Role of Streptococcus mutans in human dental decay.

A dynamic approach to predicting bacterial growth in food

Food fermentations: role of microorganisms in food production and preservation.

The mucosal immune system : from fundamental concepts to vaccine development

Epidemiological studies have clearly shown that whole-grain cereals can protect against obesity, diabetes, CVD and cancers. The specific effects of food structure (increased satiety, reduced transit time and glycaemic response), fibre (improved faecal bulking and satiety, viscosity and SCFA production, and/or reduced glycaemic response) and Mg (better glycaemic homeostasis through increased insulin secretion), together with the antioxidant and anti-carcinogenic properties of numerous bioactive compounds, especially those in the bran and germ (minerals, trace elements, vitamins, carotenoids, polyphenols and alkylresorcinols), are today well-recognised mechanisms in this protection. Recent findings, the exhaustive listing of bioactive compounds found in whole-grain wheat, their content in whole-grain, bran and germ fractions and their estimated bioavailability, have led to new hypotheses. The involvement of polyphenols in cell signalling and gene regulation, and of sulfur compounds, lignin and phytic acid should be considered in antioxidant protection. Whole-grain wheat is also a rich source of methyl donors and lipotropes (methionine, betaine, choline, inositol and folates) that may be involved in cardiovascular and/or hepatic protection, lipid metabolism and DNA methylation. Potential protective effects of bound phenolic acids within the colon, of the B-complex vitamins on the nervous system and mental health, of oligosaccharides as prebiotics, of compounds associated with skeleton health, and of other compounds such as alpha-linolenic acid, policosanol, melatonin, phytosterols and para-aminobenzoic acid also deserve to be studied in more depth. Finally, benefits of nutrigenomics to study complex physiological effects of the 'whole-grain package', and the most promising ways for improving the nutritional quality of cereal products are discussed.

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New hypotheses for the health-protective mechanisms of whole-grain cereals: what is beyond fibre?

A generalized theory of growth is presented based upon three postulates. The first asserts that the rate of growth is jointly proportional to a monotonic function of the generalized distance from the origin to present size (“reproductive capability”), and to a monotonic function of the generalized distance from present size to ultimate size (“limiting factor”). The second postulate restricts the monotonic function to power (or “mass action”) functions. The third postulate constrains the model to a mathematically tractable set which never-the-less is sufficiently general to include the cases of Malthusian, Gompertz, logistic and Bertalanffy-Richards Growth. The most general case is termed the “generic growth model”. Other special cases are termed hyperGompertzian and hyperlogistic growth. Generic growth is illustrated by rat weight data from the literature.

A theory of growth

Specific assays for peroxidases in human saliva.

The Lactoperoxidase System: Chemistry and Biological Significance

Quantitative, standardized assays for determining the concentrations of bovine lactoperoxidase, human salivary peroxidase, and human myeloperoxidase.

Human salivary peroxidase (SPO) has been purified to homogeneity by subjecting human parotid saliva to immunoaffinity, cation exchange, and affinity chromatography. These procedures resulted in a 992-fold purification of the enzyme. When purified SPO was subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), three Coomassie stainable bands were apparent, all of which stained positive for enzyme activity. The apparent molecular weights of the three bands were 78,000, 80,000, and 280,000 as analyzed by SDS-PAGE. Reduction with 2-mercaptoethanol resulted in a decreased mobility of these bands, and enzyme activity could no longer be detected on the gels. The SPO preparation had the characteristic peroxidase heme spectrum in the range 405-420 nm. The ratio between the absorbance of the Soret band (412 nm) and the absorbance at 280 nm was 0.81. The enzyme activity was inhibited by the classical peroxidase inhibitors cyanide and azide. Salivary peroxidase is similar to bovine lactoperoxidase (LPO) in amino acid composition, in ultraviolet and visible spectrum, in reaction with cyanide, in susceptibility to 2-mercaptoethanol inactivation, and in thermal stability. The two enzymes differ in carbohydrate composition and content. SPO contains 4.6% and LPO 7% total neutral sugars. The ratio of glucosamine to galactosamine is 2:1 in SPO and 3:1 in LPO. SPO contains mannose, fucose, and galactose in a molar ratio of 1.5:1.5:1.0, while the ratio was 14.9:0.5:1.0 in LPO. Glucose was present in both preparations in minor amounts. The concentration of azide required for 50% inhibition of enzyme activity was 20-fold greater for LPO than for SPO.(ABSTRACT TRUNCATED AT 250 WORDS)

Kenneth M. Pruitt

Papers

A theory of growth

Specific assays for peroxidases in human saliva.

The Lactoperoxidase System: Chemistry and Biological Significance

Quantitative, standardized assays for determining the concentrations of bovine lactoperoxidase, human salivary peroxidase, and human myeloperoxidase.

Purification and characterization of human salivary peroxidase.