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Biomedical subjects

J E Heinze

Publications and source records attributed to J E Heinze.

13 recordsLinked to original sources
PubMed1988

Washing with contaminated bar soap is unlikely to transfer bacteria.

Recent reports of the isolation of microorganisms from used soap bars have raised the concern that bacteria may be transferred from contaminated soap bars during handwashing. Since only one study addressing this question has been published, we developed an additional procedure to test this concern. In our new method prewashed and softened commercial deodorant soap bars (0.8% triclocarban) not active against Gram-negative bacteria were inoculated with Escherichia coli and Pseudomonas aeruginosa to give mean total survival levels of 4.4 X 10(5) c.f.u. per bar which was 70-fold higher than those reported on used soap bars. Sixteen panelists were instructed to wash with the inoculated bars using their normal handwashing procedure. After washing, none of the 16 panelists had detectable levels of either test bacterium on their hands. Thus, the results obtained using our new method were in complete agreement with those obtained with the previously published method even though the two methods differ in a number of procedural aspects. These findings, along with other published reports, show that little hazard exists in routine handwashing with previously used soap bars and support the frequent use of soap and water for handwashing to prevent the spread of disease.

Adult↗
PubMed1985

Prediction of the eye irritation potential of shampoos using the in vitro SIRC cell toxicity test.

Shampoos predicted to vary over a wide range in their potential to cause eye irritancy were tested in SIRC rabbit corneal cells for cytotoxicity. Six shampoos at at least ten different concentrations were added to culture dishes containing the SIRC cells and were administered at a dose of 0.01 ml directly to the corneal surface of the albino rabbit eye. When the shampoos were ranked both according to their relative toxicities in vitro and according to their relative irritancies in the modified Draize test the resulting rank orders were in perfect agreement. The results demonstrate that the SIRC cell line is a suitable model system for screening shampoos of differing surfactant compositions without the need to use live animals. Further, results obtained from the SIRC cell assay should aid in the selection of final product formulations for in vivo testing as part of the pre-market clearance process.

Animals↗
PubMed1984

Surfactants: a survey of short-term genotoxicity testing.

The available results for tests on over 200 surfactants in nine short-term genotoxicity assay systems were reviewed. These tests included the Salmonella/microsome mutation assay, bacterial DNA repair tests, mitotic recombination in Saccharomyces cerevisiae, the mouse lymphoma cell-mutation assay, unscheduled DNA synthesis and sister chromatid exchange assays in mammalian cells, mammalian chromosome damage tests in vitro and in vivo, the dominant lethal test in rodents, and mammalian cell-transformation tests. The collected data cover all four major classes of surfactants: anionic, cationic, nonionic and amphoteric. The results of these genotoxicity tests were overwhelmingly negative. Although there were occasional positive results in bacterial or cell-transformation systems, the testing performed to date indicates that surfactants have negligible potential to cause genetic damage. The available data also indicate that none of the assays were incompatible with testing surfactants for genotoxicity.

Animals↗
PubMed1982

Evaluation of an in vitro cell toxicity test using rabbit corneal cells to predict the eye irritation potential of surfactants.

Surfactants reported to be severely, moderately or non-irritating to the eyes of albino rabbits were tested for cell toxicity in vitro using an established line of rabbit corneal cells. Test substances at different concentrations were added to culture dishes containing the rabbit corneal cells or were administered at a dose of 0.01 ml directly to the corneal surface of albino rabbits. A significant rank correlation (r = 0.90, P less than 0.01) was seen between the relative toxicity produced in vitro and the relative eye irritation produced in the modified Draize test. The in vitro method offers a means for screening potentially irritating chemicals without using live animals and may be useful in the selection of product formulations for in vivo testing.

Animals↗
PubMed1979

Partial purine deprivation causes sporulation of Bacillus subtilis in the presence of excess ammonia, glucose and phosphate.

In strains of Bacillus subtilis able to synthesize purines de novo, massive sporulation is suppressed by the combination of excess ammonia, glucose and phosphate. Purine auxotrophs, blocked in the general or the guanine-specific portion of the branched purine pathway, sporulated in such a medium when the purine required for normal growth was removed from the medium. The resulting spore titre and the sporulation frequency increased with the residual growth rate in the purine-free medium, i.e. with the leakiness of the purine mutation. Sporulation was further increased by allowing residual growth in growth-limiting amounts of guanosine. None-leaky purine mutants blocked before 5'-phosphoribosyl-5-amino-4-imidazole carboxamide also sporulated well when supplied with 5-amino-4-imidazole carboxamide at concentrations (2 mM) that supported growth at a suboptimal rate.

Ammonia↗
PubMed1978

Induction of sporulation by inhibitory purines and related compounds.

Sporulation of Bacillus subtilis can be induced, in the presence of excess ammonia, glucose and phosphate, by many purine derivatives under conditions of partial growth inhibition. Some of the compounds are known inhibitors of purine nucleotide synthesis. For most compounds the effect is counteracted by adenine and guanine. Partial growth inhibition by amethopterin (methotrexate) causes sporulation in the absence of purines but not in their presence. Unable to induce sporulation at any concentration are inhibitors of DNA, RNA, and protein synthesis as well as base or amino acid analogs that are incorporated into these polymers.

Bacillus subtilis↗
PubMed1975

The effects of organic solvents on Escherichia coli DNA polymerase III.

The polymerizing ability of Escherichia coli DNA polymerase III is enhanced by a variety of water-miscible organic solvents of which dimethyl sulfoxide at 17% (v/v) is the most effective tested. The extent of stimulation depends on the organic solvent used and its concentration, but shows no obvious correlation with the chemical structure of the solvent or its dielectric constant. Kinetic studies indicate that the mechanism of stimulation is complex.

Acetone↗
PubMed1975

Specificity of the antiviral agent calcium elenolate.

Calcium elenolate, an antiviral agent which inhibits reverse transcriptases, inhibits the growth of chicken embryo fibroblast cells, as well as Echerichia coli and Bacillus subtilis strains. The drug in vitro inhibits E. coli deoxyribonucleic acid (DNA) polymerase II and DNA polymerase III holoenzyme, as well as several unrelated enzymes. The usual DNA polymerase assay components, with the exception of spermidine, have no effect on the observed inhibition. Inhibition of DNA polymerase II by the drug appears to be due to a direct and irreversible effect on the enzyme. However, DNA synthesis in E. coli is no more susceptible to the drug than is the increase in cell mass. These results suggest that calcium elenolate is an inhibitor of rather low specificity.

Animals↗
PubMedDate not supplied

The optimal design of batteries of short-term tests for detecting carcinogens.

The optimal design of a battery of short-term tests for detecting carcinogens has been explored by constructing tables describing the theoretical accuracy of various batteries of tests. The analysis has revealed that the expected accuracy of the testing battery is greatly influenced by the design of the battery, particularly by the number of tests in the battery and by the number of tests which must give a positive result before the compound is considered positive in the battery. The recommended optimal design is not affected by the expected accuracy of the tests comprising the battery, at least not for reasonably accurate short-term tests. Two types of analyses of published data have been presented in support of these theoretical considerations. The first is a statistical analysis (chi-square test) showing that most short-term tests independently detect carcinogens and noncarcinogens, thus fulfilling a key assumption for the use of batteries of short-term tests to improve the detection of carcinogens and noncarcinogens. The second comes from the results of a recent international collaborative study showing that the recommended design of testing batteries would optimize the identification of carcinogens and noncarcinogens by five of the most accurate tests in the study.

Animals↗