Photodynamic targeting of EGFR does not predict the treatment outcome in combination with the EGFR tyrosine kinase inhibitor Tyrphostin AG1478

Photodynamic therapy (PDT) is a selective treatment modality against cancer. PDT is based on the preferential retention of photosensitizers (PSs), in the tumour and subsequent light exposure which activates the PS and generates reactive oxygen species. Multimodality therapy is increasingly relevant in cancer treatment and PDT has been shown as an effective adjuvant to other anti-cancer modalities. The present study reports on the combination of PDT and an epidermal growth factor receptor (EGFR) specific tyrosine kinase inhibitor (TKI), Tyrphostin AG1478. The combination was studied in two cell lines; A-431 and NuTu-19, expressing EGFR and sensitive to Tyrphostin treatment, but with different sensitivity towards photochemical EGFR damage. A-431 cells were treated with the PS meso-tetraphenylporphine with 2 sulfonate groups on adjacent phenyl rings (TPPS(2a)) in order to target mainly the endo/lysosomal compartments (18 h incubation followed by a 4 h chase in drug-free medium) or the plasma membrane (30 min incubation) upon light exposure. The EGFR was inhibited after PDT in A-431 cells only when TPPS(2a) was located on the plasma membrane, but both treatment regimes resulted in synergistic inhibition of cell growth when combined with Tyrphostin. TPPS(2a) treatment of NuTu-19 cells, designed for endo/lysosomal localization, followed by light attenuated EGFR phosphorylation but resulted in additive or antagonistic effects on cell growth when Tyrphostin was administered prior to or after PDT respectively. It was therefore concluded that photochemical damage of EGFR does not predict the treatment outcome when PDT is combined with Tyrphostin.     

Added Weights Lead to Reduced Flight Behavior and Mating Success in Polyandrous Honey Bee Queens (Apis mellifera)

Honey bee queens are exceptionally promiscuous. Early in life, queens perform one to five nuptial flights, mating with up to 44 drones. Many studies have documented potential benefits of multiple mating. In contrast, potential costs of polyandry and the sensitivity of queens to such costs have largely been ignored because they are difficult to address experimentally. To consider one aspect of mating costs to queens, the difficulty of flight, we compared flight behavior and success among a group of control queens and two experimental groups of queens that carried lead weights of two different sizes. For each queen, we assessed the number and duration of all flights and, after egg-laying commenced, the amount of stored sperm and the number of mates in terms of the offspring's patrilineal genetic diversity. Added weights quantitatively decreased the number of flights, the mean duration of flights and consequently the total time spent flying. Mating success in terms of sperm quantity and patrilines detected among the queens' offspring was also negatively impacted by the experimental manipulation. Thus, it can be concluded that the flight effort of honey bee queens during their mating period is adjusted in response to an experimentally increased cost of flying with multiple consequences for their mating success. Our results suggest that queen behavior is flexible and mating costs deserve more attention to explain the extreme polyandry in honey bees.     

A trypsin-like protease with apparent dual function in early Lepeophtheirus salmonis (Kr?yer) development

Background  

Trypsin-like serine proteases are involved in a large number of processes including digestive degradation, regulation of developmental processes, yolk degradation and yolk degradome activation. Trypsin like peptidases considered to be involved in digestion have been characterized in Lepeophtheirus salmonis. During these studies a trypsin-like peptidase which differed in a number of traits were identified.     

Pulsed electron-electron double resonance: beyond nanometre distance measurements on biomacromolecules

PELDOR (or DEER; pulsed electron-electron double resonance) is an EPR (electron paramagnetic resonance) method that measures via the dipolar electron-electron coupling distances in the nanometre range, currently 1.5-8 nm, with high precision and reliability. Depending on the quality of the data, the error can be as small as 0.1 nm. Beyond mere mean distances, PELDOR yields distance distributions, which provide access to conformational distributions and dynamics. It can also be used to count the number of monomers in a complex and allows determination of the orientations of spin centres with respect to each other. If, in addition to the dipolar through-space coupling, a through-bond exchange coupling mechanism contributes to the overall coupling both mechanisms can be separated and quantified. Over the last 10 years PELDOR has emerged as a powerful new biophysical method without size restriction to the biomolecule to be studied, and has been applied to a large variety of nucleic acids as well as proteins and protein complexes in solution or within membranes. Small nitroxide spin labels, paramagnetic metal ions, amino acid radicals or intrinsic clusters and cofactor radicals have been used as spin centres.     

Reduction in wire tension caused by dynamic loading. An experimental Ilizarov frame study

Small diameter transosseous wires are main parts of the Ilizarov frame concept. Wire tensioning is essential to gain the necessary transversal stiffness, and the wire fixators are therefore important, coupling the wire to the ring. The ability of three different wire fixator designs to maintain wire tension under dynamic loading is described. The three fixator designs were combinations of two types of bolts and one washer. In a simplified frame set-up consisting of one ring and one wire, sixty wires were dynamically loaded in sequence with 200N for 450 times and wire tension was repeatedly measured. The tension loss employing the different fixator types at two wire pretension levels (883N, 1275N) was measured. Wire slippage in the fixators and the midpoint deflection angle of the wires were measured. Large differences in fixation ability were observed. Wire fixators holding a larger and rougher contact surface had significant smaller tension loss compared to fixators with a smaller and smother contact surface. Both plastic wire deformation and slippage causes tension loss with slippage as the main contributor. Wire fixators' design can be improved in order to maintain wire tension. Such improvement could be of clinical interest enhancing the mechanical stability of the fixator.     

Do ice nucleating lipoproteins protect frozen insects against toxic chemical agents?

As the body fluid of freeze-tolerant organisms freezes, solutes become concentrated in the gradually smaller unfrozen fluid fraction, and dissolved trace metals may reach toxic levels. A dialysis technique was used to investigate the metal binding capacity of the low density fraction of the hemolymph from the freeze tolerant beetle Phyto depressus. The low density fraction, assumed to contain the ice nucleating lipoproteins, showed approximately 100 times greater capacity to bind metals (Cd ²⁺, Cu ²⁺ and Zn ²⁺) than the proteins albumin, hemoglobin and similar to metallothionein. The high metal binding capacity in the low density fraction raises the question if the ice nucleating lipoproteins might assist in detoxification of potentially toxic concentrations of metals that may occur when a large fraction of the bodyfluids of freeze tolerant insects freeze. This hypotheis is consistent with the fact that the lipoprotein ice nucleators are present in far greater amounts than required for ice nucleation, and also with the fact that the lipoprotein ice nucleators have a remarkably high content of amino acids with negatively charged residues that may act as metal binding sites.     

A Tracer Bolus Method for Investigating Glutamine Kinetics in Humans

Glutamine transport between tissues is important for the outcome of critically ill patients. Investigation of glutamine kinetics is, therefore, necessary to understand glutamine metabolism in these patients in order to improve future intervention studies. Endogenous glutamine production can be measured by continuous infusion of a glutamine tracer, which necessitates a minimum measurement time period. In order to reduce this problem, we used and validated a tracer bolus injection method. Furthermore, this method was used to measure the glutamine production in healthy volunteers in the post-absorptive state, with extra alanine and with glutamine supplementation and parenteral nutrition. Healthy volunteers received a bolus injection of [1-¹³C] glutamine, and blood was collected from the radial artery to measure tracer enrichment over 90 minutes. Endogenous rate of appearance (endoR_a) of glutamine was calculated from the enrichment decay curve and corrected for the extra glutamine supplementation. The glutamine endoR_a of healthy volunteers was 6.1±0.9 µmol/kg/min in the post-absorptive state, 6.9±1.0 µmol/kg/min with extra alanyl-glutamine (p = 0.29 versus control), 6.1±0.4 µmol/kg/min with extra alanine only (p = 0.32 versus control), and 7.5±0.9 µmol/kg/min with extra alanyl-glutamine and parenteral nutrition (p = 0.049 versus control). In conclusion, a tracer bolus injection method to measure glutamine endoR_a showed good reproducibility and small variation at baseline as well as during parenteral nutrition. Additionally, we showed that parenteral nutrition including alanyl-glutamine increased glutamine endoR_a in healthy volunteers, which was not attributable to the alanine part of the dipeptide.     

Fetal Gender and Several Cytokines Are Associated with the Number of Fetal Cells in Maternal Blood – An Observational Study

Objective

To identify factors influencing the number of fetal cells in maternal blood.

Methods

A total of 57 pregnant women at a gestational age of weeks 11–14 were included. The number of fetal cells in maternal blood was assessed in 30 ml of blood using specific markers for both enrichment and subsequent identification.

Results

Participants carrying male fetuses had a higher median number of fetal cells in maternal blood than those carrying female fetuses (5 vs. 3, p = 0.04). Certain cytokines (RANTES, IL-2 and IL-5) were significantly associated with the number of fetal cells in maternal blood.

Conclusion

The number of fetal cells in maternal blood is associated with certain cytokines and fetal gender.