Biologically active materials, controlled

Baker, R., Controlled Release of Biologically Active Materials, John Wiley and Sons, New York, 1987. 

A block copolymer effective as a controlled release agents of biologically active materials have been prepared. This agent consisted of ethylene oxide-propylene sulfide-ethylene oxide teipolymer that had been end-capped with a selected cysteine-containing peptide. These materials resist degradation prior to reaching their intended targets because they behave as multilamellar vesicles. 

The purpose of this Section is to complement Sections VIII-XII, as some insoluble derivatives have been produced in entirely analogous ways, but do not fall within the categories previously discussed. The principal references are summarized in Table VIII, and such derivatives have been used as controls for immunoadsorbent and related experiments,ion-exchangers, " enzyme substrates, insoluble coenzymes, insoluble, biologically active materials, " and determination of the capacities of polysaccharide derivatives for general insolubilization, "... 

Like biological cells, artificial cells contain biologically active materials. However, the content of artificial cells can be more varied than biological cells (Figure 41.1). The membranes of artificial cells also can be extensively varied using synthetic or biological materials. Permeability can be controlled over a wide range, and this allows the enclosed material to be retained and separated from... 

Biodegradable hydrogels have also been developed for use in controlled drug delivery as carriers of biologically active materials such as hormones, enz5mes, antibiotics, antineoplastic agents, and cell suspensions. Temporary preservation of functional properties of a carried species, as well as the controlled release of the species into local tissues or systemic circulation, have been achieved. 

Engstrom, S., Lindman, B., and Larsson, K., 1992, Method of preparing controlled release preparations for biologically active materials and resulting compositions, U.S. Patent 5,151,272, September 29,1992. 

The posterior lobe of the pituitary, ie, the neurohypophysis, is under direct nervous control (1), unlike most other endocrine organs. The hormones stored in this gland are formed in hypothalamic nerve cells but pass through nerve stalks into the posterior pituitary. As early as 1895 it was found that pituitrin [50-57-7] an extract of the posterior lobe, raises blood pressure when injected (2), and that Pitocin [50-56-6] (Parke-Davis) causes contractions of smooth muscle, especially in the utems (3). Isolation of the active materials involved in these extracts is the result of work from several laboratories. Several highly active posterior pituitary extracts have been discovered (4), and it has been deterrnined that their biological activities result from peptide hormones, ie, low molecular weight substances not covalendy linked to proteins (qv) (5). 

A variety of containment strategies employ floating solid objects to control the rate of gaseous emissions from surface impoundments. These include synthetic membrane covers, rafts, and hollow plastic spheres. Synthetic membrane covers are feasible where the out-gassing of volatiles due to biological activity is not expected. Selection of the liner material must be... 

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