Transcutaneous absorption of oil in preterm babies--a pilot study.

This study was conducted to determine transcutaneous absorption of oil in preterm neonates. A mixture of coconut oil and Meadowfoam oil which contains unique fatty acids, which acted as marker fatty acids was applied to the skin of babies. One mL blood was collected before and one hour after post oil application. Both pre and post oil application serum samples were hydrolysed and derivatised with 2-phenyl hydrazine hydrochloride in order to detect fatty acids by HPLC analysis on C-8 column. None of the pre oil application serum sample showed the presence of the marker fatty acids. The post oil application serum sample of all the 12 babies showed the presence of marker fatty acids of Meadowfoam oil which indicates transcutaneous absorption of oil in preterm babies.

Absence of kinetic barrier for transfer of protons from aqueous phase to membrane-water interface.

The kinetics of interfacial proton transfer reaction is an important factor in proton transport across membranes. The following experimental system was designed in order to measure this kinetics. Sonicated liposomes having the protonophore SF6847 was suspended in Tris buffer. Application of a temperature jump (in ~ 3 μs) caused a drop in the aqueous phase pH which was subsequently sensed by the membrane-bound SF6847. The kinetics of this interfacial proton transfer reaction was monitored on μs timescales. The estimated bimolecular rate constant of 2×1011 Μ–1 s–1 for this process show that there is no kinetic barrier for the transfer of protons from the aqueous phase to the membrane-water interface.

Histidine-15 and lytic activity of lysozyme.

The literature data on the activity of histidine-15 modified hen egg white lysozyme are conflicting: the modified enzyme is reported to have more activity, similar activity or less activity by different authors. Amino acid analysis had shown modification of the single His-15. Detailed activity studies on His-15-modified (by iodoacetic acid or diethyl pyrocarbonate) lysozyme have shown that the contradicting reports are due to the specific choices of ionic strengths and cell wall substrate concentrations and can be attributed to the substrate being negatively charged. Our analysis suggests that even though histidine-15 is far removed from the active site of lysozyme, its chemical modification or binding of the negatively-charged substrate near it, changes the conformation around the active site. However, the change in the optimum activity on chemically modifying His-15 is small.