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Long EC, Smith RL, Scott JT, Gay B, Giray C, Storace R, Guillot-Wright S, Crowley DM. A new measure to understand the role of science in US Congress: lessons learned from the Legislative Use of Research Survey (LURS). Evid Policy 2021; 17:689-707. [PMID: 35586821 PMCID: PMC9109878 DOI: 10.1332/174426421x16134931606126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
BACKGROUND There is growing interest in and recognition of the need to use scientific evidence to inform policymaking. However, many of the existing studies on the use of research evidence (URE) have been largely qualitative, and the majority of existing quantitative measures are underdeveloped or were tested in regional or context-dependent settings. We are unaware of any quantitative measures of URE with national policymakers in the US. AIMS AND OBJECTIVES Explore how to measure URE quantitatively by validating a measure of congressional staff's attitudes and behaviors regarding URE, the Legislative Use of Research Survey (LURS), and by discussing the lessons learned through administering the survey. METHODS A 68-item survey was administered to 80 congressional staff to measure their reported research use, value of research, interactions with researchers, general information sources, and research information sources. Confirmatory factor analyses were conducted on each of these five scales. We then trimmed the number of items, based on a combination of poor factor loadings and theoretical rationale, and ran the analyses on the trimmed subscales. FINDINGS We substantially improved our model fits for each scale over the original models and all items had acceptable factor loadings with our trimmed 35-item survey. We also describe the unique set of challenges and lessons learned from surveying congressional staff. DISCUSSION AND CONCLUSIONS This work contributes to the transdisciplinary field of URE by offering a tool for studying the mechanisms that can bridge research and policy and shedding light into best practices for measuring URE with national policymakers in the US.
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Affiliation(s)
- E C Long
- Pennsylvania State University, USA
| | - R L Smith
- Virginia Commonwealth University, USA1
| | | | - B Gay
- University of Maryland, USA
| | - C Giray
- Pennsylvania State University, USA
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Long EC, Ohlsson H, Sundquist J, Sundquist K, Kendler KS. Different Characteristics and Heritabilities of Alcohol Use Disorder Classes: A Population-Based Swedish Study. Alcohol Alcohol 2019; 54:647-655. [PMID: 31556919 DOI: 10.1093/alcalc/agz069] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 06/23/2019] [Accepted: 07/14/2019] [Indexed: 11/13/2022] Open
Abstract
AIMS The aims of the present study are to identify alcohol use disorder (AUD) classes among a population-based Swedish sample, determine if these classes differ by variables known to be associated with AUD and determine whether some AUD classes have stronger genetic influences than others. METHODS A latent class analysis (LCA), based on types of registrations, was conducted on Swedish individuals with an AUD registration born between 1960 and 1990 (N = 184,770). These classes were then validated using demographics; patterns of comorbidity with drug abuse, psychiatric disorders and criminal behavior; and neighborhood-level factors, i.e. peer AUD and neighborhood deprivation. The degree of genetic and environmental influence was also investigated. RESULTS The best-fit LCA had four classes: (a) outpatient/prescription, characterized by a mix of outpatient medical and prescription registrations, (b) low-frequency inpatient, characterized entirely by inpatient medical registrations, with the majority of individuals having one AUD registration, (c) high-frequency mixed, characterized by a mix of all four registration types, with the majority having four or more registrations and (d) crime, characterized almost entirely by criminal registrations. The highest heritability for both males and females was found for Class 3 (61% and 65%, respectively) and the lowest for Class 1 (20% for both), with shared environmental influences accounting for 10% or less of the variance in all Classes. CONCLUSIONS Using comprehensive, nationwide registry data, we showed evidence for four distinct, meaningful classes of AUD with varying degrees of heritability.
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Affiliation(s)
- E C Long
- Edna Bennett Pierce Prevention Research Center, Pennsylvania State University, 314 Biobehavioral Health Building, University Park, PA 16802, USA
| | - H Ohlsson
- Center for Primary Health Care Research, Clinical Research Center, Lund University, Box 50332, 202 13 Malmö, Sweden
| | - J Sundquist
- Center for Primary Health Care Research, Clinical Research Center, Lund University, Box 50332, 202 13 Malmö, Sweden.,Department of Family Medicine and Community Health, Department of Population Health Science and Policy, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Pl., New York, NY 10029, USA
| | - K Sundquist
- Center for Primary Health Care Research, Clinical Research Center, Lund University, Box 50332, 202 13 Malmö, Sweden.,Department of Family Medicine and Community Health, Department of Population Health Science and Policy, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Pl., New York, NY 10029, USA
| | - K S Kendler
- Virginia Institute for Psychiatric and Behavioral Genetics, Virginia Commonwealth University, 800 E. Leigh St., Biotech One, Suite 100, Richmond, VA 23219, USA.,Department of Psychiatry, Virginia Commonwealth University, 1200 East Broad St., P.O. Box 980710, Richmond, VA 23298, USA.,Department of Human and Molecular Genetics, Virginia Commonwealth University, 1101 East Marshall St., Box 980033, Richmond, VA 23298, USA
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Long EC, Verhulst B, Aggen SH, Kendler KS, Gillespie NA. Contributions of Genes and Environment to Developmental Change in Alcohol Use. Behav Genet 2017; 47:498-506. [PMID: 28714051 DOI: 10.1007/s10519-017-9858-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 06/24/2017] [Indexed: 12/01/2022]
Abstract
The precise nature of how genetic and environmental risk factors influence changes in alcohol use (AU) over time has not yet been investigated. Therefore, the aim of the present study is to examine the nature of longitudinal changes in these risk factors to AU from mid-adolescence through young adulthood. Using a large sample of male twins, we compared five developmental models that each makes different predictions regarding the longitudinal changes in genetic and environmental risks for AU. The best-fitting model indicated that genetic influences were consistent with a gradual growth in the liability to AU, whereas unique environmental risk factors were consistent with an accumulation of risks across time. These results imply that two distinct processes influence adolescent AU between the ages of 15-25. Genetic effects influence baseline levels of AU and rates of change across time, while unique environmental effects are more cumulative.
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Affiliation(s)
- E C Long
- Virginia Institute for Psychiatric and Behavioral Genetics, Virginia Commonwealth University, Richmond, VA, USA.
| | - B Verhulst
- Virginia Institute for Psychiatric and Behavioral Genetics, Virginia Commonwealth University, Richmond, VA, USA.,Department of Psychiatry, Virginia Commonwealth University, Richmond, VA, USA
| | - S H Aggen
- Virginia Institute for Psychiatric and Behavioral Genetics, Virginia Commonwealth University, Richmond, VA, USA.,Department of Psychiatry, Virginia Commonwealth University, Richmond, VA, USA
| | - K S Kendler
- Virginia Institute for Psychiatric and Behavioral Genetics, Virginia Commonwealth University, Richmond, VA, USA.,Department of Psychiatry, Virginia Commonwealth University, Richmond, VA, USA.,Department of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, VA, USA
| | - N A Gillespie
- Virginia Institute for Psychiatric and Behavioral Genetics, Virginia Commonwealth University, Richmond, VA, USA.,Department of Psychiatry, Virginia Commonwealth University, Richmond, VA, USA
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Long EC, Hill J, Luna B, Verhulst B, Clark DB. Disruptive behavior disorders and indicators of disinhibition in adolescents: The BRIEF-SR, anti-saccade task, and D-KEFS color-word interference test. J Adolesc 2015; 44:182-90. [PMID: 26277405 PMCID: PMC4632655 DOI: 10.1016/j.adolescence.2015.07.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Revised: 07/02/2015] [Accepted: 07/03/2015] [Indexed: 10/23/2022]
Abstract
Disinhibition contributes to the development of disruptive behavior disorders (DBD) in adolescents. Self-reports and behavioral tasks are commonly used to assess disinhibition, each with their unique strengths and limitations. Accordingly, it is important to identify which measure, or combination thereof, is the most effective in predicting DBD symptoms. This study assessed the relationship between DBD (symptoms of ADHD/ODD/CD) and two behavioral disinhibition tasks: the anti-saccade task and the D-KEFS color-word interference test, as well as a self-report measure (the BRIEF-SR). The results indicated that the BRIEF-Inhibit scale accounted for the majority of the variance in the DBD sum score. The anti-saccade task and color-word interference test were also significantly associated with an increase in the number of DBD symptoms endorsed. These behavioral tasks accounted for 9% additional variance than the self-report alone. Therefore, combining self-report measures with behavioral disinhibition tasks may provide the most thorough assessment of adolescent DBD.
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Affiliation(s)
- E C Long
- Behavioral Sciences Department, New Mexico Highlands University, Las Vegas, NM, USA; Virginia Institute for Psychiatric and Behavioral Genetics, Virginia Commonwealth University, Richmond, VA, USA.
| | - J Hill
- Behavioral Sciences Department, New Mexico Highlands University, Las Vegas, NM, USA.
| | - B Luna
- Western Psychiatric Institute and Clinic, University of Pittsburgh Medical Center, Pittsburgh, PA, USA.
| | - B Verhulst
- Virginia Institute for Psychiatric and Behavioral Genetics, Virginia Commonwealth University, Richmond, VA, USA.
| | - D B Clark
- Western Psychiatric Institute and Clinic, University of Pittsburgh Medical Center, Pittsburgh, PA, USA.
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Abstract
The DNA-bound orientations of Cu(II) x Xaa-Gly-L-His metallopeptides (where Xaa is Gly, L-Lys or L-Arg) were investigated by DNA fiber EPR spectroscopy and molecular modeling. Observed and calculated EPR spectra indicated that the g// axes of 1:1 Cu(II) complexes of the tripeptides tilted about 50 degrees from the DNA fiber axis. These results suggest that the complexes are stereospecifically oriented in the DNA minor groove. Although the side chain of the N-terminal amino acid residue did not affect the orientation of the DNA-bound complexes, it contributed to their stability in the presence of DNA; the Cu(II) complex of Gly-Gly-L-His was found to dissociate to hydrated Cu(II) ion more extensively than the respective L-Lys-Gly-L-His and L-Arg-Gly-L-His complexes. The ionic interaction between the positively charged lysine or arginine residues and the negatively charged DNA phosphodiester backbone may result in the reduced dissociation of these complexes when bound to the DNA minor groove.
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Affiliation(s)
- R Nagane
- Department of Applied Chemistry. Graduate School of Science and Engineering, Chuo University, Tokyo, Japan
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Affiliation(s)
- C A Claussen
- Department of Chemistry, Purdue School of Science, Indiana University Purdue University-Indianapolis, Indianapolis, Indiana 46202-3274
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Abstract
A positional-scanning combinatorial protocol was employed to optimize the deoxyribose-based cleavage of B-form DNA by Ni(II) x Xaa-Xaa-His metallopeptides. This procedure employed 18 naturally occurring amino acids (excluding Cys and Trp) to generate two libraries in which the first and second positions of the peptide ligand were varied. Increased direct DNA cleavage relative to Ni(II) x Gly-Gly-His was observed when (1) the amino-terminal peptide position contained Pro, Met, Arg, or Lys (with Pro exhibiting the greatest activity) and (2) the second peptide position contained Lys, Arg, Met, Ser, or Thr (with Lys exhibiting the greatest activity); the optimized metallopeptide, Ni(II) x Pro-Lys-His, was found to cleave DNA an order of magnitude better than Ni(II) x Gly-Gly-His. While metal complexation and the A/T-rich site selectivity of the optimized metallopeptides were not altered, DNA binding affinity was slightly increased relative to Ni(II) x Gly-Gly-His, however, not to an extent necessary to account for the observed increase in reactivity. Examination of molecular models of Ni(II) x Pro-Lys-His bound to the minor groove of DNA via hydrogen bonding of the His N3 imidazole hydrogen to the N3 of adenine or O2 of thymine suggests that the Pro residue can make hydrophobic contacts with the sugars lining the walls of the groove while the Lys residue is able to form a salt bridge with a proximal phosphate; with these interactions, the metal center is poised to abstract the C4'-H of an adjacent nucleotide suggesting that noncovalent interactions result in a positioning which contributes to increased DNA cleavage activity.
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Affiliation(s)
- X Huang
- Department of Chemistry, Purdue University School of Science, Indiana University Purdue University-Indianapolis 46202-3274, USA
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Abstract
The recognition and cleavage of tRNAPhe and the TAR RNA of HIV-1 by metallopeptides of the general form Ni(II).Xaa-Gly-His (where Xaa is Gly, Lys, or Arg) were investigated. The results of RNA cleavage analyses suggest that KHSO5- or magnesium monoperoxyphthalate-activated metallopeptides (1) induce nucleobase damage which requires aniline acetate for complete RNA strand scission and (2) selectively target the loops of stem-loop structures of the above-named substrates. In targeting RNA loop regions, the metallopeptides may be sensitive to intraloop structural features, including the overall structural environment of the loop itself and possibly the presence of intraloop hydrogen bonding. Overall, these results suggest that the metallopeptides interact selectively within a loop, in a fashion reminiscent of many RNA binding proteins, instead of targeting RNA single-stranded character alone. These observations further suggest a possible metallopeptide-based strategy for the molecular recognition of native RNA structures and insight with regard to the general features available for ligand binding site discrimination.
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Affiliation(s)
- I J Brittain
- Department of Chemistry, Indiana University Purdue University-Indianapolis 46202-3274, USA
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Abstract
Peptides representing single repeat units of the carboxy-terminal domain (CTD) of RNA polymerase II (Tyr-Ser-Pro-Thr-Ser-Pro-Ser-Tyr-NH2, 1) contain overlapping Ser-Pro-Xaa-Xaa beta-turn forming sites which permit their overall structure to closely resemble members of the quinoxaline class of antitumor DNA bisintercalators. We have modified this native sequence at the i+2 positions of each beta-turn unit by substituting Gly or D-Ala in an attempt to preorganize this structure in aqueous solution. CD and NMR spectroscopic investigations confirmed the presence of type II beta-turns within each of the substituted peptides in contrast to the native sequence which contains a relatively low population of turn structure. In addition, an examination of singly substituted peptides suggests that an increase in the population of beta-turn structure within the amino-terminal Ser-Pro-Xaa-Xaa site also increased the formation of beta-turn structure in the carboxy-terminal (unmodified) Ser-Pro-Xaa-Xaa site; in comparison, substitution in the carboxy-terminal site did not influence structure in the remaining portion of the peptide. Overall, these results suggest that the structures formed could provide unique, preorganized linkers for the construction of novel DNA-interactive bisintercalators.
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Affiliation(s)
- J R Dobbins
- Department of Chemistry, Indiana University Purdue University-Indianapolis, USA
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Long EC, Eason PD, Liang Q. Synthetic metallopeptides as probes of protein-DNA interactions. Met Ions Biol Syst 1996; 33:427-452. [PMID: 8742851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Affiliation(s)
- E C Long
- Department of Chemistry, Indiana University-Purdue University Indianapolis 46202-3274, USA
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Huang X, Shullenberger DF, Long EC. Aromatic stacking and bending of the DNA helix by the individual repeat units of the carboxy-terminal domain of RNA polymerase II. Biochem Biophys Res Commun 1994; 198:712-9. [PMID: 8297383 DOI: 10.1006/bbrc.1994.1103] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The carboxy-terminal domain (CTD) of RNA polymerase II consists of multiple repeats of the unique heptad sequence -(Ser-Pro-Thr-Ser-Pro-Ser-Tyr)- which may interact with DNA through the intercalation of adjacent tyrosine aromatic rings. We have examined details of the interaction of this motif with calf thymus DNA through analysis of peptide analogues that contain (1) an amino-terminal tyrosine which mimics the presence of an adjacent heptad repeat and (2) positively-charged lysine residues which facilitate the initial contact between peptide and DNA. Results of fluorescence experiments, NMR titrations, and viscometric analyses indicate that these peptides bind to the DNA helix through a non-classical intercalation mode involving partial aromatic stacking of the tyrosine rings with the Watson-Crick base pairs.
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Affiliation(s)
- X Huang
- Department of Chemistry, Indiana University-Purdue University at Indianapolis 46202-3274
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Abstract
Bleomycin is an antitumor agent whose activity has long been thought to derive from its ability to degrade DNA. Recent findings suggest that cellular RNA may be a therapeutically relevant locus. At micromolar concentrations, Fe(II)-bleomycin readily cleaved a Bacillus subtilis tRNAHis precursor in a highly selective fashion, but Escherichia coli tRNA(Tyr) precursor was largely unaffected even under more forcing conditions. Other substrates included an RNA transcript encoding a large segment of the reverse transcriptase from human immunodeficiency virus 1. RNA cleavage was oxidative, approximately 10-fold more selective than DNA cleavage, and largely unaffected by nonsubstrate RNAs. RNA sequence analysis suggested recognition of RNA tertiary structure, rather than recognition of specific sequences; subsets of nucleotides at the junction of single- and double-stranded regions were especially susceptible to cleavage. The ready accessibility of cellular RNAs to xenobiotic agents, the high selectivity of bleomycin action on RNAs, and the paucity of mechanisms for RNA repair suggest that RNA may be a therapeutically relevant target for bleomycin.
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Affiliation(s)
- B J Carter
- Department of Chemistry, University of Virginia, Charlottesville 22901
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Long EC, Miller PG. The medical library and the medical student. Bull Med Libr Assoc 1989; 77:356. [PMID: 16017935 PMCID: PMC227487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Affiliation(s)
- E C Long
- Duke Medical Center, Durham, North Carolina
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Long EC, Miller PG. The medical library and the medical student. Bull Med Libr Assoc 1989; 77:60. [PMID: 16017909 PMCID: PMC227303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Affiliation(s)
- E C Long
- Duke Medical Center, Durham, North Carolina
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Ehrenfeld GM, Shipley JB, Heimbrook DC, Sugiyama H, Long EC, van Boom JH, van der Marel GA, Oppenheimer NJ, Hecht SM. Copper-dependent cleavage of DNA by bleomycin. Biochemistry 1987; 26:931-42. [PMID: 2436656 DOI: 10.1021/bi00377a038] [Citation(s) in RCA: 122] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
DNA strand scission by bleomycin in the presence of Cu and Fe was further characterized. It was found that DNA degradation occurred readily upon admixture of Cu(I) or Cu(II) + dithiothreitol + bleomycin, but only where the order of addition precluded initial formation of Cu(II)--bleomycin or where sufficient time was permitted for reduction of the formed Cu(II)--bleomycin to Cu(I)--bleomycin. DNA strand scission mediated by Cu + dithiothreitol + bleomycin was inhibited by the copper-selective agent bathocuproine when the experiment was carried out under conditions consistent with Cu chelation by bathocuproine on the time scale of the experiment. Remarkably, it was found that the extent of DNA degradation obtained with bleomycin in the presence of Fe and Cu was greater than that obtained with either metal ion alone. A comparison of the sequence selectivity of bleomycin in the presence of Cu and Fe using 32P-end-labeled DNA duplexes as substrates revealed significant differences in sites of DNA cleavage and in the extent of cleavage at sites shared in common. For deglycoblemycin and decarbamoylbleomycin, whose metal ligation is believed to differ from that of bleomycin itself, it was found that the relative extents of DNA cleavage in the presence of Cu were not in the same order as those obtained in the presence of Fe. The bleomycin-mediated oxygenation products derived from cis-stilbene were found to differ in type and amount in the presence of added Cu vs. added Fe. Interestingly, while product formation from cis-stilbene was decreased when excess Fe was added to a reaction mixture containing 1:1 Fe(III) and bleomycin, the extent of product formation was enhanced almost 4-fold in reactions that contained 5:1, as compared to 1:1, Cu and bleomycin. The results of these experiments are entirely consistent with the work of Sugiura [Sugiura, Y. (1979) Biochem. Biophys. Res. Commun. 90, 375-383], who first demonstrated the generation of reactive oxygen species upon admixture of O2 and Cu(I)--bleomycin.
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Abstract
In the first 3 weeks after the 1976 earthquake in Guatemala a system for collecting, analysing, and disseminating information of medical importance was instituted in the disaster area. Data on cases of selected diseases, number of available hospital beds, and medical supplies were collected, and reported epidemics were investigated. The system functioned well despite the limited numbers of trained personnel. Collection and analysis were quick enough for data to be used immediately in decision-making. No epidemics of communicable diseases were observed in the affected area. The number of dog bites in Guatemala City increased but no cases of rabies were reported. The success of the surveillance system in Guatemala suggests that immediate use of epidemiological methods should be an integral part of disaster relief.
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Long EC. Medical specialization and world health needs. JAMA 1971; 217:1688-90. [PMID: 5109819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Long EC. Preparation of the student for education abroad. J Med Educ 1969; 44:641-647. [PMID: 5820807 DOI: 10.1097/00001888-196908000-00001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
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Spach MS, Silberberg WP, Boineau JP, Barr RC, Long EC, Gallie TM, Gabor JB, Wallace AG. Body surface isopotential maps in normal children, ages 4 to 14 years. Am Heart J 1966; 72:640-52. [PMID: 5923046 DOI: 10.1016/0002-8703(66)90347-4] [Citation(s) in RCA: 71] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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Long EC. Propaedeutics for international health. J Med Educ 1966; 41:993-998. [PMID: 5918333 DOI: 10.1097/00001888-196610000-00010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
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Abstract
Skin-electrode impedance was measured for four different types of conventional electrocardiographic electrodes applied under different conditions. All types of contacts were frequency dependent; a decrease in impedance was found with increasing frequency. Occasionally, impedance values at a frequency range of 6 to 100 cycles per second were in the tens of thousands of ohms with all electrode types. Tracings obtained under working conditions were evaluated to determine the influence of skin-electrode impedance on the recorded data. Single channel electrocardiographs accurately recorded cardiac potentials; however, simultaneously recorded multiple channel data had considerable distortion in half of the subjects. Frank vectorcardiograms demonstrated significant amplitude loss in half of the patients, with the most prominent distortion occurring in the T wave as compared to QRS. The inclusion of a buffer amplifier between the skin-electrode contacts and the resistor network produced distortionfree tracings. The inclusion of such devices is suggested to obviate any potential error produced by the highest skin-electrode impedance contact values obtained under working conditions.
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Long EC. The Placenta in Lore and Legend. Bull Med Libr Assoc 1963; 51:233-41. [PMID: 16017286 PMCID: PMC197976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Affiliation(s)
- E C Long
- Associate Professor of Physiology, Duke University Medical Center, Durham, North Carolina
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