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Biomedical subjects

A J Ryan

Publications and source records attributed to A J Ryan.

At least 91 records · Page 5Linked to original sources
PubMed1983

Metabolism of 7-methylbenz[c]acridine: comparison of rat liver and lung microsomal preparations and identification of some minor metabolites.

The metabolism of the carcinogenic polycyclic aza-aromatic compound, 7-methylbenz[c]acridine, has been studied in lung and liver microsomal preparations obtained from control and induced rats. Minor metabolites not previously identified included, trans-10,11-dihydro-10,11-dihydroxy-7-methylbenz[c]acridine, trans-1,2-dihydro-1,2-dihydroxy-7-methylbenz[c]acridine, 7-methylbenz[c]acridine-5,6-oxide and 7-hydroxymethylbenz[c]acridine-5,6-oxide. Metabolite profiles from liver microsomes showed 7-hydroxymethylbenz[c]acridine, trans-8,9-diydro-8,9-dihydroxy-7-methylbenz[c]acridine, 7-methylbenz[c]acridine-5,6-oxide and phenols to be major products. Metabolite distributions obtained with lung microsomes were very similar although activities were much lower than those of liver microsomes prepared from the same animals.

Acridines↗
PubMed1983

The interaction of arylalkybenzimidazoles and related compounds with microsomal oxidation.

A series of 2-arylalkyl- and 2-(4'-alkyl)phenoxymethylbenzimidazoles was synthesized and evaluated as inhibitors of mixed-function oxidase activity in phenobarbitone- and beta-naphthoflavone-induced rat liver microsomes. Higher homologues of the 2-arylalkyl series were more potent inhibitors than lower homologues against all mono-oxygenase activities except aniline p-hydroxylation. Smaller 2-substituents were associated with relatively low-affinity reverse type I spectral binding behaviour, whereas larger substituents were associated with type I binding of high affinity.

Aminopyrine N-Demethylase↗
PubMed1982

Rat liver microsomal metabolites of 7-methylbenz[c]acridine.

The metabolism of the weak carcinogen 7-methylbenz[c]acridine (7MBAC) was examined in rat liver microsomes from 3-methylcholanthrene(MC)-induced animals by the use of mixed 14C- and 2H-labelled substrate. The three metabolites identified by spectroscopic and chromatographic examination were 7-OHMBAC and two dihydrodiols. The dihydrodiols were assigned structures consisted with attack on the 8,9- and 5,6- or K-region of the aromatic system.

Acridines↗
PubMed1982

Thin-layer chromatographic and high-performance liquid chromatographic separation of metabolites of the weak carcinogen, 7-methylbenz[c]acridine.

The metabolism of [14C]7-methylbenz[c]acridine, a weakly carcinogenic polycyclic aza aromatic hydrocarbon, was studied in rates in vivo, and in rat hepatocytes and hepatic microsomes. Evidence for oxidation of the methyl group and excretion of 7-hydroxymethylbenz[c]acridine and benz[c]acridine-7-carboxylic acid in rat bile was obtained by thin-layer chromatography. A reversed-phase high-performance liquid chromatographic separation of metabolites was developed and chromatographic profiles of metabolites found in vivo and formed in vitro are presented. Several synthetic potential oxidation products were used to characterise the chromatographic profiles and evidence for the in vitro formation of 7-hydroxymethylbenz[c]acridine and 5,6-dihydro-5,6-dihydroxy-7-methylbenz[c]acridine was obtained.

Acridines↗
PubMed1982

Inhibitors of hepatic mixed-function oxidases. 4. Effects of benzimidazole and related compounds on aryl hydrocarbon hydroxylase activity from phenobarbitone and 3-methylcholanthrene induced rats.

A series of 2-n-alkylbenzimidazoles inhibited cytochrome P-450 dependent aryl hydrocarbon hydroxylase (AHH) and aminopyrine N-demethylase (APDM) activities in phenobarbitone (PB) induced rat liver microsomes. 2-Un-decylbenzimidazole was the most potent compound in the series, having I50 values of 1.8 X 10(-5) and 1.5 X 10(-5) M against AHH and APDM activities, respectively. Inhibitory activity increased with increasing carbon chain length of the 2-substituent. Regression analysis showed that there was an apparent relationship between inhibitory activity and hydrophobicity (expressed as the octanol/water partition coefficient) for the inhibition of both AHH and APDM activities in PB-induced rat liver microsomes. In contrast, these compounds showed little or no inhibitory activity toward cytochrome P-448 dependent AHH activity in hepatic microsomes from 3-methylcholanthrene (3-MC) treated rats. Two 5,6-dimethylbenzimidazoles showed slight inhibitory activity and naphtho[2,3:4',5']imidazole was only threefold less active toward 3-MC-induced (I50 = 2.6 X 10(-4) M) than PB-induced (I50 = 8.4 X 10(-5) AHH activity. These results suggest that for nitrogen heterocycles there may be a relationship of increasing polycyclic size and increasing inhibitory activity toward AHH activity in 3-MC induced rat liver microsomes.

Aminopyrine N-Demethylase↗
PubMed1982

Inhibition of rat hepatic microsomal aminopyrine N-demethylase activity by benzimidazole derivatives. Quantitative structure-activity relationships.

Eight-two benzimidazole derivatives have been prepared and tested for the ability to inhibit cytochrome P-450 mediated enzyme activity (aminopyrine N-demethylase) from phenobarbitone-induced rat hepatic microsomes. Using physicochemical parameters and multiple regression analysis, we derived a quantitative structure-activity relationship (QSAR) that describes up to 87% of the data variance in terms of hydrophobic and electronic effects and the molar refractivity of the substituent in the 2-position of the benzimidazole ring.

Aminopyrine N-Demethylase↗
PubMed1982

Standards for physician training in sports medicine.

Modern interest in sports medicine dates to the founding of the International Federation of Sports Medicine in 1928. Formal training in this field has been offered in a number of European countries for many years, but only for one five-year period in the United States at one University. Medical schools in this country may offer short elective periods, but there is no residency training program and only a few fellowships available to the orthopedic surgeon. Physicians seeking postgraduate training must seek out short conferences and read the growing volume of literature. Sports medicine clinics and centers, however, have increased rapidly in number. A group of 80 physicians organized themselves to develop the basis for a curriculum in sports medicine which could be applied to both undergraduate and graduate training. It is divided into basic sciences, organ systems, clinical systems, and miscellaneous topics, and when completed, the outline will be presented to interested medical bodies for their use.

Curriculum↗
PubMed1981

Anabolic steroids are fool's gold.

Since increases in muscle strength are proportional to increases in the cross-sectional diameter of the muscles being trained, the body must convert greater than normal amounts of amino acids available to it to increase size in athletes in training. When androgens became available in the 1930's they were used primarily to restore positive nitrogen balance in victims of starvation. Anabolic steroids, which were developed to avoid unwanted effects of androgens, were first given to weight lifters, but football players and weight throwers were soon using them. From 1965 to 1977, 25 clinical studies were published dealing with the administration of an anabolic-androgenic steroid to adult human males for evaluating changes in strength and, in 10 of these studies, in maximum oxygen consumption. In 12 of these studies, improvements were claimed from the use of these steroids; in the other 13 no improvements were observed. Other studies have shown that in healthy adult males these steroids reduce testosterone and gonadotrophin output, which reduces spermatogenesis. Alterations of normal liver function have been found in up to 80% of persons treated with C17-alkylated testosterone derivatives. Peliosis hepatitis, with liver failure and death, and fatal liver cancer have also been reported in adults so treated. Reliable methods for detecting anabolic steroids in the urine are now used in certain international competitions. Testing, announced bans, and disqualifications have not been effective in controlling the use of the drugs. The best hope for doing so lies in continuing education of athletes and their supervisors.

Anabolic Agents↗
PubMed1980

Physical fitness for physicians.

The typical workload of a physician probably is not sufficient to produce and maintain a state of physical fitness. A majority of physicians seem to be involved in recreational exercise. However, the necessary data are not available regarding the frequency, duration, and intensity of their exercise--let alone on maximum heart rates and oxygen consumption in exercise--to permit determining their levels of physical fitness. Among the many factors contributing to an overall state of physical fitness, cardiovascular and pulmonary fitness (ie, endurance) appears to be most important to the physician, whose work, with rare exceptions, requires endurance but not unusual strength. Activities most suitable to development of this type of fitness include fast walking, running, cycling, swimming, and circuit training. The exercise prescription should be expressed in terms of the heart rate to be reached, and the frequency, duration, and intensity of the activity to be performed.

Alcohol Drinking↗