Normal Platelet Function In Scurvy And Experimental Human Vitamin C Deficiency

1981 ◽  
Author(s):  
G J Johnson ◽  
D Holloway ◽  
S Hutton ◽  
W Duane
Keyword(s):  
Platelet Function ◽  
Control Period ◽  
Hemorrhagic Diathesis ◽  
Platelet Dysfunction ◽  
Normal Range ◽  
Deficient Diet ◽  
Healthy Human ◽  
Normal Platelet

Mucocutaneous hemorrhage is a prominent feature of human scurvy. Platelet dysfunction has been observed in scorbutic guinea pigs and some humans with scurvy, but others have found normal platelet function in human scurvy. Since it is uncertain whether platelet dysfunction contributes to the hemorrhagic diathesis of scurvy, we studied platelet function in one patient with typical perifollicular hemorrhagic manifestations of scurvy and in five healthy human ascorbic acid (AA) deficient volunteers. Volunteers were hospitalized on a metabolic ward, and fed a diet providing 3-4mg AA per day. Platelet function studies were performed at the end of a) a 30 day control period of AA supplementation; b) a 60 day period of AA deficiency; and c) a 40 day period of AA supplementation. The patient with scurvy was studied before and 10 days after AA supplementation. The following platelet studies were performed: venous count, bleeding time (Ivy method), in vitro adhesiveness (Bowie method), in vivo adhesiveness (Johnson method), aggregation in response to ADP, collagen, epinephrine, sodium arachidonate and ristocetin, and 14C-serotonin release. Plasma and leukocyte AA were found to be normal in both periods of supplementation and markedly decreased (plasma mean 0.12 ± 0.02mg/dl; WBC mean 8.9 ± 1.8μg/108 cells) following the deficient diet. Plasma AA was 0.07mg/dl and WBC AA was 4.92μg/108 cells in the scurvy patient. Platelet count and all platelet function studies were within the normal range in the patient with scurvy and all volunteers during AA supplementation. In vivo platelet adhesiveness decreased in 4 of the 5 volunteers during AA deficiency, but it remained in the normal range in all but one. All other studies were normal in both AA deficient volunteers and the patient with scurvy. We conclude that significant platelet dysfunction does not accompany subclinical AA deficiency, and that platelet dysfunction is not primarily responsible for the hemorrhagic diathesis of scurvv.

scholarly journals Superoxide Dismutase 2 is dispensable for platelet function

2017 ◽  
Vol 117 (10) ◽  
pp. 1859-1867 ◽  
Author(s):  
Trevor P. Fidler ◽  
Jesse W. Rowley ◽  
Claudia Araujo ◽  
Luc H. Boudreau ◽  
Alex Marti ◽  
...  
Keyword(s):  
Superoxide Dismutase ◽  
Platelet Activation ◽  
Platelet Function ◽  
Mitochondrial Function ◽  
Oxygen Species ◽  
Platelet Dysfunction ◽  
Mitochondrial Ros ◽  
Superoxide Dismutase 2

SummaryIncreased intracellular reactive oxygen species (ROS) promote platelet activation. The sources of platelet-derived ROS are diverse and whether or not mitochondrial derived ROS, modulates platelet function is incompletely understood. Studies of platelets from patients with sickle cell disease, and diabetes suggest a correlation between mitochondrial ROS and platelet dysfunction. Therefore, we generated mice with a platelet specific knockout of superoxide dismutase 2 (SOD2-KO) to determine if increased mitochondrial ROS increases platelet activation. SOD2-KO platelets demonstrated decreased SOD2 activity and increased mitochondrial ROS, however total platelet ROS was unchanged. Mitochondrial function and content were maintained in non-stimulated platelets. However SOD2-KO platelets demonstrated decreased mitochondrial function following thrombin stimulation. In vitro platelet activation and spreading was normal and in vivo, deletion of SOD2 did not change tail-bleeding or arterial thrombosis indices. In pathophysiological models mediated by platelet-dependent immune mechanisms such as sepsis and autoimmune inflammatory arthritis, SOD2-KO mice were phenotypically identical to wildtype controls. These data demonstrate that increased mitochondrial ROS does not result in platelet dysfunction.

scholarly journals The secreted tyrosine kinase VLK is essential for normal platelet activation and thrombus formation

2021 ◽  
Author(s):  
Leila Revollo ◽  
Glenn Merrill-Skoloff ◽  
Karen De Ceunynck ◽  
James R. Dilks ◽  
Mattia Bordoli ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Phosphorylation ◽  
Platelet Activation ◽  
Platelet Function ◽  
Secretory Pathway ◽  
Thrombus Formation ◽  
Extracellular Proteins ◽  
Normal Platelet

AbstractTyrosine phosphorylation of extracellular proteins is observed in cell cultures and in vivo, but little is known about the functional roles of tyrosine phosphorylation of extracellular proteins. Vertebrate Lonesome Kinase (VLK) is a broadly expressed secretory pathway tyrosine kinase present in platelet ɑ-granules. It is released from platelets upon activation and phosphorylates substrates extracellularly. Its role in platelet function, however, has not been previously studied. In human platelets, we identified phosphorylated tyrosines mapped to luminal or extracellular domains of transmembrane and secreted proteins implicated in the regulation of platelet activation. To determine the role of VLK in extracellular tyrosine phosphorylation and platelet function, we generated mice with a megakaryocyte/platelet-specific deficiency of VLK. Platelets from these mice are normal in abundance and morphology, but have dramatic changes in function both in vitro and in vivo. Resting and thrombin-stimulated VLK-deficient platelets demonstrate a significant decrease of several tyrosine phosphobands. Functional testing of VLK-deficient platelets shows decreased PAR4- and collagen-mediated platelet aggregation, but normal responses to ADP. Dense granule and α-granule release are reduced in these platelets. Furthermore, VLK-deficient platelets exhibit decreased PAR4-mediated Akt (S473) and Erk1/2(T202/Y204) phosphorylation, indicating altered proximal signaling. In vivo, mice lacking VLK in megakaryocytes/platelets demonstrate strongly reduced platelet accumulation and fibrin formation following laser-injury of cremaster arterioles compared to controls. These studies demonstrate that the secretory pathway tyrosine kinase VLK is critical for stimulus-dependent platelet activation and thrombus formation, providing the first evidence that a secreted protein kinase is required for normal platelet function.

scholarly journals The secreted tyrosine kinase VLK is essential for normal platelet activation and thrombus formation

Blood ◽  
2021 ◽  
Author(s):  
Leila Denise Revollo ◽  
Glenn Merrill-Skoloff ◽  
Karen De Ceunynck ◽  
James R Dilks ◽  
Shihui Guo ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Phosphorylation ◽  
Platelet Activation ◽  
Platelet Function ◽  
Secretory Pathway ◽  
Thrombus Formation ◽  
Extracellular Proteins ◽  
Normal Platelet

Tyrosine phosphorylation of extracellular proteins is observed in cell cultures and in vivo, but little is known about the functional roles of tyrosine phosphorylation of extracellular proteins. Vertebrate Lonesome Kinase (VLK) is a broadly expressed secretory pathway tyrosine kinase present in platelet ɑ-granules. It is released from platelets upon activation and phosphorylates substrates extracellularly. Its role in platelet function, however, has not been previously studied. In human platelets, we identified phosphorylated tyrosines mapped to luminal or extracellular domains of transmembrane and secreted proteins implicated in the regulation of platelet activation. To determine the role of VLK in extracellular tyrosine phosphorylation and platelet function, we generated mice with a megakaryocyte/platelet-specific deficiency of VLK. Platelets from these mice are normal in abundance and morphology, but have significant changes in function both in vitro and in vivo. Resting and thrombin-stimulated VLK-deficient platelets demonstrate a significant decrease of several tyrosine phosphobands. Functional testing of VLK-deficient platelets shows decreased PAR4- and collagen-mediated platelet aggregation, but normal responses to ADP. Dense granule and a-granule release are reduced in these platelets. Furthermore, VLK-deficient platelets exhibit decreased PAR4-mediated Akt (S473) and Erk1/2 (T202/Y204) phosphorylation, indicating altered proximal signaling. In vivo, mice lacking VLK in megakaryocytes/platelets demonstrate strongly reduced platelet accumulation and fibrin formation following laser-injury of cremaster arterioles compared to controls, but normal bleeding times. These studies demonstrate that the secretory pathway tyrosine kinase VLK is critical for stimulus-dependent platelet activation and thrombus formation, providing the first evidence that a secreted protein kinase is required for normal platelet function.

Bleeding in Uremic Patients after Carbenicillin

1976 ◽  
Vol 36 (01) ◽  
pp. 115-126 ◽  
Author(s):  
K Andrassy ◽  
E Weischedel ◽  
E Ritz ◽  
T Andrassy
Keyword(s):  
Platelet Function ◽  
Antithrombin Iii ◽  
Serum Levels ◽  
Coagulation Factors ◽  
Coagulation System ◽  
Hemorrhagic Diathesis ◽  
Thrombin Time ◽  
Antithrombin Iii Activity

SummaryHemorrhagic diathesis was observed in patients with renal insufficiency after carbenicillin at serum levels > 300 μg/ml. Normal coagulation factors (F. I, II, V, VII, VIII, X), normal PTT, normal platelet counts, negative ethanol gelation test (fibrin monomers) were found as well as a prolongation of thromboplastin time (Quick), thrombin time, reptilase time and thrombin coagulase time. Platelet function was disturbed. In addition, the plasmatic system was involved: inhibition of fibrinogen-fibrin conversion (Belitser assay) and enhanced antithrombin III activity; in vivo the latter was ascribed to a heparin-like activity. In vitro, abnormal fibrinogen-fibrin conversion and a modified electrophoretic mobility of antithrombin III was seen: however an enhanced antithrombin III activity in vitro was not found with carbenicillin and various penicillin derivatives.This study demonstrates that carbenicillin, in addition to its known effect on platelet function, also disturbs the plasmatic coagulation system. This additional effect of carbenicillin is clinically important since protamin chloride effectively blocks bleeding without interfering with antibacterial activity.Both penicillin and penicillin derivatives have been shown to interfere with hemostasis and to cause clinically manifest hemorrhagic diathesis (Fleming and Fish 1947, Lurie et al. 1970a, b, McClure et al. 1970, Yudis et al. 1972, Demos 1971, Waisbren et al. 1971). Carbenicillin interferes with ADP-, collagen- or thrombin-induced platelet aggregation and with the release reaction both in vivo (McClure et al. 1970, Cazenave et al. 1973) and in vitro (McClure et al. 1970, Cazenave et al. 1973). In addition Lurie and colleagues (1970b) concluded that an inhibition of the conversion of fibrinogen to fibrin is involved although no experimental details were given. Later Brown and colleagues (1974) concluded that carbenicillin at usual dose levels “only affects the platelet component of hemostasis and has little effect on fibrin formation or other phases of coagulation in patients with normal renal function”.

scholarly journals Beta-lactam antibiotic-induced platelet dysfunction: evidence for irreversible inhibition of platelet activation in vitro and in vivo after prolonged exposure to penicillin

Blood ◽  
1990 ◽  
Vol 75 (7) ◽  
pp. 1473-1480 ◽  
Author(s):  
SF Burroughs ◽  
GJ Johnson
Keyword(s):  
Antibiotic Treatment ◽  
Platelet Function ◽  
Prolonged Exposure ◽  
Ex Vivo ◽  
Beta Lactam ◽  
Platelet Dysfunction ◽  
Irreversible Inhibition ◽  
Beta Lactam Antibiotics

beta-Lactam antibiotics cause platelet dysfunction with bleeding complications. Previous in vitro studies documented reversible inhibition of agonist-receptor interaction. This mechanism is inadequate to explain the effect of beta-lactam antibiotics in vivo. Platelet function does not return to normal immediately after drug treatment, implying irreversible inhibition of platelet function. We report here evidence of irreversible platelet functional and biochemical abnormalities after in vitro and in vivo exposure to beta-lactam antibiotics. Irreversible binding of [14C]-penicillin (Pen) occurred in vitro. After 24 hours' in vitro incubation with 10 to 20 mmol/L Pen, or ex vivo after antibiotic treatment, irreversible functional impairment occurred; but no irreversible inhibition of alpha 2 adrenergic receptors, measured with [3H]-yohimbine, or high-affinity thromboxane A2/prostaglandin H2 (TXA2/PGH2) receptors, measured with agonist [3H]-U46619 and antagonist [3H]-SQ29548, occurred. However, low- affinity platelet TXA2/PGH2 receptors were decreased 40% after Pen exposure in vitro or in vivo, indicating irreversible membrane alteration. Two postreceptor biochemical events were irreversibly inhibited in platelets incubated with Pen for 24 hours in vitro or ex vivo after antibiotic treatment. Thromboxane synthesis was inhibited 28.3% to 81.7%. Agonist-induced rises in cytosolic calcium ([Ca2+]i) were inhibited 40.1% to 67.5% in vitro and 26.6% to 52.2% ex vivo. Therefore, Pen binds to platelets after prolonged exposure, resulting in irreversible dysfunction attributable to inhibition of TXA2 synthesis and impairment of the rise in [Ca2+]i. The loss of low- affinity TXA2/PGH2 receptors suggests that the primary site of action of these drugs is on the platelet membrane.

scholarly journals Beta-lactam antibiotic-induced platelet dysfunction: evidence for irreversible inhibition of platelet activation in vitro and in vivo after prolonged exposure to penicillin

Blood ◽  
1990 ◽  
Vol 75 (7) ◽  
pp. 1473-1480 ◽  
Author(s):  
SF Burroughs ◽  
GJ Johnson
Keyword(s):  
Antibiotic Treatment ◽  
Platelet Function ◽  
Prolonged Exposure ◽  
Ex Vivo ◽  
Beta Lactam ◽  
Platelet Dysfunction ◽  
Irreversible Inhibition ◽  
Beta Lactam Antibiotics

Abstract beta-Lactam antibiotics cause platelet dysfunction with bleeding complications. Previous in vitro studies documented reversible inhibition of agonist-receptor interaction. This mechanism is inadequate to explain the effect of beta-lactam antibiotics in vivo. Platelet function does not return to normal immediately after drug treatment, implying irreversible inhibition of platelet function. We report here evidence of irreversible platelet functional and biochemical abnormalities after in vitro and in vivo exposure to beta-lactam antibiotics. Irreversible binding of [14C]-penicillin (Pen) occurred in vitro. After 24 hours' in vitro incubation with 10 to 20 mmol/L Pen, or ex vivo after antibiotic treatment, irreversible functional impairment occurred; but no irreversible inhibition of alpha 2 adrenergic receptors, measured with [3H]-yohimbine, or high-affinity thromboxane A2/prostaglandin H2 (TXA2/PGH2) receptors, measured with agonist [3H]-U46619 and antagonist [3H]-SQ29548, occurred. However, low- affinity platelet TXA2/PGH2 receptors were decreased 40% after Pen exposure in vitro or in vivo, indicating irreversible membrane alteration. Two postreceptor biochemical events were irreversibly inhibited in platelets incubated with Pen for 24 hours in vitro or ex vivo after antibiotic treatment. Thromboxane synthesis was inhibited 28.3% to 81.7%. Agonist-induced rises in cytosolic calcium ([Ca2+]i) were inhibited 40.1% to 67.5% in vitro and 26.6% to 52.2% ex vivo. Therefore, Pen binds to platelets after prolonged exposure, resulting in irreversible dysfunction attributable to inhibition of TXA2 synthesis and impairment of the rise in [Ca2+]i. The loss of low- affinity TXA2/PGH2 receptors suggests that the primary site of action of these drugs is on the platelet membrane.

A Comparison of the Effect of Decorsin and Two Disintegrins, Albolabrin and Eristostatin, on Platelet Function

1995 ◽  
Vol 74 (05) ◽  
pp. 1316-1322 ◽  
Author(s):  
Mary Ann McLane ◽  
Jagadeesh Gabbeta ◽  
A Koneti Rao ◽  
Lucia Beviglia ◽  
Robert A Lazarus ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Platelet Function ◽  
Sequence Similarity ◽  
Platelet Aggregation Inhibitors ◽  
Antiplatelet Drug ◽  
Rgd Sequence ◽  
Fibrinogen Receptor ◽  
Activated Platelets

SummaryNaturally-occurring fibrinogen receptor antagonists and platelet aggregation inhibitors that are found in snake venom (disintegrins) and leeches share many common features, including an RGD sequence, high cysteine content, and low molecular weight. There are, however, significant selectivity and potency differences. We compared the effect of three proteins on platelet function: albolabrin, a 7.5 kDa disintegrin, eristostatin, a 5.4 kDa disintegrin in which part of the disintegrin domain is deleted, and decorsin, a 4.5 kDa non-disintegrin derived from the leech Macrobdella decora, which has very little sequence similarity with either disintegrin. Decorsin was about two times less potent than albolabrin and six times less potent than eristostatin in inhibiting ADP- induced human platelet aggregation. It had a different pattern of interaction with glycoprotein IIb/IIIa as compared to the two disintegrins. Decorsin bound with a low affinity to resting platelets (409 nM) and to ADP-activated platelets (270 nM), and with high affinity to thrombin- activated platelets (74 nM). At concentrations up to 685 nM, it did not cause expression of a ligand-induced binding site epitope on the (β3 subunit of the GPIIb/IIIa complex. It did not significantly inhibit isolated GPIIb/IIIa binding to immobilized von Willebrand Factor. At low doses (1.5-3.0 μg/mouse), decorsin protected mice against death from pulmonary thromboembolism, showing an effect similar to eristostatin. This suggested that decorsin is a much more potent inhibitor of platelet aggregation in vivo than in vitro, and it may have potential as an antiplatelet drug.

Superoxide, Xanthine Oxidase and Platelet Reactions: Further Studies on Mechanisms by which Oxidants Influence Platelets

1981 ◽  
Vol 45 (03) ◽  
pp. 290-293 ◽  
Author(s):  
Peter H Levine ◽  
Danielle G Sladdin ◽  
Norman I Krinsky
Keyword(s):  
Superoxide Dismutase ◽  
Cytochrome C ◽  
Xanthine Oxidase ◽  
Direct Effect ◽  
Platelet Function ◽  
Experimental Conditions ◽  
Release Reaction

SummaryIn the course of studying the effects on platelets of the oxidant species superoxide (O- 2), Of was generated by the interaction of xanthine oxidase plus xanthine. Surprisingly, gel-filtered platelets, when exposed to xanthine oxidase in the absence of xanthine substrate, were found to generate superoxide (O- 2), as determined by the reduction of added cytochrome c and by the inhibition of this reduction in the presence of superoxide dismutase.In addition to generating Of, the xanthine oxidase-treated platelets display both aggregation and evidence of the release reaction. This xanthine oxidase induced aggreagtion is not inhibited by the addition of either superoxide dismutase or cytochrome c, suggesting that it is due to either a further metabolite of O- 2, or that O- 2 itself exerts no important direct effect on platelet function under these experimental conditions. The ability of Of to modulate platelet reactions in vivo or in vitro remains in doubt, and xanthine oxidase is an unsuitable source of O- 2 in platelet studies because of its own effects on platelets.

The Effect of Barbituric Acid Derivatives on Platelet Function in Vitro and in Vivo

1973 ◽  
Vol 30 (02) ◽  
pp. 315-326
Author(s):  
J. Heinz Joist ◽  
Jean-Pierre Cazenave ◽  
J. Fraser Mustard
Keyword(s):  
Platelet Aggregation ◽  
Platelet Function ◽  
Barbituric Acid ◽  
Platelet Rich Plasma ◽  
Inhibitory Effect ◽  
Primary Response ◽  
Sodium Pentobarbital ◽  
Barbituric Acid Derivatives

SummarySodium pentobarbital (SPB) and three other barbituric acid derivatives were found to inhibit platelet function in vitro. SPB had no effect on the primary response to ADP of platelets in platelet-rich plasma (PRP) or washed platelets but inhibited secondary aggregation induced by ADP in human PRP. The drug inhibited both phases of aggregation induced by epinephrine. SPB suppressed aggregation and the release reaction induced by collagen or low concentrations of thrombin, and platelet adherence to collagen-coated glass tubes. The inhibition by SPB of platelet aggregation was readily reversible and isotopically labeled SPB did not become firmly bound to platelets. No inhibitory effect on platelet aggregation induced by ADP, collagen, or thrombin could be detected in PRP obtained from rabbits after induction of SPB-anesthesia.

Human Platelet Acetylcholinesterase: The Effects of Anticholinesterases on Platelet Function

1979 ◽  
Vol 42 (05) ◽  
pp. 1615-1619 ◽  
Author(s):  
Martin J Smith ◽  
Boyd Braem ◽  
Kent D Davis
Keyword(s):  
Platelet Function ◽  
Ache Activity ◽  
Room Temperature ◽  
Platelet Rich Plasma ◽  
Complete Inhibition ◽  
Clot Retraction ◽  
Plasma Clot ◽  
Normal Platelet ◽  
Aggregation Factor

SummaryPlatelet acetylcholinesterase (AChE) activity was measured in gel-filtered platelet preparations. Three different anticholinesteratic agents (eserine, neostigmine, and diiso- propylphosphorofluoridate) at final concentrations of 10 μM caused complete inhibition of AChE activity after 30 min incubation at room temperature with either platelet-rich plasma or gel-filtered platelets. Complete inhibition of platelet AChE had no effect on platelet aggregation, factor-3 availability, and plasma clot retraction. We conclude that platelet membrane AChE activity is not required for normal platelet function as measured by these in vitro parameters.

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