Post abortion syndrome?
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Abortion, Induced↗
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[The effect of sampling error on results of inverse projection: an empirical study].
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Demography↗
[Plethysmographic measurement of lung volume in chronic obstructive pulmonary disease. Influence of the panting pattern].
In 9 healthy subjects and 22 patients with chronic obstructive disease, we computed total lung capacity (TLC) using an integrated flow pressure-corrected body plethysmograph. During panting manoeuvre, TLC derived from oesophageal pressure (TLCes) was compared to TLC derived from mouth pressure (TLCm). In healthy subjects, TLCm was identical to TLCes. Patients with obstructive disease exhibited different behaviours according to experimental conditions: a) in free frequency panting with mouth occlusion close to functional residual capacity (FRC) (9 patients), TLCm appeared to be significantly higher than TLCes (mean difference: 0.25 1; p less than 0.05); b) in panting with both low (less than 1 Hz) and high (2 Hz) frequencies and mouth occlusion close to FRC (7 patients), TLCm appeared to be significantly higher than TLCes only at a high frequency (p less than 0.05); c) in panting with both low and high frequencies and mouth occlusion close to TLC (6 patients), no significant difference was observed between TLCm and TLCes. These results suggest that in patients with chronic obstructive disease plethysmographic lung volume measurements are subject to error, due to the influence of extrathoracic airways. During occlusion at FRC, panting frequency was found to influence the results obtained, the error being minimized with low frequencies. In contrast, by occluding at TLC, we found that panting frequency was less likely to influence the results. However, potential sources of error still exist: for instance, the influence of abdominal gas or the panting pattern.
Adult↗
Absolute rates of cholesterol synthesis in extrahepatic tissues measured with 3H-labeled water and 14C-labeled substrates.
This study was undertaken to develop techniques for measuring absolute rates of sterol synthesis in extrahepatic tissues in vitro and to estimate the magnitude of the errors inherent in the use of various 14C-labeled substrates for such measurements. Initial studies showed that significant errors were introduced when rates of synthesis were estimated using [3H]water since about 20 nmol of water were bound to each mg of tissue cholesterol isolated as the digitonide. This source of error could be eliminated by subtracting apparent incorporation rates obtained at 0 degrees C from those obtained at 37 degrees C or by regenerating and drying the free sterol. In a second set of experiments, the H/C incorporation ratio in cholesterol was determined in the liver by measuring the absolute rates of hydrogen and acetyl CoA flux into sterols. The ratio of 0.69 +/- 0.03 was found to be independent of the rate of hepatic cholesterol synthesis, the rate of hepatic acetyl CoA generation, or the source of the acetyl CoA. In a third set of studies, rates of incorporation of [3H]water or 14C-labeled acetate, octanoate, and glucose into digitonin-precipitable sterols were simultaneously measured in nine different extrahepatic tissues. Assuming that the H/C ratio measured in the liver also applied to these tissues, the [3H]water incorporation rates were multipled by the reciprocal of the H/C ratio to give the absolute rates of sterol synthesis in each tissue. When these were compared to the incorporation rates determined with the 14C-labeled substrates the magnitude of the errors in the rates of sterol synthesis obtained with these substrates in each tissue could be assessed. Only [14C]octanoate gave synthesis rates approaching 100% of those obtained with [3H]water and this occurred only in the intestine and kidney; in the other extrahepatic tissues this substrate gave rates of 6--66+ of the absolute rates. Rates of [14C]acetate incorporation in sterols varied from 4 to 62% of the [3H]water incorporation rates while those obtained with [14C]glucose were only 2--88% of the true rates. These studies document the large and highly variable errors inherent in estimating rates of sterol synthesis in extrahepatic tissues using 14C-labeled substrates under in vitro conditions.
Acetates↗
Source monitoring in eyewitness memory: implicit associations, suggestions, and episodic traces.
Both the distinctiveness heuristic and discrepancy detection hypotheses were investigated by independently manipulating both schema consistency and incidental suggestion in an eyewitness memory paradigm. A sequence of slides was shown, followed by a postevent questionnaire that contained both schema-typical and schema-atypical information. Fifteen minutes later, a source-monitoring task was administered. In Experiment 1, the proportion of source misattribution errors was greater for schema-typical items than for schema-atypical items, and the proportion of errors on suggested items was greater than that on control items. Suggestion affected schema-typical and schema-atypical items equally, providing no support for the predictions of either hypothesis. In Experiment 2, the interval between the questionnaire and the source test was manipulated. The results of Experiment 1 were replicated under the short delay, whereas the proportion of errors increased under the long delay. An associative network model involving two types of episodic traces was used to account for the results.
Association↗
Geometric analysis of potential error in using femoral intramedullary guides in total knee arthroplasty.
Proper component orientation is necessary for the long-term success of a total knee arthroplasty. Femoral component placement has used jigging systems that are based on intramedullary and extramedullary guides. The intramedullary system has been shown to foster more accurate and reproducible placement of the femoral component. This study analyzed and quantified the potential error of the intramedullary guide system. Geometric data of the human femur were obtained from radiographs of 45 cadaver femora in the anteroposterior and lateral views. The correct entry point of the intramedullary rod in the distal femur is the midaxial line of the femoral canal on anteroposterior and lateral radiographs. The position of this point in relation to the mediolateral and anteroposterior dimensions of the distal femur was calculated as a ratio. The average calculated ratios were anteroposterior, 0.53 offset medially; lateral, 0.32 offset anterior. Mathematical models were constructed to quantify the potential varus valgus and flexion extension error of the guide rods. Variables investigated were entry point location, guide rod diameter, guide rod length, and rotation. The surgeon must be cognizant of these potential sources of error to maximize the accuracy of the femoral intramedullary jigging system.
Arthroplasty, Replacement, Knee↗
Evaluating models of collinearity judgment for reliability and scale.
In prior work from this laboratory, we have examined how accurately subjects can judge collinearity, i.e. alignment, as a function of the angular position of stimulus elements. In those experiments, subjects were presented with a line segment (or a pair of dots) which varied across the 360 degrees range of angular positions, and were required to select and mark a point which was perceived as being collinear. We found that the models of error for each subject consisted of a complex set of peaks and valleys which are herein described as delta excursions. The error tendencies appeared to be idiosyncratic, in that each subject manifested a different profile of these excursions. Here we report the results of three experiments. In the first, we tested subjects across five sessions, and found that the five models of error were fairly comparable for a given subject. In the second and third experiments, we tested at close intervals of angular position, and found evidence for localized sources of error. We continue to find that the error model for each subject is idiosyncratic, and argue that the excursions may be due to defects in a system which combines responses from position-encoding fields that vary in size.
Analysis of Variance↗
Potential errors in the application of mixture theory to multifrequency bioelectrical impedance analysis.
Potential errors in the application of mixture theory to the analysis of multiple-frequency bioelectrical impedance data for the determination of body fluid volumes are assessed. Potential sources of error include: conductive length; tissue fluid resistivity; body density; weight and technical errors of measurement. Inclusion of inaccurate estimates of body density and weight introduce errors of typically < +/- 3% but incorrect assumptions regarding conductive length or fluid resistivities may each incur errors of up to 20%.
Adult↗
Near infrared spectroscopy as a tool for the determination of eumelanin in human hair.
Eumelanins are brown-black pigments present in the hair and in the epidermis which are acknowledged as protection factors against cell damage caused by ultraviolet radiation. The quantity of eumelanin present in hair has recently been put forward as a means of identifying subjects with a higher risk of skin tumours. For epidemiological studies, chromatographic methods of determining pyrrole-2,3,5-tricarboxylic acid (PTCA; the principal marker of eumelanin) are long, laborious and unsuitable for screening large populations. We suggest near infrared (NIR) spectroscopy as an alternative method of analysing eumelanin in hair samples. PCTA was determined on 93 samples of hair by means of oxidizing with hydrogen peroxide in a basic environment followed by chromatographic separation. The same 93 samples were then subjected to NIR spectrophotometric analysis. The spectra were obtained in reflectance mode on hair samples which had not undergone any preliminary treatment, but had simply been pressed and placed on the measuring window of the spectrophotometer. The PTCA values obtained by means of HPLC were correlated with the near infrared spectrum of the respective samples. A correlation between the PTCA values obtained by means of HPLC and the PTCA values obtained from an analysis of the spectra was obtained using the principal component regression (PCR) algorithm. The correlation obtained has a coefficient of regression (R(2)) of 0.89 and a standard error of prediction (SEP) of 13.8 for a mean value of 108.6 ng PTCA/mg hair. Some considerations about the accuracy of the obtained correlation and the main sources of error are made and some validation results are shown.
Chromatography, High Pressure Liquid↗
Influence of bright intramural echoes on estimates of ultrasonic attenuation from backscattered ultrasound in excised myocardium.
The purpose of this study was to quantitate the influence of bright intramural echoes on estimates of myocardial attenuation from analyses of backscattered ultrasound. To achieve this, M-mode image-based measurements of the inherent anisotropic properties of myocardial attenuation were performed on rotating myocardial specimens. The approach was to use a commercially-available ultrasonic imaging system to acquire M-mode images of 24 excised cylindrical specimens from six formalin-fixed lamb hearts for data analysis using a video signal analysis technique. As a control, through-transmission rf-based measurements were performed concurrently using a pair of focused, single-element ultrasonic transducers. We devised an objective approach to compensate M-mode results for the presence of bright intramural echoes that makes use of the rotational symmetry of the measurements. A comparison of the uncompensated and compensated estimates of attenuation shows that the effect of bright intramural echoes under the conditions of this study increases the average error in M-mode results by approximately 240% compared with that observed when such effects are minimized by compensation. For both uncompensated and compensated M-mode results, increased temporal averaging shows only a modest reduction in average error. These data suggest that for measurements of attenuation from backscattered ultrasound using M-mode images, the effects of bright intramural echoes can be a significant source of error despite increased temporal averaging and therefore may require compensation.
Animals↗
[Clinical reasoning in neurology].
There is much neurological literature on clinical, pathological, technical aspects of diagnostic or therapeutic aspects, however there are few articles about clinical-neurological reasoning. This paper analyzes the psychological processes by which neurologists solve complicated diagnostic problems. Clinicians can use a variety of reasoning, such as model (pattern), exhaustive, probabilistic, deterministic (categorical), and hypothetical-deductive reasoning mechanisms. The neurologist must be aware of what kind of reasoning is being used at a given time as well as the errors that can occur. Most of these errors are found in the probabilistic setting and can be grouped into three categories: representativeness errors, availability or adjustment and anchoring biases. Most of them occur due to an inadequate intuitive judgement by the physician to handle the probabilities. There are other sources of error, related with the diagnostic process or with the environmental circumstances in which they develop. The most important ones as well as their theoretical and practical implications are described. In the evidence based medicine era, it is important for the clinical neurologists to be aware of this terminology and concepts for an adequate practice of neurology.
Decision Making↗
Complications of shoulder instability surgery.
Complications of shoulder instability surgery may results from errors made during the preoperative, intraoperative, or postoperative periods. Some complications are preventable whereas the risk of others can be reduced. A few complications remain unpreventable. Two sources of error in the preoperative period that can lead to complications are an incorrect diagnosis and failure to address a patient's expectations of treatment. These errors and their subsequent complications are preventable. Preventing complications during the intraoperative period begins with proper patient positioning and a thorough knowledge of shoulder anatomy. Understanding the indications and limitations of the various stabilization procedures, as well as applying proper surgical technique, is essential to avoid a surgical misadventure. Complications recognized in the postoperative period include recurrent instability, limitation of motion, inability to return to the previous level of sport, problems related to hardware, pain, development of osteoarthritis, and neurovascular injuries. Infection and hematoma formation may also occur; both need to be recognized and treated early to maximize outcome. A protocol for treating each complication that may occur often is helpful. Knowledge of the complications that can arise is paramount to preventing their occurrence. This knowledge comes through experience, study, and continued research.
Arm Injuries↗
[Organ volume determination by computer tomography. I. The estimation of organ sectional areas with special reference to possible errors (author's transl)].
With the aid of computer tomography it is possible to determine the volume or organs by obtaining an adequate number of CT cuts through the area of interest, and by marking the organ contours. Various sources of error must be taken into account when using this method; some of these are systematic and others accidental. In particular it must be remembered that there may be errors in obtaining cross-sectional areas from the organ contours, since these vary depending on the chosen parameters, such as window level and position. These relationships, which depend on the apparatus, are developed theoretically and confirmed by measurements. It is shown that errors depend not only on the choice of window level, but also on the shape and size of the organ and on the surrounding contrast. It follows that it is possible to introduce corrections for the cross-sectional area, but that the size and shape of the section need to be taken into account, at least to some extent.
Anatomy↗
Errors in interpreting the pretransfusion bedside compatibility test: an experimental study.
BACKGROUND AND OBJECTIVE: Analysis of reports of incidents, involving ABO incompatibility suggests that the main problem is poor interpretation of the pretransfusion bedside compatibility test (PBCT). We studied sources of error as experienced by nurses as to the blood groups of donor blood and of the recipient. MATERIALS AND METHODS: According to their seniority in the profession and on the ward, 48 nurses were randomly selected from four transfusion sectors of the University Hospital of Grenoble, France. Each nurse interpreted 24 photos of PBCTs, including some with procedural irregularities, and was asked to assess the compatibility of the blood types of the donor and the recipient. At random, half the nurses were provided with a diagram to facilitate interpretation. RESULTS: The overall frequency of errors was 39.8%. Errors were fewer when the tests were interpreted as compatible (7.3%) or incompatible (6.3%), and when the nurse had been in the profession between 3 and 5 years and in the ward less than 3 years (25.5%), or worked in hematology (34.7%) or anesthesia (36.5%). Use of the diagram limited the number of errors, provided the test was interpretable (22.2%). CONCLUSION: PBCTs cannot be considered a valid safety procedure. We need other, more effective methods to reduce the risk of incompatibility accidents.
ABO Blood-Group System↗
Ideomotor apraxia and cerebral dominance for motor control.
Ideomotor apraxia is a symptom of left hemisphere damage. Patients with ideomotor apraxia commit errors when imitating movements with their left, non-paralyzed hand. This has been taken as evidence for a motor dominance of the left hemisphere. It has been hypothesized that the left hemisphere is dominant for internal preprogramming of skilled movements of either hand. We investigated the kinematics of movement trajectories of imitation of meaningless gestures. Group analysis confirmed that hesitant, feedback-controlled movement prevail in patients with apraxia, but analysis of single cases revealed the existence of kinematically normal movements leading to apractic errors. Enhanced reliance on feedback-control appears to be a compensatory strategy rather than the source of apractic errors. In a second study we explored the alternative hypothesis that patients with apraxia lack a general concept of the human body which is necessary to mediate the translation of a target position seen on the model into a target position on the patient's body. Imitation of movements was examined on oneself and on a mannikin. Patients with apraxia who made errors when imitating on themselves committed errors also when imitating on the mannikin. Taken together, both studies support the view that the source of errors in the imitation of gestures is to be sought at a conceptual level. This casts doubts on the alleged dominance of the left hemisphere for motor control.
Apraxias↗
Linear interpolation error in measured surfaces in a dental erosion study.
An extensive palatal erosion study, which is currently being undertaken at the University of Dundee, aims to detect erosion through the precise mapping of replicas of children's incisors. All perceived sources of error are being scrutinised closely. The error due to the interpolation of surface positions from discrete point measurements has been investigated so that its contribution to the erosion estimates can be gauged. The calculation of the error statistics made use of covariance functions to express the undulation of the tooth surfaces. It has been found that, for the measurement point spacing of 150 microm being used in the current project, the interpolation error for an incisor is typically about 25 microm, to be compared with the root-mean-square error due to tooth impression and replication procedures, assessed as being in the order of +/- 3 microm, and replica measurement, assessed as being in the order of +/- 5 microm. The interpolation error constitutes a surprisingly large proportion of the overall system error. The same error estimation technique can be applied usefully and without difficulty to other research studies concerning erosion or wear in natural or restorative dental surfaces.
Child↗
The effect of inaccuracies in death certification and coding practices in the European Economic Community (EEC) on international cancer mortality statistics.
An investigation into the effect of national death certification and coding practices on published mortality statistics in eight EEC countries is reported. Doctors in each country were asked to complete specimen death certificates for a bank of written case histories. Certificates from each country were coded by their own offices and then by a WHO reference centre. Within and between countries, discrepancies occurred both in the doctors' diagnoses and in the codes assigned to certificates. At an international level these differences had serious implications for the comparability of mortality data for cancers of the cervix and uterus, and for mesotheliomas.
Cause of Death↗
Computer-aided volume measurement of choroidal melanomas.
Using a combination of conventional B-scan ultrasonography, standard video techniques, computer image digitization and area analysis, it is possible to measure the volume of choroidal melanomas by area calculation of successive ultrasound image slices, allowing the monitoring of such tumors. The design of a combined water-bath and linear tracking B-scan transducer is presented, together with a description of the instrumentation and computer software required. The results of volume measurements performed upon eye models demonstrated that melanomas of volume greater than 100 mm3 could be measured with an average error of 6%. The problems associated with linear calibration of the system from scan-head to analysed image, resolution of the digitised image, reproducibility of the measurements, sources of error and assumptions made in formulating the measurement procedure are discussed.
Adult↗