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PubMedDate not supplied

Red blood cell indices, cation content, and membrane cation transports.

In sickle cell disease, in the homozygous state, the increased heterogeneity of erythrocytes results mainly from membrane defects secondary to Hb S polymerization and the increased survival of F cells. The density distribution curve, using phthalate esters or the red blood cell indices measured with the H*3 system, are useful methods for the hematological follow-up of patients under specific therapies. The methods evaluating the red blood cell cation contents and the abnormal membrane potassium transport pathways are also described, in order to evaluate agents which can restore normal hemoglobin concentration and water content in dehydrated sickle cells.

Anemia, Sickle Cell↗
PubMed1991

[The relationship between the cation and protein content, cationic transport and the rate of protein synthesis detected in cells in the presence and in the absence of ouabain].

The measurements were made of monovalent cation (K+ + Rb+, Na+) and protein contents, of leucin incorporation into the protein (protein synthesis), and of ouabain-sensitive K+ influx during the growth of the Jurkat culture cells in the presence or in the absence of ouabain. All the data were calculated per cell. The time dependences of these parameters are nonlinear [correction of unline] curves. The results of three independent measurements are not reproduced. The problem was to find out an intracellular "main" parameter, so that the dependences between this and the rest of parameters be of line character. It has been found that it is the protein synthesis rate that may be taken as the main parameter, because between the protein synthesis rate and all the other parameters there is the line connection. Comparative results obtained with or without ouabain showed that K+ and Na+ concentrations in the cell were different, although the constants of the rate of protein synthesis were the same. This points to the same type of change of the protein synthesis process in the cells growing with or without ouabain.

Biological Transport↗
PubMed1988

Divalent cation involvement in the action of Clostridium perfringens type A enterotoxin. Early events in enterotoxin action are divalent cation-independent.

Clostridium perfringens type A enterotoxin (CPE) is a membrane-active cytotoxin. There are a number of recognized early steps in CPE cytotoxicity including binding of CPE to a protein receptor, insertion of CPE into membranes, and CPE-mediated induction of changes in membrane permeability for small molecules such as ions and amino acids. Further support for the existence of these early steps and further characterization of these events are presented in this report. We now report that these early steps in CPE action are largely independent of extracellular divalent cations. It is also shown that 3H-nucleotide release, known to be a later CPE effect, is Ca2+-dependent. A model for CPE cytotoxicity is suggested involving CPE action as a two-step process with Ca2+-independent early steps and Ca2+-dependent late steps.

Aminoisobutyric Acids↗
PubMed1976

The role of divalent cations in activation of the sea urchin egg. I. Effect of fertilization on divalent cation content.

The Ca and Mg content of unfertilized sea urchin eggs (3 and 21 mumole/ml eggs) remains remarkably constant over periods of hours, even when the eggs are suspended in Ca- or Mg-free sea water. After fertilization the Ca content of eggs in regular sea water increases sharply by about 20%, followed by a decrease to the unfertilized level by 40 minutes. However, if the fertilized eggs are washed three minutes in Ca-free sea water a sharp decrease in the Ca content occurs amounting to 30% of the total in the first 40 minutes, with little change thereafter. Suspension of the eggs in Ca-free sea water results in an even greater loss of Ca amounting to about 43% of the total in the same time interval, followed by a continuing slow loss. It is concluded that fertilization initiates the intracellular release of Ca, which is then extruded. For unwashed eggs this change is masked by the simultaneous generation of new extra-cellular coats with high affinity for Ca. Changes in the Mg content of fertilized eggs follow the same general pattern except that absorption of this divalent cation to the extracellular coats is minimal.

Animals↗
PubMed1980

Effects of divalent cations on amino acid and divalent cation fluxes in gills of the bivalve mollusc, Mytilus californianus.

Effects of the deletion of Ca++, Mg++, or Ca++ and Mg++ on the leakage of primary amines, Ca++, and Mg++ from gills of Mytilus californianus were studied. In the absence of Ca++ the gills leak primary amines and Ca++ for about 30 minutes, after which the primary amines are reabsorbed. In the absence of Mg++ the gills leak primary amines, with no net reabsorption for at least 90 minutes, and show rapid leakage of Mg++. In the absence of both Ca++ and Mg++ amino acid leakage is initially less than in the absence of only one of the cations. Measurements of the kinetics of leakages of Ca++ and Mg++ are consistent with the hypothesis that both ions are associated with the cell surface, but the affinity of Ca++ for the cell surface is greater than that of Mg++. In the absence of Mg++, the influx of 14C-glycine was depressed to about 1/3 that seen in controls, while deletion of Ca++ had no effect on the rate of influx. Increasing the [Mg++] stepwise between 5 x 10(-6) and 1 x 10(-1) M results in a sigmoidal increase in the rate of influx of 14C-glycine and a hyperbolic increase in the y-intercept of influx curves.

Amino Acids↗
PubMed2001

Effect of an ac Perturbation on the Electroosmotic Behavior of a Cation-Exchange Membrane. Influence of the Cation Nature.

The effect of an ac sinusoidal perturbation of known amplitude and frequency superimposed on the usual dc applied electric voltage difference on the electroosmotic flow through a typical cation-exchange membrane has been studied using different monovalent electrolytes. As a general trend, the presence of the ac perturbation increases the value of the electroosmotic flow with respect to the value in the absence of ac perturbation. A dispersion of the electroosmotic permeability on the frequency of the applied ac signal has been found for the three studied electrolytes, observing that the electroosmotic permeability reaches maximum values for some characteristic values of the frequency. This behavior may be related to the different relaxation processes in heterogeneous mediums. Copyright 2001 Academic Press.

Journal Article↗
PubMed2002

Studies on exchange equilibria of cations between cation-exchange membranes and electrolytic solutions.

The variations of the selectivity coefficient K(A)(B) between Na(+)-H(+), Na(+)-K(+), and Na(+)-Cu(2+) systems and the separation factor alpha(A)(B) between Na(+)-Cu(2+) and K(+)-Cu(2+) systems in cation-exchange membranes as functions of loading and particle size of resin have been measured. The exchange affinities of all the membranes increase as H(+)<Na(+)<K(+)<Cu(2+). K(A)(B) is almost constant, independent of particle size and loading of resin in the membrane. Alpha(Na)(Cu) and alpha(K)(Cu) increase with decrease in particle size but remain almost constant with loading of resin in the membranes. The order of selectivity is K(Na)(H)<K(Na)(K)< or =K(Na)(Cu). The values of (alpha(A)(B)Q(0)(-1))(other)(alpha(A)(B)Q(0)(-1))(-1)(M(300)C60) for the Na(+)-Cu(2+) system are approximately 1.060 and for K(+)-Cu(2+) are approximately 0.870. Q(0) represents the exchange capacity of a dry membrane per unit volume (in milliequivalents per cubic centimeter).

Journal Article↗
PubMed1977

[Clinical significance of cationic proteins of leukocyte lysosomes: cationic leukocyte antigen (CLA) as a marker of blast crisis in chronic myelocytic leukaemia (author's transl)].

Cationic leukocyte antigen (CLA) was estimated in urine of acute and chronic leukaemics using quantitative immuno-precipitation techniques. The studies demonstrated that CLA is a marker of the (myelo-) blast crisis in patients with chronic myelocytic leukaemia (CML). By these studies the value of the determination of CLA for the differential diagnosis of acute myeloblastic leukaemia versus initial (myelo-) blast crisis in CML and the lymphatic leukaemias, respectively, was evident. The terminal blastic transformation in CML was indicated early by an elevation of the urinary CLA-level. The blast-crisis was accompanied by a heavy CLA-uria. The results are documented by demonstration of special studies of characteristic cases and discussed in the light of recent results of immunological and cytochemical findings on the nature of blast crisis in CML.

Aged↗
PubMed2004

Voltammetry of lead cations on a new type of silver composite electrode in the presence of other cations.

A new type of silver composite electrode was examined, prepared from silver, graphite powder, and methacrylate resin. The effects of the presence of various cations (cadmium, copper, bismuth, thallium), anions (chlorides), surface-active substances (Triton X-100), and oxygen on the anodic-stripping voltammetric determination of lead were studied. It was found that the effect of underpotential deposition at the composite electrode differs from that produced at a metallic silver electrode, mainly at low concentrations of the deposited metal. The use of this type of silver composite electrode in differential pulse anodic-stripping voltammetry enables direct determination of lead in natural water samples without elimination of surface-active substances (LOD about 3 microg L(-1)).

Journal Article↗
PubMed1987

Possible involvement of the 29 kDa protein in H+-ATPase in the action of cationic uncoupler of oxidative phosphorylation. Effect of the (o-phenanthroline)2-Cu2+ complex as a cationic uncoupler.

The divalent cation (o-phenanthroline)2-Cu2+ complex was found to uncouple oxidative phosphorylation in mitochondria. Its uncoupling activity depended on inorganic phosphate (Pi) in the incubation medium, and was inhibited by the SH-reagent N-ethylmaleimide, and retarded by ATP. The uncoupling by the (o-phenanthroline)2-Cu2+ complex was suggested to be due to its modification of sulfhydryl groups in the 29 kDa protein in H+-ATPase.

Animals↗
PubMed1992

Rat hepatocyte hyaluronan/glycosaminoglycan binding proteins: evidence for distinct divalent cation-independent and divalent cation-dependent activities.

We have previously shown (Biochemistry, 29, 10425, 1990) that hepatocytes contain intracellular specific binding sites for hyaluronan (HA). Although HA-binding activity is not dependent on divalent cations, it is increased in the presence of Ca+2. Here we report that a novel photoaffinity HA derivative (ASD-HA) crosslinks specifically to different proteins in permeable cells in the presence or absence of Ca+2. With Ca+2 present, two proteins of approximately 24 kD and 43 kD were labeled. Additionally, a broad zone of specific crosslinking was observed in the region of 40-100 kD. However, in the presence of the chelator EGTA this zone was absent and the 24 and 43 kD proteins were also not cross-linked to the HA photoaffinity derivative. In the absence of Ca+2, only a 54 kD protein was specifically labeled. The results indicate that different intracellular hepatocyte proteins are responsible for the Ca+2-independent and the Ca+2-dependent binding of HA.

Animals↗
PubMed1985

Effect of cations and cation channel blockers on human natural killer cells.

We studied the influence of various extracellular Ca++ and Mg++ concentrations on human natural killer (NK) cells and found that NK cell-mediated target cell lysis requires the presence of both divalent cations. The calcium channel blocker verapamil and the local anaesthetics procaine and lidocaine inhibited NK cell-mediated killing of K 562 target cells, whereas the selective K+ channel blocker tetraethylammonium and the selective Na+ channel blocker tetrodotoxin had no effect on NK activity. Our results demonstrate an important role of extracellular Ca++ and Mg++ for NK cell-mediated killing and suggest that a free transmembrane Ca++ passage is required for target cell lysis.

Anesthetics, Local↗
PubMed2004

A stable radical-substituted radical cation with strongly ferromagnetic interaction: nitronyl nitroxide-substituted 5,10-diphenyl-5,10-dihydrophenazine radical cation.

A stable radical-substituted radical ion with strongly ferromagnetic intramolecular interaction (J) between the radical and radical ion sites is an attractive spin building block of organic magnets. We prepared 2-nitronyl nitroxide-substituted 5,10-diphenyl-5,10-dihydrophenazine radical cation, 1+. The 1+ salt was stable under aerated conditions at room temperature and had a large J/kB value (>/=+700 K).

Journal Article↗
PubMed2000

Structure of cationized glycine, gly.m (m = be, mg, ca, sr, ba), in the gas phase: intrinsic effect of cation size on zwitterion stability.

Interactions between divalent metal ions and biomolecules are common both in solution and in the gas phase. Here, the intrinsic effect of divalent alkaline earth metal ions (Be, Mg, Ca, Sr, Ba) on the structure of glycine in the absence of solvent is examined. Results from both density functional and Moller-Plesset theories indicate that for all metal ions except beryllium, the salt-bridge form of the ion, in which glycine is a zwitterion, is between 5 and 12 kcal/mol more stable than the charge-solvated structure in which glycine is in its neutral form. For beryllium, the charge-solvated structure is 5-8 kcal/mol more stable than the salt-bridge structure. Thus, there is a dramatic change in the structure of glycine with increased metal cation size. Using a Hartree-Fock-based partitioning method, the interaction between the metal ion and glycine is separated into electrostatic, charge transfer and deformation components. The charge transfer interactions are more important for stabilizing the charge-solvated structure of glycine with beryllium relative to magnesium. In contrast, the difference in stability between the charge-solvated and salt-bridge structure for magnesium is mostly due to electrostatic interactions that favor formation of the salt-bridge structure. These results indicate that divalent metal ions dramatically influence the structure of this simplest amino acid in the gas phase.

Journal Article↗
PubMed2003

Bicyclo[2.2.1]hepta-2-ene-5-yl-7-ylium radical cation: a theoretical validation of a bishomoaromatic radical cation intermediate.

[structure: see text] A natural bond orbital analysis of the distonic bicyclo[2.2.1]hepta-2-ene-5-yl-7-ylium radical cation interprets its structure and radical character by a three-center two-electron bond between C2, C3, and C7 (a bishomoaromatic stabilization) and a singly occupied orbital on C5, n(5). Moreover, B3LYP/6-311+G(d,p) ESR parameters, which agree excellently with experiment, are interpreted in terms of spin polarization in the natural hybrids of sigma(C5-H5), and a dual hyperconjugative effect involving n(5), sigma(C1-H1a), sigma(C1-H1b), and antibonding counterparts.

Journal Article↗
PubMed2004

Cationic carbohydroxylation of alkenes and alkynes using the cation pool method.

The reactions of an N-acyliminium ion pool with alkenes and alkynes gave gamma-amino alcohols and beta-amino carbonyl compounds, respectively, after treatment with H(2)O/Et(3)N. The present reaction serves as an efficient method for cationic carbohydroxylation of alkenes and alkynes. When vinyltrimethylsilane was used as an alkene, the reaction was highly diastereoselective and served as an access to an enantiomerically pure alpha-silyl-gamma-amino alcohol. [reaction: see text]

Journal Article↗
PubMed1998

Gene transduction for disseminated intraperitoneal tumor using cationic liposomes containing non-histone chromatin proteins: cationic liposomal gene therapy of carcinomatosa.

Cationic liposome-mediated gene therapy of cancer has been examined in a disseminated intraperitoneal tumor model. A combination of the strong CAG promoter-enhancer unit and high mobility group 1,2 (HMG-1,2) proteins has been used to improve transfection efficiency. The optimal deoxyribonucleic acid (DNA) and HMG-1,2 concentration ratio was determined in in vitro studies. Subsequently, we administered the liposome-DNA-HMG-1,2 complex intraperitoneally to tumor bearing nude mice and defined the most efficient concentration of liposomes. Using this approach, the median survival of tumor bearing nude mice was prolonged by the administration of a human tumor necrosis factor-alpha (TNF-alpha) gene inserted into a eukaryotic strong expression vector (pcagTNF-alpha) and exogenously added interferon-gamma (INF-gamma) (72 +/- 3 days: mean +/- s.e.). By contrast, survival was 36 +/- 3, 39 +/- 3 and 46 +/- 4 days in group receiving the TNF-alpha gene inserted in the reverse orientation (pcagTNF-alpha R) and normal saline (NS), pcagTNF-alpha R and INF-gamma and pcagTNF-alpha and NS, respectively. These results demonstrate an efficient approach for gene therapy of disseminated intraperitoneal cancer.

Animals↗