The PNPLA3 Ile148Met interacts with overweight and dietary intakes on fasting triglyceride levels

The Ile148Met (rs738409, G-allele) in the patatin-like phospholipase domain-containing protein 3 gene (PNPLA3) associates with liver fat content and may lead to loss-of-function (hydrolysis) or gain-of-function (CoA-dependent lysophosphatidic acid acyltransferase) defects. PNPLA3 is up-regulated by dietary carbohydrates, and interactions between rs738409 and carbohydrates, and sugar and ω6:ω3-polyunsaturated fatty acid (PUFA) ratio on hepatic fat accumulation have been reported. We examined interaction between rs738409 and overweight, and between rs738409 and dietary intakes (carbohydrates, sucrose and ω6:ω3-PUFA ratio), on fasting triglyceride levels. From the Malmo Diet and Cancer Study-Cardiovascular Cohort, 4,827 individuals without diabetes aged 58 ± 6 years, 2,346 with BMI ≤ 25 kg/m² and 2,478 with BMI > 25 kg/m², were included in cross-sectional analyses. Dietary data were collected by a modified diet history method. Overweight modified the association between rs738409 and fasting triglyceride levels (P_interaction = 0.003). G-allele associated with lower triglycerides only among overweight individuals (P = 0.01). Nominally, significant interaction on triglyceride levels was observed between rs738409 and sucrose among normal-weight individuals (P_interaction = 0.03). G-allele associated with lower triglycerides among overweight individuals in the lowest tertiles of carbohydrate and ω6:ω3-PUFA ratio (P = 0.04 and P = 0.001) and with higher triglycerides among normal-weight individuals in the highest tertile of sucrose (P = 0.001). We conclude that overweight and dietary sucrose may modify the association between rs738409 and fasting triglyceride levels.

Electronic supplementary material

The online version of this article (doi:10.1007/s12263-014-0388-4) contains supplementary material, which is available to authorized users.     

Biosimilars--global issues, national solutions

Biotechnology derived medicinal products are presently the best characterized biologicals with considerable production and clinical experience, and have revolutionized the treatment of some of the most difficult-to-treat diseases, prolonging and improving the quality of life and patient care. They are also currently one of the fastest growing segments of the pharmaceutical industry market. The critical challenge that the biopharmaceutical industry is facing is the expiry of patents for the first generation of biopharmaceuticals, mainly recombinant DNA derived products, such as interferons, growth hormone and erythropoetin. The question that immediately arose was how should such copies of the originator products be licensed, bearing in mind that they are highly complex biological molecules produced by equally complex biological production processes with their inherent problem of biological variability. Copying biologicals is much more complex than copying small molecules and the critical issue was how to handle the licensing of products if relying in part on data from an innovator product. Since 2004 there has been considerable international consultation on how to deal with biosimilars and biological copy products. This has led to a better understanding of the challenges in the regulatory evaluation of the quality, safety and efficacy of "biosimilars", to the exchange of information between regulators, as well as to the identification of key issues. The aim of this article is to provide a brief overview of the scientific and regulatory challenges faced in developing and evaluating similar biotherapeutic products for global use. It is intended as an introduction to the series of articles in this special issue of Biologicals devoted to similar biotherapeutic products.     

Matrix effects in PIXE analysis of aerosols and ashes

A comparison of instrumental neutron activation analysis (INAA) and proton-induced X-ray emission (PIXE) results for sizefractionated atmospheric aerosols (“coarse” and “fine” fractions with an equivalent aerodynamic diameter of 2–10 Μm and < 2 Μm, respectively, or the PM10 fraction) showed that PIXE yielded significantly lower results for the PM10 and coarse fractions, especially for elements with a low Z resulting from a particle size effect. Somewhat lower PIXE results were also obtained for the fine fraction of atmospheric aerosols. A correction is also needed for irregularly shaped deposits of combustion aerosols collected by a cascade impactor in 11 size fractions ranging from 0.016 to 14.3 Μm, as well as for thick samples of fly and bottom ashes. An equivalent layer thickness (ELT) model is proposed to correct the matrix effects in PIXE. The approaches for the calculation of ELT using a comparison of PIXE and INAA results or by comparing PIXE results obtained using two different incident proton beam energies (1.31 and 2.35 MeV) are described. The correction for the ash pellets and irregular deposits are also discussed.     

Respiratory Rate as a Regulatory Factor in the Biosynthesis of the Denitrification Pathway of the Bacterium Paracoccus denitrificans

The decrease in the electron flow of the aerobic respiratory chain of the bacterium Paracoccus denitrificans, owing to either the drop in the saturation of terminal oxidases by oxygen or to the inhibition of the rate of respiration by azide or nitrite, resulted in the synthesis of dissimilatory nitrate reductase and nitrite reductase. The dependence of the resulting activities of the two enzymes (after a three-hour adaptation) on the initial value of the parameter V_max/k_La (oxidase activity of the volume unit of the culture divided by the volumetric oxygen transfer coefficient) or on the concentrations of the inhibitors had a similar form, characterized by the appearance of a maximum. The increasing parts of the obtained curves reflect the synthesis of enzymes, probably initiated by the increase in the intracellular degree of reduction, the subsequent drop being evidently in connection with the lack of metabolic energy for biosynthesis. The possible mechanisms of the effect of nitrogenous terminal acceptors (NO^-₃ and NO^-₂) on the formation of the denitrification pathway are discussed.     

Structure-Function Analysis of Heterodimer Formation,Oligomerization, and Receptor Binding of the Staphylococcus aureus Bi-component Toxin LukGH

The bi-component leukocidins of Staphylococcus aureus are important virulence factors that lyse human phagocytic cells and contribute to immune evasion. The γ-hemolysins (HlgAB and HlgCB) and Panton-Valentine leukocidin (PVL or LukSF) were shown to assemble from soluble subunits into membrane-bound oligomers on the surface of target cells, creating barrel-like pore structures that lead to cell lysis. LukGH is the most distantly related member of this toxin family, sharing only 30–40% amino acid sequence identity with the others. We observed that, unlike other leukocidin subunits, recombinant LukH and LukG had low solubility and were unable to bind to target cells, unless both components were present. Using biolayer interferometry and intrinsic tryptophan fluorescence we detected binding of LukH to LukG in solution with an affinity in the low nanomolar range and dynamic light scattering measurements confirmed formation of a heterodimer. We elucidated the structure of LukGH by x-ray crystallography at 2.8-Å resolution. This revealed an octameric structure that strongly resembles that reported for HlgAB, but with important structural differences. Structure guided mutagenesis studies demonstrated that three salt bridges, not found in other bi-component leukocidins, are essential for dimer formation in solution and receptor binding. We detected weak binding of LukH, but not LukG, to the cellular receptor CD11b by biolayer interferometry, suggesting that in common with other members of this toxin family, the S-component has the primary contact role with the receptor. These new insights provide the basis for novel strategies to counteract this powerful toxin and Staphylococcus aureus pathogenesis.     

Vernalization and photoperiod-related changes in the DNA methylation state in winter and spring rapeseed

Vernalization-induced flowering is an effect of the epigenetic regulation of gene expression through DNA methylation and histone modifications. Vernalization-mediated silencing of a floral repressor through histone modifications was shown in Arabidopsis thaliana. However, for Brassica napus L., the mechanism underlying vernalization is unclear, and the roles of DNA methylation and histone modifications have not been established. This study revealed the profiles of changes in the DNA methylation state during vernalization (after 14, 35, 56 days) and the subsequent growth in long- or short-day photoperiods (after 2, 7, 14 days) in the winter and spring rapeseed using TLC and MSAP techniques. TLC analysis showed a significant decrease in the amount of 5-methylcytosine (m⁵C) in genomic DNA in both cultivars at the beginning of vernalization, but upon its termination, the winter rape showed a reduced level of m⁵C contrary to a significantly increased level in the spring rape. MSAP analysis revealed that winter and spring rapeseed differed in the MSAP loci which were demethylated/methylated in the course of the experiment and presented diverse profiles of changes in the methylation state. The winter rape showed permanent demethylations at 69.2 % of MSAP loci in the course of vernalization that were mostly preserved upon its termination. The spring rape showed similar numbers of demethylations and methylations that were mainly transient. The study provides evidence of the role of DNA methylation in vernalization for rapeseed and for the significant prevalence of demethylations at the beginning of vernalization, which is necessary for the transition to reproductive growth.