TRIAMCINOLONE ACETONIDE–ASSISTED PARS PLANA VITRECTOMY IMPROVES RESIDUAL POSTERIOR VITREOUS HYALOID REMOVAL

OBJECTIVE

To determine whether triamcinolone acetonide (TA) can facilitate residual posterior vitreous hyaloid removal in pars plana vitrectomy (PPV), we examined the ultrastructure of inner limiting membrane (ILM) removed in TA-assisted PPV for diabetic macular edema (DME).

PATIENTS AND METHODS

In this retrospective series of 38 eyes of 37 patients who underwent PPV and ILM removal for diffuse DME with posterior hyaloid attachment, 24 eyes underwent standard PPV without TA (control group), and 14 eyes underwent TA-assisted PPV (TA group). Excised ILMs during PPV were examined by transmission electron microscopy (control group, n = 20; TA group, n = 10) or scanning electron microscopy (control group, n = 4; TA group, n = 4).

RESULTS

Transmission electron microscopy clearly demonstrated that the ratio of the posterior vitreous hyaloid remaining on ILM was significantly lower (P = 0.0187) in the TA group than in the control group and also that TA-assisted PPV successfully removed posterior hyaloid in five of seven eyes with TA granules remaining on the retinal surface even after surgical separation of the posterior vitreous. Scanning electron microscopy enabled spatial analysis of the residual posterior hyaloid on ILM, which appeared in a patchy fashion in the control group.

CONCLUSIONS

TA-assisted PPV clearly demonstrated the residual posterior hyaloid on ILM and allowed more efficient removal of the posterior hyaloid than standard PPV.

Interleukin-18 regulates pathological intraocular neovascularization

Recently, the proinflammatory cytokine IL-18 has been shown to have a role in angiogenesis. This study aimed to elucidate its role in abnormal neovascularization (NV) in an oxygen-induced retinopathy (OIR) mouse model of the retinopathy seen in human premature newborns. IL-18 was constitutively expressed in the retina in C57BL/6 mice, but expression transiently dropped on Day 17 after birth in mice exposed to 75% oxygen for 5 days between Days 7 and 12. Coincident with the IL-18 reduction in oxygen-treated mice, vascular endothelial growth factor was expressed in the retina, and OIR developed. By Day 24, NV in the retina had regressed to normal levels. By contrast, IL-18 knockout mice, exposed to elevated oxygen concentrations, developed more severe OIR on Day 17, and it is important that this persisted until Day 24. This suggested that IL-18 negatively regulated retinal NV. To investigate this further, we administrated recombinant IL-18 to C57BL/6 mice during the development of OIR but found no significant inhibition of retinopathy. However, when IL-18-binding protein was administered during the OIR recovery phase to neutralize endogenous IL-18, OIR was still apparent on Day 24. We therefore concluded that IL-18 regulates pathogenic retinal NV by promoting its regression rather than inhibiting its development. This suggests some useful, new approaches to treating retinopathy in humans.

Transforming growth factor-beta2 and connective tissue growth factor in proliferative vitreoretinal diseases: possible involvement of hyalocytes and therapeutic potential of Rho kinase inhibitor

The critical association of connective tissue growth factor (CTGF), which is thought to be one of the downstream mediators of transforming growth factor-beta (TGF-beta), with vitreoretinal diseases remains to be clarified. In the current study, we first demonstrated the correlation between the concentrations of TGF-beta2 as well as CTGF in the vitreous and CTGF gene regulation in cultured hyalocytes. Concentrations of TGF-beta2 and CTGF in the vitreous from patients with proliferative vitreoretinal diseases were significantly higher than in those with nonproliferative diseases, and there was a positive correlation between their concentrations (r = 0.320, P < 0.01). Cultured hyalocytes expressed CTGF mRNA, which was enhanced in the presence of TGF-beta2, associated with nuclear accumulation of Smad4. TGF-beta2-dependent Smad4 translocation and CTGF gene expression were mediated through Rho kinase and at least partially via p38 mitogen-activated protein kinase. Finally, fasudil, a Rho kinase inhibitor already in clinical use, inhibited both Smad4 translocation and CTGF gene expression. In conclusion, combined effects of TGF-beta2 and CTGF appear to be involved in the pathogenesis of proliferative vitreoretinal diseases. Hyalocytes may be a possible source of CTGF and thus might play a role in vitreoretinal interface diseases. Furthermore, Rho kinase inhibitors might have therapeutic potential to control fibrotic disorders in the eye.

Preclinical investigation of fluorometholone acetate as a potential new adjuvant during vitreous surgery

OBJECTIVE

To examine the effects of intravitreal fluorometholone acetate (FMT) on the morphology and function of the retina and to investigate its possible use for vitreous surgery.

METHODS

Brown Norway rat eyes (n = 6, 12 groups) were injected with 0.05 ml of SF6 gas for vitrectomization. Four weeks later, FMT solution was injected into the vitreous cavity/subretinal space of the vitrectomized eyes at doses of 10, 20, and 40 mg/ml (0.05 ml/eye, n = 12 for each group). The retinal function was evaluated by electroretinography (ERG) at 4 and 8 weeks after FMT injection. Retinal toxicity was also assessed histologically by a light microscopy. Sham-operated eyes (0.05 ml of irrigating solution, n = 12) were used as control animals. FMT-assisted pars plana vitrectomy with internal limiting membrane (ILM) peeling was performed in primate eyes (n = 2). Retinal toxicity was assessed by ophthalmoscope, fluorescein angiography and electron microscopy three months after the vitreous surgery.

RESULTS

There was no remarkable reduction in any ERG waves at either time interval at 4 and 8 weeks after the intravitreal/subretinal injection of FMT. No obvious histological change was observed in any of the rat eyes either. Using ophthalmoscope, fluorescein angiography and electron microscopy, the appearance of the primate retinas remained to be in a non-pathological condition.

CONCLUSION

FMT appears to be a potentially useful tool in assisting vitreous surgery including safe ILM peeling.

Antimalarial activity of some Colombian medicinal plants

Antimalarial activity of 10 vegetal extracts (9 ethanolic extracts and 1 crude alkaloid extract), obtained from eight species traditionally used in Colombia to treat malaria symptoms, was evaluated in culture using Plasmodium falciparum chloroquine resistant (FcB2) strain and in vivo on rodent malaria Plasmodium berghei. The activity on ferriprotoporphyrin biomineralization inhibition test (FBIT) was also assessed. Against Plasmodium falciparum, eight extracts displayed good activity Abuta grandifolia (Mart.) Sandwith (Menispermaceae) leaves, Acacia farnesiana (L.) Willd. (Mimosaceae) leaves, Acnistus arborescens (L.) Schltdl. (Solanaceae) aerial part, Croton leptostachyus Kunth (Euphorbiaceae) aerial part, Piper cumanense Kunth (Piperaceae) fruits and leaves, Piper holtonii C. DC. (Piperaceae) aerial part and Xylopia aromatica (Lam.) Mart. (Annonaceae) bark with IC(50) values ranging from <1 to 2.1 microg/ml, while in the in vivo model only Abuta grandifolia alkaloid crude extract exhibits activity, inhibiting 66% of the parasite growth at 250 mg/kg/day. In the FBIT model, five extracts were active (Abuta grandifolia, Croton leptostachyus, Piper cumanense fruit and leaves and Xylopia aromatica).

Brilliant blue G selectively stains the internal limiting membrane/brilliant blue G-assisted membrane peeling

PURPOSE

To report the use of the dye brilliant blue G (BBG) for staining of the internal limiting membrane (ILM) during macular hole (MH) and epiretinal membrane (ERM) surgery.

METHODS

This study was designed as an interventional, noncomparative, prospective, clinical case series. Twenty eyes from 20 consecutive patients with MH or ERM underwent BBG-assisted ILM and ERM removal. In MH cases, a posterior vitreous detachment was created, followed by the injection of 0.25 mg/mL BBG solution into the vitreous cavity and immediate washout of the BBG. This technique improved visualization of the ILM, enabling peeling and surgery to be performed successfully. However, in ERM cases, staining of the ERM could not be confirmed at this concentration. Finally, the ILM including the ERM was removed in all cases. Preoperative and postoperative ophthalmic examinations were performed.

RESULTS

Postoperatively, 17 patients (85%) had visual acuity improved by at least 2 Snellen lines. No adverse effects were observed postoperatively during the observation period (mean follow-up +/- SD, 7.3 +/- 1.0 months).

CONCLUSIONS

BBG selectively stains the ILM. This technique can facilitate the management of MH and ERM surgery without any adverse effects, as was shown in this short-term study.

Preclinical investigation of internal limiting membrane staining and peeling using intravitreal brilliant blue G

PURPOSE

To investigate the effects of intravitreal brilliant blue G (BBG) on the morphology and functions of the retina and its possible use for staining and peeling of the internal limiting membrane (ILM).

METHODS

Rat eyes (n = 78) underwent gas compression vitrectomy. BBG solution was then injected into the vitreous cavity. The eyes were enucleated at 2 weeks and 2 months. Light as well as electron microscopy, terminal nick-end labeling staining, and electroretinography (ERG) were used to investigate retinal damage and function. To test the clinical potential of BBG, ILM staining was evaluated in primate eyes after pars plana vitrectomy followed by ILM peeling.

RESULTS

In the rat eyes, no pathologic changes were observed with light microscopy. Electron microscopy revealed that high doses of BBG induced vacuolization in the inner retinal cells, but apoptosis was not detected. There was no reduction in the amplitude of the ERG waves. In the primate eyes, the ILM was clearly visualized after the intravitreous injection of BBG and was peeled off easily from the retina.

CONCLUSIONS

These results demonstrate that BBG, which has low potential for toxicity, high staining ability, and ease of handling, is a good candidate dye for ILM peeling.

Ligand-of-Numb protein X is an endocytic scaffold for junctional adhesion molecule 4

Junctional adhesion molecule 4 (JAM4) is a cell adhesion molecule that interacts with a tight junction protein, membrane-associated guanylate kinase inverted 1 (MAGI-1). Our previous studies suggest that JAM4 is implicated in the regulation of paracellular permeability and the signalings of hepatocyte growth factor. In this study, we performed yeast two-hybrid screening to search for an unidentified JAM4-binding protein and obtained one isoform of Ligand-of-Numb protein X1 (LNX1), LNXp70, that is an interactor of Numb. Ligand-of-Numb protein X1 is expressed in kidney glomeruli and intestinal epithelial cells, where JAM4 is also detected. Immunoprecipitation from kidney lysates supports the in vivo interaction of proteins. Biochemical studies reveal that JAM4 directly binds the second PDZ domain of LNX1 through its carboxyl terminus. Junctional adhesion molecule 4, LNX1 and Numb form a tripartite complex in vitro and are partially colocalized in heterologous cells. Ligand-of-Numb protein X1 facilitates endocytosis of JAM4 and is involved in transforming growth factor beta -induced redistribution of JAM4 in mammary epithelial cells. Experiments using dominant-negative constructs and RNA interference insure that Numb is necessary for the LNX1-mediated endocytosis of JAM4. All these findings indicate that LNX1 provides an endocytic scaffold for JAM4 that is implicated in the reorganization of cell junctions.

Cellular Migration Associated With Macular Hole

OBJECTIVE

To elucidate the pathogenesis of macular hole formation, focusing in particular on the possible role of cellular migration on the cortical vitreous and internal limiting membrane (ILM) around the macular hole.

METHODS

To gain a comprehensive overview of the ILM excised in macular hole surgery (n = 36), the ILMs were carefully unfolded and spread out onto glass slides as continuous flat sheets that each contained a macular hole. The specimens were observed by light microscopy and transmission electron microscopy (n = 9), and the cellular distribution was analyzed by scanning electron microscopy in a quantitative manner (n = 27). Immunohistochemistry for glial fibrillary acidic protein and cytokeratin 18 was carried out for cellular characterization. Cellular proliferation was assessed by immunohistochemistry for proliferating cell nuclear antigen and Ki-67.

RESULTS

Cellular migration was not apparent around the macular hole in the early stage of development of the macular hole (stage 2, 0 microm). As the macular hole passed through the later stages of development, cellular migration developed around the macular hole (stage 3, 84 microm) and the area of cellular migration gradually enlarged (stage 4, 420 microm). The immunophenotypic analysis showed that these cells were mainly glial fibrillary acidic protein-positive glial cells and cytokeratin 18-positive retinal pigment epithelial cells. The proliferating cell nuclear antigen and Ki-67 immunohistochemistry showed that some of these cells were proliferating on the ILM.

CONCLUSIONS

Cellular migration on the ILM is not necessary for the initial formation of a macular break. Cellular migration developed after the macular break occurred, and the migration and proliferation increased gradually from the macular hole.

CLINICAL RELEVANCE

This study provides a new method for understanding the ultrastructural analysis of the pathogenesis of the macular hole.

Staining ability and biocompatibility of brilliant blue G: preclinical study of brilliant blue G as an adjunct for capsular staining

OBJECTIVE

To evaluate the effectiveness and biocompatibility of brilliant blue G (BBG) for capsular visualization for continuous curvilinear capsulorrhexis.

METHODS

The capsular staining ability of BBG was evaluated at graded concentrations of 10.0, 1.0, 0.5, 0.25, 0.1, and 0.01 mg/mL in enucleated pig's eyes. The biocompatibility of BBG was assessed in rat's eyes for 2 months. The eyes were analyzed using light, fluorescence, transmission electron, and scanning electron microscopy. TUNEL (terminal deoxynucleotidyl transferase-mediated biotin-deoxyuridine triphosphate nick-end labeling) was used to detect apoptotic cells, and endothelial cell counts were analyzed using scanning electron microscopy. The results were compared using indocyanine green and trypan blue.

RESULTS

The BBG improved capsular visualization, and a complete capsulorrhexis could be performed. In the rat model, no apparent toxic effect was observed using biomicroscopy during 2 months. Histologically, BBG showed satisfactory biocompatibility. Apoptotic cell death of the endothelial cells was detected in only the trypan blue group. In contrast to BBG, indocyanine green and trypan blue showed degeneration of corneal endothelial cells using transmission and scanning electron microscopy.

CONCLUSION

The BBG contributed to better capsular visualization and caused no apparent complications to the corneal endothelium.Clinical Relevance The BBG is effective and safe capsular staining for continuous curvilinear capsulorrhexis.

Evaluating adjunctive surgical procedures during vitrectomy for diabetic macular edema

PURPOSE

To evaluate the long-term outcomes of adjunctive surgical procedures during pars plana vitrectomy (PPV) for the treatment of diabetic macular edema (DME).

METHODS

In this nonrandomized study, we retrospectively analyzed 57 eyes of 54 patients who had DME and had undergone PPV. We performed PPV using three different surgical procedures: conventional PPV (group PVD; 13 eyes), triamcinolone acetonide (TA)-assisted PPV (group TA; 22 eyes), and TA-assisted PPV combined with internal limiting membrane (ILM) peeling (group ILM; 22 eyes). We also evaluated the preoperative and postoperative best-corrected visual acuity (BCVA) results.

RESULTS

The overall mean preoperative BCVA was 0.86 logarithm of the minimal angle of resolution unit. In groups PVD, TA, and ILM, BCVAs were 0.99, 0.90, and 0.74 (P = 0.310), respectively. The mean postoperative BCVA for all patients improved to 0.68 (P = 0.005). The postoperative BCVA improved in 47% of the treated eyes, it remained unchanged in 37% of the treated eyes, and it deteriorated in 16% of the treated eyes. However, we observed no significant difference in the mean postoperative BCVAs between the three groups. Furthermore, we found that there was no significant difference in postoperative BCVA improvements between any of the groups (P = 0.450).

CONCLUSION

The present study suggests that these 3 PPV approaches do not significantly affect postoperative BCVAs after 18 months of DME treatment.

Critical role of the Rho-kinase pathway in TGF-beta2-dependent collagen gel contraction by retinal pigment epithelial cells

Retinal pigment epithelial cells (RPEs) are thought to be one of the main components of fibrous membrane observed in eyes with proliferative vitreo-retinopathy. We investigated the signalling mechanisms of TGF-beta2-dependent collagen gel contraction by RPEs. An in vitro type I collagen gel contraction assay was performed to evaluate the effect of TGF-beta2 on gel contraction. The expression of alpha-smooth muscle actin (alpha-SMA) and the phosphorylation state of myosin light chain (MLC) were analyzed by Western blotting. The involvement of protein kinases such as p44/42 mitogen-activated protein kinase (MAPK), protein kinase C (PKC), p38 MAPK and phosphatidylinositol-3 kinase was investigated. The contribution of Rho-kinase and/or MLC-kinase was also evaluated using respective kinase inhibitors (Y27632, hydroxyfasudil and ML7). Additionally, RPEs were immunostained to examine whether the expression of alpha-SMA detected in our western blotting correlated to the stress fiber formation within the cells. TGF-beta2 caused time (0-5 days)-and dose (0 10 ng ml(-1))-dependent gel contraction associated with overexpression of alpha-SMA and phosphorylation of MLC (p < 0.01, respectively). PKC inhibitor (GF109203X, 5 microM) and p38 MAPK inhibitor (SB203580, 10 microM) significantly attenuated TGF-beta2-elicited gel contraction via partial downregulation of both alpha-SMA expression and MLC phosphorylation (p < 0.01, respectively). The gel contraction was prominently inhibited in the presence of Y27632 (10 microM) or hydroxyfasudil (10 microM) with strong suppression of MLC phosphorylation but had no significant effect on alpha-SMA expression. Treatment with ML7, in contrast, resulted in a marginal inhibition of MLC phosphorylation and gel contraction. Finally, pretreatment of the cells with Y27632 or hydroxyfasudil prevented the formation of stress fiber within the cells. These results indicate that TGF-beta2-dependent myofibroblastic transdifferentiation and MLC phosphorylation by RPEs involve both PKC and p38 MAPK pathways at least in part. Myofibroblastic transdifferentiation of RPEs appears to be independent of the Rho-kinase pathway, and the presence of alpha-SMA does not necessarily reflect the contractile potential of a cell. While Rho-kinase inhibitors are incapable of preventing myofibroblastic transdifferentiation itself, this pathway could be one of the critical targets of cell-mediated contraction of the tissue containing fibrillar collagens by transdifferentiated RPEs.

Rehabilitation of a bilateral maxillectomy patient with a free fibula osteocutaneous flap*

Rehabilitation of patients who have undergone bilateral maxillectomy is difficult because of extensive loss of bone and soft tissue. In this clinical report, prosthodontic rehabilitation of oral function in a bilateral maxillecitomy patient combined with a new fibular osteocutaneous flap, which was designed to have two oronasal slits for the retention of an obturator prosthesis, was described. A 58-year-old man with a maxillary alveolar carcinoma underwent bilateral maxillectomy. The defect was reconstructed using a vascularized fibular bone wrapped circumferentially with a peroneal flap, which was fixed with miniplates between the right malar prominence and cut edge of the left zygoma remaining two slits anterior and posterior to the graft. Two and half weeks after the surgery, a delayed surgical obturator was delivered and an obturator prosthesis was delivered 6 weeks after the surgery. This obturator prosthesis could be extended into the slits to engage the tissue undercuts, and was stable during use. Mastication, deglutition, articulation and the mid-facial profile of the patient were rehabilitated. After installation of the obturator prosthesis, relining of the prosthesis base was carried out alongside the healing process of the graft, and adjustment of occlusions and high-pressure spots was carried out. No clinical disorders were observed either in the grafted tissue or the obturator prosthesis with a 3-year prognosis. Newly designing a fibular osteocutaneous flap combined with tissue-borne obturator prosthesis is one successful approach to the restoration of oral function, and increases the patient's quality of life after bilateral maxillectomy.

A new method for comprehensive bird's-eye analysis of the surgically excised internal limiting membrane

PURPOSE

To investigate the role of cells and extracellular matrix on the internal limiting membrane (ILM), we demonstrated a new method for a comprehensive bird's-eye analysis of surgically excised ILM.

DESIGN

Laboratory investigation.

METHODS

The ILM of an idiopathic epiretinal membrane was fixed and spread out onto a glass slide, using fine needles under a biomicroscope. The expanded ILM was analyzed by light microscopy, immunohistochemistry, and scanning electron microscopy.

RESULTS

The excised ILM could be unfolded and spread out as a flat sheet onto the glass slide. Immunohistochemistry revealed that most migrating cells were glial cells. Scanning electronmicroscopy revealed that the vitreous surface of the ILM was smooth, in contrast to the rough retinal surface. The ILM showed abundant cellular migration as a continuous stratified cellular sheet.

CONCLUSIONS

This new bird's-eye-view observation of excised ILM enables us to carry out comprehensive analysis of cellular distribution from a temporal and spatial perspective.

Fibrinogen stimulates in vitro angiogenesis by choroidal endothelial cells via autocrine VEGF

BACKGROUND

The purpose of this study is to investigate the effect of fibrinogen on angiogenesis in vitro formed by cultured bovine choroidal endothelial cells (BCECs) and the involvement of vascular endothelial growth factor (VEGF) in this mechanism.

METHODS

For in vitro tube formation assay, BCECs were seeded on collagen gel containing fibrinogen (0-1.5 mg/ml). After 3 days of cultivation, the total length of the tubular structure was measured using Macscope Analyzer. Total RNA and conditioned media were collected after fibrinogen treatment and subjected to Northern and Western blot analyses, respectively. Transcription factor HIF-1alpha was also analyzed by Western blot analysis using cytosolic and nuclear fraction of BCECs. Involvement of VEGF in fibrinogen-dependent in vitro tube formation was evaluated using anti-VEGF neutralizing antibody or VEGF receptor 2-selective inhibitor (SU5416).

RESULTS

Formation of the tubular structure was enhanced 20 to approximately 50 times in fibrinogen-containing gel in a concentration-dependent manner. The treatment of BCECs with fibrinogen resulted in a significant increase in VEGF gene and protein expression. Accumulation of HIF-1alpha protein in the nuclear fraction was also detected after the treatment with fibrinogen. Finally, fibrinogen-induced tube formation was significantly inhibited in the presence of anti-VEGF-neutralizing antibody (52.0% inhibition at the concentration of 1 microg/ml, P<0.05) or SU5416 (54.8% inhibition at the concentration of 3 microM, P<0.05).

CONCLUSIONS

Extravasated fibrinogen might play an important role in the development of choroidal neovascularization associated with age-related macular degeneration, at least in part, through the function of VEGF in an autocrine manner. Transcription factor HIF-1 appears to be involved in fibrinogen-induced VEGF expression.

The Involvement of the Rho-Kinase Pathway and Its Regulation in Cytokine-Induced Collagen Gel Contraction by Hyalocytes

PURPOSE

To investigate the involvement of the Rho-kinase pathway in collagen gel contraction by hyalocytes.

METHODS

An in vitro type I collagen gel contraction assay using cultured bovine hyalocytes was performed to evaluate the effect of PDGF-BB and TGF-beta2. The effect of both cytokines on the phosphorylation of myosin light chain (MLC) was analyzed by Western blot analysis. To confirm the involvement of the Rho-kinase pathway in the collagen gel contraction, the effects of Y27632, a specific Rho-kinase inhibitor were examined. The effect of hydroxyfasudil, another potent Rho-kinase inhibitor, was also evaluated. The expression of alpha-smooth muscle actin (alphaSMA) was analyzed by Western blot analysis to examine the myofibroblast-like transdifferentiation of the hyalocytes.

RESULTS

Maximum collagen gel contraction was observed within 24 hours after treatment with PDGF-BB and much stronger contraction with TGF-beta2, whose effect was time dependent, at least up to 5 days. Although transient and maximum MLC phosphorylation by PDGF-BB was observed at approximately 4 hours after stimulation (180.8%, P <0.01), TGF-beta2-elicited MLC phosphorylation occurred in a time-dependent manner at least up to 24 hours (220.0%, P <0.01) and was maintained up to 5 days. Y27632 demonstrated significant inhibition of collagen gel contraction induced by both cytokines. Hydroxyfasudil dose-dependently (0.03-20.00 microM) prohibited the phosphorylation of MLC, and inhibited collagen gel contraction at a concentration corresponding to that which inhibited MLC phosphorylation. TGF-beta2, but not PDGF-BB, also caused myofibroblast-like transdifferentiation with alphaSMA overexpression, which was downregulated by hydroxyfasudil in part (P <0.01).

CONCLUSIONS

The hyalocytes have a contractile property in the presence of PDGF-BB and TGF-beta2. Whereas PDGF-BB initiates collagen gel contraction by transient activation of the Rho-kinase pathway, sustained activation of the Rho-kinase pathway and myofibroblast-like transdifferentiation appears to be involved in the TGF-beta2-dependent contractile properties of hyalocytes.