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Biomedical subjects

A Colombi

Publications and source records attributed to A Colombi.

At least 73 records · Page 4Linked to original sources
PubMed1981

Carbon disulfide neuropathy in rats. A morphological and ultrastructural study of degeneration and regeneration.

The aim of this study was to elucidate the site and detailed nature of peripheral nerve damage induced in the rat by chronic CS2 inhalation exposure in the light of the relationship between pathological and neurophysiological data. Adult male rats were exposed to 700 ppm of CS2 2 h/d, 5 d/week for 12 weeks and then followed-up for 18 weeks. The first alteration observed was a decrease in the nerve conduction velocity, discovered after only 3 weeks of exposure. Pathological lesions were first observed in the 10th week and consisted of a typical "giant axon" axonopathy. Obvious pathological lesions of the myelin sheaths were revealed much later, in the 3rd week after the end of exposure, when some nerve fibers were dying back. Recovery took place with the regeneration of new fibers which started in the 8th week after the end of exposure and was nearly complete in the 18th week. These findings demonstrate that CS2-induced polyneuropathy is an axonopathy very similar to that caused by other occupational neurotoxic agents like MnBK, n-hexane, and acrylamide. The timing of the pathological events within the nerve fibers suggests that the pathogenesis of the nerve lesions should probably be attributed to a primary energy failure of the axonal membrane induced by CS2.

Animals↗
PubMed1981

Effects of ganglioside therapy on experimental CS2 neuropathy.

Both in animals and in man the inhalation of CS2 vapor induces a chronic polyneuropathy with primary lesions in the axons of peripheral nerves. Since it was reported in several studies that the administration of gangliosides improves nerve regeneration and the functional recovery of nerves damaged by section as well as cryodegeneration, a study was undertaken to evaluate the effects of bovine-brain gangliosides administration on the experimental CS2 neuropathy in the rat. One hundred and fifty male rats were intoxicated with CS2 by a discontinuous inhalation exposure to 700 ppm for 12 weeks until a clear neuropathy developed. Thereafter the animals were subdivided at random into five groups and treated in different ways: 10 mg/kg BW gangliosides, 0.5 mg/kg gangliosides, 0.5 mg/kg vitamin B1, and 1 mg/kg vitamin B6, physiological solution, and controls without any treatment. The recovery from neuropathy was controlled for 18 weeks of treatment and assessed periodically by means of clinical, electromyographic, and morphological examination. The results of morphological studies showed more pronounced regeneration activity in the rats treated with the high dose of gangliosides than in all others, while no differences among the groups could be observed as far as clinical and neurophysiological parameters are concerned. The mechanism supporting this ganglioside-induced effect has so far not been ascertained, and further studies on this subject are in progress.

Animals↗
PubMed1980

[Erythrocyte membrane in Duchenne muscular dystrophy. II. Fluidity of lipids in dystrophic patients and their families].

Electron spin resonance techniques was used to study the fluidity of intact and hemoglobin free erythrocyte membranes from patients with Duchenne muscular distrophy and from members of their family. A greater mobility of spin label motion was observed only at the surface of hemoglobin free membranes in the patients. These studies suggest alterations in lipid-protein interaction, indicating in Duchenne muscular distrophy a generalized membrane abnormality.

Electron Spin Resonance Spectroscopy↗
PubMed1980

[Erythrocyte membrane in Duchenne muscular dystrophy. I. Sensitivity to lysolecithin in dystrophic patients and their families].

The percentage of echinocytes in the blood from patients affected by Duchenne muscular Distrophy was studied after red cells treatment with L-alpha-lysophosphatidylcholine. The echinocyte content was significantly higher in Duchenne patients and in the components of their families, as previously demonstrated is lower in Stainert patients. The sensitivity to lysophosphatidylcholine in Duchenne muscular Distrophy is a diagnostic test for carrier condition

Erythrocyte Membrane↗
PubMed1978

[Partial lipodystrophy and intramembraneous glomerulonephritis].

The case is presented of a young woman with partial lipodystrophy and intramembranous glomerulonephritis. Light and electron microscopic changes in the kidney biopsy are described and discussed. With immunosuppressive therapy very slow progression of the renal insufficiency was observed. Finally, regular dialysis treatment was required to sustain life. The follow-up after detection of intramembranous glomerulonephritis lasted 8 years.

Adult↗
PubMed1978

Electromyographical findings in human chronic Chagas' disease.

An electromyographical investigation of 80 patients with chronic Chagas' disease was made. It was found that 79% of the studied patients had EMG manifestations of old and chronic denervation of the upper and lower limbs without clinical features of nervous system involvement.

Action Potentials↗
PubMed1978

[Bovine graft as arteriovenous fistula for hemodialysis].

We used the bovine carotid artery (BCA) as arteriovenous shunt for hemodialysis in 11 patients since December 1975. We discuss our results. For implantations we used two methods: straight and loop grafts. The BCA have many advantages as: good access for punction, anticoagulation not permanently necessary, volume of shunt more than 250 ml/min; the disadvantages are: increased tendence to infection and thrombosis. Thrombosis in BCA can be easier removed than in other grafts. Reduction of the complications incidence is possible with an accurate technique. We think that the BCA is very useful when Cimino-Brescia fistula has failed or is unavailable; we prefer BCA to a saphenous arteriovenous graft in these situations.

Animals↗
PubMed1977

Metabolism of quaternary carbon compounds: 2,2-dimethylheptane and tertbutylbenzene.

Two Achromobacter strains capable of utilizing 2,2-dimethylheptane or tertbutylbenzene as the sole carbon and energy source were isolated from waste-water. Pivalic acid was found in the cultures of Achromobacter A1 containing 2,2-dimethylheptane. From cultures of Achromobacter A2 in the presence of tertbutylbenzene, a diol was isolated and identified as 2,3-dihydro-2,3-dihydroxytertbutylbenzene. Evidence for meta cleavage of the aromatic ring and for accumulation of pivalic acid in the cultures was also obtained. A metabolic pathway for tertbutylbenzene is suggested.

Alcaligenes↗
PubMed1976

[Peritoneal dialysis, ultrafiltration and hyperosmolarity].

Observation of a patient who developed serious hypernatremia during peritoneal dialysis with a dialysis fluid containing 135 mval Na+/1 prompted investigation of net water, sodium, potassium and chloride transport during 45 peritoneal fluid exchanges with standard dialysis solutions containing 1.5 and 4.5 g% glucose. With both solutions and an equilibration time of 0 min, net ultrafiltration was observed (89 ml and 230 ml per exchange respectively). In both groups the calculated sodium concentration of the ultrafiltrate was considerably lower than plasma sodium concentrations (27.0 mval/1 and 36.9 mval/1 respectively, resulting in a new sieving coefficient of 0.20 and 0.27 respectively. Therefore, the free water deficit resulting from peritoneal ultrafiltration is directly responsible for the hypernatremia observed during peritoneal dislysis. While the potassium and chloride transport observed in these studies can be explained by diffusion processes along a given concentration gradient, sodium transport and sodium concentrations raise the question of more complex mechanisms. The data are discussed with reference to the relative significance of diffusion processes versus bulk flow and solvent drag.

Biological Transport↗
PubMed1976

An electrophysiological investigation of skeletal muscles in polymyositis.

An electrophysiological study has been made of the extensor digitorum brevis, thenar and hypothenar muscles in 25 patients with chronic and acute polymyositis. It was found a reduction of the number of functioning motor units in some patients with chronic polymyositis and only in one of those affected by acute polymyositis and only in one of those affected by acute polymyositis. The sizes of the surviving units suggested that the results could be explained in terms of a primary muscle involvement mainly in acute polymyositis, while in chronic polymyositis a combination of primary and neurogenic involvement of muscle fibers might take place.

Acute Disease↗
PubMed1975

Hypotensive effect of oxprenolol in mild to moderate hypertension: a multicentre controlled study.

In a multicentre, double-blind, between-patient study the hypotensive effect of oxprenolol was investigated in 329 patients with mild to moderate hypertension. A factorial experimental design with three factors was chosen: oxprenolol--none or daily doses of 20, 40, 60 and 80 mg; dihydralazine and hydrochlorothiazide, respectively, none or 30 mg daily. Each treatment was given for 4 weeks after an adequate period of withdrawal from any other possible hypotensive therapy and one week of placebo wash-out. Irresponsive of the association with dihydralazine and/or hydrochlorothiazide, oxprenolol had a hypotensive effect linearly related to dose for standing systolic (P less than 0.05) and diastolic (P less than 0.01) pressure, and for lying diastolic (P less than 0.05) pressure. The additional of dihydralazine enhanced the time-course of the hypotensive effect of oxprenolol, particularly the 80 mg dose level. In general, the combination of oxprenolol with dihydralazine and hydrochlorothiazide caused larger reductions in blood pressure, particularly with oxprenolol 80 mg. In the latter group, the eventual falls in blood pressure were 30.5 and 14.4 mmHg for lying systolic and diastolic, respectively; and 32.1 and 20.0 mmHg for the standing systolic and diastolic pressures. The drug was well tolerated; major side effects (heart failure and bronchospasm) occurred in three patients.

Clinical Trials as Topic↗