Chorioamnionitis and Subsequent Lung Function in Preterm Infants

Objective

To explore the relationship between prematurity, gender and chorioamnionitis as determinants of early life lung function in premature infants.

Methods

Placenta and membranes were collected from preterm deliveries (<37 weeks gestational age) and evaluated for histological chorioamnionitis (HCA). Patients were followed and lung function was performed in the first year of life by Raised Volume-Rapid Thoracic Compression Technique.

Results

Ninety-five infants (43 males) born prematurely (median gestational age 34.2 weeks) were recruited. HCA was detected in 66 (69%) of the placentas, and of these 55(58%) were scored HCA Grade 1, and 11(12%) HCA Grade 2. Infants exposed to HCA Grade 1 and Grade 2, when compared to those not exposed, presented significantly lower gestational ages, higher prevalence of RDS, clinical early-onset sepsis, and the use of supplemental oxygen more than 28 days. Infants exposed to HCA also had significantly lower maximal flows. There was a significant negative trend for z-scores of lung function in relation to levels of HCA; infants had lower maximal expiratory flows with increasing level of HCA. (p = 0.012 for FEF₅₀, p = 0.014 for FEF_25–75 and p = 0.32 for FEV_0.5). Two-way ANOVA adjusted for length and gestational age indicated a significant interaction between sex and HCA in determining expiratory flows (p<0.01 for FEF₅₀, FEF_25–75 and p<0.05 for FEV_0.5). Post-hoc comparisons revealed that female preterm infants exposed to HCA Grade 1 and Grade 2 had significant lower lung function than those not exposed, and this effect was not observed among males.

Conclusions

Our findings show a sex-specific negative effect of prenatal inflammation on lung function of female preterm infants. This study confirms and expands knowledge upon the known association between chorioamnionitis and early life chronic lung disease.     

Effect of Diabetes/Hyperglycemia on the Rat Retinal Adenosinergic System

The early stages of diabetic retinopathy (DR) are characterized by alterations similar to neurodegenerative and inflammatory conditions such as increased neural apoptosis, microglial cell activation and amplified production of pro-inflammatory cytokines. Adenosine regulates several physiological functions by stimulating four subtypes of receptors, A₁AR, A_2AAR, A_2BAR, and A₃AR. Although the adenosinergic signaling system is affected by diabetes in several tissues, it is unknown whether diabetic conditions in the retina can also affect it. Adenosine delivers potent suppressive effects on virtually all cells of the immune system, but its potential role in the context of DR has yet to be studied in full. In this study, we used primary mixed cultures of rat retinal cells exposed to high glucose conditions, to mimic hyperglycemia, and a streptozotocin rat model of type 1 diabetes to determine the effect diabetes/hyperglycemia have on the expression and protein levels of adenosine receptors and of the enzymes adenosine deaminase and adenosine kinase. We found elevated mRNA and protein levels of A₁AR and A_2AAR, in retinal cell cultures under high glucose conditions and a transient increase in the levels of the same receptors in diabetic retinas. Adenosine deaminase and adenosine kinase expression and protein levels showed a significant decrease in diabetic retinas 30 days after diabetes induction. An enzymatic assay performed in retinal cell cultures revealed a marked decrease in the activity of adenosine deaminase under high glucose conditions. We also found an increase in extracellular adenosine levels accompanied by a decrease in intracellular levels when retinal cells were subjected to high glucose conditions. In conclusion, this study shows that several components of the retinal adenosinergic system are affected by diabetes and high glucose conditions, and the modulation observed may uncover a possible mechanism for the alleviation of the inflammatory and excitotoxic conditions observed in diabetic retinas.     

The Pneumatron: An automated pneumatic apparatus for estimating xylem vulnerability to embolism at high temporal resolution

Xylem vulnerability to embolism represents an important trait to determine species distribution patterns and drought resistance. However, estimating embolism resistance frequently requires time-consuming and ambiguous hydraulic lab measurements. Based on a recently developed pneumatic method, we present and test the “Pneumatron”, a device that generates high time-resolution and fully automated vulnerability curves. Embolism resistance is estimated by applying a partial vacuum to extract air from an excised xylem sample, while monitoring the pressure change over time. Although the amount of gas extracted is strongly correlated with the percentage loss of xylem conductivity, validation of the Pneumatron was performed by comparison with the optical method for Eucalyptus camaldulensis leaves. The Pneumatron improved the precision of the pneumatic method considerably, facilitating the detection of small differences in the (percentage of air discharged [PAD] < 0.47%). Hence, the Pneumatron can directly measure the 50% PAD without any fitting of vulnerability curves. PAD and embolism frequency based on the optical method were strongly correlated (r² = 0.93) for E. camaldulensis. By providing an open source platform, the Pneumatron represents an easy, low-cost, and powerful tool for field measurements, which can significantly improve our understanding of plant–water relations and the mechanisms behind embolism.     

Thioredoxin h2 contributes to the redox regulation of mitochondrial photorespiratory metabolism

Thioredoxins (TRXs) are important proteins involved in redox regulation of metabolism. In plants, it has been shown that the mitochondrial metabolism is regulated by the mitochondrial TRX system. However, the functional significance of TRX h2, which is found at both cytosol and mitochondria, remains unclear. Arabidopsis plants lacking TRX h2 showed delayed seed germination and reduced respiration alongside impaired stomatal and mesophyll conductance, without impacting photosynthesis under ambient O₂ conditions. However, an increase in the stoichiometry of photorespiratory CO₂ release was found during O₂-dependent gas exchange measurements in trxh2 mutants. Metabolite profiling of trxh2 leaves revealed alterations in key metabolites of photorespiration and in several metabolites involved in respiration and amino acid metabolism. Decreased abundance of serine hydroxymethyltransferase and glycine decarboxylase (GDC) H and L subunits as well as reduced NADH/NAD⁺ ratios were also observed in trxh2 mutants. We further demonstrated that the redox status of GDC-L is altered in trxh2 mutants in vivo and that recombinant TRX h2 can deactivate GDC-L in vitro, indicating that this protein is redox regulated by the TRX system. Collectively, our results demonstrate that TRX h2 plays an important role in the redox regulation of mitochondrial photorespiratory metabolism.     

Small tropical forest trees have a greater capacity to adjust carbon metabolism to long-term drought than large canopy trees

The response of small understory trees to long-term drought is vital in determining the future composition, carbon stocks and dynamics of tropical forests. Long-term drought is, however, also likely to expose understory trees to increased light availability driven by drought-induced mortality. Relatively little is known about the potential for understory trees to adjust their physiology to both decreasing water and increasing light availability. We analysed data on maximum photosynthetic capacity (J_max, V_cmax), leaf respiration (R_leaf), leaf mass per area (LMA), leaf thickness and leaf nitrogen and phosphorus concentrations from 66 small trees across 12 common genera at the world's longest running tropical rainfall exclusion experiment and compared responses to those from 61 surviving canopy trees. Small trees increased J_max, V_cmax, R_leaf and LMA (71, 29, 32, 15% respectively) in response to the drought treatment, but leaf thickness and leaf nutrient concentrations did not change. Small trees were significantly more responsive than large canopy trees to the drought treatment, suggesting greater phenotypic plasticity and resilience to prolonged drought, although differences among taxa were observed. Our results highlight that small tropical trees have greater capacity to respond to ecosystem level changes and have the potential to regenerate resilient forests following future droughts.     

The interplay between local and landscape scales on the density of pond-dwelling anurans in subtropical grasslands

We investigated the role of local and landscape environmental variables on anurans density classified as habitat specialists and generalists in grassland landscapes, known as South Brazilian grasslands (SBG). In this region, we surveyed 187 ponds distributed over 40 landscape sampling units. For each pond, 31 local environmental variables were measured. Each landscape sampling unit was embedded within a larger regional sampling unit with different landscape properties. For each landscape and regional sampling units, 16 landscape metrics were extracted from a land cover and use map. We recorded 35 species, eleven of which are specialists in the SBG. The specialists were affected by 11 local and 2 landscape environmental variables, while generalists were affected by 14 local and one landscape environmental variable. Thus, specialists and generalists presented different relationships with local and landscape variables, but in general local variables had a greater influence on the density of anurans than the landscape variables. However, the landscape indirectly influenced local variables because higher quality ponds were in landscapes with higher percentages of natural habitat. In conclusion, reproductive sites with higher local quality and located within landscapes with higher percentages of natural grasslands are essential to conserve anurans in this habitat. Effective conservation of such sites would benefit from further studies that assess effects of land use and biotic integrity of ponds, which can help to determine (a) the relative effects of local habitat quality of ponds and (b) the effectiveness of protecting ponds and their local surroundings for anuran conservation in SBG. Abstract in Portuguese is available with online material.     

Independent evolution of song diversity and song motor performance in canaries,goldfinches and allies indicates clade-specific trade-offs in birdsong

The diversity and the motor performance of birdsongs can both be sexually selected. In wood warblers, most species with high motor performance sing a greater proportion of trills, presumably to advertise performance, and thus have lower syllable diversity. We tested if this trade-off between motor performance and syllable diversity extends to canaries, goldfinches and allies, a clade with much longer and more varied songs. We assembled a molecular phylogeny and inferred song motor performance based on the speed of frequency modulation either in trills or in within-song intervals. The two metrics of performance were positively, but only mildly, related across species. While performance evaluated in intervals had high phylogenetic signal, performance evaluated in trills changed independently of phylogeny and was constrained by body size. Species in densely vegetated habitats sang fewer trills, but did not differ in motor performance. Contrary to wood warblers, song motor performance did not predict the proportion of trilled syllables nor within-song syllable diversity, perhaps because large differences in the song duration of canaries, goldfinches and allies prevent trills from severely compromising syllable diversity. Opposed results in wood warblers and in these finches indicate the existence of clade-specific trade-offs in the evolution of birdsong.     

Species delimitation based on integrative approach suggests reallocation of genus in Hypostomini catfish (Siluriformes,Loricariidae)

Hydrobiologia - Integrative approaches are particularly useful to resolve taxonomic uncertainties in species-rich groups that have undergone explosive radiation, such as Hypostomini (suckermouth...     

Field studies of seahorse population density,structure and habitat use in a semi-closed north-eastern Mediterranean marine area (Stratoni,North Aegean Sea)

The present study was carried out in the marine area of Stratoni, Greece, where two seahorse species are present (Hippocampus hippocampus and Hippocampus guttulatus). Two surveys were conducted (September 2016 and May 2019) to gather information regarding seahorse species' abundance, distribution and habitat characteristics. Four different seahorse natural and artificial habitat types were identified. The results revealed that the presence of H. hippocampus was relatively high, especially at sites with artificial structures, whereas the presence of H. guttulatus was rare. Data collected can provide baseline information for future population assessments.