Biomedical subjects

K Mizokami

Publications and source records attributed to K Mizokami.

At least 19 recordsLinked to original sources

PubMed2001

[An operated case of bitemporal lobe epilepsy associated with old infarction in the left occipital lobe].

A 15-year-old female, who presented with bitemporal lobe epilepsy associated with old infarction in the left occipital lobe, was reported. MRI with fluid attenuated inversion recovery sequence demonstrates cortical atrophy with hyperintensity of the white matter in the left occipital lobe as well as volume loss and hyperintensity of the left hippocampus. Interictal positron emission tomography with [18F]fluorodeoxy glucose (FDG-PET) and single photon emission computed tomography with technetium-99m-ethyl-cysteinate dimer indicate hypometabolism and hypoperfusion in the left occipital lobe and the left temporal lobe, respectively. Scalp recorded EEG did not lateralize the side of the epileptogenic zone. Chronic subdural electrode recording demonstrated that the ictal onset zones were located in the bilateral side of the temporal lobe. Eighty-nine percent of 19 spontaneous seizures were left sided onset. The anterior temporal lobectomy with hippocampectomy was performed for the left side. Although temporal lobe epilepsy is sometimes a bilateral disease, unilateral lobectomy for a strong predominant side, based on the MRI and FDG-PET findings, is effective for some patients.

Adolescent↗

PubMed2001

[Brain stem hemorrhage associated with venous angioma: report of two cases].

The incidence of hemorrhage associated with venous angioma has been considered to be rare. We here report two cases of brain stem venous angioma which also showed brain stem hemorrhage. Case 1; a 15-year-old female had experienced weakness in the left upper extremity 8 months prior to admission. She developed dysfunction of the left cranial nerves, and magnetic resonance imaging (MRI) showed a huge enlarging hematoma in the pons. Cerebral angiography showed venous angioma penetrating through the pons. Evacuation of the hematoma was performed through the fourth ventricle and many small vessels were found in the hematoma. Although all symptoms were partially resolved after the operation, a re-hemorrhage occurred 1 month after the operation. Case 2; a 50-year-old man had suddenly developed headache and vertigo several days prior to admission. Computed tomography (CT) and MRI showed a small hematoma in the lesion with venous angioma adjacent to the hematoma. All symptoms gradually resolved with conservative therapy.

Adolescent↗

PubMed2000

[Small epidermoid induced trigeminal neuralgia unrecognized by conventional CT and MRI for over 25 years].

A 65-year-old woman had been conservatively treated as idiopathic trigeminal neuralgia for over 25 years, because conventional computed tomography (CT) and magnetic resonance imaging(MRI) showed no abnormality in the cerebello-pontine(CP) angle cistern. She received a detailed MRI by constructive interference in steady state and diffusion weighted image(DWI) sequences. Those sequences on MRI well demonstrated a epidermoid tumor in the CP angle cistern, and the removal of the tumor completely resolved the neuralgia. Since a small epidermoid in the CP angle cistern seems to be unrecognized by conventional CT and MRI, detailed evaluation by DWI sequence, which has been widespread recently, is required for patients with trigeminal neuralgia.

Aged↗

PubMed1997

[Effect of topical carteolol on visual function in normal-tension glaucoma].

The effects of carteolol hydrochloride on visual function in normal-tension glaucoma (NTG) were investigated. 22eyes of NTG patients were divided into two groups, i.e., (1) a group receiving topical application of 2% carteolol hydrochloride b.i.d. and 2 an unmedicated group. During a 18 month period, intraocular pressure and visual field (measured by Humphrey automated perimetry) were measured every 3 months, and the measurements obtained in the two groups were compared. Analysis of the results revealed a considerable reduction in intraocular pressure in the carteolol group as compared with the control group. The progression of mean deviation tended to be less in the carteolol group, but the intergroup difference in this respect was not statistically significant. However, increase in corrected pattern standard deviation was clearly less pronounced in the carteolol group than in the control group. These results supported the conclusion that carteolol is effective in inhibiting deterioration of the local visual field. This is attributed to increased ocular perfusion due to diminished intraocular pressure, as well as an inhibitory effect upon vasoconstriction in the optic nerve head due to intrinsic sympathomimetic activity, preventing decrease in papillary blood flow and adverse effects upon ocular circulation.

Administration, Topical↗

PubMed1994

[Comparison of a trabeculotomy and trabeculectomy combined with phacoemulsification and foldable lens implantation].

Combined phacoemulsification, foldable lens implantation, and trabeculotomy (12 eyes, LOTOMY group) or trabeculectomy (22 eyes, LECTOMY group) were performed. At 6 months after the operation the visual acuity improvement (over 0.5 improvement, 83.3% in the LOTOMY group, and 95.5% in the LECTOMY group) was not significantly different between the two groups. 9 months postoperatively ocular pressure values (15.6 +/- 3.0 mmHg in the LOTOMY group, and 14.2 +/- 8.0 mmHg in the LECTOMY group) were not significantly different between the two groups. But within 7 days postoperatively average values of the maximal ocular pressure (25.5 +/- 5.9 mmHg in the LOTOMY group, and 11.8 +/- 3.0 mmHg in the LECTOMY group) were significantly higher in the LOTOMY group. The value was higher than the preoperative level. In the follow-up, progressive visual field loss was seen in 17% of the cases in the LOTOMY group. There was no progressive visual field loss in the LECTOMY group. Especially in cases with advanced glaucomatous visual field loss, the occurrence of ocular pressure spikes in the initial postoperative period may be closely related to postoperative progressive visual function loss. Phacotrabeculectomy was effective in avoiding these spikes.

Aged↗

PubMed1993

[Changes in optic disc rim color with glaucomatous visual field damage--a quantitative study on pattern of color changes].

We developed a new computerized method for measuring the color of the optic disc directly with objective reproductivity. We compared the optic disc color with sensitivity loss in visual fields corresponding to the disc area measured by Humphrey Field Analyzer. 11 normal eyes, 40 glaucomatous eyes, and 27 eyes with ocular hypertension were studied. In the temporal segment of the disc rim, with the exception of the area, a significant correlation between rim color and sensitivity loss was detected. In the nasal rim and macular area, however, the correlation was less significant in early stage glaucoma. Compared with normal discs, glaucomatous discs showed significant decrease in the red color element of the rim area, and some discs with ocular hypertension showed a decrease without any visual field defect.

Aged↗

PubMed1991

[The development of human trabecular meshwork].

The fetal development of the trabecular meshwork of the human eye was quantitatively studied by light and electron microscopy. From the 20th fetal week onward, the progressive thickening of the trabecular meshwork was achieved mainly by the widening of intertrabecular spaces, whereas the thickness and the number of trabeculae were almost constant. Significant alterations in the number of trabecular meshwork cells did not occur with development. However, a decrease in trabecular meshwork cellularity occurred by the widening of intertrabecular spaces. As development proceeded, there was an increase in the proportion of the width of the posterior trabecular meshwork, which is the main site of aqueous drainage, in accordance with the increase of aqueous production.

Cell Count↗

PubMed1991

Epidemiology of glaucoma in Japan--a nationwide glaucoma survey.

A population-based, collaborative glaucoma survey was conducted in seven regions throughout Japan, during the years of 1988 and 1989. The total number of subjects examined was 8,126 out of 16,078 residents aged 40 years or older, representing a participation rate of 50.54%. There were no significant differences in background factors between participants and randomly sampled nonparticipants. A mainstay of the screening consisted of tonometry and fundus photography with nonmydriatic camera, followed by automatic perimetry as a recall examination. Overall prevalences obtained were primary open-angle glaucoma (POAG) 0.58%, low-tension glaucoma (LTG) 2.04%, primary angle closure glaucoma (PACG) 0.34%, other types of glaucomas 0.60%, and ocular hypertension (OH) 1.37% at the time of screening. The very high prevalence of LTG and extremely low prevalence of OH in the Japanese might reflect a racial peculiarity in the age-specific trend of the intraocular pressure. The prevalence of PACG was found much higher in Japanese than in Caucasians, with a predilection for women. Racial peculiarities as revealed in this study were discussed, with particular reference to the refractive status in the Japanese that showed progressive decrease in myopia with age.

Adult↗

PubMed1991

[A comparative study of optic disc appearances in progressive and non-progressive low-tension glaucoma].

The relation between the optic disc appearances and the progression of visual field defects was studied by retrospective case review of 148 eyes of 74 patients with a diagnosis of low-tension glaucoma (LTG). Visual fields were tested by a Goldmann perimeter and the subjects were divided into two groups, i.e. 43 eyes (29.1%) with progression and 105 eyes (70.9%) without progression, according to Esterman's scale. In the group which showed progression, mean IOP (p less than 0.05), level of change in IOP and maximum of IOP (p less than 0.01) were significantly higher. No differences were observed in any of the following parameters: prevalence of peripapillary hemorrhage or crescent, rim pallor, disc/arteriole ratio, number of rim-crossing vessels. Mildly hypoplastic disc, however, was statistically more frequent in the progressive group (p less than 0.05). The authors suspect that not only IOP but some inherent factors concerning the optic nerve head may play an important role in the progression of LTG.

Glaucoma↗

PubMed1991

[The development of the Schlemm's canal in human eyes].

The fetal development of Schlemm's canal of the human eye was investigated by light and electron microscopy. Schlemm's canal was not yet a circumferential structure at the 20th fetal week, and at the 26th fetal week the canal appeared to form by a process of confluence of the channels. As development proceeded, the canal positioned relatively anterior to the apex of the angle, as a result of posterior shift of the angle recess. The remarkable increase in the width of the canal during the fetal period was mainly achieved by the elongation of the endothelial cells, whereas the number of endothelial cells in meridional sections did not alter. From the 26th fetal week onward, the frequency of giant endothelial vacuoles and pores increased together with the discontinuity of the basal lamina, which corresponds with the increase of aqueous flow.

Endothelium↗

PubMed1991

[A comparative study on visual field defect in low tension glaucoma].

The mode of visual field defect and the change of intraocular pressure (IOP) were analyzed between progressive low tension glaucoma (LTG) and non-progressive LTG. Maximum IOP and phasic fluctuation in IOP during the follow-up period in progressive cases were significantly higher than those in non-progressive cases (p less than 0.01). This greater range in phasic fluctuation may lead to the development of glaucomatous damage. Analysis of the pattern of visual field defect revealed significantly greater frequency of dense defects within 10 degrees of the fixation area in progressive cases. Another analysis on the mode of visual field damage between progressive LTG and POAG demonstrated higher frequency of focal progression of the damage. These results suggest that there are some different etiological factors among progressive LTG, non-progressive LTG and POAG, while focal anatomical weakness at the optic nerve head also influences the development of damage in some case of progressive LTG.

Glaucoma↗

PubMed1990

Aflatoxin B1-specific cytochrome P-450 isozyme (P-450-AFB) inducible by 3-methylcholanthrene in golden hamsters.

Hepatic microsomes of polychlorinated biphenyl (PCB)-treated Syrian Golden hamsters possessed a higher potency toward aflatoxin B1 activation, based on the Ames test, than other animal species. This activity was induced in hamsters preferentially by treatment with 3-methylcholanthrene rather than phenobarbital. The contribution of an isozyme of cytochrome P-450 (P-450-AFB) to the activity of hamster livers for aflatoxin B1 was studied. P-450-AFB, purified from 3-methylcholanthrene-treated hamster livers, was shown to possess the highest activation of aflatoxin B1 in the Ames test. The quantification of this isozyme by a fluorometric sandwich enzyme-linked immunosorbent assay (ELISA) demonstrated that P-450-AFB was induced mainly in Syrian Golden hamsters but not in Chinese hamsters, or in other species. This isozyme constitutes approximately 40% of the total cytochrome P-450 of the hepatic microsomes from 3-methylcholanthrene-treated Golden hamsters but only 1% in the microsomes of phenobarbital-treated hamsters. Thus, we conclude that the high activity of Golden hamster livers towards aflatoxin B1 activation was due presumably to this distinct and unique cytochrome P-450 isozyme which was induced mainly by 3-methylcholanthrene in Golden hamsters.

Aflatoxin B1↗

PubMed1990

[Retinal ganglion cell topography during prenatal development].

A fundamental feature of the human visual system is nonuniform distribution of ganglion cells across the retinal surface. In adults, the density of ganglion cells peaks around the fovea and declines sharply towards the periphery, whereas in fetal retina it does not. In the fetal retina, the retinotopic map is dominated by nonuniform expansion and/or ganglion cell death. We examined how the numbers and distributions change according to the horizontal eccentricity from the foveola, using toluidine blue stained vertical sections of the human fetal retina (gestational age 32W and 40W). The vertical section of the fovea showed almost similar density at 32 weeks, 40 weeks and in adults. This fact suggested that the fundamental structure of the fovea is already established at 32W. In the nasal retina, the cellular density was higher than that in the temporal half at 32W, then markedly decreased at 40W and in adults. We assume that in the nasal retina, it is impossible to account for the cell decrease only with nonuniform expansion and that even after 32W ganglion cell death occurs. On the other hand, in the mid-temporal retina, the cellular density was almost similar at 32W, 40W and in adults. It suggested that in the mid-temporal retina, the topography is already established at 32W. In the peripheral temporal retina, the cellular density was relatively high at 32W and decreased at 40W and in adults. In this area, the topography is still changing. We assume that in the fetal retina, retinotopic map is dominated by several factors and the dominant factor differs according to stage and retinal area.

Cell Count↗

PubMed1990

[Progression of early glaucomatous visual field defects].

We studied the mode of progression of visual field defects in glaucoma the using static computerized perimetry (OCTOPUS 201). As a result of analysis using Delta Program, the modes of progression of the visual field defects were divided into two groups, general depression and local depression. The cases of general depression were younger than those of local depression. In cases of local depression, we examined the direction of progression in isolated scotomas. Isolated scotomas located at the nasal visual field tended to progress toward the nasal and peripheral side.

Adult↗

PubMed1989

Complete cDNA sequence of a major 3-methylcholanthrene-inducible cytochrome P-450 isozyme (P-450AFB) of Syrian hamsters with high activity toward aflatoxin B1.

Cytochrome P-450AFB is major isozyme inducible by 3-methylcholanthrene in Syrian golden hamsters and shows high potency toward aflatoxin B1 activation. We have isolated and sequenced cDNA clones to P-450AFB by immunoscreening a hamster liver cDNA library in lambda gt11. The longest clone contains an open reading frame of 1482 nucleotides and encodes a protein of 494 amino acids with a molecular weight of 57,420. The sequence of P-450AFB shares a 73% and 65% homology with that of mouse P-450 15 alpha (IIA3) and rat P-450a (IIA1), respectively, indicating that P-450AFB is a unique gene of the P-450IIA subfamily. The apparent concentration of a mRNA species hybridizable to the clone as well as the concentration of a protein immunoreactive to P-450AFB was increased significantly by the treatment with 3-methyl-cholanthrene, which indicates that the increase in P-450AFB protein is due mainly to an elevation of the mRNA.

Aflatoxin B1↗

PubMed1989

Characterization of three forms of cytochrome P-450 inducible by 3-methylcholanthrene in Golden hamster livers with special reference to aflatoxin B1 activation.

Three forms of cytochrome P-450 of liver microsomes of 3-methylcholanthrene-treated Golden hamsters were purified and characterized as regards their catalytic activity toward aflatoxin B1-related hepatocarcinogenic mycotoxins. These include two major forms, designated as cytochrome P-450-AFB (P-450-I) and P-450-II, and one minor form, P-450-III. Cytochromes P-450-AFB, P-450-II, and P-450-III have their absorption maximum in the carbon monoxide-complex of the reduced form at 448.5, 447.0, and 448.0 nm, have apparent molecular weights of 56,000, 58,000, and 59,500, and are in the low spin, high spin, and low spin state, respectively. Of these, cytochrome P-450-AFB was shown to be highly active in the mutagenic activation of aflatoxin B1-related hepatocarcinogens such as sterigmatocystin and O-methylsterigmatocystin. Activation of aflatoxin B1 by hepatic microsomes of 3-methylcholanthrene-treated hamsters was inhibited almost completely by the antibody against P-450-AFB but not by the antibody against P-450-II, indicating that P-450-AFB is the major component responsible for the activation of aflatoxin B1 by hamster liver. Western blot analysis demonstrated that no protein cross-reacted with the antibody to P-450-AFB in the liver microsomes from guinea pig, rat, mouse, and house musk shrew (Suncus murinus) treated with 3-methylcholanthrene, while one or two proteins cross-reacted with the antibody to P-450-II in the liver microsomes of these animals.

Aflatoxin B1↗

PubMed1989

[Studies on diameter distribution of axons in the optic pathway in human glaucoma].

The distribution of diameters of axons and somas at the level of the optic nerve, lamina cribrosa and retina were compared between human glaucomatous eye and normal control eyes. At the level of lamina scleralis of the glaucomatous eye, there was a tendency for large nerve fibers to be lost in the arcuate nerve fiber area particularly in the inferior arcuate nerve fiber area, where the corresponding visual field defect was detected. The percentages of large axons and somas in the arcuate nerve fiber area decreased in the glaucomatous eye both at the level of the optic nerve, retina but most of all at the level of lamina cribrosa. These results suggest that the mode of optic nerve damage in early glaucoma is characterized by the selective damage of large nerve fibers, which is most severe at the lamina cribrosa.

Axons↗

PubMed1989

[Contributory factors for glaucomatous disc cupping. 4. Generalized expansion type and localized type].

It is widely recognized that there are two types progressive disc cupping in glaucoma. One of them is the localized type (L type) in which the cupping extends to a certain direction and the other is the generalized expansion type (G type) in which the cupping expands generally. We evaluated the optic disc in 86 eyes with primary open angle glaucoma (G type 44 eyes L type 42 eyes) to evaluate correlations of age and visual field defects between the 2 groups. Our study revealed that G type patients were significantly younger than those with L type when matched according to visual field defects. We also found that G type was revealed as the nasal step alone but not in L type. These results suggest that in G type, the optic nerve head is diffusely damaged by elevated intraocular pressure and the total nerve fibers are destroyed uniformly. On the other hand, in L type, the vulnerable portion of the optic nerve head is selectively damaged and nerve fibers constituting the optic rim area are destroyed. As a result, L type is likely to form cupping notch and reveal Bjerrum scotoma. These facts correspond to the anatomical structures of nerve fiber layers.

Adult↗