[ 14 KDa wound-healing peptide from the skin of the Frog Rana esculenta]

Contrary to organ regeneration which does not occur in nature, wound healing or tissue regeneration is a widespread event among all organisms. Wound healing in mammals is a multistep phenomenon. It consists of an inflammatory phase involving scavengering of damaged cells by macrophages and phagocytes whose recruitments to the site is induced by cytokines secreted by cells of wounded tissues. In the reparation phase, some differentiated cells [keratinocytes, granular cells, and fibroblasts] in the G0 phase of the cell cycle dedifferentiate, returning, along with local stem cells, to G1 phase; start dividing to ensure the needed number of differentiated cells. This mitotic activity is also regulated by specific growth factors, and a host of regulatory molecules of the immune system. These cells seem to secret a network of collagen fibers which guide their migration. The healing phase involves the formation of keratinized and apoptosing cells, forming a deciduous crust. In human, normal wound healing requires 7-8 days; in articulated regions twice this time. Here we report the purification and partial characterization of previously unknown peptide having a wound healing activity, from the dorsal skin of Rana esculenta. Isolation was carried out on column of CM-Sephadex C25. Skin proteins were eluted to peak A, B, C, and D. Peak C only has wound healing activity as demonstrated by the healing of experimental wounds made on the inner side of the rabbit's ear, covered by a thin layer of lyophilized peak C mixed with vaseline codex in ratio of 1 to 1000. The application of the ointment was done at the time of incision once only. Wound healing essays were also made on open ulcerated wounds induced on the back of rabbits injected by a mixture of known antigen with Freund adjuvant. Furthermore, wound healing essays also carried out on accidental wounds on human hands. All these wounds were treated as mentioned earlier. Further purification of peak C was carried out by FPLC on mono-Q column, and by SDS-PAGE electrophoresis. It was found that peak C consisted of two subpeaks Ca and Cb. Ca was found to have the highest wound healing activity; banded at 14 KDa. In all wound healing essays, treated wounds by the C fraction or Ca 14 KDa peptide healed at half time compared to wound controls which did not show any apparent infection

Modeling and experimental study on frequency-domain electricity properties of biological materials / 生物医学工程学杂志

Frequency-domain electricity properties of four objects, including bullfrog skin, bullfrog muscle, triply distilled water and 0.9% NaCl, were tested in the range of 100Hz-10MHz using home-made electrode and measuring system. The experimental results showed that the resistance of 0.9% NaCl decreased dramatically, that the amplitude frequency characteristics of bullfrog's muscle and skin were similar, but that of triply distilled water did not change significantly. The frequency dependence of 0.9% NaCl showed that the electrode had great influence on the measuring system, so a new equivalent circuit model based on the electrode system was needed. These findings suggest that the new five-parameter equivalent circuit model, which embodies considerations on the interaction between electrodes and tissues, is a reasonable equivalent circuit for studying the electrical characteristics of biological materials.

The study on the treatment of Oviducts Ranae protein with enzyme hydrolysis / 中国中药杂志

The paper introduced a process to enhance the yield of Oviducts Ranae protein using in vitro enzyme hydrolysis. The treatment process included two steps: (1) a 3 - 4 h of hydrolysis of a 0.025 g x g(-1) concentration of substance, at pH 7 and 60 degrees C, using 4% of papain; and (2) followed with a 6 - 8 h hydrolysis, at pH 2 - 2.5 and 60 degrees C, using 3% of pepsin. This treatment process significantly improved the lyophilized Oviducts Ranae in solubility and fluidity, which is convenient for the relative pharmaceutical preparations.

New simple ink writing pen system for kymograph recording.

Extraordinarily simple, inexpensive and easily available kymograph ink writing pen system for physiological and pharmacological recordings has been described. The writing part of the pen, consisting of a small porous fibrous writing rod to which a small spongy absorbing cylinder (as an ink container) is added, is attached to one end of a very light plastic strip of which opposite end is connected to a common mechanical lever. The function of the pen was investigated by recording spontaneous frog heart contractions in situ. The pen worked quite well and the recordings were reproducible. The pen can be interesting for researchers working in those physiology and pharmacology laboratories where more sophisticated recorders are not available, and is especially convenient for mass use in students' physiology and pharmacology labs, as alternative for smoked-drum kymograph method.

Single channel recordings from basolateral membranes of frog urinary bladders

El trabajo describe la metodología necesaria para obtener, a partir de la vejiga urinaria de la rana, capas de células aisladas apropiadas para estudios por "patch-clamp". Este resultado se logró combinando presión negativa, digestión enzimática y microdisección. Se obtuvieron registros de canales únicos en las membranas basolaterales, en una situación en la que el epitelio mantenía su polaridad y estructura general