Synthetic Lethality in the Tobacco Plastid Ribosome and Its Rescue at Elevated Growth Temperatures

Consistent with their origin from cyanobacteria, plastids (chloroplasts) perform protein biosynthesis on bacterial-type 70S ribosomes. The plastid genomes of seed plants contain a conserved set of ribosomal protein genes. Three of these have proven to be nonessential for translation and, thus, for cellular viability: rps15, rpl33, and rpl36. To help define the minimum ribosome, here, we examined whether more than one of these nonessential plastid ribosomal proteins can be removed from the 70S ribosome. To that end, we constructed all possible double knockouts for the S15, L33, and L36 ribosomal proteins by stable transformation of the tobacco (Nicotiana tabacum) plastid genome. We find that, although S15 and L33 function in different ribosomal particles (30S and 50S, respectively), their combined deletion from the plastid genome results in synthetic lethality under autotrophic conditions. Interestingly, the lethality can be overcome by growth under elevated temperatures due to an improved efficiency of plastid ribosome biogenesis. Our results reveal functional interactions between protein and RNA components of the 70S ribosome and uncover the interdependence of the biogenesis of the two ribosomal subunits. In addition, our findings suggest that defining a minimal set of plastid genes may prove more complex than generally believed.     

Phenylcoumaran Benzylic Ether Reductase Prevents Accumulation of Compounds Formed under Oxidative Conditions in Poplar Xylem

Phenylcoumaran benzylic ether reductase (PCBER) is one of the most abundant proteins in poplar (Populus spp) xylem, but its biological role has remained obscure. In this work, metabolite profiling of transgenic poplar trees downregulated in PCBER revealed both the in vivo substrate and product of PCBER. Based on mass spectrometry and NMR data, the substrate was identified as a hexosylated 8–5-coupling product between sinapyl alcohol and guaiacylglycerol, and the product was identified as its benzyl-reduced form. This activity was confirmed in vitro using a purified recombinant PCBER expressed in Escherichia coli. Assays performed on 20 synthetic substrate analogs revealed the enzyme specificity. In addition, the xylem of PCBER-downregulated trees accumulated over 2000-fold higher levels of cysteine adducts of monolignol dimers. These compounds could be generated in vitro by simple oxidative coupling assays involving monolignols and cysteine. Altogether, our data suggest that the function of PCBER is to reduce phenylpropanoid dimers in planta to form antioxidants that protect the plant against oxidative damage. In addition to describing the catalytic activity of one of the most abundant enzymes in wood, we provide experimental evidence for the antioxidant role of a phenylpropanoid coupling product in planta.     

Chronic obstructive pulmonary disease (COPD): Evaluation from clinical,immunological and bacterial pathogenesis perspectives

Chronic obstructive pulmonary disease (COPD), a disease manifested by significantly impaired airflow, afflicts ～14.2 million cases in the United States alone with an estimated 63 million people world-wide. Although there are a number of causes, the predominant cause is excessive tobacco smoke. In fact, in China, there have been estimates of 315,000,000 people that smoke. Other less frequent causes are associated with indirect cigarette smoke, air pollutants, biomass fuels, and genetic mutations. COPD is often associated with heart disease, lung cancer, osteoporosis and conditions can worsen in patients with sudden falls. COPD also affects both innate and adaptive immune processes. Cigarette smoke increases the expression of matrix metalloproteases and proinflammatory chemokines and increases lung titers of natural killer cells and neutrophils. Yet, neutrophil reactive oxygen species (ROS) mediated by the phagocytic respiratory burst and phagocytosis is impaired by nicotine. In contrast to innate immunity in COPD, dendritic cells represent leukocytes recruited to the lung that link the innate immune responses to adaptive immune responses by activating naïve T cells through antigen presentation. The autoimmune process that is also a significant part of inflammation associated with COPD. Moreover, coupled with restricted FEV1 values, are the prevalence of patients with single or multiple infections by bacteria, viruses and fungi. Finally, we focus on one of the more problematic infectious agents, the Gram-negative opportunistic pathogenic bacterium, Pseudomonas aeruginosa. Specifically, we delve into the development of highly problematic biofilm infections that are highly refractory to conventional antibiotic therapies in COPD. We offer a non-conventional, biocidal treatment that may be effective for COPD airway infections as well as with combinations of current antibiotic regimens for more effective treatment outcomes and relief for patients with COPD.     

Characterization of Blockade Antibody Responses in GII.2.1976 Snow Mountain Virus-Infected Subjects

Snow Mountain virus (GII.2.1976) is the prototype strain of GII.2 noroviruses (NoVs), which cause an estimated 8% of norovirus outbreaks, yet little is known about the immunobiology of these viruses. To define the human immune response induced by SMV infection and the antigenic relationship between different GII.2 strains that have circulated between 1976 and 2010, we developed a panel of four GII.2 variant virus-like particles (VLPs) and compared their antigenicities by enzyme immunoassay (EIA) and surrogate antibody neutralization (blockade) assays. Volunteers infected with GII.2.1976 developed a mean 167-fold increase in blockade response against the homotypic VLP by day 8 postchallenge. Blockade extended cross-genotype activity in some individuals but not cross-genogroup activity. Polyclonal sera from GII.2.1976-infected volunteers blocked GII.2.1976 significantly better than they blocked GII.2.2002, GII.2.2008, and GII.2.2010, suggesting that blockade epitopes within the GII.2 strains have evolved in the past decade. To potentially map these epitope changes, we developed mouse monoclonal antibodies (MAbs) against GII.2.1976 VLPs and compared their reactivities to a panel of norovirus VLPs. One MAb had broad cross-genogroup EIA reactivity to a nonblockade, linear, conserved epitope. Six MAbs recognized conformational epitopes exclusive to the GII.2 strains. Two MAbs recognized GII.2 blockade epitopes, and both blocked the entire panel of GII.2 variants. These data indicate that the GII.2 strains, unlike the predominant GII.4 strains, have undergone only a limited amount of evolution in blockade epitopes between 1976 and 2010 and indicate that the GII.2-protective component of a multivalent norovirus vaccine may not require frequent reformulation.     

Traits and phylogenetic history contribute to network structure across Canadian plant–pollinator communities

Interaction webs, or networks, define how the members of two or more trophic levels interact. However, the traits that mediate network structure have not been widely investigated. Generally, the mechanism that determines plant-pollinator partnerships is thought to involve the matching of a suite of species traits (such as abundance, phenology, morphology) between trophic levels. These traits are often unknown or hard to measure, but may reflect phylogenetic history. We asked whether morphological traits or phylogenetic history were more important in mediating network structure in mutualistic plant-pollinator interaction networks from Western Canada. At the plant species level, sexual system, growth form, and flower symmetry were the most important traits. For example species with radially symmetrical flowers had more connections within their modules (a subset of species that interact more among one another than outside of the module) than species with bilaterally symmetrical flowers. At the pollinator species level, social species had more connections within and among modules. In addition, larger pollinators tended to be more specialized. As traits mediate interactions and have a phylogenetic signal, we found that phylogenetically close species tend to interact with a similar set of species. At the network level, patterns were weak, but we found increasing functional trait and phylogenetic diversity of plants associated with increased weighted nestedness. These results provide evidence that both specific traits and phylogenetic history can contribute to the nature of mutualistic interactions within networks, but they explain less variation between networks.     

Hyperferritinaemia in Dengue Virus Infected Patients Is Associated with Immune Activation and Coagulation Disturbances

Background

During a dengue outbreak on the Caribbean island Aruba, highly elevated levels of ferritin were detected in dengue virus infected patients. Ferritin is an acute-phase reactant and hyperferritinaemia is a hallmark of diseases caused by extensive immune activation, such as haemophagocytic lymphohistiocytosis. The aim of this study was to investigate whether hyperferritinaemia in dengue patients was associated with clinical markers of extensive immune activation and coagulation disturbances.

Methodology/Principal Findings

Levels of ferritin, standard laboratory markers, sIL-2R, IL-18 and coagulation and fibrinolytic markers were determined in samples from patients with uncomplicated dengue in Aruba. Levels of ferritin were significantly increased in dengue patients compared to patients with other febrile illnesses. Moreover, levels of ferritin associated significantly with the occurrence of viraemia. Hyperferritinaemia was also significantly associated with thrombocytopenia, elevated liver enzymes and coagulation disturbances. The results were validated in a cohort of dengue virus infected patients in Brazil. In this cohort levels of ferritin and cytokine profiles were determined. Increased levels of ferritin in dengue virus infected patients in Brazil were associated with disease severity and a pro-inflammatory cytokine profile.

Conclusions/Significance

Altogether, we provide evidence that ferritin can be used as a clinical marker to discriminate between dengue and other febrile illnesses. The occurrence of hyperferritinaemia in dengue virus infected patients is indicative for highly active disease resulting in immune activation and coagulation disturbances. Therefore, we recommend that patients with hyperferritinaemia are monitored carefully.     

The Charlson Comorbidity Index Can Be Used Prospectively to Identify Patients Who Will Incur High Future Costs

Background

Reducing health care costs requires the ability to identify patients most likely to incur high costs. Our objective was to evaluate the ability of the Charlson comorbidity score to predict the individuals who would incur high costs in the subsequent year and to contrast its predictive ability with other commonly used predictors.

Methods

We contrasted the prior year Charlson comorbidity index, costs, Diagnostic Cost Group (DCG) and hospitalization as predictors of subsequent year costs from claims data of fund that provides comprehensive health benefits to a large union of health care workers. Total costs in the subsequent year was the principal outcome.

Results

Of the 181,764 predominantly Black and Latino beneficiaries, 70% were adults (mean age 45.7 years; 62% women). As the comorbidity index increased, total yearly costs increased significantly (P<.001). At lower comorbidity, the costs were similar across different chronic diseases. Using regression to predict total costs, top 5^th and 10^th percentile of costs, the comorbidity index, prior costs and DCG achieved almost identical explained variance in both adults and children.

Conclusions and Relevance

The comorbidity index predicted health costs in the subsequent year, performing as well as prior cost and DCG in identifying those in the top 5% or 10%. The comorbidity index can be used prospectively to identify patients who are likely to incur high costs.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01761253","term_id":"NCT01761253"}}NCT01761253     

Epicardial Adipose Tissue Thickness Correlates with the Presence and Severity of Angiographic Coronary Artery Disease in Stable Patients with Chest Pain

Objective

Epicardial adipose tissue (EAT) is suggested to correlate with metabolic risk factors and to promote plaque development in the coronary arteries. We sought to determine whether EAT thickness was associated or not with the presence and extent of angiographic coronary artery disease (CAD).

Methods

We measured epicardial fat thickness by computed tomography and assessed the presence and extent of CAD by coronary angiography in participants from the prospective EVASCAN study. The association of EAT thickness with cardiovascular risk factors, coronary artery calcification scoring and angiographic CAD was assessed using multivariate regression analysis.

Results

Of 970 patients (age 60.9 years, 71% male), 75% (n = 731) had CAD. Patients with angiographic CAD had thicker EAT on the left ventricle lateral wall when compared with patients without CAD (2.74±2.4 mm vs. 2.08±2.1 mm; p = 0.0001). The adjusted odds ratio (OR) for a patient with a LVLW EAT value ≥2.8 mm to have CAD was OR = 1.46 [1.03–2.08], p = 0.0326 after adjusting for risk factors. EAT also correlated with the number of diseased vessels (p = 0.0001 for trend). By receiver operating characteristic curve analysis, an EAT value ≥2.8 mm best predicted the presence of>50% diameter coronary artery stenosis, with a sensitivity and specificity of 46.1% and 66.5% respectively (AUC:0.58). Coronary artery calcium scoring had an AUC of 0.76.

Conclusion

Although left ventricle lateral wall EAT thickness correlated with the presence and extent of angiographic CAD, it has a low performance for the diagnosis of CAD.