Evaluated Medlineby Matthew Cockerill
(Issue 10 · posted June 13, 1997; archived June 27, 1997)
The Original MEDLINE
MEDLINE is a database of more than eight million bibliographic references from the medical and biological research literature. Compiled and maintained by the National Library of Medicine (NLM) at the National Institutes of Health in Bethesda, Maryland, MEDLINE pulls together and organizes abstracts from more than 3,800 journals from 1966 to the present.
The applications of MEDLINE are myriad. Researchers find it a quick means to track down the latest findings by their peers, while clinicians use it to ensure that their diagnoses and treatment strategies are supported by the medical literature. And for students, of course, it is an invaluable aid to coursework and research.
MEDLINE distinguishes itself from other bibliographic databases in that all of its entries have been classified using a controlled vocabulary of terms known as Medical Subject Headings, or MeSH terms. MeSH terms make it possible to restrict searches in very specific ways that would be difficult or impossible to accomplish using standard free-text searching. For example, using MeSH terms relating to methodology, it is possible to restrict searches to cover only controlled clinical trials. The better defined the parameters of a search, the more useful its results.
Second and Third Generation MEDLINE: Entrez and PubMed
Until recently, most researchers accessed MEDLINE either on a CD-ROM or via a dialup service such as the NLM's own Grateful Med. While useful, these systems were expensive, and could be quite slow to use.
In the early 1990s, the National Council for Biotechnology Information (NCBI), a subdivision of the NLM, launched Entrez, an Internet service that combined a searchable molecular biology subset of MEDLINE with links to protein and nucleotide sequence databases. A novel clustering algorithm also made it possible to link from one MEDLINE record to similar entries in MEDLINE using common keyword content.
Entrez was an important advance beyond its predecessors, and quickly became
one of the first truly indispensable Web resources for biology
researchers. It was free, and most importantly, it was extremely fast. Its drawback,
a major one, was that
it only offered partial MEDLINE coverage. So in 1996 the NCBI launched
PubMed, which extended
the reach of Entrez to cover everything on MEDLINE, and even material beyond.
In addition to making all of MEDLINE globally available free of charge,
the PubMed project helps keep MEDLINE up to date by accepting abstract
information from publishers in electronic format. These abstracts are promptly made
available on PubMed before MeSH terms are added, and before they are entered into
MEDLINE itself. Whenever possible, these abstracts are linked to their
corresponding full-text articles at the publishers' sites.
For other MEDLINE providers, trying to compete with PubMed's free and
comprehensive services has proven challenging. Several Web sites
(e.g., Healthgate, Medscape) now offer a free MEDLINE service of some kind.
But these generally
cannot compare in speed or usefulness with PubMed. Other providers, such
as SilverPlatter, offer features that PubMed does not, but a high premium
is charged for the service.
Fourth Generation: BioMedNet's Evaluated MEDLINE
Now there is a real alternative. BioMedNet's new Evaluated MEDLINE offers a collection of features well beyond the scope of those offered by PubMed, but the service remains free for all BioMedNet members.
In BioMedNet's Evaluated MEDLINE, MEDLINE's 3,800-plus journals are organized into a hierarchical table of contents, allowing journal issues to be browsed in one fell swoop. This method eliminates a major problem found with most online search techniques, which is that because they favor searching over browsing, they mitigate against the serendipitous discovery of relevant papers. This browse feature is also very useful in tracking down papers when all the searcher knows is the journal name and the approximate date when the paper appeared. The Medical Subject Heading hierarchy can be browsed in a similar fashion, and any MeSH term found in this way can be used to restrict future searches.
Every word in Evauated MEDLINE is indexed, so phrases such as Vitamin A are correctly identified. Most other MEDLINE services, even PubMed, fail at this kind of search because their search engine technology cannot index words as common as A. Evaluated MEDLINE, however, using Electronic Press's new Bibliotek 2.0 technology, can search every single word in the whole of MEDLINE in a matter of seconds.
Evaluated MEDLINE creates a personal search history for each BioMedNet member who makes use of the service. The search history stays in the system from one session to the next, allowing previous searches to be combined and refined with additional search terms. Search results can easily be downloaded in a format suitable for bibliographic management software. And since Evaluated MEDLINE is part of BioMedNet, which has its own extensive online library of full-text journals, there are of course links from Evaluated MEDLINE to those full-text articles wherever possible.
The Evaluation Process
But the greatest innovation found in Evaluated MEDLINE is the
evaluations themselves, which are drawn from the highly respected
biological and medical Current Opinion review journals, published by Current
Biology, Ltd. and Rapid Science, Ltd.,
respectively.
Current Opinion journals cover a range of disciplines. Among the
biology Current Opinion journals, for example, one will find Current
Opinion in Biotechnology, Current Opinion in Cell Biology, Current
Opinion in Neurobiology, etc. Each journal covers the same broad themes
from one year to the next - Current Opinion in Biotechnology, for
example, will devote one issue per year to analytical biotechnology,
another to biochemical engineering and plant biotechnology, etc. So for
each issue's reviews, the authors are asked to focus on advances in
their area in the past year, and references for each review will be
predominantly to the past year's literature.
Current Opinion review authors are asked,
when preparing their references, to select those that they consider "Of
Special Interest" or "Of Outstanding Interest"; such references are
assigned one or two stars, respectively. The authors also provide a
short explanation of the particular contribution of each paper
highlighted in this way. In Evaluated MEDLINE, these evaluations are
then associated with the MEDLINE entries of the relevant references.
Both the evaluation and the accompanying comments are displayed with the
results of a search, giving the user valuable clues as to which of many
matching references are likely to be the most informative. It is also
possible to follow links back to the citing article, providing a
convenient way to jump from a relevant article to a review covering the
field concerned.
According to Peter Newmark, Managing Director of Current Biology, Ltd., "Evaluated MEDLINE makes excellent use of the evaluations included in the Current Opinion journals. It helps scientists to quickly identify the most relevant information in the literature, which has always been the goal of the Current Opinion journals." By combining the guidance found in Current Opinion journals with the search capabilities of MEDLINE, BioMedNet's Evaluated MEDLINE provides a service that is unique in scientific research.
Matthew Cockerill is Editor of BioMedNet, where he is responsible for acquisition of biological databases.
Andrzej Krauze is an illustrator, poster maker, cartoonist, and painter who illustrates regularly for HMS Beagle, The Guardian, The Sunday Telegraph, Bookseller and New Statesman.
