RESUMO
AIMS: There have been many reports of monoamine oxidase (MAO) inhibition by non-nicotine ingredients in tobacco smoke, persisting for days after smoking cessation. This study determined the effect of inhibiting MAO and its isoforms on nicotine withdrawal syndrome. MAIN METHODS: Rats were rendered nicotine-dependent by seven days of subcutaneous (s.c.) 9 mg/kg/day infusion of nicotine bitartrate. Twenty-two hours after termination of infusion, they were observed over 20 min for somatically expressed nicotine withdrawal signs. Three hours before observation, rats were injected intraperitoneally (i.p.) with 4 mg/kg each of the MAO A antagonist clorgyline and the MAO B antagonist deprenyl, or with saline alone. A similar experiment was performed with non-dependent, saline-infused rats. Another experiment compared nicotine-dependent rats that received injections of either saline or 4 mg/kg clorgyline alone. A further experiment compared rats receiving either saline or 4 mg/kg deprenyl alone. KEY FINDINGS: Combined treatment with both MAO inhibitors markedly and significantly exacerbated somatically expressed nicotine withdrawal signs in nicotine infused rats, while having no significant effects in saline-infused rats. Rats injected s.c. with 4 mg/kg clorgyline alone had significantly more withdrawal signs than saline-injected rats, while deprenyl-injected rats had significantly fewer signs than saline controls. Assays confirmed that clorgyline thoroughly reduced MAO A enzymatic activity and deprenyl thoroughly reduced MAO B activity. SIGNIFICANCE: The results suggest that inhibition of MAO A may contribute to the intensity of withdrawal syndrome in smoking cessation.
Assuntos
Clorgilina/administração & dosagem , Inibidores da Monoaminoxidase/administração & dosagem , Monoaminoxidase/metabolismo , Nicotina/efeitos adversos , Selegilina/administração & dosagem , Síndrome de Abstinência a Substâncias/tratamento farmacológico , Animais , Encéfalo/enzimologia , Avaliação Pré-Clínica de Medicamentos , Sinergismo Farmacológico , Quimioterapia Combinada , Isoenzimas/antagonistas & inibidores , Masculino , Ratos , Ratos Sprague-Dawley , Abandono do Hábito de Fumar , Síndrome de Abstinência a Substâncias/enzimologiaRESUMO
It has been proposed that rare variants within the double strand break repair genes CHEK2, BRIP1 and PALB2 predispose to breast cancer. The aim of this study was to evaluate the prevalence of these variants in an Irish breast cancer cohort and determine their contribution to the development of breast cancer in the west of Ireland. We evaluated the presence of CHEK2_1100delC variant in 903 breast cancer cases and 1,016 controls. Six previously described variants within BRIP1 and five within PALB2 were screened in 192 patients with early-onset or familial breast cancer. Where a variant was evident, it was then examined in the remainder of our 711 unselected breast cancer cases. CHEK2_1100delC was found in 5/903 (0.5%) breast cancer cases compared to 1/1016 (0.1%) controls. One mutation at BRIP1 (2392 C>T) was identified in the early-onset/familial cohort. Examination of this variant in the remainder of our cohort (711 cases) failed to identify any additional cases. None of the previously described PALB2 variants were demonstrated in the early-onset/familial cohort. We show evidence of CHEK2_1100delC and BRIP1 2392 C>T within the Irish population. CHEK2_1100delC and BRIP1 mutations incidence in Ireland is similar to that found in other unselected breast cancer cohorts from northern European countries. We found no evidence to suggest that PALB2 mutation is an important breast cancer predisposition gene in this population.
Assuntos
Neoplasias da Mama/genética , Proteínas de Ligação a DNA/genética , Predisposição Genética para Doença , Proteínas Nucleares/genética , Proteínas Serina-Treonina Quinases/genética , RNA Helicases/genética , Proteínas Supressoras de Tumor/genética , Adulto , Sequência de Bases , Quinase do Ponto de Checagem 2 , Estudos de Coortes , Proteína do Grupo de Complementação N da Anemia de Fanconi , Proteínas de Grupos de Complementação da Anemia de Fanconi , Feminino , Genótipo , Humanos , Irlanda , Pessoa de Meia-Idade , Dados de Sequência Molecular , Mutação , Reação em Cadeia da Polimerase , Polimorfismo de Nucleotídeo ÚnicoRESUMO
Hyperplastic Polyposis (HPPS) is a poorly characterized syndrome that increases colorectal cancer (CRC) risk. We aimed to provide a molecular classification of HPPS. We obtained 282 tumours from 32 putative HPPS patients with >or= 10 hyperplastic polyps (HPs); some patients also had adenomas and CRCs. We found no good evidence of microsatellite instability (MSI) in our samples. The epithelium of HPs was monoclonal. Somatic BRAF mutations occurred in two-thirds of our patients' HPs, and KRAS2 mutations in 10%; both mutations were more common in younger cases. The respective mutation frequencies in a set of 'sporadic' HPs were 18% and 10%. Importantly, the putative HPPS patients generally fell into two readily defined groups, one set whose polyps had BRAF mutations, and another set whose polyps had KRAS2 mutations. The most plausible explanation for this observation is that there exist different forms of inherited predisposition to HPPS, and that these determine whether polyps follow a BRAF or KRAS2 pathway. Most adenomas and CRCs from our putative HPPS patients had 'classical' morphology and few of these lesions had BRAF or KRAS2 mutations. These findings suggest that tumourigenesis in HPPS does not necessarily follow the 'serrated' pathway. Although current definitions of HPPS are sub-optimal, we suggest that diagnosis could benefit from molecular analysis. Specifically, testing BRAF and KRAS2 mutations, and perhaps MSI, in multiple polyps could help to distinguish HPPS from sporadic HPs. We propose a specific model which would have diagnosed five more of our cases as HPPS compared with the WHO clinical criteria.
Assuntos
Neoplasias Colorretais/genética , Polipose Intestinal/genética , Adolescente , Adulto , Idoso , Transformação Celular Neoplásica/genética , Criança , Neoplasias Colorretais/diagnóstico , Neoplasias Colorretais/patologia , Feminino , Predisposição Genética para Doença , Humanos , Hiperplasia/genética , Mucosa Intestinal/metabolismo , Polipose Intestinal/diagnóstico , Polipose Intestinal/patologia , Perda de Heterozigosidade , Masculino , Pessoa de Meia-Idade , Mutação , Proteínas de Neoplasias/genética , Fenótipo , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas B-raf/genética , Proteínas Proto-Oncogênicas p21(ras) , Proteínas ras/genéticaRESUMO
The nuclear-encoded Krebs cycle enzymes, fumarate hydratase (FH) and succinate dehydrogenase (SDHB, -C and -D), act as tumour suppressors. Germline mutations in FH predispose individuals to leiomyomas and renal cell cancer (HLRCC), whereas mutations in SDH cause paragangliomas and phaeochromocytomas (HPGL). In this study, we have shown that FH-deficient cells and tumours accumulate fumarate and, to a lesser extent, succinate. SDH-deficient tumours principally accumulate succinate. In situ analyses showed that these tumours also have over-expression of hypoxia-inducible factor 1alpha (HIF1alpha), activation of HIF1alphatargets (such as vascular endothelial growth factor) and high microvessel density. We found no evidence of increased reactive oxygen species in our cells. Our data provide in vivo evidence to support the hypothesis that increased succinate and/or fumarate causes stabilization of HIF1alpha a plausible mechanism, inhibition of HIF prolyl hydroxylases, has previously been suggested by in vitro studies. The basic mechanism of tumorigenesis in HPGL and HLRCC is likely to be pseudo-hypoxic drive, just as it is in von Hippel-Lindau syndrome.
Assuntos
Fumarato Hidratase/genética , Mutação em Linhagem Germinativa , Succinato Desidrogenase/genética , Succinato Desidrogenase/metabolismo , Carcinoma de Células Renais/metabolismo , Ciclo do Ácido Cítrico/fisiologia , Feminino , Fumarato Hidratase/metabolismo , Humanos , Leiomioma/genética , Leiomioma/metabolismo , Neoplasias/genética , Neoplasias/metabolismo , Paraganglioma/genética , Paraganglioma/metabolismo , Células Tumorais Cultivadas , Fator A de Crescimento do Endotélio Vascular/metabolismoRESUMO
Germline mutations of the fumarate hydratase (FH, fumarase) gene are found in the recessive FH deficiency syndrome and in dominantly inherited susceptibility to multiple cutaneous and uterine leiomyomatosis (MCUL). We have previously reported a number of germline FH mutations from MCUL patients. In this study, we report additional FH mutations in MCUL and FH deficiency patients. Mutations can readily be found in about 75% of MCUL cases and most cases of FH deficiency. Some of the more common FH mutations are probably derived from founding individuals. Protein-truncating FH mutations are functionally null alleles. Disease-associated missense FH changes map to highly conserved residues, mostly in or around the enzyme's active site or activation site; we predict that these mutations severely compromise enzyme function. The mutation spectra in FH deficiency and MCUL are similar, although in the latter mutations tend to occur earlier in the gene and, perhaps, are more likely to result in a truncated or absent protein. We have found that not all mutation-carrier parents of FH deficiency children have a strong predisposition to leiomyomata. We have confirmed that renal carcinoma is sometimes part of MCUL, as part of the variant hereditary leiomyomatosis and renal cancer (HLRCC) syndrome, and have shown that these cancers may have either type II papillary or collecting duct morphology. We have found no association between the type or site of FH mutation and any aspect of the MCUL phenotype. Biochemical assay for reduced FH functional activity in the germline of MCUL patients can indicate carriers of FH mutations with high sensitivity and specificity, and can detect reduced FH activity in some patients without detectable FH mutations. We conclude that MCUL is probably a genetically homogeneous tumour predisposition syndrome, primarily resulting from absent or severely reduced fumarase activity, with currently unknown functional consequences for the smooth muscle or kidney cell.
Assuntos
Fumarato Hidratase/genética , Neoplasias Renais/genética , Leiomiomatose/genética , Mutação , Neoplasias Cutâneas/genética , Neoplasias Uterinas/genética , Erros Inatos do Metabolismo dos Aminoácidos/genética , Sequência de Aminoácidos , Estabilidade Enzimática , Feminino , Fumarato Hidratase/química , Fumarato Hidratase/deficiência , Fumarato Hidratase/metabolismo , Predisposição Genética para Doença , Mutação em Linhagem Germinativa , Humanos , Neoplasias Renais/secundário , Leiomiomatose/patologia , Dados de Sequência Molecular , Conformação Proteica , Estabilidade de RNA , RNA Mensageiro/metabolismo , Homologia de Sequência de Aminoácidos , Neoplasias Cutâneas/patologia , Neoplasias Uterinas/patologiaRESUMO
Familial adenomatous polyposis (FAP) is a dominantly inherited colorectal tumor predisposition that results from germ-line mutations in the APC gene (chromosome 5q21). FAP shows substantial phenotypic variability: classical polyposis patients develop more than 100 colorectal adenomas, whereas those with attenuated polyposis (AAPC) have fewer than 100 adenomas. A further group of individuals, so-called "multiple" adenoma patients, have a phenotype like AAPC, with 3-99 polyps throughout the colorectum, but mostly have no demonstrable germ-line APC mutation. Routine mutation detection techniques fail to detect a pathogenic APC germ-line mutation in approximately 30% of patients with classical polyposis and 90% of those with AAPC/multiple adenomas. We have developed a real-time quantitative multiplex PCR assay to detect APC exon 14 deletions. When this technique was applied to a set of 60 classical polyposis and 143 AAPC/multiple adenoma patients with no apparent APC germ-line mutation, deletions were found exclusively in individuals with classical polyposis (7 of 60, 12%). Fine-mapping of the region suggested that the majority (6 of 7) of these deletions encompassed the entire APC locus, confirming that haploinsufficiency can result in a classical polyposis phenotype. Screening for germ-line deletions in APC mutation-negative individuals with classical polyposis seems warranted.
Assuntos
Proteína da Polipose Adenomatosa do Colo/genética , Polipose Adenomatosa do Colo/genética , Genes APC/fisiologia , Adenoma/genética , Neoplasias Colorretais/genética , Primers do DNA , Éxons , Deleção de Genes , Testes Genéticos/métodos , Humanos , Reação em Cadeia da Polimerase/métodosRESUMO
Dominant transmission of multiple uterine and cutaneous smooth-muscle tumors is seen in the disorder multiple leiomyomatosis (ML). We undertook a genomewide screen of 11 families segregating ML and found evidence for linkage to chromosome 1q42.3-q43 (maximum multipoint LOD score 5.40). Haplotype construction and analysis of recombinations permitted the minimal interval containing the locus, which we have designated "MCUL1," to be refined to an approximately 14-cM region flanked by markers D1S517 and D1S2842. Allelic-loss studies of tumors indicated that MCUL1 may act as a tumor suppressor. Identification of MCUL1 should have wide interest, since this gene may harbor low-penetrance variants predisposing to the common form of uterine fibroids and/or may undergo somatic mutation in sporadic leiomyomata.
Assuntos
Cromossomos Humanos Par 1/genética , Leiomiomatose/genética , Neoplasias Uterinas/genética , Mapeamento Cromossômico , Feminino , Genes Supressores de Tumor/genética , Marcadores Genéticos/genética , Predisposição Genética para Doença/genética , Haplótipos/genética , Humanos , Escore Lod , Perda de Heterozigosidade/genética , Masculino , Mutação/genética , Linhagem , Penetrância , Recombinação Genética/genética , SoftwareRESUMO
Mendelian tumour syndromes are caused by rare mutations, which usually lead to protein inactivation. Few studies have determined whether or not the same genes harbour other, more common variants, which might have a lower penetrance and/or cause mild disease, perhaps indistinguishable from sporadic disease and accounting for a considerable proportion of the unexplained inherited risk of tumours in the general population. Germline variants at the APC locus are excellent candidates for explaining why some individuals are predisposed to colorectal adenomas, but do not have the florid phenotype of familial adenomatous polyposis. We have screened 164 unrelated patients with 'multiple' (3-100) colorectal adenomas for germline variants throughout the APC gene, including promoter mutations. In addition to three Ashkenazi patients with I1307K, we found seven patients with the E1317Q variant. E1317Q is significantly associated with multiple colorectal adenomas (OR = 11. 17, 95% CI = 2.30-54.3, p < 0.001), accounting for approximately 4% of all patients with multiple colorectal adenomas. In addition, four patients with truncating APC variants in exon 9 or in the 3' part of the gene were identified. Germline APC variants account for approximately 10% of patients with multiple adenomas. Unidentified predisposition genes almost certainly exist. We argue that it is worthwhile to screen multiple adenoma patients for a restricted number of germline APC variants, namely the missense changes E1317Q and I1307K (if of Ashkenazi descent), and, if there is a family history of colorectal tumours, for truncating mutations 5' to exon 5, in exon 9 and 3' to codon 1580.
Assuntos
Adenoma/genética , Neoplasias Colorretais/genética , Genes APC , Mutação em Linhagem Germinativa , Polipose Adenomatosa do Colo/genética , Adolescente , Adulto , Análise Mutacional de DNA , Mutação da Fase de Leitura , Genes Supressores de Tumor , Humanos , Pessoa de Meia-Idade , Mutação de Sentido Incorreto , Reação em Cadeia da Polimerase , Polimorfismo Conformacional de Fita Simples , Deleção de SequênciaRESUMO
The CAG repeat in exon 1 of the androgen receptor (AR) genes has been postulated as both a susceptibility allele and phenotypic modifier in BRCA1-associated breast cancers. We have analysed this repeat in a set of 178 breast cancer cases who have been selected only for age of presentation at 65 years or less. No effect of repeat length on age of presentation was found and there was no association between repeat length and family history. In combination with the data from other workers, our findings suggest that the androgen receptor repeat does not act as a modifier gene or susceptibility locus outside the context of the hereditary breast/ovarian cancer syndrome.
Assuntos
Neoplasias da Mama/genética , Receptores Androgênicos/genética , Repetições de Trinucleotídeos/genética , Adulto , Idade de Início , Éxons , Feminino , Humanos , Pessoa de Meia-IdadeRESUMO
OBJECTIVE: To determine the prevalence of completed elective total hip replacements in a defined elderly population. DESIGN: Cross sectional postal questionnaire survey with additional data and validation from general practice and hospital records. SETTING: Six general practices in the English counties of Avon, Somerset, and Oxfordshire. SUBJECTS: A total of 7806 patients aged 65 years and over (94.7% response). RESULTS: The overall prevalence (95% confidence intervals) of elective total hip replacement was 5.3 (4.8,5.8)% Age and sex specific prevalences were 2.7 (2.0,3.5)% in men and 4.1 (3.3,4.9)% in women aged 65-74 years, and 5.2 (4.0,6.5)% in men and 8.8 (7.6,10.0)% in women aged 75 years and over. Of the 415 patients who had received elective total hip replacement, 28.2% had required bilateral surgery, 20% had received at least one operation privately, and 13% had required revision surgery. CONCLUSION: Our results show an increased level of satisfied demand for total hip replacement in elderly people compared with earlier estimates. The increasing prevalence of hip replacement is an indicator of increasing potential demand for revision procedures. Population based surveys are required to establish the level of unmet demand for primary procedures. Differences in past surgical activity may be important in interpreting the wide variation in current surgical rates.