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Biomedical subjects

M Yoshida

Publications and source records attributed to M Yoshida.

At least 1,063 records · Page 59Linked to original sources
PubMed1997

Cerebral complications and distal false lumen in the repair of aortic dissection with retrograde cerebral perfusion.

BACKGROUND: In aortic dissection, patent distal false lumen at long-term follow-up leads to complications. We investigated the feasibility of an open distal anastomosis under retrograde cerebral perfusion. METHODS: During a 15-year period (1981-1995), 51 patients with type A dissection underwent 59 surgical repairs. In 1990, a distal open anastomosis with retrograde cerebral perfusion (group II) was introduced to replace the aortic cross clamp method (group I). Mean retrograde cerebral perfusion time was 50 minutes (range 22 to 65 minutes) with no neurologic sequelae in surviving patients. RESULTS: Operative mortality was 28.6% in group I, and 16.1% in group II. At long-term follow-up, dilatation of the false lumen (more than 50 mm in diameter) occurred in 56.2% (9/16) in group I, and 4 patients died of aortic rupture. There was no mortality in group II, and dilatation of the distal false lumen occurred in only 15.3% (p<0.05). CONCLUSIONS: Use of retrograde cerebral perfusion in aortic dissection allowed for adequate time to perform a safe, open, distal anastomosis. Intraoperative cerebral complications and enlarged patent false lumens decreased significantly.

Acute Disease↗
PubMed1997

Italo-Canadian mothers' beliefs surrounding cause and treatment/cure of childhood disabilities.

A qualitative design was used to explore Italo-Canadian beliefs about the cause and treatment/cure of childhood disabilities. A convenience sample of eight second-generation Italo-Canadian mothers of children with moderate to severe disabilities was recruited through a pediatric rehabilitation centre in Southern Ontario. The mothers were interviewed using open-ended questions that served as probes to stimulate their thoughts and feelings. Data analysis proceeded concomitantly with data collection, and consisted of content analysis. Three major categories of traditional causation beliefs were identified: (a) punishment for past wrongdoing, (b) "bad blood" caused by intermarriage or a family curse, and (c) supernatural forces such as mal'occhio (the evil eye). The major category identified for cure of childhood disability was magico-religious healing. These traditional beliefs were described by the mothers to be strongest among first-generation Italo-Canadians, especially grandparents. The mothers themselves expressed their acceptance of some of these beliefs, but only minimal acceptance of or resistance to others. Based on this study, it would be premature to formulate implications for practice; however, several directions for future research are identified.

Adult↗
PubMed1997

[A case of amyloidosis of the tracheobronchial tree and inferior nasal concha].

A 50-year-old man resented at a local medical clinic with nasal obstruction. He was treated but did not improve. He then consulted our institution. Chest X-ray disclosed infiltrative shadows in the basal region of the left lung. A computed tomography scan of the lung showed marked thickening of the airway walls extending from the trachea to both bronchial trees and obstructive changes in the left lower lobe of the lung. On bronchoscopic examination the bronchial mucosa was reddened and edematous with a pinhole bronchial obstruction in one region. Congo red staining of biopsy samples taken from the bronchial mucosa showed deposition of an amorphous substance. Tracheobronchial amyloidosis was diagnosed. The amyloid material was resistant to potassium permanganate and tested positive for lambda-chain of L immunoglobulin. Otorrhinolaryngological examination disclosed a tumor in the inferior nasal concha as the cause of his nasal obstruction. The nasal tumor was resected and AL lambda-type amyloidosis was diagnosed pathologically. Tracheobronchial and inferior nasal concha amyloidosis is an extremely rare pathological condition. The patient was followed for one year and remain asymptomatic without treatment.

Amyloidosis↗
PubMed1996

Purification and identification of a 28-kDa calcium-regulated heat-stable protein. A novel secretagogue-regulated phosphoprotein in exocrine pancreas.

This study reports the purification and identification of a novel 28 kDa phosphoprotein from rat pancreatic acini, previously described as being highly regulated by calcium mobilizing secretagogues, which we have designated calcium-regulated heat-stable protein 28 (CRHSP-28). Internal amino acid sequences of purified CRHSP-28 were obtained following trypsin digestion and found to match with >95% identity the predicted amino acid sequence of a novel cDNA recently identified as being highly expressed in human breast carcinomas. Verification that this cDNA codes for human CRHSP-28 was demonstrated by the ability of antiserum raised against purified rat CRHSP-28 to recognize the recombinant human protein when expressed in bacteria. Furthermore, this antibody was found to specifically react with CRHSP-28 in rat acini following one- and two-dimensional electrophoresis and underwent a marked acidic shift in mobility after cholecystokinin stimulation, a phenomenon indicative of an increase in its phosphorylation. CRHSP-28 is predicted to be extremely hydrophilic, is phosphorylated entirely on serine residues, and bears little homology to any known proteins. Finally, the distribution of the CRHSP-28 protein in various rat tissues revealed that although it was present at low levels in almost all tissues, it was most highly expressed in pancreas, followed by the gastric, intestinal, and colonic mucosa. In view of its relative abundance throughout the digestive system and its apparent regulation by calcium-mobilizing agents, this protein may provide valuable insight into the mechanism(s) of calcium signaling in these tissues.

Amino Acid Sequence↗
PubMed1996

Interferon-gamma induces Ice gene expression and enhances cellular susceptibility to apoptosis in the U937 leukemia cell line.

The roles of interferons (IFNs) in apoptosis are not fully understood. In this study we show that in the U937 monoblastic leukemia cell line, pretreatment with IFN-gamma enhanced sensitivity to apoptosis triggered by gamma-irradiation or antitumor agents (etoposide or adriamycin), as well as by anti-Fas antibody. In addition, IFN-gamma caused an increased expression of the interleukin-1 beta-converting enzyme (Ice) gene, following strong induction of the interferon regulatory factor-1 (IRF-1) gene, the product of which is a transcriptional activator of the Ice gene. An inhibitor of ICE/Ced-3 family proteases, Z-Asp-CH2-DCB, blocked apoptosis in control cells as well as in IFN-gamma-pretreated cells. These results suggest that enhanced susceptibility of IFN-gamma-pretreated cells to apoptosis is mediated through the induction of Ice by IRF-1. This pathway is not affected by interleukin-1 beta (IL-1 beta) since neutralizing antibody against IL-1 beta failed to suppress the IFN-gamma-mediated enhancement of cell death, and IL-1 beta itself did not mimic the effect of IFN-gamma.

Antibiotics, Antineoplastic↗
PubMed1996

The alpha3beta3gamma subcomplex of the F1-ATPase from the thermophilic bacillus PS3 with the betaT165S substitution does not entrap inhibitory MgADP in a catalytic site during turnover.

The hydrolytic properties of the mutant alpha3(betaT165S)3gamma and wild-type alpha3beta3gamma subcomplexes of TF1 have been compared. Whereas the wild-type complex hydrolyzes 50 microM ATP in three kinetic phases, the mutant complex hydrolyzes 50 microM ATP with a linear rate. After incubation with a slight excess of ADP in the presence of Mg2+, the wild-type complex hydrolyzes 2 mM ATP with a long lag. In contrast, prior incubation of the mutant complex under these conditions does not affect the kinetics of ATP hydrolysis. The ATPase activity of the wild-type complex is stimulated 4-fold by 0. 1% lauryl dimethylamine oxide, whereas this concentration of lauryl dimethylamine oxide inhibits the mutant complex by 25%. Compared with the wild-type complex, the activity of the mutant complex is much less sensitive to turnover-dependent inhibition by azide. This comparison suggests that the mutant complex does not entrap substantial inhibitory MgADP in a catalytic site during turnover, which is supported by the following observations. ATP hydrolysis catalyzed by the wild-type complex is progressively inhibited by increasing concentrations of Mg2+ in the assay medium, whereas the mutant complex is insensitive to increasing concentrations of Mg2+. A Lineweaver-Burk plot constructed from rates of hydrolysis of 20-2000 microM ATP by the wild-type complex is biphasic, exhibiting apparent Km values of 30 microM and 470 microM with corresponding kcat values of 26 and 77 s-1. In contrast, a Lineweaver-Burk plot for the mutant complex is linear in this range of ATP concentration, displaying a Km of 133 microM and a kcat of 360 s-1.

Adenosine Diphosphate↗
PubMed1996

Unusual pKa of the carboxylate at the putative catalytic position of the thermophilic F1-ATPase beta subunit determined by 13C-NMR.

Glutamic acid-190 in the beta subunit of F1-ATPase from thermophilic Bacillus PS-3 (TF1) was reported to be essential for the ATPase activity. The mutant TF1beta subunit in which Glu-190 had been substituted by cysteine was carboxymethylated with 13C-labeled monoiodoacetic acid. The pKa value of the carboxymethylene group at the 190 position was determined as 5.6 +/- 0.4 by 13C-NMR. On the basis of this value, the pKa of the carboxylate of Glu-190 of the TF1beta subunit was estimated to be 6.8 +/- 0.5. The unusually high pKa could play a role in the catalytic mechanism of F1-ATPase.

Adenosine Diphosphate↗
PubMed1996

GroEL locked in a closed conformation by an interdomain cross-link can bind ATP and polypeptide but cannot process further reaction steps.

It has been believed that when GroEL binds to GroES its apical domain moves upward and outward. To inhibit this "opening" movement, its equatorial and apical domains were cross-linked through a disulfide bond between mutationally introduced cysteine residues at the positions of Asp-83 and Lys-327. To avoid possible undesired cross-linking, we at first prepared a mutant GroEL (GroELNC; Cys-138 --> Ser, Cys-458 --> Ser, Cys-519 --> Ser) in which all cysteine residues in wild-type GroEL were replaced by serine residues. GroELNC was fully functional as a chaperonin. We then introduced the above two point mutations into GroELNC to generate a mutant (GroELAEX; Cys-138 --> Ser, Cys-458 --> Ser, Cys-519 --> Ser and Asp-83 --> Cys, Lys-327 --> Cys). Oxidized GroELAEX, which is locked in a "closed" conformation by an interdomain disulfide bond, can bind 6-7 mol of ATP, which remain bound without hydrolysis. This ATP-bound, oxidized GroELAEX can bind the stably nonnative substrate protein isopropylmalate dehydrogenase, whereas the nucleotide-free oxidized GroELAEX binds it with a weaker affinity. However, oxidized GroELAEX fails to process further reaction steps such as ATP hydrolysis, binding of GroES, dissociation of substrate protein from GroEL, and facilitating protein folding. When disulfide bonds in oxidized GroELAEX are reduced, GroELAEX exerts the ability to process all the reactions just as GroELNC and wild-type GroEL. Indications from these results are: hydrolysis of ATP may require opening movement of the apical domain; GroES binds to an open form of GroEL; and substrate polypeptide is released from GroEL coupled with either ATP hydrolysis or opening movement of the apical domain.

3-Isopropylmalate Dehydrogenase↗
PubMed1996

Chronic administration of 1-benzyl-1,2,3,4-tetrahydroisoquinoline, an endogenous amine in the brain, induces parkinsonism in a primate.

1-Benzyl-1,2,3,4-tetrahydroisoquinoline hydrochloride (1Bn TIQHCl) (22 mg/kg per day) was subcutaneously injected into a monkey, Macaca fascicularis for 66 days to investigate its acute and chronic effects Parkinsonism like motor symptoms appeared, and the acute toxicity was stronger than the chronic toxicity. This result suggested that 1BnTIQ may induce parkinsonism in humans. 1BnTIQ content in various regions of the monkey brain was determine by the gas chromatography-selected ion-monitoring method, but no significant variation was found.

Animals↗
PubMed1996

Analysis of interleukin 6 receptor and gp130 expressions and proliferative capability of human CD34+ cells.

We recently demonstrated that stimulation of gp130 by a combination of soluble interleukin 6 receptor (sIL-6R) and IL-6 but not IL-6 alone significantly stimulates the ex vivo expansion of primitive hematopoietic progenitors and the generation of erythroid cells from human CD34+ cells in the presence of stem cell factor (SCF). Here, we show that gp130 is found low positively on most CD34+ cells, whereas IL-6R is expressed on only 30-50% of these cells. Although most of the colonies generated from FACS-sorted CD34+IL-6R+ cells were granulocyte/macrophage (GM) colonies, CD34+IL-6R- cells gave rise to various types of colonies, including erythroid bursts, GM, megakaryocytes, and mixed colonies in methylcellulose culture with a combination of IL-6, sIL-6R, and SCF. Similar results were obtained in culture supplemented with a combination of IL-3, IL-6, SCF, granulocyte colony-stimulating factor, erythropoietin, and thrombopoietin. A limiting dilution analysis of long-term culture-initiating cells (LTC-IC) showed that the CD34+IL-6R- cells contained a larger number of LTC-IC than did the CD34+IL-6R+ cells. In a serum-free suspension of CD34+IL-6R- cells, the addition of sIL-6R to the combination of IL-6 and SCF dramatically increased the total and multipotential progenitors, whereas CD34+IL-6R+ cells failed to do so under the same conditions. These results indicate that most of the erythroid, megakaryocytic, and primitive human hematopoietic progenitors are included in the IL-6R- populations, and the activation of gp130 on these progenitors can be achieved by a complex of IL-6-sIL-6R, but not by IL-6 alone. The present culture system using IL-6, sIL-6R, and SCF may provide a novel approach for ex vivo expansion of human primitive hematopoietic progenitors.

Adult↗
PubMed1996

Expression of thymopoietin beta/lamina-associated polypeptide 2 (TP beta/LAP2) and its family proteins as revealed by specific antibody induced against recombinant human thymopoietin.

An expression vector was constructed to produce a common region of human thymopoietin family proteins. The recombinant protein was expressed in Escherichia coli as a fusion protein with a biotinylated tag region and purified by affinity chromatography on a monomeric avidin resin. The thymopoietin family-specific antibody was induced in rabbits by immunization with the recombinant fusion protein. Western blotting analysis using the antibody revealed that the expression of thymopoietin family proteins was remarkably tissue specific. Among those, thymopoietin beta/lamina-associated polypeptide 2 appears to be specifically expressed in tissues with high proliferative activity.

Amino Acid Sequence↗
PubMed1996

Localization of the specific binding site for magnesium(II) ions in factor IX.

We demonstrated recently that coagulation factor IX has a specific binding site(s) for Mg2+ ions, independent of the (Ca2+)-binding sites, and that binding of Mg2+ ions is very important for expression of the functional conformation of this protein. We report here the localization of this Mg2+-specific binding site. We prepared three Gla-containing fragments of bovine factor IX, namely GlaEGF(NC) (residues 1-144+286-296), GlaEGF(N) (1-83) and the Gla domain peptide (1-46). Fragments GlaEGF(NC) and GlaEGF(N) retained the ability to undergo a conformational change upon binding of Mg2+ ions in the presence of excess Ca2+ ions. This change could be detected by a conformation-specific antibody. Furthermore, the Gla domain peptide was capable of binding Mg2+ ions, as determined by the metal ion-induced quenching of the intrinsic fluorescence. It appears that the (Mg2+)-specific binding site of factor IX is located in the N-terminal Gla domain.

Amino Acid Sequence↗
PubMed1996

Calcium-dependent potentiation of M-current in bullfrog sympathetic neurons.

Whole-cell voltage-clamp recordings were made from cultured bullfrog sympathetic neurons to measure the steady-state activation curve of M-type potassium current. When measured with a calcium-deficient (10 nM) pipette solution M-conductance was 4.8 nS at -35 mV having the 50%-activation voltage at-20 mV. Respective values were 17.2 nS at -35 mV with the 50%-activation voltage at -42 mV when measured with a calcium-rich (1 microM) solution, indicating the hyperpolarizing displacement of the activation curve with high internal calcium. It is suggested that intracellular calcium ions can modulate kinetics of M-current which thereby regulate the number of M-channels being open at given membrane potentials.

Animals↗
PubMed1996

Catalytic activities of alpha3beta3gamma complexes of F1-ATPase with 1, 2, or 3 incompetent catalytic sites.

In order to know how many functional catalytic sites are necessary for ATPase activity of F1-ATPase from a thermophilic Bacillus PS3, a new method of isolating homogeneous preparations of the alpha3beta3gamma complex with 1, 2, or 3 incompetent catalytic sites was developed. Ten glutamic acids (Glu.Tag) were linked to the C terminus of the catalytically incompetent beta(E190Q) subunit. The Glu.Tag itself did not affect ATPase activity of the complexes. Two kinds of alpha3beta3gamma complexes, one containing beta(wild-type) and the other Glu.Tag-linked beta(E190Q), were mixed, urea-denatured, and dialyzed, and alpha3beta3gamma complexes were reconstituted. Each of the complexes containing a different number of Glu.Tag-linked beta(E190Q) was separated by anion-exchange chromatography and analyzed. The results were as follows. 1) Normal steady-state ATPase activity requires three intact catalytic sites. 2) Chase-acceleration, a catalytic cooperativity, requires at least two intact catalytic sites. 3) Single-site catalysis can be mediated by a single intact catalytic site alone. Rescrambling of subunits between complexes could occur when the complex was aged under certain conditions, and this might be one of the reasons for previous contradictory results (Miwa, K., Ohtsubo, M., Denda, K., Hisabori, T., Date, T., and Yoshida, M.(1989) J. Biochem. (Tokyo) 106, 730-734).

Adenosine Diphosphate↗