A Novel High-Content Flow Cytometric Method for Assessing the Viability and Damage of Rat Retinal Ganglion Cells

PURPOSE: The aim of the study was to develop a high-content flow cytometric method for assessing the viability and damage of small, medium, and large retinal ganglion cells (RGCs) in N-methyl-D-aspartic acid (NMDA)-injury model. METHODS/RESULTS: Retinal toxicity was induced in rats by intravitreal injection of NMDA and RGCs were retrogradely labeled with Fluoro-Gold (FG). Seven days post-NMDA injection, flatmount and flow cytometric methods were used to evaluate RGCs. In addition, the RGC area diameter (D((a))) obtained from retinal flatmount imaging were plotted versus apparent volume diameter (D((v))) obtained from flow cytometry for the same cumulative cell number (sequentially from small to large RGCs) percentile (Q) to establish their relationship for accurately determining RGC sizes. Good correlation (r = 0.9718) was found between D((a)) and apparent D((v)). Both flatmount and flow cytometric analyses of RGCs showed that 40 mM NMDA significantly reduced the numbers of small and medium RGCs but not large RGCs. Additionally, flow cytometry showed that the geometric means of FG and thy-1 intensities in three types of RGCs decreased to 90.96±2.24% (P<0.05) and 91.78±1.89% (P>0.05) for small, 69.62±2.11% (P<0.01) and 69.07±2.98% (P<0.01) for medium, and 69.68±6.48% (P<0.05) and 69.91±6.23% (P<0.05) for large as compared with the normal RGCs. CONCLUSION: The established flow cytometric method provides high-content analysis for differential evaluation of RGC number and status and should be useful for the evaluation of various models of optic nerve injury and the effects of potential neuroprotective agents

Does the oxytocin receptor polymorphism (rs2254298) confer 'vulnerability' for psychopathology or 'differential susceptibility'? insights from evolution

The diathesis-stress model of psychiatric conditions has recently been challenged by the view that it might be more accurate to speak of 'differential susceptibility' or 'plasticity' genes, rather than one-sidedly focusing on individual vulnerability. That is, the same allelic variation that predisposes to a psychiatric disorder if associated with (developmentally early) environmental adversity may lead to a better-than-average functional outcome in the same domain under thriving (or favourable) environmental conditions. Studies of polymorphic variations of the serotonin transporter gene, the monoamino-oxidase-inhibitor A coding gene or the dopamine D4 receptor gene indicate that the early environment plays a crucial role in the development of favourable versus unfavourable outcomes. Current evidence is limited, however, to establishing a link between genetic variation and behavioural phenotypes. In contrast, little is known about how plasticity may be expressed at the neuroanatomical level as a 'hard-wired' correlate of observable behaviour. The present review article seeks to further strengthen the argument in favour of the differential susceptibility theory by incorporating findings from behavioural and neuroanatomical studies in relation to genetic variation of the oxytocin receptor gene. It is suggested that polymorphic variation at the oxytocin receptor gene (rs2254298) is associated with sociability, amygdala volume and differential risk for psychiatric conditions including autism, depression and anxiety disorder, depending on the quality of early environmental experiences. Seeing genetic variation at the core of developmental plasticity can explain, in contrast to the diathesis-stress perspective, why evolution by natural selection has maintained such 'risk' alleles in the gene pool of a population

Mandatory continuing education in physical therapy: Survey of physical therapists in states with and states without a mandate

Background and Purpose. Although formal continuing education (CE) in physical therapy is one part of professional development, its value for renewing licensure is not shared by all states. The purpose of this study was to explore the differences in how physical therapists pursue formal continuing education on the basis of state mandate, sex, years of experience, practice specialty, American Physical Therapy Association membership, motivation, and perception of the benefits of CE. Subjects and Methods. A survey questionnaire was sent to 3,000 physical therapists in 7 states-1,500 to physical therapists in states with mandatory CE and 1,500 to physical therapists in states without a requirement. A total of 1,145 usable survey questionnaires were returned, for a response rate of 38.2%. Results. Physical therapists in states with mandatory CE averaged 33.8 hours of CE per year, whereas physical therapists in states without a mandate averaged 28.3 hours per year; 5.9% of therapists in states without a mandate reported taking no CE at all, and 10.8% reported taking 2 or fewer hours of CE within the preceding 5 years. No statistically significant relationships were observed between the amount of CE taken and years of experience, sex, or practice specialty. Therapists who reported membership in the American Physical Therapy Association participated in 7.2 more hours of CE per year than therapists who did not report membership. Significant motivational variables that respondents noted for taking CE were state mandate, increased clinical competence, and certification. Therapists overwhelmingly (96.2%) believed that CE had a beneficial effect on their clinical practice. Discussion and Conclusion. Results from this study suggest that mandatory CE does have a significant association with the number of formal CE hours taken by physical therapists