Search PubMed⌕ Search

Biomedical subjects

C B Williams

Publications and source records attributed to C B Williams.

At least 73 records · Page 4Linked to original sources
PubMed1995

Faecal occult blood testing and colonoscopy in the surveillance of subjects at high risk of colorectal neoplasia.

Colonoscopy is the established method of surveillance of subjects at high risk of developing colorectal neoplasia but the procedure is expensive, time consuming and occasionally hazardous. Faecal occult blood tests can be prepared at home and are cheap, simple and safe. Hemeselect is an immunological faecal occult blood test that is more sensitive for colorectal cancer than Haemoccult. The aim of this study was to determine the sensitivity of the Hemeselect test for asymptomatic colorectal neoplasia in subjects at high risk of the disease who were undergoing colonoscopy, thus assessing its suitability as an alternative means of screening high-risk groups. A total of 919 asymptomatic subjects were asked to complete Hemeselect tests. These were completed satisfactorily by 808 individuals (compliance rate 88 per cent) and were positive in 164 patients (20 per cent). At colonoscopy 11 cancers were detected in ten patients (seven Hemeselect positive) and 36 (16 Hemeselect positive) had at least one adenoma 1 cm or more in diameter. The test sensitivites of Hemeselect for carcinoma and large (1 cm or more) adenomas were 70 and 44 per cent respectively. In a subset of 417 subjects who also completed Haemoccult tests, the sensitivities were 33 and 18 per cent. Hemeselect specificity is 88 per cent compared with 98 per cent for Haemoccult. While the sensitivity of Hemeselect is higher than that of Haemoccult, it is still insufficient to replace colonoscopy in high-risk groups.

Colonoscopy↗
PubMed1995

Intraoperative measurement of colonic anatomy and attachments with relevance to colonoscopy.

This study examined the variations in colonic length and mesenteric attachments in 118 patients undergoing laparotomy. Measurements were taken according to a set protocol with the bowel pulled medially, or towards the pubic symphysis or the xiphisternum, mimicking the possible displacements that may occur during colonoscopy. A free sigmoid loop was not present in 20 patients (17 percent) because of adhesions. A descending mesocolon of 10 cm or more in length was recorded in ten patients (8 percent) and an ascending mesocolon 10 cm or greater in 11 (9 percent). Some 24 patients (20 percent) had mobile splenic flexures and in 34 (29 percent) the mid-transverse colon reached the symphysis pubis or lower when pulled downwards. Mean (range) total colonic length was 114.1 (68-159) cm. This study helps define anatomical variations that may affect the facility, or otherwise, of colonoscopy.

Adult↗
PubMed1995

A peroperative comparison of Western and Oriental colonic anatomy and mesenteric attachments.

It has been suggested that the Oriental colon is easier to colonoscope than its Western counterpart. The aim of this study was to investigate possible differences in colonic anatomy between Western and Oriental patients that might explain this observation. Measurements of colonic length and mesenteric attachments were taken according to a set protocol from 115 Western (Caucasian) and 114 Oriental patients at laparotomy. Sigmoid adhesions were found more frequently in Western (17%) compared to Oriental (8%) patients, P = 0.047. A descending mesocolon of > or = 10 cm occurred in 10 (8%) Western patients but only 1 (0.9%) Oriental patient, P = 0.01. The splenic flexure was more frequently mobile in Western patients (20%) compared to Oriental (9%) patients, P = 0.016. In 29% - of Western patients the mid-transverse colon reached the symphysis pubis, or lower when pulled downwards in contrast to 10% of Oriental patients, P < 0.001. There was no significant difference in total colonic length comparing Western (median = 114 cm, range 68-159 cm) to Oriental (median = 111 cm, range 78-161 cm) patients. Western patients have a higher incidence of sigmoid colon adhesions and increased colonic mobility when compared to Orientals. These findings support the observation that colonoscopy is a more difficult procedure in Western patients.

Adult↗
PubMed1995

Can barium enema indicate when colonoscopy will be difficult?

The barium enemas of 48 consecutive patients, who were technically difficult to intubate at colonoscopy, were compared to those of 46 patients who were not. Measurements were taken of colonic length and mobility, and an assessment made of diverticular disease. Rectosigmoid length (mean difficult group = 61 cm, mean control = 54 cm, P = 0.01) and total colonic length (mean difficult group = 157 cm, mean control = 140 cm, P < 0.0001) were greater in the difficult colonoscopy group as were transverse colon mobility (mean difficult group = 10 cm, mean control = 7 cm, P = 0.003) or redundancy (transverse colon reaching the true pelvis on the erect film); 65% difficult group vs 17% control group, P < 0.0001. The presence of moderate or severe diverticular disease was also greater in the difficult (23%) compared to the control (4%) group, P = 0.02. When available, assessment of a previous barium enema is a useful guide to probable technical difficulty of colonscopy. It may allow appropriate allocation of potentially difficult cases to specialist endoscopy lists.

Adolescent↗
PubMed1995

Intravenous antispasmodic and patient-controlled analgesia are of benefit for screening flexible sigmoidoscopy.

The possible benefits of premedication with the antispasmodic hyoscine n-butyl bromide (hyoscine) and analgesia with inhaled nitrous oxide/oxygen mixture (nitrous oxide) were assessed in a double-blinded, placebo-controlled trial. Consecutive patients at normal risk for cancer undergoing screening flexible sigmoidoscopy were randomly allocated to receive either (1) intravenous hyoscine 20 mg plus inhaled oxygen on demand (n = 40), (2) sterile water injection plus inhaled nitrous oxide on demand (n = 48), or (3) sterile water injection plus inhaled oxygen on demand (n = 43). One recently trained primary care physician performed all procedures. Duration of the procedure, endoscopic findings, and depth of insertion were recorded. After the examination, screenees rated their degree of pain during the procedure using a visual analogue scale. Depth of insertion did not differ between the three study groups, but the duration of the procedure was significantly less in the hyoscine group (median, 12.5 minutes) as compared with placebo (median, 18 minutes; p = .0008). Fifty-four percent of screenees chose to use the on-demand gas. Pain scores were significantly lower in those individuals who inhaled nitrous oxide as compared with placebo (p = .045). Premedication with antispasmodic shortens total procedure time for flexible sigmoidoscopy by a moderately experienced endoscopist as compared with placebo. In this study, a significant number of screenees experienced discomfort during flexible sigmoidoscopy, which appeared to be reduced by offering nitrous oxide inhalation.

Administration, Inhalation↗
PubMed1995

The effect of treatment on lymphokine-secreting cells in the intestinal mucosa of children with Crohn's disease.

BACKGROUND: Recent studies have shown both interleukin 2 (IL-2) and interferon gamma (IFN) to be elevated in patients with active Crohn's disease compared to ulcerative colitis or non-inflammatory bowel disease controls. However the effect of treatment on these lymphokines has not been studied. PATIENTS AND METHODS: Using a reverse haemolytic plaque assay the percentage of lymphokine-secreting cells was determined in the intestinal mucosa of children with Crohn's disease before and after 8 weeks of treatment with either enteral nutrition, cyclosporin or steroids. RESULTS: Before treatment, a high percentage of cells isolated from mucosal biopsies secreted IL-2 or interferon-gamma. Eight weeks' treatment with the immunosuppressive agents cyclosporin, or with corticosteroids, produced a significant reduction in the percentage of IL-2 secreting cells, although only for the former was there also a reduction in interferon-gamma secreting cells. Enteral nutrition however, produced a reduction in lymphokine-secreting cells equivalent to cyclosporin and produced the best histological and clinical improvement. CONCLUSION: Enteral nutrition and cyclosporin can down-regulate lymphokine secretion in the gut in Crohn's disease.

Adolescent↗
PubMed1995

The role of small bowel radiology in the diagnosis and management of Crohn's disease.

A total of 50 children with Crohn's disease were examined by barium follow-through and colonoscopy with ileoscopy, to determine the value of small bowel radiology. Of these children, 40 (80%) had evidence of small bowel Crohn's disease on ileoscopy and/or barium follow-through. Twenty-two (44%) had disease confined to the terminal ileum. Radiology diagnosed disease proximal to the terminal ileum in 18 cases (36%), including 5 children in whom the terminal ileum was normal. Ileoscopy was not possible in nine patients (18%), six of whom had small bowel disease on barium follow-through. Colonic involvement, demonstrated in 34 (68%), was the sole site of disease in 6 (12%). Fifteen (30%) children had surgery, which in six (12%) was determined by the radiological findings of complicated small bowel disease. As the terminal ileum may be uninvolved in the presence of proximal ileal disease, normal ileoscopy does not exclude small bowel Crohn's disease. Small bowel radiology remains necessary to assess the full extent of Crohn's disease in children.

Adolescent↗
PubMed1995

Variables associated with the risk of colorectal adenomas in asymptomatic patients with a family history of colorectal cancer.

The results of screening individuals referred to the Family Cancer Clinic at St Mark's Hospital from 1986 are presented. Colonoscopy was performed in 644 asymptomatic individuals (from 436 families) with a family history of colorectal cancer. Sixty nine (15.8%) of the families fulfilled the Amsterdam criteria for the hereditary non-polyposis colorectal cancer syndromes (HNPCC). Seven cases of colorectal cancer were diagnosed at an average age of 49 years; six at Dukes's stage A and one at stage C, four in subjects from Amsterdam criteria families. One hundred and forty four (22.4%) subjects had one or more adenomas. The prevalence of adenomas in the subjects from Amsterdam criteria families was 34 of 127 (26.8%) compared with 110 of 517 (21.3%) in those from other families; the age and sex adjusted odds ratio (OR) was 1.76 (p = 0.02). Factors influencing the prevalence of adenomas in screened individuals were evaluated. Multivariate analysis showed that independent variables significantly related to the risk of adenomas were: age (p < 0.0001), sex (p = 0.0002), and the number of generations (> or = 2 v 1) of relatives affected by either colorectal cancer or adenomas (p = 0.0006). The latter variable was more highly predictive of the probability of finding an adenoma at colonoscopy than a family history of two generations with cancer only (p = 0.056). The OR of having colorectal adenomas increased with age, by about twofold for each decade, and was twice as high in men than women, and in subjects with two or more generations relative to those with one generation affected by colorectal cancer or adenomas. Six of seven patients with cancer and 46 of 144 (31.9%) with adenomas had lesions proximal to the splenic flexure only. The proportion of individuals with proximal adenomas only was 47.1% in Amsterdam criteria families and 27.3% in the others (p=0.03). These findings support the view that colonoscopy rather than sigmoidoscopy is the method of choice for screening high risk groups.

Adenoma↗
PubMed1995

First clinical results with a real time, electronic imager as an aid to colonoscopy.

The early clinical results are described of a real time, electromagnetic imaging system as an aid to colonoscopy. After gaining experience with the use of the system, one experienced endoscopist was randomised to perform consecutive colonoscopies either with (n = 29) or without (n = 26) the imager view. All procedures were recorded on computer disk and replayed for retrospective analysis. Total colonoscopy was achieved in all patients except one (imager view not available). Comparing intubation time and duration of loop formation per patient, there was no significant difference between the two study groups. The number of attempts taken to straighten the colonoscope pre patient, however, was less when the endoscopist was able to see the imager view, p = 0.03. Hand pressure was also more effective when the endoscopist and endoscopy assistant could see the imager display, p = 0.02. Preliminary experience suggests that real time, electronic imaging of colonoscopy is safe, effective, and will improve the accuracy of the procedure.

Abdomen↗
PubMed1995

The quest for a more acceptable bowel preparation: comparison of a polyethylene glycol/electrolyte solution and a mannitol/Picolax mixture for colonoscopy.

Eighty-nine consecutive patients attending for day-case colonoscopy were randomly allocated either polyethylene glycol/balanced electrolyte (PEG) mixture (n = 45) or a mannitol/Picolax mixture (n = 44). Both preparations were administered in two fractions. Patients recorded their experience of the preparation on a questionnaire and one of two experienced endoscopists (unaware of the type of preparation given) assessed the result of bowel cleansing. Carbon dioxide insufflation was used for all examinations. Good/excellent bowel cleansing occurred in significantly more patients given PEG, 43 (96%), than those allocated mannitol/Picolax, 34 (77%), p = 0.01. More patients receiving mannitol/Picolax were able to complete the preparation in full than patients receiving PEG (38 vs 27, p = 0.01). More patients found the taste of mannitol/Picolax pleasant compared to PEG (46% vs 20%). Both preparations had a similar side-effect profile. Of those patients tested, 13% receiving mannitol/Picolax had a postural drop in blood pressure and blood parameters suggestive of mild dehydration. A fractionated administration of PEG as a bowel preparation for day-case colonoscopy is well tolerated and superior as a cleansing agent to a mannitol/Picolax combination. Provided carbon dioxide is used as the insufflating agent, mannitol/Picolax is an acceptable alternative in fit, young patients intolerant of PEG.

Administration, Oral↗
PubMed1995

Application of a computer model to predict optimum slaughter end points for different biological types of feeder cattle.

A bioeconomic model was developed to predict slaughter end points of different genotypes of feeder cattle, where profit/rotation and profit/day were maximized. Growth, feed intake, and carcass weight and composition were simulated for 17 biological types of steers. Distribution of carcass weight and proportion in four USDA quality and five USDA yield grades were obtained from predicted carcass weights and composition. Average carcass value for each genotype was calculated from these distributions under four carcass pricing systems that varied from value determined on quality grade alone to value determined on yield grade alone. Under profitable market conditions, rotation length was shorter and carcass weights lighter when the producer's goal was maximum profit/day, compared with maximum profit/rotation. A carcass value system based on yield grade alone resulted in greater profit/rotation and in lighter and leaner carcasses than a system based on quality grade alone. High correlations ( > .97) were obtained between breed profits obtained with different sets of input/output prices and carcass price discount weight ranges. This suggests that breed rankings on the basis of breed profits may not be sensitive to changes in input/output market prices. Steers that were on a grower-stocker system had leaner carcasses, heavier optimum carcass weight, greater profits, and less variation in optimum carcass weights between genotypes than steers that were started on a high-energy finishing diet at weaning. Overall results suggest that breed choices may change with different carcass grading and value systems and postweaning production systems. This model has potential to provide decision support in marketing fed cattle.

Abattoirs↗
PubMed1995

Simulated influence of postweaning production system on performance of different biological types of cattle: I. Estimation of model parameters.

Breed parameters for a computer model that simulated differences in the composition of empty-body gain of beef cattle, resulting from differences in postweaning level of nutrition that are not associated with empty BW, were estimated for 17 biological types of cattle (steers from F1 crosses of 16 sire breeds [Hereford, Angus, Jersey, South Devon, Limousin, Simmental, Charolais, Red Poll, Brown Swiss, Gelbvieh, Maine Anjou, Chianina, Brahman, Sahiwal, Pinzgauer, and Tarentaise] mated to Hereford and Angus dams). One value for the maximum fractional growth rate of fat-free matter (KMAX) was estimated and used across all breed types. Mature fat-free matter (FFMmat) was estimated from data on mature cows for each of the 17 breed types. Breed type values for a fattening parameter (THETA) were estimated from growth and composition data at slaughter on steers of the 17 breed types, using the previously estimated constant KMAX and breed values for FFMmat. For each breed type, THETA values were unique for given values of KMAX, FFMmat, and composition at slaughter. The results showed that THETA was most sensitive to KMAX and had similar sensitivity to FFMmat and composition at slaughter. Values for THETA were most sensitive for breed types with large THETA values (Chianina, Charolais, and Limousin crossbred steers) and least sensitive for breed types with small THETA values (purebred Angus, crossbred Jersey, and Red Poll steers).(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1995

Simulated influence of postweaning production system on performance of different biological types of cattle: II. Carcass composition, retail product, and quality.

A computer simulation model was used to characterize the response in carcass composition, retail product, and quality of steers from F1 crosses of 16 sire breeds (Hereford, Angus, Jersey, South Devon, Limousin, Simmental, Charolais, Red Poll, Brown Swiss, Gelbvieh, Maine Anjou, Chianina, Brahman, Sahiwal, Pinzgauer, and Tarentaise) mated to Hereford and Angus dams, grown under nine backgrounding systems, and finished at either a low (1.0 kg) or high (1.36 kg) ADG. The backgrounding systems were a high ADG (.9 kg) for 111, 167, or 222 d, a medium ADG (.5 kg) for 200, 300, or 400 d, a low ADG (.25 kg) for 300 or 400 d and 0 d backgrounding. For specific genotype x production system combinations, results showed that carcasses of compensating steers may be either leaner, not different in fatness, or fatter than carcasses of steers put on a finishing diet directly after weaning. Systems in which steers gained a greater proportion of the final slaughter weight over long durations of growth restriction resulted in leaner carcasses. There were 12 common production systems in which 13 of the genotypes produced a carcass with a maximum of 28% fat or with a marbling score of 11 or greater. These results suggest sire breeds used to produce these steers can be used over a wide range of nutritional and management environments, and that a mixed group of steers can be fed and managed similarly from weaning to slaughter to produce a carcass with a specified composition, retail product, or quality.

Aging↗
PubMed1995

Simulated influence of postweaning production system on performance of different biological types of cattle: III. Biological efficiency.

Methods were developed and incorporated into a previously published computer model to predict ME intake and calculate biological efficiencies in terms of grams of empty BW (EBW) and fat-free matter (FFM) gained/megacalorie of ME consumed from weaning to slaughter. Efficiencies were calculated for steers from F1 crosses of 16 sire breeds (Hereford, Angus, Jersey, South Devon, Limousin, Simmental, Charolais, Red Poll, Brown Swiss, Gelbvieh, Maine Anjou, Chianina, Brahman, Sahiwal, Pinzgauer, and Tarentaise) mated to Hereford and Angus dams, grown under nine backgrounding systems, finished at either a low (1.0 kg) or high (1.36 kg) ADG, and slaughtered at 300 kg carcass weight, small or greater degree of marbling, and 28% carcass fat. Backgrounding systems were high ADG (.9 kg) for 111, 167, or 222 d, medium ADG (.5 kg) for 200, 300, or 400 d, and low ADG (.25 kg) for 300 or 400 d, and 0 d backgrounding. The high ADG finishing system was more biologically efficient than the low ADG finishing system, and generally backgrounding systems were less biologically efficient than direct finishing after weaning (0 d backgrounding). Large-framed breeds were more efficient at the constant carcass weight and carcass fatness end point, and breeds that achieved the marbling end point at low levels of carcass fatness were more efficient at this end point. Some small-framed breeds gained EBW more efficiently but gained FFM less efficiently than some of the large-framed breeds. Variation in efficiency between genotypes was greatest with 0 d backgrounding and decreased in the other backgrounding systems.

Aging↗
PubMed1995

Silage or limit-fed grain growing diets for steers: I. Growth and carcass quality.

The influence of energy source (silage- [S] or grain- [G] based) on organ growth, carcass quality, and meat acceptability independent of rate of gain was examined. Sixty-four Angus steers were allotted to one of the two treatments and given ad libitum access to silage or limit-fed grain for 145 d. All steers were then given ad libitum access to a grain diet for 45, 75, or 105 d. Eight steers from each treatment were slaughtered at the end of the growing phase and at each of the termination dates. The silage-based growing diet consisted (DM basis) of 55% sorghum silage (averaged 23.6% dry matter), 22% alfalfa hay, 10.8% ground shelled corn, and 10.8% soybean meal and contained 12.8% CP. Dry matter in the grain-based diet, composed of 76.5% ground shelled corn, 5% soybean meal, 13.6% cottonseed hulls, 3.5% molasses, and .4% salt and 1% limestone, contained 12.1% CP. It was limit-fed to produce rates of gain similar to the silage diet eaten ad libitum, using net energy for gain of each diet calculated from organic matter digestibility determined in digestion trials. The finishing diet was similar to the grain growing diet except that alfalfa hay replaced the cottonseed hulls. No implants or ionophores were used. High silage moisture decreased ADG the first 45 d, so steers fed grain gained faster, but thereafter gains were similar. At the end of the growing phase, steers fed grain had heavier shrunk and empty body weights and larger livers. However, liver size was not different when adjusted for growing ADG. By 45 d with ad libitum access to the finishing diet, 75% of the carcasses from steers fed both diets graded Choice. Steers fed silage had tougher (P < .05) steaks with less flavor intensity (P < .05) at the end of the growing phase; these differences diminished after 75 d on feed. These results suggest that choice beef can be produced in only 45 d in the feedlot, but tenderness and flavor among Choice carcasses remained inferior for steers fed silage for at least 75 d on a high-grain diet.

Animals↗
PubMed1994

Non-polypoid adenoma of the large intestine.

In order to find non-polypoid (flat) adenomas in the large intestine, one hundred and twenty-six consecutively resected large bowels were stained with methylene blue or haematoxylin and examined using a stereoscopic microscope with special attention to pit pattern abnormalities. The primary diseases were classified into familial adenomatous polyposis (FAP) in 9 cases, multiple adenomas in 2 cases, colorectal cancers in 90 cases, Crohn's disease in 5 cases, ulcerative colitis in 2 cases, constipation in 9 cases, diverticular disease in 3 cases and others in 6 cases, respectively. Thirty-five flat adenomas were detected in 14 colons (14/126 = 11%). Twenty-one flat adenomas were found in 9 non-FAP cases (7 colons removed for cancer and 2 for multiple adenomas) and the remaining 14 flat adenomas were found in 5 FAP colons. No flat adenomas were found in any of the 25 colons removed for non-neoplastic disease. Nine flat adenomas (26%) had a depressed shape. The mean age of the non-FAP cases was 57 years and that of the FAP cases was 29 years (P < 0.005). The mean size of non-FAP flat adenomas was 6.1 mm and that of FAP flat adenomas was 3.1 mm (P < 0.005). Non-FAP flat adenomas were more frequently right-sided than those in FAP. Epithelial dysplasia was graded as mild in 31 (89%) and moderate in 4 (11%), respectively. Moderate dysplasia was found in non-FAP cases exclusively. These results suggest that flat adenomas may be heterogeneous. The significance of these lesions is discussed.

Adenoma↗