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21.
The cancer stem cell (CSC) model encompasses an advantageous paradigm that in recent decades provides a better elucidation for many important biological aspects of cancer initiation, progression, metastasis, and, more important, development of multidrug resistance (MDR). Such several other hematological malignancies and solid tumors and the identification and isolation of ovarian cancer stem cells (OV-CSCs) show that ovarian cancer also follows this hierarchical model. Gaining a better insight into CSC-mediated resistance holds promise for improving current ovarian cancer therapies and prolonging the survival of recurrent ovarian cancer patients in the future. Therefore, in this review, we will discuss some important mechanisms by which CSCs can escape chemotherapy, and then review the recent and growing body of evidence that supports the contribution of CSCs to MDR in ovarian cancer.  相似文献   
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23.

We are proposing graphene (G)-based multilayered plasmonic spatial switch, operating at 10 THz. It is composed of hBN/Ag/hBN/G/hBN/G/hBN/SiO2/p+-Si multilayers. When a 10-THz transverse magnetic (TM)-polarized signal is normally incident upon the structure top surface, the nanoaperture devised in the Ag nanolayer, acting as a grating, excites surface plasmons at the top graphene micro-ribbons/hBN interface. These surface plasmons depending on the graphenes chemical potentials can be coupled to the lower-right or left graphene micro-ribbons and continue to propagate laterally towards the corresponding output port. Numerical simulations show that a change of ∆VG ≈ ± 2.7 V in the voltage, applied to the gated micro-ribbons, can modulate their chemical potentials sufficiently to switch the right (left) output port from ON (OFF) to OFF(ON) and vice versa. Besides its low power consumption, the switch ultra-small dimensions make it a potential spatial router suitable for THz-integrated circuit applications.

  相似文献   
24.
Plant Cell, Tissue and Organ Culture (PCTOC) - In the present study, the integrative effects of two sets of stress tolerance-inducing and stress-inducing elicitors, including polyethylene...  相似文献   
25.
A series of 16 novel 1,2,4-triazine derivatives bearing hydrazone moiety (7a7p) have been designed, synthesized and evaluated for their activity to inhibit IL-1β and TNF-α production. All compounds are reported for the first time. The chemical structures of all compounds were confirmed by spectroscopic methods and elemental analyzes. Most of the synthesized compounds were proved to have potent anti-cytokine activity and low toxicity on PBMC and MCF-7 cell lines. Compounds 7f, 7k, 7l and 7j presented simultaneously good levels of inhibition of both cytokines. Moreover, compound 7l exhibited good anti-inflammatory effect in carrageenan-induced rat paw edema. The results of Western blotting demonstrated that the anti-cytokine potential of compound 7l is mainly mediated through the inhibition of p38 MAPK signaling pathway. Molecular docking was performed to position compound 7l into p38α binding site in order to explore the potential target. The information of this work might be helpful for the design and synthesis of novel scaffold toward the development of new therapeutic agent to fight against inflammatory diseases.  相似文献   
26.

Background

Olive trees (Olea europaea subsp. europaea var. europaea) naturally grow in areas spanning the Mediterranean basin and towards the East, including the Middle East. In the Iranian plateau, the presence of olives has been documented since very ancient times, though the early history of the crop in this area is shrouded in uncertainty.

Methods

The varieties presently cultivated in Iran and trees of an unknown cultivation status, surviving under extreme climate and soil conditions, were sampled from different provinces and compared with a set of Mediterranean cultivars. All samples were analyzed using SSR and chloroplast markers to establish the relationships between Iranian olives and Mediterranean varieties, to shed light on the origins of Iranian olives and to verify their contribution to the development of the current global olive variation.

Results

Iranian cultivars and ecotypes, when analyzed using SSR markers, clustered separately from Mediterranean cultivars and showed a high number of private alleles, on the contrary, they shared the same single chlorotype with the most widespread varieties cultivated in the Mediterranean.

Conclusion

We hypothesized that Iranian and Mediterranean olive trees may have had a common origin from a unique center in the Near East region, possibly including the western Iranian area. The present pattern of variation may have derived from different environmental conditions, distinct levels and selection criteria, and divergent breeding opportunities found by Mediterranean and Iranian olives.These unexpected findings emphasize the importance of studying the Iranian olive germplasm as a promising but endangered source of variation.  相似文献   
27.
Protozoan pathogens that cause leishmaniasis in humans are relatively refractory to genetic manipulation. In this work, we implemented the CRISPR‐Cas9 system in Leishmania parasites and demonstrated its efficient use for genome editing. The Cas9 endonuclease was expressed under the control of the Dihydrofolate Reductase‐Thymidylate Synthase (DHFR‐TS) promoter and the single guide RNA was produced under the control of the U6snRNA promoter and terminator. As a proof of concept, we chose to knockout a tandemly repeated gene family, the paraflagellar rod‐2 locus. We were able to obtain null mutants in a single round of transfection. In addition, we confirmed the absence of off‐target editions by whole genome sequencing of two independent clones. Our work demonstrates that CRISPR‐Cas9‐mediated gene knockout represents a major improvement in comparison with existing methods. Beyond gene knockout, this genome editing tool opens avenues for a multitude of functional studies to speed up research on leishmaniasis.  相似文献   
28.
Cardiovascular diseases are the main cause of death globally. Many attempts have been done to ameliorate the pathological changes after the occurrence of myocardial infarction. Curcumin is touted as a polyphenol phytocompound with appropriate cardioprotective properties. In this study, the therapeutic effect of curcumin was investigated on acute myocardial infarction in the model of rats. Rats were classified into four groups; control, isoproterenol hydrochloride (ISO) (100 mg/kbw), curcumin (50 mg/kbw), and curcumin plus ISO treatment groups. After 9-day administration of curcumin, levels of lactate dehydrogenase (LDH), creatine kinase (CK), and cardiac troponin I (cTnI) were determined. Superoxide dismutase (SOD) and malondialdehyde (MDA) contents were measured to investigate the oxidative status in infarct rats received curcumin. By using H & E staining, tissue inflammation was performed. Masson’s trichrome staining was conducted to show cardiac remodeling and collagen deposition. The number of apoptotic cells was determined by using the terminal deoxynucleotidyl transferase dUTP nick end labeling assay. Data showed the serum decrease of LDH, CK, and cTnI in infarct rats after curcumin intake compared to the rats given (ISO) ( P < 0.05). Curcumin was found to reduce oxidative status by reducing SOD and MDA contents ( P < 0.05). Gross and microscopic examinations revealed that the decrease of infarct area, inflammation response and collagen deposition in rats given ISO plus curcumin ( P < 0.05). We noted the superior effect of curcumin to reduce the number of apoptotic cardiomyocytes after 9 days. Data point the cardioprotective effect of curcumin to diminish the complication of infarction by the reduction of cell necrosis and apoptosis in a rat model of experimental infarction.  相似文献   
29.
30.
A comparative biochemical and structural study was performed on a cold active α-amylase from Bacillus cereus (BCA) and two well-known homologous mesophilic and thermophilic α-amylases from Bacillus amyloliquefaciens (BAA) and Bacillus licheniformis (BLA). In spite of a high degree of sequence and structural similarity, drastic variations were found for Topt as 50, 70 and 90 °C for BCA, BAA and BLA, respectively. The half-lives of thermoinactivation were 1 and 9 min for BCA and BAA at 80 °C respectively, whilst there was no inactivation for BLA at this temperature. Thermodynamic studies on inactivation process suggested that lower thermostability of BCA is due to lower inactivation slope of the Arrhenius plots and subsequently, lower Ea and ΔH#. Increased Km and accessible surface area for catalytic residues along with a decreased number of internal interactions in this region in BCA compared to BLA suggest that BCA substrate-binding site might be temperature sensitive and is probably more flexible. On the other hand, fewer ion pairs, destructive substitutions and disruption of aromatic interaction networks in structurally critical regions of Bacillus α-amylases result in a severe decrease in BCA thermostability compared to its mesophilic and thermophilic homologues.  相似文献   
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