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G Roth

Publications and source records attributed to G Roth.

At least 37 records · Page 2Linked to original sources
PubMed1988

Topography and cytoarchitecture of the motor nuclei in the brainstem of salamanders.

The organization of the motor nuclei of cranial nerves V (including mesencephalic nucleus), VI, VII, IX, and X is described from HRP-stained material (whole mounts and sections) for 25 species representing five families of salamanders, and the general topology of the brainstem is considered. Location and organization of the motor nuclei, cytoarchitecture of each nucleus, and target organs for nuclei and subnuclei are described. The trigeminal nucleus is separated distinctly from the facial and abducens nuclei and consists of two subnuclei. The abducens nucleus consists of two distinct subnuclei, one medial in location, the abducens proper, and the other lateral, the abducens accessorius. The facial nucleus has two subnuclei, and in all but one species it is posterior to the genu facialis. The facial nucleus completely overlaps the glossopharyngeal nucleus and partially overlaps that of the vagus. In bolitoglossine plethodontid salamanders, all of which have highly specialized projectile tongues, the glossopharyngeal and vagus nuclei have moved rostrally to overlap extensively and intermingle with the anterior and posterior subnuclei of the facial nerve. In the bolitoglossines there is less organization of the cells of the brainstem nuclei: dendritic trunks are less parallel and projection fields are wider than in other salamanders. Some aspects of function and development are discussed; comparisons are made to conditions in anurans; and phylogenetic implications are considered.

Abducens Nerve↗
PubMed1988

Organization of the motor nuclei in the cervical spinal cord of salamanders.

The distribution and cytoarchitecture of motor nuclei of the cervical spinal cord were studied by using HRP techniques (whole mounts and sections) in 22 species of salamanders (families Hynobiidae, Dicamptodontidae, Ambystomatidae, Salamandridae, and Plethodontidae) representing a wide variety of life histories and functional modes of feeding. The nucleus of the first spinal nerve extends from the level of, or slightly caudad to, the root of the tenth cranial nerve, almost to the ventral root of the second spinal nerve. Approximately one-half of this nucleus is situated in the brainstem. This anterior extension is longest in bolitoglossine plethodontids. The nucleus of the second spinal nerve extends from the root of the first spinal nerve to the dorsal root of the second spinal nerve. The nuclei of the first and second spinal nerves in all species except bolitoglossines have motor neurons arranged in two columns: a lateral one containing large spindle-shaped cells and a medial one containing pear-shaped or polygonal smaller cells. The primary dendrites of these lateral and medial cells are parallel and their arborization is relatively narrow. In contrast, bolitoglossines lack the lateral motor column. The nucleus of the first spinal nerve consists only of a medial band of pear-shaped and sometimes polygonal cells, and the nucleus of the second spinal nerve is a wider band of pear-shaped and polygonal cells which are always situated inside the periventricular gray matter. The arrangement of the somata in bolitoglossines is less organized and the primary dendrites are less parallel and have a broader arborization than in other salamanders. In all species, cells in the second spinal nucleus are arranged in a less orderly manner than those in the first. All salamanders studied possess a spinal accessory nerve whose motor neurons are located in the cervical spinal cord; the axons leave the brainstem with fibers of the vagus nerve. The rostrocaudal extent of this nucleus differs markedly among species. In bolitoglossines the nucleus is more or less restricted to the region of the nucleus of the second spinal nerve. In all other species studied, the accessory nucleus extends from the obex to the caudal end of the nucleus of the third spinal nerve. In the tribe Plethodontini the cytoarchitecture of the accessory nucleus is similar to that of the second spinal. In desmognathine and hemidactyliine plethodontids as well as in all nonplethodontid species studied the nucleus consists of pear-shaped and cone-shaped cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Accessory Nerve↗
PubMed1988

Miniaturization, genome size and the origin of functional constraints in the visual system of salamanders.

During their evolution, many species of lungless salamanders (fam. Plethodontidae) have experienced a great increase in genome size and consequently in the size of their cells, including sensory receptors and neurons. In addition, some have become extremely miniaturized. The consequences of these events and the morphological compensatory processes are studied in the visual system of juvenile and adult salamanders.

Animals↗
PubMed1988

Observer variation in the diagnosis of dysplasia in Barrett's esophagus.

The potential value of biopsy surveillance of patients with Barrett's esophagus for dysplasia is diminished by a lack of agreement on the diagnostic criteria for dysplasia. In a preliminary consensus conference, experienced gastrointestinal pathologists from four medical centers agreed on criteria for a five-tiered histologic classification of dysplasia in Barrett's esophagus--negative for dysplasia, indefinite for dysplasia, low-grade dysplasia, high-grade dysplasia, and intramucosal carcinoma. Eight morphologists in the four centers tested the criteria for interobserver agreement by examining a set of coded slides that had been chosen to include some especially difficult interpretative problems in all five histologic classifications. Interobserver agreement of 85 and 87% was achieved in successive reviews when the combined group of high-grade dysplasia and intramucosal carcinoma was compared with the combined group of low-grade dysplasia, indefinite for dysplasia, and negative for dysplasia. Comparison of other groups yielded less agreement. For example, negative for dysplasia could be distinguished from all other diagnoses with an interobserver agreement of 72%. We conclude that experienced gastrointestinal morphologists can diagnose high-grade dysplasia and intramucosal carcinoma with a high degree of agreement and thus can detect those patients who may need immediate rebiopsy or esophageal resection. Either further refinement of histologic criteria or alternate diagnostic methods will be needed to achieve the reproducible diagnosis of indefinite changes and low-grade dysplasia. This is important because patients with such changes theoretically merit closer endoscopic surveillance.

Barrett Esophagus↗
PubMed1988

[Post-radiation brachial plexopathy. Persistent conduction block. Myokymic discharges and cramps].

The distinction between radiation and tumor brachial plexopathy may be difficult. The electrophysiological recording of myokymic discharges, frequently present in the former but rare in the latter type of plexopathy, can be helpful for the diagnosis. However, the pathophysiology and the site of origin of these discharges remain unclear. We describe a patient presenting with radiation brachial plexopathy, clinical myokymia, cramps and pain. In this patient, the myokymia--due to abundant myokymic discharges--and the cramps, were related to the existence of persistent conduction block of several years duration. Several findings suggest that the myokymic discharges were generated on blocked axons: voluntary activity did not influence their occurrence nor modify their course; the motor unit potentials involved in the discharges were not evoked by stimulation proximal to the site of the conduction block, whereas the stimulation distal to this site could evoke, modify the rhythm, or interrupt the course of the discharges; the latency of these evoked responses indicated that the site of reflection was proximal on the axon, and likely coincided with that of the conduction block. Recent observations (Roth and Magistris, 1987b) indicated that myokymia, produced by numerous single or grouped fasciculations generated on axon terminals, may be related to persistent conduction blocks of various etiologies. The present case demonstrates that myokymia provoked by myokymic discharges may as well be related to persistent conduction block. The reason why these blocks are accompanied by fasciculations in some situations and by myokymic discharges in others remains an unsolved question. The cramps observed in this patient were also of interest as they occurred in the muscle territory of blocked axons and were provoked by passive muscle shortening. Their origin, distal to the conduction block, is unknown. Finally, a neurolysis did not prevent the progressive transformation of conduction block into axonotmesis.

Brachial Plexus↗
PubMed1987

Mathematical model and simulation of retina and tectum opticum of lower vertebrates.

The processing of information within the retino-tectal visual system of amphibians is decomposed into five major operational stages, three of them taking place in the retina and two in the optic tectum. The stages in the retina involve (i) a spatially local high-pass filtering in connection to the perception of moving objects, (ii) separation of the receptor activity into ON- and OFF-channels regarding the distinction of objects on both light and dark backgrounds, (iii) spatial integration via near excitation and far-reaching inhibition. Variation of the spatial range of excitation and inhibition allows to account for typical activities observed in a variety of classes of retina ganglion cells. Mathematical description of the operations in the tectum opticum include (i) spatial summation of retinal output (mainly of class-2 and class-3 retina ganglion cells), and (ii) direct or indirect lateral inhibition between tectal cells. In the computer simulation, first the output of the mathematical retina model is computed which, then, is used as the input to the tectum model. The full spatio-temporal dynamics is taken into account. The simulations show that different combinations of strength of lateral inhibition on the one side and the response properties of the retina ganglion cells on the other side determine the response properties of tectal cell types involved in object recognition.

Amphibians↗
PubMed1987

Neuropathies with prolonged conduction block, single and grouped fasciculations, localized limb myokymia.

Fourteen patients presented prolonged conduction block (CB) related to hereditary neuropathy with liability to pressure palsies (n = 7), neuropathy with proximal multifocal persistent CB (n = 2), radiation plexopathy (n = 3) and chronic acquired polyneuropathy (n = 2). All subjects presented both single and grouped fasciculation potentials that resulted in visible limb myokymia in 9 patients. This ectopic activity was recorded only in muscles affected by the CB, was more important in severe or complete CB, and often arose from terminal branches of blocked axons. These fasciculations and grouped fasciculations therefore appear to be causally related to the CB. In the presence of localized myokymia, a prolonged CB should be suspected.

Chronic Disease↗
PubMed1987

Nuclear magnetic resonance imaging of a patient with an ectopic pregnancy.

We attempted to demonstrate the morphological changes of an extrauterine pregnancy by nuclear magnetic resonance imaging. Spin echo mode was used to take images in all three space directions. An enlargement of the uterus with an empty cavity and a hyperplasia of the supporting vasculature were demonstrated as alterations correlating with an extrauterine pregnancy.

Adult↗
PubMed1987

Differential effects of hydrocortisone, fluocortolone, and aldosterone on nocturnal sleep in humans.

Previous experiments have suggested that sleep processes are sensitive to influences of corticosteroids. The present experiment was designed to compare effects of three different corticosteroids on human sleep: fluocortolone (a synthetic pure glucocorticoid), cortisol which possesses glucocorticoid and mineralocorticoid activity, and aldosterone (the major mineralocorticoid). Ten male adult subjects were tested in four experimental nights according to a double-blind latin-square design under conditions of either 1.0 mg of aldosterone, 20 mg of fluocortolone, 80 mg of hydrocortisone, or placebo. Substances were administered orally (fluocortolone, 23.00 h) or infused iv throughout the night (hydrocortisone, aldosterone) starting at 23.00 h. Hydrocortisone and fluocortolone induced a substantial reduction of rapid eye movement sleep. Hydrocortisone increased slow wave sleep activity. No such effect was observed after fluocortolone. Effects on sleep processes of aldosterone, in general, seemed to be neglegible. The results demonstrate differential effects of synthetic glucocorticoid, cortisol, and aldosterone on sleep in humans, which may be attributed to the heterogeneity of corticosteroid receptors in the brain.

Administration, Oral↗
PubMed1986

[Nuclear magnetic resonance imaging of uterine cancer with and without the administration of the paramagnetic contrast medium Gd-DTPA].

Patients with a corpus carcinoma were examined by magnetic resonance imaging before and after application of the paramagnetic contrast agent Gd-DTPA. The images were obtained by spin echo technique with the repetition times 0.5 s or 1.8 s and the echo times 35/70 ms. The dosis of the contrast agent was 0.1 mmol per kg body weight. The contrast between myometrium and tumour increased after injection of the contrast agent and structures within the tumour can be better differentiated. The pelvic organs (bowel and urinary bladder) can be seen in greater detail. Images taken with short repetition times after application of Gd-DTPA show greater contrast than pictures picked up with the same imaging parameters without contrast agent. Furthermore, there is an improvement compared with images taken with long repetition times.

Aged↗
PubMed1986

Motor neuropathy with proximal multifocal persistent conduction block, fasciculations and myokymia. Evolution to tetraplegia.

We describe a patient with chronic asymmetric motor neuropathy, which began in the upper extremity. The paretic muscles showed abundant fasciculations and myokymia but only little amyotrophy. Electrophysiologic examination revealed proximal multifocal persistent conduction block (CB) not located at the usual entrapment sites, and arrhythmic isolated or grouped fasciculation potentials originating distally on blocked axons. Over the years, new CBs developed, which led to tetraplegia, and amyotrophy slowly increased with progressive denervation. This patient differs from the cases of chronic acquired demyelinating polyneuropathy described in the literature by the absence of sensory deficit and the proximal location of CB.

Demyelinating Diseases↗
PubMed1985

The structure of the brainstem and cervical spinal cord in lungless salamanders (family plethodontidae) and its relation to feeding.

We present an HRP study of the sensory tracts and motor nuclei associated with feeding (especially use of the tongue) in plethodontid salamanders (mainly Batrachoseps attenuatus, Bolitoglossa subpalmata, Desmognathus ochrophaeus, Eurycea bislineata, and Plethodon jordani). The nerves studied are VII (ramus hyomandibularis only), IX, X, XI, the first spinal nerve (hypoglossus), and the second spinal nerve. Two types of sensory projections are universally found in the brainstem: superficial somatosensory projections of VII, IX, and X, and deeper visceral sensory projections of IX and X to the fasciculus soltarius. The first spinal nerve and the spinal accessory nerve (XI) have no sensory projections, but the second spinal nerve has typical projections along the dorsal funiculus of the spinal cord. The motor nuclei of VII ramus hyomandibularis, IX, and X form a combined nucleus situated at the level of the IX/X root complex. The nucleus of the first spinal nerve is well separated from the combined nucleus and is situated rostral and caudal to the obex. The rostral part of the motor nucleus of the second spinal modestly overlaps that of the first. The motor nucleus of the spinal accessory nerve is more or less restricted to the region of the second spinal nerve. Its fibers leave the brain through the last root of the IX/X complex and the related ganglion. Bolitoglossine and nonbolitoglossine differ in the architecture of the spinal nuclei. Two distinct types of motor neurons occur in spinal nuclei of nonbolitoglossine species--some of those with tongue projection--but only one type is found among the tongue-projecting bolitoglossine group.

Animals↗
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↗