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Biomedical subjects

Y Imamura

Publications and source records attributed to Y Imamura.

At least 361 records · Page 20Linked to original sources
PubMed1987

A comparative study of the interaction of warfarin with human alpha 1-acid glycoprotein and human albumin.

The interaction of warfarin with human alpha 1-acid glycoprotein (alpha 1-AGP) and human albumin (HA) has been investigated using fluorescence and circular dichroism techniques. The fluorescence of warfarin is greatly enhanced following binding to alpha 1-AGP or HA, the binding constant for a single site being estimated by the Scatchard method. The binding constants for the two serum proteins are similar, but the thermodynamic parameters differ. The binding constants increase as the pH is raised to 9.0. Various basic drugs, such as chlorpromazine, propranolol and imipramine, markedly inhibited the binding of warfarin to alpha 1-AGP. But, some acidic drugs, including phenylbutazone, effectively displaced warfarin bound to HA. The difference in CD spectra observed for alpha 1-AGP and HA indicated that the drug-binding sites of the two proteins might have different asymmetries. It thus appears that the mode of interaction of warfarin with the two proteins differs.

Circular Dichroism↗
PubMed1987

Molecular basis of enzyme abnormalities in urea cycle disorders. With special reference to citrullinemia and argininosuccinic aciduria.

This paper deals with enzymological, immunochemical and molecular genetic analyses of citrullinemia and argininosuccinic aciduria. Citrullinemia has been classified by Saheki et al. [J. inher. Metab. Dis. 8: 155-156, 1985] into three types from the properties of the deficient argininosuccinate synthetase (ASS) of the patients. Analysis of hepatic mRNA coding for ASS revealed certain characteristics in type II and III citrullinemic patients whose hepatic ASS protein was low. A newly developed enzyme-linked immunosorbent assay (ELISA) of argininosuccinate lyase (ASL) protein showed that 8 out of ten cases of argininosuccinic aciduria had no detectable ASL protein in the liver, erythrocytes, cultured skin fibroblasts or cultured amniocytes.

Amino Acid Metabolism, Inborn Errors↗
PubMed1987

Sex difference of acetohexamide reduction in rat liver.

The acetohexamide reducing activity in hepatic 10,000 X g supernatant was significantly higher in male than in female rats. Evidence obtained in this study suggests that the microsomal carbonyl reductase may contribute to the sex difference in the reductive metabolism of acetohexamide in rats.

Acetohexamide↗
PubMed1987

Marked increase in serum alpha-fetoprotein level in cirrhosis: a case report.

A 56-yr-old Japanese man with chronic liver disease was admitted for evaluation of increased serum alpha-fetoprotein reaching levels as high as 7190 ng/ml. The presence of hepatocellular carcinoma was ruled out by computed tomography and hepatic angiography. Laparoscopy and liver biopsy sample showed active liver cirrhosis. alpha-Fetoprotein granules were positive in hepatocytes. The rise in serum alpha-fetoprotein level was transitory and returned to less than 100 ng/ml 4 wk later. It was suggested that regeneration after acute exacerbation of cirrhosis might have been closely related to the dramatic increase in alpha-fetoprotein production.

Chronic Disease↗
PubMed1987

[Malignant lymphoma differentiated to plasma cell of the testis: report of a case].

Malignant lymphoma of the left testis was seen in a 53-year-old man. Pathologically, the tumor cell showed malignant lymphoma of the diffuse, small cell type, especially, of lympho-plasmacytoid in LSG classification. Clinically, no other lesions were found. At 26 months following orchiectomy with chemotherapy (CHOP regimen: cyclophosphamide, hydroxydaunomycine, vincristine and prednisone) as well as post-operative irradiation (60Co, 30 Gy.), the patient has been doing well without any clinical evidence of recurrence generalization of the tumor.

Adult↗
PubMed1987

[Apnea test essential in the diagnosis of brain death].

We experienced 11 cases of brain death for the past two years, in six of whom we performed the apnea test to confirm the cessation of the medullary respiratory functions. The cause of brain death was primary intracranial lesions in four, subarachnoidal hemorrhages in three and meningitis in one. Hypoxia of the brain secondary to cardiac arrest resulted brain death in the remaining two cases. Blood gases were analysed before (control) and after pre-oxygenation, after having adjusted PaCO2 around 40 mmHg, and every three minutes after disconnection from the respirator. Blood pressure and other vital signs were monitored through out the test. PaCO2 was brought to 40 mmHg by reducing the respiratory rate in three cases, by decreasing the tidal volume following the reduction of the respiratory rate in one case and by applying the bicarbonate gas in one case. The mean PaCO2 level was 46.2 +/- 6.0 mmHg. No one regained the respiration during 10 minutes of the apnea test. In one case, the oxygen catheter was not inserted deeply enough into the tracheal tube, resulting the fall of blood pressure and necessitating termination of the test six minutes after disconnection from the respirator. This case was not included for further analysis. The pH and PaCO2 did not change significantly after pre-oxygenation and after adjusting of PaCO2. Only the PaO2 increased significantly after preoxygenation. PaCO2 increased with the rate of 3.04 +/- 1.2 mmHg/min up to 73.4 +/- 15.6 mmHg and pH decreased with the rate of 0.016 +/- 0.007 down to 7.1 +/- 0.03 after disconnection from the respirator.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Limited tryptic digestion of Ca2+,Mg2+-adenosine triphosphatase of the sarcoplasmic reticulum: enzymatic properties of A1b + B complex.

Sarcoplasmic reticulum membranes were treated with trypsin under conditions leading to accumulation of B and three other fragments a little smaller than A1, namely A1a, A1b, and C (Mr 27,000-28,000) (Saito, K. et al. (1984) J. Biochem. 95, 1297-1304), and enzymatic properties of trypsin-digested ATPase were investigated. The tryptic cleavage pattern of SR membranes in the presence of 1 M glycerol and 5 mM CaCl2 at 35 degrees C was qualitatively similar to that obtained in the presence of Ca2+ alone. However, considerably more A1-derived fragments, A1a and A1b, which are stabilized by the binding of Ca2+ to the enzyme, were accumulated. The sample digested under this condition for 60 min was mainly composed of A1b and B, and was designated as A1b + B complex. ATPase activity was lost in parallel with the formation of A1a and A1b. On the other hand, E-P forming activity was still retained by A1b + B complex. E-P formation with this complex was strictly dependent on the presence of Ca2+ ions at micromolar concentration. This indicates that Ca2+ binding site is well conserved in this complex. E-P formed with A1b + B complex was ADP-sensitive (E1-P), and was not further decomposed, since the transition from E1-P to E2-P was blocked.

Adenosine Diphosphate↗
PubMed1986

Degradation of insulin by insulin-degrading enzyme and biological characteristics of its fragments.

We have previously reported on the purification, characterization, and biological significance of insulin-degrading enzyme (IDE) from pig and rat skeletal muscle. In the present study, we have investigated the detection and the HPLC separation of degradation products of native insulin from the reaction of monocomponent porcine insulin with affinity-purified pig IDE. Insulin was degraded by IDE in a time- and dose-dependent manner. Eight peaks (peaks I through VIII) appeared after 1 h of incubation, and peak V was identified as insulin. Among seven peaks representing degradation products, peak VI appeared most rapidly at 30 sec of incubation, increased until 10 min, and then decreased after 15 min of incubation; and six degradation products other than peak VI were not detected within 15 min of incubation, suggesting that peak VI was an initial degradation product of insulin produced by IDE and converted into relatively low molecular weight products as incubation time increased. The generation of peak VI may be due to cleavage at a peptide bond between the interchain disulfide bonds of the A or B chain. Subsequently, the split insulin derivative (peak VI) was evidently further degraded to relatively low molecular weight intermediates, such as peaks III and IV, peaks II and VIII, or peaks I and VII, because these pairs of peaks appeared and were degraded concomitantly. The peptide products designated as peaks IV, VI, VII, and VIII had both immunoprecipitability by antiinsulin antibodies and binding capacity to IM-9 lymphocytes, whereas the less hydrophobic intermediates (peaks I, II, and III) did not have these activities. Since some of these peptides have insulin-like properties, amino acid analysis of these products may enable us to identify not only the splitting position of insulin by IDE but also the site of the hormone for receptor binding.

Animals↗
PubMed1986

Reduction of acetohexamide by rabbit heart cytosol.

The acetohexamide reducing activity of cytosol of rabbit heart was compared with that of rabbit liver or kidney. The heart exhibited an approximately 2-fold higher activity than either the liver or kidney. Both aldehyde and ketone reductases may contribute to the reduction of acetohexamide by cytosol of rabbit heart. It is noteworthy that the heart is an important organ reducing acetohexamide.

Acetohexamide↗
PubMed1986

Effect of phenylbutazone on serum protein binding of sulfadimethoxine in different animal species.

The effect of phenylbutazone (PBZ) on the in vivo serum protein binding of sulfadimethoxine (SDM) was examined in dogs, rabbits and rats. In dogs, PBZ itself was found to displace SDM from its protein binding sites. In rabbits, PBZ indirectly reduced the in vivo serum protein binding of SDM through the interaction of PBZ with N4-acetylsulfadimethoxine (N4-AcSDM), a major metabolite of SDM. In rats, however, PBZ had no effect on the in vivo serum protein binding of SDM. It is noteworthy that species differences were observed in the effect of PBZ on the in vivo serum protein binding of SDM.

Animals↗