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Biomedical subjects

G Roth

Publications and source records attributed to G Roth.

At least 73 records · Page 4Linked to original sources
PubMed1985

Principles of self-generation and self-maintenance.

Living systems are characterized as self-generating and self-maintaining systems. This type of characterization allows integration of a wide variety of detailed knowledge in biology. The paper clarifies general notions such as processes, systems, and interactions. Basic properties of self-generating systems, i.e. systems which produce their own parts and hence themselves, are discussed and exemplified. This makes possible a clear distinction between living beings and ordinary machines. Stronger conditions are summarized under the concept of self-maintenance as an almost unique character of living systems. Finally, we discuss the far-reaching consequences that the principles of self-generation and self-maintenance have for the organization, structure, function, and evolution of single- and multi-cellular organisms.

Animals↗
PubMed1985

Trends in the functional morphology and sensorimotor control of feeding behavior in salamanders: an example of the role of internal dynamics in evolution.

Organisms are self-producing and self-maintaining, or "autopoietic" systems. Therefore, the course of evolution and adaptation of an organism is strongly determined by its own internal properties, whatever role "external" selection may play. The internal properties may either act as constraints that preclude certain changes or they open new pathways: the organism canalizes its own evolution. As an example the evolution of feeding mechanisms in salamanders, especially in the lungless salamanders of the family Plethodontidae, is discussed. In this family a large variety of different feeding mechanisms is found. The authors reconstruct this evolutionary process as a series of "bifurcation points" of either constraints or opportunities forming a sequence of preconditions for the formation of a high-speed projectile tongue characteristic of tropical salamanders. Furthermore, it is shown how parallel evolution of seemingly unrelated domains within an organism such as respiratory physiology, life history biology and pattern of ontogeny has rather direct relevance to the feeding biology, thus demonstrating that organisms always evolve as wholes.

Animals↗
PubMed1985

[Muscle-nerve ephapse in chronic denervation? Axonal localization].

Muscle-to-nerve ephaptic responses, taking place between a reinnervated motor unit and a motor axon, have been reported in the case of chronic denervation (Roth and Magistris, 1985). One of these responses is described here. Its main features are that it manifests itself as a motor unit potential, which, when present, is evoked either as a direct tardive response (RE), or as an indirect F response, the two potentials never being observed together on any recording. The characteristics of these potentials show that two distinct competitive pathways lead to the same muscular fiber group which suggests the existence of an ephaptic connection. Furthermore, a slight difference in the shape of the RE and F potentials suggests an axon terminal branch localisation of this ephapse.

Carpal Tunnel Syndrome↗
PubMed1985

Long-lasting conduction block in hereditary neuropathy with liability to pressure palsies.

We detected 29 conduction blocks in 12 patients with hereditary neuropathy and liability to pressure palsies. The blocks occurred at entrapment sites, most often the ulnar nerve at the elbow. Some had lasted for several years. This kind of block seems to be characteristic of the neuropathy, and may be related to the localized thickening of myelin ("tomacula"). In one patient with two permanent and severe blocks, neurolysis was beneficial.

Humans↗
PubMed1985

[Hysterography with afterloading-applicator in place. A simple method for improving the treatment planning of uterine cancer].

Anatomical configurations often are an obstacle to a convenient dose-distribution in intracavitary afterloading irradiation. Multiple applicators (splay applicators, twin applicators) cannot be introduced in all cases because of the necessary cervix dilatation. In several cases can be demonstrated, that a defined intracavitary irradiation is possible only by hysterographic control of the intrauterine position of the applicator. By this control generally a mono-applicator is sufficient, which can be placed according the anatomy of the uterine cavity in each session. For this purpose a simple hysterographic method with applicator in position is demonstrated, which requires only few additional effort during intracavitary irradiation.

Aged↗
PubMed1984

Distribution of accessory and hypoglossal nerves in the hindbrain and spinal cord of lungless salamanders, family Plethodontidae.

Study of the innervation of the musculature related to feeding behavior in plethodontid salamanders by means of the horseradish peroxidase (HRP) technique has demonstrated the existence of a true spinal accessory nerve which innervates neck musculature, enters the brain via the ganglion of IX/X cranial nerves and has its motor neurons within the nucleus of the second spinal nerve. Further, it has been shown that the first spinal nerve, being strictly motor, alone constitutes the ramus hypoglossus and is, therefore, homologous to the hypoglossus of amniotes.

Animals↗
PubMed1984

Motor axon loop: an electroneurographic response.

A new kind of response to the stimulation of the median and ulnar nerves was observed in 10 patients. It is a motor unit showing a late latency in response to a weak stimulus and then suddenly a normal latency when the intensity is increased to a critical level. These two responses can be evoked at any level of a distinct nerve segment, the difference between their latencies being constant. The late response cannot be elicited below this segment and the normal response cannot be elicited above this segment. Its F-latency is delayed and does not vary when the late response changes in a normal one. The conduction velocity along the axon seems normal. We propose the hypothesis of a motor axon loop along the nerve, with the recurrent portion traveling in the " grandes ellipses" or the classical anastomosis. These kinked axons are probably congenital; their frequency is still unknown.

Adult↗
PubMed1984

Fasciculations and their F-response. Localisation of their axonal origin.

A fasciculation with an axonal origin may be followed by its own F-response. The time-lapse between these 2 potentials corresponds to the time for the antidromic wave to travel to the alpha-cell and to return to the trigger-point. This relatively stable interval may be compared with the difference between the latencies of the F- and M-responses of the same muscle evoked by distal nerve stimulation. This permits one to localise the origin of the fasciculation on the axon. This method showed that, of 201 fasciculations followed by their F-response, obtained in normal controls and in neurological patients, 97 and 89% respectively had their origin between the muscle and the stimulation site. In this series, the proportion of pathological fasciculations having an origin between the muscle and a point at half the M-latency, is similar to that found in a former study on unselected fasciculations using a collision method (Roth 1982). Comparison between these 2 studies therefore supports the concept that all or almost all fasciculations have an axonal origin.

Axons↗
PubMed1984

Normal survival of Rh0 (D) negative, LW (a+) red cells in a patient with allo-anti LWa.

The serum of an Rh0 (D)+ Caucasian female with a prior history of transfusions contained anti- LWa , reacting moderately with Rh0 (D)+ and weakly with Rh0 (D)- red cells at the antiglobulin phase. Since transfusions were required, Chromium (51Cr) survival studies and mononuclear phagocyte assays (MPA) were used to predict in vivo survival. The MPA value of 6% of the positive control predicted a low likelihood of clinically significant extravascular destruction and 51Cr survival studies indicated greater than 95% survival at 1 h and 78% survival at 20 h for rr erythrocytes. Transfusion of 4 units of Rh0 (D)-, serologically incompatible red cells increased the hemoglobin from 5.2 to 11.4 g/dl and the titer of anti- LWa against rr red cells from 4 to 1,024 7 days after the transfusion. A second 51Cr survival also indicated normal survival of rr erythrocytes. 3 additional Rh0 (D)- units were successfully transfused.

Aged↗
PubMed1984

[Hereditary fragility of the peripheral nerves. Clinical and neurophysiologic study of 23 cases. Review of the literature].

The literature concerning hereditary neuropathy with liability to pressure palsies is reviewed. We describe 23 affected members of 7 families; one of them studied since 1966. The differential diagnosis with heredofamilial plexus brachialis neuropathy and Charcot-Marie-Tooth syndrome is discussed. Our subjects are similar to those described in the literature; they have presented episodes of recurring painless palsies, most often related to minimal neural trauma. Neuromyographic examinations revealed chronic denervation, slowed conduction velocities particularly at entrapment sites and sometimes neurapraxia. We emphasise the conduction blocks for we believe their tendency to long duration (up to 8 years) and presence at several sites in a same patient are characteristic of this affection. Moreover we suggest that this neurapraxia is related to the existence of the tomacula. The possibilities of prevention and treatment are reviewed (two neurolyses performed in one patient presenting with long lasting conduction blocks at 2 entrapment sites have proved to be a successful treatment.

Adolescent↗
PubMed1983

Tongue evolution in lungless salamanders, family plethodontidae. III. Patterns of peripheral innervation.

Innervation of the tongue and associated musculature in plethodontid salamanders was studied using Palmgren stained sectioned materials, fresh dissection, and whole mounts of experimental specimens treated with horseradish peroxidase (HRP). Species studied were chosen to represent modes of tongue projection recognized by Lombard and Wake ('77). Special attention was given to species of the genera Plethodon, Batrachoseps, Pseudoeurycea, and Hydromantes, but representatives of other genera were investigated. As expected we found that cranial nerves IX and X and spinal nerve 1 supplied the muscles involved in tongue movement. The peripheral courses of the nerves were traced, and both functionally related and phylogenetically determined routes were found. As relative projection length increases, the nerves supplying the tongue tip also increase in length. When the tongue is at rest the long nerves are stored in coils. The coil of ramus lingualis lies between the ceratobranchials, but that of ramus hypoglossus is more variable, although constant within a species. Ramus hypoglossus bifurcates into separate branches to tongue and anterior musculature of the floor of the mouth. In generalized, presumably primitive, modes the bifurcation and coiling are far anterior. In most of the tongue projection modes bifurcation is relatively posterior, but in one, bifurcation is anterior, but coiling is relatively posterior in position. The most unusual condition is in Hydromantes, in which bifurcation is relatively posterior and a coiled ramus hypoglossus joins a coiled ramus lingualis to form a unique, coiled common ramus to the tongue tip. Hydromantes has the greatest projection distance of any salamander.

Anatomy, Comparative↗
PubMed1983

[Reinnervation in obstetrical brachial plexus paralysis].

Post-paralytic associated movements ("co-contractions") in 16 cases with obstetrical brachial plexus palsy (OPP) were studied by a neurographic method. This consisted of stimulating a nerve and searching for heterogeneous motor axon reflexes (HAR) in the muscles of the upper limb and shoulder. HAR can be elicited when branches of a single axon reach two different muscles, even very distant from each other. The anatomy of the plexus and the fact that regenerating axons maintain direction determine the frequency with which two muscles are connected. Most HAR are recorded in muscles innervated by the same nerve or roots. More than 800 of them were recorded, mainly in muscles with associated movements. Motor fibers were also detected in sensory nerves. The synkinesis can be explained by a complexe misdirection ("fausse route complexe"): the branches of a single axon reach several muscles. There is no need to propose a simple misdirection ("fausse route"), implying that an axon simply changes direction to innervate another muscle, nor to call upon modifications of the central motor patterns. The proposed mechanisms of associated movements in the OPP explains the impossibility of suppressing them by reeducation.

Adolescent↗
PubMed1982

Afferent visual projections in three species of lungless salamanders (family Plethodontidae).

Afferent visual projections were demonstrated in three species of plethodontid salamanders by means of anterograde transport of horseradish peroxidase. On the contralateral side three optic tracts and seven neuropil areas can easily be distinguished, which are similar among the three species examined as well as in European salamandrids. On the ipsilateral side the marginal optic tract shows great diversity. The retinal projections of the latter range from weakly labeled terminal fields restricted to the thalamus to heavily labeled fields covering the entire tectum opticum.

Animals↗
PubMed1982

The origin of fasciculations.

A collision method in a single axon was used to determine the origin of 100 fasciculations in various lower motor neuron lesions. For 80% of the fasciculations, it was situated on the distal extremity of the axon regardless of the type of lesion, its duration, or the severity of the denervation. For several reasons, this proportion is underestimated. The fasciculations of distal origin were sometimes, associated with double discharges, the mechanism of production and clinical significance of which probably differ.

Axons↗
PubMed1982

Responses in the optic tectum of the salamander Hydromantes italicus to moving prey stimuli.

In the tectum opticum of Hydromantes italicus neurons were recorded extracellularly which responded selectively to moving visual stimuli. Part of the recorded cells were marked iontophoretically by means of alcian-blue dye for anatomical localization. Out of a total of 110 neurons six groups could be distinguished which preferred the square stimulus but differed strongly in their responses to rectangles oriented either vertically or horizontally. Two of these groups showed stimulus preference inversion if the stimulus velocity was changed. These response patterns displayed characteristic differences with those known in other amphibia, well corresponding to differences in the prey catching behaviors.

Animals↗
PubMed1982

Response characteristics and stratification of tectal neurons in the toad Bufo bufo (L.).

In the optic tectum of Bufo bufo the activity of single neurons was recorded during the presentation of moving visual stimuli. The location of the recorded cells was marked iontophoretically by means of alcian blue dye. A total of 132 cells were studied, most of which showed clear differences within their responses to a square and to rectangles oriented either horizontally or vertically. The cells were found primarily within the tectum layers 8 and 6. The majority of them preferred the square to the horizontal bar, and this stimulus to the vertical one. Another group responded best to the horizontal rectangle. Relatively few cells were found in which the vertical stimulus was preferred to the horizontal one. A considerable number of tectal cells showed a change of stimulus preference if the stimulus velocity was changed. No clear correlation between response types and anatomical distribution within the tectum layers could be found.

Animals↗