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Biomedical subjects

P Zangger

Publications and source records attributed to P Zangger.

14 recordsLinked to original sources

[Analysis of health care needs and evaluation five years after severe brain injuries].

Five years after severe head injury with persistent and extensive deficits of brain functions and loss of working capacity, an assessment and analysis of demand was performed with 31 patients and their relatives. The main impairments consist in the severe changes of personality and in cognitive deficits; they contrast with the spare physical handicaps. A main demand of the relatives are local family groups which are still lacking in many parts of the country.

Activities of Daily Living

Adjusted hypervolemic hemodilution in acute ischemic stroke.

We prospectively randomized 47 patients with acute ischemic stroke of the middle cerebral artery of less than 24 hours' duration to either adjusted hypervolemic hemodilution or control treatment and followed them up for 90 days. Rapid hemodilution to a target hematocrit of 30-35% as monitored with bedside determinations was achieved by using infusions of dextran 40, venesections, and infusions of additional crystalloid solution when necessary. There was no difference in the death rate between the two treatment groups. Of these 47 patients, 37 (19 in the hemodilution group and 18 in the control group) could be followed up for the entire study period of 3 months. The relative improvement in neurologic function from day 1 to days 8, 21, and 90 was significantly better in the hemodilution group than in the control group. In accordance, special tests for fine motor control of the paretic arm disclosed better performance in the hemodilution group. The frequency of patients with severe disability was significantly lower in the hemodilution group on days 8 and 21. Plasma viscosity (measured in 11 patients) was not affected by infusions of dextran 40. Vigorous hypervolemic hemodilution in patients with acute ischemic stroke is well tolerated and improves early neurologic outcome with an effect lasting at least 3 months.

Aged

[Rehabilitation of polytraumatized brain-injured patients].

After head injury, motor deficits (paralysis, spasticity, ataxia) dominate together with cognitive and personality disturbances. Optimal positioning and physiotherapy is important in early treatment to prevent complications later, due to spasticity. Memory and learning deficits can be compensated for with alternate cognitive strategies. Restoration of function after severe cognitive deficits takes a minimum of one year. Personality changes are disruptive to the rehabilitation process and to family reintegration. Therefore an intensive support system for the family is needed.

Brain Damage, Chronic

[Sedation].

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Aged

'Fusimotor set': new evidence for alpha-independent control of gamma-motoneurones during movement in the awake cat.

The discharge activity of single muscle spindle receptors was recorded in freely moving cats. Large changes in responsiveness to length variations was observed in different types of movement. In separate stimulations on anaesthetised cats, the activity of the gamma-fusimotor neurones responsible for these changes was reconstructed. The results suggested that fusimotor action on a given spindle afferent during the movements studied was not rigidly alpha-linked, but 'set' by the CNS to steady levels, and that it could switch from largely static (gamma s) to largely dynamic (gamma d) according to the motor tasks performed.

Animals

On the central generation of locomotion in the low spinal cat.

A central network of neurones in the spinal cord has been shown to produce a rhythmic motor output similar to locomotion after suppression of all afferent inflow. The experiments were performed mainly in acute spinal cats (th. 12), which had received DOPA i.v. and the monoamine oxidase inhibitor Nialamide. In some preparations all dorsal roots supplying the spinal cord were transected, in others phasic afferent activity was suppressed by curarization. The activity was recorded as neurograms from nerve filaments or as electromyograms. It is concluded that: 1. alternating activity between flexors and extensors of foot, ankel, knee, and hip of one limb can still occur 2. the duration of the flexor discharges vary less with the cycle duration than the extensor discharges 3. different flexor muscles may retain individual patterns 4. the activity at different joints can be dissociated 5. there is at least one network for each limb. 6. the coordination between the two hindlimbs can be alternating as in walking or be more closely spaced as in galloping 7. alternating activity in the ankle remains even when only segments L6, L7 and S1 are intact.

Afferent Pathways

Effect of repetitive activation on the afterhyperpolarization in dorsal spinocerebellar tract neurones.

1. The changes in the afterhyperpolarization (a.h.p.) with repetitive activation have been studied in dorsal spinocerebellar tract cells of the cat using intracellular recording techniques. 2. The a.h.p. following a single spike was conditioned at different interspike intervals by a single preceding spike. In the majority of neurones the a.h.p. following a spike added approximately linearly with that generated by a preceding spike. 3. In other cells the a.h.p. following a spike was instead depressed by a preceding spike. THis depression was approximately constant at interspike intervals less than the a.h.p. duration (50-100 msec). Thereafter the a.h.p. slowly recovered during the next 100-300 msec. There was no associated decrease in the initial brief hyperpolarizing undershoot. 4. With shortlasting repetitive activation at high frequency (greater than 100 impulses/sec) the a.h.p, peak amplitude increased progressively with successive spikes (5-15 spikes). No change in the time constant of decay was observed. A good correspondence was found between the observed increase in peak amplitude of the a.h.p.s and that given by a theoretical linear superposition of the successive a.h.p.s. 5. Changes in the brief hyperpolarizing undershoot with repetitive activation is also described.

Action Potentials

Firing behaviour of dorsal spinocerebellar tract neurones.

1. The repetitive discharge evoked by constant current injection from an intracellular micropipette has been studied in dorsal spinocerebellar tract cells of the cat. 2. The discharge frequency decreased with time, the decrease being more pronounced at high current intensities. Most of the frequency change occurred during the first ten intervals but the decrease continued slowly for several seconds. In some cells the frequency rose initially, the first interspike interval being larger than immediately succeeding ones. 3. The frequency-current (f/I) curves for the first interspike intervals were S-shaped, as found in spinal motoneurones. With successive intervals the lower leg of the f/I curve extended to higher frequencies, giving a progressive linearization of the f/I curves. In almost all cells this linearization was completed at 200 msec after current onset. 4. The experimental f/I curves were compared with the f/I curves obtained with a simple neurone model based on the properties of the postspike afterhyperpolarization. For the first interspike interval there was a good agreement between the experimental and calculated f/I curves of individual neurones up to frequencies of several hundred impulses per second. In the high frequency range, it was necessary to compensate for changes in initial postspike voltage trajectories caused by the injected current. Other aspects of the firing of real neurones, such as the progressive linearization of the f/I curves, the negative adaptation and the changes in the interspike voltage trajectories with increasing current were also reproduced by the neurone model. 5. It is concluded that the conductance process underlying the postspike afterhyperpolarization is a major factor in the regulation of repetitive firing in dorsal spinocerebellar tract neurones.

Action Potentials

Central generation of locomotion in the spinal dogfish.

After a transection of the spinal cord a dogfish performs continuous swimming movements with a phase lag between adjacent segments. It is shown that the intersegmental coordination remains after an extensive dorsal root transection as well as after curarization. In the former case the motor activity was recorded electromyographically in several segments along the body, in the latter case the intersegmental coordination was evaluated by recording the efferent activity in different ventral roots along the body. It was concluded that a spinal central network can account for the phase lag observed between successive segments during swimming. It was also shown that the efferent activity from parts of the spinal cord with no dorsal roots intact could be influenced by peripheral stimuli such as pressure on the pelvic fins; this result suggests that some afferent fibres reach the spinal cord via the ventral roots.

Animals

Muscle spindle control during locomotor movements generated by the deafferented spinal cord.

In acute spinalized (Th 12) cats, treated with DOPA, curarized or with all lumbosacral dorsal roots transected, stepping patterns were elicited in the hindlimbs by continuous electrical stimulation of the dorsal roots. Single primary endings in dorsal root filaments or single gamma and alpha efferents in muscle nerve filaments from flexors and extensors were recorded together with the efferent nerve activity to various hindlimb muscles. The experiments showed a clear coactivation of the intra- and extrafusal system to the same muscle. The alpha efferent discharges typically started with a very short first interspike interval. It is concluded that there exists a central spinal alpha-gamma-linkage for locomotion in the hindlimbs.

Animals