Hiromu K. Mishima

Intravitreal levels of vascular endothelial growth factor and interleukin-6 are correlated with macular edema in branch retinal vein occlusion

BackgroundTo investigate whether vascular endothelial growth factor (VEGF) or interleukin-6 (IL-6) contributes to the pathogenesis of macular edema in eyes with branch retinal vein occlusion (BRVO), the correlations between these factors were investigated.MethodsWe studied 25 patients suffering from macular edema with BRVO and 14 patients with nonischemic ocular disease (control group). The degree of retinal ischemia was evaluated in terms of the area of capillary nonperfusion using Scion Images, and the severity of macular edema was examined using optical coherence tomography. Vitreous fluid samples were obtained at the time of vitreoretinal surgery, and VEGF and IL-6 levels in the vitreous fluid and plasma were determined by means of enzyme-linked immunosorbent assays.ResultsVitreous fluid levels of VEGF and IL-6 were significantly elevated in patients with BRVO compared with control patients (P=0.0011 and P<0.0001, respectively). Also, the vitreous level of VEGF was significantly correlated with that of IL-6 (P=0.0012), and vitreous levels of VEGF and IL-6 were correlated with the size of the BRVO nonperfusion area (P<0.0001 and P=0.0033, respectively). Furthermore, vitreous levels of VEGF and IL-6 were correlated with the severity of macular edema (P=0.0008 and P=0.0191, respectively) and the severity of macular edema of BRVO was significantly correlated with the size of the BRVO nonperfusion area (P=0.0044).ConclusionsThe levels of VEGF and IL-6 are increased in patients with macular edema with BRVO and are significantly correlated with the size of the nonperfusion area and the severity of macular edema. Therefore, they may play a role in macular edema with BRVO.

Aqueous humour levels of cytokines are correlated to vitreous levels and severity of macular oedema in branch retinal vein occlusion

AimTo investigate whether the aqueous levels of vascular endothelial growth factor (VEGF) and interleukin-6 (IL-6) are correlated to the vitreous levels of these substances and to the severity of macular oedema in branch retinal vein occlusion (BRVO).MethodsAqueous and vitreous samples were obtained during cataract and vitreous surgery from 24 patients (24 eyes) with macular oedema in BRVO. The VEGF and IL-6 levels in aqueous humour, vitreous fluid, and plasma were determined by enzyme-linked immunosorbent assay. The degree of retinal ischaemia was evaluated in terms of the area of capillary nonperfusion using the Scion Image. The severity of macular oedema was evaluated using the OCT.ResultsThe aqueous level of VEGF was significantly correlated with the vitreous level of VEGF (P<0.0001). Vitreous levels of VEGF and IL-6 were significantly correlated with the nonperfusion area of BRVO (P<0.0001, P=0.0061, respectively), as were the aqueous levels of VEGF and IL-6 (P<0.0001, P=0.0267, respectively). Furthermore, the vitreous levels of VEGF and IL-6 and the aqueous level of VEGF were significantly correlated with the severity of macular oedema of BRVO (P=0.0001, P=0.0331, P=0.0272, respectively).ConclusionOur results suggest that the aqueous level of VEGF may reflect its vitreous level. Measurement of the aqueous level of VEGF may be clinically useful to indicate the severity of macular oedema with BRVO.

High frequency of open-angle glaucoma in Japanese patients with Alzheimer's disease

The clinical and genetic relationships between Alzheimers disease (AD) and glaucoma remain obscure. The aim of this study was to determine the prevalence of open-angle glaucoma (OAG) in patients with AD and whether the apolipoprotein E (APOE) 4 allele is associated with AD, with or without OAG, in Japanese. The groups consisted of 172 patients with the diagnostic criteria of AD and 176 age-matched controls. Ophthalmic examinations were conducted, and genomic analysis was performed by PCR and digestion of products with an enzyme. OAG was found in 41 (23.8%) of the AD patients, which was a significantly (p = 0.0002) higher prevalence than that in the controls (9.9%). Furthermore, there was no significant difference between intraocular pressures (IOPs) in AD patients with OAG and without OAG. The percentage of AD patients who carried an APOE epsilon4 allele (29.5%) was significantly (p = 0.0007) higher than that of the controls (9.1%). However, the percentage of AD patients with OAG who carried an APOE epsilon4 allele (35.7%) was not significantly different than that of AD patients without OAG (27.7%, p = 0.42). In summary, the prevalence of OAG is high in Japanese patients with AD, suggesting that common factors other than APOE may contribute to the two diseases.

Postoperative Cataract Cases among Atomic Bomb Survivors: Radiation Dose Response and Threshold

Abstract Neriishi, K., Nakashima, E., Minamoto, A., Fujiwara, S., Akahoshi, M., Mishima, H. K., Kitaoka, K. and Shore, R. E. Postoperative Cataract Cases among Atomic Bomb Survivors: Radiation Dose Response and Threshold. Radiat. Res. 168, 404–408 (2007). Recent evidence argues against a high threshold dose for vision-impairing radiation-induced cataractogenesis. We conducted logistic regression analysis to estimate the dose response and used a likelihood profile procedure to determine the best-fitting threshold model among 3761 A-bomb survivors who underwent medical examinations during 2000–2002 for whom radiation dose estimates were available, including 479 postoperative cataract cases. The analyses indicated a statistically significant dose–response increase in the prevalence of postoperative cataracts [odds ratio (OR), 1.39; 95% confidence interval (CI), 1.24–1.55] at 1 Gy, with no indication of upward curvature in the dose response. The dose response was suggestive when the restricted dose range of 0 to 1 Gy was examined. A nonsignificant dose threshold of 0.1 Gy (95% CI, <0–0.8) was found. The prevalence of postoperative cataracts in A-bomb survivors increased significantly with A-bomb radiation dose. The estimate (0.1 Gy) and upper bound (0.8 Gy) of the dose threshold for operative cataract prevalence was much lower than the threshold of 2–5 Gy usually assumed by the radiation protection community and was statistically compatible with no threshold at all.

Circadian intraocular pressure management with latanoprost: diurnal and nocturnal intraocular pressure reduction and increased uveoscleral outflow.

Based on their mechanism of action, the most frequently used ocular hypertensive agents, the beta-blockers, cannot be assumed to reduce IOP during sleep. The need for drugs that reduce IOP around-the-clock is underscored, however, by the fact that inadequate nocturnal ocular perfusion pressure is considered to be one of the likely causes of glaucomatous optic neuropathy especially in some cases of normal tension glaucoma. The studies reviewed here demonstrate that latanoprost, a new ocular hypotensive prostaglandin F2 alpha analogue, applied once a day at a concentration of 0.005%, maintains a statistically highly significant IOP reduction around-the-clock. The magnitude of this IOP reduction was found to be essentially identical during the day and at night, both in patients maintained on timolol and in those not receiving other glaucoma medication. Latanoprost-induced IOP reduction was also found to be associated with increased uveoscleral outflow in normotensive volunteers, both during the day and at night. These circadian studies suggest that this new ocular hypotensive agent can be expected to be particularly useful for the medical management of some forms of glaucoma, such as normal tension glaucoma, when the cause of the glaucomatous damage cannot be linked specifically to diurnal IOP abnormalities.

Proteome Analysis of Human Vitreous Proteins

Purpose: Various protein contents such as enzymes, growth factors, and structural components are responsible for biological activities in organs. We have created a map of vitreous proteins and developed a proteome analysis of human vitreous samples to understand the underlying molecular mechanism and to provide clues to new therapeutic approaches in eyes with proliferative diabetic retinopathy (PDR). Methods: Vitreous and serum samples were obtained from subjects with idiopathic macular hole (MH, 26 cases) and PDR (33 cases). The expressed proteins in the samples were separated by two-dimensional (2-D) polyacrylamide gel electrophoresis. Protein spots were visualized by silver staining, and their expression patterns were analyzed. Some protein spots of concern were excised from the 2-D gels, digested in situ with trypsin, and analyzed by mass spectrometry. Results: More than 400 spots were detected on 2-D gels of MH cases, of which 78 spots were successfully analyzed. The spots corresponded to peptide fragments of 18 proteins, including pigment epithelium-derived factor, prostaglandin-D2 synthase, and interphotoreceptor retinoid-binding protein. These were not identified in the corresponding serum samples. These proteins were also expressed in PDR samples, with no distinct tendency to increase or decrease compared with the MH samples. More than 600 spots were detected on 2-D gels of PDR cases, of which 141 spots were successfully analyzed. The spots corresponded to peptide fragments of 38 proteins. Enolase and catalase were identified among four detected spots. Neither was found in MH vitreous or in PDR serum samples. Conclusion: A map of protein expression was made in human vitreous from eyes with MH and PDR. In the PDR eyes, the increased protein expression observed was due to barrier dysfunction and/or production in the eye. Proteome analysis was useful in systematic screening of various protein expression in human vitreous samples.

Attenuation by PACAP of glutamate-induced neurotoxicity in cultured retinal neurons

The effects of pituitary adenylate cyclase activating polypeptides (PACAPs: PACAP27, PACAP38) on glutamate-induced neurotoxicity were examined using cultured retinal neurons obtained from 3- to 5-day old Wistar rats. Cell viability was evaluated by double staining with fluorescein diacetate and propidium iodide. Effects of PACAPs on the increase in intracellular Ca(2+) concentration ([Ca(2+)](i)) in retinal neurons was investigated using the Ca(2+) image analyzing system with fura-2. The cAMP contents and the mitogen-activated protein (MAP) kinase activity in retinal cultures were measured by radioimmunoassay. Concomitant application of PACAPs (10 nM-1 microM) with glutamate (1 mM) for 10 min inhibited the delayed death of retinal neurons, which was observed 24 h after glutamate (1 mM) treatment in a dose-dependent manner. Protection by PACAPs (100 nM) against glutamate-induced neurotoxicity was antagonized by PACAP6-38 (1 microM), a PACAP antagonist, and H-89 (1 microM), a protein kinase A (PKA) inhibitor. However, PACAPs did not affect the glutamate-induced increase in [Ca(2+)](i), but PACAPs (1-100 nM) increased the cAMP levels in a dose-dependent manner. In addition, activation of MAP kinase by PACAP38 (1 microM) was inhibited by simultaneous application with H-89 (1 microM). These findings suggest that PACAPs attenuate glutamate-induced delayed neurotoxicity in cultured retinal neurons by activating MAP kinase through the activation of cAMP-stimulated PKA.

No Association Of Complement Factor H Gene Polymorphism And Age-related Macular Degeneration In The Japanese Population

Purpose: The aim of this study was to determine whether genetic polymorphism of complement factor H (CFH) is associated with age-related macular degeneration (AMD) in the Japanese population. Methods: Genomic DNA was examined in a cohort of 67 Japanese patients with AMD and 107 controls. TT/TC/CC genotypes on exon 9 were screened for sequence alternation by polymerase chain reaction analysis and through sequencing. Results: The mean ages ± SD of AMD patients and control subjects were 73 ± 8.5 years and 72 ± 8.7 years, respectively. There was no significant difference between CFH genotypes in the AMD group (TT, 76%; TC, 19%; CC, 5%) and the control group (TT, 80%; TC, 17%; CC, 3%). The frequencies of T and C alleles were 86% and 14%, respectively, in the AMD group and 89% and 11%, respectively, in the control group. Conclusion: CFH gene polymorphism is not associated with AMD in the Japanese population. Moreover, the frequency of the C allele is low among the Japanese population.

Neuroprotective effects of erythropoietin on glutamate and nitric oxide toxicity in primary cultured retinal ganglion cells

Erythropoietin receptor (EpoR) is expressed in the central nervous system (CNS), however, no clear consensus has been obtained whether Epo acts as a prosurvival factor in neurons. Because retinal ganglion cell (RGC) death is a common cause of reduced visual function in several ocular diseases, we explored whether Epo might potentially be beneficial in protecting RGCs from glutamate and nitric oxide (NO)-induced cytotoxicity, using isolated RGCs by a two-step panning method. Brain-derived neurotrophic factor (BDNF) was used as a positive control. EpoR mRNA was expressed in isolated RGCs, and EpoR protein was expressed on the RGCs in the normal and ischemic retinas. Epo had less potential to improve the survival of primary RGCs in serum-free medium than BDNF. In these cells, BDNF, but not Epo, downregulated the expression of Bim, a proapoptotic Bcl-2 family member that plays a key role in cytokine-mediated cell survival, suggesting a possible mechanism for this difference. When RGCs were cultured with glutamate or an NO-generating reagent, the survival of RGCs was compromised, and Bcl-2 expression was decreased in these cells. Both Epo and BDNF significantly reduced RGC death induced by glutamate and NO. In agreement with this, these factors reversed the Bcl-2 expression. These findings suggest that Epo may be a potent neuroprotective therapeutic agent for the treatment of ocular diseases that are characterized by RGC death.

A role for RAD54B in homologous recombination in human cells

In human somatic cells, homologous recombination is a rare event. To facilitate the targeted modification of the genome for research and gene therapy applications, efforts should be directed toward understanding the molecular mechanisms of homologous recombination in human cells. Although human genes homologous to members of the RAD52 epistasis group in yeast have been identified, no genes have been demonstrated to play a role in homologous recombination in human cells. Here, we report that RAD54B plays a critical role in targeted integration in human cells. Inactivation of RAD54B in a colon cancer cell line resulted in severe reduction of targeted integration frequency. Sensitivity to DNA‐damaging agents and sister‐chromatid exchange were not affected in RAD54B‐deficient cells. Parts of these phenotypes were similar to those of Saccharomyces cerevisiae tid1/rdh54 mutants, suggesting that RAD54B may be a human homolog of TID1/RDH54. In yeast, TID1/RDH54 acts in the recombinational repair pathway via roles partially overlapping those of RAD54. Our findings provide the first genetic evidence that the mitotic recombination pathway is functionally conserved from yeast to humans.