Modulation of the QT interval: effects of graded exercise and reflex cardiovascular stimulation

1993 ◽  
Vol 75 (5) ◽  
pp. 2217-2223 ◽  
Author(s):  
J. A. Arrowood ◽  
J. Kline ◽  
P. M. Simpson ◽  
R. J. Quigg ◽  
J. J. Pippin ◽  
...  
Keyword(s):  
Normal Control ◽  
Qt Interval ◽  
Cold Pressor ◽  
Normal Subjects ◽  
Exponential Model ◽  
Cardiac Transplant ◽  
Control Subjects ◽  
Transplant Patients ◽  
Autonomic Changes ◽  
The Relationship

During exercise, as heart rate (HR) increases, the QT interval of the electrocardiogram shortens. The mechanism(s) involved in this QT shortening has not been clearly defined. To distinguish the influence of increased circulating catecholamines from myocardial efferent stimulation, the relationship between HR and QT interval was investigated during exercise and cardiovascular reflex stimulation in cardiac transplant patients and normal control subjects. Because of cardiac denervation, increases in HR in these patients are solely due to circulating catecholamines and thus allow isolation of their effect on the QT interval. Twenty-one cardiac transplant patients were studied and compared with 16 normal control subjects. The QT-HR relationship was determined according to an exponential model during treadmill exercise in both groups [QT = 0.12 + 0.492e(-0.008.HR) and QT = 0.12 + 0.459e(-0.007.HR) in normal subjects and transplant patients, respectively] and was statistically similar between groups, suggesting similar QT interval shortening in both groups. During cold pressor and Valsalva maneuvers, HR increased significantly in normal subjects only, whereas QT interval changed minimally in both groups. These results suggest that during exercise the QT interval is influenced predominantly by increases in circulating catecholamines rather than by neurally mediated reflex autonomic changes.

Vocal Tract Steadiness

1992 ◽  
Vol 35 (4) ◽  
pp. 761-768 ◽  
Author(s):  
Petra Zwirner ◽  
Gary J. Barnes
Keyword(s):  
Motor Control ◽  
Fundamental Frequency ◽  
Vocal Tract ◽  
Upper Airway ◽  
Normal Subjects ◽  
Subject Group ◽  
Formant Frequency ◽  
Control Subjects ◽  
Acoustic Analyses ◽  
The Relationship

Acoustic analyses of upper airway and phonatory stability were conducted on samples of sustained phonation to evaluate the relation between laryngeal and articulomotor stability for 31 patients with dysarthria and 12 non-dysarthric control subjects. Significantly higher values were found for the variability in fundamental frequency and formant frequency of patients who have Huntington’s disease compared with normal subjects and patients with Parkinson’s disease. No significant correlations were found between formant frequency variability and the variability of the fundamental frequency for any subject group. These findings are discussed as they pertain to the relationship between phonatory and upper airway subsystems and the evaluation of vocal tract motor control impairments in dysarthria.

Impaired sodium excretion in response to volume expansion induced by water immersion in insulin-dependent diabetes mellitus

1986 ◽  
Vol 71 (4) ◽  
pp. 403-409 ◽  
Author(s):  
J. P. O'Hare ◽  
J. M. Roland ◽  
G. Walters ◽  
R. J. M. Corrall
Keyword(s):  
Normal Control ◽  
Volume Expansion ◽  
Water Immersion ◽  
Normal Subjects ◽  
Diabetic Group ◽  
Dependent Diabetes Mellitus ◽  
Renal Response ◽  
Control Subjects ◽  
Fractional Excretion Of Sodium ◽  
Insulin Dependent

1. The renal response to volume expansion produced by water immersion to the neck at 35°C was examined in eight young normotensive uncomplicated insulin-dependent diabetic subjects and in eight matched normal control subjects. 2. Both the diabetic and normal subjects manifested a renal response of natriuresis and kaliuresis on immersion, but the natriuretic response was reduced in the diabetic group. Thus the induced excretion of sodium over the 4 h of immersion was 40 ± 5 mmol (mean ± sem) in the normal group compared with 22 ± 4 mmol in the diabetic group (P < 0.02). 3. In the normal subjects creatinine clearance did not change during immersion compared with pre-immersion control values while in the diabetic group it rose from pre-immersion control values of 112 ± 11 ml/min to a mean value of 127 ± 11 ml/min during immersion (P < 0.01). 4. The diabetic subjects thus excreted less sodium despite an increased filtered load during water immersion. Fractional excretion of sodium was significantly reduced in the diabetic subjects compared with the normal control subjects (P < 0.05). 5. The suppression of plasma renin and aldosterone was similar in normal and diabetic groups. 6. Tubular sodium retention could be an early functional change in the diabetic kidney, and be implicated in the development of diabetic nephropathy.

Effects of body position on the ventilatory response following an impulse exercise in humans

2002 ◽  
Vol 92 (4) ◽  
pp. 1423-1433 ◽  
Author(s):  
Philippe Haouzi ◽  
Bruno Chenuel ◽  
Bernard Chalon
Keyword(s):  
Ventilatory Response ◽  
Body Position ◽  
Work Rate ◽  
The Body ◽  
Cardiac Transplant ◽  
Transplant Patients ◽  
Leg Exercise ◽  
Muscle Groups ◽  
Response To Exercise ◽  
The Relationship

The aim of this study was to identify some of the mechanisms that could be involved in blunted ventilatory response (V˙e) to exercise in the supine (S) position. The contribution of the recruitment of different muscle groups, the activity of the cardiac mechanoreceptors, the level of arterial baroreceptor stimulation, and the hemodynamic effects of gravity on the exercising muscles was analyzed during upright (U) and S exercise. Delayed rise in V˙e and pulmonary gas exchange following an impulselike change in work rate (supramaximal leg cycling at 240 W for 12 s) was measured in seven healthy subjects and six heart transplant patients both in U and S positions. This approach allows study of the relationship between the rise inV˙e and O2 uptake (V˙o 2) without the confounding effects of contractions of different muscle groups. These responses were compared with those triggered by an impulselike change in work rate produced by the arms, which were positioned at the same level as the heart in S and U positions to separate effects of gravity on postexercising muscles from those on the rest of the body. Despite superimposableV˙o 2 and CO2 output responses, the delayed V˙e response after leg exercise was significantly lower in the S posture than in the U position for each control subject and cardiac-transplant patient (−2.58 ± 0.44 l and −3.52 ± 1.11 l/min, respectively). In contrast, when impulse exercise was performed with the arms, reduction of ventilatory response in the S posture reached, at best, one-third of the deficit after leg exercise and was always associated with a reduction inV˙o 2 of a similar magnitude. We concluded that reduction in V˙e response to exercise in the S position is independent of the types (groups) of muscles recruited and is not critically dependent on afferent signals originating from the heart but seems to rely on some of the effects of gravity on postexercising muscles.

Delay Versus Deviance in the Language Acquisition of Language-Impaired Children

1992 ◽  
Vol 35 (2) ◽  
pp. 373-383 ◽  
Author(s):  
Susan Curtiss ◽  
William Katz ◽  
Paula Tallal
Keyword(s):  
Language Acquisition ◽  
Normal Control ◽  
Normal Children ◽  
Language Impaired ◽  
Control Subjects ◽  
Rules And Principles ◽  
The Relationship ◽  
Linguistic Structures ◽  
Impaired Children

To investigate the issue of delay versus deviance in the language acquisition of language-impaired (LI) children, the order of acquisition of a set of linguistic structures and the relationship obtaining between one structure and another were examined in comprehension and production over a 5-year period in a group of LI and language-matched normal children. The results demonstrated a marked similarity between groups, both in the point at which mastery of individual structures was achieved and in the overall patterns of acquisition demonstrated. These data suggest that LI children are constructing grammars based on the same rules and principles as those of linguistically normal control subjects, and that their linguistic impairments may be principally processing, not representational, in nature.

scholarly journals Utjecaj semantičkih i sintaktičkih faktora na razumijevanje rečenica kod broca-afazičara

2018 ◽  
Vol 24 (1) ◽  
Author(s):  
Ivan Mimica ◽  
Vladimir Takšić
Keyword(s):  
Object Relations ◽  
Normal Control ◽  
Normal Subjects ◽  
Accusative Case ◽  
Semantic Cues ◽  
Action Verb ◽  
Control Subjects ◽  
Word Sequence ◽  
Compensatory Increase ◽  
Object Assignment

Yugoslav agrammatic aphasics and normal control subjects were tested for comprehension of agent-object relations in a series of simple Serbo-Croatian sentences consisting of two nouns and a transactive action verb. The availability of nominative and accusative case inflections and a semantic contrast was systematically varied across sentences. Sentences were also varied with respect to the two sequences NVN and VNN. An analysis of subjects’ agent-object assignments yielded the following results: While Broca’s aphasics showed some sensitivity to case inflections, their ability to process such cues was greatly impaired relative to normal subjects, for whom morphological cues were almost completely deterministic. Broca’s aphasics were impaired to a lesser degree in their ability to employ a strategy of »choose the first noun as agent« when case inflections and semantic contrasts were not available. While Broca’s aphasics showed no impairment in their ability to exploit semantic contrasts for agent-object assignment, there was no absolute compensatory increase in the degree to which they relied on semantic cues. Differences in word sequence had no effect on agent-object assignment in Broca’s aphasics. Finally, Broca’s aphasics frequently responded unsystematically when cues to agent-object relations occurred in isolation or in competition with one another, but when there was a convergence of cues, their performance approached that of normal subjects. This result was interpreted in terms of the accessing hypothesis.

scholarly journals The detection of intentional contingencies in simple animations in patients with delusions of persecution

2003 ◽  
Vol 33 (8) ◽  
pp. 1433-1441 ◽  
Author(s):  
S.-J. BLAKEMORE ◽  
Y. SARFATI ◽  
N. BAZIN ◽  
J. DECETY
Keyword(s):  
Normal Control ◽  
Affective Disorders ◽  
The Other ◽  
Persecutory Delusions ◽  
Control Subjects ◽  
Significant Difference ◽  
Contingent Condition ◽  
Schizophrenic Patients ◽  
The Relationship

Background. It has been proposed that delusions of persecution are caused by the tendency to over-attribute malevolent intentions to other people's actions. One aspect of intention attribution is detecting contingencies between an agent's actions and intentions. Here, we used simplified stimuli to test the hypothesis that patients with persecutory delusions over-attribute contingency to agents' movements.Method. Short animations were presented to three groups of subjects: (1) schizophrenic patients; (2) patients with affective disorders; and (3) normal control subjects. Patients were divided on the basis of the presence or absence of delusions of persecution. Participants watched four types of film featuring two shapes. In half the films one shape's movement was contingent on the other shape. Contingency was either ‘intentional’: one shape moved when it ‘saw’ another shape; or ‘mechanical’: one shape was launched by the other shape. Subjects were asked to rate the strength of the relationship between the movement of the shapes.Results. Normal control subjects and patients without delusions of persecution rated the relationship between the movement of the shapes as stronger in both mechanical and intentional contingent conditions than in non-contingent conditions. In contrast, there was no significant difference between the ratings of patients with delusions of persecution for the conditions in which movement was animate. Patients with delusions of persecution perceived contingency when there was none in the animate non-contingent condition.Conclusions. The results suggest that delusions of persecution may be associated with the over-attribution of contingency to the actions of agents.

Dynamic cerebral autoregulation is preserved in neurally mediated syncope

2001 ◽  
Vol 91 (6) ◽  
pp. 2493-2502 ◽  
Author(s):  
Ronald Schondorf ◽  
Reuben Stein ◽  
Richard Roberts ◽  
Julie Benoit ◽  
William Cupples
Keyword(s):  
Cerebral Autoregulation ◽  
Orthostatic Intolerance ◽  
Normal Subjects ◽  
Cerebrovascular Resistance ◽  
Control Subjects ◽  
Neurally Mediated Syncope ◽  
Cerebral Blood Velocity ◽  
Head Up Tilt ◽  
The Relationship ◽  
Dynamic Cerebral Autoregulation

To test whether cerebral autoregulation is impaired in patients with neurally mediated syncope (NMS), we evaluated 15 normal subjects and 37 patients with recurrent NMS. Blood pressure (BP), heart rate, and cerebral blood velocity (CBV) (transcranial Doppler) were recorded at rest and during 80° head-up tilt (HUT). Static cerebral autoregulation as assessed from the change in cerebrovascular resistance during HUT was the same in NMS and controls. Properties of dynamic cerebral autoregulation were inferred from transfer gain, coherence, and phase of the relationship between BP and CBV estimated from filtered data segments (0.02–0.8 Hz). During the 3 min preceding syncope, dynamic cerebral autoregulation of subjects with NMS did not differ from that of controls nor did it change over the course of HUT in patients with NMS or in control subjects. Dynamic cerebral autoregulation was also unaffected by the degree of orthostatic intolerance as inferred from latency to onset of syncope. We conclude that cerebral autoregulation in patients with recurrent syncope does not differ from that of normal control subjects.

Abnormal erythrocyte choline transport in patients with chronic renal failure

1991 ◽  
Vol 80 (2) ◽  
pp. 137-141 ◽  
Author(s):  
F. C. Fervenza ◽  
D. Meredith ◽  
J. C. Ellory ◽  
B. M. Hendry
Keyword(s):  
Renal Failure ◽  
Peritoneal Dialysis ◽  
Chronic Renal Failure ◽  
Continuous Ambulatory Peritoneal Dialysis ◽  
Normal Subjects ◽  
Choline Transport ◽  
Maintenance Haemodialysis ◽  
Control Subjects ◽  
Transplant Patients ◽  
The Mean

1. Erythrocyte choline transport has been studied in nine patients on maintenance haemodialysis for chronic renal failure, six patients on continuous ambulatory peritoneal dialysis, 31 patients with renal transplants and in nine normal control subjects. 2. The mean maximum rate of choline influx (Vmax., measured at an extracellular choline concentration of 250 μmol/l) was 66.7 (sd 14.1) μmol h−1 l−1 cells in patients on haemodialysis, 87.8 (sd 18.5) μmol h−1 l−1 cells in patients on continuous ambulatory peritoneal dialysis and 30.5 (sd 4.9) μmol h−1 l−1 cells in control subjects. The increase in choline flux in patients on haemodialysis and patients on continuous ambulatory peritoneal dialysis compared with control subjects was highly significant (P < 0.001). 3. Renal transplant patients showed variable values for the Vmax. of choline influx (range 17.7-71.7 μmol h−1 l−1 cells). The values showed a signifcant negative correlation with creatinine clearance and this correlation correctly extrapolated to the maximum choline flux in normal subjects and in patients on dialysis. 4. The kinetics of choline transport have been studied in erythrocytes of patients on haemodialysis and control subjects in ‘zero-trans’ conditions after depletion of intracellular choline. The mean Vmax. in these conditions was 38.4 (sd 4.6) μmol h−1 l−1 cells in patients on haemodialysis compared with 14.2 (sd 3.7) μmol h−1 l−1 cells in control subjects. The mean Km under ‘zero-trans’ conditions was 19.4 (sd 2.4) μmol/l in patients on haemodialysis and 7.4 (sd 1.4) μmol/l in control subjects. These differences were significant (P < 0.001).

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