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.

Activity of volatile compounds in glandular trichomes ofLycopersicon species against two insect herbivores.

Several major chemicals in the glandular heads of type VI trichomes ofLycopersicon species were identified and quantified by gas chromatography and mass spectrometry. Two normal odd-chained ketones, 2-undecanone (47 ng) and 2-tridecanone (146 ng), and one unknown sesquiterpene (5 ng), comprised approximately 95% of the contents of a gland ofL.hirsutum f.glabratum Mull. In a closely related plant,L.hirsutum Humb. & Bonpl. (LA 361), two unknown insecticidal sesquiterpenes accounted for 6% of the gland contents. Additionally, small amounts of one unknown monoterpene and another unknown sesquiterpene were found in type VI glands of a commercial tomato variety,L.esculentum Mill. Bioassays comparing the gland exudate (by direct contact) and isooctane extracts of glands to neonate larvae ofKeiferia lycopersicella (Walsingham) (Lepidoptera: Gelechiidae) andSpodoptera exigua (Hübner) (Lepidoptera: Noctuidae) indicated that: (1) 2-tridecanone and 2-undecanone were the major insecticidal compounds inL.hirsutum f.glabratum, (2) the two unknown sesquiterpenes inL.hirsutum were acutely toxic to both species, and (3) gland contents in the commercial tomato variety provided only a physical barrier toK.lycopersicella, and were not detrimental toS.exigua. In topical bioassay trials, synthetic mixtures of 2-tridecanone and 2-undecanone (3 ∶1) demonstrated potentiation. Concentrations of these chemicals decreased as trichomes aged. Quantities of insecticidal chemicals and density of type VI trichomes varied with plant age and location within plants.

Isolation and identification of mosquito repellents inArtemisia vulgaris.

The mugwortArtemisia vulgaris L. (Compositae: Anthemideae) contains insect repellents which can be released from the plant tissues by combustion. Work was carried out to isolate and identify the repellent compounds. The dried, pulverized whole plants were steam-distilled to give a repellent essential oil which was fractionated by column chromatography. Active fractions were analyzed by capillary GC and by combined GC-MS. A number of compounds, mainly monoterpenoids, were identified. When tested as repellents against the yellow fever mosquitoAedes aegypti L. (Diptera: Culicidae), (±)-linalool, (±)-camphor, (+)-camphor, (-)-camphor, isoborneol, (-)-borneol, terpinen-4-ol, and isobornyl acetate were active at 0.14 mg/cm2 or higher. Nonanone-3, (α+ß)-thujone, and bornyl acetate were active at 0.28 mg/cm(2) or higher. ß-Pinene, myrcene, α-terpinene, (+)- limonene, and cineole were active at 1.4 mg/cm(2). Of the repellent compounds identified, terpinen-4-ol was the most active and was as effective as dimethyl phthalate.

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.

Utilization of model membranes in a test for the mechanism of ethylene action.

Reversible alteration of the surface tension of thin films of lipids, proteins and mixtures of both resulted when the thin films were treated with ethylene and other aliphatic gases. This effect appeared to be a nonspecific surface effect related to the molecular size of the gases. Ethylene produced no change which would ascribe to it any specific properties in this test system. The conductivity of an egg lecithin-cholesterol bilayer membrane separating two electrolytes was unaffected by all the test gases (including ethylene), but chloroform vapors markedly altered the conductivity in a reversible manner. In each of the test systems empoloyed, there was no specificity exhibited by ethylene, either qualitatively or quantitatively, indicating the mechanism of ethylene action cannot be explained as a simple physical effect on membranes.