Copy Number Variation in Thai Population

Copy number variation (CNV) is a major genetic polymorphism contributing to genetic diversity and human evolution. Clinical application of CNVs for diagnostic purposes largely depends on sufficient population CNV data for accurate interpretation. CNVs from general population in currently available databases help classify CNVs of uncertain clinical significance, and benign CNVs. Earlier studies of CNV distribution in several populations worldwide showed that a significant fraction of CNVs are population specific. In this study, we characterized and analyzed CNVs in 3,017 unrelated Thai individuals genotyped with the Illumina Human610, Illumina HumanOmniexpress, or Illumina HapMap550v3 platform. We employed hidden Markov model and circular binary segmentation methods to identify CNVs, extracted 23,458 CNVs consistently identified by both algorithms, and cataloged these high confident CNVs into our publicly available Thai CNV database. Analysis of CNVs in the Thai population identified a median of eight autosomal CNVs per individual. Most CNVs (96.73%) did not overlap with any known chromosomal imbalance syndromes documented in the DECIPHER database. When compared with CNVs in the 11 HapMap3 populations, CNVs found in the Thai population shared several characteristics with CNVs characterized in HapMap3. Common CNVs in Thais had similar frequencies to those in the HapMap3 populations, and all high frequency CNVs (>20%) found in Thai individuals could also be identified in HapMap3. The majorities of CNVs discovered in the Thai population, however, were of low frequency, or uniquely identified in Thais. When performing hierarchical clustering using CNV frequencies, the CNV data were clustered into Africans, Europeans, and Asians, in line with the clustering performed with single nucleotide polymorphism (SNP) data. As CNV data are specific to origin of population, our population-specific reference database will serve as a valuable addition to the existing resources for the investigation of clinical significance of CNVs in Thais and related ethnicities.     

Factors Affecting Enhanced Permeation of Amphotericin B Across Cell Membranes and Safety of Formulation

The aim of this study was to determine amphotericin B (AmB) permeation across lipid bilayer membranes mounted on Transwell® and to observe the phagocytosis of the AmB and the AmB-lipid formulations by alveolar macrophage (AM) cell lines using a fluorescence microscope. The lipid bilayer membranes were prepared from phospholipid and ergosterol as well as phospholipid and cholesterol in a ratio (67:33 mol%). AmB-lipid formulations were prepared from AmB incorporated with four lipid derivatives during a lyophilization process. In vitro cytotoxicity studies were carried out on kidney cells by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The levels of nitric oxide production by AMs exposed to these AmB-lipid formulations were determined by the Griess reaction. Phagocytosis of the AmB-lipid formulations was carried out using AM cells. The lipid bilayer membranes and AmB-lipid formulations were successfully prepared. In vitro cytotoxicity results showed less toxicity to kidney cells than pure AmB, and a 1,000-fold less production of nitric oxide by NR8383 cell lines was obtained when compared to lipopolysaccharide. Permeation results were two- to fivefold higher than for pure AmB in the ergosterol containing lipid bilayer and two- to fourfold higher than AmB in the cholesterol containing compositions, both of which were enough to kill the fungi according to their MICs and MFCs. AM phagocytosed the AmB-lipid formulations. We suggest that these products especially the AmB-sodium deoxycholate sulfate are potential candidates for targeting AM cells for the treatment of invasive pulmonary aspergillosis.