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At least 523 records · Page 29Linked to original sources
PubMed2002

Caffeine in apnoeic Asian neonates: a sparse data analysis.

AIMS: To monitor plasma caffeine concentrations and adverse effects and to study the pharmacokinetics of caffeine in neonatal apnoea in the local Asian population after intravenous administration of caffeine. METHODS: Eighteen neonates with apnoea were treated with caffeine citrate at a loading dose of 10 mg caffeine base kg-1 and a maintenance dose of 2.5 mg kg-1 day-1. Blood samples, three after loading and two after the maintenance dose on day 2, 3, 7, 14 and 21 were taken and analysed for caffeine and its main metabolites using solid phase extraction and h.p.l.c. Adverse effects were monitored. Sparse data pharmacokinetic analysis was performed using P-Pharm. RESULTS: Mean caffeine concentrations varied from 10 to 20 mg l-1 throughout treatment (range 3.6-28.4 mg l-1). These concentrations were efficacious; less so in those with lower concentrations. Adverse effects included gastrointestinal disturbances, diuresis and hyperglycaemia. Pharmacokinetic parameter estimates [mean (coefficient of variation%)] were CL=0.00628 (17.5%) l h-1 and V=0.961 (20.3%) l. CL (l h-1)=0.004248 * wt(kg)+0.00154; r=0.8, P<0.01, explained 64% of the variation. V (l)=0.6299 * wt(kg)+0.259; r=0.67, P<0.01, explained 45% of variation. Model-predicted compared with observed plasma concentrations in a separate group of 10 neonates were unbiased and of good precision. CONCLUSIONS: The dosing regimen studied was suitable for our local Asian neonates as it resulted in therapeutic caffeine concentrations for adequate treatment of apnoea. Adverse effects were tolerable. Therefore, to avoid a higher incidence of adverse effects, this regimen should be retained and not increased as proposed by other workers. CL and V were within values of those reported for neonatal apnoea. Sparse data analysis showed that weight alone was adequate as the influential variable for the accurate prediction of individual pharmacokinetic parameters, plasma concentrations and for dosage adjustment if required.

Apnea↗
PubMed1994

Effect of prednisone and hydroxychloroquine on coronary artery disease risk factors in systemic lupus erythematosus: a longitudinal data analysis.

PURPOSE: To determine the effect of prednisone dose and hydroxychloroquine dose on the coronary artery disease risk factors serum cholesterol level, mean arterial blood pressure, and weight in patients with systemic lupus erythematosus. PATIENTS AND METHODS: A longitudinal cohort study of 264 patients with systemic lupus erythematosus was conducted. For all patients in the cohort, serum cholesterol, mean arterial pressure, weight, prednisone dose, hydroxychloroquine dose, and other potential confounding variables were recorded at each visit. Regression analysis appropriate for longitudinal data was used to assess the effect of prednisone on serum cholesterol and mean arterial pressure. To assess the effect of prednisone on weight, patients' weights were compared 90 days before and after a 10-mg or 20-mg increase in prednisone. RESULTS: A total of 3,027 patient visits were analyzed. In the regression model for serum cholesterol, a change in prednisone dose of 10 mg was associated with a change in cholesterol of 7.5 +/- 1.46 (SE) mg% after adjustment for the other significant variables in the model, including sex, race, hydroxychloroquine dose, and proteinuria. In the regression model for hydroxychloroquine, the 200-mg and the 400-mg dose were both associated with lower serum cholesterol (8.9 +/- 3.44 SE mg%). In the regression model for mean arterial blood pressure, a 10-mg change in prednisone dose led to a change in mean arterial blood pressure of 1.1 mm Hg after adjustment for age, weight, and antihypertensive drug use. A 10-mg increase in prednisone dose was associated with a mean weight change of 5.50 +/- 1.23 (SE) lb. CONCLUSIONS: Changes in prednisone dose led to definable changes in risk factors for coronary artery disease, even after adjustment for other variables known to affect these risk factors. According to longitudinal regression analysis, hydroxychloroquine therapy was associated with lower serum cholesterol.

Adult↗
PubMed2003

Pooled-data analysis of three randomized, double-masked, six-month studies comparing intraocular pressure-reducing effects of latanoprost and timolol in patients with ocular hypertension.

PURPOSE: To assess retrospectively the intraocular pressure (IOP)-reducing effect of latanoprost compared with timolol in the subset of patients with ocular hypertension (OH). METHODS: Three randomized, double-masked, multicenter, parallel group, 6-month studies conducted in the United States, United Kingdom, and Scandinavia compared the efficacy and safety of latanoprost and timolol. The present study represents an analysis of the pooled data for the subset of OH patients. Intent-to-treat analyses were based on all randomized OH patients. RESULTS: Of the 441 patients with OH, 247 were treated with latanoprost and 194 were treated with timolol. Baseline mean diurnal IOP levels were 24.4 +/- 0.2 mm Hg (mean +/- standard error of the mean) in the latanoprost group and 24.2 +/- 0.2 mm Hg in the timolol group. Overall, latanoprost lowered mean diurnal IOP by 1.1 +/- 0.2 mm Hg (95% CI: 1.6 to 0.7 mm Hg, P < 0.001) more than timolol. The difference in IOP-lowering ability between the two drugs was not shown to be related to patient sex, age, race, presence or absence of previous treatment of OH, time elapsed since ocular diagnosis, or family history of glaucoma/OH. Percentage reductions from baseline in diurnal IOP levels of at least 20% were achieved by 83% of patients treated with latanoprost versus 62% of those receiving timolol. CONCLUSION: Latanoprost provides superior IOP reduction compared with timolol in patients with OH.

Antihypertensive Agents↗
PubMed1987

On multiparameter data analysis in flow cytometry.

Increasing numbers of parameters that are accessible to simultaneous measurement in flow cytometric instruments, combined with the extremely large sample sizes common in flow cytometry, make it necessary to examine methods of multivariate statistics for their applicability to problems of visualization and quantitative analysis of flow cytometric data. This article describes some approaches to dimensionality reduction that appear well suited for data sets obtained by flow cytometry.

Flow Cytometry↗
PubMed2005

In vivo intravascular ultrasound-derived thin-cap fibroatheroma detection using ultrasound radiofrequency data analysis.

OBJECTIVES: The purpose of this study was to assess the prevalence of intravascular ultrasound (IVUS)-derived thin-cap fibroatheroma (IDTCFA) and its relationship with the clinical presentation using spectral analysis of IVUS radiofrequency data (IVUS-Virtual Histology [IVUS-VH]). BACKGROUND: Thin-cap fibroatheroma lesions are the most prevalent substrate of plaque rupture. METHODS: In 55 patients, a non-culprit, non-obstructive (<50%) lesion was investigated with IVUS-VH. We classified IDTCFA lesions as focal, necrotic core-rich (> or =10% of the cross-sectional area) plaques being in contact with the lumen; IDTCFA definition required a percent atheroma volume (PAV) > or =40%. RESULTS: Acute coronary syndrome (ACS) (n = 23) patients presented a significantly higher prevalence of IDTCFA than stable (n = 32) patients (3.0 [interquartile range (IQR) 0.0 to 5.0] vs. 1.0 [IQR 0.0 to 2.8], p = 0.018). No relation was found between patient's characteristics such as gender (p = 0.917), diabetes (p = 0.217), smoking (p = 0.904), hypercholesterolemia (p = 0.663), hypertension (p = 0.251), or family history of coronary heart disease (p = 0.136) and the presence of IDTCFA. A clear clustering pattern was seen along the coronaries, with 35 (35.4%), 31 (31.3%), 19 (19.2%), and 14 (14.1%) IDTCFAs in the first 10 mm, 11 to 20 mm, 21 to 30 mm, and > or =31 mm segments, respectively, p = 0.008. Finally, we compared the severity (mean PAV 56.9 +/- 7.4 vs. 54.8 +/- 6.0, p = 0.343) and the composition (mean percent necrotic core 19.7 +/- 4.1 vs. 18.1 +/- 3.0, p = 0.205) of IDTCFAs between stable and ACS patients, and no significant differences were found. CONCLUSIONS: In this in vivo study, IVUS-VH identified IDTCFA as a more prevalent finding in ACS than in stable angina patients.

Aged↗
PubMed2005

Field data analysis and application of a complex water column biogeochemical model in different areas of a semi-enclosed basin: towards the development of an ecosystem management tool.

The Pagasitikos gulf ecosystem is studied through the analysis of experimental field data acquired during several monitoring projects and the application of a complex biogeochemical model. The gulf was separated into three different parts (internal, top central-external, bottom central-external) according to the patterns exhibited by the key ecosystem indicators. Unlike other semi-enclosed gulfs Pagasitikos can be characterised as meso-oligotrophic undergoing periods of P or N limitation. Although the signal of nutrient inputs is not very clear in the field data, their importance is assessed through simulation. Increased phosphate concentrations either due to mixing or due to anthropogenic activities can result in phytoplanktonic blooms with significant contribution by diatoms. The effect of hydrodynamic patterns on primary production has been demonstrated through ecosystem modeling indicating that due to long stratification periods, all nutrients released through the benthic regeneration are trapped in the deeper layers, developing a microbial food web. However when the thermocline erodes nutrients find their way up in the upper layers of the euphotic zone and the system turns into more classical type with primary producers growing significantly faster.

Animals↗
PubMed2004

Exploratory EEG data analysis for psychophysiological experiments.

A method for the exploratory analysis of electroencephalographic (EEG) data for neurophysiological experiments is presented. It is based on a time-frequency decomposition of the EEG time series, which is measured by several electrodes in the scalp surface, and includes the computation of a statistic that measures the deviations of the log-power with respect to the pre-stimulus average; the computation of a significance index for these deviations; a new type of display (the time-frequency-topography plot) for the visualization of these indices, and the segmentation of the time-frequency plane into regions with uniform activation patterns. As a particular example, an experiment to study EEG changes during figure and word categorization is analyzed in detail.

Algorithms↗
PubMed2002

Semiautomated data analysis of flow cytometric estimation of fetomaternal hemorrhage in D- women.

BACKGROUND: Accurate and reliable measurement of the volume of fetal D+ cells in D- women is required for adequate anti-D prophylaxis. A semiautomated flow cytometry assay based on a standardized calibration curve that was created with simulated fetomatemal hemorrhage (FMH) mixtures was developed. STUDY DESIGN AND METHODS: A calibration range of 0.083- to 2-percent D+ cells in the D-RBC mixtures (2-44 mL calculated FMH) was analyzed by use of a flow cytometer (XL-MCL, Coulter Electronics Ltd). Linear regression analysis of the calibration curve data with computer software (Excel, Microsoft) allowed semiautomated determination of the FMH volume. To optimize the assay, fresh versus frozen and thawed RBCs, RBCs from adults who are heterozygous for D or cord RBCs, and indirect- or direct-labeling techniques were evaluated by use of MoAbs. RESULTS: Fresh RBCs from adults heterozygous for D were chosen for routine use, although equivalent calibration curves were obtained with all cells tested (n = 12 calibration assays; r2 = 0.999; mean SD, 14%). A monoclonal anti-D reagent (Therad 10, Diagnostics Scotland) worked well in both indirect-(anti-IgG F(ab)-FITC) and direct-(anti-D-FITC) labeling methods compared to the use of BRAD-3 FITC. In routine practice, the FMH volumes obtained were mainly lower than those obtained in the Kleihauer Betke test when there was less than 4 mL of FMH. CONCLUSION: Semiautomated data acquisition and calibration curve analysis represents a further step toward standardization of flow cytometry for accurate FMH quantification and facilitates evaluation and control of day-to-day variations between laboratories, flow cytometers, and operators.

Antibodies, Monoclonal↗
PubMed2005

Comparative bioavailability of two formulations of levofloxacin and effect of sex on bioequivalence analysis. Data from a randomised, 2 x 2 crossover trial in healthy volunteers.

Bioequivalence of levofloxacin (CAS 100986-85-4) 500 mg tablets was assessed in a single dose, open, randomised, crossover trial, with a minimum washout period of 7 days. Serum samples were obtained over 36 h (at baseline, 0.250, 0.500, 0.750, 1.00, 1.25, 1.50, 1.75, 2.00, 2.33, 2.67, 3.00, 4.00, 6.00, 8.00, 12.0, 16.0, 24.0, and 36.0 h post-dose). Levofloxacin serum concentration levels were determined by high-pressure liquid chromatography with fluorescence detection (LOQ 98.31 ng/mL). The 90% confidence intervals (90% Cls; obtained by ANOVA using In-transformed data) for overall bioequivalence analysis were 99.09-115.26% for Cmax, 99.41-105.60% for AUClast and 98.68-104.93% for AUCinf, that is, all within the predefined ranges. Within-gender analysis also produced 90% CIs within the predefined ranges. The use of gender-related model effects showed that sex was a significant factor for AUClast and AUCinf, however, when parameters were normalised by body weight adjusted dose, none of the tested model effects were significant. Comparison between male and female body weight showed significant differences. It may be therefore concluded that the evaluated formulations are bioequivalent in terms of rate and extent of absorption and that possible differences between male and female pharmacokinetic parameters may be related to differences in body weight.

Adult↗
PubMed2005

Methodological considerations and approach to cross-technique comparisons using in vivo coronary plaque characterization based on intravascular ultrasound radiofrequency data analysis: insights from the Integrated Biomarker and Imaging Study (IBIS).

Grey scale intravascular ultrasound (IVUS) is a valuable clinical tool to assess the extent and severity of coronary atheroma. However, it cannot reliably identify plaques with a high-risk of future clinical events. Serial IVUS studies to assess the progression and/or regression of atherosclerotic plaques demonstrated only modest effects, of pharmacological intervention on plaque burden, even when clinical efficacy is documented. Spectral analysis of radiofrequency ultrasound data (IVUS-virtual histology (IVUS-VH), Volcano Therapeutics, Rancho Cordova, CA) has the potential to characterize accurately plaque composition. The Integrated Biomarker and Imaging Study (IBIS) evaluated both invasive and non-invasive imaging techniques along with the assessment of novel biomarkers to characterize sub-clinical atherosclerosis. IVUS-VH was not included at the start of the IBIS protocol. The purpose of this paper is to describe the methodology we used to obtain and analyse IVUS-VH images and the approach to cross-correlations with the other techniques.

Biomarkers↗
PubMed2026

Vancomycin Effectiveness in Reducing Surgical Site Infection in Posterior Spinal Fusion Surgery: A Retrospective Data Analysis of the STRIVE Trial.

STUDY DESIGN: Retrospective analysis of prospectively collected data. OBJECTIVE: To re-evaluate vancomycin as a preventive measure for surgical site infection (SSI). SUMMARY OF BACKGROUND DATA: Intrawound vancomycin powder is used to prevent SSIs in spinal surgery. Prior studies, often limited to single institutions or small samples, have shown mixed efficacy and potential increases in non- S. aureus and Gram-negative infections. We hypothesized that SSIs rates would be similar with and without intrawound vancomycin in posterior spinal fusion (PSF) surgery. METHODS: Prospectively collected data from the 3595 patients in the STaphylococcus aureus suRgical Inpatient Vaccine Efficacy (STRIVE) trial were stratified by intrawound antibiotic usage. Multivariate logistic regression assessed the effect of vancomycin use on SSI, adjusting for patient demographics and SSI-associated risk factors. Secondary outcomes included critical care stay, reoperation, sepsis, and hospital readmission. RESULTS: Of 3311 patients who underwent surgery, 847 (26%) received only intrawound vancomycin and 1534 (46%) received no intrawound antibiotics. Sixty (8%) patients developed postoperative SSI, of whom 20 (33%) had received intrawound vancomycin. Receiving intrawound vancomycin was not associated with SSI incidence versus no intrawound antibiotics [odds ratio (OR): 0.77; 95% CI: 0.42-1.42], critical care stay (OR: 0.94; 95% CI: 0.78-1.12), or sepsis (OR: 2.04; 95% CI: 0.62-6.73). However, intrawound vancomycin was associated with increased odds of hospital readmission (OR: 1.82; 95% CI: 1.28-2.6; P < 0.001) and reoperation (OR: 1.75; 95% CI: 1.18-2.6; P = 0.005). Factors significantly associated with intrawound vancomycin use included intraoperative antibiotic readministration (OR: 2.97; 95% CI: 1.36-6.5; P =0.006) and hospital location, lower odds in Europe (OR: 0.13; 95% CI: 0.06-0.29; P < 0.001) or Asia (OR: 0.02; 95% CI: 0-0.08; P < 0.001) versus North America. CONCLUSIONS: Intraoperative vancomycin use was not associated with reduced SSI incidence compared with no intrawound antibiotics after PSF surgery. LEVEL OF EVIDENCE: Level II.

Humans↗
PubMed2001

Multiple diffraction data analysis for macromolecular crystals in stereoscopic multibeam imaging.

A detailed analysis of multiple diffraction data collected by the stereoscopic multibeam imaging technique from a tetragonal lysozyme crystal is reported. Calculations based on the dynamical theory are employed to account for diffraction profiles obtained with Bragg-angle scan in stereoscopic imaging and the conventional azimuthal scan in Renninger arrangement. The formation of a multibeam intensity profile and the relationship and mutual influence between the two scans are investigated. A simple practical method of quantitative estimation of the reflection phases of structure-factor multiplets from the experimental data obtained with two inversion-symmetry-related diffractions is proposed. The procedures for data handling and for distinguishing "partial" diffraction images from "full" diffraction images are also developed considering multibeam diffraction geometry and experimental conditions. These procedures thus provide a practical way of reconstructing diffraction profiles for experimental phase determination for macromolecular crystals.

Journal Article↗
PubMed2005

Current practices in cancer spatial data analysis: a call for guidance.

There has long been a recognition that place matters in health, from recognition of clusters of yellow fever and cholera in the 1800s to modern day analyses of regional and neighborhood effects on cancer patterns. Here we provide a summary of discussions about current practices in the spatial analysis of georeferenced cancer data by a panel of experts recently convened at the National Cancer Institute.

Journal Article↗
PubMed1991

Results of the central data analysis.

This chapter presents the results of blind serological studies carried out by workshop participants on 87 monoclonal antibodies (mAbs) supplied to them as a coded panel. Twenty six mAbs had been studied in the first workshop. Participants were asked to carry out immunohistochemical, immunocytological or flow cytometric analysis on a mandatory panel of target tissues or cells. Central computer analysis and other supporting data allowed the assignment of 33 mAbs to seven clusters. Two of the antigens identified have been cloned while two more have been defined as carbohydrate epitopes. The results allow comparison of new mAbs against lung cancer with existing ones and are beginning to provide a description of the antigenic structure of the SCLC cell surface.

Antibodies, Monoclonal↗
PubMed1986

Risk factors in mass screening for breast cancer, multivariate analysis of data from the Cuban diagnosis pilot study.

The evolution of mammography has provided possibilities for mass screening programs. Early diagnosis is considered the most important factor in reducing the breast cancer mortality but the mass screening is very expensive if we include all female population. In this paper we show the results of an early diagnosis pilot study with a multivariate data analysis. Data concerning risk factors (age, age at menarche, menopause, parity, age at first childbirth, lactation, abortions and previous benign breast disease) were recorded in 438 patients with breast carcinoma and 1750 patients with benign breast diseases diagnosed in the Early Diagnosis Pilot Program at the National Institute of Oncology and Radiobiology in Cuba. A group of 449 healthy women living in Havana City was also studied. Age and age at first childbirth were the major factor considered. Multivariate data analysis allowed to build stratification trees identifying subgroups with different breast cancer incidence. The usefulness of these stratifications for screening with optimal coverage, sufficiency and efficacy, is discussed.

Adult↗
PubMed1999

Some aspects of data analysis in dentistry.

In dentistry many studies collect hierarchical data, but this is not always recognised or understood by the researchers. This paper sets out to describe such studies and discusses aspects of their design, data collection and analysis. Sometimes these studies may be dealt with in a simple way, but others may require the help of a professional statistician to deal with analytical problems that are encountered.

Data Interpretation, Statistical↗