Jan Ygge

Cell loss in lumbar dorsal root ganglia and transganglionic degeneration after sciatic nerve resection in the rat

The effects of sciatic nerve resection on lumbar dorsal root ganglion cells and their central branches have been studied in the adult rat. A quantitative analysis of the lumbar dorsal root ganglia indicated a 15-30% cell loss on the operated side. Argyrophilia indicating transganglionic degeneration was observed in Fink-Heimer stained sections from the lumbar spinal cord and the brainstem. The areas of degeneration argyrophilia were mainly located in the medial part of the ipsilateral L2-L6 dorsal horn laminae I-IV, the tract of Lissauer, the dorsal funiculus and the gracile nucleus. A few degenerating fibers could also be observed in the ipsilateral dorsal horn laminae V and VI, and in the ipsilateral ventral horn as well as in the contralateral dorsal horn and the gracile nucleus. The results confirm and extend previous findings at other levels and in other species. This suggests that cell loss and transganglionic degeneration may be general phenomena affecting a substantial proportion of primary sensory neurons following peripheral nerve injury.

Substance P-, somatostatin- and calcitonin gene-related peptide-like immunoreactivity and fluoride resistant acid phosphatase-activity in relation to retrogradely labeled cutaneous, muscular and visceral primary sensory neurons in the rat

The distribution of several peptides in cutaneous, muscular and visceral primary sensory neurons was investigated in the adult rat. The fluorescent dye Fast blue was applied to the proximal ends of transected saphenous (cutaneous), gastrocnemius (muscular) and greater splanchnic (visceral) nerves. Sections from corresponding dorsal root ganglia were incubated for simultaneous indirect immunocytochemical demonstration of calcitonin gene-related peptide (CGRP)-, substance P (SP)- or somatostatin (SOM)-like immunoreactivity (-LI) and Fast blue. In addition, the presence of fluoride resistant acid phosphatase (FRAP)-enzyme activity (-EA) in retrogradely Fast blue-labeled saphenous and gastrocnemius nerves was investigated by subsequent enzyme cytochemical analysis. The results revealed the presence of CGRP-LI, SP-LI, SOM-LI and FRAP-EA in cell bodies of primary sensory neurons which project to the saphenous and gastrocnemius nerves. CGRP-LI and SP-LI, but not SOM-LI, were found in splanchnic sensory neurons. The vast majority of the visceral sensory neurons were found to contain CGRP-LI.

Transganglionic transport of horseradish peroxidase in primary sensory neurons

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.

Neuronal loss in lumbar dorsal root ganglia after proximal compared to distal sciatic nerve resection: a quantitative study in the rat

The effects of unilateral sciatic nerve resections at proximal (thigh) or distal (proximal calf) locations on L4-L6 dorsal root ganglion (DRG) neuronal numbers have been studied in adult rats. Proximal nerve resection gave rise to a mean DRG neuronal loss of 27%, whereas in distal lesions a mean cell loss of 7% was found. This difference in cell loss between proximal and distal sciatic nerve resections is highly significant (P less than 0.001).

Cellular Reactions on Heparin Surface-modified versus Regular PMMA Lenses during the First Postoperative Month: A Double-masked and Randomized Study Using Specular Microphotography

Specular microscopy was used for investigation of cellular reactions on the intraocular lens (IOL) anterior surface of Heparin surface-modified (HSM) versus regular polymethylmethacrylate (PMMA) lenses (Pharmacia types 700C versus 700B, respectively). The double-masked randomized study included 53 patients investigated at 1 and 4 weeks postoperatively. Giant cells were only found on control lenses and more frequently at 4 weeks. Small cells were found on both lens types, but in a higher frequency on the control lenses. The number of small cells decreased during the first 4 weeks on both the control and HSM lenses. However, those control lenses that had giant cells on their surface showed an increase in the number of small cells during the same time. The results of the current study show that HSM lenses give rise to less postoperative inflammatory cellular reactions than regular PMMA lenses.

Intercostal nerve transection and its effect on the dorsal root ganglion: a quantitative study on thoracic ganglion cell numbers and sizes in the rat

SummaryThe effect of intercostal nerve transection on the number and size distribution of thoracic spinal ganglion cells has been investigated and correlated with transganglionic degeneration (TGD) in the spinal cord dorsal horn. Unilateral transections were made of 3 or 11 consecutive intercostal nerves. Twenty to 180 days later the animals were perfused and relevant ganglia from both sides embedded in resin, serially sectioned and stained. Counts of neuronal nucleoli were made and perikaryal areas of ganglion cells measured. The number of neurons was significantly reduced on the operated side 20 days postoperatively. The cell loss increased slightly to about 35% with longer survival times. Analysis of cell size spectra showed a bilaterally symmetrical picture in normal animals. No distortions of the cell size spectrum were observed at 20 to 70 days after nerve transections. Transganglionic degeneration was found in the dorsal horn from 20 to 70 days postoperative survival, but not at 180 days. The findings indicate that TGD in the dorsal horn is related to a loss of ganglion cells in the corresponding spinal ganglion. There does not seem to be a preferential loss of any particular size class of cells.

Peripheral projections and neuropeptide coexistence in a subpopulation of fluoride-resistant acid phosphatase reactive spinal primary sensory neurons

Combined retrograde axonal tracing with the fluorescent dye Fast Blue and fluoride-resistant acid phosphatase (FRAP) histochemistry revealed that the FRAP-containing sensory neurons project to both somatic and autonomic peripheral nerves. Furthermore, the combination of indirect immunohistochemistry after colchicine treatment and FRAP histochemistry showed that a population of FRAP-containing sensory neurons are also substance P, cholecystokinin or somatostatin positive.

Nystagmus in periventricular leucomalacia

BACKGROUND/AIMS Periventricular leucomalacia (PVL) is a lesion in the immature brain involving the optic radiation. Children with PVL have visual problems including crowding, visual field defects, strabismus, and visual perceptual/cognitive deficits, together with nystagmus. They often have optic nerve hypoplasia seen either as small discs or as large cupping of normal sized optic discs. This study aimed to perform eye movement recordings in a group of children with PVL in order to characterise and classify the nystagmus. METHODS 19 children with PVL on cerebral imaging underwent eye movement recordings with the Ober-2 infrared reflection technique. RESULTS 16 of the 19 subjects had horizontal nystagmus. CONCLUSION The present study shows that nystagmus is commonly seen in children with PVL.

Visual functions in a Swedish population of dyslexic and normally reading children

Abstract Eighty‐six 9‐year old dyslexic children were carefully matched to controls with regard to age, sex, class in school, and intelligence and thorough visual functions tests and eye examinations were performed. As a group the dyslexic pupils exhibited a lower distance as well as near visual acuity both with monocular and binocular viewing. Furthermore, the dyslexic pupils had a lower contrast sensitivity at the lower and higher spatial frequencies. These differences were all statistically significant. However, no statistically significant differences between the two groups could be observed regarding refractive errors or contrast sensitivity in the middle spatial frequency range. Although some eyes were amblyopic, any severe eye anomalies or diseases were not found in any of the investigated children.

Visual and perceptual characteristics, ocular motility and strabismus in children with periventricular leukomalacia

The immature visual system is vulnerable to adverse events. Periventricular leukomalacia (PVL), an end-stage lesion after hypoxia-ischemia at gestational age 24–34 weeks affecting the visual radiation, has become a principal cause of visual impairment in children. Cerebral visual dysfunction caused by PVL is characterized by delayed visual maturation, subnormal visual acuity, crowding, visual field defects, and visual perceptual-cognitive problems. Magnetic resonance imaging is the method of choice for diagnosing this brain lesion, which is associated with optic disk abnormalities, strabismus, nystagmus, and deficient visually guided eye movements. Children with PVL may present to the ophthalmologist within a clinical spectrum from severe visual impairment in combination with cerebral palsy to only early-onset esotropia, normal intellectual level and no cerebral palsy. Optimal educational and habilitational strategies need to be developed to meet the needs for this group of children.