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Collagen is one of the most physiologically important agonists for platelet function. Two collagen-specific receptors, integrin α2β1 and glycoprotein (GP) VI, have been identified on the platelet surface from studying patient’s platelets deficient in one of these proteins (1,2). In ...

Methods of platelet permeabilization have been used for more than 20 yr as a means to study the role of various intracellular molecules in platelet function (1–3). Initially, permeabilization of platelets was used largely to introduce cations, nucleotides, and other small molecules into p ...

Collagen is the most abundant protein in vertebrates and has an essential structural role. Thus, the tensile strength of the fibrous collagens, types I, II, III, V, and XI, is fundamental to the function of bone, skin, tendons, cartilage, and blood vessel walls. Similarly, the network-forming colla ...

Botrocetin from the South American pit viper Bothrops jararaca was described as an activator of von Willebrand factor-dependent platelet aggregation by Read, Shermer, and Brinkhous in 1978 (1). Subsequently, botrocetin has been widely used as an important in vitro modulator in the analy ...

Nitric oxide was recognized fifteen years ago to be an endothelium-dependent relaxing factor with an important role in vasomotor control through its actions on vascular smooth muscle (1). Shortly after this discovery it was also demonstrated that nitric oxide (NO) is an inhibitor of platel ...

In this chapter we present two methods available to study the formation of nitrated proteins in blood platelets. We have used the methods in conjunction to first, identify proteins that become nitrated and second, to quantify the amounts of nitrated proteins present in platelets under a varie ...

Ion channels have fundamental roles in all cell types. Although fluorescent indicators can provide an indirect assessment of membrane conductances—for example, by studies of ion concentrations or membrane potential–our understanding of ion-channel activity ultimately re ...

Intracellular free Ca2+ is a key second messenger in virtually all cells. In unstimulated platelets and megakaryocytes, i is approx 100 nM and can be rapidly elevated by a variety of different agonists that activate phospholipase-C via heterotrimeric G proteins or receptor kinases (1–4). Ph ...

In just a few years, the green fluorescent protein (GFP) from the jellyfish Aequorea victoria has jumped from relative obscurity to become one of the most widely studied and exploited proteins in cell biology. Discovered by Shimomura et al. (1), GFP acts as a fluorophore and native companion to the fam ...

The use of inhibitors of signal transducers or signal modulators is essential for studies on intracellular signaling. A variety of pharmacological compounds is available to block the main pathways of signal transduction. These compounds, however, have limited specificity and cons ...

The challenge of working with platelet and megakaryocyte mRNA is contamination with leukocyte mRNA. When attempting to detect mRNA encoding platelet or megakaryocytic specific proteins using the extremely sensitive technique reverse transcription polymerase chain reac ...

Blood platelets are important components of hemostasis, contributing to healing of wounds by forming thrombi and to the initiation of repair processes. They are also involved, however, in the pathogenesis of life-threatening complications such as stroke or myocardial infarction. F ...

Efficient platelet cohesion (i.e., platelet aggregation) is necessary for the life-saving process of hemostasis. Plaque rupture and/or endothelial damage lead to exposure of collagens, retention of von Willebrand factor (vWF), and the adhesion of circulating platelets to the damag ...

The expression profile of the complete set of cellular genes or global gene expression provides a remarkable snapshot of physiological and pathophysiological mechanisms underlying cell regulation. Thus, accurate and precise measurements of global gene expression reveal uni ...

Bone homeostasis depends on balanced bone deposition and bone resorption, which are mediated by osteoblasts and osteoclasts, respectively. The process of bone turnover requires the coordination of these cells. Changes in the ability of either cell type to perform its function results in ...

Osteoblasts are the cells responsible for formation of new bone throughout life. Rats are one of the most widely studied mammalian species in skeletal biology and serve as useful models for many aspects of human skeletal physiology. The availability of genetically modified mice as research ...

Studies during the last decade demonstrated that apoptosis is as important as mitosis for the growth and maintenance of the skeleton and provided information on the significance and molecular regulation of apoptosis of bone cells. It is now known that: (1) all osteoclasts die by apoptosis aft ...

Bone formation is a complex process, and testing anabolic effects on the skeleton of agents is slow and expensive in animals. Neonatal mouse calvariae cultured ex vivo show strong anabolic or catabolic bone responses to 1-week treatments and can be analyzed by quantitative histomorphome ...

Intermittent parathyroid hormone (PTH) administration increases bone formation and bone mass and is being used as a therapy for osteoporosis. By contrast, chronic hyperparathyroidism results in the metabolic bone disease osteitis fibrosa characterized by local bone resorpt ...

In vivo assessment of bone formation (osteogenesis) potential by isolated cells is an important method for analysis of cells and factors control ling bone formation. Currently, cell implantation mixed with hydroxyapa-tite/tricalcium phosphate in an open system (subcutaneous i ...