Poly(ADP-ribose) polymerase, a major determinant of early cell response to ionizing radiation

PURPOSE: To determine whether DNA-dependent protein kinase (DNA-PK) and poly(ADP-ribose) polymerase (PARP-1) are involved in eliciting the rapid fluctuations of radiosensitivity that have been observed when cells are exposed to short pulses of ionizing radiation. MATERIALS AND METHODS: The effect of DNA-PK and PARP-1 inhibitors on the survival of cells to split-dose irradiation was investigated using Chinese hamster V79 fibroblasts and human carcinoma SQ-20B cells. The responses of PARP-1 proficient and PARP-1 knockout mouse 3T3 fibroblasts were compared in a similar split-dose assay. RESULTS: Inactivation of DNA-PK by wortmannin potentiated radiation-induced cell kill but it did not alter the oscillatory, W-shaped pattern of early radiation response. In contrast, oscillatory radiation response was abolished by 3-aminobenzamide, a reversible inhibitor of enzymes containing a PARP catalytic domain. The oscillatory response was also lacking in PARP-1 knockout mouse 3T3 fibroblasts. CONCLUSION: The results show that PARP-1 plays a key role in the earliest steps of cell response to ionizing radiation with clonogenic ability or growth as endpoint. It is hypothesized that rapid poly(ADP-ribosylation) of target proteins, or recruitment of repair proteins by activated PARP-1 at the sites of DNA damage, bring about rapid chromatin remodelling that may affect the incidence of chromosomal damage upon re-irradiation

Supplementary Material for: Patient Experience Survey Of Anti-VEGF Treatment for Neovascular Age-Related Macular Degeneration and Diabetic Macular Edema

Introduction: Understanding patient perspectives of treatment may improve adherence and outcomes. This study explored real-world patient experiences with anti-vascular endothelial growth factor (anti-VEGF) treatment for diabetic macular edema (DME) and neovascular age-related macular degeneration (nAMD). Methods: This multinational, non-interventional, quantitative, cross-sectional, observational survey assessed treatment barriers/burden, patient-reported visual functioning, and treatment satisfaction in DME and nAMD patients in the United States, United Kingdom, Canada, France, Italy, and Spain. Treatment patterns and visual outcomes were extracted from medical charts. Regression models evaluated relationships between adherence, total missed visits, number of anti-VEGF injections and clinical and patient-reported outcomes for visual functioning. Association between treatment satisfaction and aspects of burden were assessed. Results: The survey was completed by 183 DME and 391 nAMD patients. Patients had moderately high vision-related functioning (25-item National Eye Institute Visual Functioning Questionnaire score: mean=74.8) and were satisfied with their current treatment (mean total score: Macular Disease Treatment Satisfaction Questionnaire=59.2; Retinopathy Treatment Satisfaction Questionnaire=61.3). Treatment satisfaction scores were worse with higher time-related impacts of treatment (nAMD/DME), higher impacts on finances and daily life (nAMD), negative impact on employment and lower expectations for treatment effectiveness (DME). Most patients reported ≥1 barrier (66.1% DME, 49.2% nAMD patients) related to treatment (35.0%), clinic (32.6%), and COVID-19 (21.1%). Moreover, 44.9% of patients reported some impairment in activities of daily living. Work absenteeism was observed among >60% of working patients. Nearly one-quarter (24.2%) of patients needed ≥1 day to recover from intravitreal injections; most reported ≥30 minutes of travel time (73.7%) and clinic wait time (54.2%). In unadjusted univariable analyses, treatment adherence (vs non adherence) was related to higher most recent visual acuity (β = 8.98 letters; CI, 1.34–16.62) and lower odds of visual acuity below driving vision (≤ 69 letters) (OR = 0.50; CI, 0.25–1.00) . Conclusion: More durable treatments with reduced frequency of injections/visits may reduce treatment burden and improve patient satisfaction, which may enhance adherence and visual outcomes