Biomedical subjects

T Fukunaga

Publications and source records attributed to T Fukunaga.

At least 55 records · Page 3Linked to original sources

PubMed2001

A new polymorph of barium chloroanilate trihydrate.

Single crystals of a new polymorph of the title compound, barium(II) 3,6-dichloro-2,5-dihydroxy-1,4-benzoquinone trihydrate, Ba2+.C6Cl2O4(2-).3H2O, have been grown in sodium metasilicate gel. Each Ba2+ cation is coordinated by eight O atoms. The Ba2+ cations are bridged by an O atom of a ligand around the centre of symmetry at Wyckoff position 4a and by the O atom of a water molecule around the centre of symmetry at Wyckoff position 4b, forming a sheet parallel to the (100) plane. Loose contacts are found around one of the water molecules, as observed in the Cmca form.

Journal Article↗

PubMed2001

Influence of static stretching on viscoelastic properties of human tendon structures in vivo.

The purpose of this study was to investigate the influences of static stretching on the viscoelastic properties of human tendon structures in vivo. Seven male subjects performed static stretching in which the ankle was passively flexed to 35 degrees of dorsiflexion and remained stationary for 10 min. Before and after the stretching, the elongation of the tendon and aponeurosis of medial gastrocnemius muscle (MG) was directly measured by ultrasonography while the subjects performed ramp isometric plantar flexion up to the maximum voluntary contraction (MVC), followed by a ramp relaxation. The relationship between the estimated muscle force (Fm) of MG and tendon elongation (L) during the ascending phase was fitted 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. Stretching produced no significant change in MVC but significantly decreased stiffness and hysteresis from 22.9 +/- 5.8 to 20.6 +/- 4.6 N/mm and from 20.6 +/- 8.8 to 13.5 +/- 7.6%, respectively. The present results suggest that stretching decreased the viscosity of tendon structures but increased the elasticity.

Adult↗

PubMed2001

Behavior of fascicles and tendinous structures of human gastrocnemius during vertical jumping.

Behavior of fascicles and tendinous structures of human gastrocnemius medialis (MG) was determined by use of ultrasonography in vivo during jumping. Eight male subjects jumped vertically without countermovement (squat jump, SQJ). Simultaneously, kinematics, kinetics, and electromyography from lower leg muscles were recorded during SQJ. During phase I (-350 to -100 ms before toe-off), muscle-tendon complex (MTC) length was almost constant. Fascicles, however, shortened by 26%, and tendinous structures were stretched by 6%, storing elastic energy of 4.9 J during phase I. During phase II (-100 ms to toe-off), although fascicles generated force quasi-isometrically, MTC shortened rapidly by 5.3%, releasing prestored elastic energy with a higher peak positive power than that of fascicles. Also, the compliance of tendinous structures in vivo was somewhat higher than that of external tendon used in the simulation studies. The results demonstrate that the compliance of tendinous structures, together with no yielding of muscle fibers, allows MTC to effectively generate relatively large power at a high joint angular velocity region during the last part of push-off.

Adult↗

PubMed2001

Mechanical properties of tendon and aponeurosis of human gastrocnemius muscle in vivo.

Load-strain characteristics of tendinous tissues (Achilles tendon and aponeurosis) were determined in vivo for human medial gastrocnemius (MG) muscle. Seven male subjects exerted isometric plantar flexion torque while the elongation of tendinous tissues of MG was determined from the tendinous movements by using ultrasonography. The maximal strain of the Achilles tendon and aponeurosis, estimated separately from the elongation data, was 5.1 +/- 1.1 and 5.9 +/- 1.6%, respectively. There was no significant difference in strain between the Achilles tendon and aponeurosis. In addition, no significant difference in strain was observed between the proximal and distal regions of the aponeurosis. The results indicate that tendinous tissues of the MG are homogeneously stretched along their lengths by muscle contraction, which has functional implications for the operation of the human MG muscle-tendon unit in vivo.

Achilles Tendon↗

PubMed2001

Effects of isometric training on the elasticity of human tendon structures in vivo.

The present study aimed to investigate the effect of isometric training on the elasticity of human tendon structures. Eight subjects completed 12 wk (4 days/wk) of isometric training that consisted of unilateral knee extension at 70% of maximal voluntary contraction (MVC) for 20 s per set (4 sets/day). Before and after training, the elongation of the tendon structures in the vastus lateralis muscle was directly measured using ultrasonography while the subjects performed ramp isometric knee extension up to MVC. The relationship between the estimated muscle force and tendon elongation (L) was fitted to a linear regression, the slope of which was defined as stiffness of the tendon structures. The training increased significantly the volume (7.6+/-4.3%) and MVC torque (33.9+/-14.4%) of quadriceps femoris muscle. The L values at force production levels beyond 550 N were significantly shorter after training. The stiffness increased significantly from 67.5+/-21.3 to 106.2+/-33.4 N/mm. Furthermore, the training significantly increased the rate of torque development (35.8 +/- 20.4%) and decreased electromechanical delay (-18.4+/-3.8%). Thus the present results indicate that isometric training increases the stiffness and Young's modulus of human tendon structures as well as muscle strength and size. This change in the tendon structures would be assumed to be an advantage for increasing the rate of torque development and shortening the electromechanical delay.

Adult↗

PubMed2001

Influences of repetitive muscle contractions with different modes on tendon elasticity in vivo.

The present study aimed to investigate the effects of repetitive muscle contractions on the elasticity of human tendon structures in vivo. Before and after each endurance test, the elongation of the tendon and aponeurosis of vastus lateralis muscle (L) was directly measured by ultrasonography while the subjects performed ramp isometric knee extension up to maximal voluntary isometric contraction (MVC). Six male subjects performed muscle endurance tests that consisted of knee extension tasks with four different contraction modes: 1) 50 repetitions of maximal voluntary eccentric action for 3 s with 3 s of relaxation (ET1), 2) three sets of 50 repetitions of MVC for 1 s with 3 s of relaxation (ET2), 3) 50 repetitions of MVC for 3 s with 3 s of relaxation (ET3), and 4) 50 repetitions of 50% MVC for 6 s with 6 s of relaxation (ET4). In ET1 and ET2, there were no significant differences in L values at any force production levels between before and after endurance tests. In the cases of ET3 and ET4, however, the extent of elongation after the completion of the tests tended to be greater. The L values above 330 N in ET3 and 440 N in ET4, respectively, were significantly greater after endurance tests than before. These results suggested that the repeated longer duration contractions would make the tendon structures more compliant and that the changes in the elasticity might be not be affected by either muscle action mode or force production level but by the duration of action.

Adult↗

PubMed2001

Validity of estimating limb muscle volume by bioelectrical impedance.

The present study aimed to investigate the validity of estimating muscle volume by bioelectrical impedance analysis. Bioelectrical impedance and series cross-sectional images of the forearm, upper arm, lower leg, and thigh on the right side were determined in 22 healthy young adult men using a specially designed bioelectrical impedance acquisition system and magnetic resonance imaging (MRI) method, respectively. The impedance index (L(2)/Z) for every segment, calculated as the ratio of segment length squared to the impedance, was significantly correlated to the muscle volume measured by MRI, with r = 0.902-0.976 (P < 0.05). In these relationships, the SE of estimation was 38.4 cm(3) for the forearm, 40.9 cm(3) for the upper arm, 107.2 cm(3) for the lower leg, and 362.3 cm(3) for the thigh. Moreover, isometric torque developed in elbow flexion or extension and knee flexion or extension was significantly correlated to the L(2)/Z values of the upper arm and thigh, respectively, with correlation coefficients of 0.770-0.937 (P < 0.05), which differed insignificantly from those (0.799-0.958; P < 0.05) in the corresponding relationships with the muscle volume measured by MRI of elbow flexors or extensors and knee flexors or extensors. Thus the present study indicates that bioelectrical impedance analysis may be useful to predict the muscle volume and to investigate possible relations between muscle size and strength capability in a limited segment of the upper and lower limbs.

Adult↗

PubMed2001

Muscle fiber and tendon length changes in the human vastus lateralis during slow pedaling.

Muscle fascicle lengths of vastus lateralis (VL) muscle were measured in five healthy men during slow pedaling to investigate the interaction between muscle fibers and tendon. Subjects cycled at a pedaling rate of 40 rpm (98 W). During exercise, fascicle lengths changed from 91 +/- 7 (SE) to 127 +/- 5 mm. It was suggested that fascicles were on the descending limb of their force-length relationship. The average shortening velocity of fascicle was greater than that of muscle-tendon complex in the first half of the knee extension phase and was less in the second half. The maximum shortening velocity of fascicle in the knee extension phase was less than that of muscle-tendon complex by 22 +/- 9%. These discrepancies in velocities were mainly caused by the elongation of the tendinous tissue. It was suggested that the elasticity of VL tendinous tissue enabled VL fascicles to develop force at closer length to their optimal length and kept the maximum shortening velocity of VL fascicles low during slow pedaling.

Adult↗

PubMed2001

Mechanical stimulation induces CTGF expression in rat osteocytes.

Connective tissue growth factor (CTGF), which is encoded by an immediate early gene and a member of the CCN family, has been shown to be expressed in osteoblasts, fibroblasts, and chondrocytes. Although CTGF is expressed in bone and cartilage tissues, we tested the hypothesis that CTGF is regulated in mechanotransduction. In the alveolar bone during experimental tooth movement, CTGF mRNA was expressed in osteoblasts and in osteocytes localized around the periodontal ligament under control conditions. Interestingly, 12 hrs after the start of experimental tooth movement, the expression of CTGF mRNA in osteocytes and osteoblasts became more intense around the periodontal ligament, and the intense expression of CTGF extended to osteocytes situated deep in alveolar bone matrix apart from periodontal ligament in both tension and compression sides. Our present findings indicate that CTGF could play a role in regulation of osteocyte function during the mechanical stimulation of bone.

Alveolar Process↗

PubMed2001

Activation of the bulbospinal serotonergic system during experimental tooth movement in the rat.

Experimental tooth movement is known to induce characteristic delayed and continuous nociception. Nociceptive somatic stimuli activate endogenous pain control systems such as descending monoaminergic pathways, which modulate the transmission of ascending sensory messages. To test the hypothesis that bulbospinal serotonergic pathways modulate subchronic nociception, we assayed the medulla at the level of the subnucleus caudalis and peri-aqueductal grey by high-performance liquid chromatography with electrochemical detection for the serotonin (5-hydroxytryptamine, 5-HT) and its metabolite (5-hydroxyindoleacetic acid, 5-HIAA) 24 hrs after the onset of experimental tooth movement. Experimental tooth movement significantly increased 5-HT and 5-HIAA levels, and 5-HIAA/5-HT, an index of serotonin turnover, in the medulla, and 5-HIAA level and 5-HIAA/5-HT in the peri-aqueductal grey, indicating that nociception induced by experimental tooth movement activates the bulbospinal serotonergic pathway.

Animals↗

PubMed2001

Acute necrotizing eosinophilic myocarditis successfully treated by high dose methylprednisolone.

Acute necrotizing eosinophilic myocarditis is the most severe form of eosinophilic myocarditis, or hypersensitivity myocarditis, and is characterized by rapidly progressive congestive heart failure followed by fulminant clinical deterioration that is nearly always fatal. A 55-year-old previously healthy patient with acute necrotizing eosinophilic myocarditis was diagnosed by early myocardial biopsy and successfully treated with corticosteroids. Throughout his hospitalization, the eosinophil count in the peripheral blood remained normal (56-201/mm3). Early stage corticosteroid therapy can have dramatic effects in acute necrotizing eosinophilic myocarditis and early diagnosis by endomyocardial biopsy is recommended.

Acute Disease↗

PubMed2001

[Anesthetic management for the correction of pectus excavatum using pectus bar under video-assistance].

We report anesthetic management for a child undergoing Nuss operation, a minimally invasive operation which requires neither cartilage incision nor its resection for correction of pectus excavatum. The patient was a 7-year-old boy with the funnel index 5 and the mediastinal shift to the left. General anesthesia with endotracheal intubation was induced and maintained with nitrous oxide, sevoflurane and fentanyl. Thoracic epidural anesthesia was used with 0.125% bupivacaine to supplement analgesia. When the curved bar was passed under the sternum with the aid of an endoscope, sinus tachycardia occurred and continued for 5 minutes but subsided without medication. Otherwise operative course was uneventful with negligible blood loss. After surgery, the patient was kept at bed rest for 2 days, receiving epidural patient-controlled analgesia combined with sedation with midazolam with good results. He was allowed to sit 3 days, to walk 5 days and discharged 10 days postoperatively.

Analgesia, Patient-Controlled↗

PubMed2001

Strength capabilities of knee extensor muscles in junior speed skaters.

BACKGROUND: The present study aimed to investigate the gender- and age-related profiles of junior speed skaters in strength capabilities during both single and repetitive maximal contractions. METHODS: The subjects were 19 male (age = 17.1 +/- 0.2 years, X +/- SE) and 13 female skaters (16.9 +/- 0.2 years). Isokinetic knee extension torque (T) developed concentrically in a single contraction at three constant velocities of 1.05, 3.14 and 5.24 rad/sec and 50 repetitive maximal contractions at 3.14 rad/sec was measured using an isokinetic dynamometer. In addition, a B-mode ultrasound apparatus was used to determine the cross-sectional area (CSA) of the quadriceps femoris muscle at mid-thigh. RESULTS: For the junior skaters, T values at three velocities of 1.05, 3.14 and 5.24 rad/sec and the mean value of isokinetic torque (MT) for every five consecutive trials in the first 25 maximal contractions were similar in both genders when they were expressed relative to the product of the cross-sectional area (CSA) of the quadriceps femoris muscle and lower limb length, T/CSAL and MT/CSAL, respectively. However, the males showed significantly higher MT/CSAL values than the females in the last 25 repetitions of the endurance test. In the comparisons between junior and reference senior skaters, T/CSAL for both genders and MT/CSAL for the females showed little age-related difference. For the males, however, MT/CSAL values in the first 15 repetitions of the endurance test were significantly lower in the junior skaters than in the senior ones. CONCLUSIONS: The present results indicate that the strength capabilities of junior speed skaters in a single maximal contraction will be similar in both genders when the difference in muscle size is normalized. However, the junior male skaters may be less fatiguable than the junior female ones in repetitive maximal contractions. Moreover, the comparison between junior and senior skaters suggests that, in postadolescence, males might be more trainable than females to improve torque output during short-term repetitive maximal contractions beyond that achieved during adolescence.

Adolescent↗

PubMed2001

Clinical manifestations of influenza a myocarditis during the influenza epidemic of winter 1998-1999.

OBJECTIVES: The clinical features of myocarditis that developed during the influenza epidemic of winter 1998-1999 were investigated to emphasize the need for medical attention to this disease. METHODS: Nine patients were treated under diagnoses of acute myocarditis during the winter of 1998-1999. Five (two males and three females, mean age 52 +/- 18 years) were examined with myocarditis associated with influenza A. The diagnosis of influenza A myocarditis was based on electrocardiographic and echocardiographic abnormalities, increased creatine kinase levels and at least a four-fold increase in influenza A virus titers using paired sera. RESULTS: All patients had preceding flu-like symptoms and fever. Cardiac involvement developed between 4 and 7 days after the onset of influenza symptoms. Dyspnea progressively worsened in three patients, one went into shock and one had persistent fever, cough and mild dyspnea without apparent cardiac symptoms. Three patients had ST elevation associated with Q waves and one had complete left bundle branch block. The creatine kinase levels were abnormally increased and global wall motion of the left ventricle on echocardiography was decreased in all patients. Two patients had diagnoses of fulminant myocarditis. One patient died of pneumonia following cerebral infarction, but the left ventricular dysfunction normalized in the remaining four patients. CONCLUSIONS: Cardiac involvement occurred between 4 and 7 days after the onset of influenza symptoms, and worsening dyspnea was the most common symptom. Electrocardiography, echocardiography and creatine kinase levels should be checked to determine the potential for cardiac involvement when patients present with suspected influenza associated with worsening dyspnea or prolonged weakness. Increasing the awareness of influenza myocarditis may help in the earlier identification and treatment of this disease during influenza epidemics.

Adult↗

PubMed2001

Electroencephalogram spectral characteristics after alcohol ingestion in Japanese men with aldehyde dehydrogenase-2 genetic variations: comparison with peripheral changes.

BACKGROUND: Electroencephalographic (EEG) activity induced by alcohol ingestion may be influenced by individual differences in alcohol metabolism. Specifically, an absence of the low Km isozyme of aldehyde dehydrogenase (ALDH), found in many Asians, may be related to alterations of EEGs. METHODS: EEG power spectral changes induced by 0.4 ml/kg of alcohol ingestion were compared in two groups of Japanese subjects: NN (ALDH2*1/1, n = 19) and ND (ALDH2*2/1, n = 12). Peripheral changes in heart rate and facial skin temperature were evaluated after the same treatment. Blood ethanol, acetaldehyde, and catecholamine levels were determined to evaluate mediation of the ethanol metabolite, acetaldehyde, and its indirect action on EEGs through the effects on peripheral systems. RESULTS: As expected, blood acetaldehyde was about 10-fold higher in the ND subjects compared with the NN subjects during the postingestion period. Ethanol produced characteristic EEG changes during and after ingestion. The ND subjects, however, displayed brief periods of decrease in slow alpha immediately after alcohol ingestion and showed no long-term EEG changes. The EEG changes were parallel to peripheral changes. CONCLUSIONS: The lack of increased EEG power in the ND subjects may be partly mediated by a direct action of the high concentration of acetaldehyde in the central nervous system that penetrates from the peripheral blood. In addition to this direct action of acetaldehyde, an indirect action, such as feedback from peripheral changes, might prevent the characteristic increase in alpha and beta power observed in the NN subjects.

Acetaldehyde↗

PubMed2001

Reduced prevalence of serum antibodies against adeno-associated virus type 2 in patients with adult T-cell leukaemia lymphoma.

Seroepidemiological studies have shown previously that cancer patients are less likely to have antibodies against the tumour suppressive adeno-associated virus (AAV) than control groups. To examine the influence of AAV infection on the development of adult T-cell leukaemia lymphoma (ATLL), an endemic disease in Southern Japan that is caused by infection with the human T-cell leukaemia virus type 1 (HTLV-I), the prevalence of serum antibodies to AAV type 2 (AAV-2) was tested in healthy HTLV-I carriers (n = 39) and patients with ATLL (n = 31). The results showed a significant difference in AAV-2 seropositivity between the two groups: Only 29% of the ATLL patients had IgG antibodies against AAV-2, whereas 84.6% of the healthy HTLV-I carriers were seropositive. Analysis of total serum IgG and antibodies against the Epstein-Barr virus (EBV) EBNA1 antigen showed that the lack of AAV antibodies in patients was not due to an ATLL-associated immune deficiency. The lower level of AAV-2 seropositivity in ATLL-patients may indicate that AAV-2 antibody-positive HTLV-I carriers might be less likely to develop ATLL or that loss of AAV-2 antibodies may parallel the development of disease.

Antibodies, Viral↗

PubMed2000

Recruitment plasticity of neuromuscular compartments in exercised tibialis anterior using echo-planar magnetic resonance imaging in humans.

We investigated the recruitment plasticity of the superficial tibialis anterior (TA-s) and deep tibialis anterior (TA-d) regions of neuromuscular compartments (NMCs) in the m. tibialis anterior (TA) during exercise using echo-planar imaging (EPI). Six healthy men performed dorsiflexion exercise at 60% of maximum voluntary contraction at a frequency of 10 contractions/min inside the magnetic resonance imaging. Transaxial EPIs of the right leg were acquired every 6 s at rest (0.5 min), during exercise (2.5 min) and recovery (5 min). In TA-s, significantly higher signal intensities (SIs) were shown than those in TA-d from immediately after starting the exercise to recovery. It has been demonstrated that SI reflects the degree of recruitment in the activated muscle, thus our result suggest that preferential firing of motor neurons in the superficial region of the NMC occurs during exercise in human TA muscle.

Adult↗

PubMed2000

Medullary monoamine levels during experimental tooth movement.

We investigated possible influence of nociception induced by experimental tooth movement on the medullary monoaminergic inhibitory systems. Forty-eight hours after the start of the experimental tooth movement, significant increases in dorsal serotonin (5-HT), dopamine (DA), norepinephrine (NE), 5-hydroxyindoleacetic acid (5-HIAA), and dihydroxyphenylacetic acid (DOPAC) levels were detected with ipsilateral dominance. These results suggest that the nociception induced by experimental tooth movement might be under modulation of serotonergic, noradrenergic, and dopaminergic systems.

3,4-Dihydroxyphenylacetic Acid↗