Inositol and mannose utilization rates in term and late-preterm infants exceed nutritional intakes

Wide-genome selection of lactic acid bacteria harboring genes that promote the elimination of antinutritional factors

Anti-nutritional factors (ANFs) substances in plant products, such as indigestible non-starchy polysaccharides (α-galactooligosaccharides, α-GOS), phytate, tannins, and alkaloids can impede the absorption of many critical nutrients and cause major physiological disorders. To enhance silage quality and its tolerance threshold for humans as well as other animals, ANFs must be reduced. This study aims to identify and compare the bacterial species/strains that are potential use for industrial fermentation and ANFs reduction. A pan-genome study of 351 bacterial genomes was performed, and binary data was processed to quantify the number of genes involved in the removal of ANFs. Among four pan-genomes analysis, all 37 tested Bacillus subtilis genomes had one phytate degradation gene, while 91 out of 150 Enterobacteriacae genomes harbor at least one genes (maximum three). Although, no gene encoding phytase detected in genomes of Lactobacillus and Pediococcus species, they have genes involving indirectly in metabolism of phytate-derivatives to produce Myo-inositol, an important compound in animal cells physiology. In contrast, genes related to production of lectin, tannase and saponin degrading enzyme did not include in genomes of B. subtilis and Pediococcus species. Our findings suggest a combination of bacterial species and/or unique strains in fermentation, for examples, two Lactobacillus strains (DSM 21115 and ATCC 14869) with B. subtilis SRCM103689, would maximize the efficiency in reducing the ANFs concentration. In conclusion, this study provides insights into bacterial genomes analysis for maximizing nutritional value in plant-based food. Further investigations of gene numbers and repertories correlated to metabolism of different ANFs will help clarifying the efficiency of time consuming and food qualities.

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.

Milk polar lipids composition and functionality: a systematic review

Polar lipids including glycerophospholipids and sphingophospholipids are important nutrients and milk is a major source, particularly for infants. This systematic review describes the human and bovine milk polar lipid composition, structural organization, sources for formulation, and physiological functionality. A total of 2840 records were retrieved through Scopus, 378 were included. Bovine milk is a good source of polar lipids, where yield and composition are highly dependent on the choice of dairy streams and processing. In milk, polar lipids are organized in the milk fat globule membrane as a tri-layer encapsulating triglyceride. The overall polar lipid concentration in human milk is dependent on many factors including lactational stage and maternal diet. Here, reasonable ranges were determined where possible. Similar for bovine milk, where differences in milk lipid concentration proved the largest factor determining variation. The role of milk polar lipids in human health has been demonstrated in several areas and critical review indicated that brain, immune and effects on lipid metabolism are best substantiated areas. Moreover, insights related to the milk fat globule membrane structure-function relation as well as superior activity of milk derived polar lipid compared to plant-derived sources are emerging areas of interest regarding future research and food innovations.

Blood myo-inositol concentrations in preterm and term infants

OBJECTIVE

To describe relationship between cord blood (representing fetal) myo-inositol concentrations and gestational age (GA) and to determine trends of blood concentrations in enterally and parenterally fed infants from birth to 70 days of age.

DESIGN/METHODS

Samples were collected in 281 fed or unfed infants born in 2005 and 2006. Myo-inositol concentrations were displayed in scatter plots and analyzed with linear regression models of natural log-transformed values.

RESULTS

In 441 samples obtained from 281 infants, myo-inositol concentrations varied from nondetectable to 1494 μmol/L. Cord myo-inositol concentrations decreased an estimated 11.9% per week increase in GA. Postnatal myo-inositol concentrations decreased an estimated 14.3% per week increase in postmenstrual age (PMA) and were higher for enterally fed infants compared to unfed infants (51% increase for fed vs. unfed infants).

CONCLUSIONS

Fetal myo-inositol concentrations decreased with increasing GA. Postnatal concentrations decreased with increasing PMA and were higher among enterally fed than unfed infants.

Nuclear Magnetic Resonance-Based Metabolomic Comparison of Breast Milk and Organic and Traditional Formula Milk Brands for Infants and Toddlers

In recent years, new formula milk (FM) products based on milk from farms that strictly adhere to the "organic farming" practices became available. However, little is known about the differences in nutritional profile of these organic formulae with respect to traditional ones. We comprehensively evaluated the metabolite profiles of FM with nuclear magnetic resonance (NMR)-based metabolomic analysis. Five commercial brands of organic and nonorganic formula liquid milk for infants (0-12 months) and toddlers (1-3 years) were analyzed, together with human milk (HM) samples. Proton NMR (¹H NMR) spectroscopy mapped molecular characteristics of FM linked to different production techniques, and identified differences between FM and HM samples. We performed a metabolic fingerprint analysis using multivariate and univariate statistical techniques. A clear distinction is found among different commercial brands of the FM samples. In addition, several differences in metabolomic profiles of FM have been found in comparison with HM for the first time. Notably, it was possible to identify, both in the formulations for toddlers and for infants, metabolites that vary in concentration between the formulae produced with milk obtained according to organic farming techniques, and those produced using nonorganic milk. In particular, organic and nonorganic formulations are differentiated by the levels of glucose, methionine, o-phosphocholine, butyrate, hippurate, creatine, and dimethyl sulfone. Importantly, the HM appeared to differ from both organic and nonorganic brands in a context of metabolites. These findings inform efforts to design FM in ways that closely mimic HM, and guide research to differentiate organic and traditional FM.

Myo-inositol: its metabolism and potential implications for poultry nutrition-a review

Myo-inositol (MI) has gained relevance in physiology research during the last decade. As a constituent of animal cells, MI was proven to be crucial in several metabolic and regulatory processes. Myo-inositol is involved in lipid signaling, osmolarity, glucose, and insulin metabolism. In humans and rodents, dietary MI was assessed to be important for health so that MI supplementation appeared to be a valuable alternative for treatment of several diseases as well as for improvements in metabolic performance. In poultry, there is a lack of evidence not only related to specific species-linked metabolic processes but also about the effects of dietary MI on performance and health. This review intends to provide information about the meaning of dietary MI in animal metabolism as well as to discuss potential implications of dietary MI in poultry health and performance with the aim to identify open questions in poultry research.

Skeletal muscle protein accretion rates and hindlimb growth are reduced in late gestation intrauterine growth-restricted fetal sheep

KEY POINTS

Adults who were affected by intrauterine growth restriction (IUGR) suffer from reductions in muscle mass, which may contribute to insulin resistance and the development of diabetes. We demonstrate slower hindlimb linear growth and muscle protein synthesis rates that match the reduced hindlimb blood flow and oxygen consumption rates in IUGR fetal sheep. These adaptations resulted in hindlimb blood flow rates in IUGR that were similar to control fetuses on a weight-specific basis. Net hindlimb glucose uptake and lactate output rates were similar between groups, whereas amino acid uptake was significantly lower in IUGR fetal sheep. Among all fetuses, blood O₂ saturation and plasma glucose, insulin and insulin-like growth factor-1 were positively associated and norepinephrine was negatively associated with hindlimb weight. These results further our understanding of the metabolic and hormonal adaptations to reduced oxygen and nutrient supply with placental insufficiency that develop to slow hindlimb growth and muscle protein accretion.

ABSTRACT

Reduced skeletal muscle mass in the fetus with intrauterine growth restriction (IUGR) persists into adulthood and may contribute to increased metabolic disease risk. To determine how placental insufficiency with reduced oxygen and nutrient supply to the fetus affects hindlimb blood flow, substrate uptake and protein accretion rates in skeletal muscle, late gestation control (CON) (n = 8) and IUGR (n = 13) fetal sheep were catheterized with aortic and femoral catheters and a flow transducer around the external iliac artery. Muscle protein kinetic rates were measured using isotopic tracers. Hindlimb weight, linear growth rate, muscle protein accretion rate and fractional synthetic rate were lower in IUGR compared to CON (P < 0.05). Absolute hindlimb blood flow was reduced in IUGR (IUGR: 32.9 ± 5.6 ml min^-1 ; CON: 60.9 ± 6.5 ml min^-1 ; P < 0.005), although flow normalized to hindlimb weight was similar between groups. Hindlimb oxygen consumption rate was lower in IUGR (IUGR: 10.4 ± 1.4 μmol min^-1  100 g^-1 ; CON: 14.7 ± 1.3 μmol min^-1  100 g^-1 ; P < 0.05). Hindlimb glucose uptake and lactate output rates were similar between groups, whereas amino acid uptake was lower in IUGR (IUGR: 1.3 ± 0.5 μmol min^-1  100 g^-1 ; CON: 2.9 ± 0.2 μmol min^-1  100 g^-1 ; P < 0.05). Blood O₂ saturation (r²  = 0.80, P < 0.0001) and plasma glucose (r²  = 0.68, P < 0.0001), insulin (r²  = 0.40, P < 0.005) and insulin-like growth factor (IGF)-1 (r²  = 0.80, P < 0.0001) were positively associated and norepinephrine (r²  = 0.59, P < 0.0001) was negatively associated with hindlimb weight. Slower hindlimb linear growth and muscle protein synthesis rates match reduced hindlimb blood flow and oxygen consumption rates in the IUGR fetus. Metabolic adaptations to slow hindlimb growth are probably hormonally-mediated by mechanisms that include increased fetal norepinephrine and reduced IGF-1 and insulin.

Potential Nutrients for Preventing or Treating Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is a frequent complication occurring in extremely preterm infants. Despite recent advances in newborn medicine, the incidence of BPD does not appear to have changed markedly, and specific treatments and prevention strategies are still lacking. Nutrition plays an important role in normal lung development and maturation. Malnutrition may delay somatic growth and new alveoli development, thus aggravating pulmonary injury involved in the pathogenesis of BPD. However, few nutrients have been investigated for their potential to mitigate the pathogenesis of BPD. In this article, we reviewed the recent progress in research on potential nutrients useful for the prevention or treatment of BPD, including glutamine, cysteine and N-acetylcysteine, L-arginine and L-citrulline, long chain polyunsaturated fatty acids (LCPUFAs), inositol, selenium, and some antioxidant vitamins including vitamin A. Current evidence shows that vitamin A and LCPUFA can prevent BPD, and that L-citrulline might provide a new method to treat chronic pulmonary hypertension associated with BPD in premature infants. The effects of other nutrients on BPD prevention need to be further studied.

Safety and pharmacokinetics of multiple dose myo-inositol in preterm infants

BACKGROUND

Preterm infants with respiratory distress syndrome (RDS) given inositol had reduced bronchopulmonary dysplasia (BPD), death and severe retinopathy of prematurity (ROP). We assessed the safety and pharmacokinetics of daily inositol to select a dose providing serum levels previously associated with benefit, and to learn if accumulation occurred when administered throughout the normal period of retinal vascularization.

METHODS

Infants ≤ 29 wk GA (n = 122, 14 centers) were randomized and treated with placebo or inositol at 10, 40, or 80 mg/kg/d. Intravenous administration converted to enteral when feedings were established, and continued to the first of 10 wk, 34 wk postmenstrual age (PMA) or discharge. Serum collection employed a sparse sampling population pharmacokinetics design. Inositol urine losses and feeding intakes were measured. Safety was prospectively monitored.

RESULTS

At 80 mg/kg/d mean serum levels reached 140 mg/l, similar to Hallman's findings. Levels declined after 2 wk, converging in all groups by 6 wk. Analyses showed a mean volume of distribution 0.657 l/kg, clearance 0.058 l/kg/h, and half-life 7.90 h. Adverse events and comorbidities were fewer in the inositol groups, but not significantly so.

CONCLUSION

Multiple dose inositol at 80 mg/kg/d was not associated with increased adverse events, achieves previously effective serum levels, and is appropriate for investigation in a phase III trial.

Interventions To Prevent Retinopathy of Prematurity: A Meta-analysis

CONTEXT

The effectiveness of many interventions aimed at reducing the risk of retinopathy has not been well established.

OBJECTIVE

To estimate the effectiveness of nutritional interventions, oxygen saturation targeting, blood transfusion management, and infection prevention on the incidence of retinopathy of prematurity (ROP).

DATA SOURCES

A comprehensive search of several databases was conducted, including Medline, Embase, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and Scopus through March 2014.

STUDY SELECTION

We included studies that evaluated nutritional interventions, management of supplemental oxygen, blood transfusions, or infection reduction and reported the incidence of ROP and mortality in neonates born at <32 weeks.

DATA EXTRACTION

We extracted patient characteristics, interventions, and risk of bias indicators. Outcomes of interest were any stage ROP, severe ROP or ROP requiring treatment, and mortality.

RESULTS

We identified 67 studies enrolling 21 819 infants. Lower oxygen saturation targets reduced the risk of developing any stage ROP (relative risk [RR] 0.86, 95% confidence interval [CI], 0.77-0.97) and severe ROP or ROP requiring intervention (RR 0.58, 95% CI, 0.45-0.74) but increased mortality (RR 1.15, 95% CI, 1.04-1.29). Aggressive parenteral nutrition reduced the risk of any stage ROP but not severe ROP. Supplementation of vitamin A, E, or inositol and breast milk feeding were beneficial but only in observational studies. Use of transfusion guidelines, erythropoietin, and antifungal agents were not beneficial.

LIMITATIONS

Results of observational studies were not replicated in randomized trials. Interventions were heterogeneous across studies.

CONCLUSIONS

At the present time, there are no safe interventions supported with high quality evidence to prevent severe ROP.

Inositol Analysis by HPLC and Its Stability in Scavenged Sample Conditions

Inositol is a 6-carbon sugar alcohol that has been shown in limited studies to reduce retinopathy of prematurity and chronic lung disease in premature newborns. Developmentally it has a high concentration in the fetus that decreases with gestational age. It is transported from the fetus to the mother across the placenta. Although studies are underway to determine inositol kinetics in premature newborns treated therapeutically, the effects of gestational age, age after birth, and feeding on inositol concentrations after birth have not been studied adequately in premature newborns. Such studies would minimize blood removal and trauma in preterm newborns by using plasma samples scavenged from the clinical laboratory to measure inositol after birth, if they remain stable. This report describes a new high pressure liquid chromatographic assay for inositol and its use to study the stability of inositol in conditions of storage that might be encountered within the clinical laboratory. The assay is linear from 0 to 1000 Mm with a lower limit of quantitation of 50 μM. Inositol in human plasma remains stable in refrigeration and at room temperature for up to 14 days and is not affected by storage in red blood cells that are intact or lysed. Anticoagulants encountered in clinical blood samples do not interfere with the chromatograms. Thus, it is feasible to measure the changes in inositol concentrations in plasma from preterm newborns that is scavenged from the clinical laboratory after storage for as long as 14 days.

Locust bean gum safety in neonates and young infants: an integrated review of the toxicological database and clinical evidence

Locust bean gum (LBG) is a galactomannan polysaccharide used as thickener in infant formulas with the therapeutic aim to treat uncomplicated gastroesophageal reflux (GER). Since its use in young infants below 12weeks of age is not explicitly covered by the current scientific concept of the derivation of health based guidance values, the present integrated safety review aimed to compile all the relevant preclinical toxicological studies and to combine them with substantial evidence gathered from the clinical paediatric use as part of the weight of evidence supporting the safety in young infants below 12weeks of age. LBG was demonstrated to have very low toxicity in preclinical studies mainly resulting from its indigestible nature leading to negligible systemic bioavailability and only possibly influencing tolerance. A standard therapeutic level of 0.5g/100mL in thickened infant formula is shown to confer a sufficiently protective Margin of Safety. LBG was not associated with any adverse toxic or nutritional effects in healthy term infants, while there are limited case-reports of possible adverse effects in preterms receiving the thickener inappropriately. Altogether, it can be concluded that LBG is safe for its intended therapeutic use in term-born infants to treat uncomplicated regurgitation from birth onwards.

Changes in fetal mannose and other carbohydrates induced by a maternal insulin infusion in pregnant sheep

BACKGROUND

The importance of non-glucose carbohydrates, especially mannose and inositol, for normal development is increasingly recognized. Whether pregnancies complicated by abnormal glucose transfer to the fetus also affect the regulation of non-glucose carbohydrates is unknown. In pregnant sheep, maternal insulin infusions were used to reduce glucose supply to the fetus for both short (2-wk) and long (8-wk) durations to test the hypothesis that a maternal insulin infusion would suppress fetal mannose and inositol concentrations. We also used direct fetal insulin infusions (1-wk hyperinsulinemic-isoglycemic clamp) to determine the relative importance of fetal glucose and insulin for regulating non-glucose carbohydrates.

RESULTS

A maternal insulin infusion resulted in lower maternal (50%, P < 0.01) and fetal (35-45%, P < 0.01) mannose concentrations, which were highly correlated (r(2) = 0.69, P < 0.01). A fetal insulin infusion resulted in a 50% reduction of fetal mannose (P < 0.05). Neither maternal nor fetal plasma inositol changed with exogenous insulin infusions. Additionally, maternal insulin infusion resulted in lower fetal sorbitol and fructose (P < 0.01).

CONCLUSIONS

Chronically decreased glucose supply to the fetus as well as fetal hyperinsulinemia both reduce fetal non-glucose carbohydrates. Given the role of these carbohydrates in protein glycosylation and lipid production, more research on their metabolism in pregnancies complicated by abnormal glucose metabolism is clearly warranted.

Pharmacokinetics and safety of a single intravenous dose of myo-inositol in preterm infants of 23-29 wk

BACKGROUND

Myo-inositol given to preterm infants with respiratory distress has reduced death, increased survival without bronchopulmonary dysplasia, and reduced severe retinopathy of prematurity in two randomized trials. Pharmacokinetic (PK) studies in extremely preterm infants are needed before efficacy trials.

METHODS

Infants born in 23-29 wk of gestation were randomized to a single intravenous (i.v.) dose of inositol at 60 or 120 mg/kg or placebo. Over 96 h, serum levels (sparse sampling population PK) and urine inositol excretion were determined. Population PK models were fit using a nonlinear mixed-effects approach. Safety outcomes were recorded.

RESULTS

A single-compartment model that included factors for endogenous inositol production, allometric size based on weight, gestational age strata, and creatinine clearance fit the data best. The central volume of distribution was 0.5115 l/kg, the clearance was 0.0679 l/kg/h, endogenous production was 2.67 mg/kg/h, and the half-life was 5.22 h when modeled without the covariates. During the first 12 h, renal inositol excretion quadrupled in the 120 mg/kg group, returning to near-baseline value after 48 h. There was no diuretic side effect. No significant differences in adverse events occurred among the three groups (P > 0.05).

CONCLUSION

A single-compartment model accounting for endogenous production satisfactorily described the PK of i.v. inositol.

Human breast milk sugars and polyols over the first 10 puerperium days

OBJECTIVE

The transition from colostrum to mature breast milk during early puerperium is associated with significant concentration changes of numerous compounds. However, it is not known whether the free sugars, aminohexoses, and polyols are affected. Therefore, in this study, we aimed to determine their concentrations in human colostrum and milk during the first 10 days postpartum.

METHODS

This prospective longitudinal study in a sample of normal consecutive obstetric patients was conducted as a collaboration between two academic centers-Polish and American. Participants were 13 women after uncomplicated pregnancy and delivery at term of a singleton, appropriate-for-gestational-age fetus. Lactose, galactose, glucose, mannose, galactosamine, glucosamine, glycerol, and myo-inositol concentrations were measured using high performance liquid chromatography.

RESULTS

During the first 3 days postpartum, the concentrations of lactose and glucose increased significantly (P < 0.001), to steady-state values thereafter. In contrast, the concentrations of myo-inositol and glycerol decreased significantly (P < 0.001) over the first 4 days, to reach relatively low stable values. ANOVA analysis indicated that the postpartum day at which early changes ceased to be significantly different from their plateau values was Day 4. myo-Inositol concentrations were significantly higher (P = 0.022) in multiparas than in primiparas.

CONCLUSIONS

The colostrum-to-milk transition is associated with significant changes in concentrations of free sugars and polyols, changes which are completed by the fourth postpartum day. Parity influences the concentrations of some compounds in the breast milk.

Transplacental supply of mannose and inositol in uncomplicated pregnancies using stable isotopes

OBJECTIVE

The aim of this study was to determine relative contributions of transplacental flux vs. fetal production for inositol and mannose in normal term pregnancies.

STUDY DESIGN

Seven term uncomplicated pregnancies undergoing cesarean section were infused with (13)C- and (2)H-labeled isotopes of glucose, inositol, and mannose until a steady state was achieved. Maternal and fetal concentrations of labeled and unlabeled glucose, mannose, and inositol were measured using gas chromatography/mass spectroscopy. The fetomaternal molar percentage excess ratio was calculated for each glucose, mannose, and inositol.

RESULTS

The fetomaternal molar percentage excess ratio of mannose in the fetal artery (F(artery)/M) was 0.99 [97.5% confidence interval (CI), 0.91-1.07] and in the fetal vein (F(vein)/M), 1.02 (97.5% CI, 0.95-1.10). Both were not significantly different from 1.0, consistent with transplacental supply. The fetomaternal ratios for glucose were similar to mannose (fetal artery, 0.95; 97.5% CI, 0.84-1.15; and fetal vein, 0.96; 97.5% CI, 0.85-1.07). The fetomaternal ratio for inositol was significantly less than 1.0 (fetal artery, 0.08; 97.5% CI, 0.05-0.12; fetal vein, 0.12; 97.5% CI, 0.06-0.18), indicating little transplacental flux and significant fetal production.

CONCLUSION

In normal term pregnancies, fetal mannose and glucose concentrations are dependent upon maternal transplacental supply. Fetal inositol is not dependent upon transplacental supply.

Inositol-trisphosphate reduces alveolar apoptosis and pulmonary edema in neonatal lung injury

D-myo-inositol-1,2,6-trisphosphate (IP3) is an isomer of the naturally occurring second messenger D-myo-inositol-1,4,5-trisphosphate, and exerts anti-inflammatory and antiedematous effects in the lung. Myo-inositol (Inos) is a component of IP3, and is thought to play an important role in the prevention of neonatal pulmonary diseases such as bronchopulmonary dysplasia and neonatal acute lung injury (nALI). Inflammatory lung diseases are characterized by augmented acid sphingomyelinase (aSMase) activity leading to ceramide production, a pathway that promotes increased vascular permeability, apoptosis, and surfactant alterations. A novel, clinically relevant triple-hit model of nALI was developed, consisting of repeated airway lavage, injurious ventilation, and lipopolysaccharide instillation into the airways, every 24 hours. Thirty-five piglets were randomized to one of four treatment protocols: control (no intervention), surfactant alone, surfactant + Inos, and surfactant + IP3. After 72 hours of mechanical ventilation, lungs were excised from the thorax for subsequent analyses. Clinically, oxygenation and ventilation improved, and extravascular lung water decreased significantly with the S + IP3 intervention. In pulmonary tissue, we observed decreased aSMase activity and ceramide concentrations, decreased caspase-8 concentrations, reduced alveolar epithelial apoptosis, the reduced expression of interleukin-6, transforming growth factor-β1, and amphiregulin (an epithelial growth factor), reduced migration of blood-borne cells and particularly of CD14(+)/18(+) cells (macrophages) into the airspaces, and lower surfactant surface tensions in S + IP3-treated but not in S + Inos-treated piglets. We conclude that the admixture of IP3 to surfactant, but not of Inos, improves gas exchange and edema in our nALI model by the suppression of the governing enzyme aSMase, and that this treatment deserves clinical evaluation.

High-precision mass spectrometric analysis using stable isotopes in studies of children

The use of stable isotopes combined with mass spectrometry (MS) provides insight into metabolic processes within the body. Herein, an overview on the relevance of stable isotope methodology in pediatric research is presented. Applications for the use of stable isotopes with MS cover carbohydrate, fat, and amino acid metabolism as well as body composition, energy expenditure, and the synthesis of specific peptides and proteins, such as glutathione and albumin. The main focus of these studies is on the interactions between nutrients and the endogenous metabolism within the body and how these factors affect the health of a growing infant. Considering that the early imprinting of metabolic processes hugely impacts metabolism (and thus functional outcome) later in life, research in this area is important and is advancing rapidly. The major fluxes on a metabolic level are the synthesis and breakdown rates. They can be quantified using kinetic tracer analysis and mathematical modeling. Organic MS and isotope ratio mass spectrometry (IRMS) are the two most mature techniques for the isotopic analysis of compounds. Introduction of the samples is usually done by coupling gas chromatography (GC) to either IRMS or MS because it is the most robust technique for specific isotopic analysis of volatile compounds. In addition, liquid chromatography (LC) is now being used more often as a tool for sample introduction of both volatile and non-volatile compounds into IRMS or MS for (13)C isotopic analyses at natural abundances and for (13)C-labeled enriched compounds. The availability of samples is often limited in pediatric patients. Therefore, sample size restriction is important when developing new methods. Also, the availability of stable isotope-labeled substrates is necessary for measurements of the kinetics and concentrations in metabolic studies, which can be a limiting factor. During the last decade, the availability of these substrates has increased. Furthermore, improvements in the accuracy, precision, and sensitivity of existing techniques (such as GC/IRMS) and the development of new techniques (such as LC/IRMS) have opened up new avenues for tackling these limitations.

PCR screening and sequence analysis of iol clusters in Lactobacillus casei strains isolated from koumiss

The iol cluster (consisting of genes involved in myo-inositol utilization) was investigated in Lactobacillus casei strains isolated from koumiss. Ten strains were tested for the presence of iol cluster by PCR screening; three strains encoded this cluster. Full-sequencing procedure was conducted; the iol cluster was identical to that of L. casei BL23 (GenBank access. no. FM177140) except for an upstream transposase. The iol cluster is not a common feature for L. casei strains isolated from koumiss.