A longitudinal study of urinary calcium, magnesium, and zinc excretion in lactating and nonlactating postpartum women.

Postpartum lactating (n = 12) and nonlactating (n = 11) women and never pregnant women (n = 14) collected urine samples and diet records 2 d each month for 6 mo to determine whether postpartum women conserved urinary calcium, magnesium, or zinc. Mean daily excretions were analyzed by repeated-measures analysis of variance and covariance to assess group and time effects. Lactating women excreted less urinary calcium (1-6 mo) than never pregnant (n = 8) and nonlactating (n = 4) women who did not use oral contraceptives (P < 0.01); however, excretion rose (P < 0.05) by 3 mo postpartum. In the nonlactating and never pregnant groups, women using oral contraceptives excreted less urinary calcium than the other women (P < 0.01). Lactating women excreted less urinary zinc (1-6 mo) than did control and non-lactating women (P < 0.01). Mechanisms may possibly be operating during lactation that depress urinary calcium for > or = 2 mo and urinary zinc < or = 6 mo postpartum.

Value of total body potassium in assessing the nutritional status of children with end-stage liver disease.

Malnutrition is a common problem in children with end-stage liver disease (ESLD), and accurate assessment of nutritional status is essential in managing these children. In a retrospective study, we compared nutritional assessment by anthropometry with that by body composition. We analyzed all consecutive measurements of total body potassium (TBK, n = 186) of children less than 3 years old with ESLD awaiting transplantation found in our database. The TBK values obtained by whole body counting of 40K were compared with reference TBK values of healthy children. The prevalence of malnutrition, as assessed by weight (weight Z score < -2) was 28%, which was significantly lower (chi-square test, p < 0.0001) than the prevalence of malnutrition (76%) assessed by TBK (< 90% of expected TBK for age). These results demonstrated that body weight underestimated the nutritional deficit and stressed the importance of measuring body composition as part of assessing nutritional status of children with ESLD.

Effect of blood transfusions on immune function. III. Alterations in macrophage arachidonic acid metabolism.

Blood transfusions have been shown to prevent allograft rejection, to increase the rate of tumor growth, and to increase susceptibility to infectious complications. We evaluated the mechanism of this immunosuppression by studying the effect of transfusions on macrophage function in a Lewis rat model. Allogeneic transfusions were found to decrease macrophage migration in response to inflammatory stimuli and to increase their production of the strongly immunosuppressive arachidonic acid metabolite prostaglandin E. Syngeneic transfusions did not alter macrophage migration or arachidonic acid metabolism. The immunosuppression seen following transfusions appears to be related to an increased synthesis of prostaglandin E.

Metabolic and immune effects of dietary arginine supplementation after burn.

The effect of supplemental dietary arginine on metabolism and immunity was studied in 36 burned guinea pigs (30% of total body surface area) with previously placed catheter gastrostomies. The animals were randomized into four groups. After an initial three-day adaptation period, all groups received continuous isonitrogenous, isocaloric (175 kcal [735 kJ]/kg/d), and isovolemic intragastric tube feedings until postburn day (PBD) 14. Groups A, B, C, and D received 0%, 1%, 2%, and 4%, respectively, of total energy intake as arginine given in the form of crystalline arginine hydrochloride with 22%, 21%, 20%, and 18%, respectively, of total energy as whey protein. The average body weight after burn decreased equally in all groups. Resting metabolic expenditure on PBD 6 was higher in groups B (151% +/- 6% of preburn) and C (156% +/- 7%) than in groups A (131% +/- 4%) and D (136% +/- 3%). Ear-thickness response to dinitrofluorobenzene challenge on PBD 12 showed the best response in group C. The mortality rates of groups A, B, C, and D were 56%, 29%, 22%, and 56%, respectively. This study suggests that oral dietary arginine supplementation up to 2% of energy intake may be beneficial after burn injury.

An evaluation of the use of total body electrical conductivity for the estimation of body composition in adult rats: effect of dietary obesity and adrenalectomy.

Total body electrical conductance (TOBEC) has been recommended for serial measurements of body composition in animals and humans. This study examined the accuracy of the TOBEC technique in predicting body composition of a population of adult male rats that had undergone seven different treatments, including adrenalectomy and blocking of glucocorticoid receptors, in the study of the etiology of obesity. The predicted body composition values of the animals (n = 57, body weight 550 +/- 8 g) obtained by using the manufacturer's and Baer's equations were compared to the actual body composition obtained by direct carcass analysis. Both equations underestimated lean body mass and reciprocally overestimated body fat (manufacturer's 103 +/- 4 g, Baer's 55 +/- 3 g). A new prediction equation was developed based on the conductivity index and the actual lean body mass. This revised equation was able to accurately estimate the lean body mass of the animals used in the same experiment but over-estimated lean body mass of larger animals (n = 10, wt. 647 +/- 13 g). Conclusions based on multiple comparisons (Duncan's) of predicted and actual values resulted in different effects of treatments on body composition. To improve accuracy and reliability of the TOBEC technique, a prediction equation should be developed from the same population as the studied population, and experimental group sizes used for examining treatment effects should be relatively large.

Comparison of measured sleeping metabolic rate and predicted basal metabolic rate during the first year of life: evidence of a bias changing with increasing metabolic rate.

OBJECTIVE: To compare measurements of sleeping metabolic rate (SMR) in infancy with predicted basal metabolic rate (BMR) estimated by the equations of Schofield. METHODS: Some 104 serial measurements of SMR by indirect calorimetry were performed in 43 healthy infants at 1.5, 3, 6, 9 and 12 months of age. Predicted BMR was calculated using the weight only (BMR-wo) and weight and height (BMR-wh) equations of Schofield for 0-3-y-olds. Measured SMR values were compared with both predictive values by means of the Bland-Altman statistical test. RESULTS: The mean measured SMR was 1.48 MJ/day. The mean predicted BMR values were 1.66 and 1.47 MJ/day for the weight only and weight and height equations, respectively. The Bland-Altman analysis showed that BMR-wo equation on average overestimated SMR by 0.18 MJ/day (11%) and the BMR-wh equation underestimated SMR by 0.01 MJ/day (1%). However the 95% limits of agreement were wide: -0.64 to +0.28 MJ/day (28%) for the former equation and -0.39 to +0.41 MJ/day (27%) for the latter equation. Moreover there was a significant correlation between the mean of the measured and predicted metabolic rate and the difference between them. CONCLUSIONS: The wide variation seen in the difference between measured and predicted metabolic rate and the bias probably with age indicates there is a need to measure actual metabolic rate for individual clinical care in this age group.

Effects of fish oil on postburn metabolism and immunity.

The metabolic effects and immune responses of different levels of fish oil in enteral formulas for postburn nutritional support were studied. Thirty-seven burned guinea pigs with previously placed gastrostomy feeding tubes were given diets containing 5, 15, 30, or 50% of nonprotein calories as fish oil. These diets were isonitrogenous, isocaloric, and contained identical amounts of vitamins and minerals. After 14 days of enteral feeding, there were no significant differences in resting metabolic expenditure, serum transferrin, and albumin levels. Weight loss was significantly greater in groups receiving 30 and 50% of fish oil compared to groups which received 5 and 15% of fish oil. Carcass weights and liver weights of animals in the two groups that received diets with higher lipid content were also significantly lower. Cell-mediated immunity, macrophage bactericidal indices, and opsonic indices were not different among the groups. This study confirms that diets containing lower levels of lipids are more effective for enteral nutritional support than those containing higher levels. In contrast to linoleic acid rich lipid sources, higher levels of fish oil did not show adverse effects on immunity possibly because it contained high concentrations of omega 3 fatty acids which are not precursors of immunosuppressive prostaglandin E2.

Intact protein versus free amino acids in the nutritional support of thermally injured animals.

This study compared the nutritional effects of intact protein with that of constituent amino acids as the sole source of nitrogen in a burn guinea pig model. Forty-five guinea pigs bearing a gastrostomy feeding tube were given 30% total body surface area, full thickness flame burn and were randomized into four groups. Group I (n = 12) and group III (n = 15) received a diet containing whey protein, while group II (n = 9) and group IV (n = 9) received an otherwise identical diet containing free amino acids in a whey protein pattern. Full strength continuous intragastric feeding was initiated immediately postburn in groups I and II, but a 72-hr adaptive period was provided in groups III and IV. Resting metabolic expenditure was measured by indirect calorimetry on postburn days 2, 6,9, and 13. After 14 days of enteral feeding, the animals were killed. Immediate enteral feeding of intact protein or free amino acids reduced postburn hypermetabolic response (p less than 0.01). However, the intact protein was found to maintain body weight and provide nitrogen retention better than the amino acid mixture (p less than 0.05). The animals on the intact protein diet also showed statistically significant benefits in carcass, liver, and gastrocnemius muscle weights and in serum albumin, transferrin and C3 levels. It is concluded that intact protein is superior to free amino acids for nutritional support following burn injury.

Prevention of yeast translocation across the gut by a single enteral feeding after burn injury.

Recently, burn injury has been shown to facilitate the ability of enteric Candida albicans (CA) to penetrate the gut epithelium and translocate to the mesenteric lymph nodes (MLN) during the first 24 hr after injury. Guinea pigs were given 3 X 10(10) CA intragastrically before inflicting a 50% burn to determine if a single enteral feeding could affect CA translocation to the MLN. A bolus infusion (20 kcal/kg, 12 ml in volume) of liquid meal, consisting of 68% carbohydrate, 20% protein, and 12% lipid, was administered either at 3-hr or 12-hr postburn. Control groups received no food or a similar amount of saline by bolus infusion. All animals were allowed water ad libitum until 24-hr postburn when their MLN and intestinal segments were harvested for enumeration of viable CA. Blood was also collected for determination of serum IgG, C3, cortisol, and albumin. Compared to nonfeed animals, those with a single enteral feeding at 12-hr postburn had reduced numbers of CA translocating to the MLN (970 +/- 220 vs 7,120 +/- 2,130 CFU/g, p less than 0.02) and colonizing in the ileum (27,000 +/- 6,770 vs 104,000 +/- 23,550 CFU/g, p less than 0.01). Bolus feeding at 12 hr was associated with a lower cortisol level (237 +/- 55% of normal controls) than bolus feeding at 3 hr (310 +/- 58, p less than 0.02) or the nonfed group (326 +/- 66, p less than 0.01). Regardless of dietary treatment, serum cortisol levels correlated positively with the extent to which CA translocated to the MLN and negatively with C3 levels.

The effect of route of nutrient administration on the nutritional state, catabolic hormone secretion, and gut mucosal integrity after burn injury.

So that the efficacy of route of nutrient administration in thermal injury could be determined, a comparison was made between immediate enteral vs parenteral feedings in burned guinea pigs. Thirty-five guinea pigs underwent both catheter gastrostomy and jugular vein catheterization. On postoperative day 8, burned animals [30% total body surface area (TBSA)] were divided into an intragastrically (ig) fed group (N = 14) and a parenterally (iv) fed group (N = 14). Animals in each group received 175 kcal/kg/day with a solution of identical nutrient value beginning 2 hr after burn. The body weight change until postburn day (PBD) 8 and the average nitrogen balance were significantly better in the ig group than in the iv group. Values were also higher for the iv group than for the ig group in the early postburn period for urinary vanillyl mandelic acid (VMA) (p less than 0.05), plasma cortisol (p less than 0.05), and plasma glucagon (p less than 0.05). Also, the iv group showed reduced mucosal weight and thickness compared to the ig group on PBD 1 (p less than 0.02). There were significant negative correlations between VMA excretion and body weight change, and between plasma cortisol and jejunal mucosal structure (thickness and weight). These findings suggest that immediate postburn enteral nutrition can provide better nutritional support than parenteral nutrition through the maintenance of gut mucosal integrity and the prevention of increased secretion of catabolic hormones.

Optimal lipid content for enteral diets following thermal injury.

This study was performed to determine the effects of different amounts of lipid in enteral diets during the postburn period. Forty-five guinea pigs with catheter gastrostomy received a 30% total body surface area full thickness flame burn. After burn they were given intragastric tube feedings using five diets at different dietary lipid composition: 0, 5, 15, 30, and 50% of nonprotein calories. Total calories administered (175 kcal/kg/day), protein content and composition (20% of total calories), total volume, and vitamin and mineral content were constant in all animals. At postburn day 14, body weight, carcass weight, and muscle weight were the greatest in 0 and 5% lipid groups, and the least in 30 and 50% lipid groups. Serum transferrin was highest in the 5 and 15% lipid groups, and lowest in the 30 and 50% lipid groups. Total nitrogen content in muscle and cumulative nitrogen balance were best in the 15% lipid group. Liver fatty infiltration, caused from a larger proportion of carbohydrate administration, was greater in the 0 and 5% lipid groups and less in 15 and 30% groups. It is concluded that dietary lipid levels between 5 and 15% of nonprotein calories are optimal for nutritional support after burn injury. The nutritional management of postburn patients with higher levels of dietary lipid should be reconsidered.

Enteral feeding in burn hypermetabolism: nutritional and metabolic effects of different levels of calorie and protein intake.

Enteral nutrition was provided by continuous pump-controlled gastrostomy tube feeding for 14 days in 97 guinea pigs bearing a 30% full thickness burn. Seven defined combinations of caloric and protein intake were studied. With a caloric intake of 175 kcal/kg/day, equaling the measured energy expenditure, the animals receiving 10% of calories as protein had a significantly greater postburn weight loss (p less than 0.05) and muscle mass depletion (p less than 0.05), and a significantly lower muscle nitrogen concentration (p less than 0.05), serum albumin level (p less than 0.01) and liver nitrogen content (p less than 0.01). With the same caloric intake but with more than 20% of calories as protein, the weight loss and the muscle wasting were reduced, but not abolished, and the serum albumin level and liver nitrogen content were normalized. Also with the diets containing 200 kcal/kg/day the muscle tissue depletion could not be abolished. However, with this caloric intake, the animals given 20% of calories as protein had a lower weight loss and a higher serum albumin level (p less than 0.01), but also a greater fat infiltration of the liver (p less than 0.01). At both levels of caloric intake, the nitrogen balance correlated significantly with the level of nitrogen intake but did not correlate with the changes of body weight. The incidence of diarrhea was lowest in animals fed 20% protein calories at a caloric intake of 175 kcal/kg/day. All things considered, the best metabolic and nutritional results were obtained with diets containing 20 to 30% of calories as protein and providing a caloric intake that paralleled the measured energy expenditure.

Evaluation of early enteral feeding in children less than 3 years old with smaller burns (8-25 per cent TBSA).

Early enteral feeding and high protein nutrition have been advocated for burned patients. The safety and efficacy of early high protein nasogastric feeding (NG) have not been evaluated in very young children. The present study evaluated such feeding in children less than 3 years old with smaller burns (8-25 per cent of total body surface area). Children (n = 10) were able to tolerate high protein intake without detrimental effects. The incidences of gastrointestinal complications related to NG feeding were low. The children needed approximately 2 weeks of supplemental NG feeding which provided two-thirds of total energy intake and three-fourths of protein intake. In spite of smaller burns, the mean measured resting metabolic expenditure (REE) was 1.3 x predicted REE. The mean energy intake of 92 per cent of recommended daily allowances (RDA) for energy or 1.7 x predicted REE was able to maintain body weight. The mean protein intake was 4.3 g/kg/day with a non-protein calorie ratio of 114:1. During the first week postburn, plasma concentrations of prealbumin, albumin and transferrin were low. The high protein intake was able to raise these visceral proteins to normal ranges. These results indicate that early NG feeding is safe and efficacious for achieving increased energy intake and improved protein status in very young children.

Effect of vitamin A in enteral formulae for burned guinea-pigs.

A burned guinea-pig model (30 per cent body surface area) was used to study the effects of dietary vitamin A. Sixty-five female guinea-pigs were infused enterally via gastrostomy feeding tubes with identical formulate (175 kcal/kg/day, 20 per cent of calories as protein) containing varying amounts of vitamin A. Groups I, II, III and IV received formulae containing 0, 10,000 iu (approximately equivalent to the guinea-pigs' RDA), 50,000 iu (5 x RDA) and 250,000 iu (25 x RDA) of vitamin A per litre, respectively. After 14 days of tube feeding, the animals were killed. Group I animals had evidence of vitamin A deficiency including low haemoglobin levels, lower red blood cell counts and lower caecal mucosal weight. Findings of hypervitaminosis A were observed only in animals given the highest dose of vitamin A (25 x RDA). These were elevated serum alkaline phosphatase and complement C3 levels and enlarged adrenal glands. Group IV also showed defective cell-mediated immunity as reflected by reduced delayed cutaneous response to dinitrofluorobenzene. In a second experiment groups I, II, III and IV were given formulas containing 0, 1 x RDA, 5 x RDA, and 10 x RDA of vitamin A respectively for 14 days. Through postburn days 12 to 14 they were injected subcutaneously with 3 x 10(8) of Staphylococcus aureus once daily. On postburn day 15 the animals were killed and the numbers of viable bacteria at each injection site were counted. No significant differences were observed in viable bacterial numbers between the groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Increased gut blood flow with early enteral feeding in burned guinea pigs.

The hemodynamic responses to early enteral feeding were assessed with fluid-resuscitated, 30% total body surface area-burned guinea pigs fed by means of tube gastrostomies. Regional blood flow and cardiac output were determined by a reference sample method, injecting 15 microns radiolabeled microspheres. During the initial 24 hours after burn injury, animals were given the same volume by continuous infusion of either lactated Ringer's solution (LR group) or a liquid diet (20% protein, 12% lipid, and 68% carbohydrate; 175 kcal/kg/24 hr) (diet group). Although cardiac outputs in the LR and diet groups were not different from each other at 24 hours and no less than that in unburned control animals, the diet group showed higher blood flow to the jejunum (+55.7%) and cecum (+98.7%) than did the LR group. Burn injury caused little change of blood flow to tissues other than the intestine. In addition, early feeding after burn injury suppressed excessive cortisol response to burn shock. The increase in gut blood flow associated with enteral feeding could have an impact on mucosal barrier function.