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Trigeminal foraminal patterns in "skeletal" Class II and Class III adults--a radiocephalometric study.

Radiocephalometric analysis, based mainly on the foramina of the trigeminal nerve branches, was applied to three samples of adults, two representing fairly extreme profile types, the third representing "normal" dentofacial build. The aim of the study was to find out whether the analytical method could be used to differentiate between facial types. It appeared that some elements of the method had diagnostic powers, and could substitute for traditional methods. Many dimensions inspected, however, were fairly similar in all facial types, thus suggesting a general basic role of the trigeminal nerve in relation to craniofacial structure. Generally speaking, the foraminal pattern was relatively stable in "normal" faces, but more variable in deviant faces.

Adult↗

Distribution of HLA (class I and class II) antigens in the native Dravidian Hindus of Tamil Nadu, south India.

HLA - A, B, C, DR, DQ antigen profile of South Indian Tamil-speaking Hindus of Dravidian descent was studied. Phenotype, gene and haplotype frequencies were calculated and compared with the literature. There was a complete lack of A23, A25 and A32 antigens in the sample presently monitored. Except for minor differences (higher incidence of Cw6 and DR10 antigens), the Dravidian Hindus show similarity to North Indio-Aryan and other Hindu samples. The haplotypes A1, B17; A2, B5; A2, B51; A1, DR7; B12, DR7; B13, DR2; B17, DR7; DR2, DQ1; DR3, DQ2; DR4, DQ3; DR5, DQ3; DR7, DQ2; DR11, DQ3; show significant positive linkage disequilibrium whereas A1, DR2; DR2, DQ2; DR7, DQ1 were significant for negative linkage disequilibrium in the Dravidian Hindus.

Ethnicity↗

CD4+ T cells mature in the absence of MHC class I and class II expression in Ly-6A.2 transgenic mice.

The TCRs expressed on T lymphocytes recognize foreign peptides bound to MHC molecules. This reactivity is the basis of specific immune response to the foreign Ag. How such specificities are generated in the thymus is still being debated. Signals generated through TCR upon interaction with self MHC-peptide complexes are critical for maturation of the CD4+ helper and CD8+ cytotoxic subsets. We have observed maturation of CD4+ but not CD8+ T cells in Ly-6A.2 transgenic MHC null mice. Since there can be no interactions with MHC molecules in these mice, these CD4+ cells must express the T cell repertoire that exists before positive and negative selection. Interestingly, despite an absence of selection by MHC molecules, the CD4+ cells that mature recognize MHC molecules at a frequency as high as in CD4+ cells in normal mice. These results demonstrate that: 1) the germline sequences encoding TCRs are biased toward reactivity to MHC molecules; and 2) CD4+ cells as opposed to CD8+ cells have distinct lineage commitment signals. These results also suggest that signals originating from Ly-6 can promote or substitute for signals generated from TCR that are required for positive selection. Moreover, this animal model offers a system to study T cell development in the thymus that can provide insights into mechanisms of lineage commitment in developing T cells.

Animals↗