Effects of pancreatic transplantation on diabetic polyneuropathy.
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Biomedical subjects
Publications and source records attributed to G Comi.
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Alloalbumin Tagliacozzo (313 Lys------Asn) was detected in the cerebrospinal fluid of a 27-yr-old woman. We studied this rare finding by means of high-resolution electrophoresis, isoelectric focusing, and immunofixation. We herein discuss the importance of molecular mass versus superficial electrical charge in the transfer of plasma proteins through the blood-brain barrier.
Brain magnetic resonance imaging (MRI), multimodality evoked potentials (EPs) and cerebrospinal fluid examination were performed in 42 patients with myelopathy of undetermined aetiology in order to detect abnormalities usually related to multiple sclerosis (MS). Patients were divided into three groups: insidious-onset myelopathy with only motor signs (group A; 11 patients), with both motor and sensory signs (group B; 18 patients) and acute-onset myelopathy (group C; 13 patients). Multiple brain MRI lesions were found in 18 patients (2 of group A, 13 of group B and 3 of group C). Another 7 patients had a single white-matter lesion. Visual EPs were abnormal in 21 and brain-stem auditory EPs in 12 patients. Paraclinical tests supported the diagnosis of MS in 25 patients (60%) by showing subclinical brain abnormalities. Oligoclonal bands were found in 16 of these 25 patients. The findings strongly suggest a diagnosis of MS in the patients of group B.
The paper deals with methods of processing ECG and respiration signals which aim at detecting parameters whose values may be correlated to normal and diabetic subjects with or without cardiovascular autonomic neuropathy (CAN). Beat-to-beat R-R duration values of the ECG and discrete series of respiration are obtained from original signals using a recognition algorithm. Power spectrum analysis (autospectra, cross-spectra and coherence via autoregressive modelling) is carried out on segments of about 200 consecutive cardiac cycles. Spectral parameters of the R-R variability signal are obtained as follows: total power, powers of low-frequency (LF) and high-frequency (HF) components, power of the signal which is (or is not) coherent with respiration, in absolute or in percentage values. The experimental protocol considers 40 diabetic patients (21 of whom have diabetic neuropathy) and 14 normals in three different conditions: resting, standing and controlled respiration. The developed spectral parameters seem sensitive enough to differentiate between normal and pathological subjects. These parameters may constitute a quantitative means to be added to the classical diabetic tests for the diagnosis of cardiovascular autonomic neuropathy.
Spectral analysis of short term R-R variability estimated by autoregressive modelling is a recently developed method for the evaluation of cardiovascular autonomic function. This new test also allows to study the interaction on heart rate variability of parasympathetic and sympathetic system. The sensitivity of the method for detection of cardiovascular autonomic neuropathy has been evaluated in a group of diabetic patients in comparison with the sensitivity of a battery of the most commonly used cardiovascular autonomic tests (deep-breathing, lying-to-standing, Valsalva Manoeuvre, postural hypotension and hand grip). Spectral analysis of heart rate variability resulted in a very sensitive method for early detection of diabetic autonomic neuropathy, about one-fourth of diabetic patients with normal traditional cardiovascular autonomic tests had abnormal results at spectral analysis. Both sympathetic and vagal control of heart rate resulted alterated in diabetic autonomic neuropathy.
To test the effect of sampling on the detection of immunoglobulin (Ig) cerebrospinal fluid (CSF) abnormalities, we analyzed the first and last 1 ml fraction of 10 ml obtained during a single CSF removal from 27 multiple sclerosis (MS) patients and six patients with other neurological diseases. IgG index, hyperbolic function, and IgG synthesis rate decreased between the first and the last CSF aliquot. Discordant results were found in 4/27 (15%) MS patients. In 2/27 (7.5%) clinically definite MS patients, the number of CSF oligoclonal bands (OCB) decreased between the first and the last fraction. In one of the two patients, the three OCB visualized in the first fraction were not found in the last. We conclude that fractionated sampling may partially account for the absence of OCB in the CSF of some definite MS patients.
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Limb lengthening is used to correct leg length discrepancy and to increase stature. The reported frequency of peripheral nerve complications varies from 5% to 30%, but is probably underestimated. Damage may be direct or be caused by overstretching of the nerves. We have used electrophysiological tests to evaluate five patients during bilateral tibial lengthening by the Ilizarov method. Results after 24 to 107 days of lengthening showed electromyographic evidence of partial muscle denervation in all 10 limbs, with reduced motor conduction velocities in two tibial nerves and three common peroneal nerves. The sensory conduction velocity in the sural nerve was always unchanged. A clear relationship was shown between the amount of tibial lengthening and the degree of electrophysiological abnormality. Our results suggest that subclinical nerve damage is a very frequent complication of tibial lengthening.
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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.
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.
Muscle glucose-6-phosphate dehydrogenase (G6PD) deficiency is described in four clinically heterogeneous patients: an athlete who developed myoglobinuria after physical exercise; a 7-year-old, mildly mentally retarded boy, who had episodes of dark urine and high creatine kinase; and two brothers of Sardinian origin, the elder showing moderate exercise intolerance. Histochemical and biochemical studies showed a lack of G6PD activity in muscle biopsy specimens as well as in erythrocytes. G6PD characterization in erythrocytes classified these mutant enzymes as Mediterranean variant in all the patients. The deficiency was confirmed in the patients' myotubes and skin fibroblasts, where residual activity was present. Electrophoretic studies in tissue culture extracts showed that the residual muscle enzyme migrated as a single electrophoretic band like normal human muscle G6PD.
A 19-year-old man born with thyroprivic hypothyroidism, due to congenital development defect, manifested hypogonadism, stunted growth, chronic progressive external ophthalmoplegia (CPEO), diffuse muscle weakness and wasting, right bundle branch block, cerebral atrophy. Muscle biopsy showed mitochondrial abnormalities. Biochemical investigations on muscle disclosed partial (50%) cytochrome c oxidase deficiency, 58% decrease of cytochrome aa3 and 41% decrease of cytochrome b. Enzyme-linked immunosorbent assay showed decrease of the immunologically active enzyme protein.
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.
Eight patients with stable Behçet's disease were studied by means of multimodality evoked potentials and magnetic resonance imaging to evaluate the possibility of an earlier and objective demonstration of clinical and subclinical Central Nervous System (CNS) involvement. It was shown that both diagnostic techniques are useful for quantitative evaluation of neurological involvement in Behçet's disease; of particular interest was the demonstration of subclinical CNS changes.
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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.
The brainstem auditory evoked potentials of 84 epileptic patients in chronic monotherapy with carbamazepine (n = 36), phenobarbital (n = 19), Na-valproate (n = 20) or progabide (n = 9) were studied. The mean values of I-III and I-V interpeak latencies (IPLs) were respectively 2.16 +/- 0.11 and 4.03 +/- 0.17 in the control group, 2.31 +/- 0.09 and 4.17 +/- 0.16 in the valproic group, 2.30 +/- 0.17 and 4.19 +/- 0.20 in the carbamazepine group, 2.17 +/- 0.16 and 4.10 +/- 0.18 in the phenobarbital group and 2.16 +/- 0.11 and 4.12 +/- 0.17 in the progabide group. The prolongation of I-III and I-V IPLs was statistically significant only for the valproic acid and carbamazepine groups. Neither duration of the epilepsy and treatment and frequency of seizures nor the serum drug levels were correlated with I-V IPL values.