Startseite Biological pathway selection through Bayesian integrative modeling
Artikel
Lizenziert
Nicht lizenziert Erfordert eine Authentifizierung

Biological pathway selection through Bayesian integrative modeling

Ein Erratum zu diesem Artikel finden Sie hier: https://doi.org/10.1515/sagmb-2014-0087
  • Lingling Zheng EMAIL logo , Xiao Yan , Sunil Suchindran , Holly Dressman , John P. Chute und Joseph Lucas
Veröffentlicht/Copyright: 17. Juni 2014

Abstract

Pathway analysis has become a central approach to understanding the underlying biology of differentially expressed genes. As large amounts of microarray data have been accumulated in public repositories, flexible methodologies are needed to extend the analysis of simple case-control studies in order to place them in context with the vast quantities of available and highly heterogeneous data sets. To address this challenge, we have developed a two-level model, consisting of 1) a joint Bayesian factor model that integrates multiple microarray experiments and ties each factor to a predefined pathway and 2) a point mass mixture distribution that infers which factors are relevant/irrelevant to each dataset. Our method can identify pathways specific to a particular experimental trait which are concurrently induced/repressed under a variety of interventions. In this paper, we describe the model in depth and provide examples of its utility in simulations as well as real data from a study of radiation exposure. Our analysis of the radiation study leads to novel insights into the molecular basis of time- and dose- dependent response to ionizing radiation in mice peripheral blood. This broadly applicable model provides a starting point for generating specific and testable hypotheses in a pathway-centric manner.


Corresponding author: Lingling Zheng, Duke Univeristy – Computational Biology and Bioinformatics, Durham, North Carolina 27708, USA, Tel.: 91 944 85 862, e-mail: ;

  1. 1

    The sparsity constant τ0 refers to the percentage of binary numbers in the pathway selection matrix γ.

  2. 2

    As opposed to “partial pathways,” “intact pathways” refer to those the entire gene set of which is activated/repressed under a particular experimental perturbation.

Acknowledgments

The authors thank three anonymous reviewers and associate editor for their careful reading and constructive comments. This work was supported by funding from the grant “R01 DK089705” and Biomedical Advanced Research and Development Authority (BARDA). The research and results contained in this article are the contributions of the authors and should not be interpreted as representing the official views or policies, either expressed or implied, of the sponsor.

Appendices

  • updated distribution for loadings βFor factor k, let xg,d,j*=xg,d,jμg,dlkβg,lfl,d,j, so that xg,d,j~N(βg,kfk,d,j,θg,d). Therefore, Pr(βg,k|zg,k=1,)d=1Dj=1NdN(xg,d,j*|βg,kfk,d,j,θg,d)N(βg,k|mg,k,ϕg,k)d=1Dj=1Ndexp((xg,d,j*βg,kfk,d,j)22θg,d)exp((βg,kmg,k)22ϕg,k)exp(βg,k22(djfk,d,j2θg,d+1ϕg,k)+βg,k(djxg,d,j*fk,d,jθg,d+mg,kϕg,k))~N(ηβ,υβ) where υβ=1/(djfk,d,j2θg,d+1ϕg,k),ηβ=υβ(djxg,d,j*fk,d,jθg,d+mg,kϕg,k).if zg, k=0, then βg, k=0.

  • updated distribution for mg, kPr(mg,k|)N(βg,k|mg,k,ϕg,k)N(mg,k;u0,n0)exp((βg,kmg,k)22ϕg,k)exp((mg,ku0)22n0)~N(um,nm) where nm=1/(1n0+1ϕg,k),um=nm(u0n0+βg,kϕg,k).u0 and n0 are respectively the prior mean and variance.

  • updated distribution for φg, kPr(ϕg,k|)N(βg,k|mg,k,ϕg,k)Ga(ϕg,k1;c0,d0)exp((βg,kmg,k)22ϕg,k)ϕg,k0.5ϕg,k(c01)exp(d0ϕg,k)~Ga(ϕg,k1;cϕ,dϕ) where cφ=c0+0.5, dφ=d0+0.5×(βg, kmg, k)2. c0 and d0 are the prior shape and rate parameters of the gamma distribution, respectively.

  • updated distribution for factor scores Ffk, d, j=0 if γk, d,· =0, otherwise Pr(fk,d,j|γk,d,=1,)Pr(xd,j|fk,d,j,)Pr(fk,d,j|yk,d,j,γk,d,)N(xd,j*;βkfk,d,j,θd)N(fk,d,j;0,1)exp(0.5×(xd,j*βkfk,d,j)Tθd1(xd,j*βkfk,d,j))exp(fk,d,j22)N(fk,d,j;ηf,υf) where υf=1/(1+βkTθd1βk),ηf=υf×βkTθd1xd,j*.

  • updated distribution for γk, d, Pr(γk,d,|)jPr(xd,j|γk,d,,yk,d,j,)Pr(yk,d,j|γk,d,)Pr(γk,d,|πk)dyk,d,j=jN(xd,j*;βkγk,d,yk,d,j,θd)N(yk,d,j;0,1)((1πk)δ0+πkδ1)dyk,d,j=(1πk)δ0jN(xd,j*;0,θd)+πkj|θd|122πexp(0.5×(xd,j*βkyk,d,j)Tθd1(xd,j*βkyk,d,j))12πexp(yk,d,j22)dyk,d,j(1πk)δ0+πkj12πexp(0.5×(yk,d,j2(βkTθd1βk+1)2×yk,d,jβkTθd1xd,j*))dyk,d,j=(1πk)δ0+πk(Vk,d)Ndexp(jMk,d,j22Vk,d)jexp((yk,d,jMk,d,j)22Vk,d)12πVk,ddyk,d,j where Vk, d=υf, Mk, d, j=ηf. Therefore, sampling γk, d,· =1 with posterior odds π^k1π^k=πk1πk(Vk,d)Ndexp(jMk,d,j22Vk,d) Otherwise, γk, d,· =0

  • updated distribution for πkPr(πk|)djPr(γk,d,|πk)Pr(πk|ρ)=(1πk)NSπkS(((ρ)Beta(α0,κ0)+ρBeta(κ0,α0))(1πk)NSπkS(1ρ)πkα01(1πk)κ01+(1πk)NSπkSρπkκ01(1πk)α01=(1ρ)Beta(πk;S+α0,NS+κ0)B(S+α0,NS+κ0)+ρBeta(πk;S+κ0,NS+α0)B(S+κ0,NS+α0) Where SdΣjI(γk, d,· =1), N is the total sample size. Therefore, sampling πk from Beta(πk; S+κ0, NS+α0) with posterior oddsρ^1ρ^=ρ1ρB(S+κ0,NS+α0)B(S+α0,NS+κ0) Otherwise, πk is sampled from Beta(πk; S+α0, NS+κ0κ0 and α0 are the prior shape parameters of the beta distribution.

  • updated distribution for ρPr(ρ|)kPr(πk|ρ)Pr(ρ)=(1ρ)KQρQBeta(e0,l0)(1ρ)KQρQρe01(1ρ)l01~Beta(ρ;Q+e0,KQ+l0) where Q is the number of times πk is sampled from Beta(πk;S+κ0, NS+α0). e0 and l0 are the shape parameters of the beta distribution.

  • updated distribution for noise variance θPr(θg,d|)jN(xg,d,jμg,d;βgfd,j,θg,d)Ga(θg,d1;a0,b0)exp(0.5×j=1Nd(xg,d,jμg,dβgfd,j)2θg,d)θg,dNd2θg,d(a01)exp(b0θg,d)~Ga(θg,d1;aθ,bθ) where aθ=a0+Nd2,bθ=b0+j=1Nd(xg,d,jμg,dβgfd,j)22.a0 and b0 are the prior shape and rate parameters of the gamma distribution, respectively.

  • updated distribution for sample mean μPr(μg,d|)jN(xg,d,jμg,d;βgfd,j,θg,d)N(μg,d;m0,s0)exp(0.5×j=1Nd(xg,d,jμg,dβgfd,j)2θg,d)exp((μg,dm0)22s0)~N(μg,d;mμ,sμ) where sμ=1/(1s0+Ndθd),mμ=sμ×(m0s0+θg,d1×j=1Nd(xg,d,jβgfd,j)).m0 and s0 are respectively prior mean and variance parameters.

References

Beier, U. H., L. Wang, T. R. Bhatti, Y. Liu, R. Han, G. Ge and W. W. Hancock (2011): “Sirtuin-1 targeting promotes Foxp3+T-regulatory cell function and prolongs allograft survival,” Mole. Cell. Biol., 31, 1022–1029.Suche in Google Scholar

Bhattacharya, A. and D. B. Dunson (2011): “Sparse Bayesian infinite factor models,” Biometrika, 98, 291–306.10.1093/biomet/asr013Suche in Google Scholar

Buxant, F., D. Bucella, V. Anaf, P. Simon and J.C. Noël (2009): “Glucocorticoid receptor expression in cervical intraepithelial neoplasia and invasive squamous cell carcinoma of the cervix,” Eur. J. Gynaecol. Oncol., 30, 259–262.Suche in Google Scholar

Chung, E. and M. Kondo (2011): “Role of Ras/Raf/MEK/ERK signaling in physiological hematopoiesis and leukemia development,” Immunol. Res., 49, 248–268.Suche in Google Scholar

Congdon, K. L., C. Voermans, E. C. Ferguson, L. N. DiMascio, M. Uqoezwa, C. Zhao and T. Reya (2008): “Activation of Wnt signaling in hematopoietic regeneration,” Stem Cells, 26, 1202–1210.10.1634/stemcells.2007-0768Suche in Google Scholar

De Zoeten, E. F., L. Wang, K. Butler, U. H. Beier, T. Akimova, H. Sai, J. E. Bradner, R. Mazitschek, A. P. Kozikowski, P. Matthias and W. W. Hancock (2011): “Histone deacetylase 6 and heat shock protein 90 control the functions of Foxp3+ T-regulatory cells,” Mole. Cell. Biol., 31, 2066–2078.Suche in Google Scholar

Dennis, G., B. Sherman, D. Hosack, J. Yang, W. Gao, H. C. Lane and R. Lempicki (2003): “David: database for annotation, visualization, and integrated discovery,” Genome Biol., 4, P3.Suche in Google Scholar

Edgar, R., M. Domrachev and A. E. Lash (2002): “Gene expression omnibus: NCBI gene expression and hybridization array data repository,” Nucleic Acids Res., 30, 207–210.Suche in Google Scholar

Gentile, M., L. Latonen and M. Laiho (2003): “Cell cycle arrest and apoptosis provoked by UV radiation-induced DNA damage are transcriptionally highly divergent responses,” Nucleic Acids Res., 31, 4779–4790.Suche in Google Scholar

Georgantas, R. W., V. Tanadve, M. Malehorn, S. Heimfeld, C. Chen, L. Carr, F. Martinez-Murillo, G. Riggins, J. Kowalski and C. I. Civin (2004): “Microarray and serial analysis of gene expression analyses identify known and novel transcripts overexpressed in hematopoietic stem cells,” Cancer Res., 64, 4434–4441.Suche in Google Scholar

Gerber, H. -P. and N. Ferrara (2003): “The role of VEGF in normal and neoplastic hematopoiesis,” J. Mole. Med., 81, 20–31.Suche in Google Scholar

Gower, A., A. Spira and M. Lenburg (2011): “Discovering biological connections between experimental conditions based on common patterns of differential gene expression,” BMC Bioinformatics, 12, 381–395.10.1186/1471-2105-12-381Suche in Google Scholar

Habermehl, D., J. R. Parkitna, S. Kaden, B. Brgger, F. Wieland, H. -J. Gršne and G. Schtz (2011): “Glucocorticoid activity during lung maturation is essential in mesenchymal and less in alveolar epithelial cells,” Mole. Endocrinol., 25, 1280–1288.Suche in Google Scholar

Han, D., M. Zhang, J. Ma, J. Hong, C. Chen, B. Zhang, L. Huang, W. Lv, L. Yin, A. Zhang, H. Zhang, Z. Zhang, S. Vidyasagar, P. Okunieff and L. Zhang (2012): “Transition pattern and mechanism of B-lymphocyte precursors in regenerated mouse bone marrow after subtotal body irradiation,” PLoS ONE, 7, e46560.10.1371/journal.pone.0046560Suche in Google Scholar

Hanzelmann, S., R. Castelo and J. Guinney (2013): “GSVA: gene set variation analysis for microarray and RNA-Seq data,” BMC Bioinformatics, 14, 7–21.10.1186/1471-2105-14-7Suche in Google Scholar

Henao, R., J. W. Thompson, M. A. Moseley, G. S. Ginsburg, L. Carin and J. E. Lucas (2013): “Latent protein trees,” Ann. Appl. Stat., 7, 691–713.Suche in Google Scholar

Hosack, D., G. Dennis, B. Sherman, H. Lane and R. Lempicki (2003): “Identifying biological themes within lists of genes with ease,” Genome Biol., 4, R70.Suche in Google Scholar

Huang, D. W., B. T. Sherman and R. A. Lempicki (2009a): “Bioinformatics enrichment tools: paths toward the comprehensive functional analysis of large gene lists,” Nucleic Acids Res., 37, 1–13.10.1093/nar/gkn923Suche in Google Scholar

Huang, J., Y. Zhang, A. Bersenev, W. T. OBrien, W. Tong, S. G. Emerson and P. S. Klein (2009b): “Pivotal role for glycogen synthase kinase3 in hematopoietic stem cell homeostasis in mice,” J. Clin. Invest., 119, 3519–3529.10.1172/JCI40572Suche in Google Scholar

Hughes, T. R., M. J. Marton, A. R. Jones, C. J. Roberts, R. Stoughton, C. D. Armour, H. A. Bennett, E. Coffey, H. Dai, Y. D. He, M. J. Kidd, A. M. King, M. R. Meyer, D. Slade, P. Y. Lum, S. B. Stepaniants, D. D. Shoemaker, D. Gachotte, K. Chakraburtty, J. Simon, M. Bard and S. H. Friend (2000): “Functional discovery via a compendium of expression profiles,” Cell, 102, 109–126.10.1016/S0092-8674(00)00015-5Suche in Google Scholar

Jaffe, I. Z., B. G. Newfell, M. Aronovitz, N. N. Mohammad, A. P. McGraw, R. E. Perreault, P. Carmeliet, A. Ehsan and M. E. Mendelsohn (2010): “Placental growth factor mediates aldosterone-dependent vascular injury in mice,” J. Clin. Inves., 120, 3891–3900.Suche in Google Scholar

Kanehisa, M. and S. Goto (2000): “KEGG: Kyoto Encyclopedia of Genes and Genomes,” Nucleic Acids Res., 28, 27–30.Suche in Google Scholar

Karpov, A., Y. Semenova, R. Takhauov, T. Litvinenko and D. Kalinkin (2012): “The risk of acute myocardial infarction and arterial hypertension in a cohort of male employees of a siberian group of chemical enterprises exposed to long-term irradiation,” Health Phys., 103, 15–23.10.1097/HP.0b013e318249fa59Suche in Google Scholar PubMed

Kim, M. -S., Y. Kim, D. Lee, J. Seo, K. Cho, H. Eun and J. Chung (2009): “Acute exposure of human skin to ultraviolet or infrared radiation or heat stimuli increases mast cell numbers and tryptase expression in human skin in vivo,” Brit. J. Dermatol., 160, 393–402.10.1111/j.1365-2133.2008.08838.xSuche in Google Scholar PubMed

Lee, M. S., K. Hanspers, C. S. Barker, A. P. Korn and J. M. McCune (2004): “Gene expression profiles during human CD4+ T cell differentiation,” Int. Immunol., 16, 1109–1124.Suche in Google Scholar

Liberzon, A., A. Subramanian, R. Pinchback, H. Thorvaldsdttir, P. Tamayo and J. P. Mesirov (2011): “Molecular signatures database (MSigDB) 3.0,” Bioinformatics, 27, 1739–1740.10.1093/bioinformatics/btr260Suche in Google Scholar PubMed PubMed Central

Lucas, J., C. Carvalho, Q. Wang, A. Bild, J. Nevins and M. West (2006): “Sparse statistical modelling in gene expression genomics,” In: Müller P., K. Do, M. Vannucci, editors. Bayesian Inference for Gene Expression and Proteomics. Cambridge, U.K.: Cambridge University Press, 155–176.10.1017/CBO9780511584589.009Suche in Google Scholar

Lucas, J., C. Carvalho and M. West (2009): “A Bayesian analysis strategy for cross-study translation of gene expression biomarkers,” Stat. Appl. Genet. Mole. Biol., 8, 1–26.Suche in Google Scholar

Lucas, J. E., H. -N. Kung and J. -T. A. Chi (2010): “Latent factor analysis to discover pathway-associated putative segmental aneuploidies in human cancers,” PLoS Comput. Biol., 6, e1000920.Suche in Google Scholar

McCubrey, J. A., L. S. Steelman, S. L. Abrams, F. E. Bertrand, D. E. Ludwig, J. Basecke, M. Libra, F. Stivala, M. Milella, A. Tafuri, P. Lunghi, A. Bonati and A. M. Martelli (2008): “Targeting survival cascades induced by activation of Ras/Raf/MEK/ERK, PI3K/PTEN/Akt/mTOR and Jak/STAT pathways for effective leukemia therapy,” Leukemia, 22, 708–722.10.1038/leu.2008.27Suche in Google Scholar PubMed

Mihailidou, A. S., T. Y. Loan Le, M. Mardini and J. W. Funder (2009): “Glucocorticoids activate cardiac mineralocorticoid receptors during experimental myocardial infarction,” Hypertension, 54, 1306–1312.10.1161/HYPERTENSIONAHA.109.136242Suche in Google Scholar PubMed

Nakajima, T., K. Matsumoto, H. Suto, K. Tanaka, M. Ebisawa, H. Tomita, K. Yuki, T. Katsunuma, A. Akasawa, R. Hashida, Y. Sugita, H. Ogawa, C. Ra and H. Saito (2001): “Gene expression screening of human mast cells and eosinophils using high-density oligonucleotide probe arrays: abundant expression of major basic protein in mast cells,” Blood, 98, 1127–1134.10.1182/blood.V98.4.1127Suche in Google Scholar

Nouzova, M., N. Holtan, M. M. Oshiro, R. B. Isett, J. L. Munoz-Rodriguez, A. F. List, M. L. Narro, S. J. Miller, N. C. Merchant and B. W. Futscher (2004): “Epigenomic changes during leukemia cell differentiation: Analysis of histone acetylation and cytosine methylation using CpG island microarrays,” J. Pharmacol. Exp. Ther., 311, 968–981.Suche in Google Scholar

Parkitna, J. R., A. Bilbao, C. Rieker, D. Engblom, M. Piechota, A. Nordheim, R. Spanagel and G. Schtz (2010): “Loss of the serum response factor in the dopamine system leads to hyperactivity,” The FASEB J., 24, 2427–2435.Suche in Google Scholar

Pyeon, D., M. A. Newton, P. F. Lambert, J. A. den Boon, S. Sengupta, C. J. Marsit, C. D. Woodworth, J. P. Connor, T. H. Haugen, E. M. Smith, K. T. Kelsey, L. P. Turek and P. Ahlquist (2007): “Fundamental differences in cell cycle deregulation in human papillomavirus positive and human papillomavirus negative head/neck and cervical cancers,” Cancer Res., 67, 4605–4619.10.1158/0008-5472.CAN-06-3619Suche in Google Scholar PubMed PubMed Central

Rashi-Elkeles, S., R. Elkon, N. Weizman, C. Linhart, N. Amariglio, G. Sternberg, G. Rechavi, A. Barzilai, R. Shamir and Y. Shiloh (2005): “Parallel induction of ATM-dependent pro- and antiapoptotic signals in response to ionizing radiation in murine lymphoid tissue,” Oncogene, 25, 0950–9232.10.1038/sj.onc.1209189Suche in Google Scholar PubMed

Ray, P., L. Zheng, J. Lucas and L. Carin (2014): “Bayesian joint analysis of heterogeneous genomics data,” Bioinformatics, 30, 1370–1376.10.1093/bioinformatics/btu064Suche in Google Scholar PubMed

Sandy, A., M. Jones and I. Maillard (2012): Notch signaling and development of the hematopoietic system. In: Reichrath, J., Reichrath, S. (Eds.), Notch Signaling in Embryology and Cancer, Advances in Experimental Medicine and Biology, volume 727, Springer: USA, pp. 71–88.10.1007/978-1-4614-0899-4_6Suche in Google Scholar PubMed

Schmidt, M. N., O. Winther and L. K. Hansen (2009): “Bayesian non-negative matrix factorization,” In: Independent Component Analysis and Signal Separation, International Conference on, Lecture Notes in Computer Science (LNCS), volume 5441, Springer, Lecture Notes in Computer Science (LNCS), volume 5441, pp. 540–547.Suche in Google Scholar

Schuringa, J. J., K. Y. Chung, G. Morrone and M. A. Moore (2004): “Constitutive activation of STAT5A promotes human hematopoietic stem cell self-renewal and erythroid differentiation,” J. Exp. Med., 200, 623–635.Suche in Google Scholar

Sesto, A., M. Navarro, F. Burslem and J. L. Jorcano (2002): “Analysis of the ultraviolet B response in primary human keratinocytes using oligonucleotide microarrays,” Proc. Nat. Acad. Sci., 99, 2965–2970.Suche in Google Scholar

Shamir, R. (2010): “Analysis of DNA chips and gene networks,” Tel Aviv University Blavatnik School of Computer Science. Lecture 14a.Suche in Google Scholar

Shen, H. (2007): Bayesian analysis in cancer pathway studies and probabilistic pathway annotation, Ph.D. thesis, Duke University, URL http://www.stat.duke.edu/people/theses/ShenH.pdf.Suche in Google Scholar

Smirnov, D. A., L. Brady, K. Halasa, M. Morley, S. Solomon and V. G. Cheung (2012): “Genetic variation in radiation-induced cell death,” Genome Res., 22, 332–339.Suche in Google Scholar

Subramanian, A., P. Tamayo, V. K. Mootha, S. Mukherjee, B. L. Ebert, M. A. Gillette, A. Paulovich, S. L. Pomeroy, T. R. Golub, E. S. Lander and J. P. Mesirov (2005): “Gene set enrichment analysis: A knowledge-based approach for interpreting genome-wide expression profiles,” Proc. Nat. Acad. Sci. USA, 102, 15545–15550.10.1073/pnas.0506580102Suche in Google Scholar PubMed PubMed Central

Tamayo, P., G. Steinhardt, A. Liberzon and J. P. Mesirov (2012): “The limitations of simple gene set enrichment analysis assuming gene independence,” Stat. Method. Med. Res.10.1177/0962280212460441Suche in Google Scholar PubMed PubMed Central

Taylor, K. H., K. E. Pena-Hernandez, J. W. Davis, G. L. Arthur, D. J. Duff, H. Shi, F. B. Rahmatpanah, O. Sjahputera and C. W. Caldwell (2007): “Large-scale CpG methylation analysis identifies novel candidate genes and reveals methylation hotspots in acute lymphoblastic leukemia,” Cancer Res., 67, 2617–2625.Suche in Google Scholar

Trowbridge, J. J., M. P. Scott and M. Bhatia (2006): “Hedgehog modulates cell cycle regulators in stem cells to control hematopoietic regeneration,” Proc. Nat. Acad. Sci., 103, 14134–14139.Suche in Google Scholar

Vastrik, I., P. D’Eustachio, E. Schmidt, G. Joshi-Tope, G. Gopinath, D. Croft, B. de Bono, M. Gillespie, B. Jassal, S. Lewis, L. Matthews, G. Wu, E. Birney and L. Stein (2007): “Reactome: a knowledge base of biologic pathways and processes,” Genome Biol., 8, R39.Suche in Google Scholar

Wang, Y., A. V. Krivtsov, A. U. Sinha, T. E. North, W. Goessling, Z. Feng, L. I. Zon and S. A. Armstrong (2010): “The Wnt/β-catenin pathway is required for the development of leukemia stem cells in AML,” Science, 327, 1650–1653.10.1126/science.1186624Suche in Google Scholar PubMed PubMed Central

Wilusz, M. and M. Majka (2008): “Role of the Wnt/β-catenin network in regulating hematopoiesis,” Arch. Immunol. Ther. Ex., 56, 257–266.Suche in Google Scholar

Zheng, L. and J. Lucas (2012): “Uncover cancer genomics by jointly analysing aneuploidy and gene expression,” In: Aneuploidy in Health and Disease, InTech, 22–41, URL http://www.intechopen.com/books/aneuploidy-in-health-and-disease/joint-analysis-of-aneuploidy-and-gene-expression.10.5772/36338Suche in Google Scholar

Zhou, Y. -H., W. T. Barry and F. A. Wright (2013): “Empirical pathway analysis, without permutation,” Biostatistics, 14, 573–585.10.1093/biostatistics/kxt004Suche in Google Scholar PubMed PubMed Central


Supplemental Material

The online version of this article (DOI 10.1515/sagmb-2013-0043) offers supplementary material, available to authorized users.



Article note

Availability: The source code for this model is written in MATLAB, and has been made publicly available in http://linglingzheng.com/code/

Data: The radiation data has been published, and can be found in GEO with Series record GSE52403 in http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE52403.


Published Online: 2014-6-17
Published in Print: 2014-8-1

© 2014 by De Gruyter

Heruntergeladen am 17.11.2025 von https://www.degruyterbrill.com/document/doi/10.1515/sagmb-2013-0043/pdf?lang=de
Button zum nach oben scrollen