Adeno-associated virus (AAV) vectors are clinically proven gene delivery vehicles that are attracting an increasing amount of attention. Non-genome-containing empty AAV capsids are by-products during AAV production that have been reported to potentially impact AAV product safety and efficacy. Therefore, the presence and amount of empty AAV capsids need to be characterized during process development. Multiple methods have been reported to characterize empty AAV capsid levels, including transmission electron microscopy (TEM), analytical ultracentrifugation (AUC), charge detection mass spectrometry (CDMS), UV spectrophotometry, and measuring capsid and genome copies by ELISA and qPCR. However, these methods may lack adequate accuracy and precision or be challenging to transfer to a quality control (QC) lab due to the difficulty of implementation. In this study, we used AAV serotype 6.2 (AAV6.2) as an example to show the development of a QC-friendly anion exchange chromatography (AEX) assay for the determination of empty and full capsid percentages. The reported assay requires several microliters of material with a minimum titer of 5 × 1011 vg/mL, and it can detect the presence of as low as 2.9% empty capsids in AAV6.2 samples. Additionally, the method is easy to deploy, can be automated, and has been successfully implemented to support testing of various in-process and release samples.
The combination of UGPAs and MCAT total scores performs well as a predictor of UP. Both UGPAs and MCAT total scores are strong predictors of academic performance in medical school through graduation, not just the first two years. Further, these relationships generalize across medical schools.
The Medical College Admission Test (MCAT) is a standardized examination that assesses fundamental knowledge of scientific concepts, critical reasoning ability, and written communication skills. Medical school admission officers use MCAT scores, along with other measures of academic preparation and personal attributes, to select the applicants they consider the most likely to succeed in medical school. In 2008-2011, the committee charged with conducting a comprehensive review of the MCAT exam examined four issues: (1) whether racial and ethnic groups differ in mean MCAT scores, (2) whether any score differences are due to test bias, (3) how group differences may be explained, and (4) whether the MCAT exam is a barrier to medical school admission for black or Latino applicants. This analysis showed that black and Latino examinees' mean MCAT scores are lower than white examinees', mirroring differences on other standardized admission tests and in the average undergraduate grades of medical school applicants. However, there was no evidence that the MCAT exam is biased against black and Latino applicants as determined by their subsequent performance on selected medical school performance indicators. Among other factors which could contribute to mean differences in MCAT performance, whites, blacks, and Latinos interested in medicine differ with respect to parents' education and income. Admission data indicate that admission committees accept majority and minority applicants at similar rates, which suggests that medical students are selected on the basis of a combination of attributes and competencies rather than on MCAT scores alone.
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