Effects of Alendronate on Bone Remodeling Around Osseointegrated Implants in Rats.

OBJECTIVE: To determine the effects of alendronate on bone remodeling around osseointegrated implants in rats. MATERIALS AND METHODS: The maxillary first molars were extracted from 36 male Sprague-Dawley rats, and replaced with customized implants. They were then administered twice-weekly subcutaneous injections of either alendronate (alendronate group) or saline (control group) after allowing a 4-week period for osseointegration. They were killed at 4, 8, or 12 weeks after the commencement of the injection protocol, and the implant sites were evaluated comprehensively by microcomputed tomographic, histologic, and biochemical assessments. RESULTS: It was hard to find statistically significant differences from microcomputed tomographic analyses. In addition, inconsistent variations were derived from histologic data. However, biochemical data showed statistically significant differences; serum osteocalcin level was statistically significantly lower in the alendronate group than in the control group at 8 weeks after the commencement of injections. In addition, serum osteocalcin level in the alendronate group was statistically significantly lower at 8 and 12 weeks after the initial injection point than at preinjection. CONCLUSIONS: The results suggest alendronate might affect bone remodeling activity around osseointegrated implants negatively, and serum osteocalcin could serve as an accessory tool to evaluate this effect.

Simultaneous detection of Streptococcus pneumoniae, S. mitis, and S. oralis by a novel multiplex PCR assay targeting the gyrB gene.

A multiplex PCR (mPCR) protocol was developed for simultaneous detection of the gyrB gene in Streptococcus pneumoniae, Streptococcus mitis, and Streptococcus oralis, and the specificity was evaluated using 141 coccus strains. Genomic DNAs purified from S. pneumoniae, S. mitis, and S. oralis strains were efficiently detected with size differences, whereas no PCR products were amplified from any of the reference strains tested. A pilot study of 47 human oral swab specimens was conducted in parallel, and the mPCR assay identified S. pneumoniae in 1 sample, S. mitis in 8 samples, and S. oralis in 2 samples, providing a powerful means for characterization at the level of species compared with traditional culture analysis. Our results suggest that the mPCR protocol presented here is a sensitive and promising tool for the rapid detection and discrimination of S. pneumoniae, S. mitis, and S. oralis from clinical specimens.

Development of micro-heaters with optimized temperature compensation design for gas sensors.

One of the key components of a chemical gas sensor is a MEMS micro-heater. Micro-heaters are used in both semiconductor gas sensors and NDIR gas sensors; however they each require different heat dissipation characteristics. For the semiconductor gas sensors, a uniform temperature is required over a wide area of the heater. On the other hand, for the NDIR gas sensor, the micro-heater needs high levels of infrared radiation in order to increase sensitivity. In this study, a novel design of a poly-Si micro-heater is proposed to improve the uniformity of heat dissipation on the heating plate. Temperature uniformity of the micro-heater is achieved by compensating for the variation in power consumption around the perimeter of the heater. With the power compensated design, the uniform heating area is increased by 2.5 times and the average temperature goes up by 40 °C. Therefore, this power compensated micro-heater design is suitable for a semiconductor gas sensor. Meanwhile, the poly-Si micro-heater without compensation shows a higher level of infrared radiation under equal power consumption conditions. This indicates that the micro-heater without compensation is more suitable for a NDIR gas sensor. Furthermore, the micro-heater shows a short response time of less than 20 ms, indicating a very high efficiency of pulse driving.