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.

No abstract

No abstract

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.