A.E.F.H. Meijer

Familial carnitine deficiency. A fatal case and subclinical state in a sister.

A 15-year-old girl with a large accumulation of lipid in the muscle fibers, was suffering from systemic carnitine deficiency. She died in acidosis. The blood carnitine level was normal. At necropsy, carnitine levels were low in skeletal muscles and heart, whilst a normal level was found in the liver. Carnitine palmitoyltransferase II and palmitoyl-CoA synthetase activities were increased, whereas carnitine acetyltransferase, glycerol-3-phosphate dehydrogenase (FAD) and succinate dehydrogenase were decreased. Investigation of blood and skeletal muscle of the family members revealed marked abnormalities in a 7-year old sister who had only minor neurological symptoms. Histochemical investigation revealed abnormal accumulations of lipid between the myofibrils. Carnitine was decreased in her skeletal muscle and blood. Muscular carnitine palmitoyltransferase II and palmitoyl-CoA synthetase were again increased in activity while glycerol-3-phosphate dehydrogenase (FAD) was decreased. The activities of succinate dehydrogenase, carnitine palmitoyltransferase I and glycerol-3-phosphate dehydrogenase (NAD+) were normal. The unexpected normal carnitine level in blood and liver of the deceased patient was attributed to muscle wasting, which was confirmed by the very high blood level of creatine phosphokinase. This fatal case indicates that the fasting condition must be avoided in persons with carnitine deficiency. In crises, glucose supply is necessary since gluconeogenesis may be blocked.

Observations on central core disease

Abstract A description is given of 2 patients who had cores in their muscle fibres. Patient 1 was a 5-year-old girl suffering from a non-progressive myopathy mainly involving the pelvic girdle. Histochemical investigation of the muscle tissue did not permit a differentiation into type I and type II fibres. Cores were present in 10% of the muscle fibres. Patient 2 was a 12-year-old boy suffering from a severely progressive myopathy. The first manifestation of the disease was facial diplegia. Cores were found in 10% of the type I fibres. The father and mother of both patients showed myopathic features on electromyographic examination.

Mitochondria with defective respiratory control of oxidative phosphorylation isolated from muscle tissues of thyroidectomized rabbits

Abstract The effects of thyroidectomy on different muscles of female rabbits were investigated. The histopathological alterations were not equally pronounced in different muscles. The m. soleus revealed only very slight alterations, m. gastrocnemius, m. biceps and m. triceps slight alterations, and m. psoas, the diaphragm and the long dorsal muscle prominent morphological alterations. In the severely-affected muscles the histopathological changes were reminiscent of muscular dystrophy. Biochemical studies showed that following thyroidectomy there was a relative increase in mitochondria with loosely-coupled oxidative phosphorylation, particularly in severely-damaged muscles. The decrease of the respiratory control index was highly significant for 3 of the 4 muscles studied.

Alteration of the maximal activity of the gluconeogenetic enzyme fructose-1,6-diphosphatase of skeletal muscle by cross-reinnervation

Fatiguability is a determining characteristic of different muscle fibre types. An important aspect, indirectly related to fatiguability, gluconeogenesis, was investigated by observing fructose-1,6-diphosphatase (FDP) activity in experimental models prepared in rabbits by cross-reinnervation of the fatigue-resistant m.soleus (postural muscle) and the highly fatiguable m.flexor digitorum longus (fast muscle -- m.fdl). The resultant reprogramming of the m. soleus was associated with greatly intensified FDP activity. Changes in the m.fdl 6-9 months after cross-reinnervation indicated a shift in the opposite direction. The study adds some data on the much neglected state of fatiguability to the otherwise much explored field of alien reinnervation.

Fibre hybrids in type group: An investigation of human muscle biopsies

Change of fibre type caused by reinnervation implies change in a series of metabolic processes. As long as these changes are in progress the histochemical pattern in muscle fibres may demonstrate deviations from the normal characteristics. The present histochemical study was undertaken to evaluate in human neurogenic muscle disease the completeness of conversion of presumably reinnervated muscle fibres. n nAt least a number of muscle fibres in type groups is reinnervated. Type grouping of non-atrophic fibres was found in 27 of 42 muscle biopsies from patients with denervating diseases. The myosin ATPase activity in these groups was often strikingly even. In a varying degree and in a varying number of muscle fibres myosin ATPase-uniform groups showed intermediate capacity of aerobic and/or glycolytic metabolism; this finding was considered compatible with conversion due to reinnervation. Two main kinds of fibre hybrids were observed. One kind showed low myosin ATPase activity and an apparently low capacity for aerobic metabolism. The other kind also showed low myosin ATPase activity but the capacity of glycolytic metabolism was high, aerobic metabolism in these fibres being intermediate or high. n nIt has been suggested that low capacity of aerobic metabolism in fibre hybrids of the first kind is related to hypertrophy of the muscle fibres. The appearance of fibre hybrids of the second kind would be conceivable as a stage in a process of conversion, if at least changes in the capacities of the 2 metabolic pathways can develop at a markedly different pace. However, groups or fascicles of fibre hybrids of this kind are present is some cases. These configurations point to a steady state rather than to a dynamic process of conversion; a lack of plasticity in the muscle fibre apparently prevents completion of conversion.

Histochemical features of tubular aggregates in diseased human skeletal muscle fibres

This communication presents the results obtained in tubular aggregates of 24 enzyme histochemical techniques for demonstrating activity of oxidoreductases, transferases, hydrolases and isomerases. The activity characteristics of the tubular aggregates in m. gluteus medius of 18 patients with diseases of the neuromuscular system were almost identical. A high activity of the mitochondrial enzymes, NADPH: tetrazolium oxidoreductase, NADH:tetrazolium oxidoreductase and cytochrome c oxidase, could be shown in the pathological structures, whereas the activity of the mitochondrial enzymes, glycerol-3-phosphate:menadione oxidoreductase, succinate:PMS oxidoreductase, malate:NAD+ oxidoreductase and isocitrate:NAD+ oxidoreductase, and the partial mitochondrial enzymes, malate:NADP+ oxidoreductase and isocitrate:NADP+ oxidoreductase, was very slight or even absent. There was a moderate to strong activity of the glycolytic enzymes lactate:NAD+ oxidoreductase, glyceraldehyde-3-phosphate:NAD+ oxidoreductase, phosphofructokinase, phosphoglucomutase and glucose phosphate isomerase. In contrast, the activity of alpha-glucan phosphorylase was slight. The activity of phosphogluconate:NADP+ oxidoreductase, glucose-6-phosphate:NADP+ oxidoreductase and 5-nucleotidase was slight, whereas there was no activity of myosin ATPase and mitochondrial ATPase, acid phosphatase or alkaline phosphatase. The high activity of AMP-deaminase was very striking. The activity of peroxidase was moderate. Results obtained with adsorption studies point to adsorption of some of the enzymes studied to the tubular aggregates in vivo and this phenomenon very probably determined the histochemical characteristics of these structures.

A dystrophy-like myopathy in thyroidectomized rabbits

Abstract The histopathological and enzyme histochemical changes in the muscles of thyroidectomized rabbits are described. Between 4 and 18 months after thyroidectomy, the muscles were found to show changes reminiscent of muscular dystrophy, e.g. marked variation in fibre diameter, rounding of fibres, central migration of nuclei, vesicular nuclei with prominent nucleoli, sarcoplasmic masses and, in the later stages, a marked increase in connective tissue and a moderate increase in adipose tissue. Enzyme histochemical changes were also significant, both with oxidative and with glycogenolytic enzymes. Sarcoplasmic masses have been produced experimentally in the muscles of thyroidectomized rabbits.

Myopathy of the quadriceps muscles

Abstract A description is given of 2 brothers, aged 34 and 38 years respectively, who were both suffering from a very slowly progressive paresis and atrophy of the quadriceps muscles, with EMG changes indicative of a myopathy. Although the other muscles showed no signs of paresis, electromyographic examination did disclose myopathic changes elsewhere. Both patients showed creatinuria and increased serum creatine-phosphokinase activity. The muscle biopsy disclosed a variation in the diameter of muscle fibres, with increased fat and connective tissue and many ringed fibres and sarcoplasmic masses. The disease was interpreted as being a special form of muscular dystrophy.

Follow-up study of a myopathy with loosely coupled mitochondria.

This communication deals with a clinical, histological, histochemical and biochemical follow-up study of a boy with an ameliorating myopathy with loosely coupled mitochondria who was studied earlier. In the course of about 15 years the clinical condition of the patient improved greatly. In a biopsy of skeletal muscle the same pathological features were found as before, but the pathological changes were much less severe. In contrast to earlier findings, the majority of the fibres with a loosely coupled state of the mitochondria belonged to the anaerobic type II fibres.

Elevated activity of several antioxidant enzymes in neuromuscular diseases: A Histochemical and Biochemical Study

In the present study the activity of glucose-6-phosphate dehydrogenase, phosphogluconate dehydrogenase, glutathione peroxidase, glutathione reductase, superoxide dismutase and catalase was measured in dissected specimens from muscle biopsies of patients with various neuromuscular diseases and from controls. The biopsy specimens investigated were selected by means of histological and enzyme histochemical staining methods. Specimens were used which contained muscle fibres with a high or low activity of glucose-6-phosphate dehydrogenase and phosphogluconate dehydrogenase and which were free from inflammatory infiltrates. A rise in activity of glucose-6-phosphate dehydrogenase in pathologically changed muscle fibres was always found to be coupled with a significant rise in activity of phosphogluconate dehydrogenase, glutathione peroxidase and glutathione reductase. In these muscle fibres the activity of superoxide dismutase and catalase was not significantly changed. On the basis of the histochemical and biochemical findings it is concluded that the application of the histochemical method for the demonstration of glucose-6-phosphate dehydrogenase activity can be highly recommended for the study of antioxidant enzymes in skeletal muscles with neuromuscular diseases.