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Biomedical subjects

C B Williams

Publications and source records attributed to C B Williams.

At least 127 records · Page 7Linked to original sources
PubMed1990

Upper gastrointestinal pathology in familial adenomatous polyposis: results from a prospective study of 102 patients.

Multiple gastric and duodenal biopsy specimens from 102 asymptomatic patients with familial adenomatous polyposis, taken during a prospective endoscopic screening programme were examined. One hundred patients had microscopic gastroduodenal pathology, often in the absence of macroscopic lesions. Adenomas were found in 94 patients in the duodenum, in the second and third parts. Hyperplasia of villous and crypt epithelium was also seen, sometimes in the absence of adenomas: this may be a precursor of neoplastic change. In the stomach fundic gland polyps were the commonest abnormality, seen microscopically in 44 patients. Chronic antral gastritis was common in patients without fundic polyps. Gastric adenomas were present in six patients, all of whom also had duodenal adenomas. If duodenal adenomas in familial adenomatous polyposis have a similar malignant potential to those in the colorectum sequential endoscopy and biopsy are necessary to detect cancer in these patients.

Adenomatous Polyposis Coli↗
PubMed1989

Upper gastrointestinal cancer in patients with familial adenomatous polyposis.

102 patients with familial adenomatous polyposis underwent upper gastrointestinal endoscopy as a screening test for gastroduodenal adenomas. 100 had duodenal abnormalities (dysplasia in 94, and hyperplasia in 6), usually in the second and third parts of the duodenum (91%). The periampullary area was abnormal in 87 of 97 patients who had a biopsy specimen taken from this site (dysplasia 72, hyperplasia 13, and inflammation 2). By contrast, gastric dysplasia was found in only 6 patients. Classification of duodenal polyposis on a 5-grade scale (stages 0-IV), based on polyp number, size, histology, and severity of dysplasia, showed that 11 had stage IV disease: these patients are at greatest risk of malignant change and require close surveillance. The pattern of dysplasia observed in the upper gastrointestinal tract resembled the pattern of mucosal exposure to bile.

Adenoma↗
PubMed1989

T cell receptor beta-chain genes in the rat. Availability and pattern of utilization of V gene segments differs from that in the mouse.

We have constructed a specifically primed thymus cDNA library to study the V-region repertoire of the TCR beta-chain in the laboratory rat. From this library, we have isolated and sequenced 14 clones that hybridize with beta-chain constant region probes, eight of which contain V gene segments. Two of these eight contain a V gene segment whose sequence is 85% identical to mouse V beta 14, which has been estimated to be present in mouse thymocyte cDNA at a frequency of only 1.2%. Of the remaining six, four appear to be homologues of known mouse V beta sequences, and average 88% identity with their mouse counterparts. Two additional rat V regions have no homologue yet identified in the mouse, showing only 64 and 73% identity with the most closely related mouse sequences; at least one of these is present and polymorphic in the mouse genome, and may be located near one end of the V beta deletion known in the SWR strain. The availability and pattern of V beta gene segment expression in rat thymus appears, therefore, to differ significantly from the mouse. Two cDNA clones represent germline transcripts which show a J/C splice (one of which is defective) but no D/J rearrangement; two different J segments are used, indicating the presence of promoter activity 5' to these two J segments. In addition, by using V beta-specific probes derived from our cDNA clones, we have analyzed the distribution of V beta alleles among 10 inbred strains of rat. We find that rat V beta gene segments occur predominantly in single member subfamilies, and present evidence for the existence of three TCR V beta haplotypes defined by RFLP.

Amino Acid Sequence↗
PubMed1989

Refinements in determining the energy value of body tissue reserves and tissue gains from growth.

Energy density of weight gain increases with age and weight for age. Gains by more mature cattle contain more fat, less protein, and less water than gains by less mature cattle. The energy density of body tissue reserves mobilized during negative energy balance in early lactation is greater than that in the apparently contributing weight gains. The data reviewed had 140% as much fat and 60% as much protein in mobilized reserves as in gains. These observed differences justified the requantification of the energy density of tissue reserves mobilized for milk synthesis. The energy of gains was estimated by using equations published by the Agricultural Research Council to predict the fat and protein contents of the gains and multiplying them by their respective energy densities. The energy of mobilized reserves (weight losses) were estimated by predicting the fat and protein per kilogram of the contributing gains with the Agricultural Research Council equations, multiplying those fractions by 1.4 and .6, respectively, and multiplying the adjusted fractions by the respective energy densities of fat and protein. There was a close agreement between the predicted and observed energy values of both weight gains and weight losses.

Animals↗
PubMed1989

Application of neutral detergent fiber in modeling feed intake, lactation response, and body weight changes in dairy cattle.

A computer simulation model was developed using theoretical equations to predict DM intake in dairy cattle when the NDF and energy content of the diet and the energy requirements of the animal were known. An adjustment factor for NDF quality was determined to account for differences in intake with legume-based and grass-based diets when formulated at equal NDF content. Mathematical functions were developed from actual data to describe body reserve tissue mobilization and deposition and used to refine the determination of energy requirements and energy balance of the animal. Actual data on milk production and BW changes of Holstein cows under three feeding systems (individual concentrate, one- and two-group total mixed rations) were used to evaluate the model. There was good agreement between observed and predicted production responses, except for the one group total mixed ration, where daily milk yield was overpredicted during early lactation. Further calculations showed that the amount of available CP was too low to support the high milk production that the model predicted in early lactation with the one-group feeding system. This problem was corrected by incorporating a protein restriction on milk production using NRC guidelines.

Animal Feed↗
PubMed1988

Juvenile polyposis--a precancerous condition.

Clinical and pathological findings in 87 patients with juvenile polyposis have been reviewed; 1032 polyps were available from 80 of these patients; 840 were typical spherical juvenile polyps whereas 169 differed in being multilobulated or showing a villous configuration; 79 (46.7%) of the latter contained foci of epithelial dysplasia whereas only 76 (9.0%) of the typical juvenile polyps were dysplastic. The series also included 21 adenomas and two hyperplastic (metaplastic) polyps. The demonstration of dysplasia provides a histogenetic mechanism for the evolution of colorectal cancer from hamartomatous polyps; 18 juvenile polyposis patients have developed colorectal cancer at a mean age of 34 years (range 15-59). The clinical outcome was generally poor. No clinical or pathological distinction could be made between polyposis patients with and without colorectal cancer. Thus, the development of cancer in juvenile polyposis appears to be a random event. A working definition of juvenile polyposis is provided: (1) more than five juvenile polyps of the colorectum; and/or (2) juvenile polyps throughout the gastrointestinal tract; and/or (3) any number of juvenile polyps with a family history of juvenile polyposis. It is suggested that the condition should be treated as seriously as familial adenomatous polyposis except that regular colonoscopic surveillance may obviate the need for prophylactic colectomy.

Adenomatous Polyposis Coli↗
PubMed1988

Brush cytology of the colon and rectum in ulcerative colitis: an aid to cancer diagnosis.

In a prospective study of 100 patients with ulcerative colitis, 82 of whom had extensive colitis, carcinoma and dysplasia were distinguished cytologically from reactive hyperplasia. Six patients had carcinoma complicating colitis and satisfactory samples were obtained from five; the cytological appearances were interpreted as carcinoma in three and as dysplasia in two. Seventy eight patients had not developed carcinoma or dysplasia; the cytological appearances were interpreted as negative for dysplasia in 75 and indefinite for dysplasia in three. In patients who had developed dysplasia the changes seemed to be more widespread on cytological rather than on histological examination. Brush cytology may complement histological assessment in patients with ulcerative colitis who have developed strictures or in whom there is a high suspicion of neoplastic change.

Adenoma↗
PubMed1987

Angiodysplasia--an uncommon cause of colonic bleeding: colonoscopic evaluation of 1,050 patients with rectal bleeding and anaemia.

Angiodysplasia of the colon was diagnosed in 31 out of 1,050 patients (3%) presenting with rectal bleeding or anaemia, among 10,000 colonoscoped at St. Mark's Hospital. The lesions were identified in 16 out of 879 (2%) patients with rectal bleeding, in 15 out of 171 (9%) patients with anaemia, and in a further three patients without features of blood loss. The angiodysplasia lesions were predominantly in the right colon (76%) and occurred with a similar frequency (12%) in the transverse and the left colon. Affected patients (59% male and 41% female) were in the older age group (53-89 years; mean age 69.5 years) but only one patient had known aortic valve disease. Angiodysplasia is an important diagnosis to consider in patients presenting with colonic bleeding or anaemia because it can be treated in the majority of cases by endoscopic electrocoagulation. However in our experience it is less common (3%) than previously suggested by other authors (40-67%). Endoscopic over-diagnosis is possible when intramucosal capillaries with no bleeding tendency on local traumatisation or biopsy are included in the diagnosis but these lesions are not true angiodysplasia.

Aged↗
PubMed1987

Selective biopsy of human Peyer's patches during ileal endoscopy.

During routine lower gastrointestinal endoscopy of children for suspected chronic inflammatory bowel disease, it is possible to visualize lymphoid follicles (Peyer's patches) in the last few centimeters of the terminal ileum. Biopsy specimens have been taken from these Peyer's patches and the lymphoid cells have been isolated by collagenase digestion. The mean cell yield of Peyer's patch cells was 1.7 x 10(8) lymphocytes/g tissue. Isolated Peyer's patch cells were 26%-54% CD3+ (pan T cells), 14%-34% CD4+ (helper/inducer T cells), and 9%-17% CD8+ (suppressor/cytotoxic T cells). Twenty six percent to 48% of the Peyer's patch cells were B cells; less than 1% contained cytoplasmic immunoglobulin A. When stimulated in vitro with phytohemagglutinin or pokeweed mitogen, cells from Peyer's patches proliferated. The successful isolation of functional cells from Peyer's patches will now allow studies to be done at the afferent limb of mucosal immunoregulation in humans.

Adolescent↗
PubMed1987

Survival analysis of adverse effects data in the Beta-Blocker Heart Attack Trial.

Monitoring for adverse effects in an integral part of controlled clinical trials. Traditionally the results of monitoring are reported as either cumulative percentages at the end of the study or cross-sectional percentages at a given time in the study. These results are likely to underestimate the true number of complaints because participants may be withdrawn (e.g., deaths, losses to follow-up, and refusals) before they ever complain of an adverse effect. However, survival analysis methods can be used to compare the distributions of "time to first complaint" in the active and placebo treatment groups, taking into account withdrawals. Participants in the Beta-Blocker Heart Attack Trial were monitored for possible adverse effects. On each follow-up visit they were asked whether they had had any of four conditions (blacking out, fatigue, depression, and bronchospasm) since their previous visit about 3 months earlier. The patients were followed for up to 30 months. For fatigue and bronchospasm, the complaint-free time was significantly longer in the placebo vs. active (propranolol) treatment group (P less than 0.005).

Adult↗
PubMed1987

Practical aspects of endoscopic management of malignant polyps.

World experience now overwhelmingly supports the policy of conservative management by endoscopic snare polypectomy of "focal" cancer in polyps (malignancy in adenomas and polypoid carcinomas), providing that the polyp is pedunculated and that endoscopic and histological criteria are favorable. Invasion to within 2-3 mm of the snare-resection line is acceptable, providing that the advancing tumour margin is well-circumscribed. Unfavourable characteristics include poorly differential tumour, involvement of stalk vessels, and sessile configuration. This management policy applied to 90 patients between 1971 and 1981 resulted in successful 5-year follow-up of the 74 patients treated by polypectomy alone. Among the 16 patients managed surgically, no local lymph nodes were involved in any case, although 4 patients were found to have residual local tumour at the polypectomy site.

Biopsy↗
PubMed1986

Who's for CO2?

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Barium Sulfate↗
PubMed1986

Colonoscopy.

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Colonic Diseases↗
PubMed1986

Histological abnormalities in biopsies from macroscopically normal colonoscopies.

One hundred and nineteen children with gastrointestinal symptoms underwent colonoscopy during the course of one year. Out of 39 children that were reported as yielding normal results on endoscopic examination, six had disease detectable only by histology. The pathology included cases of microscopic colitis, Crohn's disease, and indeterminate colitis. To exclude large bowel inflammation as a cause of gastrointestinal symptoms biopsy specimens should always be taken at endoscopy.

Adolescent↗