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Biomedical subjects

A Simonati

Publications and source records attributed to A Simonati.

At least 37 records · Page 2Linked to original sources
PubMed1997

DNA fragmentation in normal development of the human central nervous system: a morphological study during corticogenesis.

Refinement of the cell number by programmed cell death is a major morphogenetic mechanism of the developing central nervous system (CNS) in vertebrates including mammals, which determines to a significant degree its mature cytoarchitecture. We have examined the topography and the extent of cell death in different regions of the human CNS prenatally (11 fetuses), and in the early post-natal weeks (three newborns). Attention was focused on the wall of the telencephalon during a relatively short time period (12th-23rd week of gestation), corresponding to the time of major proliferation in the ventricular zone and to the peak of neuronal migration; both these mechanisms are crucial for corticogenesis. The TUNEL method was used, allowing the recognition of cell death because of its ability to label blunt ends of double-stranded DNA breaks. Morphological features of nuclei at different stages of apoptosis were identified, providing better evidence of the extent of the process than histological stains. Cell labelling was seen in either post-mitotic elements in the ventricular zone, or along the migratory pathways in the intermediate zone and subplate at all prenatal ages examined. No apoptotic nuclei were seen in the cortical plate. These findings suggest that apoptotic cell death drives the selection of cells which are committed to play a role during the early stages of corticogenesis. Lack of evidence of clonally related apoptotic cells also indicates that cell death occurs randomly. Therefore, molecular signals from the surrounding microenvironment seem to be necessary for the apoptotic pathway to be turned on, thus determining the fate of post-mitotic cells.

Aging↗
PubMed1994

Microgyria associated with Sturge-Weber angiomatosis.

A case is reported of an infant affected with Sturge-Weber disease who underwent left hemispherectomy due to untreatable seizures when 97 days old. Pathological analysis of the surgical specimens revealed the presence of four-layered microgyric cortex below the angiomatosis, intense gliosis, and the presence of calcifications of both the abnormal cortex and the underlying white matter. These findings suggest that the early infantile form of Sturge-Weber disease is associated with a developmental disorder of the cortical organization. Such abnormalities are consistent with the presence of an epileptogenic condition that is unresponsive to pharmacological treatment.

Atrophy↗
PubMed1993

Clinical features of Kleine-Levin syndrome with localized encephalitis.

We report the clinico-pathological findings regarding a 9 year-old girl with some clinical features of Kleine-Levin syndrome who died suddently as a result of pulmonary embolism in the course of femoro-iliac thrombophlebitis. Neuropathological examination provided evidence of perivascular inflammatory infiltrates and microglial proliferation of nodular type located in the diencephalon and midbrain. These findings suggest that a localized encephalitis may be the underlying condition in Kleine-Levin syndrome.

Brain Mapping↗
PubMed1988

Blood lymphocytes in neuronal ceroid lipofuscinosis.

Ultrastructural examination of white blood cells of 8 patients with neuronal ceroid lipofuscinosis showed the characteristic cytosomes, i.e. curvilinear bodies, fingerprint profiles, osmiophilic bodies, as seen in nerve cells. The reliability of this simple technique in the diagnostic work-up of this progressive neurodegenerative disorder is emphasized.

Child↗
PubMed1988

Cerebro-ocular dysplasia and muscular dystrophy: report of two cases.

The authors report two cases with severe cerebro-ocular malformations and muscular dystrophy who died at 14 and 8 months of age. In both, muscular dystrophy was confirmed by EMG and high muscle enzyme values. In one case, autopsy showed severe cerebral malformation consisting of lissencephaly, hydrocephalus, agenesis of corpus callosum, chiasma and olfactory bulb and lobe, absence of pyramides and cerebellar vermis. In sections of cerebral cortex a clear absence of structural cellular organization and spongiosis of the white matter were evident. Similar disorganization was found in the cerebellum where numerous calcifications were present. The muscle showed signs of primitive muscular dystrophy. The clinical autonomy of the cerebro-ocular-dysplasia-muscular-dystrophy syndrome is discussed. The clinical and pathological data are compared with the two other similar syndromes (i.e. Fukuyama's and Warburg's diseases).

Abnormalities, Multiple↗
PubMed1985

Chronic inflammatory demyelinating polyneuropathy.

In 12 cases of CIDP under surveillance for 14 years, the main nerve biopsy findings were endoneural oedema and demyelination of nerve fibres. IgM deposition was found in 1 patient and IgG deposits in another. Electron microscopy revealed proliferation of the Schwann cells and mononuclear cell infiltration. The diagnostic criteria and nerve biopsy findings in CIDP are listed in the tables.

Adolescent↗
PubMed1984

Changes in terminal sprout formation in rat sternocostalis muscle during chronic intoxication with 2,5 hexanedione.

Qualitative and quantitative morphological studies of the sternocostalis muscle innervation were made on rats chronically intoxicated with 2,5 hexanedione (2,5 HD) using the zinc iodide-osmium (ZIO) technique. Two distinct phases were seen in the events at the motor endplate. First, the number of motor endplates forming spontaneous terminal sprouts was found to increase linearly with time and, from the third week onward, the sprouts appeared to become progressively elongated. This latter change was associated with the appearance of swollen axons within intramuscular nerve bundles. Second, from the sixth week onward, wallerian degeneration of nerve fibers was seen and terminal sprouts began to make new arborizations on muscle fibers. By the eighth week, this occurred in as many as 66% of the rats, and collateral sprouting was also observed at this time. The occurrence of increased spontaneous terminal sprouting due to altered neuromuscular function is discussed in the light of axonal changes resulting from neurofilament accumulation following 2,5 HD intoxication.

Animals↗
PubMed1983

The effects of 2,5-hexanedione on axonal regeneration after nerve crush in the rat.

The pattern of recovery of myelinated axons in the posterior tibial nerve after crushing was studied in rats chronically intoxicated with 2,5-hexanedione. It was given for 2 weeks before crushing (200 mg/kg i.p. 5 times a week) or additionally for two further weeks after the nerve crush. Two animals were examined from each group at approximately 1,2,3,4 and 8 weeks later. Return of function in poisoned animals was slower than in the controls. The numbers of regenerating myelinated fibres was severely reduced in poisoned animals up to 4 weeks later, but by 8 weeks the numbers equalled those in the control nerves. Marked impairment of initiation of neurite outgrowth was found, but once begun, axonal growth was comparable to controls and myelination occurred normally. Above the crush for 10 mm, filament-filled axonal swellings were found in poisoned animals accompanied by varying amounts of retrograde axonal degeneration. These findings are discussed in relation to the role of normal neurofilaments in axonal growth and the effects of probably cross-linking of these by 2,5-hexanedione on regenerating neurites.

Animals↗
PubMed1983

Choroid plexus papilloma of the cerebello-pontine angle.

The clinical symptoms, neuroradiological findings and post-operative course is described in four patients affected with a choroid plexus papilloma of the cerebello-pontine angle. Clinical criteria (such as the early onset of signs and symptoms of raised intracranial pressure, and the early impairment of the auditory function) and the neuroradiological pictures (the lack of bone lesions, the tumour appearance as a hypodense mass on CT scan, which is well-enhanced after contrast injection) help the neurosurgeon to predict the surgical findings, but they cannot be considered as definite. The prognosis of such tumours is related more to the difficulties of the surgical intervention than to the peculiar properties of the growth.

Adult↗
PubMed1982

Neurotoxic action of 2,5-hexanedione on the autonomic nervous system: ultrastructural and functional alterations in the rat sympathetic superior cervical ganglion.

In rats treated for 14 days with 2,5-hexanedione, the efficiency of ganglionic transmission was markedly reduced whereas only faint ultrastructural changes occurred in a few preganglionic fibers; evident signs of axonal pathology were observed on the 30th day of treatment. Choline acetyltransferase activity and acetylcholine formation showed no alteration at any time. The autonomic system is affected early during 2,5-hexanedione neuropathy, functional changes being more marked than morphological lesions.

Acetylcholine↗
PubMed1982

Congenital toxoplasmosis: histological and ultrastructural study.

A case of congenital toxoplasmosis is reported in which the patient died at 32 days following seizures, coma and respiratory disturbances. Neuropathological examination showed numerous foci of softening throughout the brain. Histological examination disclosed widespread areas of inflammatory necrosis. Circumscribed areas of granulomatous inflammation were also found. Cysts containing a variable number of microorganisms and toxoplasmas free in the damaged areas were frequently observed. Small calcifications were scattered in the cerebral cortex and basal ganglia. Electron microscopy of postmortem brain specimens demonstrated toxoplasmas at various stages of development. The microorganism is enveloped by a two-layered membrane, the pellicle. Replication occurs in a vacuole inside the host cell. Following replication the newly formed parasites, the trophozoites, are released. Several replications without release may also occur with consequent cyst formation. The motile form of the toxoplasma, the tachyzoite, is fusiform with truncated cone shape of the anterior ending which is the presenting surface modified for host cell penetration. The modality of transplacental transmission and the clinical syndromes associated with toxoplasma infection are discussed. EM even of post mortem material contributes to knowledge of the structure of the parasite and of its life cycles.

Brain↗
PubMed1981

An unusual case of meningeal gliomatosis.

A case of meningeal gliomatosis following a primary spinal cord tumor is reported. The clinico-pathological features of this unusual extension of a spinal glioma are described. The rare incidence of this malignancy and its occurrence in young patients only are stressed. The possible pathophysiological events leading to the diffuse dissemination of the neoplastic cells are discussed.

Adult↗
PubMed1981

Lumbar epidural Ewing sarcoma. Light and electron microscopic investigation.

The clinicopathological findings in a child with extraskeletal Ewing sarcoma are described. The patient complained of pain in the lower back and difficulty walking. An extraskeletal, epidural, friable tumor, 2-3 cm long was removed from the epidural space. It had no relationship with the bone structures. Light and electron microscopic examination of the tumor led to the diagnosis of Ewing sarcoma. The morphological aspects of this neoplasia and the problem of the differential diagnosis with other small cell tumors of the epidural space are discussed.

Adolescent↗
PubMed1981

Gliomatosis cerebri diffusa. A case report.

The clinico-pathologic findings in an additional case of gliomatosis cerebri are reported: a 60-year-old woman died 8 months after the onset of a progressive deterioration of both the neurologic and mental conditions. Neuropathologic examination disclosed wide demyelination of both hemispheres, communicating through the corpus callosum, extending downward along the internal capsule to the brainstem structures. Cellular stains showed the presence of elongated astrocytes, multinucleated cells, mitotic and anaplastic figures, involving the demyelinated areas and the neighboring regions, and allowed the diagnosis of gliomatosis cerebri diffusa. The nosologic and pathogenetic aspects of this rare entity are discussed.

Autopsy↗
PubMed1981

Neurotoxic effects of 2,5-hexanedione in rats: early morphological and functional changes in nerve fibres and neuromuscular junctions.

The study was directed at detecting changes occurring in the early stages of the neurotoxic process induced by an intensive treatment with 2,5-hexanedione. Rats were injected intraperitoneally each day with 450 mg/kg of body weight for the first 14 days and then with 300 mg/kg for an additional 20 days. After 34 days of treatment typical axonal lesions were observed in the sciatic branches, together with electrophysiological signs of denervation in several fibres of the leg muscles. Morphological changes were also found in axons of the spinal cord and optic tracts. At an earlier stage (days 13 to 18), when clinical signs appeared, in the absence of morphological changes in peripheral nerves and of denervated muscle fibres, significant alterations in the functioning of several neuromuscular junctions were observed: increase in frequency and amplitude of miniature end-plate potentials, reduction of the mean quantal content of the evoked end-plate potential (epp) and absence of epp's in some fibres. These changes indicate a progressive functional impairment of nerve terminals which could possibly represent: (a) a primary alteration of the membrane resting and action potentials; (b) a secondary effect of changes in axonal transport. Both these hypothetical events could result from the inhibition of glycolitic enzymes of nervous tissue by 2,5-hexanedione.

Animals↗
PubMed1978

[Experimental neuropathy due to acrilamide. Histological and ultrastructural studies (author's transl)].

The effects of acrylamide intoxication were studied both in peripheral (PNS) and central (CNS) nervous system of rats. The animals were sacrified at different time intervals from the beginning of the intoxication. Histological and ultrastructural studies of peripheral nerves and long tracts of the spinal cord revealed a severe axonopathy, characterized by swelling of axons, particularly in the paranodal regions due to accumulation of neurofilaments with almost complete disappearance of neurotubules. There was also aggregation of dense bodies, swollen mitochondria and multivescicolar bodies in subaxolemmal regions. Presynaptic endings in the anterior horns of the spinal cord and in the cuneate nuclei were swollen and filled with packed filaments. Fiber degeneration at different stages was seen both in PNS and in CNS. These changes are not specific for acrylamide intoxication, having been observed in other experimentally induced neuropathies (n-hexane, Mn-BK, CS2, ...), as well as in a variety of diseases both genetically determined and due to exposure to toxic substances (glue-sniffing, leather cement poisoning, antiblastic therapy, ...). Accumulation of filaments in peripheral and central axons is the pattern of fiber degeneration characterizing the dying-back neuropathies. These axonal changes are particularly marked in the pacinian bodies as well as in the distal segments of the fibres. These data support the hypothesis that a dying-back neuropathy might depend on the direct effect of the toxic substance on the most vulnerable segments of the fibres, rather than on the perikaryon of the nerve cell, as previously supposed.

Acrylamides↗
PubMedDate not supplied

Ponto-cerebellar hypoplasia with dystonia: clinico-pathological findings in a sporadic case.

Microcephaly, absent psychomotor development and dystonic limb movements were the main clinical features of a 3-year-old girl affected by hypoplasia of the pontocerebellar structures. As in the few previously reported cases there are discrepancies between the severity of lesions in the supratentorial and infratentorial compartments. Pathological features such as size reduction of the ventral pons, inferior olive atrophy, dentate nucleus fragmentation, and thinning of the cerebellar cortex suggest an impaired maturation of the involved structures due to a prenatal condition (dated at about 20-28 weeks of gestation). Somatotopic analysis failed to provide conclusive evidence on the primary target of the disease. The affected structures originate from the dorsal rhombencephalic region at about the same gestational age, and their maturation is probably under the control of sets of genes which regulate pattern formation. Early abnormal functioning of such genes might lead to the selected morphogenetical alterations observed in ponto-cerebellar hypoplasia. The normal morphogenetic pattern of the supratentorial structures and the mild lesions observed suggest that their late involvement can be related to a different pathogenetic process.

Atrophy↗