MeSH on the Web. NLM Technical Bulletin. Sep-Oct 1997

1998 MeSH Trees in ASCII Format
MeSH descriptors with the tree numbers that place the heading in a hierarchical arrangement. Sorted by tree number.

MeSH in MARC Format
MeSH vocabulary in the USMARC authority format include MeSH descriptors, qualifiers (subheadings), and descriptor-qualifier combination records. Supplementary Chemical Records are not included. For best results, please use a graphical interface.

1998 MeSH in ASCII Format
MeSH descriptors, qualifiers (subheadings), and Supplementary Chemical Records (through September 1, 1997), in ASCII format. This is a new tagged format and is similar to the ELHILL Unit Record format but the data are encoded in ASCII, not EBCDIC. This format also includes Supplementary Chemical Records, with those data through September 1, 1997. See Figure 1 below.

Figure 1 - Sample ASCII MeSH Format Record:




*NEWRECORD

RECTYPE     = D

MH          = Gene Library

PRINT ENTRY = DNA Library:T028:ACX:EQV:NLM (1998):961031:abcdef

PRINT ENTRY = Gene Bank:T028:NON:EQV:NLM (1990):890221:abcdef

ENTRY       = Bank, Gene

ENTRY       = Banks, Gene

ENTRY       = DNA Libraries

ENTRY       = Gene Banks

ENTRY       = Gene Libraries

ENTRY       = Libraries, DNA

ENTRY       = Libraries, Gene

ENTRY       = Library, DNA

ENTRY       = Library, Gene

MN          = G05.275.195

MN          = G05.331.599.110.410

FX          = DNA, Recombinant

MH_TH       = NLM (1990)

ST          = T028

AN          = do not confuse with GENOMIC LIBRARY; do not 

	      confuse X ref GENE BANK with BIOLOGICAL 

	      SPECIMEN BANKS; no qualif

PI          = Base Sequence (78-89)

PI          = Cloning, Molecular (80-89)

PI          = Plasmids (78-85)

MS          = A large collection of cloned DNA fragments 

	      from a given organism, tissue, organ, or cell 

	      type. It may contain complete genomic sequences 

	      (GENOMIC LIBRARY) or complementary DNA 

	      sequences, the latter being formed from 

	      messenger RNA and lacking intron sequences.

PM          = 90

HN          = 90

MED         = 2295

MED         = *224

M90         = 3520

M90         = *357

M85         = 253

M85         = *33

M80         = 1

CATSH       = CAT LIST

DA          = 890515

RO          = O:PXP

RO          = A:SJN

RO          = M:AGS

MR          = 970620

DC          = 1

DX          = 900101

UI          = D015723

ASCII MeSH contains all data that are present in ELHILL MeSH, including cross-references and scope notes. Online descriptions of the data elements in each file are available for each of the three record types: Descriptor Data Elements, Qualifier (subheadings) Data Elements, and Supplementary Chemical Record Data Elements. Publication Types (PT) are encoded as MeSH Descriptors even though they appear in the PT field and not the MH field in the MEDLINE citations.

Restrictions on Use

There is no charge for downloading MeSH data from the NLM Web site. However, use of the ASCII MeSH file data is subject to conditions which are detailed in the memorandum of understanding that must be completed before downloading data.

Availability

The data for Descriptors and Qualifiers are updated annually and users of the data are encouraged to obtain the new year's data.

Supplementary Chemical Records are updated in ELHILL MeSH on a daily basis and the current file in ASCII MeSH is complete through September 1, 1997. The Supplementary Chemical Records will be added to ASCII MeSH periodically. The data elements that require a descriptor MeSH heading value, such as the Heading Mapped-To (HM) element, have been updated to match a descriptor in 1998 MeSH.

MeSH Descriptors and Qualifiers are also published annually in print as the Medical Subject Headings, Annotated Alphabetic List. Some Descriptor data are also published in Medical Subject Headings, Tree Structures and Permuted Medical Subject Headings.

File Format

Each MeSH record is indicated by a separate line, preceding the record, consisting of the string: *NEWRECORD. (See Figure 1 on this page.) Each element or occurrence is contained on a single line. Each line contains an element name and value, for example, MH = Appendicitis. The same is true for longer, free-text fields such the Annotation and Scope Note. (The longest occurrence/line in the 1998 files is in the descriptor file and is 1160 characters.)

For data elements that are multiply-occurring, each element occurs on a separate line, for example, the MeSH Tree Number:

MN = E05.909.262.607.790

MN = E05.909.262.620.670.620

Generally, data in ASCII MeSH files are in 7-bit ASCII format. The only exception is that in 41 descriptor records, the Annotation element contains one or more diacritical characters. No attempt was made to translate these characters so they may appear differently in different displays.

The file extensions are .bin rather than .txt so that Web browsers will prompt to save rather than automatically trying to display the relatively large text files (up to 36MB). The binary download should have no adverse effects for most users. The lines will usually be transmitted with only a line feed character (decimal 10) and not also a carriage return (decimal 13). Please contact the MeSH Section at the address given in Questions and Assistance at the end of this article if you have questions.

Numbers of Records in the 1998 MeSH

The number of records in the file for the three record types are shown below.


Record Type                           Total Records



Descriptors (MeSH headings, 

   including Publication Types)              18,934

Qualifiers (subheadings)                        787

Supplementary Chemical Records              *95,617



   * through September 1, 1997

Additional 1998 MeSH Files Available

1998. Pharmacologic Actions of a given drug

1998. Drugs with a given Pharmacologic Action

1998 New Headings with Scope Notes
Main headings that are new in 1998 with scope notes (definitions), cross-references, and other information.

Sample Entry:

Amino Acid Substitution
The naturally occurring or experimentally induced replacement of one or more amino acids in a protein with another. If a functionally equivalent amino acid is substituted, the protein may retain wild-type activity. Substitution may also diminish or eliminate protein function. Experimentally induced substitution is often used to study enzyme activities and binding site properties.