Say we are interested in what research has been done on the effect of estrogen on the neuropeptide neurotensin. Simply searching on estrogen brings up over 100,000 hits (far too many to be useful). However, if we narrow our search using the Boolean operator AND we can narrow this considerably.

Estrogen AND neurotensin : 37 hits

The AND is one of three Boolean operators (AND, OR, NOT) recognized by PubMed and OVID. These must be typed in all caps and can be grouped by use of parenthesis. e.g. say we want to see the effect of stress or dehydration on migraine headache. You could phrase this as:(stress OR dehydration) AND migraine. How you group the parenthesis is important.

Instructions for constructing focused searches are provided as tutorials or FAQ sheets in PubMed. The same strategies can generally be applied to an Ovid search.

1. Use of the Clipboard

As you scroll through the pages of hits, check the box adjacent to the ref number for articles that look of interest. BEFORE you move to page two of the reference list click use the Send to pull down menu at either the top or bottom of the list and select Clipboard.This will capture the checked references on a clipboard. Next move to page two and repeat the process. Using the Send to clipboard pull down menu will add the checked references from the second page to the clipboard. (note: Items on the clipboard are only retained for eight hours)

You can now check the clipboard (faint blue heading in topmost grey band) to view the items on the clipboard

The default display shows author, article title and journal. For more information, change the Display pull-down menu from Summary to Abstract and click on the Display button. This will now display a full abstract.

Clicking on the Limits term at the top of the page allows you to restrict your search in a number of ways.

a) Publication types- Allows you to restrict hits to specific types of articles or specific languages. Choosing Review Articles is very useful if you want to get an overview of what has been done on a specific topic. Try a new search

e.g. VIP AND inflammation brings up over 180 articles

Click on the Limits tab and use the Publication Type pull down menu to select only Reviews and then click on Go button again. Now only 40 articles appear

b) Subject limits: You can also limit on ages of experimental human subjects (.e. pediatric vs gerontological). You can limit articles to humans or to animal studies or both, you can limit by gender, by age of subjects, by date of publication or specify article language.

(note: if you do employ limits on one search, make sure you uncheck this box before proceeding with another search or the limits will still be applied to the subsequent searches.

3. Use of Truncation

It is possible to employ the * to search for all terms that begin with a defined text string. For example,  searching on myo* will search for all articles dealing with myoblast, myocyte, myocystitis, myopathy, etc up to 150 variations. Searching on myocyte* will search for myocyte or myocytes or myocytemia but not  myocytoma.

4. Use of Related Articles

To the right of the journal entry, you can survey "related articles" (those that MEDLINE analyzes as related by virtue of shared keyword entries),. These will be brought up not in publication date order, but in order of degree of relatedness. This can be a very useful tool to finding related publications that do not include your search terms in either title or abstract.

If you click on Links and scroll down to Books, you will bring up the title and abstract with a number of terms highlighted as links. These terms are linked to the collection of books whose full text is available on line via PubMed. This can be extremely useful for getting some fundamental background information on a subject. The number of full text books on line is increasing with each year.

6. Full Text On-Line

Most of the journals which give an icon indicating full text on-line actually require a Password to see the full text.However, some journals (e.g. Proc. Natl. Acad. Sci. USA) are actually available as full text in the form of a html or pdf document. One of the advantages of using OVID via the Tufts library is that a much wider selection of journals is available as full text on-line via Tufts and the OVID search engine indicates which journals are available.

Entrez is powerful because it is actually a set of linked databases. With a given search term you can also search the DNA sequence databases, the protein structure databases, the online Mendelian Inheritance in Man (OMIM) database, and a number of others from one central page. If you are searching for a gene you can cross reference in OMIM to see if it is associated with any known human genetic disease (ONE CAVEAT:  BE VERY JUDICIOUS IN PRINTING  THESE - OMIM ENTRIES ARE ENCYCLOPEDIC AND CAN GIVE MORE THAN 50 PAGES OF HIGHLY TECHNICAL TEXT. Better to cut and paste relevant material to a word processor).