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PubMed1988

Two differential mechanisms of automaticity in diseased human atrial fibers.

The ionic mechanisms of automaticity in spontaneously active preparations (n = 38) from "diseased" human atria were investigated. The cycle length (CL) of the automatic action potential (AAP) ranged from 0.6 to 4.5 s (mean +/- S.D.: 2.0 +/- 1.0 s). The AAP from preparations obtained from non-digitalized patients (group 1, n = 29) showed various CLs, in that 16 patients had a CL longer than 2.0 s (slow-type AAP) while in tissues from the other 13 patients, the CL was 2.0 s or less (fast-type AAP). On the other hand, all preparations obtained from the digitalized patients prior to cardiac surgery (group 2, n = 9) had the fast-type AAP (CL less than or equal to 2.0 s). The slow-type AAP was accelerated and changed to the fast one after application of ouabain (1 microM) or by perfusing with 50% [Na+]o Tyrode solution. Ryanodine (1 microM), a specific inhibitor of calcium release from the sarcoplasmic reticulum (SR), markedly lengthened the CL of fast-type AAP, without affecting the slow-type AAP. In contrast, caffeine (15 mM) shortened the CL of the slow-type AAP and remarkably lengthened the CL of the fast-type AAP, as is the case in ryanodine. The rate of slow-type AAP was enhanced with an increase in [Ca2+]o and depressed with a decrease in [Ca2+]o or with application of diltiazem, a Ca2+ channel blocker. The slow-type AAP was changed to the fast-type AAP by stretching the preparation by about 20%. In vitro preparations excised from patients with dilated atria revealed a shorter CL of AAPs. We conclude that in "diseased" human atrial preparations, the ionic mechanism responsible for generation of slow- and fast-type automaticity differs. Slow automaticity (CL greater than 2.0 s) perhaps relates to activation of the slow inward Ca2+ current, while the fast-type automaticity (CL less than or equal to 2.0 s) is linked to cyclic increases in [Ca2+]i.

Action Potentials↗
PubMed1978

Modification and application of the computerized automatic audiometer.

Recently, medical information processing systems applying computers have achieved marked advances in parallel with the development of highly accurate automatic measuring instruments. The authors already in 1974 developed and reported a computerized automatic audiometer containing a micro-computer which stored a program for audiometric procedures. Subsequently the authors have developed a compact, multi-purpose audiometric instrument which executes the standard air-bone conduction audiometry, with the exclusion of masking, automatically with a built-in micro-computer. An outline of the instrument is as follows: 1. The instrument is composed of a memory, a control unit, programs for data processing and measurement, a character display for instructing subjects and an audiogram display. It can be operated manually in the same way as a conventional audiometer. 2. Test errors and any abnormally large differences between the responses of the two ears can be detected automatically, and the tests can then be re-executed manually after finishing the automatic procedure for correction of the data. 3. The instrument is provided with output terminals for connection to an external computer or other peripheral equipment. It is designed to be compact and light weight.

Adult↗
PubMed2002

Effects of automatic cluster remover settings on average milking duration, milk flow, and milk yield.

A crossover study design was used in five commercial dairy herds to study the effect of altering the switch point settings for automatic cluster remover units on the average duration of unit attachment, milk flow, and milk yield. Automatic cluster remover switch point settings were alternated, for 1-wk periods, between 0.50 and 0.64 kg/min (1.1 and 1.4 lb/min) in one herd and between 0.73 and 0.82 kg/min (1.6 and 1.8 lb/min) in the four remaining herds. Parlor data were captured at 329 separate milking sessions (range 39 to 92 per herd), representing 239,393 individual cow milkings. While increasing the automatic cluster remover switch point setting was not associated with a change in average milking duration in one herd, it had the effect of significantly reducing the average milking duration by between 10.2 and 15.6 s per cow in the remaining four herds. Milk flow was significantly increased at higher switch point settings for all five herds. Higher automatic cluster remover switch point settings did not have a negative effect on milk yield in any of the herds studied and, in fact, were associated with increased milk yield in two of the five herds. Decreasing milking duration while either maintaining or increasing the volume of milk harvested should ultimately lead to improved milking efficiency and parlor performance. Modifying systems to increase automatic cluster remover switch point settings offers an important potential opportunity to increase parlor efficiency in commercial dairy herds.

Animals↗
PubMed2004

Effects of an automatic postmilking teat dipping system on new intramammary infections and iodine in milk.

A technology of automatically applying a postmilking teat dip via the milking machine prior to machine detachment was compared to manual postmilking teat dipping with a teat dip cup for effects on new IMI and iodine content in milk. One hundred twenty Holstein cows were experimentally challenged in a 22-wk trial with Streptococcus agalactiae and Staphylococcus aureus and 148 Holstein cows were experimentally challenged with Streptococcus uberis in another 22-wk trial. The bacterial suspensions were applied to teats of all of the cows after premilking udder preparation and immediately prior to milking machine attachment. In both trials, cows were divided among four treatments: no postmilking teat dipping; manual postmilking teat dipping with a proven efficacious iodophor teat dip; manual postmilking teat dipping with an iodophor teat dip formulated for an automatic postmilking teat dipping system; and automatically postmilking teat dipping via milking machines with an iodophor teat dip formulated for the automatic postmilking teat dipping system. The postmilking teat dipping treatments reduced new Staph. aureus IMI by 64.5, 76.5, and 88.2%; new Strep. agalactiae IMI by 61.5, 77.8, and 94.4%; and new Strep. uberis IMI by 63.5, 82.5, and 93.8%, respectively, against the treatment of no postmilking teat dipping. The treatment applying the postmilking teat dip automatically via milking machines had the lowest number of new IMI caused by the three pathogens. Teat end and teat skin condition were characterized as normal at the end of the study with no differences between treatments. There were no differences with regard to iodine content in milk between treatments.

Animals↗
PubMed1991

Studies on coagulation and the development of an automatic computerized bipolar coagulator. Technical note.

A new computerized bipolar coagulator is described in which tissue heating is switched off automatically when adequate vessel occlusion has been achieved, thus preventing overheating, undue tissue damage, cutting, and sticking of the forceps. Experiments with radiofrequency (rf) heating of albumin or arteries revealed an impedance minimum at the moment of coagulation. The attainment of this impedance minimum is transmitted electronically via a microprocessor to the coagulator, which automatically shuts off the rf energy supply. In experiments, adequate artery strength and avoidance of the drawbacks of conventional coagulation methods were achieved when rf heating was shut off soon after the impedance minimum was reached. Neither irrigation for cooling nor cleaning of the forceps tips was necessary. Electronic feedback through the same cables as used for coagulation enabled the use of conventional bipolar cables and forceps. The bipolar coagulator described can also be used for conventional bipolar coagulation under visual control. The microcomputer enables: 1) automatic coagulation cycles that start when tissue is picked up in the forceps and stop automatically on completion of the seal; 2) the change of power setting from a pedal and activation of automatic cycles by the pedal as described above or surgeon-controlled coagulation, which facilitates the use of alternative debridement with inactive forceps; 3) cable testing; and 4) negligible disturbance of the intraoperative monitoring equipment.

Animals↗
PubMed2004

Between reality and imagination: when is spatial updating automatic?

Spatial updating has been shown to occur automatically and operate on both real and imagined environments. In three experiments, we compared spatial updating in real and imagined environments and examined when automatic spatial updating occurs. Participants learned the locations of real objects in a room and imagined being in their kitchens. They turned to face either the kitchen or the room targets and pointed to the targets before and after turning. Although objects in the real environment were automatically updated when the participants turned in the imagined environment, targets in the imagined environment were not automatically updated when the participants turned in the real environment. However, explicit spatial updating of imagined environments was as efficient as that of real environments. Automatic updating of the real objects required perceptual experience of these targets, either visually or by touch, and did not occur when the targets were described verbally. Implications for spatial cognition research are discussed.

Adolescent↗
PubMed1997

Efficacy of automatic continuous positive airway pressure therapy that uses an estimated required pressure in the treatment of the obstructive sleep apnea syndrome.

BACKGROUND: Continuous positive airway pressure (CPAP) is effective therapy for the obstructive sleep apnea syndrome (OSAS). Automatic CPAP devices continuously adjust the positive pressure to the required levels. OBJECTIVE: To determine the efficacy of an automatic CPAP machine used with an estimated reference pressure value. DESIGN: A before-and-after, single-blind trial in which patients were randomly allocated to one of three modes of CPAP administration. SETTING: Referral-based sleep center in a public health care institution. PATIENTS: 36 outpatients with OSAS. INTERVENTION: Continuous positive airway pressure was given at a conventional fixed pressure (group 1), automatic CPAP was given at a measured reference pressure (group 2), and automatic CPAP was given at an estimated reference pressure (group 3). In group 1, the effective pressure was determined during a titration sleep study. In groups 2 and 3, the pressure interval was allowed to vary from 4 cm H2O below reference pressure to 3 cm H2O above reference pressure. In group 3, the estimated value of the reference pressure was determined according to individual anthropometric characteristics. MEASUREMENTS: Sleep studies were performed and measurements of diurnal sleepiness were obtained at each visit. RESULTS: Sleep and breathing disorders and hypersomnolence were alleviated similarly in the three groups. The apnea + hypopnea index remained abnormal in one patient in group 3 for whom the reference pressure had been underestimated. A strong negative correlation was found between the percentage of time spent below reference pressure during CPAP and the difference between the effective and estimated pressures. CONCLUSION: Automatic CPAP can be used with an estimated reference pressure without doing a titration sleep study. The positive pressure trend can be used to determine whether treatment failure is caused by an inadequate pressure setting and to determine the amount of pressure to apply.

Adult↗
PubMed1976

[Effect of sulfhydryl compounds on the automatism of the pacemakers].

Experiments were performed on the isolated rabbit hearts and also on the hearts with complete atrioventricular block; a study was made of the effect of an excess or deficiency of the sulfhydryl groups on the automatism of the cardiac pace makers. Unithiol and cysteine in concentrations of 1-10(-6)-1-10(-4) g/ml were used as donors of sulfhydryl groups; deficiency of these groups was induced by the alloxan administration in concentrations of 1-10(-5)-5-10(-5) g/ml. Changes in the sulfhydryl group content produced no marked effect on the automatism of the synoatrial node. An excess of sulfhydryl groups promoted poststimulation depression of the automatism of the potential pace makers of the cardiac ventricles and could lead to the origination of Luciani's periods. On the contrary, in case of a deficiency of the sulfhydryl groups there was a sharp elevation of the automatism of the ventricular pace makers, the atrioventricular conduction became disturbed, and the poststimulation depression of the automatism became considerably diminished. Disturbances of the cardiac activity caused by the sulfhydryl group deficiency were completely eliminated by unithiol or cysteine.

Animals↗
PubMed1982

Automatic increases in mean airway pressure during mechanical ventilation.

The response of a time-cycled, continuous-flow, pressure-limited infant ventilator to changes in lung compliance was assessed by use of a variable-compliance test lung. A 50% reduction in lung compliance produced an automatic increase in mean airway pressure (MAP). Increases in MAP averaged 17% over baseline values. Factors that favored a large increase in MAP when lung compliance was reduced were a high original lung compliance, a low ventilator compliance, a high I:E, and ventilation with a triangular inspiratory pressure wave. The increase in MAP was accompanied by a change in the inspiratory pressure wave from triangular to square. Increases in MAP were not seen when the pressure wave was initially square. Automatic increases in MAP when lung compliance decreases may help to minimize decreases in PaO2; however, pulmonary barotrauma and increases in intracranial pressure could also result. The factors that allow for automatic MAP increases may also allow for automatic decreases in MAP as lung compliance improves. The advantages and disadvantages of automatic changes in MAP merit further study.

Airway Resistance↗
PubMed1999

Quantification and visualization of defects of the functional dopaminergic system using an automatic algorithm.

UNLABELLED: In SPECT, the binding of radiotracers in brain areas is usually assessed by manual positioning of regions of interest (ROIs). The disadvantages of this method are that it is an observer-dependent procedure and that it may not be sensitive for assessing defects significantly smaller than the ROI. To circumvent these limitations, we developed a fully automatic three-dimensional technique that quantifies neuronal radiotracer binding on a voxel-by-voxel basis. METHODS: To build a model of normal 123I-labeled N-omega-fluoropropyl-2beta-carbomethoxy-3beta-(4-iodophenyl) nortropane (FPCIT) binding, 17 studies of healthy volunteers were registered to the same orientation. After registration, the specific-to-nonspecific binding ratio was calculated for each voxel of the striatal volumes of interest (VOIs). The mean and SD of that binding ratio were then calculated on a voxel-by-voxel basis. For the analysis of 10 healthy volunteer studies (control group) and 21 studies of drug-naive patients with Parkinson's disease, the registration and calculation of the specific-to-nonspecific [123I]FPCIT binding ratio were performed by the same method. Subsequently, a voxel of the striata was classified as a diminished [123I]FPCIT binding ratio if its value was lower than the mean -2 x SD. For each subject, the defect size, the relative number of voxels with a diminished binding ratio and the binding ratio of the whole striatal VOIs were calculated and compared with the binding ratio as assessed by the traditional ROI method. RESULTS: The results of the automatic method correlated significantly with the results of the traditional ROI method. Furthermore, for the ipsilateral side, the automatically calculated defect size had less overlap between the patient and the control group than the traditionally calculated binding ratio. CONCLUSION: The method presented quantifies [123I]FPCIT binding ratio automatically on a voxel-by-voxel basis, by comparison with a model of healthy volunteers. We have shown that it is appropriate to use the automatic method as a replacement for the traditional manual method, which enables us to study the localized dopaminergic degeneration process in Parkinson's disease more precisely and without any inter- or intraobserver variability.

Algorithms↗
PubMed2001

Automatic buffer capacity model building for the purpose of water quality monitoring.

In this paper, buffer capacity profiles are used in the framework of automatic monitoring of water quality. The aim of the proposed methodology is to automatically and stepwise build buffer capacity models for each particular titrated sample, and to quantify the individual buffer systems that constitute the total buffer capacity. An automatic and robust model building algorithm has been developed and applied to many titration curves of effluent and river water samples. It is illustrated that the application of automatically built buffer capacity models mostly results in similar or better estimations of ammonium and ortho-phosphate in the samples compared to a priori fixed buffer capacity models. The automatic modelling approach is also advantageous for alarm generating purposes on e.g. river waters, because unexpected buffers are easily detected.

Automation↗
PubMed1992

Automaticity and the ACT* theory.

An explanation of automaticity within the framework of the Adaptive Control of Thought (ACT*) production system theory (Anderson, 1983, 1987) is presented. There is no automaticity mechanism per se in ACT*. This is as we would expect it to be. It would be the exception rather than the rule that we would find in a scientific theory mechanisms that directly correspond to natural language concepts. The critical question is whether ACT* can give an account of the phenomena associated with the term automaticity. This article is structured as follows: First, I will try to identify the phenomena of automaticity to be explained, then give a brief overview of the ACT* theory, and finally explain how these phenomena of automaticity are to be understood in terms of the theory.

Attention↗
PubMed1992

A parallel distributed processing approach to automaticity.

We consider how a particular set of information processing principles, developed within the parallel distributed processing (PDP) framework, can address issues concerning automaticity. These principles include graded, activation-based processing that is subject to attentional modulation; incremental, connection-based learning; and interactivity and competition in processing. We show how simulation models, based on these principles, can account for the major phenomena associated with automaticity, as well as many of those that have been troublesome for more traditional theories. In particular, we show how the PDP framework provides an alternative to the usual dichotomy between automatic and controlled processing and can explain the relative nature of automaticity as well as the fact that seemingly automatic processes can be influenced by attention. We also discuss how this framework can provide insight into the role that bidirectional influences play in processing: that is, how attention can influence processing at the same time that processing influences attention. Simulation models of the Stroop color-word task and the Eriksen response-competition task are described that help illustrate the application of the principles to performance in specific behavioral tasks.

Association Learning↗
PubMed1991

[Automatic reading of ABO and Rh groups on microplates using FMC medium and an IBG Systems reader].

We present in this paper our experience in the routine use of an automatic reader for microtiter plates (IBG Systems). A total of 2044 samples from blood donors have been tested for ABO (haematic and seric) and Rh (D antigen) blood group typing. The red blood cell samples have been tested against monoclonal anti-A, anti-B, anti-AB and anti-Rh 1 (D) sera (using two different anti-D reagents). As a negative control, 3% albumin solution was employed. In order to determine the seric groups, the plasma samples were tested against A1, A2, B and 0 cells. In all cases the red cells were suspended in Ficoll 400R-Methyl cellulose (FMC), and 0.01 Bromelin was added to red blood cell samples to be typed. The obstacles in the automatic readings were mainly solved by visual reading of the microplates. In the 2,044 samples analysed with the automatic reader, 19 discrepancies (0.94%) were found in ABO typing. In all cases the error was in the seric blood group. Three false positive reactions were found with 0 red cells. Two false negative with B red cells, interpreted by the automatic reader as doubtful results. Three positive readings were detected, in one case the positivity was due to alloantibodies (C + D specificities), the other two cases were autoagglutinations. False negative reactions were found, in 11 cases, 8 of them due to lipaemia and the remaining three were haemolysed plasma samples. It should be stressed that out of 19 cases of discrepancy, only 5 (0.24%) were due to the automatic reader while the remaining were due, to sample troubles.(ABSTRACT TRUNCATED AT 250 WORDS)

ABO Blood-Group System↗
PubMed1978

Epinephrine-induced automaticity of canine cardiac Purkinje fibers and its relationship to the adenylate cyclase-adenosine 3',5'-monophosphate system.

We studied the relationship between epinephrine-induced increases in automaticity and in the adenylate cyclase-adenosine 3',5'-monophosphate (cAMP) system in canine cardiac Purkinje fibers. In intact Purkinje fiber bundles superfused with Tyrode's solution, epinephrine induced a concentration-dependent increase in automaticity and in cAMP content. Both of these effects were reduced by propranolol. Decreasing the temperature of the superfusate from 37 degrees to 25 degrees C blocked the epinephrine-induced increase in automaticity, but not the increase in cAMP content. Addition of the metabolic blocking agent, iodoacetate, to the superfusate did not block the effect on Purkinje fiber automaticity, but the cAMP content did not increase. In Purkinje fiber bundle whole homogenates adenylate cyclase was stimulated more by isoproterenol than by epinephrine. Low concentrations of phenylephrine decreased adenylate cyclase activity; higher concentrations induced an increase toward control values. Iodoacetate did not significantly alter cyclase activity and did not affect its response to epinephrine. These students have shown that although intact Purkinje fiber bundles respond to epinephrine with increases in automaticity and cAMP content, these two events can be dissociated under appropriate conditions.

Action Potentials↗
PubMed1990

Phospholipase C modulates automaticity of canine cardiac Purkinje fibers.

Alpha-1 adrenergic agonists increase cardiac Purkinje fiber automaticity and elevate D-myo-inositol-trisphosphate (IP3) levels. To learn about the relationship between phosphoinositide metabolism and the modulation of cardiac rhythm, we used phospholipase C to activate phosphoinositide hydrolysis in an alpha-1 receptor-independent fashion and determined whether this intervention modulated automaticity. We used standard microelectrode techniques to study automaticity in adult Purkinje fiber bundles, fluorescence microscopy to study fura-2 fluorescence in isolated Purkinje and ventricular myocytes and standard biochemical techniques to measure inositol phosphate production in ventricular myocytes. Phospholipase C increased Purkinje fiber automaticity, a process that was enhanced by 10 mM lithium (which had no effect alone) and suppressed by verapamil or ryanodine (both 10 microM). Superfusion with 12-O-tetradecanoyl-phorbol-13-acetate phorbol ester, phospholipase D and A2, as well as L-alpha-phosphatidic acid, trypsin and D-myo-inositol-1-phosphate, D-myo-inositol-1,4-bisphosphate, IP3 and D-myo-inositol-1,4,5,6-tetrakisphosphate did not affect automatic rate or transmembrane potentials. Biochemical studies of ventricular myocytes demonstrated a phospholipase C-induced increase in intracellular and extracellular IP3, D-myo-inositol-1,4-bisphosphate and D-myo-inositol-1-phosphate at 3 min, with the extracellular increase persisting thereafter. Fluorescence microscopy with fura-2 revealed that phospholipase C increased systolic-free calcium.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Automatic rifle injuries: suicide by eight bullets. Report of an unusual case and a literature review.

A 25-year-old man committed suicide by shooting himself with eight bullets fired from a military rifle set on automatic. This rifle has two firing modes: an automatic mode and a self-loading, single-shot mode. Using this case as an example, some important aspects of firearm injuries are discussed with special emphasis on those points that are relevant to automatic military rifles and most applicable to forensic pathology practice. Some of the pathologic features of firearm wounds are reviewed and the role of the pathologist is discussed. Lastly, the most important points that help the pathologist to determine the type or nature of a firearm death--that is, whether it is an accident, homicide, or a suicide--are discussed. Classically, the number of the firearm wounds is used to differentiate suicide from homicide. As in the case reported here, however, when an automatic rifle or a military rifle set on automatic is used, the number of wounds is not a reliable indicator of the type of death.

Adult↗
PubMed1987

The effects of propranolol stereoisomers on nomotopic and ectopic cardiac automaticity in the rat.

The effect of the two isomers of propranolol was tested on nomotopic and ectopic cardiac automaticity in the rat. The spontaneously beating isolated right atria of the rat was used as a model for studying the effect of these drugs on nomotopic automaticity. Ectopic automaticity was induced by local injury of the isolated right ventricle. Both dextro and levopropranolol reduce nomotopic and abolish ectopic automaticity (ID50 was 0.17 microM for d-propranolol and 0.96 microM for 1-propranolol) in the rat heart. We conclude that the membrane stabilizing activity, which is present functionally in both stereoisomers, plays a significant role in the effect of these drugs on cardiac automaticity. On the other hand, the property of competitive blocking of beta-adrenergic receptors, which mainly resides in the levoisomer of propranolol does not seem to be essential for this effect.

Animals↗