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At least 379 records · Page 21Linked to original sources
PubMed2002

Flow cytometric evaluation of adhesion of Streptococcus pyogenes to epithelial cells.

The precise roles of various surface molecules in the attachment of Streptococcus pyogenes to host epithelia are currently unclear. A flow cytometry assay that facilitates the analysis of the kinetics of S. pyogenes adhesion to epithelial cells was developed. Dose- and time-dependent adhesion isotherms with both buccal epithelial cells (BECs) and Hep-2 cells as substrata were obtained. Although binding equilibrium is reached within 2 h on both cell types, saturation of binding sites on BECs is not achieved within a wide range of experimental conditions. This indicates a high degree of non-specific attachment to that cell type. Since no rinsing step is necessary when using flow cytometry to analyze adhesion, low-affinity associations were observable. This was confirmed by determining bacterial desorption rates early and late in the adsorption process. Binding irregularities were also easily detected since the cytometer records and displays data for up to 10,000 epithelial cells per time point. It is proposed to use this methodology to assign roles to particular surface molecules/characteristics during distinct phases of adhesion.

Bacterial Adhesion↗
PubMed1998

Box and whisker plots for graphic presentation of audiometric results of conductive hearing loss treatment.

The Committee on Hearing and Equilibrium of the American Academy of Otolaryngology-Head and Neck Surgery has published guidelines for the reporting of audiometric results of middle ear interventions. It recommends the reporting of several audiometric variables by means of two summary parameters: means and standard deviation. This article advocates the use of other summary statistics, namely the median, quartiles, and extremes, because they do not require a normal distribution of the audiometric data and they are not sensitive to variations of the extreme values. On the basis of the exploratory data analysis, we propose a graphic method to present the Committee's variables in terms of their summary statistics. This "multiple box and whisker plot" offers a detailed and accurate overview of six variables in one graph.

Audiometry↗
PubMed2003

[Use of statistical analysis in original articles in "Actas Urológicas Españolas." Accessibility for the reader].

OBJECTIVES: To describe the use of statistical methods employed in original articles published in Actas Urológicas Españolas as the first step to quantify the accessability for the readers. METHODS: Observational, retrospective, descriptive and transversal study to analize all the original articles published in Actas Urológicas Españolas during the year 2000. Once the anectotic cases were excluded, 55 original studies were selected. In each article it was minuciously reviewed the methods and results sections, tables and figures included, to identify the statistical analysis used and to classify them into 18 categories with three accessability levels as Emerson and Colditz and Mora y cols, previously reported: descriptive statistics, bivariables analysis and complex analysis. A randomized sample of the originals were reviewed again by the same investigator three months later to evaluate the criteria liability. The accessability was defined as a) article dependent (rate of originals that readers with different statistical knowledge are able to understand) and b) analysis dependent (rate of statistical methods respect to the total performed overall the articles that readers are able to understand). RESULTS: Our major findings are that the more frequently used technics are descriptive analysis (39.3%), bivariable tables (12.1%), survival analysis (10%), t Student and z tests (6%), and nonparametric tests (8.6%). The accessability for a reader which statistical konowledge includes bivariable methods is 63.6% (IC 95% 49%-76%) and 79% (IC 95% 71%-85), article and analysis dependent respectively, rates that are similar to the reported for biomedical journals in our country. CONCLUSIONS: A great percentage of original articles in Actas Urológicas Españolas includes complex analysis. It could be good that readers were able to increase our statistical and methodological knowledge to perform a critical approach to our publication.

Bibliometrics↗
PubMed2001

Quantitative analysis of PC MRI velocity maps: pulsatile flow in cylindrical vessels.

The accuracy of MR phase contrast (PC) velocity mapping, and the subsequent derivation of wall shear stress (WSS) values, has been quantitatively assessed. Using a retrospectively gated PC gradient-echo technique, the temporal-spatial velocity fields were measured for pulsatile flow in a rigid cylindrical vessel. The experimental data were compared with values derived from the Womersley solution of the Navier-Stokes equations. For a sinusoidal waveform, the overall root-mean-square (rms) difference between the measured and analytical velocities corresponded to 13% of the peak fluid velocity. The WSS derived from the data displayed a 14% rms difference with the analytical model. As an example of a more complicated flow, a triangular saw-tooth waveform was deconstructed into its Fourier components. Velocity maps and the WSS were calculated by the superposition of the individual solutions, weighted by the Fourier series coefficient, for each harmonic. The velocity and experimentally derived WSS agreed with the analytical results (4% and 12% rms difference, respectively). Evaluation of the analytical models allowed an estimate of the inherent accuracy in the measurement of velocity maps and WSS values.

Arteriosclerosis↗
PubMed1997

A user-friendly method for calibrating a subcutaneous glucose sensor-based hypoglycaemic alarm.

A crucial step in developing a glucose monitoring system using a subcutaneous implanted glucose sensor is the transformation of the sensor signal (a current) into an estimation of a blood glucose concentration. We have developed an Electronic Control Unit (ECU) able to recognize, before and after a glucose load, that the sensor current presents a plateau, thus triggering an alarm asking for blood glucose determination. The system, fed with these results, subsequently transforms the current into an estimation of glucose concentration by linear extrapolation based on the sensor sensitivity and the background current computed from the two sets of current and glycaemia values (two-point calibration). In addition, the system is able to trigger an alarm when this estimation decreases below a threshold that can be set by the user. This system was evaluated in experiments performed in 12 normal rats. The quality of the calibration was assessed by comparing, by error grid analysis, the data displayed on the liquid-crystal display of the ECU to concomitant plasma glucose concentration determined at frequent intervals, 65 +/- 6 and 26 +/- 5% of the values were in zones A (good) and B (acceptable estimation) of the grid, respectively. The system was set to trigger an alarm when the estimation of glucose concentration decreased below 70 mg/dl. Following an insulin administration, the alarm was triggered when the system displayed a 64 +/- 2 mg/dl glucose concentration. The concomitant plasma glucose concentration was 59 +/- 5 mg/dl (NS). In conclusion, this work validates experimentally the new, user-friendly method for calibrating the glucose sensor integrated into the ECU, based on an automatic detection of plateaus. The quality of the sensor calibration performed with this procedure is compatible with the appropriate functioning of this continuous glucose monitoring system, which was demonstrated by its ability to detect mild hypoglycaemia following insulin injection.

Animals↗
PubMed1995

Performance feedback increases the incidence of handwashing by staff following patient contact in intensive care.

Nosocomial infections affect up to 30% of ICU patients. Although infection rates decline with increasing handwashing frequency, handwashing rates in ICU's are poor. This study investigated the hypotheses that the subjects' profession would not influence, and performance feedback would not increase, the incidence of handwashing post-patient contact. The study involved an initial period of covert observation to record the baseline level of handwashing, followed by a period of overt observation with regular feedback on handwashing performance by means of letters to staff and histograms of the data displayed in the ICU. Handwashing incidence was reassessed 6 months after performance feedback had ceased. Handwashing differed significantly between professions (P = 0.0001). Initially, the incidence of handwashing was highest amongst wardsmen (90%) and lowest amongst Visiting Medical Officers (VMOs) (20%). Sixty-nine percent (69%) of Registered Nurses (RNs), 57% of physiotherapists, 41% of Resident Medical Officers (RMOs) and 35% of radiographers washed their hands after touching patients. With the exception of the wardsmen, there was a trend towards an increased frequency in handwashing in all groups after performance feedback, but the differences were only statistically significant in the VMO and physiotherapist groups (P < 0.001). The improvements were maintained for 6 months after the feedback phase ended in 4 of the 6 groups.

Critical Care↗
PubMed1998

Multi-anode detection in electrospray ionization time-of-flight mass spectrometry.

An electrospray ionization ion source coupled to a time-of-flight mass analyzer incorporating a multi-anode time-to-digital converter is described. High-speed data acquisition (kHz mass spectral acquisition) rates are achieved. The four-anode detector produces a significant increase in detection/counting efficiency over that for a single-anode detector. In this work a 2.5 times increase in detection efficiency is demonstrated. The multi-anode detector is also used as a diagnostic tool to optimize transmission of the ion optics.

Cytochrome c Group↗
PubMed2003

Chronically ill adolescents' experiences of communicating with doctors: a qualitative study.

PURPOSE: To explore the experiences of chronically ill adolescents in communicating with health professionals, including the identification of factors which hinder or facilitate their use of health professionals as an information source. METHODS: 63 adolescents (11-16 years) with a chronic condition (cystic fibrosis, diabetes, epilepsy, juvenile chronic arthritis, or Duchenne muscular dystrophy) were interviewed, and subsequently took part in two group discussion meetings with other adolescents of a similar age with the same condition. Data were analyzed using the framework method involving data reduction, data display, and conclusion-drawing and verification. RESULTS: Factors affecting the openness and effectiveness of communication included: duration and frequency of contact; gender; perceived attitudes towards adolescents; the communication skills of the adolescent and health professional; and the presence of parents and medical students/trainee doctors. The type of information needed also affected whether the adolescents felt able to discuss an issue with a health professional. Adolescents were reluctant to raise personal or sensitive issues or to ask questions that revealed poor adherence. A perceived lack of interest in the wider impacts of having a chronic condition on day-to-day life was also a barrier to adolescents discussing difficulties at school and socio-emotional problems. CONCLUSIONS: Communication and information provision are key roles for health professionals, yet this study highlights a population with potentially high levels of information need who are facing considerable barriers to addressing these needs. Steps taken to improve adolescent-health professional communication need to address a range of practical, attitudinal and behavioral factors.

Adolescent↗
PubMed2002

Using control charts to assess performance measurement data.

BACKGROUND: In 1997 the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) announced the ORYX initiative, which integrates outcomes and other performance measurement data into the accreditation process. JCAHO uses control and comparison charts to identify performance trends and patterns that are provided to JCAHO surveyors in advance of the organization's survey. During its survey, the health care organization (HCO) is asked to explain its rationale for its selection of performance measures, how the ORYX data have been analyzed and used to improve performance, and the outcomes of these activities. WHAT DO CONTROL CHARTS DO? Control charts indicate whether an HCO's process is in statistical control (that is, stable insofar as only common cause variation exists) or out of statistical control (that is, unstable insofar as special cause variation exists). With the presence of special cause variation, the HCO should not make any change in its processes until the special cause is identified and eliminated. CHOOSING THE CORRECT CONTROL CHART: An HCO can use many different control charts. Selecting the correct control chart type for the type of data collected makes interpretation more sensitive for detecting special cause variation. The ORYX measures are calculated as proportions (rates), ratios, and means (continuous variables data, such as average length of stay), and this information forms the basis for selecting the correct type of control chart. In addition, the average rate (especially for rare event measures) and the average number of cases need to be considered when selecting the control chart type for small population measures.

Accidental Falls↗
PubMed1997

Automating and improving the data quality of a nursing department quality management program at a university hospital.

BACKGROUND: The development and implementation of a relational database program for nursing quality management at a university hospital was stimulated by a lack of consistent data management and analysis tools in the existing noncomputerized program. PROGRAM DEVELOPMENT AND IMPLEMENTATION: An initial software prototype implemented in the critical care service included data collection instruments for five areas: medication errors, patient falls, returns to an intensive care unit within 48 hours, hospital-acquired skin breakdown, and unplanned extubations. Access to the database was limited and paper reports only were disseminated on a scheduled basis. In a second phase, the database is being deployed throughout the nursing department using a local area network. Nurse managers will enter and interact with the quality database online and have access to graphics, reports, and action plan development. POSSIBLE ERRORS: A wide range of potential errors influences decisions on how to collect, store, retrieve, and process quality management data. Each type of error affects the nurse manager's ability to identify significant patterns or trends that are amenable to intervention. There is no right way of constructing and implementing a quality improvement database; only an optimum balance between cost, complexity, and efficacy. SUMMARY AND CONCLUSIONS: Initial feedback from end uses has been positive. A three-year experience with a personal computer database suggests that the personal computer-based information technology is appropriate for small to medium applications and can support departmentwide CQI efforts. A case scenario using simulated data is included to illustrate the use of computerized reports in assessing and taking action on an increase in falls.

Accidental Falls↗
PubMed1998

Intravenous immunoglobulin and the risk of hepatic veno-occlusive disease after bone marrow transplantation.

Recent reports using historical controls or registry cohorts suggest, respectively, either an increase in the mortality or a decrease in the incidence of hepatic veno-occlusive disease (VOD) with the administration of intravenous immunoglobulin (i.v.Ig) after bone marrow transplantation. These divergent results prompted us to conduct a retrospective analysis of two randomized clinical trials conducted at our center to determine the effect of i.v.Ig infusions on the development and severity of VOD. Patients were randomized to receive (n=318) or not to receive (n=315) i.v.Ig prophylaxis after human leukocyte antigen-identical sibling (n=414), mismatched or unrelated (n=178), or autologous or syngeneic (n=41) marrow transplantation. To determine the relationship of i.v.Ig to the development and severity of VOD, a single observer reviewed data displays created for each patient for grading VOD without knowledge of patient i.v.Ig use. In this analysis, VOD was defined as hyperbilirubinemia > or =2.0 mg/dL before day 20 and abrupt weight gain > or =2% before day 14 posttransplant in the absence of other causes of liver disease. Hepatic VOD developed in 235 (37%) of the 633 randomized patients. No evidence for VOD was found in 230 (36%) patients. The remaining 168 (27%) patients were classified as having liver disease of uncertain etiology. Hepatic VOD was judged to be severe in 63 (10%) and mild or moderate in 172 (27%) patients. The number of patients developing any VOD or severe VOD was similar between those randomized to i.v.Ig prophylaxis and untreated controls (115 vs. 120 and 32 vs. 31, respectively). Logistic regression models identified several covariates as significant (p < 0.01) factors associated with the development of severe VOD. Increased risk occurred with elevated pretransplant serum aspartate aminotransferase (odds ratio [OR] = 2.64) and earlier year of transplant (OR = 3.73); decreased risk occurred with autologous or twin donors (OR = 0.09) and acute myeloid leukemia (OR = 0.39). The development of any VOD was associated with an elevated pretransplant alkaline phosphatase (OR = 4.1), pretransplant use of vancomycin (OR = 1.6) or amphotericin (OR = 3.0), posttransplant use of cyclosporine (OR = 2.5), older patient age (OR = 1.03), and obesity (OR = 0.78). We concluded from the controlled trials of 633 patients that the administration of i.v.Ig did not influence the development or severity of VOD after bone marrow transplantation.

Bone Marrow Transplantation↗
PubMed2002

Visualization of significant ERD/ERS patterns in multichannel EEG and ECoG data.

OBJECTIVES: Analysis of event-related desynchronization (ERD) and event-related synchronization (ERS) often requires the investigation of diverse frequency bands. Such analysis can be difficult, especially when using multichannel data. Therefore, an effective method for the visualization of event-related changes in oscillatory brain activity is required. METHODS: A bootstrap-based method is presented which gives time-frequency maps showing only significant changes of ERD or ERS in predetermined frequency bands. RESULTS: Examples from an electroencephalographic study and an electrocorticographic study are shown. The results demonstrate how easily reactive channels and their spatio-temporal and frequency-specific characteristics can be identified by means of this method. CONCLUSIONS: The proposed method is a simple but effective way to visualize significant ERD/ERS patterns.

Algorithms↗
PubMed2005

Automation of a surface sampling probe/electrospray mass spectrometry system.

An image analysis automation concept and the associated software (HandsFree TLC/MS) were developed to control the surface sampling probe-to-surface distance during operation of a surface sampling electrospray system. This automation system enables both "hands-free" formation of the liquid microjunction used to sample material from the surface and hands-free reoptimization of the microjunction thickness during a surface scan to achieve a fully automated surface sampling system. The image analysis concept and the practical implementation of the monitoring and automated adjustment of the sampling probe-to-surface distance (i.e., liquid microjunction thickness) are presented. The added capabilities for the preexisting surface sampling electrospray system afforded through this software control are illustrated by an example of automated scanning of multiple development lanes on a reversed-phase C8 TLC plate and by imaging inked lettering on a paper surface. The post data acquisition processing and data display aspects of the software package are also discussed.

Chromatography, Thin Layer↗
PubMed2006

Automated sampling and imaging of analytes separated on thin-layer chromatography plates using desorption electrospray ionization mass spectrometry.

Modest modifications to the atmospheric sampling capillary of a commercial electrospray mass spectrometer and upgrades to an in-house-developed surface positioning control software package (HandsFree TLC/MS) were used to enable the automated sampling and imaging of analytes on and within large area surface substrates using desorption electrospray ionization mass spectrometry. Sampling and imaging of rhodamine dyes separated on TLC plates were used to illustrate some of the practical applications of this system. Examples are shown for user-defined spot sampling from separated bands on a TLC plate (one or multiple spots), scanning of a complete development lane (one or multiple lanes), or imaging of analyte bands in a development lane (i.e., multiple lane scans with close spacing). The post data acquisition processing and data display aspects of the software system are also discussed.

Chromatography, Thin Layer↗
PubMed2002

Structure and dynamics of a beta-helical antifreeze protein.

Antifreeze proteins (AFPs) protect many types of organisms from damage caused by freezing. They do this by binding to the ice surface, which causes inhibition of ice crystal growth. However, the molecular mechanism of ice binding leading to growth inhibition is not well understood. In this paper, we present the solution structure and backbone NMR relaxation data of the antifreeze protein from the yellow mealworm beetle Tenebrio molitor (TmAFP) to study the dynamics in the context of structure. The full (15)N relaxation analysis was completed at two magnetic field strengths, 500 and 600 MHz, as well as at two temperatures, 30 and 5 degrees C, to measure the dynamic changes that occur in the protein backbone at different temperatures. TmAFP is a small, highly disulfide-bonded, right-handed parallel beta-helix consisting of seven tandemly repeated 12-amino acid loops. The backbone relaxation data displays a periodic pattern, which reflects both the 12-amino acid structural repeat and the highly anisotropic nature of the protein. Analysis of the (15)N relaxation parameters shows that TmAFP is a well-defined, rigid structure, and the extracted parameters show that there is similar restricted internal mobility throughout the protein backbone at both temperatures studied. We conclude that the hydrophobic, rigid binding site may reduce the entropic penalty for the binding of the protein to ice. The beta-helical fold of the protein provides this rigidity, as it does not appear to be a consequence of cooling toward a physiologically relevant temperature.

Animals↗
PubMed2004

Studies of the enzymic mechanism of Candida tenuis xylose reductase (AKR 2B5): X-ray structure and catalytic reaction profile for the H113A mutant.

Xylose reductase from the yeast Candida tenuis (CtXR) is a family 2 member of the aldo-keto reductase (AKR) superfamily of proteins and enzymes. Active site His-113 is conserved among AKRs, but a unified mechanism of how it affects catalytic activity is outstanding. We have replaced His-113 by alanine using site-directed mutagenesis, determined a 2.2 A structure of H113A mutant bound to NADP(+), and compared catalytic reaction profiles of NADH-dependent reduction of different aldehydes catalyzed by the wild type and the mutant. Deuterium kinetic isotope effects (KIEs) on k(cat) and k(cat)/K(m xylose) show that, relative to the wild type, the hydride transfer rate constant (k(7) approximately 0.16 s(-1)) has decreased about 1000-fold in H113A whereas xylose binding was not strongly affected. No solvent isotope effect was seen on k(cat) and k(cat)/K(m xylose) for H113A, suggesting that proton transfer has not become rate-limiting as a result of the mutation. The pH profiles of log(k(cat)/K(m xylose)) for the wild type and H113A decreased above apparent pK(a) values of 8.85 and 7.63, respectively. The DeltapK(a) of -1.2 pH units likely reflects a proximally disruptive character of the mutation, affecting the position of Asp-50. A steady-state kinetic analysis for H113A-catalyzed reduction of a homologous series of meta-substituted benzaldehyde derivatives was carried out, and quantitative structure-reactivity correlations were used to factor the observed kinetic substituent effect on k(cat) and k(cat)/K(m aldehyde) into an electronic effect and bonding effects (which are lacking in the wild type). Using the Hammett sigma scale, electronic parameter coefficients (rho) of +0.64 (k(cat)) and +0.78 (k(cat)/K(m aldehyde)) were calculated and clearly differ from rho(k(cat)/K(aldehyde)) and rho(k(cat)) values of +1.67 and approximately 0.0, respectively, for the wild-type enzyme. Hydride transfer rate constants of H113A, calculated from kinetic parameters and KIE data, display a substituent dependence not seen in the corresponding wild-type enzyme rate constants. An enzymic mechanism is proposed in which His-113, through a hydrogen bond from Nepsilon2 to aldehyde O1, assists in catalysis by optimizing the C=O bond charge separation and orbital alignment in the ternary complex.

Alanine↗
PubMedDate not supplied

Traditional Chinese medicine database and application on the Web.

To study traditional Chinese medicines and exchange related information through the worldwide Web, we developed a traditional Chinese medicine database and a program for searching and displaying data in the database on the Web. In this paper, the traditional Chinese medicine database is briefly introduced; the methods used in developing the program, including ISAPI (Microsoft Internet Server Application Programming Interface), VRML (Virtual Reality Model Language), and JavaScript are described; and three application examples are also given.

Databases, Factual↗