Tranexamic acid blocks the thrombin-mediated delay of epidermal permeability barrier recovery induced by the cedar pollen allergen, Cry j1

We previously demonstrated that Cry j1, the major pollen allergen of Cryptomeria japonica (Japanese cedar), transiently increases protease activity and intracellular Ca²⁺ concentration in cultured human keratinocytes, and delays recovery after stratum corneum barrier disruption in human skin ex vivo. Topical application of tranexamic acid or trypsin-type serine protease inhibitors accelerates barrier recovery. We hypothesized that tranexamic acid might prevent the transient protease activity increase and the barrier recovery delay induced by Cry j1. Here, we tested this hypothesis and examined the mechanism involved. In cultured human keratinocytes, knock-down of protease-activated receptor 1 (PAR-1) reduced the transient increase of calcium induced by Cry j1, whereas knock-down of PAR-2 did not. Knock-down of thrombin significantly reduced the transient increases of calcium concentration and protease activity. Tranexamic acid, soybean trypsin inhibitor, or bivalirudin (a thrombin inhibitor) also reduced the calcium elevation induced by Cry j1 and/or thrombin. Co-application of tranexamic acid or bivalirudin with Cry j1 to human skin ex vivo blocked the delay of barrier recovery. These results suggest that thrombin and PAR-1 or PAR-1-like receptor might mediate the adverse effects of Cry j1 on human epidermal keratinocytes, and could open up a new strategy for treating inflammatory skin diseases.

Studies on the carbon dioxide promotion and ethylene inhibition of tuberization in potato explants cultured in vitro

Ethylene inhibited the tuberization of etiolated potato (Solanum tuberosum L. var. Red La Soda) sprout sections cultured in vitro. Carbon dioxide did not overcome the C(2)H(4) inhibition but it was required for normal tuberization. Ethylene totally prevented root formation and development. It inhibited stolon elongation, and caused thickening and diageotropical growth of the stolon. In addition, C(2)H(4) prevented the accumulation of both starch and red anthocyanin which are always present in a tuber. Ethylene also inhibited the kinetin-increased tuberization of sprout sections.Three to five days of exposure to CO(2) were required to obtain promotion of tuberization of stolons cultured in vitro. Bicarbonate ion did not affect starch synthetase activity isolated from potato tubers in vitro. The evidence presented suggests that CO(2) gas rather than HCO(-) (3) or CO(2-) (3) ions in equilibrium with dissolved CO(2) was probably responsible for the stimulation. Morphological changes elicited by CO(2) and C(2)H(4) are described and the mechanism of action of both on tuberization is discussed.

Effect of Gibberellic Acid, Kinetin, and Ethylene plus Carbon Dioxide on the Thermodormancy of Lettuce Seed (Lactuca sativa L. cv. Mesa 659)

The effects of gibberellic acid and kinetin with ethylene plus carbon dioxide on the thermodormancy of lettuce seeds (Lactuca sativa L. cv. Mesa 659) at 35 C in the dark were studied. The combination of gibberellic acid plus kinetin with ethylene plus carbon dioxide was most effective in overcoming thermodormancy in these Great Lakes type seeds, alleviating any induced light requirement. Gibberellic acid action required at least a minimal level of ethylene plus carbon dioxide. Kinetin action was independent of ethylene plus carbon dioxide but interacted with the gases when the gases were added. A schematic representation of the interaction is presented.

Absorption and distribution of high specific radioactivity 2-C-abscisic Acid in cotton seedlings

High specific radioactivity (26.3 mc/mmole) racemic 2-(14)C-abscisic acid was synthesized. An aliquot of abscisic acid, 1.2 x 10(-4)m in aqueous methanolic solution, was applied to the surface of either a cotyledon or the first true leaf of 8- to 32-day-old cotton seedlings (Gossypium hirsutum L.). After various intervals (6-192 hours), the seedlings were processed for autoradiography, counting, and identification of the radioactivity. After 6 hours, radioactivity was observed moving basipetally out of the treated leaf toward the roots. Four days later, radioactivity could be detected throughout the whole seedling. After 8 days, 10% of the recovered radioactivity was found in the roots, and 80% remained in the treated leaf blade. Neither leaf type nor age had any effect on the abscisic acid movement or pattern of distribution. Isolated radioactivity from the roots was identified as abscisic acid, based on comparison with an authentic standard by thin layer chromatography, gas-liquid chromatography, or gas-liquid chromatography-mass spectrometry.

The role of phytochrome in an interaction with ethylene and carbon dioxide in overcoming lettuce seed thermodormancy

Ethylene and CO(2) were used to control induction of germination in thermodormant lettuce seed (Lactuca sativa L.). These experiments ultimately showed that germination depends on the presence of an active form of the phytochrome. The phytochrome system is functional and stable at 35 C, a temperature which completely inhibits germination. Phytochrome responses to red or far red light and darkness showed that this inhibition of germination under light must be due to some other block(s) rather than to a direct inactivation of the phytochrome system itself. A postred radiation increase in lettuce seed germination that is not reversed by far red light was observed. The CO(2) requirement for C(2)H(4) action is not due to a change in the medium's pH; addition of C(2)H(4) plus CO(2) at the start of imbibition did not result in as much germination as when they were added several hours after imbibition. This reduction in germination, when the gases are added at the start of imbibiton, is due to CO(2).

Interaction of carbon dioxide and ethylene in overcoming thermodormancy of lettuce seeds

The combination of ethylene with CO(2) will completely overcome the thermodormancy of lettuce (Lactuca sativa L.) seeds at 35 C. This combination is effective if it is added to seeds either at the start or after several days of imbibition. The action of ethylene is dependent upon the CO(2) level present in the atmosphere surrounding the seeds. When CO(2) is trapped by KOH the ethylene effect is essentially nil.

The conversion of 2-hydroxyethylhydrazine to ethylene

It was shown that 2-hydroxyethylhydrazine is a source of ethylene in a chemical model system. Treatment of pea seedlings produces physiological responses similar to that of ethylene. The hypothesis is advanced that 2-hydroxyethylhydrazine effects this response in pea seedlings via the release of ethylene, as was suggested earlier for its effect on abscission and flowering.

Ethylene production of ethyl propylphosphonate, niagara 10637

The response of pea seedlings (Pisum sativum var. Alaska) to ethyl propylphosphonate is similar to the effects of low levels of ethylene. Since ethyl propylphosphonate generates ethylene when exposed to oxygen in combination with a reduced metal ion, it seems probable that its plant growth-retardant properties are due to ethylene.