IR Spectroscopic Investigation on Isomerization of Ionized Ethylene Glycol.

It has been known that photoionization of ethylene glycol generates protonated methanol when the ionization energy is in the vicinity of the vertical ionization energy. Although two different isomerization paths have been proposed for the protonated methanol production, the isomerization path has not yet been identified. To investigate the isomerization of ionized ethylene glycol, infrared (IR) predissociation spectroscopy based on vacuum ultraviolet photoionization is carried out for neutral and cationic ethylene glycol and partially deuterated isotopomer (HOCD2CD2OH). The IR spectroscopic results indicate that ionized ethylene glycol isomerizes to the protonated methanol-HCO complex, and the isomerization path involving the double proton transfer is identified. This isomerization path is also supported by the theoretical isomerization path search, which demonstrates that several reaction pathways are mutually intercommunicated.

New development of carbonate apatite-chitosan scaffold based on lyophilization technique for bone tissue engineering.

Carbonate apatite-chitosan scaffolds (CA-ChSs) were fabricated using the lyophilization technique. It was found that ChSs prepared with 200 mg chitosan powder (ChSs200) had well-structured three-dimensional architecture with high porosity and good retentive form without brittleness. In addition, it was shown that the number of osteoblast-like cells MC3T3-E1 proliferated on desalinated ChSs200 was larger than that on the non-desalinated ChSs200. CA-ChSs were fabricated by adding 100 mg carbonate apatite (CA) to 200 mg chitosan gels followed by freeze-drying (CA100ChSs200). SEM observation revealed that CA100ChSs200 had favorable three- dimensional porous structures. The number of living cells increased more rapidly on CA100ChSs200 prepared with different amounts of CA than on ChSs. ALP activity significantly increased after day 14 and reached a plateau after day 21 in ChSs200 and CA100ChSs200. It was concluded that newly developed CA100ChSs200 may be a possible scaffold material for tissue engineering.

Comparative evaluation of bone regeneration using spherical and irregularly shaped granules of interconnected porous hydroxylapatite. A beagle dog study.

PURPOSE: Bone regeneration stimulated by two different shapes of interconnected porous calcium hydroxyapatite (IP-CHA) granules was evaluated in the mandibles of 3 beagle dogs. METHODS: Deferent shapes of IP-CHA were used, spherical (spherical shaped IP-CHA granules) and irregular shapes (irregularly shaped IP-CHA granules). Two bone sockets (3mm in diameter and 5mm in depth) were prepared in the right edentulous mandible of each animal where right premolars had been extracted and sites healed for 3 months. The two types of IP-CHA were filled into the sockets to stimulate bone regeneration. New bone formation was evaluated histologically at 4, 8 and 12 weeks after filling. RESULTS: At 4 weeks, little bone formation was apparent in any of the bony sockets. At 8 weeks, newly formed bone was detected between the granules but not in the pores. In contrast, at 12 weeks, bone formation was clearly observed not only between the granules but also inside the granule pores. Comparing the two sites at 8 and 12 weeks, more bone formation was detected in sites receiving irregularly shaped IP-CHA than in sites receiving spherical IP-CHA. CONCLUSION: These results indicate that use of irregularly shaped IP-CHA may enhance bone regeneration. The results of this preliminary study suggest that irregularly shaped IP-CHA granules may have more possible usefulness than spherically shaped granules as a scaffold for bone regeneration.

Bone formation ability of carbonate apatite-collagen scaffolds with different carbonate contents.

Hydroxyapatite and carbonate apatites with different carbonate contents were synthesized, mixed with atelocollagen, and made into sponge scaffolds. The scaffolds were implanted into the bone sockets of the femurs of male New Zealand white rabbits for 2, 3, 12 and 24 weeks. carbonate apatite-collagen scaffold with 4.8 wt% carbonate content appeared to have similar crystallinity and chemical composition to human bone. When the scaffolds were implanted into the rabbit femurs, histological observation indicated that the carbonate apatites-collagen scaffolds with relatively higher carbonate contents were gradually deformed throughout the implantation period, and showed uniform surrounding bone after 24 weeks and could not be distinguished. The carbonate apatite-collagen scaffold with 4.8 wt% carbonate content showed the highest bone area ratio of all of the scaffolds. It is suggested that a carbonate apatite-collagen scaffold with carbonate content similar to that of human bone may have optimal bone formation ability.

Initial bone regeneration around fenestrated implants in Beagle dogs using basic fibroblast growth factor-gelatin hydrogel complex with varying biodegradation rates.

PURPOSE: The purpose of this study was to compare the effectiveness of fast and slow biodegradation of basic fibroblast growth factor (bFGF)-gelatin hydrogel complex on bone regeneration around fenestrated implants as a new augmentation drug delivery system. METHODS: Nine titanium implants (3.3mm diameter and 10mm length) were placed into the edentulous areas of the mandibles of three adult beagle dogs with four screws exposed at the upper buccal side. The effectiveness of bFGF-gelatin hydrogel complexes of varying degradation types used to cover implant screws without membrane were compared with 1 microg and 10 microg bFGF-98 wt% gelatin as the fast degradation type and 10 microg bFGF-95 wt% gelatin as the slow degradation type. After 4 weeks, bone regeneration around the screws was evaluated histologically and histomorphometrically. RESULTS: With use of 10 microg bFGF, regenerated bone around exposed screws was clearly seen in both the fast and slow degradation type groups. In contrast, little bone formation was seen in the fast degradation-type group with 1 microg bFGF. Height of regenerated bone for the slow degradation-type complex group was significantly greater than for the fast degradation-type group with 1 microg bFGF (P<0.05). CONCLUSION: These results suggest that use of slow degradation-type bFGF-gelatin hydrogel complex may accelerate bone regeneration around fenestrated implants at an early stage of bone regeneration.