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Biomedical subjects

E D Johnson

Publications and source records attributed to E D Johnson.

At least 19 recordsLinked to original sources

Astrophysical reaction rate for the neutron-generator reaction 13C(alpha,n)16O in asymptotic giant branch stars.

The reaction 13C(alpha,n) is considered to be the main source of neutrons for the s process in asymptotic giant branch stars. At low energies, the cross section is dominated by the 1/2+ 6.356 MeV subthreshold resonance in (17)O whose contribution at stellar temperatures is uncertain by a factor of 10. In this work, we performed the most precise determination of the low-energy astrophysical S factor using the indirect asymptotic normalization (ANC) technique. The alpha-particle ANC for the subthreshold state has been measured using the sub-Coulomb alpha-transfer reaction ((6)Li,d). Using the determined ANC, we calculated S(0), which turns out to be an order of magnitude smaller than in the nuclear astrophysics compilation of reaction rates.

Journal Article↗

First ultraviolet high-gain harmonic-generation free-electron laser.

We report the first experimental results on a high-gain harmonic-generation (HGHG) free-electron laser (FEL) operating in the ultraviolet. An 800 nm seed from a Ti:sapphire laser has been used to produce saturated amplified radiation at the 266 nm third harmonic. The results confirm the predictions for HGHG FEL operation: stable central wavelength, narrow bandwidth, and small pulse-energy fluctuation.

Journal Article↗

Differences among families coping with serious mental illness: a qualitative analysis.

Families of 180 people with serious mental illness, representing various socioeconomic and ethnic groups, were interviewed about their understanding of their family member's illness, coping with problems caused by the illness, sources of support, effects of medication and substance abuse, and dealing with mental health professionals. Several significant areas of concern emerged, and are explored with attention to differences based on gender, ethnic group, socioeconomic status, and role of the family member.

Adaptation, Psychological↗

Criteria for evaluating alternative MEDLINE search engines.

With so many options available for searching MEDLINE on the World Wide Web or as a component of an online service, evaluation criteria are suggested as a means of assisting librarians in determining the positive and negative aspects of alternative MEDLINE sites. A set of searches was utilized to systematically compare MEDLINE sites. Sites evaluated included Avicenna, America Online, HealthGate, PubMed, Medscape, and Physicians' Online. Some features used to evaluate these sites were: default fields; operators (default); access to MeSH; subheadings; stop words protected in MeSH; truncation; and stemming. This article will describe the group process used to arrive at the evaluation criteria, as well as some general conclusions which will help librarians in directing their users to a particular MEDLINE site.

Abstracting and Indexing↗

An analysis of objective quality indicators on Year Book citations: implications for MEDLINE searchers.

PURPOSE: This study is an analysis of Mosby Year Book citations from Ovid Online's Comprehensive Core Medical Library (CCML). The purpose of this study was twofold: (1) to determine whether Year Book citations were more likely to be judged "key" than non-Year Book citations by clinicians; and (2) to determine whether the MEDLINE record of Year Book citations evaluated as key contained objective quality indicators that searchers might use to target key articles. BACKGROUND: As part of the MEDLINE/Full-Text Research Project, health care professionals evaluated search output from CCML on a five-point scale. The scale included the choice "key" for those items which the evaluator would not want to miss. Because the output contained items from the Year Book series, it was possible to determine whether the Year Book items were evaluated as key more frequently than expected. METHODS: This study analyzes the MEDLINE records corresponding to 110 references from the Mosby Year Book series evaluated as key by clinicians receiving search output from CCML. The records were examined for the presence of such searchable elements as Medical Subject Headings (MeSH) terms and publication types related to study design, evidence of research support, inclusion in the Abridged Index Medicus (AIM) subset, and a comments field. Also noted were the presence of a structured abstract, study design details in the author abstract, and inclusion in more than one Year Book. RESULTS: A chi-square test (p < .001 indicated that the proportion (33%) of Year Book citations marked key on the searches was significantly higher than that of non-Year Book citations (18%). When the occurrence of the searchable elements was compared to MEDLINE as a whole, the following access points appeared more frequently in the key Year Book records: study design terms categorized under epidemiologic methods in the MeSH Tree Structures; the checktag comparative study; AIM subset; comments field; and, publication types (pt) clinical trial, randomized controlled trial, multicenter study, and meta-analysis. CONCLUSIONS: These searchable elements should be helpful in targeting some, but not all, key articles in MEDLINE.

Chi-Square Distribution↗

Characterization of a new Marburg virus isolated from a 1987 fatal case in Kenya.

In 1987, an isolated case of fatal Marburg disease was recognized during routine clinical haemorrhagic fever virus surveillance conducted in Kenya. This report describes the isolation and partial characterization of the new Marburg virus (strain Ravn) isolated from this case. The Ravn isolate was indistinguishable from reference Marburg virus strains by cross-neutralization testing. Virus particles and aggregates of Marburg nucleocapsid matrix in Ravn-infected vero cells, were visualized by immunoelectron microscopic techniques, and also in tissues obtained from the patient and from inoculated monkeys. The cell culture isolate produced a haemorrhagic disease typical of Marburg virus infection when inoculated into rhesus monkeys. Disease was characterized by the sudden appearance of fever and anorexia within 4 to 7 days, and death by day 11. Comparison of nucleotide sequences for portions of the glycoprotein genes of Marburg-Ravn were compared with Marburg reference strains Musoki (MUS) and Popp (POP). Nucleotide identity in this alignment between RAV and MUS is 72.3%, RAV and POP is 71%, and MUS and POP is 91.7%. Amino acid identity between RAV and MUS is 72%, RAV and POP is 67%, and MUS and POP is 93%. These data suggest that Ravn is another subtype of Marburg virus, analogous to the emerging picture of a spectrum of Ebola geographic isolates and subtypes.

Adolescent↗

Chemiluminescent detection of RFLP patterns in forensic DNA analysis.

DNA testing by restriction fragment length polymorphism (RFLP) analysis is an extremely important technique used in forensic science laboratories. While RFLP testing is a highly informative method, it traditionally has had several disadvantages. It is time consuming and involves work with radioactive phosphorous. A detection method that is faster and safer than isotopic detection is presented. Various membranes, fixation methods and transfer procedures were evaluated for DNA retention and sensitivity using alkaline phosphatase conjugated oligonucleotide probes and a chemiluminescent substrate. Blood samples and evidentiary material from forensic casework were analyzed by both chemiluminescent and isotopic detection. Results of each method were compared for pattern appearance, band size, and composite profile frequency. The chemiluminescent system had very good sensitivity, detecting 3-25 ng K562 DNA. Most patterns developed by both methods appeared the same. The variation observed between band sizes and frequency estimates generated by each method was as expected for an inter-gel comparison. The chemiluminescent detection procedure described here is suitable for use in forensic casework.

Alleles↗

Beyond relevance--characteristics of key papers for clinicians: an exploratory study in an academic setting.

OBJECTIVE: The purpose of this study was to determine what factors beyond relevance influence a clinician's decision to choose to read one journal article over another in satisfying an information need. DESIGN: Seventeen health care providers were interviewed and then surveyed regarding the characteristics of key articles (those they would not want to miss). On a Likert scale, the clinicians graded forty-two characteristics for importance in the decision process. Relevance was assumed and not at issue. SETTING: The study took place in an academic health science center. SUBJECTS: The subjects were seventeen clinicians, all with patient care responsibilities. There were four internists, four surgeons, three family practitioners, three pediatricians, two psychiatrists, and one clinical psychologist. RESULTS: Factors beyond relevance that most often influenced the decision process pertained to methodological rigor, authors and their institutional affiliations, document types, and population studied. CONCLUSIONS: Among the clinicians surveyed, factors beyond topicality influenced judgments as to what constitutes an important article. The emphasis respondents gave to certain attributes is echoed in other published work and highlights the need for more intensive investigation of these non-subject indicators as search parameters. Improved searching capabilities might well lead to a significant reduction in the clinician's information overload.

Attitude of Health Personnel↗

Retrieving research studies: a comparison of bibliographic and full-text versions of the New England Journal of Medicine.

It has been established that subject searches of medical full-text databases obtain higher recall than subject searches in a bibliographic database. In this study we attempted to determine if the same rule might apply when searching for a non-subject parameter such as study design. A simultaneous search of bibliographic and full-text records from the New England Journal of Medicine provided data on the number of items retrieved by each kind of search. Filtering strategies were created for 5 different study types: randomized controlled trials, other clinical trials and prospective studies, cohort studies, longitudinal and follow-up studies, and multicenter studies. The point of the study was to compare the numbers of items retrieved from the bibliographic database, MEDLINE, and those retrieved from the full-text version of NEJM, and to examine the unique access points available in each file. For all the study types the full-text file retrieved a larger number of records than MEDLINE, most of which were retrieved because of methodology terms found in the text but not in the title or abstract. In MEDLINE, descriptors and publication types, two value-added fields supplied by indexers, retrieved 11-89% more than title and abstract alone.

Abstracting and Indexing↗

Detection of prostate specific antigen by ELISA.

A method for the detection of prostate specific antigen (PSA or P30) by enzyme linked immunosorbent assay (ELISA) has been developed. The method was evaluated for sensitivity and specificity and compared to other methods of semen identification on numerous casework samples. A sensitivity of less than 1 ng/mL PSA is routinely achieved. Numerous domestic contaminants and body fluids were tested and none were found to give a false-positive result. However, false-negative results did occur in samples contaminated with detergents. Additionally, some poorly preserved items of evidence did not give positive results where expected. In spite of these minor limitations, this method was found to be highly sensitive and specific and an efficient method for identifying semen in forensic casework.

Acid Phosphatase↗

Students online: learning medical genetics.

It is possible to focus medical genetics education by using a model that integrates the skills of end-user searching of the medical literature into the traditional course content. Since 1988, 313 first-year medical students were studied as they accessed MEDLINE to retrieve information about biochemical genetic disorders. Their search behavior was studied by analyzing data from the National Library of Medicine's traffic files. The skills that they initially learned were reinforced as they searched clinical genetics problem cases in the second-year pathology course, and these skills were consolidated in the third year when the students addressed specific patient-care questions in pediatrics. The students' perception of the value of this model was studied by analyzing questionnaires completed during the exercise. It was demonstrated that when students were taught the skills of accessing MEDLINE by computer, they could formulate a question, retrieve current information, critically review relevant articles, communicate effectively, and use these skills to contribute to patient care.

Female↗

Medical students using Grateful Med: analysis of failed searches and a six-month follow-up study.

Medical students at the University of Missouri were taught to search MEDLINE using the Grateful Med software. The traffic files of student searches were analyzed for search behavior. This paper reports on two specific aspects of these analyses: (1) failed searches where retrieval was either too large or too small (zero hits); and (2) a six month follow-up study which focused on error rates and retention of skills. The two major reasons for retrieving too many citations were entering a phrase on a single subject line and a search of only one concept. Of the zero hit searches, the most commonly occurring errors were MeSH (medical subject headings) not used, other MeSH errors, misspelling or keyboard errors, and faulty logic. During the six month follow-up study, the error rates of students declined in spite of the fact that they had not used the software in six months. Furthermore, a larger percentage of the searches showed a more sophisticated use of MeSH than previously employed.

Education, Medical↗

The application of quality filters in searching the clinical literature: some possible heuristics.

Experienced searchers can help their patrons find the "best" by employing any of several techniques which might filter search results. Using a sample search on Alzheimer's Disease, this article describes and illustrates the following five objective indicators which might be considered signs of quality: methodological rigor, document attributes, peer review, journal reputation, and filtering at input. Sample techniques and results are presented for six databases: MEDLINE, CINAHL, EMBASE, SAMM, CCML, and JWAT. Understanding of the patron's need and knowledge of the structure and contents of the database will determine when each should be applied to search results.

Alzheimer Disease↗

Filovirus contamination of cell cultures.

The filoviruses Marburg and Ebola comprise a newly recognized family of viruses. The first filovirus to be isolated was Marburg virus in 1967. This virus was imported in shipments of African green monkeys from Uganda and infected several cell-culture technicians, with serious illness resulting. The rarity of Marburg and Ebola virus transmission, decreasing use of imported African monkeys, and quarantine efforts have presumably been responsible for the lack of additional episodes until 1989, when a new filovirus related to Ebola was isolated from quarantined monkeys in Reston, Virginia. This virus was imported on multiple occasions from a Philippine supplier of cynomolgus macaques as a consequence of an epidemic of acute infections in the foreign holding facility. While quarantine procedures prevented the use of any of these animals in research and the three human infections that occurred were asymptomatic, this episode emphasizes that these little understood viruses have considerable potential for mischief. The finding of antibodies reacting with Ebola viruses in many biomedically important Old World primates, including colonized monkeys in the U.S., emphasizes the need for more research to understand the specificity of the antibodies, spectrum of filovirus strains in nature, potential hosts, and true distribution of the family. The filoviruses grow well in primary and established cell strains and cell lines, and cytopathogenic effects may be absent or require several days to be manifest, leading to the possibility of occult contamination. The known viruses are readily detected by polyclonal and monoclonal antibody staining of cells and by electron microscopy; nucleic acid probes exist to develop more sensitive techniques if warranted.

Animals↗

The Medline/full-text research project.

This project was designed to test the relative efficacy of index terms and full-text for the retrieval of documents in those MEDLINE journals for which full-text searching was also available. The full-text files used were MEDIS from Mead Data Central and CCML from BRS Information Technologies. One hundred clinical medical topics were searched in these two files as well as the MEDLINE file to accumulate the necessary data. It was found that full-text identified significantly more relevant articles than did the indexed file, MEDLINE. The full-text searches, however, lacked the precision of searches done in the indexed file. Most relevant items missed in the full-text files, but identified in MEDLINE, were missed because the searcher failed to account for some aspect of natural language, used a logical or positional operator that was too restrictive, or included a concept which was implied, but not expressed in the natural language. Very few of the unique relevant full-text citations would have been retrieved by title or abstract alone. Finally, as of July, 1990 the more current issue of a journal was just as likely to appear in MEDLINE as in one of the full-text files.

Abstracting and Indexing↗

Retrieval from full-text medical literature: the dream & the reality.

While the retrieval of the full-text of a document might seem to end all the hassle of using traditional retrieval systems, the results of the MEDLINE/Full-Text Project indicate that retrieval from the current full-text databases of biomedical journal literature does not match the dream. During the first phase of the project the researchers learned that searching the full-text databases resulted in the retrieval of a significantly larger number of relevant documents than MEDLINE. However, the full-text databases also resulted in a large number of non-relevant documents. Currently the researchers are focusing on how to search these databases to continue retrieving the large number of relevant documents but without so many non-relevant items.

Databases, Bibliographic↗

Preliminary report: isolation of Ebola virus from monkeys imported to USA.

An epizootic caused by an Ebola-related filovirus and by simian haemorrhagic fever virus began among cynomolgus monkeys in a US quarantine facility after introduction of monkeys from the Philippines. This incident, the first in which a filovirus has been isolated from non-human primates without deliberate infection, raises the possibility that cynomolgus monkeys could be a reservoir of Ebola virus infection.

Animals↗