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Satoru Ueno

Publications and source records attributed to Satoru Ueno.

25 records · Page 2Linked to original sources
PubMed2004

Effects of static load on the weight and protein content in the leg muscles of the mouse: a simulation of prolonged standing in the workplace.

To simulate the effects of prolonged standing in the workplace on the leg muscles, we subjected mice to centrifugation for 6 wk. The absolute wet weight of leg muscles and internal organs of mice were measured after exposure to 3G by centrifugation for 6 wk and at 2 wk after removal of centrifugation. The weight of the soleus muscle (antigravity muscle) significantly increased after 6-wk exposure to centrifugation, but it decreased to its control weight 2 wk after removal of centrifugation. In contrast, the wet weights of the anterior tibial muscle, liver, and kidneys of mice centrifuged for 6 wk were significantly lower than those of the control mice; they had returned to control levels 2 wk after removal of centrifugation. It was therefore suggested that prolonged standing enlarged the leg muscles but its effect did not last for a long period of time after stopping prolonged standing. Western blot analysis of proteins extracted from the soleus muscle showed that vinculin and alpha-actinin in the centrifuged mice increased slightly, but there were no differences in the heat shock protein 70 (HSP70) and desmin levels between the centrifuged mice and control mice. No difference in HSP 70 suggested that muscle damage did not exist after 6 wk centrifugation.

Animal Experimentation↗
PubMed2003

Synthetic copoly(Lys/Phe) and poly(Lys) translocate through lipid bilayer membranes.

Several membrane-transporting peptides (MTP) containing basic amino acid residues such as Lys and Arg that carry macromolecules such as DNA and proteins across cell plasma membranes by an unknown mechanism have been actively studied. On the basis of these results, we have been investigating the translocation ability of synthetic polypeptides, copoly(Lys/Phe) and poly(Lys), through negatively charged phospholipid (soybean phospholipid (SBPL)) bilayer membranes by zeta potential analysis, circular dichroism (CD) spectroscopy, fluorescence spectroscopy, an electrophysiology technique, and confocal laser scanning microscopy (CLSM). The binding of these polypeptides to the membrane, which is the first step for translocation across the membrane, resulted in the conformational transition of the polypeptide from a random coil form or helix-poor form to a helix-rich form. The fluorescence studies demonstrated that the time-dependent decrease in the fluorescence intensities of the FITC-labeled polypeptides bound to the SBPL liposome reflected translocation of the polypeptide across the lipid bilayer with the low dielectric constant. Both the rate constant and the efficiency of the polypeptide translocation across the lipid bilayer were greater for copoly(Lys/Phe) than for poly(Lys). These results suggest that the random incorporation of the hydrophobic Phe residue into the positively charged Lys chain results in a lowering of the potential barrier for passage of the polypeptide in the hydrophobic core portion of the lipid bilayer. We presented the first direct observation that the positively charged polypeptides, copoly(Lys/Phe) (MW: 41,500) and poly(Lys) (MW: 23,400), could translocate across the lipid bilayer membrane.

Adsorption↗
PubMed2003

Redox potentials of the oriented film of the wild-type, the E194Q-, E204Q- and D96N-mutated bacteriorhodopsins.

The redox potentials of the oriented films of the wild-type, the E194Q-, E204Q- and D96N-mutated bacteriorhodopsins (bR), prepared by adsorbing purple membrane (PM) sheets or its mutant on a Pt electrode, have been examined. The redox potentials (V) of the wild-type bR were -470 mV for the 13-cis configuration of the retinal Shiff base in bR and -757 mV for the all-trans configuration in H(2)O, and -433 mV for the 13-cis configuration and -742 mV for the all-trans configuration in D(2)O. The solvent isotope effect (DeltaV=V(D(2)O)-V(H(2)O)), which shifts the redox potential to a higher value, originates from the cooperative rearrangements of the extensively hydrogen-bonded water molecules around the protonated C=N part in the retinal Schiff base. The redox potential of bR was much higher for the 13-cis configuration than that for the all-trans configuration. The redox potentials for the E194Q mutant in the extracellular region were -507 mV for the 13-cis configuration and -788 mV for the all-trans configuration; and for the E204Q mutant they were -491 mV for the 13-cis configuration and -769 mV for the all-trans configuration. Replacement of the Glu(194) or Glu(204) residues by Gln weakened the electron withdrawing interaction to the protonated C=N bond in the retinal Schiff base. The E204 residue is less linked with the hydrogen-bonded network of the proton release pathway compared with E194. The redox potentials of the D96N mutant in the cytoplasmic region were -471 mV for the 13-cis configuration and -760 mV for the all-trans configuration which were virtually the same as those of the wild-type bR, indicating that the D to N point mutation of the 96 residue had no influence on the interaction between the D96 residue and the C=N part in the Schiff base under the light-adapted condition. The results suggest that the redox potential of bR is closely correlated to the hydrogen-bonded network spanning from the retinal Schiff base to the extracellular surface of bR in the proton transfer pathway.

Bacteriorhodopsins↗
PubMed2003

Associations between oxidative stress levels and total duration of engagement in jobs with exposure to fly ash among workers at municipal solid waste incinerators.

The fly ash from municipal solid waste incinerators (MSWIs) is known to contain heavy metals, polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polyaromatic hydrocarbons (PAHs), and other organic materials. Heavy metals, PCDDs, PCDFs and PAHs reportedly cause oxidative stress in vitro and in vivo. In this study, we have measured the blood and urinary levels of several oxidative stress markers in MSWI workers and discuss herein whether the duration of engagement in jobs with exposure to MSWI fly ash is associated with these levels. The subjects were 81 male workers (mean age 42.7 years) from four MSWIs in the same city. Job history was determined from each subject and jobs were categorized according to the possibility of exposure to fly ash. The subjects were classified into four groups: long duration of engagement in jobs with exposure to fly ash, short duration of engagement in jobs with exposure to fly ash, engagement in jobs with limited exposure to fly ash and control. Blood and urine specimens were obtained from the subjects in the morning before breakfast. The levels of 8-hydroxy-2'-deoxyguanosine (8-OH-dG) in the urine and leukocytes were measured as markers of oxidative DNA damage. Blood malondialdehyde and lipid peroxide levels and the level of total urinary biopyrrins were also measured as markers of systemic oxidative stress. The mean levels of all markers were compared among the four groups. There was a significant trend showing that the level of urinary 8-OH-dG rose with increased duration of engagement in jobs with exposure to MSWI fly ash (P<0.05). Considering this result, we speculate that certain chemicals in fly ash might have induced oxidative stress in the study subjects.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2002

Case of mediastinal seminoma with testicular microlithiasis.

Testicular microlithiasis is a rare condition in which calcified concretions fill the lumina of the seminiferous tubules. We report the case of a 19-year-old Japanese man with mediastinal seminoma, normal testicular physical findings and bilateral testicular microlithiasis seen on ultrasonography. Testicular needle biopsy demonstrated multiple laminated calcifications within the seminiferous tubules without any signals of a viable germ cell tumor. To our knowledge, this is only the sixth reported case of extragonadal germ cell tumor with testicular microlithiasis.

Adult↗
PubMed2002

Effects of pH and temperature on force and stiffness of skeletal muscle fibers during contraction and relaxation in relation to musculoskeletal disorders.

Effects of low pH (6.0, 6.5) were studied at three temperatures (5, 15, 25 degrees C) on the isometric force and stiffness of glycerinated muscle fibers dissected from soleus (type I) and psoas (type IIX) muscles of the Japanese white rabbit. It was observed that the maximum force and stiffness declined as pH decreased, the extent of which was diminished by an increase in temperature in both muscle types. The pH-induced changes in force were greater than those in the stiffness for both muscle types: at 5 degrees C, the psoas showed greater change in stiffness than the soleus. As the pH of the contracting solution decreased, the time to peak stiffness decreased and the time to relaxation increased in both muscle types. At pH 6.0, the latter was significantly longer than the former. The force-stiffness curves indicated that, when pH decreased, force increased as fast as stiffness during contraction and force declined faster than stiffness during relaxation. The results suggested that one of the causes of muscle injury during hard muscular work could be the longer relaxation time in an acidic solution.

Animals↗