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Biomedical subjects

Akira Yamada

Publications and source records attributed to Akira Yamada.

At least 19 recordsLinked to original sources
PubMed2006

Matrix metalloproteinase-2, matrix metalloproteinase-9, and tissue inhibitor of metalloproteinase-1 in the peripheral blood of patients with various glomerular diseases and their implication in pathogenetic lesions: study based on an enzyme-linked assay and immunohistochemical staining.

BACKGROUND: Various glomerular diseases progress to end-stage renal failure due to an accumulation of the mesangial matrix (MM) and a thickening of the glomerular basement membrane (GBM). Both the MM and GBM are consistently metabolized through the synthesis and destruction of the matrix. Such synthesis is influenced by transforming growth factor-beta (TGF-beta) and other factors, whereas the destruction is presumed to be mediated by both matrix metalloproteinases (MMPs) and inhibitors of matrix metalloproteinases (TIMPs). Based on such evidence, we tried to detect MMP-2, MMP-9, and TIMP-1 in the peripheral blood of patients with various glomerular diseases. METHODS: Serum was used to detect MMP-2 and TIMP-1, while plasma was used to detect MMP-9. These enzymes were detected using an enzyme-linked assay. RESULTS: The findings showed an increased level of MMP-2 in patients with a alteration of GBM, typically membranous nephropathy (MN), regardless of the differences in their etiological processes. In contrast, MMP-9 did not show a strong association with any specific glomerular abnormalities. However, it mainly tended to increase in patients with MM accumulation. In addition, the localization of MMP-2, MMP-9, and TGF-beta1 was studied using immunohistochemical staining. MMP-2 was demonstrated to exist in the glomerular capillary loop (GCL) as well as in the mesangial cells and the mesangial matrix. MMP-9 was found to exist in mesangial cells and the matrix, GCL, infiltrated neutrophils, and some tubular epithelial cells. Positive staining for TGF-beta1 in GCL was found to be associated with an increased level of MMP-2 in patients with MN, whereas in MM such positive staining was not necessarily associated with an increased level of MMP-9. CONCLUSIONS: These results therefore suggest that MMP-2 plays an important role in the degradation of GBM, while MMP-9 only moderately affects the degradation of MM.

Enzyme-Linked Immunosorbent Assay↗
PubMed2006

High expression of APOBEC3G in patients infected with hepatitis C virus.

APOBEC3G (an apolipoprotein B mRNA-editing enzyme, catalytic polypeptide-like 3G; also known as CEM15), a member of the APOBEC family, which possesses cytidine deaminase activity that causes C/G to T/A transition mutations in virus genomes such as human immunodeficiency virus 1 and hepatitis B virus, is reported to play an important role in host-defense mechanisms. However, APOBEC3G expression in patients infected with chronic hepatitis C virus (HCV), of which there are currently more than 170 million worldwide, has not yet been well studied. We investigated this issue herein, and demonstrated an increased expression of APOBEC3G in both hepatocytes and lymphocytes of chronic hepatitis patients infected with HCV. Transfection of the NS5A gene, but not any other non-structural protein genes of HCV tested, to the hepatocellular carcinoma cell line enhanced APOBEC3G expression. Incubation of the cells with interferon also resulted in the augmentation. These results may provide new insight into the pathogenesis of chronic HCV infection.

APOBEC-3G Deaminase↗
PubMed2006

Striated muscle twitchin of bivalves has "catchability", the ability to bind thick filaments tightly to thin filaments, representing the catch state.

Catch muscles are found in some invertebrates which can maintain high passive tension with little energy expenditure for long periods after their active contraction. Twitchin in the catch muscles has the ability to facilitate the tight binding of thick filaments to thin filaments, which is the structural basis of the catch tension. We defined this ability as catchability and assessed the catchability of twitchins purified from striated muscles of an oyster (Crassostrea gigas) and a scallop (Mimachlamys nobilis), by using an in vitro catch assay where the binding of filaments could be directly visualized under a light microscope. We found that both twitchins had catchability, even though these muscles are not considered to be catch muscles in physiological experiments. In addition, these muscles contained water-soluble factors regulating the binding of the catch, probably protein kinase A and protein phosphatase 2B. These findings suggest that not only bivalve smooth muscles but also striated muscles have a system that regulates their relaxation rate through the catchability of twitchin, at least at the molecular level.

Animals↗
PubMed2006

Identification of hepatitis C virus (HCV) 2a-derived epitope peptides having the capacity to induce cytotoxic T lymphocytes in human leukocyte antigen-A24+ and HCV2a-infected patients.

Since virus-specific cytotoxic T lymphocytes (CTLs) play a critical role in preventing the spread of hepatitis C virus (HCV), vaccine-based HCV-specific CTL induction could be a promising strategy to treat HCV-infected patients. In this study, we tried to identify HCV2a-derived epitopes, which can induce human leukocyte antigen (HLA)-A24-restricted and peptide-specific CTLs. Peripheral blood mononuclear cells of HCV2a-infected patients or healthy donors were stimulated in vitro with HCV2a-derived peptides, which were prepared based on the HLA-A24 binding motif. As a result, three peptides (HCV2a 576-584, HCV2a 627-635, and HCV2a 1085-1094) efficiently induced peptide-specific CTLs from HLA-A24(+) HCV2a-infected patients as well as healthy donors. The cytotoxicity was exhibited by peptide-specific CD8(+) T cells in an HLA-A24-restricted manner. In addition, the HCV2a 627-635 peptide was frequently recognized by immunoglobulin G of HCV2a-infected patients. These results indicate that the identified three HCV2a peptides might be applicable to peptide-based immunotherapy for HLA-A24(+) HCV2a-infected patients.

Cell Line, Tumor↗
PubMed2006

Attenuation of cardiac dysfunction by a PPAR-alpha agonist is associated with down-regulation of redox-regulated transcription factors.

Peroxisome proliferator-activated receptor-alpha (PPAR-alpha) is a key regulator of lipid and glucose metabolism and is implicated in inflammation. We investigated the effects of the PPAR-alpha activator fenofibrate on, as well as the role of redox-regulated transcription factors, in the development of left ventricular (LV) hypertrophy and heart failure in Dahl salt-sensitive (DS) rats. DS rats were fed a high-salt diet and treated with either fenofibrate (30 or 50 mg/kg per day) or vehicle from 7 weeks of age. Fenofibrate inhibited the development of compensated hypertensive LV hypertrophy, attenuated the LV relaxation abnormality and systolic dysfunction, and improved the survival rate in DS rats. It also prevented a decrease in the ratio of reduced to oxidized glutathione and inhibited up-regulation of the DNA binding activities of the redox-regulated transcription factors NF-kappaB, AP-1, Egr-1, SP1, and Ets-1 induced in the left ventricle by the high-salt diet. Expression of target genes for these transcription factors, including those for adhesion molecules (VCAM-1, ICAM-1), cytokines (MCP-1), growth factors (TGF-beta, PDGF-B), and osteopontin, was also increased by the high-salt diet in a manner sensitive to treatment with fenofibrate. Furthermore, the infiltration of macrophages and T lymphocytes into the left ventricle and the increase in the plasma concentration of C-reactive protein were inhibited by fenofibrate. The PPAR-alpha activator fenofibrate thus attenuated the progression of heart failure and improved the survival rate in this rat model. These effects were associated with inhibition of the inflammatory response and of activation of redox-regulated transcription factors in the left ventricle.

Animals↗
PubMed2006

Recombinant human thioredoxin suppresses lipopolysaccharide-induced bronchoalveolar neutrophil infiltration in rat.

Human thioredoxin (TRX) is a multifunctional redox-active protein. We previously reported that the intraperitoneal administration of recombinant human thioredoxin (rhTRX) attenuates inflammatory cytokine- or bleomycin-induced lung injury in mice. In this study, the effect of rhTRX injected intravenously after lipopolysaccharide (LPS) injection was analyzed in rats. Rats were injected with LPS followed by treatment with rhTRX. Although the bolus injection exerted no protective effect, continuous intravenous administration of rhTRX significantly suppressed percentage number of neutrophils in bronchoalveolar lavage fluid. Histological examination also showed that rhTRX decreased neutrophil infiltration in the lung tissues. Administered rhTRX was mainly excreted into the urine and the tissue accumulation of rhTRX in the lung was marginal. LPS-induced oxidative stress in the lung was slight in this model. These results demonstrated that continuous intravenous administration of rhTRX suppresses LPS-induced bronchoalveolar neutrophil infiltration by an anti-chemotactic effect. Administration of rhTRX did not promote the tumor growth nor affect chemosensitivity in the xenotransplantation model, suggesting the safety of rhTRX therapy for cancer patients.

Animals↗
PubMed2006

Prognostic value of pacing-induced mechanical alternans in patients with mild-to-moderate idiopathic dilated cardiomyopathy in sinus rhythm.

OBJECTIVES: The relation between the occurrence of pacing-induced mechanical alternans and prognosis in patients with mild-to-moderate idiopathic dilated cardiomyopathy (IDCM) in sinus rhythm was investigated prospectively. The myocardial expression of genes for Ca2+-handling proteins in such patients was also examined. BACKGROUND: Mechanical alternans occurs in some patients with severe heart failure, but the relation between the occurrence of mechanical alternans and prognosis in patients with IDCM has remained unknown. METHODS: Left ventricular (LV) pressure was measured during atrial pacing, and LV endomyocardial biopsy specimens were collected in 36 IDCM patients and 8 controls. Idiopathic dilated cardiomyopathy patients were divided into two groups consisting of 22 individuals who did not develop mechanical alternans at heart rates up to 140 beats/min (group A) and of 14 individuals who did (group B). The patients were followed up for a mean of 3.7 years. RESULTS: There was no significant difference in LV ejection fraction or the plasma concentration of brain natriuretic peptide between groups A and B. The myocardial abundance of ryanodine receptor 2 messenger ribonucleic acid (mRNA) was significantly lower in groups A and B than in controls, whereas that of sarcoplasmic reticulum Ca2+-ATPase mRNA was significantly lower in group B than in group A or controls. Stepwise multivariate analysis identified pacing-induced mechanical alternans as the strongest predictor of cardiac events. Event-free survival in group A was significantly greater than that in group B. CONCLUSIONS: The occurrence of pacing-induced mechanical alternans is a potentially useful indicator of poor prognosis in patients with mild-to-moderate IDCM in sinus rhythm.

Adult↗
PubMed2006

Antitumor effects of systemic and local immunization with a CTL-directed peptide in combination with a local injection of OK-432.

PURPOSE: The accumulation of T cells into the tumor site is crucial for the elicitation of in vivo antitumor effects after cancer vaccination. In this study, we investigated the antitumor effects and associated mechanisms of action that were induced by systemic and local immunization with a CTL-directed peptide in combination with a peritumoral injection of a streptococcal preparation, OK-432. EXPERIMENTAL DESIGN AND RESULTS: The human SART3(315-323) peptide, which has the potential to induce human leukocyte antigen-A24-restricted CTLs, not only has the same amino acid sequence as the mouse SART3, but also has the capacity for binding to H-2K(d) molecules. Therefore, the SART3(315-323) peptide could be used as a tumor antigen-derived peptide in H-2(d) mice. Systemic immunization with the SART3(315-323) peptide and the subsequent peritumoral injection of both the SART3(315-323) peptide and OK-432 effectively induced peptide-specific and colon26 carcinoma-reactive CTLs in BALB/c mice. The combination therapy suppressed the growth of s.c. established colon26 carcinoma. The accumulation of both CD8(+) and CD4(+) T cells into the tumor site was more apparent in mice treated with the combination therapy than in those treated with other protocols. In addition, the level of IgG reactive to the administered SART3(315-323) peptide increased in mice that were treated with the combination therapy. CONCLUSION: These results indicate that antitumor effects could be efficiently induced by a combination therapy that included systemic and local immunization with a CTL-directed peptide together with a local injection of OK-432.

Amino Acid Sequence↗
PubMed2006

Nonmutated self-antigen-derived cancer vaccine peptides elicit an IgE-independent but mast cell-dependent immediate-type skin reaction without systemic anaphylaxis.

We previously reported an unexpected phenomenon, i.e., several cancer vaccine peptides, including a cyclophilin B-derived peptide (CypB-84), elicited an immediate-type skin reaction in prevaccination skin tests. These peptides were prohibited in the subsequent vaccinations because of a possible induction of systemic anaphylaxis. In this study, we investigated mechanisms involved in the peptide-elicited inflammatory reactions in BALB/c mice whose MHC class I molecule (Kd) shared similar binding motifs with the human HLA-A24 molecule. Among 11 peptides tested, all of which had been scheduled for use in clinical trials with HLA-A24+ cancer patients, three peptides (CypB-84, ART1-170, and ART4-13) elicited immediate footpad reactions in BALB/c mice similar to the skin reactions in humans. The footpad reaction was also observed in C57BL/6, athymic nu/nu, and CB17-SCID mice, but not in mast cell-deficient WBB6F1w/wv mice, indicating the reaction was not mediated by specific immunity, but was mast cell-dependent. Furthermore, the reactions were not correlated to in vivo antitumor effects of the peptides. An anaphylaxis was not elicited when the peptides were systemically injected due to a very rapid clearance of the peptides from the plasma by in vivo degradation. These results suggest that certain peptides of cancer vaccine candidates exhibit an IgE-independent but mast cell-dependent inflammatory response with no elicitation of systemic anaphylaxis, and may provide new insights for further development of peptide-based vaccinations for cancer patients.

Anaphylaxis↗
PubMed2006

Tubulointerstitial immune complex nephritis in a patient with systemic lupus erythematosus: role of peritubular capillaritis with immune complex deposits in the pathogenesis of the tubulointerstitial nephritis.

Class IV-G (A/C) diffuse lupus nephritis and tubulointerstitial (TI) nephritis in a 31-year old woman was studied by light, immunofluorescence (IF), and electron microscopy (EM), to determine the pathogenesis of the TI lesions. The light microscopic findings showed peritubular capillaritis in the interstitium, with ruptures in the capillary structure, lysis of the surrounding tubular basement membrane (TBM), extravasated red blood cells (RBCs), the infiltration of neutrophils and mononuclear cells, and edema. The IF study revealed IgG, IgA, IgM, C1q, C3, and C4 depositions along the TBM, on the capillary walls, and in the interstitium proper. The EM study disclosed the deposition of immune complexes in the TBM, the capillary wall, and the interstitium proper. Based on these findings, the TI nephritis in this patient was considered to be due to peritubular capillaritis secondary to the immune complex depositions in the capillary wall of the interstitium.

Adult↗
PubMed2006

Determination of antifungal activities in serum samples from mice treated with different antifungal drugs allows detection of an active metabolite of itraconazole.

To establish an in vitro method of predicting in vivo efficacy of antifungal drugs against Candida albicans and Aspergillus fumigatus, the antifungal activities of fluconazole, itraconazole, and amphotericin B were determined in mouse serum. The minimum inhibitory concentration (MIC) of each drug was measured using mouse serum as a diluent. For C. albicans, the assay endpoint of azoles was defined as inhibition of mycelial extension (mMIC) and for A. fumigatus, as no growth (MIC). The MICs of amphotericin B for both pathogens were defined as the MIC at which no mycelial growth occurred. Serum MIC or mMIC determinations were then used to estimate the concentration of the drugs in serum of mice treated with antifungal drugs by multiplying the antifungal titer of the serum samples by the serum (m)MIC. The serum drug concentrations were also determined by HPLC. The serum concentrations estimated microbiologically showed good agreement with those determined by HPLC, except for itraconazole. Analysis of the serum samples from itraconazole-treated mice by a sensitive bioautography revealed the presence of additional spots, not seen in control samples of itraconazole. The bioautography assay demonstrated that the additional material detected in serum from mice treated with itraconazole was an active metabolite of itraconazole. The data showed that the apparent reduction in the itraconazole serum concentration as determined by HPLC was the result of the formation of an active metabolite, and that the use of a microbiological method to measure serum concentrations of drugs can provide a method for prediction of in vivo efficacy of antifungal drugs.

Animals↗
PubMed2006

New epitope peptides derived from hepatitis C virus (HCV) 2a which have the capacity to induce cytotoxic T lymphocytes in HLA-A2+ HCV-infected patients.

Because cytotoxic T lymphocytes (CTLs) play an important role in the specific immunotherapy of hepatitis C virus (HCV) infection, a series of CTL epitopes has been defined from HCV genotype 1a or 1b protein. Here, we attempted to identify HCV2a-derived epitopes that are capable of inducing HLA-A2-restricted and peptide-specific CTLs. Peripheral blood mononuclear cells (PBMCs) of HLA-A2+ HCV2ainfected patients or healthy donors were stimulated in vitro with each of the HCV2a-derived peptides, which were prepared based on the HLA-A2-binding motif, and their peptide-specific and HLA-A2-restricted cytotoxicities were examined. The HCV2a 432-441, HCV2a 716-724, and HCV2a 2251-2260 peptides were found to efficiently induce peptide-specific CTLs from the PBMCs of HLA-A2+ HCV2ainfected patients. Cytotoxicity was mainly mediated by CD8+ T cells in a HLA class I-restricted manner. These results indicate that the HCV2a 432-441, HCV2a 716-724, and HCV2a 2251-2260 peptides might be applicable for peptide-based immunotherapy of HLA-A2+ HCV2a-infected patients.

Amino Acid Sequence↗
PubMed2006

DMRT-1 expression during NEC8 human embryonic carcinoma cell differentiation.

To elucidate the relationship between dsx and mab-3 related transcription factor 1 (Dmrt-1) and differentiation, alteration in mRNA levels during differentiation of NEC8 human embryonic carcinoma cells was investigated. After stimulation with 50 nM phorbol 12-myristate 13-acetate (PMA), the cells differentiated into cells with mesenchymal characteristics and upregulated Dmrt-1 mRNA, possibly through the protein kinase C/mitogen-activated protein kinase/activated protein-1 signaling pathway. Conversely, knockdown of Dmrt-1 by small interfering RNA resulted in cell morphology that was different from that after PMA treatment. These results indicated that Dmrt-1 expression was apparently associated with the differentiation of NEC8, and this cell line may be a helpful in vitro tool to clarify the role of Dmrt-1 in the differentiation process.

Adaptor Proteins, Signal Transducing↗
PubMed2006

Personalized peptide vaccines: a new therapeutic modality for cancer.

Therapeutic cancer vaccines have enjoyed little success so far, although many clinical trials have been conducted. Therefore, the creation of new protocols capable of inducing an objective response is required. We examined two of these protocols in the present review. The first is a personalized protocol to take into account the immunological diversity of cytotoxic T lymphocyte responses among patients. The second is a combination therapy designed to adapt to the presence of major histocompatibility complex (MHC)-loss cancer cells. The objective response rates of our classical (non-personalized) peptide vaccines were 0%, whereas that of personalized vaccines was 11.1% in the total advanced cancers and > or = 20% in malignant glioma and cervical cancers, respectively. A > or = 50% decrease in serum prostate-specific antigen (PSA) was seen in 8.7% of advanced hormone refractory prostate cancer patients by personalized vaccination alone, whereas such a decrease was seen in 54% of patients when the personalized vaccination was combined with a low dose of estramustine. Based on these experiences, we propose a personalized peptide vaccine combined with chemotherapy as a new treatment modality for cancers.

Cancer Vaccines↗
PubMed2006

Tensilin-like stiffening protein from Holothuria leucospilota does not induce the stiffest state of catch connective tissue.

The dermis of sea cucumbers is a catch connective tissue or mutable connective tissue that exhibits large changes in mechanical properties. A stiffening protein, tensilin, has been isolated from the sea cucumber Cucumaria frondosa. We purified a similar protein, H-tensilin, from Holothuria leucospilota, which belongs to a different family to C. frondosa. H-tensilin appeared as a single band with an apparent molecular mass of 34 kDa on SDS-PAGE. No sugar chain was detected. Tryptic fragments of the protein had homology to known tensilin. H-tensilin aggregated isolated collagen fibrils in vitro in a buffer containing 0.5 mol l(-1) NaCl with or without 10 mmol l(-1) Ca(2+). The activity of H-tensilin was quantitatively studied by dynamic mechanical tests on the isolated dermis. H-tensilin increased stiffness of the dermis in the soft state, induced by Ca(2+)-free artificial seawater, to a level comparable to that of the standard state, which was the state found in the dermis rested in artificial seawater with normal ionic condition. H-tensilin decreased the energy dissipation ratio of the soft dermis to a level comparable to that of the standard state. When H-tensilin was applied on the dermis in the standard state, it did not alter stiffness nor dissipation ratio. The subsequent application of artificial seawater in which the potassium concentration was raised to 100 mmol l(-1) increased stiffness by one order of magnitude. These findings suggest that H-tensilin is involved in the changes from the soft state to the standard state and that some stiffening factors other than tensilin are necessary for the changes from the standard to the stiff state.

Amino Acid Sequence↗
PubMed2006

Prostate-specific antigen-reactive cytotoxic T lymphocyte precursors in colon cancer patients.

Prostate-specific antigen (PSA) is a representative of the prostate-related antigens, and has been considered to be a tumor marker of prostate cancer. However, some studies suggest that PSA could be produced by several types of tumors. In the present study, we attempted to determine whether or not PSA could be a target molecule in specific immunotherapy for patients with colon cancer. Five colon cancer cell lines were examined for their PSA expression at the mRNA and protein levels by RT-PCR and immunocytostaining, respectively. As a result, four cell lines were found to be positive for PSA at both the mRNA and protein levels. We also attempted to determine whether PSA-reactive cytotoxic T lymphocytes (CTLs) could be induced from the peripheral blood mononuclear cells (PBMCs) of HLA-A24+ colon cancer patients by in vitro stimulation with PSA-derived peptides. As a consequence, PSA peptide-specific CTLs could be generated from the PBMCs of male and female colon cancer patients. Their cytotoxicity against HLA-A24+ PSA-expressing colon cancer cells was dependent on HLA class I-restricted and CD8+ T cells. These findings indicate that PSA-reactive CTL precursors are present in the periphery of colon cancer patients, and that PSA could be a target molecule in specific immunotherapy to colon cancer.

Cell Line, Tumor↗