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Signatures of Through-Space Charge Transfer in Two-Photon Absorption of Paracyclophane Derivatives
Abbas Salimi,조대흠,이진용,강선우,Shaul Mukamel 대한화학회 2019 Bulletin of the Korean Chemical Society Vol.40 No.11
Third order polarizability, (?) taken from the collective electronic oscillator (CEO) method was used to calculate the two-photon absorption (TPA) of tetrastyryl-[2,2]paracyclophane derivatives with different through-space charge transfer configurations considering various donor and acceptor combinations at the terminal styryl groups. For the virtually same linear absorption, different TPA spectra were obtained. For controlling and fine-tuning frequency and cross-sections of TPA the through-space charge transfer interactions can be used. The results are explained by the electronic density matrices corresponding to governing oscillators in one- and two-photon absorption and the ground state. It is indicated that for the studied systems mainly the lowest four oscillators are responsible for the TPA cross-sections rather than a simple effective three-state model.
Salimi, Abbas,Li, Hao,Shi, Hu,Lee, Jin Yong Elsevier 2019 Biochimica et biophysica acta, General subjects Vol.1863 No.5
<P><B>Abstract</B></P> <P>Amyloid-beta protein (Aβ) accumulation in the brain, which is influenced by several factors, is a hallmark of Alzheimer's disease (AD). Despite the important role of histidine in stabilizing the fibrillar structure of the Aβ peptide at neutral pH, the effect of histidine tautomerism on Aβ peptide aggregation is still largely unknown. Histidine is in equilibrium between δ and ε tautomers and there are three histidine residues (H6, H13, and H14) in the Aβ(1–40) peptide. We performed molecular dynamics simulation on (δδδ) and (εεε) histidine tautomers with different initial homodimeric configurations to elucidate structural and aggregation features. Results indicate that (εεε) homodimers have very low propensity or almost no tendency to form β-sheets, whereas (δδδ) dimers predominantly form β-sheets due to interactions between central hydrophobic core (CHC) residues and C-terminal residues. β-sheet formation occurred in the same regions of each dimer chain at the CHC and C-/N- terminals for different configurations of (δδδ). These results suggest that (δδδ) has an important role in AD progression. Our study provides deeper insight into the effect of tautomerism of histidine residues in Aβ(1–40) on amyloid aggregation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> (εεε) tautomers show low propensity to form β-sheets during homodimerization. </LI> <LI> (δδδ) tautomers show high β-sheets amount during homodimerization. </LI> <LI> (δδδ) tautomers may play more important role than (εεε) in Alzheimer. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
The histologic features of intratubular germ cell neoplasia and its correlation with tumor behavior
Abbas Basiri,Saeed Movahhed,Mahmood Parvin,Maziar Salimi,Gholam Hossein Rezaeetalab 대한비뇨의학회 2016 Investigative and Clinical Urology Vol.57 No.3
Purpose: To assess the prevalence of intratubular germ cell neoplasia (ITGCN) in patients with concurrent testis tumor and its correlation with histologic features and serum tumor markers. Materials and Methods: From 2003 to 2015, 179 patients underwent radical orchiectomy due to testicular mass. Tissue specimens were evaluated by an expert uro-pathologist using immunohistochemistry (IHC) staining, in addition to light microscopy, to identify presence of ITGCN. Patients' demographic characteristics, histologic subtypes, pathologic stage of tumor and serum tumor markers were gathered and analyzed. Results: Eighty-five out of 179 patients (47.5%) had concomitant ITGCN according to IHC staining. There was not statistically significant difference in histologic type, histologic components, cryptorchidism, and lymphovascular invasion between the 2 groups (p=0.151, p=0.11, p=0.233, p=0.413, and p=0.14, respectively). The prevalence of ITGCN was significantly higher in patients with stage T2 and T3 of tumor than those with stage T1. Elevated serum alpha feto protein level is much common in patients with ITGCN (p<0.001). Conclusions: The prevalence of concurrent ITGCN in our region is lower than previous data from western countries. ITGCN is more common in higher tumor stages and is accompanied with elevated serum alpha feto protein levels before surgery. Presence of ITGCN in adjacent tissue may suggest a negative cancer behavior.
Mirmalek, Seyed Abbas,Jangholi, Ehsan,Jafari, Mohammad,Yadollah-Damavandi, Soheila,Javidi, Mohammad Amin,Parsa, Yekta,Parsa, Tina,Salimi-Tabatabaee, Seyed Alireza,Kolagar, Hossein Ghasemzadeh,Jalil, S Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.no.sup3
Breast cancer is the most common malignancy and also the second leading cause of cancer death among women and also in women that have a high mortality. Previous studies showed that magnesium (Mg) has cytotoxic effects on malignant cell lines. However, the anti-cancer effects of Mg on MCF-7 breast cancer cells are uncertain. This study was aimed at the comparison of the cytotoxic effect of Mg salt (MgCl2) and cisplatin on MCF-7 cells and fibroblasts (as normal cells). After treatment with various concentrations of MgCl2, and cisplatin as a positive control for 24 and 48 hours (h), cytotoxicity activity was measured by MTT assay. In addition, apoptosis was determined by annexin V/propidium iide assay. Both cisplatin and the MgCl2 exhibited dose-dependent cytotoxic effects in the MCF-7 cell line, although the LD50 of the Mg was significantly higher when compared to cispaltin ($40{\mu}g/ml$ vs. $20{\mu}g/ml$). Regarding annexin V/propidium results, treatment of MCF-7 cells with LD50 concentrations of cisplatin and Mg showed 59% and 44% apoptosis at 24h, respectively. Finally, the results indicated that Mg has cytotoxic effects on MCF-7 cells, but less than cisplatin as a conventional chemotherapeutic agent. However, regarding the side effects of chemotherapy drugs, it seems that Mg can be considered as a supplement for the treatment of breast cancer.
Tautomeric Effect of Histidine on the Structural Properties of Aβ40 heterodimers
( Li Hao ),( Salimi Abbas ),이진용 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1
Alzheimer’s disease (AD) is the most common form of dementia occurred in the elderly that affected more than 40 million people across the world resulting in enormous social and economic impact. The intrinsic origin of amyloid aggregation still remains to be considered. The aggregation mechanism affected by the tautomeric state (δ and ε) of histidine residues (H6, H13, and H14) was previously investigated in A β40 and Aβ42 monomers. Molecular dynamics simulation results show different aggregation trends in the different heterodimers formed by the (εεε) and other isomers. In the (εεε:δδδ) dimer, the highest β -sheet content was obtained in the (δδδ) chain, consistent with our previous studies that showed the (δδδ) monomer most easily form a β -sheet secondary structure in the monomer. Further analysis confirmed that the (εεε:δδδ) dimer is more likely to aggregate than other heterodimers. The current research helps to understand the pathology AD.
Insight into the histidine tautomerism effect on heterodimers of Aβ40
Li Hao,Salimi Abbas,Burnea Francis Kirby B.,Shi Hu,Lee Jin Yong 대한화학회 2021 Bulletin of the Korean Chemical Society Vol.42 No.11
The intrinsic origin of amyloid aggregation has been pursued as a new pathogenesis for Alzheimer’s disease (AD). The aggregation mechanisms influenced by histidine tautomerism were previously investigated in Aβ40 and Aβ42 monomers. In the present study, we focus on the structural properties of Aβ40 heterodimer under the influence of histidine. The results of molecular dynamics simulation detected different aggregation trends were detected in different heterodimers formed by the εεε isomer and other isomers. In the (εεε:δδδ) dimer, the highest β-sheet content was obtained in the δδδ chain, which is in agreement with our previous studies that δδδ monomer is the most easily formed β-sheet secondary structure in the monomer. Further analysis confirmed that (εεε:δδδ) dimers more easily aggregate into fibrils in comparison with other heterodimers. This research will help in understanding the tautomeric effect on Aβ heterodimers, thereby helping to figure out the pathogenesis of AD.