Phylogeny and co‐occurrence of mammal species on Southeast Asian islands

Aim Islands have often been used as model systems in community ecology. The incorporation of information on phylogenetic relatedness of species in studies of island assemblage structure is still uncommon, but could provide valuable insights into the processes of island community assembly. We propose six models of island community assembly that make different predictions about the associations between co‐occurrences of species pairs on islands, phylogenetic relatedness and ecological similarity. We then test these models using data on mammals of Southeast Asian islands. Location Two hundred and forty islands of the Sundaland region of Southeast Asia. Methods We quantified the co‐occurrence of species pairs on islands, and identified pairs that co‐occur more frequently (positive co‐occurrence) or less frequently (negative co‐occurrence) than expected under null models. We then examined the distributions of these significantly deviating pairs with respect to phylogenetic relatedness and ecological differentiation, and compared these patterns with those predicted by the six community assembly models. We used permutation regression to test whether co‐occurrence patterns are predicted by relatedness, body size difference or difference in diet quality. Separate co‐occurrence matrices were analysed in this way for seven mammal families and four smaller subsets of the islands of Sundaland. Results In many matrices, average numbers of negative co‐occurrences were higher than expected under null models. This is consistent with assemblage structuring by competition, but may also result from low geographic overlap of species pairs, which contributes to negative co‐occurrences at the archipelago‐wide level. Distributions of species pairs within plots of phylogenetic distance × ecological differentiation were consistent with competition, habitat filtering or within‐island speciation models, depending on the taxon. Regressions indicated that co‐occurrence was more likely among closely related species pairs within the Viverridae and Sciuridae, but in most matrices phylogenetic distance was unrelated to co‐occurrence. Main conclusions Simple deterministic models linking co‐occurrence with phylogeny and ecology are a useful framework for interpreting distributions and assemblage structure of island species. However, island assemblages in Sundaland have probably been shaped by a complex idiosyncratic set of interacting ecological and evolutionary processes, limiting the predictive power of such models.     

Spatial and temporal expression of surfactant proteins in hyperoxia-induced neonatal rat lung injury

Background

Although personal cigarette smoking is the most important cause and modulator of chronic obstructive pulmonary disease (COPD), secondhand smoke (SHS) exposure could influence the course of the disease. Despite the importance of this question, the impact of SHS exposure on COPD health outcomes remains unknown.

Methods

We used data from two waves of a population-based multiwave U.S. cohort study of adults with COPD. 77 non-smoking respondents with a diagnosis of COPD completed direct SHS monitoring based on urine cotinine and a personal badge that measures nicotine. We evaluated the longitudinal impact of SHS exposure on validated measures of COPD severity, physical health status, quality of life (QOL), and dyspnea measured at one year follow-up.

Results

The highest level of SHS exposure, as measured by urine cotinine, was cross-sectionally associated with poorer COPD severity (mean score increment 4.7 pts; 95% CI 0.6 to 8.9) and dyspnea (1.0 pts; 95% CI 0.4 to 1.7) after controlling for covariates. In longitudinal analysis, the highest level of baseline cotinine was associated with worse COPD severity (4.7 points; 95% CI -0.1 to 9.4; p = 0.054), disease-specific QOL (2.9 pts; -0.16 to 5.9; p = 0.063), and dyspnea (0.9 pts; 95% CI 0.2 to 1.6 pts; p < 0.05), although the confidence intervals did not always exclude the no effect level.

Conclusion

Directly measured SHS exposure appears to adversely influence health outcomes in COPD, independent of personal smoking. Because SHS is a modifiable risk factor, clinicians should assess SHS exposure in their patients and counsel its avoidance. In public health terms, the effects of SHS exposure on this vulnerable subpopulation provide a further rationale for laws prohibiting public smoking.     

V gamma 1 gammadelta T cells regulate type-1/type-2 immune responses and participate in the resistance to infection and development of heart inflammation in Trypanosoma cruzi-infected BALB/c mice

Many different cell populations or lineages participate in the resistance to Trypanosoma cruzi infection. gammadelta T cells may also take part in a network of interactions that lead to control of T. cruzi infection with minimal tissue damage by controlling alphabeta T cell activation, as was previously suggested. However, the gammadelta T cell population is not homogeneous and its functions might vary, depending on T cell receptor usage or distinct stimulatory conditions. In this study, we show that the in vivo depletion of V gamma 1-bearing gammadelta T cells, prior to the infection of BALB/c mice with the Y strain of T. cruzi, induces an increased susceptibility to the infection with lower amounts of IFN-gamma being produced by conventional CD4+ or CD8+ T cells. In addition, the production of IL-4 by spleen T cells in V gamma 1-depleted mice was increased and the production of IL-10 remained unchanged. Since V gamma 1(+) gammadelta T cell depletion diminished the conversion of naive to memory/activated CD4 T cells and the production of IFN-gamma during the acute infection, these cells appear to function as helper cells for conventional CD4+ Th1 cells. Depletion of V gamma 1(+) cells also reduced the infection-induced inflammatory infiltrate in the heart and skeletal muscle. More importantly, V gamma 1(+) cells were required for up-regulation of CD40L in CD4+ and CD8+ T cells during infection. These results show that a subset of gammadelta T cells (V gamma 1(+)), which is an important component of the innate immune response, up-regulates the type 1 arm of the adaptative immune response, during T. cruzi infection.     

Automatic layout and visualization of biclusters

Background  

Biclustering has emerged as a powerful algorithmic tool for analyzing measurements of gene expression. A number of different methods have emerged for computing biclusters in gene expression data. Many of these algorithms may output a very large number of biclusters with varying degrees of overlap. There are no systematic methods that create a two-dimensional layout of the computed biclusters and display overlaps between them.     

Cork oak vulnerability to fire: the role of bark harvesting, tree characteristics and abiotic factors

Forest ecosystems where periodical tree bark harvesting is a major economic activity may be particularly vulnerable to disturbances such as fire, since debarking usually reduces tree vigour and protection against external agents. In this paper we asked how cork oak Quercus suber trees respond after wildfires and, in particular, how bark harvesting affects post-fire tree survival and resprouting. We gathered data from 22 wildfires (4585 trees) that occurred in three southern European countries (Portugal, Spain and France), covering a wide range of conditions characteristic of Q. suber ecosystems. Post-fire tree responses (tree mortality, stem mortality and crown resprouting) were examined in relation to management and ecological factors using generalized linear mixed-effects models. Results showed that bark thickness and bark harvesting are major factors affecting resistance of Q. suber to fire. Fire vulnerability was higher for trees with thin bark (young or recently debarked individuals) and decreased with increasing bark thickness until cork was 3-4 cm thick. This bark thickness corresponds to the moment when exploited trees are debarked again, meaning that exploited trees are vulnerable to fire during a longer period. Exploited trees were also more likely to be top-killed than unexploited trees, even for the same bark thickness. Additionally, vulnerability to fire increased with burn severity and with tree diameter, and was higher in trees burned in early summer or located in drier south-facing aspects. We provided tree response models useful to help estimating the impact of fire and to support management decisions. The results suggested that an appropriate management of surface fuels and changes in the bark harvesting regime (e.g. debarking coexisting trees in different years or increasing the harvesting cycle) would decrease vulnerability to fire and contribute to the conservation of cork oak ecosystems.     

Effects of exercise training on airway closure in asthmatics

We previously reported that responsiveness to methacholine (Mch) in the absence of deep inspiration (DI) decreased in healthy subjects after a short course of exercise training. We assessed whether a similar beneficial effect of exercise on airway responsiveness could occur in asthmatics. Nine patients (male/female: 3/6; mean age ± SD: 24 ± 2 yr) with mild untreated asthma [forced expiratory volume in 1 s (FEV(1)): 100 ± 7.4% pred; FEV(1)/vital capacity (VC): 90 ± 6.5%] underwent a series of single-dose Mch bronchoprovocations in the absence of DI in the course of a 10-wk training rowing program (6 h/wk of submaximal and maximal exercise), at baseline (week 0), and at week 5 and 10. The single-dose Mch was established as the dose able to induce ≥15% reduction in inspiratory vital capacity (IVC) and was administered to each subject at every challenge occasion. Five asthmatics (male/female: 1/4; mean age ± SD: 26 ± 3 yr) with similar baseline lung function (FEV(1): 102 ± 7.0% predicted; FEV(1)/VC: 83 ± 6.0%; P = 0.57 and P = 0.06, respectively) not participating in the exercise training program served as controls. In the trained group, the Mch-induced reduction in IVC from baseline was 22 ± 10% at week 0, 13 ± 11% at week 5 (P = 0.03), and 11 ± 8% at week 10 (P = 0.028). The Mch-induced reduction in FEV(1) did not change with exercise (P = 0.69). The reduction in responsiveness induced by exercise was of the same magnitude of that previously obtained in healthy subjects (50% with respect to pretraining). Conversely, Mch-induced reduction in IVC in controls remained unchanged after 10 wk (%reduction IVC at baseline: 21 ± 20%; after 10 wk: 29 ± 14%; P = 0.28). This study indicates that a short course of physical training is capable of reducing airway responsiveness in mild asthmatics.     

Five-year study of surgical rates in Ontario's counties.

The surgical rates for eight operations (hysterectomy, tonsillectomy/adenoidectomy, cholecystectomy, prostatectomy, appendectomy, mastectomy, colectomy and cesarean section) done in Ontario''s 44 counties from 1973 to 1977 were examined. There was considerable variation among the counties for all the operations studied, although the degree of intercounty variation decreased over the 5 years. Differences in resources (hospital beds and surgeons) explained little of the variation in the rates, but this may be because people crossed county lines for certain operations. Although some counties had consistently high or low rates for individual operations during the 5-year period, only four had consistently high rates for four or more operations, and only five had consistently low rates for four or more. The five counties with teaching health science centres had the highest ratios of specialists and surgeons to population, and, with the exception of one county in 1973, had above-average numbers of hospital beds. Despite the greater resources in these counties, their residents had consistently low rates for cholecystectomy, appendectomy, mastectomy and tonsillectomy/adenoidectomy. However, three of these counties had the highest rates for cesarean section. The variation in the rates is likely due to lack of agreement about indications for surgery or to variation in the use of technology rather than to differences in the incidence or prevalence of disorders.     

Ten-year trends in Canada for selected operations

Of 16 operations common in Canada the national rates over a 10-year period for the 9 discretionary procedures varied much more than those for the nondiscretionary operations. The rates of tonsillectomy and adenoidectomy, hemorrhoidectomy, varicose vein stripping and appendectomy decreased substantially, whereas those of extraction of lens, cesarean section and colectomy increased. The rates of hysterectomy and cholecystectomy first increased and then decreased. With the exception of Newfoundland the provinces generally followed these trends. Neither the Canadian nor the provincial rates were significantly associated with the availability of hospital beds or surgeons. Factors other than resources probably accounted for much of the variation among the provinces.