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Biomedical subjects

M Zimmermann

Publications and source records attributed to M Zimmermann.

At least 379 records · Page 21Linked to original sources
PubMed1978

External nucleus of inferior colliculus: auditory and spinal somatosensory afferents and their interactions.

1. The discharges of 129 units were studied in the external nucleus of the inferior colliculus of 11 anesthetised and paralyzed cats. This region is known to receive fibers from auditory nuclei and the dorsal column nuclei. 2. Stimuli used were pure tone bursts, monaural or binaural, tactile stimulation of the body surface, and electrical stimulation of the dorsal columns (DC) at a low cervical level and of the contralateral and ipsilateral tibial nerves. 3. Forty-six percent of units were only influenced by one type of stimulation (26% auditory, 20% DC). Of the remaining bimodally influenced units, the majority was excited by pure tone stimuli and inhibited by DC stimulation. 4. A small proportion of the total population (18%) was excited by both DC and auditory input, and units sensitive to both tones and tactile stimulation of the skin were rare (4%). 5. Auditory tuning curves were generally very broad compared with those of units in the central nucleus of the inferior colliculus. Similarly, somatic receptive fields were large and usually extended over a whole limb. 6. The majority of tone-responsive units were influenced binaurally (70%); most somatic receptive fields were located on the contralateral fore- or hindlimb (16/18). 7. The results indicate that both auditory and somatosensory information is contained in the discharges of units in the external nucleus of the inferior colliculus. 8. Speculations are made about the role of this nucleus in descending auditory input to the spinal cord and in the comparison of auditory and cutaneous information during sound-evoked coordinated body movements.

Acoustic Stimulation↗
PubMed1978

[Incomplete lead fracture as a cause of bradyarrhythmia in patients with artificial pacemakers (author's transl)].

The fracture of a permanent cardiac pacing lead may be complete or incomplete. In the first case, the function of the pacemaker system will completely cease. An incomplete fracture, however, is defined as a capillary interruption of the wire and will lead to a loose connexion between both parts of the electrode. This, in turn, may result in sudden changes of the electrical resistance of the lead and, therefore, in alterations of the electrode voltage during the second part of the biphasic current wave delivered by the pacemaker; this voltage change--in the 10-mV-range--will inhibit a blocking demand pacemaker with an intermittent, irregular increase of the pacemaker escape interval as the corresponding ECG finding. Usually, this "oversensing" phenomenon can be eliminated by turning the pacemaker function to the fixed rate mode with a test magnet applied. -- Although this malfunction is more often seen with bipolar pacemaker systems and with epicardial wires, it may also occur in a unipolar, transvenous system. -- Among 2100 patients, we have seen this malfunction in 6 cases in whom other, even more rare causes--such as a defect of the electronic circuit of the pulse generator, muscle potentials, etc.--could be ruled out. The x-ray findings revealed no evidence of a lead fracture in any case. The diagnosis was established on the ECG, the examination of the surgically removed electrode in 2 cases, and the finding, that only the implantation of a new lead abolished the malfunction, whereas the implantation of a new pacemaker alone ws ineffective.

Bradycardia↗
PubMed1976

Radio diagnosis using 125I-fibrinogen and 203Hg-thymidine.

A comparative study of 125I-fibrinogen and 203Hg-thymidine using 144 Ehrlich carcinoma-bearing mice, indicates that tumor affinity of carrier substances with covalent labeling could be better used for scintigraphic tumor diagnosis. Halogenated or possibly metallo-organic compounds offer an alternative to the metal complexes in general use up to now.

Animals↗
PubMed1976

[Neurophysiological basis of pain and pain therapy (author's transl)].

Painful stimuli are encoded by specialized nociceptors. In the spinal cord the afferent nerves transmit them at the synapse to dorsal horn neurons, which are considered here as models for neuronal mechanisms in nociception. In particular, inhibitory effects of spinal and of supraspinal origin are shown to modulate the nociceptive messages ascending to the brain. These inhibitions are activated by various methods of electrostimulation (of the peripheral nerves, dorsal columns, electroacupuncture) that are used clinically for the management of pain.

Analgesia↗
PubMed1976

[Distribution study using 57Co-, 51Cr-, 111In- and 99mTc-bleomycin in mice with a solid Ehrlich carcinoma].

From the comparative studies of 57Co-, 51Cr-, 111In- and 99mTc-Bleomycin using 282 solid Ehrlich-carcinoma-bearing mice, 57Co was found to be the most suitable bleomycin preparation for tumorscintigraphy. The results obtained by 111In-Bleomycin of linear tumor cell absorption indicates a possible use of 111In-Bleomycin as an agent for objective histological differentiation also in cells previously treated with therapeutic agents.

Animals↗
PubMed1973

Dorsal root potentials produced by afferent volleys in cutaneous group 3 fibers.

1. Dorsal root potentials (DRP) were recorded in the lumbosacral spinal cord of decerebrated unanaesthetized cats, following afferent volleys restricted to the thin myelinated (Group III) cutaneous afferents of the hind limb. The thick myelinated fibres (Group II) were blocked by a depolarizing current.2. A pure Group III volley produced a DRP of negative polarity, called the III-DRP, signalling a depolarization of the intraspinal terminals of afferent fibres. The longer latency of the III-DRP when compared to that of the DRP after a Group II volley was accounted for quantitatively by the lower conduction velocity of the Group III fibres.3. Special attention was given to the presence of III-DRPs having a predominantly positive polarity thus signalling a presynaptic hyperpolarization. Such ;positive III-DRPs' were, however, never observed in this investigation.4. Both after transection of the spinal cord at various levels and after administration of pentobarbitone the III-DRP persisted at normal polarity. The duration of the DRPs was increased by these experimental procedures.5. The implications of these findings are discussed in relation to the prominent role postulated for the Group III fibres in the context of the gate control theory of pain.

Animals↗