Biomaterials, artificial cells, and immobilization biotechnology : official journal of the International Society for Artificial Cells and Immobilization Biotechnology最新文献

Enzyme-loaded microcapsules were prepared and treated with dimyristoylphosphatidylcholine molecules so as to control the permeation of substrates through the microcapsule membranes. The activities of enclosed enzymes increased with increase in ambient temperature, but gave an abrupt change at around the phase transition temperature of the lipid. The experimental results indicate the possibility of making artificial cells which respond to the temperature change of the surrounding medium.

In this work a new type of polyelectrolyte complex capsules is introduced as an artificial housing for liver cells. Male Wistar rat hepatocytes were encapsulated using cellulose sulphate and polydimethyldialyllammonium chloride as polyelectrolytes. Amino acid metabolism rate and urea synthesis of the cells increased over the investigation period in contrast to the decrease observed in control monolayer cultures. The encapsulated cells were morphologically characterized. The described procedure represents a sufficient method for the cultivation of living cells in mechanically stable semipermeable microcapsules.

The influences of 11 factors are studied. Molecular weight of the emulsifier, amount of wall material and amount of core material were found to be the most influential factors.

Nitrogen removal from wastewaters is a multiple step process in which nitrification is often a problem due to the slow growth rates of the nitrifying bacteria. By immobilization of these bacteria, nitrification can be efficiently accomplished in compact reactors. In this paper, the possibilities of integrated nitrification and denitrification within a single reactor system are evaluated. Two main systems are studied: a) Nitrosamines europaea and Pseudomonas denitrificans co-immobilized in a a gel bead and operated in an air-lift reactor; b) the same bacteria separately immobilized and operated in different compartments of a multiple gas-lift reactor.

Among the currently used LDL-apheresis techniques selective removal seems to be a better option. We have made a preliminary study on adsorption of LDL onto modified and bare chitosan and PVA beads. It seems that bare chitosan itself maybe an excellent adsorbent system for LDL. Further detailed studies are required to examine the specificity and selectivity in adsorption.

Perfluorocarbon (PFC) and lipid emulsions (eg. Fluosol, Intralipid,) containing phospholipid have been reported to modify platelet function after intravenous infusion. Platelet activation might be responsible for the generation of mediators responsible for PFC-induced side effects. In view of this, we investigated the effect of a highly concentrated perfluorocarbon emulsion, containing 90% (w/v) perfluorooctylbromide (perflubron,;PFOB), on porcine and human platelet activation and function. We measured both (1) stimulated ex-vivo porcine platelet aggregation pre and post infusion of either perflubron or control (vehicle only) emulsions and (2) stimulated in vitro human platelet calcium flux in the presence of perflubron emulsion or control emulsions. Platelet aggregation stimulated by collagen, ADP or arachadonic acid (AA) was inhibited in ex-vivo porcine platelets following infusion of perflubron emulsion at a dose of 3 ml/kg (0.2 ml/kg/min). Inhibition was dose-dependent and was decreased when the dose of perflubron emulsion was reduced to 1.0 or 0.3 ml/kg. Infusion of saline or "vehicle" emulsions had little or no effect on stimulated ex-vivo pig platelet aggregation. Fluosol infusion was associated with inconsistant inhibition of platelet aggregation. A23187- or AA-stimulated calcium flux of human platelets in vitro was inhibited in the presence of 1% (v/v) perflubron emulsion. Similar effects were seen with Fluosol, or Intralipid. This inhibition was agonist dose-dependent.(ABSTRACT TRUNCATED AT 250 WORDS)

Endothelial cell (EC) activation plays a key role in the inflammatory response by promoting the margination of leukocytes in inflamed loci. Augmented leukocyte margination to activated EC is mediated by the increased display of leukocyte adhesion molecules on EC surface membranes. The biocompatibility of synthetic oxygen-transport fluids is intimately linked to EC function, since one of the first tissues encountered by such fluids is the vascular endothelium. We investigated the effect of one such agent, a phospholipid-based perfluorocarbon emulsion containing 90% w/v perfluorooctyl bromide (perflubron, PFOB) on EC activation. Human umbilical vein EC (HUVEC) were activated by 5 U/ml interleukin-1 (IL-1), 20 U/ml tumor necrosis factor (TNF), or 50 ng/ml E coli endotoxin (LPS) in the presence or absence of up to 20%, w/v perflubron. HUVEC activation was monitored by the extent of up-regulation of expression of intercellular adhesion molecule-1 (ICAM) and endothelial-leukocyte adhesion molecule-1 (ELAM). Exposure of HUVEC to perflubron did not alter the upregulation of ICAM or ELAM in response to IL-1 or TNF (n = 20). However, at 10% perflubron ICAM upregulation in response to LPS was inhibited by 95 +/- 6% (n = 9; p < .05). ELAM expression was similarly affected. The concentration of perflubron required to diminish LPS-induced up-regulation by 50% was 6.0 +/- 0.6% (n = 3). The inhibitory effect of 10% perflubron was overcome by > 1 microgram/ml LPS (n = 3) and the inhibitory effect was attenuated by adding perflubron to the cultures after LPS. In agreement with the above, additional experiments showed that incubation of LPS with perflubron prevented LPS-induced stimulation of TNF synthesis by a murine macrophage (RAW) cell line (n = 3). We conclude: 1) perflubron neither activates HUVEC nor interferes with HUVEC activation by IL-1 or TNF, 2) perflubron prevented HUVEC activation by LPS in a dose and time-dependent manner, 3) perflubron prevented LPS-induced activation of more than one cell line. Taken together, the data suggest that perflubron may bind and sequester limited concentrations of LPS. Whether this property of perflubron also occurs upon in vivo infusion and whether it might be clinically useful in preventing some of the adverse effects of endotoxemia are unknown.

Samples of polyurethane (PU) foam from the Même breast implant were incubated at 37 degrees C in either 0.3-3.0 N sodium hydroxide (NaOH) solutions, normal saline, or methanol. The chemicals released were analyzed by gas chromatography (GC), gas chromatography/mass spectrometry (GC/MS), and Fourier-transform infra-red (FT-IR) spectroscopy. The surfaces of the treated and untreated foam samples were studied by scanning electron microscopy (SEM). The NaOH solutions hydrolysed the foam, releasing toluene diamine (TDA). Incubating the foam in methanol washed out trace quantities of anti-oxidant, 2,4-dimethyl-6-t-butylphenol (DBP). When the foam was incubated in normal saline at 37 degrees C no TDA was detectable but another compound with a mass ion of 173 was detected. Further GC/MS studies confirmed that this compound was polyol, one of the reagents used to manufacture the PU foam. Repeatedly incubating or washing the foam in normal saline or methanol eliminated the release of polyol. SEM studies of the foam samples before and after incubation experiments, showed no evidence of polymer degradation. These findings indicated that polyol was present in the PU foam only as an impurity or residue and did not originate from the breakdown of the foam itself.

Several methods for characterization of microcapsules developed in connection with optimizing and controlling the properties of capsules based on polyelectrolyte complexes (PEC) using sodium cellulosesulphate (NaCS) and poly(dimethyldiallylammonium chloride) (PDMDAAC) as complex forming components are briefly reported.

Liposomes represent for amphotericin B (AmB) a promising delivery system that may reduce the important toxicity of the drug. Liposomal AmB has a higher therapeutic index than AmB alone and allows to use larger doses. The mechanism of reduced toxicity may be related to a better targeting ability, a protective effect, and a selective transfer of liposomes. Anyway the liposomes intercalated AmB tends to be uptaken by organs that belong to the reticuloendothelial system, where fungi, the target cells, are localized.