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Biomedical subjects

N Canal

Publications and source records attributed to N Canal.

At least 19 recordsLinked to original sources
PubMed2001

Human IgM anti-GM1 autoantibodies modulate intracellular calcium homeostasis in neuroblastoma cells.

Increased titers of IgM anti-GM1 antibodies are present in some patients with Lower Motor Neuron Disease (LMND) or Motor Neuropathy (MN), but their pathogenic role and the mechanism of action are unclear. Previous studies have shown that the B subunit of Cholera Toxin (CT), which binds and crosslinks ganglioside GM1, modulate intracellular calcium in murine neuroblastoma cells via the activation of L-type voltage-dependent calcium channels (VGCC). Therefore, using a fluorimetric approach, we have examined the hypothesis that the pentameric IgM anti-GM1 antibodies, could similarly alter calcium concentration in N18 neuroblastoma cells. Sera with human IgM anti-GM1 antibodies were obtained from 5 patients with LMND and 2 patients with MN. Human IgG anti-GM1, IgM anti-Myelin Associated Glycoprotein (MAG), IgM anti-sulfatide antibodies and lectin peanut agglutinin (PNA), that recognizes specifically the Gal(betal-3)GalNAc epitope, were used as control sera. Direct application of either human IgM anti-GM1 antibodies or the B subunit of CT to N18 neuroblastoma cells induced a sustained influx of manganese ions, as indicated by a quench of the intracellular fura-2 fluorescence. Furthermore, the dihydropyridine L-type channel antagonists completely inhibited the manganese influx, suggesting that it is due to activation of an L-type VGCC. The magnitude of the influx was correlated with antibody titers. None of human IgG anti-GM1, IgM anti-MAG, IgM anti-sulfatide antibodies or PNA induce an ion influx, pointing to the selective participation of the pentameric IgM isotype of anti-GM1 in the modulation of L-type calcium channels opening. Given that L-type calcium channels are present on motor neurons, the modulation of L-type calcium channels by IgM GM1 antisera may have important implications in diseases such as LMND and MN.

Adult↗
PubMed2000

Association study of a new polymorphism in the PECAM-1 gene in multiple sclerosis.

Genetic polymorphisms of immunorelevant genes may modulate occurrence or clinical features of multifactorial diseases. PECAM-1 is an adhesion molecule crucial for transmigration of cells from blood to tissues, but its genetic contribution to multifactorial diseases has never been investigated. We have identified and characterized a tetranucleotide repeat polymorphism within the third intron of PECAM-1. In a cohort of healthy controls (HC), we found 10 alleles. An assessment of the association of this polymorphism with multiple sclerosis (MS) showed similar allele and genotype frequencies in HC and MS patients as well as in MS patients differing for the gravity of their disease course. We conclude that although potentially able to affect organ-specific autoimmune diseases, this new PECAM-1 polymorphism, does not seem to contribute to the genetic background of MS.

Adult↗
PubMed2000

Association of early-onset Alzheimer's disease with an interleukin-1alpha gene polymorphism.

Overexpression of the pluripotent cytokine interleukin-1 (IL-1) by microglial cells correlates with formation of neuritic beta-amyloid plaques in Alzheimer's disease (AD). We evaluated polymorphisms in the genes coding for the IL-1alpha, IL-1beta, and IL-1 receptor antagonist cytokines, and tested their association with the occurrence and age at onset of sporadic AD. We found a strong association between the IL-1A T/T genotype and AD onset before 65 years of age (odds ratio, 4.86), with carriers of this genotype showing an onset of disease 9 years earlier than IL-1A C/C carriers. A weaker association with the age at onset was also shown for the IL-1B and IL-1RN genes. These data suggest either a direct effect of the IL-1 gene family, mainly IL-1A, on the clinical onset of AD, or a linkage dysequilibrium with an unknown locus relevant to AD on chromosome 2.

Adult↗
PubMed2000

Induction of IL-1 receptor antagonist by interferon beta: implication for the treatment of multiple sclerosis.

IFNbeta has been the first drug approved for the treatment of multiple sclerosis patients, but we still lack a full understanding of the mechanisms underlying its clinical effects and the great variability of its therapeutic efficacy among different patients. Serum levels of the anti-inflammatory cytokine IL-1 receptor antagonist increase after IFNbeta administration in MS patients. We now report that IFNbeta induced IL-1ra mRNA and mature protein in three myelomonocytic cell lines. The induction of IL-1ra was already visible after 2 h of stimulation and persisted at least for 24 h. The amounts of induced IL-1ra were equal or higher than those obtained using other IL-1ra stimuli (LPS, IL-1beta, IFNgamma, IL-4, dexamethasone). This prolonged and quantitatively elevated induction of IL-1ra may contribute to the anti-inflammatory effect of IFNbeta and partially account for the reduction of exacerbation rate shown in most IFNbeta-treated MS patients.

Adjuvants, Immunologic↗
PubMed1999

Relevance of interleukin 1 receptor antagonist intron 2 polymorphism in Italian MS patients.

The A1/A1 genotype of the anti-inflammatory cytokine interleukin 1 receptor antagonist (IL-1Ra) polymorphism was more frequent in 339 Italian MS patients than in healthy controls (HCs) (odds ratio = 1.83). A more aggressive disease course was also associated with A1+ genotypes and might reflect the reduced ability of mononuclear cell cultures of A1+ HCs to produce IL-1Ra. We conclude that an IL-1Ra gene polymorphism is associated with occurrence of disease and clinical course variability in Italian MS patients.

Adult↗
PubMed1999

Docetaxel neuropathy: a distal axonopathy.

Docetaxel has been implicated as a causative agent in peripheral neuropathy, but pathological changes in peripheral nerve have not been described. During docetaxel treatment a 54-year-old man developed a sensorimotor polyneuropathy when the overall docetaxel dosage was 540 mg/m(2). Neurophysiological investigation revealed a sensorimotor axonal neuropathy. Fascicular sural nerve biopsy showed an axonal neuropathy with a preferentially loss of large myelinated fibers. There was evidence of considerable fiber regeneration. Sensory and motor symptoms progressively improved after docetaxel withdrawal.

Antineoplastic Agents, Phytogenic↗
PubMed1999

Long-term follow-up of isolated optic neuritis: the risk of developing multiple sclerosis, its outcome, and the prognostic role of paraclinical tests.

We evaluated the risk of developing clinically definite multiple sclerosis (CDMS) after an acute attack of isolated optic neuritis (ON) in 112 patients, in relation to demographic and paraclinical findings. Patients were examined by brain MRI, CSF analysis, and multiple evoked potentials (EPs); 10 were lost to follow-up, and the other 102 were enrolled in a prospective study (follow-up duration 6. 3 +/- 2.2 years). Of these, 37 (36.3%) developed CDMS after a mean interval of 2.3 +/- 1.6 years. The risk of developing CDMS was 13% after 2 years, 30% after 4, 37% after 6, and 42% after 8 and 10 years. Gender, age, and season of ON onset did not affect the risk. MS occurred in 37 of 71 patients (52.1%) with one MRI lesion or more; no patient with a normal MRI developed the disease. MS developed more frequently in patients with intrathecal IgG synthesis than in those without (43% vs. 28%), but the difference was not statistically significant. Multiple EPs showed a slight predictive value only including somatosensory EPs of the lower limb. Multiple sclerosis was mild in most cases (EDSS 2.2 +/- 1.9). The EDSS was less than 4 in 32 cases (86%), between 4 and 6 in 2 (5%), higher than 6.5 in 3 (8%).

Adult↗
PubMed1999

Adhesion of mononuclear cells from multiple sclerosis patients to cerebral vessels in cryostat sections of normal human brain.

Leukocyte extravasation across the blood-brain barrier is a critical event in the pathogenesis of multiple sclerosis (MS). This complex multistep process includes the adhesion of leukocytes to the endothelial cells of the central nervous system microvasculature. To investigate this phenomenon in MS, we developed a modified version of the frozen-section assay. Peripheral blood mononuclear cells (PBM) from 26 MS patients, 26 healthy controls and 10 patients with other inflammatory non- neurological diseases (OIND) were co-incubated with cryostat sections of normal brain white matter, immunohistochemically labelled with anti-CD45 antibody and counterstained with Giemsa stain. CD45-positive PBM adherent to transected microvasculature were counted with an automated image analyzer. MS patients showed an increased number of vessel-bound PBM (48.8 +/- 36.4) with respect to healthy controls (27.4 +/- 20.7, P = 0.01) and OIND patients (22.6 +/- 7.8, P = 0.01). Significant differences were also obtained counting the number of vessel-bound PBM as a percent of total vascular cells between MS patients (12.7 +/- 7.2%) and healthy controls (6.9 +/- 5.4%, P = 0.002) or OIND patients (7.4 +/- 4.4%, P = 0.03). We confirm that PBM from MS patients show an increased potential of binding to cerebral vessels. The frozen-section assay provides a unique tool to study in situ the molecular interactions of leukocytes with brain vascular structures.

Adult↗
PubMed1999

Laminin receptor alpha6beta4 integrin is highly expressed in ENU-induced glioma in rat.

Laminins and their receptors influence neoplastic growth and invasiveness. We recently reported the abnormal expression of a laminin receptor, alpha6beta4 integrin, in human astrocytomas. To further investigate the role of alpha6beta4 in gliomas, we produced an experimental model of glioma in rat by transplacental ethylnitrosourea (ENU) administration. This animal model allowed us to study the timing of alpha6beta4 expression during tumor development and the topography of expression in the tumor and the surrounding tissue. Immunohistochemistry, in situ hybridization, and immunoprecipitation studies demonstrated that alpha6beta4 heterodimer forms in experimental gliomas, and confirmed that alpha6beta4 is expressed diffusely in neoplastic cells and reactive astrocytes, but not in normal glia surrounding the tumors. Interestingly, alpha6beta4 was expressed from the early phases of tumor development, and more highly expressed by cells in the proliferative centers of the tumors. Both neoplastic cells and reactive astrocytes also expressed the glial growth factor (neuregulin) receptors, Erb-B2 and Erb-B3. Finally, alpha6beta4 expression was reduced in a subset of tumor blood vessels. Thus, this study suggests a potential role for alpha6beta4 in the pathogenesis of gliomas. Furthermore, this is the first description of altered integrin expression in experimental gliomas; transplacental ENU-induced gliomas in rat will provide a useful model to study the role of altered adhesion in the pathogenesis of human gliomas.

Animals↗
PubMed1997

Motor nerve biopsy studies in motor neuropathy and motor neuron disease.

The clinical presentation of motor neuropathy often resembles that of motor neuron disease, sometimes leading to an erroneous diagnosis. Moreover, the underlying pathological process in motor neuropathy has been rarely investigated and there are no systematic studies of the affected motor nerves. We describe a new motor nerve biopsy procedure, performed in 15 patients: 6 with motor neuropathy and 9 with motor neuron disease. The motor branch from the anterior division of the obturator nerve to the gracilis muscle in the thigh was biopsied. In both groups of patients the motor nerves exhibited depletion of myelinated nerve fibers. In motor neuropathy there was a significantly higher density of regenerative clusters of small myelinated fibers in comparison to motor nerves from patients with motor neuron disease. In addition, in 3 patients with motor neuropathy there was evidence for demyelination with thinly myelinated axons and small onion bulb formations. These pathological studies of motor nerve biopsies can help to differentiate motor neuropathy from motor neuron disease.

Adult↗
PubMed1997

Axonal neuropathy associated with interferon-alpha treatment for hepatitis C: HLA-DR immunoreactivity in Schwann cells.

A 44-year-old man developed a peripheral neuropathy during treatment with interferon-alpha for chronic hepatitis C. The onset was insidious, beginning symmetrically in the hands with paresthesia. Neurophysiological investigation revealed a predominantly sensory axonal neuropathy. A sural nerve biopsy confirmed primary axonal damage. Immunofluorescence studies showed increased expression of HLA-DR molecules prevalently on Schwann cells of non-myelin-forming type.

Adult↗
PubMed1997

Circulating fragments of myelin-associated alpha 6 beta 4 integrin in Guillain-Barré syndrome.

Guillain-Barré-Strohl syndrome (GBS) is an acute peripheral neuropathy causing reversible myelin damage. alpha 6 beta 4 is a laminin receptor of Schwann cells and myelin. Along with myelin breakdown, alpha 6 beta 4 immunoreactivity might be detected in patients' sera and provide a marker for monitoring GBS course. MAbs to beta 4 and alpha 6 were used in an ELISA test to detect protein in GBS serum samples as in normal individuals. In 66% GBS patients, alpha 6 beta 4 immunoreactivity was detected while controls were negative. The level of beta 4 was followed in different patients and found to fluctuate, always being positive in at least one sample. Treatment lowered immunoreactivity in two beta 4-positive GBS sera. Then, circulating alpha 6 beta 4 fragments represent a novel marker of extensive peripheral myelin damage and may be used to validate clinical diagnosis of GBS, evaluate its course and activity.

Acute Disease↗
PubMed1997

Headache in a population-based elderly cohort. An ancillary study to the Italian Longitudinal Study of Aging (ILSA).

The aims of this ancillary study to the Italian Longitudinal Study of Aging were: (1) to provide reliable prevalence data on headache in an elderly population, (2) to classify the subtypes of headache according to International Headache Society criteria, and (3) to identify possible risk factors and associated pathologies in the elderly. A total of 312 subjects were examined, 148 women and 164 men, with a mean age of 73 years (SD 5.5). For 236 subjects (75.7%), 141 men (85.9%) and 95 women (64.2%), headache had never been a problem; 57 subjects (18.3%), 21 men (12.8%) and 36 women (24.3%), reported troublesome headache only in the past. Nineteen subjects (6%), 6 men (3.6%) and 13 women (8.8%), reported current headache: in this group tension-type headache was the most prevalent, accounting for 2.6%; secondary headaches ranked second, accounting for 2.2%; and only 1% had current migraine. Our data indicate female sex and younger age as risk factors for headache, and associate migraine and secondary headaches with hypertension, tension-type headaches and secondary headaches with diabetes, and tension-type headaches with myocardial ischemia.

Age Factors↗
PubMed1997

Atypical hereditary neuropathy with liability to pressure palsies (HNPP): the value of direct DNA diagnosis.

We report two patients with suspected hereditary liability to pressure palsies. Neurophysiological studies showed a mixed axonal-demyelinating sensory-motor polyneuropathy with focal slowing of conduction velocities at the common sites of entrapment. Morphological studies on sural nerve biopsy from the proband showed active axonal regeneration without typical tomacula. Molecular analysis confirmed the presence of a deletion of chromosome 17p11.2 in both patients. Our observation confirms the heterogeneity of hereditary liability to pressure palsies and the relevance of DNA testing for the diagnosis of this hereditary neuropathy.

Adolescent↗
PubMed1997

Autoimmunity and diabetic neuropathy.

Autoimmunity has been implicated in the pathogenesis of diabetic neuropathy. A number of putative target antigens have been investigated in the attempt to find a relationship between the presence of autoantibodies and the presence of neuropathy. Attention has been given to antibodies against nerve growth factor, adrenal medulla, sympathetic and parasympathetic structures, glutamic acid decarboxylase and phospholipids. Data in the literature do not support a clear-cut difference in frequency of positivity or titres between patients with or without diabetic neuropathy. Moreover, it is not clear whether autoantibodies to the above-mentioned antigens, whenever present, play a role in causing nerve damage or if they simply reflect the presence of nerve damage. Longitudinal studies are needed to clarify some conflicting data in the literature.

Adrenal Medulla↗