Kegg Pathway: Amino Acid Metabolism

Environ Sci Technol. 2009 Nov 19;
Jang HJ, Nde C, Toghrol F, Bentley WE

Mycobacterium bovis BCG strain Pasteur 1173P2 responds with adaptive and protective strategies against oxidative stress. Despite advances in our understanding of the responses to oxidative stress in many specific cases, the connectivity between targeted protective genes and the rest of cell Metabolism remains obscure. This study was therefore carried out to investigate the genome-wide response of M. bovis BCG to hydrogen peroxide after 10 and 60 min of treatment. ATP measurements were carried out in order to monitor the changes in M. bovis BCG growth over a 1 h period. The furA gene in Mycobacterium bovis, a pleiotropic regulator that couples iron Metabolism to the oxidative stress response was involved in the response to hydrogen peroxide stress. There were also increased levels of catalase/ peroxidase (KatG) and the biosynthesis operon of mycobactin. This study revealed significant upregulation of the oxidative response group of M. bovis, Amino Acid transport and Metabolism, defense mechanisms, DNA replication, recombination and repair, and downregulation of cell cycle control, mitosis, and meiosis, lipid transport and Metabolism, and cell wall/membrane biogenesis. This study shows that the treatment of M. bovis BCG with hydrogen peroxide induces iron acquisition related genes and oxidative stress response genes within one hour of treatment.

Plant Mol Biol. 2009 Nov 19;
Chao WS, Serpe MD

Underground adventitious buds of leafy spurge (Euphorbia esula) undergo three well-defined phases of dormancy, para-, endo-, and ecodormancy. In this study, relationships among genes involved in carbohydrate Metabolism and bud dormancy were examined after paradormancy release (growth induction) by decapitation and in response to seasonal signals. Real-time PCR was used to determine the expression levels of carbohydrate Metabolism genes at different phases of bud dormancy. Among differentially-regulated genes, expression of a specific Euphorbia esula beta-amylase gene (Ee-BAM1) increased 100-fold after growth induction and 16,000-fold from July (paradormancy) to December (ecodormancy). Sequence data analysis indicated that two genes, Ee-BAM1 and Ee-BAM2, could encode this beta-amylase. However, real-time PCR using gene-specific primer pairs only amplified Ee-BAM1, indicating that Ee-BAM2 is either specific to other organs or not abundant. The deduced Amino Acid sequences of these two genes are very similar at the N-terminal but differ at the C-terminal. Both contain a nearly identical, predicted 48-Amino Acid plastid transit peptide. Immunoblot analyses identified a 29 kD (mature Ee-BAM1 after cleavage of the transit peptide) and a 35 kD (unprocessed EeBAM1) protein. Both 35 and 29 kD proteins were constitutively expressed in growth-induced and seasonal samples. Immunolocalization indicated that Ee-BAM1 is in the cytosol of cells at the shoot tip of the bud. Ee-BAM1 also surrounds the amyloplasts in mature cells toward the base of the bud. These observations suggests that Ee-BAM1 may have dual functions; serving as reserve protein in the cytosol and as a degrading enzyme at the surface of amyloplasts.

Plant Mol Biol. 2009 Nov 19;
Huang S, Taylor NL, Narsai R, Eubel H, Whelan J, Millar AH

Complex II plays a central role in mitochondrial Metabolism as a component of both the electron transport chain and the tricarboxylic Acid cycle. However, the composition and function of the plant enzyme has been elusive and differs from the well-characterised enzymes in mammals and bacteria. Herewith, we demonstrate that mitochondrial Complex II from Arabidopsis and rice differ significantly in several aspects: (1) Stability-Rice complex II in contrast to Arabidopsis is not stable when resolved by native electrophoresis and activity staining. (2) Composition-Arabidopsis complex II contains 8 subunits, only 7 of which have homologs in the rice genome. SDH 1 and 2 subunits display high levels of Amino Acid identity between two species, while the remainder of the subunits are not well conserved at a sequence level, indicating significant divergence. (3) Gene expression-the pairs of orthologous SDH1 and SDH2 subunits were universally expressed in both Arabidopsis and rice. The very divergent genes for SDH3 and SDH4 were co-expressed in both species, consistent with their functional co-ordination to form the membrane anchor. The plant-specific SDH5, 6 and 7 subunits with unknown functions appeared to be differentially expressed in both species. (4) Biochemical regulation -succinate-dependent O(2) consumption and SDH activity of isolated Arabidopsis mitochondria were substantially stimulated by ATP, but a much more minor effect of ATP was observed for the rice enzyme. The ATP activation of succinate-dependent reduction of DCPIP in frozen-thawed and digitonin-solubilised mitochondrial samples, and with or without the uncoupler CCCP, indicate that the differential ATP effect on SDH is not via the protonmotive force but likely due to an allosteric effect on the plant SDH enzyme itself, in contrast to the enzyme in other organisms.

Am J Physiol Regul Integr Comp Physiol. 2009 Nov 18;
Epperson LE, Rose JC, Carey HV, Martin SL

Hibernators are unique among mammals in their ability to survive extended periods of time with core body temperatures near freezing and with dramatically reduced heart, respiratory and metabolic rates in a state known as torpor. In order to gain insight into the molecular events underlying this remarkable physiological phenotype, we applied a proteomic screening approach to identify liver proteins that differ between summer active (SA) and the entrance (Ent) phase of winter hibernation in 13-lined ground squirrels. The relative abundance of 1600 protein spots separated on 2D gels was quantitatively determined using fluorescence Difference Gel Electrophoresis (DiGE) and 74 unique proteins exhibiting significant differences between the two states were identified using liquid chromatography followed by tandem mass spectrometry (LC-MS/MS). Proteins elevated in Ent hibernators included liver fatty Acid binding protein, fatty Acid transporter and 3-hydroxy-3-methylglutaryl CoA synthase, which support the known metabolic fuel switch to lipid and ketone body utilization in winter. Several proteins involved in protein stability and protein folding were also elevated in Ent, agreeing with previous work. In contrast to transcript screening results, there was a surprising increase in the abundance of proteins involved in protein synthesis during Ent hibernation, including several initiation and elongation factors. This finding, coupled with decreased abundance of numerous proteins involved in Amino Acid and nitrogen Metabolism, supports the intriguing hypothesis that protein preservation and re-synthesis is a mechanism used by hibernating ground squirrels to help avoid nitrogen toxicity and ensure preservation of essential Amino Acids throughout the long winter fast. Key words: Ictidomys tridecemlineatus, Metabolism, starvation, TCA cycle.

Clin Sci (Lond). 2009; 118(5): 341-349
Newsholme P, Homem De Bittencourt PI, O' Hagan C, De Vito G, Murphy C, Krause MS

It is now widely accepted that hypertension and endothelial dysfunction are associated with an insulin-resistant state and thus with the development of T2DM (Type 2 diabetes mellitus). Insulin signalling is impaired in target cells and tissues, indicating that common molecular signals are involved. The free radical NO* regulates cell Metabolism, insulin signalling and secretion, vascular tone, neurotransmission and immune system function. NO* synthesis is essential for vasodilation, the maintenance of blood pressure and glucose uptake and, thus, if levels of NO* are decreased, insulin resistance and hypertension will result. Decreased blood levels of insulin, increased AngII (angiotensin II), hyperhomocysteinaemia, increased ADMA (asymmetric omega-NG,NG-dimethylarginine) and low plasma L-arginine are all conditions likely to decrease NO* production and which are associated with diabetes and cardiovascular disease. We suggest in the present article that the widely reported beneficial effects of exercise in the improvement of metabolic and cardiovascular health are mediated by enhancing the flux of muscle- and kidney-derived Amino Acids to pancreatic and vascular endothelial cells aiding the intracellular production of NO*, therefore resulting in normalization of insulin secretion, vascular tone and insulin sensitivity. Exercise may also have an impact on AngII and ADMA signalling and the production of pro- and anti-inflammatory cytokines in muscle, so reducing the progression and development of vascular disease and diabetes. NO* synthesis will be increased during exercise in the vascular endothelial cells so promoting blood flow. We suggest that exercise may promote improvements in health due to positive metabolic and cytokine-mediated effects.

Curr Microbiol. 2009 Nov 17;
Tang P, Hseu YC, Chou HH, Huang KY, Chen SC

Cyanide has been proved to be degraded by Klebsiella oxytoca. In order to examine the physiological responses of cyanide degradation by this bacterium, two-dimensional (2-DE) electrophoresis approach and MALDI-TOF-MS allow us to identify 106 proteins spots that were significantly altered in the presence of 1 mM cyanide in relative to that in 1 mM ammonia when K. oxytoca grown at the late-log phase. Among them, 27 proteins were successfully identified. These proteins were involved in carbohydrate Metabolism, nucleotide Metabolism, Amino Acid Metabolism, nitrogen Metabolism, stress responses, oxidation-reduction reactions, transporters, and miscellaneous function. Some proteins related with regulation of nitrogen assimilation pathways (glutamine synthetase), oxidative stress repairing (catalase), and protection (neutral trehalase and glycosyltransferase) could improve the effectiveness of cyanide biodegradation. Although the nitrogenase was suggested to participate in cyanide degradation in our previous study, this enzyme induction was not observed as expected. These findings could provide new insights into the inducible mechanisms underlying the capacity of K. oxytoca to tolerate cyanide stress.

Calcif Tissue Int. 2009 Nov 17;
Kanakamani J, Tomar N, Kaushal E, Tandon N, Goswami R

Vitamin D-dependent rickets type II (VDDR-type II) is a rare disorder caused by mutations in the vitamin D receptor (VDR) gene. Here, we describe a patient with VDDR-type II with severe alopecia and rickets. She had hypocalcemia, hypophosphatemia, secondary hyperparathyroidism, and elevated serum alkaline phosphatase and 1,25-dihydroxyvitamin D(3). Sequence analysis of the lymphocyte VDR cDNA revealed deletion mutation c.716delA. Sequence analysis of her genomic DNA fragment amplified from exon 6 of the VDR gene incorporating this mutation confirmed the presence of the mutation in homozygous form. This frameshift mutation in the ligand binding domain (LBD) resulted in premature termination (p.Lys240Argfs) of the VDR protein. The mutant protein contained 246 Amino Acids, with 239 normal Amino Acids at the N terminus, followed by seven changed Amino Acids resulting in complete loss of its LBD. The mutant VDR protein showed evidence of 50% reduced binding with VDR response elements on electrophoretic mobility assay in comparison to the wild-type VDR protein. She was treated with high-dose calcium infusion and oral phosphate. After 18 months of treatment, she gained 6 cm of height, serum calcium and phosphorus improved, alkaline phosphatase levels decreased, and intact PTH normalized. Radiologically, there were signs of healing of rickets. Her parents and one of her siblings had the same c.716delA mutation in heterozygous form. Despite the complete absence of LBD, the rickets showed signs of healing with intravenous calcium.

Plant Cell Physiol. 2009 Nov 16;
Ishikawa T, Takahara K, Hirabayashi T, Matsumura H, Fujisawa S, Terauchi R, Uchimiya H, Kawai-Yamada M

Bax inhibitor-1 (BI-1) is a cell death suppression factor widely conserved in higher plants and animals. Overexpression of Arabidopsis BI-1 (AtBI-1) in plants confers tolerance to various cell death-inducible stresses. However, apart from the cell death suppressing activity, little is known about the physiological roles of BI-1-overexpressing plants. In this study, we evaluated the effects of AtBI-1 overexpression on rice metabolome in response to oxidative stress. AtBI-1-overexpressing rice cells in suspension displayed enhanced tolerance to menadione-induced oxidative stress compared to vector control cells, whereas AtBI-1-overexpression did not influence increase of intracellular H(2)O(2) concentration or inhibition of oxidative stress-sensitive aconitase activity. Capillary electrophoresis-mass spectrometry (CE-MS)-based metabolome analysis revealed dynamic metabolic changes in oxidative-stressed rice cells, e.g., depletion of the central metabolic pathway, imbalance in redox state and energy charge, and accumulation of Amino Acids. Furthermore, comparative metabolome analysis demonstrated that AtBI-1 overexpression did not affect primary Metabolism in rice cells under normal growth condition but significantly altered metabolite composition within several distinct pathways under cell death-inducible oxidative stress. The AtBI-1-mediated metabolic alteration included recovery of redox state and energy charge, which are known as important factors for metabolic defense to oxidative stress. These observations suggest that although AtBI-1 does not affect rice Metabolism directly, rather, its cell death suppression activity leads to enhanced capacity to acclimate oxidative stress.

Pest Manag Sci. 2009 Nov 16;
Orcaray L, Igal M, Marino D, Zabalza A, Royuela M

BACKGROUND: The herbicide glyphosate inhibits the biosynthesis of aromatic Amino Acids by blocking the shikimate pathway. Imazethapyr and chlorsulfuron are two herbicides that act by inhibiting branched-chain Amino Acid biosynthesis. These herbicides stimulate secondary Metabolism derived from the aromatic Amino Acids. The aim of this study was to test if they cause any cross-effect in the Amino Acid content and if they have similar effects on the shikimate pathway.RESULTS: The herbicides inhibiting two different Amino Acid biosynthesis pathways showed a common pattern in general content of free Amino Acids. There was a general increase in total free Amino Acid content, with a transient decrease in the proportion of Amino Acids whose pathways were specifically inhibited. Afterwards, an increase in these inhibited Amino Acids was detected; this was probably related to proteolysis. All herbicides caused quinate accumulation. Exogenous application of quinate arrested growth, decreased net photosynthesis and stomatal conductance and was ultimately lethal, similarly to glyphosate and imazethapyr.CONCLUSIONS: Quinate accumulation was a common effect of the two different classes of herbicide. Moreover, exogenous quinate application had phytotoxic effects, showing that this plant metabolite can trigger the toxic effects of the herbicides. This ability to mimic the herbicide effects suggests a possible link between the mode of action of these herbicides and the potential role of quinate as a natural herbicide. Copyright (c) 2009 Society of Chemical Industry.

J Cell Physiol. 2009 Nov 13;
Zhang C, Liu C, Li D, Yao N, Yuan X, Yu A, Lu C, Ma X

Inorganic arsenic, an environmental contaminant, is known to cause cancer, developmental retardation, and many other serious diseases. Previous researches have shown that arsenic exerts its toxicity partially through generating reactive oxygen species (ROS). However, it is still not well understood how ROS links arsenic exposure to developmental retardation of preimplantation embryo. Here we demonstrate that high-level arsenite induces severe redox imbalance by decreasing the levels of glutathione and increasing the levels of ROS through the oxidative stress adaptor p66Shc, which induces apoptosis by activating the cytochrome c-caspase. In addition, low-level arsenite seriously perturbs the Metabolism of extracellular Amino Acid, especially that of the cytotoxic and antioxidative Amino Acids in preimplantation embryos, may also be the reason for developmental delay. Furthermore, An antioxidant, N-acetyl-L-cysteine, improves the development of arsenite-exposed embryos by reducing intracellular ROS and adjusting Amino Acid Metabolism, suggesting that increasing the intracellular antioxidant level may have preventive or therapeutic effects on arsenic-induced embryonic toxicity. In conclusion, we suggest that p66Shc-linked redox imbalance and abnormal extracellular Amino Acid Metabolism mediate arsenite-induced embryonic retardation. J. Cell. Physiol. (c) 2009 Wiley-Liss, Inc.

Nutr Res. 2009 Oct; 29(10): 685-95
Malinowska A, Chmurzynska A

The aim of this review is to present a general overview of the relationships among homocysteine Metabolism, polymorphism of the genes encoding homocysteine Metabolism-related enzymes, and the nutrients influencing the plasma homocysteine level. Combining these factors creates a profile of an individual's susceptibility to complex diseases associated with hyperhomocysteinemia. Homocysteine is an Amino Acid derived from the demethylation of methionine. Hyperhomocysteinemia is associated with an increased risk of several complex diseases, including cardiovascular diseases. The level of plasma homocysteine depends on the combined effects of genetic and environmental factors. Polymorphisms of genes encoding homocysteine Metabolism-related enzymes, such as methylenetetrahydrofolate reductase, methionine synthase, methionine synthase reductase, and cystathionine beta-synthase, influence plasma homocysteine concentration and thereby cardiovascular health. On the other hand, homocysteine Metabolism may be modulated by dietary intake of the nutrients involved in homocysteine Metabolism (ie, folates, vitamin B(6), and vitamin B(12)). Thus, the appropriate health-promoting doses of these nutrients may vary among certain groups of individuals, depending on their genotypes and other risk factors for complex diseases. Better understanding of the relationship between genotype and nutrition influencing the plasma total homocysteine level and cardiovascular health may improve the cardiovascular diagnostic tests (ie, measurement of biologic markers). It could be possible to define the level of progression, severity, and susceptibility to disease much earlier than it is done now. In conclusion, the introduction of combined dietary and pharmacologic treatment would be possible at the initial stages of disease.

BMC Genomics. 2009 Nov 16; 10(1): 527
Schwarzenberger A, Courts C, Von Elert E

ABSTRACT: BACKGROUND: Two major biological stressors of freshwater zooplankton of the genus Daphnia are predation and fluctuations in food quality. Here we use kairomones released from a planktivorous fish (Leucaspius delineatus) and from an invertebrate predator (larvae of Chaoborus flavicans) to simulate predation pressure; a microcystin-producing culture of the cyanobacterium Microcystis aeruginosa and a microcystin-deficient mutant are used to investigate effects of low food quality. Real-time quantitative polymerase chain reaction (QPCR) allows quantification of the impact of biotic stressors on differential gene activity. The draft genome sequence for Daphnia pulex facilitates the use of candidate genes by precisely identifying orthologs to functionally characterized genes in other model species. This information is obtained by constructing phylogenetic trees of candidate genes with the knowledge that the Daphnia genome is composed of many expanded gene families. RESULTS: We evaluated seven candidate reference genes for QPCR in Daphnia magna after exposure to kairomones. As a robust approach, a combination normalisation factor (NF) was calculated based on the geometric mean of three of these seven reference genes: glyceraldehyde-3-phosphate dehydrogenase, TATA-box binding protein and succinate dehydrogenase. Using this NF, expression of the target genes actin and alpha-tubulin were revealed to be unchanged in the presence of the tested kairomones. The presence of fish kairomone up-regulated one gene (cyclophilin) involved in the folding of proteins, whereas Chaoborus kairomone down-regulated the same gene. We evaluated the same set of candidate reference genes for QPCR in Daphnia magna after exposure to a microcystin-producing and a microcystin-free strain of the cyanobacterium Microcystis aeruginosa. The NF was calculated based on the reference genes 18S ribosomal RNA, alpha-tubulin and TATA-box binding protein. We found glyceraldehyde-3-phosphate dehydrogenase and ubiquitin conjugating enzyme to be up-regulated in the presence of microcystins in the food of D. magna. These findings demonstrate that certain enzymes of glycolysis and protein catabolism are significantly upgregulated when daphnids ingest microcystins. Each differentially regulated gene is a member of an expanded gene family in the D. pulex genome. The cyclophilin, GapDH and UBC genes show moderately large sequence divergence from their closest paralogs. Yet actin and alpha-tubulin genes targeteted by our study have nearly identical paralogs at the Amino Acid level. CONCLUSIONS: Gene expression analysis using a normalisation factor based on three reference genes showed that transcription levels of actin and alpha-tubulin were not substantially changed by predator-borne chemical cues from fishes or invertebrates, although changes in expression on the protein level were shown elsewhere. These changes in protein level could be caused by others than the investigated paralogs, showing the importance of the construction of phylogenetic trees for candidate gene approaches. However, fish kairomones caused an up-regulation, and Chaoborus kairomone caused a down-regulation of cyclophylin, which proved to be a potential target gene for further analysis of kairomone effects on the life history of daphnids. Changes in food quality required a different set of reference genes compared to the kairomone experiment. The presence of dietary microcystins led to an up-regulation of two genes involved in the basic Metabolism of D. magna, i.e. glyceraldehyde-3-phosphate dehydrogenase and ubiquitin conjugating enzyme, which suggests that microcystins in cyanobacteria have more general effects on the Metabolism of D. magna than previously thought. Phylogenetic trees resolving relationships among paralogs that share the same gene name are shown to be important for determining the identity of the candidate genes under investigation.

Thyroid. 2009 Nov 16;
Montanelli L, Agretti P, Marco GD, Bagattini B, Ceccarelli C, Brozzi F, Lettiero T, Cerbone M, Vitti P, Salerno M, Pinchera A, Tonacchera M

Background: Iodide transport defects (ITDs), rare causes of congenital hypothyroidism (CH), have been shown to arise from abnormalities of the sodium/iodide symporter (NIS). We describe a 16-year-old girl with CH caused by an ITD resulting from a novel mutation of NIS. Summary: A 16-year-old girl with CH diagnosed by a neonatal screening program received early treatment with L-thyroxine replacement therapy. A (123)I scan had failed to reveal any iodide uptake by the thyroid and salivary glands; thus, thyroid agenesis was diagnosed. Thyroglobulin (Tg) was not measured when she was a neonate or infant. Unexpectedly, at the age of 14.5 years, a nodular goiter and high serum Tg concentrations (303 ng/mL; normal, <50) were identified. Her thyroid radioactive iodine uptake was very low as was the saliva to plasma iodide ratio (0.5). Analysis of her NIS gene revealed an in-frame six-nucleotide deletion of the coding sequence (1206-1211delGTCGGC) corresponding to the deletion of Amino Acids 287 and 288 of the human NIS protein located at the beginning of the VIII transmembrane segment. The proband was homozygous for this deletion, whereas both unrelated parents and her brother were heterozygous. COS-7 cells transfected with the mutant NIS failed to concentrate iodide, confirming that the mutation was the direct cause of the ITD in this patient. Conclusions: We describe a patient with CH caused by a previously not described mutation of the NIS gene that was inherited from her parents. We therefore recommend that thyroid ultrasonography be performed in CH patients with low radioactive iodine uptake and elevated serum Tg.

Amino Acids. 2009 Nov 14;
Yuan LQ, Liu W, Cui RR, Wang D, Meng JC, Xie H, Wu XP, Zhou HD, Lu Y, Liao EY

Several studies have suggested a direct link between taurine and bone homeostasis. However, the mechanisms of taurine on the regulation of bone Metabolism have not been elucidated. Using a coculture of osteoblasts and bone marrow cells as a model for the study of osteoclastogenesis, RANKL-stimulated RAW264.7 cells and M-CSF- and RANKL-induced bone marrow macrophages were investigated to elucidate the possible roles of taurine in osteoclastogenesis. Taurine inhibited osteoclastogenesis in the coculture of osteoblasts and bone marrow cells, but did not influence the expression of OPG and RANKL in osteoblasts. The taurine transporter (TAUT) expressed by RAW264.7 and bone marrow macrophages exhibited typical taurine uptake activity. Taurine directly reduced osteoclastogenesis in RANKL-stimulated RAW264.7 cells and M-CSF- and RANKL-induced bone marrow macrophages, while TAUT siRNA relieved this effect. Our study demonstrated that taurine directly inhibited osteoclastogenesis through the taurine transporter. Taken together, these data suggest that taurine plays a direct role in bone homeostasis by inhibiting osteoclastogenesis.

Med Sci Sports Exerc. 2009 Dec; 41(12): 2158-2164
Cermak NM, Solheim AS, Gardner MS, Tarnopolsky MA, Gibala MJ

INTRODUCTION:: Ingesting protein (PRO) with CHO during prolonged exercise is purported to improve performance compared with CHO alone by altering the regulation of skeletal muscle energy provision. However, no study has directly investigated this issue. We tested the hypothesis that compared with CHO alone, coingestion of PRO would alter markers of metabolic control, including the magnitude of glycogen use and the net expansion of the tricarboxylic Acid cycle intermediate pool, which has been linked to the capacity for oxidative energy delivery. METHODS:: Eight trained men (mean +/- SE: age = 29 +/- 2 yr; V O2peak = 55 +/- 2 mL.kg.min) cycled at 69% +/- 1% V O2peak for 90 min on two occasions, and biopsy samples (vastus lateralis) were obtained before and after exercise. In a randomized, double-blind manner, subjects ingested one of two drinks during exercise that contained either 6% CHO or 6% CHO + 2% PRO (CHO + PRO) at a rate of 1 L.h to deliver 60 g.h CHO +/- 20 g.h PRO. RESULTS:: CHO + PRO ingestion increased the plasma concentration of branched chain (561 +/- 46 vs 301 +/- 32 mumol.L) and essential Amino Acids (1071 +/- 98 vs 670 +/- 71 mumol.L) after exercise versus CHO (both P values Acid cycle intermediate expansion (CHO + PRO = 2.3 +/- 0.7 vs CHO = 2.1 +/- 0.2 mmol.kg dry weight) were similar between trials. Blood creatine kinase activity and 20-km time trial performance measured approximately 24 h after the first exercise bout were not different between treatments. CONCLUSION:: When trained men ingest CHO at a rate on the upper end of the range generally recommended to improve endurance performance, coingestion of PRO does not alter specific markers proposed to reflect an enhanced capacity for skeletal muscle energy delivery.

Metabolism. 2009 Nov 13;
Filiputti E, Rafacho A, Araújo EP, Silveira LR, Trevisan A, Batista TM, Curi R, Velloso LA, Quesada I, Boschero AC, Carneiro EM

A regimen of low-protein diet induces a reduction of pancreatic islet function that is associated with development of metabolic disorders including diabetes and obesity afterward. In the present study, the influence of leucine supplementation on metabolic parameters, insulin secretion to glucose and to Amino Acids, as well as the levels of proteins that participate in the phosphatidylinositol 3-phosphate kinase (PI3K) pathway was investigated in malnourished rats. Four groups were fed with different diets for 12 weeks: a normal protein diet (17%) without (NP) or with leucine supplementation (NPL) or a low (6%)-protein diet without (LP) or with leucine supplementation (LPL). Leucine was given in the drinking water during the last 4 weeks. As indicated by the intraperitoneal glucose tolerance test, LPL rats exhibited increased glucose tolerance as compared with NPL group. Both NPL and LPL rats had higher circulating insulin levels than controls. The LPL rats also showed increased insulin secretion by pancreatic islets in response to glucose or arginine compared with those observed in islets from LP animals. Glucose oxidation was significantly reduced in NPL, LP, and LPL isolated islets as compared with NP; but no alteration was observed for leucine and glutamate oxidation among the 4 groups. Western blotting analysis demonstrated increased PI3K and mammalian target protein of rapamycin protein contents in LPL compared with LP islets. A significant increase in insulin-induced insulin receptor substrate 1-associated PI3K activation was also observed in LPL compared with LP islets. These findings indicate that leucine supplementation can augment islet function in malnourished rats and that activation of the PI3K/mammalian target protein of rapamycin pathway may play a role in this process.

Metabolism. 2009 Nov 13;
Xie Z, Li H, Wang K, Lin J, Wang Q, Zhao G, Jia W, Zhang Q

Excessive energy intake greatly contributes to the development of nonalcoholic fatty liver disease (NAFLD) in modern society. To better understand the comprehensive mechanisms of NAFLD development, we investigated the metabolic alterations of rats with NAFLD induced by high-fat diet (HFD). Male Wistar rats were fed a HFD or standard chow for control. After 16 weeks, rat serum was collected for biochemical measurement. The rats' livers were resected and subjected to histology inspection and gene expression analysis with complementary DNA microarray and metabolic analysis with gas chromatography-mass spectroscopy. In HFD rats, the serum cholesterol, triglycerides, glucose, and insulin contents were increased; and the total cholesterol and triglycerides in the livers were also significantly increased. Complementary DNA microarray analysis revealed that 130 genes were regulated by HFD. Together with real-time reverse transcriptase polymerase chain reaction, lipid Metabolism regulatory members like sterol regulatory element binding factor 1 and stearoyl-coenzyme A desaturase 1 had up-regulation, whereas others like peroxisome proliferator-activated receptor, carnitine palmitoyltransferase 1, and 3-hydroxy-3-methylglutaryl-coenzyme A reductase had repressed expression, in HFD rat livers. Metabolomic analysis showed that tetradecanoic Acid, hexadecanoic Acid, and oleic Acid had elevation and arachidonic Acid and eicosapentaenoic Acid had decreased content in HFD rat livers. Amino Acids including glycine, alanine, aspartic Acid, glutamic Acid, and proline contents were decreased. The integrative results from transcriptomic and metabolomic studies revealed that, in HFD rat livers, fatty Acid utilization through beta-oxidation was inhibited and lipogenesis was enhanced. These observations facilitated our understanding of the pathways involved in the development of NAFLD induced by HFD.

Metabolism. 2009 Nov 13;
Ponzone A, Porta F, Mussa A, Alluto A, Ferraris S, Spada M

Conflicting results have been reported concerning the efficacy of tetrahydrobiopterin (BH4), the cofactor of phenylalanine hydroxylase, for reducing phenylalanine (Phe) concentration in phenylketonuria (PKU). We aimed to test quantitatively the effects of BH4 in PKU patients. Seven fully characterized patients were selected among a population of 130 PKU subjects as harboring PKU mutations predicted as BH4 responsive and previously considered responsive to a cofactor challenge. They received a simple Phe (100 mg/kg) and 2 combined Phe (100 mg/kg) and BH4 (20 mg/kg) oral loading tests. Cofactor was administered either before or after the Amino Acid. The concentrations of Phe, tyrosine (Tyr), and biopterin were measured over 24 hours after loading. The comparative analysis of the loading tests showed that in all patients plasma Phe concentrations peaked within 3 hours, and fell within 24 hours by about 50% in benign, 20% in mild, and 15% in severe phenylalanine hydroxylase deficiency regardless of BH4 administration. A consistent or moderate increase of plasma Tyr, again independent of the cofactor challenge, was observed only in the less severe forms of PAH deficiency. Mean blood biopterin concentration increased 6 times after simple Phe and 34 to 39 times after combined loading tests. The administration of BH4 does not alter Phe and Tyr Metabolism in PKU patients. The clearance of plasma Phe after oral loading and, as well as Tyr production, is not related to cofactor challenge but to patient's phenotype. The assessment of BH4 responsiveness by the methods so far used is not reliable, and the occurrence of BH4-responsive forms of PKU still has to be definitely proven.

Clin Chim Acta. 2009 Nov 11;
Zheng S, Yu M, Lu X, Huo T, Ge L, Yang J, Wu C, Li F

BACKGROUND: Depression is a prevalent complex psychiatric disorder and its pathophysiological mechanism is not yet well understood. We investigated the metabolic profiling of urine samples from depression model rats to find potential disease biomarkers and research pathology of depression. METHODS: An animal model of depression was produced by chronic unpredictable mild stress (CUMS). Metabolic profiling of the urine was performed by using ultra performance liquid chromatography coupled to mass spectrometry (UPLC-MS). Principal component analysis (PCA) was utilized to classify and reveal the differences between the model group and control group. RESULTS: Principal component analysis displayed a clear separation between CUMS-treated rats and control rats. CUMS-treated rats were characterized by the increase of kynurenic Acid, xanthurenic Acid, phenylalanine, N(2)-succinyl-l-ornithine, hippuric Acid and phenylacetylglycine together with the decrease of tryptophan, indoxyl sulfate, indole-3-acetate, citrate, alpha-ketoglutarate and creatinine in urine. These biochemical changes are related to the disturbance in energy Metabolism, Amino Acid Metabolism and gut microflora. CONCLUSIONS: Metabonomic approach is helpful to further understanding the pathophysiology of depression and assisting in clinical diagnosis of depression.

Harv Ment Health Lett. 2009 Oct; 26(4): 7