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T Takabatake

Publications and source records attributed to T Takabatake.

At least 19 recordsLinked to original sources
PubMed2000

Distribution of dorsal-forming activity in precleavage embryos of the Japanese newt, Cynops pyrrhogaster: effects of deletion of vegetal cytoplasm, UV irradiation, and lithium treatment.

Two types of axis-deficient embryos developed after deletion of the vegetal cytoplasm: wasp-shaped embryos and permanent-blastula-type embryos. In situ hybridization revealed that neither type of axis-deficient embryo expressed goosecoid or pax-6. brachyury was expressed in the constricted waist region of the wasp-shaped embryos but was not expressed in the permanent-blastula-type embryos. Further, we examined the effect of UV irradiation on Japanese newt embryos. Surprisingly, UV-irradiated Japanese newt eggs formed hyperdorsalized embryos. These embryos gastrulated in an irregular circular fashion with goosecoid expression in the circular equatorial region. At tailbud stage, these embryos formed a proboscis which is very reminiscent of that formed in hyperdorsalized Xenopus embryos. Transplantation of the marginal region of the UV-irradiated embryos revealed that the entire marginal zone had organizer activity. Thus we conclude that UV hyperdorsalizes Japanese newt embryos. Finally, lithium treatment of normal embryos at the 32-cell stage also resulted in hyperdorsalization. Lithium treatment of vegetally deleted embryos had two distinct results. Lithium treatment of permanent-blastula-type embryos did not result in the formation of dorsal axial structures, while the same treatment reinduced gastrulation and dorsal axis formation in the wasp-shaped embryos. Based on these results, we propose a model for early axis specification in Japanese newt embryos. The model presented here is fundamentally identical to the Xenopus model, with some important modifications. The vegetally located determinants required for dorsal development (dorsal determinants, DDs) are distributed over a wider region at fertilization in Japanese newt embryos than in Xenopus embryos. The marginal region of the Japanese newt embryo at the beginning of development overlaps with the field of the DDs. Gastrulation is very likely to be a dorsal marginal-specific property, while self-constriction is most probably a ventral marginal-specific property in Japanese newt embryos.

Animals↗
PubMed2000

Conserved and divergent expression of T-box genes Tbx2-Tbx5 in Xenopus.

We report here the identification of four members of T-box family genes, Xltbx2-Xltbx5, in Xenopus. Two of them are probable pseudovariant genes of XTbx5 and ET, a putative Xenopus ortholog of Tbx3. We compared their expression patterns in both embryos and limbs. In embryos, expression of Xltbx2 and Xltbx3 showed novel diversities, such as Xltbx2 in the neural crest cells and Xltbx3 in the ventral spinal cord, together with mutual similarities in the following regions: dorsal retina, proctoderm, lateral line organ, cement gland and cranial ganglia. The patterns in limbs were highly conserved with mouse and chick orthologs, including the limb-type specific expression of Xltbx4 and Xltbx5. In addition, RT-PCR analysis showed that they are expressed weakly even in adult limbs as previously reported in the newt.

Amino Acid Sequence↗
PubMed1999

The early expression control of Xepsin by nonaxial and planar posteriorizing signals in Xenopus epidermis.

The control mechanism of the anteroposterior axis specification in Xenopus epidermis was studied by comparing the expression of a novel anterior marker, Xepsin, with that of a panepidermal marker, type I keratin. Xepsin mRNA, which encodes a novel Xenopus serine protease, is transcribed zygotically with the expression peak in neurula stages. In normal development, its expression is limited to the anterior and anterior-dorsal portions within epidermis during neurula and tailbud stages, respectively. In UV-irradiated ventralized embryos (dorsoanterior index, DAI 0 and 1), an expression boundary for Xepsin is apparently formed within the epidermis. In contrast, Xepsin expression was observed throughout the epidermis in LiCl-treated dorsalized embryos (DAI 10), as seen from an expression pattern indistinguishable from that of type I keratin. These data suggest that posteriorizing signals which suppress the transcription of Xepsin are present in nonaxial regions and absent in the anterior dorsal mesoderm. That posteriorizing signals were present in nonaxial regions was also supported by a conjugation experiment in which Xepsin expression was suppressed in ectodermal explants conjugated with lateral or ventral marginal zone. Moreover, the partly suppressed expression of Xepsin in the epidermal region of exogastrulae indicates that the signals may travel horizontally within the plane of the epidermis. We also present data showing that both treatment with retinoic acid and the overexpression of a constitutively active form of a retinoic acid receptor caused the suppression of Xepsin mRNA transcription, suggesting that anterior-posterior patterning in the central nervous system and in the epidermis may share common endogenous factors, i.e. , retinoids, in the Xenopus embryo.

Amino Acid Sequence↗
PubMed1999

Expression and secretion of a biologically active mouse sonic hedgehog protein by the methylotrophic yeast Pichia pastoris.

We have successfully secreted the amino-terminal functional domain of mouse sonic hedgehog protein (SHH) into culture fluid using a yeast Pichia pastoris expression system. A cDNA fragment encoding the amino-terminal domain of mouse SHH was inserted downstream of the Saccharomyces cerevisiae alpha-mating factor secretion signal. The DNA fragment was introduced into the host genome by the spheroplast transformation method. Transformants were selected based on their resistance to G418: His+ transformants which showed resistance to over 8 mg G418/ml were selected and analyzed for determination of the plasmid copy number. One His+ clone which has eight copies of the expression cassette per genome was cultured in minimal medium deficient for histidine, and further cultured in buffered medium supplemented with methanol which activates the AOX1 promoter. SDS-PAGE analysis indicated efficient expression and secretion of mouse SHH into culture fluid. The yield of secreted SHH was estimated to be 50 micrograms/ml. Purified protein was assayed for biological activity and found to activate the transcription of the Patched genes (Ptc-1 and Ptc-2) encoding receptors for SHH.

Animals↗
PubMed1999

Renal effects of efonidipine hydrochloride, a new calcium antagonist, in spontaneously hypertensive rats with glomerular injury.

1. To obtain some insight into the renoprotective mechanism of the new calcium antagonist efonidipine hydrochloride, we evaluated the acute effects of efonidipine on proteinuria, glomerular haemodynamics and the tubuloglomerular feedback (TGF) mechanism in anaesthetized 24-25-week-old spontaneously hypertensive rats (SHR) with glomerular injury. 2. Efonidipine infusion at 10 micrograms/kg per h following a bolus dose of 10 micrograms/kg, i.v., reduced systemic blood pressure (BP) and renal vascular resistance, whereas renal plasma flow (RPF), glomerular filtration rate (GFR), filtration fraction, urine volume and urinary sodium excretion were unaltered. Urinary protein excretion was clearly diminished from 163 +/- 25 to 105 +/- 24 ng/min per g kidney weight. 3. Micropuncture experiments revealed that the maximal reduction of proximal stop-flow pressure (SFP), an index of glomerular capillary pressure (Pgc), induced by loop of Henle perfusion was significantly less with efonidipine treatment (6.7 +/- 1.0% of SFP with no loop flow) than in control (23.8 +/- 3.1%). In the presence of efonidipine, SFP at half-maximal reduction (SFP1/2max), which approximates Pgc at the in vivo steady state tubular flow rate, remained unchanged compared with control (36.9 +/- 0.8 vs 35.3 +/- 0.7 mmHg, respectively) and the slope of dependency on mean BP was not different between control and efonidipine. 4. These results indicate that efonidipine attenuates the TGF response in SHR by dilating the afferent arteriole, thus maintaining the level of RPF and GFR despite reduced renal perfusion pressure. Constant GFR and SFP1/2max under efonidipine suggest that single nephron GFR and Pgc remain unaltered and that a marked reduction in proteinuria is achieved without changes in single nephron GFR or Pgc of superficial nephrons.

Animals↗
PubMed1999

Expression of five novel T-box genes and brachyury during embryogenesis, and in developing and regenerating limbs and tails of newts.

Several T-box genes are considered to play important roles in developing limbs, tails and neural retinae. Five novel T-box genes in the Japanese newt were isolated and their expression was analyzed, together with another T-box gene of brachyury, during embryogenesis and in the developing and regenerating limbs and tail. Four are designated CpTbx2, CpTbx3, CpTbx6R and CpEomesodermin based on molecular phylogenetic analyses, and the other is named CpUbiqT from its ubiquitous expression. While all were expressed during embryogenesis, only four of them (CpTbx2, CpTbx3, CpUbiqT and brachyury) were detected in developing limbs and/or tails. Except for brachyury, they were continuously expressed in normal adult appendages and showed elevated expression levels in regenerating limbs, whereas only CpTbx2 showed significant up-regulation in regenerating tails. Compared with orthologous genes in other species, CpTbx2, CpTbx3 and CpEomesodermin showed several notable differences such as an abundance of maternal transcripts of CpEomesodermin, a unique insertion sequence within the T-box domain of CpTbx2, and a lack of visible expression of CpTbx2and CpTbx3 in the apical ectodermal region of developing limbs. In view of the uniqueness of the newt, these results are discussed with respect to the possibility of their involvement in regeneration.

Amino Acid Sequence↗
PubMed1999

A calcium antagonist protects against doxorubicin-induced impairment of calcium handling in neonatal rat cardiac myocytes.

The effects of doxorubicin (DOX) on intracellular calcium transients and the cardioprotective effects of a calcium antagonist on DOX-induced impairment of calcium handling were examined in neonatal rat cultured cardiac myocytes. Cultured cardiac myocytes isolated from neonatal Wistar-Kyoto rats were treated with DOX for 24 h. Field-stimulated calcium transients in single myocytes were measured in the presence or absence of isoproterenol using fura-2/AM. Calcium transients were also measured after the addition of DOX to myocytes pretreated with a calcium antagonist, benidipine. DOX reduced the amplitude, maximum velocity of increase and decrease of calcium transients and prolonged the time course of calcium transients and impaired the beta-adrenoceptor responsiveness of calcium transients in a concentration-dependent manner. The DOX-induced impairment of calcium transients and beta-adrenoceptor responsiveness was improved by 10(-8) mol/L of benidipine. However, these improvements decreased with increasing concentrations of benidipine. DOX impaired both the mobilization and removal of intracellular calcium ions in contraction-relaxation cycles and the response of calcium transients to beta-adrenoceptor stimulation. Appropriate concentration of benidipine ameliorated DOX-induced impairment of calcium dynamics, suggesting that benidipine, a long-acting calcium antagonist, has potential clinical usefulness on DOX-induced abnormal calcium handling.

Animals↗
PubMed1998

Overlapping and non-overlapping Ptch2 expression with Shh during mouse embryogenesis.

In Drosophila, patched encodes a negative regulator of Hedgehog signaling. Biochemical experiments have demonstrated that vertebrate patched homologues might function as a Sonic hedgehog (Shh) receptor. In mice, two patched homologues, Ptch and Ptch2, have been identified. Sequence comparison have suggested that they might possess distinct properties in Shh signaling. In the developing tooth, hair and whisker, Shh and Ptch2 are co-expressed in the epithelium while Ptch is strongly expressed in the mesenchymal cells. We report here the chromosomal localization of Ptch2 and further analysis of Ptch2 expression. Throughout mouse development, the level of Ptch2 expression is significantly lower than that of Ptch. In early mouse embryos, Ptch and Ptch2 were found to be co-expressed in regions adjacent to Shh-expressing cells in the developing CNS. Similar to other epidermal structures, Shh and Ptch2 also show overlapping expression in the developing nasal gland and eyelids. Thus, during mouse development, Ptch2 is expressed in both Shh-producing and -nonproducing cells.

Animals↗
PubMed1998

Isolation and characterization of a gene expressed mainly in the gastric epithelium, a novel member of the ep37 family that belongs to the betagamma-crystallin superfamily.

EP37 family proteins are non-lens members of the betagamma-crystallin superfamily, of which expression is observed in integumental tissues of the Japanese newt, Cynops pyrrhogaster. In the present study, a gene was isolated that has high homology with ep37 and is transcribed mainly in the gastric epithelial cells and hence designated gep. The predicted amino acid sequence of the gep cDNA contains four betagamma-crystallin motifs in the N-terminal half, as is the case in the integumental EP37 proteins. Immunohistochemical analysis showed that GEP protein was mainly localized on the luminal content of the surface mucous cells of the gastric epithelium in both premetamorphic larvae and adults. In addition, GEP protein was also expressed in fundic glands after metamorphosis. Considering the fact that beta- and gamma-crystallins are evolutionarily related to stress-induced proteins, this localization suggests that GEP protein may have an evolutionarily conserved role in protection against physico-chemical stresses, such as physical abrasion and autodigestion, during assimilation.

Amino Acid Sequence↗
PubMed1998

Control of rat glomerular microcirculation by juxtaglomerular adenosine A1 receptors.

The role of adenosine A1 receptors in the glomerular microcirculation and tubuloglomerular feedback (TGF) was studied in anesthetized Sprague-Dawley rats. TGF activity was assessed as the reduction in proximal tubular stop-flow pressure (SFP) on establishing orthograde perfusion of the loop of Henle with artificial tubular fluid at 40 nl/min. Administration of a selective A1 receptor antagonist, KW-3902 (0.5 microg/kg/min i.v.), increased fractional excretion of Na (FE(Na)) 4.3-fold without changing blood pressure, glomerular filtration rate, renal plasma flow, or filtration fraction. SFP in the absence of distal flow (SFP0) increased, and TGF-mediated SFP reduction was suppressed dose dependently [by 23 +/- 2% from an SFP0 of 34 +/- 1 mm Hg, by 15 +/- 4% from 36 +/- 2 mm Hg, and by 2 +/- 1% from 39 +/- 1 mm Hg during vehicle, low- and high-dose infusions (0.5 and 5.0 microg/kg/min), respectively]. Intratubular or peritubular capillary administration of 10(-4) M KW-3902 completely suppressed TGF without affecting SFP0. TGF suppression and elevation of SFP0 during systemic A1 blockade indicated vasodilation, both in the afferent arteriole and more proximal preglomerular vessels. Inhibition of tubular Na reabsorption combined with TGF suppression allowed the marked natriuresis. TGF suppression through systemic, luminal, and peritubular application of the drug suggest that juxtaglomerular apparatus A1 receptors are important in the control of glomerular microcirculation.

Animals↗
PubMed1998

Doxorubicin cardiotoxicity: diastolic cardiac myocyte dysfunction as a result of impaired calcium handling in isolated cardiac myocytes.

We examined intracellular calcium transients of isolated single cardiac myocytes from rats with doxorubicin (DOX)-induced cardiomyopathy with simultaneous measurement of cell motion. DOX was administered i.p. to Sprague-Dawley rats at 2.5 mg/kg once a week for 10 weeks. Field-stimulated calcium transients and simultaneous cell motion in single myocytes were measured in the presence or absence of isoproterenol using fura-2/AM. Histopathologic examination revealed slight changes. The time courses of both calcium transients and cell motion were significantly prolonged by DOX. There was a slight but not significant reduction in parameters of contractility in both calcium transients and cell motion. The beta-adrenoceptor responsiveness of both calcium transients and cell motion was not significantly impaired compared with the controls. Our data indicated that, despite the slight histologic changes in the heart in DOX-induced cardiomyopathy, impaired sequestration of intracellular free calcium ions in individual myocytes may be one factor leading to diastolic dysfunction. Monitoring of diastolic function is important to detect early cardiotoxicity caused by DOX.

Animals↗
PubMed1998

Effects of lemildipine, a new calcium channel blocker, on renal microcirculation in SHR.

The effects of lemildipine, a new dihydropyridine calcium channel blocker, on renal hemodynamics and the tubuloglomerular feedback (TGF) mechanism were examined in anesthetized 9- to 10-wk-old spontaneously hypertensive rats (SHR). Lemildipine, 3 micrograms.kg-1 i.v., did not reduce mean blood pressure (MBP) but tended to increase GFR and increased urinary excretion of sodium (UNaV). Filtration fraction (FF) and fractional excretion of sodium (FENa) remained unaltered. An additional dose of lemildipine, 9 micrograms.kg-1 i.v., reduced MBP and renal vascular resistance. Renal plasma flow tended to increase, and GFR was unchanged. FF significantly fell. UNaV and FENa remained at the control level. Micropuncture experiments revealed that the maximal reduction in proximal stop-flow pressure (SFP), an index of glomerular capillary hydrostatic pressure (Pgc), induced by perfusion of the loop of Henle was significantly reduced by high-dose treatment (8.8 +/- 1.3 vs. 13.7 +/- 1.9 mmHg in control). A high dose of lemildipine induced a rightward and slightly upward shift of the TGF curve; the steady-state tubular flow rate (V1/2) was increased, the maximal slope of the curve decreased, and SFP at V1/2 unaltered. A low dose of lemildipine did not affect TGF response. These results indicate that lemildipine attenuates the TGF response in SHR by dilating afferent arterioles and thereby corrects the left and downward shift of the TGF curve in SHR. In addition, the fall in FF indicates lemildipine-induced efferent arteriolar vasodilatation. Through balanced systemic and glomerular vasodilatation, lemildipine maintains the levels of Pgc and GFR in the face of reduced renal perfusion pressure.

Animals↗
PubMed1997

Hedgehog and patched gene expression in adult ocular tissues.

We analysed the expression of members of the hh gene family in adult ocular tissues of newt, frog and mouse by RT-PCR method. Shh displayed restricted expression in the neural retina that was conserved in each species analyzed. X-bhh, X-chh and mouse Ihh were detected in the iris and in the retinal pigment epithelium, while mouse Dhh was detected additionally in the neural retina and faintly in the cornea. We also found that two types of ptc genes, potential hh targets and receptors, were expressed in these tissues, suggesting the presence of active hh signalling there.

Amino Acid Sequence↗
PubMed1997

[Synthesis and antibacterial properties of pyrido[2,3-b]pyrazine derivatives].

Novel pyrido[2,3-b]pyrazine 1,4-dioxide and pyrido [2,3-b]pyrazine 1-oxide derivatives were synthesized from furazano [4,5-b]pyridine 3-oxide and the enolic form of 1,3-diketones or beta-ketoesters catalyzed by silica gel or molecular sieves. Their antibacterial activities were evaluated. As the results of anti-bacterial screening tests in vitro, pyrido[2,3-b]pyrazine 1,4-dioxide derivatives revealed strong activities, but pyrido[2,3-b]pyrazine 1-oxide derivatives revealed no activities.

Anti-Bacterial Agents↗
PubMed1997

[Effects of cyclosporin A on the diurnal variation of blood pressure in patients with nephrotic syndrome].

We investigated the hemodynamic, renal, and hormonal effects of cyclosporin A (CyA) treatment (6 mg/kg per day) for 4 weeks in 12 patients with nephrotic syndrome (8 women: 4 men, aged 36-66 years, 3 cases of focal glomerular sclerosis: 9 cases of membranous nephropathy). To evaluate the effects of CyA on the diurnal variation of blood pressure (BP), 24-h non-invasive BP monitoring was performed using model ABPM-630 (Nihon Colin, Tokyo, Japan) before and during CyA treatment. As indices of hemodynamics, intra-arterial pressure was monitored and cardiac output was measured by the dye-dilution technique using a cuvette at 0 and 4 weeks after treatment. CyA ameliorated urinary protein excretion and hypoproteinemia from 3.5 +/- 0.9 to 2.2 +/- 0.7 g/day, and serum protein concentration from 4.9 +/- 0.2 to 5.5 +/- 0.2 g/dl after 4 weeks' treatment. Endogenous creatinine clearance, 24-h urinary sodium excretion, and plasma renin activity decreased significantly at 1 week. CyA treatment raised casual BP from 122 +/- 4/75 +/- 2 to 140 +/- 5/87 +/- 3 mmHg after 1 week and to 146 +/- 4/90 +/- 2 mmHg after 4 weeks. Before treatment 24-h ambulatory BP monitoring showed BP reduction at night (116 +/- 5/68 +/- 3 mmHg) compared to the daytime (124 +/- 5/75 +/- 2 mmHg). The diurnal variation of BP disappeared during CyA treatment; mean daytime and nighttime pressures were 135 +/- 4/81 +/- 2, 132 +/- 5/80 +/- 3 mmHg at 1 week and 139 +/- 5/83 +/- 3, 131 +/- 6/80 +/- 3 mmHg at 4 weeks, respectively. On hemodynamic study; a 4-week treatment with CyA increased mean arterial pressure from 91 +/- 3 to 104 +/- 3 mmHg, total peripheral resistance index from 2.1 +/- 0.1 to 2.5 +/- 0.1 x 10(3) dyne.sec.cm-5.m2, and unchanged heart rate and cardiac index. Serum Mg concentration decreased from 2.1 +/- 0.1 to 1.7 +/- 0.1 mg/dl. These results suggest that CyA-induced hypertension is characterized by the loss of nocturnal decline in blood pressure, which is accompanied by volume retention after 1 week and systemic vasoconstriction after 4 weeks.

Adult↗