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Biomedical subjects

Y Emoto

Publications and source records attributed to Y Emoto.

At least 55 records · Page 3Linked to original sources
PubMed1993

Inhibition of mitochondrial respiration by furancarboxylic acid accumulated in uremic serum in its albumin-bound and non-dialyzable form.

3-carboxy-4-methyl-5-propyl-2-furanpropionic acid (CMPF) accumulates markedly in uremic serum in its albumin-bound form. To determine if CMPF can be removed by newly developed dialyzers with high-flux membranes which are permeable to low-molecular-weight proteins, such as beta 2-microglobulin (beta 2-MG), serum levels of CMPF were determined before and after hemodialysis using these high-flux membrane dialyzers. In addition, to determine the pathogenic role of CMPF in uremic patients, its cellular toxicity due to its effect on mitochondrial respiration was studied. The reduction rates of CMPF by hemodialysis using the dialyzers ranged from -17% to -24%, demonstrating the nondialyzability of CMPF due to its strong albumin-binding, while those of beta 2-MG ranged from 11% to 43%. CMPF inhibited ADP-stimulated oxidation of NADH-linked substrates in isolated mitochondria dose-dependently regardless of the presence of serum albumin. This inhibition was observed even at a concentration of 0.2 mM, which is comparable to the serum levels of CMPF in the hemodialysis patients. In conclusion CMPF which cannot be removed even by high-flux membrane dialyzers, is a strong inhibitor of mitochondrial respiration, and novel purification methods to remove CMPF from the blood of uremic patients should be developed.

Animals↗
PubMed1992

Purification and characterization of a new member of the S-100 protein family from human placenta.

A novel Ca(2+)-binding protein which is termed S-100P was purified from human placenta with a hydrophobic column followed by an anion exchange column and reverse phase high performance liquid chromatography (HPLC). Molecular mass of the protein was 10 kDa according to sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis. Using immunoblotting technique, anti-human calcyclin antibodies did not bind to the S-100P. Isoelectric point of S-100P was pI = 4.6. S-100P did not formed disulfide-linked dimer. Calcium binding ability was proved by UV difference spectrometry, urea/alkaline gel electrophoresis, and 45Ca overlay technique. A ninety amino acid sequence of S-100P was determined. It is 49% identical with human S-100 beta, 38% with human calcyclin, and 37% with human cystic fibrosis antigen.

Amino Acid Sequence↗
PubMed1991

Oral sorbent suppresses accumulation of albumin-bound indoxyl sulphate in serum of haemodialysis patients.

Serum indoxyl sulphate, which is markedly accumulated in haemodialysis patients, cannot be removed efficiently by haemodialysis due to its albumin-binding property. To determine whether an oral adsorbent (AST-120) can decrease its serum concentration, AST-120 was administered to haemodialysis patients. The patients given AST-120 showed significantly reduced serum concentration of indoxyl sulphate as compared to control haemodialysis patients, even though the serum concentrations of urea nitrogen and creatinine did not decrease significantly in the patients treated with AST-120. The haemodialysis patients with generalised pruritus showed an amelioration of itching after administration of AST-120. These results showed that AST-120 was effective in reducing the serum concentration of albumin-bound indoxyl sulphate in haemodialysis patients by adsorption of indole, a precursor of indoxyl sulphate, in the intestines, and that it relieved itching in haemodialysis patients with generalised pruritus.

Administration, Oral↗
PubMed1991

A case of lupus nephritis showing rectal erosion with cytomegalovirus infection.

A case of lupus nephritis showing rectal erosion with cytomegalovirus infection is described. The patient revealed nephrotic syndrome. She complained of skin ulcer with livedo reticularis on the right breast, purpura with thrombocytopenia, hepatic dysfunction, and bloody stool. Renal biopsy demonstrated diffuse proliferative lupus nephritis with prominent wire loops. Intestinal fiberscopy showed rectal erosion which was a cause of bloody stool, and rectal biopsy revealed cytomegalic inclusions characteristic of cytomegalovirus infection. Immunosuppression due to combined therapy with prednisolone and mizoribine could have led to reactivation of latent cytomegalovirus infection, resulting in the rectal erosion with bloody stool.

Adult↗
PubMed1991

Accumulation of quinolinic acid in uremic serum and its removal by hemodialysis.

Quinolinic acid was first identified in uremic serum by use of gas chromatography/mass spectrometry. Quantification by selected ion monitoring revealed that the serum concentration of quinolinic acid was markedly increased in chronic hemodialysis patients, and that the acid could be removed by conventional hemodialysis. The serum concentration of quinolinic acid was weakly but significantly correlated with the serum uric acid concentration. Accumulation of quinolinic acid in uremic blood may be involved in the pathogenesis of anemia, suppressed immune system, and uremic encephalopathy.

Adult↗
PubMed1990

Effectiveness of push/pull hemodiafiltration using large-pore membrane for shoulder joint pain in long-term dialysis patients.

Long-term hemodialysis (HD) patients complaining of shoulder joint pain were treated by HD and by push/pull HDF using high-flux synthetic membranes with large pores (Asahi PAN 20CX2) for 2 weeks. The results showed no significant difference in Kt/Vurea between HD and push/pull HDF. Nevertheless, reduction of the plasma beta 2-microglobulin was greater during push/pull HDF than during HD. These findings can be explained by far more convective flux in push/pull HDF than in HD: nearly 30 L during push/pull HDF vs. 3 L during HD. In the present study, there was no alleviation of the shoulder joint pain during HD treatment, whereas marked relief of the symptom was found during push/pull HDF treatment. Since the two treatment modalities differ simply in their efficiency in removing larger molecular weight substances, the joint pain alleviation effected by push/pull HDF could well be ascribed to elimination of an unknown larger molecular weight substance causing this symptom. However, a considerable amount of beta 2-microglobulin was removed both by HD and push/pull HDF. Therefore, the substance causing the joint pain might be larger than beta 2-microglobulin.

Female↗
PubMed1988

Separation of SH-modified myosin subfragment-1 (A1) isozyme into two distinct equimolar fractions by an affinity chromatography.

Our previous kinetic studies indicated that SH-modified myosin subfragment-1 A1 isozyme (S1(A1] contains at least two different types of active sites (Emoto, Y., Kawamura, T., & Tawada, K. (1985) J. Biochem. 98, 735-745). In those studies we have modified highly reactive SH-groups in S1(A1) with thimerosal. In this work, we separated the modified S1(A1) into two equimolar fractions by affinity chromatography with agarose-ADP. For the separation, Mg2+ in the elution buffer was indispensable. Although the two fractions appeared to have the same number of modified SH-groups per mol of S1, they had different enzymic and fluorescent properties. SH-modification with an excess of thimerosal for a much longer duration did not change any of the results: not the chromatographic profile, the properties of the two fractions, nor the number of modified SH-groups. Hence the two different populations were not generated by incomplete modification. After reduction with dithiothreitol, however, the differences between the two fractions disappeared. When we separately re-modified the reduced fractions and re-chromatographed them, in each case we again obtained two fractions, which had the same properties as the two fractions obtained from the original modification with thimerosal. These results demonstrate that the active site heterogeneity in SH-modified S1(A1) had no intrinsic origin in the unmodified S1: it was introduced by the SH-modification, but by an unknown mechanism(s) other than incomplete modification.

Adenosine Triphosphatases↗
PubMed1988

Rigor tension development in glycerinated rabbit psoas fibers at high salt concentrations.

We attempted to measure the rigor tension development by glycerinated fibers of rabbit psoas at high salt concentrations such as 0.5 M KCl. The measurements were made feasible by covalently crosslinking the rod-portion of thick filaments in the fibers in the rigor state with a water-soluble carbodiimide (EDC) so that the thick filaments are not dissolved even at 0.5 M KCl. EDC crosslinks, though with much a slower rate, the myosin cross-bridge heads to the thin filaments. At high salt concentrations, the fibers developed no active tension but developed rigor tension when they were put into a rigor solution from a contracting or relaxing solution. Removal of only Mg++ from a MgATP-containing solution induced similar rigor tension development. The magnitude of the rigor tension was proportional to the fraction of the cross-bridge heads that were crosslinked to the thin filaments. The results suggest that the rigor tension at high salt concentrations is generated by structural changes in the cross-bridge heads that are crosslinked to the thin filaments, when these heads release MgATP or Mg++ (with ATP retained) from their active sites, but not generated by re-formation of the rigor complexes of uncrosslinked myosin heads with the thin filaments. Extrapolation to 100% crosslinked heads gave an estimate of the rigor tension development of more than 1 kg wt/cm2 at high salt concentrations.

Actin Cytoskeleton↗
PubMed1985

Relationship between the ATPase activity and the ATP-induced fluorescence enhancement of SH-modified heavy meromyosin during its fractional inactivation by vanadate plus ADP: evidence for heterogeneity in the active sites.

We have examined whether heavy meromyosin (HMM) consists of a single kind of active site by analyzing the changes in the relative MgATPase activity and the relative amplitude of the ATP-induced fluorescence enhancement of the protein when the fraction of HMM "affinity"-labeled by vanadate plus ADP was varied. The analysis is based on a prediction that these two changes should be proportional to each other if myosin consists of a single kind of active site and generates the rate-limiting myosin**product complex emitting enhanced fluorescence. Although the difference between these two changes was very small with native HMM, it was large with HMM in which 5 fast-reactive sulfhydryl-groups per head were pre-modified with thimerosal. The difference indicated the existence of heterogeneous active sites in the SH-modified HMM. The results were best explained in terms of the hypothesis that fifty percent of the active site splits MgATP by a mechanism giving a fluorescence enhancement whereas the other fifty percent splits MgATP by another mechanism giving no fluorescence enhancement. Two possible explanations for the existence of heterogeneous active sites in the SH-modified HMM are discussed. One assumes the pre-existence of some sort of 1:1 heterogeneity in the micro-environment of the active sites and the other, which is considered less likely, assumes the introduction of the heterogeneity as a result of the SH-modification.

Actins↗
PubMed1985

Characterization of the ATPase active site in myosin subfragment-1 with the use of vanadate plus ADP as a reversible "affinity-labeling" reagent: evidence for heterogeneity in the active sites.

Our previous work showed that the active site heterogeneity in heavy meromyosin (HMM) becomes evident when highly reactive SH-groups in HMM are modified by thimerosal (Kawamura, Higuchi, Emoto, & Tawada (1985) J. Biochem. 97, 1583-1593). The heterogeneity was revealed by "affinity-labeling" analysis with vanadate plus ADP, which was developed in the previous paper. To see whether this heterogeneity is due to the head-head interaction or two different alkali light chains present in HMM, we carried out similar studies with myosin subfragment-1 (S1) and one of the isozymes, S1(A1), which contains only the alkali light chain 1, and obtained essentially the same results as those previously obtained with HMM. The S1 results are easily explained by the same hypothesis previously used for explaining the HMM results: SH-modified S1 or S1(A1) contains two kinds of active site in a 1:1 ratio with almost the same ATPase activity: one hydrolyzes ATP by a mechanism giving a protein Trp fluorescence enhancement, whereas the other hydrolyzes ATP by another mechanism giving no fluorescence enhancement.

Adenosine Triphosphatases↗