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At least 1,243 records · Page 69Linked to original sources
PubMed2005

Comparison of the Bravo wireless and Digitrapper catheter-based pH monitoring systems for measuring esophageal acid exposure.

INTRODUCTION: We compared esophageal acid exposure data obtained during simultaneous esophageal pH studies using the Bravo wireless and the Slimline catheter-Mark III Digitrapper pH systems. METHODS: Twenty-five asymptomatic subjects underwent endoscopy with endoclip placement at the squamocolumnar junction (SCJ) and manometry to localize the lower esophageal sphincter (LES). A Bravo capsule was placed 6 cm above the SCJ and a Slimline catheter 5 cm above the LES. Relative positions were checked fluoroscopically. Synchronized pH data were compared by manual extraction into Excel spreadsheets. An in vivo pH reference was established with swallows of orange juice (pH 3.88). RESULTS: Median acid exposure time was greater with the Slimline compared to the Bravo system (Slimline, 3.4%; Bravo, 1.76%, p < 0.05) but electrode positions were similar. The dominant source of discrepancy between systems was an offset in recorded pH values around pH 4 as evidenced by the recorded values of the swallowed orange juice. Bench-top testing suggested that this offset was mainly attributable to the software designed to compensate for the difference in electrode recording characteristics between room and body temperature. After adjusting the pH data sets to accurately reflect actual orange juice pH, acid exposure between systems was similar (Slimline, 0.90%; Bravo, 1.15%). CONCLUSION: The Slimline system on average over-recorded esophageal acid exposure compared to the Bravo system largely because of a flawed software scheme for electrode thermal calibration. Accuracy of pH data sets from both systems can be improved by scrutiny for artifacts and use of an in vivo pH reference.

Acids↗
PubMed1998

[The place of radiosurgery in the treatment of hypophyseal adenoma].

Since 1984, the neurosurgical team of Sainte-Anne Hospital in Paris has taken in charge almost 750 patients for linear accelerator radiosurgery. But only a small percentage of them were harbouring a pituitary tumor. That is why the present paper is based mostly on literature data. Pituitary adenoma radiosurgery (RS) is a second intention therapeutic method. It should be recommended only after failure of medical and/or surgical treatment. Two main methods can be used: linear accelerator-radiosurgery and Cobalt-60 gamma unit. Both procedures provide equivalent results in terms of dosimetry, accuracy and clinical data. Results of various series presented in recent and updated literature have been studied and analysed. They show and confirm the efficiency of radiosurgery on tumor and hormone secretion controls, with few cases of pituitary insufficiency. However, results were disappointing concerning visual disorders, particularly if visual dysfunction and impairment existed before radiosurgery. All authors agree nowadays on different points: a) indications: invasive adenomas, with an incomplete resection, or adenomatous recurrences, b) contraindications: tumoral size > 20 mm, distance to visual pathways < 5 mm, c) imperative precautionary measures: less than 8 Gray must be delivered on visual pathways, less than 40 Gray on oculomotor nerves. In some cases, stereotactic fractioned radiotherapy may be an alternative treatment for large tumors close to visual pathways.

Adenoma↗
PubMed1999

Influence of internal dynamics on accuracy of protein NMR structures: derivation of realistic model distance data from a long molecular dynamics trajectory.

In order to study the effect of internal dynamics on the accuracy of NMR structures in detail, we generated NOE distance data from a long molecular dynamics trajectory of BPTI. Cross-relaxation rates were calculated from the trajectory by analysis of the appropriate proton-proton vector autocorrelation functions. A criterion for the convergence of correlation functions was developed, and the analysis was restricted to those correlation functions that had converged within the simulation time. Effective distances were determined from the calculated cross-relaxation rates. Internal dynamics affected the derived distances in a realistic way, since they were subject both to radial averaging (which increases the cross-relaxation rate) and angular averaging (which decreases the cross-relaxation rate). The comparison of the effective distances with average distance between the protons during the trajectory showed that for most the effects of angular and distance averaging essentially cancel out. For these distances, the effective distance derived from an NOE is therefore a very good estimate of the average distance, or the distance in the average structure. However, for about 10% of the distances, the effective distance was more than 10% larger than the average distance, while for about 5%, it was more than 10% smaller, in some cases by more than 2 A. Little correlation is observed between the effects on cross-relaxation rates to different protons of the same residue. The results of this analysis have implications for the way structures are calculated from NOE distance data. For many distances, the assumption of a rigid structure is valid, and large error bounds would result in the loss of too much information content. On the other hand, the error bounds very often employed are not wide enough for some of the effects seen in our study.

Animals↗
PubMed2000

Models for estimation of the (10)B concentration after BPA-fructose complex infusion in patients during epithermal neutron irradiation in BNCT.

PURPOSE: To create simple and reliable models for clinical practice for estimating the blood (10)B time-concentration curve after p-boronophenylalanine fructose complex (BPA-F) infusion in patients during neutron irradiation in boron neutron capture therapy (BNCT). METHODS AND MATERIALS: BPA-F (290 mg BPA/kg body weight) was infused i.v. during two hours to 10 glioblastoma multiforme patients. Blood samples were collected during and after the infusion. Compartmental models and bi-exponential function fit were constructed based on the (10)B blood time-concentration curve. The constructed models were tested with data from six additional patients who received various amounts of infused BPA-F and data from one patient who received a one-hour infusion of 170 mg BPA/kg body weight. RESULTS: The resulting open two-compartment model and bi-exponential function estimate the clearance of (10)B after 290 mg BPA/kg body weight infusion from the blood with satisfactory accuracy during the first irradiation field (1 ppm, i.e., 7%). The accuracy of the two models in predicting the clearance of (10)B during the second irradiation field are for two-compartment model 1.0 ppm (8%) and 0.2 ppm (2%) for bi-exponential function. The models predict the average blood (10)B concentration with an increasing accuracy as more data points are available during the treatment. CONCLUSION: By combining the two models, a robust and practical modeling tool is created for the estimation of the (10)B concentration in blood after BPA-F infusion.

Boron↗
PubMed2001

Food composition issues--implications for the development of food-based dietary guidelines.

Sound food composition databases that are both comprehensive and representative of available foods are an essential basic tool to develop Food Based Dietary Guidelines (FBDG). The main drawbacks of current food composition databases available in the European Union are: partial coverage of foods and nutrients, variability of analytical data, lack of accuracy in the description of food items, need for harmonisation of the expression of nutrients. An inappropriate use of these databases could lead to gross errors in the assessment of the nutrient intake levels, in the identification of the major sources of a nutrient, in the comparison of data between countries and in the analysis of time trends. Inadequacy of food composition data is, in part, responsible for the failure to understand some relationships between nutrient intakes and health or disease and for difficulties in establishing quantitative dietary guidelines in terms of nutrients. Recommendations are made for the compilation of future food composition databases and tools are proposed to enhance the quality of existing data. A careful study of the food composition databases is always necessary before nutrition recommendations are given and before trends in nutrient intakes are interpreted.

Data Interpretation, Statistical↗
PubMed2002

Predicting pesticide concentrations in river water with a hydrologically calibrated basin-scale runoff model.

Hydrological diffuse pollution models require calibration before they can be used to make accurate long-term predictions for a range of hydrological and meteorological conditions. As such, the applicability of the models to the dispersion of new pesticides is limited due to the lack of calibration data. In this study, the performance of a GIS-based basin-scale runoff model for predicting the concentrations of paddy-farming pesticides in river water was examined when calibrated using hydrological data alone, without optimization based on empirical pesticide concentration data. The prediction accuracy on a daily or hourly scale was somewhat unsatisfactory due to inevitable compromises concerning rice farming schedules. However, the month-averaged pesticide concentrations were satisfactorily accurate; more than 50% of predicted values were between half and twice the observed values, considering the deficiencies of the input data, particularly for pesticide usage, which may include up to 50% error.

Calibration↗
PubMedDate not supplied

Performance of a proposed determinative method for p-TSA in rainbow trout fillet tissue and bridging the proposed method with a method for total chloramine-T residues in rainbow trout fillet tissue.

Chloramine-T is an effective drug for controlling fish mortality caused by bacterial gill disease. As part of the data required for approval of chloramine-T use in aquaculture, depletion of the chloramine-T marker residue (para-toluenesulfonamide; p-TSA) from edible fillet tissue of fish must be characterized. Declaration of p-TSA as the marker residue for chloramine-T in rainbow trout was based on total residue depletion studies using a method that used time consuming and cumbersome techniques. A simple and robust method recently developed is being proposed as a determinative method for p-TSA in fish fillet tissue. The proposed determinative method was evaluated by comparing accuracy and precision data with U.S. Food and Drug Administration criteria and by bridging the method to the former method for chloramine-T residues. The method accuracy and precision fulfilled the criteria for determinative methods; accuracy was 92.6, 93.4, and 94.6% with samples fortified at 0.5X, 1X, and 2X the expected 1000 ng/g tolerance limit for p-TSA, respectively. Method precision with tissue containing incurred p-TSA at a nominal concentration of 1000 ng/g ranged from 0.80 to 8.4%. The proposed determinative method was successfully bridged with the former method. The concentrations of p-TSA developed with the proposed method were not statistically different at p < 0.05 from p-TSA concentrations developed with the former method.

Animals↗
PubMed2003

Improvement of pre- and post-processing environments of the dynamic two-dimensional reservoir model CE-QUAL-W2 based on GIS.

An Environmental Information System (EIS) coupled with a Geographic Information System (GIS) and water quality models is developed to improve the pre- and post-data processing function of CE-QUAL-W2. Since the accuracy of the geometric data in terms of a diverse water body has a great effect on the water quality variables such as the velocity, kinetic reactions, the horizontal and vertical momentum, to prepare the bathymetry information has been considered a difficult issue for modellers who intend to use the model. For identifying Cross Section and Profile Information (CSPI), which precisely contains hydraulic features and geographical configuration of a waterway, the automated CSPI extraction program has been developed using Avenue Language of the PC Arc/view package. The program consists of three major steps: (1) getting the digital depth map of a waterway using GIS techniques; (2) creating a CSPI data set of segments in each branch using the program for CE-QUAL-W2 bathymetry input; (3) selecting the optimal set of bathymetry input by which the calculated water volume meets the observed volume of the water body. Through those approaches, it is clear that the model simulation results in terms of water quality as well as reservoir hydraulics rely upon the accuracy of bathymetry information.

Automation↗
PubMed1992

Determination of eukaryotic protein coding regions using neural networks and information theory.

Our previous work applied neural network techniques to the problem of discriminating open reading frame (ORF) sequences taken from introns versus exons. The method counted the codon frequencies in an ORF of a specified length, and then used this codon frequency representation of DNA fragments to train a neural net (essentially a Perceptron with a sigmoidal, or "soft step function", output) to perform this discrimination. After training, the network was then applied to a disjoint "predict" set of data to assess accuracy. The resulting accuracy in our previous work was 98.4%, exceeding accuracies reported in the literature at that time for other algorithms. Here, we report even higher accuracies stemming from calculations of mutual information (a correlation measure) of spatially separated codons in exons, and in introns. Significant mutual information exists in exons, but not in introns, between adjacent codons. This suggests that dicodon frequencies of adjacent codons are important for intron/exon discrimination. We report that accuracies obtained using a neural net trained on the frequency of dicodons is significantly higher at smaller fragment lengths than even our original results using codon frequencies, which were already higher than simple statistical methods that also used codon frequencies. We also report accuracies obtained from including codon and dicodon statistics in all six reading frames, i.e. the three frames on the original and complement strand. Inclusion of six-frame statistics increases the accuracy still further. We also compare these neural net results to a Bayesian statistical prediction method that assumes independent codon frequencies in each position. The performance of the Bayesian scheme is poorer than any of the neural based schemes, however many methods reported in the literature either explicitly, or implicitly, use this method. Specifically, Bayesian prediction schemes based on codon frequencies achieve 90.9% accuracy on 90 codon ORFs, while our best neural net scheme reaches 99.4% accuracy on 60 codon ORFs. "Accuracy" is defined as the average of the exon and intron sensitivities. Achievement of sufficiently high accuracies on short fragment lengths can be useful in providing a computational means of finding coding regions in unannotated DNA sequences such as those arising from the mega-base sequencing efforts of the Human Genome Project. We caution that the high accuracies reported here do not represent a complete solution to the problem of identifying exons in "raw" base sequences. The accuracies are considerably lower from exons of small length, although still higher than accuracies reported in the literature for other methods. Short exon lengths are not uncommon.(ABSTRACT TRUNCATED AT 400 WORDS)

Base Sequence↗
PubMed1989

Accuracy curves: an alternative graphical representation of probability data.

Receiver operating characteristic (ROC) curves have been frequently used to compare probability models applied to medical problems. Though the curves are a measure of the discriminatory power of a model, they do not reflect the model's accuracy. A supplementary accuracy curve is derived which will be coincident with the ROC curve if the model is reliable, will be above the ROC curve if the model's probabilities are too high or below if they are too low. A clinical example of this new graphical presentation is given.

Bayes Theorem↗
PubMed2006

Experience of endoscopic ultrasound in an Australian tertiary hospital.

BACKGROUND: There is minimal prospective data on endoscopic ultrasound (EUS) experience in Australia. This study aimed to review the recent EUS experience of a single Australian tertiary hospital. METHODS: Data of all EUS carried out at St Vincent's Hospital, Melbourne, Australia were prospectively collected from August 2002 to September 2005. Patient demographics, indications, anatomical sites of EUS and fine-needle aspiration (FNA) were extracted from the database. A subset of 231 patients were involved in a prospective study to assess the clinical effect of EUS: with accuracy and outcomes data derived from surgical histology and pre-EUS and post-EUS questionnaires. RESULTS: Five hundred and sixty-one procedures were carried out for 526 patients. Men comprised 57% (n = 300). Mean age was 60 years (range, 19-92 years). The indications were (i) oesophageal 30.7% (n = 172); (ii) pancreaticobiliary 29.6% (n = 166); (iii) mediastinal and lung 20.7% (n = 116); (iv) gastric 15.9% (n = 89); and (v) duodenal 3.2% (n = 18). Endoscopic ultrasound-guided FNA was carried out in 30.3% procedures (170/561). Overall EUS accuracy was 84% (55/67 patients) and EUS-guided FNA accuracy was 88% (28/32 patients). There were no major complications. CONCLUSIONS: This is the largest reported Australian experience of EUS to date. Overall EUS was accurate, safe with no major complications or mortality and had useful outcomes. The role, expertise and accessibility of EUS in the Australian clinical setting are anticipated to continue to increase.

Adult↗
PubMedDate not supplied

Computer interface and software analysis for multi-channel, on-line temperature recording to any micro-computer.

A simple, inexpensive computer interface designed for in vitro or in vivo researchers with limited electronic experience allows direct on-line multi-channel temperature recording from thermistor probes to any micro-computer. The designed system saves time and increases the accuracy of collected data that are ready for storage in files compatible with graphic and statistical software. In vitro testing of the designed interface, over a range of 25-45 degrees C, showed a 0.999 intraclass correlation to reference water bath temperatures. In vivo testing using anesthetized rats involved simultaneous measurements of: (1) a thermogenic tissue, interscapular brown adipose temperature (IBAT), (2) core (colonic) temperature, and (3) surface (tail) temperature, a heat loss tissue. The temperatures measured by the designed computer-interface demonstrate excellent stability, sensitivity and accuracy when compared to respective temperatures measured by a YSI telethermometer.

Animals↗
PubMed2025

HighDimMixedModels.jl: Robust high-dimensional mixed-effects models across omics data.

High-dimensional mixed-effects models are an increasingly important form of regression in which the number of covariates rivals or exceeds the number of samples, which are collected in groups or clusters. The penalized likelihood approach to fitting these models relies on a coordinate descent algorithm that lacks guarantees of convergence to a global optimum. Here, we empirically study the behavior of this algorithm on simulated and real examples of three types of data that are common in modern biology: transcriptome, genome-wide association, and microbiome data. Our simulations provide new insights into the algorithm's behavior in these settings, and, comparing the performance of two popular penalties, we demonstrate that the smoothly clipped absolute deviation (SCAD) penalty consistently outperforms the least absolute shrinkage and selection operator (LASSO) penalty in terms of both variable selection and estimation accuracy across omics data. To empower researchers in biology and other fields to fit models with the SCAD penalty, we implement the algorithm in a Julia package, HighDimMixedModels.jl.

Algorithms↗
PubMed2004

Outpatient hysteroscopy and ultrasonography in the management of endometrial disease.

PURPOSE OF REVIEW: This review is to inform the ongoing debate about the choice between ultrasound and hysteroscopy in the management of endometrial disease presenting with abnormal uterine bleeding using information provided from recently published literature. RECENT FINDINGS: Transvaginal ultrasound measurement of endometrial thickness, using 4 or 5 mm cut-offs to define abnormality, is a good test for excluding endometrial cancer in women with postmenopausal bleeding. In contrast, hysteroscopy is a good test for detecting endometrial cancer, but less effective at excluding serious disease. The accuracy of transvaginal ultrasound in diagnosing intracavity pathology such as submucous fibroids and polyps is improved with saline instillation to levels of accuracy comparable to that of outpatient hysteroscopy. Miniaturization of hysteroscopes and ancillary instrumentation (e.g. development of bipolar intrauterine systems) has facilitated 'see and treat' outpatient hysteroscopy, so that it should no longer be considered simply an outpatient diagnostic modality. Preliminary cost-effectiveness studies have supported the use of ultrasound in the diagnosis of endometrial disease, but further, more comprehensive studies are required comparing ultrasound and outpatient hysteroscopy. SUMMARY: Recently published research has provided the clinician with high-quality data regarding the accuracy of ultrasound and hysteroscopy in the diagnosis of endometrial disease. Despite this, controversy remains regarding the relative roles of these uterine imaging modalities. Future research needs to be directed towards providing effectiveness and cost-effectiveness data in order to resolve the ongoing debate and guide best clinical practice.

Endometrial Hyperplasia↗
PubMed2003

A comparison of three methods for estimating height in the acutely ill elderly population.

BACKGROUND: Most estimates of nutritional status rely on accurate recording of not only body weight but also height. Standing height is difficult to measure accurately in older adults due to mobility problems and kyphosis. Surrogate methods have been developed to estimate height including arm-span, demi-span and knee height. There are currently little data on the accuracy of these methods in the sick elderly population or which method is the most suitable in the clinical situation. OBJECTIVE: To compare three commonly used clinical measurements that can estimate height and analyse their agreement with current height. Also to evaluate which method can be used most frequently. METHODS: We used data collected as part of a larger intervention trial, in which elderly in-patients (over 65 years), were measured for demi-span, half arm-span, knee height and standing height. RESULTS: The results showed that demi-span and half arm-span could be measured in the largest proportions of our population, 75.6 and 72.3%, respectively. The correlation coefficients were high for all three estimates of height, r = 0.86 for demi-span, r = 0.87 for arm-span, and r = 0.89 for knee height (P < 0.0001 for all three). However, agreement analysis demonstrated very poor agreement between standing height and all the methods of estimation. The mean differences were 4.33 cm for demi-span, 7.04 cm for arm-span and -0.6 cm for knee height.

Acute Disease↗
PubMed1986

[Results and problems of a questionnaire study on the incidence of some selected bronchopulmonary diseases in 3,302 students beginning school in the city of Frankfurt/Main].

During the last years between air pollution and respiratory illness has been suggested increasingly often. There are no exact data about prevalence and longitudinal development of bronchopulmonary diseases. This study will propose a method to get these data by questionnaire. Although a relatively simple questionnaire was selected it was soon apparent that the answers of German parents differed substantially from those of parents of other nationalities. It was felt that this difference could be due to anxiety or misunderstanding on part of the parents, so in the interest of accuracy only the data concerning the German children were analysed. Analysis of 2,214 questionnaires revealed the following tendencies in the 5 to 6 year old age group: infectious diseases 30.4%, asthma 1.4% croup syndrome 4.5%, recurrent croup 4.1%. There is a very high percentage of pupils suffering from recurrent croup because this kind of croup most probably is associated with air pollution. We believe that the extension of data collection in this age group is practicable and would produce useful data to establish a correlation between air pollution and bronchopulmonary diseases.

Asthma↗
PubMed2006

Conception and development of a bibliographic database of blood nutrient fluxes across organs and tissues in ruminants: data gathering and management prior to meta-analysis.

In the organism, nutrient exchanges among tissues and organs are subject to numerous sources of physiological or nutritional variation, and the contribution of individual factors needs to be quantified before establishing general response laws. To achieve this, meta-analysis of data from publications is a useful tool. The objective of this work was to develop a bibliographic database of nutrient fluxes across organs and tissues of ruminant animals (Flora) under Access using the Merise method. The most important criteria for Flora were the ease to relate the various information, the exhaustivity and the accuracy of the data input, a complete description of the diets, taking into account the methods of the methodological procedures of measurement and analysis of blood nutrients and the traceability of the information. The conceptual data model was built in 6 parts. The first part describes the authors and source of publication, and the person in charge of data input. It clearly separates and identifies the experiments, the groups of animals and the treatments within a publication. The second part is concerned with feeds, diets and their chemical composition and nutritional value. The third and fourth parts describe the infusion of any substrates and the methods employed, respectively. The fifth part is devoted to the results of blood flows and nutrient fluxes. The sixth part gathers miscellaneous experimental information. All these parts are inter-connected. To model this database, the Merise method was utilised and 26 entities and 32 relationships were created. At the physical level, 93 tables were created, corresponding, for the majority, to entities and relationships of the data model. They were divided into reference tables (n = 65) and data tables (n = 28). Data processing was developed in Flora and included the control of the data, generic calculations of unknown data from given data, the automation of the estimation of the missing data or the chemical composition of the diets. It also included the construction of tables for meta-analyses and the study of the variations of several factors within publications (pre-coding of meta-analyses). Overall, the system was built to facilitate the gathering, input, validation, management and retrieval of data from publications.

Animal Feed↗