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Posts tagged “biochemical network

Metabolomics and Beyond: Challenges and Strategies for Next-gen Omic Analyses

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Recently I had the pleasure of giving lecture for the Metabolomics Society on Challenges and Strategies for Next-gen Omic Analyses. You can check out all of my slides and video of the lecture below.


Mapping to the MetabolOMIC Manifold


I recently had the pleasure of giving a presentation on one of my favorite topics, network mapping, and its application to metabolomic and genomic data integration. You can check out the full presentation below.


2014 Metabolomic Data Analysis and Visualization Workshop and Tutorials

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Recently I had the pleasure of teaching statistical and multivariate data analysis and visualization at the annual Summer Sessions in Metabolomics 2014, organized by the NIH West Coast Metabolomics Center.


Similar to last year, I’ve posted all the content (lectures, labs and software) for any one to follow along with at their own pace. I also plan to release videos for all the lectures and labs including use cases for the freely available data analysis software listed below.


You can check out the introduction lecture to the covered material below.



New additions to the course include lecture and lab on Data normalization and updated and improved software.


Software


Stay tuned for videos of all of the material!

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2014 Metabolomics Data Analysis and Visualization Tutorials Dmitry Grapov is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.


Diabetes associated metabolomic perturbations in NOD mice


Recently I was lucky enough to publish some of my research findings in the Journal Metabolomics. You can check out the full paper, 10.1007/s11306-014-0706-2,  or take a look at the abstract and figures below.
 
 
ABSTRACT
Non-obese diabetic (NOD) mice are a widely-used model of type 1 diabetes (T1D). However, not all animals develop overt diabetes. This study examined the circulating metabolomic profiles of NOD mice progressing or not progressing to T1D. Total beta-cell mass was quantified in the intact pancreas using transgenic NOD mice expressing green fluorescent protein under the control of mouse insulin I promoter. While both progressor and non-progressor animals displayed lymphocyte infiltration and endoplasmic reticulum stress in the pancreas tissue, overt T1D did not develop until animals lost ~70 % of the total beta-cell mass. Gas chromatography time of flight mass spectrometry was used to measure >470 circulating metabolites in male and female progressor and non-progressor animals (n = 76) across a wide range of ages (neonates to >40-week). Statistical and multivariate analyses were used to identify age and sex independent metabolic markers which best differentiated progressor and non-progressor animals’ metabolic profiles. Key T1D-associated perturbations were related with: (1) increased plasma glucose and reduced 1,5-anhydroglucitol markers of glycemic control; (2) increased allantoin, gluconic acid and nitric acid-derived saccharic acid markers of oxidative stress; (3) reduced lysine, an insulin secretagogue; (4) increased branched-chain amino acids, isoleucine and valine; (5) reduced unsaturated fatty acids including arachidonic acid; and (6) perturbations in urea cycle intermediates suggesting increased arginine-dependent NO synthesis. Together these findings highlight the strength of the unique approach of comparing progressor and non-progressor NOD mice to identify metabolic perturbations involved in T1D progression.

 
 
Figure1


Fig. 1 Immune cell infiltration and beta-cell destruction in prediabetic NOD mice. A Visualization of spatial islet distribution in the context of the vascular network in the intact pancreas. A prediabetic NOD mouse at 27-week. B The body region of the NOD mouse shown in A. Note that substantial beta-cell destruction is observed in the NOD pancreas (i.e. a loss of GFP-expressing beta-cells). C Intraislet capillary network in the body region of a wild-type mouse at 21-week. D Immunohistochemical staining. Insulin (green), glucagon (red), somatostatin (white) and nuclei (blue). E Hypertrophic islet with massive infiltration of T-lymphocytes. (a) Hematoxylin-Eosin (HE) staining of the islet showing peripheral- and intra-islet infiltrating lymphocytes and remaining endocrine islet cells. (b) A serial section stained for CD4-positive lymphocytes by ABC-staining (brown). c A serial section stained for CD8-positive lymphocytes. F Ultrastructural analysis of hypertrophic islets in non-diabetic and diabetic littermates. (a) Non-diabetic male NOD mouse (41-week old, 4-h fasting BG: 136 mg/dL) showing a hyperactive beta-cell with lymphocyte infiltration and vesicles without dense core granules. (b) Beta-cells in diabetic female NOD mouse (40-week old, 4-h fasting BG: 559 mg/dL) appears to be intact despite the presence of ongoing insulitis. G Progressive degradation of endoplasmic reticulum (ER). (a) Well-developed ER (ER) in a beta-cell undergoing insulitis. (b) ER degradation. Ribosomes are detached (shed) from the ER membrane and are aggregated (ER). Nuclear damage is seen with the formation of foam-like structures (N). Immature granules with less dense cores (G) as well as cytoplasmic liquefaction (CL) are observed. (c) ER membrane breakdown. ER membrane breakdown resulted in aggregation of shed ribosomes (ER). An adjacent PP-cell (PP) appears to be intact (identified by characteristic moderately dense cores of pancreatic polypeptide-containing secretory granules). (d) Beta-cell degradation. ER swelling (ER), ribosome shedding, amorphous cytoplasmic material (R) and cytoplasmic, liquefaction (L) are observed in the same beta-cell
 

Figure2

Fig. 2 Progression of autoimmune diabetes in NOD mice. A (a) Virtual slice capture of a whole mouse pancreas from mouse insulin promoter I (MIP)-GFP mice on NOD background. (b) Measured beta-cell/islet distribution. (c) Corresponding 3D scatter plot of islet parameters depicts distribution of islets with various sizes and shapes. Each dot represents a single islet. B (a) Representative data showing islet growth in wild-type mice at 20- and 28-week of age. (b) Examples of beta-cell loss at 20-week (non-diabetic) and 28-week (diabetic) in NOD mice. C Heterogeneous beta-cell loss in NOD mice. Frequency is plotted against islet size. D Three distinct groups in the development of T1D in NOD mice. 3D scatter plot showing the relationship among blood glucose levels (BG), total beta-cell area and age. Three groups of mice are color-coded as diabetic mice (red), young mice with normoglycemia (<25 week; green) and old mice with normoglycemia (25–40 week; blue)

Figure3

Fig. 3 Biochemical network displaying metabolic differences between diabetic and non-diabetic NOD mice. Metabolites are connected based on biochemical relationships (blue, KEGG RPAIRS) or structural similarity (violet, Tanimoto coefficient ≥0.7). Metabolite size and color represent the importance (O-PLS-DA model loadings, LV 1) and relative change (gray p adj > 0.05; green increase; red decrease) in diabetic compared non-diabetic NOD mice. Shapes display metabolites’ molecular classes or biochemical sub-domains and top descriptors of T1D-associated metabolic perturbations (Table 1) are highlighted with thick black borders

Figure4

Fig. 4 Partial correlation network displaying associations between all type 1 diabetes-dependent metabolomic perturbations. All significantly altered metabolites (p adj ≤ 0.05, Supplemental Table S3) are connected based on partial correlations (p adj ≤ 0.05). Edge width displays the absolute magnitude and color the direction (orange positive; blue negative) of the partial-coefficient of correlation. Metabolite size and color represent the importance (O-PLS-DA model loadings, LV 1) and relative change (gray p adj > 0.05; green increase; red decrease) in diabetic compared non-diabetic NOD mice. Shapes display metabolites’ molecular classes or biochemical sub-domains (see Fig. 3 legend), and top descriptors of T1D-associated metabolic perturbations (Table 1) are highlighted with thick black borders


In conclusion, we identified marked differences in the rates of progression of NOD mice to T1D. Metabolomic analysis was used to identify age and sex independent metabolic markers, which may explain this heterogeneity. Future studies combining metabolic end points (as they correlate with beta-cell mass) and genetic risk profiles will ultimately lead to a more complete understanding of disease onset and progression.


Multivariate Data Analysis and Visualization Through Network Mapping


Recently I had the pleasure of speaking about one of my favorite topics, Network Mapping. This is a continuation of a general theme I’ve previously discussed and involves the merger of statistical and multivariate data analysis results with a network.



Over the past year I’ve been working on two major tools, DeviumWeb and MetaMapR, which aid the process of biological data (metabolomic) network mapping.

deviuWeb

DeviumWeb– is a shiny based GUI written in R which is useful for:

  • data manipulation, transformation and visualization
  • statistical analysis (hypothesis testing, FDR, power analysis, correlations, etc)
  • clustering (heiarchical, TODO: k-means, SOM, distribution)
  • principal components analysis (PCA)
  • orthogonal partial least squares multivariate modeling (O-/PLS/-DA)

 
MetaMapR

MetaMapR– is also a shiny based GUI written in R which is useful for calculation and visualization of various networks including:

  • biochemical
  • structural similarity
  • mass spectral similarity
  • correlation


Both of theses projects are under development, and my ultimate goal is to design a one-stop-shop ecosystem for network mapping.


In addition to network mapping,the video above and presentation below also discuss normalization schemes for longitudinal data and genomic, proteomic and metabolomic functional analysis both on a pathway and global level.


As always happy network mapping!

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ASMS 2014


I’ve recently participated in the American Society of Mass Spectrommetry (ASMS) conference and had a great time. I met some great people and have a few new ideas for future projects. Specifically giving a go at using self-organizing maps (SOM) and  the R package mcclust  for clustering alternatives to hierarchical and k-means methods.


I had the pleasure of speaking at the conference in the Informatics-Metabolomics section, and was also a co-author on a project detailing a multi-metabolomics strategy (primary metabolites, lipids, and oxylipins) for the study of type 1 diabetes in an animal model. Keep an eye out for my full talk in an upcoming post.

ASMS 2014 j fahrman


Enrichment Network


Enrichment is beyond random occurrence within a category. Networks can represent relationships among variables. Enrichment networks display relationships among variables which are over represented compared to random chance.


Next is  a tutorial for making enrichment networks for biological (metabolomic) data in R using the KEGG database.


High Dimensional Biological Data Analysis and Visualization


High dimensional biological data shares many qualities with other forms of data. Typically it is wide (samples << variables), complicated by experiential design and made up of complex relationships driven by both biological and analytical sources of variance. Luckily the powerful combination of R, Cytoscape (< v3) and the R package RCytoscape can be used to generate high dimensional and highly informative representations of complex biological (and really any type of) data. Check out the following examples of network mapping in action or view a more indepth presentation of the techniques used below.


Partial correlation network highlighting changes in tumor compared to control tissue from the same patient.

Tissue network cancer


Biochemical and structural similarity network of changes in tumor compared to control tissue from the same patient.

Cancer tissue network


Hierarchical clusters (color) mapped to a biochemical and structural similarity network displaying difference before and after drug administration.

cough syrup network


Partial correlation network displaying changes in metabolite relationships in response to drug treatment.

Treatment response network


Partial correlation network displaying changes in disease and response to drug treatment.

Treatment effects network


Check out the full presentation below.

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Tutorials- Statistical and Multivariate Analysis for Metabolomics


2014 winter LC-MS stats courseI recently had the pleasure in participating in the 2014 WCMC Statistics for Metabolomics Short Course. The course was hosted by the NIH West Coast Metabolomics Center and focused on statistical and multivariate strategies for metabolomic data analysis. A variety of topics were covered using 8 hands on tutorials which focused on:

  • data quality overview
  • statistical and power analysis
  • clustering
  • principal components analysis (PCA)
  • partial least squares (O-/PLS/-DA)
  • metabolite enrichment analysis
  • biochemical and structural similarity network construction
  • network mapping


I am happy to have taught the course using all open source software, including: R, and Cytoscape. The data analysis and visualization were done using Shiny-based apps:  DeviumWeb and MetaMapR. Check out some of the slides below or download all the class material and try it out for yourself.

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2014 WCMC LC-MS Data Processing and Statistics for Metabolomics by Dmitry Grapov is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

Special thanks to the developers of Shiny and Radiant by Vincent Nijs.


Introduction to Network Mapping

name networkNetwork mapping is a high-dimensional data visualization technique which can be applied to virtually any type of data. I recently gave a tutorial on the basics of network mapping where each participants generated a mapped network for their name.

Download the full tutorial at TeachingDemos, and then follow along with the tutorial at your own pace.

 

Happy  network mapping!


Featured Network in Chemical and Engineering News (C&EN)


I am happy to announce the release of MetaMapR (v1.2.0).


New features include: 

  • An independent module for biological database identifier translations using the Chemical Translation System (CTS)
  • a retention time filter for mass spectral connections
  • increase in calculation speed


An application of MetaMapR was recently featured in an article in the Nov. 4th 2013 issue of Chemical & Engineering News (C&EN) , 91(44). This tool was used to generate a network of > 1200 metabolites based on enzymatic transformations and structural similarities.


C and E figure

The full article can be found be found here as well as the original image.


Connecting Data with Context: Metabolomic Examples

I recently gave a presentation of some of my work in network mapping to my research lab. The following covers my progress in the development of my metabolomic network mapping tool MetaMapR, and its application to a variety of data sets including a comparison of normal and malignant lung tissue from the same patient.


Sessions in Metabolomics 2013

The international summer sessions in metabolomics 2013 came to a happy conclusion this past Friday Sept 6th 2013.  I had the pleasure of teaching the topics covering metabolomic data analysis. The class was split into lecture and lab sections. The lab section consisted of a hands on data analysis of:

  • fresh vs. lyophilized treatment comparison for tomatillo  leaf primary metabolomics
  • tomatillo vs. pumpkin leaf primary metabolites

The majority of the data analyses were implemented using the open source software imDEV and Devium-web.

Download the FULL LAB. Take a look at the goals folder for each lesson.  You can follow along with the lesson plans by looking at each subsections respective excel file (.xlsx). When you are done with a section unhide all the worksheets (right click on a tab at the bottom) to view the solutions .

The lectures, preceding the lab, covered the basics of metabolomic data analysis  including:

  • Data Quality Overview and Statistical Analysis
  • Multivariete Data analysis
  • Metabolomic Case Studies

Biochemical, Chemical and Mass Spectral Similarity Network

Here is an example of a network leveraging three dominant aspects of metabolomic experiments (biochemical, chemical and mass spectral knowledge) to connect measured variables. This is a network for a blinded data set (sample ids are not known), which I’ve made for a member of my lab presenting their work at the Metabolomics Society Conference in Glasgow, Scotland.

network

With out knowing the experimental design we can still analyze our data for analytical effects. For example below is a principal components analysis of ~400 samples and 600 variables, where I’ve annotated the sample scores to show data aquisition date (color) and experimental samples or laboratory quality controls (shape).  One thing to look for are trends or scores grouping in the PCA scores which are correlated to analytical conditions like, batch, date, technician, etc.

PCA scores

Finally we can take a look at the PCA variable loadings which highlights a major bottleneck in metabolomics experiments, the large amount of structurally unknown molecular features.

PCA loadings

Even using feature rich electron impact mass spectra (GC/TOF) only 40% of the unknown variables could be connected to known species based on a cosine correlation >0.75.  To give you an idea the cosine correlation or dot product between the mass spectra of two structurally very similar molecules xylose and xylitol is ~ 0.8.

pic


Network Mapping Video

Here are a video and slides for a presentation of mine about my favorite topic :


American Society for Mass Spectrometry 2013

I am getting ready to present at the upcoming American Society for Mass Spectrometry (ASMS) conference in Minneapolis, Minnesota (dont’cha know).

If you are around check out my talk  in the section Oral: ThOB am – Informatics: Metabolomics on Thursday (06/14) at 8:30 am in room L100. Here is teaser

WCMC network

Above is a network representation of biochemical (red edges, KEGG RPAIRS) and structural similarities (gray edges, Tanimoto coefficient> 0.7) of > 1100 biological molecules (see here for some of their descriptions). Keep an eye out for all the R code used to generate this network as well as all the slides from my talk.

Here is my talk abstract.

Multivariate and network tools for analysis and visualization of metabolomic data
Dmitry Grapov1, 2; Oliver Fiehn1, 2
1West Coast Metabolomics Center, Davis, CA; 2University of California Davis, Davis, California
NOVEL ASPECT: A software tool for calculation and mapping of statistical and multivariate results from metabolomic experiments into biologically relevant contexts.
————————
INTRODUCTION: While a variety of tools capable of producing network representations of metabolomic data exist, none are fully integrated with statistical and multivariate methods necessary to analyze, visualize and summarize the high dimensional data. We have developed an open source toolset for the analysis of high dimensional biological data which combines the computational capabilities of the R statistical programming environment with the network mapping and visualization features of Cytoscape. A graphical user interface is used to seamlessly integrate calculation and interpretation of statistical and multivariate results in the context of network graphs which are constructed based on biological relationships, chemical similarities or empirical variable dependencies.
—————
METHODS: An R based GUI utilizing RCytoscape and CytoscapeRPC is used to connect R and Cytoscape. Data import, manipulation  and export are achieved through an interface to MS Excel and Google Docs. R packages provide a variety of analyses methods including: parametric and non-parametric multiple hypotheses testing, false discovery rate correction, exploratory principal and independent components analyses, hierarchical and model based clustering, and multivariate predictive modeling such as partial least squares and support vector machines. Relationships between biological parameters can be represented in the form of networks which are connected based on user defined edge lists or from pubchem chemical identifiers which are used to construct biochemical and chemical similarity networks based on the KEGG reactant pairs and Tanimoto distances, or Gaussian Markov networks based partial correlations.
—————-
ABSTRACT: Comparisons of plasma primary metabolite excursion patterns during an oral glucose tolerance test (OGTT) were used to model changes in metabolism associated with a diet and exercise intervention. Plasma aliquots, taken at 30 minute intervals (0-120 minutes) were analyzed by GC/TOF and used to compare metabolite levels (n=323) in a cohort of overweight women before and after a 14 week dietary and exercise regimen. Mixed effects models, partial least squares and partial least squares discriminant analysis (PLS-DA)  were used to study OGTT and intervention-associated changes in metabolite baselines, area under the curve for OGTT-associated excursions , and metabolite time course patterns. Metabolic changes due to the oral infusion of glucose were visualized by mapping statistical test p-values and intervention-adjusted PLS model for time during the OGTT variable coefficient weights into a network connected based on KEGG reactant pairs and Tanimoto distances > 70. Vertices, representing metabolites were sized and colored based on the absolute PLS coefficient magnitude and sign respectively. Metabolites showing significant perturbations during the OGTT (false discovery rate (q = 0.05) adjusted p-value < 0.05) were highlighted with node-inset graphs displaying  means and confidence intervals during the time course for before and after intervention comparisons. This network was useful for identifying OGTT-associated interactions between the major biochemical domains (lipids, amino acids, organic acids, and carbohydrates). In a follow-up analysis a Gaussian Markov partial correlation network was used to investigate intervention-associated changes in metabolite-metabolite and metabolite-clinical parameter (insulin, hormones) dependency relationships.

Tutorial- Building Biological Networks

I love networks! Nothing is better for visualizing complex multivariate relationships be it social, virtual or biological.Bionetwork1

I recently gave a hands-on network building tutorial using R and Cytoscape to build large biological networks. In these networks Nodes represent metabolites and edges can be many things, but I specifically focused on biochemical relationships and chemical similarities. Your imagination is the limit.

genotype network

 

network DM

If you are interested check out the presentation below.

Here is all the R code and links to relevant data you will need to let you follow along with the tutorial.

</pre>
#load needed functions: R package in progress - "devium", which is stored on github
source("http://pastebin.com/raw.php?i=Y0YYEBia")
<pre>
# get sample chemical identifiers here:https://docs.google.com/spreadsheet/ccc?key=0Ap1AEMfo-fh9dFZSSm5WSHlqMC1QdkNMWFZCeWdVbEE#gid=1
#Pubchem CIDs = cids
cids # overview
nrow(cids) # how many
str(cids) # structure, wan't numeric 
cids<-as.numeric(as.character(unlist(cids))) # hack to break factor

#get KEGG RPAIRS
#making an edge list based on CIDs from KEGG reactant pairs
KEGG.edge.list<-CID.to.KEGG.pairs(cid=cids,database=get.KEGG.pairs(),lookup=get.CID.KEGG.pairs())
head(KEGG.edge.list)
dim(KEGG.edge.list) # a two column list with CID to CID connections based on KEGG RPAIS
# how did I get this?
#1) convert from CID to KEGG using get.CID.KEGG.pairs(), which is a table stored:https://gist.github.com/dgrapov/4964546
#2) get KEGG RPAIRS using get.KEGG.pairs() which is a table stored:https://gist.github.com/dgrapov/4964564
#3) return CID pairs

#get EDGES based on chemical similarity (Tanimoto distances >0.07)
tanimoto.edges<-CID.to.tanimoto(cids=cids, cut.off = .7, parallel=FALSE)
head(tanimoto.edges)
# how did I get this?
#1) Use R package ChemmineR to querry Pubchem PUG to get molecular fingerprints
#2) calculate simialrity coefficient
#3) return edges with similarity above cut.off

#after a little bit of formatting make combined KEGG + tanimoto edge list
# https://docs.google.com/spreadsheet/ccc?key=0Ap1AEMfo-fh9dFZSSm5WSHlqMC1QdkNMWFZCeWdVbEE#gid=2

#now upload this and a sample node attribute table (https://docs.google.com/spreadsheet/ccc?key=0Ap1AEMfo-fh9dFZSSm5WSHlqMC1QdkNMWFZCeWdVbEE#gid=1)
#to Cytoscape 


You can also download all the necessary materials HERE, which include:

  1. tutorial in powerpoint
  2. R script
  3. Network edge list and node attributes table
  4. Cytoscape file
Happy network making!

 


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