A rare cause of severe recurrent abdominal pain.

Recurrent abdominal pain may be enigmatic to solve. We report three cases, presenting after a protracted history of severe recurrent bouts of epigastric pain, impeding daily activities. In all cases, serology for strongyloidiasis stercoralis proved positive. In one case, stool examination was positive for larvae. Treatment with ivermectin or albendazole resulted in complete resolution of abdominal symptoms without recurrence in all three cases.

Worst-case prediction strategy in force programming when visual information is obstructed.

A person's strategy for applying force while lifting an object is dependent upon visual cues. This study investigated the alteration of strategy in force programming when visual information about an object's size was obstructed at the moment of lifting. Seven subjects were instructed to use a precision grip for repeated lifts of a cube-like grip apparatus attached to a box. The grip apparatus was a special device designed to measure grip and load forces. Three different-sized plastic boxes of equal weight were pseudorandomly presented by attaching them beneath the grip apparatus to the subjects in two visual conditions. In the Full-vision condition, subjects could view the box's size prior to lifting. In the Obstructed-vision condition, a screen prevented subjects from seeing the box size prior to lifting. In the Full-vision condition, the grip force and load force used by subjects on the grip apparatus increased with box size. In contrast, the subjects in the Obstructed-vision condition used forces appropriate for the largest box regardless of box size. The present results suggest that absence of size information may cause an alteration of strategy used to determine force output in that subjects may apply a maximum force adequate for the largest box, which could be called a "worst-case" prediction strategy, i.e., when there is doubt, the most secure lift may be selected for all possible cases.

Contribution of visually perceived size to the scaling of fingertip forces when lifting a 'small' object.

The effects of visually perceived size of an object on the scaling of fingertip forces during lifting tasks were investigated using a small and lightweight object. A grip apparatus was attached to the top surface of three different size boxes of equal weight. 15 healthy adults were asked to grasp the grip apparatus with the thumb and index finger, lift it to a height of 5 cm, hold it for 8 sec., and then put it down. Force transducers embedded in the grip apparatus measured grip and load forces. When subjects lifted the same size object repeatedly, there were no size effects on the grip and load forces used by each subject. When the size was pseudorandomly varied, however, the grip and load forces exerted by 7 subjects significantly increased with increased size, while there were no size effects for the remaining subjects (n = 8). These results suggest a smaller contribution of information on size to the force programming when lifting a small object than when lifting a larger and heavier object as used in previous studies.

Evidence of motor equivalence in a pointing task involving locomotion.

A pointing task was performed both while subjects stood beside and while subjects walked past targets that involved differing movement amplitudes and differing sizes. The hand kinematics were considered relative both to a fixed frame of reference in the movement environment (end effector kinematics) and to the subject's body (kinematics of the hand alone). From the former view, there were few differences between standing and walking versions of the task, indicating similarity of the kinematics of the hand. However, when the hand was considered alone, marked differences in the kinematics and spatial trajectories between standing and walking were achieved. Furthermore, kinematic analyses of the trunk showed that subjects used differing amounts of both flexion-extension and rotation movements at the waist depending on whether they were standing or walking as well as on the constraints imposed by target width and movement amplitude. The present results demonstrate the existence of motor equivalence in a combined upper and lower extremity task and that this motor equivalence is a control strategy to cope with increasing task demands. Given the complexity involved in controlling the arm, the torso, and the legs (during locomotion), the movements involved in the present tasks appear to be planned and controlled by considering the whole body as a single unit.

Increased Sensitivity to Changes in Visual Feedback With Practice.

In recent work investigating motor learning, the focus has been on the effect of modifying feedback at different levels of learning. Results suggest that learning is specific to the practiced conditions and that this specificity increases with practice. In a replication and extension of this previous work, 3 groups (N = 30 subjects) practiced a sequential positioning movement: Controls performed 300 trials with visually presented on-line kinematic feedback, whereas the other 2 groups, low practice (LP) or high practice (HP), performed, respectively, 50 or 300 trials without feedback. Pretest and posttest sessions of 10 trials each were performed with the on-line feedback. All groups improved with practice. It was apparent that the HP group exhibited more of a performance decrement in the posttest than the LP group did, suggesting that motor learning is the process of forming an increasingly specific sensorimotor representation. These results have implications for motor learning paradigms, models of motor learning, and training.

Are there task specific performance effects for differently configured numeric keypads?

Previous studies of numeric keypad user preference and performance have indicated that the telephone layout (TEL) was superior to the layout seen on computer keyboards and adding machines (ADD). A recent study (Straub and Granaas, 1993) suggested that the TEL preference was subject to task specific effects. To investigate the possibility of task specific performance in using keypads, 24 subjects were tested on four different keypad layouts (TEL, zero at top; TEL, zero at bottom; ADD, zero at top; ADD, zero at bottom) using three different tasks (four digit strings, seven digit strings, and seven digit strings depicted like standard North American telephone numbers). Results indicated that differences in rate of performance across the four keypad layouts were the result of zero placement, with the zero in the bottom position yielding the fastest keypad use. No significant differences were found for error rate across the different keypads. No task specific performance effects were found. These findings suggest that either the ADD or TEL layouts could be adopted universally for numeric keypads, with the stipulation that the zero key be placed below the other keys.

3 H-noradrenaline-accumulating ability of cholinergic nerve terminals in cat sympathetic ganglia.

1. After incubation of pieces of cat posterior mesenteric ganglion in [(3)H]-noradrenaline solution, the localization of the isotope was assessed by electron-autoradiography.2. Significantly higher concentrations of [(3)H]-noradrenaline were found over acetylcholinesterase-positive axons terminal on ganglion cells than in adjacent background areas.3. [(3)H]-Noradrenaline was not accumulated by ganglion cells under these circumstances.4. The significance of these findings in relation to previous physiological and pharmacological investigation is discussed.

In pursuit of the alpha-adrenoceptor: a fine-structural and electron autoradiographic study using 3H-phenoxybenzamine and smooth muscle from the cat and guinea-pig.

1. Electron microscopical evaluation of sets of serial fine sections of pancreatic arteriolar muscle of the cat showed no significant difference between the number of pinocytotic vesicles per unit length of smooth muscle cell membrane in ;synaptic' and ;non-synaptic' regions.2. With high resolution autoradiography, (3)H-phenoxybenzamine was found to be distributed over the cytoplasm and nuclei of smooth muscle cell profiles of guinea-pig vas deferens, although no localization in relation to discrete morphological organelles was evident.3. ;Specific protection' of alpha-adrenoceptors using 606 muM noradrenaline resulted in a significant diminution in the binding of (3)H-phenoxybenzamine as evidenced by a decrease in silver grain concentrations over smooth muscle cell profiles in autoradiographs.4. The significance of these findings in relation to the site and distribution of alpha-adrenoceptors is discussed.