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Biomedical subjects

C G Brook

Publications and source records attributed to C G Brook.

At least 235 records · Page 13Linked to original sources
PubMed1985

Constitutional delay of growth and puberty in boys: the effect of a short course of treatment with fluoxymesterone.

17 boys with delayed growth spurt, 9 of whom also had late puberty, were treated with 2.5 to 5.0 mg of fluoxymesterone daily for 0.23-0.58 years. Mean increment of growth velocity was 4.5 cm/year during treatment and this was maintained at 3.8 cm/year over a post-treatment observation period of 0.22-1.3 years. Mean testicular volume at the end of the treatment period was 9.9 ml. Mean height for bone age standard deviation score remained unchanged at -1.2 to -1.4 (not significant). We conclude that a low dose of fluoxymesterone may be used in safety for a short time to induce a growth acceleration in adolescent boys with constitutional delay of growth and puberty.

Adolescent↗
PubMed1985

Ovarian ultrasound assessment in normal children, idiopathic precocious puberty, and during low dose pulsatile gonadotrophin releasing hormone treatment of hypogonadotrophic hypogonadism.

Ultrasound assessment of ovarian volume, follicular size, and uterine growth was undertaken in 40 normal premenarcheal girls aged 6 months to 14 years. Ovarian follicles were detected from 6 months of age and increased in size and number, so that after the age of 8.5 years there was a progressive increase in the incidence of 'megalocystic' appearance. Eight girls with idiopathic precocious puberty had large megalocystic ovaries which regressed on treatment with gonadotrophin releasing hormone analogue. These findings contrasted with those seen in two prepubertal patients with hypogonadotrophic hypogonadism in whom the natural sequence of ovarian development was greatly accelerated by pulsatile administration of native gonadotrophin releasing hormone.

Adolescent↗
PubMed1985

Oxandrolone in low dose for constitutional delay of growth and puberty in boys.

Twenty four boys with delayed pubertal growth spurt were treated with oxandrolone (2.5 mg daily) for 0.21 to 0.65 years. The mean increment of growth velocity was 4.4 cm/year during treatment, which was maintained at 3.7 cm/year after treatment. There was no significant change in height for bone age standard deviation scores.

Adolescent↗
PubMed1985

Problems in the use of pulsatile gonadotrophin-releasing hormone for the induction of puberty.

The induction of puberty by the administration of subcutaneous 15-micrograms pulses of gonadotrophin-releasing hormone (GnRH) every 90 min during day and night is described in two patients. Too rapid an induction of puberty occurred in one patient while initial progress in the other ceased after the development of pituitary desensitisation. We have attributed these results to the use of GnRH pulses in too high amplitude, and we suggest a more appropriate dose regimen.

Adolescent↗
PubMed1985

Disturbances of puberty.

The initiation and progress of puberty requires progressive pulsatile stimulation of the pituitary by GnRH and of the gonads by LH and FSH. Gonadal maturation continues throughout childhood and is not confined to puberty. We have discussed the events of normal puberty and emphasized the consonance of the acquisition of different components of sexual maturation, including growth acceleration. Departure from this consonance is a sign of abnormality. The method by which constitutional delay of growth and puberty can be distinguished from gonadotrophin deficiency has been discussed as well as the treatment options for both conditions. We have emphasized the significance of pulsatile gonadotrophin secretion and how the development of a multicystic ovarian morphology on ultrasound can be used as a non-invasive assessment of gonadotrophin pulsatility in girls. Pulsatile GnRH therapy mimics normal puberty. The converse of suppressing the clinical signs of central precocious puberty can be achieved by abolishing gonadotrophin pulsatility with GnRH analogue therapy. We now recognize qualitative pulse abnormalities of gonadotrophin secretion which occur in isolated premature thelarche and in some cases of delayed puberty. Although clinical assessment remains the key to the diagnosis of disorders of puberty, studies of gonadotrophin pulsatility have aided our understanding and treatment of these conditions.

Adolescent↗
PubMed1984

Gonadotrophin responses to GnRH in precocious puberty treated with GnRH analogue.

The gonadotrophin releasing hormone analogue Buserelin was given by intranasal spray to 13 children with precocious puberty. The LH responses to GnRH reverted to prepubertal levels in the boys on 200-400 micrograms daily of the analogue while doses of 400-1200 micrograms daily were needed to suppress the girls. The significance of this apparent sex difference is uncertain.

Buserelin↗
PubMed1984

Plasma C peptide in hyperinsulinaemic hypoglycaemia.

We describe two children with hypoglycaemia due to pancreatic beta cell hyperactivity. Both had low serum insulin but raised plasma C peptide concentrations when hypoglycaemic. Measurement of C peptide is valuable in the diagnosis of hyperinsulinaemic hypoglycaemia in children.

C-Peptide↗
PubMed1984

Hypoplastic optic nerves and pituitary dysfunction. A spectrum of anatomical and endocrine abnormalities.

Fourteen children with optic nerve hypoplasia associated with either mid-brain abnormalities or pituitary dysfunction, or both, are described. All patients were either partially sighted or blind. One case is reported in detail. The importance of hypoglycaemia in the neonatal period and later in childhood is emphasised in relation to diagnosis and developmental delay. Pituitary dysfunction is variable and may be progressive. Forty percent of the patients had a septum pellucidum and its presence or absence cannot be used as a radiological marker for the condition. Long term endocrine follow up of these patients is required.

Adolescent↗
PubMed1984

Hyponatraemia in the first week of life in preterm infants. Part I. Arginine vasopressin secretion.

Continuous sequential urinary arginine vasopressin measurements in 14 preterm, ventilated infants suggest that both osmoreceptor and volume receptor systems are able to stimulate the prolonged secretion of arginine vasopressin from 26 weeks' gestation. The kidney is able to respond to arginine vasopressin stimulation from the first day of life and from 26 weeks' gestation. A maximum urine osmolality not exceeding 550 mOsm/kg was reached which varied with hydration of the infant. Excretion of arginine vasopressin and urine osmolality increased during deterioration of respiratory illness, mask ventilation, bilateral pneumothoraces, and severe intraventricular haemorrhage. The data show that inappropriate arginine vasopressin secretion is common during illness in the first week of life in preterm infants and that strict attention must be paid to water balance during this time.

Arginine Vasopressin↗
PubMed1984

Hyponatraemia in the first week of life in preterm infants. Part II. Sodium and water balance.

Serial measurements of plasma sodium, sodium balance, water intake, and urine volume were made for a mean period of 5.9 days in 10 preterm infants of mean gestation 30.5 weeks and mean birthweight 1506 g. In five infants weighed regularly, estimates of insensible water loss averaged 2.6 (range 1.4 to 6.2) ml/kg/hour. High insensible water losses were the cause of hypernatraemia that occurred in two of the 10 infants. Net sodium balance was negative during the study and represented contraction of the extracellular fluid volume associated with weight loss. The negative sodium balance did not seem diminished by increasing sodium intake and there was no evidence that sodium intake need exceed 3 to 4 mmol/kg/day. Hyponatraemia was not due to changes in sodium balance but to water retention associated with inappropriate increases in urinary arginine vasopressin excretion and urine osmolality in 8 of 10 infants. Frequent, accurate measurements of body weight and of plasma sodium are the two most reliable indicators of changes in water balance.

Age Factors↗
PubMed1983

A mixed longitudinal study of adrenal steroid excretion in childhood and the mechanism of adrenarche.

Twenty four-hour urine samples have been collected 6 monthly for 18 months from 127 normal boys aged between 7.5 and 17 years. Urinary steroid metabolites have been measured by gas-liquid chromatography and ratios of steroid metabolites used to draw conclusions about likely enzymic activities at each step in the adrenal biosynthetic pathway. DHA excretion rose throughout the study, especially between 7.5 and 11 years. Metabolites of cortisol and corticosterone did not increase when related to surface area. During adrenarche there were changes consistent with a decrease in 3 beta-hydroxysteroid dehydrogenase activity, a slight rise in 17 alpha hydroxylase activity, a marked rise in 17,20 lyase activity, and a fall in 11 beta hydroxylase activity. These data are compatible with the hypothesis that a small reduction in the ability to synthesize cortisol requires a marginal increase in the secretion of ACTH and/or other CRF-induced peptides to maintain cortisol production rate. ACTH itself or a dexamethasone-suppressible CRF-induced peptide would in such a case control the growth of the zona reticularis at adrenarche, which thus appears to be primarily an adrenal event.

3-Hydroxysteroid Dehydrogenases↗
PubMed1983

Spontaneous hypothermia in a young boy.

A 13-year-old boy who maintains his body temperature between 33 and 35 degrees C was investigated. Tests of peripheral and central thermoregulatory function did not show a specific abnormality, except for some generalised hypothalamic dysfunction of unknown aetiology. He responded appropriated when his temperature was altered from its usual low level. His temperature regulatory mechanisms appeared to be set at a temperature lower than is normal.

Adolescent↗
PubMed1983

Continuous urine collection in the study of vasopressin in the newborn.

We have evaluated the use of urinary vasopressin (AVP) measurements in human newborns to see if urinary AVP excretion is a true reflection of the plasma level. AVP was measured in 37 simultaneously collected plasma and urine samples. The correlation coefficient was 0.8 (p less than 0.001). AVP extracted in duplicate from six urine samples was measured by bioassay and radioimmunoassay. The correlation coefficient was 0.85 (p less than 0.05). To facilitate long-term urine collection we have developed a urine collecting tray to fit a standard incubator or cot. Urinary AVP as measured in 24-hour urine collections in 37 normal infants. AVP excretion was higher in the first 48 h of life than subsequently. Continuous 4-hour urine collections were made in 1 sick infant to assess AVP excretion when urine flow is variable.

Animals↗