Anti-proliferative and pro-apoptotic effects of lichen-derived compound protolichesterinic acid are not mediated by its lipoxygenase-inhibitory activity.

Lipoxygenases (LOXs) and their products are involved in several biological functions and have been associated with carcinogenesis. Protolichesterinic acid (PA), a lichen metabolite, inhibits 5- and 12-LOX and has anti-proliferative effects on various cancer cell lines. Here, PA was shown to inhibit proliferation of multiple myeloma cells, RPMI 8226 and U266, and pancreatic cancer cells AsPC-1. Apoptosis was induced only in multiple myeloma cells. Cell-cycle associated changes in expression and sub-cellular localization of 5- and 12-LOX were not affected by PA but increased cytoplasmic localisation was found to accompany morphological changes at later stages. Assessment by mass spectrometry showed that PA entered the pancreatic cancer cells. However, effects on LOX metabolites were only evident after treatment with concentrations exceeding those having anti-proliferative effects and no effects were measurable in the myeloma cells. We conclude that the anti-proliferative and pro-apoptotic effects of PA are not mediated directly through inhibition of LOX activity.

Coordinated ground forces exerted by buttocks and feet are adequately programmed for weight transfer during sit-to-stand.

The purpose of this study was to test the hypothesis whether weight transfer during sit-to-stand (STS) is the result of coordinated ground forces exerted by buttocks and feet before seat-off. Whole-body kinematics and three-dimensional ground forces from left and right buttock as well as from left and right foot were recorded for seven adults during STS. We defined a preparatory phase from onset of the first detectable anterior/posterior (A/P) force to seat-off (buttock forces fell to 0) and a rising phase from seat-off to the decrease of center of mass (CoM) vertical velocity to zero. STS was induced by an increase of vertical and backward directed ground forces exerted by the buttocks that significantly preceded the onset of any trunk movement. All ground forces peaked before or around the moment of seat-off, whereas all kinematic variables, except trunk forward rotation and hip flexion, peaked after seat-off, during or after the rising phase. The present study suggests that the weight transfer from sit to stand is induced by ground forces exerted by buttocks and feet before seat-off, i.e., during the preparatory phase. The buttocks generate the isometric "rising forces," e.g., the propulsive impulse for the forward acceleration of the body, while the feet apply adequate damping control before seat-off. This indicates that the rising movement is a result of these coordinated forces, targeted to match the subject's weight and support base distance between buttocks and feet. The single peaked, bell-shaped profiles peaking before seat-off, were seen beneath buttocks for the "rising drive," i.e., between the time of peak backward directed force and seat-off, as well as beneath the feet for the "damping drive," i.e., from onset to the peak of forward-directed force and for CoM A/P velocity. This suggests that both beginning and end of the weight transfer process are programmed before seat-off. The peak deceleration of A/P CoM took place shortly ( approximately 100 ms) after CoM peak velocity, resulting in a well controlled CoM deceleration before seat-off. In contrast to the view of other authors, this suggests that body equilibrium is controlled during weight transfer.

Performance of amino-silylated fused-silica capillaries for the separation of enkephalin-related peptides by capillary zone electrophoresis and micellar electrokinetic chromatography.

Enkephalin-related peptides were separated at low pH in a capillary with covalently bonded aminopropyl groups. The peptides are electrostatically repelled from the capillary surface and much higher efficiencies and faster separations were achieved compared to separations using uncoated capillaries. At low pH the amino groups are protonated, which results in reversed electroosmosis. The influence of voltage and ionic strength on the mobility and the separation efficiency was studied. The repeatability of migration times within one day was very good with relative standard deviations of 0.3-0.7%. Increasing the pH decreased the electroosmosis, eventually turning towards the cathode in the pH range 5-6; the separation performance, however, was lower at higher pH. Neutral and anionic micellar agents were added to the background electrolyte at different concentrations; the enkephalins had weak association with the neutral micellar agents but were distributed to the anionic taurodeoxycholic acid (TDC) micelles, giving rise to changes in separation selectivities. Very high efficiencies were obtained for peptides with a low distribution to the TDC micelles, while the efficiencies were impaired for those with a strong association with the micelles, which may indicate a slow mass transfer in the association process.

Capillary electroseparations of enkephalin-related peptides and protein kinase A peptide substrates.

The separations of enkephalin-related peptides and protein kinase A peptide substrates, with the common structural feature -Arg-Arg-X-Ser-Val-, were studied in micellar electrokinetic chromatography (MEKC) systems and compared with the capillary zone electrophoresis (CZE) mode. The influence of the magnitude and the direction of the electroosmotic flow on the selectivity was studied. Reversed electroosmosis was obtained by adding a hydrophobic amine, dimethyldodecylamine, to the background electrolyte; the amine forms cationic micelles with a low critical micelle concentration (0.3 mM). The neutral micellar agent, Brij 35, competes with the amine for adsorption sites on the capillary surface decreasing the reversed electroosmosis. In such a system, mixed cationic micelles are formed to which the peptides were not distributed at low pH, but an improved resolution was obtained due to the effects on electroosmosis. In systems containing the less hydrophobic amine dimethyloctylamine, in which probably no mixed micelles are formed, an improved separation of protein kinase A peptide substrates was obtained due to distribution to Brij 35 micelles. In separations of enkephalins, a high pH gave very low efficiencies due to surface-analyte interactions, and the best CZE separations were obtained at low pH. Changes in migration order were observed in the pH range 2-3, possibly due to differences in peptide pKa values or conformation changes of the peptides. The enkephalins were only to a small extent distributed to the Brij 35 micelles, but this improved the separation at pH 2 compared to the CZE mode.