Biomedical subjects

T Fukunaga

Publications and source records attributed to T Fukunaga.

At least 37 records · Page 2Linked to original sources

PubMed2002

Effects of transient muscle contractions and stretching on the tendon structures in vivo.

This study compared the effects of static stretching (ST) and repeated muscle contractions (CON) on the viscoelastic properties of tendon structures in vivo. Eight male subjects performed ST (passively flexed to 35 of dorsiflexion) for 5 min and 50 repetitions of isometric maximum voluntary contraction (MVC) for 3 s each with 3 s relaxation. Before and after each task, the elongation of the tendon and aponeurosis of the medial gastrocnemius muscle (MG) was directly measured by ultrasonography, while the subjects performed ramp isometric plantar flexion up to MVC, followed by a ramp relaxation. The relationship between the estimated muscle force (Fm) and tendon elongation (L) during the ascending phase was applied to a linear regression, the slope of which was defined as stiffness of the tendon structures. The percentage of the area within the Fm-L loop to the area beneath the curve during the ascending phase was calculated as an index representing hysteresis. The ST protocol significantly decreased the stiffness (-8%) and hysteresis (29%)., respectively. In contrast, the CON protocol significantly decreased the stiffness, but not the hysteresis. These results suggested that the stretching and repeated contractions would make the tendon structures more complaint, and further decreased the hysteresis of the tendon structures.

Adult↗

PubMed2002

Feasibility of myocardial dual-isotope perfusion imaging combined with gated single photon emission tomography for assessing coronary artery disease.

The clinical feasibility of both dual-isotope single photon emission tomography (SPET) and gated SPET have been described. The present study evaluates the feasibility of combining gated SPET with exercise 201Tl/rest 99mTc-tetrofosmin dual-isotope SPET corrected for scatter. Ninety-one patients with known or suspected coronary artery disease underwent cardiac catheterization and coronary angiography. Twenty-nine of them underwent exercise 201Tl/rest 99mTc-tetrofosmin dual-isotope SPET with a second 201Tl injection 3 h after the initial 201Tl injection (protocol 1). We then segregated a Bull's eye polar map into three coronary artery territories and quantified the relative regional uptake. The remaining 62 patients underwent exercise 201Tl/rest 99mTc-tetrofosmin dual-isotope SPET combined with gated SPET. We visually evaluated exercise and rest images from the three coronary artery territories. Left ventricular (LV) function was assessed globally by means of the LV ejection fraction and regionally by means of visual scoring analysis, compared with left ventriculography (LVG). The correlation between rest 99mTc-tetrofosmin and 201Tl reinjection images in 87 areas of coronary artery territory (r=0.89, P<0.01) and in 13 infarcted areas (r =0.94, P<0.01) was very close in protocol 1. The overall values for vessel-related sensitivity, specificity and accuracy were 88%, 79% and 82%, respectively, in protocol 2. The correlation between gated SPET and LVG was significant and linear with respect to the LV ejection fraction (r=0.77, P<0.01). The wall motion score from visual evaluation in gated SPET revealed a close overall agreement with LVG (concordance rate, 88%; kappa, 0.670). Exercise 201Tl/rest 99mTc-tetrofosmin dual-isotope SPET with scatter correction for assessing the coronary artery disease offers excellent diagnostic accuracy and the additional gated SPET provides useful information about LV function similar to that for LVG. This sequential protocol requires only 2 h to generate much useful clinical information.

Aged↗

PubMed2001

Ammonium hydrogen tartronate at 240 and 20 K.

The low-temperature structure determination of the title compound, alternatively called ammonium hydrogen hydroxypropanedioate, NH(4)(+) x C(3)H(3)O(5)(-), has revealed that the H atom involved in a very short asymmetric O--H...O hydrogen bond [O...O = 2.448 (2) A at 240 K and 2.4393 (10) A at 20 K] is disordered.

Journal Article↗

PubMed2001

Effects of different duration isometric contractions on tendon elasticity in human quadriceps muscles.

1. The present study aimed to investigate the influence of isometric training protocols with long- and short-duration contractions on the elasticity of human tendon structures in vivo. The elasticity was assessed through in vivo determination of the elongation (L) of the tendons and aponeuroses using ultrasonography, while the subjects performed ramp isometric exercise up to maximum voluntary contraction (MVC). 2. Eight young males completed 12 weeks (4 days per week) of a unilateral isometric training programme on knee extensors, which consisted of two different combinations of contraction and relaxation times at 70 % MVC: one leg was trained using a short-duration protocol (3 sets of 50 repetitions of contraction for 1 s and relaxation for 2 s), and the other leg was trained using a long-duration protocol (4 sets of a combination of contraction for 20 s and relaxation for 1 min). The training volume per session, expressed as the integrated torque, was the same for the two protocols. 3. Both protocols resulted in a significant increase in MVC: 31.8 +/- 17.2 % for the short-duration protocol and 33.9 +/- 14.4 % for the long-duration protocol. Moreover, the training produced significant increases in the muscle volume of the constituents of the quadriceps femoris, with similar relative gains for the two protocols: 7.4 +/- 3.9 % for the short-duration protocol and 7.6 +/- 4.3 % for the long-duration protocol. 4. The short-duration protocol produced no significant change in L values at any of the force production levels. For the long-duration protocol, however, the L values above 550 N were significantly shorter after training. Analysis revealed that the group x test time interaction effect on tendon stiffness was significant. Stiffness increased significantly for the long-duration protocol, but not for the short-duration protocol. 5. The present study demonstrates a greater increase in stiffness of human tendon structures following isometric training using longer duration contractions compared to shorter contractions. This suggests that the changes in the elasticity of the tendon structures after resistance training may be affected by the duration of muscle contraction.

Adult↗

PubMed2001

Hydrogen-bonded complexes of 2-pyridone with centrosymmetric and non-centrosymmetric dicarboxylic acids.

2-Pyridone (2-oxopyrimidine) forms hydrogen-bonded complexes with dicarboxylic acids, the molar ratio of 2-pyridone/dicarboxylic acid being 2:1 for the complexes with oxalic acid (ethanedioic acid), 2C(5)H(5)NO.C(2)H(2)O(4), (I), and trans-beta-hydromuconic acid (trans-hex-3-enedioic acid), 2C(5)H(5)NO.C(6)H(8)O(4), (II), and 1:1 for the complexes with trans-glutaconic acid (trans-pent-2-enedioic acid), C(5)H(5)NO.C(5)H(6)O(4), (III), and L-tartaric acid (L-2,3-dihydroxybutanedioic acid), C(5)H(5)NO.C(4)H(6)O(6).H(2)O, (IV). Common features in the hydrogen-bonding patterns were found for the centrosymmetric and non-centrosymmetric acids, respectively. The 2-pyridone molecule takes the lactam form in these crystals.

Crystallography, X-Ray↗

PubMed2001

Potassium hydrogen trans-glutaconate monohydrate at 295, 245 and 40 K, and its rubidium analogue at 298 K.

A centrosymmetric and short O-H.O hydrogen bond was found in isomorphic crystals of potassium hydrogen trans-glutaconate monohydrate (potassium hydrogen trans-pent-2-ene-1,5-dioate, K(+).C(5)H(5)O(4)(-).H(2)O), (I), and rubidium hydrogen trans-glutaconate monohydrate (rubidium hydrogen trans-pent-2-ene-1,5-dioate, Rb(+).C(5)H(5)O(4)(-).H(2)O), (II). The O.O distance at room temperature is 2.444 (3) A in (I), and 2.417 (4) A in (II). The O.O distance for (I) showed no significant decrease at low temperatures.

Journal Article↗

PubMed2001

In vivo behaviour of human muscle tendon during walking.

In the present study we investigated in vivo length changes in the fascicles and tendon of the human gastrocnemius medialis (GM) muscle during walking. The experimental protocol involved real-time ultrasound scanning of the GM muscle, recording of the electrical activity of the muscle, measurement of knee- and ankle-joint rotations, and measurement of ground reaction forces in six men during walking at 3 km h(-1) on a treadmill. Fascicular lengths were measured from the sonographs recorded. Musculotendon complex length changes were estimated from anatomical and joint kinematic data. Tendon length changes were obtained combining the musculotendon complex and fascicular length-change data. The fascicles followed a different length-change pattern from those of the musculotendon complex and tendon throughout the step cycle. Two important features emerged: (i) the muscle contracted near-isometrically in the stance phase, with the fascicles operating at ca. 50 mm; and (ii) the tendon stretched by ca. 7 mm during single support, and recoiled in push-off. The behaviour of the muscle in our experiment indicates consumption of minimal metabolic energy for eliciting the contractile forces required to support and displace the body. On the other hand, the spring-like behaviour of the tendon indicates storage and release of elastic-strain energy. Either of the two mechanisms would favour locomotor economy

Adult↗

PubMed2001

Ergometry for estimation of mechanical power output in sprinting in humans using a newly developed self-driven treadmill.

An evaluation of mechanical power during walking and running in humans was undertaken after developing a specially designed running ergometer (RE) in which the subjects gripped the handlebar in front of them keeping both arms straight and in a horizontal position. Ten subjects participated in comparisons of the mean horizontal pushing force (MFam) on the handlebar with the mean horizontal ground reaction force (MFfp) recorded by force platform under the RE during five different constant speeds of walking or running and sprint running with maximal effort. Mechanical power developed during sprint running on the RE was compared with a 50 m sprint. Mean linear velocity (Mv) of the RE belt was recorded by the rotary encoder attached to the axis of the belt. Mean mechanical power calculated from the handlebar setting (MPam = MFam x Mv) was compared to that calculated from force platform recordings (MPfp = MFfp x Mv). A high test-retest reproducibility was observed for both MFfp (r = 0.889) and MFam (r = 0.783). Larger values for the coefficient of variation for MFam (11.3%-15.8%) were observed than for MFfp (3.3%-8.2%). The MPam, which were obtained from five different constant speeds of walking, running and sprint running were closely correlated to those of MPfp (y = 0.98x - 19.10, r = 0.982, P < 0.001). In sprint running, MPam was 521.7 W (7.67 W.kg-1) and was correlated to the 50 m sprint time (r = -0.683, P < 0.01). It is concluded that the newly developed RE was useful in the estimation of mechanical power output during human locomotion such as when walking, jogging and sprinting.

Adult↗

PubMed2001

Is passive stiffness in human muscles related to the elasticity of tendon structures?

The purpose of this study was to examine in vivo whether passive stiffness in human muscles was related to the elasticity of tendon structures and to performance during stretch-shortening cycle exercise. Passive torque of plantar flexor muscles was measured during passive stretch from 90 degrees (anatomical position) to 65 degrees of dorsiflexion at a constant velocity of 5 degrees.s-1. The slope of the linear portion of the passive torque-angle curve during stretching was defined as the passive stiffness of the muscle. The elongation of the tendon and aponeurosis of the medial gastrocnemius muscle (MG) was directly measured using ultrasonography during ramp isometric plantar flexion up to the voluntary maximum. The relationship between the estimated muscle force of MG and tendon elongation was fitted to a linear regression, the slope of which was defined as the stiffness of the tendon. In addition, the dynamic torques during maximal voluntary concentric plantar flexion with and without prior eccentric contraction were determined at a constant velocity of 120 degrees.s-1. There were no significant correlations between passive stiffness and either the tendon stiffness (r = 0.19, P > 0.05) or the relative increase in torque with prior eccentric contraction (r = -0.19, P > 0.05). However, tendon stiffness was negatively correlated to the relative increase in torque output (r = -0.42, P < 0.05). The present results suggested that passive stiffness was independent of the elasticity of tendon structures, and had no favourable effect on the muscle performance during stretch-shortening cycle exercise.

Adult↗

PubMed2001

Effect of local blood circulation and absolute torque on muscle endurance at two different knee-joint angles in humans.

The effects of the local blood circulation and absolute torque on muscle endurance at different knee-joint angles were determined. The rate of muscle deoxygenation (using near-infrared spectroscopy), and the rate of muscle fatigue (using the slope of integrated electromyography, iEMG) were evaluated concurrently. Nine healthy subjects performed submaximal (50% maximal voluntary contraction. MVC) static knee extension at 50 degrees (extended position, EXT) and 90 degrees (flexed position, FLEX) joint angles until the target torque could no longer be maintained: that time was measured as the endurance time. They exercised with the circulation occluded (OCCL), and without (FREE) to study the possible effects of the local circulation. Although MVC torque was independent of joint angle [mean (SD) FLEX 250.6 (51.7) Nm and EXT 246.5 (46.6) N x m], significantly shorter (P<0.01) endurance time in FLEX [FREE 71.1 (10) s and OCCL 63.1 (8.8) s] than at EXT [FREE 115.3 (30) s and OCCL 106.7 (29.1) s] were obtained in both circulatory conditions. The iEMG-time slope was significantly greater in FLEX at the proximal and distal portion (P<0.05) in both circulatory conditions. Muscle deoxygenation rate in OCCL was significantly greater (P<0.05) at FLEX [20.8 (8.0)%] than EXT [10.9 (4.0)%]. The results would suggest that different knee-joint angle affects muscle endurance even if the local circulation is controlled. Circulatory disturbance would further reduce muscle endurance in EXT, but not in FLEX. Because of the greater muscle internal force in FLEX, local blood flow might be already limited even with a free circulation. The greater muscle deoxygenation and muscle fatigability would be related to the shorter muscle endurance in FLEX.

Adult↗

PubMed2001

Kinetics of cytokines and PMN-E in thoracoscopic esophagectomy.

BACKGROUND: Perioperative increases in the levels of cytokines and polymorphonuclear leukocyte elastase (PMN-E) have been shown to be related to degree of surgical trauma. METHODS: We measured the changes in levels of interleukin-6 (IL-6), interleukin-8 (IL-8), and PMN-E in the perioperative period in patients undergoing thoracoscopic esophagectomy (n = 15) and conventional transthoracic esophagectomy (n = 15) for thoracic esophageal cancer. RESULTS: Both IL-6 and IL-8 increased markedly immediately after transthoracic esophagectomy and thereafter, but only a slight increase was observed after the thoracoscopic procedure (IL-6: p = 0.047; IL-8: p = 0.03). A difference was also seen in the pattern of changes in PMN-E. Levels of PMN-E increased immediately after transthoracic esophagectomy and continued to be high up to the 3rd postoperative day, but they remained low after the thoracoscopic procedure and showed no increase (p <lt; 0.01). CONCLUSION: These results suggest that, compared with transthoracic esophagectomy, thoracoscopic esophagectomy results in less production of cytokines and PMN-E and thus causes less surgical trauma.

Cytokines↗

PubMed2001

Medium-chain triglyceride-rich enteral nutrition is more effective than low-fat enteral nutrition in rat colitis, but is equal in enteritis.

BACKGROUND: Although enteral nutrition (EN) therapy for Crohn's disease has been confirmed to be as effective as steroid therapy, the precise mechanism responsible for the effects of EN remains unclear, although some of the therapeutic effects of EN are believed to be due to a low dietary fat content. In order to elucidate the influence of fat in EN, it is important to investigate not only the quantity of fat, but also the source of the fat. METHODS: We compared two enteral nutritional formulae: Elental (Ajinomoto) (elemental diet; ED), which contains only 1.5% fat, provided as long-chain triglycerides (LCT), versus Twinline (Snow Brand Milk Products) (TL), which contains a high percentage of fat (20.4%), provided mainly as medium-chain triglycerides (MCT). These formulae were tested on rat enteritis and rat colitis induced by trinitrobenzene sulfonic acid (TNBS). RESULTS: Both ED and TL reduced the manifestations of enteritis. TL had a stronger anti-inflammatory effect than ED for colitis. TL also had nutritional advantages as compared with ED, as shown by the total serum protein in the TL group being significantly higher than that in the ED group. CONCLUSION: The results indicate that intraluminal MCT is suitable as a fat energy source during intestinal inflammation in rats. We suggest that Twinline may be more useful to improve nutritional status and to reduce the mucosal inflammation in rat colitis, but that Twinline is equal in effect to Elental for rat enteritis.

Animals↗

PubMed2001

Gene and protein expression of brain-derived neurotrophic factor and TrkB in bone and cartilage.

Gene and protein expressions of brain-derived neurotrophic factor (BDNF) and TrkB, the high-affinity receptor of BDNF, were investigated in the femur and mandibular condyle of rats by in situ hybridization and immunohistochemistry. BDNF and TrkB mRNA showed overlapped expression in chondrocytes in proliferating and mature zones of the epiphyseal growth plate cartilage and mandibular condylar cartilage, and in cuboidal-shaped active osteoblasts at the site of endochondral and intramembranous ossification and in trabecular bone. Expression of BDNF protein also showed a similar localization. The present study suggests that BDNF may participate in regulating the development and remodeling of bony tissue in the developing rat.

Animals↗

PubMed2001

Muscle volume is a major determinant of joint torque in humans.

Muscle force (MF) is linearly related to physiological cross-sectional area (CSA), which is obtained from muscle volume (MV) divided by fibre length. Taking into account the fact that joint torque (TQ) is determined by MF multiplied by the moment arm, the maximal TQ would be a function of MV. This proposition was tested in the present study by investigating the relationship between MV and TQ for elbow flexor (EF) and extensor (EE) muscles of 26 males. The MVs of EF and EE were determined from a series of muscle CSA by magnetic resonance imaging (MRI), and pennation angle (theta) and FL by ultrasonography (US). Maximal isometric TQ was measured at right angle of elbow joint for EF and EE. There was a highly significant correlation between MV and TQ both for EF and EE (r=0.95 and 0.96 respectively) compared with that between muscle CSA and TQ, suggesting the dependence of TQ on MV. Furthermore, prediction equations for MV (MVULT) from muscle thickness (MT) measured by US was developed with reference to MVMRI by the MRI on 26 subjects, and the equations were applied to estimate MV of healthy university students (CON; 160 males) and sports athletes (ATH; 99 males). There were significant linear relationships between MVULT and TQ both for EF (r=0.783) and EE (r=0.695) for all subjects (n=259). The MVULT was significantly higher in ATH (by 32% for EF and 33% for EE, respectively) than in CON. Similarly, significantly greater TQ was observed in ATH (by 35% for EF, 37% for EE, respectively). The theta for EE showed no difference between both groups (17.8 degrees for CON and 17.5 degrees for ATH). On the other hand, the TQ to MV ratio were identical for CON and ATH. The results reveal that the muscle volume of the upper arm is a major determinant of joint torque (TQ), regardless of athletic training.

Adult↗

PubMed2001

Neural control: novel evaluation of stretch reflex sensitivity.

We evaluated the stretch reflex activities of the elbow flexor and extensor muscles considering the relationship between the reflex electromyographic (EMG) responses and their corresponding standardized muscle stretch velocities. Specifically, muscular stretch velocity was estimated by using ultrasonograms. Stretch reflex EMG responses were elicited in the biceps brachii, brachioradialis and triceps brachii with a ramp-and-hold rotation at the elbow joint, which consisted of various angular velocities for the extension- or flexion-direction. The whole muscle stretch velocity induced by each ramp-and-hold rotation was calculated on the basis of fibre length changes associated with the elbow joint angle. A linear regression equation was fitted to the relation between the whole muscle stretch velocity and the reflex EMG responses, and the variables from the equation were used to quantify sensitivity of each reflex EMG component. The reflex EMG responses were increased as the ramp-and-hold rotational velocity increased. There were no significant differences in the recorded magnitudes of reflex EMG responses with equivalent joint rotational velocity between the brachioradialis and the triceps brachii medial head. These muscles showed the highest reflex responses in the flexor and extensor muscles, respectively. To the contrary, the reflex EMG response elicited by the standardized muscle stretches was significantly greater in the extensor muscles, indicating a higher reflex sensitivity. This was because of the lower muscle stretch velocity of the triceps brachii with an equivalent elbow joint rotation. The stretch reflex sensitivity in both the elbow flexor and extensor muscles might be regulated so as to make the reflex responses the same when the equivalent joint rotational velocity is applied to these muscles.

Elbow Joint↗

PubMed2001

Inactivity and muscle: effect of resistance training during bed rest on muscle size in the lower limb.

The present study aimed to investigate the effect of dynamic leg press training on the physiological cross-sectional areas (PCSAs) of human lower limb muscles during 20 days of 6 degrees head-down tilt bed rest. Five healthy men comprised the resistance training group (BR-Tr) and data from two previous studies were used to derive a 10-man control group (BR-Cont). The BR-Tr performed two sessions (morning and afternoon session) of dynamic leg press action including knee extension and plantar flexion daily for the bed rest period: (1) three sets of 10 repetitions at 90% of maximum load and (2) 40% of maximum load to exhaustion. The PCSAs of the knee extensor (KE), knee flexor (KF), plantar flexor (PF), and dorsiflexor muscle groups were estimated using serial axial magnetic resonance (MR) images of the right-thigh and leg. After the bed rest period, the BR-Tr showed a significant increase in the PCSA of the KE. Although PCSA of the KF in two groups significantly decreased after bed rest, percentage of change in PCSA of the biceps femoris (long head) and semitendinosus muscles in the BR-Tr, which occupied approximately 70% of the KF, was significantly higher than those in the BR-Cont. Both the BR-Tr and BR-Cont groups showed significant decreases in the PCSA of PF with similar magnitude of 11.6% (P < 0.001) and 11.9% (P < 0.001), respectively. These results suggest that dynamic leg press training during bed rest can prevent deteriorating of the KE and a part of KF, but not the calf muscles.

Adult↗

PubMed2001

Changes in aponeurotic dimensions upon muscle shortening: in vivo observations in man.

Aponeurotic deformation measurements have traditionally been taken by loading dissected muscles; thus the values obtained may not reflect in vivo function. In the present study, we estimated dimensional changes in the central aponeurosis of the intact human tibialis anterior muscle upon loading induced by muscle contraction. Measurements were taken in seven males, and involved real-time ultrasound scanning of the tibialis anterior muscle at 30 degrees of plantarflexion at rest and during isometric dorsiflexion maximum voluntary contraction (MVC). At each contraction state, the length of the aponeurosis, the width along its length, and its area were estimated from sagittal-plane and axial-plane sonographs. In the transition from rest to MVC, the length of the aponeurosis increased by 7% (P < 0.05), its width increased by up to 21 % (P < 0.05), and its area increased by 17% (P < 0.05). These results indicate that the in vivo tibialis anterior aponeurosis behaves as a compliant material upon active muscle shortening. The methodology employed allows cross-sectional and longitudinal design investigations, circumventing the problems associated with epimysial removal under in vitro experimental conditions.

Adult↗

PubMed2001

Functional relevance of human adh polymorphism.

This article represents the proceedings of a symposium at the 2000 ISBRA Meeting in Yokohama, Japan. The chairs were C. J. Peter Eriksson and Tatsushige Fukunaga. The presentations were (1) 4-Methylpyrazole as a tool in the investigation of the role of ADH in the actions of alcohol in humans, by Taisto Sarkola and C. J. Peter Eriksson; (2) ADH2 polymorphism and flushing in Asian populations, by Wei J. Chen, C. C. Chen, J. M. Ju, and Andrew T. A. Cheng; (3) Role of ADH3 genotypes in the acute effects of alcohol in a Finnish population, by Hidetaka Yamamoto, Kathrin Kohlenberg-Müller, and C. J. Peter Eriksson; (4) Clinical characteristics and disease course of alcoholics with different ADH2 genotypes, by Mitsuru Kimura, Masanobu Murayama, Sachio Matsushita, Haruo Kashima, and Susumu Higuchi; (5) ADH2 polymorphism, alcohol drinking, and birth defects, by Lucinda Carr, D. Viljoen, L. Brooke, T. Stewart, T. Foroud, J. Su, and Ting-Kai Li; and (6) ADH genotypes and alcohol use in Europeans, by John B. Whitfield.

Adult↗