Analysis of using interpulse intervals to generate 128-bit biometric random binary sequences for securing wireless body sensor networks.

Wireless body sensor network (WBSN), a key building block for m-Health, demands extremely stringent resource constraints and thus lightweight security methods are preferred. To minimize resource consumption, utilizing information already available to a WBSN, particularly common to different sensor nodes of a WBSN, for security purposes becomes an attractive solution. In this paper, we tested the randomness and distinctiveness of the 128-bit biometric binary sequences (BSs) generated from interpulse intervals (IPIs) of 20 healthy subjects as well as 30 patients suffered from myocardial infarction and 34 subjects with other cardiovascular diseases. The encoding time of a biometric BS on a WBSN node is on average 23 ms and memory occupation is 204 bytes for any given IPI sequence. The results from five U.S. National Institute of Standards and Technology statistical tests suggest that random biometric BSs can be generated from both healthy subjects and cardiovascular patients and can potentially be used as authentication identifiers for securing WBSNs. Ultimately, it is preferred that these biometric BSs can be used as encryption keys such that key distribution over the WBSN can be avoided.

[Effect of Chelerythrine on glucosyltransferase and water-insoluble glucan of Streptococcus mutans].

PURPOSE: To study the effect of Chelerythrine on glucosyltransferase and extra-cellular synthesis of water-insoluble glucan of Streptococcus mutans. METHODS: The Chelerythrine was used as the experimental group with concentrations ranging from 24.4microg/ml to 390.6microg/ml prepared with BHI broth medium with contained 2% glucose, and BHI culture medium was used as the control group. Streptococcus mutans was added to each group, after cultured for 24 hours in the test tubes, centrifugation was followed. The supernatants were divided into two batches. One batch of solutions was used to extract glucosyltransferase, Bradford method and Somogyi method were used to measure the content of total protein and enzyme activity, and the specific activity was calculated. Another batch of solutions was used to measure the content of water-insoluble glucan by anthrone method. The data was statistically analyzed by One-way ANOVA using SPSS13.0 software package. RESULTS: The glucosyltransferase and water-insoluble glucan of Streptococcus mutans decreased gradually with the increase of each concentration of Chelerythrine. There were highly significant differences among total sample groups, and between glucosyltransferase activity or specific activity of each experimental group and control group as well (P<0.01); Except for the group of 24.4microg/ml Chelerythrine, there were highly significant differences of water-insoluble glucan between each experimental group and control group (P<0.01).There was positive correlation between glucosyltransferase activity and water-insoluble glucan content (r=0.883, P<0.01). CONCLUSION: Chelerythrine could inhibit the glucosyltransferase and extra-cellular synthesis of water-insoluble glucan of Streptococcus mutans.

[Experimental study of the inhibitory effects of Chelidonium majus L. extractive on Streptococcus mutans in vitro].

PURPOSE: To study the inhibitory effects of Chelidonium majus L. extractive on the growth of Streptococcus mutans in vitro, and to explore its mechanism in caries prevention. METHODS: Streptococcus mutans 25175 was chosen as the experimental bacterium. The Chelidonium majus L. extractives chelidonine and chelerythrine were double diluted to different concentrations by two-fold dilution. The inhibitory effect of Streptococcus mutans was measured by slip diffusion method. The minimal inhibitory concentration(MIC) was also determined. 0.16% liquor hibitane was used as positive control. Spearman correlation was used for statistical analysis. RESULTS: Inhibition zone of Streptococcus mutans appeared in some concentration of chelerythrine, but no inhibition zone in each concentration of chelidonine. The MIC of chelerythrine was 0.78 mg/ml which determined by liquid culture medium. The concentration of chelerythrine was highly related to the inhibitory zone of Streptococcus mutans (r=0.99, P<0.01). CONCLUSION: The antibacterial activity of Chelidonium majus L. extractive chelerythrine on Streptococcus mutans was significant,and the antibacterial activity of the concentration 100 mg/ml was higher than that of 0.16% liquor hibitane (19.4 mm), indicating that chelerythrine can be used as an agent for prevention of dental caries.