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Biomedical subjects

H Ohno

Publications and source records attributed to H Ohno.

At least 91 records · Page 5Linked to original sources
PubMed2001

Resin-tooth adhesive interfaces after long-term function.

PURPOSE: To characterize with scanning electron microscopy (SEM), the morphology of adhesive interfaces that had been functioning in an oral cavity for several years. MATERIALS AND METHODS: Cavities were prepared in vivo in caries-affected primary molars under local anesthesia. After removal of the entire carious lesion, the cavity was restored with a dentin adhesive system (Scotchbond Multi-Purpose). After several yrs, as the successor permanent teeth erupted, the resin-filled teeth were extracted. Then, the extracted resin-restored primary molars were cross-sectioned perpendicular to the adhesive interface using a low speed diamond saw and then polished for SEM examination. RESULTS: Morphological changes, such as digestion of the collagen fibrils and deterioration of the bonding resin and hybrid layer, were observed at the interface of the oral environment specimens. The results of this study demonstrated that degradation of resin-dentin bond structures appeared to occur in the human oral environment over time.

Child↗
PubMed2001

Fractographical analysis of resin-dentin bonds.

PURPOSE: To characterize resin-dentin bond structures of three adhesive resin systems using fractographic analysis to measure the area of failure at the fractured surface. MATERIALS AND METHODS: Flat dentin surfaces were ground perpendicular to the long axis of the tooth. The prepared dentin surfaces were treated by one of three adhesive resin systems (Mac Bond II, One-Step, and Single Bond). The samples were sectioned perpendicular to the adhesive interface to produce a square bar-shaped specimen (adhesive area: 0.9 mm2) using a diamond saw. A micro-tensile test was then conducted at a crosshead speed of 1.0 mm/min. The mean tensile bond strengths were statistically compared using one-way ANOVA and Fisher's PLSD test (P< 0.05). The fractured surfaces of all specimens were examined using SEM and the area of failure was measured using an image analyzer on SEM microphotographs. RESULTS: No significant differences in tensile bond strength were observed between Single Bond (62.1+/-18.2 MPa) and One-Step (53.8+/-13.1 MPa) (P > 0.05). However, the bond strength of Mac Bond II (36.5+/-13.7 MPa) was significantly lower than that of One-Step or Single Bond (P< 0.05). At the fractured surface, except for the cohesive failure of the bonding resin and resin-based composite, different failure patterns were observed for each resin system as follows: the failure of the hybrid layer and demineralized dentin was observed in the two wet bonding systems (One-Step and Single Bond) and of the hybrid layer but not the demineralized dentin in the self-etching primer system (Mac Bond II). The results demonstrated that the integrity of the hybrid layer depends on the adhesive system.

Analysis of Variance↗
PubMed2000

Cell surface expression of calnexin, a molecular chaperone in the endoplasmic reticulum.

The folding and assembly of nascent proteins in the endoplasmic reticulum are assisted by the molecular chaperone calnexin, which is itself retained within the endoplasmic reticulum. It was up to now assumed that calnexin was selectively expressed on the surface of immature thymocytes because of a particular characteristic of the protein sorting machinery in these cells. We now report that a small fraction of calnexin is normally expressed on the surface of various cells such as mastocytoma cells, murine splenocytes, fibroblast cells, and human HeLa cells. Surface biotinylation followed by chase culture of living cells revealed that calnexin is continuously delivered to the cell surface and then internalized for lysosomal degradation. These results suggest that there is continuous exocytosis and endocytosis of calnexin, and the amount of calnexin on the plasma membrane results from the balance of the rates of these two events. To study the structural requirement of calnexin for surface expression, we created deletion mutants of calnexin and found that the luminal domain, particularly the glycoprotein binding domain, is necessary. These findings suggest that the surface expression of calnexin depends on the association with glycoproteins and that calnexin may play a certain role as a chaperone on the plasma membrane as well.

Amino Acid Motifs↗
PubMed2000

Regular training modulates the accumulation of reactive carbonyl derivatives in mitochondrial and cytosolic fractions of rat skeletal muscle.

The oxygen flux into the mitochondria of skeletal muscle increases with exercise. However, the extent of oxidative damage to mitochondrial proteins of skeletal muscle has only been estimated. We studied the alteration of reactive carbonyl derivatives (RCD) in mitochondrial and cytosolic fractions of skeletal muscle following 9 weeks of swimming training in rats. The RCD content of mitochondria was significantly elevated compared with the cytosolic fraction of both control and exercised animals. Accumulation of RCD in muscle mitochondria of the exercised group was also significantly elevated (P < 0.05). On the other hand, alteration of the accumulation of RCD was not apparent in the cytosolic fraction of skeletal muscle. The activity of proteasome complex, however, was increased in the cytosolic fraction of exercised muscle (P < 0.05). The data suggest that mitochondria of skeletal muscle accumulate significantly larger amounts of RCD than the cytosolic fraction and the tendency of the accumulation varies in cell fractions. Exercise training increases the accumulation of protein damage in mitochondria of skeletal muscle but cytosolic proteins are protected by increased activity of proteasome complex and possibly by other antioxidant enzymes.

Animals↗
PubMed2000

Regulation of cell surface expression of CTLA-4 by secretion of CTLA-4-containing lysosomes upon activation of CD4+ T cells.

CTLA-4 is expressed on the surface of activated T cells and negatively regulates T cell activation. Because a low-level expression of CTLA-4 on the cell surface is sufficient to induce negative signals in T cells, the surface expression of CTLA-4 is strictly regulated. We previously demonstrated that the association of CTLA-4 with the clathrin-associated adaptor complex AP-2 induces internalization of CTLA-4 and keeps the surface expression low. However, the mechanism to induce high expression on the cell surface upon stimulation has not yet been clarified. To address this, we investigated the intracellular dynamics of CTLA-4 by analyzing its localization and trafficking in wild-type and mutant CTLA-4-transfected Th1 clones. CTLA-4 is accumulated in intracellular granules, which we identified as lysosomes. CTLA-4 is degraded in lysosomes in a short period, and the degradation process may serve as one of the mechanisms to regulate CTLA-4 expression. Upon TCR stimulation, CTLA-4-containing lysosomes are secreted as proven by the secretion of cathepsin D and beta-hexosaminidase in parallel with the increase of surface expression of CTLA-4 and lysosomal glycoprotein 85, a lysosomal marker. These results suggest that the cell surface expression of CTLA-4 is up-regulated upon stimulation by utilizing a mechanism of secretory lysosomes in CD4(+)T cells.

Abatacept↗
PubMed2000

Nonimmunoglobulin (non-Ig)/BCL6 gene fusion in diffuse large B-cell lymphoma results in worse prognosis than Ig/BCL6.

Chromosomal translocation involving the BCL6 gene affects not only immunoglobulin (Ig) genes but also a number of non-Ig genes as partners. The molecular anatomy of the BCL6 gene rearrangements in 39 cases with diffuse large B-cell lymphoma (DLBCL) by long-distance polymerase chain reaction-based assays was determined. The results showed that Ig genes were affected in 21 cases; non-Ig genes, 15 cases; a deletion of more than a 1-kb segment, 2 cases; and a point mutation, 1 case. Comparative studies between the 21 cases with Ig gene partners and the 17 cases with non-Ig gene partners, including 2 cases with the deletion, showed that the overall survival of the latter group of patients was significantly inferior to that of the former (P = .0440), and the estimated 2-year overall survival rates were 58.3% vs 17.6% (P = .005). Non-Ig/BCL6 fusion is a poor prognostic indicator of DLBCL, and DLBCL with BCL6 translocation could be subclassified according to the individual partner locus and/or gene. (Blood. 2000;96:2907-2909)

Adult↗
PubMed2000

A Di-leucine signal in the ubiquitin moiety. Possible involvement in ubiquitination-mediated endocytosis.

Some plasma membrane receptors in yeast are known to be internalized and degraded in lysosomes upon ligand-dependent ubiquitination. However, the role of ubiquitination in endocytosis and lysosomal degradation in higher eukaryotes has been controversial. In order to directly assess this question, we investigated the fate of chimeric molecules in which ubiquitin moiety was fused in-frame to the cytoplasmic region of membrane proteins. The chimeric proteins with the wild-type ubiquitin were endocytosed and delivered to lysosomes efficiently. Mutant ubiquitin with lysine-to-arginine substitution could still mediate endocytosis, suggesting that polyubiquitination is not required for the endocytosis. We next searched for the existence of an endocytosis signal(s) in the ubiquitin moiety, and identified a di-leucine signal, Leu(43)-Ile(44). The Leu(43)-Ile(44) sequence mediated endocytosis and lysosomal sorting in a Leu(43)-dependent manner. These results suggest that the di-leucine signal in ubiquitin can be involved in ubiquitination-mediated endocytosis and lysosomal targeting of membrane proteins.

Amino Acid Sequence↗
PubMed2000

ADAMTS-1 cleaves a cartilage proteoglycan, aggrecan.

A disintegrin-like and metalloproteinase with thrombospondin type I motifs-1 (ADAMTS-1) is an extracellular matrix-anchored metalloproteinase. In this study we have demonstrated that ADAMTS-1 is able to cleave a major cartilage proteoglycan, aggrecan. N-terminal sequencing analysis of the cleavage product revealed that ADAMTS-1 cleaves the Glu(1871)-Leu(1872) bond within the chondroitin sulfate attachment domain of aggrecan. In addition, deletional analysis demonstrated that the C-terminal spacer region of ADAMTS-1 is necessary to degrade aggrecan. These results suggest that ADAMTS-1 may be involved in the turnover of aggrecan in vivo.

ADAM Proteins↗
PubMed2000

Umpolung of chiral 2-ethynylaziridines: Indium(I)-mediated stereoselective synthesis of nonracemic 1,3-amino alcohols bearing three chiral centers, catalyzed by palladium(0)

Treatment of 3-alkyl-2-ethynylaziridines with InI in the presence of Pd(PPh(3))(4) and H(2)O gave allenylindium reagents bearing a protected amino group in high yields. Stereoselective addition of the allenylindium to aldehydes affords 2-ethynyl-1,3-amino alcohols bearing three chiral centers in good yields.

Journal Article↗
PubMed2000

Superoxide dismutase gene expression in skeletal muscle: fiber-specific effect of age.

The influence of ageing on the expression of two superoxide dismutase (SOD) isozymes was examined in three different skeletal muscle fiber types of young (Y, 8 mo) and old (O, 25 mo) rats. Total SOD activity was increased with age in the gastrocnemius (Gas, type II(mix)) and superficial vastus lateralis (SVL, type IIb) but unchanged in the soleus (Sol, type I). The increased SOD activity in SVL was due to increased cytosolic SOD (CuZn SOD), whereas both mitochondrial (Mn SOD) and CuZn SOD activities were increased in Gas. In Sol, Mn SOD activity was significantly increased in aged rats. Mn SOD mRNA level was significantly decreased with age in all three muscles examined, while Mn SOD protein content was not altered. Ageing did not affect CuZn SOD mRNA abundance in any of the muscles, but significantly increased CuZn SOD protein content in aged Gas and Sol. Binding of two redox-sensitive transcription factors, nuclear factor-kappaB (NFkappaB) and activator protein-1 (AP-1) was significantly decreased with age in all three muscle types. These results indicate that increased SOD activity in aged skeletal muscle is not associated with higher levels of gene transcription. Increases in Mn SOD activity seen in aged Gas and Sol are the result of post-translational modification of the enzyme, whereas increases in CuZn SOD activity during ageing may be due to both translational and post-translational control.

Aging↗
PubMed2000

Molecular anatomy of BCL6 translocations revealed by long-distance polymerase chain reaction-based assays.

BCL6 translocations involve not only immunoglobulin (IG) genes but also a number of non-IG loci as partners. Junctional sequences of three IG/BCL6 translocations were readily obtained by long-distance PCR. In cases where partner loci were not determined, we developed a long-distance inverse PCR method, which amplifies unknown fragments flanked by known BCL6 sequences. Using these two long-distance PCR-based approaches, we cloned junctional areas of BCL6 translocations from a total of 58 cases of B-cell tumors. Nucleotide sequencing and database searches revealed that 30 cases involved IGs as partners: IG heavy chain gene in 22, IG kappa light chain gene in 1, and IG lambda light chain gene in 7. In contrast, 23 cases affected non-IG loci, including the H4 histone gene, heat shock protein genes HSP89alpha and HSP90beta, and PIM-1 proto-oncogene. On der(3) chromosomes, complete sets of the promoters of these partner genes replaced that of BCL6 in the same transcriptional orientation. These results suggest that BCL6 gene affected by the translocation is transcriptionally activated by a variety of stimuli, including cell cycle control, changes in the physical environment, and response to cytokines. Break points on BCL6 occurred within the major translocation cluster, and we identified a 120-bp hyper-cluster region a short distance from the 3' end of exon 1. Gel mobility-shift assay suggested the presence of a protein(s) that bound to this particular region.

Base Sequence↗
PubMed2000

Zener model description of ferromagnetism in zinc-blende magnetic semiconductors

Ferromagnetism in manganese compound semiconductors not only opens prospects for tailoring magnetic and spin-related phenomena in semiconductors with a precision specific to III-V compounds but also addresses a question about the origin of the magnetic interactions that lead to a Curie temperature (T(C)) as high as 110 K for a manganese concentration of just 5%. Zener's model of ferromagnetism, originally proposed for transition metals in 1950, can explain T(C) of Ga(1-)(x)Mn(x)As and that of its II-VI counterpart Zn(1-)(x)Mn(x)Te and is used to predict materials with T(C) exceeding room temperature, an important step toward semiconductor electronics that use both charge and spin.

Journal Article↗
PubMed2000

CSF phosphorylated tau protein and mild cognitive impairment: a prospective study.

Cerebrospinal fluid (CSF) tau protein phosphorylated at both Thr231 and Ser235 sites (CSF/phospho-tau(231-235)) and total tau (CSF/total-tau) were quantified by sandwich ELISA in 20 patients with mild cognitive impairment (MCI) who eventually developed AD on follow-up as well as seven memory complainers with no objective memory loss. 13/20 (65%) of the MCI patients had high CSF/total-tau and detectable levels of CSF/phospho-tau(231-235), whereas these markers were low and under a detectable level in all of the memory complainers. Although either a total-tau, phospho-tau measurement or a combination of these can help in predicting if MCI will develop AD, our results suggest that the pathogenic steps of AD may be at the stage that finally leads to an accumulation of abnormally phosphorylated tau and neuron death, at least in some brain areas, when MCI patients present with the earliest detectable clinical symptoms of dementia.

Aged↗
PubMed2000

[Humeral lengthening and deformity correction].

Nine patients with achondroplasia and one patient with Apert syndrome underwent the surgical lengthening of both humerus and simultaneous correction of both associated bone deformity. An unilateral external fixator was applied to the lateral aspect of the humerus with four half-pins and percutaneous predrilling osteotomy was performed at the apex of flexion deformity of the bone. During the waiting period before distraction, the flexion deformity of the distal humerus was corrected using an additional external fixator. Slow gradual distraction was subsequently carried out at a rate of 0. 25 mm every 6 hours. The average lengthening was 8 cm (range 7.5 to 9 cm), the overall treatment time 312 days (range 192 to 406 days), and the average healing index 39.0 days/cm. The average correction of the elbow flexion deformity was 20 degrees. We believe this treatment is useful to improve the function of the arms and the activity of daily living for the patients with bilateral short humeri.

Achondroplasia↗
PubMed2000

Mediastinal irrigation with superoxidized water after open-heart surgery: the safety and pitfalls of cardiovascular surgical application.

Postoperative mediastinal infection after open-heart surgery via median sternotomy is a devastating complication. In this paper, we describe a simple method of irrigating the mediastinum using superoxidized water to prevent perioperative contamination. After mediastinal hemostasis was done, warm superoxidized water of more than 21 was uninterruptedly irrigated for 5 min immediately prior to sternal closure. We have used this method in 25 patients undergoing cardiac surgery, and noted significant perioperative electrocardiographic changes, including ST elevation, without hemodynamic compromise in 15 of these patients.

Cardiac Surgical Procedures↗
PubMed2000

Inhibition of adipocyte lipolysis by papaverine: papaverine can inhibit the redistribution of hormone-sensitive lipase.

Papaverine, despite being a potent phosphodiesterase inhibitor, actually blocks adipocyte lipolysis. The present study was designed to clarify the mechanism of the inhibitory effect of papaverine on lipolysis. Lipolysis, stimulated by either 10 microM isoproterenol or 5 mM dibutyryl cAMP, was significantly inhibited by papaverine (100 microM and above). Papaverine, however, did not affect the isoproterenol-induced increase in the protein kinase A (A-kinase) activity ratio. In cell-free extract from non-stimulated adipocytes, cAMP-stimulated A-kinase activities were almost completely blocked by H-89, a potent inhibitor of A-kinase, but not by papaverine. Thus, the inhibitory effect of papaverine on lipolysis could be responsible for a deficit in step(s) distal to A-kinase activity. Hormone-sensitive lipase activities in the infranatant fraction of centrifuged homogenates of cells, which were maximally stimulated with isoproterenol were significantly reduced. This result indicates that hormone-sensitive lipase redistributes from cytosol to its substrate in lipolytically stimulated cells. Papaverine completely blocked the isoproterenol-induced decrease in lipase activity in the infranatant fraction. These results suggest that papaverine blocks lipolysis through its inhibitory effect on the redistribution of hormone-sensitive lipase.

Adipocytes↗