Angiotensin II-mediated nondipping during sleep in healthy humans: effects on baroreflex function at subsequent daytime.

Blood pressure dipping at night is mediated by sleep-inherent, active downregulation of sympathetic vascular tone. Concomitantly, activity of the renin-angiotensin system is reduced, which might contribute to the beneficial effect of baroreflex downward resetting on daytime blood pressure homeostasis. To evaluate whether experimental nondipping mediated by angiotensin II during sleep would alter blood pressure and baroreflex function the next day in healthy humans, angiotensin-II or placebo (saline) was infused for a 7-h period at night, preventing blood pressure dipping in 11 sleeping normotensive individuals (5 males, balanced, crossover design).

Prolonged blood pressure elevation following continuous infusion of angiotensin II-a baroreflex study in healthy humans.

ANG II interacts with the sympathetic nervous system at central nervous blood pressure-regulating structures, including the baroreflex. It is unknown whether prolonged BP elevation mediated by high ANG II plasma levels could induce a persistent shift of the central nervous baroreflex setpoint, lasting beyond the short ANG II plasmatic half time of a few seconds, thereby consolidating elevated BP and/or increased SNA in healthy humans. In a blinded crossover design, ANG II or placebo (saline) was infused for a 6-h period in 12 resting normotensive students (6 males, 6 females) raising BP to borderline hypertensive levels.

From pantomime to actual use: how affordances can facilitate actual tool-use.

The main goal of the study was to investigate whether the presence of affordances, such as physical properties of given objects and resulting movement constraints, induce a performance increase in actual tool-use compared to demonstrating it with only the tool or pantomiming it without the tool and recipient object. In the present study the perception of affordances was manipulated by omission or supply of contextual information. The three execution modes - pantomiming, demonstration and actual use, - were investigated concerning the actions hammering and scooping in 25 patients with left unilateral brain damage and 10 healthy controls.

Circadian rhythms in handwriting kinematics and legibility.

The aim of the present study was to analyze the circadian rhythmicity in handwriting kinematics and legibility and to compare the performance between Dutch and German writers. Two subject groups underwent a 40 h sleep deprivation protocol under Constant Routine conditions either in Groningen (10 Dutch subjects) or in Berlin (9 German subjects). Both groups wrote every 3h a test sentence of similar structure in their native language.

Circadian rhythm in force tracking and in dual task costs.

The present study determined a circadian rhythm in force control during a visually guided tracking task under single task conditions (i.e., tracking task presented alone) and dual task conditions (i.

Circadian rhythm in handwriting.

The aim of the present study was to determine whether the motor process of handwriting is influenced by a circadian rhythm. Nine healthy young male subjects underwent a 40-h sleep deprivation protocol under constant routine conditions. Starting at 09:00 hours, subjects performed every 3 h two handwriting tasks of different complexity.

Circadian variations in the kinematics of handwriting and grip strength.

The present study determined whether the motor process of handwriting is influenced by a circadian rhythm during writing tasks of high everyday relevance and analyzed the relationship to the circadian rhythm of grip strength. Ten healthy young male subjects underwent a 40 h sleep-deprivation protocol under constant routine conditions. Starting at 09:00 h, subjects performed three handwriting tasks of increasing perceptual-motor complexity (writing a sentence, writing one's signature, and copying a text for 3 min) and assessed grip strength of both hands every 3 h.

Time-of-day effects on force control during object manipulation.

The aim of this study was to determine time-of-day variations of grip force control during a manipulative task. In particular, we repeatedly tested continuous up and down movements of a hand held instrumented object on two consecutive days. The movements caused fluctuations in the load that had to be compensated for by adequate grip forces.

Preserved and impaired aspects of predictive grip force control in cerebellar patients.

Objective: To analyze preserved and impaired aspects of feedforward grip force control during cyclic arm movements with a hand-held object after cerebellar damage.

Methods: We tested eight subjects with unilateral or bilateral cerebellar pathologies and eight healthy control subjects. Participants performed cyclic vertical arm movements with a hand held instrumented object at three different speeds.

Manual and hemispheric asymmetries in the execution of actual and pantomimed prehension.

Impairments of the ipsilesional hand after brain damage have been reported in goal-directed motor acts and in pantomimes; the relationship between both movement conditions is largely unknown. In the presented study, pantomimed and actual prehension was examined in 29 stroke patients with left brain damage (LBD) or right brain damage (RBD) as well as in 21 control subjects. Kinematic analyses revealed various performance differences between the conditions of movement execution and the subject groups.

The dependence of ipsilesional aiming deficits on task demands, lesioned hemisphere, and apraxia.

Neuroimaging studies as well as neurophysiological and lesion data indicate that the ipsilateral hemisphere plays a role in controlling the active limb. However, the nature and the conditions of this ipsilateral control are not well understood. We measured aiming movements with the ipsilesional limb toward targets with different characteristics which were made by patients with unilateral left brain damage (LBD) or right brain damage (RBD).

Grip force control during object manipulation in cerebral stroke.

Objective: To analyze impairments of manipulative grip force control in patients with chronic cerebral stroke and relate deficits to more elementary aspects of force and grip control.

Methods: Nineteen chronic stroke patients with fine motor deficits after unilateral cerebral lesions were examined when performing 3 manipulative tasks consisting of stationary holding, transport, and vertical cyclic movements of an instrumented object. Technical sensors measured the grip force used to stabilize the object in the hand and the object accelerations, from which the dynamic loads were calculated.

Ipsilesional deficits during fast diadochokinetic hand movements following unilateral brain damage.

Impaired sensorimotor function of the hand ipsilateral to a unilateral brain lesion has been reported in a variety of motor tasks; however, elementary diadochokinetic movements, such as tapping with the index finger, seem to be preserved in chronic-lesion patients. Three different diadochokinetic movements (forearm diadochokinesis, hand tapping (HT) and finger tapping (FT)) were tested in patients with left brain damage (LBD) and right brain damage (RBD) and control subjects. Movements were measured three-dimensionally and the kinematics of joint angles were analyzed.

Effect of decaffeination of coffee or tea on gastro-oesophageal reflux.

Background: Coffee and tea are believed to cause gastro-oesophageal reflux; however, the effects of these beverages and of their major component, caffeine, have not been quantified. The aim of this study was to evaluate gastro-oesophageal reflux induced by coffee and tea before and after a decaffeination process, and to compare it with water and water-containing caffeine.

Methods: Three-hour ambulatory pH-metry was performed on 16 healthy volunteers, who received 300 ml of (i) regular coffee, decaffeinated coffee or tap water (n = 16), (ii) normal tea, decaffeinated tea, tap water, or coffee adapted to normal tea in caffeine concentration (n = 6), and (iii) caffeine-free and caffeine-containing water (n = 8) together with a standardized breakfast.

Low-proof alcoholic beverages and gastroesophageal reflux.

Previous studies have demonstrated an increased gastroesophageal reflux after the ingestion of high-proof alcoholic beverages in normal subjects. Data on gastroesophageal reflux with usual amounts of low-proof alcoholic beverages are not available. The effect of white wine (7.

Absorption of a nutrient solution in chronic alcoholics without nutrient deficiencies and liver cirrhosis.

Duodenal and jejunal absorption of a nutrient solution at two different caloric loads (1.32 and 3.96 kcal/min = 5.