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Biomedical subjects

A Imamura

Publications and source records attributed to A Imamura.

At least 163 records · Page 9Linked to original sources
PubMed1981

Some quantitative evaluation of first-pass metabolism of salicylamide in rabbit and rat.

The first-pass metabolism of salicylamide (SAM) was studied in rabbits and rats paying main attention to the amounts of the glucuronide (SAMG) and sulfate (SAMS) formed. The roles of the intestine and liver for SAMG and SAMS formation during the first-pass were also examined quantitatively. Further, an equation was developed to estimate the hepatic first-pass metabolism based on the experiments of intravenous and oral administration and intestinal perfusion experiment. Significant species differences were found in these two animals. The extent of the first-pass metabolism was larger in rabbits (ca95%) than in rats (ca60%). Of the 95% first-pass metabolism in rabbits, about 30% is due to the intestine whereas the remaining 65% is due to the liver. Of the 60% in rats, about 20 and 40% are estimated to be due to the intestinal and hepatic first-pass metabolism, respectively. In rabbits SAMG and SAMS are formed together in nearly equal amounts in the liver and at the ratio 4 : 1 in the intestine. In rats, on the other hand, SAMG is exclusively formed in the intestine and SAMS in the liver. In this context, the equation described here was applied to the data of Gugler et al. (J. Pharmacol. Exp. Ther., 195, 416-423 (1975)) who carried out a study on the first-pass metabolism of SAM in dogs, and consequently, reported that glucuronidation occurs primarily in the liver whereas sulfation occurs primarily in the intestine in dogs.

Animals↗
PubMed1981

[Iron, folate and vitamin B12 in maternal blood and breast milk (author's transl)].

Maternal blood and milk iron (Fe), folate (FA), vitamin B12 (B12) and serum ferritin (Fr) were determined in four groups of lactating mothers: normal, toxemic, anemic and treated anemic during pregnancy. 1. An increasing blood Fe, Fr and a decreasing milk Fe with time in postpartum were found in each group. A high level of blood Fe, Fr was observed in the treated group. Milk Fe, however, had showed no significant difference in either group. There was no correlation between the blood and milk Fe. 2. There was no demonstrable change of blood FA, but milk FA had significantly increased in each group. Blood FA showed a low level in the toxemic group and a high level in the treated group, but no significant difference of milk FA could be found in either group. No matter how widely the level of blood FA spread, there was a little change in milk FA. 3. An increasing blood B12 and a decreasing milk B12 were found in each group. There was a tendency towards a high level of blood B12 in the treated group, but the level of milk B12 differed widely from one material to the other. There was no correlation between the blood and milk B12.

Anemia↗
PubMed1979

A molecular orbital study on the chemical reactivity and biological activity of polycyclic aromatic hydrocarbon diol-epoxides in connection with bay region theory.

Electronic structures of naphthalene-, anthracene-, phenanthrene-, and benzo-[a]pyrene-diol-epoxides were calculated by using CNDO/2 method together with the energy minimization method. By using these methods, the most stable geometry of molecules was automatically obtained. By comparing the total energy of phenanthrene-diol-epoxide with that of anthracene-diol-epoxide, the role of the bay region was studied in connection with the chemical reactivity. It is concluded that the bay region plays an important role when the diol-epoxide reacts with the component of the biological system via SNl mechanism. Moreover, benzo[a]pyrene-diol-epoxide was shown to be very reactive because fo the presence of the bay region as well as the large size of the molecule. When reaction proceeds via SN2 mechanism, the bay region is found to have little effect on the chemical reactivity of the molecules.

Anthracenes↗
PubMed1978

Lipid-lowering effect of carnitine in patients with type-IV hyperlipoproteinaemia.

Serum-lipid concentrations were determined in patients with type-IV hyperlipoproteinaemia treated with 900 mg/day oral DL-carnitine chloride. Serum-triglyceride was significantly reduced and concentrations continued to decline as carnitine administration continued. Total and esterified cholesterol concentrations did not change. Intravenous infusion of carnitine produced the same effects. The results suggest that carnitine is of value in the therapy of type-IV hyperliproteinaemia. Increased oxidation of free fatty acids in the tissues seems to account for the effects of carnitine on serum-lipid concentrations.

Administration, Oral↗
PubMed1977

Urinary excretion of carnitine in patients with hyperthyroidism and hypothyroidism: augmentation by thyroid hormone.

Urinary excretion of carnitine and serum concentrations of carnitine, triglyceride, and free fatty acids were measured in 54 hyperthyroid and 13 hypothyroid patients, and the results were compared with those of normal subjects. In hyperthyroid patients urinary excretion of carnitine was highly increased above that of the control subjects. On adequate treatment with antithyroid drug, carnitine excretion was reduced to the normal range, and serum lipids changed in parallel. In contrast, carnitine excretion was markedly reduced in hypothyroid patients. After substitution therapy with thyroid hormones the excretion increased in these patients. This change was associated with a marked reduction of serum triglyceride. There was an inverse correlation between urinary excretion of carnitine and serum triglyceride concentration. Carnitine excretion was significantly correlated with serum thyroxine concentration in hyper- and hypothyroid patients. The results suggest that thyroid hormones play an important role in carnitine metabolism, which in turn influences serum triglyceride metabolism.

Adolescent↗
PubMed1977

Urinary excretion of carnitine and serum concentrations of carnitine and lipids in patients with hypofunctional endocrine diseases: involvement of adrenocorticoid and thyroid hormones in ACTH-induced augmentation of carnitine and lipids metabolism.

The promoting effect of ACTH on carnitine and lipid metabolism was studied in patients with various endocrine hypofunctions. The results were compared with those of normal subjects. In adrenocortical insufficiency, hypothyroidism and hypopituitarism urinary excretion of carnitine was significantly lower than in normal subjects. On intramuscular injection of synthetic beta1-24 ACTH-Z urninary excretion of carnitine in normal subjects increased sixfold on the day of the injection and returned to the pretreatment level on the third day. Serum concentrations of carnitine and FFA increase in parallel with carnitine excretion, while serum triglyceride was lowered in response to ACTH administration. These responses were totally lacking or substantially suppressed in patients with the above endocrine insufficiencies. In hypothyroid and hypopituitary patients substitution therapy restored the responses to ACTH in the same fashion as those in normal subjects. These findings suggest that the promoting effect of ACTH on carnitine and lipid metabolism requires the presence of intact adrenocortical and thyroid functions.

Addison Disease↗
PubMed1976

A molecular orbital study on the interaction between the cytochrome P-450 and its substrates.

Models for the interaction of the cytochrome P-450 with its substrates, namely for the type I interaction are proposed in which the molecular planes of the aromatic substrate and the porphyrins of P-450 are in parallel. Optical values such as transition energies and oscillator strengths for the isolated P-450 and P-450-substrate complex are calculated by means of molecular orbital method (ASMO SCF CI method), and they are compared with the observed values. The fact that no appreciable shift in the absorption peak of Soret band of P-450 was observed upon addition of substrate is reflected well in the calculation. Similarly, the well-known fact that the absorbance of the P-450 was decreased by mixing it with the substrate is also explained well by the calculated oscillator strength for the isolated P-450 and the stacked complexes. From the good agreement between the calculated results and the observed ones, it is suggested that the proposed models might be true reflections of the interactions between the P-450 and its substrates.

Binding Sites↗