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Biomedical subjects

A Takada

Publications and source records attributed to A Takada.

At least 73 records · Page 4Linked to original sources
PubMed1999

Larger and more invasive colorectal carcinoma contains larger amounts of plasminogen activator inhibitor type 1 and its relative ratio over urokinase receptor correlates well with tumor size.

BACKGROUND: Considering recent findings that both urokinase plasminogen activator receptor (uPAR) and plasminogen activator inhibitors (PAIs) are involved in tumor growth through an urokinase-type plasminogen activator (uPA) activity-independent mechanism, the relation between the presence of these factors in tumor tissue and the clinicopathologic variables in colorectal carcinoma was reevaluated. METHODS: In 100 colorectal carcinoma patients, antigen levels of u-PA, uPAR, and PAI-1 and PAI-2 were assayed in both tumor tissues and their normal counterparts. Plasma levels of soluble uPAR also were determined. RESULTS: All uPAR, uPA, PAI-1, and PAI-2 antigen levels in tumor tissue were significantly higher than those in normal tissue. Levels of both uPAR and PAI-1 were significantly higher (3.09 +/- 1.37 and 6.63 +/- 7.49, respectively) in large tumors (>/=50 mm in greatest dimension) than those in smaller tumors (< 50 mm) (2.50 +/- 1.07 and 2.72 +/- 2.70, respectively) (P < 0.05). Significant positive correlation coefficients (r) were obtained between tumor size and the calculated ratios of PAI-1/uPAR (r = 0.490; P < 0.0001) and PAI-1/uPA (r = 0. 469; P < 0.0001). In addition to liver metastases (P = 0.004) and lymph node involvement (P = 0.04), high levels of uPAR (P = 0.05) also were found to be of independent prognostic value by multivariate analysis. CONCLUSIONS: Higher expression of uPAR was related to poor prognosis of patients with colorectal carcinoma and excess amounts of PAI-1 over uPAR or uPAR-bound uPA appeared to play an important role in tumor progression.

Adult↗
PubMed1999

Antithrombotic activity of avian crown dermatan sulfate.

The antithrombotic activity of dermatan sulfate from avian crown with the mean molecular weight of 38000 was compared to those from bovine intestine with the mean molecular weight of 16000 in vivo and in vitro. In an in vitro test, bovine intestine dermatan sulfate exhibited stronger effects on stimulation of heparin cofactor II and activation of Glu-plasminogen by tissue plasminogen activator. In vivo, avian crown dermatan sulfate more effectively prevented the development of thrombus in a rat deep vein thrombosis model. The measurement of plasma levels of these two kinds of dermatan sulfate revealed that avian crown dermatan sulfate circulated in higher concentration and longer duration than bovine intestine dermatan sulfate after intravenous administration to rats.

Animals↗
PubMed1999

Overproduction of the outer-membrane proteins FepA and FhuE responsible for iron transport in Escherichia coli hfq::cat mutant.

We found that 82- and 76-kDa proteins in the outer-membrane fractions were overproduced in the hfq::cat mutant cells when grown in synthetic media. Expression of these proteins was repressed by addition of FeCl(3) in the mutant as well as in the wild type. It was revealed that these are FepA and FhuE proteins involved in iron transport. The hfq::cat mutant was more susceptible to killing by hydrogen peroxide, probably due to the excess incorporation of iron, which potentially generates hydroxyl radicals. Increased incorporation of iron in the hfq::cat mutant was also confirmed by the suppressive effect on the ftsH1 mutation. These results suggest that the hfq gene product is involved in the defense mechanism against oxidative stress.

Bacterial Outer Membrane Proteins↗
PubMed1999

Induction of antibodies in mice by a recombinant baculovirus expressing pseudorabies virus glycoprotein B in mammalian cells.

The glycoprotein gB of pseudorabies virus (PrV) was expressed in various mammalian cells by a recombinant baculovirus carrying the PrV gB gene under the control of the CAG promoter. When the recombinant baculovirus was inoculated into the stable porcine kidney cell line CPK, expression of PrV gB was detected by immunofluorescent antibody analysis and a 155 kDa of protein, which has the same molecular mass as the native PrV gB, was detected by Western blotting. High levels of expression of PrV gB were observed in BHK-21, HmLu-1 and SK-H cell lines. Furthermore, anti-PrV gB-specific antibodies against PrV gB protein were detected by the enzyme-linked immunosorbent assay in mice inoculated the recombinant baculovirus. The recombinant baculovirus containing the PrV glycoprotein gB gene under the CAG promoter could be a candidate for a pseudorabies vaccine.

Animals↗
PubMed1999

Escherichia coli cafA gene encodes a novel RNase, designated as RNase G, involved in processing of the 5' end of 16S rRNA.

We found that the Escherichia coli cafA::cat mutant accumulated a precursor of 16S rRNA. This precursor migrated to the same position with 16.3S precursor found in the BUMMER strain that is known to be deficient in the 5' end processing of 16S rRNA. Accumulation of 16. 3S rRNA in the BUMMER mutant was complemented by introduction of a plasmid carrying the cafA gene. The mutant type cafA gene cloned from the BUMMER strain had a 11-bp deletion in its coding region. A small amount of the mature 16S rRNA was still formed in the cafA::cat mutant. This residual activity was found to be due to RNase E encoded by the rne/ams gene by rifampicin-chase experiments of the cafA::cat ams1 double mutant. These results indicated that the cafA gene encodes a novel RNase responsible for processing of the 5' end of 16S rRNA.

Bacterial Proteins↗
PubMed1999

Structure of the immediate early gene of canine herpesvirus.

The nucleotide sequence of the immediate early (IE) gene of canine herpesvirus was determined. This gene was located in the inverted repeat regions, encoding a polypeptide of 1,383 amino acids. The predicted amino acid sequence was most closely related to that of the feline herpesvirus 1 IE protein among those of other alphaherpesviruses. DNA binding and transcriptional activation domains were found in the IE protein. A spliced region of the IE gene transcript was determined in its 5' non-coding region.

Amino Acid Sequence↗
PubMed1999

Differential effects of enalapril and nitrendipine on the fibrinolytic system in essential hypertension.

BACKGROUND: Impaired fibrinolysis is associated with thromboembolic complications in hypertensive patients. It has been reported that cardiovascular morbidity and mortality rates are high even after lowering the elevated blood pressure with antihypertensive drugs. The aim of this study was to assess the effect of clinically used dosages of enalapril and nitrendipine on the fibrinolytic system. METHODS: Tissue plasminogen activator antigen (tPA) and tissue plasminogen activator inhibitor-1 (PAI-1) activity were measured in 20 normotensive male subjects and 46 male patients with mild essential hypertension divided into 2 groups (22 patients treated with 5 to 10 mg enalapril once a day and 24 treated with 5 to 10 mg nitrendipine once a day) before and 3 months after drug administration. Plasma renin activity and norepinephrine concentration were also measured. RESULTS: There were no significant differences in basal characteristics between the 2 hypertensive groups. In both hypertensive groups, blood pressure was significantly reduced to a similar level after drug treatment. In the 2 hypertensive groups, plasma renin activity significantly increased after drug treatment; however, there were no significant changes in norepinephrine concentration. Before drug treatment, the 2 hypertensive groups had significantly higher tPA and higher PAI-1 activity than the normotensive subjects. In the enalapril group, there was no significant change in tPA although PAI-1 activity significantly decreased after drug treatment. In the nitrendipine group, there was no significant change in tPA although PAI-1 activity significantly increased after drug treatment. CONCLUSION: Thus enalapril improved impaired fibrinolysis but nitrendipine further aggravated fibrinolysis in essential hypertension. Considering the effect of antihypertensive drugs on the fibrinolytic system, more effective and beneficial treatment of hypertensives, especially at a high risk for thrombus formation might be selected.

Administration, Oral↗
PubMed1999

Proteolysis of neuronal cell adhesion molecule by the tissue plasminogen activator-plasmin system after kainate injection in the mouse hippocampus.

Tissue plasminogen activator (tPA) is a serine protease that converts inactive plasminogen to the active protease plasmin and mediates extracellular metabolism. tPA is transcriptionally induced in the mouse hippocampus by pharmacological or electrical stimulation of neuronal activity and mediates excitotoxin-induced neuronal degeneration. Therefore, we hypothesized that tPA would be induced in the hippocampus after kainic acid (KA) injection into the lateral cerebral ventricle (LCV) and that the activated tPA-plasmin system would degrade the neuronal cell adhesion molecule (NCAM), which is a component of the extracellular matrix. In order to investigate this possibility, we first examined whether NCAM is a substrate for the tPA plasmin system by incubating mouse brain homogenates with tPA and plasminogen at 37 degrees C. Next, we examined the degradation of NCAM and the changes of tPA activity in the mouse hippocampus with immunohistochemical procedures and histological zymography after KA injection into both LCVs. As a result, we observed neuronal atrophy and a decrease of NCAM immunoreactivity along with an increase of tPA activity in the CA3 area of the hippocampus. These results suggest that activation of the tPA plasmin system after KA injection into the LCVs results in the degradation of NCAM in the CA3 area.

Animals↗
PubMed1999

Neuronal degeneration and a decrease in laminin-like immunoreactivity is associated with elevated tissue-type plasminogen activator in the rat hippocampus after kainic acid injection.

Tissue-type plasminogen activator (tPA) is a serine protease that converts the inactive precursor plasminogen to the active protease plasmin. In the central nervous system, tPA has been suggested to participate in plasticity, memory and the neuronal degeneration caused by excitotoxins, but its precise functions during these processes are still unclear. We show in this report that tPA antigen level and extracellular tPA activity increased in the hippocampus during the early stages of neuronal degeneration in the CA3 region following the injection of kainic acid (KA) into the lateral cerebral ventricles. The increase in tPA antigen level was transient and its peak was at 4 h after the injection. tPA activity was also increased 4 h after the injection, but it remained at a high level for more than 8 h. Histological zymography showed that the increase in tPA activity was mainly localized in the CA3 region. In the same region, the disappearance of interneuronal laminin-like immunoreactivity and atrophic changes in pyramidal neurons were observed 4 h after the injection of KA. These results suggested that such focal and transient increases in tPA synthesis and release, which result in the proteolysis of laminin through plasminogen activation, could be involved in the neuronal degeneration in the CA3 region after the injection of KA.

Animals↗
PubMed1999

The effects of stimulus rates on the amplitude of median nerve somatosensory evoked potentials: the developmental change.

We examined the effects of stimulus rates on the somatosensory evoked potential (SEP) amplitudes following median nerve stimulation at the wrist in 42 children. We divided these subjects into five groups according to their age (0-6 months, 7-12 months, 1-3 years, 4-6 years and more than 7 years) and measured the peak-to-peak amplitude of every component (N9, P10, N11, P13/14, N18, N20, P23, N30) at stimulus rates of 1.0, 3.5 and 5.5 Hz. From N9 to N18, there was no significant change in amplitude nor latency with stimulus rate change in all groups. The amplitude attenuation was found at the N20 and N30 peaks in the young group (0 months to 3 years) and at P23 in all groups with an increasing stimulus rate. The attenuation rate of P23 amplitude was influenced by the age of subjects, being greater in younger groups and greatest in the youngest group (0-6 months). The differences of amplitude attenuation rate between this group and the rest were statistically significant. The results of this study indicate that the amplitudes of the cortical components of SEP in children are greatly influenced by the stimulus rate. Thus when we discuss the amplitude of cortical waves in childhood, we should also pay attention to the stimulus rates.

Aging↗
PubMed1999

Avirulent Avian influenza virus as a vaccine strain against a potential human pandemic.

In the influenza H5N1 virus incident in Hong Kong in 1997, viruses that are closely related to H5N1 viruses initially isolated in a severe outbreak of avian influenza in chickens were isolated from humans, signaling the possibility of an incipient pandemic. However, it was not possible to prepare a vaccine against the virus in the conventional embryonated egg system because of the lethality of the virus for chicken embryos and the high level of biosafety therefore required for vaccine production. Alternative approaches, including an avirulent H5N4 virus isolated from a migratory duck as a surrogate virus, H5N1 virus as a reassortant with avian virus H3N1 and an avirulent recombinant H5N1 virus generated by reverse genetics, have been explored. All vaccines were formalin inactivated. Intraperitoneal immunization of mice with each of vaccines elicited the production of hemagglutination-inhibiting and virus-neutralizing antibodies, while intranasal vaccination without adjuvant induced both mucosal and systemic antibody responses that protected the mice from lethal H5N1 virus challenge. Surveillance of birds and animals, particularly aquatic birds, for viruses to provide vaccine strains, especially surrogate viruses, for a future pandemic is stressed.

Animals↗
PubMed1999

Identification of the murine Mx2 gene: interferon-induced expression of the Mx2 protein from the feral mouse gene confers resistance to vesicular stomatitis virus.

The mouse genome contains two related interferon-regulated genes, Mx1 and Mx2. Whereas Mx1 codes for the nuclear 72-kDa protein that interferes with influenza virus replication after interferon treatment, the Mx2 gene is nonfunctional in all laboratory mouse strains examined, since its open reading frame (ORF) is interrupted by an insertional mutation and a subsequent frameshift mutation. In the present study, we demonstrate that Mx2 mRNA of cells from feral mouse strains NJL (Mus musculus musculus) and SPR (Mus spretus) differs from that of the laboratory mouse strains tested. The Mx2 mRNA of the feral strains contains a single long ORF consisting of 656 amino acids. We further show that Mx2 protein in the feral strains is expressed upon interferon treatment and localizes to the cytoplasm much like the rat Mx2 protein, which inhibits vesicular stomatitis virus replication. Furthermore, transfected 3T3 cell lines of laboratory mouse origin expressing Mx2 from feral strains acquire slight resistance to vesicular stomatitis virus.

Amino Acid Sequence↗
PubMed1999

fcsA29 mutation is an allele of polA gene of Escherichia coli.

The cold-sensitive fcsA29 mutation of Escherichia coli was found to be a new type of cold-sensitive allele of the polA gene encoding DNA polymerase I, caused by an Asp(116)-->Asn change in the 5'-->3' exonuclease domain. The fcsA29 mutant showed typical polA mutant phenotypes such as UV sensitivity and unacceptability of recA mutation. Cold-sensitive growth of the mutant was suppressed by introduction of a sulA mutation, indicating that cell filamentation was due to the SOS response.

Alleles↗
PubMed1999

Detection of canine herpesvirus DNA in the ganglionic neurons and the lymph node lymphocytes of latently infected dogs.

To determine the site of latent infection of canine herpesvirus (CHV), tissues from dogs convalescent from acute infection with CHV were examined for the presence of viral genome DNA by the nested polymerase chain reaction. CHV DNA was detected in the trigeminal ganglia and the retropharyngeal lymph nodes. In situ hybridization study of the tissues revealed that CHV genome persisted in the nuclei of ganglionic neurons and lymphocytes.

Animals↗
PubMed1999

The activation of the tissue plasminogen activator-plasmin system induced in the mouse hippocampus after injection of trimethyltin: possible proteolysis of highly polysialylated NCAM.

Trimethyltin (TMT) is a neurotoxicant that causes the death of granule cells and degrades highly polysialylated NCAM (PSA-NCAM) in the dentate gyrus. To investigate the role of the tPA-plasmin system in the degradation of PSA-NCAM, we injected trimethyltin (TMT) into mice. As a result, tPA activity was significantly increased in CA1-CA4 and the dentate gyrus after TMT injection. These results suggest that up-regulated tPA may contribute to the degradation of PSA-NCAM.

Animals↗
PubMed1999

Antigenic and genetic analyses of H5 influenza viruses isolated from ducks in Asia.

The hemagglutinin (HA) of six H5 influenza virus strains isolated from ducks in Japan and China in 1976 to 1996 were analyzed antigenically and genetically. Antigenic analysis using a panel of monoclonal antibodies revealed that the HA of H5 influenza viruses isolated from ducks are antigenically closely related to each other. Phylogenetic analysis indicates that the isolates from ducks in Hokkaido were derived from an ancestor common with the highly pathogenic isolates from chickens and humans in Hong Kong in 1997.

Animals↗