Finite element analyses were performed for various shapes of dental implant to study effects on stress distribution generated in the surrounding jaw bone and to determine an optimal thread shape for even stress distribution. It was found that the square thread shape filleted with a small radius was more effective on stress distribution than other dental implants used in the analyses. Additional analyses were performed on the implant with the thread shape obtained from previous analyses for varying other design parameters, such as the width of thread end and height of thread for various load directions, to determine the optimal dimensions of the implant. Stress distribution was more effective in the case when the width of thread end and the height of thread were 0.5p and 0.46p, respectively, where p is the screw pitch. Then, using the optimal implant thread dimensions determined previously, stress analyses were performed with various screw pitches and implant lengths, to investigate effects on stress distribution and to find the way to reduce the maximum effective stress generated in the jaw bone. Results show that the maximum effective stress decreased not only as screw pitch decreased gradually but also as implant length increased.

In conclusion, ErhBMP-2-loaded ACS showed enhanced osteoinductive potential, particularly with regard to bone closure of a sinus window and facilitated maturation of the newly formed bone within the rabbit sinus cavity. However, the structural durability of ACS was not sufficient to maintain the augmented volume in the sinus.

ObjectivesHeart rate variability (HRV) has gained recognition as a noninvasive marker of autonomic activity. HRV is considered a promising tool in various clinical scenarios. The optimal electrocardiogram (ECG) sampling frequency required to ensure sufficient precision of R–R intervals for HRV analysis has not yet been determined. Here, we aimed to determine the acceptable ECG sampling frequency range by analyzing ECG signals from patients who visited an emergency department with the chief complaint of acute intoxication or overdose.MethodsThe study included 83 adult patients who visited an emergency department with the chief complaint of acute poisoning. The original 1,000-Hz ECG signals were down-sampled to 500-, 250-, 100-, and 50-Hz sampling frequencies with linear interpolation. R–R interval data were analyzed for time-domain, frequency-domain, and nonlinear HRV parameters. Parameters derived from the data on down-sampled frequencies were compared with those derived from the data on 1,000-Hz signals, and Lin's concordance correlation coefficients were calculated.ResultsDown-sampling to 500 or 250 Hz resulted in excellent concordance. Signals down-sampled to 100 Hz produced acceptable results for time-domain analysis and Poincaré plots, but not for frequency-domain analysis. Down-sampling to 50 Hz proved to be unacceptable for both time- and frequency-domain analyses. At 50 Hz, the root-mean-squared successive differences and the power of high frequency tended to have high values and random errors.ConclusionsA 250-Hz sampling frequency would be acceptable for HRV analysis. When frequency-domain analysis is not required, a 100-Hz sampling frequency would also be acceptable.

The primary structure of 18S rRNA of the Novikoff hepatoma cells was investigated. Regardless of whether the primary sequence of 18S rRNA is finally determined by RNA sequencing methods or DNA sequencing methods, it is important to identify numbers and types of the modified nucleotides and accordingly the present study was designed to localize the modified regions in T1 RNase derived oligonucleotide. Modified nucleotides found in 66 different oligonucleotide sequences included 2 m62A, 1 m6A, 1 m7G, 1m1cap3psi, 7 Cm, 13 Am, 9 Gm, 11 Um, and 38 psi residues. A number of these modified nucleotides are now placed in defined sequences of T1 RNase oligonucleotides which are now being searched for in larger fragments derived from partial T1 RNase digests of 18S rRNA. Improved homochromatography fingerprinting (Choi et al. (1976) Cancer Res. 36, 4301) of T1 RNase derived oligonucleotides provided a distinctive pattern for 18S rRNA of Novikoff hepatoma ascites cells. The 116 spots obtained by homochromatography contain 176 oligonucleotide sequences.

This study evaluated the osteoinductive effect of the recombinant human bone morphogenetic protein-2 (rhBMP-2)-coated biphasic calcium phosphate (BCP) carrier system on the grafted sinus area, including surrounding tissues and the Schneiderian membrane. A total of 18 male rabbits were used in this study; two for in vitro and 16 for in vivo experiments. Schneiderian membranes taken from two animals were cultured with or without rhBMP-2, and quantitative reverse transcriptase-polymerase chain reaction analysis was performed. Both maxillary sinuses in each of the 16 animals were used to compare the in vivo effects of rhBMP-2-coated BCP (experimental group) and BCP alone (control group). In each animal, rhBMP-2-coated BCP was grafted into one of the maxillary sinuses, and the same amount of BCP alone was grafted into the contralateral site in random order. Radiologic and histometric analyses were performed at 2 and 8 weeks after surgery. After 2 days of culturing with or without rhBMP-2, a significant increase in the expression of early osteoblasts (RUNX2, type I collagen, alkaline phosphatase, and osteopontin) could be observed. Different histologic healing patterns were observed in experimental and control sites: newly formed bone lining the reflected sinus membrane without bone formation was observed at the central areas of experimental sites (window=0.06%; center=0%; membrane=20.86% of new bone), whereas evenly distributed new bone formation was observed at the control sites (window=7.27%; center=7.41%; membrane=15.58% of new bone).The augmented volume was well maintained at both the experimental and control sites during the experimental period, but at 2 weeks, the augmented volume was greater at the experimental sites than at the control sites (232.62 and 195.29 mm(3), respectively; p<0.001). These results suggest that good space maintenance in sinus augmentation is achieved with BCP, while the osteoinductive potential of the sinus membrane is activated at the early stage of healing with rhBMP-2.