Antioxidant responses to oxidant-mediated lung diseases

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are generated throughout the human body. Enzymatic and nonenzymatic antioxidants detoxify ROS and RNS and minimize damage to biomolecules. An imbalance between the production of ROS and RNS and antioxidant capacity leads to a state of "oxidative stress" that contributes to the pathogenesis of a number of human diseases by damaging lipids, protein, and DNA. In general, lung diseases are related to inflammatory processes that generate increased ROS and RNS. The susceptibility of the lung to oxidative injury depends largely on its ability to upregulate protective ROS and RNS scavenging systems. Unfortunately, the primary intracellular antioxidants are expressed at low levels in the human lung and are not acutely induced when exposed to oxidative stresses such as cigarette smoke and hyperoxia. However, the response of extracellular antioxidant enzymes, the critical primary defense against exogenous oxidative stress, increases rapidly and in proportion to oxidative stress. In this paper, we review how antioxidants in the lung respond to oxidative stress in several lung diseases and focus on the mechanisms that upregulate extracellular glutathione peroxidase.     

A variably spliced region in the type 1 ryanodine receptor may participate in an inter-domain interaction

The aim of the present study was to examine residues that are variably spliced in the juvenile and adult isoforms of the skeletal-muscle RyR1 (type 1 ryanodine receptor). The juvenile ASI(-) splice variant is less active than the adult ASI(+) variant and is overexpressed in patients with DM (myotonic dystrophy) [Kimura, Nakamori, Lueck, Pouliquin, Aoike, Fujimura, Dirksen, Takahashi, Dulhunty and Sakoda (2005) Hum. Mol. Genet. 14, 2189-2200]. In the present study, we explore the ASI region using synthetic peptides corresponding to rabbit RyR1 residues Thr3471-Gly3500 either containing [PASI(+)] or lacking [PASI(-)] the ASI residues. Both peptides increased [3H]ryanodine binding to rabbit RyR1s, increased Ca2+ release from sarcoplasmic reti-culum vesicles and increased single RyR1 channel activity. The peptide PASI(-) was more active in each case than PASI(+). [3H]Ryanodine binding to recombinant ASI(+)RyR1 or ASI(-)-RyR1 was enhanced more by PASI(-) than PASI(+), with the greatest increase seen when PASI(-) was added to ASI(-)RyR1. The activation of the RyR channels is consistent with the hypo-thesis that the peptides interrupt an inhibitory inter-domain inter-action and that PASI(-) is more effective at interrupting this interaction than PASI(+). We therefore suggest that the ASI(-) sequence interacts more tightly than the ASI(+) sequence with its binding partner, so that the ASI(-)RyR1 is more strongly inhibited (less active) than the ASI(+)RyR1. Thus the affinity of the binding partners in this inter-domain interaction may deter-mine the activities of the mature and juvenile isoforms of RyR1 and the stronger inhibition in the juvenile isoform may contribute to the myopathy in DM.     

Negative or positive density‐dependence in movements depends on climatic seasons: The case of a Neotropical marsupial

One of the major challenges in animal ecology is to understand the factors and processes driving movement behaviour. Although density may influence movement patterns, the occurrence and nature of density‐dependence in animal movements are still unclear, particularly whether it may vary among populations of a species, or across time within a population. Here, we evaluate the occurrence and nature of density‐dependence in the movements of a Neotropical marsupial, the Grey four‐eyed opossum Philander frenatus (Didelphidae, Didelphimorphia). We quantified fine‐scale path tortuosity of individuals inhabiting continuous forest areas and forest fragments, in different climatic seasons (humid vs. super‐humid). We also determined the relative importance of population size compared to sex and body mass on movements, using a model‐selection approach. In forest fragments, path tortuosity increased with population size in the super‐humid season, but decreased in the humid season. In the continuous forest, path tortuosity was affected only by sex and body mass, being slightly higher in males and negatively related to body mass. The occurrence of density‐dependence on movements only in forest fragments is likely to reflect the higher overall density of P. frenatus in small forest fragments. The variation in the nature of density‐dependence between climatic seasons is likely to reflect a trade off between foraging over large areas (humid season, low resource availability) versus avoiding agonistic encounters (super‐humid season, high resource availability). Our results show that (i) density‐dependence in movements may be context‐dependent occurring only in areas of relatively high overall population density; and (ii) density may affect movements in different ways at different climatic seasons.     

Bibliometric indicators realities, myth and prospective

The impact factor of scientific reviews, calculated by the Institute for Scientific Information (ISI), is increasingly used to evaluate the performance of scientists and programmes. Bibliometric indicators, originally designed for other purposes than individual evaluation, are very useful tools provided their interpretation is not extrapolated beyond their limits of validity. Here we present a critical analysis of appropriate uses and misuses of bibliometric data based on case studies. We also outline anticipated consequences of new information technologies, such as electronic journals or open access schemes, on the mode of science production, evaluation and dissemination in biomedical sciences.     

Inga laurina trypsin inhibitor (ILTI) obstructs Spodoptera frugiperda trypsins expressed during adaptive mechanisms against plant protease inhibitors

Plant protease inhibitors (PIs) are elements of a common plant defense mechanism induced in response to herbivores. The fall armyworm, Spodoptera frugiperda, a highly polyphagous lepidopteran pest, responds to various PIs in its diet by expressing genes encoding trypsins. This raises the question of whether the PI‐induced trypsins are also inhibited by other PIs, which we posed as the hypothesis that Inga laurina trypsin inhibitor (ILTI) inhibits PI‐induced trypsins in S. frugiperda. In the process of testing our hypothesis, we compared its properties with those of selected PIs, soybean Kunitz trypsin inhibitor (SKTI), Inga vera trypsin inhibitor (IVTI), Adenanthera pavonina trypsin inhibitor (ApTI), and Entada acaciifolia trypsin inhibitor (EATI). We report that ILTI is more effective in inhibiting the induced S. frugiperda trypsins than SKTI and the other PIs, which supports our hypothesis. ILTI may be more appropriate than SKTI for studies regarding adaptive mechanisms to dietary PIs.     

Production of transgenic maize from bombarded type II callus: Effect of gold particle size and callus morphology on transformation efficiency

Summary Here we present a routine and efficient protocol for year-round production of fertile transgenic maize plants. Type II callus derived from maize Hi II immature zygotic embryos was transformed using the PDS 1000/He biolistic gun and selected on bialaphos. In an effort to improve the transformation protocol, the effects of gold particle size and callus morphology on transformation efficiency were investigated. Reducing gold particle size from 1.0 μm or 0.6 μm resulted in a significant increase in the rate of recovery of bialaphos-resistant clones from Type II callus. The average transformation efficiency of pre-embryogenic, early embryogenic and late embryogenic callus did not vary significantly. Rates of transformation, regeneration and fertility achieved for Type II callus are summarized and compared to those achieved for greenhouse- and field-derived immature zygotic embryos.