Molecular Biology Commons^™

Some Statistical Issues In Microarray Gene Expression Data, Matthew S. Mayo, Byron J. Gajewski, Jeffrey S. Morris

Jeffrey S. Morris

In this paper we discuss some of the statistical issues that should be considered when conducting experiments involving microarray gene expression data. We discuss statistical issues related to preprocessing the data as well as the analysis of the data. Analysis of the data is discussed in three contexts: class comparison, class prediction and class discovery. We also review the methods used in two studies that are using microarray gene expression to assess the effect of exposure to radiofrequency (RF) fields on gene expression. Our intent is to provide a guide for radiation researchers when conducting studies involving microarray gene expression …

Probability Of Real -Time Detection Vs Probability Of Infection For Aerosolized Biowarfare Agents: A Model Study., Alexander G. Sabelnikov, Vladimir Zhukov, C Ruth Kempf

Alexander G Sabelnikov

No abstract provided.

Shrinkage Estimation For Sage Data Using A Mixture Dirichlet Prior, Jeffrey S. Morris, Keith A. Baggerly, Kevin R. Coombes

Jeffrey S. Morris

Serial Analysis of Gene Expression (SAGE) is a technique for estimating the gene expression profile of a biological sample. Any efficient inference in SAGE must be based upon efficient estimates of these gene expression profiles, which consist of the estimated relative abundances for each mRNA species present in the sample. The data from SAGE experiments are counts for each observed mRNA species, and can be modeled using a multinomial distribution with two characteristics: skewness in the distribution of relative abundances and small sample size relative to the dimension. As a result of these characteristics, a given SAGE sample will fail …

An Introduction To High-Throughput Bioinformatics Data, Keith A. Baggerly, Kevin R. Coombes, Jeffrey S. Morris

Jeffrey S. Morris

High throughput biological assays supply thousands of measurements per sample, and the sheer amount of related data increases the need for better models to enhance inference. Such models, however, are more effective if they take into account the idiosyncracies associated with the specific methods of measurement: where the numbers come from. We illustrate this point by describing three different measurement platforms: microarrays, serial analysis of gene expression (SAGE), and proteomic mass spectrometry.

Bayesian Mixture Models For Gene Expression And Protein Profiles, Michele Guindani, Kim-Anh Do, Peter Mueller, Jeffrey S. Morris

Jeffrey S. Morris

We review the use of semi-parametric mixture models for Bayesian inference in high throughput genomic data. We discuss three specific approaches for microarray data, for protein mass spectrometry experiments, and for SAGE data. For the microarray data and the protein mass spectrometry we assume group comparison experiments, i.e., experiments that seek to identify genes and proteins that are differentially expressed across two biologic conditions of interest. For the SAGE data example we consider inference for a single biologic sample.

Analysis Of Mass Spectrometry Data Using Bayesian Wavelet-Based Functional Mixed Models, Jeffrey S. Morris, Philip J. Brown, Keith A. Baggerly, Kevin R. Coombes

Jeffrey S. Morris

In this chapter, we demonstrate how to analyze MALDI-TOF/SELDITOF mass spectrometry data using the wavelet-based functional mixed model introduced by Morris and Carroll (2006), which generalizes the linear mixed models to the case of functional data. This approach models each spectrum as a function, and is very general, accommodating a broad class of experimental designs and allowing one to model nonparametric functional effects for various factors, which can be conditions of interest (e.g. cancer/normal) or experimental factors (blocking factors). Inference on these functional effects allows us to identify protein peaks related to various outcomes of interest, including dichotomous outcomes, categorical …

Ethylene Stimulates Nutations That Are Dependent On The Etr1 Receptor, Brad M. Binder, Ronan C. O'Malley, Wuyi Wang, Tobias C. Zutz, Anthony B. Bleeker

Brad M. Binder

Ethylene influences a number of processes in Arabidopsis (Arabidopsis thaliana) through the action of five receptors. In this study, we used high-resolution, time-lapse imaging to examine the long-term effects of ethylene on growing, etiolated Arabidopsis seedlings. These measurements revealed that ethylene stimulates nutations of the hypocotyls with an average delay in onset of over 6 h. The nutation response was constitutive in ctr1-2 mutants maintained in air, whereas ein2-1 mutants failed to nutate when treated with ethylene. Ethylene-stimulated nutations were also eliminated in etr1-7 loss-of-function mutants. Transformation of the etr1-7 mutant with a wild-type genomic ETR1 transgene rescued the nutation …

Soluble Fibrin Inhibits Monocyte Adherence And Cytotoxicity Against Tumor Cells: Implications For Cancer Metastasis, John Biggerstaff, Brandy Weidow, Jacqueline Vidosh, Judith Dexheimer, Shonak Patel, Pretesh Patel

John Biggerstaff

Background Soluble fibrin (sFn) is a marker for disseminated intravascular coagulation and may have prognostic significance, especially in metastasis. However, a role for sFn in the etiology of metastatic cancer growth has not been extensively studied. We have reported that sFn cross-linked platelet binding to tumor cells via the major platelet fibrin receptor αIIbβ3, and tumor cell CD54 (ICAM-1), which is the receptor for two of the leukocyte β2 integrins (αLβ2 and aMβ2). We hypothesized that sFn may also affect leukocyte adherence, recognition, and killing of tumor cells. Furthermore, in a rat experimental metastasis model sFn pre-treatment of tumor cells …

Improved Peak Detection And Quantification Of Mass Spectrometry Data Acquired From Surface-Enhanced Laser Desorption And Ionization By Denoising Spectra With The Undecimated Discrete Wavelet Transform, Kevin R. Coombes, Spiros Tsavachidis, Jeffrey S. Morris, Keith A. Baggerly, Henry M. Kuerer

Jeffrey S. Morris

Background: Mass spectrometry, especially surface enhanced laser desorption and ionization (SELDI) is increasingly being used to find disease-related proteomic patterns in complex mixtures of proteins derived from tissue samples or from easily obtained biological fluids such as serum, urine, or nipple aspirate fluid. Questions have been raised about the reproducibility and reliability of peak quantifications using this technology. For example, Yasui and colleagues opted to replace continuous measures of the size of a peak by a simple binary indicator of its presence or absence in their analysis of a set of spectra from prostate cancer patients.

Methods: We collected nipple …

Pooling Information Across Different Studies And Oligonucleotide Microarray Chip Types To Identify Prognostic Genes For Lung Cancer., Jeffrey S. Morris, Guosheng Yin, Keith A. Baggerly, Chunlei Wu, Li Zhang

Jeffrey S. Morris

Our goal in this work is to pool information across microarray studies conducted at different institutions using two different versions of Affymetrix chips to identify genes whose expression levels offer information on lung cancer patients’ survival above and beyond the information provided by readily available clinical covariates. We combine information across chip types by identifying “matching probes” present on both chips, and then assembling them into new probesets based on Unigene clusters. This method yields comparable expression level quantifications across chips without sacrificing much precision or significantly altering the relative ordering of the samples. We fit a series of multivariable …

Expression Of G-Protein Inwardly Rectifying Potassium Channels (Girks) In Lung Cancer Cell Lines, Howard Plummer 3rd, Madhu Dhar, Maria Cekanova Ms, Rndr, Phd, Hildegard Schuller

Maria Cekanova MS, RNDr, PhD

BACKGROUND: Previous data from our laboratory has indicated that there is a functional link between the beta-adrenergic receptor signaling pathway and the G-protein inwardly rectifying potassium channel (GIRK1) in human breast cancer cell lines. We wanted to determine if GIRK channels were expressed in lung cancers and if a similar link exists in lung cancer. METHODS: GIRK1-4 expression and levels were determined by reverse transcription polymerase chain reaction (RT-PCR) and real-time PCR. GIRK protein levels were determined by western blots and cell proliferation was determined by a 5-bromo-2'-deoxyuridine (BrdU) assay. RESULTS: GIRK1 mRNA was expressed in three of six small …

Serum Proteomics Profiling: A Young Technology Begins To Mature, Kevin R. Coombes, Jeffrey S. Morris, Jianhua Hu, Sarah R. Edmondson, Keith A. Baggerly

Jeffrey S. Morris

No abstract provided.

Signal In Noise: Evaluating Reported Reproducibility Of Serum Proteomic Tests For Ovarian Cancer, Keith A. Baggerly, Jeffrey S. Morris, Sarah R. Edmonson, Kevin R. Coombes

Jeffrey S. Morris

Proteomic profi ling of serum initially appeared to be dramatically effective for diagnosis of early-stage ovarian cancer, but these results have proven diffi cult to reproduce. A recent publication reported good classifi cation in one dataset using results from training on a much earlier dataset, but the authors have since reported that they did not perform the analysis as described. We examined the reproducibility of the proteomic patterns across datasets in more detail. Our analysis reveals that the pattern that enabled successful classifi cation is biologically implausible and that the method, properly applied, does not classify the data accurately. We …

Molecular Characterization Of A Isoenzyme Of The Targeting Peptide Degrading Protease, Prep2- Catalysis, Subcellular Localization, Expression And Evolution, S. Bhushan, A. Stahl, S. Nilsson, B. Lefebvre, D. Mcwilliams, S.J. Wright, M. Seki, D.A. Liberles, K. Shinozaki, Barry D. Bruce, M. Boutry, E. Glaser

Barry D. Bruce

We have previously identified a zinc metalloprotease involved in the degradation of mitochondrial and chloroplast targeting peptides, the presequence protease (PreP). In the Arabidopsis thaliana genomic database, there are two genes that correspond to the protease, the zinc metalloprotease (AAL90904) and the putative zinc metalloprotease (AAG13049). We have named the corresponding proteins AtPreP1 and AtPreP2, respectively. AtPreP1 and AtPreP2 show significant differences in their targeting peptides and the proteins are predicted to be localized in different compartments. AtPreP1 was shown to degrade both mitochondrial and chloroplast targeting peptides and to be dual targeted to both organelles using an ambiguous targeting …

High-Resolution Serum Proteomic Patterns For Ovarian Cancer Detection, Keith A. Baggerly, Sarah R. Edmonson, Jeffrey S. Morris, Kevin R. Coombes

Jeffrey S. Morris

No abstract provided.

A Hidden Markov Model Capable Of Predicting And Discriminating Β-Barrel Outer Membrane Proteins, Pantelis G. Bagos, Theodore D. Liakopoulos, Ioannis C. Spyropoulos, Stavros J. Hamodrakas

Pantelis Bagos

BACKGROUND: Integral membrane proteins constitute about 20-30% of all proteins in the fully sequenced genomes. They come in two structural classes, the alpha-helical and the beta-barrel membrane proteins, demonstrating different physicochemical characteristics, structure and localization. While transmembrane segment prediction for the alpha-helical integral membrane proteins appears to be an easy task nowadays, the same is much more difficult for the beta-barrel membrane proteins. We developed a method, based on a Hidden Markov Model, capable of predicting the transmembrane beta-strands of the outer membrane proteins of gram-negative bacteria, and discriminating those from water-soluble proteins in large datasets. The model is trained …

Quality Control And Peak Finding For Proteomics Data Collected From Nipple Aspirate Fluid Using Surface Enhanced Laser Desorption And Ionization., Jeffrey S. Morris, Kevin R. Coombes, Herbert A. Fritsche, Charlotte Clarke, Jeng-Neng Chen, Keith A. Baggerly, Lian-Chun Xiao, Mien-Chie Hung, Henry M. Kuerer

Jeffrey S. Morris

Background: Recently, researchers have been using mass spectroscopy to study cancer. For use of proteomics spectra in a clinical setting, stringent quality-control procedures will be needed.

Methods: We pooled samples of nipple aspirate fluid from healthy breasts and breasts with cancer to prepare a control sample. Aliquots of the control sample were used on two spots on each of three IMAC ProteinChip® arrays (Ciphergen Biosystems, Inc.) on 4 successive days to generate 24 SELDI spectra. In 36 subsequent experiments, the control sample was applied to two spots of each ProteinChip array, and the resulting spectra were analyzed to determine how …

Multiple Luteinizing Hormone Receptor (Lhr) Protein Variants, Interspecies Reactivity Of Anti-Lhr Mab Clone 3b5, Subcellular Localization Of Lhr In Human Placenta, Pelvic Floor And Brain, And Possible Role For Lhr In The Development Of Abnormal Pregnancy, Pelvic Floor Disorders And Alzheimer's Disease, A Bukovsky, K Indrapichate, H Fujiwara, Maria Cekanova Ms, Rndr, Phd, Me Ayala, R Dominguez, Mr Caudle, J Wimalsena, Rf Elder, P Copas, Jf Foster, Ri Fernando, Dc Henley, Nb Upadhyaya

Maria Cekanova MS, RNDr, PhD

Distinct luteinizing hormone receptor (LHR) protein variants exist due to the posttranslational modifications. Besides ovaries, LHR immunoreactivity (LHRI) was also found in other tissues, such as the brain, fallopian tube, endometrium, trophoblast and resident tissue macrophages. The 3B5 mouse monoclonal antibody was raised against purified rat LHR. In rat, porcine and human ovaries, the 3B5 identified six distinct LHR bands migrating at approximately 92, 80, 68, 59, 52 and 48 kDa. Characteristic LHRI was detected in rat, human and porcine corpora lutea. During cellular differentiation, subcellular LHR distribution changed from none to granular cytoplasmic, perinuclear, surface, nuclear and no staining. …

A Comprehensive Approach To The Analysis Of Maldi-Tof Proteomics Spectra From Serum Samples., Keith A. Baggerly, Jeffrey S. Morris, Jing Wang, David Gold, Lian-Chun Xiao, Kevin R. Coombes

Jeffrey S. Morris

For our analysis of the data from the First Annual Proteomics Data Mining Conference, we attempted to discriminate between 24 disease spectra (group A) and 17 normal spectra (group B). First, we processed the raw spectra by (i) correcting for additive sinusoidal noise (periodic on the time scale) affecting most spectra, (ii) correcting for the overall baseline level, (iii) normalizing, (iv) recombining fractions, and (v) using variable- width windows for data reduction. Also, we identified a set of polymeric peaks (at multiples of 180.6 Da) that is present in several normal spectra (B1–B8). After data processing, we found the intensities …

Bayesian Shrinkage Estimation Of The Relative Abundance Of Mrna Transcripts Using Sage, Jeffrey S. Morris, Keith A. Baggerly, Kevin R. Coombes

Jeffrey S. Morris

Serial analysis of gene expression (SAGE) is a technology for quantifying gene expression in biological tissue that yields count data that can be modeled by a multinomial distribution with two characteristics: skewness in the relative frequencies and small sample size relative to the dimension. As a result of these characteristics, a given SAGE sample may fail to capture a large number of expressed mRNA species present in the tissue. Empirical estimators of mRNA species’ relative abundance effectively ignore these missing species, and as a result tend to overestimate the abundance of the scarce observed species comprising a vast majority of …

Expression And Localization Of Estrogen Receptor-Alpha Protein In Normal And Abnormal Term Placentae And Stimulation Of Trophoblast Differentiation By Estradiol, A Bukovsky, Maria Cekanova Ms, Rndr, Phd, Mr Caudle, J Wimalasena, Js Foster, Dc Henley, Rf Elder

Maria Cekanova MS, RNDr, PhD

Estrogens play an important role in the regulation of placental function, and 17-beta-estradiol (E2) production rises eighty fold during human pregnancy. Although term placenta has been found to specifically bind estrogens, cellular localization of estrogen receptor alpha (ER-alpha) in trophoblast remains unclear. We used western blot analysis and immunohistochemistry with h-151 and ID5 monoclonal antibodies to determine the expression and cellular localization of ER-alpha protein in human placentae and cultured trophoblast cells. Western blot analysis revealed a ~65 kDa ER-alpha band in MCF-7 breast carcinoma cells (positive control). A similar band was detected in five normal term placentae exhibiting strong …

Placental Expression Of Estrogen Receptor Beta And Its Hormone Binding Variant – Comparison With Estrogen Receptor Alpha And A Role For Estrogen Receptors In Asymmetric Division And Differentiation Of Estrogen-Dependent Cells, Antonin Bukovsky, Michael R. Caudle, Maria Cekanova Ms, Rndr, Phd, Romaine I. Fernando, Jay Wimalasena, James S. Foster, Donald C. Henley, Robert F. Elder

Maria Cekanova MS, RNDr, PhD

During human pregnancy, the production of 17-beta-estradiol (E2) rises steadily to eighty fold at term, and placenta has been found to specifically bind estrogens. We have recently demonstrated the expression of estrogen receptor alpha (ER-alpha) protein in human placenta and its localization in villous cytotrophoblast (CT), vascular pericytes, and amniotic fibroblasts. In vitro, E2 stimulated development of large syncytiotrophoblast (ST) aggregates. In the present study we utilized ER-beta affinity purified polyclonal (N19:sc6820) and ER-alpha monoclonal (clone h-151) antibodies. Western blot analysis revealed a single ~52 kDa ER-beta band in chorionic villi (CV) protein extracts. In CV, strong cytoplasmic ER-beta immunoreactivity …

Variability Of Placental Expression Of Cyclin E Low Molecular Weight Variants, A Bukovsky, Maria Cekanova Ms, Rndr, Phd, Mr Caudle, J Wimalasena, Js Foster, Ja Keenan, Rf Elder

Maria Cekanova MS, RNDr, PhD

No abstract provided.

Abnormal Expression Of P27kip1 Protein In Levator Ani Muscle Of Aging Women With Pelvic Floor Disorders – A Relationship To The Cellular Differentiation And Degeneration, Antonin Bukovsky, Pleas Copas, Michael R. Caudle, Maria Cekanova Ms, Rndr, Phd, Tamara Dassanayake, Bridgett Asbury, Stuart E. Van Meter, Robert F. Elder, Jeffrey B. Brown, Stephanie B. Cross

Maria Cekanova MS, RNDr, PhD

Background Pelvic floor disorders affect almost 50% of aging women. An important role in the pelvic floor support belongs to the levator ani muscle. The p27/kip1 (p27) protein, multifunctional cyclin-dependent kinase inhibitor, shows changing expression in differentiating skeletal muscle cells during development, and relatively high levels of p27 RNA were detected in the normal human skeletal muscles.

Methods Biopsy samples of levator ani muscle were obtained from 22 symptomatic patients with stress urinary incontinence, pelvic organ prolapse, and overlaps (age range 38–74), and nine asymptomatic women (age 31–49). Cryostat sections were investigated for p27 protein expression and type I (slow …

Protein Targeting And Translocation, Barry D. Bruce, D.A. Phoenix

Barry D. Bruce

No abstract provided.

An "Extended -10" Promoter Alone Directs The Transcription Of The Dpnii Operon Of Streptococcus Pneumoniae, Alexander G. Sabelnikov, Bill Greenberg, Sanford Lacks

Alexander G Sabelnikov

No abstract provided.

Functional Explanation And Metaphysical Individualism, Justin Schwartz

Justin Schwartz

A number of (present or former) analytical Marxists, such as Jon Elster, have argued that functional explanation has almost no place in the social sciences. (Although the discussion is framed in terms of a debate among analytical Marxists, the point is quite general, and Marxism is used for illustrative purposes.) Functional explanation accounts for what is to be explained by reference to its function; thus, sighted organism have eyes because eyes enable them to see. Elster and other critics of functional explanation argue that this pattern of explanation is inconsistent with "methodological individualism," the idea, as they understand it, that …