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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This paper deals with the behavior of adult mouse bone marrow cells placed in tissue culture with or without antigen, and subsequently assessed for immune competence after adoptive transfer into lethally X-irradiated, syngeneic hosts. Attention was focussed on B lymphocytes through using hapten human gamma globulin (HGG) preparations as putative tolerogens in tissue culture, the T-cell-independent antigens DNP-POL and NIP-POL as challenge injections in adoptive hosts, and numbers of hapten-specific PFC in host spleens for the quantitation of immune competence. It was found that the capacity of bone marrow cells to mount an adoptive immune response rose by a factor of about fivefold over 3 days in tissue culture. This rise was completely abolished by the presence in the culture of hapten-HGG conjugates with about one mole of hapten per carrier molecule. The prevention of the emergence of immune competence amongst maturing B cells was termed clonal abortion tolerogenesis. Dose-response studies showed the lowest effective antigen concentration to be between 2.5 times 10- minus 10 and 2.5 times 10- minus 9 M, and a standard concentration of 2.5 times 10- minus 8 M was chosen as producing near maximal effects. The tolerance was antigen-specific and time-dependent, being maximal only when antigen was present continuously as the cultured cells was maturing. It did not depend on the presence of T lymphocytes in marrow, and was not of an "infectious" type. In contrast to tolerogenesis of mature B lymphocytes by high antigen concentrations, it could not be abolished by lipopolysaccharide. We speculate that clonal abortion may be a tolerance mechanism of great physiological significance for self-recognition, and discuss the results in the framework of other recent tolerance models, including those involving receptor blockade and suppressor T cells.
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PMID:Evidence for the clonal abortion theory of B-lymphocyte tolerance. 4 89

Studies were carried out to elucidate the nature of biphasic ATP hydrolysis by myosin at low temperature. 1. The rate of ATP splitting decreased sharply at 3--5 min after initiation of the reaction below a critical temperature (25 degrees and 30 degrees in the presence of Ca-2+ and EDTA, respectively). On the other hand, Mg-2+-ATPase [ED 3.6.1.3] did not exhibit such biphasic kinetics. 2. The Arrhenius plot of the second phase of the reaction after the rate transition gave a straight line whether the temperature of assay was above or below the critical one, giving 5.7 kcal/mole as the activation energy of Da-2+-ATPase showed features similar to those of Ca-2+-ATPase. 3. Michaelis constants for the two phases at 8 degrees were also different. In addition, the first phase of EDTA-ATPase was shown to have two different constants, depending on ATP concentration. 4. The profiles of the dependence of ATPase activity on KCl concentration were essentially the same for both phases, while bending of the time curve was scarecly observed obove pH 8 for Ca-2+-ATPase or at pH 6 for EDTA-ATPase. 5. 2, 4-Dinitrophenol abolished the phase transition for Ca-2+-ATPase and EDTA-ATPase, and heat treatment also minimized the transition for the former.
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PMID:Biphasic ATP splitting of myosin at low temperature. 12 18

The number of combining sites per mole of bovine colostral anti-DNP IgG2 was found to be 2 and the total affinity constant was 0.81 X 10(4) M-1. Unlike bovine colostral IgG1, the nonspecific binding of H3-epsilon-DNP-1-lysine by IgG2 as a function of increased concentrations, did not show a negative, cooperative slope. Spectral measurements made with anti-DNP IgG2 in the reference cell vs. anti-DNP IgG2 plus hapten in the experimental cell revealed a hypochromic, red shift from 363 to 365 nm. If the reference cell contained hapten, a red shift from 280 to 283 nm and an enhancement in the extinction coefficient of IgG2 was observed. These spectral changes were not observed if nonspecific IgG2 was substituted for anti-DNP IgG2 in the experimental cell. The enhancement in the extinction coefficient was interpreted to be due to a possible exposure of previously buried tryosine and tryptophan residues.
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PMID:Binding properties of bovine colostral anti-dinitrophenyl (dnp) immunoglobulins g2 (igg2). 99 4

N-Terminal analysis of purified buffalo thyroglobulin by the fluorodinitrobenzene method of Sanger yielded about 1.5 moles of DNP-glutamic acid per mole of buffalo thyroglobulin. No water-soluble DNP-amino acid was detectable as N-terminal. The presence of glutamic acid has been confirmed by Edman degradation and characterization of the PTH-amino acid in different solvent systems, and also after regeneration of free amino acid from PTH-amino acid in butanol-acetic acid-water (4:1:5, v/v) system. This is in contrast to the occurrence of aspartic acid or asparagine as N-terminals for several other mammalian thyroglobulins.
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PMID:N-terminal groups of buffalo thyroglobulin. 235 50

Water stress plating hypersensitivity was studied in two strains of Saccharomyces cerevisiae, one of them being a mutant incapable of accumulating trehalose to significant levels. The wild-type strain was grown in a defined medium with glucose, maltose or ethanol as carbon/energy source. In each case plating hypersensitivity was demonstrated and resistance to the stress developed in the second half of the exponential growth phase. Development of resistance was accompanied by accumulation of trehalose and was apparently unrelated to glycerol content which, under these conditions, was always low. A qualitatively similar trend was observed in the mutant grown on glucose but trehalose levels remained low and recovery of stress resistance was only slight. Dinitrophenol induced trehalose breakdown in resting yeast and simultaneously induced the onset of plating hypersensitivity. A negative correlation was demonstrated between trehalose content and 'plating discrepancy' (log colony count on 'normal' agar-log colony count on stressing agar) for both strains under all experimental conditions. The correlation held for trehalose contents up to about 50 mg (g dry yeast)-1, above which the yeasts were apparently fully resistant. Trehalose was evidently a more effective compatible solute, per mole, than glycerol.
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PMID:Water stress plating hypersensitivity of yeasts: protective role of trehalose in Saccharomyces cerevisiae. 306 53

2,4-Dinitrophenol, dicoumarol, carbonylcyanide, m-chlorophenyl-hydrazone and pentachlorophenol all depressed aerobic molar growth yields of Streptococcus agalactiae to values equal to, or less than, those supported by substrate level phosphorylation. When the only source of energy was from substrate phosphorylation (anaerobic growth conditions), there was also a severe depression of the molar growth yield by the same four uncoupling agents. These results indicate that the effect of these agents is to uncouple both substrate and oxidative phosphorylation in S. agalactiae. Amytal inhibited glucose utilization, reduced the amount of O(2) used per mole of substrate and reduced the molar cell yield to that supported by substrate phosphorylation. Atebrin inhibited the respiration rate, but final O(2) consumed per mole of substrate was unchanged, and the respiration was coupled to biosynthesis. Rotenone had no effect on respiration, substrate utilization, or on molar growth yields.
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PMID:Effect of uncoupling agents and respiratory inhibitors on the growth of Streptococcus agalactiae. 414 29

Equilibrium measurements of interactions of anti-DNP antibodies, prepared using DNP-PLL and several DNP-proteins for immunization, with DNP(0.6)-PLL(240) and with the univalent hapten, epsilon-DNP-L-lysine, were made utilizing the technique of fluorescence quenching. Carrier specificity of anti-DNP-PLL antibodies was demonstrated by a higher average intrinsic association constant (K(0)) of anti-DNP-PLL antibodies with DNP(0.6)-PLL(240) than with epsilon-DNP-L-lysine. The free energy contribution of the PLL carrier to the interaction of intact anti-DNP-PLL antibodies with DNP(0.6)-PLL(240) was from -0.8 to -2.1 kcal/mole. On the other hand, intact anti-DNP-protein antibodies displayed a lower energy of interaction with DNP(0.6)-PLL(240) than with epsilon-DNP-L-lysine of up to +2.4 kcal/mole. Fab' fragments of both anti-DNP-PLL and anti-DNP-BGG antibodies have K(0)'s with epsilon-DNP-L-lysine identical to the K(0)'s of the intact anti-DNP antibodies from which they were prepared. However, K(0) of interaction of Fab' fragments with DNP(0.6)-PLL(240) (a large proportion of the conjugated PLL molecules in this preparation bear more than one DNP group) is considerably lower than that of the intact antibody. Thus a cooperative effect in the binding of bivalent antibody and bivalent (or greater) antigen exists and is of the order of -1.2 to -2.0 kcal/mole of IgG antibody. Although the direct contribution of the carrier to the interaction of Fab' fragment of anti-DNP-PLL and DNP(0.6)-PLL(240) is -0.4 kcal/mole, the energy of carrier specificity, based upon consideration of cooperative effects and of repulsion of anti-DNP-protein antibodies for portions of the DNP-PLL determinants, is of the order of -3 kcal/mole (approximately 30% of total binding energy).
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PMID:Studies on the effect of the carrier molecule on antihapten antibody synthesis. II. Carrier specificity of anti-2,4-dinitrophenyl-poly-l-lysine antibodies. 416 Mar 99

1. The Mg content of axons obtained from Loligo forbesi averaged 6.4 +/- 0.8 m-mole/kg axoplasm.2. A small patch of radioactive (28)Mg injected into an axon broadened considerably. A similar patch of (45)Ca showed hardly any broadening. The self-diffusion coefficient of Mg in axoplasm is about 2 x 10(-6) cm(2)/sec which is at least twenty times greater than that of Ca.3. Under the influence of an applied electric field Mg migrated towards the cathode. Its mobility was about half of that of Mg in free solution. This suggests that the concentration of ionized Mg in squid axoplasm is between 2 and 3 m-mole/kg axoplasm. The mobility of Mg was not changed by poisoning the axon fully.4. Mg influx and Mg efflux were roughly the same and equal to about 1 p-mole/cm(2) sec. Mg efflux was reduced by poisoning with cyanide and by replacement of external Na by choline. Removal of external K or Ca had little effect and removal of external Mg tended to increase the efflux.5. The dependence of Mg efflux on Na seems not to be secondary to changes in Ca because it persists in the absence of external Ca and in axons pre-injected with EGTA. The form of the dependence on Na ions approximates to a simple rectangular hyperbola.6. Replacement of external Na by Li or choline increased Mg influx. Mg influx was unaffected by cyanide.7. Mg efflux was reduced to an average of 15% by poisoning with cyanide or DNP. The efflux could be recovered by injection of ATP. Inhibition persisted in axons pre-injected with EGTA, showing that it is not secondary to a rise in Ca(i).8. During nervous activity there is an extra entry of Mg. For axons immersed in sea water this extra Mg entry per impulse is roughly the same as the extra Ca entry per impulse.
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PMID:Mobility and transport of magnesium in squid giant axons. 465 Sep 39

1. The general characteristics and Na and K movements of L cells (derived from mouse epithelium) have been measured. Both cells grown in suspension (LS cells) and as a monolayer (L cells) were used.2. The volume of L cells was 1.2 x 10(-9) cm(3) and of LS cells 3.5 x 10(-9) cm(3); of this 82% was water.3. Electron micrographs showed the presence of numerous protrusions (filopodia) from both forms of the cell. These had the effect of increasing the surface area of the cell by 2-4 times over smooth cells of the same volume. On changing from the flattened to the spherical shape during trypsinization, the filopodia altered to maintain a constant V/A ratio.4. These cells contain K, about 170 m-mole/l. intracellular water and Na, 9 m-mole/l. intracellular water (L cells only) at 20 degrees C. The K fluxes are 1.9 p-mole/cm(2) sec for LS cells and 0.8 p-mole/cm(2) sec for L cells and the Na fluxes are 1.8 p-mole/cm(2) sec for L cells (expressed as per total cell surface (including filopodia)). If expressed as p-mole/cell per sec then L and LS cells have the same K flux.5. 10(-4)M ouabain reduces the K influx to half, indicating an insensitivity to the glycosides common to the species. In the prolonged presence of ouabain the cells come into a new steady state with a [K](1), of 140 and a [Na](1) of 20-30 m-mole/l. intracellular water, but a constant [Na + K](1).6. Both DNP (10(-3)M) and IAA (10(-4)M) are required for maximum inhibition of K uptake, as both aerobic and anaerobic metabolic pathways may be used to drive the pump.7. K removal decreases the Na efflux, and Na removal (eventually) decreases the K influx providing evidence for Na/K coupling.8. The cells contain 7.5 m-mole/litre intracellular water of ATP, a level some 15 times that of ADP.9. The Na pump in these cells is very similar to that found in other tissues in that (a) it requires K to work, (b) it is blocked by ouabain and metabolic inhibitors and (c) it transports three molecules of Na for each two molecules of K.
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PMID:Effect of ouabain and metabolic inhibitors on the Na and K movements and nucleotide contents of L cells. 510 32

1. The Ca movements in normal and ;ghost' L cells have been examined; all measurements were made using (45)Ca.2. Normal cells have a Ca concentration of about 1 m-mole/l. of cell volume, and exchange Ca in a complex way but with great rapidity; the time taken for the initial Ca(*) content to fall to half was less than 2 min.3. Poisoning normal cells with DNP 10(-3)M + IAA 10(-4)M causes a marked reduction in the Ca efflux, no change in Ca influx and an increase in total Ca.4. Variation in internal or external Na concentration does not alter the Ca fluxes or concentrations. Application of cyanide or ouabain and alteration of external K concentration had no effect on the Ca fluxes.5. The sulphydryl reagents, ethacrynic acid and N-ethylmaleimide (NEM), have a rapid and marked effect on reducing the Ca efflux.6. L cell ghosts previously poisoned with DNP+IAA have a low Ca efflux. When ATP or CTP is incorporated into such cells the Ca efflux becomes normal.7. An extra amount of phosphate is produced by L cell ghosts when pumping Ca. This is equivalent to the splitting of 1.8 moles of ATP per mole of Ca pumped.8. It is concluded that L cells have a Ca pump driven by ATP, and that Na has no effect on Ca movements in these cells.
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PMID:Effect of Na, metabolic inhibitors and ATP on Ca movements in L cells. 513 52


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