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1.
Br J Dermatol ; 183(6): 1083-1093, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-32215911

RESUMO

BACKGROUND: Frontal fibrosing alopecia (FFA) is a scarring alopecia with unclear pathogenesis and a progressive course. The disease has a major impact on patients' quality of life and there is a lack of effective treatment to halt disease progression. METHODS: We profiled lesional and nonlesional scalp biopsies collected in 2017 from patients with FFA (n = 12) compared with scalp biopsies from patients with alopecia areata (AA) (n = 8) and controls (n = 8) to evaluate gene and protein expression, including the primary outcome (CXCL9). We determined significant differences between biomarkers using a two-sided Student's t-test adjusting P-values by false discovery rate. RESULTS: Significant increases were seen in CD8+ cytotoxic T cells, CD11c+ dendritic cells, CD103+ and CD69+ tissue-resident memory T cells in FFA and AA vs. control scalp (P < 0·05), with corresponding significantly upregulated granzyme B mRNA, particularly in FFA (P < 0·01). In AA, cellular infiltrates were primarily concentrated at the bulb, while in FFA these were mainly localized at the bulge. FFA demonstrated significant upregulation of T helper 1/intereferon (IFN) (IFN-γ, CXCL9/CXCL10), the Janus kinase/signal transducers and activators of transcription (JAK-STAT) pathway (STAT1, JAK3) and fibrosis-related products (vimentin, fibronectin; P < 0·05), with no concomitant downregulation of hair keratins and the T-regulatory marker, forkhead box P3, which were decreased in AA. The stem cell markers CD200 and K15 demonstrated significantly reduced expression only in FFA (P < 0·05). CONCLUSIONS: These data suggest that follicular damage and loss of stem cells in FFA may be mediated through immune attack in the bulge region, with secondary fibrosis and reduced but still detectable stem cells. JAK/STAT-targeting treatments may be able to prevent permanent follicular destruction and fibrosis in early disease stages.


Assuntos
Alopecia em Áreas , Líquen Plano , Alopecia , Humanos , Janus Quinase 3 , Qualidade de Vida , Couro Cabeludo
2.
Chem Commun (Camb) ; 53(63): 8894-8897, 2017 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-28740993

RESUMO

A combination of 'orthogonal' thiol-ene 'click' reactions is utilized for fabrication and functionalization of micro-patterned hydrogels. A furan-protected maleimide-containing parent copolymer is partially activated via the retro Diels-Alder reaction to obtain an 'orthogonally' functionalizable copolymer, where the different functional groups can be exploited for multi-functionalization or fabrication of functional hydrogels using combination of the nucleophilic and radical thiol-ene reactions.

3.
Int J Stroke ; 8 Suppl A100: 62-8, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23294913

RESUMO

INTRODUCTION: The UK National Stroke Strategy (Department of Health 2007) states that patients should have access to a stroke service with neurointerventional capacity. This survey was conducted by the Clinical Standards Committee of the British Association of Stroke Physicians to get a snapshot of the availability of interventional treatments for stroke in the United Kingdom. METHODS: Questionnaires covering availability of endovascular treatments for stroke, e.g. intra-arterial thrombolysis and mechanical thrombectomy, were emailed to all British Association of Stroke Physicians members in October 2010. Where more than one response was received from the same hospital, the data were only entered once. If there was a discrepancy between different respondents for the same hospital, details were cross-checked with the respondents to ensure accuracy. RESULTS: Responses were received from 58 hospitals in England, Scotland, Wales, and Northern Ireland. Intra-arterial thrombolysis and/or mechanical thrombectomy were available in 23 hospitals. Of these, three had not performed any procedures in 2010. Twenty centres had conducted a mean (range) of eight (2-20) procedures during the 10-month period. Thirty-five hospitals were not offering endovascular treatments. Sixteen of these were not referring patients to centres which could provide interventional treatments. Hospitals offering endovascular treatments had a mean (range) of 5.2 (2-12) stroke physicians, 2.3 (0-4) interventional neuroradiologists, and 3.6 (0-9) noninterventional neuroradiologists. Only two hospitals providing interventions had four or more interventional neuroradiologists. CONCLUSIONS: Only a small number of hospitals in the United Kingdom provide interventional treatments for stroke. Almost 50% of hospitals not providing interventions had no processes in place for referral to providers.


Assuntos
Acidente Vascular Cerebral/terapia , Terapia Trombolítica/estatística & dados numéricos , Revascularização Cerebral/estatística & dados numéricos , Atenção à Saúde/estatística & dados numéricos , Hospitais/estatística & dados numéricos , Humanos , Trombólise Mecânica/estatística & dados numéricos , Corpo Clínico Hospitalar/provisão & distribuição , Neurologia/estatística & dados numéricos , Radiografia/estatística & dados numéricos , Inquéritos e Questionários , Trombectomia/estatística & dados numéricos , Reino Unido
5.
Br J Radiol ; 79(946): e120-2, 2006 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16980665

RESUMO

Primary retroperitoneal teratoma is a rare entity in adults. It has a distinctive imaging appearance. We describe a case of a 22-year-old patient who was referred to our hospital with the complaint of abdominal distension. Radiological work-up disclosed a retroperitoneal teratoma. Laparotomy with tumour resection was performed. Pathological examination revealed a benign cystic teratoma. The patient is doing well at follow-up.


Assuntos
Doenças Raras/diagnóstico por imagem , Neoplasias Retroperitoneais/diagnóstico por imagem , Teratoma/diagnóstico por imagem , Adulto , Humanos , Masculino , Doenças Raras/cirurgia , Neoplasias Retroperitoneais/cirurgia , Teratoma/cirurgia , Tomografia Computadorizada por Raios X , Ultrassonografia
6.
Acta Radiol ; 47(6): 559-61, 2006 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-16875332

RESUMO

A left atrial aneurysm is a rare cardiac anomaly. The etiology is usually congenital, but it can also occur as an acquired pathology secondary to mitral valve disease or a degenerative process. We report a case which, on routine PA chest radiography, presented as cardiomegaly with a bulge on the left cardiac contour. Further evaluation by contrast-enhanced computed tomography proved it to be caused by a large left atrial aneurysm.


Assuntos
Meios de Contraste , Aneurisma Cardíaco/congênito , Átrios do Coração/anormalidades , Tomografia Computadorizada por Raios X , Adulto , Cardiomegalia/diagnóstico por imagem , Diagnóstico Diferencial , Aneurisma Cardíaco/diagnóstico por imagem , Átrios do Coração/diagnóstico por imagem , Humanos , Masculino , Pericárdio/diagnóstico por imagem , Radiografia Torácica
7.
Australas Radiol ; 50(4): 298-305, 2006 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16884413

RESUMO

Hydatid disease has characteristic imaging features on CT, which allow accurate preoperative diagnosis in most cases. However, when it occurs at unusual locations the diagnosis is often difficult, especially as the imaging appearance varies at different sites. In this article we have presented a pictorial review of the CT features of disease due to Echinococcus granulosus at various sites in the human body.


Assuntos
Equinococose/diagnóstico por imagem , Tomografia Computadorizada por Raios X/métodos , Animais , Humanos
8.
Br J Radiol ; 78(935): 1050-2, 2005 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16249609

RESUMO

Wandering spleen is a rare entity, in which the spleen is abnormally mobile due to its attachment by a long vascular pedicle. This long vascular pedicle predisposes it to various complications, the most common being torsion. Here, we present a case in which a wandering spleen in a young female was complicated by pseudocyst formation, and discuss the possible aetiology, pathogenesis, diagnosis and therapeutic implications of this extremely rare complication.


Assuntos
Cistos/etiologia , Baço Flutuante/complicações , Dor Abdominal/etiologia , Adulto , Cistos/diagnóstico , Feminino , Humanos , Esplenopatias/diagnóstico , Esplenopatias/etiologia , Tomografia Computadorizada por Raios X , Baço Flutuante/diagnóstico
9.
Am J Physiol Cell Physiol ; 283(3): C673-8, 2002 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-12176724

RESUMO

Experiments were carried out to study in vitro the effects of 17beta-estradiol (E(2)), homologous pituitary homogenate (HPH), and recombinant red sea bream growth hormone (sbGH) on vitellogenin (VTG) secretion from cultured sea bream liver fragments. Basal secretion of VTG was found to be significantly higher in the prespawning period, compared with sea bream liver in the spawning and postspawning periods. Similarly, the sea bream liver obtained during the prespawning period responded more significantly to treatments with E(2), HPH, or sbGH compared with sea bream liver during spawning. In the postspawning period, treatments with E(2), HPH, or sbGH were without significant effect on VTG secretion level in sea bream liver. The level of E(2) receptors was also analyzed by Western blot analysis. The result demonstrates a significantly higher level of E(2) receptors in the sea bream liver at the prespawning stage compared with those at the spawning and postspawning stages. The findings support the hypothesis that homologous upregulation of estrogen receptors plays an important role in the estrogen-sensitive control of VTG synthesis in the sea bream liver.


Assuntos
Hormônios/fisiologia , Fígado/metabolismo , Vitelogeninas/biossíntese , Animais , Western Blotting , Linhagem Celular , Meios de Cultivo Condicionados/química , Estradiol/farmacologia , Feminino , Hormônio do Crescimento/farmacologia , Hormônios/farmacologia , Humanos , Técnicas In Vitro , Fígado/efeitos dos fármacos , Hipófise/química , Hormônios Hipofisários/farmacologia , Receptores de Estradiol/análise , Receptores de Estradiol/metabolismo , Proteínas Recombinantes/farmacologia , Dourada , Estações do Ano , Extratos de Tecidos/farmacologia
11.
Gastroenterology ; 118(1): 192-6, 2000 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-10611168

RESUMO

Reports show that hepatopulmonary syndrome mostly occurs in the setting of advanced hepatic dysfunction, with the associated vasoactive substance imbalance believed to be responsible for its pathogenesis. However, hepatopulmonary syndrome has also been reported in cases of mild hepatic dysfunction or noncirrhotic portal hypertension, indicating that portal hypertension also plays a part in the pathogenesis. Liver transplantation remains the only therapeutic option of proven benefit. We describe 2 cases of hepatopulmonary syndrome in the setting of inferior vena cava (suprahepatic) obstruction, but with minimal hepatic dysfunction. After balloon cavoplasty, 1 patient showed, in addition to improvement of the features of hepatic outflow obstruction, significant reduction of dyspnea, cyanosis, and hypoxemia with arterial blood gas normalization within 2 weeks and intrapulmonary shunt reversal within 8 weeks. This implies that hemodynamic alterations (such as portal hypertension) independently contribute to the pathogenesis of hepatopulmonary syndrome in at least some of the cases. Therapies aimed at correcting these abnormal hemodynamics may be important in the treatment of this condition, especially when the hepatic functional status by itself does not warrant a liver transplant.


Assuntos
Angioplastia com Balão , Síndrome Hepatopulmonar/complicações , Síndrome Hepatopulmonar/terapia , Veia Cava Inferior , Adulto , Constrição Patológica/complicações , Constrição Patológica/terapia , Hemodinâmica , Síndrome Hepatopulmonar/fisiopatologia , Humanos , Masculino
12.
Mutagenesis ; 14(6): 533-40, 1999 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-10567027

RESUMO

In order to study the mutagenic effects of heterocyclic aromatic amines (HAAs) in cells of human origin, five compounds, namely 2-amino-3-methyl-imidazo[4,5-f]quinoline (IQ), 2-amino-3, 4-dimethyl-imidazo[4,5-f]quinoline (MeIQ), 2-amino-3, 8-dimethyl-imidazo[4,5-f]quinoxaline (MeIQx), the pyridoimidazo derivative 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1), were tested in micronucleus (MN) assays with a human derived hepatoma (HepG2) cell line. All HAAs caused significant, dose-dependent effects. The activities of IQ, MeIQ, MeIQx and PhIP were similar (lowest effective concentrations 25-50 microM), whereas Trp-P-1 was effective at a dose of >/=2.1 microM. In addition, the HAAs were tested in MN assays with Chinese hamster ovary (CHO) cells and in Salmonella strain YG1024 using HepG2 cell homogenates as an activation mix. In the CHO experiments, positive results were obtained with Trp-P-1 and PhIP, whereas the other compounds were devoid of activity under all experimental conditions. The discrepancy in the responsivity of the two cell lines is probably due to differences in their acetylation capacity: enzyme measurements with 2-aminofluorene as a substrate revealed that the cytosolic acetyltransferase activity in the HepG2 cells is approximately 40-fold higher than that of the CHO cells. In the bacterial assays all five HAAs gave positive results but the ranking order was completely different from that seen in the HepG2/MN experiments (IQ > MeIQ > Trp-P-1 >/= MeIQx >> PhIP) and the mutagenic potencies of the various compounds varied over several orders of magnitude. The order obtained in bacterial tests with rat liver S9 mix was more or less identical to that seen in the tests with HepG2 cell homogenates but the concentrations of the amines required to give positive results were in general substantially lower (10(-5)-10(-1) microM). Overall, the results of the present study indicate that MN/HepG2 tests might reflect the mutagenic effects of HAAs more adequately than other in vitro mammalian cell systems due to the presence of enzymes involved in the metabolic conversion of the amines.


Assuntos
Aminas/toxicidade , Compostos Heterocíclicos/toxicidade , Mutagênicos/toxicidade , Animais , Arilamina N-Acetiltransferase/metabolismo , Células CHO/efeitos dos fármacos , Células CHO/enzimologia , Carbolinas/toxicidade , Carcinógenos/toxicidade , Carcinoma Hepatocelular/enzimologia , Carcinoma Hepatocelular/metabolismo , Linhagem Celular , Sobrevivência Celular , Cricetinae , Humanos , Imidazóis/toxicidade , Neoplasias Hepáticas/enzimologia , Neoplasias Hepáticas/metabolismo , Testes de Mutagenicidade , Quinolinas/toxicidade , Quinoxalinas/toxicidade , Ratos , Salmonella/efeitos dos fármacos , Salmonella/genética , Salmonella/crescimento & desenvolvimento , Células Tumorais Cultivadas
13.
J Environ Pathol Toxicol Oncol ; 18(2): 109-18, 1999.
Artigo em Inglês | MEDLINE | ID: mdl-15281222

RESUMO

Over the past decades, strong efforts have been made to identify dietary constituents that protect against the genotoxic effects of heterocyclic aromatic amines (HAAs). However, most of the methods that have been used, in particular in vitro assays that require the addition of exogenous enzyme homogenates, have only a limited predictive value because important protective mechanisms are not adequately represented and may give misleading results. Therefore, we attempted to develop improved test systems, namely assays, with human hepatoma cells and single-cell gel electrophoresis (SCGE) tests with rats. Genotoxicity tests with human derived Hep G2 cells reflect the genotoxic effects of HAAs better than other in vitro systems. They also enable the detection of protective effects since the human derived hepatoma cells possess phase I and phase II enzymes that are involved in the activation/ detoxification of the amines. The most appropriate endpoint for experiments with Hep G2 cells appears to be micronucleus induction, but protocols for other endpoints are available as well. The second promising model is the SCGE ("comet") assay with rats that was used successfully to measure protective effects of constituents of cruciferous vegetables against 2-amino-3-methylimidazo[4,5-flquinoline (IQ) in the liver and in the colon mucosa. The present study describes the experimental design of the new approaches, as well as results obtained with various dietary constituents.


Assuntos
Antimutagênicos/farmacologia , Ensaio Cometa , Dano ao DNA/efeitos dos fármacos , Compostos Heterocíclicos/toxicidade , Extratos Vegetais/farmacologia , Verduras/química , Animais , Antimutagênicos/classificação , Carcinoma Hepatocelular/tratamento farmacológico , Carcinoma Hepatocelular/patologia , Linhagem Celular Tumoral , Quimioprevenção , Dieta , Humanos , Extratos Vegetais/classificação , Ratos
14.
Mol Biochem Parasitol ; 92(2): 195-206, 1998 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-9657325

RESUMO

To elucidate the role played by casein kinase II in Leishmania survival, we have isolated and characterized the Leishmania chagasi casein kinase II alpha subunit cDNA, (L.c CKIIalpha). The 1083 bp coding region is flanked by 148 bp of 5' UTR and 1155 bp of 3' UTR. L.c CKIIalpha shows a remarkable degree of similarity with other isolated casein kinase II alpha subunit sequences. L.c CKIIalpha protein is encoded by a single copy gene that transcribes a mRNA of 2.4 kb. The 41.2 kDa L.c CKIIalpha protein expressed in vitro has been shown to be catalytically active. A single allele disruption of the L.c CKIIalpha gene that removes 94 bp from the coding region which contains one of the 15 conserved amino acids closest to the carboxy-terminus of the protein has been generated. This mutant is viable and results in a reduction of L.c CKIIalpha transcript levels over 14-fold and that of an iron superoxide dismutase mRNA by 5-fold. As well, the kinase activity of the single allele disrupted cells showed a 3-fold reduction as compared to the wild type cells suggesting a decrease in activity of the L.c CkIIalpha enzyme.


Assuntos
Cinamatos , Leishmania/enzimologia , Leishmania/genética , Proteínas Serina-Treonina Quinases/genética , Alelos , Sequência de Aminoácidos , Animais , Antibacterianos/farmacologia , Northern Blotting , Southern Blotting , Caseína Quinase II , DNA Complementar/análise , Ativação Enzimática , Regulação da Expressão Gênica , Higromicina B/análogos & derivados , Higromicina B/farmacologia , Técnicas In Vitro , Leishmania/crescimento & desenvolvimento , Dados de Sequência Molecular , Mutagênese , Reação em Cadeia da Polimerase , Proteínas Serina-Treonina Quinases/isolamento & purificação , Proteínas Serina-Treonina Quinases/fisiologia , RNA Mensageiro/metabolismo , Análise de Sequência de DNA , Homologia de Sequência de Aminoácidos
15.
Mutat Res ; 402(1-2): 185-202, 1998 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-9675276

RESUMO

The human hepatoma line (Hep G2) has retained the activities of various phase I and phase II enzymes which play a crucial role in the activation/detoxification of genotoxic procarcinogens and reflect the metabolism of such compounds in vivo better than experimental models with metabolically incompetent cells and exogenous activation mixtures. In the last years, methodologies have been developed which enable the detection of genotoxic effects in Hep G2 cells. Appropriate endpoints are the induction of 6-TGr mutants, of micronuclei and of comets (single cell gel electrophoresis assay). It has been demonstrated that various classes of environmental carcinogens such as nitrosamines, aflatoxins, aromatic and heterocyclic amines and polycyclic aromatic hydrocarbons can be detected in genotoxicity assays with Hep G2 cells. Furthermore, it has been shown that these assays can distinguish between structurally related carcinogens and non-carcinogens, and positive results have been obtained with rodent carcinogens (such as safrole and hexamethylphosphoramide) which give false negative results in conventional in vitro assays with rat liver homogenates. Hep G2 cells have also been used in antimutagenicity studies and can identify mechanisms not detected in conventional in vitro systems such as induction of detoxifying enzymes, inactivation of endogenously formed DNA-reactive metabolites and intracellular inhibition of activating enzymes.


Assuntos
Antimutagênicos/farmacologia , Carcinoma Hepatocelular/metabolismo , Neoplasias Hepáticas/metabolismo , Mutagênicos/toxicidade , Animais , Carcinoma Hepatocelular/enzimologia , Carcinoma Hepatocelular/patologia , Humanos , Neoplasias Hepáticas/enzimologia , Neoplasias Hepáticas/patologia , Testes de Mutagenicidade , Células Tumorais Cultivadas
16.
Am J Cardiol ; 80(3): 372-6, 1997 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-9264444

RESUMO

The diagnosis and site of graft dehiscence determined by transesophageal echocardiography (TEE), transthoracic echocardiography (TTE), and aortography in 6 patients, and by computed tomography (CT) scan in 3 patients were compared with surgery. Sensitivity of TEE was 100%, aortography 83%, CT scan 67%, and TTE 33%; TEE accurately identified severe aortic regurgitation (3), graft narrowing (2), distal aortic dissection (1), and a fistulous communication between the aortic root and the right ventricle (1) when compared with surgery or aortography.


Assuntos
Ecocardiografia Transesofagiana , Próteses Valvulares Cardíacas , Complicações Pós-Operatórias/diagnóstico por imagem , Adulto , Falso Aneurisma/diagnóstico por imagem , Aneurisma Aórtico/diagnóstico por imagem , Insuficiência da Valva Aórtica/diagnóstico por imagem , Aortografia , Ecocardiografia Doppler em Cores , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Reoperação , Tomografia Computadorizada por Raios X
17.
Mutagenesis ; 12(4): 297-303, 1997 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-9237777

RESUMO

The effects of dietary bioantimutagens (compounds which have been shown to inhibit mutagenesis via interaction with DNA repair processes) on spontaneous and heterocyclic amine (HCA)-induced micronucleus (MN) frequencies were studied in metabolically competent human hepatoma (Hep-G2) cells. All the compounds tested (coumarin, vanillin, caffeine, tannic acid and cinnamaldehyde) caused a moderate increase of MN numbers in Hep-G2 cells at high concentrations (500 microg/ml); only tannic acid was also active at lower dose levels. In combination experiments with the HCA 2-amino-3-methylimidazo-[3,4-f]quinoline (IQ), post-treatment of the cells with bioantimutagens resulted in a pronounced (75-90%) decrease in MN. The most drastic effects were seen with vanillin, coumarin and caffeine which were active at concentrations < or = 5 microg/ml. Further experiments indicated that these compounds also attenuate the mutagenic effects of other HCAs (PhIP, MeIQ, MeIQx, Trp-P-1).


Assuntos
Aminas/toxicidade , Antimutagênicos/farmacologia , Carcinoma Hepatocelular/tratamento farmacológico , Carcinoma Hepatocelular/genética , Compostos Heterocíclicos/toxicidade , Acroleína/análogos & derivados , Acroleína/farmacologia , Benzaldeídos/farmacologia , Cafeína/farmacologia , Carbolinas/toxicidade , Cumarínicos/farmacologia , Reparo do DNA/efeitos dos fármacos , Humanos , Taninos Hidrolisáveis/farmacologia , Imidazóis/toxicidade , Testes para Micronúcleos , Mutagênicos/toxicidade , Quinolinas/toxicidade , Células Tumorais Cultivadas
18.
Am J Cardiol ; 79(4): 436-41, 1997 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-9052346

RESUMO

The aim of the study was to compare the accuracy of multiplane transesophageal echocardiography (TEE) with the more conventional biplane technique in the direct assessment of aortic valve area in patients with aortic stenosis. Short-axis images of the aortic valve adequate for measuring aortic valve area were obtained in all 81 patients studied by multiplane TEE but in only 56 of 64 patients (88%) using the biplane approach. The correlation coefficient for aortic valve area determined by multiplane TEE (r = 0.89; SEE = 0.04 cm2) was higher (p < 0.01) than biplane TEE (r = 0.74; SEE = 0.06 cm2). Correlations were higher for bicuspid valves (multiplane, r = 0.93; biplane, r = 0.75) than tricuspid valves (multiplane, r = 0.87; biplane, r = 0.75). Our study has demonstrated the superiority of multiplane TEE to both biplane TEE and transthoracic echocardiography (TTE) in the direct evaluation of aortic valve area in patients with aortic stenosis.


Assuntos
Estenose da Valva Aórtica/diagnóstico , Ecocardiografia Transesofagiana/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
19.
Mutat Res ; 350(1): 93-102, 1996 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-8657203

RESUMO

Phenethyl isothiocyanate (PEITC), a constituent of cruciferous vegetables, inhibited the genotoxic effects of N-nitrosodimethylamine (DMN) and of 2-amino-1-methyl-6-phenylimidazo[4,5-beta]pyridine (PhIP) in differential DNA repair assays with E. coli K-12 strains in vitro and in animal mediated assays with mice. In Salmonella typhimurium, the mutagenic activities of DMN and PhIP measured after activation with S-9 homogenates from several organs of PEITC-treated mice were substantially lower than those obtained with homogenates of untreated animals as well. PEITC also reduced the formation of micronuclei by DMN in metabolically competent Hep-G-2 cells of human origin but was ineffective in combination with PhIP. Biochemical investigations showed that the prevention of genotoxic effects of DMN by PEITC results form an inhibition of its alpha-hydroxylation. The effect of oral administration of PEITC on the formation of DNA adducts of PhIP was examined in the colon and liver of mice. No inhibition of adduct formation was observed in these experiments. Biochemical experiments showed that PEITC reduces not only the metabolic activation of PhIP via 2-hydroxyamino PhIP but also inhibits a detoxification pathway (formation of 4-hydroxy PhIP). The present results can be taken as an indication that the anticarcinogenic activities of isothiocyanates towards nitrosamines are paralleled by antimutagenic effects, and that probably no such protective effects occur in combination with heterocyclic amines. Furthermore, our findings show that the effects of chemopreventive agents demonstrated in bacteria in vitro cannot always be extrapolated to reactions occurring in intact mammalian cells.


Assuntos
Antimutagênicos/farmacologia , Dimetilnitrosamina/toxicidade , Imidazóis/toxicidade , Isotiocianatos/farmacologia , Mutagênicos/toxicidade , Animais , Biotransformação , Carcinoma Hepatocelular , Adutos de DNA/metabolismo , Reparo do DNA/genética , Dimetilnitrosamina/metabolismo , Escherichia coli/efeitos dos fármacos , Escherichia coli/genética , Humanos , Hidroxilação/efeitos dos fármacos , Imidazóis/metabolismo , Camundongos , Microssomos Hepáticos/metabolismo , Testes de Mutagenicidade , Salmonella typhimurium/efeitos dos fármacos , Salmonella typhimurium/genética , Células Tumorais Cultivadas
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