Characterization of glycopeptides, aminoglycosides and macrolide resistance among Enterococcus faecalis and Enterococcus faecium isolates from hospitals in Tehran

The prevalence of glycopeptides, aminoglycosides and erythromycin resistance among Enterococcus faecalis and Enterococcus faecium was investigated. The susceptibility of 326 enterococcal hospital isolates to amikacin, kanamycin, netilmicin and tobramycin were determined using disk diffusion method. The minimum inhibitory concentration (MIC) of vancomycin, teicoplanin, gentamicin, streptomycin, and erythromycin were determined by microbroth dilution method. The genes encoding aminoglycoside modifying enzymes described as AMEs genes, erythromycin-resistant methylase (erm) and vancomycin-resistant were targeted by multiplex-PCR reaction. High level resistance (HLR) to gentamicin and streptomycin among enterococci isolates were 52% and 72% respectively. The most prevalent of AMEs genes were aac (6')-Ie aph (2") (63%) followed by aph (3')-IIIa (37%). The erythromycin resistance was 45% and 41% of isolates were positive for ermB gene. The ermA gene was found in 5% of isolates whereas the ermC gene was not detected in any isolates. The prevalence of vancomycin resistant enterococci (VRE) was 12% consisting of E. faecalis (6%) and E. faecium (22%) and all of them were VanA Phenotype. The results demonstrated that AMEs, erm and van genes are common in enterococci isolated in Tehran. Furthermore our results show an increase in the rate of vancomycin resistance among enterococci isolates in Iran.     

Enhanced Thermal Stability and Biocompatibility of Gold Nanorods by Graphene Oxide

In the present study, the effect of nanosized graphene oxide layer on thermal stability and biocompatibility of gold nanorods has been examined. The graphene oxide-wrapped gold nanorods were prepared by electrostatic interaction between negatively charged graphene oxide and positively charged nanorods. The resulting nanohybrids were then heated at different time intervals to 95 °C in a water bath to assess the effect of heat on the rods morphology. The structural changes in gold nanorods were monitored via UV-Vis spectroscopy measurements and transmission electron microscopy images. In similar experiments, the graphene oxide used to wrap gold nanorods was reduced by ascorbic acid in a 95 °C water bath. Our results indicate that while bare gold nanorods are highly vulnerable to elevated temperatures, graphene oxide and reduced graphene oxide-coated gold nanorods remain thermally stable with no structural changes. We also confirmed that the enhanced thermal stability is highly dependent on the concentration of deposited graphene oxide available on the surface of the gold nanorods. In addition, we performed an MTT (3-[4,5-dimethylthiazol-2yl]-2,5-diphenyltetrazoliumbromide) assay to make a comparison between the cytotoxicity of the nanohybrids and their primary building blocks on human dermal fibroblast cells as a normal cell line. We found evidence that graphene oxide can enhance the biocompatibility of the rods through covering toxic chemicals on the surface of them.

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Comparative mRNA/micro-RNA co-expression network drives melanomagenesis by promoting epithelial–mesenchymal transition and vasculogenic mimicry signaling

This study aimed to identify a novel disease-associated differentially co-expressed mRNA-microRNA (miRNA) that is associated with vasculogenic mimicry (VM) and epithelial-to-mesenchymal transition (EMT) network at different stages of melanoma. By applying weighted gene co-expression network analysis, we constructed a VM+EMT biological network with the available microarray dataset downloaded from a public database. Quantitative real-time PCR, immunohistochemical staining, and CD31-periodic acid solution dual staining were performed to confirm the expression of genes associated with EMT and VM formation in subjects with malignant melanoma (n = 18) and primary melanoma (n = 13) and in healthy subjects (n = 10). Our findings suggested that phosphatidylserine-specific phospholipase A1-alpha (PLA1A) and dermokine (DMKN) genes function as oncogenes that trigger VM and EMT processes during melanomagenesis on interaction with miR-370, miR-563, and miR-770–5p. PLA1A and DMKN genes can be considered potential VM+EMT network-based diagnostic biomarkers for distinguishing between melanoma patients. We postulate that a network with altered PLA1A/miR-563 and DMNK/miR-770–5p/miR-370 may contribute to melanomagenesis by triggering the EMT signaling pathway and VM formation. This study provides a potentially valuable approach for the early diagnosis and prognosis of melanoma progression.     

Investigation of the binding interactions of Bisdemethoxycurcumin,Diacetylcurcumin and Diacetylbisdemethoxycurcumin with bovine α-lactalbumin by experimental and theoretical analysis

It was reported that bovine α-lactalbumin (BLA) as an important whey protein can be utilized as valuable vehicle for metal ions. The goal of this study was to investigate the interaction of BLA with bisdemethoxycurcumin (BDMC), Diacetylcurcumin (DAC), and diacetylbisdemethoxycurcumin (DABC) as three bioactive compounds by fluorescence quenching measurements and docking studies. It was observed that these ligands come closer to tryptophan residues and quench their emission without any change in their micro region polarity. The Stern–Volmer equation which is the best model to provide information about the interaction between small bioactive molecules and proteins was used to obtain the binding constants and the binding stoichiometry. Information about the extent of resonance energy transfer and Förster’s distance between donor and acceptor was estimated. Thermodynamic parameters confirmed that the final BDMC–BLA complex was stabilized by hydrogen bonds, whereas the final DABC–BLA and DAC–BLA complexes were stabilized by hydrophobic bonds which are in accordance with their chemical structures. Both the synchronous and docking studies verified that theTrp-26 which is the most exposed Tryptophan residue has the most contribution in the binding process. The Förster’s distances between bound ligands and tryptophans were in agreement with the measured distances by docking studies. The obtained achievements confirmed that there are considerable binding interactions between these curcuminoids and BLA.     

Two different 1D-chains in the structures of the copper(I) coordination polymers based on bidentate Schiff-base building units and thiocyanate anions as bridging ligands

The reaction of the bidentate Schiff-base ligands (3,4,5-MeO-ba)₂en (L¹) and (4-Me-ba)₂en (L²) with Cu(SCN) in CH₃CN yielded two copper(I) coordination polymers [Cu(L¹)(SCN)]_n (1) and [Cu(L²)(SCN)]_n (2), which have been characterized by elemental analyses, IR- and ¹H NMR-spectroscopy, and X-ray crystallography. The non-centrosymmetric structures of both Cu(I) complexes consist of an one-dimensional polymeric chain in which copper(I) ions are bridged by two thiocyanate groups bonding in an end-to-end fashion. The Cu(I)?Cu(I) separation is 5.604 Å in 1 and 5.706 Å in 2.     

3D QSAR studies,pharmacophore modeling,and virtual screening of diarylpyrazole–benzenesulfonamide derivatives as a template to obtain new inhibitors,using human carbonic anhydrase II as a model protein

A 3D-QSAR modeling was performed on a series of diarylpyrazole-benzenesulfonamide derivatives acting as inhibitors of the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1). The compounds were collected from two datasets with the same scaffold, and utilized as a template for a new pharmacophore model to screen the ZINC database of commercially available derivatives. The datasets were divided into training, test, and validation sets. As the first step, comparative molecular field analysis (CoMFA), CoMFA region focusing and comparative molecular similarity indices analysis (CoMSIA) in parallel with docking studies were applied to a set of 41 human (h) CA II inhibitors. The validity and the prediction capacity of the resulting models were evaluated by leave-one-out (LOO) cross-validation approach. The reliability of the model for the prediction of possibly new CA inhibitors was also tested.     

The Effect of Bumpy Structure on Optical Properties of Bimetallic Nanoshells

In this paper, a sensitive bumpy bimetallic nanoshell for detection of thyroid cancer market (Thyroglobulin, Tg) and bovine serum albumin (BSA) proteins is reported. The physical origin of plasmonic properties of bimetal nanoshells is described by plasmon hybridization theory which indicates three intense and clearly separated plasmon modes. The electric field intensity enhancement of the bumpy bimetal nanoshell increases by ~559 %, at the surface of the bump in comparison with a smooth shell. The presence of bumpy structure on the nanoshell surface provides a high enhancement of the resulting Raman signal through an electromagnetic field of the order of 10⁷ which leads to an increase in sensitivity detection of Tg and BSA proteins. In addition, a refractive index (RI) sensitivity of 332.54 nm/RIU is achieved for this bumpy bimetallic nanoshell.     

Galactosylated collagen matrix enhanced in vitro maturation of human embryonic stem cell-derived hepatocyte-like cells

Due to their important biomedical applications, functional human embryonic stem cell-derived hepatocyte-like cells (hESC-HLCs) are an attractive topic in the field of stem cell differentiation. Here, we have initially differentiated hESCs into functional hepatic endoderm (HE) and continued the differentiation by replating them onto galactosylated collagen (GC) and collagen matrices. The differentiation of hESC-HE cells into HLCs on GC substrate showed significant up-regulation of hepatic-specific genes such as ALB, HNF4α, CYP3A4, G6P, and ASGR1. There was more albumin secretion and urea synthesis, as well as more cytochrome p450 activity, in differentiated HLCs on GC compared to the collagen-coated substrate. These results suggested that GC substrate has the potential to be used for in vitro maturation of hESC-HLCs.     

Salicylic acid affects growth,essential oil and chemical compositions of thyme (Thymus daenensis Celak.) under reduced irrigation

Salicylic acid (SA) may reduce the negative impact of water deficit on growth and metabolite yield of Thymus daenensis Celak subsp. daenensis Celak. The effect of foliar application of SA and reduced irrigation on growth, oil yield, chemical components, and antibacterial and antioxidant activities of T. daenensis in field condition were investigated. Treatments comprised 0.0, 1.5 and 3.0 M SA applied to plants under normal irrigation and stressed conditions. Results indicated that irrigation regime had a significant effect on growing degree days (GDD) required to reach early and full flowering. Foliar application of SA influenced GDD from early growing stage to 50 % and full flowering, minimum radius and canopy diameter. The highest values of oil content (3.2 % v/w) and yield (14.9 g m^?2) were obtained from application of 3.0 M SA. Percentage of some chemical constituents in the essential oil extracted from the plants under stress was higher than non-stressed plants. Thymol content was significantly reduced under stressed conditions. Foliar application of SA significantly improved carvacrol, α-thujene, α-pinene and p-cymene contents in the oils, but reduced thymol and, β-caryophyllene amounts. Our results showed that foliar application of SA reduced the negative effect of water deficit on thymol content in the essential oil of T. daenensis. The essential oils of T. daenensis exhibited antioxidant and antibacterial activities when plants were sprayed with 1.5 and 3.0 M SA, respectively.     

A nonlinear homogenized finite element analysis of the primary stability of the bone–implant interface

Stability of an implant is defined by its ability to undergo physiological loading–unloading cycles without showing excessive tissue damage and micromotions at the interface. Distinction is usually made between the immediate primary stability and the long-term, secondary stability resulting from the biological healing process. The aim of this research is to numerically investigate the effect of initial implantation press-fit, bone yielding, densification and friction at the interface on the primary stability of a simple bone–implant system subjected to loading–unloading cycles. In order to achieve this goal, human trabecular bone was modeled as a continuous, elasto-plastic tissue with damage and densification, which material constants depend on bone volume fraction and fabric. Implantation press-fit related damage in the bone was simulated by expanding the drilled hole to the outer contour of the implant. The bone–implant interface was then modeled with unilateral contact with friction. The implant was modeled as a rigid body and was subjected to increasing off-axis loading cycles. This modeling approach is able to capture the experimentally observed primary stability in terms of initial stiffness, ultimate force and progression of damage. In addition, it is able to quantify the micromotions around the implant relevant for bone healing and osseointegration. In conclusion, the computationally efficient modeling approach used in this study provides a realistic structural response of the bone–implant interface and represents a powerful tool to explore implant design, implantation press-fit and the resulting risk of implant failure under physiological loading.