Alan Dugdale

A model for the prediction of energy balance and body weight

A model for changes in energy balance and body weight is described which can be written as an iterative computer program. Medium and long-term changes in body weight resulting from random daily fluctuations in energy balance are quantitatively predicted. Body weight varies periodically about a mean value to to the extent of +/- 1 kg over a span of a few weeks. Long-term weight stabilization is the result of a dynamic equilibrium between energy intake and output which depends on activity and tissue metabolism. A lean : fat tissue deposition ratio defines the metabolic type of individual. This ration, which is constant for each individual, governs the proportions in which these tissues are both deposited and mobilized. In the model, the ratio has an important effect on the magnitude and composition of the weight gains resulting from over-eating. It is suggested that the differences in response which have been observed in over-eating experiments result from inter-individual differences in this ratio.

MECHANISMS FOR THE CONTROL OF BODY-WEIGHT

Various hypotheses for the mechanism of regulation of body-weight in human adults have been proposed in the light of the magnitude of the long-term changes in weight actually observed. One of these hypotheses has been represented in the form of a computer simulation model which has been used to demonstrate that (i) it is not necessary to postulate the existence of a set-point regulatory system, and (ii) in practice, several mechanisms, including hunger and satiety, the relative constancy of habits and customs of behaviour, and the existence of cognitive thresholds combined with a relatively simple physiological negative feedback system probably constitute the simplest hypothesis for the mechanism of weight stability.

A model of seasonal changes in energy balance

In developing countries, many peasant farmers experience regular seasonal changes of body weight, so that the adequacy of food energy supply cannnot be assessed simply in terms of energy balance and a desirable body weight. A computer simulation model has been devised, which predicts the pattern of changes in body weight which result from the annual cycle of agricultural work load, and the way in which food consumption is regulated over the year. The model also includes the effect of post‐harvest storage losses. The actual observed patterns of food use of farmers in The Gambia, and in Burma, are first of all used to simulate the seasonal changes in body weight and these agree well with observations. The effects of alternative strategies of food use are then tried, ranging from a constant intake throughout the year, to an exaggerated feasting and fasting cycle. The simulations show that the actual food allocation patterns adopted by these two peasant populations constitute an optimum strategy in which the ...

Predicting iron and folate deficiency anaemias from standard blood testing: the mechanism and implications for clinical medicine and public health in developing countries.

BackgroundDeveloping countries have high prevalence of diseases, but facilities to diagnose and treat them are limited. We must use available resources in ways not needed where there are sophisticated equipment and trained staff. Anaemia is common; iron deficiency affects health and productivity; folate deficiency in pregnant women causes foetal abnormalities. Few developing countries can measure serum folate or ferritin, but standard automated blood analyses are widely available and can help predict folate and iron deficiency. The RDW-CV% (coefficient of variation of the red cell width) measures the variability in the size of red blood cells (RBC) in routine automated analysis of blood cells, but is seldom reported. Levels of RDW-CV% and haemoglobin (Hb) can predict iron deficiency anaemia.Method and resultsI have written a computer model based on the standard mechanism for blood formation and destruction. This shows that before anaemia develops and during recovery, there are both normal and abnormal RBC (small in iron deficiency and large in folate deficiency) in the circulation. The model calculates the abnormality in the RDW-CV% in standard automated blood analyses. In early iron deficiency and during recovery the full blood count shows the Hb near the lower limit of normal, a low MCV and a high RDW-CV%. A similar pattern, but with a higher MCV, develops in folate deficiency. Folate deficiency is often brief and may not cause anaemia. The high RDW-CV% may persist for three months.ConclusionThis long footprint could be medically useful for detecting folate deficiency and so limiting foetal damage in individuals and communities. Few clinicians or public health workers know about RDW-CV%. Standard blood reports for clinical use should include the RDW-CV% and note the possible significance of abnormal values.

Evidence Behind the WHO Guidelines: Hospital Care for Children: What is the Most Effective Antibiotic Regime for Chronic Suppurative Otitis Media in Children?

The World Health Organization (WHO) has produced guidelines for the management of common illnesses in hospitals with limited resources. This series reviews the scientific evidence behind WHO’s recommendations. The WHO guidelines, and more reviews are available at http://www.ichrc.org This review addresses the question: What is the Most Effective Antibiotic Regime for Chronic Suppurative Otitis Media in Children? The WHO Pocketbook of Hospital Care for Children suggests to keep the ear dry by wicking. Instill topical antibiotic or antiseptic ear drops (with or without steroids) once daily for 2 weeks. Drops containing quinolones (norfloxacin, ofloxacin, ciprofloxacin) are more effective than other antibiotic drops (p. 163).

EVOLUTION AND INFANT FEEDING

The darwinian theory of evolution has been used to justify the statement that breast-milk is ideal for infants. However, a broader interpretation of the theory suggests that the mother-child dyad is the evolutionary unit. For the survival of the species, both mother and child should benefit. Simple arithmetic shows that where there is a conflict of interests, the welfare of the mother outweighs that of the infant. The dyad hypothesis suggests that the maximum evolutionary gain is obtained when protein and energy levels in breast-milk are just high enough to prevent prohibitive infant mortality rates, but low enough to spare the mother. The anti-infective constituents of breast-milk are very small in bulk, so they place a minimum metabolic load on the mother but have a large benefit for the child. The contraceptive effect of breast feeding is pronounced only when the mother is malnourished. A separation of the nutritive from the anti-infective properties of breast-milk suggests that a rational method of infantfeeding for many mothers is to breast-feed for several months to reduce the morbidity rate in the infant, but to give supplementary milks, formulae, and foods when needed to promote the babys nutritional status.

Sequelae of Haemophilus influenzae meningitis

Fourteen children who had had Haemophilus influenzae meningitis more than two years earlier have been compared with their siblings. WISC, Frostig and Bender psychological tests and neurological examination were performed so that subject/sibling differences could be analysed. On neurological examination, subjects overall performed worse than the controls, although no “hard” neurological signs were found. Prolonged fever during the meningitis was associated with poorer results in psychological tests. In the subjects, there was a significant increase in left lateral dominance which may have been due to brain damage by the meningitis. However, most subjects did not differ significantly from their siblings in the tests, suggesting that prompt and adequate treatment of bacterial meningitis can prevent sequelae.

Body build and the desire for slenderness in young people

The median weight‐for‐height of young people in Brisbane are below the ‘standard’ values. In most groups the weight‐for‐height are symmetrically distributed, suggesting that this is the range of normal variation. Only among girls aged 15‐19 years was there an excess of ‘obese’ subjects.

Patterns of weight growth in Aboriginal children on Queensland communities

Abstract We have used data from existing health records to study the birthweights and percentage weights for age (%W/A) of children in five Aboriginal communities in Queensland. The data are from cohorts of children born in the 1950s‐80s at Cherbourg, the 1960s‐80s at Yarrabah and the 1970s‐80s in Woorabinda, Palm Island and Doomadgee. Birthweights have not changed significantly in any of the communities and generally remain below the international level. The weights for 1 and 5 year old children have improved significantly at Cherbourg and Palm Island, but have dropped significantly at Doomadgee. The overall pattern is for children on remote communities to have a lower %W/A and less improvement in %W/A than those closer to population centres. Other workers have found the same pattern elsewhere. These patterns of growth are probably not directly related to the level of general health services, but rather to other facilities available and attitudes of mothers to child care. The results also show that Aboriginal children can reach international levels of %W/A, so the poor growth in many communities is potentially preventable.

Deafness after bacterial meningitis.

Seventeen children with previous bacterial meningitis and 17 sib controls were examined clinically and otoscopically. They were also tested with air-conduction and bone-conduction audiometry and evaluated by tympanometry. There were no major neurological abnormalities and few otoscopical signs of ear disease. 21% of the ears showed abnormalities on air-conduction audiometry but all were normal on bone-conduction audiometry. 30% had abnormal middle-ear pressures (more negative than 100 mm water) on tympanometry and 7% had abnormal compliance of the drum. There were no significant differences on any test between the postmeningitis children and the sib controls. Population studies have confirmed that minor hearing loss due to middle-ear dysfunction is common in children, but is probably temporary in most of them. We have found no excess of middle-ear dysfunction and no sensorineural deafness in these postmeningitis children, but other workers have shown that nerve deafness may occur in association with clinical neurological damage. However, much of the deafness attributed to bacterial meningitis in other studies may well reflect population variability.