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PubMed1998

Heart rate changes preceding ventricular ectopy in patients with ventricular tachycardia caused by reentry, triggered activity, and automaticity.

OBJECTIVES: Although enhanced sympathetic tone is thought to be proarrhythmic and beta-blockade reduces the risk of sudden cardiac death in survivors of myocardial infarction, the role of the autonomic nervous system in triggering spontaneous ventricular ectopy and ventricular tachycardia (VT) has not been fully elucidated. The purpose of this study was to compare and contrast autonomic tone preceding spontaneous ventricular arrhythmias in patients with reentrant, triggered, and automatic forms of VT. BACKGROUND: The prevailing model of reentrant VT is based on a triggering beat interacting with a fixed substrate. Within this model, cyclic fluctuations in autonomic tone comprise a "third factor" that may initiate the triggering extrasystoles as well as alter the substrate, facilitating perpetuation of tachycardia. Consistent with this model, adrenergic stimulation can facilitate the induction of reentrant arrhythmias as well as arrhythmias resulting from enhanced automaticity and those caused by triggered activity resulting from cyclic adenosine monophosphate-dependent delayed afterdepolarizations. METHODS AND RESULTS: On the basis of the results at electrophysiologic study, 26 patients with coronary artery disease were identified as having reentrant VT, 11 were identified as having idiopathic VT caused by triggered activity, and 4 were identified as having idiopathic VT caused by enhanced automaticity. Each patient underwent 24-hour electrocardiographic monitoring, and the mean sinus R-R intervals immediately preceding each sinus beat as well as the 15 beats preceding sinus beats, premature ventricular contractions (VPCs), and complex ventricular ectopy (couplet/non-sustained VT) were computed. In addition, high-frequency heart rate variability was determined. Heart rate accelerated before spontaneous ventricular ectopy for all three arrhythmia mechanisms. R-R intervals preceding episodes of complex ventricular ectopy were significantly shorter than the corresponding intervals preceding single VPCs in patients with 'riggered VT [p=0.006 and 0.01, R-R(-1) and R-R(-15), respectively] and in those with reentrant VT (p=0.007 and p=0.05). There were no corresponding differences in high-frequency heart rate variability. R-R intervals preceding single VPCs were significantly shorter than the corresponding intervals preceding sinus beats in patients with automatic VT (p=0.0004 and 0.0001, respectively), which was accompanied by a small reduction in high-frequency heart rate variability (p=0.04). CONCLUSIONS: Heart rate accelerates before spontaneous ventricular ectopy in patients with VT. The acceleration is disproportionate to parasympathetic withdrawal, implicating increased endogenous sympathetic tone in the genesis of spontaneous ventricular arrhythmias caused by all three electrophysiologic mechanisms: reentry, triggered activity, and automaticity.

Adolescent↗
PubMed2003

Automatic activation of the semantic network in schizophrenia: evidence from event-related brain potentials.

BACKGROUND: Language disorder associated with schizophrenia might be due to disturbances in both automatic activation and mechanisms of controlled attention. The contribution of each process to semantic memory dysfunction has not been determined for schizophrenia, and the semantic priming paradigm is well-suited for addressing this question. In the present report, event-related potentials (ERPs) elicited under conditions assumed to reveal automatic activation (short prime-target interval and low proportion of related words) are compared directly with ERPs elicited under conditions associated with controlled processing (long prime-target interval and high proportion of related words). METHODS: Visual ERPs were recorded during a lexical decision task, in which semantic relationship (associated and unassociated words), expectancy (relatedness proportions), and prime-target interval (250- and 850-msec inter-stimulus intervals [ISIs]) were varied. Diagnosis and expectancy were between-subjects factors; semantic relationship and ISI were repeated measures. The N400 priming effect (enhanced negativity to unassociated words) was compared between 34 male normal control subjects tested once and 37 male schizophrenia inpatients evaluated during their participation in a double-blind haloperidol maintenance therapy and placebo replacement protocol. RESULTS: The N400 priming effect for patients was significantly reduced during both pharmacologic phases, compared with controls. During haloperidol treatment, however, patients showed a significant N400 priming effect over the anterior scalp region and additionally under the automatic activation condition. The N400 priming effect was enhanced under the controlled processing condition for control subjects; this effect was not observed for patients. N400 amplitude elicited under the rapid presentation rate (250-msec ISI) differed between medicated patients and controls; groups did not differ for the 850-msec ISI. CONCLUSIONS: Findings suggest that automatic activation and mechanisms of controlled attention are both disrupted during semantic memory access for schizophrenia patients. Pharmacologic agents, such as haloperidol, might enhance automatic activation of the semantic network in this patient population, as indexed by the N400 component of the ERP.

Adult↗
PubMed2000

Automatic quantification of liver fibrosis: design and validation of a new image analysis method: comparison with semi-quantitative indexes of fibrosis.

BACKGROUND/AIMS: Liver fibrosis is one of the most important and characteristic histologic alterations in progressive and chronic liver diseases. Thus, in both clinical and experimental practice, it is fundamental to have a reliable and objective method for its precise quantification. Several semi-quantitative scoring systems have been described. All are time-consuming and produce partially subjective fibrosis evaluations that are not very precise. This paper describes the design and validation of an original image analysis-based application, FibroQuant, for automatically and rapidly quantifying perisinusoidal, perivenular and portal-periportal and septal fibrosis and portal-periportal and septal morphology in liver histologic specimens. METHODS: The implemented image-processing algorithms automatically segment interstitial fibrosis areas, while extraction of portal-periportal and septal region is carried out with an automatic algorithm and a simple interactive step. For validation, all automatically extracted areas were also manually segmented and quantified. RESULTS: Statistical analysis showed significant intra- and interoperator variability in manual segmentation of all areas. Automatic quantifications did not significantly differ from mean manual evaluations of the same areas. Comparison of our image analysis quantifications with staging histologic evaluations of liver fibrosis showed significant correlations (Spearman's, 0.72<r<0.83; p<0.0001) and that the latter are based more on the distribution patterns than on the quantity of fibrosis. CONCLUSIONS: FibroQuant is a sensitive, precise, objective and reproducible method of fibrosis quantification, which complements semi-quantitative histologic evaluation systems. This novel tool could be of special value in clinical trials and for improving the prognosis and follow-up among patients with fibrosis-inducing hepatic diseases.

Algorithms↗
PubMed1993

The use of the automatic core biopsy system in percutaneous renal biopsies: a comparative study.

We describe our experience with the use of the automatic core biopsy system for percutaneous renal biopsy and compare this with our experience with a standard biopsy needle. Three hundred twenty-three biopsies were performed between June 1983 and January 1993. From June 1983 through October 1990, 232 biopsies were performed with the use of a standard biopsy needle (Tru-cut needle; Travenol Laboratories, Deerfield, IL) and from November 1990 through January 1993, 91 biopsies were conducted with the use of the automatic core biopsy system (Biopty gun and needle; C.R. Bard, Inc, Covington, GA). Biopsies performed prior to January 1990 were reviewed retrospectively, while those performed after January 1990 were reviewed in a prospective manner. The primary indications for renal biopsy were to evaluate proteinuria (48.9%) and renal manifestations of systemic lupus erythematosus (26.0%). The two groups of patients were similar with respect to sex, age, serum creatinine, and coagulation parameters. Material for light microscopy, immunofluorescence microscopy, and electron microscopy was obtained in 98.9%, 98.9%, and 97.8% of cases, respectively, with the use of the automatic core biopsy system, and these values did not differ significantly from those with the use of the standard needle (99.6%, 96.1%, and 97.8%). Significantly more glomeruli were obtained by light microscopy per biopsy specimen with the use of the automatic core biopsy system versus the standard needle (28 +/- 15 and 21 +/- 13, respectively; P < 0.0001). Complications were assessed and separated by severity. Total complications were observed in 13 patients (14.3%) with the automatic core device and in 31 patients (13.4%) with the standard needle.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed2003

[Comparison between automatic and manual analysis in the diagnosis of obstructive sleep apnea-hypopnea syndrome].

OBJECTIVE: To compare automatic and manual analysis of neurological and respiratory variables obtained with the SomnoStar alpha 4100, a 16-channel polysomnographic system. PATIENTS AND METHOD: Twenty-eight patients suspected of obstructive sleep apnea-hypopnea syndrome were enrolled and given conventional polysomnographic tests. The order of automatic and manual reading of respiratory episodes, sleep stages, and arousals was randomized. We assessed agreement with the intraclass correlation coefficient and plotted standardized differences against standardized means, using the Bland-Altman method. RESULTS: Poor agreement was observed between the 2 types of analysis of sleep stages, especially for REM and deep sleep stages. Agreement was good for apneic episodes among the respiratory variables; however, automatic analysis underestimated hypopneas. If manual analysis is considered the gold standard at the apnea-hypopnea index cut point greater than 10, automatic analysis obtained a sensitivity of 55%, a specificity and positive predictive value of 100%, a negative predictive value of 47%, and an overall diagnostic yield of 67.8%. CONCLUSIONS: The automatic analysis of the SomnoStar 4100 system provides an unsatisfactory reading of sleep stages and respiratory episodes, especially hypopneas.

Female↗
PubMed2002

Should ward nurses be using automatic external defibrillators as first responders to improve the outcome from cardiac arrest? A systematic review of the primary research.

INTRODUCTION: The outcome from in-hospital cardiac arrest has improved little since the implementation of cardiopulmonary resuscitation 40 years ago. Early defibrillation improves survival following ventricular fibrillation and pulseless ventricular tachycardia. The emergence of automatic external defibrillators and advisory defibrillators has been heralded as the answer to defibrillation delays in-hospital. AIM: To locate and evaluate the evidence supporting automatic external defibrillator use in-hospital on general wards. METHOD: A systematic review of indexed and grey literature to identify primary research. RESULTS: Fifteen in-hospital automatic external defibrillator studies were located, five met the inclusion criteria. CONCLUSIONS: There is limited primary research evaluating automatic external defibrillators in-hospital. Manual defibrillators remain the most commonly used device for in-hospital defibrillation. Automated external defibrillators offer an alternative to manual defibrillation providing they have a screen and manual override capability, and the technology for pacing is close to hand. For in-hospital automatic external defibrillator programmes to be effective a change in nursing philosophy must occur, and defibrillation must become an expected rather than an extended nursing role.

Cardiopulmonary Resuscitation↗
PubMed1998

Automatic computerized radiographic identification of cephalometric landmarks.

Computerized cephalometric analysis currently requires manual identification of landmark locations. This process is time-consuming and limited in accuracy. The purpose of this study was to develop and test a novel method for automatic computer identification of cephalometric landmarks. Spatial spectroscopy (SS) is a computerized method that identifies image structure on the basis of a convolution of the image with a set of filters followed by a decision method using statistical pattern recognition techniques. By this method, characteristic features are used to recognize anatomic structures. This study compared manual identification on a computer monitor and the SS automatic method for landmark identification on minimum resolution images (0.16 cm2 per pixel). Minimum resolution (defined as the lowest resolution at which a cephalometric structure could be identified) was used to reduce computational time and memory requirements during this development stage of the SS method. Fifteen landmarks were selected on a set of 14 test images. The results showed no statistical difference (p > 0.05) in mean landmark identification errors between manual identification on the computer display and automatic identification using SS. We conclude that SS shows potential for the automatic detection of landmarks, which is an important step in the development of a completely automatic cephalometric analysis.

Adolescent↗
PubMed1996

Endothelial cell seeding improves patency of synthetic vascular grafts: manual versus automatized method.

Lack of an endothelial surface is the most important variable causing the relatively poor patency of synthetic bypass grafts. This study was designed to investigate the effect of endothelial cell seeding on small-diameter Dacron grafts seeded with microvascular endothelial cells from omentum, and to evaluate two methods (manual vs automatized) for one-stage seeding in a canine carotid artery model. In 30 mongrel dogs microvascular endothelial cells were harvested from omentum, either by a manual or an automatized method, and seeded onto 6-mm internal diameter Dacron prostheses prior to the graft interposition into the common carotid arteries. Non-seeded Dacron grafts were used as control grafts. All dogs received dipyridamole (75 mg/day) and acetylsalicylic acid (325 mg/day) for 4 weeks. The prostheses were explanted between 2 and 26 weeks after insertion. The results were assessed by patency, angiography, light and scanning electron microscopy, transmission electron microscopy, and morphometry. Endothelial cell seeding improved the patency rate significantly, regardless of the seeding methods used. The overall actuarial patency rates at 5, 12, and 26 weeks were 98%, 94% and 94%, respectively, for the seeded Dacron grafts, and 92%, 62% and 54%, respectively, for the non-seeded grafts. The automatized method yielded more endothelial cells per gram of omental tissue than the manual method (P = 0.0002), but there was no difference (P = 0.34) between the seeding densities per square centimeter of the graft surface. The harvesting and seeding by the automatized method took 55 min for the whole procedure, 20 min less than the manual method. We concluded that one-stage endothelial cell seeding with omental microvascular endothelial cells improved the patency of small-diameter Dacron grafts in a canine model. The automatized method obtained excellent results comparable to the manual procedure, and also reduced the time necessary for the cell seeding.

Animals↗
PubMed1989

Automatic application of teat disinfectant through the milking machine cluster.

An automatic device, which infuses disinfectant into the mouthpiece of the liner of the milking machine cluster as teatcups are removed, is described. Application at this time avoids any delay in disinfection, reduces the workload in the parlour and increases reliability of application. The teats of 20 cows were contaminated before each milking by immersion in a suspension of Staphylococcus aureus and Streptococcus agalactiae and then disinfected manually or automatically with iodophor after milking. Str. agalactiae was recovered from less than 5% of swabs and there was no difference between the results from the two methods. Neither method of disinfection was as effective against Staph. aureus and the recovery rate was significantly greater for the automatic method for both swabs from teat barrel (P less than 0.05) and teat apex (P less than 0.001). Rates of intramammary infection for quarters automatically or manually disinfected were similar and low (3/40 v. 6/40 respectively). The automatic method facilitates cluster removal by relieving vacuum and decreasing frictional contact at the mouthpiece lip, and utilizes approximately half the quantity of disinfectant used by manual dipping (0.9 v. 1.9 ml/teat). However, iodine contamination in the milk from the iodophor teat disinfectant was significantly increased from 14.4 to 102.2 micrograms 12/100 ml milk when no backflushing was practised.

Administration, Topical↗
PubMed1985

Event-related potentials elicited by automatic targets: a dual-task analysis.

The role of limited capacity processes in the detection of automatic targets was investigated in a dual-task paradigm using both behavioral and event-related brain potential (ERP) measures. An automatic detection task was paired with another concurrent discrimination while the relative importance of each task was systematically varied. The resulting performance operating characteristic (POC) showed that both the speed and accuracy of automatic detection responses were affected by the allocation of attention. Reductions in the accuracy of each task were accompanied by reductions in the amplitude of a late-positive component of the ERP (P300). In addition, the latency of the P300 component elicited by automatic targets was increased in dual-task conditions. A comparison of behavioral and ERP measures suggested the involvement of two separate limited-capacity processes in automatic detection: one concerned with the formation of an episodic representation of target occurrence and the other with the execution of rapid motor responses.

Attention↗
PubMed1990

An analysis of memory-based theories of automaticity.

Memory-based theories of automaticity predict that performance in a memory search task which is automatic will not require a representation of the memory set in working memory. The information contained in working memory was manipulated by inserting an interference task between the presentation of a memory set and a probe stimulus in a memory search task. The interference task prevented rehearsal, necessitating the retrieval of the memory set from long-term memory in variably mapped (VM) conditions. Performance in consistently mapped (CM) conditions provided strong support for memory-based theories of automaticity. With CM practice, both the effects of memory load and the effect of the interference task were eliminated. Furthermore, there was a temporal coupling in the reduction of these two effects with consistent practice. Monte Carlo simulations of memory-based automaticity predict such a temporal coupling. Automaticity is viewed as a continuum reflecting the relative contribution of the direct memory access of past solutions from long-term memory on performance.

Adolescent↗
PubMed1997

Exemplar similarity and the development of automaticity.

Effects of exemplar similarity on the development of automaticity were investigated with a task in which participants judged the numerosity of random patterns of between 6 and 11 dots. After several days of training, response times were the same at all levels of numerosity, signaling the development of automaticity. In Experiment 1, response times to new patterns were a function of their similarity to old patterns. In Experiment 2, responses to patterns with high within-category similarity became automatized more quickly than responses to patterns with low within-category similarity. In Experiment 3, responses to patterns with high between-category similarity became automatized more slowly than responses to patterns with low between-category similarity. A new theory, the exemplar-based random walk (EBRW) model, was used to explain the results. Combining elements of G. D. Logan's (1988) instance theory of automaticity and R. M. Nosofsky's (1986) generalized context model of categorization, the theory embeds a dynamic similarity-based memory retrieval mechanism within a competitive random walk decision process.

Adult↗
PubMed1997

Automatic process development following severe closed head injury.

Automatic process development was investigated in a closed head injury (CHI) population. Ten severe CHI participants (> 1 year postinjury) and 10 matched controls completed consistent mapping (CM) and varied mapping (VM) semantic-category memory search tasks. In VM search, despite a similar pattern of serial memory search, the CHI participants responded slower than controls and exhibited slower memory search rates throughout practice (1,800 trials). In CM search, after extensive practice (1,800 trials) both groups showed the performance characteristics indicative of automatic process development, that is, near-zero slopes and large reductions in response times. However, the CHI participants were slower to automatize the task. These results indicate that for memory-based search tasks the effects of a CHI may slow down the speed with which automatic processes develop but that CHI participants can acquire and use automatic processes in task performance.

Adult↗
PubMed2000

Effects of divided attention on automatic and controlled components of memory after severe closed-head injury.

The relation between attention available at encoding and automatic and consciously controlled aspects of memory was investigated using the process-dissociation procedure. Twenty-four severely closed-head injured (CHI) participants (> 1 year postinjury) and 24 matched controls studied word lists in full- and divided-attention conditions. Recall cued with word stems was tested. In contrast to consciously controlled memory, the CHI group did not perform more poorly than the controls in estimates of automatic memory. Furthermore, for both groups, the divided-attention manipulation reduced the controlled estimates of memory, whereas automatic influences remained invariant. These results suggest that automatic memory processes may remain partially immune to the deleterious effects of severe CHI or show recovery by 1 year postinjury. They also indicate that automatic memory processes do not require additional attentional resources following severe CHI.

Adult↗
PubMed1999

Automatic quantification of microvessel density in urinary bladder carcinoma.

Seventy-three TUR-T biopsies from bladder carcinoma were evaluated regarding microvessel density, defined as microvessel number (nMVD) and cross-section endothelial cell area (aMVD). A semi-automatic and a newly developed, automatic image analysis technique were applied in immunostainings, performed according to an optimized staining protocol. In 12 cases a comparison of biopsy material and the corresponding cystectomy specimen were tested, showing a good correlation in 11 of 12 cases (92%). The techniques proved reproducible for both nMVD and aMVD quantifications related to total tumour area. However, the automatic method was dependent on high immunostaining quality. Simultaneous, semi-automatic quantification of microvessels, stroma and epithelial fraction resulted in a decreased reproducibility. Quantification in ten images, selected in a descending order of MVD by subjective visual judgement, showed a poor observer capacity to estimate and rank MVD. Based on our results we propose quantification of MVD related to one tissue compartment. When staining quality is of high standard, automatic quantification is applicable, which facilitates quantification of multiple areas and thus, should minimize selection variability.

Humans↗
PubMed2002

Usefulness of automatic detection of fragmented red cells using a hematology analyzer for diagnosis of thrombotic microangiopathy.

We previously reported an automatic method for quantitative analysis of schistocytes or fragmented red cells using an automatic hematology analyzer, XE-2100. In the study reported here, we evaluated the accuracy of this detection method in patients with thrombotic microangiopathy (TMA). A follow-up study was performed on 14 patients with two types of TMA, thrombotic thrombocytopenic purpura or hemolytic uremic syndrome. Schistocyte percent was evaluated both with an automatic counter and by means of microscopic observation. Total activity and isoenzyme pattern of lactate dehydrogenase (LD) were also determined. In these patients, schistocyte percent determined by automatic counting correlated highly with that determined by manual counting under microscopic observation (r = 0.852, P < 0.0001). Schistocyte percent was shown to correlate significantly with isoenzyme fractions 1 and 2 of LD (r = 0.732, P < 0.02), reflecting hemolysis. Nine of 11 patients tested had high concentrations of LD isoenzyme five without distinct liver damage, and schistocyte percent did not relate to fraction 5 of LD. Automatic detection of schistocyte percent using a hematology analyzer was useful for an accurate diagnosis and follow-up of thrombotic microangiopathy. The origin of LD fraction 5 remains to be determined.

Adult↗
PubMed2001

[A software tool for automatic image-based ventilation analysis using dynamic chest CT-scanning in healthy and in ARDS lungs].

PURPOSE: Density measurements in dynamic CT image series of the lungs allow one to quantify ventilated, hyperinflated, and atelectatic pulmonary compartments with high temporal resolution. Fast automatic segmentation of lung parenchyma and a subsequent evaluation of it's respective density values are a prerequisite for any clinical application of this technique. MATERIAL AND METHODS: For automatic lung segmentation in thoracic CT scans, an algorithm was developed which uses (a) different density masks, and (b) anatomic knowledge to differentiate heart, diaphragm and chest wall from ventilated and atelectatic lung parenchyma. With Animal Care Committee approval, the automated technique was tested in 8 anaesthetized ventilated pigs undergoing dynamic CT before and after induction of lavage-ARDS. Images were acquired in one supradiaphragmatic, cross-sectional slice (temporal resolution of 100 ms; slice thickness of 1 mm, high resolution reconstruction algorithm). In 120 CT images the total pixel number and the calculated MLD from the automatically segmentated lung were compared to the values obtained from an interactive lung segmentation. RESULTS: The software tool was able to read all image series (DICOM standard). Automatic and interactive segmentation were in high agreement (R(2) = 0.99 for the total number of pixels and the MLD). Originally, the most frequent error was misclassification of atelectasis as extrapulmonary solid tissue. CONCLUSION: An automatic software tool is presented for lung segmentation in healthy lungs and in ARDS. Aerated lung and atelectasis were identified with high accuracy. This post-processing tool allows for a quantitative, CT based assessment of ventilation and recruitment processes in the lung. Thus, it may help to optimize ventilation patterns in patients with ARDS.

Animals↗
PubMed1996

Recovery of automatic and cognitive functions in traumatic brain injury using the functional independence measure.

Automatic tasks are performed with minimal attentional guidance. Neural pathways subserving attention are often impaired in traumatic brain injury (TBI). Therefore, the process of automatization is crucial in skill development, due to the fact that it allows attention to be directed towards the more abstruse components of task [1]. Automatic and cognitive categories were created by aggregating three of the motor items and three of the cognitive items respectively of the Functional Independence Measure (FIM). The averages of these categories were calculated for every evaluation of the FIM, and their relationship to each other was examined. Over a 9-month period 24 patients were selected from a TBI population with a major component of diffuse axonal injury (DAI). Eighty-eight per cent (n = 21) of the patients reached independence for the automatic category, but only 29% (v = 7) reached this level for the cognitive category. When independence was achieved, the average time to do so for the automatic category 6.7 weeks) was not significantly different from the time it took to reach cognitive independence (6.9 weeks). It was found that there were significant statistical differences in the scores between the two categories. Premorbid IQ had no effect on these categories. However, the rate which these two categories increased, from the time of admission to discharge, was not significantly different.

Activities of Daily Living↗