with greater degrees of fibrosis (62% with arteries in stage 3 to 4 versus 21% in stage 1 to 2 and 70% with microvessels in stage 3 to 4 versus 25% in stage 1 to 2), with increased prevalence of both centrizonal arteries and CD34-positive microvessels correlating directly with fibrosis stage (P<0.001). Ductular reaction was a common finding (55%) in patients with central zone arteries. The presence of centrizonal arteries must be recognized to allow for correct orientation to liver architecture in NASH and, together with the finding of increased CD34-positive microvessel formation in higher-stage fibrosis, suggests a possible association between neoangiogenesis and NASH progression to cirrhosis.


Assuntos
Fígado Gorduroso/patologia , Fígado/irrigação sanguínea , Microvasos/patologia , Adolescente , Adulto , Antígenos CD34/análise , Arteríolas/patologia , Ductos Biliares Intra-Hepáticos/patologia , Biópsia , Distribuição de Qui-Quadrado , Progressão da Doença , Fígado Gorduroso/complicações , Fígado Gorduroso/fisiopatologia , Humanos , Imuno-Histoquímica , Cirrose Hepática/etiologia , Cirrose Hepática/patologia , Microvasos/imunologia , Microvasos/fisiopatologia , Pessoa de Meia-Idade , Neovascularização Fisiológica , Hepatopatia Gordurosa não Alcoólica , Valor Preditivo dos Testes , Índice de Gravidade de Doença , Adulto Jovem
18.
Hepatology ; 53(3): 810-20, 2011 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21319198

RESUMO

UNLABELLED: The diagnosis of nonalcoholic steatohepatitis (NASH) is defined by the presence and pattern of specific histological abnormalities on liver biopsy. A separate system of scoring the features of nonalcoholic fatty liver disease (NAFLD) called the NAFLD Activity Score (NAS) was developed as a tool to measure changes in NAFLD during therapeutic trials. However, some studies have used threshold values of the NAS, specifically NAS ≥5, as a surrogate for the histologic diagnosis of NASH. To evaluate whether this unintended use of the NAS is valid, biopsy and clinical data from the 976 adults in NASH Clinical Research Network (CRN) studies were reviewed. Biopsies were evaluated centrally by the NASH CRN Pathology Committee. Definite steatohepatitis (SH) was diagnosed in 58.1%, borderline SH in 19.5% and "not SH" in 22%. The NAS was ≥5 in 50% and ≤4 in 49%; in this cohort only 75% of biopsies with definite SH had an NAS ≥5, whereas 28% of borderline SH and 7% of "not SH" biopsies had NAS ≥5. Of biopsies with an NAS ≥5, 86% had SH and 3% "not SH". NAS ≤4 did not indicate benign histology; 29% had SH and only 42% had "not SH." Higher values of the NAS were associated with higher levels of alanine aminotransferase and aspartate aminotransferase, whereas the diagnosis of SH was associated with features of the metabolic syndrome. CONCLUSION: The diagnosis of definite SH or the absence of SH based on evaluation of patterns as well as individual lesions on liver biopsies does not always correlate with threshold values of the semiquantitative NAS. Clinical trials and observational studies should take these different performance characteristics into account.


Assuntos
Fígado Gorduroso , Adolescente , Adulto , Idoso , Alanina Transaminase/sangue , Aspartato Aminotransferases/sangue , Biópsia , Fígado Gorduroso/diagnóstico , Fígado Gorduroso/patologia , Feminino , Humanos , Fígado/patologia , Masculino , Pessoa de Meia-Idade , Hepatopatia Gordurosa não Alcoólica , Estudos Prospectivos , Sensibilidade e Especificidade , Índice de Gravidade de Doença
19.
Mol Cell Endocrinol ; 332(1-2): 196-212, 2011 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-21075170

RESUMO

Aggresome formation, a cellular response to misfolded protein aggregates, is linked to cancer and neurodegenerative disorders. Previously we showed that Gag-v-ErbA (v-ErbA), a retroviral variant of the thyroid hormone receptor (TRα1), accumulates in and sequesters TRα1 into cytoplasmic foci. Here, we show that foci represent v-ErbA targeting to aggresomes. v-ErbA colocalizes with aggresomal markers, proteasomes, hsp70, HDAC6, and mitochondria. Foci have hallmark characteristics of aggresomes: formation is microtubule-dependent, accelerated by proteasome inhibitors, and they disrupt intermediate filaments. Proteasome-mediated degradation is critical for clearance of v-ErbA and T(3)-dependent TRα1 clearance. Our studies highlight v-ErbA's complex mode of action: the oncoprotein is highly mobile and trafficks between the nucleus, cytoplasm, and aggresome, carrying out distinct activities within each compartment. Dynamic trafficking to aggresomes contributes to the dominant negative activity of v-ErbA and may be enhanced by the viral Gag sequence. These studies provide insight into novel modes of oncogenesis across multiple cellular compartments.


Assuntos
Corpos de Inclusão/metabolismo , Proteínas Oncogênicas v-erbA/metabolismo , Alpharetrovirus/genética , Alpharetrovirus/metabolismo , Transporte Biológico , Biomarcadores/metabolismo , Dineínas/metabolismo , Eritroblastos/citologia , Eritroblastos/metabolismo , Eritroblastos/virologia , Produtos do Gene gag/genética , Produtos do Gene gag/metabolismo , Proteínas de Choque Térmico HSP70/metabolismo , Células HeLa , Desacetilase 6 de Histona , Histona Desacetilases/genética , Histona Desacetilases/metabolismo , Humanos , Filamentos Intermediários/metabolismo , Microtúbulos/metabolismo , Mitocôndrias/metabolismo , Proteínas Oncogênicas v-erbA/genética , Complexo de Endopeptidases do Proteassoma/metabolismo , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Vimentina/metabolismo
20.
Appl Environ Microbiol ; 76(15): 4950-9, 2010 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-20543045

RESUMO

Elevated atmospheric CO(2) can cause increased carbon fixation and altered foliar chemical composition in a variety of plants, which has the potential to impact forested headwater streams because they are detritus-based ecosystems that rely on leaf litter as their primary source of organic carbon. Fungi and bacteria play key roles in the entry of terrestrial carbon into aquatic food webs, as they decompose leaf litter and serve as a source of nutrition for invertebrate consumers. This study tested the hypothesis that changes in leaf chemistry caused by elevated atmospheric CO(2) would result in changes in the size and composition of microbial communities colonizing leaves in a woodland stream. Three tree species, Populus tremuloides, Salix alba, and Acer saccharum, were grown under ambient (360 ppm) or elevated (720 ppm) CO(2), and their leaves were incubated in a woodland stream. Elevated-CO(2) treatment resulted in significant increases in the phenolic and tannin contents and C/N ratios of leaves. Microbial effects, which occurred only for P. tremuloides leaves, included decreased fungal biomass and decreased bacterial counts. Analysis of fungal and bacterial communities on P. tremuloides leaves via terminal restriction fragment length polymorphism (T-RFLP) and clone library sequencing revealed that fungal community composition was mostly unchanged by the elevated-CO(2) treatment, whereas bacterial communities showed a significant shift in composition and a significant increase in diversity. Specific changes in bacterial communities included increased numbers of alphaproteobacterial and cytophaga-flavobacter-bacteroides (CFB) group sequences and decreased numbers of betaproteobacterial and firmicutes sequences, as well as a pronounced decrease in overall gram-positive bacterial sequences.


Assuntos
Bactérias/crescimento & desenvolvimento , Biodiversidade , Dióxido de Carbono/metabolismo , Fungos/crescimento & desenvolvimento , Folhas de Planta/microbiologia , Rios/microbiologia , Árvores/crescimento & desenvolvimento , Acer/crescimento & desenvolvimento , Bactérias/classificação , Bactérias/genética , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Fúngico/química , DNA Fúngico/genética , DNA Ribossômico/química , DNA Ribossômico/genética , DNA Espaçador Ribossômico/química , DNA Espaçador Ribossômico/genética , Fungos/classificação , Fungos/genética , Genes de RNAr , Dados de Sequência Molecular , Populus/crescimento & desenvolvimento , RNA Bacteriano/genética , RNA Ribossômico 16S/genética , Salix/crescimento & desenvolvimento , Análise de Sequência de DNA
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