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1.
Mar Pollut Bull ; 167: 112312, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33836333

RESUMO

Microplastics are a global concern, and yet, Philippine studies about it are still wanting. This study investigated microplastic ingestion among detritus-feeding mullet versus the herbivorous rabbitfish, and between freshwater and marine fishes. The first part aimed to compare microplastics in fishes' guts differing in feeding guilds, individual sizes, and body weights. The second part compared MPs in fishes' guts and their surrounding waters. Part one revealed that herbivores (58.57%) ingested more MPs than their detritivore-counterparts (30.0%). Pearson correlation, averaging 0.06, suggests a weak correlation between fish weight and MPs amount for both species. Part two showed marine fishes (66.0%) ingested more MPs than its freshwater counterparts (45.0%). A very weak correlation was observed between fish weight and amount of MPs ingested. Fish along the estuary ingested more MPs than those in other stations. No significant differences (p = 0.23) between the MPs in the water samples from each sampling stations was found.


Assuntos
Microplásticos , Poluentes Químicos da Água , Animais , Monitoramento Ambiental , Peixes , Filipinas , Plásticos , Poluentes Químicos da Água/análise
2.
PLoS One ; 14(12): e0225591, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31841512

RESUMO

BACKGROUND: Positive associations have been found between Hypertensive Disorders of Pregnancy gestational hypertension, preeclampsia and cardiovascular diseases within non-African populations, no data exist from sub-Saharan Africa. We aimed to assess this association in Cameroonian mothers. METHODS: We used a case-control study. Cases were women diagnosed with any arteriosclerotic cardiovascular disease between 2012 and 2017 at two major hospitals of Yaoundé. Controls were mothers of children who sought pediatric care at the Gyneco-obstetric hospital of Yaoundé, with no diagnosis of cardiovascular disease. We abstracted data from patient files to assess cardiovascular disease and used phone-based questionnaires to assess a prior history of Hypertensive Disorders of Pregnancy. We used logistic regression and propensity scores for data analysis. RESULTS: Out of 1228 individuals selected, 173 cases and 339 controls participated in the study. We found no increased risk of cardiovascular diseases for women with a history of Hypertensive Disorders of Pregnancy (OR = 0.83, 95% CI, 0.51 to 1.34). Women with gestational hypertension had 2.33 (95% CI, 0.99 to 5.50) times the risk of women with no history of Hypertensive Disorders of Pregnancy, an inverse association was observed between preeclampsia and cardiovascular diseases (OR = 0.28, 95% CI, 0.10 to 0.72). CONCLUSIONS: Cameroonian women with a history of gestational hypertension may have a higher risk of cardiovascular diseases. However, population-based studies with more accurate data on the exposure are needed.


Assuntos
Arteriosclerose/epidemiologia , Hipertensão Induzida pela Gravidez/epidemiologia , Pré-Eclâmpsia/epidemiologia , Adulto , Arteriosclerose/complicações , Camarões/epidemiologia , Estudos de Casos e Controles , Feminino , Humanos , Hipertensão Induzida pela Gravidez/etiologia , Anamnese/estatística & dados numéricos , Pessoa de Meia-Idade , Pré-Eclâmpsia/etiologia , Gravidez , Fatores de Risco , Inquéritos e Questionários/estatística & dados numéricos , Adulto Jovem
3.
Am J Physiol Lung Cell Mol Physiol ; 310(11): L1218-32, 2016 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-27130530

RESUMO

Chronic lung disease of prematurity (CLD) is a frequent sequela of premature birth and oxygen toxicity is a major associated risk factor. Impaired alveolarization, scarring, and inflammation are hallmarks of CLD. Mast cell hyperplasia is a feature of CLD but the role of mast cells in its pathogenesis is unknown. We hypothesized that mast cell hyperplasia is a consequence of neonatal hyperoxia and contributes to CLD. Additionally, mast cell products may have diagnostic and prognostic value in preterm infants predisposed to CLD. To model CLD, neonatal wild-type and mast cell-deficient mice were placed in an O2 chamber delivering hyperoxic gas mixture [inspired O2 fraction (FiO2 ) of 0.8] (HO) for 2 wk and then returned to room air (RA) for an additional 3 wk. Age-matched controls were kept in RA (FiO2 of 0.21). Lungs from HO mice had increased numbers of mast cells, alveolar simplification and enlargement, and increased lung compliance. Mast cell deficiency proved protective by preserving air space integrity and lung compliance. The mast cell mediators ß-hexosaminidase (ß-hex), histamine, and elastase increased in the bronchoalveolar lavage fluid of HO wild-type mice. Tracheal aspirate fluids (TAs) from oxygenated and mechanically ventilated preterm infants were analyzed for mast cell products. In TAs from infants with confirmed cases of CLD, ß-hex was elevated over time and correlated with FiO2 Mast cell exosomes were also present in the TAs. Collectively, these data show that mast cells play a significant role in hyperoxia-induced lung injury and their products could serve as potential biomarkers in evolving CLD.


Assuntos
Displasia Broncopulmonar/patologia , Exossomos/metabolismo , Hiperóxia/patologia , Mastócitos/metabolismo , Animais , Animais Recém-Nascidos , Displasia Broncopulmonar/imunologia , Displasia Broncopulmonar/metabolismo , Células Cultivadas , Humanos , Hiperóxia/imunologia , Hiperóxia/metabolismo , Recém-Nascido , Pulmão/imunologia , Pulmão/patologia , Camundongos , Proteoma/metabolismo , Traqueia/metabolismo
4.
Elife ; 5: e10066, 2016 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-26780670

RESUMO

Innate lymphoid cells (ILCs) contribute to host defence and tissue repair but can induce immunopathology. Recent work has revealed tissue-specific roles for ILCs; however, the question of how a small population has large effects on immune homeostasis remains unclear. We identify two mechanisms that ILC3s utilise to exert their effects within intestinal tissue. ILC-driven colitis depends on production of granulocyte macrophage-colony stimulating factor (GM-CSF), which recruits and maintains intestinal inflammatory monocytes. ILCs present in the intestine also enter and exit cryptopatches in a highly dynamic process. During colitis, ILC3s mobilize from cryptopatches, a process that can be inhibited by blocking GM-CSF, and mobilization precedes inflammatory foci elsewhere in the tissue. Together these data identify the IL-23R/GM-CSF axis within ILC3 as a key control point in the accumulation of innate effector cells in the intestine and in the spatio-temporal dynamics of ILCs in the intestinal inflammatory response.


Assuntos
Colite/patologia , Fator Estimulador de Colônias de Granulócitos e Macrófagos/metabolismo , Imunidade Inata , Intestinos/imunologia , Linfócitos/imunologia , Humanos , Subunidade p19 da Interleucina-23/metabolismo
5.
Clin Ther ; 38(2): 288-296.e2, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26730455

RESUMO

PURPOSE: Statin therapy has been reported to reduce the incidence of vascular events in patients with atherosclerosis, but adherence to statins may be suboptimal. The aims of this study were to quantify the rate of statin use among individuals with a history of coronary revascularization in a large, integrated health care system and to determine which demographic characteristics and clinical factors are associated with statin use. METHODS: This was a retrospective cohort study using database programming and chart review. The study included adult members of Kaiser Permanente Northern California with a history of coronary revascularization. The study outcome was off-statin status, defined as a ≥1-year gap between filled prescriptions. The predictor variables included age, race, body mass index, dyslipidemia, liver disease, kidney disease, and history of statin allergy. Multivariable logistic regression was used to quantify the associations between the predictor variables and statin status. A chart review of a randomly selected subset was performed to identify reasons why individuals were not taking statins. FINDINGS: The study population included 17,869 Kaiser Permanente Northern California members, of which 18.3% had off-statin status. The following variables were associated with off-statin status: statin allergy (odds ratio [OR] = 2.18; 95% CI, 1.89-2.52), end-stage renal disease (OR = 1.55; 95% CI, 1.26-1.91), liver disease (OR = 1.44; 95% CI, 1.08-1.93), African-American race (OR = 1.55 vs white; 95% CI, 1.32-1.81), and Latino race (OR = 1.18; 95% CI, 1.05-1.33). The chart review found that off-statin status typically reflects patient (79%) rather than provider (21%) preference. IMPLICATIONS: A significant minority of patients with a history of coronary revascularization are not taking statins. Off-statin status is associated with kidney disease, liver disease, African-American race, and Latino race. At an individual level, off-statin status was usually driven by patient preference, due to minor or undefined reasons. These findings may be useful in guiding strategies to increase statin use in individuals with atherosclerosis.


Assuntos
Aterosclerose/tratamento farmacológico , Dislipidemias/tratamento farmacológico , Inibidores de Hidroximetilglutaril-CoA Redutases/uso terapêutico , Idoso , California/epidemiologia , Estudos de Coortes , Feminino , Humanos , Incidência , Falência Renal Crônica/epidemiologia , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos
6.
Blood ; 124(23): 3389-97, 2014 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-25339360

RESUMO

The effect of recombinant factor VIII (rFVIII) brand on inhibitor development was investigated in all 407 severe hemophilia A previously untreated patients born in the United Kingdom (UK) between 1 January 2000 and 31 December 2011. Eighty-eight (22%) had been in the RODIN study. Information was extracted from the National Haemophilia Database. Because exposure days (EDs) were not known for some patients, time from first treatment was used as a surrogate for rFVIII exposure. An inhibitor developed in 118 (29%) patients, 60 high and 58 low titer, after a median (interquartile range) of 7.8 (3.3-13.5) months from first exposure and 16 (9-30) EDs. Of 128 patients treated with Kogenate Bayer/Helixate NexGen, 45 (35.2%, 95% confidence interval [CI] 27.4-43.8) developed an inhibitor compared with 42/172 (24.4%, 95% CI 18.6% to 31.4%) with Advate (P = .04). The adjusted hazard ratio (HR) (95% CI) for Kogenate Bayer/Helixate NexGen compared with Advate was 2.14 (1.12-4.10) (P = .02) for high titer and 1.75 (1.11-2.76) (P = .02) for all inhibitors. When excluding UK-RODIN patients, the adjusted HR (95% CI) for high-titer inhibitors was 2.00 (0.93-4.34) (P = .08). ReFacto AF was associated with a higher incidence of all, but not high-titer, inhibitors than Advate. These results will help inform debate around the relative immunogenicity and use of rFVIII brands.


Assuntos
Fator VIII/imunologia , Fator VIII/uso terapêutico , Hemofilia A/tratamento farmacológico , Hemofilia A/epidemiologia , Isoanticorpos/sangue , Formação de Anticorpos , Criança , Pré-Escolar , Estudos de Coortes , Fator VIII/antagonistas & inibidores , Hemofilia A/imunologia , Humanos , Incidência , Lactente , Recém-Nascido , Índice de Gravidade de Doença , Reino Unido/epidemiologia
7.
PLoS One ; 7(2): e32193, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22363815

RESUMO

NF-κB signalling plays an essential role in T cell activation and generation of regulatory and memory populations in vivo. In the present study, we aimed to investigate the role of NF-κB signalling in post-activation T cells using tissue specific ablation of inhibitor of kappa-B kinase 2 expression, an important component of the inhibitor of kappa-B kinase complex in canonical NF-κB signalling. The OX40 antigen is expressed on activated T cells. Therefore, we used previously described mouse strain expressing Cre recombinase from the endogenous OX40 locus. Ablation of IKK2 expression using OX40(Cre) mice resulted in the development of an inflammatory response in the skin epidermis causing wide spread skin lesions. The inflammatory response was characterised by extensive leukocytic infiltrate in skin tissue, hyperplasia of draining lymph nodes and widespread activation in the T cell compartment. Surprisingly, disease development did not depend on T cells but was rather associated with an unanticipated expression of Cre in skin epidermis, and activation of the T cell compartment did not require Ikbk2 deletion in T cells. Employment of Cre reporter strains revealed extensive Cre activity in skin epidermis. Therefore, development of skin lesions was rather more likely explained by deletion of Ikbk2 in skin keratinocytes in OX40(Cre) mice.


Assuntos
Epiderme/enzimologia , Deleção de Genes , Loci Gênicos/genética , Quinase I-kappa B/metabolismo , Integrases/metabolismo , Receptores OX40/metabolismo , Animais , Apoptose , Epiderme/imunologia , Epiderme/patologia , Epitélio/patologia , Genes Reporter/genética , Proteínas de Homeodomínio/metabolismo , Hipertrofia , Inflamação/patologia , Ativação Linfocitária/imunologia , Tecido Linfoide/patologia , Camundongos , Especificidade de Órgãos , Linfócitos T/imunologia , Fator de Necrose Tumoral alfa/biossíntese
8.
Immunol Cell Biol ; 88(2): 213-9, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19949423

RESUMO

Interleukin (IL)-7 and IL-15 have non-redundant roles in promoting development of memory CD8(+) T cells. STAT5 is activated by receptors of both cytokines and has also been implicated as a requirement for generation of memory. To determine whether STAT5 activity was required for IL-7 and IL-15-mediated generation of memory, we expressed either wild type (WT) or constitutively active (CA) forms of STAT5a in normal effector cells and then observed their ability to form memory in cytokine replete or deficient hosts. Receptor-independent CA-STAT5a significantly enhanced memory formation in the absence of either cytokine but did not mediate complete rescue. Interestingly, WT-STAT5a expression enhanced memory formation in a strictly IL-7-dependent manner, suggesting that IL-7 is a more potent activator of STAT5 than IL-15 in vivo. These data suggest that the non-redundant requirement for IL-7 and IL-15 is mediated through differential activation of both STAT5-dependent and STAT5-independent pathways.


Assuntos
Linfócitos T CD8-Positivos/imunologia , Memória Imunológica/imunologia , Interleucina-15/imunologia , Interleucina-7/imunologia , Fator de Transcrição STAT5/imunologia , Animais , Camundongos , Camundongos Transgênicos , Proteínas Mutantes/metabolismo , Fosforilação , Receptores de Antígenos de Linfócitos T/imunologia , Receptores de Interleucina-7/metabolismo , Retroviridae/genética , Transdução Genética
9.
Hemoglobin ; 30(4): 463-70, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-16987801

RESUMO

Blood counts, hemoglobin (Hb) high performance liquid chromatography (HPLC), and DNA analyses were performed on 260 children, aged 5 months to 16 years, at Siem Reap to assess the prevalence of thalassemia and other hemoglobinopathies in regional Cambodia. Hemoglobinopathies were present in 134 children (51.5%) with 20 abnormal genotypes identified. alpha-Thalassemia (thal) (35.4%) was the most prevalent disorder and the -alpha3.7 gene deletion was the most common alpha-globin gene abnormality. The - -SEA deletion and nondeletional forms of alpha-thal, Hb Constant Spring [Hb CS, alpha142, Term-->Gln, TAA-->CAA (alpha2)], Hb Paksé [alpha142, Term-->Tyr, TAA-->TAT (alpha2)] and triplicated alpha genes, were also present but at low frequencies. Hb E [beta26(B8)Glu-->Lys, GAG-->AAG] (28.8%) was the most common beta-globin gene abnormality, whilst beta-thal was only detected in two children (0.8% of cases). Although hemoglobinopathies were common, the majority of abnormalities detected (heterozygous -alpha3.7 and Hb E) were not clinically significant. On the basis of these findings, and with the majority of abnormalities being mild, it seems improbable that thalassemia represents a major health burden in this region of Cambodia.


Assuntos
Globinas/genética , Talassemia alfa/genética , Talassemia beta/genética , Adolescente , Contagem de Células Sanguíneas , Camboja/epidemiologia , Criança , Pré-Escolar , Cromatografia Líquida de Alta Pressão , Estudos Transversais , Feminino , Hemoglobina E/genética , Hemoglobinas Anormais/genética , Humanos , Lactente , Masculino , Reação em Cadeia da Polimerase , Prevalência , Análise de Sequência de DNA , Talassemia alfa/epidemiologia , Talassemia beta/epidemiologia
11.
Circulation ; 100(19 Suppl): II357-60, 1999 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-10567329

RESUMO

BACKGROUND: Hypothermic myocardial arrest is necessary to complete most cardiac surgery, which limits the success of such operations. Similarly, cold, inhospitable environments limit the survival of warm-blooded animals. Animals have successfully adapted to this challenge through hibernation. Hibernation is an energy-conserving state, now known to be governed by cyclical variation in endogenous opiate compounds. It may also be induced in nonhibernators via hibernating animal serum factors or delta-opiate peptides. Furthermore, hibernation-induction triggers extend organ preservation in many models. This study examined whether opiate drugs with an affinity for the delta-opiate receptor confer similar protection. METHODS AND RESULTS: Isolated hearts harvested from New Zealand White rabbits were treated with either cardioplegia alone or delta-opiate drugs (fentanyl, morphine, buprenorphine, pentazocine) followed by 2 hours of 34 degrees C ischemia. Hearts were then reperfused, and functional and metabolic indices of treated groups were compared with untreated controls. Isovolumic developed pressure, coronary flow, and oxygen consumption were compared as a percent of preischemia versus 45 minutes after reflow. Developed pressure and oxygen consumption were better preserved in the morphine, buprenorphine, and pentazocine groups when compared with cardioplegia alone. CONCLUSIONS: Drugs with delta-opiate activity confer myocardial protection, which is additive to cardioplegia. Use of delta-opiate drugs in this context may have important clinical implications.


Assuntos
Analgésicos Opioides/farmacologia , Ponte Cardiopulmonar , Coração/fisiopatologia , Isquemia Miocárdica/prevenção & controle , Receptores Opioides delta/agonistas , Receptores Opioides delta/fisiologia , Animais , Buprenorfina/farmacologia , Fentanila/farmacologia , Morfina/farmacologia , Isquemia Miocárdica/fisiopatologia , Pentazocina/farmacologia , Coelhos
14.
Lancet ; 347(9014): 1507-10, 1996 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-8684101

RESUMO

BACKGROUND: Upper-respiratory-tract infection is one of the main causes of overuse of antibiotics. We have found previously that bacteria such as Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumoniae can be isolated from the nasopharyngeal secretions of a substantial proportion of adults with upper-respiratory-tract infections. We have assessed the efficacy of co-amoxiclav in patients with common colds but no clinical signs of sinusitis or other indications for antibiotics. METHODS: Between January, 1992 and March, 1994, 314 patients who presented to our outpatient clinic with common colds were enrolled in the double-blind, placebo-controlled study. They were randomly assigned 5 days' treatment with co-amoxiclav (375 mg three times daily) or identical placebo. Clinical examinations were done at enrolment and on day 5-7 to assess outcome (cured, persistent symptoms, worse symptoms). Seven patients were excluded after randomisation, seven did not have nasopharyngeal aspiration, and 12 did not return for followup assessment. FINDINGS: Of 300 patients with nasopharyngeal aspirates, 72 had negative bacterial cultures, 167 had cultures positive only for bacteria unrelated to respiratory infections, and 61 had cultures positive for H influenzae, M catarrhalis, or S pneumoniae. At 5-day follow-up of these culture-positive patients, the distribution of outcome was significantly better among co-amoxiclav-treated (n=30) than placebo-treated (n=28) patients (cured 27 vs 4%; persistent symptoms 70 vs 60%; worse symptoms 3 vs 36%; p=0.001). Patients on co-amoxiclav also scored their symptoms significantly lower than patients on placebo (p=0.008). Among culture-negative patients (n=230), the outcome distribution did not differ between the treatment groups (p=0.392). INTERPRETATION: The majority of patients with upper-respiratory-tract infection do not benefit from antibiotics and side-effects are frequent. However, for the subgroup whose nasopharyngeal secretions contain H influenzae, M catarrhalis, or S pneumoniae, antibiotics are clinically beneficial.


Assuntos
Infecções Bacterianas/tratamento farmacológico , Resfriado Comum/tratamento farmacológico , Resfriado Comum/microbiologia , Quimioterapia Combinada/uso terapêutico , Nasofaringe/microbiologia , Adulto , Amoxicilina/uso terapêutico , Combinação Amoxicilina e Clavulanato de Potássio , Ácidos Clavulânicos/uso terapêutico , Método Duplo-Cego , Feminino , Infecções por Haemophilus/tratamento farmacológico , Haemophilus influenzae/isolamento & purificação , Humanos , Masculino , Moraxella catarrhalis/isolamento & purificação , Infecções por Neisseriaceae/tratamento farmacológico , Infecções Pneumocócicas/tratamento farmacológico , Resultado do Tratamento
15.
Clin Pharmacol Ther ; 57(1): 16-24, 1995 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-7828377

RESUMO

Midazolam, a commonly used sedative and amnestic medication, has recently been shown to be largely metabolized in the liver by a cytochrome P450, termed CYP3A4. There is at least a tenfold intersubject variability in the liver content and catalytic activity of CYP3A4, which may in part account for the known interpatient differences in the kinetics of midazolam. To test this hypothesis, we determined the intravenous midazolam kinetics of 20 medically stable, hospitalized patients, whose hepatic CYP3A4 activities were determined with use of the [14C-N-methyl]erythromycin breath test. During the kinetic study, we also performed psychometric testing designed to quantitate the level of sedation and amnesia. We found a significant positive correlation between the erythromycin breath test results and weight adjusted clearance (in milliliters per minute per kilogram) of both total midazolam (r = 0.52; p = 0.03) and unbound midazolam (r = 0.61; p < 0.01). The relatively low dose of midazolam used (0.0145 mg/kg) produced significant but transient sedation and memory impairment in some of the patients. We conclude that interpatient differences in liver CYP3A4 activity in part account for the variations in midazolam kinetics. Our observations account for reported drug interactions involving midazolam and suggest that patients with low CYP3A4 activity may be most susceptible to prolonged amnestic effects occasionally produced by this short-acting benzodiazepine.


Assuntos
Testes Respiratórios , Eritromicina/análise , Midazolam/farmacocinética , Adulto , Sistema Enzimático do Citocromo P-450/metabolismo , Interações Medicamentosas , Feminino , Meia-Vida , Humanos , Injeções Intravenosas , Masculino , Memória/efeitos dos fármacos , Taxa de Depuração Metabólica , Valor Preditivo dos Testes , Psicometria , Fatores Sexuais
16.
Hosp Community Psychiatry ; 45(5): 475-80, 1994 May.
Artigo em Inglês | MEDLINE | ID: mdl-8045544

RESUMO

OBJECTIVE: This study investigated the contributions that persons with serious mental illness make to their families according to both clients and family respondents. METHODS: The sample consisted of 725 clients with serious mental illness and 725 family respondents living in rural counties or counties with small urban areas in Wisconsin. Clients were in contact with family respondents at least three times a year; 23.7 percent of them lived with the respondent. Clients returned a questionnaire, and family respondents completed a telephone interview; both rated the amount of help the client gave in eight areas such as household chores, shopping, and companionship. RESULTS: Overall, the clients, especially those who lived with their families, provided substantial help. For the total sample, clients were most likely to contribute by providing companionship; family respondents reported that 59 percent of clients gave such help. For clients who lived with respondents, between 50 and 80 percent helped by doing household chores, shopping, listening to problems, providing companionship, and providing news about family and friends, according to family respondents. CONCLUSIONS: Many persons with severe mental illness play positive roles in their families. Recognition of clients' contributions by providers, researchers, and clients and families themselves could help reduce stigma and expand community opportunities for persons with severe mental illness.


Assuntos
Atividades Cotidianas/psicologia , Cuidadores/psicologia , Família/psicologia , Transtornos Mentais/psicologia , Papel do Doente , Adulto , Idoso , Efeitos Psicossociais da Doença , Feminino , Humanos , Masculino , Transtornos Mentais/reabilitação , Pessoa de Meia-Idade , Transtornos Psicóticos/psicologia , Transtornos Psicóticos/reabilitação , Esquizofrenia/reabilitação , Psicologia do Esquizofrênico , Apoio Social
17.
Gastroenterology ; 106(2): 433-9, 1994 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-8299909

RESUMO

BACKGROUND/AIMS: Hepatic CYP3A enzymes have been implicated in the bioactivation of aflatoxin B1 (AFB1) to DNA binding metabolites. CYP3A enzymes are also abundant in the small bowel, and we therefore examined the ability of this tissue to form intracellular AFB1 adducts. METHODS: Immunohistochemistry using a antibody to the stable AFB1-DNA adduct was performed on small bowel sections obtained from rats orally gavaged with AFB1 and on human small bowel biopsy specimens maintained in explant culture. 3H-AFB1 was instilled into a loop of small bowel of untreated rats and rats pretreated with the CYP3A inducer dexamethasone during vivisection. DNA was isolated from the loop 2 hours later and assayed for specific activity. RESULTS: In both rats and humans, AFB1-adducts were detected exclusively in mature enterocytes in a pattern similar to the distribution of CYP3A enzymes. Induction of enterocyte CYP3A in rats resulted in an increase in enterocyte immunoreactive AFB1 adducts and in a 1.8-fold increase in 3H-AFB1-nucleic acid adducts (P = 0.01). CONCLUSIONS: Intracellular AFB1 adducts are formed in the small intestine, and this reflects, at least in part, the catalytic activity of CYP3A enzymes. Because these AFB1 adducts should ultimately pass in stool, enterocyte CYP3A may represent a regulatable barrier to dietary aflatoxins.


Assuntos
Aflatoxina B1/metabolismo , Adutos de DNA , DNA/metabolismo , Intestino Delgado/metabolismo , Animais , Sistema Enzimático do Citocromo P-450/genética , Sistema Enzimático do Citocromo P-450/fisiologia , Feminino , Humanos , Imuno-Histoquímica , Intestino Delgado/citologia , Isoenzimas/fisiologia , Ratos , Ratos Sprague-Dawley
18.
Biochem Pharmacol ; 46(5): 905-18, 1993 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-8373442

RESUMO

Enzymes within the CYP3A subfamily are major Phase I drug-metabolizing enzymes present in hepatocytes and small bowel enterocytes. These enzymes are highly inducible in the liver by many structurally diverse compounds, including a number of commonly used medications. Studies indicate that CYP3A enzymes present in small bowel enterocytes are also inducible. However, the regulation of CYP3A enzymes in this tissue has not been well characterized, in part because in vivo studies are difficult, especially in humans. Our goals was to develop an in vitro model to study the regulation of CYP3A in enterocytes. To this end, we defined culture conditions under which adult rat jejunal explants maintained viable appearing villi for 21 hr. When dexamethasone, the prototypical inducer of CYP3A1 in rat hepatocytes, was added to the culture medium, there was a time-dependent induction of CYP3A1 mRNA and CYP3A protein in explant enterocytes which was essentially indistinguishable from the time course of induction of CYP3A1 mRNA and protein in enterocytes in vivo. This effect of dexamethasone appeared to be specific since dexamethasone had no consistent effect on the explant concentration of another enterocyte specific mRNA, intestinal fatty acid binding protein. Using this explant culture model, we found that CYP3A1 mRNA was also inducible by clotrimazole but we were unable to detect induction by rifampicin or troleandomycin. Our observations suggest that jejunal explants may provide an appropriate model for the study of the regulation of CYP3A and other drug-metabolizing enzymes.


Assuntos
Hidrocarboneto de Aril Hidroxilases , Sistema Enzimático do Citocromo P-450/genética , Isoenzimas/genética , Jejuno/enzimologia , Animais , Clotrimazol/farmacologia , Citocromo P-450 CYP3A , Sistema Enzimático do Citocromo P-450/biossíntese , Dexametasona/farmacologia , Indução Enzimática/efeitos dos fármacos , Feminino , Regulação da Expressão Gênica , Jejuno/citologia , Jejuno/ultraestrutura , Modelos Biológicos , RNA Mensageiro/análise , Ratos , Ratos Sprague-Dawley , Fatores de Tempo
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