Platelets in Animals

Maupin, B

doi:10.1016/b978-1-4832-8297-8.50019-6

Cited by 13 publications

(18 citation statements)

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“…The data also support the view that the high platelet content of endogenous taurine described previously by Frendo et al (1959) and Maupin (1969) and confirmed again here, may involve the operation in vivo of the taurine transport mechanism that we have studied in vitro.…”

Section: Discussionsupporting

confidence: 92%

“…Boullin, Votavova & Green (1972) showed that arginine and leucine transport is dramatically reduced by the addition of 19 other amino acids to the Krebs solution in concentrations of 20 nmol/ml. Although in our case we were unable to detect taurine in the plasma, Maupin (1969) (O'Brien & Boullin, 1974). Another possibility that applies particularly to amino acid transport concerns the multiplicity of transport systems involved.…”

Section: Discussionmentioning

confidence: 58%

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Transport of Taurine by Normal Human Blood Platelets

Ahtee

Boullin

Paasonen

1974

British J Pharmacology

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Because normal human blood platelets contain higher concentrations of taurine than any other amino acid, and have a platelet: plasma concentration gradient exceeding 400:1, we isolated the cells in vitro and incubated them with radioactively labelled taurine in order to investigate the existence of a metabolically‐dependent accumulation process. Platelets incubated with taurine (1 to 100 nmol/ml) in autologous plasma or Krebs solution accumulated [14C]‐taurine against the concentration gradient. The transport process was saturable at high concentrations, showed a requirement for sodium ions, and was temperature‐dependent. The kinetics of transport fulfilled the criteria of Michaelis & Menten for saturable enzyme/substrate interactions, but the kinetic constants were influenced by the incubation medium. The metabolic inhibitors 2,4‐dinitrophenol and iodoacetic acid in combination inhibited taurine transport in Krebs solution, but stimulated transport in autologous plasma. The latter result suggested the involvement of a sodium‐dependent ATPase in taurine transport. We conclude that platelets actively transport taurine in vitro under experimental conditions closely resembling those likely to occur in vivo, and that this taurine transport process may be involved in the maintenance of the platelet: plasma concentration gradient.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 58%

Transport of Taurine by Normal Human Blood Platelets

Ahtee

Boullin

Paasonen

1974

British J Pharmacology

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“…The basis of contraction in microfilament systems is still hypothetical. Contraction of glycerol-extracted cells in response to adenosine triphosphate (53), extraction of actin-like or actomyosin-like proteins from cells other than muscle cells (54), and identification of activity resembling that of the actomyosin-adenosinetriphosphatase system in a variety of nonmuscle tissues (40,54) are consistent with the idea that portions of the complex, striated muscle contractile system may be pres.. ent in more primitive contractile machinery. In the case of the egg cortex, calcium-activated contractions can be inhibited by cytochalasin.…”

Section: Discussionmentioning

confidence: 59%

“…After the blood in higher vertebrates undergoes the initial clotting reaction a process of clot retraction takes place (40). This phenomenon has been attributed to the contractile protein thrombosthenin located within the blood platelets.…”

Section: Other Biological Effects Of Cytochalasinmentioning

confidence: 99%

Microfilaments in Cellular and Developmental Processes

Wessells

Spooner

Ash

et al. 1971

Science

1,463

326

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In our opinion, all of the phenomena that are inhibited by cytochalasin can be thought of as resulting from contractile activity of cellular organelles. Smooth muscle contraction, clot retraction, beat of heart cells, and shortening of the tadpole tail are all cases in which no argument of substance for alternative causes can be offered. The morphogenetic processes in epithelia, contractile ring function during cytokinesis, migration of cells on a substratum, and streaming in plant cells can be explained most simply on the basis of contractility being the causal event in each process. The many similarities between the latter cases and the former ones in which contraction is certain argue for that conclusion. For instance, platelets probably contract, possess a microfilament network, and behave like undulating membrane organelles. Migrating cells possess undulating membranes and contain a similar network. It is very likely, therefore, that their network is also contractile. In all of the cases that have been examined so far, microfilaments of some type are observed in the cells; furthermore, those filaments are at points where contractility could cause the respective phenomenon. The correlations from the cytochalasin experiments greatly strengthen the case; microfilaments are present in control and "recovered" cells and respective biological phenomena take place in such cells; microfilaments are absent or altered in treated cells and the phenomena do not occur. The evidence seems overwhelming that microfilaments are the contractile machinery of nonmuscle cells. The argument is further strengthened if we reconsider the list of processes insensitive to cytochalasin (Table 2). Microtubules and their sidearms, plasma membrane, or synthetic machinery of cells are presumed to be responsible for such processes, and colchicine, membrane-active drugs, or inhibitors of protein synthesis are effective at inhibiting the respective phenomena. These chemical agents would not necessarily be expected to affect contractile apparatuses over short periods of time, they either do not or only secondarily interfere with the processes sensitive to cytochalasin (Table 1). It is particularly noteworthy in this context that microtubules are classed as being insensitive to cytochalasin and so are not considered as members of the "contractile microfilament" family. The overall conclusion is that a broad spectrum of cellular and developmental processes are caused by contractile apparatuses that have at least the common feature of being sensitive to cytochalasin. Schroeder's important insight (3) has, then, led to the use of cytochalasin as a diagnostic tool for such contracile activity: the prediction is that sensitivity to the drug implies presence of some type of contractile microfilament system. Only further work will define the limits of confidence to be placed upon such diagnoses. The basis of contraction in microfilament systems is still hypothetical. Contraction of glycerol-extracted cells in response to adenosine triphosphate (53), ex...

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“…Since then Received for publication 8 December 1971. 218 modifications have been made to older methods and additional newer methods have been introduced so that the number of techniques now available exceeds 160 (Maupin, 1969). This proliferation of methods proves the inadequacy of available techniques and also stresses the need for improved systems.…”

mentioning

confidence: 99%

Evaluation of an automatic platelet counting system utilizing whole blood

1972

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SYNOPSIS Technicon's newly developed platelet AutoCounter utilizes an electro-optical systemwhich detects and counts particles by sensing the scattering of light which occurs when blood cells flow through the illuminated sensing chamber of a micro-optical system. The system utilizes whole blood collected into EDTA. Blood samples, which can be handled at the rate of 40 per hour, are diluted with 2M urea which in addition causes lysis of the erythrocytes. The haemolysate thus obtained is delivered to the particle counter after a two-minute reaction time, the cell count finally being displayed on a continuous chart recorder.An evaluation of this machine has been carried out in the Department of Haematology, the Royal Infirmary, Edinburgh, on hospital specimens from patients suffering from a wide variety of diseases. The results of this evaluation are presented. Reproducibility studies indicate a coefficient of variation of 4 % at any platelet level. The percentage drift per sample ranges from + 04 to -0-4 % of the total count. Carry-over and departures from linearity are statistically significant; however, the magnitude of these deviations is not sufficient to cause concern in routine use. Acceptable agreement is noted between machine counts and the counts obtained by technicians using phasecontrast microscopy with the exception of two anomalous individuals.Discrepant counts were noted in patients with elevation of the erythrocyte sedimentation rate and also in patients with disturbance of immunoglobulins. A modification to the sampling probe which eliminates the former problem is described.The AutoCounter described in this paper provides a fast, reliable, and accurate service laboratory platelet counting system.Morphological and numerical evaluation of formed blood elements constitutes useful guidance in the assessment of normal and disturbed haemopoietic function. Because of increasing interest in automation of the haematology laboratory there is need for a parallel increase in cooperation between the haematologist and the automated instrument designer in order that each may gain insight into the other's problems. Already automation procedures in haematology are well established with respect to red and white cell counting (Nelson, 1969;Barnard, Carter, Crosland-Taylor, and Stewart, 1969) (Maupin, 1969). This proliferation of methods proves the inadequacy of available techniques and also stresses the need for improved systems.Direct counting methods involve the absolute enumeration of platelets in a suitable solution and thus the platelet count is not related to a second known quantity of formed elements as was the practice with now discarded indirect methods of platelet counting. Examples of direct counting methods in current use include (1) light or phasecontrast microscopy techniques, (2) electronic particle counting which detects and counts cells by sensing a change in the electrical conductivity of a channel separating two electrolyte solutions when blood cells flow through this channel, and (3) the electro-o...

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Platelets in Animals

Cited by 13 publications

References 0 publications

Transport of Taurine by Normal Human Blood Platelets

Transport of Taurine by Normal Human Blood Platelets

Microfilaments in Cellular and Developmental Processes

Evaluation of an automatic platelet counting system utilizing whole blood

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