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Biomedical subjects

A H Brook

Publications and source records attributed to A H Brook.

At least 73 records · Page 4Linked to original sources
PubMed1975

Oral hygiene instruction and motivation in children using manual and electric toothbrushes.

The effect of individual chairside instruction and motivation on children using either manual or electric toothbrushes was investigated. From 123 children aged 9-15 years attending the Children's Department, Eastman Dental Hospital, four groups were constructed. Group 1 acted as the control, Groups 2 and 3 used manual toothbrushes and received instruction and motivation, and Group 4 used electric toothbrushes (Touch Tronic, Teledyne Aqua Tec) and also received instruction and motivation. For all children, modified Löe and Silness' Gingival and Plaque Indices were scored, a disclosing agent applied and a prophylaxis completed. Children in Groups 2, 3 and 4 were additionally shown the disclosed plaque, and its importance was discussed. Their attempts to "get the stain off" were checked and their own brushing techniques modified. Re-examinations took place after 1 and 3 months. To estimate the reliability of the diagnosis, 172 of the 344 examinations were repeated by a second operator. The overall coefficient of correlation (between operators) was 0.8. In the control group no detectable improvement in the gingival health or oral cleanliness occurred over the 3-month study period. However, both gingival and plaque scores decreased significantly, by 35-50%, in all instructed and motivated groups within 1 month and this improvement was still observable 2 months later. There were no significant differences in improvement between motivated children using manual or electric toothbrushes.

Adolescent↗
PubMed1975

Variables and criteria in prevalence studies of dental anomalies of number, form and size.

Prevalence studies of dental anomalies of number, form and size have varied greatly in their findings. The purpose of this paper is to demonstrate from published studies the effect of variables in sampling techniques and examination methods and to suggest diagnostic criteria. In sampling the ethnic background, the sex distribution, age and derivation of the group studied are shown to be important, but the consumption of near optimum concentrations of fluoride in drinking water does not appear to influence findings. For the examination, a dental history is important and full radiographic coverage essential. Findings should be recorded separately for each dentition, while these anomalies should be studied as a group rather than singly. Diagnostic criteria are proposed for supernumerary teeth, hypodontia, invaginated teeth, double teeth, megadontia and microdontia.

Adolescent↗
PubMed1972

Renin responses to water restriction and rehydration.

1. The effect of restricted water intake and rapid rehydration was studied in three conscious sheep with respect to plasma renin concentration (PRC), blood corticosteroid levels, plasma protein and electrolyte concentrations, and the renal and faecal excretion of sodium and potassium.2. During water restriction the plasma concentrations of renin, protein and sodium rose while aldosterone levels were low or undetectable. Plasma potassium levels were unchanged. External sodium and potassium balance appeared to be unaffected.3. During rehydration the sheep drank more than their estimated water deficit in 3-4 min with the following effects: PRC rose three- to fourfold during the ensuing 12 hr. Aldosterone levels too rose, while plasma protein, sodium and potassium concentrations fell. Urinary sodium excretion virtually ceased for 24 hr, and urine flow rate increased only little during this period.4. If there was a single stimulus to renin release during water restriction and rehydration, it was not an alteration in vascular or extravascular volume, total body sodium, systemic B.P. or plasma sodium concentration.5. It is concluded that the rise in PRC in these experiments is compatible with the theory that altered sodium transport at the macula densa was the stimulus for renin release.

Aldosterone↗
PubMed1969

Circulatory changes and renin secretion in sheep in response to feeding.

1. The effect of feeding on the circulation, on renin release and on renal function has been examined in the sheep.2. There was a rapid reduction of plasma volume within 15 min of starting to eat dry feed.3. This was accompanied by an abrupt rise in systolic blood pressure and by a more gradual and prolonged elevation of heart rate.4. Within 30 min of feeding there occurred renal conservation of sodium and water which continued for at least 2-3 hr.5. Renin was released into the circulation of sheep that ate rapidly; slow feeders did not show this response.6. The rise in plasma renin concentration was inhibited by infusing a solution similar in composition to mixed saliva at a rate that prevented the change in plasma volume.7. It is concluded that the rapid transfer of sodium and water from the circulation to the rumen via the saliva during ingestion of dry feed is sufficient to activate the renin/angiotensin system.

Animals↗
PubMed1968

The function of antidiuretic hormone in the sheep.

1. With the aim of producing diabetes insipidus in sheep, electrolytic lesions were placed in the ventral medial hypothalamus immediately posterior to the optic chiasm.2. After formation of lesions, the pattern of urine excretion showed a triphasic response consisting of (i) an immediate diuresis reaching a maximum within 4 days, (ii) an interphase of about 12 days wherein rates of urine flow were normal, and (iii) a final phase of permanent polyuria. With the four sheep used in this work, the time between placement of the lesions and onset of permanent hyposthenuria was 19-22 days.3. In the final polyuric phase, the sheep were unable to concentrate their urine in response to dehydration or to feeding.4. Infusions of arginine vasopressin restored the ability of these animals to excrete urine that was hypertonic to plasma.5. The evidence showed that the hypothalamic lesions were effective in producing permanent diabetes insipidus. It was concluded that anti-diuretic hormone (ADH) has essentially the same function in sheep as it has in other mammalian species; that is, the hormone facilitates the elaboration of hypertonic urine. There was no evidence to suggest that ADH had a special effect on potassium excretion in the sheep.

Animals↗