Klotho protein contributes to cardioprotection during ischaemia/reperfusion injury

Restoration of blood flow to ischaemic heart inflicts ischaemia/reperfusion (I/R) injury, which manifests in metabolic and morphological disorders. Klotho is a protein with antioxidative and antiapoptotic activity, and is involved in the regulation of inflammation and fibrosis. The aim of the current research was to determine the role of Klotho in the heart subjected to I/R injury, as well as to study Klotho as a potential cardioprotective agent. Human cardiomyocytes and Wistar rat hearts perfused using Langendorff method subjected to I/R have been used. Hemodynamic parameters of heart function, markers of I/R injury, and gene and protein expression of Klotho were measured. Human cardiomyocytes were also incubated in the presence of recombinant Klotho protein, and the viability of cells was measured. There was a higher expression of Klotho gene and protein synthesis in the cardiomyocytes subjected to I/R injury. The compensatory production and release of Klotho protein from cardiac tissue during I/R were also shown. The treatment of cardiomyocytes subjected to I/R with Klotho protein resulted in increased viability and metabolic activity of cells. Thus, Klotho contributes to compensatory mechanism during I/R, and could be used as a marker of injury and as a potential cardiopreventive/cardioprotective agent.     

The kinetics of nicotine degradation,enzyme activities and genotoxic potential in the characterization of tobacco waste composting

This study aimed to determine nicotine biodegradation and the genotoxic potential of nicotine and its degradation products during the process of tobacco waste composting. Composting was carried out using two methods, i.e. the addition of 20% (bioreactor A) or 40% tobacco wastes to sewage sludge (bioreactor B) and control – sewage sludge (bioreactor C). Wheat straw was used as a structure-forming material. As a result of composting the contents of C and N in the bioreactors changed, the C:N ratio in bioreactor A changed from 22.8 to 13.00, and that in bioreactor B changed from 23.5 to 12.00. After composting, the biodegradation rate of nicotine was 78% in bioreactor A and 80% in bioreactor B, respectively. Using the Ames test it was shown that the composts produced did not exhibit mutagenicity.     

A Comparison of the Effects of Ocular Preservatives on Mammalian and Microbial ATP and Glutathione Levels

The aim of this study was to investigate the mechanism of action of the preservative sodium chlorite (NaClO²), and the relationship with intracellular glutathione depletion. A detailed comparison of the dose responses of two cultured ocular epithelial cell types and four species of microorganism was carried out, and comparisons were also made with the quaternary ammonium compound benzalkonium chloride (BAK), and the oxidant hydrogen peroxide (H²O²). The viability of mammalian and microbial cells was assessed in the same way, by the measurement of intracellular ATP using a bioluminescence method. Intracellular total glutathione was measured by reaction with 5,5′-dithiobis-2-nitrobenzoic acid in a glutathione reductase-dependent recycling assay. BAK and H²O² caused complete toxicity to conjunctival and corneal epithelial cells at ～25?ppm, in contrast to NaClO², where >100?ppm was required. The fungi Candida albicans and Alternaria alternata had a higher resistance to NaClO² than the bacteria Staphyloccus aureus and Pseudomonas aeruginosa, but the bacteria were extremely resistant to H²O². NaClO² caused substantial depletion of intracellular glutathione in all cell types, at concentrations ranging from <10?ppm in Pseudomonas, 25–100?ppm in epithelial cells, to >500?ppm in fungal cells. The mechanisms of cytotoxicity of NaClO², H²O² and BAK all appeared to differ. NaClO² was found to have the best balance of high antibacterial toxicity with low ocular toxicity. The lower toxicity of NaClO² to the ocular cells, compared with BAK and H²O², is in agreement with fewer reported adverse effects of application in the eye.     

Mechanisms of resistance to BCR-ABL and other kinase inhibitors

In this article, we are reviewing the molecular mechanisms that lead to kinase inhibitor resistance. As the oncogenic BCR-ABL kinase is the target of the first approved small-molecule kinase inhibitor imatinib, we will first focus on the structural and mechanistic basis for imatinib resistance. We will then show ways how next generations of BCR-ABL inhibitors and alternative targeting strategies have helped to offer effective treatment options for imatinib-resistant patients. Based on these insights, we discuss commonalities and further mechanisms that lead to resistance to other kinase inhibitors in solid tumors. This article is part of a Special Issue entitled: Inhibitors of Protein Kinases (2012).     

Ecosystem respiration in a heterogeneous temperate peatland and its sensitivity to peat temperature and water table depth

Background and aims

Ecosystem respiration (R _eco ) is controlled by thermal and hydrologic regimes, but their relative importance in defining the CO₂ emissions in peatlands seems to be site specific. The aim of the paper is to investigate the sensitivity of R _eco to variations in temperature and water table depth (WTD) in a wet, geogenous temperate peatland with a wide variety of vegetation community groups.

Methods

The CO₂ fluxes were measured using chambers. Measurements were made at four microsites with different vegetation communities and peat moisture and temperature conditions every 3 to 4 weeks during the period 2008–2009, 2 years with contrasting WTD patterns. Models were used to examine the relative response of each microsite to variations in peat temperature and WTD and used to estimate annual total R _eco .

Results

Temporal variations in R _eco were strongly related to peat temperature at the 5 cm depth. However, two of the microsites did not show any significant change in this relationship while two others showed contrasting responses including an increase and decrease in temperature sensitivity with deeper WTD. Average R _eco varied among the microsites and tended to be greatest for those with greatest leaf area which also positively correlated with deeper WTD, ash content and degree of peat decomposition at 20 cm. A combined temperature and WTD model explained up to 94 % of the temporal variation in daily average R _eco and was used to show that on an annual basis, R _eco was between 5 and 18 % greater in the warmer year with deeper WTD.

Conclusion

Microsite-specific responses were related to differences in vegetation and peat characteristics among microsites. R _eco may have remained insensitive to WTD variations at one microsite due to the dominance of autotrophic respiration from abundant sedge biomass. At a Sphagnum-dominated microsite, a lack of response may have been due to relatively small variations in WTD that did not greatly influence microbial respiration or due to offsets between decreasing and increasing respiration rates in near-surface and deeper peat. The microsite with the most recalcitrant peat had reduced R _eco sensitivity to temperature under more aerobic conditions while another microsite showed the opposite response, perhaps due to less nutrient availability during the wet year. Ultimately, micro-site specific models with both soil temperature and WTD as explanatory variables described temporal variations in R _eco and highlighted the significant spatial variations in respiration rates that may occur within a single wetland.     

N-cadherin antagonists as oncology therapeutics

The cell adhesion molecule (CAM), N-cadherin, has emerged as an important oncology therapeutic target. N-cadherin is a transmembrane glycoprotein mediating the formation and structural integrity of blood vessels. Its expression has also been documented in numerous types of poorly differentiated tumours. This CAM is involved in regulating the proliferation, survival, invasiveness and metastasis of cancer cells. Disruption of N-cadherin homophilic intercellular interactions using peptide or small molecule antagonists is a promising novel strategy for anti-cancer therapies. This review discusses: the discovery of N-cadherin, the mechanism by which N-cadherin promotes cell adhesion, the role of N-cadherin in blood vessel formation and maintenance, participation of N-cadherin in cancer progression, the different types of N-cadherin antagonists and the use of N-cadherin antagonists as anti-cancer drugs.     

Recombinant Lloviu virus as a tool to study viral replication and host responses

Next generation sequencing has revealed the presence of numerous RNA viruses in animal reservoir hosts, including many closely related to known human pathogens. Despite their zoonotic potential, most of these viruses remain understudied due to not yet being cultured. While reverse genetic systems can facilitate virus rescue, this is often hindered by missing viral genome ends. A prime example is Lloviu virus (LLOV), an uncultured filovirus that is closely related to the highly pathogenic Ebola virus. Using minigenome systems, we complemented the missing LLOV genomic ends and identified cis-acting elements required for LLOV replication that were lacking in the published sequence. We leveraged these data to generate recombinant full-length LLOV clones and rescue infectious virus. Similar to other filoviruses, recombinant LLOV (rLLOV) forms filamentous virions and induces the formation of characteristic inclusions in the cytoplasm of the infected cells, as shown by electron microscopy. Known target cells of Ebola virus, including macrophages and hepatocytes, are permissive to rLLOV infection, suggesting that humans could be potential hosts. However, inflammatory responses in human macrophages, a hallmark of Ebola virus disease, are not induced by rLLOV. Additional tropism testing identified pneumocytes as capable of robust rLLOV and Ebola virus infection. We also used rLLOV to test antivirals targeting multiple facets of the replication cycle. Rescue of uncultured viruses of pathogenic concern represents a valuable tool in our arsenal for pandemic preparedness.     

CD40L and IL-4 stimulation of acute lymphoblastic leukemia cells results in upregulation of mRNA level of FLICE--an important component of apoptosis

The use of cancer vaccines based on dendritic cells (DC) presenting tumor antigens can be a promising tool in the treatment of leukemia. The functional characteristics of leukemia derived DC is still to be elucidated. CD40 promotes survival, proliferation and differentiation of normal B cells. CD40 triggering was used to enhance the poor antigen-presenting capacity of leukemic B-cells. Since it is still unclear whether CD40 ligation drives neoplastic B-cells to apoptosis or not, we assessed the mRNA expression of FLICE, FAS, FADD and TRADD - important components of apoptosis machinery, using real-time PCR in acute lymphoblastic leukemia cells before and after CD40 and IL-4 stimulation. ALL cells stimulated with CD40L/IL-4 expressed dendritic cell phenotype at mRNA and protein levels (upregulation of main costimulatory and adhesion molecules noted in real-time RT PCR and flow cytometry); they also expressed higher amounts of mRNA for FLICE, TRADD and FADD after CD40L/IL-4 stimulation. However differences statistically significant comparing cells cultured with CD40L/IL-4 and medium alone regarded only FLICE. Concluding, we showed upregulation of important elements of apoptosis at mRNA level in ALL cells after CD40 ligation.