Metabolism of cysteine is modified during the acute phase of sepsis in rats

The impact of glycine and glutamate, as components of glutathione precursors, on the productivity, digestive performance and blood profile of weaning pigs

The impact of glycine and glutamate, as components of glutathione (GSH) precursors, was studied as a factor in determining the growth rate of weaning pigs, their digestion of nutrient supplements and their blood concentration levels. There were 180 crossbred weaning pigs with an average body weight (BW) of 7.94 ± 1.53 kg (five pigs per pen [two barrows and three gilts]; nine pens per treatment) that were randomly assigned to one of four diets. We used a basal diet as the control, TRT1 as the treatment with 0.10% precursor of GSH, TRT2 as the treatment with 0.20% precursor of GSH and TRT3 as the treatment with 0.30% precursor of GSH. The BW of weaning pigs exhibited a linear increase on days 7 (p < 0.001), 21 (p < 0.001) and 42 (p < 0.009) following the supplementation with the GSH precursor. Supplementation with GSH precursor led to a consistent and gradual increase in average daily gain (ADG) on days 8-21, 22-42 and overall, as indicated by a significant linear trend (p < 0.05). G: F was linearly increased (p < 0.05) on days 22-42 and overall with the increment in the precursor of GSH supplementation. However, GSH precursor supplementation did not have any impact on nutrient digestibility and blood profile in the treatment group. In summary, the administration of GSH precursor improved BW, ADG and G: F ratio while not affecting nutrient digestibility or blood profile.

Identifying hepatic genes regulating the ovine response to gastrointestinal nematodes using RNA-Sequencing

Gastrointestinal nematode (GIN) infections are considered the most important disease of grazing sheep and due to increasing anthelmintic resistance, chemical control alone is inadequate. Resistance to Gastrointestinal nematode infection is a heritable trait, and through natural selection many sheep breeds have higher resistance. Studying the transcriptome from GIN-exposed and GIN-unexposed sheep using RNA-Sequencing technology can provide measurements of transcript levels associated with the host response to Gastrointestinal nematode infection, and these transcripts may harbor genetic markers that can be used in selective breeding programs to enhance disease resistance. The objective of this study was to compare liver transcriptomes of sheep naturally exposed to Gastrointestinal nematode s, with either high or low parasite burdens, to GIN-unexposed control sheep in order to identify key regulator genes and biological processes associated with Gastrointestinal nematode infection. Differential gene expression analysis revealed no significant differentially expressed genes (DEG) between sheep with a high or low parasite burden (p-value ≤0.01; False Discovery Rate (FDR) ≤ 0.05; and Fold-Change (FC) of > ±2). However, when compared to the control group, low parasite burden sheep showed 146 differentially expressed genes (64 upregulated and 82 downregulated in the low parasite burden group relative to the control), and high parasite burden sheep showed 159 differentially expressed genes (57 upregulated and 102 downregulated in the low parasite burden group relative to the control) (p-value ≤0.01; FDR ≤0.05; and FC of > ±2). Among these two lists of significant differentially expressed genes, 86 differentially expressed genes (34 upregulated, 52 downregulated in the parasited group relative to the control) were found in common between the two parasite burden groups compared to the control (GIN-unexposed sheep). Functional analysis of these significant 86 differentially expressed genes found upregulated genes involved in immune response and downregulated genes involved in lipid metabolism. Results of this study offer insight into the liver transcriptome during natural Gastrointestinal nematode exposure that helps provide a better understanding of the key regulator genes involved in Gastrointestinal nematode infection in sheep.

Activation of the eIF2α-ATF4 Pathway by Chronic Paracetamol Treatment Is Prevented by Dietary Supplementation with Cysteine

Chronic treatment with acetaminophen (APAP) induces cysteine (Cys) and glutathione (GSH) deficiency which leads to adverse metabolic effects including muscle atrophy. Mammalian cells respond to essential amino acid deprivation through the phosphorylation of the eukaryotic translation initiation factor 2α (eIF2α). Phosphorylated eIF2α leads to the recruitment of activating transcription factor 4 (ATF4) to specific CCAAT/enhancer-binding protein-ATF response element (CARE) located in the promoters of target genes. Our purpose was to study the activation of the eIF2α-ATF4 pathway in response to APAP-induced Cys deficiency, as well as the potential contribution of the eIF2α kinase GCN2 and the effect of dietary supplementation with Cys. Our results showed that chronic treatment with APAP activated both GCN2 and PERK eIF2α kinases and downstream target genes in the liver. Activation of the eIF2α-ATF4 pathway in skeletal muscle was accompanied by muscle atrophy even in the absence of GCN2. The dietary supplementation with cysteine reversed APAP-induced decreases in plasma-free Cys, liver GSH, muscle mass, and muscle GSH. Our new findings demonstrate that dietary Cys supplementation also reversed the APAP-induced activation of GCN2 and PERK and downstream ATF4-target genes in the liver.

Alteration of the dietary methionine:cysteine ratio modulates the inflammatory response to an inter-peritoneal injection of lipopolysaccharide in Wistar rats

Sulphur amino acids (SAA) are essential for multiple physiological/metabolic processes, with the ratio of dietary methionine:cysteine (Met:Cys) being an important contributor to pro-inflammatory responses, including TNF-α activity. The current study was designed to determine the effect an altered dietary SAA ratio, and the resulting reliance on the transsulfuration pathway to supply Cys, will have on the inflammatory response. In the present study, 100 µg/kg of an intraperitoneal (IP) injection of lipopolysaccharide (LPS) was used as a model for systemic inflammation. Male Wistar rats were randomized to one of two amino acid-defined diets, (100Met:0Cys or 50Met:50Cys) and subdivided to receive either IP LPS or saline injections. LPS significantly increased total plasma Cys, homocysteine (Hcy) and glutathione (GSH) 240 min post-IP injection in rats fed a 50Met:50Cys ratio compared to other treatments. The TNF-α area under the curve for LPS-treated rats consuming a dietary 50Met:50Cys ratio was significantly higher (p< 0.004) compared to those consuming a dietary 100Met:0Cys ratio. A significant increase in the percentage of leukocytes that were neutrophils was observed in rats injected with LPS when compared to saline with no effect of diet. These results demonstrate that an alteration of the dietary Met:Cys ratio did not attenuate the inflammatory response to an IP injection of LPS in Wistar rats; however, a diet with a balanced Met:Cys ratio increased concentrations of Cys and GSH which may result in a more rapid response to an LPS challenge.

Amino Acids in Intestinal Physiology and Health

Dietary protein digestion is an efficient process resulting in the absorption of amino acids by epithelial cells, mainly in the jejunum. Some amino acids are extensively metabolized in enterocytes supporting their high energy demand and/or production of bioactive metabolites such as glutathione or nitric oxide. In contrast, other amino acids are mainly used as building blocks for the intense protein synthesis associated with the rapid epithelium renewal and mucin production. Several amino acids have been shown to support the intestinal barrier function and the intestinal endocrine function. In addition, amino acids are metabolized by the gut microbiota that use them for their own protein synthesis and in catabolic pathways releasing in the intestinal lumen numerous metabolites such as ammonia, hydrogen sulfide, branched-chain amino acids, polyamines, phenolic and indolic compounds. Some of them (e.g. hydrogen sulfide) disrupts epithelial energy metabolism and may participate in mucosal inflammation when present in excess, while others (e.g. indole derivatives) prevent gut barrier dysfunction or regulate enteroendocrine functions. Lastly, some recent data suggest that dietary amino acids might regulate the composition of the gut microbiota, but the relevance for the intestinal health remains to be determined. In summary, amino acid utilization by epithelial cells or by intestinal bacteria appears to play a pivotal regulator role for intestinal homeostasis. Thus, adequate dietary supply of amino acids represents a key determinant of gut health and functions.

Immune system stimulation increases the irreversible loss of cysteine to taurine, but not sulfate, in starter pigs

An isotope tracer study was conducted to evaluate the effects of immune system stimulation (ISS) on the irreversible loss of cysteine (Cys) to taurine (Tau) and sulfate (SO4), as well as glutathione (GSH) synthesis, during the fed state in pigs. We previously have reported that ISS increases plasma Cys flux and the GSH synthesis rate at the tissue and whole-body levels in growing pigs. Thus, the current article presents the data on the irreversible loss of Cys during ISS in pigs. Ten gilts (BW: 7.0 ± 0.12 kg) were feed restricted a sulfur amino acids (SAA) limiting diet and injected twice with either saline (n = 4) or increasing amounts of E. coli lipopolysaccharide (n = 6). The day after the second injection, a 5-h primed continuous intravenous infusion of 35S-Cys was conducted. ISS reduced plasma Cys and total SAA concentrations (16% and 21%, respectively; P < 0.05). However, ISS had no effect on the plasma concentrations of Tau and SO4, nor did it affect the appearance of 35S in plasma Tau, plasma SO4, urinary Tau, or urinary SO4 (P > 0.19). On a whole-body basis and including urinary excretion, ISS increased the appearance of 35S in Tau by 67% (P < 0.05), but tended to decrease the appearance of 35S in SO4 by 22% (P < 0.09). Overall, the current findings indicate that during ISS, decreased plasma SAA concentrations and increased plasma Cys flux are attributed in part to increased rates of Cys conversion to Tau, but not Cys catabolism to SO4. Thus, increased utilization of Cys for the synthesis of immune system metabolites, such as GSH and Tau, is likely the main contributor to increased Cys flux during ISS in pigs. In addition, the irreversible loss of Cys during ISS is small and has a minimal impact on the daily SAA requirements of starter pigs.

Immune system stimulation increases the plasma cysteine flux and whole-body glutathione synthesis rate in starter pigs1

Glutathione (GSH) is the major intracellular thiol that plays a role in numerous detoxification, bio-reduction, and conjugation reactions. The availability of Cys is thought to be the rate-limiting factor for the synthesis of GSH. The effects of immune system stimulation (ISS) on GSH levels and the GSH synthesis rate in various tissues, as well as the plasma flux of Cys, were measured in starter pigs fed a sulfur AA (SAA; Met + Cys) limiting diet. Ten feed-restricted gilts with initial body weight (BW) of 7.0 ± 0.12 kg were injected i.m. twice at 48-h intervals with either sterile saline (n = 4; ISS-) or increasing amounts of Escherichia coli lipopolysaccharide (n = 6; ISS+). The day after the second injection, pigs received a primed constant infusion of 35S-Cys (9,300 kBq/pig/h) for 5 h via a jugular catheter. Blood and tissue free Cys and reduced GSH were isolated and quantified as the monobromobimane derivatives by HPLC. The rate of GSH synthesis was determined by measurement of the specific radioactivity of GSH and tissue free Cys at the end of the infusion period. Plasma Cys and total SAA levels were reduced (16% and 21%, respectively), but plasma Cys flux was increased (26%) by ISS (P < 0.05). Immune system stimulation increased GSH levels in the plasma (48%; P < 0.05), but had no effect on GSH levels in the liver, small and large intestines, heart, muscle, spleen, kidney, lung, and erythrocytes. The fractional synthesis rate (FSR) of GSH was higher (P < 0.05) in the liver (34%), small intestine (78%), large intestine (72%), heart (129%), muscle (37%), and erythrocytes (47%) of ISS+ pigs compared to ISS- pigs. The FSR of GSH tended (P = 0.08) to be higher in the lungs (45%) of ISS+ pigs than in ISS- pigs. The absolute rate of GSH synthesis was increased by ISS (mmol/kg wet tissue/d ± SE, ISS- vs. ISS+; P < 0.05) in the liver (5.22 ± 0.22 vs. 7.20 ± 0.59), small intestine (2.54 ± 0.25 vs. 4.52 ± 0.56), large intestine (0.61 ± 0.06 vs. 1.06 ± 0.16), heart (0.21 ± 0.03 vs. 0.48 ± 0.08), lungs (1.50 ± 0.10 vs. 2.90 ± 0.21), and muscle (0.21 ± 0.03 vs. 0.34 ± 0.04), but it remained unchanged in erythrocytes, the kidney, and the spleen (P > 0.80). The current findings suggest that GSH synthesis is increased during ISS, contributing to enhanced maintenance sulfur amino acid requirements in starter pigs during ISS.

Plasma Transthyretin as A Biomarker of Sarcopenia in Elderly Subjects

Skeletal muscle (SM) mass, the chief component of the structural compartment belonging to lean body mass (LBM), undergoes sarcopenia with increasing age. Decreased SM in elderly persons is a naturally occurring process that may be accelerated by acute or chronic nutritional deficiencies and/or inflammatory disorders, declining processes associated with harmful complications. A recently published position paper by European experts has provided an overall survey on the definition and diagnosis of sarcopenia in elderly persons. The present review describes the additional contributory role played by the noninvasive transthyretin (TTR) micromethod. The body mass index (BMI) formula is currently used in clinical studies as a criterion of good health to detect, prevent, and follow up on the downward trend of muscle mass. The recent upsurge of sarcopenic obesity with its multiple subclasses has led to a confused stratification of SM and fat stores, prompting workers to eliminate BMI from screening programs. As a result, investigators are now focusing on indices of protein status that participate in SM growth, maturation, and catabolism that might serve to identify sarcopenia trajectories. Plasma TTR is clearly superior to all other hepatic biomarkers, showing the same evolutionary patterns as those displayed in health and disease by both visceral and structural LBM compartments. As a result, this TTR parameter maintains positive correlations with muscle mass downsizing in elderly persons. The liver synthesis of TTR is downregulated in protein-depleted states and suppressed in cytokine-induced inflammatory disorders. TTR integrates the centrally-mediated regulatory mechanisms governing the balance between protein accretion and protein breakdown, emerging as the ultimate indicator of LBM resources. This review proposes the adoption of a gray zone defined by cut-off values ranging from 200 mg/L to 100 mg/L between which TTR plasma values may fluctuate and predict either the best or the worst outcome. The best outcome occurs when appropriate dietary, medicinal and surgical decisions are undertaken, resuming TTR synthesis which manifests rising trends towards pre-stress levels. The worst occurs when all therapeutic means fail to succeed, leading inevitably to complete exhaustion of LBM and SM metabolic resources with an ensuing fatal outcome. Some patients may remain unresponsive in the middle of the gray area, combining steady clinical states with persistent stagnant TTR values. Using the serial measurement of plasma TTR values, these last patients should be treated with the most aggressive and appropriate therapeutic strategies to ensure the best outcome.

N-acetylcysteine prevents glutathione decrease and does not interfere with paracetamol antinociceptive effect at therapeutic dosage: a randomized double-blind controlled trial in healthy subjects

Paracetamol (APAP) may lead to hepatic changes even at therapeutic dosages. Glutathione (GSH) plays a pivotal role in APAP metabolism as it allows the detoxification of a toxic metabolite. N-Acetylcysteine (NAC) is APAP antidote, is also largely used as a mucoactive drug and is often associated with APAP. This study aims at evaluating if 1- NAC modifies APAP pain efficacy and 2- NAC prevents glutathione depletion with APAP at therapeutic doses. This double-blind randomized controlled study (NCT02206178) was carried out in 24 healthy volunteers. APAP was given for 4 days (1 g ×4 daily) with NAC or with placebo. Thermal pain tests, whole blood GSH, and hepatic enzymes (ASAT, ALAT) were measured before (D0) and after (D4) oral APAP-NAC or APAP-placebo intake. anova for repeated measures adapted to cross-overdesign was performed and a two-tailed type I error was fixed at 5%. The primary endpoint was the area under the curve (0-240 min) of pain intensity (Numerical Scale) after thermal pain stimulation using Pathway-Medoc^® . APAP antinociceptive effect was similar in both groups. GSH was maintained to its baseline value in the APAP/NAC group but diminished in the APAP/placebo group (P = 0.033). This study shows for the first time that APAP antinociceptive effectiveness is not influenced by NAC. It also shows that the effect of APAP at therapeutic dosage on GSH may be counteracted by NAC. These issues are particularly important for patients as APAP is often prescribed for years as a first-line pain treatment and further trials in patients are now warranted.

Dietary supplementation with cysteine prevents adverse metabolic outcomes of repeated cures with paracetamol in old rats

Cysteine (Cys), a conditionally indispensable amino acid, is required for the detoxification of paracetamol (acetaminophen, N-acetyl-para-aminophenol, 4-hydroxy-acetanilide, APAP), a drug of widespread use in older persons. We recently reported that repeated APAP cures could worsen sarcopenia in old rats, likely to be due to the impairment of Cys/GSH homoeostasis. The aim of the study was to evaluate whether a dietary Cys supplementation during APAP cures could improve Cys/GSH homoeostasis and thus preserve skeletal muscle. Male 21·5-month-old Wistar rats received three 2-week-long cures of APAP (1 % of diet) alone or with extra Cys (0·5 % of diet), intercalated with washout periods of 2 weeks (APAP and APAP-Cys groups, respectively). They were compared with untreated control rats (CT group). CT and APAP-Cys groups were pair-fed to the APAP group. Dietary Cys supplementation was efficient to prevent increase in liver mass (P<0·0001), decrease in liver GSH (P<0·0001), increase in blood GSH concentration (P<0·0001), and to some extent, decrease in plasma free Cys concentration (P<0·05), all induced by repeated APAP cures. The addition of Cys to APAP cures decreased plasma alanine transaminase (P<0·05), the fractional synthesis rate of liver proteins (P<0·01), and increased masses of extensor digitorum longus (P<0·01), and soleus (P<0·05), compared with the APAP group. Cys supplementation prevented alteration in Cys/GSH homoeostasis and increased some muscle masses in old rats under repeated cures with a non-toxic dose of APAP.

Long-term dietary supplementation with cystathionine improves tissue glutathione in ageing rats

BACKGROUND

Ageing is associated with decrease in tissue glutathione that can be reduced by food fortification with the amino acid cysteine. However, cysteine is not stable in solution and generates bad taste. Cystathionine, the direct precursor of cysteine, could be a valuable alternative.

AIMS

This study aimed to determine whether long-term dietary supplementation with cystathionine induces an increase in glutathione pools.

METHODS

Aged rats (20.5-month-old) were fed ad libitum during 29 weeks with either a cystathionine-supplemented diet (7.3 g/kg, n = 90 rats) or a control iso-nitrogenous alanine-supplemented diet (2.9 g/kg, n = 90 rats).

RESULTS

Cystathionine was detected in the plasma of the cystathionine-supplemented rats but not in the control alanine-supplemented rats. Cystathionine increased glutathione concentrations in liver, small intestine and gastrocnemius muscle (P < 0.03). No adverse effect was observed.

CONCLUSION

Cystathionine supplementation being able to increase moderately glutathione in healthy old rats could be considered as a candidate for nutritional supports aiming to revert the stronger glutathione depletions occurring in unhealthy elderly.

Influence of dietary taurine and housing density on oviduct function in laying hens

Experiments were conducted to study the effects of dietary taurine and housing density on oviduct function in laying hens. Green-shell laying hens were randomly assigned to a free range group and two caged groups, one with low-density and the other with high-density housing. Each group was further divided into control (C) and taurine treatment (T) groups. All hens were fed the same basic diet except that the T groups' diet was supplemented with 0.1% taurine. The experiment lasted 15 d. Survival rates, laying rates, daily feed consumption, and daily weight gain were recorded. Histological changes, inflammatory mediator levels, and oxidation and anti-oxidation levels were determined. The results show that dietary taurine supplementation and reduced housing density significantly attenuated pathophysiological changes in the oviduct. Nuclear factor-κB (NF-κB) DNA binding activity increased significantly in the high-density housing group compared with the two other housing groups and was reduced by taurine supplementation. Tumor necrosis factor-α (TNF-α) mRNA expression in the high-density and low-density C and T groups increased significantly. In the free range and low-density groups, dietary taurine significantly reduced the expression of TNF-α mRNA. Supplementation with taurine decreased interferon-γ (IFN-γ) mRNA expression significantly in the low-density groups. Interleukin 4 (IL-4) mRNA expression was significantly higher in caged hens. IL-10 mRNA expression was higher in the high-density C group than in the free range and low-density C groups. Supplementation with taurine decreased IL-10 mRNA expression significantly in the high-density group and increased superoxide dismutase (SOD) activity in the free range hens. We conclude that taurine has important protective effects against oviduct damage. Reducing housing density also results in less oxidative stress, less inflammatory cell infiltration, and lower levels of inflammatory mediators in the oviduct. Therefore, both dietary taurine and reduced housing density can ameliorate oviduct injury, enhance oviduct health, and promote egg production in laying hens.

Polymorphisms of cystathionine beta-synthase gene are associated with susceptibility to sepsis

Sepsis is the systemic inflammatory host response to infection. Cystathionine beta-synthase (CBS)-dependent homocysteine (Hcy) pathway was demonstrated to affect disease severity and mortality in patients with severe sepsis/septic shock. Independent studies identified a single-nucleotide polymorphism (SNP, rs6586282, hg19 chr21:g.44478497C>T) in intron 14 of the CBS-coding gene (CBS) associated with Hcy plasma levels. We aimed to describe the association of this SNP and variants of a splice donor-affecting variable-number tandem repeat (VNTR, NG_008938.1:g.22763_22793[16_22]) 243 bp downstream of rs6586282 with severe human sepsis. We analyzed the VNTR structure and genotyped variants of rs6586282 and a neighboring SNP (rs34758144, hg19 chr21:g.44478582G>A) in two case-control studies including patients with severe sepsis/septic shock from Germany (n=168) and Greece (n=237). In both studies, we consistently observed an association of CBS VNTR alleles with sepsis susceptibility. Risk linearly increased with number of tandem repeats (per allele odds ratio in the adjusted analysis 1.34; 95% confidence interval (CI)=1.17-1.55; P<0.001). Association had also been shown for rs34758144 whose risk allele is in linkage disequilibrium with one long VNTR allele (19 repeat). In contrast, we observed no evidence for an effect on 28-day survival in patients with severe sepsis/septic shock (per allele hazard ratio in the adjusted analysis for VNTR 1.10; 95% CI=0.95-1.28; P=0.20). In a minigene approach, we demonstrated alternative splicing in distinct VNTR alleles, which, however, was independent of the number of tandem units. In conclusion, there is no ordinary conjunction between human CBS and severe sepsis/septic shock, but CBS genotypes are involved in disease susceptibility.

Clinical Potential of Hyperbaric Pressure-Treated Whey Protein

Whey protein (WP) from cow's milk is a rich source of essential and branched chain amino acids. Whey protein isolates (WPI) has been demonstrated to support muscle accretion, antioxidant activity, and immune modulation. However, whey is not readily digestible due to its tight conformational structure. Treatment of WPI with hyperbaric pressure results in protein unfolding. This enhances protein digestion, and results in an altered spectrum of released peptides, and greater release of essential and branched chain amino acids. Pressurized whey protein isolates (pWPI), through a series of cell culture, animal models and clinical studies, have been demonstrated to enhance muscle accretion, reduce inflammation, improve immunity, and decrease fatigue. It is also conceivable that pWPI would be more accessible to digestive enzymes, which would allow for a more rapid proteolysis of the proteins and an increased or altered release of small bioactive peptides. The altered profile of peptides released from WP digestion could thus play a role in the modulation of the immune response and tissue glutathione (GSH) concentrations. The research to date presents potentially interesting applications for the development of new functional foods based on hyperbaric treatment of WPI to produce products with more potent nutritional and nutraceutical properties.

Chronic Intake of Sucrose Accelerates Sarcopenia in Older Male Rats through Alterations in Insulin Sensitivity and Muscle Protein Synthesis

BACKGROUND

Today, high chronic intake of added sugars is frequent, which leads to inflammation, oxidative stress, and insulin resistance. These 3 factors could reduce meal-induced stimulation of muscle protein synthesis and thus aggravate the age-related loss of muscle mass (sarcopenia).

OBJECTIVES

Our aims were to determine if added sugars could accelerate sarcopenia and to assess the capacity of antioxidants and anti-inflammatory agents to prevent this.

METHODS

For 5 mo, 16-mo-old male rats were starch fed (13% sucrose and 49% wheat starch diet) or sucrose fed (62% sucrose and 0% wheat starch diet) with or without rutin (5 g/kg diet), vitamin E (4 times), vitamin A (2 times), vitamin D (5 times), selenium (10 times), and zinc (+44%) (R) supplementation. We measured the evolution of body composition and inflammation, plasma insulin-like growth factor 1 (IGF-I) concentration and total antioxidant status, insulin sensitivity (oral-glucose-tolerance test), muscle weight, superoxide dismutase activity, glutathione concentration, and in vivo protein synthesis rates.

RESULTS

Sucrose-fed rats lost significantly more lean body mass (-8.1% vs. -5.4%, respectively) and retained more fat mass (+0.2% vs. -33%, respectively) than starch-fed rats. Final muscle mass was 11% higher in starch-fed rats than in sucrose-fed rats. Sucrose had little effect on inflammation, oxidative stress, and plasma IGF-I concentration but reduced the insulin sensitivity index (divided by 2). Meal-induced stimulation of muscle protein synthesis was significantly lower in sucrose-fed rats (+7.3%) than in starch-fed rats (+22%). R supplementation slightly but significantly reduced oxidative stress and increased muscle protein concentration (+4%) but did not restore postprandial stimulation of muscle protein synthesis.

CONCLUSIONS

High chronic sucrose intake accelerates sarcopenia in older male rats through an alteration of postprandial stimulation of muscle protein synthesis. This effect could be explained by a decrease of insulin sensitivity rather than by changes in plasma IGF-I, inflammation, and/or oxidative stress.

Dynamic changes in amino acid concentration profiles in patients with sepsis

Objectives

The goal of this work was to explore the dynamic concentration profiles of 42 amino acids and the significance of these profiles in relation to sepsis, with the aim of providing guidance for clinical therapies.

Methods

Thirty-five critically ill patients with sepsis were included. These patients were further divided into sepsis (12 cases) and severe sepsis (23 cases) groups or survivor (20 cases) and non-survivor (15 cases) groups. Serum samples from the patients were collected on days 1, 3, 5, 7, 10, and 14 following intensive care unit (ICU) admission, and the serum concentrations of 42 amino acids were measured.

Results

The metabolic spectrum of the amino acids changed dramatically in patients with sepsis. As the disease progressed further or with poor prognosis, the levels of the different amino acids gradually increased, decreased, or fluctuated over time. The concentrations of sulfur-containing amino acids (SAAs), especially taurine, decreased significantly as the severity of sepsis worsened or with poor prognosis of the patient. The serum concentrations of SAAs, especially taurine, exhibited weak negative correlations with the Sequential Organ Failure Assessment (SOFA) (r=-0.319) and Acute Physiology and Chronic Health Evaluation (APACHE) II (r=-0.325) scores. The areas under the receiver operating characteristic curves of cystine, taurine, and SAA levels and the SOFA and APACHE II scores, which denoted disease prognosis, were 0.623, 0.674, 0.678, 0.86, and 0.857, respectively.

Conclusions

Critically ill patients with disorders of amino acid metabolism, especially of SAAs such as cystine and taurine, may provide an indicator of the need for the nutritional support of sepsis in the clinic.

Trial Registration

ClinicalTrial.gov identifier NCT01818830.

High whey protein intake delayed the loss of lean body mass in healthy old rats, whereas protein type and polyphenol/antioxidant supplementation had no effects

Our aim was to compare and combine 3 nutritional strategies to slow down the age-related loss of muscle mass in healthy old rats: 1) increase protein intake, which is likely to stimulate muscle protein anabolism; 2) use leucine rich, rapidly digested whey proteins as protein source (whey proteins are recognized as the most effective proteins to stimulate muscle protein anabolism). 3) Supplement animals with a mixture of chamomile extract, vitamin E, vitamin D (reducing inflammation and oxidative stress is also effective to improve muscle anabolism). Such comparisons and combinations were never tested before. Nutritional groups were: casein 12% protein, whey 12% protein, whey 18% protein and each of these groups were supplemented or not with polyphenols/antioxidants. During 6 months, we followed changes of weight, food intake, inflammation (plasma fibrinogen and alpha-2-macroglobulin) and body composition (DXA). After 6 months, we measured muscle mass, in vivo and ex-vivo fed and post-absorptive muscle protein synthesis, ex-vivo muscle proteolysis, and oxidative stress parameters (liver and muscle glutathione, SOD and total antioxidant activities, muscle carbonyls and TBARS). We showed that although micronutrient supplementation reduced inflammation and oxidative stress, the only factor that significantly reduced the loss of lean body mass was the increase in whey protein intake, with no detectable effect on muscle protein synthesis, and a tendency to reduce muscle proteolysis. We conclude that in healthy rats, increasing protein intake is an effective way to delay sarcopenia.

A dietary supplementation with leucine and antioxidants is capable to accelerate muscle mass recovery after immobilization in adult rats

Prolonged inactivity induces muscle loss due to an activation of proteolysis and decreased protein synthesis; the latter is also involved in the recovery of muscle mass. The aim of the present work was to explore the evolution of muscle mass and protein metabolism during immobilization and recovery and assess the effect of a nutritional strategy for counteracting muscle loss and facilitating recovery. Adult rats (6–8 months) were subjected to unilateral hindlimb casting for 8 days (I0–I8) and then permitted to recover for 10 to 40 days (R10–R40). They were fed a Control or Experimental diet supplemented with antioxidants/polyphenols (AOX) (I0 to I8), AOX and leucine (AOX + LEU) (I8 to R15) and LEU alone (R15 to R40). Muscle mass, absolute protein synthesis rate and proteasome activities were measured in gastrocnemius muscle in casted and non-casted legs in post prandial (PP) and post absorptive (PA) states at each time point. Immobilized gastrocnemius protein content was similarly reduced (-37%) in both diets compared to the non-casted leg. Muscle mass recovery was accelerated by the AOX and LEU supplementation (+6% AOX+LEU vs. Control, P<0.05 at R40) due to a higher protein synthesis both in PA and PP states (+23% and 31% respectively, Experimental vs. Control diets, P<0.05, R40) without difference in trypsin- and chymotrypsin-like activities between diets. Thus, this nutritional supplementation accelerated the recovery of muscle mass via a stimulation of protein synthesis throughout the entire day (in the PP and PA states) and could be a promising strategy to be tested during recovery from bed rest in humans.

Burn injury differentially alters whole-blood and organ glutathione synthesis rates: An experimental model

Previous studies from our laboratories revealed a reduced rate of whole-blood (WB) glutathione (GSH) synthesis in severely burned patients. To determine whether WB GSH metabolism is an indicator of the status of GSH metabolism in one or more of the major organs, we used a burn rabbit model to determine GSH concentrations and rates of synthesis in WB, liver, lungs, kidney, and skeletal muscle. L-[1-¹³C]-cysteine was infused intravenously for 6 h in rabbits at 3 days post-burn and in sham burn controls. WB and organ ¹³C-enrichment of cysteine and GSH was determined by gas chromatography/mass spectrometry. Plasma cysteine metabolic flux was increased significantly (P < 0.01) following burn injury. WB, liver, and lung GSH concentrations (P = 0.054, P < 0.05, and P < 0.05, respectively) and fractional rates of GSH synthesis (P < 0.05, P < 0.01, and P < 0.05, respectively) were reduced at 3 days post-burn. Kidney was unaffected. There also appears to be an increased rate of GSH transport out of the liver after burn injury. Hence, there is a differential impact of burn injury on tissue and organ GSH status, with WB qualitatively reflecting the changes in lung and liver. It will be important to determine whether these changes are due to alterations in the intrinsic capacity for GSH synthesis and/or availability of amino acid precursors of GSH.

Immune system stimulation increases the optimal dietary methionine to methionine plus cysteine ratio in growing pigs

Chronic subclinical levels of disease occur frequently in intensive swine production and compromise nutrient use efficiency. Feeding additional Met plus Cys (M+C) has been implicated in improving the response of the animal to immune system stimulation (ISS) because they can serve as substrates for generating compounds involved in the immune response, such as glutathione and acute phase proteins. A N-balance study was conducted to assess the optimal dietary Met to Met plus Cys ratio (M:M+C) during ISS in 20-kg pigs. Thirty-six pigs were fed 800 g/d of 1 of 5 M+C-limiting diets, containing graded levels of M:M+C (0.42, 0.47, 0.52, 0.57, and 0.62) and supplying 2.5 g/d of M+C. After adaptation, N balances were determined sequentially during a 5-d prechallenge period and 2 ISS periods of 3 and 4 d, respectively. To induce ISS, pigs were injected intramuscularly with repeated and increasing doses of Escherichia coli lipopolysaccharide. Eye temperature and blood profile confirmed effective ISS. During ISS period 1, ISS reduced the mean N balance more severely than ISS period 2 (8.7 ± 0.3 vs. 9.6 ± 0.4 g/d; P < 0.001) and was less than the prechallenge period (10.0 ± 0.2 g/d; P < 0.001). An interactive effect of ISS and diet on N balance was observed (P < 0.001). Based on quadratic-plateau regression analysis, the optimal dietary M:M+C was 0.57 ± 0.03 and 0.59 ± 0.02 for the prechallenge period and ISS period 2, respectively. The optimal dietary M:M+C for ISS period 1 was found to be greater than 0.62, indicating that the optimal M:M+C is greater during ISS. It is suggested that this is the result of preferential use of Met during ISS. In conclusion, ISS results in an increase in the optimal dietary M:M+C in growing pigs.

Impact of immune system stimulation on the ileal nutrient digestibility and utilisation of methionine plus cysteine intake for whole-body protein deposition in growing pigs

The impact of immune system stimulation (ISS) on the ileal nutrient digestibility and utilisation of dietary methionine plus cysteine (SAA) intake for whole-body protein deposition (PD) was evaluated in growing pigs. For this purpose, sixty barrows were used in two experiments: thirty-six pigs in Expt I and twenty-four pigs in Expt II. Pigs were feed restricted and assigned to five levels of dietary SAA allowance (three and two levels in Expt I and II, respectively) from SAA-limiting diets. Following adaptation, pigs at each dietary SAA level were injected with either increasing amounts of Escherichia coli lipopolysaccharide (ISS+; eight and six pigs per dietary SAA level in Expt I and II, respectively) or saline (ISS - ; four and six pigs in Expt I and II, respectively) while measuring the whole-body nitrogen (N) balance. After N-balance observations, pigs were euthanised, organs were removed and ileal digesta were collected for determining nutrient digestibility. Ileal digestibility of gross energy, crude protein and amino acids was not affected by ISS (P>0·20). ISS reduced PD at all levels of dietary SAA intake (P< 0·01). The linear relationship between daily dietary SAA intake and PD observed at the three lowest dietary SAA intake levels indicated that ISS increased extrapolated maintenance SAA requirements (P< 0·05), but had no effect on the partial efficiency of the utilisation of dietary SAA intake for PD (P>0·20). Physiological and metabolic changes associated with systemic ISS had no effect on the ileal digestibility of nutrients per se, but altered SAA requirements for PD in growing pigs.

Food restriction and refeeding in lambs influence muscle antioxidant status

Compensatory growth, a frequent phenomenon observed in ruminants due to seasonal variation in food availability, affects protein metabolism including protein oxidation. These oxidation processes may have an impact on animal health as well as on meat protein degradation during post mortem aging (ie meat maturation). Sixteen male lambs were randomly divided into four groups. One group was fed ad libitum (C) and one group was food-restricted to 60% of the intake of the C group (R). The last two groups were restricted similarly to the R group and refed either ad libitum (RAL) or similarly to the C group (pair-feeding) (RPF). Muscles samples were taken immediately after slaughter. The present study showed that the restriction/refeeding pattern had no effect on protein oxidation in the muscles studied (longissimus dorsi (LD), semitendinosus (ST) and supraspinatus (SP)). However, total antioxidant capacity decreased after food restriction (-51%, -43%, P < 0.01 for ST and LD muscles, respectively) and re-increased only after ad libitum refeeding. This alteration in the total antioxidant status can partially be explained by the similar pattern of change observed in the glutathione concentration of the muscles (-25%, P < 0.05 for ST muscle and NS for the other muscles). However, none of the concentrations of other water-soluble antioxidants studied (carnosine, anserine, glutathione peroxidase and superoxide dismutase) were altered during compensatory growth. This study showed that an inappropriate feeding level following a nutritional stress induced alterations in the total antioxidant status (particularly that of glutathione), which may have consequences on animal health. Other consequences of a decrease of the animal antioxidant status in vivo could be an alteration of the protein oxidation processes during meat maturation.

Therapeutic paracetamol treatment in older persons induces dietary and metabolic modifications related to sulfur amino acids

Sulfur amino acids are determinant for the detoxification of paracetamol (N-acetyl-p-aminophenol) through sulfate and glutathione conjugations. Long-term paracetamol treatment is common in the elderly, despite a potential cysteine/glutathione deficiency. Detoxification could occur at the expense of anti-oxidative defenses and whole body protein stores in elderly. We tested how older persons satisfy the extra demand in sulfur amino acids induced by long-term paracetamol treatment, focusing on metabolic and nutritional aspects. Effects of 3 g/day paracetamol for 14 days on fasting blood glutathione, plasma amino acids and sulfate, urinary paracetamol metabolites, and urinary metabolomic were studied in independently living older persons (five women, five men, mean (±SEM) age 74 ± 1 years). Dietary intakes were recorded before and at the end of the treatment and ingested sulfur amino acids were evaluated. Fasting blood glutathione, plasma amino acids, and sulfate were unchanged. Urinary nitrogen excretion supported a preservation of whole body proteins, but large-scale urinary metabolomic analysis revealed an oxidation of some sulfur-containing compounds. Dietary protein intake was 13% higher at the end than before paracetamol treatment. Final sulfur amino acid intake reached 37 mg/kg/day. The increase in sulfur amino acid intake corresponded to half of the sulfur excreted in urinary paracetamol conjugates. In conclusion, older persons accommodated to long-term paracetamol treatment by increasing dietary protein intake without any mobilization of body proteins, but with decreased anti-oxidative defenses. The extra demand in sulfur amino acids led to a consumption far above the corresponding population-safe recommendation.

Acetaminophen metabolism after major surgery: a greater challenge with increasing age

Patients undergoing major surgery represent a good model for the study of the hepatic metabolism of acetaminophen (APAP) after surgery and for the evaluation of how the detoxification process is influenced by aging. Thirty patients received intravenous APAP (1 g/6 h) for 4 days (D1-D4). Daily 24-h urinary metabolites-cysteine-APAP, mercapturate-APAP, APAP, and glucuronide and sulfate conjugates-as well as blood glutathione levels were compared with repeated-measures analysis of variance (significance, P<0.05). Between D1 and D4, cysteine-APAP increased (308±308 mg vs. 570±512 mg, P=0.005), and sulfate and glucuronide conjugates decreased (1,365±1,084 mg vs. 694±600 mg, P<0.0001 and 2,418±817 mg vs. 1,513±1,076 mg, P=0.011, respectively). Blood glutathione decreased (790±125 vs. 623±132 µmol/l, P<0.0001. These changes increased with aging. APAP disposition after major surgery shifts toward the oxidative pathways of metabolism, and this is enhanced with aging. Supplementation with sulfur-containing amino acids should be investigated further as it might minimize the effect on antioxidant defenses, especially in older persons undergoing more extensive surgical procedures.

B-vitamin deficiency is protective against DSS-induced colitis in mice

Vitamin deficiencies are common in patients with inflammatory bowel disease (IBD). Homocysteine (Hcys) is a thrombogenic amino acid produced from methionine (Met), and its increase in patients with IBD indicates a disruption of Met metabolism; however, the role of Hcys and Met metabolism in IBD is not well understood. We hypothesized that disrupted Met metabolism from a B-vitamin-deficient diet would exacerbate experimental colitis. Mice were fed a B(6)-B(12)-deficient or control diet for 2 wk and then treated with dextran sodium sulfate (DSS) to induce colitis. We monitored disease activity during DSS treatment and collected plasma and tissue for analysis of inflammatory tissue injury and Met metabolites. We also quantified Met cycle activity by measurements of in vivo Met kinetics using [1-(13)C-methyl-(2)H(3)]methionine infusion in similarly treated mice. Unexpectedly, we found that mice given the B-vitamin-deficient diet had improved clinical outcomes, including increased survival, weight maintenance, and reduced disease scores. We also found lower histological disease activity and proinflammatory gene expression (TNF-α and inducible nitric oxide synthase) in the colon in deficient-diet mice. Metabolomic analysis showed evidence that these effects were associated with deficient B(6), as markers of B(12) function were only mildly altered. In vivo methionine kinetics corroborated these results, showing that the deficient diet suppressed transsulfuration but increased remethylation. Our findings suggest that disrupted Met metabolism attributable to B(6) deficiency reduces the inflammatory response and disease activity in DSS-challenged mice. These results warrant further human clinical studies to determine whether B(6) deficiency and elevated Hcys in patients with IBD contribute to disease pathobiology.

Cysteine fluxes across the portal-drained viscera of enterally fed minipigs: effect of an acute intestinal inflammation

Cysteine is considered as a conditionally indispensable amino acid. Its dietary supply should thus be increased when endogenous synthesis cannot meet metabolic need, such as during inflammatory diseases. However, studies in animal models suggest a high first-pass extraction of dietary cysteine by the intestine, limiting the interest for an oral supplementation. We investigated here unidirectional fluxes of cysteine across the portal-drained viscera (PDV) of multi-catheterized minipigs, using simultaneous intragastric L-[(15)N] cysteine and intravenous L-[3,3D2] cysteine continuous infusions. We showed that in minipigs fed with an elemental enteral solution, cysteine first-pass extraction by the intestine is about 60% of the dietary supply, and that the PDV does not capture arterial cysteine. Beside dietary cysteine, the PDV release non-dietary cysteine (20% of the total cysteine release), which originates either from tissue metabolism or from reabsorption of endogenous secretion, such as glutathione (GSH) biliary excretion. Experimental ileitis induced by local administration of trinitrobenzene sulfonic acid, increased liver and ileal GSH fractional synthesis rate during the acute phase of inflammation, and increased whole body flux of cysteine. However, cysteine uptake and release by the PDV were not affected by ileitis, suggesting an adaptation of the intestinal sulfur amino acid metabolism in order to cover the additional requirement of cysteine linked to the increased GSH synthesis. We conclude that the small intestine sequesters large amounts of dietary cysteine during absorption, limiting its release into the bloodstream, and that the other tissues of the PDV (colon, stomach, pancreas, spleen) preferentially use circulating methionine or cysteine-containing peptides to cover their cysteine requirement.

Antioxidant supplementation had positive effects in old rat muscle, but through better oxidative status in other organs

OBJECTIVE

Aged muscle is characterized by a defect in the ability of leucine to stimulate protein synthesis. We showed previously that antioxidant supplementation improved the anabolic response to leucine of old muscle and reduced inflammation. The aim of the present study was to determine if the positive effects observed in muscle could be related to an improvement of local muscle oxidative status.

METHODS

Two groups of 20-mo-old male Wistar rats were supplemented or not with rutin, vitamin E, vitamin A, zinc, and selenium during 7 wk. We measured body weight, food intake, oxidative status in muscle and other tissues, gastrocnemius muscle proteolytic activities, and liver glutathione metabolism.

RESULTS

Antioxidant supplementation had no effect on muscle antioxidant capacity, superoxide dismutase activities, and myofibrillar protein carbonyl content and induced an increase in muscle cathepsin activities. In other tissues, antioxidant supplementation increased liver glutathione (reduced plus oxidized glutathione) content, reduced oxidative damage in the liver and spleen (as measured by γ-keto-aldehyde content), and reduced heart thiobarbituric acid-reactive substances.

CONCLUSION

Our results showed that the positive effects of antioxidant supplementation observed previously on the anabolic response to leucine of old muscle were not directly related to an improvement of in situ muscle oxidative status. It could result from reduced systemic inflammation/oxidative stress. The dialog between muscle and other organs should be studied more thoroughly, especially during aging.

Safety Assessment ofLactobacillus fermentumCECT5716, a probiotic strain isolated from human milk

Lactobacillus fermentumCECT5716, a probiotic strain isolated from human milk, was characterized in a previous study. The objective of this study was to evaluate its sensitivity to antibiotics and its potential toxicity and translocation ability after oral administration to mice. For this puropose, 40 Balb/C mice were divided in two groups (n=20 per group). One group was treated orally with 1010colony forming units (cfu)/mouse/day ofLb. fermentumCECT5716 during 28 d. The other group only received the excipient and was used as control. Food intake, body weight, bacterial translocation and different biochemical and haematological parameters were analysed. Oral administration ofLb. fermentumCECT5716 to mice had no adverse effects on mice. There were no significant differences in body weight or food intake between control and probiotic-treated mice. No bacteraemia was observed and there was no treatment-associated bacterial translocation to liver or spleen. Stress oxidative markers were not different in control and probiotic-treated mice. These results suggest that the strainLb. fermentumCECT5716 is non-pathogenic for mice even in doses 10,000 times higher (expressed per kg of body weight) than those normally consumed by humans.

Methionine metabolism in an animal model of sepsis

BACKGROUND

Sepsis is a disease with high incidence and lethality and is accompanied by profound metabolic disturbances. In mammalian methionine metabolism, S-adenosylmethionine (SAM) is produced, which is important in the synthesis of neurotransmitters and glutathione and as an anti-inflammatory agent. The degradation product and antagonist of SAM is S-adenosylhomocysteine (SAH). In this study, we investigated changes in methionine metabolism in a rodent model of sepsis.

METHODS

Sepsis was induced in male Wistar rats (n=21) by intraperitoneal injection of bacterial lipopolysaccharide (10 mg/kg). Controls (n=18) received vehicle only. Blood was collected by cardiac puncture 24 h later. Puncture of the suboccipital fossa was performed to collect cerebrospinal fluid (CSF). Methionine metabolites were measured using stable isotope dilution tandem mass spectrometry. Plasma total homocysteine and cysteine were measured by HPLC using fluorescence detection. Glutathione was assayed using a modified enzymatic microtiter plate assay.

RESULTS

We observed significantly higher plasma levels of SAM (p<0.001) and SAM/SAH ratio (p=0.004) in septic animals. In CSF, there was also a trend for higher levels of SAM in septic animals (p=0.067). Oxidative stress was reflected by an increase in the ratio of oxidized/reduced glutathione in septic animals (p=0.001).

CONCLUSIONS

Sepsis is associated with an increase in SAM/SAH ratio in plasma and CSF in rodents. This indicates an altered methylation potential during sepsis, which may be relevant for sepsis-associated impairment of transmethylation reactions, circulation and defense against oxidative stress. If verified in humans, such findings could lead to novel strategies for supportive treatment of sepsis, as methionine metabolism can easily be manipulated by dietary strategies.

Liver proteomics for therapeutic drug discovery: inhibition of the cyclophilin receptor CD147 attenuates sepsis-induced acute renal failure

OBJECTIVE

Sepsis-induced multi-organ failure continues to have a high mortality. The liver is an organ central to the disease pathogenesis. The objective of this study was to identify the liver proteins that change in abundance with sepsis and subsequently identify new drug targets.

DESIGN

Proteomic discovery study and drug target validation. For the proteomics study, three biological replicate mice were used per group.

SETTING

Research institute laboratory.

SUBJECTS

Three-month-old C57BL/6 mice.

INTERVENTIONS

We used a mouse model of sepsis based on cecal ligation and puncture, but with fluid and antibiotic resuscitation. Liver proteins that changed in abundance were identified by difference in gel electrophoresis. We compared liver proteins from 6-hr post-cecal ligation and puncture to sham-operated mice ("early proteins") and 24-hr post-cecal ligation and puncture with 6-hr post-cecal ligation and puncture ("late proteins"). Proteins that changed in abundance were identified by tandem mass spectrometry. We then inhibited the receptor for one protein and determined the effect on sepsis-induced organ dysfunction.

RESULTS

The liver proteins that changed in abundance after sepsis had a range of functions such as acute phase response, coagulation, endoplasmic reticulum stress, oxidative stress, apoptosis, mitochondrial electron transfer proteins, and nitric oxide metabolism. We found that cyclophilin increased in abundance after cecal ligation and puncture. When the receptor for this protein, CD147, was inhibited, sepsis-induced renal dysfunction was reduced. There was also a significant reduction in serum cytokine production when CD147 was inhibited.

CONCLUSION

By applying proteomics to a clinically relevant mouse model of sepsis, we identified a number of novel proteins that changed in abundance. The inhibition of the receptor for one of these proteins, cyclophilin, attenuated sepsis-induced acute renal failure. The application of proteomics to sepsis research can facilitate the discovery of new therapeutic targets.

Safety assessment of the human milk-isolated probiotic Lactobacillus salivarius CECT5713

The potential probiotic bacteria Lactobacillus salivarius CECT5713 has recently been isolated from human milk and characterized. The objective of the present study was to evaluate the oral toxicity of this potential probiotic bacteria in mice. With this aim, 50 Balb/C mice were divided in 5 groups (n = 10). Three of these groups were treated orally with different doses of L. salivarius CECT5713: 5 x 10(8), 2 x 10(9), or 10(10) cfu/mouse per d for 28 d. One additional group was administered the vehicle alone and was used as a control. The last group were injected intraperitoneally with 10(8) cfu/mouse in a single dose and killed 2 (n = 5) and 5 (n = 5) d after intraperitoneal injection. Food intake, body weight, bacterial translocation, serum alpha-amyloid protein, and different biochemical parameters were analyzed. Oral administration of L. salivarius CECT5713 to mice had no adverse effects on mouse body weight or food intake. No bacteremia was shown and there was no treatment-associated bacterial translocation to the liver or spleen. Intraperitoneal administration caused a significant bacterial translocation to the liver and spleen, but not to the blood. However, this translocation was not related to illness or death at either d 2 or d 5, although an increase in plasma serum alpha-amyloid protein was observed at d 2. These results suggest that the strain L. salivarius CECT5713 is nonpathogenic for mice, even in doses 10,000 times higher (expressed per kilograms of body weight) than those normally consumed by humans. Thus, this strain is likely to be safe for human consumption.

Comparison of lycopene and tomato effects on biomarkers of oxidative stress in vitamin E deficient rats

BACKGROUND

Cohort studies suggested that individuals with higher intake of tomatoes and tomato products have a lower risk of degenerative diseases. Lycopene, an antioxidant and antiproliferative carotenoid, has been hypothesized to be responsible for the health benefits of tomatoes. However, studies demonstrated a higher potential of tomatoes compared to lycopene to reduce oxidative stress or carcinogenesis.

AIM OF THE STUDY

Our study aimed at distinguishing lycopene effect from that of tomato on oxidative stress, by using yellow tomato, a tomato variety devoid of lycopene.

METHODS

Effects of feeding with none (control), 16% freeze-dried yellow tomato (YT), 16% freeze-dried red tomato (RT) or 0.05% lycopene beadlets (LB) were compared in a rat model with mild oxidative stress induced by low vitamin E diet (LVED). Four groups of 10 rats were fed ad libitum for 6 weeks. Physiological parameters such as ingesta, body, spleen and liver weights, cholesterol and triglycerides (TG) levels were assessed. Lycopene and vitamin E concentrations and oxidative stress biomarkers were measured in the plasma and/or liver and/or heart tissue of the rats.

RESULTS

RT, YT, and LB had no effect on rats' ingesta, body and spleen weights. RT, YT and LB had no effect on plasma cholesterol concentration. RT decreased TG level compared to control, YT and LB (P < 0.05). Rats fed RT or LB accumulated lycopene in plasma in contrast with rats fed YT. Heart level of thiobarbituric reactive species (TBARS) in rats fed RT or YT was lower than that in the control and the LB fed rats (P < 0.05). Despite similar concentrations of lycopene in plasma and liver, rats fed LB showed a significantly higher heart level of TBARS than rats fed tomatoes. RT increased erythrocyte superoxide dismutase (eSOD) activity compared with LB and nitric oxide (NO) level compared with control and LB. LB decreased ferric reducing ability of plasma (FRAP) level compared with control, RT and LB (P < 0.05).

CONCLUSION

Our study showed for the first time that tomatoes, containing or not containing lycopene, have a higher potential than lycopene to attenuate and or to reverse oxidative stress-related parameters in a mild oxidative stress context.

Induction of cystine/glutamate transporter in bacterial lipopolysaccharide induced endotoxemia in mice

BACKGROUND

Cystine/glutamate transporter, system xc-, contributes to the maintenance of intracellular glutathione levels and the redox balance in the extracellular space. The main component of the transporter, xCT, is known to be strongly induced by various stimuli like oxidative stress in mammalian cultured cells. We examined the expression of xCT mRNA in vivo in the experimental endotoxemia.

METHODS

Northern blot analysis and in situ hybridization were used to investigate the expression of xCT mRNA in the tissues of the mice exposed to bacterial lipopolysaccharide (LPS).

RESULTS

Northern blot analysis revealed that xCT mRNA was constitutively expressed in the brain, thymus, and spleen, and that the expression of xCT mRNA was strongly up-regulated in thymus and spleen by the administration of a sublethal dose of LPS. In addition to brain, thymus, and spleen, xCT mRNA was detected also in the bronchiolar epithelium of the lung by the administration of the lethal dose of LPS.

CONCLUSION

xCT is induced in some specific tissues by the administration of LPS. The results suggest that cystine/glutamate transporter plays an important role under the inflammatory conditions.

Mechanisms through which sulfur amino acids control protein metabolism and oxidative status

Amino acids regulate protein synthesis and breakdown (i.e., protein turnover) and consequently protein deposition, which corresponds to the balance between the two processes. Elucidating the mechanisms involved in such regulation is important from fundamental and applied points of view since it can provide a basis to optimize amino acid requirements and to control protein mass, body composition and so forth. Amino acids, which have long been considered simply as precursors of protein synthesis, are now recognized to exert other significant influences; that is, they are precursors of essential molecules, act as mediators or signal molecules and affect numerous functions. For example, amino acids act as mediators of metabolic pathways in the same manner as certain hormones. Thus, they modulate the activity of intracellular protein kinases involved in the regulation of metabolic pathways such as mRNA translation. We provide here an overview of the roles of amino acids as regulators of protein metabolism, by focusing particularly on sulfur amino acids. The potential importance of methionine as a "nutrient signal" is discussed in the light of recent findings. Emphasis is also placed on mechanisms controlling oxidative status since sulfur amino acids are involved in the synthesis of intracellular antioxidants (glutathione, taurine etc.) and in the methionine sulfoxide reductase antioxidant system.

Safety assessment of two probiotic strains, Lactobacillus coryniformis CECT5711 and Lactobacillus gasseri CECT5714

AIMS

The object of the present study was to evaluate the oral toxicity of the recently isolated probiotic bacteria Lactobacillus coryniformis CECT5711 and Lactobacillus gasseri CECT5714.

METHODS AND RESULTS

Enzymatic activity and antibiotic resistance profile were evaluated in vitro. Then, the oral toxicity was analysed by an in vivo experiment using 20 Balb/C mice, which were orally treated with CECT5711 or CECT5714 (10(10) CFU mouse(-1) day(-1)) during 30 days. Results showed that CECT5711 and CECT5714 have no deleterious enzymatic activities and present intrinsic antibiotic resistance profile. Administration of both strains to mice had no adverse effects on body weight or food intake. No bacteraemia was present in liver or spleen and there was no treatment-associated bacterial translocation to these tissues. Liver glutathione content as well as plasma malondialdehide concentration were not statistically different in probiotic-treated mice when compared with control mice. Probiotic treatment did not cause changes in the biochemical and haematological parameters analysed.

CONCLUSIONS

These results suggest that strains CECT5711 and CECT5714 are nonpathogenic and likely to be safe for human consumption.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study reveals the oral safety of two new lactobacilli strains that are aimed to be used as probiotics in food and pharmaceutical applications.

The biochemical basis of antioxidant therapy in critical illness

During critical illness free radical production may increase as a result of, for example, sepsis or tissue trauma. In addition, because of a potential for increased losses, and the possibility of inadequate nutrition, the antioxidant defences of the body may become compromised. Thus, the delicate balance between free radicals and antioxidants may be disturbed. Various nutritional and pharmacological strategies to enhance antioxidant defences have been proposed, which aim either to maintain or enhance endogenous antioxidant stores or to provide alternative antioxidant agents. Trace elements and amino acids are particularly important, and their synergistic role in the maintenance of the body's antioxidant defence network will be discussed.

Effect of an enteral diet supplemented with a specific blend of amino acid on plasma and muscle protein synthesis in ICU patients

BACKGROUND & AIM

Polytrauma patients are characterized by a negative nitrogen balance and muscle wasting. Standard nutrition is relatively inefficient to improve muscle protein turnover. The aim of this study was to investigate the effect of enteral nutrition (EN) supplemented with specific amino acids on protein metabolism in polytrauma patients.

METHODS

In a double blind study, 12 polytrauma patients were randomized to receive EN supplemented with either a mixture of cysteine, threonine, serine and aspartate (AA patients) or alanine at isonitrogenous levels (Ala patients). An intravenous infusion of l-[1-(13)C]-leucine was performed in the fed state between day 9 and 12 post-injury (Df) in patients and in a group of healthy volunteers (n=8) (EN+Ala) to measure whole body leucine kinetics, plasma and muscle protein synthesis rates. Nitrogen balance, 3-methyl histidine excretion were measured from day 3 to Df.

RESULTS

The contribution of total plasma proteins to whole body protein synthesis was greatly increased, from 11% in healthy volunteers to about 25% in polytrauma patients. AA supplementation had no effect on nitrogen balance, leucine kinetics or plasma protein synthesis in patients. In contrast, the urinary excretion of 3-methyl histidine tended to decrease along the study in the AA supplemented group compared to an increase in the Ala group. Muscle protein synthesis tended to be higher in the AA group than in the Ala group (46%, P=0.065).

CONCLUSION

During injury, an increased supply of cysteine, threonine, serine and aspartate could be able to better cover the specific amino requirements, thus resulting in improved muscle protein synthesis without impairment of acute phase protein synthesis.

Beneficial effect of amino acid supplementation, especially cysteine, on body nitrogen economy in septic rats

BACKGROUND AND AIMS

Muscle wasting and increased synthesis of proteins and compounds involved in host defense characterize severe injury. The aims of the studies reported were to determine which amino acids exhibited an increased tissue content linked to anabolic processes in infected rats by comparison with healthy pair-fed controls, and to explore whether diets supplemented with these amino acids attenuate the catabolic response to infection.

METHODS

Total amino acid content of the liver and the rest of the body were measured in control well-fed rats, in infected rats and their pair-fed controls 2 days after infection. In the nutritional protocols, infected rats were fed with a diet supplemented with alanine (basal diet), or threonine, serine, aspartate, asparagine and arginine (AA) or AA+cysteine (complete diet).

RESULTS

Infection significantly increased liver total amino acid content by 38% for most amino acids. In contrast, the percentage increase was cysteine 79.3, threonine 45.3, aspartate-asparagine 46.3 and serine 46.5. Whole body without liver content of most amino acids decreased after infection due to the catabolic response, while the content of cysteine increased by 6% (P<0.05) and those of threonine and arginine did not decrease. After infection, animals fed the complete diet lost less weight than animals fed the basal diet (P<0.05). Furthermore, AA plus cysteine supplementation reduced significantly urinary nitrogen excretion and muscle wasting.

CONCLUSIONS

The results provide evidence that diet supplementation with cysteine, threonine, serine, aspartate-asparagine and arginine supports the synthesis of vital proteins to spare body protein catabolism during infection.

Novel selenoorganic compounds as modulators of oxidative stress in blood platelets

Many selenoorganic compounds play an important role in biochemical processes and act as antioxidants, enzyme inhibitors, or drugs. The effects of five new synthesized selenoorganic compounds (2-(5-chloro-2-pyridyl)-7-azabenzisoselenazol-3(2H)-one; 2-phenyl-7-azabenzisoselenazol-3(2H)-one; 2-(pyridyl)-7-azabenzisoselenazol-3(2H)-one; 7-azabenzisoselenazol-3(2H)-one; bis(2-aminophenyl) diselenide) on oxidative changes in human blood platelets and in plasma were studied in vitro and compared with those of ebselen, a well known antioxidant. Our studies demonstrated that bis(2-aminophenyl) diselenide has distinctly protective effects against oxidative stress in blood platelets and in plasma. It might have greater biological relevance and stronger pharmacological effects than ebselen.

The effects of sulfur amino acid intake on immune function in humans

No direct data exist on the influence of supranormal intakes of sulfur amino acids on immune function in humans. However 3 major products of sulfur amino acids, glutathione (GSH), homocysteine (Hcy), and taurine (Tau), influence, mainly, inflammatory aspects of the immune response in vitro and in vivo. Methionine intakes above approximately 1 g/d transiently raise plasma Tau, Hcy, and GSH. Tau and GSH ameliorate inflammation. Hcy has the opposite effect. A biphasic relation, between cellular GSH and CD4+ and CD8+ numbers occurs in healthy men. How changes in sulfur amino acid intake influence this phenomenon is unknown. In animals, high Tau intakes are antiinflammatory. How immune function in humans is affected is unknown. A positive relation between plasma neopterin (a marker of a Th-1-type immune response) and Hcy indicates that Hcy may play a part in inflammatory aspects of Parkinson's disease and aging. In vitro, Hcy, at concentrations seen following consumption of approximately 6 g L-methionine/d in adults, increases the interactions among T lymphocytes, monocytes, and endothelium. Whether a similar phenomenon occurs in vivo is unknown. Polymorphisms in the methylenetetrahydrofolate reductase gene are associated with raised plasma Hcy in young but not old subjects. The relation of this observation to immune function is unknown. The relationships among Hcy, inflammatory aspects of disease, and in vitro alterations in immune cell behavior create a cautionary note about supplementation of diets with l-methionine to raise intake above approximately 1 g/d. Studies directly linking methionine intake, genetics, plasma Hcy, Tau, and GSH and immune function are needed.

Role of hydrogen sulfide in cecal ligation and puncture-induced sepsis in the mouse

Endogenous hydrogen sulfide (H2S) is naturally synthesized in various types of mammalian cells from l-cysteine in a reaction catalyzed by two enzymes, cystathionine-γ-lyase (CSE) and/or cystathionine-β-synthase. The latest studies have implied that H2S functions as a vasodilator and neurotransmitter. However, so far there is little information about the role played by H2S in systemic inflammation such as sepsis. Thus the aim of this study was to investigate the potential role of endogenous H2S in cecal ligation and puncture (CLP)-induced sepsis. Male Swiss mice were subjected to CLP-induced sepsis and treated with saline (ip), dl-propargylglycine (PAG, 50 mg/kg ip), a CSE inhibitor, or sodium hydrosulfide (NaHS; 10 mg/kg ip). PAG was administered either 1 h before or 1 h after the induction of sepsis, whereas NaHS was given at the same time of CLP. CLP-induced sepsis significantly increased the plasma H2S level and the liver H2S synthesis 8 h after CLP compared with sham operation. Induction of sepsis also resulted in a significant upregulation of CSE mRNA in liver. On the other hand, prophylactic as well as therapeutic administration of PAG significantly reduced sepsis-associated systemic inflammation, as evidenced by myeloperoxidase activity and histological changes in lung and liver, and attenuated the mortality of CLP-induced sepsis. Injection of NaHS significantly aggravated sepsis-associated systemic inflammation. Therefore, the effect of inhibition of H2S formation and administration of NaHS suggests that H2S plays a proinflammatory role in regulating the severity of sepsis and associated organ injury.

Methionine kinetics are altered in the elderly both in the basal state and after vaccination

BACKGROUND

Inflammation is known to affect sulfur amino acid metabolism. Aging is associated with an increased prevalence of inflammatory conditions, but the metabolism of methionine has been poorly explored in the elderly.

OBJECTIVES

The aims of this study were to compare methionine kinetics between elderly and young subjects and to explore the effect of aging on the response to a mild inflammatory challenge induced by a vaccination.

DESIGN

Seven elderly volunteers aged 66-76 y and 8 young volunteers aged 22-26 y were studied before and 2 d after a vaccination (diphtheria, tetanus, poliomyelitis, and typhoid vaccines). Methionine kinetics were measured by using an infusion of L-[1-13C, methyl-2H3]methionine in the postabsorptive and fed states.

RESULTS

Before vaccination, the contribution of homocysteine remethylation to methionine-methyl flux (Qm) and the ratio of remethylation to homocysteine transsulfuration were significantly lower in the elderly subjects than in the young subjects (P < 0.05). In contrast, the contribution of transsulfuration to methionine transmethylation was higher in the elderly (P < 0.05). Vaccination significantly increased the ratio of transsulfuration to transmethylation and decreased the ratio of remethylation to Qm (P < 0.05).

CONCLUSIONS

The preferential methionine metabolism toward cysteine synthesis observed after vaccination suggests an increased requirement of sulfur amino acids even in mild inflammatory situations. The main finding of this study is a higher proportion of methionine entering the transsulfuration pathway in elderly subjects before vaccination. This finding suggests an increased cysteine demand during aging.