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At least 703 records · Page 39Linked to original sources
PubMed1994

New approach to automatic contour detection from image sequences: an application to ventriculographic images.

A procedure for detecting contours automatically is particularly needed when processing sequences of cardiographic images. In fact, in this field the number of images to be processed is, in general, large enough to make a manual tracing phase unacceptable. In this paper a new approach to automatic contour detection from image sequences is presented. If a rough contour of the desired structure is available on the first frame, every contour of the sequence is automatically outlined. The entire process is based on two main steps carried out in turn. First, an image is convolved with a mask of suitable size in order to transform any discontinuity, such as the boundary of the structure one is looking for, into a furrow of suitable width. Second, every point of a given starting contour, which is entirely contained inside the furrow, is made to fall to the bottom of the furrow by means of a localization algorithm.

Algorithms↗
PubMed2000

Dissociating automatic and intentional processes in children's eyewitness memory.

Two experiments investigated the contribution of automatic and intentional memory processes to 5- and 8-year-old children's acceptance of misinformation. Children were presented with a picture story followed by misleading postevent details that either were read to participants or were self-generated in response to semantic and perceptual hints. Children were then given a recognition test under 2 instructional conditions. In the inclusion condition children reported whether they remembered items from either of the previous phases. In the exclusion condition children were instructed to exclude postevent suggestions. Children were more likely to accept misled-generate items compared to misled-read items in the inclusion condition, but the opposite was the case under exclusion instructions. Both automaticity and recollection (cf. L. L. Jacoby, 1991) influenced misinformation acceptance, but the role of automatic processes declined with age.

Age Factors↗
PubMed1995

Automatic analysis of protein conformational changes by multiple linkage clustering.

An automatic algorithm is presented for analyzing protein conformational changes such as those occurring upon substrate binding or in different crystal forms of the same protein. Using, as sole information, the atomic coordinates of a pair of protein structures, the procedure first generates structure alignments, which optimize the root-mean-square deviation of the backbone atoms. To this end, equivalent secondary structures and/or loops from both proteins are combined by a multiple linkage hierarchic clustering algorithm, which generates several intertwined clustering trees. Automatic analysis of these clustering trees is used to dissect the mechanism of the conformational change. It allows the identification of the static core, representing the collection of secondary structures which undergo no structural changes, as well as other entities which move like rigid bodies. It also permits the description of the movement of secondary structures or loops relative to this core or entities. USing this information, it can be inferred whether a particular conformational change involves shear or hinge motion, or components of both. The algorithm is applied to the analysis of the conformational changes of citrate synthase, lactate dehydrogenase, lactoferrin and beta-glucosyltransferase, representing typical examples of shear- and hinge-type mechanisms, and a varied range in movement size. The results are shown to be in excellent agreement with previous analyses, and to provide additional information which gives a more complete and objective picture of the conformational change. Using our automatic algorithm, we find that any conformational change may be viewed as having components of both shear- and hinge-type motion. Determining which of these is most appropriate requires the combination of the information provided by our procedure with detailed knowledge of the protein tertiary structures.

Algorithms↗
PubMed2005

Fully automatic kidneys detection in 2D CT images: a statistical approach.

In this paper, we focus on automatic kidneys detection in 2D abdominal computed tomography (CT) images. Identifying abdominal organs is one of the essential steps for visualization and for providing assistance in teaching, clinical training and diagnosis. It is also a key step in medical image retrieval application. However, due to gray levels similarities of adjacent organs, contrast media effect and relatively high variation of organ's positions and shapes, automatically identifying abdominal organs has always been a challenging task. In this paper, we present an original method, in a statistical framework, for fully automatic kidneys detection. It makes use of spatial and gray-levels prior models built using a set of training images. The method is tested on over 400 clinically acquired images and very promising results are obtained.

Adult↗
PubMed1979

Oculographic automatic perimetry in glaucoma visual field screening: a clinical study--preliminary results in glaucoma patients.

An automatic method for visual field screening using oculographic potentials have been evaluated on 12 eyes of 65 glaucoma patients. The oculographic perimeter records, plotting the central 22 degrees of the visual field, have been compared with Armaly's manual selective perimetry performed by the Goldman Perimeter. In spite of different testing standards of both methods, equivalent pathological field defects were demonstrated in 72% of the eyes following the first examination. Successive plottings with the automatic method improved the results considerably. The method has proved to be a reliable objective automatic test. Further development is suggested through which the procedure might be useful for glaucoma screening in the future.

Adolescent↗
PubMed1994

Involvement of alpha-adrenoceptors in the excitatory effect of the A2 adenosine receptors agonist 5'-N-ethylcarboxamidoadenosine (NECA) on cardiac automaticity in the isolated right ventricle of the rat.

The effects of the non-selective A2 adenosine receptor agonist 5'-N-ethyl-carboxamidoadenosine (NECA) were studied on ventricular automaticity induced by a local injury in the isolated right ventricle of the rat. In concentrations ranging from 0.1 to 100 nM, NECA significantly increased ventricular automaticity. This effect was not apparent when the nonselective alpha-adrenoceptor blocker phenoxybenzamine was present at a concentration of 10 microM, which antagonizes both alpha 1- and alpha 2-adrenoceptors, as well as when rats were pretreated with reserpine. In non-reserpinized rats, the excitatory effect of NECA was also abolished in the presence of the selective alpha 1-adrenoceptor antagonist prazosin, but not in the presence of the alpha 2-adrenoceptor antagonist idazoxan. In reserpinized rats, the excitatory effect of NECA was restored in the presence of the non specific alpha-adrenoceptor agonist phenylephrine as well as in the presence of the selective alpha 1-adrenoceptor agonist amidephrine but not in the presence of the selective alpha 2-adrenoceptor agonist clonidine. These results suggest that the excitatory effect of NECA on ectopic ventricular automaticity is dependent on endogenous catecholamines and that alpha-adrenoceptors of type 1 are, in some way, involved in this effect.

Adenosine↗
PubMed1986

Application of automatic image analysis for morphometric studies of peroxisomes stained cytochemically for catalase. I. Electron-microscopic application.

The feasibility of the application of an electronic image analyzer, the Texture Analysis System (TAS) (Leitz Wetzlar, FRG), for fast automatic ultrastructural morphometric studies of hepatic peroxisomes has been investigated. Rat liver peroxisomes were stained selectively with the alkaline DAB procedure for localization of catalase in order to obtain sufficient contrast for automatic detection by TAS. Electron micrographs of ultrathin sections from this material were analyzed both automatically by TAS and manually by using a digitizer tablet connected with an Apple IIe microcomputer. The results showed negligible differences. As far as the speed of the operation is concerned, the image analysis was 4-5 times faster than the manual technique. In further studies, the importance of using DAB-stained sections for accurate morphometric studies of peroxisomes was demonstrated by comparing the results of such DAB-stained preparations with unstained material. This revealed that the numerical density was lower and the average profile diameter higher in unstained sections. The value for volume density was also affected, being about 30% lower in such preparations. It is likely that in unstained preparations small peroxisomes without crystalline nucleoids were frequently not identified as such and were not taken into account in morphometric calculations. These observations establish that computer-controlled electronic image analysis in conjunction with selective cytochemical staining of peroxisomes for catalase provides a fast, accurate and reliable method for ultrastructural morphometric studies of this organelle in rat liver.

Animals↗
PubMed1987

The guinea-pig step cycle: X-ray cinematographic analysis of the forelimb during pharmacologically induced "stepping automatism".

"Stepping automatism" has generally been studied in mesencephalic or spinal cats and has been induced electrically with the animal on a treadmill (Shik and Orlovsky 1976). Derivatives of 4-R-2,2,5,5-tetrakis (trifluoromethyl)-imidazoline (SIS = Substances capable of Inducing Stepping) I-IV (Liu 1985, Liu et al. 1984) can induce regular "stepping automatism" in guinea pigs. The present paper concerns the guinea-pig step cycle of the forelimb during SIS II-induced "stepping automatism" analysed with the use of X-ray cinematography and electromyography (EMG) studies in suspended animals. Results show that the flexion phase (F E1) and the extension phase (E2 E3) of the SIS-induced step cycle are quite comparable to those of the normal step cycle in other quadrupedal animals walking on the ground. The excursions of elbow, shoulder and scapula joints are all in phase in F and E3, whereas the scapula is largely out of phase with the elbow and shoulder during E1 and E2. It is surprising that during SIS II-induced locomotion in guinea pigs suspended in the air, "yield" could be seen in both, the elbow and the shoulder joints.

Animals↗
PubMed1991

Semi-automatic quantitation of dense markers in cytochemistry.

The quantitation of electron dense labelling is very tedious when it is done "by hand". Accordingly we developed software allowing, at electron microscopic level, a semi-automatic counting of dense markers in biological specimens. It includes the digitization of images and extraction of dense particles from the grey level of the background. The definition of the areas of interest was carried out by the observer but all quantitative calculations were done automatically. This method was applied to different biological materials (phospholipid and lysozyme labelling in secretory granules of human submucosal bronchial gland cells). The results obtained by this semi-automatic procedure were in good agreement with those obtained by manual counting of colloidal gold labelling (r = 0.97).

Automation↗
PubMed1978

Automatic computerized perimetry in the detection of neurological visual field defects. A pilot study.

Forty-seven eyes from 25 patients with neurological disease were examined with an automatic computerized perimeter primarily intended for glaucoma. Manual kinetic and static perimetry with Goldmann's instrument was used for comparison. In 32 fields, the automatic method disclosed all defects that had been found by manual perimetry. Furthermore, it detected three small defects that had been missed in the initial manual examination. The remaining 12 fields were normally using both methods. Consequently, in detecting field defects, the automatic perimeter was superior to the manual method.

Amblyopia↗
PubMed1989

An automatic analysis method for in situ hybridization using high-resolution image analysis.

Specific mRNA for alpha 1 (I) collagen has been detected on a cellular level by in situ hybridization using radioactively labelled alpha 1 (I) antisense RNA probes. We here present an automatic, quantitative, evaluation technique for the determination of grain densities using the high-resolution image analysis system IPS KONTRON. The reliability and objectivity of this method were evaluated by comparing the values of grains per cell obtained by conventional and automatic techniques following in situ hybridization with alpha 1 (I) collagen DNA probes in various specimens. The correlation coefficients between conventional and automatic analysis of grain densities were 0.97 for fibroblasts embedded into a three-dimensional collagen gel, 0.94 for dermal fibroblasts in skin obtained from a patient with progressive systemic scleroderma, and 0.90 for fibroblasts in a 2-week-old scar. All correlation coefficients were significant on the P less than 0.0001 level. This new analysis technique therefore allows a more rapid and reliable quantitative evaluation of in situ hybridization and may also be helpful in differentiating between various cell populations characterized by different biosynthetic capacities.

Autoradiography↗
PubMed1980

A prospective study of the effects of the progestagen content of oral contraceptives on measures of affect, automatization, and perceptual restructuring ability.

Thirty-five young women completed the Profile of Mood States and tests of automatization and perceptual restructuring ability before and after commencing one of three forms or oral contraception (OC) or one form of intrauterine contraception (the loop). For each subject on each experimental variable the difference between the first and second tests was computed. These data were then analysed by covariance and discriminant function analyses. Two sets of functions were derived. The first distinguished the loop users from the OC users. The latter exhibited significantly greater increases in anger and significantly greater reductions in vigor than the former. The second set of discriminant functions distinguished users of Neogynon from the women in the other three groups. Neogynon users' performances on the Color Words Test (a measure of automatization ability) worsened and their anger, vigor and tension scores had decreased to a greater extent than was the case for members of the other groups. It is suggested that the changes in affect demonstrated by the first discriminant function were related to personal and attitudinal variables associated with the Loop users. The second discriminant function was interpreted as an indication that the varying progestagen content of OC may have differential effects upon both affect and automatization ability.

Contraceptives, Oral↗
PubMed1992

Evaluation of antifungal activity of antimycotics by automatic analyzing system.

Antifungal activity of several antimycotics has been evaluated using an automatic analyzing system (AAS), which is composed of a specially designed reaction vessel, microscopic observation system, image analyzing system, and computer program for automatic tracing of hypha growth. The agar plate was prepared on the ceiling of the reaction vessel, and spore mass of a fungus (Aspergillus niger) was inoculated onto it. After the preincubation at 28 degrees C for 24 h the reaction vessel was set on a microscope stage and connected to the liquid flow system. An appropriate hypha was selected for the measurement of growth process during the following steps: first contact with saline for 30 min for the adaptation, the second contact with same saline for 30 min, contact with saline containing an antimycotic substance for 60 min, and contact with flushing saline for 60 min. During a sequence of these steps, the apical tip of a growing hypha displayed on a TV monitor was followed automatically. The dynamic response of hypha to an agent was analyzed by several parameters. Morphological changes of the hypha caused by respective agents were recorded on VTR for further analysis. By using this system, the antifungal activity of antimycotics could be quantitatively determined within several hours.

Amphotericin B↗
PubMed1984

Differential effects of Bay k 8644, a presumed calcium channel activator, on sinoatrial nodal and ventricular automaticity of the dog heart.

Bay k 8644 is suggested to increase calcium influx through the voltage-dependent calcium channel. In isolated, blood-perfused sinoatrial node preparations of the dog. Bay k 8644 injected intra-arterially increased sinus rate as isoprenaline did. In isolated, blood-perfused papillary muscle preparations of the dog isoprenaline injected intra-arterially increased both the force of contraction of the papillary muscle and its spontaneous beating rate. In these preparations, however, Bay k 8644 failed to increase the beating rate, although it increased the force of contraction. These results are consistent with the concept that the slow inward current plays a role in sinoatrial nodal automaticity but not in automaticity of Purkinje fibres which was reflected as ventricular automaticity of the papillary muscle preparations used here.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1994

Technical aspects of automatic micronucleus analysis in rodent bone marrow assays.

The mouse bone marrow micronucleus assay is an in vivo test commonly used in the pharmaceutical industry to evaluate the genotoxic potential of new compounds. The test detects agent-induced chromosomal damage or damage of the mitotic spindle apparatus. In this paper the state-of-the-art in automated rodent micronucleus evaluation using computerized image analysis in combination with high-quality slides obtained by the cellulose column fractionation technique is reviewed. The latter allows the effective removal of nucleated cells from rodent bone marrow. It has been found that automatic micronucleus scoring with the Leitz MIAC image analyzer is substantially faster than labor-intensive manual analysis. Automatic scoring can be performed overnight for up to 16 slides. We have been successfully using automatic micronucleus analysis for the testing of new pharmaceutical drugs for more than 3 years.

Animals↗
PubMed1993

Anterior opercular cortex lesions cause dissociated lower cranial nerve palsies and anarthria but no aphasia: Foix-Chavany-Marie syndrome and "automatic voluntary dissociation" revisited.

Anarthria and bilateral central facio-linguovelo-pharyngeo-masticatory paralysis with "automatic voluntary dissociation" are the clinical hallmarks of Foix-Chavany-Marie syndrome (FCMS), the corticosubcortial type of suprabulbar palsy. A literature review of 62 FCMS reports allowed the differentiation of five clinical types of FCMS: (a) the classical and most common form associated with cerebrovascular disease, (b) a subacute form caused by central nervous system infections, (c) a developmental form probably most often related to neuronal migration disorders, (d) a reversible form in children with epilepsy, and (e) a rare type associated with neurodegenerative disorders. Bilateral opercular lesions were confirmed in 31 of 41 patients who had CT or MRI performed, and by necropsy in 7 of 10 patients. FCMS could be attributed to unilateral lesions in 2 patients. The typical presentation and differential diagnosis of FCMS provide important clues to lesion localization in clinical neurology. FCMS is a paretic and not an apraxic disorder and is not characterized by language disturbances. Its clinical features prove divergent corticobulbar pathways for voluntary and automatic motor control of craniofacial muscles. Precise clinico-neuroradiological correlations should facilitate the identification of the structural substrate of "automatic voluntary dissociation" in FCMS.

Aphasia↗
PubMed1994

Automatic selection of tidal volume, respiratory frequency and minute ventilation in intubated ICU patients as start up procedure for closed-loop controlled ventilation.

OBJECTIVE: Before a patient can be connected to a mechanical ventilator, the controls of the apparatus need to be set up appropriately. Today, this is done by the intensive care professional. With the advent of closed loop controlled mechanical ventilation, methods will be needed to select appropriate start up settings automatically. The objective of our study was to test such a computerized method which could eventually be used as a start-up procedure (first 5-10 minutes of ventilation) for closed-loop controlled ventilation. DESIGN: Prospective Study. SETTINGS: ICU's in two adult and one children's hospital. PATIENTS: 25 critically ill adult patients (age > or = 15 y) and 17 critically ill children selected at random were studied. INTERVENTIONS: To stimulate 'initial connection', the patients were disconnected from their ventilator and transiently connected to a modified Hamilton AMADEUS ventilator for maximally one minute. During that time they were ventilated with a fixed and standardized breath pattern (Test Breaths) based on pressure controlled synchronized intermittent mandatory ventilation (PCSIMV). MEASUREMENTS AND MAIN RESULTS: Measurements of airway flow, airway pressure and instantaneous CO2 concentration using a mainstream CO2 analyzer were made at the mouth during application of the Test-Breaths. Test-Breaths were analyzed in terms of tidal volume, expiratory time constant and series dead space. Using this data an initial ventilation pattern consisting of respiratory frequency and tidal volume was calculated. This ventilation pattern was compared to the one measured prior to the onset of the study using a two-tailed paired t-test. Additionally, it was compared to a conventional method for setting up ventilators. The computer-proposed ventilation pattern did not differ significantly from the actual pattern (p > 0.05), while the conventional method did. However the scatter was large and in 6 cases deviations in the minute ventilation of more than 50% were observed. CONCLUSIONS: The analysis of standardized Test Breaths allows automatic determination of an initial ventilation pattern for intubated ICU patients. While this pattern does not seem to be superior to the one chosen by the conventional method, it is derived fully automatically and without need for manual patient data entry such as weight or height. This makes the method potentially useful as a start up procedure for closed-loop controlled ventilation.

Adolescent↗
PubMed1992

A widely unappreciated cause of failure of an automatic noninvasive blood pressure monitor.

Many anesthesiologists have come to depend on automatic noninvasive blood pressure monitoring to obtain blood pressure (BP) readings. A case is presented in which, during a critical phase of the anesthetic, an automatic noninvasive blood pressure (ANIBP) device not only failed to provide meaningful clinical data but, in fact, gave an error message that was misleading. At the time of the message, the patient was noted to be in ventricular trigeminy at a rate of 92 beats/min. It appears that the repetitive beat-to-beat fall in blood pressure due to the dysrhythmia "fooled" the automatic noninvasive blood pressure device's software algorithm into believing that there was an air leak in the system. Thus, in addition to pointing out an unappreciated and potentially troubling device-related critical event, the present case demonstrates the importance of good human factors design for medical devices used in the critical care setting. In particular, the issue is raised of how medical devices should deal with uncertain or potentially misleading data.

Aged↗