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Biomedical subjects

Y Miyake

Publications and source records attributed to Y Miyake.

At least 523 records · Page 29Linked to original sources
PubMed1987

Analysis of kinetic rate constants in [18F]fluorodeoxyglucose model using a least square fitting package SALS (statistical analysis with least squares).

The analysis of kinetic rate constants in the compartment model for [18F]fluorodeoxyglucose (FDG) was undertaken. Four kinetic rate constants were determined with a least square fitting package SALS (Statistical Analysis with Least Squares), using the measured data of 18F activity as a function of time. SALS calculations were found to be easy and quick with high precision. The rate constants and the curves fitted by the k3 and the k4 models were compared in situations with various degree of cerebral glucose metabolism during positron emission tomography (PET) studies. The k4 model in the determination of cerebral metabolic rate for glucose (CMRglu) was much superior than the k3 model in any given situation as it always underestimates the metabolic rate. However, the k3 model produces less variation when the cerebral radioactivity curve shows steady rising pattern.

Brain↗
PubMed1987

Purification and characterization of glucosyltransferase from Streptococcus mutans OMZ176 with chromatofocusing.

A crude glucosyltransferase (GTase) preparation of Streptococcus mutans OMZ176 was fractionated by chromatography on a chromatofocusing column. It was separated into three major fractions. Fractions 1 and 3 mainly synthesized water-soluble glucan (SG) without primer dextran T-10. Dextransucrase activity of fraction 1 was not increased by the primer, although that of fraction 3 was increased. Fraction 2 synthesized only water-insoluble glucan (IG) in the absence of a primer, but mutansucrase activity of this fraction was greatly increased dose-dependently by the addition of a primer. The SG and IG synthesized by fraction 1 were rich in alpha-1,6 glucosidic linkages. On the other hand, about 80% of glucose residues of the IG synthesized by fraction 2 were alpha-1,3 linked. Both SG and IG synthesized by fraction 3 contained highly branched structures.

Chromatography, Gel↗
PubMed1987

On- and off-responses in photopic electroretinogram in complete and incomplete types of congenital stationary night blindness.

The on- and off-responses of photopic electroretinogram (ERG) were recorded by rectangular light stimuli in 13 patients with complete type and 9 patients with incomplete type of congenital stationary night blindness. The positive on-response (b-wave) was significantly smaller in both types than in normal subjects (P less than 0.001). The rapid off-response was normal in complete type patients, but was significantly smaller in incomplete type patients than in normal subjects (P less than 0.001). Since the rapid off-response mainly reflects the decay of the late receptor potential of the cones, incomplete type patients may have a visual disturbance in the cone itself. Normal rapid off-response with abnormal on-response in complete type patients suggests the existence of a photopic visual disturbance in the middle retinal layer. These results strongly suggest that these two types of congenital stationary night blindness have a different pathogenesis in the photopic visual pathway.

Adolescent↗
PubMed1987

Characteristic ERG-flicker anomaly in incomplete congenital stationary night blindness.

Ten patients with the incomplete type of congenital stationary night blindness (CSNB) were examined with a 30 Hz flicker electroretinogram (ERG). After 30 min of dark adaptation, 30 Hz flicker ERG was recorded continuously for 12-15 min under white background illumination. All patients showed an exaggerated increase of amplitude and a universal characteristic change of wave shape as the light adaptation progressed. Thirty normal subjects also showed increased amplitude during light adaptation, but the increase in amplitude was significantly less than in incomplete-type CSNB, and there was little change in wave shape. The same procedure was applied to patients with complete-type CSNB, retinitis pigmentosa, congenital retinoschisis, cone dystrophy, and Oguchi's disease; neither the exaggerated increase of amplitude nor the wave change was seen. Our results indicate that incomplete-type CSNB is a newly identified cone-rod dysfunction syndrome with a special functional property.

Electroretinography↗
PubMed1987

Indomethacin and the epinephrine-induced breakdown of the blood-ocular barrier in rabbits.

Using aqueous and vitreous fluorophotometry, the authors examined the blood-aqueous and blood-retinal barrier functions in three groups of pigmented rabbits. Epinephrine (1.25%) was applied topically five times daily and indomethacin (0.5% sesame oil suspension) was applied topically three times daily to one eye of each of the animals in Group 1; under the same regimen, epinephrine and indomethacin placebo were administered to one eye of each of the animals in Group 2 and epinephrine placebo and indomethacin placebo were administered to one eye of each of the animals in Group 3. Fluorophotometry was done 1, 2, and 3 months after drug administration. The results showed that epinephrine induced disruption of the blood-aqueous barrier 2 and 3 months after drug administration, and that the magnitude of this disruption increased with time. Epinephrine also induced disruption of the blood-retinal barrier 3 months after drug administration. Indomethacin significantly prevented disruption of the blood-aqueous barrier at 2 and 3 months and significantly prevented disruption of the blood-retinal barrier at 3 months. The magnitudes of the barrier disruptions in eyes treated with both epinephrine and indomethacin were slightly higher than, or the same as, those of the control eyes. The results strongly indicated that the epinephrine-induced disruption of the blood-ocular barrier was partially caused by prostaglandins and other cyclo-oxygenase products whose biosynthesis was initiated by epinephrine.

Animals↗
PubMed1987

Activation mechanism of human urinary prokallikrein using trypsin as a model activator.

Rapid release of a small peptide from human urinary prokallikrein by trypsin resulted in activation of the prokallikrein. The peptide was identified as the propeptide of the kallikrein from its amino acid sequence. Two large disulfide-linked peptides were also produced very slowly, which accompanied the increase in kallikrein activity. The molecular weights of the two peptides were roughly estimated to be 18,000 and 25,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). N-Terminal amino acid sequences were determined as Ile-Val-Gly-Gly-Trp-Glu-Cys-Glu-Gln-His for the Mr 18,000 peptide and Gln-Ala-Asp-Glu-Asp-Tyr-Ser-His-Asp-Leu for the Mr 25,000 peptide. The N-terminal sequence of the Mr 18,000 peptide was identical to that of the kallikrein. Both peptides contained carbohydrate side chains as judged by staining with periodic acid-Schiff's base. The results indicate strongly that trypsin hydrolyses two specific bonds of human urinary prokallikrein selectively, which are cleaved upon physiological activation to yield the two-chain kallikrein.

Enzyme Activation↗
PubMed1986

Biosynthesis of porcine kidney D-amino acid oxidase.

The biosynthesis of a porcine kidney peroxisomal enzyme, D-amino acid oxidase (EC 1.4.3.3., DAO), was investigated. Pig kidney mRNA as well as free and membrane-bound polysomes were used to investigate in vitro protein synthesis using a rabbit reticulocyte lysate. mRNA and free polysomes, but not membrane-bound polysomes, directed the synthesis of DAO. To examine the in vivo synthesis of the enzyme, a pig kidney cell line (LLC-PK1) was biosynthetically labelled. Both the in vitro and in vivo synthesized DAO had the same molecular weight, 38,000, as that of the purified enzyme. These results indicate strongly that DAO is synthesized on free ribosomes and transferred to the interior of peroxisomes without any proteolytic modification.

Animals↗
PubMed1986

Local macular ERG in patients with Best's disease.

We examined a pair of siblings, a 10-year-old girl (case 1) and a 12-year-old girl (case 2), with Best's disease. The visual acuity was nearly normal in both patients. The central visual field measured with auto-plot tangent screen revealed a small relative paracentral scotoma only in the left eye of case 2. We failed to detect any abnormality in photopic and scotopic electroretinogram (ERG) recorded with Ganzfeld stimuli and the electrooculogram light rise was absent in both patients. Local macular ERG was recorded under a fundus monitor by infrared television fundus camera with test spots of 5, 10, and 15 degrees in diameter. The center of the stimulus spot was always on the fovea during the recording. The local macular ERG was absent in both patients. Our results of local macular ERG may indicate disturbance of the central portion of the retina.

Child↗
PubMed1986

Two cases of retinal degeneration with an unusual form of electroretinogram.

An unusual form of retinal degeneration is reported in 15-year-old girl and 11-year-old girl with different pedigrees, which resembles the cases reported by Gouras and associates (1983). The subjective symptoms in these patients included decreased visual acuity, photophobia, anomalous color vision and night blindness. Electroretinograms (ERGs) in these two patients were identical in substance and revealed drastic alterations in both photopic and scotopic functions. The stimulus versus intensity response curve in a single-flash ERG showed an unusual form. This peculiar supernormal response was elicited by bright stimuli although the stimulus threshold was extremely elevated.

Adolescent↗
PubMed1986

The pattern electroretinogram in patients with optic nerve disease.

We analyzed the electroretinogram elicited by pattern stimuli (PERG) in 29 patients with unilateral optic nerve disease. The normal fellow eyes served as a control. When the normal fellow eye was covered and the patient was asked to watch the center of the pattern stimuli with the affected eye, the poor fixation often caused irregular eye movements which resulted in a poor reproducibility of the response. In such instance we opened the normal fellow eye for fixation, which helped to stabilize the affected eye being examined even when visual acuity was extremely poor. The cross-talk phenomenon of the ERG and the reflection of the VER from the normal fellow eye were proved negligible in this recording condition. We analyzed PERGs in comparison with the visual acuity and the degree of optic atrophy. Unlike the results of many previous authors, little correlation was observed between PERG and these two factors. Most patient showed normal or only slightly abnormal PERG, even when the visual acuity was extremely poor and the optic disc was completely atrophic. Our results suggest that, at least with our method, PERG has extremely limited value in detection of optic nerve disease.

Adult↗
PubMed1986

Congenital stationary night blindness with negative electroretinogram. A new classification.

An analysis of 64 patients with congenital stationary night blindness showed that all had essentially normal fundi. Electroretinography (ERG) showed a normal a wave with extremely reduced b wave (negative type) when recorded with a single bright white stimulus in the dark. We classified these patients into two groups based on the evaluation of rod ERG and/or psychophysical dark adaptation measured with an 11 degree test target at 15 degrees in the upper part of the retina. One group (35 patients) lacked rod function (complete type). Nine patients could not be classified. No pedigree showed a complete and incomplete type in one family. Differences between the two groups in refractive error, photopic function, and oscillatory potentials in the ERG suggest a different pathogenesis. Our analysis may provide a new classification of congenital stationary night blindness with a negative ERG.

Adolescent↗
PubMed1986

A simplified method of treating retinal detachment with macular hole. Long-term follow-up.

Eighteen patients with macular hole retinal detachment and no visible posterior vitreoretinal connections were treated by one of two methods. In ten patients with extensive retinal detachment, the subretinal fluid was released in the temporal scleral side, and 1.0 mL or more of air or gas was injected into the vitreous cavity through the pars plana. In eight patients with localized retinal detachment in the posterior pole, 0.7 mL or more of gas was injected into the vitreous cavity after 0.3 to 0.5 mL of aqueous humor was released. Macular buckling, macular diathermy, or vitrectomy was not used. After the operation, the patients were placed in a prone position for at least six hours a day until the air or gas disappeared from the vitreous cavity. In 15 of 18 patients, the retina remained attached during follow-up periods that ranged from four to 32 months (average, 14 months). This operation is easy and safe and requires no sophisticated instruments. In addition, the macula is not damaged, as it can be by diathermy and buckling. This procedure should be the treatment of choice in patients with retinal detachments with macular holes but without other breaks or visible vitreous adhesion.

Aged↗
PubMed1986

Temporary use of intraocular silicone oil in the treatment of complicated retinal detachment.

Complicated retinal detachments in 99 eyes were successfully managed by intraocular injections of silicone oil with or without pars plana vitrectomy. The silicone was then subsequently removed after panretinal photocoagulation. Any remaining anterior vitreous cortex near the vitreous base and/or preretinal proliferative tissue causing traction of the retina was also removed by a vitrectome or extracted by a hooked needle after the silicone-fluid exchange had been performed. The preretinal proliferation occurred in some cases even after silicone oil had been removed. Recurrent detachments were discovered in 8 of the 99 eyes and were managed successfully by reinjections of the silicone. Other silicone reinjections were required in two eyes with diabetic retinopathy and two nondiabetic eyes because of frequent rebleeding into the vitreous cavity.

Eye↗
PubMed1986

Corneal permeability of aldose reductase inhibitor, M79175. I. In vitro study using corneal permeability apparatus.

Transcorneal permeability of M79175, aldose reductase inhibitor (Eisai), and various factors influencing it were examined using excised rabbit cornea mounted on the methacrylate apparatus. High permeability was exhibited and this was independent of the concentration of M79175. Cornea hydrated by exposure to the eye drop solution of high concentration of benzalkonium chloride, which had an enhancing effect on the permeability of M79175. Corneal hydration was also caused by the solution of low pH. These findings will show the basic conditions for this eye drop solution to be an artificial tear fluid.

Aldehyde Reductase↗