Human intestinal hydrolysis of phenol glycosides - a study with quercetin and p-nitrophenol glycosides using ileostomy fluid

In order to study the influence of sugar moiety, aglycon structure and microflora concentration on the human ileal hydrolysis of phenol glycosides, various quercetin and p-nitrophenol glycosides were incubated under anaerobic conditions (37 degrees C for 0, 0.5, 1, 2, 4, 6, 8, 10 and 24 h) with ileostomy fluids from three different donors. The glycosides, i.e. beta-D-glucopyranosides, beta-D-galactopyranosides, alpha-L-arabinofuranosides, beta-D-xylopyranosides and alpha-L-rhamnopyranosides as well as the liberated aglycones were identified by HPLC-DAD and HPLC-ESI-MS/MS. Among the quercetin glycosides under study, the 3-O-beta-D-glucopyranoside showed with 0.22 micromol/h the highest hydrolysis rate, followed by the 3-O-beta-D-galactopyranoside, the 3-O-beta-D-xylopyranoside and the 3-O-alpha-L-arabinofuranoside (0.04 and each 0.03 micromol/h, respectively). Quercetin 3-O-alpha-L-rhamnopyranoside was found to be stable for the entire incubation period. Using quercetin 3-O-beta-D-glucopyranoside as a representative example, linear hydrolysis rate was observed from 75 to 2500 microL ileostomy fluid corresponding to its microflora content (log 0.68 up to 21.9 colony forming units). Studies performed in the presence of antibiotics did not reveal any hydrolysis. The p-nitrophenol glycosides were hydrolyzed faster than the corresponding quercetin glycosides. The hydrolysis rate decreased from the beta-D-glucopyranoside (0.41 micromol/h), to the beta-D-galactopyranoside (0.21 micromol/h), the beta-D-xylopyranoside (0.12 micromol/h), the alpha-L-arabinofuranoside (0.09 micromol/h) to the alpha-L-rhamnopyranoside (0.06 micromol/h). These results demonstrate that the human ileal hydrolysis of phenol glycosides depends on the sugar and the aglycon structure as well as the microflora.     

The on demand generation of hydrogen from Co-Ni bimetallic nano catalyst prepared by dual use of hydrogel: As template and as reactor

We report the preparation of metal nanoparticles in various formulations inside p(2-acrylamido-2-methyl-1-propansulfonic acid; p(AMPS)) hydrogels and their utilization as a catalyst in hydrolysis of NaBH₄. The swollen, flexible p(AMPS) network was used for metal ion loading and reduction in situ for the preparation of Co:Ni nanoparticles as bimetallic clusters in various formulation, and Co and Ni bimetallic catalysts as Co + Co, Co + Ni, Ni + Co and Ni + Ni. In addition to utilization of hydrogels as support materials, the p(AMPS)-metal nanoparticle system was used as catalyst to generate hydrogen in the hydrolysis of NaBH₄ with very high yield. Various parameters for the hydrolysis reaction were determined and the activation parameters were calculated. For the first time, inclusion of ferrite magnetic particles to control hydrogen generation on demand by using an externally applied magnetic field to remove the hydrogel-catalyst system from the hydrolysis medium is reported.     

Easy closure of sternotomy by the Erk needleholder

Conventional needleholders have elastic arms and lock with the aid of three or four triangle-shaped teeth ends on the arms. Because of these springs, the needle is not absolutely fixed. The Erk needleholder has thick, rigid and strong arms. Locking is obtained by the counter-balancing system and it securely holds the needle.     

Is the digestive gland of Mytilus galloprovincialis a tissue of choice for estimating cadmium exposure by means of metallothioneins?

A study performed over 12 months with caged mussels Mytilus galloprovincialis in the coastal marine zone, which is under urban pressure, reveals a temporal variation of digestive gland mass, which causes "biological dilution" of cytosolic metallothionein (MT) and trace metal (Cd, Cu, Zn, Fe, Mn) concentrations. The dilution effect was corrected by expressing the cytosolic MT and metal concentrations as the tissue content. Consequently, the changes of the average digestive gland mass coincide with the changes of MT and trace metal contents. From February to June, MT contents are nearly twice and trace metal contents nearly three times higher than those of the other months. The period of increased average digestive gland mass, of MT and trace metal contents probably overlaps with the sexual maturation of mussels (gametogenesis) and enhanced food availability. Since natural factors contribute more to the MT content than the sublethal levels of Cd, the digestive gland of M. galloprovincialis is not considered as a tissue of choice for estimating Cd exposure by means of MTs.     

Surface plasmon resonance/mass spectrometry interface

A strategy for combining surface plasmon resonance (SPR) biomolecular interaction analysis, and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is reported. Both techniques are highly complementary but need separate optimization to improve their individual specificity and sensitivity. Sensor surfaces that are optimal for kinetic analysis are not well suited for MALDI-MS and vice versa. In addition, the transfer of analyte from SPR to MS is crucial and often accompanied by sample loss. To address both of these points, a bifunctional SPR fluid cell was constructed where optimized surfaces can be used for binding studies and MS simultaneously with regard to the special need of each technique. The setup guarantees that the SPR and the loading experiment for MS are performed at identical conditions. A removable pin carries the affinity-surface-bound analyte to the mass spectrometer so that handling is minimized, avoiding analyte elution. Functionalized transfer pins can also be used independently of SPR for microaffinity capture-MS.