Electrocatalytic Synthesis of Essential Amino Acids from Nitric Oxide Using Atomically Dispersed Fe on N-doped Carbon.

How to transfer industrial exhaust gases of nitrogen oxides into high-values product is significantly important and challenging. Herein, we demonstrate an innovative method for artificial synthesis of essential α-amino acids from nitric oxide (NO) by reacting with α-keto acids through electrocatalytic process with atomically dispersed Fe supported on N-doped carbon matrix (AD-Fe/NC) as the catalyst. A yield of valine with 32.1 µmol mgcat -1 is delivered at -0.6 V vs. reversible hydrogen electrode, corresponding a selectivity of 11.3 %. In situ X-ray absorption fine structure and synchrotron radiation infrared spectroscopy analyses show that NO as nitrogen source converted to hydroxylamine that promptly nucleophilic attacked on the electrophilic carbon center of α-keto acid to form oxime and subsequent reductive hydrogenation occurred on the way to amino acid. Over 6 kinds of α-amino acids have been successfully synthesized and gaseous nitrogen source can be also replaced by liquid nitrogen source (NO3 - ). Our findings not only provide a creative method for converting nitrogen oxides into high-valued products, which is of epoch-making significance towards artificial synthesis of amino acids, but also benefit in deploying near-zero-emission technologies for global environmental and economic development.

Dietary supplementation of branched-chain amino acids increases muscle net amino acid fluxes through elevating their substrate availability and intramuscular catabolism in young pigs.

Branched-chain amino acids (BCAA) have been clearly demonstrated to have anabolic effects on muscle protein synthesis. However, little is known about their roles in the regulation of net AA fluxes across skeletal muscle in vivo. This study was aimed to investigate the effect and related mechanisms of dietary supplementation of BCAA on muscle net amino acid (AA) fluxes using the hindlimb flux model. In all fourteen 4-week-old barrows were fed reduced-protein diets with or without supplemental BCAA for 28 d. Pigs were implanted with carotid arterial, femoral arterial and venous catheters, and fed once hourly with intraarterial infusion of p-amino hippurate. Arterial and venous plasma and muscle samples were obtained for the measurement of AA, branched-chain α-keto acids (BCKA) and 3-methylhistidine (3-MH). Metabolomes of venous plasma were determined by HPLC-quadrupole time-of-flight-MS. BCAA-supplemented group showed elevated muscle net fluxes of total essential AA, non-essential AA and AA. As for individual AA, muscle net fluxes of each BCAA and their metabolites (alanine, glutamate and glutamine), along with those of histidine, methionine and several functional non-essential AA (glycine, proline and serine), were increased by BCAA supplementation. The elevated muscle net AA fluxes were associated with the increase in arterial and intramuscular concentrations of BCAA and venous metabolites including BCKA and free fatty acids, and were also related to the decrease in the intramuscular concentration of 3-MH. Correlation analysis indicated that muscle net AA fluxes are highly and positively correlated with arterial BCAA concentrations and muscle net BCKA production. In conclusion, supplementing BCAA to reduced-protein diet increases the arterial concentrations and intramuscular catabolism of BCAA, both of which would contribute to an increase of muscle net AA fluxes in young pigs.

Determination of ß-hydroxy-ß-methylbutyrate concentration and enrichment in human plasma using chemical ionization gas chromatography tandem mass spectrometry.

Our objective was to develop a quick and simplified method for the determination of ß-Hydroxy-ß-methylbutyrate (HMB) and ɑ-ketoisocaproic acid (KIC) concentrations and enrichments by GC/MS/MS to determine the turnover rate of HMB in humans. In experiment 1, we provided a pulse of L-[5,5,5-2H3]leucine to younger adults in the postabsorptive state then collected blood samples over a 4h time period. In experiment 2, we provided a pulse of [3,4,methyl-13C3]HMB to older adults in the postabsorptive state then collected blood samples over a 3h time period. Plasma concentrations of KIC and HMB and MPE of KIC and HMB were determined by GC/MS/MS. Plasma enrichment of leucine was determined by LC/MS/MS. To determine plasma enrichment of [5,5,5-2H3]HMB and [3,4,methyl-13C3]HMB, samples were derivatized using pentafluorobenzyl bromide and analyzed using chemical ionization mode. The final methods used included multiple reaction monitoring of transitions 117.3>59.3 for M+0 and 120.3>59.3 for M+3. In experiment 1, peak MPE of Leu peaked at 9.76% generating a peak MPE of KIC at 2.67% and a peak HMB MPE of 0.3%. In experiment 2, the rate of appearance for HMB was 0.66µmol/kg ffm/h. We calculated that production of HMB in humans accounts for 0.66% of total leucine turnover.

Ketosteril® (aminoácidos essenciais + ceto-análogos) para pacientes com doença renal crônica em restrição proteica / Ketosteril® (essential amino acids + keto-analogues) for patients with chronic kidney disease in protein restriction

CONTEXTO: A Doença Renal Crônica (DRC) é caracterizada pela presença de alterações estruturais ou da função dos rins, por um período igual ou maior que três meses. Essa definição classifica como portadores de DRC aqueles pacientes que possuem alguma lesão renal evidenciada por anormalidades histopatológicas ou de marcadores de lesão renal, incluindo alterações sanguíneas, urinárias ou dos exames de imagem, independente da taxa de filtração glomerular (TFG). Além disso, pacientes que apresentam uma TFG < 60 mL/min/1,73 m2 com ou sem lesão renal, por um período igual ou superior a três meses, também são considerados como portadores de DRC. TECNOLOGIA: Ketosteril® (aminoácidos essenciais + ceto-análogos). PERGUNTA: Eficácia do Ketosteril® para pacientes com doença renal crônica em restrição proteica. EVIDÊNCIAS: Foi encontrada uma meta-análise que avaliou dieta hipoproteica suplementada com ceto-análogos (aminoácidos essenciais + ceto-análogos) contra dieta hipoproteica. Não houve diferença estatisticamente significante para taxa de filtração glomerular (TFG) entre os dois grupos. CONCLUSÕES: Há a necessidade de mais estudos, com maior número de pacientes e tempo de acompanhamento, que avaliem o uso dos ceto-análogos juntamente com a dieta hipoproteica e os metabólitos tóxicos, como desfecho, em comparação direta.

Mass spectrometric characterization of 4-oxopentanoic acid and gas-phase ion fragmentation mechanisms studied using a triple quadrupole and time-of-flight analyzer hybrid system and density functional theory.

4-Oxopentanoic acid was characterized experimentally by electrospray ionization using a triple quadrupole and time-of-flight analyzer hybrid system. This compound was chosen as a model substance for small organic compounds bearing an acetyl and a carboxyl group. Collision-induced dissociation experiments at different activation energies were performed to elucidate possible fragmentation pathways. These pathways were also studied on the theoretical level using density functional theory (DFT) B3LYP/6-311++G(3df,3pd)//B3LYP/6-31+G(d)+ZPVE calculations. CO2 ejection from the [M-H](-) anion of 4-oxopentanoic acid was observed and the fragmentation pathway studied by DFT reveals a new concerted mechanism for CO2 elimination accompanied by an intramolecular proton transfer within a pentagonal transition state structure. Successive elimination of water and CO from the [M-H](-) anion of 4-oxopentanoic acid was also observed. A rearrangement in the primary deprotonated ketene anion produced after water elimination was found on the theoretical level and leads to CO elimination from the primary product anion [M-H-H2O](-). Energy diagrams along the reaction coordinates of the fragmentation pathways are presented and discussed in detail. Mulliken charge distributions of some important structures are presented.

Pancreatic beta and alpha cells are both decreased in patients with fulminant type 1 diabetes: a morphometrical assessment.

AIMS/HYPOTHESIS: We have previously reported that fulminant type 1 diabetes is characterised by an absence of diabetes-related antibodies and a remarkably abrupt onset. However, little is known about the mechanism of beta cell destruction in this diabetes subtype, and to obtain insights into the aetiology of the disease, we investigated residual endocrine cells and the expression of Fas and Fas ligand in fulminant type 1 diabetes. METHODS: Residual beta and alpha cells were morphologically assessed in pancreatic tissue obtained by biopsy from five patients with recent-onset fulminant type 1 diabetes and five patients with recent-onset typical autoimmune type 1 diabetes. In addition, the expression of Fas and Fas ligand was evaluated by immunohistochemistry. RESULTS: In fulminant type 1 diabetes, beta and alpha cell areas were decreased significantly, compared with autoimmune type 1 diabetes and control subjects. In contrast, the alpha cell area was not decreased significantly in autoimmune type 1 diabetes, compared with that in control subjects. No Fas expression in islets and Fas ligand expression in CD3(+) cells in the exocrine pancreas were found in the fulminant type 1 diabetic patients who underwent this evaluation. CONCLUSIONS/INTERPRETATION: Our study showed that beta and alpha cells are damaged in fulminant type 1 diabetes. In addition to the lack of Fas and Fas ligand expression, the results suggest that the mechanism of beta cell destruction in fulminant type 1 diabetes is different from that in autoimmune type 1 diabetes.

Methodological characterization of the 2-keto [1-13C]isocaproate breath test to measure in vivo human mitochondrial function: application in alcoholic liver disease assessment.

BACKGROUND: The 2-keto[1-13C]isocaproate oxidation measurement has been shown as a helpful tool in the in vivo assessment of liver mitochondrial function. METHODS: The aim of this work was to study the variability of the 2-keto[1-13C]isocaproate breath test in 24 healthy controls (8 men and 16 women) and to evaluate its clinical usefulness in 20 patients (14 men and 6 women) with liver disease (7 men with history of alcoholism). Breath test was performed by measuring 13CO2 enrichment in breath before and after the oral administration of the tracer and by using isotope ratio mass spectrometry. RESULTS: The intrasubject and intersubject variability of the percentage of tracer oxidized were 8 and 14%, respectively. The 2-keto[1-13C]isocaproate oxidation in women was faster (p = 0.004) and tended to be higher (p = 0.050) than in men. The percentage of oxidized tracer was lower in those patients with alcoholic liver disease than in healthy volunteers (p = 0.001) and in nonalcoholic patients (p = 0.003). CONCLUSIONS: The percentage of tracer oxidized appears as a convenient parameter to detect impairment in liver mitochondrial oxidation related to alcoholism by the 2-keto[1-13C]isocaproate breath test, establishing different cutoff values depending on gender.

In vivo assessment of the mitochondrial response to caloric restriction in obese women by the 2-keto[1-C]isocaproate breath test.

The 2-keto[1-(13)C]isocaproate breath test has been proposed as a tool to detect mitochondrial dysfunction in alcoholic liver disease. The aim of this study was to evaluate if the 2-keto[1-(13)C]isocaproate breath test could detect in vivo dynamic changes on mitochondrial activity due to caloric restriction in obese women. Fifteen obese women (body mass index [BMI] > 30 kg/m(2)) participated in the study at baseline. Ten of these women agreed to participate on a diet program to induce body weight loss. Fifteen lean women (BMI < 25 kg/m(2)) were included as a control group. The breath test was performed by the oral administration of the tracer measuring (13)CO(2) enrichment in breath before and after ingestion using isotope ratio mass spectrometry. Body composition, resting energy expenditure, and plasma levels of insulin and leptin were measured. There were no relationships observed between the 2-keto[1-(13)C]isocaproate breath test and the plasma insulin (before diet: P =.863; after diet: P =.879), or leptin (before diet: P =.500; after diet: P =.637). In obese women before treatment, kilograms of fat free mass (P =.108), resting energy expenditure adjusted for body composition (P =.312), and the 2-keto[1-(13)C]isocaproate breath test (P =.205) were similar in comparison to lean women. However, 2-keto[1-(13)C]isocaproate oxidation tended to increase after dieting and was significantly higher than in controls (P =.015). These data suggest that the 2-keto[1-(13)C]isocaproate breath test reflected the adaptive modifications in mitochondrial oxidation in response to caloric restriction in obese women.

Serum insulin-like growth factor 1 level and nutritional assessment in nondialytic patients with chronic renal failure.

AIM: In order to understand the nutritional status of nondialytic patients with chronic renal failure (CRF), nutritional assessment was made in 20 nondialytic patients (15 males and 5 females; mean age 43.7 +/- 15.1 years). METHODS: Twenty CRF inpatients were selected for nutritional assessment, and 20 normal subjects served as controls. The serum insulin-like growth factor 1 (IGF-1) concentration was measured by ELISA. Serum albumin, prealbumin, and transferrin levels were also determined. RESULTS: The mean IGF-I and transferrin levels in the CRF patients were significantly lower than those in normal subjects (IGF-1: 176.2 +/- 92.5 microg/l vs. 266.7 +/- 101.7 microg/l, p < 0.01; transferrin: 2.57 +/- 0.58 g/l vs. 3.18 +/- 0.27 g/l, p < 0.05). The IGF-1 levels in 7 patients with a serum albumin concentration <40.0 g/l were significantly lower than those in 13 patients with a serum albumin concentration >40.0 g/l (95.6 +/- 42.4 microg/l vs. 219.6 +/- 82.7 microg/l, p < 0.01). The IGF-1 levels in cases treated with alpha-ketoacid were higher than in those without alpha-ketoacid treatment. The IGF-1 levels were positively correlated with creatinine clearance (r = 0.7066, p < 0.01) and serum transferrin concentration (r = 0.5347, p < 0.05). CONCLUSIONS: The fact that serum IGF-1 was correlated with serum transferrin and creatinine clearance suggests that IGF-1 may be a good indicator for assessing the nutritional status of CRF patients. The serum IGF-1 level in CRF patients is probably lower than that in normal subjects and could be improved by nutritional therapy.

Energy expenditure following oral glucose load in ten uremic patients before and after three months on a ketoacid-supplemented very-low-protein diet.

We have previously shown that a ketoacid-supplemented very-low-protein diet (KSVLPD), which has been proposed to slow down the rate of progression of chronic renal failure (CRF), improves tissue insulin sensitivity and decreases hyperinsulinemia in predialytic uremic patients. However, this diet may interfere with nutritional status. The aim of this study was to study basal energy expenditure (EE) and EE after an oral glucose load in patients with CRF before and during a KSVLPD (0.3 cal x kg wt(-1) x d(-1) supplemented with aminoacid and ketoanalogs) using oral glucose loading in combination with indirect calorimetry. We also monitored body weight and analyzed body composition by dual-energy x-ray (DEXA) during KSVLPD. In the third month of KSVLPD, no significant change in total body weight was observed, but DEXA showed a decrease in lean tissue mass (LTM; 46.2 +/- 3.6 kg before v 44 +/- 3.4 kg in the third month; P <.01) and an increase in body fat mass (20.1 +/- 2.4 kg before v 21.3 +/- 2.4 kg on KSVLPD; P <.05). Postabsorptive plasma glucose level was significantly lower, and glucose oxidation and energy expenditure per LTM were significantly increased (EE, 20 +/- 0.8 cal x kg LTM(-1) x min(-1) before diet v 21.9 +/- 1.1 cal x kg LTM(-1) x min(-1) after 3 months on KSVLPD; P <.01). Plasma glucose and serum insulin levels were significantly lower after glucose loading, and glucose oxidation increased. EE values were significantly higher after the oral glucose load, and cumulative EE after oral load increased from 20.7 +/- 0.7 cal x kg LTM(-1) x min(-1) before the diet to 22.9 +/- 1.1 cal x kg LTM(-1) x min(-1) in the third month of KSVLPD; P <.001). Glucose oxidation was higher and cumulative glucose storage was decreased after diet (29.6 +/- 4.2 g v 20.9 +/- 3.4 g on KSVLPD; P <.01). We conclude that KSVLPD increases EE in the postabsorptive state and after an oral glucose load with an adaptation of lean tissue mass in the third month of the diet. Therefore, during KSVLPD, strict monitoring of dietetic management is necessary to maintain energy requirements at high levels appropriate to the new EE.

Assessment of whole body L-leucine oxidation by noninvasive L-[1-13C]leucine breath tests: a reappraisal in patients with maple syrup urine disease, obligate heterozygotes, and healthy subjects.

Suitability of a recently proposed noninvasive L-[13C]leucine breath test for assessment of whole body leucine oxidation in maple syrup urine disease (MSUD) was examined. Oral L-[1-13C]leucine loads (38 micromol/kg body weight) were performed in overnight fasted MSUD patients (n = 6, classical form), obligate heterozygote parents (n = 6), and control subjects (n = 10). Three-hour 13CO2 exhalation kinetics were evaluated using curve fitting procedures. Venous blood was obtained in most cases and analyzed for 13C-labeled plasma metabolites. In control subjects, maximal 13CO2 exhalation was reached at tmax = 55 +/- 18 min. Cumulative 13CO2 output at 3 h amounted to 4.7 +/- 0.7 micromol x (kg body weight)(-1). Estimated total 3CO2 exhalation was 7.2 +/- 1.4 micromol x (kg body weight)(-1) (19.0 +/- 3.6% of the dose). Half of this amount was expired at t1/2 = 130 +/- 18 min. The data show a considerable degree of intersubject variability. Intraindividual variability was comparable, however, when checked in two volunteers. In obligate heterozygotes, 13CO2 kinetics were similar to controls (tmax = 35 +/- 8 min, t1/2 = 95 +/- 16 min). Total 13CO2 output [5.7 +/- 1.4 micromol x (kg body weight)(-1)] tended to be in the lower control range. None of the MSUD patients under study exhibited a significant increase in 13CO2 output after load. Maximal increase of label in plasma 4-methyl-2-oxopentanoate, the physiologic precursor of 13CO2, was 16.1 +/- 3.5 MPE in control subjects. In MSUD, label dilution was increased and correlated with the patients' leucine/4-methyl-2-oxopentanoate plasma levels. Considering the generally high variability of 13CO2 output and the unstable substrate pools in MSUD, we discuss the limitations of whole body leucine oxidation measurements by noninvasive approaches.

Noninvasive assessment of the effect of xenobiotics on mitochondrial function in human beings: studies with acetylsalicylic acid and ethanol with the use of the carbon 13-labeled ketoisocaproate breath test.

Studies in experimental animals and morphologic data in patients suggest that mitochondria are a prime target of the toxicity of ethanol and acetylsalicylic acid. However, the effects of socially consumed amounts of ethanol and therapeutic doses of acetylsalicylic acid on mitochondrial function in human beings are not known. The alpha-ketoisocaproic acid (KICA) breath test noninvasively assesses a mitochondrial function, the decarboxylation of KICA, by following the exhalation of labeled carbon dioxide after the administration of labeled KICA. The decarboxylation of I-[13C]KICA was measured in two groups of eight healthy volunteers after ingestion of 0.5 gm/kg of ethanol or 30 mg/kg of acetylsalicylic acid, respectively. Breath samples were collected at intervals for the determination of [13C] carbon dioxide in breath. The ingestion of ethanol resulted in peak concentrations of ethanol in plasma of 17.3 +/- 2.4 mmol/L (mean +/- 95% confidence interval) and increased the lactate/pyruvate ratio in peripheral venous blood. Although the 13C enrichment of circulating KICA and leucine were similar in the presence and absence of ethanol, the decarboxylation KICA was significantly lower (p < 0.01) at each time point in the presence of ethanol. The fraction decarboxylated in 2 hours was 6.3% +/- 1.9% of the administered dose after administration of ethanol and 14.2% +/- 3.9% (p < 0.001) in the control period. In contrast, the ingestion of acetylsalicylic acid, which resulted in plasma concentrations of 0.9 mmol/L salicylate significantly increased the decarboxylation of KICA to 19.3% +/- 3.1% of the administered dose exhaled in 2 hours.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of cortisol on energy expenditure and amino acid metabolism in humans.

Hydrocortisone was infused overnight into nine normal healthy adults on three occasions at 0, 80, and 200 micrograms.kg-1.h-1, producing plasma cortisol concentrations of 10.6 +/- 1.2, 34.0 +/- 2.0, and 64.9 +/- 4.3 micrograms/dl, respectively. L-[1-13C]leucine, L-[phenyl-2H5]phenylalanine, and L-[2-15N]glutamine were infused during the last 7 h of hypercortisolemia to measure amino acid kinetics. During the last 3.5 h, somatostatin, glucagon, and insulin were infused to reduce the cortisol-induced elevation in plasma insulin to basal. Hypercortisolemia increased plasma glucose, free fatty acid (FFA), and insulin concentrations. Institution of the somatostatin clamp returned insulin to basal but increased glucose and FFA. Acute hypercortisolemia increased protein breakdown 5-20%, as measured by increases in leucine and phenylalanine appearance rates. Normalizing insulin during hypercortisolemia did not alter phenylalanine flux but enhanced leucine appearance rate, the latter result indicating that insulin was affecting leucine metabolism during hypercortisolemia. The fraction of the leucine flux that was oxidized was not significantly increased with hypercortisolemia, but disposal by the nonoxidative route of leucine uptake for protein synthesis was increased. Hypercortisolemia increased cycling of amino acids by increasing protein breakdown and synthesis, but the increase in this process could have increased resting energy expenditure (REE) only 1-2%. Hypercortisolemia increased glutamine flux in a dose-dependent fashion through an increase in de novo synthesis, which presumably reflects increased release from skeletal muscle. Hypercortisolemia increased REE 9-15% at the 80 and 200 micrograms.kg-1.h-1 infusion rates. Respiratory quotient did not rise with cortisol infusion but tended to decrease, suggesting that the increase in REE was fueled by increased oxidation of fat. These data demonstrate that hypercortisolemia increases metabolic rate and may be in part responsible for the hypermetabolic state in injury.

[A substitute treatment for dialysis?]. / Tratamiento sustitutivo de la diálisis?

One of the major problems regarding the administration of amino acids by intravenous feeding is the use of racemic mixtures that are forbidden by the pharmacological regulations; other current problems is the high cost of obtaining pure amino acids. Because of this, our group has been working in the obtention of L-amino acids (assimilables by living organisms) and ketoacids (used by the body as precursors of racemic amino acid mixtures) in a less expensive and simpler way, with the aim of using these products for different pathologies.

Empirical assessment of model validity.

The metabolism of amino acids is far more complicated than a 1- to 2-pool model. Yet, these simple models have been extensively used with many different isotopically labeled tracers to study protein metabolism. A tracer of leucine and measurement of leucine kinetics has been a favorite choice for following protein metabolism. However, administering a leucine tracer and following it in blood will not adequately reflect the complex multi-pool nature of the leucine system. Using the tracer enrichment of the ketoacid metabolite of leucine, alpha-ketoisocaproate (KIC), to reflect intracellular events of leucine was an important improvement. Whether this approach is adequate to follow accurately leucine metabolism in vivo or not has not been tested. From data obtained using simultaneous administration of leucine and KIC tracers, we developed a 10-pool model of the in vivo leucine-KIC and bicarbonate kinetic system. Data from this model were compared with conventional measurements of leucine kinetics. The results from the 10-pool model agreed best with the simplified approach using a leucine tracer and measurement of KIC enrichment.

Assessment of mitochondrial function in vivo with a breath test utilizing alpha-ketoisocaproic acid.

A breath test to assess hepatic mitochondrial function in vivo was evaluated in rats. Following the i.p. administration of [1-14C]-alpha-ketoisocaproic acid, 14CO2 exhalation reached a peak within 10 to 20 min and then declined exponentially, with a half-life of 14.3 min. Control animals exhaled 38.6% of the administered radioactivity within 1 hr. In functionally anhepatic animals, 14CO2 in breath amounted to 23% of that in control animals, indicating that alpha-ketoisocaproic acid decarboxylation reflects mainly hepatic mitochondrial function in vivo. Ethanol (3 gm per kg) significantly decreased alpha-ketoisocaproic acid decarboxylation (21.8% of the dose appearing in breath in 1 hr), probably due to the ethanol-induced shift in the NAD+:NADH ratio. In contrast, an uncoupler of mitochondrial respiration, sodium salicylate (375 mg per kg), increased the decarboxylation of alpha-ketoisocaproic acid (56.3% of the dose recovered as 14CO2 in 1 hr). Mitochondrial damage induced by 4-pentenoic acid decreased the decarboxylation of alpha-ketoisocaproic acid but did not affect the microsomal metabolism of antipyrine. The present data indicate that the alpha-ketoisocaproic acid breath test provides a noninvasive estimate of hepatic mitochondrial function in vivo which, when applied to man, might yield clinically useful information.

Terapia economizadora de proteínas no pós-operatório: efeitos experimentais do alfa-ceto-isocaproato / Postoperative protein sparing therapy: effects of alpha-keto-isocaproate

Os autores avaliaram experimentalmente em coelhos, os efeitos da infusäo do alfa-ceto-isocaproato na excreçäo urinária de nitrogênio no pós-operatório. A pesquisa foi realizada em três grupos de oito animais que após serem submetidos à laparotomia com manipulaçäo das alças intestinais, receberam no pós-operatório soluçäo salina, glicose a 5% e uma soluçäo contendo 1 mg/Kg de alfa-ceto-isocaproato. A quantificaçäo da perda urinária de nitrogênio pelo método Kjeldahl mostrou-se significativamente menor no grupo que recebeu o isocaproato quando comparada com os grupos salina e glicose. Com base nos dados da experimentaçäo os autores concluíram que o isocaproato apresenta um efeito de poupança de proteína refletido por uma excreçäo urinária de nitrogênio menor que quando se faz infusäo de soluçäo salina e glicose a 5% no pós-operatório

Assessment of effects of amino acids and branched chain keto acids on leucine oxidation in human lymphocytes.

Effects of amino acids and branched chain keto acids on leucine transamination and oxidation were assessed in peripheral human lymphocytes. Isoleucine (80-200 mumol/l) and valine (250-500 mumol/l) diminished transamination and oxidation of leucine up to 25%, glutamine (50-1000 mumol/l) up to 55%. alpha-Ketoisocaproic acid (KIC; 200 mumol/l) augmented the activity state of branched chain keto acid dehydrogenase by 40%. It is concluded that in peripheral human lymphocytes (1) isoleucine, valine and glutamine are physiological inhibitors of leucine catabolism, and (2) leucine can promote its own degradation via KIC.