Production and Decomposition of Hydrogen Peroxide by Marine Phytoplankton

H202 in seawater has complicated sources and sinks. The relative importance of biological regulation of H202 compared to other processes is not well understood. In addition, environmental factors affecting the biological regulation of H202 are largely unknown. Marine phytoplankton was examined for the kinetics of the production and decomposition of H202 in the dark. Effects of varying environmental factors such as light, temperature, salinity, nutrients, amino acids, trace metals and growth phase, were examined. H202 was determined with the scopoletin-fluorescence decay method. Five out of 11 species produced H202, while all of the 11 species decomposed H202. The relative significance of these species for producing H202 decreased in the order of Pleurochrysis carterae \u3e Isochrysis galbana \u3e Dunaliella tertiolecta \u3e Tetraselmis levis \u3e Emiliania huxleyi, and for decomposing it in the order of Synechococcus sp. = Skeletonema costatum » Tetraselmis levis \u3e Chaetoceros flexosus \u3e Chaetoceros simplex \u3e Isochrysis galbana \u3e Thalassiosira oceanica \u3e Amphidinium carterae \u3e Pleurochrysis carterae \u3e Emiliania huxleyi \u3e Dunaliella tertiolecta. Coccoid or unialgal cells showed a tendency to produce H202, whereas diatoms in chains were more likely to decompose H202. Both the production and decomposition of H202 by these algae followed pseudo-first order reactions. The pseudo-first order rate constants related linearly to algal biomass. The biologically-mediated production and decomposition of H202 showed reaction rate constants (k) ranging from 0.0017 to 0.0072 (fig chl-a\u27L\u27^ ^hr\u271 for the production of H202 and from 0.0242 to 0.0002 (μg chl-a •L\u271)\u27hr\u271 for the decomposition of H202. The studies on the rate kinetics suggested that marine phytoplankton regulates the H202 budget in surface oceans by mediating primarily decomposition of H202 rather than production of H202. The biological regulation of H202 was not strongly affected by physical environmental factors such as light, temperature and salinity. Among the tested factors, amino acids were the most influential factor enhancing the production of H202. Inorganic nitrogen-limited conditions stimulated phytoplankton to produce more H202 per unit biomass. The production of H202 may be a result of amino acid utilization by nitrogen-starved phytoplankton. However, decomposition of H202 was not affected by the addition of amino acids. Nutrient effects on the decomposition rate constants were much more profound in coastal species than in oligotrophic species. In general, the biological production of H202 was small compared to photochemical production but could be significant in nitrogen-limited conditions whereas biological decomposition of H202 was more important than other removal processes. The results of pure culture studies generally agreed with the results of the field studies. The oligotrophic Sargasso seawater showed biological production of H202 whereas the mesotrophic coastal water displayed predominantly decomposition of H202. Biological production of H202 could occur mostly in inorganic nitrogen-limited conditions by a limited number of species whereas biological decomposition of H202 could remove H202 from most coastal waters by a large number of species. This study implied that nitrogen dynamics as well as phytoplankton species composition and their abundance are necessary to understand biological roles in H202 budget. The regulation of H202 by phytoplankton may also be related to the speciation of trace metals in ambient waters because of strong oxidizing/reducing properties of H202

Cyclooxygenase-2 and p53 Expression as Prognostic Indicators in Conventional Renal Cell Carcinoma

The aim of this study was to investigate the relationship of cyclooxygenase (COX)-2 and p53 expression with prognosis in patients with conventional renal cell carcinoma (RCC). Formalin-fixed, paraffin-embedded tissue sections of conventional RCC from 92 patients, who had undergone radical nephrectomy, were examined for COX-2 and p53 expression by immunohistochemistry and compared with clinicopathological variables. The COX-2 expression significantly correlated only with tumor size (p=0.049), whereas the p53 expression profoundly correlated with the TNM stage (p=0.024), M stage (p=0.001), and metastasis (synchronous or metachronous; p=0.004). The COX-2 overexpression did not significantly associate with p53 positivity (p=0.821). The survival rate of patients correlated with the p53 expression (p<0.0001) but not with the COX-2 expression (p=0.7506). Multivariate analyses indicated that tumor size, M stage, and p53 expression were independent prognostic factors for cancer-specific survival. The COX-2 expression was not an independent factor. These results show that the increased expression of p53 was associated with metastasis and a worse prognosis in conventional RCC, which suggests that p53 might have played an important role in the progression of conventional RCC. The increased expression of COX-2 was associated only with tumor size, but may not be an important prognostic factor in conventional RCC. No association was observed between COX-2 overexpression and p53 positivity in conventional RCC

Differential profiling of breast cancer plasma proteome by isotope-coded affinity tagging method reveals biotinidase as a breast cancer biomarker

<p>Abstract</p> <p>Background</p> <p>Breast cancer is one of the leading causes of women's death worldwide. It is important to discover a reliable biomarker for the detection of breast cancer. Plasma is the most ideal source for cancer biomarker discovery since many cells cross-communicate through the secretion of soluble proteins into blood.</p> <p>Methods</p> <p>Plasma proteomes obtained from 6 breast cancer patients and 6 normal healthy women were analyzed by using the isotope-coded affinity tag (ICAT) labeling approach and tandem mass spectrometry. All the plasma samples used were depleted of highly abundant 6 plasma proteins by immune-affinity column chromatography before ICAT labeling. Several proteins showing differential abundance level were selected based on literature searches and their specificity to the commercially available antibodies, and then verified by immunoblot assays.</p> <p>Results</p> <p>A total of 155 proteins were identified and quantified by ICAT method. Among them, 33 proteins showed abundance changes by more than 1.5-fold between the plasmas of breast cancer patients and healthy women. We chose 5 proteins for the follow-up confirmation in the individual plasma samples using immunoblot assay. Four proteins, α1-acid glycoprotein 2, monocyte differentiation antigen CD14, biotinidase (BTD), and glutathione peroxidase 3, showed similar abundance ratio to ICAT result. Using a blind set of plasmas obtained from 21 breast cancer patients and 21 normal healthy controls, we confirmed that BTD was significantly down-regulated in breast cancer plasma (Wilcoxon rank-sum test, <it>p </it>= 0.002). BTD levels were lowered in all cancer grades (I-IV) except cancer grade zero. The area under the receiver operating characteristic curve of BTD was 0.78. Estrogen receptor status (<it>p </it>= 0.940) and progesterone receptor status (<it>p </it>= 0.440) were not associated with the plasma BTD levels.</p> <p>Conclusions</p> <p>Our study suggests that BTD is a potential serological biomarker for the detection of breast cancer.</p

Fiber-based photon pair generation: a tutorial

The purpose of this tutorial paper is to present a broad overview of photon-pair generation through the spontaneous four wave mixing (SFWM) process in optical fibers. Progress in optical fiber technology means that today we have at our disposal a wide variety of types of fiber, which together with the fact that SFWM uses two pump fields, implies a truly remarkable versatility in the resulting possible photon-pair properties. We discuss how the interplay of the frequency, transverse mode, and polarization degrees of freedom, the first linked to the latter two through fiber dispersion, leads to interesting entanglement properties both in individual degrees of freedom and also permitting hybrid and hyper entanglement in combinations of degrees of freedom. This tutorial covers methods for photon pair factorability, frequency tunability, and SFWM bandwidth control, the effect of frequency non-degenerate and counter-propagating pumps, as well methods for characterizing photon pairs generated in optical fibers.Comment: 21 pages, 9 figure

Stretching of porous poly (l-lactide-co-ε-caprolactone) membranes regulates the differentiation of mesenchymal stem cells

Background: Among a variety of biomaterials supporting cell growth for therapeutic applications, poly (l-lactide-co-ε-caprolactone) (PLCL) has been considered as one of the most attractive scaffolds for tissue engineering owing to its superior mechanical strength, biocompatibility, and processibility. Although extensive studies have been conducted on the relationship between the microstructure of polymeric materials and their mechanical properties, the use of the fine-tuned morphology and mechanical strength of PLCL membranes in stem cell differentiation has not yet been studied.Methods: PLCL membranes were crystallized in a combination of diverse solvent–nonsolvent mixtures, including methanol (MeOH), isopropanol (IPA), chloroform (CF), and distilled water (DW), with different solvent polarities. A PLCL membrane with high mechanical strength induced by limited pore formation was placed in a custom bioreactor mimicking the reproducible physiological microenvironment of the vascular system to promote the differentiation of mesenchymal stem cells (MSCs) into smooth muscle cells (SMCs).Results: We developed a simple, cost-effective method for fabricating porosity-controlled PLCL membranes based on the crystallization of copolymer chains in a combination of solvents and non-solvents. We confirmed that an increase in the ratio of the non-solvent increased the chain aggregation of PLCL by slow evaporation, leading to improved mechanical properties of the PLCL membrane. Furthermore, we demonstrated that the cyclic stretching of PLCL membranes induced MSC differentiation into SMCs within 10 days of culture.Conclusion: The combination of solvent and non-solvent casting for PLCL solidification can be used to fabricate mechanically durable polymer membranes for use as mechanosensitive scaffolds for stem cell differentiation

The lipoxygenase gene family: a genomic fossil of shared polyploidy between Glycine max and Medicago truncatula

<p>Abstract</p> <p>Background</p> <p>Soybean lipoxygenases (<it>Lxs</it>) play important roles in plant resistance and in conferring the distinct bean flavor. <it>Lxs </it>comprise a multi-gene family that includes <it>GmLx1</it>, <it>GmLx2 </it>and <it>GmLx3</it>, and many of these genes have been characterized. We were interested in investigating the relationship between the soybean lipoxygenase isozymes from an evolutionary perspective, since soybean has undergone two rounds of polyploidy. Here we report the tetrad genome structure of soybean <it>Lx </it>regions produced by ancient and recent polyploidy. Also, comparative genomics with <it>Medicago truncatula </it>was performed to estimate <it>Lxs </it>in the common ancestor of soybean and <it>Medicago</it>.</p> <p>Results</p> <p>Two <it>Lx </it>regions in <it>Medicago truncatula </it>showing synteny with soybean were analyzed. Differential evolutionary rates between soybean and <it>Medicago </it>were observed and the median Ks values of Mt-Mt, Gm-Mt, and Gm-Gm paralogs were determined to be 0.75, 0.62, and 0.46, respectively. Thus the comparison of Gm-Mt paralogs (Ks = 0.62) and Gm-Mt orthologs (Ks = 0.45) supports the ancient duplication of <it>Lx </it>regions in the common ancestor prior to the <it>Medicago</it>-<it>Glycine </it>split. After speciation, no <it>Lx </it>regions generated by another polyploidy were identified in <it>Medicago</it>. Instead tandem duplication of <it>Lx </it>genes was observed. On the other hand, a lineage-specific duplication occurred in soybean resulting in two pairs of <it>Lx </it>regions. Each pair of soybean regions was co-orthologous to one <it>Lx </it>region in <it>Medicago</it>. A total of 34 <it>Lx </it>genes (15 <it>MtLxs </it>and 19 <it>GmLxs) </it>were divided into two groups by phylogenetic analysis. Our study shows that the <it>Lx </it>gene family evolved from two distinct <it>Lx </it>genes in the most recent common ancestor.</p> <p>Conclusion</p> <p>This study analyzed two pairs of <it>Lx </it>regions generated by two rounds of polyploidy in soybean. Each pair of soybean homeologous regions is co-orthologous to one region of <it>Medicago</it>, demonstrating the quartet structure of the soybean genome. Differential evolutionary rates between soybean and <it>Medicago </it>were observed; thus optimized rates of Ks per year should be applied for accurate estimation of coalescence times to each case of comparison: soybean-soybean, soybean-<it>Medicago</it>, or <it>Medicago</it>-<it>Medicago</it>. In conclusion, the soybean <it>Lx </it>gene family expanded by ancient polyploidy prior to taxon divergence, followed by a soybean- specific duplication and tandem duplications, respectively.</p

Anti-apoptotic effects of human placental hydrolysate against hepatocyte toxicity in vivo and in vitro

Apoptosis and oxidative stress are essential for the pathogenesis of acute liver failure and fulminant hepatic failure. Human placental hydrolysate (hPH) has been reported to possess antioxidant and anti-inflammatory properties. In the present study, the protective effects of hPH against D-galactosamine (D-GalN)- and lipopolysaccharide (LPS)-induced hepatocyte apoptosis were investigated in vivo. In addition, the molecular mechanisms underlying the anti-apoptotic activities of hPH against D-GalN-induced cell death in vitro were examined. Male Sprague-D awley rats were injected with D-GaIN/LPS with or without the administration of hPH. Rats were sacrificed 24 h after D-GaIN/LPS intraperitoneal injection, and the blood and liver samples were collected for future inflammation and hepatotoxicity analyses. Changes in cell viability, apoptosis protein expression, mitochondrial mass, mitochondrial membrane potential, reactive oxygen species generation, and the levels of proteins and mRNA associated with a protective mechanism were determined in HepG2 cells pretreated with hPH for 2 h prior to D-GalN exposure. The findings suggested that hPH treatment effectively protected against D-GalN/LPS-induced hepatocyte apoptosis by reducing the levels of alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, interleukin-6, and tumor necrosis factor-α, and increasing the level of proliferating cell nuclear antigen. It was also found that hPH inhibited the apoptotic cell death induced by D-GalN. hPH activated the expression of antioxidant enzymes, including superoxide dismutase, glutathione peroxidase, and catalase, which were further upregulated by the Kelch-like ECH2-associated protein 1-p62-nuclear factor-erythroid 2-related factor 2 pathway, a component of oxidative stress defense mechanisms. Furthermore, hPH markedly reduced cytosolic and mitochondrial reactive oxygen species and rescued mitochondrial loss and dysfunction through the reduction of damage-regulated autophagy modulator, p53, and C/EBP homologous protein. Collectively, hPH exhibited a protective role in hepatocyte apoptosis by inhibiting oxidative stress and maintaining cell homeostasis. The underlying mechanisms may be associated with the inhibition of endoplasmic reticulum stress and minimization of the autophagy progress