1,720,979 research outputs found
Can a Bacterial Endotoxin be a Key Factor in the Kinetics of Amyloid Fibril Formation?
No full textData found in literature have reported that bacterial endotoxins may be involved in the inflammatory and pathological processes associated with amyloidosis and Alzheimer's disease (AD). In fact, it has been observed that the chronic infusion of the bacterial lipopolysaccharide, the outer cell wall component of Gram negative bacteria, into the fourth ventricle of rats reproduces many of the inflammatory and pathological features seen in the brain of AD patients. In this context, a key player in the pathogenesis of AD is the amyloid-β peptide (Aβ) that is capable of aggregating in fibrils that represent the main component of amyloid plaques. These deposits that accumulate among brain cells are indeed one of the hallmarks of AD. This aggregation in fibrils seems to correlate with Aβ toxic effects. However, recent data have shown that amyloid fibril formation not only results in toxic aggregates but also provides biologically functional molecules; such amyloids have been identified on the surface of fungi and bacteria. The aim of this work was to gain insight into the influence of bacterial endotoxins on Aβ fibrillogenesis; factors that influence fibril formation may be important for Aβ toxic potential. Following three days of incubation at 37°C, Aβ was organized in compact fibrils and the in vitro Aβ fibrillogenesis was potentiated by the Escherichia coli endotoxin. This suggests the importance of infectious events in the pathogenesis of AD and proposes a new aspect related to the putative pathological factors that can be implicated in the mechanisms involved in Aβ25-35 fibrillogenesis
Negative stain in trasmission electron microscopy investigation in the characterization of colloidal drug delivery systems
No full textOsteogenic differentiation of adipose tissue-derived stem cells cultured on trabecular titanium scaffolds
No full textInfluence of glutaraldehyde on drug release and mucoadhesive properties of chitosan microspheres
No full textAmong bioadhesive drug delivery systems, chitosan microspheres can be considered useful formulations for mucosal administration of drugs. The feasibility of modulating drug release from chitosan microparticles is due to polymer cross-linking, i.e. by glutaraldehyde. The
aim of this work was to develop a new simple ‘in vitro’ technique based on electron microscopy in order to study the effect of polymer crosslinking density on mucoadhesive properties of the chitosan microspheres. This technique consists of scanning electron microscopy (SEM)
and transmission electron microscopy (TEM) observations on morphological changes of chitosan microspheres with various cross-linking densities in contact with mucin solution. The results of SEM and TEM analyses have permitted to confirm the high affinity for mucin of
uncross-linked chitosan microspheres and thus their bioadhesive properties. Moreover, bioadhesive characteristics of the microparticulate drug delivery systems were depressed for glutaraldehyde cross-linked chitosan microspheres
Human adipose-derived stem cells (hASCs) in osteogenic medium on PLGA, PLGA/HA and titanium scaffolds
No full textEffect of shear stress on SAOS-2 osteoblasts bone matrix production inside a polyurethane porous scaffold
No full textHuman adipose-derived stem cells (hASCs) proliferate and differentiate in osteoblast-like cells on trabecular titanium scaffolds
Full text linkAbstract
The use of stem cells in regenerative medicine is an appealing area of research that has received a great deal of interest in recent years. The population called human adipose tissue-derived stem cells (hASCs) share many of the characteristic of its counterpart of marrow including extensive proliferative potential and the ability to undergo multilineage differentiation along classical mesenchymal lineages: adipogenesis, chondrogenesis, osteogenesis, and myogenesis. The aim of this study was to evaluate with biochemical and morphological methods the adhesion and differentiation of hASCs grown on trabecular titanium scaffolds. The hASCs isolated from subcutaneous adipose tissue after digestion with collagenase were seeded on monolayer and on trabecular titanium scaffolds and incubated at 37 degrees C in 5% CO(2) with osteogenic medium or control medium.The results showed that hASCs were able to adhere to titanium scaffolds, to proliferate, to acquire an osteoblastic-like phenotype, and to produce a calcified extracellular matrix with protein, such as, decorin, fibronectin, osteocalcin, osteonectin, osteopontin, and type I collagen. These data suggest that this kind of scaffold/cells construct is effective to regenerate damaged tissue and to restore the function of bone tissue
Improved cell growth by Bio-Oss/PLA scaffolds for use as a bone substitute
Full text linkThe objective of this study was to investigate the surface modification of a natural bone substitute, Bio-Oss, coated with a synthetic polymer poly-D,L-lactide (PLA), in order to improve cell growth. Bio-Oss is a natural bone substitute made of the mineralized portion of bovine bone. The material is used mainly to fill bone defects in periodontal and maxillofacial surgery and permit reossification. Poly-a-hydroxyacids such as polylactic acid are receiving an increasing attention due to their ability to retain a great quantity of water, good biocompatibility, low interfacial tension, and minimal mechanical and frictional irritation. All of these features are appealing from the perspective of bioenvironmental mimicking. The human osteosarcoma cell line SAOS-2 was added to the top of scaffolds uncoated or coated with PLA and incubated at 37° in 5% CO_{2} for 15 days. PLA-coated scaffolds improved cell growth. Polymer degradation behaviour, extraction and measurement of the extracellular matrix proteins of the cultured scaffolds (such as decorin, fibronectin osteocalcin, osteonectin, osteopontin and type-I and type-III collagen), immunolocalization of bone proteins and morphological analysis of the scaffolds confirmed the bioactive properties of Bio-Oss/PLA4M suggesting that it could be a valuable grafting materia
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