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October 26, 2015 - Updated Label List and NLM Category Mappings File:

The Updated Label List and NLM Category Mappings file records 3,032 labels: 2,799 (from the
2014 Label List), and 233 new labels. Each label has a map to one of five corresponding broader NLM Categories (i.e., BACKGROUND, OBJECTIVE, METHODS, RESULTS, or CONCLUSIONS) and an indication of whether the label is classed as an "Ending Label" concept. The 233 new labels have a timestamp of "|20151026". This file does not contain labels that map to UNASSIGNED as an NLM Category (see explanation).

The updated file has the same format as the November 13, 2014 update and is available from the Downloads page.



November 13, 2014 - Updated Label List and NLM Category Mappings File:

The Updated Label List and NLM Category Mappings file records 2,799 labels: 2,454 (from the
2013 Label List), and 345 new labels. Each label has a map to one of five corresponding broader NLM Categories (i.e., BACKGROUND, OBJECTIVE, METHODS, RESULTS, or CONCLUSIONS) and an indication of whether the label is classed as an "Ending Label" concept. The 345 new labels have a timestamp of "|20141113". This file does not contain labels that map to UNASSIGNED as an NLM Category (see explanation).

The updated file has the same format as the November 6, 2013 update and is available from the Downloads page.



November 6, 2013 - Updated Label List and NLM Category Mappings File:

The Updated Label List and NLM Category Mappings file records 2,454 labels: 1,949 (from the
2012 Label List), and 505 new labels. Each label has a map to one of five corresponding broader NLM Categories (i.e., BACKGROUND, OBJECTIVE, METHODS, RESULTS, or CONCLUSIONS) and an indication of whether the label is classed as an "Ending Label" concept. The 505 new labels have a timestamp of "|20131106". This file does not contain labels that map to UNASSIGNED as an NLM Category (see explanation).

The updated file has the same format as the August 31, 2012 update and is available from the Downloads page.



August 31, 2012 - Updated Label List and NLM Category Mappings File:

The Updated Label List and NLM Category Mappings file records 1,949 labels: 1,645 from the August 26, 2011 update, and 304 new labels. Each label has a corresponding broader NLM Category map, and an indication of whether the label is classed as an "Ending Label" concept. The 304 new labels have a timestamp of "|20120831".

The updated file has the same format as the August 26, 2011 update and is available from the
Downloads page.



August 26, 2011 - Updated Label List and NLM Category Mappings File:

The Updated Label List and NLM Category Mappings file records 1,645 labels: 1,456 original labels (from the 2011 Label List) and 189 new labels. Each label has a corresponding broader NLM Category map, and an indication of whether the label is classed as an "Ending Label" concept. The original 1,456 label entries have a timestamp of "|20100629". The new 189 label entries have a timestamp of "|20110825".

The updated file has a new format and includes both original and new entries. The updated file is available from the
Downloads page.

The format is a bar separated ASCII text list having four columns on each line.

STRUCTURED ABSTRACT LABEL | NLM CATEGORY | ENDING LABEL CONCEPT (Y/N) | TIMESTAMPYYYYMMDD



2011 Label List and NLM Category Mappings File:

The 2011 Label List and NLM Category Mappings file records 1,456 values determined to be Structured Abstract labels that were used in the
2011 NLMMedlineCitationSet DTD and MEDLINE/PubMed XML. Each label has a corresponding broader NLM Category map, and an indication of whether the label is classed as an "Ending Label" concept. This file is available from the Downloads page.

The format is a bar separated ASCII text list having three columns:

STRUCTURED ABSTRACT LABEL | NLM CATEGORY | ENDING LABEL CONCEPT (Y/N)

Column 1: STRUCTURED ABSTRACT LABEL

Contains structured abstract labels identified from the 2010 MEDLINE Baseline and the MEDLINE daily files from November 24, 2009 to June 2, 2010 that have PMID counts of 25 or more PMIDs per label as well as some with fewer than 25 PMIDs because they were straightforward maps. These 1,456 entries account for 98.50% (6,674,229 of the 6,775,741 of total instances) of possible structured abstract labels identified in the data. There remains an extremely long tail of structured abstract labels with instances of 24 or fewer PMIDs. Evaluation and mapping of labels work continues at NLM; more values will be available for the 2012 MEDLINE Baseline.

Column 2: NLM CATEGORY

Contains the NLM Category which is one of five broad conceptual groups, or Metacategories, to which each structured abstract label was mapped. The five are: BACKGROUND, OBJECTIVE, METHODS, RESULTS, CONCLUSIONS.

For researchers or implementers who want to use these NLM Categories, NLM offers the following ranking guideline based on our indexing experience on the value of the section of the abstract in identifying pertinent main subject concepts discussed in the article:

1) OBJECTIVE
2) CONCLUSIONS
3) RESULTS
4) METHODS
5) BACKGROUND

Note: The CONCLUSIONS section may include subject concepts not discussed in the article but that are setting up ideas for future study. NLM ignores these for the purposes of subject indexing.

Column 3: ENDING LABEL CONCEPT (Y/N)

Contains Y if the label is considered to be an "ending label" concept meaning that it includes data of a Results or Conclusions nature (not that the label occurs last in the order of sections).

Contains N if the label is not an "ending label" concept.

This distinction is important to the NLM definition of what constitutes a Structured Abstract.


Broadened Definition of Structured Abstracts to Enhance Readability (June 2013):

To enhance readability of structured abstracts in PubMed, NLM has
broadened the definition of a structured abstract so that it has at least one label that: To accommodate this broadened definition, NLM made a mid-year 2013 change to the NLMMedlineCitationSet DTD (used for MEDLINE/PubMed processing) which added a new NlmCategory attribute valid value, UNASSIGNED. The UNASSIGNED NlmCategory is used for labels in structured abstracts that NLM has not yet mapped to one of five categories, i.e., BACKGROUND, OBJECTIVE, METHODS, RESULTS, CONCLUSIONS. While the UNASSIGNED attribute values will appear in the PubMed data, versions of Updated Label List and NLM Category Mappings will continue to list only labels that have been mapped to the five other categories. NLM may in the future provide a list of labels with UNASSIGNED values for display purposes only.


Original NLM Definition of a Structured Abstract:

Not every abstract with apparent labels conveys the intent of a Structured Abstract. The original
NLM definition utilizes the following Rules to identify Structured Abstracts:

     Rule 1: Valid label - all uppercase string followed by a colon.

     Rule 2: Three or more valid labels must exist in abstract text.

     Rule 3: One label must come from the ending label list.

     Rule 4: None of the labels can be duplicates.

This definition was broadened in June 2013.


Reconstruction of Structured Abstracts for Display:

The 2011 DTD isolates a structured abstract label and stores it in an attribute.

<Abstract>
<AbstractText Label="BACKGROUND" NlmCategory="BACKGROUND">Elevated plasma concentrations of total homocysteine (tHcy) and obesity are risk factors for cardiovascular disease. The relationship between hyperhomocysteinemia and obesity has not been totally elucidated.</AbstractText>
<AbstractText Label="OBJECTIVE" NlmCategory="OBJECTIVE">The first aim of the study was to investigate whether anthropometric measurements and insulin resistance contribute to the variation in homocysteine levels in obese adults. Our second aim was to determine if any relationship exists between the carotid intima-media thickness (IMT) and plasma tHcy levels in obese subjects without traditional cardiovascular risk factors.</AbstractText>
<AbstractText Label="MATERIAL AND METHODS" NlmCategory="METHODS">Fifty-five obese (15 male, 40 female) and 30 (11 male, 19 female) age- and sex-matched apparently healthy volunteers were included. Exclusion criteria were smoking, hypertension, diabetes, vitamin ingestion, hyperlipidemia, renal failure, liver disease, pregnancy, menopause and secondary obesity such as Cushing's syndrome, hypothyroidism. tHcy, folate, vitamin B12 levels, fasting insulin, glucose, total cholesterol, triglycerides, HDL, LDL particles, uric acid, creatinine and creatinine clearance were measured. Non-invasive ultrasound measurements of carotid IMT were performed.</AbstractText>
<AbstractText Label="RESULTS" NlmCategory="RESULTS">tHcy levels and carotid IMT were comparable between obese and non-obese subjects. Waist/hip ratio (WHR) was related to tHcy and carotid IMT. Hyperhomocysteinemic subjects (tHcy >19.2 micromol/l) had greater WHR than normo-homocysteinemic subjects. Both tHcy levels and carotid IMT were higher in male subjects both in obese and non-obese subjects. No association was observed between insulin resistance and tHcy and carotid IMT. Renal function and abdominal obesity were significant predictors of plasma tHcy levels.</AbstractText>
<AbstractText Label="CONCLUSIONS" NlmCategory="CONCLUSIONS">We concluded that, in obese subjects who are free from atherosclerosis and impaired renal function, plasma tHcy levels do not differ from healthy subjects. Plasma tHcy concentrations are not related to carotid IMT in obese subjects during the non-atherogenic stage. Although no significant difference was observed between insulin-resistant and insulin-sensitive subjects compared to the plasma tHcy levels, the relationship between tHcy levels and some components of the insulin resistance syndrome may support the opinion that tHcy may be considered a component of the insulin resistance syndrome.</AbstractText>
</Abstract>
Example - PMID: 16419496 - 2011 XML showing Structured Abstract

The NLM guideline for reconstructing Structured Abstracts for display as a single paragraph is:

Reinsert the wording found in the Label= attribute followed by a colon space before the AbstractText data, except when that attribute value is UNLABELLED. In that case, ignore the attribute data and display only the AbstractText data on its own line at the margin. Insert one space before the next label.

BACKGROUND: Elevated plasma concentrations of total homocysteine (tHcy) and obesity are risk factors for cardiovascular disease. The relationship between hyperhomocysteinemia and obesity has not been totally elucidated. OBJECTIVE: The first aim of the study was to investigate whether anthropometric measurements and insulin resistance contribute to the variation in homocysteine levels in obese adults. Our second aim was to determine if any relationship exists between the carotid intima-media thickness (IMT) and plasma tHcy levels in obese subjects without traditional cardiovascular risk factors. MATERIAL AND METHODS: Fifty-five obese (15 male, 40 female) and 30 (11 male, 19 female) age- and sex-matched apparently healthy volunteers were included. Exclusion criteria were smoking, hypertension, diabetes, vitamin ingestion, hyperlipidemia, renal failure, liver disease, pregnancy, menopause and secondary obesity such as Cushing's syndrome, hypothyroidism. tHcy, folate, vitamin B12 levels, fasting insulin, glucose, total cholesterol, triglycerides, HDL, LDL particles, uric acid, creatinine and creatinine clearance were measured. Non-invasive ultrasound measurements of carotid IMT were performed. RESULTS: tHcy levels and carotid IMT were comparable between obese and non-obese subjects. Waist/hip ratio (WHR) was related to tHcy and carotid IMT. Hyperhomocysteinemic subjects (tHcy >19.2 micromol/l) had greater WHR than normo-homocysteinemic subjects. Both tHcy levels and carotid IMT were higher in male subjects both in obese and non-obese subjects. No association was observed between insulin resistance and tHcy and carotid IMT. Renal function and abdominal obesity were significant predictors of plasma tHcy levels. CONCLUSIONS: We concluded that, in obese subjects who are free from atherosclerosis and impaired renal function, plasma tHcy levels do not differ from healthy subjects. Plasma tHcy concentrations are not related to carotid IMT in obese subjects during the non-atherogenic stage. Although no significant difference was observed between insulin-resistant and insulin-sensitive subjects compared to the plasma tHcy levels, the relationship between tHcy levels and some components of the insulin resistance syndrome may support the opinion that tHcy may be considered a component of the insulin resistance syndrome.

Example - PMID: 16419496 - Structured Abstract Single Paragraph Display

The NLM guideline for reconstructing Structured Abstracts for an easier-to-read, multi-paragraph display is:

Reinsert the wording found in the Label= attribute followed by a colon space before the AbstractText data, except when that attribute value is UNLABELLED. In that case, ignore the attribute data and display only the AbstractText data on its own line at the margin. Typically, the label followed by the AbstractText displays on a new line with the label and the colon in bold with one or more blank lines between the sections/segments.

BACKGROUND: Elevated plasma concentrations of total homocysteine (tHcy) and obesity are risk factors for cardiovascular disease. The relationship between hyperhomocysteinemia and obesity has not been totally elucidated.

OBJECTIVE: The first aim of the study was to investigate whether anthropometric measurements and insulin resistance contribute to the variation in homocysteine levels in obese adults. Our second aim was to determine if any relationship exists between the carotid intima-media thickness (IMT) and plasma tHcy levels in obese subjects without traditional cardiovascular risk factors.

MATERIAL AND METHODS: Fifty-five obese (15 male, 40 female) and 30 (11 male, 19 female) age- and sex-matched apparently healthy volunteers were included. Exclusion criteria were smoking, hypertension, diabetes, vitamin ingestion, hyperlipidemia, renal failure, liver disease, pregnancy, menopause and secondary obesity such as Cushing's syndrome, hypothyroidism. tHcy, folate, vitamin B12 levels, fasting insulin, glucose, total cholesterol, triglycerides, HDL, LDL particles, uric acid, creatinine and creatinine clearance were measured. Non-invasive ultrasound measurements of carotid IMT were performed.

RESULTS: tHcy levels and carotid IMT were comparable between obese and non-obese subjects. Waist/hip ratio (WHR) was related to tHcy and carotid IMT. Hyperhomocysteinemic subjects (tHcy >19.2 micromol/l) had greater WHR than normo-homocysteinemic subjects. Both tHcy levels and carotid IMT were higher in male subjects both in obese and non-obese subjects. No association was observed between insulin resistance and tHcy and carotid IMT. Renal function and abdominal obesity were significant predictors of plasma tHcy levels.

CONCLUSIONS: We concluded that, in obese subjects who are free from atherosclerosis and impaired renal function, plasma tHcy levels do not differ from healthy subjects. Plasma tHcy concentrations are not related to carotid IMT in obese subjects during the non-atherogenic stage. Although no significant difference was observed between insulin-resistant and insulin-sensitive subjects compared to the plasma tHcy levels, the relationship between tHcy levels and some components of the insulin resistance syndrome may support the opinion that tHcy may be considered a component of the insulin resistance syndrome.

Example - PMID: 16419496 - Structured Abstract Multi-Paragraph Display

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