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I Uchida

Publications and source records attributed to I Uchida.

At least 19 recordsLinked to original sources
PubMed1992

Molecular studies of parental origin and mosaicism in 45,X conceptuses.

The present report summarizes molecular studies of parental origin and sex chromosome mosaicism in forty-one 45,X conceptuses, consisting of 29 spontaneous abortions and 12 liveborn individuals with Turner syndrome. Our studies indicate that most 45,X conceptuses have a single, maternally derived X chromosome, regardless of whether the conceptus is liveborn or spontaneously aborted. In studies of mosaicism, our identification of X- and Y-chromosome mosaics among 45,X spontaneous abortions indicates that mosaicism does not ensure survival to term of 45,X fetuses. However, the incidence of sex chromosome mosaicism is substantially higher in liveborn than in aborted 45,X conceptuses, indicating that the presence of a second cell line increases the likelihood of survival to term.

Abortion, Spontaneous↗
PubMed1992

Prolongation of canine epidural anesthesia by liposome encapsulation of lidocaine.

The purpose of our study was to produce a long-acting lidocaine by using a liposome that would entrap the drug. Egg yolk phosphatidylcholine and cholesterol were used as liposome materials. After epidural administration, the pharmacodynamics and pharmacokinetics of liposomal and free lidocaine were studied in 20 dogs. Two percent liposomal or free lidocaine (3.0 mL) was injected into the lumbar epidural space. Nerve blocking effects were estimated by measuring somatosensory evoked potentials. Recovery time from the epidural block in the liposomal lidocaine group (170 +/- 49.5 min) was approximately three times longer than that in the free lidocaine group (61 +/- 18.1 min). The areas under the drug concentration-time curves (AUC0-infinity) and time to maximal concentration (Tmax) in the liposomal lidocaine group were significantly larger than those in the free lidocaine group. These results suggest that the prolongation of epidural blockade by liposomal lidocaine is caused by a slow release of the drug from liposomes. The present study suggests that liposomal lidocaine can be used as a long-acting local anesthetic.

Amines↗
PubMed1992

[Calculation algorithm of three-dimensional absorbed dose distribution due to in vivo administration of nuclides for radiotherapy].

In the in vivo administration of radionuclides for radiotherapy including radioimmunotherapy, an algorithm is proposed for the purpose of calculating three-dimensional absorbed dose distributions of tumors and adjacent tissues, and neighboring organs. The absorbed dose distribution due to the algorithm is given by convolution of the three-dimensional dose matrix for a unit cubic voxel containing unit cumulated activity, with the three-dimensional matrix of the cumulated activity distribution given by the same voxel size above. The dose calculation algorithm does not depend upon the source size, the source shape, and the nonuniform and irregular activity distribution. In addition, it can exceedingly decrease computation time compared to other calculation algorithms. Computer simulations were performed using the MIRD thyroid phantom for 32P, 90Y, 131I, 186Re, and 188Re that appear promising for radioimmunotherapy, and their results verified the validity of the proposed calculation algorithm and high accuracy of the calculations.

Algorithms↗
PubMed1991

Effects of volatile anesthetics on bacteriorhodopsin in purple membrane, Halobacterium halobium cells and reconstituted vesicles.

In this study, we have investigated effects of volatile anesthetics on absorption spectra, proton pumping activity and decay of photointermediate M of bacteriorhodopsin (bR) in differently aggregated states. Anesthetics used in this study are ether-type general anesthetics; enflurane and sevoflurane. The observed effects on bR depend not only on variety or concentration of anesthetics but also strongly on the aggregation state of bR molecules in the membrane. In purple membrane (PM), bR having maximum light absorption at 567 nm (bR567) is formed in the presence of sevoflurane or a small amount of enflurane, while a species absorbing maximally at 480 nm (bR480) is formed upon the addition of large amounts of enflurane. X-ray diffraction studies show that the former species maintains crystallinity of PM, but the latter does not. In reconstituted vesicles where bR molecules exist as monomer, even sevoflurane forms bR480. Flash photolysis experiments show that bR567 contains a shorter-lived M intermediate absorbing maximally at 412 nm in the photoreaction cycle than bR does and that bR480 contains at least two long-lived M intermediates which seem to absorb maximally near and at lower than 380 nm. The measurements of light-induced pH changes of the whole cells and of the reconstituted vesicles in the presence of the anesthetics indicate that bR567 has a enhanced proton pumping efficiency, while bR480 has a quite low or no activity. No significant difference was observed in the anesthetic action between two inversely pumping vesicles. These observations suggest that on the formation of bR480, anesthetics enter into the membrane and affect the protein-lipid interaction.

Anesthetics↗
PubMed1991

Immobilized-enzyme electrode for nicotinamide adenine dinucleotide (reduced form) (NADH) sensing and application to the kinetic studies of NADH dependent dehydrogenases.

Amperometric determination of nicotinamide adenine dinucleotide (reduced form) (NADH) at an immobilized-diaphorase (Dp) electrode is described. The measurement was conducted using ferrocenylmethanol as a mediator in a stirred solution at 0.20 V versus a saturated calomel electrode. A linear relationship between the steady-state current and the concentration of NADH was found over the range 0.005-0.125 mmol dm-3. The immobilized-Dp electrode showed outstanding stability and the current response reached a steady state within 2-3 seconds upon addition of NADH. The proposed electrode was used to follow the reactions of pig heart lactate dehydrogenase and horse liver alcohol dehydrogenase. The kinetic investigation using the immobilized-Dp electrode gave the kinetic parameters (Michaelis constants, Km values, and maximum velocities, Vm values), which were in satisfactory agreement with those determined by a conventional spectrophotometric method.

Electrodes↗
PubMed1991

Trisomy 21: association between reduced recombination and nondisjunction.

To assess the association between recombination and nondisjunction of chromosome 21, we analyzed cytogenetic and DNA markers in 104 trisomy 21 individuals and their parents. Our DNA marker studies of parental origin were informative in 100 cases, with the overwhelming majority (94) being maternal in origin. This value is significantly higher than the 75%-80% maternal nondisjunction rate typically observed in cytogenetic studies of trisomy 21 and illustrates the increased accuracy of the molecular approach. Using the maternally derived cases and probing at 19 polymorphic sites on chromosome 21, we created a genetic map that spans most of the long arm of chromosome 21. The map was significantly shorter than the normal female linkage map, indicating that absence of pairing and/or recombination contributes to nondisjunction in a substantial proportion of cases of trisomy 21.

Adult↗
PubMed1990

Electron transferase activity of diaphorase (NADH: acceptor oxidoreductase) from Bacillus stearothermophilus.

Electrochemical kinetic measurements were carried out for electron-transfer between NADH and the oxidized forms of mediators (ferrocenylmethanol (FMA), ferrocenyl-1-ethanol (FEA), N,N,N',N'-tetramethylphenylenediamine (TMPD), Co(Phen)2+(3) and Fe(CN)4-(6)) catalyzed by diaphorase (NADH: acceptor oxidoreductase, EC 1.6.99.-) purified from Bacillus stearothermophilus. Cyclic voltammograms for the mediators with excess NADH in the presence of diaphorase gave steady-state currents. The quantitative analysis of the dependence of the current on the mediator concentration yielded a Michaelis constant (Km) and molecular activity (ko), which are difficult to determine by the conventional spectrophotometric method. Small Km and large ko values were observed for the oxidized forms of FMA, FEA and TMPD compared to those for Co(Phen)3+(3) and Fe(CN)3-(6). It is suggested that the reaction pocket of the present diaphorase is hydrophobic. The present electrochemical procedure for the determination of the kinetic parameters is applicable widely to similar enzyme reactions.

Amino Acids↗
PubMed1990

Nondisjunction of chromosome 21.

Chromosome heteromorphisms and restriction fragment length polymorphisms were used to study the origin of the extra chromosome in 54 trisomy 21 conceptuses. The parental origin was determined in 43 cases, with 39 (91%) being maternally and 4 (9%) parentally derived. Analysis of recombination demonstrated the presence of one or two cross-overs in most cases for which sufficient information was available, suggesting that failure to pair/exchange at meiosis I is relatively unimportant in the genesis of trisomy 21.

Adult↗
PubMed1990

Large exostosis of the mandibular coronoid process. Report of a case.

The clinical experience of a patient with a large exostosis who had a chief complaint of difficulty in opening the mouth is reported. Radiographic examinations, especially tomography and a CT scan, were useful in the diagnosis. Surgical removal is the treatment of choice. The lesion is usually approached by a combination of intraoral and buccal routes; we also employed such an approach in this particular case.

Adolescent↗