A new look at the modified Coulomb potential in a strong magnetic field

The static Coulomb potential of Quantum Electrodynamics (QED) is calculated in the presence of a strong magnetic field in the lowest Landau level (LLL) approximation using two different methods. First, the vacuum expectation value of the corresponding Wilson loop is calculated perturbatively in two different regimes of dynamical mass $m_{dyn.}$, {\it i.e.}, $|{\mathbf{q}}_{\|}^{2}|\ll m_{dyn.}^{2}\ll |eB|$ and $m_{dyn.}^{2}\ll |\mathbf{q}_{\|}^{2}|\ll|eB|$, where $\mathbf{q}_{\|}$ is the longitudinal components of the momentum relative to the external magnetic field $B$. The result is then compared with the static potential arising from Born approximation. Both results coincide. Although the arising potentials show different behavior in the aforementioned regimes, a novel dependence on the angle $\theta$ between the particle-antiparticle's axis and the direction of the magnetic field is observed. In the regime $|{\mathbf{q}}_{\|}^{2}|\ll m_{dyn.}^{2}\ll |eB|$, for strong enough magnetic field and depending on the angle $\theta$, a qualitative change occurs in the Coulomb-like potential; Whereas for $\theta=0,\pi$ the potential is repulsive, it exhibits a minimum for angles $\theta\in]0,\pi[$.Comment: V1: 26 pages, 8 figures, latex format, V2: Accepted for publication in PRD (2007

The cytotoxic and migrastatic potentials of Allium Jesdianum hydroalcoholic extract on glioblastoma multiforme cell line model

OBJECTIVE: Glioblastoma multiforme is one of the most malignant types of central nervous system tumors and temozolomide (TMZ) is currently used as a standard treatment for this type of cancer. However, resistance to temozolomide is a problem in the successful treatment. Plants and herbs are potential sources of cancer therapeutics. This study aimed at evaluating the effect of Allium Jesdianum (AJ) hydroalcoholic extract on glioblastoma multiforme cells. MATERIALS AND METHODS: The plant material was purchased and extracted. The cell line was treated with extract for 24, 48, and 72 hr. Cell viability was assessed by trypan blue staining, MTT assay, and lactate dehydrogenase activity measurement. Tumor invasion potential was evaluated by cell migration, invasion, and adhesion tests. Real-time PCR was used to assess the changes in the expression pattern of genes involved in cancer invasion. RESULTS: Extract treatment caused a concentration- and time-dependent decrease in cell survival. Also, a decrease in cell migration, invasion and adhesion potential and the expression of metalloproteinases 2 and 9 in cells was observed after treatment. CONCLUSIONS: Allium Jesdianum showed promising anti-cancer activity in glioblastoma multiforme cells

The effect of Pogostone on viability, membrane integrity, and apoptosis of liver cancer cells

OBJECTIVE: The incidence of liver cancer is still high in many countries, including Iran. Drug resistance and various side effects are the main obstacles to treating this cancer. Herbs, which are traditionally used, are now widely regarded as treatment options for cancer. Pogostone is a natural substance isolated from Indian mint (Pogostemon cablin) and has various medicinal activities. This study aimed to determine the effect of Pogostone on liver cancer cell line (viability, membrane integrity, and apoptosis). MATERIALS AND METHODS: The liver cancer cell line was prepared from Pasteur Institute of Iran and treated with appropriate concentrations of Pogostone. Cytotoxicity was determined by MTT, trypan blue, and lactate dehydrogenase assay. Apoptosis induction was evaluated by diphenylamine assay, Annexin V-FITC staining and a Real-time PCR test. Data were analyzed by SPSS statistical software using Tukey’s test one-way analysis of variance. RESULTS: After all three time periods, a significant decrease in viability was observed (p <0.05) in a concentration- and time-dependent manner. The cytotoxicity of Pogostone to liver cancer cells was in a concentration- and time-dependent manner. Pogostone significantly induced apoptosis compared to control cells (p<0.05). Treatment of liver cancer cells with Pogostone significantly reduced Bcl-2 gene expression (p<0.05). On the other hand, expression of all three Bax, p53, and caspase 3 genes showed a significant increase after treatment (p<0.05). CONCLUSIONS: Pogostone had a concentration- and time-dependent toxic effect on liver cancer cells. It induced apoptosis by increasing the Bax to Bcl-2 ratio

CXCL12-CXCR4 axis: its role and the drug inhibitors on each type of cancers

Objective: Chemokine 12, C-X-C Motif Chemokine Ligand 12 (CXCL12), and its receptor C-X-C Motif Chemokine Ligand 4 (CXCR4), both play essential and critical roles in the development of different types of cancers. Almost, in all of the cancers, overexpression of these two chemokines is a key to diagnose of cancers and lead them to progress, an increment in proliferation, the invasive feature of different cell lines, metastasis, and a noticeable decrement in apoptosis. Although the impact of this axis on cancer development is known and investigated, there was no review article about this molecular pathway and the drug effects on this cascade is not written. In this regard, we probed the researches about this intracellular process and the drugs that are useful for suppressing it on one-by-one cancer. Materials and Methods: We reviewed this study with scientific keywords in ScienceDirect, Google Scholar, and PubMed. Our research process was to review every study that has looked at this process in every cancer, as well as the drugs selected to treat cancer from 14 years ago onwards. Results: Our researches showed that there are some inhibitors that are introduced in order to block the pathway in many cancers. In addition, the data related to the effect of this pathway on some types of cancers are not enough. Conclusions: Summing up, the present study clears a route to suppress the invasion of cancers and bold the tips that have not been worked on yet

Anti-invasion and anti-metastasis effects of Dandelion (Taraxacum officinale) hydroalcoholic extract on glioblastoma multiforme cell line model

OBJECTIVE: Glioblastoma multiforme is one of the malignant brain tumors and despite recent advancements in cancer treatment remains largely incurable. Cancer invasion has a cascade of interrelated and sequential steps, including cell adhesion, extracellular matrix degradation, and cell movement. Hence, inhibition of the invasion-associated steps could be a potential strategy for prolonging the life of patients. This study aimed to evaluate the anti-invasion and anti-metastasis effects of Dandelion (Taraxacum officinale) hydro-alcoholic extract on glioblastoma multiforme cell line (U87MG). MATERIALS AND METHODS: The hydro-alcoholic extract was prepared, and the cell line was treated with 1000, 500, 250, 125, and 62.5 µg / ml of extract for 24, 48, and 72 hr. Cell viability was evaluated. The effect of extract (IC50 concentration) on cancer cell invasion potential was tested. The expression levels of MMP-2, MMP-9, TIMP-1, TIMP-2, uPA, uPAR, p38MAPK, ERK1/2, and SAPK/JNK were analyzed. Comparisons between groups were performed by Tukey’s test one-way analysis of variance and differences were considered significant when p < 0.05. RESULTS: After treatment with extract, the cells viability was decrease in a concentration- and time-dependent. IC50 concentration of dandelion extract significantly decreased the cell migration by 32% (p<0.05), cell invasion potential by 77% (p<0.05) and cell adhesion by 51% (p<0.05). Also, the expression levels of proteolytic enzymes associated with matrix and base membrane degradation (MMP-2, MMP-9, and uPA) were decreased and the levels of their endogenous inhibitors (TIMP1 and TIMP2) were increased. Moreover, the p38MAPK and SAPK/JNK signaling pathway, which stimulates proteolytic enzymes and matrix degradation, was inhibited by extract treatment. CONCLUSIONS: Dandelion extract reduced the viability and invasion potential of the glioblastoma cells by regulating proteolytic enzymes and matrix dynamics through the p38MAPK and SAPK/JNK pathway

Pogostone effect on dacarbazine-induced autophagy and apoptosis in human melanoma cells

Objective: Chemotherapy is effective for treating malignant melanoma, but drug resistance and occurrence of side effects limited this strategy. The balance between autophagy and apoptosis has an essential role in the chemotherapy of cancers. The present investigation aims to examine the efficacy of pogostone (isolated from Pogostemon cablin L.) on the ratio of apoptosis and autophagy caused by dacarbazine in melanoma cells. Materials and Methods: Human melanoma cells were exposed to different concentrations of dacarbazine and pogostone, and the IC50 values were calculated. The cells were treated with two concentrations higher and lower than IC50 simultaneously, and the dose reduction index and combination index (CI) parameters were calculated. The occurrence of apoptosis and autophagy was evaluated. The expression level of genes related to apoptosis and autophagy pathways was tested. Results: Pogostone and dacarbazine declined the number of the cells in a dose and time-dependent manner and showed a synergistic effect. There was a significant decrease in autophagy in the co-treatment besides the dacarbazine alone (p < 0.05). There was a considerable increment in apoptosis in cultures treated with pogostone and dacarbazine (p < 0.05). Also, Real-time PCR data confirmed the obtained results. Conclusions: Pogostone reduced melanoma cell resistance to dacarbazine via autophagy blockage

Anti-proliferative and apoptotic effects of Rosa canina fruit extract on thyroid cancer cells (B-CPAP and Thr.C1-PI 33)

OBJECTIVE: Thyroid cancer is one of the most common endocrine malignancies. Although most thyroid cancers respond to surgery and treatment, drug-resistant is a problem that necessitates new therapeutic strategies. Rosa canina from the Rosaceae family is suggested as an herbal remedy for numerous human ailments. Due to the need to identify new therapies for thyroid cancer and due to the therapeutic properties of Rosa canina, this study aimed to investigate the effect of Rosa canina fruit extract on two thyroid cancer cell lines (B-CPAP and Thr.C1-PI 33). MATERIALS AND METHODS: After preparation of hydro-alcoholic extract of Rosa canina fruits and treatment of thyroid cancer cells, the cell survival, and proliferation were evaluated. Apoptosis cell death and nitric oxide production were estimated. Real-time PCR was used to investigate the expression of apoptosis-related genes. Statistical evaluation was performed using one-way analysis of variance (ANOVA) and differences were considered not significant when p > 0.05. RESULTS: The extract reduced the viability of the cells in a concentration- and time-dependent manner. Nitric oxide production was decreased in a concentration- and time-dependent manner. The extract stimulated apoptosis cell death by decreasing the expression of Bcl-2 and increasing the expression of Bax, p53, and Caspase 3. CONCLUSIONS: This extract can be promising in the treatment of patients with thyroid cancer

EEG-Based Functional Brain Networks: Does the Network Size Matter?

Functional connectivity in human brain can be represented as a network using electroencephalography (EEG) signals. These networks – whose nodes can vary from tens to hundreds – are characterized by neurobiologically meaningful graph theory metrics. This study investigates the degree to which various graph metrics depend upon the network size. To this end, EEGs from 32 normal subjects were recorded and functional networks of three different sizes were extracted. A state-space based method was used to calculate cross-correlation matrices between different brain regions. These correlation matrices were used to construct binary adjacency connectomes, which were assessed with regards to a number of graph metrics such as clustering coefficient, modularity, efficiency, economic efficiency, and assortativity. We showed that the estimates of these metrics significantly differ depending on the network size. Larger networks had higher efficiency, higher assortativity and lower modularity compared to those with smaller size and the same density. These findings indicate that the network size should be considered in any comparison of networks across studies

TMop: a Tool for Unsupervised Translation Memory Cleaning

We present TMop, the first open-source tool for automatic Translation Memory (TM) cleaning. The tool implements a fully unsupervised approach to the task, which allows spotting unreliable translation units (sentence pairs in different languages, which are supposed to be translations of each other) without requiring labeled training data. TMop includes a highly configurable and extensible set of filters capturing different aspects of translation quality. It has been evaluated on a test set composed of 1,000 translation units (TUs) randomly extracted from the English-Italian version of MyMemory, a large-scale public TM. Results indicate its effectiveness in automatic removing “bad” TUs, with comparable performance to a state-of-the-art supervised method (76.3 vs. 77.7 balanced accuracy)