Effects of neck damping properties on brain response underimpact loading.

In this paper, head-neck boundary conditions and modeling of the head are studied circumspectly. The neck is modeled using discrete elements and the head model is three-dimensional. In the study presented here, a viscoelastic foundation (i.e., foundation defined by both springs and dampers) concept is introduced to simulate the head-neck boundary conditions during the impact load to the head. Time histories of the brain response in finite element head models with a viscoelastic neck are compared with the corresponding solutions of finite element head models with an elastic neck, and without a neck. It is observed that the magnitude of peaks in the brain's response time histories, at a later stage (i.e., 6 to 15 ms) of the simulation, decreases when dampers are induced to the elastic neck. A parametric study is also conducted to examine the brain response while varying different damping coefficient values for the neck. The magnitude of peaks in the brain's response time histories for models with different neck damping coefficients is observed to maintain some form of proportionality. In other words, the magnitude of peaks in the brain's response time histories decreases with an increased damping coefficient of the neck at the later stage of the simulation (i.e., 6 to 15 ms). From the outcomes of this study, it can be determined that the head-neck boundary conditions during head impact loading are important for studying the brain's response at the later stages of the head impact.

Molecular characterization of the human ABO blood group orthologus system in pigs.

The selection and use of animals with blood group 0 in the process of transplanting pig organs or tissues into humans can positively contribute to the control of acute immune rejection due to differences in blood groups. Exon-specific PCRs for the porcine blood group A transferase gene against genomic DNA from either blood group A or 0 animals resulted in the amplification failure of the A0 blood group gene exon 8 from blood group 0 animals. To characterize the genetic abnormality in the genome of blood group 0 animals, we screened bacterial artificial chromosome (BAC) clones from a Korean native pig BAC library which had the blood group 0 allele, and carried out shotgun sequencing. The analysis showed that the 0 allele has a large deletion between exon 7 of the A0 blood group gene and the neighbouring SURF6. We also showed that the ABO blood group antigens in humans and the A0 blood group antigens in pigs are coded by mutations within the orthologous glycosyltransferase gene. In addition, we developed a multiplex genotyping method for the porcine A0 blood group gene.

Reporting 678 putative cSNPs from full-length enriched cDNA sequences of the Korean native pig.

Sequences from the clones of full-length enriched cDNA libraries serve as valuable resources for functional genomic studies. We have analysed 1970 high-quality chromatograms (Phred value >or= 30) that were obtained from sequencing the 5' ends of brainstem, liver, neocortex and spleen clones derived from full-length enriched cDNA libraries from Korean native pigs. In addition, 50,000 pig expressed sequence tag (EST) sequence trace files were obtained from Genbank and combined with our sequencing information to facilitate SNP identification in silico. The process generated 8118 contigs, of which 239 included minimum one sequence from Korean native pig and contained 678 putative coding single nucleotide polymorphisms (cSNPs). Of these, 33 putative cSNPs were randomly selected for confirmatory analysis and validated using 20 pigs from four different breeds (Duroc, Landrace, Yorkshire, Korean native pig). Of the 33 putative cSNPs, 20 were confirmed (61%), which was similar to the frequency reported in other studies. We also identified 15 new cSNPs from the validation process, which were not detected by our in silico analysis. Our study shows that analysing genetically diverse pig breeds including the Korean native pig could serve as a useful strategy for generating a large number of cSNPs.

A finite element method parametric study of the dynamic response of the human brain with different cerebrospinal fluid constitutive properties.

A major role for the cerebrospinal fluid (CSF) is to provide effective damping against sudden intracranial brain motions during dynamic head impact. This paper examines the roles of CSF properties on human brain responses under certain impact loadings. The brain is assumed to have a hyperviscoelastic material behaviour, while CSF is considered to be fluid-like elastic, viscoelastic, and nearly incompressible elastic with a low shear modulus and a high bulk modulus. A finite element parametric investigation on a head model under different scenarios of impact is conducted. In the study, the CSF material parameters are varied within the expected range of change, while other components of the head model are kept constant. The results indicate that the solutions from the modelling of CSF by a fluid-like medium are more realistic and support the findings of the experiment. The results also indicate that varying CSF properties did not have a major impact on the peak intracranial pressures but the impact on brain principal and shear strains are relatively significant. A sizeable impact on the relative motion of the brain, with respect to the skull, can also be observed.

A new HLA-B*40 variant, B*4073, identified by sequence-based typing in the Korean population.

A novel human leukocyte antigen-B*40 (HLA-B*40) allele was identified in the Korean population and designated HLA-B*4073. The HLA-B*4073 allele shows one nucleotide difference from B*400102 in exon 2 at nucleotide position 299 (A-->T), resulting in an amino acid change, Glu76Val.