Expression of DNA methyltransferases in the mouse uterus during early pregnancy and susceptibility to dietary folate deficiency

We have characterized the uterine expression of DNA methyltransferases (DNMTs) during early pregnancy in mice and determined whether a folate-deficient diet (FDD) can affect DNMTs in this context. Within endometrial cells, expressions of DNMT (cytosine-5) 1 (Dnmt1), Dnmt3a, and Dnmt3b were significantly elevated during the prereceptive phase of pregnancy but generally returned to baseline levels during receptive and postimplantation periods. As such, the transcription of DNMT genes is temporally regulated during early pregnancy. When comparisons were made between implantation sites (IS) and inter-IS on day 5 of pregnancy, lower levels of Dnmt3a were detected at IS. Comparisons between IS and inter-IS did not reveal significant expression differences for other DNMT genes. When tissue sections were examined, DNMT3A was specifically lower in the stroma of IS. Reduced DNMT1 and DNMT3B levels were also observed in the luminal and glandular epithelia of IS, whereas no obvious differences in the stroma were detected. In pseudo-pregnant mice subjected to a FDD, levels of Dnmt1 and Dnmt3a (but not Dnmt3b) were significantly upregulated in endometrial tissues, as compared with controls. When tissues from these folate-deficient mice were examined, DNMT1 levels were elevated in both the luminal and glandular epithelia, whereas DNMT3A was upregulated in the luminal epithelium and the stroma. A slight increase in DNMT3B levels was detected in the glandular epithelium. These results indicate that DNMTs may regulate the transcription of endometrial genes associated with embryo implantation and that levels of DNMTs are affected by dietary folate in mice.

Ascorbic acid dynamics in the seriously ill and injured

BACKGROUND

In addition to the known beneficial effects of ascorbic acid on wound healing and the immune response, it is also a potent extracellular antioxidant. Recent work in septic rats suggests that high-dose ascorbic acid total parenteral nutrition (TPN) supplementation may protect cells from free radical injury and improve survival. In this study, we determined ascorbic acid levels in the immediate post-injury/illness period and evaluated the ability of early short-term high levels of ascorbic acid in TPN to normalize plasma levels.

MATERIALS AND METHODS

Ascorbic acid levels were determined in 12 critically injured patients and 2 patients with severe surgical infections. Each patient received TPN supplemented with increasing doses of ascorbic acid over a 6-day period. Therapeutic responses were determined by plasma and urine measurements using high-pressure liquid chromatography.

RESULTS

The initial mean +/- SEM baseline plasma ascorbic acid concentration was depressed (0.11 +/- 0.03 mg/dl) and unresponsive following 2 days on 300 mg/day supplementation (0.14 +/- 0.03; P = 1.0) and only approached low normal plasma levels following 2 days on 1000 mg/day (0.32 +/- 0.08; P = 0.36). A significant increase was noted following 2 days on 3000 mg/day (1.2 +/- 0.03; P = 0.005).

CONCLUSION

We confirmed extremely low plasma levels of ascorbic acid following trauma and infection. Maximal early repletion of this vitamin requires rapid pool filling early in the post-injury period using supraphysiologic doses for 3 or more days.

Gastric emptying in trauma patients

BACKGROUND/AIM

The aim of this study was to obtain quantitative data on gastric emptying following trauma.

METHODS

In order to assess gastric emptying for early enteral feeding, we evaluated the absorption of an amino acid, L-[1-(13)C]phenylalanine, within 24 h of admission and 7 days later in 14 trauma patients (injury severity score 36 +/- 2). Following nasogastric administration of 100 mg L-[1-(13)C]phenylalanine, the plasma L-[1-(13)C]phenylalanine enrichment at 30 and 60 min and the expired (13)CO(2) for 1 h in the breath were used to measure the degree of gastric emptying.

RESULTS

The plasma L-[1-(13)C]phenylalanine enrichment concentration at 30 min was 0.53 +/- 0.23 mmol/l during the first study and 2.46 +/- 0. 62 mmol/l during the second study (p = 0.006, a fivefold increase). The L-[1-(13)C]phenylalanine plasma level in historic controls was 4. 57 +/- 1.48 mmol/l. The percent of the dose oxidized and expired as (13)CO(2) in 1 h was 0.51 +/- 0.17 during the first 24-hour study compared to the second study of 3.37 +/- 0.68 (p = 0.0008) 7 days later (an over sixfold increase). The percent of the dose oxidized in 1 h in 37 normal historic controls was 7.08 +/- 0.33.

CONCLUSION

These data indicate delayed gastric emptying with limited recovery in 1 week. We conclude that gastric feeding should not be employed, and the route for early nutritional intervention should be transpyloric for the trauma patient.

[Effects of acute hypoxia and hypoxic acclimatization on cardiac functions of rats]

OBJECTIVE

To study the effects of acute hypoxia and intermittent hypoxic acclimatization on cardiac systolic and diastolic functions in rats.

METHOD

Cardiac functions were investigated after intermittent hypoxic acclimatizated (3000 m and 5000 m, 2 wk respectively, 4 h/d) and normoxic rats were exposed to hypoxia (8000 m) for 4 h.

RESULT

The systolic functional parameters such as LVSP, +dp/dtmax, Vpm, Vmax and the diastolic functional parameter -dp/dtmax of acute hypoxic rats were reduced significantly as compared with normoxic control rats. After hypoxic acclimatization, the left ventricular functions of rats were increased significantly as compared with those of acute hypoxic rats. But they were still lower than those of normoxic control rats.

CONCLUSION

Acute hypoxia can affect cardiac functions and hypoxic acclimatization can alleviate the hypoxic effects on cardiac functions.

Insulin's anabolic effect is influenced by route of administration of nutrients

OBJECTIVE

To determine if the anabolic effects of intravenous insulin on protein kinetics could be exploited in the enterally fed trauma victim.

DESIGN

Randomized, crossover control protocol.

SETTING

Level I trauma center.

PATIENTS

Ten trauma patients with an Injury Severity Score higher than 20. Exclusion criteria included diabetes mellitus, pregnancy, steroid use, and aged younger than 18 years or older than 65 years.

INTERVENTIONS

Within the first 24 hours of admission to the intensive care unit, each patient had a transpyloric feeding tube inserted radiographically. Enteral nutrition was provided with a protein supplement (Ensure, Ross Laboratories, Columbus, Ohio) and Promod, supplemented with protein powder to supply 1.5 g/kg per day of protein and 156.9 kJ/kg per day. Intravenous insulin was provided at 0.043 U/kg per hour beginning on the second or fourth day.

MAIN OUTCOME MEASURES

Urinary nitrogen balance and 3-methylhistidine excretion rates were measured at the end of the third and fifth days. Plasma glucose, insulin, and C-peptide levels were obtained at these same times.

RESULTS

Urinary nitrogen balance was not significantly different with or without the administration of insulin (-4.58+/-50.1 mg/kg per day vs -9.38+/-50.9 mg/kg per day, respectively). 3-Methylhistidine excretion rates did not change significantly with or without the administration of insulin (5.77+/-0.67 micromol/kg per day vs 6.15+/-0.43 micromol/kg per day, respectively). Serum insulin levels did not differ significantly when exogenous infusions were added (57.8+/-17.9 microU/mL vs 82.1+/-44.9 microU/mL), but serum C-peptide levels did decrease significantly when exogenous insulin was added (5.11+/-3.2 microU/mL vs 10.28+/-3.5 microU/mL; P = .04). Serum glucose levels decreased significantly when insulin was administered (5.8+/-0.4 mmol/L [104.6+/-7.2 mg/dL] vs 7.7+/-0.4 mmol/L [138.1+/-7.4 mg/dL; P =.004).

CONCLUSION

The anabolic effect of intravenous insulin on protein kinetics is not evident when nutrition is provided enterally in the trauma victim.

Effect of amino acid infusion on glucose production in trauma patients

The relationship between precursor supply and hepatic glucose output (HGO) was examined in 8 control subjects and 12 trauma patients after a fasting period of approximately 60 hours. Glucose kinetics were measured with a primed-constant infusion of [U-14C]glucose and [6-3H]glucose. The basal rate of HGO was 5.45 +/- 0.22 micromol x kg-1 x min-1 in the controls and 13.16 +/- 0.76 micromol x kg-1 x min-1 following trauma (p < 0.001). Four hours after amino acid infusion of 1.3 g x kg-1 x 24 h-1, HGO in the controls was unchanged at 5.35 +/- 0.22 micromol x kg-1 x min-1 but it had decreased to 11.71 +/- 0.67 micromol x kg-1 after trauma (p < 0.001). We conclude that increasing the supply of gluconeogenic precursors does not stimulate HGO in normal subjects after fasting or after severe trauma and that factors other than to availability of amino acids are responsible for the enhanced rate of HGO in trauma patients.

Impact of enteral feeding of a glutamine-supplemented formula on the hypoaminoacidemic response in trauma patients

Plasma amino acid concentrations were measured during fasting and after 3 days of enteral feeding in 16 trauma patients on a glutamine-supplemented diet and 14 patients on an isonitrogenous control diet. During fasting, total amino acids, including glutamine, were depressed by 50% and this was attributed to a reduction in both essential and nonessential amino acids. The essential amino acid concentrations increased in both groups after feeding. The nonessential amino acid concentrations also increased in the control group but not in the glutamine group during feeding. Repletion of the glutamine extracellular pool was not evident after an average intake of 27.1 g per day of glutamine for 3 days. Nitrogen balance was similar for the two groups during feeding. We conclude that in this study, enteral glutamine did not increase the glutamine plasma concentration. In addition, both formulas improved the hypoaminoacidemia of essential amino acids but only the control diet improved the nonessential amino acids plasma concentration.

Glutamine supplementation of enteral nutrition: impact on whole body protein kinetics and glucose metabolism in critically ill patients

BACKGROUND

Glutamine-supplemented parenteral nutrition has been reported to attenuate the early postoperative reduction in intracellular glutamine and improve protein synthesis and nitrogen balance. We investigated the effect of an enteral formula or protein and glucose kinetics and nitrogen balance in trauma patients.

METHODS

The enteral formula (AlitraQ) provided a mean intake of 0.35 g of glutamine/kg body weight per day to 16 trauma patients and was compared with an isonitrogenous formula that provided a mean of 0.05 g of glutamine/kg body weight per day in 14 trauma patients. After 3 days of feeding, protein kinetics were measured using a 4-hour prime-continuous infusion of L-[1-13C]leucine. Glucose kinetics were measured during the same time interval using prime-continuous infusion of [U-14C]- and [6-3H]glucose.

RESULTS

Nitrogen balance was not significantly different in the two groups. There were no significant differences in protein turnover, synthesis, and breakdown between the two groups. There were no significant differences in glucose turnover, oxidation, recycling, and percent of VCO2 from glucose oxidation between the two groups.

CONCLUSIONS

Glutamine-enriched enteral formulas are well tolerated by the severely injured patient but provide no additional nutritional advantage compared with standard enteral formulas during the first 3 days of feeding immediately after trauma.

Protein and energy balance following femoral neck fracture in geriatric patients

To elucidate the effect of total peripheral parenteral nutrition (TPPN) on protein kinetics following injury, we compared the whole-body leucine kinetic response using a primed-constant infusion of L-[1-14C]leucine in 33 elderly patients (aged 82 +/- 1.0 years) following hip fracture and 33 healthy elderly control subjects (aged 75 +/- 0.7 years). Following a 36-hour fast, leucine release from protein breakdown was 1.2 +/- 0.10 mumol.kg-1.min-1 and leucine incorporation into protein was 0.94 +/- 0.095 mumol.kg-1.min-1 in control subjects, and in injured subjects leucine release from protein breakdown was 1.3 +/- 0.14 mumol.kg-1.min-1 and leucine incorporation into protein was 0.97 +/- 0.092 mumol.kg-1.min-1. Control and injured subjects were then administered TPPN (protein, 1.5 g amino acids.kg-1; carbohydrate, 10.0 kcal.kg-1; lipid, 15.0 kcal.kg-1) for 24 hours, and leucine kinetics were redetermined. Compared with protein kinetics in the fasting state, leucine release from protein decreased to 1.0 +/- 0.14 mumol.kg-1.min-1 and leucine incorporation into protein increased to 1.16 +/- 0.097 mumol.kg-1.min-1 in control subjects. Injured patients also responded to TPPN with a decrease in leucine release from protein breakdown (1.12 +/- 0.156 mumol.kg-1.min-1) and an increase in leucine incorporation into protein (1.29 +/- 0.164 mumol.kg-1.min-1). These results indicate that in a geriatric population, whole-body leucine kinetics following hip fracture and the anabolic response to TPPN are not significantly altered from those of uninjured subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Deletion mapping of four loci defined by N-ethyl-N-nitrosourea-induced postimplantation-lethal mutations within the pid-Hbb region of mouse chromosome 7

As part of a long-term effort to refine the physical and functional maps of the Fes-Hbb region of mouse chromosome 7, four loci [l(7)1Rn, l(7)2Rn, l(7)3Rn, l(7)4Rn] defined by N-ethyl-N-nitrosourea (ENU)-induced, prenatally lethal mutations were mapped by means of trans complementation crosses to mice carrying lethal deletions of the mouse chromosome-7 albino (c) locus. Each locus was assigned to a defined subregion of the deletion map at the distal end of the Fes-Hbb interval. Of particular use for this mapping were preimplantation-lethal deletions having distal breakpoints localized between pid and Omp. Hemizygosity or homozygosity for each of the ENU-induced lethals was found to arrest development after uterine implantation; the specific time of postimplantation death varied, and depended on both the mutation itself and on whether it was hemizygous or homozygous. Based on their map positions outside of and distal to deletions that cause death at preimplantation stages, these ENU-induced mutations identify loci, necessary for postimplantation development, that could not have been discovered by phenotypic analyses of mice homozygous for any albino deletion. The mapping of these loci to specific genetic intervals defined by deletion breakpoints suggests a number of positional-cloning strategies for the molecular isolation of these genes. Phenotypic and genetic analyses of these mutations should provide useful information on the functional composition of the corresponding segment of the human genome (perhaps human 11q13.5).

Protein turnover in advanced lung cancer patients

Understanding the extent to which changes in whole-body protein kinetics contribute to the commonly observed weight loss and decrease in lean body mass (LBM) in patients with cancer is currently obscured by conflicting reports in the literature. While several studies have reported significant increases in whole-body protein turnover (WBPT), synthesis (WBPS), and catabolism (WBPC) in patients with cancer, others have failed to confirm these observations. We have measured whole-body protein kinetics using a primed constant infusion of 15N-glycine in a homogenous group of 32 newly diagnosed advanced lung cancer patients with comparable staging and before any antineoplastic treatment, and in 19 normal healthy volunteer controls. Urinary urea and ammonia 15N enrichment was determined in individually collected urine samples obtained during the 24-hour study period and averaged for the determination of protein kinetics. During the last 6 hours of urine collection, samples were obtained hourly for determination of 15N plateau enrichment. Twenty-four-hour urinary nitrogen and creatinine excretion was determined from 24-hour pooled urine samples. Resting metabolic expenditure (RME) was determined by indirect calorimetry and LBM was estimated from deuterium oxide dilution. Age body weight, LBM, RME, and 24-hour urinary nitrogen excretion did not differ between cancer and control subjects. WBPT, WBPC, and WBPS (g/kg/d) were significantly increased in lung cancer patients. However, when the same results were expressed either per kilogram LBM or per gram 24-hour urinary creatinine excretion, WBPT, WBPC, and WBPS rates were not statistically different from those of the controls.(ABSTRACT TRUNCATED AT 250 WORDS)

[Estimation of energy expenditure in clinical practice: applicability to individual multiple injury cases]

In 37 multiple trauma patients the estimated and measured energy expenditures were compared. Predicted energy expenditure overestimated it in 89% of patients. The correction factor for the different pathologies was the principal source of error, since the measured/predicted basal energy expenditure ratio was 1.19 +/- 0.17. This ratio had a wide range of values (0.84-1.61) which renders the prediction of individual energy expenditure highly unreliable. Since the overestimation of energy requirements in the critically ill patients may convey important complications, the direct measurement of such requirements is recommended.

Prediction of resting energy expenditure from fat-free mass and fat mass

On the basis of literature values, the relationship between fat-free mass (FFM), fat mass (FM), and resting energy expenditure [REE (kJ/24 h)] was determined for 213 adults (86 males, 127 females). The objectives were to develop a mathematical model to predict REE based on body composition and to evaluate the contribution of FFM and FM to REE. The following regression equations were derived: 1) REE = 1265 + (93.3 x FFM) (r2 = 0.727, P < 0.001); 2) REE = 1114 + (90.4 x FFM) + (13.2 x FM) (R2 = 0.743, P < 0.001); and 3) REE = (108 x FFM) + (16.9 x FM) (R2 = 0.986, P < 0.001). FM explained only a small part of the variation remaining after FFM was accounted for. The models that include both FFM and FM are useful in examination of the changes in REE that occur with a change in both the FFM and FM. To account for more of the variability in REE, FFM will have to be divided into organ mass and skeletal muscle mass in future analyses.

Glucose metabolism in advanced lung cancer patients

Although it is generally accepted that altered nutrient intake and metabolism are responsible for the progressive loss of body weight observed in most advanced cancer patients, there is still considerable controversy regarding the contributory role of changes in both resting energy expenditure (REE) and glucose metabolism. Several studies suggest increases in both REE and glucose appearance in advanced cancer patients compared with healthy control subjects, whereas others revealed no changes in either metabolic parameter. We measured REE with indirect calorimetry and glucose kinetics with a primed constant infusion of D-[U-14C]glucose and D-[6-3H]glucose over the last 4 h of a 24-h fast in 32 advanced lung cancer patients immediately after diagnosis and before any chemotherapy or radiotherapy and in 19 healthy volunteer subjects. REE for the lung cancer group was not significantly different from that in the control group (1535.8 +/- 78.0 vs. 1670.2 +/- 53.9 kcal/day, respectively, p = 0.151). When REE was expressed as a function of body weight, or lean body mass, no differences between the two groups were observed. The rate of glucose appearance was 9.88 +/- 0.36 mumol.kg-1.min-1 in the cancer patients and 10.15 +/- 0.53 mumol.kg-1.min-1 in control subjects (p = 0.667), of which 50.4 versus 58.2%, respectively, was oxidized. The amount of glucose recycled was 13.54 +/- 1.22% in cancer patients and 15.08 +/- 0.99% in control subjects (p = 0.394). The amount of VCO2 from direct oxidation of glucose was 23.39 +/- 0.74% in cancer patients and 27.45 +/- 1.36% in control subjects (p = 0.006).(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma amino acid concentrations in geriatric control and hip-fracture patients

Changes in plasma amino acids, 24-h nitrogen balances, and resting metabolic expenditures (RMEs) were measured in 10 geriatric patients (aged 70-92 y) with hip fracture 1 d after surgical fixation during both a 24-h fasting state and while receiving total peripheral parenteral nutrition (TPPN) for 24 h at 1.5 g amino acids.kg-1.d-1 and 29-30 kcal.kg-1.d-1 and compared with 19 healthy volunteer subjects (aged 70-84 y). RME and 24-h urinary nitrogen losses were also elevated in the trauma patients during both fasting and TPPN. Positive nitrogen balances were evident in both groups during TPPN. Plasma total amino acid concentration was significantly lower in the trauma patients because of lower plasma concentrations of the nonessential amino acids. Phenylalanine and methionine concentrations were significantly higher and lysine lower in the trauma group. In addition, evaluation of the essential amino acid ratios after fasting and TPPN reveal that there are no limiting amino acids during TPPN.

Effect of weight reduction on resting energy expenditure, substrate utilization, and the thermic effect of food in moderately obese women

It is not known whether the decrease in the thermic effect of food (TEF) in obesity is a consequence of obesity or a factor contributing to the development of obesity. The resting energy expenditure (REE) of 24 obese, nondiabetic, postmenopausal women was 5481 +/- 110 kJ/24 h (1310 +/- 26.4 kcal/24 h). After weight loss (12.7 +/- 0.45 kg) the REE was significantly decreased (4858 +/- 94 kJ/24 h, or 1161 +/- 22.4 kcal/24 h) and equivalent to the REE of 4866 +/- 119 kJ/24 h (1163 +/- 28.5 kcal/24 h) in 24 never-obese, postmenopausal women. The TEF, expressed as a percentage of the calories ingested, was 8.2 +/- 0.50% for obese subjects, 8.7 +/- 0.57% for postobese subjects, and 9.8 +/- 0.54% for never-obese subjects. Compared with never-obese subjects, the TEF was significantly reduced in obese subjects (P = 0.043) and remained unchanged after weight loss (P = 0.341). These findings indicate that the lower TEF in the obese subjects is uncorrected by weight loss, and thus it is a contributor to obesity rather than a consequence of obesity.

Regulation of glucose kinetics in trauma patients by insulin and glucagon

The current study was undertaken to evaluate the contribution of insulin and glucagon to regulation of glucose metabolism in man following severe, traumatic injury by manipulating concentrations of insulin and glucagon with infusions of somatostatin. Glucose kinetics were assessed with [U-14C, 6-(3)H]glucose in severely injured patients and compared with data obtained from patients recovering from minor, elective operative procedures. Glucose production was significantly increased in subjects with traumatic injury compared with control subjects (13.0 +/- 0.63 mumol/kg/min v 8.6 +/- 0.27 mumol/kg/min). There was no impairment in glucose oxidation by the injured patients. Modulation of insulin and glucagon with somatostatin indicated that non-insulin-mediated glucose uptake (NIMGU) was significantly elevated in injured patients (12.2 +/- 0.94 mumol/kg/min v 7.4 +/- 0.61 mumol/kg/min). Hepatic glucose output (HGO) in the absence of glucagon was also significantly elevated in injured patients (12.2 +/- 1.20 mumol/kg/min v 5.8 +/- 1.08 mumol/kg/min). Indirect calorimetry showed a 27% increase in resting energy expenditure (REE). Increased protein oxidation accounted for 56% of the increase in REE. Changes in carbohydrate and lipid oxidation accounted for 28% and 15% of the increase in REE. There was no correlation between the injury severity score of the injured patient and the degree of metabolic abnormality. It is concluded from these studies that (1) injured patients have a high rate of glucose turnover in the absence of glucagon and insulin; (2) the reliance on glucose as a source of energy is not diminished in injured subjects; and (3) increases in protein oxidation account for the majority of the increased REE found in injured patients.

The effect of plasma solutes on total-body-water measurements via NMR

Nuclear magnetic resonance (NMR) spectroscopy has been reported as an alternative method for quantitating deuterium oxide concentrations in the evaluation of total-body-water in humans. However, the presence of dissolved plasma proteins results in an underestimation of deuterium NMR (2H-NMR) intensity ratios, thereby causing an overestimation (5-6%) of total-body-water (TBW) values determined from nonsublimed patient plasma samples. We demonstrate that plasma samples must be corrected for the volume percentage of water in plasma. Correction of initial 2H-NMR intensity ratios with a factor of 0.93 results in intensity ratios comparable to those determined from plasma samples subjected to vacuum sublimation to remove all plasma solutes.

Whole-body protein kinetics in elective surgical patients receiving peptide or amino acid solutions

We compared the efficacy of two enteral solutions that were isonitrogenous and of identical amino acid composition but differed in that one solution contained only free amino acids whereas the other contained a mixture of free amino acids and peptides. Protein kinetics and nitrogen balance were evaluated in a group of six elective surgical patients. Primed-constant infusion with 15N-glycine was started 24h after gynecologic surgery and sustained over 3 days. During the first postoperative day, patients received enteral 0.45% saline. During postoperative days two and three, the patients received either the free amino acid solution or the mixture of peptides and free amino acids in a crossover design. There were no differences in protein kinetics or nitrogen balance with the two treatments.

Comparison of three methods for the estimation of total nitrogen losses in hospitalized patients

Since the measurement of total nitrogen output (TNO) is not routinely determined in the clinical setting, its level is frequently estimated using formulas based on the urinary urea nitrogen excretion (UUN). We measured TNO in 124 surgical patients over 990 days (TNO, 19.22 +/- 8.72 g N/day; total urinary nitrogen (TUN) 18.17 +/- 8.70 g N/day; UUN, 15.17 +/- 7.70 g N/day; mean gastrointestinal nitrogen (MGIN) 0.68 +/- 0.49 g N/day; integumental nitrogen (ITGN), 0.34 +/- 0.08 g N/day) and compared the results with the daily estimations using three different formulas: formula A, UUN + 4; formula B, UUN x 1.20 + 1.05, where 1.20 is the reciprocal of the mean ratio UUN/TUN and 1.05 the mean extraurinary nitrogen losses; and formula C, UUN x 1.0986 + 2.55, derived from the regression analysis of UUN vs TNO. TNO estimated by these formulas were 19.17 +/- 7.70, 19.26 +/- 9.24, and 19.22 +/- 8.70 g N/day, respectively. The regression analyses of the estimated TNO from the three formulas versus the measured TNO indicated that formulas A, B and C were equally accurate in estimating TNO over the entire range of UUN. However, when only values of UUN greater than or equal to 30 g N were considered, a modified formula A (UUN + 6) was the best predictor of TNO. Daily audits of the differences between the estimated and measured TNO showed comparable results for the three formulas. In 28.4 to 31.1% of the observed days the differences were higher than +/- 2 g N/day, an error which is not acceptable when estimating the protein requirements in many clinical conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

A physiologic basis for the provision of fuel mixtures in normal and stressed patients

It has been suggested that lipid is a preferred fuel in stressed patients. We evaluated glucose oxidation in 20 patients (sepsis, cancer of the colon, multiple trauma, controls) while they received TPN (5.65 mg glucose/kg/min). Respiratory quotient (RQ) was measured by indirect calorimetry and the percent VCO2 arising from the oxidation of glucose was measured using [U-14C] glucose. Since RQs were 1.0 or greater in all patients, the nonprotein energy utilized by them was calculated to be derived completely from glucose. However, the kinetic data showed that glucose contributed only 55-60% of the VCO2. Protein oxidation contributed less than 20% of the VCO2, as calculated from urinary nitrogen. The difference must have been derived from fatty acid oxidation. The glucose turnover that was not oxidized was presumed to be converted to lipid at an RQ of 8.6. The net oxygen consumption and carbon dioxide production from this overall distribution resulted in an RQ of about 1.0 with only 60% coming from glucose oxidation. Since all patients responded in the same manner, it appears that the proper ratio of glucose and lipid was dictated on a physiologic basis and not on the type of disease.

Glucose metabolism and colorectal carcinoma

We evaluated nine patients with colorectal cancer and six control patients in a postabsorptive state in an attempt to define the effect of cancer on glucose turnover, oxidation, recycling, and resting metabolic expenditures (RME). The glucose kinetics were determined using a double-labeled [U-14C] glucose and [6-3H] glucose, and energy expenditures were measured by indirect calorimetry. In addition, we also measured the same parameters in the cancer patient group on a total parenteral nutrition (TPN)-glucose system on the fourth day before and on the fifth day after removal of tumor. In the postabsorptive state, glucose turnover and oxidation rates were similar in the cancer and control group; however, the mean glucose pool size of the cancer group was 47% larger than the control group and was statistically significant (P = .05). Glucose recycling was also two times the control group and was statistically significant (P = .05). The recycling of glucose, both preoperatively and postoperatively, continued in the face of infused glucose; however, the rate was suppressed compared with the fasting cancer group. Postabsorptive RME of the cancer group did not differ from those predicted by the Harris-Benedict equation. Following a 4-day infusion of TPN-glucose that supplied a mean of two times the patients' energy needs, the preoperative cancer group showed a mean increase in RME of 25.6% and a 31.58% increase on the fifth postoperative day of TPN-glucose, presumably due to increased lipogenesis and to a much lesser extent from the increased protein synthesis (4 g positive N balance).(ABSTRACT TRUNCATED AT 250 WORDS)

Free amino acids in muscle: effect of muscle fiber population and denervation

One hindlimb of each rat was denervated by sectioning the sciatic nerve. Three days later, soleus, plantaris, and gastrocnemius muscles of the sham hindlimb and the contralateral denervated hindlimb were excised and analyzed for intracellular concentrations of 23 free amino acids and the dipeptides carnosine and anserine. Compared with the sham soleus (slow-twitch) muscle, the sham plantaris and gastrocnemius (fast-twitch) muscles showed 57-81% lower concentrations of histidine, glutamine, glutamate, aspartate, and serine and also 32-78% lower levels of taurine, citrulline, phosphoserine, and ornithine. On the other hand the fast-twitch muscles exhibited 31% higher concentrations of free glycine and alanine and 113-127% higher levels of carnosine and anserine than the soleus muscle. The denervation caused greater changes in soleus muscle than in the other two muscles. The denervation-induced changes in soleus muscle included 38-87% increases in concentrations of free valine, leucine, isoleucine, and glutamate associated with 21-56% decreases in the levels of glutamine, glycine, aspartate, serine, alanine, and citrulline. It is concluded that both muscle fiber population and muscle denervation have an independent effect on the intracellular concentrations of free amino acids in muscles.

Serum albumin. Differences in assay specificity

Serum albumin is one of the most common parameters used in evaluating nutritional status. Three of the popular methods available for measuring serum albumin are serum protein electrophoresis and the two dye binding methods: BCG and BCP. BCG is currently the most popular method because of its simplicity, rapidity, and cost. Although electrophoretic methods are considered more accurate, BCP has shown to correlate well with electrophoresis in most cases. BCG often overestimates serum albumin levels, although its specificity can be improved by minimizing contact time with the serum sample. The average difference between BCG methods and other methods is usually 0.5-0.6 g/dL. From a quantitative standpoint, some might consider the difference in specificity of BCG versus the other two methods to be insignificant; however, from a qualitative standpoint, the difference could easily alter the interpretation of nutritional assessment parameters. Because of differences in analytical methods, serum albumin measurements should be interpreted in the context of the assay being used and the accepted normal range for that laboratory. Likewise, published studies, especially those that stratify degrees of malnutrition and/or risk of complications based on specific serum albumin levels, should specify the assay methodology utilized.

Catabolic effect of dexamethasone in patients with major head injuries

In the records of our extensive metabolic studies on trauma victims, we found 16 head injured patients who had no other major injuries. Among them, nine had been given dexamethasone for at least 6 days. The other seven had not received any corticosteroids. There was no significant difference in the Glasgow Coma Scales of the treated and untreated groups. Metabolic balance studies were carried out for at least 3 days, including the periods when the treated patients were receiving dexamethasone. Mean nitrogen balance was -0.296 +/- 0.03 g/kg/day for the treated group and -0.182 +/- 0.03 g/kg/day for the untreated group. This difference was significant (p = 0.02, t-test). Our metabolic data are also consistent with those of other published studies, which used other corticosteroids and somewhat different methodologies. Thus, it is clearly established that corticosteroids cause significant degrees of catabolism in head injured patients, beyond what would "normally" be expected in such patients if they did not receive these drugs.

Validity of 3-methylhistidine excretion as an indicator of skeletal muscle protein breakdown in humans

The urinary excretion of 3-methylhistidine (3MEH) in humans and animals has been used as a biologic marker for skeletal muscle protein breakdown. In rats, it has been recently suggested that there is a significant contribution of 3MEH in urine from the gastrointestinal tract due to the rapid turnover of protein in that tissue. To evaluate this point in humans, six patients with short bowel were evaluated. They were placed on three-day meat-free diets while 24-hour urine collections were obtained. The mean +/- SEM 3MEH in the short-bowel group was 3.27 +/- 0.34 mumol/kg/d and the mean +/- SEM molar ratio of 3MEH to creatinine was 0.0212 +/- 0.0012. These data were not significantly different from the control group at 95% confidence level. The results suggest that the contribution of the small intestine appears to be negligible, therefore urinary 3MEH should continue to be a valid index of skeletal muscle breakdown in man.

Energy requirements for cancer patients and the effect of total parenteral nutrition

Limited data are available concerning resting metabolic expenditure (RME) in cancer patients and the effect of RME by varying glucose intake. This study describes the measurements on 21 patients with colorectal cancer while fasting and with incremental levels of standard TPN-glucose system by central vein. Following an overnight fast, the measured mean +/- SEM percent difference from the predicted RME for the male group was 4.13 +/- 1.67% and the female group, 2.09 +/- 2.09%. The overall mean percent difference of 2.95 +/- 1.45 suggests that colorectal cancer does not cause an increase in energy expenditure. Hepatic metastases in 11 of the patients did not influence RME. The data from the 21 patients indicate a statistically significant increase in RME with TPN compared to postabsorptive states in females of 37%, in males 21.88%, and combined of 29.88%. Progressively greater increases in RME were seen when calories provided incrementally exceeded the basal RME. Carbohydrate loading in excess of the patient's calorie need, as indicated by the respiratory quotient (RQ) greater than 1.0, results in fat synthesis and other energy-costing processes. The basal RME demonstrates that these cancer patients are not hypercatabolic, but do respond to high-level force-feeding with markedly increased metabolic expenditures.

The effect of major thermal injury on plasma ketone body levels

Eleven patients with more than 30% total body surface burns were studied during 3 days of starvation and three more days of unrestricted feeding following their injury. All patients developed marked protein mobilization as demonstrated by 3rd day urine nitrogen excretion of 17.1 g daily compared to control excretion of 11.8 g N daily. As a group, the patients failed to mount the expected ketonemic response during their initial period of starvation. Whereas normal fasted controls achieved plasma ketone body levels of 727 +/- 81 mumol/liter, the burn patients responded with an average level of 385 +/- 77 mumol/liter (p less than 0.01).

Monoacetoacetin and protein metabolism during parenteral nutrition in burned rats

The effect of intravenous infusion of monoacetoacetin (glycerol monoacetoacetate) as a non-protein energy source was evaluated in burned rats. During 3 days of parenteral nutrition, in which animals received 14 g of amino acids/kg body wt. per day exclusively (group I) or with the addition of isoenergetic amounts (523 kJ/kg per day) of dextrose (group II), a 1:1 mixture of dextrose and monoacetoacetin (group III) or monoacetoacetin (group IV), significant decreases in urinary nitrogen excretion and whole-body leucine oxidation were observed in the three groups given additional non-protein energy as compared with group I. Serum ketone bodies (acetoacetate and 3-hydroxybutyrate) were decreased in rats given dextrose, whereas glucose and insulin increased significantly. Monoacetoacetin-infused animals (group IV) had high concentrations of ketone bodies without changes in glucose and insulin, whereas animals infused with both monoacetoacetin and glucose (group III) showed intermediate values. On day 4 of nutritional support, whole-body L-leucine kinetics were measured by using a constant infusion of L-[1-14C]leucine. In comparison with group I, the addition of dextrose or monoacetoacetin produced a significant decrease in plasma leucine appearance and release from whole-body protein breakdown. Gastrocnemius-muscle protein-synthesis rates were also higher in the three groups receiving additional non-protein energy. These findings suggest that monoacetoacetin can effectively replace dextrose as an intravenous energy source in stressed rats. Both fuels are similar in decreasing weight loss, nitrogen excretion, leucine release from whole-body protein breakdown and oxidation, in spite of differences in energy substrate and insulin concentrations.

The effect of major thermal injury and carbohydrate-free intake on serum triglycerides, insulin, and 3-methylhistidine excretion

The severely burned patient responds differently to starvation ketosis in the early stage of injury as compared to the normal individual. A similar response has been observed in the patient after skeletal trauma and sepsis. In order to determine the extent of muscle protein contribution and the mechanism(s) involved, 11 burn patients with 35% to 80% BSA burn were resuscitated using carbohydrate-free solutions for 3 days followed by unrestricted intake. Blood was drawn daily and 24-hour urinary nitrogens were determined. Controls consisted of 10 preoperative elective surgical patients and two normal volunteers. The burned patients lost a mean +/- SEM of 17.1 +/- 1.72 g nitrogen per day on the third day. The mean +/- SEM ketone body response on the third day for burned patients was 385 +/- 77 mumol/l compared to 727 +/- 81 mumol/l for control patients. The mean +/- SEM 3-methylhistidine loss for burned patients on the third day was 9.83 +/- 0.82 mumol/kg compared to 3.6 mol/kg for control patients. Insulin levels on the third day of fast were three times the normal group. This insulin increase may be the modulating factor that suppresses excessive fat mobilization. This metabolic response causes a lower plasma ketone level, which may then necessitate the need for continued protein catabolism for glucose production for certain tissues. The protein contribution to the hypercatabolic response as assessed by increased urinary nitrogen losses is in part supported by an increased muscle protein breakdown as indicated by increased 3-methylhistidine excretion.

Evaluation of whole body nitrogen kinetics in acute metabolic acidosis

The data obtained after a pulse dose of L-[15N] alanine and [13C] urea in control and acidotic conscious dogs were analyzed to compute the whole body nitrogen turnover rates. Acute acidosis was induced and maintained by continuous HCl infusion. On the basis of a four pool model, the mean daily protein synthesis rate in the normal dog was calculated to be 10.8 g/kg compared to 7.6 g/kg in acidosis. Since all dogs were in negative nitrogen balance, the daily catabolic rate of protein was greater than the synthetic rate and the mean daily catabolic rate was 14.4 g protein/kg in normal dogs compared to 10.5 g protein/kg in acidotic dogs. The body urea pool size and excretion rates were decreased by 24 and 27%, respectively, due to acute acidosis, without any change in the fractional turnover rate. Thus the adaptive response to the induced acid challenge appears to be a reduction in the synthesis and breakdown rates of protein and also a decrease in the production and excretion rate of urea.

Net metabolic changes of zinc, copper, nitrogen, and potassium balances in skeletal trauma patients

Zinc, copper, nitrogen, and potassium balances of 10 male skeletal trauma patients were determined over 5-6 days each. Nutrition consisted of electrolyte/glucose and/or blood/blood product infusions. Patients were started on balance studies within 24 hr following injury. Zinc and copper were analyzed by atomic absorption while nitrogen was measured by the microKjeldahl technique and potassium by flame photometry. The mean daily balances for these patients were -1563 micrograms zinc, -266 micrograms copper, -20.0 g nitrogen and -29 mEq potassium for 5 patients receiving electrolyte/glucose infusions and +1273 micrograms zinc, +322 micrograms copper, -12.9 g nitrogen, and -26 mEq potassium for 5 patients receiving blood/blood products in addition to electrolyte/glucose. Routine daily maintenance supplementation of 2 mg zinc and 2 mg copper is recommended for skeletal trauma patients on electrolyte/glucose and those on electrolyte/glucose with blood/blood products intravenous infusions. Further balance studies are necessary to ascertain the level of zinc and copper supplementation needed by skeletal trauma patients receiving different nutritional support.

Clinical use of pulse rates to determine daily energy expenditures in trauma and surgical patients

This study was conducted to establish practical application by using pulse rates to determine resting energy expenditures in trauma and surgical patients. A continuous flow gas analyzer measured energy expenditures and a cardiotachometer/recorder determined pulse rates simultaneously. The study consisted of 18 normal subjects as controls, seven surgical patients (totaling 36 samples), a combination of the seven surgical and three trauma patients (totaling 23 samples). The group of seven surgical patients had a correlation coefficient of 0.531 when comparing pulse rate/min with kcal/m2/hr, and this was the best correlation among the group population studied. An attempt to establish a single regression line from individual patients showed no significant correlation, with the exception of two surgical patients. Of the total number of patient samples, we found no significant correlation between pulse rate and energy expenditures. Independently, Andrews (Am J Clin Nutr 24:1139-1147, 1971) and Payne (Am J Clin Nutr 24:1164-1170, 1971) suggested that there are multiple variables such as stroke volume, state of physical training, etc., that affect the outcome of such data. In this study, our variables were more extensive with respect to the severity of injuries and varying degrees of surgical procedures. The study concluded that there is no practical clinical use of pulse rates in determining daily resting energy expenditures of surgical or trauma patients.

Comparison between in vitro lymphocyte activity and metabolic changes in trauma patients

This study was designed to investigate the relationship of in vitro and in vivo components of host immunocompetence and various biochemical parameters of injury. Thirteen multiple trauma victims were evaluated within 2 to 3 days postinjury while maintained on 5% glucose. The mean nitrogen balance of the patients was -18 gm/24 hr and the resting metabolic expenditure was increased 22.3%. Seventy-five per cent of the patients skin tested were anergic or relatively anergic. Patient lymphocyte response to the T cell mitogens phytohemagglutinin and concanavalin A were suppressed 45 and 48%, respectively, when compared to 24 normal healthy individuals. Total lymphocyte count (1,558) and percentage of T lymphocytes (63%) were within normal limits. The suppression of lymphocyte response to mitogens correlated by regression analysis with the negative nitrogen balances and resting metabolic expenditures in these patients (p less than 0.05). The depression of lymphocyte activity can be correlated with the catabolic response of injury in multiple trauma patients.

Urinary excretion of 3-methylhistidine: an assessment of muscle protein catabolism in adult normal subjects and during malnutrition, sepsis, and skeletal trauma

The urinary excretion of 3-methylhistidine (3 MEH) has been shown to be a reliable index of muscle protein breakdown. It is decreased in protein-calorie malnutrition and increased during the hypercatabolic phase of sepsis and thermal trauma. Losses of 3 MEH after moderate to severe skeletal trauma in man and animals are reported as increased or unchanged. To clarify this response, 24 male and 6 female skeletal trauma patients were evaluated for 24 hr urinary losses of 3 MEH, nitrogen and creatinine. Eight of the 24 males also received a catabolic steroid for treatment of a head injury. In addition, 3 male and 1 female septic patients were similarly evaluated. Controls consisted of 10 volunteers on a meat free diet for 4 days and of 8 volunteers who were given only intravenous 5% dextrose in water for 3 days. The 3 MEH excretion for all control males was 3.6 mumole/Kg/day and for females was 2.8 Skeletal trauma produced a 280% increase for the males and a 225% increase for the females. Trauma with steroids caused a 325% increase. Sepsis induced a 227% increase in 3 MEH losses for males and 292% for females during the febrile episode. Creatinine excretion also increased significantly in response to trauma and sepsis but the magnitude of the increase was less than for 3 MEH. This was reflected in the 3 MEH to creatinine molar ratio increase from 0.018 for controls to 0.030-0.040 in sepsis and trauma. Patients with extensive body weight loss showed decreases in 3 MEH and creatinine excretion and a molar ratio similar to controls. The calculated contribution of muscle protein to whole body protein breakdown in the trauma and septic groups showed a twofold increase compared to the control group. The data indicate that the increased muscle protein catabolic response following stress of skeletal trauma and sepsis provides an insight on the origin of the large urinary nitrogen losses following such insults.

A comparison of the effects of skeletal trauma and surgery on the ketosis of starvation in man

The increase of plasma ketone bodies (acetoacetic acid and beta-hydroxybutyric acid) is related to the efficient protein-sparing adaptation during a total fast by healthy man. This study investigated the response to a total fast during the postinjury state. Twenty patients with skeletal or soft-tissue trauma received 3 days of carbohydrate-free intake and then 3 more days of carbohydrate intake. Control subjects were ten postoperative patients and two healthy volunteers who received similar nutritional treatment. The trauma patients lost nearly 20 gm of nitrogen/day, which was twice control, and had a resting energy expenditure of 27.07 kcal/kg, 21.4% greater than controls. Trauma was found related to an elevation in plasma glucose and to inhibit the rise in plasma ketone bodies and free fatty acids. In contrast, indirect calorimetry showed that fat contributed 63% of the nonprotein energy on the third day of fasting and injury. These data indicate that fat is utilized by the trauma patient but that fatty metabolism is abnormal compared to starvation in healthy or mildly stressed patients.