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Biomedical subjects

J Arvidsson

Publications and source records attributed to J Arvidsson.

At least 37 records · Page 2Linked to original sources
PubMed1993

The response of central glia to peripheral nerve injury.

Microglial and astroglial cells undergo prompt responses to peripheral motor and sensory axon injury. These responses include proliferation of microglial cells as well as hypertrophy and increased levels of glial fibrillary acidic protein around the axotomized motoneurons and in the central projection territories of peripherally axotomized sensory ganglion cells. Proliferating microglial cells migrate towards reacting motoneurons, however, without directly apposing their cell membrane. Astroglial cells, on the other hand, increase their structural interrelationship with reacting motoneurons, seemingly at the expense of some presynaptic terminals. In sensory projection areas, microglial cells phagocytose degenerating axons and terminals. Beyond these observations, the functional role of the central glial cell response to peripheral nerve injury is obscure.

Animals↗
PubMed1992

Brain stem projections of rat lumbar dorsal root ganglia studied with choleragenoid conjugated horseradish peroxidase.

Brain stem projections from each of the L1-L6 lumbar dorsal root ganglia (DRGs) were investigated in adult rats following DRG injections of choleragenoid-horseradish peroxidase. All these DRGs projected throughout the rostrocaudal extent of the gracile nucleus (Gr). Labeling from L1-L6 DRGs was transported to successively more dorsomedial areas of Gr. Investigation of the Gr projections from the DRGs revealed a somatotopic organization which was most prominent in the middle part of Gr. The cuneate nucleus showed smaller projections from all investigated DRGs. Minor projections to the internal basilar nucleus, external cuneate nucleus, medial vestibular nucleus, ventral cochlear nucleus and trigeminal sensory nuclei were also found from some of the DRGs.

Animals↗
PubMed1992

The reaction of mesencephalic trigeminal neurons to peripheral nerve transection in the adult rat.

The effects of peripheral nerve transection on mesencephalic trigeminal (MeV) neurons have been studied qualitatively and quantitatively in the rat. In the qualitative part of the study the brain stem was studied in Fink-Heimer stained sections 3-30 days after a masseteric nerve transection. Degeneration argyrophilia was observed both in the MeV tract and in the supratrigeminal and trigeminal motor nuclei, as well as in the lateral part of the brain stem reticular formation. The first signs of transganglionic degeneration (TGD) were seen 7 days postoperatively, and the amount of degeneration increased considerably with longer survival times. A quantitative analysis of the MeV nucleus was made 60 days after transection of the left masseteric nerve. This analysis showed a 10.5-22.7% reduction of cells on the side that had undergone masseteric nerve transection. The mean difference (left vs right side) was -2.4% in animals that had not been operated on. These findings show that mesencephalic trigeminal neurons with proprioceptive functions are very sensitive to peripheral nerve injury with a substantial cell loss and TGD as the result.

Animals↗
PubMed1992

The ganglionic origins and central projections of primary sensory neurons innervating the upper and lower lips in the rat.

Retrograde and transganglionic transport of horseradish peroxidase (HRP) was used to investigate the neurons innervating the upper and the lower lips and their central projections in the rat. Both the upper and the lower lips were observed to be innervated by a very large number of trigeminal sensory neurons, with their cell bodies located in the maxillary and the mandibular parts of the trigeminal ganglion, respectively. The central projections of neurons innervating the upper lip formed a long continuous column starting rostrally at midlevels of the trigeminal main sensory nucleus (5P) and extending caudally through the C1 dorsal horn, with occasional fibers reaching the C3 segment. The heaviest projections appeared in the middle portions of 5P and nucleus interpolaris (5I), as well as in the rostral part of nucleus caudalis (5C). A small but consistent projection to the solitary tract nucleus, originating from cells in the inferior vagal ganglion, was observed in the upper-lip experiments. The central projections from neurons innervating the lower lip also appeared as a long column located dorsally or dorsomedially to the projections from the upper lip. The most prominent projections from the lower lip were located in the caudal part of 5P, the middle part of 5I, and the caudal two-thirds of 5C. Sparse projections could be traced as far caudally as C4. At 5C and cervical levels, some labeling appeared contralaterally in the same location as on the ipsilateral side.

Animals↗
PubMed1992

Vision examination of children in Riyadh's handicapped children house.

Fifty-eight children with neuromuscular handicap participating in a habilitation program at Riyadh, Saudi Arabia underwent an abbreviated vision examination evaluating their visual status. Manpower, time, language and equipment constraints prevented the performance of routine, complete eye examinations for each child. This initial effort was designed to assess the subjects' vision as well as examination time, space, manpower, and any other unforeseen problems in treating this population. This vision evaluation showed that 63.7 percent had ocular findings, and only 17.2 percent had a history of previous eye examination. Currently, a program of evaluation, training and education is underway to treat these children with motor and social handicaps at the Handicapped Children House. Routine vision examination, more complete than undertaken with this study, should be instituted, incorporating ocular history, external examination, refraction, dilated ophthalmoscopy, slit lamp with further evaluation and treatment of those children with findings.

Child↗
PubMed1991

Central projections of primary sensory neurons innervating different parts of the vibrissae follicles and intervibrissal skin on the mystacial pad of the rat.

The cell bodies and central projections of neurons innervating the vibrissae follicles and adjacent skin in the rat were investigated by retrograde and transganglionic transport of HRP. The cell bodies of neurons innervating the vibrissa follicle via the deep vibrissa nerve (DVN) were the largest, followed by those innervating the follicle via the superficial vibrissa nerve (SVN). The smallest cell bodies were those innervating the intervibrissal skin. The DVN neurons terminated centrally as an almost uninterrupted column through the trigeminal sensory nuclear complex. The DVN projections to nucleus caudalis and C1 dorsal horn were entirely restricted to laminae III, IV, and V. Besides the projections to lamina V, the DVN projections were strictly localized somatotopically at all levels replicating the peripheral organization of the vibrissae. The SVNs projected sparsely to midlevels of the main sensory nucleus but not to nuclei oralis and interpolaris. The main SVN projections appeared in laminae I-III of nucleus caudalis. In addition, a small projection to lamina V was observed. The projections to laminae II and III were organized mediolaterally in a similar way as the DVN projections; those to laminae I and V were less restricted. The intervibrissal skin neurons projected sparsely to the caudal main sensory nucleus and to the border between nuclei oralis and interpolaris. The projections to nucleus caudalis were restricted to laminae I-III and V and were organized in a similar way as the SVN projections.

Afferent Pathways↗
PubMed1991

Ultrastructural changes in the gracile nucleus of the rat after sciatic nerve transection.

Ultrastructural changes in the gracile nucleus of the rat have been examined after peripheral nerve injury. The sciatic nerve of adult rats was transected at mid-thigh level, and after survival times ranging from 1 day to 32 weeks sections from the gracile nucleus were prepared for electron microscopic examination. Unoperated animals served as controls. Atypical profiles were regularly observed in the experimental cases at post-operative survival times from 3 days up to 32 weeks. It was sometimes not possible to classify these as preterminal axons or terminals, because synaptic contacts could not be identified. The two most common changes throughout the entire post-operative period were greatly expanded myelinated axons, or unmyelinated profiles containing numerous mitochondria, osmiophilic dense bodies and vacuoles. Atypical profiles were occasionally observed in unoperated control animals. The results clearly show that various types of degenerative changes occur in the gracile nucleus after peripheral nerve injury. These changes differ markedly from previously described transganglionic changes in other systems. It cannot be excluded that some of the changes reflect growth-related reactions, although the typical features of axon regeneration could not be found.

Animals↗
PubMed1991

Anterograde horseradish peroxidase tracing and immunohistochemistry of trigeminal ganglion tooth pulp neurons after dental nerve lesions in the rat.

The peripheral reorganization of pulpal nerves after tooth injury was studied, in the rat, with anterograde horseradish peroxidase tracing techniques, and combined retrograde Fluorogold tracing and immunohistochemistry was employed to examine the effects of inferior alveolar nerve lesions or tooth injury on some cytochemical characteristics of pulpal trigeminal ganglion nerve cells, namely content of substance P, calcitonin gene-related peptide and the ganglioside GM1 (binding subunit of cholera toxin), as well as affinity to RT 97 (antibody to neurofilament protein) and the lectin Griffonia simplicifolia isolectin I-B4. Anterograde horseradish peroxidase tracing demonstrated that pulpal nerves either disappear or reinnervate novel targets after loss of pulpal tissue. There were no obvious signs of neuroma formation. Retrograde Fluorogold labelling with immunohistochemistry showed that after inferior alveolar nerve lesions with subsequent regeneration, a much higher proportion of Fluorogold cells (15%) were substance P-positive compared to normal (2%). In addition, 3% of the cells were Griffonia simplicifolia isolectin I-B4-positive. Such cells were very rare in controls. Proportions of calcitonin gene-related peptide-, GM1- and RT-97-positive cells were normal. After tooth lesions, the proportions of Fluorogold-positive substance P-, Griffonia simplicifolia isolectin I-B4-, GM1- and RT 97-labelled cells were similar to controls, while the proportion of calcitonin gene-related peptide-positive neurons was reduced. The results show that pulpal deafferentation may change the long-term cytochemical characteristics of affected trigeminal ganglion neurons.

Animals↗
PubMed1990

Retrograde axonal transport of mercury in primary sensory neurons innervating the tooth pulp in the rat.

The pulp cavity of the first upper molar was exposed unilaterally in adult rats with a dental drill and about 1 microliter of mercuric chloride was injected into the coronal pulp. The rats were killed after 1-24 days and frozen sections from the trigeminal ganglia were subjected to silver acetate autometallography for demonstration of mercury. Mercury was found to have accumulated in neurons of the ipsilateral trigeminal ganglion by retrograde axonal transport. The possible implications of this finding are discussed.

Afferent Pathways↗
PubMed1990

Ultrastructural observations of non-selective effects of ricin treatment (RCA-120) in the rat dorsal root ganglion.

The effects of ricin (RCA-120) on non-injected dorsal root ganglion (DRG) cells, sharing the same DRG as the injected ones, were studied after ricin injections into the tibial nerve and B-HRP injections into the peroneal nerve. Numerous DRG cells containing B-HRP reaction product and exhibiting signs of advanced degeneration were observed. The findings suggest that ricin may be released from dying injected DRG neurons and taken up by adjacent non-injected DRG cells, which subsequently degenerate.

Animals↗
PubMed1990

Central projections of C4-C8 dorsal root ganglia in the rat studied by anterograde transport of WGA-HRP.

Injections of WGA-HRP were made in the rat C4-C8 dorsal root ganglia (DRGs) individually to study the central projections and their relations to each other. The main dorsal horn projections from these DRGs to the dorsal horn lamina II extended for about two segments rostrally and caudally to the injected DRG, whereas the projections to laminae I, III, and IV were less restricted rostrocaudally. Comparisons of the dorsal horn projections from the DRGs investigated indicated a tendency for a somatotopic organization, which was most prominent in lamina II. Labeled central branches from the C4-8 DRGs could be traced in the dorsal column as far caudally as 12-17 segments caudal to the level of entrance. Most of these fibers appeared to end in the medial dorsal horn base, including the column of Clarke. Labeling of primary afferents in the ventral horn generally extended for at least 3-4 segments rostral and caudal to the level of the injected DRG. Projections to the central cervical nucleus were most prominent from the C4 DRG and gradually became less prominent from the more caudal DRGs. Heavy projections to the cuneate nucleus (Cun) originated from the C7 and C8 DRG, whereas those from the C4-C6 DRGs were less extensive. The Cun projections from the different DRGs appeared to overlap, and the same was true for the projections to the external cuneate nucleus. Projections to the gracile nucleus, the vestibular nuclear complex, including nucleus X, and to trigeminal sensory nuclei were seen from all DRGs investigated.

Afferent Pathways↗
PubMed1990

Ultrastructural changes of the central scalloped (C1) primary afferent endings of synaptic glomeruli in the substantia gelatinosa Rolandi of the rat after peripheral neurotomy.

Fine structural changes were observed in the dark scalloped central C1 terminals of type I synaptic glomeruli in spinal cord segments C6-C7 of the rat 3 days after cutting the three main forelimb nerves. Twenty-six per cent of the C1 terminals occurring on the ipsilateral side showed a lighter appearance due to a decrease in the number of synaptic vesicles. The number of synaptic vesicles per unit section area was only 42% of that present in normal C1 terminals on the contralateral side. The number of synaptic contacts of C1 terminals with the profiles surrounding them in each glomerulus was diminished and glial envelopment was increased to 15% of C1 terminal contour. Up to day 12, vesicle and synaptic losses were gradually aggravated and glial apposition was increased, but no obvious signs of glial engulfment were observed. From day 3 to day 12, altered C1 terminals increased in number, while those that appeared normal decreased. The latter had disappeared at day 12 and the altered ones at day 15, and from this stage type I glomeruli were no longer present on the treated side. The lack of electron-dense degenerative bouton changes characteristic of Wallerian degeneration offers an explanation for the lack of or minimal amount of argyrophilic structures which has been found consistently in the substantia gelatinosa during transganglionic degeneration. The gradual decay of the C1 terminals raises the question of their fate. Future studies with the use of a stable marker might provide an answer.

Afferent Pathways↗
PubMed1990

Delayed-onset dyskinetic 'cerebral palsy--a late effect of perinatal asphyxia?

A 12-year-old girl, born full term after severe pre- and peripartal asphyxia, with transient abnormal newborn neurology and slight motor development deviations but no cerebral palsy syndrome, is described. At the age of 5, she developed a slowly progressive dyskinetic hemisyndrome, initially uncoordinated hyperkinetic movements in her left arm, dystonic posturing then supervened. Since the age of 11, her right side had also slowly become involved. As extensive examinations excluded other causes, it is concluded that this case represents a delayed onset dyskinetic 'CP-syndrome' subsequent to a postanoxic non-progressive insult to the basal ganglia, but with a well compensated functional integrity before the age of 5.

Asphyxia Neonatorum↗
PubMed1990

Diurnal variation of carbamazepine and carbamazepine-10,11-epoxide in plasma and saliva in children with epilepsy: a comparison between conventional and slow-release formulations.

In order to overcome the problems of interdosage fluctuations of body fluid concentrations of carbamazepine, a slow-release formulation has been developed. In an open, controlled, within-patient study, the diurnal plasma concentrations of carbamazepine and its 10,11-epoxide were measured in 25 epileptic children first treated with conventional carbamazepine tablets (Tegretol) and then with the Tegretol slow-release preparation. The diurnal plasma concentration curves during treatment with the slow-release formulation showed significantly less variation over 24 hours than during treatment with the ordinary preparation, as measured by the fluctuation index. Mean concentration values also differed significantly, which is explained by a somewhat reduced bioavailability (22% less) of the slow-release formulation. There were no differences in efficacy and tolerability between the two formulations, but there was a clear-cut reduction of reported side effects, especially tiredness, on treatment with the slow-release formulation. For that reason, the slow-release formulation should be a major advantage in treating children with epilepsy, in order to avoid interference with cognitive functions. In 12 children, simultaneous measurements of the concentration of carbamazepine and its epoxide in saliva were made and compared with the plasma values. As expected, the concentration curves corresponded, indicating that saliva sampling is an appropriate alternative for monitoring the concentration of carbamazepine. All children remained on the slow-release preparation after the trial and were followed up for 12 months or more.

Adolescent↗
PubMed1990

Ultrastructural observations on transganglionic degeneration in trigeminal primary sensory neurons in the neonatal rat.

Transganglionic degeneration was studied ultrastructurally in the trigeminal nucleus caudalis of newborn rats 2-6 days after a transection of the infraorbital nerve. Darkened degenerating terminals containing more or less numerous vacuoles and darkened unmyelinated axons were observed already 2 days postoperatively, but became more frequent at 3 days survival, and again less frequent at 6 days survival. Degenerating myelinated axons were most frequent 6 days postoperatively. Another conspicuous finding was the appearance of degenerating cells, in less advanced stages interpreted as being neurons.

Animals↗
PubMed1990

A light microscopical study of transganglionic degeneration in young rats of different ages.

Transganglionic degeneration (TGD) has been studied in the trigeminal nucleus caudalis of young rats of different ages with the aid of the Fink-Heimer technique at various intervals following peripheral nerve transection. In addition, the occurrence of TGD was examined in adult rats after retransection of a peripheral nerve originally transected at birth. The results showed no degeneration argyrophilia indicating TGD in the rats operated at birth regardless of the survival time. Small amounts of TGD appeared in rats operated at an age of about one week and surviving one to 4 weeks. Similar results were obtained in rats operated at 17-26 days of age and surviving for around one week, whereas longer survival times resulted in an increased amount of TGD. These findings suggest that nonargyrophilic forms of TGD predominate in the youngest rats, since other studies have demonstrated a substantial cell loss in the trigeminal ganglion of the neonatal rat following peripheral nerve injury. No degeneration argyrophilia was observed in the rats which were subjected to a retransection of the peripheral nerve when grown to adults. This might be a reflection of a severe cell loss after the initial transection and/or that regenerating neurons will react more like immature neurons.

Aging↗
PubMed1989

Dose- and time-dependent selective and non-selective effects of ricin (RCA 120) on rat primary sensory neurons.

The distribution of degenerating fibers in the spinal cord was studied in Fink-Heimer-stained sections following treatment of the tibial nerve with ricinus communis agglutinin (RCA 120). The ricin was either injected into the nerve or applied in a capsule on the transected nerve. Short survival times and low doses of ricin resulted in degeneration in somatotopically appropriate parts of the medial dorsal horn. Longer survival times and higher doses resulted in degeneration which progressively expanded into inappropriate areas in the central and lateral parts of the dorsal horn and in deeper laminae regardless of the mode of application. Furthermore, the effect of a ricin injection into the tibial nerve on transganglionic transport of choleragenoid horseradish peroxidase (B-HRP) in the peroneal nerve was studied following a simultaneous or delayed B-HRP injection. A simultaneous ricin and a B-HRP injection resulted in primary afferent HRP labeling in the gray matter, regardless of the dose of ricin. Following a delayed B-HRP injection almost no primary afferent labeling was seen in the gray matter, unless a very low dose of ricin was injected. This study shows that treatment of a peripheral nerve with a high dose of ricin and a long survival time may result in a considerable non-selective degeneration of fibers in the spinal cord. A selective degeneration may, however, be obtained by using lower doses or shorter survival times.

Animals↗