Recent Progress in Using Biomaterials as Vitreous Substitutes.

Vitreous substitutes are crucial adjuncts during vitreo-retinal surgery for retinal diseases such as complicated retinal detachment, macular holes, complications of diabetic retinopathy, and ocular trauma involving posterior segment. In retinal detachment surgery, an internal tamponade agent is required to provide internal pressure for reattachment of the detached neurosensory retina. Current available options serve only as a temporary surgical adduct or short-term solution and are associated with inherent problems. Despite many years of intensive research, an ideal vitreous substitute remains elusive. Indeed, the development of an ideal vitreous substitute requires the concerted efforts of synthetic chemists and biomaterial engineers, as well as ophthalmic surgeons. In this review, we propose that polymeric hydrogels present the future of artificial vitreous substitutes due to its high water composition, optical transparency, and rheological properties that closely mimic the natural vitreous. In particular, thermosensitive smart hydrogels, with reversible sol to gel change, have emerged as the material class with the most potential to succeed as ideal vitreous substitutes, facilitating easy implementation during surgery. Importantly, these smart hydrogels also display potential as efficacious drug delivery systems.

Clinical and molecular characteristics of East Asian patients with von Hippel-Lindau syndrome.

BACKGROUND: Von Hippel-Lindau (VHL) syndrome is a dominantly inherited multisystem cancer syndrome caused by a heterozygous mutation in the VHL tumor suppressor gene. Previous studies suggested that similar populations of Caucasian and Japanese patients have similar genotype or phenotype characteristics. In this comprehensive study of East Asian patients, we investigated the genetic and clinical characteristics of patients with VHL syndrome. METHODS: To create a registry of clinical characteristics and mutations reported in East Asian patients with VHL syndrome, we conducted a comprehensive review of English language and non-English language articles identified through a literature search. Publications in Japanese or Chinese language were read by native speakers of the language, who then performed the data extraction. RESULTS: Of 237 East Asian patients with VHL syndrome, 154 unique kindreds were identified for analysis. Analyzed by kindred, missense mutations were the most common (40.9%, 63/154), followed by large/complete deletions (32.5%, 50/154) and nonsense mutations (11.7%, 18/154). Compared with a previously reported study of both East Asian and non-East Asian patients, we found several key differences. First, missense and frameshift mutations in the VHL gene occurred less commonly in our population of East Asian patients (40.9% vs. 52.0%; P = 0.012 and 8.4% vs. 13.0%; P < 0.001, respectively). Second, large/complete deletions were more common in our population of East Asian patients (32.5% vs. 10.5%; P < 0.001). Third, phenotypically, we observed that, in our population of East Asian patients with VHL syndrome, the incidence of retinal capillary hemangioblastoma was lower, whereas the incidence of renal cell carcinoma was higher. CONCLUSIONS: Evidence suggests that the genotypic and phenotypic characteristics of East Asian patients with VHL syndrome differ from other populations. This should be considered when making screening recommendations for VHL syndrome in Asia.

Assessment of the American Joint Committee on Cancer 7th edition staging for localised prostate cancer in Asia treated with external beam radiotherapy.

INTRODUCTION: Most international clinical practice guidelines for prostate cancer (PCa) are driven by data derived in a Western setting. However, tumour biology and clinical disease progression are likely to differ in the Asian population. We compare the performance of the revised American Joint Committee on Cancer (AJCC) prognostic groups with the commonly used D'Amico Risk Classification and conventional predictors for PCa, in a large cohort of Asian patients. MATERIALS AND METHODS: We retrospectively reviewed data for 404 consecutive Singaporean patients receiving definitive radiotherapy at our centre between December 1996 and October 2006. The primary outcome was biochemical relapse-free survival (BRFS), defined using the Phoenix definition. The secondary outcome was overall survival (OS). Prognostic risk groups were defined using AJCC 7th edition (AJCC7) and 6th edition (AJCC6). Univariate analysis (UVA) and multivariate analysis (MVA) were performed for the following putative risk factors: age, Gleason score, prognostic grouping, tumour classification, radiation delivery technique, radiotherapy dose, hormonal therapy and initial PSA value. RESULTS: For the cohort, median age was 69 years. Median follow-up was 66.3 months. Five-year BRFS rate was 84.3% with 71 biochemical relapses and 5-year OS rate was 89.1% with 54 deaths. The concordance-indices for BRFS prediction were 0.588, 0.550 and 0.567 for AJCC7, AJCC6 and D'Amico respectively. Initial PSA, T-stage and AJCC7 were prognostic for BRFS on UVA. Comparison of AJCC7 vs. D'Amico showed no statistical additional value of either classification system although D'Amico was superior when compared to AJCC6 in predicting BRFS. T-stage ≥3 and D'Amico were significant prognostic factors for BRFS on MVA. CONCLUSION: In our local, predominantly Chinese population, neither AJCC6 nor AJCC7 demonstrated a high predictive accuracy for BRFS although AJCC7 has a slightly better predictive ability than AJCC6.