Home About us Editorial board Ahead of print Current issue Search Archives Submit article Instructions Subscribe Contacts Login 


 
 Table of Contents  
ORIGINAL ARTICLE
Year : 2019  |  Volume : 15  |  Issue : 1  |  Page : 82-86

The association between survivin −31G>C polymorphism and susceptibility to sporadic colorectal cancer in a Southern Chinese population


1 Department of Gastrointestinal Surgery, The Second Affiliated Hospital of Nanchang University, Nanchang 330006; Department of Colorectal Surgery, The Sixth Affiliated Hospital of Sun Yat-Sen University, Guangzhou 510655, China
2 Department of Gastrointestinal Surgery, The Second Affiliated Hospital of Guangzhou Medical College, Guangzhou 510260, China
3 Department of Gastroenterology, The First Affiliated Hospital of Nanchang University, Nanchang 330006, China
4 Department of Colorectal Surgery, The Sixth Affiliated Hospital of Sun Yat-Sen University, Guangzhou 510655, China

Date of Web Publication13-Mar-2019

Correspondence Address:
Dr. Jianping Wang
Department of Colorectal Surgery, The Sixth Affiliated Hospital of Sun Yat-Sen University, 26 Yuancun Road, Guangzhou 510655
China
Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0973-1482.202894

Rights and Permissions
 > Abstract 


Background: The case–control study aimed to investigate the association between the −31G>C polymorphism in the promoter of survivin gene and the susceptibility to sporadic colorectal cancer (CRC) in a Southern Chinese population.
Materials and Methods: The study was carried out on 711 healthy controls and 702 CRC cases of a Southern Chinese population. Survivin gene −31G>C genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism. The association between CRC risk and −31G>C genetic polymorphism was estimated using an unconditional logistic regression model.
Results: The number of CC genotype carried in CRC patients was much higher than those of controls (P < 0.001). Compared with CC genotypes, GC, GG genotypes and −31G wild-type genotypes (i.e., GC + GG) had a significantly decreased risk of CRC (P < 0.001). In addition, survivin −31G wild-type genotypes were not associated with decreased risk of sporadic CRC patients with body mass index (BMI) ≥28.0 kg/m2, family cancer history, and premenopausal.
Conclusion: Survivin −31G>C polymorphism is associated with sporadic CRC risk in the Southern Chinese population. The −31G wild-type genotypes and GC, GG genotypes are the independent protective factors against sporadic CRC excluding those with a BMI ≥28.0 kg/m2, family cancer history, and premenopausal.

Keywords: Clinical research, colorectal cancer, genetic susceptibility, single nucleotide polymorphism, survivin


How to cite this article:
Huang J, Wei Y, Zhou X, Wang L, Huang M, Wang J. The association between survivin −31G>C polymorphism and susceptibility to sporadic colorectal cancer in a Southern Chinese population. J Can Res Ther 2019;15:82-6

How to cite this URL:
Huang J, Wei Y, Zhou X, Wang L, Huang M, Wang J. The association between survivin −31G>C polymorphism and susceptibility to sporadic colorectal cancer in a Southern Chinese population. J Can Res Ther [serial online] 2019 [cited 2019 Aug 22];15:82-6. Available from: http://www.cancerjournal.net/text.asp?2019/15/1/82/202894




 > Introduction Top


Colorectal cancer (CRC) is the fourth most common cancer worldwide for both of incidence and mortality.[1] It is the complex interaction between genetic and environmental factors that lead to the pathogenesis of CRC.[1],[2],[3]

Survivin is 16.5 kDa large and the smallest member of the inhibitor of apoptosis family of antiapoptotic proteins. It is encoded by human survivin gene, which is located on the 17q25 chromosome. Survivin is shown to be regulated at the transcriptional level according to the presence of cell cycle-dependent element/cell cycle gene homology region (CDE/CHR) boxes located in the survivin promoter region. The expression of survivin is known to be highly upregulated in most cancer cells including CRC, but it is rarely present in normal nonmalignant adult cells. It was demonstrated by Xiaoyuan et al. that the expression of survivin was an independent prognostic indicator of CRC.[2] However, the mechanism underlying this upregulation remains unclear. In the past, several studies have indicated that the increased expression of survivin might be closely related to the following mechanisms: (1) Proliferation of survivin gene;[4] (2) DNA demethylation or hypomethylation of its promoter (i.e., CpG islands);[5],[6],[7] (3) loss of wild-type p53;[8] (4) mutation or deletion of APC gene;[9] (5) a single nucleotide polymorphism (SNP) in the promoter element (i.e., core promoters, upstream promoters or enhancers), which might affect gene transcription by changing binding sites of transcription factors or affecting their binding kinetics.[10] Xu et al. first disclosed the significant association of the high expression of survivin with −31G>C polymorphism of CDE/CHR boxes in the promoter of survivin gene.[11] This polymorphism may affect the susceptibility to CRC through its influence on the expression of survivin. In the study, we conducted a multi-centered trial to investigate putative associations of −31G>C polymorphism with the susceptibility to develop sporadic CRC in a Southern Chinese population.


 > Materials and Methods Top


Study participants

From July 2002 to December 2008, 702 patients with CRC were recruited from six professional clinical centers located in the South China. All CRC patients were confirmed by histopathology. Criteria for CRC patients' eligibility were as follows: (1) Han Chinese; (2) permanent residents in Guangzhou and its surrounding areas; (3) no blood relationship with each other. Patients with familial adenomatous polyposis or hereditary nonpolyposis CRC were excluded. Over the same period, 711 matched healthy controls of Han Chinese by age (±5 years) and gender were enrolled from a subject pool who participated in health checkup programs in the same district. Baseline characteristics of enrolled participants were recorded including age, gender, height, weight, smoking habits, alcohol intake, family history of cancer, and menstrual history (female). Subjects were considered smoking only if they smoked at least 100 cigarettes/year. Those who drank alcohol at least once a week for more than 1 year were defined as consumers of alcohol. Besides, subjects were classified as low or normal weight if their body mass index (BMI) was ≤3.9 kg/m2, overweight if their BMI was 24.0–27.9 kg/m2, and obesity if the BMI was ≥28 kg/m2. Subjects were recorded with a family history of cancer if it was diagnosed in one first- or second-degree relative at least. After the one-on-one interview, 5-mL samples of venous blood were collected from each subject. This study was approved by the Institutional Review Board, and all participants gave written informed consent.

Genotyping

Genome DNA was extracted from peripheral blood of objects, using the QIAGEN DNA Isolation Kit (Qiagen, Valencia, CA, USA). Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methods were performed for genotyping survivin −31G>C (RefSNP ID: Rs9904341) in the promoter region of the human survivin gene. PCR was performed with 12 μL of reaction mixture that was initially predenatured at 94°C for 5 min, then denatured at 94°C for 30 s, followed by 35 cycles of 45 s at annealing temperature and 15 s for extension at 72°C, and a final extension of 10 min at 72°C. Suitable primers were used to amplify the corresponding PCR products, and restriction products were digested by Msp I (New England BioLabs). Restriction DNA products were separated by 2% agarose gel electrophoresis and visualized by ultraviolet light. In addition, 10% of randomly selected samples were further sequenced to verify the accuracy of the genotyping results of PCR-RFLP.

Statistical analysis

All statistical analyses were performed using SPSS 13.0 (SPSS Inc, Chicago, IL, USA) software. Pearson's Chi-square test was used to compare the differences in gender, age, smoking, alcohol intake, BMI, family history of cancer, menstrual history, genotype, and allele frequency at survivin −31G>C between CRC patients and control groups. A goodness-of-fit Chi-square test was used for testing the Hardy–Weinberg genetic equilibrium. Besides, the correlation between survivin −31G>C and CRC susceptibility was analyzed using a nonconditional logistic regression model. Gender, age, smoking, alcohol intake, BMI, family history of cancer, and other factors were also included in a multivariate logistic regression model to correct and estimate relative risks of the SNPs tested on the incidence of CRC by adjusted odds ratio (OR) and a 95% confidence interval (CI). All statistical tests were two-tailed, and P < 0.05 was considered statistically significant.


 > Results Top


Demographics of the enrolled subjects

The distribution of demographic parameters between CRC patients and controls is shown in [Table 1]. No significant differences were found between patients and control subjects in terms of age, gender, and menstrual history (P > 0.05), suggesting that the frequency matching was adequate. However, the frequencies of smoking, alcohol intake, high BMI, and family history of cancer were found to be significantly higher in the CRC group than that of the control group (P < 0.05) [Table 1]. Nonconditional logistic regression analysis showed that smoking was not associated with CRC, while the associations of both alcohol intake and family history of cancer with CRC were significant (P < 0.05) [Table 1].
Table 1: Frequencies of confounding factors and distribution of demographic characteristics in CRC patients and controls

Click here to view


Association of single nucleotide polymorphism with susceptibility to sporadic colorectal cancer

From the analyzed results of genome DNA, Msp I restriction map of survivin gene −31G>C polymorphism was shown [Supplementary Figure 1]a. The SNPs derived from PCR-RFLP were further validated by sequence in 10% of randomly selected samples [Supplementary Figure 1]b. Distributions of the genotypes' frequencies of the polymorphism among patients and controls are shown in [Table 2]. In the control group, the genotype distribution frequency of −31G>C in the survivin gene promoter was found to be consistent with a Hardy-Weinberg genetic equilibrium (χ2 = 0.62, P = 0.43), indicating that there were no differences in genetic background between the CRC patient and controls. Besides, the frequency rates of −31C variant alleles and CC genotype in CRC group were significantly higher than those of control group (58.0% vs. 50.4%, χ2 = 16.24, P < 0.001; 36.5% vs. 26.2%, χ2 = 17.89, P < 0.001). Nonconditional logistic regression analysis showed that compared to individuals carrying the variant homozygous genotype CC, those with GC, GG, and wild-type −31G (GC + GG) exhibited a 39% (95% CI = 0.46–0.80, P < 0.001), 48% (95% CI = 0.38–0.71, P < 0.001), and 42% (95% CI = 0.45–0.74, P < 0.001) lower risk of developing CRC, respectively. Compared to those carrying the variant allele C, individuals with allele G exhibited a 31% (95% CI = 0.59–0.82, P < 0.001) lower risk for developing CRC [Table 2].

Table 2: Distribution of genotypes and alleles of surviving -31G>C between CRC patients and controls

Click here to view


Stratification analysis of single nucleotide polymorphism and colorectal cancer risk

To evaluate the effects of survivin −31G>C genotypes on the risk of CRC, patients and controls were stratified based on age, sex, smoking status, drinking status, family history of cancer, and BMI [Table 3]. According to the correction analysis for confounding factors, it was found that those with wild-type −31G (GC + GG) exhibited a significantly decreased risk of CRC for all ages (adjusted OR = 0.58, 95% CI = 0.34–1.00; adjusted OR = 0.47, 95% CI = 0.28–0.78; adjusted OR = 0.61, 95% CI = 0.43–0.87), both for men (95% CI = 0.43–0.85) and women (95% CI = 0.43–0.87) compared to carriers of variant homozygous CC alleles. Besides, either drinking or not, those with wild-type −31G (GC + GG) exhibited a significantly decreased risk of CRC compared with carriers of CC alleles (adjusted OR = 0.61, 95% CI = 0.42–0.81; adjusted OR = 0.59, 95% CI = 0.39–0.90). However, the wild-type −31G (GC + GG) was not significantly protective against CRC in those with family history of cancer (adjusted OR = 0.69, 95% CI = 0.36–1.31, P = 0.765), high BMI (≥28.0 kg/m2) (adjusted OR = 0.68, 95% CI = 0.24–1.96, P = 0.67), and nonmenopause (adjusted OR = 0.55, 95% CI = 0.23–1.34, P = 0.187) [Table 3]. In addition, the results of stratified analyses of colon cancer and rectal cancer were in accordance with those of CRC except that wild-type −31G (GC + GG) was not significantly associated with the decreased risk of colon cancer (adjusted OR = 0.65, 95% CI = 0.41–1.03, P = 0.066) when compared with the variant homozygous CC alleles [Supplementary Table 1], [Supplementary Table 2], [Supplementary Table 3], [Supplementary Table 4].
Table 3: Stratified analysis of the genotype frequencies of -31G>C between CRC patients and controls

Click here to view




 > Discussion Top


The −31G>C polymorphism of CDE/CHR boxes in the promoter was found to be significantly associated with the high expression of survivin gene, and this regulation was proved to be at the transcriptional level. Thus, we deduced that the regulation of the expression of survivin gene by this SNP might affect the susceptibility to sporadic CRC. In our study, 702 CRC patients and 711 matched controls in South China were enrolled over the same period. The frequency rates of −31C variant alleles and CC genotype in CRC patients were significantly higher than those control group. Compared to individuals carrying the variant homozygous genotype CC, those with GC, GG, and wild-type −31G (GC + GG) exhibited decreased risk of developing CRC. Individuals carrying allele G also exhibited lower risk for developing CRC when compared with those carrying the variant allele C. Wild-type −31G (GC + GG), GC and GG genotypes might promote the binding of the repressor with CDE/CHR boxes and inhibited the transcription of survivin promoter. These findings confirm with the previous researches of the previous studies[12],[13],[14] that documented −31G/C polymorphism, −31CC and −31C were associated with increased risk of CRC. Besides, Xu et al.[11] have reported that the presence of the −31G/C polymorphism was more frequent in malignant cell lines with increased survivin expression at both mRNA and protein levels. In addition, in a Gaozouli et al.'s[14] study, they have observed that in cancer cases, the survivin mRNA in the samples homozygous for −31CC genotype was approximately 1.6-fold higher than the carriers of the −31GG and −31GC genotypes. Survivin plays a role as the antagonist of apoptotic cell death and functions at the regulation of mitosis.[15],[16] Thus, the overexpression of survivin relates closely to the increase of invasion and metastasis of CRC.[17] However, the mechanism underlying the overexpression of survivin in cases with −31CC genotype remains unknown.[14] As a result, the expression of survivin was downregulated and apoptosis increased. Therefore, the susceptibility to CRC of these genotypes decreased.

In the study, a stratified analysis of subgroups showed that when in those with BMI ≥28.0 kg/m2, family history of cancer, and nonmenopause, wild-type −31G (GC + GG), GC and GG genotypes were not significantly associated with the decreased risk of CRC. A variety of previous studies suggested that obesity, as an independent risk factor of CRC, could significantly increase the susceptibility to CRC.[17],[18],[19] Usually, obesity is accompanied by certain metabolism disorders such as insulin resistance, hyperinsulinism, increased IGF-1, decreased adiponectin, and IGFBP-3. These issues were proved to be closely related to the incidence of CRC.[20],[21],[22],[23] Besides, wild-type −31G was no longer protective in those with a family history of cancer, which might be due to the change of whole genetic background. Epidemiological surveys validated that estrogen and progesterone could decrease the risk of CRC,[24],[25],[26] which might result from the inhibition of the CRC differentiation by estrogen and its receptors and led to cell cycle arrest and apoptosis.[27],[28] Hence, we suspect that obesity, family history of cancer, and estrogen could resist the protection effect of wild-type −31G (GC + GG) against CRC in the Southern Chinese population.

In the stratified analysis of colon cancer, there were no significant associations between wild-type survivin −31G and decreased susceptibility to sporadic CRC. As is known, cigarette produces more than sixty types of carcinogens, including polycyclic aromatic hydrocarbons, heterocyclic amines, nitrosamine, and benzopyrene.[29] These carcinogens can reach colorectal tissues through the circulatory system without a direct effect on colon and rectum.[30] It has been shown that benzopyrene-DNA adducts could be detected more frequently in colorectal mucosa cells of smokers than that of nonsmokers, thus increasing the risk of CRC.[31] Therefore, the synergistic effects of smoking and survivin −31G>C polymorphism may weaken the protection of wild-type −31G genotypes against sporadic CRC. Several limitations of this case–control study need addressing. The sample size was not determined by power calculations, which might affect the accuracy of the results. Besides, an SNP may only have a modest effect. More studies focusing on the combined effects of multiple variants will help estimate the genetic factors of sporadic CRC comprehensively.


 > Conclusion Top


Survivin −31G>C polymorphism is associated with genetic susceptibility to sporadic CRC in a Southern Chinese population. Wild-type survivin −31G (GC + GG) and GC and GG genotypes are independent protective factors against sporadic CRC. However, this protective effect is not significant in those with BMI ≥28.0 kg/m2, family history of cancer, and nonmenopause.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
 > References Top

1.
Siegel R, Desantis C, Jemal A. Colorectal cancer statistics, 2014. CA Cancer J Clin 2014;64:104-17.  Back to cited text no. 1
    
2.
Xiaoyuan C, Longbang C, Jinghua W, Xiaoxiang G, Huaicheng G, Qun Z, et al. Survivin: A potential prognostic marker and chemoradiotherapeutic target for colorectal cancer. Ir J Med Sci 2010;179:327-35.  Back to cited text no. 2
    
3.
Ma W, Yu J, Qi X, Liang L, Zhang Y, Ding Y, et al. Radiation-induced microRNA-622 causes radioresistance in colorectal cancer cells by down-regulating Rb. Oncotarget 2015;6:15984-94.  Back to cited text no. 3
    
4.
Islam A, Kageyama H, Takada N, Kawamoto T, Takayasu H, Isogai E, et al. High expression of Survivin, mapped to 17q25, is significantly associated with poor prognostic factors and promotes cell survival in human neuroblastoma. Oncogene 2000;19:617-23.  Back to cited text no. 4
    
5.
Hattori M, Sakamoto H, Satoh K, Yamamoto T. DNA demethylase is expressed in ovarian cancers and the expression correlates with demethylation of CpG sites in the promoter region of c-erbB-2 and survivin genes. Cancer Lett 2001;169:155-64.  Back to cited text no. 5
    
6.
Tanaka C, Uzawa K, Shibahara T, Yokoe H, Noma H, Tanzawa H. Expression of an inhibitor of apoptosis, survivin, in oral carcinogenesis. J Dent Res 2003;82:607-11.  Back to cited text no. 6
    
7.
Gao L, Qi X, Hu K, Zhu R, Xu W, Sun S, et al. Estrogen receptor ß promoter methylation: A potential indicator of malignant changes in breast cancer. Arch Med Sci 2016;12:129-36.  Back to cited text no. 7
    
8.
Hoffman WH, Biade S, Zilfou JT, Chen J, Murphy M. Transcriptional repression of the anti-apoptotic survivin gene by wild type p53. J Biol Chem 2002;277:3247-57.  Back to cited text no. 8
    
9.
Zhang T, Otevrel T, Gao Z, Gao Z, Ehrlich SM, Fields JZ, et al. Evidence that APC regulates survivin expression: A possible mechanism contributing to the stem cell origin of colon cancer. Cancer Res 2001;61:8664-7.  Back to cited text no. 9
    
10.
Bessenyei B, Márka M, Urbán L, Zeher M, Semsei I. Single nucleotide polymorphisms: Aging and diseases. Biogerontology 2004;5:291-303.  Back to cited text no. 10
    
11.
Xu Y, Fang F, Ludewig G, Jones G, Jones D. A mutation found in the promoter region of the human survivin gene is correlated to overexpression of survivin in cancer cells. DNA Cell Biol 2004;23:527-37.  Back to cited text no. 11
    
12.
Huang J, Wang JP, Wang L, Liu HL, Wei YS, Huang MJ, et al. Association between survivin promoter -31G/C polymorphism and genetic susceptibility to sporadic colorectal cancer. Chin J Pathophysiol 2009;25:2344-8.  Back to cited text no. 12
    
13.
Jang JS, Kim KM, Kang KH, Choi JE, Lee WK, Kim CH, et al. Polymorphisms in the survivin gene and the risk of lung cancer. Lung Cancer 2008;60:31-9.  Back to cited text no. 13
    
14.
Gazouli M, Tzanakis N, Rallis G, Theodoropoulos G, Papaconstantinou I, Kostakis A, et al. Survivin -31G/C promoter polymorphism and sporadic colorectal cancer. Int J Colorectal Dis 2009;24:145-50.  Back to cited text no. 14
    
15.
Skoufias DA, Mollinari C, Lacroix FB, Margolis RL. Human survivin is a kinetochore-associated passenger protein. J Cell Biol 2000;151:1575-82.  Back to cited text no. 15
    
16.
Dohi T, Okada K, Xia F, Wilford CE, Samuel T, Welsh K, et al. An IAP-IAP complex inhibits apoptosis. J Biol Chem 2004;279:34087-90.  Back to cited text no. 16
    
17.
Siegel EM, Ulrich CM, Poole EM, Holmes RS, Jacobsen PB, Shibata D. The effects of obesity and obesity-related conditions on colorectal cancer prognosis. Cancer Control 2010;17:52-7.  Back to cited text no. 17
    
18.
Singh-Ranger G. Comment on: Visceral obesity may affect oncologic outcome in patients with colorectal cancer. Ann Surg Oncol 2010;17:348.  Back to cited text no. 18
    
19.
Burke CA. Colonic complications of obesity. Gastroenterol Clin North Am 2010;39:47-55.  Back to cited text no. 19
    
20.
Pais R, Silaghi H, Silaghi AC, Rusu ML, Dumitrascu DL. Metabolic syndrome and risk of subsequent colorectal cancer. World J Gastroenterol 2009;15:5141-8.  Back to cited text no. 20
    
21.
Gonullu G, Kahraman H, Bedir A, Bektas A, Yücel I. Association between adiponectin, resistin, insulin resistance, and colorectal tumors. Int J Colorectal Dis 2010;25:205-12.  Back to cited text no. 21
    
22.
Yamamoto S, Nakagawa T, Matsushita Y, Kusano S, Hayashi T, Irokawa M, et al. Visceral fat area and markers of insulin resistance in relation to colorectal neoplasia. Diabetes Care 2010;33:184-9.  Back to cited text no. 22
    
23.
Kang HW, Kim D, Kim HJ, Kim CH, Kim YS, Park MJ, et al. Visceral obesity and insulin resistance as risk factors for colorectal adenoma: A cross-sectional, case-control study. Am J Gastroenterol 2010;105:178-87.  Back to cited text no. 23
    
24.
Hildebrand JS, Jacobs EJ, Campbell PT, McCullough ML, Teras LR, Thun MJ, et al. Colorectal cancer incidence and postmenopausal hormone use by type, recency, and duration in cancer prevention study II. Cancer Epidemiol Biomarkers Prev 2009;18:2835-41.  Back to cited text no. 24
    
25.
Rennert G, Rennert HS, Pinchev M, Lavie O, Gruber SB. Use of hormone replacement therapy and the risk of colorectal cancer. J Clin Oncol 2009;27:4542-7.  Back to cited text no. 25
    
26.
Hoffmeister M, Raum E, Krtschil A, Chang-Claude J, Brenner H. No evidence for variation in colorectal cancer risk associated with different types of postmenopausal hormone therapy. Clin Pharmacol Ther 2009;86:416-24.  Back to cited text no. 26
    
27.
Hartman J, Edvardsson K, Lindberg K, Zhao C, Williams C, Ström A, et al. Tumor repressive functions of estrogen receptor beta in SW480 colon cancer cells. Cancer Res 2009;69:6100-6.  Back to cited text no. 27
    
28.
Wei Z, Ma W, Qi X, Zhu X, Wang Y, Xu Z, et al. Pinin facilitated proliferation and metastasis of colorectal cancer through activating EGFR/ERK signaling pathway. Oncotarget 2016;7:29429-39.  Back to cited text no. 28
    
29.
Hoffmann D, Hoffmann I, El-Bayoumy K. The less harmful cigarette: A controversial issue. A tribute to Ernst L. Wynder. Chem Res Toxicol 2001;14:767-90.  Back to cited text no. 29
    
30.
Raimondi S, Botteri E, Iodice S, Lowenfels AB, Maisonneuve P. Gene-smoking interaction on colorectal adenoma and cancer risk: Review and meta-analysis. Mutat Res 2009;670:6-14.  Back to cited text no. 30
    
31.
Pfohl-Leszkowicz A, Grosse Y, Carrière V, Cugnenc PH, Berger A, Carnot F, et al. High levels of DNA adducts in human colon are associated with colorectal cancer. Cancer Res 1995;55:5611-6.  Back to cited text no. 31
    



 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

Top
 
 
  Search
 
Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
Access Statistics
Email Alert *
Add to My List *
* Registration required (free)

  >Abstract>IntroductionMaterials and Me...>Results>Discussion>Conclusion>Article Tables
  In this article
>References

 Article Access Statistics
    Viewed1016    
    Printed56    
    Emailed0    
    PDF Downloaded48    
    Comments [Add]    

Recommend this journal


[TAG2]
[TAG3]
[TAG4]