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C B Williams

Publications and source records attributed to C B Williams.

At least 109 records · Page 6Linked to original sources
PubMed1992

A computer model to predict the effects of level of nutrition on composition of empty body gain in beef cattle: II. Evaluation of the model.

A computer model developed to predict composition of empty body gain of beef cattle fed at different levels of nutrition was evaluated with data from one unpublished and seven published experiments. These experiments used several breeds of beef cattle growing at rates that varied from negative to fast and various combinations of these growth rates. There was close agreement between observed and simulated absolute treatment means for fatness, except when animals were fed diets low in protein. In this case, experimental animals fed inadequate protein grew at slower rates and became fatter than contemporaries fed adequate protein, whereas the model predicted the opposite. Ability of the model to predict effects of nutrition not associated with changes in BW was evaluated using the proportion of residual variation in experimental fat percentage accounted for by the model, after fitting linear and quadratic terms for empty BW. The model accounted for 13.8 to 56.2% of the residual variation in observed fatness in four experiments in which significant differences in fatness were observed among nutritional treatments after accounting for differences in empty BW. Regression of observed fatness on model-simulated fatness resulted in regression coefficients that were positive and close to 1 in these four experiments. This suggests that the model can accurately predict some of the effects of nutrition on fatness that are not associated with changes in empty BW.

Adipose Tissue↗
PubMed1991

Organization and nucleotide sequence of the rat T cell receptor beta-chain complex.

We have characterized four overlapping genomic clones containing the DA rat TCR C beta complex, which span a total of 23 kb and bear two closely related complexes of gene segments. The D beta 1-J beta 1-C beta 1 and the D beta 2-J beta 2-C beta 2 complexes each contain a single diversity segment, six joining segments and four exons that encode the C region. All gene segments appear to be functional except J beta 2.5, which has a 5-bp frame-shifting deletion. This organizational pattern is identical to that of the mouse, and the homologous rat and mouse coding regions share about 92% nucleotide sequence identity. Our sequence comparisons indicate that a localized gene correction event has homogenized the sequences of the first exons of C beta 1 and C beta 2 in the evolutionary time since rats and mice became separate species. We have identified three repetitive elements, each flanked by short direct repeats, present in the region "brain-specific" identifier (ID) sequences, another is a truncated member of the LINE I class of repetitive elements, and the third is a member of the Alu type 2 family. The insertion of at least two, and probably all, of these elements has occurred since the time of rat/mouse divergence. We have identified a substantial number of "cryptic" rearrangement signals (heptamer/nonamer) in the C beta locus, which match the consensus sequence as well or better than authentic signals, and may represent sites of nonfunctional rearrangements.

Animals↗
PubMed1991

Retention of nondeflating balloon in small bowel. Case report and review of the literature.

Intubation of the upper gastrointestinal tract with balloon catheters has a role in the diagnosis, treatment, and research of many gastrointestinal conditions. A potential complication of this procedure, albeit rare, is failure of the balloon to deflate, thereby preventing removal of the intestinal tube. We describe a case where this problem arose and the series of maneuvers that were attempted to resolve it. Attempts at overdistending the balloon, reaching it via endoscopy, and ultrasound localization of the balloon all failed. The tube was successfully removed following CT-guided percutaneous needle puncture of the impacted balloon. The published experience with nondeflating catheter balloons in hollow viscera has been reviewed and the suggested methods for deflation or puncture are discussed.

Adult↗
PubMed1991

Malignant colorectal polyps: venous invasion and successful treatment by endoscopic polypectomy.

We reviewed the pathology of 81 malignant colorectal polyps in 80 patients treated by endoscopic polypectomy and assessed the importance of carcinomatous invasion of veins in the stalk (submucosa). All the patients were followed up for at least five years. Venous invasion was present in 30 of the polyps (37%). The histological features of lymphatic invasion were considered too subjective to be of value. Most of the tumours were well or moderately differentiated adenocarcinomas, one was poorly differentiated, and one was a signet ring cell carcinoma. Seventy one patients were treated by polypectomy alone, and 58 of these were alive and well five years later, with no evidence of recurrence. Nine died of unrelated causes within five years, but four died of carcinomatosis: one with recurrent tumour, one with a possible metachronous caecal cancer, and in two patients there was late development of malignancy of uncertain nature. The remaining nine patients underwent surgical resection after initial endoscopic polypectomy because of incompleteness of excision, poor differentiation of the tumour, or a decision by the surgeon. Tumour was not present in the resection specimens apart from a single lymph node deposit in the patient with signet ring cell carcinoma. These nine patients were alive and well without evidence of recurrence five years later. The results reemphasize the necessity of good cooperation between endoscopist and pathologist, meticulous laboratory technique, strict histopathological criteria including examination of resection margins and degree of differentiation of the tumour, and regular endoscopic follow up. Endoscopic polypectomy of pedunculated and sessile malignant polyps is adequate treatment if the lesion can be removed in one piece, the tumour is well or moderately differentiated, and local excision is judged complete by endoscopic and histological criteria. Patients with histologically incompletely excised polyps, containing well or moderately differentiated carcinoma, can be safely managed by conservative treatment provided the endoscopist is certain there is no residual tumour. Venous invasion by tumour is a common finding in malignant colorectal polyps and seems to have no prognostic importance.

Adult↗
PubMed1991

Primary B-cell immunoblastic lymphoma of pancreas.

Extranodal lymphoma may present as an abdominal mass without evidence of disease elsewhere. Predominant pancreatic involvement with lymphoma is rare. Presenting as a pancreatic mass, it may be difficult to differentiate if from carcinoma. Ultrasound-guided fine needle biopsy and immunocytochemistry are helpful in establishing a histological diagnosis. It is important to differentiate lymphoma from carcinoma, because lymphoma is treated differently and has a better prognosis.

Adult↗
PubMed1990

A family of three mouse potassium channel genes with intronless coding regions.

To understand the molecular mechanisms responsible for generating physiologically diverse potassium channels in mammalian cells, mouse genomic clones have been isolated with a potassium channel complementary DNA, MBK1, that is homologous to the Drosophila potassium channel gene, Shaker. A family of three closely related potassium channel genes (MK1, MK2, and MK3) that are encoded at distinct genomic loci has been isolated. Sequence analysis reveals that the coding region of each of these three genes exists as a single uninterrupted exon in the mouse genome. This organization precludes the generation of multiple forms of the protein by alternative RNA splicing, a mechanism known to characterize the Drosophila potassium channel genes Shaker and Shab. Thus, mammals may use a different strategy for generating diverse K+ channels by encoding related genes at multiple distinct genomic loci, each of which produces only a single protein.

Amino Acid Sequence↗
PubMed1990

Is there a preference for different ways of performing faecal occult blood tests?

Low compliance with faecal occult blood screening reduces the power of clinical trials, potential benefit, and efficiency. It has been proposed that the faecal manipulation required to perform conventional guaiac based tests may be an important factor in low compliance. The aim of this study was to evaluate whether use of a new method (vehicle) of stool collection for the faecal occult blood guaiac test would be preferred to the established standard. A novel self-interpreted test, Early Detector (ED), requires the subject to apply a guaiac/peroxide spray to a stool sample collected simply by wiping the anus with a specimen pad. To determine whether this method would be preferred to the stool manipulation required by Haemoccult (HO) and to compare test validity, employees at a London company were invited to use both tests. Eight-hundred and fifty-seven subjects were shown both tests. Before use, 48% indicated a preference for the method of Early Detector; 24% chose Haemoccult (p less than 0.001), while 28% indicated no immediate preference. Seven-hundred and one performed both tests. After use, 74% preferred ED; 5% preferred HO (p less than 0.001); 21% had no preference (NP). The preference for the ED test method was consistent by sex categories, age groups and occupational class. Logistics, aesthetics, and immediacy of results were the main reasons indicated for choosing ED. Whether the preference for ED could result in higher compliance remains to be proven. Its high positivity (14%), however, would preclude its use as a sole test to determine the need for endoscopic and/or radiologic investigation in the screened patient.

Adult↗
PubMed1990

Barium studies and ileoscopy compared in children with suspected Crohn's disease.

The findings on barium follow through, ileoscopy and biopsy of the terminal ileum in 46 children with suspected chronic inflammatory bowel disease have been compared to the final clinical diagnosis. Ileoscopy and barium follow through agreed in 91%, barium follow through and biopsy in 80% and barium follow through, ileoscopy and biopsy in 76% of cases. A pronounced lymphoid hyperplasia pattern was present radiologically in 24%, and was a source of error in two cases. Barium follow through compared favourably to ileoscopy or biopsy individually, detecting 18 of 20 and 17 of 20 cases respectively; however, ileoscopy combined with biopsy diagnosed every case. The sensitivity of the barium follow through was 0.90 with a specificity 0.96 for the diagnosis of Crohn's disease in the terminal ileum.

Barium Sulfate↗
PubMed1990

Differential expression of CD25 (interleukin-2 receptor) on lamina propria T cells and macrophages in the intestinal lesions in Crohn's disease and ulcerative colitis.

Many interleukin-2 receptor (CD25) bearing cells can be identified by alkaline phosphatase immunohistochemistry in the diseased intestinal lamina propria of children with Crohn's disease or ulcerative colitis, but rarely in normal intestine. In both diseases, the CD25+ cells are present as aggregates in the lamina propria below the epithelium, and constitute a large proportion of the lamina propria mononuclear cells. In Crohn's disease, but not ulcerative colitis, CD25+ cells are abundant in the submucosa. The CD25+ cells in Crohn's disease are 58-88% CD3+, CD4+, CD8-, indicating that they are T cells, whereas in ulcerative colitis the CD25+ cells are greater than 80% CD3-, CD4+, HLA-DR+, indicating that they are macrophages. Thus, differential expression of CD25 on T cells and macrophages serves to distinguish the immunologic lesions in ulcerative colitis and Crohn's disease.

Adolescent↗
PubMed1990

Precancer and cancer in extensive ulcerative colitis: findings among 401 patients over 22 years.

Patients with extensive ulcerative colitis who do not need early surgery have been offered regular examination with the aim of detecting precancerous change (dysplasia) or early colorectal carcinoma. Outpatient visits with clinical examination, sigmoidoscopy, and biopsy were supplemented by two-yearly colonoscopy after the disease course reached 10 years. During the 22 year period from the beginning of 1966 to the end of 1987, 401 patients entered the programme and together contributed 4048 patient-years of observation. Apart from nine patients who left the country, follow up is complete until 1986 or 1987. Colorectal carcinoma developed in 22 patients and, in a further 12, biopsy evidence of precancer, described as severe/high grade dysplasia, was confirmed in a colectomy specimen. The cumulative probability of developing carcinoma was 3% at 15 years, 5% at 20 years, and 9% at 25 years; corresponding figures for precancer or carcinoma, or both were 4%, 7%, and 13%. Five patients died of colorectal carcinoma, two while under regular observation and three after developing carcinoma four to six years after their last attendance. Among the 17 patients who developed carcinoma while under observation, the Dukes stage was A or B in 12. Patients with extensive colitis whose disability does not warrant early surgery have a clinically important cancer risk after the disease has been present for 10 years. Our results suggest that follow up in the manner described reduces the mortality from this complication. Further work is needed to define the optimum method of surveillance and show if it is cost effective.

Adult↗