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NLM Milestones: The Hits Just Keep on Coming

February 17, 2011

This year marks the 175th anniversary of the National Library of Medicine (NLM). While that's a major milestone, there was a lot to celebrate in 2010 as well. So we decided to take a look back at a banner year.

The Medical Subject Headings (MeSH®) vocabulary marked its 50th anniversary. PubMed Central® and ClinicalTrials.gov each turned 10. And, in an interesting bit of synchronicity, PubMed Central added its 2 millionth article and PubMed® its 20 millionth citation on the same day, July 27, 2010.

ClinicalTrials.gov
On February 29, 2000, the National Institutes of Health (NIH) announced the launch of ClinicalTrials.gov, a free public registry of clinical trials funded by the NIH, other federal agencies and private industry. When the database was launched, it contained information on more than 4,000 studies taking place at 47,000 locations in the United States.

In the past decade, those numbers have grown dramatically. At the end of 2010, the database contained information on more than 100,000 studies in all 50 states in the US plus 173 other countries. ClinicalTrials.gov receives 65,000 visitors a day and more than 50 million page views per month. It is the largest single registry of clinical trials and a resource for patients, healthcare providers, researchers and members of the public. The database provides easy access to information about a trial's purpose, who may participate, locations, and phone numbers for more details.

The National Library of Medicine developed and administers ClinicalTrials.gov. Dr. Deborah Zarin of the Lister Hill National Center for Biomedical Communications leads the project. She notes that over the past 10 years, there's been a cultural shift in registering trials. "Organizations around the world sponsoring trials now know they need to register them," she says. "It's really newsworthy to find a trial that hasn't been registered."

In September 2008, ClinicalTrials.gov started to allow submission of summary results. The addition of the results database came about because of 2007 legislation requiring expanded registration and results reporting for certain clinical trials of drugs, biologics and devices. The results database includes information about the numbers and types of participants, a summary of the pre-specified outcomes, and a listing of adverse events that occurred during the trial, as well as links to published articles about the trial. There is no information that can identify a patient.

More than 2,600 results have been posted so far, and are integrated into the clinical trials record. Dr. Zarin points out that not all clinical trials end up getting published, so the results database will be a unique source for information about those trials.

ClinicalTrials.gov grew out of 1997 legislation that required the Department of Health and Human Services, through the NIH, to broaden the public's access to information about clinical trials by establishing a registry for both federally and privately funded trials "on drugs for serious or life-threatening diseases and conditions."


PubMed Central
2010 was a notable year for PubMed Central (PMC). The archive marked its 10th anniversary and added its 2 millionth full-text article.

PubMed Central is the National Institutes of Health free digital archive of life sciences and biomedical journal literature. The database was developed and is maintained by the National Center for Biotechnology Information (NCBI) at the National Library of Medicine (NLM).

When PubMed Central debuted in 2000, it contained just two journals, Proceedings of the National Academies of Sciences of the United States of America and Molecular Biology of the Cell.  PMC grew steadily and experienced a growth spurt in 2008 when the NIH Public Access Policy became mandatory.

Today, PubMed Central includes more than 750 full deposit journals as well as NIH-funded articles and manuscripts, and issues of historic journals dating back to the 1800s. On an average day, 420,000 people use the site and access 740,000 articles.

In addition to its growth, another sign of PubMed Central's success is that it's been replicated. There currently are two PMC International (PMCI) centers, UKPMC in the United Kingdom and PMC Canada launched in 2010.

"PubMed Central has developed into an extremely valuable resource for those of us who are out in the trenches trying to do research and teach," says Gary Ward, PhD, a professor of microbiology and molecular genetics at the University of Vermont and chair of the PubMed Central National Advisory Committee. Ward spoke at the PubMed Central 10th anniversary celebration held at the National Library of Medicine in June. The celebration, timed to coincide with the PMC advisory committee's meeting, reunited PubMed Central pioneers for a lively panel discussion.

Dr. Harold Varmus, the former NIH Director who was instrumental in the creation of PMC during his tenure, appeared by video and called the advent of PMC "truly revolutionary." Also appearing by video was Sir Mark Walport, director of the Wellcome Trust, a global charity foundation dedicated to improving health, and a major sponsor and funder of UKPMC.  "A piece of research isn't finished until it's published," he said. "We want to make sure the results of the research we fund are available to as many people as possible."

Panelist Elizabeth Marincola expanded on that thought, suggesting "research isn't complete until it's accessible." Marincola was the executive director of the American Society for Cell Biology when PubMed Central launched. The society's journal, Molecular Biology of the Cell, was the first in PubMed Central. Other panelists included: Heather Joseph, who was managing editor of Molecular Biology of the Cell during the debut of  PMC; Paul Ginsparg,  PhD, a physics professor at Cornell University who was on the PMC advisory committee in the early days; and moderator Sir Richard J. Roberts, Nobel Laureate, research director of New England Biolabs.

NLM Director Dr. Donald A.B. Lindberg, appeared by video and acknowledged PubMed Central's "great accomplishment." He said he's proud of the team at NCBI and Library Operations. NCBI Director Dr. David Lipman thanked the PMC advisory committee and the people who make PMC happen, calling them "an incredibly gifted, dedicated and talented group of people."

MeSH
Every day, millions of people access NLM's popular MedlinePlus® and PubMed Web sites searching for medical information.  The framework that underlies both systems, NLM's  Medical System Headings (MeSH), marked its 50th anniversary in November with a special lecture by Robert Braude, PhD, a pioneer in the field. Dr. Stuart Nelson, who heads the MeSH section, invited Dr. Braude to talk about MeSH as a way to commemorate this unique NLM innovation as a prequel to the Library's 175th anniversary.

MeSH, the first medical vocabulary created especially for use with a computer search system, remains one of the NLM's greatest innovative ventures. Its roots stretch back to 1948, when some of the first pioneers in the field of medical library information and retrieval services began looking for ways to use computer technology for logical, organized searches.

After more than a decade of development, the inaugural MeSH edition appeared in 1960, showcasing a truly new approach to library information management. It entailed a set of medical subject headings for both cataloging subject descriptions of books and for indexing journal articles. Until then these had been separate library functions. MeSH also presented the first vocabulary for automated systems.

Today, MeSH features a controlled-vocabulary thesaurus that indexes articles from 5,400 of the world's leading biomedical journals for the MEDLINE/PubMed database. It also has a database of the books, documents and audiovisuals acquired by the Library. 

"MeSH is the skeleton, the underlying structure of the Library's medical information," says Jacque-Lynne Schulman, Senior Technical Information Specialist with MeSH. "It provides user-friendly access to a constantly changing medical vocabulary. It is essential for searching in an ocean of information."

MeSH structures the information under headings, called descriptors, alphabetically and hierarchically. These go from the broadly general anatomy, for example, to the narrowly specific, such as the hand, thereby permitting searches of varying depth.

The 2010 version of MeSH contains 25,588 descriptors and more than 172,000 entry terms to assist finding the most appropriate MeSH Heading. Also, there is a separate thesaurus containing more than 190,000 headings for Supplementary Concept Records (formerly Supplementary Chemical Records).

In his laudatory commemorative remarks at the Lister Hill auditorium on November 18, where NLM Deputy Director Betsy L. Humphreys introduced him to a large, enthusiastic audience, Dr. Braude recalled that his long association with the Library stretched back to 1965, when he had come to the Library for MEDLARS training. "The MeSH tree has borne new fruit and will continue to influence the field of medical bibliography," he said.

Dr. Braude’s MeSH commemorative lecture was co-sponsored by the History of Medicine Division and the Medical Subject Headings Section. The lecture was recorded and archived and can be viewed at NIH videocasting and podcasting.

Information compiled by NLM in Focus writers Thomas Conuel and Christopher Klose, and editor Shana Potash