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Positron beam facilities are widely used for solid state physics and material science studies. A positron beam facility has been constructed at the Kyoto University Research Reactor (KUR) in order to expand its application range. The KUR is a light-water-moderated tank-type reactor operated at a rated thermal power of 5 MW. A positron beam has been transported successfully from the reactor to the irradiation chamber. The total moderated positron rate was greater than 1.4 × 10 6 /s while the reactor operated at a reduced power of 1 MW. Special attention was paid for the design of the in-pile position source to prevent possible damage of the reactor in case of severe earthquakes.

We describe an effective, versatile technique for reconstructing the electric conductivity distribution from magnetic vector field measurements. Using magnetic vector field data measured over a region of interest (ROI), the assumed steady current vector field is reconstructed to perform conductivity reconstruction. As the current sources/current flow outside the ROI significantly contribute to magnetic fields over the neighbourhood of the ROI border, the extra contributions are reduced in the measured magnetic field data using a derived spatial weight function. The remaining magnetic field measurement errors are coped with utilizing a mollification method in conjunction with a regularization method. In a straightforward manner, our current field reconstruction technique is combined with our previously reported conductivity reconstruction technique. The combined non-contact conductivity reconstruction technique in principle allows handling of an arbitrary geometry of the target conductive ROI and arbitrary current sources existing outside the ROI. The technique is particularly effective when an inherent current flow exists and only field measurements are needed. Technique feasibility is simply verified by reconstructing a 2D conductivity distribution using simulated, noise-filled, magnetic field data. Resultant reconstructions indicate the technique to be a practical means for robustly reconstructing target conductivity distributions.

1 Department of Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan 2 Institute of Materials Structure Science, KEK, 1-1 Oho, Tsukuba, Ibaraki, Japan 3 Institute of Particle and Nuclear Studies, KEK, 1-1 Oho, Tsukuba, Ibaraki, Japan 4 Advanced Meson Science Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama, Japan 5 Department of Physics, Korea University, 145, Aman-ro, Seongbuk-gu, Seoul, 137-713, Korea 6 Department of Physics, Tokyo University of Science, 1-3, Kagurazaka, Sinjuku-ku, Tokyo, Japan

Objective: The aim of this study was to investigate the signal intensity characteristics of highly invasive and highly metastasizing transplanted human squamous cell carcinoma using ultra-small super-paramagnetic iron oxide (USPIO)-enhanced MRI and to correlate them with USPIO distribution to tumour components revealed by histological examination. Methods: 13 nude mice with transplanted human squamous cell carcinoma in the oral cavity were imaged before and 24 hours after intravenous administration of USPIO. The difference in signal intensity between pre-contrast and post-contrast MR images was visually evaluated. For quantitative analysis, signal intensity within a region of interest was measured. Histological findings were correlated with MR findings. The approximate USPIO concentration was evaluated using USPIO phantoms. Results: Seven tumours had an area showing signal intensity increase on post-contrast T1 weighted images. Histopathologically, six of those tumours contained a small amount of iron particles in the stroma. The USPIO concentration was presumed low. Two tumours had an area showing signal intensity decrease on post-contrast T1 and T2 weighted images. The areas had a large amount of iron particles in the stroma and the USPIO concentration was presumed high. There was a minimal amount of iron particles in tumour parenchymal cells. Conclusions: The amount of USPIO accumulation into tumour stroma was considered to affect MR signal intensity. A small amount increases T1 weighted signal intensity, whereas a large amount decreases T1 and T2 weighted intensity. The USPIO accumulation into the tumour parenchyma was not thought to affect MR signal intensity. Dentomaxillofacial Radiology (2012) 41, 55–63. doi: 10.1259/dmfr/28673011

Um dos fatores que influencia diretamente no desempenho de sistemas mecanizados é a velocidade de deslocamento pela sua importância no planejamento e na execução das operações agrícolas. O objetivo deste trabalho foi avaliar a acurácia de quatro sensores de velocidade, em condições de superfície asfáltica, solo com cobertura vegetal, aclives e declives, acelerações e desacelerações, submetidos a velocidades representativas para aplicações agrícolas. Foram ensaiados dois modelos comerciais de sensores de radar, um sensor de GPS e um sensor óptico. Foram identificadas diferenças significativas para as situações de solo com cobertura vegetal, acelerações e desacelerações. Para a superfície asfáltica, em situação de velocidade constante, os sensores avaliados não apresentaram desempenho com diferença significativa. Os sensores tipo radar demonstraram ser influenciados pela superfície com cobertura vegetal. Na superfície asfáltica, sob condições de aceleração e desaceleração, o sensor de GPS apresentou retardo nos valores de velocidade quando comparado com os demais. One of the factors that influence directly the performance of mechanized systems is the forward speed that is important on planning and managing agricultural operations. The objective of this work was to evaluate the accuracy of four speed sensors, on paved road, vegetated surface, hills, increasing and reducing representative speeds for agricultural applications. Two commercial radars, a GPS sensor and an optical sensor were tested. For the paved road surface, under constant speed, no significant differences were observed on the performance. Radars were influenced by the vegetated surface. On paved road and under acceleration and deceleration the GPS sensor presented delay on its speed values when compared with the other sensors.

We proposed a technique for reconstructing bio-electric conductivity distribution from measured tangential magnet field data. That is, in the 2D ROI with an arbitrary depth two orthogonal tangential components of 3D current vector field were respectively estimated from the synthetically measured two tangential magnetic fields, from which the 2D conductivity distribution was estimated. To cope with inevitable measurement errors, a robust numerical solution was developed, in which the mollification method and the regularization method were efficiently utilized. By performing this 2D reconstruction at each depth, 3D conductivity distribution could be estimated. As typical applications, pathological state and/or bio-electric conductive path can be evaluated by monitoring the temporal change of the reconstructed 3D conductivity distribution. The feasibility of this technique was briefly verified by reconstructing a conductivity distribution using simulated noise-filled magnetic field data, with resultant reconstructions indicating that the approach could provide a practical means for robustly reconstructing a conductivity distribution.

A positron beam facility is presently under construction at the Kyoto University Research Reactor (KUR), which is a light-water moderated tank-type reactor operated at a rated thermal power of 5 MW. A cadmium (Cd) - tungsten (W) source similar to that used in NEPOMUC was chosen in the KUR because Cd is very efficient at producing γ-rays when exposed to thermal neutron flux, and W is a widely used in converter and moderator materials. High-energy positrons are moderated by a W moderator with a mesh structure. Electrical lenses and a solenoid magnetic field are used to extract the moderated positrons and guide them to a platform outside of the reactor, respectively. Since Japan is an earthquake-prone country, a special attention is paid for the design of the in-pile positron source so as not to damage the reactor in the severe earthquake.

A 37-year-old woman was admitted to the hospital with the complaint of progressive horizontal diplopia of six years' duration when viewing distant objects. On admission she had a slight left convergent strabismus. Homonymous diplopia was present beyond 50 cm and increased on distance fixation. Both eyes were fully mobile in the horizontal plane with a mild decrease in the velocity of horizontal eye movement to the left, and slight impairment of upward eye movement. The left eye did not fully adduct during convergence. The right pupil was slightly larger than the left. Prism cover test showed 6 delta esophoria at 30 cm and 14 delta esophoria at 5 m. The Hess chart showed a convergent deviation. MRI revealed a small right-side paramedian lesion of the midbrain tegmentum lying ventral to the aqueduct of Sylvius, at the level between the superior colliculi and the intercollicular area. A venous angioma with arteriovenous shunts in the right midbrain was diagnosed by angiography. We suggest that lesions that damage the divergence neurons in the tegmentum of the midbrain and also interrupt the supranuclear fibers having an inhibitory effect on the convergence neurons may produce homonymous diplopia on distant fixation combined with the esotropia.

A 36-year-old woman presented an inability to ingestion and mild hemiparesis with superficial and deep sensory disturbances on the left side for two months after a stroke. Dysphagia was originated from bilateral cricopharyngeal spasm, which was disclosed by videofluorography, manometry at the pharyngo-esophageal segment, and needle electromyography. Although no focal lesion of the brain was detected even with MRI, neurological and electrophysiological findings suggested that the lesion was localized to the lower pontine and mudullary tegmentum on the right side. Two months after the onset, botulinum toxin (10 units) was administered into the bilateral cricopharyngeal muscles, which resulted in restoration of the normal swallowing function in 5 days, and the normal function is lasting 5 years. Botulinum toxin therapy is non-invasive and effective for cricopharyngeal spasm. This non-invasive method will be the first choice for cricopharyngeal spasm replacing surgical intervention.

Medial medullary infarction is characterized by ipsilateral hypoglossal nerve palsy with contralateral hemiparesis and disturbance of deep and discriminative sensory perception. We examined the extent and distribution of disturbances in deep sensation and compared the findings with the lesion location in the medial lemniscus detected by MRI in 3 patients with medial medullary infarction. We classified the lesion location into 2 groups; type I and type II. Type I was ventral to the middle medial lesion of the medial lemniscus, and type II was ventral to the dorsal medial lesion. In our series, type I (Case 1) impairment of the three kinds of deep sensations was more severe in the lower extremities than in the up-per extremities. In type II (Cases 2, 3) the severity or impairment in the upper extremities was moderate or severe and nearly equal to that in the lower extremities. There was no difference in the severity of impairment for the four kinds of discriminative sensations. In the literature, type I (8 patients) impairment of position sense in deep sensation was found in 1 of 7 patients in the upper extremities and 5 of 7 patients in the lower extremities. Impairment of vibration sense was found in 1 of 7 patients in the upper extremities and in all patients in the lower extremities. In type II (14 patients) severe impairment of position and vibration sense in deep sensation was found in 3 patients in the upper extremities equal to that in the lower extremities. There was no tendency in the severity of impairment of four kinds of discriminative sensations. Including our 3 cases and 22 in the literature, impairment of deep sensation was more severe in the lower extremities than in the upper extremities in type I (9 patients) and the extent was none (7), mild or moderate (2) in the upper extremities, mild (2), moderate (1), severe (2), obscure (4) in the lower extremities, while in type II (16 patients) the severity in the upper extremities was nearly equal to that in the lower extremities and the extent was none (1), mild or moderate (1), severe (5), obscure (9) in the upper extremities, none (2), mild or moderate (1), severe (6), obscure (7) in the lower extremities. It is concluded that hemiparesis appeared with lesions located in the pyramidal tract of the medulla, hemiparesis and disturbance of deep sensation in the upper and lower extremities, predominantly in the lower extremities with the lesion of the pyramidal tract to the middle of medial lemniscus in the medulla, hemiparesis and disturbance of the upper and lower extremities deep sensation with lesions of the pyramidal tract to the whole of the medial lemniscus in the medulla. Evaluating deep sensation of the upper and lower extremities is useful for speculation of the lesion location in the medial lemniscus in medial medullary infarction.

Our previous study showed that the alternating knee tilt test in supine position is a useful method to assess the trunk rigidity. We investigated the progression of axial (neck and trunk) rigidity in Parkinson's disease (PD), striatonigral degeneration (SND), and progressive supranuclear palsy (PSP) by using this method. We assessed rigidity on a scale of 0 (absent) to 3 (severe) on five parts of the body: neck, trunk, wrist, elbow and knee in 57 patients with PD, 13 patients with SND and 18 patients with PSP. In PD patients, the degree of neck and trunk rigidity correlated well with the duration of disease and the staging scale. There was neck rigidity in 27% of PD patients with unilateral involvement of the limbs, but the trunk tonus was normal in them. There was rigidity in the neck and trunk of all PD patients with bilateral involvement of the limbs. When the limb rigidity was predominant on one side, the trunk rigidity was predominant on the opposite side. In SND patients, the degree of neck and trunk rigidity roughly correlated with the duration of disease and the staging scale. In SND patients with unilateral involvement of the limbs, tonus of the neck and trunk was normal. In SND patients with bilateral involvement of limbs, there was rigidity in both the neck and the trunk. In PSP patients, the degree of neck rigidity correlated well with the duration of disease and the staging scale, but the degree of rigidity in the trunk and limb remained relatively mild even at the advanced stage. Accordingly, in PSP patients there was a dissociation of the degree of neck rigidity from that of trunk and limb rigidity. In conclusion, the assessment of axial (neck and trunk) rigidity may be useful for the clinical diagnosis of parkinsonism and the staging scale scoring.

Decerebrate spasm is a generalized muscular spasm produced by some stimuli on decerebrate posture. Such spasm are called "tonic fit" or "decerebrate extensor spasm". We reported a 50-year-old man with periodic decerebrate spasm after cerebral hemorrhage. On admission, the patient was comatose. The pupils were round but anisocoric and did not react to light. Corneal reflexes were absent. The face, arms, and legs did not move voluntarily. Two weeks after admission, he was found in decerebrate rigidity. Periodic decerebrate spasms were also observed and were accompanied by ocular dipping. Cheyne-Stokes respiration, and hypersympathetic activity (transiently dilated pupils, hypertension, tachycardia). These symptoms persisted for two months and were induced by painful or sonic stimuli and suppressed by sleep, sedative or antiedematous drugs. The cycle was 0.6 approximately 0.7 per minute in accord with that of Cheyne-Stokes respiration. Magnetic resonance imaging revealed an area of low signal intensity in the midbrain to the bottom of the pons caused by the tentorial herniation on T1-weighted images. From the the clinical features and results of MRI studies, we considered that dysfunction of the midbrain to the pons in addition to diffuse cerebral dysfunction played some role in the manifestation of periodic decerebrate spasm with ocular dipping.

We studied the correlation between neuroradiological findings and pathological observations of white matter lesions in a patient with frontal type adrenoleukodystrophy. A 41-year-old man developed schizophrenic symptoms and generalized convulsions at the age of 40. Examination revealed baldness, loss of the axillary hair, stereotypical behavior, mutism, dysphagia echographia, right hemiparesis, and brisk reflexes in all four limbs with bilateral extensor plantar responses. Blood examination revealed a high concentration of very-long-chain fatty acids in plasma; the patient was diagnosed as having adrenoleukodystrophy. His condition continued to worsen, and gradually he became akinetic. He died of pneumonia at the age of 43. T1- and T2-weighted MR images distinguished three abnormal zones in the cerebral white matter in this case. In the first zone (Z1), the signal intensity was moderately high on T2-weighted images and slightly low on T1-weighted images; this zone was not enhanced with Gd-DTPA. In the second zone (Z2), the signal intensity was slightly high on T2-weighted images, while moderately low on T1-weighted images; Z2 was enhanced with Gd-DTPA. In the third zone (Z3), the signal intensity was markedly high on T2-weighted images and low on T1-weighted images; Z3 was not enhanced with Gd-DTPA. Z3 was located in the frontal pole; Z2 and Z1 were consecutively located in rostro-caudal fashion in the brain. The subsequent pathological study of the brain of this patient revealed the following findings: Z1 showed destruction of myelin with axonal sparing, Z2 showed numerous lipid-laden macrophages, demyelinated axons, and a vigorous perivascular mononuclear cell response, Z3 consisted of a dense mesh of glial fibrils and scattered astrocytes without any evidence of an active process. In this study, the correlation between MR images and pathological findings in adrenoleukodystrophy was clearly established. Single photon emission tomography with 99mTc-hexamethylpropyleneamine oxime, and positron emission tomography with 15O2 continuous inhalation technique showed a reduction in the regional cerebral blood flow (rCBF) and in the regional cerebral metabolic rate of oxygen (rCMRO2) in the cerebral cortex near the Z1 and Z3. A normal or slight increase of rCBF and a reduction of r CMRO2 was found in the cerebral cortex near the Z2. Coronal MR images showed that Z3 was located in the deep white matter, while Z2 and Z1 were consecutively located in an inner-outward fashion, suggesting that the demyelination process started in the cingulum and spread in an inner-outward fashion and progressed in rostro-caudal manner.

Truncal rigidity is regarded as a cause of axial motor disturbances such as difficulty in turning around and in rising from a recumbent position in parkinsonism. However, methodology for clinical evaluation of truncal rigidity has not yet been established. This study aims at developing a suitable bed-side technique to evaluate truncal rigidity in parkinsonism. Forty normal adults and fifty-one patients with Parkinson's disease or juvenile parkinsonism were examined. We tried to evaluate truncal tonus by twisting the subjects' body axis in a supine position. The subjects' axis was passively rotated by the examiner supporting and twisting the subjects' (1) shoulder, (2) axillas, (3) hips, and (4) knees. In comparing these four procedures, the maximal rotation of the axis was obtained easily with twists supporting the knees, that is alternating tilts of the bending knees rightward and leftward in a supine position. By this method of alternating knee tilts, the examiner felt merely a little resistance in twisting the normal subjects. On the other hand, in patients with parkinsonism, a considerable degree of resistance against twists was elicited, and the patients' side-was passively elevated from a bed in accordance with knee tilts. Electrical activities of the truncal muscles (M. erector spinae, M. obliquus abdominis externus and internus) during the alternating knee tilts were studied in ten normal adults and seventeen parkinsonian patients. Continuous electrical activities were present in the axial muscles, particularly at the thoracic level, which were passively stretched by this procedure in parkinsonism but never present in normals.(ABSTRACT TRUNCATED AT 250 WORDS)

We report a 52-year-old male patient with Shy-Drager syndrome (SDS) complicated by an occurrence of the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). The patient first developed impotence at the age of 48, accompanied by urinary incontinence, and episodes of dizziness while standing. The following year, the patient had developed a staggering gait and speech became monotonous. At age 52, the patient was admitted to the hospital after experiencing frequent episodes of syncope associated with complete loss of consciousness. Upon examination, blood pressure was 100/70 in a recumbent position, and 80/60 when standing. The pulse rate varied from 60 per minute to 62. The patient was alert. The alternating Horner sign was observed, and a paucity of facial movements was visible. His speech was slow and monotonous. Muscle tone was increased bilaterally. There was incoordination. A laboratory examination revealed reduced serum sodium levels of 127 mEq/L and increased sodium excretion with plasma hypoosmolality (262 mOsm/kg/H), urine hyperosmolality and low serum renin activity (0.2 ng/ml/h). Renal functions were normal and the levels of adrenocortical and thyroid hormones were normal. There were no abnormalities observed in the chest roentgenogram taken. The level of antidiuretic hormone (ADH) was unreasonably high (5.74 pg/ml). A water-load test demonstrated failure of both water diuresis and inhibition of ADH secretion. These data suggested that hyponatremia in this case was caused by SIADH. The correlation between plasma osmolality and the concentration of ADH suggested that osmolality that initiates ADH release appeared to have been reset to around 230 mOsm/kg lower than normal.(ABSTRACT TRUNCATED AT 250 WORDS)

This report is concerning a case of acute spontaneous paralysis of the posterior interosseous nerve (P.I.O.N.), possibly caused by twists in the nerve trunk, in a 23-year-old woman. The subject felt a tingling pain over the lateral epicondyle of the right forearm when grasping and lifting a basin, and noticed that the fingers of the right hand could not be extended three days later. The fingers of the left hand also experienced paralysis 3 months after the first injury when she pronated and extended left forearm. Neurological examination revealed bilateral P.I.O.N. paralysis. When, after a period of time, the bilateral P.I.O.N. paralysis had not improved, surgical exploration of both P.I.O.N. was performed. It revealed that the right P.I.O.N. underwent a severe constriction at 2 cm proximal to the superficial portion of the supinator muscle, and that the proximal portion of the right nerve was swollen. The constricted portion of the right nerve was resected 5 mm in length, and nerve suturing was performed. The left P.I.O.N. was also constricted at the same location, and was found to be a sausage-like neurinoma with two constrictions. In the histological examination of the right resected P.I.O.N., edema of the interstitial tissue and a great number of regenerating cluster formations, including swollen axons, were observed proximal to the constriction. Distal to this, severe Wallerian degeneration was found. These histological findings were the same as those of chronic compression neuropathy. The authors reviewed and analysed reports on 20 other cases of P.I.O.N. paralysis that had compressions at 2 cm proximal to the superficial portion of the supinator muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

We reported a patient with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), presenting localized radiculopathy as an initial symptom. The patient, a 38-year-old man, developed muscle atrophy of right shin and calf. In April 1988, neurological examination revealed decreased superficial sensation and muscle atrophy in right L-4 distribution. MRI of the lumbar spinal cord and myelography were negative. In April 1989, he was admitted to Chiba University Hospital. There were slight weakness of right ankle extension and flexion, muscle atrophy of bilateral shin and calf (that of the right leg was more marked), decreased sensation of polyneuropathy type in all modalities and generalized hypo- or a-reflexia. Nerve conduction study revealed marked prolongation of F response and focal conduction block in various site. The CSF was acellular and total protein was 177 mg/dl. Sural nerve biopsy disclosed decreased number of large myelinated fibers and scattered thin myelinated fibers. This case indicates that CIDP may present localized radiculopathy in early phase and is important to point out various mode of onset among CIDP.

Two cases of cervical myelopathy, which exhibited peculiar vasomotor symptoms ("acro-erythro-cyanosis") on distal regions of the four limbs are reported. Continuous reddening, swelling and skin temperature increase were observed on both hands and feet in case 1, a-44-year-old man, and on both hands in case 2, a-47-year-old man. Cold stimulation resulted in cyanosis and decrease of skin temperature on the affected regions paroxysmally. The condition of skin at room temperature may be caused by arteriectasia of arterioles due to hypotonia of vasomotor fibers, and this was similar to erythromelalgia. On the other hand, cold stimulation may have led to this condition, where the contraction of skin arterioles due to hypertonia of vasomotor fibers was added to the dilation of venule, and this was similar to acrocyanosis. Consequently, we provisionally named the vasomotor symptoms in the present cases as "acro-erythro-cyanosis". The other neurological signs were as follows. Case 1: mild weakness in right upper and lower limbs and left small hand muscles, mild superficial and deep sensory disturbance on bilateral palms and soles and decrease of vibration on bilateral lumbar regions and thereunder. Case 2: mild weakness of right small hand muscles, superficial sensory disturbance on distal regions of bilateral upper and lower limbs and a decrease of joint position sense on right hand. Myelography and metrizamide CT myelography revealed a high-degree deformity of the spinal cord due to the herniated disks between C4 and C5 in case 1 and between C3 and C4 in case 2.(ABSTRACT TRUNCATED AT 250 WORDS)

5,5-Dimethylcyclohexane-1,3-dione and its derivatives were shown to isomerize to give 5,6-dihydropyran-4-ones on irradiation in FSO3H or 98% H2SO4. The 2,2-dimethyl derivative, lacking hydrogen on C2, failed to give any products under the same conditions. A similar type of isomerization was also observed with thiolane-2,4-dione and its derivatives, while no photoisomerization was observed with their nitrogen or oxygen analogs. A possible reaction mechanism is proposed.

The visible absorption spectra of the cross-sections of the dyed various synthetic-polymer fibres were measured by means of a microspectrophotometer. We found that the spectra of Acridine Orange hydrochloride in the crosssections of fibres showed a maximum of α-band and β band, and the spectra of Acridine Orange (free base), indicated a maximum of α-band, β-band and the crystal peak of the dye. These results suggest that the monomeric state, the aggregate as well as the crystal of the dye exist in these dyed synthetic-polymer fibres.

The visible absorption spectra of the cross-section of dyed PVA fibre with AO were measured by means of a microspectrophotometer. The spectra showed a high maximum at 475 nm, which would be referred to as β-band (a monomer peak at 498 nm). Many void places were recognized in core layer by electron or scanning electron microscopy. It was explained that the dimer band mainly arose from dye aggregates or crystals at the void places of fibre.

The visible absorption spectra of dye crystals and the cross-section of the polyvinyl alcohol fibre dyed with Acridine Orange as free base were measured by means of a microspectrophotometer. The spectra of crystals show a sharp and high maximum at 450 nm which will be referred to as the peak from dye crystals. The spectra of the cross-section of dyed fibre show three peaks of 443 nm (crystals-band), 470 nm (β-band) and 499 nm (α-band). These results suggest that crystals, aggregates and monomer of the dye exist within the dyed polyvinyl alcohol fibre.

Ethylenediaminetetraacetate (EDTA)-dependent pseudothrombocytopenia, in vitro platelet clumping and consequent pseudothrombocytopenia in the presence of EDTA, was observed in a patient with thymoma-associated myasthenia gravis (MG). The patient, a 45-year-old man, presented with alopecia areata, and weakness and fatigue of right upper extremity and neck muscles. Diagnosis of MG was made on the basis of positive edrophonium test and antiacetylcholine receptor (AChR) antibody test. The platelet count was as low as 4.9 X 10(4)/mm3 in EDTA-anticoagulated blood and large agglutinates were seen in smears from EDTA blood. Platelet suspension immunofluorescence test showed IgG on the surface of platelet clumping. Corticosteroid therapy combined with thymectomy reduced the platelet clumping markedly in parallel with decrease of anti-AChR antibody titers. The present observation suggests that EDTA-dependent pseudothrombocytopenia in our patient was associated with some immunological abnormalities. Recognition of the pseudothrombocytopenia in MG patients is important to distinguish it from idiopathic thrombocytopenia purpura which is also found in MG and requires bone marrow tests and sometimes splenectomies.