Search results for "Sulfoxide"

Functional, biochemical and morphological studies on human bronchi after cryopreservation

1995

1. Human isolated bronchi have been investigated as fresh tissue or after storage (7 and 30 days) at -196 degrees C in foetal calf serum containing 1.8 M dimethyl sulphoxide. 2. After cryopreservation, the maximal contractile response to acetylcholine (3 mM) was reduced (approximately 25%) but the difference did not reach significance statistically. Maximal responses to other spasmogens tested (histamine, [Nle10]NKA(4-10), bradykinin, leukotriene D4, U46619, and KCl) did not differ between unfrozen and frozen/thawed tissues. The sensitivity of cryopreserved tissues to the constrictor agents tested was similar to that of fresh tissues. 3. The accumulation of inositol phosphates produced by a…

Long-term storage in liquid nitrogen does not affect cell viability in cardiac valve allografts

2007

Liquid nitrogen is the most common medium used by tissue banks for the storage of cryopreserved heart valves. This study evaluates the effect of the length of storage on human cryopreserved heart valves. Human tissues (14 aortic and 13 pulmonary) were frozen in a controlled-rate freezer (1 degrees C/min) and stored in the liquid phase of a nitrogen tank for 9.1+/-1.6 years. The preservative solution was medium M199 containing 5% human serum albumin and 10% Me(2)SO. After thawing in a water bath at 42 degrees C, the cryoprotectant was removed. Then, fragments from vascular wall and leaflet were dissected. Explant cultures and histological studies were performed in order to assess cell viabil…

Anti-Inflammatory Effects of Onions: Inhibition of Chemotaxis of Human Polymorphonuclear Leukocytes by Thiosulfinates and Cepaenes

1990

Seven different synthetic thiosulfinates, and cepaene- and/or thiosulfinate-rich onion extracts were found to inhibit in vitro the chemotaxis of human granulocytes induced by formyl-methionine-leucinephenylalanine in a dose-dependent manner and at a concentration range of 0.1–100 μ<i>M</i>. Diphenylthiosulfinate showed the highest activity and was found to be more active than prednisolone. The anti-inflammatory properties of onion extracts are related, at least in part, to the inhibition of inflammatory cell influx by thiosulfinates and cepaenes.

Requirement for the Proton-Pumping NADH Dehydrogenase I of Escherichia Coli in Respiration of NADH to Fumarate and Its Bioenergetic Implications

1997

In Escherichia coli the expression of the nuo genes encoding the proton pumping NADH dehydrogenase I is stimulated by the presence of fumarate during anaerobic respiration. The regulatory sites required for the induction by fumarate, nitrate and O2 are located at positions around –309, –277, and downstream of –231 bp, respectively, relative to the transcriptional-start site. The fumarate regulator has to be different from the O2 and nitrate regulators ArcA and NarL. For growth by fumarate respiration, the presence of NADH dehydrogenase I was essential, in contrast to aerobic or nitrate respiration which used preferentially NADH dehydrogenase II. The electron transport from NADH to fumarate …

ESR and electrochemical studies of 2-acylpyridines and 6,6'-diacyl-2,2'-bipyridines.

2005

Abstract The ESR spectra of radicals obtained by electrolytic reduction of 2-acylpyridines and 6,6′-diacyl-2,2′-bipyridines were measured in dimethylsulfoxide (DMSO) and analyzed by quantum chemical calculations. The electrochemistry of these compounds was characterized using cyclic voltammetry, in DMSO solvent. The results showed a two step reduction mechanism, first wave was assigned to the generation of the correspondent free radical species, and the second wave was assigned to the dianion derivatives. AM1 and DFT calculations were performed to obtain the optimized geometries, theoretical hyperfine constants, and spin distributions, respectively. The theoretical results are in complete a…

Melatonin protects human red blood cells from oxidative hemolysis: new insights into the radical-scavenging activity.

1999

Antioxidant activity of melatonin in human erythrocytes, exposed to oxidative stress by cumene hydroperoxide (cumOOH), was investigated. CumOOH at 300 microM progressively oxidized a 1% suspension of red blood cells (RBCs), leading to 100% hemolysis in 180 min. Malondialdehyde and protein carbonyls in the membrane showed a progressive increase, as a result of the oxidative damage to membrane lipids and proteins, reaching peak values after 30 and 40 min, respectively. The membrane antioxidant vitamin E and the cytosolic reduced glutathione (GSH) were totally depleted in 20 min. As a consequence of the irreversible oxidative damage to hemoglobin (Hb), hemin accumulated into the RBC membrane d…

Synthesis, chemical characterization and preliminary in vitro antitumor activity evaluation of new ruthenium(II) complexes with sugar derivatives

2011

Abstract Three new complexes of Ru(II), namely [RuCl 2 (Glun-N,O) 2 ]Na 2 ( I ; Glun = glucosaminate), [RuCl 2 (1-Tglu)(EtOH) 2 ]Na ( II ; 1-Tglu = 1-thio-β- d -glucose) and [Ru 2 (EtOH) 6 (AL)Cl 4 ] ( III ; AL = 6′-aminolactose) were prepared from the same Ru(II) precursor, [RuCl 2 (DMSO) 4 ] (DMSO = dimethyl sulfoxide). The characterization of the complexes was carried out by elemental analysis, FT-IR, ES-MS, NMR, EXAFS and DFT calculations. The effectiveness of the complexes on metastatic melanoma A 375 was investigated. The results show that complex II is the most active species.

1986

The kinetics of polyamidation was investigated for the reaction of diphenyl terephthalate as activated diester with trimethylhexamethylenediamine (1 : 1 mixture of 2,2,4- and 2,4,4-trimethyl isomers) in dimethyl sulfoxide. The good solubility of the resulting polyamide (Trogamid®(poly(iminoterephthaloylimino-x,y,z-trimethylhexamethylene))) assured a reaction in which all reactants, especially the polyamide, were soluble. The conversion was followed by analysis of the phenol set free and by measuring the number-average degree of polymerization Pn of the polyamide. The reaction obeyed an overall second order with the principle of equal reactivity of functional groups fulfilled for Pn ≿ 16. De…

1986

The aminolysis of diphenyl terephthalate by means of hexylamine was studied in dimethyl sulfoxide as a model reaction for polyamidation. The kinetic analysis showed that the two ester groups of the diphenyl ester do not react independently. Furthermore, the reaction of the first ester group was of mixed second and third order, while the reaction of the second ester group contained only a second order term. The rate constants found were used to determine the Arrhenius activation parameters.

ChemInform Abstract: Efficient Synthesis of Racemic and Chiral Alkenyl Sulfoxides by Palladium-Catalyzed Suzuki Coupling.

2010

Alkenyl sulfoxide derivatives are obtained in high yields through a palladium-catalyzed Suzuki/Miyaura cross-coupling reaction of racemic and chiral 1-halo sulfoxides with aryl and alkenyl boronic acids. Chiral substrates react with no loss of optical purity and high optical yields. The reaction takes place with different palladium catalysts, such as Pd(PPh 3 ) 4 or Pd(OAc) 2 /DABCO. Although nitrogen ligands like DABCO lead to an active palladium catalyst, they are less effective than the phosphine ones.