PubMed Health⌕ Search

Biomedical subjects

S A Jebb

Publications and source records attributed to S A Jebb.

69 records · Page 4Linked to original sources
PubMed1994

Incidence and recognition of malnutrition in hospital J. P. McWhirter and C. R. Pennington BMJ 1994; 308: 945-948.

This paper describes a prospective study to determine the incidence of malnutrition among patients on admission to an acute teaching hospital, to monitor their changes in nutritional status during stay and to determine awareness of nutrition in different clinical units. Nutritional status was assessed in 500 patients admitted to hospital: 100 each from general surgery, general medicine, respiratory medicine, orthopaedic surgery and medicine for the elderly. The main outcome measures were weight, height, triceps skinfold thickness, mid arm circumference, mid arm muscle circumference and grip strength. Patients were studied on admission and discharge and case notes reviewed for information about nutritional status. On admission 200 out of 500 patients were considered undernourished (BMI < 20). Of these only 96 had any nutritional information documented in the notes. 34% of patients were overweight (BMI > 25). The 112 patients reassessed on discharge had a mean weight loss of 5.4% with the greatest weight loss in those initially most malnourished. The 10 patients who were referred for nutritional support (3 for parenteral nutrition, 7 for enteral nutrition) showed a mean weight gain of 7.9%.

Journal Article↗
PubMed1994

5-fluorouracil and folinic acid-induced mucositis: no effect of oral glutamine supplementation.

In some clinical situations the endogenous production of glutamine may be insufficient to maintain optimal tissue structure and function such that glutamine becomes a conditionally essential amino acid. Studies in laboratory animals have demonstrated that glutamine supplementation can reduce the incidence and severity of cytotoxic-induced mucositis. This study examined the role of oral glutamine supplementation in the management of mucositis caused by 5-fluorouracil (5-FU) and folinic acid. Twenty-eight patients with gastrointestinal cancers were randomised to receive 16 g of glutamine per day for 8 days, or placebo, in a randomised double-blind trial before crossing over to the alternative supplement during the second treatment cycle. The supplement was well tolerated with no apparent adverse effects, but failed to have any significant effect on oral mucositis assessed by the patients or investigator. The possible reasons for this apparent lack of benefit are discussed.

Administration, Oral↗
PubMed1994

Measurements of resting energy expenditure and body composition before and after treatment of small cell lung cancer.

BACKGROUND: Many patients with small cell lung cancer are reported to lose weight, but the mechanism of this effect is unclear. PATIENTS AND METHODS: Measurements of resting energy expenditure (REE), using indirect calorimetry and body composition (fat, fat-free mass and organ mass), using dual energy X-ray absorptiometry (DXA) and abdominal CT scans were measured in 38 patients with newly-diagnosed small cell lung cancer. Twenty-eight patients were restudied at the end of treatment. RESULTS: In those who responded to treatment there was no change in body weight, but a decrease in REE of 15.7 +/- 11.7 kJ/kg fat free mass/day, whilst in the non-responders body weight decreased 4.33 +/- 5.4 kg, but REE was unchanged. CONCLUSIONS: This study provides evidence for tumour-induced hypermetabolism which is independent of changes in gross body composition, although the absolute increase is small, approximately 0.8 MJ/day. However since body weight was maintained in those patients who responded to treatment either total energy expenditure was decreased, implying decreases in physical activity, or energy intake was increased.

Absorptiometry, Photon↗
PubMed1993

DXA measurements of fat and bone mineral density in relation to depth and adiposity.

Significant effects of depth and adiposity on measurements of fat have been observed, which if also true in-vivo, have important implications for studies at the extremes of body composition, or for longitudinal measurements in subjects who show large changes in tissue thickness. Measurements of BMD under similar circumstances appear to be more robust. However, assessments of the absolute accuracy of DXA measurements await comparison with chemical analysis of human or animal cadavers.

Absorptiometry, Photon↗
PubMed1993

Measurements of total energy expenditure provide insights into the validity of dietary measurements of energy intake.

The quantification of errors inherent in methods of measuring dietary intake has been handicapped by the absence of independent markers for testing their validity. The doubly labeled water technique permits a precise measure of energy expenditure in free-living persons. Because energy expenditure must equal energy intake in populations in energy balance, this technique may be used to validate the assessment of energy intake. A series of studies demonstrated good agreement between mean energy intake and mean energy expenditure when food intake was recorded by observers or when it was self-reported by normal-weight, self-selected, highly motivated volunteer subjects using weighed records. However, in randomly recruited men and women, energy intake by weighed records was 82% and 81%, of energy expenditure, respectively, indicating underestimation of habitual intake. Men and women in the lowest third of reported intake recorded energy expenditure of only 69% and 61%, respectively. Reported intake of obese and previously obese women was only 73% and 64% of expenditure, whether measured by weighed record or by diet history, confirming suspicions that these subjects misrepresented their intake. Acceptable weighed records were obtained from 7- and 9-year-olds whereas 15- and 18-year-olds underestimated intake. Diet histories taken from the same children tended to overestimate intake. These studies suggest that, ideally, all dietary studies should include independent measures of validity.

Adolescent↗
PubMed1993

In vivo measurement of changes in body composition: description of methods and their validation against 12-d continuous whole-body calorimetry.

The accuracy of a variety of in vivo body-composition techniques (densitometry, total body water, skinfold thicknesses, whole-body impedance and resistance, body mass index, and two three-compartment models) was assessed by comparison with fat balance. Three subjects were overfed and three underfed while confined to a 30-m3 whole-body calorimeter continuously for 12 d. Mean weight changes were +2.90 kg during overfeeding and -3.47 kg during underfeeding. The change in fat mass accounted for 37.1% during overfeeding and 59.3% during underfeeding. In comparison with energy and nitrogen balance, a three-compartment model yielded the least bias and greatest precision. The smallest change in fat mass that can be measured by such a method in an individual subject is 1.54 kg (2 SD). Of the prediction techniques considered, skinfold thicknesses or the body-mass-index formula appear to be more precise than estimates based on resistance or impedance.

Adolescent↗
PubMed1993

Techniques for the measurement of body composition: a practical guide.

This paper discusses some of the practical aspects of both reference body composition methods (densitometry, isotope dilution methods, in vivo neutron activation analysis, dual energy X-ray absorptiometry, computerized tomographic scanning and magnetic resonance imaging) and bedsides or field techniques (weight and height indices, skinfold thicknesses impedance/resistance, near infra-red interactance and 24 hour creatinine excretion). Some techniques measure gross composition, in terms of fat and fat-free mass, or the components of fat-free tissue, such as water, mineral and protein, while other methods measure the mass of individual tissues, organs or body segments. The choice of a specific method for a particular study depends on various considerations including accuracy, precision, subject acceptability, convenience, cost, radiation exposure, and the need for observer training. The relative advantages and disadvantages of each method are discussed with these considerations in mind.

Absorptiometry, Photon↗
PubMed1992

Four-component model for the assessment of body composition in humans: comparison with alternative methods, and evaluation of the density and hydration of fat-free mass.

1. Body composition was assessed in 28 healthy subjects (body mass index 20-28 kg/m2) by dual-energy X-ray absorptiometry, deuterium dilution, densitometry, 40K counting and four prediction methods (skinfold thickness, bioelectrical impedance, near-i.r. interactance and body mass index). Three- and four-component models of body composition were constructed from combinations of the reference methods. The results of all methods were compared. Precision was evaluated by analysis of propagation of errors. The density and hydration fraction of the fat-free mass were determined. 2. From the precision of the basic measurements, the propagation of errors for the estimation of fat (+/- SD) by the four-component model was found to be +/- 0.54 kg, by the three-component model, +/- 0.49 kg, by deuterium dilution, +/- 0.62 kg, and by densitometry, +/- 0.78 kg. Precision for the measurement of the density and hydration fraction of fat-free mass was +/- 0.0020 kg/l and +/- 0.0066, respectively. 3. The agreement between reference methods was generally better than between reference and alternative methods. Dual-energy X-ray absorptiometry predicted three- and four-component model body composition slightly less well than densitometry or deuterium dilution (both of which greatly influence these multi-component models). 4. The hydration fraction of fat-free mass was calculated to be 0.7382 +/- 0.0213 (range 0.6941-0.7837) and the density of fat-free mass was 1.1015 +/- 0.0073 kg/l (range 1.0795-1.1110 kg/l), with no significant difference between men and women for either. 5. The results suggest that the three- and four-component models are not compromised by errors arising from individual techniques.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1992

Effects of weight cycling on body composition.

It is frequently claimed that weight cycling, or "yo-yo" dieting, causes an inappropriate and permanent loss of lean body mass (LBM). Data are presented from a rural African population that undergoes profound weight cycling caused by an annual hungry season. No detrimental effect on LBM was observed. Data are also presented from an 18-wk prospective study of moderately obese British women who underwent three cycles of VLCD-induced weight loss and subsequent relapse. The proportion of weight lost as LBM was no greater than predicted. A review of the published results from experimental weight cycling in small animals also shows a high level of consensus that cycling does not significantly alter body composition. We conclude that, although weight cycling may affect growth of young animals, metabolic efficiency, and health, these effects are not mediated through permanent alterations in body composition.

Adipose Tissue↗
PubMed1991

Assessment of changes in total body water in patients undergoing renal dialysis using bioelectrical impedance analysis.

This study aimed to assess whether changes in fluid can be accurately predicted from the change in whole-body impedance with an appropriate correction for the conductor length (i.e. height). Eight studies to measure changes in impedance were performed on six patients during dialysis. The measured loss of fluid from the beginning to the end of dialysis (1174+/-706ml) agreed well with the change in body weight (1188+/-768kg). The regression lines of the plot of change in height(2)/impedance versus loss of fluid for each subject had correlation coefficients ranging from 0.880-0.999, but there was a four-fold variation in the slopes of the different curves. The mean +/- SD change in height(2)/impedance during the removal of 0.5, 1 and 2l of water was 1.75+/-0.96, 3.41+/-1.55 and 6.72+/-2.91 m(2)/ohms respectively. The total change in body water, calculated by a variety of prediction equations, overestimated the loss of fluid by a mean of between 86 and 100%. The lack of a fixed relationship between changes in impedance and changes in body water precludes the use of the impedance technique as a means of accurately assessing small fluid changes in this patient group.

Journal Article↗
PubMed1991

Critical evaluation of energy intake data using fundamental principles of energy physiology: 1. Derivation of cut-off limits to identify under-recording.

This paper uses fundamental principles of energy physiology to define minimum cut-off limits for energy intake below which a person of a given sex, age and body weight could not live a normal life-style. These have been derived from whole-body calorimeter and doubly-labelled water measurements in a wide range of healthy adults after due statistical allowance for intra- and interindividual variance. The tabulated cut-off limits, which depend on sample size and duration of measurements, identify minimum plausible levels of energy expenditure expressed as a multiple of basal metabolic rate (BMR). CUT-OFF 1 tests whether reported energy intake measurements can be representative of long-term habitual intake. It is set at 1.35 x BMR for cases where BMR has been measured rather than predicted. CUT-OFF 2 tests whether reported energy intakes are a plausible measure of the food consumed during the actual measurement period, and is always more liberal than CUT-OFF 1 since it has to allow for the known measurement imprecision arising from the high level of day-to-day variability in food intake. The cut-off limits can be used to evaluate energy intake data. Results falling below these limits must be recognized as being incompatible with long-term maintenance of energy balance and therefore with long-term survival.

Adult↗
PubMed1991

Critical evaluation of energy intake data using fundamental principles of energy physiology: 2. Evaluating the results of published surveys.

The fundamental principles of energy physiology were used to evaluate the validity of reported energy intake (EI) in 37 published dietary studies of adults providing 68 subgroups when classified according to sex and dietary method. EI was expressed as a multiple of BMR estimated using the reported heights and weights of the study populations (EI:BMR(est)). This ratio was compared with a study-specific cut-off value representing the lowest value for EI:BMR(est) that could, within defined bounds of statistical probability, reflect the habitual energy expenditure of a sedentary life-style. Mean EI:BMR(est) was 1.43 (0.19) compared with an expected requirement of 1.55. In 46 out of the 68 groups (68%), EI:BMR(est) was below the study-specific cut-off value. EI:BMR(est) was 1.37 (SD = 0.13) for women and 1.50 (SD = 0.16) for men (P less than 0.001). This could reflect either better reporting by men or a more active life-style. When categorized according to dietary assessment method, 64%, 88% and 25% of results fell below the acceptable cut-off value for studies by diet records, diet recall and diet history, respectively. These data indicate that dietary assessment methods have a strong bias towards underestimation of habitual energy intake.

Adolescent↗
PubMed1991

Inter-observer variability in the measurement of body composition.

The inter-observer variation in simple bedside assessments of body composition has been evaluated in 12 healthy adult subjects (6 male and 6 female) by 6 observers. Systematic bias between observers was found to be evident in each of the basic measurements (except height) and in each of the estimates of body composition (except those derived from weight and height alone). The largest residual coefficients of variation (rCV) for the basic measurements were found for skinfold thickness (11-18 per cent for individual skinfold thicknesses, and 9 per cent for the sum of four skinfold thicknesses), and the lowest for weight (0.01 per cent for digital scales, and 0.05 per cent for beam balance) and height (0.4 per cent). The rCV for whole-body resistance (1.2 per cent), forearm resistance (5.4 per cent) and near infra-red interactance (optical density 1: 5.6 per cent and optical density 2: 6.2 per cent) measurements were found to have intermediate values. The variability in the estimate of body fat obtained by skinfold thickness (rCV = 4.6 per cent) and near infra-red interactance methods (rCV = 4.2 per cent) was found to be greater than that from the resistance method (rCV = 2.6 per cent) and by methods based on weight and height alone (rCV = 1.1 per cent). The variability in the estimate of fat-free mass showed the same trend as that for body fat, but the rCVs were less due to the greater mass of the fat-free body compared to body fat.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Effects of weight cycling caused by intermittent dieting on metabolic rate and body composition in obese women.

The effects of repeated periods of weight loss and regain on metabolic rate and body composition were investigated in 11 obese women (mean weight 81.98 kg, height 1.61 m, body mass index 31.44 kg/m2) studied for 18 weeks through three consecutive cycles of 2 weeks dieting followed by 4 weeks ad libitum eating. Weight loss was achieved by a very low energy diet (1861 kJ/day). Basal metabolic rate (BMR) was measured by whole-body indirect calorimetry and body composition by a variety of standard in vivo methods. During the three diet periods mean weight losses were 4.44, 3.29 and 2.98 kg although the mean overall weight loss from week 0 to 18 was only 5.93 kg. The proportion of weight lost as fat was estimated as between 67 and 105 per cent of the weight lost depending on the body composition methodology employed. Absolute BMR decreased in response to dieting by 545, 285 and 286 kJ/day. When corrected for body weight and FFM only the decreases in the first diet period were significant (P less than 0.05 and P less than 0.001 respectively). BMR had returned to normal following each 4-week ad libitum period and by the end of the study absolute BMR and BMR/kg FFM had not changed significantly, despite a significant loss of weight. Consequently BMR/kg was increased (P less than 0.01), indicative of the loss of adipose tissue. We have found no evidence in this group of obese women that weight cycling leads to a progressive decrease in BMR or increase in the proportion of body fat.

Adipose Tissue↗