Morphine has a dual concentration-dependent effect on K+-evoked substance P release from rat peripheral airways

Our previous investigations of possible lung mechanisms underlying the effectiveness of nebulized morphine for the relief of dyspnoea, have shown a high density of non-conventional opioid binding sites in rat airways with similar binding characteristics (opioid alkaloid-sensitive, opioid peptide-insensitive) to that of putative mu(3)-opioid receptors on immune cells. To investigate whether these lung opioid binding sites are functional receptors, this study was designed to determine (using superfusion) whether morphine modulates the K+-evoked release of the pro-inflammatory neuropeptide, substance P (SP), from rat peripheral airways. Importantly, K+-evoked SP release was Ca2+-dependent, consistent with vesicular release. Submicromolar concentrations of morphine (1 and 200 nM) inhibited K+-evoked SP release from rat peripheral airways in a naloxone (1 mu M) reversible manner. By contrast, 1 mu M morphine enhanced K+-evoked SP release and this effect was not reversed by 1 mu M naloxone. However, 100 mu M naloxone not only antagonized the facilitatory effect of 1 mu M morphine on K+-evoked SP release from rat peripheral airways but it inhibited release to a similar extent as 200 nM morphine. It is possible that these latter effects are mediated by non-conventional opioid receptors located on mast cells, activation of which causes naloxone-reversible histamine release that in turn augments the release of SP from sensory nerve terminals in the peripheral airways. Clearly, further studies are required to investigate this possibility. (C) 1997 Academic Press Limited.

Enhanced downregulation of the p75 nerve growth factor receptor by cholesteryl and bis-cholesteryl antisense oligonucleotides

The effects of conjugating cholesterol to either or both ends of a phosphorothioate (PS) oligonucleotide were analyzed in terms of cellular uptake and antisense efficacy. The oligo sequence was directed against the p75 nerve growth factor receptor (p75), and was tested in differentiated PC12 cells, which express high levels of this protein. The addition of a single cholesteryl group to the 5'-end significantly increased cellular uptake and improved p75 mRNA downregulation compared with the unmodified PS oligo, However, only a minor degree of downregulation of p75 protein was obtained with 5' cholesteryl oligos, Three different linkers was used to attach the 5' cholesteryl group but were found not to have any impact on efficacy. Addition of a single cholesteryl group to the 3'-end led to greater p75 mRNA downregulation (31%) and p75 protein downregulation (28%) than occurred with the 5' cholesteryl oligos. The biggest improvement in antisense efficacy, both at the mRNA and protein levels, was obtained from the conjugation of cholesterol to both ends of the oligo. One of the bis-cholesteryl oligos was nearly as effective as cycloheximide at decreasing synthesis of p75, The bis-cholesteryl oligos also displayed significant efficacy at 1 mu M, whereas the other oligos required 5 mu M to be effective. The enhanced efficacy of bis-cholesteryl oligos is likely to be due to a combination of enhanced cellular uptake and resistance to both 5' and 3' exonucleases.

Molecular development of the olfactory nerve pathway

There are, at least, two major questions concerning the molecular development of the olfactory nerve pathway. First, what are the molecular cues responsible for guiding axons from the nasal cavity to the olfactory bulb? Second, what is the molecular basis of axon targeting to specific glomeruli once axons reach the olfactory bulb? Studies in the primary olfactory pathway have focused on the role of the extracellular matrix and ensheathing cells in establishing an initial substrate for growth of pioneer axons between the periphery and brain. The primary axons also express a multitude of cell adhesion molecules that regulate fasciculation of axons and hence may play a role in fascicle formation in the olfactory nerve. Although the olfactory neuroepithelium principally consists of a morphologically homogeneous class of primary olfactory neurons, there are numerous subpopulations of olfactory neurons expressing chemically distinct phenotypes. In particular, numerous subpopulations have been characterized by expression of unique carbohydrate residues and olfactory receptor proteins. Some of these molecules have recently been implicated in axon guidance and targeting to specific glomeruli.

Expression of galectin-1 in the olfactory nerve pathway of rat

The olfactory neuroepithelium is characterised by the mosaic distribution of primary olfactory neurons that express different odorant receptors and cell surface glycoconjugates. Carbohydrates are believed to form a glycocode that mediates sorting out and fasciculation of primary olfactory axons through interactions with carbohydrate-binding proteins such as galectin-1. In the present study, we describe in detail the expression pattern of galectin-1 in the developing and adult rat olfactory system. We demonstrate that galectin-1 is expressed by olfactory ensheathing cells both in olfactory nerve and within the nerve fibre layer of the olfactory bulb of the embryonic and adult rat. In the adult rat, galectin-1 was preferentially expressed by olfactory ensheathing cells in the nerve fibre layer of the ventromedial and lateral surfaces of the olfactory bulb. Galectin-1 was also expressed by subsets of periglomerular cells and granule cells, particularly in the ventromedial region of the olfactory bulb. In adult rat, the galectin-1 ligand, N-acetyl-lactosamine, was expressed by primary olfactory axons that terminated in glomeruli present in the ventromedial and lateral olfactory bulb. These results suggest that expression of galectin-1 may provide a mechanism for the sorting of subpopulations of axons in the nerve fibre layer of the olfactory bulb during development as well as play a role in the postnatal maintenance of specific glomerular connections. (C) 1999 Elsevier Science B.V. All rights reserved.

Expression of EphA5 during development of the olfactory nerve pathway in rat

The olfactory neuroepithelium is a highly plastic region of the nervous system that undergoes continual turnover of primary olfactory neurons throughout life. The mechanisms responsible for persistent growth and guidance of primary olfactory axons along the olfactory nerve are unknown. In the present study, we used antibodies against the Eph-related receptor, EphA5, to localise EphA5, and recombinant EDhA5-IgG fusion protein to localise its ligands. We found that although both EphA5 and its ligands were both expressed by primary olfactory neurons within the embryonic olfactory nerve pathway, there was no graded or complementary expression pattern. In contrast, the expression patterns altered postnatally such that primary olfactory neurons expressed the ligands, whereas the second-order olfactory neurons, the mitral cells, expressed EphA5. The role of EphA5 was analysed by blocking EphA5-ligand interactions in explant cultures of olfactory neuroepithelium using anti-EphA5 antibodies and recombinant EphA5. These perturbations reduced neurite outgrowth from explant cultures and suggest that intrafascicular axon repulsion may serve to limit adhesion and optimise conditions for axon growth. (C) 2000 Wiley-Liss, Inc.

Exposure of rats to a high but not low dose of ethanol during early postnatal life increases the rate of loss of optic nerve axons and decreases the rate of myelination

Visual system abnormalities are commonly encountered in the fetal alcohol syndrome although the level of exposure at which they become manifest is uncertain. In this study we have examined the effects of either low (ETLD) or high dose (ETHD) ethanol, given between postnatal days 4-9, on the axons of the rat optic nerve. Rats were exposed to ethanol vapour in a special chamber for a period of 3 h per day during the treatment period. The blood alcohol concentration in the ETLD animals averaged similar to 171 mg/dl and in the ETHD animals similar to 430 mg/dl at the end of the treatment on any given day. Groups of 10 and 30-d-old mother-reared control (MRC), separation control (SC), ETLD and ETHD rats were anaesthetised with an intraperitoneal injection or ketamine and xylazine, and killed by intracardiac perfusion with phosphate-buffered glutaraldehyde. In the 10-d-old rat optic nerves there was a total of similar to 145000-165000 axons in MRC, SC and ETLD animals. About 4 % of these fibres were myelinated. The differences between these groups were not statistically significant. However, the 10-d-old ETHD animals had only about 75000 optic nerve axone (P < 0.05) of which about 2.8 % were myelinated. By 30 d of age there was a total of between 75000 90000 optic nerve axons, irrespective of the group examined. The proportion of axons which were myelinated at this age was still significantly lower (P < 0.001) in the ETHD animals (similar to 77 %) than in the other groups (about 98 %). It is concluded that the normal stages of development and maturation of the rat optic nerve axons, as assessed in this study, can be severely compromised by exposure to a relatively high (but not low) dose of ethanol between postnatal d 4 and 9.

In vivo measurement of the effect of intra-abdominal pressure on the human spine

In humans, intra-abdominal pressure (IAP) is elevated during many everyday activities. This experiment aimed to investigate the extent to which increased IAP-without concurrent activity of the abdominal or back extensor muscles-produces an extensor torque. With subjects positioned in side lying on a swivel table with its axis at L3, moments about this vertebral level were measured when IAP was transiently increased by electrical stimulation of the diaphragm via the phrenic nerve. There was no electromyographic activity in abdominal and back extensor muscles. When IAP was increased artificially to similar to 15% of the maximum IAP amplitude that could be generated voluntarily with the trunk positioned in flexion, a trunk extensor moment (similar to6 Nm) was recorded. The size of the effect was proportional to the increase in pressure. The extensor moment was consistent with that predicted from a model based on measurements of abdominal cross-sectional area and IAP moment arm. When IAP was momentarily increased while the trunk was flexed passively at a constant velocity, the external torque required to maintain the velocity was increased. These results provide the first in vivo data of the amplitude of extensor moment that is produced by increased IAP. Although the net effect of this extensor torque in functional tasks would be dependent on the muscles used to increase the IAP and their associated flexion torque, the data do provide evidence that IAP contributes, at least in part, to spinal stability. (C) 2001 Elsevier Science Ltd. All rights reserved.

CD40 ligation conditions dendritic cell antigen-presenting function through sustained activation of NF-kappa B

An understanding of the biochemical control of dendritic cell (DC) differentiation/activation is essential for improving T cell immunity by various immunotherapeutic approaches, including DC immunization. Ligation of CD40 enhances DC function, including conditioning for CTL priming. NF-kappaB, and particularly RelB, is an essential control pathway for myeloid DC differentiation. Furthermore, RelB regulates B cell Ag-presenting function. We hypothesized that CD40 ligand (CD40L) and TNF-alpha, which differ in their capacity to condition DC, would also differ in their capacity to activate NF-kappaB. DC differentiated for 2 days from monocytes in the presence of GM-CSF and IL-4 were used as a model, as NF-kappaB activity was constitutively low. The capacity of DC to activate T cells following CD40L treatment was enhanced compared with TNF-alpha treatment, and this was NF-kappaB dependent. Whereas RelB/p50 translocation induced by TNF-alpha was attenuated after 6 h, RelB/p50 nuclear translocation induced by CD40L was sustained for at least 24 h. The mechanism of this difference related to enhanced degradation of IkappaBalpha following CD40L stimulation. However, NF-kappaB activation induced by TNF-alpha could be sustained by blocking autocrine IL-10. These data indicate that NF-kappaB activation is essential for T cell activation by DC, and that this function is enhanced if DC NF-kappaB activation is prolonged. Because IL-10 moderates DC NF-kappaB activation by TNF-alpha, sustained NF-kappaB activation can be achieved by blocking IL-10 in the presence of stimuli that induce TNF-alpha.

Insights into the organization of dorsal spinal cord pathways from an evolutionarily conserved raldh2 intronic enhancer

Comparative studies of the tetrapod raldh2 (aldh1a2) gene, which encodes a retinoic acid (RA) synthesis enzyme, have led to the identification of a dorsal spinal cord enhancer. Enhancer activity is directed dorsally to the roof plate and dorsal-most (dl1) interneurons through predicted Tcf- and Cdx-homeodomain binding sites and is repressed ventrally via predicted Tgif homeobox and ventral Lim-homeodomain binding sites. Raldh2 and Math1/Cath1 expression in mouse and chicken highlights a novel, transient, endogenous Raldh2 expression domain in dl1 interneurons, which give rise to ascending circuits and intraspinal commissural interneurons, suggesting roles for RA in the ontogeny of spinocerebellar and intraspinal proprioceptive circuits. Consistent with expression of raldh2 in the dorsal interneurons of tetrapods, we also found that raldh2 is expressed in dorsal interneurons throughout the agnathan spinal cord, suggesting ancestral roles for RA signaling in the ontogenesis of intraspinal proprioception.

Bile duct ligation in neonatal rats: Is it a valid experimental model for biliary atresia studies?

BA is the most important disease requiring liver transplantation in children. Common BDL in rats is a classic experimental model to study biliary obstruction. The response of the neonatal animal to BDL has yet to be completely understood and few reports have focused on the behavioral differences of the liver between neonatal and adult animals. Ninety newborn Wistar rats aged six days, weighing 8.0-13.9 g, and 90 adult Wistar rats weighing 199.7-357.0 g, were submitted to BDL. After surgery, they were randomly divided and killed on the 3rd, 5th, 7th, 14th, 21st and 28th day post-BDL. Hepatic biopsies were obtained and the following were measured: (i) semiquantification of the bile ductule proliferation and inflammatory infiltrate by HE stain, (ii) quanti. cation of portal and periportal fibrosis with the Sirius-red stain. Although the initial response of ductule proliferation and inflammatory infiltrate were less intense in the newborn animal, the portal and periportal fibrosis were higher when compared with adult animals (p < 0.0491). These findings may contribute to the understanding of the pathophysiology of BA.

Hemihypoglossal-facial neurorrhaphy after mastoid dissection of the facial nerve: Results in 24 patients and comparison with the classic technique

OBJECTIVE: Hypoglossal-facial neurorrhaphy has been widely used for reanimation of paralyzed facial muscles after irreversible proximal injury of the facial nerve. However, complete section of the hypoglossal nerve occasionally results in hemiglossal dysfunction and interferes with swallowing and speech. To reduce this morbidity, a modified technique with partial section of the hypoglossal nerve after mastoid dissection of the facial nerve (HFM) has been used. We report our experience with the HFM technique, retrospectively comparing the outcome with results of the classic hypoglossal-facial neurorrhaphy. METHODS: A retrospective review was performed in 36 patients who underwent hypoglossal-facial neurorrhaphy with the classic (n = 12) or variant technique (n = 24) between 2000 and 2006. Facial Outcome was evaluated with the House-Brackmann grading system, and tongue function was evaluated with a new scale proposed to quantify Postoperative tongue alteration. The results were compared, and age and time between nerve injury and surgery were correlated with the outcome. RESULTS: There was no significant difference between the two techniques concerning facial reanimation. A worse outcome of tongue function, however, was associated with the classic technique (Mann-Whitney U test; P < 0.05). When HFM was used, significant correlations defined by the Spearman test were identified between preoperative delay (p = 0.59; P = 0.002) or age (p = 0.42; P = 0.031) and results of facial reanimation evaluated with the House-Brackmann grading system. CONCLUSION: HFM is as effective as classic hypoglossal-facial neurorrhaphy for facial reanimation, and it has a much lower morbidity related to tongue function. Better results are obtained in younger patients and with a shorter interval between facial nerve injury and surgery.

Idiopathic spinal epidural hematoma in patients with sudden paraplegia: A case report

Introduction. Spontaneous spinal epidural hematoma (SEH) represents 0.3-0.9% of spinal epidural space-occupying lesions, and most surgeons advocate aggressive and early surgical intervention. In. this paper we describe a patient with SEH with sudden paraplegia. Case report. This 30-year-old man had experienced one prior episode of sudden dorsal pain two days before the current admission and while he waited medical attendance, his legs suddenly became weak, and immediately afterwards, he became completely paraplegic in minutes. The patient had complete paraplegia, analgesia below the T4 level and urinary retention. He had no anticoagulant agent and no coagulopathic disease. He was submitted to computerized tomography that demonstrated a dorsally located epidural hematoma extending from the T3 to the T6 level with spinal cord compression. A laminectomy from T3 to T7 was performed four hours after the onset of the symptom. In postoperative time the patient presented the partial sensorial recovery and motor force grade II. The patient was directed to a neurorehabilitation program and in the last medical evaluation he presented recovery for motor grade III-IV without pain. Conclusion. The SHE is rare, with severe neurological consequences for patients and early surgical treatment persist as essential for motor recovery.

Correlation between macular and retinal nerve fibre layer Fourier-domain OCT measurements and visual field loss in chiasmal compression

Purpose The aim of this study was to test the correlation between Fourier-domain (FD) optical coherence tomography (OCT) macular and retinal nerve fibre layer (RNFL) thickness and visual field (VF) loss on standard automated perimetry (SAP) in chiasmal compression. Methods A total of 35 eyes with permanent temporal VF defects and 35 controls underwent SAP and FD-OCT (3D OCT-1000; Topcon Corp.) examinations. Macular thickness measurements were averaged for the central area and for each quadrant and half of that area, whereas RNFL thickness was determined for six sectors around the optic disc. VF loss was estimated in six sectors of the VF and in the central 16 test points in the VF. The correlation between VF loss and OCT measurements was tested with Spearman`s correlation coefficients and with linear regression analysis. Results Macular and RNFL thickness parameters correlated strongly with SAP VF loss. Correlations were generally stronger between VF loss and quadrantic or hemianopic macular thickness than with sectoral RNFL thickness. For the macular parameters, we observed the strongest correlation between macular thickness in the inferonasal quadrant and VF loss in the superior temporal central quadrant (rho=0.78; P<0.001) whereas for the RNFL parameters the strongest correlation was observed between the superonasal optic disc sector and the central temporal VF defect (rho=0.60; P<0.001).

Neck Nerve Trunks Schwannomas: Clinical Features and Postoperative Neurologic Outcome

Objectives/Hypothesis: To analyze clinical and epidemiological features of neck nerve schwannomas, with emphasis on the neurologic outcome after surgical excision sparing as much of nerve fibers as possible with enucleation technique. Study Design: Retrospective study. Methods: Review of medical records from 1987 to 2006 of patients with neck nerve schwannomas, treated in a single institution. Results: Twenty-two patients were identified. Gender distribution was equal and age ranged from 15 to 61 years (mean: 38.6 years). Seven vagal, four brachial plexus, four sympathetic trunk, three cervical plexus, and two lesions on other sites could be identified. Most common symptom was neck mass. Local or irradiated pain also occurred in five cases. Median growing rate of tumors was 3 mm per year. Nerve paralysis was noted twice (a vagal schwannoma and a hypoglossal paralysis compressed by a vagal schwannoma). Different techniques were employed, and seven out of nine patients kept their nerve function (78%) after enucleation. No recurrence was observed in follow-up. Conclusions: Schwannomas should be treated surgically because of its growing potential, leading to local and neural compression symptoms. When possible, enucleation, which was employed in 10 patients of this series, is the recommended surgical option, allowing neural function preservation or restoration in most instances. This is especially important in the head and neck, where denervation may have a significant impact on the quality of life.