Biochemical properties and aggregation propensity of transforming growth factor-induced protein (TGFBIp) and the amyloid forming mutants.

TGFBI-associated corneal dystrophies are characterized by accumulation of insoluble deposits of the mutant protein transforming growth factor ß-induced protein (TGFBIp) in the cornea. Depending on the nature of mutation, the lesions appear as granular (non-amyloid) or lattice lines (amyloid) in the Bowman's layer or in the stroma. This review article emphasizes the structural biology aspects of TGFBIp. We discuss the tinctorial properties and ultrastructure of deposits observed in granular and lattice corneal dystrophic mutants with amyloid and non-amyloid forms of other human protein deposition diseases and review the biochemical and putative functional role of the protein. Using bioinformatics tools, we identify intrinsic aggregation propensity and discuss the possible protective role of gatekeepers close to the "aggregation-prone" regions of native TGFBIp. We describe the relative aggregation rates of lattice corneal dystrophy (LCD) and granular corneal dystrophy (GCD2) mutants using the three-parameter model, which is based on intrinsic properties of polypeptide chains. The predictive power of this model is compared with two other algorithms. We conclude that the model is able to predict the aggregation rate of mutants which do not alter overall net charge of the protein. The need to understand the mechanism of corneal dystrophies from the structural biology viewpoint is emphasized.

Clinical and genetic aspects of the TGFBI-associated corneal dystrophies.

Corneal dystrophies are a group of inherited disorders localized to various layers of the cornea that affect corneal transparency and visual acuity. The deposition of insoluble protein materials in the form of extracellular deposits or intracellular cysts is pathognomic. Mutations in TGFBI are responsible for superficial and stromal corneal dystrophies. The gene product, transforming growth factor ß induced protein (TGFBIp) accumulates as insoluble deposits in various forms. The severity, clinicopathogenic variations, age of the onset, and location of the deposits depend on the type of amino acid alterations in the protein. Until 2006, 38 different pathogenic mutants were reported for the TGFBI-associated corneal dystrophies. This number has increased to 63 mutants, reported in more than 30 countries. There is no effective treatment to prevent, halt, or reverse the deposition of TGFBIp. This review presents a complete mutation update, classification of phenotypes, comprehensive reported incidents of various mutations, and current treatment options and their shortcomings. Future research directions and possible approaches to inhibiting disease progression are discussed.

Descemet stripping automated endothelial keratoplasty after failed penetrating keratoplasty: survival, rejection risk, and visual outcome.

IMPORTANCE: Descemet stripping automated endothelial keratoplasty (DSAEK) for isolated endothelial dysfunction has become the preferred surgical option for many corneal surgeons. However, there are limited large-scale reports on DSAEK survival and clinical variables affecting the risk of rejection and failure after failed penetrating keratoplasty (PK). OBJECTIVE: To report the survival, risk factors for graft rejection and failure, and visual outcome of DSAEK after failed PK. DESIGN, SETTING, AND PARTICIPANTS: A multicenter retrospective interventional case series included patients recruited from 6 tertiary referral surgical centers: 3 in the United States, 2 in Europe, and 1 in Asia. A total of 246 consecutive eyes (246 patients) that underwent DSAEK after failed PK, with a minimum follow-up period of 1 month, was included. Data comprising demographic details, preoperative and postoperative risk factors, time to rejection, time to failure, and corrected distance visual acuity were collected. MAIN OUTCOMES AND MEASURES: Cumulative probability of graft survival, hazard ratio estimates for survival, and corrected distance visual acuity were determined. RESULTS: The mean (SD) recipient age was 63.2 (16.6) years and the median follow-up period was 17 months (interquartile range, 6-30 months). One-third of the grafts (n = 82) had follow-up data for more than 2 years; 18.3% had more than 1 failed PK before DSAEK. In total, 19.1% (47 of 246) of DSAEK grafts failed. The cumulative probability of DSAEK survival after a failed PK was 0.89 (95% CI, 0.84-0.92), 0.74 (95% CI, 0.64-0.81), and 0.47 (95% CI, 0.29-0.61) at 1 year, 3 years, and 5 years, respectively. Based on multivariate analysis, significant preoperative risk factors for failure were young recipient age (hazard ratio [HR], 5.18 [95% CI, 1.57-17.18]), previous tube filtration surgery (HR, 5.23 [95% CI, 1.47-7.33]), and rejection episodes before PK failure (HR, 3.28 [95% CI, 1.47-7.33]); single-surgeon centers had a protective effect. Any rejection episode prior to PK failure was a significant predictor of post-DSAEK rejection, which in turn was a significant predictor of DSAEK failure. After a median follow-up of 17 months, 33.3% of the grafts achieved 0.3 or greater logMAR (20/40) corrected distance visual acuity. CONCLUSIONS AND RELEVANCE: Descemet stripping automated endothelial keratoplasty after failed PK combines greater wound stability and reduced suture-related complications, with visual outcomes and graft survival rates comparable to those of a second PK.

Randomized, controlled trial of a sustained delivery formulation of 5-fluorouracil for the treatment of failing blebs.

PURPOSE: To determine the efficacy of a subconjunctival injection of hyaluronic acid (HA) with 5-fluorouracil (5FU) formulation as an adjunct in reviving bleb function by needling. DESIGN: Prospective, randomized, controlled trial. PARTICIPANTS: Fifty patients with previous trabeculectomy and scheduled by the managing physician for a needling intervention. METHODS: One eye of each patient was randomized to receive needling with HA-5FU mixture or needling with subconjunctival injection of 5FU solution alone. MAIN OUTCOME MEASURES: The primary outcome was the percentage of subjects with an intraocular pressure (IOP) <15 mmHg without any medications at 3 months. Secondary outcomes included the need for additional needling procedures and changes in bleb morphology. RESULTS: Forty-nine subjects (25 in the HA-5FU group and 24 in the 5FU group) completed 3 months of follow-up. At baseline, there was no significant difference between the groups in terms of demographic features, subtype of glaucoma, vertical cup-to-disc ratio, or visual field indices. The mean number of glaucoma medications at baseline was higher in the 5FU group (0.8±1.1 [mean ± standard deviation] vs. 0.2±0.6, P = 0.04). An IOP <15 mmHg without medications was reached in 48.0% of subjects in the HA-5FU group and in 33.3% of subjects in the 5FU group (P = 0.2). At 3 months, both groups demonstrated a significant decrease in IOP from baseline (HA-5FU: decrease of 5.9 mmHg [95% confidence interval, 3.4-8.4]; 5FU: decrease of 6.0 mmHg [95% confidence interval, 3.2-8.2]; P<0.001 for both). Intergroup comparisons for IOP change from baseline was not significant (P = 0.9). However, repeat needling was required more frequently in the 5FU group compared with the HA-5FU group (50.0% vs. 12.0%; P = 0.004). There were no significant differences in the number of reported adverse events, bleb vascularity, or morphology between the 2 groups. CONCLUSIONS: Subconjunctival injection of HA-5FU to revive bleb function after bleb needling is as effective as 5FU solution. Fewer repeat needlings were required after treatment with HA-5FU, suggesting that the use of a combined formulation of HA-5FU may improve the overall outcomes of bleb needlings.

A novel mutation in transforming growth factor-beta induced protein (TGFßIp) reveals secondary structure perturbation in lattice corneal dystrophy.

BACKGROUND: To describe mutations in the transforming growth factor-beta induced (TGFBI) gene in Asian patients with Bowman's membrane as well as stromal corneal dystrophies, and to elucidate their structural implications, using model peptides. METHODS: Twenty-two unrelated Asian families were examined clinically including visual acuity testing and ocular examination with slit lamp biomicroscopy. Genomic DNA was extracted and the 17 exons of the TGFBI gene were amplified by PCR and sequenced bi-directionally. Biophysical techniques were used to characterise the wild type and mutant model peptides. RESULTS: Molecular genetic analysis identified a variety of mutations in our patient series including a novel heterozygous C to A transversion mutation in exon 14 (c.1859C→A), resulting in a substitution of a highly conserved alanine residue by aspartic acid (p.A620D). Clinical presentation in the patient with the p.A620D included subepithelial scarring in addition to the linear branching opacities usually seen with lattice dystrophy. Using model peptides, we showed that A620D mutant peptide alters the secondary structure and conformational stability, and increased amyloid formation. CONCLUSION: A novel mutation (A620D) in transforming growth factor-beta induced protein (TGFßIp) is described, expanding the repertoire of mutations in this protein. Using model peptides, we demonstrated that A→D substitution leads to perturbation of the secondary structure that may be responsible for the amyloid formation in lattice corneal dystrophy.

Retinal vasculopathy in Fanconi anemia.

The authors present a case of Fanconi anemia with bilateral rapid onset retinal neovascularization and vitreous hemorrhage. The patient developed branch retinal vein occlusion in the left eye complicated by vitreous hemorrhage and was treated conservatively with intravitreal hyaluronidase injection. He declined vitrectomy and his visual acuity deteriorated to no perception of light. On follow-up, the right eye was noted to have clinical and angiographic evidence of sheathed vessels, an isolated large frond of neovascularization associated with areas of capillary nonperfusion. Panretinal photocoagulation and vitrectomy were performed with stabilization of vasculopathy and visual acuity. This case illustrates rapid onset peripheral occlusive vasculopathy with an atypical large isolated frond of neovascularization in a patient with Fanconi anemia resulting in blindness in one eye. Patients with Fanconi anemia would benefit from close and regular ophthalmological review.

Asthma knowledge among adult asthmatic outpatients in a tertiary care hospital.

We conducted a prospective, cross sectional survey on 94 asthmatic subjects using an interviewer-administered questionnaire to audit the level of knowledge of adult asthmatic outpatients at a tertiary care hospital, in order to determine the sources of asthma information and variables associated with poor asthma knowledge. Of the 94 subjects, 39.4% were ignorant of the inflammatory nature of asthma while 56.4% did not understand the role of prednisolone in acute exacerbation of asthma. Only 17.0% reported having a written action plan. Lower educational level and older age were significantly associated with lower asthma knowledge scores. The doctor was the main source of asthma information. Asthma knowledge scores were significantly higher among those who named the doctor, pamphlets, newspapers, internet and books as a source of asthma information. Our study demonstrates that many asthmatics have poor understanding of some aspects of their disease and have no written asthma action plan.