PubMed Health⌕ Search

Biomedical subjects

F Taguchi

Publications and source records attributed to F Taguchi.

At least 19 recordsLinked to original sources
PubMed2003

The DeltafliD mutant of Pseudomonas syringae pv. tabaci, which secretes flagellin monomers, induces a strong hypersensitive reaction (HR) in non-host tomato cells.

To investigate the role of flagella and monomer flagellin in the interaction between Pseudomonas syringae pv. tabaci and plants, non-polar fliC and fliD mutants were produced. The ORFs for fliC and fliD are deleted in the DeltafliC and DeltafliD mutants, respectively. Both mutants lost all flagella and were non-motile. The DeltafliC mutant did not produce flagellin, whereas the DeltafliD mutant, which lacks the HAP2 protein, secreted large amounts of monomer flagellin into the culture medium. Inoculation of non-host tomato leaves with wild-type P. syringae pv. tabaci or the DeltafliD mutant induced a hypersensitive reaction (HR), whereas the DeltafliC mutant propagated and caused characteristic symptom-like changes. In tomato cells in suspension culture, wild-type P. syringae pv. tabaci induced slight, visible HR-like changes. The DeltafliC mutant did not induce HR, but the DeltafliD mutant induced a remarkably strong HR. Expression of the hsr203J gene was rapidly and strongly induced by inoculation with the DeltafliD mutant, compared to inoculation with wild-type P. syringae pv. tabaci. Furthermore, introduction of the fliC gene into the DeltafliC mutant restored motility and HR-inducing ability in tomato. These results, together with our previous study, suggest that the flagellin monomer of pv. tabaci acts as a strong elicitor to induce HR-associated cell death in non-host tomato cells.

Bacterial Outer Membrane Proteins↗
PubMed2001

Neurovirulence in mice of soluble receptor-resistant (srr) mutants of mouse hepatitis virus: intensive apoptosis caused by less virulent srr mutant.

Three soluble receptor-resistant (srr) mutants, srr7, srr11 and srr18, derived from a highly neurotropic mouse hepatitis virus (MHV) JHMV have a single amino acid mutation in the spike (S) protein. We examined using ICR mice whether the amino acids mutated in the mutants were involved in the neurovirulence. Srr7 showed apparently reduced neurovirulence relative to the wild-type (wt) JHMV in terms of the LD50 and survival time, while the others showed slightly reduced virulence. In the brain and spinal cord, the growth of srr7 was more than 2 log10 lower than that of the wt virus. Histopathologically, no significant difference was revealed between wt and srr7-infected mice on day 2 postinoculation (p.i.), with only scant inflammation and a minimum degree of neuropathological changes. The major difference was that apoptotic cells were frequently encountered in the srr7-infected mouse brain, but not in wt-infected mice on day 2 p.i. However, there was no difference between these viruses in the potential to induce apoptosis in cultured cells. The apoptosis in the brain did not appear to result from the direct viral attack, since apoptotic cells were found in the lesion where viral antigens were barely detected. The present study suggests that the amino acids mutated in the S protein of srr mutants, especially the amino acid at position 1114 mutated in srr7, influence the neurovirulence in mice.

Animals↗
PubMed2001

Effect of methyl jasmonate on harpin-induced hypersensitive cell death, generation of hydrogen peroxide and expression of PAL mRNA in tobacco suspension cultured BY-2 cells.

Methyl jasmonate inhibited the harpin-induced defense responses such as cell death, H2O2 generation and gene expression encoding phenylalanine ammonia-lyase in tobacco suspension cultured BY-2 cells. These results suggest that MeJA may act as an endogenous suppressor for plant defense response including hypersensitive reaction.

Acetates↗
PubMed2000

Impaired entry of soluble receptor-resistant mutants of mouse hepatitis virus into cells expressing MHVR2 receptor.

Mouse hepatitis virus (MHV) JHMV and its soluble receptor-resistant (srr) mutants, srr7, srr11, and srr18, grew and induced syncytia equally well in BHK-R1 cells expressing the MHVR1 receptor derived from MHV-susceptible BALB/c mice. In contrast, srr growth and syncytia formations were drastically reduced relative to wild-type (wt) virus in BHK-R2 cells expressing the MHVR2 receptor from MHV-resistant SJL mice. Infections by these srr mutants in BHK-R2 cells were 0.7 to 1.5 log10 less efficient than those of wt virus. BHK cells expressing both MHVR1 and MHVR2 supported srr replication to the same extent as did BHK-R1 cells, suggesting that inefficient infection by srr mutants in BHK-R2 cells resulted from the absence of the effective receptor MHVR1. Virus-receptor binding tests failed to demonstrate a difference between the abilities of wt and srr18 to bind MHVR2. The binding of srr7 and srr11 to both MHVR1 and MHVR2 was revealed lower by two- to fourfold relative to the wt binding. The fusion activity of srr S proteins as examined by the expression with recombinant vaccinia virus was apparently lower than that of the wt S protein in BHK-R2 cells, while there was not such a remarkable difference in BHK-R1 cells. This suggests that the most likely reason for inefficient infection by mutants in BHK-R2 is impaired virus entry into cells. These observations suggest that inefficient infections in BHK-R2 cells by srr mutants occur in the absence of a functional receptor MHVR1, which plays an important role in srr entry into cells.

Animals↗
PubMed2000

Protective effects of murine recombinant interferon-beta administered by intravenous, intramuscular or subcutaneous route on mouse hepatitis virus infection.

The significance of the route for administration of murine recombinant interferon-beta (IFN-beta) for inducing its therapeutic effects has been studied. BALB/c mice were daily injected intravenously, intramuscularly or subcutaneously with 1.5x10(3), 1. 5x10(4), or 1.5x10(5) IU of IFN-beta, from one day before to 8th day after mouse hepatitis virus (MHV-2) challenge. All mice received IFN-beta survived significantly longer than those without IFN. In the liver of those IFN-treated mice, viral growth and the histopathological damages were extremely alleviated. These results suggest that, irrespective of the differences in the route of administration, IFN-beta markedly suppressed viral activity when its administration was started prior to viral infection. For clinical use, however, further studies are needed on the optimal route for administration if IFN-beta is given after viral infection.

Animals↗
PubMed2000

Unique N-linked glycosylation of murine coronavirus MHV-2 membrane protein at the conserved O-linked glycosylation site.

The membrane (M) proteins of murine coronavirus (MHV) strains have been reported to contain only O-linked oligosaccharides. The predicted O-glycosylation site consisting of four amino acid residues of Ser-Ser-Thr-Thr is located immediately adjacent to the initiator Met and is well conserved among MHV strains investigated so far. We analyzed the nucleotide sequence of a highly virulent strain MHV-2 M-coding region and demonstrated that MHV-2 had a unique amino acid, Asn, at position 2 at the conserved O-glycosylation site. We also demonstrated that this substitution added N-linked glycans to MHV-2 M protein resulting in increment of molecular mass of MHV-2 M protein compared with JHM strain having only O-linked glycans.

Amino Acid Sequence↗
PubMed1999

Difference in Bgp-independent fusion activity among mouse hepatitis viruses.

Mouse hepatitis virus (MHV) utilizes a mouse biliary glycoprotein (Bgp) as a receptor. Co-cultivation of MHV-nonpermissive hamster BHK cells devoid of mouse Bgp with mouse DBT cells infected with MHV-A59 or JHMV induces syncytia formation on BHK cells (Bgp-independent fusion). This study shows the difference in Bgp-independent fusion activity among various MHV strains. Under a phase contrast microscopy, JHMV (cl-2, sp-4) induced the Bgp-independent syncytia on BHK cells similar to those observed on DBT cells, while such syncytia were not seen with the infection of other MHV strains (MHV-1, MHV-3, MHV-A59, MHV-S, srr7, srr11 and srr18). Tiny syncytia detectable only by immunofluorescence were produced with the latter MHV strains except for srr7 which failed to produce syncytia. MHVs except for srr7 grew in BHK cells after Bgp-independent infection. The Bgp-independent fusion by JHMV was inhibited either by anti-S1 or anti-S2 antibodies. These results showed that the JHMV spike protein had a remarkably high Bgp-independent fusion activity.

Animals↗
PubMed1999

Type A behavior is associated with an increased risk of left ventricular hypertrophy in male patients with essential hypertension.

OBJECTIVE: To determine whether type A behavior, which is associated with a risk of coronary heart disease, affects left ventricular hypertrophy in patients with essential hypertension. DESIGN: Cross-sectional study of 88 untreated patients with mild to moderate essential hypertension (33 men, mean +/- SEM age 54 +/- 1 years). METHODS: We measured the type A behavior score using a standardized questionnaire, left ventricular mass index using M-mode echocardiography and 24 h mean ambulatory blood pressure (recorded every 30 min). Beat-to-beat blood pressure was also measured using a Finapres device in patients at rest and during mental stress (counting backward) to determine the blood pressure response to stress. RESULTS: The left ventricular mass index was correlated with the type A behavior score (r = 0.214, P < 0.05), age (r = 0.266, P < 0.05), 24 h mean systolic and diastolic blood pressures (r = 0.391, P < 0.001, and r = 0.382, P < 0.001, respectively), systolic blood pressure both at rest and during stress (r = 0.255, P < 0.05, and r = 0.215, P < 0.05, respectively), and the variability of both systolic and diastolic blood pressures at rest (r = 0.253, P < 0.05, and r = 0.321, P < 0.01, respectively). Stepwise multiple linear regression analysis demonstrated that age was associated with an increase in the left ventricular mass index for both sexes (P = 0.004 for males, P = 0.003 for females). The type A behavior score predicted a greater increase in left ventricular mass index in men (P = 0.018) but not in women. The 24 h mean systolic blood pressure was associated with a greater increase in left ventricular mass index in women (P < 0.001) but not in men. CONCLUSION: Type A behavior is an independent risk factor for left ventricular hypertrophy in male patients with essential hypertension.

Blood Pressure↗
PubMed1998

Differential receptor-functionality of the two distinct receptor proteins for mouse hepatitis virus.

We compared the virus-binding activity and receptor-functionality of the receptor proteins isolated from mouse hepatitis virus (MHV)-susceptible BALB/c mice (MHVR1) and MHV-resistant SJL mice (MHVR2). By using a soluble receptor protein which lacked the transmembrane and intracytoplasmic domains, virus overlay protein blot assay and neutralization tests showed that MHVR1 bound to JHM cl-2 virus with 300-500 times higher efficiency than to MHVR2. MHVR1 was revealed to have 10-30 fold higher receptor-functionality than MHVR2 when examined by measuring virus-binding to the receptor expressed on the cell surface. These findings suggested that the differences in susceptibility between BALB/c and SJL mice may depend upon the genotype of the MHV receptor.

Animals↗
PubMed1998

Requirement of proteolytic cleavage of the murine coronavirus MHV-2 spike protein for fusion activity.

The spike (S) protein of a non-fusogenic murine coronavirus, MHV-2, was compared to that of a variant, MHV-2f, with fusion activity. Two amino acids differed between The S proteins of these viruses; one was located in the signal sequence (amino acid 12) and the other in the putative cleavage site (amino acid 757). To determine which one of these amino acid changes is important for the alteration of fusogenicity, chimeric S proteins between MHV-2 and -2f were constructed and expressed in DBT cells by a vaccinia virus expression system. The results revealed that one amino acid change (Ser to Arg) at position 757 is responsible for the acquisition of fusogenicity of the MHV-2f S protein. This change also altered the susceptibility to proteolytic cleavage of the MHV-2 S protein which was originally uncleavable. We concluded that the non-fusogenic activity of MHV-2 results from the lack of cleavage of its S protein.

Animals↗
PubMed1998

Isolation and characterization of murine coronavirus mutants resistant to neutralization by soluble receptors.

Murine coronavirus mutants resistant to neutralization with soluble receptors were isolated to study the receptor-binding site on the S proteins since such mutants were expected to have mutations in an important site for receptor-binding. We have isolated five soluble receptor-resistant (srr) mutants which had mutations of a single amino acid at 3 different positions in S protein. Srr mutant 11 with an amino acid change at position 65 (Leu to His) in the S1 subunit showed an extremely reduced binding by virus overlay protein blot assay. However srr mutants with a mutation at 1114 (Leu to Phe) (srr mutants 3, 4 and 7) or 1163 (Cys to Phe) (srr mutant 18) in the S2 subunit had receptor-binding activity similar to that of wild type cl-2. These results suggest that an amino acid at position 62 located in a conserved region among MHV strains is in particular important for receptor binding. We also discuss why srr mutants with a mutation in S2 showed high resistance to neutralization by soluble receptor, irrespective of their binding to MHV receptors.

Animals↗
PubMed1998

Psychobehavioral factors involved in the isolated office hypertension: comparison with stress-induced hypertension.

OBJECTIVE: To investigate the psychobehavioral factors involved in the isolated clinic blood pressure elevation and hypertension induced by mental stress. DESIGN AND METHODS: We studied 73 untreated patients with essential hypertension defined as World Health Organization stage I or II (28 men and 45 women, mean age 55 +/- 11 years). The amount of isolated clinic blood pressure elevation was examined in terms of the difference between clinic and daytime ambulatory blood pressures. Blood pressure (measured using a Finapres device) and R-R interval (measured electrocardiographically) were continuously monitored with subjects at rest and under mental stress (counting backward) to examine the cardiovascular response to the stress. Psychobehavioral characteristics such as anger, anxiety, tension, type A behavior pattern, and nervousness were evaluated and scored using structured interviews and self-reporting questionnaires. RESULTS: The anger score was inversely correlated to the clinic-ambulatory blood pressure difference for the systolic (r = -0.308, P < 0.01) and diastolic (r = -0.233, P < 0.05) blood pressures. The score for type A behavior pattern tended to be inversely correlated to the clinic-ambulatory blood pressure difference for diastolic blood pressure (r = -0.209, P < 0.1). The nervousness score was positively correlated to stress-induced increase in the systolic (r = 0.249, P < 0.05) and diastolic (r = 0.232, P < 0.05) blood pressures. The clinic-ambulatory blood pressure difference was not related to the blood pressure rise induced by mental stress (r = 0.170 for systolic blood pressure; r = 0.112 for diastolic blood pressure). CONCLUSION: The isolated clinic blood pressure elevation and hypertension due to mental stress were related to different psychobehavioral factors.

Adult↗