From Wikipedia,
the free encyclopedia.
Medical Subject Headings
(MeSH) is a huge controlled
vocabulary (or
metadata system) for the
purpose of
indexing journal articles and
books in the life sciences.
Created and updated by the
United States National Library of
Medicine (NLM), it is used by
the
Medline article database and
by NLM's catalog of book holdings.
MeSH can be browsed and downloaded
free of charge on the internet; a
printed version is published once
a year.
The vocabulary and its
supporting
informatics systems were
designed to be used both by
indexing professionals and by
medical staff with various degrees
of computer experience. Using the
vocabulary in support of database
searches with the goal of
scientific research often requires
the help of specialized subject
librarians. MeSH has a strong
clinical bent, making non-clinical
searches, such as those being done
to support epidemiological
studies, more difficult than the
norm.
The
2005 version of MeSH contains
a total of 22,568 subject
headings, also known as
descriptors. Most of these are
accompanied by a short definition,
links to related descriptors, and
a list of synonyms or very similar
terms (known as entry terms).
Because of these synonym lists,
MeSH can also be viewed as a
thesaurus.
The descriptors are arranged in
a
hierarchy. A given descriptor
may appear at several places in
the hierarchy, similar to
Wikipedia's category system.
The toplevel categories are:
- Anatomy [A]
- Organisms [B]
- Diseases [C]
- Chemicals and Drugs [D]
- Analytical, Diagnostic and
Therapeutic Techniques and
Equipment [E]
- Psychiatry and Psychology
[F]
- Biological Sciences [G]
- Physical Sciences [H]
- Anthropology, Education,
Sociology and Social Phenomena
[I]
- Technology and Food and
Beverages [J]
- Humanities [K]
- Information Science [L]
- Persons [M]
- Health Care [N]
- Geographic Locations [Z]
In addition to the descriptor
hierarchy, MeSH contains a small
number of standard qualifiers
(also known as subheadings),
which can be added to descriptors
to narrow down the topic. For
example, "Measles" is a descriptor
and "epidemology" is a qualifier;
"Measles/epidemology" describes
the subheading of epidemological
articles about Measles. The
"epidemiology" qualifier can be
added to all other disease
descriptors. Not all
descriptor/qualifier combinations
are allowed since some of them may
be meaningless. In all there are
83 different qualifiers.
In
Medline, every journal article
is indexed with some 10-15
headings or subheadings, with one
or two of them designated as
major and marked with an
asterisk. When performing a search
in Medline, entry terms are
automatically translated into the
corresponding descriptors.
Furthermore, by default all the
descriptors below the given one in
the hierarchy are included in the
search.
In addition to the descriptors,
MeSH also contains some 139,000
Supplementary Concept Records.
These do not belong to the
controlled vocabulary as such and
are not used for indexing Medline
articles; instead they enlarge the
thesaurus and contain links to the
closest fitting descriptor to be
used in a Medline search. Many of
these records describe chemical
substances.
MeSH has been translated into
numerous other languages and
allows retrieval of documents from
different languages.
