PubMed Health⌕ Search

Biomedical subjects

Ichiro Nakamura

Publications and source records attributed to Ichiro Nakamura.

At least 19 recordsLinked to original sources
PubMed2006

Development of serological assays for Thottapalayam virus, an insectivore-borne Hantavirus.

Thottapalayam virus (TPMV), a member of the genus Hantavirus in the family Bunyaviridae, was isolated from an insectivore, Suncus murinus (musk shrew), captured in southern India in 1964. While the isolation of TPMV predates the discovery of the prototype Hantaan virus, little is known about its genetics and biology. To date, preliminary evidence suggests that TPMV differs significantly, both antigenically and genetically, from all known rodent-borne hantaviruses. However, since detailed epizootiological studies have not been conducted, it is unclear if TPMV is naturally harbored by an insectivore host or if TPMV represents a "spillover" from its natural rodent reservoir host. Moreover, to what extent TPMV causes infection and/or disease in humans is not known. To address these issues, we first studied the antigenic profile of TPMV using monoclonal antibodies against Hantaan and Seoul viruses and polyclonal immune sera against Puumala virus and TPMV. Armed with this newfound information, we developed an enzyme-linked immunosorbent assay system for the diagnosis of TPMV infections in shrews and humans, using a recombinant TPMV N antigen manipulated to have an E5/G6 epitope to be captured by monoclonal antibody clone E5/G6. Using this assay, we found anti-TPMV antibodies in sera from a patient with high fever of unknown etiology in Thailand and from two shrews captured in Indonesia. Seropositivity was verified by the indirect immunofluorescence antibody test, Western blotting analysis, and focus reduction neutralization test. Collectively, our data indicate that TPMV is harbored by Suncus murinus as its host in nature and is capable of infecting humans.

Animals↗
PubMed2006

Involvement of IL-10 in exhaustion of myeloid dendritic cells and rescue by CD40 stimulation.

It has recently been shown that immature dendritic cells (DCs) stimulated by a danger signal undergo transient maturation followed by exhaustion. However, the exact mechanism for this has not been elucidated. In this study, we show that interleukin-10 (IL-10) secreted from transiently matured DCs stimulated by danger signals is responsible for this rapid DC exhaustion. Blocking of the autocrine IL-10 enabled transient mature DCs to maintain the mature phenotype for several days. However, these DCs remained phenotypically unstable because the addition of IL-10 altered the transient mature DCs to exhausted DCs. More importantly, stimulation of DCs by CD40 protected transient mature DCs from IL-10-dependent exhaustion, with the result that mature DCs remained stable in the presence of IL-10. Furthermore, in vivo administration of stable mature DCs pulsed with ovalbumin protein induced antigen-specific cytotoxic T lymphocytes (CTLs) effectively, whereas neither exhausted DCs nor transient mature DCs were able to prime a strong antigen-specific CTL response. These results indicate that DC-T cell engagement via CD40-CD154 is required for stable DC maturation leading to effective CTL induction. Otherwise, DCs stimulated solely by a danger signal are temporarily activated, but then rapidly lose their immune-activating capacity under the influence of autocrine IL-10.

Animals↗
PubMed2006

The antihypertensive activity of angiotensin-converting enzyme inhibitory peptide containing in bovine lactoferrin.

Angiotensin I-converting enzyme (ACE) inhibitory peptide was isolated from the bovine lactoferrin hydrolysate using peptic hydrolysis by 2-step of reverse-phase high-performance liquid chromatography. This peptide was identified as Leu-Arg-Pro-Val-Ala-Ala and it produced a concentration-dependent inhibition of ACE activity in vitro with an IC50 value of about 4.14 microM. Also, this inhibition was identified as noncompetitive from the Lineweaver-Burk plot. Moreover, the antihypertensive activity of Leu-Arg-Pro-Val-Ala-Ala was investigated by the intravenous injection into spontaneously hypertensive rats (SHRs). A dose-dependent reduction of systolic blood pressure by this peptide was observed at 60 min after injection and it maximally decreased the blood pressure at a rate of 1 nmol/ml/kg. The blood pressure lowering activity of this peptide was calculated as 210% of captopril (10 pmol/ml/kg) that was used as positive control. Otherwise, identification of this peptide in the blood of SHRs was carried out chromatographically. Reduction of blood pressure coincides with the peak peptide concentration in the serum. Thus, we conclude that this peptide inhibits ACE activity in vitro and lowers systolic blood pressure in spontaneously hypertensive rat.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2006

A pseudotype vesicular stomatitis virus containing Hantaan virus envelope glycoproteins G1 and G2 as an alternative to hantavirus vaccine in mice.

We examined whether a vesicular stomatitis virus (VSV) pseudotype bearing the hantavirus envelope glycoproteins (GPs) G1 and G2 (VSVdeltaG*HTN) could be used as a safe and effective alternative to native hantavirus. Mice were immunized with purified particles of VSVdeltaG*HTN. After the second immunization, all mice produced anti-GP antibody as detected in ELISA and a neutralization test. After the third immunization, the mice were challenged with Hantaan virus. Neither anti-NP antibody production nor Hantaan virus-specific CD8 T-cell reactions were detected in these mice. The present study demonstrated the potential of using a pseudotype VSV system as a tool for developing a hantavirus vaccine.

Animals↗
PubMed2006

Skin behavior during leg lengthening in patients with achondroplasia and hypochondroplasia: a short-term observation during leg lengthening.

BACKGROUND: Although distraction osteogenesis is a recently established method of limb lengthening, it is not well known how soft tissues behave during bone lengthening. Because skin is tissue that can be easily and directly observed, we analyzed skin extension during limb lengthening to study the condition of soft tissues. METHOD: We examined three achondroplastic and two hypochondroplastic patients who underwent bilateral tibial lengthening with unilateral bone lengtheners. To analyze skin extension during leg lengthening, the bilateral skin surface was marked in a latticework pattern, starting 10 cm proximal to the knee joint down to 10 cm distal to the ankle joint, with black ink. The longitudinal length and the area of lattices, and the circumferential length of legs were measured. RESULTS: We found that: (1) the longitudinal extension of the skin during leg lengthening occurs not only in the bone lengthening portion between fixator pins but also around the knee or ankle joints; (2) circumferential length of legs was decreased, and soft tissue volume also does not increase in proportion to the increase in leg length. Soft tissue volume started to increase in the central region of the legs after a 30% increase in leg length was obtained, resulting in the 10% increase in the volume at the end point. CONCLUSIONS: These data suggest that soft tissue extension precedes soft tissue neogenesis at least during the initial period of leg lengthening, possibly based on its viscoelastic properties. After a 30% increase in leg length is obtained, soft tissue neogenesis takes place in the central region of the leg.

Achondroplasia↗
PubMed2006

New-onset demyelination induced by infliximab therapy in two rheumatoid arthritis patients.

Therapies aimed at inhibiting tumor necrosis factor, a proinflammatory cytokine implicated in autoimmune disease, are effective for rheumatoid arthritis (RA) and Crohn's disease. We report two patients who newly developed multiple demyelinating lesions in the central nervous system in the course of infliximab therapy for active RA. Neurological symptoms and the number of gadolinium-diethylenetriamine pentaacetic acid-enhanced lesions in magnetic resonance imaging gradually diminished with steroid treatment.

Aged↗
PubMed2006

Modeling and cost-effectiveness analysis of etanercept in adults with rheumatoid arthritis in Japan: a preliminary analysis.

The tumor necrosis factor (TNF) antagonist etanercept is an antirheumatic agent which was approved by Japanese regulatory authorities in January 2005. In Japan, the cost-effectiveness of this therapy for patients with rheumatoid arthritis (RA) has not previously been evaluated. This study models the cost-utility of etanercept in comparison with standard therapy with disease-modifying antirheumatic drugs (DMARDs) among adult Japanese RA patients who have failed a previous course of the DMARD bucillamine. A Markov model with 6-month cycles was constructed to compare two therapeutic strategies: etanercept versus standard therapy. For each cycle, one of three options was possible: a patient could (i) remain on current therapy if American College of Rheumatology criteria for 20% clinical improvement (ACR20) were achieved, (ii) switch to another drug in the therapeutic pathway if ACR20 was not achieved or if side effects severe enough to cause treatment discontinuation occurred, or (iii) they could die. The therapeutic pathway for the etanercept strategy was etanercept, methotrexate (MTX), sulfasalazine (SSZ), combination therapy (MTX + SSZ) and, finally, no DMARD. The pathway for standard therapy was identical except the initial therapy was MTX (etanercept was excluded). Results from clinical trials in U.S. and European patient populations were used to derive model probabilities for disease progression, response to drug therapy, and relationships between ACR20 response and functional improvement as measured by the Health Assessment Questionnaire (HAQ) disability index. An equation was developed to predict utility from HAQ scores of Japanese patients. Costs for drugs and medical services in Japan were obtained for April 2003. Analysis was conducted from a societal perspective, including lost productivity costs due to RA disability and premature mortality. Costs were discounted at 6% annually, and quality-adjusted life years (QALYs) at 1.5% annually. Model parameters were varied by 20% above and below base-case values in sensitivity analyses. Compared to standard therapy, the etanercept strategy was yen6.39 million more costly per patient but yielded an additional 2.56 QALYs. The incremental cost-utility ratio was yen 2.50 million/QALY. Sensitivity analyses revealed that cost-utility was most strongly influenced by the acquisition cost of etanercept and the percentage of etanercept recipients who achieved ACR20. Using commonly applied thresholds for acceptable cost-effectiveness in the United States ($50 000 = yen 5.5 million/QALY) and the United Kingdom (pound 30 000 = yen 5.7 million/QALY), etanercept therapy in Japan can be considered cost-effective. Cost-utility ratios did not exceed these thresholds in any sensitivity analysis. Further analyses should be conducted once clinical and epidemiologic data for Japanese patients become available.

Antirheumatic Agents↗
PubMed2006

Regulation of osteoclast differentiation and function by interleukin-1.

Interleukin-1 (IL-1) is a multifunctional cytokine that regulates various cellular and tissue functions. Among tissues, bone is the most sensitive to IL-1. IL-1 is a potent cytokine for bone resorption and participates in the multiple steps of osteoclast recruitment, such as differentiation, multinucleation, activation, and survival. On the other hand, considerable evidence has been accumulated over the past 10 years to indicate that this cytokine plays key roles in pathological bone destruction in a variety of human diseases, including rheumatoid arthritis, osteoporosis, and periodontal disease. In this chapter, we review the history of "IL-1 in bone" and the locus of this cytokine "from laboratory bench to bedside." A better understanding of the role of IL-1 in osteoclastic bone resorption would provide opportunities for developing new therapeutics to treat diseases of the bone.

Animals↗
PubMed2006

Molecular mechanism of the life and death of the osteoclast.

The life span of osteoclasts is critically regulated by various cytokines, and therapeutics such as bisphosphonates act directly on osteoclasts and induce apoptosis of the cells. This article will focus on the molecular mechanism of osteoclast apoptosis and summarize the recent advances in this field with an emphasis on the role of intracellular signaling pathways.

Animals↗
PubMed2006

Geographical distribution of hantaviruses in Thailand and potential human health significance of Thailand virus.

Phylogenetic investigations, sequence comparisons, and antigenic cross-reactivity studies confirmed the classification of Thailand virus (THAIV) as a distinct hantavirus species. The examination of sera from 402 rodents trapped in 19 provinces of Thailand revealed that five greater bandicoot rats (Bandicota indica) and one lesser bandicoot rat (B. savilei) from four provinces were focus reduction neutralization test (FRNT) antibody-positive for THAIV. One of 260 patients from Surin province in Thailand (initially suspected of having contracted leptospirosis, but found to be negative) showed symptoms compatible with hemorrhagic fever with renal syndrome (HFRS). The serum of this patient showed high titers of hantavirus-reactive IgM and IgG. FRNT investigations confirmed virus-neutralizing antibodies against THAIV. These observations suggest that THAIV or THAI-like viruses occur throughout Indochina and may represent an additional causative agent of HFRS.

Animals↗
PubMed2005

Repeated postoperative laryngeal obstruction due to bilateral cricoarytenoid joint involvement in rheumatoid arthritis.

A 61-year-old woman with a 40-year history of severe rheumatoid arthritis developed postoperative laryngeal obstruction twice; the first episode occurred just after surgery for cervical myelopathy and the second episode occurred 3 weeks after surgery when physiotherapy activity increased. A flexible laryngeal endoscopy demonstrated that abduction of the bilateral vocal cords was severely disturbed at the paramedian position, suggesting a diagnosis of cricoarytenoid arthritis. Early administration of corticosteroids was successful.

Journal Article↗
PubMed2005

Validation of low-temperature steam with formaldehyde sterilization for endoscopes, using validation device.

BACKGROUND: Validation of sterilization is an important step before clinical use of medical equipment. Adequate validation of sterilization of the endoscope has not been reported. One reason for this is the lack of suitable devices for validation. METHODS: The VDES (validation device for endoscope sterilization; Olympus prototype model, Olympus, Tokyo, Japan) was designed in two types (type A and type B) and resembles gastroscopes and duodenoscopes, respectively. Each type consists of inner and outer tubing and a central capsule containing a biological indicator. The device was designed to examine the effectiveness of low-temperature sterilizers, such as ethylene oxide gas, hydrogen peroxide gas plasma, and low-temperature steam with formaldehyde (LTSF) sterilizer. The aim of this study was to validate the sterilization of GI endoscopes by the LTSF sterilizer. Sterilization was assessed using both types of VDES after a 60-min application of LTSF. RESULTS: Culture of the biological indicator confirmed the complete eradication of the bacteria in a total of 10 experiments with each type of VDES after LTSF sterilization. CONCLUSIONS: Our results confirm that the LTSF sterilizer may sterilize endoscopes currently distributed by Olympus. Commercialization of VDES will make it possible to evaluate the reliability of sterilization when it is set in the sterilization device with endoscopes.

Bacillaceae↗
PubMed2005

[The treatment of rheumatoid arthritis with NF-kappaB inhibitors].

The nuclear factor kappaB (NF-kappaB) participates in the expression of a wide variety of genes that are involved in the regulation of host immune and inflammatory responses. In rheumatoid arthritis, the activation of NF-kappaB has been detected in synovium and lymphocytes, and induction of arthritis in mice produced strong NF-kappaB transcriptional activity in the affected joints. These evidences suggest that NF-kappaB is an interesting therapeutic target in rheumatoid arthritis. In this review, we are going to review briefly the signaling pathway that leads to NF-kappaB activation and then discuss the possibility that the inhibition of NF-kappaB might provide novel treatment to inhibit bone destruction in rheumatoid arthritis.

Animals↗
PubMed2004

Selective inhibition of NF-kappa B blocks osteoclastogenesis and prevents inflammatory bone destruction in vivo.

Bone destruction is a pathological hallmark of several chronic inflammatory diseases, including rheumatoid arthritis and periodontitis. Inflammation-induced bone loss of this sort results from elevated numbers of bone-resorbing osteoclasts. Gene targeting studies have shown that the transcription factor nuclear factor-kappa B (NF-kappa B) has a crucial role in osteoclast differentiation, and blocking NF-kappa B is a potential strategy for preventing inflammatory bone resorption. We tested this approach using a cell-permeable peptide inhibitor of the I kappa B-kinase complex, a crucial component of signal transduction pathways to NF-kappa B. The peptide inhibited RANKL-stimulated NF-kappa B activation and osteoclastogenesis both in vitro and in vivo. In addition, this peptide significantly reduced the severity of collagen-induced arthritis in mice by reducing levels of tumor necrosis factor-alpha and interleukin-1 beta, abrogating joint swelling and reducing destruction of bone and cartilage. Therefore, selective inhibition of NF-kappa B activation offers an effective therapeutic approach for inhibiting chronic inflammatory diseases involving bone resorption.

Animals↗
PubMed2004

Phenotypic stability of mature dendritic cells tuned by TLR or CD40 to control the efficiency of cytotoxic T cell priming.

It is generally accepted that after stimulation immature DCs turn into mature DCs, which present exogenous antigens together with their MHC class I molecules and then activate the antigen-specific CTLs. Although both TLR and CD40 stimulation appeared to provide the same effects on DC maturation, CD40-dependent CTL activation is much more potent than CTL activation through LPS stimulation. Despite their different outcomes, the factors that lead mature DCs to different functions remain largely undefined. In this study, we defined the transient maturation and subsequent deactivation of DCs by TLR stimuli, including those by LPS and CpG-ODN. In contrast, CD40 stimulation induced stable mature DCs that elicited sufficient CTL proliferation. The deactivated DCs, which we defined as "expired DCs," were phenotypically similar to immature DCs, except for their phenotype stability, MHC class I expression level and IL-10 production. Moreover, the functions of expired DCs were comparable to those of immature DCs in terms of CTL induction and tolerogenicity. These results may provide an explanation for the role of CD40 stimulation in antigen-specific CTL induction.

Animals↗
PubMed2004

Susceptibilities against bovine lactoferrin with microorganisms isolated from mastitic milk.

Antibacterial effects of bovine lactoferrin were studied in vitro against microorganisms isolated from mastitic milk in Tokachi area, Hokkaido, Japan. Microorganisms isolated were Escherichia coli (11 isolates), Klebsiella pneumoniae (5 isolates), enterococci (8 isolates), Staphylococcus aureus (10 isolates), coagulase negative staphylococci (CNS, 13 isolates), streptococci (11 isolates), Prototheca zopfii (7 isolates) and yeast-like fungi (9 isolates). Lactoferrin has been known as a multifunctional protein and its antimicrobial effect is one of the most essential function of it. In order to compare their susceptibilities against lactoferrin, the minimal inhibitory concentration values were estimated by a microplate assay method using 96-well microplate, which involved measuring the optical density of the cultures. Prototheca zopfii was highly sensitive to bovine lactoferrin and complete inhibition of this microorganism was observed even at the low concentration of 7 mug/ml. On the other hand, E. coli and enterococci showed resistance against lactoferrin action and staphylococci showed strain-dependent resistance.

Animals↗