Inhibitory effect of acetylsalicylic acid on matrix metalloproteinase - 2 activity in human endothelial cells exposed to high glucose

Matrix metalloproteinases play a major role in the process of angiogenesis, an important feature of diabetes complications, cancer or rheumatoid arthritis. High glucose concentrations were reported to augment metalloproteinase-2 secretion in some cell types. In the present study we investigated the influence of acetylsalicylic acid on metalloproteinase- 2 secretion and expression in endothelial cells cultured for one week in high glucose conditions (25 mM and 33 mM). Metalloproteinase-2 activity was evidenced by gel zymography, the protein was identified by Western blotting, and the gene expression was quantitated by RT-PCR. The results indicated a marked inhibitory effect of acetylsalicylic acid at gene expression level (approximately 43%) and also at secretion level in samples of conditioned media (approximately 30%) and cellular homogenates (approximately 70%). This may suggest that acetylsalicylic acid could have a beneficial effect in preventing the angiogenic process that appears in diabetes complications.     

QT-RR hysteresis is caused by differential autonomic states during exercise and recovery

QT-RR hysteresis is characterized by longer QT intervals at a given RR interval while heart rates are increasing during exercise and shorter QT intervals at the same RR interval while heart rates are decreasing during recovery. It has been attributed to a lagging QT response to different directional changes in RR interval during exercise and recovery. Twenty control subjects (8 males, age 51 ± 6 yr), 16 subjects with type 2 diabetes (12 males, age 56 ± 8 yr), 71 subjects with coronary artery disease (CAD) and preserved left ventricular ejection fraction (LVEF) (≥50%) (51 males, age 59 ± 12 yr), and 17 CAD subjects with depressed LVEF (<50%) (13 males, age 57 ± 10 yr) underwent two 16-min exercise tests followed by recovery. In session 2, parasympathetic blockade with atropine (0.04 mg/kg) was achieved at end exercise. QT-RR hysteresis was quantified as: 1) the area bounded by the QT-RR relationships for exercise and recovery in the range of the minimum RR interval at peak exercise to the minimum RR interval + 100 ms and 2) the difference in QT interval duration between exercise and recovery at the minimum RR interval achieved during peak exercise plus 50 ms (ΔQT). The effect of parasympathetic blockade was assessed by substituting the QT-RR relationship after parasympathetic blockade. QT-RR hysteresis was positive in all groups at baseline and reversed by parasympathetic blockade (P < 0.01). We conclude that QT-RR hysteresis is not caused by different directional changes in RR interval during exercise and recovery. Instead, it is predominantly mediated by differential autonomic nervous system effects as the heart rate increases during exercise vs. as it decreases during recovery.     

A “yellow” laccase with “blue” spectroscopic features,from Sclerotinia sclerotiorum

Reported here are the production, purification and characterization of a laccase from the phytophathogenic fungus Sclerotinia sclerotiorum. This laccase is identified by mass spectrometry with a sequence coverage of 74.9% (458/577 AA) revealing that the protein is identical or highly homologous to a predicted oxidoreductase from this species (A7EM18 in the Uniprot database); the closest homologous protein previously isolated from a fungus is the Melanocarpus albomyces, with only 35% identity. The UV–vis spectral features of this laccase classify it as a “yellow” one. The EPR spectrum nevertheless demonstrates resemblance to blue laccases – including the type 1 center not detectable in UV–vis spectra. The presence of type 3 coppers was proven by fluorescence spectrum and by 330 nm band in UV–vis. The purified laccase has an apparent molecular mass of 70 kDa and appears as a monomer. The values of K_M and k_cat were determined for ABTS, 2,6-dimethoxyphenol, p-phenylenediamine and guaicol and are typical of a laccase. The optimal pH value is around 4 except for ABTS, for which activity is linearly increasing with acidity. The high laccase activity in liquid culture makes S. sclerotiorum a useful source of laccase for practical applications.     

Autophagy-dependent senescence in response to DNA damage and chronic apoptotic stress

Autophagy regulates cell survival and cell death upon various cellular stresses, yet the molecular signaling events involved are not well defined. Here, we established the function of a proteolytic Cyclin E fragment (p18-CycE) in DNA damage-induced autophagy, apoptosis, and senescence. p18-CycE was identified in hematopoietic cells undergoing DNA damage-induced apoptosis. In epithelial cells exposed to DNA damage, chronic but not transient expression of p18-CycE leads to higher turnover of LC3 I/II and increased emergence of autophagosomes and autolysosomes. Levels of p18-CycE, which was generated by proteolytic cleavage of endogenous Cyclin E, were greatly increased by chloroquine and correlated with LC 3II conversion. Preventing p18-CycE genesis blocked conversion of LC3 I to LC3 II. Upon DNA damage, cytoplasmic ataxia-telangiectasia-mutated (ATM) was phosphorylated in p18-CycE-expressing cells resulting in sustained activation of the adenosine-mono-phosphate-dependent kinase (AMPK). These lead to sustained activation of mammalian autophagy-initiating kinase ULK1, which was abrogated upon inhibiting ATM and AMPK phosphorylation. Moreover, p18-CycE was degraded via autophagy followed by induction of senescence. Both autophagy and senescence were prevented by inhibiting autophagy, which leads to increased apoptosis in p18-CycE-expressing cells by stabilizing p18-CycE expression. Senescence was further associated with cytoplasmic co-localization and degradation of p18-CycE and Ku70. In brief, chronic p18-CycE expression-induced autophagy leads to clearance of p18-CycE following DNA damage and induction of senescence. Autophagy inhibition stabilized the cytoplasmic p18-CycE-Ku70 complex leading to apoptosis. Thus, our findings define how chronic apoptotic stress and DNA damage initiate autophagy and regulate cell survival through senescence and/or apoptosis.     

Improvement of daytime rapid eye movement parameters following a hot bath in night-shift workers

Sleep and Biological Rhythms - The sleep-promoting effect of a hot bath on daytime sleep after night-shift work was assessed by polysomnography. Having an unlimited daytime sleep opportunity,...     

A safe and complete algorithm for metagenomic assembly

Background

Reconstructing the genome of a species from short fragments is one of the oldest bioinformatics problems. Metagenomic assembly is a variant of the problem asking to reconstruct the circular genomes of all bacterial species present in a sequencing sample. This problem can be naturally formulated as finding a collection of circular walks of a directed graph G that together cover all nodes, or edges, of G.

Approach

We address this problem with the “safe and complete” framework of Tomescu and Medvedev (Research in computational Molecular biology—20th annual conference, RECOMB 9649:152–163, 2016). An algorithm is called safe if it returns only those walks (also called safe) that appear as subwalk in all metagenomic assembly solutions for G. A safe algorithm is called complete if it returns all safe walks of G.

Results

We give graph-theoretic characterizations of the safe walks of G, and a safe and complete algorithm finding all safe walks of G. In the node-covering case, our algorithm runs in time \(O(m^2 + n^3)\), and in the edge-covering case it runs in time \(O(m^2n)\); n and m denote the number of nodes and edges, respectively, of G. This algorithm constitutes the first theoretical tight upper bound on what can be safely assembled from metagenomic reads using this problem formulation.

     

Early Evaluation and Monitoring of Critical Patients with Acute Respiratory Distress Syndrome (ARDS) Using Specific Genetic Polymorphisms

A high percentage of critical patients are found to develop acute respiratory distress syndrome (ARDS). Several studies have reported high mortality rates in these cases which are most frequently associated with multiple organ dysfunctions syndrome. Lately, many efforts have been made to evaluate and monitor ARDS in critical patients. In this regard, the assessment of genetic polymorphisms responsible for developing ARDS present as a challenge and are considered future biomarkers. Early detection of the specific polymorphic gene responsible for ARDS in critically ill patients can prove to be a useful tool in the future, able to help decrease the mortality rates in these cases. Moreover, identifying the genetic polymorphism in these patients can help in the implementation of a personalized intensive therapy scheme for every type of patient, based on its genotype.     

Thioureides of 2-(phenoxymethyl)benzoic acid 4-R substituted: A novel class of anti-parasitic compounds

Fifty members of a novel class of antimicrobial compounds, 2-(4-R-phenoxymethyl)benzoic acid thioureides, were synthesized and characterized with respect to their activities against three parasites of human relevance, namely the protozoa Giardia lamblia and Toxoplasma gondii, and the larval (metacestode) stage of the tapeworm Echinococcus multilocularis. To determine the selective toxicity of these compounds, the human colon cancer cell line Caco2 and primary cultures of human foreskin fibroblasts (HFF) were also investigated. The new thioureides were obtained in a three-step-reaction process and subsequently characterized by their physical constants (melting point, solubility). The chemical structures were elucidated by ¹H NMR, ¹³C NMR, IR spectral methods and elemental analysis. The analyses confirmed the final and intermediate compound structures and the synthesis. The compounds were then tested on the parasites in vitro. All thioureides, except two compounds with a nitro group, were totally ineffective against Giardia lamblia. 23 compounds inhibited the proliferation of T. gondii, three of them with an IC₅₀ of approximately 1 μM. The structural integrity of E. multilocularis metacestodes was affected by 22 compounds. In contrast, HFF were not susceptible to any of these thioureides, while Caco2 cells were affected by 17 compounds, two of them inhibiting proliferation with an IC₅₀ in the micromolar range. Thioureides may thus present a promising class of anti-infective agents.