Gender-specific gene expression in post-mortem human brain: localization to sex chromosomes.

Gender differences in brain development and in the prevalence of neuropsychiatric disorders such as depression have been reported. Gender differences in human brain might be related to patterns of gene expression. Microarray technology is one useful method for investigation of gene expression in brain. We investigated gene expression, cell types, and regional expression patterns of differentially expressed sex chromosome genes in brain. We profiled gene expression in male and female dorsolateral prefrontal cortex, anterior cingulate cortex, and cerebellum using the Affymetrix oligonucleotide microarray platform. Differentially expressed genes between males and females on the Y chromosome (DBY, SMCY, UTY, RPS4Y, and USP9Y) and X chromosome (XIST) were confirmed using real-time PCR measurements. In situ hybridization confirmed the differential expression of gender-specific genes and neuronal expression of XIST, RPS4Y, SMCY, and UTY in three brain regions examined. The XIST gene, which silences gene expression on regions of the X chromosome, is expressed in a subset of neurons. Since a subset of neurons express gender-specific genes, neural subpopulations may exhibit a subtle sexual dimorphism at the level of differences in gene regulation and function. The distinctive pattern of neuronal expression of XIST, RPS4Y, SMCY, and UTY and other sex chromosome genes in neuronal subpopulations may possibly contribute to gender differences in prevalence noted for some neuropsychiatric disorders. Studies of the protein expression of these sex-chromosome-linked genes in brain tissue are required to address the functional consequences of the observed gene expression differences.     

Evaluating surgical competency with the American Board of Surgery In-Training Examination, skill testing, and intraoperative assessment

BACKGROUND: Evaluation of surgical competency should include assessment of knowledge, technical skill, and judgment. The purpose of this study was to determine the relationship between the American Board of Surgery In-Training Examination (ABSITE), skill testing, and intraoperative assessment. METHODS: Postgraduate year 2 (PGY-2) and postgraduate year 3 (PGY-3) surgery residents (n = 33) were tested by means of (1) the ABSITE, (2) skill testing on a laparoscopic video-trainer, and (3) intra-operative global assessments during laparoscopic cholecystectomy. The Pearson correlation was used to determine the correlation between the ABSITE, skill testing, and intraoperative assessments. For the comparison of PGY-2 and PGY-3 resident performance, Wilcoxon rank sum tests were used. RESULTS: The ABSITE scores did not correlate with skill testing or intraoperative assessments (not significant). Skill testing correlated with the intraoperative composite score and with 4 of 8 operative performance criteria (P<.05). The ABSITE scores and skill testing were not different for PGY-2 and PGY-3 residents (not significant). Intraoperative assessments were better in 5 of 8 criteria and the composite score for PGY-3 versus PGY-2 residents (P<.05), which demonstrated construct validity. CONCLUSIONS: The ABSITE measures knowledge but does not correlate with technical skill or operative performance. Residency programs should use multiple assessment instruments to evaluate competency. There may be a role for both skill testing and intraoperative assessment in the evaluation of surgical competency.