Effect of Time on Endothelium-Dependent Relaxations in Mice and Rat Thoracic Aortas

Temporal variations in the endothelium-dependent relaxant effects of acetylcholine (ACh) in mice and histamine (HA) in rat thoracic aorta have been studied. The relaxations induced by higher concentrations of ACh and HA were significantly dependent on the time the tissues were obtained. However, neither EC 50 (the concentration inducing half of the maximum response) values for ACh and HA, nor K B (antagonist dissociation constant) values for atropine and diphenhydramine were found to be statistically significant depending upon the time of obtaining aorta preparations. These results show that the in vitro responsiveness of mice and rat thoracic aortas to endothelium-dependent relaxant effects of ACh and HA, respectively, changes over a 24-h period. These variations might be dependent on a temporal rhythm in post-receptor events, i.e., guanylate cyclase-cGMP-phosphodiesterase system which mediates responses to endothelium-derived relaxing factor(s).     

Methylobacterium Species Promoting Rice and Barley Growth and Interaction Specificity Revealed with Whole-Cell Matrix-Assisted Laser Desorption / Ionization-Time-of-Flight Mass Spectrometry (MALDI-TOF/MS) Analysis

Methylobacterium species frequently inhabit plant surfaces and are able to utilize the methanol emitted from plants as carbon and energy sources. As some of the Methylobacterium species are known to promote plant growth, significant attention has been paid to the mechanism of growth promotion and the specificity of plant–microbe interactions. By screening our Methylobacterium isolate collection for the high growth promotion effect in vitro, we selected some candidates for field and pot growth tests for rice and barley, respectively. We found that inoculation resulted in better ripening of rice seeds, and increased the size of barley grains but not the total yield. In addition, using whole-cell matrix-assister laser desorption/ionization- time-of-flight mass spectrometry (MALDI-TOF/MS) analysis, we identified and classified Methylobacterium isolates from Methylobacterium-inoculated rice plants. The inoculated species could not be recovered from the rice plants, and in some cases, the Methylobacterium community structure was affected by the inoculation, but not with predomination of the inoculated species. The isolates from non-inoculated barley of various cultivars grown in the same field fell into just two species. These results suggest that there is a strong selection pressure at the species level of Methylobacterium residing on a given plant species, and that selection of appropriate species that can persist on the plant is important to achieve growth promotion.     

Biosafety, biodiversity and significance of Microbial Resource Centers (MRCs) in microbiology education

Summary Interest in the intrinsic behavior of microorganisms has led to the establishment of centers of expertise, known as Microbial Resource Centers (MRCs) built around specialized collections of cultures of microorganisms. Their main function is to accession, preserve and distribute authenticated, viable samples of microorganisms in consultation with the international scientific community for study and application. Microorganisms, which are exceptionally diverse, are found almost everywhere and affect human society in countless ways. Thus, modern microbiology has a great impact on medicine, agriculture, food science, ecology, genetics, biochemistry and many other fields. MRCs appear to be equally important to industry, to academia, and from the elementary to high school science teachers who can order specific educational strains. The basic microbiological knowledge of human society possesses the potential to revolutionize many aspects of human life. MRCs are a key resource to underpin these developments.     

Protective role of carnitine in breast cancer via decreasing arginase activity and increasing nitric oxide

Breast cancer remains one of the most common types of cancer. High levels of arginase and ornithine in different carcinomas may indicate their relation to cancer. Carnitine is a cofactor required for the transformation of free long-chain fatty acids into acetyl-carnitines. We have examined the protective effect of carnitine and the possibility that it disturbs arginase-nitric oxide (NO) interaction. Histopathological examination, arginase activity, ornithine and NO levels were determined in tumour tissues. Mitotic cells significantly decreased in the treatment group. Tissue arginase activity and ornithine levels decreased significantly with carnitine. NO levels were significantly higher in the treatment group. One of the possible mechanisms of carnitine's protective role in tumour progression might be its promotion of NO. This mechanism could decrease the production of tumour-promoting agents, polyamines, and increase the production of NO, thereby exerting a protective effect on cancer development.     

Daily Variations in the Responses to Papaverine but not Theophylline in Rat Aorta

The presence of temporal patterns in the responses of vascular smooth muscle to relaxing agents have been known. The aim of this study was to examine the variations in the in vitro sensitivity of rat aorta to papaverine and theophylline in both endothelium-intact and -denuded rings. The animals were synchronized with a 12-h light: 12-h dark schedule. Rat thoracic aorta rings were obtained from animals sacrificed at six different times (09:00, 13:00, 17:00, 21:00, 01:00 and 05:00) of the day. Tissues were precontracted submaximally with phenylephrine and then were relaxed by papaverine (10^?8 ? 10^?4 M) and theophylline (10^?7 ? 10^?3 M) applied cumulatively. The responses to most of the concentrations and EC₅₀ values for papaverine demonstrated an ultradian rhythm with an 8 h periodicity. Time-dependent variations were not found in the responses to theophylline. The results are discussed in relation with the time-dependent differences in signal transducing mechanisms.     

Molecular structure and effects of intermolecular hydrogen bonding on the vibrational spectrum of trifluorothymine, an antitumor and antiviral agent

In the present work, the experimental and the theoretical vibrational spectra of trifluorothymine were investigated. The FT-IR (400-4000?cm(-1)) and μ-Raman spectra (100-4000?cm(-1)) of trifluorothymine in the solid phase were recorded. The geometric parameters (bond lengths and bond angles) and vibrational frequencies of the title molecule in the ground state were calculated using ab initio Hartree-Fock (HF) method and density functional theory (B3LYP) method with the 6-31++G(d,p) and 6-311++G(d,p) basis sets for the first time. The optimized geometric parameters and the theoretical vibrational frequencies were found to be in good agreement with the corresponding experimental data and with results found in the literature. Vibrational frequencies were assigned based on the potential energy distribution using the VEDA 4 program. The dimeric form of trifluorothymine was also simulated to evaluate the effect of intermolecular hydrogen bonding on the vibrational frequencies. It was observed that the stretching modes shifted to lower frequencies, while the in-plane and out-of-plane bending modes shifted to higher frequencies due to the intermolecular N-H?O hydrogen bonds.     

Composition and antimicrobial activity of essential oils from Centaurea sessilis and Centaurea armena

The essential oils of air-dried Centaurea sessilis and Centaurea armena obtained by hydrodistillation were analyzed by gas chromatography-mass spectrometry (GC-MS). Forty and twenty components were identified in the essential oils and the main component of these taxons was beta-eudesmol in the ratios of 12.4% and 19.3% from C. sessilis and C. armena, respectively. The antimicrobial activity of the isolated essential oil of the plants was also investigated. They showed moderate antibacterial activity against Gram-positive and Gram-negative bacteria, but no antifungal activity was observed against two yeastlike fungi.     

Photodimerizations of hydroxy- and benzoylated 4-azachalcones and quantum chemical investigation of the reactions

Photodimerization reactions of compounds 4–6 gave four new cyclobutane-containing compounds (7–9) with full control over the stereochemistry at the four stereogenic centers. These new cyclobutane-containing compounds had β-truxinic (7a), δ-truxinic (7b and 9), and ε-truxillic (8) structures. However, o-, m-, and p-hydroxy 4-azachalcones (1–3) did not give photochemical cyclization products under any conditions (in solvent or in their solid or molten states). Experimental data suggested the possibility of frontier orbital control over stereochemical behavior, so some theoretical calculations were performed. Full geometrical optimization of compounds 1–9 was performed via DFT B3LYP/6-31⁺G**, and their electronic structures were also investigated. The geometries of the singlet and triplet states were initially optimized by density functional theory (DFT) and the configuration interaction singles (CIS) B3LYP/3-21⁺G** level. An additional calculation was performed for the triplet state using the ground-state geometry. The possible photochemical dimerization products of compounds 7–9 (a–g) and the intrinsic reaction coordinates (IRCs) of the reactions of compounds 4–6 were calculated theoretically by the DFT/3-21⁺G** method. The configurations (reactant, transition state, product, and reaction pathway) corresponding to the stationary points (minima or saddle points) were determined. The intrinsic reaction coordinates were followed to verify the energy profiles that connect each TS to the appropriate local minimum. The dimeric products expected from the calculations coincided with the dimers produced experimentally.     

Synthesis of novel imidazopyridines and their biological evaluation as potent anticancer agents: A promising candidate for glioblastoma

Novel imidazopyridine derivatives were synthesized according to a very simple protocol and then subjected to cytotoxicity testing against LN-405 cells. Two of the compounds exhibited antiproliferative effects on LN-405 cells at 10 and 75?µM and were selected as lead compounds for further study. Safety experiment for lead compounds on WS1 was carried out and IC₅₀ values were calculated as 480 and 844?µM. LN-405 cell line were incubated with the lead compounds and then tested for DNA damage by comet assay and effects on cell cycle using flow cytometry. The results of these two tests showed that both lead compounds affected the G0/G1 phase and did not allow the cells to reach the synthesis phase. The log BB (blood–brain barrier) and Caco-2 permeability of the synthesized molecules were calculated and it was shown that imidazopyridine derivatives taken orally are likely to pass through gastrointestinal membrane and the blood–brain barrier.