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PubMed1976

Neurophysiology of locomotor automatism.

It had long been known that the decapitated cock can cross a yard. During the last century an automatic mechanism controlling stepping movements has also been found in other vertebrates. The system controlling locomotion has many features similar to these systems controlling other natural movements: respiration (28), micturition (98), scratching (154), mastication (33), etc. Today we know that there are spinal automatisms for each limb generating its stepping movements. Activity of these automatisms depends essentially on the afferent inflow from the moving limbs. There also is interaction of the limbs during locomotion that promotes their coordination. The existence of two descending systems with different functions in the control of locomotion (Fig. 1) also can be considered as an established fact. Activity of a number of neurons involved in the control of locomotion has been studied directly during locomotion in decorticate, thalamic, and mesencephalic cats. To explain the experimental data at hand, several hypotheses of organization of the spinal automatism of stepping have been forwarded: a chain-reflex hypothesis, a hypothesis of two reciprocal half-centers, and a ring hypothesis (Fig. 2). Although general features of the system controlling locomotion are more or less clear, many questions are not yet answered. It is unknown what relative contributions to motoneuronal activity are made by proprioceptive reflexes versus influences from the automatism of stepping. Furthermore the structure of the spinal stepping automatism is not known. It is not clear if the spinal stepping automatisms of the forelimbs are as potent as those of the hindlimbs. The descending system responsible for activation of the spinal automatism of stepping has not yet been identified in direct experiments. The inputs and outputs of the subthalamic and midbrain "locomotor" regions have not been found, and we know almost nothing about intrinsic interaction of neurons in these regions. The role of inhibitory thalamic influences is scarcely known. Finally, we have no data concerning the influence of either cortical (42, 186) or visual mechanisms in locomotor control.

Afferent Pathways↗

PubMed2006

Application accuracy of automatic registration in frameless stereotaxy.

OBJECTIVE: We compared the application accuracy of an infrared-based neuronavigation system when used with a novel automatic registration with its application accuracy when standard fiducial-based registration is performed. METHODS: The automatic referencing tool is based on markers that are integrated in the headrest holder we routinely use in our intraoperative magnetic resonance imaging (MRI) setting and can be detected by the navigation software automatically. For navigation targeting we used a Plexiglas phantom with 32 notched rods of different heights. The phantom was fixed in the head holder and multiple optimized gradient echo slices containing the clamp-integrated markers were acquired. After that we measured a T1 MPRAGE sequence with a slice thickness of 1.0 mm for navigation. The deepest points of the surface of the rods were defined as target points in image space. In three measurement series we referenced the phantom once with 4, once with 7 fiducials and twice automatically. In one series we performed only one automatic registration. The localization error was measured 3 times per rod and registration. RESULTS: The median localization errors for standard registration with 7 fiducials were between 1.2 and 3.05 mm. With 4 fiducials, medians were in the range from 1.87 to 2.21 mm. For the automatic registration we obtained median localization errors between 0.88 and 2.13 mm. In 6 of the 8 samples that were compared the automatic registration showed an application accuracy that was highly significantly better (p < 0.001 in most cases) than that of fiducial-based standard registration. CONCLUSION: The application accuracy found for automatic referencing is at least not worse than that for standard registration no matter whether 4 or 7 fiducial markers were used. Therefore, its use in the operating room is feasible. In combination with intraoperative MRI it may become a favorable alternative to standard fiducial-based registration especially when an intraoperative update of navigation data is necessary.

Automation↗

PubMed1988

Role of a pertussis toxin-sensitive protein in the modulation of canine Purkinje fiber automaticity.

We previously have shown that alpha-adrenergic stimulation of canine Purkinje fibers and rat ventricle decreases automaticity. Experiments on rat ventricular myocytes in tissue culture have suggested that the decrease in automaticity induced by alpha-adrenergic stimulation depends on the development of sympathetic innervation and the presence of a pertussis toxin-sensitive, 41-kDa guanosine triphosphate (GTP)-regulatory protein. In the present study, microelectrode and biochemical techniques were used to test the role of the pertussis toxin-sensitive protein and sympathetic innervation in modulating automaticity of adult canine Purkinje fibers. Fibers were incubated in Tyrode's solution alone or in Tyrode's solution plus pertussis toxin (0.1-0.5 microgram/ml) for 24 hours and were then superfused with phenylephrine. Phenylephrine in the 5 x 10(-9)-5 x 10(-8) M range induced a decrease in automaticity in 63% of the 16 fibers not treated with pertussis toxin and an increase in automaticity in 37%. The former group had a higher level of pertussis toxin-sensitive substrate by the [32P]nicotinamide adenine dinucleotide adenosine diphosphate (ADP)-ribosylation assay than the latter. In contrast, all fibers treated with pertussis toxin (0.5 microgram/ml) showed increased automaticity in response to phenylephrine and had no detectable pertussis toxin-sensitive substrate. Over the range of pertussis toxin concentrations studied, there was a smooth concentration-response relation between the substrate levels measured and the automatic response to phenylephrine. As ADP-ribosylatable substrate levels decreased, the percent of fibers showing an increase in automaticity increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Diphosphate Ribose↗

PubMed2001

HCV-RNA detection in liver bioptates--a comparison of automatic and 'home-made' protocols combined with a new procedure of HCV-RNA extraction.

BACKGROUND: For HCV-RNA detection in liver tissue a generally accepted reference method has not been established yet. Therefore, we have developed a procedure of HCV-RNA extraction from liver tissue and compared two methods of HCV-RNA detection. MATERIALS AND METHODS: A set of 32 liver biopsy specimens, obtained from chronically HCV infected patients, has been examined. At the time of biopsy, serum HCV-RNA was detectable in 20 patients in RT-PCR automatic Cobas AmplicorTM Hepatitis C assay, ver. 2.0 (Roche Molecular Systems, Inc, Pleasanton, CA, USA) 2 serum samples were negative for HCV-RNA and 10 patients has not been tested. Liver tissue has been homogenized in the presence of CRSR-Green (Fast RNA Kit-Green, Bio101, Inc, Vista, CA, USA) and a mixture of phenol/chloroform/isoamylic alcohol, using a FastPrep homogenizator (Bio101, Inc, Vista, CA, USA). Then RNA has been isolated from the material obtained using the Total RNA Prep Plus procedure (A&A Biotechnology, Gdańsk, Poland). Presence of HCV-RNA was next tested by means either of 'home-made' nested RT-PCR procedure or the RT-PCR automatic Cobas AmplicorTM Hepatitis C assay, ver. 2.0. In case of an inhibition of PCR detected in the first run of automatic assay, both PCR procedures have been repeated. RESULTS: In 5 cases of automatic assay an inhibition of PCR reaction has been detected in the first run, the RT-PCR procedures has been then successfully repeated in the second run. The presence of HCV-RNA in the liver tissues was detected in a total of 22 cases (69%) by mean of automatic assay and in a total of 20 cases (63%) by means of 'home-made' RT-PCR procedure. Except for two cases of HCV-RNA positivity in a biopsy tissue, detected by means of automatic but not 'home-made' procedure, the results obtained employing the methods have been identical. In one serum HCV-RNA positive case, the presence of HCV RNA has not been detected in a liver tissue using both methods. CONCLUSIONS: Our procedure of RNA isolation combined either with automatic Cobas AmplicorTM Hepatitis C assay, ver. 2.0 or 'home-made' RT-PCR procedure may be useful for establishing presence of HCV-RNA in liver tissue. In this combination, the automatic assay seems to be more sensitive than the 'home-made' procedure.

Biopsy↗

PubMed2005

[Usefulness and practical use of an automatic counter for scattering pollen in spring].

BACKGROUND: In this decade some automatic pollen counters have been developed and showed them useful in some reports. However, the results of automatic counting have not been established. METHOD: We have compared scattering cedar and cypress pollen counts with Durham pollen samplers and a newly developed automatic pollen counter (KH-3000) in the spring from 2000 to 2004 in Tokyo. RESULTS: The relationship between the data of the automatic counter and that of a Durham sampler method is so good that this automatic counter seems useful. The best relationship between two methods was seen from late February to early April in the season of high amounts of pollens scatters. The ratio of pollen counts measured with automatic counter and Durham sampler was about 3.5 on average in the period of enough cedar and cypress pollen dispersion. The avoidance of pollens seems possible with real-time pollen information because reliability of automatic counting is highly evaluated when enough pollens scatter. CONCLUSION: In future, the standardization of automatic counting should be necessary for the accurate evaluation of scattering pollens.

Air Pollutants↗

PubMed1990

[Possibilities and limitations of the automatic analysis of sleep stages using the Oxford system].

34 ambulatory polygraphic sleep-records of young adults were carried out using the Oxford Medilog 9000 recorder. All of the records underwent automatic evaluation by the Oxford Sleep Stager. 10 cases were, in addition, evaluated visually. 4 records could not be analyzed because of artifacts. Thus, 30 subjects were used in the end for establishing standard values of sleep parameters. Automatic versus automatic comparisons and automatic versus visual comparisons of ten polysomnograms were performed epoch-by-epoch. The automatic versus automatic comparison showed agreement in 85.5% of epochs, and the automatic versus visual comparison in 70.4% of epochs. The Sleep Stager showed the best agreement with the visual evaluation in epoch-by-epoch comparison in the REM-stage (93.9%), the worst in stage 1 (32.4%). In calculating the percentages of total night sleep for the respective sleep stages, the automatic analysis showed strongest disagreement with visual evaluation in the REM-stage (plus 7.5%) and in stage 2 (minus 5.2%).

Adult↗

PubMed1983

Antiarrhythmic effects of ethmozin in cardiac Purkinje fibers: suppression of automaticity and abolition of triggering.

The effects of ethmozin were studied on automatic and triggered impulse initiation in isolated canine cardiac Purkinje fibers using standard microelectrode technique. In driven Purkinje fibers with normal (greater than or equal to -80 mV) maximum diastolic potentials, ethmozin (2-4 mg/l or 4.3-8.6 muM) slightly increased the slope of phase 4 depolarization. However, the rate of normal automatic firing in such fibers was decreased by ethmozin and the threshold (take-off) potential of the pacemaker cells was shifted in the depolarizing direction (toward zero potential). In fibers treated with barium chloride (0.10-0.50 mM), "abnormal automaticity" occurred from maximum diastolic potentials of -38 to -68 MV. Ethmozin (2-4 mg/l) consistently slowed and abolished this abnormal automaticity. This appeared to be associated with a decrease in the rate of diastolic depolarization. When lidocaine, 4 or 10 mg/l (17 or 42 muM), was tested on abnormal automaticity induced by barium, it too was found to decrease the rate of diastolic depolarization and decrease the automatic rate. However, lidocaine never terminated barium-induced abnormal automaticity. Ethmozin also consistently abolished abnormal automaticity in Purkinje fibers taken from the endocardial surface of 24- or 48-h infarct zones. Finally, ethmozin (1-4 mg/l or 2.2-8.6 muM) depressed the amplitude of delayed after depolarizations and terminated triggered activity in Purkinje fibers taken from 24-hr infarct zones. Each of these actions could contribute to the antiarrhythmic effects of ethmozin.

Action Potentials↗

PubMed1995

Random zero sphygmomanometer versus automatic oscillometric blood pressure monitor; is either the instrument of choice?

The Hawksley random zero sphygmomanometer was designed to eliminate observer bias and two digit preference. We have measured blood pressure (BP) in a group of 62 young adults (median age 26.1 years, range 20.2-31.3 years) with reflux nephropathy under standardised conditions (that is, in the morning, after a 2 h supine rest, before venepuncture, using a standard 12 x 23 cm adult size cuff appropriate for the machine used) utilising the random zero sphygmomanometer and the automatic oscillometric BP monitor (Dinamap 8100, Critikon). Seven consecutive recordings of right brachial BP at intervals of 2 min were taken using each instrument alternatively, and the first reading was discarded. The first instrument used to measure BP was alternated between patients to eliminate bias on instrument preference. Random zero sphygmomanometer was used as recommended by the manufacturers and Korotkoff phase V was used to measure the DBP. The observer and the equipment used were the same throughout the study period. The mean SBP and DBP were calculated to the nearest 1 mm Hg utilising the three recordings taken by each instrument. The limits of agreement and the repeatability coefficients for each method of measurement were assessed utilising the statistical method described by Bland and Altman in 1986. The correlation coefficients among random zero and automatic oscillometric BP monitor for SBP and DBP measurements were 0.84 and 0.67, respectively. The average BP (mean of random zero and automatic oscillometric BP monitor measurement) plotted against the difference between the two methods of measurement showed no relation between the difference and the average of measurement in the ranges of BP studied, that is, between 100 and 160 mm Hg systolic and 55 and 100 mm Hg diastolic. The mean of difference between random zero and automatic oscillometric BP monitor for SBP was -6.45 (s.d. 6.07) and for DBP +10.77 (s.d. 8.16) mm Hg. The limit of agreement for SBP measurement was +5.69 to -18.59 mm Hg and for DBP was +27.09 to -5.55. The repeatability coefficients of random zero and automatic oscillometric BP monitor for systolic and diastolic measurements were 8.64 and 7.04, and 9.72 and 6.62, respectively. Bland and Altman analysis indicates major differences between the two methods of measurement. The automatic oscillometric BP monitor could on average over-read the systolic by 6.45 mm Hg and under-read the diastolic by 10.77 mm Hg compared with that of random zero. Furthermore, the limits of agreement were wide enough for a normotensive to be inadvertently defined as a hypertensive on machine error alone. This clearly indicates that automatic oscillometric BP monitor and random zero BP measurements cannot be used interchangeably in clinical practice. Furthermore, the repeatability coefficients, which should ideally be zero, are too large for either instrument to be considered as the gold standard for BP measurement, although that of automatic oscillometric BP monitor was superior to that of random zero. This study highlights the importance of using nomograms generated by the same method of measurement for comparison both in paediatric and adult practice for correct interpretation of BP.

Adult↗

PubMed1997

The effect of context and metamemory judgements on automatic processes in memory.

These experiments examine two aspects of the automatic influences on memory as measured by target responding in the exclusion condition within the process dissociation framework. In Experiment 1, we examine the extent to which congruency between study and test contexts affects automatic processes in memory. In Experiment 2, we investigate qualitative differences in consciously controlled and automatic processing as indexed by metamemory judgements. In both experiments, a process-dissociation procedure was used to separate automatic and consciously controlled uses of memory in a stem completion task. In the study phase of Experiment 1, subjects read a passage from one of two directed perspectives. The subsequent stem completion task, which subjects performed while mindful of the study perspective, contained (a) old words congruent with the directed perspective, (b) old words congruent with a different (non-directed) perspective, and (c) words that had not been presented. Estimates of automatic influences for words congruent with the directed perspective were found to be greater than estimates for words incongruent with the directed perspective. These results provide evidence for the automatic or unconscious influences of meaning on task performance, which is uncontaminated by the influence of consciously controlled recollection which may occur in indirect memory tests. In Experiment 2, judgements of learning made prior to retrieval under inclusion and exclusion instructions were found to be different for consciously controlled and automatic processes, suggesting that memory as measured by the opposition (exclusion) procedure is involuntary and unconscious, with prospective monitoring of performance not sensitive to eventual performance.

Automatism↗

PubMed2001

Social influence effects on automatic racial prejudice.

Although most research on the control of automatic prejudice has focused on the efficacy of deliberate attempts to suppress or correct for stereotyping, the reported experiments tested the hypothesis that automatic racial prejudice is subject to common social influence. In experiments involving actual interethnic contact, both tacit and expressed social influence reduced the expression of automatic prejudice, as assessed by two different measures of automatic attitudes. Moreover, the automatic social tuning effect depended on participant ethnicity. European Americans (but not Asian Americans) exhibited less automatic prejudice in the presence of a Black experimenter than a White experimenter (Experiments 2 and 4), although both groups exhibited reduced automatic prejudice when instructed to avoid prejudice (Experiment 3). Results are consistent with shared reality theory, which postulates that social regulation is central to social cognition.

Automatism↗

PubMed1981

Pacing-induced automaticity in sheep Purkinje fibers.

The induction and decay of pacing-induced automaticity were studied in 15 sheep Purkinje fiber preparations superfused with modified Tyrode's solution containing norepinephrine, 2.5 x 10(-7) M. All preparations were quiescent prior to pacing. Spontaneous automaticity could be induced in each preparation provided a sufficient number of pacing stimuli were applied at a fast enough rate. Once the minimum pacing requirements for induction of automaticity were exceeded, the number, total duration, and fastest rate of the induced beats were proportional to the number and rate of the pacing stimuli up to a maximum which could not be exceeded. Consecutive trains of stimuli were additive in inducing automaticity, provided that the pauses between them were short enough to preclude the time-dependent return of automatic properties to their pre-pacing level. Prolonged sequence of fixed pacing trains resulted in stable degrees of automaticity which depended on the length of the pause between them. These observations permit a semiquantitative description of induced automatic behavior and help establish a model that may be useful in future studies.

Action Potentials↗

PubMed1993

Checklist procedures and the cost of automaticity.

Automaticity is usually discussed in terms of its benefits. Automaticity has, however, a cost that manifests itself in procedures that are highly routinized but require close attention, such as verbal checklist procedures. In such procedures, errors occur because the routine leads to automaticity. In three paper-and-pen experiments, we tested this manifestation and investigated ways to decrease automaticity in verbal checklist procedures. In the experiments, subjects proofread sets of multiplication problems to detect erroneous operations, simulating the checklist procedure. In Experiments 1 and 2, two conditions were compared: a fixed-order condition (in which each set contained operations in the same order) and a varied-order condition (in which the operations were in a different order in each set). In Experiment 1, proofreading times were measured to establish the role of fixed sequential order as a consistent environment promoting the emergence of automaticity. In Experiment 2, we introduced errors into the material, and in Experiment 3 we introduced "alerting" conditions to interfere with the development of automaticity. The results indicated that the subjects in the varied-order and alert conditions detected significantly more errors than did those in the fixed-order condition. The implications of the findings for current theories of automaticity are discussed as well as those for the design of checklist procedures.

Adult↗

PubMed2000

[Ictal automatisms during partial complex seizures in 36 children].

Partial complex seizures are relatively frequent type of epileptic seizures. These attacks are having aura in 60% of cases, that can be vegetative, motor, sensor or psychological one. Important is aura in the form of uncinatus seizures (unpleasant odor), because we must exclude tumor of temporal region in these patients. Altered consciousness comes after aura, patient has opened eyes, face can be pale or red, and automatism appear, in the form of different movements. These automatisms are often considered insignificant by parents or eyewitnesses. There is often misdiagnosis of this type of seizures, because only about 20% of standard EEG recordings find specific epileptic grapho-elements. Therapy of these seizures is difficult, with the success in only 50% of cases. Ictal automatisms were tested in the group of 36 children with partial complex seizures aged 4 to 17 years. Duration of epilepsy was 1 to 5 years. All patients had proved diagnosis of partial complex seizures, clinically and on electroencephalography, CT scan and MRI in medically intractable seizures. Eleven patients were videotaped during the attack. All patients had questionnaire filled by parents, about automatisms. Thirty-four patients (94.4%) had ictal automatisms, and 2 with epileptic focus in frontal region did not. Some patients had different types of automatisms. Most frequent ones were mimicking (15.19%), sitting-standing up (10.76%), swinging (8.23%), swallowing (7.59%) etc. It can be concluded that automatisms are almost obligatory part of partial complex seizure, and their registration is essential for correct diagnosis and treatment of these seizures.

Adolescent↗

PubMed1997

Automatisms in non common law countries.

The distinction made in the common law tradition between sane and insane automatisms, and in particular the labelling of epileptic automatisms as insane, are legal concepts which surprise and even astonish lawyers of other traditions, whether they work within a civil law system or one with elements both from civil law and common law. It could be useful to those lawyers, doctors and patients struggling for a change in the common law countries to receive comparative material from other countries. Thus, the way automatisms are dealt with in non-common law countries will be discussed with an emphasis on the Norwegian criminal law system. In Norway no distinction is made between sane and insane automatisms and the plea Not Guilty by virtue of epileptic automatism is both available and valid assuming certain conditions are met. No. 44 of the Penal Code states that acts committed while the perpetrator is unconscious are not punishable. Automatisms are regarded as "relative unconsciousness", and thus included under No. 44. Exceptions may be made if the automatism is a result of self-inflicted intoxication following the consumption of alcohol or (illegal) drugs. Also, the role and relevance of experts as well as the law of some other European countries will be briefly discussed.

Automatism↗

PubMed1980

Automatic perimetry (COMPETER). Ability to detect early glaucomatous field defects.

The ability of fully automatic computerized perimetry to detect early glaucomatous field damage was compared with that of careful static and kinetic manual perimetry in a clinical study on 104 patients, 51 of whom had early glaucomatous field defects, 20 of whom were glaucoma suspects with no field defects, and 33 of whom were normal. The automatic perimeter used was the COMPETER automatic perimeter employing actual threshold measurements. The interpretation of the automatic fields followed a set of predetermined criteria. Fifty-one eyes had defects in the manual charts, 48 (94%) of which were detected by automatic perimetry using the central test point pattern of the perimeter. Two (4%) fields thought to be normal after manual perimetry were correctly found to be abnormal by the automatic perimeter, which yielded four (8%) false-positives in the normal fields. By using a different set of criteria for the interpretation of the automatic fields, the sensitivity could be increased to 98% of these early defects, but at the cost of 22% false-positives.

Adult↗

PubMed2004

Automatic quantification of gene amplification in clinical samples by IQ-FISH.

BACKGROUND: The reliable detection and quantification of gene amplifications is crucial to clinical practice. Although there are different detection techniques, the fluorescence in situ hybridization (FISH) method has become highly accepted over past years because it is a reliable, robust, and quick method. Unfortunately, automatic quantification of gene amplification based on fluorescence intensities has not been possible thus far. Because current spot counting methods are reliable only when analyzing low amplification rates, we attempted to establish another method, i.e., to quantify the intensity of different FISH signals using an automatic fluorescence microscopical device on interphase nuclei: interphase quantitative FISH (IQ-FISH). METHODS: We quantified the fluorescence intensities of the differently labeled FISH probes (MYCN and D2Z) hybridized to three different neuroblastoma cell lines, six peripheral blood (PB) samples, 10 spiked PB samples, and nine neuroblastoma samples using the Metafer4 system (MetaSystems, Altlussheim, Germany). To obtain the MYCN copy number per cell, the ratio between the fluorescence intensities of the MYCN gene and reference sequence (D2Z) was calculated. For automatic analysis of the HER-2/neu status in tumor cells, labeled FISH probes specific for HER-2/neu and a chromosome 17-specific probe were hybridized to peripheral blood and tumor specimens and analyzed using the automatic device. RESULTS: When measuring the fluorescence intensity per cell for both probe pairs (MYCN/D2Z and HER-2/17p), amplified and non-amplified cells, showed distinct peaks with only little overlap. Whereas normal cells showed a fluorescence ratio peak for MYCN/D2Z between 200 and 800, cells with MYCN amplification clearly exceeded this ratio value (1000 to 25,000). When mixing a varying number of MYCN amplified cells (range 9-91%) to normal PB, the spiked tumor cells could be identified. Even one neuroblastoma tumor cell in 1000 mononucleated cells could reliably be detected using our device. In neuroblastoma patient samples, non-amplified cells were distinguished from amplified cells. Automatically and manually counted signals gave matching results in amplified and non-amplified samples. HER-2/neu-amplified cells were automatically detected in the breast cancer samples analyzed. CONCLUSION: The automatic measurement of fluorescence signal intensities not only allows a reliable discrimination between non-amplified and amplified cells but also exact quantification of amplified sequences. This is the prerequisite for the following applications: detection of amplified cells in the bone marrow and second-look specimens; comparison between primary and relapse or pre- and post-chemotherapeutic specimens; detection of tumors with focal gene amplification; and quantification of elimination of amplified gene sequences.

Automation↗

PubMed2005

Interactions between volitional and automatic breathing during respiratory apraxia.

The sites and forms of interactions between voluntary breathing acts and automatic respiratory rhythm generation are the subject of considerable research interest. We report here observations of the control of breathing in a patient suffering from an advanced form of progressive supranuclear palsy (Steele-Richardson-Olszewski syndrome). This patient demonstrated a severely compromised ability to perform volitional respiratory acts upon command, despite exacerbated behavioural and automatic control of respiration. The presence of residual volitional control of breathing in this patient provided interesting insights concerning the interaction between the automatic and the voluntary control of respiration. We observed that (1) when the subjects was asked to inspire voluntarily he could at best mobilize a volume similar to spontaneous VT and only very slowly; (2) automatic breathing movements persisted, superimposed onto the active voluntary movements, with an amplitude that decreased when the inspiratory activity, albeit weak, reached its maximal level; (3) during breath holding both the amplitude and the frequency of the basal spontaneous rhythmic activity were depressed. This observation therefore supports the idea of a strong interaction between volitional and automatic breathing in the form of an inhibition of automatic activity during voluntary breathing. Although, the site of interaction (spinal versus supraspinal) could not be determined during volitional inspiration, the effect of breath holding on the frequency of the spontaneous breathing activity supports the view that a volitional breathing arrest has some inhibitory effects on the respiratory oscillator at the medullary level. Finally, in an attempt to reconcile the persistence of a rhythmic activity during voluntary inspiration and expiration with previous data from the literature, it is proposed that the normal suppression of the automatic activity during voluntary inspiration relies on cortical and sub-cortical structures involved in the planning, i.e. the praxic component, of a respiratory task rather than on projections originating from the primary motor cortex.

Aged↗

PubMed1998

Agreement and reproducibility of automatic versus manual measurement of QT interval and QT dispersion.

To determine whether the automatic measurement of the QT interval is consistent with the manual measurement, this study evaluated the reproducibility and agreement of both methods in 70 normal subjects and 54 patients with hypertrophic cardiomyopathy. The mean, minimum, and maximum QT interval and QT dispersion were computed in a set of 6 consecutive electrocardiograms (3 in the supine and 3 in the standing position) obtained from each subject. The automatic method determined the T-wave end as the intersect of the least-squares-fit line around the tangent to the T-wave downslope with the isoelectric baseline. Manual measurements were obtained using a high-resolution digitizing board. QT dispersion was defined as the difference between the maximum and minimum QT interval and as standard deviations of the QT interval duration in all and precordial leads. In patients with hypertrophic cardiomyopathy, the absolute values of the QT interval and QT dispersion were significantly higher than those in normal subjects (p < 0.0001). In both groups, the intrasubject variability of the QT interval was significantly lower with automatic than with manual measurement (p < 0.05). The agreement between automatic and manual QT interval measurements was surprisingly poor, but it was better in patients with hypertrophic cardiomyopathy (r2 = 0.46 to 0.67) than in normal subjects (r2 = 0.10 to 0.25). In both groups, the reproducibility and agreement of both methods for QT dispersion were significantly poorer than for QT interval. Hence, the automatic QT interval measurements are more stable and reproducible than manual measurement, but the lack of agreement between manual and automatic measurement suggests that clinical experience gained with manual assessment cannot be applied blindly to data obtained from the automatic systems.

Adolescent↗