Comparing different measures of energy expenditure in human subjects resident in a metabolic facility.

OBJECTIVE: To compare energy expenditure (EE) measured by doubly labeled water (DLW) with other measures, both physical and based on subjective questionnaires. DESIGN: A comparison of methods in a stratified sample of adult volunteers. SETTING: The feeding behaviour suite (FBS) at the Rowett Research Institute, Aberdeen. SUBJECTS: A total of 59 subjects, stratified for age, sex and body mass index (BMI). INTERVENTIONS: EE was assessed by DLW (validated using measurements of energy balance), heart rate monitor (HRM), activity monitor (Caltrac), 24-h physical activity diary (PAD) and 7-day physical activity recall. Energy intake was assessed using covert (investigator-weighed) food intake (EI). Data were collected over a 12-day period of residence in the Rowett's FBS. RESULTS: No methods correlated highly with physical activity assessed by DLW. Physical methods correlated more closely than did subjective recording. All methods (except EI) significantly underestimated EE, estimated by DLW. There were no significant differences in association between methods and sex, age, BMI or fat-free mass. CONCLUSION: EE is difficult to measure precisely or accurately with current approaches but physical methods are slightly better than subjective accounts.

Plausible self-reported dietary intakes in a residential facility are not necessarily reliable.

BACKGROUND/OBJECTIVES: Comparing reported energy intakes with estimated energy requirements as multiples of basal metabolic rate (Ein:BMR) is an established method of identifying implausible food intake records. The present study aimed to examine the validity of self-reported food intakes believed to be plausible. SUBJECTS/METHODS: One hundred and eighty men and women were provided with all food and beverages for two consecutive days in a residential laboratory setting. Subjects self-reported their food and beverage intakes using the weighed food diary method (WDR). Investigators covertly measured subjects' actual consumption over the same period. Subjects also reported intakes over four consecutive days at home. BMR was measured by indirect calorimetry. RESULTS: Average reported energy intakes were significantly lower than actual intakes (11.2 and 11.8 MJ/d, respectively, P<0.001). Two-thirds (121) of the WDR were under-reported to varying degrees. Only five of these were considered as implausible using an Ein:BMR cut-off value of 1.03*BMR. Under-reporting of food and beverage intakes, as measured by the difference between reported and actual intake, was evident at all levels of Ein;BMR. Reported energy intakes were lower still (10.2 MJ/d) while subjects were at home. CONCLUSIONS: Under-recording of self-reported food intake records was extensive but very few under-reported food intake records were identified as implausible using energy intake to BMR ratios. Under-recording was evident at all levels of energy intake.

Increasing the impact of European obesity research in preparation for the European research area: a report on the 2003 European Commission Obesity Workshop.

Leading obesity researchers from across Europe assembled in Aberdeen, Scotland, in January 2003 to consider how to increase the impact of European obesity research. The workshop was funded by the European Commission and hosted by the Rowett Research Institute, Aberdeen. The delegates identified the need to (i) develop a portfolio of studies that integrate genetics and mechanisms through parallel study of humans and animal models and (ii) establish major intervention studies in weight management and early life nutrition. It was recommended that these goals would be best achieved under the umbrella of a virtual European Obesity Research Institute, or Network of Excellence in Obesity Research under Framework Programme 6, that would facilitate harmonization of methodology, manage centralized standardized resources, coordinate training initiatives, workshops and working groups, and increase focus.

Description and evaluation of an experimental model to examine changes in selection between high-protein, high-carbohydrate and high-fat foods in humans.

OBJECTIVE: To develop and test an experimental model designed to detect changes in selection between foods individually enriched in protein, carbohydrate and fat in human subjects. DESIGN: Randomised counterbalanced (Latin square) design. SETTING: The metabolic suite at the Rowett Research Institute's Human Nutrition Unit. SUBJECTS: 16 normal-weight men (mean BMI = 23.5). INTERVENTIONS: Subjects were each studied 4 times in a 2-day protocol. On day 1 subjects received a fixed maintenance diet; on day 2 they received a mandatory intake as breakfast (08.30) plus a drink at 10.30. This comprised 80% of resting energy requirements as high-protein (HP), high-carbohydrate (HC) or high-fat (HF) foods (60% of energy in each case) or an equal mixture (M) of macronutrients, 33% by energy. All mandatory treatments contained the same energy content and density. From 12.30 onwards, subjects had ad libitum access to a counter-balanced selection of three groups of familiar foods (10 HP, 10 HC and 10 HF; 30 foods in total). Most energy in each food was derived from one macronutrient (approximately 60%), the remainder being equally split between the other two macronutrients. RESULTS: Subjects were significantly less hungry before lunch on the HP and M (33% protein) treatments (F3.44 = 7.35; P < 0.001). At lunch, they ate more energy after the HF treatment than after any of the other treatment (F1,38 = 9.00; P = 0.005). This was largely in the form of fat and protein, and to a lesser extent carbohydrate. Subsequent energy intake (EI) were lower on the HF treatment, largely through selection of less fat in the afternoon (F1.42 = 6.90; P=0.012). Daily EIs were similar across treatments. CONCLUSION: This design appears sensitive meal-to-meal to changes in both nutrient and EIs.

Field trials to determine a suitable injection dose of bovine PPD tuberculin for the diagnosis of bovine tuberculosis in naturally infected cattle.

Biological assays carried out in the Republic of Ireland in naturally sensitized (M. bovis infected) tuberculous cattle have shown that Rotterdam and Weybridge bovine PPD tuberculins issued for routine use in 1981 and 1982 were equipotent with an estimated potency of about 24,000 Community Tuberculin Units (C.T.U.) per mg of PPD. However, previously it was shown that Weybridge bovine PPD produced in 1978 had only a potency of about 4,000 C.T.U./mg in M. bovis infected cattle. The clinical significance of the latter finding is seen in the results of field trials carried out in the Republic of Ireland in 1978 to determine the relative diagnostic abilities of Weybridge and Rotterdam, routine issue bovine PPD tuberculins. These trials involved the tuberculin testing and slaughter of naturally sensitized cattle. Post-mortem and laboratory examination confirmed that 68 of these animals were infected with M. bovis. It was concluded that the injection dose for the diagnosis of bovine tuberculosis in cattle should not contain less than 2,000 C.T.U. and that the use of an injection of double this dosage was desirable in known M. bovis infected herds.

The epidemiology of Mycobacterium bovis infections in animals and man: a review.

Tuberculosis is primarily a respiratory disease and transmission of infection within and between species is mainly by the airborne route. Mycobacterium bovis, the cause of bovine-type tuberculosis, has an exceptionally wide host range. Susceptible species include cattle, humans, non-human primates, goats, cats dogs, pigs, buffalo, badgers, possums, deer and bison. Many susceptible species, including man, are spillover hosts in which infection is not self-maintaining. In countries where there is transmission of infection from endemically infected wildlife populations to cattle or other farmed animals, eradication is not feasible and control measures must be applied indefinitely. Possible methods of limiting spread of infection from wildlife to cattle including the use of vaccines are outlined. The usefulness of DNA fingerprinting of M. bovis strains as an epidemiological tool and of BCG vaccination of humans and cattle as a control measure are reviewed. The factors determining susceptibility to infection and clinical disease, and the infectiousness of infected hosts and transmission of infection, are detailed. Reports of the epidemiology of M. bovis infections in man and a variety of animal species are reviewed. M. bovis infection was recognised as a major public health problem when this organism was transmitted to man via milk from infected cows. The introduction of pasteurization helped eliminate this problem. Those occupational groups working with M. bovis infected cattle or deer, on the farm or in the slaughter house, are more likely to develop pulmonary disease than alimentary disease. In recent years, tuberculosis in farmed cervidae has become a disease of economic as well as public health importance in several countries. Nowadays, the human immunodeficiency virus (HIV) is associated with a greatly increased risk of overt disease in humans infected with Myobacterium tuberculosis. It is believed this increased risk also occurs in the case of M. bovis infections in humans.

The potency of bovine PPD tuberculins in guinea-pigs and in tuberculous cattle.

Potency differences between bovine purified protein derivative tuberculin preparations produced in two different centres and also between preparations produced within these centres, were detected in tuberculous cattle and correlated with potency differences in guinea-pigs. Although assays in groups of guinea-pigs sensitized with either killed Mycobacterium bovis or live BCG identified the weak batches and listed the tuberculins in the same order of potency as the cattle assays, there were nevertheless significant differences between potency estimates according to the mode of sensitization and the preparations compared. The implications for the standardization of tuberculin preparation in general are discussed.

The effect of covertly manipulating the energy density of mixed diets on ad libitum food intake in 'pseudo free-living' humans.

OBJECTIVE: This study examined the effects of covert alterations in the energy density (ED) of mixed, medium fat (MF) diets on ad libitum food and energy intake (EI), subjective hunger and body weight in humans. DESIGN: Randomised cross-over design. Subjects were each studied three times (factorial design), during 14d, throughout which they had ad libitum access to one of three covertly-manipulated MF diets. SUBJECTS: Six healthy men, mean age (s.e.m.) = 30.0 y (12.76 y), mean weight = 71.67 kg (19.80 kg); mean height = 1.79 m (0.22 m), body mass index (BMI) = 22.36 (2.60) kg/m2, were studied. The fat, carbohydrate (CHO) and protein in each diet (as a proportion of the total energy) and energy density (ED) were, low-ED (LED), 38:49:13%; 373 kJ/100 g; medium-ED (MED), 40:47:13%; 549 kJ/100 g; high-ED (HED), 39:48:13%; 737 kJ/100 g. Subjects could alter the amount but not the composition of foods eaten. They were resident in (but not confined to) a metabolic suite throughout the study. RESULTS: Solid food intake decreased as ED increased, giving mean values of 2.84, 2.51 and 2.31 kg/d, respectively. This was insufficient to defend energy balance, since energy intake increased with increasing ED (F(2,10) 16.08; P < 0.001) giving mean intakes of 10.12, 12.80 and 16.17 MJ/d, respectively. Rated pleasantness of food (measured on visual analogue scales) was not significantly different between diets nor was subjective hunger different between the LED, MED and HED diets, respectively. Diet significantly affected body weight (F(2,10) = 4.62; P = 0.038), producing changes of -1.20, 0.02 and 0.95 kg, respectively, by day 14. CONCLUSION: Dietary ED can influence EI and body weight, since changes in amount eaten alone are insufficient to defend energy balance, when subjects feed on unfamiliar diets and diet selection is precluded. Comparison with our previous studies suggest that there was compensation in solid food intake when ED was altered using mixed diets (as in this study) compared to previous studies which primarily used fat or CHO to alter dietary ED.