Biomedical subjects

Y Nakamaru

Publications and source records attributed to Y Nakamaru.

At least 19 recordsLinked to original sources

PubMed2004

Immunoregulatory defects of V alpha 24V+ beta 11+ NKT cells in development of Wegener's granulomatosis and relapsing polychondritis.

The frequency of either CD4(-)8(-) (double negative; DN) or CD4(+) V alpha 24(+)V beta 11(+) NKT cells, the expression of CD1d and the binding of CD1d-tetramer loaded with alpha-galactosylceramide (alpha-GalCer) to NKT cells were analysed in peripheral blood mononuclear cells (PBMCs) of patients with Wegener's granulomatosis (WG), relapsing polychondritis (RP) and healthy subjects (HS). DN and CD4(+) V alpha 24(+)V beta 11(+) NKT cells as well as CD1d-alpha-GalCer tetramer-positive NKT cells, were significantly decreased in number in both WG and RP patients compared to those from HS. When cytokine profiles were analysed in these PBMCs upon stimulation with phorbol ester and calcium ionophore, CD4(+) T cells from patients with WG and RP exhibited a Th1 bias, whereas CD4(+) NKT cells from WG patients in remission showed a Th2 bias. These findings suggest that NKT cells (especially CD4(+) NKT cells) play a regulatory role in Th1 autoimmunity in patients with WG and RP. The reduction in NKT cell counts appears to be associated with the low responsiveness to alpha-GalCer. The dysfunction of NKT cells to recognize ligands such as alpha-GalCer may also contribute to the defects observed in NKT cells from WG and RP patients.

Aged↗

PubMed2001

Relapsing polychondritis: a report of eight cases.

OBJECTIVE: To investigate clinical manifestations of relapsing polychondritis and to clarify the significance of type II collagen antibody in the disease. METHODS: Clinical manifestations and antibody titers were examined in eight cases of relapsing polychondritis which had been treated at Otolaryngology Department, Hokkaido University during the eight years from 1991 to 1998. Anti-type II collagen antibody titer was measured by ELISA method. RESULTS: The most frequent symptom was auricular chondritis; it was seen in 88% (7/8) of the cases. Ocular symptom, nasal chondritis, arthritis, respiratory tract chondritis, and audio-vestibular symptom were also common in the cases. Compared with previous reports, no difference was recognized in the manifestation frequency. Considering none of the samples from the controls was positive for anti-type II collagen antibody, two samples from the disease group were positive. The antibody positive rate was 25% (2/8). CONCLUSION: Though the measurement of type II collagen antibody titer is not a decisive factor for detection of relapsing polychondritis, it is useful as one of the complementary factors for the diagnosis, since there is no specific test for this disease.

Adolescent↗

PubMed2001

Correlation between the levels of circulating adhesion molecules and PR3-ANCA in Wegener's granulomatosis.

OBJECTIVE: The adhesion of neutrophils to the vascular endothelial cells appears to be important for the pathogenesis of vasculitis in Wegener's granulomatosis (WG). To determine the pathological significance of the neutrophil adhesion, we have examined and evaluated the relationships between the levels of adhesion molecules and proteinase-3 anti-neutrophil cytoplasmic antibodies (PR3-ANCA), and between the levels of TNF-alpha and disease activities in WG. METHODS: sELAM-1 and sICAM-1 in sera from WG and healthy donors were detected by ELISA. SLex and LFA-1 on neutrophils were detected by flow cytometry. RESULTS: The level of sICAM-1 was significantly higher in active WG than in inactive WG, tending to reflect individual disease activities. There was no difference in the level of sELAM-1 between WG patients and healthy donors. CONCLUSION: Our study suggests that the adhesion of neutrophils to the vascular endothelium is significant for the pathogenesis of the vasculitis in WG.

Adult↗

PubMed2001

Immunological hyperresponsiveness in HTLV-I LTR-env-pX transgenic rats: a prototype animal model for collagen vascular and HTLV-I-related inflammatory diseases.

We have earlier reported that diverse collagen vascular diseases, including arthritis, arteritis, thrombosis, myocarditis, myositis, sialo-/dacryoadenitis and dermatitis develop with the advent of autoantibodies in transgenic rats carrying the LTR-env-pX gene of human T lymphocyte virus type I (LTR-env-pX rats). To clarify the pathogenesis of these collagen vascular diseases, immunological features of LTR-env-pX rats were examined. In LTR-env-pX rats affected with these diseases, expression of CD80/86 on both tissue-infiltrating and peripheral T cells increased, compared with findings in non-transgenic rats with experimental inflammatory diseases. CD80/86 was also upregulated on peripheral T cells in LTR-env-pX rats prior to the development of diseases. Lymphocytes from LTR-env-pX rats showed an increase in autologous proliferation and were hyperreactive against several mitogens, including concanavalin A, immobilized anti-CD3 antibodies, and superantigens in vitro. Antigen-specific immune response was also enhanced in LTR-env-pX rats. The collective evidence indicates that lymphocytes of LTR-env-pX rats constitutively express surface molecules related to T cell activation and are immunologically hyperresponsive. Bone marrow cell transfer from LTR-env-pX rats to lethally irradiated non-transgenic rats revealed that these immunologically pre-activated and hyperresponsive lymphocytes play a critical role in the pathogenesis of several collagen vascular diseases, especially of dermatitis in LTR-env-pX rats.

Animals↗

PubMed2001

[Nasal allergies in Kushiro].

A clinical study of 107 patients with nasal allergies who were treated at Kushiro General Hospital between April 1998 and March 2000 was performed. Radioallergosorbent tests (RAST), X-rays, and nasal smears for the detection of eosinophilia were performed to obtain a diagnosis of nasal allergy. The patients (50 males, 57 females) ranged in age from 3 to 71 years. The RAST was positive for timothy in 22.4% of the patients, 14.0% for birch and 12.1% for mugwort. The most common pollinosis allergen in the Kushiro area was grass pollen. Other pollinosis allergens were birch pollen and mugwort pollen. We measured the daily count of dispersed birch pollen and timothy pollen in Kushiro and Sapporo. Birch pollen and timothy pollen was dispersed earlier in Kushiro than in Sapporo. Nasal allergies in the Kushiro area appear to be related to local characteristics, such as climate and geographical features.

Adolescent↗

PubMed2000

Identical independent sites for dye ligand on bovine serum albumin demonstrated by multivariate analysis.

The most fundamental parameters concerning an interaction between a ligand and a protein are equilibrium constants and the number of binding sites. The Scatchard plot has for a long time been widely used to obtain those parameters. However, controversy in 1982-1983 over the reliability of this plot (the graphical estimation of the number of identical independent sites from the x-intercept) indicated that some methodologies other than the Scatchard plot are expected. Over the past decade, we have developed a method for applying multivariate analysis to the problem of determining spectral features of a ligand associated with a protein molecule. In principle, this method is based mainly on the computer-assisted adjustment of dissociation constants to an assumed reaction model. We discovered in this process that an n-parameter, introduced into an equation for calculating the amount of dye ligand bound to a protein, coincided with the number of identical independent sites, under a certain condition in principal factor analysis calculation. In this study, we established a new methodology for determining the number of identical independent sites using synthesized spectral series, and we then applied this method to a simple reaction system composed of bovine serum albumin (BSA) and bromocresol purple (BCP) anions. BSA was found to have two identical independent sites for BCP anions at pH 8.8.

Animals↗

PubMed2000

A chemometric approach to the estimation of the absorption spectra of dye probe merocyanine 540 in aqueous and phospholipid environments.

Merocyanine 540 (MC540) is a widely used dye probe for membranous environments. However, fundamental knowledge of the spectral features of this dye in aqueous and hydrophobic environments is still lacking. Such knowledge is important because biomembranes involve a hydrophobic environment surrounded by a hydrophilic environment. Because many investigations so far have been performed based on indistinct spectral estimations, the interpretation of the data obtained using this dye as a fluorescent transmembrane probe remains controversial. In order to determine the exact spectra in both aqueous and hydrophobic environments, we adopted principal factor analysis (PFA), a method of multivariate analysis. The PFA method can also determine the number of molecular species present in the reaction mixture, which is three in pure water and two in phospholipid suspension. Two of the species in both water and phospholipid suspension were the monomer and dimer. The third species in water was the trimer, but its amount was so small at 10 microM MC540 solution that the spectral data in water can be approximated neglecting this molecular species. The monomer spectrum changed its form markedly with a bathochromic shift when transferred from the water to phospholipid environment, whereas the dimer remained similar in its shape except for a remarkable red shift. In water, the dissociation constants, K(1) and K(2), for the assumed stacking-model reactions, M+M <--> M(2) and M+M(2) <--> M(3), were 3.1 x 10(-4) M and 5.7 x 10(-4) M, respectively. In the phospholipid environment, the dissociation constant K* for the assumed stacking-model reaction, M(*)+M(*) <--> *M(2), was 1.9x10(-5)M. The fluorescent intensities of MC540 were also measured in both water and phospholipid environments. A comparison based on the absorption and fluorescence spectra suggested that the temporal increase in the amount of the monomer on the excitable membrane contributes to the fluorescent intensity change observed in the transmembrane potential change.

Fluorescent Dyes↗

PubMed1999

Mechanosensitive channel functions to alleviate the cell lysis of marine bacterium, Vibrio alginolyticus, by osmotic downshock.

The mechanosensitive channel with large conductance of Escherichia coli is the first to be cloned among stretch-activated channels. Although its activity was characterized by a patch clamp method, a physiological role of the channel has not been proved. The marine bacterium, Vibrio alginolyticus, is sensitive to osmotic stress and cell lysis occurs under osmotic downshock. We introduced an mscL gene into Vibrio alginolyticus, and the mechanosensitive channel with large conductance functions was found to alleviate cell lysis by osmotic downshock. This is the first report to show a physiological role of the mechanosensitive channel with large conductance.

Bacterial Proteins↗

PubMed1999

Etidronate (EHDP) inhibits osteoclastic-bone resorption, promotes apoptosis and disrupts actin rings in isolate-mature osteoclasts.

Bisphosphonates, therapeutic reagents against tumoral bone diseases (Paget's disease or osteoporosis), are potent inhibitors of bone resorption. The mechanisms by which they directly act on mature osteoclasts remain unclear. Using a recently developed technique for isolation of highly purified mammalian mature osteoclasts, we demonstrated that etidronate [ethane-1-hydroxy-1,1-diphosphonate (EHDP), 1-hydroxy-1,1-ethylidenebisphosphonate], inhibited directly osteoclastic bone-resorbing activity by pit assay. In addition, EHDP also directly induced apoptosis and disrupted actin rings in osteoclasts. The data support previous data on non-purified osteoclasts and results in vivo.

Actins↗

PubMed1997

Multivariate analysis of the association of bromocresol purple anion with bovine serum albumin.

The interaction of bromocresol purple (BCP) anions with bovine serum albumin (BSA) was investigated by principal factor analysis method, and reaction model, the number of molecular species and spectra of each component present in the reaction mixture were determined. The number of molecular species concerning the absorption intensity was three, including free BCP anion. Most part of the spectral change could be explained by the monomer binding of bromocresol purple anion (D) to serum albumin (P), a simple one step equilibrium, P + D = PD. A second type of association of BCP anions with serum albumin was also present, though in a small amount. Of six models tested which consisted of three or four molecular species, the sequential two step reaction model, P = PD = PD2, was the best model to explain the spectral data, and an existence of BCP anions as a dimer on the serum albumin was demonstrated. The dissociation constants were estimated at K1 = 1.6 x 10(-6) M for the first step and K2 = 1.2 x 10(-5) M for the second step.

Bromcresol Purple↗

PubMed1997

Estrogen inhibits bone resorption by directly inducing apoptosis of the bone-resorbing osteoclasts.

Estrogen deficiency causes bone loss, which can be prevented by estrogen replacement therapy. Using a recently developed technique for isolation of highly purified mammalian osteoclasts, we showed that 17 beta-estradiol (E2) was able to directly inhibit osteoclastic bone resorption. At concentrations effective for inhibiting bone resorption, E2 also directly induced osteoclast apoptosis in a dose- and time-dependent manner. ICI164,384 and tamoxifen, as pure and partial antagonists, respectively, completely or partially blocked the effect of E2 on both inhibition of osteoclastic bone resorption and induction of osteoclast apoptosis. These data suggest that the protective effects of estrogen against postmenopausal osteoporosis are mediated in part by the direct induction of apoptosis of the bone-resorbing osteoclasts by an estrogen receptor- mediated mechanism.

Animals↗

PubMed1997

Interleukin-1alpha regulates Thy-1 expression on rat vascular endothelial cells.

We recently reported that Thy-1, a surface molecule induced on the rat endothelium, regulates vascular permeability at sites of inflammation. Although the rat inferior vena cava (IVC) did not express Thy-1 in vivo, cultured endothelial cells from the IVC did express Thy-1, thereby suggesting that the expression was acquired during cultivation of the cells in vitro, possibly by autoactivation by cytokine-like substances. Interleukin (IL)-1alpha but not tumor necrosis factor (TNF)-alpha or interferon (IFN)-gamma was detected in culture supernatants of rat endothelial cells (REC) by ELISA. The production of IL-1alpha by REC was augmented by exogenously added IL-1alpha, thereby implying the presence of autocrine regulation by IL-1alpha. The unaltered expression of Thy-1 by exogenously added IL-1alpha suggests that Thy-1 expression on REC had already been maximally induced by autologous cytokines; the expression of Thy-1 on REC was lowered by inhibiting protein kinase C and by depleting IL-1alpha activity from culture supernatants. Although cytokine-like regulators, other than IL-1alpha, TNF-alpha, or IFN-gamma, produced by REC may also modulate the expression of Thy-1, it is at least in part mediated by IL-1alpha in vitro. Moreover, Thy-1 expression was induced on rat vascular endothelium at the subcutis where recombinant IL-1alpha was injected. The evidence indicates that IL-1alpha functions as one regulator responsible for the induction of Thy-1 on REC, in vitro as well as in vivo.

Animals↗

PubMed1997

A wide spectrum of collagen vascular and autoimmune diseases in transgenic rats carrying the env-pX gene of human T lymphocyte virus type I.

To investigate the pathogenesis of human T lymphocyte virus type I (HTLV-I)- related diseases, the env-pX gene of HTLV-I was introduced into the germline of inbred Wistar-King-Aptekman-Hokudai rats. A wide spectrum of collagen vascular diseases was evident in the transgenic rats, including chronic destructive arthritis similar to rheumatoid arthritis, necrotizing arteritis mimicking polyarteritis nodosa, polymyositis, myocarditis, dermatitis, and chronic sialoadenitis and dacryoadenitis resembling Sjögren's syndrome in humans. Thymic atrophy with the depletion of CD4 and CD8 double-positive thymocytes was also observed. In these animals, a number of autoantibodies, including high titers of rheumatoid factor, were present in the serum. We propose that the HTLV-I env-pX gene region may play a pathogenetic role in the development of collagen vascular and autoimmune diseases associated with autoimmune phenomenon.

Animals↗

PubMed1997

Down-regulation of gap junctional intercellular communication between osteoblastic MC3T3-E1 cells by basic fibroblast growth factor and a phorbol ester (12-O-tetradecanoylphorbol-13-acetate).

To address the relation between osteoblast growth and cell-to-cell communication, we examined the effects of basic fibroblast growth factor (bFGF) and 12-O-tetradecanoylphorbol-13-acetate (TPA), both potent stimulators of osteoblastic proliferation, on gap junctional intercellular communication between osteoblastic MC3T3-E1 cells. The level of intercellular communication was estimated by a photobleaching method. TPA inhibited the degree of intercellular communication in two different time-dependent manners. The early (< 1 h) inhibition by TPA was consistent with an increase in the phosphorylation of connexin 43 (Cx43). The later inhibition was caused by reduction in the total amount of Cx43 on the plasma membrane, due to the decrease in the level of Cx43 transcripts. These qualitative and quantitative modulations by TPA were inhibited by a selective inhibitor of protein kinase C, GF109203X. bFGF also attenuated the gap junctional intercellular communication. However, short exposure (< 5 h) to bFGF did not affect the communication. The fact that the growth factor immediately stimulated the phosphorylation of Cx43 indicates that the phosphorylation site(s) affected by bFGF was not involved in the inhibition of communication. The decrease in the intercellular communication level was detected by the longer exposure (> 8 h) to bFGF and paralleled the decline in the Cx-mRNA level. This inhibitory effect of bFGF was abolished by the addition of a tyrosine kinase inhibitor, herbimycin A. Thus, gap junctional intercellular communication between osteoblasts was down-regulated by osteoblastic mitogens through different mechanisms of the modulation of Cx43.

3T3 Cells↗

PubMed1997

Models of HTLV-I-induced diseases. Infectious transmission of HTLV-I in inbred rats and HTVL-I env-pX transgenic rats.

To examine the pathogenic roles of HTLV-I in HTLV-I-induced diseases, we developed two models; namely HTLV-I carrier rats and HTLV-I env-pX transgenic rats. Among life long HTLV-I carriers in seven rat strains, only WKAH rats with the RT1k haplotype developed chronic progressive myeloneuropathy, resembling HAM/TSP clinically and histologically in humans, designated as HAM rat disease and after long incubation periods. Apoptosis of myelin forming cells, oligodendrocytes and Schwann cells associated with HTLV-I infection appears to be the primary cause of HAM rat disease. Local activation of the pX gene and TNF alpha gene was evident in these rats. WKAH rats transgenic for HTLV-I env-pX gene were established and at age 5 weeks, swelling of the bilateral ankle joints began to develop and histological features of the affected joints resembled findings in cases of rheumatoid arthritis (RA): high-titers of rheumatoid factors were present in these rats. A series of vascular collagen diseases such as polyarteritis nodosa-like angiitis, polymyositis, myocarditis, and Sjögren's syndrome-like sialodenitis together with RA were present, even in one individual animal. These transgenic rats as well as HAM rats appear to be suitable animal models for elucidating pathogenic mechanisms implicated in HTLV-I-induced diseases and also various demyelinating vascular collagen diseases of unknown etiology.

Animals↗

PubMed1997

[Immunological analysis of HTLV-I env-pX transgenic rat with various collagen vascular diseases].

Human T lymphocyte virus type-I (HTLV-I) is an etiologic agent of not only adult T cell leukemia but also HTLV-I associated myelopathy/tropical spastic paraparesis, HTLV-I associated arthropathy and other immunological disorders, such as Sjögren syndrome, dermatitis, polymyositis, and uveitis. We recently reported that a wide spectrum of collagen vascular diseases, including inflammatory arthropathy resembling rheumatoid arthritis, myocarditis, dermatitis, necrotizing arteritis, myositis and sialoadenitis similar to Sjögren's syndrome, developed in the transgenic rat carrying HTLV-I env-pX region under the control of its own long terminal repeat (env-pX rat). To investigate the pathogenetic role of these diseases, cell surface molecules and functions of lymphocytes from env-pX rats were examined in this study. In env-pX rats with diseases, not only infiltrating lymphocytes in the inflammatory sites but also peripheral lymphocytes expressed a large number of co-stimulating molecules such as CD80/86 and ICAM-1, compared with those of normal rats or rats with adjuvant-induced arthritis or myosin-induced myocarditis. Moreover, the expression of CD80/86 and ICAM-1 was already up-regulated on the surface of peripheral lymphocytes in env-pX rat before developing any diseases. Lymphocytes, taken from env-pX rats immunized with myosin in vivo, showed significantly higher cellular response against myosin in vitro than those of normal rats. Lymphocytes from env-pX rats also showed the hyper-reactivity to the stimulation by super-antigens, but no significant difference of the usage of T cell receptor V beta was found compared with those of normal rats. These results suggest that the env-pX transgene may induce the high expression of CD80/86 and ICAM-1 on the lymphocytes and the resulting hyper-immune responsiveness in env-pX rats.

Animals↗

PubMed1996

Mammalian mature osteoclasts as estrogen target cells.

The decrease in estrogen levels that follows the onset of menopause causes rapid bone loss, resulting in osteoporosis. However, the mechanism by which this occurs remains unclear, especially concerning the regulation of osteoclasts, i.e. the bone-resorbing cells. Using a pit assay involving isolated mature osteoclasts from rabbit long bones, we found that estrogen inhibited the bone-resorbing activity in a dose- and time-dependent manner. Furthermore, we clarified by Northern analysis that estrogen down-regulated the mRNA levels of cathepsin K/OC-2 and that putative estrogen receptor (ER) mRNA was expressed in these osteoclasts. Moreover, other sizes of mRNAs that hybridized with ER cDNA probe were found in these cells. Our results suggest that osteoclasts may be indeed target cells for estrogen and that estrogen might regulate a part of bone metabolism through osteoclasts.

Animals↗

PubMed1996

Vitamin K2 inhibits osteoclastic bone resorption by inducing osteoclast apoptosis.

In contrast to vitamin K1(VK1), vitamin K2(VK2) inhibited osteoclastic bone resorption by unfractionated bone cells and isolated osteoclasts. To investigate the mechanism of inhibition of osteoclastic bone resorption by VK2, we examined the effect of this vitamin on osteoclast apoptosis using a DNA-binding fluorescent dye, Hoechst 33258. In unfractionated bone cells and isolated osteoclasts on dentin slices, we first demonstrated that VK2 induced osteoclast apoptosis, but VK1 did not. Moreover, cycloheximide inhibited VK2-induced osteoclast apoptosis. These results suggest the possibility that VK2 inhibits osteoclastic bone resorption by targeting osteoclasts to undergo apoptosis, which leads to cell death.

Animals↗