De novo lipogenesis predicts short-term body-composition response by bioelectrical impedance analysis to oral nutritional supplements in HIV-associated wasting.

We studied the effects of enteral supplements on protein and energy intakes, body composition, energy expenditure, and gastrointestinal histology in 49 subjects with human immunodeficiency virus-associated weight loss (12.7 +/- 0.9% of body wt). We also determined whether a stable-isotope mass spectrometric measurement at baseline might predict the short-term response of fat-free mass (FFM) measured by bioelectrical impedance analysis. Thirty-nine subjects completed the study after being randomly assigned to receive either a whole-protein-based (n = 22) or a peptide-based (n = 17) formula. A nonsupplemented, nonrandomly assigned group (n = 13) was followed concurrently. Both formulas were well tolerated. Voluntary intakes of energy and protein from nonsupplement sources decreased significantly during supplementation [by 819-1638 kJ (196-382 kcal)/d and 5.6-14.4 g protein/d, respectively; P < 0.01] but to a lesser extent than the intake from the supplement [2300-2510 kJ(550-600 kcal)/d and 19-28 g protein/d, respectively], so that net increases in intakes of protein and energy (P < 0.03), as well as of several vitamins and trace elements were increased. Nevertheless, the mean FFM did not increase for the group as a whole, although there was considerable interindividual heterogeneity. Changes in FFM at 6 wk were significantly inversely correlated (r = 0.65, P < 0.01) with baseline synthesis of fat (de novo hepatic lipogenesis), but not with other potential measures of energy intake (insulin-like growth factor 1 or its binding protein) or inflammation (soluble tumor necrosis factor receptors I or II). The prospective identification of FFM response by measurement of de novo hepatic lipogenesis supported the hypothesis that the subset of wasting patients whose FFM is unresponsive to nutrient supplementation have altered nutrient metabolism.

Weight loss, the gut and the inflammatory response in aids patients.

UNLABELLED: The objective of this study was to test the hypothesis that the integrity of the large bowel wall in AIDS patients is compromised in a manner that favours the chronic translocation of bacteria and/or products of bacterial metabolism into the bloodstream. When such translocation occurs, it induces a characteristic stress/inflammatory response in the body. Urinary butyrate, a unique product of colonic microbial metabolism, was used to assess gut wall permeability. Excretion of the pro-inflammatory cytokine IL-6 in the urine was used as a marker for the stress/inflammatory response. Four groups of subjects were studied, controls (n = 12), HIV + (n = 35) and AIDS patients with (n = 14) and without (n = 17) weight loss. RESULTS: measurable amounts of interleukin 6 (IL-6) and butyrate were found in the urine of all subjects. There were no significant differences in IL-6 excretion between the controls (0.68 +/- 0.64 pg/ml), asymptomatic HIV + subjects (0.59 +/- 0.37 pg/ml) and AIDS patients without weight loss (1.18 +/- 0.33 pg/ml) but IL-6 levels were significantly higher in the AIDS group with weight loss (4.02 +/- 1.26 pg/ml, P < 0.05). A similar pattern of results was found with interleukin 1 receptor antagonist (IL-1ra). Like IL-6 and (IL-1ra), urinary butyrate levels were increased in the AIDS patients with weight loss (2.83 +/- 0.67 mumol/l) relative to the controls (1.31 +/- 0.13 mumol/l, P < 0.05), with the HIV + patients (1.65 +/- 0.18 mumol/l) and AIDS patients without weight loss (1.90 +/- 0.22 mumol/l) falling in between. The data are consistent with a low, but chronic rate of bacteria and/or bacterial products seeping across a compromised colonic wall causing a chronic low stress response in AIDS patients.

Cigarette smoking, intracellular vitamin deficiency, and occurrence of micronuclei in epithelial cells of the buccal mucosa.

The study focuses on the assessment of chromosomal damage associated with folate and vitamin B12 deficiency, and with cigarette smoking in a tissue directly exposed to cigarette smoke (buccal mucosa) while controlling for potential confounding factors. A cross-sectional study was carried out among 39 current smokers (CSs) and 60 noncurrent smokers (NCSs). Buccal mucosal cells, saliva, and blood samples were collected from each subject. The Health Habits and History Questionnaire (Block et al., 1986) was modified to obtain dietary and other relevant information. Methods used to measure folate, vitamin B12 levels, and the frequency of micronucleated cells in buccal mucosal cells gave reproducible results. The study results suggest that CSs have buccal mucosal folate and vitamin B12 levels that are lower than those among NCSs. CSs were three times more likely to have micronucleated buccal mucosal cells compared to NCSs. There appeared to be no association between low buccal folate and vitamin B12 levels chromosomal damage. The salivary vitamin B12 concentrations and plasma vitamin C and E concentrations, however, seem to be marginally protective against the occurrence of buccal mucosal micronuclei, whereas plasma beta-carotene seems to increase the occurrence of micronuclei. Overall, the results do not support the concept that localized folate and vitamin B12 deficiencies in the buccal mucosal cells of smokers are associated with chromosomal damage in those cells. The presence of vitamin B12 deficiencies in the buccal mucosal cells of smokers are associated with chromosomal damage in those cells. The presence of vitamin B12 in the immediate environment (saliva) and vitamin C and E in the plasma, however, appear to be marginally protective against chromosomal damage in buccal mucosal cells.

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)

Local and systemic effects of cigarette smoking on folate and vitamin B-12.

A cross-sectional study was carried out among 39 current smokers (CS) and 60 noncurrent smokers (NCS) to evaluate the effects of cigarette smoking on folate and vitamin B-12 concentrations in the circulation and in tissues directly exposed to cigarette smoke. Univariate analysis showed significantly lower plasma, red blood cell (RBC), and buccal mucosa (BM) folate and BM vitamin B-12 concentrations in CS compared with NCS. The association between smoking and folate and vitamin B-12 concentrations in plasma, RBCs, and BM cells was reduced after other variables were controlled for. Total folate intake and plasma vitamin C concentrations were significant predictors of plasma and RBC folate concentrations. The plasma and RBC concentrations of folate were significantly lower in subjects who had last smoked < 1 h before the blood sample was drawn than in subjects who had smoked earlier. At the current recommended dietary allowance (RDA) for folate, CS had 42% lower plasma folate concentrations than NCS, whereas at an intake three times the RDA, the plasma folate concentration was the same for CS and NCS. The results also suggested that CS have BM folate and vitamin B-12 concentrations that are lower than those of NCS.

Long-term effects of early nutritional support with new enterotropic peptide-based formula vs. standard enteral formula in HIV-infected patients: randomized prospective trial.

Despite association with adverse clinical outcome, human immunodeficiency virus (HIV)-associated malnutrition has been relatively refractory to conventional nutrition management. Consequently, a prospective randomized trial was conducted to evaluate a new peptide-based enteral formula (NEF) in contrast to a standard enteral formula (SEF) in patients with HIV infection. Eighty early-stage largely asymptomatic patients were randomized into a dietary regimen supplemented with either a ready-to-feed NEF (18.7% protein, 65.5% carbohydrate, 15.8% fat; 1.28 kcal/ml) or SEF (14% protein, 55% carbohydrate, 31% fat; 1.06 kcal/ml). Patients received 2-3 8-oz cans of the NEF or SEF supplement per day for 6 mo. Parameters evaluated at 0 (baseline), 3, and 6 mo included adherence, weight change, anthropometric measurements, serum biochemical indices, gastrointestinal symptoms, physical performance, and intercurrent health events (including hospitalizations). For the 56 evaluable patients, those supplemented with NEF maintained their body weight significantly (p = 0.04) better, had significantly (p = 0.03) more stable triceps skin-fold measurements, and had significantly (p = 0.04) lower blood urea nitrogen than patients consuming the SEF supplement. Consumption of the NEF supplement was also associated with significantly reduced hospitalizations during the 3- to 6-mo evaluation period (p = 0.02). The NEF supplement was well tolerated and did not result in untoward clinical effects. These data suggest that supplemental use of an NEF provides superior nutritional management compared with an SEF for patients with early-stage HIV infection.

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)

Effect of smoking on folate levels in buccal mucosal cells.

The objective of the study was to document the existence of localized deficiency of folate in a tissue exposed to cigarette smoke, by analysis of oral and circulatory levels of this vitamin in smokers and non-smokers. Buccal mucosal cells and blood samples were collected from 25 smokers and 34 non-smokers. The Health Habits and History Questionnaire was completed by each subject. A 96-well plate L. casei assay, along with preincubation with a folate-free chick pancreas pteroyl-gamma-glutamyl hydrolase, was used to quantitate total buccal mucosal cell folates. The reproducibility (CV 5 to 7%) and recovery (95 to 106%) of the folate assay were satisfactory. Smokers had significantly lower buccal mucosal cell folate levels than did non-smokers. The mean plasma folate level of smokers although within normal limits, was also significantly lower than that of non-smokers. There were no significant differences in mean dietary folate intake or in alcohol consumption between the 2 groups. The strength of the positive association between smoking and plasma and buccal mucosal cell folate deficiency (by any definition) was moderate to strong and statistically significant. Our results indicate that cigarette smoking may result in a localized folate deficiency in buccal mucosal cells, independent of the plasma folate levels.

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.

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.

The effect of palmitoyl-CoA binding to albumin on the apparent kinetic behavior of carnitine palmitoyltransferase I.

Substrate saturation plots of carnitine palmitoyltransferase I activity from isolated rat liver mitochondria vs. palmitoyl-CoA concentration in the presence of bovine serum albumin have been reported to yield sigmoidal kinetics. Under identical assay conditions we have confirmed these observations as reflected by nonlinear Lineweaver-Burke plots (1/vi vs. 1/[S]) an average Hill coefficient of napp. = 1.98 +/- 0.09 (Mean +/- S.E. from four separate experiments). For these determinations the enzyme activity was plotted against the total [palmitoyl-CoA] in the presence of 0.13% bovine serum albumin. Utilizing the total [palmitoyl-CoA] to determine the kinetic properties of carnitine palmitoyltransferase I would be valid only if the relationship between total and free [palmitoyl-CoA] was linear, which is not the case as we have previously shown. When carnitine palmitoyltransferase I substrate saturation kinetics were reanalyzed using the previously determined free [palmitoyl-CoA]'s, the plots revealed a shift to standard hyperbolic kinetics. This observation was confirmed by an average Hill coefficient of napp. = 1.04 +/- 0.10 (Mean +/- S.E.) and linear Lineweaver-Burke plots. The double-reciprocal plots from these analyses yielded an average S0.5 of 2.55 +/- 0.82 microM (Mean +/- S.E.) palmitoyl-CoA and Vmax of 19.69 +/- 5.48 nmol/min per mg protein. These studies clearly demonstrate the importance of defining the free [palmitoyl-CoA] when analyzing the kinetics of carnitine palmitoyltransferase I in the presence of bovine serum albumin.

The binding of palmitoyl-CoA to bovine serum albumin.

Bovine serum albumin (BSA) is routinely utilized in vitro to prevent the adverse detergent effects of long-chain acyl-CoA esters (i.e., palmitoyl-CoA) in enzyme assays. Determination of substrate saturation kinetics in the presence of albumin would only be valid if the relationship between bound and free substrate concentrations was known. To elucidate the relationship between bound and free palmitoyl-CoA concentrations in the presence of BSA, several different techniques including equilibrium dialysis, equilibrium partitioning, fluorescence polarization and direct fluorescence enhancement were investigated. Direct fluorescence enhancement using a custom synthesized fluorescent probe, 16-(9-anthroyloxy)palmitoyl-CoA (AP-CoA), was the best approach to this question. Measurement of the relationship between mol of palmitoyl-CoA bound per mol of BSA (nu) versus -log[free palmitoyl-CoA] revealed that the binding of palmitoyl-CoA to BSA, like palmitate was nonlinear, suggesting the presence of more than one class of acyl-CoA binding sites. Computer analyses of the binding data gave a best fit to the 2,4 two-class Scatchard model, suggesting the presence of two high-affinity primary binding sites (k1 = (1.55 +/- 0.46) x 10(-6) M-1) and four lower affinity secondary binding sites (k2 = (1.90 +/- 0.09) x 10(-8) M-1). Further analyses using the six parameter stoichiometric (stepwise) ligand binding model supports the existence of six binding sites with the higher affinities associated with the binding of the first mole of palmitoyl-CoA and weaker binding occurring after the first two sites are occupied. The association constants from this model of multiple binding diminish sequentially (i.e., K1 greater than K2 greater than K3 greater than...greater than or equal to K6), suggesting that each mol of long-chain acyl-CoA binds to BSA with decreasing affinities.