Transorbital Sonographic Evaluation of Normal Optic Nerve Sheath Diameter in Healthy Volunteers in Bangladesh

Introduction

Measurement of optic nerve sheath diameter (ONSD) by ultrasound is increasingly used as a marker to detect raised intracranial pressure (ICP). ONSD varies with age and there is no clear consensus between studies for an upper limit of normal. Knowledge of normal ONSD in a healthy population is essential to interpret this measurement.

Methods

In a prospective observational study, ONSD was measured using a 15 MHz ultrasound probe in healthy volunteers in Chittagong, Bangladesh. The aims were to determine the normal range of ONSD in healthy Bangladeshi adults and children, compare measurements in males and females, horizontal and vertical beam orientations and left and right eyes in the same individual and to determine whether ONSD varies with head circumference independent of age.

Results

136 subjects were enrolled, 12.5% of whom were age 16 or under. Median ONSD was 4.41 mm with 95% of subjects in the range 4.25–4.75 mm. ONSD was bimodally distributed. There was no relationship between ONSD and age (≥4 years), gender, head circumference, and no difference in left vs right eye or horizontal vs vertical beam.

Conclusions

Ultrasonographic ONSD in Bangladeshi healthy volunteers has a narrow bimodal distribution independent of age (≥4 years), gender and head circumference. ONSD >4.75 mm in this population should be considered abnormal.     

The Intraocular Pressure under Deep versus Moderate Neuromuscular Blockade during Low-Pressure Robot Assisted Laparoscopic Radical Prostatectomy in a Randomized Trial

Background

This study aimed to determine whether continuous deep neuromuscular blockade (NMB) improves the surgical conditions and facilitates robotic-assisted laparoscopic radical prostatectomy (RALRP) under low intra-abdominal pressure (IAP) to attenuate the increase in intraocular pressure (IOP) during CO₂ pneumoperitoneum in the steep Trendelenburg (ST) position.

Methods

Sixty-seven patients undergoing RALRP were randomly assigned to a moderate NMB group (Group M), including patients who received atracurium infusion until the end of the ST position, maintaining a train of four count of 1–2; and the deep NMB group (Group D), including patients who received rocuronium infusion, maintaining a post-tetanic count of 1–2. IOP was measured in all patients at nine separate time points. All RALRPs were performed by one surgeon, who rated the overall and worst surgical conditions at the end of the ST position.

Results

The highest IOP value was observed at T4 (60 min after the ST position) in both Group M (23.3 ± 2.7 mmHg) and Group D (19.8 ± 2.1 mmHg). RALRP was accomplished at an IAP of 8 mmHg in 88% Group D patients and 25% Group M patients. The overall surgical condition grade was 4.0 (3.0–5.0) in Group D and 3.0 (2.0–5.0) in Group M (P < 0.001).

Conclusion

The current study demonstrated that continuous deep NMB may improve surgical conditions and facilitate RALRP at a low IAP, resulting in significant attenuation of the increase on IOP. Moreover, low-pressure pneumoperitoneum, facilitated by deep NMB still provided acceptable surgical conditions.

Trial Registration

ClinicalTrials.gov NCT02109133     

Influence of Acute Jugular Vein Compression on the Cerebral Blood Flow Velocity,Pial Artery Pulsation and Width of Subarachnoid Space in Humans

Purpose

The aim of this study was to assess the effect of acute bilateral jugular vein compression on: (1) pial artery pulsation (cc-TQ); (2) cerebral blood flow velocity (CBFV); (3) peripheral blood pressure; and (4) possible relations between mentioned parameters.

Methods

Experiments were performed on a group of 32 healthy 19–30 years old male subjects. cc-TQ and the subarachnoid width (sas-TQ) were measured using near-infrared transillumination/backscattering sounding (NIR-T/BSS), CBFV in the left anterior cerebral artery using transcranial Doppler, blood pressure was measured using Finapres, while end-tidal CO₂ was measured using medical gas analyser. Bilateral jugular vein compression was achieved with the use of a sphygmomanometer held on the neck of the participant and pumped at the pressure of 40 mmHg, and was performed in the bend-over (BOPT) and swayed to the back (initial) position.

Results

In the first group (n = 10) during BOPT, sas-TQ and pulse pressure (PP) decreased (−17.6% and −17.9%, respectively) and CBFV increased (+35.0%), while cc-TQ did not change (+1.91%). In the second group, in the initial position (n = 22) cc-TQ and CBFV increased (106.6% and 20.1%, respectively), while sas-TQ and PP decreases were not statistically significant (−15.5% and −9.0%, respectively). End-tidal CO₂ remained stable during BOPT and venous compression in both groups. Significant interdependence between changes in cc-TQ and PP after bilateral jugular vein compression in the initial position was found (r = −0.74).

Conclusions

Acute bilateral jugular venous insufficiency leads to hyperkinetic cerebral circulation characterised by augmented pial artery pulsation and CBFV and direct transmission of PP into the brain microcirculation. The Windkessel effect with impaired jugular outflow and more likely increased intracranial pressure is described. This study clarifies the potential mechanism linking jugular outflow insufficiency with arterial small vessel cerebral disease.     

The Role of the Carbohydrate Recognition Domain of Placental Protein 13 (PP13) in Pregnancy Evaluated with Recombinant PP13 and the DelT221 PP13 Variant

Introduction

Placental protein 13 (PP13), a placenta specific protein, is reduced in the first trimester of pregnancy in women who subsequently develop preeclampsia. A naturally occurring PP13 deletion of thymidine at position 221 (DelT₂₂₁ or truncated variant) is associated with increased frequency of severe preeclampsia. In this study we compared the full length (wildtype) PP13 and the truncated variant.

Methods

Full length PP13 or its DelT₂₂₁ variant were cloned, expressed and purified from E-Coli. Both variants were administrated into pregnant rats at day 8 of pregnancy for slow release (>5 days) through osmotic pumps and rat blood pressure was measured. Animals were sacrificed at day 15 or day 21 and their utero-placental vasculature was examined.

Results

The DelT₂₂₁ variant (11 kDA) lacked exon 4 and a part of exon 3, and is short of 2 amino acids involved in the carbohydrate (CRD) binding of the wildtype (18 kDA). Unlike the wildtype PP13, purification of DelT₂₂₁ variant required special refolding. PP13 specific poly- clonal antibodies recognized both PP13 and DelT₂₂₁ but PP13 specific monoclonal antibodies recognized only the wildtype, indicating the loss of major epitopes. Wildtype PP13 mRNA and its respective proteins were both lower in PE patients compared to normal pregnancies. The DelT₂₂₁ mutant was not found in a large Caucasian cohort. Pregnant rats exposed to wildtype or DelT₂₂₁ PP13 variants had significantly lower blood pressure compared to control. The wildtype but not the DelT₂₂₁ mutant caused extensive vein expansion.

Conclusion

This study revealed the importance of PP13 in regulating blood pressure and expanding the utero-placental vasculature in pregnant rats. PP13 mutant lacking amino acids of the PP13 CRD domain fails to cause vein expansion but did reduce blood pressure. The study provides a basis for replenishing patients at risk for preeclampsia by the full length but not the truncated PP13.     

A retrospective analysis of the haemodynamic and metabolic effects of fluid resuscitation in Vietnamese adults with severe falciparum malaria

Background

Optimising the fluid resuscitation of patients with severe malaria is a simple and potentially cost-effective intervention. Current WHO guidelines recommend central venous pressure (CVP) guided, crystalloid based, resuscitation in adults.

Methods

Prospectively collected haemodynamic data from intervention trials in Vietnamese adults with severe malaria were analysed retrospectively to assess the responses to fluid resuscitation.

Results

43 patients were studied of whom 24 received a fluid load. The fluid load resulted in an increase in cardiac index (mean increase: 0.75 L/min/m² (95% Confidence interval (CI): 0.41 to 1.1)), but no significant change in acid-base status post resuscitation (mean increase base deficit 0.6 mmol/L (95% CI: −0.1 to 1.3). The CVP and PAoP (pulmonary artery occlusion pressure) were highly inter-correlated (r_s = 0.7, p<0.0001), but neither were correlated with acid-base status (arterial pH, serum bicarbonate, base deficit) or respiratory status (PaO₂/FiO₂ ratio). There was no correlation between the oxygen delivery (DO₂) and base deficit at the 63 time-points where they were assessed simultaneously (r_s = −0.09, p = 0.46).

Conclusions

In adults with severe falciparum malaria there was no observed improvement in patient outcomes or acid-base status with fluid loading. Neither CVP nor PAoP correlated with markers of end-organ perfusion or respiratory status, suggesting these measures are poor predictors of their fluid resuscitation needs.     

Carbon dioxide enrichment does not reduce leaf longevity or alter accumulation of carbon reserves in the woodland spring ephemeral Erythronium americanum

Background and Aims

Woodland spring ephemerals exhibit a relatively short epigeous growth period prior to canopy closure. However, it has been suggested that leaf senescence is induced by a reduction in the carbohydrate sink demand, rather than by changes in light availability. To ascertain whether a potentially higher net carbon (C) assimilation rate could shorten leaf lifespan due to an accelerated rate of storage, Erythronium americanum plants were grown under ambient (400 ppm) and elevated (1100 ppm) CO₂ concentrations.

Methods

During this growth-chamber experiment, plant biomass, bulb starch concentration and cell size, leaf phenology, gas exchange rates and nutrient concentrations were monitored.

Key Results

Plants grown at 1100 ppm CO₂ had greater net C assimilation rates than those grown at 400 ppm CO₂. However, plant size, final bulb mass, bulb filling rate and timing of leaf senescence did not differ.

Conclusions

Erythronium americanum fixed more C under elevated than under ambient CO₂ conditions, but produced plants of similar size. The similar bulb growth rates under both CO₂ concentrations suggest that the bulb filling rate is dependant on bulb cell elongation rate, rather than on C availability. Elevated CO₂ stimulated leaf and bulb respiratory rates; this might reduce feed-back inhibition of photosynthesis and avoid inducing premature leaf senescence.Key words: Source–sink relations, assimilation rates, growth rates, CO₂ enrichment, respiration, spring ephemeral, leaf senescence, bulbous plant, carbohydrate storage, Erythronium americanum     

Effects of Elevated CO2 and Nitrogen Deposition on Ecosystem Carbon Fluxes on the Sanjiang Plain Wetland in Northeast China

Background

Increasing atmospheric CO₂ and nitrogen (N) deposition across the globe may affect ecosystem CO₂ exchanges and ecosystem carbon cycles. Additionally, it remains unknown how increased N deposition and N addition will alter the effects of elevated CO₂ on wetland ecosystem carbon fluxes.

Methodology/Principal Findings

Beginning in 2010, a paired, nested manipulative experimental design was used in a temperate wetland of northeastern China. The primary factor was elevated CO₂, accomplished using Open Top Chambers, and N supplied as NH₄NO₃ was the secondary factor. Gross primary productivity (GPP) was higher than ecosystem respiration (ER), leading to net carbon uptake (measured by net ecosystem CO₂ exchange, or NEE) in all four treatments over the growing season. However, their magnitude had interannual variations, which coincided with air temperature in the early growing season, with the soil temperature and with the vegetation cover. Elevated CO₂ significantly enhanced GPP and ER but overall reduced NEE because the stimulation caused by the elevated CO₂ had a greater impact on ER than on GPP. The addition of N stimulated ecosystem C fluxes in both years and ameliorated the negative impact of elevated CO₂ on NEE.

Conclusion/Significance

In this ecosystem, future elevated CO₂ may favor carbon sequestration when coupled with increasing nitrogen deposition.     

Rubisco Evolution in C4 Eudicots: An Analysis of Amaranthaceae Sensu Lato

Background

Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase) catalyses the key reaction in the photosynthetic assimilation of CO₂. In C₄ plants CO₂ is supplied to Rubisco by an auxiliary CO₂-concentrating pathway that helps to maximize the carboxylase activity of the enzyme while suppressing its oxygenase activity. As a consequence, C₄ Rubisco exhibits a higher maximum velocity but lower substrate specificity compared with the C₃ enzyme. Specific amino-acids in Rubisco are associated with C₄ photosynthesis in monocots, but it is not known whether selection has acted on Rubisco in a similar way in eudicots.

Methodology/Principal Findings

We investigated Rubisco evolution in Amaranthaceae sensu lato (including Chenopodiaceae), the third-largest family of C₄ plants, using phylogeny-based maximum likelihood and Bayesian methods to detect Darwinian selection on the chloroplast rbcL gene in a sample of 179 species. Two Rubisco residues, 281 and 309, were found to be under positive selection in C₄ Amaranthaceae with multiple parallel replacements of alanine by serine at position 281 and methionine by isoleucine at position 309. Remarkably, both amino-acids have been detected in other C₄ plant groups, such as C₄ monocots, illustrating a striking parallelism in molecular evolution.

Conclusions/Significance

Our findings illustrate how simple genetic changes can contribute to the evolution of photosynthesis and strengthen the hypothesis that parallel amino-acid replacements are associated with adaptive changes in Rubisco.     

Cotton bracts are adapted to a microenvironment of concentrated CO2 produced by rapid fruit respiration

Background and Aims

Elucidation of the mechanisms by which plants adapt to elevated CO₂ is needed; however, most studies of the mechanisms investigated the response of plants adapted to current atmospheric CO₂. The rapid respiration rate of cotton (Gossypium hirsutum) fruits (bolls) produces a concentrated CO₂ microenvironment around the bolls and bracts. It has been observed that the intercellular CO₂ concentration of a whole fruit (bract and boll) ranges from 500 to 1300 µmol mol⁻¹ depending on the irradiance, even in ambient air. Arguably, this CO₂ microenvironment has existed for at least 1·1 million years since the appearance of tetraploid cotton. Therefore, it was hypothesized that the mechanisms by which cotton bracts have adapted to elevated CO₂ will indicate how plants will adapt to future increased atmospheric CO₂ concentration. Specifically, it is hypothesized that with elevated CO₂ the capacity to regenerate ribulose-1,5-bisphosphate (RuBP) will increase relative to RuBP carboxylation.

Methods

To test this hypothesis, the morphological and physiological traits of bracts and leaves of cotton were measured, including stomatal density, gas exchange and protein contents.

Key results

Compared with leaves, bracts showed significantly lower stomatal conductance which resulted in a significantly higher water use efficiency. Both gas exchange and protein content showed a significantly greater RuBP regeneration/RuBP carboxylation capacity ratio (J_max/V_cmax) in bracts than in leaves.

Conclusions

These results agree with the theoretical prediction that adaptation of photosynthesis to elevated CO₂ requires increased RuBP regeneration. Cotton bracts are readily available material for studying adaption to elevated CO₂.     

Protein phosphatase 2A mediates dormancy of glioblastoma multiforme-derived tumor stem-like cells during hypoxia

Purpose

The hypoxic microenvironment of glioblastoma multiforme (GBM) is thought to increase resistance to cancer therapies. Recent evidence suggests that hypoxia induces protein phosphatase 2A (PP2A), a regulator of cell cycle and cell death. The effects of PP2A on GBM tumor cell proliferation and survival during hypoxic conditions have not been studied.

Experimental Design

Expression of PP2A subunits and HIF-α proteins was measured in 65 high-grade astrocytoma and 18 non-neoplastic surgical brain specimens by western blotting. PP2A activity was measured by an immunoprecipitation assay. For in vitro experiments, GBM-derived tumor stem cell-like cells (TSCs) were exposed to severe hypoxia produced by either CoCl₂ or 1% O₂. PP2A activity was inhibited either by okadaic acid or by shRNA depletion of the PP2A C subunit. Effects of PP2A activity on cell cycle progression and cell survival during hypoxic conditions were assessed using flow cytometry.

Results

In our patient cohort, PP2A activity was positively correlated with HIF-1∝ protein expression (P = 0.002). Patients with PP2A activity levels above 160 pMP had significantly worse survival compared to patients with levels below this threshold (P = 0.002). PP2A activity was an independent predictor of survival on multivariable analysis (P = 0.009). In our in vitro experiments, we confirmed that severe hypoxia induces PP2A activity in TSCs 6 hours after onset of exposure. PP2A activity mediated G1/S phase growth inhibition and reduced cellular ATP consumption in hypoxic TSCs. Conversely, inhibition of PP2A activity led to increased cell proliferation, exhaustion of intracellular ATP, and accelerated P53-independent cell death of hypoxic TSCs.

Conclusions

Our results suggest that PP2A activity predicts poor survival in GBM. PP2A appears to reduce the metabolic demand of hypoxic TSCs and enhances tumor cell survival. Modulation of PP2A may be a potential target for cancer therapy.     

Improving ecophysiological simulation models to predict the impact of elevated atmospheric CO2 concentration on crop productivity

Background

Process-based ecophysiological crop models are pivotal in assessing responses of crop productivity and designing strategies of adaptation to climate change. Most existing crop models generally over-estimate the effect of elevated atmospheric [CO₂], despite decades of experimental research on crop growth response to [CO₂].

Analysis

A review of the literature indicates that the quantitative relationships for a number of traits, once expressed as a function of internal plant nitrogen status, are altered little by the elevated [CO₂]. A model incorporating these nitrogen-based functional relationships and mechanisms simulated photosynthetic acclimation to elevated [CO₂], thereby reducing the chance of over-estimating crop response to [CO₂]. Robust crop models to have small parameterization requirements and yet generate phenotypic plasticity under changing environmental conditions need to capture the carbon–nitrogen interactions during crop growth.

Conclusions

The performance of the improved models depends little on the type of the experimental facilities used to obtain data for parameterization, and allows accurate projections of the impact of elevated [CO₂] and other climatic variables on crop productivity.     

Effect of hyperoxia and hypercapnia on tissue oxygen and perfusion response in the normal liver and kidney

Objective

Inhalation of air with altered levels of oxygen and carbon dioxide to manipulate tissue oxygenation and perfusion has both therapeutic and diagnostic value. These physiological responses can be measured non-invasively with magnetic resonance (MR) relaxation times. However, interpreting MR measurements is not straight-forward in extra-cranial organs where gas challenge studies have only begun to emerge. Inconsistent results have been reported on MR, likely because different organs respond differently. The objective of this study was to elucidate organ-specific physiological responses to gas challenge underlying MR measurements by investigating oxygenation and perfusion changes in the normal liver and kidney cortex.

Materials and Methods

Gas challenges (100% O₂, 10% CO₂, and carbogen [90% O₂+10% CO₂]) interleaved with room air was delivered to rabbits to investigate their effect on tissue oxygenation and perfusion. Real-time fiber-optic measurements of absolute oxygen and relative blood flow were made in the liver and kidney cortex.

Results

Only the liver demonstrated a vasodilatory response to CO₂. Perfusion changes to other gases were minimal in both organs. Tissue oxygenation measurements showed the liver responding only when CO₂ was present and the kidney only when O₂ was present.

Conclusion

This study reveals distinct physiological response mechanisms to gas challenge in the liver and kidney. The detailed characterization of organ-specific responses is critical to improving our understanding and interpretation of MR measurements in various body organs, and will help broaden the application of MR for non-invasive studies of gas challenges.     

High-to-Low CO(2) Acclimation Reveals Plasticity of the Photorespiratory Pathway and Indicates Regulatory Links to Cellular Metabolism of Arabidopsis

Background

Photorespiratory carbon metabolism was long considered as an essentially closed and nonregulated pathway with little interaction to other metabolic routes except nitrogen metabolism and respiration. Most mutants of this pathway cannot survive in ambient air and require CO₂-enriched air for normal growth. Several studies indicate that this CO₂ requirement is very different for individual mutants, suggesting a higher plasticity and more interaction of photorespiratory metabolism as generally thought. To understand this better, we examined a variety of high- and low-level parameters at 1% CO₂ and their alteration during acclimation of wild-type plants and selected photorespiratory mutants to ambient air.

Methodology and Principal Findings

The wild type and four photorespiratory mutants of Arabidopsis thaliana (Arabidopsis) were grown to a defined stadium at 1% CO₂ and then transferred to normal air (0.038% CO₂). All other conditions remained unchanged. This approach allowed unbiased side-by-side monitoring of acclimation processes on several levels. For all lines, diel (24 h) leaf growth, photosynthetic gas exchange, and PSII fluorescence were monitored. Metabolite profiling was performed for the wild type and two mutants. During acclimation, considerable variation between the individual genotypes was detected in many of the examined parameters, which correlated with the position of the impaired reaction in the photorespiratory pathway.

Conclusions

Photorespiratory carbon metabolism does not operate as a fully closed pathway. Acclimation from high to low CO₂ was typically steady and consistent for a number of features over several days, but we also found unexpected short-term events, such as an intermittent very massive rise of glycine levels after transition of one particular mutant to ambient air. We conclude that photorespiration is possibly exposed to redox regulation beyond known substrate-level effects. Additionally, our data support the view that 2-phosphoglycolate could be a key regulator of photosynthetic-photorespiratory metabolism as a whole.     

Mechanical ventilation with high tidal volumes attenuates myocardial dysfunction by decreasing cardiac edema in a rat model of LPS-induced peritonitis

Background

Injurious mechanical ventilation (MV) may augment organ injury remote from the lungs. During sepsis, myocardial dysfunction is common and increased endothelial activation and permeability can cause myocardial edema, which may, among other factors, hamper myocardial function. We investigated the effects of MV with injuriously high tidal volumes on the myocardium in an animal model of sepsis.

Methods

Normal rats and intraperitoneal (i.p.) lipopolysaccharide (LPS)-treated rats were ventilated with low (6 ml/kg) and high (19 ml/kg) tidal volumes (Vt) under general anesthesia. Non-ventilated animals served as controls. Mean arterial pressure (MAP), central venous pressure (CVP), cardiac output (CO) and pulmonary plateau pressure (P_plat) were measured. Ex vivo myocardial function was measured in isolated Langendorff-perfused hearts. Cardiac expression of endothelial vascular cell adhesion molecule (VCAM)-1 and edema were measured to evaluate endothelial inflammation and leakage.

Results

MAP decreased after LPS-treatment and Vt-dependently, both independent of each other and with interaction. MV Vt-dependently increased CVP and Pplat and decreased CO. LPS-induced peritonitis decreased myocardial function ex vivo but MV attenuated systolic dysfunction Vt-dependently. Cardiac endothelial VCAM-1 expression was increased by LPS treatment independent of MV. Cardiac edema was lowered Vt-dependently by MV, particularly after LPS, and correlated inversely with systolic myocardial function parameters ex vivo.

Conclusion

MV attenuated LPS-induced systolic myocardial dysfunction in a Vt-dependent manner. This was associated with a reduction in cardiac edema following a lower transmural coronary venous outflow pressure during LPS-induced coronary inflammation.     

Developing pulmonary vasculopathy in systemic sclerosis, detected with non-invasive cardiopulmonary exercise testing

Background

Patients with systemic sclerosis (SSc) may develop exercise intolerance due to musculoskeletal involvement, restrictive lung disease, left ventricular dysfunction, or pulmonary vasculopathy (PV). The latter is particularly important since it may lead to lethal pulmonary arterial hypertension (PAH). We hypothesized that abnormalities during cardiopulmonary exercise testing (CPET) in patients with SSc can identify PV leading to overt PAH.

Methods

Thirty SSc patients from the Harbor-UCLA Rheumatology clinic, not clinically suspected of having significant pulmonary vascular disease, were referred for this prospective study. Resting pulmonary function and exercise gas exchange were assessed, including peakVO₂, anaerobic threshold (AT), heart rate- VO₂ relationship (O₂-pulse), exercise breathing reserve and parameters of ventilation-perfusion mismatching, as evidenced by elevated ventilatory equivalent for CO₂ (VE/VCO₂) and reduced end-tidal pCO₂ (P_ETCO₂) at the AT.

Results

Gas exchange patterns were abnormal in 16 pts with specific cardiopulmonary disease physiology: Eleven patients had findings consistent with PV, while five had findings consistent with left-ventricular dysfunction (LVD). Although both groups had low peak VO₂ and AT, a higher VE/VCO₂ at AT and decreasing P_ETCO₂ during early exercise distinguished PV from LVD.

Conclusions

Previously undiagnosed exercise impairments due to LVD or PV were common in our SSc patients. Cardiopulmonary exercise testing may help to differentiate and detect these disorders early in patients with SSc.     

Leaf traits, shoot growth and seed production in mature Fagus sylvatica trees after 8 years of CO2 enrichment

Background and Aims

Masting, i.e. synchronous but highly variable interannual seed production, is a strong sink for carbon and nutrients. It may, therefore, compete with vegetative growth. It is currently unknown whether increased atmospheric CO₂ concentrations will affect the carbon balance (or that of other nutrients) between reproduction and vegetative growth of forest species. In this study, reproduction and vegetative growth of shoots of mature beech (Fagus sylvatica) trees grown at ambient and elevated atmospheric CO₂ concentrations were quantified. It was hypothesized that within a shoot, fruiting has a negative effect on vegetative growth, and that this effect is ameliorated at increased CO₂ concentrations.

Methods

Reproduction and its competition with leaf and shoot production were examined during two masting events (in 2007 and 2009) in F. sylvatica trees that had been exposed to either ambient or elevated CO₂ concentrations (530 µmol mol⁻¹) for eight consecutive years, between 2000 and 2008.

Key Results

The number of leaves per shoot and the length of terminal shoots was smaller or shorter in the two masting years compared with the one non-masting year (2008) investigated, but they were unaffected by elevated CO₂ concentrations. The dry mass of terminal shoots was approx. 2-fold lower in the masting year (2007) than in the non-masting year in trees growing at ambient CO₂ concentrations, but this decline was not observed in trees exposed to elevated CO₂ concentrations. In both the CO₂ treatments, fruiting significantly decreased nitrogen concentration by 25 % in leaves and xylem tissue of 1- to 3-year-old branches in 2009.

Conclusions

Our findings indicate that there is competition for resources between reproduction and shoot growth. Elevated CO₂ concentrations reduced this competition, indicating effects on the balance of resource allocation between reproduction and vegetative growth in shoots with rising atmospheric CO₂ concentrations.     

Complete sequencing of Novosphingobium sp. PP1Y reveals a biotechnologically meaningful metabolic pattern

Background

Novosphingobium sp. strain PP1Y is a marine α-proteobacterium adapted to grow at the water/fuel oil interface. It exploits the aromatic fraction of fuel oils as a carbon and energy source. PP1Y is able to grow on a wide range of mono-, poly- and heterocyclic aromatic hydrocarbons. Here, we report the complete functional annotation of the whole Novosphingobium genome.

Results

PP1Y genome analysis and its comparison with other Sphingomonadal genomes has yielded novel insights into the molecular basis of PP1Y’s phenotypic traits, such as its peculiar ability to encapsulate and degrade the aromatic fraction of fuel oils. In particular, we have identified and dissected several highly specialized metabolic pathways involved in: (i) aromatic hydrocarbon degradation; (ii) resistance to toxic compounds; and (iii) the quorum sensing mechanism.

Conclusions

In summary, the unraveling of the entire PP1Y genome sequence has provided important insight into PP1Y metabolism and, most importantly, has opened new perspectives about the possibility of its manipulation for bioremediation purposes.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-384) contains supplementary material, which is available to authorized users.     

The Single-Breath Diffusing Capacity of CO and NO in Healthy Children of European Descent

Rationale

The diffusing capacity (D_L) of the lung can be divided into two components: the diffusing capacity of the alveolar membrane (Dm) and the pulmonary capillary volume (Vc). D_L is traditionally measured using a single-breath method, involving inhalation of carbon monoxide, and a breath hold of 8–10 seconds (D_L,CO). This method does not easily allow calculation of Dm and Vc. An alternative single-breath method (D_L,CO,NO), involving simultaneous inhalation of carbon monoxide and nitric oxide, and traditionally a shorter breath hold, allows calculation of Dm and Vc and the D_L,NO/D_L,CO ratio in a single respiratory maneuver. The clinical utility of Dm, Vc, and D_L,NO/D_L,CO in the pediatric age range is currently unknown but also restricted by lack of reference values.

Objectives

The aim of this study was to establish reference ranges for the outcomes of D_L,CO,NO with a 5 second breath hold, including the calculated outcomes Dm, Vc, and the D_L,NO/D_L,CO ratio, as well as to establish reference values for the outcomes of the traditional D_L,CO method, with a 10 second breath hold in children.

Methods

D_L,CO,NO and D_L,CO were measured in healthy children, of European descent, aged 5–17 years using a Jaeger Masterscreen PFT. The data were analyzed using the Generalized Additive Models for Location Scale and Shape (GAMLSS) statistical method.

Measurements and Main Results

A total of 326 children were eligible for diffusing capacity measurements, resulting in 312 measurements of D_L,CO,NO and 297 of D_L,CO, respectively. Reference equations were established for the outcomes of D_L,CO,NO and D_L,CO, including the calculated values: Vc, Dm, and the D_L,NO/D_L,CO ratio.

Conclusion

These reference values are based on the largest sample of children to date and may provide a basis for future studies of their clinical utility in differentiating between alterations in the pulmonary circulation and changes in the alveolar membrane in pediatric patients.     

Soybean leaf hydraulic conductance does not acclimate to growth at elevated [CO2] or temperature in growth chambers or in the field

Background and Aims

Leaf hydraulic properties are strongly linked with transpiration and photosynthesis in many species. However, it is not known if gas exchange and hydraulics will have co-ordinated responses to climate change. The objective of this study was to investigate the responses of leaf hydraulic conductance (K_leaf) in Glycine max (soybean) to growth at elevated [CO₂] and increased temperature compared with the responses of leaf gas exchange and leaf water status.

Methods

Two controlled-environment growth chamber experiments were conducted with soybean to measure K_leaf, stomatal conductance (g_s) and photosynthesis (A) during growth at elevated [CO₂] and temperature relative to ambient levels. These results were validated with field experiments on soybean grown under free-air elevated [CO₂] (FACE) and canopy warming.

Key results

In chamber studies, K_leaf did not acclimate to growth at elevated [CO₂], even though stomatal conductance decreased and photosynthesis increased. Growth at elevated temperature also did not affect K_leaf, although g_s and A showed significant but inconsistent decreases. The lack of response of K_leaf to growth at increased [CO₂] and temperature in chamber-grown plants was confirmed with field-grown soybean at a FACE facility.

Conclusions

Leaf hydraulic and leaf gas exchange responses to these two climate change factors were not strongly linked in soybean, although g_s responded to [CO₂] and increased temperature as previously reported. This differential behaviour could lead to an imbalance between hydraulic supply and transpiration demand under extreme environmental conditions likely to become more common as global climate continues to change.     

Comparative Proteomics Analysis of Placenta from Pregnant Women with Intrahepatic Cholestasis of Pregnancy

Introduction

Intrahepatic cholestasis of pregnancy (ICP) usually occurs in the third trimester and associated with increased risks in fetal complications. Currently, the exact cause of this disease is unknown. In this study we aim to investigate the potential proteins in placenta, which may participate in the molecular mechanisms of ICP-related fetal complications using iTRAQ-based proteomics approach.

Methods

The iTRAQ analysis combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was performed to separate differentially expressed placental proteins from 4 pregnant women with ICP and 4 healthy pregnant women. Bioinformatics analysis was used to find the relative processes that these differentially expressed proteins were involved in. Three apoptosis related proteins ERp29, PRDX6 and MPO that resulted from iTRAQ-based proteomics were further verified in placenta by Western blotting and immunohistochemistry. Placental apoptosis was also detected by TUNEL assay.

Results

Proteomics results showed there were 38 differentially expressed proteins from pregnant women with ICP and healthy pregnant women, 29 were upregulated and 9 were downregulated in placenta from pregnant women with ICP. Bioinformatics analysis showed most of the identified proteins was functionally related to specific cell processes, including apoptosis, oxidative stress, lipid metabolism. The expression levels of ERp29, PRDX6 and MPO were consistent with the proteomics data. The apoptosis index in placenta from ICP patients was significantly increased.

Conclusion

This preliminary work provides a better understanding of the proteomic alterations of placenta from pregnant women with ICP and may provide us some new insights into the pathophysiology and potential novel treatment targets for ICP.