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Biomedical subjects

Y Kitazawa

Publications and source records attributed to Y Kitazawa.

At least 55 records · Page 3Linked to original sources
PubMed1999

Disc hemorrhage and peripapillary atrophy in apparently healthy subjects.

PURPOSE: We estimated the prevalence of disc hemorrhage and peripapillary atrophy in apparently healthy subjects. METHODS: We reviewed consecutive plain color fundus photographs of 12,140 eyes of 6,070 subjects (male/female=4,079/1,991) who visited a health consultation center. RESULTS: We analyzed 11,934 eyes of 5,967 subjects with good quality of photographs. Disc hemorrhage was found in 36 eyes of 35 subjects (0.6%). The prevalence of disc hemorrhage was significantly greater in women 60 years of age or older (Fisher's exact test, p=0.0004). The prevalence of peripapillary atrophy (zone Beta, zone Alpha), and suspected glaucomatous excavation in eyes with disc hemorrhage was 66.7%, 86.1% and 25.0%, respectively, and significantly greater than that (29.1%, 52.9% and 1.7%) in eyes without disc hemorrhage (Fisher's exact test, p<0.0001). CONCLUSIONS: Disc hemorrhage is more frequent in women over 60 years of age and is significantly associated with peripapillary atrophy in otherwise apparently healthy Japanese people.

Adult↗
PubMed1999

Biphasic intraocular pressure response to calcitonin gene-related peptide.

PURPOSE: To examine the effects of calcitonin gene-related peptide (CGRP) on intraocular pressure (IOP). METHODS: IOP was periodically measured in rabbits treated with intravitreal injection (20 ael) of either: 1) CGRP (10(-4) approximately 10(-7) M) into one eye; 2) CGRP (10(-4) or 10(-6) M) into both eyes 30 min after intravitreal administration of CGRP-(8-37) (10( -3) M), a CGRP1 receptor antagonist, into one eye; 3) CGRP (10(-4 ) or 10(-6) M) into one eye 30 min after intravenous administration (200 mg/kg) of either Nw-nitro-L-arginine methyl ester (L-NAME), a nonselective inhibitor of nitric oxide synthase (NOS), or aminoguanidine (AG), a selective inhibitor of inducible NOS; or 4) CGRP (10(-4) or 10(-6) M) into one eye along with intraperitoneal indomethacin (50 mg/ kg at -1 and 4 h). RESULTS: CGRP (10(-4) and 10(-5) M) produced a biphasic IOP response, which consisted of an early ocular hypertensive phase and a subsequent sustained hypotensive phase. While CGRP (10(-6) M) yielded only a profound IOP reduction. CGRP-(8-37) significantly inhibited the IOP elevation induced by CGRP (10(-4) M) and completely abolished the IOP reduction induced by CGRP (10(-6) M). The IOP increase induced by CGRP (10(-4) M) was completely abolished by L-NAME, but not affected by AG. The IOP reduction induced by CGRP (10(-6) M) was not affected by L-NAME. Indomethacin did not significantly affect the IOP responses to CGRP. CONCLUSIONS: CGRP dose-dependently produces a biphasic IOP response, which is mediated by CGRP1 receptors. It is suggested that constitutive NOS is involved in the early ocular hypertensive response.

Animals↗
PubMed1999

Analysis of myocilin mutations in 1703 glaucoma patients from five different populations.

A glaucoma locus, GLC1A, was identified previously on chromosome 1q. A gene within this locus (encoding the protein myocilin) subsequently was shown to harbor mutations in 2-4% of primary open angle glaucoma patients. A total of 1703 patients was screened from five different populations representing three racial groups. There were 1284 patients from primarily Caucasian populations in Iowa (727), Australia (390) and Canada (167). A group of 312 African American patients was from New York City and 107 Asian patients from Japan. Overall, 61 different myocilin sequence variations were identified. Of the 61 variations, 21 were judged to be probable disease-causing mutations. The number of probands found to harbor such mutations in each population was: Iowa 31/727 (4.3%), African Americans from New York City 8/312 (2.6%), Japan 3/107 (2.8%), Canada 5/167 (3.0%), Australia 11/390 (2.8%) and overall 58/1703 (3. 4%). Overall, 16 (76%) of 21 mutations were found in only one population. The most common mutation observed, Gln368Stop, was found in 27/1703 (1.6%) glaucoma probands and was found at least once in all groups except the Japanese. Studies of genetic markers flanking the myocilin gene suggest that most cases of the Gln368Stop mutations are descended from a common founder. Although the specific mutations found in each of the five populations were different, the overall frequency of myocilin mutations was similar ( approximately 2-4%) in all populations, suggesting that the increased rate of glaucoma in African Americans is not due to a higher prevalence of myocilin mutations.

Asian People↗
PubMed1999

[Clinical results and complications of refractive surgery].

PURPOSE: To evaluate the efficacy of photorefractive keratectomy (PRK) with a scanning type excimer laser MEL-60 (AESCLUP-MEDITEC, Co). SUBJECTS AND METHOD: We performed PRK on 102 eyes of 62 myopic patients whose refraction ranged from-3.00 to -12.50 D (mean, -6.47 D) and examined the clinical results of postoperative refraction and complications. RESULTS: At 12, 18, and 24 months after the operation, the mean refraction was -1.57 +/- 1.25D, -1.63 +/- 1.51 D and -1.73 +/- 1.47 D. At 12 months after the operation, 36 eyes (46.2%) were within +/- 0.5 D of intended correction, 61 eyes (78.3%) within +/- 1.0 D, and 76 eyes (97.4%) within +/- 2.0 D. Twenty-four months after the operation, 12 eyes (37.5%) were within +/- 0.5 D, 18 eyes (56.3%) within +/- 1.0 D and 29 eyes (90.6%) within +/- 2.0 D. The complications were as follows: keratitis filamentosa was observed in 10 eyes (10.5%), decrease of contrast sensitivity in 7 eyes (7.4%), subepithelial corneal haze in 4 eyes (1.2%), steroid-induced glaucoma was 2 eyes (2.1%), increase of astigmatism in 2 eyes (2.1%), decrease of best corrected visual acuity in 2 eyes (2.1%), and corneal ulcer in 1 eyes (1.1%). CONCLUSION: PRK with a scanning type excimer laser MEL-60 was effective to reduce refractive error in low and mild myopia, but there were some complications, so that a long, careful follow-up seems necessary.

Adult↗
PubMed1999

[Effect of mitomycin C dissolved in a reversible thermosetting gel on outcome of filtering surgery in the rabbit].

PURPOSE: Based on our previous report that showed enhanced transfer of mitomycin C to the sclera and the conjunctiva by dissolving the antiproliferative in a reversible thermo-setting gel, we conducted a study to investigate the efficacy of the mitomycin C-gel in the rabbit. METHODS: We subconjunctivally injected 0.1 ml of the mitomycin C-gel solution containing several amounts of the drug. Trephination was performed in the injected region 24 hours later. Intraocular pressure measurement, and photography and ultrasound biomicroscopic examination of the filtering bleb were done 1, 2, and 4 weeks postoperatively. RESULTS: The gel containing 3.0 micrograms or more mitomycin C significantly enhanced bleb formation in addition to reducing the intraocular pressure. CONCLUSION: The reversible thermo-setting gel seems to facilitate filtration following glaucoma filtering surgery in the rabbit and deserves further investigation as a new method of mitomycin C application.

Animals↗
PubMed1999

Optic nerve and peripapillary choroidal microvasculature of the rat eye.

PURPOSE: To investigate the three-dimensional microvascular anatomy of the optic nerve and peripapillary choroid in the rat eye. METHODS: Gross vascular anatomy of the posterior eye segment of Wistar rats was studied in serial microsections with a light microscope. The optic nerve and peripapillary choroidal vessels were sequentially microdissected, using methylmethacrylate corrosion microvascular castings, and were examined with a scanning electron microscope to determine the three-dimensional relationships of the vessels. RESULTS: The posterior ciliary artery traveled along the inferior side of the optic nerve sheath, directly entered the optic nerve head, and divided into three branches: the central retinal artery and medial and lateral long posterior ciliary arteries, which provided several short branches to the choroid. The optic nerve head vasculature was consistently nourished by a recurrent arteriole from the central retinal artery and an arteriole from the choroidal artery at the peripapillary choroid. The central retinal vein flowed into a venous anastomosis along the optic disc border of the peripapillary choroid. Capillaries within the optic nerve drained into the central retinal vein, the marginal venous anastomosis of the peripapillary choroid, and the pial veins, all of which flowed into the posterior ciliary veins along the optic nerve sheath. CONCLUSIONS: The findings illustrate vascular anatomic differences in optic nerve and peripapillary choroidal microcirculation between rat and human. In rats, the peripapillary choroid plays a significant role in both blood supply and venous drainage of the optic nerve head. The central retinal artery also contributes to the optic nerve head circulation.

Animals↗
PubMed1998

Cytogenetic clonality analysis in monosomy 7 associated with juvenile myelomonocytic leukemia: clonality in B and NK cells, but not in T cells.

It remains unclear which lymphoid lineages are involved in juvenile myelomonocytic leukemia (JMML). We report a JMML patient who acquired monosomy 7 after intensive chemotherapy. In this case, the expression of monosomy 7 was analyzed in T, B and natural killer (NK) cells highly purified from peripheral blood mononuclear cells of the patient. The fluorescence in situ hybridization method revealed the expression of monosomy 7 in B cells, but not T cells. Half of the NK cells expressed monosomy 7; when NK cells were divided into CD2- and CD2+ populations, this abnormality was positive in 91.1% of CD2- NK cells but in only 14.7% of CD2+ NK cells. These results suggest that, in this JMML patient who acquired monosomy 7 after intensive chemotherapy, B cells and half of NK cells, but not T cells, have monosomy 7.

B-Lymphocytes↗
PubMed1998

Vascular pathogenesis of normal-tension glaucoma: a possible pathogenetic factor, other than intraocular pressure, of glaucomatous optic neuropathy.

Elevated intraocular pressure is significant in the pathogenesis of glaucomatous optic neuropathy in glaucoma, however a number of studies suggest that pressure-independent factor(s) are also associated with the pathogenesis. In this article, the significance of vascular pathogenesis in glaucoma is discussed. A brief overview of substances used to treat glaucoma, independent of an effect on intraocular pressure, such as calcium channel blockers, is also discussed.

Animals↗
PubMed1998

Effects of nitric oxide synthase inhibitor on intraocular pressure and ocular inflammation following laser irradiation in rabbits.

PURPOSE: To examine the effects of nitric oxide synthase (NOS) inhibitors on intraocular pressure (IOP) and ocular inflammation following laser irradiation of the rabbit iris, and to investigate the involvement of nitric oxide (NO). METHODS: Thirty min after the intravenous administration of a nonselective inhibitor of NOS, N omega-nitro-L-arginine methyl ester (L-NAME, 1-100 mg/kg), or a selective inhibitor of iNOS, aminoguanidine (AG, 100 mg/kg), Q-switched Nd:YAG laser irradiation was applied to the iris of albino rabbits at an energy level of 48 mJ. IOP was measured prior to and for 24 h after irradiation. In separate groups of rabbits, aqueous humor was withdrawn 30 min after irradiation to determine protein and prostaglandin (PG) E2 concentrations. RESULTS: Intravenously administered L-NAME dose-dependently inhibited the acute increase in IOP, the peak of which was observed at 30 min, following laser irradiation. The IOP increase was completely abolished by 100 mg/kg of L-NAME. This dose of L-NAME significantly reduced the elevation of protein concentration in aqueous humor following irradiation; however, this dose failed to affect the increase in PGE2 concentration On the other hand, the inhibitory effects of AG (100 mg/kg) on the increase in IOP and aqueous protein following laser irradiation were not significant. CONCLUSIONS: Intravenous administration of L-NAME significantly inhibits the IOP rise and the increase in protein concentration in aqueous humor following laser irradiation, but AG does not, suggest the involvement of cNOS in these ocular responses to laser irradiation.

Animals↗
PubMed1998

An image analysis study of cataract development after trabeculectomy with mitomycin C.

We prospectively measured quantitative changes in the crystalline lens after trabeculectomy with mitomycin C. Twenty-four eyes in 24 trabeculectomy cases were consecutively enrolled in the study. The enrollment criteria consisted of: phakic eye, no history of intraocular surgeries and no corneal opacification. The transparency of the lens was measured and analyzed by EAS-1000 preoperatively, then 1 and 3 months postoperatively. Changes occurred primarily in the anterior part of the lens, especially in the anterior subcapsular region. The multivariate regression analysis demonstrated an association of cataract development with age, myopic refraction, difference in preoperative and postoperative IOP and systemic hypertension.

Adult↗
PubMed1998

[The effect of carbon dioxide on intraorbital hemodynamics in glaucoma determined by color Doppler imaging].

We developed a new system to safely supply carbon dioxide (CO2) to man to investigate the effect of the gas vasodilator on orbital blood flow in open angle glaucoma (OAG) patients. Using the system, we determined orbital hemodynamics in OAG by color Doppler imaging (CDI) at baseline conditions and during CO2 supplementation sufficient to increase end-tidal CO2% by 10%. Seven OAG patients (mean age, 60.9 +/- 16.4 years; normal-tension glaucoma/primary open-angle glaucoma = 5/2) were included in the study. CDI was performed to measure resistance index (RI), and peak-systolic and end-diastolic blood flow velocities (PSV & EDV) of the ophthalmic artery (OA) and the central retinal artery (CRA). Systemic conditions including oxygen saturation and blood pressure were monitored throughout the period of the CO2 inhalation. CO2 significantly increased PSV and EDV in the CRA (p = 0.0273, p = 0.0094, respectively; Wilcoxon signed-rank test), but not in the OA. Other parameters were not altered. The results suggest that CO2 inhalation increases blood flow velocities in distal arteries in OAG patients without affecting proximal vessels. The new system enables us to supply CO2 in a safe and controlled manner in glaucoma patients and to modify orbital hemodynamics.

Administration, Inhalation↗
PubMed1998

Incidence of elevation of intraocular pressure over time and associated factors in normal-tension glaucoma.

PURPOSE: The authors determine whether intraocular pressure (IOP) increases to levels that challenge the diagnosis of normal-tension glaucoma (NTG) and determine clinical factors associated with the IOP elevation. METHODS: Forty patients with NTG who met the following enrollment criteria were selected: IOPs less than 21 mm Hg during initial 24-hour pressure curve and throughout the subsequent 12 months; examined every 1 to 4 months for at least 4 years; and no ocular hypotensive treatment. The eye with the higher mean IOP during the initial 24-hour pressure curve was selected from each patient. The observation period ranged from 4.0 years to 7.8 years (mean, 5.2 years). Significant IOP elevation was defined as a significant increase (p < 0.05) of IOP over time, determined by Spearman rank correlation coefficient method. The IOP elevation was correlated to clinical factors by means of a logistic multiple regression analysis (LOGIST procedure using PC-SAS, SAS Institute, Inc. Cary, NC, U.S.A.). RESULTS: Eleven eyes were rated positive for IOP elevation. The regression model demonstrated that maximum IOP during the initial 24-hour pressure curve and the development of disc hemorrhage (DH) were significantly correlated with IOP elevation (p = 0.006 and p = 0.049, respectively). The odds ratios calculated were 1.98 per 1 mm Hg rise of maximum IOP during the initial 24-hour pressure curve and 6.54 for positive DH. CONCLUSIONS: Intraocular pressure might increase in NTG eyes following the initial diagnosis. A higher maximum IOP during initial 24-hour pressure curve and the development of DH during follow-up was significantly associated with subsequent IOP elevation in NTG patients.

Adult↗
PubMed1998

[An analysis of sclerodermatous graft-versus-host-disease after allogeneic bone marrow transplantation: CD8+CD57+T-cell proliferation and increased production of TGF-beta].

A 19-year-old woman with acute lymphoblastic leukemia received an allogeneic bone marrow transplantation (BMT) from an HLA-identical sibling during the second remission, on September 28, 1993. The conditioning regimen consisted of total body irradiation and cyclophosphamide. Short term methotrexate and cyclosporin A were given for prophylaxis of graft-versus-host disease (GVHD). On day 771 after BMT, she complained of bilateral forearm pain, and developed sclerotic lesions on the skin of the abdominal wall, forearms and legs. The diagnosis of sclerodermatous GVHD was established by skin biopsy on day 834. The values of CRP and IgG were elevated, and both antinuclear antibody and anti-DNA antibody became positive. Flow cytometric analysis showed a significant increase in the number of CD57+ cells after appearance of sclerotic change. In addition, 65% of CD8+ cells were positive for CD57. Circulating level of transforming growth factor (TGF)-beta 1 was high. These results suggest that overproduction of CD8+ CD57+ T cells and high level of circulating TGF-beta are related to the development of sclerodermatous GVHD.

Adult↗
PubMed1998

[Diagnostic capabilities of a classification program of the Heidelberg retina tomograph for early glaucomatous changes].

We investigated the diagnostic capabilities of a new glaucoma diagnostic softwave (classification program) of the Heidelberg retina tomograph for early glaucoma. Thirty eyes of 30 patients with early glaucoma (average visual field mean deviation = -3.7 dB) and 30 eyes of 30 normal subjects were enrolled. The criterion for early glaucomatous change was a visual field defect appearing earlier than Aulhorn classification stage II without considering the disc configuration. The diagnostic ability of three glaucoma specialists for the same eyes was evaluated using the Heidelberg retina tomograph analysis map. The agreement of two or three glaucoma specialists was accepted as the final judgment. Sensitivity, specificity, and diagnostic precision were calculated for all evaluations. The agreement between the classification program and glaucoma specialists was calculated with kappa statistics. Sensitivity, specificity, and diagnostic precision of the classification program were 80%, 83% and 82%, respectively. Those of the by glaucoma specialists were 83%, 90% and 87%, respectively. The agreement between the classification program and glaucoma specialists was excellent (kappa 0.73, % agreement 86.7%). The classification program will aid the diagnosis of early glaucomatous damage with high sensitivity and specificity.

Adult↗
PubMed1998

[Evaluation of the Swedish Interactive Thresholding Algorithm, a new thresholding algorithm, of the Humphrey field analyzer in normal subjects].

The Swedish Interactive Thresholding Algorithm (SITA) is a new thresholding algorithm that aims to obtain the same quality of visual fields in a shorter examination time than with the conventional up-and-down method. We investigated the correlation between thresholds measured with the SITA algorithm and those with the conventional up-and-down method in 47 eyes of 47 normal subjects. In each test point, thresholds with the SITA accurate and with the SITA fast showed significant correlation with those of the conventional method (r = 0.693, p < 0.0001 and r = 0.689, p < 0.0001, respectively). The mean deviation (MD) in the conventional method and the difference between MD values of the conventional method and SITA accurate and SITA fast were significantly correlated (r = -0.442, p < 0.006 and r = -0.509, p < 0.00092, respectively). The examination times of the SITA accurate and SITA fast were 48% and 27% of the conventional method. Although the new thresholding algorithm enables us to perform perimetric examination with relatively high accuracy, further investigations should be conducted before we apply it to glaucoma cases.

Algorithms↗
PubMed1998

A frequency-doubling perimetric study in normal-tension glaucoma with hemifield defect.

PURPOSE: The authors prospectively compare perimetric results obtained by conventional differential light sensitivity (DLS) perimetry and frequency-doubling perimetry (FDP) in normal-tension glaucoma (NTG) with a hemifield visual field defect, assuming that some of these eyes already have early glaucomatous changes in the "intact" hemifield. METHODS: Eleven eyes of 11 patients with NTG who met the enrollment criteria were studied. Seven eyes had an upper hemifield defect and four had a lower defect, determined by DLS with a Humphrey Field Analyzer (Zeiss-Humphrey, Inc., San Leandro, CA, U.S.A.). Frequency-doubling perimetry and DLS perimetry were conducted less than 7 days apart. To quantitatively detect nerve fiber layer defect (NFLD), scanning laser ophthalmoscopy was also performed. RESULTS: Of the 11 intact hemifields, seven showed NFLD. Of the seven, six also showed visual field defects by FDP. Of the four eyes without NFLD, two showed no defects in the intact hemifield by FDP. The threshold values of FDP and DLS perimetry did not significantly correlate in either the intact or the defective hemifields, or in the total field. The average test time of FDP was approximately 6 minutes. CONCLUSIONS: Frequency-doubling perimetry may detect early glaucomatous visual field defects.

Adult↗