Library Philosophy and Practice 2012
Stem Cell Research: A Bibliometric Analysis from 1999-2008
Stem cell research is a vital area of study. It is of interest to scientists in India and all countries . Bibliometrics is a truly interdisciplinary research field. Bibliometrics comprises mathematics, social science, natural sciences, engineering, and life sciences. Bibliometric studies such as a work on the research productivity in ophthalmic and vision research used both the number of publications and qualitative measures of journals. This article is a bibliometric study of a part of the literature on stem cell research.
The terms bibliometrics and scientometrics were introduced by Pritchard and by Nalimov and Mulchenko in 1969. Pritchard explained the term bibliometrics as "the application of mathematical and statistical methods to books and other media of communication." There have been many bibliometric studies of the literature in the sciences in the last 40 years. In chemical information and computer sciences (CICS), a bibliometric approach was used to survey state-of-the-art of research. Journal of Chemical Information and Computer Sciences (JCICS) has been the leading journal in this area for the last 30 years.  One important element of bibliometrics is the author co-citation frequency matrix. It has been used to study Knowledge Management. Author co-citation frequencies were derived from the 1994-1998 academic literature and captured by the single search phrase of "Knowledge Management."  An economically and scientifically developing country like China has done research in the field of Neuroscience. A MEDLINE-based bibliometric analysis was done of the Chinese output in neuroscience for 1984 to 2001.  Research was done from the Inorganic Crystal Structure Database with the focus on growth rate, distribution of publications, productivity of authors, and multiple authorship patterns.  HIV/AIDS Research in India revealed the rapid growth of literature from 1992 onwards. The authorship distribution was examined using Lotka's Law. To identify the core journals Bradford's Law was used. The relative productivity of India was low and the focus was more on research and development.  Various aspects of nutrition research in Bangaladesh from 1972 to 2006 has been analyzed using bibliometrics. 
Materials and Methods
This study was confined to the published literature on the sub-discipline “Stem Cell” from the MEDLINE database. MEDLINE is the National Library of Medicine's (NLM) leading bibliographic database, which contains more than 18 million references to journal articles in the life sciences with a concentration on biomedicine. MEDLINE covers biomedicine, health, life sciences, biology, environmental science, marine biology, plant, and animal science. The period chosen for the study was 1999 to 2008. The total number of records was 54,373.
Need for the Study
A stem cell is a cell that has the ability to divide (self-replicate) for unlimited periods, often throughout the life of the organism. Under the right conditions, stem cells can differentiate to the many different cell types that make up the organism. Many different studies have explored the efficacy of stem cell treatment.    [12 
The study is confined to literature from 1999 to 2008 that is covered in MEDLINE.
The MEDLINE database was searched using the the Medical Subject Heading (MeSH) "Stem cell research". This yielded ten years of records that were downloaded into separate text files.
The data was investigated with Bibexcel. This was developed by Olle Persson of Umeå University in Sweden. This software is designed to analyse bibliographic data..
Objectives of the Study
The yearwise distribution of data according to the number of authors is presented in Table 1. The table shows that nearly 12.6% of the contributors were only by single authors and 12.86% is two authors research output. It clearly collaboration in stem cell research.
Table 1. Authorship pattern in Stem Cells
Diagram 1 depicts the authorship pattern in stem cell research from 1999 to 2008. Five or more authors are found on 41.24% of the records.
Diagram 1. Degree of Collaboration
The extent of the degree of collaboration was measured with the formula devised by K. Subramaniam.
The formula is
C = Degree of Collaboration in a discipline
Nm = Number of multiple authored papers
Ns = Number of single authored papers
Accordingly, the Degree of Collaboration has been calculated for the year 1999 is as follows:
C = -------------- = ------- = 0.89
2710 + 328 3038
The yearwise degree of collaboration falls between 0.82 and 0.9. The degree of collaboration for any subject ranges from 0.01 to 0.99 and it is always below 1 which has been proved by Karisiddappa, Maheswarappa and Shirol in Psychology and Bandyopadhyay in different disciplines such as Mathematics, Physics, Philosophy, Political Science and Mechanical Engineering.
Table 2. Degree of Collaboration in Stem Cell Research
Quantum of Stem Cell Research Activity
The research productivity in the source database and the quantum of records on stem cells covered is shown in the Table 3. Only 0.95% of the records in the MEDLINE database are on stem cells. The yearwise distribution of stem cell literature is shown in this table.
Table 3. Percentage of Literature Published from 1999 to 2008 in Stem Cell Research
Quantum of Stem Cell Research Productivity
The research productivity on 'Stem Cell' covered in the database is shown in Table 4.
Table 4. Quantum of Literature Published on Stem Cell from 1999 to 2008
The yearwise distribution of literature is shown in Table 4. The highest number of records (8,572) was published during 2008, followed by 7,870 in 2007, and 7,194 in 2006.
Distribution of Research Production by Language vs Year
The distribution of literature by language is presented in Table 5.
Table 5. Stem Cell Research Productivity by Language
Distribution of Stem Cell Research Productivity - Country Vs Year
Stem cell research by country and yearwise is presented in the Table 6. The USA has ranks first followed by the United Kingdom 11,397, and the Netherlands with 2,942 records. India is in 16th place with 203 records.
Table 6. Year vs. Country wise Distribution of Stem Cell Research
Relative Growth Rate and Doubling Time for Stem Cell Research Output
The Relative Growth Rate (RGR) is the increase in number of articles/pages per unit of time. The mean Relative Growth Rate (R) over the specific period of interval can be calculated from the following equation:
Loge 2W – loge 1W
2T - 1 T
1-2`R = mean relative growth rate over the specific period of interval
loge 1W = log of initial number of articles/pages
loge 2W = log of final number of articles/pages after a specific period of interval
2T - 1T = the unit difference between the initial time and the final time
The year can be taken here as the unit of time. The RGR for both articles and pages can be calculated separately.
1 - 2R (aa -1 year -1) can represent the mean relative growth rate per unit of articles per unit of year over a specific period of interval.
1 - 2 R ( pp -1 year -1) can represent the mean relative growth rate per unit of pages per unit of year over a specific period of interval.
It is seen from rable that there is decrease in RGR by year.
Table 7. RGR and Dt for Stem Cell Research Output by Year-wise
The RGR has decreased from 2000 (0.74) to 2008 (0.17) in the span of 10 years (Figure 1).The Doubling Time (Dt) has increased when calculated yearwise.The Doubling Time increases from 0.93 in 1999 to 4.03 in 2008 (Figure 2).
Doubling Time (Dt)
There exists a direct equivalence between the relative growth rate and the doubling time . If the number of articles/pages of a subject doubles during a given period then the difference between the logarithms of numbers at the beginning and end of this period must be logarithms of number 2. If natural logarithm is used this difference has a value of 0.693. Thus the corresponding doubling time for each specific period of interval and for both articles and pages can be calculated by the formula:
Doubling time (Dt) =
Doubling time for articles Dt (a) =
1 -2 `R ( aa-1 year-1 )
Doubling time for pages Dt (p) =
1 -2 `R ( pp-1 year-1 )
Figure 2. Publication Types Vs. yearwise Distribution of Stem Cells Research
The Table 8 reveals that the distribution of the stem cell research output according to publication type and year of publication.
It is an accepted fact that most of the scholarly communication of scientific research is published in journals and sometimes presented in the conferences. Of course, those conference papers are further updated and published in journals of the respective field of knowledge. Therefore, scientific communication is being mostly made through periodicals, the primary vehicles of research communication.
In this study, about 75.27% have published in journals, 7.45% have published in comparative studies, and 2.47% are published in comments.
Table 8. Publication Type of Stem Cells Vs Year
Figure 3 represents the different types of publications in the research output in Stem Cells.
Ranking of Journals in Stem Cell Research
Ranking of the journals on the research output on 'Stem Cell "during the study period has been presented in the below Table 9. With the 1908 contributions "Blood" Journal took in the First Rank, the "Stem-Cells" with 971 contributions and "Proc-Natl-Acad-Sci-U-S-A." 890 contributions stand Second and Third Rank. The researcher finds out of 15 ranking journals for the specific publication. Bone Marrow Transplantation goes to sixth place.
Table 9. Ranking of Journals in Stem Cell Research
Distribution of Journals in Stem Cells based on Bradford Law of Scattering
Bradford first formulated his law, but it did not receive wide attention until the first publication of his book 'Documentation' in 1948. Bradford examined all of the journal titles contributing to a bibliography on applied Geophysics. He divided the list into three 'zones' each containing roughly equal number of references. On the basis of this observation Bradford deduced his law.
"If scientific periodicals are arranged in the order of decreasing productivity of articles on a given subject, they may be divided into a nucleus of periodicals more particularly devoted to the subject and several groups or zones containing the same number of articles as the nucleus where the number of periodicals in the nucleus and the succeeding zones will be as 1: n:n2"
Table 10. Distribution by Zone of Cited Journals and References in Stem Cells
It is seen from the table 10 shows that 156 core journals are grouped in zone-1 published 18156 articles accounts for one third of the total output. Similarly the second zone comprises of 1288 journals and 9269 journals grouped in third zone. The Bradford's Law states that the number of periodicals in zones, the first zone and second zones will be 1: n: n2...... According to the relationship is the zone will be 156: 1288: 9269. On comparison with the data in Table, it is clear that the trend of research publication confirms the implication of Bradford's Law
1. A total of 54,373 publications were covered in MEDLINE database for the period 1999-2008.
2. USA ranks as the top most country with maximum number of contributions followed by United Kingdom England and Netherland as second and third positions respectively..
3. It was found that about 88.52% of total output was published in English language, followed by Chinese 2.86% and Japanese 0.94%
4. "Journal articles" contributed 75.27% followed by "Comparative Study" 7.45% of the total output.
5. There was a decrease in Relative Growth Rate and an increase in the Doubling Time for research productivity from year after year throughout the study period.
6. The degree of collaboration has been arrived at 0.9 during the study period
7. It was found that a maximum number of contributions (1908) were published in the journal 'Blood.. This is followed by 'Stem Cell' with 971 contributions
8. The research productivity of Stem Cell confirms the implications of Bradford's Law of Scattering
9. There exists a significant level of difference between Stem Cell research performance of Indian scientists and scientists of other countries.
10. Among the developing countries, India contributes substantially in Stem Cell Research.
Research in stem cells will help us understand how they transform into the dazzling array of specialized cells that make us what we are. A better understanding of normal cell development will allow us to understand and perhaps correct the errors that cause of medical deffects. Another imprtant application of stem cells is making cells and tissues for medical therapies. Today, donated organs and tissues are often used to replace the diseased or destroyedn organs. Unfortunately, a large number of people needing a transplant far exceeds the number of organs available for transplantation. Stem cells offer the possibility of a renewable source of replacement cells and tissues to treat a myriad of diseases, conditions, and disabilities including Parkinson's disease, amyotrophic lateral sclerosis, spinal cord injury, burns, heart disease, diabetes, and arthritis. Research with the use of stem cells in the treatment of diseases like heart, liver, brain and spinal cord had remained in the experimental stage like India. Limited contolled clinical trials in human had been permitted. The results were closely monitored by experts.  India started to set up a "stem cell priority fund" to maintain research via stem cells and find healing for diabetes, heart and nerve diseases. ''We have submitted a proposal of an exclusive fund for stem cell research. I think the government is keen to set up the stem cell priority fund,'' announced D Balasubramanian, Chairman of the task force on stem ccell research of the Department of Biotechnology (DBT), at the Indo-UK stem cell workshop organised jointly by India and Britain.
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