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Biomedical subjects

S Kitamura

Publications and source records attributed to S Kitamura.

At least 937 records · Page 52Linked to original sources
PubMed1983

Reductive metabolism of N-nitrosodiphenylamine to the corresponding hydrazine derivative.

The first evidence for the reductive metabolism of a noncyclic nitrosamine to the corresponding hydrazine derivative in vivo and in vitro is provided. Under anaerobic conditions, N-nitrosodiphenylamine was reduced by guinea pig liver 9000g supernatant to 1,1-diphenylhydrazine in the presence of 2-hydroxypyrimidine or to acetaldehyde diphenylhydrazone in the presence of acetaldehyde. These metabolites were identified unequivocally by comparative study with authentic samples. In addition, the study shows that such reductive reactions of the nitrosamine can be catalyzed by guinea pig and rabbit liver aldehyde oxidase in the presence of its electron donors. When the nitrosamine was given orally to acetaldehyde-treated guinea pigs, a metabolite was detected from plasma and identified as acetaldehyde diphenylhydrazone by comparison with the authentic sample.

Aldehyde Oxidase↗
PubMed1983

Changes of the pattern of biliary bile acids during isolated rat liver perfusion.

In spite of the extensive use of isolated perfused liver systems for bile acid related studies, the composition of biliary bile acids during liver perfusion is not well known. Using recently developed bioluminescence assays for 3 alpha-OH-, 7 alpha-OH-, and 12 alpha-OH- bile acids we studied the hydroxylation pattern of bile acids in bile during 90 minutes perfusion of isolated rat liver without added bile acid load. At the beginning 7 alpha-hydroxylated bile acids comprised more than 50% of total bile acids from male livers and more than 90% from female livers, this percentage declined rapidly during the first 40-50 minutes of perfusion to values between 10 and 20%. 12 alpha-hydroxylated bile acids comprised between 15 and 30% of the total at beginning of the perfusion and decreased to about 10% after 40 minutes. Sex differences as well as the influence of the duration of perfusion should be considered when the isolated perfused rat liver is used for bile acid related studies.

Animals↗
PubMed1983

Sulfoxide reductase activity of liver aldehyde oxidase.

The present study provides evidence that guinea pig and rabbit liver aldehyde oxidase (EC 1.2.3.1) in the presence of its electron donors such as aldehydes or N-heterocyclic compounds functions as a sulfoxide reductase towards sulindac and other sulfoxide compounds. In addition, the study shows that a combination of liver aldehyde oxidase and milk xanthine oxidase also exhibits sulfoxide reductase activity in the presence of xanthine, and electron donor of xanthine oxidase. Based on these facts, we propose a new electron-transfer system consisting of these two flavoenzymes.

Aldehyde Oxidase↗
PubMed1983

An improved method for transseptal left ventricular catheterization.

It is difficult to perform a retrograde left ventricular catheterization in patients having an aortic valve replacement. An improvement of the conventional transseptal catheterization (Brockenbrough method) led to a better success rate of catheterization. The fulcrum of the improved catheter was located 7 cm from the tip. Its curvature was approximately 270 degrees. Its tip was bent inward to form a pig-tail shape to prevent myocardial injury. This catheterization was performed 33 times in 32 patients. A 97% success rate was achieved. An exercise loading test was performed with a bicycle ergometer while this catheter was maintained in the left ventricle of a patient placed in a supine position. The catheter was well retained in the left ventricle and produced a minimal number of arrhythmias during exercise. The modification of this catheter has proved to be a better method of left ventricular catheterization in patients with an aortic valve replacement.

Adult↗
PubMed1983

Location of cell somata and the peripheral course of axons of the geniohyoid and thyrohyoid motoneurons: a horseradish peroxidase study in the rat.

The location of cell somata of the motoneurons supplying the rat geniohyoid and thyrohyoid muscles and the peripheral course of their axons were studied by intramuscular injection of horseradish peroxidase in combination with severing the innervating nerves of these muscles. Labeled geniohyoid motoneurons were found ipsilaterally in the ventrolateral subnucleus of the hypoglossal nucleus, which separates at midlevel of this nucleus from the main hypoglossal nucleus lying near the central canal and finally projects to the dorsomedial part of the ventral horn in the transition level of the brain/spinal cord. Geniohyoid motoneuron axons mostly pass through the hypoglossal nerve, whereas axons of the motoneurons in the transition level, though much fewer in number, pass through the first cervical nerve. Labeled thyrohyoid motoneurons were found ipsilaterally to form a cell column that extends from the caudal end of the main hypoglossal nucleus in the transition level of the brain/spinal cord to the dorsomedial part of the ventral horn in the caudal first cervical segment. All their axons passed through the first cervical nerve, and thus, the rostral portion of the thyrohyoid motoneuron column, which appears to be part of the hypoglossal nucleus, is not included in this nucleus but constitutes the supraspinal nucleus, which connects the hypoglossal nucleus to the ventral horn motoneuron group. The mean cell body sizes of the geniohyoid and thyrohyoid motoneurons were 28.7 +/- 4.4 and 29.3 +/- 4.6 micrometers, respectively, and their cell body size distributions were unimodal.

Animals↗
PubMed1983

Effect of lipoxygenase inhibitors, AA-861 and T-22083, on chemical mediators released from sensitized guinea-pig lung tissue.

Male Hartley strain guinea pigs weighing about 200g were used as the experimental animals. Histamine and SRS-A released from the lung tissue were measured by the bioassay methods. The amount of histamine released from passively sensitized lung tissue by the challenge of antigen showed marked decrease by preincubating with AA-861 or T-22083, and the percentage inhibition by AA-861 was greater than that by T-22083. The amount of SRS-A released from sensitized lung tissue by the challenge with antigen showed marked decrease by preincubation with AA-861 or T-22083, and the percentage inhibition by AA-861 was greater than that by T-22083. The above results suggest that AA-861 and T-22083 have not only an inhibitory action on the release of SRS-A from sensitized lung tissue but also have an inhibitory action on the release of histamine.

Animals↗
PubMed1983

Surgery for coronary heart disease due to mucocutaneous lymph node syndrome (Kawasaki disease). Report of 6 patients.

Early and late surgical results in 6 patients with coronary heart disease secondary to mucocutaneous lymph node syndrome (MLNS) (Kawasaki disease) are presented. There were 5 male patients and 1 female patient, ranging in age from 2.5 to 26 years at the time of operation. They had severe coronary artery narrowings, obstructions, and aneurysms with or without mitral regurgitation. Previous myocardial infarction was documented in 5 patients. Aortocoronary bypass grafting utilizing the autologous saphenous vein was performed in 5 patients; in the remaining patient, mitral valve replacement was carried out. No operative or late deaths have been encountered. A long-term bypass graft patency was demonstrated in patients aged 26, 17, and 10 years with resulting clinical, angiographic, or scintigraphic improvements, or a combination of these. However, the graft that had been patent in a 4-year-old boy was found completely obstructed 3 years after surgery without any symptomatic changes. The formation of rich collateral channels was found. The risk of saphenous vein graft closure may be high in young growing children. In older children or adolescents, however, coronary vein bypass grafting for this specific inflammatory coronary artery lesion has been effective with long-term graft patency. Severe mitral regurgitation is also an indication for surgery, but poor left ventricular function associated with mitral regurgitation, probably secondary to myocarditis, persists after surgery and may give rise to future problems.

Adolescent↗
PubMed1983

Operative results in patients with pseudotruncus arteriosus.

Total repair was carried out in 18 patients with pseudotruncus arteriosus. Age at the time of operation ranged from 1 to 25 years and averaged 9 years. Operative methods were transannular patch reconstruction for the relief of pulmonary atresia in 4 patients (no deaths) and reconstruction with a valved external conduit from the right ventricle to the pulmonary arteries in 14 patients (5 deaths). The overall operative mortality was 28%. An average cross-sectional area of the right and left pulmonary arteries (PA area) was calculated using angiograms and compared with the cross-sectional area of the normal right pulmonary artery (N-rPA area) in all patients. The PA area ranged from 0.06 to 2.60 cm2 and averaged 1.02 cm2; the PA area/N-rPA area ratio ranged from 0.03 to 1.05, with an average of 0.54. Three patients who died of hypoplastic right and left pulmonary arteries had a PA area/N-rPA area ratio less than 0.20. These patients had a right-to-left ventricular peak systolic pressure ratio (pRV/LV) greater than 1.0 after total repair. Fifteen patients had a PA area/N-rPA area ratio greater than 0.20, and 13 survived corrective procedures. One patient died of lung edema, which was due to failure to ligate the large bronchial collateral artery properly, and the other died of pulmonary vascular obstructive disease. Our results show that a PA area/N-rPA area ratio greater than 0.20 is a necessity in performing total repair of pseudotruncus arteriosus.

Adolescent↗
PubMed1983

Studies on bacterial nitroreductases. Enzymes involved in reduction of aromatic nitro compounds in Escherichia coli.

Enzymes involved in reduction of methyl p-nitrobenzoate in Escherichia coli B/r were oxygen-insensitive and precipitated between 30 and 60% ammonium sulfate saturation from cell-free extracts of the strain. The reductases were resolved by DEAE-cellulose column chromatography into three enzymes, NADH-linked, NAD(P)H-linked and NADPH-linked ones. These enzymes were flavoprotein which could be inactivated by dialysis against 1 M potassium bromide and could be reactivated by FMN. The NADH-linked and NAD(P)H-linked reductases were sensitive to dicumarol and exhibited menadione reductase activities. Aromatic nitro compounds with electron-withdrawing p-substituents were easily reduced by the NAD(P)H-linked reductase.

Cell-Free System↗
PubMed1983

Involvement of liver aldehyde oxidase in conversion of N-hydroxyurethane to urethane.

The present study provides the evidence that liver aldehyde oxidase in the presence of its electron donors can catalyze the reduction of N-hydroxyurethane to urethane under anaerobic conditions. Guinea pig liver 9000 X g supernatant and cytosol, but not liver microsomes, exhibited N-hydroxyurethane reductase activity in the presence of acetaldehyde or 2-hydroxypyrimidine. The cytosolic enzyme was precipitated with ammonium sulfate between 30 and 45% ammonium sulfate saturation. The N-hydroxyurethane reductase and aldehyde oxidase activities of the precipitate were similarly susceptible to inhibition by a variety of chemicals. When the precipitate was chromatographed on a DEAE-cellulose column, the elution peak position of N-hydroxyurethane reductase was entirely identical with that of aldehyde oxidase. Furthermore, purified rabbit liver aldehyde oxidase also exhibited a significant N-hydroxyurethane reductase activity in the presence of acetaldehyde or 2-hydroxypyrimidine.

Aldehyde Oxidase↗