Physical heterogeneity of hatching enzyme of the sea urchin, Strongylocentrotus purpuratus.
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Biomedical subjects
Publications and source records attributed to D Barrett.
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A protease, ;trypsinogenase', secreted in small amounts by the sea-urchin blastula, is assayed in two steps as an example of enzyme-amplifying kinetics. In reaction 1 the trypsinogenase catalyses the activation of trypsinogen to trypsin. In reaction 2 the trypsin catalyses the hydrolysis of N-alpha-toluene-p-sulphonylarginine methyl ester, at a rate that is linear with trypsinogenase concentration over a 20-fold range. Results are reproducible within a batch of zymogen, but each batch requires a separate standard curve.
1. A trypsinogen-activating enzyme is distinct from the chorion-dissolving enzyme of the sea-urchin blastula, but is secreted with it. 2. This ;trypsinogenase' does not attack N-alpha-toluene-p-sulphonylarginine methyl ester, and is not inhibited by concentrations of di-isopropyl phosphorofluoridate or 7-amino-1-chloro-3-toluene-p-sulphonamidoheptan-2-one that are 98% effective against trypsin. It requires a small amount of Ca(2+) for activity, but is inhibited by more, from as little as 1mm. 3. Enzymic activity is associated with a wide range of particle weights, some apparently as high as 15x10(6). The mean particle weight can be decreased by sonication. 4. Fresh trypsinogenase in the higher range of particle weights appears to be remarkably stable to heating, e.g. retaining full activity after boiling for 15min.
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The causes of escalating healthcare costs in the United States and many other industrial countries are well documented. Less evident are the structural factors that underlie the increases and their implications for the future. This paper discusses these structural factors, puts them in the context of the healthcare marketplace, and proposes a way to address them using a collaborative arrangement among all stakeholders in a healthcare system, called value-based partnering. To be successful, the effort must include not only final purchasers (such as employers or Medicare in the USA) but all stakeholders in a healthcare system. Each stakeholder must develop a value equation in terms that are meaningful to the others, and must identify opportunities for value-enhancing partnerships. The paper also identifies some of the impediments to value-based partnering and discusses ways to overcome them, including the need for senior management intervention within some stakeholder groups, and the importance of collaborative discussions among all stakeholders.
Childhood prostitution is an area that most health-care workers do not come into direct contact with other than through media coverage. It is difficult to obtain a national picture of the scale of the problems associated with childhood prostitution as research has been sparse, fragmented and mainly localized Health and social care professionals need to be aware of the factors that influence routes into prostitution such as childhood abuse, poverty and breakdowns in family relationships if they are to provide relevant and appropriate health promotion interventions. This article explores the social economical and political issues surrounding childhood prostitution, and highlights come interesting initiatives which have been implemented by health and social care professionals.
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Value-based partnering is designed to move the healthcare system beyond cost-based competition. It recognizes that the healthcare "product" is not a commodity and that much of the value in the system comes from relationships between and among four stakeholders: consumers, providers, health plans, and employers. Given the difficulty of measuring such benefits as quality of care, improved health status, and increased employee productivity, stakeholders within the system traditionally have focused on easily measurable financial considerations such as premium rates. This focus has led to a system that defines relationships in purely financial terms. In contrast, the value-based partnering model presented in this article recognizes the range of factors that stakeholders consider in their relationships with each other. This approach has the potential to change the nature of competition and presents opportunities for those organizations that can effectively partner with other stakeholders and demonstrate value, rather than just lower cost. Moreover, by recognizing the interdependencies among stakeholder groups, the approach creates a strategic reason for employers, health plans, providers, and consumers to exchange information and create long-term alliances.
The chief cellular consituents of CSF are the "free cells" of the pia-arachnoid, ependyma, and choroid. These cells are of diverse types, but have their mesenchymal origin in common. Usually they offer no difficulty in identification since they are predominantly histiocytic. However, these "free cells" may be morphologically changed in reaction to an appropriate stimulus, and may therefore be a source of error in diagnostic material. Cells having mesothelial characteristics are not found in the CSF compartment and therefore the term pia-arachnoid mesothelial cells appears inappropriate. The only neuroectodermal derivative that was easily identifiable was the choroidal cell. It is distinctive and unequivocal. We were unable to recognize ependymal cells in our present study. Glial cells (protoplasmic and fibrous astrocytes) and neurons can be recognized when neural tissue is penetrated in the process of collecting CSF.