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Biomedical subjects

T Takagi

Publications and source records attributed to T Takagi.

At least 271 records · Page 15Linked to original sources
PubMed1997

Molecular cloning of a novel polypeptide, DP5, induced during programmed neuronal death.

To study the molecular mechanisms underlying neuronal programmed cell death (PCD), we performed differential display screening for genes, the expression of which was induced during PCD in the sympathetic neuron culture model deprived of NGF. We cloned a gene encoding a novel polypeptide (DP5) which consisted of 92 amino acids. DP5 polypeptide had no homology with any other known protein and contained no motif that would indicate its putative biochemical functions. DP5 mRNA levels peaked at 15 h after nerve growth factor withdrawal, concurrent with the time at which neurons were committed to die. The induction of DP5 gene expression was blocked when cell death was rescued by treatment with cycloheximide, KCl, or the cyclic AMP analogue CPTcAMP. Overexpression of the full-length DP5 in cultured sympathetic neurons was in itself sufficient to induce apoptosis. These results suggest that DP5 plays a role in programmed neuronal death.

Amino Acid Sequence↗
PubMed1997

Cloning of a putative vesicle transport-related protein, RA410, from cultured rat astrocytes and its expression in ischemic rat brain.

To elucidate the role of astrocytes in the stress response of the central nervous system to ischemia, early gene expression was evaluated in cultured rat astrocytes subjected to hypoxia/reoxygenation. Using differential display, a novel putative vesicle transport-related factor (RA410) was cloned from reoxygenated astrocytes. Analysis of the deduced amino acid sequence showed RA410 to be composed of domains common to vesicle transport-related proteins of the Sec1/Unc18 family, including Sly1p and Sec1p (yeast), Rop (Drosophila), Unc18 (Caenorhabditis elegans), and Munc18 (mammalian), suggesting its possible role in vesicular transport. Northern analysis of normal rat tissues showed the highest expression of RA410 transcripts in testis. When astrocyte cultures were subjected to a period of hypoxia followed by reoxygenation, induction of RA410 mRNA was observed within 15 min of reoxygenation, reaching a maximum by 60 min. At the start of reoxygenation, the addition of diphenyl iodonium, an NADPH oxidase inhibitor, blocked in parallel astrocyte generation of reactive oxygen intermediates and expression of RA410 message. In contrast, cycloheximide did not affect RA410 mRNA levels, indicating that RA410 is an immediate-early gene in the setting of reoxygenation. Using polyclonal antibody raised against an RA410-derived synthetic peptide, Western blotting of lysates from reoxygenated astrocytes displayed an immunoreactive band of approximately 70 kDa, the expression of which followed induction of the mRNA. Fractionation of astrocyte lysates on sucrose gradients showed RA410 antigen to be predominantly in the plasma membrane. Immunoelectron microscopic analysis demonstrated RA410 in large vesicles associated with the Golgi, but not in the Golgi apparatus itself, consistent with its participation in post-Golgi transport. Consistent with these in vitro data, RA410 expression was observed in rat brain astrocytes following transient occlusion of the middle cerebral artery. These data provide insight into a new protein (RA410) that participates in the ischemia-related stress response in astrocytes.

Amino Acid Sequence↗
PubMed1997

An RNA 5'-triphosphatase related to the protein tyrosine phosphatases.

mRNA capping requires the sequential action of three enzymatic activities: RNA triphosphatase, guanylyl-transferase, and methyltransferase. Here we characterize a gene (CEL-1) believed to encode the C. elegans capping enzyme. CEL-1 has a C-terminal domain containing motifs found in yeast and vaccinia virus capping enzyme guanylyltransferases. The N-terminal domain of CEL-1 has RNA triphosphatase activity. Surprisingly, this domain does not resemble the vaccinia virus capping enzyme but does have significant sequence similarity to the protein tyrosine phosphatase (PTP) enzyme family. However, CEL-1 has no detectable PTP activity. The mechanism of the RNA triphosphatase is similar to that of PTPs: the active site contains a conserved nucleophilic cysteine required for activity. These results broaden the superfamily of PTP-like phosphatases to include enzymes with RNA substrates.

Acid Anhydride Hydrolases↗
PubMed1997

Impairment of T cell development in deltaEF1 mutant mice.

Using the method of gene targeting in mouse embryonic stem cells, regulatory function of deltaEF1, a zinc finger and homeodomain-containing transcription factor, was investigated in vivo by generating the deltaEF1 mutant mice. The mutated allele of deltaEF1 produced a truncated form of the deltaEF1 protein lacking a zinc finger cluster proximal to COOH terminus. The homozygous deltaEF1 mutant mice had poorly developed thymi with no distinction of cortex and medulla. Analysis of the mutant thymocyte showed reduction of the total cell number by two orders of magnitude accompanying the impaired thymocyte development. The early stage intrathymic c-kit+ T precursor cells were largely depleted. The following thymocyte development also seemed to be affected as assessed by the distorted composition of CD4- or CD8-expressing cells. The mutant thymocyte showed elevated alpha4 integrin expression, which might be related to the T cell defect in the mutant mice. In the peripheral lymph node tissue of the mutant mice, the CD4-CD8+ single positive cells were significantly reduced relative to CD4+CD8-single positive cells. In contrast to T cells, other hematopoietic lineages appeared to be normal. The data indicated that deltaEF1 is involved in regulation of T cell development at multiple stages.

Animals↗
PubMed1997

Augmented inhibitory effect of superoxide dismutase on superoxide anion release from macrophages by direct cationization.

Superoxide dismutase (SOD) was modified into cationized form (Cat-SOD) in order to enhance its pharmacological efficacy based on an electrostatic interaction. The inhibitory effect of Cat-SOD on superoxide anion release from inflammatory macrophages and its cellular interaction were studied in vitro. Cat-SOD exhibited an excellent inhibitory effect on superoxide anion release from the macrophages, and this effect surpassed those of native SOD and SOD modified with mannose (Man-SOD) which is taken up via mannose receptor-mediated endocytosis by macrophages. In the presence of colchicine, a microtubule-disruptive agent, the inhibitory effect of Cat-SOD was slightly impaired, whereas the effect of Man-SOD completely disappeared. The intracellular localization of fluorescein isothiocyanate-labeled SOD, Cat-SOD and Man-SOD observed by confocal laser microscopy supported the difference in their abilities to eliminate superoxide anions. The different sensitivities of Cat-SOD and Man-SOD to colchicine were also confirmed by the confocal laser microscopic images, suggesting their distinct intracellular trafficking pathways in the macrophages. In conclusion, Cat-SOD is desirable for its pharmacological activity, which is probably the result of its ability to be delivered to the vicinity of NADPH-oxidase which locates in the cell membrane and generates superoxide anions.

Animals↗
PubMed1997

Cloning and functional expression of a brain peptide/histidine transporter.

Here we report the cloning and functional characterization of a rat novel peptide/histidine transporter (PHT1), which was expressed in the brain and the retina. The cDNA encodes the predicted protein of 572 amino acid residues with 12 putative membrane-spanning domains. The amino acid sequence has moderate homology with a nonspecific peptide transporter found in the plant. When expressed in Xenopus laevis oocytes, PHT1 cRNA induced high affinity proton-dependent histidine transport activity. This transport process was inhibited by dipeptides and tripeptides but not by free amino acids such as glutamate, glycine, leucine, methionine, and aspartate. Dipeptide carnosine transport activity was also confirmed by direct uptake measurement. By in situ hybridization analysis, PHT1 mRNA was widely distributed throughout whole brain. Especially, intense hybridization signals were found in the hippocampus, choroid plexus, cerebellum, and pontine nucleus. Signals were located in both the neuronal and small nonneuronal cells in these areas. PHT1 protein could contribute to uptake of oligopeptides, which function as neuromodulators, and clearance of degraded neuropeptides and be a new member in the growing superfamily of proton-coupled peptide and nitrate transporters, although its structure, localization, and pharmacological characteristics are unique among these members.

Amino Acid Sequence↗
PubMed1997

Assessment of flail mitral leaflets by dynamic three-dimensional echocardiographic imaging.

To evaluate the usefulness of dynamic 3-dimensional images obtained by multiplane transesophageal echocardiography (TEE) in the diagnosis of the involved leaflets in patients with a flail mitral leaflet, 23 patients who underwent mitral valve repair were examined with multiplane TEE. In all patients, the involved lesions diagnosed by dynamic 3-dimensional images coincided with those confirmed at the time of operation; dynamic 3-dimensional images by multiplane transesophageal probe are useful in the evaluation of the involved sites in patients with a flail mitral leaflet.

Adult↗
PubMed1997

Modification of human left ventricular relaxation by small-amplitude, phase-controlled mechanical vibration on the chest wall.

BACKGROUND: Direct clinical manipulation to improve an impairment of left ventricular (LV) relaxation has not been reported. We investigated whether the LV relaxation rate in humans could be modulated by phase-controlled mechanical vibration applied to the patient's anterior chest wall and whether there are some quantitative differences in the responses of normal (N), hypertrophied (H), and failing (F) ventricle. METHODS AND RESULTS: In 46 patients (N, 10; H, 18 [hypertrophic cardiomyopathy]; F, 18 [heart failure]), the vibrator was attached to the precordium and a 50-Hz, 2-mm sinusoidal mechanical vibration was applied, with the timing restricted from the onset of isovolumic relaxation to end-diastole during cardiac catheterization. Heart rate and peak LV pressure showed no difference with vibration. However, in all patients, precordial vibration caused an acceleration of the LV pressure fall. The magnitude of the induced reduction of the time constant of LV pressure decay (delta T) was larger (P < .01) in H and F than in N (4.6 +/- 2.3, 4.0 +/- 1.6, and 0.6 +/- 1.5 ms for H, F, and N, respectively). Delta T correlated strongly with the magnitude of impaired relaxation and the magnitude of transmitted vibration to the ventricle. CONCLUSIONS: Phase-controlled, small-amplitude vibration on the chest wall can directly modulate LV relaxation rate, especially in those with hypertrophy or failing ventricle.

Adult↗
PubMed1997

The double-mirror gonioscopic lens for surgery of the anterior chamber angle.

Intraoperative examination of the anterior chamber angle is necessary during several glaucoma procedures, including goniosynechialysis and goniotomy. Many of the available lenses for this purpose are difficult to use because they require oblique illumination and their size interferes with surgical manipulations at the limbus. We have developed a double-mirror gonioscopic lens that uses direct illumination; provides an upright image of angle structures; and has a small diameter, allowing simultaneous access to the entire limbal region. We compared our lens with the Posner goniomirror (Ocular Instruments, Bellvue, Wash) and found that it provides an equal view of angle structures. The double-mirror gonioscopic lens facilitates the intraoperative visualization of the anterior chamber angle and should allow surgeons who treat glaucoma to more accurately and safely perform angle-related procedures.

Animals↗
PubMed1997

Capillary electrophoresis in presence of sodium dodecyl sulfate and a sieving medium.

For analysis of proteins in presence of sodium dodecyl sulfate (SDS), basic knowledge about their behavior in presence and absence of sieving medium is required. Capillary electrophoresis (CE) is particularly suitable for this purpose. Although various polymers are used as sieves in CE analysis in presence of SDS, attention must be paid to possible interaction between SDS and the polymer. For obtaining new insights polymers with defined molecular weight and distribution should be utilized.

Dextrans↗
PubMed1997

The effect of dexamethasone on the expression of activated NF-kappa B in adjuvant arthritis.

The transcription factor NF-kappa B plays a significant role in inflammatory diseases. In this study we have investigated the expression of activated NF-kappa B p65 subunit in the rat adjuvant arthritis model in a 28-day time-course experiment using immunohistochemistry. The expression of p65 was detected in the synovial lining layer and around the blood vessels in the inflamed synovium as early as Day 3 post-adjuvant injection. The cells that expressed p65 in the synovial lining were thought to be macrophage-like synoviocytes. The expression was stronger in the injected hindpaw than that in the noninjected hindpaw. Dexamethasone treatment at 1 mg/kg p.o. (Days 0-20) suppressed both the hindpaw edema and increase in p65 expression. Withdrawal of the treatment caused increases in both p65 expression and paw volume. Together these suggest that activated NF-kappa B was specifically expressed in the arthritic synovium and may play a significant role in the development of arthritis.

Animals↗
PubMed1997

Changes in bone mineral density in rat adjuvant arthritis.

This study demonstrates that systemic and local decreases in bone mineral density (BMD) occurred with Freund's complete adjuvant injection in the rat right footpad using dual energy X-ray absorptiometry. The rats were assigned to either adjuvant-treated or non-treated control groups composed of eight animals each. There was significant decrease in BMD in the adjuvant group compared to the control group at the distal region of femur or proximal region of tibia on Day 7 post-adjuvant injection (P < 0.05). On the other hand, the femur or tibia of the noninjected side showed a smaller and delayed decrease in BMD than did the injected side. These decreases in BMD were seen in not only the trabecular but also the cortical bone. In addition, the vertebrae also showed delayed but significant decrease (P < 0.05) in BMD on Day 21.

Animals↗
PubMed1997

A de novo recombination in the ABO blood group gene and evidence for the occurence of recombination products.

We have encountered a paternity case where exclusion of the putative father was only observed in the ABO blood group (mother, B; child, A1; putative father, O), among the many polymorphic markers tested, including DNA fingerprints and microsatellite markers. Cloning a part of the ABO gene, PCR-amplified from the trio's genomes, followed by sequencing the cloned fragments, showed that one allele of the child had a hybrid nature, comprising exon 6 of the B allele and exon 7 of the O1 allele. Based on the evidence that exon 7 is crucial for the sugar-nucleotide specificity of A1 and B transferases and that the O1 allele is only specified by the 261G deletion in exon 6 of the consensus sequence of the A1 allele, we concluded that the hybrid allele encodes a transferase with A1 specificity, resulting, presumably, from de novo recombination between the B and O1 alleles of the mother during meiosis. Screening of random populations demonstrated the occurrence of four other hybrid alleles. Sequencing of intron VI from the five hybrid alleles showed that the junctions of the hybrid alleles were located within intron VI, the intron VI-exon 7 boundaries, or exon 7. Recombinational events seem to be partly involved in the genesis of sequence diversities of the ABO gene.

ABO Blood-Group System↗
PubMed1997

Serum vitamin K level and bone mineral density in post-menopausal women.

OBJECTIVE: Vitamin K is known to influence bone metabolism by facilitating the synthesis of osteocalcin (BGP). The bone mineral density decreases drastically after menopause. We investigated the relationship of bone mineral density, vitamin K levels and other biological parameters of bone metabolism in post-menopausal women. METHODS: Serum levels of vitamin K, BGP and other markers of bone metabolism were measured in 71 post-menopausal women (19 with reduced bone mineral density and 52 with normal bone density), and 24 women with climacteric symptoms receiving hormone replacement therapy (HRT), (6 with reduced bone mineral density and 18 with normal density). RESULTS: In the first group, women with reduced bone mineral density showed lower levels of vitamin K1 and K2 than those with normal bone mineral density. In the other group, the level of BGP decreased but levels of vitamin K showed no increase during HRT. CONCLUSION: The present findings suggested that vitamin K was related to post-menopausal bone mineral loss.

Bone Density↗