Identification and Characterization of a Non-muscular Myostatin in the Nile Tilapia

The growth and differentiation factor Myostatin (MSTN, also known as GDF8) negatively regulates skeletal muscle development and growth in vertebrates. Most fish genomes contain two or more mstn genes, which are expressed in muscle and other tissues. Yet, in the genome of Nile tilapia (Oreochromis niloticus), which is one of the world's most important aquaculture fish species, only one mstn gene has previously been identified. Here, we identify a second mstn gene in Nile tilapia. We show that it clusters phylogenetically with other piscine mstn2 genes and that it shares chromosomal synteny with the human and zebrafish orthologs. We further show that mstn2 is not expressed in red or white muscles of Nile tilapia, but rather that its main site of expression is the brain. To determine which physiological functions are correlated with mstn expression, adult Nile tilapia were exposed to various environmental conditions and their effect on mstn1 and mstn2 expression in the brain and muscles was measured using real-time PCR. We found that the centrally- and muscle-expressed mstn genes differ in their responsiveness to diverse challenges, suggesting differential gene- and tissue-specific regulation of their expression. Metabolic and stress marker analyses showed that the altered mstn expression is not regulated by classical stress response. Taken together, our findings expand the understanding of the MSTN system in Nile tilapia and provide evolutionary insight into its function.

Retinal Penetration of Intravitreally Injected Tissue Plasminogen Activator: A Rat Model Study

PURPOSE

To determine whether intravitreal unconjugated tissue plasminogen activator (tPA) (alteplase) can penetrate the intact neural retina and reach the subretinal space in an experimental model.

METHODS

This study was performed in 24 Sprague-Dawley rats aged 12 weeks. Under general anesthesia, the right eye was injected with either 0.75 μg of 3 μL tPA (14 rats; study group) or saline (10 rats, control group) into the vitreous. Animals were euthanized at 3, 24, and 48 h. The eyes were enucleated, and cryosections were prepared for immunofluorescence staining. Goat anti-tPA antibody was used to detect tPA.

RESULTS

In the study group, staining for tPA was detected in the deep retinal layers in all eyes. The staining was deeper and more intense at 3 and 24 h than at 48 h. There was no tPA staining in the retina of eyes injected with saline.

CONCLUSIONS

This experimental study shows that unconjugated tPA administered into the vitreous is capable of penetrating the deep retinal layers and the subretinal space. These findings suggest that further clinical research is warranted on the benefits of intravitreal tPA in the treatment of submacular hemorrhage.

Bevacizumab clearance through the iridocorneal angle following intravitreal injection in a rat model

Antivascular endothelial growth factor (Anti-VEGF) agents have been widely used for a variety of ocular disorders. The etiology of sustained ocular hypertension following intravitreal administration of anti-VEGF agents is yet to be unraveled. Our study investigates and characterizes the presence of intravitreally injected bevacizumab in the aqueous outflow channels of a rat model. Choroidal neovascularization (CNV) was induced by diode laser photocoagulation to the right eye of twelve Brown Norway rats. Bevacizumab (25 mg/ml) was injected intravitreally after 3 days. Immediately after bevacizumab injection, and 3, 6, 24 and 48 h later, animals were euthanized for immunofluorescence staining. Donkey anti-human IgG labeled with Alexa Fluor(®) 488 was used for bevacizumab immunoreactivity detection. Anti-CD31 antibody was used as a marker for Schlemm's canal endothelial cells. Untreated eyes were used as negative controls. The intensity of the immunostaining was analyzed qualitatively. Bevacizumab immunoreactivity was found in the aqueous outflow channels including the trabecular meshwork and Schlemm's canal immediately after injection, and declined incrementally within the following hours. Forty-eight hours after the injection, no bevacizumab staining was detected in the aqueous outflow channel structures. Our manuscript demonstrates the presence of bevacizumab in the trabecular meshwork and Schlemm's canal structures after intravitreal injection in a CNV induced rat model. Bevacizumab molecules passed through the aqueous outflow channels within 48 h after intravitreal bevacizumab injection.

Corneal cut closure using temperature-controlled CO2 laser soldering system

We aimed to evaluate the effectiveness of temperature-controlled laser soldering for repair of large perforated corneas in a porcine model. Eight Yorkshire pigs aged 6 months underwent 6-mm-deep 180° crescent-shaped trephination of the central corneas. Right corneal injuries were repaired by placement of 47 % bovine albumin along the cut followed by CO2 laser soldering (power density 16 W/cm(2)) to a target temperature of 65(°). Left corneal injuries were repaired with 10/0 nylon sutures. The groups were compared for operative time, leakage, and histopathological findings. Mean tissue temperature was 63 ± 4 °C. Mean operative time was 31.57 ± 2.8 min in laser-soldered eyes and 41.38 ± 2.3 min in controls (p < 0.0001, unpaired Student's t test). Compared to controls, the soldered corneas had less neovascularization, complete re-epithelization, and mild stromal inflammation. There was no leakage in either group. Combined CO2 laser and radiometer is effective for the in vivo repair of corneal cuts. These results have important implications for modern corneal surgery. Further studies are needed in the clinical setting.

Protective effect of different ophthalmic viscosurgical devices on corneal endothelium during severe phacoemulsification model in rabbits

BACKGROUND AND OBJECTIVE

To evaluate the protective effect of different ophthalmic viscosurgical devices (OVDs) on corneal endothelial cells against relatively severe phacoemulsification damage in a rabbit model.

MATERIALS AND METHODS

Twenty-four rabbit eyes were randomly assigned to four similar groups: in three groups the aqueous humor was completely replaced by Visiol (TRB CHEMEDICA, München, Germany), Biolon (Bio-Technology General Ltd., Kiryat Malachi, Israel), and Viscoat (Alcon, Puurs, Belgium) and in the control group no OVD was applied. Endothelial cell counts were performed prior to initiating the study. All eyes were exposed to continuous 5 minutes of phacoemulsification. Endothelial cell counts were repeated 4 days postoperatively.

RESULTS

Viscoat showed the highest endothelial cell loss (30%), followed by Biolon (25%), Visiol (22%), and the control group (19%). None of the differences between the groups were found to be statistically significant, although they were within each group (P = .028).

CONCLUSION

None of the tested OVDs demonstrated protective effect on corneal endothelial cells in comparison to the control group. This model was found to be too aggressive for the demonstration of the protective effect of different OVDs even for hard cataract.