Armenian National Academy of Sciences

About: Armenian National Academy of Sciences is a government organization based out in Yerevan, Armenia. It is known for research contribution in the topics: Population & Laser. The organization has 4090 authors who have published 4042 publications receiving 40828 citations. The organization is also known as: Armenian National Academy of Sciences & NAS RA.

Molecular dynamics study of intermediate phase of long chain alkyl sulfonate/water systems.

Abstract: Using atomic level simulation we aimed to investigate various intermediate phases of the long chain alkyl sulfonate/water system. Overall, about 800 ns parallel molecular dynamics simulation study was conducted for a surfactant/water system consisting of 128 sodium pentadecyl sulfonate and 2251 water molecules. The GROMACS software code with united atom force field was applied. Despite some differences, the analysis of main structural parameters is in agreement with X-ray experimental findings. The mechanism of self-assembly of SPDS molecules was also examined. At T = 323 K we obtained both tilted fully interdigitated and liquid crystalline-like disordered hydrocarbon chains; hence, the presence of either gel phase that coexists with a lamellar phase or metastable gel phase with fraction of gauche configuration can be assumed. Further increase of temperature revealed that the system underwent a transition to a lamellar phase, which was clearly identified by the presence of fully disordered hydrocarbon chains. The transition from gel-to-fluid phase was implemented by simulated annealing treatment, and the phase transition point at T = 335 K was identified. The surfactant force field in its presented set is surely enabled to fully demonstrate the mechanism of self-assembly and the behavior of phase transition making it possible to get important information around the phase transition point.

Targeting Degradation of EGFR through the Allosteric Site Leads to Cancer Cell Detachment-Promoted Death

Abstract: Targeting epidermal growth factor receptor (EGFR) with tyrosine kinase inhibitors (TKI) has been widely exploited to disrupt aberrant phosphorylation flux in cancer. However, a bottleneck of potent TKIs is the acquisition of drug resistance mutations, secondary effects, and low ability to attenuate tumor progression. We have developed an alternative means of targeting EGFR that relies on protein degradation through two consecutive routes, ultimately leading to cancer cell detachment-related death. We describe furfuryl derivatives of 4-allyl-5-[2-(4-alkoxyphenyl)-quinolin-4-yl]-4H-1,2,4-triazole-3-thiol that bind to and weakly inhibit EGFR tyrosine phosphorylation and induce strong endocytic degradation of the receptor in cancer cells. The compound-promoted depletion of EGFR resulted in the sequestration of non-phosphorylated Bim, which no longer ensured the integrity of the cytoskeleton machinery, as shown by the detachment of cancer cells from the extracellular matrix (ECM). Of particular note, the longer CH3(CH2)n chains in the terminal moiety of the anti-EGFR molecules confer higher hydrophobicity in the allosteric site located in the immediate vicinity of the catalytic pocket. Small compounds accelerated and enhanced EGFR and associated proteins degradation during EGF and/or glutamine starvation of cultures, thereby demonstrating high potency in killing cancer cells by simultaneously modulating signaling and metabolic pathways. We propose a plausible mechanism of anti-cancer action by small degraders through the allosteric site of EGFR. Our data represent a rational and promising perspective in the treatment of aggressive tumors.

Effect of benzene intercalation on magnetization of Bi-oxides

Abstract: Intercalation by benzene had a dramatic effect on room-temperature DC magnetization curves of high- T c Bi-oxides. In contrast to weak paramagnetism ( χ ≈10 −6 emu/g per Gauss) of the initial samples, the intercalated samples exhibited an enhanced hysteretic magnetism with a complex field dependence. It is characterized by a steep rise at low fields, a broad maximum around 0.25 T, and a steady decline at higher fields up to 5.5 T, with magnetization becoming negative above 1.2 T. Hysteresis values were apparently field-independent within the studied range of 0 to 5.5 T. Tentative models are proposed to explain the observed anomalous magnetization.

Do gut symbiotes reflect the endemism of their host black flies (Diptera: Simuliidae) in the Caucasus of Armenia?

Abstract: Aim We tested the hypothesis that endemism of black flies in the Caucasus of Armenia is reflected in their gut symbiotes, ie trichomycete fungi and ichthyosporean protists Location The study area, Armenia, is a biodiversity hotspot, with high levels of plant and animal endemism Located in the southern Caucasus, Armenia is a rugged, mountainous, landlocked country of 29,800 km2, with fast-flowing rivers and little forested land About half of the 51 species of black flies in Armenia are endemic to the Caucasus Methods The larvae of 22 species of black flies, including seven endemic to the Caucasus, were collected from 35 sites throughout Armenia, from 1998 to 2004, and assayed microscopically for gut-inhabiting trichomycete fungi and ichthyosporean protists Results Nearly 68% of larval black flies in Armenia contained at least one species of gut symbiote, with a mean of 09 ± 004 species per host larva Eight species of trichomycete fungi and two species of ichthyosporeans were found in larval guts Seven of these species were recorded for the first time in Asian black flies Species accumulation curves showed no additional species of gut symbiotes after 17 host species and 22 sites had been examined All gut symbiotes were widely distributed, indicating an absence of endemic trichomycetes in the black flies of Armenia Main conclusions Although the Caucasus Region is noted for its high levels of endemism for plants and animals, including black flies, the gut symbiotes of black flies are all widespread species The absence of endemic gut symbiotes in larval black flies might be explained by their lack of host specificity; an absence of host specificity would not constrain the geographical distribution of the symbiotes

Non-metric dental analysis of a Bronze Age population from the Armenian Plateau

Abstract: The aim of this study is to assess the biological distance between populations from the Armenian highland, Georgia, Eastern Europe, Central Asia and Siberia on the basis of the frequency of non-metric dental traits. It is well known that these traits are characterized by high inter-population differentiation, low sexual dimorphism, and their recording is affected by relatively small intra and inter-observer error. These traits are successfully used in the description and explanation of ethno-genetic processes. Compara- tive analysis was performed on 30 populations, and the frequency of non-metric dental traits in all popula- tions was determined by principal component analysis. Based on our bio-distance results, we suggest there was a degree of genetic proximity among inland populations of the Armenian Plateau and Transcaucasian area at the beginning of the Bronze Age. The Armenian Plateau and Georgian samples and all those from Kalmykia (Pit Grave culture), the Ukraine (Tripolye culture), the Urals (Sintashtinskaya, Timber Grave cultures), the Volga region (Pit Grave, Balanovo, Fatianovo, Potapovsky cultures) and Central Asia (Go- nur-Depe) exhibited close affinities. This conclusion is consistent with that reported by other bio-distance studies examining non-metric cranial traits and Armenian Plateau samples.