STAPHYLOCOCCAL TOXINS: II. FACTORS AFFECTING HEMOLYSIS BY δ-LYSIN

1958 ◽  
Vol 4 (5) ◽  
pp. 435-444 ◽  
Author(s):  
A. W. Jackson ◽  
R. M. Little
Keyword(s):  
Human Erythrocytes ◽  
Magnesium Ions ◽  
Erythrocyte Ghosts ◽  
Factors Affecting ◽  
Early Stages

The influence of a number of variables upon lysis of erythrocytes by staphylococcal δ-lysin has been examined. Hemolysis of human erythrocytes by δ-lysin has been found to be unaffected by the presence of α-lysin but is inhibited by a number of proteins, serum being the most active of those tested. Glucose, citrate, and magnesium ions were found to have no effect on hemolysis by δ-lysin. Hemoglobin and erythrocyte ghosts were inhibitory. Release of cell constituents during hemolysis is considered to be partly responsible for the change from a rapid to a slower rate of hemolysis in the early stages of the reaction.It was found that the extent of hemolysis of a 1% suspension of human erythrocytes is linearly related to lysin concentration provided lysis is not greater than 65% nor less than 30% of total hemolysis. A method of determining relative δ-lysin activity is described.

Further Studies upon Chemical Factors Affecting the Breeding of Anopheles in Trinidad

1934 ◽  
Vol 25 (4) ◽  
pp. 491-494 ◽  
Author(s):  
P. A. Buxton
Keyword(s):  
Analytical Study ◽  
Chemical Constituents ◽  
Physical Factors ◽  
Factors Affecting ◽  
Early Stages ◽  
Freshwater Biology ◽  
Chemical Technique ◽  
Chemical Factors ◽  
Physical And Chemical

During the last decade, entomologists have made progress in understanding the environment in which certain insects live; in particular, we begin to understand the effect of certain physical and chemical factors, which make up a part of the environment. With this gain in knowledge, it is sometimes possible to forecast outbreaks of insects and of diseases conveyed by them, and one can sometimes say that a particular alteration of the environment will result in loss or gain. But so far as mosquitos are concerned, one must admit that though much work has been devoted to the analytical study of the water in which the early stages are passed, the results are disappointing. A consideration of the published work suggests several reasons for this. Investigation into the ecology of the mosquito has had a vogue, and much of it has been done by workers who were isolated and whose knowledge of chemical technique and freshwater biology was limited. Apart from that, the inherent difficulties are great, for the worker must hunt for the limiting chemical and physical factors among a host of others which are doubtless unimportant, and there are few clues to indicate which of the chemical constituents of the water affects the mosquito. The data are therefore voluminous and it is difficult to reduce them to order and present them so that they can be readily understood.

scholarly journals Factors affecting the amount and the mode of merocyanine 540 binding to the membrane of human erythrocytes. A comparison with the binding to leukemia cells

1995 ◽  
Vol 1235 (2) ◽  
pp. 428-436 ◽  
Author(s):  
Johan W.M. Lagerberg ◽  
Karl-Josef Kallen ◽  
Cees W.M. Haest ◽  
John VanSteveninck ◽  
Tom M.A.R. Dubbelman
Keyword(s):  
Human Erythrocytes ◽  
Leukemia Cells ◽  
Factors Affecting ◽  
Merocyanine 540

Lead and calcium transport in human erythrocyte

1999 ◽  
Vol 18 (5) ◽  
pp. 327-332 ◽  
Author(s):  
J V Calderón-Salinas ◽  
M A Quintanar-Escorcia ◽  
M T González-Martínez ◽  
C E Hernández-Luna
Keyword(s):  
Transport System ◽  
Human Erythrocyte ◽  
Calcium Transport ◽  
Human Erythrocytes ◽  
The Other ◽  
Erythrocyte Ghosts ◽  
Passive Transport ◽  
Ca Uptake

In this paper we report the lead (Pb) and calcium (Ca) uptake by erythrocyte ghosts. In both cases the transport was carried out by a passive transport system with two kinetic components (Michaelis-Menten and Hill). Pb and Ca were capable of inhibiting the transport of the other metal in a non-competitive way. Under hyperpolarization, the uptakes of Ca and Pb were enhanced and the Michaelis-Menten component prevailed. Both Ca and Pb uptakes were inhibited by N-ethyl-maleimide to the same extent. These results indicate that Pb and Ca share the same permeability pathway in human erythrocytes and that this transport system is electrogenic.

The mobility of intramembrane particles in non-haemolysed human erythrocytes. Factors affecting acridine-orange-induced particle aggregation

1986 ◽  
Vol 86 (1) ◽  
pp. 57-67
Author(s):  
G. Lelkes ◽  
I. Fodor ◽  
G. Lelkes ◽  
S.R. Hollan
Keyword(s):  
Acridine Orange ◽  
Intracellular Ph ◽  
Lateral Diffusion ◽  
Inhibitory Effect ◽  
Human Erythrocytes ◽  
Particle Aggregation ◽  
Experimental Conditions ◽  
Factors Affecting ◽  
Cross Links ◽  
Phosphate Buffered Saline

It has previously been shown that reversible intramembrane particle aggregation can be induced in non-haemolysed human erythrocytes. This phenomenon, which can be induced by the cationic dye Acridine Orange, has been further investigated using different experimental conditions that are expected to influence the rate of aggregation of the particles. In addition to the concentration of the dye, the rate of aggregation was also found to be dependent on the extracellular and intracellular pH, as well as on the type of buffer used. While lowering the pH of the Acridine Orange solutions resulted in decreased particle clustering, low intracellular pH increased and elevated intracellular pH decreased particle aggregation. Furthermore, at a given dye concentration and a given pH, Acridine Orange caused more intense aggregation in Tris-buffered saline than in isotonic phosphate buffer or phosphate-buffered saline. Under appropriate conditions Acridine Orange caused significant particle aggregation at concentrations as low as 0.25 mM within 30 s. During this period only discocyte-stomatocyte transformation occurred; neither agglutination nor vesiculation of the erythrocytes could be detected. Treatment of the erythrocytes with Diamide (Serva), which cross-links spectrin via disulphide bridges and thereby reduces lateral diffusion of integral membrane proteins over large distances, had no inhibitory effect on Acridine-Orange-induced particle aggregation. Heating the erythrocytes to 50 degrees C, at which temperature denaturation of spectrin and fragmentation of the erythrocytes occur, and subsequently incubating them in Acridine Orange at room temperature, caused an almost maximal rate of particle aggregation within 10–30 s, without haemolysis. The possible mechanism and significance of the particle aggregation phenomenon are discussed.

Capture and evaluation of innovative ideas in early stages of product development

2019 ◽  
Vol 31 (6) ◽  
pp. 908-927 ◽  
Author(s):  
Peter Madzík
Keyword(s):  
Product Development ◽  
Innovation Process ◽  
Kano Model ◽  
Effect Analysis ◽  
Content Type ◽  
Factors Affecting ◽  
Early Stages ◽  
Structured Analysis ◽  
Idea Evaluation

Purpose The purpose of this paper is to propose a structured procedure for the capture and evaluation of innovative ideas in the early stages of product development. The procedure is designed to take account of internal and external factors affecting the value of innovative ideas. Design/methodology/approach The proposed procedure is based on divergent and convergent approaches to innovation. Ideas are generated and captured using targeted questions and subsequently evaluated using modifications of the Kano model and failure mode and effect analysis (FMEA). Idea evaluation considers four criteria – delight, originality, market share potential and simplicity – which are used to compute an “idea priority number”. Findings A case study looking at innovations in swimming goggles verified the validity of the proposed procedure. The procedure also supports fact-based decision making and applies a structured perspective to the innovation process that makes it easier to manage. Research limitations/implications The case study made use of a pilot survey in which 32 customers participated. Although the case study was only intended as a demonstration of the method’s use, such a sample size could lead to unreliable results in certain cases. Originality/value Applications of standard or expanded FMEA do not add value to a product because the main purpose of the approach is to prevent failure. The proposed inversion of FMEA logic combined with customer view via the Kano model offers a method for the structured analysis of product innovations. No similar approach to the evaluation of innovations has so far appeared in the literature.

scholarly journals Evidence that the uptake of tri-iodo-l-thyronine by human erythrocytes is carrier-mediated but not energy-dependent

1982 ◽  
Vol 208 (1) ◽  
pp. 27-34 ◽  
Author(s):  
Roelof Docter ◽  
Eric P. Krenning ◽  
Greetje Bos ◽  
Durk F. Fekkes ◽  
George Hennemann
Keyword(s):  
Contrast Agents ◽  
Rat Hepatocytes ◽  
Human Erythrocytes ◽  
Uptake System ◽  
Erythrocyte Ghosts ◽  
Intact Cells ◽  
X Ray ◽  
Dose Dependent Fashion ◽  
Uptake Studies ◽  
Energy Dependent

We investigated 3,3′,5-tri-iodo-l-thyronine transport by human erythrocytes and by ‘ghosts’ prepared from these cells. Uptake of tri-iodothyronine by erythrocytes at 37°C was time-dependent with a maximum reached after 60min. Tracer analysis after incubation for 1min revealed only one saturable binding site, with Km 128±19nm (mean±s.e.m.; n=7) and Vmax. 4.6±0.7pmol of tri-iodothyronine/min per 6×107 cells. After 10min incubation Km 100±16nm (n=10) was found with Vmax. 7.7±1.2pmol of tri-iodothyronine/10min per 6×107 cells. At 0°C the uptake system is still active, with Km 132±26nm and Vmax. 1.8±0.3pmol of tri-iodothyronine/10min per 6×107 cells. The Vmax. with intact cells is 5-fold greater than the Vmax. with membranes derived from the same amount of cells when uptake studies are performed in media with similar free tri-iodothyronine concentrations. This indicates that at least 80% of tri-iodothyronine taken up by the intact erythrocytes enters the cell. This saturable uptake system can be inhibited by X-ray-contrast agents in a dose-dependent fashion. (±)-Propranolol, but not atenolol, has the same effect, indicating that the membrane-stabilizing properties of (±)-propranolol are involved. Furthermore, there is no inhibition by ouabain or vanadate, which indicates that tri-iodothyronine uptake is not dependent on the activity of Na++K+-dependent adenosine triphosphatase. We have prepared erythrocyte ‘ghosts‘, resealed after 2.5min with 0mm-, 2mm- or 4mm-ATP inside. Inclusion of ATP and integrity of the membrane of the erythrocyte ‘ghosts’ were verified on the basis of an ATP-concentration-dependent functioning of the Ca2+ pump. No difference was found in the uptake of tri-iodothyronine by erythrocyte ‘ghosts’ with or without ATP included, indicating that uptake of tri-iodothyronine is not ATP-dependent. The following conclusions are drawn. (1) Tri-iodothyronine enters human erythrocytes. (2) There is only one saturable uptake system present for tri-iodothyronine, which is neither energy (i.e. ATP)-dependent nor influenced by the absence of an Na+ gradient across the plasma membrane. This mode of uptake of tri-iodothyronine by human erythrocytes is in sharp contrast with that of rat hepatocytes, which uptake system is energy-dependent and ouabain-sensitive [Krenning, Docter, Bernard, Visser & Hennemann (1978) FEBS Lett.91, 113–116; Krenning, Docter, Bernard, Visser & Hennemann (1980) FEBS Lett.119, 279–282]. (3) X-ray-contrast agents inhibit tri-iodothyronine uptake by erythrocytes in a similar fashion to that by which they inhibit the uptake of tri-iodothyronine by rat hepatocytes [Krenning, Docter, Bernard, Visser & Hennemann (1982) FEBS Lett.140, 229–233].

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