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Biomedical subjects

N Canal

Publications and source records attributed to N Canal.

At least 91 records · Page 5Linked to original sources
PubMed1990

Prognostic value of the nervous system involvement in HIV patients.

About 30-40% of AIDS patients present CNS and/or PNS involvement, due to direct action of HIV virus or opportunistic infections. Nervous system involvement in the HIV correlated syndromes is not a rare occurrence; nevertheless no studies about prognosis of AIDS related syndromes have been published yet. We tested 38 HIV positive patients for the assessment of neurological complications by means of clinical and instrumental evaluations: multimodal evoked potentials, EMG/ENG studies, nerve and muscle biopsy. At the baseline evaluation, 26/38 patients had neurological complications: 14 of CNS, 9 of PNS, 3 of both CNS and PNS. At follow-up, 16/37 patients had developed AIDS and 10/16 patients with AIDS died. Of these 16 patients, 14 had clinical and neurophysiological alterations at the baseline evaluation. Our results suggest that the presence of clinical and/or neurophysiological nervous system involvement in patients with HIV-related syndromes constitutes a negative prognostic factor for developing AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Specificity of calcium channel autoantibodies in Lambert-Eaton myasthenic syndrome.

Autoantibodies that interfere with neurotransmitter release by affecting the function of voltage-operated calcium channels (VOCCs) have been found in patients with Lambert-Eaton myasthenic syndrome (LES). To find out the nature of the antigen to which these autoantibodies bind, tests were done with omega-conotoxin, which blocks some types of VOCCs. LES antibodies were able to immunoprecipitate VOCCs prepared from the human neuronal cell line IMR32 which were pre-labelled with the specific VOCC ligand omega-conotoxin. LES autoantibodies are also able to specifically down-regulate the expression of VOCCs in IMR32 cells. A new radioimmunoassay for the quantitative detection of LES antibodies was developed and found to be of value in distinguishing LES patients from patients with myasthenia gravis and some other neurological disorders.

Autoantibodies↗
PubMed1989

Cortical pathophysiology and clinical neurologic abnormalities in acute cerebral ischemia. A serial study with single photon emission computed tomography.

We studied brain cortical radioactive tracer activity in a consecutive series of nine patients with acute hemispheric ischemic stroke at their first cerebral ischemic stroke at their first cerebral ischemic episode. Results from N,N,N'-trimethyl-N'- (2-hydroxy-3-methyl-5-[123-I]-iodobenzyl)-1,3 propanediamine-2HCl (four patients) and technetium Tc 99m hexamethylpropyleneamine oxime (five patients) single photon emission computed tomographic studies were compared with x-ray computed tomography (CT) and clinical findings within the first 48 hours, on day 10, and on day 30 after the clinical ictus. Cortical hypoactivity agreeing with the clinical findings was found on all initial scans but not in the follow-up studies. Cortical activity on the affected side in patients with stroke was significantly lower when compared with cortical activity in sex- and age-matched controls (n = 21). Computed tomography (with contrast) was less sensitive in detecting the ischemic lesions. These studies demonstrate that in the acute phase of stroke there is a single photon emission computed tomographic cortical disturbance that agrees with clinical findings, even when computed tomography scan infarction is limited to subcortical structures.

Adult↗
PubMed1989

Correlation between multimodal evoked potentials and magnetic resonance imaging in multiple sclerosis.

Sixty multiple sclerosis (MS) patients (33 definite, 13 probale and 14 suspected were investigated by computed tomography (CT), magnetic resonance imaging (MRI), multimodality evoked potentials (EPs) and cerebrospinal fluid (CSF) electrophoresis. MRI abnormalities were found in 50 cases, while at least one abnormal evoked potential was detected in each of 52 cases. Brain-stem auditory evoked potentials were more sensitive than MRI for the detection of brain-stem involvement. All the patients with oligoclonal bands had abnormal MRI and none of the patients with normal MRI had oligoclonal bands in the CSF. The number and the extent of MRI lesions were significantly correlated with the duration of disease and with the degree of disability. Our observations stress the importance of the combined use of MRI and EPs in detecting silent CNS lesions in MS patients.

Adult↗
PubMed1989

Polyamine biosynthetic decarboxylases in muscles of rats with different experimental myopathies.

The activities of the two polyamine biosynthetic decarboxylases (PBD), L-ornithine decarboxylase (ODC) and S-adenosyl-L-methionine decarboxylase (SAMD), have been measured in quadriceps femoris of rats killed at different times after the induction of calciphylaxis- or serotonin(5-HT)-induced myopathy. Decreases in both PBD levels were observed at early times after both myotoxic treatments. Subsequent progressive increases in both enzyme levels were observed to nearly control values by 4 days after 5-HT administration. In the 5-HT-treated rats, the effects on the myocardial PBD activities were different from those in skeletal muscle, with no effect on ODC but much on SAMD, when rats were killed shortly after 5-HT injection. These results demonstrate that the time-course of the changes in PBD activities in quadriceps femoris mirrors quite well the successive occurrence of degenerative and regenerative processes during the calciphylaxis-induced myopathy and the 5-HT-induced myopathy; it is 5-HT that is mainly responsible for the decreases in PBD levels observed in both experimental myopathies, since dihydrotachysterol alone was without any effect on PBD activity levels and 5-HT alone was effective; myocardial ODC reacts more slowly to 5-HT than quadriceps femoris ODC.

Adenosylmethionine Decarboxylase↗
PubMed1989

Neuron-binding antibodies in Alzheimer's disease and Down's syndrome.

We used an indirect immunoperoxidase technique (Avidin-Biotin system) to study the sera of patients with "clinically probable" Alzheimer's disease (AD) and with Down's Syndrome (DS), compared with age-matched controls. Diluted sera were incubated with paraffin sections of hippocampus, frontal, temporal, and parieto-occipital lobes from normal human brains. Biotinylated anti-human goat gamma-globulins were used as secondary antisera. A significantly greater percentage of neurons were immunostained in all the brain regions (frontal, temporal, and parieto-occipital lobes and hippocampus) incubated with sera of AD patients than with sera of DS patients or of controls. This indicates that AD patients have an excess of circulating neuron-binding antibodies (NBAs), mainly reacting with cytoplasmic structures. NBAs could be either the cause or the result of the cerebral lesion found in AD. This study is not able to answer this question, but some previous data from our own and other laboratories suggest that NBAs have a role in the pathogenesis of AD lesions. Since we found no increase of NBAs in DS patients, the brain lesions in DS appear to have a different pathogenesis.

Aged↗
PubMed1989

Peripheral neuropathy associated with mycosis fungoides.

A 56 year old man with acute sensory-motor polyneuropathy associated with mycosis fungoides is described. EMG studies showed diffuse signs of muscle denervation. A skin biopsy specimen showed a lymphocyte infiltration in the dermis, composed of mycosis cells characterised by deep invaginations of the nuclear membrane, and small Pautrier's microabscesses in the epidermis. Sural nerve biopsy revealed endoneurial fibrosis, a decreased number of myelinated fibres and acute axonal degeneration.

Biopsy↗
PubMed1988

Cryoglobulinaemic neuropathy. A clinical, morphological and immunocytochemical study of 8 cases.

Clinical, pathological and immunocytochemical studies are described for 8 patients with cryoglobulinaemia and peripheral neuropathy: 5 had essential cryoglobulinaemia and 3 secondary cryoglobulinaemia. The cryoglobulins in 2 cases were type II (mixed cryoglobulins with a monoclonal component), type III (mixed polyclonal cryoglobulins) in 2 others, and were not characterized in 4. In all patients the neuropathy had an acute or subacute onset and in 7 it was initially asymmetric but, during the illness, in 3 it gradually progressed to a symmetric sensorimotor polyneuropathy. All patients had sural nerve biopsies. In 4 there was widespread vasculitis with necrosis of vessel walls and perivascular inflammatory cells. In another 2, thickening of vessel walls and luminal narrowing without inflammatory cell infiltration, together with loss of myelinated fibres from single fascicles or focally within fascicles, suggested that the neuropathy was of vascular origin. In all patients the main pathological damage was axonal degeneration. Signs of axonal regeneration were rare. The total number of myelinated fibres was reduced in all cases, from 24 to 95% below the lower limit of normal control values. Large diameter fibres were lost preferentially in 7 patients, being below 16.5% of the total number. Several possible pathogenetic mechanisms have been suggested for cryoglobulinaemic neuropathy, including immunologically mediated demyelination and ischaemic injury due to intravascular deposits of cryoglobulins or vasculitis. Our observations therefore confirm a major role for ischaemic factors, secondary to inflammatory vascular destruction, in the pathogenesis of peripheral neuropathy in most cases of types II and III cryoglobulinaemia.

Adult↗
PubMed1988

Neuroendocrinological function in Alzheimer's disease.

The neuroendocrine function is regulated by several neurotransmitters (acetylcholine, dopamine, somatostatin and noradrenaline) known to be reduced in brains of patients with Alzheimer's disease (AD). Moreover, the hypothalamus also has pathological changes. In spite of these findings suggesting neuroendocrine dysfunctions, this function has seldom been investigated in AD patients so far. We have compared patients with clinically 'probable' AD of mild-to-moderate severity with nondemented age- and sex-matched controls. Plasma levels of prolactin (PRL), growth hormone (GH) and thyroid-stimulating hormone (TSH) were measured by commercially available radioimmunoassays (RIA) before and after stimulation with metoclopramide, l-dopa or thyrotropin-releasing hormone. Basal plasma levels of beta-endorphin and beta-lipotropin were measured by RIA after high-performances liquid chromatography. Basal and stimulated plasma levels of PRL, GH, TSH and beta-lipotropin were similar in the two groups. Basal lamina levels of beta-endorphin were significantly higher in the patient group. Of doubtful clinical importance, this might be attributed to decreased tuberoinfundibular dopaminergic activity and has also been seen in patients with Parkinson's disease.

Aged↗
PubMed1987

Peripheral neuropathy associated with experimental plasma cell neoplasm in the mouse.

In order to investigate the role of paraproteins in the production of neuropathy we experimentally induced monoclonal immunoglobulin-producing tumours into 32 BALB/c mice by injecting mineral oil or pristane intraperitoneally. In 11 mice morphologic and histometric studies of the sciatic nerve revealed the presence of neuropathy. Immunohistochemical studies did not demonstrate a significant amount of immunoglobulins and light chains in the endoneurium. The advantages and limits of this experimental model are discussed.

Animals↗
PubMed1987

Calmodulin content in human brain tumors.

Using a radioimmunoassay method, the particulate and soluble calmodulin levels were determined in biopsied specimens from normal human brain and from various human brain tumors. Both in normal and pathological tissues the major portion of calmodulin was revealed in the cytosol. The chromatographic elution profiles of calmodulin obtained from soluble and particulate fractions of the same specimen were identical, thus suggesting an identity of the supernatant and particulate form of calmodulin. In all the examined oncotypes, the calmodulin content was lower than in normal extracts and this biochemical feature could not have been correlated with the degree of malignancy of the neoplasia. Furthermore, the translocation of calmodulin from the particles to the cytoplasm, reported in other rapidly growing tumors, lacks in human cerebral ones. Our findings indicate that in human brain oncotypes the calmodulin distribution is quite different from that found in tumors taken from other tissues, where its level is increased and a positive correlation between calmodulin concentration and growth rate of neoplastic tissue has been revealed.

Adult↗
PubMed1987

Polyneuropathy in hypothyroidism: clinical, electrophysiological and morphological findings in four cases.

Clinical, neurophysiological and morphological studies of four patients with polyneuropathy and secondary hypothyroidism are reported. Neurophysiological studies revealed signs of muscle denervation and reduction of conduction velocity in all the patients. Sural nerve biopsies showed axonal degeneration in all cases but one. All the patients were treated with replacement therapy and clinical symptomatology and neurophysiological parameters improved in all patients.

Action Potentials↗
PubMed1987

Peripheral neuropathy associated with Crohn's disease.

Peripheral neuropathy in Crohn's disease has been described, to date, only with vitamin B12 deficiency or as due to oral metronidazole treatment. We report the association of Crohn's disease and peripheral neuropathy in two patients in whom neither of these pathogenetic factors of nerve damage apply. The CSF of both was normal. Patient 1 has had Crohn's disease for 12 years with predominantly sensory distal neuropathy and recurrent course related to worsening and improvement of the enteritis. Patient 2 had Crohn's disease some years before symptoms of recurrent sensory loss in the feet. Axonal degeneration was the mechanism of nerve damage in both patients.

Adult↗
PubMed1986

Plasma beta-endorphin and beta-lipotropin in patients with Parkinson's disease.

Experimental and human data in young volunteers suggest that tuberoinfundibular dopaminergic systems physiologically inhibit pituitary secretion of beta-endorphin. This hypothesis was verified in patients with Parkinson's disease, a human model of a selective deficit of dopamine. Both previously untreated patients and patients who had been without chronic treatment for 1 week showed plasma beta-endorphin levels significantly higher than those of healthy age-matched controls. Plasma beta-lipotropin levels of patients and of controls were similar. There was no correlation between plasma opioid levels and age, severity, or duration of the disease. In five patients retested during chronic treatment, plasma levels both of beta-endorphin and of beta-lipotropin significantly decreased. This decrease approximately paralleled clinical improvement. The finding that in Parkinson's disease there is a reversible disinhibition of pituitary secretion of beta-endorphin confirms that this secretion is physiologically inhibited by tuberoinfundibular dopaminergic systems.

Aged↗
PubMed1985

Potassium depletion myopathy: a clinical and morphological study of six cases.

Acute myopathy in conditions associated with endogenous or drug-induced potassium loss has been reported. We describe six patients with potassium depletion myopathy (P-DM). The clinical picture included flaccid muscle weakness without sensory loss, myalgia, polyuria, and polydipsia. All the cases had markedly increased serum creatine kinase (CK) levels. The most consistent pathological characteristics were phagocytosis of degenerating muscle fibers plus fiber regeneration. Atrophy of type 2 fibers was observed. Vacuoles and vesicular elements originating from T-tubules were also encountered. The clinical manifestations and morphological changes had reversed after potassium repletion. Both constriction of vascular smooth muscle and cellular energy failure may be pathogenetic factors in P-DM.

Adult↗