Callus formation

Biomaterial scientists and engineers are currently investigating novel formulations and modifications of existing materials that elicit specific, timely, and desirable responses from surrounding cells and tissues to support the osseointegration of the next generation of orthopedic and dental biomaterials (Ratner, 1992). Enhanced deposition of mineralized matrix at the bone-implant interface provides crucial mechanical stability to implants. Proactive orthopedic and dental biomaterials could consist of novel formulations that selectively enhance osteoblast function (such as adhesion, proliferation and formation of calcium-containing mineral) while, at the same time, minimize other cell (such as fibroblast) functions that may decrease implant efficacy (e.g., fibroblast participation in callus formation and fibrous encapsulation of implants in vivo). 

Yasuda, T., Yajima, Y., and Yamada, Y., Induction of DNA synthesis and callus formation from tuber tissue of Jerusalem artichoke by 2,4-dichlorophenoxyacetic acid, Plant Cell Physiol., 15, 321-329, 1974. Yeoman, M.M., Tissue Culture and Plant Science, Street, H.E., Ed., Blackwell s, Oxford, 1974, pp. 1-17. Zubr, J. and Pedersen, H.S., Characteristics of growth and development of different Jerusalem artichoke cultivars, in Inulin and Inulin-containing Crops, Fuchs, A., Ed., Elsevier, Amsterdam, The Netherlands, 1993, pp. 11-19. 

To create explants, dormant Jerusalem artichoke tubers are typically cut into 25-mm-thick slices, from which cylinders of tissue are fashioned. Cylindrical shapes are favored because they can be uniformly reproduced and have a high ratio of surface area to volume that optimizes gas and nutrient exchange, and facilitates callus formation. A small size is desirable to maximize the number of explants obtained from the same tissue source. Jerusalem artichoke tuber explant size is typically around 2.4 by 2.0 mm. The minimum size is usually 8 mg and approximately 20,000 cells (Yeoman, 1973), although some reports have used smaller explant sizes (e.g., Caplin, 1963). 

V Bone fragility mild-to-moderate short stature no dentinogenesis imperfecta radioulnar synostosis hyperplastic callus formation Probably AD... 

Light microscopy and SEM were undertaken by the same method described in section 1.4.4. Cross section and SEM of adventitious shoots formed on the cultured root segments are shown in Fig. (25). These observation indicate that shoots were directly formed on the surface of cultured root segments without callus formation as those on the intemode segments. Therefore, the reason for variation in alkaloid contents (Table 11) may not be attributable to the callus formation. 

B4. Banta, J. V., Schreiber, R. R., and Kulik, W. J., Hyperplastic callus formation in osteogenesis imperfecta simulating osteosarcoma.. Bone Joint Surg. 53A, 115-122... 

We demonstrated that CF is strongly water soluble (Table 1), thus it is unlikely that CF(s) is (are) the more lipophilic factor(s) responsible for the promotion of callus formation from barley anther cultures (17). CF is resistant to boiling and to acidic and alkaline pH treatment (Table 2). 

Electret materials are meanwhile used in a large number of modern high-tech applications including microphones, acoustic sensors, transducers, radiation and pollution dosimeters, power generators, filters, and many more. Additionally, electret technology is of great interest in the field of biomaterials, for instance in callus formation and wound healing [10, 11], When used in cellular or in multilayer sandwich structures, polymer electrets can exhibit piezoelectricity. Such materials are ferroelectrets, as they show typical features of ferroelectric materials such as piezo-and pyroelectricity [12-17],... 

Growth and alkaloid production in callus cultures of R. serpentina were extensively studied by Ohta and Yatazawa (683). 2,4-D was found to induce callus formation and to promote growth, but ajmaline levels in the calli decreased with an increase of 2,4-D in the medium. Kinetin was necessary for alkaloid production. 

Secondary Healing Bone union with a callus formation. 

C10H9N5O, Mr 215.21, mp. 267°C. K. belongs to the cytokinin group and is a derivative of adenine it occurs in various higher plants and yeasts and acts as a cell division factor. Like the closely related zeatin, K. is still active at million-fold dilutions and is thus considered to be a plant hormone. K. is isolated from autoclaved, aqueous slurries of deoxyribonucleic acids and is sometimes considered to be an artefact. K. is used as a plant growth regulator and also for inducing callus formation in plant cell cultures, etc.. ... 

The known biological effects of auxin are numerous. In addition to cellular elongation, apical dominance and root initiation, the more important effects include callus formation, parthenocarpy, phototropism and geotropism. 

By about 24 days almost all of the stocks showed some leafing. For each of the sample groupings the ten best stocks, i.e., ten stocks showing the most leafing, were removed from the perlite and the roots counted. The top achievers were the polymers and the lowest the monomers (Table 5). Again, visual observation showed that the roots associated with the polymer-dipped stocks were markedly superior with respect to size and length. Callus formation was consistently good with the polymer-dipped samples. In fact, it appears that some roots formed v ithout the need for prior callus formation. 

Auxin, see also Indoleacetic acid callus formation and, VI, 239 8-Azaguanine, see under Guanazolo Azotobacter chroococcum, niacin content of, VI, 184, 185... 

Previous works carried out with stirred tank bioreactors reported that the damage of hairy roots by the impeller induced callus formation and consequently reduced the biomass production [65], To overcome this problem the bioreactor configuration was modified. A plastic mesh was placed forming a zigzag arrangement around the baffle in order to increase the surface where the roots could be trapped [28]. 

In nature, auxins are produced in apical and root meristems, young leaves, seeds and developing fruits, and their main functions are cell elonj tion and expansion, suppression of lateral buds, etc. (Opik RoUe, 2005). In somatic embryogenesis this is considered one of the most important elements producing cell polarity and asymmetrical cell division. In general, relatively high auxin concentrations (2,4-D, lAA, etc.) favor callus formation and the induction process (cell polarity). Afterwards, when the induction stage has been achieved, it is necessary to reduce or eliminate the auxins in order to initiate the bilateral symmetry and the expression of the somatic embryos. 

From our summary, it was obvious that 2,4-D is critical for callus initiation and embryogenic callus formation in ES, particularly when combined with the supplement of TDZ. 

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