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Biomedical subjects

D Duncan

Publications and source records attributed to D Duncan.

At least 37 records · Page 2Linked to original sources
PubMed1998

Recognition of intussusception around gastrojejunostomy tubes in children.

OBJECTIVE: We describe antegrade intussusceptions of duodenum and jejunum around gastrojejunostomy tubes seen on sonography and fluoroscopic contrast tube studies. Reduction of the intussusception was achieved by bolus injection of air or contrast medium through the tube or exchange over a wire. CONCLUSION: Sonography and fluoroscopic contrast tube studies permit diagnosis of intussusception around gastrojejunostomy tubes.

Child, Preschool↗
PubMed1997

Dietary energy sources and colon cancer risk.

Because energy-contributing nutrients are highly correlated with total energy, the association with colon cancer from energy versus other components of energy-providing nutrients is often not clear. Dietary data from a population-based case-control study of colon cancer were analyzed in subjects from California, Utah, and Minnesota in 1991-1994 to assess the colon cancer risk associated with consumption of energy, fat, protein, and carbohydrate. After adjustment for long-term physical activity, total energy intake increased risk of colon cancer in men (odds ratio = 1.74, 95% confidence interval 1.14-2.67 for highest vs. lowest quartile) and in women (odds ratio = 1.70, 95% confidence interval 1.07-2.70). Various methods of analysis suggested that intakes of individual sources of energy (dietary fat, protein, and carbohydrate) were not associated with colon cancer risk after total energy intake was taken into account. People who consumed a high-calorie diet that was dense in fiber and calcium appeared to be at lower risk than people with the same caloric intake who consumed smaller amounts of dietary fiber and calcium. Individuals with a first-degree relative with colorectal cancer, especially those diagnosed at a younger age, were at a greater risk from a diet high in energy than were individuals without a family history of colorectal cancer.

Adult↗
PubMed1997

Hepatic necrosis masquerading as trauma.

We report the case of a child who had deterioration of hepatic function 3 days after suffering a depressed compound skull fracture with underlying brain contusion. An abdominal enhanced CT scan revealed a wedge-shaped region of devitalised liver with associated free intraperitoneal fluid, consistent with a traumatic lesion but due to necrosis secondary to acetaminophen toxicity. Acetaminophen toxicity may occur with therapeutic doses in the presence of an ischaemic hepatitis. Any delay in the performance of CT from the time of trauma should prompt the consideration of alternative diagnoses.

Acetaminophen↗
PubMed1997

Knowledge of New Zealand youth regarding sexuality and AIDS.

A questionnaire (99 questions) was used to gather baseline data on New Zealand youth regarding sexuality and AIDS. The sample consisted of 560 students ranging in age from 12 to 18 years. Findings on general sexual knowledge and AIDS knowledge (15 questions) are reported. There is room for improvement in sexuality education of New Zealand youth.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Dietary sugar and colon cancer.

It has been hypothesized that levels of triglycerides, glucose, and insulin are associated with risk of colon cancer and that diets high in simple sugars increase risk of colon cancer because of their impact on these factors. Limited epidemiological evidence supports the association between simple carbohydrates and risk of colon cancer. Using data from a population-based case-control study (n = 1993 cases and 2410 controls), we examined the associations between dietary sugars, foods containing high level of sugars, and dietary glycemic index (GI) and colon cancer. A dietary GI was developed to estimate metabolic response to a diet that may increase plasma glucose levels. Dietary data were obtained using a validated diet history questionnaire. High levels of sucrose intake were associated with increased risk of colon cancer among younger men [odds ratio (OR) for highest quintile relative to lowest, 1.59; 95% confidence interval (CI), 1.07-2.37]. There was also a trend of increasing colon cancer risk associated with a higher sucrose:dietary ratio for proximal tumors in both men and women. Individuals with proximal tumors who consumed a diet ranked as having a high GI were at increased risk (for men, comparing highest quintile to lowest quintile: OR, 1.58; 95% CI, 1.06-2.36; P trend 0.04; for women: OR, 1.72; 95% CI, 1.11-2.67; P trend 0.04). Those at greatest risk from a high dietary GI were those who were sedentary (for men, relative to those who were most active and had a low-GI diet: OR, 3.46; 95% CI, 1.78-6.70; for women: OR, 2.00; 95% CI, 0.98-4.07). We also observed that people who had a high sucrose: dietary fiber ration and who also were sedentary and had a large body mass index were at increased risk (OR, 4.58; 95% CI, 2.33-8.98) relative to those who had a low sucrose:dietary fiber ratio, were active, and had low body mass indices. These findings support previous reports that dietary sugars, especially diet high in simple carbohydrates relative to complex carbohydrates, increase risk of colon cancer, possibly through their impact on plasma glucose levels.

Adult↗
PubMed1996

Randomized controlled trial of a low animal protein, high fiber diet in the prevention of recurrent calcium oxalate kidney stones.

Low protein diets are commonly prescribed for patients with idiopathic calcium nephrolithiasis, who account for > 80% of new diagnoses of kidney stones. This dietary advice is supported by metabolic studies and epidemiologic observational studies but has not been evaluated in a controlled trial. Using 1983-1985 data from three Northern California Kaiser Permanente Medical Centers, the authors randomly assigned 99 persons who had calcium oxalate stones for the first time to a low animal protein, high fiber diet that contained approximately 56-64 g daily of protein, 75 mg daily of purine (primarily from animal protein and legumes), one-fourth cup of wheat bran supplement, and fruits and vegetables. Intervention subjects were also instructed to drink six to eight glasses of liquid daily and to maintain adequate calcium intake from dairy products or calcium supplements. Control subjects were instructed only on fluid intake and adequate calcium intake. Both groups were followed regularly for up to 4.5 years with food frequency questionnaires, serum and urine chemistry analysis, and abdominal radiography; and they were urged to comply with dietary instructions. In the intervention group of 50 subjects, stones recurred in 12 (7.1 per 100 person-years) compared with two (1.2 per 100 person-years) in the control group; both groups received a mean of 3.4 person-years of follow-up (p = 0.006). After adjustment for possible confounding effects of age, sex, education, and baseline protein and fluid intake, the relative risk of a recurrent stone in the intervention group was 5.6 (95% confidence interval 1.2-26.1) compared with the control group. The authors conclude that advice to follow a low animal protein, high fiber, high fluid diet has no advantage over advice to increase fluid intake alone.

Adult↗
PubMed1996

Functional expression of human topoisomerase II alpha in yeast: mutations at amino acids 450 or 803 of topoisomerase II alpha result in enzymes that can confer resistance to anti-topoisomerase II agents.

DNA topoisomerase II is the target of a variety of important antitumor agents, including etoposide, adriamycin, and amsacrine. We have constructed a system for analyzing the action of anti-topoisomerase II agents using the yeast Saccharomyces cerevisiae and have constructed vectors for expressing human topoisomerase II functionally in yeast. We have demonstrated that temperature-conditional yeast TOP2 mutants can be complemented by expression of wild-type human topoisomerase II alpha. Furthermore, expression of human topoisomerase II in yeast results in a quantitatively unique pattern of sensitivity to amsacrine. We also have constructed mutations in human TOP2 based on previously identified mutations from a human cell line selected for resistance to teniposide. Our experiments demonstrate that mutation of either arginine 450 or proline 803 of human topoisomerase II can result in an enzyme that has altered sensitivity to anti-topoisomerase II agents, and that a human enzyme carrying both mutations confers a higher level of drug resistance than enzymes carrying either single mutation.

Alleles↗
PubMed1995

Molecular modeling of the GM-CSF and IL-3 receptor complexes.

A model for the structure of the cytokine interleukin-3 (IL-3) is presented based on the structural homology of the hematopoietic cytokines and utilizing the crystal structures of interleukin-5 and granulocyte macrophage colony stimulating factor (GM-CSF). In addition, models of the receptor complexes of GM-CSF and IL-3 are presented based on the structural homology of the hematopoietic receptors to growth hormone. Several key interactions between the ligands and their receptors are discovered, some in agreement with previous mutagenesis studies and others that have not yet been the subject of mutagenesis studies. The models provide insights into the binding of GM-CSF and IL-3 to their receptors.

Amino Acid Sequence↗
PubMed1995

Transvection in the iab-5,6,7 region of the bithorax complex of Drosophila: homology independent interactions in trans.

The Abdominal-B (Abd-B) gene of the bithorax complex (BX-C) of Drosophila controls the identities of the fifth through seventh abdominal segments and segments in the genitalia (more precisely, parasegments 10-14). Here we focus on iab-5, iab-6 and iab-7, regulatory regions of Abd-B that control expression in the fifth, sixth and seventh abdominal segments (parasegments 10-12). By analysis of partial BX-C deficiencies, we show that these regions are able to promote fifth and sixth abdominal segment identities in the absence of an Abd-B gene in cis. We establish that this ability does not result from cis-regulation of the adjacent abd-A or Ubx genes of the BX-C but rather occurs because the iab-5,6,7 region is able to interact with Abd-B in trans. We demonstrate that this interaction is proximity dependent and is, therefore, a case of what E. B. Lewis has called transvection. Interactions of this type are presumably facilitated by the synapsis of homologues that occurs in somatic cells of Dipterans. Although transvection has been detected in a number of Drosophila genes, transvection of the iab-5,6,7 region is exceptional in two ways. First, interaction in trans with Abd-B does not require that homologues share homologous sequences within, or for some distance to either side of, the BX-C. This is the first case of transvection shown to be independent of local synapsis. A second unusual feature of iab-5,6,7 transvection is that it is remarkably difficult to disrupt by heterozygosity for chromosome rearrangements. The lack of requirement for local synapsis and the tenacity of trans-interaction argue that the iab-5,6,7 region can locate and interact with Abd-B over considerable distance. This is consistent with the normal role of iab-5,6,7, which must act over some 20-60 kb to influence its regulatory target in cis at the Abd-B promoter. Evidence is presented that trans-action of iab-5,6,7 requires, and may be mediated by, the region between distal iab-7 and Abd-B. Also, we show that iab-5,6,7 transvection is independent of the allelic state of zeste, a gene that influences several other cases of transvection. The long-range nature of interactions in trans between iab-5,6,7 and Abd-B suggests that similar interactions could operate effectively in organisms lacking extensive somatic pairing. Transvection may, therefore, be of more general significance than previously suspected.

Abdomen↗
PubMed1994

A computerized diet history questionnaire for epidemiologic studies.

OBJECTIVE: To describe methods used to computerize the diet history questionnaire developed for the Coronary Artery Risk Factor Development in Young Adult (CARDIA) study and to describe quality-control procedures used in conjunction with dietary assessment. DESIGN: The computerized diet history is being used in a case-control study. Because of the computerized nature of the questionnaire, we developed quality-control procedures that incorporate listening to an audiotape of the interview while visually reviewing recorded data. SETTING: Three centers involved in a population-based epidemiologic study of colon cancer. SUBJECTS: Men and women between the ages of 30 and 79 years. RESULTS: Quality-control results showed that 100% of the computerized forms would be free of errors if the data were subjected to visual review only. Probing errors, which accounted for 47.3% of all errors, were the most commonly encountered errors. In probing errors the interviewer did not probe in a nondirective manner, or the interviewer failed to verify responses that might be considered questionable. APPLICATIONS: The CARDIA diet history was computerized for use in epidemiologic studies of the association between diet and disease. Review of the audiotapes of the interviews showed that most errors made in obtaining a dietary assessment were not detectable from visual review of the data. Although the quality-control procedures were developed for a computerized diet history questionnaire, they are applicable to other dietary assessment methods.

Adult↗
PubMed1994

Predictive modelling of the 3-D structure of interleukin-13.

Several atomic structures are now available for the family of helical cytokines, which includes growth hormone as well as many of the interleukins. Using structural information from five members of this family, two alternative models of interleukin (IL)-13 are proposed. IL-13 has biological properties similar to those of IL-4 and, like the other interleukins, is a potentially important pharmaceutical target. The model of IL-13 is discussed and compared with the known interleukin structures.

Amino Acid Sequence↗
PubMed1993

Unfolding and refolding of the NAD(+)-dependent isocitrate dehydrogenase from yeast.

The unfolding of the NAD(+)-dependent isocitrate dehydrogenase from yeast in guanidinium chloride (GdnHCl) has been monitored by changes in c.d. and fluorescence. Major structural changes occur over the range of GdnHCl concentrations from 0.5 to 1.5 M, although loss of catalytic activity is complete at 0.3 M. After incubation in GdnHCl, activity can be regained on dilution; however, the extent of this regain is dependent on the initial concentration of GdnHCl and is very small at a concentration of 2 M or above. Under these conditions there is only limited regain of the secondary and tertiary structure of the enzyme. Considerably more structure and activity can be regained if the concentration of GdnHCl is lowered by dialysis. The implications of these results for the folding and assembly of the enzyme are discussed.

Circular Dichroism↗