Phase Stability in Hydroxyapatite / Barium Titanate Piezo Bioceramics

2008 ◽  
Vol 273-276 ◽  
pp. 1-7 ◽  
Author(s):  
Arda Aba ◽  
Celaletdin Ergun
Keyword(s):  
Barium Titanate ◽  
Phase Stability ◽  
Bone Adaptation ◽  
Mixing Ratios ◽  
Piezo Effect ◽  
Mixing Method ◽  
Electrical Polarity ◽  
Electric Signals

It has been reported in the biocompatibility researches performed in-vivo and in-vitro that the electric signals produced by piezoelectric implants may induce accelerated healing of the injured tissue after implantation. Barium titanate (BaTiO3; BTO), as a well known piezoelectric ceramic, is a suitable candidate to be used in these kind of biomedical researches about the effect of the electrical polarity and piezoelectricity on tissues. The excellent biocompatibility and faster bone adaptation characteristics of hydroxylapatite (HA) have been well documented in the literature. Therefore, HA / BTO composites may be a suitable bioceramic material introducing both the piezo effect and biocompatibility at the same time. However, the main point to process such composites should be to keep HA and BTO phases as stable as possible not to loose the biocompatibility of HA and the piezoelectricity of BTO ceramics. In this research HA / BTO, piezo-composites were prepared with powder mixing method in various mixing ratios and sintered at the temperatures between 500 and 1300 oC. Sintering was carried out under different atmospheres to evaluate the effect of atmosphere on the phase stability of composites. Then composites are characterized with XRD, DTA, density measurements and d33 piezoelectricty coefficient measurements.

The anterior and posterior ‘stomach’ regions of larval Aedes aegypti midgut: regional specialization of ion transport and stimulation by 5-hydroxytryptamine

1999 ◽  
Vol 202 (3) ◽  
pp. 247-252 ◽  
Author(s):  
T.M. Clark ◽  
A. Koch ◽  
D.F. Moffett
Keyword(s):  
Steady State ◽  
Aedes Aegypti ◽  
Ion Transport ◽  
Malpighian Tubules ◽  
Transport Mechanisms ◽  
Regional Specialization ◽  
Negative Deflection ◽  
Electrical Polarity

The ‘stomach’ region of the larval mosquito midgut is divided into histologically distinct anterior and posterior regions. Anterior stomach perfused symmetrically with saline in vitro had an initial transepithelial potential (TEP) of −66 mV (lumen negative) that decayed within 10–15 min to a steady-state TEP near −10 mV that was maintained for at least 1 h. Lumen-positive TEPs were never observed in the anterior stomach. The initial TEP of the perfused posterior stomach was opposite in polarity, but similar in magnitude, to that of the anterior stomach, measuring +75 mV (lumen positive). This initial TEP of the posterior stomach decayed rapidly at first, then more slowly, eventually reversing the electrical polarity of the epithelium as lumen-negative TEPs were recorded in all preparations within 70 min. Nanomolar concentrations of the biogenic amine 5-hydroxytryptamine (5-HT, serotonin) stimulated both regions, causing a negative deflection of the TEP of the anterior stomach and a positive deflection of the TEP of the posterior stomach. Phorbol 12,13-diacetate also caused a negative deflection of the TEP of the anterior stomach, but had no effect on the TEP of the posterior stomach. These data demonstrate that 5-HT stimulates region-specific ion-transport mechanisms in the stomach of Aedes aegypti and suggest that 5-HT coordinates the actions of the Malpighian tubules and midgut in the maintenance of an appropriate hemolymph composition in vivo.

Evaluation of Phase Stability in Zirconia Femoral Heads From Different Manufacturers After In Vitro Testing or In Vivo Retrieval

2009 ◽  
Vol 24 (8) ◽  
pp. 1225-1230 ◽  
Author(s):  
Kyoju Fukatsu ◽  
Giuseppe Pezzotti ◽  
Yasuhisa Hayaishi ◽  
Nobuhiko Sugano
Keyword(s):  
Phase Stability ◽  
In Vitro Testing ◽  
Femoral Heads

Red Jujube-Incorporated Gelatin Methacryloyl (GelMA) Hydrogels with Anti-Oxidation and Immunoregulation Activity for Wound Healing

2019 ◽  
Vol 15 (7) ◽  
pp. 1357-1370 ◽  
Author(s):  
Jun Huang ◽  
Long Chen ◽  
Zhipeng Gu ◽  
Jun Wu
Keyword(s):  
Antioxidant Activity ◽  
Wound Healing ◽  
Structural Characterization ◽  
Wound Dressing ◽  
Immune Stimulation ◽  
Hybrid Hydrogel ◽  
History Of ◽  
Mixing Method

Red jujube has a long history of consumption for its excellent antioxidant activity and immunoregulation. In this study, red jujube-incorporated gelatin-methacryloyl (GelMA) hydrogels were developed using a programmed mixing method for wound healing. A series of evaluations, including structural characterization, antioxidant activity in vitro and in vivo, immunoregulation, and wound healing effects, were conducted. The results indicated that the introduction of red jujube equipped the GelMA hydrogel with antioxidation ability and light immune-stimulation. The wound healing results further confirmed that red jujube hybrid hydrogel could be a promising wound dressing material.

scholarly journals Time-lapsed imaging of nanocomposite scaffolds reveals increased bone formation in dynamic compression bioreactors

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Gian Nutal Schädli ◽  
Jolanda R. Vetsch ◽  
Robert P. Baumann ◽  
Anke M. de Leeuw ◽  
Esther Wehrle ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Barium Titanate ◽  
Bone Formation ◽  
Animal Studies ◽  
Dynamic Compression ◽  
High Volume ◽  
Bone Scaffolds ◽  
Immunohistological Staining

AbstractProgress in bone scaffold development relies on cost-intensive and hardly scalable animal studies. In contrast to in vivo, in vitro studies are often conducted in the absence of dynamic compression. Here, we present an in vitro dynamic compression bioreactor approach to monitor bone formation in scaffolds under cyclic loading. A biopolymer was processed into mechanically competent bone scaffolds that incorporate a high-volume content of ultrasonically treated hydroxyapatite or a mixture with barium titanate nanoparticles. After seeding with human bone marrow stromal cells, time-lapsed imaging of scaffolds in bioreactors revealed increased bone formation in hydroxyapatite scaffolds under cyclic loading. This stimulatory effect was even more pronounced in scaffolds containing a mixture of barium titanate and hydroxyapatite and corroborated by immunohistological staining. Therefore, by combining mechanical loading and time-lapsed imaging, this in vitro bioreactor strategy may potentially accelerate development of engineered bone scaffolds and reduce the use of animals for experimentation.

Measurements of In Vivo Strains in the Rat Tail Vertebra

2002 ◽  
Author(s):  
Chi Hyun Kim ◽  
Erica Takai ◽  
Nicole Culella ◽  
X. Edward Guo
Keyword(s):  
Bone Fractures ◽  
Mechanical Load ◽  
Bone Adaptation ◽  
Physiological Strain ◽  
Age Related ◽  
Cortical Shell ◽  
Tail Vertebra ◽  
Rat Tail

The study of bone adaptation is important in understanding the etiology of age-related bone fractures, developing optimal designs for total joint replacements, and preventing bone loss during prolonged space flight. Numerous studies have attempted to quantify the relationship between mechanical loading and bone adaptation [1,2,3,4]. An in vivo rat tail vertebra model has been developed for trabecular bone adaptation studies where a controlled mechanical load can be applied to a whole vertebra [3]. The load levels applied in vivo were selected using in vitro strain gage measurements on cadaveric rat tails, resulting strains in the cortical shell of tail vertebrae within the physiological range. However, it is not clear what the physiological strain level in the rat tail vertebrae in vivo during normal cage activities is. In addition, the in vivo strain in the rat tail vertebra subjected to mechanical loads has not been quantified.

Responses of Bone Cells to Biomechanical Forces in Vitro

1999 ◽  
Vol 13 (1) ◽  
pp. 93-98 ◽  
Author(s):  
E.H. Burger ◽  
J. Klein-Nulend
Keyword(s):  
Nitric Oxide ◽  
Mechanical Loading ◽  
Cell Biology ◽  
Cellular Response ◽  
Fluid Shear Stress ◽  
Bone Structure ◽  
Bone Cells ◽  
Bone Adaptation

In this paper, we review recent studies of the mechanism by which mechanical loading of bone is transduced into cellular signals of bone adaptation. Current biomechanical theory and in vivo as well as in vitro experiments agree that the three-dimensional network of osteocytes and bone-lining cells provides the cellular basis for mechanosensing in bone, leading to adaptive bone (re)modeling. They also agree that flow of interstitial fluid through the lacunar-canalicular porosity of bone, as a result of mechanical loading, most likely provides the stimulus for mechanosensing, and informs the bone cellular network about the adequacy of the existing bone structure. Important signaling molecules involved in in vivo adaptive bone formation, as well as in in vitro cellular response to fluid flow, are nitric oxide and prostaglandins. The expression of key enzymes for nitric oxide and prostaglandin production in bone cells is altered by fluid shear stress in vitro. Together, these studies have increased our understanding of the cell biology underlying Wolff's Law. This may lead to new strategies for combating disuse-related osteoporosis, and may also be of use in understanding and predicting the long-term integration of bone-replacing implants.

Induction and Differentiation of Dental Epithelium in Vivo and in Vitro

1982 ◽  
Vol 40 ◽  
pp. 142-145
Author(s):  
E. J. Kollar
Keyword(s):  
Connective Tissue ◽  
Oral Mucosa ◽  
Basal Lamina ◽  
Functional Derivatives ◽  
Specific Source ◽  
Dental Epithelium ◽  
Connective Tissue Stroma

The differentiation and maintenance of many specialized epithelial structures are dependent on the underlying connective tissue stroma and on an intact basal lamina. These requirements are especially stringent in the development and maintenance of the skin and oral mucosa. The keratinization patterns of thin or thick cornified layers as well as the appearance of specialized functional derivatives such as hair and teeth can be correlated with the specific source of stroma which supports these differentiated expressions.

Ultrastructural Correlations between Clonal Human Tumor Colonies and in Vivo Neoplasms

1982 ◽  
Vol 40 ◽  
pp. 210-211
Author(s):  
M.J. Murphy ◽  
R.R. Price ◽  
J.C. Sloman
Keyword(s):  
Cultured Cells ◽  
Human Tumor ◽  
Cell Type ◽  
Tumor Mass ◽  
Initial Cell ◽  
Cloning Assay ◽  
Human Tumor Cloning ◽  
The Relationship

The in vitro human tumor cloning assay originally described by Salmon and Hamburger has been applied recently to the investigation of differential anti-tumor drug sensitivities over a broad range of human neoplasms. A major problem in the acceptance of this technique has been the question of the relationship between the cultured cells and the original patient tumor, i.e., whether the colonies that develop derive from the neoplasm or from some other cell type within the initial cell population. A study of the ultrastructural morphology of the cultured cells vs. patient tumor has therefore been undertaken to resolve this question. Direct correlation was assured by division of a common tumor mass at surgical resection, one biopsy being fixed for TEM studies, the second being rapidly transported to the laboratory for culture.

Ultrastructure of melanocyte-keratinocyte interactions and pigment transfer in vitro

1978 ◽  
Vol 36 (2) ◽  
pp. 650-651
Author(s):  
Raul I. Garcia ◽  
Evelyn A. Flynn ◽  
George Szabo
Keyword(s):  
Direct Injection ◽  
Skin Pigmentation ◽  
Freeze Fracture ◽  
Pigment Granule ◽  
Time Lapse ◽  
Ultrastructural Level ◽  
Lanthanum Tracer ◽  
A Cell

Skin pigmentation in mammals involves the interaction of epidermal melanocytes and keratinocytes in the structural and functional unit known as the Epidermal Melanin Unit. Melanocytes(M) synthesize melanin within specialized membrane-bound organelles, the melanosome or pigment granule. These are subsequently transferred by way of M dendrites to keratinocytes(K) by a mechanism still to be clearly defined. Three different, though not necessarily mutually exclusive, mechanisms of melanosome transfer have been proposed: cytophagocytosis by K of M dendrite tips containing melanosomes, direct injection of melanosomes into the K cytoplasm through a cell-to-cell pore or communicating channel formed by localized fusion of M and K cell membranes, release of melanosomes into the extracellular space(ECS) by exocytosis followed by K uptake using conventional phagocytosis. Variability in methods of transfer has been noted both in vivo and in vitro and there is evidence in support of each transfer mechanism. We Have previously studied M-K interactions in vitro using time-lapse cinemicrography and in vivo at the ultrastructural level using lanthanum tracer and freeze-fracture.

Sign in / Sign up

Export Citation Format

Share Document