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At least 379 records · Page 21Linked to original sources
PubMed1988

Activation sequence during atrial flutter in dogs with surgically induced right atrial enlargement: I. Observations during sustained rhythms.

The atrial activation sequences during 15 episodes of sustained atrial flutters were determined in the isolated hearts of four dogs with surgically induced right atrial enlargement (TI/PS dogs). These sequences were compared with the activation sequences of six episodes of nonsustained atrial tachyarrhythmias induced in three control hearts. Total endocardial activation of both atria during normal sinus rhythm and during the arrhythmias was determined first by recording simultaneously from 192 pairs of recording electrodes positioned into egg-shaped electrode arrays, and then by determining the moment of activation from each of the recorded electrograms. Isochronal maps of total activation were constructed by computer. Nonsustained atrial rhythms inducible in control hearts were due to circus movement excitation either in the left atrium (two episodes) or in the right atrium (four episodes). On the other hand, all 15 episodes of sustained atrial flutter induced and mapped in the TI/PS dog hearts were due to reentrant excitation in the enlarged right atrium. The reentrant pattern could be in a clockwise or counterclockwise pattern. In these episodes of stable flutter an area of functional block was an essential component to the reentrant excitation.

Animals↗
PubMed1988

Influence of the passive anisotropic properties on directional differences in propagation following modification of the sodium conductance in human atrial muscle. A model of reentry based on anisotropic discontinuous propagation.

Available models of circus movement reentry in cardiac muscle and of drug action on reentrant arrhythmias are based on continuous medium theory, which depends solely on the membrane ionic conductances to alter propagation. The purpose of this study is to show that the anisotropic passive properties at a microscopic level highly determine the propagation response to modification of the sodium conductance by premature action potentials and by sodium channel-blocking drugs. In young, uniform anisotropic atrial bundles, propagation of progressively earlier premature action potentials continued as a smooth process until propagation ceased simultaneously in all directions. In older, nonuniform anisotropic bundles, however, premature action potentials produced either unidirectional longitudinal conduction block or a dissociated zigzag type of longitudinal conduction (a safer type of propagation, similar to transverse propagation). Directional differences in the velocity of premature action potentials demonstrated that anisotropic propagation was necessary for a reentrant circuit to be contained within an area of 50 mm2, even with very short refractory periods. Quinidine produced Wenckebach periodicity, which disappeared after acetylcholine shortened the action potential. Quinidine also produced use-dependent dissociated zigzag longitudinal conduction in the older, nonuniform anisotropic bundles but not in the young, uniform anisotropic bundles. The electrophysiological consequence was that propagation events differed in an age-related manner in response to the same modification of the sodium conductance. The electrical events at microscopic level showed that conditions leading to obliteration of side-to-side electrical coupling between fibers (e.g., aging and chronic hypertrophy) provide a primary mechanism for reentry to occur within very small areas (1-2 mm) due to a variety of propagation phenomena that do not occur in tissues with tight electrical coupling in all directions.

Action Potentials↗
PubMed1990

Unidirectional block and reentry of cardiac excitation: a model study.

A computer model of a ring-shaped, one-dimensional cardiac fiber was used for examination of responses of propagation to premature stimuli applied under different degrees of both cell-to-cell coupling and membrane excitability. Results demonstrated the importance of cellular uncoupling in the genesis of unidirectional block and reentry. Propagation of excitation itself created a certain degree of functional inhomogeneity that provided necessary conditions for unidirectional block and reentry. The likelihood of induction of unidirectional block was proportional to the degree of cellular uncoupling. In contrast, uniform reduction in sodium channel conductance decreased the inducibility of unidirectional block. Nonsustained and sustained reentry was induced by a properly timed single premature stimulus during the refractory period of a propagating action potential. Reduction of the size of the reentry pathway resulted in an increased degree of interaction between the wavefront and its tail, which, in turn, changed the kinetics of the slow ionic channels, bringing about shortening of action potential duration. Alternans in action potential duration were also demonstrated during circus movement and were caused by the alternating kinetic properties of the slow ionic currents. Inhomogeneity along the reentry pathway in refractory period, in membrane excitability, in fiber cross-sectional area, or in gap junction resistance also provided conditions necessary for unidirectional block. The simulations suggested that an important role was played by cellular uncoupling in the genesis and maintenance of unidirectional block and reentry.

Action Potentials↗
PubMed2000

Pastoral counselors, educators, and clowns.

Examines the relationship between the pastoral counselor and educator and does so by exploring a metaphor suggested by a story by Carol Rogers about the famous circus clown, Otto Griebling. Illustrates each professional's duty to "draw or lead out" of his or her client or student, just as a clown does with an audience. Contends that pastoral counseling and education include "drawing or leading out" resources that are within the client/student, which is critical to the healing and/or learning process. Notes that assisting the client/student in developing his or her ability to draw out this inner resource is fundamental to the counselor's or educator's task of empowering the client or student to become mature, responsible individuals. Suggests that seeing one's relationship to the clown, a counselor or educator can be freed to facilitate this drawing out which ultimately benefits the client, student, and community.

Counseling↗
PubMedDate not supplied

Acute therapy of maternal and fetal arrhythmias during pregnancy.

Atrial premature beats are frequently diagnosed during pregnancy. Supraventricular tachycardia (atrial tachycardia, atrioventricular nodal reentrant tachycardia, circus movement tachycardia) is diagnosed less frequently. For acute therapy, electrical cardioversion with 50 to 100 J is indicated in all unstable patients. In stable supraventricular tachycardia, the initial therapy includes vagal maneuvers to terminate tachycardias. For short-term management, when vagal maneuvers fail, intravenous adenosine is the first choice drug and may safely terminate the arrhythmia. Ventricular premature beats are also frequently present during pregnancy and are benign in most patients; however, malignant ventricular tachyarrhythmias (sustained ventricular tachycardia, ventricular flutter, or ventricular fibrillation) may occur. Electrical cardioversion is necessary in all patients who are hemodynamically unstable with life-threatening ventricular tachyarrhythmias. In hemodynamically stable patients, initial therapy with ajmaline, procainamide, or lidocaine is indicated. In patients with syncopal ventricular tachycardia, ventricular fibrillation, ventricular flutter, or aborted sudden death, an implantable cardioverter-defibrillator is indicated. In patients with symptomatic bradycardia, a pacemaker can be implanted using echocardiography at any stage of pregnancy. The treatment of the pregnant patient with cardiac arrhythmias requires important modifications of the standard practice of arrhythmia management. The goal of therapy is to protect the patient and fetus through delivery, after which chronic or definitive therapy can be administered.

Anti-Arrhythmia Agents↗
PubMed2001

The relationship between interview characteristics and accuracy of recall in young children: do individual differences matter?

The relationship between interview characteristics and accuracy of recall in young children, as mediated by child characteristics, was examined. The interview characteristics included preinterview instructions and level of questioning. Fifty-six children ranging from ages 3 to 6 years participated in a Circus Day event and were interviewed 10 days later. Following either instructions or filler questions, children were questioned about the event. Results indicated that based on several individual difference factors, young children varied significantly in the accuracy of their interviews and their ability to resist misleading questions. However, individual differences did not mediate children's ability to benefit from different question types or preinterview instructions. As a whole, children provided limited information to the most open-ended questions and more correct information to highly structured questions. In contrast to the research with older children, younger children did not benefit from preinterview instructions. Suggestions for future research and implications for investigative interviews in the field of child abuse are discussed.

Black or African American↗
PubMed2003

Behavioral abnormalities in captive nonhuman primates.

In this study, we dealt with 11 species of nonhuman primates across 10 zoos in India. We recorded behavior as instantaneous scans between 9 a.m. and 5 p.m. In the study, we segregated behaviors for analyses into abnormal, undesirable, active, and resting. The 4 types of abnormal behavior exhibited included floating limb, self-biting, self-clasping, and stereotypic pacing. In the study, we recorded 2 types of undesirable behavior: autoerotic stimulation and begging. Langurs and group-housed macaques did not exhibit undesirable behaviors. A male lion-tailed macaque and a male gibbon exhibited begging behavior. autoerotic stimulation and self-biting occurred rarely. Males exhibited higher levels of undesirable behavior than did females. Animals confiscated from touring zoos, circuses, and animal traders exhibited higher levels of abnormal behaviors than did animals reared in larger, recognized zoos. The stump-tailed macaque was the only species to exhibit floating limb, autoerotic stimulation, self-biting, and self-clasping. Our results show that rearing experience and group composition influence the proportions of abnormal behavior exhibited by nonhuman primates in captivity. The history of early social and environmental deprivation in these species of captive nonhuman primates probably is critical in the development of behavioral pathologies. Establishing this will require further research.

Animals↗
PubMed1993

Regulation of CD18 expression in human neutrophils as related to shape changes.

The study analyses the distribution and quantitative expression of surface CD18 of neutrophils exposed to distinct stimuli that produce different types of continuous shape changes, including types that are associated with locomotion and others that are not. The chemotactic peptide N-formyl-L-norleucyl-L-leucyl-L-phenylalanine, colchicine and nocodazole were used to induce a polarized locomotor morphology, phorbol myristate acetate, 1,2-dioctanoylglycerol and 1-oleoyl-2-acetyl-glycerol to induce non-polar motile cells ruffling all over the surface and 2H2O to induce non-polar cells performing circus movements as have been previously described. Except for colchicine and nocodazole, these stimuli increased surface expression of CD18. Thus, stimulated shape changes are frequently, though not always, associated with increased surface expression of CD18. High concentrations (10(-7) to 10(-5) M) of phorbol myristate acetate but not of chemotactic peptide induced down-regulation of surface CD18. Cytochalasin D (10(-4) M) stimulated CD18 expression even though it inhibited shape changes. The surface distribution of CD18 determined by light microscopy was uniform in unstimulated cells or in various forms of stimulation except for cells treated with 10(-5) M cytochalasin D. Cytochalasin D (10(-5) M) produced CD18 accumulation at the pole opposite the F-actin cap. Experiments with colchicine, nocodazole, 2H2O and cytochalasin D suggest that microtubules as well as microfilaments modulate surface expression of CD18. The results suggest that protein kinase C and phosphatases play a role in regulating surface expression of CD18 in neutrophils.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1995

Clown doctors: shaman healers of Western medicine.

The Big Apple Circus Clown Care Unit, which entertains children in New York City hospitals, is compared with non-Western healers, especially shamans. There is not only superficial resemblance--weird costumes, music, sleight of hand, puppet/spirit helpers, and ventriloquism--but also similarity in the meanings and functions of their performances. Both clown and shaman violate natural and cultural rules in their performances. Both help patient and family deal with illness. Both use suggestion and manipulation of medical symbols in attempting to alleviate their patients' distress. Just as traditional ethnomedical systems have been integrated with Western medicine in other societies, clown doctors can provide complementary therapy that may enhance the efficacy of medical treatment in developed nations, particularly for children.

Adaptation, Psychological↗
PubMed1977

The effect of atropine on ventriculoatrial conduction during ventricular pacing in patients with and without Wolff-Parkinson-White syndrome.

Electrophysiological studies were performed in five patients, two with the three without Wolff-Parkinson-White (WPW) syndrome. In the former patients group, the paroxysmal supraventricular tachycardia (PSVT) was concluded to reflect the circus movement utilizing the normal atrioventricular (A-V) conduction system for antegrade conduction and the Kent bundle for the retrograde conduction. Ventriculoatrial conduction time (VACT) was measured during ventricular pacing before and after the administration of atropine sulfate. In patients without WPW syndrome, the VACT prolonged and subsequently second degree ventriculoatrial block developed when the pacing rate was increased progressively and atropine facilitated the retrograde conduction, suggesting the ventriculoatrial conduction took place via the normal A-V pathway. In contrast, the VACT in patients with WPW syndrome remained unchanged during ventricular pacing at rates of 145/min and more before and after atropine, indicating the retrograde conduction was taking place through the Kent bundle. It is discussed that the analysis of the VACT before and after atropine serves as an aid to differentiate the underlying mechanisms of PSVT in patients with WPW syndrome.

Adult↗
PubMed2000

Evaluation of a multiple-antigen enzyme-linked immunosorbent assay for detection of Mycobacterium tuberculosis infection in captive elephants.

Mycobacterium tuberculosis has become an important agent of disease in the captive elephant population of the United States, although current detection methods appear to be inadequate for effective disease management. This investigation sought to validate a multiple-antigen enzyme-linked immunosorbent assay (ELISA) for screening of M. tuberculosis infection in captive elephants and to document the elephant's serologic response over time using a cross-sectional observational study design. Serum samples were collected from 51 Asian elephants (Elephas maximus) and 26 African elephants (Loxodonta africana) from 16 zoos and circuses throughout the United States. Infection status of each animal was determined by mycobacterial culture of trunk washes. Reactivity of each serum sample against six antigens was determined, and the linear combination of antigens that accurately predicted the infection status of the greatest number of animals was determined by discriminant analysis. The resulting classification functions were used to calculate the percentage of animals that were correctly classified (i.e., specificity and sensitivity). Of the 77 elephants sampled, 47 fit the criteria for inclusion in discriminant analysis. Of these, seven Asian elephants were considered infected; 25 Asian elephants and 15 African elephants were considered noninfected. The remaining elephants had been exposed to one or more infected animals. The specificity and sensitivity of the multiple-antigen ELISA were both 100% (91.9-100% and 54.4-100%, respectively) with 95% confidence intervals. Mycobacterium bovis culture filtrate showed the highest individual antigen specificity (95%; 83.0-100%) and sensitivity (100%; 54.4-100%). Serum samples from 34 elephants were analyzed over time by the response to the culture filtrate antigen; four of these elephants were culture positive and had been used to calculate the discriminant function. Limitations such as sample size, compromised ability to ascertain each animal's true infection status, and absence of known-infected African elephants suggest that much additional research needs to be conducted regarding the use of this ELISA. However, the results indicate that this multiple-antigen ELISA would be a valuable screening test for detecting M. tuberculosis infection in elephant herds.

Animal Diseases↗
PubMed1998

Current treatment recommendations in antiarrhythmic therapy.

Over the past decade, various studies have demonstrated that class I antiarrhythmic drugs should be avoided in patients with heart failure, cardiac ischaemia or a previous myocardial infarction. In contrast, class II drugs (beta-blockers) reduce morbidity and may even lower mortality in patients suffering from moderate to severe heart failure. In these patients, careful titration of the drug dosage, frequently during hospital admission, may be necessary. If in the setting of heart failure ventricular arrhythmias are symptomatic and/or sustained, patients can be treated effectively, after appropriate treatment of the underlying disease, with the class III drug amiodarone. Unfortunately, this drug does not lower overall mortality, implying that prophylactic institution of amiodarone is not indicated. Pure class III antiarrhythmic drugs like d-sotalol, ibutilide and dofetilide show a high rate of torsade de pointes. Currently, only ibutilide has been approved for clinically monitored intravenous administration. Class IV drugs, the calcium channel blockers, are still very useful for rate control of atrial fibrillation and conversion or prevention of atrioventricular nodal re-entrant tachycardias and circus movement tachycardias using a (concealed) bypass tract. Finally, an implantable cardioverter defibrillator seems to improve overall survival in patients with life-threatening ventricular arrhythmias. This may imply that an increasing number of patients will be candidates for such a device. However, it will be necessary to await publication of data involving these devices from current ongoing studies.

Anti-Arrhythmia Agents↗
PubMed1975

Mode of spontaneous onset and termination of supraventricular tachyarrhythmias.

ECG tracings from 16 patients with spontaneous onset and/or termination of supraventricular tachyarrhythmias (SVTA) were studied. Of these recordings, 13 were made with a special technique which gives a high resolution of the atrial waves. At the onset of SVTA, the first atrial wave invariably had an aberrant configuration. The coupling index (coupling interval (P-1P) preceding cycle length) was 0.05 or less in 9 of 16 cases but more than 0.60 in 4 cases. In the 5 cases of onset of atrial fibrillation, the intervals between the first few atrial waves corresponded to a frequency of 300-350 per minute. Acceleration of the atrial activity occurred within the first 30 seconds. At the termination of SVTA, no successive modification of the atrial activity was found. The termination often did not occur at or shortly after a QRS complex. It is concluded that a premature atrial beat--even a single one--with a short coupling interval may well intiate a circus-movement SVTA, while an ectopic atrial beat with a long coupling interval apparently must be followed by repeated rapid discharges from the ectopic focus in order for SVTA to ensue. The functional conditions of the atria may then determine which kind of SVTA eventually results.

Adult↗
PubMed1989

The usefulness of amiodarone in management of refractory supraventricular tachyarrhythmias.

The efficacy of amiodarone was evaluated in 85 patients with supraventricular tachycardia (SVT) refractory to several antiarrhythmic agents (mean 3.8 +/- 1.0). All but six patients had organic heart disease. Patients were followed for 19 months (range 2-60 months). Response to amiodarone treatment was considered excellent (no recurrence of SVT) in 22 of 52 patients with paroxysmal atrial fibrillation (PAF), in four of 13 patients with chronic atrial fibrillation (CAF), and in three of 15 patients with Wolff-Parkinson-White syndrome-related circus movement tachycardia (WPW-CMT). Response was improved (marked improvement in symptoms with partial suppression of SVT) in 22 patients with PAF, in seven patients with CAF, in 10 patients with WPW-CMT, and in four patients with atrioventricular nodal reentry tachycardia. Response was considered poor (insignificant or no suppression of SVT) in three patients with PAF, in one patient with CAF, and in one patient with WPW-CMT. Seven patients required discontinuation of amiodarone due to adverse effects. We conclude that amiodarone is efficacious and relatively safe for control of SVT refractory to conventional antiarrhythmic agents irrespective of the underlying electrophysiologic mechanism.

Adult↗
PubMed1978

Normal fasting plasma glucose levels in some birds of prey.

Blood samples taken from five great horned owls (Bubo virginianus), eight red-tailed hawks (Buteo jamaicensis), four marsh hawks (Circus cyaneus), two prairie falcons (Falco mexicanus), five golden eagles (Aquila chrysaetos), and five white leghorn chickens (Gallus domesticus) that had been fasted for 24 h were used to determine plasma levels of glucose by the glucose oxidase method. The mean plasma glucose levels were: great horned owls 374.6 mg/100 ml, red-tailed hawks 346.5 mg/00 ml, marsh hawks 369.3 mg/100 ml, prairie falcons 414.5 mg/100 ml, golden eagles 368.4 mg/100 ml, and white Leghorn chickens 218.2 mg/100 ml. The plasma glucose levels obtained for the raptorial birds in this study were considerably higher than those found for the chickens. These values are discussed in relation to the carnivorous food habits of raptors.

Animals↗
PubMed1990

Serological evidence of herpesvirus infection in captive Asian elephants (Elephas maximus).

In mid 1988 a 3-yr-old Asian elephant (Elephas maximus) from a circus in Switzerland died following generalized manifestation of a herpesvirus infection. In an effort to determine prevalence of infection with the herpesvirus, and due to lack of a corresponding virus isolate, it was decided to evaluate contact animals and elephants from a second herd for antibody to bovine herpesvirus 1 (BHV1) and bovine herpesvirus 2 (BHV2). Of 15 sera tested four displayed low neutralizing antibody titers to BHV2. None of the sera neutralized BHV1. However, as evidenced by protein A-mediated immunoprecipitation of metabolically radio-labeled virus-infected and mock-infected cell antigens, followed by separation of precipitation products in SDS-polyacrylamide gels, the 15 sera precipitated multiple antigens from both viruses. Similar results were obtained when using BHV4 antigens. The extent of reaction was most distinct with respect to BHV2 antigens, less prominent with BHV1 antigens, and least with BHV4 antigens. The respective protein patterns, although less marked, matched well with those obtained with bovine reference sera. Additional evaluation of sera from six elephants from two zoos in the Federal Republic of Germany gave essentially identical results. It was concluded that at least one herpesvirus, immunologically related to BHV2, may be widely distributed among captive Asian elephants, and that this virus apparently does not cause overt disease in the majority of animals.

Animals↗
PubMed1999

Respiratory nematodiases in raptors in Quebec.

This is a retrospective study on wild raptors submitted to the Université de Montréal (Quebec, Canada) from 1989 to 1996. Cyathostoma spp. (Nematoda: Syngamidae) adults and/or eggs were found in air sacs, lungs, bronchi, and trachea of 12 raptors (Falconiformes and Strigiformes) from Quebec, Canada, belonging to eight different species, five of which are first host records for this parasite: barred owl (Strix varia), snowy owl (Nyctea scandiaca), northern harrier (Circus cyaneus), northern goshawk (Accipiter gentilis), and broad-winged hawk (Buteo platypterus). The infection was considered fatal in four birds, while no significant clinical signs were observed in the other cases. Major pathologic changes included diffuse pyogranulomatous air sacculitis, pneumonia, and bronchitis. A few unidentified larval nematodes embedded in a granuloma were found in the lungs of an additional Coopers' hawk (Accipiter cooperii); they were not considered clinically significant. A dead nematode, surrounded by necrotic inflammatory cells, was found in the air sac of a northern goshawk. The presence of nematodes in air sacs or lungs should be considered in wild raptors demonstrating respiratory problems.

Air Sacs↗
PubMed2001

Seroepizootiology of selected infectious disease agents in free-living birds of prey in Germany.

Four hundred forty-eight blood plasma samples from free-living birds of prey from Berlin and the Brandenburg area in eastern Germany were tested for antibodies against Newcastle disease virus (NDV), falcon herpesvirus (FHV), owl herpesvirus (OHV), and Chlamydia psittaci. Antibodies to NDV were detected in 6 (2%) of 346 tested diurnal birds of prey, whereas none of the owls (n = 55) was positive. The positive samples originated from two common buzzards (Buteo buteo), three ospreys (Pandion haliactus) and one marsh harrier (Circus aeruginosus). Titers varied between 1:8 and 1:32. Of 253 birds of prey one osprey (<1%) tested positive for antibodies to FHV with low titer of 1:6. This is the first detection of antibodies against FHV in an osprey. Furthermore, antibodies against OHV could be found in one tawny owl (Strix aluco) and one common buzzard (2 of 253, 1%) with low titers of 1:6. Of 422 birds of prey 267 (63%) tested positive for antibodies to Chlamydia psittaci with titers varying between 1:5 and 1:256 which reflects the ubiquitous occurrence of Chlamydia psittaci in these birds of prey.

Animals↗