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Biomedical subjects

R Burt

Publications and source records attributed to R Burt.

At least 37 records · Page 2Linked to original sources
PubMed1993

Mutational analysis of patients with adenomatous polyposis: identical inactivating mutations in unrelated individuals.

Samples of constitutional DNA from 60 unrelated patients with adenomatous polyposis coli (APC) were examined for mutations in the APC gene. Five inactivating mutations were observed among 12 individuals with APC; all were different from the six inactivating mutations previously reported in this panel of patients. The newly discovered mutations included single-nucleotide substitutions leading to stop codons and small deletions leading to frameshifts. Two of the mutations were observed in multiple APC families and in sporadic cases of APC; allele-specific PCR primers were designed for detecting mutations at these common sites. No missense mutations that segregated with the disease were found.

Adenomatous Polyposis Coli↗
PubMed1992

Superior results of ileoanal pull through (IAPT) in polyposis coli vs ulcerative colitis patients.

Colectomy, mucosal proctectomy, and ileoanal pull through (IAPT) have replaced proctocolectomy as the operation of choice in most patients with the colorectal mucosal diseases ulcerative colitis and polyposis coli. This study was conducted to determine whether there is any difference in postoperative morbidity and long-term functional results when IAPT is performed for polyposis coli than when it is performed for ulcerative colitis patients. Between 1982 and 1989, 277 IAPT procedures were performed at the University of Utah Medical Center, 239 for ulcerative colitis and 38 for polyposis coli syndromes. A prospective study compared polyposis and colitis patients after IAPT with regards to age, family history, preoperative findings, operative findings, postoperative complications, and long-term complications. Functional results were compared including day and night stool frequency, incidence of nighttime incontinence, and incidence of pouchitis. The incidence of postoperative complications was lower in the polyposis group than in the colitis group, but the numbers were low enough in both diseases that significant differences were not detected. However, the incidence of pouchitis (0% vs 19%), day (4.2 vs 6.0) and night (0.4 vs 0.9) stool frequency, and nighttime incontinence (5% vs 25%) was significantly lower in the polyposis group when compared to the colitis group. We conclude that IAPT performed for polyposis conditions is associated with superior results when compared with results from patients who undergo the procedure for ulcerative colitis.

Adenomatous Polyposis Coli↗
PubMed1990

Genetic analysis of an inherited predisposition to colon cancer in a family with a variable number of adenomatous polyps.

We studied a large kindred with a history of colorectal cancer of early onset. Proctosigmoidoscopic examination of 51 family members identified only 2 with familial polyposis coli, which strongly predisposes those who have it to colorectal cancer and which is defined as the presence of more than 100 polyps in the colon. However, eight family members had 2 to 40 colonic polyps. We suspected that in this family, colorectal cancer was the result of a mutation in the gene on chromosome 5 that is responsible for familial polyposis coli. To test our hypothesis, we obtained genotypic information on 81 family members with respect to seven polymorphic DNA markers previously shown to be linked to the locus for familial polyposis coli. Multilocus analysis of the data demonstrated genetic linkage (lod score, 5.58) between these markers and the locus responsible for the defined syndrome of colonic polyps or colorectal cancer in this kindred. These findings constitute evidence that the genetic defect in this family is a mutation in the gene that causes familial polyposis coli. We conclude that mutations at the genetic locus for familial polyposis coli may be the cause of other, more subtle syndromes involving an inherited susceptibility to colonic adenomatous polyps and colorectal cancer.

Adenomatous Polyposis Coli↗
PubMed1990

Risk and surveillance of individuals with colorectal polyps. Who Collaborating Centre for the Prevention of Colorectal Cancer.

Since colorectal adenomas are very probably the precursors of colorectal cancer, their detection and removal should result in a decrease in the incidence and mortality from colorectal cancer. Individuals who harbour an adenoma have a 30-50% probability of having additional adenomas at that time, and a 30% probability of having additional adenomas later. Adenomas are prevalent in countries where colorectal cancer is prevalent, about two-thirds of them being tubular and the rest tubulovillous or villous. The initial management of patients with an adenoma consists in searching by colonoscopy the entire colon and removing all additional polyps. Surgical resection is required wherever there is invasive cancer with adverse histological factors. Follow-up in most patients can be after 2-4 years, earlier follow-up being reserved for patients with numerous polyps or with a polyp that had been removed piecemeal. The results of ongoing trials should provide firm guidelines for follow-up and could also be used in mathematical modelling to examine alternative strategies and to help understand the evolving patterns of appearance of new polyps. Finally, a deeper understanding of the biology and inherited and acquired genetics will help identify individuals at risk for adenomas initially and at follow-up. Nutritional factors may also provide a basis for prevention of adenomas in high-risk countries. Many of these issues are being addressed in current research.

Adenoma↗
PubMed1987

The gene for familial polyposis coli maps to the long arm of chromosome 5.

The inherited genetic defect in adenomatous polyposis has been localized to a small region on the long arm of chromosome 5. Sixteen DNA marker loci were used to construct a linkage map of the chromosome. When five kindreds segregating a gene for adenomatous polyposis coli were characterized with a number of the markers, significant linkage was found between one marker and the disease gene. Linkage analysis determined the location of the defective gene within a primary genetic map of chromosome 5.

Chromosome Mapping↗
PubMed1986

Spurious thyroid cancer metastasis: saliva contamination artifact in high dose iodine-131 metastases survey.

The use of high dose 131I for workup of thyroid cancer patients increases the chance of contamination artifact which may mimic metastases. Two elderly male patients with follicular carcinoma of the thyroid had salivary contamination artifacts on metastatic survey scans. These patients received a 1 and 10 mCi dose of 131I, respectively. The artifacts were recognized only retrospectively when follow-up scans were obtained and compared. The characteristics of contamination artifacts and several methods to confirm these are discussed.

Aged↗
PubMed1985

Patterns of peanut agglutinin binding within the developing grasshopper central nervous system.

The location of peanut agglutinin (PNA) binding was investigated in the segmental ganglia of the developing grasshopper embryo. Neuronal processes were stained but cell bodies were not. The first appearance of PNA binding in development was associated with the first neurons to initiate axon outgrowth, the progeny of the MP2 cells. In the early stages of development the location of PNA binding was congruent with that of antibodies against horseradish peroxidase (HRP), which bind to neurons. In more advanced ganglia only a subpopulation of those neuronal processes that bound auti-HRP also bound PNA. The results suggest that PNA-binding sites are present only on those neuronal processes which are still developing and raise the possibility that these molecules may play a rôle in neurite outgrowth and navigation.

Animals↗
PubMed1983

A test of the role of two oncogenes in inherited predisposition to colon cancer.

Inheritance of mutationally altered oncogenes could predispose individuals to the development of specific tumors and account for familial tumor phenotypes. Using adjacent DNA sequence polymorphisms as genetic markers, we have examined two oncogenes, the Kirsten ras2, isolated from a human colon cancer cell line, and the Harvey ras1, isolated from a human bladder cancer cell line, for their role in the genetic etiology of inherited colon cancer in Gardner syndrome. Both oncogene loci have been shown to be unlinked to the Gardner syndrome locus and are, therefore, eliminated as candidates for the Gardner syndrome gene.

Base Sequence↗
PubMed1983

Individual fatty acids in the British household food supply.

The amounts of some 40 fatty acids in British foods, derived from food tables and from a major new analytical survey, have been applied to National Food Survey results to give the average intake of each fatty acid in 1981. The major sources of the more significant fatty acids are also discussed.

Diet Surveys↗
PubMed1983

A blinded prospective study comparing four current noninvasive approaches in the differential diagnosis of medical versus surgical jaundice.

A prospective study was undertaken to compare the diagnostic accuracy of clinical evaluation, ultrasound, computed tomography, and technetium 99m-HIDA or -PIPIDA biliary scans in distinguishing between intrahepatic and extrahepatic jaundice. A final diagnosis was established in each of the 50 patients who completed the study, among whom 29 had intrahepatic cholestasis and 21 had extrahepatic obstruction. In the diagnosis of extrahepatic obstruction, the sensitivities of clinical evaluation, ultrasound, computed tomography, and nuclear medicine biliary scan were 95%, 55%, 63%, and 41%, respectively; the specificities were 76%, 93%, 93%, and 88%; and the overall accuracies were 84%, 78%, 81%, and 68%. These data support the conclusion that when the clinical evaluation is carefully performed, it is the single most effective noninvasive means of detecting extrahepatic biliary obstruction in a jaundiced patient. Although ultrasound, computed tomography, and radionuclide biliary scan are less sensitive, they are highly reliable if they indicate that extrahepatic obstruction is present. A flow chart of invasive and noninvasive approaches for evaluation of the jaundiced patient is presented.

Adult↗
PubMed1982

High-contrast film copying for thallium 201 cardiac image processing.

To evaluate the usefulness of high-contrast film copying as an economical means of enhancing contrast in thallium 201 cardiac images, stress and rest studies of 47 patients with and 19 patients without coronary artery disease were evaluated. A total of 66 sets of four different image formats were independently interpreted by five observers. The analysis of the receiver operating characteristic curves suggested that the high-contrast film copies were superior to their original analog images and comparable with computer-processed images in diagnostic yield. It appears that contrast enhancement by simple film copying can improve the accuracy of 201Tl image interpretation.

Coronary Disease↗
PubMedDate not supplied

Efficacy and safety of an over-the-counter transdermal nicotine patch as an aid for smoking cessation.

OBJECTIVE: To evaluate the efficacy and safety of a transdermal nicotine patch as an aid for smoking cessation in an over-the-counter setting. DESIGN: Multicenter, double-blind, randomized, placebo-controlled trial of 6-week duration with 18 weeks of follow-up. SETTING: Four shopping mall precincts. PARTICIPANTS: The randomized sample consisted of 802 adults (mean age, 39 years) and was 89% white and 54% female. A smoking history of at least 20 cigarettes per day for 1 year and a score of 5 (on a 10-point scale) on a motivational assessment questionnaire were required for enrollment. Poststudy follow-up was limited to those who had quit smoking at the end of 6 weeks. INTERVENTION: Nicotine patches were provided at the shopping mall. Guidance consisted only of package instructions and a smoking cessation self-help booklet. MAIN OUTCOME MEASURES: Quit rates were defined as total abstinence from smoking for 4 consecutive weeks (treatment weeks 3-6), point prevalence smoking status at week 6, or nonsmoker at week 6 and week 24 (6-month postquit date). Smoking status was assessed by diaries, and verification for the first 2 quit rates was obtained by confirmation of carbon monoxide of 8 ppm or less in expired breath. Safety was evaluated by self-reported adverse events. RESULTS: Quit rate was 12% for the active treatment group and 5.5% for the placebo group, based on total abstinence for 4 consecutive weeks (P = .001) compared with quit rates of 19.5% and 7.5% for active treatment and placebo groups, respectively, based on point prevalence data at week 6. At 24 weeks, 8.2% of nonsmokers in the active treatment group and 4.0% in the placebo group remained nonsmokers. At least 1 adverse event was reported by 57% receiving the nicotine patch and 39% receiving placebo (P<.001). CONCLUSIONS: When the nicotine patch was used in an over-the-counter setting, quit rates were comparable to those reported for medical settings. A 2:1 quit rate advantage was achieved at week 6 and was maintained at 24 weeks.

Administration, Cutaneous↗
PubMedDate not supplied

The influence of phenobarbital on biotransformation of 25-hydroxycholecalciferol.

Altered vitamin D metabolism has been implicated as a cause of anticonvulsant-induced osteomalacia. Previous studies have demonstrated accelerated biotransformation of vitamin D3 to 25-hydroxycholecalciferol (25-OHD3). However, it is not known whether the 25-OHD3 is metabolized to 1,25-dihydroxycholecalciferol (1,25-(OH)2D3), the tissue-active metabolite of vitamin D3. This study using rats was undertaken to study the influence of phenobarbital on the biotransformation of 25-OHD3 to 1,25-(OH)2D3. The disappearance rate of 25-OHD3 was virtually the same in the pheno-barbital-treated group (re = 0.0615 pmole/min) and the control group (re - 0.0549 pmole/min). Similarly, the appearance rate of 1,25-(OH)2D3 was virtually the same in the treated group (ra = 0.0133 pmole/min) and the control group (ra = 0.0134 pmole/min). These data suggest that phenobarbital does not affect the biotransformation of 25-OHD3 to 1,25-(OH)2D3. The implication of this observation is that altered vitamin D metabolism does not account for phenobarbital-induced osteomalacia.

Animals↗
PubMedDate not supplied

Major and trace elements of selected pedons in the USA.

Few studies of soil geochemistry over large geographic areas exist, especially studies encompassing data from major pedogenic horizons that evaluate both native concentrations of elements and anthropogenically contaminated soils. In this study, pedons (n = 486) were analyzed for trace (Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Zn) and major (Al, Ca, Fe, K, Mg, Na, P, Si, Ti, Zr) elements, as well as other soil properties. The objectives were to (i) determine the concentration range of selected elements in a variety of U.S. soils with and without known anthropogenic additions, (ii) illustrate the association of elemental source and content by assessing trace elemental content for several selected pedons, and (iii) evaluate relationships among and between elements and other soil properties. Trace element concentrations in the non-anthropogenic dataset (NAD) were in the order Mn > (Zn, Cr, Ni, Cu) > (Pb, Co) > (Cd, Hg), with greatest mean total concentrations for the Andisol order. Geometric means by horizon indicate that trace elements are concentrated in surface and/or B horizons over C horizons. Median values for trace elements are significantly higher in surface horizons of the anthropogenic dataset (AD) over the NAD. Total Al, Fe, cation exchange capacity (CEC), organic C, pH, and clay exhibit significant correlations (0.56, 0.74, 0.50, 0.31, 0.16, and 0.30, respectively) with total trace element concentrations of all horizons of the NAD. Manganese shows the best inter-element correlation (0.33) with these associated total concentrations. Total Fe has one of the strongest relationships, explaining 55 and 30% of the variation in total trace element concentrations for all horizons in the NAD and AD, respectively.

Geological Phenomena↗