Stochastic resonance in connectivity between both auditory areas obtained by auditory stimuli.

We examined coherence of auditory steady state responses (ASSRs) in magnetoencephalogram to an ongoing sinusoidal amplitude modulated tone presented to the subject's left ear while bursts of white noise of various intensities were presented to the right ear. The results showed a significant enhancement in the real part of coherence of ASSRs obtained from the right and left temporal regions by the presence of white noise of appropriate intensity. The observed stochastic resonance (SR) most likely occurred within the central nervous system, which is from lateral superior olive to medial geniculate body. Our finding may be quite important as mechanisms of SR in biological systems are mostly unknown.

Stochastic resonance in brain activity elicited by auditory stimuli.

We measured auditory steady state responses (ASSRs) in magnetoencephalogram to an ongoing sinusoidal amplitude modulated tone presented to the subject's left ear while bursts of white noise of various intensities were presented to the right ear. Because the power and coherence as functions of the noise to signal ratio differed considerably among subjects, we used their maximum values as test statistics for testing the group data. The results showed a significant enhancement in the phase coherence of ASSRs obtained over the right temporal regions by the presence of white noise of appropriate intensity. The observed stochastic resonance (SR) most likely occurred within the central nervous system. Our finding may be quite important as mechanisms of SR in biological systems are mostly unknown.

Leukaemic dissemination of Merkel cell carcinoma in a patient with systemic lupus erythematosus.

We describe an unusual bone-marrow metastasis of Merkel cell carcinoma (MCC) arising in the right cheek of a 73-year-old woman with systemic lupus erythematosus (SLE) and Sjögren's syndrome, who had been treated with oral prednisolone and methotrexate for 10 years. Seven months after wide local excision followed by local irradiation, the patient presented with thrombocytopaenia. Her bone marrow had been completely replaced by metastatic MCC cells, and metastatic cytokeratin 20-positive cells were also identified in the peripheral blood. To our knowledge, in the English literature, only six cases have been described previously of MCC bone-marrow involvement. Of these six cases, four were immunosuppressed, similar to our case. The high incidence of MCC in immunosuppressed patients such as those with SLE has been discussed previously. We consider that immunosuppression might be associated with bone-marrow metastasis, which is a rare form of MCC.

Stochastic resonance seen as increase in phase synchrony or power in auditory steady-state responses in MEG.

This report shows the first evidence that stochastic resonance can be triggered in the auditory steady state re-sponses (ASSRs) in MEG (magnetoencephalogram) which was indicated either by increased synchrony to the stimulus or by increase in power of ASSR when there was certain amount of noise in addition to the sinusoidal AM sound compared with the ASSR when there was no noise. To obtain the above conclusion, we applied statistical analysis to each subject's data rather than to the whole set of the data of all subjects because individual differences smoothed out the effect of noise addition when the data were averaged over all the subjects.

Tumour-like muscular sarcoidosis.

Sarcoidosis is a multisystem granulomatous disease of unknown aetiology with variable manifestations, which may affect virtually any organ. Muscular sarcoidosis is a rare entity, and among this group of muscular lesions, the tumour-like muscular sarcoidosis subtype is extremely rare. We report on two sarcoidosis cases that presented muscular sarcoid lesions with subcutaneous tumours.

Evidence from mucin core protein expression that some Paget's disease on areola can be of extramammary-like histogenesis and part of multisite disease.

Triple extramammary Paget's disease, which consists ordinarily of bilateral axillary and genital lesions, is uncommon. Triple extramammary Paget's disease involving other sites has never been reported, although solitary extramammary Paget's disease can occur at various sites around the body. Erythematous plaques on the areola, axilla and genitalia of a 91-year-old man were surgically removed under the clinical diagnosis of multiple extramammary Paget's disease. Histology revealed that all three lesions consisted of intraepidermal nests of Paget cells and other isolated Paget cells scattered in the epidermis. Although adnexal invasion was observed in the genital lesion, neither intraductal invasion nor underlying breast carcinoma was detected in the areolar lesion. Immunohistochemically, the Paget cells in all lesions expressed simple epithelial cytokeratins (CK8, 18 and 19), mucin (MUC)1 and MUC5AC, but neither CK20 nor MUC2. From the histological findings, the present case was interpreted as triple extramammary Paget's disease rather than synchronous mammary and extramammary Paget's disease. Furthermore, the mucin core protein expression pattern, which was identical to that observed in extramammary Paget's disease, supported the above interpretation.

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.

Magnetic phagosome motion in J774A.1 macrophages: influence of cytoskeletal drugs.

The role of the different cytoskeletal structures like microfilaments (MF), microtubuli (MT), and intermediate filaments (IF) in phagosome motion is unclear. These cytoskeletal units play an important role in macrophage function (migration, phagocytosis, phagosome transport). We investigated ferromagnetic phagosome motions by cell magnetometry. J774A.1 macrophages were incubated with 1.3-microm spherical magnetite particles for 24 h, after which more than 90% of the particles had been phagocytized. Phagosome motions can be caused either by the cell itself (relaxation) or by applying magnetic twisting forces, yielding cell stiffness and viscoelastic properties of the cytoskeleton. Apparent viscosity of the cytoplasm was non-Newtonian and showed a shear-rate-dependent power law behavior. Elastically stored energy does not force the magnetic phagosomes back to their initial orientation: 57% of the twisting shear was not recoverable. Cytoskeletal drugs, like Cytochalasin D (CyD, 2 - 4 microM), Colchicine (CoL, 10 microM), or Acrylamide (AcL, 40 mM) were added in order to disturb the different cytoskeletal structures. AcL disintegrates IF, but affected neither stochastic (relaxation) nor directed phagosome motions. CyD disrupts MF, resulting in a retarded stochastic phagosome motion (relative decay 0.53 +/- 0.01 after 5 min versus 0.34 +/- 0.01 in control), whereas phagosome twisting shows only a small response with a 9% increase of stiffness and a small reduction of recoverable strain. CoL depolymerizes the MT, inducing a moderately accelerated relaxation (relative decay 0.28 +/- 0.01 after 5 min) and a 10% increase of cell stiffness, where the pure viscous shear is increased and the viscoelastic recoil is inhibited by 40%. Combining the two drugs conserves both effects. After disintegrating either MF or MT, phagosome motion and cytoskeletal stiffness reflect the behavior of either MT or MF, respectively. The results verify that the dominant phagosome transport mechanism is MF-associated. MT depolymerization by CoL induces an activation of the F-actin synthesis, which may induce an accelerated relaxation and an increase of stiffness. Cell mechanical properties are not modulated by MF depolymerization, whereas MT depolymerization causes a loss of viscous resistance and a loss of cell elasticity. The mean energy for stochastic phagosome transport is 5*10(-18) Joules and corresponds to a force of 7 pN on a single 1.3-microm phagosome.

A viscoelastic model of phagosome motion within cells based on cytomagnetometric measurements.

Cytomagnetometry is a noninvasive method to investigate intracellular movements of organelles such as phagosomes by introducing magnetic particles into cells by phagocytosis, magnetizing them and measuring the field from the cells. To analyze the results of the cell-field measurement, we introduce a model for intracellular phagosome motion and investigate their behavior in terms of the cell field. The model includes an elastic body and two viscosity components which are ascribed to the filamentous structures surrounding the phagosomes. The magnetic relaxation phenomenon is assumed to derive from the rotationary Brownian motion as in our previous model. Although the model is simple, its behavior is not trivial because it contains a nonlinear term and the Brownian motion term. This model is the simplest one possible having a viscoelastic body and its behavior hence should be investigated thoroughly.

Force generation capacity of knee extensor muscles in speed skaters.

The force generation capacities during a single as well as repetitive maximal knee extensions were investigated in speed skaters in relation to the cross-sectional area (CSA) of quadriceps femoris muscles. The subjects were 15 male and 12 female speed skaters, and an age-matched untrained group (20 men and 21 women). An isokinetic dynamometer was used to determine force output at three constant velocities of 1.05, 3.14 and 5.24 rad.s-1 and to perform 50 repetitive maximal contractions at 3.14 rad.s-1. The CSA was measured by using a B-mode ultrasound technique at the midpoint of the thigh length. The isokinetic force produced at each test velocity was significantly correlated to CSA in all the subjects (r = 0.867-0.920, P < 0.05). There was no significant difference in force (F) per unit CSA (F.CSA-1) at the three test velocities between the speed skaters and untrained subjects within the same sex. In both the speed skaters and untrained subjects, the women showed significantly lower F.CSA-1 at 3.14 and 5.24 rad.s-1 than the men. The means of force output (F) of every five consecutive and all trials during the repetitive maximal bout were significantly correlated to CSA in all the subjects (r = 0.889-0.934, P < 0.05). Compared to the untrained subjects, the speed skaters showed significantly higher F for every five consecutive contractions even when calculated per unit of CSA (F.CSA-1), and had lower percentage of decline of F during a trial span between the 6th-10th and 41st-45th trials. For the untrained subjects, F.CSA-1 for every five consecutive contractions was significantly lower in the women than in the men. For the speed skaters, the men showed significantly higher F.CSA-1 than the women during a trial span from the 1st-5th trial to the 31st-35th trial, although there was no significant sex difference in the ratio on and after the 36th-40th trial. From these results, it is concluded that the speed skaters show a higher muscle performance in a repetitive maximal contraction task rather than in a single contraction compared to the untrained subjects. In addition, judging from the results for the speed skaters, the women might be less trainable than the men in the F.CSA-1 during a single contraction at a fast velocity as well as repetitive maximal contractions.

Muscle metabolism during exercise using phosphorus-31 nuclear magnetic resonance spectroscopy in adolescents.

Very little has been reported on muscle energetics during exercise in adolescents. This is attributable to the difficulty of subjecting children to muscle biopsy. The purpose of this study was to investigate the characteristics of muscle metabolism during exercise in vivo in adolescents by comparing firstly, with adults and secondly, the differences resulting from physical activity using phosphorus-31 nuclear magnetic resonance (31P NMR) spectroscopy. The subjects were boys aged 12 to 15 years, comprising 21 trained boys and 23 control boys, and 6 adults controls. The ratio of phosphocreatine (PCr):(PCr + P(i)), where P(i) is inorganic phosphate intracellular pH at exhaustion and the time constant of PCr during recovery were measured in all the subjects using 31P NMR. Both groups of children showed higher values of PCr:(PCr + P(i)) and intracellular pH at exhaustion than did the adult control group (P < 0.01 or P < 0.05). However, no significant differences were found between the trained boys and the control boys with respect to PCr:(PCr + P(i)) and intracellular pH at exhaustion. On the other hand, we found the same values for PCr time constant in all groups. This result suggested no differences of the muscle oxidative capacity between children and adults. We concluded that the adolescents, aged 12 to 15 years in both the trained and control groups, had less glycolytic ability during exercise than the adults.

A model of phagosome motion within cells based on cytomagnetometric measurements.

Cytomagnetometry is the study of the intracellular movement and rheological properties of living cells by magnetic measurement. This paper summarizes the mathematics involved in the measurement and proposes a new model of phagosome motion in which a motor protein such as myosin and a protein filament such as microfilament play the role of the actomyosin system in the muscle. The rotational random walk is assumed to result from interactions of these proteins. The model makes predictions about the results of the experiments employing magnetic particles introduced into the cells by phagocytosis. The predictions are qualitatively consistent with the results of recent preliminary experiments.

Use of ferrimagnetic particles as a probe for phagocytic activities and intracellular movements of microstructures of pulmonary macrophages.

Magnetic particles such as Ni and gamma-Fe2O3 were used for estimating the phagocytic rate of hamster pulmonary macrophages in vivo and investigating various aspects of intracellular movement of organelles and filamentous structures. This technique, though in its premature stage, implies quite a large area of applications from cellular physiology to environmental sciences. This paper briefly reviews our work done in this field to date.

The effect of sports training on the age-related changes of body composition and isokinetic peak torque in knee extensors of junior speed skaters.

To elucidate the effect of sports training on age-related changes of body composition and isokinetic peak torque (IPT) in knee extensors, junior speed skaters were tested in comparison with relatively sedentary age-matched controls. Subjects consisted of 132 male and 71 female junior speed skaters (SSs; aged 10-18 years). Two-hundred and thirty-six males and 265 females between the ages of 10 to 18 in the same geographic area were also tested as controls (Cs). Lean Body Mass (LBM) and relative body fat (%) were estimated from skinfolds, using the equations for preadolescent boys and girls. An isokinetic dynamometer (Cybex II) was used to measure IPT (Nm) produced at angular velocities corresponding to 0, 30, 180, 300 deg.sec-1 during maximal knee extensions. SSs were heavier in body weight and LBM from age 13 for males and from age 16 for females than the Cs, and there were significant differences in LBM between SSs and Cs after age 16 regardless of sex. The female Cs showed a gradual increase in relative body fat (%) after age 14, however, such a trend was absent in female SSs. IPT increased in any angular velocity with age from 10-18 years in the male Cs, and from 10-15 years in the female Cs. On the other hand, male SSs tended to be stronger after age 13 and female SSs stronger after age 16. Significant differences between the two groups were obtained only at lower angular velocities from 16 years of age in both sexes.(ABSTRACT TRUNCATED AT 250 WORDS)

Estimation of the energy of cytoplasmic movements by magnetometry: effects of temperature and intracellular concentration of ATP.

Ferrimagnetic particles (gamma-Fe2O3) were spontaneously phagocytized by pulmonary macrophages obtained from the lungs of hamsters. By the magnetometric method proposed earlier, changes in the energy of the movements of the intracellular structures and also that of the apparent viscosity of the cytoplasm were estimated. The changes were created by lowering the incubation temperature or by decreasing the intracellular concentration of ATP. While the low temperature decreased the energy and increased the apparent viscosity, the low concentration of ATP decreased the energy but had little effects on the apparent viscosity. Estimation of the these parameters was based on the model previously proposed.

Magnetometric estimation of organelle motion in hamster lung macrophages in vitro: the effects of temperature.

Pulmonary macrophages, containing ingested ferrimagnetic particles, were studied in vitro. Magnetic particles (Fe3O4) suspended in saline were repeatedly instilled intratracheally into the lungs of Syrian golden hamsters. Later the animals were sacrificed and pulmonary macrophages were harvested by repeated lung lavage. After monolayer cultures were established, the particles previously phagocytized by the macrophages were magnetized and aligned by applying an external field. After the external field was removed, the particles produced a remanent magnetic field which gradually decreased due to random misalignment of the particles (relaxation). When relaxation was measured at various incubation temperatures, we found that relaxation slowed as the temperature decreased; we believe that this reflects decreased organelle motion. These results provide direct evidence that relaxation measured previously in intact animals is related to intracellular movements. Magnetometry can be used to quantitate the motion of cell organelles and thus the influence of altered cytoplasmic rheology and cytoskeletal activity.

Aerobic threshold, anaerobic threshold, and maximal oxygen uptake of Japanese speed-skaters.

The purpose of this study was to investigate the physiologic and metabolic parameters of speed-skaters with different training regimes and performance level and examine some physiologic prerequisites for speed-skating. The subjects were 25 male speed-skaters including members of the 1984 Japanese National Speed Skating Team whose ages ranged from 19 to 25 years. Aerobic threshold (AerT), anaerobic threshold (AnT), and VO2max were determined during a progressive bicycle ergometer exercise. The power was increased by 12.25 W every 3 min to exhaustion. AerT was determined using gas exchange variables; nonlinear increase in VE and VCO2, and peak VO2.VE-1. AnT was estimated from breakaway VE and the onset of decrease in FECO2.VO2max was measured during another incremental exercise on a bicycle ergometer. Mean AerT, AnT, and VO2max for skaters (n = 25) were 2.47 +/- 0.36.min-1 (61.1 +/- 7.2 %VO2max), 2.93 +/- 0.33.min-1 (73.4 +/- 5.9 %VO2max), and 4.06 +/- 0.42.min-1, respectively. All-arounders had higher AerT values but the same VO2max as sprinters. AnT of all-arounders was significantly higher than those of sprinters. A significant difference between the top ten elite skaters and the other skaters (n = 15) was found only in VO2max expressed as l.min-1. However, no significant correlation was noted between measured physiologic variables (AerT, AnT, and VO2max) and performances expressed as mean velocities at various events.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomagnetism in Japan.

The study of biomagnetic fields originating in a biological body is called biomagnetism. Among various fields of biomagnetism, this paper reviews the research and clinical works in magnetocardiogram, neuromagnetism, magneto-oculogram, magnetopneumogram and magnetic measurement for cell motility carried out in Japan.