Search PubMed⌕ Search

Biomedical subjects

F T Hatch

Publications and source records attributed to F T Hatch.

At least 37 records · Page 2Linked to original sources
PubMed1986

A current genotoxicity database for heterocyclic thermic food mutagens. I. Genetically relevant endpoints.

Cooking, heat processing, or pyrolysis of protein-rich foods induce the formation of a series of structurally related heterocyclic aromatic bases that have been found to be mutagens. The primary genetic assay utilized to detect and isolate these mutagens has been the his reversion assay in Salmonella typhimurium. The classification and nomenclature of these chemicals is revised to reflect recent advances. The findings of short-term tests for genetic injury that have been applied to these agents are presented in a systematic way. Cell-free, bacterial, mammalian cell culture, and in vivo systems are included. Major results, the mutagens tested, and key references are presented in tabular form, with text commentary. Integrated conclusions on the state of current knowledge of the genetic toxicity of thermic food mutagens are presented. Areas in need of further research are defined. Finally, an outline is presented of a suggested path leading to the determination whether normal methods of food preparation and processing constitute a human health hazard.

Animals↗
PubMed1985

Effects of temperature, patty thickness and fat content on the production of mutagens in fried ground beef.

The high-pressure liquid chromatography (HPLC) profiles of mutagenic components were compared for extracts of ground beef patties fried at 200, 250 and 300 degrees C for 6 min/side. The HPLC profiles of the mutagenic samples were similar, although total mutagenic activity in Salmonella typhimurium TA1538 was roughly four times as high after the 300 degrees C than after the 200 degrees C frying. Six mutagenic peaks were analysed quantitatively at different temperatures and meat thicknesses. Two major components, 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline and 2-aminotrimethylimidazo[4,5-f]quinoxaline, and a minor component, 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), were all present at the three different temperatures. Thus, in general, cooking temperature seems to have a major effect on the quantities of mutagens produced but not on their HPLC profiles. The thickness of the meat patty did not affect the total yield of mutagens except at longer cooking times (8-10 min/side) and, in general, neither did it affect the HPLC profiles of the mutagenic components. Total mutagenic activity increased with increasing cooking times. Increasing the fat content lowered the total mutagenicity, with 150,000 revertants/kg of fresh beef at 30% fat compared with 230,000 revertants/kg at 15%, but had little effect on the mutagenicity due to IQ.

Animals↗
PubMed1984

Mutagens in cooked foods--metabolism and genetic toxicity.

Recently developed in our laboratories is an efficient extraction procedure incorporating XAD resin adsorption which yields from 200 degrees C grilled ground beef an extract containing 230 Salmonella TA1538 revertants per g fresh weight of original ground beef. These mutagenic components are specific for frameshift-sensitive Salmonella strains and have an absolute requirement for metabolic activation. S9 activation by cytochrome P-448 inducers, Aroclor 1254 (PCB), 3-methylcholanthrene (3-MC) and B-naphthoflavone (BNF), resulted in the largest mutagenic response. Phenobarbital induction gave 20% of the PCB response and Pregnenolone-16a-carbonitrile and corn oil were inactive. Human liver microsomes and BNF-induced rodent intestinal S9 were also active metabolizing fractions. Normal-phase HPLC separation of methanol-extractable metabolites generated from reaction of 2-amino-3-methylimidazo [4,5-f]quinoline (IQ), a mutagenic component of broiled food, rat liver microsomes and cofactors resulted in one direct-acting mutagenic peak and a second more polar peak still requiring metabolic activation. Two potent thermally-produced bacterial mutagens, Trp-P-2 and IQ, were examined in mammalian cells. In excision repair-deficient CHO cells, Trp-P-2 exposure caused cytotoxicity, mutagenicity (thioguanine and azaadenine resistances), sister chromatid exchange, and chromosomal aberrations at concentrations more than 30-fold lower than those for IQ. In normal repair-proficient CHO cells Trp-P-2 was one-half as active and IQ was inactive. Relative to Trp-P-2, IQ is much more potent in the Salmonella bacterial system than in mammalian CHO cells.

Animals↗
PubMed1984

Isolation and characterization of new mutagens from fried ground beef.

Frying of ground beef at 250 degrees C results in the formation of a series of mutagenic heterocyclic amines, possibly as many as 10 distinct compounds. In this study, the mutagens are separated by aqueous/acid extraction from the beef, XAD adsorption, acid/neutral/base-liquid/liquid extraction, preparative reverse phase h.p.l.c., normal phase h.p.l.c., and analytical reverse phase h.p.l.c. Identification is by low and high resolution mass spectrometry, u.v. absorption spectroscopy and nitrite sensitivity assays. More than 30% of the mutagenic material is identified as 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx). The previously described beef mutagen, 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) contributes less than 12% of the total mutagenicity at high temperatures (300 degrees C) and less than 4% at lower temperatures. In addition to MeIQx major mutagens are seen with molecular ions at m/z 227 (C12H13N5), 209 (C13H11N3), and 176 (C9H12N4). Two very polar and two non-polar peaks making a relatively minor contribution to the total mutagenicity (less than 16% total) have not yet been identified. Estimates of the mass of these mutagens in the original cooked beef were made from the mass spectral analysis and the mutagenic recoveries. From one kilogram of cooked ground beef, 1.0 micrograms MeIQx, 0.02 micrograms of IQ, and up to 1.5 micrograms of additional mutagens are formed.

Hot Temperature↗
PubMed1982

Mutagens from the cooking of food. II. Survey by Ames/Salmonella test of mutagen formation in the major protein-rich foods of the American diet.

The formation of mutagens in the major cooked protein-rich foods in the US diet was studied in the Ames Salmonella typhimurium test. The nine protein-rich foods most commonly eaten in the USA--ground beef, beef steak, eggs, pork chops, fried chicken, pot-roasted beef, ham, roast beef and bacon--were examined for their mutagenicity towards S. typhimurium TA1538 after normal 'household' cooking (deep frying, griddle/pan frying, baking/roasting, broiling, stewing, braising or boiling of 100-475 degrees C). Well-done fried ground beef, beef steak, ham pork chops and bacon showed significant mutagen formation. For chicken and beef steak high-temperature broiling produced the most mutagenicity, followed by baking/roasting and frying. Stewing, braising and deep frying produced little mutagen. Eggs and egg products produced mutagens only after cooking at high temperatures (the yolk to a greater extent than the white). Commercially cooked hamburgers showed a wide range of mutagenic activity. We conclude that mutagen formation following cooking of protein-containing foods is a complex function of food type, cooking time and cooking temperature. It seems clear that all the major protein-rich foods if cooked to a well-done state on the griddle (eggs only at temperatures above 225 degrees C) or by broiling will contain mutagens detectable by the Ames/Salmonella assay. This survey is a step towards determining whether any human health hazard results from cooking protein-rich foods. Further testing in both short- and long-term genotoxicity bioassays and carcinogenesis assays are needed before any human risk extrapolations can be made.

Animals↗
PubMed1982

Mutagens from the cooking of food. III. Survey by Ames/Salmonella test of mutagen formation in secondary sources of cooked dietary protein.

A survey of mutagen formation during the cooking of a variety of protein-rich foods that are minor sources of protein intake in the American diet is reported (see Bjeldanes, Morris, Felton et al. (1982) for survey of major protein foods). Milk, cheese, tofu and organ meats showed negligible mutagen formation except following high-temperature cooking for long periods of time. Even under the most extreme conditions, tofu, cheese and milk exhibited fewer than 500 Ames/Salmonella typhimurium revertants/100 g equivalents (wet weight of uncooked food), and organ meats only double that amount. Beans showed low mutagen formation after boiling and boiling followed by frying (with and without oil). Only boiling of beans followed by baking for 1 hr gave appreciable mutagenicity (3650 revertants/100g equivalents). Seafood samples gave a variety of results: red snapper, salmon, trout, halibut and rock cod all gave more than 1000 revertants/100 g wet weight equivalents when pan-fried or griddle-fried for about 6 min/side. Baked or poached rock and deep-fried shrimp showed no significant mutagen formation. Broiled lamb chops showed mutagen formation similar to that in red meats tested in the preceding paper: 16,000 revertants/100 g equivalents. These findings show that as measured by bioassay in S. typhimurium, most of the foods that are minor sources of protein in the American diet are also minor sources of cooking-induced mutagens.

Animals↗
PubMed1981

Mutagens from the cooking of food. I. Improved extraction and characterization of mutagenic fractions from cooked ground beef.

Ground beef was fried at 200 degrees C (392 degrees F) to a well-done, non-charred state, and the extracted organic base fraction was found to be highly mutagenic in Salmonella strain TA1538 (6300 revertants/100 g equivalent, gE, fresh weight). The neutral and acidic extracts showed no mutagenic activity in any of the 5 standard strains of Salmonella. A new procedure based upon extraction and protein precipitation with acetone is described, which is simpler and more efficient than previously described methods. The organic base fraction was mutagenic only in Salmonella strains TA1537, TA1538, and TA98, all sensitive to frameshift mutations. Strains sensitive to base-substitution mutations showed no activity. Metabolic activation was an absolute requirement for mutagenesis; however cell toxicity was decreased by the presence of S9 activation mixture. After normal cooking, more than 20 times as much mutagenic material remained in the meat as was recovered in the pan grease and vapors. The results confirm that mutagens are formed under conventional frying conditions, and show that mutagen can be isolated by an improved extraction method.

Animals↗
PubMed1981

Priorities assessment for studies of mutagen production in cooked foods.

As a component of a project investigating the formation of mutagens in foods under normal cooking processes, dietary practices in the U.S. were assessed for the purpose of setting priorities for food items to be tested for possible mutagen information when cooked. High-protein foods are of primary concern because cooking of these foods results in greater mutagenic activity compared to cooking of other foods. Highest priorities were given to foods on the basis of the following criteria: (a) food items high in protein, (b) food items consumed in large amounts, and (c) food items normally cooked. Some inconsistencies in the results of two national food consumption surveys were discussed, as were the problems inherent in cooking method terminology. Emphasis was given to the need for further research in cooking practices of the U.S. population.

Cooking↗
PubMed1979

Separation of satellite DNA chromatin and main band DNA chromatin from mouse brain.

Using restriction endonucleases which preferentially digest mouse main band DNA and leave satellite DNA intact, we have isolated highly purified chromatin fractions containing only mouse satellite or main band DNA. Following the digestion of mouse brain nuclei with EndoR Alu I, main band DNA chromatin is selectively extracted with 10mM Tris, 10mM EDTA. Satellite DNA chromatin is subsequently extracted from the nuclear pellet with Tris-3M urea and further purified on sucrose gradients. Chromatin extracted from digested nuclei with Tris-EDTA contains only main band DNA and has a molecular weight lower than 2 x 10(6). Chromatin fractions obtained from the lower regions of sucrose gradients of the Tris-Urea extracts contain 40--95% satellite DNA and have a molecular weight of 6 to 8 x 10(6). Both the satellite DNA and main band DNA chromatins contain all five histones and have a protein to DNA ratio of 1.3 to 1.

Animals↗
PubMed1977

Similarity of satilite DNA properties in the order Rodentia.

We have characterized satellite DNAs from 9 species of kangaroo rat (Dipodomys) and have shown that the HS-alpha and HS-beta satellites, where present, are nearly identical in all species as to melting transition midpoint (Tm), and density in neutral CsCl, alkaline CsCl, and Cs(2)SO(4)-Ag(+) gradients. However, the MS satellites exist in two internally similar classes. The satellite DNAs from three other rodents were characterized (densities listed are in neutral CsCl). The pocket gopher, Thomomysbottae, contains Th-alpha (1.713 g/ml) and Th-beta (1.703 g/ml). The guinea pig (Caviaporcellus) contains Ca-alpha, Ca-beta and Ca-gamma at densities of 1.706 g/ml, 1.704 g/ml and 1.704 g/ml, respectively. The antelope ground squirrel (Ammospermophilusharrisi) contains Am-alpha, 1.708 g/ml, Am-beta, 1.717 g/ml, and Am-gamma, 1.707 g/ml. The physical and chemical properties of the alpha-satellites from the above four rodents representing four different families in two suborders of Rodentia were compared. They show nearly identical Tm, nucleoside composition of single strands, and single strand densities in alkaline CsCl. Similar comparisons on the second or third satellite DNAs from these rodents also indicate a close relationship to each other. Thus the high degree of similarity of satellite sequences found in such a diverse group of rodents suggests a cellular function that is subject to natural selection, and implies that these sequences have been conserved over a considerable span of evolutionary time since the divergence of these rodents about 50 million years ago.

Animals↗
PubMed1976

Satellite DNA and cytogenetic evolution. DNA quantity, satellite DNA and karyotypic variations in kangaroo rats (genus Dipodomys).

The genus Dipodomys (kangaroo rats) exhibits major interspecies variations in the proportions of highly reiterated satellite DNA sequences in the genome as well as in the chromosome number and the proportions of uni-armed and bi-armed chromosomes. For nearly all of the approximately 22 species of the genus and several subspecies, liver DNA was distributed in neutral CsCl buoyant density gradients into four fractions; principal DNA (1.698 g/ml), intermediate-density DNA (1.702 G/ML), MS satellite (1.707 g/ml) and HS (heavy satellites (1.713 g/ml). The total nuclear DNA content of diploid liver cells measured in eleven species by quantitative cytophotometry, ranged from 6.9 to 10.9 pg. These data were correlated with known features of the karotypes of individual species. The salient findings were: (1) that interspecies variations in diploid chromosome number cluster at 52-54, 60-64 and 70-72 (2) that high total nuclear DNA was associated with high chromosome number, and with relatively large amounts of satellite DNA (3) that a high ratio of HS satellites to intermediate-density DNA was generally correlated with a predominance of metacentric and submetacentric chromosomes (high fundamental number). The relationships of satellite DNA to karyotype structure reveal a new level of hierarchy in the genome that appears capable of exerting global control over environmental adaptation and the evolution of new species. This mechanism is consistent with recent hypotheses that changes in the macro-structure of the genome are more important than point mutations in facilitating the rapid phases of animal evolution.

Animals↗
PubMed1976

Single-strand nuclease action on heat-denatured spermiogenic chromatin.

The aim of this study was to compare the sensitivity of chromatin from representative cellular stages of spermiogenesis to a single-strandeded nuclease after heat denaturation. Thermal denaturation of chromatin was assayed in situ in fixed round, elongating and elongated spermatids and in testicular sperm from mice. Production of single-stranded deoxyribonucleic acid (DNA) at elevated temperatures was monitored by digesting chromatin with endonuclease specific for single-stranded DNA (S1 nuclease), staining the residual DNA with gallocyanin-chrome alum (GAC) and measuring the stain content by absorption cytophotometry. Changes in GCA staining were minimal over the temperature range of 22-90 degrees C in each cell type not exposed to nuclease. Staining of undigested cells decreased progressively with advancing cell maturity. Nuclease had no effect on the GCA content of round spermatids below 60 degrees C, but above this temperature there was a progressive decrease in GCA-stainable chromatin. Both round and elongating spermatid stages showed a significantly greater sensitivity to nuclease digestion than did more mature stages; sperm showed no effects of nuclease action below 80 degrees C. Progressive chromatin condensation and a concomitant decrease in the number of available DNA phosphate groups during spermiogenic cell maturation may be responsible for the observed decline in sensitivity to nuclease and decreased GCA staining. Thermal denaturation of round spermatids labeled with 3H-thymidine produced no change in autoradiographic mean nuclear grain counts, indicating no loss of thymidine-labeled DNA from the slides during denaturation. When round spermatids and sperm were hydrolyzed with hot tricholoroacetic acid before staining, both nuclear GCA content and autoradiograph grain count were partially reduced, indicating incomplete DNA removal. Almost complete loss of Feulgen-stainable material occurred in these cells and may be due to depurination and elimination of Feulgren-reactant aldehyde groups.

Animals↗