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Biomedical subjects

N Cameron

Publications and source records attributed to N Cameron.

At least 55 records · Page 3Linked to original sources
PubMed1988

Fast to slow phenotypic changes in rabbit muscle can be induced without increases in neural activity.

Immobilization of rabbit tibialis anterior (fast) muscle in a lengthened position for 5 weeks led to a fivefold increase in the number of slow oxidative fibres. Unlike the situation in other models of phenotypic change in adult muscle, the increased expression of slow phenotype was not associated with an increase in the level of electrical activation, as monitored in the stretched muscles by chronic telemetric electromyography.

Animals↗
PubMed1988

Recovery from immobilization-induced atrophy of rabbit soleus muscles can be accelerated by chronic low-frequency stimulation.

Immobilization of rabbit soleus muscles with an ankle joint angle of 90 degrees led to gross degeneration after 2 weeks. Natural recovery in the subsequent 2 weeks had little effect on the mean area of soleus fibres, although there were signs of regeneration. However chronic low-frequency activation of soleus muscles by nerve stimulation greatly accelerated recovery, producing muscle fibres of normal areas and with characteristics of maturity.

Animals↗
PubMed1986

Standards for human growth--their construction and use.

Human growth charts are used in the RSA to monitor the growth of groups of children and of individuals. Ignorance of their construction leads to misunderstandings of their correct application. The construction and use of growth charts is reviewed by explaining how growth may be investigated through cross-sectional, longitudinal and mixed-longitudinal studies and the problems involved in using the subsequent data. The intellectual confusion brought about by describing such charts as 'standards' and how the most appropriate chart for South Africa should be defined is also discussed. Finally, the priorities for research in this field are outlined.

Adolescent↗
PubMed1986

Timing and magnitude of adolescent growth in height and weight in Cape coloured children after kwashiorkor.

One hundred sixteen patients who had had kwashiorkor between the ages of 5 months and 4 4/12 years and 89 controls were the subjects of a 15-year follow-up study of their growth and development. We report the findings of a longitudinal analysis of 53 (30 females) of the ex-patients and 30 (15 females) of the controls, selected because at the end of 15 years of study they conformed to the criteria of adult secondary sexual characteristics, height velocity less than 2 cm/yr, and completeness of data. Nonlinear curve-fitting techniques were applied to the height and weight data for these subjects using the Preece-Baines model 1 growth function to determine the timing and magnitude of adolescent growth spurts and the associated biologic changes. Both ex-patients and controls grew below the 25th percentile of British longitudinal standards, but the male ex-patients were heavier, and perhaps taller, than the controls for most of their childhood and adolescence. Velocity curves indicated that the ex-patients had higher pre-adolescent peak increments than the controls and a generally longer growth spurt of reduced magnitude. Two possible explanations are discussed: Garrow and Pike's theory that children with kwashiorkor have a genetic potential for greater physical growth, and a socioeconomic crisis occurring within a family affects the youngest child, who subsequently requires a longer time to recover than do siblings within an improving socioeconomic situation.

Black People↗
PubMed1983

Prediction of adult height from height and bone age in childhood. A new system of equations (TW Mark II) based on a sample including very tall and very short children.

A new series of equations is presented for predicting the adult height of a child given present height and bone age. These equations (TW height prediction, Mark II) which replace the ones given in 1975 (TW height prediction, Mark I) are based on larger numbers of normal children, and more importantly on a sample that includes, for the first time, numbers of very tall, very short, and very growth-delayed children. In addition, equations are given for use when the increment of height or bone age, or both, over the previous year is known. These variates improve the prediction at most ages over 8 years in girls and 11 years in boys. The previously given parental allowance has been dropped. Typically 95% of the predictions lie within +/- 8 cm of the real value for boys aged 10 years, falling to +/- 6 cm for boys aged 15 years, or +/- 4 cm if their previous height increment is known. For premenarcheal girls the predictions lie within about +/- 6 cm at age 8 years; a figure which diminishes little till 13 years unless height and bone age increments are known, when it reaches +/- 4 cm at 13 years. For postmenarcheal girls the predictions are substantially more accurate.

Adolescent↗
PubMed1981

Growth hormone treatment in children with craniopharyngioma: final growth status.

Twenty-seven out of thirty craniopharyngioma patients treated with human growth hormone (hGH) for 2 years or more (average 4.5 years) reached final adult heights above the population third centile, though none was above the fiftieth centile. However, only twelve of twenty-eight patients had final heights above the lower limits to be expected from their parents' heights. All patient eventually had long legs relative to sitting height (final mean subischial leg length SDS = + 0.2, final mean sitting height SDS = -3.0). Twenty-nine patients were TSH-deficient, twenty-two were ACTH-deficient, thirteen were deficient in ADH and all had total (85%) or partial (15%) gonadotrophin deficiency. Following the administration of testosterone or hCG the boys had, on average, only half the normal adolescent growth spurt. This may have been due to the lateness of starting androgens in these patients and we recommend, when considering height, that testosterone or hCG should be started when a bone age of 13.0 "years' is reached or when a lower bone age has remained unchanged for a year. The girls showed adolescent height spurt; the average increase after oestrogen treatment commended was 1.7 cm.

Adolescent↗
PubMed1981

Gonadotrophin response to LH-RH in boys with delayed growth and adolescence.

Plasma luteinising hormone (LH) and follicle-stimulating hormone (FSH) concentrations were measured before and after intravenous luteinising hormone-releasing hormone (LH-RH) in 33 boys with growth delay. Eighteen were prepubertal and 15 pubertal. Basal LH and FSH levels were low in both groups with mean increments after LH-RH of 3.2 +/- 0.8 U/l (mean +/- SEM) and 2.6 +/- 0.4 U/l respectively in the prepubertal and 7.4 +/- 0.7 U/l and 2.0 +/- 0.3 U/l in the pubertal boys. The LH increment showed a positive correlation with increasing bone age (r = 0.71, P less than 0.001); FSH did not. The LH-RH response thus appeared normal in relation to the stage of maturity.

Adolescent↗
PubMed1976

Weight and skinfold variation at menarche and the critical body weight hypothesis.

The weight and skinfolds of 36 longitudinally studied British girls were analysed to determine their variability from two years pre-menarche to two years post-menarche. If the critical body weight hypothesis of Frisch and Revelle (1970) is true, a reduction in the variability of these parameters would be expected at menarche compared to times before and after this event. No such reductions in variability were apparent.

Adipose Tissue↗
PubMed1976

Dose dependence of growth response to human growth hormone in growth hormone deficiency.

A trial of the relative effect on growth of 20 IU/week and 10 IU/week of human growth hormone has been made in 38 patients with "isolated" growth hormone deficiency over 1 year of treatment, 18 patients over 2 years and 10 over 3 years, and in 17 patients with surgically treated craniopharyngiomata over 1 year. The velocity of height growth in the first year of treatment, compared with a full year of pre-treatment control, was 1.3 times as great in both groups of patients on the larger dose as it was in those on the smaller one. Second-degree equations fitted to the treatment catch-up curve gave estimates of 1.7 cm more height gained on the larger dose by the end of the first year, 2.7 cm by the end of the second, and 3.4 cm by the end of the third. Adjusting treatment increment by covariance for bone age at the beginning of treatment, pre-treatment velocity, and body surface area did not alter these mean differences. Bone age velocity during treatment was the same in both treatment groups (mean 1.09 "years"/year in the first year); thus we anticipate a gain in final adult height of the order of 10 cm from employing the larger dose. The decrease in skin folds occurring on treatment, however, was no different with the larger than with the smaller dose. This reinforces previous observations that the short-term metabolic and longer-term auxologic effects of hGH are not necessarily related.

Adolescent↗
PubMed1975

The natural history of the Silver-Russell syndrome: a longitudinal study of thirty-nine cases.

The growth of 39 children with Silver-Russell syndrome has been followed for 1-13 years. Pregnancy and labor were normal; none of the 61 sibs had the syndrome. Height at referral (mean age 4.6 years) averaged 3.6 SD below the mean and remained at this level during subsequent growth. Bone age averaged 69 percent of normal at referral but caught up by puberty, which occurred at the normal time. Nineteen cases were treated with human growth hormone without lasting effect. There is no clear-cut distinction between the Silver and Russell syndromes; the name should be Silver-Russell. It is likely that some 10 percent of cases have birth weights in the minus 1.5 to minus 2.0 SD range.

Abnormalities, Multiple↗