Presence Of Dimethyl Sulphoxide Research Articles

Inositol lipids and phosphates in the regulation of the growth and differentiation of haemopoietic and other cells

Stimulation of phosphatidylinositol 4,5-bisphosphate hydrolysis is an important signalling reaction involved in the responses of cells to some, but not all, stimuli that promote cell proliferation. Active agents in this regard include antigens activating T and B lymphocytes, angiotensin (employing a receptor encoded by the mas oncogene), bombesin and platelet-derived growth factor PDGF). However, accumulating evidence suggests that inositol lipids and phosphates also have other roles in the regulation of cell growth and differentiation. Growth factor receptors that encode tyrosine kinases (such as that for PDGF) activate a kinase that synthesises phosphatidylinositol 3-phosphate, a novel lipid, and loss of this kinase-activating function abolishes growth-promoting activity. Human interleukin-4, a lymphokine that activates B lymphocytes, appears to employ phosphatidylinositol 4,5-bisphosphate hydrolysis as a brief initial signal that is followed by a sustained rise in cyclic adenosine monophosphate (cAMP): both signals are needed for the successful induction of the surface antigen CD23. Moreover, the same inositol lipid signalling pathway as is employed by antigen-stimulated mature T lymphocytes to provoke proliferation may be redeployed in immature T cells to trigger their elimination when they encounter self-antigens. Finally, studies of HL60 promyelocytic cells have shown that these cells contain high concentrations of inositol 3,4,5,6-tetrakisphosphate, 1,3,4,5,6-pentakisphosphate and hexakisphosphate, three inositol polyphosphates that are probably formed independently of inositol lipid metabolism. When these cells are induced to differentiate either towards neutrophils (in the presence of dimethylsulphoxide) or macrophages (in phorbol myristate acetate), cessation of growth and acquisition of differentiated characteristics are accompanied by large and different changes in the concentrations of these inositol phosphates that may be characteristic of these two pathways of differentiation.

In vitro plant regeneration and ethylmethanesulphonate (EMS) uptake in somatic embryos of date palm (Phoenix dactylifera L.)

The effect of the auxins dicamba (3,6-dichloro-2-methoxybenzoic acid) and picloram (4-amino-3,5,6-trichloropicolinic acid) on callus growth and embryogenesis in Phoenix dactylifera L. was investigated. Maximum callus fresh weight was obtained in nutrient medium enriched with 200 µm picloram. Somatic embryogenesis and subsequent plant regeneration was achieved following transfer of such calli to hormone-free medium. Germination of the somatic embryos was influenced by treatment with the chemical mutagen ethylmethanesulphonate (EMS). Uptake of the labelled mutagen ([14C]EMS) by the somatic embryos increased with increased incubation time. Presence of dimethyl sulphoxide (DMSO) as a carrier agent during mutagenic treatment was necessary for efficient mutagen uptake.

In vitro action of ethylmethanesulphonate on banana shoot tips

Shoot tips excised from two banana ( Musa acuminata) clones (SH-3362, a diploid AA, and cultivar ‘Grand Nain’ mutant (GN-60Gy/A), a triploid AAA) were treated with various concentrations of the mutagen ethylmethanesulphonate (EMS). The number of newly initiated adventitious buds decreased with increased concentrations of EMS. Presence of dimethylsulphoxide (DMSO) in combination with EMS affected the growth and development of the shoot tips. Uptake of the labelled mutagen ( 14C EMS) was greatly influenced by time of incubation and presence of DMSO as a carrier agent. Microautoradiography of histological sections of shoot tips confirmed the accumulation of the labelled mutagen in the shoot apical meristem, leaf primordia and more extensively in the corm, from which new adventitious buds are initiated.

Modification of poly(N‐vinylcarbazole): Nitration and thermally stimulated depolarization current study

AbstractIn order to introduce some electronic affinity in poly(N‐vinylcarbazole), we proceeded to incorporate NO2 groups in its pendant aromatic group. Two samples obtained by different polymerization processes were chosen: a commercial sample LUVICAN (BASF) and a cationically polymerized one. Both samples were fractionated and characterized by GPC and viscometry. The first ones were treated with a sulphuric acid‐nitric acid mixture, while the second ones were nitrated in presence of dimethyl sulphoxide. The glass transition temperature and the corresponding dielectric α relaxation were studied by differential scanning calorimetry and thermally stimulated currents techniques, respectively. Rigidity of the macromolecular chain and the degree of nitration lead to different behaviour in the relaxation process.

Chromosome analysis of two-cell mouse embryos frozen by slow and ultrarapid methods using two different cryoprotectants

Three freezing methods (slow-1,2 propanediol; ultrarapid-dimethyl sulphoxide; ultrarapid-1,2 propanediol) were used to assess the effects of low temperature storage on morphologic features and chromosome make-up of 2-cell mouse embryos. Weekly batches (15 weeks) of 2-cell mouse embryos were frozen for a period of 7 days using these three freezing methods, then thawed and subjected to chromosome analysis. After thawing, all three freezing regimens yielded 70.2% to 75.8% of healthy intact 2-cell embryos, and 5.5% to 8.1% of embryos with one healthy blastomere intact, respectively, out of 817 embryos examined. Chromosome analysis was possible in all 1- and 2-cell embryos. The incidence of aneuploidy and polyploidy in frozen-thawed embryos of all three methods (2.8% to 3.4%; 4.0% to 6.5%) was not significantly different from that of control unfrozen embryos (3.0%; 6.0%) (P greater than 0.01). Mitotic crossing over was observed in 3.5% of embryos frozen-thawed by the ultrarapid-dimethyl sulphoxide method only. It is not clear how the mitotic crossing over was induced by ultrarapid freezing in the presence of dimethyl sulphoxide.

Relaxed specificity of the EcoRV restriction endonuclease

The EcoRV restriction endonuclease normally shows a high specificity for its recognition site on DNA, GATATC. In standard reactions, it cleaves DNA at this site several orders of magnitude more readily than at any alternative sequence. But in the presence of dimethyl sulphoxide and at high pH, the EcoRV enzyme cleaves DNA at several sites that differ from its recognition site by one nucleotide. Of the 18 (3 X 6) possible sequences that differ from GATATC by one base, all were cleaved readily except for the following 4 sites: T ATATC, C ATATC, GATAT A and GATAT G . However, two of the sites that could be cleaved by EcoRV in the presence of dimethyl sulphoxide, GA G ATC and GAT C TC, were only cleaved on DNA that lacked dam methylation: both contain the sequence GATC, the recognition site for the dam methylase of Escherichia coli.

Applications of kinetic methods in non-aqueous catalytic thermometric titrimetry. Part I. Evaluation of acetylation, α-methylstyrene and acrylonitrile indicator systems

Kinetic methods, based on the measurement of the rates of reaction of reagent systems originally developed as thermometric indicators, may be used as a method to determine perchloric acid, potassium hydroxide and quinoline in microgram amounts. The reaction rate is measured by the initial slope of the temperature-time graph recorded when the sample compound is added to the reagent mixture. Perchloric acid is determined using both acetylation and α-methylstyrene indicator systems, and potassium hydroxide is determined with the acrylonitrile reagent. Quinoline is determined on mixtures of quinoline and an excess of perchloric acid using the acetylation indicator reaction. The rate of the acrylonitrile reaction is influenced significantly by the presence of dimethyl sulphoxide, which is used to increase the sensitivity of the method. In the α-methylstyrene reaction, the induction time before the reaction commences is also used to measure the catalyst concentration.

Quantitative determination, isolation and characterization of pig lung tubulin.

Tubulin from pig lung was quantitatively determined, isolated and characterized. It accounted for about 0.3-0.4% of the total soluble protein of pig lung, as measured by colchicine binding or radioimmunoassay. Purified tubulin was obtained by several cycles of polymerization and depolymerization in the presence of dimethyl sulphoxide and 2H2O as stabilizing agents. The proteolytic cleavage patterns of the lung tubulin subunits closely resembled those of other mammalian cytoplasmic tubulin subunits, such as those of brain and kidney. However, the pattern of lung isotubulins on isoelectric focusing differed substantially from that of brain isotubulins . These differences did not appear to be the result of major lung tubulin post-translational modifications, since approximately the same pattern of isotubulins was found for the tubulin synthesized by lung poly(A)-containing mRNA in a reticulocyte system in vitro.

Electron flow to dimethylsulphoxide or trimethylamine-N-oxide generates a membrane potential in Rhodopseudomonas capsulata.

Under dark and essentially anaerobic conditions electron flow to either dimethylsulphoxide or trimethylamine-N-oxide in cells of Rhodopseudomonas capsulata has been shown to generate a membrane potential. This conclusion is based on the observation of a red shift in the carotenoid absorption band which is a well characterised indicator of membrane potential in this bacterium. The magnitude of the dimethylsulphoxide- or trimethylamine-N-oxide-dependent membrane potential was reduced either by a protonophore uncoupler of oxidative phosphorylation or synergistically by a combination of a protonophore plus rotenone, an inhibitor of electron flow from NADH dehydrogenase. These findings, together with the observation that venturicidin, an inhibitor of the proton translocating ATPase, did not reduce the membrane potential, show that electron flow to dimethylsulphoxide or trimethylamine-N-oxide is coupled to proton translocation. Thus contrary to some previous proposals dark and anaerobic growth of Rps. capsulata in the presence of dimethylsulphoxide or trimethylamine-N-oxide cannot be regarded as purely fermentative.

Changes in the cytochrome composition of Rhodopseudomonas sphaeroides grown aerobically, photosynthetically and on dimethyl sulphoxide.

Several strains and mutants of Rhodopseudomonas sphaeroides can be grown anaerobically in the dark in the presence of dimethyl sulphoxide as an electron acceptor. During adaptation to this fermentative mode of growth, two major c-type cytochromes are synthesized, one with Mr 45 000 and the second with Mr 20 000 and a midpoint potential of +120 mV. These cytochromes are barely detectable in membranes prepared from cells grown in aerobic or photosynthetic conditions. An electrophoretic method is presented for the detection of the b-type and c-type cytochromes of pigmented or unpigmented membranes. The method resolves three b-type cytochromes and four c-type cytochromes in membranes from aerobically and photosynthetically grown cells.

Differential staining of polyanions according to critical electrolyte concentration principles in mixed solvents

SUMMARYThree types of cationic reagent—cellulosic anion exchangers, cationic phthalocyanin dyes and detergents—formed insoluble complexes with the polyanions heparin, chondroitin‐4‐sulphate, hyaluronate, alginate and DNA. Dissociation of their complexes by MgCl2 was a critical phenomenon, occurring at a sharply defined concentration, the critical electrolyte concentration (CEC), in water and in water‐organic‐solvent mixtures. CECs of polysulphates were always higher than those of polycarboxylates or polyphosphates, especially in the presence of dimethyl sulphoxide or ethanol. The latter effect should improve biochemical fractionations and differential histochemical staining of polyanions.A general theoretical framework is proposed. Complex formation is promoted by electrostatic attractions, and results in a loss of polymer mixing energy. Electrolytes suppress the electrostatic interaction, thus preventing complex formation. More efficient suppression of the electrostatic interaction is required in a ‘worsening’ solvent, i.e. where a rise in CEC occurs. Plots of CEC against solvent composition are interpreted on these bases. Available data on electrolyte solutions account for specific ionic effects.The dissociation of phthalocyanin dye micelles in aqueous dimethyl sulphoxide, etc, was studied spectroscopically. The results support and extend the conclusions derived from the insoluble anion‐exchange celluloses.The general concepts serve as a bridge between biochemical and histochemical fractionations (i.e. specific staining of substrates).

Control of muscle and neuronal differentiation in a cultured embryonal carcinoma cell line.

Pluripotent murine embryonal carcinoma cells can differentiate in culture into many tissue types similar to those normally found in early embryos and may be useful in investigating some developmental events. Central to our understanding of embryonic development are explanations of cellular determination, that is, the commitment of early embryonic cells to form divergent cell types. Of relevance is recent work with the F9 line of embryonal carcinoma cells which suggests that certain extra-embryonic cell types are specifically formed following treatment of undifferentiated cells with drugs and the manipulation of culture conditions. We report here that the P19 line of embryonic carcinoma cells may provide and analogous system in which drugs can be used to manipulate the formation of tissues which normally comprise the fetus. In the presence of dimethyl sulphoxide (DMSO) aggregates of P19 cells differentiate rapidly to form large amounts of cardiac and skeletal muscle but no neurones or glia. We have previously shown that in the presence of high concentrations of retinoic acid (greater than 5 x 10(-7) M), aggregates of these same cells develop into neuronal and glial tissues but not muscle. Thus, drugs can be used to generate two quite different spectra of embryonic tissue types from the same population of embryonal carcinoma cells.

Interactions of glycerol monooleate and dimethylsulphoxide with phospholipids A differential scanning calorimetry and 31P-NMR study

1. A comparative study has been made of the effects of the fusogens glycerol monooleate and dimethylsulphoxide on the polymorphic phase behaviour of dipalmitoyl phosphatidylcholine and dipalmitoyl phosphatidylethanolamine by differential scanning calorimetry and 31P-NMR techniques. 2. Glycerol monooleate induces a reduction in the temperature, cooperativity and enthalpy of the gel to liquid-crystal transitions of dipalmitoyl phosphatidylcholine and dipalmitoyl phosphatidylethanolamine, whereas dimethylsulphoxide induces an increase in the temperature and enthalpy and a reduction in the cooperativity of the gel to liquid-crystal transitions for those same phospholipids. 3. Glycerol monooleate induces the formation of isotropic and hexagonal (H II) phases when mixed with either dipalmitoyl phosphatidylcholine or dipalmitoyl phosphatidylethanolamine. By contrast, in the presence of dimethylsulphoxide, those same phospholipids retain the lamellar configuration observed in the absence of fusogen. 4. These results are discussed in terms of the mechanisms of chemically induced cell fusion.

Charge transfer spectra, kinetics and thermodynamics for thiourea, thioacetamide and dithiooxamide complexes of pentacyanoferrate(II)

Abstract The importance of π-backbonding in the pentacyanoferrate(II) complexes of thioamides has been demonstrated by a systematic study on the electronic spectra, kinetics and equilibrium, and on the electrochemistry of the thiourea (tu), thioacetamide (ta) and dithiooxamide (dto) derivatives. The complexes exhibit a characteristic absorption band at 305 nm (tu), 367 nm (ta) and 550 nm (dto), which was assigned to a metal-to-ligand charge transfer transition involving the thioamide group. The kinetics of formation of the complexes starting from the aquopentacyanoferrate(II) ion, and of substitution reactions in the presence of dimethyl sulphoxide or isonicotinamide, were consistent with a dissociative mechanism. From cyclic voltammetry, the Eθ values were evaluated as 300 mV (tu), 405 mV (ta) and 520 mV (dto), while the pKa of the coordinated cyanides in the complexes were respectively, 2.56, 2.38 and 2.13. The trends in the thermodynamic parameters of the iron(II) complexes followed the acceptor properties of the ligands; however, they were reversed in the oxidized state, where the major role is played by σ and π-donor interactions.

ChemInform Abstract: DIRECT ELECTROCHEMICAL SYNTHESIS OF CATIONIC COMPLEXES

AbstractDie elektrochemische Oxidation von Übergangsmetallen oder Metallen der Hauptgruppe in Gegenwart von DMSO oder MeCN und HBF4 liefert mit 80‐90% Ausb. die Kationen (I) als Tetra‐ fluoroborate.

Direct electrochemical synthesis of cationic complexes

The electrochemical oxidation of both transition and main-group metals in the presence of dimethyl sulphoxide (dmso) or acetonitrile plus tetrafluoroboric acid gives rise to salts of the type [ML6][BF4]n[M = V, Cr, Mn, Fe, Co, Ni, Zn, Cd, or In; L = dmso or CH3CN (not all combinations); n= 2 or 3, depending on M]. The electrochemical conditions described give gram quantities of product from 5–25 h electrolyses with simple apparatus.

Studies in azide chemistry. Part IX [1]. Investigations involving fluorinated azidopyrimidines and 4-azido-3-chloro-2,5,6-trifluoropyridine

4-Azido-2,5,6-trifluoro- and 4,6-diazido-2,5-difluoro- pyrimidine were obtained by treating tetrafluoropyrimidine with sodium azide in acetonitrile; similar azidation of 5-chlorotrifluoropyrimidine gave 4-azido-5-chloro-2,6-difluoro- and 4,6-diazido-5-chloro-2-fluoro-pyrimidine. Each monoazide reacted with triphenylphosphine to yield the corresponding iminophosphorane (Staudinger reaction), and the trifluoro- compound gave cycloadducts when heated with phenylacetylene [→ 4-phenyl-1-(2,5,6-trifluoro-4-pyrimidinyl)-1,2,3- triazole] and acrylonitrile [→ 2-cyano-1-(2,5,6-trifluoro- 4-pyrimidinyl)aziridine]; attack on the trifluoro-azide by the sodium salt of pentafluoroaniline produced 4-azido-2,5- difluoro-6-(pentafluorophenylamino)pyrimidine and bis(4- azido-2,5-difluoro-6-pyrimidinyl)(pentafluorophenyl)amine. Attempts to intercept nitrenes during thermal decomposition of both mono-azides failed. Thermolysis of 4-azido-3-chloro- 2,5,6-trifluoropyridine in the presence of dimethyl sulphoxide, cyclohexane, or pentafluoroaniline gave products [py FNS(O)Me 2, py FNHC 6H 11, and py FNNPh F (PY F = 3-chlorotrifluoro-4-pyridyl), respectively] compatible with release of the corresponding nitrene.

The influence of various chemical additives on the survival of vesicular exanthema virus in aerosols.

The influence of relative humidity (r.h.) on the survival of vesicular exanthema virus (VEV) in aerosols at I s and during the next 5 min when generated from phosphate buffer solution containing polyhydroxy compounds, dimethyl sulphoxide, salt or protein has been examined. VEV was sensitive to r.h. in the range of 40 to 60% in the presence of bovine serum albumin, glucose, inositol or phosphate buffer. Addition of sodium chloride stabilized the virus in aerosols at mid-range r.h. both immediately after generation and after a period of storage for 5 min. In the presence of dimethyl sulphoxide or glycerol, virus survival was reduced at 20% r.h. at I s and at all r.h. during the first 5 min. Pre-humidification did not produce any significant difference in virus recovery.

Properties of the hydrogenase of Megasphaera elsdenii.

The catalytic activities of Megasphaera elsdenii hydrogenase are stimulated by salts. The stimulation is due to the anion: the more chaotropic the anion, the greater the effect. Dithionite-reduced and dye-oxidised preparations of hydrogenase are inactivated by reaction with oxygen. The inactivation of the reduced enzyme by excess oxygen follows pseudo-first-order kinetics; the reaction order for the oxidised enzyme has not been established. The rate of oxygen-inactivation is decreased by bovine serum albumin. The hydrogen production activity decreases in the presence of dimethylsulphoxide and ethylene glycol. The hydrogen oxidation activity is stimulated by dimethylsulphoxide, and the activity remains linear with time at concentrations up to 50% (v/v). Above 70% dimethylsulphoxide the steady-state activity of hydrogenase is abolished for both types of activity. The enzyme is more stable in a hydrogen atmosphere than in an argon atmosphere, and the oxidized enzyme is more stable than the reduced enzyme. The enzyme is isolated in the presence of dithionite and it is therefore reduced. When the enzyme is oxidized by treatment with 2,6-dichloroindophenol or with (bi)sulphite, its activity increases by up to 65%; this activation is not reversed when the enzyme is re-reduced. The increase in activity is associated with a change of the redox potential of the incubation medium to a less negative value; half of the maximum activation occurs at -0.41 V. The electron paramagnetic resonance spectrum of the dithionite-reduced hydrogenase resembles that of a reduced ferredoxin-type of spectrum with two 4Fe-4S clusters. The spectrum of the oxidized enzyme is similar to that of Chromatium high-potential iron-sulphur protein. No redox potentials can be ascribed to these spectra since the redox system changes upon freezing to liquid helium temperatures.

Control of transcription of the globin gene.

This report provides a more rigorous proof of previous findings that the RNA transcribed in vitro from the chromatins of different organs shows different sequence specificities. Here the particular case of the globin gene is considered for a comparison of embryonic mouse liver chromatin and mouse brain chromatin using the reverse transcriptase cDNA copy of globin 9S m RNA as a definitive probe. It can be shown that globin sequences are transcribed in vitro from embryonic liver chromatin and not brain chromatin. This specificity in liver chromatin can be reconstituted after dissociation of the structural elements of the chromatin. It can be shown that the non-histone protein fraction of liver chromatin can confer specificity for the transcription of globin sequences from brain chromatin which otherwise lacks this ability. Preliminary results are described with the Friend cell system, in which haemoglobin synthesis can be induced in vitro in the presence of dimethylsulphoxide.