OpCitance: Citation contexts identified from the PubMed Central open access articles.

OpCitance contains all the sentences from 2 million PubMed Central open-access (PMCOA) articles, with 137 million inline citations annotated (i.e., the "citation contexts").

The Citation Cloud of a biomedical article: a free, public, web-based tool enabling citation analysis.

Background: An article's citations are useful for finding related articles that may not be readily found by keyword searches or textual similarity. Citation analysis is also important for analyzing scientific innovation and the structure of the biomedical literature. We wanted to facilitate citation analysis for the broad community by providing a user-friendly interface for accessing and analyzing citation data for biomedical articles.

Building a PubMed knowledge graph.

PubMed is an essential resource for the medical domain, but useful concepts are either difficult to extract or are ambiguous, which has significantly hindered knowledge discovery. To address this issue, we constructed a PubMed knowledge graph (PKG) by extracting bio-entities from 29 million PubMed abstracts, disambiguating author names, integrating funding data through the National Institutes of Health (NIH) ExPORTER, collecting affiliation history and educational background of authors from ORCID, and identifying fine-grained affiliation data from MapAffil. Through the integration of these credible multi-source data, we could create connections among the bio-entities, authors, articles, affiliations, and funding.

Geographical Distribution of Biomedical Research in the USA and China.

We analyze nearly 20 million geocoded PubMed articles with author affiliations. Using K-means clustering for the lower 48 US states and mainland China, we find that the average published paper is within a relatively short distance of a few centroids. These centroids have shifted very little over the past 30 years, and the distribution of distances to these centroids has not changed much either.

Self-citation is the hallmark of productive authors, of any gender.

It was recently reported that men self-cite >50% more often than women across a wide variety of disciplines in the bibliographic database JSTOR. Here, we replicate this finding in a sample of 1.6 million papers from Author-ity, a version of PubMed with computationally disambiguated author names.

Spatiotemporal analysis of tropical disease research combining Europe PMC and affiliation mapping web services.

Background: Tropical medicine appeared as a distinct sub-discipline in the late nineteenth century, during a period of rapid European colonial expansion in Africa and Asia. After a dramatic drop after World War II, research on tropical diseases have received more attention and research funding in the twenty-first century.

Methods: We used Apache Taverna to integrate Europe PMC and MapAffil web services, containing the spatiotemporal analysis workflow from a list of PubMed queries to a list of publication years and author affiliations geoparsed to latitudes and longitudes.

Predicting MeSH Beyond MEDLINE.

Medical subject headings (MeSH) are a flexible and useful tool for describing biomedical concepts. Here, we present MeSHier, a tool for assigning MeSH terms to biomedical documents based on abstract similarity and references to MEDLINE records. When applied to PubMedCentral papers, NIH grants, and USPTO patents we find that these two sources of information produce largely disjoint sets of related MEDLINE records, albeit with some overlap in MeSH.

Quantifying Conceptual Novelty in the Biomedical Literature.

We introduce several measures of novelty for a scientific article in MEDLINE based on the temporal profiles of its assigned Medical Subject Headings (MeSH). First, temporal profiles for all MeSH terms (and pairs of MeSH terms) were characterized empirically and modelled as logistic growth curves. Second, a paper's novelty is captured by its youngest MeSH (and pairs of MeSH) as measured in years and volume of prior work.

Kin of coauthorship in five decades of health science literature.

Family background-kinship-can propagate careers. The evidence for academic nepotism is littered with complex associations and disputed causal inferences. Surname clustering, albeit with very careful consideration of surnames' flows across regions and time periods, can be used to reflect family ties.

MapAffil: A Bibliographic Tool for Mapping Author Affiliation Strings to Cities and Their Geocodes Worldwide.

Bibliographic records often contain author affiliations as free-form text strings. Ideally one would be able to automatically identify all affiliations referring to any particular country or city such as Saint Petersburg, Russia. That introduces several major linguistic challenges.

Has large-scale named-entity network analysis been resting on a flawed assumption?

The assumption that a name uniquely identifies an entity introduces two types of errors: splitting treats one entity as two or more (because of name variants); lumping treats multiple entities as if they were one (because of shared names). Here we investigate the extent to which splitting and lumping affect commonly-used measures of large-scale named-entity networks within two disambiguated bibliographic datasets: one for co-author names in biomedicine (PubMed, 2003-2007); the other for co-inventor names in U.S.

MicroRNA expression in rat brain exposed to repeated inescapable shock: differential alterations in learned helplessness vs. non-learned helplessness.

MicroRNA (miRNA) expression was measured within frontal cortex of male Holtzman rats subjected to repeated inescapable shocks at days 1 and 7, tested for learned helplessness (LH) at days 2 and 8, and sacrificed at day 15. We compared rats that did vs. did not exhibit LH, as well as rats that were placed in the apparatus and tested for avoidance but not given shocks (tested controls, TC).

Olfactory discrimination training up-regulates and reorganizes expression of microRNAs in adult mouse hippocampus.

Adult male mice (strain C57Bl/6J) were trained to execute nose-poke responses for water reinforcement; then they were randomly assigned to either of two groups: olfactory discrimination training (exposed to two odours with reward contingent upon correctly responding to one odour) or pseudo-training (exposed to two odours with reward not contingent upon response). These were run in yoked fashion and killed when the discrimination-trained mouse reached a learning criterion of 70% correct responses in 20 trials, occurring after three sessions (a total of approximately 40 min of training). The hippocampus was dissected bilaterally from each mouse (N = 7 in each group) and profiling of 585 miRNAs (microRNAs) was carried out using multiplex RT-PCR (reverse transcription-PCR) plates.

Author Name Disambiguation in MEDLINE.

BACKGROUND: We recently described "Author-ity," a model for estimating the probability that two articles in MEDLINE, sharing the same author name, were written by the same individual. Features include shared title words, journal name, coauthors, medical subject headings, language, affiliations, and author name features (middle initial, suffix, and prevalence in MEDLINE). Here we test the hypothesis that the Author-ity model will suffice to disambiguate author names for the vast majority of articles in MEDLINE.

Arrowsmith two-node search interface: a tutorial on finding meaningful links between two disparate sets of articles in MEDLINE.

The Arrowsmith two-node search is a strategy that is designed to assist biomedical investigators in formulating and assessing scientific hypotheses. More generally, it allows users to identify biologically meaningful links between any two sets of articles A and C in PubMed, even when these share no articles or authors in common and represent disparate topics or disciplines. The key idea is to relate the two sets of articles via title words and phrases (B-terms) that they share.

Natural antisense transcripts are co-expressed with sense mRNAs in synaptoneurosomes of adult mouse forebrain.

Natural antisense transcripts and overlapping sense transcripts are expressed in a variety of tissues, including adult mouse brain. Here we show that a subset of mRNA-like sense-antisense transcript pairs are co-expressed within synaptoneurosomes of adult mouse forebrain, a subcellular fraction that is enriched in pinched-off dendritic spines of pyramidal neurons. Several of these pairs involve mRNAs that have been implicated in synaptic functions and in Alzheimer disease pathways.

Expression of microRNAs and their precursors in synaptic fractions of adult mouse forebrain.

We have characterized the expression of microRNAs and selected microRNA precursors within several synaptic fractions of adult mouse forebrain, including synaptoneurosomes, synaptosomes and isolated post-synaptic densities (PSDs), using methods of microRNA microarray, real time qRT-PCR, Northern blotting and immunopurification using anti-PSD95 antibody. The majority of brain microRNAs (especially microRNAs known to be expressed in pyramidal neurons) are detectably expressed in synaptic fractions, and a subset of microRNAs is significantly enriched in synaptic fractions relative to total forebrain homogenate. MicroRNA precursors are also detectable in synaptic fractions at levels that are comparable to whole tissue.

Anne O'Tate: A tool to support user-driven summarization, drill-down and browsing of PubMed search results.

Background: PubMed is designed to provide rapid, comprehensive retrieval of papers that discuss a given topic. However, because PubMed does not organize the search output further, it is difficult for users to grasp an overview of the retrieved literature according to non-topical dimensions, to drill-down to find individual articles relevant to a particular individual's need, or to browse the collection.

Results: In this paper, we present Anne O'Tate, a web-based tool that processes articles retrieved from PubMed and displays multiple aspects of the articles to the user, according to pre-defined categories such as the "most important" words found in titles or abstracts; topics; journals; authors; publication years; and affiliations.

A quantitative model for linking two disparate sets of articles in MEDLINE.

Background: Identifying information that implicitly links two disparate sets of articles is a fundamental and intuitive data mining strategy that can help investigators address real scientific questions. The Arrowsmith two-node search finds title words and phrases (so-called B-terms) that are shared across two sets of articles within MEDLINE and displays them in a manner that facilitates human assessment. A serious stumbling-block has been the lack of a quantitative model for predicting which of the hundreds if not thousands of B-terms computed for a given search are most likely to be relevant to the investigator.

ADAM: another database of abbreviations in MEDLINE.

Motivation: Abbreviations are an important type of terminology in the biomedical domain. Although several groups have already created databases of biomedical abbreviations, these are either not public, or are not comprehensive, or focus exclusively on acronym-type abbreviations. We have created another abbreviation database, ADAM, which covers commonly used abbreviations and their definitions (or long-forms) within MEDLINE titles and abstracts, including both acronym and non-acronym abbreviations.

Complications in mammalian microRNA target prediction.

In this chapter, we review evidence that at least three different types of microRNA (miRNA)-messenger RNA (mRNA) target interactions exist in mammals: short seeds, long seeds, and "perfect" hits (allowing G:U matches). Because new types of miRNAs are still being discovered, this list may not yet be complete.

Alu elements within human mRNAs are probable microRNA targets.

Recently, we reported that four microRNAs show perfect complementarity with MIR/LINE-2 elements within human mRNAs. This finding raises the question of whether microRNAs might also target other genomic repeats and transposable elements. Here, we demonstrate that almost 30 human microRNAs exhibit typical short-seed complementarity with a specific site within Alu elements that is highly conserved within 3' untranslated regions of human mRNAs.

Collaborative development of the Arrowsmith two node search interface designed for laboratory investigators.

Arrowsmith is a unique computer-assisted strategy designed to assist investigators in detecting biologically-relevant connections between two disparate sets of articles in Medline. This paper describes how an inter-institutional consortium of neuroscientists used the UIC Arrowsmith web interface http://arrowsmith.psych.

Mammalian microRNAs derived from genomic repeats.

In this article, we show that a subset of conventional mammalian microRNAs is derived from LINE-2 transposable elements and other genome repeats. These repeat-derived microRNAs arise from conventional precursor hairpins and are distinct from the rasiRNAs, which appear to be processed from long double-stranded RNA precursors. The insertion of transposable elements into new genomic sites appears to be one of the driving-forces that create new microRNAs during mammalian evolution.