Biomedical subjects
Publications and source records attributed to R Yamada.
Serum aminopeptidase A (AAP) activity was measured in normal pregnancy and pre-eclampsia. The AAP activity in normal pregnancy increased progressively with advancing gestation, reaching the highest value at the end of pregnancy. The AAP activity in pregnancy complicated by pre-eclampsia was lower than in normal pregnancy.
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In order to evaluate the gastric emptying and postprandial mixing of bile with food, the scintigraphies of hepatobiliary and gastrointestinal tracts by using three different kinds of radioisotopes were performed simultaneously (99mTc-E.HIDA for hepatobiliary scintigraphy, 111In-DTPA containing orange juice and 131I-albumin containing scrambled egg for gastrointestinal scintigraphy). This method was available for observation of gastric emptying of liquid and solid foods and also examination of the mixing effect of bile and food quantitatively.
In order to evaluate the clinical application of the calcium absorption test from the intestine, the intestinal 47Ca absorption test by using a scintillation camera was carried out in our laboratory. The results in the intestinal 47Ca absorption test using a scintillation camera showed a good correlation to the results which were estimated by using an arm counter previously reported by us. The rate of intestinal 47Ca absorption in 8 healthy volunteers (5 male, 3 female, average age: 37.6 +/- 9.5 years) was 52.0 +/- 3.8%, 74.3% in a patient with primary hyperparathyroidism 30.4% and 32.7% in two patients with idiopathic hypoparathyroidism respectively. This method is more easily handled and can be performed for only 4 days in institutes that are set up with scintillation camera without any special preparations, and it is recommended to be of clinical usefulness for the diagnosis of calcium metabolic disorders.
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L-Hydrazinosuccinate has been reported to be a slow- and tight-binding inhibitor of aspartate aminotransferase (L-aspartate: 2-oxoglutarate aminotransferase, EC 2.6.1.1) and to interact with the enzyme via a reaction of two consecutive steps. The present work examined the effects of D-hydrazinosuccinate on the same enzyme for comparison. D-Hydrazinosuccinate showed a potent inhibition in a slow-binding manner: transamination became slower with time when the reaction was initiated by the addition of enzyme to a mixture of the assay components and D-hydrazinosuccinate, while the reaction was initially very slow and became faster with time when the enzyme was preincubated with the inhibitor before the initiation of reaction. Analysis of the time-course of interaction of the enzyme with D-hydrazinosuccinate suggested a reversible single-step reaction mechanism and gave an inhibition constant of approx. 3 nM, in contrast to the two-step mechanism, and a much lower inhibition constant of 0.2 nM for L-hydrazinosuccinate. Comparison of the rate constants for the reaction steps in the interaction of the enzyme with D- and L-enantiomers confirmed that the difference in the reaction mechanism was mainly responsible for the stronger inhibition by the L-enantiomer. Spectral studies showed that D- and L-hydrazinosuccinate both produced complexes with the enzyme probably in the form of aldimine, and thereafter only the complex with L-hydrazinosuccinate further changed to another species more slowly, consistent with the two-step mechanism. The configuration of the hydrazino group is therefore crucial for the conversion of aldimine complexes to more tightly bound complexes.
Lipocortin is a phospholipase inhibitory protein whose synthesis is induced in various cells by glucocorticoids. At least three species with molecular weights of 40,000, 30,000, and 15,000 are presently known. This protein mimics the anti-inflammatory action of glucocorticoids in vitro as well as in vivo. The synthesis of the protein appears to be associated with the MHC genes.
A rare case of giant cell tumor occupying the infratemporal fossa is reported. The site of origin was obscure, although the tumor had obviously eroded a portion of the zygomatic arch and involved the outer cortex of the temporal bone. Aggressive surgical ablation is suggested as the primary treatment of choice for giant cell tumors in any location. Long-term follow-up evaluation is also necessary.
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