Biomedical subjects

K Nakashima

Publications and source records attributed to K Nakashima.

At least 181 records · Page 10Linked to original sources

PubMed2000

Effect of temporary materials on bond strength of resin-modified glass-ionomer luting cements to teeth.

PURPOSE: To evaluate the effect of temporary materials on the bond strength of resin-modified glass-ionomer luting cements to teeth. MATERIALS AND METHODS: 240 freshly extracted bovine central incisors were ground to expose enamel and dentin surface. Fuji Lute and Vitremer Luting Cement were bonded to enamel and dentin surfaces after pretreatment for 1 week with (1) a eugenol-containing cement (Propac), (2) a eugenol-free cement (Freegenol Temporary Pack), (3) a polycarboxylate cement (HY-Bond Temporary Cement Hard), (4) a chemically cured temporary restorative resin (Plast Seal), and (5) a light-cured temporary restorative resin (Fermit). The flattened enamel and dentin surfaces were used as controls. After bonded specimens were stored in water at 37 degrees C for 24 hrs, the tensile bond strength was measured at a crosshead speed of 0.5 mm/min. The data were statistically analyzed by one-way ANOVA and Dunnett's Post-hoc Procedure (P < 0.05). RESULTS: Plast Seal had no adverse effect on the tensile bond strength of Fuji Lute on both enamel and dentin surfaces, while the other temporary materials revealed significant decrease in bond strength. In Vitremer Luting Cement, Propac, and Fermit, as well as Plast Seal demonstrated tensile bond strengths similar to the controls.

Analysis of Variance↗

PubMed1999

Molecular characterization of peptidylarginine deiminase in HL-60 cells induced by retinoic acid and 1alpha,25-dihydroxyvitamin D(3).

Three types of peptidylarginine deiminase (PAD), which converts a protein arginine residue to a citrulline residue, are widely distributed in animal tissues. Little is known about PAD of hemopoietic cells. We found that PAD activity in human myeloid leukemia HL-60 cells was induced with the granulocyte-inducing agents retinoic acid and dimethyl sulfoxide and with the monocyte-inducing agent 1alpha,25-dihydroxyvitamin D(3). We cloned and characterized a PAD cDNA from retinoic acid-induced cells. The cDNA was 2,238 base pairs long and encoded a 663-amino acid polypeptide. The HL-60 PAD had 50-55% amino acid sequence identities with the three known enzymes and 73% identity with the recently cloned keratinocyte PAD. The recombinant enzyme differs in kinetic properties from the known enzymes. Immunoblotting and Northern blotting with an antiserum against the enzyme and the cDNA, respectively, showed that a protein of approximately 67 kDa increased concomitantly with increase of mRNA of approximately 2.6 kilobases during granulocyte differentiation. During monocyte differentiation the same mRNA and protein increased as in granulocyte differentiation. Neither the enzyme activity nor the protein was found in macrophage-induced cells. These results suggested that expression of the PAD gene is tightly linked to myeloid differentiation.

Amino Acid Sequence↗

PubMed1999

Astrocyte differentiation mediated by LIF in cooperation with BMP2.

Leukemia inhibitory factor (LIF) and bone morphogenetic protein (BMP) 2 signal via different receptor systems. We have recently demonstrated that simultaneous stimulation of fetal mouse neuroepithelial cells with these distinct types of cytokines synergistically induces astrocyte differentiation in a 2-day culture. Here we show that astrocytes spontaneously emerge in vitro without exogenously added LIF and BMP2 in the culture of neuroepithelial cells for a much longer period. This spontaneous astrocyte differentiation is completely impaired when neuroepithelial cells deficient for gp130, a signal transducing receptor component for LIF, are used. We also show that LIF and BMP2 as well as related cytokines and respective receptor molecules are expressed in fetal mouse brain and cultured neuroepithelial cells. Taken together with our previous finding that prenatal mouse brain deficient for gp130 exhibits a severe reduction of astrocytes, it is suggested that LIF acts cooperatively with BMP2 in vivo to induce astrocyte differentiation in mouse developing brain.

Animals↗

PubMed1999

STAT3-mediated astrocyte differentiation from mouse fetal neuroepithelial cells by mouse oncostatin M.

The interleukin (IL)-6 family of cytokines share gp130 as a signal-transducing receptor component. We here show that oncostatin M (OSM), a member of this family, and its receptor components were expressed in embryonic mouse brain and that OSM induced astrocytes in cultured fetal mouse neuroepithelial cells. OSM induced promoter activation of the gene for an astrocyte marker, glial fibrillary acidic protein. The activation was completely blocked by expression of a dominant negative form of STAT3, a transcription factor activated downstream of gp130, or by introduction of a mutation in the STAT3 binding motif in the promoter. Taken together with its expression, we suggest that OSM contributes to the induction of astrocyte differentiation in a fetal developing brain via STAT3 activation.

Acute-Phase Proteins↗

PubMed1999

Developmental requirement of gp130 signaling in neuronal survival and astrocyte differentiation.

gp130 is a signal-transducing receptor component used in common by the interleukin-6 (IL-6) family of hematopoietic and neurotrophic cytokines, including IL-6, IL-11, leukemia-inhibitory factor, ciliary neurotrophic factor, oncostatin-M, and cardiotrophin-1. We have examined in this study a role of gp130 in the nervous system by analyzing developmental cell death of several neuronal populations and the differentiation of astrocytes in gp130-deficient mice. A significant reduction was observed in the number of sensory neurons in L5 dorsal root ganglia and motoneurons in the facial nucleus, the nucleus ambiguus, and the lumbar spinal cord in gp130 -/- mice on embryonic day 18.5. On the other hand, no significant neuronal loss was detectable on day 14.5, suggesting a physiological role of gp130 in supporting newly generated neurons during the late phase of development when naturally occurring cell death takes place. Moreover, expression of an astrocyte marker, GFAP, was severely reduced in the brain of gp130 -/- mice. Our data demonstrate that gp130 expression is essential for survival of subgroups of differentiated motor and sensory neurons and for the differentiation of major populations of astrocytes in vivo.

Animals↗

PubMed1999

A complementary peptide vaccine that induces T cell anergy and prevents experimental allergic neuritis in Lewis rats.

We have developed and described a new method of altering T cell-mediated autoimmune diseases by immunization with the complementary peptide against T cell epitopes. The complementary peptide (denoted NAE 07-06) to the bovine P2 protein, residues 60-70 (denoted EAN 60-70), was tested in the Lewis rat model of experimental allergic neuritis (EAN). Immunization with NAE 07-06 induced polyclonal and monoclonal Abs that inhibited the proliferation of the P2-specific T cell line, stimulated with EAN 60-70, and recognized Vbeta, but not Valpha, of TCRs. Proliferation of T cells treated with anti-NAE 07-06 Abs could be partially restored by treatment with rIL-2, in accordance with an anergy model. A homologous sequence was found between NAE 07-06 and the VDJ junction of the TCR beta-chain from an EAN 60-70-specific T cell line. Rats preimmunized with NAE 07-06 in vivo before EAN induction showed less disease severity clinically and histologically. These data suggest a new therapeutic approach for T cell-mediated autoimmune disorders through the induction of anti-TCR Abs with complementary peptide Ags.

Animals↗

PubMed1999

Inhibitory effect of lipopolysaccharide on apoptotic cell death in macrophages infected with Actinobacillus actinomycetemcomitans.

We have reported that the macrophage-like cell line J774.1, when infected with the periodontopathic bacterium Actinobacillus actinomycetemcomitans, undergoes apoptosis. In this study, we examined whether stimulation of J774.1 cells with lipopolysaccharide (LPS) before the infection affects the subsequent apoptosis. Cytotoxicity on the LPS-stimulated cells was about half of the unstimulated control cells. DNA fragmentation in the LPS-stimulated cells was also significantly lower than in the control cells, whereas it was increased to a level similar to that of the control cells by addition of a nitric oxide (NO) inhibitor. In addition, significantly smaller numbers of live A. actinomycetemcomitans were recovered from the LPS-stimulated macrophages at 8 h after the infection as compared with the control cells. These findings suggest that the inhibitory effect of LPS on apoptosis results from an enhanced NO-mediated bactericidal activity.

Aggregatibacter actinomycetemcomitans↗

PubMed1999

Effects of kainate-mediated excitotoxicity on the expression of rat counterparts of A170 and MSP23 stress proteins in the brain.

Stress proteins play important roles in the protective mechanisms under critical conditions for cell survival. We report here the expression of A170 and MSP23, oxidative stress-inducible proteins, under kainate-mediated excitotoxicity in the rat brain. A170 mRNA was significantly induced in the brain 5-8 h after i.p. kainate administration. MSP23 mRNA was observed at quite a low level in the rat brain, and the induction of MSP23 mRNA was not observed during the period 24 h after kainate administration. Immunoblot analysis demonstrated that the maximal expression level of A170 protein occurred 8 h after treatment in each part of the brain. MSP23 protein was constitutively expressed in the brain and the level of this protein was significantly decreased during the period 24 h after kainate administration. In situ hybridization and immunohistochemical studies showed that A170 was expressed predominantly in neurons, especially in pyramidal neurons of the cerebrum and cerebellar Purkinje cells, while MSP23 was expressed in oligodendrocytes. The induction of A170 was observed in the regions which are affected by excitotoxicity and this induction was observed in the earlier phase than cell death. Also, the region which shows high vulnerability to excitotoxicity such as pyramidal cell layer in the hippocampus, showed lower A170 expression than that which shows resistance to excitotoxicity, such as the dentate gyrus in the hippocampus. These results suggest that A170 may play a protective role in the brain under kainate-mediated excitotoxicity.

Animals↗

PubMed1999

A novel mammalian T-box-containing gene, Tbr2, expressed in mouse developing brain.

We have identified and characterized a new member of the mammalian brain-specific T-box gene family, Tbr2, which is closely related to mouse Tbr1, and to the Xenopus earliest mesodermal gene, Eomesodermin. As Tbr1, Tbr2 is predominantly expressed in some regions of the developing brain, but in a strikingly complementary manner. On embryonic day 14.5 (E14.5), Tbr2 mRNA expression was observed in the mesencephalon and rhombencephalon in contrast to Tbr1 which was expressed mostly in the telencephalon. At this stage, Tbr2 mRNA was readily detectable in the postmitotic and differentiating neurons located in various brain regions, i.e., oculomotor, red, trigeminal, vestibular, facial, and hypoglossal nuclei. However, expression of Tbr2 in these nuclei became undetectable on E18.5. In contrast, Tbr2 mRNA expression was detected in the hippocampus only from E18.5 onwards. Whereas Tbr2 expression disappeared in most parts of the mature adult brain, it remained detectable in the hippocampus and olfactory bulb, regions where some neuronal precursors retain their differentiation potential. These results suggest that Tbr2 may play a crucial role in differentiating neurons rather than in proliferating or already differentiated neurons. In addition, similarly to Xenopus Eomesodermin, mouse Tbr2 showed biphasic expression; a first peak around E6.5 and a second peak around E14.5, suggesting that Tbr2 may also be important at early stages of gastrulation.

Amino Acid Sequence↗

PubMed1999

Induction of heme oxygenase-1 in the rat brain by kainic acid-mediated excitotoxicity: the dissociation of mRNA and protein expression in hippocampus.

Heme oxygenase-1 (HO-1) is induced under various stresses. Here we report the induction and localization of HO-1 in the rat brain by intraperitoneal administration of kainic acid (KA). Both mRNA and protein of HO-1 were markedly induced by KA treatment, and each maximal induction was observed 24 h after KA administration. In situ hybridization analysis showed that HO-1 mRNA appeared predominantly in glial cells, and confined neurons were positive in the cerebral cortex, basal ganglia, and hippocampal pyramidal cell layer. Immunohistochemical analysis showed that the positive cells in the cerebral cortex and hippocampus were mainly astrocytes and microglia, whereas neurons in the basal ganglia showed intense immunoreactivity. We also demonstrate the dissociation between HO-1 mRNA and protein level in the hippocampal pyramidal neurons, which is known to be vulnerable against excitotoxicity, and discuss the correlation between this dissociation and the vulnerability of hippocampal pyramidal neurons.

Animals↗

PubMed1999

Synergistic signaling in fetal brain by STAT3-Smad1 complex bridged by p300.

The cytokines LIF (leukemia inhibitory factor) and BMP2 (bone morphogenetic protein-2) signal through different receptors and transcription factors, namely STATs (signal transducers and activators of transcription) and Smads. LIF and BMP2 were found to act in synergy on primary fetal neural progenitor cells to induce astrocytes. The transcriptional coactivator p300 interacts physically with STAT3 at its amino terminus in a cytokine stimulation-independent manner, and with Smad1 at its carboxyl terminus in a cytokine stimulation-dependent manner. The formation of a complex between STAT3 and Smad1, bridged by p300, is involved in the cooperative signaling of LIF and BMP2 and the subsequent induction of astrocytes from neural progenitors.

Animals↗

PubMed1999

Fetal liver development requires a paracrine action of oncostatin M through the gp130 signal transducer.

Fetal liver, the major site of hematopoiesis during embryonic development, acquires additional various metabolic functions near birth. Although liver development has been characterized biologically as consisting of several distinct steps, the molecular events accompanying this process are just beginning to be characterized. In this study, we have established a novel culture system of fetal murine hepatocytes and investigated factors required for development of hepatocytes. We found that oncostatin M (OSM), an interleukin-6 family cytokine, in combination with glucocorticoid, induced maturation of hepatocytes as evidenced by morphological changes that closely resemble more differentiated hepatocytes, expression of hepatic differentiation markers and intracellular glycogen accumulation. Consistent with these in vitro observations, livers from mice deficient for gp130, an OSM receptor subunit, display defects in maturation of hepatocytes. Interestingly, OSM is expressed in CD45(+) hematopoietic cells in the developing liver, whereas the OSM receptor is expressed predominantly in hepatocytes. These results suggest a paracrine mechanism of hepatogenesis; blood cells, transiently expanding in the fetal liver, produce OSM to promote development of hepatocytes in vivo.

Animals↗

PubMed1999

Genomic cloning and promoter analysis of the mouse 105-kDa heat shock protein (HSP105) gene.

The 105-kDa heat shock protein (HSP105) is a member of the high-molecular-mass heat shock protein family. We have isolated and characterized the mouse HSP105 gene including about 1.2 kb of the 5'-flanking region. The mouse HSP105 gene spans about 22 kb, consisting of 18 exons separated by 17 introns. Southern blotting analysis revealed the existence of a single copy of HSP105. Primer extension analysis revealed that the transcription initiation site was located 165 bp upstream of the ATG translation initiation codon. The 5'-promoter region of the HSP105 gene contained a TATA box, a CAAT box, an inverted CAAT box, and two GC boxes. Two heat shock element (HSE) sequences were found as four nGAAn repeats at nt -64 and nt -128. Promoter analysis using deletion derivatives revealed that a minimal region which contained the two consensus HSE sequences was active in response to heat shock and also for constitutive expression of the gene.

Alternative Splicing↗

PubMed1999

High-performance liquid chromatography with peroxyoxalate chemiluminescence determination of propentofylline concentrations in rat brain microdialysate.

A high-performance liquid chromatographic determination of a neuronal cell protective compound, propentofylline [3-methyl-1-(5-oxohexyl)-7-propyl-7H-purine-2(3H),6(1H)-dione] was performed combining a microdialysis technique with peroxyoxalate chemiluminescence (PO-CL) detection. The microdialysate was subjected to a fluorescent derivatization of propentofylline with 4-(N,N-dimethylaminosulfonyl)-7-hydrazino-2,1,3-benzoxadiazole (DBD-H) without further cleanup, because the membrane used in the microdialysis excluded high-molecular-mass proteins. The proposed method showed a good linearity in the determination range of 0.031 to 1.25 ng/injection; y (microV)=4234 x (ng)- 13.43, r=0.9993 (y=peak height and x=amount of propentofylline). The very low determination limit of 0.031 ng/injection was ca. 200 times more sensitive than that of HPLC-UV determination. The HPLC-PO-CL method was applied for the first time to determine propentofylline concentration in the dialysate obtained from the rat hippocampus after a single oral administration (25 mg/kg). Propentofylline showed its maximum extracellular fluid (ECF) concentration of 125.1+/-15.1 ng/ml (mean+/-SD, n=3) at 0.33 h after administration.

Animals↗

PubMed1999

Sensitive high-performance liquid chromatographic determination with fluorescence detection of phenol and chlorophenols with 4-(4,5-diphenyl-1H-imidazol-2-yl)benzoyl chloride as a labeling reagent.

A sensitive HPLC method for the determination of phenol and chlorophenols was developed. The fluorescence labeling reaction of phenols with 4-(4,5-diphenyl-1H-imidazol-2-yl)benzoyl chloride (DIB-Cl) was completed in 30 min at 60 degrees C. The separation of DIB-derivatives of five representative phenols, i.e., phenol, o-, p-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, was achieved within 35 min with an ODS column using isocratic elution. The detection limits of these DIB derivatives at a signal-to-noise ratio (SIN) of 3 were in the range of 0.024 to 0.08 microM (0.12-0.45 pmol/20 microl injection). Twelve kinds of DIB derivatives with phenols containing mono-, di-, tri-, tetra- and penta-chlorophenol were also well separated within 208 min by changing the elution conditions. The derivatives were stable for at least for 24 h when they were placed at room temperature in the dark. The proposed method was applied to the assay of human urine samples and free and total phenol were determined. The relative standard deviations (RSDs) of the proposed method for within and between-day assay were <7.0% and <14.2%, respectively. The average concentrations of free and total phenol found in urine (n=6) were 4.3+/-2.5 and 29.5+/-14.0 microM, respectively.

Benzoates↗

PubMed1999

A comparison of tau protein in cerebrospinal fluid between corticobasal degeneration and progressive supranuclear palsy.

Many clinical and pathological discussions have been focused on the difficulty of differential diagnosis between corticobasal degeneration (CBD) and progressive supranuclear palsy (PSP) in recent years. This study was conducted to evaluate the usefulness of tau proteins in cerebrospinal fluid (CSF) for the differentiation of these two diseases. Subjects consisted of 10 patients with CBD (four males and six females with a mean age of 67.9+/-5.8 years), 12 patients with PSP (eight males and four females with a mean age of 62.6+/-5.8 years) and 36 control subjects (CTL) (16 males and 20 females with a mean age of 65.8+/-9.9 years). The CBD group included patients with probable CBD, while all the patients in the PSP group satisfied the diagnostic criteria developed by the National Institute of Neurological Disorders and Stroke and Society for PSP (NINDS-SPSP). CSF tau proteins were measured with the sandwich ELISA method (Innogenetics, Belgium). The CSF tau protein level was 320.1+/-86.5 pg/ml in the CBD group, 151.5+/-52.7 pg/ml in the PSP group and 128.7+/-91.7 pg/ml in the CTL group. Significant differences were noted in tau protein levels between the CBD group and both the PSP group (P<0.001) and the CTL group (P<0.005). We suggested that the measurement of CSF tau proteins may be useful for the differentiation between CBD and PSP.

Aged↗

PubMed1999

Calcium binding induces interaction between the N- and C-terminal domains of yeast calmodulin and modulates its overall conformation.

Calmodulin from the yeast Saccharomyces cerevisiae binds 3 mol of Ca2+ cooperatively. We report here lines of evidence supporting the intramolecular interaction between the N- and C-terminal domains which modulates the Ca2+ binding properties of yeast calmodulin. First, the sum of the Ca2+ binding curves of the N-terminal and the C-terminal half-molecule did not yield the Ca2+ binding curve of yeast calmodulin. Second, the mean residue CD of yeast calmodulin at 222 nm (-Delta epsilon222) decreased with increases in the concentration of Ca2+, whereas those of each half-molecule increased. Finally, the C2 proton of His107 in the C-terminal domain of yeast calmodulin showed three resonance peaks with increases in the concentration of Ca2+, each corresponding to the apo, the intermediate, and the Ca2+-saturated state. The intermediate peak could not be observed in the C-terminal half-molecule of yeast calmodulin. Computer simulation considering the macroscopic Ca2+ binding constants assigned this intermediate to a species consisting of the apo C-terminal domain and the N-terminal domain with at least one of the two sites occupied by Ca2+. Peptide segments spanning the defective fourth Ca2+ binding site may be involved in the interdomain interaction and the yeast-specific function of calmodulin.

Binding Sites↗

PubMed1999

Immunohistochemical expression of cytokeratins in intrahepatic cholangiocarcinoma and metastatic adenocarcinoma of the liver.

BACKGROUND AND OBJECTIVES: This study was designed to identify a difference in immunostaining that might help to distinguish between primary and metastatic liver neoplasms. METHODS: We examined immunohistochemical expression of cytokeratins (CKs) 7, 8, 19, and 20 in 12 intrahepatic cholangiocarcinomas (ICCs; 9 of the mass-forming and 3 of the infiltrating type), 25 metastatic colorectal carcinomas (MCCs), and 7 metastatic gastric carcinomas (MGCs) of the liver. RESULTS: CKs 7 and 19 were expressed in all ICCs of infiltrating type, while each was seen in 7/9 (77.8%) of mass-forming type. CK 7-positive/CK 20-negative was seen in 9/12 (75.0%) of ICCs and in none of the 25 MCCs, while CK 7-negative/CK 20-positive was seen in 1/12 (8.3%) of ICCs and 20/25 (80.0%) of MCCs. No differences were observed between MGCs and ICCs. CONCLUSIONS: These results suggest that immunohistochemical staining for both CKs 7 and 20 is useful for the differential diagnosis of ICCs and MCCs, whereas phenotypic expression of CKs appears to be different between mass-forming and infiltrating types of ICCs.

Adenocarcinoma↗