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Biomedical subjects

Y Terada

Publications and source records attributed to Y Terada.

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

A method for analysis of cell to cell transmission of Theileria sergenti piroplasms.

We tried to develop an experimental system for quantifying piroplasm transmission in Theileria sergenti infection using a SCID mouse model, of which red blood cells (RBC) had been substituted with bovine (Bo). A mouse hybridoma cell producing antibody against Holstein RBC was established for distinguishing Holstein RBC from Japanese Black RBC by a immuno-staining method. T. sergenti piroplasms in RBC were stained by 4',6-diamidino-2-phenylindole. With the aid of these techniques the piroplasm transmission from one to another race of Bo-RBCs could successfully be quantified in SCID mice.

Animals↗
PubMed1998

Growth hormone improves mouse embryo development in vitro, and the effect is neutralized by growth hormone receptor antibody.

We investigated whether growth hormone(GH) may influence the development of mouse embryo in vitro using recombinant GH and anti-growth hormone receptor(GHR) antibody. When mouse two-cell-stage embryos were cultured with GH, 5, 10 mIU/ml, the rates of formation of both blastocysts and of hatched blastocysts from two-cell-stage embryos were significantly higher than in the medium without GH. The number of blastomeres from blastocyst treated with GH, 2, 5 and 10 mIU/ml, was significantly higher than those cultured without GH. When cultured blastocysts were implanted in recipient uteri, a significantly higher implantation rate was found for the GH-treated(10 mIU/ml) mouse embryos than for controls. To confirm the GH effect, anti-GHR monoclonal antibody MAb5 was employed to neutralize the action of GH through GHR. Two-cell-stage mouse embryos were cultured with GH, 10 mIU/ml, and anti-GHR antibody, and as a control, embryos were cultured with GH alone. Both the rate of formation of blastocysts from two-cell-stage embryos and the number of blastomeres were significantly decreased in groups exposed to anti-GHR antibody. Results indicate that GH may be important to early embryonic development, acting through GHR. GH may help to obtain good quality embryos and improve the implantation rate in IVF programs.

Animals↗
PubMed1998

Lovastatin inhibits mesangial cell proliferation via p27Kip1.

Mesangial cell proliferation is a key feature of glomerulonephritis. The hydroxymethylglutaryl-coenzyme A reductase inhibitor lovastatin is known to inhibit cell cycle progression. To determine the inhibitory mechanisms of mesangial cell proliferation by lovastatin, the cyclin-dependent kinase (CDK) activity, and expression of CDK inhibitor (p27Kip1, p21Cip1, and p16INK4) mRNA and protein were measured. Lovastatin inhibited phosphorylation of retinoblastoma protein and mesangial cell proliferation dose dependently. Lovastatin increased the p27Kip1 protein level but produced no changes in the abundance of the p27Kip1 mRNA level both in the presence and absence of mitogens. Treatment with lovastatin revealed the increment of both CDK2- and CDK4-bound-p27Kip1. The experiment using antisense oligonucleotide against p27Kip1 showed significant amelioration of lovastatin-induced cell cycle arrest. Lovastatin reduced both platelet-derived growth factor-stimulated CDK2 and CDK4 kinase activities. In conclusion, lovastatin inhibited mesangial proliferation via translational upregulation or impairment of p27Kip1 protein degradation. Lovastatin serves as a potential therapeutic approach to mesangial proliferative disease.

Animals↗
PubMed1998

Setting time and sealing ability of alpha-tricalcium phosphate cement containing titanic oxide.

We developed a new type of calcium phosphate cement for clinical use in endodontics as a root canal sealer or pulp cupping agent. The solid phase of the sealer is composed of 70% of alpha-tricalcium phosphate (alpha-TCP) and 30% of titanic oxide (TiO2), and the liquid phase is 37% citric acid, 5% tannic acid and 58% distilled water. TiO2 was added to control setting time and handling of the cement. We used commercially available calcium phosphate root canal sealer as a control. ISO standards specify that new endodontic products should be examined thoroughly before clinical use. It is important to carry out in vitro cytotoxicity and in vivo histocompatibility tests. We first did in vitro test of setting time and root canal sealing ability of the cement. We found that this developed calcium phosphate cement had an appropriate setting time and excellent sealing ability as a root canal sealer, and concluded that it was suitable for clinical use as a root canal sealer.

Calcium Phosphates↗
PubMed1998

Right thoracotomy as an alternative for redo mitral valve replacement and concomitant repair of the tricuspid valve.

BACKGROUND: We report the results of a right thoracotomy for reoperation on the mitral plus concomitant procedures. Access to aorta or repair of other lesions by this approach is controversial. EXPERIMENTAL DESIGN AND SETTING: Retrospective study. Institutional practice (University of Tsukuba Hospital, Tsukuba Japan). METHODS: Until 1995, 9 patients underwent right thoracotomy for mitral reoperation. The indication for this approach was no retrosternal space with the pericardium left open. Seven patients had deteriorated bioprosthesis, 1 periprosthetic valve leakage, and 1 re-stenosis. Four were associated with moderate tricuspid regurgitation. Operations were performed under fibrillation. Cardioplegia was used in 1. RESULTS: Through thoracotomy, 4 underwent mitral valve re-replacement, and 4 mitral valve re-replacement plus tricuspid annuloplasty. One was abandoned because of severe pleural adhesion. No neurological injury, or perioperative myocardial infarction occurred. CONCLUSIONS: The right thoracotomy was an effective alternative to repeat sternotomy for redo mitral valve operation. Also, concomitant repair of the tricuspid valve could be safely done by this approach.

Aged↗
PubMed1997

Evidence for the involvement of Na+-K+ pump and K+ conductance in the post-tetanic hyperpolarization of the tetrodotoxin-resistant C-fibers in the isolated bullfrog sciatic nerve.

The post-tetanic hyperpolarizations (PTHPs) were recorded from the isolated bullfrog sciatic nerves using a modified vaseline gap method. Repetitive stimulation of tetrodotoxin-resistant (TTX-R) C-fibers produced frequency- and activity-dependent PTHPs. The ouabain solutions (0.1 mM), the solutions (0.1 mM ouabain + 2 mM tetraethylammonium (TEA)) and 5 mM TEA solutions reduced the PTHP amplitude to 56.2 +/- 10.7% (mean +/- SD, n = 9), to 37.0 +/- 12.3% (n = 8), to 76.0 +/- 10.9% (n = 5) of the control value, respectively. Each pair of the three solutions revealed a significant difference in their effects on the PTHP (P < 0.01). Furthermore, the Li-Ringer solutions and the solutions (Li-Ringer + 2 mM TEA) reduced the PTHP amplitude as well, thus resembling ouabain effects. These results strongly suggest that the repetitive stimulation of TTX-R C-fibers activates the membrane Na+-K+ pump resulting in a major part of the PTHP and induces TEA-sensitive K+ conductance composing a minor part of the PTHP, which might modulate repetitive firing of TTX-R C-fibers.

Action Potentials↗
PubMed1997

Aprotinin inhibits plasmin-induced platelet activation during cardiopulmonary bypass.

BACKGROUND: In the past few years, aprotinin has been used in cardiac surgery with impressive results of reducing blood loss, but several adverse effects of aprotinin also have been reported. One of the most likely mechanisms is the inhibition of plasmin by aprotinin, although this indirect effect has not been reproduced in all experimental studies. METHODS AND RESULTS: We evaluated the platelet function and fibrinolytic activity during human cardiac surgery, with or without aprotinin. During cardiopulmonary bypass (CPB) in humans without aprotinin (n=16), decrease of platelet aggregation induced by thrombin, increase of alpha-granule secretion of platelet and microparticle formation, and increase of plasmin/alpha2-antiplasmin complex (PIC) were observed. In contrast, low-dose aprotinin (1.0 x 10(6) KIU), which was administered only into the priming fluid of extracorporeal circuits (n=10), maintained platelet aggregation induced by thrombin and reduced alpha-granule secretion and microparticle formation of platelets during CPB. In vitro, plasmin (0.8 CU/mL) released alpha-granules of washed platelets, and this activation was completely inhibited by aprotinin (10 KIU/mL). CONCLUSIONS: Aprotinin has indirect effects to inhibit platelet activation, and this may partly explain the reduction of blood loss during cardiac surgery. To prevent the adverse effects, a single and minimal use of aprotinin is important. The results of in vivo and in vitro studies suggest that platelet preservation was demonstrated by the lower concentration of aprotinin (1.0 x 10(6) KIU per patient or 10 KIU/mL) compared with the concentration that inhibits plasma fibrinolysis.

Aged↗
PubMed1997

Cyclodextrins are not the major cyclic alpha-1,4-glucans produced by the initial action of cyclodextrin glucanotransferase on amylose.

The initial action of cyclodextrin glucanotransferase (CGTase, EC 2.4.1.19) from an alkalophilic Bacillus sp. A2-5a on amylose was investigated. Synthetic amylose was incubated with purified CGTase then terminated in the very early stage of the enzyme reaction. When the reaction mixture was treated with glucoamylase and the resulting glucoamylase-resistant glucans were analyzed with high performance anion exchange chromatography, cyclic alpha-1,4-glucans, with degree of polymerization ranging from 9 to more than 60, in addition to well known alpha-, beta-, and gamma-cyclodextrin (CD), were detected. The time-course analysis revealed that larger cyclic alpha-1, 4-glucans were preferentially produced in the initial stage of the cyclization reaction and were subsequently converted into smaller cyclic alpha-1,4-glucans and into the final major product, beta-CD. CGTase from Bacillus macerans also produced large cyclic alpha-1, 4-glucans except that the final major product was alpha-CD. Based on these results, a new model for the action of CGTase on amylose was proposed, which may contradict the widely held view of the cyclization reaction of CGTase.

Amylose↗
PubMed1997

A target of phosphatidylinositol 3,4,5-trisphosphate with a zinc finger motif similar to that of the ADP-ribosylation-factor GTPase-activating protein and two pleckstrin homology domains.

We have purified a protein that binds phosphatidylinositol 3,4,5-trisphosphate [PtdIns(3,4,5)P3] using beads bearing a PtdIns(3,4,5)P3 analogue. This protein, with a molecular mass of 43 kDa, was termed PtdIns(3,4,5)P3-binding protein. The partial amino acid sequences were determined and a full-length cDNA encoding the protein was isolated from bovine brain cDNA library. The clone harbored an open reading frame of 373 amino acids which contained one zinc finger motif similar to that of ADP-ribosylation-factor GTPase-activating protein and two pleckstrin homology domains. The entire sequence was 83% similar to centaurin alpha, another PtdIns(3,4,5)P3-binding protein. The protein bound PtdIns(3,4,5)P3 with a higher affinity than it did inositol 1,3,4,5-tetrakisphosphate, phosphatidylinositol 4,5-bisphosphate, phosphatidylinositol 3,4-bisphosphate, and phosphatidylinositol 3-phosphate suggesting that the binding to PtdIns(3,4,5)P3 was specific. The binding activity was weaker in the mutants with a point mutation in the conserved sequences in each pleckstrin homology domain. Introduction of both mutations abolished the activity. These results suggest that this new binding protein binds PtdIns(3,4,5)P3 through two pleckstrin domains present in the molecule.

ADP-Ribosylation Factors↗
PubMed1997

Immunocytochemical study of cathepsin L and rat salivary cystatin-3 in rat osteoclasts treated with E-64 in vivo.

The localization of cathepsin L and rat salivary cystatin-3 (RSC-3) in rat osteoclasts (rat femoral and alveolar bones) treated with or without E-64 (control) was examined immunocytochemically. In osteoclasts pretreated with E-64, immunoreactivity for cathepsin L was very weak extracellularly compared to that in the control osteoclasts. However, it was strong intracellularly. The localization of RSC-3 was unclear in the control osteoclasts, while in E-64 treated osteoclasts, both the clear zone and ruffled border areas showed a very strong immunoreaction. At the electron-microscopic level, in normal osteoclasts, numerous immunoreaction products for cathepsin L were found extracellularly in the bone matrix under the ruffled border, while few intracellular products were observed. In contrast, in the E-64-treated osteoclasts, only a few immunoreaction products were found extracellularly, while intracellularly cathepsin L was found in numerous endosome-lysosomal vacuoles. In the immunoreaction for RSC-3, the cytoplasm of the ruffled border was positive, and the tips of the RSC-3-positive ruffled border appeared to enter deeply into the bone matrix. Intracellularly, the granular reaction products of RSC-3 were found in the vacuoles (probably autophagolysosomes). Thus, in E-64-treated osteoclasts, inhibition of the extracellular release of cathepsin L was demonstrated. In addition, intralysosomal accumulation of RSC-3 and deep penetration of the RSC-3-positive ruffled border into the bone matrix were found. These findings suggest that RSC-3 is associated with the inhibition of cathepsin L in both the lysosomes (in the osteoclasts) and bone matrix.

Animals↗
PubMed1997

Microlocalization and effects of adrenomedullin in nephron segments and in mesangial cells of the rat.

We examined microlocalization of mRNA coding for adrenomedullin (AM), using reverse transcription-polymerase chain reaction (RT-PCR), and the effects of AM on adenosine 3',5'-cyclic monophosphate (cAMP) generation and water transport in microdissected rat nephron segments. We also examined intraglomerular site of the expression of AM and AM-stimulated cAMP generation in cultured rat mesangial cells (MC). RT-PCR demonstrated the signals for AM mRNA in glomerulus (Glm), cortical collecting duct (CCD), outer medullary collecting duct (OMCD), and inner medullary collecting duct (IMCD) but not in proximal convoluted tubule (PCT) or medullary thick ascending limb (MTAL). AM (10(-7) M) stimulated cAMP generation in Glm >> CCD = IMCD > OMCD but not in PCT or MTAL, which corresponded to the results of the expression of AM mRNA. AM (10(-8) M) slightly increased osmotic water permeability by 24% in perfused terminal IMCD. Northern blot analysis revealed high expression of AM mRNA in MC. AM (10(-7) M) stimulated cAMP generation in MC both in the presence and absence of fetal calf serum, suggesting that AM-dependent cAMP generation was evident both in cycling MC and in quiescent MC. AM may work as a diuretic peptide mainly by increasing glomerular filtration rate via cAMP in MC.

Adrenomedullin↗
PubMed1997

Characteristics of neurons with high-frequency discharge in the central nervous system and their relationship to chronic pain. Experimental and clinical investigations.

High-frequency extracellular unitary activity was recorded mainly in the ventral caudal nucleus of the thalamus in chronic-pain patients. These high-frequency discharge (hyperactive) neurons shows three types of discharge pattern with different interval histograms. Some of these hyperactive neurons were suppressed by the administration of a calcium antagonist (nicardipine). In an experimental study, chronic-pain models were made in rats according to the method of Lombard et al. (1979). From these animals, hyperactive neurons were recorded from the contralateral thalamic nuclei, lemniscus medialis. Hyperactive neurons were examined via electrical stimulation of and/or iontophoretic application. The results suggest that there is some relationship to the glutamatergic and GABAergic (probably GABAA) fibers or receptors.

Animals↗
PubMed1997

A polymorphism observed in the experimentally successful peptide vaccine sequence derived from Theileria sergenti piroplasm major surface antigen (p33).

A polymorphism in the experimentally successful peptide vaccine sequence (EVVWKEKKEVKDLDA, amino acids 134-148) derived from the 33 kDa piroplasm major surface antigen (p33) of Theileria sergenti was examined. The vaccine sequences obtained by PCR amplification and sequencing of the p33 gene from a total of 15 parasite-infected cattle blood samples collected from 4 prefectures through Hokkaido to Kumamoto revealed the two major sequences (Ikeda and Chitose stock types) either of which was identified in all samples. Since the peptide vaccine develops the parasite species- or stock-specific immunity in the animals, an application of the two major peptide sequences as cocktailed vaccine should be evaluated for a practical use of this strategy to controlling T. sergenti infection in Japan.

Amino Acid Sequence↗
PubMed1997

A case of unilateral diaphragmatic eventration treated by plication with thoracoscopic surgery.

A 56-year-old woman underwent plication with U-stitches by thoracoscopic surgery for left diaphragmatic eventration. Marked improvement in left lung expansion, normalization of the position of the left diaphragm on chest radiograph, and improvement of pulmonary function and dyspnea on exertion have been maintained for 2 years. Plication for diaphragmatic eventration should be performed with minimally invasive surgery.

Diaphragmatic Eventration↗
PubMed1997

Overexpression of cell cycle inhibitors (p16INK4 and p21Cip1) and cyclin D1 using adenovirus vectors regulates proliferation of rat mesangial cells.

To elucidate the mechanisms of the cell cycle of mesangial cells, adenovirus vectors containing coding sequences of cyclin D1 (AxCAD1), p16INK4 (AxCAp16) and p21Cip1 (AxCAp21) were produced and investigated to determine whether transfer of these genes changes serum- and PDGF-induced proliferation of rat mesangial cells. Efficiency of the transfer of the genes was examined by Northern and Western blot analyses. The cell cycle of mesangial cells was evaluated by measurement of [3H]-thymidine incorporation, flow cytometry, and cyclin-dependent kinase 4 kinase assay. Expression of cyclin D1, p16INK4 and p21Cip1 was observed from 24 h after the infection, and the expression increased up to 48 h. AxCAp16 and AxCAp21 caused a significant inhibition in the [3H]-thymidine incorporation to 47% and 76%, respectively. AxCAp16 and AxCAp21 also inhibited the mitogen-induced increase in cyclin-dependent kinase 4 kinase activity and reduced the percentage of cells in S phase. Coinfection of AxCAp16 with AxCAp21 showed no additive inhibition. Overexpression of cyclin D1 reduced cell size and increased the percentage of the cells in S and G2 phase. These findings suggest that p16INK4 and p21Cip1 function as inhibitors of the proliferation of mesangial cells induced by growth-promoting factors and that deregulated expression of cyclin D1 causes cell cycle disturbances. Adenovirus-mediated gene transfer of p16INK4 and p21Cip1 serves as a potential therapeutic approach to mesangial proliferative diseases.

Adenoviruses, Human↗