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Biomedical subjects

K Nemoto

Publications and source records attributed to K Nemoto.

At least 73 records · Page 4Linked to original sources
PubMed1999

Analysis of polymerization behavior of dental dimethacrylate monomers by differential scanning calorimetry.

The polymerization and copolymerization activity of dental monomers was investigated using the dynamic differential scanning calorimetry (DSC) method. As aliphatic dimethacrylate monomers, ethyleneglycol dimethacrylates with different lengths of ethyleneglycol and urethane dimethacrylates were used. As aromatic dimethacrylates, Bis-GMA (2,2-bis[4-(3-methacryloxy-2-hydroxypropoxy)phenyl]propane), BMPEPP (2,2-bis(4-methacryloxy poly-ethoxyphenyl)propane), and DMB (1,2-dimethacryloyloxy benzene) were used. Ethyleneglycol dimethacrylates showed sharp exothermic peaks, and the maximum temperatures (Tp) at the exothermic peaks of the DSC curves decreased according to the lengths of ethyleneglycols. Among urethane dimethacrylates, UDMA (dimethacryloxyethyl 2,2,4-trimethylhexamethylene diurethane) and DMPHU (di-(2-methacryloxypropyl) hexamethylene diurethane) showed sharp exothermic peaks, but DMEHU (di-(2-methacryloxyethyl) hexamethylene diurethane) showed an endothermic peak as well as exothermic peaks. This suggests that reactions other than polymerization occurred in the case of DMEHU. The polymerization activity of aromatic dimethacrylates was lower than that of ethyleneglycol dimethacrylates and urethane dimethacrylates. The copolymerization activity of TEGDMA (triethyleneglycol dimethacrylate) and DMB was also investigated using the dynamic DSC method. The DSC curves of the copolymerization between DMB and UDMA or BMPEPP showed broad peaks, but the DSC curves of the copolymerization between TEGDMA and UDMA or BMPEPP showed sharp peaks. The copolymerization activity of TEGDMA was better than that of DMB.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1999

Effectiveness of the addition of water-soluble photoinitiator into the self-etching primers on the adhesion of a resin composite to polished dentin and enamel.

The effectiveness of the addition of a photoinitiator into self-etching primer was investigated by measuring the tensile bond strength between a resin composite and dentin or enamel. The addition of camphorquinone to 5 M (5 wt% MDP -35 wt% HEMA aqueous solution) or 30 M (30 wt% MDP -35 wt% HEMA aqueous solution) did not increase the bond strengths of resin composite to dentin or enamel. On the other hand, the bond strength to dentin was increased by the addition of a water-soluble photoinitiator, 2-hydroxy-3-(3,4-dimethyl-9-oxo-9H-thioxanthen-2-yloxy)-N,N, N-trimethyl-1- propanaminium chloride (QTX) to 5 M or 30 M. The bond strengths to enamel were not influenced by the addition of QTX to 5 M or 30 M.

Acid Etching, Dental↗
PubMed1999

Immunosuppressant deoxyspergualin-induced inhibition of cell proliferation is accompanied with an enhanced reduction of tetrazolium salt.

Deoxyspergualin (DSG) has both antitumor and immunosuppressive activities. We explored the mechanism of DSG activities using an aqueous soluble analogue, methyldeoxyspergualin (MeDSG) for in vitro culture studies. It is known that DSG has inhibitory effects on cell proliferation, and we also observed that MeDSG inhibited [3H]-thymidine incorporation by rapidly dividing murine T cell hybridomas. However, when tetrazolium (MTT) colorimetric assay was adopted to evaluate its inhibitory effects on cell proliferation, MeDSG induced an enhanced MTT reduction. When we examined whether these results were applicable to the actively dividing cells of other origins than T cells, similar effects were seen with Raji cells, J774.1 cells and NIH3T3 cells. N-30, another analogue which was capable of suppressing anti-SRBC antibody production in vivo, also induced inhibition of cell growth and an enhanced MTT reduction. In contrast, the analogue which failed to prevent the antibody production, neither enhanced MTT reduction nor inhibited cell proliferation. Our results demonstrated that the ability to generate MTT formazan in dividing cells is a common property among, DSG analogue with the immunosuppressive and antiproliferative activities.

3T3 Cells↗
PubMed1999

[A case of spontaneous hemopneumothorax associated with uncontrolled massive bleeding after inserting thorathic drain].

A 31-year-old man admitted to our hospital complaining of right chest pain. Chest X-ray on admission revealed a collapsed lung and an air fluid line in the right thorax. A chest tube drainage was carried out, but hemorrhagic pleural fluid was drainaged. Forty minutes later, an anemia developed and chest X-ray showed increased massive right pleural collection. Therefore, emergent surgery was performed. An operation under thoracoscopic guidance was converted into thoracotomy because of massive blood clots and fresh bleeding. A bleeding originating from the branch of 1st intercostal artery and a bulla on upper lobes were noted. The artery was coagulated with electrocoutary and ligated using Endo-loop. This artery is not congenital abnormal one but collateral expanded one of which the elastic lamina is thickened. Spontaneous hemopneumothorax is life-threatening, emergent operation should be undergone.

Adult↗
PubMed1998

Increased uncoupling protein-2 and -3 gene expressions in skeletal muscle of STZ-induced diabetic rats.

Streptozotocin (STZ)-induced diabetic animals are vulnerable to cold stress. Uncoupling proteins (UCPs) play an important role in regulating thermogenesis. We investigated the gene expressions of UCPs in brown adipose tissue (BAT), white adipose tissue (WAT), liver and gastrocnemius muscle of STZ-diabetic rats using Northern blot. UCP-1, -2 and -3 mRNA expressions in BAT were all remarkably lower in STZ-diabetic rats than those in control rats. Both UCP-2 and -3 gene expressions in gastrocnemius muscle were substantially elevated in STZ-diabetic rats and insulin treatment restored UCP gene expressions to normal levels. These results suggest that in STZ-diabetic rats, the overexpression of UCP-2 and UCP-3 in skeletal muscle provides a defense against hypothermogenesis caused by decreased UCPs in BAT.

Adipose Tissue, Brown↗
PubMed1998

Novel alternative splicing in the 5' exon of the neurotrophin-3 gene.

The neurotrophin-3 (NT-3) gene has previously been reported to consist of three exons including two 5' short untranslated exons and a 3' long exon encoding the entire protein, and to give rise to two classes of transcripts by alternative splicing of the 5' exons to the 3' coding exon. In the present study, we demonstrated the presence of at least four new classes of transcripts of the NT-3 gene, in addition to the two known transcripts. The present finding proposes the further complexity of the regulational mechanism for NT-3 expression.

Alternative Splicing↗
PubMed1998

Membrane targeting and binding of the 74-kDa form of mouse L-histidine decarboxylase via its carboxyl-terminal sequence.

The role of the C-terminal region of the 74-kDa form of L-histidine decarboxylase (HDC) in the targeting to the endoplasmic reticulum (ER) was investigated in COS-7 cells. The deletion of a 10-kDa segment (residues 578-662) of the C-terminal end of HDC, especially a 20 amino acid sequence (residues 588-607), abrogated the targeting to the ER. The C-terminal 10-kDa portion is sufficient to target the green fluorescent protein (GFP) to the ER. The 74-kDa form of HDC synthesized in an in vitro translation system post-translationally associated with the heterogeneous canine microsomal membranes. These results suggest that the C-terminal 10-kDa portion of HDC contains a signal necessary for HDC to be targeted to the ER membrane.

Animals↗
PubMed1998

Adhesion mechanisms of resin to etched dentin primed with N-methacryloyl glycine studied by 13C-NMR.

The origin of the pH-dependent bond strength of the resin to etched dentin treated with N-methacryloyl glycine (NMGly) primer was studied by 13C-nuclear magnetic resonance (NMR) including spin-lattice relaxation time, T1, observation. When the dentinal collagen was suspended in the NMGly solution at pH = 1.6, the T1 values of all the carbons attributed to the NMGly species were significantly decreased. This indicated the presence of an interaction between the NMGly and the dentinal collagen. To obtain detailed information of this interaction, the 13C-NMR spectra of the NMGly were measured in the presence of the model compound for the collagen, (Pro-Pro-Gly)5 at pH = 1.7. The 13C-NMR peaks of the carbonyl carbons of the amide and carboxylic acid in the NMGly species shifted to a higher field and the T1 values decreased. Furthermore, when the molar ratio of (Pro-Pro-Gly)5 to NMGly was decreased from 1:1 to 1:3, the T1 values of the carbonyl carbon attributed to the carboxylic acid in the C-terminal Gly residue of the oligopeptide decreased dramatically. It can be construed that this indicated the formation of a hydrogen bond between the amide, -NH and the carboxylic acid of the NMGly species and the carboxylic acid of the C-terminal Gly residue of the oligopeptide.

Acid Etching, Dental↗
PubMed1998

Gene expression of neurotrophins and their receptors in cultured rat vascular smooth muscle cells.

Most previous researches on neurotrophins including nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin-3 (NT-3) have focused on the nervous system, because their receptors are widely distributed in neuronal tissues. Recently, however, the participation of neurotrophins in inflammation and atherosclerosis has been proposed. Therefore, the gene expression of neurotrophins is now an urgent issue is to be investigated in nonneuronal tissues. Here, we evaluated the gene expression of neurotrophins and their receptors in rat cultured vascular smooth muscle cells (VSMCs) by the reverse transcriptase-polymerase chain reaction method. The transcripts of NGF, NT-3, and TrkC (high-affinity receptor for NT-3), and two BDNF alternative spliced transcript variants with exons 3 and 4 were clearly detected in VSMCs cultured under conventional culture conditions. The upregulation of mRNA levels for NGF, two BDNF variants with exons 1 and 2, low-affinity neurotrophin receptor, and high-affinity receptors, TrkA (for NGF) and TrkB (for BDNF), was observed in response to the treatment with serum and phorbol-ester following the serum-starvation. In contrast, the expression of NT-3 and TrkC genes was downregulated under these conditions. Co-expression of these factors and their receptors and the characteristic regulation of their gene transcriptions suggest that these factors play crucial roles in the function of VSMCs through an autocrine mechanism.

Alternative Splicing↗
PubMed1998

Intracellular localization of the 74- and 53-kDa forms of L-histidine decarboxylase in a rat basophilic/mast cell line, RBL-2H3.

To clarify the process of post-translational modification of L-histidine decarboxylase (HDC), we investigated the conversion of the 74-kDa form of HDC into the 53-kDa form in specialized organella of a rat basophilic/mast cell line (RBL-2H3). With treatment of streptolysin-O, RBL-2H3 cells released approximately 40% of HDC activity accompanied by over 90% of lactate dehydrogenase activity. Only the 74-kDa form of HDC was detected in the leaked fraction by SDS-polyacrylamide gel electrophoresis. The 74-kDa form in the homogenate of pulse-labeled cells was recovered in both the supernatant and particulate fractions, while the 53-kDa form was detected only in the particulate fraction containing marker proteins of microsomes, Golgi, and lysosomal granules. Confocal microscopic observation using double staining immunofluorescence with anti-GST fusion HDC antiserum showed that most of the HDC coexists with protein-disulfide isomerase, a typical marker of the luminal space of the ER. With treatment of digitonin, RBL-2H3 cells released only 74-kDa HDC. Trypsin digestion of digitonin-permeabilized cells resulted in the disappearance of the 74-kDa form but not the 53-kDa form. From these results, it is assumed that the 74-kDa form of HDC, synthesized in the cytosol, is translocated into the lumen of the ER, where it is converted to the 53-kDa form.

Animals↗
PubMed1998

Down-regulation of RFL, the FLO/LFY homolog of rice, accompanied with panicle branch initiation.

FLORICAULA (FLO) of Antirrhinum and LEAFY (FLY) of Arabidopsis regulate the formation of floral meristems. To examine whether same mechanisms control floral development in distantly related species such as grasses, we isolated RFL, FLO-LFY homolog of rice, and examined its expression and function. Northern analysis showed that RFL is expressed predominantly in very young panicle but not in mature florets, mature leaves, or roots. In situ hybridization revealed that RFL RNA was expressed in epidermal cells in young leaves at vegetative growth stage. After the transition to reproductive stage, RFL RNA was detected in all layers of very young panicle including the apical meristem, but absent in the incipient primary branches. As development of branches proceeds, RFL RNA accumulation localized in the developing branches except for the apical meristems of the branches and secondary branch primordia. Expression pattern of RFL raised a possibility that, unlike FLO and LFY, RFL might be involved in panicle branching. Transgenic Arabidopsis plants constitutively expressing RFL from the cauliflower mosaic virus 35S promoter were produced to test whether 35S-RFL would cause similar phenotype as observed in 35S-LFY plants. In 35S-RFL plants, transformation of inflorescence meristem to floral meristem was rarely observed. Instead, development of cotyledons, rosette leaves, petals, and stamens was severely affected, demonstrating that RFL function is distinct from that of LFY. Our results suggest that mechanisms controlling floral development in rice might be diverged from that of Arabidopsis and Antirrhinum.

Amino Acid Sequence↗
PubMed1998

Sensitization of cells to ionizing radiation by chlorin e6Na.

We have investigated whether a hydrophilic photosensitizer, chlorin e6Na (Ce6Na), can sensitize cells to ionizing radiation. When V79-1 cells were pretreated with Ce6Na for 2 hr before receiving a dose of 2-14 Gy of irradiation, the cells became sensitive to X-irradiation. The sensitizing effect of Ce6Na depended on the dose of Ce6Na. The sensitizing effect also depended on the length of the treatment period before X-irradiation up to 4 hr, but not on the length of a treatment period after X-irradiation. Intracellular concentrations of Ce6Na were increased linearly after incubation with Ce6Na for periods of up to 4 h. The dose-modifying factor calculated from the survival curve was 1.25.

Animals↗
PubMed1998

Rice phloem thioredoxin h has the capacity to mediate its own cell-to-cell transport through plasmodesmata.

Rice (Oryza sativa L.) phloem sieve tubes contain RPP13-1, a thioredoxin h protein that moves around the plant via the translocation stream. Such phloem-mobile proteins are thought to be synthesized in the companion cells prior to being transferred, through plasmodesmata, to the enucleate sieve-tube members. In this study, in-situ hybridization experiments confirmed that expression of RPP13-1 is restricted to companion cells within the mature phloem. To test the hypothesis that RPP13-1 enters the sieve tube, via plasmodesmata, recombinant RPP13-1 was expressed in Escherichia coli, extracted, purified and fluorescently labeled with fluorescein isothiocyanate (FITC) for use in microinjection experiments into tobacco (Nicotiana tabacum L.) mesophyll cells. The FITC-RPP13-1 moved from the injected cell into surrounding cells, whereas the E. coli thioredoxin, an evolutionary homolog of RPP13-1, when similarly labeled and injected, failed to move in this same experimental system. In addition, co-injection of RPP13-1 and FITC-dextrans established that RPP13-1 can induce an increase in plasmodesmal size exclusion limit to a value greater than 9.4 but less than 20 kDa. Nine mutant forms of RPP13-1 were constructed and tested for their capacity to move from cell to cell; two such mutants were found to be incapable of movement. Crystal-structure prediction studies were performed on wild-type and mutant RPP13-1 to identify the location of structural motifs required for protein trafficking through plasmodesmata. These studies are discussed with respect to plasmodesmal-mediated transport of macromolecules within the companion cell-sieve tube complex.

Amino Acid Sequence↗
PubMed1998

Influence of water immersion stress on peripheral nerve recovery in the rat.

An experimental study was performed to investigate the relationship between stress and peripheral nerve recovery. Male Wistar rats weighing 200-250 g were used. The sciatic nerve was crushed unilaterally with an aneurysm clip. Stress was applied by water immersion for 3 h, three times a week, from 1 week preoperatively, and continued for 6 or 8 weeks. The animals' walking tracks were measured every week to evaluate nerve function, and a sciatic functional index (SFI) was calculated. Specimens for histological examination were taken from the nerve at a site distal to the crush injury. By 3 weeks postoperatively, the SFI in the non-stress groups had recovered, but it remained at significantly lower levels in the stress groups (P < 0.01). Histological studies showed that the recovery of nerve fibers was retarded and regenerating axons were smaller in the stress groups. Peripheral nerve recovery after crush injury was suppressed by water-immersion stress.

Analysis of Variance↗
PubMed1998

Potentiation of retinoic acid-induced differentiation of HL-60 cells by prostaglandin EP2 receptor.

Human promyeloid HL-60 cells are differentiated by all-trans retinoic acid (RA) to granulocytes, and prostaglandin (PG) E2 potentiates the RA-induced differentiation. Here we examined which subtype of PGE receptors was involved in this potentiating activity of PGE2. Northern blot analysis demonstrated that HL-60 cells expressed three subtypes of PGE receptor, EP2, EP3, and EP4. Among various EP agonists, and EP2-selective agonist, butaprost, preferentially potentiated the RA-induced differentiation of HL-60 cells. Butaprost not only decreased the half-maximal concentration of RA but also increased the maximal level of the differentiation. Butaprost concentration-dependently stimulated the cAMP formation, and 8-Br-cAMP strongly potentiated the RA-induced differentiation. These results demonstrate that the EP2 receptor enhances the RA-induced differentiation of HL-60 cells via stimulation of adenylate cyclase.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1998

Influence of self-etching primer treatment on the adhesion of resin composite to polished dentin and enamel.

OBJECTIVE: This study investigated the effectiveness of the self-etching primer treatment on the adhesion of resin composite to both dentin and enamel. METHODS: Two types of self-etching primer were prepared. One was an aqueous solution of 2-methacryloyloxyethyl phenyl hydrogen phosphate (Phenyl-P) and 2-hydroxyethyl methacrylate (HEMA), and the other was an aqueous solution of 10-methacryloxydecyl dihydrogen phosphate (MDP) and HEMA. Influence of the concentration of Phenyl-P and MDP, and that of the application time on the adhesiveness were examined by measuring the tensile bond strengths of resin composite to dentin and enamel. The data were analyzed using the analysis of variance and Scheffe's test for multiple comparison among the means. RESULTS: After the 20P and 30P treatment for 30 s, bond strengths to dentin were significantly higher than those after 5P and 10P treatment for 30 s. The 30M treatment of dentin for 15 s significantly increased the bond strength compared with 5P, 10P and 20P for 15 s. In enamel, bond strength with 30P for 60 s was significantly higher than with 5P for 60 s and 30P for 15 s. The 30M for 60 s resulted in significantly higher bond strength than for 15 s. The smear layers on the dentin and enamel were partially dissolved by the self-etching primer treatment. A hybrid layer with a thickness of 1-1.5 microns was formed in dentin-bonded specimens. SIGNIFICANCE: The self-etching primer containing Phenyl-P or MDP showed good adhesion to dentin and enamel, and this primer is a promising material for resin composite restoration.

Acid Etching, Dental↗
PubMed1998

Deoxyspergualin preferentially inhibits the growth and maturation of anti-CD40-activated surface IgD+ B lymphocytes.

Deoxyspergualin (DSG), an analogue of spermidin, is a potent immunosuppressive drug with an action quite distinct from that of cyclosporin, rapamycin, or FK506. In this study we investigated the effect of DSG and methyldeoxyspergualin (MeDSG) on the proliferation and differentiation of human B cells stimulated with anti-CD40 MoAb. Highly purified B cells obtained from tonsillar samples were used as target cells. Both agents inhibited the proliferative response of anti-CD40-stimulated B cells in the absence and presence of IL-4, IL-2 or IL-10 in a dose-dependent manner. This inhibitory effect differed markedly among cell populations based on surface IgD expression: strong inhibition of sIgD+ B cells but little inhibition of sIgD- B cells. The drugs also suppressed the production of IgG, IgM and IgA by unfractionated B cells, which suggests that DSG acts against post-switch (sIgD-) B cells. Although the drugs suppressed immunoglobulin synthesis by both sIgD+ and sIgD- B cells, the effect was more marked in the sIgD+ B cells. Analysis of the subclass of IgG secreted by sIgD+ B cells revealed a decline in IgG1 and IgG3 in the presence of DSG. These results suggest that DSG preferentially inhibits the growth and maturation of sIgD+ naive B cells.

Antibodies, Monoclonal↗