scholarly journals The asymmetry of the facilitated transfer system for hexoses in human red cells and the simple kinetics of a two component model

1973 ◽  
Vol 231 (1) ◽  
pp. 143-165 ◽  
Author(s):  
G. F. Baker ◽  
W. F. Widdas
Keyword(s):  
Red Cells ◽  
Component Model ◽  
Transfer System ◽  
Two Component ◽  
The Asymmetry ◽  
Kinetics Of ◽  
Human Red Cells

Acetylcholinesterase in Human Erythroid Cells

1973 ◽  
Vol 12 (3) ◽  
pp. 911-923
Author(s):  
R. J. SKAER
Keyword(s):  
Endoplasmic Reticulum ◽  
Nervous System ◽  
Golgi Apparatus ◽  
Red Cells ◽  
The Other ◽  
Red Cell ◽  
Erythroid Cells ◽  
Cell Replacement ◽  
Kinetics Of ◽  
Human Red Cells

Acetylcholinesterase is present in human red cells but cannot be demonstrated by the copper thiocholine test. The enzyme is revealed, however, in the perinuclear cisterna, endoplasmic reticulum and Golgi apparatus of red cell precursors. It is suggested that 2 forms of the enzyme are present, one of which can be demonstrated by the copper thiocholine test, the other cannot; one form may be the precursor of the other. These observations may cast light on the kinetics of red cell replacement and on the interpretation of the results from the copper thiocholine test on other tissues such as the nervous system.

scholarly journals K-Na EXCHANGE ACCOMPANYING THE PROLYTIC LOSS OF K FROM HUMAN RED CELLS

1947 ◽  
Vol 30 (5) ◽  
pp. 379-387 ◽  
Author(s):  
Eric Ponder
Keyword(s):  
Steady State ◽  
Cell Metabolism ◽  
Ionic Composition ◽  
Surface Membrane ◽  
Sodium Taurocholate ◽  
Red Cells ◽  
Red Cell ◽  
Membrane Changes ◽  
Kinetics Of ◽  
Human Red Cells

In systems containing human red cells and sodium taurocholate as a lysin, or distearyl lecithin as a sphering agent, the prolytic loss of K at 25°C. is accompanied by a gain of Na by the cell, the gain being somewhat greater than the K loss. A small volume increase accompanies the exchange. The kinetics of the K loss and the Na gain are similar to those already described; i.e., the changes are rapid at first, and slow down so that after 12 to 20 hours it appears that a new steady state is being approached. Similar, but smaller, losses of K and gains of Na occur when the cells stand in isotonic NaCl at 25°C. without the addition of a lysin or sphering agent. On these and other experimental grounds, it is impossible to retain the idea that the mammalian red cell in general is impermeable to cations. The cells nevertheless seem to be in a steady state with respect to their environment, their ionic composition changing as the composition of the environment is changed. The possible processes by means of which one steady state can be exchanged for another—changes in the permeability of a surface membrane, changes in the velocity of an active ion transfer process dependent on red cell metabolism, and changes in the activity of the ions in the red cell interior as a result of changes in an orderly internal structure—are discussed.

pH Dependent Hemolytic Systems. I. Their Relationship to Paroxysmal Nocturnal Hemoglobinuria

Blood ◽  
1961 ◽  
Vol 17 (1) ◽  
pp. 83-96 ◽  
Author(s):  
STANLEY YACHNIN ◽  
MITSUKO T. LAFORET ◽  
FRANK H. GARDNER
Keyword(s):  
Paroxysmal Nocturnal Hemoglobinuria ◽  
Proteolytic Enzymes ◽  
Red Cells ◽  
Red Cell ◽  
Cholera Vibrio ◽  
Normal Human ◽  
Ph Dependent ◽  
Kinetics Of ◽  
Insight Into ◽  
Human Red Cells

Abstract 1. Treatment of normal human red cells with various proteolytic enzymes, cholera vibrio filtrate, influenza virus, and periodate ion results in red cells susceptible to acid hemolysis in compatible normal human serum. 2. The kinetics of hemolysis of these artificially altered red cells resembles in many respects those observed in paroxysmal nocturnal hemoglobinuria (PNH). 3. While the observed differences in behavior between these artificially altered cells and PNH cells do not allow direct comparison, it is felt that these models may offer some clues in the understanding of PNH cell hemolysis, and some insight into the nature of the red cell lesion in paroxysmal nocturnal hemoglobinuria.

scholarly journals Kinetics of substrate hydrolysis and inhibition by mipafox of paraoxon-preinhibited hen brain esterase activity

1986 ◽  
Vol 236 (2) ◽  
pp. 503-507 ◽  
Author(s):  
C D Carrington ◽  
M B Abou-Donia
Keyword(s):  
Kinetic Parameters ◽  
Organophosphorus Compounds ◽  
Model Fit ◽  
Component Model ◽  
Low Concentrations ◽  
Two Component ◽  
High Concentrations ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Organophosphorus Inhibitor

For the purpose of assessing the neurotoxic potential of organophosphorus compounds, it has been determined that paraoxon-preinhibited hen brain has both neurotoxicant (mipafox)-sensitive (neurotoxic esterase; NTE) and -insensitive esterase components. Several experiments designed to investigate the kinetic parameters governing the reaction of these esterases with two substrates and one organophosphorus inhibitor are presented. First, kinetic parameters for the hydrolysis of phenyl valerate and phenyl phenylacetate were measured. At 37 degrees C, the Km values of NTE for phenyl valerate and phenyl phenylacetate were found to be about 1.4 × 10(-3) and 1.6 × 10(-4) M respectively. At 25 degrees C, the Km of NTE for phenyl valerate was determined to be about 2.4 × 10(-3) M. Secondly, the kinetic constants of NTE for mipafox were measured at both 25 degrees C and 37 degrees C. With either phenyl valerate or phenyl phenylacetate as substrate, the Km at 37 degrees C was determined to be about 1.8 × 10(-4) M, and the phosphorylation constant (k2) was about 1.1 min-1. For phenyl valerate only, the Km at 25 degrees C was found to be about 6 × 10(-4) M, and the k2 was about 0.7 min-1. The data obtained at 25 degrees C were analysed by using a two-component model without formation of Michaelis complex, a two-component model with formation of Michaelis complex on the second component (NTE), or a three-component model without formation of Michaelis complex. The fact that the Michaelis model fit the data significantly better than either of the other two models indicates that the higher apparent Ki values that occur with low concentrations of mipafox are due to formation of Michaelis complex at high concentrations, rather than because of the presence of two NTE isoenzymes, as has been suggested by other investigators.

The Effect of H2 Dilution on the Stability of a-Si:H based Solar Cells

1994 ◽  
Vol 336 ◽  
Author(s):  
Liyou Yang ◽  
Liang-Fan Chen
Keyword(s):  
Solar Cells ◽  
Substrate Temperature ◽  
Structural Properties ◽  
Recovery Process ◽  
The Other ◽  
Component Model ◽  
Device Stability ◽  
Two Component ◽  
The Stability ◽  
Kinetics Of

ABSTRACTWe have systematically investigated the effect of H2 dilution on the stability of a-Si:H based solar cells. The results clearly show that the device stability against light soaking improves substantially with increasing H2 dilution until a threshold is reached. Beyond this threshold which depends on the substrate temperature, the stability no longer changes with further increase in H2 dilution. On the other hand, at a given ratio of H2 to the reactant gases, the device stability generally improves with increasing substrate temperature. Multi-step light soaking experiments have shown that devices made with H2 dilution saturate much faster (∼100 hours) under one-sun illumination and exhibit little overshoot effect in the recovery process, in sharp contrast to devices made without H2 dilution. Based on the simple two-component model for defect kinetics, these observations and the fact that the apparent saturation time coincides with the time constant of the “fast” defects strongly suggest that negligible amount of “slow” defects exist in materials made with H2 dilution. While H2 dilution generally suppresses the formation of microstructure giving rise to dihydride bonding and microvoids, the differences in the kinetics of light induced degradation cannot always be traced to obvious differences in these structural properties.

In Vitro Assay of Platelet Adhesiveness with Washed and Tanned Human Red Cells

1968 ◽  
Vol 20 (03/04) ◽  
pp. 384-396 ◽  
Author(s):  
G Zbinden ◽  
S Tomlin
Keyword(s):  
Platelet Adhesion ◽  
Sodium Citrate ◽  
Blood Platelets ◽  
In Vitro Assay ◽  
Red Cells ◽  
Platelet Adhesiveness ◽  
Vitro Assay ◽  
In Vitro System ◽  
Human Red Cells

SummaryAn in vitro system is described in which adhesion of blood platelets to washed and tannic acid-treated red cells was assayed quantitatively by microscopic observation. ADP, epinephrine and TAME produced a reversible increase in platelet adhesiveness which was antagonized by AMP. With Evans blue, polyanetholsulfonate, phthalanilide NSC 38280, thrombin and heparin at concentrations above 1-4 u/ml the increase was irreversible. The ADP-induced increase in adhesiveness was inhibited by sodium citrate, EDTA, AMP, ATP and N-ethylmaleimide. EDTA, AMP and the SH-blocker N-ethylmaleimide also reduced spontaneous platelet adhesion to red cells. No significant effects were observed with adenosine, phenprocoumon, 5-HT, phthalanilide NSC 57155, various estrogens, progestogens and fatty acids, acetylsalicylic acid and similarly acting agents, hydroxylamine, glucose and KCN. The method may be useful for the screening of thrombogenic and antithrombotic properties of drugs.

Radiometric Chronology of Neh–nar Glacier, Kashmir

1982 ◽  
Vol 28 (98) ◽  
pp. 91-105 ◽  
Author(s):  
V. N. Nijampurkar ◽  
N. Bhandari ◽  
C. P. Vohra ◽  
V. Krishnan
Keyword(s):  
Average Rate ◽  
Component Model ◽  
Vertical Profiles ◽  
Kashmir Valley ◽  
Movement Rate ◽  
Accumulation Zone ◽  
Core Samples ◽  
Surface Samples ◽  
Two Component

AbstractSurface and core samples of Neh–nar Glacier in the Kashmir Valley have been analysed for the radionuclides 32Si. 210Pb, 40K, and 137Cs. The lateral and vertical profiles (at an altitude of about 4 140 m) reveal:(1)32Si activity decreasing slowly from the accumulation zone to 4 050 m altitude and then abruptly towards the snout.(2)Five zones of alternating high and low 210Pb activity in the surface samples.(3)An horizon at between 2 and 3 m depth containing 210Pb activity above natural levels. This horizon is also associated with 137Cs and a maximum in total ß activity.The ice samples have been dated on the basis of a simplified two–component model, the “fresh“contribution determined by 2l0Pb and the old component by 32Si. The following conclusions can be drawn from these observations:(1)The model age of the snout ice is c. 850 years.(2)The average rate of ice movement in the lower glacier is about 2 m/year, which compares well with the annual movement rate of 2.65 m/year observed since 1974.

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