The mechanism of the apatite formation on the bioceramic surface was intensively studied and was considered crucial in designing the new biomaterials. The results obtained in this work indicate that N-CP/PLGA may be a good candidate for application to bone regeneration.
Amino-amide type local anesthetics, which have been most frequently used in clinical anesthesia are lidocaine, prilocaine, bupivacaine, ropivacaine and mepivacaine. These drugs show different clinical properties depending on their structures. In clinical praxis bupivacaine and mepivacaine are used as racemic mixtures. The stereochemistry of these two local anesthetic affects considerably the pharmacological action and toxicity. R(+) bupivacaine is 7 times more potent in blocking the sodium channels than the S(-)-enantiomer. Levobupivacaine and ropivacaine provide nerve blocking characteristics similar to those of racemic bupivacaine in almost all regional anesthesia techniques. The potency of bupivacaine is proportional to the toxic effects on cardiovascular system and central nervous system. Since these local anesthetic compounds are toxic, causing cardiovacular and central-nervous disorders, the therapeutic bloodplasma/serum concentrations should not exceed certain limits.
Bone tissue reconstruction and reparation is a big challenge in medicine. Biocomposite materials based on hidroxyapatite are widely used in reparation of bone defects. Adult bone marrow-derived stem cells may be considered in two categories: hematopoietic stem cells (HSC) from the bone marrow and mesenchymal stem cells from the bone marrow stroma (BMSC). HSC and BMSC do not only coexist in one organ, but functionally cooperate. BMSC have a critical role in the formation of hematopoietic microenvironment (HME). The aim of this study was to investigate the interactions between bone marrow cells and biocomposites based on HAp/PLLA (hidroxyapatite/poly-L-lactide) after subcutaneous implantation in Balb/c mice. In that purpose, bone marrow cells of Balb/c mice were seeded in HAp/PLLA tubes (15 mm×1,5 mm). The HAp/PLLA tubes with BMC was subcutaneously implanted with a needle into the intrascapsular region of the mouse. Implants were extracted after 2, 6 and 12 weeks. In implants after 2 and 6 weeks we found angiogenesis, collagenogenesis and new bone. Ectopic hematopoiesis was seen in implants after 12 weeks from implantation. As a good scaffold in the role of supporting osteogenesis and hematopoiesis, biocomposites HAp/PLLA can be good bone substitute materials in the bone reparation process. These results showed that the HAp/PLLA scaffold owned biological properties comparable to natural bone
The purpose of biomaterials is to replace a part or a function of the body in a safe, physiologically and economically acceptable way. The process of the reconstruction of bone defects has always been a big problem in orthopedics and maxillofacial surgery. Since hydroxyapatite (HAp) was detected as a component, the predominant constituent and the integral element of Mammalian bones, the development of the phospate ceramics as potential materials for implantation was enabled. This study investigated whether and in which way biomaterial calcium hydroxyapatite/poly-L-lactide (HAp/PLLA) interacts with the ionic composition of the human plasma. The simulated body fluid (SBF) is an artificial fluid that has the ionic composition and ionic concentration similar to the human blood plasma. HAp/PLLA was incubated for 1, 2, 3 and 5 weeks in SBF. The surfaces of both treated and untreated materials were analyzed on a scanning electron microscopy (SEM), and were also exposed to the energy dispersive X-ray spectroscopy (EDS), while SBF was submitted to the measuring of pH and electrical conductivity. However, our results indicate that the degradational changes of the material HAp/PLLA in SBF start from the surface of the treated material and that observed changes are the consequence of dissolution of its polymer component and the precipitation of the material similar to hydroxyapatite on its surface. This material shows good characteristics that place it among good candidates for the application in orthopedics and maxillofacial surgery.
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