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Biomedical subjects

I Tanaka

Publications and source records attributed to I Tanaka.

At least 145 records · Page 8Linked to original sources
PubMed1998

Differential regulation of mouse uncoupling proteins among brown adipose tissue, white adipose tissue, and skeletal muscle in chronic beta 3 adrenergic receptor agonist treatment.

Uncoupling proteins (UCPs) are inner mitochondrial membrane transporters that dissipate the proton gradient, releasing stored energy as heat, without coupling to other energy-consuming processes. Therefore, the UCPs are thought to be important determinants of the metabolic efficiency. To elucidate relationships between the UCPs expressions and insulin sensitivity improvement, we treated KK-Ay mice with beta 3 adrenergic receptor agonist for 21 days and examined the changes of the UCPs mRNA expressions in various tissues. Chronic treatment of a specific beta 3 adrenergic receptor agonist, CL316,243 (0.2 mg/kg body weight/day s.c.) markedly increased the expressions of uncoupling protein 1 (UCP1), uncoupling protein 2 (UCP2), and uncoupling protein 3 (UCP3) by 14-fold, 6-fold, and 16-fold, respectively, in the brown adipose tissue (BAT). The UCP1 and UCP3 mRNA expressions in the white adipose tissue (WAT) were also increased by 12-fold and 9-fold, respectively, but the UCP2 mRNA expression was not changed in this tissue. Interestingly, the UCP2 and UCP3 mRNA expressions were strikingly decreased in the skeletal muscle and heart. Particularly, the UCP3 mRNA expression level in the skeletal muscle was dropped to 10% of that of the saline-treated control mice, indicating that the UCPs mRNA expressions are regulated in tissue-specific ways. The concentrations of plasma insulin and circulating free fatty acid (FFA) were significantly decreased, suggesting that they correlate with the reductions of the UCP2 and UCP3 mRNA expressions in the skeletal muscle and heart. It has been thought that the UCP1 and UCP3 mRNA expressions in the BAT and WAT are mainly controlled by the hypothalamus via the sympathetic nervous system, while the levels of insulin, FFA or both may play important roles in the control of the UCP2 and UCP3 mRNA expressions in the skeletal muscle an heart.

Adipose Tissue↗
PubMed1998

Crystallization and preliminary X-ray crystallographic study of a 23S rRNA binding domain of the ribosomal protein L2 from Bacillus stearothermophilus.

Ribosomal protein L2 from Bacillus stearothermophilus, a single polypeptide chain with 275 amino acid residues, is a primary 23S rRNA-binding protein in the large ribosomal subunit. Crystals of a 23S rRNA binding domain (BstL2-RBD: positions 60-201) of the ribosomal protein L2 from B. stearothermophilus overexpressed in Escherichia coli have been grown in 0.1 M MES (pH 6.5) containing 15% polyethylene glycol 20 000. The crystals diffract to 2.3-A resolution on a synchrotron X-ray source. The crystal belongs to the space group P1 and the unit cell axes are a = 28.05, b = 36.20, c = 69.74 A, alpha = 99.58 degrees, beta = 95.86 degrees, and gamma = 102.62 degrees. There are two molecules of the BstL2-RBD in the asymmetric unit.

Bacterial Proteins↗
PubMed1998

Metalloproteinase-like, disintegrin-like, cysteine-rich proteins MDC2 and MDC3: novel human cellular disintegrins highly expressed in the brain.

Cellular disintegrins are a family of membrane-anchored proteins structurally related to snake venom disintegrins, and are potential regulators of cell-cell and cell-matrix interactions. The members of this protein family are also called ADAMs (a disintegrin and metalloproteinase) or MDC proteins (metalloproteinase-like disintegrin-like cysteine-rich), because they all contain disintegrin-like and metalloproteinase-like domains. In this paper, we report the cloning and sequence analysis of two novel additional members of this family, which we have termed MDC2 and MDC3. The deduced amino acid sequences reveal that the two proteins possess typical cellular disintegrin structures [that is, pro-, metalloproteinase-like, disintegrin-like, cysteine-rich, epidermal growth factor-like, transmembrane, and cytoplasmic domains] and exhibit high sequence similarity with human MDC/ADAM11 protein [Katagiri, Harada, Emi and Nakamura (1995) Cytogenet. Cell Genet. 68, 39-44]. A zinc-binding motif, which is critical for proteinase activity, is disrupted in the metalloproteinase-like domain of MDC2 and MDC3, as well as MDC/ADAM11. In the disintegrin-like domain of snake venom short disintegrins, the RDG-containing loops are critical for integrin binding. These three MDCs do not contain the RDG sequences, but the corresponding loops in these proteins are similar to each other. Northern blot analysis revealed that the mRNAs of MDC2, MDC3 and MDC/ADAM11 are highly expressed in the brain. These findings suggest that these proteins may function as integrin ligands in the brain.

ADAM Proteins↗
PubMed1998

Cloning of mouse uncoupling protein 3 cDNA and 5'-flanking region, and its genetic map.

Brown adipose tissue and skeletal muscle are important sites of non-shivering thermogenesis. It has been known that UCP1 and UCP2 function as the main effector of the thermogenesis: the former is expressed exclusively in brown adipose tissue, whereas the latter is distributed widely. Recently, the third UCP homologue was discovered in humans, which was designated as UCP3. We now report molecular cloning of full-length mouse UCP3 cDNA and its 5'-flanking genomic region. The mouse UCP3 cDNA sequence predicted a 308-amino acid protein, and the overall identity between the mouse and human UCP3 proteins was 85.6%. The mouse UCP3 amino acid sequence was 54.7% and 73.1% identical to the mouse UCP1 and UCP2, respectively. Expression of the mouse UCP3 was found to be abundant in skeletal muscle and somewhat less abundant in heart, but was minimally expressed in other critical organs. The sequences of 5'-flanking regions of the mouse UCP1 and UCP3 were very different, resulting in different distributions of putative transcriptional factor binding sites. The differences could reflect tissue-specific expression of the UCPs. The mouse Ucp3 gene was mapped near Ucp2 on chromosome 7, suggesting that the Ucp2 and Ucp3 are clustered genes. This region is boundary of synteny between human chromosome 11q13 and 11p15. As Solanes et al. reported that both human UCP2 and UCP3 genes are assigned to chromosome 11q13, the region where the mouse Ucp2 and Ucp3 are localized is syntenic to human chromosome 11q13.

Amino Acid Sequence↗
PubMed1998

Cloning of 5'-flanking region and a polymorphic CTT trinucleotide repeat within 5'-untranslated region of mouse R-type calcium channel alpha1-subunit (Cchra1) gene, and its genetic mapping.

The 5'-flanking region of the mouse R-type calcium channel (Cchra1) gene was cloned, and a transcriptional start point (tsp) was determined by rapid amplification of 5'-cDNA end (5'RACE) method. The putative promoter region of the gene contained no obvious TATA or CCAAT element in the expected positions, but multiple putative binding sites for transcriptional factors, such as Sp1, AP-1, AP-2, AP-3, EGR-1, EGR-2, NF-kappaB and HIP1, were detected. We found the existence of a tandem CTT trinucleotide repeat within the 5'-untranslated region (UTR) of the gene, and its polymorphism between C57BL/6J and Mus spretus. Using this polymorphism, the Cchra1 was mapped to the region of chromosome 1 where the synteny to human chromosome 1q was conserved.

Amino Acid Sequence↗
PubMed1998

Activity of rat pump neurons is modulated with central respiratory rhythm.

The firing properties of the second-order neurons of the slowly-adapting pulmonary stretch receptors called pump neurons (P-cells), were studied in Nembutal-anesthetized, paralyzed, and artificially-ventilated rats. Extracellular recording was made from single P-cells which were monosynaptically activated by electrical stimulation of the vagal afferents and fired in phase with lung inflations. In the majority of the P-cells examined (49/52), the firing was suppressed to various extents in the inspiratory phase: in effect, their firing was accentuated at the time of the inspiratory off-switch. This issue has never been reported in cat P-cells, on which relatively rich data have been accumulated. The present results suggest that rat P-cells do not only relay information from the lung stretch receptors but also integrate the central respiratory inputs.

Afferent Pathways↗
PubMed1998

The role of platelet von Willebrand factor in the binding of factor VIII to activated platelets.

Factor VIII binds to activated platelets and contributes to the tenase complex assembled on the platelet membrane surface. We have examined the role of platelet von Willebrand factor in the binding of factor VIII to platelets using a platelet captured enzyme-linked immunosorbent assay. Purified factor VIII bound to activated normal platelets in a dose dependent manner. Factor VIII also bound to platelets obtained from a patient with Type 2N von Willebrand disease, although in this case the binding was reduced to approximately 50% of that seen with control platelets. Furthermore, factor VIII bound to Type 3 von Willebrand disease platelets in the absence of detectable von Willebrand factor. In this instance the binding reaction appeared to be approximately 30% of that seen with the same number of normal platelets. An anti-A3 domain monoclonal antibody, NMC-VIII/10, which recognizes the amino-terminal acidic region of the factor VIII light chain, and an anti-C2 domain monoclonal antibody, NMC-VIII/5, which also moderates the binding of factor VIII to phosphatidylserine, inhibited the association between factor VIII and platelets. Inhibition was more remarkable with NMC-VIII/5 than with NMC-VIII/ 10 but not complete. The findings suggest that the binding of factor VIII to activated platelets is not based on a single ligand-receptor relationship, although a predominant role exists for the platelet von Willebrand factor. Furthermore, both the amino-terminal acidic region of the A3 domain and the C2 domain participate in the binding of factor VIII to activated platelets.

Binding Sites↗
PubMed1998

Pontine projections of pulmonary slowly adapting receptor relay neurons in the cat.

Pontine projections of second-order neurons activated by vagal afferents originating from pulmonary slowly adapting receptors were studied electrophysiologically in Nembutal-anesthetized, paralyzed and artificially ventilated cats. Extracellular recordings from these neurons (referred to as P-cells) were made in the nucleus tractus solitarii. Antidromic mapping of the brain stem showed that many P-cells examined projected their axons to the ipsilateral pons as well as the medulla. Axonal arborizations were found in the parabrachial nucleus, i.e. in the area corresponding to the pontine respiratory group. In some P-cells, axonal arborizations were also found in the A5 area. The present results suggest that the P-cells are involved in pontine pneumotaxic mechanisms.

Adaptation, Physiological↗
PubMed1998

Molecular cloning of human D-dopachrome tautomerase cDNA: N-terminal proline is essential for enzyme activation.

D-Dopachrome tautomerase converts 2-carboxy-2,3-dihydroindole-5,6-quinone (D-dopachrome) into 5,6-dihydroxyindole. This protein has an amino acid sequence that is highly homologous with that of macrophage migration inhibitory factor (MIF), which has the potential to catalyze D-dopachrome to 5,6-dihydroxyindole-2-carboxylic acid and is an important cytokine for T-lymphocyte activation. We isolated and sequenced a 566 bp-long cDNA encoding human D-dopachrome tautomerase. The cDNA contains an open reading frame encoding 118 amino acids, including the initiator methionine. The amino acid sequence of the protein shares 80% homology with that of the rat enzyme. Northern blot analysis demonstrated that mRNA of D-dopachrome tautomerase is expressed in a large amount in the liver, and to lesser extent in other organs, including the heart, lung and pancreas. After purification of D-dopachrome tautomerase expressed in E. coli, we confirmed that the recombinant protein catalyzes the conversion of D-dopachrome to 5,6-dihydroxyindole. Its catalytic mechanism is not well understood. We found that the protein completely lost the enzyme activity when the N-terminal proline residue was replaced with alanine by site-directed mutagenesis. This fact suggests that the N-terminal proline is essential for the catalytic mechanism. Although the precise pathophysiological function of D-dopachrome tautomerase remains to be elucidated, the present results could contribute to further understanding of isomerase activity in relation to the immune response.

Amino Acid Sequence↗
PubMed1998

Inhibition of NF-kappa B transcriptional activity by alpha-tocopheryl succinate.

The role of vitamin E in cell regulation in addition to its function as an antioxidant has attracted attention. The effects of alpha-tocopherol (T) and alpha-tocopheryl succinate (TS) on transcriptional activation of the tumor necrosis factor alpha (TNF-alpha) gene and nuclear factor kappa B (NF-kappa B) activation were examined. Two stable transformants were used: TR-1 cells derived from THP-1 cells transfected with a vector contains the human TNF-alpha promoter (1.4-kb) joined to the human placental alkaline phosphatase (PLAP) coding sequence, and B164 cells derived from the same cell line but carrying the vector containing the human beta-actin promoter (4.3-kb) as a control. The transfectants were cultured in the presence of TS, followed by stimulation with lipopolysaccharide (LPS). After stimulation, PLAP activity secreted into the culture medium was measured. TS reduced TNF-alpha transcriptional activity in a concentration-dependent manner, while no effect was observed on that of the beta-actin promoter. Gel shift assay revealed that THP-1 cells pretreated with TS and then with LPS showed inhibition of NF-kappa B activity by 43% at 50 microM versus the TS-untreated group. Since TS did not affect activator protein-1 (AP-1) activity under the same conditions, the inhibitory effect of TS on NF-kappa B activation might be specific. However, T had no effect on the results of the gel shift assay. Vitamin E transportation was analyzed by simultaneous determination of vitamin E and its derivatives using HPLC. The vitamin E recovered from culture pellets showed almost the same amounts of T and TS transferred and was recovered in unchanged form. These observations indicated that TS inhibited NF-kappa B activation and/or translocation to the nuclei in its unchanged form under the culture conditions used here. These results suggested that vitamin E is involved in signal transduction via an effect distinct from its antioxidant function. To explain the lack of activity with T, it remains to be clarified whether physiological incorporation of T occurred.

Actins↗
PubMed1998

Social diffusion of modified louse egg-handling techniques during grooming in free-ranging Japanese macaques.

Changes in louse egg-handling techniques during grooming were studied among a free-ranging troop of Japanese macaques, Macaca fuscata, from 1990 to 1997 at Jigokudani Monkey Park, the Shiga Heights, Nagano prefecture, Japan, where the skills were distributed based on matrilineages. One female altered her louse egg-handling technique from a one-hair combing technique, in which macaques comb a single hair with an egg without first loosening the cement of the egg, to a forefinger nail loosening technique, in which macaques use the nail of the forefinger to loosen an egg before combing. Therefore, louse egg-handling skills were not fixed, but could change. This female's new technique was later adopted by her sister, daughters and granddaughter. Not all elements of the technique were acquired at the same time, however, and individuals varied in when they acquired them. These shifts suggest that the mechanism of acquiring louse egg-handling techniques is information transfer of the partial functions and partial structure of the techniques together with individual learning. One female's initial technique (skin pinching), against which groomees reacted, was replaced by the forefinger nail loosening technique even though the techniques, once mastered, were equally efficient and the new technique was initially less efficient. The social interaction between grooming partners may thus impede the diffusion of the harmful behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1998

Effect of the lipid peroxide reaction caused by repeated cold stress on cisplatin-induced nephrotoxicity.

The peroxide reaction in mouse kidney was examined in order to determine the relationship between the lipid peroxide reaction caused by SART (specific alternation of rhythm in temperature) stress and that caused by drug administration. After exerting SART stress for one wk on 6-wk-old male ddY mice (stress group), the peroxide reaction generated by the administration of a single dose of cis-diamminedichloroplatinum (cisplatin: CDDP, 10 mg/kg, i.p.) into SART-stressed mice (stress + CDDP group) was compared with the reaction of CDDP-administered nonstressed mice (CDDP group), saline-administered nonstressed mice (saline group), and saline-administered SART-stressed mice (stress + saline group). Lipid peroxidation in the kidneys was significantly higher in the stress group upon cessation of stress exertion than in the normal group. However, no significant difference in the lipid peroxide level after administration of CDDP was observed between the CDDP groups. The renal glutathione levels were significantly different between the CDDP groups and the saline administered groups. These results indicate that the peroxide reaction is generated in the kidneys by stress, but stress has no effect on the peroxide damage caused by CDDP administration. However, the contribution of stress to renal function impairment requires further evaluation.

Animals↗
PubMed1998

[Spontaneous esophageal rupture after gastrointestinal examination using barium].

We experienced a case of spontaneous rupture of the esophagus after gastrointestinal examination using barium. A 48-year-old male experienced severe chest pain after vomiting following gastrointestinal examination. Chest X-ray revealed a right pneumothorax and pleural effusion by barium. We diagnosed spontaneous rupture of the esophagus and performed right thoracotomy 6 hours after onset of symptoms. At 10 cm above the diaphragm, there was a vertical perforation 3 cm in length. Following saline lavage, the ruptured esophageal wall was directly closed by the layer to layer method. The post operative course was uneventful and the patient was discharged 3 weeks after surgery. Cases of spontaneous rupture of the esophagus into the right thoracic cavity induced by gastrointestinal examination are extremely rare.

Barium Sulfate↗
PubMed1998

Prostaglandin E2 (PGE2) autoamplifies its production through EP1 subtype of PGE receptor in mouse osteoblastic MC3T3-E1 cells.

Prostaglandin E2 (PGE2) is known to autoamplify its production in the osteoblasts through the induction of prostaglandin G/H synthase-2 (PGHS-2), which is the inducible form of the rate-limiting enzyme in PG synthesis, PGHS. To elucidate the cellular mechanism mediating this process, we have employed the PGE2 analogs, which are specific agonists for four subtypes of PGE receptor, and studied the potency of these analogs to induce PGHS-2 mRNA in mouse osteoblastic MC3T3-E1 cells. The induction was mainly observed by 17-phenyl-omega-trinor PGE2 (EP1 agonist) and sulprostone (EP3/EP1 agonist), but not by butaprost (EP2 agonist) or 11-deoxy PGE1 (EP4/EP2 agonist). Since EP3 subtype was undetectable in MC3T3-E1 cells, these data indicate that PGHS-2 mRNA induction is mediated through EP1 subtype of PGE receptor in MC3T3-E1 cells. PGE2 production determined by radioimmunoassay was also increased by 17-phenyl-omega-trinor PGE2 and sulprostone. The autoamplification of PGE2 production is considered to be important in elongating the otherwise short-lived PGE2 action in certain physiological conditions such as mechanical stress and fracture healing, as well as the pathological inflammatory bone loss. The observations in the present study provide us with the better understanding of these processes.

3T3 Cells↗
PubMed1998

Matching the crystallographic structure of ribosomal protein S7 to a three-dimensional model of the 16S ribosomal RNA.

Two recently published but independently derived structures, namely the X-ray crystallographic structure of ribosomal protein S7 and the "binding pocket" for this protein in a three-dimensional model of the 16S rRNA, have been correlated with one another. The known rRNA-protein interactions for S7 include a minimum binding site, a number of footprint sites, and two RNA-protein crosslink sites on the 16S rRNA, all of which form a compact group in the published 16S rRNA model (despite the fact that these interactions were not used as primary modeling constraints in building that model). The amino acids in protein S7 that are involved in the two crosslinks to 16S rRNA have also been determined in previous studies, and here we have used these sites to orient the crystallographic structure of S7 relative to its rRNA binding pocket. Some minor alterations were made to the rRNA model to improve the fit. In the resulting structure, the principal positively charged surface of the protein is in contact with the 16S rRNA, and all of the RNA-protein interaction data are satisfied. The quality of the fit gives added confidence as to the validity of the 16S rRNA model. Protein S7 is furthermore known to be crosslinked both to P site-bound tRNA and to mRNA at positions upstream of the P site codon; the matched S7-16S rRNA structure makes a prediction as to the location of this crosslink site within the protein molecule.

Anticodon↗