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Biomedical subjects

M Kiyosawa

Publications and source records attributed to M Kiyosawa.

At least 37 records · Page 2Linked to original sources
PubMed1996

Functional neuroanatomy of visual object naming: a PET study.

BACKGROUND: The ability to name objects depends partly on visual perception. We used positron emission tomography (PET) to measure activity-related changes in regional cerebral blood flow (r-CBF) in order to identify regions of the brain activated during visual object naming. METHODS: Four right-handed volunteers were recruited. Following an intravenous injection of 15O-labeled water, r-CBF was measured during visual object naming, counting numbers, and resting. PET and MRI images were coregistered, the size of the brain was proportionally adjusted in each axis to Talairach's and Tournoux's atlas, and the comparison of stimulated versus resting blood flow images revealed activated brain regions. RESULTS: In the subtraction of resting from naming, activation was observed in the bilateral primary visual cortex, bilateral fusiform gyrus, left lingual gyrus, bilateral inferotemporal cortex, bilateral inferior frontal gyrus, bilateral precentral gyrus, anterior cingulate gyrus, left parietal operculum, and left putamen. In the subtraction of counting from naming, most of the those areas were activated, but no significant activity was observed in the left lingual gyrus, left parietal operculum, or bilateral precentral gyrus (motor cortex). The areas activated with the paradigm included those dedicated to visual perception (primary and associate visual cortex), visual recognition (inferior temporal cortex), and phonological output (Broca's area). CONCLUSION: Our results indicated that the major neural network from occipital lobe to frontal cortex, which is mainly involved in the ventral visual pathway, demonstrated activation in these tasks. Result of this study will serve as base line data for analyzing the findings in patients with impaired visual perception.

Adult↗
PubMed1996

Synthesis and evaluation of 5-HT3 receptor antagonist [11C]KF17643.

For imaging CNS 5-HT3 receptors by PET, a high affinity 5-HT3 receptor ligand, endo-8-methyl-8-azabicyclo[3.2.1]oct-3-yl 2-(n-propyloxy)-4-quinolinecarboxylate (KF17643), have been labeled with 11C. N-Methylation of the desmethyl compound with [11C]methyl iodide followed by HPLC separation produced [11C]KF17643 with the decay-corrected radiochemical yield of 19-28%, the specific activity of 7.5-49 GBq/mumol and the radiochemical purity of > 99% at 35-40 min from EOB. After i.v. injection of [11C]KF17643 into mice, it was taken by the brain at a high level and was stable for metabolism, but no sign for the 5-HT3 receptor selectivity was found in the brain tissues by the tissue sampling and autoradiography, probably because of large non-specific binding. The [11C]KF17643 was not suitable as a PET ligand for mapping the CNS 5-HT3 receptors.

Animals↗
PubMed1996

Positron emission tomography in diagnosing brainstem vascular lesions that cause abnormal eye movements.

PURPOSE: To evaluate the efficacy of positron emission tomography (PET) in aiding in the diagnosis of brainstem infarctions that cause abnormal eye movements. METHOD: Cerebral glucose metabolism was examined by PET with 18F-fluorodeoxyglucose as a tracer in five normal control subjects and six patients with abnormal eye movements. The PET images were registered to and superimposed on magnetic resonance images (MRIs). RESULTS: All control subjects showed little asymmetry of glucose metabolism in the brainstem, whereas all six patients demonstrated areas of low glucose metabolism in the brainstem. Areas of low metabolism seen by PET were wider than they appeared to be by MRI; MRIs even appeared normal in some patients. Asymmetry index measurements at the level of the ischemic lesion ranged between 19% and 45%. CONCLUSIONS: Positron emission tomography detected metabolic abnormality in patients with brainstem lesions that caused abnormal eye movements. Superimposing PET images on MRIs accurately localized abnormally low metabolism in the brainstem. Combined imaging with PET and MRI can be used to diagnose ischemic lesions in the brainstem from functional (PET) and morphologic (MRI) viewpoints.

Adult↗
PubMed1996

Unilateral eyeball enucleation differentially alters AMPA-, NMDA- and kainate glutamate receptor binding in the newborn rat brain.

The aim of the present work was to evaluate the neurochemical effects of early unilateral visual deprivation as a model of impaired visual maturation. For this purpose, binding to the different ionotropic glutamate receptor subtypes was quantified in vision-related and vision-unrelated brain structures of control and unilaterally deprived newborn rats. At post-natal (PN) day 10, male Sprague-Dawley rats underwent either unilateral eyeball enucleation (enucleation group, n = 12) or sham operation (control group, n = 12). In each group, brains were obtained either at post-natal day 20 (n = 6) or post-natal day 30 (n = 6) and processed for quantitative in vitro autoradiography selective for NMDA, kainate, and AMPA glutamate-binding sites, as well as for the presynaptic adenosine A1 receptor as a control of the deafferentation efficacy. In control animals, quantitative autoradiography revealed an increase in NMDA (e.g. +45% in superior colliculus) and kainate receptor binding (e.g. +55% in visual cortex, layer IV) from post-natal day 20 to post-natal day 30, associated with stable levels of AMPA receptor binding, in the vision-related structures. In the deafferented visual structures, monocular enucleation induced a marked decrease in A1 site density (e.g. -38 to -52%, in the superficial layer of superior colliculi, at PN day 20 and PN day 30, respectively) in parallel with a mild increase in both NMDA (e.g. +8 to 9%, in superior colliculi and visual cortex, layer IV at PN day 30, respectively) and AMPA (e.g. +16%, in layer IV of the visual cortex at PN day 30). Superimposed on marked bilateral decreases at PN day 30 in the enucleated rats, kainate receptor binding also revealed a slight but significant decrease (-5%) in the deafferented superior colliculus as compared to the non-deafferented side. The present findings (different time-courses of, and differential effects of deafferentation on, the NMDA, kainate and AMPA glutamate receptor subtypes throughout the visual brain structures) further support the involvement of these receptors in distinctive roles during maturation of the visual system.

Animals↗
PubMed1996

Carbon-11-labeled KF15372: a potential central nervous system adenosine A1 receptor ligand.

UNLABELLED: The carbon-11-labeled selective adenosine A1 antagonist KF15372 ([1-propyl-11C]8-dicyclopropylmethyl-1,3-dipropylxanthine) was elevated in vivo as a PET ligand for mapping CNS adenosine A1 receptors. METHODS: The regional brain distribution of [11C]KF15372 and the effects of adenosine antagonists on the distribution were determined in mice by tissue sampling. In rats, in which the retinal projection fibres to the superior colliculus had degenerated due to unilateral eye removal, the brain distribution of [11C]KF15372 was visualized by ex vivo autoradiography. RESULTS: The mouse brain uptake of [11C]KF15372 was 1.8% i.d./g at 5 min and then it gradually decreased. The uptake was high in the hippocampus, cerebral cortex, striatum and cerebellum, and was significantly reduced by A1 antagonists but not by A2 antagonists. The brain distribution of 11C assessed by the tissue sampling and autoradiography was compatible with that of the A1 receptors. Autoradiography clearly visualized unilaterally decreased A1 receptor binding in the superior colliculus. CONCLUSION: The results demonstrated that [11C]KF15372 is a selective and high-affinity adenosine A1 receptor ligand and is useful for detecting the degeneration of presynaptic neurons.

Animals↗
PubMed1995

[Incidence of acute idiopathic optic neuritis and its therapy in Japan. Optic Neuritis Treatment Trial Multicenter Cooperative Research Group (ONMRG)].

Data on the incidence of and treatment for acute idiopathic optic neuritis were obtained by questionnaire sent to departments of ophthalmology, university hospitals, and general hospitals throughout Japan. Inquiry was made as to the number of cases which developed idiopathic optic neuritis from April 1992 to March 1993 along with their clinical features. The response rate was 53.6%. There were a total of 550 cases, and the male to female ratio was 1:1.22. Patients 14 to 55 years old were 65.9%; bilateral involvement: 28.2%; recurrence: 18.6%; positive past history of the other eye; 7.5%. Assuming the answering rate to be 100% and two thirds of the patients to be included, annual incidence of this disease (the annual number of patients) was determined to be 1.62 for an adult population of 100,000 (1.03 cases/100,000 people). Tochigi, Tokyo, Kanagawa, Hyogo, Wakayama, Okayama, Yamaguchi, Tottori, Shimane, Ehime, and Fukuoka showed an annual incidence exceeding 2.0/100,000 adults. At more than 95% of all medical institutions questioned, patients with optic neuritis were usually treated with systemic corticosteroids. Oral corticosteroid therapy, which was shown in a recent study in USA to be contraindicated, was still being used at 15% of the institutions.

Acute Disease↗
PubMed1995

Effect of kanji and kana reading on cerebral blood flow patterns measured by PET.

To investigate the respective functions of pathways in processing visual information from different types of symbols, by positron emission tomography (PET) we examined the effect on cerebral blood flow (CBF) of reading the Japanese morphogram (kanji) versus the syllabogram (kana). Nine Japanese men were presented with three visual conditions in random order 2 minutes before the scan: eyes open controls, kanji morphogram reading, and kana syllabogram reading. Three words written in kanji or kana were shown, and subjects were instructed to read them silently and to identify the word unrelated logically to the other two. The reading and analyzing tasks activated wide areas of vision-related cortices. The comparison of the kanji and kana readings showed higher metabolism, with the former only in the posterior part of the primary visual cortex. Most of the CBF increases were common for both stimuli, although the patterns of these increases differed slightly. The correlation matrix of CBF change in the left hemisphere showed a ventral connection in kanji reading and a dorsal connection in kana reading. Our results suggest there is a functional differentiation in the brain between patterned and sequential perception when reading Japanese morphograms and syllabograms.

Adult↗
PubMed1994

Marked increase in [3H](R) alpha-methylhistamine binding in the superior colliculus of visually deprived rats after unilateral enucleation.

The binding of [3H](R)alpha-methylhistamine to histamine H3-receptors in visual structures of unilaterally enucleated rats was examined by quantitative autoradiography to clarify the involvement of histamine neurons in the visual system. [3H](R)alpha-Methylhistamine binding in the visually deprived superior colliculus, contralateral to the enucleated eye, was significantly increased 5, 15, 30 and 45 days after unilateral enucleation. Slight time-dependent increases in ligand binding were observed in the visual cortex, but the change was significant only 45 days after unilateral enucleation. Unilateral enucleation had no significant effect in the dorsal lateral geniculate nucleus at any time after enucleation. Continuous injection of (S)-alpha-fluoromethylhistidine, a specific inhibitor of L-histidine decarboxylase, attenuated the effect of unilateral enucleation in the superior colliculus. These results suggest that retinal deafferentation induced an increase in histamine H3-receptor binding sites, probably by selective adjustment of histamine neurons in response to unilateral enucleation.

Animals↗
PubMed1994

Successfully treated optic nerve infiltration with adult T-cell lymphoma.

A 45-year-old woman with adult T-cell leukemia had a sudden onset of decreased vision with central scotoma in the right eye. Right optic disc edema and thickening of the optic nerve were observed by magnetic resonance imaging. A diagnosis of leukemic infiltration to the optic nerve was made. A course of oral corticosteroid therapy was prescribed and 40 Gy of radiation was administered to the whole brain and right orbit. Her visual acuity recovered from finger counting to 20/20 within 3 weeks. We believe that this patient represents the first report of successfully treated optic nerve infiltration with adult T-cell leukemia caused by human T-lymphotropic virus type-I infection.

Female↗
PubMed1993

Conjunctival malignant melanoma with xeroderma pigmentosum.

A 10-year-old male patient with xeroderma pigmentosum had a recurrent, pigmented, conjunctival tumor. Conjunctival malignant melanoma was diagnosed from the histopathological examination of the resected biopsy specimens. To our knowledge, this case of conjunctival malignant melanoma in a patient with xeroderma pigmentosum may be the second such report in the literature. We believe that malignant melanoma must be considered with squamous cell carcinoma in the differential diagnosis of conjunctival tumors in patients with xeroderma pigmentosum. Fontana-Masson and S-100 staining techniques helped diagnose this conjunctival malignant melanoma.

Child↗
PubMed1993

Recurrence of nanophthalmic uveal effusion.

A patient with nanophthalmic uveal effusion had a recurrence 7 months after the initial sclerectomies and sclerostomies. The effusion was cured by repeating the procedure. Specimens obtained at the first operation showed interlacing collagen lamellae and thin collagen bundles with an electron-dense deposit in the perifibrillar space. Specimens from the second operation showed disarranged collagen bundles with closely packed thin collagen fibrils. Collagen lamellae were not found. The regenerated scleral tissue was thought to interfere with the transscleral outflow and to block the bypass route, thus resulting in the recurrence of uveal effusion.

Exudates and Transudates↗
PubMed1993

Retinal changes in myotonic dystrophy. Clinical and follow-up evaluation.

Retinal changes in myotonic dystrophy include butterfly-shaped pigmentary changes in the macula, reticular pigmentary retinal changes in the midperiphery, and peripheral atrophic polygonal-shaped changes. To assess the prevalence and progressiveness of these changes in a large series, 49 patients with myotonic dystrophy were examined. Of the eyes studied, 26 (26.6%) had butterfly-shaped macular pigmentary changes, 24 (24.5%) had reticular pigmentary retinal changes, and 43 (43.9%) had peripheral atrophic polygonal-shaped changes. Ten patients (18 eyes) had two different types at once. Visual acuity was not severely affected. Electroretinographic examination showed diminished a and b wave amplitudes in eyes with and without retinal changes. Arden ratios on the electrooculogram were normal in 13 of 14 patients tested. During the follow-up period, which exceeded 5 years, 3 of 9 patients had newly developed or enlarged, patterned changes of the pigment epithelium. These results suggest that pigmentary retinal changes in patients with myotonic dystrophy are slowly progressive.

Adolescent↗
PubMed1992

Spontaneous orbital hemorrhage in adult females. A report of three cases.

Three cases of spontaneous orbital hemorrhages in 3 adult females are reported. All of the patients had acute radiating pain in the orbit, vomiting and proptosis with a limitation of motility and ecchymosis of the eyelids. One was due to a large orbital varix with a preceding history of intermittent exophthalmos; the causes of the other cases could not be determined from their backgrounds. Within a few weeks, all of them had recovered from hematoma and had good prognoses without surgery. Orbital venous bleeding with 40 mm Hg pressure will cause more than 500 g tension on the four rectus muscles. To treat this clinical emergency, hemostasis with compression in the early phase and waiting for its spontaneous absorption are recommended.

Adult↗
PubMed1992

Intraorbital ophthalmic artery aneurysm: case report.

A rare case is presented of a nonruptured aneurysm of the intraorbital ophthalmic artery in which successful resection of the aneurysm resulted in improvement of preoperative progressive signs caused by the mass effect of the aneurysm. The surgical management of this rare entity is discussed with special attention given to the collateral circulation of the ophthalmic artery from the external carotid artery.

Aneurysm↗
PubMed1992

[A case of chronic progressive external ophthalmoplegia with Oguchi's disease].

A 52-year-old case of chronic external ophthalmoplegia accompanied by Oguchi's disease was reported. The patient noticed night blindness and deafness since childhood. Later he developed ocular movement limitation to all directions by the age of 40. He had 20/20 corrected visual acuity and normal anterior segment, as well as normal color vision. Goldmann's perimetry showed generalized constriction of the peripheral field. Golden tapetal reflex without dark adaptation disappeared after 4 hours of dark adaptation, i.e. Mizuo-Nakamura's phenomenon was recognized. Recovery of diminished a and b wave electroretinogram to the subnormal range was also observed after 4 hours of dark adaptation. Rod-cone interaction test revealed a monophasic adaptation, and no suppression to the cones from the rods was observed. This finding was also compatible with Oguchi's disease. ECG revealed incomplete atrio-ventricular as well as right bundle branch blocks. Neurological examination findings were entirely normal other than slight enhancement of deep tendon reflexes in the lower extremities and mixed typed difficulty of hearing. Muscle biopsy of the right medial rectus muscle revealed ragged-red fiber, suggesting mitochondrial abnormalities. Never the less the quadriceps femoris muscle biopsy specimen showed normal histological findings. This is the first case report of progressive external ophthalmoplegia associated with Oguchi's disease. Mitochondrial abnormality was confirmed only in the external ocular muscle. This case may be a variant of Kearns-Sayre syndrome.

Humans↗