PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Pyrolysis”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 775 records · Page 43Linked to original sources
PubMed2004

Estimation of the molecular mass range of the tar from pyrolysis of casein by gas chromatography-mass spectrometry, probe mass spectrometry and size exclusion chromatography with 1-methyl-2-pyrrolidinone as eluent.

Casein has been pyrolysed to obtain a biochar (28.3% yield), with mostly meso- and macro-pore structure, and a liquid tar product of high yield (37.5%) with the balance as gas (20.9%) and water (13.3%). The elemental composition of the casein tar was: C 66.7%, H 8.3%, N 12.1% and O 12.9% (by difference). The tar sample has been characterised by mass spectrometry, gas chromatography (GC)/MS and heated-probe MS, to give molecular mass distributions for comparison with molecular mass ranges indicated by analytical-scale size-exclusion chromatography (SEC). The tar appeared to be completely soluble in 1-methyl-2-pyrrolidinone (NMP), the solvent used for SEC. It appeared to consist mostly of lower molecular mass fractions with elution times at 18-26 min. GC/MS analysis showed the presence of both aliphatic and aromatic nitrogen-containing components. Neither GC/MS nor heated-probe MS were able to detect more than about half the tar components.

Animals↗
PubMed1989

[Present and future of carcinogenic tryptophan pyrolysis products in the environment].

Food has been considered an important factor for the genesis of cancer in man, as important as cigarette smoking. Diet influences the incidence of human cancer in many ways, directly and indirectly. Various kinds of carcinogens such as polynuclear aromatic hydrocarbons, N-nitro compounds and mycotoxins have been reported to be present in various foods. During the last decade, a new series of heterocyclic amines has been isolated as potent mutagens and later shown to be potent carcinogens in animals. Among them, carcinogenic tryptophan pyrolysates have been investigated from various points of view and useful pieces of information about them have been collected. Now, it is a matter of urgency to evaluate the effects of these carcinogens on humans. From this aspect, this review describes the information about carcinogenic tryptophan pyrolysates which has been collected and also future problems, especially those the hygienist will have to solve.

Carbolines↗
PubMed1986

Metabolic aspects of pyrolysis mutagens in food.

The first step in metabolic activation of mutagenic and carcinogenic heterocyclic amines has been elucidated to be N-hydroxylation by cytochrome P-448. N-Hydroxyamino compounds are further activated to form N-O-acyl derivatives that readily react with DNA. The adducts between the metabolites of Trp-P-2 and Glu-P-1 and DNA were shown to have a C8-guanylamino structure. In the case of Glu-P-1, modification of guanine in GC clusters occurred preferentially. Glutathione transferases and myeloperoxidase were shown to inactivate some heterocyclic amines or their active metabolites. Hemin and fatty acids bind to and inactivate them. Fibers and other factors from vegetables also work to inactivate heterocyclic amines. Nitrite at low pH also degraded some heterocyclic amines, but those with an imidazole moiety were resistant. Glu-P-1 induced intestinal tumors in a high incidence when fed orally to rats. When 14C-Glu-P-1 was administered by gavage into rats about 50% and 35% were excreted into feces and urine, respectively, within 24 hr. When the bile was collected, around 60% of radioactivity was excreted into it within 24 hr. In the bile, N-acetyl-Glu-P-1 was identified as one of the metabolites of Glu-P-1. It showed a mutagenic activity of about one fourth that of Glu-P-1 with S9 mix. Some radioactivity was also detected in the blood. At 24 hr after administration, most of the radioactivity was found to be bound to erythrocyte beta-globins and serum proteins including albumin.

Animals↗
PubMed1995

Abuse of smoking methamphetamine mixed with tobacco. III. Urinary metabolites of N-cyanomethylmethamphetamine, a pyrolysis product formed by smoking methamphetamine in tobacco, and species difference in its metabolism between rat and mouse.

1. N-cyanomethylmethamphetamine (CMMA) or methamphetamine (MA) was given intraperitoneally to rat and mouse (1, 3, 10 mg/kg). The basic urinary metabolites of CMMA were determined by mass spectrometry (MS) and compared with those of MA. 2. N-formylmethamphetamine (FMA), a specific metabolite of CMMA, was found in both rat and mouse urine. However, the dose percentage of FMA excreted in mouse urine was less than one-quarter of that in rat urine. 3. No CMMA was detected in rat or mouse urine collected within 72 h after dosing. All other basic metabolites of CMMA except FMA, i.e. MA, amphetamine (AP), p-hydroxymethamphetamine (OHMA) and p-hydroxyamphetamine (OHAP), were the same as those of MA in both species. 4. The excretion pattern of the urinary metabolites of CMMA was similar to that of MA except FMA in both species, though the amount of each metabolite of MA administration was larger than that of CMMA administration. However, in urinary excretion of FMA and hydroxylated metabolites, definite species differences were observed between rat and mouse. 5. A trace amount of FMA was identified in the urine of an abuser who had smoked MA with tobacco.

Amphetamines↗