Vertebrate eye development is complex and requires early interactions between neuroectoderm and surface ectoderm during embryogenesis. In the African clawed frog, Xenopus laevis, individual eye tissues such as the retina and lens can undergo regeneration. However, it has been reported that removal of either the specified eye field at the neurula stage or the eye during tadpole stage does not induce replacement. Here we describe a model for investigating Xenopus developmental eye repair. We found that tailbud embryos can readily regrow eyes after surgical removal of over 83% of the specified eye and lens tissues. The regrown eye reached a comparable size to the contralateral control by 5 days and overall animal development was normal. It contained the expected complement of eye cell types (including the pigmented epithelium, retina and lens), and is connected to the brain. Our data also demonstrate that apoptosis, an early mechanism that regulates appendage regeneration, is also required for eye regrowth. Treatment with apoptosis inhibitors (M50054 or NS3694) blocked eye regrowth by inhibiting caspase activation. Together, our findings indicate that frog embryos can undergo successful eye repair after considerable tissue loss and reveals a required role for apoptosis in this process. Furthermore, this Xenopus model allows for rapid comparisons of productive eye repair and developmental pathways. It can also facilitate the molecular dissection of signaling mechanisms necessary for initiating repair.

Introduction: Health professionals are expected to understand the relationship between diet and nutrition and overall health. Many relationships between oral health and diet and nutrition are known to contribute to health or disease development. However, few studies to date have evaluated the current dietary habits and behaviors of dental students in the United States. The objective of this study was to complete a longitudinal study of diet and exercise behaviors among dental students during their academic experience at UNLV SDM. Methods: Using and Institutional Review Board (IRB) approved protocol, students in four dental cohorts were asked to take a survey regarding their dietary behaviors, nutrition intake and exercise. A total of n=302/327 students participated, yielding an overall response rate of 92.3%. Self reported age, ethnicity and body mass index (BMI) were also collected. Results: A total of n=302 students completed the survey, for an overall response rate of 92.3% (n=302/327). Males represented 57.9% of respondents, which closely matched the overall percentage of males among the student population overall (56%, P=0.6870), while the percentage of minority respondents in the study sample (58.9%) was slightly higher than in the overall student population (51.6%, P=0.1095). Self-reported height and weight were higher among males (as expected) – although body mass index (BMI) measuring the ratio of height-to-weight was lower for females (24.53 +/- 4.65) than males (26.15 +/- 3.84), P=0.3711. To determine if dietary factors may account for these differences both positive dietary health behaviors (fruit and salad consumption) and negative health behaviors (processed snacks and sugar sweetened beverages) were assessed. Females reported higher consumption of fruits and salads (P=0.0131) and lower consumption of processed foods and snacks (P=0.0114) than males. However, analysis of exercise found that males reported more sessions of physical activity per week than females (P=0.023) and also reported more overall minutes of vigorous exercise (P=0.002). Conclusion:  Although many populations face significant dietary and related behavioral challenges, medical and dental students face particular stress and time-limited challenges that may negatively influence positive health outcomes.  In addition, the perceived clinical relevance of nutrition education may impact future dietary and nutrition-related discussions and provider recommendations. This is among the first dietary studies of self-reported dental student dietary patterns and health behaviors, which demonstrates areas for education and improvement may be needed to increase student wellness, overall health and well-being - as well as targeted points for clinical education that might increase the perceived relevance of dietary and nutrition education.