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PubMed2000

Neither phosphorylation nor the amino-terminal part of rabies virus phosphoprotein is required for its oligomerization.

Rabies virus (PV strain) phosphoprotein (P) was expressed in bacteria. This recombinant protein binds specifically to the nucleoprotein-RNA complex purified from infected cells. Chemical cross-linking and gel-filtration studies indicated that the P protein forms oligomers. Analytical centrifugation data demonstrated the co-existence of monomeric and oligomeric forms of rabies virus P protein and suggested that there is an equilibrium between these species. As P expressed in bacteria is not phosphorylated, this result indicates that P phosphorylation is not required for its oligomerization. Although an alignment of several rhabdovirus P sequences revealed that the amino-terminal domain of P has a conserved predicted propensity to form helical coiled coils, an amino-terminally truncated form of P protein, lacking the first 52 residues, was also shown to be oligomeric. Therefore, the amino-terminal domain of rabies virus P is not necessary for its oligomerization.

Amino Acid Sequence↗
PubMed2001

Extremal principle for the steady-state selection in driven lattice gases with open boundaries.

This paper investigates the steady states of one-dimensional driven lattice gases with open boundary conditions. It shows how the extremal principle proposed recently by Popkov and Schütz can be modified to apply to more general cases. Monte Carlo simulations are presented for a one-dimensional totally asymmetric simple exclusion process with nearest neighbor repulsion under parallel update as an example. The simulations enable one to guess the exact phase diagram for this particular lattice gas with deterministic bulk dynamics, by fitting the data to analytic formulas, which appear to be exact in the thermodynamic limit.

Journal Article↗
PubMed2006

Direct method to study membrane rigidity of small vesicles based on atomic force microscope force spectroscopy.

Mechanical properties of lipidic membranes such as their bending rigidity are governing liposome morphology and play an important role in processes like membrane fusion and adhesion. Force versus deformation measurements are the most direct means to determine this, but so far experimental data is scarce and mainly stems from techniques that are limited to giant vesicles. We present atomic force microscope force spectroscopy as a method allowing force-deformation measurements of submicron vesicles. Bending rigidities of small unilamellar dipalmitoylphosphatidylcholine (DPPC) liposomes (R<200 nm) can be derived from the force-deformation data using analytical models based on shell theory and are in good agreement with independent measurements.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed2001

Theory of extraordinary optical transmission through subwavelength hole arrays.

We present a fully three-dimensional theoretical study of the extraordinary transmission of light through subwavelength hole arrays in optically thick metal films. Good agreement is obtained with experimental data. An analytical minimal model is also developed, which conclusively shows that the enhancement of transmission is due to tunneling through surface plasmons formed on each metal-dielectric interface. Different regimes of tunneling (resonant through a "surface plasmon molecule," or sequential through two isolated surface plasmons) are found depending on the geometrical parameters defining the system.

Journal Article↗
PubMed2004

Nonrelativistic QED approach to the bound-electron g factor.

Within a systematic approach based on nonrelativistic quantum electrodynamics, we derive the one-loop self-energy correction of order alpha(Z alpha)(4) to the bound-electron g factor. In combination with numerical data, this analytic result improves theoretical predictions for the self-energy correction for carbon and oxygen by an order of magnitude. Basing on one-loop calculations, we obtain the logarithmic two-loop contribution of order alpha(2)(Z alpha)(4)ln([(Z alpha)(-2)] and the dominant part of the corresponding constant term. The results obtained improve the accuracy of the theoretical predictions for the 1S bound-electron g factor and influence the value of the electron mass determined from g-factor measurements.

Journal Article↗
PubMed1971

Preparation and purification of glucanase and chitinase from bean leaves.

Glucanase (endo-beta-1, 3-glucan 3-glucanohydrolase, EC 3.2.1.6, laminarinase, callase) and chitinase (poly-beta-1, 4-[2-acetamido-2-deoxy] -d-glucoside glycanohydrolase, EC 3.2.1.14) were extracted from ethylene-treated bean (Phaseolus vulgaris L. cv. Red Kidney) leaves and purified on hydroxyapatite and carboxymethyl Sephadex columns. The glucanase prepared was homogeneous as judged by analytical centrifugation data, electrophoresis, and antibody-antigen reactions. On the basis of gel filtration, antibody-antigen reactions, and amino acid analysis, the molecular weight was estimated to be between 11,500 and 12,500. However, ultracentrifugation gave a higher estimate of 34,000. The glucanase had an isoelectric point near pH 11 and was specific for beta-1, 3-linkages. The chitinase was only partially purified as judged by electrophoretic behavior.

Journal Article↗
PubMed2006

Temperature-induced reversible conformational change in the first 100 residues of alpha-synuclein.

Natively disordered proteins are a growing class of anomalies to the structure-function paradigm. The natively disordered protein alpha-synuclein is the primary component of Lewy bodies, the cellular hallmark of Parkinson's disease. We noticed a dramatic difference in dilute solution 1H-15N Heteronuclear Single Quantum Coherence (HSQC) spectra of wild-type alpha-synuclein and two disease-related mutants (A30P and A53T), with spectra collected at 35 degrees C showing fewer cross-peaks than spectra acquired at 10 degrees C. Here, we show the change to be the result of a reversible conformational exchange linked to an increase in hydrodynamic radius and secondary structure as the temperature is raised. Combined with analytical ultracentrifugation data showing alpha-synuclein to be monomeric at both temperatures, we conclude that the poor quality of the 1H-15N HSQC spectra obtained at 35 degrees C is due to conformational fluctuations that occur on the proton chemical shift time scale. Using a truncated variant of alpha-synuclein, we show the conformational exchange occurs in the first 100 amino acids of the protein. Our data illustrate a key difference between globular and natively disordered proteins. The properties of globular proteins change little with solution conditions until they denature cooperatively, but the properties of natively disordered proteins can vary dramatically with solution conditions.

Amino Acids↗
PubMed1984

Biosynthesis of the 09 antigen of Escherichia coli. Core structure of rfe mutant as indication of assembly mechanism.

The chemical structure of the outer (hexose) regions of the core oligosaccharide from Escherichia coli 09 with the complete R1 core, and from a R1-derived rfe mutant were analyzed using compositional analysis, methylation and gas chromatography/mass spectrometry. It was found that, in contrast to the branched outer region of the R1 core, the outer region of the core from the rfe mutant lacked terminal glucose and was linear. These results are in agreement with recent findings on the biosynthesis of the 09 antigen. They suggest a cotransfer of glucose with the 09-specific mannan to a 'pre-core' lacking terminal glucose, as the assembly (translocation) step in the 09 antigen synthesis. Thus it is suggested that the initiation of O-chain synthesis (by the formation of an acceptor glucolipid ) and the termination of core synthesis are closely correlated. In conjunction with previous biochemical data, the analytical results presented here indicate a novel core synthesis.

Antigens, Bacterial↗
PubMed2004

When 'go' and 'nogo' are equally frequent: ERP components and cortical tomography.

In human electrophysiology, a considerable corpus of studies using event-related potentials have investigated inhibitory processes by employing the 'go-nogo' paradigm, which requires responding to one type of event while withholding the response to another type of event. Two event-related potential waveform features (N2 and P3) have been associated with larger amplitude in nogo trials than in go trials. Traditionally, these differences were thought to reflect response inhibition. Recently, the source localization of N2 to the anterior cingulate cortex, as well as the colocalization of N2 with error-related negativity, has been interpreted in terms of conflict monitoring. In order to isolate the contribution of inhibitory processes, we matched the frequency of the go and nogo events, thus minimizing differences in response conflict between event types. A data-driven analytical procedure contrasted go with nogo events across the entire event-related potential segment and found that N2 reliably differentiated between the two conditions while P3 did not. Tomographical analyses of the N2 difference observed in conditions of equal go and nogo trial frequency localized N2 to the right ventral and dorsolateral prefrontal cortex. Because a growing body of evidence implicates these brain regions in inhibitory processes, we conclude that N2 does, at least in part, reflect inhibition.

Adolescent↗
PubMed2005

Epidemiology of nocturia.

The incidence of nocturia episodes increases with age and is associated with interrupted sleep and distress. There are no large differences in the incidence of nocturia between men and women, but young women tend to have it more frequently than young men, and very old men have it more often than very old women. The International Continence Society has defined nocturia as 'the number of voids recorded during a night's sleep: each void is preceded and followed by sleep.' This simple and useful definition should facilitate further epidemiological study of nocturia. Although there are many direct prevalence studies of nocturia, there is a great need for more advanced analytical epidemiological data on risk factors and comorbidity. Clinicians should question patients about nocturia and should consider this symptom in a broader sense than in its traditional association with benign prostatic obstruction in men and incontinence in women. There are several classic studies of nocturia. The nature of future epidemiological research will depend on the resolution of several methodological issues. Further evaluation of nocturia is warranted because of its high incidence among the general adult population.

Adult↗
PubMed1995

Integration of gene maps: updating chromosome 1.

The first integrated map of chromosome 1 was published in 1992. We present an updated summary map of 371 loci constructed from a location database that includes physical and genetic data. The summary map subsumes a composite physical location, sex-specific genetic location, cytogenetic assignment, mouse homology, rank and references to physical maps. The genetic length is 208 cM for the male map, in close agreement with the chiasma map, and 371 cM for the female map. There is evidence for a high level of interference on chromosome 1. The location database comprising both data and analytical software is discussed in relation to alternative approaches and possible enhancements.

Algorithms↗
PubMed2006

Implications of excessive precision for risk comparisons: lessons from the past four decades.

This article reviews five published "second-order" risk comparisons from the past four decades that implied precise understanding, and hence clear relationships or orderings, of the underlying risks. "Second order" here refers to efforts that extract information from original sources with the goal of relating diverse findings. All five of these publications have frequently been cited in the peer-reviewed literature and/or in risk regulatory debate in the United States. Each is associated with at least one contemporaneous critique that the findings were excessively precise. None of these critiques suggested that an alternative relationship or ordering of the risks evaluated was more appropriate. Instead, each critique concluded that alternative, contradictory relationships were at least as plausible given data and/or analytical limitations. In one case, the critique led to the withdrawal of the original publication. The original findings have been propagated or used uncritically in subsequent literature, including political support for cost-effectiveness analysis. In other cases, the critiques have been used to discredit quantitative risk analysis in general, especially in the cases of nuclear power and cost-benefit analysis. Both of these outcomes are undesirable. Future risk comparisons should avoid excessive precision, include explicit discussion of uncertainty, and differentiate between plausible estimates and expected values.

Journal Article↗
PubMed1999

Assessment of the "scholarly project" requirement for emergency medicine residents: report of the SAEM Research Directors' workshop. SAEM Research Directors' Interest Group.

OBJECTIVES: Differences in interpretation of the residency review committee (RRC) directive concerning resident scholarly activity have resulted in inconsistencies in the practical fulfillment of this responsibility among the various training programs in emergency medicine. During a workshop organized by the SAEM Research Directors' Interest Group (RDIG), a consensus statement was developed regarding the scope, definition, and purpose of the scholarly project requirement. METHODS: During the workshop, the NIH model of consensus building was used to develop statements pertaining to specific questions of the goals, definition, and endpoints of the scholarly project. The program consisted of an overview of the history and issues related to the scholarly project and presentations of varying viewpoints from interested parties. A final consensus of answers to the defined questions was then developed by the workshop participants during roundtable discussions and further refined through interactive debate using the RDIG e-mail list server. RESULTS: By consensus it was agreed that the primary role of the scholarly project is to instruct residents in the process of scientific inquiry, to teach problem-solving skills, and to expose the resident to the mechanics of research. To realize these goals, the project should include the general elements of hypothesis formulation, data collection, analytic thinking, and interpretation of results. It was also thought that these elements should be documented in some written form with a literature review. CONCLUSIONS: While each residency program must implement the RRC residency requirements in a manner that best suits the needs and culture of its individual environment, a concurrence of definition and approach to satisfying the scholarly project requirement would provide better consistency in resident training. Guidelines developed by consensus during the SAEM RDIG workshop may serve as a general recipe that can be used to fulfill the goals of the scholarly project and the spirit of the RRC directive.

Decision Making↗
PubMed2026

Artificial Intelligence Technologies in Nursing Clinical Decision-Making: An Umbrella Review.

AIM: To describe contemporary peer-reviewed literature on artificial intelligence in nurses' clinical decision-making. METHODS: An umbrella review of literature reviews. DATA SOURCES: Four major databases were searched for reviews published between 2019 and 2024. RESULTS: Sixteen literature reviews reported on 965 nursing artificial intelligence primary studies. The studies focused on technology development and emerging performance evaluations, whilst real-world testing or implementation in nursing clinical settings was rare. Rigorous comparative analyses were lacking. While artificial intelligence demonstrates promise in decision-making, challenges such as a lack of controlled studies, algorithmic bias, limited reproducibility and insufficient clinical trials hinder its practical impact. Ethical concerns, transparency and patient data privacy issues pose barriers to AI integration in nursing practice. Ethical and legal guidelines for patient privacy are needed and should be taught along with AI literacy training for nurses. CONCLUSIONS: Artificial intelligence has the potential to enhance clinical nursing decision-making, although evidence is limited by too few examples of nurse participation during development. Underutilisation in administrative nursing functions hinders implementation. Nurses should assume a central role in the design and development of AI applications to ensure that these technologies address the realities of nursing practice. With such improvements, artificial intelligence can transform nursing practice, improve nurses' clinical decision-making and ultimately enhance consumer healthcare outcomes. PATIENT OR PUBLIC INVOLVEMENT: No Patient or Public Involvement. REPORTING METHOD: While there is no reporting checklist for umbrella reviews, the PRISMA guide for systematic reviews was followed.

Artificial Intelligence↗
PubMed2005

Tilted plane Feldkamp type reconstruction algorithm for spiral cone beam CT.

An approximate image reconstruction method for spiral cone beam computed tomography (CT), called tilted plane Feldkamp type reconstruction algorithm (TPFR), is presented in this paper, which extends Feldkamp cone beam reconstruction algorithm to deal with its inaccuracy and artifact problems caused by large cone angle. This is done by tilting the reconstructing planes to minimize the cone angle and optimally fit the spiral segment of the source. The tilted plane image reconstruction requires reforming the three-dimensional projection data set for the tilted plane and application of Feldkamp algorithm to the reformed data set. Analytical and computational results can show that the image reconstruction performance of the proposed TPFR algorithm is superior to that of the Feldkamp reconstruction algorithm in the image quality, volume coverage speed, maximum achievable pitch value, and slice sensitivity profiles. Moreover, it provides more accurate image reconstruction than the existing two-dimensional reconstruction algorithms.

Algorithms↗
PubMed2004

Optimal search strategies for retrieving systematic reviews from Medline: analytical survey.

OBJECTIVE: To develop optimal search strategies in Medline for retrieving systematic reviews. DESIGN: Analytical survey. DATA SOURCES: 161 journals published in 2000 indexed in Medline. MAIN OUTCOME MEASURES: The sensitivity, specificity, and precision of retrieval of systematic reviews of 4862 unique terms in 782,485 combinations of one to five terms were determined by comparison with a hand search of all articles (the criterion standard) in 161 journals published during 2000 (49,028 articles). RESULTS: Only 753 (1.5%) of the 49,028 articles were systematic reviews. The most sensitive strategy included five terms and had a sensitivity of 99.9% (95% confidence interval 99.6% to 100%) and a specificity of 52% (51.6% to 52.5%). The strategy that best minimised the difference between sensitivity and specificity had a sensitivity of 98% (97% to 99%) and specificity of 90.8% (90.5% to 91.1%). Highest precision for multiterm strategies, 57% (54% to 60%), was achieved at a sensitivity of 71% (68% to 74%). The term "cochrane database of systematic reviews.jn." was the most precise single term search strategy (sensitivity of 56% (52% to 60%) and precision of 96% (94% to 98%)). These strategies are available through the "limit" screen of Ovid's search interface for Medline. CONCLUSIONS: Systematic reviews can be retrieved from Medline with close to perfect sensitivity or specificity, or with high precision, by using empirical search strategies.

Information Storage and Retrieval↗
PubMed2005

Optimal search strategies for retrieving scientifically strong studies of treatment from Medline: analytical survey.

OBJECTIVE: To develop and test optimal Medline search strategies for retrieving sound clinical studies on prevention or treatment of health disorders. DESIGN: Analytical survey. DATA SOURCES: 161 clinical journals indexed in Medline for the year 2000. MAIN OUTCOME MEASURES: Sensitivity, specificity, precision, and accuracy of 4862 unique terms in 18 404 combinations. RESULTS: Only 1587 (24.2%) of 6568 articles on treatment met criteria for testing clinical interventions. Combinations of search terms reached peak sensitivities of 99.3% (95% confidence interval 98.7% to 99.8%) at a specificity of 70.4% (69.8% to 70.9%). Compared with best single terms, best multiple terms increased sensitivity for sound studies by 4.1% (absolute increase), but with substantial loss of specificity (absolute difference 23.7%) when sensitivity was maximised. When terms were combined to maximise specificity, 97.4% (97.3% to 97.6%) was achieved, about the same as that achieved by the best single term (97.6%, 97.4% to 97.7%). The strategies newly reported in this paper outperformed other validated search strategies except for two strategies that had slightly higher specificity (98.1% and 97.6% v 97.4%) but lower sensitivity (42.0% and 92.8% v 93.1%). CONCLUSION: New empirical search strategies have been validated to optimise retrieval from Medline of articles reporting high quality clinical studies on prevention or treatment of health disorders.

Information Storage and Retrieval↗