Tryptase and agonists of PAR-2 induce the proliferation of human airway smooth muscle cells.

Airway remodeling with smooth muscle cell (SMC) hyperplasia is a feature of chronic asthma. We investigated the potential for tryptase, the major secretory product of human mast cells, to act as a growth factor for human airway SMCs. Because this serine protease can activate proteinase-activated receptor-2 (PAR-2), we also examined the actions of SLIGKV, a peptide agonist of PAR-2. Incubation with lung tryptase provoked a twofold increase in [(3)H]thymidine incorporation; a similar increase in cell numbers was found when we used the MTS assay. The effect was catalytic site dependent, being abolished by the protease inhibitors leupeptin and benzamidine and by heat inactivation of the enzyme. Tryptase-induced DNA synthesis was inhibited by preincubation of the cells with pertussis toxin, calphostin C, or genistein. Transduction mechanisms are thus likely to involve a pertussis toxin-sensitive G protein, protein kinase C, and tyrosine kinase. SLIGKV elicited a response on SMCs similar to that of tryptase. Tryptase could provide an important stimulus for SMC proliferation in asthmatic airways, by acting on PAR-2.     

Ragweed in Australia

Ragweed (Ambrosia spp.) is awell-recognised cause of fall allergic rhinitisand seasonal asthma in the Northern Hemispherecountries of United States and Canada. InAustralia the appearance of ragweed (Ambrosia artemisiifolia) was first recordedduring the 1930s in Queensland, ragweed hayfeverwas noted in 1959 and ragweed dermatitisdocumented in 1963. Aerobiology studies performedin the capital cities of Eastern and WesternAustralia have not demonstrated ragweed pollen.This study, performed in two towns in theNorthern Rivers area of New South Wales, closeto the Queensland border, documents the ragweedseason between November 1996 and December 1997in one of the towns, by monitoring the air usinga Burkard 7-day spore trap. Two hundred and sixvolunteers were skin tested to a range ofaeroallergens including pollen of ragweed (Ambrosia artemisiifolia) and Tibouchina, a treeflowering at the same time as ragweed. 34% ofvolunteers were skin prick test positive toragweed and 5.4% to Tibouchina. The ragweedseason commenced in the first week of March andextended to early May, with the peak day pollencount, 483/m³, present in the first week ofApril. Although many residents blamed thespectacular purple Tibouchina flowers for latesummer respiratory symptoms, most were sensitiveto ragweed and not Tibouchina.     

Chronic Voluntary Ethanol Consumption Induces Favorable Ceramide Profiles in Selectively Bred Alcohol-Preferring (P) Rats

Heavy alcohol consumption has detrimental neurologic effects, inducing widespread neuronal loss in both fetuses and adults. One proposed mechanism of ethanol-induced cell loss with sufficient exposure is an elevation in concentrations of bioactive lipids that mediate apoptosis, including the membrane sphingolipid metabolites ceramide and sphingosine. While these naturally-occurring lipids serve as important modulators of normal neuronal development, elevated levels resulting from various extracellular insults have been implicated in pathological apoptosis of neurons and oligodendrocytes in several neuroinflammatory and neurodegenerative disorders. Prior work has shown that acute administration of ethanol to developing mice increases levels of ceramide in multiple brain regions, hypothesized to be a mediator of fetal alcohol-induced neuronal loss. Elevated ceramide levels have also been implicated in ethanol-mediated neurodegeneration in adult animals and humans. Here, we determined the effect of chronic voluntary ethanol consumption on lipid profiles in brain and peripheral tissues from adult alcohol-preferring (P) rats to further examine alterations in lipid composition as a potential contributor to ethanol-induced cellular damage. P rats were exposed for 13 weeks to a 20% ethanol intermittent-access drinking paradigm (45 ethanol sessions total) or were given access only to water (control). Following the final session, tissues were collected for subsequent chromatographic analysis of lipid content and enzymatic gene expression. Contrary to expectations, ethanol-exposed rats displayed substantial reductions in concentrations of ceramides in forebrain and heart relative to non-exposed controls, and modest but significant decreases in liver cholesterol. qRT-PCR analysis showed a reduction in the expression of sphingolipid delta(4)-desaturase (Degs2), an enzyme involved in de novo ceramide synthesis. These findings indicate that ethanol intake levels achieved by alcohol-preferring P rats as a result of chronic voluntary exposure may have favorable vs. detrimental effects on lipid profiles in this genetic line, consistent with data supporting beneficial cardioprotective and neuroprotective effects of moderate ethanol consumption.     

Reproductive allocation in Daphnia exposed to toxic cyanobacteria

We investigated experimentally how resources were allocated to reproduction in Daphnia pulex and Daphnia longispina when varying levels of toxic Microcystis were added to higher quality food. We used multiple regression models to estimate mean offspring size and clutch size in relation to maternal size and clutch number, and analysed effects of treatments on residuals from the models. We also measured variation in per offspring investment. At a high cyanobacterial level, D.pulex was virtually unable to reproduce. At a lower level, D.pulex produced small clutches. However, the regression model residuals indicated that the presence of cyanobacteria increased the portion of available resources allocated to reproduction. The observed allocation may be a means to maximize reproduction under diminished longevity. Effects on mean offspring size were marginal in D.pulex but variation in per offspring investment sometimes decreased in cyanobacterial exposures. Daphnia longispina was affected by a higher cyanobacterial level only, where offspring sized was reduced. Deviations from the regression model indicated that effects on maternal size alone do not explain this effect. Clutch size residuals and per offspring investment were unaffected by treatments in D.longispina. The observed responses differ from theoretical models on reproductive allocation under food imitation.      

Mechanisms for Eosinophilic and Neutrophilic Leucocytoses

Thymus-deprived mice are unable to react with eosinophilia to an appropriate stimulus, but their ability to mount a neutrophil leucocytosis in response to pyogenic infection is unimpaired. It appears that thymus-processed lymphocytes are required for induction of eosinophil but not of neutrophil leucocytosis.     

Integrating biodiversity into decision making

The prominent theme in the debates concerning biodiversity has been the integration of biodiversity into social and economical processes. Integration has meant two different but related things: on one hand, biological phenomena have been contextualized in social and economical processes; on the other hand, biological issues have been incorporated into decision making. These two aspects of integration are related: knowing the context of biodiversity helps in assessing its worth for decision making. In what follows we will first look at the ramifications of decision making, on how to proceed when dealing with apparently incommensurable dimensions. Secondly, we will highlight some key issues in both biological and social impact assessment. Finally, we will propose a process model which takes into account the multiple aspects of biodiversity.