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Biomedical subjects

M A Preece

Publications and source records attributed to M A Preece.

At least 217 records · Page 12Linked to original sources
PubMed1978

A new family of mathematical models describing the human growth curve.

A new family of mathematical functions to fit longitudinal growth data is described. All members derive from the differential equation dh/dt = s(t). (h1-h) where h1 is adult size and s(t) is a function of time. The form of s(t) is given by one of many functions, all solutions of differential equations, thus generating a family of different models. Three versions were compared. All were superior to previously described models. Model 1, in which s(t) was defined by ds/dt = (s1 - s)(s - s0) was especially accurate and robust, containing only five parameters to describe growth in stature from age two to maturity. Derived "biological" parameters such as Peak Height Velocity were very consistent between these three members of the family but, in some cases, differed signficantly from previous estimates.

Body Height↗
PubMed1978

Analysis of the human growth curve.

Mathematical techniques are well suited to analysis of growth data. In the past there has been much emphasis on the mathematical description of shape and changes of shape as exemplified by the allometric equation. More recently these methods have been less popular and shape analysis has been handled largely by modern multivariate statistical methods. In contrast, there has been an increasing interest in fitting models to size data, related to time. Many such functions have been described; some for small parts of the growth curve and others for the whole growing period. More recently single, non-linear functions have been developed and their properties and use are now described.

Adolescent↗
PubMed1977

Growth-hormone deficiency in congenital rubella.

Two boys with congenital rubella and concomitant growth-hormone deficiency responded to human-growth-hormone replacement and have already (over a period of 18 mo) achieved a significant increase in height. The association of these two diagnoses requires recognition so that treatable endocrine disorders, which are becoming recognized more often in congenital rubella, are always positively excluded when affected children with inexplicable short stature are seen.

Anthropometry↗
PubMed1977

Dextrostix-Eyetone in the insulin hypoglycaemia test.

The Ames Dextrostix-Eyetone system was evaluated for monitoring the blood glucose concentration during insulin-induced hypoglycaemia. The results agreed well with laboratory values for plasma glucose, obtained by an orthotoluidine method, and the method was practicable as a bedside technique. In two cases quick results obtained with the Eyetone enabled the insulin tolerance test to be interrupted to prevent severe hypoglycaemia before the clinical indications were obvious. The extra time and effort required were minimal, and its value seems to far outweigh the disadvantage of the extra work entailed. Nevertheless, care in using the system was important, and the operator must familiarise himself with the system before the most reliable results can be obtained.

Adolescent↗
PubMed1977

Results of intermittent treatment of growth hormone deficiency with human grwoth hormone.

The growth in stature of two groups of growth hormone deficient children has been compared. The frist group received intermittent treatment with human Growth Hormone (hGH), 1 year on, 1 year off, subsequent years on; the second group received continous treatment. This latter group had a significantly better mean growth response. The reduction in treatment velocity in years subsequent to the first was not prevented by the year off treatment, the mean velocity of the intermittent group in their 3rd year being the same as that of the continous group in their second. We conclude that intermittent hGH therapy is of less values than continous treatment and should be avoided, at least pending further evidence.

Age Determination by Skeleton↗
PubMed1976

Prevention of vitamin-D deficiency in Asians.

Asian families living in Glasgow were studied between December, 1973, and June, 1974. One group of families served as a control; their mean serum-25-hydroxy-vitamin-D (25-hydroxy-cholecalciferol and 25-hydroxyergocalciferol) remained low, being 5-1 +/- 0-8 (S.E.M.) ng/ml at the end of the study. A second group was given 3000 units of vitamin D2 in a capsule weekly; this raised the mean concentration of 25-hydroxy-vitamin-D to 18-1 +/- 2-9 ng/ml. The variable effectiveness of this supplement was attributable to some subjects not taking the capsules regularly. The third group of families was provided with chupatty flour fortified with vitamin D(6000 units per kg). This increased mean serum-25-hydroxy-vitamin-D very uniformly to a mean value of 19-5 +/- 1-2 ng/ml. It is concluded that vitamin-D deficiency in Asian immigrants could be substantially reduced by fortification of chupatty flour with vitamin D.

Adolescent↗
PubMed1976

Clinical and subclinical vitamin D deficiency in Bradford children.

A survey of the vitamin D status of Bradford schoolchildren was carried out in April 1973, employing conventional biochemistry, radiology, and measurement of 25-hydroxycholecalciferol levels. Biochemical evidence of rickets was present in 45% of the Asians. When re-examined in September, several children showed spontaneous biochemical resolution; nevertheless, radiological abnormalities were present in 12% of the original sample. No evidence of rickets was detected in the smaller White sample. Minor biochemical abnormalities were present in 9 of the 40 West Indian children. A study of admissions of Bradford hospitals in the 4 years 1969-1972 inclusive confirmed that clinical vitamin D deficiency was confined to Asians except for a few cases of infantile rickets in White children. The probability that one Asian child in 40 may require admission during the period from birth to adolescence emphasizes the urgent need for the introduction of prophylactic measures.

Adolescent↗
PubMed1976

The effect of administered corticosteroids on the growth of children.

The growth-inhibiting effect of exogenous corticosteroids has been reported in many papers. Most of them have concerned the clinical problems of asthma and rheumatoid arthritis but it is probable that the underlying disease is relatively unimportant in determining the effect on growth. Steroid therapy on alternate days seems to produce less undesirable effects than steroid treatment every day and corticotrophin may be preferable. Although the mechanisms are uncertain it seems likely that the action is peripheral and certainly exogenous growth hormone does not prevent the steroid effect. A minimal dosage of corticosteroids should always be used in replacement therapy for hypopituitarism.

Adolescent↗
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

Vitamin D status after resection of ileum in childhood.

Serum 25-hydroxycholecaliciferol levels and x-rays of the wrist were normal in children who had had extensive resections of ileum and no supplementary vitamin D for considerable periods. These results suggest that normal vitamin D status occurs in the absence of the ileum and that supplementary vitamin D is unnecessary.

Adolescent↗
PubMed1975

Studies of vitamin D deficiency in man.

Highly sensitive assays have been developed that enable 25-hydroxycholecalciferol (25-hydroxyvitamin D3) and 25-hydroxyergocalciferol (25-hydroxyvitamin D2) to be measured in the same serum sample. With these assays it has been shown that endogenously produced cholecalciferol (vitamin D3) is important in man; the findings further emphasize the role of vitamin D metabolites as hormones rather than vitamins in the traditional sense. Dietary sources of vitamin D appear to be inadequate and vitamin D deficiency has been shown to the cause of rickets and osteomalacia in Asian immigrants to Britain. This condition may be readily treated with small doses of vitamin D. In addition, sub-clinical deficiency was found in the Asian community. In the elderly, also, vitamin D deficiency was established as an important cause of osteomalacia and again evidence for the existence of a sub-clinical deficiency state was found. It is therefore suggested that the present prophylactic practices should be reviewed. Secondary hyperparathyroidism (reflected by elevated concentrations of circulating immunoassayable parathyroid hormone) was shown to be the rule rather than the exception in vitamin D deficiency. Some patients, however, had failed to respond to a hypocalcaemic stimulus. In others, there were high concentrations of parathyroid hormone despite normal serum calcium concentrations. Thus the relationship between parathyroid hormone and metabolites of vitamin D may not be mediated through changes in serum calcium alone, and it is postulated that metabolites of vitamin D may directly affect the secretion of parathyroid hormone.

Adolescent↗