Biomedical subjects

Y Kakinuma

Publications and source records attributed to Y Kakinuma.

At least 55 records · Page 3Linked to original sources

PubMed1997

Anti-apoptotic action of angiotensin fragments to neuronal cells from angiotensinogen knock-out mice.

The morphological analysis in a congenic line of angiotensinogen knock-out mice (AgKO) revealed the decreased density in granular layer cells of hippocampus and cerebellum, suggesting neuronal cells of AgKO susceptible to apoptotic cell death. This phenomenon was further studied by culture of the hippocampal neurons with decreased concentration of serum. AgKO neuronal cells, which showed apoptosis by lower concentration of the serum within several hours, however, survived much longer in the presence of angiotensin II (AII) and IV (AIV). This anti-apoptotic action was not interfered by AII receptor antagonists, CV11874 and PD123319. These results suggest that the renin-angiotensin system could play a critical role in central nervous system, preventing neuronal cells from apoptosis not only by AII but also AIV.

Angiotensin II↗

PubMed1997

Cardiovascular collapse through non-cholinergic mechanism after intravenous injection of N-methylcarbamate insecticide in rabbits.

This study was undertaken to investigate whether cholinesterase (ChE) inhibitor exerts cardiovascular collapse through non-cholinergic mechanism in halothane-anesthetized rabbits. Physostigmine and N-methylcarbamate insecticides (BPMC = 2-sec-butylphenyl methylcarbamate and PHC = propoxur = 2-isopropoxyphenyl methylcarbamate) were employed as ChE inhibitors. Intravenous injection of physostigmine produced a dose-related pressor response a few minutes after the injection. In contrast, the injection of BPMC elicited a dose-related depressor response during the injection. PHC produced a slight depressor response during the injection followed by a dose-dependent pressor response. Norepinephrine (NE)-induced pressor response was inhibited by the ChE inhibitors with the same order and magnitude as the depressor response. ECG of physostigmine or PHC was characterized by an increase in QRS voltage and a sinus bradycardia, and that of BPMC by a decrease in QRS voltage. Atropine pretreatment inhibited the pressor response, the increase in QRS voltage and the sinus bradycardia, but not the depressor response and the decrease in QRS voltage. From these observations, it is suggested that the pressor response is ascribed to the cholinergic mechanism (acetylcholine accumulation through ChE inhibition), but the depressor response may result from a non-cholinergic mechanism. It is also suggested that the difference in the cardiovascular response is determined by a balance between cholinergic and non-cholinergic activity of each ChE inhibitor.

Animals↗

PubMed1996

A second gene encoding a putative serine/threonine protein kinase which enhances spermine uptake in Saccharomyces cerevisiae.

We have isolated a new gene (PTK2) which restores spermine uptake of a polyamine uptake-deficient mutant of Saccharomyces cerevisiae (Kakinuma, Y., Maruyama, T., Nozaki, T., Wada, Y., Oshumi, Y., and Igarashi, K., 1995, Biochem, Biophys. Res. Commun. 216, 985-992). In magnesium-limited medium, the cell growth of a spermine-sensitive polyamine uptake mutant transformed with PTK2 recovered its sensitivity to spermine. The nucleotide sequence of the PTK2 gene indicated that it is identical with the YJR059W open reading frame of chromosome X encoding a putative serine/threonine protein kinase. The deduced amino acid sequence of the PTK2 gene product was 38% identical and 55% similar with that of the PTK1 (POT1) gene product, a putative serine/threonine protein kinase, which was found to enhance spermine uptake of the same mutant. The results indicate that polyamine transport of yeast is regulated by multiple phosphorylation/dephosphorylation pathways.

Amino Acid Sequence↗

PubMed1996

Intracellular Na+ regulates transcription of the ntp operon encoding a vacuolar-type Na+-translocating ATPase in Enterococcus hirae.

The Gram-positive bacterium Enterococcus hirae has a vacuolar-type Na+-translocating ATPase that is encoded by the ntp operon (ntpFIKECGABDHJ) (Takase, K., Kakinuma, S., Yamato, I., Konishi, K., Igarashi, K., and Kakinuma, Y. (1994) J. Biol. Chem. 269, 11037-11044). Primer extension experiments identified the start site of transcription of this operon upstream of the ntpF gene. In parallel with the increases of both Na+-pumping activity in whole cells and Na+-stimulated ATPase activity in the membranes, the amounts of the two major subunits (A and B) of this enzyme increased remarkably in cells grown on medium containing high concentrations of NaCl but not on medium containing KCl or sorbitol. Chloramphenicol completely abolished the increases of the enzyme activity and the amounts of A and B subunits, suggesting that the Na+-ATPase level increased by de novo synthesis of the enzyme with the stimulation of high concentrations of the external sodium ions. Finally, Western blot and Northern blot experiments revealed that the increase in the Na+-ATPase level with the external Na+ was further accelerated by addition of an ionophore, such as monensin, which rendered the cell membrane permeable to Na+. These results suggest that the transcription of the Na+-ATPase operon is regulated by the intracellular concentration of sodium ions.

Adenosine Triphosphatases↗

PubMed1996

Enhancement of helicase activity and increase of eIF-4E phosphorylation in ornithine decarboxylase-overproducing cells.

In mouse FM3A ornithine decarboxylase (ODC) overproducing cells (EXOD-1), the amount of ODC protein was approximately 100-fold that of normal cells. Since it is well known that the translational efficiency of ODC mRNA is very low and that eIF-4E is a limiting factor for the mRNA recognition and the scanning of 40 S ribosomal subunits, we measured the amount and phosphorylation of eIF-4E in EXOD-1 cells. An increase in the phosphorylation of eIF-4E, its association with p220 protein, and an enhancement of RNA helicase activity were observed in the cells. These results support the hypothesis that phosphorylation of eIF-4E enhances RNA helicase activity through eIF-4F (4A, 4E, and p220) complex formation.

Animals↗

PubMed1996

The ntpJ gene in the Enterococcus hirae ntp operon encodes a component of KtrII potassium transport system functionally independent of vacuolar Na+-ATPase.

The ntpJ gene, the tail end in the vacuolar type Na+-ATPase (ntp) operon of Enterococcus hirae, encodes a putative 49-kDa hydrophobic protein resembling K+ transporter protein in Saccharomyces cerevisiae (Takase, K., Kakinuma, S., Yamato, I., Konishi, K., Igarashi, K., and Kakinuma, Y. (1994) J. Biol. Chem. 269, 11037-11044). Northern blotting experiment revealed that the ntpJ gene was transcribed as a cistron in the ntp operon. We constructed an Enterococcus strain in which the ntpJ gene was disrupted by cassette mutagenesis with erythromycin resistance gene. The growth of this mutant was normal at low pH. However, the mutant did not grow at high pH in K+-limited medium (less than 1 mM), while the wild type strain grew well; the internal K+ concentration of this mutant was as low as 7% of that of the wild type strain, suggesting that the K+ accumulation at high pH was inactivated by disruption of the ntpJ gene. Potassium uptake activity via the KtrII system, which had been proposed as the proton potential-independent, Na+-ATPase-coupled system working at high pH (Kakinuma, Y., and Harold, F. M. (1985) J. Biol. Chem. 260, 2086-2091), was missing in this mutant strain. However, this mutant retained as high activities of Na+-ATPase and Na+ pumping as the wild type strain. From these results, we conclude that the NtpJ is a membraneous component of the KtrII K+ uptake system but not a functional subunit of vacuolar Na+-ATPase complex; the interplay between the KtrII system and the Na+-ATPase was discussed.

Adenosine Triphosphatases↗

PubMed1996

[Successful gamma-globulin pulse therapy of a young child with acquired pure red cell aplasia].

We report a case of a 2 years and 2 months old male, who showed a normochromic normocytic anemia, Hb 3.7g/dl. The bone marrow aspiration revealed a remarkable decrease of erythroblasts alone. Because of none of other underlying diseases identified, it leads to a diagnosis of acquired idiopathic pure red cell aplasia (PRCA). Pulse therapy of methylprednisolone, followed by one month administration of prednisone did not lead to a remission. However, high dose of gamma-globulin pulse therapy restored erythropoiesis in several days, with a rate of hemoglobin increment of 0.5 g/dl/day. 2.5 years after the onset of PRCA, the patient has neither suffered from complications of hematological diseases, nor undesired consequences of the therapy. Although recent advance of therapy regarding PRCA has focussed on cyclosporine A, high dose of gamma-globulin pulse therapy with a remarkable effect is worth as an alternative.

Child, Preschool↗

PubMed1995

Cloning of the gene encoding a putative serine/threonine protein kinase which enhances spermine uptake in Saccharomyces cerevisiae.

Polyamine uptake in Saccharomyces cerevisiae was modulated by extracellular magnesium; in a magnesium-limited medium, polyamine, especially spermine, was overaccumulated into the interior, whose level was then toxic for the growth of this organism (Maruyama, T., Masuda, N., Kakinuma, Y., and Igarashi K. (1994) Biochim. Biophys. Acta 1194, 289-295). Here we isolated a mutant (strain YTM22-8) whose growth was tolerant to spermine in magnesium-limited medium. This mutant was defective in polyamine uptake and did not overaccumulate spermine. From a yeast genome library we cloned a gene (POT1) which restored the spermine uptake of this mutant and the sensitivity of the growth to spermine. The nucleotide sequence of the POT1 gene indicated that it encodes a putative serine/threonine protein kinase and is located on chromosome XI. The results suggest that spermine uptake by this organism is probably regulated by phosphorylation and dephosphorylation.

Amino Acid Sequence↗

PubMed1995

Electrogenic Na+ transport by Enterococcus hirae Na(+)-ATPase.

Energy-dependent generation of a membrane potential (delta psi) (-45 mV, interior negative) was observed in the F0F1, H(+)-ATPase-defective mutant of Enterococcus hirae. The generation of delta psi was found at high pH (but not at low pH), for which intracellular Na+ was required but not extracellular K+. The delta psi-generating activity was induced in cells cultured in media containing high concentrations of Na+, and was not observed in the Na(+)-ATPase mutants. These results suggest that E. hirae Na(+)-ATPase is responsible for the electrogenic sodium pump.

Adenosine Triphosphatases↗

PubMed1995

Totally implantable ventricular assist system using a vibrating flow pump.

A totally implantable ventricular assist system (VAS), including a drive system and a percutaneous electric energy transmission system, was developed and evaluated in acute animal experiments using adult goats. This newly designed VAS mainly consists of a vibrating tube, coils, magnets, and a jelly-fish valve as the outlet valve. For energy transmission, a new implantable transmitter with a plain weave structure was proposed as a noncontacting transform by using the spinal amorphous magnetic fibers. The fluid mechanical and hemodynamic properties and the efficiency of the energy transmission system were evaluated in acute animal experiments using healthy adult goats. This vibrating electromagnetic artificial heart (AH) could generate more than 10 L/min as output volume, with 10 Hz vibration using 20 volts as supplied voltage. The total efficiency of the percutaneous energy transmission system was 76%, and temperature increases were within the acceptable range, suggesting the usefulness of our newly developed implantable VAS.

Animals↗

PubMed1995

Fractal dimension analysis of the oscillated blood flow with a vibrating flow pump.

To analyze the hemodynamic parameters during circulation with oscillated blood flow, nonlinear mathematical analyzing techniques, including fractal theory, were utilized. Vibrating flow pumps (VFP) were implanted as a left heart bypass, and the ascending aorta was clamped to constitute the total left heart circulation with oscillated blood flow in acute animal experiments using 7 adult goats. Using nonlinear mathematical analyzing techniques, reconstructed attractors of the arterial blood pressure waveform in the phase space during natural circulation and oscillated circulation were analyzed. Using the Grassberger-Procaccia correlation dimension analyzing technique, fractal dimension analysis of the reconstructed attractor was performed. During VFP bypass, lower fractal dimensions of the reconstructed attractor were shown compared with those during natural heart circulation. The results suggest that lower dimensional chaotic dynamics contributed to the circulation with oscillated blood flow.

Animals↗

PubMed1995

Potassium/proton antiport system of growing Enterococcus hirae at high pH.

The cytoplasmic pH (pHin) of Enterococcus hirae growing at pH 9.2 was maintained at about 8.1. Membrane-permeating amines such as ammonia alkalinized the pHin from 8.1 to 9.0 at a high concentration and induced K+ extrusion. The pHin alkalinization was transient; the pHin fell from 9.0 to the original value of pH 8.1, at which point K+ extrusion ceased, and remained constant. Cells accumulated ammonium ion to an extent stoichiometrically equivalent to the K+ loss. This bacterium continued to grow well under this condition. These results suggest that the pHin-responsive primary K+/H+ antiport system (Y. Kakinuma, and K. Igarashi, J. Biol. Chem. 263:14166-14170, 1988) works for the pHin regulation of this organism growing at a high pH.

Amines↗

PubMed1995

Chaotic behavior of hemodynamics with ventricular assist system.

In order to analyze hemodynamic parameters during left ventricular assistance as an entity and not as decomposed parts, non-linear mathematical techniques were utilized. Pneumatically actuated ventricular assist systems (VAS) were implanted as left heart bypasses in acute animal experiments, using healthy adult mongrel dogs. By the use of the non-linear mathematical technique, the arterial blood pressure waveform (AP) was embedded into the four-dimensional phase space and projected into the three-dimensional phase space. The Lyapunov numerical method was used as an adjunct to the graphical analysis of the state space. The phase portrait of the attractor showed a complex structure; a three dimensional solid torus with a screw type structure as a part, suggesting deterministic chaos in the AP without left ventricular assistance. Positive lyapunov exponents confirmed the existence of chaos. During counterpulsation mode left ventricular assistance, the phase portrait of the attractor showed a more complex structure, and positive Lyapunov exponents suggested a greater dimensional deterministic chaos. However, non-structured patterns were seen in the phase space during internal mode VAS driving, suggesting the possibility of dissipative dynamics in the four dimensional phase space. These results suggest that the cardiovascular system with counterpulsation mode VAS driving is in a homeochaotic state, which is thought to be a flexible and intelligent control system. And there is greater dimensional complex dynamics in the circulatory regulatory system with VAD during internal mode assistance.

Animals↗

PubMed1995

Can the artificial heart make the circulation become fractal?

In order to analyze the hemodynamic parameters in prosthetic circulation as an entity and not as decomposed parts, non linear mathematical analyzing techniques, including the fractal dimension analyzing theory, were utilized. Two pneumatically actuated ventricular assist devices were implanted, as biventricular bypasses (BVB), in chronic animal experiments, using four healthy adult goats. For the comparison between the natural and prosthetic circulation in the same animals, the BVB type complete prosthetic circulation model with ventricular fibrillation, was adopted. All hemodynamic parameters with natural and prosthetic circulation were recorded under awake conditions, and calculated with a personal computer system. Using the non-linear mathematical technique, the arterial blood pressure waveform was embedded into the return map as the beat-to-beat time series data and fractal dimension analysis were performed to analyze the reconstructed attractor. By the use of the Box counting method, fractal dimension analysis of the hemodynamics was performed. Return map of the hemodynamics during natural and artificial circulation showed fractal characteristics, and fractal dimension analysis of the arterial blood pressure revealed the fact that lower dimensional fractal dynamics were evident during prosthetic circulation. Fractal time series data is suggested to have robustness and error resistance, thus our results suggest that the circulatory regulatory system with an artificial heart may have these desired characteristics.

Animals↗

PubMed1994

Non-cholinergic lethality following intravenous injection of carbamate insecticide in rabbits.

This study was undertaken to investigate the possibility that non-cholinergic mechanism accounts for acute lethality of cholinesterase (ChE) inhibitor. Physostigmine and carbamate insecticides (2-s-butylphenyl methylcarbamate (BPMC); isoprocarb, 2-isopropylphenyl methylcarbamate (MIPC); and propoxur, 2-isopropoxyphenyl methylcarbamate (PHC)) were employed as ChE inhibitors. Rabbits intravenously given any of the ChE inhibitors showed typical signs of anti-ChE poisoning, a marked inhibition of systemic ChE activity, and an increase in RR interval on an ECG. Injection of physostigmine or PHC at a lethal dose produced a pressor response before cessation of spontaneous breathing. In contrast, injection of MIPC or BPMC primarily elicited a cardiovascular collapse, characterized by a rapid and progressive decrease in blood pressure and a decrease in QRS amplitude of ECG, before cessation of spontaneous breathing. The atropine pretreatment inhibited the pressor response, but not the depressor response and the QRS change. The pretreatment antagonized acute lethality of the ChE inhibitors except BPMC. It is suggested that the mode of lethality for intravenous ChE inhibitor could be determined by a balance between anti-ChE activity and some mechanism other than ChE inhibition. BPMC produced acute lethality through the latter mechanism rather than the former one.

Animals↗

PubMed1994

Polyamine-sensitive magnesium transport in Saccharomyces cerevisiae.

In Saccharomyces cerevisiae we found a toxic effect of polyamines, well-known metabolites important for cell proliferation; in magnesium-limited (50 microM Mg2+) synthetic medium, cell growth was severely inhibited by spermine, spermidine and putrescine in descending order. In conjunction with a decrease in the growth rate by the addition of 0.5 mM spermine, the internal Mg2+ content decreased and the spermine content increased. When cell growth ceased, the Mg2+ content had finally decreased to about 40% of the value before the addition of spermine (120-130 nmol/mg dry weight), and the spermine content concomitantly increased 30-fold (from 1 to 30 nmol/mg dry weight); spermine4+ apparently took the internal place of Mg2+ with a probable stoichiometry of 1:2. However, the total amount of Mg2+ retained in the cells remained constant even with the addition of spermine, suggesting that spermine blocks Mg2+ accumulation. In high (2 mM) Mg2+ medium, cell growth was hardly affected by polyamines, and an exchange of spermine and Mg2+ was minimal. Energy-dependent Mg2+ uptake by whole cells was inhibited by spermine, spermidine and putrescine in a similar manner as the growth rates. On the other hand, Mg2+ inhibited spermine uptake. These results suggest that competition takes place between extracellular spermine and Mg2+ for their accumulations. It is thus clear that polyamine-sensitive Mg2+ transport system is indispensable for the physiology of this organism.

Biological Transport↗

PubMed1994

Sequencing and characterization of the ntp gene cluster for vacuolar-type Na(+)-translocating ATPase of Enterococcus hirae.

We have previously reported the DNA and amino acid sequences for the three genes (ntpA, ntpB, and ntpK) encoding the A, B, and K (proteolipid) subunits, respectively, of Na(+)-translocating ATPase of a eubacterium Enterococcus hirae (Kakinuma, Y., Kakinuma, S., Takase, K., Konishi, K., Igarashi, K., and Yamato, I. (1993) Biochem. Biophys. Res. Commun. 195, 1063-1069). In this paper we report the entire nucleotide sequence of the ntp gene cluster coding for this multisubunit enzyme. The cluster contained eight other genes; the order of these 11 genes was ntpF, -I, -K, -E, -C, -G, -A, -B, -D, -H, and -J, encoding proteins with predicted molecular weights of 14,255, 75,619, 16,036, 22,699, 38,162, 11,409, 65,766, 51,139, 27,093, 7,164, and 48,869, respectively. The deduced amino acid sequences of these products suggested that NtpI and NtpJ are hydrophobic proteins and others are hydrophilic. The ntpI gene product, which possesses six membrane-spanning segments in its carboxyl-terminal half, resembled the 116-kDa subunit of vacuolar (V)-ATPase in clathrin-coated vesicles. In addition, the NtpE, NtpC, NtpG, and NtpD proteins resembled bovine kidney ATPase E subunit, Saccharomyces cerevisiae Vma6p, Manduca sexta V-ATPase 14-kDa subunit, and Sulfolobus acidocaldarius gamma subunit, respectively, although the similarities between their amino acid sequences were moderate. Other gene products (NtpF and NtpH) did not show significant sequence similarity to other V-ATPase subunits. Since NtpA, NtpB, and NtpK are homologous counterparts of V-ATPase, these findings suggest that the molecular architecture of E. hirae Na(+)-ATPase complex corresponds to the V-type H(+)-ATPase complex distributed in various eukaryotic endomembrane systems. The sequence of the NtpJ product was similar to those of K+ transport systems of S. cerevisiae (Trk1 and Trk2); its meaning will be discussed. This is the first demonstration of a eukaryotic V-ATPase-like Na+ pump in bacteria.

Adenosine Triphosphatases↗

PubMed1994

Purification and characterization of the catalytic moiety of vacuolar-type Na(+)-ATPase from Enterococcus hirae.

We have previously reported the molecular cloning and sequences of the ntp genes for Enterococcus hirae Na(+)-translocating ATPase [Takase, K., Kakinuma, S., Yamato, I., Konishi, K., Igarashi, K., and Kakinuma, Y. (1994) J. Biol. Chem. 269, 11037-11044]; the expected structure of this enzyme complex resembles those of the vacuolar H(+)-ATPase complexes in eukaryotes. In this paper we report purification and characterization of the catalytic moiety of Na(+)-ATPase, whose molecular size was about 400 kDa, consisting of polypeptides of 69 kDa (NtpA), 52 kDa (NtpB), and 29 kDa (NtpD) with a probable stoichiometry of 3:3:1. Purified enzyme hydrolyzed GTP as the best substrate (GTP > CTP > UTP > ATP), and the activity was maximal at around pH 6.0. The activity was not stimulated by sodium ions, and was selectively inhibited by nitrate. These properties were different from those of membrane-bound Na(+)-ATPase, suggesting that a significant conformational change of the catalytic moiety may take place upon dissociation from the membrane-embedded moiety and probably also loss of other hydrophilic subunits. Antiserum against purified enzyme inhibited the Na(+)-stimulated ATPase activity of the membranes. Immunoblotting analysis revealed that the change in the amounts of A and B subunits of the membranes paralleled that of the Na(+)-ATPase activity. Furthermore, the A subunit was missing in the membranes of a Na(+)-ATPase mutant, and recovered in those of its revertant. These immunochemical data are consistent with the notion that this enzyme is the hydrophilic catalytic moiety of the V-type Na(+)-ATPase in E. hirae.

Adenosine Triphosphatases↗