Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 14 de 14
Filtrar
1.
Front Aging ; 4: 1150645, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37114095

RESUMO

Background: Hyperthyroidism is associated with lower lean body mass, as a result of catabolic actions of thyroid hormone. Therefore, higher thyroid hormone levels could be a factor in the development of sarcopenia and age associated functional decline. The relationship between thyroid hormone and muscle mass in ambulatory, euthyroid older adults is not known. Method: We used mixed-effects models to estimate the cross-sectional relationships (accounting for inter-person variability) between thyroid axis hormone measures and lower limb composition or sarcopenia at visits in the Baltimore Longitudinal Study of Aging (BLSA) at which DEXA scans were available and both thyrotropin (TSH) and free thyroxine (FT4) were in the reference range. Analyses were adjusted for levothyroxine use, age, race, sex, BMI, smoking, alcohol intake, cholesterol, and systolic blood pressure. Results: 1442 euthyroid participants (median age 68, 50% female, and 69% white) contributed to 5306 visits from 2003 to 2019. FT4 was negatively associated with lower limb lean mass (beta: 88.49; 95% Confidence Interval (CI): 122.78, -54.20; p < 0.001) and positively associated with sarcopenia (OR: 1.11%, 95% CI: 1.01, 1.22) in the whole cohort. Additionally, higher FT4 was associated with lower leg lean mass (beta: 66.79; 95% CI: 102.24, -31.33; p < 0.001) and sarcopenia (OR:1.09%, 95% CI:1.01, 1.18) in older adults, but not in younger adults alone. Conclusion: In euthyroid older adults, higher FT4 is associated with lower leg lean mass and higher odds of sarcopenia. Understanding the relationship between thyroid hormone and sarcopenia is needed to improve clinical decision-making and avoid functional decline from excess thyroid hormone use in older adults.

2.
JCO Oncol Pract ; 19(7): 395-402, 2023 07.
Artigo em Inglês | MEDLINE | ID: mdl-37023383

RESUMO

Immune checkpoint inhibitors (ICPis) have proven extremely efficacious in cancer therapy but also lead to a plethora of immune-related adverse events (irAEs). The endocrine irAEs are not only quite common but also may pose a challenge to the clinician while managing a patient with cancer treated with ICPis. The clinical features of endocrine dysfunction are usually nonspecific and may overlap with concurrent illnesses, underlying the importance of accurate hormone testing and efforts toward case-finding. The management of endocrine irAEs is unique in the focus being on hormone replacement rather than curtailing the autoimmune process. Although the management of thyroid irAEs appears straightforward, adrenal insufficiency and insulin-dependent diabetes can be life-threatening if not promptly recognized and treated. This clinical review synthesizes the studies to provide pearls and pitfalls in the evaluation and management of endocrine irAEs with specific reference to guidelines from oncologic societies.


Assuntos
Inibidores de Checkpoint Imunológico , Neoplasias , Humanos , Inibidores de Checkpoint Imunológico/uso terapêutico , Neoplasias/complicações , Neoplasias/tratamento farmacológico , Imunoterapia/efeitos adversos , Hormônios/uso terapêutico
3.
RMD Open ; 8(2)2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-36096522

RESUMO

OBJECTIVE: Patients with inflammatory arthritis (IA) associated with immune checkpoint inhibitor (ICI) treatment for cancer are typically seronegative for anti-cyclic citrullinated peptide (CCP) antibodies and rheumatoid factor, but little is known about the presence of other autoantibodies in this patient population. We investigated the prevalence and characteristics of anti-RA33 antibodies in patients with ICI-induced IA. METHODS: Anti-RA33 ELISAs were performed on sera from four groups of patients: 79 with ICI-induced IA, 52 with rheumatoid arthritis (RA), 35 treated with ICIs without IA during follow-up and 50 healthy controls. Anti-RA33 positivity and level, clinical and demographic data were compared across groups. RESULTS: Anti-RA33 antibodies were found in 9/79 (11.4%) patients with ICI-induced IA but in 0/35 patients treated with ICIs who did not develop IA (0%; p=0.04). Of the patients positive for anti-RA33, two had sera available from before ICI treatment; anti-RA33 antibodies were present in both pre-ICI treatments. In patients with RA, 7.7% were positive for anti-RA33 antibodies as were 2% of healthy controls. In ICI-induced IA, anti-RA33 antibodies were associated with anti-CCP antibodies (p=0.001). We found no statistically significant differences in other clinical characteristics in those with and without anti-RA33 antibodies. CONCLUSIONS: Anti-RA33 antibodies are present in a subset of patients with ICI-induced IA, absent in other ICI-treated patients and may be a biomarker for developing IA. Additional studies evaluating serial samples before and after ICI treatment will further establish the temporal relationship of these antibodies to IA development.


Assuntos
Artrite Reumatoide , Inibidores de Checkpoint Imunológico , Anticorpos Antiproteína Citrulinada , Autoanticorpos , Humanos , Fator Reumatoide
4.
J Clin Oncol ; 39(35): 3978-3992, 2021 12 10.
Artigo em Inglês | MEDLINE | ID: mdl-34724386

RESUMO

PURPOSE: To increase awareness, outline strategies, and offer guidance on the recommended management of immune-related adverse events (irAEs) in patients treated with chimeric antigen receptor (CAR) T-cell therapy. METHODS: A multidisciplinary panel of medical oncology, neurology, hematology, emergency medicine, nursing, trialists, and advocacy experts was convened to develop the guideline. Guideline development involved a systematic literature review and an informal consensus process. The systematic review focused on evidence published from 2017 to 2021. RESULTS: The systematic review identified 35 eligible publications. Because of the paucity of high-quality evidence, recommendations are based on expert consensus. RECOMMENDATIONS: The multidisciplinary team issued recommendations to aid in the recognition, workup, evaluation, and management of the most common CAR T-cell-related toxicities, including cytokine release syndrome, immune effector cell-associated neurotoxicity syndrome, B-cell aplasia, cytopenias, and infections. Management of short-term toxicities associated with CAR T cells begins with supportive care for most patients, but may require pharmacologic interventions for those without adequate response. Management of patients with prolonged or severe CAR T-cell-associated cytokine release syndrome includes treatment with tocilizumab with or without a corticosteroid. On the basis of the potential for rapid decline, patients with moderate to severe immune effector cell-associated neurotoxicity syndrome should be managed with corticosteroids and supportive care.Additional information is available at www.asco.org/supportive-care-guidelines.


Assuntos
Síndrome da Liberação de Citocina/terapia , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos/terapia , Imunoterapia Adotiva/efeitos adversos , Neoplasias/terapia , Guias de Prática Clínica como Assunto/normas , Síndrome da Liberação de Citocina/etiologia , Síndrome da Liberação de Citocina/patologia , Gerenciamento Clínico , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos/etiologia , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos/patologia , Humanos , Neoplasias/imunologia , Neoplasias/patologia , Prognóstico
5.
J Clin Oncol ; 39(36): 4073-4126, 2021 12 20.
Artigo em Inglês | MEDLINE | ID: mdl-34724392

RESUMO

PURPOSE: To increase awareness, outline strategies, and offer guidance on the recommended management of immune-related adverse events (irAEs) in patients treated with immune checkpoint inhibitor (ICPi) therapy. METHODS: A multidisciplinary panel of medical oncology, dermatology, gastroenterology, rheumatology, pulmonology, endocrinology, neurology, hematology, emergency medicine, nursing, trialists, and advocacy experts was convened to update the guideline. Guideline development involved a systematic literature review and an informal consensus process. The systematic review focused on evidence published from 2017 through 2021. RESULTS: A total of 175 studies met the eligibility criteria of the systematic review and were pertinent to the development of the recommendations. Because of the paucity of high-quality evidence, recommendations are based on expert consensus. RECOMMENDATIONS: Recommendations for specific organ system-based toxicity diagnosis and management are presented. While management varies according to the organ system affected, in general, ICPi therapy should be continued with close monitoring for grade 1 toxicities, except for some neurologic, hematologic, and cardiac toxicities. ICPi therapy may be suspended for most grade 2 toxicities, with consideration of resuming when symptoms revert ≤ grade 1. Corticosteroids may be administered. Grade 3 toxicities generally warrant suspension of ICPis and the initiation of high-dose corticosteroids. Corticosteroids should be tapered over the course of at least 4-6 weeks. Some refractory cases may require other immunosuppressive therapy. In general, permanent discontinuation of ICPis is recommended with grade 4 toxicities, except for endocrinopathies that have been controlled by hormone replacement. Additional information is available at www.asco.org/supportive-care-guidelines.


Assuntos
Inibidores de Checkpoint Imunológico/efeitos adversos , Humanos
6.
J Am Assoc Nurse Pract ; 33(8): 576-579, 2021 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-34397750

RESUMO

ABSTRACT: Cigarette smoking and poor air quality are the greatest risk factors for developing chronic obstructive pulmonary disease (COPD), but growing evidence indicates that genetic factors also affect predisposition to and clinical expression of disease. With the exception of α1-antitrypsin deficiency (AATD), a rare autosomal recessive disorder that is present in 1-3% of individuals with COPD, no single gene is associated with the development of obstructive lung disease. Instead, a complex interplay of genetic, epigenetic, and environmental factors is the basis for persistent inflammatory responses, accelerated cell aging, cell death, and fibrosis, leading to the clinical symptoms of COPD and different phenotypic presentations. In this brief review, we discuss current understanding of the genetics of COPD, pathogenetics of AATD, epigenetic influences on the development of obstructive lung disease, and how classifying COPD by phenotype can influence clinical treatment and patient outcomes.


Assuntos
Doença Pulmonar Obstrutiva Crônica , Deficiência de alfa 1-Antitripsina , Genótipo , Humanos , Fenótipo , Doença Pulmonar Obstrutiva Crônica/genética , Fatores de Risco , Deficiência de alfa 1-Antitripsina/genética
7.
Endocr Pract ; 26(7): 754-760, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33471644

RESUMO

OBJECTIVE: Clinical practice for differentiated thyroid cancer is moving towards lobectomy rather than total thyroidectomy in patients at low risk of recurrence. However, recurrence risk assessment depends on post-operative findings, while the surgical decision is based on preoperative factors. We determined the preoperative predictors of occult higher-risk pathology and rates of completion thyroidectomy among surgical candidates with nonbenign thyroid nodules 10 to 40 mm and no evidence of extrathyroidal extension or metastasis on preoperative evaluation. METHODS: Thyroid surgery cases at a single institution from 2005-2015 were reviewed to identify those meeting American Thyroid Association (ATA) criteria for lobectomy. ATA-based risk stratification from postoperative surgical pathology was compared to preoperative cytopathology, ultrasound, and clinical findings. RESULTS: Of 1,995 thyroid surgeries performed for nonbenign thyroid nodules 10 to 40 mm, 349 met ATA criteria for lobectomy. Occult high-risk features such as tall cell variant, gross extrathyroidal invasion, or vascular invasion were found in 36 cases (10.7%), while intraoperative lymphadenopathy led to surgical upstaging in 13 (3.7%). Intermediate risk features such as moderate lymphadenopathy or minimal extrathyroidal extension were present in an additional 44 cases. Occult risk features were present twice as often in Bethesda class 6 cases (35%) as in lower categories (12 to 17%). In multivariable analysis, Bethesda class and nodule size, but not age, race, sex, or ultrasound features, were significant predictors of occult higher-risk pathology. CONCLUSION: Most solitary thyroid nodules less than 4 cm and with cytology findings including atypia of undetermined significance through suspicious for papillary thyroid cancer would be sufficiently treated by lobectomy. ABBREVIATIONS: ATA = American Thyroid Association; CND = central neck dissection; DTC = differentiated thyroid cancer; ETE = extrathyroidal extension; FNA = fine needle aspiration; FTC/HCC = follicular thyroid carcinoma/Hurthle cell carcinoma; NIFTP = noninvasive follicular thyroid neoplasm with papillary-like nuclear features; OR = odds ratio; PTC = papillary thyroid cancer; US = ultrasound.


Assuntos
Adenocarcinoma Folicular , Carcinoma Hepatocelular , Neoplasias Hepáticas , Neoplasias da Glândula Tireoide , Nódulo da Glândula Tireoide , Humanos , Recidiva Local de Neoplasia , Estudos Retrospectivos , Fatores de Risco , Neoplasias da Glândula Tireoide/cirurgia , Nódulo da Glândula Tireoide/cirurgia
8.
J Clin Invest ; 129(10): 4305-4315, 2019 07 16.
Artigo em Inglês | MEDLINE | ID: mdl-31310589

RESUMO

BACKGROUND: Checkpoint inhibitor pneumonitis (CIP) is a highly morbid complication of immune checkpoint immunotherapy (ICI), one which precludes the continuation of ICI. Yet, the mechanistic underpinnings of CIP are unknown. METHODS: To better understand the mechanism of lung injury in CIP, we prospectively collected bronchoalveolar lavage (BAL) samples in ICI-treated patients with (n=12) and without CIP (n=6), prior to initiation of first-line therapy for CIP (high dose corticosteroids. We analyzed BAL immune cell populations using a combination of traditional multicolor flow cytometry gating, unsupervised clustering analysis and BAL supernatant cytokine measurements. RESULTS: We found increased BAL lymphocytosis, predominantly CD4+ T cells, in CIP. Specifically, we observed increased numbers of BAL central memory T-cells (Tcm), evidence of Type I polarization, and decreased expression of CTLA-4 and PD-1 in BAL Tregs, suggesting both activation of pro-inflammatory subsets and an attenuated suppressive phenotype. CIP BAL myeloid immune populations displayed enhanced expression of IL-1ß and decreased expression of counter-regulatory IL-1RA. We observed increased levels of T cell chemoattractants in the BAL supernatant, consistent with our pro-inflammatory, lymphocytic cellular landscape. CONCLUSION: We observe several immune cell subpopulations that are dysregulated in CIP, which may represent possible targets that could lead to therapeutics for this morbid immune related adverse event.


Assuntos
Linfócitos T CD4-Positivos/imunologia , Imunoterapia/efeitos adversos , Neoplasias/imunologia , Pneumonia/imunologia , Alvéolos Pulmonares/imunologia , Idoso , Lavagem Broncoalveolar , Linfócitos T CD4-Positivos/patologia , Citocinas/imunologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias/patologia , Neoplasias/terapia , Pneumonia/induzido quimicamente , Pneumonia/patologia , Receptor de Morte Celular Programada 1/imunologia , Estudos Prospectivos , Alvéolos Pulmonares/patologia
9.
J Clin Oncol ; 36(17): 1714-1768, 2018 06 10.
Artigo em Inglês | MEDLINE | ID: mdl-29442540

RESUMO

Purpose To increase awareness, outline strategies, and offer guidance on the recommended management of immune-related adverse events in patients treated with immune checkpoint inhibitor (ICPi) therapy. Methods A multidisciplinary, multi-organizational panel of experts in medical oncology, dermatology, gastroenterology, rheumatology, pulmonology, endocrinology, urology, neurology, hematology, emergency medicine, nursing, trialist, and advocacy was convened to develop the clinical practice guideline. Guideline development involved a systematic review of the literature and an informal consensus process. The systematic review focused on guidelines, systematic reviews and meta-analyses, randomized controlled trials, and case series published from 2000 through 2017. Results The systematic review identified 204 eligible publications. Much of the evidence consisted of systematic reviews of observational data, consensus guidelines, case series, and case reports. Due to the paucity of high-quality evidence on management of immune-related adverse events, recommendations are based on expert consensus. Recommendations Recommendations for specific organ system-based toxicity diagnosis and management are presented. While management varies according to organ system affected, in general, ICPi therapy should be continued with close monitoring for grade 1 toxicities, with the exception of some neurologic, hematologic, and cardiac toxicities. ICPi therapy may be suspended for most grade 2 toxicities, with consideration of resuming when symptoms revert to grade 1 or less. Corticosteroids may be administered. Grade 3 toxicities generally warrant suspension of ICPis and the initiation of high-dose corticosteroids (prednisone 1 to 2 mg/kg/d or methylprednisolone 1 to 2 mg/kg/d). Corticosteroids should be tapered over the course of at least 4 to 6 weeks. Some refractory cases may require infliximab or other immunosuppressive therapy. In general, permanent discontinuation of ICPis is recommended with grade 4 toxicities, with the exception of endocrinopathies that have been controlled by hormone replacement. Additional information is available at www.asco.org/supportive-care-guidelines and www.asco.org/guidelineswiki .


Assuntos
Antineoplásicos Imunológicos/administração & dosagem , Antineoplásicos Imunológicos/efeitos adversos , Neoplasias/tratamento farmacológico , Neoplasias/imunologia , Adulto , Anticorpos Monoclonais/administração & dosagem , Anticorpos Monoclonais/efeitos adversos , Antineoplásicos Imunológicos/imunologia , Antígeno B7-H1/antagonistas & inibidores , Antígeno B7-H1/imunologia , Antígeno CTLA-4/antagonistas & inibidores , Antígeno CTLA-4/imunologia , Humanos , Guias de Prática Clínica como Assunto , Receptor de Morte Celular Programada 1/antagonistas & inibidores , Receptor de Morte Celular Programada 1/imunologia
10.
J Gerontol A Biol Sci Med Sci ; 71(7): 961-7, 2016 07.
Artigo em Inglês | MEDLINE | ID: mdl-26791089

RESUMO

BACKGROUND: Emerging evidence suggests that mildly down-regulated thyroid function in older persons may protect and/or reflect maintained health. METHODS: Using observational data collected between January 2006 and March 2014 on a volunteer sample of 602 men and women aged 68-97 years with normal thyroid function participating in the Baltimore Longitudinal Study of Aging, this study examines the concurrent relationship between reported walking ability, usual and rapid gait speed, endurance walk performance, fatigability, and reported energy level with respect to free thyroxine (FT4) within the normal range (0.76-1.50ng/dL) as a continuous variable and categorized as low (lower quartile), medium (interquartile), or high (upper quartile). RESULTS: Adjusting for sex, age, race, height, weight, exercise and smoking, reported walking ability, usual and rapid gait speed, 400-m time, fatigability, and reported energy level were less favorable with increasing FT4 (p = .013 to <.001). In sex-strata, similar associations were observed except for walking ability in men and energy level in women. Categorical analyses revealed that persons with low FT4 exhibited better functional mobility, fitness, and reported energy than persons with intermediate or high levels (p < .05 for all). Persons with high-normal versus medium FT4 had slower usual and rapid gait speed (p < .05) only. CONCLUSION: Older adults with low-normal FT4 exhibit better mobility, fitness, and fatigue profiles. Mildly down-regulated thyroid function appears to align with better function in old age and may serve as a biomarker of healthy longevity.


Assuntos
Envelhecimento/fisiologia , Fadiga , Tiroxina/sangue , Caminhada/fisiologia , Idoso , Idoso de 80 Anos ou mais , Baltimore , Biomarcadores/sangue , Avaliação da Deficiência , Metabolismo Energético/fisiologia , Fadiga/diagnóstico , Fadiga/metabolismo , Fadiga/fisiopatologia , Feminino , Avaliação Geriátrica/métodos , Avaliação Geriátrica/estatística & dados numéricos , Humanos , Estudos Longitudinais , Masculino , Limitação da Mobilidade , Resistência Física/fisiologia , Estatística como Assunto
11.
Thyroid ; 23(9): 1151-8, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23517287

RESUMO

BACKGROUND: Interferon-alpha (IFNα)-induced thyroid dysfunction occurs in up to 20% of patients undergoing therapy for hepatitis C. The diversity of thyroid disease presentations suggests that several different pathological mechanisms are involved, such as autoimmunity and direct toxicity. Elucidating the relationships between risk factors and disease phenotype provides insight into the mechanisms of disease pathophysiology. METHODS: We studied 869 euthyroid patients from the ACHIEVE 2/3 trial, a randomized international clinical trial comparing pegylated-IFNα2a weekly or albumin-IFNα2b every 2 weeks for up to 24 weeks in patients with hepatitis C, genotype 2 or 3, from 136 centers. The study population was 60% male and 55% white. Serum thyrotropin (TSH) and free thyroxine were measured before therapy, monthly during treatment from week 8, and at 4- and 12-week follow-up visits. RESULTS: Overall, 181 (20.8%) participants had at least one abnormal TSH during the study. Low TSH occurred in 71 (8.2%), of whom 30 (3.5%) had a suppressed TSH below 0.1 mU/L. Hypothyroidism occurred in 53 patients (6.1%), with peak TSH above 10 mU/L in 12 patients (1.4%). Fifty-seven patients had a biphasic thyroiditis (6.6%), with extreme values for the nadir and/or peak TSH in all but one. Medical therapy was given to one thyrotoxic patient, four hypothyroid patients, and 26 biphasic thyroiditis patients. Multivariate logistic regression analysis demonstrated that biphasic thyroiditis is associated with being female and higher pretreatment serum TSH, whereas being Asian or a current smoker decreased the risk of thyroiditis. Hypo- and hyperthyroidism are most strongly predicted by the pretreatment TSH. CONCLUSIONS: Biphasic thyroiditis accounted for the majority (58%) of clinically relevant IFNα-induced thyroid dysfunction. We confirmed our recent findings in a related cohort that female sex is a risk factor for thyroiditis but not hypothyroidism. Further, in this large multiethnic study, the risk of thyroiditis is dramatically increased, specifically for white women. Smoking was found to be protective of thyroiditis. These results support closer monitoring of women and those with a serum TSH at the extremes of the normal range during therapy so that prompt intervention can mitigate the consequences of thyroid dysfunction associated with IFNα treatment.


Assuntos
Antivirais/efeitos adversos , Hepatite C/tratamento farmacológico , Hipotireoidismo/induzido quimicamente , Interferon-alfa/efeitos adversos , Polietilenoglicóis/efeitos adversos , Grupos Raciais , Albumina Sérica/efeitos adversos , Fumar/efeitos adversos , Tireoidite/induzido quimicamente , Tireotropina/sangue , Adulto , Ásia/epidemiologia , Biomarcadores/sangue , Distribuição de Qui-Quadrado , Europa (Continente)/epidemiologia , Feminino , Hepatite C/sangue , Hepatite C/diagnóstico , Hepatite C/etnologia , Humanos , Hipotireoidismo/sangue , Hipotireoidismo/etnologia , Hipotireoidismo/terapia , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , América do Norte/epidemiologia , Razão de Chances , Proteínas Recombinantes de Fusão/efeitos adversos , Proteínas Recombinantes/efeitos adversos , Fatores de Risco , Albumina Sérica Humana , Fatores Sexuais , América do Sul/epidemiologia , Tireoidite/sangue , Tireoidite/etnologia , Tireoidite/terapia , Tiroxina/sangue , Fatores de Tempo , Resultado do Tratamento
12.
Proc Natl Acad Sci U S A ; 106(11): 4266-71, 2009 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-19255421

RESUMO

Dioxin is an extremely potent carcinogen. In highly exposed people, the most commonly observed toxicity is chloracne, a pathological response of the skin. Most of the effects of dioxin are attributed to its activation of the aryl hydrocarbon receptor (AHR), a transcription factor that binds to the Ah receptor nuclear translocator (ARNT) to regulate the transcription of numerous genes, including CYP1A1 and CYP1B1. In cultures of normal human epidermal keratinocytes dioxin accelerates cell differentiation, as measured by the formation of cornified envelopes. We show that this acceleration is mediated by the AHR; also, that dioxin increases the expression of several genes known to be regulated by ARNT, which have critical roles in the cornification and epidermal barrier function of the skin. Importantly, we demonstrate that all of these responses are opposed by ligand-activation of the EGF receptor (R), an important regulator of keratinocyte cell fate. In the CYP1A1 enhancer, EGFR activation prevents recruitment of the p300 coactivator, although not affecting the binding of the AHR or ARNT. The total cellular level of p300 protein does not decrease, and overexpression of p300 relieves EGFR-mediated repression of transcription, indicating that p300 is a critical target for the repression of the AHR complex by EGFR signaling. These results provide a mechanism by which 2,3,7,8-tetrachlorodibenzo-p-dioxin is able to disrupt epidermal homeostasis and identify EGFR signaling as a regulator of the AHR. This signaling may modulate the incidence and severity of chloracne and be of therapeutic relevance to human poisonings by dioxin.


Assuntos
Diferenciação Celular , Células Epidérmicas , Receptores ErbB/fisiologia , Queratinócitos/citologia , Receptores de Hidrocarboneto Arílico/antagonistas & inibidores , Transcrição Gênica , Dioxinas/efeitos adversos , Epiderme/efeitos dos fármacos , Receptores ErbB/metabolismo , Homeostase/efeitos dos fármacos , Humanos , Receptores de Hidrocarboneto Arílico/fisiologia , Transdução de Sinais
13.
Pharmacogenet Genomics ; 15(3): 183-8, 2005 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-15861043

RESUMO

OBJECTIVES: Coumarins are naturally occurring chemicals with potential as chemopreventive agents, several with known action on the cytochrome P450 1A family. We examined whether cytochrome P450 1B1 (CYP1B1) was inhibited by coumarins, whether such inhibition was competitive, and whether inhibition varied between common polymorphic variants of this enzyme. METHODS: We tested the inhibition properties of four coumarins, bergamottin, isopimpinellin, isoimperatorin, and imperatorin in an assay for oxidation of (-)benzo[a]pyrene-7R-trans-7,8-dihyrodiol (B[a]P-7,8-diol) by CYP1B1 using yeast-microsome expressed enzymes. These assays were performed with wild-type enzyme and five single-amino acid polymorphic variants. RESULTS: All four coumarins are competitive inhibitors of CYP1B1, with Ki values equal to 587, 11, 6 and 1 muM respectively. Inhibition parameters were consistent between five haplotypes of CYP1B1, three representing common haplotypes in Asians, African-Americans and European-Americans, and two with baseline kinetic parameters previously shown to be potentially different from wild-type. CONCLUSIONS: Coumarins are capable of inhibiting carcinogen activation by CYP1B1 with varying potencies, and their efficacy as chemopreventive agents is not likely to be affected by polymorphism in this enzyme.


Assuntos
Hidrocarboneto de Aril Hidroxilases/genética , Cumarínicos/farmacologia , Polimorfismo Genético , Alelos , Aminoácidos/química , Anticarcinógenos/farmacologia , Sequência de Bases , Ligação Competitiva , Cumarínicos/metabolismo , Citocromo P-450 CYP1B1 , DNA Complementar/metabolismo , Di-Hidroxi-Di-Hidrobenzopirenos/farmacologia , Relação Dose-Resposta a Droga , Furocumarinas/farmacologia , Variação Genética , Haplótipos , Humanos , Cinética , Microssomos/metabolismo , Modelos Químicos , Dados de Sequência Molecular , Oxigênio/metabolismo
14.
Carcinogenesis ; 24(7): 1247-55, 2003 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-12807732

RESUMO

Genetic differences that underlie inter-individual variation in the metabolism of common carcinogens are important potential sources of cancer susceptibility. Cytochrome P450 1B1 (CYP1B1), a central enzyme in the activation of the ubiquitous environmental carcinogen benzo[a]pyrene (B[a]P), has several genetic variants. This study investigated six rare mutations and four common polymorphisms for their effects on B[a]P metabolism. Five missense mutations associated with congenital glaucoma (Gly61Glu, Gly365Trp, Asp374Asn, Pro437Leu and Arg469Tryp) dramatically decreased the capacity of CYP1B1 to convert (-)benzo[a]pyrene-7R-trans-7,8-dihyrodiol (B[a]P-7,8-diol) to (+/-)benzo[a]pyrene-r-7,t-8-dihydrodiol-9,10-epoxides. These five mutations resulted in enzymes with 3-12% of normal activity when assayed in vitro using an Saccharomyces cerevisiae microsomal expression system. A 10 bp deletion mutation produced no detectable protein or activity. In contrast, proteins containing all possible combinations of four common single nucleotide polymorphisms (Arg48Gly, Ala199Ser, Val432Leu, Asn453Ser) had modest effects on B[a]P-7,8-diol metabolism. Michaelis-Menten analysis suggested that two alleles, Arg48, Ala119, Val432, Ser453 (RAVS) and Arg48, Ala119, Leu432, Ser453 (RALS), have KM values 2-fold lower than Arg48, Ala119, Val432, Ser453 (RAVN): 1.4+/-0.3 and 1.3+/-0.4 microM, respectively, compared with 2.8+/-0.8 microM (P<0.05). However, these differences could not be confirmed with direct measurements of rate at low substrate concentration. There were no significant differences for either of two other kinetic parameters, kcat or kcat/KM. Allele frequency analysis in three populations reveals the Ser453 variant is rare among those of Asian (<1%) and African ancestry (<4%), and more common in individuals of European ancestry (16%). Haplotypes containing the Ser453 variant were uncommon; only RALS was detectable in our small populations. The RALS allele occurred between 0.5% in Asians and 15% in Europeans. Our study demonstrates that rare, disease-associated mutations in CYP1B1 significantly decrease the enzyme's metabolism of B[a]P-7,8-diol; however, our results do not identify any major differences in this metabolism due to four common single amino acid polymorphisms.


Assuntos
Hidrocarboneto de Aril Hidroxilases/metabolismo , Di-Hidroxi-Di-Hidrobenzopirenos/metabolismo , Glaucoma/enzimologia , Glaucoma/genética , Microssomos/metabolismo , Mutação de Sentido Incorreto , Polimorfismo de Nucleotídeo Único , Hidrocarboneto de Aril Hidroxilases/genética , População Negra/genética , Citocromo P-450 CYP1B1 , Primers do DNA/química , Frequência do Gene , Genótipo , Haplótipos , Humanos , Microssomos/enzimologia , Mutagênese Sítio-Dirigida , NADH Desidrogenase/metabolismo , Oxirredução , Reação em Cadeia da Polimerase , Polimorfismo de Fragmento de Restrição , Saccharomyces cerevisiae/enzimologia , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA