Acid stress-mediated metabolic shift in Lactobacillus sanfranciscensis LSCE1

Lactobacillus sanfranciscensis LSCE1 was selected as a target organism originating from recurrently refreshed sourdough to study the metabolic rerouting associated with the acid stress exposure during sourdough fermentation. In particular, the acid stress induced a metabolic shift toward overproduction of 3-methylbutanoic and 2-methylbutanoic acids accompanied by reduced sugar consumption and primary carbohydrate metabolite production. The fate of labeled leucine, the role of different nutrients and precursors, and the expression of the genes involved in branched-chain amino acid (BCAA) catabolism were evaluated at pH 3.6 and 5.8. The novel application of the program XCMS to the solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) data allowed accurate separation and quantification of 2-methylbutanoic and 3-methylbutanoic acids, generally reported as a cumulative datum. The metabolites coming from BCAA catabolism increased up to seven times under acid stress. The gene expression analysis confirmed that some genes associated with BCAA catabolism were overexpressed under acid conditions. The experiment with labeled leucine showed that 2-methylbutanoic acid originated also from leucine. While the overproduction of 3-methylbutanoic acid under acid stress can be attributed to the need to maintain redox balance, the rationale for the production of 2-methylbutanoic acid from leucine can be found in a newly proposed biosynthesis pathway leading to 2-methylbutanoic acid and 3 mol of ATP per mol of leucine. Leucine catabolism to 3-methylbutanoic and 2-methylbutanoic acids suggests that the switch from sugar to amino acid catabolism supports growth in L. sanfranciscensis in restricted environments such as sourdough characterized by acid stress and recurrent carbon starvation.     

Measurement of warfarin in the oral fluid of patients undergoing anticoagulant oral therapy

Background

Patients on warfarin therapy undergo invasive and expensive checks for the coagulability of their blood. No information on coagulation levels is currently available between two controls.

Methodology

A method was developed to determine warfarin in oral fluid by HPLC and fluorimetric detection. The chromatographic separation was performed at room temperature on a C-18 reversed-phase column, 65% PBS and 35% methanol mobile phase, flow rate 0.7 mL/min, injection volume 25 µL, excitation wavelength 310 nm, emission wavelength 400 nm.

Findings

The method was free from interference and matrix effect, linear in the range 0.2–100 ng/mL, with a detection limit of 0.2 ng/mL. Its coefficient of variation was <3% for intra-day measurements and <5% for inter-day measurements. The average concentration of warfarin in the oral fluid of 50 patients was 2.5±1.6 ng/mL (range 0.8–7.6 ng/mL). Dosage was not correlated to INR (r = −0.03, p = 0.85) but positively correlated to warfarin concentration in the oral fluid (r = 0.39, p = 0.006). The correlation between warfarin concentration and pH in the oral fluid (r = 0.37, p = 0.009) confirmed the importance of pH in regulating the drug transfer from blood. A correlation between warfarin concentration in the oral fluid and INR was only found in samples with pH values ≥7.2 (r = 0.84, p = 0.004).

Conclusions

Warfarin diffuses from blood to oral fluid. The method allows to measure its concentration in this matrix and to analyze correlations with INR and other parameters.     

MiR-34a targeting of Notch ligand delta-like 1 impairs CD15+/CD133+ tumor-propagating cells and supports neural differentiation in medulloblastoma

Background

Through negative regulation of gene expression, microRNAs (miRNAs) can function as oncosuppressors in cancers, and can themselves show altered expression in various tumor types. Here, we have investigated medulloblastoma tumors (MBs), which arise from an early impairment of developmental processes in the cerebellum, where Notch signaling is involved in many of the cell-fate-determining stages. Notch regulates a subset of MB cells that have stem-cell-like properties and can promote tumor growth. On the basis of this evidence, we hypothesized that miRNAs targeting the Notch pathway can regulate these phenomena, and can be used in anti-cancer therapies.

Methodology/Principal Findings

In a screening of potential targets within Notch signaling, miR-34a was seen to be a regulator of the Notch pathway through its targeting of Notch ligand Delta-like 1 (Dll1). Down-regulation of Dll1 expression by miR-34a negatively regulates cell proliferation, and induces apoptosis and neural differentiation in MB cells. Using an inducible tetracycline on-off model of miR-34a expression, we show that in Daoy MB cells, Dll1 is the first target that is regulated in MB, as compared to the other targets analyzed here: Cyclin D1, cMyc and CDK4. MiR-34a expression negatively affects CD133⁺/CD15⁺ tumor-propagating cells, then we assay through reverse-phase proteomic arrays, Akt and Stat3 signaling hypo-phosphorylation. Adenoviruses carrying the precursor miR-34a induce neurogenesis of tumor spheres derived from a genetic animal model of MB (Patch1^+/- p53^-/-), thus providing further evidence that the miR-34a/Dll1 axis controls both autonomous and non autonomous signaling of Notch. In vivo, miR-34a overexpression carried by adenoviruses reduces tumor burden in cerebellum xenografts of athymic mice, thus demonstrating an anti-tumorigenic role of miR-34a in vivo.

Conclusions/Significance

Despite advances in our understanding of the pathogenesis of MB, one-third of patients with MB remain incurable. Here, we show that stable nucleic-acid-lipid particles carrying mature miR-34a can target Dll1 in vitro and show equal effects to those of adenovirus miR-34a cell infection. Thus, this technology forms the basis for their therapeutic use for the delivery of miR-34a in brain-tumor treatment, with no signs of toxicity described to date in non-human primate trials.     

Differential production of insulin-like growth factor-binding proteins in liver fibrosis progression

Molecular and Cellular Biochemistry - Curcumin (Cur) is widely used as an anti-inflammation agent and has anti-depression potential. Neuroinflammation mediated by Ca2+ channel activation is closely...     

Ion Migration‐Induced Amorphization and Phase Segregation as a Degradation Mechanism in Planar Perovskite Solar Cells

The operation of halide perovskite optoelectronic devices, including solar cells and LEDs, is strongly influenced by the mobility of ions comprising the crystal structure. This peculiarity is particularly true when considering the long‐term stability of devices. A detailed understanding of the ion migration‐driven degradation pathways is critical to design effective stabilization strategies. Nonetheless, despite substantial research in this first decade of perovskite photovoltaics, the long‐term effects of ion migration remain elusive due to the complex chemistry of lead halide perovskites. By linking materials chemistry to device optoelectronics, this study highlights that electrical bias‐induced perovskite amorphization and phase segregation is a crucial degradation mechanism in planar mixed halide perovskite solar cells. Depending on the biasing potential and the injected charge, halide segregation occurs, forming crystalline iodide‐rich domains, which govern light emission and participate in light absorption and photocurrent generation. Additionally, the loss of crystallinity limits charge collection efficiency and eventually degrades the device performance.     

Uric Acid as a Risk Factor for Cardiovascular Disease and Mortality in Overweight/Obese Individuals

Background

The predictive value of serum uric acid (SUA) for adverse cardiovascular events among obese and overweight patients is not known, but potentially important because of the relation between hyperuricaemia and obesity.

Methods

The relationship between SUA and risk of cardiovascular adverse outcomes (nonfatal myocardial infarction, nonfatal stroke, resuscitated cardiac arrest or cardiovascular death) and all-cause mortality, respectively, was evaluated in a post-hoc analysis of the Sibutramine Cardiovascular OUTcomes (SCOUT) trial. Participants enrolled in SCOUT were obese or overweight with pre-existing diabetes and/or cardiovascular disease (CVD). Cox models were used to assess the role of SUA as an independent risk factor.

Results

9742 subjects were included in the study; 83.6% had diabetes, and 75.1% had CVD. During an average follow-up time of 4.2 years, 1043 subjects had a primary outcome (myocardial infarction, resuscitated cardiac arrest, stroke, or cardiovascular death), and 816 died. In a univariate Cox model, the highest SUA quartile was associated with an increased risk of cardiovascular adverse outcomes compared with the lowest SUA quartile in women (hazard ratio [HR]: 1.59; 95% confidence interval [CI]: 1.20–2.10). In multivariate analyses, adjusting for known cardiovascular risk factors the increased risk for the highest SUA quartile was no longer statistically significant among women (HR: 0.99; 95% CI: 0.72–1.36) nor was it among men. Analyses of all-cause mortality found an interaction between sex and SUA. In a multivariate Cox model including women only, the highest SUA quartile was associated with an increased risk in all-cause mortality compared to the lowest SUA quartile (HR: 1.51; 95% CI: 1.08–2.12). No relationship was observed in men (HR: 1.06; 95% CI: 0.82–1.36).

Conclusion

SUA was not an independent predictor of cardiovascular disease and death in these high-risk overweight/obese people. However, our results suggested that SUA was an independent predictor of all-cause mortality in women.     

Diversity of Cacao Trees in Waslala,Nicaragua: Associations between Genotype Spectra,Product Quality and Yield Potential

The sensory quality and the contents of quality-determining chemical compounds in unfermented and fermented cocoa from 100 cacao trees (individual genotypes) representing groups of nine genotype spectra (GG), grown at smallholder plantings in the municipality of Waslala, Nicaragua, were evaluated for two successive harvest periods. Cocoa samples were fermented using a technique mimicking recommended on-farm practices. The sensory cocoa quality was assessed by experienced tasters, and seven major chemical taste compounds were quantified by near infrared spectrometry (NIRS). The association of the nine, partially admixed, genotype spectra with the analytical and sensory quality parameters was tested. The individual parameters were analyzed as a function of the factors GG and harvest (including the date of fermentation), individual trees within a single GG were used as replications. In fermented cocoa, significant GG-specific differences were observed for methylxanthines, theobromine-to-caffeine (T/C) ratio, total fat, procyanidin B5 and epicatechin, as well as the sensory attributes global score, astringency, and dry fruit aroma, but differences related to harvest were also apparent. The potential cocoa yield was also highly determined by the individual GG, although there was significant tree-to-tree variation within every single GG. Non-fermented samples showed large harvest-to-harvest variation of their chemical composition, while differences between GG were insignificant. These results suggest that selection by the genetic background, represented here by groups of partially admixed genotype spectra, would be a useful strategy toward enhancing quality and yield of cocoa in Nicaragua. Selection by the GG within the local, genetically segregating populations of seed-propagated cacao, followed by clonal propagation of best-performing individuals of the selected GG could be a viable alternative to traditional propagation of cacao by seed from open pollination. Fast and gentle air-drying of the fermented beans and their permanent dry storage were an efficient and comparatively easy precondition for high cocoa quality.     

Viability Is Associated with Melanin-Based Coloration in the Barn Swallow (Hirundo rustica)

Pigmentation of body surface in animals can have multiple determinants and accomplish diverse functions. Eumelanin and pheomelanin are the main animal pigments, being responsible of yellow, brownish-red and black hues, and have partly common biosynthetic pathways. Many populations of vertebrates show individual variation in melanism, putatively with large heritable component. Genes responsible for eu- or pheomelanogenesis have pleiotropic but contrasting effects on life-history traits, explaining the patterns of covariation observed between melanization and physiology (e.g. immunity and stress response), sexual behavior and other characters in diverse taxa. Yet, very few studies in the wild have investigated if eu- and pheomelanization predict major fitness traits like viability or fecundity. In this correlative study, by contrasting adult barn swallows (Hirundo rustica) matched for age, sex, breeding site, and year and date of sampling, we show that males but not females that survived until the next year had paler, relatively more eu- than pheomelanic pigmentation of ventral body feathers. Better performance of individuals that allocate relatively more to eumelanogenesis was expected based on previous evidence on covariation between eumelanic pigmentation and specific traits related to immunity and susceptibility to stress. However, together with the evidence of no covariation between viability and melanization among females, this finding raises the question of the mechanisms that maintain variation in genes for melanogenesis. We discuss the possibility that eu- and pheomelanization are under contrasting viability and sexual selection, as suggested by larger breeding and sperm competition success of darker males from other barn swallow subspecies.