1. Five healthy male subjects were studied by continuous infusion of L-[alpha-15N]lysine over 20-30 h with timed blood and urine samples, and two or three percutaneous needle biopsies of vastus lateralis muscle. 2. A standard creatine-free diet, quantitatively related to body surface area, was given for 5 days before the infusion. The [15N]lysine was administered at a constant rate in an amino acid solution with a nitrogen content of 0-96 mol/l, which constituted the sole source of exogenous nitrogen during the infusion. 3. A plateau level of plasma free [15N]lysine enrichment was achieved after infusion for 14 h. The total plasma lysine flux calculated from the plateau was 7-3 mmol/h (range 4-8-9-6). Total body protein turnover calculated from the lysine flux was 3-5 g day-1 kg body wt.-1 (range 2-5-5-0). 4. Muscle sarcoplasmic and myofibrillar fractions were separated, purified and the 15N enrichment was measured. The sarcoplasmic protein fractional synthetic rate was calculated as 3-8%/day (range 2-2-5-1). The myofibrillar protein synthetic rate was 1-46%/day (range 1-09-2-44). 5. Muscle mass, calculated from 24 h creatinine excretion, was 33-7 kg (range 28-8-37-4), which represented 50-0% of body weight (range 38-9-58-1). Total muscle protein synthesis was calculated to account for 53-2% (range 39-5-62-1) of total body protein syntehsis. 6. The advantages and limitations of using continuous infusion of [15N]lysine in human subjects are discussed.

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A case of type 1 (adult) Gaucher's disease with a late onset tapeto-retinal degeneration and an initially dopamine responsive extrapyramidal syndrome is described. The literature reporting neurological involvement in type 1 Gaucher's disease is reviewed, and it is concluded that the absence of symptoms and signs of nervous system involvement cannot be used as the sole basis for the classification of this type of Gauchers disease.

Ten patients with varying degrees of hypothroid myopathy were studied clinically and by serial percutaneous needle muscle biopsies before and during treatment with L-thyroxine. The biochemical evidence of hypothyroidism was related to the severity of the myopathic and signs before treatment. The severity of myopathic symptoms before and during treatment correlated with the biochemical evidence of hypothyrodism, a type II fibre atrophy and increased central nuclear counts. Likewise, the clinical evidence of a myopathy before and during treatment was correlated with both a type II fibre atrophy and loss and increased central nuclear counts but was not related to the biochemical parameters of hypothyroidism, except the level of thyroid stimulating hormone. In the muscle, before and during treatment, of the two most severely affected patients, intracellular glycogen inclusions were seen in scattered muscle fibres. On light microscopy and on electronmicroscopy, numerous mitochondria were seen responding to L-thyroxine with accumulations of subsarcolemmal honey-combing. Vesicular abnormalities, an electron dense matrix or occasional crystalline deposits were seen in muscle mitochondria from less severely azffected patients. Severely myopathic muscle contained excessive glycogen, membrane bound glycogen and excess lipid in a mainly perinuclear distribution. Occasional myelin and membranous bodies were seen and satellite cells during the recovery phase. A group of patients with hypothyroid myopathy who are likely to have a delayed recovery of full muscle strength on L-thyroxine may be recognised by the presence of severe proximal muscle weakness and characteristic changes on histochemical and electronmicroscopic examination of muscle. The spectrum of histochemical and electronmicroscopic abnormalities of muscle revealed with increasing degree of hypothyrodism, suggests that a generally reversible acquired glycogen storage and mictochondrial disorder is an important feature in the pathogenesis of this condition.

A survey of multiple sclerosis in the London Borough of Sutton, population 169 600, yielded 195 cases, giving an overall prevalence of 115/100 000. This is the third highest prevalence for a first survey of a geographical area in the United Kingdom, exceeded only by 127/100 000 in north east Scotland and 134/100 000 in Shetland. On the classification system of Allison and Millar, three quarters of the cases were classified as probable multiple sclerosis, 15% as early probable and latent multiple sclerosis, and 10% as possible multiple sclerosis. The mean age was 49 years, the mean age at onset was 34 years, and the mean duration of the disease was 15-4 years. The age standardised female to male ratio was 2:1.The prevalence found in this survey does not differ significantly from that recorded in the first north east Scotland survey.This study suggests that, firstly, the prevalence of multiple sclerosis in south east England is probably about 100/100 000 and, secondly, the latitudinal effect on the prevalence of multiple sclerosis in the United Kingdom is less appreciable than previously believed.

SUM MARY Myofibrillar protein catabolic rate was calculated in seven patients with Duchenne muscular dystrophy from the amount of 3-methylhistidine excreted in the urine, and found to be over three times that found in a control series when expressed as the percentage (Ionasescu, 1975) have demonstrated abnormalities of protein synthesis in Duchenne muscular dystrophy, with high rates of synthesis of collagen, and low rates of non-collagen protein synthesis in the polyribosomes isolated from patients' muscles. A similar increased polyribosomal protein synthesis was found in the carriers for the X-linked gene (lonasescu et al., 1971; lonasescu et al., 1973

A review of the United Kingdom (UK) multiple sclerosis (MS) literature suggests that over the last three decades prevalence and estimated incidence rates have increased, while mortality rates have been declining. UK mortality data over a 30 year period have been studied to examine temporal and geographical variations, to estimate changes in survival, and to examine the relationship between mortality and morbidity trends. The study has shown an overall decline in mortality throughout the UK of approximately 25% over the 30 year period ending in 1983, and a reduction in the mortality differential between Scotland, and England and Wales, but no positive correlation has been found between mortality and morbidity. The overall decline in death rate in females was 23% and in males 30% over the 30 years of the survey. The total number of deaths declined by 39% between the five year periods 1954-58 and 1979-83 in Scotland compared with a 10% decline for England and Wales. Estimated median age of death increased from 52 to 59 years and the improvement in survival over the period of study was similar for both countries and is unlikely to have contributed to the reduction in mortality differential.Within England and Wales regional mortality rates did not show a clear north-south gradient. The decline in the mortality differential between Scotland and England (if not artefactual) may provide an important aetiological clue in the search for the cause of multiple sclerosis, and the rate of decline suggests an environmental rather than a genetic aetiology.