Morphology Observation of Two-Dimensional Monolayers of Model Proteins on Water Surface as Revealed by Dropping Method.

We have investigated the morphology of two-dimensional monolayers of gramicidin-D (GD) and alamethicin (Al) formed on the water surface by the dropping method (DM) using surface tension measurement (STm), Brewster angle microscopy (BAM), and atomic force microscopy (AFM). Dynamic light scattering (DLS) revealed that GD in alcoholic solutions formed a dimeric helical structure. According to the CD and NMR spectroscopies, GD molecules existed in dimer form in methanol and lipid membrane environments. The STm results and BAM images revealed that the GD dimer monolayer was in a liquid expanded (LE) state, whereas the Al monolayer was in a liquid condensed (LC) state. The limiting molecular area (A0) was 6.2 ± 0.5 nm2 for the GD-dimer and 3.6 ± 0.5 nm2 for the Al molecule. The AFM images also showed that the molecular long axes of both the GD-dimer and Al were horizontal to the water surface. The stability of each monolayer was confirmed by the time dependence of the surface pressure (π) observed using the STm method. The DM monolayer preparation method for GD-dimer and Al peptide molecules is a useful technique for revealing how the model biological membrane's components assemble in two dimensions on the water surface.

The Interaction between Anesthetic Isoflurane and Model-Biomembrane Monolayer Using Simultaneous Quartz Crystal Microbalance (QCM) and Quartz Crystal Impedance (QCI) Methods.

The interaction between anesthetic Isoflurane (Iso) and model-biomembrane on the water surface has been investigated using quartz crystal microbalance (QCM) and quartz crystal impedance (QCI) methods. The model-biomembranes used were dipalmitoyl phosphatidyl choline (DPPC), DPPC-palmitic acid (PA) mixture (DPPC:PA = 8:2), DPPC-Alamethicin (Al) mixture (DPPC:Al = 39:1), and DPPC-ß-Lactoglobulin (ßLG) mixture (DPPC:ßLG = 139:1) monolayers, respectively. The quartz crystal oscillator (QCO) was attached horizontally to each monolayer, and QCM and QCI measurements were performed simultaneously. It was found that Iso hydrate physisorbed on each monolayer/water interface from QCM and changed those interfacial viscosities from QCI. With an increase in Iso concentration, pure DPPC, DPPC-PA mixed, and DPPC-Al mixed monolayers showed a two-step process of Iso hydrate on both physisorption and viscosity, whereas it was a one-step for the DPPC-ßLG mixed monolayer. The viscosity change in the DPPC-ßLG mixed monolayer with the physisorption of Iso hydrate was much larger than that of other monolayers, in spite of the one-step process. From these results, the action mechanism of anesthetics and their relevance to the expression of anesthesia were discussed, based on the "release of interfacial hydrated water" hypothesis on the membrane/water interface.

Effect of Escherichia coli on phospholipid monolayers: surface tensiometry and Brewster angle microscopy measurements.

The effect of Escherichia coli (E. coli) cells on two phospholipids [dipalmitoyl phosphatidylcholine (DPPC) and dimyristoyl phosphatidylcholine (DMPC)] monolayers at the surface of a 1.5 wt% NaCl salt solution has been investigated using surface tension measurement and Brewster angle microscopy. The results showed that a DPPC monolayer that has an elastic structure was changed in morphology by interaction with E. coli cells, whereas a DMPC monolayer that has an expandable structure did not change in morphology. In particular, the morphology changed significantly around the liquid-expanded (LE)-liquid-condensed (LC) phase transition point for the DPPC monolayer. It was found that the LE-LC phase transition range in a DPPC monolayer was sensitive to influence from the outside of the monolayer such as the action of E. coli cells. Such a monolayer has the potential for application as a membrane sensor for detecting a small amount of bacteria in a short time.

Effects of mode of delivery on pro-oxidant/antioxidant balance in fetal circulation.

Objective: This study was undertaken to assess the influence of mode of delivery on the balance between pro-oxidant/antioxidant systems in fetal circulation. Materials and methods: Both umbilical arterial and venous blood samples were obtained from 37 pregnant women who delivered by spontaneous vaginal delivery (VD group) and from 29 pregnant women who delivered by elective cesarean section (CS group). Oxidative stress and antioxidant activity were evaluated by reactive oxygen metabolites (d-ROMs) and biological antioxidant potential (BAP), respectively. Results: The d-ROMs values of the VD group were higher than that of the CS group in both umbilical arterial and venous blood and these differences were found to be statistically significant (p < .01 and p < .01, respectively). The BAP values of only the umbilical arterial blood were found to be statistically significant (p < .01), with values from the VD group being higher than those of the CS group. In all measurements, the d-ROMs values averaged below 120 CARR U and BAP values averaged above 2200 µmol/L. The ratio of BAP/d-ROMs difference was found to be statistically significant (p < .01) only in the umbilical venous blood, with ratios in the VD group being lower than those in the CS group. Conclusions: Our statistical analyses suggest that vaginal delivery has an effect on increasing oxidative stress as a result of the stress of labor and that an elective cesarean section does not impair the mother's oxidative stress status. Furthermore, the high BAP values in all the measurements suggest that neonates just after birth have the ability to cope with oxidative stress. Rationale  In many studies, the diversity of views on the influence of mode of delivery on the redox status of neonates is likely to be caused by the use of different biomarkers to measure either the oxidative stress, the antioxidant activity, or both. Furthermore, incomplete explanation for sampling cord blood in these studies, either arterial, venous blood or both, complicates matters. To solve the above, this study was designed to assess the effects of mode of delivery on both pro-oxidants, via d-ROMs, and antioxidants, via BAP, in both umbilical arterial and venous blood samples obtained just after birth. There are no existing studies of BAP in both umbilical arterial and venous blood to which we can refer. In conclusion, our study suggests that the pro-oxidant/antioxidant balance in neonates just after birth is better than may be expected when compared to the potentials of adults (including pregnant mothers) according to interpretations of BAP/d-ROMs. This can be understood that neonates may have already been endowed with the ability to cope with oxidative stress, as informed by high BAP values in both umbilical arterial and venous blood. Vaginal delivery may have an effect on increasing oxidative stress as a result of the stress of labors (as measured by d-ROMs), and an elective cesarean section, which has better BAP/d-ROMs in umbilical venous blood than that of vaginal delivery, may not impair the mother's oxidative stress status.

Folded structures of L-leucylglycine oligopeptides and their aggregational behavior in aqueous solution: Raman scattering spectra and proton NMR spin-lattice relaxation studies.

The aggregational behavior of three L-leucylglycine oligopeptides (residue numbers of glycine are 3, 4, and 5) in aqueous solution was investigated by the use of Raman scattering and 1H NMR spin-lattice relaxation methods. The results indicate that their oligopeptides take up a folded structure to form dimeric aggregates above their critical aggregation concentration. The application of one-dimensional aggregate theory to these systems provides the following prediction. Elongation up to 6 glycine residues makes it possible to form dimeric aggregates, but further elongation (up to 7 glycine residues) makes the aggregates very unstable, and up to 8 or 9 glycine residues makes the formation of dimeric aggregates very difficult. The one-dimensional aggregate theory may be used to predict the existence of peptide aggregates through intermolecular hydrogen bonding.