Search results for "cyclic"

Improved synthesis and in vitro evaluation of the cytotoxic profile of oxysterols oxidized at C4 (4α- and 4β-hydroxycholesterol) and C7 (7-ketocholes…

2013

Whereas the biological activities of oxysterols oxidized at C7 (7-ketocholesterol (7KC), 7β-hydroxycholesterol (7β-OHC), 7α-hydroxycholesterol (7α-OHC)) are well documented, those of oxysterols oxidized at C4 (4β-hydroxycholesterol (4β-OHC), 4α-hydroxycholesterol (4α-OHC)) are not well known, especially on the cells of the central nervous system. Therefore, an improved methodology has been validated for 4β-OHC and 4α-OHC synthesis, and the effects on cell viability and cell growth of these molecules were studied on immortalized, tumoral and normal brain cells (158N, C6 and SK-N-BE cells, and mixed primary cultures of astrocytes and oligodendrocytes). Whereas inhibition of cell growth with 7…

Pharmacological Suppression of CNS Scarring by Deferoxamine Reduces Lesion Volume and Increases Regeneration in an In Vitro Model for Astroglial-Fibr…

2015

Lesion-induced scarring is a major impediment for regeneration of injured axons in the central nervous system (CNS). The collagen-rich glial-fibrous scar contains numerous axon growth inhibitory factors forming a regeneration-barrier for axons. We demonstrated previously that the combination of the iron chelator 2,2'-bipyridine-5,5'-decarboxylic acid (BPY-DCA) and 8-Br-cyclic AMP (cAMP) inhibits scar formation and collagen deposition, leading to enhanced axon regeneration and partial functional recovery after spinal cord injury. While BPY-DCA is not a clinical drug, the clinically approved iron chelator deferoxamine mesylate (DFO) may be a suitable alternative for anti-scarring treatment (A…

Neurosteroidogenesis in Rat Retinas

2002

Neurosteroids (steroids synthesized in the CNS) function by modulating neurotransmission. To establish an experimental model for investigation of neurosteroid synthesis and regulation, independent of blood-borne steroids, we examined the steroidogenic activity of isolated rat retinas. We identified progesterone, pregnenolone, dehydroepiandrosterone, desoxycorticosterone, 3 alpha,5 alpha-tetrahydrodesoxycorticosterone, 3 alpha-hydroxy-5 alpha-dihydroprogesterone, 17-hydroxyprogesterone, and 17-hydroxypregnenolone together with their esterified forms. As pregnenolone is the precursor of all steroids, its formation was studied in detail as an index of a steroid-synthesizing tissue. Pregnenolon…

Central Modulatory Neurons Control Fuel Selection in Flight Muscle of Migratory Locust

2003

Insect flight is one of the most intense and energy-demanding physiological activities. High carbohydrate oxidation rates are necessary for take-off, but, to spare the limited carbohydrate reserves, long-distance flyers, such as locusts, soon switch to lipid as the main fuel. We demonstrate that before a flight, locust muscles are metabolically poised for take-off by the release of octopamine from central modulatory dorsal unpaired median (DUM) neurons, which increases the levels of the potent glycolytic activator fructose 2,6-bisphosphate in flight muscle. Because DUM neurons innervating the flight muscles are active during rest but selectively inhibited during flight, they stimulate carbo…

Topological Decompositions of the Pauli Group and their Influence on Dynamical Systems

2021

In the present paper we show that it is possible to obtain the well known Pauli group $P=\langle X,Y,Z \ | \ X^2=Y^2=Z^2=1, (YZ)^4=(ZX)^4=(XY)^4=1 \rangle $ of order $16$ as an appropriate quotient group of two distinct spaces of orbits of the three dimensional sphere $S^3$. The first of these spaces of orbits is realized via an action of the quaternion group $Q_8$ on $S^3$; the second one via an action of the cyclic group of order four $\mathbb{Z}(4)$ on $S^3$. We deduce a result of decomposition of $P$ of topological nature and then we find, in connection with the theory of pseudo-fermions, a possible physical interpretation of this decomposition.

La symphonie des cercles circonscrits

2023

Scorpiand-like azamacrocycles prevent the chronic establishment of Trypanosoma cruzi in a murine model.

2013

Chagas disease is today one of the most important neglected diseases for its upcoming expansion to non-endemic areas and has become a threat to blood recipients in many countries. In this study, the trypanocidal activity of ten derivatives of a family of aza-scorpiand like macrocycles is evaluated against Trypanosoma cruzi in vitro and in vivo murine model in which the acute and chronic phases of Chagas disease were analyzed. The compounds 4, 3 and 1 were found to be more active against the parasite and less toxic against Vero cells than the reference drug benznidazole, 4 being the most active compound, particularly in the chronic phase. While all these compounds showed a remarkable degree …

S-Methylisothioharnstoffe, Bausteine kettenverzweigter Cimetidin-DerivateS-Methylisothioureas, Synthons for Chain-Branched Cimetidine Derivates

1987

A partir de S,S-dimethyl N-cyano dithiocarbonimidate et d'amino-2' alkyl (ramifie) thiomethyl-4 methyl-5 imidazoles (A), synthese des derives de A substitues sur l'amino-2' par [cyanoimino methylthiomethyle]

The reaction of aromatic α,β-unsaturated ketones with 4,5-diamino-1,6- dihydropyrimidin-6-ones

1994

The reaction of 4,5-diamino-1,6-dihydropyrimidin-6-ones 1 with one equivalent of the chalcones 2 leads in an acidic medium to the formation of the 2,4-diaryl-2,3,6,7-tetrahydro-1H-pyrimido[4,5-b][1,4]diazepin-6-ones 3a-m. The structure elucidation of the products is based on detailed nmr investigations including selective 13C[1H] decoupling experiments.

The Effect of Taper and Apical Diameter on the Cyclic Fatigue Resistance of Rotary Endodontic Files Using an Experimental Electronic Device

2021

The aim of this study was to analyze the effect of the taper and apical diameter of nickel&ndash