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ABSTRACT: IPsec has become a very popular Internet security infrastructure today. As a new key exchange protocol of IPsec, to some extent, IKEv2 can use cookie negotiation mechanism to detect and resist memory-based denial-of-service (DoS) attack in the application layer. However, IKEv2 still cannot avoid IP fragment-based DoS attacks since the IKEv2 messages transmission runs over UDP and there are large IKE messages needed to be fragmented during the exchange process between two IKE peers. In this paper we first investigate some typical methods and give the analysis of their inability against the IP fragmentation DoS attack. To overcome this problem, we design a new IKEv2 header format called M-ISAKMP, and add a new type of Notification Payload and other related strategies. With the novel application-based fragmentation mechanism, our proposed enhanced IKEv2 protocol achieves defending against DoS attack successfully and efficiently.
The 3rd IEEE International Conference on Broadband Network& Multimedia Technology, Beijing, China; 10/2010
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ABSTRACT: We identified 17 polymorphisms in myostatin by sequencing, and three informative single nucleotide polymorphisms (SNPs) were selected for further observation for their association with peak BMD of women in 401 Chinese nuclear families. Our results suggest that genetic polymorphisms in myostatin likely play a role in attainment of peak BMD in Chinese women.
Myostatin is a TGF-beta family member that is a negative regulator of skeletal muscle growth.
We identified SNPs in myostatin by direct sequencing. Furthermore, using a quantitative transmission disequilibrium test (QTDT). we tested and further test whether SNPs were associated with peak bone mineral density (BMD) variation at the spines and hips of 401 Chinese nuclear families. We identified 17 polymorphisms in myostatin by sequencing. Next, we selected three informative SNPs for further observation of an association with peak BMD of premenopausal women in 401 Chinese nuclear families.
Using QTDT for the within-family association, we found significant association between rs2293284 and total hip, femoral neck, and trochanter BMD (all p < 0.05), while rs7570532 was associated with total hip and trochanter BMD (p = 0.034 and p = 0.035, respectively). The within-family association was significant between BMI and +2278G > A (p = 0.022). Subsequent permutations were in agreement with these significant within-family association results. Moreover, analyses of the haplotypes confer further evidence for association of rs2293284 and rs7570532 with hip peak BMD variation.
These results suggest, for the first time, the genetic polymorphisms in myostatin likely play a role in attainment of peak BMD in Chinese women.
Osteoporosis International 01/2008; 19(1):39-47. · 4.58 Impact Factor
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ABSTRACT: China has the largest population in the world; approximately 7% of the total population suffers from primary osteoporosis. Osteoporosis is mainly characterized by low bone mineral density (BMD). In the present study, familial correlation and segregation analyses for spine and hip BMDs have been undertaken for the first time in a Chinese sample composed of 401 nuclear families with a total of 1260 individuals. The results indicate a major gene of additive inheritance for hip BMD, whereas there is no evidence of a major gene influencing spine BMD. Significant familial residual effects are found for both traits, and heritability estimates (+/-SE) for spine and hip BMDs are 0.807(0.099) and 0.897(0.101), respectively. Sex and age differences in genotype-specific average BMD are also observed. This study provides the first evidence quantifying the high degree of genetic determination of BMD variation in the Chinese.
Annals of Human Genetics 04/2004; 68(Pt 2):154-64. · 2.57 Impact Factor
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ABSTRACT: In the present study, we simultaneously test linkage and/or association of the collagen type I alpha 2 (COL1A2) gene with bone mineral density (BMD) and bone area. A total of 1280 subjects from 407 Chinese nuclear families (including both parents and their daughters) were genotyped for an intragenic marker MspI in the COL1A2 gene. BMD and bone area at the lumbar spine and hip were measured by dual-energy X-ray absorptiometry. Applying the QTDT (quantitative transmission disequilibrium test) program, we performed tests for population stratification, within-family association (via transmission disequilibrium test), total association, linkage, and linkage while modeling association. Significant or marginal within-family associations were found with BMD at the lumbar spine (P = 0.013), trochanter (P = 0.004), and total hip (P = 0.053) and with bone area at the intertrochanteric region (P = 0.024) and total hip (P = 0.048). The positive associations were confirmed in permutations except for bone area at total hip (P > 0.10). A small proportion (<1%) of the population variance of bone phenotypes can be explained by the MspI polymorphism; however, it may be underestimated given the significant population stratification detected in our sample. Due to the limited number of sib pairs in this sample, we did not find evidence of linkage. In summary, the MspI polymorphism is likely to be in linkage disequilibrium with a nearby functional mutation affecting BMD and bone area.
Bone 11/2003; 33(4):614-9. · 4.02 Impact Factor
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ABSTRACT: Osteoporosis is an important health problem in the world. Alpha2-HS glycoprotein (AHSG) is involved in bone formation and metabolism and has been considered as an important candidate gene for osteoporosis. In this study, we simultaneously tested linkage and/or association of the AHSG gene with the variation of bone mineral density (BMD), an important risk factor for osteoporosis. A sample of 1,260 subjects from 401 Chinese nuclear families (including both parents and their daughters) were studied. The daughters' ages ranged from 20 to 45 years. All the subjects were genotyped by PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) at polymorphic Sac I site inside the exon 7 of the AHSG gene. This polymorphism involves a nucleotide substitution of C to G at the middle nucleotide of the codon at amino acid position 238, resulting in the replacement of threonine (ACC) with serine (AGC). BMD was measured at the lumbar spine and hip region by dual-energy X-ray absorptiometry (DXA). Using the QTDT (quantitative trait transmission disequilibrium test), we found no significant results for association or linkage between the AHSG gene and BMD variation at the spine or hip. Our data provided no evidence to support the AHSG gene as a quantitative trait locus (QTL) for the BMD variation in a Chinese population.
Calcified Tissue International 10/2003; 73(3):244-50. · 2.38 Impact Factor
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V Dvornyk,
X-H Liu,
H Shen,
S-F Lei,
L-J Zhao,
Q-R Huang, Y-J Qin,
D-K Jiang,
J-R Long,
Y-Y Zhang,
G Gong,
R R Recker,
H-W Deng
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ABSTRACT: Bone mineral density (BMD) is an important risk factor for osteoporosis and has strong genetic determination. While average BMD differs among major ethnic groups, several important candidate genes have been shown to underlie BMD variation within populations of the same ethnicity. To investigate whether important candidate genes may contribute to ethnic differences in BMD, we studied the degree of genetic differentiation among several important candidate genes between two major ethnic groups: Caucasians and Chinese. The genetic variability of these two populations (1131 randomly selected individuals) was studied at six restriction sites exhibiting polymorphisms of five important candidate genes for BMD: the BsaHI polymorphism of the calcium-sensing receptor (CASR) gene, the SacI polymorphism of the alpha2HS-glycoprotein (AHSG) gene, the PvuII and XbaI polymorphisms of the estrogen receptor alpha (ESR1) gene, the ApaI polymorphism of the vitamin D receptor (VDR) gene, and the BstBI polymorphism of the parathyroid hormone (PTH) gene. The two ethnic groups showed significant allelic and genotypic differentiation of all the polymorphisms studied. The mean FST was 0.103, which significantly differed from zero (P < 0.01). The Chinese population had lower mean heterozygosity (0.331) than the Caucasian one (0.444); the CASR-BsaHI and PTH-BstBI polymorphisms contributed most significantly to this difference. Analysis of the intra- and inter-population variability suggests that various types of natural selection may affect the observed patterns of variation at some loci. If some of the candidate genes we studied indeed underlie variation in BMD, their population differentiation revealed here between ethnic groups may contribute to understanding ethnic difference in BMD.
Annals of Human Genetics 05/2003; 67(Pt 3):216-27. · 2.57 Impact Factor
