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At least 829 records · Page 46Linked to original sources
PubMed2001

A new and versatile method for determination of thiolamines of biological importance.

A method for the separation and quantitation of several important biological thiolamines is described. The procedure employs a C18 reversed-phase HPLC system to separate the dinitrophenyl derivatives of reduced and oxidized glutathione and cysteine and relies on an internal standard, Nepsilon-methyllysine, to minimize experimental error. The method was validated in three matrices (water, HepG2 cell lysates, and mouse liver homogenates) using several criteria. The detector response was linear for the dinitrophenyl derivatives of glutathione, glutathione disulfide, cysteine, and cystine in the concentrations ranging from 10 to 50 nmol/ml. Inter- and intra-day variation, percent recovery in the biological matrices, and limits of detection and quantitation were determined. For the most accurate determination, it is essential that standard curves be produced daily and in the same matrix as that being analyzed.

Amines↗
PubMed2002

Evidential value of injuries useful for reconstruction of the pedestrian-vehicle location at the moment of collision.

The paper presents final results of the studies concerning the usefulness of knee, ankle, hip, pelvis and neck injuries in reconstructing the circumstances of car-to-pedestrian accidents. Each type of injuries was evaluated with regard to possible reconstruction of the victim's position (upright or recumbent) at the moment of collision and in the upright hits-the side of the pedestrian's body hit. In each group, a chance of proper reconstruction of the pedestrian's location (which determined the frequency of injury pattern assumed as the typical one of a given position or impact side) and error risk (percentage of cases in which the injury pattern showed improper position or impact side) were calculated. These data were compared with similarly calculated possibilities of deducing based on the classical "bumper" injuries to soft tissues and "bending" fractures of the lower limb bone diaphyses. It was shown that the bone bruises within the knee epiphyses were very specific evidence for upright hits as they confirm the limb load by body mass at the moment of pathological dislocation of joint structures on impact. The evidential value of knee injuries was found to be similar to that of other "classical" methods based on bumper injuries or even higher in lateral and front hits. The injuries to the remaining structures were less frequently found and their correlation with the victim's position or impact side was lower. Nevertheless, once the whole complex of these injuries is taken into consideration the chances of proper reconstruction of the pedestrian-vehicle location increase and the risk of opinion error is minimized.

Accidents, Traffic↗
PubMed1997

CT angiography of intracranial aneurysms: advantages and pitfalls.

OBJECTIVE: To determine the clinical usefulness of computed tomography (CT) angiography in the evaluation of cerebral aneurysms. MATERIALS AND METHODS: From October 1994 through April 1996, 26 patients with 30 surgical proven intracranial aneurysms underwent both CT angiography and catheter cerebral angiography. The findings of the two methods were reviewed independently and then compared with each other. RESULTS: Comparing with catheter angiography, CT angiography was superior in demonstrating the aneurysmal neck in seven aneurysms but was inferior in one. The thrombosed part and calcification of aneurysms were clearly demonstrated on CT angiograms. CT angiography also aided in differentiating tight vascular loops from aneurysms. On CT angiograms, one posterior communicating arterial aneurysm was overlooked and another anterior choroidal artery aneurysm was misinterpreted as a posterior communicating artery aneurysm. Of note were two patients in whom the infundibulum of the orbitofrontal artery was misinterpreted as the anterior communicating artery aneurysm. CONCLUSION: CT angiography can compliment conventional catheter angiography for its better demonstration of the 3-dimensional anatomy. It can provide surgical information about the neck, calcification and thrombosed part of an aneurysm and its relation to adjacent structures. However, caution is advocated because CT angiography may fail to demonstrate small but important vessels such as posterior communicating, anterior choroidal and orbitofrontal arteries. Recognition of the limitations of CT angiography is important in minimizing interpretation errors.

Adult↗
PubMed2002

An equivalent length model of microdialysis sampling.

One of the critical issues in microdialysis sampling is how to predict the extraction fraction (E(d)), based on transport properties of analytes in both tissues and probes. A one-dimensional (1-D) model has been used widely in previous studies to predict E(d) at the steady state. However, this model is valid only for long probes. To this end, an equivalent length (EL) model was developed for probes with any length used in experiments. The key idea in the model was to replace the probe length (L) in the 1-D model with an equivalent length (L(E)) when calculating transport resistance in surrounding tissues. The length difference, (L(E)-L), was assumed to be proportional to the penetration depth of analytes (Gamma). The proportionality constant (lambda) was determined through minimizing the errors in predicted E(d). We found that, the EL model could accurately predict E(d) when lambda=0.369. The maximum error in EL model predictions was <6%, for model constants varying in the same ranges as those in microdialysis experiments. This error was one order of magnitude smaller than that in 1-D model predictions.

Algorithms↗
PubMed2002

Training costs and investment payback of implementing molecular diagnostics for identification of vancomycin resistant enterococci in a clinical microbiology laboratory.

Molecular diagnostics may be a more efficient method to manage resources; but most Microbiology laboratories have not introduced them into routine use due to the specialized training required. Using vancomycin resistant enterococci (VRE) screening during a comparison of a multiplex PCR (MPCR) and conventional biochemical testing (CBT) we studied 3 objectives: 1) to develop a molecular diagnostics in-house training program, 2) to assess the training program outcomes for competency and confidence, and 3) to determine laboratory payback. A training program for 14 technologists using multiple adult learning methods was implemented. Methods to minimize technical errors were introduced and included: use of a calibrated loop to deliver sample; prealiquotting reagents; increasing volume of specimen; addition of gel loading dye directly into reaction tubes; and establishment of an equivocal zone. In our laboratory MPCR costs $7.06 less than CBT, therefore the payback period for training and implementation would be approximately 3 years.

Cost-Benefit Analysis↗
PubMed1995

Correcting myopic astigmatism with an areal 193 nm excimer laser ablation.

A new system to correct symmetric bow-tie myopic astigmatism with the excimer laser using oval apertures for toric ablations is described. Initial results in two patients who had -5.0 and -5.5 diopters of astigmatism after surgery with six-months follow-up showed a reduction of up to 85% with a minimal axial error of two degrees.

Aged↗
PubMed1994

Improvements in estimating the harmonics-to-noise ratio of the voice.

An improved algorithm for computing harmonics-to-noise ratio (HNR) of the voice was developed and tested using synthesized vowels at various fundamental frequencies and known HNR values. The described algorithm implements a stringent routine for the identification of pitch pulse boundary markers based on a combination of peak-picking and zero-crossing procedures. Results showed mean absolute errors between computed versus expected HNR to be < 2 dB, a significant improvement over previously reported methods. Computational errors were minimized most effectively with vowel samples in the range of 17 to -10 dB HNR. Normative data for young adult males and females indicate that HNR < 13 dB may be considered abnormal in a majority of cases.

Adult↗
PubMed1998

Validation of an oscillometric electronic sphygmomanometer in an obstetric population.

Use of an automated electronic sphygmomanometer will allow us to minimize the errors inherent in mercury sphygmomanometry. We conducted this validation according to the 1990 protocol of the British Hypertensive Society. We recruited 87 subjects from the antenatal population of Kandang Kerbau Hospital and took three sequential readings using simultaneously both manual and electronic sphygmomanometry. A total of 261 readings from either method were thus collected and the results analyzed to compare the accuracy of electronically read blood pressure with that assessed manually. We found that 89.9% of the electronically read pressures differed from the manually read pressures by 5 mm Hg or less and 98.9% of the electronic readings differed from manual readings by 10 mm Hg or less; only 0.4% of readings had a difference of more than 15 mm Hg. The accuracy of the device was not affected either by the blood pressure or the arm circumference.

Adult↗
PubMed2002

Model-based interpretation of cardiac beats by evolutionary algorithms: signal and model interaction.

This paper presents a new approach for cardiac beat interpretation, based on a direct integration between a model and observed ECG signals. Physiological knowledge is represented by means of a semi-quantitative model of the cardiac electrical activity. The interpretation of cardiac beats is formalized as an optimization problem, by minimizing an error function defined between the model's output and the observations. Evolutionary algorithms (EAs) are used as the search technique in order to obtain the set of model parameters reproducing at best the observed phenomena. Examples of model adaptation to three different kinds of cardiac beats are presented. Preliminary results show the potentiality of this approach to reproduce and explain complex pathological disorders and to better localize their origin.

Algorithms↗
PubMed1999

Radial basis function neural networks for the characterization of heart rate variability dynamics.

This study introduces new neural network based methods for the assessment of the dynamics of the heart rate variability (HRV) signal. The heart rate regulation is assessed as a dynamical system operating in chaotic regimes. Radial-basis function (RBF) networks are applied as a tool for learning and predicting the HRV dynamics. HRV signals are analyzed from normal subjects before and after pharmacological autonomic nervous system (ANS) blockade and from diabetic patients with dysfunctional ANS. The heart rate of normal subjects presents notable predictability. The prediction error is minimized, in fewer degrees of freedom, in the case of diabetic patients. However, for the case of pharmacological ANS blockade, although correlation dimension approaches indicate significant reduction in complexity, the RBF networks fail to reconstruct adequately the underlying dynamics. The transient attributes of the HRV dynamics under the pharmacological disturbance is elucidated as the explanation for the prediction inability.

Atropine↗
PubMed2000

Automatic recognition of biological shapes with and without representations of shape.

In this work it is described how to use the curvature function, the Fourier descriptors, and the coordinate functions of a contour to achieve automatic recognition of biological shapes. Those representations of shape and the coordinate functions were applied to recognize human corneal endothelial cells embedded in a sample of tissue. We assume that when the coordinates of the points of contours are analyzed directly, no representation of shape is being used. We applied scale-space filtering to the coordinate functions, to compensate the effects of scaling and to minimize the error due to quantization. A technique for compensating the effects of rotation, with or without the use of a representation of shape, is proposed. Our results show that, for a wide range of biological shapes, no representation of shape is required to solve or avoid the problems caused by translation, scaling, and rotation. We conclude that for certain applications the use of a representation of shape can provide some advantages. However, the coordinate functions of contours, evolved in scale-space, can be efficiently used, yielding even better results in applications of robotics and computer vision related to the recognition of biological shapes.

Cell Biology↗
PubMed2000

Dose uniformity and redispersibility of pharmaceutical suspensions 2: assessment of three commercial erythromycin ethyl succinate oral liquids.

The content of active ingredient of single doses of a suspension depends to a large extent upon the redispersibility of the product. Mathematical and technical aspects of a procedure to test this property have been discussed in a preceding article. Here, the method is applied to three commercial erythromycin ethylsuccinate suspensions obtained from community pharmacies in Germany. Three specimens of each product were tested in parallel. For approximately two weeks, samples were taken t.i.d. at 9 am, 1 pm and 5 pm after shaking the bottles on a prototype testing apparatus with an intensity of 134m(2)/s(3) per cycle corresponding to the 25th percentile of a group of 79 subjects, whose shaking habits had been assessed previously. In order to minimize volumetric errors, 2.5ml samples were drawn using a syringe. They were assayed by HPLC with electrochemical detection using oleandomycin as an internal standard. While one of the products performed satisfactorily and one showed moderate shortcomings, the dose uniformity of two specimens of the third product was clearly deficient. The problem seems to be associated with poor wetting behaviour of the solids.

Administration, Oral↗
PubMed2002

Risk management for the endoscopy center.

Risk management, as applied to practice in the endoscopy center, is a framework of processes that attempt to minimize medical errors, prevent adverse events and patient injury, reduce the probability of malpractice actions being brought, and limit the financial and personal psychological costs that accompany malpractice lawsuits. This article summarizes the components of these processes, building on a foundation of applied legal concepts and pertinent malpractice claim data.

Ambulatory Surgical Procedures↗
PubMed2006

Evaluating sample medications in primary care: a practice-based research network study.

BACKGROUND: No reports have objectively evaluated safety of samples in primary care practices. A study was conducted to determine adherence to the Institute for Safe Medication Practices (ISMP) recommendations for safe distribution of medication samples to minimize medication errors. METHODS: In 2004, 17 urban and rural primary care practices participated in a two-phase observational study: (1) a site visit to collect inventory data and perform assessment of medication sample dispensing procedures and (2) a survey questionnaire for providers and patients upon sample medication provision. RESULTS: No practices were compliant with all seven ISMP recommendations. Twelve of 17 practices had policies for sample medication dispensing, and 7 had policies for labeling. Sample medication use was evaluated for 585 office visits and 27 patient surveys. Fifty-eight sample medications were dispensed during 55 of 585 patient visits. Common reasons for using sample medications included availability and need for a short-term trial for a chronic medication. Verbal communication only was provided most of the time for patient education regarding appropriate sample medication use and side effects. DISCUSSION: Primary care practices in this research network did not follow safe and appropriate sample medication dispensing procedures as outlined by ISMP. Both labeling and patient instructions were inadequate and may increase the risk for medication errors.

Colorado↗
PubMed2002

Analytical methods to investigate glutathione and related compounds in biological and pathological processes.

Reduced glutathione (GSH, gamma-L-glutamyl-L-cysteinylglycine) is a fundamental low-molecular mass antioxidant that serves several biological functions. Upon enzymatic and non-enzymatic oxidation, GSH forms glutathione disulfide (GSSG) and, under particular conditions, may generate other oxidative products. The determination of GSH, its precursors, and metabolites in several bio-matrices is a useful tool in studying oxidative stress. Many separative and non-separative methods have been developed and improved for the assay of GSH and related compounds. At present, high-performance liquid chromatography and capillary electrophoresis are the most used separative techniques to determine GSH and congeners. The review will deal with analytical methods developed over the last few years for the determination of GSH and related compounds, and with the procedures performed in sample pre-treatment in order to minimize analytical errors. Since GSH, GSSG, and related compounds lack of strong chromophores or fluorophores, it is advantageous, in many assays, to derivatize the compounds in order to improve the detection limit with UV-Vis and to allow fluorescence, thus the most commonly used labeling agents are also described.

Chromatography↗
PubMedDate not supplied

Some visual and neurochemical correlates of refractive development.

Increasing evidence indicates that the retina takes part in the postnatal regulation of eye growth, functioning in this respect to minimize refractive error. The evidence derives both from clinical observations in man and from experiments in animals. The discovery that visual form deprivation leads to an axial overgrowth of the eye and to myopia has opened the way to many current research initiatives. Neurochemical and immunocytochemical experiments in chick and monkey suggest that definable retinal neurons participate in the regulatory pathway controlling eye growth. The most comprehensive data presently implicate dopaminergic amacrine cells. Other important issues to be addressed include the relevance of an intact connection to the central nervous system and the precise retinal mechanism by which eye growth is regulated.

Animals↗
PubMed2005

General approach to high-efficiency simulation of affinity capillary electrophoresis.

The differential equation describing electrophoretic migration can be evaluated with various finite difference schemes (FDSs). However, the accuracy and efficiency can be dramatically different depending on the FDS chosen and the way the algorithm is implemented in a computer simulation program. The monotonic transport scheme is used as the algorithm for the hyperbolic part of the differential equation, and the first-order fully explicit scheme is used for the parabolic part of the equation. The combination of these algorithms minimizes the errors and maintains high efficiency. A circular arrangement of the cells in the computer's memory is used in the implementation of the algorithms, and the use of concentration thresholds to enable and disable cells along the capillary makes the new algorithm highly efficient. Either thermodynamic or kinetic constants can be used in this program to simulate binding interactions between two species for equilibrium and nonequilibrium affinity CE. Simulation results with various parameters are presented. The simulated peak with proper parameters for an equilibrium affinity CE experiment has shape and position similar to that of the experimental peak. The simulated electropherograms for a nonequilibrium affinity CE experiment also show characteristics of the experimental electropherograms.

Journal Article↗