Biomedical subjects

T Fukunaga

Publications and source records attributed to T Fukunaga.

At least 73 records · Page 4Linked to original sources

PubMed2000

Fatal acute alcohol intoxication in an ALDH2 heterozygote: a case report.

On an evening in November, a 25-year-old man was found dead in his bedroom. There were many empty snap-out sheets for flunitrazepam tablets in the trash at his bedside. He had been beaten by a gang of young people earlier in the morning of the same day. At the medico-legal autopsy, although there were many bruises and/or abrasions on the whole body, only slight subdural hemorrhage was observed, and none of them was thought to be the cause of death. Flunitrazepam and its metabolites were not detected in his body fluid by gas chromatography-mass spectrometry (GC-MS). Marked lung edema and a severe congestion of organs were observed. His blood alcohol concentration from the femoral vein was 2.00 mg/ml. Fatal cases of acute alcohol intoxication usually have shown higher alcohol concentration (2.25-6.23 mg/ml). Although the genotype of aldehyde dehydrogenase 2 (ALDH2) has not previously been mentioned as a contributing factor in determining the cause of death, in this case the genotype of ALDH2 was ALDH2*1/2 and thus is important. Those who possess the ALDH2*2 gene show high concentrations of acetaldehyde (AcH) at even comparatively lower alcohol levels. Consequently, the cause of death was considered to be acute alcohol intoxication including AcH poisoning.

Acetaldehyde↗

PubMed2000

Validity of bioelectrical impedance and ultrasonographic methods for estimating the muscle volume of the upper arm.

The present study aimed to investigate the validity of bioelectrical impedance and ultrasonographic methods for predicting the muscle volume of the upper arm. Bioelectrical impedance of the right upper arm and the thickness of elbow flexor and extensor muscles were measured from 26 healthy young adult men using a specially designed bioelectrical impedance data acquisition system and brightness-mode ultrasound apparatus, respectively. As reference data, the muscle volume (MV(MRI)) of the right upper arm was determined using a magnetic resonance imaging method. The impedance index was calculated as L2/Z, where L is the upper arm length and Z is the impedance of the shoulder to the elbow. The muscle volume (MV(ULT)) was calculated as pi x (d/2)2 L, where d is muscle thickness. L2/Z and MV(ULT) were significantly correlated with MV(MRI) with correlation coefficients of 0.971 and 0.962, respectively. In these relationships, the standard errors of estimation were 44.2 cm3 (6.3%) for L2/Z and 50.7 cm3 (7.2%) for MV(ULT). There was no significant difference between the absolute errors of muscle volumes estimated by L2/Z and MV(ULT): 36.2 (4.8, SEM) cm3 for L2/Z versus 40.3 (5.8) cm3 for MV(ULT). The present results suggest that both bioelectrical impedance and ultrasonographic methods may be useful for predicting the muscle volume of the upper arm.

Adult↗

PubMed2000

Changes in the elastic properties of tendon structures following 20 days bed-rest in humans.

The purpose of this study was to investigate the effects of 20 days bed-rest on the elastic properties of tendon structures of the human knee extensor muscles in vivo. Six healthy men carried out a 6 degrees head-down bed-rest for 20 days. Muscle volume and maximal voluntary contraction (MVC) torque of the quadriceps femoris muscle significantly decreased by an average of 7.8 (SD 2.7)% and 14.9 (SD 6.9)%, respectively. Before and after bed-rest, the elongation (l) of the tendon and aponeurosis of vastus lateralis muscle was measured directly by ultrasonography, while the subjects performed ramp isometric knee extension up to MVC. The extent of l tended to be greater after bed-rest. The l above 110 N was significantly greater after bed-rest. Furthermore, the mean stiffness after bed-rest [35.5 (SD 7.8) N x mm(-1)] was significantly lower than that before bed-rest [52.6 (SD 19.2) N x mm(-1)]. The rate of torque development significantly reduced after bed-rest by an average of 47%, and the bed-rest induced a lengthening in the electromechanical delay (mean 21%). These results suggest that bed-rest results in a decrease in the stiffness of tendon structures with a reduction of muscle strength and volume. These adaptations of the tendon structures to bed-rest would bring about the changes in electromechanical delay and rate of torque development.

Adult↗

PubMed2000

The use of magnetic resonance images to investigate the influence of recruitment on the relationship between torque and cross-sectional area in human muscle.

The purpose of the present study was to investigate the effect of recruitment on the relationship between peak torque and physiological cross-sectional area (PCSA) in human muscle. A group of 11 healthy men participated in this study. Isokinetic knee extension torques at seven (0, 30, 60, 120, 180, 240, and 300 degrees x s(-1)) velocities were determined. Magnetic resonance imaging (MRI) was performed to calculate PCSA of right quadriceps femoris (QF) muscle. Exercise-induced contrast shifts in spin-spin relaxation time (T2)-weighted MRI were taken at rest and immediately after repetitive knee-extension exercise and T2 of QF were calculated. The MRI pixels with T2 values more than 1 SD greater than the means at rest were considered to represent QF muscle that had contracted. The area of activated PCSA within the total in QF was expressed as percentage activated PCSA and used as an index of muscle recruitment. The PCSA correlated with peak torque at 0 degree x s(-1) (r = 0.615, P<0.05); in contrast, activated PCSA correlated with peak torque at 120 degrees x s(-1) (r = 0.603, P<0.05) and 180 degrees x s(-1) (r = 0.606, P<0.05). Additionally, there was a significant difference in correlation coefficients between the activated PCSA-peak torque relationship and the PCSA-torque relationship (P<0.05). These results suggested that muscle recruitment affects the PCSA-torque relationship.

Adult↗

PubMed2000

Elastic properties of muscle-tendon complex in long-distance runners.

The purpose of this study was to investigate the elastic properties of muscle-tendon complex (MTC) in knee extensor muscles and the capacity for elastic energy utilization in long-distance runners (LDR) by comparing with data obtained from untrained individuals (CON). The elongation (L) of the tendon and aponeurosis of vastus lateralis muscle during isometric knee extension was determined by real-time brightness mode ultrasonography, while the subjects developed a gradually increasing torque from 0 (relaxed) to maximal effort (MVC) within 7 s. In addition, performances in two kinds of maximal vertical jumps, i.e. squatting (SJ) and counter-movement jumps (CMJ), were measured. The relationship between L muscle and force (F) was curvilinear and consisted of an initial region (toe region), characterized by a large increase in L with increasing F, immediately followed by a linear region. The slope of the regression equation for the L-F relationship in the range 50%-100% of MVC was defined as an index of MTC compliance, where the rate of the changes in L to that in muscle F at every 10% of MVC became almost constant. The maximal L (Lmax) and MTC compliance were significantly lower in LDR than in CON: 29.9 (SD 3.9) mm in LDR compared to 33.3 (SD 5.5) mm in CON for Lmax and 1.55 (SD 0.25) x 10(-2) mm.N-1 in LDR compared to 1.88 (SD 0.82) x 10(-2) mm.N-1 in CON for MTC compliance. Also, LDR showed significantly less elastic energy absorption (Ee) than CON, defined as the area below the L-F relationship curve from 0 to 100% of MVC. Not only jump heights but also the differences between the heights in SJ and CMJ, expressed as the percentage of the height in SJ, were significantly lower in LDR than in CON. The augmentation with counter-movement was significantly correlated to either MTC compliance (r = 0.554, P < 0.05) or Ee (r = 0.563, P < 0.05). Thus, the present results would indicate that MTC of vastus lateralis muscle is less compliant and its potential for energy storage during MTS lengthening is lower in LDR than untrained individuals. These elastic profiles of vastus lateralis muscle in LDR may be associated with their lower performances during CMJ.

Adult↗

PubMed2000

Leg-press resistance training during 20 days of 6 degrees head-down-tilt bed rest prevents muscle deconditioning.

The purpose of this study was to investigate the effects of resistance training on the morphological and functional properties of human lower limb muscles during 20 days of 6 degrees head-down-tilt bed rest. Nine men were randomly assigned to the resistance training group (BR-Tr, n = 5) or the non-training, control group (BR-Cont, n = 4). Isometric leg-press exercises were performed: 3 s x 30 repetitions (30 s rest between repetitions) daily for 20 days during the bed-rest period. Serial axial magnetic resonance images were taken from the right thigh and leg muscles, and muscle volume, muscle length, and fibre length were estimated. The physiological cross-sectional areas (PCSAs) of the knee extensor, knee flexor, ankle plantarflexor, and ankle dorsiflexor (tibialis anterior) muscle groups were determined as muscle volume multiplied by the cosine of the angle of fibre pennation divided by fibre length. Maximum voluntary contraction (MVC) during knee extension was measured. No significant changes were observed in the PCSA of the knee extensor muscles in BR-Tr group, whereas the PCSA in the BR-Cont group decreased by 7.8%. The PCSA of the knee flexor and plantarflexor muscles in the BR-Tr group and BR-Cont group significantly decreased after bed rest (knee flexors, 10.2% and 11.5%; plantarflexors, 13.0% and 12.8%, respectively). However, in both groups bed rest had no effect on the muscle volume and PCSA of the tibialis anterior. MVC was maintained by resistance training in the BR-Tr group (decreased by 1%). In contrast, a decline of strength was observed in the BR-Cont group (-16%), but this result was not statistically significant. These results suggest that isometric leg-press training prevents the deconditioning (i.e. atrophy and decline of strength) of the knee extensor muscle group.

Adult↗

PubMed2000

Nonlinear time-course of lumbar muscle fatigue using recurrence quantifications.

Isometric skeletal muscle fatigue is usually assumed to be a linear process based upon the monotonic decrease in spectral frequency of the EMG. Since spectral analysis by fast Fourier transform (FFT) constitutes a linear transformation of the data, the present study was designed to reevaluate the time-course of muscle fatigue with a nonlinear tool, recurrence quantification analysis (RQA). Surface EMG recordings were obtained from the multifidus muscle of 17 human subjects during isometric posture-holding of the upper torso. The process of muscle fatigue was found to be linear for 59% of the subjects by FFT criteria, but nonlinear for 76% by RQA criteria. As a demonstrative control, both slow and fast transients occurring within a nonlinear mathematical process could be accurately depicted by RQA, but not by FFT. It is concluded that assessment of EMG patterns by nonlinear techniques can give insight into the time-course of fatiguing muscles attributed to the summation of several nonlinear and competing processes.

Adult↗

PubMed2000

Adenoid basal carcinoma of the uterine cervix: a case report with ultrastructural findings.

Adenoid basal carcinoma of the uterine cervix is a rare tumor with a favorable prognosis. A case of adenoid basal carcinoma (ABC) of the uterine cervix was studied using light and electron microscopy. The patient was a 74-year-old Japanese woman who had undergone hysterectomy due to cervical intraepithelial neoplasia 3. Incidentally, ABC was found in the resected uterus. The tumor cells made small nests and infiltrated the cervical portion of the uterus. In the nests, glands, cribriform patterns with glandlike structures, and squamous differentiation were seen. Immunohistochemically, the glandlike structures were positive for laminin and type IV collagen. Ultrastructurally, the tumor cells had irregular nuclei, scanty cytoplasm, and cribriform patterns in which glandlike structures were covered with basal lamina. No myoepithelial differentiation of the tumor cells was seen. These findings suggest a similarity between adenoid basal carcinomas and adenoid cystic carcinomas. Furthermore, both tumors are considered to originate in the reserve cells of the uterine cervix. Because their outcomes are different, they should be distinguished from each other.

Aged↗

PubMed2000

In vivo moment arm determination using B-mode ultrasonography.

The tendon excursion of the tibialis anterior (TA) muscle was measured in vivo using B-mode ultrasonography in seven subjects under three force levels (0, 30 and 60% maximal voluntary contraction, MVC). For each force level, the TA moment arm (m) was determined by calculating the derivative of the tendon excursion relative to the ankle angle (a). A dynamometer controlled the ankle angle while force levels were monitored. The parametric model proposed by Miller and Dennis (1996), m = R sin(a + delta), where R is the largest moment arm and delta represents the offset angle of R from 90 degrees, was used in a least-squares fit of the relationship between moment arm and ankle angle. The R values at 0% MVC were significantly smaller than those at 30 and 60% MVC. The values of calculated moment arm at 0% MVC were not considered adequate estimates of the TA moment arm because of the possible confounding effect of the slackness of the relaxed muscle-tendon unit in more dorsiflexed positions. The moment arm values at 30 and 60% MVC were believed to provide reliable estimates of those of TA since the application of tension probably reduced the effects of the slackness of the muscle-tendon unit and tendon elongation on tendon excursion measurement at these force levels. Since the ultrasonographic technique is an in vivo application of the tendon excursion technique and therefore takes the functional meaning into consideration, it can yield more significant moment arms than other in vivo or cadaver techniques.

Adult↗

PubMed2000

Elasticity of tendon structures of the lower limbs in sprinters.

The present study aims to investigate the elasticity of tendon structures of the lower limbs in sprinters and its relation with sprint performance. Subjects were 10 male sprinters and 14 controls whose anthropometric variables and isometric maximum strength were similar. The elongation (L) of the tendon and aponeurosis of vastus lateralis (VL) and medial gastrocnemius muscles (MG) during isometric knee extension and planter flexion, respectively, were determined using a real-time ultrasonic apparatus in vivo, while the subjects developed a gradually increasing torque from zero (relax) to maximal effort (MVC) within 5 s. While sprinters compared with controls showed significantly greater L above 500 N (about 50% of MVC) and higher dL/dF for VL at less than 20% of MVC during knee extension, there were no significant differences between the two groups in L and dL/dF for MG at every 10% of MVC during plantar flexion. Moreover, the average value of dL/dF above 50% of MVC, proposed as the compliance of tendon structures, did not significantly differ between sprinters and controls in either VL or MG. In a regression analysis within sprinters, the compliance of VL was negatively correlated to 100-m sprint time, r=-0.757 (P < 0.05), but that of MG was not, r=0.228 (P > 0.05). Thus the present results indicate that the elasticity of tendon structures of VL and MG at high force production levels, which might be assumed to associate with the storage and subsequent release of energy during exercises involving the stretch-shortening cycle, are similar in both sprinters and controls. For sprinters, however, the tendon structures of VL are more compliant than that for controls at low force production levels, and its elasticity at high force production levels may influence sprint performance.

Adult↗

PubMed2000

In vivo dynamics of human medial gastrocnemius muscle-tendon complex during stretch-shortening cycle exercise.

The purpose of this study was to investigate the dynamics of human muscle-tendon complex (MTC) during stretch-shortening cycle exercises through in vivo observation. A total of seven male subjects performed dorsi flexion followed by plantar flexion at two different frequencies, 0.3 Hz (slow) and 1.0 Hz (fast), in a toe-standing position. The fascicle length (LF) of the medial gastrocnemius muscle during the movements was determined using a real-time ultrasonography in vivo. The LF at the switching phase from dorsi to plantar flexion was significantly shorter in the fast exercise (54.4 +/- 5.5 mm) than in the slow one (58.2 +/- 5.4 mm), suggesting that the elongation of tendon structures at that time was significantly greater in the former than in the latter. Furthermore, at the initial stage of plantar flexion during the fast movement, the LF hardly changed with a rapid shortening of tendon structures at that time. The observed relation between MTC length and force showed that the behaviour of tendon structures contributed to 20.2 and 42.5% of the total amount of work completed during plantar flexion phase in the slow and fast movements, respectively. Thus, the present results suggest that tendon structures make the dynamics of MTC more efficient during stretch-shortening cycle exercises by changing their lengths.

Adult↗

PubMed2000

A case report of comorbid eating disorder and factitious disorder.

A review of the literature on comorbid eating disorder and factitious disorder reveals that they are very rare. In this report the authors present the case of a 26-year-old Japanese female, who, in the midst of treatment for eating disorder, was found to be fabricating her physical symptoms, by injecting unclean water into her intravenous bottle. As a result she was diagnosed with factitious disorder.

Adult↗

PubMed2000

Measurement of specific movement power application: evaluation of weight lifters.

A new dynamometer was developed for the measurement of specific movement power (SMP) exerted by mono- or multi-articular movements. To determine the reproducibility of SMP, two identical test protocols were carried out on separate days for six movement types on seven adult males. The movement types were arm pull (AP), leg rise (LR), knee extension (KE), elbow flexion (EF), hip extension (HE) and squat movement (SQ). Variations in peak power obtained in two tests ranged from 0.7% (AP) to 9.6% (SQ). Coefficients of the test-re-test correlation in peak power ranged from 0.805 (SQ) to 0.961 (AP) and standard errors ranged from 4 W (EF) to 14 W (SQ). SMP in upper extremities increased from 166 W (EF) to 307 W (AP) resulting from the increase in velocity. However, in the movements of lower extremities, SMP increased from 506 W (KE) to 1351 W (SQ) as a result of the increase in force. To evaluate the validity of the SMP, a pull movement in weightlifting was tested and related to the athletic performance on weightlifters. Positive linear correlation (r = 0.862, p<0.001) was observed between SMP and the total weight best records. It is concluded that this newly developed dynamometer has enough reproducibility and validity for evaluating the SMP, which is developed by various joint movement patterns related to the sport. The feasibility of applying this measuring protocol to the testing and training programmes for improving the daily living activities and athletic performances should now be assessed.

Adult↗

PubMed2000

Acute effect of alcohol on androgens in premenopausal women.

The aim of the present study was to investigate the effect of alcohol on androgen levels among premenopausal women. Eighty-seven women in the mid-cycle phase of the menstrual cycle, 47 of whom used oral contraceptives (OC+), were included in the study. The range for reported alcohol consumption was 0-4 drinks/day. The total testosterone levels were significantly higher after alcohol intake (0.5 g/kg) than after placebo at 45 min and 90 min from the start of drinking among both OC- and OC+ subjects. This effect was also seen in the free testosterone fraction. The effect on testosterone was more prominent among OC+ subjects. Androstenedione levels were significantly lowered and the testosterone:androstenedione ratio significantly elevated by alcohol among both OC- and OC+ subjects. No effect of alcohol on dehydroepiandrosterone or dihydrotestosterone levels was observed. A positive correlation was observed between the change in testosterone levels and the change in androstenedione levels during placebo conditions. The correlation was significantly reduced during alcohol conditions among OC+ subjects, indicating an increased androstenedione to testosterone conversion. No significant dose (0.34, 0.68 and 1.02 g/kg) or time (45, 90 and 150 min) effects on total testosterone were observed in a substudy involving 10 OC+ subjects. The present results suggest that the testosterone effect is related to the zero-order mechanism of ethanol oxidation. The observed testosterone and androstenedione effects are suggested to be the result of an increased androstenedione to testosterone conversion in the liver caused by the alcohol-mediated elevation in the [NADH]:[NAD(+)] ratio. The present findings may be relevant in the development of hyperandrogenism and loss of female sexual characteristics associated with heavy alcohol consumption.

Adult↗

PubMed2000

Effect of short-duration spaceflight on thigh and leg muscle volume.

PURPOSE: Human skeletal muscle probably atrophies as a result of spaceflight, but few studies have examined this issue. Thus, little is known about the influence of microgravity upon human skeletal muscle, nor is it possible to assess the validity of ground based models of spaceflight. This study tested the hypothesis that the magnitude of spaceflight induced muscle atrophy would be a function of flight duration and greater than that of bed rest. METHODS: Three astronauts flew 9, 15, and 16 d in space. Volume of the knee extensor (quadriceps femoris), knee flexor (hamstrings, sartorius, and gracilis), and plantar flexor (triceps surae) muscle groups was measured using magnetic resonance imaging before and after spaceflight and during recovery. The volume of each muscle group in each image was determined by multiplying cross-sectional area by slice thickness. These values were subsequently summed to calculate muscle volume. RESULTS: Volume changes in the knee extensor, knee flexor, and plantar flexor muscle groups ranged from -15.4 to -5.5, -14.1 to -5.6, and -8.8 to -15.9%, respectively. Muscle volume decreases normalized by flight duration ranged from 0.62 to 1.04% x d(-1). These relative changes appeared to be greater than those that we have reported previously for bed rest (Akima et al., J. Gravitat. Physiol. 4:15-22, 1997). CONCLUSIONS: These results suggest that atrophy as a result of at least 2 wk of spaceflight varied among individuals and muscle groups and that the degree of atrophy appeared to be greater than that induced by 20 d of bed rest.

Astronauts↗

PubMed2000

Effect of long-term atrial-demand ventricular pacing on cardiac sympathetic activity.

It has been shown that either dual-chamber or atrial pacing may be better than ventricular single-chamber pacing, but the long-term effect of dual-chamber pacing on cardiac sympathetic activity is unclear. The aim of this study was to assess the effect of long-term dual-chamber pacing on cardiac sympathetic activity, compared with atrial pacing and unpaced individuals. We studied 11 patients with dual-chamber pacemakers (Group D), nine with atrial single-chamber pacemakers (Group A) over the long term (mean 44 +/- 36 months) and 10 normal individuals without cardiac pacing. All underwent myocardial 123I-metaiodobenzylguanidine (MIBG) imaging to assess cardiac sympathetic activity. The heart-to-mediastinum (H/M) MIBG uptake ratio and the MIBG washout rate from the myocardium were calculated. Echocardiography was performed in all patients with cardiac pacing to assess left ventricular function. In Group D, the H/M ratio on delayed images was significantly lower than that of Group A (1.82 +/- 0.51 vs 2.56 +/- 0.50, P < 0.001) and normal individuals (2.65 +/- 0.35, P < 0.05). The myocardial MIBG washout rate of Group D was significantly higher than that of either Group A (52 +/- 13% vs 36 +/- 8%, P < 0.01) or normal individuals (31 +/- 7%, P < 0.05). Neither the H/M ratio nor MIBG washout rate differed significantly between patients in Group A and normal individuals. Furthermore, the echocardiographic parameters did not differ significantly between the two pacing groups. We conclude that long-term ventricular pacing, even in the presence of atrioventricular synchrony, accelerates cardiac sympathetic activity without deteriorating left ventricular function.

3-Iodobenzylguanidine↗

PubMed2000

In vivo estimation of contraction velocity of human vastus lateralis muscle during "isokinetic" action.

To determine the shortening velocities of fascicles of the vastus lateralis muscle (VL) during isokinetic knee extension, six male subjects were requested to extend the knee with maximal effort at angular velocities of 30 and 150 degrees /s. By using an ultrasonic apparatus, longitudinal images of the VL were produced every 30 ms during knee extension, and the fascicle length and angle of pennation were obtained from these images. The shortening fascicle length with extension of the knee (from 98 to 13 degrees of knee angle; full extension = 0 degrees ) was greater (43 mm) at 30 degrees /s than at 150 degrees /s (35 mm). Even when the angular velocity remained constant during the isokinetic range of motion, the fascicle velocity was found to change from 39 to 77 mm/s at 150 degrees /s and from 6 to 19 mm/s at 30 degrees /s. The force exerted by a fascicle changed with the length of the fascicle at changing angular velocities. The peak values of fascicle force and velocity were observed at approximately 90 mm of fascicle length. In conclusion, even if the angular velocity of knee extension is kept constant, the shortening velocity of a fascicle is dependent on the force applied to the muscle-tendon complex, and the phenomenon is considered to be caused mainly by the elongation of the elastic element (tendinous tissue).

Adult↗

PubMed2000

A new nasal acoustic reflection technique to estimate pharyngeal cross-sectional area during sleep.

The conventional acoustic reflection technique in which acoustic waves are launched through the mouth cannot be applied during sleep, nor can it be applied to the nasopharynx, which is the major site of occlusion in patients with obstructive sleep apnea syndrome. We propose a new technique of nasal acoustic reflection to measure pharyngeal cross-sectional areas including the nasopharynx. The acoustic waves are introduced simultaneously to both nostrils during spontaneous nasal breathing. A new algorithm takes into account the nasal septum with asymmetric nasal cavities on both sides and assumes prior knowledge of the cross-sectional area of the nasal cavities and the position of the nasal septum. This method was tested on an airway model with a septum and on healthy human subjects. The conventional technique gave inaccurate measurements for pharyngeal cross-sectional areas for an airway model with asymmetric branching, whereas the new technique measured them almost perfectly. The oro- and hypopharyngeal cross-sectional area measurements acquired by the new method were not different from those obtained by the conventional method in normal subjects. This new method can be used as a monitor of upper airway dimensions in nocturnal polysomnography.

Acoustics↗