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Biomedical subjects

Akira Sawada

Publications and source records attributed to Akira Sawada.

16 recordsLinked to original sources
PubMed2006

Improvement of scotopic electroretinograms and night blindness with recovery of serum zinc levels.

BACKGROUND: We sought to determine the cause of reduced scotopic and photopic electroretinograms (ERGs) and night blindness in a 46-year-old man with liver dysfunction but no history of alcoholism. CASE: A 46-year-old Japanese man with a complaint of visual difficulties in dim light for 1 month. OBSERVATIONS: By electrophysiological investigation, the patient was found to have low levels of serum zinc and vitamin A on admission. The rod b wave was unrecordable, and the bright-flash ERGs were reduced, with the a wave > b wave. The amplitudes of the cone and 30-Hz flicker responses were also reduced, and their implicit times were prolonged. Three weeks after admission, the patient's serum zinc level recovered to normal levels, but his serum vitamin A level was still low. The symptoms of night blindness were gone, and the rod ERGs and single bright-flash responses were within normal limits. However, the cone ERGs and 30-Hz flicker responses were still depressed. CONCLUSIONS: The recovery of scotopic function together with the recovery of zinc but not vitamin A levels suggests that the ERG changes were most likely related to low zinc levels.

Cholagogues and Choleretics↗
PubMed2006

A new calcium channel antagonist, lomerizine, alleviates secondary retinal ganglion cell death after optic nerve injury in the rat.

PURPOSE: We investigated whether lomerizine, a new diphenylmethylpiperazine calcium channel blocker, exerted a neuroprotective effect on axonal or retinal damage induced by optic nerve injury in the rat. METHODS: A partial crush lesion was inflicted unilaterally on the optic nerve, 2 mm behind the globe, in adult Wistar albino rats. Animals were treated with the vehicle, 10 or 30 mg/kg lomerizine. Each solution was given orally twice daily for 4 weeks. One week before euthanization, Fluoro-Gold (FG) was injected into both superior colliculi to retrogradely label surviving retinal ganglion cells (RGCs). Approximately 1 month after the optic nerve injury, the retinal damage was assessed morphologically, and the optic nerve axons surrounding the initial lesion were examined histologically. RESULTS: The mean RGC density in the control group decreased to 65.9 +/- 1.32% of the contralateral eye, whereas the systemic application of 10 or 30 mg/kg of lomerizine significantly enhanced the RGC survival to 88.1 +/- 0.38% and 89.8 +/- 0.28%, respectively. Histological examination of damaged axons revealed no significant enhancement of the density or total number of axons of the retinal ganglion cells in the lomerizine-treated group. The crush force we employed caused no significant morphological differences in the retinal layers between the sham-operated animals and the animals from the experimental groups. CONCLUSIONS: Our findings suggest that lomerizine alleviates secondary degeneration of RGCs induced by an optic nerve crush injury in the rat, presumably by improving the impaired axoplasmic flow.

Animals↗
PubMed2006

Incidence of disc hemorrhages in open-angle glaucoma before and after trabeculectomy.

PURPOSE: To investigate the effects of reduction of intraocular pressure (IOP) by surgical intervention on the frequency of disc hemorrhages in eyes with primary open-angle glaucoma (POAG) and normal-tension glaucoma (NTG). DESIGN: Retrospective study. METHODS: We studied 99 eyes of 99 patients with POAG and 50 eyes of 50 patients with NTG, who underwent trabeculectomy with adjunctive mitomycin C (MMC) and were followed regularly at 1 to 3-month intervals at the Glaucoma Service of Gifu University Hospital. We applied Kaplan-Meier life-table analysis for the detection of disc hemorrhages before and after trabeculectomy. RESULTS: Trabeculectomy significantly reduced IOP (in POAG: 19.6 +/- 4.4 down to 11.1 +/- 4.2 mm Hg; in NTG: 15.3 +/- 1.5 down to 11.3 +/- 4.5 mm Hg; mean +/- SD). Life-table analysis revealed that the final cumulative probability of detecting a disc hemorrhage after surgery in POAG was 5.5 +/- 2.2% (calculated probability +/- SE) and was significantly lower than that (33.4 +/- 7.8%) before surgery (P < 0.0001, log-rank test). Likewise, the final probability after surgery in NTG was 23.1 +/- 6.3% and was significantly lower than that (42.1 +/- 8.8%) before surgery (P = 0.0063, log-rank test). CONCLUSIONS: IOP reduction via surgical intervention significantly decreases the frequency of disc hemorrhages in open-angle glaucoma patients.

Adult↗
PubMed2005

Patient positioning method based on binary image correlation between two edge images for proton-beam radiation therapy.

A new technique based on normalized binary image correlation between two edge images has been proposed for positioning proton-beam radiotherapy patients. A Canny edge detector was used to extract two edge images from a reference x-ray image and a test x-ray image of a patient before positioning. While translating and rotating the edged test image, the absolute value of the normalized binary image correlation between the two edge images is iteratively maximized. Each time before rotation, dilation is applied to the edged test image to avoid a steep reduction of the image correlation. To evaluate robustness of the proposed method, a simulation has been carried out using 240 simulated edged head front-view images extracted from a reference image by varying parameters of the Canny algorithm with a given range of rotation angles and translation amounts in x and y directions. It was shown that resulting registration errors have an accuracy of one pixel in x and y directions and zero degrees in rotation, even when the number of edge pixels significantly differs between the edged reference image and the edged simulation image. Subsequently, positioning experiments using several sets of head, lung, and hip data have been performed. We have observed that the differences of translation and rotation between manual positioning and the proposed method were within one pixel in translation and one degree in rotation. From the results of the validation study, it can be concluded that a significant reduction in workload for the physicians and technicians can be achieved with this method.

Algorithms↗
PubMed2004

Removal of Cr(VI) from contaminated soil by electrokinetic remediation.

A new process for the removal of hexavalent chromium [Cr(VI)] contaminated soil is described. The process provides for an efficient removal of anionic chemicals from contaminated soils. Chromate anions were removed from the soil to the anodic reservoir by the moving force of electromigration. In this process, the chromate anions that accumulate in the anodic reservoir are simultaneously eliminated by using a column packed adsorbent. The adsorbent (immobilized tannin) used was chemically incorporated into cellulose. Cr(VI) was found to be adsorbed to this adsorbent efficiently. In the electrokinetic process, the pH of the aqueous solution in the anodic reservoir was decreased by the electrolysis of water. In the present study, the pH of the solution in the anodic reservoir is maintained at pH 6 by the addition of an aqueous alkaline solution during the electrokinetic process. The advantage of pH control is that it promotes the release of Cr(VI) from the soil by electromigration, thus permitting the maximum adsorption of Cr(VI) on the immobilized tannin. Simultaneous collection of Cr(VI) from the anodic reservoir leads to the protection from secondary contamination with Cr(VI).

Adsorption↗
PubMed2004

Optic disc hemorrhages detected in a large-scale eye disease screening project.

PURPOSE: To investigate the prevalence and characteristics of optic disc hemorrhages. MATERIALS AND METHODS: We took IMAGEnet fundus photographs of 14,779 participants, aged 40 years or older in a large-scale eye disease screening project conducted in Tajimi, Japan. A single researcher reviewed all of the photographs for the presence of ocular abnormality in the optic nerve head and retina, paying special attention to the presence or absence of optic disc hemorrhages. Glaucomatous optic neuropathy was diagnosed based on the presence of nerve fiber layer defects and/or the appearance of the optic disc. RESULTS: Fundus photographs of 13,965 cases (27,930 eyes) were successfully reviewed bilaterally. We found disc hemorrhages at 92 locations of 92 (0.3%) eyes of 88 (0.6%) cases. Twenty-four hemorrhages of 23 (26%) cases were found in bilateral non-glaucoma cases and the remaining 68 hemorrhages of 65 (74%) cases were found in glaucoma cases. The prevalence of disc hemorrhages was 8.2% in 793 glaucoma cases and 0.2% in non-glaucoma cases. Hemorrhages developed significantly more frequently in females and in the elderly. The hemorrhages were predominantly found in the inferotemporal and superotemporal regions. The intraocular pressure was less than 20 mm Hg in all cases. The mean intraocular pressure was 15.0 mm Hg for glaucoma cases with hemorrhages and 13.9 mm Hg for non-glaucoma cases with hemorrhages. CONCLUSION: Disc hemorrhages occur more frequently in females, in elderly persons, and in glaucoma cases in Japanese aged 40 or older. The intraocular pressure of the eyes with disc hemorrhages is close to that of the normal population.

Adult↗
PubMed2004

A technique for noninvasive respiratory gated radiation treatment system based on a real time 3D ultrasound image correlation: a phantom study.

This paper proposes a new respiratory gated radiation treatment system that allows real-time tumor localization while avoiding invasive operation to a patient. The proposed system employs a three-dimensional (3D) ultrasound device, a 3D digital localizer, and a real-time image processing system. At the planning time, CT and 3D ultrasound reference data are simultaneously acquired under a breath-hold condition. At the treatment time, ultrasound data on three orthogonal planes are acquired and transferred to the image processing system on a real-time basis. Subsequently, normalized image correlation indices using the reference and the real-time ultrasound data are calculated for the three orthogonal planes after performing real-time coordinate transform using the 3D digital localizer attached to an ultrasound probe. Prior to the system execution, the coordinate transform matrices are partially calculated using an ultrasound calibration phantom and the 3D digital localizer. A trigger pulse to a linac can be generated when the normalized image correlation index exceeds a predetermined threshold level. Experiments have been carried out using a moving-target phantom that simulates a patient respiratory motion. We have observed that the variation of the calculated real-time correlation index synchronizes with the periodical motion of the moving-target, suggesting that real-time localization for a moving tumor is feasible with the proposed system.

Algorithms↗
PubMed2004

A novel neuroprotectant against retinal ganglion cell damage in a glaucoma model and an optic nerve crush model in the rat.

PURPOSE: To investigate the effects of repeated treatments with a neuroprotective compound, R(-)-1-(benzo [b] thiophen-5-yl)-2-[2-(N, N-diethylamino) ethoxy] ethanol hydrochloride (T-588), on retinal ganglion cell (RGC) survival in rat eyes with elevated intraocular pressure (IOP) or after optic nerve crush. METHODS: An increase in IOP was induced by a single laser treatment to the trabecular meshwork in one eye of adult Wistar rats. Crush injury was unilaterally produced by clipping the optic nerve 2 mm behind the globe. RGC density was estimated by counting fluorescent dye-labeled cells in the flatmount of the retina. The optic nerve damage in the crush model was also evaluated histologically. RESULTS: In the elevated IOP model, RGC survival decreased to 72.9% +/- 3.8% (mean +/- SEM) of that of the contralateral control eye on the eighth day after laser irradiation. Repeated treatments with T-588 at 30 mg/kg twice daily significantly enhanced RGC survival (86.0% +/- 2.2%, P = 0.0242) without the reduction of IOP. In the optic nerve crush model, RGC survival diminished to 37.2% +/- 8.4% of that of the contralateral control eye after 4 weeks. Repeated applications with T-588 at 10 mg/kg twice daily significantly enhanced RGC survival (77.8% +/- 2.1%, P = 0.0038). Histologically, the rat optic nerve in the group treated with T-588 at 10 mg/kg retained a near-normal morphology. CONCLUSIONS: T-588 has a neuroprotective effect against RGC death caused by elevated IOP and optic nerve crush in the rat.

Animals↗
PubMed2004

Preparation of artificially spiked soil with polycyclic aromatic hydrocarbons for soil pollution analysis.

To confirm the method for preparing artificially spiked soil with polycyclic aromatic hydrocarbons (PAHs), we tested the homogeneity of PAHs in spiked soils, which were prepared by three different procedures, by using kaolin and ando soil. When the slurry of kaolin and acetone containing PAHs were evaporated by a rotary evaporator at 30 - 35 degrees C, the most homogeneous distribution of PAHs was obtained in the spiked soil. This procedure was applied to the preparation of PAH-spiked soil for natural soil (ando soil). Such spiked soils can be useful as the standard materials for standardization of the analytical methods for PAHs in the soil and sediment samples.

Polycyclic Compounds↗
PubMed2003

Influence of humic substances on the removal of pentachlorophenol by a biomimetic catalytic system with a water-soluble iron(III)-porphyrin complex.

To investigate some basic aspects of soil remediation using biomimetic catalysts, the effects of humic substances (HSs) on the removal of xenobiotics, such as pentachlorophenol (PCP), were investigated. The use of a biomimetic catalytic system using tetra(p-sulfophenyl)porphine-iron(III) (Fe(III)-TPPS) and potassium monopersulfate (KHSO5) resulted in the disappearance of PCP, accompanied by dechlorination. In addition, this process was enhanced by the presence of several types of HSs. The degrees of enhancement (% delta(PCP)60) achieved by the presence of HSs from peat and compost soils were larger than those in the presence of other types of HSs (tropical peat, brown forest, and ando soils). In control experiments, no PCP disappearance and dechlorination were observed in the presence of only KHSO5, only Fe(III)-TPPS, or combinations of HSs and either KHSO5 or Fe(III)-TPPS. To better understand the role of added HS in enhancing or inhibiting PCP disappearance, correlations between the chemical parameters of the HSs and % delta(PCP)60 were investigated. The most effective HSs had lower carboxylic acid contents and lower degrees of unsaturation. The carboxylic acid content and degree of unsaturation increase with the extent of humification. Therefore, HSs of a lower degree of humification would be predicted to be more useful in enhancing the disappearance of PCP in an Fe(III)-TPPS/KHSO5 system.

Catalysis↗
PubMed2003

Electrokinetic remediation of clayey soils containing copper(II)-oxinate using humic acid as a surfactant.

The utility of humic acid (HA) as a surfactant for use in the electrokinetic remediation (ER) of the clayey soils containing copper(II)-oxinate (Cu(OX)(2)) was examined. A small simulator of ER was devised, which consisted of three types of artificial soils on the basis of the commercial kaolin: kaolin, kaolin + HA and kaolin + Cu(OX)(2). The layers of kaolin containing HA and Cu(OX)(2) were sandwiched between two kaolin layers. In all experiments, a constant dc voltage gradient of 2.2V/cm was applied through the soil for 30h, and the pH of the solution in the anodic chamber was maintained at 7.0. Generally, HA has a negative charge at a neutral pH. However, the HA was mainly transferred to the cathodic chamber. This shows that the driving force of the HA in the system used herein is predominantly due to electroosmotic flow. Moreover, the amount of Cu(OX)(2) removed from the clayey soils in the presence of HA was three times larger than those in the absence of HA. This can be attributed to the fact that the water solubility of Cu(OX)(2) is enhanced by the presence of HA. Thus, we conclude that HA has a potential for use as an amendment for the ER of hydrophobic chemicals, such as Cu(OX)(2).

Aluminum Silicates↗
PubMed2003

Effects of humic substances on the pattern of oxidation products of pentachlorophenol induced by a biomimetic catalytic system using tetra(p-sulfophenyl)porphineiron(III) and KHSO5.

In the presence of humic substances (HSs), the oxidative conversion of pentachlorophenol (PCP) was found to be efficiently catalyzed by tetra(p-sulfophenyl)porphineiron(III) (Fe(III)-TPPS) using KHSO5 as an oxygen donor. Ortho-tetrachloroquinone (o-TeCQ), 2-hydroxyl-nonachlorodiphenyl ether (2H-NCDE), 4-hydroxyl-nonachlorodiphenyl ether (4H-NCDE), and octachlorodibenzo-p-dioxin (OCDD) were identified as the major byproducts of the reaction. Decreased amounts of these byproducts were produced in the presence of HS. In particular, the addition of HSs with a lower degree of humification resulted in a large decrease in the formation of dimers, such as 2H-NCDE, 4H-NCDE, and OCDD. More than 60% of the chlorine, which was released from PCP, was found in the HS fractions after the reaction. This suggests that chlorinated intermediates from PCP were incorporated into the HS. Pyrolysis-GC/MS and 13C NMR studies confirmed that the binding of the chlorinated intermediates was covalent in nature and that the intermediates were copolymerized with HS via oxidative coupling reactions. A Microtox test demonstrated that the toxicity of the HS fraction containing PCP-derived intermediates was much lower than that of the mixture of PCP and HS in the absence of a catalytic reaction.

Catalysis↗
PubMedDate not supplied

Correlation between individual differences in intraocular pressure reduction and outflow facility due to latanoprost in normal-tension glaucoma patients.

PURPOSE: The amount of intraocular pressure (IOP) reduction achieved by the use of latanoprost eyedrops varies among patients, and there are even nonresponders. This report examines whether there is any correlation between the amount of individual variability in IOP reduction and the uveoscleral outflow facility after latanoprost eyedrop instillation in normal-tension glaucoma patients. METHODS: Sixteen normal-tension glaucoma patients (mean age, 56.4 years) were enrolled in the study to investigate the relationship between the amount of IOP reduction and outflow facility. Before treatment, subjects underwent circadian IOP measurement and then tonography, and the outflow facility was calculated. Subsequently, patients began treatment once daily with latanoprost instillation in one eye. After 4 weeks of daily latanoprost treatment, circadian IOP was measured again. RESULTS: Mean pretreatment outflow facility was 0.23 +/- 0.05 microl/min per mmHg. On average, latanoprost instillation decreased IOP by 2.8 mmHg, but the reduction varied among individuals from -0.3 mmHg to 5.8 mmHg. No significant correlation was noted between the outflow facility and the IOP decline associated with latanoprost. CONCLUSION: Because there was no significant correlation between individual IOP reduction by latanoprost and outflow facility, the differences in substantial change in uveoscleral outflow after latanoprost administration may be one explanation for the individual variation in IOP reduction after treatment with this drug.

Adult↗
PubMedDate not supplied

Diurnal variation of intraocular pressure in suspected normal-tension glaucoma.

PURPOSE: To assess diurnal variations of intraocular pressure (IOP) in suspected normal-tension glaucoma (NTG) patients with subsequent long-term observation to detect changes that may lead to a new diagnosis. METHODS: Diurnal variation of IOP was measured in a sitting position at 2-h intervals for 24 h in a total of 569 subjects with suspected NTG. RESULTS: Thirty of the 569 subjects (5.3%) showed IOP values exceeding 20 mmHg during the 24-h monitoring and were diagnosed as having primary open-angle glaucoma (POAG). In subjects in whom NTG was definitely diagnosed based on the results of the 24-h monitoring, the average maximum, minimum, and mean IOP was 16.1, 11.7, and 13.9 mmHg, respectively, and the mean diurnal variation in IOP was 4.4 mmHg. The peak time was observed outside clinic hours (1800-0800) in 41.4% of patients, and the trough time was observed during clinic hours (1000-1600) in 15.9%. In 2.9% of NTG subjects, the diagnosis was eventually changed to POAG during follow-up. CONCLUSION: Assessment of diurnal variations of IOP in suspected NTG patients is useful for the differential diagnosis of POAG from NTG and for establishment of a baseline, which may affect the management plan.

Adolescent↗
PubMedDate not supplied

Neuroprotective effects of R(-)-1-(benzo[b]thiophen-5-yl)-2- [2-(N,N-diethylamino)ethoxy]ethanol hydrochloride (T-588) against retinal ganglion cell death induced by elevated intraocular pressure in rat.

PURPOSE: We investigated whether T-588 can attenuate retinal ganglion cell (RGC) death induced by elevated intraocular pressure (IOP). METHODS: IOP elevation was induced unilaterally by argon laser irradiation of the rat trabecular meshwork 4 days after an intracameral injection of India ink. We orally administered either the vehicle, or 10, 30, or 100 mg/kg body weight (BW) of T-588 24 hours before the laser application. Five days after the laser application, 1.5 microL of 3% Fast Blue was injected into the superior colliculi bilaterally. Three days after the Fast Blue injection, the eye was enucleated and the retinal whole flatmount was prepared. Labeled ganglion cells were counted by fluorescence microscope with an ultraviolet filter. RESULTS: Laser treatment significantly increased the IOP. The percentages of labeled RGCs in the lasered eyes as compared with the nonlasered contralateral eyes were 78.0 +/- 11.6% in the control group, 78.7 +/- 12.9% in the 10 mg/kg BW group, 79.1 +/- 13.0% in the 30 mg/kg BW group, and 91.0 +/- 9.0% in the 100 mg/kg BW T-588-treated group. The survival rate of RGCs was significantly higher in the 100 mg/kg BW T-588-treated group than in the control group. CONCLUSION: T-588 appears to have a neuroprotective effect on retinal ganglion cells in this ocular hypertensive model.

Administration, Oral↗