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Biomedical subjects

Y Suzaki

Publications and source records attributed to Y Suzaki.

At least 19 recordsLinked to original sources
PubMed2001

Comparison of neuropathogenicity of poliovirus type 3 in transgenic mice bearing the poliovirus receptor gene and cynomolgus monkeys.

To clarify the similarities of poliovirus infection in cynomolgus monkeys and transgenic mice bearing the poliovirus receptor, TgPVR21, we compared the pathological changes of these animals following intraspinal inoculation of two strains of poliovirus type 3 using immunohistochemical detection of the capsid antigen. All of the monkeys inoculated with 10(6) TCID(50) viruses showed flaccid paralysis 2 or 3 days post-inoculation (p.i.). TgPVR21 mice showed paralysis starting from 2 to 3 days p.i. Histologically, neurons having pyknotic nuclei and eosinophilic cytoplasm and neuronophagia were characteristically observed in both animals, but central chromatolysis was not observed in infected TgPVR21. The median lesion scores in the monkeys and TgPVR21 were well correlated, though the distribution of poliovirus-infected lesions in the central nervous system was different. In both animals the motor neurons and the brainstem nuclei responsible for flaccid paralysis were infected by the virus, while the cerebral cortex and thalamus were infected in the monkeys but not in TgPVR21. These results confirmed the reliability of neurovirulence tests using TgPVR21 as a substitute for monkeys, in respect to the spinal and brainstem lesions of poliovirus type 3.

Animals↗
PubMed2001

Quercetin inhibits Shc- and phosphatidylinositol 3-kinase-mediated c-Jun N-terminal kinase activation by angiotensin II in cultured rat aortic smooth muscle cells.

Angiotensin II (Ang II) induces vascular smooth muscle cell (VSMC) hypertrophy, which results in various cardiovascular diseases. Ang II-induced cellular events have been implicated, in part, in the activation of mitogen-activated protein (MAP) kinases. Although it has been proposed that daily intake of bioflavonoids belonging to polyphenols reduces the incidence of ischemic heart diseases (known as "French paradox"), the precise mechanisms of efficacy have not been elucidated. Thus, we hypothesized that bioflavonoids may affect Ang II-induced MAP kinase activation in cultured rat aortic smooth muscle cells (RASMC). Our findings showed that Ang II stimulated rapid and significant activation of extracellular signal-regulated kinase (ERK) 1/2, c-Jun N-terminal kinase (JNK), and p38 in RASMC. Ang II-induced JNK activation was inhibited by 3,3',4',5,7-pentahydroxyflavone (quercetin), a major bioflavonoid in foods of plant origin, whereas ERK1/2 and p38 activation by Ang II were not affected by quercetin. Ang II caused a rapid tyrosine phosphorylation of Src homology and collagen (Shc), which was inhibited by quercetin. Quercetin also inhibited Ang II-induced Shc.p85 association and subsequent activation of phosphatidylinositol 3-kinase (PI3-K)/Akt pathway in RASMC. Furthermore, LY294002, a PI3-K inhibitor and a quercetin derivative, inhibited Ang II-induced JNK activation as well as Akt phosphorylation. Finally, Ang II-induced [(3)H]leucine incorporation was abolished by both quercetin and LY294002. These findings suggest that the preventing effect of quercetin on Ang II-induced VSMC hypertrophy are attributable, in part, to its inhibitory effect on Shc- and PI3-K-dependent JNK activation in VSMC. Thus, inhibition of JNK by quercetin may imply its usefulness for the treatment of cardiovascular diseases relevant to VSMC growth.

Angiotensin II↗
PubMed2000

Effect of endothelin-1(1-31) on p38 mitogen-activated protein kinase in cultured human mesangial cells.

It was reported that human chymase cleaves big endothelins (ETs) at the Tyr31-Gly32 bond and produces 31-amino acid ETs(1-31). In this study, we investigated the effect of ET-1(1-31) on p38 mitogen-activated protein kinase (p38-MAPK) activity in human mesangial cells (HMCs). By measuring the kinase activity, we demonstrated that ET-1 (1-31) activated the p38-MAPK dose-dependently (10(-9) M to 10(-7) M), which was inhibited by SB203580. The p38-MAPK activation induced by ET-1(1-31) peaked at 10 minutes. BQ123 almost abolished ET-1(1-31)-induced p38-MAPK activation, whereas BQ788 failed to inhibit it. These findings suggest that the stimulatory effect of ET-1(1-31) on p38-MAPK activation is mediated through ET(A) or ET(A)-like receptor. In conclusion, ET-1(1-31) induced increase in p38-MAPK activation in cultured HMCs.

Blotting, Western↗
PubMed2000

Induction of CD95 ligand expression on T lymphocytes and B lymphocytes and its contribution to apoptosis of CD95-up-regulated CD4+ T lymphocytes in macaques by infection with a pathogenic simian/human immunodeficiency virus.

Using an established SIV/HIV-C2/1-infected cynomolgus monkey model displaying stable CD4+ T cell depletion, the kinetics of apoptosis and the levels of expression of CD95 membrane-associated CD95L on lymphocytes were investigated to test the involvement of the CD95/CD95L system in CD4+ T lymphocyte loss in vivo. Rapid depletion of CD4+ T cells occurred up to 2 weeks after infection, with chronic CD4+ T lymphopenia thereafter. During the initial CD4+ T cell loss, which was accompanied by viraemia, about 90% of the peripheral CD4+ T cell subset underwent spontaneous apoptotic cell death during 24 h of culture. Increased expression of CD95 was observed on both CD4+ and CD8+ T cell subsets, with CD95 expression on CD8+ cells declining rapidly, but high CD95 expression being maintained on CD4+ cells. Since CD95L was expressed on CD8+ T cells, B cells and to a lesser extent on CD4+ T cells, this suggests that CD95-mediated apoptosis might be controlled in an autocrine/paracrine fashion.

Animals↗
PubMed2000

Recovery of pathogenic measles virus from cloned cDNA.

Reverse genetics technology so far established for measles virus (MeV) is based on the Edmonston strain, which was isolated several decades ago, has been passaged in nonlymphoid cell lines, and is no longer pathogenic in monkey models. On the other hand, MeVs isolated and passaged in the Epstein-Barr virus-transformed marmoset B-lymphoblastoid cell line B95a would retain their original pathogenicity (F. Kobune et al., J. Virol. 64:700-705, 1990). Here we have developed MeV reverse genetics systems based on the highly pathogenic IC-B strain isolated in B95a cells. Infectious viruses were successfully recovered from the cloned cDNA of IC-B strain by two different approaches. One was simple cotransfection of B95a cells, with three plasmids each encoding the nucleocapsid (N), phospho (P), or large (L) protein, respectively, and their expression was driven by the bacteriophage T7 RNA polymerase supplied by coinfecting recombinant vaccinia virus vTF7-3. The second approach was transfection with the L-encoding plasmid of a helper cell line constitutively expressing the MeV N and P proteins and the T7 polymerase (F. Radecke et al., EMBO J. 14:5773-5784, 1995) on which B95a cells were overlaid. Virus clones recovered by both methods possessed RNA genomes identical to that of the parental IC-B strain and were indistinguishable from the IC-B strain with respect to growth phenotypes in vitro and the clinical course and histopathology of experimentally infected cynomolgus monkeys. Thus, the systems developed here could be useful for studying viral gene functions in the context of the natural course of MeV pathogenesis.

Animals↗
PubMed2000

Anti-tetanus toxoid antibody production and protection against lethal doses of tetanus toxin in hu-PBL-SCID mice.

BACKGROUND: In this study, severe combined immunodeficiency (SCID) mice, which permit the survival of lymphoid cells of human origin, were used to study the human anti-tetanus immune response. METHODS: Human peripheral blood lymphocytes (hu-PBL) obtained from 88 healthy donors (aged from 18 to 62) were transplanted into SCID mice, and anti-tetanus toxoid (Ttd) antibody production and protection against lethal doses of tetanus toxin (Ttx) were investigated in the hu-PBL-SCID mice. RESULTS: The transfer of human PBL evoked significant human anti-Ttd IgG antibody production for 37.5% of the donors. After in vivo immunization, the percentage of donors with PBL exhibiting positive anti-TtD IgG production in the mice increased to 54.5%. Mean anti-Ttd IgG levels in the sera were also significantly elevated in response to immunization. The mean IgG titer for the mice injected with PBL from donors under the age of 40 was significantly higher than that of the mice injected with PBL from donors aged 40 or older. Four weeks after the cell transfer, the mice were challenged with Ttx. The induction of protection against Ttx challenge was observed mostly in mice with PBL transferred from donors under the age of 40. In vivo immunization in SCID mice with Ttd increased the number of cases of resistance to Ttx. CONCLUSIONS: These results suggest that hu-PBL-SCID mice might serve as a tool for predicting the protective ability against pathogens in PBL donors and also for evaluating vaccine efficacy.

Adolescent↗
PubMed2000

Effect of endothelin-1 (1-31) on human mesangial cell proliferation.

It was previously found that human chymase cleaves big endothelins (ETs) at the Tyr31-Gly32 bond and produces 31-amino acid ETs (1-31). In the present study, human plasma concentrations of ET-1 (1-31) and ET-1 were examined and the effect of synthetic ET-1 (1-31) on the proliferation of cultured human mesangial cells (HMCs) was investigated. The proliferative effect of ET-1 (1-31) was evaluated from the [3H]-thymidine uptake. The activity of extracellular signal-regulated kinase (ERK) and DNA binding activity of activator protein-1 were determined by using an in-gel kinase assay and gel mobility shift assay, respectively. Immunoreactive ET-1 (1-31) was detectable in plasma, but the level was slightly lower than that of ET-1. ET-1 (1-31) increased [3H]-thymidine incorporation in HMCs to a degree similar to that induced by ET-1. ET-1 (1-31) also activated ERK1/2. Inhibition of protein kinase C and ERK kinase caused a reduction of ET-1 (1-31)-induced ERK1/2 activation. The ERK1/2 activation was followed by an increase in transcription factor activator protein-1 DNA binding activity. These findings suggest that ET-1 (1-31) is a bioactive peptide in humans and ET-1 (1-31) itself stimulates HMC proliferation.

Adult↗
PubMed1999

Concentrations of C-reactive protein in normal monkeys (Macaca irus) and in monkeys inoculated with Bordetella bronchiseptica R-5 and measles virus.

The concentrations of C-reactive protein (CRP) in serum from normal crab-eating monkeys (Macaca irus) were measured by means of a monkey-specific turbidimetric immunoassay (TIA), and the changes in the serum CRP concentrations in crab-eating monkeys inoculated with Bordetella bronchiseptica R-5 and measles virus (Ichinose or NK 3 strain) were also examined. The CRP concentrations in sera from 54 normal crab-eating monkeys ranged from 0 to 8.3 microg/ml (mean 2.2 +/- 1.9). No significant difference was found in the CRP concentrations between males and females (p > 0.05). The concentrations of CRP in the sera from four crab-eating monkeys inoculated intrabronchially with 10(9) live B. bronchiseptica increased gradually to a peak at 2 days after inoculation. The peak concentrations of CRP were from 102.4 to 313.2 microg/ml, 54-96 times the preinoculative values of 1.9-5.6 microg/ml. When the same four crab-eating monkeys were inoculated intrabronchially with measles virus 34 days after inoculation of B. bronchiseptica, the serum CRP concentrations did not increase. Monitoring of CRP is useful for assessing monkeys with acute B. bronchiseptica infection and will probably be of value in the diagnosis of other bacterial infections.

Animals↗
PubMed1999

A highly pathogenic simian/human immunodeficiency virus with genetic changes in cynomolgus monkey.

A highly pathogenic simian/human immunodeficiency virus (SHIV), designated C2/1, was obtained by serum passages in cynomolgus monkeys of p-SHIV, an SHIV strain that contains the env gene of pathogenic human immunodeficiency virus type 1 89.6. CD4+ lymphocyte depletion was induced within 1 week of the SHIV-C2/1 infection in peripheral blood as well as in various lymphoid organs in all the animals tested, with symptoms of diarrhoea and no increase in body weight, followed by intense viraemia. Serum antibody against Env protein was detected from 4 weeks after the virus infection, while the anti-Gag antibody response was absent in the SHIV-C2/1-infected animals. In contrast, both anti-Gag and anti-Env antibody responses were present in animals infected with p-SHIV or the non-pathogenic SHIV-MN. Sequencing of the env gene of isolates of SHIV-C strains showed conserved amino acid changes in the Env C2 and V3 regions that included changes to negatively charged amino acids, in the cytoplasmic region of gp41 that included a 42 amino acid deletion, and in the Nef protein. The pathogenic SHIV-C2/1-monkey model suggests that virus-specific pathogenicity in SHIV infection may be associated with the absence of anti-Gag antibody responses in animals and may be caused by genetic changes during serum passage in vivo.

Amino Acid Sequence↗
PubMed1999

Antigen-specific, IgE-selective unresponsiveness induced by antigen-liposome conjugates. Comparison of four different conjugation methods for the coupling of antigen to liposome.

BACKGROUND: We have previously reported that ovalbumin (OVA) coupled with liposome via glutaraldehyde (GA) induced OVA-specific- and IgE-selective unresponsiveness in mice. METHODS: In this study, OVA-liposome conjugates were made using four different coupling protocols: via GA, N-(6-maleimidocaproyloxy) succinimide (EMCS), disuccinimidyl suberate (DSS) and N-succimidyl-3(2-pyridyldithio)propionate (SPDP) and the induction of antigen-specific IgG and IgE antibody production was investigated for each. In addition, antigen-specific cytokine production by spleen cells of mice immunized either with OVA-liposome or with OVA adsorbed with aluminum hydroxide was investigated. RESULTS: OVA-liposome conjugates coupled via GA or DSS did not induce anti-OVA IgE antibody production but induced substantial anti-OVA IgG antibody production. On the other hand, the induction of anti-OVA IgE unresponsiveness by OVA-liposome conjugates coupled via EMCS or SPDP was incomplete. The amount of interleukin 4 (IL-4) produced by spleen cells stimulated in vitro with OVA correlated well with anti-OVA IgE antibody production in donor mice. However, the production of no other cytokine, i.e., IL-2, IL-5, IL-10 or interferon-gamma, was correlated with in vivo IgE antibody production. CONCLUSION: OVA-liposome coupled via GA or DSS induced complete suppression of anti-OVA IgE production. The results in this study further suggest that the regulation of IgE antibody production does not necessarily correlate with so-called Th1 cytokine production.

Animals↗
PubMed1999

[Multiple primary cancers of oral cavity and pharynx].

Multiple primary cancers were found in 23 of 68 patients (34%) with an index cancer in the oral cavity or pharyngeal area treated in our institute from June 1995 to July 1998. Four cases had triple primary cancers. All 68 cases underwent upper and lower gastrointestinal endoscopy as well as ultrasonography of the liver. Lung CT was performed in cases with abnormal findings on chest roentgenograms. Multiple cancers were found in 5 of 25 oral cavity cases (20%), 6 of 14 mesopharynx cases (43%) and 12 of 29 hypopharynx cases (41%). Nine of 23 cases (39%) were synchronous and 14 (61%) were metachronous. Eighteen of 27 (69%) secondary cancers occurred in the upper aerodigestive tract with an especially high incidence (22%) in the esophagus. Gastroendoscopy also revealed 7 neoplastic lesions, aside from cancers, with the total abnormal rate of 24% (24/68). Thus, gastroendoscopy is useful for the diagnosis of multiple primary cancers. The frequency of multiple primary cancers in males (33%) was not different from that in females (35%). The average age of multiple primary cancer patients (65.1 years) was a little higher than that of single cancer patient (62.7 years). Smoking or drinking was not related to the incidence of multiple cancers. The interval between the first and the second cancer in metachronous cancer cases was 25.5 months on average, and within 4 years in 71% (10/14) of the cases. This result suggests that close follow-up including endoscopy should be required for at least 4 years after treatment of oral or pharyngeal cancer. Radical treatment for each of the multiple cancer lesions was performed in 22 of 23 cases, and the mortality rate of multiple primary cancer cases was not significantly different from that of single cancer cases. Among 7 cases who died of disease, 5 cases died of distant metastasis, suggesting that control of distant metastasis is an important issue in the treatment of multiple primary cancers.

Adult↗
PubMed1999

[Usefulness of power Doppler sonography for the assessment of subpleural lesions].

We investigated the usefulness of color Doppler power mode imaging for the assessment of subpleural lesions in 48 patients (27 with pneumonia, 4 with pulmonary abscesses, 12 with primary lung cancer, and 5 with metastatic lung cancer). We classified the patterns obtained by color flow imaging of subpleural lesions into six groups: type 0, no color flow; type I, spotty color flow; type II, linear color flow; type III, branchy color flow; and type IV, tortuous color flow, with type IV-A, for partial tortuous flow and type IV-B, for general tortuous flow. The color Doppler power mode proved better than velocity mode in terms of ability to generate clear color flow patterns. Color flow patterns obtained in power mode on the patients with pneumonia differed significantly from the patterns obtained on the lung cancer patients. Although the color flow patterns observed in power mode differed significantly for the benign and malignant groups, no statistically significant differences were observed in velocity mode. These findings illustrated the usefulness of color Doppler power mode imaging as a means of diagnosing benign and malignant subpleural lesions.

Adolescent↗
PubMed1998

Induction of protection against tetanus toxin in mice by tetanus toxoid-liposome conjugate.

Tetanus toxoid (Ttd) was coupled to liposomes via glutaraldehyde. Intraperitoneal injection in BALB/c mice with Ttd-liposomes induced a substantial amount of anti-Ttd IgG antibody production and an extremely low level of anti-Ttd IgE antibody production. Mice immunized with Ttd-liposomes were successfully protected against a subsequent challenge with a lethal dose of tetanus toxin (Ttx). On the other hand, aluminum hydroxide-adsorbed Ttd (Ttd-alum) and plain Ttd solution induced the production of both IgG and IgE antibodies against Ttd. Moreover, secondary immunization with Ttd-liposomes in mice, in which anti-Ttd IgE antibody production was induced by Ttd-alum led to enhanced anti-Ttd IgG and a limited anti-Ttd IgE antibody production. When Ttd-liposome preparation was lyophilized, the efficacy of Ttd-liposomes was maintained for 6 months at 37 C, suggesting that this vaccine preparation would be stable without refrigeration. These results demonstrate the potential ability of Ttd-liposome conjugates to produce a tetanus vaccine which provides protection against (Ttx) while inducing the least amount of anti-Ttd IgE antibodies.

Animals↗
PubMed1998

Induction of protection against oral infection with cytotoxin-producing Escherichia coli O157:H7 in mice by shiga-like toxin-liposome conjugate.

We have previously reported that purified Shiga-like toxins (SLT), SLT-I and SLT-II coupled with liposomes induced a substantial amount of anti-SLT-I and anti-SLT-II IgG antibody production, respectively, in mice. The levels of anti-SLT antibody in the sera of SLT-liposome-immune mice correlated well with the protection against subsequent challenge with SLT. In this study, mice were immunized intraperitoneally with the mixture of SLT-I-liposome and SLT-II-liposome and protection against oral infection with cytotoxin-producing Escherichia coli O157:H7 was evaluated. All of the mice that received immunization with the mixture of SLT-I-liposome and SLT-II-liposome were protected against subsequent intravenous challenge with 10 LD50 of either SLT-I or SLT-II. Eight weeks after primary immunization, mice were inoculated intragastrically with 10(9) CFU of E. coli O157:H7 strain 96-60. All SLT-liposome-immune mice tested survived without any apparent symptom while control mice died within 5 days. In addition, as shown by other antigen-liposome conjugates, SLT-liposome induced undetectable anti-SLT IgE antibody production while they induced substantial amounts of anti-SLT IgG antibodies. These results suggest that SLT-liposome conjugate may serve as a candidate vaccine that induces protection against cytotoxin-producing E. coli infection.

Animals↗
PubMed1997

Three acylated saponins and a related compound from Pithecellobium dulce.

Four new oleanane-type triterpene glycosides, pithedulosides H-K (1-4), were isolated from the seeds of Pithecellobium dulce. Their structures were established by extensive NMR experiments and chemical methods. Compounds 1-3 comprised acacic acid as the aglycon and either monoterpene carboxylic acid and its xyloside or monoterpene carboxylic acid as the acyl moiety at C-21. The oligosaccharide moieties linked to C-3 and C-28 were determined as alpha-L-arabinopyranosyl-(1-->2)-alpha-L-arabinopyranosyl-(1 -->6)- [beta-D-glucopyranosyl-(1-->2)]-beta-D-glucopyranosyl and alpha-L-arabinofuranosyl-(1-->4)-[beta-D-glucopyranosyl-(1-->3)]-alpha- rhamnopyranosyl-(1-->2)-beta-D-glucopyranosyl ester, respectively. Compound 4 was established as an echinocystic acid 3-O-glycoside having the same sugar sequences as 1-3. Also obtained in this investigation was the known compound 5, which was identified as echinocystic acid 3-O-beta-D-xylopyranosyl- (1-->2)-alpha-L-arabinopyranosyl-(1-->6)-[beta-D-glucopyranosyl-(1 -->2)]- beta-D-glucopyranoside.

Carbohydrate Sequence↗
PubMed1997

Protection against verocytotoxin in mice induced by liposome-coupled verocytotoxin.

Purified verocytotoxins (VTs), VT1 and VT2, were coupled to liposomes via glutaraldehyde. During the coupling procedure, both VT1 and VT2 were detoxified. Intraperitoneal injection in BALB/c mice with either VT1-liposome or VT2-liposome induced a substantial amount of anti-VT1 or anti-VT2 IgG antibody production, respectively. Mice immunized with VT2-liposome were protected against intravenous challenge with a lethal dose of VT2 and the degree of protection correlated well with the amount of IgG induced against VT2. Although VT1-liposome failed to induce protection against VT1, the decrease of the body weight observed after the toxin challenge correlated inversely with the amount of anti-VT1 IgG induced, suggesting that VT1 neutralizing antibody was present in VT1-liposome-immune mice. In addition, VT-liposome conjugate induced no detectable anti-VT IgE antibody production. These results demonstrate the potential ability of VT-liposome conjugates for the production of VT vaccine which induces protection against VTs.

Animals↗
PubMed1997

[Dynamic behavior of guinea pig middle ear].

The dynamic behavior of the middle ear was studied in living guinea pigs by using a laser Doppler vibrometer coupled to a compound microscope. Placing glass microbeads 20 microns in diameter on four points of the tympanic membrane and six points of the ossicles, their velocity amplitudes were measured under a constant stimulus of 65 dB SPL. Velocity responses of the four points on the tympanic membrane differed over the frequency range from 0.1 kHz to 3 kHz. At low frequencies, the malleus and incus rotated around an axis running from the malleus head to the incus short process. At middle frequencies, the whole ossicle had a piston-like motion. At high frequencies, the malleus and incus rotated around a vertical axis running through the ossicles, while the stapes had a hinge-like movement.

Animals↗