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A novel packing materials for high-performance liquid chromatography (HPLC) was developed, which is silica gel, modified with a temperature- responsive polymer (N-isopropylacrylamide) (PNIPAAm) surface. The advantage of this system is that it works with an aqueous mobile phase, without using an organic solvent. Therefore the separation of biomolecules can be achieved without loss of their activity. In this study, we introduced a proline derivative and a naphthylalanine derivative as molecular recognition sites into PNIPAAm chains. As a result, the selectivity of separation was enhanced by CH-π interaction and π-π interaction, respectively. This result suggested that a temperature-responsive chromatography system utilizing PNIPAAm derivatives would be useful for biomolecule separation. Temperature-responsive chromatography is expected to be applicable to the separation of bioactive species in various fields, such as medical and pharmaceutical science. [ABSTRACT FROM AUTHOR]

Stretching is performed for sports activities and health. However, it is unknown how an in vivo muscle-tendon unit responds to added stretching stimulation. When stretching is performed, we need to know long the muscle-tendon unit is extended by stretching. The study aimed to determine an effective stretching time for Achilles tendon extension. Forty female subjects (mean age, 27.4 ± 3.6 years old ; mean height, 175.1 ± 9.2cm ; mean weight, 65.5 ± 10.5kg) performed stretches for his study. A marker as a landmark of the muscle-tendon junction was determined on the human medial head of the gastrocnemius muscle from ultrasonic images taken in a standing position. We set the position of the muscle-tendon junction on the skin and determined the Achilles tendon length between the mark and the calcaneal tuber length. All subjects performed static stretching on a stretching board with maximal ankle dorsiflexion. Just after stretching, we measured the Achilles tendon length by the same method as before stretching and compared measurements. The times for stretching were one, three, five and ten minutes. We carried out each measurement with intervals of at least five days. Achilles tendon extension for one minute of stretching was 3.4 ± 2.5mm, two 6.8 ± 2.1mm, three 6.9 ± 1.0mm, five 7.2 ± 0.7mm, and ten 7.4 ± 0.8mm. Achilles tendon length was significantly extended for up to two minutes of stretching (p<0.01). However, there was no significant difference for stretching for three or more minutes. From these results, we conclude that two minutes of static stretching is the most effective time for Achilles tendon extension. [ABSTRACT FROM AUTHOR]