Interactions of the dipeptide paralysin β-Ala-Tyr and the aminoacid Glu with phospholipid bilayers

AbstractExisting evidence points out that the biological activity of β-Ala-Tyr may in part related to its interactions with the cell membranes. For comparative reasons the effects of Glu were also examined using identical techniques and conditions. In order to examine their thermal and dynamic effects on membrane bilayers a combination of DSC, Raman and solid state NMR spectroscopy on DPPC/water model membranes were applied and the results were compared. DSC data showed that Glu perturbs to a greater degree the model membrane compared to β-Ala-Tyr. Thus, alteration of the phase transition temperature and half width of the peaks, abolishment of the pretransition and influence on the enthalpy of the phase transition were more pronounced in the Glu loaded bilayers. Raman spectroscopy showed that incorporation of Glu in DPPC/water bilayers increased the order in the bilayers in contrast to the effect of the dipeptide. Several structural and dynamical properties of the DPPC multilamellar bilayers with and without the dipeptide or Glu were compared using high resolution C-13 MAS (Magic Angle Spinning) spectra and spectral simulations of inhomogeneously broadened, stationary P-31 NMR lineshapes measured under CP (Cross-polarization) conditions. These methods revealed that the aminoacid Glu binds in the close realm of the phosphate in the hydrophilic headgroup of DPPC while β-Ala-Tyr is located more deeply inside the hydrophobic zone of the bilayer. The P-31 NMR simulations indicated restricted fast rotary motion of the phospholipids about their long axes in the organized bilayer structure. Finally, by the applied methodologies it is concluded that the two molecules under study exert dissimilar thermal and dynamic effects on lipid bilayers, the Glu improving significantly the packing of the lipids in contrast to the smaller and opposite effect of the dipeptide

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Bibliography: p. 62-68

Exploring the Relationship between Performance on a Series of Squat based Movement Tasks and Passive Range of Motion Capacity – Is Successful Performance a Valid Method of Ruling out Range of Motion Restrictions?

The squatting task is commonly employed as an expedient tool to evaluate the passive range of motion capacity of ankle dorsiflexion (DF-PROM) and hip flexion (HF-PROM). However, it is unclear if performance on this active task can be used to make inferences regarding the passive range of motion available at these joints. The objective of this study was to explore the relationship between DF-PROM and HF-PROM, and performance on screens consisting of low demand squat derivatives, scored using different grading criteria. Two hundred and sixty-six collegiate athletes participated in this investigation. Strong statistical evidence (pM.Sc

The Effects of Alcohol, Gender, and Sensation Seeking on the Gambling Choices of Social Drinkers

The preference-reversal, or the reflection, effect occurs when the valence of the decision option influences risk preference (A. Tversky and D. Kahneman, 1981-31998-001). The present study examined 3 possible moderators of gambling choices—alcohol, gender, and sensation seeking—among 108 healthy male and female volunteers. After receiving a moderate dose of alcohol, a placebo, or a no-alcohol control beverage, participants completed a betting task in which they could risk a monetary bonus by selecting and playing out a potential gain and a potential loss. Results indicated a preference-reversal effect among high sensation seekers only. The finding that individual differences moderated gambling choices is more consistent with L. L. Lopes\u27s (see record 1987-98851-006) security-potential/aspiration (SP/A) theory of decision making than with prospect theory. As in previous experimental studies, no significant effects were found for a moderate dose of alcohol. Using SP/A and risk homeostasis theory, the methodological and conceptual reasons for a consistent lack of an effect of alcohol on gambling choices across several studies are discussed