Antimicrobial effect of cryopreservation on donor ocular tissue.

PURPOSE: The aim of this study was to assess the antimicrobial effect of cryopreservation on donor globes with a previously positive culture. More specifically, our study aims at determining whether microbial organisms can still be cultured after cryopreservation in previously culture positive donor whole globes. METHODS: This is a prospective quality assurance study of microbiological cultures using donor ocular tissues obtained by the Lions Eye Bank of Manitoba and Northwestern Ontario from January 2009 to January 2010. Enucleated globes were soaked in 2.5% povidone iodide for 5 minutes, rinsed with sterile normal saline, and cultured in chocolate and Sabouraud agar and thioglycolate broth. The whole globes were then preserved in Optimyxin Plus and an antibiotic solution before being cryopreserved for 1 month. Culture-positive whole globes were thawed to room temperature and recultured on the same media to determine the effect of the cryopreservation protocol of our eye bank on bacterial counts. RESULTS: Twenty-seven donor whole globes were included in our study. Upon primary culture, all specimens had positive bacterial growth. The most common isolate on primary culture was coagulase-negative Staphylococcus (62.8%). Upon secondary culture of the thawed cryopreserved whole globes, no bacterial growth was detected on any of the culture media. CONCLUSIONS: Our study demonstrates that harvested donor whole globes with positive microbial cultures became culture negative after secondary culture by the Lions Eye Bank of Manitoba and Northwestern Ontario's cryopreservation protocol. This suggests that ocular tissues treated in this manner may be microbiologically safe and therefore able to be used for transplantation in patients.

Therapeutic targeting of constitutive PARP activation compromises stem cell phenotype and survival of glioblastoma-initiating cells.

Glioblastoma-initiating cells (GICs) are self-renewing tumorigenic sub-populations, contributing to therapeutic resistance via decreased sensitivity to ionizing radiation (IR). GIC survival following IR is attributed to an augmented response to genotoxic stress. We now report that GICs are primed to handle additional stress due to basal activation of single-strand break repair (SSBR), the main DNA damage response pathway activated by reactive oxygen species (ROS), compared with non-GICs. ROS levels were higher in GICs and likely contributed to the oxidative base damage and single-strand DNA breaks found elevated in GICs. To tolerate constitutive DNA damage, GICs exhibited a reliance on the key SSBR mediator, poly-ADP-ribose polymerase (PARP), with decreased viability seen upon small molecule inhibition to PARP. PARP inhibition (PARPi) sensitized GICs to radiation and inhibited growth, self-renewal, and DNA damage repair. In vivo treatment with PARPi and radiotherapy attenuated radiation-induced enrichment of GICs and inhibited the central cancer stem cell phenotype of tumor initiation. These results indicate that elevated PARP activation within GICs permits exploitation of this dependence, potently augmenting therapeutic efficacy of IR against GICs. In addition, our results support further development of clinical trials with PARPi and radiation in glioblastoma.

Canadian ophthalmologists' opinions concerning complementary and alternative medicine (CAM) use in glaucoma.

PURPOSE: Our goal is to investigate the opinion and practice pattern of Canadian ophthalmologists regarding the use of and recommendations for complementary and alternative medicine (CAM) for their glaucoma patients. METHODS: Institutional review board approval for this prospective, cross-sectional survey was obtained from the Research Ethics Board of Sunnybrook Health Sciences Centre. The survey was sent to all ophthalmologists in Canada electronically through the e-mail lists of 4 ophthalmology associations. RESULTS: A total of 241 ophthalmologists representing all provinces in Canada responded to the questionnaire. Twenty-two percent felt that CAM does have a role in glaucoma therapy with specialists being more likely to believe there is a role (P<0.05). Of the total respondents, 26% ask their patients if they use CAM with those in practice for <20 years more likely to encourage use (P<0.05). Of the respondents, 9% recommend CAM and if an ophthalmologist was in practice for <20 years he/she was significantly more likely to recommend CAM (P<0.01). Respondents (62%) in general do not discourage CAM with younger ophthalmologists (younger than 50 y, P<0.02) and ophthalmologists in practice for <20 years (P<0.05) being less likely to discourage CAM use. Respondents (41%) believe that CAM rarely ever affects compliance with ophthalmologists from an urban practice (P<0.01) and academic practice (P<0.05) more likely to deny effect on compliance. Respondents believe that CAM sometimes (46%) results in patient morbidity with ophthalmologists being in practice for <20 years believing that morbidity is less likely (P<0.05). CONCLUSION: A substantial minority of respondents believe that CAM has a role in glaucoma therapy, recommend its use, and ask their patients if they use CAM. Younger doctors are more likely to encourage alternatives; those in practice for <20 years are more likely to ask about alternative medicine use, recommend its use, and believe that morbidity usually does not result from the use of alternative treatments.