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Biomedical subjects

Y Takagi

Publications and source records attributed to Y Takagi.

At least 145 records · Page 8Linked to original sources
PubMed1999

The elongin B ubiquitin homology domain. Identification of Elongin B sequences important for interaction with Elongin C.

Mammalian Elongin B is a 118-amino acid protein composed of an 84-amino acid amino-terminal ubiquitin-like domain and a 34-amino acid carboxyl-terminal tail. Elongin B is found in cells as a subunit of the heterodimeric Elongin BC complex, which was originally identified as a positive regulator of RNA polymerase II elongation factor Elongin A and subsequently as a component of the multiprotein von Hippel-Lindau tumor suppressor and suppressor of cytokine signaling complexes. As part of our effort to understand how the Elongin BC complex regulates the activity of Elongin A, we are characterizing Elongin B functional domains. In this report, we show that the Elongin B ubiquitin-like domain is necessary and sufficient for interaction with Elongin C and for positive regulation of Elongin A transcriptional activity. In addition, by site-directed mutagenesis of the Elongin B ubiquitin-like domain, we identify a short Elongin B region that is important for its interaction with Elongin C. Finally, we observe that both the ubiquitin-like domain and carboxyl-terminal tail are conserved in Drosophila melanogaster and Caenorhabditis elegans Elongin B homologs that efficiently substitute for mammalian Elongin B in reconstitution of the transcriptionally active Elongin ABC complex, suggesting that the carboxyl-terminal tail performs an additional function not detected in our assays.

Amino Acid Sequence↗
PubMed1999

Synthesis and antitumor activity of 7-O-[2,6-dideoxy-2-fluoro-5-C-(trifluoromethyl)-alpha-L-talopyranosyl]- daunomycinone and -adriamycinone.

7-O-[2,6-Dideoxy-2-fluoro-5-C-(trifluoromethyl)-alpha-L-talopyranosyl]- daunomycinone and -adriamycinone have been prepared by the coupling of 3,4-di-O-acetyl-2,6-dideoxy-2-fluoro-5-C-(trifluoromethyl)-alpha-L- talopyranosyl iodide with daunomycinone. The key steps in this synthesis are the regioselective fluorination of methyl alpha-D-lyxopyranoside to give the 4-deoxy-4-fluoro-beta-L-ribopyranoside and the C-trifluoromethylation of the aldehydo-L-ribose derivative to give the 1,1,1-trifluoro-5-monofluoro-L-altritol derivative. Antitumor activities of the synthetic products were compared with those for the 2'-deoxy-2'-fluoro and 2',6'-dideoxy-5'-C-trifluoromethyl analogs.

Animals↗
PubMed1999

Overexpression of thioredoxin in transgenic mice attenuates focal ischemic brain damage.

Thioredoxin (TRX) plays important biological roles both in intra- and extracellular compartments, including in regulation of various intracellular molecules via thiol redox control. We produced TRX overexpressing mice and confirmed that there were no anatomical and physiological differences between wild-type (WT) mice and TRX transgenic (Tg) mice. In the present study we subjected mice to focal brain ischemia to shed light on the role of TRX in brain ischemic injury. At 24 hr after middle cerebral artery occlusion, infarct areas and volume were significantly smaller in Tg mice than in WT mice. Moreover neurological deficit was ameliorated in Tg mice compared with WT mice. Protein carbonyl content, a marker of cellular protein oxidation, in Tg mice showed less increase than did that of WT mice after the ischemic insult. Furthermore, c-fos expression in Tg mice was stronger than in WT mice 1 hr after ischemia. Our results suggest that transgene expression of TRX decreased ischemic neuronal injury and that TRX and the redox state modified by TRX play a crucial role in brain damage during stroke.

Animals↗
PubMed1999

Identification of cis-acting elements in the proximal promoter region for brain-specific exon 1 of the mouse aromatase gene.

Among multiple exons 1 of the mouse aromatase gene, brain-specific exon 1 is only utilized in the hypothalamus and amygdala regions. In this study, identification of the promoter region necessary for basal transcription of the aromatase gene in the brain was undertaken. Deletions of various lengths were introduced into the overall promoter region, which was fused to the chloramphenicol acetyltransferase gene. The resulting reporters were transfected into cultured neurons from the diencephala of fetal mouse brains on embryonic day 13 and then their CAT mRNA levels were determined. The reporter plasmid containing the promoter region 202 bp upstream from the transcriptional initiation site gave the greatest expression. Then binding of trans-acting factors in a nuclear extract of the diencephala to the -202 bp promoter region was investigated by DNase I footprint analysis, multiple protected areas, referred to as Arom-Aalpha, Abeta, Agamma, B and C, being found. Gel shift assays, performed with oligonucleotides corresponding to the protected areas, showed that nuclear DNA binding factors form specific complexes exhibiting different mobilities. Substitution in the Arom-Aalpha or -B sequence in the promoter region in the CAT reporters decreased the CAT mRNA expression levels to about one-fifth the wild type one. These results suggest that multiple nuclear factors bound to the core promoter region participate in the expression of the aromatase gene in mouse brain neurons.

Albumins↗
PubMed1999

Heparan sulfate proteoglycan modulates keratinocyte growth factor signaling through interaction with both ligand and receptor.

Keratinocyte growth factor (KGF) is an unusual fibroblast growth factor (FGF) family member in that its activity is largely restricted to epithelial cells, and added heparin/heparan sulfate inhibits its activity in most cell types. The effects of heparan sulfate proteoglycan (HSPG) on binding and signaling by acidic FGF (aFGF) and KGF via the KGFR were studied using surface-bound and soluble receptor isoforms expressed in wild type and mutant Chinese hamster ovary (CHO) cells lacking HSPG. Low concentrations of added heparin (1 microgram/mL) enhanced the affinity of ligand binding to surface-bound KGFR in CHO mutants, as well as ligand-stimulated MAP kinase activation and c-fos induction, but had little effect on binding or signaling in wild type CHO cells. Higher heparin concentrations inhibited KGF, but not aFGF, binding and signaling. In addition to the known interaction between HSPG and KGF, we found that the KGFR also bound heparin. The biphasic effect of heparin on KGF, but not aFGF, binding and signaling suggests that occupancy of the HSPG binding site on the KGFR may specifically inhibit KGF signaling. In contrast to events on the cell surface, added heparin was not required for high-affinity soluble KGF-KGFR interaction. These results suggest that high-affinity ligand binding is an intrinsic property of the receptor, and that the difference between the HSPG-dependent ligand binding to receptor on cell surfaces and the HSPG-independent binding to soluble receptor may be due to other molecule(s) present on cell surfaces.

Animals↗
PubMed1999

3-Nitropropionic acid induces ischemic tolerance in gerbil hippocampus in vivo.

Systemic administration of high dose of 3-nitropropionic acid (3-NP), an irreversible inhibitor of succinate dehydrogenase, causes neurodegeneration within the striatum in vivo. However, it has been reported that pretreatment with low dose of 3-NP may increase tolerance to subsequent hypoxia in hippocampal slices. The present study investigated whether ischemic tolerance can be induced in gerbil hippocampus in vivo by low dose of 3-NP. After pretreatment with 3-NP (single i.p. injection of 3 mg/kg, body weight 2-4 days prior to forebrain ischemia), the number of surviving neurons in CA1 region of hippocampus against succeeding forebrain ischemia was significantly higher than in the ischemic control group. Our results show that chemical preconditioning with low dose of 3-NP induces ischemic tolerance in gerbil hippocampus in vivo.

Animals↗
PubMed1999

Characterization of ootolith soluble-matrix producing cells in the saccular epithelium of rainbow trout (Oncorhynchus mykiss) inner ear.

Although the organic matrix may play an important role in the growth of teleost otoliths, cellular contributions to the production of the organic matrix have been studied in only a small number of teleost species with limited methods, and are still poorly understood. In order to characterize saccular epithelial cells which produce otolith matrix, antiserum was raised against an EDTA-soluble fraction of otolith matrix (otolith soluble-matrix, OSM) of the rainbow trout. The components in the OSM and in the endolymph were characterized by immunoblotting. The saccular epithelium was immunohistochemically stained with the antiserum and the ultrastructure of OSM immunoreactive cells was studied. By immunoblotting, multiple components (> 94.0 kDa [smeared] and 43.0 kDa) in the OSM reacted with the antiserum, whereas only one band (> 94.0 kDa) was detected in the endolymph. Under immunohistochemical staining, reactions to the antiserum were observed in columnar cells lined at the most peripheral region of the sensory epithelium, transitional epithelial cells, and squamous epithelial cells. Electron microscopic observations revealed that all three types of cells were equipped with extended rough endoplasmic reticulum and prominent Golgi apparatus, suggesting the active production of organic material(s). Dilations of translucent vesicles, apocrine-like extrusions of cytoplasm, and vesicles containing many minute globules were frequently associated with the apical surface of these cells. Some ruptured vesicles were observed, releasing their contents into the endolymphatic space. The present study identified columnar cells lining the most peripheral region of the sensory epithelium, transitional epithelial cells, and squamous epithelial cells as the OSM-producing cells. We suggest that the OSM components are secreted and dissolved into the endolymph and subsequently deposited onto the otolith.

Animals↗
PubMed1999

The importance of total parenteral nutrition-associated tissue zinc distribution in wound healing.

It is well known that zinc (Zn), an essential trace element, plays a role in wound healing. Although the importance of Zn supplementation in total parenteral nutrition (TPN) has been recognized, the difference in tissue Zn distribution induced by TPN and whether this difference influences local wound healing remains uncertain. Thus, we conducted a study using 30 Sprague-Dawley rats to investigate the influence of TPN-induced changes in tissue Zn distribution on wound healing at sites of intestinal anastomosis, muscle, and skin sutures. In the ordinary diet group, no significant differences were observed between subgroups with and without supplemental Zn in tissue Zn distribution or in the healing of intestinal, muscular, and cutaneous wounds. In the subgroup given a low-protein diet without supplemental Zn, a gross change in tissue Zn distribution was noted to occur with a concomitant marked decrease in Zn concentration and the tensile strength of wounded skin. These results indicate an association between wound healing and Zn concentration in the respective tissues in TPN-induced Zn deficiency with alternations in tissue Zn distribution. They also provide evidence of the local action of Zn in wound healing.

Analysis of Variance↗
PubMed1999

A new method for crosstalk correction in simultaneous dual-isotope myocardial imaging with Tl-201 and I-123.

We have developed a new method of crosstalk correction in simultaneous dual-isotope imaging with Tl-201 and I-123 by using crosstalk ratios and a blurring filter. Single isotope myocardial studies (10 for Tl-201 and 7 for I-123) were performed with a dual energy window acquisition mode and two low energy general-purpose collimators. Then two planar images acquired with dual energy windows for a Tl-201 line source and an I-123 line source were obtained to measure line spread functions (LSFs) and crosstalk ratios for each image. The line source experiments showed that the LSFs for the Tl-201 imaging window from the single Tl-201 source were very similar to those for the I-123 imaging window from the single Tl-201 source, but the LSFs for the Tl-201 imaging window from the single I-123 source had broad shapes which differed from those for the I-123 imaging window from the single I-123. To obtain accurate I-123 crosstalk images in the Tl-201 imaging window from the I-123 images in the I-123 imaging window, we designed a low-pass blurring filter. In 7 clinical I-123 MIBG studies, I-123 window images processed with this filter became very similar to the Tl-201 window image from the single I-123 source. The method proposed in this study can accurately correct the crosstalk in dual isotope studies with Tl-201 and I-123 and is easily applicable to conventional gamma camera systems with any dual energy window acquisition mode.

3-Iodobenzylguanidine↗
PubMed1999

Comparison of antiresorptive activities of ipriflavone, an isoflavone derivative, and elcatonin, an eel carbocalcitonin.

Thirty postmenopausal women with reduced bone mineral density were divided randomly into two groups based on the chronological sequence of their first visit to the Osteoporosis Clinic of Katsuragi Hospital. Group I was given 600 mg ipriflavone orally daily and group II was weekly injected intramuscularly with 20 units elcatonin, Asu1-7 eel calcitonin (carbocalcitonin). Lumbar spine BMD was measured by dual-energy X-ray absorptiometry, and trabecular bone mineral density at the distal radius, cortical bone density, and relative cortical volume at the radial diaphysis by peripheral computed tomography before the beginning of the study and at the 4th, 8th, and 12th month. Markers of bone metabolism--serum total alkaline phosphatase, bone-specific alkaline phosphatase, tartrate-resistant acid phosphatase, osteocalcin, intact osteocalcin, PICP and ICTP, and urinary pyridinoline, deoxypyridinoline, and calcium/creatinine (Ca/Cr)--were also measured at the same interval. Plasma parathyroid hormone (PTH) and calcitonin (CT) were measured at the same time. Radial trabecular bone density showed a significantly higher rate of increase in group I (ipriflavone group) than in group II (elcatonin group) at the 4th month, whereas lumbar spine BMD showed more pronounced increase in the elcatonin group than in the ipriflavone group throughout the study period. Bone metabolism markers tended to decline in both groups. Total and intact osteocalcin showed a significant fall from the baseline throughout the study period only in the ipriflavone group. Urine pyridinoline and deoxypyridinoline showed a significant fall from the baseline at the 12th month only in the ipriflavone group. On comparing bone gainers with increase of lumbar spine BMD by 2% or more with bone losers with a decrease by 2% or more, only urine Ca/Cr was significantly different, lower in the former than in the latter, despite the general tendency for bone resorption markers to decrease in bone gainers and to increase in bone losers.

Acid Phosphatase↗
PubMed1999

Affinity profiles of various muscarinic antagonists for cloned human muscarinic acetylcholine receptor (mAChR) subtypes and mAChRs in rat heart and submandibular gland.

A family of five subtypes of muscarinic acetylcholine receptors (mAChR) has been identified based on their molecular structures and second signal transduction pathways. In the present study, we examined the antagonist binding profiles of 9 muscarinic antagonists (atropine, 4-DAMP, pirenzepine, oxybutynin, tiquizium, timepidium, propiverine, darifenacin and zamifenacin) for human muscarinic acetylcholine receptor subtypes (m1, m2, m3, m4 and m5) produced by using a baculovirus infection system in Sf9 insect cells, and rat tissue membrane preparations (heart and submandibular gland). In a scopolamine methyl chloride [N-methyl-3H]- ([3H]NMS) binding assay, pirenzepine and timepidium displayed the highest affinities for the m1 and m2 subtypes, respectively, and both zamifenacin and darifenacin had the highest affinities for the m3 subtype, although the selectivities among the five subtypes were less than 10-fold. Propiverine showed a slightly higher affinity for the m5 subtype, whereas none of the drugs used in this study was uniquely selective for the m4 subtype. The binding affinities of muscarinic antagonists for rat heart and submandibular gland strong correlated with those for human cloned m2 and m3 subtypes, respectively. These data suggest that [3H]NMS binding studies using rat heart and submandibular gland might be useful methods which predict the affinities of test drugs for human muscarinic M2 and M3 receptor subtypes.

Animals↗
PubMed1999

Malignant fibrous histiocytoma of the spermatic cord: a case report.

We present a case of malignant fibrous histiocytoma of the spermatic cord. An 86-year-old man was admitted to the hospital with a right painless scrotal mass. Under the diagnosis of a testicular tumor, right radical orchiectomy was performed. Grossly, the tumor firmly adhered to the spermatic cord. The right testis and epididymis were normal. The histologic diagnosis was malignant fibrous histiocytoma. There was local recurrence 2 months after surgery. The recurrent tumor was resected with the surrounding soft tissue, but the patient died 5 months after the initial operation.

Aged↗
PubMed1999

Sphingosylphosphorylcholine is a potent inducer of intercellular adhesion molecule-1 expression in human keratinocytes.

We recently reported that the epidermis of patients with atopic dermatitis contains an abnormally expressed sphingomyelin deacylase that yields a large amount of sphingosylphosphorylcholine (SPC) rather than ceramide. In this study, we characterize inflammatory roles of newly discovered chemicals in the epidermis by elucidating biologic effects of SPC on intercellular adhesion molecules-1 (ICAM-I) expression by human keratinocytes in culture in comparison with other sphingolipids. Using fluorescence-activated cell sorter analysis, we found that SPC treatment at concentrations of 10-20 microM significantly enhanced the expression of ICAM-I by cultured human keratinocytes in a dose-dependent manner after incubation for 15-24 h, and, using northern blot analysis, that this was accompanied by increased expression of ICAM-1 mRNA within 4 h of incubation. Transforming necrosis factor-alpha (TNF-alpha) levels in the medium of keratinocytes treated at a 10 microM concentration of SPC were significantly increased by 200%. Furthermore, the SPC-induced ICAM-1 expression was partially abolished by the concomitant addition of anti-TNF-alpha, suggesting a partial autocrine involvement of TNF-alpha in ICAM-1 expression. Assay of mitogen-activated protein kinase revealed that 10 microM SPC induced a rapid activation of mitogen-activated protein kinase in human keratinocytes, including an increase in its phosphorylation within 5 min, which then declined to the baseline control level after 30 min. In contrast, sphingomyelin or sphingosine had no significant potential to activate mitogen-activated protein kinase at the same concentration. These findings suggest that SPC plays an important role in the inflammatory process of epidermis in skin diseases, such as atopic dermatitis, with high expression of sphingomyelin deacylase.

Calcium↗
PubMed1999

Intestinal adaptation in pediatric patients with short-bowel syndrome.

The purpose of this study is to evaluate 12 pediatric short-bowel syndrome (SBS) patients experienced at Osaka University Hospital and its affiliated hospitals and to study the intestinal length for achieving intestinal adaptation and the metabolic characteristics. The length of the residual small intestine ranged from 0 to 75 cm with an average of 47 cm and an ileocecal valve had been resected in five cases. Total parenteral nutrition (TPN) was started immediately after operation and was gradually substituted by enteral nutrition. No patient died during the follow-up period. Eight of 12 patients could be weaned from TPN with residual intestinal length of 27 to 75 cm (mean 57 cm). Four patients with the residual intestine of 0 to 45 cm (mean 22 cm) were unable to achieve intestinal adaptation. The rate of catheter-related sepsis per 1000 catheter days was 0.63. Fatty liver was detected in two cases, but no patient developed progressive liver failure. Plasma arginine and citrulline were decreased in patients who were unable to achieve intestinal adaptation. Our nutritional support program provided excellent survival for pediatric SBS patients primarily due to the low incidence of catheter-related sepsis and no episode of severe liver disease. Patients with more than 16 cm of residual intestinal length can be expected to be weaned from TPN.

Adaptation, Physiological↗
PubMed1999

Redox control of Epstein-Barr virus replication by human thioredoxin/ATL-derived factor: differential regulation of lytic and latent infection.

Human thioredoxin (hTRX)/adult T-cell leukemia (ATL)-derived factor (ADF) was originally reported as an interleukin-2 (IL-2) receptor-alpha-inducing factor produced by human T-cell lymphotropic virus-1-positive (HTLV-1+) cell lines. Growing evidence indicates that hTRX/ADF plays important roles in cellular responses against oxidative stress and is involved in a variety of cellular functions. A high level of hTRX/ADF expression is also observed in other human virus-infected cell lines including those of Epstein-Barr virus (EBV) and human papillomavirus. In this report, we analyzed the effect of hTRX/ADF on lytic amplification and persistent replication of EBV as a model for lytic versus latent phase of viral replication in host cells. Addition of hTRX/ADF clearly suppressed lytic replication of EBV in Raji cells and B95-8 cells induced to the lytic phase of 12-O-tetradecanoylphorbol-13-acetate (TPA), and it prevented the death of these cells evoked by the lytic induction. In contrast, hTRX/ADF did not have any effect on persistent replication in the latent phase. These data indicated that hTRX/ADF prevents EBV-transformed cells from proceeding into the lytic phase and regulates cohabitation of EBV and its host cells.

Carcinogens↗
PubMed1999

Nitric oxide synthase inhibitor attenuates intestinal damage induced by zinc deficiency in rats.

A nitric oxide synthase (NOS) inhibitor, NG-nitro-L -arginine methyl ester (L-NAME), was given to zinc-deficient (ZD) rats to determine whether it prevents the intestinal damage usually observed under these conditions. Weanling male rats were given free access to a ZD diet (2 mg zinc/kg), whereas control rats including pair-fed (PF) and ad libitum consumption (AL) groups were given a zinc-supplemented (50.8 mg zinc/kg) diet for 4 wk. Half of the ZD rats received L-NAME (0.3 g/L in drinking water) for 3 wk starting at the wk 2 of the deficient period. Plasma zinc concentration in ZD rats was significantly lower (P < 0.05) than that of AL and PF rats. Administration of L-NAME did not alter this concentration. Intestinal zinc concentration did not differ among groups. However, metallothionein-1 (MT-1) mRNA level was significantly lower in the intestine of ZD rats than in AL or PF rats. Treatment of ZD rats with L-NAME did not affect this level. Intestinal microvascular permeability evaluated by Evans blue showed significantly higher extravasation in ZD rats than in AL rats, whereas L-NAME administration inhibited the extravasation. Expression of inducible NOS mRNA was observed in intestine of ZD but not of AL or PF rats, and there was no significant difference between ZD rats, regardless of L-NAME treatment. The activity ratio of inducible NOS to total NOS in ZD rats not receiving L-NAME was significantly higher than that in AL rats or ZD rats treated with L-NAME (P < 0.05). The number of apoptotic-positive and goblet cells in intestinal villi was significantly higher in ZD rats compared with AL or PF rats. L-NAME administration in ZD rats reversed this effect. These results indicate that inhibition of NOS ameliorates zinc deficiency-induced intestinal damage in rats.

Animals↗