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H Obazawa

Publications and source records attributed to H Obazawa.

At least 19 recordsLinked to original sources
PubMed2001

NADH-dependent dehydroascorbate reductase in the rabbit lens.

The present investigation demonstrates the existence of NADH-dependent dehydroascorbate (DHA) reductase activity in the soluble fraction of the rabbit lens. This DHA reductase was specific for NADH, and its apparent Km values for DHA and NADH were 5.7 mM and 4.0 microM, respectively. In a gel filtration of the lens soluble fraction on a Sephadex G-75 superfine column, the NADH-dependent DHA reductase activity was eluted at the oligomeric betaL1-crystallin fraction, which may also contain lambda-crystallin (a rabbit-specific crystallin). Furthermore, about 80% of protein fractions separated from the betaL1-crystallin fraction by DEAE-cellulose ion-exchange column chromatography exhibited DHA reductase activity. In the SDS-PAGE analysis of the protein fractions with DHA reductase activity, 32-33, 27 and 25 kDa protein subunits were commonly identified. These results suggest that oligomers of beta-crystallin and/or lambda-crystallin subunits may be associated with the DHA reductase activity. The present paper also discusses that the function of the reductase may be to enhance the antiphotoxidation capacity of the lens.

Animals↗
PubMed2000

Ascorbate Free Radical Reductase Activity in Vertebrate Lenses of Some Species.

Purpose: To clarify the function of ascorbate free radical (AFR) reductase in the lens antioxidation mechanism, we investigated the difference among species in AFR reductase activity in different vertebrate lenses.Materials and Methods: Soluble and insoluble fractions were prepared from the lenses of frogs, guinea pigs, rats, rabbits, pigs, and calves. AFR reductase and diaphorase activity of each fraction was determined.Results: AFR reductase activity in the lens soluble fraction was the highest in frogs. That of guinea pigs and rabbits was at the next level; there was only a little activity in rats and pigs, and none was detected in calves. Membrane-bound AFR reductase in the lens insoluble fraction was extracted by 0.3% Triton X-100. The membrane-bound enzyme activity was almost at the same level in frogs, rats, rabbits, and calves, and a little higher in guinea pigs and pigs. However, such species-specificity of AFR reductase activity as in the soluble fraction was not observed in 0.3% Triton X-100 extracts. Diaphorase activity was 3 to 9 times as much as AFR reductase activity in the soluble fractions of frogs, guinea pigs, and rabbits, but in 0.3% Triton X-100 extracts of all vertebrate species used, it was very high, 108 to 311 times the AFR reductase activity.Conclusion: These results suggest that the lens soluble and membrane-bound AFR reductases are individual enzyme molecules and have different anti-oxidative functions. The lenses of frogs, guinea pigs, and rabbits contain a near-ultraviolet (UV) light absorbing compound, reduced pyridine nucleotide at a high concentration. Therefore, the soluble AFR reductase activity may be high in the vertebrate lenses with a near-UV light filter, and enhance the antiphotoxidation of ascorbic acid.

Journal Article↗
PubMed2000

Rat lens epithelial cell damage and cataract formation induced by immunological response to bovine lens membrane protein

Purpose: To evaluate the correlation of cataractogenesis and immune mechanisms, we investigated the rat lens morphologically and immunologically.Methods and Results: Wistar rats were divided into three groups: Group A was immunized with bovine-lens membrane protein (B-LMP) and adjuvant, Group B was immunized with adjuvant only, and Group C was not given any treatment as a control. Titer levels of anti-B-LMP antibody and anti-rat-LMP antibody were elevated and posterior subcapsular cataract was developed in Group A. In flat preparations, a noncellular part in the lens epithelium was observed in all members of Group A. In this noncellular part, a lens capsule protruding into the lens epithelial cell layer was observed by light microscopy.Conclusion: These data suggest that lens epithelial cells may be damaged by immune response, causing the development of cataract.

Journal Article↗
PubMed2000

[Ascorbate free radical reductase activity in vertebrate lenses of some species].

PURPOSE: To clarify the function of ascorbate free radical (AFR) reductase in the lens antioxidation mechanism, we investigated the difference among species in AFR reductase activity in different vertebrate lenses. MATERIALS AND METHODS: Soluble and insoluble fractions were prepared from the lenses of frogs, guinea pigs, rats, rabbits, pigs, and calves. AFR reductase and diaphorase activity of each fraction was determined. RESULTS: AFR reductase activity in the lens soluble fraction was the highest in frogs. That of guinea pigs and rabbits was at the next level; there was only a little activity in rats and pigs, and none was detected in calves. Membrane-bound AFR reductase in the lens insoluble fraction was extracted by 0.3% Triton X-100. The membrane-bound enzyme activity was almost at the same level in frogs, rats, rabbits, and calves, and a little higher in guinea pigs and pigs. However, such species-specificity of AFR reductase activity as in the soluble fraction was not observed in 0.3% Triton X-100 extracts. Diaphorase activity was 3 to 9 times as much as AFR reductase activity in the soluble fractions of frogs, guinea pigs, and rabbits, but in 0.3% Triton X-100 extracts of all vertebrate species used, it was very high, 108 to 311 times the AFR reductase activity. CONCLUSION: These results suggest that the lens soluble and membrane-bound AFR reductases are individual enzyme molecules and have different antioxidative functions. The lenses of frogs, guinea pigs, and rabbits contain a near-ultraviolet (UV) light absorbing compound, reduced pyridine nucleotide at a high concentration. Therefore, the soluble AFR reductase activity may be high in the vertebrate lenses with a near-UV light filter, and enhance the antiphotoxidation of ascorbic acid.

Animals↗
PubMed1999

[Rat lens epithelial cell damage and cataract formation induced by immunological response to bovine lens membrane protein].

PURPOSE: To evaluate the correlation of cataractogenesis and immune mechanisms, we investigated the rat lens morphologically and immunologically. METHODS AND RESULTS: Wistar rats were divided into three groups: Group A was immunized with bovine-lens membrane protein (B-LMP) and adjuvant, Group B was immunized with adjuvant only, and Group C was not given any treatment as a control. Titer levels of anti-B-LMP antibody and anti-Rat-LMP antibody were elevated and posterior subcapsular cataract was developed in Group A. In flat preparations, a noncellular part in the lens epithelium was observed in all members of Group A. In this noncellular part, a lens capsule protruding into the lens epithelial cell layer was observed by light microscopy. CONCLUSION: These data suggest that lens epithelial cells may be damaged by immune response, causing the development of cataract.

Animals↗
PubMed1998

Collagen production by cultured human retinal pigment epithelial cells.

We investigated extracellular matrix produced by human retinal pigment epithelial cells (RPE) in vitro using electron microscopy and enzyme linked immunosorbent assay (ELISA). The thickness of the matrix under the cell layer was about 30 microns after 360 days of culture. It consisted mainly of fibrous and granular components. Type IV and V collagen were detected but type I and III were not detected by ELISA. It appeared that RPE can secrete type IV and V collagen and form a thick membrane which may cause proliferative vitreoretinopathy (PVR) by contraction. Control of RPE proliferation and secretion of extracellular matrix is indispensable for prevention of PVR.

Cells, Cultured↗
PubMed1997

[Detection of mycobacterial DNA with polymerase chain reaction in eye discharge and gastric juices in a case of scleritis].

We report a case of mycobacterial scleritis in which prompt diagnosis was made by the detection of mycobacterial DNA with polymerase chain reaction (PCR) in eye discharge and gastric juices, when conventional tests were negative. A 77-year-old woman who had a past history of pulmonary tuberculosis visited the outpatient clinic of Tokai University Hospital complaining of pain in her right eye. She was diagnosed as having scleritis and uveitis. There were no indications of active tuberculosis. We examined the gastric juices, sputum, and eye discharge by microscopy, culture, and PCR for detection of mycobacterium. The results of microscopy and culture were negative, but with PCR we detected atypical mycobacterium in eye discharge and gastric juices. After oral treatment with antituberculosis agents, the patient's eye symptoms disappeared. Detecting mycobacterial DNA with PCR could be useful for early diagnosis of mycobacterial scleritis, so that treatment with antituberculosis agents could be started.

Aged↗
PubMed1996

Ferricyanide reductase activity in cataractous human lens.

We assayed ferricyanide reductase activity (one of NADH-dependent diaphorase activities) in the soluble and insoluble fractions of cataractous human lenses. Activity of this reductase in both the soluble and insoluble fractions tended to decrease in order of cortex > nucleus periphery > nucleus center, and it was suggested that a decrease of the reductase activity is closely correlated with lens protein aggregation, and to some extent associated with the development of nuclear sclerosis (coloration) and cortical cataract. Furthermore, insoluble fraction had very high specific activity per mg insoluble protein in cortex, and the activity decreased sharply with an increase in the level of insoluble protein. The reductase activity in the insoluble fraction may be also related to the metabolic activity of plasma membranes.

Aged↗
PubMed1996

[Evaluation of risk factors of interferon-associated retinopathy in patients with type C chronic active hepatitis].

The risk factors of retinopathy associated with administration of interferon have not been fully clarified. We prospectively examined the retinal condition in 50 patients with type C chronic active hepatitis during alpha-interferon treatment. 43 patients (86%) were shown to have retinopathy during the course of interferon treatment, and were divided into three groups. Grades I, II and III were patients having a single episode of transient retinopathy with soft exudate or hemorrhage (34%), frequent episodes of retinopathy (42%), and exacerbating retinopathy requiring change or cessation of interferon treatment (10%), respectively. The patients with grade II and III were found to have the first retinal changes within 8 weeks after initiation of the interferon therapy. Early onset of retinopathy and presence of systemic disease such as diabetes mellitus or hypertension were risk factors for serious retinopathy with statistical significance. The grades of retinopathy were also well correlated with dosage and duration of interferon treatment. These results suggest that careful fundus examination is required up to 8 weeks after initiation of interferon treatment, especially for the patients with risk factors such as early onset of retinopathy, presence of systemic diseases, and large dosages and long duration of interferon therapy, in order to prevent serious ocular complications.

Adult↗
PubMed1995

Histochemical demonstration of acid phosphatase in a human retinal pigment epithelial cell line.

The retinal pigment epithelium (RPE) has numerous lysosomes and shows the highest acid phosphatase activity among eye tissues. In an established cell line of human RPE (K-1034), acid phosphatase activity, as a lysosome marker was investigated histochemically to evaluate the maintenance of original RPE characteristics. Even after 100 passages, RPE cells showed remarkable enzyme activity, and had numerous electron-dense bodies which were confirmed to be lysosomes. These results show that this cell line can maintain one of the vital functions of the RPE and provide useful experimental material for functional studies of the human RPE.

Acid Phosphatase↗
PubMed1995

Ascorbate free radical reductases and diaphorases in soluble fractions of the human lens.

Major and minor ascorbate free radical (AFR) reductases, with diaphorase activity, and three other diaphorases were separated from the human lens soluble fraction by DEAE-cellulose ion-exchange column chromatography. They were characterized for adsorptivity to ion-exchange and 5'AMP-Sepharose 4B affinity columns, kinetic properties, and substrate specificity. The latter diaphorases were closely correlated with NADH-cytochrome beta 5 reductase. The major and minor AFR reductases were regarded as a major diaphorase group different from two ubiquitous diaphorases, i.e., NADH-cytochrome beta 5 reductase and DT-diaphorase. A major AFR reductase was partially purified approximately 50 fold over the lens soluble fraction by ion-exchange, affinity, and gel filtration (Sephacryl S-200 HR) column chromatography. From the partially purified enzyme, 2 bands, one sharp and one diffuse, were obtained by native polyacrylamide gel electrophoresis. Two proteins, of 20 and 24 kDa, were identified in the active enzyme bands by SDS-polyacrylamide gel electrophoresis. This suggests that the 20 and/or 24 kDa proteins may be components of the major AFR reductase.

Chromatography, Affinity↗
PubMed1994

Soluble ascorbate free radical reductase in the human lens.

A major and a minor ascorbate free radical (AFR) reductase were separated from the soluble fraction in the human lens cortex by DEAE-cellulose ion-exchange column chromatography. These AFR reductases also exhibited diaphorase activity using dichlorophenolindophenol and ferricyanide as electron acceptors. The major AFR reductase was partially purified by 5'AMP-Sepharose 4B affinity column chromatography. This partially purified AFR reductase showed a single band of diaphorase activity in native polyacrylamide disc gel electrophoresis. This activity band corresponded to the major protein observed in protein staining by Coomassie Brilliant Blue. However, the protein staining by Coomassie Brilliant Blue showed this activity band surrounded by diffused staining. Molecular weight of the partially purified AFR reductase was determined to be 32 kDa by gel filtration, and the apparent Km value for AFR was about 15 microM. This major lens AFR reductase could be distinguished from soluble Neurospora, Euglena and cucumber AFR reductases, and from two ubiquitous enzymes with reduction activity of AFR and/or foreign compounds, ie, NADH-cytochrome b5 reductase and DT-diaphorase, by their molecular weights, Km values and/or ion-exchange chromatographic behaviors.

Adult↗
PubMed1994

Morphologic and chromosomal study of a human retinal pigment epithelial cell line.

A spontaneously established cell line of human retinal pigment epithelium (RPE) was investigated morphologically and studied by chromosomal analysis. Even after the 100th passage, cultured cells maintained epithelioid morphology, and had numerous microvilli and membrane-bound small dense bodies which looked like lysosomes. Abundant rough-surfaced endoplasmic reticulum and mitochondria were observed in the cytoplasm, suggesting that these cells were metabolically active. The absence of pigmentation was noted from the 6th passage. In chromosomal analysis, a small number of 2nd passage cells showed karyotypic changes. At the 12th passage, a single cell line (44, 6-monosomy and Y-missing) was established. By the 100th passage, further karyotypic changes were noted (low tetraploid). The 6-monosomy might have played an important role in the establishment of this cell line. These results indicated that this cell line underwent some changes in chromosomal count and pigmentation but retained many original morphological characteristics. After further evaluation of its characteristics, this cell line, K-1034, could be useful experimental material in the study of the function of the human RPE.

Adult↗
PubMed1993

Case-control study of senile cataract in Japan: a preliminary report.

A hospital-based case-control study of senile cataract was conducted in Japan from 1988 to 1990. Two hundred and twelve patients with senile cataract and 212 control subjects with the same age-sex distribution were interviewed and given an ophthalmological examination. Both groups were randomly selected outpatients from 9 hospitals. Associations between senile cataract and four groups of variables, factors regarded as risks, life style habits, general aging indices or other factors were analyzed, and the data was subjected to statistical analysis. An increased risk of cataract was found in males who were presently spending 7 hours or more outside daily (Odds ratio = 5.07) and in females with 4 or fewer remaining teeth (Odds ratio = 2.03). The findings from this study suggest that there may be a sex-related host sensitivity or life style which is predisposing to the development of senile cataract.

Adult↗
PubMed1993

[An epidemiological study of allergic conjunctivitis].

An epidemiological study focusing on the home environment and lifestyle was conducted in order to analyze the differences between a group of patients with allergic conjunctivitis only and a group with other allergic diseases associated with allergic conjunctivitis. Subjects were five hundred and sixty-four patients who visited the Ophthalmologic Clinic of Tokai University Hospital during 1990, and for controls 200 households were randomly selected from an elementary school list in Yokohama city. RAST score was measured in 102 patients. A mailed questionnaire was sent to 240 patients chosen at random and to 200 controls. Sixty patients and 139 controls responded to the questionnaire. RAST score showed no statistical difference between patients with allergic conjunctivitis only and patients with other allergic diseases associated with allergic conjunctivitis. Analysis of associations between RAST score and seasonal symptoms, showed very strong positive reactions to pollens in patients with seasonal symptoms. On the other hand, in patients with constant symptoms during the year, reaction was very strong to house dust and mite. Epidemiological factors causally associated with allergic conjunctivitis were compared among the controls, patients with allergic conjunctivitis only (Group I), patients with other allergic diseases (Group II) and all patients (Group III). Compared to controls, Groups II and III had significantly higher prevalence of past history of skin itching and inflammatory symptoms (p < 0.05 and p < 0.01, respectively). Group II subjects showed more frequent use of carpets, when compared to the controls (p < 0.05). The use of Japanese mattress (futon) was more frequent in Group II and III than controls (p < 0.05 for both comparisons).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Reduced glutathione levels in senile cataractous lens epithelial cells.

A sensitive assay, utilizing high performance liquid chromatography and sulfhydryl (SH) fluorescence labeling, was used for the quantitative determination of reduced glutathione (GSH) and cysteine (CySH) in senile cataractous lens epithelial cells. The capsule-epithelia (CE), obtained following cataract surgery, were soaked in 0.3 ml saline at room temperature for 1 hour. Detached epithelial cells and the capsule with attached residual cells were assayed for GSH and CySH. Regression analysis of the relation between epithelial protein content and capsule wet weight was performed to evaluate the amount of contamination of the CE samples with lens cortex. GSH levels in the cataractous lens epithelial cells were 23.0 +/- 11.2 (Mean +/- S.D.) nmol/mg protein (n = 15); CySH levels were 0.51 +/- 0.50 nmol/mg protein (n = 12). No differences in GSH levels were observed between immature and mature cataracts. Thus, GSH levels in the lens epithelial cells did not appear to decrease with the progression of the senile cataracts.

Aged↗