Amino acid metabolism in pediatric patients

CLPP-Null Eukaryotes with Excess Heme Biosynthesis Show Reduced L-arginine Levels, Probably via CLPX-Mediated OAT Activation

The serine peptidase CLPP is conserved among bacteria, chloroplasts, and mitochondria. In humans and mice, its loss causes Perrault syndrome, which presents with growth deficits, infertility, deafness, and ataxia. In the filamentous fungus Podospora anserina, CLPP loss leads to longevity. CLPP substrates are selected by CLPX, an AAA+ unfoldase. CLPX is known to target delta-aminolevulinic acid synthase (ALAS) to promote pyridoxal phosphate (PLP) binding. CLPX may also influence cofactor association with other enzymes. Here, the evaluation of P. anserina metabolomics highlighted a reduction in arginine/histidine levels. In Mus musculus cerebellum, reductions in arginine/histidine and citrulline occurred with a concomitant accumulation of the heme precursor protoporphyrin IX. This suggests that the increased biosynthesis of 5-carbon (C5) chain deltaALA consumes not only C4 succinyl-CoA and C1 glycine but also specific C5 delta amino acids. As enzymes responsible for these effects, the elevated abundance of CLPX and ALAS is paralleled by increased OAT (PLP-dependent, ornithine delta-aminotransferase) levels. Possibly as a consequence of altered C1 metabolism, the proteome profiles of P. anserina CLPP-null cells showed strong accumulation of a methyltransferase and two mitoribosomal large subunit factors. The reduced histidine levels may explain the previously observed metal interaction problems. As the main nitrogen-storing metabolite, a deficiency in arginine would affect the urea cycle and polyamine synthesis. Supplementation of arginine and histidine might rescue the growth deficits of CLPP-mutant patients.

Nutritional Profiling of Wild (Pangasius pangasius) and Farmed (Pangasius hypophthalmus) Pangasius Catfish with Implications to Human Health

This study analyzed and compared the nutritional profiles of wild (Pangasius pangasius) and farmed (Pangasius hypophthalmus) pangasius catfish collected from the various sources of river and culture ponds in Bangladesh. The results indicated that the wild pangasius catfish had a significantly (p < 0.05) higher levels of moisture, fat and ash content, compared to the farmed one. However, the farmed pangasius had significantly higher level of protein and carbohydrate, compared to wild pangasius. The total EAA ratio was found to be significantly higher (p < 0.05) in wild pangasius (1.51 ± 0.01 g/100 g), compared to farmed pangasius (1.55 ± 0.01 g/100 g), which exceeded the FAO/WHO minimum standard of 40% for both species. In regard to fatty acid contents, wild pangasius was found to be rich in docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) with a mean value of 4.89% and 2.72%, respectively, while the values in the farmed pangasius were 1.07% and 0 (not detected), respectively. A higher ω-3/ω-6 ratio was found in wild pangasius 14.26%, in comparison with farmed pangasius (0.14%). Overall, the results indicated that pangasius catfish either farmed or wild are suitable for human consumption wherein wild pangasius has superior amino acid and fatty acid quality, compared to the pangasius reared in captivity.

Comparison of Hepatic Metabolite Profiles between Infant and Adult Male Mice Using 1H-NMR-Based Untargeted Metabolomics

Although age-related characteristics of hepatic metabolism are reported, those in infants are not fully understood. In the present study, we performed untargeted metabolomic profiling of the livers of infant (3-week-old) and adult (9-week-old) male ICR mice using ¹H-NMR spectroscopy and compared 35 abundant hepatic metabolite concentrations between the two groups. The liver/body weight ratio did not differ between the two groups; however, serum glucose, blood urea nitrogen, total cholesterol, and triglyceride concentrations were lower in infants than in adults. Hepatic carbohydrate metabolites (glucose, maltose, and mannose) were higher, whereas amino acids (glutamine, leucine, methionine, phenylalanine, tyrosine, and valine) were lower in infant mice than in adult mice. The concentrations of ascorbate, betaine, sarcosine, and ethanolamine were higher, whereas those of taurine, inosine, and O-phosphocholine were lower in infant mice than in adult mice. The differences in liver metabolites between the two groups could be due to differences in their developmental stages and dietary sources (breast milk for infants and laboratory chow for adults). The above results provide insights into the hepatic metabolism in infants; however, the exact implications of the findings require further investigation.

Plasma amino acid profiles in dogs with closed extrahepatic portosystemic shunts are only partially improved 3 months after successful gradual attenuation

BACKGROUND

Dogs with portosystemic shunts have an altered blood amino acid profile, with an abnormal branched-chained amino acid (BCAA)-to-aromatic amino acid (AAA) ratio being the most common abnormality. Different liver diseases have distinctive amino acid profiles.

OBJECTIVES

Determine the changes in plasma amino acid profiles in dogs with extrahepatic portosystemic shunts (EHPSS) from diagnosis to complete closure.

ANIMALS

Ten client-owned dogs with EHPSS closed after surgical attenuation.

METHODS

Prospective cohort study. Medical treatment was instituted in dogs diagnosed with EHPSS. At least 4 weeks later, gradual surgical attenuation was performed. Three months postoperatively, EHPSS closure was confirmed by transsplenic portal scintigraphy. Clinical signs were scored and blood was taken before institution of medical treatment, at time of surgery, and 3 months postoperatively. At the end of the study, the plasma amino acid profiles were analyzed in batch.

RESULTS

The median BCAA-to-AAA ratio was extremely low (0.6) at time of diagnosis and remained low (0.5) at time of surgery, despite the fact that median neurological score significantly improved from 22 to 2 after starting medical treatment (P = .04). Three months after surgical attenuation, a significantly higher BCAA-to-AAA ratio (1.5) was observed (P < .001).

CONCLUSIONS AND CLINICAL IMPORTANCE

Medical treatment does not improve the BCAA-to-AAA ratio in dogs with EHPSS, despite substantial clinical improvement. Although the ratio significantly increased after EHPSS closure, it was still indicative of moderate to severe hepatic dysfunction in all dogs.

Association of Plasma Total Cysteine and Anthropometric Status in 6-30 Months Old Indian Children

High-quality protein has been associated with child growth; however, the role of the amino acid cysteine remains unclear. The aim was to measure the extent to which plasma total cysteine (tCys) concentration is associated with anthropometric status in children aged 6–30 months living in New Delhi, India. The study was a prospective cohort study including 2102 children. We calculated Z-scores for height-for-age (HAZ), weight-for-height (WHZ), or weight-for-age (WAZ) according to the WHO Child Growth Standards. We used multiple regression models to estimate the association between tCys and the anthropometric indices. A high proportion of the children were categorized as malnourished at enrolment; 41% were stunted (HAZ ≤ −2), 19% were wasted (WHZ ≤ −2) and 42% underweight (WAZ ≤ −2). Plasma total cysteine (tCys) was significantly associated with HAZ, WHZ and WAZ after adjusting for relevant confounders (p < 0.001). Low tCys (≤25th percentile) was associated with a decrease of 0.28 Z-scores for HAZ, 0.10 Z-scores for WHZ, and 0.21 Z-scores for WAZ compared to being >25th percentile. In young Indian children from low-to-middle socioeconomic neighborhoods, a low plasma total cysteine concentration was associated with an increased risk of poor anthropometric status.

Protein and Amino Acid Content in Four Brands of Commercial Table Eggs in Retail Markets in Relation to Human Requirements

Considering the common believe that all eggs in the retail market are nutritionally similar, four different commercial sources of eggs (A, B, C, and D) available in a retail market were collected to investigate the crude protein and amino acid content, as well as the protein quality in the whole edible part of eggs (albumen + yolk), egg albumen, and egg yolk, separately. Five egg samples per source were collected four times during the experimental period, which resulted in a total number of 20 samples that were pooled to finally present five samples per source of eggs. The results show that crude protein in albumen was significantly higher in A and B than that of C and D, but the difference was found among edible parts of eggs such as yolk > whole edible part > albumen. Essential amino acids (arginine, histidine, isoleucine, lysine, methionine, methionine + cysteine, phenylalanine, phenylalanine + tyrosine, threonine, and valine) of eggs significantly differed according to the source of eggs, but eggs from different sources could provide from 17.4-26.7% of recommended daily allowance (RDA) of amino acids for adults. Essential amino acids (EAAs) were higher (p ≤ 0.05) in eggs from sources A and B than in source D, while source C exhibited intermediate values. Source B had greater (p ≤ 0.05) non-essential amino acids (NEAAs) than did sources C and D in whole edible egg, while source A displayed intermediate values. The phenylalanine + tyrosine, histidine, and lysine were the 1st, 2nd, and 3rd limiting amino acids in all sources of eggs. In conclusion, the investigated eggs showed different EAAs/NEAAs ratio and antioxidant amino acids, indicating a potential for enhancing nutritional values and extending the shelf life of eggs by different nutritional additions.

Coconut Neera—A Vital Health Beverage from Coconut Palms: Harvesting, Processing and Quality Analysis

Nature has made nutritive products in such a way that it cannot be manufactured in laboratories or in mills. Coconut Neera is the natural sap of the mature coconut palms rich with all essential nutrients, minerals and vitamins for human health. Harvesting of Neera from the spadix of the palms without disturbing the physiology of the tree has a lot of potential at the industrial scale. However, the development of alcohol in the extracted sap during tapping by auto-fermentation has given a misnomer for Neera as “sweet toddy”. Hence, the commercial popularity of Neera as a health drink has diminished at a global level. Though several traditional techniques like the usage of calcium hydroxide (lime) and the application of the chiller device during harvesting Neera from spadix have been practiced for collecting non-fermented Neera, none of the techniques were found acceptable at the commercial level. The results of the present study demonstrate the harvesting and processing procedure standardized for the collection and storage of non-fermented Neera from palms by repeated field trials. The cumulative effect of the anti-fermentation solution (AFS) with the presence of the two preservatives—citric acid (5 mM) and potassium metabisulphite (2 mM)—by preventing fermentation from the level of harvesting to processing was confirmed. The zero content of alcohol in raw Neera indicates the AFS action. The proximate composition of primary constituents and the content of minerals, amino acids and vitamins present in Neera highlights its nutrient value as a health beverage. The higher content of minerals—sodium and potassium (15.2 mg and 100 mg), the elevated level of amino acids-cysteine (14 mg), tyrosine (7.11 mg), arginine (7 mg) and the presence of vitamin C (65 mg) and vitamin A as retinol (4.88 IU)—indicates the therapeutic importance of coconut Neera. The data of oral toxicity and the glycemic index further support the vital quality.

The Jellyfish Rhizostoma pulmo (Cnidaria): Biochemical Composition of Ovaries and Antibacterial Lysozyme-like Activity of the Oocyte Lysate

Jellyfish outbreaks in marine coastal areas represent an emergent problem worldwide, with negative consequences on human activities and ecosystem functioning. However, potential positive effects of jellyfish biomass proliferation may be envisaged as a natural source of bioactive compounds of pharmaceutical interest. We investigated the biochemical composition of mature female gonads and lysozyme antibacterial activity of oocytes in the Mediterranean barrel jellyfish Rhizostoma pulmo. Chemical characterization was performed by means of multinuclear and multidimensional NMR spectroscopy. The ovaries of R. pulmo were mainly composed of water (93.7 ± 1.9% of wet weight), with organic matter (OM) and dry weight made respectively of proteins (761.76 ± 25.11 µg mg-1 and 45.7 ± 1.5%), lipids (192.17 ± 10.56 µg mg-1 and 9.6 ± 0.6%), and carbohydrates (59.66 ± 2.72 µg mg-1 and 3.7 ± 0.3%). The aqueous extract of R. pulmo gonads contained free amino acids, organic acids, and derivatives; the lipid extract was composed of triglycerides (TG), polyunsaturated fatty acids (PUFAs), diunsaturated fatty acids (DUFAs), monounsaturated fatty acids (MUFAs), saturated fatty acids (SFAs), and minor components such as sterols and phospholipids. The R. pulmo oocyte lysate exhibited an antibacterial lysozyme-like activity (mean diameter of lysis of 9.33 ± 0.32 mm corresponding to 1.21 mg/mL of hen egg-white lysozyme). The occurrence of defense molecules is a crucial mechanism to grant healthy development of mature eggs and fertilized embryos (and the reproductive success of the species) by preventing marine bacterial overgrowth. As a corollary, these results call for future investigations for an exploitation of R. pulmo biomasses as a resource of bioactive metabolites of biotechnological importance including pharmaceuticals and nutrition.

Biochemical diversity evaluation in chickpea accessions employing mini-core collection

The seeds of chickpea provide an exceptional source of dietary proteins and is one of the important legumes in both developed and developing countries over the world. The available germplasm of cultivated chickpea is deficient in desired biochemical signatures. To identify new sources of variations for breeding, reduced subsets of germplasm such as mini-core collection can be explored as an effective resource. In the present investigation, mini-core collections consisting of 215 accessions of chickpea were extensively evaluated for tapping biochemical diversity. Analysis included ten biochemical parameters comprising total protein, total free amino acids, phytic acid, tannin, total phenolics, total flavonoids, lectin, DPPH radical scavenging activity, in vitro digestibility of protein and starch. The spectrum of diversity was documented for total protein (4.60-33.90%), total free amino acids (0.092-9.33 mg/g), phytic acid (0.009-4.06 mg/g), tannin (0.232-189.63 mg/g), total phenolics (0.15-0.81 mg/g), total flavonoids (0.04-1.57 mg/g), lectin (0.07-330.32 HU/mg), DPPH radical scavenging activity (26.74-49.11%), in vitro protein digestibility (59.45-76.22%) and in vitro starch digestibility (45.63-298.39 mg of maltose/g). The principal component analysis revealed association of chickpea higher protein content to the lower level of total phenolics and flavonoid contents. The dendrogram obtained by unweighted pair group method using arithmetic average cluster analysis grouped the chickpea accessions into two major clusters. This is the first comprehensive report on biochemical diversity analysed in the mini-core chickpea accessions. The ultimate purpose of conducting such studies was to deliver information on nutritional characteristics for effective breeding programmes. Depending on the objectives of the breeding aforesaid accessions could be employed as a parent.

Soy, Soy Foods and Their Role in Vegetarian Diets

Soy is a basic food ingredient of traditional Asian cuisine used for thousands of years. In Western countries, soybeans have been introduced about a hundred years ago and recently they are mainly used for surrogate foods production. Soy and soy foods are common nutritional solutions for vegetarians, due to their high protein content and versatility in the production of meat analogues and milk substitutes. However, there are some doubts about the potential effects on health, such as the effectiveness on cardiovascular risk reduction or, conversely, on the possible disruption of thyroid function and sexual hormones. The soy components that have stimulated the most research interest are isoflavones, which are polyphenols with estrogenic properties highly contained in soybeans. In this review, we discuss the characteristics of soy and soy foods, focusing on their nutrient content, including phytoestrogens and other bioactive substances that are noteworthy for vegetarians, the largest soy consumers in the Western countries. The safety of use will also be discussed, given the growing trend in adoption of vegetarian styles and the new soy-based foods availability.

Gene editing and genetic engineering approaches for advanced probiotics: A review

The applications of probiotics are significant and thus resulted in need of genome analysis of probiotic strains. Various omics methods and systems biology approaches enables us to understand and optimize the metabolic processes. These techniques have increased the researcher's attention towards gut microbiome and provided a new source for the revelation of uncharacterized biosynthetic pathways which enables novel metabolic engineering approaches. In recent years, the broad and quantitative analysis of modified strains relies on systems biology tools such as in silico design which are commonly used methods for improving strain performance. The genetic manipulation of probiotic microorganisms is crucial for defining their role in intestinal microbiota and exploring their beneficial properties. This review describes an overview of gene editing and systems biology approaches, highlighting the advent of omics methods which allows the study of new routes for studying probiotic bacteria. We have also summarized gene editing tools like TALEN, ZFNs and CRISPR-Cas that edits or cleave the specific target DNA. Furthermore, in this review an overview of proposed design of advanced customized probiotic is also hypothesized to improvise the probiotics.

Parenteral Nutrition–Associated Cholestasis in Neonates: Multivariate Analysis of the Potential Protective Effect of Taurine

BACKGROUND

Neonates receiving parenteral nutrition (PN) are at risk for PN-associated cholestasis (PNAC); however, no preventive factors for PNAC have been clearly identified. Despite reports suggesting that taurine may prevent PNAC in neonates, such an effect of taurine has not yet been definitively demonstrated. We determined whether taurine supplementation reduces the incidence of PNAC in premature or critically ill neonates.

METHODS

This study was part of a prospective, randomized, multi-institutional trial designed to assess cholecystokinin vs placebo as a potential preventive therapy of PNAC. Taurine supplementation of PN varied between institutions. The presence or absence of taurine in PN was analyzed by multivariate analysis, with a primary outcome measure of serum conjugated bilirubin (CB) as a measure of PNAC.

RESULTS

Taurine reduced PNAC in premature infants (estimated maximum CB [95% confidence interval] 0.50 mg/dL [-0.17 to 1.18] for those receiving taurine, vs 3.45 mg/dL [1.79-5.11] for neonates not receiving taurine, approaching significance, p = .07). Taurine significantly reduced PNAC in infants with necrotizing enterocolitis (NEC; estimated maximum CB 4.04 mg/dL [2.85-5.23], NEC infants receiving taurine, vs 8.29 mg/dL [5.61-10.96], NEC infants not receiving taurine, p < .01). There were too few neonates with surgical anomalies to evaluate the effect of taurine in this group.

CONCLUSIONS

Within specific subgroups of neonatal patients, taurine supplementation does offer a very significant degree of protection against PNAC. Patients with NEC or severe prematurity are most likely to benefit substantially from taurine supplementation.

Serum Amino Acid Profiles in Childhood Predict Triglyceride Level in Adulthood: A 7-Year Longitudinal Study in Girls

CONTEXT

Branched-chain and aromatic amino acids are associated with high risk of developing dyslipidemia and type II diabetes in adults.

OBJECTIVE

This study aimed to examine whether serum amino acid profiles associate with triglyceride concentrations during pubertal growth and predict hypertriglyceridemia in early adulthood.

DESIGN

This was a 7.5-year longitudinal study.

SETTING

The study was conducted at the Health Science Laboratory, University of Jyväskylä.

PARTICIPANTS

A total of 396 nondiabetic Finnish girls aged 11.2 ± 0.8 years at the baseline participated in the study.

MAIN OUTCOME MEASURES

Body composition was assessed by dual-energy x-ray absorptiometry; serum concentrations of glucose, insulin, and triglyceride by enzymatic photometric methods; and amino acids by nuclear magnetic resonance spectroscopy.

RESULTS

Serum leucine and isoleucine correlated significantly with future triglyceride, independent of baseline triglyceride level (P < .05 for all). In early adulthood (at the age of 18 years), these amino acids were significantly associated with hypertriglyceridemia, whereas fat mass and homeostasis model assessment of insulin resistance were not. Leucine was the strongest determinant discriminating subjects with hypertriglyceridemia from those with normal triglyceride level (area under the curve, 0.822; 95% confidence interval, 0.740-0.903; P = .000001).

CONCLUSIONS

Serum leucine and isoleucine were associated with future serum triglyceride levels in girls during pubertal growth and predicted hypertriglyceridemia in early adulthood. Therefore, these amino acid indices may serve as biomarkers to identify individuals at high risk for developing hypertriglyceridemia and cardiovascular disease later in life. Further studies are needed to elucidate the role these amino acids play in the lipid metabolism.

Approved health claims for amino acids in/as food supplements

Food supplements in the European Union (EU) were initially regulated by Directive 2002/46/EC, whereas in 2006, EU adopted the new Regulation on nutrition and health claims made on food – Regulation 1924/2006. Meanwhile, in the United States of America (USA), dietary supplement is defined by the congress of Dietary Supplement Health and Education Act (DSHEA, 1994). Food supplements can be beneficial to the health of consumers, but scientific reviews of the existing data should be made by competent authorities. In Europe, a scientific review is made by European Food and Safety Authority (EFSA), the Panel of Dietetic Products, Nutrition and Allergies (NDA Panel). Amino-acids have been the object of many scientific studies, with many of them showing their implication in health. Amino-acids carry out a big role in many body functions, cells structure, transport and storage of nutrition, leading us to the main aim of this article that is providing data related to amino-acids implication in health benefits, specifically health claims of Arginine (Erection, vascular system, muscle integrity and hematopoesis immune system function, spermatogenesis), Glutamine (intestinal health, supporting glycogen replenishment, increasing cell swelling, immune health, abundance in the body, muscle function), Lysine (cardiovascular system, increase metabolism, bones, body tissue, immune system function). Nevertheless, they don`t take their credit yet and are not properly recognized in medical sciences in Europe, since the health claims of food containing amino-acids are still considered to be not established in terms of cause and effect relationship.

Effects of smoking and sun-drying on proximate, fatty and amino acids compositions of Southern pink shrimp (Penaeus notialis)

Traditional techniques of smoking and sun drying were investigated to understand their effects on nutritional qualities of Southern pink shrimp against present human dietary needs. Shrimps subjected to hot smoking at 71 °C and sun drying at ambient temperature of 31 °C treatments were compared to fresh samples. Proximate composition dry weight basis showed that smoked product were highest in protein and carbohydrate (P < 0.05) while fat was raised in sundried products (P < 0.05). The monounsaturated fatty acid (MUFAs) were highest ranging from 35.87 to 40.35 % in all products. Oleic acid (18:1) had highest value of 24.26 % in the smoked. Eicosapentanoic acid (C20:5 n-3) was highest in the sundried while Docosahexaenoic acid (C22:6 n-3) predominated in the fresh. The shrimp protein had Glutamate as the most abundant amino acid in the three forms. Both preservation methods significantly (P < 0.01) raised the values of tyrosine, histidine and leucine. The Ω-3/Ω-6 ratios showed that prawn is rich in omega 3. The highest arginine/lysine ratio (1.54) was obtained in sundried. The EAA/NEAA ratios ranged from 0.72 to 0.80 while index of atherogenicity (IA) and index of thrombogenicity (IT) ranged from 0.71 to 0.82 and 0.21 to 0.30 respectively in all forms. All products forms showed different advantages with respect to quality and nutrition, smoked samples however, offered the best benefits. Information provided is the first detailed study on the impacts of smoking and sun-drying on the nutritional qualities of a shrimp with tremendous economic and nutritional importance.

Protein and vegetarian diets

A vegetarian diet can easily meet human dietary protein requirements as long as energy needs are met and a variety of foods are eaten. Vegetarians should obtain protein from a variety of plant sources, including legumes, soy products, grains, nuts and seeds. Eggs and dairy products also provide protein for those following a lacto-ovo-vegetarian diet. There is no need to consciously combine different plant proteins at each meal as long as a variety of foods are eaten from day to day, because the human body maintains a pool of amino acids which can be used to complement dietary protein. The consumption of plant proteins rather than animal proteins by vegetarians may contribute to their reduced risk of chronic diseases such as diabetes and heart disease.

Efficacy and safety of a parenteral amino acid solution containing alanyl-glutamine versus standard solution in infants: a first-in-man randomized double-blind trial

BACKGROUND & AIMS

Efforts are directed at reaching the optimal composition of pediatric amino acids (AA) infusions. The goal was to demonstrate the safety and efficacy of a newly developed parenteral AA solution containing alanyl-glutamine (GLN-AA) compared to Standard-AA.

METHODS

This is a randomized (2:1), double-blind, multicentre clinical pilot trial. Infants after surgical interventions were allocated to receive GLN-AA or Standard-AA over a minimum of 5 days to maximum of 10 days. AA profiles in blood samples obtained at baseline, day 7, and end of treatment were compared to normal ranges. Data regarding safety, and efficacy were also collected.

RESULTS

Infants were comparable for (safety population) gestational age at birth (36 vs 38 weeks), birth weight (2460 vs 2955 g), and day of life during start intervention (1 vs 2 days). Plasma AA profiles in infants treated with GLN-AA (n = 13) were closer the normal ranges than those in infants treated with Standard-AA (n = 6). There were no clinical or statistical differences in adverse events, safety and efficacy parameters between both groups.

CONCLUSION

This first-in-man study shows that GLN-AA is safe in infants after surgical interventions, and is well tolerated. Compared to reference values, GLN-AA better reflects the amino acid requirements of the infant.

Validation of an in vitro digestive system for studying macronutrient decomposition in humans

The digestive process transforms nutrients and bioactive compounds contained in food to physiologically active compounds. In vitro digestion systems have proven to be powerful tools for understanding and monitoring the complex transformation processes that take place during digestion. Moreover, the investigation of the physiological effects of certain nutrients demands an in vitro digestive process that is close to human physiology. In this study, human digestion was simulated with a 3-step in vitro process that was validated in depth by choosing pasteurized milk as an example of a complex food matrix. The evolution and decomposition of the macronutrients was followed over the entire digestive process to the level of intestinal enterocyte action, using protein and peptide analysis by SDS-PAGE, reversed-phase HPLC, size exclusion HPLC, and liquid chromatography-MS. The mean peptide size after in vitro digestion of pasteurized milk was 5-6 amino acids (AA). Interestingly, mostly essential AA (93.6%) were released during in vitro milk digestion, a significantly different relative distribution compared to the total essential AA concentration of bovine milk (44.5%). All TG were degraded to FFA and monoacylglycerols. Herein, we present a human in vitro digestion model validated for its ability to degrade the macronutrients of dairy products comparable to physiological ranges. It is suited to be used in combination with a human intestinal cell culture system, allowing ex vivo bioavailability measurements and assessment of the bioactive properties of food components.

Exploring metabolic pathway reconstruction and genome-wide expression profiling in Lactobacillus reuteri to define functional probiotic features

The genomes of four Lactobacillus reuteri strains isolated from human breast milk and the gastrointestinal tract have been recently sequenced as part of the Human Microbiome Project. Preliminary genome comparisons suggested that these strains belong to two different clades, previously shown to differ with respect to antimicrobial production, biofilm formation, and immunomodulation. To explain possible mechanisms of survival in the host and probiosis, we completed a detailed genomic comparison of two breast milk–derived isolates representative of each group: an established probiotic strain (L. reuteri ATCC 55730) and a strain with promising probiotic features (L. reuteri ATCC PTA 6475). Transcriptomes of L. reuteri strains in different growth phases were monitored using strain-specific microarrays, and compared using a pan-metabolic model representing all known metabolic reactions present in these strains. Both strains contained candidate genes involved in the survival and persistence in the gut such as mucus-binding proteins and enzymes scavenging reactive oxygen species. A large operon predicted to encode the synthesis of an exopolysaccharide was identified in strain 55730. Both strains were predicted to produce health-promoting factors, including antimicrobial agents and vitamins (folate, vitamin B₁₂). Additionally, a complete pathway for thiamine biosynthesis was predicted in strain 55730 for the first time in this species. Candidate genes responsible for immunomodulatory properties of each strain were identified by transcriptomic comparisons. The production of bioactive metabolites by human-derived probiotics may be predicted using metabolic modeling and transcriptomics. Such strategies may facilitate selection and optimization of probiotics for health promotion, disease prevention and amelioration.

Establishment of reference range of plasma amino acids for younger Chinese children by reverse phase HPLC

BACKGROUND

Due to lack of country-specific norms in China, we established the reference range of plasma amino acids for younger Chinese children by reverse phase high-performance liquid chromatography (HPLC).

METHODS

Plasma proteins were precipitated with ethanol. L-Norvaline served as an internal standard. This HPLC method was based on automated precolumn derivatization using o-phthalaldehyde 3-mercaptopropionic acid for primary amino acids and 9-fluorenylmethyl chloroformate for secondary amino acids. Twenty-three amino acid derivatives were separated by a Zorbax Eclipse AAA column and detected fluorometrically. Plasma amino acids were measured in 108 healthy Chinese children (ages 0-5 years, 59 boys and 49 girls).

RESULTS

The assay was linear from 7.2 to 925.0 micromol/L for all amino acids. Recovery of amino acids added to plasma samples was 93%-107%. Within- and between-run reproducibility was 0.18%-6.27% and 2.94%-16.15%, respectively. Sex- and age-specific plasma amino acid reference range for younger Chinese children was established. In our study, the boys had significantly higher levels of glutamine, citrulline, and tryptophan than girls (p < 0.05), and the girls had a significantly higher level of alanine than boys (p < 0.05). Compared with the 0- to 1-year group, the 1- to 5-year group had significantly higher levels of citrulline, valine, phenylalanine, isoleucine, and sarcosine and lower levels of aspartate, glutamate, serine, threonine, alanine, methionine, and tryptophan (p < 0.05).

CONCLUSIONS

This study validates the HPLC method described here as a simple, rapid, and reliable assay. The reference range of plasma amino acids for younger Chinese children is different from that for Caucasian children and will facilitate our clinical diagnosis in the future.

Control of immune response by amino acid metabolism

The interaction between pathogenic microorganisms and their hosts is regulated by reciprocal survival strategies, including competition for essential nutrients. Though paradoxical, mammalian hosts have learned to take advantage of amino acid catabolism for controlling pathogen invasion and, at the same time, regulating their own immune responses. In this way, ancient catabolic enzymes have acquired novel functions and evolved into new structures with highly specialized functions, which go beyond the struggle for survival. In this review, we analyze the evidence supporting a critical role for the metabolism of various amino acids in regulating different steps of both innate and adaptive immunity.

Increased synthesis of α-tocopherol, paramylon and tyrosine by Euglena gracilis under conditions of high biomass production

AIMS

To analyse the production of different metabolites by dark-grown Euglena gracilis under conditions found to render high cell growth.

METHODS AND RESULTS

  The combination of glutamate (5 g l(-1) ), malate (2 g l(-1) ) and ethanol (10 ml l(-1) ) (GM + EtOH); glutamate (7·15 g l(-1) ) and ethanol (10 ml l(-1) ); or malate (8·16 g l(-1) ), glucose (10·6 g l(-1) ) and NH(4) Cl (1·8 g l(-1) ) as carbon and nitrogen sources, promoted an increase of 5·6, 3·7 and 2·6-fold, respectively, in biomass concentration in comparison with glutamate and malate (GM). In turn, the production of α-tocopherol after 120 h identified by LC-MS was 3·7 ± 0·2, 2·4 ± 0·1 and 2 ± 0·1 mg [g dry weight (DW)](-1) , respectively, while in the control medium (GM) it was 0·72 ± 0·1 mg (g DW)(-1) . For paramylon synthesis, the addition of EtOH or glucose induced a higher production. Amino acids were assayed by RP-HPLC; Tyr a tocopherol precursor and Ala an amino acid with antioxidant activity were the amino acids synthesized at higher concentration.

CONCLUSIONS

Dark-grown E. gracilis Z is a suitable source for the generation of the biotechnologically relevant metabolites tyrosine, α-tocopherol and paramylon.

SIGNIFICANCE AND IMPACT OF THE STUDY

By combining different carbon and nitrogen sources and inducing a tolerable stress to the cell by adding ethanol, it was possible to increase the production of biomass, paramylon, α-tocopherol and some amino acids. The concentrations of α-tocopherol achieved in this study are higher than others reported previously for Euglena, plant and algal systems. This work helps to understand the effect of different carbon sources on the synthesis of bio-molecules by E. gracilis and can be used as a basis for future works to improve the production of different metabolites of biotechnological importance by this organism.

Vibrational analysis of amino acids and short peptides in hydrated media. VI. Amino acids with positively charged side chains: L-lysine and L-arginine

In two recent reports of the same series (J. Phys. Chem. B 2007, 111, 1470-1477 and J. Phys. Chem. B 2009, 113, 3169-3178), we have described the geometrical and vibrational analysis of glycine and amino acids (AAs) with hydrophobic side chains through the joint use of optical spectroscopy and quantum mechanical calculations. Here, we report Raman scattering and Fourier-Transform Infrared (FT-IR) Attenuated Total Reflectance (ATR) spectra measured from the aqueous solutions (H(2)O and D(2)O) of L-lysine and L-arginine, i.e. two alpha-AAs with positively charged hydrophilic side chains. The discussion on the vibrational features of both AAs could be carried out thanks to the theoretical calculations performed by means of the Density Functional Theory (DFT) approach at the B3LYP/6-31++G* level. We have analyzed the influence of implicit (with a polarizable dielectric continuum) and explicit (by means of an H(2)O cluster interacting with H-donor and H-acceptor sites of AAs) hydration models. In addition, through the calculated geometrical parameters and vibrational wavenumbers, a discussion was performed on the effect of the Cl(-) anion interacting with the positively charged side chains of explicitly hydrated AAs.

Recent progress in deciphering the biosynthesis of aspartate-derived amino acids in plants

Plants are either directly or indirectly the source of most of the essential amino acids in animal diets. Four of these essential amino acids-methionine, threonine, isoleucine, and lysine-are all produced from aspartate via a well studied biosynthesis pathway. Given the nutritional interest in essential amino acids, the aspartate-derived amino acid pathway has been the subject of extensive research. Additionally, several pathway enzymes serve as targets for economically important herbicides, and some of the downstream products are biosynthetic precursors for other essential plant metabolites such as ethylene and S-adenosylmethionine. Recent and ongoing research on the aspartate-derived family of amino acids has identified new enzyme activities, regulatory mechanisms, and in vivo metabolic functions. Together, these discoveries will open up new possibilities for plant metabolic engineering.

Age-related changes of muscle and plasma amino acids in healthy children

The aim of the study was to explore if changes in muscle and plasma amino acid concentrations developed during growth and differed from levels seen in adults. The gradient and concentrations of free amino acids in muscle and plasma were investigated in relation to age in metabolic healthy children. Plasma and specimens from the abdominal muscle were obtained during elective surgery. The children were grouped into three groups (group 1: < 1 year, n = 8; group 2: 1-4 years, n = 13 and group 3: 5-15 years, n = 15). A reference group of healthy adults (21-38 years, n = 22) was included in their comparisons and reflected specific differences between children and adults. In muscle the concentrations of 8 out of 19 amino acids analysed increased with age, namely taurine, aspartate, threonine, alanine, valine, isoleucine, leucine, histidine, as well as the total sums of branched chain amino acids (BCAA), basic amino acids (BAA) and total sum of amino acids (P < 0.05). In plasma the concentrations of threonine, glutamine, valine, cysteine, methionine, leucine, lysine, tryptophane, arginine, BCAA, BAA and the essential amino acids correlated with age (P < 0.05). These results indicate that there is an age dependency of the amino acid pattern in skeletal muscle and plasma during growth.

C-reactive protein and interleukin-6 are decreased in transgenic sickle cell mice fed a high protein diet

Sickle cell disease is associated with hypermetabolism and a consequent shortage of substrates for normal growth and healthy immune response. The protein:energy ratio is a major determinant of dietary adequacy; the requirement for optimal growth of control mice is 20% of energy from dietary protein. This study investigated the efficacy of increased dietary protein for improving weight gain and reducing inflammation in the Berkeley sickle cell mouse model (S). The study examined the effect of diet on weight gain and circulating levels of 2 inflammatory proteins, C-reactive protein (CRP), and cytokine interleukin-6 (IL-6). Male C57BL/6 (C) control (n = 8) and S mice (n = 8) were randomized at weaning to 40 d of isoenergetic diets containing 20% (normal) and 35% (high) of energy from protein (C20, C35, S20, S35), replacing dextrin. Rate of weight gain was calculated and plasma CRP and IL-6 concentrations determined by ELISA. Liver mRNA expression of these proteins was measured by real-time PCR and L-arginase by colorimetric assay. S35 mice tended to gain weight more rapidly than S20 mice (P = 0.06) and more rapidly than C35 mice (P < 0.01). Circulating CRP and IL-6 levels were also lower in S35 mice than in S20 mice (P < 0.05), as was liver CRP mRNA expression (P < 0.01). These results demonstrate that introducing a high protein diet at weaning attenuates the steady-state inflammation in this S mouse model. Dietary L-arginine availability was investigated as a possible mechanism for increased nitric oxide production and consequent reduced inflammation.

Stress response and changes in amino acid requirements in Senegalese sole (Solea senegalensis Kaup 1858)

Fish in aquaculture are often exposed to various stressors that may change their ability to survive or limit growth. Amino acids are used for processes other than growth, including stress response. This study intended to analyse how repeated acute handling stress can affect growth and amino acid requirements in fish. Senegalese sole juveniles were weekly held in the air during 3 min (Handling) for 9 weeks; Control groups were left undisturbed. Growth and plasma levels of stress indicators and of free amino acids were assessed at the end of the experiment. Plasma cortisol and osmolality levels showed that fish in the Handling treatment were stressed, but growth was unaffected. Plasma amino acid concentrations indicate that their requirements in stressed fish were altered, which probably reflects the synthesis of proteins or other specific compounds related to stress response.

Nutrition for the critically ill child: enteral and parenteral support

The requirements of growth and organ development create a challenge in nutrition management for the pediatric patient. The stress of critical illness further complicates the delivery of adequate nutrients. Enteral feeding has several advantages over parenteral nutrition (PN), which include preservation of the gastrointestinal mucosa and decreasing the occurrence of sepsis related to bacterial translocation. Although feeding through the gastrointestinal tract is the preferred route for nutritional management, there are specific instances when PN as adjunctive or sole therapy is necessary to meet nutritional needs. With meticulous attention to fluid, caloric, protein, and fat requirements along with monitoring the metabolic status of the patient, it is possible to provide full nutritional support for the critically ill child within 24 to 48 hours of hospital admission.