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Biomedical subjects

J C Waterlow

Publications and source records attributed to J C Waterlow.

At least 91 records · Page 5Linked to original sources
PubMed1980

The effect of rehabilitation at different stages of development of rats marginally malnourished for ten to twelve generations.

1. Rats which have been maintained for ten to twelve generations on diets of low protein value were rehabilitated in utero (group P), from birth (group F) and from 4 weeks of age (group W). 2. Group W showed little change in physique, behaviour or learning, indicating that for recovery to be effective refeeding must begin earlier. 3. Group F just failed to attain full physical recovery (90%) whereas group P overgrew by 18.6% in weight and 8.5% in length. 4. In a test designed to evaluate learning ability rehabilitated rats of groups P and F were significantly less successful than normal rats, but more successful than rats of group W or rats of the original undernourished colony. 5. Rehabilitation for a further two generations in groups F and P corrected any residual physical and behavioural defects but produced no further improvement on the Lashley (1938) jumping platform.

Acoustic Stimulation↗
PubMed1980

Diurnal pattern of protein and energy metabolism in man.

Rates of synthesis and breakdown of body protein and oxidation of leucine were measured in six obese subjects by constant intravenous infusion of (1 14C)leucine for 24-hr periods. During the night, when no food was given, the rate of whole body protein synthesis was 67% of the rate observed furing the day, when food was given hourly. By contrast the rate of body protein breakdown remained constant over the full 24 hr. This resulted in the immediate deposition of about 30% of the protein intake during the day, whereas the remaining 70% was immediately oxidized. At night the rate of protein oxidation fell to only 38% of its daytime value. The rate of oxygen consumption also decreased at this time so that the contributon of protein oxidation to total energy expenditure fell from 27% during the day to 13% at night. These changes reflect the normal, discontinuous pattern of food intake and the need during feeding to store protein in tissues for use in subsequent periods of fasting.

Circadian Rhythm↗
PubMed1980

Influence of low-energy diets on whole-body protein turnover in obese subjects.

Rates of whole-body protein synthesis and breakdown in obese subjects have been measured by three methods: constant intravenous infusion of [1-14C]leucine, repeated oral doses of [15N]glycine, and a single oral dose of [15N]glycine. The three techniques gave similar rates of synthesis and breakdown when the subjects received a normal diet containing 8.0 MJ and 70 g protein. After 3 wk on a low-energy diet (2.1 MJ), repeat measurements were made. When the low-energy diet contained protein (50 g), rates of protein synthesis and breakdown were little different from those with the normal diet. When the low-energy diet contained no protein, there was a 40% fall in whole-body protein synthesis and a smaller fall in breakdown. Excretion of 3-methylhistidine in the urine did not change with either low-energy diet. We conclude that the decrease in dietary energy from 8.0 to 2.1 MJ did not influence protein turnover, but that dietary protein was necessary if rates of whole-body protein synthesis and breakdown were to be maintained.

Adult↗
PubMed1979

Observations on the adequacy of breast-feeding.

The faltering of growth which frequently occurs in babies at the age of about 3 months in developing countries is sometimes attributed to insufficient food or to increased exposure to infection. The adequacy of breast-milk as a sole source of food for the young infant is examined in relation to the calculated average requirements for protein and energy. It is concluded that breast milk will fail to cover the energy needs of many infants after about 3 months unless a regulatory mechanism permits infants with higher than average requirements to obtain larger amounts of milk.

Age Factors↗
PubMed1979

Changes in content and composition of brain phospholipids in malnourished children.

The content and composition of phospholipids were studied in the brain of children who died from severe malnutrition within the first 2 years of life, and compared with those obtained from well-nourished children who died of accidents, or of illnesses not known to affect the central nervous system. Each brain was separated into the constituent major parts--the forebrain, brain stem, and the cerebellum. With the exception of a few marasmic children under 1 year of age whose forebrain and cerebellum had higher phospholipid concentration than normal, the concentration of the lipids on dry weight basis in all brain regions of the malnourished children was the same, regardless of age, as that in the children who were normal nutritionally. However, the phospholipid:DNA ratio in the forebrain and the cerebellum of most of the malnourished children under 1 year of age was higher than normal. The brain stem of only a few malnourished children aged around 1 year also had higher phospholipid:DNA ratio than normal. Among the different phospholipids, sphingomyelin was found to be selectively decreased in each brain part of the malnourished children aged 1 year or more.

Brain↗
PubMed1978

Protein turnover in man measured with 15N: comparison of end products and dose regimes.

Whole-body protein synthesis was measured with [15N]glycine in malnourished and recovered infants and in obese patients. Comparisons were made: 1) between results obtained with single (S) and repeated (R) oral dosage of tracer; and 2) between urea and ammonia as end products. In the infants S and R gave similar values for the synthesis rate. With both methods of dosage, the values obtained with NH3 as end product were about two-thirds of those with urea. It is suggested that the cause of this result is that glycine contributes preferentially to the formation of urinary NH3. With NH3 as end product, a collection period of 12 h has been found to be suitable. With urea it is not possible to define an appropriate collection period. The combination of single dose of [15N]glycine with urinary NH3 as end product provides a simple method for measuring whole-body protein synthesis under clinical and field conditions. It can be repeated at short intervals and can give useful comparative information provided that conditions are carefully standardized. The reproducibility so far is +/- 13%.

Adult↗
PubMed1977

Protein turnover in patients before and after elective orthopaedic operations.

Whole body protein turnover was measured in 11 patients before and after elective orthopaedic operations be giving 15N-glycine orally every 4 hours for 32 hours. The patients were maintained throughout on a constant protein intake. In 2 control subjects a comparison was made between intermittent dosage and continuous infusion of 15N-glycine for the estimation of total protein turnover. With intermittent dosage the 15N abundance in urinary urea reached a constant level after about 24 hours. Rates of total protein synthesis and breakdown were calculated from the 15N abundance at the plateau level. After surgery there was a moderate increase in urinary N output. The apparent N balance (intake--urinary N) was -0-52 +/- 1-31 g/d (mean +/- s.d.) before operation and -7-51 +/- 4-5 g/d after operation. The rate of protein synthesis fell from 3-83 +/- 0-73 g kg-1 d-1 before operation to 2-94 +/- 0-83 g kg-1 d-1 after operation. This difference is statistically significant (0-05 greater than P greater than 0-01). There was no significant change in the rate of protein breakdown. The possibility remains that a block in protein synthesis, probably mainly in muscle, may be partly responsible for the so-called 'catabolic' loss of nitrogen after injury, but this has not been proved.

Adult↗
PubMed1977

Protein turnover, synthesis and breakdown before and after recovery from protein-energy malnutrition.

1. Rates of total protein turnover, synthesis and breakdown were measured in five children before and after recovery from severe protein-energy malnutrition and while receiving 0.6 g of protein and 397 kJ day-1 kg-1. 2. Thes rates were calculated after giving doses of [15N]glycine every 2 h along with the feeds and measuring the rate of excretion of [15N]urea in urine. 3. Malnourished children had significantly lower rates of protein turnover, synthesis and breakdown than after they had recovered. 4. During recovery from protein-energy malnutrition, two children on a daily intake of 1.2 g of protein and 605 J/kg body weight, had rates of protein turnover, synthesis and breakdown that were twice as great as those found on admission and higher than after recovery. 5. On the study diet the malnourished children maintained their weight while the recovered children lost weight; the apparent nitrogen balance was more positive in the malnourished children. 6. In recovered children, the rate of protein synthesis was unchanged over a wide range of protein intake, whereas the rate of protein breakdown appeared to rise with a reduction in protein intake.

Body Weight↗
PubMed1977

Endogenous loss of leucine and methionine in adult male rats.

1. The fractional rate of loss of 14C and body-weight was measured in adult male rats after giving 14C-labelled methionine or leucine and maintaining rats for 30 d on a low-protein or a specific methionine+cystine-free diet: carcasses were then analysed for protein and fat 14C radioactivity. 2. The fractional loss of 14CO2 from [14C]methionine or [14C]leucine between day 20 and day 30 was always greater than the fractional loss of body-weight. 3. Carcass protein 14C radioactivity after giving [14C]leucine was higher than after giving [14C]methionine, but fat 14C radioactivity after either 14C-labelled amino acid was only a small proportion of the total body 14C radioactivity. 4. After correction of the fractional loss of 14CO2 for urinary 14C loss, but not body-weight loss, absolute amino acid loss was calculated using published values for methionine and leucine content of rats. 5. The best estimates of endogenous amino acid loss obtained using I-14C-labelled amino acids, expressed as mg/kg body-weight 0.75 per day were leucine 79, methionine 38.

Animals↗