Multivariate Discriminant Function Analyses of the Mandible in American Caucasoid and American Negroid Populations

The purpose of this thesis is to develop a statistical method whereby the race and sex of an unknown individual may be ascertained from measurements taken from the mandible alone. Twenty-five such measurements were obtained from 160 mandibles representing, equally, American male and female Negro and Caucasian individuals. The skeletal collection used was the Terry collection at the Smithsonian Institution in Washington, D.C. The data obtained were analyzed by nine separate discriminate functions representing various aspects of the mandible, including one which discriminated the samples by race only. To test the significance and reliability of using such a procedure for forensic purposes, 13 test specimens were obtained from the University of Tennessee Anthropology Department forensic cases. These were subjected to discriminant function analysis which correctly identified anywhere from 38.5% to 76.9% of them (as opposed to a classification range of 37.5% to 97.5% in the reference samples themselves). Further, using the discriminant function which classified only race, a test was set-up to ascertain the reliability of using such skeletal collections as the Terry samples to obtain data for use in establishing discriminant functions which test mandibular specimens from groups which may be temporally or genetically removed from the reference samples

Transcriptomics and methylomics of CD4-positive T cells in arsenic-exposed women

Arsenic, a carcinogen with immunotoxic effects, is a common contaminant of drinking water and certain food worldwide. We hypothesized that chronic arsenic exposure alters gene expression, potentially by altering DNA methylation of genes encoding central components of the immune system. We therefore analyzed the transcriptomes (by RNA sequencing) and methylomes (by target-enrichment next-generation sequencing) of primary CD4-positive T cells from matched groups of four women each in the Argentinean Andes, with fivefold differences in urinary arsenic concentrations (median concentrations of urinary arsenic in the lower- and high-arsenic groups: 65 and 276 μg/l, respectively). Arsenic exposure was associated with genome-wide alterations of gene expression; principal component analysis indicated that the exposure explained 53% of the variance in gene expression among the top variable genes and 19% of 28,351 genes were differentially expressed (false discovery rate 80% methylation) than the lower-arsenic group. Differentially methylated regions that were hyper-methylated in the high-arsenic group showed enrichment for immune-related gene ontologies that constitute the basic functions of CD4-positive T cells, such as isotype switching and lymphocyte activation and differentiation. In conclusion, chronic arsenic exposure from drinking water was related to changes in the transcriptome and methylome of CD4-positive T cells, both genome wide and in specific genes, supporting the hypothesis that arsenic causes immunotoxicity by interfering with gene expression and regulation