Biomedical subjects
Publications and source records attributed to J Arvidsson.
After application of a solution of horseradish peroxidase (HRP) around intact sciatic nerve axons in the rat, numerous HRP-labeled neurons were found in the ipsilateral L5 dorsal root ganglion and spinal cord ventral horn. These findings indicate that HRP enters intact peripheral nerve axons, and is transported retrogradely from its site of entry to their cell bodies of origin.
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According to a current theory about the pathogenesis of Bell's palsy, the motorfibers of the facial nerve are affected by a viral neuropathy, transmitted to the facial nerve via the axons of the chorda tympani nerve. We have used horseradish peroxidase (HRP) to test to what extent and under what conditions uptake and transport of macromolecules can take place from the tongue. When HRP was applied directly onto the mucosa, no labeling was observed. However, when applied to localized superficial lesions of the epithelium or injected into the tongue, HRP is transported retrogradely to the geniculate and trigeminal ganglia, superior salivatory and hypoglossal nuclei. Injection of HRP resulted in many more labelled cells as well as fiber labeling in the peripheral nerves, in the solitary and spinal trigeminal nuclei. The findings show that even after a minor-superficial lesion in the tongue, exogenous macromolecules are taken up and transported to the intratemporal portion of the facial nerve as well as other cranial nerves. These findings are compatible with the theory that Bell's palsy is a neuropathy caused by neurotropic viruses spread via the chorda tympani.
Transganglionic transport of horseradish peroxidase (HRP) has been used to study the cell bodies and central projections of neurons innervating the vibrissae in the rat. These can be grouped into five horizontal rows and one posterior vertical row. Twenty-four to 48 hours after the nerves innervating different vibrissae were exposed to HRP, the trigeminal ganglia, brainstem, and upper cervical spinal cord were fixed by perfusion and serial sections were processed according to the tetramethylbenzidine technique. The results revealed a tendency for somatotopic organization in the trigeminal ganglion of cell bodies innervating the different vibrissae. Corresponding termination areas in the trigeminal sensory nuclei showed a detailed pattern of organization replicating the peripheral organization of the vibrissae. In all trigeminal sensory nuclei the horizontal rows are represented in an inverted fashion from dorsal to ventral, i.e., the most dorsal row is represented most ventrally. In addition, the more anterior a vibrissa is located, the deeper is it represented in the rostral nonlaminated nuclei. The situation is reversed in the laminated nucleus caudalis. The posterior vertical row is represented most superficially in the rostral nonlaminated nuclei, but most deeply in the laminated nucleus caudalis. In nucleus caudalis there are also rostrocaudal differences in the representation of different vibrissae. Thus, the posterior vibrissae in a horizontal row have their main representations more caudally than the anterior vibrissae. The posterior vertical row has its main representation most caudally, in the C1 segment.
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Trigeminal ganglia and brain stem of adult cats were studied following HRP injections into tooth pulps or after exposure of the cut end of the inferior alveolar nerve to HRP. Ipsilateral ganglion cells within a wide range of sizes were labeled in both experimental situations, whereas no labeled cells were observed in the contralateral ganglion in any animal. Labeled central branches of tooth pulp and inferior alveolar neurons were observed in all subdivisions of the ipsilateral trigeminal sensory complex. Terminal labeling in the tooth pulp experiments was confined to the dorsomedial parts of the main sensory nucleus and subnuclei oralis and interpolaris. Caudal to the obex terminal labeling was restricted to the medial halves of laminae I, IIa and V of the medullary dorsal horn. In the inferior alveolar nerve experiments dense terminal labeling was observed in the dorsal parts of the main sensory nucleus and subnuclei oralis and interpolaris. Caudal to the obex terminal labeling was located throughout laminae I to V in contrast to the tooth pulp experiments. Neither of the two experimental situations offers any evidence for a bilateral or contralateral brain stem projection of primary trigeminal neurons.
ACTH in high doses and over long periods of time is the treatment of choice in infantile spasm. Serious side effects can occur, but are not so often described. Two cases are published with hypertonia and immunosuppression. Control of blood pressure and electrolytes is mandatory. The importance of rather careful control of infections is stressed, as symptoms during ACTH-therapy are somewhat altered.
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Transganglionic degeneration has been studied with the Fink-Heimer method in the trigeminal sensory nuclei of adult cats and rats following peripheral nerve transections. Degeneration was observed ipsilaterally as well as contralaterally in all cats, surviving 11-30 days after transection of the infraorbital nerve. In the rats the infraorbital or the auriculotemporal nerve was transected. After transection of the former nerve the first signs of transganglionic degeneration were observed after 7 days postoperative survival and even after 130 days there were still a lot of degenerating structures present. Between 7 and 14 days survival there was a small amount of degeneration in substantia gelatinosa. After transection of the auriculotemporal nerve, degeneration was observed only in the most caudal parts of the trigeminal sensory nuclear complex. Opposite to the situation in the cat, there was no contralateral degeneration in the rat. All degeneration areas were somatotopically organized, both in the cat and in the rat. The results are discussed in relation to a previous study of transganglionic degeneration in the trigeminal sensory nuclear complex by the authors and to anatomical and physiological studies of somatotopic organization in the trigeminal sensory nuclei. They clearly show the value of transganglionic degeneration used as a tool for analysis of central projections of primary sensory neurons.
In adult rats subjected to unilateral transection of the infraorbital nerve, the main sensory trigeminal nucleus was studied by electron microscopy. Post-operative survival times varied between 2 and 60 days. A variety of ultrastructural alterations was observed from the sixth post-operative day onwards. These changes were in many respects similar to those seen in the course of Wallerian degeneration. Neurofilamentous boutons and axons were found 6-30 days post-operatively. Various types of dark boutons were observed between 7 and 30 days and axonal changes indicative of degeneration between 7 and 60 days post-operatively. Astrocytes and microglial cells contained degenerating structures 7-60 days post-operatively. The alterations observed in the present study are interpreted as related, at least in part, to the nerve cell degeneration and the nerve cell death previously shown to occur in the trigeminal ganglion after infraorbital nerve transection.
The cut end of the sciatic nerve of adult rats was exposed to horseradish peroxidase (HRP). The rats were allowed to survive for 12 h--5 days. 12--18 h postoperatively small dorsal root ganglion cells more heavily labeled than large ones. After 48--72 h more large cells were intensely labeled. From 18 h onwards large amounts of HRP labeling was observed ipsilaterally in the superficial laminae of the dorsal horn, from 48 h also in deeper laminae and in the gracile nucleus. The heavy labeling clearly indicates the potential of the present approach for mapping purposes. The findings also indicate that short postoperative survivals can be used for rather selective marking of small cells and fibers.
Trigeminal ganglia of normal rats and of adult rats subjected to unilateral transection of the infraorbital nerve were studied by light and electron microscopy. Counts of ganglion cells in ganglia on operated and unoperated sides were made following long postoperative survival times. The ultrastructural changes in ganglia of the operated side were studied from 3 to 70 days postoperatively. The quantitative observations show that a considerable loss of ganglion cells takes place on the operated side. The ultrastructural observations demonstrate the occurrence of ganglion cell degeneration, nerve fibre degeneration and phagocytosis by satellite and Schwann cells. The results are compatible with the view that degeneration of trigeminal afferents in the brain stem following lesions of peripheral trigeminal nerve branches is related to retrograde degeneration of trigeminal ganglion cells.
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In 16 kittens either the frontal or the inferior alveolar nerve was transected and in 17 adult rats either the supraorbital, the infraorbital or the mental nerve was divided. The postoperative survival periods were kept at 3-28 days for the kittens and 15-26 days for the rats. Sections from the caudal brain stem and the upper part of the cervical cord were impregnated according to the Fink-Heimer method, procedure II. In the kittens degeneration was found after the 8th postoperative day ipsilaterally in both the spinal and main sensory trigeminal nuclei and the spinal trigeminal tract. In the rats degeneration was found in all cases in the same ipsilateral structures as in the kittens. The amount of degeneration was relatively great in the rats, whereas it was very modest in the kittens. A somatotopical pattern was found for the degeneration both within the spinal and the main sensory nuclei. It was in agreement with what has been found in earlier studies, where other techniques have been used. By a comparison with the results of a previous study on the trigeminal nerve in the rat, where partial lesions of the ganglia had been made, it was found that the degeneration in the present study did not cover the whole area receiving primary trigeminal afferents. Possible explanations for this are discussed.
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