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PubMed1990

PC-based system for collection and analysis of physiological data.

A personal computer based system for data acquisition and analysis appropriate to physiological experiments is described in detail. The system is independent of the details of the analog signal generation. The software, written in C, is modular and easily portable to other PC systems. The system is capable of: (a) sampling many analog signals at an appropriate rate (100 Hz), (b) storing large quantities of digitized data, (c) analysing digitized waveforms to obtain signal parameters, and (d) storing signal parameters in a format suitable for statistical analysis. Computer processed cardiopulmonary data are compared with data derived from standard ICU equipment.

Algorithms↗
PubMed1990

Functionality of the ARPIA ambulatory information system.

Although database-based medical information systems are becoming popular, experiments done by researchers tell us that physicians still do not fully accept them. Key factors for changing physicians' practice habits are the availability of more powerful methods and tools for interactive data acquisition and retrieval. Problems involving human engineering usually require the identification of and experimentation with many novel approaches before the most suitable answer is discovered. ARPIA is an ambulatory information system experimenting on the effectiveness and acceptability (by medical users) of new intelligent and friendly interaction techniques and tools. In particular, it tests a novel flexible dialogue-based man-machine interface offering physical and logical data 'independence' during retrieval operations. Other features of the system are: a fast and robust data acquisition environment; a text- and picture-based data presentation and report generation facility; finally, a set of modules offering the ambulatory staff effective assistance in some extra complex interactive tasks. A user-oriented description of the main functionality of ARPIA is given; users' feedback summarizing almost 2 years of usage of the system is also reported.

Ambulatory Care Information Systems↗
PubMed2000

Stair-step artifacts with single versus multiple detector-row helical CT.

PURPOSE: To compare the effects of acquisition parameters on the magnitude and appearance of artifacts between single and multiple detector-row helical computed tomography (CT). MATERIALS AND METHODS: A cylindric (12.7 x 305.0-mm) acrylic rod inclined 45 degrees relative to the z axis was scanned at the isocenter and 100 mm from the isocenter with single detector-row (single-channel) helical CT (beam width, 1-10 mm; pitch, 1.0, 2.0, or 3.0) and multiple detector-row (four-channel) helical CT (detector width, 1. 25, 2.5, 3.75, and 5 mm; pitch, 0.75 or 1.5). The SD of radius measurements along the rod (SD(r)) was used to quantify artifacts in all 72 data sets and to analyze their frequency patterns. Volume-rendered images of the data sets were ranked by six independent and blinded readers; findings were correlated with acquisition parameters and SD(r) measurements. RESULTS: SD(r) was smaller in four- than in single-channel helical CT for any given table increment (TI). In single-channel helical CT, SD(r) increased linearly with beam width and geometrically with pitch. In four-channel helical CT, SD(r) measurements were directly proportional to the TI, regardless of the detector width and pitch combination used. Off-center object position on average increased SD(r) by a factor of 1.6 for single-channel helical CT and by a factor of 2.0 for four-channel helical CT. Subjective rankings of image quality correlated excellently with SD(r) (Spearman r = 0.94, P <.001). CONCLUSION: Artifacts are quantitatively and subjectively smaller with four- compared with single-channel helical CT for any given TI.

Artifacts↗
PubMed1996

Activation of heat shock factor 1 DNA binding precedes stress-induced serine phosphorylation. Evidence for a multistep pathway of regulation.

Exposure of mammalian cells in culture to the anti-inflammatory drugs sodium salicylate or indomethacin results in activation of heat shock factor 1 (HSF1) DNA binding activity. We have previously shown that the drug-induced HSF1 becomes associated with the heat shock elements of the hsp70 promoter, yet transcription of the hsp70 gene is not induced (Jurivich, D. A., Sistonen, L., Kroes, R. A., and Morimoto, R. I. (1992) Science 255, 1243-1245). In this study, we have examined the basis for uncoupling the heat shock transcriptional response. Comparison of heat shock and drug-induced forms of HSF1 has revealed that the transcriptionally inert drug-induced HSF1 is constitutively but not inducibly serine-phosphorylated, whereas heat shock-induced HSF1 is both constitutively and inducibly serine-phosphorylated. The transcriptionally inert intermediate represented by drug-induced HSF1 can be converted to the transcriptionally active state by a subsequent exposure to heat shock. The only detectable change in HSF1 is the acquisition of inducible serine phosphorylation. These data reveal that acquisition of the trimeric DNA binding state of HSF1 is independent of and precedes inducible phosphorylation and furthermore that inducible phosphorylation correlates with transcriptional activation.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2005

Validation and application of single breath-hold cine cardiac MR for ventricular function assessment in children with congenital heart disease at rest and during adenosine stress.

PURPOSE: To validate the accuracy of ventricular function analysis using a single breath-hold real-time steady sate free precession (SSFP) cine MR method and demonstrate its application during adenosine stress imaging in children with congenital heart disease. MATERIALS AND METHODS: Twenty-eight subjects with congenital heart disease were studied (mean age 12.4 +/- 2.3 years) with MR imaging at 1.5 T. Short-axis images covering the entirety of both ventricles were acquired at rest, with a conventional segmented SSFP cine sequence acquired over multiple breath-holds and a single breath-hold real-time SSFP sequence. Seventeen subjects were given an infusion of adenosine, and the single breath-hold real-time short-axis stack was repeated during stress. Two independent observers performed the ventricular function analysis. Data was compared between the 2 acquisition methods at rest and between the single breath-hold acquisition at rest and during adenosine stress. RESULTS: There was good agreement between the multiple breath-hold and single breath-hold methods for measurement of end-diastolic volume (r = 0.95 and 0.96, p < .0001) and end-systolic volume (ESV) (r = 0.76 and 0.90, p < .0001) for the left and right ventricles respectively, and the left ventricular mass (r = 0.97, p < .0001). Adenosine was administered safely to all subjects. During stress there were significant changes in the heart rate and ESV, which led to a significant increase in cardiac output (mean 1.5 +/- 1.0 L/min, p < .001). CONCLUSION: Single breath-hold real-time SSFP cine imaging is robust and accurate in assessing cardiac function in children with congenital heart disease. An application of this method is the rapid assessment of cardiac function during adenosine stress.

Adenosine↗
PubMed1999

Risk factors for nosocomial bloodstream infections due to Acinetobacter baumannii: a case-control study of adult burn patients.

Risk factors for Acinetobacter baumannii bloodstream infection (BSI) were studied in patients with severe thermal injury in a burn intensive care unit where A. baumannii was endemic. Of 367 patients hospitalized for severe thermal injury during the study period, 29 patients with nosocomial A. baumannii BSI were identified (attack rate, 7.9%). Cases were compared with 58 matched controls without A. baumannii BSI. The overall mortality rate was 31% among cases and 14% among controls; only two deaths (7%) were considered directly related to A. baumannii BSI. Molecular typing of A. baumannii blood isolates by means of randomly amplified polymorphic DNA analysis and pulsed-field gel electrophoresis revealed the presence of three different strain types. Multivariate analysis showed that female gender (P = .027), total body surface area burn of > 50% (P = .016), prior nosocomial colonization with A. baumannii at a distant site (P = .0002), and use of hydrotherapy (P = .037) were independently associated with the acquisition of A. baumannii BSI in burn patients. These data underscore the need for effective infection control measures for this emerging nosocomial problem.

Acinetobacter↗
PubMed1993

HIV infection and Norwegian general practitioners: does fear affect knowledge?

The objective was to study the dimensionality of knowledge among general practitioners in Norway about transmission of HIV and what factors influence the degree of knowledge. Data were collected by a mailed questionnaire. Independent variables were experience of HIV, acquisition of knowledge and confidence in information on HIV from the central authorities and perception of own knowledge, skills of practice and fear of oneself or one's family contracting the HIV infection. Analysis of variance and multiple classification analysis were applied to measure the effect of independent variables on knowledge about transmission of HIV. The general practitioners in three counties (Oslo, Møre og Romsdal and Troms), constituting one-quarter of the Norwegian general practitioner population were selected (n = 578). The response rate was 65%, and the results are assumed to be representative of Norwegian general practitioners. Four dimensions of knowledge about transmission of HIV were identified by factor analysis. The two most important, transmission through 'body fluids' and transmission by 'needle sticks', were subsequently converted into sum scores and used as dependent variables. Forty-five per cent of the respondents were uncertain about ways in which HIV is not transmitted through 'body fluids'. There was an association between knowledge about transmission through 'body fluids' and the variables county background, confidence in the information about HIV and fear of contracting HIV. In the multiple classification analysis these three variables explained 11% of the variation in knowledge about transmission through 'body fluids'. Only confidence and fear significantly predicted the degree of knowledge, and among the 11% who had no confidence in the information received the effect of fear on knowledge increased significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

Attitude of Health Personnel↗
PubMed1989

Frequency measurements in real-time US equipment: variations from expected values.

The frequency responses of nine real-time mechanical probes and two pulsed Doppler probes from four manufacturers were measured. The reflected frequency was measured in a clinical environment by evaluating the pulser, transducer assembly, and receiver as a system. Two independent systems were used for these measurements: a spectrum analyzer and a data acquisition system that computed the fast Fourier transform of the reflected waveform. Results showed that probe frequency (calibrated by the manufacturer in the transmit mode with a hydrophone) was as much as 30% higher than that found by means of frequency measurement procedures with the probe attached to the ultrasound system and evaluated in the receive mode. Such large discrepancies indicate that if acceptance testing of the frequency spectrum is not performed at a clinical facility, prolonged clinical evaluation of new equipment should be arranged.

Ultrasonics↗
PubMed1989

Preloading history influences pressure-volume-derived indices of myocardial contractility in the ejecting canine left ventricle.

The dependency of indices of myocardial contractility on the immediate preloading protocol was assessed in 14 pentobarbital anesthetized open-chest dogs. An intracavitary micromanometer and epicardially placed ultrasonic dimension transducers allowed acquisition of dynamic left ventricular pressure-volume relationships while varying preload on right heart bypass. A resting cardiac output of 75 ml/kg/min was either increased twofold or reduced to zero flow over a 20-second interval. Linear regression analysis of the mechanical parameters permitted construction of the end-systolic pressure-volume relationship, rate of pressure rise-end-diastolic volume relationship, and the preload recruitable stroke work relationship. The slopes of the end-systolic pressure-volume relationship and rate of pressure rate-end-diastolic volume relationship were significantly higher when measured during volume depletion than during volume expansion (17.2 +/- 1.3 versus 8.5 +/- 0.8 mm Hg/ml and 205 +/- 14 versus 126 +/- 11 mm Hg/sec/ml, p less than 0.001, respectively). This finding was also evident when data analysis was confined to the initial 10 seconds of the loading interval. Nonlinear regression analysis of pooled data from both preloading protocols revealed curvilinear characteristics for each relationship. In contrast, the slope of the preload recruitable stroke work relationship was lower as a result of volume unloading (16.8 +/- 2.0 versus 22.8 +/- 1.7 mJ/beat/100 gm left ventricle/ml, p less than 0.01) and was independent of loading protocol when data analysis was confined to the initial 10-second acquisition period. Furthermore, second-order regression analysis of the pooled data showed no curvilinearity. These findings emphasize the importance of both the timing and method of varying cardiac preload in the determination of intrinsic myocardial contractility and suggest that the preload recruitable stroke work relationship may be a more linear contractile index that is less affected by preloading history over brief intervals.

Animals↗
PubMed2006

Spectral reconstruction methods in fast NMR: reduced dimensionality, random sampling and maximum entropy.

The need to reduce data acquisition times of multidimensional NMR experiments has fostered considerable interest in novel data acquisition schemes. A recurring theme is that of reduced dimensionality experiments, in which time evolutions in the indirect dimensions are incremented together, rather than independently. Spectral analysis of such data is carried out using methods such as filtered back-projection, GFT, or parametric signal modeling. By using Maximum Entropy reconstruction of reduced-dimensionality data, we show that the artifacts that arise in reduced dimensionality experiments are intrinsic to the data sampling, and are not, in general, the result of the methods used to compute spectra. Our results illustrate that reduced dimensionality is a special case of non-uniform sampling in the time domain. We show that MaxEnt reconstruction yields more accurate spectra for reduced dimensionality data than back-projection reconstruction and that randomly choosing time increments based on an exponentially weighted distribution is more efficient, with fewer artifacts, than the systematic coupling of time increments used in most reduced dimensionality approaches.

Artifacts↗
PubMed1985

Autoxidation of catechol(amine)s.

The autoxidation of nine catecholamines and two catechols as a function of pH was studied. The reaction rate constants of the distinct charged particles, in which catechol(amine)s can appear, are proved to be independent of pH. Autoxidation appears to be a feasible system for the acquisition of data useful for structure (re)activity relationships.

Catechol O-Methyltransferase↗
PubMed1996

Quantification and improvement of the signal-to-noise ratio in a magnetic resonance image acquisition procedure.

A procedure is developed to quantify and improve the signal-to-noise ratio (SNR) of magnetic resonance images. The image SNR is quantified using the correlation function of two independent acquisitions of an image. To test the performance of the quantification, SNR measurement data are fitted to theoretically expected curves. The proposed correlation technique is also used to improve the SNR by estimating the amplitude of the signal spectrum. The technique is applied to a set of MR images, and its performance in terms of gain in SNR, contrast-to-noise ratio (CNR), and resolution loss is compared to that of classical noise filters. The SNR as well as the CNR is improved significantly with minor loss of resolution. Finally, it is shown that the correlation technique can be implemented in a highly efficient way in almost any acquisition procedure of a magnetic resonance imaging system.

Image Processing, Computer-Assisted↗
PubMed1999

Can computer autoacquisition of medical information meet the needs of the future? A feasibility study in direct computation of the fine grained electronic medical record.

The project describes feasibility testing of a two-year clinical deployment of an electronic record keeping system for primary care medicine that allowed financial medical management and clinical disease study without the encumbrance of human encoding. The software used an expert system for acquisition of historical information and automatic database encoding of each independent fact. The historical acquisition system was combined with a screen-based physician data entry system to create a fine-grained medical record. Fine-grained data allowed direct computer processing to mimic the ends that presently require human encoding--gatekeeping, disease characterization and remote disease surveillance. The project demonstrated the possibility of real time gatekeeping through direct analysis of data. Detection and characterization of disease states using statistical methods within the database was possible, however, limited in this study because of the large numbers of patient interviews required. The possibilities for remote disease monitoring and clinical studies are also discussed.

Chi-Square Distribution↗
PubMed2006

Cardiac CINE MR imaging with a 32-channel cardiac coil and parallel imaging: impact of acceleration factors on image quality and volumetric accuracy.

PURPOSE: To assess the impact of parallel imaging algorithms on image quality and volumetric accuracy of CINE magnetic resonance imaging (MRI) with high temporal and spatial resolution using a new 32-channel dedicated cardiac phased array coil. MATERIALS AND METHODS: Fourteen individuals underwent steady-state free precession (SSFP) CINE MRI using a 32-element phased-array coil and parallel imaging acceleration using spatiotemporal sensitivity encoding (TSENSE). Acquisition acceleration ranged from R = 2 to 7. In conjunction with data extracted from phantom measurements, contrast-to-noise ratio (CNR) performance was evaluated for each acceleration factor and subjective image quality was evaluated by two independent readers. In addition, volumetric assessment was performed for each acceleration factor based on a single breath-hold multi-slice data acquisition. Results were compared to nonTSENSE measurements. RESULTS: CNR for non-accelerated CINE (R = 1) was 45.7 +/- 12.8 and showed a constant decrease with increase in acceleration of 51% at R = 4 and 86% at R = 7. CNR losses accompanied reductions in subjective image quality. Volumetric evaluation was accurate for R <or= 4, with significant underestimation of ejection fraction (EF) at higher accelerations. CONCLUSION: This study shows that one-dimensional acceleration factors up to R = 4 allow accurate SSFP CINE MRI even though CNR is significantly reduced. This allows for a marked reduction in scan time and allows for multi-slice CINE imaging with high spatial and temporal resolution.

Adult↗
PubMed1977

Establishing walking by severely retarded children.

This article examines the implications of independent ambulation for severely retarded children and reviews the literature describing behavioral interventions which facilitate walking. Findings from applied behavior analysis of single subjects support the value of operant techniques in the acquisition of walking. An operationally defined, data-based, four-level sequence for training walking beginning with momentary standing and ending with independent walking on command is described. Representative data from five severely retarded children are presented.

Behavior Therapy↗
PubMed2006

Time-sharing evolution and sensitivity enhancements in 2D HSQC-TOCSY and HSQMBC experiments.

Modifications of time-shared (TS) HSQC-like experiments originally developed by Griesinger and co-workers (Sattler M, Maurer M, Schleucher J, Griesinger C. J. Biomol. NMR 1995; 5: 97) are proposed to extract different types of information from a single NMR pulse scheme. It is shown that simultaneous acquisition of 1H,13C and 1H,15N HSQC-TOCSY and HSQMBC experiments can afford experimental sensitivity enhancements of 20-40% with respect to the separate acquisition of individual 13C or 15N data. In addition, the incorporation of a number of independent editing elements can be easily used for different purposes, for instance, to assign unambiguously 1H, 13C, and 15N chemical shifts, to differentiate directly from relayed cross-peaks, or to measure simultaneously long-range proton-carbon and proton-nitrogen coupling constants. The suggested methodologies can be applied to many different classes of nitrogen-containing compounds and illustrative examples are provided for the peptide cyclosporine as a demonstration of the performance of such experiments.

Journal Article↗
PubMed1999

Surgical treatment and risk of sporadic Creutzfeldt-Jakob disease: a case-control study.

BACKGROUND: Apart from the small number of iatrogenic and familial cases, the cause of most cases of Creutzfeldt-Jakob disease (CJD) is not known. We aimed to identify risk factors for sporadic CJD. METHODS: In a case-control study, we compared the medical history and selected demographic characteristics of 241 definite (neuropathologically confirmed) and probable (clinically likely) patients with CJD, ascertained from the Australian National Creutzfeldt-Jakob Disease Registry between Jan 1, 1970, and October 31, 1997, and of 784 controls, recruited from the community by random telephone interview in August, 1997. Standard logistic regression was used for the comparisons. FINDINGS: Surgical procedures were significantly associated with the development of sporadic CJD. This risk progressively increased with the number of surgical treatments to a maximum for three procedures (odds ratio 2.13 [95% Cl 1.34-3.41], p=0.002). There was also a significant association between risk of CJD and residence or employment on a farm (p<0.001) or market garden (p=0.002) for longer than 10 years. We found no significant risk associated with a history of blood transfusion, organ transplantation, major dental work, or occupation. INTERPRETATION: Our findings accord with the hypothesis that a range of surgical treatments may serve as unrecognised contamination events and account for a proportion of cases of sporadic CJD. Possible biases in different methods and times for the acquisition of data on cases and controls suggest our findings need to be replicated in independent studies with community controls.

Adolescent↗
PubMed1994

Development of behaviour in a young aye-aye (Daubentonia madagascariensis) in captivity.

This paper provides descriptive and quantitative information on the development of a young aye-aye in captivity during its first 10 months of life. The mother's behaviour was observed to provide an adult standard against which to evaluate the young male's development. Early development of the young aye-aye (including early vocalizations, locomotion and manipulation, acquisition of independence from the mother, threat/defence and alarm) is described in qualitative terms. Quantitative data on a number of other behaviours were collected using focal-animal sampling. Overall, this study indicated that the young aye-aye is relatively poorly developed during the 2-month nest phase but shows rapid development in comparison to other primates once it has left the nest.

Animals↗