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  • 2015-2019
  • 1995-1999  (316)
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  • 101
    Electronic Resource
    Electronic Resource
    Perceptual learning in tactile hyperacuity: complete intermanual transfer but limited retention (1998)
    Springer
    Experimental brain research 118 (1998), S. 131-134 
    Details
    ISSN: 1432-1106
    Keywords: Key words Touch ; Finger ; Spatial perception ; Texture ; Hyperacuity ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  We investigated intermanual transfer and long-term retention of practice-related perceptual learning in the domain of tactile hyperacuity. Subjects discriminated a row of three dots in which the central dot was offset laterally from a row without such offset. Performance at the right index fingerpad improved with practice. Practice effects transferred essentially completely to the left index fingerpad. When tested some months later at the right index fingerpad, long-term retention of learning was limited and further practice was required to stabilize discrimination thresholds. Intermanual transfer of tactile learning appears to be a general phenomenon, while long-term retention appears to be limited in hyperacuity tasks.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050263
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  • 102
    Electronic Resource
    Electronic Resource
    Spatial-frequency-related efficacy of visual stabilisation of posture (1998)
    Springer
    Experimental brain research 121 (1998), S. 471-477 
    Details
    ISSN: 1432-1106
    Keywords: Key words Posture ; Posturography ; Balance ; Vision ; Psychophysics ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The present study investigates the efficacy of visual stabilisation of posture for different spatial frequencies of a visual stimulus. Circular sine wave gratings were used to analyse the correlation between perception of motion in depth and stabilisation of fore-aft sway by the mechanism of detecting changes in target size. Body sway was recorded by a force-measuring platform (series A) and, in addition, by simultaneous tracking of infrared markers fixed to the subject’s body (series B). Mean velocity and amplitude (RMS) of body sway were calculated in both sagittal (a–p) and lateral (l–r) planes. Sagittal sway was of least magnitude when viewing contrast gratings with lowest thresholds, whereas higher thresholds resulted in increasing sway parameters. As intended by the design of the stimuli, sagittal sway was correlated closer with the stabilising effect exerted by the different stimuli than was lateral sway. Sway velocity was reduced more efficiently, however, with a lower correlation with the psychophysical transfer function, than was RMS sway. Since sway velocity measured by the platform is suggested to depend to a greter extent on dynamic muscle forces generated at each individual body site the results indicate that visual information can be used to reduce and thereby optimise dynamic muscle action (sway velocity) even though static body sway is either not or less reduced. A comparable economisation of sway velocity but not of RMS sway was also seen at the end of posture investigations, indicative of positive training effects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050483
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  • 103
    Electronic Resource
    Electronic Resource
    Oculomotor sequence learning: a positron emission tomography study (1998)
    Springer
    Experimental brain research 122 (1998), S. 1-8 
    Details
    ISSN: 1432-1106
    Keywords: Key words Regional cerebral blood flow ; Pre-supplementary motor area ; Prefrontal ; Intraparietal ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The purpose of this study was to identify the brain regions activated in relation to oculomotor sequence learning. Nine healthy subjects participated in the study, which consisted of three positron emission tomography scans. In the initial learning task, subjects were instructed to track a sequence of seven successive positions of visual targets and to memorize the order of the targets as well as their spatial locations. In the saccade task, subjects were instructed to track visual targets presented at random locations. In the control task, subjects were instructed to gaze at a fixation point. Fields showing significant regional cerebral blood flow change were determined from task-minus-control subtraction images. We determined that fields in the pre-supplementary motor area (pre-SMA), the intraparietal cortex, and the prefrontal cortex were activated not only in the learning-minus-control images but also in the learning-minus-saccade images. Although prefrontal and parietal activations were bilateral, pre-SMA activation was confined to the left hemisphere. The results indicate that these fields function as a part of the neural network involved in the learning of sequential saccadic eye movements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050485
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  • 104
    Electronic Resource
    Electronic Resource
    Interactions between vestibular and proprioceptive inputs triggering and modulating human balance-correcting responses differ across muscles (1998)
    Springer
    Experimental brain research 121 (1998), S. 478-494 
    Details
    ISSN: 1432-1106
    Keywords: Key words Vestibulospinal reflexes ; Proprioceptive reflexes ; Balance control ; Peripheral vestibular loss ; Visual modulation of postural responses ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Interactions between proprioceptive and vestibular inputs contributing to the generation of balance corrections may vary across muscles depending on the availability of sensory information at centres initiating and modulating muscle synergies, and the efficacy with which the muscle action can prevent a fall. Information which is not available from one sensory system may be obtained by switching to another. Alternatively, interactions between sensory systems and the muscle to which this interaction is targeted may be fixed during neural development and not switchable. To investigate these different concepts, balance corrections with three different sets of proprioceptive trigger signals were examined under eyes-open and eyes-closed conditions in the muscles of normal subjects and compared with those of subjects with bilateral peripheral vestibular loss. The different sets of early proprioceptive inputs were obtained by employing three combinations of support surface rotation and translation, for which ankle inputs were nulled, normal or enhanced, the knees were either locked or in flexion, and the trunk was either in flexion or extension. Three types of proprioceptive and vestibulospinal interactions were identified in muscles responses. These interactions were typified by the responses of triceps surae, quadriceps, and paraspinal muscles. The amplitudes of stretch responses at 50 ms after the onset of ankle flexion in triceps surae muscles were related to the velocity of ankle stretch. The amplitude of balance-correcting responses at 100 ms corresponded more with stretch of the biarticular gastrocnemius when the knee was re-extended at 60 ms. Absent stretch reflexes at 50 ms in triceps surae with nulled ankle inputs caused a minor, 12-ms delay in the onset of balance-correcting responses in triceps surae muscles. Vestibular loss caused no change in the amplitude of balance-correcting responses, but a negligible decrease in onset latency in triceps surae even with nulled ankle inputs. Stretch responses in quadriceps at 80 ms increased with the velocity of knee flexion but were overall lower in amplitude in vestibular loss subjects. Balance-correcting responses in quadriceps had amplitudes which were related to the directions of initial trunk movements, were still present when knee inputs were negligible and were also altered after vestibular loss. Stretch and unloading responses in paraspinals at 80 ms were consistent with the direction of initial trunk flexion and extension. Subsequent balance-correcting responses in paraspinals were delayed 20 ms in onset and altered in amplitude by vestibular loss. The changes in the amplitudes of ankle (tibialis anterior), knee (quadriceps) and trunk (paraspinal) muscle responses with vestibular loss affected the amplitudes and timing of trunk angular velocities, requiring increased stabilizing tibialis anterior, paraspinal and trapezius responses post 240 ms as these subjects attempted to remain upright. The results suggest that trunk inputs provide an ideal candidate for triggering balance corrections as these would still be present when vestibular, ankle and knee inputs are absent. The disparity between the amplitudes of stretch reflex and automatic balance-correcting responses in triceps surae and the insignificant alteration in the timing of balance-correcting responses in these muscles with nulled ankle inputs indicates that ankle inputs do not trigger balance corrections. Furthermore, modulation of balance corrections normally performed by vestibular inputs in some but not all muscles is not achieved by switching to another sensory system on vestibular loss. We postulate that a confluence of trunk and upper-leg proprioceptive input establishes the basic timing of automatic, triggered balance corrections which is then preferentially weighted by vestibular modulation in muscles that prevent falling. The organisation of balance corrections around trunk inputs portrayed here would have considerable advantage for the infant learning balance control, but forces balance control centres to rely on limited sensory information related to this most unstable body segment, the trunk, when triggering balance corrections.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050484
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  • 105
    Electronic Resource
    Electronic Resource
    Functional modification of agonist-antagonist electromyographic activity for rapid movement inhibition (1998)
    Springer
    Experimental brain research 122 (1998), S. 23-30 
    Details
    ISSN: 1432-1106
    Keywords: Key words Arm movement ; EMG modification ; Rapid movement inhibition ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Subjects made a fast elbow extension movement to designated target in response to a go signal. In 45% of trials a stop signal was presented after the go signal, to which subjects were asked to stop the movement as rapidly as possible. The interstimulus interval (ISI), or time interval between the go and stop signals, was randomly varied between 0 and 200 ms. Electromyographic (EMG) activity was recorded from biceps brachii and triceps brachii. Subjects could sometimes completely inhibit initiation of the movements when the ISI was 0 ms, but could rarely do so when the ISI exceeded 100 ms. For responses that were initiated but stopped on the way, the amplitude of the movement decreased linearly as the time interval (=modification time) from the stop signal to EMG onset increased. The peak velocity increased linearly as the movement amplitude increased. This tendency was similar to those previously reported in step-tracking movements with various amplitudes. In spite of the similarity in the kinematics of the movement, the EMG pattern was different from that of step-tracking movement. While the initial agonist burst (AG1) decreased linearly after the modification time exceeded 100 ms, the antagonist burst (ANT) increased compared with the go trial for the modification time from 0 to 200 ms and decreased after the modification time exceeded 300 ms. This change of activation is analogous to functional modification of middle-latency reflex EMG response to load, or cutaneous perturbation. In conclusion, it is suggested that adaptive mechanisms, which would functionally modify the reflex responses, are also continuously working during voluntary movements in response to sudden changes in environmental information.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050487
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  • 106
    Electronic Resource
    Electronic Resource
    Motor redundancy during maximal voluntary contraction in four-finger tasks (1998)
    Springer
    Experimental brain research 122 (1998), S. 71-78 
    Details
    ISSN: 1432-1106
    Keywords: Key words Hand ; Fingers ; Grip ; Force sharing ; Motor redundancy ; Voluntary movement ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The goal of the study was to investigate force-sharing patterns in multi-finger tasks. Maximal normal force (MNF) as well as the force-time curves produced by individual fingers were measured in 10 young male subjects in three tasks: (1) holding an instrumented handle in a pad opposition with the thumb at seven different locations, from opposing the index finger (L0) to opposing the little finger (L6); (2) holding the handle in a pad opposition with the thumb at an individually selected comfortable location; and (3) pressing with the four fingers against the same handle fixed to the external support. We found that: (1) The moment due to the normal finger forces changed systematically when the thumb position varied from L0 to L5 /L6, and it was equal to zero at a certain middle position of the thumb, the neutral position. At this position, the shear force produced by the fingers was zero. (2) The total MNF changed in an ascending-descending manner when the thumb position varied from L0 to L5 /L6. The highest value of the maximal total normal force was produced at a position of the thumb that was preferred as the most comfortable position in the grip task. (3) In the press task, the neutral line – the line with respect to which the moment generated by the four fingers equals zero – was at the same location as the preferred thumb position in the grip tasks. (4) Larger total normal force corresponded to smaller total shear forces. (5) In grip tasks, with the thumb in a comfortable position, the force-force relationships among fingers were approximately linear. Hence, in these thumb positions, the force-sharing pattern was established at the beginning of the trial. At the extreme positions of the thumb, irregular patterns of the force-force relationships were observed. (6) In trials with different thumb locations, a significant correlation was found between the maximal force produced by the index and small fingers. (7) Peak force exerted by individual fingers in the multi-finger tasks was much smaller than the maximal force displayed by the same fingers in the single-finger tasks. The peak force depended on the thumb position and varied from 11.3% to 65.2% of the maximal force exerted by the same finger in the single-finger task. With the thumb in the comfortable position, the relative peak force for all fingers was approximately at the same level, 50–55%. The data are in agreement with the hypothesis that the total force is shared among individual fingers, minimizing the moment with respect to the functional hand axis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050492
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  • 107
    Electronic Resource
    Electronic Resource
    Effect of focal cerebellar lesions on procedural learning in the serial reaction time task (1998)
    Springer
    Experimental brain research 120 (1998), S. 25-30 
    Details
    ISSN: 1432-1106
    Keywords: Key words Cerebellum ; Serial reaction time task ; Procedural memory ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Prior studies have shown that procedural learning is severely impaired in patients with diffuse cerebellar damage (cortical degeneration) as measured by the serial reaction time task (SRTT). We hypothesize that focal cerebellar lesions can also have lateralized effects on procedural learning. Our objective was to assess the effects of focal cerebellar lesions in procedural learning as measured by the SRTT. We studied 14 patients with single, unilateral vascular lesions in the territory of the posterior-inferior or superior cerebellar artery, who were compared with ten age- and sex-matched controls in a one-handed version of the SRTT. Patients with lesions at any other level of the brain or posterior fossa were excluded by cranial magnetic resonance imaging. Our results show that patients do not acquire procedural knowledge when performing the task with the hand ipsilateral to the lesion, but show normal learning with the contralateral hand. No correlation was found with the side, size, or vascular territory of the lesion. We conclude that procedural learning is impaired in hemispheric cerebellar lesions and involves only the hand ipsilateral to the lesion, which suggests a critical role for the cerebellum and/or crossed cerebellar-prefrontal connections in this type of learning.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050374
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  • 108
    Electronic Resource
    Electronic Resource
    Reach to grasp: the response to a simultaneous perturbation of object position and size (1998)
    Springer
    Experimental brain research 120 (1998), S. 31-40 
    Details
    ISSN: 1432-1106
    Keywords: Key words Reach to grasp ; Perturbation ; Kinematics ; Motor control ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  This study assessed the reach to grasp movement and its adaptive response to a simultaneous perturbation of object location and size. The aim was to clarify the means by which integration between the neural pathways modulating transport and manipulation is achieved. Participants (n = 11) were required to reach 30 cm to grasp a central illuminated cylinder of either small (0.7 cm) or large (8 cm) diameter. For a small percentage of trials (20/100) a visual perturbation was introduced unexpectedly at the onset of the reaching action. This consisted of a shift of illumination from the central cylinder to a cylinder of differing diameter (large in session A; small in session B) that was positioned 20° to the left (n = 10 trials) or to the right (n = 10) of the central cylinder. The subject was required to grasp the newly illuminated cylinder. Movement duration for these “double” (position and size) perturbed trials was much longer than those of control trials to the central cylinder (session A: by an average of 250 ms; session B: 180 ms), and the increased values were much greater than those reported previously in “single” perturbation studies where either size or location of the object was perturbed. Initial signs of a response to the “double” perturbation were seen almost simultaneously in the transport parameter of peak arm deceleration and in the manipulation parameter of maximum grip aperture, but these changes were not evident until more than 400 ms after movement onset, a response onset much later than that found in “single” perturbation studies. It is proposed that the visual change resultant from the double perturbation activates integration centres that at first gate the flow of information to the parallel channels of transport and manipulation. Following processing of this information, these centres act to instigate a synchronised and coordinated response in both components. These results add support to the existence of neural centres dedicated to the integration of parallel neural pathways, and which exercise flexibility in the degree to which these components are “coupled” functionally.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050375
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  • 109
    Electronic Resource
    Electronic Resource
    Changes in the symmetry of rapid movements Effects of velocity and viscosity (1998)
    Springer
    Experimental brain research 120 (1998), S. 52-60 
    Details
    ISSN: 1432-1106
    Keywords: Key words Movement symmetry ; Muscle viscosity ; Equilibrium-point hypotheses ; Load ; Muscle activation patterns ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Five subjects made rapid, discrete elbow flexion movements over different distances, against different inertial loads, as well as under distance and load combinations that kept movement time constant. The results demonstrated that an increase in peak movement velocity was associated with an increase in the temporal symmetry ratio of the movement (acceleration time divided by deceleration time), as well as with an increase in both agonist electromyographic (EMG) burst duration and antagonist EMG latency. Since an increase in peak movement velocity is associated with faster agonist muscle shortening, as well as with faster stretching of the antagonist muscle, we hypothesize that the velocity-related changes in movement symmetry can be viewed as, at least partially, a consequence of muscle viscosity. Viscosity increasingly resists the shortening agonist and assists the lengthening antagonist when movement velocity increases. Therefore, the agonist muscles require more time to produce the required impulse, while the antagonist muscle can brake the movement in a shorter period of time. In order to test the hypothesis that viscosity is responsible for the velocity-associated changes in the symmetry ratio, we performed a second experiment with distance and load combinations identical to those of the first experiment, but with different external viscous loads, which resisted the slower and assisted the faster movements. The results demonstrated that the movements became more symmetrical in the presence of the viscous load. There were also changes in agonist duration and antagonist latency. We conclude that changes in the symmetry associated with changes in movement velocity may be due to the effects of either muscle viscosity or changes in how muscles are activated to account for differences in viscous force.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050377
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  • 110
    Electronic Resource
    Electronic Resource
    Fast, anticipatory smooth-pursuit eye movements appear to depend on a short-term store (1998)
    Springer
    Experimental brain research 120 (1998), S. 129-133 
    Details
    ISSN: 1432-1106
    Keywords: Key words Eye movements ; Smooth pursuit ; Prediction ; Motor memory ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Anticipatory smooth pursuit before the expected appearance of a moving target can reduce the initial retinal blur caused by the 100-ms delay of visual feedback. Humans, though, can only voluntarily generate smooth velocities up to about 5°/s without a moving target. However, previous experiments have shown that repetitive brief presentations of a moving target every few seconds appear to charge an internal store, the contents of which can later be released to generate higher velocity anticipatory movements. This store’s longevity was assessed here by repetitively presenting a moving target for 500 ms at different known intervals up to 7.2 s. Target motion at 25°/s or 50°/s was tested, with presentations in alternate directions or the same direction. Anticipatory velocity, measured 100 ms after target onset, decreased with increasing interval for all target motion conditions. A decrease was still seen when accurate timing cues were given before each presentation, suggesting that the drive for anticipatory pursuit is held in a short-term store lasting a few seconds which can enhance the low velocities produced by volition alone. The results also demonstrate that high-velocity anticipatory pursuit helps to overcome the temporal delays in the system and allows target velocity to be matched at an earlier time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050385
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  • 111
    Electronic Resource
    Electronic Resource
    Phase-dependent electromyographic activity of the lower-limb muscles of a patient with clinically complete spinal cord injury during orthotic gait (1998)
    Springer
    Experimental brain research 120 (1998), S. 139-142 
    Details
    ISSN: 1432-1106
    Keywords: Key words Orthotic gait ; Paraplegia ; Electromyography ; Locomotion ; Spinal stepping generator ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  We examined the lower-limb electromyographic (EMG) activity from a patient with clinically complete spinal cord injury during orthotic gait. A newly developed gait orthosis was used to obtain bipedal locomotion. The surface EMG data during the gait together with the biomechanical variables were collected by way of a radio EMG system. A cyclic EMG activation pattern corresponding to the gait cycles were observed in each of the paralyzed lower-limb muscles during the orthotic gait. Although the EMG activation did not seem to contribute toward generating the gait, it showed some similarities to that of the infant stepping or immature gait. These results might be regarded as one of the indirect pieces of evidence that suggest the existence of a spinally originating motor mechanism underlying human locomotion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050387
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  • 112
    Electronic Resource
    Electronic Resource
    Gating of somatosensory evoked potentials during voluntary movement of the lower limb in man (1998)
    Springer
    Experimental brain research 120 (1998), S. 143-152 
    Details
    ISSN: 1432-1106
    Keywords: Key words Somatosensory evoked potential ; Gating ; H-reflex ; Voluntary movement ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Somatosensory evoked potentials (SEPs) evoked by stimulation of the tibial nerve (TN) in the popliteal fossa, the sural nerve (Sur) at the lateral malleole, and an Achilles tendon (Achilles) tap were recorded before and during voluntary plantarflexion, dorsiflexion, and cocontraction of the ipsi- and contralateral foot in normal subjects. Suppression (gating) of the TN-SEP began around 60 ms before the onset of electromyographic activity (EMG), and became maximal 50–100 ms after the onset of EMG. Similar gating was observed for the SEP evoked by activation of muscle afferents (Achilles) and cutaneous afferents (Sur). The TN-SEP was similarly depressed at the onset of a plantarflexion as at the onset of dorsiflexion. A depression, although much smaller, was also observed at the onset of movement of the contralateral limb. The depression of the TN-SEP after the onset of EMG decreased when fast-conducting afferents were blocked by ischemia below the knee joint. The TN-SEP was equally depressed during tonic dorsiflexion, plantarflexion, and cocontraction of dorsi- and plantarflexors. The TN-SEP was depressed for up to 300 ms when preceded by stimulation of Sur or a biceps femoris tendon tap. Gating of lower limb SEPs thus appears to have both central and peripheral components of which neither seems to be specific for the muscle being contracted or the sensory afferents being stimulated. We encourage that caution is taken when drawing functional conclusions regarding movement-specific modulation of afferent inflow to the somatosensory cortex based on observations of gating of lower limb SEP.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050388
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  • 113
    Electronic Resource
    Electronic Resource
    Effects of anterior cingulate cortex lesions on ocular saccades in humans (1998)
    Springer
    Experimental brain research 120 (1998), S. 173-183 
    Details
    ISSN: 1432-1106
    Keywords: Key words Cingulate cortex ; Eye movements ; Saccades ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Cerebral blood flow studies in humans suggest that the anterior cingulate cortex (ACC) could be involved in eye movement control. In two patients with a small infarction affecting the posterior part of this area (on the right side) and in ten control subjects, we studied several paradigms of saccadic eye movements: gap task, overlap task, antisaccades (using either a 5° or 25° lateral target), memory-guided saccades with a short (1 s) or long (7 s) delay, and sequences of memory-guided saccades. Compared with controls, patients had normal latency in the gap task but increased latency in the other tasks. The gain of memory-guided saccades was markedly decreased, bilaterally, whatever the duration of the delay. Patients made more errors than controls in the antisaccade task when the 5° lateral target was used, and a higher percentage of chronological errors in the sequences of saccades. These results show that the posterior part of the right ACC plays an important role in eye movement control and suggest that this area could correspond to a “cingulate eye field” (CEF). The role of this hypothetical CEF could be an early activation exerted on the frontal ocular motor areas involved in intentional saccades and also a direct action on brainstem ocular premotor structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050391
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  • 114
    Electronic Resource
    Electronic Resource
    Context-dependent reflex control: some insights into the role of balance (1998)
    Springer
    Experimental brain research 119 (1998), S. 251-259 
    Details
    ISSN: 1432-1106
    Keywords: Key words Reflexes ; Control strategies ; Tripping ; Balance ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Recent research suggests that the balance requirements of a task dictate the reflexive response. However, these observations were inferred indirectly from either different tasks or different phases of the same task. This study directly tested the hypothesis of balance-dependent control during recovery from an unexpected trip. The subjects were tripped in two different support conditions: unilimb support (provided by the stance limb) or trilimb support (provided by the stance limb and both arms placed on adjacent parallel bars). The subjects exhibited anticipatory changes: they biased the body center of mass toward the support limb in the mediolateral direction and elevated the swing limb higher when there was a possibility of being tripped. The electromyographic (EMG) latencies were not influenced by the threat to equilibrium. The magnitudes of the EMG reflexive response to the trip were clearly modulated as a function of the threat to stability, not in a simple manner, but rather in a complex manner, which optimized the recovery strategy. It is evident that the overriding concern, equilibrium control during locomotion, has a dominant influence on reflex modulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050339
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  • 115
    Electronic Resource
    Electronic Resource
    Magnetic transcranial stimulation at intensities below active motor threshold activates intracortical inhibitory circuits (1998)
    Springer
    Experimental brain research 119 (1998), S. 265-268 
    Details
    ISSN: 1432-1106
    Keywords: Key words Intracortical inhibitory circuits ; Brain stimulation ; Motor cortex ; descending volleys ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  A magnetic transcranial conditioning stimulus given over the motor cortex at intensities below threshold for obtaining electromyographical (EMG) responses in active hand muscles can suppress responses evoked in the same muscles at rest by a suprathreshold magnetic test stimulus given 1–5 ms later. In order to define the mechanism of this inhibitory effect, we recorded descending volleys produced by single and paired magnetic transcranial stimulation of motor cortex through high cervical, epidural electrodes implanted for pain relief in two conscious subjects with no abnormality of the central nervous system. The conditioning stimulus evoked no recognisable descending activity in the spinal cord, whilst the test stimulus evoked 3–4 waves of activity (I-waves). Conditioning stimulation suppressed the size of both the descending spinal cord volleys and the EMG responses evoked by the test stimulus. Inhibition of the descending spinal volleys was most pronounced at ISI 1 ms and had disappeared by ISI 5 ms. It was evident for all components following the I1-wave, while the I1-wave itself was not inhibited at all. We conclude that a small conditioning magnetic stimulus can suppress the excitability of human motor cortex, probably by activating local cortico-cortical inhibitory circuits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050341
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  • 116
    Electronic Resource
    Electronic Resource
    Force sharing among fingers as a model of the redundancy problem (1998)
    Springer
    Experimental brain research 119 (1998), S. 276-286 
    Details
    ISSN: 1432-1106
    Keywords: Key words Hand ; Finger forces ; Force sharing ; Motor redundancy ; Voluntary movement ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The aim of this study was to test Bernstein’s idea that motor synergies provide solutions to the motor redundancy problem. Forces produced by individual fingers of one hand were recorded in one-, two-, three-, and four-finger tasks. The subjects (n=10) were asked to produce maximal total force (maximal voluntary contraction, MVC) and to match a ramp total force profile using different combinations of fingers. We found that individual finger forces were smaller in multifinger MVC tasks than in single-finger tasks. The deficit increased with the number of fingers involved. A saturation effect was observed: when several effectors were involved, adding a new effector did not significantly change the total force output. The data confirmed the idea that the central neural drive arriving at the level of synergies has a certain limit, a ceiling, that cannot be exceeded. The central nervous system cannot maximally activate the muscles serving all the fingers at the same time. Secondly, during the course of ramp trials, forces produced by individual fingers were linearly related to each other. Hence, a force sharing pattern was established at the beginning of the trial and did not change during the ramp period. A hypothesis is suggested that force distribution among fingers may be organized so as to minimize unnecessary rotational moment with respect to the functional longitudinal axis of the hand. Finally, in the four-finger trials, variance of the total maximal force output in ten consecutive attempts was smaller than the sum of variances of the maximal individual finger forces. The finding suggests that the control system of the motor tasks studied involves at least two levels, a central neural drive level and a synergy level. At the synergy level, an intercompensation in individual finger force production is observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050343
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    Tilt perception during dynamic linear acceleration (1998)
    Springer
    Experimental brain research 119 (1998), S. 307-314 
    Details
    ISSN: 1432-1106
    Keywords: Key words Tilt ; Otolith organs ; Vestibular system ; Perception ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Head tilt is a rotation of the head relative to gravity, as exemplified by head roll or pitch from the natural upright orientation. Tilt stimulates both the otolith organs, owing to shifts in gravitational orientation, and the semicircular canals in response to head rotation, which in turn drive a variety of behavioral and perceptual responses. Studies of tilt perception typically have not adequately isolated otolith and canal inputs or their dynamic contributions. True tilt cannot readily dissociate otolith from canal influences. Alternatively, centrifugation generates centripetal accelerations that simulate tilt, but still entails a rotatory (canal) stimulus during important periods of the stimulus profiles. We reevaluated the perception of head tilt in humans, but limited the stimulus to linear forces alone, thus isolating the influence of otolith inputs. This was accomplished by employing a centrifugation technique with a variable-radius spinning sled. This allowed us to accelerate the sled to a constant angular velocity (128°/s), with the subject centered, and then apply dynamic centripetal accelerations after all rotatory perceptions were extinguished. These stimuli were presented in the subjects’ naso-occipital axis by translating the subjects 50 cm eccentrically either forward or backward. Centripetal accelerations were thus induced (0.25 g), which combined with gravity to yield a dynamically shifting gravitoinertial force simulating pitch-tilt, but without actually rotating the head. A magnitude-estimation task was employed to characterize the dynamic perception of pitch-tilt. Tilt perception responded sluggishly to linear acceleration, typically reaching a peak after 10–30 s. Tilt perception also displayed an adaptation phenomenon. Adaptation was manifested as a per-stimulus decline in perceived tilt during prolonged stimulation and a reversal aftereffect upon return to zero acceleration (i.e., recentering the subject). We conclude that otolith inputs can produce tilt perception in the absence of canal stimulation, and that this perception is subject to an adaptation phenomenon and low-pass filtering of its otolith input.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050346
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  • 118
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    Dipolar sources of the early scalp somatosensory evoked potentials to upper limb stimulation Effect of increasing stimulus rates (1998)
    Springer
    Experimental brain research 120 (1998), S. 306-315 
    Details
    ISSN: 1432-1106
    Keywords: Key words Somatosensory evoked potential generators ; Stimulus rates ; Brain electrical source analysis ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Brain electrical source analysis (BESA) of the scalp electroencephalographic activity is well adapted to distinguish neighbouring cerebral generators precisely. Therefore, we performed dipolar source modelling in scalp medium nerve somatosensory evoked potentials (SEPs) recorded at 1.5-Hz stimulation rate, where all the early components should be identifiable. We built a four-dipole model, which was issued from the grand average, and applied it also to recordings from single individuals. Our model included a dipole at the base of the skull and three other perirolandic dipoles. The first of the latter dipoles was tangentially oriented and was active at the same latencies as the N20/P20 potential and, with opposite polarity, the P24/N24 response. The second perirolandic dipole showed an initial peak of activity slightly earlier than that of the N20/P20 dipolar source and, later, it was active at the same latency as the central P22 potential. Lastly, the third perirolandic dipole exaplaining the fronto-central N30 potential scalp distribution was constantly more posterior than the first one. In order to evaluate the effect of an increasing repetition frequency on the activity of SEP dipolar sources, we applied the model built from 1.5-Hz SEPs to traces recorded at 3-Hz and 10-Hz repetition rates. We found that the 10-Hz stimulus frequency reduced selectively the later of the two activity phases of the first perirolandic dipole. The decrement in strength of this dipolar source can be explained if we assume that: (a) the later activity of the first perirolandic dipole can represent the inhibitory phase of a “primary response”; (b) two different clusters of cells generate the opposite activities of the tangential perirolandic dipole. An additional finding in our model was that two different perirolandic dipoles contribute to the centro-parietal N20 potential generation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050404
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    Target anticipation and impairment of smooth pursuit eye movements in schizophrenia (1998)
    Springer
    Experimental brain research 120 (1998), S. 316-324 
    Details
    ISSN: 1432-1106
    Keywords: Key words Smooth pursuit ; Schizophrenia ; Prediction ; Monitor theory ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  A reduced gain of smooth pursuit eye velocity has frequently been reported in schizophrenic patients. With respect to predictable stimuli, this could be due to a deficit in predicting the target path. To determine this contribution to smooth pursuit eye movement performance, we analyzed the ocular smooth pursuit response to a sinusoidally moving target that was suddenly stopped after some cycles of regular movement. Horizontal eye movements were recorded with infrared reflection oculography in a group of 17 schizophrenic in-patients and 16 age-matched healthy subjects for controls. The patients exhibited a reduced gain of smooth pursuit velocity, but phase lag was not different from the control group. After the unpredictable stop of target movement, predictive sinusoidal smooth pursuit was maintained for 150 to 200 ms in both groups. The resulting maximal position and velocity error was larger in the patient group. In conclusion, schizophrenic patients were able to generate a normal anticipatory component of smooth pursuit and to switch it off in response to external demands. They showed, however, an increased velocity of anticipatory pursuit, which might be used to compensate for the primary deficit of smooth pursuit velocity frequently found in schizophrenics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050405
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    Timing variability of repetitive saccadic eye movements (1998)
    Springer
    Experimental brain research 120 (1998), S. 325-334 
    Details
    ISSN: 1432-1106
    Keywords: Key words Eye movements ; Timing ; Saccades ; Human ; Wing and Kristofferson model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  We assessed the suitability of using the Wing and Kristofferson model for timing repetitive motor responses to analyse timing variability during repetitive saccadic eye movements. The model decomposes total timing variability (TV) into a central timing component (CV) and a peripheral motor delay component (MV). Eight normal subjects made voluntary horizontal saccades, in darkness, in synchrony with a regular auditory metronome. After 20 saccades had been produced, the metronome was switched off and subjects continued responding at the same frequency until 31 further saccades had been made. Inter-saccade intervals (ISIs) from the unpaced phase were used to calculate TV, CV and MV. Three different target intervals, paced by auditory cues, were used – 496 ms, 752 ms and 1000 ms. In the paced phase, subjects’ ISIs closely matched the auditory cue intervals. In the unpaced phase, subjects were clearly able to respond at three different frequencies. As predicted by the Wing and Kristofferson model, the durations of successive ISIs tended to be negatively correlated. As expected, TV and CV increased with increasing ISI. Contrary to the expectation of the model that MV would remain constant, we found that it increased with increasing interval. Our results do not conclusively demonstrate the validity of applying the Wing and Kristofferson model to the analysis of timing variability during repetitive saccadic eye movements. However, comparison with previous studies shows that, at least in normal subjects, it is equally valid to apply the model to the analysis of repetitive saccadic eye movements as it is to apply it to the analysis of data from other effectors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050406
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    Effects of pre-cues on voluntary and reflexive saccade generation II. Pro-cues for anti-saccades (1998)
    Springer
    Experimental brain research 120 (1998), S. 417-431 
    Details
    ISSN: 1432-1106
    Keywords: Key words Attention ; Orienting ; Saccadic reaction time ; Express saccade ; Anti-saccade ; Gap effect ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The reaction times of saccades (SRT) to a suddenly presented visual stimulus (pro-saccade) can be decreased and a separate mode of express saccades can occur when a gap paradigm is used (i.e. fixation-point offset precedes target onset by 200 ms). A valid peripheral cue, presented briefly (100 ms) before target onset, has been found to facilitate the generation of saccades to the target, thereby increasing the frequency of express saccades and decreasing the mean latency. This facilitation occurs only for cues that correctly indicate the direction of the subsequent target presentation (valid cues). The present study investigates the effects of valid cues on SRTs and error rate in the anti-saccade task (saccades in the direction opposite to the stimulus) by systematically varying the cue lead time (CLT) and using the gap and overlap conditions, i.e. fixation point remains on throughout the trial. For a CLT of 100 ms, both reaction times and error rates were significantly increased. With increasing CLT (200–500 ms), both the reaction times of the anti-saccades and the error rates returned to approximately control level, with CLT more than 200 ms in both the gap and the overlap condition. Additional experiments using non-informative cues in the overlap task showed that the reaction times of correct anti-saccades and the error rate were decreased when cue and stimulus appeared at the same side. Analysis of the erratic pro-saccades revealed that almost all of them were corrected, i.e. they were followed by a second saccade towards the required location. It is found that the correction times were usually very short, with intersaccadic intervals between 0 and 150 ms. We suggest that the orienting mechanism, elicited by a transient peripheral cue, relates to the command and the decision to make a pro- rather than an anti-saccade. The cue elicits pro-orienting towards its position when a pro-saccade is required, and anti-orienting when an anti-saccade is required. The orienting effect is transient and decays with CLTs of more than 200 ms; this result holds for both anti-saccades and pro-saccades. Since subjects reported that they could not prevent the erratic pro-saccades or were often not aware of them, we conclude that this orienting mechanism occurs automatically, beyond voluntary control.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050415
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    Isometric force-related activity in sensorimotor cortex measured with functional MRI (1998)
    Springer
    Experimental brain research 121 (1998), S. 59-64 
    Details
    ISSN: 1432-1106
    Keywords: Key words Functional MRI ; Isometric force ; Sensorimotor cortex ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Isometric force-related functional magnetic resonance imaging (fMRI) signals from primary sensorimotor cortex were investigated by imaging during a sustained finger flexion task at a number of force levels related to maximum voluntary contraction. With increasing levels of force, there was an increase in the extent along the central sulcus from which a fMRI signal could be detected and an increase in the summed signal across voxels, but these parameters were related in such a way that the signal from each voxel was similar for each level of force. The results suggest that increased neuronal firing and recruitment of corticomotor cells associated with increased voluntary isometric effort are reflected in an expansion of a relatively constant fMRI signal over a greater volume of cortex, rather than an increase in the magnitude of the response in a particular circumscribed region, possibly due to perfusion of an increase in oxygen-enriched blood over a wider region of the cortex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050437
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    Latency of saccades during smooth-pursuit eye movement in man Directional asymmetries (1998)
    Springer
    Experimental brain research 121 (1998), S. 92-98 
    Details
    ISSN: 1432-1106
    Keywords: Key words Saccade ; Latency ; Fixation ; Smooth pursuit ; Gap ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  To examine the effects of smooth-pursuit eye movements on the initiation of saccades, their latency was measured when subjects initially fixated or pursued a target. In half of the block of trials, the fixation or pursuit target was extinguished 200 ms before the saccade target was illuminated (gap trials). Reduction of the mean saccade latency in the gap trials (the “gap effect”) was evident even when the subjects were pursuing a moving target, consistent with previous observations. The effect of pursuit direction on saccade latency was also examined. Saccades in the same direction as the preceding pursuit (forward saccades) had shorter latencies than those in the opposite direction (backward saccades). This asymmetry was observed in both the gap and nongap trials. Although the forward-backward asymmetry was much smaller than the “gap effect”, it was statistically significant in six of eight cases. These results suggest that the preparation of saccades is affected by smooth-pursuit eye movements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050440
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    Inhibitory projections from pronator teres to biceps brachii motoneurones in human (1998)
    Springer
    Experimental brain research 121 (1998), S. 99-102 
    Details
    ISSN: 1432-1106
    Keywords: Key words Post-stimulus time histogram ; Biceps brachii ; Pronator teres ; Oligosynaptic group I inhibition ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Neural projections from the pronator teres (PT) muscle to biceps brachii (BB) motoneurones were studied in three healthy human subjects using a post-stimulus time histogram method. In 25 BB motor units, electrical stimulation to the PT nerve with intramuscular needle electrodes induced inhibition in nine units (36%), whereas facilitation was produced in 18 units (72%) by stimulation to the median nerve trunk with surface electrodes at the distal end of the intermuscular septum of the arm or in the cubital fossa. Six motor units (24%) received both inhibition (PT nerve stimulation) and facilitation (median nerve trunk stimulation). In the six, the latency of the inhibition was, on average, 1.2 ms longer than that of the facilitation. The stimulation site for the inhibition was, on average, 4.8 cm distal to that for the facilitation. The inhibition was evoked with an intensity well below the motor threshold. These findings suggest that BB motoneurones receive oligosynaptic inhibition of group I afferents from PT in human.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050441
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    Influence of head-to-trunk position on sound lateralization (1998)
    Springer
    Experimental brain research 121 (1998), S. 230-238 
    Details
    ISSN: 1432-1106
    Keywords: Key words Head position ; Eye position ; Interaural level difference ; Sound localization ; Spatial coordinates ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The effect of horizontal head position on the lateralization of dichotic sound stimuli was investigated in four experiments. In experiment 1, subjects adjusted the interaural level difference (ILD) of a stimulus (band-pass noise) to the subjective auditory median plane (SAMP) while simultaneously directing the beam of a laser attached to the head to visual targets in various directions. The adjustments were significantly correlated with head position, shifting in a direction toward the side to which the head was turned. This result was replicated in experiment 2, which employed a two-alternative forced-choice method, in which stimuli of different ILD were presented and left/right judgments were made. In both experiments, the average magnitude of the shift of the SAMP was about 1 dB over the range of head positions from straight ahead to 60° to the side. The shift of the SAMP indicates that any shift in head position induces a change in sound lateralization in the opposite direction, i.e., the intracranial sound image is shifted slightly to the left when the head is directed to the right and to the right when the head is to the left. In experiments 3 and 4, the effect of head position was compared with that of eye position by using the same methods as in experiment 2. Both shifts in SAMP, induced by either head- or eye-position changes, are in the same direction and, on average, of about the same magnitude (experiment 3), and head- and eye-position effects compensate approximately for each other during variations of head position when the gaze remains fixed to a visual target in space (experiment 4).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050456
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    Tactile impairments cannot explain the effect of age on a grasp and lift task (1998)
    Springer
    Experimental brain research 121 (1998), S. 263-269 
    Details
    ISSN: 1432-1106
    Keywords: Key words Aging ; Hand ; Motor control ; Manipulation ; Prehension ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  This experiment addressed the often-posed theory that age-related declines in manual dexterity result from diminished tactile function. We measured the time ’young’ subjects (n=33; mean=45 years) and ’old’ subjects (n=33; mean=74 years) needed to grip (thumb and index finger), lift, and transport a small metal sphere when vision was permitted and when blindfolded. Subjects began each trial by reaching for the sphere and were instructed to complete the entire task quickly. In the absence of visual information, placement of the finger and thumb for a secure grip and lift cannot be performed efficiently without tactile information. If age-related tactile changes are functionally significant for this task, then without visual information the ’old’ group should show a disproportionate increase in the duration of the grip and lift phase of the task compared to the ’young’ group. Perceptual thresholds for tactile pressure stimuli (Semmes-Weinstein filaments) confirmed well-known age-related changes. Age and vision effects were manifest mainly during the grip-lift phase (time from object contact to lift-off from its support surface), with the expected finding that the ’old’ group required more time than ’young’ group, regardless of visual condition. The main finding was that the ’grip-lift’ duration in the ’no-vision’ condition was about twice the duration observed in the ’vision’ condition for both age groups (ratios of 2.1 and 2.3 for ’young’ and ’old’, respectively). This similar relative slowing for the two groups fails to support the hypothesis that old adults’ ability to grip and lift the object was limited by changes in the availability or use of tactile information.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050459
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    Prediction of febrile seizures in siblings: a practical approach (1998)
    Springer
    European journal of pediatrics 157 (1998), S. 340-344 
    Details
    ISSN: 1432-1076
    Keywords: Key words Febrile seizures ; Genetics ; Family ; Risk factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To quantify the risk of febrile seizures (FS) in relatives of children with FS and to predict the risk of FS in siblings, we calculated cumulative risks of FS in first degree relatives of 129 children with FS. The study was conducted as a prospective follow up study of FS recurrences at the outpatient clinic of the Sophia Children's Hospital in Rotterdam. Thirteen parents and 12 siblings had experienced FS, accounting for a 6-year cumulative risk of 7%. The risk of FS was increased in relatives of children with recurrent FS (12%). The risk of FS in siblings (10%) in our study was more than twice the average risk in a similar population (4%). A positive FS history in a parent, young age at onset in the proband, and recurrences in the proband were selected in a multivariable prediction model. If two or more of these risk factors were present, the risk of West European siblings to develop FS was 46% (hazard ratio 5.4). Conclusion The cumulative risk of FS in siblings of children with FS is increased. The age attained risk of FS can be estimated using a practical model incorporating three readily available risk factors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004310050824
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    Pain and Stroop interference tasks activate separate processing modules in anterior cingulate cortex (1998)
    Springer
    Experimental brain research 118 (1998), S. 52-60 
    Details
    ISSN: 1432-1106
    Keywords: Key words Affect ; Limbic system ; Cognition ; Functional imaging ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Investigations of pain using functional imaging techniques have revealed an extensive central network associated with nociception. This network includes the thalamus, insula, prefrontal cortex and anterior cingulate cortex (ACC) as well as the somatosensory cortices. Positron emission tomography (PET) of regional cerebral blood flow (rCBF) has demonstrated activation of the ACC during cognitively challenging tasks such as the Stroop interference task and divided attention. One interpretation of this research is that ACC is involved in the general features of attention and that it does not play a specific role in pain processing per se. Three-dimensional PET imaging provides a method for assessments of rCBF in a single individual during multiple tasks. In addition, coregistration of PET and magnetic resonance (MR) images allows for better localisation of the PET signals so that differences in cortical activation sites can be more accurately determined. This approach was used to assess rCBF during the experience of pain by subtracting images collected during heat from those during noxious heat stimulation. Two regions of the ACC had elevated rCBF, one in the perigenual region and one in the mid-rostrocaudal region (i.e. midcingulate cortex). During the execution of the Stroop task, the group result showed the midcingulate region overlapping with the site seen during the experience of pain. This group result, however, was not confirmed in the individual subject analysis, which revealed widespread and independent areas of ACC response to pain and Stroop. It is concluded that the ACC contributes to multiple cognitive procedures. It is inadequate to describe the primary contribution of ACC to pain processing as “attention” because it is unlikely that the multiple small and independent activation sites produced by pain and Stroop subserve attentive processing throughout the brain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050254
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    Attentional coding for three-dimensional objects and two-dimensional shapes Differential interference effects (1998)
    Springer
    Experimental brain research 123 (1998), S. 289-297 
    Details
    ISSN: 1432-1106
    Keywords: Key words Kinematics ; Selective attention ; Reach to grasp ; Motor control ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The role played by the attentional mechanisms that enable dominance of relevant objects over distractor objects was investigated by measuring changes in the kinematics of the reach-to-grasp movement. Subjects reached towards three-dimensional (3D) stimuli while attention was diverted towards distracting information consisting of either two-dimensional (2D) projected shapes or 3D objects. Movement kinematics were influenced to a greater degree when a secondary task was performed involving a 3D object rather than a 2D projected shape. When the distractor was 3D, both the reaching and the grasping components were altered but, when it was 2D only, the reaching component was modified. It is suggested that, when attention is directed towards a distractor, it is associated with interference in the kinematics of the action towards the target. Further, the nature and dimensions of the distractor selectively influence the reach or the grasp component of a prehension movement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050571
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    Eye movements evoked by proprioceptive stimulation along the body axis in humans (1998)
    Springer
    Experimental brain research 120 (1998), S. 450-460 
    Details
    ISSN: 1432-1106
    Keywords: Key words Proprioceptive eye response ; Vestibulo-ocular reflex ; Cervico-ocular reflex ; Interaction ; Self-motion perception ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Proprioceptive input arising from torsional body movements elicits small reflexive eye movements. The functional relevance of these eye movements is still unknown so far. We evaluated their slow components as a function of stimulus frequency and velocity. The horizontal eye movements of seven adult subjects were recorded using an infrared device, while horizontal rotations were applied at three segmental levels of the body [i.e., between head and shoulders (neck stimulus), shoulders and pelvis (trunk stimulus), and pelvis and feet (leg stimulus)]. The following results were obtained: (1) Sinusoidal leg stimulation evoked an eye response with the slow component in the direction of the movement of the feet, while the response to trunk and neck stimulation was oriented in the opposite direction (i.e., in that of the head). (2) In contrast, the gain behavior of all three responses was similar, with very low gain at mid- to high frequencies (tested up to 0.4 Hz) but increasing gain at low frequencies (down to 0.0125 Hz). We show that this gain behavior is mainly due to a gain nonlinearity for low angular velocities. (3) The responses were compatible with linear summation when an interaction series was tested in which the leg stimulus was combined with a vestibular stimulus. (4) There was good correspondence of the median gain curves when eye responses were compared with psychophysical responses (perceived body rotation in space; additionally recorded in the interaction series). However, correlation of gain values on a single-trial basis was poor. (5) During transient neck stimulation (smoothed position ramp), the neck response noticeably consisted of two components – an initial head-directed eye shift (phasic component) followed by a shift in the opposite direction (compensatory tonic component). Both leg and neck responses can be described by one simple, dynamic model. In the model the proprioceptive input is fed into the gaze network via two pathways which differ in their dynamics and directional sign. The model simulates either leg or neck responses by selecting an appropriate weight for the gain of one of the pathways (phasic component). The interaction results can also be simulated when a vestibular path is added. This model has similarities to one we recently proposed for human self-motion perception and postural control. A major difference, though, is that the proprioceptive input to the gaze-stabilizing network is weak (restricted to low velocities), unlike that used for perception and postural control. We hold that the former undergoes involution during ontogenesis, as subjects depend on the functionally more appropriate vestibulo-ocular reflex. Yet, the weak proprioceptive eye responses that remain may have some functional relevance. Their tonic component tends to stabilize the eyes by slowly shifting them toward the primary head position relative to the body support. This applies solely to the earth-horizontal plane in which the vestibular signal has no static sensitivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050418
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    Differential effects of load stiffness on matching pinch force, finger span, and effort (1998)
    Springer
    Experimental brain research 120 (1998), S. 487-495 
    Details
    ISSN: 1432-1106
    Keywords: Key words Proprioception ; Pinch force ; Finger span ; Effort ; Motor command ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Disparities in load stiffness were used to differentiate and characterize pinch-force, finger-span, and pinch-effort matching in two experiments. All subjects squeezed a spring-loaded manipulandum in each hand using three-finger pinch. Subjects in the first experiment were instructed explicitly to match one of the three continua. Subjects matching force or span were told to attend carefully to sensations from the hand or arm and to ignore differences in the effort required to make the sensations equal. They had to achieve and hold a particular target force with the reference hand and then match force or span with the opposite hand, usually against a spring with a different stiffness. These subjects were given as much time as necessary to make their matches and were told which hand was serving as the reference in each trial. Effort-matching subjects were told to ignore peripheral sensations and to match effort or motor commands. These subjects were not told which hand was the reference and were given only 1 s to make a match, so they made matches by rapidly squeezing both manipulanda simultaneously and, presumably, with the same voluntary motor command. The matching behaviors of the three groups were clearly distinguishable and were consistent with instructions. Results were similar whether different subjects were assigned different instructions or the same subjects performed all three match types. In a second experiment, naïve subjects were given purposely ambiguous instructions without reference to a specific continuum and had no time or accuracy constraints. Subjects produced the same three sensorimotor behaviors obtained with explicit instructions, showing that the different behaviors were not artifacts of strict protocols. Taken together, the results show that force, span, and effort are distinct sensorimotor continua that can be judged reliably.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050422
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    Coordination among the body segments during reach-to-grasp action involving the trunk (1998)
    Springer
    Experimental brain research 123 (1998), S. 346-350 
    Details
    ISSN: 1432-1106
    Keywords: Key words Prehension ; Trunk ; Spatial coordination ; Human ; Motor control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  To understand the internal representations used by the nervous system to coordinate multijoint movements, we examined the coordination among the body segments during reach-to-grasp movements which involve grasping by the hand and reaching by the arm and trunk. Subjects were asked to reach and grasp an object using the arm only, the trunk only, and some combinations of both arm and trunk. Results showed that kinematic parameters related to the transport component of the arm and the trunk, such as peak velocity and time to peak velocity, varied across conditions and that the coordination pattern between the arm and trunk was different across conditions. However, parameters related to the grasp component, such as peak aperture, time to peak aperture, and closing distance, were invariant, regardless of whether the hand was delivered to the target by the arm only, the trunk only, or both. We hypothesize that a hierarchy of motor control processes exists, in which the reach and grasp components are governed by independent neuromotor synergies, which in turn are coordinated temporally and spatially by a higher-level synergy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050578
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  • 133
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    Colour constancy impairments in patients with lesions of the prestriate cortex (1998)
    Springer
    Experimental brain research 123 (1998), S. 154-158 
    Details
    ISSN: 1432-1106
    Keywords: Key words Colour constancy ; Extrastriate cortex ; V4 ; Cortical lesions ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Colour matching and colour constancy were studied in seven patients and 46 control subjects. Subjects were required to match Munsell Colour Chips presented under either identical or different illumination. Three of the patients had deficits in colour constancy, i.e. failure to compensate for the change in the wavelength composition of the illumination. Two of the patients with defective constancy had suffered bilateral cortical damage to the poterior lingual and fusiform gyri, and one patient had a lesion restricted to the same regions of the right hemisphere. Our observations indicate that these cortical areas, which include part of putative human area V4, play an important role in colour constancy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050556
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  • 134
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    Cortical control of saccades (1998)
    Springer
    Experimental brain research 123 (1998), S. 159-163 
    Details
    ISSN: 1432-1106
    Keywords: Key words Eye movements ; Saccade ; Cerebral cortex ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Saccadic eye movements are controlled by a cortical network composed of several oculomotor areas that are now accurately localized. Clinical and experimental studies have enabled us to understand their specific roles better. These areas are: (1) the parietal eye field (PEF) located in the intraparietal sulcus involved in visuospatial integration and in reflexive saccade triggering; (2) the frontal eye field (FEF), located in the precentral gyrus, involved in the preparation and the triggering of purposive saccades; and (3) the supplementary eye field (SEF) on the medial wall of the frontal lobe, probably involved in the temporal control of sequences of visually guided saccades and in eye-hand coordination. A putative cingulate eye field (CEF), located in the anterior cingulate cortex, would be involved in motivational modulation of voluntary saccades. Besides these motor areas, the dorsolateral prefrontal cortex (dlPFC) in the midfrontal gyrus is involved in reflexive saccade inhibition and visual shortterm memory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050557
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  • 135
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    Idiothetic input into object-place configuration as the contribution to memory of the monkey and human hippocampus: a review (1998)
    Springer
    Experimental brain research 123 (1998), S. 201-209 
    Details
    ISSN: 1432-1106
    Keywords: Key words Object-place configuration ; Monkey ; Hippocampus ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Memory for object-place configurations appears to be a common function of the hippocampus in the human and monkey brain. The nature of the spatial information which enters into these object-configural memories in the primate, and the location of the memories themselves, have remained obscure, however. In the rat, much evidence indicates that the hippocampus processes idiothetic spatial information, an estimate of the animal’s current environmental location derived from path integration. I propose that in primates the hippocampus provides idiothetic information about the environmental location of body parts, and that the main function of this information in the primate brain is to become configured with object-identity information provided by temporal lobe cortex outside the hippocampus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050562
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  • 136
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    Load compensation during homologous and non-homologous coordination (1998)
    Springer
    Experimental brain research 121 (1998), S. 223-229 
    Details
    ISSN: 1432-1106
    Keywords: Key words Interlimb coordination ; Inertial load ; Human ; Motor control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Two-limb coordination of homologous and non-homologous effectors was examined during isofrequency (1:1) and multifrequency (2:1) conditions. The coordination patterns involved flexion and extension movements in the sagittal plane and were performed under unloaded and single-limb (right arm) loaded conditions. Previous studies suggested that the lower degree of 1:1 synchronization observed during nonhomologous as compared to homologous coordination results from natural differences in biophysical (inertial) properties. Elaborating on this idea, adding weight to the right arm was hypothesized to modulate its inertial characteristics, rendering homologous limbs more dissimilar and nonhomologous limbs more similar by enhancing and decreasing their inertial differences, respectively. Therefore, the observations made during unloaded conditions were predicted to be completely reversed during loaded conditions. Findings revealed that during 1:1 coordination (experiment 1) single-limb loading resulted in a decreased relative phase stability, whereas relative phase accuracy depended upon the limb combination. In particular, phase-locking was more accurately maintained for loaded homologous than for nonhomologous limbs, whereas loading the nonhomologous limbs resulted in a deterioration of the quality of synchronization. These findings suggest that there is an additional explanation of differential coordination capabilities among limb combinations. It is hypothesized that the neural networks subserving the control centers of the homologous limbs are more tightly connected than those of the nonhomologous effectors, allowing 1:1 synchronization to be more successfully preserved in the face of (load) perturbations. During 2:1 coordination (experiment 2), the loading procedure disturbed the coordination dynamics across all limb combinations. That no differential effect of loading on effector combination was observed is possibly a result of the fact that only an initial level of practice was studied in which optimal relative phase dynamics are still being explored for both homologous and nonhomologous limbs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050455
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  • 137
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    Experimental jaw-muscle pain does not change heteronymous H-reflexes in the human temporalis muscle (1998)
    Springer
    Experimental brain research 121 (1998), S. 311-318 
    Details
    ISSN: 1432-1106
    Keywords: Key words Experimental muscle pain ; H-reflex ; M-response ; Jaw muscles ; Trigeminal reflexes ; Motoneuron excitability ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Muscle pain generally has an inhibitory effect on voluntary orofacial motor function. However, it is not known whether muscle pain causes direct or indirect changes in motoneuron excitability. In this study a monopolar needle stimulation technique was used to evoke the direct motor response (M-response) in the left masseter muscle and the heteronymous H-reflex in the left temporalis muscle as an indirect measure of motoneuron excitability. Series of 20 repeated electrical stimuli were delivered at 50% of maximal voluntary contraction (MVC) before, during, and after periods with experimental jaw-muscle pain in 11 healthy subjects. Pain was induced by standardized infusion of hypertonic (5%) saline into the mid-portion of the right masseter muscle. The mean pain intensity rating on a 100-mm visual analog scale was 42±5 mm. The short-latency responses (less than 6 ms) could be evoked in all subjects. Analysis of the latency and amplitude of the temporal H-reflex indicated no significant effect of jaw-muscle pain. The amplitude of the masseteric M-response was significantly smaller in the postpain condition than in the pain conditions (ANOVA, P=0.018), but no differences were found between the prepain and postpain conditions. In nine subjects, poststimulus periods (mean offset latency, 69.6±8.6 ms) with significantly (more than 50%) suppressed EMG activity were detected in the ipsilateral masseter muscle following the M-response (mean offset latency, 5.5±0.2 ms). These reflex responses did not show a systematic change during the pain conditions. In conclusion, acute contralateral jaw-muscle pain does not seem to modulate the motoneuron excitability as measured by the heteronymous H-reflex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050464
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    Neuroplasticity in the cat’s visual system Origin, termination, expansion, and increased coupling of the retino-geniculo-middle suprasylvian visual pathway following early ablations of areas 17 and 18 (1998)
    Springer
    Experimental brain research 121 (1998), S. 334-349 
    Details
    ISSN: 1432-1106
    Keywords: Key words Adaptive plasticity ; Behavioral sparing ; Extrastriate cortex ; Transsynaptic labeling ; Monkey ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  We used anterograde and retrograde transsynaptic pathway tracing techniques to reveal the retinal origin and the cortical termination of the expanded retino-geniculo-middle suprasylvian (MS) cortex pathway in adult cats which sustained lesions of areas 17 and 18 on the day of birth (P1) or at 1 month of age (P28). Following anterograde transsynaptic transport of tritiated amino acids from the eye, four major results were obtained: (1) a strong and specific pathway from retina through dorsal lateral geniculate nucleus (dLGN) to the posterior half of MS cortex was identified; this pathway is a substantial expansion of an insignificant pathway present in intact cats; (2) the terminus of the pathway was lower layer III and layer IV; (3) contralateral projections were stronger than ipsilateral projections; (4) projections in P28 cats were stronger than those in P1 cats. Following retrograde transsynaptic transport of WGA-HRP from posterior MS cortex, four additional results were obtained: (1) the pathway was enlarged and visuotopically organized; (2) the pathway arose primarily from α- and γ-retinal ganglion cells; (3) a small number of β-cells in P1 cats and a modest number in P28 cats also contribute to the pathway; (4) the combined numbers of γ- and β-cells relative to α-cells was greater in temporal retina than in nasal retina. The combined demonstration of both origin and terminus of the pathway with transsynaptic tracers argued strongly for high levels of coupling between primary and secondary pathway limbs in both P1 and P28 cats. This level of coupling, as well as other features of the pathway, have much in common with the retino-geniculo-17/18 pathway of intact cats. However, the retino-geniculo-MS system in P1 cats transmits primarily Y and W signals, in P28 cats X, Y, and W signals; whereas the retino-geniculo-17/18 pathway transmits primarily X and Y signals. These results have implications for understanding the repercussions of early visual cortex lesions in monkeys and humans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050466
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    Harvesting and preparation of cadaveric osseoligamentous lower cervical spine (C2-C7) for biomechanical testing (1998)
    Springer
    European spine journal 7 (1998), S. 66-68 
    Details
    ISSN: 1432-0932
    Keywords: Key words Autopsy ; Cadaver ; Cervical vertebrae ; Human ; Laboratory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Cadaveric osseoligamentous lower cervical spines (C2-C7) are often used in the investigation of spinal biomechanics in vitro. Surprisingly, however, the techniques of harvesting at postmortem and preparation of cadaveric osseoligamentous lower cervical spine for biomechanical testing have not been described in detail. We describe a simple and effective method that can be readily integrated into the routine autopsy procedure. Points on the avoidance of disfiguring the cadaver and damaging the spinal osseoligamentous structures are highlighted.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s005860050030
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  • 140
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    Influence of the cytochrome P4502D6*4 allele on the pharmacokinetics of controlled-release metoprolol (1998)
    Springer
    European journal of clinical pharmacology 54 (1998), S. 469-474 
    Details
    ISSN: 1432-1041
    Keywords: Key words CYP2D6 ; Genetic polymorphism ; Metoprolol ; Pharmacokinetics ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Aim: The aim of the present paper was to compare the pharmacokinetics of metoprolol in homozygous Caucasian volunteers for the wild-type CYP2D6 allele (CYP2D6*1/CYP2D6*1) and heterozygous (CYP2D6*1/CYP2D6*4) Caucasians. Methods: Thirty-six unrelated healthy male Caucasians were screened for two of the most frequently occurring mutant alleles (CYP2D6*3 and CYP2D6*4) using polymerase chain reaction (PCR). Twenty-four volunteers with a genotype suggesting a rapid hydroxylator phenotype were enrolled in a bioequivalence trial and each received in a randomized, cross-over fashion one of the three formulations compared. Each formulation contained 200 mg metoprolol tartrate/(tablet). In each of the three periods of the trial, one of the formulations was administered under fasting conditions in the morning on 4 consecutive days. Blood for quantification of metoprolol was drawn immediately before the last dose and in selected time intervals thereafter. A sensitive and specific high-performance liquid chromatography (HPLC) method with fluorescence detection was applied for the quantification of metoprolol. Pharmacokinetic parameters were determined for each subject and statistically compared in two groups of 16 homozygous (CYP2D6*1/CYP2D6*1) and six heterozygous (CYP2D6*1/CYP2D6*4) volunteers. Results: Significant differences between homozygous and heterozygous individuals were observed for all pharmacokinetic parameters. The AUC in the course of one those interval of 24 h (AUCτ), minium steady-state concentration (Cmin ss) and average steady-state concentration (Cav ss) values for heterozygous individuals were more than twice those of individuals. Significantly higher values for Css max , t1/2, half-value duration (HVD) and mean residence time (MRT) were also observed in heterozygous volunteers. The higher concentrations of metoprolol in heterozygous individuals also had pharmacodynamic consequences, namely, greater heart rate and blood pressure reduction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002280050495
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  • 141
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    Alternate-day buprenorphine dosing is preferred to daily dosing by opioid-dependent humans (1998)
    Springer
    Psychopharmacology 136 (1998), S. 217-225 
    Details
    ISSN: 1432-2072
    Keywords: Key words Buprenorphine ; Alternate-day dosing ; Heroin ; Methadone ; Human ; Reinforcer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Alternate-day buprenorphine dosing was compared to daily dosing in opioid-dependent outpatients and choice of alternate-day versus daily dosing was assessed. Four dosing schedules were presented in random order under blind and open dosing conditions. Subjects received two exposures to each dosing schedule. During daily dosing, subjects received maintenance doses every 24 h. During blind alternate-day dosing, subjects received double maintenance doses every 48 h; placebo was interposed on intervening days. During open alternate-day dosing, subjects received twice their maintenance dose on Monday, Wednesday and Friday and maintenance doses on Sunday. After completing two exposures to each dosing schedule, subjects chose either daily or alternate-day schedules each week for 1 month. Study participation was contingent on daily attendance and opioid abstinence. Ten subjects were exposed to the four conditions once. Seven subjects repeated these conditions and participated in the choice phase. The effects of daily versus alternate-day dosing were not influenced by blind or open dosing conditions. Subjects’ ratings of withdrawal, “sick” and sedation were lower during daily than during alternate-day dosing, but the difference between treatments was small. Nonetheless, subjects still chose alternate-day dosing on 96% of occasions, suggesting that the subject-rated differences between dosing schedules were not influential. These results extend prior findings to open-dosing conditions, and replicate the safety and acceptability of alternate-day buprenorphine treatment. Choice of alternate-day buprenorphine administration underscores the procedure’s clinical utility and potential use as a positive reinforcer to enhance opioid treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050559
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    Effects of pergolide on intravenous cocaine self-administration in men and women (1998)
    Springer
    Psychopharmacology 137 (1998), S. 15-24 
    Details
    ISSN: 1432-2072
    Keywords: Key words Cocaine ; Human ; Self-administration ; Pergolide ; Sex differences ; Subjective effects ; Performance ; Cardiovascular effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Clinical evidence suggests that pergolide, a D1/D2 dopamine receptor agonist, may be useful in maintaining cocaine abstinence. We investigated pergolide’s effects in a laboratory model of IV cocaine self-administration by humans. Twelve inpatient volunteers (7M, 5F), who reported spending an average of $170/ week on cocaine, received pergolide (0.05 mg BID) for 8 days and placebo for 8 days, with drug order balanced across subjects. Self-administration sessions occurred on the last 4 days of maintenance on each medication. A modified seven-trial progressive ratio choice procedure (0, 8, 16, 32 mg/70 kg cocaine versus $5) was utilized, with sessions consisting of: (a) two sample trials, where participants responded to receive the dose and tokens available that day, and (b) five choice trials, where participants chose between the available dose and tokens. Following each trial, the response requirement for the chosen option increased by 400. Maintenance on pergolide 1) decreased cocaine-induced increases in ratings of “High,”“Stimulated,” cocaine “Potency,” estimates of street value, and heart rate, 2) increased ratings of “I want cocaine,” and 3) had no effect on cocaine self-administration. The increased desire to use cocaine during pergolide maintenance suggests that it has limited treatment utility at this dose, but given the attenuation of cocaine’s subjective and cardiovascular effects, an investigation of a wider range of pergolide doses on cocaine self-administration and subjective effects is warranted.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050588
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    Isradipine prevents global and regional cocaine-induced changes in brain blood flow: a preliminary study (1998)
    Springer
    Psychopharmacology 136 (1998), S. 335-341 
    Details
    ISSN: 1432-2072
    Keywords: Key words Cocaine ; Brain blood flow ; Quantitative SPECT ; Ischemia ; Isradipine ; Stroke ; Calcium channel antagonist ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The L-type calcium channel antagonist, isradipine, reduces brain ischemia in animal models of ischemic stroke. These effects of isradipine appear more pronounced in dopamine (DA) rich brain regions. These same DA-rich brain regions have also been shown to be the areas most affected by cocaine-induced ischemic changes. Using a novel quantified approach to single photon emission computerized tomography, we demonstrated that isradipine pre-treatment prevented cocaine-induced ischemic changes, especially in these DA-rich brain regions. This is the first demonstration that any medication, including isradipine, can prevent the ischemic effects of cocaine on brain blood flow. Isradipine may, therefore, be a useful therapeutic agent for the prevention of brain ischemia in cocaine addicts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050575
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    Gender-dependent dissociation between oxytocin but not ACTH, cortisol or TSH responses to m-chlorophenylpiperazine in healthy subjects (1998)
    Springer
    Psychopharmacology 136 (1998), S. 342-348 
    Details
    ISSN: 1432-2072
    Keywords: Key words Adrenocorticotropic hormone (ACTH) ; Aldosterone ; Cortisol ; Human ; Meta-chlorophenylpiperazine (m-CPP) ; Thyrotropin (TSH) ; Oxytocin ; Serotonin agonist ; 5-HT2C receptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract m-chlorophenylpiperazine (m-CPP), a serotonin (5-HT) agonist with some selectivity for the 5-HT2C receptor subtype, which is widely used to examine 5-HT receptor function in human subjects, has been found to induce oxytocin and thyrotropin (TSH) responses in rodents. This study examined whether m-CPP had any effect on plasma oxytocin, TSH and aldosterone concentration in healthy volunteers using a double-blind, placebo-controlled crossover design. Plasma adrenocorticorticotropic hormone (ACTH) and cortisol responses, two generally accepted markers of m-CPP-induced 5-HT receptor activation, were measured in parallel. Male subjects (n = 7) received placebo, 0.25 and 0.5 mg/kg oral m-CPP. In female subjects (n = 5), the effects of placebo and 0.25 mg/kg m-CPP were studied. After placebo, given in the morning, ACTH, cortisol, TSH and aldosterone concentrations decreased over time. m-CPP 0.25 mg/kg avoided decreases in ACTH, cortisol and TSH concentrations; these responses were significant. At the dose of 0.5 mg/kg, m-CPP caused increase in ACTH, cortisol, TSH and aldosterone concentrations. Significant plasma oxytocin responses were found in female subjects only; thus this effect of m-CPP was statistically significantly gender dependent. Other responses to m-CPP were similar in male and female subjects. The present results suggest that there are clear differences, including dose and gender-dependent dissociations, among the 5-HT receptor agonist m-CPP-induced neuroendocrine responses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050576
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    Effects of dynorphin A(1–13) on opiate withdrawal in humans (1998)
    Springer
    Psychopharmacology 137 (1998), S. 326-332 
    Details
    ISSN: 1432-2072
    Keywords: Key words Dynorphin ; Opiate withdrawal ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The objectives of the current study were to determine 1) the effects of various doses of dynorphin A (1–13) on opiate withdrawal in humans and 2) the safety of dynorphin at these doses. Opiate dependent subjects who had been stabilized on morphine received a single IV dose of placebo, 150, 500 or 1000μg/kg dynorphin after exhibiting spontaneous withdrawal using a randomized, double-blinded, between-subjects study design. Observer Withdrawal Scores were lower in the 150 and 1000μg/kg groups as compared to placebo (P〈0.05) but no significant differences were observed on the observer-rated Wang or Sickness Scales. Significant decreases were also found for self-reported symptoms of nervousness, runny nose, sneezing, and painful joints in the 500μg/kg group. Significant increases in serum prolactin levels were seen after all dynorphin doses; however, these were not dose-related. Dynorphin A (1–13) was well tolerated and safe, with no changes in physiologic parameters. We conclude that dynorphin A (1–13) has a modest effect in reducing mild opiate withdrawal in humans and is well tolerated at doses up to 1000μg/kg.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050626
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    The effects of smoking on acoustic prepulse inhibition in healthy men and women (1998)
    Springer
    Psychopharmacology 137 (1998), S. 362-368 
    Details
    ISSN: 1432-2072
    Keywords: Key words Startle ; Prepulse inhibition ; Gating ; Human ; Smoking ; Nicotine ; Gender
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Acoustic prepulse inhibition (PPI) refers to the reduction of the startle reflex to an intense stimulus if it is preceded by a weak stimulus. Nicotine and smoking have been reported to enhance PPI in rats and in healthy men, respectively. We studied the influence of smoking on PPI in healthy men and women, comparing non-smokers, deprived smokers, and smokers smoking during the test session after deprivation or after ad libitum smoking. Smoking during the session enhanced PPI, without affecting startle reaction or habituation over time. In addition, the effect of smoking on PPI was gender dependent. In men, ad libitum smoking enhanced PPI compared with non-smokers, while, in women, deprivation reduced PPI and smoking restored PPI to the level of non-smokers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050631
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    Buspirone is differentiated from diazepam in humans using a three-response drug discrimination procedure (1998)
    Springer
    Psychopharmacology 138 (1998), S. 16-26 
    Details
    ISSN: 1432-2072
    Keywords: Key words Buspirone ; Diazepam ; Benzodiazepine ; Discrimination ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The discriminative stimulus effects of buspirone and diazepam were examined in 12 healthy volunteers using a three-response drug discrimination procedure and a within-subject design. During an initial sampling phase, the training drug conditions (placebo, 15 mg/70 kg buspirone, and 10 mg/70 kg diazepam) were identified to subjects by letter codes before oral drug administration. During a subsequent training phase, subjects earned money for correct drug identifications made two hours after drug administration. Ten out of 12 subjects acquired the three-response discrimination. When lower doses of buspirone (3.75 and 7.5 mg/70 kg) and diazepam (2.5 and 5.0 mg/70 kg) were tested in a subsequent generalization testing phase, both buspirone and diazepam produced dose-related increases in appropriate drug identifications, without significant cross-generalization. Analyses of standardized and unstructured self report questionnaires revealed that buspirone and diazepam produced different profiles of effects, and that buspirone was associated with a number of “negative” subject-rated effects including tension, nausea, and dizziness. These results demonstrate a distinct profile of discriminative stimulus and subjective effects for buspirone relative to diazepam which is consistent with its distinct pharmacological profile, and provide evidence for the sensitivity of the three-response drug discrimination procedure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050640
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    Cerebral effects of nicotine during cognition in smokers and non-smokers (1998)
    Springer
    Psychopharmacology 136 (1998), S. 179-189 
    Details
    ISSN: 1432-2072
    Keywords: Key words Nicotine ; Positron emission tomography ; Regional cerebral blood flow ; Brain activation ; Human ; Cognition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  For the smoker, nicotine has a positive effect on attention, cognition and mood. Conversely, nicotine abstinence is characterized by uncomfortable psychological effects such as impaired attention, but also irritability. We postulated that nicotine exerts an effect on cerebral areas important for attention and mood. Regional cerebral blood flow (rCBF), as an index for cerebral activity, was measured in both smokers and non-smokers. They were scanned during performance of a psychometric task with and without IV infusion of nicotine (1-methyl-2-[3-pyridyl1] pyrrolidine). Nicotine induced rCBF decreases in the anterior cingulate cortex and the cerebellum, and concomitant increases in the occipital cortex. The changes were similar in nature and magnitude in smokers and non-smokers. Thus, specific changes were induced in areas pertaining to the anterior attention system and to higher order visual cortex. We conclude that these effects on cerebral activity provide insights into the desired positive effects of nicotine on cognition as well as the negative effects experienced during nicotine abstinence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050554
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  • 149
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    Discriminative stimulus properties of low doses of ethanol in humans (1998)
    Springer
    Psychopharmacology 136 (1998), S. 379-389 
    Details
    ISSN: 1432-2072
    Keywords: Key words Ethanol ; Drug discrimination ; Human ; Skin conductance ; Interoceptive stimulus ; Self-rating
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Discriminative stimulus properties of low doses of ethanol were evaluated in humans using established behavioural drug discrimination procedures. Twenty-five moderate drinkers (12 females and 13 males) were trained to discriminate placebo from 0.2 g/kg ethanol in 200 ml tonic water mixed with Tabasco sauce and drunk in portions of 50 ml every 15 s. Seventeen of the subjects (ten females and seven males) were able to reach criterion performance (at least 80% correct responses). Generalisation responding across ethanol doses of 0 (placebo), 0.025, 0.05, 0.1 and 0.2 g/kg was examined the day after training using a procedure in which subjects reported the extent to which the test stimulus resembled the training dose. At the end of each generalisation session, self ratings of mood changes, physiological responses and performance in a working memory and a time estimation task were evaluated. Subjects were able to distinguish the three higher doses of ethanol from placebo. Self ratings indicated that subjects' ability to distinguish ethanol from placebo was related, at the highest dose, to change of taste, but to feelings of light-headedness at the lower doses. Ethanol administration influenced skin conductance measurements but there was no relationship found between changes in skin conductance and the ethanol discriminative stimulus. These data suggest a difference in the nature of the discriminative stimulus of ethanol between high (training) and low (generalising) doses as indicated in the subjective reports.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050581
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  • 150
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    Effortful processing is a requirement for nicotine-induced improvements in memory (1998)
    Springer
    Psychopharmacology 138 (1998), S. 362-368 
    Details
    ISSN: 1432-2072
    Keywords: Key words Nicotine ; Human ; Memory ; Attention ; Consolidation ; Effortful processing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  We report two studies examining the effects of nicotine on memory in minimally deprived smokers. In experiment 1, semantically related words were recalled significantly better than unrelated words following nicotine, even when volunteers were explicitly instructed to target the unrelated word set for recall. Experiment 2 examined the effect of nicotine on two different types of lexical association: association by joint category membership (semantically related items), and association by derived meaning (”encapsulated” word pairs). Nicotine-induced improvements in recall were observed only for category associates and not for encapsulated word pairs. This implies that explicit, effortful processing of material in the presence of nicotine is necessary for improved recall performance to be observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050682
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  • 151
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    Physical dependence increases the relative reinforcing effects of caffeine versus placebo (1998)
    Springer
    Psychopharmacology 139 (1998), S. 195-202 
    Details
    ISSN: 1432-2072
    Keywords: Key words Caffeine ; Reinforcement ; Drug choice ; Drug self-administration ; Physical dependence ; Withdrawal ; Multiple-choice procedure ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Using a within-subject cross-over design, this study examined the role of physical dependence in caffeine reinforcement by experimentally manipulating physical dependence. Each subject was exposed to two chronic drug phases (300 mg/70 kg/day caffeine and placebo) for 9–12 days, with order of phases counterbalanced across subjects. On 2 separate days immediately following each of the chronic drug exposures, subjects received acute doses of either caffeine (300 mg/ 70 kg) or placebo in counterbalanced order. The reinforcing effects of these drugs were then determined by using a multiple-choice procedure in which subjects made a series of discrete choices between receiving varying amounts of money or receiving the drug again, and a choice between the two drugs. To ensure that subjects completed the form carefully, following exposure to both of the acute drug administrations, one of the subject’s previous choices from the multiple-choice form was randomly selected and the consequence of that choice was implemented. When subjects were maintained on chronic caffeine, they were willing to forfeit significantly more money and showed significant increases in typical withdrawal symptoms (e.g. fatigue, mood disturbance) after receiving placebo as compared to the other three conditions. When subjects were maintained on chronic caffeine, they also chose to receive caffeine over placebo twice as often than when they were maintained on chronic placebo. These findings provide the strongest evidence to date indicating that caffeine physical dependence increases the relative reinforcing effects of caffeine versus placebo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050704
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  • 152
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    Acute tryptophan depletion attenuates the prolactin response to d-fenfluramine challenge in healthy human subjects (1998)
    Springer
    Psychopharmacology 138 (1998), S. 9-15 
    Details
    ISSN: 1432-2072
    Keywords: Key wordsd-Fenfluramine ; Tryptophan ; Prolactin ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Prolactin responses to d-fenfluramine (d-FEN) Challenge (0.5 mg/kg PO) were examined after pretreatment with and without acute tryptophan depletion (ATD) in six physically healthy male volunteers. Compared to pretreatment with SHAM-ATD, ATD pretreatment attenuated the PRL response to d-FEN Challenge in all subjects. These data suggest that PRL responses to d-FEN challenge reflect to a substantial degree the activity of newly synthesized 5-HT.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050639
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  • 153
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    The effect of genotype on response thresholds to sucrose and foraging behavior of honey bees (Apis mellifera L.) (1998)
    Springer
    Journal of comparative physiology 182 (1998), S. 489-500 
    Details
    ISSN: 1432-1351
    Keywords: Key words Honey bee ; Behavior ; Genetics ; Neurobiology ; Foraging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Honey bee foragers were tested for their proboscis extension response (PER) to water and varying solutions of sucrose. Returning pollen and nectar foragers were collected at the entrance of a colony and were assayed in the laboratory. Pollen foragers had a significantly higher probability of responding to water and to lower concentrations of sucrose. Bees derived from artificially selected high- and low-pollen-hoarding strains were also tested using the proboscis extension assay. Returning foragers were captured and tested for PERs to 30% sucrose. Results demonstrated a genotypic effect on PERs of returning foragers. The PERs of departing high- and low-strain foragers were consistent with those of returning foragers. The PERs were related to nectar and water reward perception of foragers. High strain bees were more likely to return with loads of water and lower concentrations of sucrose than foragers from the low pollen strain. Low-strain bees were more likely to return empty. We identified a previously mapped genomic region that contains a variable quantitative trait locus that appears to influence sucrose response thresholds. These studies demonstrate a gene-brain-behavior pathway that can be altered as a consequence of colony-level selection for quantities of stored food.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003590050196
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  • 154
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    Crosses between diabetic BB/OK and wild rats confirm that a third gene is essential for diabetes development (1998)
    Springer
    Acta diabetologica 35 (1998), S. 109-111 
    Details
    ISSN: 1432-5233
    Keywords: Key words BB rat ; Diabetes ; Genetics ; Crossing study
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Several crossing studies with diabetic BB rats have shown that in addition to the lymphopenia (Iddm1) and the MHC class II genes of the RT1u haplotype (Iddm2) there are further non-MHC genes essential for diabetes development. Because diabetes-resistant inbred rat strains may be homozygous for one of the diabetogenic non-MHC genes, masking the expression of diabetogenic genes and leading to an underestimation of the number of diabetogenic genes, we crossed wild and diabetic BB/OK rats. The F1 hybrids were backcrossed onto diabetic female (BC1W-F, n=97) and male BB/OK rats (BC1W-M, n=98) transferred to a specified-pathogen-free environment and studied for the frequency and age at onset of diabetes up to an age of 30 weeks. Comparing the results of these BC1 W hybrids with similarly derived hybrids using diabetes-resistant DA rats (BC1DA-F, n=113; BC1DA-M, n=216), the diabetes frequency in total was comparable indicating the action of three recessive genes. The percentage of diabetics in Iddm1 and Iddm2 homozygotes confirmed the existence of the third gene, Iddm3, but there were some sex differences; significantly more male than female BC1W-F and significantly more BC1DA-M than BC1DA-F males were diabetic. Regarding the age at onset, the BC1W-F hybrids manifested not only significantly earlier, but also more uniformly than BC1DA-F and BC1-M hybrids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s005920050114
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  • 155
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    Hepatocyte nuclear factor-1a gene and non-insulin-dependent diabetes mellitus in the Japanese population (1998)
    Springer
    Acta diabetologica 35 (1998), S. 150-153 
    Details
    ISSN: 1432-5233
    Keywords: Key words Non-insulin-dependent diabetes mellitus ; MODY ; Hepatocyte nuclear factor-1α ; Genetics ; Microsatellite polymorphism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Recently, hepatocyte nuclear factor-1α (HNF-1α, which is encoded by the TCF1 gene) mutations were reported in a subset of patients with maturity onset diabetes of the young (MODY3). We studied the contribution of TCF1 to genetic susceptibility to common non-insulin-dependent diabetes mellitus (type 2) in Japanese subjects by investigating allelic association with type 2 diabetes use of three markers. We also studied the frequency of the G191D mutation, the only mutation of TCF1 reported so far in late-onset type 2 diabetes. A total of 356 subjects were studied. There were no significant differences in allele frequency of the three markers between patients with type 2 diabetes and control subjects. A G191D mutation was not found in the subjects studied, giving a frequency of less than 0.4% in common type 2 diabetes. The lack of association of type 2 diabetes with three markers in and near TCF1 suggests that mutations in TCF1 derived from a limited number of founders are not a major cause of common type 2 diabetes even in the genetically homogeneous Japanese population. The data also indicate that the G191D mutation in TCF1 plays little, if any, role in susceptibility to common type 2 diabetes in the Japanese.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s005920050120
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  • 156
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    Cytological basis for a tetraspory in Cupressus sempervirens L. megagametogenesis and its implications in genetic studies (1998)
    Springer
    Theoretical and applied genetics 96 (1998), S. 776-779 
    Details
    ISSN: 1432-2242
    Keywords: Key words Cupressus sempervirens ; Cytology ; Megasporogenesis ; Megagametogenesis ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The processes of megasporogenesis and early megagametogenesis were cytologically investigated in Cupressus sempervirens L. in order to elucidate, at the cellular level, the origin of the megagametophyte. After pollination, sporogenous tissue developed in the chalazal region of the nucellus, but only one megaspore mother cell differentiated and divided meiotically without cell-wall formation. This led to the development of a cell with four nuclei which directly functioned as a megaspore. The C. sempervirens megagametophyte is thus tetrasporic, in contrast to the majority of conifers where the megagametophyte is monosporic. The consequenses of this observation are discussed from a genetics point of view.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220050801
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  • 157
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    Microsatellite DNA in Actinidia chinensis: isolation, characterisation, and homology in related species (1998)
    Springer
    Theoretical and applied genetics 97 (1998), S. 1269-1278 
    Details
    ISSN: 1432-2242
    Keywords: Key words Simple sequence repeat (SSR) ; Microsatellites ; Molecular markers ; Genetics ; Kiwifruit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  We have isolated and sequenced 263 microsatellite-containing clones from two small insert libraries of Actinidia chinensis enriched for (AC/GT) and (AG/CT) repeats, respectively. Primer pairs were designed for 203 microsatellite loci and successfully amplified from both plasmid and A. chinensis genomic DNA. In this paper we report the sequences of 40 primer pairs for which we have demonstrated Mendelian segregation in the progeny from controlled crosses. The polymorphism of ten microsatellites of each type was evaluated in four diploid and six tetraploid genotypes of A. chinensis. All microsatellites proved to be polymorphic, the number of alleles per locus detected in polyacrylamide sequencing gels ranging from 9 to 17. The high degree of polymorphism in Actinidia renders these markers useful either for mapping in A. chinensis or for fingerprinting cultivars of both domesticated kiwifruit species (A. chinensis and A. deliciosa). While most primer pairs produced single amplification products, about 20% generated banding patterns consistent with the amplification of two different loci. This supports the hypothesis that diploid species of Actinidia (2n=2x=58) are polyploid in origin with a basic chromosome number x=14/15 and that chromosome duplication may have occurred during the evolution of the genus. Finally, we have assayed the cross-species transportability of primer pairs designed from A. chinensis sequences and have found extensive cross-species amplification within the genus Actinidia; 75% of primer pairs gave successful amplification in the eight species assayed (A. arguta, A. rufa, A. polygama, A. chrysantha, A. callosa, A. hemsleyana, A. eriantha, and A. deliciosa), which are representative of the four sections into which the genus is currently split.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220051019
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  • 158
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    Fruit tree genetics at a turning point: the almond example (1998)
    Springer
    Theoretical and applied genetics 96 (1998), S. 588-601 
    Details
    ISSN: 1432-2242
    Keywords: Key words Fruit trees ; Genetics ; Almond ; Prunus amygdalus ; Breeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The large size and the long generation time of fruit trees generally reduce the possibilities of obtaining genetic information on the transmission and heritability of useful agronomic traits in these species. However, from breeding work carried out with fruit trees, an important amount of data is now available, although large differences are apparent among the different species. There is not much information known about almond compared to what is available on other Prunus fruit species, but more data have been accumulated on it than on most of the other nut trees, thus making almond special among all the temperate fruit and nut species. Only five qualitative traits have been described in almond, with an additional two also possibly qualitative. Heritabilities have been estimated for an important number of quantitative traits, mainly phenological times and fruit characters. Important information is available on molecular markers, including enzymes, RFLPs, RAPDs and other recently developed markers. Linkages, however, have only been established among molecular markers, allowing accurate genetic maps to be built but not yet enabling agronomical characters to be located in these maps, probably because the latter have not been sufficiently studied. The effectiveness of the application of genetic maps in plant breeding will depend on the accuracy of the study of different agronomic traits and their expression, implying more field work and recognition of this work. Ultimately, any new fruit cultivar has to be grown in the field and has to allow the grower to make a profit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220050777
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  • 159
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    Rescue FK506 early conversion for refractory rejection after pediatric liver transplantation: experience in 20 children (1998)
    Springer
    Transplant international 11 (1998), S. S272 
    Details
    ISSN: 1432-2277
    Keywords: Key words Liver transplantation ; Tacrolimus ; Human ; Child
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Tacrolimus (FK506) is an effective and relatively safe novel immunosuppressant able to revert refractory rejection after pediatric liver transplantation (LTx). Between April 1993 and October 1996, 20 pediatric patients were converted to tacrolimus for biopsy-proven, steroid-resistant liver rejection. The mean follow-up was 18 months. The median time from LTx to switch was 20 days. Tacrolimus was administered per os at a mean dosage of 0.23 mg/kg per day to maintain median blood levels of 10.8 ng/ml at 1 week and 9.2 ng/ml at 1 year from the switch. Of the 20 patients, 15 are alive and they all recovered from rejection without the need of OKT3 after conversion. The major causes of death were: one multiorgan failure, two infections (cytomegalovirus Aspergillus), one bowel perforation, and one posttransplant lymphoproliferative disease. One patient experienced late side effects and was reconverted to cyclosporine when she was already rescued from hepatic allograft rejection. The results confirm that an earlier conversion to tacrolimus should be recommended after pediatric liver transplantation in order to revert hepatic allograft rejection with the best safety profile.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001470050477
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  • 160
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    Division of labor between scouts and recruits: genetic influence and mechanisms (1998)
    Springer
    Behavioral ecology and sociobiology 43 (1998), S. 191-196 
    Details
    ISSN: 1432-0762
    Keywords: Key words Honeybees ; Scouting ; Division of labor ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Every recruitment system in social insects requires some individuals that serve as scouts, foragers that search independently for food sources. It is not well understood which factors influence whether an individual becomes a scout or a recruit, nor how the division of labor between the two forager groups is regulated. It is shown here for honeybees (Apis mellifera), using two different molecular techniques, that there is a genetically based difference in the probability that individuals will scout independently for food. In contrast to earlier suggestions, experimental tests showed that the age of a bee does not seem to influence its probability of becoming a scout or a recruit. Furthermore, scout bees do not search opportunistically for either pollen or nectar but, rather, individuals have preferences that are genetically based. These findings are discussed in the framework of foraging regulation by specialization in honeybees and the adaptive significance of polyandry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002650050480
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  • 161
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    Exocytosis in human salivary glands visualized by high-resolution scanning electron microscopy (1998)
    Springer
    Cell & tissue research 291 (1998), S. 325-336 
    Details
    ISSN: 1432-0878
    Keywords: Key words Salivary gland ; Secretion ; Granule docking ; Exocytosis-endocytosis coupling ; OsO4 maceration ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The luminal membrane of salivary acinar cells creates a specialized cell surface area that accepts exocytosis and undergoes dynamic changes during secretion. These changes were visualized three-dimensionally from both the inside and outside of the cell in human parotid and submandibular glands, by application of in vitro secretory stimulation and then of OsO4 maceration to remove cytoplasmic organelles by varying degrees. In control glands treated without secretagogues, the luminal surface of serous acinar cells bore well-developed microvilli with only an occasional incidence of exocytotic profiles. Following treatment with the β-adrenergic agonist, isoproterenol, considerable shortening and loss of microvilli occurred along the luminal membrane where, on its cytoplasmic side, many protuberances of sizes similar to or smaller than those of single secretory granules (∼1 μm in diameter) appeared. The cytoplasmic surface of these protuberances exhibited small vesicles (∼100–150 nm in diameter) that, by transmission electron microscopy, were shown to be coated pits or vesicles present on or around the exocytosed granule membranes. Treatment of tissues with the muscarinic agonist carbachol also caused a decrease of microvilli and the appearance of protrusions at the luminal membrane. However, unlike isoproterenol treatment, many of these protrusions were devoid of small pits or vesicles and were much larger than a single secretory granule. These results indicate that (1) secretory stimulation causes the dynamic transformation of microvilli at the luminal membrane, where granule docking and membrane fusion take place, and (2) after fusion, the exocytosed membranes are processed differently, by coated pit/vesicle mediated or non-mediated mechanisms, according to the autonomic receptor control.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051002
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  • 162
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    Monoclonal antibodies SMI 311 and SMI 312 as tools to investigate the maturation of nerve cells and axonal patterns in human fetal brain (1998)
    Springer
    Cell & tissue research 291 (1998), S. 433-443 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Neurofilaments ; Phosphorylation ; Differentiation ; Immunocytochemistry ; Brain storage ; Fixation ; Microwave ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Neurofilaments, which are exclusively found in nerve cells, are one of the earliest recognizable features of the maturing nervous system. The differential distribution of neurofilament proteins in varying degrees of phosphorylation within a neuron provides the possibility of selectively demonstrating either somata and dendrites or axons. Non-phosphorylated neurofilaments typical of somata and dendrites can be visualized with the aid of monoclonal antibody SMI 311, whereas antibody SMI 312 is directed against highly phosphorylated axonal epitopes of neurofilaments. The maturation of neuronal types, the development of area-specific axonal networks, and the gradients of maturation can thus be demonstrated. Optimal immunostaining with SMI 311 and SMI 312 is achieved when specimens are fixed in a mixture of paraformaldehyde and picric acid for up to 3 days and sections are incubated free-floating. Neurons, with their dendritic domains immunostained by SMI 311 in a Golgi-like manner, can be completely visualized in relatively thick sections. The limitations of Golgi-preparations, such as glia-labeling, artifacts, and the staining of only a small non-representative percentage of existing neurons, are not apparent in SMI preparations, which additionally provide the possibility of selectively staining axonal networks. The results achieved in normal fetal brain provide the basis for studies of developmental disturbances.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051013
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  • 163
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    Expression of insulin-like growth factor (IGF)-II in human prostate, breast, bladder, and paraganglioma tumors (1998)
    Springer
    Cell & tissue research 291 (1998), S. 469-479 
    Details
    ISSN: 1432-0878
    Keywords: Key words mRNA ; Cancerous epithelium ; Autocrine growth regulation ; In situ hybridization ; Immunohistochemistry ; Western blotting ; Benign prostate hyperplasia ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Insulin-like growth factors (IGFs) are potent mitogens for a variety of cancer cells in vitro. A paracrine/autocrine role of IGF-II in the growth of breast and prostate cancer cells has been suggested. Information on cell-type-specific IGF-II expression in vivo in the breast and prostate is, however, limited. Thus, cell types expressing IGF-II mRNA and protein in tumors were identified by in situ hybridization and immunohistochemistry. Of 36 prostate, 17 breast, and 10 bladder cancers, and 9 paraganglioma tissues examined, IGF-II was expressed in more than 50% of prostate, breast, and bladder tumors, and in 100% of paraganglioma tumors. Expression levels of IGF-II were highest in the paraganglioma and bladder followed by prostate and breast tumors. In all the tumors expressing IGF-II, both mRNA and protein were localized to malignant cells, expression in the stroma being minimal. Since previous studies had indicated that an incompletely processed form of 15-kDa IGF-II exhibited higher mitogenic potency than the completely processed 7.5-kDa IGF-II form, the quantity and size of IGF-II proteins expressed in these tumors were analyzed by Western immunoblotting. Greater expression of 15-kDa IGF-II relative to the 7.5-kDa IGF-II form was clearly demonstrated in all six prostate cancers and in half of the two breast and four bladder cancers examined. The results are consistent with the hypothesis that the 15-kDa form of IGF-II expressed in cancerous cells contributes to autocrine cancer cell growth in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051016
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  • 164
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    Effects of modulation of tyrosine phosphorylation on brush border enzyme activity in human Caco-2 intestinal epithelial cells (1998)
    Springer
    Cell & tissue research 292 (1998), S. 553-562 
    Details
    ISSN: 1432-0878
    Keywords: Key words Alkaline phosphatase ; Caco-2 intestinal epithelial cells ; Differentiation ; Dipeptidyl dipeptidase ; Proliferation ; Tyrosine kinase ; Tyrosine phosphoproteins ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Intestinal epithelial cell differentiation is closely regulated during normal cell renewal, maturation, and malignant transformation. Since tyrosine phosphorylation influences differentiation in other cell types and has been reported to vary between crypt cells to differentiated villus tip cells, we investigated the influence of tyrosine phosphorylation in colonocyte differentiation, by using human colonic Caco-2 cells as a model and expression of the brush border enzymes alkaline phosphatase (AKP) and dipeptidyl peptidase (DPDD) as differentiation markers. We studied three tyrosine kinase inhibitors with different modes of action and specificities, viz., genistein, erbstatin analog (EA), and tyrphostin, and the tyrosine phosphatase inhibitor sodium orthovanadate. AKP- and DPDD-specific activities were assayed in protein-matched cell lysates by synthetic substrate digestion. We also correlated the effects of these agents on brush border enzyme activity with tyrosine phosphorylation of phosphoproteins by Western blotting. Genistein (5–75 mg/ml) dose-dependently stimulated AKP and DPDD with a maximal stimulation at 75 mg/ml by 158.6± 17.5% and 228.6±37.1% of control values, respectively (n=12, P〈0.001). The inactive analog genistin had no effect. Tyrphostin (25 mM) similarly stimulated AKP and DPDD by 138.6±6.6% and 131.8±1.5% of control values (n=12, P〈0.001). Unexpectedly, EA (0.1–10 mM) had the opposite effect, inhibiting AKP- and DPDD-specific activity significantly at 10 mM with a maximal 14.8±6.4% and 26.5±2.5% of control values (n=12, each P〈0.001). Sodium orthovanadate had a discordant effect on these two differentiation markers. Orthovanadate dose-dependently increased AKP to a maximal 188.5±16.1% of basal activity at 1.5 mM but decreased DPDD activity at 1.5 mM to 47.2±3.8% (n=9, P〈0.001 each). The effects of each agent were preserved when proliferation was blocked with mitomycin C, suggesting that the modulation of phenotype by these agents was independent of any effects of proliferation. The tyrosine phosphorylation of several phosphoprotein bands was affected differently by these agents. In particular, the tyrosine phosphorylation of one 70-kDa to 71-kDa band was increased by genistein and tyrophostin but deceased by EA. The different effects of these modulators of tyrosine kinase activity raise the possibility that at least two independent enzymes or pathways regulating tyrosine phosphorylation modulate intestinal epithelial differentiation. Furthermore, tyrosine phosphorylation of the 70-kDa to 71-kDa phosphoprotein may be important in the intracellular signaling by which intestinal epithelial cell differentiation is controlled.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051084
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  • 165
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    The internal and external protein scaffold of the T-tubular system in cardiomyocytes (1998)
    Springer
    Cell & tissue research 294 (1998), S. 449-460 
    Details
    ISSN: 1432-0878
    Keywords: Key words Vinculin ; Talin ; Integrin ; Dystrophin ; Spectrin ; T-tubule ; Costamere ; Basal membrane ; Cardiac muscle cell ; Dilated cardiomyopathy ; Human ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The transverse tubule system of the cardiomyocyte remains undeformed despite the extreme forces it undergoes during the contraction-relaxation cycle, but the morphological basis for its stability remains unclear. Therefore, we have investigated the architecture and subcellular protein scaffold of the cardiac T-tubules and compared it with that of the costameres and of the free sarcolemma. Tissue samples from normal rat and monkey hearts, and left ventricular tissue from normal and cardiomyopathic human hearts obtained at transplantation surgery were investigated using immunocytochemistry and confocal microscopy and by electron microscopy. In addition, we used a re-differentiation model of isolated, cultured adult rat cardiomyocytes. The cell membrane of the cardiac T-tubules was found to contain the cell-matrix focal adhesion molecules (FAMs) vinculin, talin, the α5β1 integrin and the membrane-associated proteins (MAPs) dystrophin and spectrin. FAMs and MAPs were localized in the T-tubular membrane in a similar pattern: in longitudinally oriented myocytes as transverse punctate lines at the Z-level; in transversally cut myocytes a radial tubular network was found to extend throughout the interior of the cell. Immunolabeling for basement membrane components including collagen IV, fibronectin and laminin showed a colocalization with FAMs and MAPs parallel to the transverse T-tubules. The costameres of the sarcolemma showed a protein composition resembling that of the T-tubules but the intervening segments of free sarcolemma showed absence of FAMs and presence of MAPs. For the first time, we demonstrate the existence and protein composition of the T-tubular scaffold in the human heart. Furthermore, we show that cardiomyocytes from human failing hearts have less abundant but more dilated T-tubules than do experimental animals. These results indicate that the cardiac T-tubular system contains a subcellular scaffold closely resembling that of the costameres. It consists of FAMs, MAPs and basal lamina proteins that confer structural integrity to the cardiac T-tubular membrane during contraction/relaxation cycles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051196
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  • 166
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    Distribution and submicroscopic immunogold localization of cellular prion protein (PrPc) in extracerebral tissues (1998)
    Springer
    Cell & tissue research 292 (1998), S. 77-84 
    Details
    ISSN: 1432-0878
    Keywords: Key words Prion protein (PrPc) ; Electron microscopy ; Secretory granules ; Membrane ; Extracerebral tissues ; Hamster ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  In transmissible spongiform encephalopathies (TSE), such as scrapie in animals and Creutzfeldt-Jakob disease in humans, the central event is the conversion of a host-encoded amyloidogenic protein (PrPc) into an abnormal isoform (PrPsc) that accumulates as amyloid in TSE brain. PrPc is a membrane sialoglycoprotein synthesized in the central nervous system and elsewhere. We have examined the ultrastructural localization of PrPc in numerous hamster and some human extracerebral tissues, by means of a post-embedding electron-microscopic method combined with immunogold labeling. In stomach, intestine, lung, and kidney from hamsters, and in stomach, kidney, and spleen from humans, immunogold labeling specific for PrPc is observed on various cellular substructures related to secretory pathways: Golgi apparatus, secretory globules, and plasma membrane. In mucous epithelial cells of stomach and intestine, PrPc appears to be concentrated in secretory globules, suggesting a role for PrPc in the secretory function of the digestive tract. The secretory aspect of PrPc may be a key to understanding the physiopathological mechanisms underlying TSE.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051036
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  • 167
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    Broad immunocytochemical localization of the formylpeptide receptor in human organs, tissues, and cells (1998)
    Springer
    Cell & tissue research 292 (1998), S. 129-135 
    Details
    ISSN: 1432-0878
    Keywords: Key words Neurons ; Brain ; Chemotaxis ; Endothelial cells ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The formylpeptide receptor (FPR), previously found only on polymorphonuclear leukocytes and monocytes/macrophages, responds to both synthetic N-formyl oligopeptides and those produced by bacteria. The cDNA for human FPR has been cloned and a rabbit polyclonal antiserum directed against a synthetic 11-amino-acid peptide corresponding to the deduced carboxy-terminus has been produced. We have now extensively characterized and used the antibody to detect FPR on normal human tissues and cell types. The receptor antigen is present on some epithelial cells, especially those with a secretory function, and on some endocrine cells, e.g., follicular cells of the thyroid and cortical cells of the adrenal. Liver hepatocytes and Kupffer cells are positive. Smooth muscle and endothelial cells are also generally positive. In the brain and spinal cord, the neurons of the motor, sensory, and cerebellar systems, and those of the parasympathetic and sympathetic systems stain positively. These data suggest that the putative endogenous agonist for FPR or an antigenically similar receptor reacts with cellular targets in the neuromuscular, vascular, endocrine, and immune systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051042
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  • 168
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    Establishment of oral mucosa phenotype in vitro in correlation to epithelial anchorage (1998)
    Springer
    Cell & tissue research 292 (1998), S. 355-366 
    Details
    ISSN: 1432-0878
    Keywords: Key words Organotypic cocultures ; Histodifferentiation ; Proliferation ; Basement membrane components ; Integrins ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Cell-matrix interactions and the ordered deposition of basement membrane (BM) components are of major importance for the maintenance of tissue homeostasis in complex epithelia. This aspect was studied in vitro in a coculture system designed as an oral mucosa model. As crucial epithelial features the kinetics of proliferation, expression of site-specific keratins as well as integrin patterns in correlation to synthesis of BM components were assessed by immunohistochemistry and in situ hybridization. Comparison with non-cornified gingiva as tissue of origin revealed different stages of epithelial development, eventually leading to complete reconstruction within a time frame of 1–3 weeks. First, the initial activated stage up to 1 week was characterized by (a) high keratinocyte proliferation, (b) extended expression of the basal cell-specific keratin K5 and (c) a patchy pattern of the differentiation-specific keratins K4 and K13. Second, after 2 weeks the improvement of histoarchitecture correlated to (a) predominant K5 expression in the basal and (b) extension of K4 and K13 within the suprabasal cell compartment, (c) high expression of integrins α3β1 and α6β4 including their ligand laminin-5 and (d) accumulating deposition of basement membrane components. Third, virtually complete tissue normalization at 3 weeks was indicated by (a) restriction of K5 to the basal cell area, (b) regular suprabasal localization of K4 and K13, (c) polarization of integrins to basal and parabasal cells and (d) linear codistribution of collagen IV, “classical” laminin (-1 or -10) and laminin-5 underneath the basal cells. Thus, these organotypic cocultures represent relevant equivalents for non-keratinized oral mucosa with typical gingival differentiation features and in addition suitable models for preclinical trials such as prospective dental material testing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051066
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  • 169
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    Secretory cell types and cell proliferation of human bronchial epithelial cells in an organ-culture system (1998)
    Springer
    Cell & tissue research 293 (1998), S. 573-577 
    Details
    ISSN: 1432-0878
    Keywords: Key words Airways ; Mucins ; Secretion ; Mini-organ culture ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  To study the secretory products and the proliferation of cells of the human respiratory surface epithelium, we established a miniorgan-culture system of bronchial tissue. Biopsies of large airways were grown on agar-coated dishes immersed in a serum-enriched medium. As determined by light and transmission electron microscopy, between 1 and 3 weeks, the organ cultures were covered by a differentiated epithelium consisting of secretory, ciliated, and basal cells. Immunohistochemistry, using antibodies to mucin and lysozyme, and lectin histochemistry revealed both mucous and serous secretory cells in the epithelium. Cell proliferation was studied in situ using antibodies to proliferating cell nuclear antigen (PCNA) and Ki-67. Whereas at the time of explantation the proliferation was low (2.5±1.7% of the epithelial cells were PCNA-positive, 1.7±0.6 were Ki-67-positive), at 24 h of cultivation, 30.4±5.1% or 25.2±4.9% of the epithelial cells were labeled with antibodies to PCNA or Ki-67. After 7 days, the number of dividing cells was low again. The results show that the organ-culture system of human respiratory surface epithelium produces a differentiated epithelium that is useful in the study of secretory processes, differentiation, and proliferation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051150
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  • 170
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    Differential expression of type XIV collagen/undulin by human mammary gland intralobular and interlobular fibroblasts (1998)
    Springer
    Cell & tissue research 291 (1998), S. 507-511 
    Details
    ISSN: 1432-0878
    Keywords: Key words Mammary gland ; Type XIV collagen ; Undulin ; Fibroblast ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Immunolocalisation of type XIV collagen/undulin in the human mammary gland revealed greater deposition in the interlobular stroma than in the intralobular stroma. The interlobular stroma is located between the breast lobules and their associated intralobular stroma. Fibroblasts isolated from the interlobular stroma synthesised 3- to 5-fold more type XIV collagen/undulin than intralobular fibroblasts, but synthesised type I and type IV collagens in similar amounts. The differential expression of type XIV collagen/undulin was maintained with passage in culture. The results suggest a role for type XIV collagen/undulin in stabilising dense collagen fibrils. The maintenance of two types of structurally distinct stromas may be important during developmental processes in the mammary gland.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051020
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  • 171
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    Distribution of endoglin in early human development reveals high levels on endocardial cushion tissue mesenchyme during valve formation (1998)
    Springer
    Cell & tissue research 292 (1998), S. 333-343 
    Details
    ISSN: 1432-0878
    Keywords: Key words TGF-β ; TGF-β receptors ; Vascular endothelium ; Heart ; Vascular disorders ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Endoglin is a component of the receptor complex for transforming growth factor (TGF)-β1 and TGF-β3. We analysed its expression by immunohistochemistry in human embryos at 4–8 weeks of gestation and in hearts ranging from 4–13 weeks old. We compared endoglin distribution with that of TGF-β receptors type I (TβR-I), type II (TβR-II) and betaglycan. Endoglin was found on endothelial cells in all tissues examined, consistent with its expression in adult blood vessels. TβR-I, TβR-II and betaglycan were observed on most cell types and had an overall similar pattern of distribution. Endoglin was detected on the endocardium as early as 4 weeks, but was absent from myocardium. It was present at high levels on the endocardial cushion tissue mesenchyme from 5–8 weeks’ gestation, during heart septation and valve formation, and subsequently decreased as the valves matured. Endoglin expression in heart extracts was confirmed by Western blot analysis. TβR-I, TβR-II and betaglycan were mostly found on cardiac myocytes, but were detectable at low levels on endocardium. They were expressed transiently on cushion mesenchyme, albeit at much lower levels than endoglin. All four components of the TGF-β receptor complex were detected by RT-PCR in embryonic heart. Thus transient up-regulation of the components of the TGF-β receptor complex, and particulartly of endoglin, is associated with heart septation and valve formation during early human development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051064
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  • 172
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    Galα1→4Gal-glycans are expressed on myofibrillar associated proteins (1998)
    Springer
    Cell & tissue research 293 (1998), S. 285-291 
    Details
    ISSN: 1432-0878
    Keywords: Key words Muscle ; Masseter ; Biceps ; P blood group ; CD77 ; Galactose ; Cat ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  There is evidence that glycans carrying terminal galactose residues are differently expressed in the sarcoplasm of different muscle fiber types. In this study monoclonal antibodies directed against P blood group antigens Pk: Galα1–4Galβ1–4Glcβ- and P1: Galα1–4Galβ1–4GlcNAcβ- were used to detect terminal α-galactosylated glycoconjugates on muscle proteins. Electrotransfer of proteins, extracted from human masseter and biceps muscles, to nitrocellulose after polyacrylamide gel electrophoresis (PAGE) and incubation with anti-Pk (CD77) consistently showed two bands with apparent molecular weights of 66 kDa and 64 kDa. In fresh frozen muscle sections from some humans there was endothelial reaction with anti-CD77 in capillaries, venules and veins but not in arterioles and arteries. In muscle samples from other humans there was no staining of endothelial cells. Formalin-fixed human muscle displayed a CD77 reaction with highest accumulation of reaction product at the periphery of the fibers. This may be explained by the presence of Pk glycoconjugates on intermediate filaments in muscle fibers. In preparations of cat masseter muscle proteins the antibodies against P1Pk antigens reacted with a 170 kDa and a 55 kDa band while in preparations of cat biceps brachii only a 55 kDa band was reactive. The specificities of the antibodies were investigated by fluorescence-activated cell sorter (FACS), α- and β-galactosidase digestion and inhibitory sugars. This study indicates that glycans carrying Galα1–4Galβ1- epitopes are expressed on myofibrillar associated proteins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051120
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  • 173
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    Presence and location of endothelin and endothelin-binding sites in human nasal mucosa under normal and metaplastic conditions (1998)
    Springer
    Cell & tissue research 293 (1998), S. 509-516 
    Details
    ISSN: 1432-0878
    Keywords: Key words Nose ; Endothelin ; Respiratory epithelium ; Metaplastic epithelium ; Nasal blood flow ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The presence and site of production of endothelin-1 (ET-1) was investigated in biopsies obtained from the nasal mucosa of 10 healthy human subjects and 10 patients affected by chronic rhinitis. The presence and localization of receptors for ET-1 was also investigated. Bioptic fragments were examined by scanning electron microscopy. ET-1 was present in the vessels and in the respiratory epithelium of normal subjects, whereas in patients affected by epithelial metaplasia induced by chronic rhinitis, it was absent in the metaplastic epithelium and present in the endothelium and vascular wall. Receptors for ET (A- and B-receptor subtypes) were localized in the vessels of the nasal mucosa, both in normal and in pathological subjects. In particular, A-receptors were identified in the vascular wall, whereas B-receptors were mainly distributed in the endothelium. We suggest that ET-1 is involved in the homeostasis of nasal blood flow (shunting the blood toward the deep cavernous plexus and inducing mucosal swelling) by an autocrine and/or paracrine mechanism. Normal epithelium seems to be important in this mechanism, since it is able to produce ET. However, when pathologic conditions induce squamous or cuboidal metaplasia, the epithelium is no longer able to play this role.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051143
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  • 174
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    Electron-microscopical evidence for heterogeneity of micronodular argyrophil cell growth in man (1998)
    Springer
    Cell & tissue research 292 (1998), S. 91-99 
    Details
    ISSN: 1432-0878
    Keywords: Key words Argyrophil cells ; Chronic gastritis ; Gastrinoma/Zollinger-Ellison syndrome ; Hypergastrinaemia ; Neuroendocrine complexes ; Pernicious anaemia ; Proton pump inhibitors ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Hypergastrinaemia-associated changes of non-antral argyrophil cells in man are of increasing interest, because of the development of potent inhibitors of gastric acid secretion. Using an antibody against chromogranin A, we identified micronodular endocrine cell hyperplasia of the oxyntic mucosa in gastric biopsy specimens of patients with hypergastrinaemia of different backgrounds. Consecutive ultrathin sections were examined at the electron-microscopical level. Endocrine cell types within the (extraepithelial) micronodules closely resembled those in the adjacent mucosa. Micronodules were classified into two groups. The first group was composed of endocrine cells only and predominated in patients with drug-induced hypergastrinaemia and/or chronic gastritis, and in a gastrinoma/MEN I patient. The second group represented “neuroendocrine complexes”, showing a close intermingling of non-myelinated nerve fibres with endocrine cells, and was found predominantly in pernicious anaemia. Micronodular argyrophil cell growth in man is therefore heterogeneous and depends on the background of the hypergastrinaemia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051038
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  • 175
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    Temperature-sensitive regulation of epidermal morphogenesis and the expression of cornified envelope precursors by EGF and TGFα (1998)
    Springer
    Cell & tissue research 292 (1998), S. 107-114 
    Details
    ISSN: 1432-0878
    Keywords: Key words Reconstructed epidermis ; Differentiation ; Proliferation ; Migration ; Loricrin ; Involucrin ; SPRR ; EGF ; TGFα ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Epidermis reconstructed on de-epidermized dermis was used to investigate the effects of growth factors and culture temperature on epidermal morphogenesis and the expression of cornified envelope precursors. Cultures grown at 33°C or 37°C in the absence or presence of transforming growth factor alpha (TGFα), keratinocyte growth factor (KGF), basic fibroblast growth factor (bFGF), or insulin-like growth factor (IGF) show a similar morphology to that of native epidermis. Loricrin and SPRR2 are expressed in the stratum granulosum and SPRR3 is absent. Cultures grown in epidermal growth factor (EGF)-supplemented medium at 37°C have a normal morphology, whereas cultures grown at 33°C have a disorganized basal layer, no stratum granulosum, and nuclei are present in the stratum corneum. Loricrin is absent, and SPRR2 and SPRR3 expression extend into the spinous layers. Irrespective of the culture condition used, involucrin is aberrantly expressed in all suprabasal layers. EGF stimulated keratinocyte proliferation and migration to a greater degree than TGFα. Epidermis reconstructed on fibroblast-populated collagen gels at 33°C led to the same disturbances in keratinocyte differentiation as seen in cultures grown on de-epidermized dermis at 33°C in the presence of EGF, whereas parallel cultures grown at 37°C have a similar morphology to that of native epidermis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051040
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    Expression of SRY gene transcripts with a longer 3′ untranslated sequence in adult human male lymphocytes and tumor cells (1998)
    Springer
    Molecular genetics and genomics 257 (1998), S. 587-593 
    Details
    ISSN: 1617-4623
    Keywords: Key wordsSRY ; mRNA expression ; Human ; Lymphocytes ; Tumor ; Illegitimate transcripts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using 3′ RACE PCR and the repeated nested-PCR method, the expression of transcripts of the sex-determining gene SRY was investigated in single lymphocytes from a human adult male and in male tumor cell lines. The gene is functionally transcribed in the early stages of embryogenesis and mRNA is also expressed in adult testes. However, in this study, SRY gene transcripts were also detected in somatic cells of adult male and in tumor cells. Moreover, this mRNA possessed a longer additional untranslated exon. Although expression of the transcripts might not have any functional meaning in these cells, these new findings support the hypothesis that any given human cell can contain illegitimate mRNAs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004380050686
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    Neuronal ceroid lipofuscinoses: a review (1998)
    Springer
    Neurological sciences 19 (1998), S. 271-276 
    Details
    ISSN: 1590-3478
    Keywords: Neuronal ceroid lipofuscinosis ; Clinical features ; Classification ; Diagnosis ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Sommario Le ceroido lipofuscinosi neuronali (NCL) sono tra le encefalopatie progressive più freguenti nell'infanzia ed interessano, seppure più raramente, l'adulto. Clinicamente sono caratterizzate da demenza, deficit visivo, epilessia e disturbi motori. Gli aspetti patologici specifici sono rappresentati da degenerazione neuronale ed accumulo lisosomiale di lipopigmento in differenti tipi cellulari. Il difetto biochimico della malattia non e noto. La classificazione delle NCL, basata su criteri clinici, distingue sei forme classiche ed altre forme atipiche. L'elettrofisiologia e la neuroradiologia sono di importante ausilio diagnostico, ma la diagnosi si fonda sull'identificazione dell'accumulo di lipopigmento the presenta pattern ultrastrutturali specifici. Differenti difetti genetici sono stati dimostrati in diverse forme cliniche, ma il meccanismo patogenetico molecolare rimane ancora da chiarire.
    Notes: Abstract Neuronal ceroid lipofuscinoses (NCLs) are among the most common neurodegenerative diseases in childhood but rarely present in adulthood. The main symptoms are psychomotor deterioration, visual failure, epilepsy and motor disturbances. The NCLs are morphologically characterized by the accumulation of lipopigments within numerous cell types and loss of neurons. Pathogenesis is unknown. The current clinical classification recognizes six classic types of NCL and several atypical forms. Electrophysiological and neuroradiological findings may be of diagnostic significance, but disease recognition rests on the demonstration of a typical ultrastructural pattern. Genetic studies have demonstrated that several different genetic loci are involved in the pathogenesis of NCL, but the molecular mechanisms underlying neuronal death and lipopigment accumulation are not understood.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00713852
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    Trends in mortality from major diseases in Europe, 1980–1993 (1998)
    Springer
    European journal of epidemiology 14 (1998), S. 1-8 
    Details
    ISSN: 1573-7284
    Keywords: Europe ; Geographical ; Human ; Mortality ; Neoplasms ; Temporal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Trends in age-standardized death certification rates from all causes, coronary heart disease (CHD), cerebrovascular diseases, all neoplasms and lung cancer were analysed over the period 1980–1993 in 20 major European countries. There were steady and substantial declines of overall mortality in all western European countries for both sexes, although appreciable geographic differences persisted. These favourable trends reflect a decline in CHD mortality in most western countries, besides a persisting fall in cerebrovascular disease, and a substantial stability (with some decline in a few northern and central European countries) in cancer mortality. In contrast, in eastern European countries appreciable rises were registered in mortality from major causes of death considered for males. For females, only moderate declines were observed in Eastern Europe. In the early 1990s, overall mortality was 30 to 100% higher for males and 20 to 100% higher for females as compared to Western Europe. As indicated by the trends in lung cancer death rates, this reflects a major impact of the tobacco-related disease epidemic in subsequent cohorts, as well as more unfavourable lifestyle factors (i.e. aspects of diet, other environmental factors), and a delayed control of hypertension in Eastern Europe, together with a substantial excess of suicides, (road) accidents, homicides and alcohol-related diseases, and the delayed introduction of rational treatment for some conditions. An indication of reversal of mortality trends was evident in the early 1990s only in Poland. In conclusion, there is ample scope for intervention on avoidable mortality in eastern European countries.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007440201137
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  • 179
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    Genetic and Shared Environmental Influences on Adolescent BMI: Interactions with Race and Sex (1998)
    Springer
    Behavior genetics 28 (1998), S. 265-278 
    Details
    ISSN: 1573-3297
    Keywords: Genetics ; body mass index ; adolescents ; race ; sex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Psychology
    Notes: Abstract The present study uses a behavioral genetic design to investigate the genetic and environmental influences on variation in adolescent body mass index (BMI) and to determine whether the relative influences of genetic and environmental factors on variation in BMI are similar across racial groups and sexes. Data for the present study come from the National Longitudinal Study on Adolescent Health (Add Health), a large, nationally representative study of adolescent health and health-related behaviors. The Add Health sample contains a subset of sibling pairs that differs in levels of genetic relatedness, making it well suited for behavioral genetics analyses. The present study examines whether genetic and environmental influences on adolescent BMI are the same for males and females and for Black and White adolescents. Results indicate that genetic factors contribute substantially to individual differences in adolescent BMI, explaining between 45 and 85% of the variance in BMI. Furthermore, based on an analysis of opposite-sex sibling pairs, the genes that influence variation in adolescent BMI are similar for males and females. However, the relative importance of genetic and environmental influences on variation in BMI differs for males and females and for Blacks and Whites. Although parameter estimates could be constrained to be equal for Black and White males, they could not be constrained to be equal for Black and White females. Moreover, the best-fitting model for Black females was an ADE model, for White females it was an ACE model, and for males it was an AE model. Thus, shared environmental influences are significant for White female adolescents, but not for Black females or males. Likewise, nonadditive genetic influences are indicated for Black females, but not for White females or males. Implications of these results are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021619329904
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    The possibilities of modeling neural networks in the framework of the thermodynamics of genetically disordered systems (glasses) (1998)
    Springer
    Journal of biological physics 24 (1998), S. 41-58 
    Details
    ISSN: 1573-0689
    Keywords: Neural networks ; Associative memory ; Brain functions ; Disordered systems ; Genetics ; Synergetics ; Self-organization ; Vitreous state
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Non-spin glasses possess a number of specific features which, in structural and dynamic aspects, are close to conditions necessary for neural networks to function. In a disordered network there exists a plurality of structural parameters and a number of two-level states defined by double-well potentials. Their characteristics are specified by the conditions of glass formation, i.e. by genesis. The thermodynamic description of glass as a self-organizing system (that does not require introducing an interacting potential model) leads to an unambiguous conclusion that its frequency spectrum is predetermined by the structure, which is characterized by zero-point entropy. Glass is a natural system of oscillators which form a disordered network. In this sense, glass conforms to a known model of a disordered neural network formed by interconnected oscillators. If one assumes that in living organisms the structure of a neural network (the brain) is inherited according to a genetic mechanism, the quickness of learning and recognition of patterns, the stability of associative memory and other capabilities have to be inherited genetically. The more ordered a neural network formed by distinguishable neurons, the better its capabilities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005071706864
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    Molecular Genetic Investigations of Autism (1998)
    Springer
    Journal of autism and developmental disorders 28 (1998), S. 427-437 
    Details
    ISSN: 1573-3432
    Keywords: Genetics ; autism ; genotyping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Psychology
    Notes: Abstract Genetic factors are likely to play a major role in the etiology of autism. The genetics of the disorder is however complex, probably involving the action of several genes. In an attempt to identify autism susceptibility loci we are currently undertaking a systematic screening of the whole human genome using multiplex families. We describe the resources and the methods needed to achieve such a task, including extensive collection of family data, semiautomated genotyping technology, and specialized statistical approaches for linkage analysis of complex traits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026056522602
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    Effects of nerve growth factor and glucocorticoid on cultured human pheochromocytoma cells (1998)
    Springer
    Medical molecular morphology 31 (1998), S. 24-30 
    Details
    ISSN: 1860-1499
    Keywords: Human ; Pheochromocytoma ; Nerve growth factor ; Cultured cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Primary cell cultures of two human pheochromocytomas (PC) that were associated with high serum levels of adrenaline and noradrenaline were developed to study the effects of nerve growth factor (NGF) and dexamethasone on the morphology and function of PC cells in vitro. By phase-contrast microscopy, cultured cells were small and hyperchromatic on the first day of culture; neurite-like processes that extended to other cells developed several days later and were maintained for more than 3 months. NGF (100ng/ml), dexamethasone (10−5M), or NGF + dexamethasone were added to the culture media 2 weeks after the cultured cells had stabilized. Catecholamine concentrations in the medium were maintained at higher levels after addition of NGF, dexamethasone, or NGF + dexamethasone as compared to control cells. In the presence of NGF, extension of neurite-like processes was clearly accelerated, while high levels of dexamethasone inhibited growth of processes. These in vitro studies showed that the addition of NGF or the removal of dexamethasone induces differentiation of adrenal neurons present in pheochromocytomas, suggesting that adrenocortical steroid hormones influence the morphological control of adrenal medullary cells.
    Type of Medium: Electronic Resource
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    The SPL1 tRNA splicing gene of Candida maltosa and Candida albicans (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 14 (1998), S. 287-295 
    Details
    ISSN: 0749-503X
    Keywords: Candida maltosa ; Candida albicans ; tRNA splicing gene ; silent genes ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The tRNA splicing gene SPL1-1 has been cloned and sequenced in Saccharomyces cerevisiae (Kolman and Soll, 1993). Sequence adjacent to the LEU2 gene in Candida maltosa showed some homology to the SPL1-1 gene of S. cerevisiae. This work describes the sequencing of the SPL1 tRNA splicing genes from C. maltosa and C. albicans and the analysis of these genes. Comparison of these sequences and the relationship observed between the LEU2 and SPL1 genes in these yeasts suggests that there may be some synteny amongst various species of yeasts. The coding region of the C. maltosa SPL1 region described in this work differs from previously described partial sequences in that it is a complete uninterrupted open reading frame. Two strains of C. maltosa were each shown to contain different alleles, one uninterrupted open reading frame and one disrupted open reading frame. The sequences have been deposited in the GenBank/EMBL data libraries under Accession Numbers X72940, AF000115, AF000116, AF000117, AF000118, AF000119 and AF000120. © 1998 John Wiley & Sons, Ltd.
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    Isolation and characteristics of yeasts able to grow at low concentrations of nutrients (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 14 (1998), S. 233-238 
    Details
    ISSN: 0749-503X
    Keywords: Oligotrophic yeasts ; low-nutrient conditions ; starvation ; Cryptococcaceae ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Seven oligotrophic yeasts, which can grow in a 104-fold dilution of malt-yeast-glucose-peptone medium (10-4 YM), were mainly isolated from soil. These yeasts belong to the Cryptococcaceae. When inoculated at about 102 cells/ml in 10-4 YM, the isolates grew to 1·4×103-2·4×105 cells/ml after 3 days. Some culture collection yeasts fell into three groups according to their growth characteristics in 10-4 YM, one group showing characteristics of the oligotrophic yeasts. The half-saturation values of uptake by the five isolated oligotrophic yeasts for D-glucose, L-leucine and L-amino acids were 6·0-25·0, 1·7-43·3 and 3·5-21·6 μM, respectively. The oligotrophic yeasts suspended in 10 mM-phosphate buffer (pH 6·0) had high tolerances for starvation, and remained more than 15% viable after 90 days of starvation. © 1998 John Wiley & Sons, Ltd.
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    Mam33p, an oligomeric, acidic protein in the mitochondrial matrix of Saccharomyces cerevisiae is related to the human complement receptor gC1q-R (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 14 (1998), S. 303-310 
    Details
    ISSN: 0749-503X
    Keywords: Saccharomyces cerevisiae ; mitochondria ; mitochondrial matrix ; homo-oligomeric protein ; Mam33p ; gene disruption ; gC1q-R ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Mam33p (mitochondrial acidic matrix protein) is a soluble protein, located in mitochondria of Saccharomyces cerevisiae. It is synthesized as a precursor with an N-terminal mitochondrial targeting sequence that is processed on import. Mam33p assembles to a homo-oligomeric complex in the mitochondrial matrix. It can bind to the sorting signal of cytochrome b2 that directs this protein into the intermembrane space. Mam33p is encoded by an 801 bp open reading frame. Gene disruption did not result in a significant growth defect. Mam33p exhibits sequence similarity to gC1q-R, a human protein that has been implicated in the binding of complement factor C1q and kininogen. © 1998 John Wiley & Sons, Ltd.
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    Assembly of phosphofructokinase-1 from Saccharomyces cerevisiae in extracts of single-deletion mutants (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 14 (1998), S. 323-334 
    Details
    ISSN: 0749-503X
    Keywords: phosphofructokinase-1 ; Saccharomyces cerevisiae ; deletion mutants ; reactivation ; assembly ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Phosphofructokinase-1 from Saccharomyces cerevisiae is an octameric enzyme comprising two non-identical subunits, α and β, which are encoded by the unlinked genes PFK1 and PFK2. In this paper, assembly and reactivation of the enzyme have been studied in cell-free extracts of single-deletion mutants. In contrast to the previously described lack of phosphofructokinase-1 activity in cell-free extracts of these mutants, we could measure a temporary enzyme activity immediately after lysis of protoplasts. This result supports the assumption that each of the subunits forms an enzyme structure which is active in vivo but not stable after cell disruption.Upon mixing of separately prepared cell-free extracts of both deletion mutants very low activity could be measured. About 40% of the wild-type activity was regained when both mutants were mixed prior to disruption. The reactivation rate could be slightly increased by addition of ATP and fructose 6-phosphate and was found to be a function of the growth state, particularly of the β-subunit-carrying cells. The individual subunits did not interact with Cibacron Blue F3G-A, a biomimetic ligand of phosphofructokinase-1. After reassembly of both subunits in vitro a strong affinity of the reconstituted phosphofructokinase-1 to the dye-ligand was observed.The inability of the subunits to reconstitute under certain conditions seems to result from alterations of the intracellular environment following disruption. These changes give rise to induce an unproductive side reaction like self-aggregation of the subunits.Because reconstitution of phosphofructokinase-1 from S. cerevisiae behaves in a similar way to that of hemoglobin and luciferase, we would speculate a general mechanism for assembly of oligomeric proteins in vivo. © 1998 John Wiley & Sons, Ltd.
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    The importance of the glycerol 3-phosphate shuttle during aerobic growth of Saccharomyces cerevisiae (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 14 (1998), S. 347-357 
    Details
    ISSN: 0749-503X
    Keywords: Saccharomyces ; redox ; glycerol ; NADH ; shuttle ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Maintenance of a cytoplasmic redox balance is a necessity for sustained cellular metabolism. Glycerol formation is the only way by which Saccharomyces cerevisiae can maintain this balance under anaerobic conditions. Aerobically, on the other hand, several different redox adjustment mechanisms exist, one of these being the glycerol 3-phosphate (G3P) shuttle. We have studied the importance of this shuttle under aerobic conditions by comparing growth properties and glycerol formation of a wild-type strain with that of gut2Δ mutants, lacking the FAD-dependent glycerol 3-phosphate dehydrogenase, assuming that the consequent blocking of G3P oxidation is forcing the cells to produce glycerol from G3P. To impose different demands on the redox adjustment capability we used various carbon sources having different degrees of reduction.The results showed that the shuttle was used extensively with reduced substrate such as ethanol, whereas the more oxidized substrates lactate and pyruvate, did not provoke any activity of the shuttle. However, the absence of a functional G3P shuttle did not affect the growth rate or growth yield of the cells, not even during growth on ethanol. Presumably, there must be alternative systems for maintaining a cytoplasmic redox balance, e.g. the so-called external NADH dehydrogenase, located on the outer side of the inner mitochondrial membrane. By comparing the performance of the external NADH dehydrogenase and the G3P shuttle in isolated mitochondria, it was found that the former resulted in high respiratory rates but a comparably low P/O ratio of 1·2, whereas the shuttle gave low rates but a high P/O ratio of 1·7.Our results also demonstrated that of the two isoforms of NAD-dependent glycerol 3-phosphate dehydrogenase, only the enzyme encoded by GPD1 appeared important for the shuttle, since the enhanced glycerol production that occurs in a gut2Δ strain proved dependent on GPD1 but not on GPD2. © 1998 John Wiley & Sons, Ltd.
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    Construction of PCR-ligated long flanking homology cassettes for use in the functional analysis of six unknown open reading frames from the left and right arms of Saccharomyces cerevisiae chromosome XV (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 14 (1998), S. 391-399 
    Details
    ISSN: 0749-503X
    Keywords: modified LFH cassette ; EUROFAN 6-pack analysis ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Six open reading frames (ORFs) of unknown function from Saccharomyces cerevisiae chromosome XV, three from the left and three from the right arm, were deleted in two diploid strains by the short flanking homology method (Wach et al., 1994). Transformants were selected as Geneticin (G418)-resistant colonies and correct integration of the kanMX4 cassette was checked by colony PCR. Following sporulation of the diploids, tetrads were dissected and scored for the segregation of the G418-resistant marker. We have developed a widely applicable method for the construction of gap repair plasmids to obtain the cognate clones for each of the disrupted ORFs. The 5′- and 3′-flanks of the ORF in question are linked by a unique restriction endonuclease. When the plasmid is cut at this site it can be used to obtain, by selection for the appropriate antibiotic resistance, long flanking homology (LFH) cassettes containing the cognate clone or the disrupted allele. The LFH cassette containing the cognate clone or the disrupted allele can be released from the gap-repaired plasmid by cutting at the inserted flanking restriction sites. One of the six ORFs (YOR319w) corresponds to an essential gene whose product is part of the spliceosome complex. Haploid as well as homozygous and heterozygous diploid disruptant strains for each of the five non-essential ORFs were subjected to growth test on different media at 15°C, 30°C and 37°C. Disruption of YOR322c causes osmotically sensitive growth on YEPD at 37°C and the product of YOL091w appears to play a role in sporulation since the homozygous diploid disruptant has lost the ability to sporulate. © 1998 John Wiley & Sons, Ltd.
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    Identification and analysis of homologues of Saccharomyces cerevisiae Spt3 suggest conserved functional domains (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 14 (1998), S. 409-417 
    Details
    ISSN: 0749-503X
    Keywords: transcription factor ; SPT3 sequences ; Schizosaccharomyces pombe ; Kluyveromyces lactis ; Clavispora opuntiae ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Spt3 of Saccharomyces cerevisiae is a factor required for normal transcription from particular RNA polymerase II-dependent promoters. As a step towards analysing Spt3 structure-function relationships, we have identified and studied Spt3 homologues from three other yeasts: Kluyveromyces lactis, Clavispora opuntiae and Schizosaccharomyces pombe. Alignment of their predicted amino acid sequences shows an overall identity of 30% between all four homologues and suggests that three conserved domains are present in Spt3. When tested for function in S. cerevisiae, K. lactis SPT3 was shown to fully complement and S. pombe SPT3 to partially complement an spt3 Δ mutation. These data demonstrate that Spt3 is functionally conserved among distantly related yeasts. The new sequences have been entered in GenBank: AF005930 (K. lactis SPT3), AF005932 (C. opuntiae SPT3) and AF005931 (S. pombe SPT3). © 1998 John Wiley & Sons, Ltd.
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    The list of cytoplasmic ribosomal proteins of Saccharomyces cerevisiae (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 14 (1998), S. 471-477 
    Details
    ISSN: 0749-503X
    Keywords: ribosomal protein genes ; yeast genome ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Screening of the complete genome sequence from the yeast Saccharomyces cerevisiae has enabled us to compile a complete list of the genes encoding cytoplasmic ribosomal proteins in this organism.Putative ribosomal protein genes were selected primarily on the basis of the sequence similarity of their products with ribosomal proteins from other eukaryotic organisms, in particular the rat. These genes were subsequently screened for typical yeast rp-gene characteristics, viz. (1) a high codon adaptation index; (2) their promoter structure and (3) their responses to changes in growth conditions.The yeast genome appears to carry 78 different genes, of which 59 are duplicated, encoding 32 different small-subunit and 46 large-subunit proteins. A new nomenclature for these ribosomal proteins is proposed. © 1998 John Wiley & Sons, Ltd.
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    Purified arginine permease of Candida albicans is functionally active in a reconstituted system (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 14 (1998), S. 335-345 
    Details
    ISSN: 0749-503X
    Keywords: Candida albicans ; arginine permease ; amino acid transport ; affinity chromatography ; functional reconstitution ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have for the first time purified arginine permease from a pathogenic yeast, Candida albicans, to homogeneity by affinity chromatography using L-arginine-linked agarose matrix as affinity column. The purified protein (PP) was of 66 kDa with no subunit structure. Two kinetically distinct binding affinities of PP were evident where high affinity binding (S1) revealed a dependence on acidic pH while pH did not have dramatic effect on low affinity (S2) binding. The specificity of L-arginine binding to PP with regard to other amino acids, structural analogues and inhibitors, was essentially similar to arginine transport observed in the intact cells of C. albicans (Rao et al., 1986). The purified arginine permease was reconstituted into proteoliposomes and its functionality was tested by imposing a valinomycin-induced membrane potential. All the characteristic features of L-arginine transport displayed by the reconstituted system were similar to those observed in intact cells. Thus homogeneous purified arginine permease was also functionally active. © 1998 John Wiley & Sons, Ltd.
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    Purification and properties of polyphosphatase from Saccharomyces cerevisiae cytosol (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 14 (1998), S. 383-390 
    Details
    ISSN: 0749-503X
    Keywords: polyphosphatase ; cytosol ; yeast ; purification ; kinetic model ; Mg2+ ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A homogenous polyphosphatase preparation was obtained from Saccharomyces cerevisiae cytosol with a 3·8% yield and 3540-fold purification. The enzyme hydrolysed polyphosphate (polyP) with various chain lengths, including polyP3, and split Pi off the end of the chain. It was inactive with respect to ATP, PPi, and p-nitrophenylphosphate. Its specific activity with polyP15 was 283 U/mg protein. The polyphosphatase was a monomeric protein with a molecular mass of 40 kDa. This enzyme was inactive without divalent cations and with Cu2+ and Ca2+. The ability of other divalent cations to activate the enzyme decreased in the following order: Co2+〉Mn2+〉Mg2+〉Zn2+. A kinetic model of the hydrolysis of polyP3 and action of Mg2+ is proposed. © 1998 John Wiley & Sons, Ltd.
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    Isolation and characterization of Kluyveromyces marxianus mutants deficient in malate transport (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 14 (1998), S. 401-407 
    Details
    ISSN: 0749-503X
    Keywords: yeast ; Kluyveromyces marxianus ; malic acid transport ; mutants ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In malic acid-grown cells of the strains ATCC 10022 and KMS3 of Kluyveromyces marxianus the transport of malic acid occurred by a malate-proton symport, which accepted l-malic, d-malic, succinic and fumaric acids, but not tartaric, malonic or maleic acids. The system was inducible and subjected to glucose repression. Mutants of the strain KMS3, unable to grow in a medium with malic acid, were isolated and checked for their capacity to utilize several carbon sources and to transport dicarboxylic acids by the malate-proton symport. Two distinct clones affected on malate transport were obtained. Both were able to grow on a medium with glycerol or ethanol but not with dl-malic, succinic, oxoglutaric and oxaloacetic acids as the sole carbon and energy sources. However, while one of the mutants (Mal7) displayed activity levels for the enzymes malate dehydrogenase, isocitrate lyase, and phosphoenolpyruvate carboxykinase similar to those of the wild strain, in the other mutant type (Mal6) the activities for the same enzymes were significantly reduced. Plasma membranes from derepressed cells of the wild strain and of the mutants Mal6 and Mal7 were isolated and the protein analysed by SDS-PAGE. The electrophoretic patterns of these preparations differed in a polypeptide with an apparent molecular mass of about 28 kDa, which was absent only in the mutant Mal7. The results indicated that Mal7 can be affected in a gene that encodes a malate carrier in K. marxianus. © 1998 John Wiley & Sons, Ltd.
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    Characterization of the Prk1 protein kinase from Schizosaccharomyces pombe (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 14 (1998), S. 485-492 
    Details
    ISSN: 0749-503X
    Keywords: Schizosaccharomyces pombe ; protein kinase ; cell flocculation ; PRK1 ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We report the isolation and characterization of a protein kinase from the fission yeast Schizosaccharomyces pombe. The proposed Prk1 protein contains 352 amino acids and has significant homology to the Ume5p kinase (also known as Srb10p, Ssn3p and Are1p) of the budding yeast Saccharomyces cerevisiae, a cyclin-dependent kinase involved in regulating the transcription of a diverse set of genes. Disruption of the prk1 gene increases flocculation but does not appear to have any other significant effect on cell behaviour. This defect can be overcome by expressing the UME5 gene, indicating that Prk1 is the fission yeast homologue of Ume5p. The sequence is in the EMBL data library under Accession Number Z98977. © 1998 John Wiley & Sons, Ltd.
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    Application of mRNA differential display to investigate gene expression in thermotolerant cells of Saccharomyces cerevisiae (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 14 (1998), S. 431-442 
    Details
    ISSN: 0749-503X
    Keywords: differential display ; S.cerevisiae ; thermotolerance ; repression ; derepression ; gene regulation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have described the use of differential display of PCR-amplified reverse transcribed mRNA (DDRT-PCR) to survey changes in gene expression profiles induced by heat shock and carbon catabolite derepression in Saccharomyces cerevisiae. It is well established that either of these states elicits thermotolerant phenotypes. An initial analysis conducted on cells of an inherently thermosensitive strain (Ysen) indicated that approximately 10% of the total number of cDNAs detected were either up or down regulated following heat shock at 37°C (30 min) in comparison to control cells (25°C). In addition, whereas 7% of all PCR products were preferentially expressed during derepressive growth, approximately 2% were found to be common to both heat-shocked and derepressed cells. A repeat analysis, performed on all three cell types of Ysen as well as cells of a relatively thermoresistant strain (Yres) yielded 30 differentially displayed cDNA fragments common to heat-shocked and derepressed cells of both strains. Eighteen of these generated signals on Northern blots, of which three were confirmed as regulated. Five amplicons, including one not detected by Northern analysis and another from the derepressed state, were cloned and sequenced. Three of these exhibited homology to S. cerevisiae genes with well-characterized protein products: HSP 90, HXK1and STA1. The remaining two applicons showed nucleotide identity to YTIS11, a homolog of the mammalian TIS11 and putative transcriptional activator, and an orphan gene encoding a hypothetical transmembrane protein belonging to the multi-drug resistance translocase family. Our novel application of DDRT-PCR has identified new and known genes that may be further evaluated as factors involved in stress regulation and has demonstrated the potential of the technique to systematically analyse gene expression in yeast. © 1998 John Wiley & Sons, Ltd.
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    Homolog of a-factor receptor gene in Saccharomyces exiguus (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 14 (1998), S. 583-586 
    Details
    ISSN: 0749-503X
    Keywords: Saccharomyces exiguus ; STE3 ; homolog ; sequence analysis ; differentiation of species ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Homologs of Saccharomyces cerevisiae STE3, a-factor receptor gene were detected from S. exiguus NFRI 3539 by low stringency Southern hybridization. This strain might have at least two types of homolog. One of these homologs, designated as e-STE3 was cloned. Its nucleotide sequence revealed 60% identity to STE3. The putative protein coding region consisted of 453 amino acid residues. The amino acid sequence identity between STE3 and e-STE3 was 62%, and that of the N-terminal 303 amino acid residues considered to be the pheromone binding domain was 79%. The e-STE3 sequence submitted to the DDBJ/EMBL/GenBank data libraries is available under Accession Number AB003086. © 1998 John Wiley & Sons, Ltd.
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    An improved protocol for the preparation of yeast cells for transformation by electroporation (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 14 (1998), S. 565-571 
    Details
    ISSN: 0749-503X
    Keywords: Saccharomyces cerevisiae ; electroporation ; transformation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Pretreatment of yeast cells with lithium acetate (LiAc) and dithiothreitol (DTT) enhances the frequency of transformation by electroporation. The method shows improvements of 6-67-fold in wild-type strains derived from commonly used Saccharomyces cerevisiae genetic backgrounds. In addition, 15-300-fold improvement in transformation frequency was achieved with several mutant strains of S. cerevisiae that transformed poorly by conventional procedures. Both DTT and lithium acetate were necessary for maximal transformation frequencies. Pretreatment with lithium and DTT also resulted in an ∼3·5-fold increase in the electroporation transformation frequency of the pathogenic fungus Candida albicans. © 1998 John Wiley & Sons, Ltd.
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    Deletion of transmembrane domain 12 of CDR1, a multidrug transporter from Candida albicans, leads to altered drug specificity: Expression of a yeast multidrug transporter in baculovirus expression system (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 14 (1998), S. 535-550 
    Details
    ISSN: 0749-503X
    Keywords: multidrug resistance ; CDR1 ; ABC transporter ; baculovirus expression ; C. albicans ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Cdr1p, an ATP-binding cassette transporter from the pathogenic yeast Candida albicans, confers resistance to several unrelated drugs including anti-Candida drugs (Prasad et al., 1995b). We demonstrate that the deletion of 237 bp (79 aa) from the 3′ end of CDR1 (which encompasses the transmembrane domain (TM) 12 of the putative transporter) did not result in the total loss of its ability to efflux cytotoxic agents. While the expression of ΔCDR1 in yeast resulted in impaired sensitivity to drugs like cycloheximide, anisomycin, sulfomethuron methyl and antifungal nystatin, its ability to confer resistance remained unaltered to drugs such as o-phenanthroline, 4-nitroquinoline-N-oxide, cerulenin, azoles, oligomycin, erythromycin, and benomyl. Similar to human MDR1p, Cdr1p might also have localized drug binding sites in TM 12, but that might not be the case for all the drugs. The TM 12 deletion also did not lead to any significant impairment in NTPase activities. Both ATPase and UTPase activities of complete Cdr1p and ΔCdr1p were not significantly altered, as was the case with respect to their ability to efflux Rh123 and steroid hormone like [3H]-β-estradiol. To further dissect the functionality of Cdr1p, its truncated version was overexpressed in a baculovirus-insect cell expression system. The synthesis of ΔCdr1p in Sf9 cells was temporally regulated as a function of the baculovirus polyhedrin gene promoter. The Sf9 derived ΔCdr1p was ∼130 kDa, which was lower than the expected size, probably due to the differences in glycosylation. This, however, did not affect the functionality of ΔCdr1p. The deletion of TM 12 did not affect the targeting of the protein and ΔCdr1p was exclusively localized in plasma membrane of Sf9 cells as detected by immunofluorescence. The expression of ΔCdr1p in the baculovirus-insect expression system generated a high drug-stimulated plasma membrane-bound ATPase activity which was not demonstrable when ΔCdr1p was expressed in yeast. © 1998 John Wiley & Sons, Ltd.
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    Identification and characterization of the KlCMD1 gene encoding Kluyveromyces lactis calmodulin (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 14 (1998), S. 869-875 
    Details
    ISSN: 0749-503X
    Keywords: calmodulin ; CMD1 ; ALG1 ; K. lactis ; EF hand ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The KlCMD1 gene was isolated from a Kluyveromyces lactis genomic library as a suppressor of the Saccharomyces cerevisiae temperature-sensitive mutant spc110-124, an allele previously shown to be suppressed by elevated copy number of the S. cerevisiae calmodulin gene CMD1. The KlCMD1 gene encodes a polypeptide which is 95% identical to S. cerevisiae calmodulin and 55% identical to calmodulin from Schizosaccharomyces pombe.Complementation of a S. cerevisiae cmd1 deletion mutant by KlCMD1 demonstrates that this gene encodes a functional calmodulin homologue. Multiple sequence alignment of calmodulins from yeast and multicellular eukaryotes shows that the K. lactis and S. cerevisiae calmodulins are considerably more closely related to each other than to other calmodulins, most of which have four functional Ca2+-binding EF hand domains. Thus like its S. cerevisiae counterpart Cmd1p, the KlCMD1 product is predicted to form only three Ca2+-binding motifs. The KlCMD1 sequence has been assigned Accession Number AJ002021 in the EMBL/GenBank database. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 200
    Electronic Resource
    Electronic Resource
    ARH1 of Saccharomyces cerevisiae: A new essential gene that codes for a protein homologous to the human adrenodoxin reductase (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 14 (1998), S. 839-846 
    Details
    ISSN: 0749-503X
    Keywords: Saccharomyces cerevisiae ; adrenodoxin reductase ; mitochondria ; essential gene ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A yeast gene was found in which the derived protein sequence has similarity to human and bovine adrenodoxin reductase (Nobrega, F. G., Nobrega, M. P. and Tzagoloff, A. (1992). EMBO J. 11, 3821-3829; Lacour, T. and Dumas, B. (1996). Gene 174, 289-292), an enzyme in the mitochondrial electron transfer chain that catalyses in mammals the conversion of cholesterol into pregnenolone, the first step in the synthesis of all steroid hormones. It was named ARH1 (Adrenodoxin Reductase Homologue 1) and here we show that it is essential. Rescue was possible by the yeast gene, but failed with the human gene. Supplementation was tried without success with various sterols, ruling out its involvement in the biosynthesis of ergosterol. Immunodetection with a specific polyclonal antibody located the gene product in the mitochondrial fraction. Consequently ARH1p joins the small group of gene products that affect essential functions carried out by the organelle and not linked to oxidative phosphorylation. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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