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Biomedical subjects

G Said

Publications and source records attributed to G Said.

At least 73 records · Page 4Linked to original sources
PubMed1993

Experimental carcinomatous plexopathy.

To understand the pathophysiology of carcinomatous plexopathy better, we studied nerve lesions induced by an experimental thyroid carcinoma implanted over the brachial plexus in 30 Fisher rats. We performed a morphological study including light and electron microscopic examination and teased fibre preparations of brachial plexuses from implanted and control animals. The control side was normal in all. A large tumour always grew within 2 months in all implanted animals and a third of the rats eventually developed weakness of the corresponding anterior limb extremity. On gross examination the tumour always surrounded the brachial plexus, which showed a variety of microscopic abnormalities, ranging from isolated endoneurial oedema to total degeneration of nerve fibres in 41% of the implanted rats. The most frequent lesions consisted of segmental demyelination associated with endoneurial oedema at the site of compression. Some axons degenerated distally and regeneration by sprouting of the proximal stump was noted 80 days after implantation. All subpopulations of nerve fibres were equally affected. Invasion of the intrafascicular area by the tumour was an uncommon finding, in comparison with the constant entrapment of the branches of the plexus by the tumour. This invasion by the tumour induced demyelination of nerve fibres at the site of compression, and sometimes at a distance from the tumour. Regeneration did not occur when the tumour had invaded the intrafascicular area.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Late-onset familial amyloid polyneuropathy with the TTR Met 30 mutation in France.

Four unrelated French cases of familial amyloid polyneuropathy are reported. Clinical onset ranged from the sixth to the ninth decade. Sensory signs were predominant initially in the lower limbs; motor changes, and in one case autonomic involvement, appeared later. Amyloid disease was clinically limited to the peripheral nervous system. In two cases, there was no evidence of familial disease. DNA analysis was performed in these four patients and in two children of Patient 1. Restriction analysis of amplification products of exon 2 of the transthyretin gene was positive for the valine 30 to methionine mutation. These four unrelated patients live in different areas of France. Further studies are needed to determine whether these mutations have a common origin and whether they are related to the Portuguese mutation.

Aged↗
PubMed1993

Transthyretin gene mutations in British and French patients with amyloid neuropathy.

Five patients, two British and three French, with late onset amyloid neuropathy were found to have mutations of the transthyretin (TTR) gene associated with the Portuguese and German types of familial amyloid polyneuropathy. Familial amyloid polyneuropathy is rare in the United Kingdom and has not previously been defined at a molecular genetic level. None of the patients had a history of affected antecedents; the role of TTR gene analysis in diagnosing known or suspected amyloid neuropathy, regardless of family history or ethnic background, is emphasised.

Aged↗
PubMed1993

[Type II carnitine palmitoyl transferase deficiency complicated by acute respiratory failure].

Carnitine palmitoyl transferase (CPT) deficiencies can realise distinct clinical presentations. The best known is the muscular form with episodic muscle necrosis and paroxysmal myoglobinuria after prolonged exercise, in young adults, and results from decreased CPT II activity. In this paper, we report on an observation of a patient with a severe CPT II deficiency who presented a respiratory failure during an attack of muscle necrosis. The severity of the symptomatology were associated with a conspicuous reduction of CPT II residual activity in leucocytes and in fibroblasts. Fasting test showed an hypoketogenesis. These results support the concept that CPT II deficiency is ubiquitous, even though injury is restricted to the skeletal muscle.

Adolescent↗
PubMed1993

[Demyelinating nervous lesions in myalgia-eosinophilia syndrome induced by L Tryptophan].

A case of severe peripheral nerve lesions in a patient with eosinophilia-myalgia syndrome induced by L-Tryptophan is reported. Both superficial radial nerves were very tender on palpation. Biopsy of the radial nerve showed myelin abnormalities of the type observed in experimental chronic nerve entrapment. Nerve lesions included asymmetrical distortion of the myelin sheath, segmental demyelination, axonal degeneration and regeneration. Such abnormalities suggest that mechanical factors, presumably due to proliferation of connective tissue, play a role in the nerve lesions observed in this patient.

Demyelinating Diseases↗
PubMed1992

Severe early-onset polyneuropathy in insulin-dependent diabetes mellitus. A clinical and pathological study.

BACKGROUND AND METHODS: The pathophysiologic features of diabetic neuropathy, a common and disabling long-term complication of diabetes mellitus, are poorly understood. We studied five patients, 22 to 34 years old, in whom an uncommonly severe symmetric polyneuropathy developed soon after the onset of insulin-dependent diabetes. Their autonomic function and nerve conduction were studied, and sural-nerve biopsy specimens were examined by light and electron microscopy. Other causes of neuropathy were carefully excluded. RESULTS: Four patients had autonomic dysfunction with postural hypotension, fainting, diarrhea, and Argyll Robertson pupils and peripheral neuropathy with loss of sensation of pain and changes in temperature that followed a pattern suggestive of a length-dependent degeneration of nerve fibers. In contrast, the fifth patient had muscle weakness and atrophy of limb extremities, with "glove and stocking" sensory loss, but little autonomic dysfunction. In the biopsy specimens of sural nerves, the mean (+/- SD) density of myelinated fibers was reduced to 20 +/- 14 percent of that measured in five control patients, and the density of unmyelinated fibers was reduced to 6 +/- 4 percent of that in the controls. Regenerating fibers accounted for 38 +/- 11 percent of the myelinated axons. Abnormalities of the myelin sheath affected 33 +/- 21 percent of the isolated fibers, and axonal degeneration 11 +/- 8 percent. Dying-back fibers, a characteristic of the centripetal degeneration of peripheral axons, were also identified. The dying-back process progressed at the rate of a few hundred micrometers per day. CONCLUSIONS: Early-onset symptomatic polyneuropathy in patients with diabetes mellitus is characterized by the loss of both myelinated and unmyelinated nerve fibers. Spontaneous axonal regeneration is remarkably frequent, even when neuropathy is severe.

Action Potentials↗
PubMed1992

[Peripheral neurologic manifestations of infection by the human immunodeficiency virus].

Peripheral nerve lesions observed in the progressive immunodeficiency associated with infection are remarkable for their diversity and their potential severity. At the onset, demyelinating neuropathies predominate, often with signs of atypical polyradiculoneuritis associated with inflammatory lesions or vasculitis sometimes of the necrotizing type, as that observed in periarteritis nodosa. Later on, at the immunosuppression stage, axonal lesions predominate. At the AIDS stage one may find lymphomatous infiltration of nerves and nerve roots and, chiefly, opportunistic cytomegalovirus (CMV) infection. This infection produces meningoradiculitis, mainly in the territory of the cauda equina, or multifocal neuropathy frequently associated with CMV retinitis. Early treatment of CMV neuropathies may stabilize the lesions or even result in functional improvement, but the overall prognosis of late neuropathies remains poor.

Cell Division↗
PubMed1992

Asymptomatic nerve hypertrophy in lepromatous leprosy: a clinical, electrophysiological and morphological study.

In order to learn more about early nerve lesions observed in leprosy, we performed a clinical, electrophysiological and morphological study in seven patients with untreated lepromatous leprosy, palpably enlarged radial cutaneous nerve and preserved sensation in the corresponding territory. The conduction velocity of the cutaneous radial nerve, which was decreased in all patients, did not significantly differ from that of a group of patients with lepromatous leprosy, hypertrophy of the radial cutaneous nerve and sensory loss. In contrast, the sensory action potential was significantly lower in patients with sensory loss, which demonstrates that axon loss is more important than demyelination in producing sensory loss. In all patients nerve enlargement was due to thickening of the epineurium and of the perineurium subsequent to inflammatory infiltrates and proliferation of fibroblasts and perineurial cells. In several fascicles, the inflammatory infiltrates and the infected cells infiltrated endoneurial connective tissue septa and blood vessels. Mycobacteria leprae were abundant in perineurial cells, fibroblasts, macrophages, Schwann cells and endothelial cells, and lymphocytic vasculitis present in all cases. The average density of myelinated fibres was 2600 SD 880 fibres/mm2 (control: 7700 fibres/mm2), with marked differences between individual fascicles, versus 420 fibres/mm2 in patients with nerve hypertrophy and sensory loss (range 0-2080 fibres/mm2). Single fibre preparations showed that segmental demyelination predominated in two patients, axonal degeneration in one, while inflammatory infiltrates and proliferation of connective tissue adhering to individual fibres were prominent in the others.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1992

Muscle siderosis in AIDS: a marker for macrophage dysfunction?

We have observed numerous iron granules in muscle fibres, endothelial cells and macrophages of muscle biopsy specimens of 21 out of 41 AIDS patients with different patterns of muscle involvement. All patients were severely immunodepressed. We report on our findings and discuss the mechanism of muscle siderosis that may point to deterioration of some functions of macrophages at a late stage of HIV infection.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Autonomic neuropathy and immunological abnormalities in Chagas' disease.

Chagas' disease (American Trypanosomiasis) is caused by infection with the haemoflagellate parasite Trypanosoma cruzi, which is transmitted from animals to man by the Reduviidae bug. The human disease is characterized by two phases. In the first (acute phase) parasitaemia is high and general symptoms variable. The next, which is lifelong (chronic phase), is characterized by inflammatory lesions in cardiac and skeletal muscle, gastrointestinal, the autonomic nervous system. Parasites are difficult to detect in blood and affected tissues. Lesions within the autonomic nervous system, lead to development of cardiomyopathy, megaoesophagus and megacolon. The discrepancy between the profusion of inflammatory lesions and the absence of parasites suggests the development of autoimmunity probably of a cell-mediated type. Several autoimmune abnormalities have been noted during Trypanosoma cruzi infection. These include suppression of the specific response to autoantibodies directed against antigens located in the endocardium and in nerves, and development of cell-mediated immunity against host antigens (cytotoxic T- and delayed type hypersensitivity T-cells). These autoimmune disorders are thought to be responsible for much of the pathological damage in chronic Chagas' disease.

Animals↗
PubMed1992

[Demonstration of genetic mutation in most of the amyloid neuropathies with sporadic occurrence].

The Portuguese type of familial amyloid polyneuropathy (FAP type I) is a disabling autosomic dominant disorder, which is caused by a point mutation in the transthyretin (TTR) gene. Other TTR gene mutations have been reported recently in other FAP. In the absence of monoclonal gammopathy, sporadic amyloid neuropathies raise a problem for their pathogenicity. In this study, we have looked for TTR gene mutations in apparently sporadic cases of amyloid polyneuropathy by Southern's technique. All the patients were of french origin. None had monoclonal gammopathy. The mean age at onset was 64 (50 to 79 years). Most of the patients (9/1) were male. Five patients were found to carry FAP type 1 mutation, and 2 the tyr 77 (German) mutation. This study suggests that investigations in amyloid polyneuropathy with no overt family history should include systematic DNA analysis.

Adult↗
PubMed1991

Cytomegalovirus neuropathy in acquired immunodeficiency syndrome: a clinical and pathological study.

We have observed typical cytomegalovirus cytopathology associated with multifocal inflammatory and necrotic lesions of peripheral nerve in biopsy specimens from 4 patients who developed a rapidly progressive, multifocal neuropathy late in the course of human immunodeficiency virus infection. The inflammatory infiltrates, which contained numerous polymorphonuclear cells, were associated with mixed, axonal, and demyelinative lesions of nerve fibers. One of these patients improved on treatment with DHPG (9-[2-hydroxy-l(hydroxymethyl) ethoxymethyl] guanine) and remains stable after 18 months. The other 3 died soon after the onset of the neuropathy. In another patient with acquired immunodeficiency syndrome, who developed a severe, predominantly motor neuropathy of the lower limbs, the nerve biopsy did not reveal cytomegalovirus inclusions, but the neurological deficit improved on treatment with DHPG. The patient died from cachexia 2 months later; numerous cytomegalovirus lesions were found in the spinal cord at the time of postmortem examination. The multifocal necrotic endoneurial nerve lesions with polymorphonuclear cell infiltration we describe may help identify cytomegalovirus neuropathy when characteristic inclusions are not present in the biopsy specimen.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Vulnerability of nerve fibres to ischaemia. A quantitative light and electron microscope study.

In order to learn more about the vulnerability of nerve fibres to ischemia, a quantitative study of nerve fibre abnormalities was performed on biopsy specimens of the superficial branch of the peroneal nerve from 26 patients with vasculitic neuropathy: 20 had necrotizing arteritis, 5 a lymphocytic, and 1 a leucocytoclastic vasculitis on nerve and/or muscle biopsy. The density of myelinated fibres ranged from 25 to 7880 per mm2 (n = 8470 +/- 706 (SD]. There was a marked inequality in the density of nerve fibres between the fascicles of individual nerves with a mean coefficient of variation of 41 +/- 37 (SD) % versus 7.4 +/- 3.0% in controls. Loss of myelinated fibres, which was greater for fibres larger than 7 microns in diameter, was more severe than that for unmyelinated axons. Regeneration, which was assessed by the number of clustered axons, decreased when the density of myelinated fibres decreased, suggesting that severe nerve ischaemia precludes axonal regeneration. Wallerian degeneration affected on average 58% (range 5-100%) and segmental demyelination, mainly of the secondary type, on average 1.94% (range 1-10%) of teased fibres. It was concluded that (1) myelinated fibres are more vulnerable to ischaemia than unmyelinated axons; (2) large myelinated fibres are affected before the smaller ones; (3) segmental demyelination is uncommon in this context; (4) severe nerve ischaemia precludes axonal regeneration.

Adult↗
PubMed1990

Dominantly transmitted congenital indifference to pain.

Two patients from a family with dominantly inherited indifference to pain were investigated. Perception of the other sensory modalities was normal as was the remainder of the neurological examination. Electrophysiological studies and morphometric evaluation of myelinated and unmyelinated fibers of nerve biopsy specimens were normal. This is the first morphometric study of peripheral nerve in dominantly inherited indifference to pain.

Adult↗
PubMed1989

Molecular genetics of amyloid neuropathy in Europe.

The Portuguese type of familial amyloid polyneuropathy (FAP type I), a disabling autosomal dominant disorder with onset in early adult life, is caused by a point mutation in the transthyretin (TTR; previously known as prealbumin) gene. DNA analysis in thirteen European families (one British, two French, one Italian, one Greek, and eight Cypriot) showed that members of all those from Cyprus and Greece, and one from France, carried the FAP type I mutation. Patients from seven of these ten kindreds were not known to have a genetic disease before this study, which demonstrated the mutation in 16 of 43 clinically unaffected relatives. 2 of these were aged over 50 years. TTR gene analysis has useful applications in genetic counselling, including prenatal diagnosis, in identifying the cause of seemingly sporadic cases of amyloid neuropathy, and in epidemiological studies of FAP.

Adult↗