1. A method is described enabling the determination of fat, water, electrolytes, protein, DNA, RNA and total creatine in a single sample of human muscle obtained by the percutaneous needle-biopsy technique. The amino acid content can also be analysed in the same muscle sample. 2. Fifty healthy subjects were studied: 29 between 19 and 40 years of age, 11 between 41 and 60 years of age, and 10 between 61 and 85 years of age. The two groups aged less than 60 years showed only marginal differences in muscle composition, whereas the highest age group showed increases in muscle fat content in relation to tissue weight and decreases in alkali-soluble protein content in relation to both tissue weight and tissue DNA content. Also, potassium, magnesium, total creatine and RNA contents were decreased in this age group when related to tissue DNA content. When alkali-soluble protein was used as a reference base, only magnesium content was decreased. 3. A comparison was also made between female ( n = 23) and male ( n = 18) subjects in the age groups below 60 years. Differences observed included a higher fat content in female muscle, and an increase in total creatine content in relation to tissue weight. The alkali-soluble protein content was lower per muscle cell in the females when calculated on the basis of DNA content. 4. The results show that in the assessment of muscle constituents, age and sex must be taken into account.

1. To determine the possible role of arterial cyclic AMP in the pathogenesis of hypertensive vascular hypertrophy and hyperplasia, the changes in the level of this nucleotide were studied during the development of renal hypertension in rats with aortic ligation between the renal arteries. 2. A twofold increase in the cyclic AMP level of the thoracic aorta was observed in 9-day hypertensive rats when compared with sham-operated controls. At this time the total amounts of DNA and collagen were unchanged, although a marked increase in arterial fibrous protein was already present. 3. Arterial cyclic AMP remained significantly elevated in the thoracic aorta of 30-day hypertensive animals. At this time the hypertensive vascular alterations had reached completion as shown by the abnormal accumulation of collagen, DNA and non-fibrous protein. 4. Contrary to the events taking place in the thoracic aorta, a marked decrease in cyclic AMP was present in the abdominal portion, which was protected from high blood pressure by the aortic ligature. in this segment decreased cyclic AMP coexisted with an unchanged collagen content and a diminution in the contents of DNA and non-fibrous protein. 5. Thus a marked increase in arterial cyclic AMP precedes the initiation of DNA replication and collagen accumulation in vascular territories subjected to high blood pressure. These studies suggest the participation of this nucleotide in the vascular growth induced by hypertension.

1. Water absorption rates by small intestine in vitro and the incidence of diarrhoea in vivo were estimated after 5-fluorouracil was injected into rats at various times of day and night. 2. Impairment of water absorption and the incidence of diarrhoea were minimal in rats on a normal dietary regimen when the 5-fluorouracil was injected at around 02.00 hours. 3. the DNA content of the mucosa of the small intestine from uninjected animals also showed a diurnal variation, with a maximum at around 03.00 hours. 4. Manipulation of the time of injections (possibly in relation to feeding time) provides a potential means for increasing the therapeutic value of 5-fluorouracil.

1. Kidney weight and content of protein, RNA and DNA were measured in rats with streptozotocin diabetes of varying duration. 2. Diabetic rats had larger kidneys than control rats: after 3 days of diabetes the weight increase was 15% and after 42 days of diabetes it was 90%. The protein content rose in parallel to the weight. 3. RNA content was already increased after 36 h of glycosuria, whereas DNA content was unchanged for the first 3 days of diabetes, and increased thereafter. The protein/DNA ratio increased rapidly during the first 3 days but remained constant thereafter. 4. Insulin treatment decreased the renal weight gain by about 67% during the first 8 days of diabetes, but did not prevent the increase in DNA. When insulin was started after 25 days of diabetes there was only a slight regression of kidney growth.

1. Rats of four different age groups were injected intraperitoneally with labelled thymidine and killed 1, 7 or 12 days later. 2. The epididymal fat-pads were separated into fat-cells and stromal elements by collagenase digestion. 3. The incorporation of labelled thymidine into the deoxyribonucleic acid (DNA) of both fractions was greatest in the 6-week-old animals. Uptake was significantly decreased in 12- and 15-week-old animals and was lowest in 22-week-old rats.