Atsushi Suzuki

A comparative histochemical study of the masseter muscle of the cattle, sheep, swine, dog, guinea pig, and rat

SummaryThe masseter muscles of different mammals were studied by means of histochemical reactions: NADH: Nitro BT oxidoreductase (NADHOX), 3-hydroxybutyrate: NAD+ oxidoreductase (HBOX), glycerol-3-phosphate: menadione oxidoreductase (GPOX), and acid-stable and alkali-stable myosin adenosine triphosphatase (ATPase). The masseter muscles of cattle and sheep consisted only of the fibres that reacted moderately for GPOX and strongly for NADHOX, HBOX, and the acid-stable ATPase. The masseter fibres of rats and guinea pigs reacted uniformly and strongly for GPOX and the alkali-stable ATPase. The fibres of the rats showed a weak to strong reaction for NADHOX and mostly a negative reaction for HBOX, whereas those of the guinea pigs reacted uniformly and strongly for NADHOX and HBOX. The masseter fibres of swine and dogs showed a weak or strong reaction for the alkali-stable and a negative or weak reaction for HBOX. The fibres of the swine were weak to strong in NADHOX activity and those of the dogs uniformly strong; the fibres of the two species gave a moderate to strong reaction for GPOX. The masseter fibres of the ruminant differed from those of the other species in histochemical properties, and appeared to have the histochemical characteristics that meed functional demands for slow, long-term exercise.

Distribution of myofiber types in thigh muscles of chickens

The composition of myofiber types varies within thigh muscles of chickens. The present study was designed to determine whether or not myofiber types were distributed uniformly across the diameter of the thigh muscles of chickens. Cross sections from middle portions of muscles were used histochemically to examine differences in distribution and composition of myofiber types in the muscles. Myofibers that reacted moderately (M) or strongly (S) for myosin adenosine triphosphatase (ATPase) after preincubation at pH 4.3 were classified as type I. Type I myofibers reacted weakly (W), moderately (M), or strongly (S) for ATPase after preincubation at pH 10.6; these type I myofibers were subclassified into four types (ISW, ISM, ISS, and IMM). Myofibers that reacted negatively for acid‐stable ATPase and strongly for alkali‐stable ATPase were classified into two types: type IIA, with strong NADH tetrazolium reductase (NADH‐TR), and type IIB, with weak NADH‐TR activity. The M. pubo‐ischio‐femoralis pars lateralis had numerous type IIA myofibers and very few type ISM myofibers, whereas the pars medialis had many type IMM myofibers and few type ISS and IIA myofibers. The type I group of myofibers did not exceed about 50% in the other muscles, which had one to three types of type ISW, ISM, and ISS myofibers. The Mm. femorotibiales had more type ISW, and ISM myofibers in the deep regions near the femur than in the superficial regions. The M. iliotibialis cranialis, M. iliofibularis, and M. flexor cruris medialis had more type ISW, ISM, or ISS myofibers in the medial regions than in the lateral regions. A few type ISW myofibers were scattered in the cranial part of M. iliotibialis and in the M. ambiens. The M. flexor cruris lateralis pars pelvica had type IIA and IIB myofibers exclusively. All the muscles had type IIA myofibers. Type IIB myofibers existed in the muscles except the M. puboischio‐femoralis. Type IIA and IIB myofibers differed in proportion in different muscles and in their different regions. The type I group of myofibers was generally concentrated more in the deep regions near the femur and in the medial regions than in the superficial and lateral regions of the thigh muscles. The distribution of type IIA myofibers resembled that of type I group. Type IIB myofibers showed a distribution opposite to that of type I group and IIA myofibers. The spatial distribution of myofiber types within individual muscles can account for the various locomotory and postural requirements of the thigh.

Impact of diastolic dysfunction on the outcome of catheter ablation in patients with atrial fibrillation.

OBJECTIVEnTo evaluate the impact of diastolic dysfunction on the outcome of atrial fibrillation (AF) ablation.nnnMETHODSnEighty consecutive patients with drug-refractory symptomatic AF who underwent AF ablation were enrolled (65 males, 58 ± 10 years, 65 paroxysmal AF, 15 persistent AF). All patients underwent extensive pulmonary vein isolation with a double lasso technique using CARTO MERGE. Diastolic dysfunction was defined as a ratio of the mitral inflow early filling velocity to the velocity of the early medial mitral annular ascent of >10. The clinical and echocardiographic data were compared between the patients with and without diastolic dysfunction, and between the patients with and without AF recurrences after the AF ablation.nnnRESULTSnTwenty-nine out of all the patients (36.3%) had diastolic dysfunction. Compared with the patients without diastolic dysfunction, the patients with diastolic dysfunction had higher brain natriuretic peptide (p=0.001) and C-reactive protein (p=0.023) levels, and a larger left atrial diameter (P=0.019). The AF-free rate after a single or repeat AF ablation procedure in the patients with diastolic dysfunction was lower than that in those without diastolic dysfunction (p=0.005 and p=0.013 by the log-rank test, respectively). In the univariate analysis, the patients with persistent AF and diastolic dysfunction were likely to have AF recurrences after a single AF ablation. The multivariate analysis indicated diastolic dysfunction as the only independent predictor of an AF recurrence after a single AF ablation (P=0.023).nnnCONCLUSIONnThe patients with diastolic dysfunction had a worse outcome of the AF ablation not only for a single procedure but also a repeat procedure.

Energy transferring system for totally implantable medical devices using amorphous magnetic fibers

Abstract The transmitting capacity and temperature rise of transcutaneous energy transmitting coils incorporating amorphous magnetic fibers are discussed. A magnetic core with a long, narrow shape (rather than a pot-core) is preferred for implantation inside the body. For the energy transmitting coils, the reduction in temperature rise is the most important problem. Copper loss is a dominant factor in the reduction of the temperature rise. When the diameter of the coils is halved, the copper loss increases fourfold and the temperature rise increases tenfold.

Contributing factors to the apparent clearance of bepridil in patients with paroxysmal or persistent atrial fibrillation: Analysis using population pharmacokinetics

Background: Bepridil is used as an antiarrhythmic drug due to its class I, class III, and class IV electrophysiological properties, but it has serious adverse effects such as QT prolongation and torsade de pointes. Bepridil has complex pharmacokinetic (PK) properties with large interindividual differences in plasma concentrations. The aim of this study was to evaluate the contributing factors to changes in the dose–concentration relationship of bepridil and the risk factors for excessive QT prolongation in patients with paroxysmal or persistent atrial fibrillation (AF). Methods: A population PK analysis was performed by using NONMEM based on 425 concentration points from 76 patients receiving bepridil. A 1-compartment model approximating an intravenous model was used to examine the interindividual variability of the apparent systematic clearance (CL/F) of bepridil. A population PK–pharmacodynamic analysis was performed using the linear regression. Results: Age was a contributing factor to the CL/F of bepridil in AF patients. The QTc interval increased as the area under the plasma bepridil concentration time curve (AUC) increased. The AUC in patients without a bundle branch block, the baseline QT interval, and the existence of structural heart disease in patients with a bundle branch block were explanatory variables of excessive QTc prolongation (QTc > 500 ms) during bepridil therapy. Conclusions: Using population PK methodology, this study showed that age was a contributing factor to the apparent clearance of bepridil in Japanese patients with AF and that excessive QT prolongation might be related to a larger AUC.

Study on Non-contact Heart Beat Measurement Method by Using Depth Sensor

For the purpose of simple observation of the mechanical phenomenon of the heart, we propose a new non-contact heartbeat measurement using a depth sensor. The depth sensor is an image sensor applying infrared light projection, and by using this sensor it is possible to calculate the three dimensional shape of the chest. In addition, it is possible to measure minute displacement appearing on the body surface by heartbeat. By visualizing the distribution of shape change using computer graphics, visualization of the heart beat is realized. Since the method is non-contact measurement, it does not prevent simultaneous measurement with the electrocardiogram. Therefore, it can be expected to be used as a means for simultaneously observing mechanical and electric phenomena of the heart. Simultaneous measurement using the method and electrocardiogram was performed. As a result of the measurement of three subjects (two males in 20 s and one male in 40 s), it was confirmed that the peak interval of the waveforms obtained by the two methods shows high consistency. The difference between the two peak intervals was less than 0.04 s. In the measurement, subjects stopped respiration, by applying the filtering process, it is also possible to detect the heartbeat waveform during breathing. During respiration, fluctuations are included in the measured waveform. In the simultaneous measurement of the two methods, the difference in the peak intervals is less than 0.05 s. This value is slightly larger than when breathing is stopped. In addition, as a result of the visualization of heart beat, the phase of vibrations by the heartbeat is different at each position on the chest surface. Specifically, a phase lag occurred upward direction from the abdominal, and it is visible by animation. This result suggests that the observation of the mechanical phenomenon of the heart may be realized by the method.

Effects of nutrient enrichment, irradiance control, and boiling on the color of the brown alga Undaria pinnatifida

The color of Undaria pinnatifida after boiling is an important factor determining its marketable value. Our previous study showed that decreased nutrients and elevated irradiance resulted in increases of lightness and yellowness (i.e., discoloration) of this alga. However, little is known about the optimal levels of nutrients and irradiance required to decrease these color values and the combined effects of these factors and boiling. We conducted two culture experiments to test the effects of nutrients (non-enriched and 1.25, 5, and 25% PESI enriched treatments), irradiance (0, 10, 30, and 180xa0µmolxa0m−2xa0s−1), and boiling on lightness L*, redness a*, and yellowness b* of this alga. L* and b* did not differ between non-enriched and 1.25–5% PESI treatments, but were lower in the 25% PESI treatment. L* and b* were lowest at 0–10xa0µmolxa0m−2xa0s−1, although negative growth occurred at 0xa0µmolxa0m−2xa0s−1. Decreased irradiance had a positive or little effect on a* before boiling, but had a negative effect after boiling. These results suggest that around 25% PESI and 10xa0µmolxa0m−2xa0s−1 were the optimal levels to decrease the three color values of this species after boiling.