Theodore R. Pak

Dr. Theodore R. Pak

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Research Focus & Metrics

Academic Career Length

20Years (2007-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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18 July 2012 in Nature
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Journal Article
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OROrit Rozenblatt-Rosen
Orit Rozenblatt-Rosen
RDRahul C. Deo
Rahul C. Deo
MPMegha Padi
Megha Padi
GAGuillaume Adelmant
Guillaume Adelmant
MCMichael A. Calderwood
Michael A. Calderwood
MVMarc Vidal
Marc Vidal
Combining analysis of host proteome and transcriptome perturbations induced by tumour virus proteins with ongoing genome-wide studies of cancer facilitates the prioritization of cancer genes. This systematic search for host targets of tumour viruses, using proteome and transcriptome analyses of viral proteins from mammalian DNA viruses with transforming or tumorigenic properties, provides an extensive catalogue of changes in genetic and protein expression that can be screened against genome-wide studies of cancer. The study focuses on human papillomavirus, Epstein–Barr virus, adenovirus and polyomavirus. The resulting list of transforming viral protein targets identifies causal genes within both somatic and Mendelian cancer-associated loci. Genotypic differences greatly influence susceptibility and resistance to disease. Understanding genotype–phenotype relationships requires that phenotypes be viewed as manifestations of network properties, rather than simply as the result of individual genomic variations1. Genome sequencing efforts have identified numerous germline mutations, and large numbers of somatic genomic alterations, associated with a predisposition to cancer2. However, it remains difficult to distinguish background, or ‘passenger’, cancer mutations from causal, or ‘driver’, mutations in these data sets. Human viruses intrinsically depend on their host cell during the course of infection and can elicit pathological phenotypes similar to those arising from mutations3. Here we test the hypothesis that genomic variations and tumour viruses may cause cancer through related mechanisms, by systematically examining host interactome and transcriptome network perturbations caused by DNA tumour virus proteins. The resulting integrated viral perturbation data reflects rewiring of the host cell networks, and highlights pathways, such as Notch signalling and apoptosis, that go awry in cancer. We show that systematic analyses of host targets of viral proteins can identify cancer genes with a success rate on a par with their identification through functional genomics and large-scale cataloguing of tumour mutations. Together, these complementary approaches increase the specificity of cancer gene identification. Combining systems-level studies of pathogen-encoded gene products with genomic approaches will facilitate the prioritization of cancer-causing driver genes to advance the understanding of the genetic basis of human cancer.

31 October 2007 in Genome Research
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Journal Article
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MLMatthieu Legendre
Matthieu Legendre
NPNathalie Pochet
Nathalie Pochet
TPTheodore R. Pak
Theodore R. Pak
KVKevin Verstrepen
Kevin Verstrepen
Variable tandem repeats are frequently used for genetic mapping, genotyping, and forensics studies. Moreover, variation in some repeats underlies rapidly evolving traits or certain diseases. However, mutation rates vary greatly from repeat to repeat, and as a consequence, not all tandem repeats are suitable genetic markers or interesting unstable genetic modules. We developed a model, “SERV,” that predicts the variability of a broad range of tandem repeats in a wide range of organisms. The nonlinear model uses three basic characteristics of the repeat (number of repeated units, unit length, and purity) to produce a numeric “VARscore” that correlates with repeat variability. SERV was experimentally validated using a large set of different artificial repeats located in theSaccharomyces cerevisiae URA3gene. Further in silico analysis shows that SERV outperforms existing models and accurately predicts repeat variability in bacteria and eukaryotes, including plants and humans. Using SERV, we demonstrate significant enrichment of variable repeats within human genes involved in transcriptional regulation, chromatin remodeling, morphogenesis, and neurogenesis. Moreover, SERV allows identification of known and candidate genes involved in repeat-based diseases. In addition, we demonstrate the use of SERV for the selection and comparison of suitable variable repeats for genotyping and forensic purposes. Our analysis indicates that tandem repeats used for genotyping should have a VARscore between 1 and 3. SERV is publicly available fromhttp://hulsweb1.cgr.harvard.edu/SERV/.

1 August 2018 in Molecular Systems Biology
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Journal Article
Open access
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DMDaniela Michlmayr
Daniela Michlmayr
TPTheodore R. Pak
Theodore R. Pak
ARAdeeb H Rahman
Adeeb H Rahman
EAEl‐Ad David Amir
El‐Ad David Amir
EKEun-Young Kim
Eun-Young Kim
EHEva Harris
Eva Harris
Chikungunya virus (CHIKV) is a mosquito‐borne alphavirus that causes global epidemics of debilitating disease worldwide. To gain functional insight into the host cellular genes required for virus infection, we performed whole‐blood RNA‐seq, 37‐plex mass cytometry of peripheral blood mononuclear cells (PBMCs), and serum cytokine measurements of acute‐ and convalescent‐phase samples obtained from 42 children naturally infected with CHIKV. Semi‐supervised classification and clustering of single‐cell events into 57 sub‐communities of canonical leukocyte phenotypes revealed a monocyte‐driven response to acute infection, with the greatest expansions in “intermediate” CD14 ++ CD16 + monocytes and an activated subpopulation of CD14 + monocytes. Increases in acute‐phase CHIKV envelope protein E2 expression were highest for monocytes and dendritic cells. Serum cytokine measurements confirmed significant acute‐phase upregulation of monocyte chemoattractants. Distinct transcriptomic signatures were associated with infection timepoint, as well as convalescent‐phase anti‐CHIKV antibody titer, acute‐phase viremia, and symptom severity. We present a multiscale network that summarizes all observed modulations across cellular and transcriptomic levels and their interactions with clinical outcomes, providing a uniquely global view of the biomolecular landscape of human CHIKV infection.

1 October 2018 in Infection and Immunity
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Journal Article
Open access
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DADeena R. Altman
Deena R. Altman
MSMitchell J. Sullivan
Mitchell J. Sullivan
KCKieran I. Chacko
Kieran I. Chacko
DBDivya Balasubramanian
Divya Balasubramanian
TPTheodore R. Pak
Theodore R. Pak
HBHarm van Bakel
Harm van Bakel
Therapy for bacteremia caused by Staphylococcus aureus is often ineffective, even when treatment conditions are optimal according to experimental protocols. Adapted subclones, such as those bearing mutations that attenuate agr -mediated virulence activation, are associated with persistent infection and patient mortality.

2 August 2023 in Clinical Infectious Diseases
Verified
Journal Article
Closed access
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TPTheodore R. Pak
Theodore R. Pak
JYJessica Young
Jessica Young
CMCaroline S McKenna
Caroline S McKenna
AAAnna Agan
Anna Agan
LDLaura DelloStritto
Laura DelloStritto
MKMichael Klompas
Michael Klompas
Background: Influential studies conclude that each hour until antibiotics increases mortality in sepsis. However, these analyses often (1) adjusted for limited covariates, (2) included patients with long delays until antibiotics, (3) combined sepsis and septic shock, and (4) used linear models presuming each hour delay has equal impact. We evaluated the effect of these analytic choices on associations between time-to-antibiotics and mortality. Methods: We retrospectively identified 104 248 adults admitted to 5 hospitals from 2015–2022 with suspected infection (blood culture collection and intravenous antibiotics ≤24 h of arrival), including 25 990 with suspected septic shock and 23 619 with sepsis without shock. We used multivariable regression to calculate associations between time-to-antibiotics and in-hospital mortality under successively broader confounding-adjustment, shorter maximum time-to-antibiotic intervals, stratification by illness severity, and removing assumptions of linear hourly associations. Results: Changing covariates, maximum time-to-antibiotics, and severity stratification altered the magnitude, direction, and significance of observed associations between time-to-antibiotics and mortality. In a fully adjusted model of patients treated ≤6 hours, each hour was associated with higher mortality for septic shock (adjusted odds ratio [aOR]: 1.07; 95% CI: 1.04–1.11) but not sepsis without shock (aOR: 1.03; .98–1.09) or suspected infection alone (aOR: .99; .94–1.05). Modeling each hour separately confirmed that every hour of delay was associated with increased mortality for septic shock, but only delays >6 hours were associated with higher mortality for sepsis without shock. Conclusions: Associations between time-to-antibiotics and mortality in sepsis are highly sensitive to analytic choices. Failure to adequately address these issues can generate misleading conclusions.

6 August 2015 in Clinical Infectious Diseases
Verified
Journal Article
Open access
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TPTheodore R. Pak
Theodore R. Pak
AKAndrew Kasarskis
Andrew Kasarskis
Recent reviews have examined the extent to which routine next-generation sequencing (NGS) on clinical specimens will improve the capabilities of clinical microbiology laboratories in the short term, but do not explore integrating NGS with clinical data from electronic medical records (EMRs), immune profiling data, and other rich datasets to create multiscale predictive models. This review introduces a range of “omics” and patient data sources relevant to managing infections and proposes 3 potentially disruptive applications for these data in the clinical workflow. The combined threats of healthcare-associated infections and multidrug-resistant organisms may be addressed by multiscale analysis of NGS and EMR data that is ideally updated and refined over time within each healthcare organization. Such data and analysis should form the cornerstone of future learning health systems for infectious disease.