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1.
Dispensable Amino Acids, except Glutamine and Proline, Are Ideal Nitrogen Sources for Protein Synthesis in the Presence of Adequate Indispensable Amino Acids in Adult Men.
Cooper, L, Ball, RO, Pencharz, PB, Sakai, R, Elango, R
The Journal of nutrition. 2020;(9):2398-2404
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Abstract
BACKGROUND Nutritionally, there is a dietary requirement for indispensable amino acids (IAAs) but also a requirement for nitrogen (N) intake for the de novo synthesis of the dispensable amino acids (DAAs). It has been suggested that there might be a dietary requirement for specific DAAs. OBJECTIVES Experiment 1 tested whether 9 of the DAAs (Ala, Arg, Asn, Asp, Gln, Glu, Gly, Pro, Ser) are ideal N sources using the indicator amino acid oxidation (IAAO) technique. Experiment 2 examined whether there is a dietary requirement for Glu in adult men. METHODS Seven healthy men (aged 20-24 y) participated in 11 or 2 test diet intakes, in experiment 1 and 2, respectively, in a repeated measures design. In experiment 1, a base diet consisting of the IAA provided at the RDA was compared with test intakes with the base diet plus addition of individual DAAs to meet a 50:50 ratio of IAA:DAA on an N basis. In experiment 2, the diets corresponded to the amino acid pattern present in egg protein, in which all Glu and Gln was present as Glu, or removed, with Ser used to make the diets isonitrogenous. On each study day the IAAO protocol with l-[1-13C]phenylalanine was used to measure whole-body protein synthesis. RESULTS In experiment 1, repeated measures ANOVA with post hoc multiple comparisons showed that 7 of the 9 DAAs (Ala, Arg, Asn, Asp, Glu, Gly, Ser) decreased IAAO significantly (P < 0.05) compared with base IAA diet, the exceptions being Gln and Pro. In experiment 2, a paired t test did not find significant (P > 0.05) differences in the IAAO in response to removal and replacement of Glu intake. CONCLUSIONS The results suggest that in healthy men most DAAs are ideal N sources for protein synthesis, in the presence of adequate IAAs, and that endogenous synthesis of Glu is sufficient.Registered clinicaltrials.gov identifier: NCT02009917.
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Effect of Protein-Fortified Diet on Nitrogen Balance in Critically Ill Patients: Results from the OPINiB Trial.
Danielis, M, Lorenzoni, G, Azzolina, D, Iacobucci, A, Trombini, O, De Monte, A, Gregori, D, Beltrame, F
Nutrients. 2019;(5)
Abstract
Nitrogen balance (NB) is considered a good marker of adequate protein intake and it has been suggested to be a good predictor of patients' health outcomes. However, in literature, there is a lack of large randomized trials examining NB-guided protein intake in patients in intensive care units (ICUs). A randomized controlled trial enrolling patients admitted to ICU was done to compare changes in NB. Participants were randomized to a standard or protein-fortified diet (protein intake of 1.8 g/kg/day according to the guidelines of the Society of Critical Care Medicine and the American Society for Parenteral and Enteral Nutrition). The primary endpoint was represented by the NB on Day 1, 3, and study exit. Forty patients were enrolled in the study (19 in the protein-fortified group). The longitudinal analysis showed that, on Day 3, patients randomized to the protein-fortified diet were more likely (p < 0.001) to present better NB (at 3 days, patients in the protein-fortified diet were estimated to have a nitrate value of 5.22 g more than patients in the standard diet, 95% CI 3.86-6.58). The protein-fortified diet was found to be significantly and directly associated with changes in NB in critically ill patients admitted to ICU.
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Pilot Study Examining the Influence of Potassium Bicarbonate Supplementation on Nitrogen Balance and Whole-Body Ammonia and Urea Turnover Following Short-Term Energy Restriction in Older Men.
Margolis, LM, Ceglia, L, Rivas, DA, Dawson-Hughes, B, Fielding, RA
Nutrients. 2018;(5)
Abstract
With aging there is a chronic low-grade metabolic-acidosis that may exacerbate negative protein balance during weight loss. The objective of this randomized pilot study was to assess the impact of 90 mmol∙day-1 potassium bicarbonate (KHCO₃) versus a placebo (PLA) on 24-h urinary net acid excretion (NAE), nitrogen balance (NBAL), and whole-body ammonia and urea turnover following short-term diet-induced weight loss. Sixteen (KHCO₃; n = 8, PLA; n = 8) older (64 ± 4 years) overweight (BMI: 28.5 ± 2.1 kg∙day-1) men completed a 35-day controlled feeding study, with a 7-day weight-maintenance phase followed by a 28-day 30% energy-restriction phase. KHCO₃ or PLA supplementation began during energy restriction. NAE, NBAL, and whole-body ammonia and urea turnover (15N-glycine) were measured at the end of the weight-maintenance and energy-restriction phases. Following energy restriction, NAE was -9.8 ± 27.8 mmol∙day-1 in KHCO₃ and 43.9 ± 27.8 mmol∙day-1 in PLA (p < 0.05). No significant group or time differences were observed in NBAL or ammonia and urea turnover. Ammonia synthesis and breakdown tended (p = 0.09) to be higher in KHCO₃ vs. PLA following energy restriction, and NAE was inversely associated (r = -0.522; p < 0.05) with urea synthesis in all subjects. This pilot study suggests some benefit may exist with KHCO₃ supplementation following energy restriction as lower NAE indicated higher urea synthesis.
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Processing Adipose-Rich Mohs Samples: A Comparative Study of Effectiveness of Pretreatment With Liquid Nitrogen Versus Flash Freezing Spray.
Reserva, J, Kozel, Z, Krol, C, Speiser, J, Adams, W, Tung, R
The American Journal of dermatopathology. 2017;(11):838-841
Abstract
Processing of adipose-rich Mohs micrographic surgery (MMS) specimens poses challenges that may preclude complete margin evaluation. In this setting, the value of additional freezing methods using various cooling agents has not been previously investigated. The aim of this study is to compare the frozen section quality of high-adipose Mohs specimens processed without additional cooling treatments versus those pretreated with 1,1,1,2-tetrafluoroethane (TFE) or liquid nitrogen (LN2). A set of 3 sections were each taken from 24 adipose-rich Mohs micrographic surgery specimens. A section from each set was subjected to either no additional cooling treatment (control), two 10-second pulse sprays of 1,1,1,2-tetrafluoroethane, or three 2-second pulse sprays of LN2. After staining, 2 blinded raters evaluated slide quality based on the presence or absence of the following features: margin completeness, nuclear clearing, epidermal or adipose folding, holes, or venetian blind-like artifacts. Pretreatment of the sample with LN2 produced a significantly (P < 0.001) greater number of high-quality slides (19/24) compared to pretreatment with 1,1,1,2-tetrafluoroethane (1/24) and no additional treatment (0/24). The adjunctive use of LN2 spray before tissue embedding circumvents the challenges of processing "thick" (high-adipose) specimens and facilitates the production of high-quality frozen section slides during Mohs micrographic surgery.
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Effect of urine urea nitrogen and protein intake adjusted by using the estimated urine creatinine excretion rate on the antiproteinuric effect of angiotensin II type I receptor blockers.
Chin, HJ, Kim, DK, Park, JH, Shin, SJ, Lee, SH, Choi, BS, Kim, S, Lim, CS
Nutrition (Burbank, Los Angeles County, Calif.). 2015;(11-12):1333-8
Abstract
OBJECTIVES The aim of this study was to determine the role of protein intake on proteinuria in chronic kidney disease (CKD), as it is presently not conclusive. METHODS This is a subanalysis of data from an open-label, case-controlled, randomized clinical trial on education about low-salt diets (NCT01552954). We estimated the urine excretion rate of parameters in a day, adjusted by using the equation for estimating urine creatinine excretion, and analyzed the effect of urine urea nitrogen (UUN), as well as estimating protein intake on the level of albuminuria in hypertensive patients with chronic kidney disease. RESULTS Among 174 participants from whom complete 24-h urine specimens were collected, the estimates from the Tanaka equation resulted in the highest accuracy for the urinary excretion rate of creatinine, sodium, albumin, and UUN. Among 227 participants, the baseline value of estimated urine albumin excretion (eUalb) was positively correlated with the estimated UUN (eUUN) or protein intake according to eUUN (P = 0.012 and P = 0.038, respectively). We were able to calculate the ratios of eUalb and eUUN in 221 participants and grouped them according to the ratio of eUUN during 16-wk trial period. The proportion of patients that achieved a decrement of eUalb ≥25% during 16 wk with an angiotensin II type I receptor blocker (ARB) medication was 80% (24 of 30) in group 1, with eUUN ratio ≤-25%; 82.2% (111 of 135) in group 2, with eUUN ratio between -25% and 25%; and 66.1% (37 and 56) in group 3, with eUUN ratio ≥25% (P = 0.048). The probability of a decrease in albuminuria with ARB treatment was lower in patients with an increase of eUUN or protein intake during the 16 wk of ARB treatment, as observed in multiple logistic regression analysis as well. CONCLUSIONS The estimated urine urea excretion rate showed a positive association with the level of albuminuria in hypertensive patients with chronic kidney disease. The increase of eUUN excretion ameliorated the antiproteinuric effect of ARB.
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The effect of low-nitrogen and low-calorie parenteral nutrition combined with enteral nutrition on inflammatory cytokines and immune functions in patients with gastric cancer: a double blind placebo trial.
Li, JH, Han, L, Du, TP, Guo, MJ
European review for medical and pharmacological sciences. 2015;(8):1345-50
Abstract
OBJECTIVE The aim of this study is to investigate the effect of low-nitrogen and low-calorie parenteral nutrition (PN) combined with enteral nutrition (EN) on the inflammatory cytokines and immune function in patients with gastric cancer. PATIENTS AND METHODS Between May 2012 and May 2014, 90 patients undergoing surgery for gastric cancer in our institution were involved in this double blind placebo study and randomly divided into experimental group and control group, 45 patients of each group. Patients in the control group would receive total parenteral nutrition (TPN) whereas patients in the experimental group would be supported with low-nitrogen and low-calorie PN combined with EN. RESULTS On the 7th postoperative day 7, levels of IgA, IgM and IgG in experimental group were significantly higher than those in the control group and preoperative values (p < 0.05). CRP level was significantly lower than that of controls and preoperatively (p < 0.05). Levels of IL-2 and TNF-α were significantly higher than those of controls and preoperatively (p < 0.05). CONCLUSIONS As low-nitrogen and low-calorie PN combined with EN can effectively improve the immune function, reduce the inflammatory reactions and improve the postoperative quality of life (QoL) and prognosis in patients with gastric cancer, it is suitable for clinical application.
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Dietary protein-induced increases in urinary calcium are accompanied by similar increases in urinary nitrogen and urinary urea: a controlled clinical trial.
Bihuniak, JD, Simpson, CA, Sullivan, RR, Caseria, DM, Kerstetter, JE, Insogna, KL
Journal of the Academy of Nutrition and Dietetics. 2013;(3):447-451
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Abstract
To determine the usefulness of urinary urea as an index of dietary protein intake, 10 postmenopausal women were enrolled in and completed a randomized, double-blind, cross-over feeding trial from September 2008 to May 2010 that compared 10 days of a 45-g whey supplement with 10 days of a 45-g maltodextrin control. Urinary nitrogen, urinary calcium, urinary urea, and bone turnover markers were measured at days 0, 7, and 10. Paired sample t tests, Pearson's correlation statistic, and simple linear regression were used to assess differences between treatments and associations among urinary metabolites. Urinary nitrogen/urinary creatinine rose from 12.3±1.7 g/g (99.6±13.8 mmol/mmol) to 16.8±2.2 g/g (135.5±17.8 mmol/mmol) with whey supplementation, but did not change with maltodextrin. Whey supplementation caused urinary calcium to rise by 4.76±1.84 mg (1.19±0.46 mmol) without a change in bone turnover markers. Because our goal was to estimate protein intake from urinary nitrogen/urinary creatinine, we used our data to develop the following equation: protein intake (g/day)=71.221+1.719×(urinary nitrogen, g)/creatinine, g) (R=0.46, R(2)=0.21). As a more rapid and less costly alternative to urinary nitrogen/urinary creatinine, we next determined whether urinary urea could predict protein intake and found that protein intake (g/day)=63.844+1.11×(urinary urea, g/creatinine, g) (R=0.58, R(2)=0.34). These data indicate that urinary urea/urinary creatinine is at least as good a marker of dietary protein intake as urinary nitrogen and is easier to quantitate in nutrition intervention trials.
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The metabolic effect of resistant starch and yoghurt on the renal and faecal nitrogen and ammonia excretion in humans as measured by lactose-[(15)N2]ureide.
Wutzke, KD, Scholübbers, D
Isotopes in environmental and health studies. 2013;(4):464-70
Abstract
Resistant starch (RS) and Lactobacillus acidophilus yoghurt (LC1) were supplemented simultaneously in healthy adults to evaluate the effect on the urinary and faecal nitrogen and ammonia excretion by means of lactose-[(15)N2]ureide ((15)N-LU) degradation. Nineteen subjects received a regular daily diet either without or with supplementation of an RS-LC1-mixture composed of fibre of potatoes (RS type 1), wrinkle pea starch (RS type 2), and LC1 over a 20-day period in randomised order. Thereafter, (15)N-LU was administered together with breakfast. Urine and faeces were collected over a period of 48 and 72 h, respectively. The (15)N abundances were measured by isotope ratio mass spectrometry. The intake of the pre- and probiotic mixture composed of RS of type 1, type 2 and of LC1 significantly lowered the colonic generation and the renal excretion of toxic (15)NH3 and functioned as an ammonia shift from urinary to faecal (15)N excretion when using (15)N-LU as a xenobiotic marker.
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A protein-leucine supplement increases branched-chain amino acid and nitrogen turnover but not performance.
Nelson, AR, Phillips, SM, Stellingwerff, T, Rezzi, S, Bruce, SJ, Breton, I, Thorimbert, A, Guy, PA, Clarke, J, Broadbent, S, et al
Medicine and science in sports and exercise. 2012;(1):57-68
Abstract
PURPOSE This study aimed to determine the effect of postexercise protein-leucine coingestion with CHO-lipid on subsequent high-intensity endurance performance and to investigate candidate mechanisms using stable isotope methods and metabolomics. METHODS In this double-blind, randomized, crossover study, 12 male cyclists ingested a leucine/protein/CHO/fat supplement (LEUPRO 7.5/20/89/22 g · h(-1), respectively) or isocaloric CHO/fat control (119/22 g · h(-1)) 1-3 h after exercise during a 6-d training block (intense intervals, recovery, repeated-sprint performance rides). Daily protein intake was clamped at 1.9 g · kg(-1) · d(-1) (LEUPRO) and 1.5 g · kg(-1) · d(-1) (control). Stable isotope infusions (1-(13)C-leucine and 6,6-(2)H2-glucose), mass spectrometry-based metabolomics, and nitrogen balance methods were used to determine the effects of LEUPRO on whole-body branched-chain amino acid (BCAA) and glucose metabolism and protein turnover. RESULTS After exercise, LEUPRO increased BCAA levels in plasma (2.6-fold; 90% confidence limits = ×/÷ 1.1) and urine (2.8-fold; ×/÷ 1.2) and increased products of BCAA metabolism plasma acylcarnitine C5 (3.0-fold; ×/÷ 0.9) and urinary leucine (3.6-fold; ×/÷ 1.3) and β-aminoisobutyrate (3.4-fold; ×/÷ 1.4), indicating that ingesting ~10 g leucine per hour during recovery exceeds the capacity to metabolize BCAA. Furthermore, LEUPRO increased leucine oxidation (5.6-fold; ×/÷ 1.1) and nonoxidative disposal (4.8-fold; ×/÷ 1.1) and left leucine balance positive relative to control. With the exception of day 1 (LEUPRO = 17 ± 20 mg N · kg(-1), control = -90 ± 44 mg N · kg(-1)), subsequent (days 2-5) nitrogen balance was positive for both conditions (LEUPRO = 130 ± 110 mg N · kg(-1), control = 111 ± 86 mg N · kg(-1)). Compared with control feeding, LEUPRO lowered the serum creatine kinase concentration by 21%-25% (90% confidence limits = ± 14%), but the effect on sprint power was trivial (day 4 = 0.4% ± 1.0%, day 6 = -0.3% ± 1.0%). CONCLUSIONS Postexercise protein-leucine supplementation saturates BCAA metabolism and attenuates tissue damage, but effects on subsequent intense endurance performance may be inconsequential under conditions of positive daily nitrogen balance.
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Evaluation of the effects of a preoperative 2-hour fast with maltodextrine and glutamine on insulin resistance, acute-phase response, nitrogen balance, and serum glutathione after laparoscopic cholecystectomy: a controlled randomized trial.
Dock-Nascimento, DB, de Aguilar-Nascimento, JE, Magalhaes Faria, MS, Caporossi, C, Slhessarenko, N, Waitzberg, DL
JPEN. Journal of parenteral and enteral nutrition. 2012;(1):43-52
Abstract
BACKGROUND Prolonged preoperative fasting increases insulin resistance (IR). The authors investigated whether an abbreviated preoperative fast with glutamine (GLN) plus a carbohydrate (CHO)-based beverage would improve the organic response after surgery. METHODS Forty-eight female patients (19-62 years) were randomized to either standard fasting (control group) or to fasting with 1 of 3 different beverages before video-cholecystectomy. Beverages were consumed 8 hours (400 mL; placebo group: water; GLN group: water with 50 g maltodextrine plus 40 g GLN; and CHO group: water with 50 g maltodextrine) and 2 hours (200 mL; placebo: water; GLN: water with 25 g maltodextrine plus 10 g GLN; and CHO: water with 25 g maltodextrine) before anesthesia. Blood samples were collected pre- and postoperatively. RESULTS The mean (SEM) postoperative homeostasis model assessment-insulin resistance was greater (P < .05) in control patients (4.3 [1.3]) than in the other groups (placebo, 1.6 [0.3]; CHO, 2.3 [0.4]; and GLN, 1.5 [0.1]). Glutathione was significantly higher (P < .01) in the GLN group than in both CHO and control groups. Interleukin-6 increased in all groups except the GLN group. The C-reactive protein/albumin ratio was higher (P < .05) in controls than in CHO and GLN groups. The nitrogen balance was less negative in GLN (-2.5 [0.8] gN) than in both placebo (-9.0 [2] gN; P = .001) and control (-6.6 [0.4] gN; P = .04) groups. CONCLUSIONS Preoperative intake of a GLN-enriched CHO beverage appears to improve IR and antioxidant defenses and decreases the inflammatory response after video-cholecystectomy.