Bovine Platelet Antiheparin Protein: Platelet Factor 4*

Ciaglowski, Raymond E.; Snow, June; Walz, Daniel A.

doi:10.1111/j.1749-6632.1981.tb29774.x

Cited by 17 publications

(3 citation statements)

References 21 publications

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“…A high degree of sequence homology between bovine and human PF4 has been reported. 10,11,22 This seems to suggest that the PF4 molecule is fairly consistent in structure among many animal species, thus permitting the use of nonhuman sources of the protein for experimental manipulations and extrapolation of data back to human conditions.…”

Section: Inhibition Of Collagenase Activitymentioning

confidence: 95%

“…10,64 It is the extra amino acids that make the bovine molecule more soluble than human PF4. 10,11 During platelet aggregation, PF4 is released as a complex of two tetramers of PF4 and two molecules of its proteoglycan carrier. 43 Human PF4 is poorly soluble when the protein molecule is dissociated from its proteoglycan carrier.…”

Section: The Purification and Characterization Of Pf4mentioning

confidence: 99%

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In Vivo Studies on the Binding of Heparin and Its Fractions with Platelet Factor 4

Walz¹,

Hung²

1985

Semin Thromb Hemost

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PF4 has a half-life in plasma of less than 3 minutes, and its rapid clearance appears to be a function of binding to the vascular endothelium. Once bound to the endothelium, PF4 can be released by heparin in a time-dependent manner; recovery is greater the sooner heparin is administered following PF4 infusion. This heparin-induced release of PF4 can be abolished if the heparin is first complexed with hexadimethrine bromide. Likewise, this heparin-induced release of PF4 is dependent upon the type of heparin used; low molecular weight heparin fractions and fragments do not cause the PF4 rebound seen with intact heparin. Thus, it would appear that low molecular weight forms of heparin are advantageous in that their in vivo administration would not be mediated by such platelet modulators as PF4.

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Section: Inhibition Of Collagenase Activitymentioning

confidence: 95%

Section: The Purification and Characterization Of Pf4mentioning

confidence: 99%

In Vivo Studies on the Binding of Heparin and Its Fractions with Platelet Factor 4

Walz¹,

Hung²

1985

Semin Thromb Hemost

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“…Sequence studies of human PF4 23,31,46,75,109,115 indicated a single protein chain having 70 amino acids and with a subunit molecular weight of 7780 daltons. The sequence of human BTG 8 is an 81 residue protein (85 for LA-PF4).…”

Section: The Characterization Of Pf4mentioning

confidence: 99%

Platelet-Released Proteins as Molecular Markers for the Activation Process

Walz¹

1984

Semin Thromb Hemost

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The desire to have a specific, sensitive marker for platelet activation was originally thought to lie in the development of RIAs for BTG and PF4. Although this wish has not been denied, the interpretation of the information obtained from such an analysis has proved far less rewarding. The principal challenge of these procedures is based upon the lack of a cause and effect relationship between a given disease and platelet activation, coupled with the differential clearance rate and mechanism for each of the discussed proteins. Thus, we have seen that the renal clearance rate and mechanism for each of the discussed proteins. Thus, we have seen that the renal clearance of a patient should be noted prior to interpreting the elevation of BTG. Similarly, since PF4 is removed from the circulation so rapidly, its plasma values tend to be lower than BTG by a factor of 5, although the significance of the BTG to PF4 ratio is questioned. Administration of heparin results in a heparin-induced increase in plasma PF4 levels but not for BTG, and this PF4 increase can be as great as 20-fold. PF4 and BTG values are also directly increased by pressure increases. Taken individually, these mediators each compromise the ability to correlate the significance of platelet protein increases with any single pathologic condition. When viewed collectively, an analysis of platelet-released proteins is best interpreted as an indication that the functional integrity of the platelet has been perturbed; the direct relationship of disease processes to platelet release is far from certain and is simply documented by the use of such described procedures. The final note of caution for these assays is to be found in the recent summary analysis of the standardization of both BTG and PF4. In this study, considerably greater variation among laboratories was noted for PF4 than was seen for BTG, and the study directors concluded that comparisons of results between laboratories should be regarded as unreliable due mainly to the use of different standards for each protein in a given laboratory. The final note of caution for these assays is to be found in the recent summary analysis of the standardization of both BTG and PF4. In this study, considerably greater variation among laboratories was noted for PF4 than was seen for BTG, and the study directors concluded that comparisons of results between laboratories should be regarded as unreliable due mainly to the use of different standards for each protein in a given laboratory.

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Radioimmunoassay of Platelet Proteins

Pepper¹

1987

Radioimmunoassay in Basic and Clinical Pharmacology

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Bovine Platelet Antiheparin Protein: Platelet Factor 4*

Cited by 17 publications

References 21 publications

In Vivo Studies on the Binding of Heparin and Its Fractions with Platelet Factor 4

In Vivo Studies on the Binding of Heparin and Its Fractions with Platelet Factor 4

Platelet-Released Proteins as Molecular Markers for the Activation Process

Radioimmunoassay of Platelet Proteins

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