E Tanaka

HAMAMATSU Photonics K.K., Hamamatu, Shizuoka, Japan

Are you E Tanaka?

Claim your profile

Publications (72)154.57 Total impact

  • Annals of the Rheumatic Diseases 01/2014; 71(Suppl 3):672-672. DOI:10.1136/annrheumdis-2012-eular.589 · 9.27 Impact Factor
  • Annals of the Rheumatic Diseases 01/2014; 72(Suppl 3):A599-A600. DOI:10.1136/annrheumdis-2013-eular.1785 · 9.27 Impact Factor
  • Annals of the Rheumatic Diseases 01/2014; 71(Suppl 3):496-496. DOI:10.1136/annrheumdis-2012-eular.3026 · 9.27 Impact Factor
  • Annals of the Rheumatic Diseases 01/2014; 72(Suppl 3):A627-A627. DOI:10.1136/annrheumdis-2013-eular.1861 · 9.27 Impact Factor
  • Annals of the Rheumatic Diseases 01/2014; 72(Suppl 3):A117-A117. DOI:10.1136/annrheumdis-2013-eular.396 · 9.27 Impact Factor
  • Annals of the Rheumatic Diseases 01/2014; 72(Suppl 3):A314-A314. DOI:10.1136/annrheumdis-2013-eular.970 · 9.27 Impact Factor
  • Annals of the Rheumatic Diseases 01/2014; 71(Suppl 3):505-505. DOI:10.1136/annrheumdis-2012-eular.3050 · 9.27 Impact Factor
  • K Komukai, E Tanaka, S Kurihara
    [Show abstract] [Hide abstract]
    ABSTRACT: Contraction of cardiac muscle is regulated by intracellular Ca2+ concentration ([Ca2+]i) change. The Ca2+ increased by the action potential is removed by Ca2+ removal mechanisms (sarcoplasmic reticulum, Na-Ca exchanger and Ca pump of the surface membrane) and is also bound to troponin. However, under some specific conditions which induced an overload of Ca2+, oscillatory changes in [Ca2+]i, which are considered to be due to regenerative Ca2+ release from the sarcoplasmic reticulum, appear. In Ca2+ overload, a transient increase in [Ca2+]i is observed after the falling phase of the Ca2+ transient which is induced by electrical stimulation. In accordance with the transient increase in [Ca2+¿i, the membrane transiently depolarizes (delayed after-depolarization). This membrane depolarization is considered to be due to the inward currents through the Na-Ca exchanger and non-specific cation channels. If the depolarization is large enough to reach the threshold, the action potentials are triggered (triggered activity). Thus, an increase in [Ca2+]i is one of possible factors in triggering of arrhythmia.
    Nippon rinsho. Japanese journal of clinical medicine 09/1996; 54(8):2045-9.
  • [Show abstract] [Hide abstract]
    ABSTRACT: A time-of-flight (TOF) multi-probe system has been developed to measure the distribution of positron-emitting tracers in the body. The system uses 16 (a pair of 8) detector probes, each of which is composed of a truncated pyramid BaF<sub>2</sub> crystal and a 26 mm diameter photomultiplier tube (Hamamatsu R5320). The average coincidence time resolution for possible 64 coincidence pairs is 180 ps FWHM, which corresponds to 2.7 cm in space. The system performance such as count rate and imaging capabilities were evaluated using phantoms. The results show that a low-cost positron imaging system can be constructed using the TOF detector probes. The system is designed to increase the number of detector probes up to 32 (a pair of 16) for a better imaging capability
    Nuclear Science Symposium and Medical Imaging Conference Record, 1995., 1995 IEEE; 11/1995
  • [Show abstract] [Hide abstract]
    ABSTRACT: We investigated the effects of thapsigargin (TG) (0.1-1 microM) on the relation between intracellular Ca2+ concentration and tension in ferret papillary muscles using aequorin-injected and skinned preparations. Aequorin was injected into the superficial cells of ferret papillary muscles; the Ca2+ signals of aequorin and tension in twitch and those with the application of 15 mM caffeine were simultaneously measured. The alteration of Ca2+ sensitivity of the contractile elements was examined by measuring the pCa-tension relation in Triton-X-treated skinned preparations. TG decreased the peak of the Ca2+ signal accompanied by a prolonged decay time. However, the tension was scarcely altered even at 1 microM TG. TG inhibited the caffeine-induced Ca2+ signal. Prolongation of decay of the Ca2+ signal by TG in twitch was further enhanced by isoprenaline (10 nM). The pCa-tension relation of the skinned preparation was slightly but significantly shifted to the right by TG. The apparent dissociation of the effects of TG on the Ca2+ signal and tension in intact preparations is not a result of alteration of the Ca2+ sensitivity of the myofilaments. The effects of TG in multicellular preparations are probably limited to the outer layer of the preparation. The slower time course of the Ca2+ signal induced by TG is due to the inhibition of Ca2+ uptake by sarcoplasmic reticulum, which is more significantly observed when the intracellular Ca2+ transient is increased by isoprenaline.
    Cardiovascular Research 10/1995; 30(3):357-62. DOI:10.1016/S0008-6363(95)00053-4 · 5.81 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We investigated the effects of a newly synthesized dihydropyridine (DHP) derivative (NZ-105) on intracellular Ca transients and contraction in ferret ventricular muscles, using the aequorin method. Low concentrations of NZ-105 (10(-9)-10(-7) M) showed no significant effects on the light signal of aequorin and tension in twitch. High concentrations of NZ-105 (10(-6)-10(-5) M) inhibited the peaks of the light signal and tension without altering their time courses. The relation between the peaks of the light signal and tension in twitch, measured in solutions with varying Ca2+ concentrations, was shifted to the left by NZ-105. The relation between [Ca2+]i and tension measured in tetanic contraction was also shifted to the left by NZ-105. These results suggest that the inhibitory effect of NZ-105 on contraction in mammalian cardiac muscle is curtailed by an increase in Ca sensitivity of the contractile elements.
    Journal of Cardiovascular Pharmacology 09/1994; 24(2):274-80. DOI:10.1097/00005344-199424020-00012 · 2.11 Impact Factor
  • K Shimizu, N Satoh, H Uchida, E Tanaka
    [Show abstract] [Hide abstract]
    ABSTRACT: We are developing a time-of-flight (TOF) multiprobe imaging system, which is used to determine the distribution of the administered tracer substances labeled with positron emitting nuclides. A prototype system has eight detector probes, each that consists of a BaF<sub>2</sub> scintillator and a fast photomultiplier tube. The system construction is simple compared to positron emission tomographs by virtue of using TOF information of annihilation. We have studied the time resolution for different shapes of BaF<sub>2</sub> scintillators by Monte Carlo simulations and experiments, and found that truncated pyramid shaped crystals provided good time resolution with reasonable sensitivity. Coincidence time resolution of 180 to 200 ps were obtained with 16 combinations of the detectors in the system. An iterative algorithm for image reconstruction using TOF data was proposed. By introducing a proper deblurring algorithm into the image reconstruction process, the spatial resolution can be improved by a factor of two without significant amplification of noise, which corresponds to a spatial resolution of 1.5 cm
    Instrumentation and Measurement Technology Conference, 1994. IMTC/94. Conference Proceedings. 10th Anniversary. Advanced Technologies in I & M., 1994 IEEE; 06/1994
  • Source
    Y Saeki, S Kurihara, K Hongo, E Tanaka
    [Show abstract] [Hide abstract]
    ABSTRACT: 1. To study the effects of mechanical constraints on the calcium (Ca2+) affinity of cardiac troponin C, we analysed the tension and aequorin light (AL, intracellular Ca2+) transients in response to a step length change in aequorin-injected ferret right ventricular papillary muscles. The muscle preparations were continuously activated with ouabain (10(-4) M) (ouabain contracture) or with high frequency stimuli in the presence of ryanodine (5 microM) (tetanic contraction). 2. The tension transient in response to either the release or stretch was oscillatory: tension decreased rapidly during the release and then increased, after which it lapsed into a new steady level in a series of damped oscillations. The opposite was true for the stretch. The oscillatory responses were conspicuous and less damped in ouabain-activated preparations (oscillation frequency of 2.2-2.3 Hz at 22 degrees and 4.5-4.6 Hz at 30 degrees C) and much more damped in ryanodine-treated preparations. 3. The transient AL response was also oscillatory, the time course of which corresponded to that of the transient tension response. Regardless of the difference in the time course of the transients in two different preparations and at two different temperatures, the increase in AL corresponded to the decrease in tension, likewise the decrease in AL to the increase in tension. 4. The mean level of AL after release was lower than the control level present just prior to the release in ouabain-activated preparations, but the AL after release finally returned to the nearly control level in ryanodine-treated preparations. 5. When the ryanodine-treated muscle was further treated with 2,3-butanedione monoxime (BDM) (20 mM), the tetanic tension decreased remarkably without affecting the AL signal. The tension transient of this preparation was quite similar to that of the resting muscle, which changed in a nearly stepwise fashion; AL was hardly affected by step length changes, as in the resting muscle, in spite of the higher AL level. 6. These results suggest that the Ca2+ affinity of cardiac troponin C is increased with an increase in tension (i.e. the cross-bridge attachment) and decreased with a decrease in tension i.e. the cross-bridge detachment), and that the mean [Ca2+]i is lowered by release, at least in a Ca(2+)-overloaded condition, mainly through the sarcoplasmic reticulum.
    The Journal of Physiology 05/1993; 463:291-306. DOI:10.1113/jphysiol.1993.sp019595 · 4.54 Impact Factor
  • Source
    K Hongo, E Tanaka, S Kurihara
    [Show abstract] [Hide abstract]
    ABSTRACT: 1. To clarify the mechanism which regulates the time course of twitch tension when beta- and muscarinic receptors are stimulated, intracellular Ca2+ transients, Ca2+ sensitivity of the contractile element and the cross-bridge cycling rate (CCR) were measured in ferret ventricular muscles. 2. Isoprenaline (Iso; 0.1 microM) increased peaks of Ca2+ transients measured with aequorin and tension, and abbreviated the time courses of both signals. Addition of acetylcholine (ACh; 0.01-1 microM) to the Iso-treated preparation dose dependently decreased the peaks of both signals and restored the time course of Ca2+ transients. However, the time course of tension was not recovered by the addition of ACh, and the relaxation time in particular, was further shortened by ACh. Carbachol (1 microM) applied to the Iso-treated preparation yielded similar results. 3. [Ca2+]i and tension at a quasi-steady level of tetanic contraction, which was produced by ryanodine (5 microM) and repetitive stimulation, were measured and Ca2+ sensitivity of the contractile element was estimated. Iso (0.1 microM) decreased the Ca2+ sensitivity and the addition of ACh (1 microM) completely recovered it to the control level. 4. In order to measure CCR, the perturbation analysis method was applied to steady-state tension of tetanic contraction. The CCR was not altered even when the tetanic tension level was decreased to 50% by decreasing [Ca2+]o. Iso (0.1 microM) slightly decreased the tetanic tension level and increased the CCR from 2.73 to 3.25 Hz. The effect of Iso was observed when the Iso-decreased tension was recovered by an increase in [Ca2+]i. The addition of ACh (1 microM) recovered the CCR which was increased by Iso, to the control level. Atropine (10 microM) blocked the effect of ACh, and carbachol (1 microM) restored the CCR increased by Iso to the control level. 5. The time course of Ca2+ transients, Ca2+ sensitivity and CCR were antagonistically regulated by beta- and muscarinic receptor stimulation, but the time course of tension did not parallel the changes in these parameters. Therefore, these results suggest that the time course of tension, particularly the relaxation time, is not determined by the time course of Ca2+ transients, Ca2+ sensitivity and the CCR, and that other factors might be involved in the regulation of the time course of tension when beta- and muscarinic receptors are stimulated.
    The Journal of Physiology 03/1993; 461(1):167-84. DOI:10.1113/jphysiol.1993.sp019507 · 4.54 Impact Factor
  • Source
    K Hongo, E Tanaka, S Kurihara
    [Show abstract] [Hide abstract]
    ABSTRACT: 1. We investigated the mechanism of signal transduction during the effect of muscarinic receptor stimulation on Ca2+ transients, tension, Ca2+ sensitivity and the cross-bridge cycling rate (CCR). 2. Membrane-permeable derivatives of cyclic GMP (8-bromo-cyclic GMP and dibutyryl cyclic GMP) did not cause any significant changes in the peaks of Ca2+ transients and tension and the time courses of either signal modulated by isoprenaline (Iso) (0.1 microM). 3. Nitroprusside (0.1-1 mM) likewise did not change the peaks or the time courses of Ca2+ transients and tension in the Iso-treated preparations. 4. In papillary muscles excised from ferrets treated with pertussis toxin (islet-activating protein, IAP), which is known to abolish the function of GTP-binding proteins (Gi, Go and Gt), similar changes in Ca2+ transients and tension produced by treatment with Iso (0.1 microM) were noted as in non-IAP-treated preparations. However, no effects of acetylcholine (ACh; 1 microM) on either signal were observed. 5. The relation between [Ca2+]i and tension measured during the steady state of tetanic contraction was shifted to the right by Iso (0.1 microM), and cyclic GMP derivatives (1 mM) did not change the altered relation. In the IAP-treated preparations, ACh (1 microM) did not influence the relation altered by Iso (0.1 microM). 6. Cyclic GMP derivatives (1 mM) did not alter the Iso (0.1 microM)-increased CCR measured by perturbation analysis. ACh (1 microM) did not restore the Iso-increased CCR in the IAP-treated preparations. 7. These results suggest that signal transduction in muscarinic receptor stimulation is primarily mediated by inhibition of adenylate cyclase via IAP-sensitive GTP-binding proteins, and that cyclic GMP does not play an important role in the effect of muscarinic receptor stimulation on Ca2+ transients, tension, Ca2+ sensitivity or CCR.
    The Journal of Physiology 03/1993; 461:185-99. DOI:10.1113/jphysiol.1993.sp019508 · 4.54 Impact Factor
  • Y Saeki, S Kurihara, K Hongo, E Tanaka
    [Show abstract] [Hide abstract]
    ABSTRACT: To elucidate the effects of mechanical constraints on the (Ca2+) affinity of cardiac troponin C, we studied the relationships among the myoplasmic Ca2+ concentration ([Ca2+]i), tension and length in steadily activated intact cardiac muscle. The Ca2+ sensitive photoprotein, aequorin, was micro-injected into cells of ferret right ventricular papillary muscles to monitor the [Ca2+]i. The muscle was then steadily activated with ouabain (10(-4) M)(ouabain contracture) or high frequency stimuli in the presence of ryanodine (5 microM)(tetanic contraction); the tension and aequorin light (AL) transients in response to a step length change were then analyzed. The tension transient response to either the stretch or release in length was oscillatory: tension decreased rapidly during the release and then increased, after which it lapsed into a new steady level in a series of damped oscillations. The opposite was true for the stretch. The oscillatory responses were conspicuous and less damped in the ouabain contracture. The transient AL response was also oscillatory, the time course of which corresponded exactly to that of the tension transient response, though no detectable changes in AL were observed at the initial phase of the stretch response. The increase in AL corresponded exactly to the decrease in tension, likewise the decrease in AL to the increase in tension. The steady level of AL after release was decreased in ouabain contracture, but was increased in tetanic contraction. These results suggest that the Ca2+ affinity of cardiac troponin C is increased with an increase in tension (i.e., the cross-bridge attachment) and decreased with a decrease in tension (i.e., the cross-bridge detachment), and that the myoplasmic calcium concentration is lowered by release, at least in a Ca(2+)-overloaded condition, mainly through the sarcoplasmic reticulum.
    Advances in Experimental Medicine and Biology 02/1993; 332:639-47; discussion 647-8. · 2.01 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In the PET system a block detector, which is a position-sensitive photomultiplier (PMT) tube coupled to four arrays of 1.7-mm-wide BGO crystals, is utilized. Fifteen block detectors are positioned to form a 35-cm-diameter ring, with four BGO arrays coupled to each PMT. This provides four detector rings, giving the system a 7-slice imaging capability. The gantry head tilts up to +/-90 degrees , and is capable of moving up and down by 30 cm. These positioning capabilities allow flexibility and great ease of use in subject positioning. A gantry entrance size of 22 cm in diameter allows studies ranging from rats and mice to primates such as Rhesus and squirrel monkeys. The physical performance of the system has been evaluated.
    IEEE Transactions on Medical Imaging 02/1992; 11(4):577-80. DOI:10.1109/42.192694 · 3.80 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A high-resolution positron emission tomograph (PET) for brain studies has been developed. It consists of five detector rings (240 BGOs/ring). New multisegment photomultiplier tubes (PMTs) were adopted for the system with 5-mm-wide BGOs. The system is designed to examine a patient sitting or lying down on a chair/bed couch. The functions of PMT auto gain control and real-time image display are implemented in the system. The physical performance of the system was evaluated: the spatial resolution is 3.5 mm in the transaxial plane and 5.7 mm in the axial direction, and the total system sensitivity is 109 kcps/μCi/ml for a uniform phantom 20 cm in diameter with a pulse height threshold of 350 keV
    IEEE Transactions on Nuclear Science 05/1990; DOI:10.1109/23.106683 · 1.46 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A simple time-of-flight (TOF) positron imaging method is proposed in which the spatial resolution obtained with TOF information is improved by a novel iterative algorithm. The prototype has a pair of opposed detectors using BaF<sub>2</sub> (2×2×2 cm<sup>3</sup>) and photomultiplier tubes (18.5-mm diameter). The measured TOF resolution full width at half maximum was 330 ps, which corresponds to 5.0 cm of spatial resolution for source localization between the detectors. Eight iterations with the algorithm improve the spatial resolution by a factor of about two for a point source. The algorithm is based on modifications of a Bayesian deconvolution algorithm. For more complex sources, it takes more iterations (e.g. 80); however the algorithm is about five times faster than the original Bayesian algorithm
    IEEE Transactions on Nuclear Science 03/1989; 36(1-36):998 - 1002. DOI:10.1109/23.34592 · 1.46 Impact Factor
  • Kaku igaku. The Japanese journal of nuclear medicine 07/1987; 24(6):797-807.

Publication Stats

516 Citations
154.57 Total Impact Points

Institutions

  • 1992–1995
    • HAMAMATSU Photonics K.K.
      Hamamatu, Shizuoka, Japan
  • 1993
    • Tsurumi University
      • Department of Physiology
      Yokohama, Kanagawa, Japan
  • 1963–1990
    • National Institute of Radiological Sciences
      Tiba, Chiba, Japan
  • 1982
    • Hitachi, Ltd.
      Edo, Tōkyō, Japan