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Biomedical subjects

Y Miyake

Publications and source records attributed to Y Miyake.

At least 181 records · Page 10Linked to original sources
PubMed1998

Electroretinographic alterations during vitrectomy in human eyes.

BACKGROUND: We previously reported a new system of electroretinographic monitoring of the retinal function during vitrectomy in human eyes, and found that lowering the intravitreal temperature by applying an infusion solution kept at room temperature (used routinely for vitrectomy throughout the world) can alter the electroretinogram (ERG). This time we attempted to study the effect upon the ERG of replacing the intraocular medium and acutely elevating the intraocular pressure during vitrectomy. METHODS: Using a special contact lens with a built-in light-emitting diode light source, 30-Hz flicker ERG was quickly recorded under aseptic conditions. RESULTS: Acute, reversible reduction in amplitude was observed upon replacing the intraocular medium with air or silicon oil and during periods of acutely elevated intraocular pressure. Infusions of gentamicin or miconazole did not affect the ERG when intravitreal temperature and intraocular pressure were constant. CONCLUSION: The ERG monitor can reveal changes of the retinal function during vitrectomy, particularly when the infusion temperature, intraocular medium and intraocular pressure are kept constant.

Antifungal Agents↗
PubMed1998

Protective effects of lemon flavonoids on oxidative stress in diabetic rats.

The effects of lemon flavonoids, as crude flavonoids prepared from lemon juice, were investigated in diabetic rats. The oxidative stress of eriocitrin (eriodictyol 7-O-beta-rutinoside) and hesperidin (hesperetin 7-O-beta-rutinoside) on streptozotocin-induced diabetic rats was investigated. Diabetic rats were given a diet which contained 0.2% crude flavonoids, 0.2% eriocitrin, and 0.2% hesperidin. After the 28-d feeding period, the concentration of the thiobarbituric acid-reactive substance in the serum, liver, and kidney of diabetic rats administered crude flavonoids, eriocitrin, and hesperidin significantly decreased as compared with that of the diabetic group. The levels of 8-hydroxydeoxyguanosine, which is exchanged from deoxyguanosine owing to oxidative stress, in the urine of diabetic rats administered eriocitrin and hesperidin significantly decreased as compared with that of the diabetic rat group. Crude flavonoids, eriocitrin, and hesperidin suppressed the oxidative stress in the diabetic rats. These results demonstrated that dietary lemon flavonoids of eriocitrin and hesperidin play a role as antioxidant in vivo.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1998

Focal macular electroretinograms before and after successful macular hole surgery.

PURPOSE: To report changes in focal macular electroretinograms before and after successful macular hole surgery and to discuss whether preoperative retinal function can predict postoperative visual acuity. METHODS: In this prospective study, 28 consecutive eyes of 28 patients underwent vitrectomy for stage 2 or 3 full-thickness idiopathic macular hole. Focal macular electroretinograms using a 4-degree stimulus spot were obtained in 24 eyes of 28 patients, and those using a 5-degree stimulus spot were obtained in 24 eyes of 28 patients, to evaluate preoperative and postoperative amplitude and implicit time of the b-wave. Visual acuity was measured preoperatively and postoperatively, and results were translated into logMAR (minimum angle of resolution) values. RESULTS: After successful macular hole closure, the b-wave amplitude increased in 23 of 24 eyes measured with the 4-degree stimulus spot and in 19 of 24 eyes measured with the 5-degree stimulus spot. Postoperative b-wave amplitude recorded with either stimulus spot correlated with postoperative corrected visual acuity. The b-wave implicit time decreased in 15 of 20 eyes measured with the 4-degree spot and in 13 of 23 eyes measured with the 5-degree spot. Preoperative b-wave implicit time measured with the 5-degree stimulus spot correlated significantly (P = .001) with postoperative corrected visual acuity. CONCLUSIONS: Qualitative change (implicit time) is more important than quantitative change (amplitude) in electroretinograms for predicting postoperative corrected visual acuity. The function of the retinal tissue surrounding the hole may affect visual outcome.

Adult↗
PubMed1998

Regional cerebral blood flow during rewarming of cardiopulmonary bypass correlates with posthypothermic regional glucose use.

BACKGROUND AND OBJECTIVES: Although global measurements of cerebral blood flow and metabolism during and after profoundly hypothermic cardiopulmonary bypass have been performed both in experimental animals and in human beings, little is known about their regional changes. The purpose of this study was to investigate the changes in regional cerebral blood flow during profoundly hypothermic cardiopulmonary bypass and regional cerebral glucose use after cardiopulmonary bypass. METHODS: We measured regional cerebral blood flow with positron emission tomography during both the cooling (n=5) and rewarming (n=5) of hypothermic cardiopulmonary bypass in anesthetized dogs by continuously infusing 15O-labeled water. We altered the core temperature between 20 degrees and 37 degrees C. To assess the integrity of brain metabolism, we measured the regional cerebral glucose use by bolus injections of 18F-labeled 2-fluoro-2-deoxy-D-glucose. RESULTS: Regional cerebral blood flow decreased homogeneously during cooling. The regional cerebral blood flow at 20 degrees C was about one fourth of that at 37 degrees C. In contrast, at 24 degrees, 28 degrees , and 32 degrees C during rewarming, there were significant interregional differences in the regional cerebral blood flow for given temperatures (p=0.0075, 0.034, and 0.048, respectively). These interregional differences disappeared after rewarming. Although the regional cerebral blood flow significantly correlated with the regional cerebral glucose use in the control condition at 37 degrees C without cardiopulmonary bypass (r=0.75; p=0.00012), this correlation disappeared after profoundly hypothermic cardiopulmonary bypass (r=0.204; p=0.388). Regional cerebral blood flow at 32 degrees C during rewarming positively correlated with the regional cerebral glucose use after cardiopulmonary bypass (r=0.655; p=0.0017). CONCLUSION: The altered regional cerebral blood flow during rewarming of profoundly hypothermic cardiopulmonary bypass might affect regional brain metabolism.

Animals↗
PubMed1998

The augmentation of pituitary adenylate cyclase-activating polypeptide (PACAP) in streptozotocin-induced diabetic rats.

Pituitary adenylate cyclase activating polypeptide (PACAP), which was isolated from ovine hypothalamic extract, has been shown to have a physiological role in the regulation of insulin or islet functions. In streptozotocin (STZ)-induced diabetic rats, we examined the content of PACAP immunoreactivity and gene expression of three specific receptors. Four weeks after administration of STZ (50 mg/kg), plasma glucose levels increased 3.3-fold, and plasma insulin levels decreased to one-tenth as compared with the control. The content of PACAP immunoreactivity in the pancreas potently increased by 30%, but the content of vasoactive intestinal polypeptide (VIP) immunoreactivity was not changed. In the other tissues, the content of PACAP immunoreactivity did not significantly change except in the hypothalamus, which showed a 10% increment. In the expression level of PACAP/VIP receptors, semi-quantitative RT-PCR analysis revealed that VIP1/PACAP receptor mRNA significantly increased as compared with the other two types of receptors in the pancreas of STZ-induced diabetic rats. These findings suggest that PACAP and VIP1/PACAP receptor might be involved in the pathophysiology of diabetes mellitus.

Animals↗
PubMed1998

Development of step-specific PET tracers for studying fatty acid beta-oxidation: biodistribution of [1-(11)C] octanoate analogs in rats and a cat.

To evaluate the potential of [1-(11)C]-3-(R,S)-methyloctanoate (BMOA), [1-(11)C]-2-octynoate, and [1-(11)C]-2-decynoate as PET tracers for studying particular steps in fatty acid beta-oxidation, we examined the pharmacokinetics of these compounds in rats and a cat. In rats given these compounds, high levels of radioactivity accumulated in the heart, liver, and kidneys, suggesting their potential as tracers for studying beta-oxidation in these tissues. These organs were clearly visible with PET in a cat given BMOA, indicating the utility of BMOA for imaging these organs.

Animals↗
PubMed1998

Analysis of blood pressure responses during exercise by logistic function curve in hypertension: effects of age, gender and physical training.

During exercise blood pressure fluctuates from minute to minute and does not rise linearly with time. Blood pressure responses were evaluated during exercise by a logistic function curve. Thirty-nine hypertensive patients underwent exercise testing with an ergometer, employing a multistage method (25 watts increment, every 3 min). We plotted the exercise duration on the X-coordinate and systolic blood pressure on the Y-coordinate and blood pressure was assumed to form a logistic curve for exercise duration. The relationship of systolic blood pressure vs. exercise duration was better fitted into a logistic function curve than a linear regression model. The logistic curve was defined by lower plateau, upper plateau, SPX (the X-coordinate at the shift point) and df (SPX), the maximal slope at the shift point. The effects of aging, gender and physical training were then analyzed on the curve. Aging did not affect lower plateau, upper plateau and SPX but augmented df (SPX), indicating greater blood pressure responses in older subjects during exercise. In females the curve was shifted to the left compared to males (SPX: 4.9 vs. 8.3 min, P < 0.05) without changes in plateaux and df (SPX), indicating greater blood pressure responses than males. Physical training for 3 weeks decreased the lower plateau from 157 to 144 mmHg (P < 0.05) and shifted the curve to the right (SPX: 7.1 vs. 8.6 min, P < 0.05), indicating unchanged blood pressure responses after training because of the opposite effects by decreases in the lower plateau vs. the curve shift to the right. In conclusion, blood pressure during exercise is better delineated by a logistic function curve than a linear regression model. The biological or physiological significance of df (SPX) is not clear at present and needs further investigations.

Adult↗
PubMed1998

In vitro adherence of Streptococcus constellatus to dense hydroxyapatite and titanium.

Bacterial adherence to dense hydroxyapatite (HA) and titanium (Ti) rods was examined in vitro using Streptococcus constellatus ATCC27832. Streptoccus constellatus is associated with dental abscess and was isolated from the peri-implantitis. The dense HA was etched with 5% hydrofluoric acid for 0, 10, 20, 30, 40, and 50 s Adherence to the untreated dense HA was twice as high as the adherence to the Ti. The adherence to saliva-treated Ti was 13% higher than that to untreated Ti. The adherence was increased by acid-treatment of the dense HA, following a sigmoid curve from 20 to 50 s of treatment time. The dense HA has the capacity to receive more bacterial adherence than Ti and furthermore, the etched dense HA becomes more adherent.

Abscess↗
PubMed1998

Evidence for genetic heterogeneity in X-linked congenital stationary night blindness.

X-linked congenital stationary night blindness (CSNB) is a nonprogressive retinal disorder characterized by disturbed or absent night vision; its clinical features may also include myopia, nystagmus, and impaired visual acuity. X-linked CSNB is clinically heterogeneous, and it may also be genetically heterogeneous. We have studied 32 families with X-linked CSNB, including 11 families with the complete form of CSNB and 21 families with the incomplete form of CSNB, to identify genetic-recombination events that would refine the location of the disease genes. Critical recombination events in the set of families with complete CSNB have localized a disease gene to the region between DXS556 and DXS8083, in Xp11.4-p11.3. Critical recombination events in the set of families with incomplete CSNB have localized a disease gene to the region between DXS722 and DXS8023, in Xp11.23. Further analysis of the incomplete-CSNB families, by means of disease-associated-haplotype construction, identified 17 families, of apparent Mennonite ancestry, that share portions of an ancestral chromosome. Results of this analysis refined the location of the gene for incomplete CSNB to the region between DXS722 and DXS255, a distance of 1.2 Mb. Genetic and clinical analyses of this set of 32 families with X-linked CSNB, together with the family studies reported in the literature, strongly suggest that two loci, one for complete (CSNB1) and one for incomplete (CSNB2) X-linked CSNB, can account for all reported mapping information.

Female↗
PubMed1998

Prevalence of GBV-C/HGV infection in pregnant Japanese women.

Recently, a novel viral agent, hepatitis G virus, was identified by independent researchers from the serum of patients with liver disease, and termed GBV-C or HGV. At present, GBV-C and HGV are considered to be separate isolates of the same virus; however, the role of this virus in acute and chronic liver disease remains uncertain. Although vertical transmission is known to be one of the routes of transmission, the prevalence of GBV-C/HGV viremia in pregnant Japanese women is unknown. Thus, we determined this prevalence using the reverse transcription polymerase chain reaction (RT-PCR).

Female↗
PubMed1998

Fosfomycin reduces CD15s-related antigen expression of Streptococcus pyogenes.

We have previously shown the immunological mimicry of human sialyl-Lewis(x) (CD15s) by a surface antigen of Streptococcus pyogenes. This mimicking surface antigen may act as a ligand to the selectin family and may induce antibody production against CD15s on host cells, suggesting a possible role in the pathogenesis of S. pyogenes. In this study, the effects of antibiotics on the CD15s-related antigen expression of S. pyogenes were examined at a concentration below the MIC (sub-MIC). The amounts of CD15s on the surfaces of S. pyogenes cells and on the surfaces of S. pyogenes biofilms were determined by a whole-cell enzyme-linked immunosorbent assay and by laser scanning fluorescence microscopy, respectively, by using an anti-CD15s monoclonal antibody. At the sub-MICs, fosfomycin (1R,2S-1,2-epoxypropyl phosphonic acid), its enantiomer (1S,2R-1,2-epoxypropyl phosphonic acid), and benzylpenicillin significantly inhibited the CD15s expression of all strains studied. The effects of fosfomycin and its enantiomer on biofilms were also observed by scanning electron microscopy. Incubation of S. pyogenes with the sub-MIC of fosfomycin or its enantiomer, which has no antibacterial activity, reduced the amount of CD15s on the biofilm surface and made it smooth. These results suggest that fosfomycin or its enantiomer might be useful for preventing S. pyogenes adherence to human CD15s receptors and the resulting immunological pathogenicity.

Anti-Bacterial Agents↗
PubMed1998

Extrafoveal photostress recovery test in glaucoma and idiopathic central serous chorioretinopathy.

BACKGROUND/AIMS: A photostress recovery test was designed to differentiate macular diseases from optic nerve disorders, but recently an abnormal recovery time was reported in glaucoma. The purpose of this study was to search for the difference in abnormality of the photostress recovery test between glaucoma and idiopathic central serous chorioretinopathy (ICSC). METHODS: This study involved 21 normal subjects, 14 patients, with ICSC and 10 patients with primary open angle glaucoma (POAG). A scanning laser ophthalmoscope (SLO) was used with microperimetry for bleaching the test point and measuring the recovery of sensitivity. Photostress recovery time (SLO-PSRT) could be measured at extrafoveal points outside and inside the affected area. The initial sensitivity change and the time constant of recovery after bleaching were calculated by fitting an exponential equation to the data. RESULTS: In normal subjects, neither the initial sensitivity change nor the time constant were correlated with the location of the test point. In 14 patients with ICSC, the initial sensitivity change in the detached area was significantly smaller than that in the unaffected area which was not significantly different from that in the age matched normal subjects. The time constant in the detached area was significantly longer than that in the unaffected area, which was not significantly different from that in the normal subjects. In 10 patients with POAG, the initial sensitivity change inside and outside the scotoma was not significantly different from that of age matched normal subjects. The time constant inside the scotoma was significantly longer than that outside the scotoma, which was not significantly different from that of the age matched normal subjects. CONCLUSION: Both ICSC and POAG showed a prolonged time constant of recovery, but the initial sensitivity change was reduced only in ICSC. The difference in our results between ICSC and POAG may be caused by the difference of the retinal pathology. Further, the SLO-PSRT is very useful when the lesion is located outside the fovea.

Adult↗
PubMed1998

[Reverse mutation test of disodium mercaptoundecahydro-closo-dodecaborate with bacteria].

Disodium mercaptoundecahydro-closo-dodecaborate (BSH) was studied for mutgenic potential by reverse mutation test with bacteria. The test was carried out using five different tester strains, S. typhimurium TA100, TA1535, TA98 and TA1537, and E. coli WP2uvrA by the preincubation method. BSH was tested at concentrations ranging from 156 to 5000 micrograms per plate. The test substance did not induce revertants dose-dependently in any strains with or without a metabolic activation system. Therefore, it was concluded that BSH was not mutagenic in the present reverse mutation test.

Borohydrides↗
PubMed1998

Double infection with Giardia lamblia and Salmonella paratyphi A associated with acute renal failure.

While traveling in India, a previously healthy twenty-year-old man had febrile diarrhea. The patient was prescribed medical therapy, and all symptoms were resolved. Fourteen days later, however, similar symptoms recurred. The patient was admitted to a local hospital, but was transferred to our department because of oliguria. Salmonella paratyphi A was isolated from blood and stool specimens, and Giardia lamblia was identified in his stool. The patient's condition was complicated by acute renal failure. The patient received tosufloxacin and metronidazole. Renal function recovered completely without hemodialysis. Paratyphoid fever and giardiasis were resolved. It is suggested that giardiasis exacerbated the paratyphoid fever.

Acute Kidney Injury↗
PubMed1998

Recording multifocal electroretinogram on and off responses in humans.

PURPOSE: To record the on and off responses of the multifocal photopic electroretinogram (ERG) from the human retina and to explore how each ERG component (a-, b-, and d-waves) changes at different retinal eccentricities. METHODS: Multifocal ERGs were recorded with the visual evoked response imaging system. Sixty-one densely packed stimulus elements were square wave-modulated between stimulus on and stimulus off, according to a binary m-sequence at a rate of 4.7 Hz under a constant background illumination. The ERGs were recorded with a bipolar Burian-Allen bipolar contact lens electrode from five normal subjects. Response densities (amplitude per retinal area) were calculated for five different eccentric rings. RESULTS: The response densities for all components (a-, b-, and d-waves) decreased with increasing retinal eccentricities. The ratio of the d-wave to b-wave amplitudes was minimal in the central retina and increased toward the periphery. The ratio of a-wave to b-wave amplitudes also increased toward the peripheral retina. CONCLUSIONS: These results demonstrate that the on and off responses of the human cone ERGs have different spatial distributions across the human retina, and they suggest a change in the photopic retinal circuitry with increasing retinal eccentricities.

Adult↗
PubMed1998

[Coenzyme Q10].

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Coenzymes↗
PubMed1998

[Imaging of myocardial perfusion and metabolism with positron emission tomography].

Positron emission tomography (PET) has been providing new information in the diagnosis and the pathophysiological assessment of heart diseases. The PET tracers commonly used in Japan are 13N-ammonia, 18F-fluorodeoxyglucose (FDG) for imaging of myocardial perfusion and metabolism, respectively. Measurement of regional myocardial blood flow by 13N-ammonia dynamic PET scan and a compartment model analysis is applied to the functional estimation of coronary stenotic lesions and the detection of perfusion abnormalities in hypertrophic heart diseases, familial hyperchlesterolemia and other diseases with possible microvascular lesions. 18F-FDG is commonly used to differentiate ischemic but viable tissue from myocardial scar in coronary artery disease and also used to detect cardiac tumor and the cardiac involvement in sarcoidosis. In addition to these two tracers, 11C-acetate is now expected to provide the clinical analysis of pathophysiology of heart failure by estimating the efficiency of energy conversion of the heart into external work.

Acetates↗