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 ...

Bone regeneration and repair is a goal of many skeletal therapies and numerous agents positively or negatively impact these processes. New therapeutic agents and effective model systems are continually sought to identify agents and characterize their mechanisms of action are in con ...

Long considered a disease of post-menopausal women, osteoporosis is increasingly being recognized among the growing population of elderly men. Androgen deficiency may be associated with an increase of bone resorption in elderly men and so, with remodeling imbalance and fracture ris ...

Ovariectomy-induced osteopenia in the rat produces skeletal responses similar to that in a post-menopausal woman. In the ovariectomized (ovx) rat, high bone turnover, and subsequent bone loss, like in the human post-menopausal condition, can be prevented by estrogen replacement. Bec ...

Osteoblasts are the sole cell responsible for bone formation in vivo (1). Although genetic techniques have been extremely valuable to study the functions of certain genes in these cells in vivo, this approach is time consuming and expensive. An alternative loss-of-function approach that h ...

Adenoviruses have a number advantages as gene delivery vectors, including ability to transduce a wide variety of non-dividing and dividing cells with high efficiency, relative ease of construction, and ability to be purified as high-titer viral stocks. These characteristics make ade ...

Gene delivery by retroviruses is an easy and safe tool to stably over express a gene of interest and determine its role in a cell model. The gene of interest is cloned into the multiple cloning site of a retroviral vector that also contains a packaging signal and an antibiotic resistance marker for select ...

Normal cell growth and differentiation of bone cells requires the sequential expression of cell type specific genes to permit lineage specification and development of cellular phenotypes. Transcriptional activation and repression of distinct sets of genes support the anabol ...