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Biomedical subjects

Shigeo Tsukahara

Publications and source records attributed to Shigeo Tsukahara.

At least 19 recordsLinked to original sources

The OPA1 gene polymorphism is associated with normal tension and high tension glaucoma.

PURPOSE: To assess whether genetic polymorphisms of optic atrophy 1 (OPA1) are associated with primary open-angle glaucoma (POAG). DESIGN: Prospective case control association study. METHODS: Japanese patients with normal tension glaucoma (NTG, n = 194), and high tension glaucoma (HTG, n = 191), and 185 control subjects were analyzed for the OPA1 intervening sequence (IVS) 8+4 cystosine thymine (C/T) and IVS 8+32 thymine cystosine (T/C) polymorphisms using pyrosequencing technique. RESULTS: There was a significant difference in the OPA1 IVS 8 +32 T/C genotype frequencies between the NTG patients and control subjects (P = .0074), and the frequency of the cystosine (C) allele was significantly higher in the NTG patients compared with the control subjects (19.3% vs 11.6%, P = .0036). Adjusted for age, gender, refractive error, and intraocular pressure, an almost two-fold increased risk of NTG (P = .004, odds ratio 2.27, 95% confidence interval 1.30 to 3.97) was found with the OPA1 IVS 8 +32 C allele. Although there was no significant difference in the OPA1 IVS 8 +32 T/C genotype frequencies between the HTG patients and control subjects (P = .24), the age at the time of diagnosis (53 +/- 11.0 years, median value +/- median absolute deviation) in the HTG patients with the OPA1 IVS 8 +32 C allele was significantly younger than that (57 +/- 12.0 years) in the HTG patients without C allele (P = .048). CONCLUSIONS: The OPA1 IVS 8 +32 T/C polymorphism is associated with NTG, and may be used as a marker for this disease association. This polymorphism also influences the phenotypic feature in patients with HTG and should be considered to be a genetic risk factor not only for NTG, but also for HTG.

Aged↗

Methylenetetrahydrofolate reductase gene polymorphisms c.677C/T and c.1298A/C are not associated with open angle glaucoma.

PURPOSE: To assess whether or not the c.677C/T and c.1298A/C genetic polymorphisms of the methylenetetrahydrofolate reductase (MTHFR) gene are associated with open angle glaucoma (OAG). METHODS: Genomic DNA was examined in a cohort of 131 Japanese patients with normal tension glaucoma (NTG), 133 patients with primary open angle glaucoma (POAG), and 106 control subjects. The mean age at the time of blood sampling was 62.8+/-13.3 years (mean+/-SD) in the patients with NTG, 61.8+/-15.4 years in the patients with POAG, and 65.0+/-10.5 years in the control subjects. MTHFR c.677C/T and c.1298A/C genotype and allele frequencies were determined using pyrosequencing analysis, and the findings were compared between the OAG patients and control subjects. The frequencies of compound MTHFR c.677C/T and c.1298A/C genotypes were also compared between OAG patients and control subjects. RESULTS: No significant differences were observed (p>0.05, chi2 test or Fisher's exact test) regarding the MTHFR c.677C/T genotype (TT: 14.5%, CT: 44.3%, CC: 41.2% for patients with NTG; TT: 20.3%, CT: 41.4%, CC: 38.3% for patients with POAG; TT: 17.9%, CT: 36.8%, CC: 45.3% for control subjects) and c.1298A/C (CC: 0%, AC: 38.9%, AA: 61.1% for patients with NTG; CC: 2.3%, AC: 32.3%, AA: 65.4% for patients with POAG; CC: 0.9%, AC: 41.5%, AA: 57.6% for control subjects). There were no allele frequencies between the NTG or POAG patients and the control subjects. In addition, no significant differences (p>0.05, chi2 test) were found in the frequencies of the compound MTHFR c.677C/T and c.1298A/C genotypes between the NTG or POAG patients and the control subjects. CONCLUSIONS: The MTHFR c.677C/T and c.1298A/C polymorphisms were not found to be associated with NTG and POAG. Further studies in the different ethnic populations should be performed to elucidate the relationship between MTHFR and OAG.

Adenine↗

Effects of small-incision phacoemulsification and intraocular lens implantation on anterior chamber depth and intraocular pressure.

PURPOSE: To examine prospectively the effects of small-incision phacoemulsification and intraocular lens implantation (PEA+IOL) on anterior chamber depth (ACD) and intraocular pressure (IOP) using a newly developed scanning peripheral ACD analyzer (SPAC). MATERIALS AND METHODS: Twenty-eight eyes of 21 patients who underwent PEA+IOL without any complications were examined and divided into 7 eyes each of grades 1 to 4 according to the Van Herick technique. The SPAC measured ACD consecutively from the vicinity of the pupil center to the periphery at 0.4-mm intervals. Changes in ACD and IOP as a result of PEA+IOL were investigated, and the factors contributing to the changes in ACD and IOP were examined. RESULTS: PEA+IOL increased ACD significantly at all groups. The average changing rates were 3.19 +/- 0.67 times (Van Herick grade 1), 2.00 +/- 0.80 times (Van Herick grade 2), 1.92 +/- 0.32 times (Van Herick grade 3), and 1.36 +/- 0.65 times (Van Herick grade 4), respectively. The closer to the pupil center the measurement point was, the larger was the increase in ACD. However, the rates of increase in ACD were similar among the measurement points. The increases in ACD were significantly large in patients having a shallow preoperative ACD and a small optic axis length. The IOP reduction became significantly large in eyes with a shallow preoperative ACD. CONCLUSIONS: The SPAC enabled quantitative measurement of changes in ACD from the vicinity of the pupil center to the periphery as a result of PEA+IOL. Changes in ACD resulting from PEA+IOL were thought to exert a greater effect on aqueous humor outflow facility as the postoperative ACD became shallower.

Aged↗

Comparison between newly developed scanning peripheral anterior chamber depth analyzer and conventional methods of evaluating anterior chamber configuration.

PURPOSE: To compare the newly developed scanning peripheral anterior chamber depth analyzer (SPAC) with the Van Herick technique, the Shaffer grading system, and ultrasound biomicroscopy (UBM), in terms of accuracy of measurement of peripheral anterior chamber depth (ACD). METHODS: The subjects were well-controlled glaucoma patients who were being treated at the University of Yamanashi Hospital. Ten eyes from each of the 4 groups classified as Shaffer grades 1 to 4 were evaluated by SPAC, the Van Herick technique, and UBM. All measurements were performed independently on the temporal side in a masked fashion. SPAC evaluated ACD consecutively from the pupil center to the limbus at 0.4 mm intervals. UBM measurements were carried out at a depth of 500 mum (angle-opening distance 500) from the scleral spur. A dummy eye was used for evaluating SPAC measurement accuracy. RESULTS: The results of SPAC measurement were well correlated with those of the Van Herick technique and the Shaffer grading system. The SPAC measurement results were also significantly correlated with angle-opening distance 500. The correlation coefficients at distances of 2, 4, 4.8, and 5.6 mm from the pupil center were r=0.68, 0.69, 0.69, and 0.61, respectively, and the P values of all the correlations were less than 0.0001. Study of the dummy eye revealed that SPAC has high accuracy for measuring ACD and that the coefficient variances were less than 1.0% at all measured points. CONCLUSIONS: The results of SPAC measurement correlate well with those of the conventional methods.

Aged↗

Development of a fully automated peripheral anterior chamber depth analyzer and evaluation of its accuracy.

PURPOSE: The aim of this study was to improve the scanning peripheral anterior chamber depth analyzer (SPAC) for measuring anterior chamber depth (ACD), differentiating eyes with shallow anterior chamber, and automatically categorizing eyes into subgroups based on the ACD values. We also investigated its accuracy for measuring anterior ocular biometry. MATERIALS AND METHODS: The improved SPAC system was equipped with an auto-focusing system for measuring ACD from the optical axis to the limbus without contacting the ocular surface, in addition to an auto-measuring system for determining central corneal thickness (CCT) and corneal radius of curvature (CRC). This system was also equipped with an auto-diagnosing program for differentiating eyes with narrow angle and an auto-classifying program for categorizing eyes into 12 subgroups according to the ACD values. A dummy eye was used for investigating the measurement accuracy and reproducibility of CCT, CRC, and ACD. Measurement duration and clinical availability were investigated using healthy subjects and glaucoma patients. RESULTS: The SPAC-measured CCT, CRC, and ACD values were very similar to the theoretical values obtained from the dummy eye and their coefficients of variation were less than 1%. This system completed ACD measurement in 15.6+/-1.0 seconds and the mean coefficient of variation of ACD was 8.8+/-2.3%. The improved SPAC system successfully differentiated eyes with narrow angle from those with wide open angle. CONCLUSIONS: The improved SPAC system can measure ACD easily with good accuracy and reproducibility, and is considered to be suitable for evaluating ACD in routine examinations and screening eyes with narrow angle.

Adult↗

Different expression role among glutamate transporters in rat retinal glial cells under various culture conditions.

Using cultured rat retinal glial cells, the changes in the expression of glutamate transporters (GLTs) under such conditions as the degree of confluence of the cells, hypoxia, glutamate loading, and potassium loading, were assessed. After the retinal glial cells were isolated from 3-day-old Sprague-Dawley rats, GLAST, GLT-1, and EAAC1 mRNA expression was confirmed by reverse transcription-polymerase chain reaction (RT-PCR) and their protein expression was confirmed by Western blot analysis and immunostaining. Changes in the expression of the GLTs at 6 h after passage and at confluence, during culture in 5% oxygen, during glutamate loading and during potassium loading were assessed using real-time PCR. Although the GLAST mRNA expression was increased during glutamate and potassium loading, no changes in the expression were observed during hypoxia and at confluence. By contrast, the GLT-1 mRNA expression was increased during hypoxia and at confluence, but not during glutamate and potassium loading, and the EAAC1 mRNA expression was not changed only during glutamate loading. The expression of EAAC1 in the cultured retinal glial cells was confirmed. The expression of the GLTs varied according to the environment and the type of load suggests that the involvement of the GLTs in retinal physiology and pathology varies depending on the subtype.

Animals↗

The apolipoprotein E gene polymorphism is associated with open angle glaucoma in the Japanese population.

PURPOSE: To assess whether genetic polymorphisms of the apolipoprotein E (APOE) gene are associated with open angle glaucoma (OAG) in the Japanese population. METHODS: Genomic DNA was examined in a cohort of 310 Japanese patients with OAG and 179 control subjects. The average age was 63.5+/-14.4 years (mean+/-SD) for the OAG patients and 65.5+/-11.6 years for the control subjects. The presence or absence of OAG in patients and controls was based on clinical examination and/or ophthalmic records. The APOE allele frequency (epsilon2, epsilon3, and epsilon4 alleles) was studied by restriction fragment length polymorphism, and compared between OAG patients and control subjects. The association between the intraocular pressure (IOP) and the APOE alleles was also evaluated. RESULTS: There was a significant difference in the APOE genotype frequencies between these groups (p=0.0006 chi2 test). The frequencies of the epsilon2 and epsilon4 alleles were significantly lower in the OAG patients (epsilon2: 2.6%; epsilon4: 6.0%) compared to the control subjects (epsilon2: 5.0%, p=0.048; epsilon4: 10.6%, p=0.012; Fisher's exact test). The frequency of the epsilon3 allele was significantly higher in the OAG patients (91.4%) compared to the control subjects (84.4%, p=0.0010; Fisher's exact test). Adjusted for age, gender, and IOP, an appropriate three fold reduction in OAG risk (odds ratio [OR] 0.29, 95% confidence interval [CI] 0.10 to 0.80; p=0.018) was found with the epsilon2 allele and a two fold increased risk of OAG (OR 1.97, 95% CI 1.06 to 3.67; p=0.033) was found with the epsilon3 allele. The maximum IOP (18.3+/-6.0 mm Hg) in patients with the epsilon4 allele was significantly lower than that (21.3+/-9.1 mm Hg) in patients without the epsilon4 allele (p=0.006, Student's t-test). CONCLUSIONS: The APOE gene polymorphism is associated with OAG in the Japanese population. Further studies in the other ethnic populations should be performed to elucidate the relationship between APOE and OAG.

Aged↗

Mutations in the optineurin gene in Japanese patients with primary open-angle glaucoma and normal tension glaucoma.

The optineurin gene (OPTN) was identified as a gene that causes primary open-angle glaucoma (POAG) and normal tension glaucoma (NTG). To investigate the frequency of sequence changes in OPTN in Japanese glaucoma patients, single-strand conformation polymorphism analysis and subsequent sequence analysis were performed for genotyping OPTN in 165 unrelated Japanese patients with POAG and 148 patients with NTG, with 196 control subjects without glaucoma as reference subjects. Out of four mutations reported to be associated with risk and to cause disease in Caucasian patients, sequence alterations in 458G > A and 691_692insAG were not detected in any investigated Japanese patients with glaucoma, and alterations in 1944G > A and 603T > A, were present in similar frequencies in glaucoma patients and control subjects. The current results suggest that there may be certain racial differences between Japanese and Caucasians with respect to OPTN genotypes.

Adult↗

Association of magnetic resonance imaging of anterior optic pathway with glaucomatous visual field damage and optic disc cupping.

PURPOSE: To investigate the association of magnetic resonance imaging (MRI) of anterior optic pathway with glaucomatous visual field damage and optic disc cupping. SUBJECTS AND METHODS: Twenty-three healthy volunteers (controls) and 31 glaucoma patients (14 with primary open angle glaucoma and 17 with normal tension glaucoma) were enrolled. All the participants showed no abnormal signs in their intracranial space and optic tract causing optic nerve atrophy and visual field defect, as confirmed by MRI. Multislice T1-weighted spin-echo imaging was performed in the sagittal plane followed by the coronal plane. MRI enabled the evaluation of the diameter of the optic nerve located in the retro-bulb space and the height of the optic chiasm in an observer-masked fashion. The MRI data were compared with the mean deviation (MD) score of the full threshold static visual field test and the optic cup-disc ratio (C/D ratio). RESULTS: The optic nerve diameter was significantly smaller in glaucoma patients (2.25 +/- 0.33 mm) than in controls (2.47 +/- 0.24 mm) and the height of the optic chiasm was significantly shorter in glaucoma patients (2.12 +/- 0.37 mm) than in controls (2.77 +/- 0.36 mm). The optic nerve diameter showed significant correlation with MD score (r = 0.547, P = 0.001) and C/D ratio (r = 0.407, P = 0.009). These correlations are similar to that between MD score and C/D ratio (r = 0.490, P = 0.001). The height of the optic chiasm showed significant correlation with MD score (r = 0.503, P = 0.01) and low correlation with C/D ratio (r = 0.339, P = 0.113). CONCLUSION: Glaucoma affects the anterior visual pathway anterogradely at least up to the optic chiasm, and these morphologic changes in the anterior visual pathway are correlated with glaucomatous optic nerve damage. MRI of the anterior visual pathway may be a good tool for evaluating glaucomatous damage objectively.

Adult↗

Molecular and cellular reactions of retinal ganglion cells and retinal glial cells under centrifugal force loading.

PURPOSE: To investigate changes in retinal ganglion cell (RGC) survival and morphology, retinal glial cell effects on RGC survival, and changes in mRNA expression during centrifugal force loading using a newly developed device. METHODS: Changes in RGC survival and morphology were examined when isolated RGCs from 2-day-old rats were loaded with centrifugal force equivalent to 16, 28, or 33 mm Hg. The effects of cocultured retinal glial cells on RGC survival were studied in the presence of centrifugal force equivalent to 16 and 28 mm Hg for 48 hours. The microarray method and real-time polymerase chain reaction confirmed changes in mRNA expression when RGCs and retinal glial cells were loaded with centrifugal force equivalent to 28 mm Hg for 24 hours. RESULTS: The survival of isolated RGCs and the number of neurites were significantly decreased by centrifugal force loading. Conversely, there was no significant change in the survival of isolated retinal glial cells. The survival of cocultured RGCs was significantly better than that of isolated RGCs. In contrast to the numerous changes in the mRNA expression of retinal glial cells subjected to centrifugal force loading, there was no significant change in the mRNA expression of RGCs. CONCLUSIONS: The developed device may have potential for use as an in vitro model of RGC damage. The response to centrifugal force loading varies according to cell type, and the marked changes in the mRNA expression of retinal glial cells may be involved in the improvement of RGC survival.

Animals↗

[Reliable parameters for assessing the birefringence of retinal nerve fiber layer under various conditions of corneal birefringence].

PURPOSE: To find a reliable parameter for the assessment of parafoveal nerve fiber layer using scanning laser polarimetry. METHODS: The retinal nerve fiber layer was imaged using a Nerve Fiber Analyzer II (NFA II) along the parafoveal circle with a 90-pixel diameter in 4 dilated eyes of 4 normal subjects. The average thickness was measured in the superior(S), temporal(T), inferior(I), and nasal(N) quadrants. The image was obtained by means of a laser beam passing through 4 different locations in the cornea: the center, 2 mm temporal from the center, 2 mm lower temporal from the center, and 2 mm lower from the center. RESULTS: The circumference profile of the nerve fiber layer around the fovea showed a biphasic pattern similar to that obtained around the optic disc. However, the peaks of the pattern varied according to the corneal location through which the laser beam passed. Accordingly, the average thickness of the nerve fiber layer in each quadrant showed great fluctuation when using a displaced laser beam. The coefficient of variance was large (0.265-0.313) for the nerve fiber layer thickness itself; however, it was far less for the ratio of the nerve fiber layer thickness in the opposite direction, such as temporal-to-nasal (0.082) or superior-to-inferior (0.089). CONCLUSIONS: Although the measurement of the retinal nerve fiber thickness itself depends largely on the location in the birefringent cornea through which the laser beam passes, the ratios of nerve fiber layer thickness such as temporal-to-nasal or superior-to-inferior are reliable and show less fluctuation in the measured values.

Adolescent↗

The association between Japanese primary open-angle glaucoma and normal tension glaucoma patients and the optineurin gene.

Glaucoma represents one of the most common eye diseases and is characterized by progressive loss of visual fields. In the more advanced stages bilateral blindness may result, due to optic nerve atrophy and an excavated optic nerve head. Open-angle glaucoma is one of the main disease subsets, which may be further divided into high tension primary open-angle glaucoma (POAG) and normal tension glaucoma (NTG). Recently, the optineurin ( OPTN) gene was identified as a causative factor for NTG. Alterations in this gene were found in Caucasian families with NTG. In particular, c.458G>A, c.691-692insAG and c.1944G>A were shown to be risk factors. Since NTG is reported to be the most common form of glaucoma in Japan, and to identify if the OPTN gene plays a role in POAG, the DNAs from 148 unrelated Japanese patients with NTG, 165 patients with POAG and 196 unrelated controls who were not suffering glaucoma were investigated by appropriate genotyping techniques. No glaucoma-specific mutations were found in the OPTN gene in Japanese glaucoma patients. However, some novel single-nucleotide polymorphisms (SNPs) in the exons and introns are reported in this paper for the first time.

Adult↗

Differences in nitric oxide production: a comparison of retinal ganglion cells and retinal glial cells cultured under hypoxic conditions.

The aim of this study was to compare the effects of hypoxia on nitric oxide synthase (NOS) expression and the production of NO between isolated retinal ganglion cells (RGCs) and retinal glial cells. Reverse transcription-polymerase chain reaction (RT-PCR) was employed to examine the presence of neuronal NOS mRNA, inducible NOS mRNA, and endothelial NOS mRNAs in the two cell types. RGCs and retinal glial cells were separately cultured under hypoxic (10% O(2)) or control (20% O(2)) conditions. Changes in NOS-mRNA expression were quantified by real-time PCR, and nitrite in the medium was measured up to 96 h of culture. The effects of non-NOS- and iNOS-selective inhibitors on hypoxia-induced release of nitrite in the culture medium were evaluated. RT-PCR revealed the presence of three types of NOSs in the two types of cultured cells. Hypoxic culture conditions significantly changed the expression of all NOS mRNAs in retinal glial cells but not in RGCs. NO production showed significant changes corresponding to those of NOS mRNAs in retinal glial cells but not in RGCs, and both NOS inhibitors significantly reduced hypoxia-induced nitrite release in retinal glial cells. Retinal glial cells but not RGCs may be the major source of NO under hypoxic conditions.

Animals↗

Increase in dephosphorylation of the heavy neurofilament subunit in the monkey chronic glaucoma model.

PURPOSE: To investigate the phosphorylation of the heavy neurofilament subunit (NF-H), which could be deeply involved in axonal transport of retinal ganglion cells (RGCs), in an experimental glaucoma model of chronic elevation of intraocular pressure (IOP) in monkeys. METHODS: One eye in adult monkeys was randomly selected for laser treatment, and IOP was maintained between 30 and 40 mm Hg throughout the experiment. The eyeballs with the optic nerve and optic chiasm were enucleated as one tissue and were subject to immunocytochemical observation, using two NF-H-specific antibodies, NF-200 and SMI31. NF-200 reacts with both phosphorylated and dephosphorylated NF-H, whereas SMI reacts only with phosphorylated NF-H. Ratios of SMI31-positive to NF-200-positive areas were calculated for quantitative evaluation of phosphorylation status. Specimens from the retina, lamina cribrosa (LC), post-LC, and optic chiasm were evaluated separately. Phosphorylation of NF-H at the retina and optic nerve head was compared between specimens from temporal retina and nasal retina, or between temporal and nasal regions of the optic disc. The status of phosphorylation was confirmed by Western blot analysis. RESULTS: An enlargement of the disc cup was observed on the temporal side, and the superior and inferior poles were preferentially involved in the neuronal damage in laser-treated eyes. Most NF-Hs in the control eyes were phosphorylated in all investigated regions, whereas those in the glaucomatous eyes were significantly dephosphorylated, and NF-Hs in the temporal region were significantly dephosphorylated compared with those in the nasal region. At the optic chiasm, NF-Hs in axons traveling from laser-treated eyes were highly dephosphorylated, and the extent of NF-H dephosphorylation corresponded to the degree of glaucoma-induced axonal damage. Western blot analysis showed the change in the phosphorylation of NF-Hs. CONCLUSIONS: NF-Hs in RGC axons are dephosphorylated by elevated IOP, which may be deeply involved in glaucoma-induced damage to axonal transport.

Animals↗

[21st century management of glaucoma].

According to a recent epidemiological study done in Japan, 2 or 3 million Japanese people are thought to be suffering from glaucoma, and 70-80% of them have not been examined or diagnosed by ophthalmologists. Therefore, the problem is how to find these untreated and undiagnosed people. At present, treatment of glaucoma continues to be directed at lowering intraocular pressure to prevent progression of glaucomatous optic neuropathy. However, theoretically, there are three stages in the prevention of progression of glaucoma. In the first stage, diagnosis of glaucoma can be done by genetic examination, before occurrence of glaucoma. The MYOCILIN/trabecular meshwork-inducible glucocorticoid response gene and the optineurin gene were identified as the genes that cause open angle glaucoma. Although some Japanese patients have sequence changes in the myocilin gene, there are no apparent specific mutations in Japanese glaucoma patients, in the MYOCILIN/TIGR and optineurin genes. Secondary glaucoma such as steroid glaucoma, induced by allergic diseases, and neovascular glaucoma, induced by retinal circulatory insufficiency, are preventable by improving the causal diseases, diabetes and hypertension. The education of doctors and laymen is important to reduce the occurrence of diabetes, and hypertension to prevent diabetic retinopathy, and retinal vessel occlusion. The second stage in preventing progression of glaucoma is to find the disease as early as possible. In Japan, a physical examination system is in place for everybody over 40 years old, in companies and local districts. Therefore, ocular examination, specially non-mydriatic fundus photographs should be taken in these examinations, and the film should be evaluated by an ophthalmologist, to search for retinal and optic disc abnormalities. Primary open angle glaucoma can be detected through this system in early stages. In primary angle closure glaucoma, instruments for estimating anterior chamber rapidly and accurately are necessary for the diagnosis. There is a special machine which can be handled easily, safely, and economically for detecting angle closure glaucoma, has been developed by Yamanashi University. This machine might help to reduce the number of angle closure glaucoma patients in the world. In the near future, a glaucoma network system should be put in place all over Japan. This organization consists of central headquarter and local central office. Most hospitals and private offices will belong to a local central office, and several glaucoma specialists will work in central and local offices. All glaucoma patients will be registered in local glaucoma office. The information on glaucoma patients will be communicated in the system the through light fiber cables or a satellite system. The patients can ask about their own disease through this glaucoma center system. In the third stage of glaucoma prevention, progression of glaucomatous optic neuropathy is retarded by conventional IOP lowering treatment or neuroprotective drugs. This stage compromises rehabilitation of visual function, implant of artificial visual systems, and regeneration of retinal ganglion cells(RGC). The disturbances of axonal flow in guinea pig optic nerve fibers was demonstrated electromicroscopically by quick-freeze, deep-etching method and, the decrease in numbers of motor proteins like "Kinesin" "Dynein" and "MAP-1" was shown in guinea pig eyes with elevated intraocular pressure by immunohistochemistry. Retinal glanglion cells have been isolated and new findings have been reported using this RGC culture system. Therefore, new neuroprotective drugs will be developed through this culture system.

Animals↗

Comparison between isopropyl unoprostone and latanoprost by prostaglandin E(2)induction, affinity to prostaglandin transporter, and intraocular metabolism.

The pharmacological differences between isopropyl unoprostone (referred to as unoprostone) and latanoprost, concerning their induction of endogenous prostaglandin E(2)(PGE(2)) and affinity to a human prostaglandin transporter (PGT), were investigated. Freshly dissected bovine iris tissues were incubated with major intraocular metabolites of unoprostone, M1 and M2, acid of latanoprost, or PGF(2 alpha), and PGE(2)induction was measured. Affinities of M1, M2, latanoprost, acid of latanoprost, and PGF(2 alpha)to PGT molecule were measured using PGT-cDNA transfected HeLa cells by an isotopic influx assay.(3)H-unoprostone was incubated with freshly prepared serum, aqueous humor, or frozen stored fetal bovine serum (FBS), and the radioactivity of supernatants was measured to investigate their metabolism of(3)H-unoprostone.M2, acid of latanoprost, and PGF(2 alpha)significantly increased a release of PGE(2)compared with the control. 10 microM indomethacin completely inhibited PGE(2)induction by acid of latanoprost and PGF(2 alpha), while 100 microM indomethacin was required to inhibit PGE(2)induction completely by M1 and M2. Unoprostone, M1, M2, and latanoprost showed little affinity to PGT, while acid of latanoprost had an affinity to PGT. Freshly prepared serum and aqueous humor metabolized unoprostone, but frozen stored FBS did not. The release of endogenous PGE(2)may play an important role of action by means of PG analogs, and differences in indomethacin-related inhibition of PGE(2)release and in affinities to PGT may in part cause their different actions.

Adult↗

Effects of isopropyl unoprostone and latanoprost on melanogenesis in mouse epidermal melanocytes.

PURPOSE: The authors sought to investigate the cellular mechanism of melanogenesis by prostaglandin antiglaucomatous compounds, isopropyl unoprostone (referred to as unoprostone) and latanoprost, and to quantitatively compare their effect on melanogenesis using cultured mouse epidermal melanocytes. METHODS: M1, M2, and the acid of latanoprost, all of which are possible intraocular metabolites of unoprostone or latanoprost, were used. Tested prostaglandin-related compounds (final concentration range, 1 micromol/L-10 nmol/L) were administrated to the culture medium of purely cultured mouse melanoblasts, melan-A, once daily for 2 weeks. One micromole per liter prostaglandin F(2 alpha) solution was administered in parallel. Radioisotope assays were used to measure the total melanin synthesis and the activity of tyrosinase in converting tyrosine to L-3,4-dihydroxyphenylalanine, which is a rate-limiting reaction in melanogenesis. The effects of prostaglandin F(2 alpha), M1, or M2 on proliferation of melan-A were examined. RESULTS: M1, M2, and acid of latanoprost but not prostaglandin F(2 alpha), significantly enhanced tyrosinase activity. M2 and acid of latanoprost more greatly enhanced tyrosinase activity than did M1. None of the tested compounds significantly altered the proliferation and total melanin synthesis of melan-A. CONCLUSIONS: Both unoprostone and latanoprost enhanced tyrosinase activity. These prostaglandin-related compounds may influence the nature of melanin and result in pigmentation.

Animals↗

Neuroprotective effects of nipradilol on purified cultured retinal ganglion cells.

PURPOSE: To investigate effects of nipradilol, a nonselective beta- andbgr;-and selective alpha1-receptor antagonist and a potential nitric oxide releaser, on retinal ganglion cells purified and cultured in a serum-free medium. METHODS: Retinal ganglion cells were isolated from 2-day-old Sprague-Dawley rats by means of two-step panning. A series of nipradilol (10(-5), 10(-6), 10(-7), 10(-8), 10(-9), and 10(-10)-mol/L) or vehicle solutions were administered to the culture medium for 48 hours, and the survival rate of retinal ganglion cells was evaluated using a newly developed system that evaluates the survival rate in small and large retinal ganglion cells separately. The effects of timolol maleate or bunazosin (10(-5), 10(-6), 10(-7), and 10(-8) -mol/L) solutions on retinal ganglion cells survival were also evaluated. The survival rate was evaluated after 10(-5)-mol/L c-PTIO (2-[4-carboxyphenyl]-4,4,5,5 tetramethylimidazoline-1-oxyl-3-oxide potassium salt), a nitric oxide scavenger, was administered to retinal ganglion cells with 10(-5)-mol/L nipradilol. RESULTS: Nipradilol significantly increased the survival rate of both small and large retinal ganglion cells in a concentration-dependent manner compared with the controls. The maximum survival rate improvement of small and large retinal ganglion cells was 29.1% and 14.5%, respectively. Although timolol maleate and bunazosin did not affect the survival rate, 10(-5)-mol/L c-PTIO significantly inhibited the nipradilol-induced survival rate improvement by 69.9% in small retinal ganglion cells and by 91.6% in large retinal ganglion cells. CONCLUSION: Nipradilol improves the survival rate of cultured postnatal rat retinal ganglion cells, and the nitric oxide generated from nipradilol may contribute to this effect.

Adrenergic alpha-Antagonists↗