Contamination of therapeutic human immunoglobulin preparations with apolipoprotein H (β2‐glycoprotein I)

Polyclonal immunoglobulin (Ig) concentrates are important biological medicinal products and the assurance of their quality and safety is crucial. In our present approach we used proteomic methods to check the purity of commercial Ig products of different origin. The experimental setup included nonreducing 2DE or DIGE combined with MALDI‐TOF and the thrombin generation assay, a routine safety test for pharmaceutical Ig preparations, and was complemented by a specific immunoassay. 2DE patterns displayed contaminations with trace amounts of human apolipoprotein H (Apo‐H), transferrin, albumin, and its fragments. In contrast to the latter, Apo‐H is a protein that is active in the coagulation cascade, and thus a potential involvement in thromboembolic events in vivo cannot be excluded. It was found by 2DE and MALDI‐TOF to be a contaminant of several Ig preparations. Spiking experiments of Ig preparations with pure Apo‐H demonstrated an Apo‐H concentration dependent increase in thrombin generation assay values. Traces of Apo‐H are possibly also contributing to unwanted side effects, as already known for factor XIa. The significance of Apo‐H contaminations for these side effects might be verified by detailed analyses of pharmacovigilance data.     

First-principles calculations of structural and thermodynamic properties of β-PbO

We employed ab-initio calculations to investigate the structural and thermodynamic properties of Massicot or orthorhombic phase of PbO named β-PbO using the projector augmented-wave(PAW) method within the generalized gradient approximation(GGA). The temperature and pressure dependence of bulk modulus, heat capacity at constant pressure and constant volume, entropy, thermal expansion coefficient and Grüneisen parameter were discussed. Accuracy of two different models, the Debye and Debye-Grüneisen which are based on the quasi-harmonic approximation(QHA) for producing thermodynamic properties of material were compared. According to calculation results, these two models can be used to designate thermodynamic properties for β-PbO with sensible accuracy over a wide range of temperatures and pressures, and our work on the properties of this structure will be useful for more deeply understanding various properties of this structure.     

Concentration and pattern changes of porcine serum apolipoprotein A‐I in four different infectious diseases

Apolipoprotein A‐I (Apo A‐I) is a major protein in lipid/lipoprotein metabolism and decreased serum levels have been observed in many species in response to inflammatory and infectious challenges. Little is known about the porcine homologue, therefore in this work we have characterized it through biochemical and proteomic techniques. In 2DE, porcine serum Apo A‐I is found as three spots, the two more acidic ones corresponding to the mature protein, the more basic spot to the protein precursor. Despite high sequence coverage in LC‐MS/MS, we did not find a sequence or PTM difference between the two mature protein species. Besides this biochemical characterization, we measured overall levels and relative species abundance of serum Apo A‐I in four different viral and bacterial porcine infectious diseases. Lower overall amounts of Apo A‐I were observed in Salmonella typhimurium and Escherichia coli infections. In the 2DE protein pattern, an increase of the protein precursor together with a lower level of mature protein species were detected in the porcine circovirus type 2‐systemic disease and S. typhimurium infection. These results reveal that both the porcine serum Apo A‐I concentration and the species pattern are influenced by the nature of the infectious disease.