Development of a Pure Certified Reference Material of D-Mannitol

A new certified reference material (CRM) of D-mannitol (GBW(E) 100681) has been developed in this study. We describe the preparation, structure determination, characterization, homogeneity study, stability study, as well as uncertainty estimation. The main component was 99.91% ± 0.01%. The moisture content of the candidate CRM was 0.036% ± 0.002%, as measured by Karl Fischer titration. The nonvolatile and volatile impurities in the candidate CRM were all much less than 0.01%, which was determined by the ICP-MS and headspace GC-FID methods, respectively. The purity of the D-mannitol CRM was 99.9% ± 1.1% (k = 2), as measured by the two independent approaches involving the mass balance method (MB) and quantitative nuclear magnetic resonance technique (qNMR). The D-mannitol CRM was stable during the monitoring period for each temperature. It is stable for up to 48 months at room temperature and 28 days at 50 °C. The uncertainty was evaluated by combining the contributions from characterization, homogeneity, and stability. The developed D-mannitol CRM would effectively support method validation and proficiency testing, as well as effectively guarantee the accuracy, reliability, and comparability of results.

Severe, short-term sleep restriction reduces gut microbiota community richness but does not alter intestinal permeability in healthy young men

Sleep restriction alters gut microbiota composition and intestinal barrier function in rodents, but whether similar effects occur in humans is unclear. This study aimed to determine the effects of severe, short-term sleep restriction on gut microbiota composition and intestinal permeability in healthy adults. Fecal microbiota composition, measured by 16S rRNA sequencing, and intestinal permeability were measured in 19 healthy men (mean ± SD; BMI 24.4 ± 2.3 kg/m², 20 ± 2 years) undergoing three consecutive nights of adequate sleep (AS; 7-9 h sleep/night) and restricted sleep (SR; 2 h sleep/night) in random order with controlled diet and physical activity. α-diversity measured by amplicon sequencing variant (ASV) richness was 21% lower during SR compared to AS (P = 0.03), but α-diversity measured by Shannon and Simpson indexes did not differ between conditions. Relative abundance of a single ASV within the family Ruminococcaceae was the only differentially abundant taxon (q = 0.20). No between-condition differences in intestinal permeability or β-diversity were observed. Findings indicated that severe, short-term sleep restriction reduced richness of the gut microbiota but otherwise minimally impacted community composition and did not affect intestinal permeability in healthy young men.

The Fecal Metabolome Links Diet Composition, Foacidic positive ion conditions, chromatographicallyod Processing, and the Gut Microbiota to Gastrointestinal Health in a Randomized Trial of Adults Consuming a Processed Diet

BACKGROUND

Food processing alters diet digestibility and composition, thereby influencing interactions between host biology, diet, and the gut microbiota. The fecal metabolome offers insight into those relations by providing a readout of diet-microbiota interactions impacting host health.

OBJECTIVES

The aims were to determine the effects of consuming a processed diet on the fecal metabolome and to explore relations between changes in the fecal metabolome with fecal microbiota composition and gastrointestinal health markers.

METHODS

This was a secondary analysis of a randomized controlled trial wherein healthy adults [94% male; 18-61 y; BMI (kg/m²): 26 ± 3] consumed their usual diet [control (CON), n = 27] or a Meal, Ready-to-Eat^TM (Ameriqual Packaging) military ration diet composed of processed, shelf-stable, ready-to-eat items for 21 d (MRE; n = 27). Fecal metabolite profiles, fecal microbiota composition, biomarkers of intestinal barrier function, and gastrointestinal symptoms were measured before and after the intervention. Between-group differences and associations were assessed using nonparametric t tests, partial least-squares discriminant analysis, correlation, and redundancy analysis.

RESULTS

Fecal concentrations of multiple dipeptides [Mann-Whitney effect size (ES) = 0.27-0.50] and long-chain SFAs (ES = 0.35-0.58) increased, whereas plant-derived compounds (ES = 0.31-0.60) decreased in MRE versus CON (P < 0.05; q < 0.20). Changes in dipeptides correlated positively with changes in fecal concentrations of Maillard-reaction products (ρ = 0.29-0.70; P < 0.05) and inversely with changes in serum prealbumin (ρ = -0.30 to -0.48; P ≤ 0.03). Multiple bile acids, coffee and caffeine metabolites, and plant-derived compounds were associated with both fecal microbiota composition and gastrointestinal health markers, with changes in fecal microbiota composition explaining 26% of the variability within changes in gastrointestinal health-associated fecal metabolites (P = 0.001).

CONCLUSIONS

Changes in the fecal metabolomes of adults consuming a Meal, Ready-to-Eat^TM diet implicate interactions between diet composition, diet digestibility, and the gut microbiota as contributing to variability within gastrointestinal responses to the diet. Findings underscore the need to consider both food processing and nutrient composition when investigating the impact of diet-gut microbiota interactions on health outcomes. This trial was registered at www.

CLINICALTRIALS

gov as NCT02423551.

A Simple, Robust, and Convenient HPLC Assay for Urinary Lactulose and Mannitol in the Dual Sugar Absorption Test

Background: Heterogeneous laborious analytical methodologies for the determination of urinary lactulose and mannitol limit their utility in intestinal permeability testing. Methods: We developed an assay using a Shimadzu HPLC system, an Aminex HPX87C column, and refractive index detection. The test was calibrated using a series of dilutions from standard stock solutions of lactulose and mannitol ‘spiked’ into urine samples. The utility to quantify urinary excretion during the dual sugar absorption test over 6 h was also determined. Results: Lactulose and mannitol were eluted isocratically at 5.7 and 10.1 min, respectively, with water as a mobile phase at a flow rate of 0.3 mL min⁻¹, 858 psi, 60 °C. The calibration curves for both sugars were linear up to 500 µg mL⁻¹ with a limit of detection in standard solutions at 4 µg mL⁻¹ and in ‘spiked’ urine samples at 15 µg mL⁻¹. The intra-assay and inter-assay CVs were between 2.0–5.1% and 2.0–5.1% for lactulose and 2.5–4.4% and 2.8–3.9% for mannitol. The urinary profiles of the 6 h absorption of lactulose and mannitol showed similar peak-retention times to standard solutions and were well-resolved at 5.9 and 10.4 min, respectively. Conclusions: The assay was easy to automate, using commonly available equipment and convenient requiring no prior laborious sample derivatization. The simplicity, reproducibility, and robustness of this assay facilitates its use in routine clinical settings for the quantification of intestinal permeability.

A case for improved assessment of gut permeability: a meta-analysis quantifying the lactulose:mannitol ratio in coeliac and Crohn's disease

BACKGROUND

A widely used method in assessing small bowel permeability is the lactulose:mannitol test, where the lactulose:mannitol ratio (LMR) is measured. However, there is discrepancy in how the test is conducted and in the values of LMR obtained across studies. This meta-analysis aims to determine LMR in healthy subjects, coeliac and Crohn's disease.

METHODS

A literature search was performed using PRISMA guidance to identify studies assessing LMR in coeliac or Crohn's disease. 19 studies included in the meta-analysis measured gut permeability in coeliac disease, 17 studies in Crohn's disease. Outcomes of interest were LMR values and comparisons of standard mean difference (SMD) and weighted mean difference (WMD) in healthy controls, inactive Crohn's, active Crohn's, treated coeliac and untreated coeliac. Pooled estimates of differences in LMR were calculated using the random effects model.

RESULTS

Pooled LMR in healthy controls was 0.014 (95% CI: 0.006-0.022) while pooled LMRs in untreated and treated coeliac were 0.133 (95% CI: 0.089-0.178) and 0.037 (95% CI: 0.019-0.055). In active and inactive Crohn's disease, pooled LMRs were 0.093 (95% CI: 0.031-0.156) and 0.028 (95% CI: 0.015-0.041). Significant differences were observed in LMR between: (1) healthy controls and treated coeliacs (SMD = 0.409 95% CI 0.034 to 0.783, p = 0.032), (2) healthy controls and untreated coeliacs (SMD = 1.362 95% CI: 0.740 to 1.984, p < 0.001), (3) treated coeliacs and untreated coeliacs (SMD = 0.722 95% CI: 0.286 to 1.157, p = 0.001), (4) healthy controls and inactive Crohn's (SMD = 1.265 95% CI: 0.845 to 1.686, p < 0.001), (5) healthy controls and active Crohn's (SMD = 2.868 95% CI: 2.112 to 3.623, p < 0.001), and (6) active Crohn's and inactive Crohn's (SMD = 1.429 (95% CI: 0.580 to 2.278, p = 0.001). High heterogeneity was observed, which was attributed to variability in protocols used across different studies.

CONCLUSION

The use of gut permeability measurements in screening and monitoring of coeliac and Crohn's disease is promising. LMR is useful in performing this function with significant limitations. More robust alternative tests with higher degrees of clinical evidence are needed if measurements of gut permeability are to find widespread clinical use.

Intestinal Permeability and Circulating CD161+CCR6+CD8+T Cells in Patients With Relapsing-Remitting Multiple Sclerosis Treated With Dimethylfumarate

Background: The changes of the gut-brain axis have been recently recognized as important components in multiple sclerosis (MS) pathogenesis.

Objectives: To evaluate the effects of DMF on intestinal barrier permeability and mucosal immune responses.

Methods: We investigated intestinal permeability (IP) and circulating CD161+CCR6+CD8+T cells in 25 patients with MS, who met eligibility criteria for dimethyl-fumarate (DMF) treatment. These data, together with clinical/MRI parameters, were studied at three time-points: baseline (before therapy), after one (T1) and 9 months (T2) of treatment.

Results: At baseline 16 patients (64%) showed altered IP, while 14 cases (56%) showed active MRI. During DMF therapy we found the expected decrease of disease activity at MRI compared to T0 (6/25 at T1, p = 0.035 and 3/25 at T2, p < 0.00), and a reduction in the percentage of CD161+CCR6+CD8+ T cells (16/23 at T2; p < 0.001). The effects of DMF on gut barrier alterations was variable, without a clear longitudinal pattern, while we found significant relationships between IP changes and drop of MRI activity (p = 0.04) and circulating CD161+CCr6+CD8+ T cells (p = 0.023).

Conclusions: The gut barrier is frequently altered in MS, and the CD161+ CCR6+CD8+ T cell-subset shows dynamics which correlate with disease course and therapy.

Serum zonulin and claudin-5 levels in children with obsessive-compulsive disorder

Background: Obsessive-compulsive disorder (OCD), a chronically debilitating neuropsychiatric disorder, is characterized by distinctive and recurrent obsessions and/or compulsions. An increasing number of evidence indicates that sophisticated interactions between different neurobiological factors play a part in OCD etiology, but the certain underlying mechanisms are still mainly unknown. The present research aimed to explore whether the concentrations of serum zonulin and claudin-5 vary between OCD patients and healthy controls. The present research also intended to explore whether there is an association between zonulin and claudin-5 concentrations and OCD severity.Methods: Twenty-four (13 boys and 11 girls) OCD patients and 24 (13 boys and 11 girls) healthy controls were included in this study. The clinical severity of the OCD symptoms was evaluated by the Children's Yale-Brown Obsessive-Compulsive Scale and the Maudsley Obsessive-Compulsive Inventory. Participants also filled out the Revised Child Anxiety and Depression Scales-Child Version to determine the anxiety and depression levels of the children. Venous blood samples were collected, and serum zonulin and claudin-5 levels were measured.Results: Serum claudin-5 levels were found to be significantly higher in OCD patient whereas serum zonulin levels were not significantly different between the groups.Conclusions: Taken together with our results, our study suggests that dysregulation of the blood-brain barrier, especially claudin-5, may be involved in the etiology of OCD.

Rapid HPLC method for monitoring of lactulose production with a high yield

An HPLC method suitable for rapid monitoring of lactulose production by isomerization from lactose was developed. The separation of lactose and lactulose under hydrophilic interaction liquid chromatography (HILIC) mode was achieved with resolution 1.5 within 5 min. Since isocratic elution was used, there is no extra time necessary for the column equilibration. Application of the method was illustrated on monitoring lactulose isomerization with catalysis of sodium hydroxide in the presence of sodium tetraborate at 70 °C (pH = 11). The conversion yield obtained for lactulose was 86%, and corresponding purity 76%. For the first time, a polyhydroxy stationary phase for separation of lactose and lactulose is reported.

A diet of U.S. military food rations alters gut microbiota composition and does not increase intestinal permeability

Interactions between gut microbes and dietary components modulate intestinal permeability (IP) and inflammation. Recent studies have reported altered fecal microbiota composition together with increased IP and inflammation in individuals consuming military food rations in austere environments, but could not isolate effects of the diet from environmental factors. To determine how the U.S. Meal, Ready-to-Eat food ration affects fecal microbiota composition, IP and inflammation, 60 adults (95% male,18-61 years) were randomized to consume their usual ad libitum diet for 31 days (CON) or a strictly controlled Meal, Ready-to-Eat-only diet for 21 days followed by their usual diet for 10 days (MRE). In both groups, fecal microbiota composition was measured before, during (INT, days 1-21) and after the intervention period. IP and inflammation [high-sensitivity C-reactive protein (hsCRP)] were measured on days 0, 10, 21 and 31. Longitudinal changes in fecal microbiota composition differed between groups (P=.005), and fecal samples collected from MRE during INT were identified with 88% accuracy using random forest models. The genera making the strongest contribution to that prediction accuracy included multiple lactic acid bacteria (Lactobacillus, Lactococcus, Leuconostoc), which demonstrated lower relative abundance in MRE, and several genera known to dominate the ileal microbiota (Streptococcus, Veillonella, Clostridium), the latter two demonstrating higher relative abundance in MRE. IP and hsCRP were both lower (34% and 41%, respectively) in MRE relative to CON on day 21 (P<.05) but did not differ otherwise. Findings demonstrate that a Meal, Ready-to-Eat ration diet alters fecal microbiota composition and does not increase IP or inflammation.

Local gastric RAAS inhibition improves gastric microvascular perfusion in dogs

During circulatory shock, gastrointestinal microcirculation is impaired, especially via activation of the renin-angiotensin-aldosterone system. Therefore, inhibition of the renin-angiotensin-aldosterone system might be beneficial in maintaining splanchnic microcirculation. The aim of this study was to analyze whether locally applied losartan influences gastric mucosal perfusion (µflow, µvelo) and oxygenation (µHbO2) without systemic hemodynamic changes. In repetitive experiments six anesthetized dogs received 30 mg losartan topically on the oral and gastric mucosa during normovolemia and hemorrhage (-20% blood volume). Microcirculatory variables were measured with reflectance spectrometry, laser Doppler flowmetry and incident dark field imaging. Transpulmonary thermodilution and pulse contour analysis were used to measure systemic hemodynamic variables. Gastric barrier function was assessed via differential absorption of inert sugars. During normovolemia, losartan increased gastric µflow from 99 ± 6 aU to 147 ± 17 aU and µvelo from 17 ± 1 aU to 19 ± 1 aU. During hemorrhage, losartan did not improve µflow. µvelo decreased from 17 ± 1 aU to 14 ± 1 aU in the control group. Application of losartan did not significantly alter µvelo (16 ± 1 aU) compared to the control group and to baseline levels (17 ± 1 aU). No effects of topical losartan on macrohemodynamic variables or microcirculatory oxygenation were detected. Gastric microcirculatory perfusion is at least partly regulated by local angiotensin receptors. Topical application of losartan improves local perfusion via vasodilation without significant effects on systemic hemodynamics. During mild hemorrhage losartan had minor effects on regional perfusion, probably because of a pronounced upstream vasoconstriction.

Associations between the gut microbiota and host responses to high altitude

Hypobaric hypoxia and dietary protein and fat intakes have been independently associated with an altered gastrointestinal (GI) environment and gut microbiota, but little is known regarding host-gut microbiota interactions at high altitude (HA) and the impact of diet macronutrient composition. This study aimed to determine the effect of dietary protein:fat ratio manipulation on the gut microbiota and GI barrier function during weight loss at high altitude (HA) and to identify associations between the gut microbiota and host responses to HA. Following sea-level (SL) testing, 17 healthy males were transported to HA (4,300 m) and randomly assigned to consume provided standard protein (SP; 1.1 g·kg^-1·day^-1, 39% fat) or higher protein (HP; 2.1 g·kg^-1·day^-1, 23% fat) carbohydrate-matched hypocaloric diets for 22 days. Fecal microbiota composition and metabolites, GI barrier function, GI symptoms, and acute mountain sickness (AMS) severity were measured. Macronutrient intake did not impact fecal microbiota composition, had only transient effects on microbiota metabolites, and had no effect on increases in small intestinal permeability, GI symptoms, and inflammation observed at HA. AMS severity was also unaffected by diet but in exploratory analyses was associated with higher SL-relative abundance of Prevotella, a known driver of interindividual variability in human gut microbiota composition, and greater microbiota diversity after AMS onset. Findings suggest that the gut microbiota may contribute to variability in host responses to HA independent of the dietary protein:fat ratio but should be considered preliminary and hypothesis generating due to the small sample size and exploratory nature of analyses associating the fecal microbiota and host responses to HA. NEW & NOTEWORTHY This study is the first to examine interactions among diet, the gut microbiota, and host responses to weight loss at high altitude (HA). Observed associations among the gut microbiota, weight loss at HA, and acute mountain sickness provide evidence that the microbiota may contribute to variability in host responses to HA. In contrast, dietary protein:fat ratio had only minimal, transient effects on gut microbiota composition and bacterial metabolites which were likely not of clinical consequence.

Probiotics in cystic fibrosis patients: A double blind crossover placebo controlled study: Pilot study from the ESPGHAN Working Group on Pancreas/CF

BACKGROUND

A potential positive effect of probiotics in cystic fibrosis (CF) on fecal calprotectin (FCP), pulmonary exacerbations and weight has been described in small controlled trials.

METHODS

A double-blind multicenter cross-over study (2 × 4 m) was performed looking at abdominal pain, nutritional status, pulmonary function, pulmonary exacerbation, FCP and lactulose/mannitol gut permeability test. Patients kept a diary with daily scoring of abdominal pain, stool frequency and consistency as well as treatment changes.

RESULTS

31 CF patients entered the study of which 25 finished it. At start patients aged 9.3yrs (6.9-12.2), had a median BMI z-score of -0.5 (-1.5-0.08), height z-score of -0.4 (-1.1-0.05) and FEV1% of 100% (87.2-106.6). Median FCP at start was 61 μg/g (17-108) and gut permeability 0.079 (0.051-0.122). No significant changes were observed in the clinical parameters (BMI, FEV1%, abdominal pain, exacerbations). Despite being frequently abnormal (17/28 (61%) >50 mg/kg), FCP did not change significantly with probiotics. The proportion of patients with normal permeability was 8% during placebo and 32% during probiotic treatment (p = 0.031). FCP correlated to BMI z-score (p = 0.043) and gut permeability to abdominal pain (p = 0.015). The microbiome revealed a high predominance of Actinobacteria and Proteobacteriae. Probiotic supplementation did not result in a shift at the phylum nor at phylogenetic level.

CONCLUSION

Normalization of gut permeability was observed in 13% of patients during probiotic treatment. However, none of the previously described effects could be confirmed.

Intestinal Permeability in Relapsing-Remitting Multiple Sclerosis

Changes of intestinal permeability (IP) have been extensively investigated in inflammatory bowel diseases (IBD) and celiac disease (CD), underpinned by a known unbalance between microbiota, IP and immune responses in the gut. Recently the influence of IP on brain function has greatly been appreciated. Previous works showed an increased IP that preceded experimental autoimmune encephalomyelitis development and worsened during disease with disruption of TJ. Moreover, studying co-morbidity between Crohn's disease and MS, a report described increased IP in a minority of cases with MS. In a recent work we found that an alteration of IP is a relatively frequent event in relapsing-remitting MS, with a possible genetic influence on the determinants of IP changes (as inferable from data on twins); IP changes included a deficit of the active mechanism of absorption from intestinal lumen. The results led us to hypothesize that gut may contribute to the development of MS, as suggested by another previous work of our group: a population of CD8+CD161high T cells, belonging to the mucosal-associated invariant T (MAIT) cells, a gut- and liver-homing subset, proved to be of relevance for MS pathogenesis. We eventually suggest future lines of research on IP in MS: studies on IP changes in patients under first-line oral drugs may result useful to improve their therapeutic index; correlating IP and microbiota changes, or IP and blood-brain barrier changes may help clarify disease pathogenesis; exploiting the IP data to disclose co-morbidities in MS, especially with CD and IBD, may be important for patient care.

Changes in intestinal microbiota composition and metabolism coincide with increased intestinal permeability in young adults under prolonged physiological stress

The magnitude, temporal dynamics, and physiological effects of intestinal microbiome responses to physiological stress are poorly characterized. This study used a systems biology approach and a multiple-stressor military training environment to determine the effects of physiological stress on intestinal microbiota composition and metabolic activity, as well as intestinal permeability (IP). Soldiers (n = 73) were provided three rations per day with or without protein- or carbohydrate-based supplements during a 4-day cross-country ski-march (STRESS). IP was measured before and during STRESS. Blood and stool samples were collected before and after STRESS to measure inflammation, stool microbiota, and stool and plasma global metabolite profiles. IP increased 62 ± 57% (mean ± SD, P < 0.001) during STRESS independent of diet group and was associated with increased inflammation. Intestinal microbiota responses were characterized by increased α-diversity and changes in the relative abundance of >50% of identified genera, including increased abundance of less dominant taxa at the expense of more dominant taxa such as Bacteroides Changes in intestinal microbiota composition were linked to 23% of metabolites that were significantly altered in stool after STRESS. Together, pre-STRESS Actinobacteria relative abundance and changes in serum IL-6 and stool cysteine concentrations accounted for 84% of the variability in the change in IP. Findings demonstrate that a multiple-stressor military training environment induced increases in IP that were associated with alterations in markers of inflammation and with intestinal microbiota composition and metabolism. Associations between IP, the pre-STRESS microbiota, and microbiota metabolites suggest that targeting the intestinal microbiota could provide novel strategies for preserving IP during physiological stress.NEW & NOTEWORTHY Military training, a unique model for studying temporal dynamics of intestinal barrier and intestinal microbiota responses to stress, resulted in increased intestinal permeability concomitant with changes in intestinal microbiota composition and metabolism. Prestress intestinal microbiota composition and changes in fecal concentrations of metabolites linked to the microbiota were associated with increased intestinal permeability. Findings suggest that targeting the intestinal microbiota could provide novel strategies for mitigating increases in intestinal permeability during stress.

Validation of an LC-MS/MS Method for Urinary Lactulose and Mannitol Quantification: Results in Patients with Irritable Bowel Syndrome

Aim. Lactulose/mannitol ratio is used to assess intestinal barrier function. Aim of this work was to develop a robust and rapid method for the analysis of lactulose and mannitol in urine by liquid chromatography coupled to tandem mass spectrometry. Lactulose/mannitol ratio has been measured in pediatric patients suffering from irritable bowel syndrome. Methods. Calibration curves and raffinose, used as internal standard, were prepared in water : acetonitrile 20 : 80. Fifty μL of urine sample was added to 450 μL of internal standard solution. The chromatographic separation was performed using a Luna NH2 column operating at a flow rate of 200 μL/min and eluted with a linear gradient from 20% to 80% water in acetonitrile. Total run time is 9 minutes. The mass spectrometry operates in electrospray negative mode. Method was fully validated according to European Medicine Agency guidelines. Results and Conclusions. Linearity ranged from 10 to 1000 mg/L for mannitol and 2.5 to 1000 mg/L for lactulose. Imprecision in intra- and interassay was lower than 15% for both analytes. Accuracy was higher than 85%. Lactulose/mannitol ratio in pediatric patients is significantly higher than that measured in controls. The presented method, rapid and sensitive, is suitable in a clinical laboratory.

Association between intestinal permeability and faecal microbiota composition in Italian children with beta cell autoimmunity at risk for type 1 diabetes

BACKGROUND

Pancreatic organ-specific autoimmunity in subjects at risk for type 1 diabetes (T1D) is associated with increased intestinal permeability and an aberrant gut microbiota, but these factors have not yet been simultaneously investigated in the same subjects. Thus, the aim of this study was to assess both intestinal permeability and gut microbiota composition in an Italian sample of children at risk for T1D.

METHODS

Ten Italian children with beta cell autoimmunity at risk for T1D and 10 healthy children were involved in a case-control study. The lactulose/mannitol test was used to assess intestinal permeability. Analysis of microbiota composition was performed using polymerase chain reaction followed by denaturing gradient gel electrophoresis, based on the 16S rRNA gene.

RESULTS

Intestinal permeability was significantly higher in children at risk for T1D than in healthy controls. Moreover, the gut microbiota of the former differed from that of the latter group: Three microorganisms were detected - Dialister invisus, Gemella sanguinis and Bifidobacterium longum - in association with the pre-pathologic state.

CONCLUSIONS

The results of this study validated the hypothesis that increased intestinal permeability together with differences in microbiota composition are contemporaneously associated with the pre-pathological condition of T1D in a sample of Italian children. Further studies are necessary to confirm the microbial markers identified in this sample of children as well as to clarify the involvement of microbiota modifications in the mechanisms leading to increased permeability and the autoimmune mechanisms that promote diabetes onset. Copyright © 2016 John Wiley & Sons, Ltd.

Development and application of novelty pretreatment method for the concurrent quantitation of eleven water-soluble B vitamins in ultrafiltrates after renal replacement therapy

Continous renal replacement therapy (CRRT) is particularly recommended for septic shock patients in intensive care units. The CRRT technique used most frequently is high volume continuous veno-venous haemofiltration. It provides a high rate of clearance of uremic toxins and inflammatory cytokines. However, it should also be taken into account that substances important for homeostasis may be concurrently unintentionally removed. Accordingly, water-soluble vitamins can be removed during continuous renal replacement therapy, and the estimate of the loss is critical to ensure appropriate supplementation. The aim of this work was to develop a simple methodology for a purification step prior to the LC-MS/MS determination of water-soluble vitamins in ultrafiltrate samples. For this purpose, two types of resin and a mix of resins were used as sorbents for the purification step. Moreover, parameters such as the amount of resin and the extraction time were optimized. The LC-MS/MS method was developed and validated for final determination of 11 vitamins. The results demonstrated the high purification capability of DEAE Sephadex resin with recoveries between 65 and 101% for water-soluble vitamins from ultrafiltrate samples. An optimized method was applied to assess the loss of B-group vitamins in patients after 24h of renal replacement therapy. The loss of vitamins B2, B6 pyridoxamine, B6 pyridoxal, B7, B1, and B5 in ultrafiltrates was similar in all patients. In the native ultrafiltrates, vitamins B6 pyridoxine, B9 and B12 were not detected.

Altered intestinal permeability in patients with relapsing-remitting multiple sclerosis: A pilot study

BACKGROUND

Alterations of intestinal permeability (IP) may contribute to the pathophysiology of immune-mediated diseases.

OBJECTIVE

We investigated the possible association between IP changes and multiple sclerosis (MS).

METHODS

We studied 22 patients with relapsing-remitting multiple sclerosis (RRMS) and 18 age- and sex-matched healthy donors (HDs), including five twin pairs (one concordant, and four discordant for disease). Measurement of lactulose (L) and mannitol (M; two non-metabolized sugars) levels in urine samples, after an oral load, allowed to quantify gut dysfunction.

RESULTS

The proportion of participants with increased IP was significantly higher in patients than in HDs (16/22 (73%) versus 5/18 (28%); p = 0.001). Accordingly, the L/M urinary ratio showed significantly higher values in patients than in controls ( p = 0.0284). Urinary mannitol concentration was significantly lower in patients than in controls ( p = 0.022), suggesting a deficit of absorption from intestinal lumen. Such changes did not appear related to patients' clinical-radiological features.

CONCLUSION

The relatively high proportion of IP changes in RR-MS patients seems to confirm our work hypothesis and warrants more work to confirm the result on a larger sample, and to understand the implications for related immunological disturbances and intestinal microbiota alterations. Our finding may also have relevance for oral treatments, recently introduced in clinical practice.

Intestinal lesions are associated with altered intestinal microbiome and are more frequent in children and young adults with cystic fibrosis and cirrhosis

BACKGROUND AND AIMS

Cirrhosis (CIR) occurs in 5-7% of cystic fibrosis (CF) patients. We hypothesized that alterations in intestinal function in CF contribute to the development of CIR.

AIMS

Determine the frequency of macroscopic intestinal lesions, intestinal inflammation, intestinal permeability and characterize fecal microbiome in CF CIR subjects and CF subjects with no liver disease (CFnoLIV).

METHODS

11 subjects with CFCIR (6 M, 12.8 yrs ± 3.8) and 19 matched with CFnoLIV (10 M, 12.6 yrs ± 3.4) underwent small bowel capsule endoscopy, intestinal permeability testing by urinary lactulose: mannitol excretion ratio, fecal calprotectin determination and fecal microbiome characterization.

RESULTS

CFCIR and CFnoLIV did not differ in key demographics or CF complications. CFCIR had higher GGT (59±51 U/L vs 17±4 p = 0.02) and lower platelet count (187±126 vs 283±60 p = 0.04) and weight (-0.86 ± 1.0 vs 0.30 ± 0.9 p = 0.002) z scores. CFCIR had more severe intestinal mucosal lesions on capsule endoscopy (score ≥4, 4/11 vs 0/19 p = 0.01). Fecal calprotectin was similar between CFCIR and CFnoLIV (166 μg/g ±175 vs 136 ± 193 p = 0.58, nl <120). Lactulose:mannitol ratio was elevated in 27/28 subjects and was slightly lower in CFCIR vs CFnoLIV (0.08±0.02 vs 0.11±0.05, p = 0.04, nl ≤0.03). Small bowel transit time was longer in CFCIR vs CFnoLIV (195±42 min vs 167±68 p<0.001, nl 274 ± 41). Bacteroides were decreased in relative abundance in CFCIR and were associated with lower capsule endoscopy score whereas Clostridium were more abundant in CFCIR and associated with higher capsule endoscopy score.

CONCLUSIONS

CFCIR is associated with increased intestinal mucosal lesions, slower small bowel transit time and alterations in fecal microbiome. Abnormal intestinal permeability and elevated fecal calprotectin are common in all CF subjects. Disturbances in intestinal function in CF combined with changes in the microbiome may contribute to the development of hepatic fibrosis and intestinal lesions.

Circulating zonulin levels in newly diagnosed Chinese type 2 diabetes patients

AIMS

Studies suggest that type 2 diabetes mellitus is associated with increased gut permeability. Human zonulin is the only physiological mediator discovered to date that is known to regulate gut permeability reversibly by disassembling intestinal tight junctions. However, the relationship between zonulin and type 2 diabetes remains to be defined, and no Chinese population-based data were reported. The aim of this study was to investigate the association between serum zonulin levels and type 2 diabetes in a Chinese Han population.

METHODS

143 newly diagnosed type 2 diabetes patients, 124 patients with impaired glucose tolerance and 121 subjects with normal glucose tolerance were enrolled in this study. Serum zonulin was measured by ELISA.

RESULTS

Patients with type 2 diabetes had higher serum zonulin levels than impaired or normal glucose tolerant subjects. Serum zonulin correlated with body mass index, waist-to-hip ratio, triglyceride, total cholesterol, HDL-C, fasting plasma glucose, 2h plasma glucose, HbA1c, tumor necrosis factor α, interleukin 6, HOMA-IR and QUICK index using correlation analysis (p < 0.05 for all). Multivariate stepwise regression analysis showed that zonulin levels were independently associated with insulin resistance (β = 0.024, p = 0.005). In logistic regression analysis, zonulin levels were an independent predictor of type 2 diabetes (OR = 1.080, p = 0.037).

CONCLUSIONS

Serum zonulin levels are significantly elevated in newly diagnosed Chinese Type 2 diabetes patients, and are associated with dyslipidemia, inflammation and insulin resistance, indicating a potential role of zonulin in the pathophysiology of type 2 diabetes in Chinese.

Pre-clinical Crohn's disease: diagnosis, treatment and six year follow-up

Diagnosis of Crohn's disease is usually made at a symptomatic stage. However diagnosis at a pre-clinical stage might provide valuable information on etiology/pathogenesis and allow early intervention to alter its natural history. We describe here the case of a 27 year old woman who was diagnosed with Crohn's disease at a completely asymptomatic stage and followed up for more than six years. She was part of an ongoing screening study in first degree relatives of Crohn's disease patients. At diagnosis, colonoscopy showed modest inflammation and few superficial ulcerations and erosions in the ileo-cecal valve and the terminal ileum. Fecal calprotectin was only modestly elevated. Intestinal permeability was also increased. During follow-up and while still asymptomatic the patient was sequentially treated with therapeutic doses of 5-ASA, budesonide, azathioprine and infliximab in an attempt to stop disease progression. Only infliximab appeared capable of inducing profound mucosal healing-however the disease recurred several months after the medication was ceased. Over time, quantification by immunohistochemistry of a number of cell types and cytokines revealed a positive correlation between CD4-CD25-FOXP3 (Treg) cell number and inflammation, a finding potentially consistent with tissue resistance to Tregs' activity.

Bovine colostrum, training status, and gastrointestinal permeability during exercise in the heat: a placebo-controlled double-blind study

Heat stress can increase gastrointestinal permeability, allowing ingress of gram-negative bacterial fragments and thus potentially inflammation and ultimately endotoxemia. Permeability may rise with intense exercise, yet some data indicate that endotoxemia may be mitigated with bovine colostrum supplementation. Using a double-blind, randomised, placebo-controlled crossover study, we tested whether bovine colostrum (COL; 1.7 g·kg(-1)·day(-1) for 7 days) would attenuate physiological strain and aid exercise capacity in the heat, especially in untrained individuals. Seven trained men (T; peak oxygen uptake 64 ± 4 mL·kg(-1)·min(-1)) and 8 untrained men (UT, peak oxygen uptake 46 ± 4 mL·kg(-1)·min(-1)) exercised for 90 min in 30 °C (50 % relative humidity) after COL or placebo (corn flour). Exercise consisted of 15-min cycling at 50 % heart rate reserve (HRR) before and after 60 min of running (30 min at 80 % HRR then 30-min distance trial). Heart rate, blood pressure (Finometer), esophageal, and skin temperatures were recorded continuously. Gastrointestinal permeability was assessed from urine (double-sugar model, using high-performance liquid chromatography) and blood (intestinal fatty acid-binding protein, I-FABP). The T group ran ∼2.4 km (35%) further than the UT group in the distance trial, and I-FABP increased more in the T group than in the UT group, but physiological and performance outcomes were unaffected by colostrum supplementation, irrespective of fitness. Circulating pro- and anti-inflammatory cytokine concentrations were higher following exercise, but were not modulated by fitness or COL. Despite substantial thermal and cardiovascular strain incurred in environmental conditions in which exertional endotoxemia may occur, bovine colostrum supplementation had no observable benefit on the physiology or performance of either highly trained endurance athletes or untrained individuals.

Chlorogenic acid decreases intestinal permeability and increases expression of intestinal tight junction proteins in weaned rats challenged with LPS

Chlorogenic acid, a natural phenolic acid present in fruits and plants, provides beneficial effects for human health. The objectives of this study were to investigate whether chlorogenic acid (CHA) could improve the intestinal barrier integrity for weaned rats with lipopolysaccharide (LPS) challenge. Thirty-two weaned male Sprague Dawley rats (21±1 d of age; 62.26±2.73 g) were selected and randomly allotted to four treatments, including weaned rat control, LPS-challenged and chlorogenic acid (CHA) supplemented group (orally 20 mg/kg and 50 mg/kg body). Dietary supplementation with CHA decreased (P<0.05) the concentrations of urea and albumin in the serum, compared to the LPS-challenged group. The levels of IFN-γ and TNF-α were lower (P<0.05) in the jejunal and colon of weaned rats receiving CHA supplementation, in comparison with the control group. CHA supplementation increased (P<0.05) villus height and the ratio of villus height to crypt depth in the jejunal and ileal mucosae under condictions of LPS challenge. CHA supplementation decreased (P<0.05) intestinal permeability, which was indicated by the ratio of lactulose to mannitol and serum DAO activity, when compared to weaned rats with LPS challenge. Immunohistochemical analysis of tight junction proteins revealed that ZO-1 and occludin protein abundances in the jejunum and colon were increased (P<0.05) by CHA supplementation. Additionally, results of immunoblot analysis revealed that the amount of occludin in the colon was also increased (P<0.05) in CHA-supplemented rats. In conclusion, CHA decreases intestinal permeability and increases intestinal expression of tight junction proteins in weaned rats challenged with LPS.

Tissue studies in screened first-degree relatives reveal a distinct Crohn's disease phenotype

BACKGROUND

First-degree relatives of patients with Crohn's disease (CD) are at risk of developing the disease with 5% to 15% reported to be affected over time. Yet, a much greater proportion of them (>40%) shows features of "subclinical inflammation" with elevated intestinal inflammatory markers such as fecal calprotectin. The meaning of these findings is unclear in the absence of tissue data.

METHODS

Thirty-eight asymptomatic first-degree relatives of patients with CD underwent ileocolonoscopy and other tests including fecal calprotectin. All known causes of intestinal inflammation were carefully excluded. Age and gender-matched controls consisted of 10 individuals who underwent colonoscopy for other reasons. Histology was scored based on known methods.

RESULTS

Compared with controls, the relatives had significantly greater median values for fecal calprotectin and histological scores. In relatives, endoscopy identified 3 different phenotypes: (1) normal, (2) with minor lesions (aphthae or small superficial erosions), and (3) with typical CD inflammation. Based on the histological scores, the clustering analysis produced 3 corresponding highly separated clusters (61%, 26%, and 13% of the total, respectively) with divisive coefficient D = 0.94. When followed up (on the average for 53 mo), individuals in the second cluster had histological scores similar to baseline values (P = 0.12).

CONCLUSIONS

Tissue studies in first-degree relatives of patients with CD reveal 3 distinct groups: normal, with minimal inflammation, and with frank disease. The second cluster represents a novel phenotype, which does not seem to develop the disease over time. These findings explain previous observations of "subclinical inflammation" in such population.

Gut permeability in autism spectrum disorders

OBJECTIVE

To test whether gut permeability is increased in autism spectrum disorders (ASD) by evaluating gut permeability in a population-derived cohort of children with ASD compared with age- and intelligence quotient-matched controls without ASD but with special educational needs (SEN).

PATIENTS AND METHODS

One hundred thirty-three children aged 10-14 years, 103 with ASD and 30 with SEN, were given an oral test dose of mannitol and lactulose and urine collected for 6 hr. Gut permeability was assessed by measuring the urine lactulose/mannitol (L/M) recovery ratio by electrospray mass spectrometry-mass spectrometry. The ASD group was subcategorized for comparison into those without (n = 83) and with (n = 20) regression.

RESULTS

There was no significant difference in L/M recovery ratio (mean (95% confidence interval)) between the groups with ASD: 0.015 (0.013-0.018), and SEN: 0.014 (0.009-0.019), nor in lactulose, mannitol, or creatinine recovery. No significant differences were observed in any parameter for the regressed versus non-regressed ASD groups. Results were consistent with previously published normal ranges. Eleven children (9/103 = 8.7% ASD and 2/30 = 6.7% SEN) had L/M recovery ratio > 0.03 (the accepted normal range cut-off), of whom two (one ASD and one SEN) had more definitely pathological L/M recovery ratios > 0.04.

CONCLUSION

There is no statistically significant group difference in small intestine permeability in a population cohort-derived group of children with ASD compared with a control group with SEN. Of the two children (one ASD and one SEN) with an L/M recovery ratio of > 0.04, one had undiagnosed asymptomatic celiac disease (ASD) and the other (SEN) past extensive surgery for gastroschisis.

Intestinal permeability in subjects from two different race groups with diverse stone-risk profiles

It is well established that calcium oxalate stones may be caused by colonic or ileum oxalate (Ox) hyperabsorption (secondary to intestinal dysfunction). Studies have reported that increased intestinal permeability (IP) can cause hyperabsorption of nutrients culminating in passive diffusion of Ox. In South Africa, renal stones occur in the white population (W) but are extremely rare in the black population (B). Previous studies have shown that despite B having a hyperoxalurogenic diet relative to W, urinary Ox in the former is not higher. It has been suggested that different Ox handling mechanisms in the groups are the cause of this disparity. The present study was undertaken to examine whether the IP index, a reliable and accurate measure of intestinal integrity, plays a role in this anomaly. Ten healthy males from each group ingested a dual-sugar isotonic solution containing 5 g lactulose (LA) and 2 g mannitol (MA). IP was assessed by comparing the LA:MA ratio in 5 h urine samples using high performance anion exchange chromatography coupled with pulse amperometric detection to measure the concentration of each sugar. 24 h dietary intake and urine composition were also determined. LA excretion was identical in both groups (0.03 %) while MA excretion was 8.3 % in B and 11.3 % in W. IP index was 0.004 for B and 0.003 for W. It is concluded that IP is not a contributory factor in the apparent different handling of dietary Ox in B and W South Africans. It is speculated that differences in renal transporters may play a role.

Modern approach for determination of lactulose, mannitol and sucrose in human urine using HPLC-MS/MS for the studies of intestinal and upper digestive tract permeability

A new analytical procedure was described for the simultaneous determination of lactulose, mannitol and sucrose in urine, in which HILIC chromatography and tandem mass spectrometry detection are used. Sugars are orally administered for the estimation of intestinal permeability in children digestive tract. Samples were purified by dispersive solid phase extraction (d-SPE) using Amberlite MB150 resin. Raffinose was selected as an internal standard. The chosen chromatographic separation was carried out on ZIC(®)-HILIC column in 10 min at a flow rate of 0.3 mL/min, using mixture of acetonitrile (ACN) and ammonium acetate (NH(4)Ac) in water (H(2)O) as the mobile phase. Within-run precision (CV) measured at three concentrations was 1.08%, 0.32% and 0.49% for lactulose; 1.88%, 0.47% and 0.75% for mannitol, 2.95%, 1.31% and 0.6% for sucrose. Between-run CVs were 0.75%, 1.1% and 1.2% for lactulose; 1.1%, 1.02% and 1.01% for mannitol; 1.17%, 1.4% and 1.05% for sucrose. Analytical recovery of all three sugar probes was 95.06-99.92%. The detection limits were: 15.94 ng/mL for lactulose, 17.10 ng/mL for sucrose and 11.48 ng/mL for mannitol. The proposed method is rapid, simple, sensitive and suitable for the determination of intestinal permeability of the sugar derivatives in children.

Lactulose: production, purification and potential applications

Lactulose a "bifidus factor" is composed of galactose and fructose, which can be produced by the isomerization of lactose. It is a prebiotic carbohydrate which stimulates the growth of health-promoting bacteria in the gastrointestinal tract, such as bifidobacteria and lactobacilli and at the same time inhibits growth of pathogenic bacteria such as Salmonella. It can also be used for the treatment of constipation, hepatic encephalopathy, tumour prevention, and to maintain blood glucose and insulin level. This review provides comprehensive information on the different techniques used for the production of lactulose, purification and analysis. Besides this mechanism of action and its potential applications in food and pharmaceutical industries have also been discussed.

Gluten-free sourdough wheat baked goods appear safe for young celiac patients: a pilot study

OBJECTIVES

This study was aimed at showing the safety, for young patients with celiac disease (CD), of sweet baked goods made of wheat flour, which was rendered gluten-free during sourdough fermentation.

METHODS AND RESULTS

As shown by R5 antibody-based sandwich and competitive enzyme-linked immunosorbent assay (ELISA), selected lactobacilli and fungal proteases, routinely used in bakeries, degraded gluten to <10 ppm during sourdough fermentation. The resulting flour was mainly a mixture of water-/salt-soluble low-size peptides and free amino acids. Gliadin and glutenin fractions extracted from the pepsin-trypsin (PT) digest of the fermented wheat flour induced the expression of interferon (IFN)-γ at the level comparable with the negative control. After fermentation, the wheat flour was spray dried and used for making sweet baked goods. Eight patients with CD in remission were enrolled for the clinical challenge, and they daily consumed 200 g of sweet baked goods equivalent to 10 g of native gluten. Hematology, serology (total serum IgA, IgG and IgA antigluten, endomysial and tissue transglutaminase IgA antibodies), and intestinal permeability analyses were carried out over time. One patient interrupted the trial after 15 days and another after 30 days only due to difficulties in the compliance of the daily consumption. All of the other patients showed normal values of hematology, serology, and intestinal permeability during 60 days of challenge.

CONCLUSIONS

This study showed that a wheat flour-fermented product, having gluten completely degraded, is not toxic for patients with CD. Nevertheless, these foods should not be recommended for patients with celiac disease until a formal trial has been done.

The rate of bloodstream infection is high in infants with short bowel syndrome: relationship with small bowel bacterial overgrowth, enteral feeding, and inflammatory and immune responses

OBJECTIVE

This pilot study in parenteral nutrition-dependent infants with short bowel syndrome (SBS) evaluated the impact of feeding route and intestinal permeability on bloodstream infection (BSI), small bowel bacterial overgrowth (SBBO), and systemic immune responses, as well as fecal calprotectin as a biomarker for SBBO.

STUDY DESIGN

Ten infants (ages 4.2-15.4 months) with SBS caused by necrotizing enterocolitis were evaluated. Nutritional assessment, breath hydrogen testing, intestinal permeability, fecal calprotectin, serum flagellin- and lipopolysaccharide-specific antibody titers, and proinflammatory cytokine concentrations (tumor necrosis factor-alpha [TNF-alpha], interleukin-1 beta, -6, and -8) were performed at baseline and at 60 and 120 days. Healthy, age-matched control subjects (n = 5) were recruited.

RESULTS

BSI incidence was high (80%), and SBBO was common (50%). SBBO increased the odds for BSI (>7-fold; P = .009). Calprotectin levels were higher in children with SBS and SBBO versus those without SBBO and healthy control subjects (P < .05). Serum TNF-alpha, was elevated at baseline versus controls. Serum TNF-alpha and interleukin-1 beta, -6, and -8 levels diminished with increased enteral nutrition. Anti-flagellin and anti-lipopolysaccharide immunoglobulin G levels in children with SBS were lower versus control subjects and rose over time.

CONCLUSION

In children with SBS, SBBO increases the risk for BSI, and systemic proinflammatory response decreases with increasing enteral feeding and weaning parenteral nutrition.

Lactulose/mannitol test and specificity, sensitivity, and area under curve of intestinal permeability parameters in patients with liver cirrhosis and Crohn's disease

The purpose of this study was to investigate and compare the specificity, sensitivity, and area under curve (AUC) of the lactulose/mannitol ratio, lactulose/creatinine ratio, and lactulose recovery and their diagnostic value for intestinal permeability assessment within the absorption lactulose/mannitol (L/M) test.

RESULTS

The value of the lactulose/mannitol ratio, lactulose/creatinine ratio, and the percentage of lactulose recovery in Crohn's disease (0.0763 +/- 0.0369; 99.62 +/- 67.87; 1.0478 +/- 0.6148) and in liver cirrhosis (0.0517 +/- 0.0365; 54.65 +/- 53.26; 0.838 +/- 0.929) were significantly different from the values measured in the control group (0.0123 +/- 0.0081; 10.95 +/- 7.07; 0.2438 +/- 0.1568), P < 0.0001-0.002). In Crohn's disease, specificity, sensitivity, and AUC were 100%, 89.5%, and 0.987, respectively, of the lactulose/mannitol ratio at a cut-off level of 0.022. In liver cirrhosis, the test characteristics were 88.5%, 84.2%, and 0.910 at a cut-off level of 0.018.

CONCLUSION

The lactulose/mannitol ratio was evaluated to have the highest diagnostic value to assess intestinal permeability.

A liquid chromatography/mass spectrometry method for the evaluation of intestinal permeability

OBJECTIVES

Lactulose to mannitol ratio (L/M) in urine is used as a non invasive assay to measure intestinal permeability. We describe here a rapid, specific and sensitive LC-MS/MS method for the measurement of these compounds in urine of children affected by abdominal recurrent pain (ARP).

DESIGN AND METHODS

The study has been performed on 50 children from the Pediatric Unit. The chromatographic separation was accomplished by using an NH(2)-column, the detection with a Q-Trap 2000 system.

RESULTS

Multiple calibration curve exhibited consistent linearity and reproducibility. Linear responses were observed in the concentration range 0-400 microg/mL for both mannitol and lactulose. Limits of detection were 12.5 mg/L for lactulose and 1.25 mg/L for mannitol with a signal-to-noise ratio of 10.

CONCLUSIONS

The comparison of L/M values of healthy children with those found in children affected by idiopathic ARP demonstrates that in the latter subjects an alteration of intestinal permeability occurs. The method can represent a useful tool to monitor the intestinal functionality in children with ARP conditions and help for an accurate patient discrimination for diet restrictions.

Identification and quantification of the osmodiuretic mannitol in urine for sports drug testing using gas chromatography-mass spectrometry

The osmodiuretic mannitol can be potentially misused in sports, owing to its urine diluting effect and the possibility to decrease bodyweight. To reveal a doping offence, resulting urinary mannitol concentrations after a prohibited intravenous application and a permitted oral intake have to be differentiated. Therefore, a reliable gas chromatography-mass spectrometry (GC-MS) method was established based on peracetyl derivatives of the analytes. All possible hexitols (allitol, galactitol, iditol, altritols, sorbitol and mannitol) that can occur in human urine were separated and identified on a phenyl-methylpolysiloxane column (HP-5MS) within 10.75 min, and the method demonstrated its capability for quantification purposes. The lower limit of detection and lower limit of quantification were estimated at 0.9 microg mL(-1) and 2.4 microg mL(-1), respectively, and the assay was validated for mannitol and sorbitol regarding the parameters specificity, linearity, intra- (<10%) and inter-day precision (<15%) and accuracy (92-102%). To investigate urinary mannitol concentrations after oral intake the method was applied to an excretion study, providing a mean urinary excretion of mannitol of 19.5%. Comparison of theoretically expected urinary levels after a common therapeutic dose of mannitol and preliminary results on physiological urinary mannitol levels were promising, regarding a threshold level for mannitol that can be utilised for doping control purposes.

Recent developments in sample preparation for chromatographic analysis of carbohydrates

Carbohydrates are a very important group of compounds due to their roles as structural materials, sources of energy, biological functions and environmental analytes; they are characterized by their structural diversity and the high number of isomers they present. While many advances have been made in carbohydrate analysis, the sample preparation remains difficult. This review aims to summarize the most important treatments which have been recently developed to be applied prior to the analysis of carbohydrates by chromatographic techniques. Due to the multiplicity of structures and matrices, many different techniques are required for clean-up, fractionation and derivatization. A number of new techniques which could be potentially adequate for carbohydrate characterization have also been revised.

Lactulose and mannitol intestinal permeability detected by capillary electrophoresis

Aim of this study was to set up a method by capillary electrophoresis to detect lactulose and mannitol in urine after an oral load, and to estimate the intestinal permeability in controls and in type I diabetes patients. The underivatized carbohydrates were monitored by indirect UV detection using sorbate, cetyltrimethylammonium bromide and LiOH as background electrolyte. Urines were purified by solid phase extraction, shaken with cation exchange resin, filtered and analysed. Carbohydrates migrated in <10 min in relation to their pK(a) and M(r). Controls (n = 33) and patients (n = 23) had an excretion ratio lactulose/mannitol 0.025 (0.018-0.051) and 0.067 (0.050-0.127), respectively (p < 0.01, median, interquartile range).

Simultaneous measurement of urinary polyols using gas chromatography/mass spectrometry

In the present study, we simultaneously measured several polyols, such as adonitol, arabitol, dulcitol, glucose, myo-inositol, mannitol, sorbitol, and xylitol, in urine by gas chromatography/mass spectrometry-positive chemical ionization. We also examined possible relationship between the levels of these metabolites and age in normal individuals. In order to proceed to its quantification by GC/MS, 200 microL of a urine sample were diluted with 3 ml of distilled water, lyophilized, acetylated, and then analyzed them. Using this method, we were able to quantify as little as 0.5-1.0 ng/microL, and we made the calibration curves to be linear from 0.25 to 250 ng/microL (r(2)>0.991). Analytical recoveries were over 89.4%, and the inter-day and intra-day variability for accuracy and reproducibility was less than 20%. In the normal urine sample, the levels of polyols were gender-differentiated and age-related. This simple GC/MS method is sensitive and allows the measurement of wide ranges of polyols using small amounts of urine. We conclude that the quantitation of urinary polyols using GC/MS appears to be a clinically useful method for assessing polyol-pathway activity.

Analysis of mannitol in pharmaceutical formulations using hydrophilic interaction liquid chromatography with evaporative light-scattering detection

This study demonstrates the use of hydrophilic interaction liquid chromatography (HILIC) for the separation of both active and inactive ingredients in pharmaceuticals from a single injection. Excipients commonly used in parenteral formulations were separated using a gradient method employing increasing aqueous composition. An evaporative light-scattering detector (ELSD) provided direct detection of inactive excipients and inorganic salts lacking UV chromophores. Analyses of Gemzar parenteral formulations using optimized isocratic HILIC-ELSD method conditions were performed based on retention time screening from the gradient assay. All of the components were efficiently separated using a TSK-Gel Amide 80 column including gemcitabine, mannitol, and sodium cation demonstrating the qualitative capability of the technique. The method was thoroughly validated for mannitol content to access the quantitative potential of the technique. Validation parameters included linearity, accuracy, specificity, solution stability, repeatability, and intermediate precision. Overall, the method described in this report proved to be very robust and represents a novel technique to conveniently separate and detect the active and inactive components in pharmaceuticals both quickly and accurately.

Simultaneous separation and quantitation of four antiepileptic drugs—a study with potential for use in patient drug level monitoring

The purpose of this study was to illustrate the applicability of high-performance liquid chromatography (HPLC) coupled with evaporative light scattering detector (ELSD) in simultaneously separating and quantitating four commonly used antiepileptic drugs (AEDs). A mixture of the four AEDs were separated using a C8 column using volatile mobile phases and were detected using ELSD. Optimal instrumental conditions were obtained by assessing the effect of various critical experimental parameters such as evaporator tube temperature, carrier gas flow rate, photomultiplier gain on separation efficiency, accuracy, reproducibility and sensitivity of measurement on all four AEDs. A novel, rapid, accurate, sensitive, reproducible and robust HPLC-ELSD method for simultaneous separation and quantitation of four commonly used AEDs was developed. The physical basis of the results obtained as a consequence of varying several critical experimental parameters has been explained. This study illustrates the potential for use of HPLC-ELSD in drug level monitoring of patients undergoing mono- or polytherapy for epilepsy.

Simultaneous gas-chromatographic measurement of rhamnose, lactulose and sucrose and their application in the testing gastrointestinal permeability

BACKGROUND

As it is important to test gastric and intestinal permeability simultaneously in gastrointestinal disorders such as Celiac disease, we developed a gas-chromatographic (GC) method to estimate rhamnose (L-rh), lactulose (Lacl) and sucrose (Suc) in urine.

METHODS

The method is based on the use of alditol acetate derivatives giving a lower number of GC peaks than reducing sugars do. Acetate derivatives are more stable and less expensive than GC silylates and keep the flame-detector cleaner. We checked the chemical stability of alditol acetates by verifying the reproducibility of the standard curve of a sugar derivative sample which had been stored for 2 months at -20 degrees C.

RESULTS

The calibration proved linear over the range 0.1-1 microg of sugar injected. Analytical sugar recovery was 88%+/-19.4% (mean+/-S.D.) for rhamnose, 105%+/-7.4% for sucrose and 102%+/-2.4% for lactulose. Mean within-day precision (CV) was 7.7% for rhamnose, 5.7% for sucrose and 1.9% for lactulose, and between-day (CV) was 6.7% for rhamnose, 3.9% for sucrose and 1.6% for lactulose. The rhamnose, lactulose and sucrose as the lactulose/rhamnose ratio clearly differentiated 25 healthy controls from 36 patients with active gluten-sensitive enteropathy.

CONCLUSIONS

A fast, reliable and cheap gas-chromatographic method is presented here to evaluate gastric and intestinal permeability.

Intestinal absorption and permeability in paediatric short-bowel syndrome: a pilot study

BACKGROUND

Sugar absorption tests are an effective, noninvasive way to assess intestinal permeability. The role of intestinal barrier integrity in complications and outcome of short-bowel syndrome is not known. The purpose of the study was to evaluate whether such tests provide information on the status of intestinal mucosa of these patients.

METHODS

Six children with short-bowel syndrome--median age, 12 months, and median small bowel length at birth, 30 cm--had a sugar test with 3-o-methyl-D-glucose, D-xylose, D-rhamnose, and melibiose approximately 2 months after operation. The melibiose/L-rhamnose ratio was used as an index of permeability, and percentages of 3-o-methyl-D-glucose and D-xylose absorbed were used as indices of absorption. Parenteral nutrition requirement, bowel length, liver disease, recent sepsis, and bacterial overgrowth were recorded.

RESULTS

Three patients had increased permeability, and all of them had had a recent episode of sepsis and severe liver disease. All subjects had malabsorption of 3-o-methyl-D-glucose, and five of six had malabsorption of D-xylose and L-rhamnose. The absorption of 3-o-methyl-D-glucose correlated with bowel length (r2 = 0.78; P = 0.04), whereas the absorption of D-xylose correlated with parenteral requirement (r2 = 0.66; P = 0.04) at that time.

CONCLUSIONS

Increased permeability was observed in three of six patients with short-bowel syndrome associated with a recent episode of sepsis and severe liver disease. Other indices of malabsorption correlated significantly with different clinical features of the disease. A prospective larger scale study in a homogeneous population is indicated to assess at multiple points during the disease course whether the test can be helpful in the management of these patients.