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Biomedical subjects

J D Adams

Publications and source records attributed to J D Adams.

At least 127 records · Page 7Linked to original sources
PubMed1983

N-nitrosamines in laboratory animal feed and bedding.

Volatile nitrosamine concentrations in laboratory animal feeds and bedding were determined by gas chromatography with a thermal energy analyzer. N-nitrosodimethylamine was detected in all samples of NIH-07 meal (range of 1.2 to 65.9 parts per billion) and 62% of NIH-07 pellet samples (0.6 to 35.2 parts per billion). It was also detected in 66% of closed formula meal (1.9 to 45.1 parts per billion) and 83% of closed formula pellets (0.2 to 21.3 parts per billion). Low concentrations were found in samples of hardwood chip and corncob bedding. Less frequently found in feed samples were N-nitrosodipropylamine, N-nitrosoethylmethylamine, and N-nitrosopyrrolidine. The latter was not detected in the closed formula diets. Traces of three nitrosamines (N-nitrosodimethylamine, N-nitrosodipropylamine, and N-nitrosomorpholine) were found in a single sample of AIN-76 mineral mix. These latter two nitrosamines and N-nitrosoethylmethylamine have not been reported previously in laboratory animal feeds.

Animal Feed↗
PubMed1982

Derivatization of chiral amines with (S,S)-N-trifluoroacetylproline anhydride for GC estimation of enantiomeric composition.

The reaction characteristics of (S,S)-N-trifluoroacetylproline anhydride were examined in an attempt to develop a quantitative GC assay of the enantiomers of the sterically hindered, chiral amine ketamine. With the aid of the individual enantiomers of ketamine and the corresponding synthetic N-trifluoroacetylprolyl amides, it was found that the derivatization reaction proceeds stereoselectively, in poor yield, and with some degree of racemization of the acylating reagent. The results indicate that care must be exercised when prolyl derivatizing reagents are chosen for assaying chiral amines.

Amines↗
PubMed1982

Assessment of the potential agonistic and antagonistic properties of ketamine at opiate receptors in the guinea-pig ileum.

The anesthetic agent ketamine was studied for its ability to interact with opiate receptors in the longitudinal smooth muscle-myenteric plexus preparation of the guinea-pig ileum. The drug was found to possess agonistic, but not antagonistic, activity on opiate receptors. Naloxone antagonized the effect of ketamine although to a lesser degree than the antagonism exhibited toward morphine. In addition to the opiate action, ketamine also produced a depression of the contractile responses of the ileal smooth muscle to acetylcholine and histamine. The concentrations of ketamine that produced this non-specific depression were generally higher than those needed to demonstrate the opiate effect. However, some overlap in the concentration ranges for the two actions were observed. Although the nature of the opiate action of ketamine suggested that it interacts with opiate receptors or sub-types of these differently than does morphine, the non-specific action of the drug on the ileal smooth muscle precluded a definitive analysis of differences in the opiate receptor preferences of the drug.

Acetylcholine↗
PubMed1982

Cadmium and nickel in smoke of cigarettes prepared from tobacco cultured on municipal sludge-amended soil.

Cigarettes prepared from tobacco grown on municipal sludge-amended soil were smoked, and the mainstream particulates and gaseous fractions were analyzed for total cadmium and nickel content. Sludge-grown and control (soil-grown) tobaccos contained, respectively, 67.4 and 3.18 ppm of cadmium and 19.4 and 1.29 ppm of nickel. The quantities of cadmium (microgram per cigarette) found in the mainstream particulate and gaseous fractions were, respectively, 6.67 and 0.04 for the sludge-grown and 0.21 and 0.03 for the control treatments. The quantities of nickel (microgram per cigarette) found in the mainstream particulates and gaseous fractions were, respectively, 0.11 and 0.07 for the sludge-grown and 0.01 and 0.01 for the control treatments. The potential public health implications of these results and modifying factors are discussed.

Cadmium↗
PubMed1982

Tobacco specific N-nitrosamines: occurrence and bioassays.

A new GC-TEA method for the analysis of tobacco-specific N-nitrosamines (TSNA) has been developed. Four TSNA have thus far been identified; these are N'-nitrosonornicotine (NNN), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), N'-nitrosoanatabine (NAT) and N'-nitrosoanabasine (NAB). The method is currently being applied to the development of cigarette filter-tips which will selectively remove these carcinogens from cigarette smoke. Since recent epidemiological studies have established a correlation between snuff dipping and oral cancer, we have analysed leading snuff brands for TSNA. Snuff products from Sweden, Denmark, Bavaria and the USA contained 5-106 mg/kg of the TSNA and the saliva of snuff dippers had TSNA levels of 20-890 micrograms/kg. NNN, NNK and NAB induce benign and malignant tumours of the respiratory tract of mice and rats. We have shown that NNN and NNK induce tumours in the upper respiratory tract of hamsters and that NNK is the most active carcinogen of the TSNA, also inducing adenoma and adenocarcinoma in the hamster lung. The reported chemical analyses and bioassay results support the epidemiological findings on the causal association of tobacco use and cancer in man.

Adult↗
PubMed1981

Studies on the biotransformation of ketamine. 1-Identification of metabolites produced in vitro from rat liver microsomal preparations.

The in vitro metabolic fate of the anesthetic agent ketamine [(+)2-o-chlorophenyl-2-methylaminocyclohexanone] has been evaluated using microsomal preparations from rat liver. With the aid of a rapid, nonselective metabolite extraction procedure and sample analysis by combined glass capillary gas chromatography low (and high) resolution mass spectrometry, eight metabolites of the drug were identified, six of which have not been reported previously. The novel metabolites were products of alicyclic ring hydroxylation of ketamine and of N-desmethylketamine (norketamine). Semi-quantitative analysis of metabolites produced during microsomal incubation was achieved using glass capillary gas chromatography. The results from this study indicate that 5,6-dehydronorketamine, previously considered to be a major biotransformation product of ketamine in mammalian systems, is almost certainly a methodological artefact.

Animals↗
PubMed1981

Carcinogenic tobacco-specific N-nitrosamines in snuff and in the saliva of snuff dippers.

Human data indicate an increased risk for cancer of the oral cavity for snuff dippers. Popular snuff products from the United States, Germany, Sweden, and Denmark were analyzed for tobacco-specific N-nitrosamines (TSNA). These compounds are formed during tobacco processing from nicotine, nornicotine, and anatabine and represent the only known carcinogens in snuff. N'-Nitrosonornicotine, a moderately active carcinogen, ranged in dry snuff from 3.5 to 77 ppm; 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, a relatively strong carcinogen, ranged from 0.6 to 7.0 ppm; and N'-nitrosoanatabine, thus far not bioassayed, ranged from 0.8 to 44 ppm. The concentrations of TSNA in a given snuff product can vary widely, and aging in the open air can lead to an increase in TSNA. Analysis of the saliva of snuff dippers revealed that these nitrosamines are extracted from the tobacco plug during snuff dipping and that their concentrations in saliva can vary widely between users. Efforts should be made to reduce the TSNA in snuff by modifications of the production process and by wrapping individual snuff portions in airtight packets.

Adult↗
PubMed1980

Chemical studies on tobacco smoke LXVIII. Analysis of volatile and tobacco-specific nitrosamines in tobacco products.

The yields of volatile N-nitrosamines in cigarette smoke are primarily dependent upon the nitrate content of the tobacco and, to some extent, on the protein content. Cellulose acetate tips, such as those found on most commercial filter cigarettes, selectively remove at least 70% of the volatile N-nitrosamines, independently of the pH of the weakly acidic or weakly alkaline smoke. So far, three tobacco-specific N-nitrosamines have been detected in tobacco and tobacco smoke. During tobacco processing and smoking, N'-nitrosonornicotine is formed by nitrosation of nicotine and, to a minor degree, by nitrosation of nornicotine, whereas 4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone originates from oxidative nitrosation of nicotine. N'-Nitrosoanatabine is formed by nitrosation of the second most abundant tobacco alkaloid, anatabine. The tobacco-specific N-nitrosamines in the smoke arise partly from the tobacco by transfer and partly by nitrosation of the alkaloids during smoking (pyrosynthesis). Preliminary results indicate that cellulose acetate filter tips may selectively remove considerable amounts of the nonvolatile nitrosamines from the smoke.

Chromatography, High Pressure Liquid↗
PubMed1980

Relation of breathing oxygen-argon gas mixtures to altitude decompression sickness.

A 95% oxygen-5% argon breathing mixture produced by a molecular sieve generator was shown to be similar to a 95% O2-5% N2 mixture for breathing during 1-h exposures at 7,620 m (25,000 ft) or 10,972 m (35,000 ft), as determined by the detection of proportionate numbers of intravascular bubbles in the pulmonary artery of dogs. Comparable results were obtained with 95% O2-5% He or 100% O2. The partial pressures of a 5% mixture at 7,620 and 10,972 m were 14.1 and 8.6 torr, respectively, and were apparently low enough so that the nonmetabolizable gases did not result in differences in the incidence of intravascular bubble formation or decompression sickness. Argon at the 10% level showed a nonsignificant trend to produce more bubbles. Individual susceptibility or resistance to form bubbles was observed with the different gases. Denitrogenation with either 5 or 10% mixtures of the inert gases was quite effective, as shown by a reduction in the number of intravascular bubbles detected.

Aerospace Medicine↗
PubMed1979

Molecular sieve oxygen generating system: the argon question--a brief review.

The molecular sieve oxygen generating system (MSOG) is currently being considered as a replacement for liquid and gaseous stores on aircraft for the supply of aviator's breathing oxygen. Incorporation of onboard oxygen generation in aircraft not only increases system safety but also minimizes logistic requirements. However, a unique characteristic of the MSOG is that it concentrates not only oxygen but also argon in the process of removing nitrogen from engine bleed air. Maximum concentrations produced by present systems are in the order of 95% oxygen and 5% argon. These results have precipitated numerous questions relating to the physiological effects of argon in the product breathing gas. This report reviews the current literature concerning argon as a minor constituent (less than 10%) in gas breathing systems and recommends studies prior to human compatibility testing of the molecule sieve oxygen generating systems.

Aerospace Medicine↗