Sensitive determination of carbidopa through the electrochemiluminescence of luminol at graphene‐modified electrodes

Using the concept of electrogenerated chemiluminescence (ECL), a sensitive analytical method for the determination of carbidopa is described. Electro‐oxidation of carbidopa on the surface of a graphene oxide (GO)‐modified gold electrode (GE) leads to enhancement of the weak emission of oxidized luminol. Under optimum experimental conditions, the ECL signal increases linearly with increasing carbidopa concentrations over a range of 1.0 × 10^‐9–1.7 × 10^‐7 M, with a detection limit of 7.4 × 10^‐10 M. The proposed ECL method was successfully used for the determination of carbidopa in urine samples. Copyright © 2014 John Wiley & Sons, Ltd.     

Host-Guest Interactions as a Model for the Solvent Influence on the Conformational Populations in [2.2.2.2]Paracyclophane

The interaction of a number of small organic molecules with the two lowest energy minimum conformations of [2.2.2.2]paracyclophane (4°-PCP), 1 and 2, are studied by MMP2(87) force field calculations. Formations of nesting as well as inclusion complexes were identified on the potential energy surface. With CH₂Cl₂ and CHCl₃ used as guests, the nesting complexes are lower in energy than the inclusion ones with both conformations 1 and 2. Furthermore, the nesting complexes with 2 are found to be more stable than the nesting ones with 1. Formation of the double nesting complexes of CH₂Cl₂ and CHCl₃ with 1 and 2 raise the difference in complexation energy in favour of 2. The preference of 4°-PCP for the form 2 in solution is explained based on the above analysis, although 2 is calculated to be 0.2 kcal·mol^–1 higher in steric energy than 1 in the gas phase.Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1007/s0089490050218     

Molecular Dynamics Study of the Human Beta-defensins 2 and 3 Chimeric Peptides with the Cell Membrane Model of Pseudomonas aeruginosa

International Journal of Peptide Research and Therapeutics - Pseudomonas aeruginosa is a unique microorganism among the antibiotic-resistant microbial pathogens. Among the various therapeutic...     

Oxidative stress in broad bean (Vicia faba L.) induced by static magnetic field under natural radioactivity

The investigation was performed to evaluate the influence of the static magnetic field on oxidative stress in Vicia faba cultivated in soil from high background natural radioactivity in Iran. Soil samples were collected from Ramsar, Iran where the annual radiation absorbed dose from background radiation is substantially higher than 20 mSv/year. The soil samples were then divided into 2 separate groups including high and low natural radioactivity. The plants were continuously exposed to static magnetic field of 15 mT for 8 days, each 8h/day. The results showed that in the plants cultivated in soils with high background natural radioactivity and low background natural radioactivity the activity of antioxidant enzymes as well as flavonoid content were lower than those of the control. Treatment of plants with static magnetic field showed similar results in terms of lowering of antioxidant defense system and increase of peroxidation of membrane lipids. Accumulation of ROS also resulted in chromosomal aberration and DNA damage. This phenomenon was more pronounced when a combination of natural radiation and treatment with static magnetic field was applied. The results suggest that exposure to static magnetic field causes accumulation of reactive oxygen species in V. faba and natural radioactivity of soil exaggerates oxidative stress.     

Phylogenetic study of SIVcpz MT145 virus based on proteome and genome analysis

Molecular phylogenetic studies were performed by the alignment of protein/nucleotide sequences of human/simian immunodeficiency virus (HIV/SIV), followed by the construction of phylograms according to maximum likelihood method. We aimed to investigate the evolutionary relationship of the recombinant SIVcpzMT145, to other well-known SIVcpz and HIV-1 viruses. Expectedly, MT145 follows the rule of feasible recombination occurrence in SIVcpz clade as to it consists several recombinations in different genome sites including gag, Pol, and Env region. Phylograms indicated that in Pol gene, MT145 is more related to GAB1 and CAM13 SIVs; while in Env gene, it has a closed relationship to GAB2 SIV. Moreover, MT145 differs from other SIVcpzPtt strains in the Env V3 loop having the QIGPAMT motif (same as HIV-1N), instead of usual QIGPGMT motif in these strains. Data indicated that the Env proteins contain considerable amino acid sequence diversification. Overall, this study suggests that, parts of the Gag and especially Vpu/Env gene sequences of SIVcpzMT145 were derived from an unknown SIVcpz lineage ancestral to HIV-1 group M/MB66.     

Investigation on functional and numerical responses of Encarsia acaudaleyrodis parasitizing Bemisia tabaci on cucumber

Functional and numerical responses of Encarsia acaudaleyrodis Hayat parasitizing Bemisia tabaci Gennadius were investigated under laboratory conditions. Newly emerged pairs of parasitoids were confined for 24 h in 8 cm Petri dishes together with 5, 10, 20, 40, 60, or 100 individuals of B. tabaci at their third nymphal stage. The parasitoid exhibited a type II functional response, attacking up to 9.6 nymphs when 100 had been provided. The rate of attack and handling time were 0.0554 and 2.3068 h, respectively. The number of eggs deposited by a single parasitoid depended on the number of host individuals, the maximum being 44.4 when the number of nymphs was 100. At the above-mentioned densities, the parasitoid lived 8.5 days on average.     

Prevalent mutations of human prion protein: a molecular modeling and molecular dynamics study

Point mutations in the human prion protein gene, leading to amino acid substitutions in the human prion protein contribute to conversion of PrPC to PrPSc and amyloid formation, resulting in prion diseases such as familial Creutzfeldt-Jakob disease (CJD), Gerstmann-Straussler-Scheinker disease (GSS), and fatal familial insomnia. We have investigated impressions of prevalent mutations including Q217R, D202N, F198S, on the human prion protein and compared the mutant models with wild types. Structural analyses of models were performed with molecular modeling and molecular dynamics simulation methods. According to our results, frequently occurred mutations are observed in conserved and fully conserved sequences of human prion protein and the most fluctuation values occur in the Helix 1 around residues 144-152 and C-terminal end of the Helix 2. Our analysis of results obtained from MD simulation clearly shows that this long-range effect plays an important role in the conformational fluctuations in mutant structures of human prion protein. Results obtained from molecular modeling such as creation or elimination of some hydrogen bonds, increase or decrease of the accessible surface area and molecular surface, loss or accumulation of negative or positive charges on specific positions, and altering the polarity and pKa values, show that amino acid point mutations, though not urgently change the stability of PrP, might have some local impacts on the protein interactions which are required for oligomerization into fibrillar species.     

Evidence that TNF-β (lymphotoxin α) can activate the inflammatory environment in human chondrocytes

Introduction

Inflammatory cytokines play a key role in the pathogenesis of joint diseases such as rheumatoid arthritis (RA). Current therapies target mainly tumor necrosis factor α (TNF-α) as this has proven benefits. However, a large number of patients do not respond to or become resistant to anti-TNF-α therapy. While the role of TNF-α in RA is quite evident, the role of TNF-β, also called lymphotoxin-α (LT-α), is unclear. In this study we investigated whether TNF-β and its receptor play a role in chondrocytes in the inflammatory environment.

Methods

An in vitro model of primary human chondrocytes was used to study TNF-β-mediated inflammatory signaling.

Results

Cytokine-induced inflammation enhances TNF-β and TNF-β-receptor expression in primary human chondrocytes accompanied by the up-regulation of inflammatory (cyclooxygenase-2), matrix degrading (matrix metalloproteinase-9 and -13) and apoptotic (p53, cleaved caspase-3) signaling pathways, all known to be regulated by NF-κB. In contrast, anti-TNF-β, similar to the natural NF-κB inhibitor (curcumin, diferuloylmethane) or the knockdown of NF-κB by using antisense oligonucleotides (ASO), suppressed IL-1β-induced NF-κB activation and its translocation to the nucleus, and abolished the pro-inflammatory and apoptotic effects of IL-1β. This highlights, at least in part, the crucial role of NF-κB in TNF-β-induced-inflammation in cartilage, similar to that expected for TNF-α. Finally, the adhesiveness between TNF-β-expressing T-lymphocytes and the responding chondrocytes was significantly enhanced through a TNF-β-induced inflammatory microenvironment.

Conclusions

These results suggest for the first time that TNF-β is involved in microenvironment inflammation in chondrocytes during RA parallel to TNF-α, resulting in the up-regulation of NF-κB signaling and activation of pro-inflammatory activity.     

A Proline/Arginine-Rich End Leucine-Rich Repeat Protein (PRELP) Variant Is Uniquely Expressed in Chronic Lymphocytic Leukemia Cells

Proline/arginine-rich end leucine-rich repeat protein (PRELP) belongs to the small leucine-rich proteoglycan (SLRP) family, normally expressed in extracellular matrix of collagen-rich tissues. We have previously reported on another SLRP, fibromodulin (FMOD) in patients with chronic lymphocytic leukemia (CLL). PRELP is structurally similar to FMOD with adjacent localization on chromosome 1 (1q32.1). As cluster-upregulation of genes may occur in malignancies, the aim of our study was to analyze PRELP expression in CLL. PRELP was expressed (RT-PCR) in all CLL patients (30/30), as well as in some patients with mantle cell lymphoma (3/5), but not in healthy donor leukocytes (0/20) or tumor samples from other hematological malignancies (0/35). PRELP was also detected in CLL cell-lines (4/4) but not in cell-lines from other hematological tumors (0/9). PRELP protein was detected in all CLL samples but not in normal leukocytes. Deglycosylation experiments revealed a CLL-unique 38 kDa core protein, with an intact signal peptide. This 38 kDa protein was, in contrast to the normal 55 kDa size, not detected in serum which, in combination with the uncleaved signal peptide, suggests cellular retention. The unique expression of a 38 kDa PRELP in CLL cells may suggest involvement in the pathobiology of CLL and merits further studies.     

Curcumin Chemosensitizes 5-Fluorouracil Resistant MMR-Deficient Human Colon Cancer Cells in High Density Cultures

Objective

Treatment of colorectal cancer (CRC) remains a clinical challenge, as more than 15% of patients are resistant to 5-Fluorouracil (5-FU)-based chemotherapeutic regimens, and tumor recurrence rates can be as high as 50–60%. Cancer stem cells (CSC) are capable of surviving conventional chemotherapies that permits regeneration of original tumors. Therefore, we investigated the effectiveness of 5-FU and plant polyphenol (curcumin) in context of DNA mismatch repair (MMR) status and CSC activity in 3D cultures of CRC cells.

Methods

High density 3D cultures of CRC cell lines HCT116, HCT116+ch3 (complemented with chromosome 3) and their corresponding isogenic 5-FU-chemo-resistant derivative clones (HCT116R, HCT116+ch3R) were treated with 5-FU either without or with curcumin in time- and dose-dependent assays.

Results

Pre-treatment with curcumin significantly enhanced the effect of 5-FU on HCT116R and HCR116+ch3R cells, in contrast to 5-FU alone as evidenced by increased disintegration of colonospheres, enhanced apoptosis and by inhibiting their growth. Curcumin and/or 5-FU strongly affected MMR-deficient CRC cells in high density cultures, however MMR-proficient CRC cells were more sensitive. These effects of curcumin in enhancing chemosensitivity to 5-FU were further supported by its ability to effectively suppress CSC pools as evidenced by decreased number of CSC marker positive cells, highlighting the suitability of this 3D culture model for evaluating CSC marker expression in a close to vivo setting.

Conclusion

Our results illustrate novel and previously unrecognized effects of curcumin in enhancing chemosensitization to 5-FU-based chemotherapy on DNA MMR-deficient and their chemo-resistant counterparts by targeting the CSC sub-population. (246 words in abstract).