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Biomedical subjects

G Stotzky

Publications and source records attributed to G Stotzky.

At least 73 records · Page 4Linked to original sources
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

Protein-membrane interactions: specific vs. non-specific adsorption and binding of proteins and polyamino acids on erythroblasts transformed by Friend virus.

Friend-virus transformed erythroblasts (HFL cells) were incubated in solutions containing up to 3 different proteinaceous compounds at pH 7.2 or 5.5 at 5 degrees C. The specificity of interaction of each compound with the cell surface was determined by comparing the amounts of each compound adsorbed and bound in the presence of 2 or 3 different compounds or after prior binding of another compound to the amounts when the individual compounds alone interacted with the cells. At pH 7.2, ovalbumin and gelatin apparently interacted with cell surface components common to both proteins, as indicated by a decrease (up to 80%) in the amount of each compound adsorbed and bound in the presence, or after the binding, of the other compound. The relative amounts of each compound that interacted were different at pH 5.5 and pH 7.2. Gelatin and poly-L-lysine interacted mainly with different components at pH 7.2, whereas common components appeared to be involved at pH 5.5. Concanavalin A interacted preferentially with components that it shared with lysozyme at both pH values. In addition to variations in interactions with changes in pH and type of compound, variations occurred with changes in concentration of the compounds and with their sequence of addition to the cells. Comparative studies with horse red blood cells showed that the interactions differed markedly with cell type.

Adsorption↗
PubMed1983

Adsorption of reovirus to clay minerals: effects of cation-exchange capacity, cation saturation, and surface area.

The adsorption of reovirus to clay minerals has been reported by several investigators, but the mechanisms defining this association have been studied only minimally. The purpose of this investigation was to elucidate the mechanisms involved with this interaction. More reovirus type 3 was adsorbed, in both distilled and synthetic estuarine water, by low concentrations of montmorillonite than by comparable concentrations of kaolinite containing a mixed complement of cations on the exchange complex. Adsorption to the clays was essentially immediate and was correlated with the cation-exchange capacity of the clays, indicating that adsorption was primarily to negatively charged sites on the clays. Adsorption was greater with low concentrations of clays in estuarine water than in distilled water, as the higher ionic strength of the estuarine water reduced the electrokinetic potential of both clay and virus particles. The addition of cations (as chloride salts) to distilled water enhanced adsorption, with divalent cations being more effective than monovalent cations and 10(-2) M resulting in more adsorption than 10(-3) M. Potassium ions suppressed reovirus adsorption to montmorillonite, probably by collapsing the clay lattices and preventing the expression of the interlayer-derived cation-exchange capacity. More virus was adsorbed by montmorillonite made homoionic to various mono-, di-, and trivalent cations (except by montmorillonite homoionic to potassium) than by comparable concentrations of kaolinite homoionic to the same cations. The sequence of the amount of adsorption to homoionic montmorillonite was Al greater than Ca greater than Mg greater than Na greater than K; the sequence of adsorption to kaolinite was Na greater than Al greater than Ca greater than Mg greater than K. The constant partition-type adsorption isotherms obtained when the clay concentration was maintained constant and the virus concentration was varied indicated that a fixed proportion of the added virus population was adsorbed, regardless of the concentration of infectious particles. A heterogeneity within the reovirus population was indicated.

Adsorption↗
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↗
PubMed1983

Identification of surface antigens of endothelial cells.

A monolayer of a clone of endothelial cells derived from rat lung cells (RLE) was overlaid with 1 M urea to extract the surface proteins. Hydrolysis and SDS-gel electrophoresis of the urea extracted cell surface proteins (UCSP) yielded four peptides of 350,000, 84,000, 66,000 and 18,500 molecular weight. Of these only the 66,000 and 18,500 molecular weight peptides reacted with antibodies raised in rabbit against rat lung endothelial cells (RLE). The 18,500 mol. wt. antigenic peptide was a serum protein associated with the cell surface, whereas the 66,000 mol. wt. peptide was the surface antigen synthesized and released into the medium by the rat lung endothelial cells. On rocket immunoelectrophoresis, the 66,000 mol. wt. rat kidney fibroblast surface peptide produced only a single rocket whereas peptides of RLE produced two rockets, suggesting the presence of an additional antigenic peptide which could serve as a marker for endothelial cells.

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↗
PubMed1982

Adsorption of coliphages T1 and T7 to clay minerals.

Coliphages T1 and T7 of Escherichia coli were absorbed by kaolinite (K) and montmorillonite (M). Maximum adsorption of T7 (96%) to M was greater than that of T1 (84%), but the adsorption of both coliphages to K was the same (99%). Positively charged sites (i.e., anion exchange sites) on the clays appeared to be primarily responsible for the adsorption of T1 to K but only partially responsible for the adsorption of T1 to M; equilibrium adsorption isotherms of T1 to K and M did not show a correlation between adsorption and the cation exchange capacity of the clays, and the reduction in adsorption caused by sodium metaphosphate (a polyanion that interacts with positively charged sites on clay) was more pronounced with K than with M. The equilibrium adsorption isotherms of T7 to K and M suggested a correlation between adsorption and the cation exchange capacity of the clays. However, studies with sodium metaphosphate indicated that T7 also adsorbed to positively charged sites on the clays, especially on K. Adsorption of the coliphages to positively charged sites was greater with K than with M, probably because the ratio of positively charged sites to negatively charged sites was greater on K than on M.

Adsorption↗
PubMed1981

Dibromochloropropane (DBCP): a review.

A highly persistent, lipophilic, brominated organochlorine which is effectively used against nematodes, dibromochloropropane (DBCP) has been produced for agriculture since 1955. In 1975, production of DBCP in the United States reached 25 million lbs. However, investigations with laboratory animals, some of which were published in the early 1960s, have shown that DBCP decreases sperm mobility and spermatogenesis, disturbs the estrous cycle, reduces phagocytosis by white blood cells, and induces malignant tumors. Later studies with procaryotic and eucaryotic cells, including human sperm, have demonstrated DBCP to be mutagenic and to effect the genome adversely. In 1977 many of the employees at the Occidental Chemical plant in Lathrop, California, who had handled DBCP, were found to be either azoospermic or oligospermic. Subsequent surveys of employees handling DBCP at other chemical plants confirmed these findings. In 1977 on edible crops and in 1979 DBCP per se was detected in well waters. As a result of these studies, the Occupational Safety and Health Administration (OSHA) and the Environmental Protection Agency (EPA) in 1977 promulgated regulations restricting the use and handling of DBCP. In 1979, the EPA banned almost all agricultural uses of DBCP.

Animals↗
PubMed1980

Effect of montmorillonite and kaolinite on nitrification in soil.

A soil not naturally containing montmorillonite (M) was amended with approximately 5, 10 or 20% M or kaolinite (K), maintained in a greenhouse under periodic cultivating and alternate wetting and drying of more than two years, and then used in perfusion studies. The incorporation of M enhanced the rate of both heterotrophic degradation of glycine and subsequent autotrophic nitrification in direct relation to the amounts of M added. In soil amended with K, neither degradation nor nitrification was stimulated. The addition of M shortened the lag phase before nitrification was initiated, increased the pH of both the soil and the perfusates, and increased the rate, but not the extent, of oxidation of ammonium to nitrite and nitrate. The addition of CaCO2 or MgCO3, but not of CaSO4, also enhanced the rate of nitrification. The effects observed may have resulted from the influence of M on the pH, buffering capacity, and other soil conditions necessary for maximum activity of nitrifying microorganisms.

Bentonite↗