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Fourteen subjects between 7 and 17 years of age with an equal distribution of low and high caries activity were given: (1) a 10% sucrose rinse, (2) a reference candy, (3) a reference candy with 3% dicalcium phosphate dihydrate, and (4) a reference candy with 0.75% calcium lactate on four different occasions. Plaque samples were collected before and at 15-min intervals after the sucrose rinse or food challenge for a period of 1 h on each occasion. Plaque samples were centrifuged and the extracellular plaque fluid analysed by a microtechnique for pH, total calcium and inorganic phosphorus concentration. There was no significant increase in calcium and phosphorus in plaque fluid for the group using candy with added calcium compared to the reference candy or sucrose rinse. There was no significant difference between the measurements in subjects grouped as caries active or inactive. The results suggest no benefit can be expected from adding dicalcium phosphate dihydrate and calcium lactate to candy to decrease demineralization during a cariogenic challenge.
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Influence of bioactive food supplements (BFA) intake on intestinal barrier permeability to macromolecules of polyethylene glycol 4000 was studied in rats with intestinal anaphylaxis and after external gamma-irradiation. BFA studied included autolysed baker's yeast ("Vitasil") and edible algae Spirulina platensis. Intake of complex additive Vitasil + Spirulina resulted in significant diminution of permeability before irradiation and its partial normalization (24% decrease) after irradiation. Spirulina additive intake led to practically complete normalization of permeability (1.84 times decrease) in anaphylactic rats. It is concluded that Spirulina and Vitasil are promising BFA for organism general resistance elevation.
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The four components of the process by which a decision is made about the acceptability of human exposure to a chemical are outlined. The quantity and quality of the data that are required have increased considerably in recent years, and the standards governing the conduct of the studies done to obtain them have become more stringent. Thus, many chemicals now in widespread use were admitted on the basis of evidence that is now considered woefully inadequate; the steps being taken in the US to remedy this situation are described. Since such testing is long and expensive, four regulatory agencies have joined together to develop guidelines that can be used by each. The interpretation of data presents yet another problem. Further, what constitutes adequate evidence for safety is a matter subject to wide ranges of opinion: this is illustrated by the example of cyclamate. The difficulties of extrapolating results to actual situations are outlined; and the limitations of the usefulness of experimental testing are pointed out. Determination of an acceptable ratio between benefits and risks depends on a wide variety of factors, and regulatory decisions in this regard thus depend on several kinds of scientific judgements and on policy decisions based on cultural aspects.
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Emerging evidence has suggested environmental factors as causative agents in the pathogenesis of primary biliary cirrhosis (PBC). We have hypothesized that in PBC the lipoyl domain of the immunodominant E2 component of pyruvate dehydrogenase (PDC-E2) is replaced by a chemical xenobiotic mimic, which is sufficient to break self-tolerance. To address this hypothesis, based upon our quantitative structure-activity relationship data, a total of 107 potential xenobiotic mimics were coupled to the lysine residue of the immunodominant 15 amino acid peptide of the PDC-E2 inner lipoyl domain and spotted on microarray slides. Sera from patients with PBC (n = 47), primary sclerosing cholangitis (n = 15), and healthy volunteers (n = 20) were assayed for Ig reactivity. PBC sera were subsequently absorbed with native lipoylated PDC-E2 peptide or a xenobiotically modified PDC-E2 peptide, and the remaining reactivity analyzed. Of the 107 xenobiotics, 33 had a significantly higher IgG reactivity against PBC sera compared with control sera. In addition, 9 of those 33 compounds were more reactive than the native lipoylated peptide. Following absorption, 8 of the 9 compounds demonstrated cross-reactivity with lipoic acid. One compound, 2-octynoic acid, was unique in both its quantitative structure-activity relationship analysis and reactivity. PBC patient sera demonstrated high Ig reactivity against 2-octynoic acid-PDC-E2 peptide. Not only does 2-octynoic acid have the potential to modify PDC-E2 in vivo but importantly it was/is widely used in the environment including perfumes, lipstick, and many common food flavorings.
Polysaccharide mixtures used as stabilizers having identical sugar units, but differing in their linkages can be identified with confidence by means of methylation analysis. Such mixtures are methylated with sodium hydride and methyl iodide in anhydrous dimethylsulfoxide. The methylated products are acid hydrolyzed and the resulting methyl sugars are separated and identified by thinlayer- or gaschromatography.
Nitrogen conversion factors for gum arabic (Acacia senegal (L.) Willd.), gum tragacanth (Asiatic Astragalus spp.), gum karaya (Sterculia spp.), guar gum (Cyamopsis spp.), locust bean (carob) gum (Ceratonia spp.), tara gum (Caesalpinia spp.), and xanthan gum (Xanthomonas campestris) have been calculated from data for the amino acid compositions of their proteinaceous components. The factors derived differ from the arbitrary values (5.7 or 6.25) at present specified by international regulatory authorities for some emulsifiers, stabilizers and thickeners.
A new coating for cheese, to be introduced in May, consists entirely of natural degradable components. The coating is based on wheat gluten. This increase in the amount of gluten in the Dutch diet may lead to overt coeliac disease in people with a subclinical form of it, and will limit the dietary choices of patients already suffering from the disease.
The effects of different heating systems on the heat resistance of Bacillus stearothermophilus spores (ATCC 7953, 12980, 15951 and 15952) were investigated. Spores were heated in distilled water, Sorensen buffer (0.18 mol 1-1), McIlvaine buffer (0.0025-0.18 mol 1-1), and several solutions containing sodium chloride (0.06-12%), sodium nitrite (125 ppm), potassium sorbate (0.1%) and sodium benzoate (0.1%) over a wide range of temperatures (115-140 degrees C). D-values obtained for McIlvaine and Sorensen buffers, at the same molarities, were not significantly different (P > 0.05), but decimal reduction times increased as phosphate concentrations in the solutions decreased. The concentrations, in which statistically significant differences (P < 0.05) were obtained, varied among strains. Among the additives assayed, only sodium chloride reduced heat resistance, being effective at concentrations as low as 0.06%. The z-values calculated in this study ranged from 6.99 to 8.40 with a mean value of 7.60 +/- 0.45. Although z-values observed for salt and buffers (180 mol 1-1) were slightly higher than obtained in the other conditions assayed, the difference was not statistically significant (P > 0.05).
The acute cytotoxicity of butylated hydroxytoluene and butylated hydroxyanisole to cultured human dermal fibroblasts, keratinocytes, melanocytes, and melanoma tumor cells was determined with the neutral red assay. For all cell types, butylated hydroxytoluene proved to be more cytotoxic than butylated hydroxyanisole. The neutral red assay is a rapid, economical, semiautomated assay that can be used with a variety of cell types in culture to provide quantitated data that can be used to rank test agents according to their potencies.
Toxicology is based on the premise that all compounds are toxic at some dose. Thus, it is not surprising that very large doses of aspartame (or its components--aspartate, phenylalanine, and methanol) produce deleterious effects in sensitive animal species. The critical question is whether aspartame ingestion is potentially harmful to humans at normal use and potential abuse levels. This paper reviews clinical studies testing the effects of various doses of aspartame upon blood levels of aspartate, phenylalanine, and methanol. These studies demonstrate that blood levels of these compounds are well below levels associated with adverse effects in sensitive animal species.