PubMed Health⌕ Search

Biomedical subjects

H Babich

Publications and source records attributed to H Babich.

At least 55 records · Page 3Linked to original sources
PubMed1986

In vitro cytotoxicity testing of aquatic pollutants (cadmium, copper, zinc, nickel) using established fish cell lines.

The cytotoxicity of cadmium toward cultured bluegill fry (BF-2) cells was determined using several assay endpoints. The concentrations of cadmium causing a 50% decrease in colony formation, cell replication, uptake of neutral red, population growth (as determined by protein analysis), and uptake of [3H]uridine and 50% detachment of cells (as determined by protein analysis) were 0.03, 0.04, 0.08, 0.09, 0.12, and 0.21 mM cadmium, respectively. The neutral red assay was used to compare the relative sensitivities of bluegill BF-2 cells and RTG-2 cells, derived from the rainbow trout, toward four metals. The concentrations of cadmium, zinc, copper, and nickel causing a 50% reduction in the uptake of neutral red were 0.08, 0.19, 0.55, and 2.0 mM, respectively, with the BF-2 cells and 0.18, 0.64, 1.45, and greater than 10.0 mM, respectively, with the RTG-2 cells. The RTG-2 cells were less sensitive to the metals, in particular to nickel. The less stringent temperature requirements for growth, their greater sensitivity to pollutants, and their markedly shorter doubling time in vitro make the BF-2 cells the preferable cell line for ecotoxicity screening of aquatic pollutants.

Animals↗
PubMed1985

Heavy metal toxicity to microbe-mediated ecologic processes: a review and potential application to regulatory policies.

Microorganisms are sensitive to heavy metal pollution as are other components of the biota. However, most studies on the interactions between microbes and heavy metals have been conducted in synthetic media or in altered (e.g., sterilized) environmental samples and usually have used only single species. Few studies have evaluated the effects of heavy metals on the activities of natural heterogeneous microbial populations, both autotrophic and heterotrophic, in terrestrial and aquatic environments. These latter studies have shown that heavy metals inhibit primary productivity, nitrogen fixation, the mineralization of carbon, nitrogen, sulfur, and phosphorus, litter decomposition, and enzyme synthesis and activity in soils, sediments, and surface waters. The potential adverse effects of heavy metals on such microbe-mediated ecologic processes need to be incorporated into the methodologies used by regulatory agencies, such as the U.S. Environmental Protection Agency, to prepare environmental risk assessments which, in turn, are used to formulate environmental criteria, such as the Water Quality Criteria, and to evaluate the safety to the environment of exposure to "new chemical substances," as mandated by the U.S. Toxic Substances Control Act of 1976. To provide appropriate data that can be assimilated into regulatory policy, it is essential that microbial ecotoxicity tests be standardized, are neither costly nor difficult to train personnel to conduct, and produce data that can be quantitated.

Bacteria↗
PubMed1985

The mediation of mutagenicity and clastogenicity of heavy metals by physicochemical factors.

Heavy metals are an important class of environmental hazards, and as the use of heavy metals metals in industry continues to increase, larger segments of the biota, including human beings, will be exposed to increasing levels of these toxicants. As many heavy metals are mutagenic and clastogenic, they cause teratogenic and/or carcinogenic effects. Studies with microbes and representatives of the aquatic biota have shown that the toxicity of heavy metals is mediated by the physicochemical characteristics of natural environments. A few studies have also indicated that such abiotic factors (e.g. pH, chelating agents, inorganic anionic and cationic composition) mediate the mutagenicity and clastogenicity of heavy metals. These studies indicate that the physicochemical characteristics of natural environments may also potentiate or attenuate the mutagenicity and clastogenicity of heavy metals to the indigenous biota. Furthermore, studies with laboratory animals have shown that the acute and chronic toxicity, including the teratogenicity and carcinogenicity, of heavy metals is mediated by physicochemical factors. A similar dependence of the mutagenicity and clastogenicity of heavy metals by the physicochemical characteristics unique to specific body fluids and tissues may explain the association of specific heavy metal-induced tumors with specific tissues. There is an apparent need to develop genotoxicity tests that incorporate into their procedures the mediating influence of physicochemical factors (pH, for example), as the use of only standardized procedures may hinder the detection of heavy metal, as well as of organic, genotoxins whose mutagenicity or clastogenicity is altered by conditions other than those used in the standardized assay, thereby producing false negative results.

Animals↗
PubMed1983

Synergism between nickel and copper in their toxicity to microbes: mediation by pH.

The toxicity of a combination of nickel (Ni) and copper (Cu) toward growth of heterotrophic microorganisms was greater than the sum of the toxicity of each metal individually. This synergism between Ni and Cu was potentiated at acidic pH levels, with the potentiation of the toxicity being, for some organisms, an effect of the acidic pH on the toxicity of the Ni, rather than of the Cu, component. For others, however, the potentiation was an effect of acidic pH on both the Ni and Cu components. The potentiation of the Ni-Cu synergistic interaction at acidic pH levels has relevance to the deposition of acid precipitation into environments contaminated with these metals. Furthermore, the occurrence of such synergistic interactions and their mediation by pH should be considered in the methodologies used to establish criteria for tolerable levels of metals in the environment.

Bacteria↗
PubMed1983

Further studies on environmental factors that modify the toxicity of nickel to microbes.

The toxicity of nickel (Ni) to mycelial growth of filamentous fungi and to replication of eubacteria, an actinomycete, and yeasts was influenced by various environmental abiotic factors. Sulfide and phosphate reduced the toxicity of Ni by the formation of insoluble salts. The clay minerals, montmorillonite and, to a much lesser extent, kaolinite, and the hydrous oxides of aluminum or manganese reduced the toxicity, presumably by the adsorption of cationic Ni to their net negatively charged surfaces. Amino acids, such as aspartic acid, complex organics, such as tryptone, casamino acids, and yeast extract, and chelating agents, such as citrate, 2,6-pyridine dicarboxylic acid, nitrilotriacetic acid, and ethylenediaminetetraacetic acid, significantly reduced the toxicity of Ni, presumably as the result of decreased attraction between the net negatively charged cell surfaces and the complexed Ni. The toxicity of Ni varied in different commercial media, with greater toxicities occurring in nutrient broth and MR-VP medium and lower toxicities occurring in lauryl tryptone, Elliker, microinoculum, and tryptic soy broths. Nickel had a lower toxicity in solid media gelled with Gelrite than with Bacto-agar.

Aspartic Acid↗
PubMed1983

Developing standards for environmental toxicants: the need to consider abiotic environmental factors and microbe-mediated ecologic processes.

This article suggests and discusses two novel aspects for the formulation of standards for environmental toxicants. First, uniform national standards for each pollutant will be underprotective for some ecosystems and overprotective for others, inasmuch as the toxicity of a pollutant to the indigenous biota is dependent on the physicochemical properties of the recipient environment. As the number of chemicals that need regulation is immense and as microbes appear to respond similarly to pollutant-abiotic factor interactions as do plants and animals, it is suggested that microbial assays be used initially to identify those abiotic factors that most influence the toxicity of specific pollutants. Thereafter, additional studies using plants and animals can focus on these pollutant-abiotic factor interactions, and more meaningful standards can then be formulated more rapidly and inexpensively. Second, it is suggested that the response to pollutants of microbe-mediated ecologic processes be used to quantitate the sensitivity of different ecosystems to various toxicants. Such a quantification, expressed in terms of an "ecological dose 50%" (EcD50), could be easily incorporated into the methodologies currently used to set water quality criteria and would also be applicable to setting criteria for terrestrial ecosystems.

Animals↗
PubMed1982

Nickel toxicity to fungi: influence of environmental factors.

The toxicity of nickel (Ni) to the mycelial growth rates of filamentous fungi was influenced by environmental abiotic factors. Increasing the pH from acidic to alkaline levels completely eliminated the toxicity of Ni to Achyla sp. and Saprolegnia sp. Magnesium or zinc, but not potassium, sodium, calcium, or ferric, ions reduced the toxicity of Ni to Achyla sp. An antagonistic interaction between a combination of Ni + Pb was noted toward growth of Achyla sp. and Saprolegnia sp.; the interactions between combinations of Ni + Cd or Ni + Hg were less well defined. Chlorophyll, at 1%, reduced the toxicity of Ni toward Saprolegnia sp. and Cunninghamella blakesleeana, and increasing the chlorophyll concentration from 0.2 to 1% progressively reduced the toxicity of Ni to Aspergillus clavatus. The addition of 1% humic acid reduced the toxicity of Ni to Saprolegnia sp. and C. blakesleeana, and increasing the humic acid concentration from 0.2 to 1% progressively reduced the toxicity of Ni toward Aspergillus flavus. A. flavus was more resistant to Ni at 33 than at 23 degrees C.

Cadmium↗