Comparing two polymeric biguanides: chemical distinction, antiseptic efficacy and cytotoxicity of polyaminopropyl biguanide and polyhexamethylene biguanide.

In this study, polyaminopropyl biguanide (PAPB) was compared to the molecularly closely related polyhexamethylene biguanide (PHMB) with respect to chemical relationship, antiseptic efficacy and cytotoxicity in vitro. Cytotoxicity for human keratinocytes (HaCaTs) and murine fibroblasts (L929) was determined according to ISO EN 10993-5 for both substances. Antimicrobial efficacy tests were performed via determination of the MBC, quantitative suspension method for substances and investigation of two PAPB- or PHMB-containing dressings against Staphyloccoccus aureus, Escherichia coli and Pseudomonas aeruginosa, according to international standards. Prior mass spectrometry was performed for chemical differentiation of the investigated substances. PHMB showed high toxicity even in low concentrations for both tested cell lines and a high antimicrobial efficacy against S. aureus and E. coli. In the case of PAPB, no or only low cytotoxicity was detected after 72 h, whilst comparable antibacterial features are lacking, as PAPB showed no relevant antimicrobial effects. Even though chemically closely related, PAPB proved to be ineffective in bacterial eradication, whilst PHMB showed a high efficacy. The discovery and establishment of safe and effective alternative antiseptics are important issues for the treatment of infected wounds. In particular, rising bacterial resistances to established agents, as well as ongoing discussions of potential toxic or carcinogenic effects emphasize this necessity. Nevertheless, the presented results highlight that even small changes in the chemical structure of related agents such as PHMB and PAPB can dramatically affect their efficacy and, therefore, need to be carefully distinguished and assessed side by side.

Phenotype selection reveals coevolution of muscle glycogen and protein and PTEN as a gate keeper for the accretion of muscle mass in adult female mice.

We have investigated molecular mechanisms for muscle mass accretion in a non-inbred mouse model (DU6P mice) characterized by extreme muscle mass. This extreme muscle mass was developed during 138 generations of phenotype selection for high protein content. Due to the repeated trait selection a complex setting of different mechanisms was expected to be enriched during the selection experiment. In muscle from 29-week female DU6P mice we have identified robust increases of protein kinase B activation (AKT, Ser-473, up to 2-fold) if compared to 11- and 54-week DU6P mice or controls. While a number of accepted effectors of AKT activation, including IGF-I, IGF-II, insulin/IGF-receptor, myostatin or integrin-linked kinase (ILK), were not correlated with this increase, phosphatase and tensin homologue deleted on chromosome 10 (PTEN) was down-regulated in 29-week female DU6P mice. In addition, higher levels of PTEN phosphorylation were found identifying a second mechanism of PTEN inhibition. Inhibition of PTEN and activation of AKT correlated with specific activation of p70S6 kinase and ribosomal protein S6, reduced phosphorylation of eukaryotic initiation factor 2α (eIF2α) and higher rates of protein synthesis in 29-week female DU6P mice. On the other hand, AKT activation also translated into specific inactivation of glycogen synthase kinase 3ß (GSK3ß) and an increase of muscular glycogen. In muscles from 29-week female DU6P mice a significant increase of protein/DNA was identified, which was not due to a reduction of protein breakdown or to specific increases of translation initiation. Instead our data support the conclusion that a higher rate of protein translation is contributing to the higher muscle mass in mid-aged female DU6P mice. Our results further reveal coevolution of high protein and high glycogen content during the selection experiment and identify PTEN as gate keeper for muscle mass in mid-aged female DU6P mice.

Multiplex analysis of genetic markers related to body mass index (BMI) and bone mineral density (BMD).

The multiplex analysis system described here allows simultaneous typing of one short tandem repeat (STR) and three single nucleotide polymorphisms (SNPs) that are associated with obesity and/or osteoporosis. Genes that are related to a high body mass index (BMI) and/or a high bone mineral density (BMD) are presumed to give an advantage in surviving famines. This analysis system makes it possible to genotype the (TTTA)n polymorphism of CYP19 and three SNPs, namely the rs1800795 polymorphism of IL6, the rs373 6228 polymorphism of LRP5 and the rs993 9609 polymorphism of FTO, in a single PCR amplification in recent and ancient DNA samples. Furthermore, it allows a synchronous authentication of the results with the (TATC)n polymorphism of D13S317, the (TCTA)n polymorphism of D21S11 and the (TTTC)n polymorphism of FGA in a partial genetic fingerprinting. For this purpose, PCR products for fragment-length analysis, as well as those for sequence analysis, were amplified together. After amplification, the PCR product was split into two aliquots. The first aliquot was used for fragment-length analysis and the second one for sequence analysis. The analysis system described here has been optimized for analysing ancient samples, since only minimal amounts of material are available.