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Biomedical subjects

T Okuno

Publications and source records attributed to T Okuno.

At least 469 records · Page 26Linked to original sources
PubMedDate not supplied

Scanning electron microscopy of the liver cell cytoskeleton.

Rat livers were perfused with 0.5% Triton X-100 for 30 to 60 min and studied by scanning electron microscope. Three-dimensional filamentous networks were visualized in the cytoplasm of hepatocytes in situ. Branching and end-to-side contacts of intermediate filaments, and intermediate filaments which were connected with microtubules and microfilaments were noted. Numerous filaments were observed in the perinuclear region and at the cell border. Filaments were attached to polyribosomes and nuclei. No differences were observed in the cytoplasmic cytoskeleton after treatment of the sample at 4 degrees C. These results support the concept that intermediate filaments mechanically integrate the cytoplasmic space.

Animals↗
PubMedDate not supplied

Serum 2',5'-oligoadenylate synthetase activity during interferon treatment of chronic hepatitis B.

We measured 2',5'-oligoadenylate synthetase activities in serum and peripheral blood mononuclear cells from 10 patients with chronic hepatitis B who were being treated with interferon so as to determine whether 2',5'-oligoadenylate synthetase activity in serum reflected 2',5'-oligoadenylate synthetase activity in peripheral blood mononuclear cells, and whether it could be used to monitor interferon treatment. Pretreatment values of 2',5'-oligoadenylate synthetase activity in patients' serum and peripheral blood mononuclear cells were not statistically different from values from control subjects. When interferon was administered, serum levels of 2',5'-oligoadenylate synthetase began to rise within 3 hr, reached peak values at 12 hr and then declined. The levels of 2',5'-oligoadenylate synthetase activity both in serum and peripheral blood mononuclear cells increased substantially during interferon treatment, ranging 2- to 50-fold greater than initial levels. The levels of 2',5'-oligoadenylate synthetase in serum correlated closely with levels in peripheral blood mononuclear cells. In addition, when the levels of 2',5'-oligoadenylate synthetase rose during interferon administration, serum hepatitis B virus DNA polymerase values fell, and, in some cases, DNA polymerase rose again when 2',5'-oligoadenylate synthetase fell after discontinuation of interferon. These findings suggest that 2',5'-oligoadenylate synthetase activity in serum accurately reflects the antiviral effect of interferon and could be used to monitor interferon treatment.

2',5'-Oligoadenylate Synthetase↗
PubMedDate not supplied

Regional cerebral blood flow in diagnosis of childhood onset partial epilepsy.

We compared regional cerebral blood flow assessed by [123I]N-isopropyl-p-iodoamphetamine (IMP) single-photon emission tomography (SPECT) with magnetic resonance imaging (MRI), computed tomography (CT) and interictal surface electroencephalography (EEG) to evaluate its diagnostic potential in 24 patients with partial seizures with onset in childhood. Focal low uptake areas were observed on SPECT scans of 18 patients and were presumed to represent epileptogenic areas in 17. MRI revealed an abnormality in 12 and CT in 6 patients, and all organic lesions showed SPECT abnormalities, too. Six patients without focal structural abnormalities showed regional perfusion deficit on SPECT. Routine scalp EEG revealed an epileptic focus in 17 patients and three of them showed discordant results between SPECT and EEG, which suggested more serious brain disorders. In two patients without EEG localization only SPECT showed focal abnormalities in the probable epileptic area. [123I]IMP-SPECT was useful in locating the epileptic focus, particularly during the early period after the onset of partial seizures when the EEG gave inconclusive results.

Adolescent↗
PubMedDate not supplied

123I-IMP SPECT findings in mitochondrial encephalomyopathies.

We performed N-isopropyl-[123I]p-iodoamphetamine (IMP) single photon emission computed tomography (SPECT) in three patients with Leigh syndrome, two patients with mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS), and two siblings with progressive external ophthalmoplegia (PEO). The SPECT images were compared with the findings on magnetic resonance imaging (MRI) and computed tomography (CT). All Leigh syndrome patients showed low accumulation areas (LAA) bilaterally in the frontal lobes and the basal ganglia. The frontal lobe LAA was seen even in an area without abnormalities on CT/MRI. Each MELAS patient showed a focal LAA. SPECT could also detect an old stroke-like lesion that was no longer shown by CT/MRI. However, SPECT did not show LAA in the basal ganglia, which showed calcification on CT or abnormal signal intensity on MRI. MRI in the 2 PEO patients showed lesions bilaterally in the basal ganglia in one, and in the internal capsules in the other. SPECT showed LAA not only in corresponding areas, but also in the occipital lobes, where no lesions were revealed by MRI. Thus, 123I-IMP SPECT was more sensitive than CT/MRI for detecting stroke-like lesions in MELAS patients, although it did not detect small lesions in the basal ganglia. LAA in the frontal lobes and occipital lobes may be SPECT findings characteristic of Leigh syndrome and PEO, respectively.

Adolescent↗
PubMedDate not supplied

Indication for anti-epileptic drug treatment of benign childhood epilepsy with centro-temporal spikes.

To approach the problem concerning whether or not anti-epileptic treatment of benign childhood epilepsy with centro-temporal spikes (BCECT) is necessary, we retrospectively studied 6 untreated and 39 treated patients with BCECT and compared their clinical findings after 2 years of observation. Then we selected 6 untreated and 28 treated patients from the same series who had been free from attacks for more than 2 years to determine whether the mode of onset (multiple seizures or isolated one for the first month of the illness) was related to the duration of active epilepsy in these two groups. This comparative study of untreated and treated patients followed for 2 years revealed no differences in the interval between first visit and start of attack-free period between the two groups. The mean duration of active epilepsy in those with only isolated seizures at onset was significantly shorter than that in those with multiple seizures at onset. Anti-epileptic medication may be unnecessary in patients with isolated seizure during sleep; it does not affect the natural course of BCECT. Treatment is necessary for a longer period in patients with multiple seizures at onset than in those with isolated seizures at onset.

Anticonvulsants↗
PubMedDate not supplied

Acute hemiplegia syndrome in childhood.

Three types of clinical features at the onset are well known to be characteristic of acute hemiplegia syndrome (AHS). Type 1 comprises status epilepticus of hemiconvulsions with fever. Representative diseases of this type are the infectious diseases of the central nervous system, acute encephalopathy and cerebral vascular diseases. Type 2 comprises status epilepticus of hemiconvulsions without fever. Cerebral vascular diseases and epilepsy are the major ones of this type. Type 3 comprises hemiplegia or hemiparesis of sudden onset without fever or convulsions. Most patients with this type had cerebral vascular diseases, about half of which were moyamoya disease in Japan. Recent progress in neuroimaging studies has allowed considerable elucidation of the etiology of AHS. Gadolinium-enhanced MRI showed minimal lesions such as capsular infarction more clearly than plain MRI. Acetazolamide test 99mTc-HMPAO SPECT imaging is one of the useful assisted diagnostic techniques for moyamoya disease, because it reveals the reserve capacity of the collaterals. [123I]IMP SPECT is useful for the diagnosis and follow-up of acute disseminated encephalomyelitis (ADEM), as the images of the lesions coincide well with the MRI ones. 99mTc-HMPAO SPECT in a case with alternating hemiplegia revealed normoperfusion in the ictal periods. Four cases of AHS are reported here.

Acute Disease↗
PubMedDate not supplied

An MRI study of the myelination pattern in West syndrome.

Using magnetic resonance imaging (MRI), we studied the myelination of the brains of 8 patients with West syndrome. All cases were symptomatic, 2 having severe asphyxia, 1 lissencephaly, 1 Leigh encephalopathy, 2 tuberous sclerosis, 1 multiple anomalies and 1 microcephaly. Myelination of the pons, cerebellum, thalamus, internal capsules, optic radiation, centrum semiovale and cerebral white matter was separately assessed. The 2 cases with tuberous sclerosis exhibited normal myelination patterns, although asymmetry of the cerebral white matter was noted. These cases had a moderate degree of mental retardation and persistent seizures. The other 6 cases exhibited a marked delay of myelination throughout the central nervous system except for the midbrain. These cases had severe psychomotor retardation and persistent seizures. Although the difference in the outcome may simply reflect the different etiological disorders, these results suggest that the myelination pattern is related to the psychomotor retardation but not to the severity of the seizures in West syndrome. Atrophy of the corpus callosum developed during ACTH therapy and disappeared after the therapy. It was thus suggested that the callosal atrophy caused by the ACTH therapy was reversible.

Atrophy↗
PubMedDate not supplied

Acute hemiplegia in childhood with the occlusion of the posterior cerebral artery.

Two cases of acute hemiplegia with the occlusion of the posterior cerebral artery were reported in children. Both patients were low-birth-weight infants with a history of febrile convulsions. Cerebral edema due to prolonged seizures was considered to be an etiologic factor of the occlusion of posterior cerebral artery. When the seizure is focal or the patient has perinatal difficulty, febrile convulsions should be treated carefully, as the possibility of epilepsy exists.

Brain Edema↗