Search PubMed⌕ Search

Biomedical subjects

S Usui

Publications and source records attributed to S Usui.

At least 109 records · Page 6Linked to original sources
PubMed1991

Immunochemical study of subunit VI (Mr 13,400) of mitochondrial ubiquinol-cytochrome c reductase.

A preparation containing the Mr 13,400 protein (subunit VI), phospholipid, and ubiquinone was isolated from bovine heart mitochondrial ubiquinol-cytochrome c reductase by a procedure involving Triton X-100 and urea solubilization, calcium phosphate-cellulose column chromatography at different pHs, acetone precipitation, and decanoyl-N-methylglucamide-sodium cholate extraction. The protein in this preparation corresponds to subunit VI of ubiquinol-cytochrome c reductase resolved in the sodium dodecyl sulfate-polyacrylamidce gel electrophoresis system of Schägger et al. (1987, FEBS Lett. 21, 161-168) and has the same amino acid sequence as that of the Mr 13,400 protein reported by Wakabayashi et al. (1985, J. Biol. Chem. 260, 337-343). The phospholipid and ubiquinone present in the preparation copurify with but are not intrinsic components of, the Mr 13,400 protein. This preparation has a potency and behavior identical to that of a free phospholipid preparation in restoring activity to delipidated ubiquinol-cytochrome c reductase. Antibodies against Mr 13,400 react only with Mr 13,400 protein and complexes which contain it. They do not inhibit intact, lipid-sufficient ubiquinol-cytochrome c reductase. However, when delipidated ubiquinol-cytochrome c reductase is incubated with antibodies prior to reconstitution with phospholipid, a 55% decrease in the restoration activity is observed, indicating that the catalytic site-related epitopes of the Mr 13,400 protein are buried in the phospholipid environment. Antibodies against Mr 13,400 cause an increase of apparent Km for ubiquinol-2 in ubiquinol-cytochrome c reductase. When mitoplasts or submitochondrial particles are exposed to a horseradish peroxidase conjugate of the Fab' fragment of anti-Mr 13,400 antibodies, peroxidase activity is found mainly in the submitochondrial particles preparation; little activity is detected in mitoplasts. This suggests that the Mr 13,400 protein is extruded toward the matrix side of the membrane.

Amino Acid Sequence↗
PubMed1991

[An inexpensive and flexible personal-computer-based system for controlling the multiple stimulus events in classical conditioning].

For the demand of biological discipline it is worth to develop a stimulus control system especially suitable for behavioral studies on learning and memory, in which the precise temporal control of the event sequence has been desired. We developed a flexible and inexpensive system based on IBM-PC for the classical conditioning of the marine mollusc. User can set a various temporal conditions with the data sheet on a display. It can be applicable in a wide range of conditions as well as in a lot of situations which require temporal control of multiple stimuli.

Animals↗
PubMed1991

An overview of biological signal processing: non-linear and non-stationary aspects.

The elucidation of biological systems will be one of great keys to scientific advance. However, it is difficult to analyze such biological systems because of their non-linear and non-stationary characteristics. This paper reviews newly developed methods for analysing such non-linear and non-stationary characteristics.

Neural Networks, Computer↗
PubMed1991

[A clinical evaluation of reconstruction methods after pancreatoduodenectomy from a view of fat digestion and absorption].

The purpose of this study was to evaluate the reconstruction methods of modified Imanaga procedure and modified Child procedure from a point of fat digestion and absorption in patients who received pancreatoduodenectomy by using 13C-labelled medium chain fat. The 13CO2 abundances were elevated rapidly after oral ingestion of 13C-octanoic acid and 13C-trioctanoin in modified Imanaga procedure group. The peak 13CO2 abundances appeared earlier in modified Imanaga procedure group than in modified Child procedure group. No significant difference was seen between two groups in the percent recovery of 13CO2 in the breath after oral loading of 13C-octanoic acid. But modified Imanaga procedure group showed significantly higher recovery rate of 13CO2 of 13C-trioctanoin when compared to modified Child procedure group. These results suggest that modified Imanaga procedure would have a benefit for fat digestion and absorption after pancreatoduodenectomy.

Aged↗
PubMed1990

The small molecular mass ubiquinone-binding protein (QPc-9.5 kDa) in mitochondrial ubiquinol-cytochrome c reductase: isolation, ubiquinone-binding domain, and immunoinhibition.

The small molecular mass ubiquinone-binding protein (QPc-9.5 kDa) was purified to homogeneity from 3-azido-2-methyl-5-methoxy-6-(3,7-dimethyl[3H]octyl)-1,4-benzoquinol+ ++- labeled bovine heart mitochondrial ubiquinol-cytochrome c reductase. The N-terminal amino acid sequence of the isolated protein is Gly-Arg-Gln-Phe-Gly-His-Leu-Thr-Arg-Val-Arg-His-, which is identical with that of a Mr = 9500 protein in the reductase [Borchart et al. (1986) FEBS Lett. 200, 81-86]. A ubiquinone-binding peptide was prepared from [3H]azidoubiquinol-labeled QPc-9.5 kDa protein by trypsin digestion followed by HPLC separation. The partial N-terminal amino acid sequence of this peptide, Val-Ala-Pro-Pro-Phe-Val-Ala-Phe-Tyr-Leu-, corresponds to amino acid residues 48-57 in the reported Mr = 9500 protein. According to the proposed structural model for the Mr = 9500 protein, the azido-Q-labeled peptide is located in the membrane on the matrix side. These results confirm our previous assessment that the Mr = 13,400 subunit is not the small molecular weight Q-binding protein. Purified antibodies against QPc-9.5 kDa have a high titer with isolated QPc-9.5 kDa protein and complexes that contain it. Although antibodies against QPc-9.5 kDa do not inhibit intact succinate- and ubiquinol-cytochrome c reductases, a decrease of 85% and 20% in restoration of succinate- and ubiquinol-cytochrome c reductases, respectively, is observed when delipidated succinate- or ubiquinol-cytochrome reductases are incubated with antibodies prior to reconstitution with ubiquinone and phospholipid, indicating that epitopes at the catalytic site of QPc-9.5 kDa are buried in the phospholipid environment.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1990

Cloning and sequencing of a cDNA encoding the Rieske iron-sulfur protein of bovine heart mitochondrial ubiquinol-cytochrome c reductase.

Two cDNA clones encoding bovine heart mitochondrial Rieske iron-sulfur protein were obtained by immunological screening of a bovine heart cDNA expression library in lambda gt11 with antiserum directed against Rieske iron-sulfur protein isolated from bovine heart mitochondrial ubiquinol-cytochrome c reductase. The cDNA inserts were 1005 and 1100 base pairs with an open reading frame of 807 base pairs which encoded a 196-amino acid mature Rieske iron-sulfur protein and a 73-amino acid presequence. The amino acid sequence of Rieske iron-sulfur protein deduced from nucleotide sequencing is the same as that obtained from protein sequencing except at residues #73 and #191 which are Ser and Asp instead of Ala and Gly, respectively.

Amino Acid Sequence↗
PubMed1990

Non-invasive automatic determination of anaerobic threshold using double gas exchange parameters.

A new technique for determining the anaerobic threshold (AT) in real-time during a progressive exercise test was proposed with special consideration to its safety. We applied the discriminant analysis based on the linear logistic regression model to two groups of gas exchange parameters at times just before and after the lactate (LA) threshold (determined by blood LA kinetics; the external criterion of AT) during the incremental exercise test in 21 young males. As a result, the selected variables for estimating AT accurately (the discriminant rate = 100%), were VE/VO2 and the relative change in VE. Our idea of the new technique for determining AT is based on the probability function (p(x)) derived from the discriminant analysis. At each time at which the gas exchange parameters are acquired during the exercise test, p(x) is calculated, and the decision whether the present exercise level is in the pre, just, or post-AT level is made by the p(x). The technique is able to stop the exercise test as quickly as possible after passing through the AT level. To evaluate the new technique, the data set of 66 females (aged 16-57) was applied as a form of simulation. It was shown that the exercise test could be stopped by the technique at a level of only 0.2-0.5 l/min in VO2 higher than AT. This advantage of the technique makes the exercise test safer for middle-aged or old men, and patients during cardiac rehabilitation.

Adolescent↗
PubMed1990

[Spontaneous saccades in MPTP-induced hemi-parkinsonian monkeys].

The basal ganglia play an important role in the control of saccadic eye movements. Parkinsonian patients have deficits in saccade initiation; the deficits are more prominent in memory-guided saccade than in visually guided saccade (Hikosaka et al, 1987). These results show that deficiency of nigrostriatal dopaminergic system affects the neural mechanism of saccadic eye movements in the basal ganglia. In order to investigate this hypothesis, we studied saccadic eye movements in MPTP-induced hemiparkinsonian monkeys. We made two models of parkinsonism using two monkeys: 1) unilateral intra-carotid injection of MPTP, and 2) intracaudate injection of MPTP using osmotic minipump. We recorded saccadic eye movements using the magnetic search coil method. After experiments, monkeys were sacrificed and investigated by histological procedures. Following the intracarotid injection, we observed hypokinesia and rigidity in the arm and leg contralateral to the injection. Eye position was shifted to the ipsilateral side and the frequency of saccades towards the contralateral side was reduced. Following the intracaudate injection, we observed hypokinesia and rigidity in the contralateral arm and leg and circling behavior towards the contralateral side. In both monkeys, the saccade amplitude and peak velocity towards contralateral side were reduced. We considered three mechanisms that might account for these results. First, dopaminergic denervation due to MPTP in the caudate nucleus may suppress the activity of neurons projecting to the pars reticulata of the substantia nigra. Second, nigra cell activity may be tonically elevated through an indirect pathway via the external pallidum and the subthalamic nucleus. Third, MPTP may enhance nigra cell activity through dendro-dendritic connections from the pars compacta to the pars reticulata in the substantia nigra.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗