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Biomedical subjects

J Schoenen

Publications and source records attributed to J Schoenen.

At least 19 recordsLinked to original sources
PubMed1992

Experimental acute traumatic injury of the adult rat spinal cord by a subdural inflatable balloon: methodology, behavioral analysis, and histopathology.

We describe an experimental model to produce closed traumatic injuries to the spinal cord of adult rats. This model uses an inflatable balloon that is introduced in the dorsal subdural space and moved to a location rostral to the laminectomy site. The spinal cord trauma can be graded by varying either the duration of compression or the volume of saline used to inflate the balloon. The locomotor deficit of animals with various degrees of injury has been assessed at increasing delays after trauma. The parameters generating transient or definitive deficits of varying intensity were defined. Some injured animals underwent nuclear magnetic resonance imaging. Detailed histopathological studies demonstrated that the extent of the spinal lesion was significantly correlated with the physical parameters of compression and with the severity of the behavioral deficit.

Animals↗
PubMed1992

MRI-pathological correlations in acute traumatic central cord syndrome: case report.

Ante- and post-mortem MRI and detailed pathological examination were performed in a patient with a typical acute traumatic central cord syndrome (ATCCS) after a minor hyperextension injury to the neck who died 60 h later from heart failure. T2-weighted MRI showed a central hyperintense area at C3-4. There were disc protrusions, but no vertebral fracture or displacement. Histopathology disclosed severe axonal swelling and oedema in the dorsolateral fasciculi and, to a lesser degree, in the dorsal columns. In addition, an area of recent necrosis was found in the right anterior horn at C4-5. These findings suggest that the pathological hallmark of typical ATCCS is mechanical axonal disruption at a segmental level, but that more severe trauma may be accompanied by tissue destruction.

Axons↗
PubMed1992

Percutaneous magnetic stimulation of the motor cortex in migraine.

We have used transcranial magnetic stimulation of the motor cortex interictally in 12 patients with unilateral classic migraine with sensorimotor auras and 10 patients with common migraine and unilateral headache. In classic migraine, the threshold of activation of the FDI muscle by the cortical stimulus was significantly increased on the side of the auras, when compared to the unaffected side (P less than 0.01) and to normal subjects (P less than 0.01). The amplitude of EMG responses was also reduced in FDI on the affected side when compared to normals (P less than 0.02). Responses obtained in common migraine patients were normal on both sides. We suggest that some permanent subclinical dysfunction of the motor cortex might play a role in the pathogenesis of attacks of classic migraine with sensorimotor auras.

Adolescent↗
PubMed1992

In vitro and in vivo modulation of 5-hydroxytryptamine-, thyrotropin-releasing hormone- and calcitonin-gene related peptide-like immunoreactivities in adult rat sensory neurons.

In a previous work we have shown that culturing adult rat dorsal root ganglia neurons modifies their neurotransmitter phenotype in such a way that cultured neurons synthesize transmitters that are not found in situ, while several other transmitters are expressed in a much higher percentage of neurons in culture than in situ [Schoenen J. et al. (1989) J. Neurosci. Res. 22, 473-487]. The aim of the present study was to investigate the origin and the nature of the relevant environmental signals that allow this plasticity to be expressed, focusing on three neurotransmitters: 5-hydroxytryptamine, thyrotropin-releasing hormone and calcitonin-gene related peptide. The main results can be summarized as follows: (1) culturing cells in fetal calf serum or on feeder layers of astrocytes, Schwann cells or fibroblasts partially inhibits the serotoninergic phenotype of dorsal root ganglia neurons; (2) in vivo disconnection of dorsal root ganglia from their spinal targets but not from their peripheral or supraspinal targets induces a significant increase of the percentage of 5-hydroxytryptamine- and thyrotropin-releasing hormone-positive neurons in disconnected ganglia; (3) growth factors such as ciliary neuronotrophic factor or basic fibroblast growth factor but not nerve growth factor repress 5-hydroxytryptamine and calcitonin gene-related peptide immunoreactivity in cultured sensory neurons. In conclusion, neurotransmitter gene expression of adult dorsal root ganglia neurons is controlled by complex influences. Our data suggest that thyrotropin-releasing hormone and 5-hydroxytryptamine gene expression are tonically repressed in vivo by factors originating from the spinal segmental level and that growth factors such as ciliary neurotrophic factor or basic fibroblast growth factor could be potential vectors of this repressing effect.

Animals↗
PubMed1992

Unilateral facial pain as the first symptom of lung cancer: are there diagnostic clues?

We describe three patients with unilateral facial pain due to non-metastatic lung cancer and review 11 published cases. Pain, most frequently located on the right side and around the ear, as well as digital clubbing can be clues to an early diagnosis. Compression of the vagus nerve by the tumour or by mediastinal adenopathy is most likely responsible for the facial pain and could play a role in pulmonary osteoarthropathy.

Adult↗
PubMed1992

Exteroceptive suppression of temporalis muscle activity in various types of headache.

Exteroceptive suppression (ES) of temporalis muscle activity, particularly the multisynaptic ES2, has been reported to be significantly reduced in tension type headache, but not in migraine. We re-evaluated the methods of optimally analysing the single shock technique and its intra- and inter-individual variability in 26 normal subjects. These data were compared with the results in patients with migraine, post-lumbar puncture headache, headache due to meningitis, tension-type headaches in HIV infection and patients with symptomatic headache of various etiologies. ES2 was absent in about 50% of tension-type headache patients, but only in one normal subject. With the methods used here and when patients with absent ES2 were excluded, mean duration of ES2 was not significantly different between the various groups. It seems therefore necessary, in spite of increased discomfort for patients, to use complementary methods, such as averaging 16-32 responses and applying various stimulation sets, if one wants to increase the potency of temporalis ES2 as a diagnostic and pathophysiologic tool in headache.

Adult↗
PubMed1992

The recognition of hypothalamo-neurohypophysial functions by developing T cells.

Neuropeptide signals and specific neuropeptide receptors have been described in the thymus supporting the concept of a close dialogue between the neuroendocrine and the immune systems at the level of early T-cell differentiation. In this paper, we review recent data about neurohypophysial (NHP)-related peptides detected in the thymus from different species. We suggest that we are dealing in fact with other member(s) of the NHP hormone family, which seems to exert its activity locally through a novel model of cell-to-cell signaling, that of cryptocrine communication. This model involves exchange of signals between thymic epithelial cells and developing thymocytes. The NHP-related peptides have been shown to trigger thymocyte proliferation and could induce immune tolerance of this highly conserved neuroendocrine family.

Amino Acid Sequence↗
PubMed1992

[Electrophysiologic investigations in migraine].

This article is a critical review of standard electroencephalography (EEG), brain mapping, evoked potential, and electromyography (EMG) studies carried out in various forms of migraine during and between attacks. With the exception of contingent negative variation, the exteroceptive silent period of the temporalis muscle, and possibly fast activity in response to visual stimuli, which are useful for the differential diagnosis of functional headache, the main value of electrophysiologic studies is to provide insight into the pathophysiology of the disease. Results of the different methods consistently indicate that the brain of migraine patients is characterized by hypersensitivity to some forms of stimuli between attacks and by, often focal, hypoactivity during attacks.

Alpha Rhythm↗
PubMed1991

Grafts of syngenic cultured, adult dorsal root ganglion-derived Schwann cells to the injured spinal cord of adult rats: preliminary morphological studies.

Highly enriched cultures of Schwann cells were obtained from adult rat dorsal root ganglia and implanted (5 x 10(5) -9 x 10(5) cells) in the spinal cord of syngenic adult rats at the site of an acute compression lesion produced by a subdural inflatable microballoon. These autografts survived and invaded the host tissue, reducing central cavitation and astrocytic gliosis. They dramatically promoted ingrowth of axons, the majority of which appeared to come from the dorsal roots as judged by their neuropeptide content. Invasion of the transplants by descending, e.g. aminergic fibers, was negligible at survival times of up to 4 months. Nonetheless, autologous Schwann cells, which are readily available in the host, represent a promising material for grafts into the injured spinal cord.

Animals↗
PubMed1991

Monoclonal antibodies to oxytocin: production and characterization.

To induce a good immune response to oxytocin (OT) we developed a two-step technique to conjugate OT to thyroglobulin (TG) using glutaraldehyde. We obtained 30 hybridomas recognizing OT-ovalbumin conjugates and 16 stable lines. Three monoclonal antibodies were selected for further characterization. One of them (O13) was found very specific for OT using three different techniques (enzyme-linked immunosorbent assay, radioimmunoassay and immunohistochemistry); it is directed to the C-terminal tripeptide. The other two probably recognize tyrosine containing epitope(s) also shared by vasopressin and other related nonapeptides.

Animals↗
PubMed1991

Cephalic and extracephalic pressure pain thresholds in chronic tension-type headache.

Pressure pain thresholds were assessed with an algometer (Somedic Inc.), over the forehead, temple and suboccipital region as well as over the Achilles tendon. A group of 32 patients suffering from chronic tension-type headache was compared to 20 healthy controls and to 10 migraineurs without aura. Although individual values were widely scattered, pressure pain thresholds were on average significantly lower in chronic tension-type headache, not only at pericranial sites but also over the Achilles tendon. Only 50% of these patients had one or more pericranial thresholds 1.5 S.D. below the mean of controls. After muscular biofeedback therapy, all pain thresholds were on average increased. Along with results obtained previously, the present data support the hypothesis that diffuse disruption of central pain-modulating systems, possibly due to a modified limbic input to the brain-stem, is pivotal in the pathophysiology of chronic tension-type headache.

Adult↗
PubMed1991

Colocalization of immunoreactive oxytocin, vasopressin and interleukin-1 in human thymic epithelial neuroendocrine cells.

Monoclonal antibodies to oxytocin (OT) and vasopressin (VP) revealed some positively staining stromal cells in the subcapsular cortex and in the medulla of the human thymus. We further demonstrated that these cells are a subset of epithelial endocrine cells and also contain immunoreactive interleukin-1 together with the neuropeptides. In addition, the thymic cells stained by monoclonal antibodies directed to the cyclic part of oxytocin or vasopressin also contained some immunoreactive neurophysins. These data support the concept of intrathymic synthesis of neurohypophyseal-like peptides fitting the hypothalamic model. However, we observed that, contrary to the situation in the brain, OT- and VP-like peptides colocalized in the same thymic cells. Furthermore, one monoclonal antibody, specific for the tail part of oxytocin, did not label thymic cells. Therefore, thymic neuropeptide(s) could be related to, but distinct from, authentic OT and VP. These observations suggest some molecular differences between hypothalamic and thymic oxytocin biosynthetic pathways which need to be further investigated.

Antibodies, Monoclonal↗
PubMed1991

Exteroceptive silent period of temporalis muscle in menstrual headaches.

The second exteroceptive silent period (ES2) of temporalis muscle was recorded on days 1 and 15 of the menstrual cycle in 17 women, 9 of whom suffered regularly from tension-type headaches during menstruation. Mean duration of temporalis ES2 was significantly shorter on day 1 of the cycle than on day 15. This difference was due to a marked menstrual reduction of ES2 in the headache subgroup. A positive correlation was found between ES2 durations and oestradiol/progesterone ratios. We hypothesize that the variations of ES2 during the ovarian cycle result from the modulatory effects of oestrogens on descending aminergic pathways that control excitability of inhibitory brainstem interneurons mediating exteroceptive suppression of jaw-closing motoneurons.

Adult↗
PubMed1991

Blood magnesium levels in migraine.

Serum and erythrocyte magnesium levels were screened between attacks in patients with migraine without aura (n = 38) and with aura (n = 6), and for comparison in a group of patients suffering from chronic tension-type headache (n = 25) as well as a group of neurological, non-headache patients (n = 19). Serum magnesium levels were not significantly different between the four groups of patients. In contrast, magnesium in erythrocytes was on average significantly reduced in patients with migraine without aura compared to the other groups. It is hypothesized that this reduction might be due to an abnormal regulation of intracellular magnesium possibly reflecting at the periphery changes observed in the brain of migraineurs.

Adult↗
PubMed1991

Multiple clinical and paraclinical analyses of chronic tension-type headache associated or unassociated with disorder of pericranial muscles.

Thirty-two female patients fulfilling the diagnostic criteria of chronic tension-type headache underwent multiple clinical (severity index before and after biofeedback therapy; anxiety score) and paraclinical (pericranial EMG levels and pressure-pain thresholds, temporalis exteroceptive silent period) assessments. Twenty-three patients (72%) had at least one increased EMG level and/or at least one decreased pain threshold and qualified for the subgroup" associated with disorder of pericranial muscles" (code 2.2.1). Nine patients (28%) were within the normal range for both investigations and would have been classified in the subgroup "unassociated with such disorder" (code 2.2.2). No significant differences were found between these two groups of patients for headache severity, anxiety, response to biofeedback therapy or duration of temporalis second exteroceptive silent period. The various clinical and paraclinical parameters were not significantly correlated to each other. It is therefore suggested that the subdivision of chronic tension-type headache in two subgroups based on pericranial EMG levels and/or pain sensitivity might be artificial. Since both of the latter and temporalis silent periods vary independently, they appear complementary in the study of tension-type headache patients and probably represent peripheral abnormalities, which are induced to varying intensities by a common central nervous system dysfunction.

Adolescent↗