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Biomedical subjects

A Miyazaki

Publications and source records attributed to A Miyazaki.

At least 109 records · Page 6Linked to original sources
PubMed1997

Quantification of glycated hemoglobin by electrospray ionization mass spectrometry.

Glycated hemoglobin, considered to be the best index for the treatment of diabetes mellitus, was measured by electrospray ionization mass spectrometry (ESI/MS) according to the method proposed by Morris et al. at the 44th ASMS Conference on Mass Spectrometry and Allied Topics, 1996. They compared the values obtained by MS and affinity chromatography. Here, the values obtained by ESI/MS were compared with those obtained by high-performance liquid chromatography and by latex agglutination immunoassay. Whole blood samples were diluted 500 fold with 0.2% formic acid-50% acetonitrile solution and 5 microliters of the diluted solution was injected with the ESI/MS system (TSQ 7000) via a sample loop. The within-run and between-run relative standard deviations of the ratio of glycated and non-glycated beta-chain were less than 5%. The correlation coefficients between ESI/MS and conventional methods were higher than 0.96. However, considerable discrepancies were observed among methods. ESI/MS will allow reproducible measurements of glycated hemoglobin and will be useful in the quality control of HbA1c measurement by other principles and also in routine clinical laboratory tests.

Chromatography, High Pressure Liquid↗
PubMed1997

Transforming growth factor-beta1 suppresses thyrotropin-induced Na+/I- symporter messenger RNA and protein levels in FRTL-5 rat thyroid cells.

Iodide transport into the thyroid catalyzed by the Na+/I- symporter (NIS), is the first and main rate-limiting step in thyroid hormone synthesis. Recently, we have demonstrated that thyrotropin (TSH) increases NIS messenger RNA (mRNA) and protein levels, as well as iodide uptake activity. Although transforming growth factor-beta1 (TGFbeta1) is known to affect thyroid cell function, it is still unclear how TGFbeta1 regulates TSH-stimulated iodide accumulation. Therefore, the effects of TGFbeta1 on TSH-stimulated NIS mRNA and protein levels were examined in FRTL-5 rat thyroid cells by Northern and Western blot analyses, and iodide uptake was assessed. Northern blot analysis revealed that TGFbeta1 suppressed TSH-stimulated NIS mRNA levels in a dose- and time-dependent manner. Western blot analysis demonstrated that TGFbeta1 suppressed TSH-stimulated NIS protein levels. TGFbeta1 also suppressed (Bu)2 cyclic adenosine monophosphate (cAMP)- and forskolin-stimulated NIS mRNA and protein levels, indicating a role for TGFbeta1 downstream of cAMP production. As predicted, TGFbeta1 inhibited TSH-stimulated iodide uptake activity. These results suggest that the inhibitory effect of TGFbeta1 on TSH-stimulated iodide uptake is at least in part due to a suppression of NIS specific transcription. Therefore, TGFbeta1 may act as an autocrine or paracrine local modulator of thyroid hormone synthesis by influencing NIS mRNA levels in the thyroid.

Animals↗
PubMed1997

Polyarteritis nodosa associated with gastric carcinoma and hepatitis B virus infection.

Several cases of polyarteritis nodosa associated with malignant disorders have been reported, most with bone marrow-related tumors. We report polyarteritis nodosa presenting with a fever of unknown origin and muscle weakness that was complicated by advanced gastric carcinoma and hepatitis B virus-positive cirrhosis. Vasculitis was diagnosed after gastrectomy from histologic findings of arterial vasculitis on the resected gastric carcinoma. Our case is so far the second such report of polyarteritis nodosa associated with gastric cancer.

Hepatitis B↗
PubMed1997

Cytotoxicity of histocompatibility leukocyte antigen-DR8-restricted CD4 killer T cells against human autologous squamous cell carcinoma.

Although CD8+ killer T cells reacting against human autologous tumor cells have recently been studied in detail, little is known about the cytotoxic mechanism of CD4+ T cells against such tumor cells. In order to investigate this, we have established CD4+ cytotoxic T lymphocyte TcOSC-20 lines. TcOSC-20 showed selective cytotoxic activity against autologous OSC-20 cells, derived from a cancer of the tongue, in an HLA-DR-restricted fashion. HLA-DR8 (DRB1*08032) is the only DR molecule expressed on OSC-20 cells, and anti-DR8 monoclonal antibody could inhibit the cytotoxicity, suggesting that HLA-DRB1*08032 is the tumor rejection antigen-presenting molecule to TcOSC-20. The Fas ligand was expressed on TcOSC-20 lines, and its expression was induced upon mixed lymphocyte-tumor cell culture of autologous peripheral blood lymphocytes. Furthermore, the cytotoxicity of TcOSC-20 was inhibited by anti-Fas ligand antibody. These data imply that TcOSC-20 lines recognize the tumor antigenic peptide presented by HLA-DR8, and exert cytotoxicity against autologous tumor cells via a Fas-mediated cytotoxic pathway.

Antibodies, Monoclonal↗
PubMed1997

Dimethylsulfoxide maintains intercellular communication by preserving the gap junctional protein connexin32 in primary cultured hepatocyte doublets from rats.

Intercellular communication via gap junctions is one of the differentiated functions of cells. Dimethylsulfoxide (DMSO) is known to induce cell differentiation and maintain differentiated cellular functions in primary hepatocyte culture, but the mechanism of action of DMSO is unknown. Therefore, we investigated the effect of DMSO on cell-cell communication via gap junctions of hepatocyte doublets, which are differentiated cells that lose differentiated functions with time in culture. In isolated rat hepatocyte doublets, we assessed the effects of 1, 2 and 3% DMSO in culture medium on morphological changes and dye-coupling activity between pairs of cells by microinjection with fluorescent dye (Lucifer Yellow CH). The distribution of gap junction protein connexin32 (Cx32) was assessed by indirect immunofluorescence analysis and the Cx32 mRNA was detected by the reverse transcription-polymerase chain reaction method. Dimethylsulfoxide delayed the morphological change of hepatocyte doublets from a spherical to a flattened shape. Dye-coupling efficiency significantly decreased with time in culture in the control group, whereas in groups treated with 2 and 3% DMSO, dye-coupling efficiency was retained after 6 and 9 h of inoculation (P < 0.05 and P < 0.01, respectively). Analysis by indirect immunofluorescence showed few fluorescent spots for Cx32 in the control group at 9 h of incubation, whereas many punctate fluorescent spots were seen in the 3% DMSO group at 9 h of incubation. The detection of Cx32 mRNA in the 3% DMSO group was also stronger than in controls. Dimethylsulfoxide significantly maintained intercellular communication via gap junctions in primary cultured rat hepatocytes through the preservation of functional Cx32 protein, thus maintaining cell differentiation.

Animals↗
PubMed1997

Loss of Fc gamma receptor and impaired phagocytosis of polymorphonuclear leukocytes in gingival crevicular fluid.

Immunoglobulin G type II and III receptors (Fc gamma RII and Fc gamma RIII) are essential for polymorphonuclear leukocytic (PMNs) phagocytosis. Our previous study demonstrated a downregulation of Fc gamma RIII on PMNs in gingival crevicular fluid (GCF). To determine whether this receptor downregulation may contribute to the periodontal host defence borne by PMNs, we examined the correlation between Fc gamma RII and Fc gamma RIII expressions and the phagocytic capacity of GCF-PMNs. In order to verify at which level of cellular events the loss of Fc gamma R occurs, we quantified mRNA levels to assess a de novo synthesis of these receptors. GCF was collected from 21 patients with adult periodontitis by gingival crevicular washing. Autologous peripheral blood (PB) PMNs served as control. Surface expressions of Fc gamma Rs and phagocytic capacity via Fc gamma Rs were analysed by flow cytometry. The difference in Fc gamma R mRNA levels between GCF- and PB-PMNs was assessed by reverse transcription polymerase chain reaction (RT-PCR). The amplified products were visualized by agarose gel electrophoresis and the endproduct yields were quantified by computerized image-analysis. Both Fc gamma RII and Fc gamma RIII expressions and phagocytic capacity on GCF-PMNs were significantly lower than those on PB-PMNs (p < 0.001). The downregulation of Fc gamma Rs on GCF-PMNs significantly correlated with the phagocytic capacity (r = 0.66 for Fc gamma RIII, p < 0.01; r = 0.50 for Fc gamma RII, p < 0.05). The mRNA level of Fc gamma RIII of GCF-PMNs was significantly lower than that of PB-PMNs (p < 0.05). Thus, GCF-PMNs are characterized by the decreased surface expressions and mRNA levels of Fc gamma Rs, and the impaired phagocytosis.

Adult↗
PubMed1997

Relevance of immunoglobulin G Fc receptor polymorphism to recurrence of adult periodontitis in Japanese patients.

Polymorphonuclear neutrophil (PMN) phagocytic function has been shown to be impaired in some patients with periodontitis. PMN constitutively express members of two immunoglobulin G receptor (Fc gammaR) classes: Fc gammaRIIa (CD32) and Fc gammaRIIIb (CD16). Both receptors exhibit genetically determined structural and functional biallelic polymorphisms, which have been shown to influence PMN phagocytic function. In this study, we assessed the relevance of these Fc gammaR polymorphisms to susceptibility to adult periodontitis and recurrence rate. The distribution of Fc gammaRIIa and Fc gammaRIIIb genotypes of 100 Japanese patients with adult periodontitis during follow-up was compared to the distribution of genotypes in 105 race-matched healthy controls. No significant skewing of distributions of Fc gammaRIIa and Fc gammaRIIIb genotypes was observed between patients and controls. Notably, however, a significant overrepresentation of the Fc gammaRIIIb-NA2 allotype was found in patients with disease recurrence (P < 0.05; odds ratio, 4.29; 95% confidence interval, 1.19 to 16.24). Moreover, the annual rate of recurrence was significantly higher in patients with the Fc gammaRIIIb-NA2/NA2 and Fc gammaRIIIb-NA1/NA2 genotypes than in Fc gammaRIIIb-NA1/NA1 individuals (P < 0.05). Fc gammaRIIa-R/R131 individuals also exhibited higher recurrence rates, though the difference was not statistically significant (P = 0.06). These results suggest that the Fc gammaRIIIb-NA2 allotype represents a risk factor for recurrence of adult periodontitis.

Adult↗
PubMed1997

Iodide uptake and experimental 131I therapy in transplanted undifferentiated thyroid cancer cells expressing the Na+/I- symporter gene.

131I therapy is a widely accepted treatment for differentiated thyroid cancers which can accumulate iodide. We evaluated the efficiency of 131I therapy against tumors which are transfected with the Na+/I- symporter (NIS) gene. We transfected the rat NIS cDNA expression vector into malignantly transformed rat thyroid cells (FRTL-Tc) which do not concentrate iodide. The resultant cell line (Tc-rNIS) accumulated 125I 60-fold in vitro. The FRTL-Tc cells formed solid tumors after injection of cells into subcutaneous tissues of Fischer 344 rats. Tumors formed with Tc-rNIS cells accumulated up to 27.3% of total 125I administered, and concentrated 125I 11 to 27-fold in the tumors. Extracorporeal measurement of radioactivity in the tumors revealed that 125I accumulation peaked at 90 min, and decreased to half levels 6 h after the injections. To investigate the effect of 131I administration on the tumor growth, we injected Na131I 2 and 3 weeks after the transplantation of the cells. The Na131I did not change the tumor volume significantly in either the FRTL-Tc or the Tc-rNIS-induced tumors. The short (6 h) effective half life of 131I in the tumors diminished the radiation dose to the tumor cells. However, this approach may prove beneficial in the treatment of radiosensitive cancers, and could be employed diagnostically.

Animals↗
PubMed1997

Regulation by thyroid-stimulating hormone of sodium/iodide symporter gene expression and protein levels in FRTL-5 cells.

To investigate the mechanism of I- transport stimulation by TSH, we studied the effects of TSH on Na+/I- symporter (NIS) messenger RNA (mRNA) and protein levels in FRTL-5 cells and correlated these with I- transport activity. When 1 mU/ml TSH was added to quiescent FRTL-5 cells, a 12-h latency was observed before the onset of increased I- transport activity, which reached a maximum [approximately 27 times basal (5H medium) levels] at 72 h. In contrast, Northern blot analysis, using rat NIS complementary DNA as a probe, revealed that addition of TSH to these cells significantly increased NIS mRNA at 3-6 h, reaching a maximum after 24 h (approximately 5.9 times basal levels). Forskolin and (Bu)2cAMP mimicked this stimulatory effect on both the I- transport activity and mRNA levels. D-ribofranosylbenzimidazole, a transcription inhibitor, almost completely blocked TSH-induced stimulation of I- transport and NIS mRNA levels. Western blot analysis demonstrated that TSH increased NIS protein levels at 36 h, reaching a maximum at 72 h, in parallel with the kinetics of TSH-induced I- transport activity. However, it also showed that the amount of NIS protein already present in FRTL-5 cell membranes before the addition of TSH was about one third of the maximum level induced by TSH. These results indicate that stimulation of I- transport activity by TSH in thyrocytes is partly due to a rapid increase in NIS gene expression, followed by a relatively slow NIS protein synthesis. However, the existence of an abundant amount of protein in quiescent FRTL-5 cells with very low I- transport activity also suggests that this activity is controlled by another TSH-regulated factor(s).

Animals↗
PubMed1997

The first Japanese case of Hb Santa Ana, an unstable abnormal hemoglobin, identified rapidly by electrospray ionization mass spectrometry.

Two members of a family had chronic hemolytic anemia due to unstable hemoglobin. The abnormal beta-chain with a molecular weight of 16 u smaller than the normal beta-chain was found within 5 minutes by analysis using electrospray ionization mass spectrometry. The substitution of amino acid was also determined rapidly by this new strategy. The leucine at the 88th position of the normal beta-chain was substituted by proline in the hemoglobin as in Hb Santa Ana. This is the first report of a Japanese case of Hb Santa Ana; the clinical course was similar to that in the previously reported cases.

Adolescent↗
PubMed1997

[Studies of psychiatric symptoms and personality traits in the 90+ years population].

Depressive symptoms and personality traits 90+ years population were examined. Data were obtained from 33 aged people (mean 93 +/- 3.2 years old; range 90-105 years old) using the Hamilton Rating Scale for depression and a questionnaire for the evaluation of type A personality trait (devised by Dr. Maeda). Scores of > 11 in the Hamilton Rating Scale for depression were considered indicative of depression. This score was found in 39% of cases. There are four types of depressive symptoms among the 90+ years population: sleep disturbance and somatic complain type; depressive mood type; hypochodrical type; reference of ideas and obsessive-compulsive type. The usual distributions of symptoms is 43, 29, 21 and 7% respectively. According to the questionnaire for type A personality trait among the 33 cases, there were more people with type A personality (n = 18; 56%) than there were those with type B (n = 15; 44%). Of the total number of cases studied, there was a tendency high scores to be achieved items characteristic of type A personality, such as a thorough native, self-confidence and precision. On the other hand, there are also tendencies for flexibilities and "going-my-way" traints in the 90+ year population. There is a significant correlation between scores in Hamilton Rating Scale for depression and scores in the type A personality questionnaire.

Aged↗
PubMed1996

The scavenger receptor serves as a route for internalization of lysophosphatidylcholine in oxidized low density lipoprotein-induced macrophage proliferation.

We have recently demonstrated that the growth of murine macrophages is induced by oxidized low density lipoprotein (Ox-LDL) and that lysophosphatidylcholine (lyso-PC), a major phospholipid component of Ox-LDL, plays an essential role in its mitogenic effect. The present study was undertaken to further characterize the role of the macrophage scavenger receptor (MSR) in Ox-LDL-induced macrophage growth. The growth-stimulating effect of Ox-LDL on murine resident peritoneal macrophages was inhibited by maleylated bovine serum albumin (maleyl-BSA), a non-lipoprotein ligand for MSR but a poor carrier of lyso-PC, while maleyl-BSA itself failed to induce macrophage growth even in the presence of lyso-PC. Moreover, it competitively inhibited the endocytic uptake of 125I-Ox-LDL and the specific uptake of lyso-PC by MSR, whereas nonspecific lyso-PC transfer to cells was not affected. Furthermore, the Ox-LDL-induced cell growth of peritoneal macrophages obtained from MSR knockout mice was significantly weaker than that of macrophages obtained from their wild-type littermates. Our results suggest that the MSR is an important and efficient internalization pathway for lyso-PC in Ox-LDL-induced macrophage growth.

Albumins↗
PubMed1996

Lipoprotein(a) induces cell growth in rat peritoneal macrophages through inhibition of transforming growth factor-beta activation.

To elucidate the atherogenicity of lipoprotein(a) (Lp(a)), we examined its growth-stimulating activity in rat resident peritoneal macrophages. When macrophages were incubated with Lp(a), cell numbers were increased 1.5-fold as compared with control macrophages. Furthermore, apolipoprotein(a) (apo(a)), a plasminogen-like glycoprotein which is covalently attached to a low density lipoprotein-like particle (Lp(a)), also induced macrophage growth, while the growth-stimulating effect of Lp(a-) was negligible. These results suggest that apo(a) plays an active role in the mitogenic activity of Lp(a). Lp(a)-induced macrophage growth was inhibited by exogenously added active transforming growth factor-beta (TGF-beta) dose-dependently, and also by the addition of plasmin, which converts latent TGF-beta to an active form. Moreover, the amounts of endogenous active TGF-beta in the medium were significantly reduced by the incubation with Lp(a). It is evident from these results that Lp(a) induces macrophage growth by inhibiting TGF-beta activation. The capacity of Lp(a) to stimulate macrophage growth shown here could be novel atherogenic function of Lp(a).

Animals↗
PubMed1996

A new function of Ito cells in liver morphogenesis: evidence using a novel morphogenic protein, epimorphin, in vitro.

A novel mesenchymal protein, epimorphin, has been reported to play a key role in morphogenesis of fetal organs. The morphological and functional features of epimorphin in adult liver were entirely unknown. This study was performed to determine the distribution and function of this protein in the adult mouse liver. Epimorphin was detected on sinusoidal Ito cells. It played an essential role in the formation of hepatocyte spheroids which maintained differentiated function in primary culture. Therefore, Ito cells might control the differentiation of parenchymal hepatocytes in the adult liver in the pathologic condition as well as in fetal organs.

Animals↗
PubMed1996

Activation of acyl-coenzyme A:cholesterol acyltransferase activity by cholesterol is not due to altered mRNA levels in HepG2 cells.

Many studies have shown that sterols can stimulate acyl-coenzyme A:cholesterol acyltransferase (ACAT) activity in cells. To elucidate this mechanism, effects of sterol-mediated induction on both the enzyme activity of ACAT and its mRNA levels were studied in human hepatoblastoma cell line, HepG2 cells. When HepG2 cells were loaded with cholesterol and 25-hydroxycholesterol, both the whole-cell ACAT activity and the microsomal ACAT activity were increased by 85.1% and 41.3%. In contrast, cholesterol depletion of HepG2 cells with compactin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, resulted in a decrease in both the whole-cell and the microsomal ACAT activity by 46.4% and 58.3%. Under identical conditions, RT-PCR and Northern blotting analyses revealed that neither cholesterol loading nor cholesterol depletion of HepG2 cells altered the amounts of ACAT mRNA. Moreover, these treatments had no effect on the enzymatic ACAT activity determined by the reconstituted assay in which HepG2 cell homogenate had been supplemented in vitro with a saturating level of exogenous cholesterol. These results indicate that cholesterol-induced up-regulation of ACAT activity in HepG2 cells does not occur at the level of transcription, but rather at a posttranscriptional level.

Base Sequence↗
PubMed1996

Reconstituted high density lipoprotein reduces the capacity of oxidatively modified low density lipoprotein to accumulate cholesteryl esters in mouse peritoneal macrophages.

Oxidized low density lipoprotein (ox-LDL) was incubated with discoidal complexes of apolipoprotein A-I (apo A-I) and dimyristoylphosphatidylcholine (DMPC) (DMPC/apo A-I) in a cell-free system and re-isolated on Sephacryl S-400 gel filtration chromatography. Analyses of re-isolated ox-LDL showed that apo A-I was transferred from DMPC/apo A-I to ox-LDL, which accounted for 10% of the total protein of ox-LDL. Re-isolated ox-LDL also showed a 2.2-fold increase in phospholipid and a 14% decrease in cholesterol content on an apo B basis. The electrophoretic mobility of re-isolated ox-LDL was markedly reduced almost to that of native LDL. Moreover, the amounts of re-isolated ox-LDL to be degraded by mouse peritoneal macrophages as well as the capacity of re-isolated ox-LDL to accumulate cholesteryl esters (CE) in these cells were markedly reduced (60% and 80% reduction, respectively), suggesting that the ligand activity of ox-LDL for the scavenger receptor was significantly reduced upon treatment with DMPC/apo A-I. Parallel incubation of ox-LDL with free apo A-I led to a similar incorporation of apo A-I into ox-LDL. However, it had no effects on the ligand activity of ox-LDL. Thus, it is likely that the reduction in the ligand activity of ox-LDL by DMPC/apo A-I is explained by the change in the lipid moiety (mainly phospholipid) of ox-LDL. Since discoidal high density lipoprotein (HDL) is known to occur in vivo, this phenomenon might explain one of the anti-atherogenic functions of HDL.

Animals↗