Lymphatic function is regulated by a coordinated expression of lymphangiogenic and anti-lymphangiogenic cytokines

Lymphangiogenic cytokines such as vascular endothelial growth factor-C (VEGF-C) are critically required for lymphatic regeneration; however, in some circumstances, lymphatic function is impaired despite normal or elevated levels of these cytokines. The recent identification of anti-lymphangiogenic molecules such as interferon-γ (IFN-γ), transforming growth factor-β1, and endostatin has led us to hypothesize that impaired lymphatic function may represent a dysregulated balance in the expression of pro/anti-lymphangiogenic stimuli. We observed that nude mice have significantly improved lymphatic function compared with wild-type mice in a tail model of lymphedema. We show that gradients of lymphatic fluid stasis regulate the expression of lymphangiogenic cytokines (VEGF-A, VEGF-C, and hepatocyte growth factor) and that paradoxically the expression of these molecules is increased in wild-type mice. More importantly, we show that as a consequence of T-cell-mediated inflammation, these same gradients also regulate expression patterns of anti-lymphangiogenic molecules corresponding temporally and spatially with impaired lymphatic function in wild-type mice. We show that neutralization of IFN-γ significantly increases inflammatory lymph node lymphangiogenesis independently of changes in VEGF-A or VEGF-C expression, suggesting that alterations in the balance of pro- and anti-lymphangiogenic cytokine expression can regulate lymphatic vessel formation. In conclusion, we show that gradients of lymphatic fluid stasis regulate not only the expression of pro-lymphangiogenic cytokines but also potent suppressors of lymphangiogenesis as a consequence of T-cell inflammation and that modulation of the balance between these stimuli can regulate lymphatic function.     

Vascular endothelial growth factor (VEGF) +405 C/G polymorphism is associated with essential hypertension in a population from Tehran of Iran

Vascular endothelial growth factor (VEGF) has long been recognized as a hypotensive mediator. Little is known regarding the contribution of polymorphisms in VEGF gene to essential hypertension (EH), however. We aimed to investigate the association between +405 VEGF C/G single nucleotide polymorphism (SNP) and occurrence of EH in a sample of patients with diabetes. A study population of 474 subjects with diabetes of which 45.6% (216) had EH was enrolled in this study. Interviews and physical examinations were performed in a clinical setting. Subjects were matched in baseline anthropometric and biochemical characteristics except for total cholesterol. Genotyping of +405 VEGF C/G (rs2010963) SNP was carried out using polymerase chain reaction–restriction fragment length polymorphism. The allelic distribution of the sample did not violate Hardy–Weinberg equilibrium. Subjects with EH had a higher frequency of G allele (P = 0.005). Additionally, those with EH had a significantly higher frequency of GG genotype (P = 0.015). In multivariate logistic regression models controlling for possible confounders, having GG against CC genotype was associated with an odds ratio of 2.51 (95% CI: 1.44–4.38; P = 0.001). Moreover, presence of each G allele was linked to a 1.58-fold increase in risk of having EH (95% CI: 1.200–2.086; P = 0.001). In conclusion, +405 VEGF C/G SNP is associated with EH in patients with diabetes, suggesting presence of G allele and GG or CG genotype confer susceptibility towards EH.     

Effect of periplasmic expression of recombinant mouse interleukin-4 on hydrogen peroxide concentration and catalase activity in Escherichia coli

Oxidative stress occurs as a result of imbalance between generation and detoxification of reactive oxygen species (ROS). This kind of stress was rarely discussed in connection with foreign protein production in Escherichia coli. Relation between cytoplasmic recombinant protein expression with H₂O₂ concentration and catalase activity variation was already reported. The periplasmic space of E. coli has different oxidative environment in relative to cytoplasm and there are some benefits in periplasmic expression of recombinant proteins. In this study, hydrogen peroxide concentration and catalase activity following periplasmic expression of mouse IL-4 were measured in E. coli. After construction of pET2mIL4 plasmid, the expression of recombinant mouse interleukin-4 (mIL-4) was confirmed. Then, the H₂O₂ concentration and catalase activity variation in the cells were studied in exponential and stationary phases at various ODs and were compared to those of wild type cells and empty vector transformed cells. It was revealed that empty vector introduction and periplasmic recombinant protein expression increased significantly the H₂O₂ concentration of the cells. However, the H₂O₂ concentration in mIL-4 expressing cells was significantly higher than its concentration in empty vector transformed cells, demonstrating more effects of recombinant mIL-4 expression on H₂O₂ elevation. Likewise, although catalase activity was reduced in foreign DNA introduced cells, it was more lowered following expression of recombinant proteins. Correlation between H₂O₂ concentration elevation and catalase activity reduction with cell growth depletion is also demonstrated. It was also found that recombinant protein expression results in cell size increase.     

Cryosectioning Yeast Communities for Examining Fluorescence Patterns

Microbes typically live in communities. The spatial organization of cells within a community is believed to impact the survival and function of the community¹. Optical sectioning techniques, including confocal and two-photon microscopy, have proven useful for observing spatial organization of bacterial and archaeal communities^2,3. A combination of confocal imaging and physical sectioning of yeast colonies has revealed internal organization of cells⁴. However, direct optical sectioning using confocal or two-photon microscopy has been only able to reach a few cell layers deep into yeast colonies. This limitation is likely because of strong scattering of light from yeast cells⁴.Here, we present a method based on fixing and cryosectioning to obtain spatial distribution of fluorescent cells within Saccharomyces cerevisiae communities. We use methanol as the fixative agent to preserve the spatial distribution of cells. Fixed communities are infiltrated with OCT compound, frozen, and cryosectioned in a cryostat. Fluorescence imaging of the sections reveals the internal organization of fluorescent cells within the community.Examples of yeast communities consisting of strains expressing red and green fluorescent proteins demonstrate the potentials of the cryosectioning method to reveal the spatial distribution of fluorescent cells as well as that of gene expression within yeast colonies^2,3. Even though our focus has been on Saccharomyces cerevisiae communities, the same method can potentially be applied to examine other microbial communities.     

Estimation of trunk mechanical properties using system identification: effects of experimental setup and modelling assumptions

The use of system identification to quantify trunk mechanical properties is growing in biomechanics research. The effects of several experimental and modelling factors involved in the system identification of trunk mechanical properties were investigated. Trunk kinematics and kinetics were measured in six individuals when exposed to sudden trunk perturbations. Effects of motion sensor positioning and properties of elements between the perturbing device and the trunk were investigated by adopting different models for system identification. Results showed that by measuring trunk kinematics at a location other than the trunk surface, the deformation of soft tissues is erroneously included into trunk kinematics and results in the trunk being predicted as a more damped structure. Results also showed that including elements between the trunk and the perturbing device in the system identification model did not substantially alter model predictions. Other important parameters that were found to substantially affect predictions were the cut-off frequency used when low-pass filtering raw data and the data window length used to estimate trunk properties.     

Binding of divalent metal ions to calcium-free peroxidase: thermodynamic and kinetic studies

Thermodynamics of binding of divalent metal ions including Ca(2+) , Mg(2+) , Ba(2+) , and Cd(2+) to Ca-free horseradish peroxidase (HRP) enzyme was investigated using UV/VIS spectrophotometry and molecular-mechanic (MM) calculations. According to the obtained binding and thermodynamic parameters, trend of the relative binding affinities of these divalent metal cations was found to be: Ca(2+) >Cd(2+) >Mg(2+) >Ba(2+) . Binding analysis based on Scatchard and Hill models showed positive cooperativity effect between the two distal and proximal binding sites. Furthermore, kinetics of binding and reconstitution process was examined (using relaxation-time method) for binding of Ca(2+) (as the typical metal ion) to Ca-free HRP, which was found a second-order type having a two-step mechanism involving fast formation of Ca-free HRP/1?Ca(2+) as the kinetic intermediate in step 1. Finally, by means of MM calculations, the comparative stability energies were evaluated for binding of M(2+) metal cations to Ca-free HRP. Based on MM calculations, preferential binding of Ca(2+) ion was occurred on distal and proximal binding sites of Ca-free HRP associated with higher stability energies (E(total) ). Indeed, among the divalent metal ions, Ca(2+) with the highest binding affinity (maximum value of K(bin) and minimum value of ΔG$\rm{{_{bin}^{0}}}$), maximum value of exothermic binding enthalpy, and stability energies stabilizes the HRP structure along with an optimized catalytic activity.     

Carbonized Chicken Eggshell Membranes with 3D Architectures as High‐Performance Electrode Materials for Supercapacitors

Supercapacitor electrode materials are synthesized by carbonizing a common livestock biowaste in the form of chicken eggshell membranes. The carbonized eggshell membrane (CESM) is a three‐dimensional macroporous carbon film composed of interwoven connected carbon fibers containing around 10 wt% oxygen and 8 wt% nitrogen. Despite a relatively low surface area of 221 m² g^?1, exceptional specific capacitances of 297 F g^?1 and 284 F g^?1 are achieved in basic and acidic electrolytes, respectively, in a 3‐electrode system. Furthermore, the electrodes demonstrate excellent cycling stability: only 3% capacitance fading is observed after 10 000 cycles at a current density of 4 A g^?1. These very attractive electrochemical properties are discussed in the context of the unique structure and chemistry of the material.