Sugar-stimulated CO2 sequestration by the green microalga Chlorella vulgaris

To convert waste CO₂ from flue gases of power plants into value-added products, bio-mitigation technologies show promise. In this study, we cultivated a fast-growing species of green microalgae, Chlorella vulgaris, in different sizes of photobioreactors (PBRs) and developed a strategy using small doses of sugars for enhancing CO₂ sequestration under light-emitting diode illumination. Glucose supplementation at low levels resulted in an increase of photoautotrophic growth-driven biomass generation as well as CO₂ capture by 10% and its enhancement corresponded to an increase of supplied photon flux. The utilization of urea instead of nitrate as the sole nitrogen source increased photoautotrophic growth by 14%, but change of nitrogen source didn't compromise glucose-induced enhancement of photoautotrophic growth. The optimized biomass productivity achieved was 30.4% higher than the initial productivity of purely photoautotrophic culture. The major pigments in the obtained algal biomass were found comparable to its photoautotrophic counterpart and a high neutral lipids productivity of 516.6 mg/(L·day) was achieved after optimization. A techno-economic model was also developed, indicating that LED-based PBRs represent a feasible strategy for converting CO₂ into value-added algal biomass.

Dataset on economic analysis of mass production of algae in LED-based photobioreactors

The data presented in this article are related to the research article entitled "Sugar-stimulated CO₂ sequestration by the green microalga Chlorella vulgaris" (Fu et al., 2019) [1]. The data describe a rational design and scale-up of LED-based photobioreactors for producing value-added algal biomass while removing waste CO₂ from flu gases from power plants. The dataset were created from growth rate experiments for biomass production including direct biomass productivity data, PBR size and setup parameters, medium composition as well as indirect energy cost and overhead in Iceland. A complete economic analysis is formed through a cost breakdown as well as PBR scalability predictions.

Metabolic systems analysis of LPS induced endothelial dysfunction applied to sepsis patient stratification

Endothelial dysfunction contributes to sepsis outcome. Metabolic phenotypes associated with endothelial dysfunction are not well characterised in part due to difficulties in assessing endothelial metabolism in situ. Here, we describe the construction of iEC2812, a genome scale metabolic reconstruction of endothelial cells and its application to describe metabolic changes that occur following endothelial dysfunction. Metabolic gene expression analysis of three endothelial subtypes using iEC2812 suggested their similar metabolism in culture. To mimic endothelial dysfunction, an in vitro sepsis endothelial cell culture model was established and the metabotypes associated with increased endothelial permeability and glycocalyx loss after inflammatory stimuli were quantitatively defined through metabolomics. These data and transcriptomic data were then used to parametrize iEC2812 and investigate the metabotypes of endothelial dysfunction. Glycan production and increased fatty acid metabolism accompany increased glycocalyx shedding and endothelial permeability after inflammatory stimulation. iEC2812 was then used to analyse sepsis patient plasma metabolome profiles and predict changes to endothelial derived biomarkers. These analyses revealed increased changes in glycan metabolism in sepsis non-survivors corresponding to metabolism of endothelial dysfunction in culture. The results show concordance between endothelial health and sepsis survival in particular between endothelial cell metabolism and the plasma metabolome in patients with sepsis.

Quantitative time-course metabolomics in human red blood cells reveal the temperature dependence of human metabolic networks

The temperature dependence of biological processes has been studied at the levels of individual biochemical reactions and organism physiology (e.g. basal metabolic rates) but has not been examined at the metabolic network level. Here, we used a systems biology approach to characterize the temperature dependence of the human red blood cell (RBC) metabolic network between 4 and 37 °C through absolutely quantified exo- and endometabolomics data. We used an Arrhenius-type model (Q₁₀) to describe how the rate of a biochemical process changes with every 10 °C change in temperature. Multivariate statistical analysis of the metabolomics data revealed that the same metabolic network-level trends previously reported for RBCs at 4 °C were conserved but accelerated with increasing temperature. We calculated a median Q₁₀ coefficient of 2.89 ± 1.03, within the expected range of 2-3 for biological processes, for 48 individual metabolite concentrations. We then integrated these metabolomics measurements into a cell-scale metabolic model to study pathway usage, calculating a median Q₁₀ coefficient of 2.73 ± 0.75 for 35 reaction fluxes. The relative fluxes through glycolysis and nucleotide metabolism pathways were consistent across the studied temperature range despite the non-uniform distributions of Q₁₀ coefficients of individual metabolites and reaction fluxes. Together, these results indicate that the rate of change of network-level responses to temperature differences in RBC metabolism is consistent between 4 and 37 °C. More broadly, we provide a baseline characterization of a biochemical network given no transcriptional or translational regulation that can be used to explore the temperature dependence of metabolism.

Metabolomics comparison of red cells stored in four additive solutions reveals differences in citrate anticoagulant permeability and metabolism

BACKGROUND AND OBJECTIVES

Metabolomics studies have revealed transition points in metabolic signatures of red cells during storage in SAGM, whose clinical significance is unclear. We set out to investigate whether these transition points occur independent of storage media and define differences in the metabolism of red cells in additive solutions.

MATERIALS AND METHODS

Red cell concentrates were stored in SAGM, AS-1, AS-3 or PAGGSM, and sampled fourteen times spanning Day 1-46. Following quality control, the samples were split into extracellular and intracellular aliquots. These were analysed with ultra-high-performance liquid chromatography coupled to mass spectrometry analysis affording quantitative metabolic profiles of both intra- and extracellular red cell metabolites.

RESULTS

Differences were observed in glycolysis, purine salvage, glutathione synthesis and citrate metabolism on account of the storage solutions. Donor variability however hindered the accurate characterization of metabolic transition time-points. Intracellular citrate concentrations were increased in red cells stored in AS-3 and PAGGSM media. The metabolism of citrate in red cells in SAGM was subsequently confirmed using ¹³ C citrate isotope labelling and shown to originate from citrate anticoagulant.

CONCLUSION

Metabolic signatures that discriminate between 'fresh' and 'old' stored red cells are dependent upon additive solutions. Specifically, the incorporation and metabolism of citrate in additive solutions with lower chloride ion concentration is altered and impacts glycolysis.

Metabolic fate of adenine in red blood cells during storage in SAGM solution

BACKGROUND

Red blood cells (RBCs) are routinely stored and transfused worldwide. Recently, metabolomics have shown that RBCs experience a three-phase metabolic decay process during storage, resulting in the definition of three distinct metabolic phenotypes, occurring between Days 1 and 10, 11 and 17, and 18 and 46. Here we use metabolomics and stable isotope labeling analysis to study adenine metabolism in RBCs.

STUDY DESIGN AND METHODS

A total of 6 units were prepared in SAGM or modified additive solutions (ASs) containing ¹⁵ N₅ -adenine. Three of them were spiked with ¹⁵ N₅ -adenine on Days 10, 14, and 17 during storage. Each unit was sampled 10 times spanning Day 1 to Day 32. At each time point metabolic profiling was performed.

RESULTS

We increased adenine concentration in the AS and we pulsed the adenine concentration during storage and found that in both cases the RBCs' main metabolic pathways were not affected. Our data clearly show that RBCs cannot consume adenine after 18 days of storage, even if it is still present in the storage solution. However, increased levels of adenine influenced S-adenosylmethionine metabolism.

CONCLUSION

In this work, we have studied in detail the metabolic fate of adenine during RBC storage in SAGM. Adenine is one of the main substrates used by RBCs, but the metabolic shift observed during storage is not caused by an absence of adenine later in storage. The rate of adenine consumption strongly correlated with duration of storage but not with the amount of adenine present in the AS.

Understanding the Causes and Implications of Endothelial Metabolic Variation in Cardiovascular Disease through Genome-Scale Metabolic Modeling

High-throughput biochemical profiling has led to a requirement for advanced data interpretation techniques capable of integrating the analysis of gene, protein, and metabolic profiles to shed light on genotype-phenotype relationships. Herein, we consider the current state of knowledge of endothelial cell (EC) metabolism and its connections to cardiovascular disease (CVD) and explore the use of genome-scale metabolic models (GEMs) for integrating metabolic and genomic data. GEMs combine gene expression and metabolic data acting as frameworks for their analysis and, ultimately, afford mechanistic understanding of how genetic variation impacts metabolism. We demonstrate how GEMs can be used to investigate CVD-related genetic variation, drug resistance mechanisms, and novel metabolic pathways in ECs. The application of GEMs in personalized medicine is also highlighted. Particularly, we focus on the potential of GEMs to identify metabolic biomarkers of endothelial dysfunction and to discover methods of stratifying treatments for CVDs based on individual genetic markers. Recent advances in systems biology methodology, and how these methodologies can be applied to understand EC metabolism in both health and disease, are thus highlighted.

Identified metabolic signature for assessing red blood cell unit quality is associated with endothelial damage markers and clinical outcomes

BACKGROUND

There has been interest in determining whether older red blood cell (RBC) units have negative clinical effects. Numerous observational studies have shown that older RBC units are an independent factor for patient mortality. However, recently published randomized clinical trials have shown no difference of clinical outcome for patients receiving old or fresh RBCs. An overlooked but essential issue in assessing RBC unit quality and ultimately designing the necessary clinical trials is a metric for what constitutes an old or fresh RBC unit.

STUDY DESIGN AND METHODS

Twenty RBC units were profiled using quantitative metabolomics over 42 days of storage in SAGM with 3- to 4-day time intervals. Metabolic pathway usage during storage was assessed using systems biology methods. The detected time intervals of the metabolic states were compared to clinical outcomes.

RESULTS

Using multivariate statistics, we identified a nonlinear decay process exhibiting three distinct metabolic states (Days 0-10, 10-17, and 17-42). Hematologic variables traditionally measured in the transfusion setting (e.g., pH, hemolysis, RBC indices) did not distinguish these three states. Systemic changes in pathway usage occurred between the three states, with key pathways changing in both magnitude and direction. Finally, an association was found between the time periods of the metabolic states with the clinical outcomes of more than 280,000 patients in the country of Denmark transfused over the past 15 years and endothelial damage markers in healthy volunteers undergoing autologous transfusions.

CONCLUSION

The state of RBC metabolism may be a better indicator of cellular quality than traditional hematologic variables.

The development of a fully-integrated immune response model (FIRM) simulator of the immune response through integration of multiple subset models

Background

The complexity and multiscale nature of the mammalian immune response provides an excellent test bed for the potential of mathematical modeling and simulation to facilitate mechanistic understanding. Historically, mathematical models of the immune response focused on subsets of the immune system and/or specific aspects of the response. Mathematical models have been developed for the humoral side of the immune response, or for the cellular side, or for cytokine kinetics, but rarely have they been proposed to encompass the overall system complexity. We propose here a framework for integration of subset models, based on a system biology approach.

Results

A dynamic simulator, the Fully-integrated Immune Response Model (FIRM), was built in a stepwise fashion by integrating published subset models and adding novel features. The approach used to build the model includes the formulation of the network of interacting species and the subsequent introduction of rate laws to describe each biological process. The resulting model represents a multi-organ structure, comprised of the target organ where the immune response takes place, circulating blood, lymphoid T, and lymphoid B tissue. The cell types accounted for include macrophages, a few T-cell lineages (cytotoxic, regulatory, helper 1, and helper 2), and B-cell activation to plasma cells. Four different cytokines were accounted for: IFN-γ, IL-4, IL-10 and IL-12. In addition, generic inflammatory signals are used to represent the kinetics of IL-1, IL-2, and TGF-β. Cell recruitment, differentiation, replication, apoptosis and migration are described as appropriate for the different cell types. The model is a hybrid structure containing information from several mammalian species. The structure of the network was built to be physiologically and biochemically consistent. Rate laws for all the cellular fate processes, growth factor production rates and half-lives, together with antibody production rates and half-lives, are provided. The results demonstrate how this framework can be used to integrate mathematical models of the immune response from several published sources and describe qualitative predictions of global immune system response arising from the integrated, hybrid model. In addition, we show how the model can be expanded to include novel biological findings. Case studies were carried out to simulate TB infection, tumor rejection, response to a blood borne pathogen and the consequences of accounting for regulatory T-cells.

Conclusions

The final result of this work is a postulated and increasingly comprehensive representation of the mammalian immune system, based on physiological knowledge and susceptible to further experimental testing and validation. We believe that the integrated nature of FIRM has the potential to simulate a range of responses under a variety of conditions, from modeling of immune responses after tuberculosis (TB) infection to tumor formation in tissues. FIRM also has the flexibility to be expanded to include both complex and novel immunological response features as our knowledge of the immune system advances.

Performance of the SF-36 Health Survey in screening for depressive and anxiety disorders in an elderly female Swedish population

OBJECTIVE

To assess the sensitivity, specificity and predictive validity of suggested cut-off scores in the SF-36 mental health (MH) and mental component summary (MCS) in screening for depressive and anxiety disorders in a population sample of older Swedish women.

METHOD

The sample comprised 586 randomly selected females aged 70-84 years who took part in an in-depth psychiatric examination. This provided the 'gold standard' against which the usefulness of SF-36 recommended thresholds for screening for depressive and anxiety disorders in older Swedish women was examined.

RESULTS

Based on DSM-III-R criteria, 69 women (12%) were diagnosed with depression (major depression, dysthymia and/or depression NOS) and 49 (8%) with generalised anxiety and panic disorders. The previously recommended MH and MCS cut-offs (i.e. 52 and 42) gave a specificity for diagnosis of depression of 92 and 82% and sensitivity of 58 and 71%, respectively. Both the MH and MCS were good predictors of depressive disorders but poor predictors of anxiety disorders.

CONCLUSION

The study supports the predictive validity of suggested SF-36 MH and MCS cut-off scores in screening for depressive disorder but not for anxiety disorder in older women in Sweden.

Extensive sharing of chloroplast haplotypes among European birches indicates hybridization among Betula pendula, B. pubescens and B. nana

Extensive sharing of chloroplast haplotypes among the silver birch, Betula pendula Roth., the downy birch, B. pubescens Ehrh., and the dwarf birch, B. nana L., was discovered using polymerase chain reaction-restriction fragment length polymporphism markers. The geographical component of the genetic variation was stronger than the species component: the species were not significantly different while 11% of the variation could be attributed to differentiation between the two main regions studied, Scandinavia and western Russia. All haplotypes occurring in more than 2% of the individuals were shared among the species and the introgression ratios were quite large: 0.79 between B. pubescens and B. pendula and 0.67 between B. pubescens and B. nana. The data also indicate that B. pendula individuals are more similar to sympatric B. pubescens than to B. pendula individuals from nearby forests. However, this trend is not as pronounced when B. pubescens is considered, suggesting that introgression is not symmetrical. The haplotype sharing among the three Betula species is most likely caused by hybridization and subsequent cytoplasmic introgression.

A population-based study on brain atrophy and motor performance in elderly women

BACKGROUND

Brain atrophy is a common neuroimaging finding in healthy elderly individuals as well as in patients with movement-related disorders. The relationship between brain atrophy and motor changes has not been frequently reported. This study investigates this relationship.

METHODS

A population-based sample of women (N = 238), aged 70, 74, and 78 years, living in Göteborg, Sweden, participated in this study. Motor performance was measured by a laboratory test, the Postural-Locomotion-Manual test, which precisely measures the subject's mobility of lower and upper extremities using an optoelectronic technique. Cortical and central atrophy were rated on computerized tomographic (CT) scans of the brain.

RESULTS

In bivariate analysis, temporal lobe atrophy, high sylvian fissure ratio, and high bicaudate ratio were correlated with impaired mobility. The association between temporal lobe atrophy and high sylvian fissure ratio and poor mobility remained after controlling for age, smoking, coronary heart disease, diabetes mellitus, hypertension, and white matter lesions on CT scans.

CONCLUSIONS

Our results suggest that temporal lobe atrophy, which is often seen on brain imaging in elderly persons, might be an important brain abnormality related to motor impairments in elderly women. Further studies to investigate this relationship and its underlying mechanisms are needed.

A population-based study on motor performance and white matter lesions in older women

OBJECTIVE

To investigate the relationship between motor performance and white matter lesions (WMLs) on computed tomography (CT) of the brain in older women.

DESIGN

Cross-sectional study.

SETTING

Population-based study in Göteborg, Sweden.

PARTICIPANTS

A total of 248 women aged 70, 74, and 78 years.

MEASUREMENTS

Motor performance was measured by a Postural-Locomotion-Manual (PLM) test using an optoelectronic technique. WMLs on CT scans were rated as no, mild, moderate, or severe.

RESULTS

White matter lesions were associated with impaired mobility of the lower extremities, that is, prolonged locomotion phase in the PLM test. This association was also present after controlling for age, hypertension, coronary heart disease, stroke, diabetes mellitus, chronic bronchitis, intermittent claudication, and smoking.

CONCLUSIONS

Cerebral white matter lesions may contribute to motor impairments in older adults.

The epidemiology of affective disorders in the elderly: a review

It has been suggested that elderly people are predisposed to depression by age-related structural and biochemical changes that may increase their vulnerability to depression and by the fact that risk factors such as bereavement and other psychological losses, somatic diseases and institutionalization become more common with increasing age. The elderly also have a disproportionately high rate of suicide. Whether the prevalence of depression increases or decreases with age is, however, debatable. There may be a peak in the prevalence during the years before retirement, a low prevalence during the first 10-15 years thereafter, and an increase after the age of 75 years. Among the consequences of depression are social deprivation, loneliness, poor quality of life, increased use of health and home-care services, cognitive decline, impairments in activities of daily living, chronicity, suicide and increased non-suicide mortality. However, most studies report that few depressives in the community are treated with antidepressants. During recent years new antidepressants have been introduced, which are better tolerated by the elderly. At the same time, the prescription of anti-depressants has increased in the community. It remains to be seen whether these changes have led to a higher rate of treatment of depression in the elderly.

Suicidal feelings in a population sample of nondemented 85-year-olds

OBJECTIVE

The authors studied the 1-month frequency of suicidal feelings among very old people.

METHOD

A population sample (N = 345) of nondemented 85-year-olds in Gothenburg, Sweden, were examined by a psychiatrist. Suicidal feelings were rated by the system of Paykel et al. Mental disorders were diagnosed according to DSM-III-R.

RESULTS

Of the mentally healthy subjects (N = 225), 4.0% had thought during the last month that life was not worth living, 4.0% had had death wishes, and 0.9% had thought of taking their own lives. None had seriously considered suicide. The figures were higher among subjects with mental disorders (N = 120); 29.2% had thought that life was not worth living, 27.5% had had death wishes, 9.2% had thought about taking their lives, and 1.7% had seriously considered suicide. Among the subjects with mental disorders, including depression, suicidal feelings were associated with greater use of anxiolytics but not of antidepressants. Women who felt that life was not worth living had a higher 3-year mortality rate than did women without these feelings (43.2% versus 14.2%). This finding was independent of concomitant physical and mental disorders.

CONCLUSIONS

Mild suicidal feelings are common in elderly subjects with metal disorders but infrequent in the mentally healthy. The substantially higher mortality rate in women who felt that life was not worth living, compared to women who did not, suggests these feelings must be taken seriously. Because of the high suicide rate in the elderly, there is a need for better diagnosis and treatment of mental disorders in this age group.