SEARCH · PubMed Health

Results for “Data Aggregation”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 937 records · Page 52Linked to original sources

PubMed1995

Effects of lomefloxacin and sparfloxacin on human platelet aggregation.

Platelet aggregation is inhibited by high concentrations of most antibiotics. For this reason it is important to evaluate the effects of new antimicrobial agents on platelet aggregation. Lomefloxacin and sparfloxacin are new difluorinated quinolone antimicrobial agents. The aim of this work was to evaluate in vitro the effects of lomefloxacin and sparfloxacin on adenosinediphosphate (ADP) and collagen-induced human platelet aggregation. Our data showed that both antibiotics (lomefloxacin and sparfloxacin) at therapeutic doses did not inhibit in vitro human platelet aggregation. Lomefloxacin, only at the highest tested concentration (1 mg/ml), which is far higher than the clinically achievable one, significantly (P < 0.05) inhibited collagen-induced platelet aggregation. Sparfloxacin also caused inhibition of collagen and ADP-induced human platelet aggregation only at the highest tested concentration (0.01 mg/ml), which is higher than that reached in vivo. These findings suggest that therapeutic doses of lomefloxacin and sparfloxacin do not affect human platelet aggregation.

Adenosine Diphosphate↗

PubMed1999

Outcomes assessment in the NCCN: 1998 update. National Comprehensive Cancer Network.

The assessment of outcomes is a major priority of the National Comprehensive Cancer Network (NCCN). To date, the NCCN's outcomes program has (1) made a systematic inventory of member institutions' existing data sources; (2) begun a collaborative project with the National Cancer Data Bank to compare specific surgical patterns of care in NCCN institutions with national norms; and (3) begun the creation of a prospective outcomes database within the NCCN. As the first step in the database initiative, five NCCN institutions participated in a pilot project in one disease, breast cancer, aimed at developing and testing techniques of data collection, aggregation, and analysis. Six more sites were added to the pilot program in 1998. As of September 1998, data on over 1,000 unique cases had been submitted to the database, with the number of additional cases expected to triple or quadruple within the ensuing 12 months. Future plans call for (1) further expansion of the breast cancer database, both in terms of the number of institutions participating and the scope of data being collected; (2) the addition of a second disease, non-Hodgkin's lymphoma, to the database; and (3) the establishment of partnerships with other organizations for whom the database might provide useful information, such as insurers, pharmaceutical and biotechnology firms, and regulatory and accrediting bodies.

Breast Neoplasms↗

PubMed2003

Benchmarking variation in coding accuracy across the United States.

The objective of this study was to measure the consistency of coded medical data through information managers' reports of the overall coding error level in patients' medical records. Using a cross-sectional design, we examined the reported percent of records containing coding errors significant enough to change a diagnostic related group (DRG). Results indicate about 87 percent, 9 percent, and 5 percent of respondents reported that significant coding errors existed in less than 5 percent, 6-10 percent, and greater than 10 percent of the medical records in their institutions, respectively. Significant variation was found in the accuracy and consistency of coding practice and associated data quality across key demographic and organizational variables. Significantly large error rates in coded data exist in some organizations. Given variations across key demographic characteristics, providers may tend to distrust all coded data, when aggregated. As the United States moves toward an evidence-based medicine environment, the use of current patient data classification methods may be of limited value without increased attention to coding practices.

Benchmarking↗

PubMedDate not supplied

[The non-functioning chaperonin GroEL stimulates protein aggregation].

To clarify the role of chaperones in the development of amyloid diseases, the interaction of the chaperonin GroEL with misfolded proteins and recombinant prions has been studied. The efficiency of the chaperonin-assisted folding of denatured glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was shown to decrease in the presence of prions. Prions are capable of binding to GroEL immobilized on Sepharose, but this does not prevent the interaction between GroEL and other denatured proteins. The sizes of individual proteins (GroEL, GAPDH, and the recombinant prion), as well as aggregates formed after their mixing, were determined by the dynamic light scattering method. It was shown that at 25 degrees C the non-functioning chaperonin (equimolar mixture of GroEL and GroES in the absence of Mg-ATP) bound prion yielding large aggregates (greater than 400 nm). The addition of Mg-ATP decreased significantly the aggregate size to 70-80 nm. On the blocking of one of the chaperonin centers by oxidized denatured GAPDH, the aggregate size increased to 1200 nm, and the addition of Mg-ATP did not prevent the aggregation. These data indicate the significant role of chaperonins in the formation of amyloid structures and demonstrate the acceleration of aggregation in the presence of functionally inactive chaperonins. The suggested model can be used for the analysis of the efficiency of antiaggregants in the system containing chaperonins.

Amyloid↗

PubMed1985

[Aggregation of fragmented chromatin associated with the synthesis of products of its treatment with nuclease].

Isolated cell nuclei were incubated with nucleases followed by extraction of chromatin with a low salt buffer. With an increase of nuclear chromatin degradation with DNAse I or micrococcal nuclease, solubilization of deoxyribonucleoprotein (DNP) by a low salt buffer increases, reaching a maximum upon hydrolysis with 2-4% nuclear DNA and then decreases appreciably after extensive treatment with nucleases. Soluble fragmented chromatin aggregates in the course of treatment with DNAase. I. Addition to gel chromatin preparations of exogenous products of nuclease treatment of isolated nuclei leads to its aggregation. Pretreatment of nuclear chromatin with RNAase prevents solubilization of DNP by low ionic strength solutions. Some experimental data obtained with the use of severe nuclease treatment are discussed; for a correct interpretation of these data the aggregation of fragmented chromatin by products of its nuclease degradation should be taken into consideration.

Animals↗

PubMedDate not supplied

On the role of hsp72 in heat-induced intranuclear protein aggregation.

Heat treatment of cells results in an increased protein content of nuclei and nuclear matrices when isolated after the heat treatment. This increase of TX-100 insoluble protein is interpreted as being the result of protein denaturation and subsequent aggregation. After the heat treatment cells can (partly) recover from these aggregates. Recent data suggest that heat shock proteins (hsps) might be involved in the recovery (disaggregation) from these heat-induced insoluble protein complexes. In this report, the role of hsp72 in the process of aggregation and disaggregation was investigated using: non-tolerant rat-1 cells, thermotolerant rat-1 cells (rat-1 TT), and transfected rat-1 cells constitutively expressing the human inducible hsp72 gene (HR-24 cells). After heating the various cells, it was observed that the expression of the human hsp72 confers heat resistance (43-45 degrees C). Heat-induced intranuclear protein aggregation was less in HR and rat-1 TT cells as compared to nontolerant rat-1 cells. After heat treatments leading to the same initial intranuclear protein aggregation, rat-1 TT cells recovered more rapidly from these aggregates, while HR cells recovered at the same rate as nontolerant rat-1 cells. Our data suggest that increased levels of hsp72 can confer heat resistance at the level of initial (nuclear) heat damage. Elevated levels of hsp72 alone, however, do not enable cells to recover more rapidly from heat-induced intranuclear protein aggregates.

Animals↗

PubMed2004

Untangle, a tool for filtering overlapping diffraction patterns from multicrystals.

Standard crystallographic data-processing protocols are based on single-crystal models; data from aggregates of multiple crystals with different orientations are difficult to process. In certain cases, it is possible to separately index the diffraction patterns from the dominant crystals in the aggregate. Untangle is a program designed to identify and eliminate overlapping spots from such patterns in order to improve data quality. The program has a Python core with a simple and highly portable graphical user interface, permitting visual verification of the process and interactive modification of the overlap threshold. The software is available under an open-source license.

Bacterial Proteins↗

PubMed2001

How complete is AIDS surveillance in Europe? An eagle eye comparison with mortality data.

OBJECTIVES: Preliminary assessment of the adequacy of AIDS surveillance efforts in Europe by comparing data from two official sources-AIDS surveillance and mortality statistics. METHODS: The study used ENAADS (European Non-Aggregate AIDS Data Set) data compiled by the European Centre for the Epidemiological Monitoring of AIDS in St Maurice, France, and mortality statistics from WHO. As ENAADS provides information about AIDS incidence as well as AIDS mortality, both series were compared with WHO mortality data. Western European countries with more than 1000 adult AIDS cases as of July 1997 were included in the cross country comparative analyses. RESULTS: AIDS surveillance and mortality statistics in Europe depict four different patterns: (1) high overall concordance (Austria, Italy, Switzerland); (2) concordance between incidence by ENAADS and mortality by WHO, but a delay in mortality reporting in ENAADS (France, Spain); (3) more cases in WHO mortality data than in ENAADS data (Germany, Portugal); (4) more cases in ENAADS data than in WHO mortality data (Sweden, United Kingdom, Greece, Belgium). CONCLUSIONS: National AIDS surveillance systems in Europe exhibit important differences in terms of completeness and functionality. New challenges such as the introduction of effective but expensive and complex treatments will exert demands on surveillance efforts. Countries with discrepant AIDS and mortality data should try to improve and update their surveillance systems.

Acquired Immunodeficiency Syndrome↗

PubMed2005

Utilization of radiology services in the United States: levels and trends in modalities, regions, and populations.

PURPOSE: To assess the most recent available data for levels and trends in utilization of radiology procedures across populations, modalities, and geographic areas. MATERIALS AND METHODS: Aggregated claims data from Medicare enrollees for all radiology procedures and from the Medical Expenditure Panel Survey (MEPS), a nationally representative survey of almost 25 000 Americans, for some radiology procedures, were used to calculate population-based utilization for the relevant age groups. Limited private insurer data also were obtained. All radiology utilization was measured and reported, irrespective of provider specialty. Average levels and percentiles of utilization were measured according to modality, and average annual rates of increase in utilization were compared across modalities, data sources, and regions. Rates of increase in utilization according to modality and state were compared for correlation with state characteristics and initial utilization levels. RESULTS: In 2001, 4176 diagnostic and 274 therapeutic radiology procedures were performed per 1000 Medicare non-managed care enrollees. Nearly one-half of diagnostic procedures (n=2057) involved radiography. The other half involved computed tomography (CT) (n=391), magnetic resonance (MR) imaging (n=114), ultrasonography (US) (n=921), interventional radiology (n=215), mammography (n=221), and nuclear medicine (n=249). On average, between 1998 and 2001, utilization per Medicare enrollee increased 16% per year for MR imaging and 7%-15% per year for CT, US, interventional radiology, and nuclear medicine, while that for radiography increased 1% per year. The proportion of diagnostic radiology procedures performed in ambulatory settings increased from 62% in 1992 to 68% in 2001. There was wide variation across states in utilization by Medicare enrollees. State totals for diagnostic radiology were 3038 in the 10th percentile and 4573 in the 90th percentile. In 1999, MEPS reported average utilization in ambulatory settings as follows: 64 MR imaging, 102 US, 73 mammographic, 326 radiographic, and 43 radiation therapy procedures per 1000 persons (all ages) in the U.S. population. CONCLUSION: Utilization of high-technology modalities increased rapidly, while that of radiography was relatively stagnant. Variation in utilization among states and census regions was substantial.

Data Interpretation, Statistical↗

PubMed1992

The economic impact of chronic fatigue syndrome.

OBJECTIVE: To estimate the economic impact of chronic fatigue syndrome (CFS) on the individual, the government, and the community. DESIGN: The financial burden produced by CFS was studied by calculating the direct and indirect costs arising from the disorder. Data regarding use of health resources, income and employment were obtained by questionnaire from patients with CFS. In addition, aggregate Medicare data on the incidence and fees charged for each Schedule item for these patients was obtained. SETTING: The Richmond Valley, New South Wales. PARTICIPANTS: Forty-two patients with CFS identified in our population-based prevalence study. RESULTS: The conservative estimate of the per annum costs of CFS in the Richmond Valley, with a prevalence of 37.1 cases per 100,000, was $396,000. If extrapolated to the Australian population, we estimate CFS would generate an annual cost of at least $59 million. CONCLUSION: This disorder constitutes a large but neglected area of health resource utilisation and economic burden.

Adolescent↗

PubMed2002

Effects of polydispersity of chainlike aggregates on light-scattering properties and data inversion.

A systematic evaluation of the effects of polydispersity of chainlike aggregates in terms of primary particle number density and size on the scattering quantities and data inversion is presented. For aggregates with refractive index in the range absolute value(m-1) = 0.8-1.2, average size parameter x < 0.40, and primary particle number Np < 20, it is shown that the effects of polydispersity of primary particle size on the light-scattering quantities are much stronger than the polydispersity of the number of primary particles per aggregate. For aggregates with polydisperse primary particle size, the assumption of monodispersity tends to underestimate the real and imaginary parts of the refractive index and the number of primary particles. Specifically, for values of the distribution width sigma greater than 0.10, the effect of polydispersity of the size of primary particles must be considered in the data inversion schemes. Furthermore, in the same range of values for the refractive index, particle size parameter, and primary particle number, the assumption of monodispersity for aggregates with polydisperse particle number tends to underestimate the value of the real part of the refractive index and overestimate the value of the imaginary part of the refractive index and primary particle size. However, for values of the distribution width sigma less than 0.60, the effects of polydispersity of primary particle number can be neglected. In addition, the suitable pairing sets of the measured scattering quantities for data inversion are presented and discussed.

Journal Article↗

PubMed2005

Aggregation of granulocyte-colony stimulating factor in vitro involves a conformationally altered monomeric state.

Aggregation of partially folded intermediates populated during protein folding processes has been described for many proteins. Likewise, partially unfolded chains, generated by perturbation of numerous proteins by heat or chemical denaturants, have also been shown to aggregate readily. However, the process of protein aggregation from native-state conditions is less well understood. Granulocyte-colony stimulating factor (G-CSF), a member of the four-helix bundle class of cytokines, is a therapeutically relevant protein involved in stimulating the growth and maturation of phagocytotic white blood cells. Under native-like conditions (37 degrees C [pH 7.0]), G-CSF shows a significant propensity to aggregate. Our data suggest that under these conditions, native G-CSF exists in equilibrium with an altered conformation, which is highly aggregation prone. This species is enriched in 1-2 M GdmCl, as determined by tryptophan fluorescence and increased aggregation kinetics. In particular, specific changes in Trp58 fluorescence report a local rearrangement in the large loop region between helices A and B. However, circular dichroism, reactivity toward cyanylation, and ANS binding demonstrate that this conformational change is subtle, having no substantial disruption of secondary and tertiary structure, reactivity of the free sulfhydryl at Cys17 or exposure of buried hydrophobic regions. There is no indication that this altered conformation is important to biological activity, making it an attractive target for rational protein stabilization.

Biophysical Phenomena↗

PubMed1993

Unraveling the web of personality judgments: the influence of social networks on personality assessment.

Contemporary assessment models have focused on the degree to which self- and other reports of personality description agree in an effort to define consensus and agreement about personality attributes. In general, we believe that analyses of this type of data have been limited in that they tend to focus on both simple models (usually dyad-based) and simple aggregations of data (usually correlations between self- and other ratings). In addition, the behaviors used as stimuli in experimental settings lack the richness of behaviors in natural social settings. Here, we present some ideas from social network models in an effort to influence broader conceptualizations of agreement and consensus in assessment. Social network models provide a more complete description of interpersonal behavior beyond the dyadic level in both laboratory and natural settings. After defining some basic social network concepts, we go on to suggest the applicability of these concepts to personality assessment and, more specifically, to how these models might be used to study self-other agreement and consensus about personality judgments. Empirical data are used to illustrate social network concepts in the domain of personality assessment.

Female↗

PubMed1989

Inhibition of platelet activating factor-induced platelet aggregation by molsidomine, SIN-1, and nitrates in vitro and ex vivo.

We compared in vitro the effects of molsidomine, its active metabolite SIN-1, sodium nitroprusside, and the organic nitrates nitroglycerin, isosorbide-5-mononitrate, and isosorbide-2,5-dinitrate on platelet aggregation induced by platelet activating factor and on the activity of soluble guanylate cyclase. In addition, the effects of molsidomine and of isosorbide-5-mononitrate on ex vivo platelet function were studied. In vitro, SIN-1 and sodium nitroprusside were about 100-fold more potent activators of platelet guanylate cyclase and inhibitors of platelet activating factor-induced aggregation than the other agents. In contrast, in ex vivo experiments, not only molsidomine but also isosorbide-5-mononitrate inhibited platelet activating factor-induced aggregation. These data indicate that molsidomine, SIN-1, and organic nitrates can in vivo, like endothelium-derived relaxing factor, inhibit platelet aggregation and exert antithrombotic properties, although nitrates apparently cannot be converted in platelets to active metabolites. Since the antiaggregatory properties are observed when platelet activating factor is used as an aggregant, and since platelet activating factor-induced aggregation is only weakly influenced by inhibitors of cyclo-oxygenase, this effect might be useful clinically.

Cyclic GMP↗

PubMed2005

Novel protein markers of acute coronary syndrome complications in low-risk outpatients: a systematic review of potential use in the emergency department.

BACKGROUND: Published literature was systematically reviewed to determine the diagnostic accuracy of new protein markers of acute coronary syndromes (ACS) in symptomatic outpatients at low risk of ACS and related complications comparable to patients evaluated in emergency department chest pain units. METHODS: Studies were identified by a MEDLINE (1966 to May week 3, 2005) search. Abstracts were reviewed for relevance, and manuscripts were included by the independent consensus of 2 observers based on explicit criteria restricting the analysis to studies relevant to screening ambulatory patients with symptoms suggesting ACS. Publication bias was identified by a modified funnel plot analysis [study size (y) vs the inverse of the negative likelihood ratio (x)]. Results of individual markers were reported separately. When 3 or more eligible studies were identified, data were aggregated by use of the summary ROC (SROC) curve. RESULTS: Twenty-two protein markers in 10 unique populations met the inclusion criteria. Data required for SROC analysis (true- and false-positive rates) were available for 17 markers, in 9 unique populations, from publications and personal communications. Of these, only C-reactive protein was published in more than 2 populations to allow aggregation (6 studies total). C-Reactive protein demonstrated poor diagnostic performance on SROC curve analysis, with an area under the curve of 0.61 and a pooled diagnostic odds ratio of 1.81 (95% confidence interval, 1.06-3.07). CONCLUSION: Published evidence is not sufficient to support the routine use of new protein markers in screening for ACS in the emergency department setting.

Acute Disease↗

PubMed1975

Amino acids and collagen-induced platelet aggregation. Lack of effect of three amino acids that are elevated in homocystinuria.

Arterial thrombosis frequently occurs in homocystinuric children whose plasma levels of homocystine, homocysteine, and methionine are elevated. Since platelet aggregation is important in the pathogenesis of arterial thrombosis, we wondered whether the elevated concentrations of these amino acids might predispose to arterial thrombosis by enhancing platelet aggregation. Addition of the above amino acids to normal platelet-rich plasma to achieve concentrations within or above the range found in homocystinuric children had no effect on collagen-induced platelet aggregation. These data give no support to the hypothesis that the arterial thromboses of homocystinuric children are a result of enhancement of platelet aggregation by homocystine, homocysteine, or methionine.

Collagen↗

PubMed1987

Inhibition of platelet aggregation by unsaturated fatty acids through interference with a thromboxane-mediated process.

cis- and trans-unsaturated fatty acids with 18 carbon atoms (oleic, linoleic, elaidic and linolelaidic acid) inhibited aggregation of washed rabbit platelets stimulated with collagen, arachidonic acid and U46619 when in the same concentration ranges. Thrombin-induced aggregation was not affected by any of them. Saturated fatty acid (stearic acid) had no effect on this response. The inhibition is independent of the induced change in membrane fluidity, since trans-isomers could not induce the change in fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene. Unsaturated fatty acids, except linoleic acid, did not interfere with the formation of thromboxane B2 from exogenously added arachidonic acid. All the unsaturated fatty acids only slightly inhibited the arachidonic acid liberation by phospholipase A2 in platelet lysate. This indicates that the unsaturated fatty acids may block a process after formation of thromboxane A2 in response to collagen and arachidonic acid. The increase in phosphatidic acid formation stimulated with U46619 was inhibited dose dependently by each of the unsaturated fatty acids but that stimulated with thrombin was not affected by any of them. Phospholipase C activity measured by diacylglycerol formation in unstimulated platelet lysate was not inhibited by the fatty acids. The elevation of cytosolic free Ca2+ induced by arachidonic acid or U46619 and Ca2+ influx by collagen were inhibited almost completely at the same concentration as that which inhibited their aggregation. These data suggest that the unsaturated fatty acids were intercalated into the membrane and inhibited collagen- and arachidonic acid-induced platelet aggregation by causing a significant suppression of the thromboxane A2-mediated increase in cytosolic free Ca2+, probably due to interference with the receptor-operated Ca2+ channel.

Animals↗

PubMed2005

Fibrinogen surface distribution correlates to platelet adhesion pattern on fluorinated surface-modified polyetherurethane.

In previous work, it had been shown that platelet adhesion could be reduced by fluorinating surfaces with oligomeric fluoropolymers, referred to as surface-modifying macromolecules (SMMs). In the current study, two in vitro blood-contacting experiments were carried out on a polyetherurethane modified with three different SMMs in order to determine if altered platelet adhesion levels could be related to the pattern of adsorbed protein and more specifically to the manner in which fibrinogen (Fg) distribution occurs at the surface. In the first experiment, the materials were placed in whole human blood and the adherent platelets were viewed with high-resolution scanning electron microscopy (SEM). In a second experiment, the materials were incubated with human plasma with the absence of platelets. The plasma contained 5% fluorescent-Fg. The materials were then viewed with a fluorescence microscope and images were collected to define the distribution of high-density fluorescent-Fg areas. The SEM and fluorescent-Fg images were imported to Image Pro Plus imaging software to measure the area, length and circularity and a bivariate correlation test was conducted between the two sets of data. For area and length morphology parameters, there were high and significant correlations (r > 0.9, p < 0.05) between the platelets and Fg aggregates. The data suggest that the Fg distribution may serve as a predictor of platelet morphology/activation and provides insight into the non-thrombogenic character of biomaterials containing the fluorinated SMMs.

Adsorption↗