ISSN:0959-8278    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

The large bowel is one of the major sites of cancer incidence and mortality in most western countries. In early studies most effort was expended in trying to find the causal factor, but the direction changed when Burkitt and Walker promoted the idea that the cancer could be prevented by dietary fibre (DF). Early studies to try to confirm this hypothesis were hampered by problems concerning the definition of DF, and the lack of good analytical methods to quantitate its intake. There was, however, general agreement that DF is a complex carbohydrate of plant origin that escapes small bowel digestion and so reaches the colon. It was assumed that the major plant polysaccharide, starch, is completely digested in the small bowel, but this is not true. Thus, the identity of DF as non-starch polysaccharide is not true, and other evidence suggests that it accounts for only about 25% of the true intake of DF. Assay of resistant starch' is fraught with difficulty and so it is better at this stage to use fibre-rich foods rather than inaccurate assays of DF in epidemiological studies. In this review, I have re-examined the epidemiological literature and have found that, whereas there could be dispute over the strength of the protection given by DF, there is no doubt about the protection afforded by cereal fibre. A further analysis of data from Europe, North America and Australasia shows that of the fibre-rich foods, cereals are strongly protective, as are vegetables: fruits are neutral, while starchy root vegetables, if anything, promote colorectal cancer.

ISSN:0959-8278    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Based on recent analytical data, total human exoenous exposure toN-nitrosamines is estimated to be 1.10 μmol/day: the major exposure sources are the diet (0.79 μmol/day, 80–120 μg/day; 72%), occupational exposure (0.15–0.30 μmol/day; 25%), cigarette smoking (0.02 μmol/day, 3.4 μg/day; 2%), and miscellaneous minor sources, including pharmaceutical products, cosmetics, indoor and outdoor air (0.001 μmol/day, 0.1 μg/day; 1%). Excretion of apparent totalN-nitroso compounds (ATNC) in healthy adults is estimated to be 1.30 ± 1.05 μmol/day in urine and between 1.56 ± 1.56 and 3.17 ± 2.58 μmol/day in faeces. The excretion of volatileN-nitrososarcosine, (N-nitrosodimethylamine), andN-nitrosamino acids and their derivatives (N-nitrososarcosine,N-nitrosoproline,N-nitrosothiazolidine-4-carboxylic acid andN-nitroso-2-methylthiazolidine-4-carboxylic acid) accounts for approximately 0.03% and 16.0% of urinary ATNC, respectively. 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanol and itsO-glucuronide conjugate, two metabolites of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone present in urine of smokers, account for 0.2% of the urinary ATNC response; > 1.5% of the excretion of currently identifiedN-nitroso compounds in urine. The remainingN-nitroso compounds excreted in urine and those present in faeces are still unidentified. A crude mass balance between exogenous exposure and excretion in urine and faeces indicates that 45–75% of the total human exposure toN-nitroso compounds results throughin vivoformation.

ISSN:0959-8278    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

It is proposed that the prerequisites for a low risk to major cancers - breast, colon, lung, prostate, melanoma (as, for example in Africans, Chinese and Japanese) - include upregulated hypothalamic dopamingergic activity compared to depressed noradrenergic/thyrogenic function and raised vagal tone, and a neuroendocrine constellation that promotes improved immune efficiency and is inimical to the onset of aversive cell responses. Since the integrity of these tissues is regulated by hypothalamic-hypophyseal hormones, under tonic dopaminergic inhibition, cancers are potentially preventable as long as dopaminergic integrity is maintained, or the decline in ageing is slowed. Evidence for the impact of upregulated dopamine on tumour prevention includes: (1) a reduced (40%) rate of colonic cancer in exercise-trained ageing subjects: (2) reduced expected rates of lung/colon cancers, and skin tumours in prolonged post-menopausal oestrogen replacement; (3) the virtual suppression of all cancers during pregnancy (when dopamine synthesis increases); (4) the low rate of bronchogenic carcinoma correlates with reduced enzymatic conversion of dopamine to noradrenaline; and (5) neuroblastoma (specifically dopamine dysregulated tumour) regresses spontaneously on dopamine normalization. Similar tumour reduction is anticipated by controlling the intake of calories. The subtlety of the switch to upregulated dopamine, the speed of translation at the cellular level and the sustainability of responses as long as the initiating stimulus persists (as exposed by pregnancy), underline the plasticity of the neuroendocrine mechanism and ease of manipulation. Long exposure to environmental iodine deficiency, as seen for example in Africans and Chinese, reveals a crucial dopamine-thyroid action that slows cell timing mechanisms. The common neurohormonal basis identified for the prevention of human cancers has practical application, with reasonably assured positive results.

ISSN:0959-8278    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

In order to assess the comparability and reproducibility of information from a questionnaire used in a case-control study on digestive tract cancers conducted in Italy, a total of 400 subjects were randomly selected from a large sample of hospital controls and contacted at home to repeat the interview. Of these, 294 (73%) subjects were re-interviewed. Mean values of intake were computed for the 400 subjects selected, and among the 294 responders for the first and second interview. These values were comparable, most of them being within a 10% range. Spearman correlation coefficient (r,) values of consumption between the first and second interview were < 0.65 for consumption of pastries, pasta or rice, bread, fish, milk, green vegetables, eggs and apples; between 0.50 and 0.65 for meat, chicken, liver, ham, cold cuts, cheese, fruit, cabbage, carrots, tomatoes, peppers, salad, citrus fruit and melon; and lower than 0.50 for a few infrequently eaten foods. For all foods, the estimated average weekly intake in the second interview increased consistently and substantially with increasing tertile of the first interview. This study shows a satisfactory comparability of dietary information from subjects interviewed at home with that provided during their original interview in the hospital, and a good reproducibility of information collected in the two settings.

ISSN:0959-8278    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

The use of biomarkers is a promising approach to the study of human cancer risk. Bronchial metaplasia in sputum cytology may be a marker for potential premalignancy that can be used for population studies. We recently performed a randomized, blinded, controlled trial in smokers on the effect of 14 weeks β-carotene (20 mg/day) on markers for DNA damage. We now have evaluated the application of sputum cytology in this study and performed a preliminary evaluation of the effect of β-carotene. Of the 150 potential participants in this trial 75 were not eligible because they failed to produce sputum samples (n= 29), or because samples were unsatisfactory (n= 46). The eligible group was older (41vs37 years) and had smoked longer (23vs19 years), but had similar cigarette consumption (mean 21/day) and plasma cotinine levels. Metaplasia was graded in seven categories. Only 11 subjects (15%) showed minor or mild atypia on study entry. Agreement within and between observers was 95% within the same or an adjacent category. We observed no significant correlation between before and after treatment final metaplasia scores in either the β-carotene (SpearmanR= 0.18,P= 0.3) or placebo group (SpearmanR= 0.17,P= 0.3). Initial metaplasia scores were somewhat higher in the β-carotene group (n= 33) than in the placebo group (n= 42) (P= 0.06). Final metaplasia scores were similar in both groups (P= 0.69), and there was no decrease in metaplasia scores in the β-carotene group (P= 0.75). This study indicates that sputum cytology may not yet be a readily applicable marker in studies of a healthy asymptomatic population, because many smokers do not spontaneously produce sputum, more severe lesions are rare, and variation over time in the minor lesions is large. Therefore. the preliminary evidence that β-carotene has no influence should be interpreted with care.

ISSN:0959-8278    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Gastric antral forceps biopsies taken at gastroscopy were cultured forHelicobacter pyloriand tested for anti-microbial sensitivity. Using micro-aerophilic culture, and disc testing or E-testing, there was 98–100% sensitivity to amoxycillin, tetracycline, clarithromycin and erythromycin. However, there was apparent resistance to metronidazole in 19 of 102 samples (19%). When sensitivity by E-testing was performed with preliminary anaerobic culture for 24 h only two of 94 samples (2%) showed resistance. In 37 cultures both micro-aerophilic disc testing and anaerobic then micro-aerophilic E-testing were conducted. Eight cultures showed resistance upon disc testing (MIC < 5 mg/1) but all of these organisms were sensitive on E-testing (MIC 0.003–0.5 mg/1). Metronidazole may be used with confidence in eradication regimes

ISSN:0959-8278    

出版商:OVID    

年代:1997

数据来源: OVID

ISSN:0959-8278    

出版商:OVID    

年代:1997

数据来源: OVID

ISSN:0959-8278    

出版商:OVID    

年代:1997

数据来源: OVID