Corneal thickness and intraocular pressure in edematous corneas before and after Descemet stripping with automated endothelial keratoplasty.

PURPOSE: It is important to accurately measure intraocular pressure (IOP) in eyes with corneal endothelial dysfunction both before and after Descemet stripping with automated endothelial keratoplasty (DSAEK). Glaucoma is a common comorbidity in this population, and IOP elevation can worsen corneal edema. Additionally, preexisting glaucoma and steroid-responsive ocular hypertension are significant risk factors for graft rejection after DSAEK. Accurate tonometry is limited by variations in central corneal thickness (CCT) and corneal hydration that may affect corneal biomechanical properties. We analyzed CCT and IOP in eyes before and after DSAEK to determine whether changes in corneal biomechanics because of edema, grafted tissue, and subsequent stromal deturgescence affect IOP measurement. METHODS: A retrospective chart review was performed on 32 eyes from 31 patients with corneal edema secondary to Fuchs endothelial dystrophy, bullous keratopathy, or prior graft failure, or rejection that received uncomplicated DSAEK with no evidence of persistent corneal edema or steroid-induced ocular hypertension. IOP was measured by Tono-Pen XL, and CCT was measured by ultrasound pachymetry before and approximately 3 months after surgery. We used paired t tests to evaluate changes in CCT and IOP after DSAEK and linear regression to determine the relationship between CCT and IOP before and after surgery. RESULTS: CCT significantly decreased from 703 ± 82 to 650 ± 52 µm after DSAEK (P = 0.0026), but there was no significant change in measured IOP (16.7 ± 3.4 mm Hg preoperatively and 16.3 ± 4.1 mm Hg postoperatively; P = 0.61). There was no significant relationship between CCT and IOP before (slope = 0.10 ± 0.07 mm Hg/10 µm; r = 0.062; P = 0.17) or after (slope = 0.21 ± 0.14 mm Hg/10 µm; r = 0.072; P = 0.14) DSAEK. CONCLUSION: CCT is significantly reduced by DSAEK but remains well above the normal range. IOP remains near the preoperative level 3 months after DSAEK. Furthermore, no correction is required for Tono-Pen measurements of IOP in corneas thickened by edema secondary to endothelial dysfunction or by DSAEK.

Intracameral dexamethasone reduces inflammation on the first postoperative day after cataract surgery in eyes with and without glaucoma.

PURPOSE: To evaluate whether dexamethasone injected intracamerally at the conclusion of surgery can safely and effectively reduce postoperative inflammation and improve surgical outcomes in eyes with and without glaucoma. METHODS: Retrospective chart review of 176 consecutive eyes from 146 patients receiving uncomplicated phacoemulsification (PE) (n = 118 total, 82 with glaucoma), glaucoma drainage device (GDD) (n = 35), combined PE/GDD (n = 11) and combined PE/endoscopic cyclophotocoagulation (n = 12). Ninety-one eyes from 76 patients were injected with 0.4 mg dexamethasone intracamerally at the conclusion of surgery. All eyes received standard postoperative prednisolone and ketorolac eyedrops. Outcomes were measured for four to eight weeks by subjective complaints, visual acuity (VA), slit-lamp biomicroscopy, intraocular pressure (IOP) and postoperative complications. RESULTS: Dexamethasone significantly reduced the odds of having an increased anterior chamber (AC) cell score after PE (p = 0.0013). Mean AC cell score +/- SD in nonglaucomatous eyes was 1.3 +/- 0.8 in control and 0.8 +/- 0.7 with dexamethasone; scores in glaucomatous eyes were 1.3 +/- 0.7 in control and 0.9 +/- 0.8 with dexamethasone. Treated nonglaucomatous eyes had significantly fewer subjective complaints after PE (22.2% vs 64.7% in control; p = 0.0083). Dexamethasone had no significant effects on VA, corneal changes, IOP one day and one month after surgery, or long-term complications. CONCLUSIONS: Intracameral dexamethasone given at the end of cataract surgery significantly reduces postoperative AC cells in eyes with and without glaucoma, and improves subjective reports of recovery in nonglaucomatous eyes. There were no statistically significant risks of IOP elevation or other complications in glaucomatous eyes.

Enteroendocrine cells express functional Toll-like receptors.

Intestinal epithelial cells (IECs) provide a physical and immunological barrier against enteric microbial flora. Toll-like receptors (TLRs), through interactions with conserved microbial patterns, activate inflammatory gene expression in cells of the innate immune system. Previous studies of the expression and function of TLRs in IECs have reported varying results. Therefore, TLR expression was characterized in human and murine intestinal sections, and TLR function was tested in an IEC line. TLR1, TLR2, and TLR4 are coexpressed on a subpopulation of human and murine IECs that reside predominantly in the intestinal crypt and belong to the enteroendocrine lineage. An enteroendocrine cell (EEC) line demonstrated a similar expression pattern of TLRs as primary cells. The murine EEC line STC-1 was activated with specific TLR ligands: LPS or synthetic bacterial lipoprotein. In STC-1 cells stimulated with bacterial ligands, NF-kappaB and MAPK activation was demonstrated. Furthermore, the expression of TNF and macrophage inhibitory protein-2 were induced. Additionally, bacterial ligands induced the expression of the anti-inflammatory gene transforming growth factor-beta. LPS triggered a calcium flux in STC-1 cells, resulting in a rapid increase in CCK secretion. Finally, conditioned media from STC-1 cells inhibited the production of nitric oxide and IL-12 p40 by activated macrophages. In conclusion, human and murine IECs that express TLRs belong to the enteroendocrine lineage. Using a murine EEC model, a broad range of functional effects of TLR activation was demonstrated. This study suggests a potential role for EECs in innate immune responses.

Mitochondrial trafficking and morphology in healthy and injured neurons.

Mitochondria are the primary generators of ATP and are important regulators of intracellular calcium homeostasis. These organelles are dynamically transported along lengthy neuronal processes, presumably for appropriate distribution to cellular regions of high metabolic demand and elevated intracellular calcium, such as synapses. The removal of damaged mitochondria that produce harmful reactive oxygen species and promote apoptosis is also thought to be mediated by transport of mitochondria to autophagosomes. Mitochondrial trafficking is therefore important for maintaining neuronal and mitochondrial health while cessation of movement may lead to neuronal and mitochondrial dysfunction. Mitochondrial morphology is also dynamic and is remodeled during neuronal injury and disease. Recent studies reveal different manifestations and mechanisms of impaired mitochondrial movement and altered morphology in injured neurons. These are likely to cause varied courses toward neuronal degeneration and death. The goal of this review is to provide an appreciation of the full range of mitochondrial function, morphology and trafficking, and the critical role these parameters play in neuronal physiology and pathophysiology.

Mitochondrial trafficking to synapses in cultured primary cortical neurons.

Functional synapses require mitochondria to supply ATP and regulate local [Ca2+]i for neurotransmission. Mitochondria are thought to be transported to specific cellular regions of increased need such as synapses. However, little is known about how this occurs, including the spatiotemporal distribution of mitochondria relative to presynaptic and postsynaptic sites, whether mitochondria are dynamically recruited to synapses, and how synaptic activity affects these trafficking patterns. We used primary cortical neurons in culture that form synaptic connections and show spontaneous synaptic activity under normal conditions. Neurons were cotransfected with a mitochondrially targeted cyan fluorescent protein and an enhanced yellow fluorescent protein-tagged synaptophysin or postsynaptic density-95 plasmid to label presynaptic or postsynaptic structures, respectively. Fluorescence microscopy revealed longer dendritic mitochondria that occupied a greater fraction of neuronal process length than axonal mitochondria. Mitochondria were significantly more likely to be localized at synaptic sites. Although this localization was unchanged by inhibition of synaptic activity by tetrodotoxin, it increased in dendritic synapses and decreased in axonal synapses during overactivity by veratridine. Mitochondrial movement and recruitment to synapses also differed between axons and dendrites under basal conditions and when synaptic activity was altered. Additionally, we show that movement of dendritic mitochondria can be selectively impaired by glutamate and zinc. We conclude that mitochondrial trafficking to synapses is dynamic in neurons and is modulated by changes in synaptic activity. Furthermore, mitochondrial morphology and distribution may be optimized differentially to best serve the synaptic distributions in axons and dendrites. Last, selective cessation of mitochondrial movement in dendrites suggests early postsynaptic dysfunction in neuronal injury and degeneration.

Mutant huntingtin aggregates impair mitochondrial movement and trafficking in cortical neurons.

Huntington's disease (HD) is a neurodegenerative disorder caused by a polyglutamine repeat in the huntingtin gene (Htt). Mitochondrial defects and protein aggregates are characteristic of affected neurons. Recent studies suggest that these aggregates impair cellular transport mechanisms by interacting with cytoskeletal components and molecular motors. Here, we investigated whether mutant Htt alters mitochondrial trafficking and morphology in primary cortical neurons. We demonstrate that full-length mutant Htt was more effective than N-terminal mutant Htt in blocking mitochondrial movement, an effect that correlated with its heightened expression in the cytosolic compartment. Aggregates impaired the passage of mitochondria along neuronal processes, causing mitochondria to accumulate adjacent to aggregates and become immobilized. Furthermore, mitochondrial trafficking was reduced specifically at sites of aggregates while remaining unaltered in regions lacking aggregates. We conclude that in cortical neurons, an early event in HD pathophysiology is the aberrant mobility and trafficking of mitochondria caused by cytosolic Htt aggregates.