Search PubMed⌕ Search

Biomedical subjects

Akio Yamada

Publications and source records attributed to Akio Yamada.

At least 37 records · Page 2Linked to original sources
PubMed2004

Two cases of adult Still's disease with abnormally high level of telomerase activity in peripheral blood mononuclear cells.

We report two patients with adult Still's disease with an abnormally high level of telomerase activity. The first patient was a 61-year-old woman. The mean telomerase activity value for peripheral blood mononuclear cells of healthy adults measured by our method was 0.13 +/- 0.03, whereas that in this patient during the active phase was abnormally high, at more than 27.56. The patient was treated by steroid therapy and successfully brought into remission, during which the telomerase activity value for peripheral blood mononuclear cells was reduced to 2.22. The second patient was a 19-year-old man. Although he stayed in remission after steroid therapy, a reduction in the steroid dose resulted in recrudescence, at which time the telomerase activity value peripheral blood mononuclear cells was high, at 11.76. Elevated levels of telomerase activity have been reported in patients with various pathological conditions other than malignant tumors. However, our literature search failed to reveal a report on such a high level of telomerase activity in association with a benign disease.

Journal Article↗
PubMed2004

Requirement of the actin cytoskeleton for the association of nectins with other cell adhesion molecules at adherens and tight junctions in MDCK cells.

Nectins, Ca(2+)-independent immunoglobulin-like cell adhesion molecules (CAMs), first form cell-cell adhesion where cadherins are recruited, forming adherens junctions (AJs) in epithelial cells and fibroblasts. In addition, nectins recruit claudins, occludin, and junctional adhesion molecules (JAMs) to the apical side of AJs, forming tight junctions (TJs) in epithelial cells. Nectins are associated with these CAMs through peripheral membrane proteins (PMPs), many of which are actin filament-binding proteins. We examined here the roles of the actin cytoskeleton in the association of nectins with other CAMs in MDCK cells stably expressing exogenous nectin-1. The nectin-1-based cell-cell adhesion was formed and maintained irrespective of the presence and absence of the actin filament-disrupting agents, such as cytochalasin D and latrunculin A. In the presence of these agents, only afadin remained at the nectin-1-based cell-cell adhesion sites, whereas E-cadherin and other PMPs at AJs, alpha-catenin, beta-catenin, vinculin, alpha-actinin, ADIP, and LMO7, were not concentrated there. The CAMs at TJs, claudin-1, occludin and JAM-1, or the PMPs at TJs, ZO-1 and MAGI-1, were not concentrated there, either. These results indicate that the actin cytoskeleton is required for the association of the nectin-afadin unit with other CAMs and PMPs at AJs and TJs.

Actin Cytoskeleton↗
PubMed2004

Detection of CD3epsilon polymorphism in cynomolgus monkeys by a method based on RFLP.

We previously reported that peripheral lymphocytes from about 12% of cynomolgus monkeys lacked reactivity with anti-rhesus monkey CD3 monoclonal antibody (FN18). The nucleotide sequence analysis of the genes encoding CD3 component proteins revealed that a single amino acid substitutions found in the CD3epsilon chain determined the phenotype. In this study, we attempted to develop a method based on the restriction fragment length polymorphism (RFLP) and apply it for determination of the genotypes of individual monkeys. Comparison of the phenotype determined by fluorescence-activated cell sorter analysis with the genotype determined by RFLP analysis revealed that the FN18 -positive trait was dominant over the FN18-negative trait. It was also revealed that allele frequency was significantly different among macaques depending on the geographical region where their ancestors were derived from.

Animals↗
PubMed2004

[Zoonoses].

The numbers of microbial species that can infect human beings are shown to be 1415, of which 868 species (61%) are zoonotic. Since most of the emerging pathogens (75%) are originated from other animals, public health sectors should be vigilant against the emergence of new zoonotic diseases. Only 33% of zoonoses can spread from human to human after introduction into human population. Various factors such as human demography, ecological change, global transportation and climate change are responsible for the emergence of zoonoses. Even a slight change in the ecological niche where pathogenic organisms thrive would result in the increase of the incidence of the disease.

Animals↗
PubMed2004

Preparation of a positive control DNA for molecular diagnosis of Bacillus anthracis.

Bacillus anthracis is considered to be one of the most potent biological weapons because of its highly pathogenic nature and efficiency of transmission. Routinely, a presumptive diagnosis of anthrax is achieved if the bands with predicted sizes are detected after the PCR targeted to the pag and cap genes residing on pXO1 and pXO2 plasmids, respectively. A positive control DNA prepared from the standard strains of B. anthracis (PAI and PAII) is usually included in the PCR tests. The handling of living B. anthracis, however, requires physical containment. The inclusion of DNA from B. anthracis as a positive control in the PCR test also has a potential risk of cross contamination that may confuse the results. In order to circumvent such problems, we attempted to construct a recombinant plasmid harboring the fragments of the pag and cap genes that could be distinguished from authentic sequences by the presence the restriction-enzyme site, the EcoRV site for the pag gene and the BamHI site for the cap gene, respectively, which were newly introduced. The strategy reported here provides a safe and reproducible positive-control DNA template. It also allows the detection of possible cross contamination, indicating that this strategy would be useful and convenient for the molecular identification of not only B. anthracis but also other highly pathogenic microbes.

Animals↗
PubMed2004

The absence of anti-rabies antibody in the sera of feral raccoons (Procyon lotor) captured in Hokkaido, Japan.

Feral raccoons captured in Hokkaido, Japan were examined for the presence of rabies virus neutralizing antibody (VNA). Between 2000 to 2002, 741 serum samples were collected and then subjected to VNA titer determination by rapid fluorescent focus inhibition test (RFFIT). Sera showing RFFIT titers of > or =1:25 have been considered as positive according to previous reports. VNA was detected in none of serum samples from the feral raccoons. The present study provides valuable background information for rabies prevention in Japan. The potential risk of raccoon-derived rabies in the wilderness has been of concern because of the increasing number of feral raccoons originally introduced from rabies-endemic countries. The continuous monitoring of sick and/or dead wild raccoons would help to prevent an epidemic spread of raccoon rabies.

Age Factors↗
PubMed2003

Immunogenicity of a Japanese encephalitis DNA vaccine candidate in cynomolgus monkeys.

A Japanese encephalitis (JE) vaccine candidate encoding JE virus premembrane (prM) and envelope (E) genes, designated pNJEME, was evaluated for safety and immunogenicity in non-human primate, cynomolgus monkeys. pNJEME was constructed using a vector (pNGVL4a) designed to address some of the safety concerns of DNA vaccine. In two different experiments, two immunizations with 300 microg of pNJEME by intramuscular (i.m.) injection, and 3 microg of pNJEME using a gene gun, and three immunizations by i.m. injection with 500 microg of pNJEME were performed. All the three protocols induced low to high levels of neutralizing antibody, indicating an ability of pNJEME to induce neutralizing antibody in monkeys with a wide individual variation in response to pNJEME. In one experiment designed to compare the DNA vaccine with a commercial inactivated JE vaccine, three immunizations by i.m. inoculation with 300 microg of pNJEME or by gene gun administration with 3 microg of pNJEME induced similar levels of neutralizing antibody to those induced by three immunizations with a human dose of the inactivated vaccine in most monkeys. After intranasal challenge with the Beijing P3 or JaTH160 strain of JE virus, pNJEME-immunized monkeys showed anamnestic neutralizing antibody responses, indicating that pNJEME induced memory B cells which were responsive to infection with JE virus. No systemic and local reactions were observed in any monkeys after i.m. or gene gun inoculations with plasmid DNAs.

Animals↗
PubMed2003

Involvement of nectin in the localization of IQGAP1 at the cell-cell adhesion sites through the actin cytoskeleton in Madin-Darby canine kidney cells.

IQGAP1, a putative downstream target of the Rho family small G proteins, Cdc42 and Rac, localizes at adherens junctions (AJs) in epithelial cells. It has been suggested that IQGAP1 localizes at AJs through its binding to beta-catenin, and negatively regulates the E-cadherin-mediated cell-cell adhesion. Nectin is a Ca(2+)-independent, immunoglobulin-like cell-cell adhesion molecule that localizes at AJs. Nectin is associated with E-cadherin through their respective cytoplasmic tail-binding proteins, afadin and catenins, and involved in the formation of AJs cooperatively with E-cadherin. Here we investigated a role of nectin in the localization of IQGAP1 at AJs. Ca(2+) chelation from the medium causes disruption of the E-cadherin-mediated cell-cell adhesion, but not the nectin-based cell-cell adhesion, in Madin-Darby canine kidney (MDCK) cells. IQGAP1 remained at the residual nectin-based cell-cell adhesion sites where the E-cadherin immunofluorescence signal disappeared. Restoration of Ca(2+) in the medium causes re-accumulation of E-cadherin to the residual nectin-based cell-cell adhesion sites to re-form AJs. Nectin inhibitors inhibit this re-accumulation of E-cadherin to re-form AJs by impairing the nectin-based cell-cell adhesion. The nectin inhibitors also reduced the localization of IQGAP1 at the cell-cell adhesion sites. When MDCK cells were incubated with microbeads coated with the extracellular fragment of nectin that interacts with cellular nectin, IQGAP1 also accumulated at the bead-MDCK cell contact sites. The accumulation of IQGAP1 at the cell-cell adhesion sites was inhibited by actin filament-disrupting agents, latrunculin A and cytochalasin D. These results indicate that nectin is involved in the localization of IQGAP1 at AJs through the actin cytoskeleton.

Actins↗
PubMed2003

Nectin-dependent localization of synaptic scaffolding molecule (S-SCAM) at the puncta adherentia junctions formed between the mossy fibre terminals and the dendrites of pyramidal cells in the CA3 area of the mouse hippocampus.

BACKGROUND: Two types of intercellular junctions, synaptic junctions (SJs) and puncta adherentia junctions (PAs), are observed at the synapses between the mossy fibre terminals and the dendrites of pyramidal cells in the CA3 area of the hippocampus. SJs are associated with active zones and postsynaptic densities (PSDs) where neurotransmission occurs, whereas PAs are not associated with either of them. We have found that the nectin-afadin unit as well as the N-cadherin-catenin unit localizes at the PAs and that both the units cooperatively organize the PAs. Nectins are Ca2+-independent Ig-like cell-cell adhesion molecules and afadin is a nectin- and actin filament-binding protein that connects nectins to the actin cytoskeleton. Synaptic scaffolding molecule (S-SCAM) is a neural scaffolding protein which interacts with many proteins including neuroligin, NMDA receptors, neural plakophilin-related armadillo-repeat protein/delta-catenin, a GDP/GTP exchange protein for Rap1 small G protein (PDZ-Rap-GEP), and beta-catenin. S-SCAM has been suggested to be a component of PSDs, but its precise localization at the synapses remains unknown. RESULTS: S-SCAM was not concentrated at the PSDs but highly concentrated and co-localized with nectins at both the sides of the PAs formed between the mossy fibre terminals and the dendrites of pyramidal cells in the CA3 area of the adult mouse hippocampus. S-SCAM co-localized with nectin-1 at the primitive synapses where the SJs and the PAs were not morphologically differentiated, and they co-localized during the maturation of the SJs and the PAs. Nectin-1 had a potency to recruit S-SCAM to the nectin-1-based cell-cell adhesion sites formed in cadherin-deficient L cells as a model system. This recruitment was dependent on the C-terminal PDZ domain-binding motif of nectin-1 which is necessary for the binding of afadin, suggesting that nectins recruit S-SCAM through afadin. Consistently, S-SCAM was co-immunoprecipitated with afadin by the anti-S-SCAM antibody from the mouse brain, but S-SCAM did not directly bind afadin. CONCLUSION: These results indicate that S-SCAM localizes at the PAs in the CA3 area of the hippocampus in a nectin-dependent manner and suggest that S-SCAM serves as a scaffolding molecule at the PAs after maturation of the synapses and at the SJs during the maturation.

Adaptor Proteins, Signal Transducing↗
PubMed2003

Cross-reactive antigenicity of nucleoproteins of lyssaviruses recognized by a monospecific antirabies virus nucleoprotein antiserum on paraffin sections of formalin-fixed tissues.

Diagnosis of rabies is routinely confirmed by detection of rabies virus antigens in acetone-fixed frozen brain tissues or imprint smears using an immunofluorescence method with commercial antirabies virus antibodies. Since recent molecular analyses disclosed wide heterogeneity in the genome sequences of rabies virus strains and related lyssaviruses, it is necessary to confirm the presence of common epitopes in these lyssaviruses. In this study we confirmed the presence of cross-reactive antigens of various lyssaviruses in paraffin sections of formalin-fixed tissue using a monospecific rabbit antiserum prepared by immunization with a recombinant nucleoprotein of rabies virus. By immunohistochemical application, the antigen was detected predominantly in the cytoplasm of neurons in the brains of mice infected with rabies virus, Duvenhage virus, Mokola virus and European bat lyssavirus-1, while no cross-reaction was observed in uninfected humans and animals including dogs, bats, and raccoons. In addition, we examined one autopsy case that was infected in a rabies-endemic nation and developed the clinical manifestation of rabies after returning to Japan in 1970, and found that the antigen was well preserved in paraffin sections of formalin-fixed tissues. Thus, this suggests that the lyssavirus-specific antigen is recognized by the monospecific antibody against rabies virus nucleoprotein, and that this cross-reactive antigen is detectable on formalin-fixed paraffin-embedded tissues by immunohistochemical analysis.

Amino Acid Sequence↗
PubMed2003

Telomerase activity and telomere length of peripheral blood mononuclear cells in SLE patients.

We evaluated the clinical significance of the telomerase activity and telomere length of peripheral blood mononuclear cells (PBMC) in systemic lupus erythematosus (SLE). PBMC were isolated from 55 patients with SLE and the telomerase activity was measured by TRAP assay. The telomere length of PBMC was also measured in 30 of these subjects. As a control group, 45 healthy adults with no particular clinical history were studied. The results were compared with clinical data. In patients with active SLE, the telomerase activity of PBMC was significantly increased compared with the control group. In patients with inactive SLE, the PBMC telomerase activity was not different compared with the controls in their 20s, 30s and 40s, but it was significantly increased compared with the controls in their 50s. In SLE patients, the telomerase activity of PBMC was significantly correlated with modified SLEDAI. The telomere length of PBMC in younger SLE patients tended to be shorter than that in the controls, but no difference was observed in older patients. The correlation coefficient between the telomerase activity and telomere length of PBMC in SLE patients was not significant. Abnormalities in the telomerase activity and telomere length observed in SLE patients are considered to be important findings for evaluation of the pathology of SLE.

Adolescent↗
PubMed2003

Safe and easy monitoring of anti-rabies antibody in dogs using his-tagged recombinant N-protein.

The virus neutralization (VN) test is a reliable indicator of adequate vaccination in animals. However, the VN test is tedious and complicated to perform. Enzyme-linked immunosorbent assay (ELISA), though rapid and simple compared to the VN test, is complicated and hazardous during preparation of the viral antigen. In an effort to overcome the disadvantage of ELISA, the recombinant His-tagged nucleoprotein (His-rNP) expressed in Escherichia coli was used as a safe antigen for ELISA (i.e., live virus was not used). Anti-rabies antibody levels were determined by fluorescent ELISA (FELISA) using His-rNP as an antigen. The presence of anti-rabies VN antibody was determined by the rapid fluorescent focus inhibition test (RFFIT). The VN titers by RFFIT were found to correlate well with the FITC-signal determined by the FELISA (r = 0.616). The sensitivity and specificity of the FELISA were 91.7 and 100%, respectively. This study showed that the His-rNP could be useful as an antigen of ELISA to test for anti-rabies antibody in vaccinated dogs. Several studies in Japan have investigated the antibody level in the sera of vaccinated dogs. A safe and convenient test using His-rNP would contribute to our understanding of the status of herd immunity among not only domestic dogs but also stray dogs in Japan.

Animals↗
PubMed2002

ADIP, a novel Afadin- and alpha-actinin-binding protein localized at cell-cell adherens junctions.

Afadin is an actin filament (F-actin)-binding protein that is associated with the cytoplasmic tail of nectin, a Ca(2+)-independent immunoglobulin-like cell-cell adhesion molecule. Nectin and afadin strictly localize at cell-cell adherens junctions (AJs) undercoated with F-actin bundles and are involved in the formation of AJs in cooperation with E-cadherin in epithelial cells. In epithelial cells of afadin (-/-) mice and (-/-) embryoid bodies, the proper organization of AJs is markedly impaired. However, the molecular mechanism of how the nectin-afadin system is associated with the E-cadherin-catenin system or functions in the formation of AJs has not yet been fully understood. Here we identified a novel afadin-binding protein, named ADIP (afadin DIL domain-interacting protein). ADIP consists of 615 amino acids with a calculated M(r) of 70,954 and has three coiled-coil domains. Northern and Western blot analyses in mouse tissues indicated that ADIP was widely distributed. Immunofluorescence and immunoelectron microscopy revealed that ADIP strictly localized at cell-cell AJs undercoated with F-actin bundles in small intestine absorptive epithelial cells. This localization pattern was the same as those of afadin and nectin. ADIP was undetectable at cell-matrix AJs. ADIP furthermore bound alpha-actinin, an F-actin-bundling protein known to be indirectly associated with E-cadherin through its direct binding to alpha-catenin. These results indicate that ADIP is an afadin- and alpha-actinin-binding protein that localizes at cell-cell AJs and may have two functions. ADIP may connect the nectin-afadin and E-cadherin-catenin systems through alpha-actinin, and ADIP may be involved in organization of the actin cytoskeleton at AJs through afadin and alpha-actinin.

Actinin↗
PubMed2002

Involvement of nectin in the localization of junctional adhesion molecule at tight junctions.

Junctional adhesion molecule (JAM) is a Ca2+-independent immunoglobulin-like cell-cell adhesion molecule which localizes at tight junctions (TJs). Claudin is a key cell-cell adhesion molecule that forms TJ strands at TJs. JAM is associated with claudin through their cytoplasmic tail-binding protein, ZO-1. JAM is furthermore associated with Par-3, a cell polarity protein which forms a ternary complex with Par-6 and atypical protein kinase C. Nectin is another Ca2+-independent immunoglobulin-like cell-cell adhesion molecule which localizes at adherens junctions (AJs). Nectin is associated with E-cadherin through their respective cytoplasmic tail-binding proteins, afadin and catenins, and involved in the formation of AJs cooperatively with E-cadherin. We show here that nectin is furthermore involved in the localization of JAM at TJs. During the formation of the junctional complex consisting of AJs and TJs in Madin-Darby canine kidney (MDCK) cells, JAM was recruited to the nectin-based cell-cell adhesion sites. This recruitment of JAM was inhibited by nectin inhibitors, which inhibited the trans-interaction of nectin. Microbeads coated with the extracellular fragment of nectin, that interacted with cellular nectin, also recruited JAM to the bead-MDCK cell contact sites. Furthermore, when cadherin-deficient L fibroblasts stably expressing both exogenous JAM and nectin (nectin-JAM-L cells) were co-cultured with L fibroblasts expressing only nectin (nectin-L cells), JAM was concentrated at the cell-cell adhesion sites between nectin-JAM-L and nectin-L cells without the trans-interaction of JAM. Analyses of the localization and immunoprecipitation of JAM revealed that it was associated with nectin through afadin and ZO-1. These results suggest that nectin has a role in the localization of JAM at TJs in the process of the formation of the junctional complex in epithelial cells.

Animals↗
PubMed2002

Role of nectin in organization of tight junctions in epithelial cells.

BACKGROUND: In polarized epithelial cells, cell-cell adhesion forms specialized membrane structures comprised of claudin-based tight junctions (TJs) and of E-cadherin-based adherens junctions (AJs). These structures are aligned from the apical to the basal side of the lateral membrane, but the mechanism of this organization remains unknown. Nectin is a Ca2+ independent immunoglobulin-like cell-cell adhesion molecule which localizes at AJs. Nectin is associated with E-cadherin through their respective cytoplasmic tail-binding proteins, afadin and catenins, and involved in the formation of AJs in cooperation with E-cadherin. We show here that nectin is also involved in the formation of TJs. RESULTS: During the formation of the junctional complex consisting of AJs and TJs in Madin-Darby canine kidney (MDCK) cells, claudin and occludin accumulated at the apical sites of the nectin-based cell-cell adhesion sites. This accumulation of claudin and occludin was inhibited by inhibitors acting on the trans interaction of nectin. The barrier function of TJs was also impaired by the nectin inhibitors. It has been shown that a phorbol ester promotes the formation of a TJ-like structure in an E-cadherin-independent manner. This phorbol ester-induced formation of the TJ-like structure was also inhibited by the nectin inhibitors. CONCLUSIONS: These results suggest a role of the nectin-afadin system in the organization of TJs as well as AJs in epithelial cells.

Animals↗
PubMed2002

[Predictive factors of prognosis in rheumatoid arthritis].

Rheumatoid arthritis leads the patients to severe physical disability and the mortality is significantly worse than general population. To predict the prognosis at first visit in hospital is difficult but there are several factors influence on the prognosis; disease activity and it's duration, high titer of rheumatoid factor, male and vasculitis. The most important factor is disease activity and it's duration. Recent advance of the treatment of RA improve the prognosis of either disability or mortality. Adverse effects of drugs for RA may threaten the life but their use leads statistically significant improvement of mortality.

Arthritis, Rheumatoid↗