Methodology for Registration of Shrinkage Tumors in Head-and-Neck CT Studies.

Tumor shrinkage occurs in many patients undergoing radiotherapy for head-and-neck (H&N) cancer. However, one-to-one correspondence is not always available between voxels of two image sets. This makes intensity-based deformable registration difficult and inaccurate. In this paper, we describe a novel method to increase the performance of the registration in presence of tumor shrinkage. The method combines an image modification procedure and a fast symmetric Demons algorithm to register CT images acquired at planning and posttreatment fractions. The image modification procedure modifies the image intensities of the primary tumor by calculating tumor cell survival rate using the linear quadratic (LQ) model according to the dose delivered to the tumor. A scale operation is used to deal with uncertainties in biological parameters. The method was tested in 10 patients with nasopharyngeal cancer (NPC). Registration accuracy was improved compared with that achieved using the symmetric Demons algorithm. The average Dice similarity coefficient (DSC) increased by 21%. This novel method is suitable for H&N adaptive radiation therapy.

Exploring genotype-phenotype relationships of the LHX3 gene on growth traits in beef cattle.

The LIM-homeobox gene 3 (LHX3) plays an essential role in pituitary gland and nervous system development. Sequence variants (SVs) in coding and non-coding regions of LHX3 gene have an impact on LHX3 transcription and growth traits in cattle. Previously, we have identified 3 single nucleotide polymorphisms (SNPs: 1-3) in all exons and intron 2 regions of the LHX3 gene in cattle. Here, 7 novel SNPs (SNPs: 4-10) were identified by DNA sequencing and polymerase chain reaction single-stranded conformational polymorphism (PCR-SSCP) methods. In the present study, a total of 10 SNPs were assessed linkage disequilibrium (LD) in 802 cows representing four main cattle breeds from China (Nanyang, Qinchuan, Jiaxian, and Chinese Holstein). The assessment results demonstrated that 17 haplotypes and 18 diplotypes were revealed in these cattle populations. Moreover, association analysis indicated that the genotypes of SNPs 1-6 are associated with the body weight at 6, 12 and 18months of age in Nanyang cattle (P<0.01 or P<0.05), whereas no significant association was found between the 18 diplotypes and growth traits. Our results provide evidence that some SNPs in LHX3 gene may be associated with body weight at certain age, and LHX3 gene may be used as candidate gene for marker-assisted selection (MAS) in beef cattle breeding.

The effect of haplotype variation in the bovine PAX6 gene.

The transcription factor paired box 6 gene (PAX6) plays a key role during the early development of various organs. In this study, three single nucleotide polymorphisms (SNPs) have been identified in the introns 2, 8 and 11 of the bovine PAX6 gene. 8 haplotypes and 13 diplotypes were revealed and the linkage disequilibrium (LD) was assessed in 817 cows representing four main cattle breeds from China (Nanyang, NY; Qinchuan, QC; Jiaxian, JX; Chinese Holstein, CH). The LD analysis revealed that the additional three SNPs were not in strong LD, the wild haplotype (Hap 1: CTT) and mutant haplotype (Hap 8: TCC) have a frequency of 9.36, 35.61, 18.32, 57.15 % and 15.60, 14.19, 0.83, 0 % in the four cattle populations. The statistical analyses indicated that the SNP2 and 3 are associated with the body weight at birth, 6 and 12 months in NY and JX cattle population (P < 0.01 or P < 0.05); and significant association was detected between 19 (NY) or 13 (JX) diplotype (combined genotypes) and body weight at different ages (birth, 6 and 12 months). Our results provide evidence that some polymorphisms in PAX6 are associated with growth traits at some ages, and may be used as candidates for marker-assisted selection in beef cattle breeding program.

Study of 6³Ni adsorption on NKF-6 zeolite.

The adsorption of 6³Ni from aqueous solutions using NKF-6 zeolite was investigated by a batch technique under ambient conditions. The adsorption was investigated as a function of contact time, pH, ionic strength, foreign ions, humic substances (FA/HA) and temperature. The kinetic adsorption was well described by the pseudo-second-order rate equation. The adsorption of 6³Ni on NKF-6 zeolite was strongly dependent on pH and ionic strength, and the adsorption of 6³Ni increased with increasing NKF-6 zeolite content. At low pH values, the presence of FA enhanced the adsorption of 6³Ni on NKF-6 zeolite, but the presence of HA had no drastic effect. At high pH values, the presence of FA or HA decreased the adsorption of 6³Ni on NKF-6 zeolite. The adsorption isotherms were well represented by the Langmuir model. The thermodynamic parameters (i.e., ΔH(0), ΔS(0)and ΔG(0)) for the adsorption of 6³Ni were determined from the temperature dependent isotherms at 293.15, 313.15 and 333.15 °K, respectively, and the results indicate that the adsorption reaction was favored at high temperature. The results suggest that the adsorption process of 6³Ni on NKF-6 zeolite is spontaneous and endothermic.