DNA adduct formation in rat, human and hamster pancreas treated with methylnitrosourea

The methylation of cellular macromolecules with dimethylnitrosamine (DMN) and methylnitrosourea (MNU) was studied in organ cultured rat, hamster and human pancreatic explants. At concentrations of DMN and MNU that caused similar methylation of protein in human explants DMN caused only 2.6% and 0.3% of the methylation of DNA and RNA that was produced by MNU. The DNA of explants treated with MNU was analyzed. The O6-methylguanine (O6-MeG)/7-methylguanine (7-MeG) ratio was greater in the hamster DNA than in DNA isolated from either rat or human. The time course of removal of methyl adducts from DNA was followed for 6 h after treatment with MNU. No decline in O6-MeG occurred during this period in hamster explants, although there was a decline in the content of 7-MeA and 3-MeA, whereas there was removal of O6-MeG in the DNA from human pancreas explants.     

Multiple-stress analysis for isolation of Drosophila longevity genes

Long-lived organisms tend to be more resistant to various forms of environmental stress. An example is the Drosophila longevity mutant, methuselah, which has enhanced resistance to heat, oxidants, and starvation. To identify genes regulated by these three stresses, we made a cDNA library for each by subtraction of "unstressed" from "stressed" cDNA and used DNA hybridization to identify genes that are regulated by all three. This screen indeed identified 13 genes, some already known to be involved in longevity, plus candidate genes. Two of these, hsp26 and hsp27, were chosen to test for their effects on lifespan by generating transgenic lines and by using the upstream activating sequence/GAL4 system. Overexpression of either hsp26 or hsp27 extended the mean lifespan by 30%, and the flies also displayed increased stress resistance. The results demonstrate that multiple-stress screening can be used to identify new longevity genes.     

Does the tissue engineering architecture of poly(3-hydroxybutyrate) scaffold affects cell-material interactions?

A critical element in tissue engineering involves the fabrication of a three-dimensional scaffold. The scaffold provides a space for new tissue formation, supports cellular ingrowth, and proliferation and mimics many roles of the extracellular matrix. Poly(3-hydroxybutyrate) (PHB) is the most thoroughly investigated member of the polyhydroxyalkanoates (PHAs) family that has various degrees of biocompatibility and biodegradability for tissue engineering applications. In this study, we fabricated PHB scaffolds by utilizing electrospinning and salt-leaching procedures. The behavior of monkey epithelial kidney cells (Vero) and mouse mesenchymal stem cells (mMSCs) on these scaffolds was compared by the MTS assay and scanning electron microscopy. Additionally, this study investigated the mechanical and physical properties of these scaffolds by measuring tensile strength and modulus, dynamic contact angle and porosity. According to our results, the salt-leached scaffolds showed more wettability and permeability, but inferior mechanical properties when compared with nanofibrous scaffolds. In terms of cell response, salt-leached scaffolds showed enhanced Vero cell proliferation, whereas both scaffolds responded similarly in the case of mMSCs proliferation. In brief, nanofibrous scaffolds can be a better substrate for cell attachment and morphology.     

IL28B Genotype Does Not Correlate with HIV Control in African Americans

Background: HIV‐1 natural viral suppressors (NVS) are individuals that control HIV replication without antiretrovirals (also know as HIV elite controllers). We have recently shown that these individuals have an elevated rate of hepatitis C virus (HCV) clearance. Given the association of IL28B genotype, specifically the rs12979860 single nucleotide polymorphism (SNP) based CC genotype, with HCV clearance, we studied its association with HIV control in 172 African American HIV subjects and 173 race‐matched controls. Findings: The frequency of the CC genotype was 12.5% in the NVS, 14.7% in the LVL (“low viral load” cohort with 400–20,000 HIV‐1 RNA copies/mL), 17.8% in the MHVL (“medium/high viral load” cohort with >20,000 HIV‐1 RNA copies/mL), and 11.6% in an HIV‐negative cohort. There was no statistical significance in the CC genotype distribution between these cohorts (p= 0.48 between the NVS and non‐NVS HIV positive controls, p= 0.85 between NVS and HIV‐negatives). We also did not observe any association between CC genotype distribution and HIV RNA viral load, as a continuous measure. Conclusions: The IL28B CC genotype does not account for the noted HIV control in our specific NVS cohort. Further studies will be needed to determine if a common genetic factor can primarily account for any joint clearance of HCV and control of HIV. Clin Trans Sci 2011; Volume 4: 282–284     

Hypertrophy‐Associated Polymorphisms Ascertained in a Founder Cohort Applied to Heart Failure Risk and Mortality

A three‐stage approach was undertaken using genome‐wide, case‐control, and case‐only association studies to identify genetic variants associated with heart failure mortality. In an Amish founder population (n = 851), cardiac hypertrophy, a trait integral to the adaptive response to failure, was found to be heritable (h ²= 0.28, p = 0.0002) and GWAS revealed 21 candidate hypertrophy SNPs. In a case (n = 1,610)‐control (n = 463) study in unrelated Caucasians, one of the SNPs associated with hypertrophy (rs2207418, p = 8 × 10⁻⁶), was associated with heart failure, RR = 1.85(1.25–2.73, p = 0.0019). In heart failure cases rs2207418 was associated with increased mortality, HR = 1.51(1.20–1.97, p = 0.0004). There was consistency between studies, with the GG allele being associated with increased ventricular mass (˜13 g/m²) in the Amish, heart failure risk, and heart failure mortality. This SNP is in a gene desert of chromosome 20p12. Five genes are within 2.0 mbp of rs2207418 but with low LD between their SNPs and rs2207418. A region near this SNP is highly conserved in multiple vertebrates (lod score = 1,208). This conservation and the internal consistency across studies suggests that this region has biologic importance in heart failure, potentially acting as an enhancer or repressor element. rs2207418 may be useful for predicting a more progressive form of heart failure that may require aggressive therapy. Clin Trans Sci 2011; Volume 4: 17–23     

Hypertrophy-associated polymorphisms ascertained in a founder cohort applied to heart failure risk and mortality

A three-stage approach was undertaken using genome-wide, case-control, and case-only association studies to identify genetic variants associated with heart failure mortality. In an Amish founder population (n = 851), cardiac hypertrophy, a trait integral to the adaptive response to failure, was found to be heritable (h2 = 0.28, p = 0.0002) and GWAS revealed 21 candidate hypertrophy SNPs. In a case (n = 1,610)-control (n = 463) study in unrelated Caucasians, one of the SNPs associated with hypertrophy (rs2207418, p = 8 × 10??), was associated with heart failure, RR = 1.85(1.25-2.73, p = 0.0019). In heart failure cases rs2207418 was associated with increased mortality, HR = 1.51(1.20-1.97, p = 0.0004). There was consistency between studies, with the GG allele being associated with increased ventricular mass (~13 g/m2) in the Amish, heart failure risk, and heart failure mortality. This SNP is in a gene desert of chromosome 20p12. Five genes are within 2.0 mbp of rs2207418 but with low LD between their SNPs and rs2207418. A region near this SNP is highly conserved in multiple vertebrates (lod score = 1,208). This conservation and the internal consistency across studies suggests that this region has biologic importance in heart failure, potentially acting as an enhancer or repressor element. rs2207418 may be useful for predicting a more progressive form of heart failure that may require aggressive therapy.