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In this paper, we designed an artificial blood-circulation system and an original medical device for the improvement of blood flow. First, we prepared an electromagnetic flowmeter and an adaptable coil conformed to the imitative system. The sinusoidal and rectangular signals emitted were sampled with a differential amplifier. Under a constant liquid-flow rate of 7.5 L/min at the alternating electromagnetic field strength of 20 mT, we were able to obtain an induced electromotive force of approximately 2.8 mV. In addition, we investigated the potential of some frequency-changing items to act as a new life-support device for clinical applications. By modifying a commercial magnetic field machine, we designed a prototype equipped with frequency switching of 50 and 0.5 Hz to trial a cure for poor lower limb intravenous flow, lower limb edema, and venous thrombus formation. These systems may provide new knowledge about a mechanism of blood massotherapy by electromagnetic stimulations in the developments of alternating magnetic field machines.

Objectives: We performed a cytotoxicity study by cell magnetometry, measured lactate dehydrogenase (LDH) activity by enzyme assay, detected DNA ladder formation, and performed morphological examination by electron microscopy in order to evaluate the safety of high temperature wool (HT wool), an asbestos substitute, using long and short chrysotile fibers (CF) as positive controls and phosphate buffered saline (PBS) as a negative control. Methods: Alveolar macrophages were isolated from male Fisher rats. Following the addition of iron oxide particles (Fe3O4) to macrophages, HT wool, long or short CF was added. Then, the remanence strength was measured for 20 min after magnetization by an external field. Percent LDH release was calculated after determining LDH activity. DNA was detected using an apoptosis detection kit. Morphological observation was performed by taking electron micrographs of macrophages in the groups treated with HT wool and long- and short-CF. Results: Rapid relaxation, an indicator of decay of cytotoxicity, was observed by cell magnetometry immediately after magnetization was ended in the groups treated with HT wool and PBS, showing that HT wool causes no harmful effect on the cytoskeleton. The CF-treated groups had higher LDH activity than the PBS- and HT wool-treated groups. No fragmentation of DNA was observed in any group. In morphological observation, cytotoxicity in macrophages was lower in the HT wool-treated groups than in the CF-treated groups. Conclusions: The results suggest that HT wool has no cytotoxicity, as evaluated by cell magnetometry, enzyme assay, DNA ladder detection and morphological examination.

This study was carried out to assess the cytotoxicity of three kinds of refractory fibers (RFs), RF1, RF2, and RF3, by cell magnetometry, lactate dehydrogenase (LDH) assay and morphological observation by scanning electron microscopy, using a mouse-derived cultured cell line, RAW264.7. As an indicator for cell magnetometry, Fe(3)O(4) was added to RAW264.7 cells. RF1, RF2 and RF3 were each added to an aliquot of this solution to make final concentrations of 250, 500 and 1,000 µg/ml in the experimental group. Phosphate buffered solution was added to make the control solution (n = 6). After culturing for 48 hr, the solution was magnetized from outside using a cell magnetometric apparatus, and the remnant magnetic field was measured for 20 min postmagnetization. In cell magnetometry, a significant delay of relaxation compared to that of the control was observed. In the LDH assay, LDH release into the culture medium was observed by addition of RFs. Furthermore, a quantity-dependent relationship was found between the quantity of RF added and the cytotoxicity in cell magnetometry and LDH assay. Morphological examination revealed incomplete phagocytosis of fibers and a decrease of microvilli in the experimental groups. These results suggest that RFs are cytotoxic to RAW264.7 cells, showing concentration-dependent cytotoxicity, and have a possible risk of cytotoxicity similar to that of asbestos. Further studies by pulmonary magnetometry are necessary to assess the hazardousness of RFs.

The cytotoxicity of rock wool (RW), an asbestos substitute, was evaluated by cell magnetometry. Alveolar macrophages were isolated from male Fisher rats. Following addition of triiron tetraoxide (Fe 3 O 4 ) to macrophages, RW was added. Then, the remnant magnetic field strength was measured for 20 min after magnetization by an external field. Relaxation, an indicator of decay of cytotoxicity, was observed by cell magnetometry immediately postmagnetization in the group to which RW was added. In general, materials phagocytosed by macrophages are ingested into phagosomes and digested while migrating. This migration of phagosomes occurs by polymerization and depolymerization of the cytoskeleton. As a result of evaluation, relaxation was not delayed by addition of RW, since RW caused no effect on the cytoskeleton. It was suggested that RW has no cytotoxicity as evaluated by cell magnetometry.

To synthesize artificial bones, the collagen orientation is one of the key issues. It is reported that high magnetic field could be generated by superconducting magnets, are effective in controlling collagen orientation. In this paper, magnetic circuit using permanent magnets for collagen orientation is studied. As the results, a compact magnetic circuit with magnetic field strength around 3 T has been developed. By using the magnetic circuit, collagen was highly oriented, and orientation order was 0.9. Mouse osteoblast cells were seeded on the orientated collagen solution and cultured. The collagen-gel shrinkages by cells were observed. The shrinkage rates of oriented collagen are higher than that of not oriented one. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

In this study, highly oriented collagen structures were successfully synthesized using a conventional superconducting magnet with magnetic field intensities of 2.5 to 8 T. The relationship between the orientation order parameters f 2D of osteoblasts cells (that is, the orientation of collagens) and the magnetic field intensity was mainly investigated. As a result, it was clarified that collagens highly oriented perpendicular to the magnetic field direction were obtained by exposure to a magnetic field intensity of 3.0 T.

In the biomagnetic measurement, the biomagnetic signal is extremely weak compared with environmental magnetic noise. Therefore, it is important to reduce the noise component. There are many noise-reduction studies for MEG using Independent Component Analysis (ICA). The ICA method is expectable to extract and remove noise components from the brain magnetic field measurement data. However, in these researches, each obtained independent components are artificially distinguished to the noise and the signal. We propose a method of distinguishing to the noise and the signal automatically by using the signal subspace method for vector brain magnetic field. By applying this method to a phantom data and Auditory Evoked Field data, it is shown improvement of the signal to noise ratio and estimated accuracy.

Rock wool (RW), a type of man-made mineral fiber (MMMF), is a building material used as an asbestos substitute for heat insulation, fire resistance, and reinforcement. RW is included in group 3 of the IARC classification. In the present study, the cytotoxicity of RW was investigated by cell magnetometry, enzyme assay, DNA ladder detection, and electron microscopic morphological evaluation in comparison with chrysotile fibers (CF). Specimens were prepared by 18-h incubation of Fischer rat alveolar macrophages in the presence of RW fibers as the study material, CF as positive control, and phosphate-buffered saline (PBS) as negative control, together with a relaxation indicator, Fe3O4, except for morphological evaluation, followed by additional procedures of external magnetization and subsequent 20-min remanent magnetic field measurement for magnetometric evaluation, and macrophage DNA extraction for evaluating possible apoptosis by DNA ladder detection. In magnetometry, relaxation, a marker of cytotoxicity, was rapid in both the RW- and PBS-treated groups, while it was delayed in both the long and short CF-treated groups. Differences in percent lactate dehydrogenase (LDH) release between the RW-treated group and PBS-treated group were not significant, but those between the RW-treated group and short CF-treated group were statistically significant. A DNA ladder was not detected in any of the study groups. Electron micrographs showed that RW did not cause any change, but CF caused changes in macrophages. Thus, magnetometric measurements suggested no cytotoxicity of RW. We plan, in the future, to evaluate the safety of RW by magnetometric measurement and morphological observation of the lungs in in vivo inhalation experiments.

Alveolar macrophages are thought to play a major role in the pathophysiology of lung diseases caused by exposure to various kinds of pathogens and particles. In the present study, the cytotoxic effect of potassium octatitanate whisker(PT) on macrophages was evaluated by means of magnetometry, lactate dehydrogenase (LDH) release measurement, apoptosis measurement and morphological observations. Alveolar macrophages obtained from Fischer rats (F344/N Slc) by bronchoalveolar lavage were incubated in vitro for 18 h with Fe3O4 as a magnetometric indicator, and PTs as test materials. In the control group and the group exposed to 10 μg/ml of PT, rapid attenuation of the remanent magnetic field (RMF), so called “relaxation, ” was observed immediately after cessation of the external magnetic field. In comparison, a delay of relaxation was observed in alveolar macrophages exposed to 20 and 40 μg/ml of PT. The decay constants, which are calculated from decreasing RMF for the first 2 min, in the groups exposed to 20 and 40 μg/ml of PT had significantly lower values than the control. LDH release induced by exposure to 20 and 40 μg/ml of PT increased significantly in a concentration dependent manner in PT-exposed macrophages, whereas only negligible LDH release was observed in control groups. The level of PT affecting alveolar macrophages was at the same concentration, and in a dose-dependent manner among relaxation, decay constant and LDH measurement. A DNA ladder detection method and morphological observations detected no apoptosis in PT-exposed macrophages. Electron microscopic examination revealed vacuolar changes and cell membrane damage in PT-exposed macrophages, but no significant changes in control macrophages. The results of magnetometry, LDH release, apoptosis measurement and electron microscopic observations suggest concentration dependent cytotoxicity caused by exposure of alveolar macrophages to PT.

The present study was conducted to clarify the toxicity of Indium arsenide (InAs) particles to alveolar macrophages of hamsters by cytomagnetometry, enzyme release assays and morphological examinations. One million alveolar macrophages obtained from hamsters were exposed to 60 microg of ferrosoferric oxide and 2, 4, 10 and 20 microg of InAs particles. Relaxation, which is the rapid decline of strength of the remanent magnetic fields radiating from the alveolar macrophages, was insignificantly delayed and decay constants were not changed due to exposure to such doses of InAs. Because the relaxation is thought to be associated with the cytoskeleton, the exposure to InAs may not have impaired their motor function. An LDH release assay and morphological findings indicate slight damage to macrophages. DNA electrophoresis and the TUNEL method revealed neither necrotic changes nor apoptotic changes. Thus, InAs particles at such doses hardly cause cytostructural changes and cell death.

Alveolar macrophages are considered to play a major role in the pathophysiology of lung diseases caused by exposure to various kinds of pathogens and particles. In this study, the cytotoxic effect of different shapes of titanium dioxide (TiO(2)) was evaluated on macrophages using a unique magnetometry method and was compared with conventional methods of lactate dehydrogenase (LDH) release, apoptosis measurement, and morphological observations. Alveolar macrophages obtained from Fischer rats (F344) by bronchoalveolar lavage were incubated in vitro for 18 h with Fe(3)O(4) as a magnetometric indicator and fibrous and particulate forms of TiO(2) as test materials. In the control and particulate exposed group, rapid attenuation of the residual magnetic field, so-called "relaxation," was observed immediately after cessation of the external magnetic field. In comparison, a delay of relaxation was observed in alveolar macrophages exposed to fibrous TiO(2). LDH released into serum-free medium induced by exposure to TiO(2) increased significantly in a concentration-dependent manner in macrophages exposed to fibrous TiO(2), while negligible LDH release was observed in macrophages exposed to particulate TiO(2). The DNA ladder detection method and morphological examination detected no apoptosis in macrophages exposed to 60 micro g/ml of fibrous or particulate TiO(2). Electron microscopic examination revealed vacuolar changes and cell surface damage in macrophages exposed to fibrous TiO(2), but no significant changes in macrophages exposed to particulate TiO(2). The results of magnetometry, LDH release, and electron microscopy suggest that cytotoxicity of TiO(2) depends on the shape of the material.

Gallium arsenide (GaAs) causes various toxic effects in animals, including pulmonary diseases. Although their toxicity is not completely investigated, GaAs is used in workplaces in various semiconductor products. The present report was designed to clarify the toxicity of GaAs suspension and arsenic chloride (AsCl 3 ) solution as additives to the alveolar macrophages in hamsters using magnetometry, enzyme release assays and morphological examinations. Alveolar macrophages obtained from hamsters by tracheobronchial lavage and adhered to disks in the bottom of wells were exposed to ferrosoferric oxide and additives. Ferrosoferric oxide particles were magnetized externally and the remanent magnetic field was measured. Relaxation, a fast decline of remanent magnetic fields radiated from alveolar macrophages, was delayed and decay constants decreased dose-dependently due to exposure to GaAs suspensions. Relaxation was much delayed and decay constants decreased considerably due to exposure to AsCl 3 solutions. Because the relaxation is thought to be associated with the cytoskeleton, exposure to GaAs impairs their motor function. Enzyme release assay and morphological findings indicated damage to macrophages. Thus the cytotoxicity caused cytostructural changes and cell death. According to DNA electrophoresis and TUNEL methods, necrotic changes occur more frequently than apoptotic changes. In conclusion, exposure to GaAs suspension and AsCl 3 solution induced cytotoxicity of alveolar macrophages.

To find out which brain regions are responsible for the mental construction and recognition of a kanji character initiated by visually presented kanji radicals, rather than by information retained in the memory, a left hen radical and the corresponding right tsukuri radical were simultaneously presented randomly to either the left or right visual field of seven subjects. Thirty left hen radicals and the corresponding right tsukuri radicals were prepared as stimuli; this combination formed over 500 real or pseudo kanji characters. Instead of their usual left and right positions, the left hen radical was always presented above the right tsukuri radical. As quickly and correctly as possible, the subjects released a key when two kanji radicals constituted a single real kanji character and released another key otherwise. We recorded neuromagnetic responses as well as accuracy and reaction time. Left visual field superiority was observed as regards accuracy. This is in good agreement with previous neuropsychological results. Equivalent current dipoles were localized mainly in the left and/or right occipitotemporal regions (ventral visual pathways), the bilateral occipitoparietal regions (dorsal visual pathways) including the supramarginal region, and the areas surrounding the left superior temporal cortex. We suggest that these regions are related to reading and the mental construction of a kanji character from its radicals.

We have developed a whole-head magneto-encephalogram system having 65 detection sites for detecting vector components of the magnetic field of the brain. Each site contains three first-order gradiometers, and the three detection coils of the gradiometers are perpendicular to each other. This configuration enables the radial and tangential components at each measuring site to be calculated. The helmet shaped dewar is held on a stand fixed to the floor inside the MSR (magnetically shielded room), and the tilt angle of the dewar is adjusted to fit the head. A square-double washer DC-SQUID having a large transfer function d V /d Φ (of the order of mV/ Φ 0) is used in the gradiometer. The large d V /d Φ enables the low-noise SQUID to be coupled directly to the pre-amplifier without additional positive feedback (APF). The typical noise of the system in the MSR is less than 10 fT/√Hz. Linearized output from the flux locked loop circuit is fed into the amplifier-filter unit, and digitized by an A/D converter. The brain function data from 195 channels are stored and analyzed by the workstation.

The paper presents a morphological study of real-time magnetocardiograms (MCGs) of a normal subject. The MCGs were measured by using a 3-D second-order gradiometer connected to three rf-SQUIDs in a prefabricated magnetically shielded room. The base line of the detecting coil for Bz is 2.8 cm and that of the coil for Bx and By is 1.4 cm. The magnetic field components perpendicular to the chest (Bz component) and tangential to the chest (Bx, By components) were studied. From isofleld contour maps and arrow maps of the QRS wave of the MCG, when multiple sources exist simultaneously, we can infer the locations and positions of different sources by combining the Bz component with the Bx and By components. The analyzed results showed that a method using of a 3-D second-order gradiometer that we developed is useful for discriminating the directions and locations of multiple sources.

Auditory evoked cortical responses, electric N1 and magnetic N1m, increase when the interstimulus interval (ISI) increases. We assumed that the response to a tone is mainly affected by the immediately preceding ISI, by the immediately preceding pause between stimuli (PBS) and by the previous stimulus duration (PSD). These 3 values are connected by the following expression: ISI = PBS + PSD. We examined the dependence of the auditory evoked brain magnetic responses on the ISI with the constant PSD (conventional paradigm), on the PBS with the constant ISI, and on the ISI with the constant PBS. Peak latencies and peak amplitudes of the 3 components, P1m, N1m and P2m, are recorded in one block using all possible combinations of 5 PSDs (0.05, 0.5, 1.0, 1.5 and 2.0 s) and 5 ISIs (0.5, 1.0, 1.5, 2.0 and 2.5 s). Peak latencies of these 3 components do not show any significant dependence either on the PBS or on the ISI. Neither the PBS nor the ISI brings a statistically significant effect on the P1m peak amplitude. On the other hand, the N1m peak amplitude increases as either the PBS (constant ISI) or the ISI (constant PSD) increases. The regression coefficient to the PBS is more than a double of that to the ISI. Moreover, the ISI does not show any significant effect on the N1m peak amplitude when the PBS is constant. This stronger PBS effect means that the N1m peak amplitude dependence on the ISI, which has been reported in several papers using the constant PSDs, includes more dependence on the PBS. The P2m peak amplitude shows the same tendency as the N1m because of the strong correlation in peak amplitude between them.

Now, we have relied upon X-rays for the diagnosis of such diposits, even though minute particles lodged in the lungs for long periods are almost impossible to detect with X-rays. Thus illnesses are not detected until the condition worsens and produces changes in the structure of the lungs. When such condition become detectable with X-rays, it is already too late to transfer the patient within the company:after the particulates have been deposited in the lungs, there is a tendency for the illness to progress. In any case, then, it's essential that we know the quantity of particles in the lungs before illness occurs. It is the method of the lung's magnetic figure that measure the total quantity and distribution of materials accumulated in the lungs by using the magnetic characteristic of particles. This method adds a magnetic field of strong direct current from the outside to particles are accumulated in the lungs. it magnetizes the particles and after taking out the outside magnetic field, these particles occur a slight magnetic field outside as a remaining magnetism. It's possible to get the quantity and distribution of particles are accumulated in the lungs by measuring this magnetic field on the surface of the body.

Intratracheal instillation of a GaAs suspension has been histopathologically shown to induce a diffuse pulmonary response. In the present study, magnetometry was used to evaluate the effects of intratracheally instilled GaAs and Ga2O3 on the behavior of externally magnetized iron oxide (Fe3O4) particles instilled in rabbit lung. Magnetometric evaluation of the effects of GaAs in rabbits dosed with 30 mg or 300 mg per animal showed a significantly decreased relaxation of iron oxide particles at 1, 3, 7, 14, 21 and 28 days following instillation compared with the controls. On the other hand, in the rabbits exposed to Ga2O3, significantly reduced decay constants were observed only on the first and third days following instillation. Relaxation indicates a rapid decrease of remanent magnetic field following magnetization of the lungs due to random rotation of phagocytosed iron oxide particles in macrophages. Clearance of the iron oxide particles was measured by serial determinations of the remanent magnetic field at the end of magnetization estimated from relaxation curves. Clearance was significantly impaired at 14, 21 and 28 days after instillation in rabbits exposed to both doses of GaAs. Slightly delayed clearance was also observed in rabbits exposed to Ga2O3. Histological examination of lungs instilled with GaAs indicated active phagocytosis of GaAs and iron oxide particles by pulmonary macrophages, as well as pneumonocytes hyperplasia with marked thickening of the alveolar walls. Minimal histological changes with retention of iron oxide particles were found in the lungs exposed to Ga2O3.

This paper describes the design and development of a hexagonal prefabricated magnetically shielded room (PMSR) for highly sensitive measurements of neuromagnetic fields such as magnetoencephalography (MEG), using SQUIDs with first-order and/or second-order gradiometers. This PMSR consists of prefabricated plywood panels 1.2 m wide × 2.4 m high × 24 mm thick, and covers a floor area of about 9 m2. These panels are sandwiched between two layers of high-m metal sheets 1 mm thick. The shielding factor at the center of the PMSR against external magnetic fields is 20 to 40 dB at frequencies from dc to 120 Hz. Magnetic noise inside the PMSR measured by a second-order gradiometer was less than several hundred fT at frequencies above 0.5 Hz, except for 50 Hz. For this measurement, the second-order gradiometer was able to eliminate the common-mode magnetic noise near 20 Hz produced by vibrations in the PMSR and observed on a magnetometer. These results are discussed, making comparisons with calculations.

This article describes the present status of research on biomagnetism, an interdisciplinary field of research involving biology, engineering, medicine, physics, psychology and other areas. Biomagnetic fields are caused either by electric currents in conducting body tissues such as the heart, the brain and muscles, or by magnetized material in lung contamination. These magnetic fields, although measurable, are so extremely weak that a superconducting quantum interference device (SQUID) magnetometer with ultra-high sensitivity is needed to detect magnetic flux generated outside the human body. This paper mainly focuses on the remarkable progress of research on biomagnetism involving magnetoencephalograms (MEGs) and magnetocardiograms (MCGs), and on the introduction of SQUID systems for measurement of biomagnetic fields.

There have been virtually no reports on the origin of environmental magnetic fields which act as noise sources in biomagnetic measurements, despite its importance to the design of magnetic shielded rooms and to the quality of signals obtained in biomagnetics experiments. In this paper, the measured variation of environmental magnetic fields at three locations-- Tokyo Denki University, Hokkaido University, and the Research Laboratory of Takenaka Corp.--is described, and the origin of magnetic field noise is discussed with reference to magnetic fields generated by electric trains. Near railways, large variations in magnetic field are observed due to imbalance between the feeder line and return rail line. Simulations confirmed that trains are especially prone to generate fields in the X-axis direction (perpendicular to the direction of train travel).

Magnetocardiogram (MCG) measurement using high-Tc SQUID magnetometer is receiving attention as a diagnostic technique because the instrument is easy to operate and the liquid nitrogen coolant is lower cost compared with the liquid helium used in conventional SQUID magnetometers. We measured of the linear current and MCG of the subjects with healthy and unhealthy hearts using a 16-channel high-Tc SQUID in a prefabricated magnetically shielded room. The spatial filter method (SFM) is used to reduce the errors in the measurement and analyzes of the signal source. The results of the simulation and actual measurement of the subjects with healthy and unhealthy hearts show that the method is useful for the estimation of the signal source.

The toxic effects of man-made mineral fibers (MMMFs) have been evaluated by cell magnetometry using alveolar macrophages (AMs). Recently, on the other hand, the murine macrophage cell line, RAW 264.7, became available and has been used as an in vitro model of AMs. The objective of this study was to determine whether or not cell magnetometry using RAW 264.7 cells can be used to evaluate the toxic effects of MMMFs. RAW 264.7 cells were exposed to one of the MMMFs, potassium octatitanate (PT) or silicon carbide whisker (SiC) at 0, 20, 40 and 60 microg/ml, or chrysotile as a positive control at 0, 15, 20 and 25 microg/ml. The toxic effects of fibers were evaluated by cell magnetometry and LDH assay. For this comparison, AMs were also exposed to chrysotile fibers (CF). In the RAW 264.7 cells exposed to PT 20, 40, 60 or SiC 20, 40, 60, CF 15, 20 and 25 microg/ml, significant delayed relaxation were observed compared with the respective control. In the LDH assay, significant increases in LDH in the supernatant of the cells exposed to PT 20, 40, 60, SiC 20, 40, 60 and CF 15, 20, 25 microg/ml were observed. In AMs exposed to CF 20, 25 microg/ml significant delayed relaxation and significant increases in LDH compared with the control were observed. The levels of MMMFs that induced significant differences were similar for cell magnetometry and LDH. The levels of CF that induced significant differences in cell magnetometry and LDH were identical for RAW 264.7 cells and AMs. Our results suggest that cell magnetometry using RAW 264.7 cells is adequate to evaluate the cytotoxicity of exposure to MMMFs.

In this study, a simple magnetic circuit for the collagen orientation using permanent magnets was developed.

A dynamical associative network is constructed with chaotic neuron models interconnected through an auto-correlation synaptic matrix. Dynamics of the network with external inputs are analysed by output pattern sequences, the largest Lyapunov exponent and response characteristic to perturbations.

The toxicity of microglass fibers (MG), one of the man-made mineral fibers, has not been sufficiently evaluated. The aim of the current study was to evaluate the cytotoxicity of MGin vitro.Alveolar macrophages were obtained from the bronchoalveolar lavage of male F344/N rats. The macrophages were exposed to MG at concentrations of 0, 40, 80, 160 and 320 μg/ml. The effects of MG on the macrophages were examined by cell magnetometry, LDH assay and morphological observation.In the cell magnetometry experiment, a significant delay of relaxation (the reduction of remanent magnetic field strength) was observed in the cells treated with 160 and 320 μg/ml of MG in a dose-dependent manner. A significant increase in LDH release was also observed in the cells with 160 and 320 μg/ml in a dose-dependent manner. Changes in the cytoskeleton were observed after exposure to MG by immunofluorescent microscopy using an α-tubulin antibody.The cytotoxicity of MG on alveolar macrophages was demonstrated with cell magnetometry. The mechanism of the toxic effects of MG was related to cytoskeleton damage.

Linguistic experience alters an individual's perception of speech. We here provide evidence of the effects of language experience at the neural level from two magnetoencephalography (MEG) studies that compare adult American and Japanese listeners' phonetic processing. The experimental stimuli were American English /ra/ and /la/ syllables, phonemic in English but not in Japanese. In Experiment 1, the control stimuli were /ba/ and /wa/ syllables, phonemic in both languages; in Experiment 2, they were non-speech replicas of /ra/ and /la/. The behavioral and neuromagnetic results showed that Japanese listeners were less sensitive to the phonemic /r-l/ difference than American listeners. Furthermore, processing non-native speech sounds recruited significantly greater brain resources in both hemispheres and required a significantly longer period of brain activation in two regions, the superior temporal area and the inferior parietal area. The control stimuli showed no significant differences except that the duration effect in the superior temporal cortex also applied to the non-speech replicas. We argue that early exposure to a particular language produces a "neural commitment" to the acoustic properties of that language and that this neural commitment interferes with foreign language processing, making it less efficient.

The authors introduce chaos into simple mathematical neuron models which are deterministic rather than probabilistic. The authors apply chaotic dynamics to artificial neural networks, using a chaotic neuron model based on electrophysiological experiments with squid giant axons and on numerical experiments with the Hodgkin-Huxley equations. First, the authors explain the chaotic neuron model and its dynamics. The authors also demonstrate spatio-temporal pattern dynamics of chaotic neural networks with nearest-neighbor couplings. It is shown that the chaotic neural networks with nearest-neighbor couplings have abundant spatio-temporal dynamics with a possible applicability to dynamical spatio-temporal memory. >

Photocopier toner has been implicated in the etiology of some pulmonary diseases. We examined here the in vitro toxicity of toner particles to alveolar macrophages. Cell magnetometry revealed that relaxation was not delayed in macrophages exposed to toner, which represents a rapid decrease in the remaining magnetism emitted by phagocytosed magnetite. However, relaxation was delayed in macrophages exposed to silica (positive controls). The release of intracellular LDH enzyme activity to the extracellular space was negligible in cells exposed to toner compared with negative and positive controls. Morphological examinations by light and electron microscopy revealed no abnormal findings in the exposed cells. A histochemical study using TUNEL staining and the electrophoretic profile of DNA obtained from cells exposed to toner and to silica were negative for apoptosis. The results of the present and other investigations into animal exposure indicate that photocopier toner is toxicologically inert. However, although the present study examined only effects in vitro, exposure to toner should be minimized because lung overloading in animals has been reported.

To show distinct evidence of the pseudo-blindsight caused by electromagnetic stimulations in order to reveal a cure for lost visual functions, it is necessary to investigate the differences from the usual optic pathway in terms of the data processing route from the electromagnetically stimulated retina. For elucidating the scheme of phosphenes like blindsight, we designed a new stimulus coil system and measured the hemodynamic responses in the occipital regions during the stimulations, employing a functional brain-imaging technique. Results showed the possibility that the phosphene as a pseudo-blindsight induces activation of a parietal association area by an alternate route without the primary visual cortex and can be expected as therapy for lost visual functions.

Alveolar macrophages are thought to play an important role in fibrogenesis in the lungs caused by various types of exposure to dust. In this experiment, we evaluated the effect of silicon carbide whiskers (SiC) on alveolar macrophages mainly by unique magnetometry and also by established methods such as lactate dehydrogenase (LDH) activity, apoptosis measurement and morphological observations. Alveolar macrophages obtained from Syrian golden hamsters by bronchoalveolar lavages were exposed in vitro to Fe3O4 for 18 hours as an indicator for magnetometry and SiC for experiments. A rapid decrease of the remanent magnetic field, so called "relaxation", was observed after cessation of an external magnetic field in macrophages phagocytizing Fe3O4 alone, while relaxation was delayed in those concurrently exposed to SiC. Release of LDH from SiC-exposed macrophages into the medium was not significantly higher than the controls, but it increased dose-dependently. Apoptosis was recognized in macrophages exposed to 60 micrograms/ml of SiC by the DNA ladder detection method and morphological observations. Electron microscopic examination revealed irregular forms of nuclei and organellas in macrophages exposed to SiC. Magnetometry, LDH release and electron microscopic observation indicated mild cytotoxicity of SiC to alveolar macrophages.

Gallium arsenide (GaAs), a chemical compound of gallium and arsenic, causes various toxic effects including pulmonary diseases in animals. Since the toxicity is not completely investigated, GaAs has been used in workplaces as the material of various semiconductor products. The present study was conducted to clarify the toxicity of GaAs particles in the alveolar macrophages of hamsters using magnetometry, enzyme release assays and morphological examinations. Alveolar macrophages obtained from hamsters by tracheobronchial lavage and adhered to the disks in the bottom of wells were exposed to ferrosoferric oxide and GaAs particles. Ferrosoferric oxide particles were magnetized externally and the remanent magnetic field was measured. Relaxation, a fast decline of the remanent magnetic fields radiated from the alveolar macrophages, was delayed and decay constants were decreased dose-dependently due to exposure to GaAs. Because the relaxation is thought to be associated with cytoskeleton, the exposure of GaAs may have impaired the motor function of them. Enzyme release assay and morphological findings indicated the damage to the macrophages. Thus the cytotoxicity causes cytostructural changes and cell death. According to DNA electrophoresis and the TUNEL method, necrotic changes occur more frequently than apoptotic changes.

The Japanese language has three writing systems: kanji script, or ideograms, hiragana script, or phonograms and katakana script, another type of phonograms. Modern Japanese has 71 hiragana and 71 katakana characters, which have one-to-one correspondence. A hiragana character has only one phonetic value, which represents a mora, or a syllable, in spoken Japanese. A recent positron emission tomography (PET) study [1] reported that overt reading of words written in hiragana activated bilaterally the medial and lateral occipital gyri, the posterior inferior temporal areas, Heschl’s gyri, the posterior inferior frontal areas (including Broca’s area), and the supplementary motor area. In addition, unilateral activation was seen in the left basal ganglia and the right thalamus. This PET study, however, did not reveal the temporal dynamics of the hiragana reading process. We thus attempted to follow the spatiotemporal activation sequence of cortical signals while subjects read hiragana.

Alveolar macrophages are thought to play an important role in fibrogenesis due to asbestos exposure. In this experiment, we evaluated the effect mainly by unique magnetometry and also by conventional methods such as lactate dehydrogenase (LDH) activity measurement and morphological observations. Alveolar macrophages obtained from Syrian golden hamsters by bronchoalveolar lavages were exposed 18 hours in vitro to Fe3O4 as an indicator for magnetometry and chrysotile for experiments. A rapid decrease of the remanent magnetic field, so called “relaxation”, was observed after the cessation of an external magnetic field in macrophages phagocytizing Fe3O4 alone, while relaxation was delayed in those concurrently exposed to chrysotile. Since relaxation is thought due to the cytoskeleton-driven random rotation of phagosomes containing iron oxide particles, chrysotile is considered to interfere with the cytoskeletal function of macrophages. Release of LDH from chrysotile-exposed macrophages into the medium was recognized, but it was not significantly higher than the controls. Apoptosis was negligible in macrophages exposed to chrysotile by the DNA ladder detection, the terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling method and morphological observations. Electron microscopical examinations revealed early necrotic changes in macrophages exposed to chrysotile. These findings indicate that cell magnetometry detects impaired cytoskeletal function due to in vitro exposure to chrysotile.