© 1995 American Heart Association, Inc.
Articles |
Thrombotic Thrombocytopenia Induced in Dogs and Pigs
The Role of Plasma and Platelet vWF in Animal Models of Thrombotic Thrombocytopenic Purpura
From the Department of Pathology, School of Medicine, University of North Carolina, Chapel Hill.
Correspondence to William E. Sanders, Jr, MD, Division of Cardiology, CB #7075, Burnett-Womack Bldg, University of North Carolina Hospitals, Chapel Hill, NC 27599-7075.
 |
Abstract |
|---|
 Top Abstract IntroductionMethodsResultsDiscussionReferences |
|---|
Abstract Thrombotic thrombocytopenia with severe depletion of plasma von Willebrand factor (vWF) was induced in normal large animals (5 dogs and 2 pigs) by botrocetin, a Bothrops factor requiring vWF for platelet agglutination. Botrocetin (90 to 100 U/kg, 2.14 to 2.38 mg/kg, in a single IV injection) reduced plasma vWF activity to <0.1 U/mL for 24 hours. During this period, multimeric analysis of plasma vWF antigen (Ag) revealed the loss of intermediate- and high-molecular-weight forms with a concomitant increase in lower molecular weight forms. A moderate reduction in factor VIII (FVIII) activity was observed. The vWF reduction was accompanied by transient thrombocytopenia and prolonged bleeding times during the deficiency state. Occlusive platelet thrombi were detected by transmission electron microscopy in the microcirculation of lung and spleen but not kidney or brain 30 minutes after the botrocetin injection. Recovery of plasma vWF and platelet count occurred within 48 hours and was associated with the appearance in the plasma of unusually large forms of vWF:Ag multimers. The vWF:Ag multimer distribution was normal at 72 hours. The ultrastructural distribution of vWF in unstimulated normal porcine and canine platelets was examined by using immunogold staining. VWF was detected in the
-granules of normal pig
platelets but was not observed in platelets from normal dogs. However,
both animals developed thrombotic thrombocytopenia when injected with
botrocetin. A second group of animals (2 dogs and 3 pigs) with von
Willebrand disease (vWD) was given a single botrocetin injection (90 to
100 U/kg). No thrombocytopenia occurred. Electron photomicrographs
showed no platelet thrombi in any tissues examined. Porcine and canine
platelets from vWD animals exhibited no specific labeling of vWF in any
-granule. The vWD animals were entirely protected from the
thrombocytopenia and thrombogenic action of botrocetin. These data
suggest that plasma vWF but not platelet vWF is required for the
intravascular platelet and microthrombotic response and that the
thrombotic thrombocytopenic syndrome cannot be induced in the absence
of plasma vWF.
Key Words: thrombotic thrombocytopenia • thrombotic thrombocytopenic purpura • von Willebrand disease • von Willebrand factor
|
Introduction |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
Thrombotic thrombocytopenic purpura (TTP) was first recognized by Moschcowitz.1 The disorder is characterized by pronounced thrombocytopenia, microangiopathic hemolytic anemia, fluctuating mental status, mild renal dysfunction, and fever. The pathological lesions in TTP consist of widely disseminated platelet thrombi with prominent concentrations within the microcirculation of the myocardium, pancreas, adrenals, kidney, brain, and lung.2 In acute TTP and chronic TTP in remission, qualitative and quantitative abnormalities of plasma von Willebrand factor (vWF) have been described.3 4 5 During acute episodes of recurrent TTP, all but the lowest molecular weight forms of vWF antigen (Ag) disappear from the plasma.4 6 7 Similar pathological findings and plasma vWF:Ag changes have been reported in hemolytic uremic syndrome (HUS).8 These studies suggest that vWF may play a significant role in the pathogenesis of TTP and HUS.
A unique factor contained in certain snake venoms, predominantly those of the Bothrops species, initiates platelet agglutination only in the presence of vWF.9 This Bothrops factor, referred to as botrocetin, can be used as a probe for plasma vWF.9 10 11 12 The intravenous injection of botrocetin into normal rats induces acute thrombocytopenia, loss of higher molecular weight forms of vWF:Ag in the plasma, and the concomitant appearance of intravascular platelet microthrombi.13 The pathophysiological findings observed in this animal model resemble those occurring in TTP and, to a lesser extent, HUS.
The compartmental localization of vWF, ie, endothelium-plasma versus megakaryocyte-platelet, is species or strain dependent.14 15 16 With normal pigs and dogs, this difference permits the assessment of the relative contribution of plasma and platelet vWF to the induction of thrombotic thrombocytopenia. Our study was designed to produce and further characterize the thrombotic thrombocytopenic state by administration of botrocetin to large animals (normal pigs and dogs).17 The response of animals with von Willebrand disease (vWD) to botrocetin infusion was also evaluated. A preliminary report of some of the data is available.12
|
Methods |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
Experimental Animals
Phenotypically normal and homozygous vWD dogs and pigs of both sexes were used.17 18 The dogs, aged 4 to 8 months, weighed 13 to 16 kg; the pigs, aged 1 to 4 months, weighed 9 to 20 kg. The animals came from controlled breedings of stock maintained at the Francis Owen Blood Research Laboratory, University of North Carolina at Chapel Hill. The standards in "Guide for the Care and Use of Laboratory Animals" (National Institutes of Health publication 85-23) were followed.
Preparation of Botrocetin
Botrocetin for the infusion experiments was prepared from crude
dried venom of Bothrops jararaca (Sigma) by chromatography
on a diethylaminoethyl-cellulose column.9 One unit of
botrocetin is defined as that amount in 1 mL that causes a platelet
agglutination time of 14 seconds in a standard four-part test
system.17 One unit of botrocetin weighs approximately 23.8
µg protein/mL.19 Botrocetin fractions were made
approximately isotonic (equivalent to 0.154 mol/L NaCl) by dilution or
dialysis and were further diluted with saline containing canine or
porcine albumin (0.1%) (Sigma) for dog and pig experiments,
respectively. The final botrocetin preparations had no detectable
thrombin-like activity.
Botrocetin Infusion Studies
The dose of botrocetin required to produce significant
thrombocytopenia (<25% of preinjection level) in normal pigs and dogs
was determined by a series of graded dose infusions (range, 30 to 100
U/kg, 0.71 to 2.38 mg/kg). The general procedure for infusions has been
described.17 A single botrocetin dose (90 to 100 U/kg IV)
was injected into the cephalic vein of the pig (2 normal and 3 vWD) and
the jugular vein of the dog (5 normal and 2 vWD) at the rate of 1 to 4
mL/min. Blood samples were drawn into 3.2% sodium citrate in the ratio
of nine parts blood to one part anticoagulant. Platelet-poor citrated
plasmas were prepared and stored at -20°C until tested. Samples for
analysis were obtained from each animal on separate days prior to
infusion, immediately before infusion, and at 20 minutes and 1, 2, 4,
8, 12, 24, 48, and 72 hours after infusion. A 96- or 120-hour sample
was also drawn in a subset of animals.
Assays for vWF and Factor VIII Activity
VWF activity was assayed by using a macroscopic agglutination
test procedure.10 The test mixture contained equal parts
of the following: 0.084 mol/L imidazole-buffered saline, pH 7.35;
citrated dog or pig plasma, serially diluted with buffer; botrocetin 10
U/mL; and rehydrated dog platelets, paraformaldehyde-fixed and
lyophilized, 8x105/L17. FVIII assays
were performed by a modification of the partial thromboplastin time
procedure20 by using canine hemophilia plasma substrate.
The nonactivated partial thromboplastin time was used to assay porcine
plasma FVIII, and the kaolin-activated procedure was used to assay
canine plasma FVIII. VWF and FVIII values are expressed as a percentage
for comparison to a normal reference dog or pig plasma pool (4 or 5
animals) that was assigned a value of 100%.
Determination and Characterization of vWF:Ag and vWF:Ag
Multimers
A modified Laurell method was used to determine
vWF:Ag.21 22 Multimeric distribution of vWF:Ag was
analyzed by the modification of Aihara et al23 of the
Ruggeri-Zimmerman24 procedure using 1.5% agarose gels.
The primary antibody was rabbit anti-dog vWF.16 Antisera
were made vWF specific by absorption with cryoprecipitate prepared from
canine vWD plasma. Laser densitometry was performed on dry sodium
dodecyl sulfate gels23 by using the LKB Ultrascan XL. The
area under the curve corresponding to the multimeric group was
determined by planimetry.
Platelet Counts and Bleeding Times
The Unopette microcollection system (No. 5855, Becton-Dickinson)
was employed to determine platelet concentrations. Saline bleeding
times were performed by the Mertz method25 at the time of
blood sampling.
Evaluation of In Vivo Platelet Thrombi by Light and Electron
Microscopy
Two normal dogs and 1 vWD dog were euthanized with large doses
of sodium pentobarbital (120 mg/kg) 30 minutes after botrocetin
administration. Sections of lung, liver, spleen, kidney, myocardium,
and brain were obtained for light and transmission electron microscopy.
The tissues for light microscopy were fixed in 10% buffered formalin.
Sections were stained with hematoxylin and eosin. Small (1- to 2-mm)
pieces of tissue for transmission electron microscopy were fixed in 4%
phosphate-buffered paraformaldehyde. The fixed specimens were rinsed in
phosphate buffer and were then postfixed in 2% OsO4 for 1
hour. After osmium fixation, the samples were dehydrated through a
graded series of ethyl alcohols and further dehydrated with propylene
oxide and embedded in Epon. One-micron-thick sections were made from
each block; these were stained with toluidine blue and examined by
light microscopy to detect the presence of platelet microthrombi.
Appropriate areas were then selected for thin sections, stained with
uranyl acetate and lead citrate, and examined with a Zeiss 10A electron
microscope.26
Electron Microscopy and Immunolabeling for vWF
Platelets for immunoelectron microscopy were fixed in
phosphate-buffered paraformaldehyde (4%, pH 4). The platelets were
dehydrated through a graded series of ethanols and placed in
full-strength LR White resin overnight. The following day, the cells
were placed in fresh LR White resin in 00 gelatin capsules and
polymerized by using UV light. One-micron-thick sections were cut from
each block and stained with toluidine blue for orientation. Thin
sections from selected areas were cut by using a diamond knife and
placed on 200-mesh uncoated nickel grids. The thin sections were
stained according to the method described by Knibbs et
al27 to detect vWF. A rabbit antibody against human vWF
(Dako) that was previously shown to identify pig and dog
vWF16 was diluted 1:200 prior to use. The secondary
antibody, goat anti-rabbit immunoglobulin (Amersham), was conjugated to
gold beads (10 nm) and used at a 1:25 dilution.
|
Results |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
Induced Thrombotic Thrombocytopenia
Acute thrombotic thrombocytopenia with vWF deficiency was induced in normal large animals (5 dogs and 2 pigs) by a single injection of botrocetin (90 to 100 U/kg IV) to each animal (Table 1
).
The syndrome was more severe in the dogs than in the pigs given the
same dose of botrocetin, which suggests that pigs are partially
resistant to the effects of botrocetin injections.17
Microvascular platelet thrombi were demonstrated 30 minutes after
botrocetin injection (Fig 1).
|
|
An illustrative example of the response of platelets and vWF to
botrocetin administration in a normal dog is shown in Table 2. At the time that platelet microthrombi were observed
in this model, there was a severe thrombocytopenia (10 000/µL), a
reduced level of vWF activity (0.1 U/mL), and a partial loss of
high-molecular-weight multimers of vWF (estimated at 25%). The
bleeding time was prolonged, presumably because of the severe
thrombocytopenia, since 55% of the vWF activity remained. The vWF
activity remained severely depleted for 24 hours with recovery at 48
hours. FVIII levels fell to 45% of the preinjection value and returned
to normal in 72 hours. The thrombocytopenia was transient, with
recovery beginning at about 4 hours. During the period of severe
thrombocytopenia, blood samples revealed platelet aggregates (10 to 50
platelets per aggregate) in the hemacytometer by using phase contrast
microscopy. At 24 hours, the platelet count had risen to 240 000/µL
(>90% of the preinjection level). No hemorrhages were observed.
Bleeding time remained prolonged in all animals until platelet and vWF
recovery was complete at 48 hours. The vWF:Ag was analyzed by the
Laurell rocket procedure and Laemmli gel electrophoresis with laser
densitometry scans of the multimers (Fig 2). The vWF:Ag
(Laurell) increased initially and returned to baseline levels at 12
hours (data not shown). Loss of high- and intermediate-molecular-weight
multimers was seen in Laemmli electrophoresis gels. The
high-molecular-weight multimers were absent for 2 to 24 hours, and the
intermediate-molecular-weight multimers were absent or reduced for
4 to 24 hours. A concomitant increase in lower molecular weight forms
was noted.
|
|
A series of in vitro experiments was performed to demonstrate the removal of vWF from plasma by vWF-dependent platelet agglutination induced with botrocetin. Rehydrated lyophilized platelets were added to platelet-free plasma.28 The botrocetin-induced platelet agglutinates were removed by centrifugation. The plasma supernatant was assayed for vWF:Ag and vWF activity. Removal of vWF was dependent on both platelet and botrocetin concentrations. All the plasma vWF was removed by repeated additions of platelets and botrocetin. When no further vWF:Ag was present, platelet agglutination could no longer be induced by botrocetin (data not shown). VWF-specific fluorescent immunostaining of the platelet agglutinates was strongly positive.11
Botrocetin Injection of vWD Animals
Botrocetin induced no response when intravenously injected into
vWD animals (2 dogs and 3 pigs). No thrombocytopenia was observed
(Table 1
). VWF activity and vWF:Ag were undetectable in vWD dogs and
pigs. vWD animals appear to be protected from the action of
botrocetin.
Morphology of Platelet Microthrombi
Light microscopic examination of lung, spleen, liver,
kidney, myocardium, and brain sections 30 minutes after botrocetin
injection was performed in normal dogs. Platelet thrombi were detected
in the microcirculation of the lung (Fig 1) and spleen. Similar
microthrombi were not observed in the liver sinusoids, the capillaries
of the renal glomeruli, myocardium, or brain. No platelet microthrombi
were found in tissue sections of the vWD animal 30 minutes after
botrocetin injection (Fig 3).
|
Transmission electron photomicrographs of the lung 30 minutes after
botrocetin injection in normal dogs revealed occlusive platelet thrombi
in vessels of the pulmonary microcirculation (Fig 1). Photomicrographs
of the spleen 30 minutes after botrocetin administration demonstrated
large platelet thrombi consisting of tightly packed discrete platelets
(not shown).
Immunodetection of vWF in Platelets
Immunoelectron photomicrographs of normal porcine platelets show
vWF in the -granules (Fig 4). Gold particles were
localized either at one pole of the -granule or along the long axis,
corresponding to transverse or longitudinal sections of the granule.
The majority of -granules exhibited detectable vWF by immunogold
labeling. The absence of detectable vWF in certain -granules may
reflect the focal nature of distribution of vWF in these vesicles.
|
Normal canine platelet sections treated with canine-specific, anti-vWF
antibody followed by immunogold showed no specific labeling for vWF.
Occasional adherent gold particles were observed. However, the
concentration levels were no more than in the cytoplasm or other
organelles, and this type of labeling was indistinguishable from
background staining (Fig 4).
Platelets from vWD pigs and dogs were also examined for the presence of
vWF. No specific labeling of any -granule was observed in these
animals. An occasional gold particle was noted, but this labeling was
again indistinguishable from background staining.
|
Discussion |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
In the rat, botrocetin injection induces a thrombotic thrombocytopenia with vWF depletion that is similar in many respects to the pathophysiological changes observed in acute TTP and HUS.13 When infused into pigs (n=5) and dogs (n=4), botrocetin was found to cause a severe depletion of plasma vWF.17 The action of botrocetin is rapid and reversible in both pigs and dogs; however, normal pigs are more resistant to the effects of botrocetin than normal dogs. Botrocetin-induced agglutination of platelets is mediated through plasma vWF and the platelet receptor glycoprotein (GP) Ib.
At a botrocetin dose of 90 to 100 U/kg, normal animals experienced
acute severe thrombocytopenia (Table 1), plasma vWF depletion (Table 1), loss of middle- and high-molecular-weight forms of vWF:Ag (Table 2), prolonged bleeding times (Table 1), and platelet microthrombi in
the lung (Fig 1) and spleen. The bleeding time appears to become
prolonged in the botrocetin-induced syndrome only when the platelet
count is less than 10% of normal or when the vWF activity and the
high-molecular-weight multimers are depleted or nearly so (see Table 2,
lines 2 through 6). FVIII was reduced to approximately 50% of
preinjection values and began to recover after 24 hours. Platelet loss
and plasma vWF depletion persisted for 24 hours, after which recovery
of both was rapid and accompanied by the transient appearance of
very-high-molecular-weight vWF multimers. The microthrombi consist of
largely intact platelets and appear to consist of compacted platelet
agglutinates that may completely or partially occlude the
microvasculature (Fig 1). A total of 9 dogs and 7 pigs in this and
another study17 reacted in a similar stereotypical
manner.
Plasma vWF depletion can also be accomplished in vitro by adding botrocetin to platelet-free plasma that has been enriched with rehydrated lyophilized platelets. By repeating this procedure, all the vWF is removed.
In vWD animals, botrocetin produced no detectable response (Table 1). Transmission electron photomicrographs of the pulmonary
microvasculature 30 minutes after botrocetin injection showed no
platelet microthrombi (Fig 3). A deficiency of plasma vWF protected
against the action of botrocetin and prevented the induction of the
thrombotic thrombocytopenia syndrome in these animals.
There are many similarities in the development of and recovery from the thrombocytopenia induced by botrocetin and ristocetin. Based on in vivo studies in normal rats, dogs, and pigs in the case of botrocetin and in studies of normal rabbits and treated patients in the case of ristocetin, the severity of the thrombocytopenia is dose dependent, and the nadir in platelet count occurs within minutes of administration of the agent.13 17 29 With a single dose of either agent, there is a progressive recovery over 3 to 4 days. While ristocetin-induced thrombocytopenia may be accompanied by fibrinogenopenia, suggesting disseminated intravascular coagulation,29 botrocetin-induced thrombocytopenia is not. Botrocetin is a heterodimeric protein of 26 kD; ristocetin is a homodimeric glycopeptide of 2.3 kD. Both utilize the vWF-GPIb pathway. Their binding domains on the vWF molecule are located at separate30 but proximal sites on the 539 through 643 loop.31 Botrocetin binds to several discontinuous sequences of vWF within the A1 disulfide loop (amino acid 509 through 695).31 32 33 Ristocetin binds to similar surface sequences on both vWF and GPIb protein structures (X-Pro-Gly-X' at a b-turn in the protein motif).34 The pathogenesis of the thrombocytopenia with either agent involves a modification of the plasma vWF interacting with the platelet GPIb receptor, leading to formation of platelet aggregates.11 13 34 Botrocetin appears to function in a two-step manner by first binding with vWF to form a complex and then binding to GPIb to promote platelet agglutination and the thrombocytopenia.11 35 Ristocetin-induced thrombocytopenia could be due to a somewhat analogous sequence of events. However, no observations on microthrombosis following ristocetin infusion could be found.
Certain intravascular platelet reactions may depend on the
compartmental source and qualitative aspects of the vWF
molecule.15 16 Normal porcine platelets have been shown by
immunolabeling to contain vWF; however, vWF is not present in the
-granules of normal canine platelets or in platelets from vWD dogs
or pigs, as shown in this and other studies.14 16 36
Botrocetin injection produces thrombotic thrombocytopenia in normal
dogs as well as pigs, which suggests that plasma vWF is primarily
involved in the initiation of thrombotic thrombocytopenia in these
animals, and the absence or severe depletion of plasma vWF prevents or
modulates the induction of the syndrome.
The changes in the multimeric distribution of vWF:Ag observed in these
animal models of thrombotic thrombocytopenia closely approximate the
abnormalities reported in patients with acute TTP. The loss of plasma
vWF high-molecular-weight multimers is accompanied by an apparent
buildup of lower molecular weight forms (Table 2 and Fig 2). During
acute episodes of TTP and HUS, abnormalities of vWF:Ag multimers in the
plasma have been reported by using a porous sodium dodecyl sulfate 1%
to 1.3% agarose gel.3 5 6 In the initial acute phase of
TTP/HUS or with relapse of chronic TTP, all except the lowest molecular
weight vWF multimers disappear from the plasma.4 5 6 In one
TTP patient, cross-immunoelectrophoresis has demonstrated the
simultaneous appearance of smaller molecular weight multimers of vWF,
which are not normally present, and the disappearance of higher
molecular weight multimers from the plasma.5 This
depletion of high-molecular-weight forms of vWF:Ag temporally
corresponds to periods of severe thrombocytopenia and to the presence
of circulating agglutinated platelets.37 The return of
platelets and recovery of plasma vWF activity is thus associated with
the transient appearance of very-high-molecular-weight multimers (Table 2 and Fig 2). "Platelet aggregating/agglutinating factors" have
been proposed as the etiology of TTP/HUS.4 38 39
The pathogenesis of TTP and HUS remains unclear. Intravascular platelet agglutination and subsequent sequestration of these circulating platelet masses as microthrombi in various organs of patients with TTP was first proposed by Baehr et al in 1936.40 Many groups have reported platelet agglutinating factors in the plasma and serum of TTP patients.4 38 39 41 The characterization of these factors is an area of active investigation,5 38 42 43 44 45 but their origin remains obscure. Large vWF multimers, which are similar to the unusually large forms found in the plasma of patients with chronic TTP in remission, have been shown in vitro to support shear-induced platelet agglutination that does not require exogenous agents or desialation of vWF.46 This agglutination is ADP dependent and is the result of the binding of vWF to both the GPIb and GPIIb/IIIa complexes.47 Hence, circulating unusually large plasma vWF multimeric forms alone under certain conditions may be sufficient to induce in vivo platelet agglutination. Higher molecular weight forms of vWF are present in endothelial cells and platelets of humans and pigs.48 Qualitative differences exist in vWF that are dependent on compartmental source, including the ability to support thrombosis in injury models.16 Investigations focused on the qualitative aspects and source of vWF as well as the cofactors ("initiating agents") required for vWF-induced platelet microthrombi formation should help elucidate the mechanisms resulting in clinical TTP.
|
Acknowledgments |
|---|
This study was supported in part by grants HL-01648 and HL-26309 from the National Institutes of Health and by the George Silverburgh Fund for Thrombotic Thrombocytopenia Purpura Research. We thank Stephen Pemberton and Rebecca Simers for help in editing and preparing the manuscript and the staff of the Francis Owen Blood Research Laboratory for their technical assistance.
Received September 15, 1994; accepted March 21, 1995.
|
References |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
1. Moschcowitz E. An acute febrile peiochromic anemia with hyaline thrombosis of terminal arterioles and capillaries: an undescribed disease. Arch Intern Med. 1925;36:89-93.
2.
Berkowitz LR, Dalldorf FG, Blatt PM. Thrombotic
thrombocytopenic purpura: a pathology review. JAMA. 1979;241:1709-1710.
3. Moake JL, Rudy CK, Troll JH, Weinstein MJ, Colannino NM, Azocar J, Seder RH, Hong SL, Deykin D. Unusually large plasma factor VIII: von Willebrand factor multimers in chronic relapsing thrombotic thrombocytopenic purpura. N Engl J Med. 1982;307:1432-1435. [Medline] [Order article via Infotrieve]
4. Kelton JG, Moore J, Santos A, Sheridan D. Detection of a platelet-agglutinating factor in thrombotic thrombocytopenic purpura. Ann Intern Med. 1984;101:589-593.
5. Murphy WG, Moore JC, Barr RD, Pai MKR, Kelton JG. Relationship between platelet aggregating factor and von Willebrand factor in thrombotic thrombocytopenic purpura. Br J Haematol. 1987;66:509-513. [Medline] [Order article via Infotrieve]
6. Moake JL, McPherson PD. Abnormalities of von Willebrand factor multimers in thrombotic thrombocytopenic purpura and the hemolytic-uremic syndrome. Am J Med. 1989;87:3N-9N. [Medline] [Order article via Infotrieve]
7. Moake JL. New perspectives: recent observations on the pathophysiology of thrombotic thrombocytopenic purpura and the hemolytic-uremic syndrome. Hematol Pathol. 1990;4:197-201. [Medline] [Order article via Infotrieve]
8.
Moake JL, Byrnes JJ, Troll JH, Rudy CK, Weinstein MJ,
Colannino NM, Hong SL. Abnormal VIII: von Willebrand factor
patterns in the plasma of patients with the hemolytic-uremic
syndrome. Blood. 1984;64:592-598.
9.
Read MS, Shermer RW, Brinkhous KM. Venom
coagglutinin: an activator of platelet aggregation dependent on von
Willebrand factor. Proc Natl Acad Sci U S A. 1978;75:4514-4518.
10.
Brinkhous KM, Read MS. Use of venom coagglutinin
and lyophilized platelets in testing for platelet-aggregating von
Willebrand factor. Blood. 1980;55:517-520.
11.
Read MS, Smith SV, Lamb MA, Brinkhous KM.
Role of botrocetin in platelet agglutination: formation of an
activated complex of botrocetin and von Willebrand factor.
Blood. 1989;74:1031-1035.
12. Sanders WE, Brinkhous KM, Read MS. An animal model of thrombotic thrombocytopenia with von Willebrand factor deficiency: the role of botrocetin in studies of human TTP. In: Kaplan BS, Trompeter RS, Moake JL, eds. Hemolytic Uremic Syndrome and Thrombotic Thrombocytopenic Purpura. New York, NY: Marcel Dekker, Inc; 1992;10:499-512.
13. Sanders WE, Read MS, Reddick RL, Garris JB, Brinkhous KM. Thrombotic thrombocytopenia with von Willebrand factor deficiency induced by botrocetin: an animal model. Lab Invest. 1988;59:443-452. [Medline] [Order article via Infotrieve]
14.
Cramer EM, Caen JP, Drouet L, Breton-Gorius J.
Absence of tubular structures and immunolabeling for von
Willebrand factor in the platelet -granules from porcine von
Willebrand disease. Blood. 1986;68:774-778.
15. Meyer D, Girma JP. Von Willebrand factor: structure and function. Thromb Haemost. 1993;70:99-104. [Medline] [Order article via Infotrieve]
16.
Nichols TC, Bellinger DA, Reddick RL, Smith SV, Koch
GG, Davis K, Sigman J, Brinkhous KM, Griggs TR, Read MS. The
roles of von Willebrand factor and factor VIII in arterial thrombosis:
studies in canine von Willebrand disease and hemophilia A.
Blood. 1993;81:2644-2651.
17.
Brinkhous KM, Barnes DS, Potter JY, Read MS.
Von Willebrand syndrome induced by a Bothrops venom cofactor:
bioassay for venom coagglutinin. Proc Natl Acad Sci
U S A. 1981;78:3230-3234.
18. Brinkhous KM, Read MS. Preservation of platelet receptors for platelet aggregating factor/von Willebrand factor by air drying, freezing, or lyophilization: new stable platelet preparations for von Willebrand factor assays. Thromb Res. 1978;13:591-597. [Medline] [Order article via Infotrieve]
19. Eaton LA, Read MS, Brinkhous KM. Glycoprotein Ib bioassays: activity levels in Bernard-Soulier syndrome and in stored blood bank platelets. Arch Pathol Lab Med. 1991;115:488-493. [Medline] [Order article via Infotrieve]
20. Langdell RD, Wagner RH, Brinkhous KM. Effect of antihemophilic factor on one-stage clotting tests. J Lab Clin Med. 1953;41:637-647. [Medline] [Order article via Infotrieve]
21. Lamb MA, Reisner HA, Cooper HA, Wagner RH. The multimeric distribution of factor VIII-related antigen studied by an improved crossed-immunoelectrophoresis technique. J Lab Clin Med. 1981;98:751-763. [Medline] [Order article via Infotrieve]
22. Laurell CB. Quantitative estimation of proteins by electrophoresis in agarose gels containing antibodies. Anal Biochem. 1966;15:45-52. [Medline] [Order article via Infotrieve]
23. Aihara M, Sawada Y, Ueno K, Morimoto S, Yoshida Y, de Serres M, Cooper HA, Wagner RH. Visualization of von Willebrand factor multimers by immunoenzymatic stain using avidin-biotin peroxidase complex. Thromb Haemost. 1986;55:263-267. [Medline] [Order article via Infotrieve]
24. Ruggeri ZM, Zimmerman TS. The complex multimeric composition of factor VIII/von Willebrand factor. Blood. 1981;57: 1140-1143.
25. Mertz ET. The anomaly of a normal Duke's and very prolonged saline bleeding time in swine suffering from an inherited bleeding disease. Am J Physiol. 1942;136:360-362.
26.
Reddick RL, Griggs TR, Lamb MA, Brinkhous KM.
Platelet adhesion to damaged coronary arteries: comparison of
normal and von Willebrand diseased swine. Proc Natl Acad
Sci U S A. 1982;79:5076-5079.
27. Knibbs DR, Anderson C, Abbott SJ, Cartun RW. A simplified technique for the ultrastructural localization of cytoskeletal filament proteins by immunogold electron microscopy. J Histotechnol. 1990;13:9-12.
28. Read MS, Reddick RL, Bode AP, Bellinger DA, Nichols TC, Taylor K, Smith SV, McMahon DK, Griggs TR, Brinkhous KM. Preservation of hemostatic and structural properties of rehydrated lyophilized platelets: potential for long-term storage of dried platelets for transfusion. Proc Natl Acad Sci U S A. 1995;92:391-401.
29. Gangarosa EJ, Johnson TR, Ramos HS. Ristocetin-induced thrombocytopenia: site and mechanism of action. AMA Arch Intern Med. 1960;105:83-89.
30. Brinkhous KM, Fricke WA, Read MS. Determinants of von Willebrand factor activity elicited by ristocetin and botrocetin: studies on a human von Willebrand factor-binding antibody. Semin Thromb Hemost. 1985;11:337-341. [Medline] [Order article via Infotrieve]
31.
Sugimoto M, Mohri H, McClintock RA, Ruggeri ZM.
Identification of discontinuous von Willebrand factor sequences
involved in complex formation with botrocetin: a model for the
regulation of von Willebrand factor binding to platelet glycoprotein
Ib. J Biol Chem. 1991;266:18172-18178.
32. Berndt MC, Ward CM, Booth WJ, Castaldi PA, Mazurov AV, Andrews RK. Identification of aspartic acid 514 through glutamic acid 542 as a glycoprotein Ib-IX complex receptor recognition sequence in von Willebrand factor: mechanism of modulation of von Willebrand factor by ristocetin and botrocetin. Biochemistry. 1992;31:11144-11151. [Medline] [Order article via Infotrieve]
33. Titani K, Kumar S, Takio K, Ericsson LH, Wade RD, Ashida K, Walsh KA, Chopek JE, Fujikawa K. Amino acid sequence of human von Willebrand factor. Biochemistry. 1986;25:3171-3184. [Medline] [Order article via Infotrieve]
34.
Scott JP, Montgomery RR, Retzinger GS. Dimeric
ristocetin flocculates proteins, binds to platelets, and mediates von
Willebrand factor-dependent agglutination of platelets. J
Biol Chem. 1991;266:8149-8155.
35. Brinkhous KM, Smith SV, Read MS. Botrocetin: pathophysiology and use in study of von Willebrand factor and platelet receptor glycoprotein Ib. In: Tu AT, ed. Handbook of Natural Toxins: Reptile Venoms and Toxins. New York, NY: Marcel Dekker; 1991;5: 377-403.
36.
Cramer EM, Meyer D, Menn RL, Breton-Gorius J.
Eccentric localization of von Willebrand factor in an internal
structure of platelet -granule resembling that of Weibel-Palade
bodies. Blood. 1985;66:710-713.
37. Moake JL, Rudy CK, Troll JH, Weinstein MJ, Colannino NM, Hong SL, Koutcher JA, Melaragno AJ, Manner CE. Case report: von Willebrand factor abnormalities and endothelial cell perturbation in a patient with acute thrombotic thrombocytopenic purpura. Am J Med Sci. 1986;291:47-50. [Medline] [Order article via Infotrieve]
38.
Lian ECY, Harkness DR, Byrnes JJ, Wallach H, Nunez R.
Presence of a platelet aggregating factor in the plasma of
patients with thrombotic thrombocytopenic purpura and its inhibition by
normal plasma. Blood. 1979;53:333-337.
39. Brandt JT, Kennedy MS, Senhauser DA. Platelet aggregating factor in thrombocytopenic purpura. Lancet. 1979;2:463-464. Letter to the editor.
40. Baehr G, Klemperer P, Schifrin A. An acute febrile anemia and thrombocytopenic purpura with diffuse platelet thrombosis of capillaries and arterioles. Trans Assoc Am Physicians. 1936;51:43-58.
41. Lian ECY, Siddiqui FA, Chen SH, Feng LM, Li JZ. Platelet-agglutinating aggregating proteins from the plasma of patients with thrombotic thrombocytopenic purpura. In: Moake JL, Kaplan BS, Trompeter TS, eds. Hemolytic Uremic Syndrome and Thrombotic Thrombocytopenic Purpura. New York, NY: Marcel Dekker, Inc; 1992;10:473-481.
42. Lian ECY. Pathogenesis of thrombotic thrombocytopenic purpura. Semin Hematol. 1987;24:82-100. [Medline] [Order article via Infotrieve]
43. Byrnes JJ, Moake JL. Thrombotic thrombocytopenic purpura and hemolytic-uremic syndrome: evolving concepts of pathogenesis and therapy. Clin Haematol. 1986;15:413-442. [Medline] [Order article via Infotrieve]
44. Lian ECY, Siddiqui FA. Binding of platelet agglutinating protein p37 from the plasma of a patient with thrombotic thrombocytopenic purpura to human platelets. Thromb Haemost. 1991;65:96-101. [Medline] [Order article via Infotrieve]
45. Lian ECY, Siddiqui FA, Jamieson GA, Tandon NN. Platelet agglutinating protein p37 causes platelet agglutination through its binding to membrane glycoprotein IV. Thromb Haemost. 1991;65:102-106. [Medline] [Order article via Infotrieve]
46. Moake JL, Turner NA, Stathopoulos NA, Nolasco LH, Hellums JD. Involvement of large plasma von Willebrand factor multimers and unusually large vWF forms derived from endothelial cells in shear stress-induced platelet aggregation. J Clin Invest. 1986;78:1456-1461.
47.
Moake JL, Turner NA, Stathopoulos NA, Nolasco LH,
Hellums JD. Shear-induced platelet aggregation can be mediated
by vWF released from platelets, as well as by exogenous large or
unusually large vWF multimers, requires adenosine diphosphate, and is
resistant to aspirin. Blood. 1988;71:1366-1374.
48. Wilbourn B, Harrison P, Lawrie A, Savariau E, Savidge G, Cramer EM. Porcine platelets contain an increased quantity of ultra-high molecular weight von Willebrand factor and numerous alpha-granular tubular structures. Br J Haematol. 1993;83:608-615.[Medline] [Order article via Infotrieve]
This article has been cited by other articles:
 |
|
 |
|
  S. L. Haberichter, E. P. Merricks, S. A. Fahs, P. A. Christopherson, T. C. Nichols, and R. R. Montgomery Re-establishment of VWF-dependent Weibel-Palade bodies in VWD endothelial cells Blood, January 1, 2005; 105(1): 145 - 152. [Abstract] [Full Text] [PDF]
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||