Patricia F. E. M. Nievelstein

Bio: Patricia F. E. M. Nievelstein is an academic researcher from Utrecht University. The author has contributed to research in topics: Platelet adhesiveness & Adhesion. The author has an hindex of 11, co-authored 11 publications receiving 1210 citations.

Bicarbonate stimulated phospholipid scrambling induces cholesterol redistribution and enables cholesterol depletion in the sperm plasma membrane

Abstract: Mammalian sperm cells are activated prior to fertilization by high bicarbonate levels, which facilitate lipoprotein-mediated cholesterol efflux. The role of bicarbonate and cholesterol acceptors on the cholesterol organization in the sperm plasma membrane was tested. Bicarbonate induced an albumin-independent change in lipid architecture that was detectable by an increase in merocyanine staining (due to protein kinase A-mediated phospholipid scrambling). The response was limited to a subpopulation of viable sperm cells that were sorted from the non-responding subpopulation by flow cytometry. The responding cells had reduced cholesterol levels (30% reduction) compared with non-responding cells. The subpopulation differences were caused by variable efficiencies in epididymal maturation as judged by cell morphology. Membrane cholesterol organization was observed with filipin, which labeled the entire sperm surface of non-stimulated and non-responding cells, but labeled only the apical surface area of bicarbonate-responding cells. Addition of albumin caused cholesterol efflux, but only in bicarbonate-responding cells that exhibited virtually no filipin labeling in the sperm head area. Albumin had no effect on other lipid components, and no affinity for cholesterol in the absence of bicarbonate. Therefore, bicarbonate induces first a lateral redistribution in the low cholesterol containing spermatozoa, which in turn facilitates cholesterol extraction by albumin. A model is proposed in which phospholipid scrambling induces the formation of an apical membrane raft in the sperm head surface that enables albumin mediated efflux of cholesterol.

The role of platelet membrane glycoproteins Ib and IIb-IIIa in platelet adherence to human artery subendothelium

Abstract: Platelet adherence to human artery subendothelium in blood from eight normal subjects, four patients with Glanzmann's thrombasthenia (deficiency of platelet membrane glycoproteins IIb and IIIa: GPIIb-IIIa), two patients with Bernard-Soulier syndrome (deficiency of platelet membrane glycoprotein Ib: GPIb) and one patient with von Willebrand's disease (VWD subtype III. deficient in factor VIII-von Willebrand factor: FVIII-VWF) was compared at various wall shear rates (300, 500, 1000, 1800 and 2500 s-1). Platelet adherence in blood from the patients with Glanzmann's thrombasthenia was within the normal range at shear rates below 1000 s-1. There was some decrease in adhesion at higher shear rates and platelets were less spread out on the subendothelium than normally at all shear rates. Platelet aggregate formation was almost totally absent. Platelet adherence in blood from patients with the Bernard-Soulier syndrome was strongly impaired at all shear rates. Platelet adherence in blood from the patient with VWD subtype III was normal at shear rates of 300 and 500 s-1, but impaired at shear rates above 1000 s-1. Aggregate formation was also decreased at these shear rates. Platelet adhesion was strongly inhibited by a monoclonal antibody against glycoprotein Ib, which had previously been shown to inhibit ristocetin-induced aggregation, at shear rates of 500 and 1800 s-1 but not at 300 s-1. Platelet adhesion at 1800 s-1 was also inhibited, though to a lesser extent, by two antibodies against GPIIb-IIIa. These antibodies also inhibited platelet aggregate formation. The data indicates that GPIb is involved in adhesion at the same shear rates as von Willebrand factor. Absence or inhibition of GPIIb-IIIa primarily causes a defect of aggregate formation but GPIIb-IIIa may also play a role in adhesion, particularly at high shear rates. The defect of adhesion in the Bernard-Soulier syndrome may be dependent on factors other than a deficiency of GPIb alone.

Role of factor VIII-von Willebrand factor and fibronectin in the interaction of platelets in flowing blood with monomeric and fibrillar human collagen types I and III.

Abstract: Platelet adhesion to monomeric collagen types I and III, which were purified from human umbilical arteries, was studied in a perfusion chamber under well defined flow conditions. For this purpose, glass coverslips were coated with 20-30 micrograms/cm2 of collagen types I and III by spraying a solution of these collagens with a retouching air brush. Platelet deposition increased with the time of perfusion. Adhesion to both collagen types was similar in the first 3 min, but increased platelet deposition occurred on collagen type III after 3 min due to thrombus formation. Adhesion at a shear rate of 800 s-1 was strongly impaired with plasma of a patient with von Willebrand's disease or with fibronectin-free plasma. Addition of purified fibronectin to fibronectin-free plasma restored adhesion to the level obtained with normal plasma. Platelet deposition in normal plasma increased with increasing shear rates. Platelet deposition in VWD-plasma was normal at 490 s-1, but there was no increase at higher shear rates. Platelet deposition in fibronectin-free plasma was diminished at all shear rates studied from 490 to 1,300 s-1. Perfusion with a human albumin solution (HAS) to which purified Factor VIII-von Willebrand factor complex (FVIII-VWF) and fibronectin had been added gave similar platelet deposition as with normal plasma. Preincubation of collagen with FVIII-VWF and perfusion with HAS containing fibronectin, or, conversely, preincubation with fibronectin and perfusion with HAS containing FVIII-VWF, also resulted in adhesion similar to that observed in normal plasma. Similar adhesion was also observed after preincubation with both FVIII-VWF and fibronectin and subsequent perfusion with HAS alone. Sequential preincubations with first FVIII-VWF and then fibronectin, or with first fibronectin and then FVIII-VWF followed by perfusion with HAS, also gave a similar adhesion as observed with normal plasma. These data indicate that platelet adhesion to monomeric collagen types I and III is dependent on both FVIII-VWF and fibronectin. FVIII-VWF is only required at relatively high shear rates; fibronectin also at relatively low shear rates. Their complementary role in platelet adhesion suggests separate binding sites for FVIII-VWF and fibronectin on collagen. Platelet deposition on performed fibrils of collagen types I and III was also studied. Initial adhesion expressed as percentage surface coverage was similar to that found with monomeric collagen, but thrombus formation was much enhanced. Adhesion on fibrillar collagen at 800 s(-1) was impaired in VWD-plasma and fibronectin-free plasma, and was restored by addition of purified fibronectin to fibronectin-free plasma. When perfusions were performed with HAS, only addition of FVIII-VWF was required for optimal adhesion to fibrillar collagen; addition of fibronectin had no effect. These data are in contrast to the studies with monomeric collagens described above, in which the addition of both FVIII-VWF and fibronectin was required. These data are also in contrast to the observation that in plasma both FVIII-VWF and fibronectin are required for optimal adhesion to fibrillar collagen.

Subendothelial proteins and platelet adhesion. von Willebrand factor and fibronectin, not thrombospondin, are involved in platelet adhesion to extracellular matrix of human vascular endothelial cells.

Abstract: Endothelial cell matrix contained von Willebrand factor (VWF), fibronectin, and thrombospondin. The role of these proteins in the adhesion of platelets was investigated by preincubation of the matrix with specific antibodies and subsequent perfusion with human blood. When perfusions were performed with platelets in a human albumin solution (HAS) platelet adhesion was similar to that with normal plasma, indicating that proteins in the matrix can fully support adhesion. Preincubation of the matrix with a monoclonal antibody to VWF and perfusion with HAS showed a nearly complete inhibition of platelet adhesion at 1300 s-1, indicating a role for matrix-bound VWF at high shear rates and no requirement for VWF in plasma. Preincubation of the matrix with antihuman fibronectin F(ab')2 showed a slight inhibition of adhesion. The same result was obtained with perfusions with fibronectin-free plasma, and an untreated matrix. Preincubation with antifibronectin F(ab')2 and perfusion with fibronectin-free plasma showed a significant inhibition of platelet adhesion at all shear rates. These results indicate that fibronectin is required for adhesion at all shear rates. Preincubation of the matrix with different antibodies against human platelet thrombospondin showed no inhibition of platelet adhesion at all wall shear rates. Thrombospondin in the matrix is evidently not required for platelet adhesion.

Biomaterial-centered infection: microbial adhesion versus tissue integration.

Abstract: Biomaterials are being used with increasing frequency for tissue substitution. Complex devices such as total joint replacements and the total artificial heart represent combinations of polymers and metal alloys for system and organ replacement. The major barriers to the extended use of these devices are the possibility of bacterial adhesion to biomaterials, which causes biomaterial-centered infection, and the lack of successful tissue integration or compatibility with biomaterial surfaces. Interactions of biomaterials with bacteria and tissue cells are directed not only by specific receptors and outer membrane molecules on the cell surface, but also by the atomic geometry and electronic state of the biomaterial surface. An understanding of these mechanisms is important to all fields of medicine and is derived from and relevant to studies in microbiology, biochemistry, and physics. Modifications to biomaterial surfaces at an atomic level will allow the programming of cell-to-substratum events, thereby diminishing infection by enhancing tissue compatibility or integration, or by directly inhibiting bacterial adhesion.

Platelets in atherothrombosis

Abstract: The participation of platelets in atherogenesis and the subsequent formation of occlusive thrombi depend on platelets' adhesive properties and the inability to respond to stimuli with rapid activation. By understanding the multifaceted mechanisms involved in platelet interactions with vascular surfaces and aggregation, new approaches can be tailored to selectively inhibit the pathways most relevant to the pathological aspects of atherothrombosis.

Biochemistry and Genetics of von Willebrand Factor

Abstract: ▪ Abstract Von Willebrand factor (VWF) is a blood glycoprotein that is required for normal hemostasis, and deficiency of VWF, or von Willebrand disease (VWD), is the most common inherited bleeding disorder. VWF mediates the adhesion of platelets to sites of vascular damage by binding to specific platelet membrane glycoproteins and to constituents of exposed connective tissue. These activities appear to be regulated by allosteric mechanisms and possibly by hydrodynamic shear forces. VWF also is a carrier protein for blood clotting factor VIII, and this interaction is required for normal factor VIII survival in the circulation. VWF is assembled from identical ≈250 kDa subunits into disulfide-linked multimers that may be >20,000 kDa. Mutations in VWD can disrupt this complex biosynthetic process at several steps to impair the assembly, intracellular targeting, or secretion of VWF multimers. Other VWD mutations impair the survival of VWF in plasma or the function of specific ligand binding sites. This growing...