Hormone replacement therapy and symptomatic gallstones - a prospective population study in the EPIC-Norfolk cohort

BACKGROUND/AIMS

Hormone replacement therapy (HRT) may increase the risk of symptomatic gallstones, but this association has not been investigated in a prospective study in a European population. The aim of the study was to investigate the relationship between HRT and the development of symptomatic gallstones in a free-living population.

METHODS

Use of HRT was ascertained by questionnaire in 13,433 women aged 45-74 years living in Norfolk, UK, who participated in the EPIC-Norfolk Study (European Prospective Investigation Into Cancer). The use of HRT was that at the time of recruitment rather than at the point of diagnosis. Participants were followed up for the development of symptomatic gallstones. The analysis used a nested case-control method in a prospective study.

RESULTS

A total of 117 women developed symptomatic gallstones. Women who reported either ever using HRT, currently using HRT or who had been past users all had a greater risk of gallbladder disease than age-matched control women who had never used HRT, after adjusting for known risk factors for gallstones. Women who had ever used HRT had a risk of 1.94 (95% CI = 1.17-3.22) compared with women who had never used HRT. For past users of HRT, the risk of symptomatic gallstones was greater, the longer the duration of use (OR = 4.05, 95% CI = 1.12-14.76 for use >1 year, compared to OR = 2.04, 95% CI = 0.79-5.30 for < or =1 year).

CONCLUSIONS

Use of HRT was positively associated with an increased risk of symptomatic gallstones in this population. This confirms trial data and additionally shows effects of duration of use and increased risk associated with past use.

Diet in the aetiology of ulcerative colitis: a European prospective cohort study

BACKGROUND/AIMS

The causes of ulcerative colitis are unknown, although it is plausible that dietary factors are involved. Case-control studies of diet and ulcerative colitis are subject to recall biases. The aim of this study was to examine the prospective relationship between the intake of nutrients and the development of ulcerative colitis in a cohort study.

METHODS

The study population was 260,686 men and women aged 20-80 years, participating in a large European prospective cohort study (EPIC). Participants were residents in the UK, Sweden, Denmark, Germany or Italy. Information on diet was supplied and the subjects were followed up for the development of ulcerative colitis. Each incident case was matched with four controls and dietary variables were divided into quartiles.

RESULTS

A total of 139 subjects with incident ulcerative colitis were identified. No dietary associations were detected, apart from a marginally significant positive association with an increasing percentage intake of energy from total polyunsaturated fatty acids (trend across quartiles OR = 1.19 (95% CI = 0.99-1.43) p = 0.07).

CONCLUSIONS

No associations between ulcerative colitis and diet were detected, apart from a possible increased risk with a higher total polyunsaturated fatty acid intake. A biological mechanism exists in that polyunsaturated fatty acids are metabolised to pro-inflammatory mediators.

Incidence of perforated diverticulitis and risk factors for death in a UK population

Background

Perforated diverticulitis (PD) remains a serious acute abdominal condition. The aims of this study were to measure its incidence in a large UK population and to identify factors affecting outcomes.

Methods

Computerized searches of hospital coding databases for PD were performed in five hospitals in East Anglia, UK. Data were collected from hospital records over 5 years (1995–2000). Incidence was calculated using population data, and factors associated with mortality and morbidity were identified using univariable and multivariable testing.

Results

Some 202 patients with PD were identified, of whom 93·1 per cent underwent surgery and 24·3 per cent died. The age-adjusted adult incidence of perforation was 3·5 per 100 000 per annum, with a standardized female to male ratio of 1·3 (95 per cent confidence interval (c.i.) 1·1 to 1·5) to 1. Risk factors for death were increased age (odds ratio (OR) 3·5 (95 per cent c.i. 1·9 to 6·1)), pre-existing renal disease (OR 18·7 (1·6 to 211·4)) and pre-existing use of non-steroidal anti-inflammatory drugs (NSAIDs) (OR 3·1 (1·3 to 7·3)).

Conclusion

PD is uncommon, with the highest incidence in women over 65 years old. Mortality rates are high, particularly in those taking NSAIDs or with pre-existing renal impairment.

Development of a food frequency questionnaire for the assessment of quercetin and naringenin intake

OBJECTIVES

To measure the relationship between quercetin and naringenin intakes as estimated by food frequency questionnaire (FFQ), and the urinary excretion of quercetin and naringenin aglycones after their enzymatic hydrolysis in human volunteers.

SUBJECTS AND METHODS

Volunteers were recruited via the Human Nutrition Unit volunteer databank at the Institute of Food Research, Norwich. Sixty-three volunteers were recruited into the study, of which 14 were excluded and 49 completed the study. A modified FFQ was developed and used to estimate daily intake of quercetin and naringenin in 49 healthy volunteers who also provided five 24-h urine samples over a 2-week period. Urinary excretion of quercetin and naringenin metabolites was determined by solid-phase extraction and high-pressure liquid chromatography.

RESULTS

The estimated mean intakes of quercetin and naringenin were 29.4 mg (s.d. 15.0) and 58.1 mg (s.d. 62.7) per day, respectively. Mean urinary excretion of quercetin was 60.1 microg (s.d. 33.1) and that of naringenin was 0.56 mg (s.d. 0.4). The correlation between FFQ estimated intake of quercetin and naringenin and levels excreted in the urine were r=0.82 (P<0.0001) and r=0.25 (P=0.05), respectively.

CONCLUSIONS

We observed a statistically significant correlation between the urinary excretion of quercetin and naringenin metabolites and their dietary intake as estimated by FFQ. Use of FFQs in epidemiological studies requiring an estimate of flavonoid intake seems justified.

A case-control study of drinking water and dairy products in Crohn's Disease--further investigation of the possible role of Mycobacterium avium paratuberculosis

Similarities between Johne's disease in ruminants and Crohn's disease in humans have led to speculation that Mycobacterium avium paratuberculosis (MAP) might be a causative agent in Crohn's disease. However, evidence remains inconsistent. In this case-control study (1999-2004), the authors assessed the possible role of drinking water and dairy products potentially contaminated with MAP in the etiology of Crohn's disease. A total of 218 patients with Crohn's disease recruited from nine hospitals in England and 812 controls recruited from the community completed a short questionnaire for evaluation of proxy measures of potential exposure to MAP. Logistic regression showed no significant association with measures of potential contamination of water sources with MAP, water intake, or water treatment. Multivariate analysis showed that consumption of pasteurized milk (per kg/month: odds ratio (OR) = 0.82, 95% confidence interval (CI): 0.69, 0.97) was associated with a reduced risk of Crohn's disease. Meat intake (per kg/month: OR = 1.40, 95% CI: 1.17, 1.67) was associated with a significantly increased risk of Crohn's disease, whereas fruit consumption (per kg/month: OR = 0.78, 95% CI: 0.67, 0.92) was associated with reduced risk. This study does not support a role for water or dairy products potentially contaminated with MAP in the etiology of Crohn's disease. The observed association with meat and the negative association with pasteurized milk need further study.

Non-steroidal anti-inflammatory drugs, lower oesophageal sphincter-relaxing drugs and oesophageal cancer. A case-control study

BACKGROUND AND AIMS

The incidence of oesophageal cancer has doubled in the last three decades. Non-steroidal anti-inflammatory drugs (NSAIDs) may be protective, whilst bronchodilators and calcium channel blockers that relax the lower oesophageal sphincter (LOS) may increase gastro-oesophageal reflux and the risk of oesophageal adenocarcinoma. We conducted a case-control study to examine the association between the use of NSAIDs and drugs which relax the LOS and the risk of oesophageal cancer.

METHODS

In Norfolk, 411 patients with a primary neoplasm of the oesophagus or cardia were matched with 1,644 controls with non-melanotic skin lesions. Data on the use of NSAIDs, bronchodilators and calcium channel blockers was collected.

RESULTS

Intake of NSAIDs was less in cases of oesophageal cancer as compared to the control group. The odds ratios (OR) and 95% confidence intervals (CI) for different NSAIDs were as follows: aspirin 0.35 (0.24-0.51); other NSAIDs 0.25 (0.16-0.40), and Cox-2 inhibitors 0.46 (0.20-0.94). LOS-relaxing drugs were consumed more frequently in cases of oesophageal cancer as compared to the controls. The OR for LOS-relaxing drugs was: inhaled bronchodilators 3.2 (95% CI 2.2-4.7); theophylline 1.9 (95% CI 1.3-5.1), and calcium channel blockers 2.4 (95% CI 1.2-5.0).

CONCLUSION

Within the limitations of a case-control study using patients with non-melanotic skin lesions as controls, our results are consistent with the hypothesis that oesophageal cancer has a negative association with NSAID use, and a positive association with drugs that relax the LOS.

An industry based approach to colorectal cancer screening in an asymptomatic population

The uptake of faecal occult blood testing in a workplace based colorectal cancer screening programme was investigated. Altogether 1828 employees aged 41-65 years at a large British industrial company were invited to receive a free faecal occult blood test (Haemoccult). Faecal occult blood tests were completed on three separate days. Patients with positive results were invited to undergo colonoscopy. The number of employees completing kits was measured and differences in compliance according to age, sex, and occupation were tested with a chi2 test. Compliance was 25.4%, and similar in men (25.0%) and women (32.0%, chi2=3.0, not significant). In men, compliance was highest in those aged 51-60 years (30.5% chi2>1.6, p<0.001). Compliance in women aged 41-50 years, 51-60 years, and 61-65 years was similar (Yates's corrected chi2<2.08, not significant). Managers returned more kits than clerical and blue collar workers (28.6% v 23.5%, chi2=5.6, p<0.02). One percent of tests were positive and one patient had a tubular adenoma. Compliance in employees aged 51-60 years was comparable to that achieved in one-off British general practice programmes, but less than that in the large randomised trial of screening in general practices in Nottinghamshire. Health education of large numbers of people is easier at the workplace than in the community. Future screening must target older employees and those with clerical and blue collar jobs.

Do calcium channel blockers and antimuscarinics protect against perforated colonic diverticular disease? A case control study

BACKGROUND

The aetiology of perforated colonic diverticular disease (PCDD) remains largely unknown. Perforation may result from a combination of high intracolonic pressures, secondary to excessive colonic segmentation, and impairment of the mucosal barrier. Calcium channel blockers and antimuscarinic drugs, which reduce colonic contractility and tone, could potentially protect against perforation. The aim of this study was to test this hypothesis using a case control design.

METHODS

All cases of acute PCDD were identified over a five year period in two hospitals in Norfolk, UK. Each case was matched for age, sex, and date of admission to two controls groups: (1) patients undergoing cataract surgery and (2) patients with basal cell carcinoma. Data on drug use prior to hospital admission were obtained from medical and nursing records and compared between cases and controls.

RESULTS

A total of 120 cases of PCDD were identified and matched to 240 controls in each group. A statistically significant protective association was seen between calcium channel blocker use and PCDD using both control groups. The odds ratios were 0.41 (95% confidence interval (CI) 0.18-0.93) using the ophthalmology control group and 0.36 (95% CI 0.16-0.82) using the dermatology control group.

CONCLUSIONS

This study has shown for the first time that a protective association exists between calcium channel blockers and PCDD. The validity of this association is supported by the consistent finding in both control groups and the plausible biological mechanisms. Further studies are required to confirm this association but calcium channel blockers may represent a potential preventive therapy in PCDD.

Anti-inflammatory drugs, analgesics and the risk of perforated colonic diverticular disease

BACKGROUND

Acute perforated colonic diverticular disease has a mortality rate of up to 30 per cent, but little is known about its aetiology. The aim of this study was to test the hypothesis that three classes of drugs, namely non-steroidal anti-inflammatory drugs (NSAIDs), opioid analgesics and corticosteroids, are risk factors for perforated diverticular disease.

METHODS

All patients with confirmed perforated colonic diverticular disease were identified over a 5-year period in two hospitals in Norfolk, UK. Two control groups were selected and matched for age, sex and hospital of admission. Data on medication use were obtained from hospital records. Odds ratios for each drug were calculated using conditional logistic regression.

RESULTS

Opioid analgesics, NSAIDs and corticosteroids were all positively associated with perforated colonic diverticular disease. The odds ratio for opioid analgesics was 1.8 (95 per cent confidence interval (c.i.) 1.1 to 3.0) in the analysis with ophthalmology controls and 3.1 (95 per cent c.i. 1.8 to 5.5) in that with dermatology controls. Respective odds ratios for NSAIDs were 4.0 (95 per cent c.i. 2.1 to 7.6) and 3.7 (95 per cent c.i. 2.0 to 6.8), and those for corticosteroids were 5.7 (95 per cent c.i. 2.2 to 14.4) and 7.8 (95 per cent c.i. 2.6 to 23.3).

CONCLUSION

Opioid analgesics, NSAIDs and corticosteroids are all positively associated with perforated colonic diverticular disease. The consistency of these associations, together with plausible biological mechanisms, suggests that these drugs may have a causative role in this condition.

Epidemiology of perforated colonic diverticular disease

Perforated colonic diverticular disease results in considerable mortality and morbidity. This review appraises existing evidence on the epidemiology and mechanisms of perforation, highlights areas of further study, and suggests an epidemiological approach towards preventing the condition. Computerised searches were used to identify published articles relating to the epidemiology, pathophysiology, and clinical features of perforated colonic diverticular disease. Several drug and dietary exposures have potential biological mechanisms for causing perforation. Of these only non-steroidal anti-inflammatory drugs have been consistently identified as risk factors in aetiological studies. The causes of perforated colonic diverticular disease remain largely unknown. Further aetiological studies, looking specifically at perforation, are required to investigate whether cause-effect relationships exist for both drug and dietary exposures. The identification of risk factors for perforation would allow primary public health prevention, secondary risk factor modification, and early prophylactic surgery to be aimed at people at high risk.

Epidemiology of duodenal ulcer perforation: a study on hospital admissions in Norfolk, United Kingdom

BACKGROUND

Studies on the incidence of perforated duodenal ulcer are limited and in the United Kingdom, data are largely based on findings observed over two decades ago. To provide updated epidemiological data on duodenal ulcer perforation, the incidence of the disease in Norfolk, United Kingdom was determined.

METHODOLOGY

Medical records of patients with duodenal ulcer perforation were reviewed to confirm the diagnosis and obtain information on possible risk factors, namely, Helicobacter pylori infection, smoking and intake of non-steroidal anti-inflammatory drugs. The patients were admitted between 1 January 1996 and 31 December 1998, and were residents of Norfolk, United Kingdom.

RESULTS

Sixty-eight cases of duodenal ulcer perforation were identified, 36 (52.9%) were males and 32 (47.1%) were females. The age-standardised incidence rate was 3.77 per 100,000 population per year (95% confidence interval 3.72-3.83). The mean age upon admission for all cases was 72.3 years (standard deviation: 17.8). The mean age for males was 67.7 years (standard deviation: 19.4) and for females 77.6 years (standard deviation: 15.7), which differed significantly (difference in means: 9.9, 95% confidence interval 1.5-18.3). There were 29 deaths (42.7%), of which 19 were females. After adjustment for covariates, the odds ratio of mortality in women was 4.57 (95% confidence interval 1.28-16.29). There were 25 (36.8%) smokers and 22 (32.4%) patients were non-steroidal anti-inflammatory drug users. Helicobacter pylori infection was assessed in only 14 (20.6%) patients; 2 were positive, 3 were negative, and in the rest the results were unrecorded.

CONCLUSIONS

The incidence rates were lower compared to previous studies in the United Kingdom conducted in the 1960's and 1980's, which could reflect either improved health care or decreasing exposure to known risk factors. Furthermore, the difference in age distribution of incident cases between males and females may explain the higher mortality in females.

Design of a multicentre randomised trial to evaluate flexible sigmoidoscopy in colorectal cancer screening

A randomised, controlled trial in progress in 14 United Kingdom and six Italian centres is evaluating screening for colorectal cancer using a single flexible sigmoidoscopy (FS) at around the age of 60 with removal during FS of all small adenomas, and colonoscopy for "high risk" polyps. The regimen aims to ensure that 95% of people (with either no polyps or only low risk polyps) complete the entire screening process in a single visit. This paper describes the rationale and design of the trial. Participants were patients aged between 55 and 64 on the lists of designated general practitioners (GPs) who were not excluded by their GP. A two stage recruitment procedure was employed to raise compliance rates in the intervention group. Potentially eligible persons were sent an "interest in screening" questionnaire; those who responded positively were randomised to the intervention or control groups. The trial is sufficiently large to estimate within narrow confidence intervals the magnitude of benefit and the duration of effect and optimum age for a single screen. It also examines the feasibility and acceptability of the screening regimen, and will identify training and quality assurance issues. Recruitment and screening are now complete and all baseline data have been collected. The first analysis of the effect on colorectal cancer incidence and mortality rates and suitability for a national screening programme can be expected in 2004.

National practice characteristics and utilization of pathologists' assistants

OBJECTIVE

To obtain descriptive information regarding the practice characteristics and utilization of US pathologists' assistants.

DESIGN

A self-administered, mailed, voluntary, anonymous questionnaire was distributed to a cross-sectional sample of 515 US pathologists' assistants registered as members of the American Association of Pathologists' Assistants. The questionnaire contained items relating to subject demographics, practice characteristics, specific task performance, and amount of time spent per day on the performance of specific tasks. Descriptive statistics were used to describe the data in terms of measures of central tendency and dispersion.

RESULTS

The response rate was 66.8%. The majority of questionnaires sent and received were from East Coast regions. Of all respondents, 46.6% were women, 57.6% were less than 40 years old, and 60.0% had been practicing 10 years or less. Over half (54.0%) had a master's degree. Almost the entire sample reported working 30 or more hours per week, with 43.4% reporting working more than 40 hours per week. The majority reported earning annual salaries between $56 000 and $75 000. Although task analysis of responses revealed a wide range of responses, the majority of the sample reported spending most of their daily time performing surgical specimen gross examinations (median 300 min/d). Approximately half of respondents also reported spending up to 90 minutes per day on nonspecific tasks such as logging specimens and answering the phone. Most respondents reported spending more daily time on such nonspecific tasks than on autopsy prosection or research.

CONCLUSIONS

To our knowledge, this national survey provides the first description of pathologists' assistants across the United States. These data provide a useful tool for tracking changes in the profession.

Clinical perception of disease probability associated with Bethesda System diagnoses

The degree to which clinical perceptions of Papanicolaou smear sensitivity contribute to patient mismanagement is uncertain. A voluntary, anonymous questionnaire was mailed to 350 obstetricians/gynecologists (OGYNs) and 350 other primary care providers (PCPs) located in Pennsylvania or Ohio. The clinicians estimated the probability of no disease, dysplasia, and invasive carcinoma for 1 of 7 Bethesda System diagnoses. Differences in probability estimates between provider types and between the clinicians and medical literature data were measured. The response rate was 22.7%. Compared with published values, clinicians estimated similar disease probabilities for many diagnoses. However, for some diagnoses, the probability estimates differed considerably from published values (e.g., overestimation of dysplasia and invasive carcinoma for benign diagnoses and underestimation of dysplasia for some dysplasia diagnoses), and such errors could contribute to patient mismanagement. OGYNs generally were more accurate in probability estimates than PCPs. Methods to convey more accurately these diagnostic disease probabilities should be examined.

Colonoscopic diagnosis and management of nonpolypoid early colorectal cancer

Nonpolypoid colorectal neoplasms are grossly classified into three groups: slightly elevated (small flat adenomas), laterally spreading, and depressed. Flat adenomas are not invasive until they are rather large, whereas depressed lesions can invade the submucosa even when they are extremely small. Nonpolypoid lesions are difficult to detect and are often overlooked. Keys to detect them are their slight color change, interruption of the capillary network pattern, slight deformation of the colonic wall, spontaneously bleeding spots, shape change of the lesion with insufflation and deflation of air, and interruption of the innominate grooves. Spraying of indigo carmine dye helps to clarify the lesions. A pit pattern analysis with a zoom colonoscope is useful for the diagnosis and staging of early colorectal cancer. Small flat adenomas are thought to be precursors of protruded polyps and lateral spreading tumors, whereas depressed lesions are thought to grow endophytically and become advanced cancers. Small depressed lesions are treated with an endoscopic mucosal resection (EMR) technique; but when they massively invade the submucosa, surgical resection is indicated. Laterally spreading tumors are not as invasive despite their large size and therefore are good indications for the EMR or piecemeal EMR method. Small flat adenomas need not be treated urgently, as almost none is invasive. Accurate diagnosis with dye-spraying and zoom colonoscopy is vital for deciding the treatment strategy.

How frequently do large bowel diverticula perforate? An incidence and cross-sectional study

The aetiology of perforation of large bowel diverticula is poorly understood and a case-control study is required to identify the causes. Before such a study can be attempted, the incidence must be determined and groups at particular risk identified. Cases of perforated large bowel diverticula living in the Norwich postal code region treated between 1995 and 1997 were identified. Fifty-eight cases presented in a population of 531 241. The incidence was 4.0 cases per 100,000 per year, increased with age and was higher in men than women (5.8 vs 3.1). The most frequently used drugs were non-steroidal anti-inflammatory drugs (NSAIDs) (29%) and opiate analgesics (26% of cases). This is the first report of the incidence of perforated diverticular disease and allows a calculation of the population size needed to recruit sufficient cases for an aetiological investigation. The differences in incidence between genders should prompt a search for factors which differ between the sexes such as diet. NSAIDs are a known risk factor, although the data show that opiate analgesics should be investigated.

Pancreatic cancer: any prospects for prevention?

Primary prevention of pancreatic cancer and public health measures to reduce its incidence are dependent on data from epidemiological studies. Currently, the only definite risk factor is smoking, although a diet rich in fruit and vegetables may be protective. The K-ras mutation may have a role in diagnosis and screening.

Production and evaluation of guidelines for the management of inflammatory bowel disease: the Leicester experience

Consensus guidelines for the management of patients with inflammatory bowel disease were produced by gastroenterologists, gastrointestinal surgeons and a cross-section of general practitioners (GPs) from Leicestershire in order to develop a seamless pattern of care with a common approach to diagnosis and treatment. It was hoped that the guidelines would encourage a movement towards care in the community for many patients with stable disease and so speed up new consultation rates. The study then assessed the impact of these guidelines on the referral letters of GPs to hospital consultants, the prediction of disease and adherence to them on re-referring patients after discharge. The guidelines were distributed to all 487 GPs in the Leicester Health Authority area and the gastroenterology teams within the hospitals. The value of the guidelines was assessed by an audit of referral letters, the length of time from referral letter to out-patient appointment, both before and after the launch of the guidelines, adherence to the guidelines on re-referral, and monitoring the outcome of the discharged patients. Whilst the guidelines may have helped GPs to manage stable patients in the community, the content of referral letters and the diagnostic abilities of GPs were not seen to improve since the launch of the guidelines. However, only 5% of stable patients who were discharged from one clinic were re-referred for inflammatory bowel disease.

Colorectal cancer prevention. An approach to increasing compliance in a faecal occult blood test screening programme

STUDY OBJECTIVE

The assessment of the uptake of colorectal cancer screening offered in a workplace setting.

DESIGN

Employees were offered a free faecal occult blood test (Haemoccult). A repeat letter was sent two months later to non-responders. Those with positive tests were invited for colonoscopy. Compliance was measured according to age, sex, and occupational group and the effects of reinviting non-compliers investigated.

SETTING

Leicester General Hospital, a large university teaching hospital.

PARTICIPANTS

990 employees aged 41 to 65 years.

MAIN RESULTS

Total compliance was 46% with women participating more than men (49% v 34%, chi 2 = 12.2, p < 0.001). The difference was mostly because of women aged 41 to 50 years complying more than their male counterparts (48% v 24%, chi 2 = 15.5, p < 0.0001). Participation was highest in clinical support staff (56%), nurses (52%), and clerical workers (46%). Uptake by doctors (26%) and managers (26%) was significantly lower than by clinical support staff and nurses (chi 2 > 5.5, p < 0.02). Remailing raised compliance slightly from 43.6% to 46.3%. Four employees (1%) had positive faecal occult blood tests but three were negative on repeat testing with dietary restrictions.

CONCLUSIONS

The government favours the development of health promotion programmes as stated in its document "Health at work in the NHS". The response in this study, showed methods to increase compliance must be developed if such programmes are to be successful. As uptake was similar to that in several community based programmes in general practice, workplace based programmes could offer a complementary method of delivering screening.

Flat adenomas exist in asymptomatic people: important implications for colorectal cancer screening programmes

BACKGROUND

Flat adenomas are non-exophytic with a flat top or central depression and histologically the depth of dysplastic tissue is never more than twice the mucosal thickness. Flat adenomas frequently contain severely dysplastic tissue, and may progress rapidly through the adenoma-carcinoma sequence. Flat lesions have never been described in a British asymptomatic population.

AIMS

To determine whether flat adenomas exist in an asymptomatic population participating in a large randomised controlled trial of flexible sigmoidoscopy screening.

PATIENTS

A total of 3000 subjects (aged 55-64 years) underwent screening by flexible sigmoidoscopy.

METHODS

All polyps were removed and sent for histology. The number of polyps with endoscopic and histological features of flat adenomas was recorded.

RESULTS

Three subjects had a total of four flat lesions--that is, one per 1000 people screened. Three contained severely dysplastic tissue, one a focus of adenocarcinoma. Three of the four lesions were less than 5 mm in size and the fourth was 15 mm in diameter.

CONCLUSIONS

Flat lesions with severe dysplasia exist in the asymptomatic population. This has major implications for gastroenterologists who should be trained to identify them. Their existence is of importance to molecular biologists and epidemiologists investigating the aetiology of colorectal cancer.

Ethanol tolerance and withdrawal responses in GABA(A) receptor alpha 6 subunit null allele mice and in inbred C57BL/6J and strain 129/SvJ mice

We have been using a genetic strategy to define the contribution of specific candidate genes, such as those encoding subunits of the gamma-aminobutyric acid type A receptor, to various ethanol sensitive responses. We have used the gene knockout approach in mouse embryonic stem cells to create mice in which the gene encoding the alpha6 subunit of the gamma-aminobutyric acid type A receptor is rendered nonfunctional. In the present report, we provide a detailed characterization of several behavioral responses to ethanol in these null allele mice. In a separate series of experiments, behavioral response to ethanol was compared between two inbred strains of mice that are commonly used as background stock in knockout experiments, namely C57BL/6J and Strain 129/SvJ. Wild type (alpha6+/+) and homozygous null allele (alpha6-/-) mice did not differ to the ataxic effects of ethanol on acute functional tolerance (95.8 +/- 8.7 vs. 98.8 +/- 5.7 mg/dl +/- SEM, respectively). Withdrawal hyperexcitability was assessed following chronic exposure to ethanol vapor (EtOH) or air (CONT) in inhalation chambers in a multiple withdrawal treatment paradigm. At the end of the last treatment cycle, mice were scored for handling induced convulsions (HIC). After adjusting for differences in blood ethanol concentration between genotypes at the end of the final treatment cycle, we observed a greater area under the 24-hr HIC curves in mice treated with ethanol (p < 0.0001) but did not detect an effect of genotype (alpha6+/+/CONT 3.1 +/- 2.0; alpha6-/-/CONT 5.5 +/- 2.5; alpha6+/+/EtOH 30.1 +/- 6.2; alpha6-/-/EtOH 33.0 +/- 5.8 mean units +/- SEM). We also examined these mice for differences in protracted tolerance; at approximately 26 hr into the final withdrawal cycle, each mouse was injected with ethanol (3.5 mg/g body weight) and sleep time was measured. We detected a significant effect of treatment (p < 0.001) with ethanol-treated mice demonstrating signs of tolerance as reflected by a reduction in duration of sleep time. However, effect of genotype was not significant (alpha6+/+/CONT 57.4 +/- 7.6; alpha6-/-/CONT 59.0 +/- 7.6; alpha6+/ +/EtOH 34.8 +/- 7.4; alpha6-/-/EtOH 30.8 +/- 5.6 min +/- SEM). From these data we conclude that the alpha6 subunit of the GABA(A)-R exerts little if any influence on acute functional tolerance, withdrawal hyperexcitability, or protracted tolerance. Strain 129/SvJ and C57BL/6J mice were also compared for acute functional tolerance and were found not to differ (96.3 +/- 4.4 vs. 94.8 +/- 11.3 mg/dl +/- SEM, respectively). Withdrawal hyperexcitability was assessed by comparing the area under the 24 hr HIC curves. Strain 129/SvJ mice displayed a much greater basal HIC response compared to C57BL/6J mice (19.8 +/- 4.3 vs. 0.2 +/- 0.2 mean units +/- SEM, respectively); after adjusting for differences in blood ethanol concentration between strains at the end of the final ethanol treatment cycle, the HIC response was markedly enhanced by ethanol treatment in Strain 129/SvJ mice but not in C57BL/6J mice (50.4 +/- 3.1 vs. 9.5 +/- 5.4 mean units +/- SEM, respectively). The effects of treatment (p < 0.0001), strain (p < 0.0001), and the interaction of strain with treatment (p < 0.01) were significant. Since many gene knockout mice are maintained on a mixed genetic background of Strain 129/SvJ and C57BL/6J, we conclude that significant differences in tests of withdrawal hyperexcitability may be confounded by the influence of genes that cosegregate with the gene targeted allele.