C. Coërs

Cimetidine Interaction with Carbamazepine

Excerpt To the editor: A recent report of Desmond and colleagues (1) showed delayed clearance of diazepam due to cimetidine. Similar interactions of cimetidine have been mentioned with antipyrine, ...

The early stages of neuromuscular regeneration after crushing the sciatic nerve in the rat. Electrophysiological and histological study

Abstract Crushing of the sciatic nerve was performed on 84 rats and the functional recovery, reinnervation and distribution of fibre types were studied at short intervals between the crush and the 133rd day. The amplitude of evoked muscle potentials increased from the 25th day and regained a normal value after the 42nd day. Evidence of reinnervation of muscle fibres was observed as early as the 14th day. Apparently complete reinnervation was seen in some muscles 33 days after the crush. Type-grouping took place from the 42nd day; it was preceded from the 28th day by a stage characterized by the presence of numerous intermediate fibres. It may be concluded that the delay between reinnervation and functional recovery on the one hand and the occurrence of type grouping of muscle fibres on the other represents the time necessary for the reversal of the enzymatic pattern in muscle fibres being reinnervated by axons different from the original ones. The transitional stage observed between the normal pattern and the type grouping is probably the morphological expression of this evolution.

Familial focal loss of cross striations

SummaryTwo patients, a brother and sister, both suffering from congenital generalized muscle weakness with a progressive course are reported. Muscle biopsy revealed areas with loss of cross striations in the muscle fibers, electronmicroscopically presenting complete disorganization of the myofibrils with streaming of the Z discs and absence of mitochondria. Vesicular nuclei with prominent nucleoli were present in these areas. There was a type I fiber prodominance in both cases. The mean diameter of the type I muscle fibers in one of the cases was too small. Motor endplate alterations in this patient gave no evidence of denervation but were suggestive of a delayed development of motor nerves.ZusammenfassungEs werden zwei Patienten beschrieben, Bruder und Schwester, beide an einer kongenitalen, generalisierten, progressiven Muskelschwäche leidend. Die Muskelbiopsie zeigte Zonen mit Verlust der Querstreifung in den Muskelfasern, und bei elektronenmikroskopischer Untersuchung zeigte sich eine totale Unordnung der Myofibrillen mit Strömung der Z-Scheiben und Fehlen von Mitochondrien. In diesen Bezirken fanden sich blasige Kerne mit prominenten Nukleolen. In beiden Fällen zeigte sich ein starkes Überwiegen der Typ-I-Fasern. Der mittlere Durchmesser der Typ-I-Muskelfasern war in einem der Fälle zu gering. Veränderungen in der motorischen Endplatte in diesem Fall zeigten keine Denervierung, sondern deuteten auf eine verzögerte Entwicklung der motorischen Nerven.

MORPHOLOGICAL AND HISTOCHEMICAL CHANGES OF MOTOR UNITS IN MYASTHENIA

Neuromuscular biopsies were obtained from 45 myasthenic patients. Motor innervation was studied in all specimens by vital staining with methylene blue. Quantitative data included the proportion of elongated motor endings, and the terminal innervation ratio (TIR) of motor axons. Quantitative histochemical data, obtained on 12 biopsies, included the atrophy factors of type I and II fibers, the I/II ratio, and the proportion of fibers strongly reacting to both ATPase and NADH diaphorase (type III fibers). Statistical analysis of the data led to the following conclusions: (1) elongated motor endings, found in 26 biopsies, were not related to denervation or to the severity of the disease, and were preferentially observed in younger patients; (2) increased TIR suggesting denervation was observed in 7 biopsies, only in patients over 50 years; and (3) various histochemical changes were found, mainly numeric reduction of type II fibers, having no demonstrable relationship with the incidence of elongated motor endings. The highest TIR was observed in a biopsy containing an increased proportion of type III and intermediate muscle fibers.

Familial myopathies with restricted distribution, facial weakness and inflammatory changes in affected muscles.

SummaryA myopathy characterized by restricted involvement of few muscles and inflammatory cell infiltration was observed in three families. In the first family, clinical features, hereditary transmission and biopsy findings were consistent with the diagnosis of facioscapulohumeral dystrophy. However in three of the four affected members, the occurrence of atrophies was specifically initiated by severe muscular pain. In the second family two 8-year-old identical twins had both marked facial weakness and atrophy limited to the right quadriceps femoris. In the third family, marked asymmetry of muscular wasting in the upper limbs was found in the 17-year-old daughter of a man suffering from facial and axial weakness. The indication of corticotherapy in such cases is discussed.

The pattern of terminal motor innervation in healthy young adults.

The functional, or true terminal innervation ratio (TIR) was estimated on 13 neuromuscular biopsies taken from 5 palmaris longus and 7 tibialis anterior muscles in 7 male and 6 female healthy young volunteers. Axonal ramification resulting in the innervation of more than 1 muscle fibre by 1 subterminal axon occurs in 10.6% of the total number of axons studied. Most of the branching axons (94%) innervate 2 muscle fibres. Only 5.1 of them supply 3 muscle fibres by trifurcation. Innervation of 4 muscle fibres by 1 ramified subterminal axon is extremely rare and was observed in 0.9% of branching fibres, i.e. in 0.1% of all axons studied. There is no significant difference between the TIR of palmaris longus and that of tibialis anterior, nor between the values obtained in males and females. A mean TIR of 1.12 was obtained (range 1.05–1.20). Statistical analysis indicates that values higher than 1.25 are outside the normal range of distribution.

Terminal motor innervation in myopathic hamsters

Terminal motor innervation and the histochemical profile of muscle fibers were investigated, before and after sciatic nerve crushing, in 1- to 150-day-old myopathic hamsters. The observed morphologic abnormalities in terminal motor innervation were of varying degree prior to the nerve injury. These abnormalities were found in close proximity to lesions of the myofibers, and became more pronounced with age and the progression of the disease process. Collateral ramification of healthy axons occurred in hamsters of 120 days of age with reinnervation of damaged muscle fibers. When submitted to sciatic nerve crushing, myopathic hamsters showed an ability to regenerate and reinnervate the subneural apparatuses. The regenerative process in these animals was essentially the same as in normal, sciatic nerve-crushed hamsters. Thus, it was concluded that the morphologic changes in terminal motor innervation were secondary to muscle cell degeneration.