Biomedical subjects

H Veldman

Publications and source records attributed to H Veldman.

At least 37 records · Page 2Linked to original sources

PubMed1994

Features of the Guillain-Barré syndrome in mice following intraperitoneal injection of patient serum.

Intraperitoneal injection of serum from a patient with the Guillain-Barré syndrome (GBS) produced GBS-like signs in mice: inadequate respiration and weakness in the legs. We studied the clinical, electrophysiological and pathological features of these mice. Three groups of three mice were injected with patient serum from days 6, 10 and 15 after onset of neurological symptoms. GBS-like signs in mice were observed only with serum from day 6 and improved within 48 h. When serum was frozen and thawed more than once no signs were seen. Electrophysiological measurements of the sciatic nerves of injected and control mice were done before and after serum injection. Five days after injection of patient serum of day 6, the mice showed a significant decrease in the ratio between CMAP amplitude from proximal and distal stimulation and increase in H-M interval from proximal stimulation. These electrophysiological changes returned to normal within 12 days. The sciatic nerve showed no morphological abnormalities. Our results indicate that the observed GBS-like signs in mice are caused by peripheral nerve dysfunction.

Adult↗

PubMed1994

Elimination of superfluous neuromuscular junctions in rat calf muscles recovering from botulinum toxin-induced paralysis.

In order to determine the fate of the superfluous neuromuscular junctions (NMJs) formed during the course of botulinum toxin (BoTx)-induced paralysis, we have quantified the change in the total length of the nerve muscle contact area(s) following BoTx injection into rat calf muscles. The results indicate that: (1) at least some of the superfluous NMJs are eliminated following muscle recovery; (2) synapse elimination is a slow process, as 4 months after recovery it was not yet complete; (3) muscles with different content of type I and II fibers follow a different time course during synapse formation and elimination. We further investigated the possibility that the neural cell adhesion molecule (NCAM) would be the element whose loss from the NMJ might play a role in synapse elimination. Using immunofluorescence and immunoelectron microscopy we show that NCAM is exclusively localized between nerve terminals and Schwann cells and not between nerve terminals and muscle. This localization was maintained throughout paralysis and following recovery, suggesting that NCAM does not play a role in synapse elimination.

Animals↗

PubMed1994

Basic fibroblast growth factor immunoreactivity in the peripheral motor system of the rat.

We have used immunohistochemistry and electron microscopy to investigate the distribution of basic fibroblast growth factor (bFGF) in the peripheral motor system of the adult rat. In the lumbar segments of the spinal cord, bFGF immunoreactivity (bFGF-I) was seen in motor neurons and glial cells but not in axons. The neuronal immunostaining was seen as two or three intensely fluorescent spots in the nuclei with weak and more diffuse staining of the perinuclear cytoplasm. In the sciatic nerve, bFGF-I was seen in Schwann cells with strong intensity at the nodes of Ranvier. Axonal immunostaining could not be detected. At the electron microscopic level, the intense nodal immunostaining of Schwann cells was confirmed and was found to be localized to the Schwann cell membrane at the nodal gap. The intensity of staining decreased with distance from the node. In the soleus and gastrocnemius muscles, bFGF-I was seen at the motor endplates in sites corresponding to the motor nerve terminals in addition to faint staining within the muscle fibers. Electron microscopy showed that bFGF-I was localized within the nerve terminals. Histochemical localization of bFGF in the peripheral motor system is compatible with the functions ascribed for this protein in this system.

Animals↗

PubMed1994

Insulin-like and fibroblast growth factors in spinal cords, nerve roots and skeletal muscle of human controls and patients with amyotrophic lateral sclerosis.

Insulin-like growth factors (IGF-I and IGF-II) and fibroblast growth factors [acidic FGF (aFGF) and basic FGF (bFGF)] are trophic for motor neurones in vitro and (in laboratory animals) in vivo. An immunohistochemical investigation was performed on the distribution of these factors in the neuromuscular system of control patients and patients with amyotrophic lateral sclerosis (ALS). Comparisons were made with rat tissue. IGF-I immunoreactivity (IGF-I-IR) was seen in motor neurone cell bodies and axons, astroglia and Schwann cells, and in muscle fibres. IGF-II-IR was weak in all these cells. aFGF-IR was present in motor neurone cell bodies and axons, oligodendroglia and muscle fibres, but was not demonstrable in Schwann cells. bFGF-IR was present in motor neurone cell bodies and axons, and in astroglia, but was not seen in Schwann cells or muscle fibres. The distribution of the IGFs and FGFs in material from motor neurone disease (MND) and controls was similar. A role for any of these factors in the etiology of MND is, therefore, unlikely. IGF-I-IR and aFGF-IR were stronger in type II than in type I muscle fibres and were increased in denervated fibres. Species differences were found for IGF-I and bFGF. The function of these factors is apparently not entirely similar in humans and rats.

Adult↗

PubMed1994

GAP-43 and p75NGFR immunoreactivity in presynaptic cells following neuromuscular blockade by botulinum toxin in rat.

Peripheral nerve lesion results in changes in protein expression by neurons and denervated Schwann cells. In the present study we have addressed the question whether similar changes take place following functional denervation. Using immunohistochemistry and immunoelectron microscopy we examined changes in growth-associated protein (GAP-43) and low-affinity nerve growth factor receptor (p75NGFR) in rat gastrocnemius muscle following botulinum toxin-induced paralysis. GAP-43 and p75NGFR were selected because they are not expressed by mature intact motor neurons or Schwann cells, but are expressed following nerve lesion in both motor neurons and denervated Schwann cells. In control muscle, GAP-43 and p75NGFR immunoreactivity was seen only in nerve fibres near blood vessels. Two weeks after toxin injection, GAP-43 immunoreactivity could be seen at the motor endplates and in axons. Intensity of staining increased with longer survival and reached a peak between 4 and 8 weeks post-injection. Ultrastructurally, GAP-43 immunoreactivity was confined to nerve terminals and axons, whereas Schwann cells remained negative. Immunostaining for p75NGFR also increased following toxin injection and was detected in some terminal Schwann cells and in perineurial cells of small nerve fascicles near the paralyzed target cells, but not in axons. These results show that changes in expression of GAP-43 in motor neurons following functional denervation closely resemble the changes following anatomical interruption of nerve-muscle contact. GAP-43 was not expressed in Schwann cells, indicating that its upregulation in these cells is induced by loss of axonal contact or nerve degeneration products. There is no support for a role of p75NGFR in incorporation of neurotrophins in axons. The restriction of p75NGFR expression to terminal Schwann cells and perineurial cells in close proximity to the paralyzed target suggests a role for a target-derived signal or, alternatively, macrophages in eliciting this expression.

Animals↗

PubMed1994

Protection against cisplatin induced neurotoxicity by ORG 2766: histological and electrophysiological evidence.

Prolonged administration of the anti-tumor agent cisplatin may cause a neuropathy in patients. In an animal model, too, neurotoxicity, as evidenced by a decrease in H-related sensory nerve conduction velocity (SNCV), can be induced by repetitive injections of cisplatin. In an attempt to further the insight into the effects of cisplatin on the peripheral nervous system a combined electrophysiological and histomorphological investigation was performed on 2 groups of 6 rats, treated with cisplatin for 7.5 weeks, and a control group (n = 6). Concomitant administration of ORG 2766, an ACTH(4-9) analog, was previously shown to prevent cisplatin neurotoxicity in this model and more recently in patients as well. One group of rats was therefore co-treated with this peptide during the complete treatment period. A marked decrease in SCNV was observed in cisplatin/saline treated rats, but not in cisplatin/ORG 2766 treated rats. Though no statistically significant difference was seen in the total number of myelinated fibers in the sural nerves of cisplatin treated rats, a decrease in the proportion of thick myelinated fibers was present in the cisplatin/saline treated rats. This shift in fiber distribution was absent in ORG 2766 co-treated animals. Mean internodal distances and g-ratios were not affected, and signs of axonal degeneration, or de- or remyelination were not observed.

Adrenocorticotropic Hormone↗

PubMed1993

Development of innervation of skeletal muscle fibers in man: relation to acetylcholine receptors.

The aim of this study was to establish the time scale of developmental changes in innervation of skeletal muscle fibers in man. Specimens of thigh and intercostal muscle from 19 embryos and 18 infants were examined with histological methods which enabled the discrimination between fetal (gamma) and adult (epsilon) types of acetylcholine receptors (AChRs). At 8 weeks of development, AChRs were distributed diffusely in the myotube membranes. Following onset of innervation in approximately the ninth week the length of the AChR positive area diminished and reached its shortest size at the sixteenth developmental week. At the sixteenth and eighteenth week some nerve terminals opposed the muscle membrane outside the AChR positive area. Decrease in the number of nerve terminals, strongly suggesting elimination of polyneuronal innervation, started in the sixteenth week and was completed in the twenty-fifth week. This fetal (gamma) type of AChR could no longer be demonstrated after the thirty-first week. The length of the end-plates as determined by the presence of AChRs increased again in the last week before birth and reached a plateau size by the end of the first year after birth. It is concluded that in man the transition from poly- to mononeuronal innervation takes place between the sixteenth and twenty-fifth weeks of development. The evidence available suggests that the retraction of nerve terminals is preceded by loss of AChRs from the muscle membrane facing the terminals. There is no relationship between retraction of nerve terminals and the switch from fetal to adult type of AChR. The size of the presynaptic apparatus changes little after the first year of life.

Child↗

PubMed1993

Inflammatory cells in the peripheral nervous system in motor neuron disease.

We examined post-mortem material of the peripheral nervous system of 26 cases of motor neuron disease (MND) for the presence of lymphocyte subsets and macrophages. Findings were quantified and compared with those in control nerves. Lymphocytes in chronic and acute axonal degeneration were studied in sural nerve biopsy and animal material. Signs of demyelination were studied in MND and controls with infiltrates of T cells. A few T lymphocytes were scattered diffusely within the fascicles. The numbers did not differ between MND and controls. About half of the T cells was positive for CD45RA, the other half being positive for CD45RO. T cells were negative for CD25, CD54 and major histocompatibility complex (MHC)-class II. There were hardly any B lymphocytes. The numbers of lymphocytes in nerves with and without axonal degeneration did not differ. Increased MHC class II expression was present on denervated Schwann cells and macrophages in MND and in sural nerves with axonal degeneration. Macrophages were increased in number and in size, both in MND and in control material with axonal degeneration. No signs of demyelination were present either in MND or in controls. It is concluded that a T cell-mediated process in peripheral nerves in MND is very unlikely.

Adolescent↗

PubMed1992

Deficiency of acetylcholine receptors in a case of end-plate acetylcholinesterase deficiency: a histochemical investigation.

A young boy is described who, since early infancy, suffered from weakness of predominantly proximal limb muscles. Electromyography revealed impairment of neuromuscular transmission. There were no antibodies against acetylcholine receptors. The amplitude of miniature end-plate potentials was reduced. Neuromuscular junctions showed somewhat coarse postsynaptic junctional folds and degeneration products in the synaptic clefts and in postsynaptic areas. Using qualitative and semiquantitative histochemical methods, at light- and electronmicroscopical levels, acetylcholinesterase (AChE) activity and acetylcholine receptors (AChRs) were demonstrated to be deficient. This patient demonstrates that the clinical picture of congenital myasthenia may closely resemble a congenital myopathy. The findings provide evidence that AChR deficiency offers protection from some of the effects of AChE deficiency. The clinical features of AChE deficiency depend, not only on the level of residual enzyme activity, but also on the degree of AChR reduction, if present.

Acetylcholinesterase↗

PubMed1992

Secondary changes of the motor endplate in Lambert-Eaton myasthenic syndrome: a quantitative study.

Underlying the Lambert-Eaton myasthenic syndrome (LEMS) is a decrease in the release of the neurotransmitter acetylcholine. Only few reports on light and transmission electron microscopical observations of motor endplates in LEMS are available and changes reported so far differ from those found in experimental blocking of acetylcholine release. We performed a quantitative study on intercostal muscle biopsies of five patients. The main light microscopical finding was an enlargement of the area of contact between nerve and muscle, which was interpreted as a compensatory phenomenon. At the ultrastructural level we found the mean postsynaptic area and membrane length of the neuromuscular junctions to be decreased, putatively due to small postsynaptic regions of newly created neuromuscular junctions. The secondary changes in LEMS endplates as seen in this study are similar to those reported in experimental blocking of acetylcholine release.

Aged↗

PubMed1992

Congenital oculo-bulbar palsy.

A girl developed progressive weakness of bulbar and ocular muscles starting before the age of two years. Electromyography revealed a widespread subclinical myopathy. An intercostal muscle biopsy showed complex abnormalities including occasional neurofilamentous accumulations and honeycomb-like membranous material in terminal axons. Endplates were small and some secondary synaptic clefts were abnormally deep. Acetylcholine receptors extended unusually deeply into the clefts of the junctional folds. Muscle fibres showed subsarcolemmal vacuolation at some places. This form of congenital oculo-bulbar palsy does not appear to have been described previously.

Axons↗

PubMed1991

Nerve growth factor receptor immunostaining in the spinal cord and peripheral nerves in amyotrophic lateral sclerosis.

In animal experiments, nerve transection is followed by expression of nerve growth factor receptors (NGFR) on Schwann cells of both motor and sensory nerve fibres distally to the site of the lesion. To determine whether denervated Schwann cells in amyotrophic lateral sclerosis (ALS) similarly express NGFR, a study was made of post-mortem material of peripheral nerves and ventral roots from ALS cases and age-matched controls, using immunolabelling methods. Dorsal roots and spinal cords were also examined for the presence of NGFR. In all the ALS cases and controls, NGFR immunostaining was seen in the outer layer of vessel walls, perineurial sheaths, connective tissue surrounding fascicles in nerve roots and in the substantia gelatinosa of the spinal cord. In ALS, NGFR staining was also present in the Schwann cells of degenerated nerve fibres in mixed peripheral nerves, in ventral roots and, to a lesser extent, in dorsal roots. NGFR immunoreactivity was also seen in elongated cells extending from the perifascicular connective tissue into the nerve fascicles. It is concluded that denervated Schwann cells in ALS express NGFR and that NGFR immunostaining on Schwann cells may be used as an indicator of axonal degeneration. The NGFR labelling in the dorsal roots supports the notion that ALS is not a pure motor syndrome.

Amyotrophic Lateral Sclerosis↗

PubMed1990

Schwartz-Jampel syndrome: I. Clinical, electromyographic, and histologic studies.

In a new, typical case of Schwartz-Jampel syndrome (SJS) the origin of the disorder was found to be purely myogenic. Concentric needle EMG showed abundant and persistent spontaneous activity, maximal at insertion, and uninfluenced by local curarization. Single-fiber EMG showed rather stable, sometimes intermittent, discharge series with occasional amplitude and/or frequency fluctuations. It could be demonstrated that this activity did not consist of complex repetitive discharges, but of independent activity of individual muscle fibers. This contrasts with findings by other investigators that have been published in this journal. Light microscopic studies of quadriceps and intercostal muscles showed no abnormalities, whereas electron-microscopic findings were in accordance with earlier studies in SJS. Endplate analysis revealed no specific changes; the postsynaptic structures gave the impression of an accelerated-maturation.

Abnormalities, Multiple↗

PubMed1990

Morphological changes in the human end plate with age.

We carried out a light and electron microscopic study on end plates and related structures in external intercostal muscles from subjects aged between 4 and 77 years. Light microscopically end plates maintained the same size, did not increase in number and showed no sprouting of terminal axons, all indicating that major compensatory histological changes to maintain adequate neuromuscular transmission with age were not required. At the ultrastructural level end plates became more complex mainly at the postsynaptic side. The latter included increased length and branching of the postsynaptic membrane with enlargement of the postsynaptic area, and degeneration of junctional folds. However, some neuromuscular junctions (NMJs) showed little branching of the postsynaptic membrane, even in old age. At the presynaptic side nerve terminals with an irregular shape were noted in the aged. Schwann cell processes were seen to intrude into the primary synaptic cleft. From these data we suggest that degeneration of the postsynaptic membrane with consequent focal denervation of NMJs is a primary event in the age-related changes of end plates. The muscle fibres showed a minor degree of type grouping in old age doubtless due to loss of motor neurons with age.

Adult↗

PubMed1990

Detection of platelet activation with monoclonal antibodies and flow cytometry. Changes during platelet storage.

To investigate whether changes in platelet condition during platelet storage correlate with an altered expression of platelet membrane proteins, the binding of monoclonal antibodies (MoAbs) to fresh platelets was compared with MoAbs' binding to thrombin-activated platelets and to platelets stored as platelet concentrates. The MoAbs included antibodies against the platelet glycoprotein (GP) IIb/IIIa complex and against two activation-dependent antigens, one of which was a component of the internal platelet alpha-granule membrane (GMP 140) and the other of which was a 53-kD protein derived from platelet lysosomes. The binding of MoAbs to platelets fixed with 1 percent paraformaldehyde was measured by flow cytometry. In thrombin-activated platelets, a threefold increase was found in the expression of GP IIb/IIIa over that in fresh platelets. The binding of the activation-dependent MoAbs increased from 2 to 3 percent to 70 to 80 percent of the platelets. Storage of platelet concentrates for 5 days resulted in a 60 percent increase in GP IIb/IIIa expression compared to Day 0 and increased binding of the MoAbs directed against GMP-140 from 3 to 16 percent and against the 53-kD protein from 2 to 8 percent of the platelets, respectively. These changes correlated with modifications in platelet morphology (decrease in swirling), leakage of lactate dehydrogenase, and release of beta-thromboglobulin. These data indicate that platelets become activated and are damaged during the storage of platelet concentrates.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗

PubMed1989

A light and electron microscopical study of B-50 (GAP-43) in human intramuscular nerve and neuromuscular junctions during development.

The growth associated protein B-50 (GAP-43) is demonstrated in human intramuscular nerves and neuromuscular junctions by light microscopy and electron microscopy. Nearly all fetal endplates are shown to be immunoreactive for B-50. The percentage of B-50 positive endplates decreases significantly during the peri- and neonatal period, but in children and adults a low percentage of B-50 positive endplates remains present. These data indicate that also in the human peripheral nervous system the expression of B-50 is developmentally regulated.

Adult↗

PubMed1988

A myasthenic syndrome with congenital paucity of secondary synaptic clefts: CPSC syndrome.

Two cases of a newly recognized myasthenic syndrome were investigated (CPSC syndrome). The course of the disease was observed for periods of 6 and 3 years. In infancy, exacerbations of the symptoms occurred during febrile illness, but thereafter the clinical course was stable and the children appeared to be only slightly handicapped. Biopsies were taken from the intercostal muscle in both patients. Microelectrode studies revealed small Mepp amplitudes. Light microscopy demonstrated predominance of type I fibers and focal type-grouping. There was a lowered cholinesterase activity and frequent branching of preterminal axons. Electron microscopy revealed that there were few, if any, folds of the postsynaptic membrane and that there were no signs of degeneration. Methods for localization of acetylcholine receptors (AChR) revealed a deficiency and altered distribution of AChRs at these postsynaptic membranes and the occurrence of extrajunctional AChRs in some muscle fibers. It is concluded that the syndrome is a clinicopathological entity, characterized morphologically by a congenital paucity of secondary synaptic clefts (CPSC syndrome).

Child↗

PubMed1988

Histological investigations of muscle atrophy and end plates in two critically ill patients with generalized weakness.

We describe pathological alterations at the light microscopical and ultrastructural level of motor end plates and muscle fibres in 2 critically ill patients with generalized muscular atrophy and weakness. Axonal degeneration of intramuscular nerve fibres was not conspicuous. The sural nerve in one patient showed only minor abnormalities. There was a marked atrophy of type 1 and especially type 2 muscle fibres. Nodal and ultraterminal nerve sprouts were seen in both biopsies. Motor end plates showed features of regeneration. They were enlarged in one patient. This patient was treated for a prolonged period with vecuronium bromide. Pharmacological denervation may explain the presence of fibrillation potentials, and, partially, of the histological abnormalities. Another factor which must be considered is inhibition of neuromuscular transmission by antibiotics. In addition to disuse atrophy and a minor degree of axonal neuropathy, the production of muscle proteolytic factors may be involved in the rapidly occurring massive loss of muscle fibre size in critically ill patients.

Atrophy↗