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PubMed2005

Human chromosome 21/Down syndrome gene function and pathway database.

Down syndrome, trisomy of human chromosome 21, is the most common genetic cause of intellectual disability. Correlating the increased expression, due to gene dosage, of the >300 genes encoded by chromosome 21 with specific phenotypic features is a goal that becomes more feasible with the increasing availability of large scale functional, expression and evolutionary data. These data are dispersed among diverse databases, and the variety of formats and locations, plus their often rapid growth, makes access and assimilation a daunting task. To aid the Down syndrome and chromosome 21 community, and researchers interested in the study of any chromosome 21 gene or ortholog, we are developing a comprehensive chromosome 21-specific database with the goals of (i) data consolidation, (ii) accuracy and completeness through expert curation, and (iii) facilitation of novel hypothesis generation. Here we describe the current status of data collection and the immediate future plans for this first human chromosome-specific database.

Base Sequence↗

PubMed1999

Stages of increased cerebral blood flow accompany stages of rapid brain growth.

Stages of increased cerebral blood flow accompany stages of rapid brain growth The existence of stages of rapid brain growth implies the existence of associated stages of increased cerebral blood flow (CBF) to supply the substances and energy needed for the added brain weight. Studies in the literature give developmental data for CBF in humans which show stages of increased cerebral blood flow at ages starting just preceding and/or coincident with the ages of the rapid brain growth stages. Confirmation of the implication for one of the earliest stages is also found in PET data. Additionally, data for rodents show a similar association of stages of increasing CBF and their brain growth stages. Thus, to the accuracy of the data, the implication is confirmed. Finding stages in cerebral blood flow predicts the existence of stages of brain growth. In addition; finding correlated blood flow stages also supports the age spans of the stages of rapid brain growth in both species. Such correlations also suggest that measurements of blood flow anywhere in the body might serve to reveal rapid growth stages in particular localities or organs if the blood flow shows significant stages. The ratio of energy consumed in brain to that in total body decreases from close to 100% at birth to the adult value of about 20% by age 18 years.

Adolescent↗

PubMed1987

Thallium scintigraphy in prediction of occlusion of bypass grafts in asymptomatic and symptomatic patients.

To evaluate thallium scintigraphy in predicting coronary artery bypass graft patency, exercise thallium scintigraphy and selective graft and native vessel angiograms were performed in 22 asymptomatic and 29 symptomatic consecutive patients three months after coronary artery bypass grafting (CABG). Twelve out of 22 asymptomatic patients (55%) had reversible thallium defects on postoperative images; in 10 patients the postoperative scans were normal. The graft patency was significantly lower in asymptomatic patients with abnormal thallium perfusion compared to those with normal perfusion after CABG (68% vs. 91%, p less than 0.05). The rate of graft patency in symptomatic patients was 66/87 (76%). Thallium scintigraphy was 77% sensitive and 78% specific in detecting one or more stenosed or occluded bypass grafts in patients without angina (accuracy 77%). When data from exercise electrocardiography were combined with scintigraphy, all but one patient with incomplete revascularization could be detected (positive predictive accuracy 92%). In symptomatic patients, thallium scintigraphy accurately predicted the presence or absence of graft occlusion in 24/29 (83%) cases. Thus, abnormal myocardial perfusion due to stenosis or occlusion of bypass grafts is common in both asymptomatic and symptomatic patients after CABG. Thallium scintigraphy together with exercise electrocardiography appear to be useful non-invasive methods in detecting painless myocardial ischemia and in predicting bypass graft occlusion after CABG.

Adult↗

PubMed1976

The influence of induced abortion on Taiwanese fertility.

Data on the outcomes of more than 15,000 pregnancies originating between May 1966 and February 1969 were analyzed. The accuracy of the data was evaluated, rates of induced abortion and stillbirth were reported, and the demographic effect of induced abortion was estimated. The demographic effect was defined as the percentage increase in fertility that would have occurred in the absence of induced abortion, assuming no compensating change in alternative fertility control practices. Our principal findings were as follows: 1. We were unable to determine the completeness with which induced abortion was reported in the Registration Study. During the three years covered by the study, rates of induced abortion increased by 54 percent, reflecting a trend in the incidence or in the reporting of events or in both. We concluded that, in any case, the data for the final year of the study, 1968, were more complete than for the earlier two years. 2. Age-specific rates of induced abortion for 1968 displayed a strong urban-rural gradient, being much higher in the city areas than in the rural areas. Within each urban--rural stratum, the rates increases monotonically with age and reached maximum values in the age group 40 and older (553, 436, and 374 per 1,000 pregnancies for city, urban, and rural areas, respectively). 3. Estimates of the demographic effect indicated that, in the absence of induced abortion, the TFR for all Taiwan would have been 12 percent higher in 1968. Under the same assumption, it was estimated that the TFR would have been higher by 16 percent in city areas, 11 percent in urban areas, and 9 percent in rural areas. This urbanization gradient implies that induced abortion contributed to urban-rural fertility differentials. We estimated that about one-third of those differentials were due to induced abortion. 4. Estimates of the demographic effect were also made after adjusting the rates of induced abortion for an assumed level of underreporting of 50 percent. The adjusted estimate of the demographic effect for all Taiwan in 1968 was 19 percent.

Abortion, Induced↗

PubMed2005

Accuracy and robustness of three-way decomposition applied to NMR data.

Three-way decomposition is a very versatile analysis tool with applications in a variety of protein NMR fields. It has been used to extract structural data from 3D NOESYs, to determine relaxation rates in large proteins, to identify ligand binding in screening for lead compounds, and to complement non-uniformly recorded (sparse) spectra. All applications so far concerned experimental data sets; it thus remains to address questions of accuracy and robustness of the method using simulated data where the correct answer is known. Systematic tests are presented for relaxation and NOESY data sets. Mixtures of real and synthetic data are used to allow control of various parameters and comparisons with correct reference data, while working with input that is as realistic as possible. The influence of the following parameters is evaluated: signal-to-noise, overlap of signals and the use of a regularization procedure within the algorithm. The main criteria used for the evaluation are accuracy and precision. It is shown that deterioration of accuracy is indicated by internal checks such as decrease of precision. Both with relaxation data and when interpreting NOESY spectra, three-way decomposition exhibits a robust behavior in situations with severe signal overlap and/or poor signal-to-noise, e.g., by avoiding false positives in the NOE shapes of NOESY decompositions. As a complement to this study, three-way decomposition is compared to other methods that achieve the same type of results.

Algorithms↗

PubMed2005

Region-of-interest-based analysis of clustered BOLD MRI data in experimental arthritis.

RATIONALE AND OBJECTIVES: BOLD MRI provides functional information based on minimal changes. Problems inherent in data processing of the very low signal-to-noise-ratio of BOLD experiments have created obstacles for validation of certain techniques using standard strength-field MR scanners. Measures of diagnostic accuracy of clustered data are directly related to the reading parameters used to define regions-of-interest (ROIs). Our primary aim was to determine the combination of ROI-related reading parameters that provides highest accuracy for discrimination of presence or absence of arthritis in acute and subacute stages of the disease using paired comparisons of BOLD MRI data. MATERIALS AND METHODS: Six male New Zealand white rabbits were injected with albumin into one knee and saline into the contralateral knee, 3 animals had albumin injected into only one of the knees, 2 had saline injected into one of the knees, and 3 animals were not injected. The rabbits' knees underwent BOLD MRI on days 1 and 28 after induction of arthritis, except for the knees of 3 animals (albumin- vs saline-injected knees, n = 2 animals; saline- vs noninjected knees, n = 1 animal) that died before expected and had only the first MRI examination done. Percentage of activated voxels and differences in on-and-off signal intensities were the BOLD MRI methods applied. Data were analyzed using anatomic-driven small ROI, voxel-chaser-driven small ROI and anatomic-driven large ROI techniques. RESULTS: Diagnostic areas-under-the curve (AUCs) were obtained only for acute arthritis and only when percentage of activated voxels was used. Low threshold, positive voxel activations and small ROIs generated the largest AUCs (AUC +/- SE, .911 +/- .092, P = .014) using either anatomic-driven or voxel-chaser-driven techniques. A sensitivity analysis confirmed the importance of threshold as a parameter for analysis. CONCLUSION: Low threshold, positive voxel activations and small ROIs constituted the set of reading parameters that provided the most accurate BOLD MRI results.

Animals↗

PubMed2006

Evaluation of transmission methodology and attenuation correction for the microPET Focus 220 animal scanner.

An accurate, low noise estimate of photon attenuation in the subject is required for quantitative microPET studies of molecular tracer distributions in vivo. In this work, several transmission-based measurement techniques were compared, including coincidence mode with and without rod windowing, singles mode with two different energy sources ((68)Ge and (57)Co), and postinjection transmission scanning. In addition, the effectiveness of transmission segmentation and the propagation of transmission bias and noise into the emission images were examined. The (57)Co singles measurements provided the most accurate attenuation coefficients and superior signal-to-noise ratio, while (68)Ge singles measurements were degraded due to scattering from the object. Scatter correction of (68)Ge transmission data improved the accuracy for a 10 cm phantom but over-corrected for a mouse phantom. (57)Co scanning also resulted in low bias and noise in postinjection transmission scans for emission activities up to 20 MBq. Segmentation worked most reliably for transmission data acquired with (57)Co but the minor improvement in accuracy of attenuation coefficients and signal-to-noise may not justify its use, particularly for small subjects. We conclude that (57)Co singles transmission scanning is the most suitable method for measured attenuation correction on the microPET Focus 220 animal scanner.

Algorithms↗

PubMed1999

Accuracy of intravascular microcatheter pressure measurements: an experimental study.

Intravascular pressure measurements are considered useful for the monitoring and assessment of endovascular treatment effects in intracranial vascular malformations. Experimental data on the accuracy of these measurements are limited. A flow phantom with defined intraluminal pressures and pulsatility flow waveforms was used in this study. Microcatheters commercially available for neuroendovascular procedures (length 140-155 cm), with different outer (0.5-0.83 mm) and inner (0.3-0.53 mm) diameters, were introduced into the phantom in the direction of flow. In a static experiment, pressure values from 0 to 75 mmHg were applied, and in the dynamic part of the experiment mean pressure values from 25 to 65 mmHg, with a pulsatile amplitude from 70 to 170 mmHg were employed. In the static experiment, there was a linear relationship between the pressure values obtained through the microcatheters and the local transducer of the flow phantom. The pulsatile experiments showed increased damping of the pressure waveforms with decreasing inner diameter of the microcatheters. However, the mean pressure values remained accurate. This experimental study has shown that mean pressure values can be accurately measured through microcatheters from 0.3-0.5 mm inner diameter and more than 140 cm in length. In vivo pressure measurements during interventional procedures are therefore reproducible and can be used for monitoring of embolization effects in patients.

Blood Flow Velocity↗

PubMed2002

Assessing allelic dropout and genotype reliability using maximum likelihood.

A growing number of population genetic studies utilize nuclear DNA microsatellite data from museum specimens and noninvasive sources. Genotyping errors are elevated in these low quantity DNA sources, potentially compromising the power and accuracy of the data. The most conservative method for addressing this problem is effective, but requires extensive replication of individual genotypes. In search of a more efficient method, we developed a maximum-likelihood approach that minimizes errors by estimating genotype reliability and strategically directing replication at loci most likely to harbor errors. The model assumes that false and contaminant alleles can be removed from the dataset and that the allelic dropout rate is even across loci. Simulations demonstrate that the proposed method marks a vast improvement in efficiency while maintaining accuracy. When allelic dropout rates are low (0-30%), the reduction in the number of PCR replicates is typically 40-50%. The model is robust to moderate violations of the even dropout rate assumption. For datasets that contain false and contaminant alleles, a replication strategy is proposed. Our current model addresses only allelic dropout, the most prevalent source of genotyping error. However, the developed likelihood framework can incorporate additional error-generating processes as they become more clearly understood.

Alleles↗

PubMed1992

Accuracy and analysis of ambulatory blood pressure monitoring data.

Two devices used to record blood pressure, the ambulatory blood pressure monitoring recorder and standard stethoscope and mercury column, were tested for accuracy against the direct intra-arterial blood pressure of patients at rest and during exercise. Recorders were found to be as accurate as mercury column measurement in patients at rest. A number of assessment techniques of ambulatory data are reviewed, including: calculation of mean or median pressures, assessment of blood pressure load, and integration of the area under the blood pressure curve over time. These have been applied during the daytime and nighttime hours. Blood pressure load and area under the blood pressure curve, using different threshold criteria for nighttime and daytime, are recommended because of their potentially closer relation to target-organ disease of hypertension than are office blood pressure readings.

Ambulatory Care↗

PubMed2004

High-resolution laser surface scanning for patient registration in cranial computer-assisted surgery.

OBJECTIVE: Markerless patient registration is a new procedure that may reduce logistical efforts and possibly also the radiation load on the patients prior to a computer-assisted intervention. Congruent surfaces, such as bone surfaces or skin surfaces, represented in a data set and in the surgical site, can be overlapped using surface-matching. Previous studies describing this kind of markerless registration, however, show inaccuracies of up to 10 mm during computer-assisted navigation. Furthermore, these systems use less than 1000 surface points of the soft tissue surface in order to establish a correlation between the patient and the data set. Previous papers did not answer the question whether it is this scanning resolution that induces these inaccuracies in registration or rather intraoperative skin deformations. STUDY DESIGN: In the present study therefore a new navigation system (SSN++) was used which is able to register up to 180,000 surface points of the surgical site. SSN++ is an infrared navigation system enlarged by a Minolta VI 900 3D volume digitizer. Three different kinds of laser scan-resolution were used for data correlation. An additional congruence analysis was performed in order to assess the geometry of the matched skin surfaces. 22 patients suffering from different cranial diseases (tumors, bony malformations, foreign bodies) were prepared for a computer-assisted intervention. Intraoral titanium-markers, rigidly fixed on the patients by a maxillary splint, were placed as targets while the CT data sets were made. These targets were - after markerless laser scan registration of the patients - supposed to serve for validating the new high-resolution navigation system SSN++. RESULTS: The accuracy of markerless laser scan registration depends on the intraoperative laser scan's resolution. A high accuracy of the data correlation can be achieved if the number of the laser scan cloud points is about the same as the number of voxels of the corresponding surface on the CT data set. A reduction of the laser scan cloud points to less than 10 % compared to the number of voxels of the CT surface, however, leads to a significant loss of accuracy after markerless patient registration. CONCLUSION: The markerless laser scan registration of the surgical site may achieve the same accuracy as a patient registration made by rigidly fixed titanium screws (mean accuracy: 1.2 mm) as long as a high-resolution laser scan is being used.

Brain Diseases↗

PubMed1987

Variable selection method improves the prediction of protein secondary structure from circular dichroism spectra.

A new procedure based on the statistical method of "variable selection" is used to predict the secondary structure of proteins from circular dichroism spectra. Variable selection adds the flexibility found in the Provencher and Glöckner method (S. W. Provencher and J. Glöckner, 1981, Biochemistry 20, 33-37) to the method of Hennessey and Johnson (J. P. Hennessey and W. C. Johnson, 1981, Biochemistry 20, 1085-1094). Two analytical methods are presented for choosing a solution from the series generated by the Provencher and Glöckner method, and this improves the technique. All three methods are compared and it is shown that both the variable selection method and the improved Provencher and Glöckner methods have equivalent reliability superior to the original Hennessey and Johnson method. For the new variable selection method, correlation coefficients calculated between X-ray structure and predicted secondary structures for data measured to 178 nm are: 0.97 for alpha-helix, 0.75 for beta-sheet, 0.50 for beta-turn, and 0.89 for other structures. Although the variable selection method improves the analysis of circular dichroism data truncated at 190 nm, data measured to 178 nm gives superior results. It is shown that improving the fit to the measured CD beyond the accuracy of the data can result in poorer analyses.

Circular Dichroism↗

PubMed2006

A hierarchical screening methodology for physicochemical/ADME/Tox profiling.

Full integration of pharmaceutical profiling into pharmaceutical lead selection and optimisation requires that complete sets of unequivocal data be available at the time compound design or advancement decisions are made. As the productivity of chemical synthesis expands, and the breadth of profiling assays grow in scope, physicochemical/ADME/Tox laboratories are being challenged to produce ever more data to support an accelerating decision cycle. This article focuses on the challenges of increasing preclinical profiling productivity while managing lower accuracy higher throughput data streams to preserve confidence in decision making. The authors propose a hierarchical screening strategy and describe the implementation of an automated system designed to support that strategy efficiently.

Automation↗

PubMed2006

Technical description, phantom accuracy, and clinical feasibility for fiducial-free frameless real-time image-guided spinal radiosurgery.

OBJECT: The authors describe the technical application of the Xsight Spine Tracking System, data pertaining to accuracy obtained during phantom testing, and the initial clinical feasibility of using this fiducial-free alignment system with the CyberKnife in spinal radiosurgery. METHODS: The Xsight integrates with the CyberKnife radiosurgery system to eliminate the need for implantation of radiographic markers or fiducials prior to spinal radiosurgery. It locates and tracks spinal lesions relative to spinal osseous landmarks. The authors performed 10 end-to-end tests of accuracy using an anthropomorphic head and cervical spine phantom. Xsight was also used in the treatment of 50 spinal lesions in 42 patients. Dose planning was based on 1.5-mm-thick computed tomography slices in which an inverse treatment planning technique was used. All lesions could be treated using the fiducial-free tracking procedure. Phantom tests produced an overall mean targeting error of 0.52 +/- 0.22 mm. The setup time for patient alignment averaged 6 minutes (range 2-45 minutes). The treatment doses varied from 12 to 25 Gy to the median prescription isodose of 65% (40 to 70%). The tumor volume ranged between 1.3 and 152.8 cm3. The mean spinal cord volume receiving greater than 8 Gy was 0.69 +/- 0.35 cm3. No short-term adverse events were noted during the 1- to 7-month follow-up period. Axial and radicular pain was relieved in 14 of 15 patients treated for pain. CONCLUSIONS: Fiducial-free tracking is a feasible, accurate, and reliable tool for radiosurgery of the entire spine. By eliminating the need for fiducial implantation, the Xsight system offers patients noninvasive radiosurgical intervention for intra- and paraspinal tumors.

Adolescent↗

PubMed2003

Disparity in coding concordance: do physicians and coders agree?

Increasing demands for large-scale comparative analysis of health care costs has led to a similar demand for consistently classified data. Evidence-based medicine demands evidence that can be trusted. This study sought to assess managers' observed levels of agreement with physician code selections when classifying patient data. Using a non-sampled research design of both mailed and telephone surveys, we employ a nationwide cross-section of over 16,000 accredited US medical record managers. As a main outcome measure, we evaluate reported levels of agreement between physician and information manager code selections made when classifying patient data. Results indicate about 19 percent of respondents report that coder-physician classification disagreement occurred on more than 5 percent of all patient encounters. In some cases, disagreement occurred in 20 percent or more instances of code selection. This phenomenon shows significant variation across key demographic and market indicators. With the growing practice of measuring coded data quality as an outcome of health care financial performance, along with adoption of electronic classification and patient record systems, the accuracy of coded data is likely to remain uncertain in the absence of more consistent classification and coding practices.

Data Collection↗

PubMedDate not supplied

Non-specific tumoral markers in hepatocellular carcinoma.

The number of biological tumoral markers used in the diagnosis and therapy monitoring of hepatocellular carcinoma has increased, but their separate use is limited as none of them is specific, being only tumour-associated (proteins). But when in abnormal amounts and used in combination, they are of great help in the diagnosis and therapy monitoring. A combination of alpha-fetoprotein (AFP) and alpha 1-antitrypsin (AAT) data raises the diagnostic accuracy in hepatocellular carcinoma from 43% obtained with AFP alone, to 90.5% and if the combination includes the carcinoembryonic antigen (CEA) data too the accuracy increases to 100%, still without strict specificity for hepatocellular carcinoma.

Acute-Phase Proteins↗

PubMed1990

Five years' experience of injured children.

This study was undertaken to analyse admission data on all patients seen in the Red Cross War Memorial Children's Hospital Trauma Unit during the period 24 April 1984 - 31 March 1989. Data were retrieved from computerised records completed on admission and were reviewed descriptively. Variations in age, sex and population group pattern for different causes of injury were evaluated together with data on the nature and place of injury and time seen. Data for analysis of nature of injury by cause were also retrieved, but over a 2-year period only (1986-1987). Accuracy of recorded data was assessed from a random sample of hospital records. During the 5-year period 57,468 patients were seen in the Trauma Unit, of whom 17.1% were admitted. In addition 6,377 cases of poisoning and 119 of near-drowning were seen by the medical departments. Forty-three per cent of injuries were due to falls, which were the most important cause of injury in both admitted and non-admitted patients of all age, sex and population groups. Other main cause groups were bumps and blows (15%), transport (11%) and burns (11%). Transport and burn injuries had the highest admission rates. This is the first study of children's injuries in southern Africa and provides information essential to future design of paediatric trauma care systems and accident prevention programmes.

Accidents, Traffic↗

PubMedDate not supplied

Xeroradiography--a method for exploring the thyroid gland pathology.

The authors discuss the diagnostic value of xeroradiography, an up-to-date method elaborated and applied for the first time in diagnosing thyroid pathology. Emphasis is placed on the method as it affords on the same xerogram a very good image of the soft tissues and bones. A xeroradiographic image of the cervical and cervico-lateral areas allows an assessment of the position, volume and other changes in the same area. The authors insist that the data gathered in this way allow a more correct evaluation needed in establishing the surgical procedure and in traheoanesthesia. The diagnostic accuracy of the data obtained in 50 cases of various forms of thyroid pathology, compared to the intraoperatory data as well as the fact that the method creates no discomfort to the patient enable the authors to recommend thyroid xeroradiography as a valuable, non-invasive method now available to the endocrine clinician, especially to the endocrine surgeon and anesthesist.

Humans↗