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1.
J Genet Couns ; 31(3): 713-721, 2022 06.
Artículo en Inglés | MEDLINE | ID: mdl-34846769

RESUMEN

Due to the high prevalence of mental illness in the general population, genetic counselors are likely to encounter patients with mental illness in practice, regardless of specialty. However, previous studies have shown that recent graduates of genetic counseling programs do not feel comfortable discussing mental illness in clinical encounters. One possible explanation for this discomfort is stigma toward mental illness, a well-documented phenomenon both in society and in the healthcare field. Previous studies of this phenomenon in genetic counselors and trainees have relied on self-report measures and are vulnerable to social desirability bias. We sought to gain a holistic understanding of attitudes toward mental illness held by genetic counseling trainees by measuring implicit and explicit biases. This study assessed 141 responses from genetic counseling students and recent graduates from master's graduate programs across North America. They were asked to complete a survey, which included a demographic questionnaire, a scale that has been validated for use for a variety of healthcare professionals (Nordt et al. 2006, Schizophrenia Bulletin, 32, 709), measuring explicit attitudes toward those with depression and schizophrenia (i.e., social distance and stereotype endorsement), and an implicit association test. Mean scores on the social distance and stereotype endorsement scales were higher for schizophrenia than depression, indicating higher levels of explicit bias toward the former than the latter. Participants held slightly significant implicit bias toward individuals with either physical or mental illness. These data suggest that unconscious or implicit bias may not contribute to unpreparedness to address psychiatric disorders in clinical practice that has been previously reported by new graduates. Therefore, genetic counseling trainees may be receptive to clinically relevant education pertaining to mental illness. These results could inform the curriculum of genetic counseling programs and facilitate provision of services to this population.


Asunto(s)
Consejeros , Trastornos Mentales , Actitud del Personal de Salud , Consejeros/psicología , Asesoramiento Genético/psicología , Humanos , Trastornos Mentales/psicología , Estudiantes , Encuestas y Cuestionarios
2.
BMJ Open Diabetes Res Care ; 7(1): e000613, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-30899530

RESUMEN

Objective: While controversial, observational and randomized clinical trial data implicate the micronutrient selenium (Se) in the development of type 2 diabetes (T2D). The aim of this study was to test the hypothesis that Se supplementation adversely affects pancreatic ß-cell function and insulin sensitivity. Research design and methods: In a subset of 400 individuals participating in a randomized, placebo-controlled trial of Se at 200 µg/day for colorectal adenomatous polyps, fasting plasma glucose and insulin were measured before randomization and within 6 months of completing intervention. Change in the homeostasis model assessment-ß cell function (HOMA2-%ß) and insulin sensitivity (HOMA2-%S) were compared between arms. A subgroup of 175 (79 Se and 96 placebo) participants underwent a modified oral glucose tolerance test (mOGTT) at the end of intervention and change in glucose values was assessed. Results: No statistically significant differences were observed for changes in HOMA2-%ß or HOMA2-%S between those who received Se compared with placebo. After a mean of 2.9 years on study, mean HOMA2-%ß values were 3.1±24.0 and 3.1±29.8 for the Se and placebo groups, respectively (p=0.99). For HOMA2-%S, the values were -0.5±223.2 and 80.9±1530.9 for the Se and placebo groups, respectively (p=1.00). Stratification by sex or age did not reveal any statistically significant effects on insulin sensitivity by treatment group. For mOGTT, mean baseline fasting blood glucose concentrations were significantly higher among participants in the placebo group compared with the Se group (96.6±14.6 and 92.3±12.0, respectively; p=0.04), a trend which remained through the 20 min assessment. Conclusions: These findings do not support a significant adverse effect of daily Se supplementation with 200 µg/day of selenized yeast on ß-cell function or insulin sensitivity as an explanation for previously reported associations between Se and T2D. Further clarification of longer term effects of Se is needed. Clinical trial registry: NIH Clinical Trials.gov number NCT00078897.


Asunto(s)
Células Secretoras de Insulina/efectos de los fármacos , Selenio/efectos adversos , Adenoma/tratamiento farmacológico , Adulto , Anciano , Anciano de 80 o más Años , Neoplasias Colorrectales/tratamiento farmacológico , Suplementos Dietéticos/efectos adversos , Femenino , Humanos , Resistencia a la Insulina , Masculino , Persona de Mediana Edad , Pólipos/tratamiento farmacológico , Ensayos Clínicos Controlados Aleatorios como Asunto , Selenio/farmacología
4.
PLoS One ; 13(4): e0196398, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-29698447

RESUMEN

Drugs that inhibit cyclooxygenase (COX)-2 and the metabolism of arachidonic acid (ARA) to prostaglandin E2 are potent anti-inflammatory agents used widely in the treatment of joint and muscle pain. Despite their benefits, daily use of these drugs has been associated with hypertension, cardiovascular and gastrointestinal toxicities. It is now recognized that ARA is metabolized to a number of bioactive oxygenated lipids (oxylipins) by cyclooxygenase (COX), lipoxygenase (LOX), and cytochrome P450 (CYP450) enzymes. Currently, the contribution of individual variability in ARA metabolism in response to the COX-2 inhibitors and potential adverse effects remains poorly understood. Using patient samples from the randomized, placebo-controlled phase III selenium/celecoxib (Sel/Cel) trial for the prevention of colorectal adenomatous polyps, we analyzed plasma concentrations of 74 oxylipins in a subset of participants who received celecoxib (n = 90) or placebo (n = 95). We assessed the effect of celecoxib (with and without low dose aspirin) on circulating oxylipins and systolic blood pressure (SBP). Individual CYP450- and LOX- but not COX-derived metabolites were higher with celecoxib than placebo (P<0.05) and differences were greater among non-aspirin users. LOX derived 5- and 8-HETE were elevated with celecoxib and positively associated with systolic blood pressure (P = 0.011 and P = 0.019 respectively). 20-HETE, a prohypertensive androgen-sensitive CYP450 metabolite was higher with celecoxib absent aspirin and was positively associated with SBP in men (P = 0.040) but not women. Independent of celecoxib or aspirin, LOX derived metabolites from ARA were strongly associated with SBP including 5- and 8-HETE. These findings support oxylipins, particularly the ARA LOX-derived, in blood pressure control and indicate that pharmacologic inhibition of COX-2 has effects on LOX and CYP450 ARA metabolism that contribute to hypertension in some patients.


Asunto(s)
Pólipos Adenomatosos/prevención & control , Celecoxib/uso terapéutico , Inhibidores de la Ciclooxigenasa 2/uso terapéutico , Oxilipinas/sangre , Pólipos/prevención & control , Pólipos Adenomatosos/patología , Anciano , Antiinflamatorios no Esteroideos/uso terapéutico , Ácido Araquidónico/química , Ácido Araquidónico/metabolismo , Aspirina/uso terapéutico , Presión Sanguínea , Celecoxib/metabolismo , Colon/patología , Método Doble Ciego , Ácidos Grasos Omega-3/química , Ácidos Grasos Omega-3/metabolismo , Ácidos Grasos Omega-6/química , Ácidos Grasos Omega-6/metabolismo , Femenino , Humanos , Masculino , Persona de Mediana Edad , Efecto Placebo , Pólipos/patología , Selenio/uso terapéutico
5.
Cancer Prev Res (Phila) ; 10(1): 45-54, 2017 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-27777235

RESUMEN

Selenium and vitamin E micronutrients have been advocated for the prevention of colorectal cancer. Colorectal adenoma occurrence was used as a surrogate for colorectal cancer in an ancillary study to the Selenium and Vitamin E Cancer Prevention Trial (SELECT) for prostate cancer prevention. The primary objective was to measure the effect of selenium (as selenomethionine) on colorectal adenomas occurrence, with the effect of vitamin E (as α-tocopherol) supplementation on colorectal adenoma occurrence considered as a secondary objective. Participants who underwent lower endoscopy while in SELECT were identified from a subgroup of the 35,533 men randomized in the trial. Adenoma occurrence was ascertained from the endoscopy and pathology reports for these procedures. Relative Risk (RR) estimates and 95% confidence intervals (CI) of adenoma occurrence were generated comparing those randomized to selenium versus placebo and to vitamin E versus placebo based on the full factorial design. Evaluable endoscopy information was obtained for 6,546 participants, of whom 2,286 had 1+ adenomas. Apart from 21 flexible sigmoidoscopies, all the procedures yielding adenomas were colonoscopies. Adenomas occurred in 34.2% and 35.7%, respectively, of participants whose intervention included or did not include selenium. Compared with placebo, the RR for adenoma occurrence in participants randomized to selenium was 0.96 (95% CI, 0.90-1.02; P = 0.194). Vitamin E did not affect adenoma occurrence compared with placebo (RR = 1.03; 95% CI, 0.96-1.10; P = 0.38). Neither selenium nor vitamin E supplementation can be recommended for colorectal adenoma prevention. Cancer Prev Res; 10(1); 45-54. ©2016 AACR.


Asunto(s)
Adenoma/prevención & control , Antioxidantes/administración & dosificación , Neoplasias Colorrectales/prevención & control , Neoplasias de la Próstata/prevención & control , Selenometionina/administración & dosificación , alfa-Tocoferol/administración & dosificación , Adenoma/diagnóstico por imagen , Adenoma/epidemiología , Adenoma/patología , Anciano , Neoplasias Colorrectales/diagnóstico por imagen , Neoplasias Colorrectales/epidemiología , Neoplasias Colorrectales/patología , Suplementos Dietéticos , Humanos , Incidencia , Masculino , Persona de Mediana Edad , Neoplasias de la Próstata/epidemiología , Factores de Riesgo , Sigmoidoscopía
6.
J Natl Cancer Inst ; 108(12)2016 12.
Artículo en Inglés | MEDLINE | ID: mdl-27530657

RESUMEN

BACKGROUND: Selenium supplementation may help to prevent colorectal cancer; as precursors of colorectal cancer, colorectal adenomas are a surrogate for colorectal cancer. Selenium supplementation may increase risk of type 2 diabetes (T2D). METHODS: The Selenium and Celecoxib (Sel/Cel) Trial was a randomized, placebo controlled trial of selenium 200 µg daily as selenized yeast and celecoxib 400 mg once daily, alone or together, for colorectal adenoma prevention. Men and women between age 40 and 80 years were eligible following colonoscopic removal of colorectal adenomas. The primary outcome was adenoma development. Celecoxib was suspended because of cardiovascular toxicity in other trials, but accrual continued to selenium and placebo. A total of 1621 participants were randomly assigned to selenium or placebo, of whom 1374 (84.8%) were available for analysis. All statistical tests were two-sided. RESULTS: In the respective placebo and selenium arms of 689 and 685 participants, adenoma detection after medians of 33.6 (range = 0.0-85.1 months) and 33.0 months (range = 0.0-82.6 months) were 42.8% and 44.1% (relative risk [RR] = 1.03, 95% confidence interval [CI] = 0.91 to 1.16, P = .68). In participants with baseline advanced adenomas, adenoma recurrence was reduced by 18% with selenium (RR = 0.82, 95% CI = 0.71 to 0.96, P = .01). In participants receiving selenium, the hazard ratio for new-onset T2D was 1.25 (95% CI = 0.74 to 2.11, P = .41), with a statistically significantly increased risk of selenium-associated T2D among older participants (RR = 2.21; 95% CI = 1.04 to 4.67, P = .03). CONCLUSIONS: Overall, selenium did not prevent colorectal adenomas and showed only modest benefit in patients with baseline advanced adenomas. With limited benefit and similar increases in T2D to other trials, selenium is not recommended for preventing colorectal adenomas in selenium-replete individuals.


Asunto(s)
Adenoma/prevención & control , Neoplasias Colorrectales/prevención & control , Diabetes Mellitus Tipo 2/epidemiología , Neoplasias Primarias Secundarias/prevención & control , Selenio/administración & dosificación , Adenoma/diagnóstico por imagen , Adenoma/cirugía , Anciano , Neoplasias Colorrectales/diagnóstico por imagen , Neoplasias Colorrectales/cirugía , Inhibidores de la Ciclooxigenasa 2/administración & dosificación , Suplementos Dietéticos , Femenino , Estudios de Seguimiento , Humanos , Masculino , Cumplimiento de la Medicación , Persona de Mediana Edad , Neoplasias Primarias Secundarias/diagnóstico por imagen , Medición de Riesgo
8.
Cancer Prev Res (Phila) ; 8(1): 86-93, 2015 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-25388013

RESUMEN

Limonene is a lipophilic monoterpene found in high levels in citrus peel. Limonene demonstrates anticancer properties in preclinical models with effects on multiple cellular targets at varying potency. While of interest as a cancer chemopreventive, the biologic activity of limonene in humans is poorly understood. We conducted metabolite profiling in 39 paired (pre/postintervention) plasma samples from early-stage breast cancer patients receiving limonene treatment (2 g QD) before surgical resection of their tumor. Metabolite profiling was conducted using ultra-performance liquid chromatography coupled to a linear trap quadrupole system and gas chromatography-mass spectrometry. Metabolites were identified by comparison of ion features in samples to a standard reference library. Pathway-based interpretation was conducted using the human metabolome database and the MetaCyc database. Of the 397 named metabolites identified, 72 changed significantly with limonene intervention. Class-based changes included significant decreases in adrenal steroids (P < 0.01), and significant increases in bile acids (P ≤ 0.05) and multiple collagen breakdown products (P < 0.001). The pattern of changes also suggested alterations in glucose metabolism. There were 47 metabolites whose change with intervention was significantly correlated to a decrease in cyclin D1, a cell-cycle regulatory protein, in patient tumor tissues (P ≤ 0.05). Here, oral administration of limonene resulted in significant changes in several metabolic pathways. Furthermore, pathway-based changes were related to the change in tissue level cyclin D1 expression. Future controlled clinical trials with limonene are necessary to determine the potential role and mechanisms of limonene in the breast cancer prevention setting.


Asunto(s)
Neoplasias de la Mama/sangre , Ciclohexenos/uso terapéutico , Metaboloma , Terpenos/uso terapéutico , Aminoácidos/química , Anticarcinógenos/uso terapéutico , Antineoplásicos/química , Ácidos y Sales Biliares/química , Neoplasias de la Mama/tratamiento farmacológico , Carnitina/análogos & derivados , Carnitina/metabolismo , Ciclo Celular , Colágeno/química , Ciclina D1/metabolismo , Femenino , Cromatografía de Gases y Espectrometría de Masas , Glucosa/química , Humanos , Limoneno , Metabolómica , Plasma/metabolismo
9.
Prostate ; 73(3): 328-35, 2013 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-22887343

RESUMEN

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


Asunto(s)
Suplementos Dietéticos , Neoplasias de la Próstata/epidemiología , Selenio/administración & dosificación , Selenio/farmacología , Administración Oral , Anciano , Biopsia , Relación Dosis-Respuesta a Droga , Método Doble Ciego , Estudios de Seguimiento , Humanos , Incidencia , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Modelos de Riesgos Proporcionales , Antígeno Prostático Específico/sangre , Neoplasias de la Próstata/sangre , Neoplasias de la Próstata/patología , Factores de Riesgo , Selenio/efectos adversos
10.
Cancer Prev Res (Phila) ; 5(12): 1381-93, 2012 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-23060037

RESUMEN

COX inhibitors reduce colorectal adenoma recurrence by up to 45% and selenium supplementation may prevent colorectal cancer. Following colonoscopic adenoma resection, 1,600 men and women, ages 40 to 80 years, were randomized to celecoxib (400 mg daily), a selective COX-2 inhibitor, and/or selenium (200 µg daily as selenized yeast), or double placebo. The trial was initiated in November 2001. The primary trial endpoint is adenoma recurrence in each intervention group compared with placebo, as determined by surveillance colonoscopy conducted three to five years after baseline. Randomization was stratified by use of low-dose aspirin (81 mg) and clinic site. Following reports of cardiovascular toxicity associated with COX-2 inhibitors, the celecoxib arm was discontinued in December 2004 when 824 participants had been randomized. Accrual continued with randomization to selenium alone or placebo. Randomization of the originally planned cohort (n = 1,621) was completed in November 2008. A further 200 patients with one or more advanced adenomas (denoting increased risk for colorectal cancer) were accrued to enhance statistical power for determining intervention efficacy in this higher-risk subgroup. Accrual of the total cohort (n = 1,824) was completed in January 2011. Baseline cohort characteristics include: mean age 62.9 years; 65% male; body mass index (BMI) 29.1 ± 5.1; 47% taking low-dose aspirin while on trial; 20% with three or more adenomas; and 38% with advanced adenomas. Intervention effects on adenoma recurrence will be determined, and their modification by genetic background and baseline selenium level. The effect of selenium supplementation on risk for type II diabetes will also be reported.


Asunto(s)
Adenoma/prevención & control , Neoplasias Colorrectales/prevención & control , Pirazoles/administración & dosificación , Selenio/administración & dosificación , Sulfonamidas/administración & dosificación , Adulto , Anciano , Anciano de 80 o más Años , Índice de Masa Corporal , Celecoxib , Estudios de Cohortes , Femenino , Humanos , Masculino , Persona de Mediana Edad , Modelos Genéticos , Recurrencia , Proyectos de Investigación , Riesgo , Tamaño de la Muestra , Resultado del Tratamiento
11.
Cancer Prev Res (Phila) ; 3(8): 1035-43, 2010 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-20647337

RESUMEN

The Nutritional Prevention of Cancer trial showed a 52% lower incidence of prostate cancer in men supplemented with selenium. As a result, our study was designed to assess whether selenium supplementation attenuates the progression of prostate cancer. A phase 2 randomized, double-blind, placebo-controlled clinical trial was conducted in men with localized nonmetastatic prostate cancer who had elected to forgo active treatment and be followed by active surveillance. A total of 140 men were randomized to placebo (n = 46), 200 microg/d (n = 47), or 800 microg/d (n = 47) selenium p.o. (as selenized yeast) and followed every 3 months for up to 5 years. Prostate-specific antigen (PSA) velocity was used as a marker of prostate cancer progression and was estimated using mixed-effects regression. Adjusting for age, body mass index, baseline selenium, smoking, baseline PSA, race, PSA method, and Gleason score, PSA velocities for the 200 microg/d and 800 microg/d treatment groups were not statistically significantly different from placebo (P = 0.32 and P = 0.61, respectively). In the highest quartile of baseline selenium, men supplemented with 800 microg selenium showed statistically significantly higher PSA velocity as compared with placebo (P = 0.018). Selenium supplementation did not show a protective effect on PSA velocity in subjects with localized prostate cancer. On the contrary, supplementation with high-dose selenium was observed to be a risk factor for increased PSA velocity in men with high baseline plasma selenium concentrations.


Asunto(s)
Carcinoma/prevención & control , Antígeno Prostático Específico/metabolismo , Neoplasias de la Próstata/prevención & control , Selenio/administración & dosificación , Administración Oral , Adulto , Anciano , Anciano de 80 o más Años , Algoritmos , Carcinoma/sangre , Carcinoma/metabolismo , Carcinoma/patología , Suplementos Dietéticos/efectos adversos , Progresión de la Enfermedad , Método Doble Ciego , Humanos , Masculino , Persona de Mediana Edad , Placebos , Antígeno Prostático Específico/sangre , Neoplasias de la Próstata/sangre , Neoplasias de la Próstata/metabolismo , Neoplasias de la Próstata/patología , Selenio/efectos adversos
12.
Carcinogenesis ; 31(9): 1642-9, 2010 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-20624750

RESUMEN

Conjugated linoleic acid (CLA) is a class of commercially available fatty acids that have been associated with anticancer properties in rodent models of chemical carcinogenesis. We conducted a pilot study to examine the antitumor effect of dietary CLA in a polyoma virus-middle T antigen (PyMT) mouse model of invasive breast cancer. Virgin 4-week-old PyMT mice were administered a mixed-isomer CLA diet (1% wt/wt) or control AIN-93G diet for 4 weeks (N = 6 and 5, respectively) and tumor burden was assessed at 8 weeks of age. Thoracic mammary glands were prepared as whole mounts with other glands being formalin fixed and paraffin embedded for histology and immunohistochemistry (IHC). Total RNA was prepared for microarray and real-time reverse transcription-polymerase chain reaction analysis. Western blots were performed for protein expression analysis. Tumor incidence was significantly increased in CLA-treated animals compared with controls (P = 0.009) and occurred with extensive lobular-alveolar expansion and loss of mammary adipose tissue. More than 100 genes were downregulated > or = 2-fold in the CLA-treated group compared with controls, including adipose-specific markers, as wells as cytoskeletal and adhesion-related genes. This was supported by dramatic decreases in the epithelial adherens E-cadherin and beta-catenin as demonstrated by IHC. Taken together, these results suggest that dietary CLA affects the mammary stromal environment, leading to tumor progression and cellular expansion in the PyMT mouse model. Further studies of the potential for cancer promotion are needed, especially because mixed-isomer CLA formulations are sold commercially as a nutritional supplement.


Asunto(s)
Antígenos Transformadores de Poliomavirus/fisiología , Biomarcadores de Tumor/genética , Dieta , Perfilación de la Expresión Génica , Ácidos Linoleicos Conjugados/administración & dosificación , Neoplasias Mamarias Experimentales/genética , Neoplasias Mamarias Experimentales/patología , Animales , Biomarcadores de Tumor/metabolismo , Western Blotting , Proliferación Celular , Femenino , Técnicas para Inmunoenzimas , Neoplasias Mamarias Experimentales/metabolismo , Ratones , Ratones Transgénicos , Análisis de Secuencia por Matrices de Oligonucleótidos , Proyectos Piloto , ARN Mensajero/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa
13.
Adv Skin Wound Care ; 23(3): 116-9, 2010 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-20177164

RESUMEN

Hyperbaric oxygen therapy continues to be discussed as another adjunctive therapy in the continuum of wound care. There is a dearth of evidence from randomized clinical trials on HBO therapy. For evidence-based practice, more randomized, controlled studies need to be conducted with HBO therapy to determine its efficacy in treating other chronic wounds besides those of patients with diabetes.


Asunto(s)
Pie Diabético/terapia , Oxigenoterapia Hiperbárica/métodos , Cicatrización de Heridas , Heridas y Lesiones/terapia , Enfermedad Crónica , Pie Diabético/clasificación , Gangrena Gaseosa/terapia , Humanos , Úlcera de la Pierna/terapia , Osteomielitis/terapia , Ensayos Clínicos Controlados Aleatorios como Asunto , Resultado del Tratamiento , Heridas y Lesiones/clasificación
17.
Gastroenterology ; 131(6): 1706-16, 2006 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-17087956

RESUMEN

BACKGROUND & AIMS: Methylenetetrahydrofolate reductase (MTHFR) is involved in intracellular folate homeostasis and metabolism. We assessed 2 polymorphisms in the MTHFR gene (C677T and A1298C) in relation to colorectal adenoma recurrence and conducted analyses to investigate their joint effects with plasma and dietary markers of folate status. METHODS: We prospectively analyzed data from 1598 individuals genotyped for the C677T polymorphism and 1583 with data on A1298C. RESULTS: Among nonusers of multivitamin supplements, compared with wild-type carriage, higher odds of recurrence were observed for those with the 677 TT variant (odds ratio [OR], 1.66; 95% confidence interval [CI], 1.04-2.63) and a nonsignificant increase was observed among those with the 1298 CC variant (OR, 1.50; 95% CI, 0.93-2.40). Diplotype analyses among nonusers of multivitamins showed that individuals who carry the MTHFR 677TT_1298AA or 677CC_1298CC combination were significantly more likely to have a recurrence compared with those with the double wild-type (OR, 2.05 for TT_AA and 1.85 for CC_CC). Higher odds of recurrence were observed among participants with low folate intake or plasma folate and the 677 TT or 1298 CC variants compared with those with lower levels and the wild-type or heterozygous genotypes. Stronger associations were shown for the combination of high homocysteine and the 677 TT variant (OR, 2.29; 95% CI, 1.00-5.26) but not the 1298 CC variant (OR, 1.09; 95% CI, 0.39-3.01). CONCLUSIONS: We propose that the effect of the MTHFR genotypes on increasing risk of adenoma recurrence in the presence of a low folate status is through their increase in homocysteine concentrations, which in turn could result in DNA hypomethylation via pathways involving S-adenosylhomocysteine.


Asunto(s)
Adenoma/sangre , Adenoma/genética , Neoplasias Colorrectales/sangre , Neoplasias Colorrectales/genética , Ácido Fólico/administración & dosificación , Ácido Fólico/sangre , Homocisteína/sangre , Metilenotetrahidrofolato Reductasa (NADPH2)/genética , Polimorfismo Genético , Anciano , Biomarcadores de Tumor/sangre , Carbono/metabolismo , Metilación de ADN , Suplementos Dietéticos , Femenino , Genotipo , Homeostasis , Humanos , Masculino , Persona de Mediana Edad , Recurrencia Local de Neoplasia/sangre , Recurrencia Local de Neoplasia/genética , Estudios Prospectivos , Factores de Riesgo , Vitaminas/administración & dosificación
19.
Int J Cancer ; 119(6): 1440-6, 2006 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-16615116

RESUMEN

In 1996, the US Food and Drug Administration mandated the fortification of grain products with folic acid, a nutrient that has been associated with lower risk of colorectal neoplasia. We assessed the relation of plasma folate and homocysteine and colorectal adenoma recurrence separately in 2 studies: the first involved an intervention of a cereal supplement that contained folic acid, wheat bran fiber (WBF), and the second was conducted primarily during postfortification of the food supply using ursodeoxycholic acid (UDCA). Analyses were stratified for multivitamin use. Results show that plasma folate and homocysteine concentrations were associated with adenoma recurrence among nonusers of multivitamins only. Among nonmultivitamin users, the odds ratio [OR] (95% confidence interval [CI]) for those in the highest versus the lowest folate quartile was 0.65 (0.40-1.06) for the WBF study and 0.56 (0.31-1.02) for the UDCA; likewise, individuals in the highest versus the lowest quartile of homocysteine had higher odds of adenoma recurrence, in both the WBF (OR = 2.25; 95% CI = 1.38-3.66) and UDCA (OR = 1.93; 95% CI = 1.07-3.49) populations. Analyses comparing multivitamin users to different plasma folate concentrations among nonusers show that odds of recurrence for supplement users was lower only when compared to nonusers who had lower concentrations. Our results show that higher plasma folate or lower homocysteine levels are associated with lower odds of recurrence among nonusers of multivitamins in both studies. Our finding, suggesting that multivitamins or supplemental folate only benefit individuals with lower plasma folate concentrations, should be taken into consideration when designing and interpreting results of intervention studies.


Asunto(s)
Adenoma/sangre , Neoplasias Colorrectales/sangre , Ácido Fólico/sangre , Alimentos Fortificados , Homocisteína/sangre , Recurrencia Local de Neoplasia/sangre , Anciano , Dieta , Fibras de la Dieta , Suplementos Dietéticos , Método Doble Ciego , Femenino , Ácido Fólico/administración & dosificación , Humanos , Masculino , Factores de Riesgo , Ácido Ursodesoxicólico/administración & dosificación , Complejo Vitamínico B/administración & dosificación
20.
Mutat Res ; 523-524: 193-200, 2003.
Artículo en Inglés | MEDLINE | ID: mdl-12628517

RESUMEN

The chemopreventive effect of tea against 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)-DNA adduct formation and its mechanism were studied. Rats were exposed to freshly prepared aqueous extracts of green tea (3% (w/v)) as the sole source of drinking water for 10 days prior to administration with a single dose of PhIP (10 mg/kg body weight) by oral gavage. PhIP-DNA adducts in the liver, colon, heart, and lung were measured using the 32P-postlabelling technique. Rats pre-treated with tea and given PhIP 20 h before sacrifice had significantly reduced levels of PhIP-DNA adducts as compared with controls given PhIP alone. The possible mechanism of protective effect of tea on PhIP-DNA adduct formation was then examined in vitro. It was found that an aqueous extract of green and black tea, mixtures of green and black tea polyphenols, as well as purified polyphenols could strongly inhibit the DNA binding of N-acetoxy-PhIP, a putative ultimate carcinogen of PhIP formed in vivo via metabolic activation. Among these, epigallocatechin gallate was exceptionally potent. HPLC analyses of these incubation mixtures containing N-acetoxy-PhIP and the tea polyphenols each revealed the production of the parent amine, PhIP, indicating the involvement of a redox mechanism. In view of the presence of relatively high levels of tea polyphenols in rat and human plasma after ingestion of tea, this study suggests that direct reduction of the ultimate carcinogen N-acetoxy-PhIP by tea polyphenols is likely to be involved in the mechanism of chemoprotection of tea against this carcinogen.


Asunto(s)
Anticarcinógenos/farmacología , Carcinógenos/química , Aductos de ADN , Flavonoides , Imidazoles/química , Imidazoles/farmacocinética , Fenoles/farmacología , Polímeros/farmacología , Piridinas/química , , Animales , Masculino , Oxidación-Reducción , Polifenoles , Ratas , Ratas Sprague-Dawley , Distribución Tisular
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