To show liver failure mediated by 5-aminolevulinic acid (ALA), a heme precursor accumulated in inborn and acquired porphyrias, rats were treated with succinylacetone methyl ester (SAME). Treated rats underwent the expected ALA accumulation in plasma, liver and urine as a result from inhibition of ALA dehydratase (ALAD) activity. The enzyme activity decreased concomitantly with diminished urinary coproporphyrin levels. Additionally, liver protein carbonyls, iron and ferritin were higher in groups treated with a lower concentration of SAME whereas malondialdehyde was higher in the group treated with a higher ester dose. Consistent with these biochemical data, chronic treatment SAME was associated with induced oxidative subcellular and tissue damage revealed by cytosolic and mitochondrial changes within the liver cells. Altogether, these data expand the understanding of the direct biochemical mechanism for liver cell death in hepatic inborn disorders by generating excess ALA and may foster future therapeutic-driven strategies to preserve liver function.

Estudamos um paciente com quadro clínico rebelde, produzido por intoxicação pelo Parathion. Foi observado um fenômeno miotônico transitório, não descrito na literatura revisada. A constatação de cifras de AchE eritrocitária baixas e de colinesterase plasmática normais, indicou que era portador de déficit congênito de AchE, esclarecendo-se a evolução crônica do seu quadro. O fenômeno miotônico associado ao quadro clínico, eletrofisiológico, histológico e bioquímico fazem deste paciente um modelo clínico, de etiologia conhecida, da discutida síndrome de Isaacs.

A case of 38 year old man who worked with organochlorinated and Parathion during 5 years is reported. His follow-up was up to 2 years. The onset of the disease was characterized by cholinergic signs, headache, loss of weight, trembling, miokimias, fasciculations, ataxia, myotonic phenomena (in hands only) and motor sensitive peripheral polyneuropathy (affecting the lower limbs symmetrically). Low concentrations of blood cholinesterases confirmed the etiology. Myotonic phenomena disappeared spontaneuosly 6 months after the initial observation. One year later, the concentration of erytrocyte acetilcholinesterase was found to be low and plasma cholinesterase was normal, suggesting that the patient was carrier of a congenital deficiency of acetilcholinesterase. in literature relationship between myotonia and intoxication due to organophosphorus was not found. The whole clinical picture, cholinergic symptoms, transitory myotonic phenomena and spontaneous motor activity could be explained by an excess of acetilcholine. Eletromyography (EMG) in the first observation showed neuromuscular transmission blocking characterized by deficiency or absence of voluntary activity, unexcitability of fibular nerves, with fibrilations and positive peaks as described previously with Mipafox (another organophosphorus agent). During 2 years of observation numerous end-plates potentials of muscular fibres persisted in the EMG. A progressive increase in voluntary activity showed by unit motor potential of almost normal amplitude and very increased duration was observed. No potentials of reinnervation were noted. The results of EMG were explained as disturbances of neuromuscular transmission associated with moderate signs of denervation The Eaton-Lambert's test and the stimulation of a single unit motor potential confirmed disorder of neuromuscular synapses. The histochemistry of brachial biceps showed scattered atrophic and angulated type I and II fibres. Teased-fibres preparations showed nerve fibres with B, C, and G alterations as defined by Dyck et al. indicating axonal degeneration. These results were according to velocity of sensitive conduction. The conduction velocity of fibular nerves was strongly delayed during all the evolution indicating serious disorders of motor nerves myelin. We think that intoxication by organophosphorus should not be expressed as an identical alteration of both motor and sensitive nerves. The association of myotonic phenomena with such clinical, electrophysiological and histological picture is characteristic of the Isaac's syndrome model with known etiology.

São apresentados os resultados dos exames clínicos, eletrofisiológicos e do estudo do ponto motor, da imunofluorescência, da histoquímica e da ultrami-croscopia da biópsia muscular de um caso de miopatia miotubular. São discutidos estes resultados em relação aos achados de 56 casos desta moléstia consignados na literatura até 1978, sendo dada enfase à etiopatogenia.

A case of myotubular myopathy in a 10 years old girl is reported. Clinically, palpebral ptosis, ocular movements limitation, facial diplegia, posi-tivity of Gower's test, muscular hypotrophy distal, foot drop and deep absent reflexes were found. These signals were described by most of authors, besides symptoms referred, like partial urinary incontinency and frequent vomits. Reflexes H absents and teary in our patient were observed but were not described in the other cases of the literature. Routine laboratory tests were within normal limits; only aldolase was lightly elevated. In all muscles examinated it was noted a spontaneous electromyographic activity with +- of 2,64 ± 1,33 ms, 36,87 ± 30,87 µV and 88,13 ± 24,82 /s of frequency without characteristics of desenervation potentials of myoneural plates. The voluntary electromyographic activity was of myopathic pattern. A curve I/D made in the motor point of braquial biceps muscle was normal. The biopsy was made in the motor point of this muscle for histochemical, electron, immunofluorescence and vital stain microscopy. The biopsy showed 35% of fibras with central nuclei, predominance and hypotrophy of type I fibres, in some of them there were not myofibrils in the central zone, and poor differentiation between the fibre types in oxidative enzymes reactions. The electron microscopy confirmed the histochemical studies. The direct immunofluorescence was positive in some fibres. The vital stain showed beaded subterminal motor fibres. The clinical, electromyographic and principally histological findings suggest a innervation congenital disorder of muscle fibres.

É relatado um caso de doença de McArdle em paciente do sexo masculino, que apresentava cãimbras relacionadas a exercícios físicos e emissão de urina vermelha. A falta de elevação da taxa do lactato venoso após exercício físico em condições anaeróbicas, aliada à histoquímica do músculo, comprovaram o diagnóstico.

This disease was described by McArdle as an inherited autosomal recessive affection characterized by glicogen storage with normal chain in the skeletal muscles, due to absence of myophosphorylase activity. Under a clinical aspect, excessive fatigability, cramps and myoglobinuria appear following physical exercise. A case of this disease in a 36-year-old male patient is reported. Failure of elevation of venous blood lactate after physical effort under anaerobic conditions, as well as muscle histochemistry, made diagnosis confirmation possible. The authors comment on the differential diagnosis betwen McArdle's disease and the other causes of myoglobinuria, specially phosphofructokinase and carnitine-palmityl-transferase deficiency.