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- Dasmah, Amir, et al.
(författare)
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Simultaneous or Delayed Placement of Surface Modified and Fluoridated Dental Implants into Autogenous Block Bone Grafts : A Histologic and Biomechanical Study in the Rabbit
- 2015
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Ingår i: Clinical Implant Dentistry and Related Research. - : Wiley. - 1523-0899 .- 1708-8208. ; 17:2, s. 395-401
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Tidskriftsartikel (refereegranskat)abstract
- Background: A delayed approach is recommended for reconstruction of the jaws with autogenous bone grafts and dental implants. Experimental studies have shown stronger bone tissue responses to surface modified implants than to nonmodified ones. AimThe aim of the study was to evaluate bone integration and stability of surface modified and fluoridated implants when placed with fresh or healed autogenous bone grafts. Material and Methods: Six rabbits were used in this study. Each right rabbit tibia (control) received an autogenous bone graft, harvested from the calvarium. Eight weeks later, a second graft was harvested from the other side of the calvarium and placed on the left tibia (test) with an implant. Another implant was installed in the healed graft of the right tibia. TiO2-blasted and fluoridated OsseoSpeed(TM) implants (Astra Tech AB, Molndal, Sweden), 3.5mm in diameter and 9mm long, were used. After additional 8 weeks, the rabbits were sacrificed and the implants were removed en bloc for light-microscopic analysis. Bone-to-implant contact (BIC) was registered as well as the amount of bone filling a rectangle indicating a region of interest (ROI). Resonance frequency analysis (RFA) was conducted both at the time of surgery and at the end of the experiment. ResultsThere were no statistically significant differences either in BIC or ROI between the test and control sides. RFA showed higher implant stability for the control side at the time of the surgery, but the difference had leveled out at the time of the sacrifice. Conclusion: The present study showed similar bone tissue responses and stability for surface modified and fluoridated implants after 8 weeks of healing in fresh or healed autogenous bone grafts.
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| 2. |
- Aidemark, Mari, et al.
(författare)
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Regulation of callose synthase activity in situ in alamethicin-permeabilized Arabidopsis and tobacco suspension cells
- 2009
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Ingår i: BMC Plant Biology. - : Springer Science and Business Media LLC. - 1471-2229. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Background: The cell wall component callose is mainly synthesized at certain developmental stages and after wounding or pathogen attack. Callose synthases are membrane-bound enzymes that have been relatively well characterized in vitro using isolated membrane fractions or purified enzyme. However, little is known about their functional properties in situ, under conditions when the cell wall is intact. To allow in situ investigations of the regulation of callose synthesis, cell suspensions of Arabidopsis thaliana (Col-0), and tobacco (BY-2), were permeabilized with the channel-forming peptide alamethicin. Results: Nucleic acid-binding dyes and marker enzymes demonstrated alamethicin permeabilization of plasma membrane, mitochondria and plastids, also allowing callose synthase measurements. In the presence of alamethicin, Ca2+ addition was required for callose synthase activity, and the activity was further stimulated by Mg2+ Cells pretreated with oryzalin to destabilize the microtubules prior to alamethicin permeabilization showed significantly lower callose synthase activity as compared to non-treated cells. As judged by aniline blue staining, the callose formed was deposited both at the cell walls joining adjacent cells and at discrete punctate locations earlier described as half plasmodesmata on the outer walls. This pattern was unaffected by oryzalin pretreatment, showing a quantitative rather than a qualitative effect of polymerized tubulin on callose synthase activity. No callose was deposited unless alamethicin, Ca2+ and UDP-glucose were present. Tubulin and callose synthase were furthermore part of the same plasma membrane protein complex, as judged by two-dimensional blue native SDS-PAGE. Conclusion: Alamethicin permeabilization allowed determination of callose synthase regulation and tubulin interaction in the natural crowded cellular environment and under conditions where contacts between the cell wall, the plasma membrane and cytoskeletal macromolecules remained. The results also suggest that alamethicin permeabilization induces a defense response mimicking the natural physical separation of cells (for example when intercellulars are formed), during which plasmodesmata are transiently left open.
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