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Biomedical subjects

R Yamada

Publications and source records attributed to R Yamada.

At least 253 records · Page 14Linked to original sources
PubMed1985

Factors stabilizing pyrroline-5-carboxylate synthase of rat intestine mucosa at a physiological temperature.

Mammalian pyrroline-5-carboxylate (PC) synthase in the mitochondrial membrane of rat small intestine mucosa possesses marked thermal instability at temperatures of 30 to 37 degrees C [Y. Wakabayashi, J. G. Henslee, and M. E. Jones (1983) J. Biol. Chem. 258, 3873-3882]. Factors stabilizing the enzyme activity at 37 degrees C were extensively examined by incubating the enzyme with various compounds before assay. In the presence of 60% sorbitol, the enzyme retained full activity for 30 min. Xylitol, glycerol, and fructose were also effective, although sucrose, ethylene glycol, polyethylene glycol and dimethyl sulfoxide were ineffective. AMP, GMP, IMP, and UMP (15 mM) were completely protective while ATP and adenosine were not. Phosphate and arsenate at 10 mM maintained 90 and 82%, respectively, of the original activity after 10 min. NADPH and NADP (3 mM) were protective whereas 3 mM NADH was not. The possibility that phosphate and NADPH are stabilizing PC synthase in vivo was discussed. Addition of 0.13 mM p-chloromercuriphenylsulfonic acid or 0.55 mM 5,5'-dithiobis-(2-nitrobenzoic acid) to the enzyme resulted in complete loss of activity, but prior addition of excess dithiothreitol to the enzyme prevented the inactivation, suggesting that a sulfhydryl group is involved in the activity.

Adenosine Monophosphate↗
PubMed1985

Temperature- and time-dependent inactivation of pyrroline-5-carboxylate synthase: suggestive evidence for an allosteric regulation of the enzyme.

When pyrroline-5-carboxylate (PC) synthase activity in the membrane of mitochondria of rat small intestine mucosa was assayed in the presence of 0.5 mM ornithine, the time course of inactivation showed that the activity disappeared entirely by about 8 min at 30 degrees C, whereas there was no decrease in the activity at 15 degrees C. A prior incubation of the enzyme with ornithine at 30 or 37 degrees C in the presence of 50% sorbitol as a thermal stabilizer resulted in a marked loss of the activity, while that at 0 or 15 degrees C did not lose any. This suggests that PC synthase is inactivated by ornithine regardless of the presence of substrates. The inactivation at 30 degrees C proceeded gradually for about 7 h, until an equilibrium was attained. Extensive dialysis allowed the inactivated enzyme to regain about 60% of the original activity. These results suggest that the inactivation is reversible. The concentration of ornithine and the percentage of inactivation at equilibrium was correlated by the Hill equation and displayed a sigmoidicity with n = 1.47 and [S]50 = 0.036 mM. In the presence of sorbitol, the inactivation was prevented by 0.2 mM ATP or ADP. The role of the nucleotides in PC synthase regulation is discussed.

Adenine Nucleotides↗
PubMed1985

In vitro degradation of oxytocin by pregnancy serum, placental subcellular fractions and purified placental aminopeptidases.

The degradation of oxytocin (formula; see text) by human placental particulate and soluble fractions, pregnant and non-pregnant sera, and purified enzymes such as microsomal placental leucine aminopeptidase (P-LAP), retroplacental serum P-LAP and placental post-proline endopeptidase, was studied by measuring liberated amino acids with a high performance liquid chromatograph (HPLC). While the placental particulate fraction degraded oxytocin almost completely into single amino acid and amide, the placental soluble fraction did not liberate any amino acid and amide. Purified retroplacental P-LAP liberated Tyr2, Ile3, Gln4 and Asn5 from the cyclic structure of oxytocin actively. Pregnancy serum containing the retroplacental P-LAP liberated also these amino acids and amides. Purified microsomal P-LAP liberated Leu8 in addition to these amino acids and amides. Although purified placental post-proline endopeptidase or porcine kidney leucine aminopeptidase (LAP) could not liberate any amino acid and amide from oxytocin, the combination of the post-proline endopeptidase with porcine kidney LAP or with placental microsomal P-LAP actively liberated all amino acids and amides detectable by HPLC. When the ratio of amino acid liberation velocity to LAP activity measured with leu-p-nitroanilide was calculated, the ratios for cyclic amino acids such as Tyr2 and Ile3 were high with the placental particulate fraction, the mixture of post-proline endopeptidase and microsomal P-LAP, retroplacental P-LAP, and pregnancy serum. The ratio for Leu8 was high with the placental particulate fraction and the mixture of post-proline endopeptidase and microsomal P-LAP.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1985

[Automatic collection system of waste scintillator solution using micro robots].

Industrial micro-robots are now being applied to hazardous jobs or tedious jobs. These in-house micro-robots (MELFA, RM-501, Mitsubishi Electric Inc.) were used to make a collection system of waste scintillator solution on the experimental basis. Newly developed were hands, vial holders and a system soft ware, and satisfactory results have been obtained.

Automation↗
PubMed1985

[Clinical studies with cefoperazone in the biliary disease].

The concentration of cefoperazone (CPZ) in serum and bile was estimated after intravenous drip infusion of 1 g of the drug in 11 patients, who have performed cholecystectomy, choledocholithotomy and T-tube drainage for gallstone diseases. Administration of cefazolin (CEZ) 1 g was compared by the cross over method. After 1 g intravenous drip infusion of CPZ, the mean serum concentration was 88.3 +/- 24 micrograms/ml at 1 hour, 52 +/- 11.7 micrograms/ml at 2 hours and 36.5 +/- 10 micrograms/ml at 4 hours. The maintenance period of serum concentration was inclined to be longer in CPZ than in CEZ. After 1 g intravenous drip infusion of CPZ, the mean bile concentration reached to 810 +/- 459 micrograms/ml in 2 hours and it was maintained as high as 562 +/- 319 micrograms/ml even after 4 hours. On the other hand, after 1 g intravenous drip infusion of CEZ, the mean bile concentration was only 28.7 +/- 26 micrograms/ml in 1 hour and was low level in the progress. As compared with the highest concentration of CPZ and CEZ in same patient, the mean bile concentration of CPZ (942 +/- 525 micrograms/ml) was about 30 times higher than that of CEZ (28.6 +/- 26.3 micrograms/ml). There was no difference in the group of Gram-positive cocci between minimum inhibitory concentration (MIC) of CPZ and that of CEZ. While MIC of CEZ in the group of Gram-negative bacilli was from 0.78 to over 400 micrograms/ml, MIC of CPZ in that group was from 0.10 to 50 micrograms/ml. The value in CPZ was lower than that in CEZ at all strains. No side effects was seen in all patients.

Adult↗
PubMed1985

[Two cases of early squamous cell carcinoma of the hilar region of the lung cured by bronchofiberscopic excision].

We experienced two patients with early squamous cell carcinoma at the hilar region of the lung. The carcinoma were completely eliminated by tumor biopsy using a bronchofiberscope. In both cases, there was either pulmonary tuberculosis or a second primary lung cancer (bronchiolo-alveolar carcinoma) on the contralateral side. After bronchoscopic excision of the tumor, the patients were closely observed using by repeat bronchoscopy at 5 to 6 week intervals. One patient is free of recurrence at 4.5 years after treatment and is deemed to be cured. The other patient died of recurrence and metastasis from a second primary bronchioloalveolar carcinoma at 1 year and 5 months after treatment, however he had no recurrence of the squamous cell carcinoma.

Aged↗
PubMed1984

Hematoporphyrin derivative and photoradiation therapy in early stage lung cancer.

Photoradiation therapy (PRT) with administration of hematoporphyrin derivative (HPD) was performed in ten cases of early stage central-type lung cancer of which six cases were treated by PRT alone due to inoperability because of poor pulmonary function in five and refusal of surgery in one. Four cases were resected after PRT. In the former, complete tumor remission was obtained in all six and in the latter, complete tumor remission was seen in one and significant remission in three. In the nonresected cases four cases are disease-free at 17-41 months and the remaining two cases died of chronic obstructive lung disease and cerebral infarction 16 and 31 months after PRT, respectively. The resected cases are disease-free 7-32 months after surgery. Indications of PRT in early stage lung cancer are discussed according to histological findings of resected specimen.

Aged↗
PubMed1984

A one-step assay for pyrroline-5-carboxylate synthase using a short AG1-X8 column.

A rapid and simple method for assay of pyrroline-5-carboxylate synthase is presented. In this method, the incubation is terminated by raising the pH of incubation mixture to 10, and [14C]pyrroline 5-carboxylate produced from the substrate, [14C]glutamate, is first converted quantitatively to [14C]proline by reduction with NaBH4 at pH 10 and then the proline is allowed to pass through column of AG1-X8 anion exchanger under the conditions where the glutamate is completely retained by the column. Radioactive counting of the eluate gives the synthase activity. The entire procedure takes only one hour.

Animals↗
PubMed1984

[Surgical indications of small cell carcinoma of the lung].

A statistical analysis of 143 cases of small cell carcinoma treated at the Department of Surgery of Tokyo Medical College in the 15-year period from January 1968 to December 1982 was performed. The results suggest that surgery is not indicated in any oat cell case, with the possible exception of an extremely rare early stage case. However, since here is a significant difference in the survival of stage I and II cases of the intermediate cell type, surgery can be indicated in certain such cases. Even in such cases surgery should be thought of as merely one step of induction therapy. In addition, it is necessary to tailor adjuvant chemotherapy, keeping in mind that the most frequent causes of death in cases of small cell carcinoma of the lung are local failure, metastasis to intraabdominal organs and to the brain.

Carcinoma, Small Cell↗