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At least 595 records · Page 33Linked to original sources
PubMed1995

Influence of method of administration of rapeseed oil in dairy cows. 2. Status of divalent cations.

The effects of method of administration of rapeseed oil on total, soluble, and ionizable Ca and Mg in ruminal fluid were determined for four diary cows fed a basal diet without (control) or with rapeseed oil (1 kg/d) added by continuous infusion or by a single administration via the ruminal cannula. The control diet contained 68% forage and 32% concentrate mix (DM basis). Fatty acid, Ca, and Mg contents, respectively, were 1.78, 1.16, and .47% for the control diet and 7.38, 1.05, and .44% for the supplemented diets. Soluble and ionizable Ca and Mg concentrations of ruminal fluid and the total Ca, Mg, and soaps of fatty acids in ruminal contents were determined over 24 h. All concentrations except total Ca varied with sampling time. All contents of soluble and ionizable Ca were decreased by lipid supplementation. A lack of ionizable Ca may limit the attachment of bacteria to particles, thus reducing ruminal digestion. In contrast, variations of Mg from lipid supply were lower than those of Ca. The interaction between time and diet was significant for soluble and ionizable Ca contents of ruminal fluid. Diurnal variation of these components was not associated with variations in the estimated soaps of fatty acids.

Animals↗
PubMed1976

Effects of divalent cations on vitamin B12 adsorption to brush borders of rat intestine.

A brush border preparation from rat intestine was incubated with rat intrinsic factor-vitamin B12 complex in 0.01 M Tris-HCl buffer, pH 7.4. The 57Co-B12 uptake to brush borders was proportional to the amount of protein or to alkaline phosphatase activity in the preparations. The uptake increased with time of incubation. At 37degreesC, the uptake after incubation for 15 min was 80-85% of that for one hr. The uptake at 4degreesC was approximately 70% of that at 37degreesC. Ther was no difference as a result of adding glucose to the incubation medium. The uptake was observed in the alkaline environment above pH 6.3. Maximum uptake occurred at pH 8.0. Brush borders washed with Krebs-Ringer bicarbonate buffer (pH 7.4) exhibited no difference in B12 uptake, whether in the presence or absence of calcium ion. But brush borders washed with ethylenediaminetetraacetate exhibited no uptake when incubated in calcium-free medium. The uptake reached a maximum by addition of calcium ion at a concentration of 0.3 mM, and was not alter up to 10 mM. Addition of magnesium ion exhibited no uptake. Calcium-dependent B12 uptake was markedly inhibited by manganese ion. Magnesium ion seemed to slightly inhibit the calcium-dependent uptake.

Adsorption↗
PubMed1978

Polycation-induced dislocation of slit diaphragms and formation of cell junctions in rat kidney glomeruli: the effects of low temperature, divalent cations, colchicine, and cytochalasin B.

Neutralization of negatively charged groups in the glomerular capillary wall by polycations causes extensive loss of podocyte footplates, formation of tight and gap junctions, and dislocation of slit diaphragms within a few minutes (M. W. Seiler, M. A. Venkatachalam, and R. S. Cotran: Science 189:390, 1975). This study attempts to elucidate further the development of podocyte abnormalities by quantitating the effects of inhibitors of microfilaments, microtubules, and cellular metabolism. The decrease in the number of footplates per micrometer of basement membrane caused by the polycationic chemical protamine sulfate (PS) was determined after in situ perfusion of the left kidney of rats. An approximate 50 per cent amelioration of this effect of PS was observed when in addition to perfusion with PS: (1) perfusion was performed in the cold (6 degrees C.); (2) the perfusate contained cytochalasin B; (3) the perfusate lacked Ca2+; and (4) the perfusate contained ethylenediaminetetraacetic acid. In contrast, colchicine did not affect PS-induced footplate loss. It was concluded that the PS-induced footplate retraction observed in scanning micrographs, is partially an active process involving podocyte actin filaments. Intact microtubuli are obviously not necessary. Formation of tight and gap junctions between foot processes and dislocation of slit diaphragms were not influenced by any of the inhibitory conditions listed above.

Animals↗
PubMed1999

[The effect of divalent cations on pepsinogen extrusion by permeable isolated gastric glands].

The model of permeable gastric glands obtained by its incubation with digiton (15 mg/ml) had investigated. It was shown, that stimulated influence of Ca2+ ions on pepsinogen extrusion completely or partly reproduced by cations of transient metals. Stimulated effects of cations of metals (5 x 10(-4) M) decrease in such order: Ca2+ > Cd2+ > Mn2+ > Co2+ > La3+. Nevertheless, Co2+ and La3+ in the same concentrations inhibit Ca2+ stimulated extrusion of pepsinogen by permeable isolated glands. Stimulated effect of Cd2+ and La3+ on pepsinogen extrusion in native glands was not reproducible. Besides these cations inhibit carbacholine-stimulated extrusion in native glands. It's concluded, that influence of metal cations on secretory function of gastric glands to a great extent is determined by their property to penetrate into secretory cells and cooperate with their plasma membranes.

Animals↗
PubMedDate not supplied

Partial dependence of human peripheral blood leukocyte binding to high molecular weight fucoidan on divalent cations.

L-selectin (CD62L) is the principal leukocyte adhesion molecule for the high endothelial venules of peripheral lymph nodes. This adhesion has an absolute requirement for calcium ions. Nevertheless, some studies have shown carbohydrate adhesion receptor interactions on lymphocytes and neutrophils, including the L-selectin molecule, that are Ca-independent. In the present study fucoidan, a reportedly Ca2+ independent ligand of L-selectin, and Mabs to human CD62L were coupled to magnetic polystyrene beads (MPB), as a model of leukocyte-surface interactions, and the efficiency of human leukocyte separation was investigated. 30% of Ficoll-purified human mononuclear cells and 75% of dextran-purified human leukocytes (DPHL) were specifically bound by fucoidan-modified MPB in the presence of Ca2+; 55% of dextran-purified leukocytes were specifically bound in the absence of Ca2+. The specific binding was inhibited by an excess of free fucoidan. The data obtained show the presence of Ca-independent adhesion determinants, specific to fucoidan on human leukocytes. No significant specific binding of leukocytes to fucoidan-modified MPB was found after the incubation with fresh human Ca(2+)-depleted whole blood. More than 90% of DPHL were specifically bound to MPB modified with Mabs to human CD62L irrespective of Ca2+ presence. The same degree of separation was achieved after the incubation with fresh human Ca(2+)-depleted-whole blood with anti-CD62L modified beads.

Adult↗
PubMedDate not supplied

[Effect of the mitochondrial ionophore for divalent cations on bilayer phospholipid membranes].

It has been shown that ionophore of bivalent cations (IBC) isolated from fatless, subjected to partial triptic hydrolysis cattle heart or liver mitochondria decreases BPM resistance inducing Ca2+ conductivity. Ions of lanthane in micromolar concentrations decrease calcium conductivity induced with IBC. When ten-fold gradient in Ca2+ was created on BPM the intitiation of the membrane potential fo 9-11 mV was observed. The role fo IBC and water soluble factors binding Ca2+ with high affinity, in the mitochrondial mechanism of Ca2+ translocation is discussed.

Animals↗
PubMed1975

Effects of divalent cations, cation chelators and an ionophore on morphine analgesia and tolerance.

The analgesic effect of morphine was antagonized in mice by intracerebroventricular injection of Ca++, Mg++ and Mn++ and was potentiated by ethylene glycol tetraacetic acid but was not altered by Sr++, Ba++, Ni++, Hg++, Cd++ or ethylenediamine tetraacetic acid. The antagonistic effect of Ca++ was not altered by pretreatment with pargyline or 6-hydroxydopamine indicating that altered release of catecholamines or serotonin was not involved in this action of Ca++. Induction of morphine tolerance by pellet implantation also did not alter the antagonistic effect of Ca++. The antagonistic effects of Ca++ and naloxone were additive in both nontolerant and tolerant animals and the apparent affinity of naloxone for its receptors, as estimated by in vivo pA2 determinations, was not altered by Ca++. However, the ionophore X537A was found to increase greatly the narcotic antagonist effect of a low dose of Ca++ although the ionophore alone did not alter the effects of morphine. This indicates that Ca"++ must penetrate cell membranes in order to reduce the analgesic effects of morphine. These findings indicate the importance of Ca++ localization in the actions of narcotic agonists and antagonists.

Analgesia↗
PubMed1979

The bovine immune response to Brucella abortus. II. Elimination of some sporadic serological reactions by chelation of divalent cations.

The standard agglutination tests for detecting antibody to Brucella abortus were modified by addition of chelating agents (EDTA and EGTA) to the antigens. Approximately 80% of "singleton" agglutination test reactions, negative on the diagnostic complement fixation test, obtained with cattle sera were eliminated while no decrease in titer was apparent when sera from B. abortus infected or vaccinated cattle were tested.

Agglutination Tests↗
PubMedDate not supplied

[Binding of divalent cations with low density lipoproteins. A study by ESR].

The binding of bivalent metal ions Cu2+, Zn2+, Ca2+, Mg2+ to low-density lipoproteins (LDL) was investigated by the ESR technique. The monitoring of ESR spectra of paramagnetic Mn2+ ions in the presence of above-listed cations made it possible to evaluate the dissociation constants of their complexes with LDL. The effective dissociation constant of the complex Mn(2+)-LDL used for calculations was KD = (1.1 +/- 0.4) x 10(-4) M according to literature data. The investigated cations may be classified into two groups: 1) low dissociation constants were characteristic for Cu2+ ions [KD = (1.3 +/- 0.5) x 10(-4) M], which demonstrated a high oxidative ability, and for Zn2+ [KD = (0.95 +/- 0.45) x 10(-4) M] and Mn2+ ions, which could strongly influence the copper-induced LDL oxidation; 2) Ca2+ and Mg2+ were characterized by higher values of KD [(6 +/- 1) x 10(-4) M and (7.5 +/- 1.5) x 10(-4) M, accordingly] and slightly affected the Cu(2+)-induced oxidation of LDL. The results of the present work reinforced our earlier conjecture that cations may influence the process of lipid peroxidation, binding only to particular binding sites on the surface of LDL.

Algorithms↗
PubMedDate not supplied

[Oocyte maturation and activation in the common frog and the clawed toad under the action of divalent cations].

Maturation of Rana temporaria and Xenopus laevis oocytes was induced by solutions containing Mn2+ and Co2+ ions. Completion of oocyte maturation was estimated by the following criteria: (1) appearance of the maturation promoting factor (MPF) in the oocyte cytoplasm and (2) oocyte capacity to activation and formation of male pronuclei from the injected sperm nuclei. X. laevis oocytes matured under the effect of Co2+ ions were shown to contain MPF. Oocytes of both species matured under the effect of either ions could not be activated by pricking with a needle and injected sperm nuclei didn't transform into pronuclei. R. temporaria oocytes matured under the effect of ions in late spring, when natural spawning takes place, showed spontaneous activation.

Animals↗