We have recently found that an impairment of the wound healing response (WHR) occurs in surgical patients with protein-energy malnutrition before there are any measurable changes in body fat and protein stores. The hypothesis of this study was that the patients' recent food intake is more important in determining the WHR than the patients' overall nutritional status. We have measured the recent food intake (by dietary recall), the WHR (by hydroxyproline accumulation in subcutaneous GORE-TEX implants), the pre-operative weight loss (per cent), and body fat and protein stores (by in vivo neutron activation analysis) in 83 patients awaiting a major elective gastrointestinal resection, and divided them into two groups: adequate recent food intake (n = 59) and inadequate recent food intake (n = 24). There was no significant difference between these two groups for age, sex, diagnosis, surgical procedure, weight loss (per cent), or the amount of body fat and protein stores but there was a significant difference in the WHR (1.81 +/- 0.16 s.e.m. versus 1.04 +/- 0.22 s.e.m. nmol hydroxyproline/mg GORE-TEX, P less than 0.005). These results show that pre-operative food intake has a greater influence over the wound healing response than absolute losses of protein and fat from body stores and they suggest that the maintenance of a normal food intake up until the time of surgery is of importance in preventing an impairment of the wound healing response.

In vivo neutron activation analysis (NAA) is currently used to measure body composition in metabolic and nutritional studies in many clinical situations, but has not previously been validated by comparison with chemical analysis of human cadavers. Total body nitrogen (TBN) and chlorine (TBCl) were measured in two human cadavers by NAA before homogenization and chemical analysis (CHEM) after (cadaver 1: TBN, 1.47 NAA, 1.51 CHEM; TBCl, 0.144 NAA, 0.147 CHEM; cadaver 2: TBN, 0.576 NAA, 0.572 CHEM; TBCl, 0.0227 NAA, 0.0250 CHEM). The homogenates were also analyzed by NAA, and no significant differences were found, indicating that the effects of elemental inhomogeneity on the measurement of TBN and TBCl are insignificant. Total body water, fat, protein, minerals, and carbohydrates were measured chemically for each cadaver and compared with estimates for these compartments obtained from a body composition model, which when used in vivo involves NAA and tritium dilution. The agreement found justifies the use of the model for the measurement of changes in total body protein, water, and fat in sequential studies in groups of patients.

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Prompt gamma neutron activation analysis with 238Pu/Be sources is used to measure total body chlorine (TBCl) in vivo following the reaction 35Cl(n, gamma)36Cl. The chlorine de-excitation at 8.57 MeV is used for calibration of the system for TBCl. Body hydrogen is used as an internal standard and TBCl is derived from the gamma-ray counts ratio of chlorine to hydrogen. The precision of the method, determined from replicate scans of a Bush-type phantom, is 4.9% (CV). To assess accuracy an anthropomorphic phantom consisting of minced meat was constructed. Replicate scans of this phantom yielded a mean total chlorine which was not significantly different from the chemical analysis value. The subject dose equivalent for the activation measurement is less than 0.3 mSv. Mean TBCl values for 63 male and 107 female healthy volunteers were in broad agreement with predicted amounts based on multiple regression equations developed at other centres from measurements using the delayed gamma approach. Good agreement was observed in 76 volunteers between total body water (TBW) measured by tritium dilution, after correction for non-aqueous hydrogen exchange, and TBW derived from the sum of extracellular water and intracellular water as measured by TBCl and total body potassium (TBK), respectively.

The risks of forming uric acid stones are high for both ileostomy and J-pouch patients, but our results suggest that there will be a reduction in calcium stone formation after J-pouch.