Microspheres case studies

Peptide/Protein Encapsulated into Biodegradable Microspheres Case Study... 

PEPTIDE/PROTEIN ENCAPSULATED INTO BIODEGRADABLE MICROSPHERES CASE STUDY... 

CASE STUDIES OF DRUG DELIVERY FROM BIODEGRADABLE MICROSPHERES... 

As was the case with albumin, reports on clinical studies employing gelatin microspheres are limited and confined to Japan. Bleomycin, contained in a microsphere-in-oil formulation, was targeted to the lymph nodes for the treatment of infantile cystic hygroma, a benign tumor (143). Successful treatment was noted in all cases. 

More recently 211 At adsorbed on silver coated human serum albumin (HSA) microspheres has been used by Wunderlich, Doberenz and their colleagues46,94-99 to study the accumulation of the isotope in some tumour-bearing tissues of mice and pigs, and in one special case for human therapy100. 

Albertsson and coworkers [240-244] carried out extensive research to develop polymers in which the polymer properties are altered for different applications. The predominant procedure is ring-opening polymerization which provides a way to achieve pure and well defined structures. They have utilized cyclic monomers such as lactones, anhydrides, carbonates, ether-lactones. The work involved the synthesis of monomers not commercially available, studies of polymerization to form homopolymers, random and block copolymers, development of cross-linked polymers and polymer blends, surface modification in some cases, and characterization of the materials formed. The characterization is carried out with respect to the chemical composition and both chemical and physical structures, the degradation behavior in vitro and in vivo, and in some cases the ability to release drug components from microspheres prepared from the polymers. 

Wu et al. [ 176] studied the surface properties of PS and PMMA microspheres stabilized by the PEO macromonomer 7 (m=l) using dynamic light scattering, and claimed that for PMMA microspheres the surface area occupied by a PEO molecule is nearly twice as large as that for PS microspheres, assuming that 100% macromonomer is copolymerized to attach to the latex surface. However, this is not the case for styrene copolymerization with PEO macromonomers in which only 10% PEO macromonomer was copolymerized [131]. In contrast, it was confirmed that 100% of PEO macromonomers were copolymerized for the MM A and BMA dispersion copolymerization [132, 133]. 

The proteinoid microsphere (7) possesses a sufficient number of properties to permit its study in this context as a model for a primitive cell. In the case of the microsphere, the proteinoid material is itself catalytic. Metabolism is a functional expression of molecular structures, enzyme protein. This emphasis on polymers is clearest in the context of origins. The ways in which particulate structures, i.e., cells, contribute to and control such expression can be studied uniquely in the cell model. 

The efficacy of RA in PVR has been evaluated in animal models. A single intravitreal injection of RA used in conjunction with silicone oil reduces the incidence of traction retinal detachment (40). Use of microsphere encapsulation of RA to prolong the intravitreal half-life reduced the incidence of PVR in the rabbit model by 64% (41). Intravitreal RA suspended in 1% sodium hyaluronate has also been studied in a rabbit model of PVR and has similar inhibitory effect on PVR progression. The authors suggested that in cases in which silicone oil was not necessary, sodium hyaluronate could be used as an RA vehicle, though transient elevations of intraocular pressure could be expected (42). 

Vascular anastomotic communications between the uterine and ovarian arteries provide a route by which embolization materials can affect the ovarian blood supply and ovarian function, either permanently or temporarily [71], One case report describes embolic microspheres found within the ovarian arterial vasculature of a pathological specimen following uneventful UAE [66]. Unintentional embolization of the ovarian arteries is theorized to cause ovarian failure. However, the incidence of ovarian failure post UAE is no different to hysterectomy [100]. In fact, it is not clear whether UAE has any effect on ovarian function at all. There are studies that support its lack of effect [3,17,99,100] and a few case reports that document transient or permanent amenorrhea [92,98]. 

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