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Biomedical subjects

M Nagai

Publications and source records attributed to M Nagai.

At least 37 records · Page 2Linked to original sources
PubMed2001

CD8(+) T cells are an in vivo reservoir for human T-cell lymphotropic virus type I.

It is thought that human T-cell lymphotropic virus type I (HTLV-I) preferentially infects CD4(+) T cells in vivo. However, observations of high HTLV-I proviral load in patients with HTLV-I-associated myelopathy/tropical spastic paraparesis suggest that HTLV-I may infect other cell types in addition to CD4(+) T cells. To identify in vivo T-cell tropisms of HTLV-I, real-time quantitative polymerase chain reaction (PCR) and intracellular protein staining were used. A high amount of HTLV-I proviral DNA was detected from purified CD8(+) T cells by quantitative PCR (between 1.64 and 62.83 copies of HTLV-I provirus per 100 isolated CD8(+) T cells). CD8(+) T cells expressed HTLV-I-related antigens (HTLV-I Tax and p19 protein) after a short time in cultivation. These results demonstrate that CD8(+) T cells are also infected with HTLV-I and express HTLV-I antigens at levels that are comparable to HTLV-I-infected CD4(+) cells. Therefore, CD8(+) cells are an additional viral reservoir in vivo for HTLV-I and may contribute to the pathogenesis of HTLV-I-mediated disorders.

CD4-Positive T-Lymphocytes↗
PubMed2001

In vitro spontaneous lymphoproliferation in patients with human T-cell lymphotropic virus type I-associated neurologic disease: predominant expansion of CD8+ T cells.

Peripheral blood mononuclear cells (PBMCs) from patients with human T-cell lymphotropic virus type I (HTLV-I)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) proliferate spontaneously in vitro. This spontaneous lymphoproliferation (SP) is one of the immunologic hallmarks of HAM/TSP and is considered to be an important factor related to the pathogenesis of HAM/TSP. However, the cell populations involved in this phenomenon have not yet been definitively identified. To address this issue, the study directly evaluated proliferating cell subsets in SP with a flow cytometric method using bromodeoxyuridine and Ki-67. Although both CD4+ and CD8+ T cells proliferated spontaneously, the percentage of proliferating CD8+ T cells was 2 to 5 times higher than that of CD4+ T cells. In addition, more than 40% of HTLV-I Tax11-19-specific CD8+ T cells as detected by an HLA-A*0201/Tax11-19 tetramer proliferated in culture. In spite of this expansion of HTLV-I-specific CD8+ T cells, HTLV-I proviral load did not decrease. This finding will help elucidate the dynamics of in vivo virus-host immunologic interactions that permit the coexistence of high HTLV-I-specific CD8+ cytotoxic T-lymphocyte responses and high HTLV-I proviral load in HAM/TSP.

Adult↗
PubMed2001

Electron-hole droplet formation in direct-gap semiconductors observed by mid-infrared pump-probe spectroscopy.

Mid-infrared pump-probe measurements with subpicosecond time resolution reveal the existence of a metastable condensed phase of the electron-hole ensemble in a direct-gap semiconductor CuCl. High-density electrons and holes are directly created in a low-temperature state by the resonant femtosecond excitation of excitons above the Mott transition density. Strong metallic reflection with a plasma frequency Planck's over 2pi(omega)p approximately 0.5 eV builds up within 0.3 ps. Within a few picoseconds, the mid-infrared reflection spectrum is transformed from metalliclike into colloidlike. The observed resonance feature at Planck's over 2pi(omega)p/sqrt[3] allows us to obtain the carrier density in the metastable electron-hole droplets of 2x10(20) cm(-3).

Journal Article↗
PubMed2001

Anxiety affects the postural sway of the antero-posterior axis in college students.

To examine whether the postural balance is influenced by the degree of anxiety, body sway during orthostatic standing while gazing at a visual target was examined in college students. Students, physically and mentally healthy, were divided into two groups according to the degree of state anxiety; high anxiety group (HA) and low anxiety group (LA). A fast Fourier transform analysis of the postural sway in antero-posterior axis showed that frequency components of 0.02-0.21 Hz, reflecting vestibular inputs, were 16% greater and those of 2.02-10.0 Hz, reflecting somatosensory inputs, were 24% smaller in HA. These differences between HA and LA were abolished when the eyes were closed. It is concluded that the interactions of visual inputs with vestibular and somatosensory inputs are influenced by anxiety.

Adolescent↗
PubMed2001

Analysis of transforming activity of human synovial sarcoma-associated chimeric protein SYT-SSX1 bound to chromatin remodeling factor hBRM/hSNF2 alpha.

Human synovial sarcoma has been shown to exclusively harbor the chromosomal translocation t(X;18) that produces the chimeric gene SYT-SSX. However, the role of SYT-SSX in cellular transformation remains unclear. In this study, we have established 3Y1 rat fibroblast cell lines that constitutively express SYT, SSX1, and SYT-SSX1 and found that SYT-SSX1 promoted growth rate in culture, anchorage-independent growth in soft agar, and tumor formation in nude mice. Deletion of the N-terminal 181 amino acids of SYT-SSX1 caused loss of its transforming activity. Furthermore, association of SYT-SSX1 with the chromatin remodeling factor hBRM/hSNF2 alpha, which regulates transcription, was demonstrated in both SYT-SSX1-expressing 3Y1 cells and in the human synovial sarcoma cell line HS-SY-II. The binding region between the two molecules was shown to reside within the N-terminal 181 amino acids stretch (aa 1--181) of SYT-SSX1 and 50 amino acids (aa 156--205) of hBRM/hSNF2 alpha and we found that the overexpression of this binding region of hBRM/hSNF2 alpha significantly suppressed the anchorage-independent growth of SYT-SSX1-expressing 3Y1 cells. To analyze the transcriptional regulation by SYT-SSX1, we established conditional expression system of SYT-SSX1 and examined the gene expression profiles. The down-regulation of potential tumor suppressor DCC was observed among 1,176 genes analyzed by microarray analysis, and semi-quantitative reverse transcription--PCR confirmed this finding. These data clearly demonstrate transforming activity of human oncogene SYT-SSX1 and also involvement of chromatin remodeling factor hBRM/hSNF2 alpha in human cancer.

Agar↗
PubMed2001

Role of the conserved acidic residue Asp21 in the structure of phosphatidylinositol 3-kinase Src homology 3 domain: circular dichroism and nuclear magnetic resonance studies.

To elucidate a role of the Src homology 3 (SH3)-conserved acidic residue Asp21 of the phosphatidylinositol 3-kinase (PI3K) SH3 domain, structural changes induced by the D21N mutation (Asp21 --> Asn) were examined by circular dichroism (CD) and nuclear magnetic resonance (NMR) spectroscopies. In the previous study, we demonstrated that environmental alterations occurred at the side chains of Trp55 and some Tyr residues from the comparison of the near-UV CD spectra of the PI3K SH3 domain with or without a D21N mutation [Okishio, N., et al. (2000) Biopolymers 57, 208-217]. In this work, the affected Tyr residues were identified as Tyr14 and Tyr73 by the CD analysis of a series of mutants, in which every single Tyr residue was replaced by a Phe residue with or without a D21N mutation. The (1)H and (15)N resonance assignments of the PI3K SH3 domain and its D21N mutant revealed that significant chemical shift changes occurred to the aromatic side-chain protons of Trp55 and Tyr14 upon the D21N mutation. All these aromatic residues are implicated in ligand recognition. In addition, the NMR analysis showed that the backbone conformations of Lys15-Asp23, Gly54-Trp55, Asn57-Gly58, and Gly67-Pro70 were affected by the D21N mutation. Furthermore, the (15)N[(1)H] nuclear Overhauser effect values of Tyr14, Glu19, and Glu20 were remarkably changed by the mutation. These results show that the D21N mutation causes structural deformation of more than half of the ligand binding cleft of the domain and provide evidence that Asp21 plays an important role in forming a well-ordered ligand binding cleft in cooperation with the RT loop (Lys15-Glu20).

Amino Acid Substitution↗
PubMed2001

Increased HTLV-I proviral load and preferential expansion of HTLV-I Tax-specific CD8+ T cells in cerebrospinal fluid from patients with HAM/TSP.

To date, high human T-cell lymphotropic virus type I proviral load in patients with human T-cell lymphotropic virus type I-associated myelopathy/tropical spastic paraparesis has been reported and is thought to be related to the pathogenesis of human T-cell lymphotropic virus type I-associated myelopathy/tropical spastic paraparesis. However, the proviral load in cerebrospinal fluid has not been well investigated. We measured human T-cell lymphotropic virus type I proviral load in cerebrospinal fluid cells from human T-cell lymphotropic virus type I-associated myelopathy/tropical spastic paraparesis patients using real-time quantitative polymerase chain reaction (TaqMan). Human T-cell lymphotropic virus type I proviral load in cerebrospinal fluid cells were significantly higher than that of the matched peripheral blood mononuclear cells, and a high ratio of human T-cell lymphotropic virus type I proviral load in cerebrospinal fluid cells to peripheral blood mononuclear cells were observed in patients with short duration of illness. Human T-cell lymphotropic virus type I Tax-specific CD8+ T cells, as detected by peptide-loaded HLA tetramers, accumulated in cerebrospinal fluid compared with that in peripheral blood mononuclear cells, while the frequency of cytomegalovirus-specific CD8+ T cells in cerebrospinal fluid was reduced. These observations suggest that accumulation of both human T-cell lymphotropic virus type I-infected cells and preferential expansion of human T-cell lymphotropic virus type I-specific CD8+ cells in cerebrospinal fluid may play a role in the pathogenesis of human T-cell lymphotropic virus type I-associated myelopathy/tropical spastic paraparesis.

Adolescent↗
PubMed2001

Genomic and serological diversity of bovine viral diarrhea virus in Japan.

Genomic properties of 62 field isolates of bovine viral diarrhea virus (BVDV) collected from 1974 to 1999 in Japan were investigated. The 5' untranslated region (UTR) was amplified by reverse transcriptase-polymerase chain reaction (RT-PCR) and the 244 to 247 base nucleotide sequences were determined. Serological properties were also characterized by the cross-neutralization test using antisera against the representative strain of the classified genotype. Using phylogenetic tree analysis, BVDV 1 was subdivided into two major clusters, BVDV-1a (29 isolates) and BVDV-1b (27 isolates). In group 1a, 3 differed from the other viruses, and were classified in a branch assigned as 1a'. However, 4 isolates (So CP/75, 190 CP, 190 NCP and KS86-1-NCP) could not be assigned to group 1a or 1b. In comparison with the published sequence data, KS86-1-NCP, 190 CP and 190 NCP were similar to the Southern Africa isolates that have recently been proposed as BVDV 1c. The 5' UTR sequence of So CP/75 was unique among those of BVDV 1, suggesting that the isolate should be classified into a new genotype. Only 2 out of 62 isolates collected in 1989 and 1990 were identified as BVDV 2. The results of the cross-neutralization test strongly supported these data, suggesting a close correlation between the 5' UTR sequence and the antigenicity of BVDV.

5' Untranslated Regions↗
PubMed2001

Tetrahydroisoquinoline-monoterpene and iridoid glycosides from Alangium lamarckii.

From the water soluble fraction of the dried fruits of Alangium lamrckii, four tetrahydroisoquinoline-monoterpene glycosides, 6-O-methyl-N-deacetylisoipecosidic acid, 7-O-methyl-N-deacetylisoipecosidic acid, 6,7-di-O-methyl-N-deacetylisoipecosidic acid and 6"-O-alpha-D-glucopyranosyl-6-O-methyl-N-deacetylisoipecosidic acid, and an iridoid glycoside, 6'-O-alpha-D-glucopyranosylloganic acid, were isolated, together with six known compounds. The structures of the previously unknown compounds were determined by spectroscopic and chemical means. The significance of these glucosides in the biogenesis of Alangium alkaloids is discussed; 6-O-methyl-N-deacetylisoipecosidic acid was also chemically converted into 10-O-demethylprotoemetine and dihydroisoalangine.

Asteraceae↗
PubMed2001

Vaccination with MCP-1 cDNA transfectant on human malignant glioma in nude mice induces migration of monocytes and NK cells to the tumor.

Recently, studies on vaccination with tumor cells genetically engineered to produce monocyte chemoattractant protein-1 (MCP-1) have provided some encouragement. These studies have shown infiltration of certain types of lymphocytes at the tumor site. However, natural killer (NK) cells have not yet been assessed. We obtained a human malignant glioma cell line producing human MCP-1 constitutively by transfection of MCP-1 cDNA. We then test the effect of vaccination with the MCP-1 transfectant on nude mice. Although vaccination with MCP-1 transfectant did not reduce the tumor in our study, it was associated with the infiltration of large numbers of NK cells and monocytes at the tumor site. The site of vaccination also showed large numbers of monocytes. NK cells were detected with anti-asialo GM1 antibody, and monocytes were detected immunohistochemically with F4/80. We assumed that infiltrating monocytes at the site of vaccination could promote the infiltration of monocytes and NK cells into the tumor site without T-cell mediated transduction because the host lacked T-cell function.

Animals↗
PubMed2001

Fusion of MOZ and p300 histone acetyltransferases in acute monocytic leukemia with a t(8;22)(p11;q13) chromosome translocation.

Histone acetyltransferase p300 functions as a transcriptional co-activator which interacts with a number of transcription factors. Monocytic leukemia zinc finger protein (MOZ) has histone acetyltransferase activity. We report the fusion of the MOZ gene to the p300 gene in acute myeloid leukemia with translocation t(8;22)(p11;q13). FISH and Southern blot analyses showed the rearrangement of the MOZ and p300 genes. We determined the genomic structure of the p300 and the MOZ genes and the breakpoints of the translocation. Analysis of fusion transcripts indicated that the zinc finger and acetyltransferase domains of MOZ are fused to a largely intact p300. These results suggest that MOZ-p300, which has two acetyltransferase domains, could be involved in leukemogenesis through aberrant regulation of histone acetylation.

Acetyltransferases↗
PubMed2001

HTLV-I proviral load correlates with progression of motor disability in HAM/TSP: analysis of 239 HAM/TSP patients including 64 patients followed up for 10 years.

To clarify clinical and laboratory findings that may be related to the pathomechanism of HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP), we analyzed these findings in 239 patients with HAM/TSP, including 64 patients followed up for 10 years after their first examinations, with special interest in the HTLV-I proviral load in peripheral blood mononuclear cells (PBMCs). The proviral load in PBMCs did not differ in terms of modes of HTLV-I transmission. However, the proviral load in patients with age of disease onset greater than 65 years tended to be higher than those with a younger age of onset. In the 64 patients followed up for 10 years, the clinical symptoms deteriorated in 36 patients (56%), unchanged in 26 patients (41%), and improved in 2 patients (3%). HTLV-I proviral load also appeared to be related to the deterioration of motor disability in these patients. To our knowledge, the present study is the first longitudinal study concerning the relationship between the clinical course of HAM/TSP and HTLV-I proviral load. It is suggested that HTLV-I proviral load is related to the progression of motor disability and is an important factor to predict prognosis of patients with HAM/TSP.

Age of Onset↗
PubMed2001

Immunopathogenesis of human T cell lymphotropic virus type I-associated myelopathy.

Human T cell lymphotropic virus type I-associated myelopathy/tropical spastic paraparesis is a chronic progressive inflammatory neurological disease. Aspects of human T cell lymphotropic virus type I biology, host genetic susceptibility, and immune responses to this agent are important factors that are associated with disease progression. The use of novel immunological and molecular methods has improved our understanding of the pathophysiological mechanisms that are operative in human T cell lymphotropic virus type I-associated myelopathy/tropical spastic paraparesis. Co-existing high proviral loads and virus-specific CD8 T cells are important features of this disorder, in which a high cellular immune response continuously driven by this virus may contribute to the inflammatory process within central nervous system lesions in patients with this disease.

CD8-Positive T-Lymphocytes↗
PubMed2001

Expression of the p20 gene from Bacillus thuringiensis H-14 increases Cry11A toxin production and enhances mosquito-larvicidal activity in recombinant gram-negative bacteria.

Experimental analyses with recombinant Escherichia coli and Pseudomonas putida transformed with plasmids bearing genes coding for the Cry11A toxin and P20 protein from Bacillus thuringiensis H-14 showed that cells producing both proteins were more toxic when fed to third-instar Aedes aegypti larvae than were cells expressing cry11A alone; the 50% lethal concentrations were in the range of 10(4) to 10(5) cells/ml. Western blots revealed a higher production of Cry11A when the p20 gene was coexpressed. Cry11A was detected primarily in insoluble form in recombinant cells. Cry11A was not detected in P. putida when P20 was not coproduced, and these recombinants were not toxic to larvae, whereas P. putida recombinants producing both proteins were toxic at concentrations similar to those for E. coli. A coelution experiment was conducted, in which a p20 gene construct producing the P20 protein with an extension of six histidines on the C terminus was mixed with the Cry11A protein. The results showed that Cry11A bound to the P20(His(6)) on a nickel chelating column, whereas Cry11A produced without the P20(His(6)) protein was washed through the column, thus indicating that Cry11A and P20 physically interact. Thus, P20 protein either stabilizes Cry11A or helps it attain the folding important for its toxic activity.

Aedes↗
PubMed2001

Reciprocal protective immunity against Bordetella pertussis and Bordetella parapertussis in a murine model of respiratory infection.

The protective immunity induced by infection with Bordetella pertussis and with Bordetella parapertussis was examined in a murine model of respiratory infection. Convalescent mice that had been infected by aerosol with B. pertussis or with B. parapertussis exhibited a protective immune response against B. pertussis and also against B. parapertussis. Anti-filamentous hemagglutinin (anti-FHA) serum immunoglobulin G (IgG) and anti-FHA lung IgA antibodies were detected in both mice infected with B. pertussis and those infected with B. parapertussis. Antibodies against pertussis toxin (anti-PT) and against killed B. pertussis cells were detected in mice infected with B. pertussis. Pertactin-specific antibodies and antibodies against killed B. parapertussis cells were detected in mice infected with B. parapertussis. Spleen cells from mice infected with B. pertussis secreted interferon-gamma (IFN-gamma) in response to stimulation by FHA or PT. Spleen cells from mice infected with B. parapertussis also secreted IFN-gamma in response to FHA. Interleukin-4 was not produced in response to any of the antigens tested. The profiles of cytokine secretion in vitro revealed induction of a Th1-biased immune response during convalescence from infection by B. pertussis and by B. parapertussis. It is possible that Th1 and Th2 responses against FHA might be related to the reciprocal protection achieved in our murine model.

Adhesins, Bacterial↗
PubMed2001

Effects of fukinolic acid and cimicifugic acids from Cimicifuga species on collagenolytic activity.

The inhibitory collagenolytic activity (47-64% inhibition in 0.22-0.24 microM) of fukinolic acid and cimicifugic acids A, B, and C, which are esters of fukiic acid (3',4'-dihydroxybenzyl tartaric acid) was more potent than that (20-37% inhibition in 0.23-0.24 microM) of cimicifugic acids D, E, F, which are esters of pscidic acid (4'-hydroxybenzyl tartaric acid). Since fukiic acid showed weaker inhibition, and caffeic acid, ferulic acid, isoferulic acid, and p-coumaric acid showed far weaker activities, the entire structures of fukinolic acid and cimicifugic acids A, B, and C proved to be responsible for the inhibitory activities. Trypsin and pronase E hydrolyzed collagen nonselectively alone or in addition to collagenase. These collagenolytic activities were also inhibited by fukinolic acid. These results show that fukinolic acid may inhibit either the collagenolytic activities specific to collagenase or nonspecific to other emzymes. The present studies suggest the potential effect of fukinolic acid and cimicifugic acids of Cimicifuga rhizomes in preventing collagen degradation by collagenases or collagenolytic enzymes under pathological conditions, wound healing, or inflammation.

Caffeic Acids↗
PubMed2001

A stabilized flavonoid glycoside in heat-treated Cassia alata leaves and its structural elucidation.

Heat-treated leaves of Cassia alata were studied for any change in chemical constituents using sun dried leaves as the reference standard. A high concentration of a constituent was observed in the heat-treated leaves. Spectroscopic studies revealed the structure of the constituent as kaempferol 3-gentiobioside, which has not yet been detected in the Cassia species. In a stability study disappearance of kaempferol 3-gentiobioside was noted in the sun dried leaves while there was little or no change in the kaempferol 3-gentiobioside concentration in the heat-treated leaves when incubated in an aqueous solution, suggesting a possible presence of enzymatic activities in the sun dried leaves. Therefore, heat-treatment may be a good method to stabilize kaempferol 3-gentiobioside in Cassia alata leaves.

Cassia↗