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Biomedical subjects

J D Potter

Publications and source records attributed to J D Potter.

At least 271 records · Page 15Linked to original sources
PubMed1984

Retrospective assessment of dietary intake.

In studying the role of diet in chronic disease etiology, measurement of past intake may be of more relevance than measurement of that existing either at the time of or just preceding the clinical onset of disease. In 1983, in metropolitan Adelaide, South Australia, estimates of current and previous dietary intake were obtained, by use of a semiquantitative food frequency questionnaire, from 70 individuals (37 male, 33 female), from each of whom an estimate of intake, using the same questionnaire, had been obtained three years earlier. Over this three-year period, median nutrient and energy intake had declined. In relative, if not absolute terms, individuals were able to make satisfactory retrospective estimates of original nutrient and energy intake; however, their retrospective estimates appeared to have been influenced by their current intakes. Nevertheless, the strong correlations observed between retrospective and original estimates of intake suggest that the semiquantitative food frequency method of retrospective dietary assessment allows a reliable relative ranking of individuals by nutrient intake within a population.

Adult↗
PubMed1983

Synthesis, spectral properties, and use of 6-acryloyl-2-dimethylaminonaphthalene (Acrylodan). A thiol-selective, polarity-sensitive fluorescent probe.

Fluorophores processing a 6-acyl-2-dimethylaminonaphthalene moiety show fluorescence that is extremely sensitive to solvent polarity (Weber, G., and Farris, F. J. (1979) Biochemistry 18, 3075-3078). We have synthesized and characterized 6-acryloyl-2-dimethylaminonaphthalene (Acrylodan) which selectively labels thiol moieties in proteins. The quantum yield of this agent is markedly enhanced after reaction with thiols, and as expected, the fluorescent derivatives are very sensitive to dipolar perturbation from their environments. The usefulness of Acrylodan in the study of "hydrophobic" domains, conformational changes, and dipolar relaxation processes in proteins is demonstrated by measurements of fluorescence spectra and lifetimes of a mercaptoethanol adduct dissolved in different solvents and of adducts of this agent with parvalbumin, troponin C, papain, and carbonic anhydrase.

2-Naphthylamine↗
PubMed1983

Large bowel cancer in women in relation to reproductive and hormonal factors: a case-control study.

A community-based case-control study of the effect of reproductive factors on risk of large bowel cancer in Australia is described. The study involved 155 cases (99 colon cancer, 56 rectal cancer) and 311 controls who were interviewed with regard to pregnancies and their outcomes, lactation, menstrual history, and oral contraceptive (OC) use. Increasing parity was associated with a decreasing risk of colon cancer; para 0, relative risk (RR)=1; para 1-2, RR=0.9, 95% confidence interval (CI)=0.4-1.8; para greater than or equal to 3, RR=0.4, 95% CI=0.2-0.8; later age at first live birth (AFLB) was associated with increasing risk (AFLB less than or equal to 21 yr, RR=1; 22-25 yr, RR=2.3, 95% CI=1.0-5.5; greater than or equal to 26 yr, RR=2.7, 95% CI=1.2-6.2). These effects were independent of each other. Parity appeared to exert its predominant effect on risk of cancer of the right colon. OC use was more common among controls than cases (RR=0.5; 95% CI=0.3-1.2 for ever vs. never users) and showed a dose-response effect in multiple logistic analysis. The pattern of point-estimate RR for rectal cancer was largely congruent with those for colon cancer but was not significantly different from 1.0.

Adult↗
PubMed1982

Alcohol and beer consumption in relation to cancers of bowel and lung: an extended correlation analysis.

Some extensions to simple international correlation analyses are examined with reference to beer consumption and bowel and lung cancers in 29 countries. Simple correlation of cross-sectional data for beer consumption and rectal cancer yields a coefficient of 0.77 in males and 0.75 in females. Lagged correlation analyses show a different temporal relationship between beer and colon cancer (little change over time) and rectal cancer (maximal correlation for contemporaneous, i.e. cross-sectional, data sets). Lagged correlation analysis of beer consumption and lung cancer shows a similar pattern to that for rectal cancer and beer, and markedly different from that for lung cancer and cigarettes, the former showing maximal correlation for contemporaneous data, the latter peaking 15 yr prior to date of mortality. Changes in beer consumption over time correlate with subsequent changes in rectal cancer, particularly amongst younger age groups. The sex-ratio of rectal cancer varies from around 1 in low beer consumption countries to about 1.75 in high consumption countries. The utility of these extensions to the usual simple correlation analyses is considered. The biologic plausibility of beer-bowel cancer relationships, and possible mechanisms, are discussed in the light of the findings.

Adult↗
PubMed1982

Fibre in the prevention and management of chronic disease.

Some of the evidence of the role of dietary fibre in the prevention and treatment of disease is reviewed and the heterogeneous nature of fibre is considered. The relationships between various fibre fractions and colonic disorders, including cancer, diabetes mellitus, hypercholesterolaemia and obesity are discussed. It is concluded that an increase of dietary fibre constituents is only one part of a programme of dietary modification relevant to chronic diseases of a Western industrialised society.

Chronic Disease↗
PubMed1981

Fluorescence studies of the interaction of calmodulin with myosin light chain kinase.

The interaction of calmodulin with myosin light chain kinase produces an approximately 30% increase in myosin light chain kinase tryptophan fluorescence. This represents the first report of calmodulin-induced structural changes in a protein which it activates. We fund that the calmodulin-myosin light chain kinase interaction is: 1) dependent on [Ca2+] (half-maximal binding at pCa 6.2) and essentially independent of [Mg2+], 2) occurs before saturation of all four reported Ca2+-specific sites on calmodulin. 3) saturates with 1 mol of calmodulin bound per mol of kinase with an apparent affinity of approximately 2.0 X 10(7) M-1, 4) is specific for calmodulin over troponin-C, 5) is directly related to the activation of myosin light chain kinase for phosphorylation of myosin light chain. Fluorescence stopped flow studies of these calmodulin-induced fluorescence changes in myosin light chain kinase indicate that Ca2+ binding to calmodulin occurs very rapidly and is not rate-limiting while the calmodulin-induced fluorescence increase in myosin light chain kinase occurs as a biphasic process with rates of approximately 65 s-1 and 6 s-1. The fluorescence increase produced by calmodulin binding to myosin light chain kinase is completely reversed by ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid at a rate of approximately 2 s-1.

Animals↗
PubMed1981

Interaction of calmodulin with skeletal muscle myosin light chain kinase.

Studies on myosin light chain kinase isolated from rabbit skeletal muscle show that the enzyme has a molecular weight of 80,000--84,000 with a sedimentation coefficient of 3.2 S and an apparent Stokes radius of 53 A. Gel filtration chromatography with a 3H-labeled calmodulin using a Hummel--Dryer technique shows that the enzyme will bind 1 mol of calmodulin per mol of enzyme, with an affinity of (1.9 +/- 0.5) x 10(7) M-1 in the absence of substrate. The calmodulin dependence of enzyme activation at limiting Mg2+ and light chain concentrations confirms this observation. The calcium dependence of activation of the enzyme--calmodulin complex is characterized by a Hill coefficient of 2.5, with half-activation occurring at 6.6 x 10(-7) M Ca2+. The amino acid composition shows a high percentage (9.1%) of proline, which may account for the large apparent Stokes radius and no clear resemblance to other skeletal muscle proteins. A comparison of the amino acid composition with that from turkey gizzard shows some resemblance.

Animals↗